Construction machinery

Abstract

To provide a drive transmission device and a construction machine capable of securing sufficient mechanical strength while miniaturizing the same.SOLUTION: A drive transmission device 1 includes: one differential device 2 to which rotation of a motor 120 is transmitted; operation output shafts 76a, 76b connected to the differential device 2; and two speed reduction portions 3A, 3B having carriers 14 for changing rotation speeds of the operation output shafts 76a, 76b and outputting the same. In two speed reduction portions 3A, 3B, the operation output shafts 76a, 76b and the carriers 14 are disposed along the same second rotation axis C2 direction and disposed in opposition to each other along the second rotation axis C2.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0003]

[0001] The present invention relates to a drive transmission device and a construction machine.

Background Art

[0002] For example, a construction machine such as a hydraulic excavator includes a traveling body that travels, and a revolving body that is rotatably provided on the traveling body. The revolving body includes an operation cab on which an operator rides. Further, the revolving body is provided with a working unit having one end rotatably (oscillatably) connected thereto. Examples of the working unit include a boom, an arm having one end rotatably connected to the other end of the boom on the side opposite to the revolving body, and a bucket having one end rotatably connected to the other end of the arm on the side opposite to the boom.

[0003] In many cases, a hydraulic actuator of a linear motion mechanism is provided as a drive transmission device at the connection portion between the revolving body and the boom, the connection portion between the boom and the arm, and the connection portion between the arm and the bucket. By driving the hydraulic actuator, the revolving body is caused to perform a turning motion with respect to the traveling body, or the boom, the arm, and the bucket are caused to perform a swinging motion. By the way, in recent years, electrification has been desired from the viewpoint of simplifying the structure of construction machines. For this reason, it has been proposed to use an electric actuator as a drive transmission device. For example, a technique using an electric cylinder of a linear motion mechanism incorporating a ball screw type speed change unit (speed reduction device) in place of a hydraulic actuator has been disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In construction machinery, the various connecting parts are prone to heavy loads due to their operating environment. Therefore, the transmission unit, in particular, requires sufficient mechanical strength to withstand these loads. This resulted in the transmission unit becoming larger, leading to the challenge of an overall larger drive transmission system.

[0006] The present invention provides a drive transmission device and construction machinery that can be miniaturized while ensuring sufficient mechanical strength. [Means for solving the problem]

[0007] A drive transmission device according to one aspect of the present invention comprises one transmission unit to which the rotation of a drive source that generates rotational force is transmitted, and two speed control units having an input shaft connected to the transmission unit and an output shaft that changes the speed of the rotation of the input shaft and outputs the result, wherein the input shaft and the output shaft of the two speed control units are provided along the same rotation axis direction and are arranged opposite to each other along the rotation axis direction.

[0008] This configuration allows for the space-saving placement of two gearboxes that receive rotation from a single transmission unit, thus enabling a smaller drive transmission system. The presence of two gearboxes also distributes the load between them, providing sufficient mechanical strength for the drive transmission system.

[0009] In the above configuration, the transmission unit may be positioned between the two gear shifting units.

[0010] In the above configuration, the transmission unit includes a differential having a ring gear to which the rotation of the drive source is transmitted, The input shaft may be connected to the drive shaft of the differential.

[0011] In the above configuration, an overload protection device may be provided that connects each of the input shafts of each of the gear shifting units and rotates each of the input shafts relative to each other when the torque difference between each of the input shafts exceeds a certain value.

[0012] In the above configuration, the gear shifting unit may be an eccentric oscillating type gear shifting unit that receives the rotation of the input shaft and rotates about another rotation axis parallel to the rotation axis direction of the input shaft, and transmits the rotation of the crankshaft at a reduced speed to the output shaft, thereby reducing the rotation of the output shaft relative to the input shaft.

[0013] In the above configuration, the device may have a plurality of crankshafts, an external tooth member having external teeth that oscillate around the rotation axis by the crankshafts, and a case having internal teeth that mesh with the external teeth, wherein the output shaft is a carrier that rotatably supports the crankshafts and is rotatably supported by the case via bearings, and rotates at a reduced speed relative to the case by the crankshafts.

[0014] Another aspect of the present invention relates to a drive transmission device comprising a differential having a ring gear on which the rotation of a motor is transmitted, and two speed control units arranged on either side of the differential, each having an input shaft connected to the drive shaft of the differential and an output shaft that changes the speed of the rotation of the input shaft and outputs the result, wherein the speed control units include at least one crankshaft that receives the rotation of the input shaft and rotates about another rotation axis parallel to the rotation axis direction, and are eccentric oscillating speed control units that reduce the rotation of the crankshaft and transmit it to the output shaft, thereby reducing the rotation of the output shaft relative to the input shaft.

[0015] This configuration allows the motor's rotation to be transmitted to two speed shifters via a single transmission unit. Furthermore, since the single transmission unit and two speed shifters can be installed in a space-saving manner, the drive transmission system can be miniaturized. By providing two speed shifters, the load can be distributed between them, thus providing sufficient mechanical strength for the drive transmission system. The gearbox is an eccentric oscillating type gearbox that includes at least one crankshaft, reduces the rotation of the crankshaft and transmits it to the output shaft, thereby reducing the rotation of the output shaft relative to the input shaft. This allows for a high simultaneous meshing ratio of the gears constituting the gearbox, improving the resistance of the drive transmission device to overloads and shock loads.

[0016] A construction machine according to another aspect of the present invention includes a first member having a drive source that generates a rotational force, and a second member rotatably connected to the first member about a rotation axis via a drive transmission device. The drive transmission device includes a transmission portion to which the rotational force of the drive source is transmitted, and two transmission portions that shift the rotation of the transmission portion and output it to the second member. The two transmission portions include an input shaft connected to the transmission portion and an output shaft connected to the second member. The input shaft and the output shaft are arranged along the rotation axis and are arranged opposite to each other in the rotation axis direction.

[0017] By configuring in this way, the connecting portion between the first member and the second member can be downsized. Even when a load is applied to the first member or the second member, this load is dispersed to the two transmission portions, so that sufficient mechanical strength of the drive transmission device can be ensured. In addition, the resistance to overload and impact load of the connecting portion between the first member and the second member can be improved.

Effect of the Invention

[0018] The above-described drive transmission device and construction machine can ensure sufficient mechanical strength while being downsized.

Brief Description of the Drawings

[0019] [Figure 1] Schematic configuration diagram of the excavator in the embodiment of the present invention as viewed from the side. [Figure 2] Schematic configuration diagram showing details of the connecting portion between the arm and the bucket in the first embodiment of the present invention. [Figure 3] Schematic configuration diagram of the differential device in the first embodiment of the present invention. [Figure 4] Schematic configuration diagram of the first reduction portion in the first embodiment of the present invention. [Figure 5] Schematic configuration diagram of a portion corresponding to the differential device in the drive transmission device in the second embodiment of the present invention.

Mode for Carrying Out the Invention

[0020] Next, embodiments of the present invention will be described based on the drawings.

[0021] <Excavator> FIG. 1 is a schematic configuration diagram of an excavator 100 according to an embodiment of the construction machine of the present invention as viewed from the side. In the following description, the front side facing an operator (not shown) who operates the excavator 100 is simply referred to as the front. The opposite side in the horizontal direction to the front is referred to as the rear. The vertical direction in the state where the excavator 100 is placed on the road surface is simply referred to as the vertical direction. The direction orthogonal to the front-rear direction and the vertical direction is referred to as the vehicle width direction. FIG. 1 shows the excavator 100 as viewed from the vehicle width direction.

[0022] As shown in FIG.  1, the excavator 100 includes a self-propelled traveling body 101, a revolving body 103 provided on the upper part of the traveling body 101 via a revolving mechanism 102 and revolving with respect to the traveling body 101, and a working part 104 provided on the revolving body 103. The traveling body 101 and the revolving mechanism 102 are driven by, for example, an electric motor with a speed reducer (not shown). The traveling body 101 includes, for example, two caterpillars 105 arranged in the vehicle width direction. However, the present invention is not limited to this, and wheels or the like may be used instead of the caterpillars 105.

[0023] The working part 104 includes a boom 108 and an arm 109 that are long in the front-rear direction, and a bucket 110. The boom 108, the arm 109, and the bucket 110 are each rotatably connected via a drive transmission device 1. Specifically, one end in the longitudinal direction of the boom 108 (in FIG. 1, one end in the longitudinal direction of the boom 108 and the drive transmission device 1 provided at this one end in the longitudinal direction are not shown) is rotatably connected to the revolving body 103 via the drive transmission device 1. One end 109a in the longitudinal direction of the arm 109 is rotatably connected to the other end 108a in the longitudinal direction of the boom 108 via the drive transmission device 1. The bucket 110 is rotatably connected to the other end 109b in the longitudinal direction of the arm 109 via the drive transmission device 1. The drive transmission devices 1 provided in each section are all identical in configuration. Therefore, in the following description, only the drive transmission device 1 that connects the bucket 110 to the other longitudinal end 109b of the arm 109 will be described, and the descriptions of the other drive transmission devices 1 will be omitted.

[0024] Figure 2 is a schematic diagram showing the details of the connection between the arm 109 and the bucket 110. In Figure 2, the arm 109 and the bucket 110 are shown with a dashed line for clarity. As shown in Figure 2, the arm 109 has a motor (an example of a motor, the drive source according to the claim) 120 built into it, and the rotational force of this motor 120 is transmitted to the bucket 110 via the drive transmission device 1. In other words, the arm 109 is an example of the first member according to the claim. The bucket 110 is an example of the second member according to the claim.

[0025] Motor 120 is a so-called electric motor that is driven by power supplied from an external power source (battery) provided on the rotating body 103, for example. Various types of motors that are driven by power supply can be used for motor 120, such as brushed motors and brushless motors. The motor 120 is positioned with its motor shaft 120a, which rotates around a first rotation axis C1, facing towards the bucket 110. The first rotation axis C1 of the motor shaft 120a coincides with the longitudinal direction of the arm 109.

[0026] [First Embodiment] <Drive transmission system> The drive transmission device 1 is positioned on the second rotation axis (an example of a rotation axis according to the claim) C2 of the bucket 110 relative to the arm 109. Mounting brackets 110a for the bucket 110 are positioned on both sides of the drive transmission device 1 on the second rotation axis C2. These mounting brackets 110a are fixed to the drive transmission device 1, causing the bucket 110 to rotate around the second rotation axis C2 relative to the arm 109.

[0027] The drive transmission device 1 comprises a differential gear 2 housed in a housing 4 fixed to the other longitudinal end 109b of the arm 109, and two reduction units 3A and 3B (first reduction unit 3A, second reduction unit 3B) arranged on either side of the differential gear 2 and connected to the differential gear 2, respectively. The rotation axes of the two reduction units 3A and 3B are parallel to the second rotation axis C2. In the following description, the direction parallel to the second rotation axis C2 may be referred to as the axial direction, the direction around the second rotation axis C2 may be referred to as the circumferential direction, and the direction perpendicular to the axial and circumferential directions may be referred to as the radial direction.

[0028] <Differential device> Figure 3 is a schematic diagram of the differential gear 2. The differential gear 2 is connected to the motor shaft 120a via a transmission shaft 121. The differential gear 2 is provided at the end of the transmission shaft 121 opposite to the motor 120 and includes a first bevel gear 71 that rotates about a first rotation axis C1, a second bevel gear (an example of a ring gear in the claims) 72 that meshes with the first bevel gear 71, a differential case 73 fixed to the second bevel gear 72, a pinion gear 74 that is rotatably supported in a manner that protrudes within the differential case 73, and a pair of side gears 75a, 75b (first side gear 75a, second side gear 75b) that mesh with the pinion gear 74.

[0029] The second bevel gear 72 rotates around the second rotation axis C2. An insertion hole 72a is formed in the radial center of the second bevel gear 72 for the first operating output shaft 76a, which will be described later, to pass through. The differential case 73 is fixed to the end face 72b of the second bevel gear 72 on the side of the first bevel gear 71. The differential case 73 is formed in a rectangular frame shape and has two sides 73a and 73b (first side 73a and second side 73b) that are facing each other in the axial direction, and two sides 73c and 73d (third side 73c and fourth side 73d) that are facing each other in a direction perpendicular to the planar direction of these sides 73a and 73b. Of the four sides 73a to 73d, the outer side of the first side 73a is fixed to the end face 72b on the first bevel gear 71 side.

[0030] Furthermore, pinion gears 74 are provided on the third side surface 73c and the fourth side surface 73d. The pinion gears 74 are rotatably supported on each side surface 73c and 73d with respect to a third rotation axis C3 perpendicular to the axial direction, and rotate together with the differential case 73 around the second rotation axis C2.

[0031] The pair of side gears 75a and 75b are positioned on either side of the pinion gear 74. Specifically, of the pair of side gears 75a and 75b, the first side gear 75a is positioned coaxially with the second rotation axis C2 inside the first side surface 73a of the differential case 73. Of the pair of side gears 75a and 75b, the second side gear 75b is positioned coaxially with the second rotation axis C2 inside the second side surface 73b of the differential case 73.

[0032] One end of the first operating output shaft 76a is provided on the end face 75c of the first side surface 73a of the first side gear 75a. The first operating output shaft 76a is arranged coaxially with the second rotation axis C2. The other end of the first operating output shaft 76a protrudes through the insertion hole 73e formed in the first side surface 73a and the insertion hole 72a of the second bevel gear 72. In other words, the first side gear 75a is rotatably supported on the first side surface 73a of the differential case 73. On the outer circumferential surface of the other end of the first operating output shaft 76a, a toothed portion 76c is formed that meshes with the first reduction gear 3A of the two reduction gears 3A, 3B.

[0033] The second side gear 75b has one end of the second operating output shaft 76b provided on its end face 75d on the second side surface 73b side. The second operating output shaft 76b is arranged coaxially with the second rotation axis C2. The other end of the second operating output shaft 76b protrudes through an insertion hole 73e formed in the second side surface 73b. In other words, the second side gear 75b is rotatably supported on the second side surface 73b of the differential case 73. The other end of the second operating output shaft 76b has teeth 76d formed on its outer circumferential surface that mesh with the second reduction gear 3B of the two reduction gears 3A, 3B. Thus, each operating output shaft 76a, 76b constitutes a part of each reduction unit 3A, 3B connected to the differential gear 2.

[0034] <Deceleration section> Figure 4 is a schematic diagram of the first deceleration unit 3A. The two reduction gears 3A and 3B have identical configurations and are arranged symmetrically around the third rotation axis C3. Therefore, the following explanation will primarily focus on the first reduction gear 3A, with the second reduction gear 3B being explained as needed. As shown in Figure 4, the first reduction unit 3A comprises a cylindrical case 11, a carrier 14 positioned radially inward of the case 11, and a reduction output unit 18 that rotates the carrier 14 at a rotational speed reduced by a constant ratio to the rotational speed of the first operating output shaft 76a.

[0035] <Case> An outer flange portion 11a is integrally molded on the outer circumferential surface of the case 11, protruding radially outward. The outer flange portion 11a has a square cross-section along the axial direction. The housing 4 is positioned on the end face 11b of the outer flange portion 11a on the differential gear 2 side (left side in Figure 4). The housing 4 is fastened and fixed to the outer flange portion 11a by bolts 5. Internal teeth 24 are provided on the inner circumferential surface of case 11. The internal teeth 24 are pin-shaped (cylindrical) teeth provided on the inner circumferential surface of case 11. Multiple internal teeth 24 are arranged at equal intervals in the circumferential direction.

[0036] <Career> The carrier 14 is rotatably supported in the case 11 by a pair of main bearings (an example of the bearings of the claim) 26, which are spaced apart in the axial direction. The main bearings 26 are, for example, angular contact ball bearings. The carrier 14 is positioned coaxially with the case 11 and the second rotation axis C2.

[0037] The carrier 14 comprises a base plate portion 32 positioned on the differential gear 2 side in the axial direction, an end plate portion 30 positioned on the opposite side of the base plate portion 32 from the differential gear 2, and three cylindrical column portions 33 integrally molded with the base plate portion 32 and protruding from the base plate portion 32 toward the end plate portion 30. The column portions 33 are arranged at equal intervals in the circumferential direction. An end plate portion 30 is positioned at the tip 33a of each column portion 33. A mounting bracket 110a for the bucket 110 is positioned on one side 30a of the end plate portion 30 opposite to the base portion 32. Both the end plate portion 30 and the mounting bracket 110a are fastened and fixed to the column portion 33 by bolts 34. In this state, a space with a constant width in the axial direction is formed between the base portion 32 and the end plate portion 30.

[0038] A pin 36 is provided slightly radially inward from the bolt 34 of the column portion 33, for positioning the end plate portion 30 relative to the base plate portion 32. The pin 36 is positioned to straddle both the column portion 33 and the end plate portion 30. Furthermore, the column portion 33 does not necessarily have to be formed integrally with the base portion 32. In this case, the column portion 33 is fastened to the base portion 32. Also, the column portion 33 is not limited to a cylindrical shape. It is sufficient that the column portion 33 forms a space with a certain width in the axial direction between the base portion 32 and the end plate portion 30.

[0039] Furthermore, multiple through holes 30c and 32b are formed in the end plate portion 30 and the base plate portion 32, into which the crankshaft 46 of the reduction output unit 18, which will be described later, is inserted (for example, three in this embodiment). The through holes 30c and 32b are arranged at equal intervals in the circumferential direction.

[0040] <Deceleration output section> The reduction output unit 18 comprises a plurality of transmission gears 44 (for example, three in this embodiment) that mesh with the teeth 76c of the first operating output shaft 76a, a plurality of crankshafts 46 (for example, three in this embodiment) with one end fixed to the transmission gears 44, and a first external gear (an example of an external gear member according to the claim) 48a and a second external gear (an example of an external gear member according to the claim) 48b that oscillate in conjunction with the rotation of the crankshafts 46.

[0041] Since a transmission gear 44 is fixed to one end of the crankshaft 46, the rotation of the first operating output shaft 76a is transmitted to the crankshaft 46 via the transmission gear 44. The crankshaft 46 is positioned along the axial direction. That is, the crankshaft 46 rotates about a crank rotation axis (an example of another rotation axis in the claims) C4 which is parallel to the second rotation axis C2. The crankshaft 46 is rotatably supported on the end plate portion 30 via a first crank bearing 51. The crankshaft 46 is also rotatably supported on the base portion 32 via a second crank bearing 52. The first crank bearing 51 and the second crank bearing 52 are, for example, tapered roller bearings.

[0042] At the axial center of the crankshaft 46, a first eccentric portion 46a and a second eccentric portion 46b are formed, eccentric to the axis of the crankshaft 46. The first eccentric portion 46a and the second eccentric portion 46b are arranged adjacent to each other in the axial direction between the first crank bearing 51 and the second crank bearing 52. The first eccentric portion 46a is adjacent to the first crank bearing 51. The second eccentric portion 46b is adjacent to the second crank bearing 52. Furthermore, the first eccentric portion 46a and the second eccentric portion 46b are offset from each other by a phase angle. These crankshafts 46 are inserted into the through holes 30c and 32b of the end plate portion 30 and the base plate portion 32, respectively. In other words, the crankshafts 46 are also arranged at equal intervals in the circumferential direction, similar to the through holes 30c and 32b.

[0043] Furthermore, a first roller bearing 55a is attached to the first eccentric portion 46a of the crankshaft 46. A second roller bearing 55b is attached to the second eccentric portion 46b. The first roller bearing 55a is, for example, a cylindrical roller bearing. The first roller bearing 55a has a plurality of rollers 56 and a cage 57 that holds the plurality of rollers 56. The second roller bearing 55b has the same configuration as the first roller bearing 55a, so a detailed explanation of it is omitted. The first external gear 48a and the second external gear 48b are oscillating and rotating in conjunction with the rotation of the crankshaft 46 via each of the roller bearings 55a and 55b.

[0044] The first external gear 48a and the second external gear 48b are positioned in the space between the base portion 32 and the end plate portion 30 of the carrier 14. The first external gear 48a and the second external gear 48b have external teeth 49a and 49b that mesh with the internal teeth 24 of the case 11. The first external gear 48a and the second external gear 48b are formed with a first through hole 48c into which the column portion 33 is inserted, and a second through hole 48d into which the eccentric portions 46a and 46b of the crankshaft 46 are inserted.

[0045] The first eccentric portion 46a and the first roller bearing 55a of the crankshaft 46 are inserted into the second through hole 48d of the first external gear 48a. The second eccentric portion 46b of the crankshaft 46 and the second roller bearing 55b are inserted into the second through hole 48d of the second external gear 48b. As a result, the first eccentric portion 46a and the second eccentric portion 46b oscillate as the crankshaft 46 rotates, and the first external gear 48a and the second external gear 48b oscillate while meshing with the internal teeth 24 of the case 11.

[0046] <Operation of the drive transmission system> Next, the operation of the drive transmission device 1 will be explained. When the motor 120 mounted on the arm 109 is driven, the rotation of the motor shaft 120a is transmitted to the first bevel gear 71 of the drive transmission device 1 via the transmission shaft 121. Then, the second bevel gear 72 that meshes with the first bevel gear 71 is rotated. Furthermore, the differential case 73 fixed to the second bevel gear 72 is rotated. As a result, the pinion gear 74 is rotated around the second rotation axis C2. This causes the pair of side gears 75a and 75b that mesh with the pinion gear 74 to rotate.

[0047] Of the pair of side gears 75a and 75b, the rotation of the first side gear 75a is transmitted to the first reduction unit 3A via the first operating output shaft 76a. Of the pair of side gears 75a and 75b, the rotation of the second side gear 75b is transmitted to the second reduction unit 3B via the second operating output shaft 76b. The operation of the first reduction unit 3A of the two reduction units 3A and 3B will be described below.

[0048] In the first reduction unit 3A, the rotation of the first operating output shaft 76a causes the transmission gear 44 that meshes with the first operating output shaft 76a to rotate. As a result, the crankshaft 46 rotates integrally with the transmission gear 44 around the crank rotation axis C4. As the crankshaft 46 rotates, the first external gear 48a rotates while meshing with the internal teeth 24 as the first eccentric portion 46a oscillates. Similarly, the second external gear 48b rotates while meshing with the internal teeth 24 as the second eccentric portion 46b oscillates. In other words, the crankshaft 46 rotates around the crank rotation axis C4 and revolves around the second rotation axis C2.

[0049] In this embodiment, the column portion 33 that penetrates the first through-hole 48c of both external gears 48a and 48b is fixed in place together with the base portion 32. As a result, the carrier 14 rotates around the second rotation axis C2 relative to the case 11 at a rotational speed reduced from that of the first operating output shaft 76a. The other end 109b of the arm 109 is fixed to the case 11 via the housing 4. The mounting bracket 110a of the bucket 110 is fixed to the end plate portion 30 of the carrier 14. Therefore, by driving the motor 120 provided on the arm 109, the bucket 110 is rotated relative to the arm 109 around the second rotation axis C2.

[0050] In other words, the respective operating output shafts 76a and 76b of each reduction unit 3A and 3B are input shafts to which the rotation of the motor shaft 120a is input via the differential gear 2. It can also be said that each operating output shaft 76a and 76b is connected to the drive shaft of the differential gear 2. Furthermore, the carrier 14 is an output shaft that reduces the rotation of the operating output shafts 76a and 76b and outputs it to the bucket 110.

[0051] Here, the rotation of the motor shaft 120a of the motor 120 is transmitted to two reduction units 3A and 3B via the transmission shaft 121 and the differential gear 2. The outputs of these two reduction units 3A and 3B are transmitted to the bucket 110. Incidentally, due to slight manufacturing and assembly errors in the parts of the two reduction units 3A and 3B, the meshing timing of each part may differ. Therefore, at the initial operation of the differential 2 (the initial operation of the drive transmission device 1), the load on the respective operating output shafts 76a and 76b connected to the two reduction units 3A and 3B may differ. In such cases, there is a high possibility that the reduction units 3A and 3B will continue to operate with an uneven load distribution.

[0052] Here, the pinion gear 74 of the differential 2 is rotatably supported in the differential case 73 with respect to the third rotation axis C3. Therefore, when the load on each operating output shaft 76a and 76b is different, the pinion gear 74 rotates around the third rotation axis C3, absorbing the difference in load on each operating output shaft 76a and 76b. After this, a uniform load is applied to each operating output shaft 76a and 76b, and in this state, the rotation of the transmission shaft 121 is transmitted to each reduction unit 3A and 3B.

[0053] As described above, in the first embodiment, the drive transmission device 1 comprises a differential 2 to which the rotation of the motor 120 is transmitted, and two reduction units 3A and 3B that reduce and output the rotation of each operating output shaft 76a and 76b of the differential 2. The two reduction units 3A and 3B have parallel (same rotation axis direction) rotation axes (second rotation axis C2) of the operating output shafts 76a and 76b as input shafts and rotation axis (second rotation axis C2) of the carrier 14 as an output shaft. Furthermore, the two reduction units 3A and 3B are arranged opposite each other along the axial direction (direction parallel to the second rotation axis C2). Therefore, two reduction units 3A and 3B to which the rotation from the differential 2 is transmitted can be provided in a space-saving manner for one differential 2, thus enabling miniaturization of the drive transmission device 1. By providing two reduction gears 3A and 3B, the load can be distributed to these two reduction gears A and 3B, thereby obtaining sufficient mechanical strength for the drive transmission device 1.

[0054] The differential gear 2 is positioned between the two reduction gears 3A and 3B. By effectively utilizing the limited space in this way, the differential gear 2 and the two reduction gears 3A and 3B can be positioned, further miniaturizing the drive transmission device 1. As a result, the drive transmission device 1 can be positioned even in narrow spaces, such as the connection between the arm 109 and the bucket 110. A differential gear 2 is used as a means to transmit the rotation of the motor 120 to the two reduction units 3A and 3B. As a result, a uniform load is applied to each of the operating output shafts 76a and 76b, and the rotation of the transmission shaft 121 is transmitted to each of the reduction units 3A and 3B in this state. Therefore, it is possible to prevent the reduction units 3A and 3B from continuing to operate while an imbalance in the load occurs. As a result, the product life of the drive transmission device 1 can be extended.

[0055] Each reduction unit 3A and 3B comprises a cylindrical case 11, a carrier 14 positioned radially inside the case 11, and a reduction output unit 18 that rotates the carrier 14 at a rotational speed reduced by a constant ratio to the rotational speed of each operating output shaft 76a and 76b, which serve as input shafts. The reduction output unit 18 comprises a plurality of crankshafts 46 and a first external gear 48a and a second external gear 48b that oscillate in conjunction with the rotation of the crankshafts 46. As a result, high output can be obtained with a high reduction ratio by the two reduction units 3A and 3B, allowing the boom 108, arm 109, and bucket 110 to operate smoothly while miniaturizing the drive transmission device 1. Furthermore, since the reduction units 3A and 3B have a high simultaneous meshing ratio between the internal teeth 24 and each external gear 48a and 48b, the drive transmission device 1 can be made more resistant to overloads and shock loads. As a result, the resistance of the connection between the slewing body 103 and the boom 108, the connection between the boom 108 and the arm 109, and the connection between the arm 109 and the bucket 110 to overload and impact loads can be improved.

[0056] [Second Embodiment] <Drive transmission system> Next, a second embodiment will be described based on Figure 5. Note that components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 5 is a schematic diagram of the drive transmission device 201 of the second embodiment, specifically the part corresponding to the differential device 202. Figure 5 corresponds to Figure 3 described above. As shown in Figure 5, the drive transmission device 201 includes a clutch mechanism (an example of an overload protection device in the claims) 80 located within the differential device 202. This is a difference from the first embodiment described above.

[0057] The clutch mechanism 80 is located within the differential case 73. The clutch mechanism 80 is configured to connect two side gears 75a and 75b. The side gears 75a and 75b rotate together with their corresponding operating output shafts 76a and 76b. Therefore, the connection of the two side gears 75a and 75b by the clutch mechanism 80 is equivalent to the connection of the respective operating output shafts 76a and 76b by the clutch mechanism 80. The clutch mechanism 80 comprises a clutch plate 81 and a pusher plate 82 facing each other in the second rotation axis direction C2, and a spring 83 that presses the pusher plate 82 toward the clutch plate 81. In this second embodiment, for example, the clutch plate 81 is connected to the second side gear 75b, and the pusher plate 82 is positioned on the first side gear 75a side.

[0058] Under this configuration, when the difference in load on the two side gears 75a and 75b (operating output shafts 76a and 76b) is below a certain value, the pusher plate 82 remains pressed toward the clutch plate 81 by the spring 83. In this state, the clutch plate 81 and the pusher plate 82 are connected, and the two side gears 75a and 75b (operating output shafts 76a and 76b) rotate together as a single unit. As a result, the rotation of the motor shaft 120a is transmitted to the respective reduction units 3A and 3B via the operating output shafts 76a and 76b without the differential gear 2 being activated (the pinion gear 74 does not rotate around the third rotation axis C3).

[0059] In response to this, when the difference in load on the two side gears 75a and 75b (operating output shafts 76a and 76b) exceeds a certain value, the pusher plate 82 is separated from the clutch plate 81 against the spring force of the spring 83. As a result, the connection between the clutch plate 81 and the pusher plate 82 is released, and the two side gears 75a and 75b (operating output shafts 76a and 76b) rotate relative to each other. In this case, the differential gear 2 is activated to absorb the difference in load on each operating output shaft 76a and 76b. After this, the rotation of the motor shaft 120a is transmitted to the respective reduction units 3A and 3B via the operating output shafts 76a and 76b.

[0060] As described above, in the second embodiment, the two side gears 75a and 75b (operating output shafts 76a and 76b) are connected via the clutch mechanism 80. Therefore, in addition to the same effects as in the first embodiment described above, it is possible to suppress unnecessary operation of the differential gear 2 when, for example, the two reduction units 3A and 3B are driven with almost no load imbalance. If the differential gear 2 is constantly operating, the driving noise and micro-vibrations of the differential gear 2 will increase, and the product life of the drive transmission device 1 will also decrease. For this reason, the drive transmission device 201 equipped with the clutch mechanism 80 can extend the product life compared to the first embodiment described above.

[0061] It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications to the embodiments described above without departing from the spirit of the present invention. For example, in the above embodiment, the drive transmission device 1,201 for driving the bucket 110 relative to the arm 109 was described in the case where the motor 120 is provided on the arm 109. On the other hand, when driving the boom 108 relative to the slewing body 103, the motor 120 can be provided on either the slewing body 103 or the boom 108. Also, when driving the arm 109 relative to the boom 108, the motor 120 can be provided on either the boom 108 or the arm 109.

[0062] In the above embodiment, we described a case where a drive transmission device 1,201 is provided to a construction machine, the excavator 100, for driving the boom 108, arm 109, and bucket 110 of the excavator 100. However, it is not limited to this, and the drive transmission device 1,201 can be used in various devices. For example, when the drive transmission device 1,201 is provided to something other than a construction machine, various things can be used as the drive source instead of the motor 120. For example, although the motor 120 was described as an electric motor, it may also be a hydraulic motor driven by hydraulic fluid. An engine or the like may be used instead of these motors.

[0063] In the above-described embodiment, the drive transmission device 1,201 was described in a case where it is equipped with two reduction units 3A and 3B that reduce the rotation of each operating output shaft 76a and 76b before outputting the result. However, it is not limited to this, and instead of the reduction units 3A and 3B, it may be equipped with a speed-increasing unit that increases the rotation speed of each operating output shaft 76a and 76b. Any unit that changes the rotation speed of each operating output shaft 76a and 76b is acceptable. However, the reduction unit is configured such that the input shaft and the output shaft are provided along the same rotation axis direction and are arranged opposite each other in the axial direction.

[0064] In the above-described embodiment, a differential gear 2 was provided as a transmission unit for transmitting the rotation of the motor shaft 120a to each reduction unit 3A and 3B. However, the invention is not limited to this, and any configuration that can transmit the rotation of the motor shaft 120a to each reduction unit 3A and 3B is acceptable as a transmission unit.

[0065] In the embodiments described above, the reduction units 3A and 3B were described as comprising a cylindrical case 11, a carrier 14 arranged radially inside the case 11, and a reduction output unit 18 that rotates the carrier 14 at a rotational speed reduced by a constant ratio to the rotational speed of each operating output shaft 76a and 76b, which serve as input shafts. The reduction output unit 18 was described as a so-called eccentric oscillating type reduction unit comprising a plurality of crankshafts 46 and a first external gear 48a and a second external gear 48b that oscillate in conjunction with the rotation of the crankshafts 46. However, the reduction units 3A and 3B may include a first member (e.g., a case 11) and a second member (e.g., a carrier 14) that rotate relative to each other around the same second rotation axis C2, and at least one crankshaft (e.g., a crankshaft 46) positioned between the first member and the second member, which rotates around a rotation axis along the second rotation axis C2 in response to the rotation of the input shaft (e.g., operating output shafts 76a and 76b). The reduction output unit 18 may be an eccentric oscillating type reduction unit that reduces the rotation of the crankshaft and transmits it to the second member, thereby reducing the rotation of the second member relative to the first member.

[0066] For example, let's describe in more detail an eccentric oscillating type reduction gear having a single crankshaft. In this case, the reduction gear has a so-called center crankshaft that is coaxial with the second rotation axis C2 as the crankshaft. As this center crankshaft rotates, the first external gear 48a and the second external gear 48b are rotated in an oscillating motion.

[0067] Among the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective. [Explanation of Symbols]

[0068] 1,201… Drive transmission device 2,202… Differential gear (transmission unit) 2a…Drive shaft 3A...First reduction unit (speed change unit) 3B…Second reduction section (shifting section) 11… Case 14…Carrier (output axis) 24…Inner teeth 26…Main bearing (bearing) 46... Crank axle 48a...First external gear (external gear member) 48b...Second external gear (external gear member) 72...Second bevel gear (ring gear) 76a...First operating output shaft (input shaft) 76b...Second operating output shaft (input shaft) 80...Clutch mechanism (overload protection device) 100... Shovel (construction machinery) 109... Arm (first component) 110... Bucket (second component) 120...Motor (drive source) 120a...Motor shaft (drive source) C2…Second axis of rotation (axis of rotation) C4... Crank rotation axis (other rotation axes)

Claims

1. one transmission unit to which rotation of a drive source that generates a rotational force is transmitted; two transmission units each having an input shaft connected to the transmission unit and an output shaft that changes the speed of rotation of the input shaft and outputs the rotation; Equipped with The two transmission units have the input shaft and the output shaft arranged along the same rotational axis direction and are disposed opposite each other along the rotational axis direction. Drive transmission device.

2. The transmission unit is disposed between the two transmission units. The drive transmission device according to claim 1 .

3. the transmission unit includes a differential device having a ring gear to which rotation of the drive source is transmitted, The input shaft is connected to the drive shaft of the differential device. The drive transmission device according to claim 2 .

4. an overload protection device that connects the input shafts of the transmission units and rotates the input shafts relative to each other when a torque difference between the input shafts exceeds a certain value; The drive transmission device according to claim 3 .

5. the transmission unit includes at least one crankshaft that receives rotation of the input shaft and rotates around another rotational axis direction parallel to the rotational axis direction, an eccentric oscillating type transmission unit that reduces the rotation of the crankshaft and transmits it to the output shaft, and rotates the output shaft at a reduced speed relative to the input shaft; The drive transmission device according to any one of claims 1 to 4.

6. The crankshaft has a plurality of the crankshafts, an external teeth member having external teeth that is oscillated and rotated about the rotation axis by the crankshaft; a case having internal teeth that mesh with the external teeth; Equipped with The output shaft is a carrier that rotatably supports the crankshaft and is rotatably supported by the case via a bearing, and is rotated by the crankshaft at a reduced speed relative to the case. The drive transmission device according to claim 5 .

7. a differential device having a ring gear to which rotation of the motor is transmitted; two transmission units disposed on either side of the differential device, each having an input shaft connected to a drive shaft of the differential device, and an output shaft that changes the speed of rotation of the input shaft and outputs the rotation; Preparation, the transmission unit includes at least one crankshaft that receives rotation of the input shaft and rotates around another rotational axis direction parallel to the rotational axis direction of the input shaft, an eccentric oscillating type transmission unit that reduces the rotation of the crankshaft and transmits it to the output shaft, and rotates the output shaft at a reduced speed relative to the input shaft; Drive transmission device.

8. a first member having a drive source that generates a rotational force; a second member connected to the first member via a drive transmission device so as to be rotatable about a rotation axis; Equipped with The drive transmission device is a transmission unit to which the rotational force of the drive source is transmitted; two speed change units that change the speed of the rotation of the transmission unit and output the rotation to the second member; Preparation, The two speed change units each include an input shaft connected to the transmission unit and an output shaft connected to the second member, and the input shaft and the output shaft are disposed along the rotation axis and opposed to each other in the direction of the rotation axis. Construction machinery.

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