Construction machine and electric actuator for construction machine

Abstract

The invention provides a construction machine capable of swinging a boom with an electric motor as a drive source, and an electric actuator for the construction machine. An electric actuator for a construction machine is provided with: a drive device which is provided with an electric motor and is capable of outputting a torque centered on a rotational center axis; and a swing bracket fixed to the boom. The swing bracket receives torque from the driving device and can rotate around a rotation central axis parallel to the rotation central axis or the rotation central axis.

Description

Technical Field

[0001] The present invention relates to a construction machine and an electric actuator of the construction machine. Background Art

[0002] The excavator disclosed in Japanese Patent Application Laid-Open No. 2010-174615 comprises a travel device, a vehicle body, a boom, an arm, and a bucket. The travel device is self-propelled. The vehicle body is located above the travel device. The vehicle body includes a seat for the operator, etc. The boom extends forward from the vehicle body. The arm is connected to the top of the boom. The bucket is connected to the top of the arm. The boom is connected to the vehicle body so that it can swing left and right. The left and right swing of the boom is hydraulically driven.

[0003] Japanese Patent Application Laid-Open No. 2010-174615 discloses only hydraulic pressure as a power source for swinging the boom, and Japanese Patent Application Laid-Open No. 2010-174615 does not make any study on swinging the boom using a power source other than hydraulic pressure. Summary of the Invention

[0004] In one embodiment, a construction machine is provided. The construction machine comprises: a vehicle body; a drive device including an electric motor that outputs torque centered about a rotational axis extending vertically along the vehicle body; a swing bracket coupled to the vehicle body and configured to receive torque from the drive device and rotate about a rotational axis parallel to the rotational axis or about the rotational axis; and a boom fixed to the swing bracket.

[0005] In the above-mentioned construction machine, the swing bracket rotates by the torque output by the driving device including the electric motor, and the boom swings accordingly. That is, according to the above-mentioned structure, the boom can be swung using the electric motor as the driving source.

[0006] In another embodiment, an electric actuator for a construction machine is provided. The electric actuator comprises: a drive device including an electric motor that outputs torque centered about a rotational axis; and a swing bracket fixed to a boom and configured to receive torque from the drive device and rotate about a rotational axis parallel to the rotational axis or about the rotational axis.

[0007] In the electric actuator, the swing bracket rotates by the torque output by the drive device including the electric motor, and the boom swings accordingly. That is, according to the above structure, the boom can be swung using the electric motor as the driving source.

[0008] In one embodiment, the drive device includes: a transmission shaft, which is arranged in a first through hole provided in the vehicle body of the construction machinery and can rotate around the rotation center axis; the electric motor is installed on the vehicle body, and the output shaft is connected to the transmission shaft; the reducer is constructed to be installed at a position on the opposite side of the electric motor across the first through hole in the vehicle body, the input shaft is connected to the transmission shaft, and amplifies and outputs the torque output by the output shaft of the electric motor; and an output member is connected to the swing bracket and is constructed to receive the torque from the reducer and rotate around the rotation center axis, and the swing bracket is constructed to receive the torque from the output member and rotate around the rotation center axis.

[0009] In one embodiment, the electric actuator may further include a cylindrical pin in which the transmission shaft is disposed and arranged in the first through-hole together with the transmission shaft, wherein the swing bracket contacts the pin.

[0010] In one embodiment, the swing bracket may have opposing walls, which have a third through hole at a position opposite to the second through hole provided in the output member, and the electric actuator further has a connecting member connecting the output member and the opposing wall, the connecting member having: a base, which is arranged in the second through hole and the third through hole; and a cylindrical buffer portion, in which the base is arranged and is arranged in the second through hole and the third through hole together with the base, and the elastic modulus is smaller than that of the base.

[0011] In one embodiment, the swing bracket may include a facing wall facing the output member, and the electric actuator may further include a connecting member connecting the facing wall and the output member, with a gap being present between the facing wall and the output member.

[0012] In one embodiment, the drive device can be installed on the vehicle body of the construction machinery, the swing bracket is connected to the vehicle body in a manner that can rotate around the rotation center axis, and the electric actuator also has: a driving component, which is configured to receive torque from the drive device and rotate around the rotation center axis; a transmitted component, which is configured to be installed on the swing bracket and rotate around the rotation center axis; and a transmission mechanism, which is configured to cause the driving component and the transmitted component to rotate in a linked manner.

[0013] In one embodiment, the driving member may be a driving sprocket, which is annular with the rotation center axis as the center and has a plurality of teeth on the outer peripheral surface; the transmitted member is a driven sprocket, which is annular with the rotation center axis as the center and has a plurality of teeth on the outer peripheral surface; the transmission mechanism is a chain, which is wound around the driving sprocket and the driven sprocket.

[0014] In one embodiment, the driving member may be an annular driving pulley centered on the rotation center axis, the transmitted member may be an annular driven pulley centered on the rotation center axis, and the transmission mechanism may be a belt wound around the driving pulley and the driven pulley.

[0015] In one embodiment, the outer diameter of the driving member may be smaller than the outer diameter of the transmitted member.

[0016] In one embodiment, the construction machine may have an upper body and a lower body serving as the vehicle body, the upper body being located on the opposite side of the ground relative to the lower body of the construction machine, and being supported by a slewing bearing so as to be able to swivel relative to the lower body, when the slewing center axis is set as the first slewing center axis, the direction of the first slewing center axis when observed from the second slewing center axis serving as the slewing center axis of the upper body is set as the first direction, and the portion of the slewing bearing closest to the first slewing center axis in the first direction is set as a specific portion, at least a portion of the driving member is located on an imaginary line segment connecting the specific portion and the first slewing center axis.

[0017] In one embodiment, the construction machine may have an upper body and a lower body serving as the vehicle body, the upper body being located on the opposite side of the ground relative to the lower body of the construction machine and being supported by a slewing bearing so as to be rotatable relative to the lower body, the electric actuator also having one or more intermediate members, the one or more intermediate members being configured to be mounted on the vehicle body and to rotate around a central axis parallel to the rotation center axis, the transmission mechanism being configured to cause the one or more intermediate members, the driving member and the transmitted member to rotate in conjunction with each other, when the rotation center axis is set as a first rotation center axis, the direction of the first rotation center axis when viewed from a second rotation center axis serving as the rotation center axis of the upper body is set as a first direction, and the direction opposite to the first direction is set as a second direction, when viewed from the driving member, the one or more intermediate members are located on the first direction side, and when viewed from the second rotation center axis, the driving member and the driving device are located on the second direction side.

[0018] In one embodiment, the drive device may be mounted on a vehicle body of a construction machine, and the swing bracket is fixed to an output member of the drive device and rotates about the rotation center axis upon receiving torque from the drive device.

[0019] In one embodiment, the drive device may have a reducer configured to amplify and output the torque output by the electric motor, and the reducer may be configured to output the torque output by the electric motor centered on the rotation center axis to the swing bracket coaxially with the electric motor.

[0020] In one embodiment, the driving device may be located on a lower side relative to the swing bracket, and the swing bracket may be fixed to the output member of the driving device by a bolt.

[0021] In one embodiment, the swing bracket and the drive device may be aligned in a direction along the rotational axis. The electric actuator further comprises: a transmission member located between the drive device and the swing bracket and configured to transmit the drive device's torque to the swing bracket; an annular bearing mounted on a vehicle body of the construction machine, the transmission member penetrating the bearing and rotatably supporting the transmission member; a retaining member located on the opposite side of the swing bracket across the bearing in the direction of the rotational axis, the drive device penetrating the retaining member; and a buffer member connecting the retaining member and the vehicle body, having a smaller elastic modulus than that of the retaining member. The swing bracket is configured to receive the drive device's torque via the transmission member and rotate about the rotational axis.

[0022] In one embodiment, the bearing may be a first bearing of a plurality of bearings arranged in a direction along the rotation center axis.

[0023] In one embodiment, the drive device may be cylindrical centered about the rotational axis, and the swing bracket may be arranged along the rotational axis with the drive device, fixed to an output member of the drive device, receiving torque from the drive device and rotating about the rotational axis. The electric actuator may further include: a flange wall located on an opposite side of the swing bracket relative to the drive device along the rotational axis, supporting the drive device and fixed to the body of the construction machine; a retaining member located between the swing bracket and the flange wall, through which the drive device extends; a buffer member connecting the retaining member and the body, having a smaller elastic modulus than that of the retaining member; and a pin extending through the drive device and fixed to the flange wall.

[0024] In one embodiment, the swing bracket can be coupled to a vehicle body of the construction machine so as to be rotatable about the rotational center axis. Furthermore, the electric actuator further comprises: a pinion configured to receive torque from the drive unit and rotate about the rotational center axis; and a gear wall disposed opposite the pinion, the gear wall having an arcuate surface centered about a central axis parallel to the rotational center axis; and a plurality of teeth projecting from the arcuate surface and meshing with the teeth of the pinion, the arc diameter of the arcuate surface being larger than the outer diameter of the pinion. One of the gear wall and the drive unit is fixed to the swing bracket, and the other is fixed to the vehicle body.

[0025] In one embodiment, the arc surface can extend in a range of greater than 165 degrees and less than 195 degrees in a circumferential direction centered on a central axis parallel to the rotation center axis, and on the gear wall, the two ends of the arc in the arc surface are connected by a flat surface extending in a straight line.

[0026] In one embodiment, the electric actuator further comprises: an annular inner ring, which is mounted on the body of the construction machinery and is centered on the center axis of rotation; an annular outer ring, which is configured to be coaxially arranged with the inner ring and has a plurality of teeth on the outer peripheral surface, and is fixed to the swing bracket, and rotates together with the swing bracket around the center axis of rotation; a rolling body, which is configured to be located between the inner ring and the outer ring, and guides the inner ring and the outer ring to rotate relative to each other; and a pinion, which has teeth on the outer peripheral surface that mesh with the teeth of the outer ring, and is configured to be arranged at a position facing the outer peripheral surface of the outer ring, receives the torque output by the drive device, and rotates around the center axis of rotation.

[0027] On the other hand, a construction machine is provided. The construction machine comprises: a vehicle body; a cylindrical first member; a second member inserted into the interior of the first member from one end along the direction of the central axis of the first member and capable of reciprocating along the central axis of the first member; an electric motor configured to drive the second member to reciprocate relative to the first member; a swing bracket connected to the vehicle body so as to be rotatable about a rotational center axis extending vertically along the vehicle body; and a boom fixed to the swing bracket, the first member being connected to one of the vehicle body and the swing bracket while being rotatable about a center axis parallel to the rotational center axis, and the second member being connected to the other of the vehicle body and the swing bracket while being rotatable about a center axis parallel to the rotational center axis.

[0028] In the above-mentioned construction machine, the second member is driven by the electric motor to reciprocate relative to the first member. This reciprocating motion causes the swing bracket and boom to swing. That is, according to the above-mentioned structure, the boom can be swung using the electric motor as a driving source.

[0029] In another embodiment, an electric actuator for a construction machine is provided. The electric actuator comprises a cylindrical first member; a second member inserted into the first member from one end along the direction of the central axis of the first member and capable of reciprocating along the central axis of the first member; an electric motor configured to drive the second member to reciprocate relative to the first member; and a swing bracket connected to a vehicle body of the construction machine so as to be rotatable about a rotational center axis and fixed to a boom, the first member being connected to one of the vehicle body and the swing bracket while being rotatable about a center axis parallel to the rotational center axis, and the second member being connected to the other of the vehicle body and the swing bracket while being rotatable about a center axis parallel to the rotational center axis.

[0030] In the electric actuator, the electric motor drives the second member to reciprocate relative to the first member. This reciprocating motion causes the swing bracket and boom to swing. That is, with the above configuration, the boom can be swung using the electric motor as a driving source.

[0031] In one embodiment, the second member is cylindrical and extends along the central axis of the first member, and has an internal thread formed on its inner circumferential surface. Furthermore, the electric actuator further comprises: a screw shaft, configured to be inserted into the interior of the second member from an end of the second member opposite to the one side, having an external thread formed on its outer circumferential surface and rotating about the central axis of the second member in response to rotation of the electric motor; and a ball located between the screw shaft and the second member.

[0032] In one embodiment, the rotation center axis of the electric motor may extend parallel to the center axis of the second member at a position different from the center axis of the second member. The electric actuator further includes a transmission mechanism configured to transmit the rotation of the electric motor to the screw shaft.

[0033] In one embodiment, the first member defines a fluid chamber for supplying or discharging fluid, and the second member includes a piston that divides the fluid chamber into two parts along the central axis of the first member, and a rod that extends from the piston toward the one side. Furthermore, the electric actuator further includes a fluid circuit that supplies or discharges fluid to each of the two fluid chambers in response to a pump driven by the electric motor.

[0034] In one embodiment, the second member may be cylindrical and extend in a direction along the central axis of the first member, and may have a plurality of rack teeth arranged on its outer surface along the central axis of the first member. The electric actuator may further include a pinion gear rotatable about an axis intersecting the central axis of the second member and having teeth on its outer circumference that mesh with the rack teeth. The pinion gear is driven to rotate by the electric motor.

[0035] In one embodiment, the construction machine has an upper body and a lower body serving as the vehicle body, the upper body being located on the opposite side of the ground relative to the lower body of the construction machine and being supported by a rotary bearing so as to be able to rotate relative to the lower body, the rotation center axis of the electric motor being consistent with the center axis of the pinion, when the rotation center axis is set as the first rotation center axis, the imaginary line segment connecting the second rotation center axis serving as the center axis of rotation of the upper body and the first rotation center axis when looking down in the direction along the first rotation center axis is set as the first line segment, and the imaginary line segment connecting the end of the first member on the side opposite to the side inserted into the second member and the end of the one side of the second member in the direction along the center axis of the first member is set as the second line segment, the rotation center axis of the electric motor is located between the first line segment and the second line segment.

[0036] In another aspect, a construction machine is provided. The construction machine comprises: a vehicle body; an electric motor mounted on the vehicle body and configured to output torque centered about a rotational axis; a swing bracket coupled to the vehicle body so as to be rotatable about a rotational axis intersecting the rotational axis and extending vertically along the vehicle body; a conversion mechanism configured to convert torque of the electric motor centered about the rotational axis into torque centered about the rotational axis; a transmission member configured to transmit the torque converted by the conversion mechanism to the swing bracket; and a boom fixed to the swing bracket.

[0037] In this construction machine, the torque of the electric motor, after its direction has been converted by the conversion mechanism, is transmitted to the swing bracket via the transmission member. Furthermore, as the electric motor operates, the boom and the swing bracket swing together. In other words, in this configuration, the boom can be swung using the electric motor as the driving source.

[0038] In another embodiment, an electric actuator for a construction machine is provided. The electric actuator comprises: an electric motor configured to output torque centered about a rotational axis; a swing bracket fixed to a boom and connected to a body of the construction machine so as to be rotatable about a rotational axis extending in a direction intersecting the rotational axis; a conversion mechanism configured to convert torque of the electric motor centered about the rotational axis into torque centered about the rotational axis; and a transmission member configured to transmit the torque converted by the conversion mechanism to the swing bracket.

[0039] In this electric actuator, the torque of the electric motor, after its direction has been converted by the conversion mechanism, is transmitted to the swing bracket via the transmission member. Furthermore, as the electric motor operates, the boom and the swing bracket swing together. In other words, with this structure, the boom can be swung using the electric motor as the driving source.

[0040] In the above technical concept, the boom can be swung using the electric motor as a driving source. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a diagram schematically showing the overall structure of the excavator according to the first embodiment.

[0042] Figure 2 It is a diagram schematically showing the swinging operation of the boom according to the first embodiment.

[0043] Figure 3 This is an end view of the boom swing mechanism according to the first embodiment.

[0044] Figure 4 It is magnified Figure 3 An end view of a portion of .

[0045] Figure 5 It is a side view schematically showing an excavator according to the second embodiment.

[0046] Figure 6 It is a plan view schematically showing an excavator according to the second embodiment.

[0047] Figure 7 It is a plan view schematically showing a modified example of the excavator according to the second embodiment.

[0048] Figure 8 It is a plan view schematically showing a modified example of the excavator according to the second embodiment.

[0049] Figure 9 It is a side view schematically showing an excavator according to a third embodiment.

[0050] Figure 10It is a side view schematically showing an excavator according to a fourth embodiment.

[0051] Figure 11 It is a plan view schematically showing an excavator according to a fourth embodiment.

[0052] Figure 12 It is an end view schematically showing a power unit according to a fourth embodiment.

[0053] Figure 13 It is a plan view showing a state in which the boom according to the fourth embodiment is swung to the left.

[0054] Figure 14 It is a plan view showing a state in which the boom according to the fourth embodiment is swung to the right.

[0055] Figure 15 It is a cross-sectional view schematically showing a modified example of the power unit according to the fourth embodiment.

[0056] Figure 16 It is a cross-sectional view schematically showing a modified example of the power unit according to the fourth embodiment.

[0057] Figure 17 It is schematically represented Figure 16 A diagram showing an example of a power unit configuration.

[0058] Figure 18 It is schematically represented Figure 16 A three-dimensional view of the first component and the second component of the power unit.

[0059] Figure 19 It is a side view schematically showing an excavator according to a fifth embodiment.

[0060] Figure 20 It is a side view schematically showing a modified example of the cushioning member of the fifth embodiment.

[0061] Figure 21 It is a side view schematically showing a modified example of the excavator according to the fifth embodiment.

[0062] Figure 22 It is a side view schematically showing an excavator according to the sixth embodiment.

[0063] Figure 23 It is a plan view schematically showing a gear wall and a pinion gear according to the sixth embodiment.

[0064] Figure 24 It is a side view schematically showing a modified example of the excavator according to the sixth embodiment.

[0065] Figure 25It is a side view schematically showing an excavator according to the seventh embodiment.

[0066] Figure 26 It is a side view schematically showing an excavator according to the eighth embodiment. DETAILED DESCRIPTION

[0067] <First embodiment>

[0068] Below, use Figures 1 to 4 A first embodiment of a construction machine and an electric actuator for the construction machine will be described. It should be noted that the drawings may sometimes show structural components in an enlarged manner to facilitate understanding. Furthermore, the dimensional ratios of structural components may differ from the actual dimensional ratios or the dimensional ratios in other drawings.

[0069] Overall Structure

[0070] like Figure 1 As shown, an excavator 500 as a construction machine has a travel device 510, a mother machine 520 as a vehicle body, a boom 530, a dipper 540, and a bucket 550. The travel device 510 includes a crawler track for travel, etc. The mother machine 520 is located on the side opposite to the road surface across the travel device 510. The mother machine 520 includes a seat for operators and a battery storage unit, etc. In addition, Figure 1 In the figure, the appearance of the passenger seat and the like are omitted. In the present embodiment, up, down, left, right, front and back are defined based on the excavator 500. That is, the direction in which the mother machine 520 is located when viewed from the travel device 510 is the upward direction. In addition, the front direction when the operator is seated on the passenger seat of the mother machine 520 is the front direction. The mother machine 520 can rotate left and right relative to the travel device 510 with an axis extending in a substantially upward direction as the center. The boom 530 extends from the mother machine 520 toward the front side. The details of the boom 530 will be described later. The arm 540 is in the shape of an elongated strip. The base end of the arm 540 is connected to the top end of the boom 530 on the side opposite to the mother machine 520. The arm 540 can rotate relative to the boom 530 with the base end of the arm 540 as the center. The arm 540 extends from the boom 530 toward the front side. The base end portion of the bucket 550 is connected to the tip end portion of the arm 540 on the opposite side from the boom 530. The bucket 550 is rotatable relative to the arm 540 about the base end portion of the bucket 550. The bucket 550 has a box shape with an opening.

[0071] <Boom swing mechanism>

[0072] The excavator 500 has a boom swing mechanism 10 at the connection portion between the base machine 520 and the boom 530. The boom swing mechanism 10 constitutes an electric actuator. Figure 2As shown, the boom swing mechanism 10 is a mechanism for swinging the boom 530 left and right relative to the mother machine 520. The boom swing mechanism 10 of this embodiment includes the mother machine 520 as a structural member of the boom swing mechanism 10. The front part of the mother machine 520 is referred to as the mother machine front part 520A. Figure 3 As shown, the front portion 520A of the main machine has an overall rectangular parallelepiped shape. The front portion 520A has a first through-hole 520H. The first through-hole 520H extends vertically through the front portion 520A. The central axis Q of the first through-hole 520H extends generally in the upward direction. In the various drawings, some parts of the boom swing mechanism 10 are shown in top view, omitting the cross-sectional structure of some components.

[0073] <First Holding Member>

[0074] like Figure 3 As shown, the boom swing mechanism 10 has a first retaining member 41. The first retaining member 41 is located on the upper side relative to the front portion 520A of the mother machine. The first retaining member 41 has a first mounting wall 41A, a first vertical wall 41B and a first retaining wall 41C. The first mounting wall 41A is arranged along the upper surface of the front portion 520A of the mother machine. The first mounting wall 41A is fixed to the upper surface of the front portion 520A of the mother machine by bolts B. In addition, Figure 1 、 Figure 3 and Figure 4 The bolt B is dotted. The first vertical wall 41B extends upward from the front end of the first mounting wall 41A. The first retaining wall 41C extends forward from the upper end of the first vertical wall 41B. The first retaining wall 41C has a through hole 41H. The through hole 41H passes through the first retaining wall 41C from top to bottom. The center axis Q of the through hole 41H is roughly consistent with the center axis Q of the first through hole 520H. In addition, Figure 1 、 Figure 3 and Figure 4 In FIG. 5 , a common reference numeral Q is assigned to an axis whose central axis substantially coincides with that of the first through hole 520H.

[0075] Electric Motor

[0076] The boom swing mechanism 10 has an electric motor 20. The entire electric motor 20 is located on the upper side relative to the first retaining wall 41C. The electric motor 20 has a housing 20A and an output shaft 20B. The housing 20A is fixed to the upper surface of the first retaining wall 41C. That is, the housing 20A is mounted on the front part 520A of the mother machine via the first retaining member 41. The housing 20A accommodates a stator and a rotor, etc., which are not shown in the figure. The output shaft 20B extends inside the housing 20A and protrudes downward relative to the housing 20A. The output shaft 20B is cylindrical. The diameter of the output shaft 20B is smaller than the diameter of the through hole 41H of the first retaining wall 41C. The center axis Q of the output shaft 20B is roughly consistent with the center axis Q of the through hole 41H of the first retaining wall 41C. The output shaft 20B can rotate about the center axis Q of the output shaft 20B and can rotate relative to the housing 20A. The output shaft 20B can receive power from a battery (not shown) and rotate in both forward and reverse directions.

[0077] <Transmission shaft>

[0078] The boom swing mechanism 10 includes a transmission shaft 25. The transmission shaft 25 is disposed within the first through-hole 520H in the front portion 520A of the mother machine. The transmission shaft 25 extends through the first through-hole 520H. The transmission shaft 25 is cylindrical in shape. The central axis Q of the transmission shaft 25 is substantially aligned with the central axis Q of the first through-hole 520H. Hereinafter, the direction along the central axis Q of the transmission shaft 25 will be referred to as the axial direction. Furthermore, the radial direction centered on the central axis Q of the transmission shaft 25 will be referred to as the radial direction. Furthermore, the circumferential direction centered on the central axis Q of the transmission shaft 25 will be referred to as the circumferential direction. In the axial direction, the transmission shaft 25 is larger than the first through-hole 520H. Furthermore, the transmission shaft 25 protrudes both upward and downward relative to the first through-hole 520H. The upper end of the transmission shaft 25 is connected to the output shaft 20B of the electric motor 20. For example, the upper end of the transmission shaft 25 and the output shaft 20B of the electric motor 20 are fixed to each other via a spline connection. The central axis Q of the transmission shaft 25 is substantially aligned with the central axis Q of the output shaft 20B. The transmission shaft 25 is coaxial with the output shaft 20B and rotates integrally with the output shaft 20B.

[0079] <Sales>

[0080] The boom swing mechanism 10 includes a pin 28. The pin 28 is positioned within the first through-hole 520H in the front portion 520A of the mother machine. The pin 28 extends through the first through-hole 520H. The pin 28 is cylindrical in shape. The center axis Q of the pin 28 is substantially aligned with the center axis Q of the first through-hole 520H. The inner diameter of the pin 28 is larger than the diameter of the transmission shaft 25. Furthermore, the transmission shaft 25 is positioned within the pin 28. The transmission shaft 25 extends through the pin 28. Thus, the pin 28 and the transmission shaft 25 are positioned within the first through-hole 520H together. In the axial direction, the pin 28 is larger than the first through-hole 520H and smaller than the transmission shaft 25. Furthermore, the pin 28 protrudes both upward and downward relative to the first through-hole 520H. The upper end of the pin 28 is located below the upper end of the transmission shaft 25. The lower end of the pin 28 is located above the lower end of the transmission shaft 25. The lower end of pin 28 is supported by the facing wall 53, described later. The outer diameter of pin 28 is slightly smaller than the diameter of first through-hole 520H. Therefore, a small gap (not shown) exists radially between the outer circumferential surface of pin 28 and the inner surface of first through-hole 520H. This gap is referred to as the first gap. A limiting member C, extending from the front surface of the mother machine front portion 520A to pin 28, is inserted into pin 28. While limiting member C prevents circumferential movement of pin 28, it allows radial movement within the first gap. The gap between the inner circumferential surface of pin 28 and transmission shaft 25 is referred to as the second gap. The second gap is larger in radial direction than the first gap. Therefore, even if pin 28 moves radially within the first gap, the inner circumferential surface of pin 28 does not contact transmission shaft 25. Furthermore, a sealing member S1 is disposed between the inner circumferential surface of pin 28 and transmission shaft 25 at the upper end of pin 28 to prevent the entry of foreign matter.

[0081] <Second Holding Member>

[0082] The boom swing mechanism 10 has a second holding member 42. The second holding member 42 is located at the lower side relative to the front portion 520A of the mother machine. Figure 4 As shown, the second retaining member 42 includes a second mounting wall 42A, a second upright wall 42B, and a second retaining wall 42C. The second mounting wall 42A is positioned along the lower surface of the front portion 520A of the mother machine. The second mounting wall 42A is secured to the lower surface of the front portion 520A of the mother machine by bolts B. The second upright wall 42B extends downward from the front end of the second mounting wall 42A. The second retaining wall 42C extends forward from the lower end of the second upright wall 42B. The speed reducer 70 is located on the upper surface of the second retaining wall 42C. The speed reducer 70 will be described in detail later.

[0083] Output components

[0084] like Figure 4As shown, the boom swing mechanism 10 has an output member 30. The output member 30 is located between the reducer 70 and the front part 520A of the mother machine. The output member 30 has an output wall 32 and a protruding wall 34. The output wall 32 is in the shape of a circular plate. The central axis Q of the output wall 32 is roughly consistent with the central axis Q of the transmission shaft 25. The output wall 32 has a plurality of second through holes 32H. Each second through hole 32H is located at the end portion of the output wall 32 close to the outer periphery. The plurality of second through holes 32H are arranged at equal intervals along the circumferential direction. Each second through hole 32H passes through the output wall 32 from top to bottom. The central axis of each second through hole 32H is roughly parallel to the central axis Q of the output wall 32. In addition, a circumferential portion of the end portion of the output wall 32 close to the outer periphery is located at a position forward of the front part 520A of the mother machine.

[0085] The protruding wall 34 protrudes from the upper surface of the output wall 32. The protruding wall 34 is located at the inner peripheral end of the output wall 32. The protruding wall 34 extends annularly along the central hole of the output wall 32. The inner surface of the protruding wall 34 is flush with the inner surface of the central hole of the output wall 32.

[0086] <Swinging Wall>

[0087] like Figure 3 As shown, the boom swing mechanism 10 includes a swing wall 50. The swing wall 50 includes a facing wall 53, a guide wall 59, an intermediate wall 57, and a contact wall 54. The swing wall 50 is an example of a swing bracket.

[0088] like Figure 4 As shown, the facing wall 53 is located between the upper surface of the output wall 32 and the lower surface of the front portion 520A of the mother machine. The facing wall 53 is in the shape of a circular plate. The diameter of the circle of the facing wall 53 is approximately the same as the outer diameter of the output wall 32. The central axis Q of the circular plate of the facing wall 53 is approximately aligned with the central axis Q of the output wall 32. In this position, the facing wall 53 is supported by the output wall 32 via a washer W (described later).

[0089] The facing wall 53 has a central hole 53A. The central hole 53A extends vertically through the facing wall 53. The central axis Q of the central hole 53A is substantially aligned with the central axis Q of the facing wall 53. The diameter of the central hole 53A is substantially aligned with the inner diameter of the pin 28. The lower end of the transmission shaft 25, which is disposed within the pin 28, is positioned within the central hole 53A.

[0090] The facing wall 53 has a central recess 53U. The central recess 53U is recessed upward from the bottom surface of the facing wall 53. The central recess 53U is cylindrical. The central axis Q of the cylinder of the central recess 53U is approximately aligned with the central axis Q of the central hole 53A. The diameter of the cylinder of the central recess 53U is slightly larger than the outer diameter of the protruding wall 34 of the output member 30. The protruding wall 34 extends into the central recess 53U. A sealing member S2 is disposed between the side surface of the central recess 53U and the outer peripheral surface of the protruding wall 34 to prevent the intrusion of foreign matter.

[0091] A portion of the facing wall 53 that is radially outward of the central recess 53U is referred to as a specific portion 53P. The lower surface of the specific portion 53P faces the upper surface of the output wall 32 in the axial direction.

[0092] The facing wall 53 has a plurality of third through-holes 53H. Each third through-hole 53H is provided for each second through-hole 32H in the output wall 32. That is, each third through-hole 53H is provided in a group with a plurality of second through-holes 32H. Furthermore, the number of third through-holes 53H matches the number of second through-holes 32H. Each third through-hole 53H is located at an outer peripheral end of the specific portion 53P. In both the circumferential and radial directions, each third through-hole 53H is positioned at the same position as the second through-hole 32H with which it is grouped. The central axis of each third through-hole 53H is substantially aligned with the central axis of the second through-hole 32H with which it is grouped. That is, each third through-hole 53H faces the second through-hole 32H with which it is grouped. The diameter of each third through-hole 53H is substantially aligned with the diameter of each second through-hole 32H.

[0093] A plurality of washers W are sandwiched between a specific portion 53P of the facing wall 53 and the output wall 32. Each washer W is in the shape of a circular plate. A washer W is provided for each third through-hole 53H. That is, each washer W is provided in a group with the plurality of third through-holes 53H and the second through-hole 32H. In the circumferential and radial directions, each washer W is positioned at the same position as the third through-hole 53H with which it is grouped. The presence of the washer W between the specific portion 53P and the output wall 32 creates a gap in the axial direction between the specific portion 53P and the output wall 32 that is equivalent to the thickness of the washer W. This gap is referred to as the third gap. The axial dimension of the third gap is greater than the radial dimension of the first gap.

[0094] <Guide wall>

[0095] like Figure 4As shown, the guide wall 59 protrudes from the upper surface of the facing wall 53. The guide wall 59 is integrally molded with the facing wall 53. The guide wall 59 has a cylindrical shape. The central axis Q of the guide wall 59 is approximately aligned with the central axis Q of the facing wall 53. The inner diameter of the guide wall 59 is slightly larger than the outer diameter of the pin 28. The inner circumferential surface of the guide wall 59 and the inner circumferential portion of the facing wall 53 located radially inward of the guide wall 59 define a recessed portion for accommodating the lower end of the pin 28. This inner circumferential portion supports the lower end surface of the pin 28.

[0096] <Middle wall>

[0097] like Figure 3 As shown, the intermediate wall 57 protrudes from the upper surface of the facing wall 53. The intermediate wall 57 is integrally molded with the facing wall 53. The intermediate wall 57 is located in the forward portion of the facing wall 53. The intermediate wall 57 surrounds the portion of the front section 520A of the mother machine that is forward of the pin 28 from the outside. Specifically, the intermediate wall 57 faces the front surface of the mother machine front section 520A and the portions of the left and right side surfaces of the mother machine front section 520A that are forward of the pin 28. For example, when viewed from above, the intermediate wall 57 has an arc shape centered about the central axis Q of the first through-hole 520H. Radially, the intermediate wall 57 is located slightly inward of the third through-hole 53H of the facing wall 53. Furthermore, the upper end of the intermediate wall 57 is located above the upper surface of the front section 520A and below the lower surface of the first retaining wall 41C of the first retaining member 41.

[0098] <Contact wall>

[0099] like Figure 3As shown, the contact wall 54 is located on the upper side as a whole relative to the upper end of the intermediate wall 57. The contact wall 54 includes a main body 54A and an extension 54B. The main body 54A is shaped to block the opening on the upper surface of the intermediate wall 57 and extend from the upper surface opening to the rear side. The rear end of the main body 54A reaches between the upper surface of the mother machine front portion 520A and the lower surface of the first retaining wall 41C. Multiple parts of the front portion of the main body 54A are fixed to the upper end of the intermediate wall 57 by bolts B. The main body 54A has a through hole. The through hole is located in the rear portion of the main body 54A. The through hole passes through the main body 54A from top to bottom. The extension 54B protrudes from the lower surface of the main body 54A. The extension 54B is cylindrical. The center axis Q of the extension 54B is roughly consistent with the center axis Q of the through hole of the main body 54A. The inner diameter of the extension portion 54B is substantially identical to the diameter of the through-hole in the main body portion 54A. The inner circumferential surface of the extension portion 54B and the inner surface of the through-hole in the main body portion 54A form a continuous fourth through-hole 54H. The center axis Q of the fourth through-hole 54H is substantially identical to the center axis Q of the pin 28. The diameter of the fourth through-hole 54H is substantially identical to the outer diameter of the pin 28. The portion of the pin 28 that protrudes upward relative to the first through-hole 520H is inserted into the fourth through-hole 54H. The inner surface of the fourth through-hole 54H contacts the outer circumferential surface of the pin 28. Furthermore, the lower end surface of the extension portion 54B is supported by the upper surface of the front portion 520A of the mother machine.

[0100] <Boom>

[0101] like Figure 1 and Figure 3 As shown, the boom swing mechanism 10 of the present embodiment includes a boom 530 as a structural member of the boom swing mechanism 10 .

[0102] The boom 530 includes a base wall 534, a connecting shaft 532, and a boom body 531. The base wall 534 extends forward relative to the intermediate wall 57. The base wall 534 is fixed to the surface of the intermediate wall 57 opposite the surface facing the front portion 520A of the mother machine. As described above, the contact wall 54 and the facing wall 53 are fixed to the intermediate wall 57. That is, the contact wall 54 and the facing wall 53 are fixed to the base wall 534 via the intermediate wall 57.

[0103] The connecting shaft 532 connects the base wall 534 and the boom body 531. The connecting shaft 532 is cylindrical. The central axis of the connecting shaft 532 extends leftward and rightward. The connecting shaft 532 receives power from an electric motor (not shown) and is rotatable relative to the base wall 534.

[0104] like Figure 1 As shown in FIG, the arm body 531 is in the shape of an elongated strip. One end of the arm body 531 is fixed to the connecting shaft 532. Figure 1As shown by arrow P1, the boom body 531 rotates integrally with the connecting shaft 532. The arm 540 is connected to the other end of the boom body 531.

[0105] <Connecting components>

[0106] like Figure 4 As shown, the boom swing mechanism 10 has a plurality of connecting members 90. The connecting member 90 is provided for each second through-hole 32H of the output wall 32. That is, each connecting member 90 is provided in a group with a plurality of second through-holes 32H. Each connecting member 90 has a base 91 and a buffer portion 92. The base 91 has a stepped shape. That is, the base 91 has a cylindrical first portion 91A and a cylindrical second portion 91B having a diameter larger than that of the first portion 91A. The diameter of the second portion 91B is larger than the diameter of the second through-hole 32H. The central axis of the first portion 91A and the central axis of the second portion 91B are substantially aligned. The base 91 is made of an iron-based metal.

[0107] The buffer portion 92 is cylindrical. The inner diameter of the buffer portion 92 is substantially the same as the diameter of the first portion 91A of the base 91. The outer diameter of the buffer portion 92 is substantially the same as the diameter of the second through hole 32H. The first portion 91A of the base 91 is arranged inside the buffer portion 92. The first portion 91A of the base 91 passes through the buffer portion 92. The central axis of the buffer portion 92 is substantially the same as the central axis of the base 91. The buffer portion 92 is made of rubber. That is, the buffer portion 92 is made of a material that is softer than the base 91. In other words, the elastic modulus of the buffer portion 92 is smaller than the elastic modulus of the base 91.

[0108] The buffer portion 92, along with the first portion 91A of the base 91, is positioned within the set of second through-holes 32H, washers W, and third through-holes 53H. Together with the first portion 91A, the buffer portion 92 penetrates the second through-hole 32H, washers W, and third through-holes 53H. The central axis of the buffer portion 92 is substantially aligned with the central axes of the second through-holes 32H and the third through-holes 53H. The outer peripheral surface of the buffer portion 92 contacts the inner surfaces of the second through-holes 32H and the third through-holes 53H. Furthermore, the second portion 91B of the base 91 is positioned below the lower ends of the buffer portion 92 and the second through-hole 32H. The upper end of the first portion 91A of the base 91 protrudes upward relative to the upper ends of the buffer portion 92 and the third through-hole 53H. The portion of the first portion 91A that protrudes from the buffer portion 92 and the third through-hole 53H is secured by a nut N. The vertical position of the connecting member 90 is defined by the second portion 91B and the nut N. Furthermore, the output wall 32 and the facing wall 53 are connected by the connecting member 90. As described above, the facing wall 53 is fixed to the base wall 534 of the boom 530. That is, the output wall 32 is connected to the boom 530 via the connecting member 90 and the facing wall 53.

[0109] Reducer

[0110] like Figure 3 As shown, the boom swing mechanism 10 includes a speed reducer 70. The speed reducer 70 is located on the opposite side of the electric motor 20 across the first through hole 520H of the parent machine 520. The speed reducer 70 is a transmission that changes the rotational speed of the output shaft 20B of the electric motor 20 and outputs the speed.

[0111] The speed reducer 70 includes a gear carrier 80 . The gear carrier 80 includes a first wall 81 , a second wall 82 , and a plurality of columnar walls 83 .

[0112] like Figure 4 As shown, the first wall 81 is located on the upper surface of the second retaining wall 42C. The first wall 81 is disk-shaped. The lower surface of the first wall 81 contacts the upper surface of the second retaining wall 42C. The first wall 81 is fixed to the upper surface of the second retaining wall 42C by bolts B. In other words, the first wall 81 and the reducer 70 are mounted to the front portion 520A of the mother machine via the second retaining member 42. The central axis Q of the disk of the first wall 81 is substantially aligned with the central axis Q of the output wall 32.

[0113] The first wall 81 has an input shaft hole 81A. The input shaft hole 81A is located near the center of the first wall 81. The input shaft hole 81A extends vertically through the first wall 81. The central axis Q of the input shaft hole 81A substantially coincides with the central axis Q of the first wall 81. A sealing member K is disposed at the lower end of the input shaft hole 81A.

[0114] The first wall 81 has a plurality of eccentric shaft holes 81B. The number of eccentric shaft holes 81B is, for example, three. Each eccentric shaft hole 81B is radially offset from the central axis Q of the first wall 81. Each eccentric shaft hole 81B extends vertically through the first wall 81. The plurality of eccentric shaft holes 81B are arranged at equal intervals along the circumferential direction. Furthermore, a sealing member K is disposed at the lower end of each eccentric shaft hole 81B.

[0115] A plurality of columnar walls 83 protrude from the upper surface of the first wall 81. For example, there are three columnar walls 83. Each columnar wall 83 is radially offset from the central axis Q of the first wall 81. Each columnar wall 83 is cylindrical. The plurality of columnar walls 83 are circumferentially spaced at equal intervals. Each columnar wall 83 is integrally formed with the first wall 81.

[0116] The second wall 82 is located above each column wall 83. The structure of the second wall 82 is essentially the same as that of the first wall 81. Specifically, the second wall 82 is disk-shaped and includes an input shaft hole 82A that is paired with the input shaft hole 81A in the first wall 81. The center axis Q of the input shaft hole 82A in the second wall 82 is approximately aligned with the center axis Q of the input shaft hole 81A in the first wall 81. The second wall 82 includes a plurality of eccentric shaft holes 82B that are paired with the plurality of eccentric shaft holes 81B in the first wall 81. In other words, the number of eccentric shaft holes 82B in the second wall 82 is the same as the number of eccentric shaft holes 81B in the first wall 81. The center axes of the paired eccentric shaft holes 81B, 82B are approximately aligned with each other. The second wall 82 is fixed to the upper end surface of each column wall 83 by bolts B. The upper surface of the second wall 82 faces the bottom of the central recess 53U of the facing wall 53. The upper surface of the second wall 82 is located at a position spaced apart from the bottom of the central recess 53U. The diameter of the circle of the second wall 82 is slightly smaller than the diameter of the circle of the first wall 81.

[0117] <Box>

[0118] like Figure 4 As shown, the reducer 70 has a housing 75. The housing 75 is located on the upper side relative to the first wall 81. The housing 75 has a housing body 75A and a plurality of teeth 75B. The housing body 75A is cylindrical. The outer diameter of the housing body 75A is roughly the same as the diameter of the circle of the first wall 81. The inner diameter of the housing body 75A is larger than the diameter of the circle of the second wall 82. The inner diameter of the housing body 75A is roughly the same as the diameter of the central hole of the output wall 32. The central axis Q of the housing body 75A is roughly the same as the central axis Q of the output wall 32. The lower end face of the housing body 75A is opposite to the outer peripheral portion of the upper surface of the first wall 81. The upper end face of the housing body 75A is opposite to the lower surface of the output wall 32. The housing body 75A is fixed to the output wall 32 by bolts B.

[0119] A plurality of teeth 75B protrude from the inner circumferential surface of the housing body 75A. The plurality of teeth 75B are arranged at equal intervals along the circumferential direction. In the axial direction, each tooth 75B is located near the center of the housing body 75A. In the axial direction, bearings G are located on the upper and lower sides of each tooth 75B. The upper bearing G is located between the inner circumferential surface of the housing body 75A and the outer circumferential surface of the second wall 82. The lower bearing G is located between the inner circumferential surface of the housing body 75A and the stepped surface of the first wall 81. Each bearing G rotatably supports the housing body 75A. Moreover, by being supported by each bearing G, the housing body 75A can rotate relative to the gear rack 80.

[0120] <External gear>

[0121] The speed reducer 70 includes a first external gear 71. The first external gear 71 is located between the first wall 81 and the second wall 82 of the gear carrier 80 and within the housing body 75A. In the drawings, the first external gear 71 and the second external gear 72, described later, are shown from the inner side of a cutaway surface to facilitate understanding. The first external gear 71 is generally disk-shaped. Its diameter is smaller than the inner diameter of the housing body 75A. The center axis of the disk of the first external gear 71 is approximately parallel to the center axis Q of the housing body 75A. A plurality of teeth are formed on the outer circumferential surface of the first external gear 71. The teeth are arranged at equal intervals along the circumferential direction. Illustration of the teeth of the first external gear 71 is omitted in the drawings. The teeth located within a portion of the circumferential range of the teeth mesh with the teeth 75B of the housing body 75. On the other hand, the teeth located outside of this portion of the circumferential range of the teeth have clearances between them and the teeth 75B of the housing body 75.

[0122] The first external gear 71 has an input shaft hole X1. The input shaft hole X1 is located near the center of the first external gear 71. The input shaft hole X1 passes through the first external gear 71 vertically. The input shaft hole X1 communicates with the input shaft hole 81A of the first wall 81.

[0123] The first external gear 71 has a plurality of eccentric shaft holes X2. These eccentric shaft holes X2 are arranged in groups with the plurality of eccentric shaft holes 81B provided in the first wall 81. That is, the number of eccentric shaft holes X2 is the same as the number of eccentric shaft holes 81B provided in the first wall 81. Each eccentric shaft hole X2 is radially offset from the center axis of the first external gear 71. Each eccentric shaft hole X2 extends vertically through the first external gear 71. Each eccentric shaft hole X2 communicates with the group of eccentric shaft holes 81B in the first wall 81.

[0124] The first external gear 71 has a plurality of cylindrical holes X3. Each cylindrical hole X3 is radially offset from the central axis of the first external gear 71. Each cylindrical hole X3 vertically penetrates the first external gear 71. A cylindrical hole X3 is provided for each cylindrical wall 83. Furthermore, the cylindrical wall 83 extends through each cylindrical hole X3.

[0125] The reducer 70 includes a second external gear 72. The second external gear 72 is located between the first external gear 71 and the second wall 82 of the gear carrier 80, and is located inside the housing body 75A. The structure of the second external gear 72 is basically the same as that of the first external gear 71. That is, the second external gear 72 has a column hole Y3 for each column wall 83. In addition, the second external gear 72 has an input shaft hole Y1 near the center of the second external gear 72. The input shaft hole Y1 is connected to the input shaft hole X1 of the first external gear 71 and the input shaft hole 82A of the second wall 82. As a result, the input shaft hole 81A of the first wall 81, the input shaft hole X1 of the first external gear 71, the input shaft hole Y1 of the second external gear 72, and the input shaft hole 82A of the second wall 82 form a continuous first connecting hole. The second external gear 72 also has a plurality of eccentric shaft holes Y2, each paired with a plurality of eccentric shaft holes X2 provided in the first external gear 71 and a plurality of eccentric shaft holes 82B provided in the second wall 82. Each eccentric shaft hole Y2 communicates with the paired eccentric shaft holes X2 in the first external gear 71 and the paired eccentric shaft holes 82B in the second wall 82. As a result, the eccentric shaft holes 81B in the first wall 81, the eccentric shaft holes X2 in the first external gear 71, the eccentric shaft holes Y2 in the second external gear 72, and the eccentric shaft holes 82B in the second wall 82 form a continuous second communicating hole. There are a plurality of second communicating holes, corresponding to the number of eccentric shaft holes 81B in the first wall 81. Furthermore, the second communicating holes are arranged at equal intervals along the circumferential direction.

[0126] Crankshaft

[0127] The speed reducer 70 includes a plurality of crankshafts 77. The crankshafts 77 are provided for each of the continuous second communication holes formed by the eccentric shaft hole 81B and the like in the first wall 81. The crankshaft 77 includes a main shaft portion 77P, a first eccentric portion 77A, and a second eccentric portion 77B.

[0128] Most of the main shaft portion 77P is located in the second connecting hole. The main shaft portion 77P is cylindrical. The main shaft portion 77P extends in the axial direction. The upper end portion of the main shaft portion 77P protrudes upward relative to the upper end of the second connecting hole, that is, the upper end of the eccentric shaft hole 82B of the second wall 82. In addition, a bearing L is located between the outer peripheral surface of the main shaft portion 77P and the inner surface of the eccentric shaft hole 82B of the second wall 82. The main shaft portion 77P is supported by the bearing L so as to be rotatable. Although not shown in the figure, the main shaft portion 77P is also supported by the bearing so as to be rotatable within the eccentric shaft hole 81B of the first wall 81.

[0129] The first eccentric portion 77A is located midway along the main shaft portion 77P in the axial direction. The first eccentric portion 77A is located within the eccentric shaft hole X2 of the first external gear 71. The first eccentric portion 77A protrudes from the outer peripheral surface of the main shaft portion 77P. When viewed from above in the axial direction, the outer shape of the first eccentric portion 77A is circular. When viewed from above in the axial direction, the center of the first eccentric portion 77A is offset from the center of the main shaft portion 77P. The bearing J is located between the outer peripheral surface of the first eccentric portion 77A and the inner surface of the eccentric shaft hole X2 of the first external gear 71. The first eccentric portion 77A is supported by the bearing J so as to be rotatable.

[0130] The second eccentric portion 77B is located midway along the main shaft portion 77P in the axial direction. The second eccentric portion 77B is located within the eccentric shaft hole Y2 of the second external gear 72. Similar to the first eccentric portion 77A, the second eccentric portion 77B protrudes from the outer peripheral surface of the main shaft portion 77P. When viewed from above in the axial direction, the outer shape of the second eccentric portion 77B is circular. When viewed from above in the axial direction, the center of the second eccentric portion 77B is offset from the center of the first eccentric portion 77A and the center of the main shaft portion 77P. The bearing J is located between the outer peripheral surface of the second eccentric portion 77B and the inner surface of the eccentric shaft hole Y2 of the second external gear 72. The second eccentric portion 77B is supported by the bearing J so as to be rotatable.

[0131] The reducer 70 has a plurality of driven gears 79. The driven gears 79 are provided for each crankshaft 77. Each driven gear 79 is mounted on a portion of the main shaft portion 77P of the crankshaft 77 that protrudes upward relative to the eccentric shaft hole 82B of the second wall 82. Each driven gear 79 is in the shape of a roughly annular plate. The main shaft portion 77P is fixed to the center hole of each driven gear 79. Each driven gear 79 rotates integrally with the main shaft portion 77P. A plurality of teeth are formed on the outer peripheral surface of each driven gear 79. The plurality of teeth are arranged at equal intervals along the circumferential direction.

[0132] Input shaft

[0133] The reducer 70 has an input shaft 76. A portion of the input shaft 76 is located in a continuous first communicating hole formed by the input shaft hole 81A of the first wall 81 and the like. The input shaft 76 is cylindrical in shape. The input shaft 76 extends upward from the first communicating hole and reaches the lower end of the transmission shaft 25. The center axis Q of the input shaft 76 is substantially consistent with the center axis Q of the housing 75 and the transmission shaft 25. The upper end of the input shaft 76 is connected to the lower end of the transmission shaft 25. For example, the upper end of the input shaft 76 is fixed to the lower end of the transmission shaft 25 by a spline connection. The input shaft 76 rotates coaxially with the transmission shaft 25. In addition, the input shaft 76 is rotatably supported by a bearing F in the input shaft hole 82A of the second wall 82. Although not shown in the figure, the input shaft 76 is also rotatably supported by a bearing in the input shaft hole 81A of the first wall 81.

[0134] The speed reducer 70 includes a drive gear 78. The drive gear 78 is mounted on the input shaft 76. Specifically, the drive gear 78 is mounted on the portion of the input shaft 76 that protrudes upward relative to the first connecting hole. The drive gear 78 is in the shape of a roughly annular plate. The input shaft 76 is fixed to a hole in the center of the drive gear 78. The drive gear 78 rotates integrally with the input shaft 76. A plurality of teeth are formed on the outer peripheral surface of the drive gear 78. The plurality of teeth are arranged at equal intervals in the circumferential direction. Some of the plurality of teeth mesh with the teeth of the driven gear 79.

[0135] The boom swing mechanism 10 is configured as described above. In addition, all the components of the boom swing mechanism 10 of the present embodiment, except for the buffer portion 92 and the sealing members, are made of metal.

[0136] <Function 1 of the First Embodiment>

[0137] right Figure 3 The operation of the boom swing mechanism 10 shown in FIG. In the boom swing mechanism 10, when the output shaft 20B of the electric motor 20 rotates, the transmission shaft 25 and the input shaft 76 of the speed reducer 70 rotate along with the output shaft 20B. Rotation of the input shaft 76 of the speed reducer 70 rotates the drive gear 78 and the driven gear 79. Furthermore, rotation of the driven gear 79 rotates the crankshaft 77. The crankshaft 77 transmits its input rotation to the first and second external gears 71 and 72 via the first and second eccentric portions 77A and 77B. The first and second external gears 71 and 72 swing and rotate due to the forces from the first and second eccentric portions 77A and 77B. Specifically, the first external gear 71 rotates around the center axis Q of the input shaft 76 and the transmission shaft 25 while swinging, alternating the circumferential range of engagement with the teeth 75B of the housing 75. The second external gear 72 operates similarly to the first external gear 71. The above-mentioned actions of the first external gear 71 and the second external gear 72 drive the rotation of the housing 75. If the housing 75 rotates, the output wall 32 fixed to the housing 75 rotates together with the housing 75. That is, the output wall 32 receives the torque from the reducer 70 and rotates around the central axis Q of the transmission shaft 25. In addition, the rotation speed of the housing 75 and the output wall 32 is reduced at a predetermined ratio relative to the rotation speed of the output shaft 20B of the electric motor 20. That is, the reducer 70 amplifies and outputs the torque output by the output shaft 20B of the electric motor 20. If the output wall 32 rotates, the facing wall 53 connected to the output wall 32 via the connecting member 90 rotates. The facing wall 53 rotates around the central axis Q of the transmission shaft 25. If the facing wall 53 rotates, the base wall 534 of the boom 530 rotates together with the intermediate wall 57. In addition, the boom body 531 rotates. Through such a series of force transmissions, as Figure 2As shown by arrow P2 , the boom 530 swings left and right around the output shaft 20B of the electric motor 20 .

[0138] In the boom swing mechanism 10, the transmission shaft 25, the electric motor 20, the speed reducer 70, and the output member 30 constitute a drive device. Furthermore, the center axis Q of the transmission shaft 25 constitutes the rotation center axis of the drive device. In the drive device, the electric motor 20 is the driving source of the drive device. As described above, in the drive device, as the electric motor 20 is driven, the output member 30 outputs a torque centered on the rotation center axis. The swing wall 50 connected to the output member 30 is connected to the front part 520A of the mother machine via the pin 28 and the drive device in a manner that can rotate around the rotation center axis. Furthermore, as described above, the swing wall 50 receives the torque from the drive device and rotates around the rotation center axis.

[0139] <Function 2 of the First Embodiment>

[0140] The functions of the pin 28 and the contact wall 54 will be described. Figure 1 During the excavation work performed by the excavator 500 shown, the bucket 550 collides with the excavation object. When the bucket 550 collides with the excavation object, the impact of the excavation object as a reaction to the collision is transmitted to the boom 530 via the arm 540. The direction of the load acting on the boom 530 due to such an impact is various. For example, Figure 1 As shown by the arrow P1, the direction of the load acting on the boom 530 is sometimes the direction of rotating the boom 530 up and down. Figure 2 As shown by the arrow P2, the direction of the load acting on the boom 530 is sometimes the direction that causes the boom 530 to rotate left and right. If the boom 530 is subjected to a load in the up-down direction, the left-right direction, or a direction including the up-down and left-right directions, the boom 530 will move in the direction in which the load is received. In the structure of this embodiment, such movement of the boom 530 is transmitted to the mother machine 520 via the first path. Figure 3 As shown, the first path is the path between the intermediate wall 57 of the swinging wall 50, the contact wall 54, the pin 28, and the mother machine 520. Specifically, when the boom body 531 and the base wall 534 move in response to the load acting on the boom 530, the intermediate wall 57 of the swinging wall 50 moves accordingly. Furthermore, because the contact wall 54 of the swinging wall 50 contacts the pin 28, the movement of the intermediate wall 57 is transmitted to the pin 28 via the contact wall 54. Furthermore, the outer peripheral surface of the pin 28 collides with the inner surface of the first through-hole 520H of the mother machine front portion 520A. In this way, the load acting on the boom 530 is transmitted to the mother machine 520. The mother machine 520 then bears this load.

[0141] The function of the buffer portion 92 of the connecting member 90 will be described. The boom 530 and the swing wall 50 can rotate left and right due to the load as described above. In this case, this movement can be transmitted to the reducer 70 through the second path described below. The second path is a path including the intermediate wall 57 of the swing wall 50, the facing wall 53, the connecting member 90, the output wall 32, and the housing 75 of the reducer 70. Here, the buffer portion 92 of the connecting member 90 is made of rubber. Therefore, when a force is transmitted from the facing wall 53 to the output wall 32, the buffer portion 92 attenuates the force input from the facing wall 53 and then transmits it to the output wall 32. In other words, the movement of the output wall 32 becomes smaller than the movement of the facing wall 53. Therefore, even if the load acting on the boom 530 is transmitted to the reducer 70 via the second path, the force becomes quite small.

[0142] <Effects of the First Embodiment>

[0143] (1-1) As described in the first function of the above embodiment, the structure of this embodiment allows the rotation of the output shaft 20B of the electric motor 20 to be transmitted to the boom 530 via the following transmission path. This transmission path is the path that passes through the electric motor 20, the transmission shaft 25, the speed reducer 70, the output member 30, and the swing wall 50 to reach the boom 530. Furthermore, by operating the output shaft 20B of the electric motor 20, power is transmitted along this path, thereby causing the boom 530 to swing left and right. In other words, according to this embodiment, a swing mechanism for the boom 530 driven by the electric motor 20 can be implemented. Furthermore, when implementing a swing mechanism for the boom 530 driven by the electric motor 20, by adopting a layout in which the electric motor 20 and the speed reducer 70 are arranged vertically with the front section 520A of the base machine interposed therebetween, as in this embodiment, the size of each component can be reduced, and the space around the front section 520A of the base machine can be effectively utilized. Consequently, the overall size of the boom swing mechanism 10 can be reduced.

[0144] (1-2) As described in the second function of the above embodiment, when an impact is applied to the boom 530 by the bucket 550, the impact is transmitted to the mother machine 520 via the contact wall 54 and the pin 28. And the mother machine 520 receives the impact. At this time, the mother machine 520 is formed in a state of absorbing the load acting on the boom 530. By absorbing the load by the mother machine 520, the load reaching the reducer 70 via the above-mentioned second path becomes smaller. Assuming that the load acting on the reducer 70 is large, in order to receive the load, it is necessary to increase the size of various components of the reducer 70, such as the column wall 83 or the bearings. As a result, the reducer 70 may be enlarged. According to the structure of this embodiment, as described above, since the load reaching the reducer 70 can be reduced, it is not necessary to increase the size of the various components of the reducer 70 in order to bear the load. Therefore, the enlargement of the reducer 70 can be suppressed.

[0145] (1-3) As described in the second effect of the above embodiment, when the boom 530 and the facing wall 53 of the swing wall 50 rotate left and right in response to the load acting on the boom 530, the connecting member 90 mitigates the movement of the facing wall 53 and transmits it to the output wall 32. Therefore, in the structure of this embodiment, the transmission of the left and right rotational movement acting on the facing wall 53 to the speed reducer 70 can be suppressed. As a result, due to this situation and the effect obtained by (1-2) above, the load transmitted to the speed reducer 70 becomes significantly smaller. Therefore, similar to (1-2) above, the size of the speed reducer 70 can be suppressed.

[0146] <Modifications of the First Embodiment>

[0147] The above embodiment can be modified and implemented as follows: The above embodiment and the following modified examples can be combined and implemented within the scope of no technical contradiction.

[0148] The washer W can be omitted. Furthermore, the third gap can be configured to exist over the entire range where the specific portion 53P of the facing wall 53 and the output wall 32 are opposite. Even in this case, since the lower end surface of the extended portion 54B of the contact wall 54 is supported by the upper surface of the front portion 520A of the mother machine, the swing wall 50 can still be maintained in the following position. The following position is a position where the specific portion 53P of the facing wall 53 and the output wall 32 are facing each other in a state where they are separated. Furthermore, by omitting the washer W and providing the third gap over the entire range where the specific portion 53P of the facing wall 53 and the output wall 32 are opposite, the following effect can be achieved. That is, when an impact is applied to the boom 530 by the bucket 550, even if the specific portion 53P of the facing wall 53 moves up and down together with the base wall 534 of the boom 530, the specific portion 53P is unlikely to come into contact with the output wall 32 due to the presence of the third gap in the axial direction. Therefore, when the specific portion 53P of the facing wall 53 moves up and down, direct transmission of load from the facing wall 53 to the output wall 32 is suppressed. Furthermore, loads acting on the facing wall 53 are less likely to be transmitted to the output wall 32. Furthermore, as described in the above embodiment, the dimension of the third gap in the axial direction is larger than the dimension of the first gap between the outer peripheral surface of the pin 28 and the inner surface of the first through-hole 520H of the front section 520A of the main machine in the radial direction. Therefore, when the facing wall 53 moves along with the base wall 534 in response to an impact on the boom 530, the pin 28 collides with the front section 520A of the main machine before colliding with the facing wall 53. Therefore, nearly all of the load acting on the boom 530 is absorbed by the main machine 520. As a result, the loads reaching the output wall 32 and the speed reducer 70 can be significantly reduced. Similar to (1-2) and (1-3) above, this also helps prevent the speed reducer 70 from becoming larger.

[0149] The material of the buffer portion 92 of the connecting member 90 is not limited to the examples in the above embodiment. For example, the buffer portion 92 may also be made of resin. Similarly to the buffer portion 92, the material of the base portion 91 of the connecting member 90 is not limited to the examples in the above embodiment. The materials of the buffer portion 92 and the base portion 91 can be any material as long as they satisfy the following relationship: the elastic modulus of the buffer portion 92 is lower than the elastic modulus of the base portion 91.

[0150] The structure of the connecting member 90 is not limited to the examples in the above embodiment. For example, the buffer portion 92 may also be a polygonal square tube. Furthermore, the buffer portion 92 may be omitted. The connecting member 90 may be any structure capable of connecting the output wall 32 and the facing wall 53. In other words, the connecting member 90 may be any structure capable of transmitting the movement of the output wall 32 corresponding to the output of the speed reducer 70 to the facing wall 53.

[0151] The connecting member 90 can also be omitted. In this case, for example, the output wall 32 and the facing wall 53 can be formed as an integrally molded component. If the output wall 32 and the facing wall 53 are formed as an integrally molded component, the rotation of the reducer 70 can be transmitted to the boom 530 via this integrally molded component. In short, regardless of the presence of the connecting member 90, the structure from the output member 30 to the boom 530 can be configured so that the rotation of the reducer 70 is transmitted to the boom 530. With this structure, the boom 530 can be swung left and right using the driving force of the electric motor 20 and the power of the reducer 70. In other words, regardless of the presence of the connecting member 90, it is sufficient to connect the electric motor 20 and the reducer 70 via the transmission shaft 25, and the output member 30, which rotates in response to the power of the reducer 70, is connected to the boom 530. Furthermore, even without the connecting member 90, the presence of the pin 28 and the contact wall 54 can reduce the load transmitted from the boom 530 to the reducer 70 when an impact is applied to the boom 530. As will be described later, the pin 28 and the contact wall 54 are not essential. That is, the pin 28 and the contact wall 54 may be omitted in addition to omitting the connecting member 90 .

[0152] The structure of the output member 30 is not limited to the example in the above embodiment. For example, if the shape of the buffer portion 92 in the connecting member 90 is modified as in the above-described modification, the shape of the second through-hole 32H can be modified accordingly. The output member 30 can be configured to receive power from the speed reducer 70 and rotate about the central axis Q of the transmission shaft 25.

[0153] The structure of the swinging wall 50 is not limited to the example of the above embodiment. The swinging wall 50 only needs to be configured to transmit the power of the speed reducer 70 transmitted from the output member 30 to the boom 530. For example, similar to the above-mentioned modification of the output member 30, when the shape of the buffer portion 92 in the connecting member 90 is changed, the shape of the third through-hole 53H in the facing wall 53 can be changed accordingly. The guide wall 59 can also be omitted from the swinging wall 50. In addition, when the output wall 32 and the facing wall 53 are provided as an integrally molded part, as in the above-mentioned modification, the facing wall 53 can be omitted, or the swinging wall 50 as a whole wall portion can be eliminated.

[0154] As an example of modifying the structure of the swing wall 50, the shape of the contact wall 54 can be modified. The contact wall 54 only needs to be fixed to the boom 530 and configured to contact the pin 28 as the boom 530 moves when an impact is applied to the boom 530. If the contact wall 54 is configured to meet these conditions, when an impact is applied to the boom 530, the contact wall 54 can transmit the impact to the mother machine 520 via the pin 28.

[0155] The contact wall 54 is not essential. Even without the contact wall 54, it is sufficient as long as the electric motor 20 and the reducer 70 are connected by the transmission shaft 25, and the output member 30 that receives the power of the reducer 70 and rotates is connected to the boom 530. If this is the structure, as described above, the boom 530 can be swung left and right by the driving force of the electric motor 20. In addition, in the case of omitting the contact wall 54, if a connecting member 90 having a buffer portion 92 is used, or a structure having a third gap is used, then as described above, the load input from the boom 530 to the reducer 70 when an impact is applied to the boom 530 can be reduced. On the basis of omitting the contact wall 54, either or both of the connecting member 90 having the buffer portion 92 and the third gap can also be omitted.

[0156] The restriction member C for restricting the circumferential movement of the pin 28 is not essential.

[0157] The structure of the pin 28 is not limited to the example in the above embodiment. For example, the pin 28 may also have a polygonal, square, cylindrical shape. As long as the pin 28 is cylindrical with the transmission shaft 25 disposed therein and is disposed within the first through-hole 520H of the master machine 520 along with the transmission shaft 25, the pin 28 can be configured to meet these conditions. If the pin 28 is configured to meet these conditions, the pin 28 can transmit the load from the contact wall 54 to the master machine 520.

[0158] The pin 28 may be omitted. As with the modified example of the contact wall 54 , regardless of the presence or absence of the pin 28 , any structure may be employed in which the boom 530 can be swung left and right by the driving force of the electric motor 20 .

[0159] The structure of the speed reducer 70 is not limited to the example in the above embodiment. The speed reducer 70 may be any structure capable of reducing the rotational speed of the output shaft 20B of the electric motor 20 and outputting the reduced speed. Furthermore, a mechanism other than the speed reducer 70 may be employed as a transmission. The speed reducer may be any structure capable of changing the rotational speed of the electric motor 20 input via the transmission shaft 25 and outputting the reduced speed.

[0160] The structure of the first retaining member 41 is not limited to the example in the above embodiment. The first retaining member 41 can be configured to retain the electric motor 20 in an appropriate position and posture. The same applies to the second retaining member 42. In other words, the second retaining member 42 can be configured to retain the speed reducer 70 in an appropriate position and posture. Furthermore, the so-called appropriate position and posture refers to a position and posture that allows the rotation of the output shaft 20B of the electric motor 20 to be transmitted to the input shaft 76 of the speed reducer 70 via the transmission shaft 25.

[0161] The shape of the front part 520A is not limited to that of the above embodiment. The front part 520A only needs to have a through hole in which the transmission shaft 25 is disposed and to be able to mount the electric motor 20 and the speed reducer 70 on one side and the other side across the through hole.

[0162] The overall structure of the boom swing mechanism 10 is not limited to the example of the above-mentioned embodiment. For example, the extension direction of the central axis Q of the transmission shaft 25 can be slightly inclined relative to the upward direction. The central axis Q of the transmission shaft 25 only needs to extend along the upper and lower sides of the mother machine as a whole. For example, it may be inclined relative to the upward direction within a range of about 15 degrees. The boom swing mechanism 10 only needs to connect the output shaft of the electric motor and the input shaft of the reducer through the transmission shaft arranged in the first through hole of the mother machine, and the output member that rotates by receiving power from the reducer rotates the swing wall 50 and the boom. The materials of the various components of the boom swing mechanism 10 can also be changed according to the example of the above-mentioned embodiment. Each component can be made of an appropriate material so that the boom 530 can be swung by the driving force of the electric motor 20.

[0163] In the above embodiment, the boom swing mechanism 10 includes the main machine 520 as a structural component. However, in the excavator 500, the main machine 520 may be a separate, integral structural component from the boom swing mechanism 10. In other words, it is not essential that the boom swing mechanism 10 includes the main machine 520. The same applies to the boom 530. In other words, in the excavator 500, the boom 530 may be a separate, integral structural component from the boom swing mechanism 10. It is not essential that the boom swing mechanism 10 includes the boom 530 as a structural component.

[0164] The construction machine to which the boom swing mechanism 10 , which is an electric actuator, is applied is not limited to the excavator 500 .

[0165] In the above embodiment, a portion composed of multiple objects can be integrated into the multiple objects. Conversely, a portion composed of a single object can be divided into multiple objects. Whether integrated or not, the purpose of the present invention can be achieved. For example, the wall portions formed as an integral part in the above embodiment can be pre-formed separately and then integrated using bolts or the like. Furthermore, in the above embodiment, the wall portions fixed with bolts can also be pre-formed integrally with each other.

[0166] The technical ideas that can be grasped from the above-mentioned embodiments and modifications are described.

[0167] [1] A boom swing mechanism of a construction machine comprises: a base machine having a first through hole; an electric motor mounted on the base machine; a transmission located on the opposite side of the electric motor across the first through hole and configured to change the rotational speed of an output shaft of the electric motor; a transmission shaft disposed in the first through hole and connected to the output shaft of the electric motor and the input shaft of the transmission; an output member receiving power from the transmission and rotating about a central axis of the transmission shaft; and a boom connected to the output member.

[0168] The boom swing mechanism of the construction machine described in [2][1] comprises: a pin in a cylindrical shape, in which the transmission shaft is arranged, and which is arranged in the first through hole together with the transmission shaft; and a contact wall fixed to the boom and in contact with the pin.

[0169] [3] The boom swing mechanism of a construction machine described in [1] or [2], wherein the output member has a second through-hole, and the boom swing mechanism comprises: a facing wall fixed to the boom and having a third through-hole at a position facing the second through-hole; and a connecting member connecting the output member and the facing wall. The connecting member comprises: a base disposed within the second through-hole and the third through-hole; and a buffer portion having a cylindrical shape with the base disposed therein, and disposed together with the base within the second through-hole and the third through-hole, and having a smaller buffer coefficient than that of the base.

[0170] [4] The boom swing mechanism of a construction machine as described in any one of [1] to [3] comprises: a relative wall fixed to the boom and opposite to the output member; and a connecting member connecting the relative wall and the output member, with a gap between the relative wall and the output member.

[0171] <Second embodiment>

[0172] Below, use Figures 5 and 6 A second embodiment of a construction machine and an electric actuator for a construction machine will be described. It should be noted that the drawings may sometimes show structural components in an enlarged manner to facilitate understanding. In addition, the dimensional ratios of structural components may sometimes differ from the actual dimensional ratios or dimensional ratios in other drawings. Figure 5 and Figure 6 In, with Figures 1 to 4 Parts that perform the same or substantially the same function are marked with Figures 1 to 4 In the following description, the description of the parts that overlap with those of the first embodiment may be appropriately omitted or simplified.

[0173] Overall Structure

[0174] like Figure 5 As shown, an excavator 600 as a construction machine has a lower body 602, an upper body 606 as a vehicle body, and a pair of travel devices 510. The upper body 606 is located on the side opposite to the ground relative to the lower body 602. In this embodiment, up and down, front and back, left and right are defined based on the excavator 600. That is, when viewed from the lower body 602, the direction in which the upper body 606 is located is the upper direction, and the opposite direction is the lower direction. In addition, a specific direction among the directions orthogonal to the upper direction is the front direction, and the opposite direction is the rear direction. Moreover, one of the directions orthogonal to both the upper direction and the front direction is the left direction, and the other is the right direction. Hereinafter, the front direction and the rear direction are collectively referred to as the X direction, the left direction and the right direction are collectively referred to as the Y direction, and the upper direction and the lower direction are collectively referred to as the Z direction. It should be noted that in Figure 5 6. In the figure, some components of the excavator 600 are shown in cross section for convenience of description.

[0175] The lower body 602 has a rectangular parallelepiped shape, for example. It houses various mechanisms, devices, and components required to operate the excavator 600. A pair of travel devices 510 are located on either side of the lower body 602. The travel devices 510 include crawler tracks and other components for travel. The travel devices 510 enable the excavator 600 to move.

[0176] like Figure 5As shown, the upper body 606 has a accommodating portion 607, a boarding portion 608 and a support wall portion 609. The outer shape of the accommodating portion 607 is a rectangular parallelepiped. The interior of the accommodating portion 607 is hollow. Similar to the lower body 602, the accommodating portion 607 accommodates various mechanisms, devices and components. For example, a counterweight 629 is arranged at the rear end of the accommodating portion 607. The counterweight 629 is a counterweight for achieving weight balance of the excavator 600. The lower surface of the accommodating portion 607 is opposite to the lower body 602. The boarding portion 608 is located on the upper side relative to the accommodating portion 607. The boarding portion 608 includes a seat for the operator, etc. The support wall portion 609 protrudes from the front surface of the accommodating portion 607 toward the front side. The support wall portion 609 is fixed to the accommodating portion 607. The support wall portion 609 spans the center of the accommodating portion 607 in the Z direction. As shown Figure 6 As shown, the support wall portion 609 spans the center of the accommodating portion 607 in the Y direction. Figure 6 In FIG, the illustration of the boarding section 608 is omitted. Figure 5 As shown, the support wall portion 609 has a through hole 609A. The through hole 609A passes through the support wall portion 609 from top to bottom. The central axis of the through hole 609A extends approximately in the Z direction. The central axis of the through hole 609A will also be referred to as the rotation center axis 610V below. Figure 6 As shown, in the Y direction, the rotation center axis 610V is located approximately in the center of the accommodation portion 607.

[0177] <Slewing bearing>

[0178] like Figure 5 As shown, the excavator 600 has a slewing bearing 603. The slewing bearing 603 is located between the lower body 602 and the upper body 606. Figure 5 In FIG, the upper and lower widths of the slewing bearing 603 in the Z direction are exaggerated. Figure 6 As shown, the slewing bearing 603 has an annular inner ring 604, an annular outer ring 605, and a plurality of rolling elements. Figure 6Illustration of the rolling elements is omitted. The outer diameter of the inner ring 604 is smaller than the inner diameter of the outer ring 605. The central axis of the inner ring 604 is approximately aligned with the central axis of the outer ring 605. The inner ring 604 is radially inward of the outer ring 605, centered about its own central axis. The central axes of both the inner ring 604 and the outer ring 605 extend approximately in the Z direction. Hereinafter, the central axis of the inner ring 604 will be referred to as the bearing axis 603V. The bearing axis 603V is approximately centered within the housing 607 in both the X and Y directions. The plurality of rolling elements are, for example, balls. These rolling elements are located between the inner ring 604 and the outer ring 605. These rolling elements support the inner ring 604 and the outer ring 605 so that they can rotate relative to each other. As a result, the outer ring 605 can rotate relative to the inner ring 604 about the bearing axis 603V. The inner ring 604 is fixed to the lower body 602. The outer ring 605 is fixed to the housing portion 607 of the upper body 606. That is, the upper body 606 is rotatable about the bearing axis 603V relative to the lower body 602. The rear end of the outer ring 605 is located forward of the counterweight 629.

[0179] Although not shown in the figure, the rotary drive unit is located near the rotary bearing 603. The rotary drive unit includes an electric motor and a reducer that reduces and outputs the rotation speed of the electric motor. The electric motor can rotate in both forward and reverse directions. As the electric motor can rotate in both forward and reverse directions, the rotary drive unit can output torque in both forward and reverse directions. The torque output by the rotary drive unit drives the outer ring 605 to rotate relative to the inner ring 604. In addition, the upper body 606 rotates left and right relative to the lower body 602. As described above, the upper body 606 is supported by the rotary bearing 603 so as to be able to rotate relative to the lower body 602. In addition, the bearing axis 603V constitutes the center axis (second rotation center axis) of the rotation of the upper body 606 relative to the lower body 602.

[0180] <Excavator>

[0181] like Figure 5As shown, as an excavator, the excavator 600 includes a boom 530, an arm 540, and a bucket 550. The structures of the boom 530, the arm 540, and the bucket 550 are basically the same as those of the first embodiment. That is, the boom 530 includes a base wall 534, a connecting shaft 532, and a boom body 531. The base wall 534 is located on the front side relative to the upper body 606. The base wall 534 is fixed to the swing bracket 610 described later. The base wall 534 can be of any shape as long as it can be fixed to the swing bracket 610. The connecting shaft 532 connects the base wall 534 and the boom body 531. One end of the boom body 531 is fixed to the connecting shaft 532. The boom body 531 can rotate up and down with the connecting shaft 532 as the rotation center. The arm 540 is connected to the other end of the boom body 531. The arm 540 is rotatable relative to the boom body 531 about the connection point with the boom body 531. The bucket 550 is connected to the front end of the arm 540 on the opposite side of the boom body 531. The bucket 550 is rotatable relative to the arm 540 about the connection point with the arm 540.

[0182] <Boom swing mechanism>

[0183] The excavator 600 has a boom swing mechanism 600A. Figure 6 As shown by arrow 600V, the boom swing mechanism 600A is a mechanism for swinging the boom 530 left and right relative to the upper body 606. The boom swing mechanism 600A constitutes an electric actuator.

[0184] like Figure 5 As shown, the boom swing mechanism 600A has a swing bracket 610. The swing bracket 610 is located between the receiving portion 607 of the upper body 606 and the boom 530. The swing bracket 610 includes an upper wall 611, a lower wall 612, and a connecting wall 613.

[0185] The upper wall 611 is located on the upper side relative to the support wall portion 609. The upper wall 611 extends from the front portion of the support wall portion 609 toward the front side. The front end of the upper wall 611 reaches the front side further than the front surface of the support wall portion 609. The upper wall 611 is a plate-shaped plate with thickness at the top and bottom. Figure 6 As shown, when the upper wall 611 is viewed from above, the upper wall 611 is a pentagon. That is, when the upper wall 611 is viewed from above, the upper wall 611 is a structure formed by connecting a quadrilateral first part and a triangular second part. The second part is located on the rear side relative to the first part. Figure 5As shown, near the joint between the first and second parts, a through-hole 611A extends vertically. The central axis of through-hole 611A extends generally in the Z direction. The central axis of through-hole 611A is substantially aligned with the rotational axis 610V. As described above, the rotational axis 610V is the central axis of through-hole 609A in support wall 609. Furthermore, the diameter of through-hole 611A is smaller than the diameter of through-hole 609A in support wall 609.

[0186] like Figure 5 As shown, the connecting wall 613 protrudes downward from the lower surface of the upper wall 611. For example, the connecting wall 613 is an integrally formed part with the upper wall 611. Figure 6 As shown, the connecting wall 613 is located at the front portion of the upper wall 611. The connecting wall 613 extends along the edge of the upper wall 611. Figure 5 As shown, the base wall 534 of the boom 530 is fixed to the surface of the connecting wall 613 opposite to the surface facing the support wall portion 609. In addition, the Z-direction dimension of the connecting wall 613 is substantially the same as the Z-direction dimension of the support wall portion 609 of the upper body 606.

[0187] The lower wall 612 is located below the connecting wall 613. The lower wall 612 has approximately the same shape and dimensions as the upper wall 611. When viewed from above, the sides of the pentagon of the lower wall 612 overlap with the sides of the pentagon of the upper wall 611. Furthermore, the central axis of the through-hole 612A in the lower wall 612 is approximately aligned with the central axis of rotation 610V. For example, the lower wall 612 is integrally formed with the connecting wall 613.

[0188] The boom swing mechanism 600A has a pin 620. The pin 620 is arranged in the through hole 609A of the support wall portion 609. The pin 620 is cylindrical. The central axis of the pin 620 extends approximately in the Z direction. The central axis of the pin 620 is approximately consistent with the rotation center axis 610V. The diameter of the pin 620 is smaller than the diameter of the through hole 609A of the support wall portion 609. In addition, there is a gap between the outer surface of the pin 620 and the inner surface of the through hole 609A of the support wall portion 609. Figure 5 6. In FIG. 6, the gap between the inner surface of the through hole 609A and the outer surface of the pin 620 is exaggerated. The pin 620 is rotatably supported by the inner surface of the through hole 609A. The pin 620 is rotatable around the rotation center axis 610V.

[0189] The pin 620 passes through the through-hole 611A of the upper wall 611 and the through-hole 612A of the lower wall 612 of the swing bracket 610. The upper end of the pin 620 is located above the upper surface of the upper wall 611. In addition, the lower end of the pin 620 is located below the lower surface of the lower wall 612. Moreover, in the Z direction, the lower end of the pin 620 is located below the lower surface of the accommodating portion 607 of the upper body 606. The diameter of the pin 620 is substantially the same as the diameter of the through-hole 611A of the upper wall 611 and the through-hole 612A of the lower wall 612. The pin 620 is fixed to the upper wall 611 and the lower wall 612. Therefore, when the pin 620 rotates around the rotation center axis 610V, the upper wall 611 and the lower wall 612 rotate integrally with the pin 620. In this manner, the swing bracket 610 is connected to the support wall portion 609 via the pin 620 so as to be rotatable about the rotation center axis 610V (first rotation center axis).

[0190] <Drive device>

[0191] like Figure 5 As shown, the boom swing mechanism 600A includes a drive device 615. The drive device 615 is entirely located inside the housing portion 607. The drive device 615 includes an electric motor 616, a speed reducer 617, and a transmission shaft 618.

[0192] The electric motor 616 is the driving source of the drive device 615. The electric motor 616 includes a housing 616A and an output shaft 616B. The electric motor 616 is operated by power supplied from a battery (not shown). The housing 616A is located inside the housing 607. The housing 616A is attached to the inner wall of the housing 607. The housing 616A is located forward of the slewing bearing 603. In the Y direction, the housing 616A is approximately centered within the housing 607. The housing 616A has a cylindrical outer shape. The central axis of the housing 616A extends approximately in the Z direction. The central axis of the housing 616A is approximately parallel to the aforementioned rotational axis 610V of the swing bracket 610. The output shaft 616B protrudes downward from the housing 616A. The output shaft 616B is cylindrical in shape. The central axis of the output shaft 616B is approximately aligned with the central axis of the housing 616A. The output shaft 616B is rotatable relative to the housing 616A. The output shaft 616B rotates about its own central axis and can rotate in both forward and reverse directions according to the power supplied to the housing 616A.

[0193] The reducer 617 is located below the electric motor 616. The reducer 617 is located inside the housing 607. The reducer 617 is mounted on the inner wall of the housing 607. The reducer 617 has a cylindrical shape. The outer diameter of the reducer 617 is approximately the same as the outer diameter of the housing 616A of the electric motor 616. The central axis of the reducer 617 is approximately the same as the central axis of the output shaft 616B of the electric motor 616. The reducer 617 is connected to the output shaft 616B of the electric motor 616. Furthermore, the torque of the output shaft 616B of the electric motor 616 is input to the reducer 617. The reducer 617 amplifies and outputs the torque of the output shaft 616B of the electric motor 616 at a predetermined ratio. The reducer 617 is, for example, an eccentric oscillating gear type reducer or a planetary gear type reducer. The reducer 617 can be any type of reducer as long as it can amplify and output the torque from the electric motor 616.

[0194] The transmission shaft 618 is located on the lower side relative to the reducer 617. A portion of the transmission shaft 618 is located inside the accommodating portion 607. The remaining portion of the transmission shaft 618 protrudes downward from the lower surface of the accommodating portion 607. The transmission shaft 618 is cylindrical. The diameter of the transmission shaft 618 is smaller than the diameter of the reducer 617. The center axis of the transmission shaft 618 is roughly consistent with the center axis of the output shaft 616B of the electric motor 616. The transmission shaft 618 is connected to the reducer 617. The transmission shaft 618 receives torque from the reducer 617 and rotates around its own center axis. That is, when the center axis of the transmission shaft 618 is the rotation center axis 615V, the transmission shaft 618 and the drive device 615 output torque centered on the rotation center axis 615V.

[0195] The position of the drive device 615 in the X direction and the Y direction is described in detail. The position of the drive device 615 is determined in association with the rotation center axis 610V, which is the central axis of the through hole 609A of the support wall portion 609, and the bearing axis 603V, which is the central axis of rotation of the upper body 606. The direction in which the rotation center axis 610V is located when viewed from the bearing axis 603V is referred to as the first direction. The first direction of this embodiment is the forward direction. In addition, as Figure 6As shown, the portion of the outer ring 605 of the slewing bearing 603 that is closest to the center axis 610V in the first direction is referred to as a specific portion 603P. Specific portion 603P is the front end of the outer ring 605 of the slewing bearing 603. Furthermore, when the excavator 600 is viewed in the direction along the center axis 610V, the imaginary line segment connecting specific portion 603P and the center axis 610V is referred to as a specific line segment 603S. The drive unit 615 is positioned to satisfy the following first condition: when the excavator 600 is viewed in the direction along the center axis 610V, the rotation center axis 615V of the drive unit 615 is located on the specific line segment 603S.

[0196] Drive sprocket

[0197] like Figure 5 As shown, the boom swing mechanism 600A has a drive sprocket 621. The drive sprocket 621 is a driving member. The drive sprocket 621 is mounted on the transmission shaft 618. That is, the drive sprocket 621 is mounted on the accommodating portion 607 via the drive device 615. Figure 6 As shown, the drive sprocket 621 has a main body 621A and a plurality of teeth 621B. Figure 6 , only a portion of the plurality of teeth 621B is schematically shown. The main body 621A is annular. The central axis of the main body 621A is roughly consistent with the rotation center axis 615V. The transmission shaft 618 passes through the hole in the center of the main body 621A. The main body 621A is fixed to the transmission shaft 618. The main body 621A rotates integrally with the transmission shaft 618. In other words, the main body 621A receives torque from the drive device 615 and rotates around the rotation center axis 615V. The plurality of teeth 621B protrude from the outer peripheral surface of the main body 621A. The plurality of teeth 621B are arranged at equal intervals in the circumferential direction around the rotation center axis 615V. In addition, in the drive sprocket 621, the teeth 621B protrude from the outer peripheral surface of the main body 621A, which is equivalent to the drive sprocket 621 having teeth 621B on the outer peripheral surface of the main body 621A.

[0198] <Driven sprocket>

[0199] like Figure 5 As shown, the boom swing mechanism 600A has a driven sprocket 622. The driven sprocket 622 is a transmission member. The driven sprocket 622 is mounted on the pin 620. That is, the driven sprocket 622 is mounted on the swing bracket 610 via the pin 620. Figure 6 As shown, the driven sprocket 622 has a main body 622A and a plurality of teeth 622B. Figure 6, only a portion of the plurality of teeth 622B is schematically shown. The main body 622A is annular. The outer diameter of the main body 622A is larger than the outer diameter of the main body 621A of the driving sprocket 621. The central axis of the main body 622A is roughly consistent with the rotation center axis 610V. The pin 620 passes through the central hole of the main body 622A. The main body 622A is fixed to the pin 620. The main body 622A rotates integrally with the pin 620. That is, the main body 622A rotates around the rotation center axis 610V. The plurality of teeth 622B protrude from the outer peripheral surface of the main body 622A. The plurality of teeth 622B are arranged at equal intervals in the circumferential direction around the rotation center axis 610V. In addition, in the driven sprocket 622, the teeth 622B protrude from the outer peripheral surface of the main body 622A, which is equivalent to the driven sprocket 622 having teeth 622B on the outer peripheral surface of the main body 622A.

[0200] <Chain>

[0201] The boom swing mechanism 600A includes a chain 623. Chain 623 serves as a transmission mechanism. Chain 623 is wound around a drive sprocket 621 and a driven sprocket 622. Chain 623 meshes with teeth 621B of the drive sprocket 621 and teeth 622B of the driven sprocket 622. Chain 623 transmits the rotation of the drive sprocket 621 to the driven sprocket 622. Furthermore, chain 623 causes the drive sprocket 621 and the driven sprocket 622 to rotate in conjunction with each other.

[0202] <Function of the Second Embodiment>

[0203] In the boom swing mechanism 600A, when the output shaft 616B of the electric motor 616 rotates, the transmission shaft 618 rotates together with the output shaft 616B. Furthermore, when the transmission shaft 618 rotates, the drive sprocket 621 rotates. The rotation of the drive sprocket 621 rotates the drive chain 623 and the driven sprocket 622. When the driven sprocket 622 rotates, the swing bracket 610 rotates together with the pin 620. Furthermore, as the swing bracket 610 rotates, Figure 6 As shown by arrow 600V, the boom 530 swings left and right around the rotation center axis 610V.

[0204] <Effects of the Second Embodiment>

[0205] (2-1) As described in the operation of the above embodiment, in the excavator 600 of this embodiment, the boom 530 can be swung left and right using the electric motor 616 as a drive source.

[0206] As described in the first embodiment, a load can be input from the outside to the boom 530 due to the collision between the bucket 550 and the excavation object. This load is called a collision load. Figure 5As shown, in the excavator 600 of this embodiment, the collision load can be transmitted to the driven sprocket 622 via the swing bracket 610 and the pin 620. Furthermore, when the collision load is input, the driven sprocket 622 moves slightly accordingly. This movement of the driven sprocket 622 is absorbed by the chain 623 due to, for example, slight deflection. Therefore, the movement of the driven sprocket 622 is hardly transmitted to the drive sprocket 621 and the drive unit 615. In this way, the excavator 600 of this embodiment can suppress the collision load input to the boom 530 from reaching the drive unit 615. Therefore, similar to the first embodiment, the structure of this embodiment eliminates the need for a structure to withstand the collision load in the speed reducer 617 and the electric motor 616. This, for example, can prevent the speed reducer 617 from becoming larger.

[0207] (2-2) In this embodiment, a sprocket and a chain are used as a mechanism for transmitting the torque of the drive device 615 to the boom 530. The use of the sprocket and the chain allows the torque of the drive device 615 to be efficiently transmitted to the pin 620 and the boom 530 without causing any loss of torque due to the meshing of the sprocket teeth with the chain. Furthermore, as described in (2-1), the use of the chain allows the load reaching the driven sprocket 622 to be absorbed by deflection.

[0208] (2-3) In the structure of this embodiment, the outer diameter of the driven sprocket 622 is larger than the outer diameter of the driving sprocket 621. By adopting this sprocket size relationship, the torque of the driving device 615 can be converted into a large torque and transmitted to the pin 620 and the boom 530. Therefore, in the structure of this embodiment, the torque of the driving device 615 required to swing the boom 530 can be reduced.

[0209] (2-4) In this embodiment, the drive unit 615 and the drive sprocket 621 are arranged to satisfy the first condition. Specifically, the rotational axis 615V of the drive unit 615 and the drive sprocket 621 is located between the front end of the outer ring 605 of the slewing bearing 603 and the rotational axis 610V, which serves as the center axis of the driven sprocket 622. With this arrangement, the distance from the drive sprocket 621 to the driven sprocket 622 is shortened. Therefore, since the chain 623 wound around the drive sprocket 621 and the driven sprocket 622 can be shortened, the loss of force transmitted from the drive sprocket 621 to the driven sprocket 622 can be suppressed. In other words, force can be efficiently transmitted from the drive sprocket 621 to the driven sprocket 622.

[0210] <Modification of Second Embodiment>

[0211] The second embodiment can be modified and implemented as follows: The first embodiment to the second embodiment and the following modified examples can be combined and implemented within a range that does not technically conflict with each other.

[0212] The driving member is not limited to the examples in the above-mentioned embodiments. For example, the driving member may be an annular drive pulley centered on the rotation center axis 615V. That is, the driving member may be a structure without teeth formed on the outer circumference. When a drive pulley is used as the driving member, it is possible to consider using an annular driven pulley centered on the rotation center axis 610V as the transmitted member. Similar to the drive pulley, the driven pulley may be a structure without teeth formed on the outer circumference. When a drive pulley is used as the driving member and a driven pulley is used as the transmitted member, it is possible to consider using a belt wound around the drive pulley and the driven pulley as the transmitted member. When using such a drive pulley, driven pulley, and belt, when power is transmitted from the drive pulley to the driven pulley, the generation of noise and vibration can be suppressed. Furthermore, the driving member, the transmitted member, and the transmission mechanism are not limited to the pulleys and belts mentioned here. It is sufficient that the driving member, the transmitted member, and the transmission mechanism are configured to transmit power to each other. For example, the driving member, the transmitted member, and the transmission mechanism may also be configured as a series of gear mechanisms.

[0213] For example, Figure 7 As shown in FIG, the driving member, the transmitted member, and the transmission mechanism can also be constructed as a series of connecting rod mechanisms. Figure 7In the structure shown, the driving member is the driving link 630. The transmitted member is the driven link 632. The transmission mechanism is the transmission link 631, the first link shaft 633, and the second link shaft 634. The driving link 630, the driven link 632, and the transmission link 631 are each in the shape of a long strip. The first link shaft 633 and the second link shaft 634 are each in the shape of a cylindrical column. The first end of the driving link 630 is fixed to the transmission shaft 618 of the driving device 615. The driving link 630 rotates integrally with the transmission shaft 618. The second end of the driving link 630 is connected to the transmission link 631 via the first link shaft 633. Specifically, the first link shaft 633 is fixed to the second end of the driving link 630. The central axis of the first link shaft 633 extends approximately in the Z direction. The first link shaft 633 passes through the first end of the transmission link 631. The transmission link 631 and the first link shaft 633 are capable of relative rotation. The first connecting rod shaft 633 will not fall off from the driving link 630 and the transmission link 631. The second end of the transmission link 631 is connected to the driven link 632 via the second connecting rod shaft 634. Specifically, the second connecting rod shaft 634 passes through the second end of the transmission link 631. The central axis of the second connecting rod shaft 634 extends approximately in the Z direction. The transmission link 631 and the second connecting rod shaft 634 are able to rotate relative to each other. The second connecting rod shaft 634 is fixed to the first end of the driven link 632. The second connecting rod shaft 634 is prevented from falling off from the transmission link 631 and the driven link 632. The second end of the driven link 632 is fixed to the pin 620. The driven link 632 rotates integrally with the pin 620. In the above structure, when the transmission shaft 618 rotates, the driving link 630 rotates about the rotation center axis 615V. The rotation of the driving link 630 is transmitted to the driven link 632 via the transmission link 631. Furthermore, the driven link 632 rotates together with the pin 620 about the rotation center axis 610V. Furthermore, the swing bracket 610 and the movable arm 530 rotate together with the pin 620. Here, for example, other components can be arranged between the transmission shaft 618 of the drive device 615 and the pin 620. In order to avoid interference with such components and connect the transmission shaft 618 and the pin 620, a Figure 7 Such a link mechanism is also effective. In addition, when such a link mechanism is adopted, the number of link members constituting the link mechanism and the arrangement of each link member can be appropriately changed. Figure 7 In, with Figure 5 and Figure 6 Parts that perform the same or substantially the same function are marked with Figure 5 and Figure 6 In addition, Figure 6 Likewise, in Figure 7 The illustration of the boarding section 608 is omitted.

[0214] When the driving member and the transmitted member are annular, cylindrical, or columnar, the size relationship between the outer diameters of the driving member and the transmitted member is not limited to the examples in the above embodiment. For example, the outer diameters of the driving member and the transmitted member may be substantially the same.

[0215] The connection method between the drive member and the drive device 615 is not limited to the examples in the above embodiment. The drive member only needs to be mounted on a mating member to receive torque from the drive device 615 and be able to rotate about the rotational axis 615V of the drive device 615. For example, other components may be interposed between the drive member and the drive device 615. Depending on the connection method between the drive member and the drive device 615, the configuration of the drive member may vary from the examples in the above embodiment.

[0216] The connection method of the transmitted member and the swing bracket 610 is not limited to the example of the above-mentioned embodiment. For example, instead of the pin 620 passing through the lower wall 612, a columnar member for replacing the pin 620 can be installed on the lower surface of the lower wall 612. In addition, the transmitted member can be installed on the columnar member. The transmitted member can also be directly fixed to the lower surface of the lower wall 612. Depending on the connection method of the transmitted member and the swing bracket 610, etc., the configuration of the transmitted member can be changed from the example of the above-mentioned embodiment. The position of the transmitted member can be set by rotating around the rotation center axis 610V of the swing bracket 610.

[0217] The structure and arrangement of the swing bracket 610 are not limited to the examples in the above embodiment. Any configuration is sufficient as long as the swing bracket 610 is fixed to the boom 530 and connected to the vehicle body so as to be rotatable about the rotational axis 610V. For example, the shape of the upper wall 611 may be modified from the examples in the above embodiment.

[0218] The connection method of the swing bracket 610 and the vehicle body is not limited to the example of the above embodiment. As long as the swing bracket 610 is connected to the vehicle body so as to be rotatable around the rotation center axis 610V, the connection method is not limited.

[0219] The structure of the vehicle body supporting the swing bracket 610 is not limited to the example in the above embodiment. For example, the through hole 609A of the support wall portion 609 and the rotation center axis 610V may be offset from the center of the accommodating portion 607 in the Y direction. The position of the swing bracket 610 relative to the vehicle body can be changed depending on the structure of the vehicle body supporting the swing bracket 610, etc.

[0220] The location where the boom 530 is fixed to the swing bracket 610 is not limited to the example in the above embodiment, and the boom 530 may be fixed to any location on the swing bracket 610 .

[0221] The structure and arrangement of the slewing bearing 603 are not limited to the examples in the above embodiment. As long as the upper body 606 can be supported so as to be rotatable relative to the lower body 602, the structure and arrangement of the slewing bearing 603 are not limited.

[0222] The positional relationship between the bearing axis 603V and the rotation center axis 610V, as well as the specific portion, first direction, and specific line segment related to the first condition, can be changed from the above-described embodiment examples depending on the position of the through hole 609A, the configuration of the rotary bearing 603, and the like.

[0223] The structure and configuration of the drive unit 615 are not limited to the examples in the above-described embodiment. Any drive unit 615 mounted on the vehicle body, including the electric motor 616, and outputting torque centered about its central axis of rotation is sufficient. For example, the outer shape of the electric motor 616 may be modified from a cylindrical shape. For example, the reducer 617 and transmission shaft 618 may be omitted from the drive unit 615. Furthermore, the drive member may be directly mounted on the output shaft 616B of the electric motor 616. Furthermore, the drive unit 615 may be configured so that the central axis of the output shaft 616B of the electric motor 616 and the central axis of rotation of the torque outputted by the drive unit 615 to the outside of the vehicle body are located at different positions. Such a configuration is also feasible as long as a mechanism for changing the rotational direction of the electric motor 616 is included in the drive unit 615. The central axis of rotation of the torque outputted by the drive unit 615 may extend generally above and below the vehicle body; for example, it may be inclined within a range of approximately 15 degrees relative to the Z direction.

[0224] The first condition regarding the arrangement of the drive device 615 and the drive components is not limited to the example in the above embodiment. The first condition only requires that at least a portion of the drive components be located on the specific line segment 603S when the excavator 600 is viewed in a direction along the rotation center axis 610V. Arranging the drive components to satisfy this first condition achieves the same effects as those in (2-4) above.

[0225] The arrangement of the driving member does not necessarily have to satisfy the first condition. As an example of the case where the driving member is arranged regardless of the first condition, Figure 8 The boom swing mechanism 600B shown in FIG. As in the above embodiment, the boom swing mechanism 600B constitutes an electric actuator. Figure 8 In, with Figure 5 and Figure 6 Parts that perform the same or substantially the same function are marked with Figure 5 and Figure 6 In addition, Figure 6 Likewise, in Figure 8The illustration of the boarding section 608 is omitted.

[0226] Hereinafter, similarly to the above embodiment, the direction in which the rotation center axis 610V is located when viewed from the bearing axis 603V is referred to as the first direction. In addition, the direction opposite to the first direction is referred to as the second direction. Figure 8 In the example shown, the first direction is the front direction and the second direction is the rear direction.

[0227] exist Figure 8 In the illustrated boom swing mechanism 600B, the drive unit 615 and drive sprocket 621 are located rearward of the bearing axis 603V. Specifically, the drive unit 615 and drive sprocket 621 are located in the second direction relative to the bearing axis 603V. Furthermore, the drive unit 615 and drive sprocket 621 are located to the right of the outer ring 605 of the slewing bearing 603. The connection method between the drive unit 615 and drive sprocket 621 is the same as that described in the above embodiment.

[0228] exist Figure 8 In the boom swing mechanism 600B shown in FIG. 1 , the driven sprocket 622 is arranged at the same position as in the above embodiment. Figure 8 In the boom swing mechanism 600B shown, the outer diameter of the driven sprocket 622 is substantially identical to the outer diameter of the driving sprocket 621 .

[0229] The boom swing mechanism 600B includes a first intermediate shaft 627 and a second intermediate shaft 628. The first intermediate shaft 627 is located forward of the drive sprocket 621. Specifically, the first intermediate shaft 627 is located forward of the outer ring 605 of the slewing bearing 603. In the Y direction, the first intermediate shaft 627 is located approximately at the same position as the drive sprocket 621. The first intermediate shaft 627 is cylindrical. The central axis of the first intermediate shaft 627 extends approximately in the Z direction. That is, the central axis of the first intermediate shaft 627 is approximately parallel to the rotational axis 615V of the drive unit 615. The upper end surface of the first intermediate shaft 627 is fixed to the lower surface of the housing 607. In other words, the first intermediate shaft 627 is mounted in the housing 607.

[0230] The second intermediate shaft 628 is located to the left of the first intermediate shaft 627. When viewing the excavator 600 in the direction along the rotational axis 610V, the second intermediate shaft 628 is located on the imaginary line segment connecting the bearing axis 603V and the rotational axis 610V. That is, in the X and Y directions, the second intermediate shaft 628 is located at approximately the same position as the transmission shaft 618 in the above-described embodiment. Like the first intermediate shaft 627, the second intermediate shaft 628 is cylindrical. Its diameter is approximately the same as that of the first intermediate shaft 627. The central axis of the second intermediate shaft 628 extends generally in the Z direction. That is, the central axis of the second intermediate shaft 628 is approximately parallel to the rotational axis 615V of the drive unit 615. The upper end surface of the second intermediate shaft 628 is fixed to the lower surface of the housing 607. In other words, the second intermediate shaft 628 is mounted in the housing 607.

[0231] The boom swing mechanism 600B includes a first intermediate sprocket 625 and a second intermediate sprocket 626. Both the first and second intermediate sprockets 625 and 626 are intermediate components. The first intermediate sprocket 625 is mounted on a first intermediate shaft 627. Although not illustrated in detail, the first intermediate sprocket 625 has an annular main body, a first set of teeth protruding from the outer circumference of the main body, and a second set of teeth protruding from the outer circumference of the main body. For example, the first set of teeth is located at one end of the main body along the central axis of the main body. The second set of teeth is located at the other end of the main body along the central axis of the main body. The inner diameter of the main body is slightly larger than the diameter of the first intermediate shaft 627. The first intermediate shaft 627 extends through a hole in the center of the main body. The central axis of the main body is approximately aligned with the central axis of the first intermediate shaft 627. The main body is rotatable relative to the first intermediate shaft 627. The main body rotates about the first intermediate shaft 627 and its own central axis. Although not shown in the figure, a cylindrical member is attached to the side of the first intermediate shaft 627 opposite the lower surface of the housing 607, across from the first intermediate sprocket 625, to prevent the first intermediate sprocket 625 from falling out. Specifically, the first intermediate sprocket 625 is attached to the housing 607 and the vehicle body via the first intermediate shaft 627. When the first intermediate sprocket 625 is attached to the housing 607, the first set of teeth of the first intermediate sprocket 625 is positioned approximately in the same position in the Z direction as the teeth of the drive sprocket 621. The second set of teeth of the first intermediate sprocket 625 is positioned approximately in the Z direction as the second set of teeth of the second intermediate sprocket 626, described later.

[0232] The structure of the second intermediate sprocket 626 is identical to that of the first intermediate sprocket 625. Specifically, the second intermediate sprocket 626 includes an annular main body, and first and second tooth sets protruding from the outer circumference of the main body. The first and second tooth sets are located at positions separated along the central axis of the main body. A second intermediate shaft 628 extends through a hole in the center of the main body. The main body is rotatable relative to the second intermediate shaft 628. The main body rotates about the second intermediate shaft 628 and its own central axis. Furthermore, a cylindrical member is attached to the side of the second intermediate shaft 628 opposite the lower surface of the housing 607, across from the second intermediate sprocket 626, to prevent the second intermediate sprocket 626 from falling out. In other words, the second intermediate sprocket 626 is attached to the housing 607 and the vehicle body via the second intermediate shaft 628. When the second intermediate sprocket 626 is attached to the housing 607, the first tooth set of the second intermediate sprocket 626 is located approximately at the same position in the Z direction as the teeth of the driven sprocket 622.

[0233] The boom swing mechanism 600B includes a first chain 623A, a second chain 623B, and a third chain 623C. The first chain 623A, the second chain 623B, and the third chain 623C constitute a transmission mechanism.

[0234] The first chain 623A is wound around the drive sprocket 621 and the first set of teeth of the first intermediate sprocket 625. The first chain 623A meshes with the teeth of the drive sprocket 621 and the teeth of the first set of teeth of the first intermediate sprocket 625. The first chain 623A transmits the rotation of the drive sprocket 621 to the first intermediate sprocket 625. In other words, the first chain 623A causes the drive sprocket 621 and the first intermediate sprocket 625 to rotate in conjunction with each other.

[0235] The second chain 623B is wound around the second set of teeth of the first intermediate sprocket 625 and the second set of teeth of the second intermediate sprocket 626. The second chain 623B meshes with the teeth of the first intermediate sprocket 625 and the teeth of the second intermediate sprocket 626. The second chain 623B transmits the rotation of the first intermediate sprocket 625 to the second intermediate sprocket 626. In other words, the second chain 623B causes the first intermediate sprocket 625 and the second intermediate sprocket 626 to rotate in conjunction with each other.

[0236] The third chain 623C is wound around the first set of teeth of the second intermediate sprocket 626 and the driven sprocket 622. The third chain 623C meshes with the teeth of the first set of teeth of the second intermediate sprocket 626 and the teeth of the driven sprocket 622. The third chain 623C transmits the rotation of the second intermediate sprocket 626 to the driven sprocket 622. In other words, the third chain 623C causes the second intermediate sprocket 626 and the driven sprocket 622 to rotate in conjunction with each other.

[0237] exist Figure 8In the boom swing mechanism 600B shown in FIG. 1 , when the driving device 615 outputs torque, the driving sprocket 621, the first intermediate sprocket 625, the second intermediate sprocket 626, and the driven sprocket 622 rotate in conjunction with the torque. Furthermore, when the driven sprocket 622 rotates, the swing bracket 610 and the pin 620 rotate together. Furthermore, as the swing bracket 610 rotates, as shown in FIG. 1 , the swing bracket 610 rotates. Figure 8 As shown by arrow 600W, the boom 530 swings left and right around the rotation center axis 610V.

[0238] In adopting Figure 8 In the case of the boom swing mechanism 600B shown, the drive unit 615 and drive sprocket 621 can be positioned as far back as possible within the excavator 600. In this case, the weight of the excavator 600 shifts the weight of the drive unit 615 and drive sprocket 621 rearward. In this case, even if the weight of the counterweight 629 located at the rear end of the accommodating portion 607 is reduced, the weight of the excavator 600 can still be balanced. This allows for a lighter counterweight 629, which contributes to a reduction in the overall weight of the excavator 600.

[0239] exist Figure 8 In the boom swing mechanism 600B shown, the number and position of the intermediate sprockets between the driving sprocket 621 and the driven sprocket 622 are not limited to Figure 8 The number and position of the intermediate sprockets can be appropriately determined so that power can be smoothly transmitted from the driving sprocket 621 to the driven sprocket 622.

[0240] The connection mode of the intermediate sprocket relative to the vehicle body is not limited to Figure 8 An appropriate connection method can be designed so that the intermediate sprocket can rotate around a central axis parallel to the rotational central axis 615V of the driving device 615.

[0241] about Figure 8 The structures of the boom swing mechanism 600B shown, the driving member, the transmitted member, the intermediate member and the transmission mechanism are not limited to the above examples. As long as the driving member, the transmitted member, the intermediate member and the transmission mechanism can transmit the torque of the driving device 615 to the swing bracket 610, it will suffice. For example, as the driving member, the transmitted member and the intermediate member, a pulley without teeth formed on the outer peripheral surface can be used instead of a sprocket. In the case of using a pulley as the driving member, the transmitted member and the intermediate member, a belt can be used as a transmission mechanism. The driving member, the transmitted member, the intermediate member and the transmission mechanism can also be composed of a connecting rod mechanism or a gear mechanism.

[0242] In excavator 600, slewing bearing 603 is not essential. Specifically, depending on the structure of excavator 600, upper body 606 may not be able to swivel relative to lower body 602, and upper body 606 and lower body 602 may be integrally formed. In this case, upper body 606 and lower body 602 constitute the vehicle body. That is, the vehicle body is not limited to the example in the above embodiment.

[0243] The construction machine to which the boom swing mechanisms 600A and 600B, which are electric actuators, are applied is not limited to the excavator 600 .

[0244] In the above embodiment, various mechanisms can be used to fix the two members. Examples of the mechanism to fix the two members include bolt fastening, welding, integral molding, spline connection, and the like.

[0245] In the above embodiment, a portion composed of multiple objects may be integrated into the multiple objects, and conversely, a portion composed of one object may be divided into multiple objects. Regardless of integration or not, it is sufficient as long as the purpose of the present invention can be achieved.

[0246] <Third embodiment>

[0247] Below, use Figure 9 A third embodiment of a construction machine and an electric actuator for a construction machine will be described. It should be noted that the drawings may sometimes show structural components in an enlarged manner to facilitate understanding. In addition, the dimensional ratios of structural components may sometimes differ from the actual dimensional ratios or dimensional ratios in other drawings. Figure 9 In, with Figures 1 to 8 Parts that perform the same or substantially the same function are marked with Figures 1 to 8 In the following description, the description of the parts that overlap with those of the first and second embodiments will be appropriately omitted or simplified.

[0248] Overall Structure

[0249] like Figure 9 As shown, an excavator 650 as a construction machine has a lower body 602, an upper body 653 as a vehicle body, a pair of travel devices 510, and a slewing bearing 603. The structures of the lower body 602, the pair of travel devices 510, and the slewing bearing 603 are the same as those in the second embodiment. Therefore, their description is omitted. The upper body 653 will be described later. With respect to the lower body 602, the upper body 653 is located on the side opposite to the ground. In addition, in this embodiment, up, down, left, right, front and back are defined in the same way as in the second embodiment. Figure 9 In FIG. 6 , for convenience of explanation, some components of the excavator 650 are shown in cross section.

[0250] The upper body 653 includes a accommodating portion 607, a boarding portion 608, and a support wall portion 654. The structures of the accommodating portion 607 and the boarding portion 608 are the same as those of the second embodiment. The support wall portion 654 protrudes forward from the front surface 607F of the accommodating portion 607. The support wall portion 654 is fixed to the front surface 607F of the accommodating portion 607. The support wall portion 654 spans the center of the accommodating portion 607 in the Y direction. The support wall portion 654 has a through hole 654A. The through hole 654A extends vertically through the support wall portion 654. The central axis of the through hole 654A extends approximately in the Z direction.

[0251] As an excavating machine, excavator 650 includes a boom 530, an arm 540, and a bucket 550. Boom 530, arm 540, and bucket 550 are located forward relative to upper body 653. The structures of boom 530, arm 540, and bucket 550 are the same as those of the second embodiment. Therefore, their description will be omitted.

[0252] <Boom swing mechanism>

[0253] The excavator 650 includes a boom swing mechanism 650A. The boom swing mechanism 650A is a mechanism for swinging the boom 530 left and right relative to the upper body 653. The boom swing mechanism 650A constitutes an electric actuator.

[0254] The boom swing mechanism 650A includes a swing bracket 665. In the X direction, the swing bracket 665 is located between the housing 607 of the upper body 653 and the boom 530. Specifically, in the X direction, the swing bracket 665 is located approximately at the same position as the support wall 654. The swing bracket 665 is plate-shaped with thickness at its top and bottom. The base wall 534 of the boom 530 is fixed to the front end of the swing bracket 665.

[0255] The boom swing mechanism 650A includes a drive device 660 . The drive device 660 is located below the swing bracket 665 . The drive device 660 includes an electric motor 661 , a speed reducer 662 , and an output member 663 .

[0256] The electric motor 661 includes a housing 661A and an output shaft 661B. The electric motor 661 operates based on the power supply from a battery (not shown). The housing 661A is located on the lower side relative to the support wall portion 654 of the upper body 653. The housing 661A has a cylindrical outer shape. The central axis of the housing 661A extends approximately in the Z direction. The output shaft 661B protrudes upward from the housing 661A. The output shaft 661B is cylindrical. The central axis of the output shaft 661B is approximately consistent with the central axis of the housing 661A. The output shaft 661B is rotatable relative to the housing 661A. The output shaft 661B rotates around its own central axis. The output shaft 661B is rotatable in both forward and reverse directions based on the power supplied to the housing 661A.

[0257] The reducer 662 is located on the upper side relative to the electric motor 661. The reducer 662 includes a reducer body 662A and a flange 662B. The reducer body 662A has a cylindrical shape. The central axis of the reducer body 662A extends approximately in the Z direction. The central axis of the reducer body 662A is approximately consistent with the central axis of the housing 661A of the electric motor 661. The diameter of the reducer body 662A is approximately consistent with the diameter of the through-hole 654A of the support wall portion 654. The reducer body 662A penetrates the through-hole 654A of the support wall portion 654. In addition, a portion of the reducer body 662A is located within the through-hole 654A. The housing 661A of the electric motor 661 is fixed to the lower end surface of the reducer body 662A. The portion of the output shaft 661B of the electric motor 661 that protrudes from the housing 661A is inserted into the interior of the reducer body 662A. The torque of the output shaft 661B of the electric motor 661 is then input to the speed reducer body 662A. The speed reducer body 662A amplifies the torque output by the output shaft 661B of the electric motor 661 at a predetermined ratio and outputs it. The speed reducer body 662A may be, for example, an eccentric oscillating gear type or a planetary gear type. The speed reducer body 662A may be of any type as long as it can amplify and output the torque from the electric motor 661.

[0258] The flange 662B protrudes from the outer peripheral surface of the reducer body 662A. The flange 662B extends over the entire area of the reducer body 662A in the circumferential direction centered on the central axis of the reducer body 662A. That is, the flange 662B is annular. The flange 662B is located on the upper side relative to the upper surface of the support wall portion 654. The lower surface of the flange 662B is opposite to the upper surface of the support wall portion 654. The flange 662B and the support wall portion 654 are fixed to each other by a plurality of bolts 667. In this way, the reducer 662 and the drive device 660 are mounted on the support wall portion 654, which is part of the vehicle body, via the flange 662B.

[0259] The output member 663 is located on the upper side relative to the reducer body 662A. The output member 663 is disc-shaped. The central axis of the output member 663 is roughly consistent with the central axis of the reducer body 662A. The output member 663 is connected to the reducer body 662A. The torque output by the reducer body 662A is input to the output member 663. The output member 663 receives the torque from the reducer body 662A and rotates around its own central axis. That is, when the central axis of the output member 663 is set to the rotation center axis 660V, the output member 663 and the drive device 660 output the torque centered on the rotation center axis 660V.

[0260] The upper surface of the output member 663 faces the lower surface of the swing bracket 665. The output member 663 and the swing bracket 665 are secured to each other by a plurality of bolts 666. Therefore, the swing bracket 665 receives torque from the output member 663 and the drive unit 660, rotating about the rotational axis 660V. As described above, the drive unit 660 is mounted on the support wall 654. In other words, the swing bracket 665 is connected to the support wall 654 via the drive unit 660, allowing it to rotate about the rotational axis 660V. As described above, the electric motor 661, the reducer 662, and the output member 663 are coaxially arranged. This leads to the following conclusion: the output shaft 661B of the electric motor 661 outputs torque centered about the rotational axis 660V. Furthermore, the reducer 662, coaxial with the electric motor 661, transmits the torque output by the electric motor 661 to the output member 663 and the swing bracket 665.

[0261] <Function of the Third Embodiment>

[0262] The following describes the assembly process for the drive unit 660 and swing bracket 665 during the manufacturing process of the excavator 650. As a preliminary step in this assembly process, the operator prepares an integrated structure consisting of the swing bracket 665 and the base wall 534 of the boom 530. Furthermore, the operator prepares the drive unit 660, which integrates the electric motor 661, the speed reducer 662, and the output member 663. In this state, the operator first installs the drive unit 660 on the support wall 654 of the upper body 653. Specifically, the operator inserts the drive unit 660 from above into the through-hole 654A of the support wall 654. When the flange 662B of the speed reducer 662 contacts the upper surface of the support wall 654, the operator secures the flange 662B and the support wall 654 with bolts 667. Then, the operator places the swing bracket 665 from above onto the output member 663 of the drive unit 660. Then, the operator fixes the swing bracket 665 and the output member 663 with the bolts 666. That is, the operator inserts the bolts 666 into the swing bracket 665 from above to integrate the swing bracket 665 and the output member 663.

[0263] <Effects of the Third Embodiment>

[0264] (3-1) In the excavator 650 of this embodiment, when the output shaft 661B of the electric motor 661 rotates, the swing bracket 665 rotates. Simultaneously, the boom 530 swings left and right. Thus, in the excavator 650 of this embodiment, the boom 530 can be swung left and right using the electric motor 661 as the driving source.

[0265] Here, in the excavator 650 of this embodiment, the drive device 660 is directly connected to the swing bracket 665. With this structure of this embodiment, when implementing a swing mechanism for the boom 530 driven by the electric motor 661, no additional mechanism or component is required between the drive device 660 and the swing bracket 665 to transmit the torque of the electric motor 661 to the swing bracket 665. Therefore, with the structure of this embodiment, when implementing a swing mechanism for the boom 530 driven by the electric motor 661, the number of components can be minimized.

[0266] (3-2) In the drive device 660 of this embodiment, the electric motor 661, the speed reducer 662, and the output member 663 are coaxially arranged. In the structure of this embodiment, the overall shape of the drive device 660 is cylindrical. If the drive device 660 is cylindrical, when the drive device 660 is mounted on the support wall portion 654, the drive device 660 can be mounted on the support wall portion 654 simply by inserting the drive device 660 straightly into the through hole 654A. In the structure of this embodiment, the assembly operation of the drive device 660 relative to the support wall portion 654 becomes easy.

[0267] (3-3) In the excavator 650 of the present embodiment, the swing bracket 665 is located on the upper side relative to the drive unit 660. With respect to the structure of the present embodiment, the following comparative example is conceivable. That is, in the comparative example, while maintaining the Z-direction position of the drive unit 660 in the same state as in the above-mentioned embodiment, the swing bracket 665 is arranged on the lower side relative to the drive unit 660. In the case of this comparative example, the following problem occurs in the assembly work of the drive unit 660 and the swing bracket 665 performed by the operator. That is, the operator needs to drill into a narrow space on the lower side relative to the drive unit 660 and the swing bracket 665 and perform the work in an environment with poor visibility. When the work is performed under such conditions, the operability of assembling the drive unit 660 and the swing bracket 665 deteriorates.

[0268] In this regard, when the swing bracket 665 is positioned upward relative to the drive unit 660, as in this embodiment, the operator is not restricted by the workspace when assembling the drive unit 660 and the swing bracket 665, and can easily maintain a clear working field. In other words, the structure of this embodiment provides excellent workability in assembling the drive unit 660 and the swing bracket 665.

[0269] Furthermore, when the swing bracket 665 is positioned upward relative to the drive unit 660, the swing bracket 665 and the output member 663 of the drive unit 660 can be positioned higher and above the ground. In this case, sand and dirt are less likely to accumulate around the swing bracket 665 and the output member 663. If sand and dirt accumulate around the swing bracket 665 and the output member 663, this sand and dirt will create frictional resistance to the rotation of the output member 663 and the swing bracket 665, potentially burdening their movement. To avoid this burden, if sand and dirt accumulate around the output member 663 and the swing bracket 665, maintenance is required to remove the sand and dirt. The structure of this embodiment reduces the need for maintenance to remove sand and dirt from around the output member 663 and the swing bracket 665.

[0270] <Modification of the Third Embodiment>

[0271] The third embodiment can be modified and implemented as follows: The first to third embodiments and the following modified examples can be combined and implemented within a range that does not technically conflict with each other.

[0272] The positional relationship between the swing bracket 665 and the driving device 660 is not limited to the example of the above embodiment. For example, the driving device 660 may be located on the upper side relative to the swing bracket 665.

[0273] The mechanism for fixing the swing bracket 665 and the driving device 660 is not limited to the bolt 666. As long as the swing bracket 665 and the driving device 660 can be fixed, the mechanism is not limited.

[0274] The structure of the swing bracket 665 is not limited to the example in the above embodiment. The swing bracket 665 only needs to be fixed to the boom 530 and capable of receiving torque from the drive device 660 and rotating about the rotation center axis of the drive device 660. For example, the shape of the swing bracket 665 may be modified from the example in the above embodiment.

[0275] The position at which the arm 530 is fixed to the swing bracket 665 is not limited to the example in the above embodiment. The arm 530 may be fixed to any position in the swing bracket 665.

[0276] The structure of the vehicle body for mounting the drive device 660 is not limited to the example of the above embodiment. In order to appropriately mount the drive device 660, the structure of the vehicle body can be appropriately designed.

[0277] The structure of the drive device 660 is not limited to the example of the above embodiment. The drive device 660 only needs to be mounted on the vehicle body, include an electric motor 661, and output torque centered about its central axis of rotation. For example, the outer shape of the electric motor 661 can be modified from a cylindrical shape. For example, the reducer 662 and the output member 663 can be omitted from the drive device 660. In this case, the output shaft 661B of the electric motor 661 can serve as the output member of the drive device 660. Furthermore, the swing bracket 665 can be directly mounted to the output shaft 661B of the electric motor 661. In addition, the drive device 660 can be configured so that the central axis of the output shaft 661B of the electric motor 661 and the central axis of rotation of the torque output by the drive device 660 to the outside are arranged at different positions. If a mechanism that changes the rotation direction of the output shaft 661B of the electric motor 661 is provided in the drive device 660, such a structure is also possible. It is sufficient that the rotation center axis of the torque output by the driving device 660 extends along the vertical direction of the vehicle body as a whole. For example, it may be inclined within a range of about 15 degrees with respect to the Z direction.

[0278] In excavator 650, the slewing bearing 603 is not essential. Specifically, depending on the structure of excavator 650, the upper body 653 may not be able to swivel relative to the lower body 602, and the upper body 653 and the lower body 602 may be integrally formed. In this case, the upper body 653 and the lower body 602 constitute the vehicle body. That is, the vehicle body is not limited to the example in the above embodiment.

[0279] The construction machine to which the boom swing mechanism 650A, which is an electric actuator, is applied is not limited to the excavator 650 .

[0280] In the above embodiment, various mechanisms can be used to fix the two members. Examples of the mechanism to fix the two members include bolt fastening, welding, integral molding, spline connection, and the like.

[0281] In the above embodiment, a portion composed of multiple objects may be integrated into the multiple objects, and conversely, a portion composed of one object may be divided into multiple objects. Regardless of integration or not, it is sufficient as long as the purpose of the present invention can be achieved.

[0282] <Fourth embodiment>

[0283] Below, use Figures 10 to 14 A fourth embodiment of a construction machine and an electric actuator for a construction machine will be described. It should be noted that the drawings may sometimes show structural members in an enlarged manner for easier understanding. In addition, the dimensional ratios of structural members may sometimes differ from the actual dimensional ratios or the dimensional ratios in other drawings. Figures 10 to 14 In, with Figures 1 to 9 Parts that perform the same or substantially the same function are marked with Figures 1 to 9 The same reference numerals are used. Figure 10 、 Figure 11 、 Figure 13 and Figure 14 In the following description, for parts that overlap with the first to third embodiments, the description may be appropriately omitted or simplified.

[0284] Overall Structure

[0285] like Figure 10As shown, an excavator 680 serving as a construction machine includes a lower body 602, an upper body 606 serving as a vehicle body, a pair of travel devices 510, and a slewing bearing 603. The structures of the lower body 602, the pair of travel devices 510, and the slewing bearing 603 are identical to those of the second embodiment. Therefore, their description is omitted. The upper body 606 will be described later. Relative to the lower body 602, the upper body 606 is located on the side opposite to the ground. Furthermore, in this embodiment, the definitions of up, down, left, right, front, and back are the same as in the second embodiment.

[0286] The structure of the upper body 606 is basically the same as that of the second embodiment. That is, the upper body 606 has a rectangular parallelepiped accommodating portion 607, a boarding portion 608 located on the upper side relative to the accommodating portion 607, and a support wall portion 609 located on the front side relative to the accommodating portion 607. The support wall portion 609 has a through hole 609A that passes through in approximately the Z direction. The center axis of the through hole 609A constitutes the rotation center axis 610V of the boom 530. In addition, unlike the second embodiment, in the upper body 606, an opening portion 607H that connects the inside and outside of the accommodating portion 607 is provided in the lower part of the front wall of the accommodating portion 607. In addition, in order to take into account the provision of this opening portion 607H, the support wall portion 609 protruding from the front wall of the accommodating portion 607 is provided only on the upper side relative to the opening portion 607H. As a result, the dimension of the support wall portion 609 in the Z direction is smaller than the dimension of the connecting wall 613 of the swing bracket 610 described later in the Z direction. Figure 11 、 Figure 13 and Figure 14 In FIG, for convenience, the support wall portion 609 is indicated by a double-dashed line. Figure 11 、 Figure 13 and Figure 14 , a portion of the accommodation portion 607 is cut away for illustration.

[0287] like Figure 10 As shown, excavator 680 as an excavation machine includes a boom 530, an arm 540, and a bucket 550. Boom 530, arm 540, and bucket 550 are located forward relative to upper body 606. The structures of boom 530, arm 540, and bucket 550 are the same as those of the second embodiment. Therefore, their description is omitted.

[0288] <Boom swing mechanism>

[0289] like Figure 10 As shown, the excavator 680 includes a boom swing mechanism 680A. The boom swing mechanism 680A is a mechanism for swinging the boom 530 left and right relative to the upper body 606. The boom swing mechanism 680A constitutes an electric actuator.

[0290] The boom swing mechanism 680A includes a swing bracket 610 and a pin 620. The structures of the swing bracket 610 and the pin 620 are the same as those of the second embodiment. Figure 10 As shown, the swing bracket 610 has an upper wall 611, a lower wall 612 and a connecting wall 613. Figure 11 As shown in FIG. 6 , the upper wall 611 and the lower wall 612 are pentagonal when viewed from above. As in the second embodiment, the upper wall 611 is a structure formed by connecting the first part of the quadrilateral and the second part of the triangle. The same is true for the lower wall 612. Figure 11 、 Figure 13 and Figure 14 In the figure, a portion of the upper wall 611 is cut away to show the above. Figure 10 As shown, the connecting wall 613 connects the front portion of the upper wall 611 and the lower wall 612. The base wall 534 of the boom 530 is fixed to the surface of the connecting wall 613 opposite the surface facing the support wall portion 609. Further description of the upper wall 611, the lower wall 612, and the connecting wall 613 is omitted.

[0291] The swing bracket 610 is connected to the support wall portion 609 of the upper body 606 via the pin 620. That is, the pin 620 passes through the through hole 609A of the support wall portion 609 and passes through the upper wall 611 and the lower wall 612. Figure 10 , the gap between the through-hole 609A and the pin 620 is shown in an exaggerated manner. Similar to the second embodiment, the pin 620 is in a state where it can rotate relative to the through-hole 609A. The pin 620 is supported by the through-hole 609A so as to rotate around the central axis of the through-hole 609A, i.e., the rotation center axis 610V. On the other hand, the pin 620 is fixed to the upper wall 611 and the lower wall 612. Therefore, when the pin 620 rotates around the rotation center axis 610V, the upper wall 611 and the lower wall 612 rotate together with the pin 620. In other words, the swing bracket 610 can rotate around the rotation center axis 610V.

[0292] like Figure 11 As shown, the boom swing mechanism 680A has an extension member 685. The extension member 685 is located at the rear portion of the swing bracket 610. The extension member 685 has an extension wall 685A and a swing connecting shaft 685B. Figure 10 In the figure, the extension member 685 is omitted.

[0293] like Figure 11 As shown, the extension wall 685A is, for example, a quadrilateral plate. The extension wall 685A is fixed to the lower wall 612 of the swing bracket 610. Specifically, the extension wall 685A is fixed to the edge of the lower wall 612 corresponding to one side of the triangle. In this embodiment, the extension wall 685A is located on the right side relative to the rotation center axis 610V. Figure 12As shown, the swing connecting shaft 685B protrudes upward from the upper surface of the extension wall 685A. The swing connecting shaft 685B is cylindrical. The central axis of the swing connecting shaft 685B extends generally in the Z direction. In other words, the central axis of the swing connecting shaft 685B is generally parallel to the rotation center axis 610V.

[0294] like Figure 11 As shown, the boom swing mechanism 680A has a vehicle body connecting shaft 687. The vehicle body connecting shaft 687 is located in the accommodation portion 607 in the upper body 606. In the X direction, the vehicle body connecting shaft 687 is located on the front side relative to the bearing axis 603V. As already described in the second embodiment, the bearing axis 603V is located approximately in the center of the accommodation portion 607 in both the X direction and the Y direction. In the Y direction, the vehicle body connecting shaft 687 is located on the right side relative to the right end of the outer ring 605 of the rotary bearing 603. In addition, in the Y direction, the vehicle body connecting shaft 687 is located on the right side relative to the swing connecting shaft 685B. As Figure 12 As shown, the vehicle body connecting shaft 687 protrudes upward from the lower wall of the accommodating portion 607. The vehicle body connecting shaft 687 is cylindrical. The central axis of the vehicle body connecting shaft 687 extends generally in the Z direction. In other words, the central axis of the vehicle body connecting shaft 687 is generally parallel to the rotation center axis 610V.

[0295] Power Unit

[0296] like Figure 10 and Figure 11 As shown, the boom swing mechanism 680A has a power unit 700. Figure 10 In the figure, for convenience, the power unit 700 is indicated by a two-dot chain line. Most of the power unit 700 is located in the accommodation portion 607. A portion of the power unit 700 protrudes from the accommodation portion 607 toward the front direction.

[0297] like Figure 12 As shown, the power unit 700 includes a first component 701. The first component 701 is cylindrical. Hereinafter, the central axis of the first component 701 is referred to as a reference axis 701C. The reference axis 701C extends in a direction substantially perpendicular to the Z direction. In addition, hereinafter, when there is no need to distinguish between two directions along the reference axis 701C, they are collectively referred to as reference axis directions 701L. Furthermore, a specific direction in the reference axis directions 701L is referred to as a positive direction, and the opposite direction is referred to as a negative direction.

[0298] The power unit 700 includes a first connecting wall 705. The first connecting wall 705 is located on the lower side relative to the first member 701. The first connecting wall 705 is located near the end of the first member 701 on the negative side. The first connecting wall 705 is fixed to the first member 701. The first connecting wall 705 is cylindrical. The central axis of the first connecting wall 705 extends approximately in the Z direction. The inner diameter of the first connecting wall 705 is approximately the same as the diameter of the vehicle body connecting shaft 687. The first connecting wall 705 accommodates the vehicle body connecting shaft 687. The first connecting wall 705 is rotatable relative to the vehicle body connecting shaft 687. That is, the first connecting wall 705 and the first member 701 are connected to the accommodating portion 607 in a state where they can rotate about the central axis of the vehicle body connecting shaft 687.

[0299] The power unit 700 has a second member 702. The second member 702 is inserted into the interior of the first member 701 from the end on the positive direction side of the first member 701. The end of the second member 702 on the positive direction side protrudes from the first member 701 to the positive direction side. The second member 702 extends along the reference axis 701C. The second member 702 is cylindrical. The center axis of the second member 702 is roughly consistent with the reference axis 701C. The size of the second member 702 in the reference axis direction 701L is larger than the size of the first member 701 in the reference axis direction 701L. The outer diameter of the second member 702 is slightly smaller than the inner diameter of the first member 701. In addition, the outer peripheral surface of the second member 702 is in a state of being able to slide relative to the inner peripheral surface of the first member 701. An internal thread is cut on the inner peripheral surface of the second member 702. The internal thread is formed in substantially the entire area of the reference axis direction 701L in the second member 702. Figure 12 The second member 702 is capable of reciprocating relative to the first member 701 in a reference axis direction 701L by a force from a drive mechanism 710 described later.

[0300] The power unit 700 has a second connecting wall 707. The second connecting wall 707 is located at the end on the positive direction side of the second member 702. For example, the second connecting wall 707 is in the shape of a rectangular parallelepiped. The second connecting wall 707 blocks the opening at the end on the positive direction side of the second member 702. The second connecting wall 707 is fixed to the end on the positive direction side of the second member 702. The second connecting wall 707 has a accommodating recess 707A. The accommodating recess 707A is open to the downward direction side. The outer shape of the accommodating recess 707A is cylindrical. The diameter of the accommodating recess 707A is substantially the same as the diameter of the swing connecting shaft 685B. The accommodating recess 707A accommodates the swing connecting shaft 685B. The second connecting wall 707 is capable of relative rotation relative to the swing connecting shaft 685B. That is, the second connection wall 707 and the second member 702 are connected to the extension member 685 and the swing bracket 610 in a state rotatable around the central axis of the swing connection shaft 685B.

[0301] In addition, if Figure 11 As shown, to balance the positions of the vehicle body connecting shaft 687 and the swing connecting shaft 685B, the first member 701 and the second member 702 connected to the vehicle body connecting shaft 687 and the swing connecting shaft 685B are positioned to the right of the center of the housing portion 607 in the Y direction. Furthermore, the reference axis 701C is inclined with respect to the X direction such that it is positioned to the right as it moves toward the rear.

[0302] <Drive Mechanism>

[0303] like Figure 12 As shown, the power unit 700 has an electric drive mechanism 710. The drive mechanism 710 has a housing 711. The housing 711 has a first portion 711A and a second portion 711B. The first portion 711A is located on the upper side relative to the first member 701. In the reference axis direction 701L, the first portion 711A is located on the negative side relative to the center of the first member 701. The first portion 711A is cylindrical. The central axis of the first portion 711A is approximately parallel to the reference axis 701C. The positive end of the first portion 711A is blocked. The second portion 711B is located on the negative side relative to the first portion 711A. The second portion 711B is rectangular. The second portion 711B is hollow. In the Z direction, the second portion 711B is within the range spanning the first portion 711A and the first member 701. The first side wall 711P, one of the plurality of side walls in the second portion 711B, is connected to the negative end of the first portion 711A and the negative end of the first member 701. The interior of the second portion 711B communicates with the interior of the first portion 711A. Furthermore, the interior of the second portion 711B communicates with the interior of the first member 701.

[0304] The drive mechanism 710 includes an electric motor 712. The electric motor 712 is the driving source of the drive mechanism 710, driving the second member 702 to reciprocate relative to the first member 701. The electric motor 712 is located inside the first portion 711A of the housing 711. The electric motor 712 operates based on power supplied by a battery (not shown). The electric motor 712 includes a housing 712A and an output shaft 712B. The housing 712A is fixed to the inner wall of the first portion 711A. The output shaft 712B protrudes from the housing 712A. The output shaft 712B is cylindrical in shape. The central axis of the output shaft 712B extends approximately parallel to the reference axis 701C. The output shaft 712B is rotatable relative to the housing 712A. The output shaft 712B rotates about its own central axis. In other words, the central axis of the output shaft 712B is the rotational axis of the electric motor 712. The output shaft 712B can rotate in both forward and reverse directions according to the power supplied to the housing 712A.

[0305] The drive mechanism 710 includes a speed reducer 713. In the reference axis direction 701L, the speed reducer 713 is adjacent to the electric motor 712. Relative to the electric motor 712, the speed reducer 713 is located on the negative side. Similar to the electric motor 712, the speed reducer 713 is located inside the first portion 711A of the housing 711. The speed reducer 713 is fixed to the inner wall of the first portion 711A. The speed reducer 713 is connected to the output shaft 712B of the electric motor 712. Furthermore, the torque of the output shaft 712B of the electric motor 712 is input to the speed reducer 713. The speed reducer 713 amplifies and outputs the torque of the output shaft 712B of the electric motor 712 at a predetermined ratio. The speed reducer 713 is, for example, an eccentric oscillating gear type or a planetary gear type. The speed reducer 713 may be any type of speed reducer as long as it is a structure capable of amplifying and outputting the torque from the electric motor 712.

[0306] The drive mechanism 710 includes an output member 714. The output member 714 protrudes from the reducer 713 toward the negative direction. The output member 714 is located inside the second portion 711B of the housing 711. The output member 714 is cylindrical. The central axis of the output member 714 is substantially aligned with the central axis of the output shaft 712B of the electric motor 712. In other words, the central axis of the output member 714 is substantially parallel to the reference axis 701C. The output member 714 is connected to the reducer 713. The output member 714 receives torque from the reducer 713 and rotates about its own central axis.

[0307] The drive mechanism 710 includes a screw shaft 718. The screw shaft 718 is inserted into the interior of the second member 702 from the end on the negative side of the second member 702. A portion of the screw shaft 718 that faces the negative direction protrudes from the second member 702 toward the negative side. The portion of the screw shaft 718 that protrudes from the second member 702 is located inside the second portion 711B of the housing 711. The screw shaft 718 is cylindrical. The diameter of the screw shaft 718 is smaller than the inner diameter of the second member 702. The center axis of the screw shaft 718 is approximately aligned with the reference axis 701C. An external thread is cut into the outer circumferential surface of the screw shaft 718. The external thread is formed on substantially the entire area of the screw shaft 718 in the reference axis direction 701L. In addition, in the reference axis direction 701L, the negative end of the screw shaft 718 is located at approximately the same position as the negative end of the output member 714.

[0308] The driving mechanism 710 has a plurality of balls 719. Figure 12, six of the plurality of balls 719 are shown as representatives. The number of balls 719 is not limited to six. The plurality of balls 719 are located between the inner circumferential surface of the second component 702 and the outer circumferential surface of the screw shaft 718. The plurality of balls 719 are retained between the inner circumferential surface of the second component 702 and the outer circumferential surface of the screw shaft 718. The plurality of balls 719 guide the screw shaft 718 to rotate relative to the second component 702. Guided by the balls 719, the screw shaft 718 rotates about its own center axis and the reference axis 701C.

[0309] The drive mechanism 710 includes a transmission mechanism 715. The transmission mechanism 715 is located inside the second portion 711B of the housing 711. The transmission mechanism 715 includes, for example, a cylindrical first pulley, a cylindrical second pulley, and a belt. An output member 714 is mounted on the first pulley. The first pulley rotates integrally with the output member 714. A screw shaft 718 is mounted on the second pulley. The second pulley rotates integrally with the screw shaft 718. The belt is wound around the first and second pulleys. The belt transmits the rotation of the first pulley to the second pulley. The belt causes the first and second pulleys to operate in conjunction with each other. With this structure, the transmission mechanism 715 transmits the rotation of the output shaft 712B of the electric motor 712 and the output member 714 to the screw shaft 718. Furthermore, the electric motor 712 rotates the screw shaft 718. That is, the screw shaft 718 rotates about the reference axis 701C as the output shaft 712B of the electric motor 712 rotates. Furthermore, the transmission mechanism 715 may be any type of transmission mechanism as long as it enables the output member 714 and the lead screw shaft 718 to operate in conjunction with each other. For example, the transmission mechanism 715 may utilize a combination of a sprocket and a chain instead of a pulley and a belt. For example, the transmission mechanism 715 may also utilize a gear mechanism that enables the output member 714 and the lead screw shaft 718 to operate in conjunction with each other through the meshing of gears.

[0310] <Function of the Fourth Embodiment>

[0311] In the power unit 700, when the output shaft 712B of the electric motor 712 rotates, the rotation of the output shaft 712B is transmitted to the screw shaft 718. The screw shaft 718 rotates in either the forward or reverse direction according to the rotation direction of the output shaft 712B of the electric motor 712. The rotation of the screw shaft 718 is transmitted to the second component 702 via the ball 719. Furthermore, if the screw shaft 718 rotates, the second component 702 moves relative to the screw shaft 718 and the first component 701 in the reference axis direction 701L. That is, the second component 702 receives a force from the screw shaft 718 via the ball 719, thereby generating movement. As Figure 12As indicated by arrow 702V, the second member 702 moves in the positive or negative direction relative to the first member 701 in accordance with the rotation direction of the screw shaft 718. As the second member 702 moves, the amount of protrusion of the second member 702 relative to the first member 701 increases or decreases. In other words, the power unit 700 expands and contracts in the reference axis direction 701L.

[0312] As described above, the telescopic movement of the power unit 700 drives the swing bracket 610 and the boom 530 to swing left and right. Figure 11 As shown, the position of the extension member 685 when the swing bracket 610 and the boom 530 are facing forward relative to the upper body 606 is used as the basic position. Furthermore, the full length of the power unit 700 at this time is used as the first value. Specifically, the full length of the power unit 700 is the length of the power unit 700 along the reference axis 701C.

[0313] First, the swing of the boom 530 to the left will be described. Currently, the extension member 685 is in the basic position. In this state, it is assumed that the second member 702 moves to the positive direction relative to the first member 701. As a result, the total length of the power unit 700 becomes longer than the first value. Figure 13 As shown, the extension member 685 connected to the power unit 700 is relative to Figure 11 The basic position shown has moved forward. Specifically, the extension member 685 is spaced away from the front wall of the housing portion 607 of the upper body 606. Furthermore, the swing bracket 610 connected to the extension member 685 rotates leftward about the rotation axis 610V. Simultaneously, the boom 530 rotates leftward about the rotation axis 610V.

[0314] Next, the swing of the boom 530 to the right will be described. Currently, the extension member 685 is in the basic position. In this state, it is assumed that the second member 702 moves to the negative direction relative to the first member 701. As a result, the power unit 700 becomes shorter than the first value. Figure 14 As shown, the extension member 685 is relative to Figure 11 The basic position shown is moved rearward. Specifically, the extension member 685 approaches the front wall of the housing portion 607 of the upper body 606. Simultaneously, the swing bracket 610 connected to the extension member 685 rotates clockwise about the rotation axis 610V. Furthermore, the boom 530 rotates clockwise about the rotation axis 610V.

[0315] As described above, the boom 530 swings as the power unit 700 is extended or retracted. Although detailed illustrations are omitted, when the boom 530 swings, the reference axis 701C rotates left and right with the vehicle body connection shaft 687 as the center. By rotating the reference axis 701C in this way, the power unit 700 is allowed to freely extend or retract. That is, in this embodiment, the power unit 700 is rotatably connected to the vehicle body connection shaft 687 and the swing connection shaft 685B, thereby allowing the power unit 700 to be extended or retracted to a large extent. Furthermore, by being able to ensure the power unit 700 to be extended or retracted to a large extent, a wide range of rotation of the swing bracket 610 can be achieved.

[0316] <Effects of the Fourth Embodiment>

[0317] (4-1) As described in the operation of the above embodiment, in the excavator 680 of this embodiment, the boom 530 can be swung left and right using the electric motor 712 as a driving source.

[0318] (4-2) In the excavator 680 of this embodiment, the rotational motion of the electric motor 712, which serves as a driving source, is converted into linear motion of the second member 702, thereby causing the second member 702 to reciprocate relative to the first member 701. In this embodiment, a so-called ball screw mechanism is used as the mechanism for performing this motion conversion. A ball screw mechanism can smoothly convert rotational motion into linear motion.

[0319] (4-3) As described in the first embodiment, a load can be input from the outside to the boom 530 due to the collision between the bucket 550 and the excavation object. This load is referred to as a collision load. In the case of the excavator 680 of this embodiment, the collision load can be transmitted to the screw shaft 718 via the swing bracket 610, the extension member 685, and the second member 702. Here, the collision load acting on the screw shaft 718 mainly has a component in the reference axis direction 701L, which is the extension direction of the screw shaft 718. On the other hand, this collision load is unlikely to act as a force that causes the various components to move in a direction intersecting the reference axis direction 701L. In other words, the collision load acting on the screw shaft 718 is unlikely to be transmitted as a force from the screw shaft 718 toward the Z direction. Therefore, the collision load acting on the screw shaft 718 is unlikely to be transmitted to the transmission mechanism 715 and the output member 714. Therefore, in the structure of this embodiment, it is possible to prevent the collision load acting on the screw shaft 718 from affecting the speed reducer 713 and the electric motor 712. As described in the second embodiment, this eliminates the need to provide a structure for receiving the collision load in the speed reducer 617 and the electric motor 712. Therefore, for example, an increase in the size of the speed reducer 713 can be suppressed.

[0320] <Modification of Fourth Embodiment>

[0321] The fourth embodiment can be modified and implemented as follows: The first to fourth embodiments and the following modified examples can be combined and implemented within a range that does not technically conflict with each other.

[0322] The structure of the power transmission path from the electric motor 712 to the screw shaft 718 is not limited to the example of the above embodiment. For example, in this power transmission path, the reducer 713 and the output member 714 can also be omitted from between the electric motor 712 and the screw shaft 718. In addition, the output shaft 712B of the electric motor 712 and the screw shaft 718 can be connected by a transmission mechanism 715. In addition, in this power transmission path, the transmission mechanism 715 can also be omitted. In addition, the screw shaft 718 and the electric motor 712 can also be coaxially arranged. In other words, the rotation center axis of the electric motor 712 and the reference axis 701C do not need to be arranged in parallel at different positions. The power transmission path only needs to be configured so that the rotation of the electric motor 712 can be transmitted to the screw shaft 718.

[0323] The connection destination of the first member 701 and the connection destination of the second member 702 may be interchanged according to the above embodiment. That is, the first member 701 may be connected to the swing connection shaft 685B, and the second member 702 may be connected to the vehicle body connection shaft 687.

[0324] The arrangement of the vehicle body connecting shaft 687 is not limited to the example of the above embodiment. The vehicle body connecting shaft 687 may be installed somewhere on the vehicle body in consideration of the rotation range of the swing bracket 610 and the boom 530.

[0325] The placement of the swing coupling shaft 685B is not limited to the example in the above embodiment. For example, the swing coupling shaft 685B may be provided on the swing bracket 610 itself. The swing coupling shaft 685B may be provided so as to operate integrally with the swing bracket 610, taking into account the rotational range of the swing bracket 610 and the boom 530, which is determined by its positional relationship with the vehicle body coupling shaft 687.

[0326] If the arrangement of the swing coupling shaft 685B and the vehicle body coupling shaft 687 is changed from that of the above-described embodiment, the arrangement of the power unit 700 will also be changed accordingly. In this case, the excavator 680 can be configured so as not to hinder the extension and contraction of the power unit 700 and to enable the extension and contraction to be transmitted to the swing bracket 610.

[0327] The structure and arrangement of the first connecting wall 705 are not limited to the examples in the above-described embodiment. For example, the first connecting wall 705 may be located near the center of the first member 701 in the reference axis direction 701L. The first connecting wall 705 only needs to be able to accommodate the vehicle body connecting shaft 687 and be able to rotate relative to the vehicle body connecting shaft 687. Similar to the first connecting wall 705, the structure and arrangement of the second connecting wall 707 are not limited to the examples in the above-described embodiment. The second connecting wall 707 only needs to be able to accommodate the swing connecting shaft 685B and be able to rotate relative to the swing connecting shaft 685B.

[0328] The method of connecting the first member 701 and the second member 7021 so as to be rotatable relative to the object is not limited to the example of the above embodiment. For example, the first member 701 and the second member 702 can be connected to the object without using an integral wall portion such as the first connecting wall 705 and the second connecting wall 707. The first member 701 can be connected to one of the vehicle body and the swing bracket 610 in a state where it can rotate around a central axis parallel to the rotation center axis 610V. The second member 702 can be connected to the other of the vehicle body and the swing bracket 610 in a state where it can rotate around a central axis parallel to the rotation center axis 610V.

[0329] Similar to the modified example of the second embodiment, the structure, configuration and connection method of the swing bracket 610 to the vehicle body are not limited to the example of the above embodiment. The swing bracket 610 only needs to be fixed to the boom 530 and connected to the vehicle body in a manner that allows it to rotate around the rotation center axis 610V. In addition, similar to the modified example of the second embodiment, the structure of the vehicle body for supporting the swing bracket 610 is not limited to the example of the above embodiment. The rotation center axis 610V can also be offset from the center of the accommodating portion 607 in the Y direction. The rotation center axis 610V only needs to extend along the upper and lower sides of the vehicle body as a whole. For example, it may be inclined relative to the Z direction within a range of about 15 degrees. As for the structure, configuration and connection method of the swing bracket 610 to the vehicle body, for example, the sixth embodiment described later may also be adopted. Figure 24 Same structure.

[0330] The fixing position of the arm 530 and the swing bracket 610 is not limited to the example of the above embodiment. The arm 530 can be fixed to any position of the swing bracket 610.

[0331] In excavator 680, slewing bearing 603 is not essential. Specifically, depending on the structure of excavator 680, upper body 606 may not be able to swivel relative to lower body 602, and upper body 606 and lower body 602 may be integrally formed. In this case, upper body 606 and lower body 602 constitute the vehicle body. That is, the vehicle body is not limited to the example in the above embodiment.

[0332] The construction machine to which the boom swing mechanism 680A, which is an electric actuator, is applied is not limited to the excavator 680 .

[0333] In the above embodiment, various mechanisms can be used to fix the two members. Examples of the mechanism to fix the two members include bolt fastening, welding, integral molding, spline connection, and the like.

[0334] In the above embodiment, a portion composed of multiple objects may be integrated into the multiple objects, and conversely, a portion composed of one object may be divided into multiple objects. Regardless of integration or not, it is sufficient as long as the purpose of the present invention can be achieved.

[0335] The structure of the power unit 700 is not limited to the example in the above embodiment. The power unit 700 can be configured so that its entire length expands and contracts with the relative movement of the second member 702 relative to the first member 701. Furthermore, the excavator 680 can be configured so that the expansion and contraction of the power unit 700 can be transmitted to the rotation of the swing bracket 610. For example, the first member 701 can be cylindrical in shape as a whole and is not limited to a perfect cylinder. The second member 702 can be configured to reciprocate within the first member 701. As long as the first member 701 can be rotatably connected to either the vehicle body or the swing bracket 610, the structure and arrangement of the first connecting wall 705 can be modified from the example in the above embodiment. The structure and arrangement of the second connecting wall 707 are similar. The drive mechanism 710 is not limited to one utilizing a ball screw. The drive mechanism 710 can be electrically driven and capable of outputting a force that causes the second member 702 to reciprocate along the reference axis direction 701L.

[0336] For example, instead of the power unit 700 of the above embodiment, it is also possible to use Figure 15 The power unit 730 shown. In addition, Figure 15 In, with Figures 10 to 14 Parts that perform the same or substantially the same function are marked with Figures 10 to 14 Same reference numerals.

[0337] The power unit 730 includes a first component 731. The first component 731 includes a peripheral wall 731A, a first end wall 731B, a second end wall 731C, a first port hole 731D, and a second port hole 731E. The peripheral wall 731A is cylindrical. Hereinafter, the center axis of the peripheral wall 731A will be referred to as the reference axis 731V. The reference axis 731V extends in a direction substantially perpendicular to the Z direction. Hereinafter, when there is no need to distinguish between the two directions along the reference axis 731V, they will be collectively referred to as the reference axis direction 731L. Furthermore, one of the reference axis directions 731L will be referred to as the positive direction, and the opposite direction will be referred to as the negative direction.

[0338] The first end wall 731B blocks the positive end of the peripheral wall 731A. The second end wall 731C blocks the negative end of the peripheral wall 731A. The peripheral wall 731A, the first end wall 731B, and the second end wall 731C define a fluid chamber 731P for supplying and discharging hydraulic oil. The first port hole 731D is located near the positive end of the peripheral wall 731A. The first port hole 731D penetrates the peripheral wall 731A in a radial direction centered on the reference axis 731V. The second port hole 731E is located near the negative end of the peripheral wall 731A. The second port hole 731E penetrates the peripheral wall 731A in the aforementioned radial direction.

[0339] The power unit 730 has a first connecting wall 705. The first connecting wall 705 is located on the lower side relative to the peripheral wall 731A of the first member 731. The first connecting wall 705 is located near the negative end of the peripheral wall 731A. The first connecting wall 705 is fixed to the peripheral wall 731A. The structure of the first connecting wall 705 is the same as that of the first connecting wall 705. Figure 12 . Specifically, the first connecting wall 705 is cylindrical. The first connecting wall 705 accommodates the vehicle body connecting shaft 687. The first connecting wall 705 is rotatable relative to the vehicle body connecting shaft 687. Specifically, the first connecting wall 705 and the first member 731 are connected to the accommodating portion 607 so as to be rotatable about the central axis of the vehicle body connecting shaft 687.

[0340] The power unit 730 includes a second component 732. The second component 732 includes a piston 732A and a rod 732B. The piston 732A is located in the fluid chamber 731P. The piston 732A is, for example, in the shape of a circular plate. The central axis of the piston 732A is approximately aligned with the reference axis 731V. The diameter of the piston 732A is approximately aligned with the inner diameter of the peripheral wall 731A of the first component 731. The piston 732A divides the fluid chamber 731P into two parts along the reference axis direction 731L. Hereinafter, the portion of the two fluid chambers 731P located on the positive side will be referred to as the first fluid chamber 731P1, and the portion located on the negative side will be referred to as the second fluid chamber 731P2. The rod 732B is inserted into the interior of the first component 731 from the positive end of the first component 731. That is, the rod 732B penetrates the first end wall 731B and is inserted into the interior of the peripheral wall 731A. The rod 732B is cylindrical. The central axis of rod 732B is substantially aligned with reference axis 731V. The negative end of rod 732B is fixed to piston 732A. That is, when viewed from piston 732A, rod 732B extends from piston 732A toward the positive end. The positive end of rod 732B protrudes from first member 731. The rod 732B and piston 732A as a whole are capable of reciprocating relative to first member 731 along reference axis direction 731L by a force from a drive mechanism 740, described later.

[0341] The power unit 730 has a second connecting wall 707. The second connecting wall 707 is located near the end of the rod 732B on the positive side of the second member 732. The second connecting wall 707 is located on the lower side relative to the rod 732B. The second connecting wall 707 is fixed to the rod 732B. The structure of the second connecting wall 707 is the same as that of the rod 732B. Figure 12 The structure is identical to that described in [ 1 ]. Specifically, the second connecting wall 707 includes a downwardly open accommodating recess 707A. Accommodating recess 707A accommodates the swing connecting shaft 685B. The second connecting wall 707 is rotatable relative to the swing connecting shaft 685B. Specifically, the second connecting wall 707 and the second member 732 are connected to the extension member 685 in a state where they are rotatable about the central axis of the swing connecting shaft 685B.

[0342] The power unit 730 includes an electric drive mechanism 740. The drive mechanism 740 includes a housing 741, a tank 742, an electric motor 743, a pump 744, and a switching valve 745. Furthermore, the drive mechanism 740 includes a first basic flow path 746A, a second basic flow path 746B, a first extended flow path 747A, and a second extended flow path 747B as fluid passages. The drive mechanism 740 constitutes a fluid circuit.

[0343] The housing 741 is located on the upper side relative to the first member 731. The housing 741 is fixed to the first member 731. The housing 741 accommodates the components of the driving mechanism 740.

[0344] Tank 742 stores hydraulic oil. A first basic flow path 746A connects tank 742 and switching valve 745. A second basic flow path 746B connects tank 742 and switching valve 745. A first extension flow path 747A connects switching valve 745 and first port 731D. A second extension flow path 747B connects switching valve 745 and second port 731E. Switching valve 745 switches the connection destination of first basic flow path 746A to either the first extension flow path 747A or the second extension flow path 747B. Switching valve 745 switches the connection destination of second basic flow path 746B to either the first extension flow path 747A or the second extension flow path 747B. Specifically, switching valve 745 switches between a first mode and a second mode. In the first mode, switching valve 745 connects first basic flow path 746A to first extension flow path 747A, and connects second basic flow path 746B to second extension flow path 747B. In the second mode, the switching valve 745 connects the first base flow path 746A to the second extended flow path 747B, and further connects the second base flow path 746B to the first extended flow path 747A. The pump 744 is located midway along the first base flow path 746A. The pump 744 is driven by the electric motor 743. The pump 744 pumps the hydraulic oil in the tank 742 toward the switching valve 745. Furthermore, the electric motor 743 is supplied with electricity from a battery (not shown). The power unit 730 is configured as described above.

[0345] The operation of the power unit 730 will be described. In the power unit 730, Figure 15As shown by arrow 730V, the second member 732 reciprocates along the reference axis direction 731L in accordance with the operation of the drive mechanism 740. In this reciprocating motion, the movement of the second member 732 toward the negative side will be described first. Currently, the piston 732A is located near the center of the peripheral wall 731A of the first member 731 in the reference axis direction 731L. Furthermore, it is assumed that both the first fluid chamber 731P1 and the second fluid chamber 731P2 are filled with hydraulic oil. This state is referred to as the basic state. Assume that in the basic state, the switching valve 745 is set to the first mode and the pump 744 is driven. The hydraulic oil in the tank 742 is then supplied to the first fluid chamber 731P1 via the first basic flow path 746A and the first extended flow path 747A. That is, the first basic flow path 746A and the first extended flow path 747A supply hydraulic oil to the first fluid chamber 731P1 in accordance with the operation of the pump 744. When hydraulic oil is supplied to the first fluid chamber 731P1, hydraulic pressure is applied to the piston 732A in the negative direction. Consequently, the piston 732A moves in the negative direction. Furthermore, the hydraulic oil in the second fluid chamber 731P2 is discharged to the tank 742 via the second extended flow path 747B and the second basic flow path 746B. That is, the second extended flow path 747B and the second basic flow path 746B discharge the hydraulic oil from the second fluid chamber 731P2 in response to the drive of the pump 744. Furthermore, when the piston 732A moves in the negative direction, the piston 732A and the rod 732B as a whole move in the negative direction relative to the first member 731. Consequently, the total length of the power unit 730 in the reference axis direction 731L becomes shorter than its total length in the basic state.

[0346] Next, the movement of the second member 732 toward the positive direction will be described. Assume that, in the above-described basic state, the switching valve 745 is set to the second mode and the pump 744 is driven. The hydraulic oil within the tank 742 is then supplied to the second fluid chamber 731P2 via the first basic flow path 746A and the second extended flow path 747B. That is, the first basic flow path 746A and the second extended flow path 747B supply hydraulic oil to the second fluid chamber 731P2 in response to the driving of the pump 744. When hydraulic oil is supplied to the second fluid chamber 731P2, hydraulic pressure in the positive direction is applied to the piston 732A. As a result, the piston 732A moves toward the positive direction. Furthermore, the hydraulic oil in the first fluid chamber 731P1 is discharged into the tank 742 via the first extended flow path 747A and the second basic flow path 746B. That is, the first extended flow path 747A and the second basic flow path 746B discharge the hydraulic oil from the first fluid chamber 731P1 in response to the driving of the pump 744. When piston 732A moves in the positive direction, piston 732A and rod 732B as a whole move in the positive direction relative to first member 731. Consequently, the total length of power unit 730 in reference axis direction 731L becomes longer than that in the basic state.

[0347] As described above, the second member 732 receives the pressure of the hydraulic oil from the driving mechanism 740 and moves. In addition, the power unit 730 expands and contracts accordingly. Figures 11 to 14 As described in , the extension and retraction of the power unit 730 drives the swing bracket 610 and the boom 530 to swing left and right.

[0348] When the power unit 730 is used in the excavator 680, the following advantages are achieved. As described above in (4-3), a load can be input from the outside into the boom 530 due to the collision between the bucket 550 and the excavation object. This load is referred to as the collision load. When the power unit 730 is used, the collision load can be transmitted to the second member 732 via the swing bracket 610 and the extension member 685. Furthermore, the collision load can act on the second member 732, causing it to move along the reference axis direction 731L. Here, the piston 732A of the second member 732 is located in the fluid chamber 731P. Therefore, when the second member 732 attempts to move due to the collision load, resistance from the hydraulic fluid acts on the piston 732A located in the fluid chamber 731P. Furthermore, the movement of the piston 732A is suppressed by the hydraulic fluid. Consequently, the movement of the piston 732A and the second member 732 is limited to a very small amount. In other words, when power unit 730 is used, the hydraulic pressure in fluid chamber 731P can be used to attenuate the collision load input to second member 732. Therefore, when power unit 730 is used, for example, it is unnecessary to provide a structure for bearing the collision load in drive mechanism 740. This can, for example, prevent the drive mechanism 740 from becoming larger in size.

[0349] In addition, the structure of the power unit 730 is not limited to Figure 15 The power unit 730 only needs to be configured to move the second member 732 relative to the first member 731 according to the pressure of the fluid. Figure 15 For example, the structure of the flow path from the tank 742 to the fluid chamber 731P is changed. The flow path only needs to be configured so as to be able to supply or discharge the working oil relative to the first fluid chamber 731P1 and the second fluid chamber 731P2 according to the action of the pump 744 driven by the electric motor 743. The fluid supplied or discharged relative to the first fluid chamber 731P1 and the second fluid chamber 731P2 is not limited to the working oil. The fluid can be, for example, air. The peripheral wall 731A of the first component 731 is not limited to a cylindrical shape. The peripheral wall 731A can also be a square cylindrical shape. The peripheral wall 731A only needs to be cylindrical as a whole. The shape of the piston 732A can be appropriately changed to adapt to the shape of the peripheral wall 731A. The piston 732A only needs to be able to divide the fluid chamber 731P into two along the reference axis direction 731L. The shape of the rod 732B only needs to be cylindrical and is not limited to a cylindrical shape.

[0350] In the excavator 680, it is also possible to use Figures 16 to 18 The power unit 750 shown. In addition, Figures 16 to 18 In, with Figures 10 to 15 Parts that perform the same or substantially the same function are marked with Figures 10 to 15 Same reference numerals.

[0351] As a premise for explaining the power unit 750, Figure 17 As shown, when the excavator 680 is viewed from above in the direction along the rotation center axis 610V, the imaginary line segment connecting the rotation center axis 610V and the bearing axis 603V is referred to as a first line segment 680X. As described in the second embodiment, in the Y direction, both the rotation center axis 610V and the bearing axis 603V are located approximately in the center of the accommodation portion 607. Therefore, the first line segment 680X extends from approximately the center of the accommodation portion 607 in the Y direction toward the X direction.

[0352] like Figure 16 As shown, the power unit 750 has a first component 751. Figure 17 As shown, the first member 751 is located on the right side relative to the first line segment 680X, that is, relative to the center of the accommodating portion 607 in the Y direction. Figure 16 and Figure 17 As shown, the first member 751 has a quadrilateral cylindrical shape. Hereinafter, the central axis of the first member 751 is referred to as the reference axis 751V. The reference axis 751V extends in a direction substantially perpendicular to the Z direction. Hereinafter, when there is no need to distinguish between the two directions along the reference axis 751V, they are collectively referred to as reference axis directions 751L. Furthermore, a specific direction in the reference axis directions 751L is referred to as the positive direction, and the opposite direction is referred to as the negative direction.

[0353] like Figure 16 As shown in FIG. 7 , the first member 751 has a first wall 751A, a second wall 751B and a third wall 751C. Figure 17 As shown, the first member 751 has a fourth wall 751D. Each wall portion is in the shape of a rectangular plate and is in the shape of a long strip in the reference axis direction 751L. Figure 16 As shown, the main surface of the first wall 751A and the main surface of the second wall 751B face each other up and down. The main surface is the surface with the largest area in the plate-like member. The first wall 751A is located on the upper side relative to the second wall 751B. Figure 16 and Figure 17 As shown, the third wall 751C connects the long sides of the first wall 751A and the second wall 751B to each other. The fourth wall 751D connects the long sides of the first wall 751A and the second wall 751B to each other on the side opposite to the third wall 751C. Figure 17As shown, the fourth wall 751D is located on the central side of the accommodating portion 607 relative to the first wall 751A, the second wall 751B, and the third wall 751C. Figure 18 As shown in FIG. 7 , the fourth wall 751D has a communication port 751P. The communication port 751P is an opening that connects the inside and outside of the first member 751. Figure 17 As shown, the communication port 751P is located near the center of the fourth wall 751D in the reference axis direction 751L.

[0354] like Figure 16 As shown, the power unit 750 has a first connecting wall 705. The first connecting wall 705 is located on the lower side relative to the second wall 751B of the first member 751. The first connecting wall 705 is located near the end of the second wall 751B on the negative side. The first connecting wall 705 is fixed to the second wall 751B. The structure of the first connecting wall 705 is the same as that of the first connecting wall 705. Figure 12 The structure is the same as described in [ 1 ]. That is, the first connecting wall 705 is cylindrical. The first connecting wall 705 accommodates the vehicle body connecting shaft 687. The first connecting wall 705 is rotatable relative to the vehicle body connecting shaft 687. That is, the first connecting wall 705 and the first member 751 are connected to the accommodating portion 607 in a state where they can rotate about the central axis of the vehicle body connecting shaft 687.

[0355] The power unit 750 includes a second member 752. The second member 752 extends across the interior and exterior of the first member 751. The second member 752 includes a main body 752A and a plurality of rack teeth 752B. The main body 752A has a quadrilateral columnar shape. The central axis of the main body 752A is substantially aligned with the reference axis 751V. The main body 752A is inserted into the interior of the first member 751 from the positive end of the first member 751. The portion of the main body 752A near the positive end is exposed from the first member 751. The plurality of rack teeth 752B protrude from the outer surface of the main body 752A facing the fourth wall 751D of the first member 751. The plurality of rack teeth 752B are arranged at equal intervals along the reference axis direction 751L. The plurality of rack teeth 752B are provided over substantially the entire area of the main body 752A in the reference axis direction 751L. The second member 752 is capable of reciprocating relative to the first member 751 in the reference axis direction 751L by the force of a drive mechanism 755 described later.

[0356] The power unit 750 has a second connecting wall 707. The second connecting wall 707 is located near the end of the main body 752A on the positive side of the second member 752. The second connecting wall 707 is located on the lower side relative to the main body 752A. The second connecting wall 707 is fixed to the main body 752A. The structure of the second connecting wall 707 is the same as that of the Figure 12The structure is identical to that described in [ 1 ]. Specifically, the second connecting wall 707 includes a downwardly open accommodating recess 707A. Accommodating recess 707A accommodates the swing connecting shaft 685B. The second connecting wall 707 is rotatable relative to the swing connecting shaft 685B. Specifically, the second connecting wall 707 and the second member 752 are connected to the extension member 685 in a state where they are rotatable about the central axis of the swing connecting shaft 685B.

[0357] The power unit 750 has an electric drive mechanism 755. The drive mechanism 755 is located near the center of the first member 751 in the reference axis direction 751L. Figure 17 As shown, the drive mechanism 755 is arranged at a position close to the fourth wall 751D relative to the reference axis 751V. Figure 16 As shown, the drive mechanism 755 has an electric motor 756 , a speed reducer 757 and a pinion 758 .

[0358] The electric motor 756 operates based on power supplied from a battery (not shown). The electric motor 756 includes a housing 756A and an output shaft 756B. The housing 756A is located outside the first member 751. The housing 756A is located above the first wall 751A of the first member 751. The output shaft 756B protrudes downward from the housing 756A. The output shaft 756B is cylindrical. The central axis of the output shaft 756B extends approximately in the Z direction. The output shaft 756B is rotatable relative to the housing 756A. The output shaft 756B rotates about its own central axis. In other words, the central axis of the output shaft 756B is the rotational central axis 756V of the electric motor 756. The output shaft 756B is rotatable in both forward and reverse directions based on the power supplied to the housing 756A.

[0359] The speed reducer 757 is located below the electric motor 756. The speed reducer 757 includes a speed reducer body 757A and a transmission shaft 757B. Similar to the electric motor 756, the speed reducer body 757A is located outside the first member 751 and above the first wall 751A of the first member 751. The speed reducer body 757A is fixed to the first wall 751A. The speed reducer body 757A is connected to the output shaft 756B of the electric motor 756. The torque of the output shaft 756B of the electric motor 756 is input into the speed reducer body 757A. The speed reducer body 757A amplifies the torque of the output shaft 756B of the electric motor 756 by a predetermined ratio and outputs it to the transmission shaft 757B. The transmission shaft 757B protrudes downward from the speed reducer body 757A. The transmission shaft 757B is cylindrical in shape. The central axis of the transmission shaft 757B is approximately aligned with the rotational axis 756V of the electric motor 756. In the Z direction, the portion of the transmission shaft 757B below the center is located within the first member 751. The transmission shaft 757B is rotatable relative to the reducer body 757A. The transmission shaft 757B rotates about its own central axis. The reducer 757 may be, for example, an eccentric oscillating gear type or a planetary gear type. Any type of reducer may be employed as long as it can amplify and output the torque from the electric motor 756.

[0360] The pinion 758 is located on the lower side relative to the speed reducer body 757A. In the Z direction, the pinion 758 is located between the first wall 751A and the second wall 751B in the first member 751. Figure 17 As shown, in the Y direction, the pinion 758 is configured to span the fourth wall 751D of the first member 751. That is, a portion of the pinion 758 is located outside the first member 751. The remaining portion of the pinion 758 enters the interior of the first member 751 through the communication port 751P of the fourth wall 751D. Figure 16As shown, the pinion gear 758 includes a gear body 758A and a plurality of pinion teeth 758B. The gear body 758A is cylindrical. The central axis of the gear body 758A is substantially consistent with the rotational center axis 756V of the electric motor 756. The transmission shaft 757B of the reducer 757 is disposed in the central hole of the gear body 758A. The gear body 758A is fixed to the transmission shaft 757B. The gear body 758A rotates integrally with the transmission shaft 757B. That is, the gear body 758A can rotate around an axis that is substantially orthogonal to the reference axis 751V. Furthermore, the gear body 758A is driven to rotate by the electric motor 756. The plurality of pinion teeth 758B protrude from the outer peripheral surface of the gear body 758A. The plurality of pinion teeth 758B are arranged at equal intervals along the circumferential direction centered on the central axis of the gear body 758A. Some of the plurality of pinion teeth 758B mesh with the rack teeth 752B of the second member 752. A gap, referred to as backlash, exists between the pinion teeth 758B and the rack teeth 752B.

[0361] The configuration of the driving mechanism 755 is described in detail. Figure 17 As shown, in the reference axis direction 751L, the imaginary line segment connecting the negative end 751W of the first member 751 and the positive end 752W of the second member 752 is referred to as the second line segment 680Y. When the excavator 680 is viewed from above in a direction parallel to the rotation center axis 610V, the rotation center axis 756V of the electric motor 756 and the center axis of the pinion 758 are located between the first line segment 680X and the second line segment 680Y. Figure 16 As shown, the negative end of the first member 751 is the end of the first member 751 on the opposite side to the side to be inserted into the second member 752. The power unit 750 is configured as described above.

[0362] The operation of the power unit 750 will be described. In the power unit 750, when the output shaft 756B of the electric motor 756 rotates, the pinion 758 rotates along with the rotation of the output shaft 756B. The pinion 758 rotates in either the forward or reverse direction according to the rotation direction of the output shaft 756B of the electric motor 756. The rotation of the pinion 758 is transmitted to the second member 752 through the engagement of the pinion teeth 758B with the rack teeth 752B. Furthermore, when the pinion 758 rotates, the second member 752 moves relative to the first member 751 in the reference axis direction 751L. That is, the second member 752 moves by the force received from the pinion 758. As Figure 16As shown by arrow 750V, the second member 752 moves in the positive direction or the negative direction relative to the first member 751 according to the rotation direction of the pinion 758. As the second member 752 moves, the protrusion amount of the second member 752 relative to the first member 751 increases or decreases. That is, the power unit 750 expands and contracts in the reference axis direction 751L. Figures 11 to 14 As described in , the extension and retraction of the power unit 750 drives the swing bracket 610 and the boom 530 to swing left and right.

[0363] Using the power unit 750 in the excavator 680 offers the following advantages. As described in (4-3) above, the collision between the bucket 550 and the excavation object can input a load from the outside into the boom 530. This load is referred to as the collision load. When the power unit 750 is used, the collision load can be transmitted to the second member 752 via the swing bracket 610 and the extension member 685. However, this collision load is hardly transmitted to the pinion 758, the speed reducer 757, and the electric motor 756 for two reasons. The first reason is that there is a gap between the rack teeth 752B of the second member 752 and the pinion teeth 758B of the pinion 758. Due to this gap, the collision load is not transmitted from the rack teeth 752B to the pinion teeth 758B and is dissipated. The second reason is that the extension direction of the second member 752 is approximately orthogonal to the central axis of the pinion 758. Therefore, the collision load acting on the second member 752 primarily has a component in the direction of the reference axis 751L, which is the extension direction of the second member 752. The collision load is unlikely to act as a force that causes each component to move in a direction that intersects the reference axis direction 751L. Therefore, the collision load acting on the second component 752 is unlikely to be transmitted as a force that causes the pinion 758 to move along the direction of its central axis. Therefore, the collision load acting on the second component 752 is unlikely to act as a force that causes the pinion 758, the speed reducer 757, and the electric motor 756 to move along the direction of their central axis. Figures 16 to 18 In the structure, the collision load acting on the second member 752 can be suppressed from reaching the speed reducer 757 and the electric motor 756. Figures 16 to 18 In the structure of , there is no need to provide a structure for receiving the collision load in the speed reducer 757 and the electric motor 756. Therefore, similarly to the content described in the second embodiment, for example, the size of the speed reducer 757 can be suppressed.

[0364] Furthermore, in the power unit 750, the drive mechanism 755 is located between the first line segment 680X and the second line segment 680Y. In other words, the drive mechanism 755 is positioned near the center of the housing portion 607 in the Y direction. In this case, even if the electric motor 756 or the speed reducer 757 has a slightly larger diameter, for example, it can still be accommodated within the housing portion 607. Consequently, the overall size of the excavator 680 can be made more compact.

[0365] In addition, the structure of the power unit 750 is not limited to Figures 16 to 18 The power unit 750 only needs to be configured to move the second member 752 relative to the first member 751 using a so-called rack and pinion mechanism. For example, in the power unit 750, the drive mechanism 755 can be configured from Figures 16 to 18 The example shown may be modified. For example, the drive mechanism 755 may be fixed to the housing 607 at a position further to the positive side than the positive end of the first member 751. Furthermore, the pinion 758 may mesh with the rack teeth 752B of the second member 752 at a position separated from the first member 751 in the reference axis direction 751L. Alternatively, the drive mechanism 755 may be located on the opposite side of the housing 607 from the center in the Y direction across the first member 751. In the drive mechanism 755, the center axis of the pinion 758 may intersect with the rotational center axis 756V of the electric motor 756. The reducer 757 may be omitted from the drive mechanism 755, and the pinion 758 may be attached to the output shaft 756B of the electric motor 756. The first member 751 is not limited to a rectangular cylindrical shape; any overall cylindrical shape is acceptable. The second member 752 is not limited to a rectangular columnar shape; any columnar shape extending along the reference axis direction 751L and having the rack teeth 752B on its outer surface may be acceptable.

[0366] <Fifth embodiment>

[0367] Below, use Figure 19 A fifth embodiment of a construction machine and an electric actuator for a construction machine will be described. In addition, it should be noted that the drawings sometimes enlarge the structural components to facilitate understanding. In addition, the dimensional ratios of the structural components may sometimes differ from the actual dimensional ratios or the dimensional ratios in other drawings. Figure 19 In, with Figures 1 to 18 Parts that perform the same or substantially the same function are marked with Figures 1 to 18 In the following description, the description of the parts that overlap with those of the first to fourth embodiments may be appropriately omitted or simplified.

[0368] like Figure 19As shown, the excavator 770 as a construction machine has a lower body 602, an upper body 606 as a vehicle body, a pair of travel devices 510, and a slewing bearing 603. The structure of the lower body 602, the pair of travel devices 510 and the slewing bearing 603 is the same as that of the second embodiment, so their description is omitted. The upper body 606 is the same as that of the second embodiment except that it does not have a support wall. In addition, Figure 19 In the figure, the riding part is omitted. The upper body 606 is located on the side opposite to the ground relative to the lower body 602. In this embodiment, up, down, left, right, front and back are defined in the same way as in the second embodiment. Figure 19 In the figure, for the convenience of explanation, some components of the excavator 770 are shown in cross section.

[0369] Excavator 770 as an excavation machine includes a boom 530, an arm 540, and a bucket 550. Boom 530, arm 540, and bucket 550 are located forward relative to upper body 606. The structures of boom 530, arm 540, and bucket 550 are the same as those of the second embodiment, and therefore, their description is omitted.

[0370] <Boom swing mechanism>

[0371] like Figure 19 As shown, the excavator 770 includes a boom swing mechanism 770A. The boom swing mechanism 770A is a mechanism for swinging the boom 530 left and right relative to the upper body 606. The boom swing mechanism 770A constitutes an electric actuator.

[0372] The boom swing mechanism 770A has a mounting wall 772. The mounting wall 772 is, for example, in the shape of a quadrilateral plate. The mounting wall 772 is located on the front side relative to the accommodating portion 607 of the upper body 606. The mounting wall 772 protrudes from the front surface 607F of the accommodating portion 607 toward the front side. The mounting wall 772 is fixed to the front surface 607F of the accommodating portion 607. The main surface of the mounting wall 772 faces up and down. The main surface is the surface with the largest area in a plate-shaped object. The mounting wall 772 has a through hole 772A. The through hole 772A penetrates the mounting wall 772 from top to bottom. The central axis of the through hole 772A extends approximately in the Z direction.

[0373] The boom swing mechanism 770A includes a swing bracket 774. The swing bracket 774 is located on the upper side relative to the mounting wall 772. The swing bracket 774 is in the shape of a circular plate. The swing bracket 774 is located on the upper surface of the mounting wall 772. The main surface of the swing bracket 774 faces up and down. The area of the main surface of the swing bracket 774 is larger than the opening area of the through hole 772A of the mounting wall 772. In addition, the swing bracket 774 covers the through hole 772A of the mounting wall 772. The swing bracket 774 is slidable relative to the mounting wall 772. In addition, the swing bracket 774 is arranged at a position separated from the front surface 607F of the accommodating portion 607. The base wall 534 of the boom 530 is fixed to the upper surface of the swing bracket 774. Similar to the second embodiment, the boom body 531 is connected to the base wall 534 via the connecting shaft 532. The boom body 531 is rotatable up and down about the connecting shaft 532 as a rotation center.

[0374] The boom swing mechanism 770A includes a drive device 780 . The drive device 780 is located on the lower side relative to the mounting wall 772 . The drive device 780 includes an electric motor 781 and a speed reducer 782 .

[0375] The electric motor 781 includes a housing 781A and an output shaft 781B. The electric motor 781 is operated by power supplied by a battery (not shown). The housing 781A has a cylindrical outer shape. The central axis of the housing 781A extends approximately in the Z direction. The output shaft 781B protrudes upward from the housing 781A. The central axis of the output shaft 781B is approximately aligned with the central axis of the housing 781A. The output shaft 781B is rotatable relative to the housing 781A. The output shaft 781B rotates about its own central axis. The output shaft 781B can rotate in both forward and reverse directions depending on the power supplied to the housing 781A.

[0376] The reducer 782 is located above the electric motor 781. The reducer 782 includes a reducer body 782A, an output member 782B, and an extension 782C. The reducer body 782A has a cylindrical shape. The central axis of the reducer body 782A is substantially aligned with the central axis of the housing 781A of the electric motor 781. The reducer body 782A is connected to the output shaft 781B of the electric motor 781. Furthermore, the torque of the output shaft 781B of the electric motor 781 is input into the reducer body 782A. The reducer body 782A amplifies the torque of the output shaft 781B of the electric motor 781 by a predetermined ratio and outputs it to the output member 782B. The output member 782B is located above the reducer body 782A. The output member 782B is cylindrical. The diameter of the output member 782B is smaller than that of the reducer body 782A. The central axis of the output member 782B is substantially aligned with the central axis of the reducer body 782A. The output member 782B is rotatable relative to the reducer body 782A. The output member 782B rotates about its own central axis. The central axis of the output member 782B constitutes the rotational central axis 780V of the drive unit 780. That is, the output member 782B and the drive unit 780 output torque centered about the rotational central axis 780V. The extension 782C protrudes from the outer peripheral surface of the reducer body 782A. The extension 782C is located in the upper portion of the reducer body 782A. The extension 782C extends across the entire area of the reducer body 782A in a circumferential direction centered about the central axis of the reducer body 782A. That is, the extension 782C is annular. The reducer 782 may be, for example, an eccentric oscillating gear type or a planetary gear type. The reducer 782 may be any type of reducer as long as it is capable of amplifying and outputting the torque from the electric motor 781.

[0377] The boom swing mechanism 770A includes a transmission member 783. The transmission member 783 is located above the reducer 782. The transmission member 783 is located within the through-hole 772A of the mounting wall 772. The transmission member 783 is cylindrical in shape. The diameter of the transmission member 783 is smaller than the diameter of the through-hole 772A. The center axis of the transmission member 783 is approximately aligned with the rotation center axis 780V of the drive unit 780. The lower end surface of the transmission member 783 is fixed to the upper end surface of the output member 782B of the reducer 782. The upper end surface of the transmission member 783 is fixed to the lower surface of the swing bracket 774. In other words, the transmission member 783 and the swing bracket 774 are aligned with the drive unit 780 in a direction along the rotation center axis 780V and are located on the rotation center axis 780V of the drive unit 780. Furthermore, the transmission member 783 rotates integrally with the output member 782B and the swing bracket 774. Thus, the transmission member 783 is located between the drive device 780 and the swing bracket 774, transmitting the torque of the drive device 780 to the swing bracket 774. Furthermore, the swing bracket 774 receives the torque from the drive device 780 via the transmission member 783, thereby rotating about the rotational axis 780V. Furthermore, as described above, the transmission member 783 connects the drive device 780 and the swing bracket 774. Furthermore, the swing bracket 774 is supported by the upper surface of the mounting wall 772. As a result, the drive device 780 is suspended from the lower surface of the swing bracket 774. Furthermore, the drive device 780 is supported from above by the swing bracket 774. The drive device 780 is mounted to the accommodating portion 607 via the swing bracket 774 and the mounting wall 772. Alternatively, it can be said that the swing bracket 774 is supported by the upper surface of the mounting wall 772, thereby being connected to the accommodating portion 607 so as to be rotatable about the rotational axis 780V.

[0378] The boom swing mechanism 770A includes a first bearing 776. The first bearing 776 is located within the through-hole 772A of the mounting wall 772. It is located between the inner surface of the through-hole 772A and the transmission member 783. The first bearing 776 is located in the lower portion of the through-hole 772A. The first bearing 776 is annular overall. It is a so-called rolling bearing. Although not shown, the first bearing 776 comprises an annular inner ring, an annular outer ring, and multiple rolling elements. The outer diameter of the inner ring is smaller than the inner diameter of the outer ring. The central axis of the inner ring is approximately aligned with the central axis of the outer ring. The inner ring is radially inward of the outer ring about its own central axis. Multiple rolling elements are located between the inner and outer rings. These rolling elements may be spherical or cylindrical, for example. These rolling elements guide the rotation of the inner ring relative to the outer ring. The transmission member 783 extends through the central hole of the inner ring. The inner circumferential surface of the inner ring is fixed to the transmission member 783. The inner ring rotates integrally with the transmission member 783. The outer circumferential surface of the outer ring is fixed to the inner surface of the through-hole 772A of the mounting wall 772. Specifically, the first bearing 776 is mounted to the housing 607 of the upper body 606 via the mounting wall 772. Furthermore, the first bearing 776 supports the transmission member 783 so that it can rotate relative to the mounting wall 772.

[0379] The boom swing mechanism 770A includes a second bearing 777. Like the first bearing 776, the second bearing 777 is located between the inner surface of the through-hole 772A of the mounting wall 772 and the transmission member 783. The second bearing 777 is located above the first bearing 776. The second bearing 777 and the first bearing 776 are aligned in the Z direction and along the rotational axis 780V of the drive unit 780. The structure of the second bearing 777 is identical to that of the first bearing 776. Therefore, a detailed description of the second bearing 777 will be omitted. The second bearing 777 supports the transmission member 783 so that it can rotate.

[0380] The boom swing mechanism 770A includes a retaining member 784. Relative to the mounting wall 772, the retaining member 784 is located on the lower side. That is, along the rotational center axis 780V of the electric motor 781, the retaining member 784 is located on the opposite side of the swing bracket 774, separated by the first bearing 776 and the second bearing 777. The retaining member 784 is positioned away from the mounting wall 772. Furthermore, the retaining member 784 is positioned away from the front surface 607F of the accommodating portion 607. The retaining member 784 is in the shape of a quadrilateral plate. The main surface of the retaining member 784 faces upward and downward. The retaining member 784 includes a accommodating hole 784A. The accommodating hole 784A extends through the retaining member 784 from top to bottom. The center axis of the accommodating hole 784A is approximately aligned with the rotational center axis 780V of the drive unit 780. The diameter of the accommodating hole 784A is approximately aligned with the diameter of the reducer body 782A of the drive unit 780. The speed reducer body 782A passes through the accommodation hole 784A. The upper surface of the holding member 784 faces the extension portion 782C of the speed reducer 782. The holding member 784 and the extension portion 782C of the speed reducer 782 are fixed with bolts 789.

[0381] The boom swing mechanism 770A has a buffer member 786. The buffer member 786 is located between the front surface 607F of the accommodating portion 607 and the rear end surface 784N of the retaining member 784. The buffer member 786 is a coil spring. The elastic modulus of the buffer member 786 is smaller than the elastic modulus of the retaining member 784. That is, the buffer member 786 is made of a material that is softer than the retaining member 784. One end of the buffer member 786 is mounted on the front surface 607F of the accommodating portion 607. The other end of the buffer member 786 is mounted on the rear end surface 784N of the retaining member 784. That is, the buffer member 786 connects the retaining member 784 and the accommodating portion 607. In addition, the buffer member 786 is mounted to the object using a mounting member such as a hook.

[0382] <Function of the Fifth Embodiment>

[0383] In the excavator 770, when the output shaft 781B of the electric motor 781 rotates, the swing bracket 774 rotates together with the transmission member 783. Then, when the swing bracket 774 rotates, the boom 530 swings left and right.

[0384] <Effects of the Fifth Embodiment>

[0385] (5-1) As described in the operation of the above embodiment, in the excavator 770 of this embodiment, the boom 530 can be swung left and right using the electric motor 781 as a driving source.

[0386] As described in the first embodiment, a load can be input from the outside into the boom 530 due to a collision between the bucket 550 and the excavation object. This load is referred to as a collision load. In the excavator 770 of this embodiment, the collision load can be transmitted to the transmission member 783 via the swing bracket 774. The collision load transmitted to the transmission member 783 can, for example, act as a force that causes the transmission member 783 to move radially outward about its central axis. This collision load can basically be transmitted to the accommodation portion 607 via the first bearing 776 and the second bearing 777. Furthermore, the collision load can be absorbed by the accommodation portion 607.

[0387] On the other hand, a portion of the collision load transmitted to the transmission member 783 can also be transmitted from the transmission member 783 to the drive device 780. In addition to this collision load, the drive device 780 is also subjected to the following reaction torque. Specifically, when the swing bracket 774 and the boom 530 are swung by driving the electric motor 781, a reaction force generated by the rotation of the swing bracket 774 is applied to the drive device 780. Hereinafter, the collision load and reaction torque input to the drive device 780 are collectively referred to as specific loads.

[0388] Here, the driving device 780 is held by a holding member 784. Assume that the holding member 784 is fixed to the front surface 607F of the accommodating portion 607. In this case, when the driving device 780 operates in response to a specific load input to the driving device 780, the specific load cannot be released from the driving device 780 because the driving device 780 cannot move.

[0389] In contrast, in the structure of the present embodiment, the retaining member 784 is arranged at a position separated from the accommodating portion 607. Therefore, when the drive device 780 operates in response to the input of a specific load, the retaining member 784 allows the drive device 780 to operate. That is, in the structure of the present embodiment, the drive device 780 operates in accordance with the specific load, thereby being able to release the specific load from the drive device 780. Furthermore, in the structure of the present embodiment, the buffer member 786 is located between the retaining member 784 and the accommodating portion 607. The buffer member 786 attenuates the operation of the drive device 790 in accordance with the specific load through its own elastic force. In such a structure of the present embodiment, the burden on the drive device 780 can be effectively suppressed. Therefore, in the structure of the present embodiment, there is no need to provide a structure for bearing a specific load in the reducer 782 and the electric motor 781. For example, this helps to suppress the increase in size of the reducer 782.

[0390] (5-2) The excavator 770 of this embodiment includes two bearings: a first bearing 776 and a second bearing 777. The transmission member 783 is supported by these two bearings. Therefore, when a collision load acts on the transmission member 783 via the boom 530 and the swing bracket 774, the collision load is distributed across these two bearings. This reduces the collision load input to each bearing, thus minimizing the burden on each bearing.

[0391] <Modification of Fifth Embodiment>

[0392] The fifth embodiment can be modified and implemented as follows: The first to fifth embodiments and the following modified examples can be combined and implemented within a range that does not technically conflict with each other.

[0393] The structure of the transmission member 783 is not limited to the example of the above embodiment. The transmission member 783 only needs to be able to transmit the torque of the drive device 780 to the swing bracket 774. For example, the shape of the transmission member 783 can be changed from the example of the above embodiment. For example, the transmission member 783 can also be a cylindrical shape with steps. The transmission member 783 can also be treated as a single component with the output member 782B of the speed reducer 782. In other words, the output member 782B of the speed reducer 782 can be used as the transmission member 783, or the transmission member 783 can be used as the output member 782B of the speed reducer 782.

[0394] The number of bearings supporting the transmission member 783 is not limited to the example of the above embodiment, and the number of bearings may be one or three or more.

[0395] The structure of the bearing is not limited to the examples in the above embodiment. For example, the bearing may be a sliding bearing. If a sliding bearing is used as the bearing, the through hole 772A of the mounting wall 772 itself may function as the sliding surface of the bearing. In this case, the mounting wall 772 includes the bearing.

[0396] The structure for mounting the bearing in the housing 607 is not limited to the example in the above embodiment. For example, the shape of the mounting wall 772 may be modified from the example in the above embodiment. The mounting wall 772 only needs to be configured to hold the bearing and be fixed to the housing 607. The bearing may also be mounted in the housing 607 using a structure other than an integral wall such as the mounting wall 772. In other words, the mounting wall 772 is not essential.

[0397] The object to which the bearing is mounted does not need to be the accommodation portion 607. The bearing only needs to be mounted somewhere on the vehicle body.

[0398] The buffer member 786 is not limited to the above-mentioned embodiment. The buffer member 786 only needs to be made of a material softer than the retaining member 784. For example, the buffer member 786 may be a member made of rubber. Such a rubber object may also be located between the retaining member 784 and the front surface 607F of the accommodating portion 607. In addition, for example, Figure 20 The buffer member 787 shown is shown. The material of the buffer member 787 only needs to be softer than that of the retaining member 784, and can be, for example, metal or resin. When viewed from the Y direction, the buffer member 787 is configured in an L-shape. That is, the buffer member 787 has a bottom plate portion 787A corresponding to the horizontal side of the L-shape and a contact portion 787B corresponding to the vertical side of the L-shape. The bottom plate portion 787A is, for example, in the shape of a square plate. The main surface of the bottom plate portion 787A faces up and down. The rear end of the bottom plate portion 787A is fixed to the front surface 607F of the accommodating portion 607. The contact portion 787B rises upward from the end of the bottom plate portion 787A on the side opposite to the accommodating portion 607. The contact portion 787B is, for example, in the shape of a square plate. The main surface of the contact portion 787B faces forward and backward. The upper portion of the contact portion 787B is fixed to the rear end surface 784N of the retaining member 784. When such a buffer member 787 is used, when a specific load is input to the drive device 780 and the retaining member 784 operates together with the drive device 780, the contact portion 787B moves back and forth starting from the connection portion with the bottom plate portion 787A. Thus, similar to the above (5-1), the specific load input to the drive device 780 can be attenuated. Figure 20 In the Figure 19 Parts that perform the same or substantially the same function are marked with Figure 19 In addition, Figure 19 Likewise, in Figure 20 A portion of a component is shown through a cross section.

[0399] The buffer member 786 may be connected to a portion of the vehicle body other than the storage portion 607 on the side opposite to the holding member 784. The buffer member 786 only needs to be connected to a portion of the vehicle body.

[0400] The structure of the swing bracket 774 is not limited to the example in the above embodiment. The swing bracket 774 can be fixed to the boom 530 and rotated by receiving torque from the drive device 780. For example, the shape of the swing bracket 774 can be modified from the example in the above embodiment. For example, the swing bracket 774 can also be in the shape of a polygonal plate.

[0401] The fixing position of the boom 530 to the swing bracket 774 is not limited to the example of the above embodiment. The boom 530 may be fixed to any position in the swing bracket 774.

[0402] The structure of the holding member 784 is not limited to the example of the above embodiment. The holding member 784 only needs to have a receiving hole 784A through which the drive device 780 passes. The holding member 784 may also be in the shape of a circular plate or a polygonal plate other than a quadrilateral.

[0403] The components of the drive device 780 that extend through the receiving hole 784A of the retaining member 784 are not limited to those in the above embodiment. Specifically, portions of the drive device 780 other than the speed reducer body 782A may extend through the receiving hole 784A. For example, the electric motor 781 may extend through the receiving hole 784A.

[0404] The positional relationship between the holding member 784 and the swing bracket 774 is not limited to the example in the above embodiment. The holding member 784 and the swing bracket 774 may be located on opposite sides of the bearing that supports the transmission member 783. For example, the overall structure of the boom swing mechanism 770A may be modified so that the holding member 784 is located above the bearing and the swing bracket 774 is located below the bearing.

[0405] The structure of the drive device 780 is not limited to the example of the above-mentioned embodiment. For example, in the drive device 780, the outer shape of the housing 781A of the electric motor 781 can also be changed from the example of the above-mentioned embodiment. The speed reducer 782 can also be omitted from the drive device 780. In the case where the speed reducer 782 is omitted from the drive device 780, the central axis of the output shaft 781B of the electric motor 781 constitutes the rotational center axis of the drive device 780. The drive device 780 only needs to include the electric motor 781 and output torque centered on the rotational center axis. The rotational center axis of the torque output by the drive device 780 only needs to extend above and below the vehicle body as a whole. For example, it may be inclined within a range of about 15 degrees relative to the Z direction.

[0406] The drive unit 780 may be cylindrical. When the drive unit 780 is cylindrical, the same effect as (5-1) can be obtained by omitting the bearing and the mounting wall 772 and adopting a columnar member that passes through the drive unit 780. Figure 21 An example of a boom swing mechanism 770B when such a structure is adopted will be described. As in the above embodiment, the boom swing mechanism 770B constitutes an electric actuator. Figure 21 In, with Figure 19 Parts that perform the same or substantially the same function are marked with Figure 19 In addition, Figure 19 Likewise, in Figure 21 A portion of a component is shown through a cross section.

[0407] like Figure 21 As shown, the boom swing mechanism 770B includes a flange wall 794. The flange wall 794 protrudes forward from the front surface 607F of the housing portion 607 of the upper body 606. The flange wall 794 is fixed to the front surface 607F of the housing portion 607. The flange wall 794 is, for example, in the shape of a square plate. The main surface of the flange wall 794 faces upward and downward.

[0408] The boom swing mechanism 770B includes a sliding plate 796. The sliding plate 796 is located on the upper surface of the flange wall 794. The sliding plate 796 is annular. The central axis of the sliding plate 796 extends substantially in the Z direction. Furthermore, the outer surface of the sliding plate 796 is processed to reduce frictional resistance.

[0409] The boom swing mechanism 770B includes a drive device 790 . The drive device 790 is located above the slide plate 796 . The drive device 790 includes an electric motor 791 and a speed reducer 792 .

[0410] The electric motor 791 is powered by a battery (not shown). The electric motor 791 includes a housing 791A and an output shaft 791B. The housing 791A is cylindrical. The inner diameter of the housing 791A is approximately identical to the inner diameter of the sliding plate 796. The outer diameter of the housing 791A is approximately identical to the outer diameter of the sliding plate 796. The central axis of the housing 791A is approximately identical to the central axis of the sliding plate 796. The downward end surface of the housing 791A is fixed to the upper surface of the sliding plate 796. The output shaft 791B protrudes upward from the housing 791A. The output shaft 791B is cylindrical. The inner diameter of the output shaft 791B is slightly larger than the inner diameter of the housing 791A. The outer diameter of the output shaft 791B is smaller than the outer diameter of the housing 791A. The central axis of the output shaft 791B is approximately identical to the central axis of the housing 791A. The output shaft 791B is rotatable relative to the housing 791A. The output shaft 791B rotates about its own central axis and can rotate in both forward and reverse directions according to the power supplied to the housing 791A.

[0411] The reducer 792 is located above the electric motor 791. The reducer 792 includes a reducer body 792A, an output member 792B, and an extension 792C. The reducer body 792A is cylindrical. The inner diameter of the reducer body 792A is substantially identical to the inner diameter of the housing 791A of the electric motor 791. The outer diameter of the reducer body 792A is substantially identical to the outer diameter of the housing 791A of the electric motor 791. The central axis of the reducer body 792A is substantially identical to the central axis of the electric motor 791. The lower end face of the reducer body 792A is fixed to the upper end face of the housing 791A of the electric motor 791. The reducer body 792A is connected to the output shaft 791B of the electric motor 791. Furthermore, the torque of the output shaft 791B of the electric motor 791 is input into the reducer body 792A. The speed reducer body 792A amplifies the torque of the output shaft 791B of the electric motor 791 at a predetermined ratio and outputs the amplified torque to the output member 792B.

[0412] The output member 792B is located above the reducer body 792A. The output member 792B constitutes the output member of the drive device 790. The output member 792B is cylindrical. The inner diameter of the output member 792B is substantially identical to the inner diameter of the reducer body 792A. The outer diameter of the output member 792B is smaller than the outer diameter of the reducer body 792A. The central axis of the output member 792B is substantially identical to the central axis of the reducer body 792A. The output member 792B is rotatable relative to the reducer body 792A. The output member 792B rotates about its own central axis. The central axis of the output member 792B constitutes the rotational center axis 790V of the drive device 790. That is, the output member 792B and the drive device 790 output torque centered about the rotational center axis 790V.

[0413] The extension 792C protrudes from the outer circumference of the reducer body 792A. The extension 792C is located in the upper portion of the reducer body 792A. The extension 792C extends across the entire reducer body 792A in a circumferential direction centered on the central axis of the reducer body 792A. In other words, the extension 792C is annular.

[0414] The speed reducer 792 is constructed as described above. For example, the speed reducer 792 may be an eccentric oscillating gear type or a planetary gear type. Any type of speed reducer may be employed as long as it can amplify and output the torque from the electric motor 791. Furthermore, the drive unit 790, which includes the speed reducer 792 and the electric motor 791, is positioned above the flange wall 794. Furthermore, the drive unit 790 is supported from below by the flange wall 794.

[0415] The boom swing mechanism 770B includes a swing bracket 774. The swing bracket 774 is located above the output member 792B of the speed reducer 792. The swing bracket 774 is plate-shaped. The outer shape of the swing bracket 774 can be circular or polygonal. The main surface of the swing bracket 774 faces up and down. The swing bracket 774 extends forward and backward, spanning the drive unit 790. The front end of the swing bracket 774 is further forward than the front end of the drive unit 790. The rearward portion of the lower surface of the swing bracket 774 faces the upper end surface of the output member 792B of the speed reducer 792. Furthermore, the lower surface of the swing bracket 774 is fixed to the output member 792B of the speed reducer 792. Therefore, the swing bracket 774 rotates integrally with the output member 792B. That is, the swing bracket 774 receives torque from the drive unit 790 and rotates about the rotation center axis 790V. Furthermore, the base wall 534 of the boom 530 is fixed to the front portion of the upper surface of the swing bracket 774. The swing bracket 774 has a through hole 774H. The through hole 774H is located in the rear portion of the swing bracket 774. The center axis of the through hole 774H is substantially aligned with the rotation center axis 790V of the drive unit 790. The diameter of the through hole 774H is substantially aligned with the inner diameter of the output member 792B in the speed reducer 792. As described above, the swing bracket 774 is located on the upper side relative to the drive unit 790. That is, in the direction along the rotation center axis 790V of the drive unit 790, the swing bracket 774 is located on the side opposite to the flange wall 794 relative to the drive unit 790.

[0416] The boom swing mechanism 770B includes a fixed wall 795. The fixed wall 795 is located above the swing bracket 774. The fixed wall 795 is spaced apart from the swing bracket 774. The fixed wall 795 protrudes forward from the front surface 607F of the accommodating portion 607 of the upper body 606. The fixed wall 795 is fixed to the front surface 607F of the accommodating portion 607. The fixed wall 795 has, for example, a rectangular plate shape. The main surface of the fixed wall 795 faces upward and downward.

[0417] As described above, in the boom swing mechanism 770B, the flange wall 794, the slide plate 796, the drive unit 790, the swing bracket 774, and the fixed wall 795 are arranged along the rotation axis 790V of the drive unit 790. These components are located on the rotation axis 790V of the drive unit 790.

[0418] The boom swing mechanism 770B includes a pin 797. Pin 797 extends downward from the fixed wall 795. Pin 797 is cylindrical. The diameter of pin 797 is smaller than the diameter of the through-hole 774H of the swing bracket 774. The central axis of pin 797 extends in the Z direction. The upper end of pin 797 passes through the fixed wall 795. Pin 797 is fixed to the fixed wall 795. In other words, pin 797 cannot move or rotate relative to the fixed wall 795. The lower end of pin 797 passes through the flange wall 794. Pin 797 is fixed to the flange wall 794. In other words, pin 797 cannot move or rotate relative to the flange wall 794. A portion of pin 797, midway along its central axis, passes through the through-hole 774H of the swing bracket 774, the center hole 792H of the speed reducer 792, the center hole 791H of the electric motor 791, and the center hole of the slide plate 796. As a result of this structure, the driving device 790 is mounted to the accommodating portion 607 via the pin 797, the flange wall 794, and the fixed wall 795. From another perspective, the swing bracket 774 is connected to the accommodating portion 607 via the pin 797, the driving device 790, and the flange wall 794 so as to be rotatable about the rotation center axis 780V.

[0419] The boom swing mechanism 770B has a holding member 784. The holding member 784 is located between the swing bracket 774 and the flange wall 794. The holding member 784 is arranged at a position separated from the front surface 607F of the accommodating portion 607. The structure and combination of the holding member 784 Figure 19 The structure is the same as that described above. Specifically, the holding member 784 is plate-shaped and has a receiving hole 784A. The speed reducer main body 792A of the driving device 790 passes through the receiving hole 784A. The holding member 784 is fixed to the extension portion 792C of the speed reducer 792 by bolts 789.

[0420] The boom swing mechanism 770B has a buffer member 786. The buffer member 786 connects the rear end surface 784N of the holding member 784 and the front surface 607F of the accommodating portion 607. The structure and combination of the buffer member 786 Figure 19 The structure is the same as that already described.

[0421] The boom swing mechanism 770B can swing the boom 530 left and right using the electric motor 791 as a driving source. Specifically, when the output shaft 791B of the electric motor 791 rotates, the swing bracket 774 rotates. As a result, the boom 530 and the swing bracket 774 swing left and right together.

[0422] If combined Figure 19 As described above, a specific load including the collision load of the boom 530 and the reaction torque from the swing bracket 774 can be input to the driving device 790. Figure 19Similarly to the structure shown, in the boom swing mechanism 770B, the specific load can be released from the drive device 790. That is, in the boom swing mechanism 770B, the retaining member 784 that retains the drive device 790 is arranged at a position separated from the accommodating portion 607. In addition, there is a gap between the outer peripheral surface of the pin 797 that passes through the drive device 790 and the inner peripheral surface of the drive device 790. Therefore, when the drive device 790 is to move in response to the input of a specific load, the retaining member 784 allows the drive device 790 to move. Specifically, the retaining member 784 allows the drive device 790 to rotate around the pin 797. On the other hand, such movement of the drive device 790 is gradually attenuated by the elastic force of the buffer member 786. Therefore, when the boom swing mechanism 770B is adopted, the same effect as (5-1) can be obtained.

[0423] In addition, the structure of the boom swing mechanism 770B is not limited to Figure 21 The example shown. The boom swing mechanism 770B only needs to be configured to hold the drive unit 790 and the swing bracket 774 via the pin 797. For example, the electric motor 791 only needs to be cylindrical and is not limited to a circular cylindrical shape. Similarly, the reducer 792 only needs to be cylindrical and is not limited to a circular cylindrical shape. The size relationship between the diameters of the electric motor 791 and the reducer 792 is not limited to the above example. The inner diameters of the electric motor 791 and the reducer 792 only need to be set so that the pin 797 can be inserted. The reducer 792 can also be omitted from the drive unit 790. Furthermore, the output shaft 791B of the electric motor 791 can serve as the output member of the drive unit 790. The rotational center axis of the torque output by the drive unit 790 can be tilted with respect to the Z direction. The fixing wall 795 and the flange wall 794 do not need to be fixed to the front surface 607F of the accommodating portion 607. The fixing wall 795 and the flange wall 794 can be fixed to any part of the vehicle body. The flange wall 794 may be shaped appropriately as long as it is configured to support the drive unit 790. The pin 797 is not limited to being cylindrical, as long as it can penetrate the drive unit 790. Figure 19 The above-described modification examples are appropriately applied to the boom swing mechanism 770B. For example, the structure of the buffer member 786, the structure of the holding member 784, and the structure of the swing bracket 774 are not limited to Figure 21 In the example shown, the sliding plate 796 and the fixed wall 795 may be omitted in the boom swing mechanism 770B. Furthermore, the buffer member 786 may be omitted in the boom swing mechanism 770B.

[0424] In excavator 770, slewing bearing 603 is not essential. Specifically, depending on the structure of excavator 770, upper body 606 may not be able to swivel relative to lower body 602, and upper body 606 and lower body 602 may be integrally formed. In this case, upper body 606 and lower body 602 constitute the vehicle body. That is, the vehicle body is not limited to the example in the above embodiment.

[0425] The construction machine to which the boom swing mechanisms 770A and 770B, which are electric actuators, are applied is not limited to the excavator 770 .

[0426] In the above embodiment, various mechanisms can be used to fix the two members. Examples of the mechanism to fix the two members include bolt fastening, welding, integral molding, spline connection, and the like.

[0427] In the above embodiment, a portion composed of multiple objects may be integrated into the multiple objects, and conversely, a portion composed of one object may be divided into multiple objects. Regardless of integration or not, it is sufficient as long as the purpose of the present invention can be achieved.

[0428] <Sixth embodiment>

[0429] Below, use Figure 22 and Figure 23 A sixth embodiment of a construction machine and an electric actuator for a construction machine will be described. It should be noted that the drawings sometimes enlarge the structural components to facilitate understanding. In addition, the dimensional ratios of the structural components may sometimes differ from the actual dimensional ratios or the dimensional ratios in other drawings. Figure 22 and Figure 23 In, with Figures 1 to 21 Parts that perform the same or substantially the same function are marked with Figures 1 to 21 For ease of explanation, Figure 23 In the following description, the description of the parts that overlap with those of the first to fifth embodiments may be appropriately omitted or simplified.

[0430] like Figure 22As shown, the excavator 800 as a construction machine has a lower body 602, an upper body 606 as a vehicle body, a pair of travel devices 510, and a slewing bearing 603. The structures of the lower body 602, the pair of travel devices 510, and the slewing bearing 603 are the same as those in the second embodiment. Therefore, their description is omitted. The structure of the upper body 606 is the same as that in the second embodiment. That is, the upper body 606 has a rectangular shaped accommodation portion 607, a riding portion located on the upper side relative to the accommodation portion 607, and a support wall portion 609 protruding from the front surface 607F of the accommodation portion 607 toward the front side. In addition, the support wall portion 609 has a through hole 609A that passes through in approximately the Z direction. The center axis of the through hole 609A constitutes the rotation center axis 610V of the boom 530. In addition, Figure 22 , the riding portion is omitted. The upper body 606 is located on the side opposite to the ground relative to the lower body 602. In this embodiment, up, down, left, right, front, and back are defined in the same manner as in the second embodiment.

[0431] Excavator 800, as an excavation machine, includes a boom 530, an arm 540, and a bucket 550. Boom 530, arm 540, and bucket 550 are located forward relative to upper body 606. The structures of boom 530, arm 540, and bucket 550 are the same as those of the second embodiment. Therefore, their description will be omitted.

[0432] <Boom swing mechanism>

[0433] like Figure 22 As shown, the excavator 800 includes a boom swing mechanism 800A. The boom swing mechanism 800A is a mechanism for swinging the boom 530 left and right relative to the upper body 606. The boom swing mechanism 800A constitutes an electric actuator.

[0434] The boom swing mechanism 800A includes a swing bracket 610 and a pin 620. The structures of the swing bracket 610 and the pin 620 are basically the same as those of the second embodiment. Figure 22 As shown, the swing bracket 610 has an upper wall 611, a lower wall 612 located on the lower side relative to the upper wall 611, and a connecting wall 613 connecting the upper wall 611 and the lower wall 612. The base wall 534 of the movable arm 530 is fixed to the connecting wall 613. The following contents of the swing bracket 610 of this embodiment are different from those of the second embodiment. That is, in the swing bracket 610 of this embodiment, the dimension of the lower wall 612 in the Z direction is larger than the dimension of the upper wall 611 in the Z direction. Moreover, in the Z direction, the lower surface 612D of the lower wall 612 is located further downward than the lower surface 607D of the accommodating portion 607 of the upper body 606. Except for this feature of the lower wall 612, the structure of the swing bracket 610 is the same as that of the second embodiment. Therefore, further description of the swing bracket 610 is omitted.

[0435] The swing bracket 610 is connected to the support wall portion 609 of the upper body 606 via the pin 620. That is, the pin 620 passes through the through hole 609A of the support wall portion 609 and passes through the upper wall 611 and the lower wall 612. Figure 22 , the gap between the pin 620 and the through-hole 609A is shown in an exaggerated manner. Similar to the second embodiment, the pin 620 is in a state where it can rotate relative to the through-hole 609A. The pin 620 is supported by the through-hole 609A so as to rotate around the rotation center axis 610V, which is the central axis of the through-hole 609A. On the other hand, the pin 620 is fixed to the upper wall 611 and the lower wall 612. Therefore, when the pin 620 rotates around the rotation center axis 610V, the upper wall 611 and the lower wall 612 rotate integrally with the pin 620. That is, the swing bracket 610 can rotate around the rotation center axis 610V.

[0436] The boom swing mechanism 800A includes a drive unit 615. The entire drive unit 615 is located inside the housing 607. The drive unit 615 is located near the front of the housing 607. The structure of the drive unit 615 is the same as that of the second embodiment. Therefore, the following description will only briefly describe the drive unit 615.

[0437] The drive device 615 includes an electric motor 616, a speed reducer 617, and a transmission shaft 618. The electric motor 616 has a housing 616A and an output shaft 616B. The housing 616A is fixed to the inner wall of the accommodating portion 607. The output shaft 616B protrudes downward from the housing 616A. The output shaft 616B is cylindrical. The central axis of the output shaft 616B extends generally in the Z direction. The central axis of the output shaft 616B is generally parallel to the aforementioned rotational center axis 610V of the swing bracket 610. The output shaft 616B is rotatable relative to the housing 616A.

[0438] The speed reducer 617 is located below the electric motor 616. The speed reducer 617 is fixed to the inner wall of the housing 607. The torque of the output shaft 616B of the electric motor 616 is input to the speed reducer 617. The speed reducer 617 amplifies the torque of the output shaft 616B of the electric motor 616 at a predetermined ratio and outputs it. The speed reducer 617 may be, for example, an eccentric oscillating gear type or a planetary gear type. Any type of speed reducer may be employed as long as it is capable of amplifying and outputting the torque from the electric motor 616.

[0439] The transmission shaft 618 is located downwardly relative to the speed reducer 617. A portion of the transmission shaft 618 protrudes downwardly from the lower surface 607D of the accommodating portion 607. The transmission shaft 618 is cylindrical. The central axis of the transmission shaft 618 is substantially aligned with the central axis of the output shaft 616B of the electric motor 616. The transmission shaft 618 receives torque from the speed reducer 617 and rotates about its own central axis. That is, when the central axis of the transmission shaft 618 is set as the rotation center axis 615V, the transmission shaft 618 and the drive device 615 output torque centered about the rotation center axis 615V.

[0440] The boom swing mechanism 800A has a pinion 809. The pinion 809 is mounted on the transmission shaft 618. Figure 23 As shown, the pinion 809 has a main body 809A and a plurality of teeth 809B. The main body 809A is cylindrical. The central axis of the main body 809A is roughly consistent with the rotation center axis 615V. The transmission shaft 618 is arranged in a hole in the center of the main body 809A. The main body 809A is fixed to the transmission shaft 618. The main body 809A rotates integrally with the transmission shaft 618. In other words, the main body 809A receives torque from the driving device 615 and rotates around the rotation center axis 615V. The plurality of teeth 809B protrude from the outer peripheral surface of the main body 809A. The plurality of teeth 809B are arranged at equal intervals in the circumferential direction around the rotation center axis 615V. In addition, Figure 23 In the figure, the pinion 809 is merely shown schematically. Figure 23 The number and shape of the teeth 809B shown do not necessarily correspond to the actual number and shape. This also applies to the gear wall 810 described later.

[0441] <Gear Wall>

[0442] like Figure 22 As shown, the boom swing mechanism 800A has a gear wall 810. The gear wall 810 is located on the lower side relative to the lower wall 612 of the swing bracket 610. The gear wall 810 is located on the front side relative to the pinion 809. Figure 23 As shown, the gear wall 810 includes a main body 811 and a plurality of teeth 812. The main body 811 is plate-shaped. The largest surface of the outer surface of the main body 811 is called the main surface 811A. Figure 22 As shown, the two main surfaces 811A face upward and downward. The upper side of the two main surfaces 811A is fixed to the lower surface 612D of the lower wall 612. Figure 23As shown, the main surface 811A is semicircular. The center axis of the semicircular arc in the main surface 811A is roughly consistent with the rotation center axis 610V. The portion of the main body 811 corresponding to the thickness is composed of an arc surface 811B and a flat surface 811C. The arc surface 811B is along the arc portion of the main surface 811A. That is, the arc surface 811B is an arc centered on the rotation center axis 610V. The arc surface 811B extends approximately 180 degrees in the circumferential direction centered on the rotation center axis 610V. The diameter of the arc in the arc surface 811B is larger than the outer diameter of the main body 809A of the pinion 809. The flat surface 811C is along the straight line portion in the semicircle of the main surface 811A. The flat surface 811C connects the two ends of the arc in the arc surface 811B. When looking down in the direction along the rotation center axis 610V, the flat surface 811C extends in a straight line. As shown Figure 22 As shown, when gear wall 810 is fixed to lower wall 612, flat surface 811C forms the frontmost portion of gear wall 810. In the X-direction, flat surface 811C is located approximately coaxially with rotational axis 610V. Furthermore, arcuate surface 811B extends rearward from flat surface 811C. Arcuate surface 811B faces pinion gear 809.

[0443] A plurality of teeth 812 protrude from arcuate surface 811B. Teeth 812 are arranged at equal intervals in the circumferential direction centered about rotational axis 610V. Some of teeth 812 mesh with some of teeth 809B on pinion 809. A gap, called backlash, exists between teeth 812 on gear wall 810 and teeth 809B on pinion 809.

[0444] <Function of the Sixth Embodiment>

[0445] In the boom swing mechanism 800A, when the output shaft 616B of the electric motor 616 rotates, the pinion 809 rotates. The rotation of the pinion 809 is then transmitted to the gear wall 810 through the meshing of the teeth of the pinion 809 and the gear wall 810. This causes the gear wall 810 to rotate about the rotational axis 610V. This also causes the swing bracket 610 and the boom 530, which are integral with the gear wall 810, to rotate. The boom 530 rotates leftward or rightward depending on the rotational direction of the output shaft 616B of the electric motor 616.

[0446] <Effects of the Sixth Embodiment>

[0447] (6-1) As described in the operation of the above embodiment, in the excavator 800 of this embodiment, the boom 530 can be swung left and right using the electric motor 616 as a driving source.

[0448] The diameter of the arc surface 811B in the gear wall 810 is larger than the outer diameter of the main body 809A of the pinion 809. As a result of such a size relationship, the gear wall 810 amplifies the torque of the pinion 809 and transmits it to the swing bracket 610. That is, in the structure of the present embodiment, the gear wall 810 and the pinion 809 constitute a reduction mechanism. If the reduction mechanism can be constituted by the gear wall 810 and the pinion 809, it is allowed to suppress the torque amplification capability in the reducer 617 of the drive device 615. If the torque amplification capability can be suppressed, the enlargement of the structural components of the reducer 617 can be avoided. That is, in the structure of the present embodiment, the enlargement of the reducer 617 and the drive device 615 as a whole can be suppressed.

[0449] In addition, as described in the first embodiment, a load can be input from the outside to the boom 530 due to the collision between the bucket 550 and the excavation object. This load is called a collision load. In the case of adopting the boom swing mechanism 800A of this embodiment, the collision load can be transmitted from the swing bracket 610 to the gear wall 810. However, this collision load is released in the gap between the gear wall 810 and the pinion 809 and is hardly transmitted to the pinion 809 and the drive unit 615. Therefore, in the structure of this embodiment, it is possible to suppress the collision load acting on the gear wall 810 from reaching the reducer 617 and the electric motor 616. Therefore, in the structure of this embodiment, as in the other embodiments, there is no need to provide a structure for bearing the collision load in the reducer 617 and the electric motor 616. As in the above embodiment, this also helps to suppress the increase in size of the drive unit 615.

[0450] (6-2) In this embodiment, the angle of the arc on the arc surface 811B of the gear wall 810 is approximately 180 degrees. In other words, the gear wall 810 is semicircular. By making the gear wall 810 semicircular rather than perfectly circular, the size of the gear wall 810 can be reduced compared to a case where the gear wall 810 is perfectly circular. In this case, the space dedicated to the gear wall 810 can be reduced. Therefore, in the structure of this embodiment, the layout changes of other components caused by the installation of the gear wall 810 are less likely to be required.

[0451] <Modification of Sixth Embodiment>

[0452] The sixth embodiment can be modified and implemented as follows: The first to sixth embodiments and the following modified examples can be combined and implemented within a range that does not technically conflict with each other.

[0453] The structure of the gear wall 810 is not limited to the example in the above-described embodiment. The gear wall 810 only needs to have an arc-shaped arc surface 811B centered on the rotation center axis 610V and a plurality of teeth 812 protruding from the arc surface 811B. Furthermore, the diameter of the arc of the arc surface 811B only needs to be greater than the outer diameter of the pinion 809. For example, in the gear wall 810, the angular range of the arc of the arc surface 811B can be modified from the example in the above-described embodiment. If a structure is adopted in which the angular range of the arc of the arc surface 811B is greater than 165 degrees and less than 195 degrees, and the two ends of the arc of the arc surface 811B are connected by a straight flat surface 811C, as described in (6-2) above, this is effective in reducing the size of the gear wall 810. Furthermore, the angular range of the arc of the arc surface 811B can be appropriately changed. Furthermore, it is not necessary for the two ends of the arc in the arc surface 811B to be connected by a straight flat surface 811C. As long as the swing bracket 610 can rotate due to the meshing of the gear wall 810 and the pinion 809, the central axis of the arc of the arc surface 811B of the gear wall 810 may not coincide with the rotation center axis 610V. In this case, the central axis of the arc of the arc surface 811B only needs to be parallel to the rotation center axis 615V of the drive device 615.

[0454] The arrangement of the gear wall 810 is not limited to the example in the above embodiment. The gear wall 810 can be arranged so that the teeth 812 of the gear wall 810 face the teeth 809B of the pinion 809. Furthermore, the gear wall 810 can be arranged so that it can rotate about the rotational axis 610V. For example, the pin 620 can be extended below the lower wall 612 of the swing bracket 610, and the gear wall 810 can be fixed at a position separated from the lower wall 612 in the Z direction.

[0455] The structure, configuration, and connection method of the swing bracket 610 to the vehicle body are not limited to the above-mentioned embodiment. The swing bracket 610 can be fixed to the boom 530 and connected to the vehicle body in a manner that allows it to rotate around the rotation center axis 610V. In addition, the structure of the vehicle body for supporting the swing bracket 610 is not limited to the above-mentioned embodiment. For example, the following embodiment can be used. Figure 24 In addition, the vehicle body is not limited to the storage portion 607, as long as it is somewhere on the upper body 606. Moreover, as described in the following modified examples, the vehicle body is not limited to the upper body 606.

[0456] In excavator 800, the slewing bearing 603 is not essential. Specifically, depending on the structure of excavator 800, the upper body 606 may not be able to swivel relative to the lower body 602, and the upper body 606 and lower body 602 may be integrally formed. In this case, the upper body 606 and lower body 602 constitute the vehicle body. That is, the vehicle body is not limited to the example in the above embodiment.

[0457] The location where the boom 530 is fixed to the swing bracket 610 is not limited to the example in the above embodiment. The boom 530 may be fixed to any location on the swing bracket 610.

[0458] The arrangement of the pinion 809 is not limited to the example in the above embodiment. The arrangement of the pinion 809 can be varied depending on the structure and arrangement of the drive device 615. The pinion 809 only needs to be arranged so as to receive torque from the drive device 615 and rotate about the rotational axis of the drive device 615.

[0459] The structure of the drive device 615 is not limited to the example of the above embodiment. The drive device 615 only needs to include the electric motor 616 and output torque centered on the rotation center axis. For example, the reducer 617 and the transmission shaft 618 can be omitted from the drive device 615. In addition, the pinion 809 can be directly mounted on the output shaft 616B of the electric motor 616. In addition, the drive device 615 can be configured so that the center axis of the output shaft 616B of the electric motor 616 and the rotation center axis of the torque output by the drive device 615 to the outside of itself are arranged at different positions. If a mechanism for changing the rotation direction of the electric motor 616 is provided in the drive device 615, such a structure is also feasible. The rotation center axis of the torque output by the drive device 615 only needs to extend above and below the vehicle body as a whole. For example, it may be inclined within a range of about 15 degrees relative to the Z direction.

[0460] The configuration of the drive unit 615 is not limited to the example of the above embodiment. The drive unit 615 only needs to be fixed somewhere in the housing 607. Furthermore, the drive unit 615 is not limited to the housing 607, and can be fixed somewhere in the vehicle body. In addition, as long as the swing bracket 610 can be rotated by the engagement of the pinion 809 with the gear wall 810 using the drive unit 615 as a power source, the fixing objects of the drive unit 615 and the gear wall 810 can also be replaced between the vehicle body and the swing bracket 610. Figure 24 An example of a case where such a change is applied will be described. Figure 24 In, with Figure 22 and Figure 23 Parts that perform the same or substantially the same function are marked with Figure 22 and Figure 23In addition, Figure 22 Likewise, in Figure 24 A portion of a component is shown through a cross section.

[0461] Below, about Figure 24 The excavator 800 shown is Figure 23 The excavator 800 will be described primarily by focusing on the different parts. In the excavator 800, the upper body 606 includes a first support wall 805 and a second support wall 806 in place of the support wall 609. The first support wall 805 and the second support wall 806 protrude forward from the front surface 607F of the accommodating portion 607. The first support wall 805 and the second support wall 806 are fixed to the front surface 607F of the accommodating portion 607. In the Y direction, the first support wall 805 and the second support wall 806 span the center of the accommodating portion 607. The first support wall 805 and the second support wall 806 are plate-shaped with thickness at the top and bottom. For example, the first support wall 805 and the second support wall 806 are rectangular. The outer dimensions of the first support wall 805 and the second support wall 806 are substantially identical. The first support wall 805 is located above the second support wall 806. The lower surface of the first support wall portion 805 and the upper surface of the second support wall portion 806 face each other.

[0462] The upper body 606 also includes a third support wall 807. The third support wall 807 is located above the first support wall 805. The third support wall 807 protrudes forward from the front surface 607F of the accommodating portion 607. The third support wall 807 is fixed to the front surface 607F of the accommodating portion 607. For example, the third support wall 807 is in the shape of a rectangular parallelepiped that is long in the Y direction. In the Y direction, the third support wall 807 spans the center of the accommodating portion 607. The front end of the third support wall 807 is located further rearward than the front ends of the first support wall 805 and the second support wall 806.

[0463] The excavator 800 has a boom swing mechanism 800B as an electric actuator. The boom swing mechanism 800B has a swing bracket 610 and a pin 620. The structure and connection of the swing bracket 610 and the pin 620 Figure 22The structures described above are essentially the same. However, the outer dimensions of the upper wall 611 and lower wall 612 of the swing bracket 610 differ. Furthermore, the lower wall 612 of the swing bracket 610 is located between the first support wall 805 and the second support wall 806 of the upper body 606. The through-hole 612A of the lower wall 612 is positioned so that the front end of the third support wall 807 is located on its central axis. Furthermore, the diameter of the through-hole 612A of the lower wall 612 is larger than the diameter of the pin 620. Furthermore, in the boom swing mechanism 800B, the pin 620 passes through the through-hole 612A and through both the first support wall 805 and the second support wall 806. The pin 620 is fixed to the first support wall 805 and the second support wall 806. On the other hand, to balance the diameter relationship between the through-hole 612A and the pin 620, a gap exists between the through-hole 612A and the pin 620. Therefore, the pin 620 and the lower wall 612 are in a state where they can rotate relative to each other. In other words, the lower wall 612 can rotate with the pin 620 as the central axis. In addition, the central axis of the pin 620 constitutes the rotation center axis 610V which becomes the rotation center of the lower wall 612 and the swing bracket 610. The rotation center axis 610V extends in the approximate Z direction. Figure 24 In the figure, the gap between the pin 620 and the through-hole 612A in the lower wall 612 is exaggerated. Furthermore, in the boom swing mechanism 800B, the center axis of the through-hole 611A in the upper wall 611 is offset from the center axis of the through-hole 612A in the lower wall 612. Specifically, the center axis of the through-hole 611A in the upper wall 611 is located closer to the connecting wall 613 than the center axis of the through-hole 612A in the lower wall 612.

[0464] The boom swing mechanism 800B has a drive unit 615. Most of the drive unit 615 is located on the upper side relative to the upper wall 611 of the swing bracket 610. Figure 22The structure is the same as that already described. Specifically, the drive unit 615 includes an electric motor 616, a speed reducer 617, and a transmission shaft 618. The electric motor 616, speed reducer 617, and transmission shaft 618 are arranged in this order from top to bottom. The central axis of the output shaft 616B of the electric motor 616 is approximately aligned with the central axis of the transmission shaft 618. The central axis of the transmission shaft 618 constitutes the rotational axis 615V of the drive unit 615. The rotational axis 615V of the drive unit 615 is approximately parallel to the rotational axis 610V. The drive unit 615 is fixed to the upper wall 611 of the swing bracket 610. Specifically, the speed reducer 617 of the drive unit 615 is fixed to the upper surface of the upper wall 611. Furthermore, the transmission shaft 618 extends through a through hole 611A in the upper wall 611. The lower portion of the transmission shaft 618 protrudes downward from the lower surface of the upper wall 611. As described above, the central axis of the through hole 611A in the upper wall 611 is offset from the central axis of the through hole 612A in the lower wall 612. To accommodate this, the rotational central axis 615V of the driving device 615 is offset from the rotational central axis 610V.

[0465] The boom swing mechanism 800B has a pinion 809. The structure and combination of the pinion 809 Figure 22 The pinion gear 809 is the same as described above. Specifically, the pinion gear 809 has a cylindrical main body 809A and a plurality of teeth 809B protruding from the outer circumference of the main body 809A. The pinion gear 809 is located downward relative to the upper wall 611 of the swing bracket 610. The portion of the transmission shaft 618 that protrudes from the lower surface of the upper wall 611 is positioned within the central hole of the main body 809A of the pinion gear 809. The main body 809A of the pinion gear 809 is fixed to the transmission shaft 618. In other words, the pinion gear 809 rotates integrally with the transmission shaft 618.

[0466] The boom swing mechanism 800B has a gear wall 810. The structure and combination of the gear wall 810 Figure 22 and Figure 23 The structure is the same as that described above. Figure 23 As shown, the gear wall 810 has an arc surface 811B, a flat surface 811C connecting the two ends of the arc of the arc surface 811B, and a plurality of teeth 812 protruding from the arc surface 811B. Figure 24As shown, the gear wall 810 is located between the pinion 809 and the third support wall portion 807 in the upper body 606. The gear wall 810 is fixed to the front end of the third support wall portion 807. Specifically, the flat surface 811C in the gear wall 810 is fixed to the front end of the third support wall portion 807. Furthermore, the arcuate surface 811B in the gear wall 810 protrudes forward relative to the flat surface 811C. The central axis of the arc in the arcuate surface 811B is approximately aligned with the rotational center axis 610V. The arcuate surface 811B faces the pinion 809. Furthermore, a portion of the plurality of teeth 812 protruding from the arcuate surface 811B meshes with a portion of the plurality of teeth 809B in the pinion 809. A gap, called a backlash, exists between the teeth 812 of the gear wall 810 and the teeth 809B of the pinion 809. Alternatively, the gear wall 810 may be directly fixed to the front surface 607F of the housing 607 without passing through the third support wall portion 807. In this case, for example, the shape of the gear wall 810 may be appropriately changed by changing the angle range of the arc of the arc surface 811B or by changing the shape of the portion connecting the two ends of the arc of the arc surface 811B so that the central axis of the arc surface 811B substantially coincides with the rotational center axis 610V.

[0467] The operation of the boom swing mechanism 800B will be described. When the output shaft 616B of the electric motor 616 rotates, the pinion 809 rotates about the rotation axis 615V of the drive unit 615. Furthermore, the pinion 809, meshing with the teeth 812 of the gear wall 810, orbits around the circular surface 811B of the gear wall 810 about the rotation axis 610V. As this orbital movement occurs, the swing bracket 610 rotates about the rotation axis 610V, causing the boom 530 to rotate.

[0468] In boom swing mechanism 800B, gear wall 810 and pinion 809 form a speed reduction mechanism by utilizing the size relationship between the diameter of the arc surface 811B of gear wall 810 and the outer diameter of pinion 809. Therefore, boom swing mechanism 800B also achieves the same effect as described in (6-1) above. Furthermore, in boom swing mechanism 800B, since gear wall 810 is semicircular, the same effect as described in (6-2) above can be achieved.

[0469] The construction machine to which the boom swing mechanisms 800A and 800B, which are electric actuators, are applied is not limited to the excavator 800 .

[0470] In the above embodiment, various mechanisms can be used to fix the two members. Examples of the mechanism to fix the two members include bolt fastening, welding, integral molding, spline connection, and the like.

[0471] In the above embodiment, a portion composed of multiple objects may be integrated into the multiple objects, and conversely, a portion composed of one object may be divided into multiple objects. Regardless of integration or not, it is sufficient as long as the purpose of the present invention can be achieved.

[0472] <Seventh embodiment>

[0473] Below, use Figure 25 A seventh embodiment of a construction machine and an electric actuator for a construction machine will be described. It should be noted that the drawings sometimes enlarge the structural components to facilitate understanding. In addition, the dimensional ratios of the structural components may sometimes differ from the actual dimensional ratios or the dimensional ratios in other drawings. Figure 25 In, with Figures 1 to 24 Parts that perform the same or substantially the same function are marked with Figures 1 to 24 In the following description, the description of the parts that overlap with those of the first to sixth embodiments may be appropriately omitted or simplified.

[0474] Overall Structure

[0475] like Figure 25 As shown, an excavator 830 as a construction machine has a lower body 602, an upper body 606 as a vehicle body, a pair of travel devices 510, and a slewing bearing 603. The structures of the lower body 602, the pair of travel devices 510, and the slewing bearing 603 are the same as those in the second embodiment. Therefore, their description is omitted. The upper body 606 will be described later. With respect to the lower body 602, the upper body 606 is located on the side opposite to the ground. In addition, in this embodiment, up, down, left, right, front, and back are defined in the same way as in the second embodiment. For the convenience of explanation, Figure 25 A portion of the components of the excavator 830 is shown in cross section.

[0476] The upper body 606 has a storage portion 607, a first support wall portion 831, a second support wall portion 832, and a boarding portion. Figure 25 The structure of the storage portion 607 and the boarding portion is the same as that of the second embodiment.

[0477] The first support wall 831 protrudes forward from the front surface 607F of the accommodating portion 607. The first support wall 831 is fixed to the front surface 607F of the accommodating portion 607. The first support wall 831 is, for example, in the shape of a quadrilateral plate. The main surface of the first support wall 831 faces upward and downward. The main surface is the largest surface of the plate-shaped object. The first support wall 831 spans the center of the accommodating portion 607 in the Y direction.

[0478] The second support wall 832 is located above the first support wall 831. The second support wall 832 is located apart from the first support wall 831 in the Z direction. The second support wall 832 protrudes forward from the front surface 607F of the accommodating portion 607. The second support wall 832 is fixed to the front surface 607F of the accommodating portion 607. The second support wall 832 has, for example, a rectangular plate shape. The main surface of the second support wall 832 faces upward and downward. The longitudinal and transverse dimensions of the main surface of the second support wall 832 are smaller than those of the main surface of the first support wall 831. As a result of this size relationship, the front end of the second support wall 832 is located further rearward than the front end of the first support wall 831. The second support wall 832 has a through-hole 832A. The through-hole 832A extends vertically through the second support wall 832. The central axis of the through-hole 832A extends generally in the Z direction.

[0479] Excavator 830, as an excavation machine, includes a boom 530, an arm 540, and a bucket 550. Boom 530, arm 540, and bucket 550 are positioned forward relative to the housing 607 of the upper body 606. The structures of boom 530, arm 540, and bucket 550 are identical to those of the second embodiment. Therefore, their description will be omitted.

[0480] <Boom swing mechanism>

[0481] The excavator 830 includes a boom swing mechanism 830A. The boom swing mechanism 830A is a mechanism for swinging the boom 530 left and right relative to the upper body 606. The boom swing mechanism 830A constitutes an electric actuator.

[0482] The boom swing mechanism 830A includes a bearing 840. The bearing 840 includes an inner ring 841, rolling elements 842, and an outer ring 843. The bearing 840 is located on the upper side relative to the first support wall portion 831 in the upper body 606.

[0483] The inner ring 841 is annular. The central axis of the inner ring 841 extends generally in the Z direction. The lower end surface of the inner ring 841, which is located on one side along the central axis, faces the upper surface of the first support wall 831. Furthermore, the lower end surface of the inner ring 841 is fixed to the upper surface of the first support wall 831. In other words, the inner ring 841 is attached to the first support wall 831, which is part of the vehicle body.

[0484] Outer ring 843 includes a main body 843A, an upper wall 843B, and a plurality of teeth 843C. Main body 843A is annular. The central axis of main body 843A is approximately aligned with the central axis of inner ring 841. In other words, main body 843A and inner ring 841 are coaxially arranged. Hereinafter, the central axis of main body 843A will be referred to as rotational axis 840V. The dimension of main body 843A along rotational axis 840V is smaller than the dimension of inner ring 841 along rotational axis 840V. The inner diameter of main body 843A is larger than the outer diameter of inner ring 841. Furthermore, in a radial direction (hereinafter referred to as the radial direction) centered on rotational axis 840V, main body 843A is located outside inner ring 841. Main body 843A surrounds inner ring 841 from the radial outside.

[0485] Upper wall 843B is located upward relative to main body 843A. Upper wall 843B is disc-shaped. The center of the circle of upper wall 843B is located on the rotation center axis 840V. The diameter of upper wall 843B is approximately the same as the outer diameter o...

Claims

1. A construction machine, wherein: have: body; a drive device including an electric motor configured to output a torque centered on a rotational axis extending vertically along the vehicle body; a swing bracket connected to the vehicle body and configured to receive torque from the drive device and rotate about a rotation center axis parallel to the rotation center axis or about the rotation center axis; and The movable arm is fixed to the swing bracket.

2. An electric actuator for a construction machine, wherein: have: a drive device including an electric motor and configured to output torque centered on a rotational central axis; and The swing bracket is fixed to the boom and is configured to receive torque from the driving device and rotate around a rotation center axis parallel to the rotation center axis or the rotation center axis.

3. The electric actuator for construction machinery according to claim 2, wherein: The driving device comprises: a transmission shaft disposed in a first through hole provided in a vehicle body of the construction machine and rotatable about the rotation center axis; The electric motor is mounted on the vehicle body, and its output shaft is connected to the transmission shaft; a speed reducer mounted in the vehicle body at a position opposite to the electric motor across the first through hole, having an input shaft connected to the transmission shaft and configured to amplify and output torque output by the output shaft of the electric motor; as well as An output member is connected to the swing bracket and is configured to receive torque from the speed reducer and rotate around the rotation center axis. The swing bracket is configured to receive torque from the output member and rotate about the rotation center axis.

4. The electric actuator for construction machinery according to claim 3, wherein: It further comprises: a cylindrical pin in which the transmission shaft is arranged, and arranged in the first through hole together with the transmission shaft. The swing bracket is in contact with the pin.

5. The electric actuator for construction machinery according to claim 3, wherein: The swing bracket has a facing wall, and the facing wall has a third through hole at a position facing the second through hole provided in the output member. The electric actuator further includes a connecting member connecting the output member and the facing wall. The connecting member has: a base portion disposed in the second through hole and the third through hole; and The cylindrical buffer portion has the base portion disposed therein and is disposed within the second through hole and the third through hole together with the base portion, and has an elastic modulus smaller than that of the base portion.

6. The electric actuator for construction machinery according to claim 3, wherein: The swing bracket has a facing wall facing the output member, The electric actuator further includes a connecting member connecting the opposing wall and the output member. There is a gap between the facing walls and the output member.

7. The electric actuator for construction machinery according to claim 2, wherein: The driving device is installed on the body of the construction machinery. The swing bracket is connected to the vehicle body in a manner rotatable about the rotation center axis. The electric actuator also has: a driving member configured to receive torque from the driving device and rotate about the rotation center axis; a transmitted member mounted on the swing bracket and configured to rotate about the rotation center axis; and The transmission mechanism is configured to rotate the driving member and the transmitted member in conjunction with each other.

8. The electric actuator for construction machinery according to claim 7, wherein: The driving member is a driving sprocket, which is annular with the rotation center axis as the center and has a plurality of teeth on the outer peripheral surface. The transmitted member is a driven sprocket, which is annular with the rotation center axis as the center and has a plurality of teeth on the outer peripheral surface. The transmission mechanism is a chain wound around the driving sprocket and the driven sprocket.

9. The electric actuator for construction machinery according to claim 7, wherein: The driving member is an annular driving pulley, centered on the rotation center axis. The transmitted member is an annular driven pulley, centered on the rotation center axis. The transmission mechanism is a belt wound around the driving pulley and the driven pulley.

10. The electric actuator for construction machinery according to claim 8 or 9, wherein: The outer diameter of the driving member is smaller than the outer diameter of the transmitted member.

11. The electric actuator for construction machinery according to claim 7, wherein: The construction machine has a lower body and an upper body serving as the vehicle body. The upper body is located on the side opposite to the ground relative to the lower body of the construction machine and is supported by a slewing bearing so as to be rotatable relative to the lower body. When the rotation center axis is set as the first rotation center axis, the direction of the first rotation center axis when viewed from the second rotation center axis as the center axis of rotation of the upper body is set as the first direction, and the part of the slewing bearing closest to the first rotation center axis in the first direction is set as the specific part, At least a portion of the driving member is located on an imaginary line segment connecting the specific portion and the first rotation center axis.

12. The electric actuator for construction machinery according to claim 7, wherein: The construction machine has a lower body and an upper body serving as the vehicle body. The upper body is located on the side opposite to the ground relative to the lower body of the construction machine and is supported by a slewing bearing so as to be rotatable relative to the lower body. The electric actuator further includes one or more intermediate members, each of which is mounted on the vehicle body and rotates around a central axis parallel to the rotational central axis. The transmission mechanism is configured to rotate the one or more intermediate members, the driving member, and the transmitted member in a coordinated manner. When the rotation center axis is set as the first rotation center axis, the direction in which the first rotation center axis is viewed from the second rotation center axis as the rotation center axis of the upper body is set as the first direction, and the direction opposite to the first direction is set as the second direction, When viewed from the driving member, the one or more intermediate members are located on the first direction side. The driving member and the driving device are located on the second direction side when viewed from the second rotation center axis.

13. The electric actuator for construction machinery according to claim 2, wherein: The driving device is installed on the body of the construction machinery. The swing bracket is fixed to the output member of the driving device, and is configured to receive torque from the driving device and rotate about the rotation center axis.

14. The electric actuator for a construction machine according to claim 13, wherein: The drive device includes a speed reducer configured to amplify and output the torque output by the electric motor. The speed reducer is configured to output torque output by the electric motor centered on the rotation center axis to the swing bracket coaxially with the electric motor.

15. The electric actuator for a construction machine according to claim 13, wherein: The driving device is located on the lower side relative to the swing bracket. The swing bracket is fixed to the output member of the driving device by bolts.

16. The electric actuator for a construction machine according to claim 2, wherein: The swing bracket and the driving device are arranged in a direction along the rotation center axis, The electric actuator also has: a transmission member configured to be located between the driving device and the swing bracket and to transmit the torque of the driving device to the swing bracket; An annular bearing is mounted on a vehicle body of the construction machine, the transmission member passes through the bearing, and the transmission member is rotatably supported. a holding member located on the opposite side of the swing bracket across the bearing in the direction along the rotation center axis, the driving device penetrating the holding member; and a buffer member connecting the holding member and the vehicle body, having an elastic modulus smaller than that of the holding member, The swing bracket is configured to receive the torque of the driving device via the transmission member and rotate about the rotation center axis.

17. The electric actuator for a construction machine according to claim 16, wherein: The bearing is a first bearing of a plurality of bearings, The plurality of bearings are arranged in a direction along the rotation center axis.

18. The electric actuator for a construction machine according to claim 2, wherein: The driving device is in a cylindrical shape with the rotation center axis as the center. The swing bracket is arranged with the driving device in a direction along the rotation center axis, and is fixed to the output member of the driving device, receives torque from the driving device, and rotates around the rotation center axis. The electric actuator also has: a flange wall located on a side opposite to the swing bracket relative to the drive device in a direction along the rotation center axis, supporting the drive device and being fixed to a body of the construction machine; a retaining member located between the swing bracket and the flange wall, the driving device passing through the retaining member; a buffer member connecting the holding member and the vehicle body and having a smaller elastic modulus than the holding member; and A pin passes through the driving device and is fixed to the flange wall.

19. The electric actuator for a construction machine according to claim 2, wherein: The swing bracket is connected to the vehicle body of the construction machine in a manner rotatable about the rotation center axis. The electric actuator also has: a pinion gear configured to receive torque from the driving device and rotate about the rotation center axis; and The gear wall is arranged at a position facing the pinion, The gear wall has: an arc-shaped arc surface centered on a central axis parallel to the rotational central axis; and A plurality of teeth protruding from the arc surface and meshing with the teeth of the pinion, The diameter of the arc of the arc surface is larger than the outer diameter of the pinion, One of the gear wall and the driving device is fixed to the swing bracket, and the other is fixed to the vehicle body.

20. The electric actuator for construction machinery according to claim 19, wherein: The arc surface extends in a range of 165 degrees or more and 195 degrees or less in a circumferential direction centered on a central axis parallel to the rotational central axis. On the gear wall, both ends of the arc in the arc surface are connected by a flat surface extending linearly.

21. The electric actuator for a construction machine according to claim 2, wherein: Also features: An annular inner ring is mounted on the body of the construction machine and is centered on the central axis of rotation; an annular outer ring, configured to be coaxially arranged with the inner ring, having a plurality of teeth on an outer peripheral surface, and fixed to the swing bracket, rotating together with the swing bracket about the rotation center axis; a rolling element, configured to be located between the inner ring and the outer ring and to guide the inner ring and the outer ring to rotate relative to each other; and The pinion gear has teeth on its outer peripheral surface that mesh with the teeth of the outer ring and is arranged at a position facing the outer peripheral surface of the outer ring. It receives the torque output by the drive device and rotates around the rotation center axis.

22. A construction machine, wherein: have: body; a cylindrical first member; a second member, inserted into the interior of the first member from an end of the first member on one side along the central axis thereof and capable of reciprocating along the central axis of the first member; an electric motor configured to drive the second member to reciprocate relative to the first member; a swing bracket connected to the vehicle body so as to be rotatable about a rotation center axis extending vertically along the vehicle body; and A movable arm, fixed to the swing bracket, The first member is connected to one of the vehicle body and the swing bracket in a state rotatable about a central axis parallel to the rotational central axis. The second member is coupled to the other of the vehicle body and the swing bracket in a state rotatable about a central axis parallel to the rotation central axis.

23. An electric actuator for a construction machine, wherein: have: a cylindrical first member; a second member, inserted into the interior of the first member from an end of the first member on one side along the central axis thereof and capable of reciprocating along the central axis of the first member; an electric motor configured to drive the second member to reciprocate relative to the first member; as well as The swing bracket is connected to the vehicle body of the construction machine in a manner that allows it to rotate around the rotation center axis, and is fixed to the boom. The first member is connected to one of the vehicle body and the swing bracket in a state rotatable about a central axis parallel to the rotational central axis. The second member is coupled to the other of the vehicle body and the swing bracket in a state rotatable about a central axis parallel to the rotation central axis.

24. The electric actuator for a construction machine according to claim 23, wherein: The second member is in the shape of a tube extending along the central axis of the first member and has an internal thread formed on its inner circumference. The electric actuator also has: a screw shaft inserted into the second member from an end of the second member opposite to the one side, having an external thread formed on an outer peripheral surface thereof and rotating about a central axis of the second member in accordance with rotation of the electric motor; and A ball is located between the screw shaft and the second member.

25. The electric actuator for a construction machine according to claim 24, wherein: The rotation center axis of the electric motor extends parallel to the center axis of the second member at a position different from the center axis of the second member. The electric actuator further includes a transmission mechanism configured to transmit the rotation of the electric motor to the screw shaft.

26. The electric actuator for a construction machine according to claim 23, wherein: The first member defines a fluid chamber for supplying or discharging fluid. The second member has: a piston dividing the fluid chamber into two parts in a direction along the central axis of the first member, a rod extending from said piston toward said one side, The electric actuator further includes a fluid circuit that supplies or discharges fluid to or from each of the two-part fluid chamber in response to driving of a pump driven by the electric motor.

27. The electric actuator for a construction machine according to claim 23, wherein: The second member is in a columnar shape extending in a direction along the central axis of the first member, and has a plurality of rack teeth arranged in a direction along the central axis of the first member on an outer surface. The electric actuator further includes a pinion gear rotatable about an axis intersecting the central axis of the second member and having teeth meshing with the rack teeth on an outer peripheral surface. The pinion gear is driven to rotate by the electric motor.

28. The electric actuator for a construction machine according to claim 27, wherein: The construction machine has a lower body and an upper body serving as the vehicle body. The upper body is located on the side opposite to the ground relative to the lower body of the construction machine and is supported by a slewing bearing so as to be rotatable relative to the lower body. The rotation center axis of the electric motor is consistent with the center axis of the pinion gear, When the rotation center axis is set as a first rotation center axis, an imaginary line segment connecting the second rotation center axis as the center axis of rotation of the upper body and the first rotation center axis when viewed from above in the direction along the first rotation center axis is set as a first line segment, When an imaginary line segment connecting the end of the second member on the one side and the end of the first member on the side opposite to the side where the second member is inserted in the direction along the central axis of the first member is defined as a second line segment, A rotation center axis of the electric motor is located between the first line segment and the second line segment.

29. A construction machine, wherein: have: body; an electric motor mounted on the vehicle body and configured to output a torque centered on a rotational central axis; a swing bracket connected to the vehicle body so as to be rotatable about a rotation center axis intersecting the rotation center axis and extending vertically along the vehicle body; a conversion mechanism configured to convert the torque of the electric motor centered on the rotation center axis into a torque centered on the rotation center axis; a transmission member configured to transmit the torque converted by the conversion mechanism to the swing bracket; and The movable arm is fixed to the swing bracket.

30. An electric actuator for a construction machine, wherein: have: an electric motor configured to output torque centered about a rotational center axis; a swing bracket fixed to the boom and connected to the body of the construction machine so as to be rotatable about a rotation center axis extending in a direction intersecting the rotation center axis; a conversion mechanism configured to convert the torque of the electric motor centered on the rotation center axis into a torque centered on the rotation center axis; The transmission member is configured to transmit the torque converted by the conversion mechanism to the swing bracket.

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