Joint mechanism for construction machine

Abstract

To provide a joint mechanism for a construction machine capable of suppressing foreign matter from entering a power transmission mechanism.SOLUTION: A joint mechanism is provided with: a first bracket 10 having a first opposite face 14A; a second bracket 20 that is rotatable relative to the first bracket 10 around a rotational axis and has a second opposite face 20A opposing the first opposite face 14A; a power transmission mechanism 106 that transmits rotational power to the second bracket 20; a first annular wall 16 that projects from the first opposite face 14A and is centered on the rotational axis; and a second arc-shaped wall 27 that projects from the second opposite face 20A and is centered on the rotational axis. The power transmission mechanism 106 is positioned inside the first wall 16 in a radial direction centered on the rotational axis, and the second wall 27 is positioned outside the first wall 16 in the radial direction and at least partially overlaps the first wall 16 in a direction along the rotational axis.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This invention relates to a joint mechanism of construction machinery.

Background Art

[0002] The excavator disclosed in Patent Document 1 includes a self-propelled body, an arm extending from the body, an excavation bucket, and a power transmission mechanism. The bucket is connected to the tip of the arm. The power transmission mechanism is located at the connection point between the bucket and the arm. The bucket rotates with respect to the arm by receiving power from the power transmission mechanism.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an excavator such as that of Patent Document 1, for example, foreign matter such as earth and sand may adhere to the connection point between the bucket and the arm. If a large amount of such foreign matter enters the power transmission mechanism, it may hinder the operation of the power transmission mechanism. Note that the same problem can occur not only at the connection point between the arm and the bucket, but also in any construction machinery having a configuration in which a power transmission mechanism is located at the connection point between two components, not limited to excavators.

Means for Solving the Problems

[0005] The articulation mechanism of a construction machine for solving the above problems includes a first member having a first opposing surface, a second member that is rotatable with respect to the first member about a rotation axis and has a second opposing surface opposing the first opposing surface, a power transmission mechanism that transmits rotational power to the second member, an annular first wall that protrudes from the first opposing surface and is centered on the rotation axis, and an arcuate second wall that protrudes from the second opposing surface and is centered on the rotation axis. The power transmission mechanism is located inside the first wall in the radial direction centered on the rotation axis. The second wall is located outside the first wall in the radial direction and at least partially overlaps the first wall in the direction along the rotation axis.

[0006] In the above configuration, the first wall and the second wall are alternately arranged in a staggered manner on the radially outer side of the power transmission mechanism. In this way, by doubly guarding the power transmission mechanism from the radially outer side, it is possible to suppress foreign matter from reaching the power transmission mechanism.

[0007] The articulation mechanism of a construction machine includes an annular third wall that protrudes from the second opposing surface and is centered on the rotation axis. The third wall may be located between the power transmission mechanism and the first wall in the radial direction and at least partially overlap the first wall in the direction along the rotation axis.

[0008] In the articulation mechanism of a construction machine, the second wall may extend over 180 degrees or more about the rotation axis. In the articulation mechanism of a construction machine, the second member has a bucket having an opening. When the direction perpendicular to the opening surface of the bucket and facing outward from the inside of the bucket through the opening surface is defined as the opening direction, and when a virtual straight line connecting the shortest distance between the rotation axis and the opening surface is defined as the first straight line and a virtual straight line extending from the rotation axis in the opening direction is defined as the second straight line when viewed in the direction along the rotation axis, the second wall may extend over the entire angular range from the first straight line to the second straight line in the circumferential direction about the rotation axis and on the side where the opening surface is open.

[0009] The joint mechanism of the construction machine may include a first stopper protruding from the first member and a second stopper protruding from the second member and contacting the first stopper when the second member rotates within a predetermined range in a first rotation direction from a predetermined reference position.

[0010] The joint mechanism of the construction machine may include a third stopper protruding from the second member and contacting the first stopper when the second member rotates within the predetermined range in a direction opposite to the first rotation direction from the reference position.

[0011] The joint mechanism of the construction machine includes a power source that applies power to the power transmission mechanism and a control device that controls the power source. The control device can receive a switching signal from outside the control device and switch between a first mode in which the power output by the power source is limited to less than a specified value and a second mode in which the power output by the power source is allowed to be equal to or greater than the specified value based on the switching signal.

[0012] A joint mechanism of a construction machine for solving the above problems includes a first member, a second member rotatable with respect to the first member, a first stopper protruding from the first member, and a second stopper protruding from the second member and contacting the first stopper when the second member rotates within a predetermined range from a predetermined reference position.

[0013] In the above configuration, by rotating the second member and causing the second stopper to collide with the first stopper, an impact can be applied to the first member and the second member. By applying an impact to the first member and the second member, foreign matter can be removed from the first member and the second member. Therefore, foreign matter can be quickly removed from the first member and the second member. And if foreign matter can be removed from the first member and the second member, for example, when a power transmission mechanism for rotating the second member is located around the first member and the second member, it is possible to prevent foreign matter from reaching the power transmission mechanism.

[0014] The articulation mechanism of a construction machine includes a power transmission mechanism that rotatably connects the first member and the second member and transmits the power of rotation to the second member, and the second member may have a bucket having an opening.

[0015] In the articulation mechanism of a construction machine, the second member has a bucket having an opening, and the direction perpendicular to the opening surface of the bucket and from the inside to the outside of the bucket through the opening surface is defined as the opening direction. When viewed in the direction along the rotation axis of the second member, at the position where the second stopper contacts the first stopper, a virtual semi-straight line extending in the opening direction from the opening surface and in the direction opposite to the first stopper starting from the rotation axis may be located.

Advantages of the Invention

[0016] In the above technical idea, it is possible to prevent foreign matter from reaching the power transmission mechanism.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0018] <Overall Configuration> As shown in FIG. 1, the excavator 500 includes a main body 502, a boom 504, and a bucket articulation mechanism 510. The main body 502 includes a crawler 502A for traveling and a vehicle body 502B including a driver's seat. The boom 504 extends from the vehicle body 502B. The boom 504 connects the vehicle body 502B and the bucket articulation mechanism 510. The boom 504 is rotatable with respect to the vehicle body 502B about the end of the boom 504 on the vehicle body 502B side.

[0019] <Bucket Articulation Mechanism> As shown in FIG. 1, the bucket articulation mechanism 510 includes an arm 520. The arm 520 is a first member. The arm 520 includes an arm main body 521 and a first bracket 10.

[0020] The arm main body 521 is elongated. One end in the longitudinal direction of the arm main body 521 is connected to the boom 504. The arm main body 521 is relatively rotatable with respect to the boom 504 about one end of the arm main body 521.

[0021] The first bracket 10 is located on the side of the arm main body 521 opposite to the side connected to the boom 504. As shown in FIG. 2, the first bracket 10 includes a base portion 12 and a holding portion 14.

[0022] As shown in FIG. 1, the base portion 12 extends from the tip in the longitudinal direction of the arm main body 521 to the side opposite to the arm main body 521. As shown in FIG. 2, the base portion 12 is plate-shaped. The width of the main surface of the base portion 12 increases as it is away from the arm main body 521. Note that the main surface of the base portion 12 is the two surfaces with the largest area among the base portion 12.

[0023] As shown in FIG. 2, the holding portion 14 is annular. The outer peripheral surface of the holding portion 14 is connected to the end of the base portion 12 on the side opposite to the arm main body 521. As shown in FIG. 3, one of the two directions along the central axis of the holding portion 14 is referred to as the first direction X1, and the other is referred to as the second direction X2. Then, these first direction X1 and second direction X2 are collectively referred to as the axial direction XA. The axial direction XA coincides with the direction along the thickness of the base portion 12. Hereinafter, the central axis of the holding portion 14 is referred to as the base rotation axis P. And the radial direction centered on this base rotation axis P is simply referred to as the radial direction. Also, the circumferential direction centered on the base rotation axis P is simply referred to as the circumferential direction.

[0024] As shown in FIGS. 2 and 4, the bucket joint mechanism 510 includes a first wall 16. The first wall 16 protrudes in the first direction X1 from the first opposing surface 14A which is the end surface in the first direction X1 of the holding portion 14. In the present embodiment, the first wall 16 is an integrally formed object with the holding portion 14. The first wall 16 is annular with the base rotation axis P as the center. The width of the first wall 16 in the radial direction is constant over the entire circumferential direction. The inner diameter of the first wall 16 coincides with the inner diameter of the holding portion 14. And the inner peripheral surface of the first wall 16 is flush with the inner peripheral surface of the holding portion 14.

[0025] <Drive unit> As shown in FIG. 3, the bucket joint mechanism 510 includes a drive unit 100. The drive unit 100 is held by the holding portion 14 of the first bracket 10. The drive unit 100 includes a housing 102, a motor 104, and a power transmission mechanism 106. Note that FIG. 3 schematically shows the arrangement of each component of the bucket joint mechanism 510. For example, the size relationship between the motor 104 and other components does not necessarily match the actual one.

[0026] The housing 102 houses a motor 104. The motor 104 is electric. The motor 104 includes a motor body 104A and an output shaft 104B. The motor body 104A is fixed to the housing 102. The output shaft 104B protrudes from the motor body 104A in the first direction X1. The output shaft 104B is rotatable with respect to the motor body 104A. The output shaft 104B is rotatable in both forward and reverse directions. Although not shown, a plurality of teeth are formed on the outer peripheral surface of the output shaft 104B. The motor 104 is a power source that supplies power to a power transmission mechanism 106.

[0027] <Power transmission mechanism> The power transmission mechanism 106 is located in the first direction X1 with respect to the motor 104. The power transmission mechanism 106 is a speed reducer that reduces the rotation of the output shaft 104B of the motor 104 at a predetermined gear ratio and outputs it.

[0028] The power transmission mechanism 106 includes a case 60. The case 60 includes a case body 62, a plurality of teeth 64, and a flange 66. The case body 62 is located in the first direction X1 with respect to the housing 102. The case body 62 is cylindrical. The case body 62 is located inside the holding portion 14 of the first bracket 10 in the radial direction. The outer diameter of the case body 62 substantially coincides with the inner diameter of the holding portion 14. The central axis of the case body 62 substantially coincides with the base rotation axis P. That is, the base rotation axis P is also the central axis of the power transmission mechanism 106. The end of the case body 62 in the first direction X1 is located substantially at the same position as the end of the holding portion 14 in the first direction X1. The case body 62 is covered by the housing 102 from the second direction X2.

[0029] The plurality of teeth 64 protrude from the inner peripheral surface of the case body 62. The plurality of teeth 64 are arranged at equal intervals in the circumferential direction. In the axial direction XA, the teeth 64 are located near the center of the case body 62.

[0030] The flange 66 protrudes from the outer peripheral surface of the case body 62. The flange 66 is annular. The outer diameter of the flange 66 substantially coincides with the outer diameter of the holding portion 14 in the first bracket 10. The end face of the flange 66 in the first direction X1 faces the end face of the holding portion 14 in the second direction X2. The flange 66 and the holding portion 14 are fixed by bolts B1 at a plurality of locations.

[0031] <Carrier> The power transmission mechanism 106 includes a carrier 70. The carrier 70 includes a first plate portion 71, a second plate portion 72, and a plurality of column portions 73. The first plate portion 71 is located inside the case body 62. The first plate portion 71 is located at a position closer to the end of the case body 62 in the first direction X1. The first plate portion 71 is disk-shaped. The diameter of the first plate portion 71 is smaller than the inner diameter of the case body 62. The central axis of the first plate portion 71 substantially coincides with the base rotation axis P. The end of the first plate portion 71 in the first direction X1 slightly protrudes in the first direction X1 with respect to the end of the case body 62 in the first direction X1. The end of the first plate portion 71 in the second direction X2 is located in the first direction X1 with respect to the tooth 64 of the case 60. A bearing Y1 is interposed between the outer peripheral surface of the first plate portion 71 and the inner peripheral surface of the case body 62. Note that the first plate portion 71 includes a plurality of through holes 71H. The number of through holes 71H is, for example, three. In the radial direction, the through holes 71H are located at positions deviated from the base rotation axis P. The through holes 71H penetrate the first plate portion 71 in the axial direction XA. The plurality of through holes 71H are arranged at equal intervals in the circumferential direction.

[0032] The second plate portion 72 is located inside the case body 62. The second plate portion 72 is located at a position closer to the end of the case body 62 in the second direction X2. The second plate portion 72 is disc-shaped. The diameter of the second plate portion 72 is the same as the diameter of the first plate portion 71. The central axis of the second plate portion 72 substantially coincides with the base rotation axis P. The end of the second plate portion 72 in the second direction X2 is located at substantially the same position as the end of the case body 62 in the second direction X2. The end of the second plate portion 72 in the first direction X1 is located in the second direction X2 with respect to the teeth 64 of the case 60. A bearing Y1 is interposed between the outer peripheral surface of the second plate portion 72 and the inner peripheral surface of the case body 62. The second plate portion 72 is provided with a plurality of through holes 72H. The plurality of through holes 72H are provided in pairs with the plurality of through holes 71H provided in the first plate portion 71. That is, the number of the through holes 72H is the same as the number of the through holes 71H of the first plate portion 71. The through holes 72H penetrate the second plate portion 72 in the axial direction XA. The central axis of the through hole 72H substantially coincides with the central axis of the paired through hole 71H in the first plate portion 71.

[0033] The plurality of column portions 73 project from the second plate portion 72 in the first direction X1. In the radial direction, the column portions 73 are located at positions deviated from the base rotation axis P. The column portions 73 are columnar. Also, the plurality of column portions 73 are arranged at equal intervals in the circumferential direction. The column portions 73 are integrally formed with the second plate portion 72. The end surface of the column portion 73 in the first direction X1 is in contact with the first plate portion 71. That is, the column portions 73 connect the first plate portion 71 and the second plate portion 72. And the column portions 73 and the first plate portion 71 are fixed with bolts B2.

[0034] <External gear> The power transmission mechanism 106 includes a first external gear 91. The first external gear 91 is located inside the case body 62. In the axial direction XA, the first external gear 91 is located between the first plate portion 71 and the second plate portion 72 of the carrier 70. Specifically, in the axial direction XA, the first external gear 91 is located at the same position as the teeth 64 of the case 60. The first external gear 91 is generally disc-shaped. The diameter of the first external gear 91 is smaller than the inner diameter of the case body 62. The central axis of the first external gear 91 is parallel to the base rotation axis P. A plurality of teeth are formed on the outer peripheral surface of the first external gear 91. The plurality of teeth are arranged at equal intervals in the circumferential direction. In FIG. 3, the illustration of the teeth of the first external gear 91 is omitted. Among the plurality of teeth, the teeth located in a partial range in the circumferential direction are engaged with the teeth 64 of the case 60. On the other hand, there is a gap between the teeth located outside the above range in the circumferential direction among the plurality of teeth and the teeth 64 of the case 60.

[0035] The first external gear 91 includes a plurality of first through holes 91A. In the radial direction, the first through holes 91A are located at positions deviated from the central axis of the first external gear 91. The first through holes 91A penetrate the first external gear 91 in the axial direction XA. The first through holes 91A are provided corresponding to the respective column portions 73. And the column portions 73 penetrate through the first through holes 91A. Note that the diameter of the first through holes 91A is larger than the diameter of the column portions 73.

[0036] The first external gear 91 includes a plurality of second through holes 91B. The plurality of second through holes 91B are provided in pairs with the plurality of through holes 71H provided in the first plate portion 71. That is, the number of the second through holes 91B is the same as the number of the through holes 71H provided in the first plate portion 71. In the radial direction, the second through holes 91B are located at positions deviated from the central axis of the first external gear 91. The second through holes 91B penetrate the first external gear 91 in the axial direction XA. The second through holes 91B communicate with the paired through holes 71H in the first plate portion 71.

[0037] The power transmission mechanism 106 includes a second external gear 92. The second external gear 92 is located inside the case body 62. The second external gear 92 is adjacent to the first external gear 91 in the axial direction XA. That is, the second external gear 92, like the first external gear 91, is located between the first plate portion 71 and the second plate portion 72 of the carrier 70 in the axial direction XA. Also, the second external gear 92 is located at the same position as the teeth 64 of the case 60 in the axial direction XA. The configuration of the second external gear 92 is the same as that of the first external gear 91. That is, the second external gear 92 includes a first through hole 92A for each column portion 73. Further, the second external gear 92 includes a plurality of second through holes 92B that form a pair with a plurality of through holes 72H provided in the second plate portion 72. The second through holes 92B communicate with the paired through holes 72H in the second plate portion 72. At the same time, the second through holes 92B also communicate with the second through holes 91B of the first external gear 91. As a result, the through hole 71H of the first plate portion 71, the second through hole 91B of the first external gear 91, the second through hole 92B of the second external gear 92, and the through hole 72H of the second plate portion 72 form a continuous shaft hole. There are a plurality of shaft holes corresponding to the number of through holes 71H of the first plate portion 71. At the same time, the shaft holes are arranged at equal intervals in the circumferential direction.

[0038] <transmission shaft> The power transmission mechanism 106 includes a plurality of transmission shafts 80. The transmission shafts 80 are provided for each shaft hole. The transmission shaft 80 includes a main shaft 81, a first eccentric portion 83, and a second eccentric portion 85.

[0039] The main shaft 81 is cylindrical. The main shaft 81 extends in the axial direction XA. Most of the main shaft 81 is located in the shaft hole. Specifically, the end of the main shaft 81 in the first direction X1 is located in the through hole 71H of the first plate portion 71. Most of the main shaft 81 closer to the second direction X2 is located in the through hole 72H of the second plate portion 72. And a part of the main shaft 81 protrudes from the through hole 72H of the second plate portion 72 in the second direction X2.

[0040] The first eccentric portion 83 is located in a portion in the axial direction XA of the main shaft 81. Specifically, the first eccentric portion 83 is located within the second through hole 91B of the first external gear 91. The first eccentric portion 83 protrudes from the outer peripheral surface of the main shaft 81. In a plan view facing the axial direction XA, the outer shape of the first eccentric portion 83 is circular. In a plan view facing the axial direction XA, the center of the first eccentric portion 83 is offset from the center of the main shaft 81. A bearing Y2 is interposed between the outer peripheral surface of the first eccentric portion 83 and the second through hole 91B of the first external gear 91.

[0041] The second eccentric portion 85 is located in a portion in the axial direction XA of the main shaft 81. Specifically, the second eccentric portion 85 is located within the second through hole 92B of the second external gear 92. The second eccentric portion 85, similar to the first eccentric portion 83, protrudes from the outer peripheral surface of the main shaft 81. In a plan view facing the axial direction XA, the outer shape of the second eccentric portion 85 is circular. In a plan view facing the axial direction XA, the center of the second eccentric portion 85 is offset from the center of the first eccentric portion 83 and also from the center of the main shaft 81. A bearing Y2 is interposed between the outer peripheral surface of the second eccentric portion 85 and the second through hole 92B of the second external gear 92.

[0042] The power transmission mechanism 106 includes a plurality of transmission gears 87. The transmission gears 87 are provided for each transmission shaft 80. The transmission gears 87 are attached to a portion of the main shaft 81 that protrudes in the second direction X2 from the through hole 72H of the second plate portion 72. The transmission gears 87 are generally annular. The main shaft 81 is fixed to the central hole of the transmission gear 87. Although not shown, a plurality of teeth are formed on the outer peripheral surface of the transmission gear 87.

[0043] The transmission gear 87 meshes with the teeth of the output shaft 104B of the motor 104. The transmission gear 87 transmits the rotation of the output shaft 104B of the motor 104 to the transmission shaft 80. The transmission shaft 80 transmits its own rotation accompanying the rotation of the transmission gear 87 to the first external gear 91 and the second external gear 92 via the first eccentric portion 83 and the second eccentric portion 85. The first external gear 91 and the second external gear 92 swing and rotate under the force from the first eccentric portion 83 and the second eccentric portion 85. That is, the first external gear 91 relatively rotates with respect to the case body 62 while swinging so that the circumferential range meshing with the teeth 64 of the case 60 is interchanged. The same applies to the second external gear 92. The rotations of the first external gear 91 and the second external gear 92 are transmitted to the carrier 70 via the column portion 73. And the carrier 70 rotates about the base rotation axis P. That is, the carrier 70 relatively rotates with respect to the case 60 fixed by the first bracket 10.

[0044] <Excavating member> As shown in FIG. 1, the bucket joint mechanism 510 includes an excavating member 530. The excavating member 530 is a second member. The excavating member 530 includes a bucket 531 and a second bracket 20. The bucket 531 is box-shaped with an opening 535.

[0045] As shown in FIG. 3, the second bracket 20 is located in the first direction X1 with respect to the first bracket 10. The second bracket 20 is plate-shaped. The direction along the thickness of the second bracket 20 coincides with the axial direction XA. And the second opposing surface 20A which is one main surface of the second bracket 20 faces the second direction X2. Note that the main surfaces of the second bracket 20 are the two surfaces with the largest area among the second brackets 20.

[0046] As shown in FIG. 5, the second bracket 20 includes a first portion 21 and a second portion 22. Hereinafter, viewing the bucket joint mechanism 510 in a plane view facing the axial direction XA is referred to as a specific plane view. As shown in FIGS. 5 and 6, in the specific plane view, the second bracket 20 has a configuration in which the semi-circular first portion 21 and the second portion 22 located on the side opposite to the arc in the first portion 21 are joined together. The center of the arc of the first portion 21 is located on the base rotation axis P. The diameter of the arc of the first portion 21 is smaller than the outer diameter of the holding portion 14 of the first bracket 10 and larger than the outer diameter of the first wall 16 protruding from the first bracket 10. As shown in FIG. 6, in the specific plane view, the outer edge of the second portion 22 includes a first outer edge portion 22A extending linearly from one end of the arc of the first portion 21, a second outer edge portion 22B extending linearly from the other end of the arc of the first portion 21, and a third outer edge portion 22C linearly connecting the first outer edge portion 22A and the second outer edge portion 22B. The first outer edge portion 22A and the second outer edge portion 22B approach each other as they move away from the first portion 21. In the specific plane view, the first outer edge portion 22A is shorter than the second outer edge portion 22B. The third outer edge portion 22C is connected to the bucket 531.

[0047] As shown in FIGS. 4 and 5, from the second opposing surface 20A of the second bracket 20, a second wall 27, which is an element of the bucket articulation mechanism 510, protrudes in the second direction X2. In the present embodiment, the second wall 27 is an integrally formed product with the second bracket 20. The second wall 27 is in an arc shape centered on the base rotation axis P. Most of the second wall 27 is located in the first portion 21 of the second bracket 20. A part of the second wall 27 also reaches the second portion 22 of the second bracket 20. For example, the width of the second wall 27 in the radial direction is slightly larger than the width of the first wall 16 in the radial direction. The outer diameter of the second wall 27 is the same as the outer diameter of the first portion 21 in the second bracket 20. And, of the second wall 27, the outer peripheral surface of the portion located in the first portion 21 is flush with the outer peripheral surface of the first portion 21. The inner diameter of the second wall 27 is slightly larger than the outer diameter of the first wall 16 protruding from the first bracket 10. Note that the dimension of the second wall 27 in the axial direction XA is substantially the same as the dimension of the first wall 16 in the axial direction XA.

[0048] As shown in FIGS. 4 and 5, from the second opposing surface 20A of the second bracket 20, a third wall 28, which is an element of the bucket articulation mechanism 510, protrudes in the second direction X2. In the present embodiment, the third wall 28 is an integrally formed product with the second bracket 20. The third wall 28 is in an annular shape centered on the base rotation axis P. The third wall 28 extends across both the first portion 21 and the second portion 22 of the second bracket 20. For example, the width of the third wall 28 in the radial direction is slightly larger than the width of the second wall 27 in the radial direction. The outer diameter of the third wall 28 is slightly smaller than the inner diameter of the first wall 16. The inner diameter of the third wall 28 is slightly larger than the diameter of the first plate portion 71 of the carrier 70. Note that the dimension of the third wall 28 in the axial direction XA is substantially the same as the dimension of the second wall 27 in the axial direction XA.

[0049] As shown in FIG. 3, the second bracket 20 is fixed to the first plate portion 71 of the carrier 70. Specifically, the second opposing surface 20A of the second bracket 20 faces the surface of the first plate portion 71 facing the first direction X1. The second bracket 20 and the first plate portion 71 are fixed together with the column portion 73 by a bolt B2 that fixes the column portion 73 and the first plate portion 71 in the carrier 70. As a result of the second bracket 20 being fixed to the first plate portion 71, the second bracket 20 is rotatable together with the carrier 70 about the base rotation axis P. In this way, the second bracket 20 is transmitted with rotational power from the power transmission mechanism 106 via the carrier 70. Since the second bracket 20 is rotatable together with the carrier 70, the second bracket 20 is relatively rotatable with respect to the first bracket 10 about the base rotation axis P. In this way, the first bracket 10 and the second bracket 20 are relatively rotatably connected by the power transmission mechanism 106. The base rotation axis P forms the rotation center of the second bracket 20 and thus the excavation member 530.

[0050] As shown in FIG. 4, in a state where the second bracket 20 is fixed to the carrier 70, the second opposing surface 20A of the second bracket 20 faces the first opposing surface 14A in the holding portion 14 of the first bracket 10. And the first wall 16 protruding from the first opposing surface 14A of the first bracket 10, the second wall 27 and the third wall 28 protruding from the second opposing surface 20A of the second bracket 20 are arranged alternately in the radial direction. Hereinafter, this point will be described in detail. As described above, the end of the first plate portion 71 in the first direction X1 slightly protrudes in the first direction X1 with respect to the end of the case body 62 in the first direction X1. That is, a part of the first plate portion 71 has become a protruding end portion 71A protruding from the case body 62 in the first direction X1. The third wall 28 protruding from the second bracket 20 is located radially outside with respect to this protruding end portion 71A. In the axial direction XA, the third wall 28 is located at a position overlapping substantially the entire area of the protruding end portion 71A. Further, the first wall 16 protruding from the first bracket 10 is located radially outside with respect to the third wall 28. In other words, the third wall 28 is located between the first wall 16 and the protruding end portion 71A of the first plate portion 71 in the radial direction. In the axial direction XA, the first wall 16 is located at a position overlapping substantially the entire area of the third wall 28. Further, the second wall 27 protruding from the second bracket 20 is located radially outside with respect to the first wall 16. In the axial direction XA, the second wall 27 is located at a position overlapping substantially the entire area of the first wall 16. Thus, in the circumferential range where the second wall 27 exists, the third wall 28, the first wall 16, and the second wall 27 are arranged in this order toward the outside in the radial direction with respect to the protruding end portion 71A of the first plate portion 71. And these third wall 28, first wall 16, and second wall 27 form a triple labyrinth structure. Also, as shown in the lower part of the drawing of FIG. 3, in the circumferential range where the second wall 27 does not exist, the third wall 28 and the first wall 16 are arranged in this order toward the outside in the radial direction with respect to the protruding end portion 71A. And these third wall 28 and first wall 16 form a double labyrinth structure. The space defined by the inner peripheral surface of the holding portion 14 of the first bracket 10 and the second opposing surface 20A of the second bracket 20 is referred to as the accommodation chamber 30 of the power transmission mechanism 106.In this embodiment, a triple or double labyrinth structure is formed in the gap communicating the storage chamber 30 with the outside. In the axial direction XA, there is a slight gap between the protruding ends of the first wall 16, the second wall 27, and the third wall 28 constituting the labyrinth structure and the wall surfaces facing them. For example, there is a slight gap between the protruding end of the first wall 16 and the second opposing surface 20A of the second bracket 20. Also, there is a slight gap between the protruding end of the second wall 27 and the first opposing surface 14A of the first bracket 10.

[0051] <Position of the second wall> The position of the second wall 27 in the circumferential direction will be described. As a premise, the posture of the bucket 531 integrated with the second bracket 20 will be described. As shown in FIG. 6, the bucket 531 is box-shaped with an opening 535. The direction perpendicular to the opening surface 535A of the bucket 531 and directed from the inside to the outside of the bucket 531 through the opening surface 535A is called the opening direction V. The direction perpendicular to the opening surface 535A is also the direction of the line of sight when the apparent area of the region surrounded by the opening edge of the opening 535 is the largest. Also, a virtual circle centered on the base rotation axis P is called the first virtual circle. The opening direction V is along the tangent line at the position where the first virtual circle passes through the opening surface 535A of the bucket 531. The bucket 531 is connected to the third outer edge portion 22C of the second portion 22 of the second bracket 20 in such a posture. The first outer edge portion 22A of the second portion 22 is connected to the portion of the outer peripheral wall of the bucket 531 near the opening 535. The second outer edge portion 22B of the second portion 22 is connected to the portion of the outer peripheral wall of the bucket 531 near the bottom of the bucket 531.

[0052] The position of the second wall 27 in the circumferential direction will be described in detail. Hereinafter, it is assumed that the excavation member 530 is in a state of being viewed in a specific plan view. As shown in FIG. 6, a virtual straight line connecting the shortest distance between the base rotation axis line P and the opening surface 535A is referred to as a first straight line U1. Further, a virtual straight line extending from the base rotation axis line P in the opening direction V is referred to as a second straight line U2. That is, the second straight line U2 is a half straight line extending in the opening direction V starting from the base rotation axis line P. In the circumferential direction, the second wall 27 extends over the entire specific angular range UN which is the angular range from the first straight line U1 to the second straight line U2 and is the angular range on the side where the opening surface 535A is open. Further, the second wall 27 extends not only in the specific angular range UN but also on the side opposite to the specific angular range UN with the second straight line U2 interposed therebetween. The second wall 27 extends from the vicinity of the first straight line U1 for approximately 200 degrees around the base rotation axis line P. Regarding the specific angular range UN, the side where the opening surface 535A is open can also be said to be the side pointing in the opening direction V. The specific angular range UN of the present embodiment is approximately 100 degrees.

[0053] <Stopper> As shown in FIG. 2, the bucket joint mechanism 510 includes a first stopper 51. The first stopper 51 is located at the base 12 of the first bracket 10. Of the two main surfaces of the base 12, the main surface facing the first direction X1 is referred to as a first main surface 12A. The first stopper 51 projects from the first main surface 12A in the first direction X1. The first stopper 51 is located near the center of both sides of the base 12 in a flaring shape. The first stopper 51 has a rectangular parallelepiped shape. Regarding the first direction X1, the protruding end of the first stopper 51 reaches the same position as the main surface of the second bracket 20 facing the first direction X1.

[0054] As shown in FIG. 5, the bucket joint mechanism 510 includes a second stopper 52. The second stopper 52 protrudes outward from the outer edge of the second bracket 20. The second stopper 52 is located near the boundary between the end of the arc of the first portion 21 and the second outer edge portion 22B of the second portion 22. When the second bracket 20 is viewed in a specific plane, the second stopper 52 is generally triangular in shape. That is, the second stopper 52 includes a contact surface 52A corresponding to one side of the triangle and an inclined surface 52B corresponding to the other side. The contact surface 52A protrudes generally radially from the outer edge of the second bracket 20. The inclined surface 52B is located closer to the second portion 22 of the second bracket 20 than the contact surface 52A. The inclined surface 52B connects the protruding end of the contact surface 52A and the second outer edge portion 22B of the second portion 22.

[0055] As shown in FIG. 5, the bucket joint mechanism 510 includes a third stopper 53. The third stopper 53 is provided symmetrically with the second stopper 52 across the base rotation axis P. That is, the third stopper 53 includes a contact surface 53A that protrudes radially outward from the outer edge of the second bracket 20 and an inclined surface 53B that extends from the protruding end of the contact surface 52A to the first outer edge portion 22A of the second portion 22.

[0056] As described above, the second stopper 52 and the third stopper 53 are symmetrically arranged with respect to the base rotation axis P. Therefore, as shown in FIG. 6, the contact surface 52A of the second stopper 52 and the contact surface 53A of the third stopper 53 are approximately 180 degrees apart in the circumferential direction. Here, a predetermined reference position will be described. In the circumferential direction, the position of the excavation member 530 when the distance from the second stopper 52 to the first stopper 51 is equal to the distance from the third stopper 53 to the first stopper 51 is defined as the reference position of the excavation member 530. As shown in FIG. 7, when the excavation member 530 rotates within a predetermined range in the first rotation direction from the reference position, the contact surface 52A of the second stopper 52 contacts the first stopper 51. Similarly, when the excavation member 530 rotates within a predetermined range in the second rotation direction opposite to the first rotation direction from the reference position, the contact surface 53A of the third stopper 53 contacts the first stopper 51. In the present embodiment, the predetermined range is approximately 90 degrees.

[0057] Here, as shown in FIG. 7, when the excavation member 530 is viewed in a specific plane together with the first bracket 10, a virtual half-line extending in the direction opposite to the first stopper 51 starting from the base rotation axis P is referred to as a virtual half-line U3. When the excavation member 530 is viewed in a specific plane together with the first bracket 10 and the second stopper 52 is in contact with the first stopper 51, the virtual half-line U3 is located on the opening direction V side when viewed from the opening surface 535A.

[0058] <Electrical Configuration> As shown in FIG. 1, the bucket joint mechanism 510 includes a battery 202 and an inverter 204. These battery 202 and inverter 204 are located, for example, on the vehicle body 502B. The battery 202 is electrically connected to the inverter 204 via a power line. Further, the inverter 204 is electrically connected to the motor 104 shown in FIG. 3 via a power line (not shown). The inverter 204 performs DC-AC power conversion between the battery 202 and the motor 104.

[0059] As shown in FIG. 1, the bucket joint mechanism 510 includes a first operating device 231 and a second operating device 232. The first operating device 231 and the second operating device 232 are located near the passenger seat in the vehicle body 502B. The first operating device 231 and the second operating device 232 can receive the operations of the operator of the excavator 500. The first operating device 231 is, for example, a joystick. The first operating device 231 outputs a rotation signal including information indicating the rotation drive and the rotation direction of the excavation member 530 in response to the operation of the operator. The second operating device 232 is, for example, a push switch. The second operating device 232 outputs a switching signal including information instructing to control the motor 104 in a second mode described later in response to the operation of the operator. The second operating device 232 is turned on and off by the operator. When the second operating device 232 is turned on by the operator, the output of the switching signal starts. When the second operating device 232 is turned off by the operator, the output of the switching signal stops.

[0060] The bucket joint mechanism 510 includes a control device 200. The control device 200 can be configured as one or more processors that execute various processes according to a computer program (software). Note that the control device 200 may be configured as a circuitry including one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least a part of various processes, or a combination thereof. The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores program codes or instructions configured to cause the CPU to execute processes. The memory, that is, the computer-readable medium includes any available medium accessible by a general-purpose or dedicated computer.

[0061] The control device 200 is connected to the inverter 204 by wire or wirelessly. The control device 200 controls the motor 104 by controlling the inverter 204. That is, the control device 200 targets the motor 104 for control.

[0062] The control device 200 is connected to the first operating device 231 and the second operating device 232 by wire or wirelessly. And the control device 200 can receive the signals output by the first operating device 231 and the second operating device 232. The control device 200 controls the motor 104 according to the signals from the first operating device 231 and the second operating device 232. Specifically, the control device 200 rotates the output shaft 104B of the motor 104 in either the forward or reverse direction according to the rotation signal. The control device 200 can switch between a first mode and a second mode as control modes for controlling the magnitude of the torque related to this rotation. The control device 200 switches the control mode of the motor 104 according to the presence or absence of receiving the switching signal. When the control device 200 does not receive the switching signal, it controls the motor 104 in the first mode. In the first mode, the control device 200 controls the motor 104 so that the motor 104 outputs a predetermined set torque when rotating the output shaft 104B of the motor 104 according to the rotation signal. For example, multiple levels of values are predetermined for the set torque. And the operator of the excavator 500 can switch the set torque through the operation of an operating device (not shown). The largest available set torque in the first mode is less than the specified value. That is, the first mode is a control mode that limits the torque output by the motor 104 to less than the specified value. The specified value is predetermined as the torque that can give a strong impact not required in normal excavation work when the components of the excavation member 530 collide with other objects. Along with such torque limitation, in the first mode, the rotational speed of the output shaft 104B of the motor 104 and the acceleration of the rotation of the output shaft 104B are each limited to less than a certain value. In addition, in the first mode, in addition to such torque limitation, a limitation is imposed on the rotation range of the output shaft 104B of the motor 104. The rotational position of the excavation member 530 when the second stopper 52 is located in the second rotation direction by the avoidance angle with respect to the first stopper 51 is called the first rotational position. The avoidance angle is, for example, 10 degrees. The rotational position of the excavation member 530 when the third stopper 53 is located in the first rotation direction by the above avoidance angle with respect to the first stopper 51 is called the second rotational position.In the first mode, the control device 200 restricts the rotation range of the output shaft 104B so that the excavation member 530 rotates within the range from the first rotation position to the second rotation position centered on the reference position.

[0063] On the other hand, when the control device 200 receives a switching signal, it controls the motor 104 in the second mode. In the second mode, when rotating the output shaft 104B of the motor 104 according to a rotation signal, the control device 200 controls the motor 104 so that the motor 104 outputs a predetermined allowable torque. The allowable torque is a value larger than a specified value. That is, the second mode is a control mode that allows the torque output by the motor 104 to be equal to or greater than the specified value. At the same time, in the second mode, the restrictions on the rotation speed and rotational acceleration of the output shaft 104B of the motor 104 imposed in the first mode are also released. Note that in the second mode, the control device 200 also releases the restriction on the rotation range of the output shaft 104B.

[0064] <Operation 1 of the Embodiment: Labyrinth Structure> Now, it is assumed that excavation work is being performed by the bucket 531. As the bucket 531 excavates earth and sand, earth and sand may adhere to the first bracket 10 and the second bracket 20 located around the bucket 531. A part of the earth and sand adhering to the first bracket 10 and the second bracket 20 tries to enter the accommodation chamber 30 through the gap between the first opposing surface 14A of the first bracket 10 and the second opposing surface 20A of the second bracket 20. Here, as shown in FIG. 3, in the configuration of the present embodiment, a triple or double labyrinth structure is formed between the first opposing surface 14A of the first bracket 10 and the second opposing surface 20A of the second bracket 20. These labyrinth structures prevent earth and sand from entering the accommodation chamber 30.

[0065] Specifically, as shown in FIG. 4, in the circumferential range where the triple labyrinth structure is formed, the second wall 27, the first wall 16, and the third wall 28 are alternately arranged in a staggered manner in the radial direction. When earth and sand try to enter from the outside with respect to such a structure, first, the outer peripheral surface of the second wall 27 that constitutes the outermost side of the labyrinth structure prevents the entry of this earth and sand. Suppose the second wall 27 fails to completely prevent the entry of earth and sand, and a small amount of earth and sand enters the gap between the second wall 27 and the first opposing surface 14A of the first bracket 10. Here, on the true front surface radially inside the gap between the second wall 27 and the first opposing surface 14A of the first bracket 10, the first wall 16 protruding from the first bracket 10 is located. Therefore, even if earth and sand enters radially inward from the above gap, the outer peripheral surface of the first wall 16 prevents the further entry of this earth and sand. Furthermore, suppose the first wall 16 fails to completely prevent the entry of earth and sand, and a small amount of earth and sand enters the gap between the first wall 16 and the second opposing surface 20A of the second bracket 20. Here, on the true front surface radially inside the gap between the first wall 16 and the second opposing surface 20A of the second bracket 20, the third wall 28 protruding from the second bracket 20 is located. Therefore, even if earth and sand enters radially inward from the above gap, the outer peripheral surface of the third wall 28 prevents the further entry of this earth and sand.

[0066] On the other hand, as shown in the lower part of the drawing of FIG. 3, in the circumferential range where the double labyrinth structure is formed, the first wall 16 and the third wall 28 are alternately arranged in a staggered manner in the radial direction. When earth and sand try to enter from the outside with respect to such a structure, first, the outer peripheral surface of the first wall 16 that constitutes the outermost side of the labyrinth structure prevents the entry of earth and sand. Suppose the first wall 16 fails to completely prevent the entry of earth and sand, and a small amount of earth and sand enters the gap between the first wall 16 and the second opposing surface 20A of the second bracket 20. Here, on the true front surface radially inside the gap between the first wall 16 and the second opposing surface 20A of the second bracket 20, the third wall 28 protruding from the second bracket 20 is located. Therefore, even if earth and sand enters radially inward from the above gap, the outer peripheral surface of the third wall 28 prevents the further entry of this earth and sand.

[0067] Now, regarding the circumferential range in which the triple labyrinth structure is formed, most of the outer peripheral surface of the second wall 27 located on the outermost side in this labyrinth structure is flush with the outer peripheral surface of the first portion 21 in the second bracket 20, as shown in FIG. 5. Therefore, as shown in FIG. 4, the outer peripheral surface of this second wall 27 is exposed to the external space. Thus, even if sediment once adheres to the outer peripheral surface of the second wall 27, this sediment quickly scatters from the outer peripheral surface of the second wall 27 due to the momentum when the excavation member 530 rotates. On the other hand, as shown in the lower part of the drawing of FIG. 3, in the circumferential range where the double labyrinth structure is formed, the outer peripheral surface of the first wall 16 located on the outermost side in this labyrinth structure is not exposed to the outside and forms the bottom of the following recess 29. That is, the outer peripheral surface of the first wall 16 demarcates the recess 29 together with the portion radially outside the first wall 16 in the first opposing surface 14A of the first bracket 10 and the portion radially outside the first wall 16 in the second opposing surface 20A of the second bracket 20. As shown in FIG. 8, the recess 29 exists over the entire circumferential region where the second wall 27 does not exist. In FIGS. 8 and 9, the region where the recess 29 exists is indicated by hatching. Sediment tends to accumulate in the recess 29. For example, as shown in FIG. 8, assume that a part of the recess 29 is located below with respect to the base rotation axis line P. And assume that sediment has accumulated in this recess 29. In FIGS. 8 and 9, the region W where sediment exists is surrounded by a dashed line. When the excavation member 530 rotates with sediment accumulated in the recess 29, the second wall 27 rotates accordingly. At this time, the tip 27A of the arc of the second wall 27 pushes the sediment accumulated in the recess 29 in the circumferential direction. The tip 27A of the second wall 27 accumulates the somewhat sparse sediment and pushes the sediment along the recess 29. As shown by the arrow W1 in FIG. 9, when the accumulated amount of the sediment pushed by the tip 27A of the second wall 27 increases, the sediment cannot fit in the recess 29 and is pushed out from the recess 29. Then, the sediment is discharged from the recess 29. In particular, in the position where the sediment in the recess 29 moves upward, etc., the sediment is easily pushed out from the recess 29 with the help of its own weight. That is, the sediment accumulated in the recess 29 is discharged so as to be scraped out by the tip 27A of the second wall 27 as the excavation member 530 rotates.

[0068] In forming a labyrinth structure between the first opposing surface 14A of the first bracket 10 and the second opposing surface 20A of the second bracket 20, it is also conceivable to make the second wall 27 annular. In this case, a triple labyrinth structure is formed over the entire circumferential direction. However, if a triple labyrinth structure is formed over the entire circumference in the circumferential direction, there are the following concerns. That is, if the labyrinth structure is triple over the entire circumference, it is difficult for earth and sand to enter inside, while it becomes difficult to discharge the earth and sand accumulated between the wall portions of the labyrinth structure to the outside. Therefore, for example, when discharging the earth and sand accumulated between the wall portions of the labyrinth structure during maintenance, it is necessary to perform a laborious operation such as cleaning after releasing the connection between the first bracket 10 and the second bracket 20.

[0069] In this regard, if a triple labyrinth structure is formed only in a part of the circumferential direction as in this embodiment, it becomes easier to discharge the earth and sand accumulated between the wall portions of the labyrinth structure. Therefore, without releasing the connection between the first bracket 10 and the second bracket 20, for example, the earth and sand accumulated between the wall portions of the labyrinth structure can be discharged by flushing with water. Therefore, the maintenance work becomes easier.

[0070] <Operation 2 of the embodiment: Stopper> When operating the excavator 500, the operator basically operates the excavation member 530 using the first mode. In the first mode, the control device 200 rotates the excavation member 530 in the first rotation direction or the second rotation direction while restricting the rotation range of the output shaft 104B of the motor 104. Along with the above restriction of the rotation range, the control device 200 rotates the excavation member 530 within a range where the second stopper 52 and the third stopper 53 protruding from the second bracket 20 do not contact the first stopper 51 protruding from the first bracket 10.

[0071] When earth and sand adhere to the first bracket 10, the second bracket 20, the bucket 531, etc. during the excavation work, the operator of the excavator 500 operates the excavation member 530 using the second mode. In the second mode, the control device 200 releases the restriction on the rotation range of the output shaft 104B of the motor 104. At the same time, in the second mode, the control device 200 makes the output torque of the motor 104 larger than that in the first mode. As shown in FIG. 7, when the control device 200 rotates the excavation member 530 in the first rotation direction in such a second mode, the second stopper 52 hits the first stopper 51 forcefully. Due to the impact at this time, earth and sand fall from the first bracket 10, the second bracket 20, and the bucket 531. Also, when the control device 200 rotates the excavation member 530 in the second rotation direction in the second mode, the third stopper 53 hits the first stopper 51 forcefully. Due to the impact at this time, earth and sand fall from the first bracket 10, the second bracket 20, and the bucket 531.

[0072] <Effects of the Embodiment> (1) In the configuration of the present embodiment, the arc-shaped second wall 27 is located on the radially outer side of the annular first wall 16. And, as described in the operation 1 of the above embodiment, in the circumferential direction range where the second wall 27 exists, the first wall 16 and the second wall 27 prevent earth and sand from entering the storage chamber 30 through the gap between the first opposing surface 14A of the first bracket 10 and the second opposing surface 20A of the second bracket 20. On the other hand, as described in the operation 1 of the above embodiment, in the circumferential direction range where the second wall 27 does not exist, as the excavation member 530 rotates, the tip 27A of the second wall 27 pushes away the earth and sand on the outer peripheral surface of the first wall 16. Therefore, even in the circumferential direction range where the second wall 27 does not exist, the entry of earth and sand into the storage chamber 30 is prevented. In the configuration of such an embodiment, it is possible to considerably suppress earth and sand from reaching the power transmission mechanism 106.

[0073] (2) In the configuration of this embodiment, in addition to the first wall 16 and the second wall 27, an annular third wall 28 is located inside the first wall 16 in the radial direction. As a result, a triple labyrinth structure and a double labyrinth structure are formed in the gap communicating the accommodation chamber 30 with the outside. By adopting a configuration combining the triple labyrinth structure and the double labyrinth structure in this way, both of the following two advantages can be enjoyed. First, since the labyrinth structure exists at various locations in the circumferential direction, it is possible to prevent earth and sand from entering the accommodation chamber 30 over the entire circumference in the circumferential direction. Second, since a part of the circumferential direction has a double labyrinth structure instead of a triple one, as described in the operation 1 of the above embodiment, the maintenance work becomes easier.

[0074] (3) In this embodiment, the second wall 27 extends over 180 degrees or more. By ensuring a long circumferential dimension of the second wall 27 in this way, the circumferential range having a triple labyrinth structure can be made as large as possible. As a result, it becomes even more difficult for earth and sand to enter the accommodation chamber 30.

[0075] (4) Earth and sand tend to adhere particularly easily around the opening 535 of the bucket 531. Considering this point, in this embodiment, as shown in FIG. 6, the second wall 27 is provided over the entire specific angular range UN from the first straight line U1 to the second straight line U2. The specific angular range UN corresponds to the portion near the opening 535 of the bucket 531 where earth and sand particularly easily adhere, among the first bracket 10 and the second bracket 20. By guarding the location where earth and sand particularly easily adhere with the second wall 27 in this way, the entry of earth and sand into the accommodation chamber 30 can be more effectively suppressed.

[0076] (5) The configuration of this embodiment includes a first stopper 51 protruding from the first bracket 10 and a second stopper 52 protruding from the second bracket 20. The presence of these first stopper 51 and second stopper 52 enables the following. That is, as described in the operation 2 of the above embodiment, by rotating the excavation member 530, the second stopper 52 is made to collide with the first stopper 51, so that the earth and sand adhering to the first bracket 10 and the second bracket 20 fall off. By this, the earth and sand can be shaken off from the first bracket 10 and the second bracket 20 themselves. As a result, almost no earth and sand adheres to the first bracket 10 and the second bracket 20. If the earth and sand adhering to the first bracket 10 and the second bracket 20 is reduced, the possibility of the earth and sand entering the storage chamber 30 is also substantially eliminated.

[0077] (6) In this embodiment, there are two stoppers, namely a second stopper 52 and a third stopper 53, on the second bracket 20. The presence of these two stoppers enables either of them to collide with the first stopper 51 when the second bracket 20 is rotated in either the forward or reverse direction. Therefore, when applying an impact to the first bracket 10 and the second bracket 20, the stopper closer to the first stopper 51 at the current rotational position of the second bracket 20 among the second stopper 52 and the third stopper 53 may be made to collide with the first stopper 51. Therefore, when causing the stoppers to collide with each other, a wide range of rotation of the second bracket 20 and thus the excavation member 530 is not required. Therefore, the power consumption of the battery 202 can be minimized.

[0078] (7) The control device 200 of this embodiment can control the motor 104 in a second mode in which the torque output by the motor 104 is made larger than in the first mode. By using this second mode, the second stopper 52 or the third stopper 53 can be made to vigorously collide with the first stopper 51. Thereby, a strong impact can be applied to the first bracket 10 and the second bracket 20. Therefore, the earth and sand can be effectively removed from the first bracket 10 and the second bracket 20.

[0079] (8) The excavator disclosed in Patent Document 1 includes a self - propelled main body, an arm extending from the main body, and an excavation bucket. The bucket is connected to the tip of the arm. The bucket is rotatable relative to the arm.

[0080] In an excavator such as that of Patent Document 1, for example, foreign matter such as earth and sand may adhere to the connection portion between the bucket and the arm. If such foreign matter is left as it is, friction may occur during operation at the connection portion or deterioration of the connection portion may be caused due to the presence of the foreign matter. Therefore, it is desirable to remove the foreign matter promptly. However, it is not practical for the operator of the excavator to get out of the driver's seat and remove the foreign matter every time it adheres. Therefore, a structure that can remove the foreign matter without the operator leaving the driver's seat is required. Note that not only the connection portion between the arm and the bucket, but also not only the excavator, but also in construction machinery, the same problem can occur if one of the two parts is rotatably connected to the other.

[0081] The configuration of this embodiment includes a first stopper 51 protruding from the first bracket 10 and a second stopper 52 protruding from the second bracket 20. The presence of these first stopper 51 and second stopper 52 enables the following. That is, as described in the operation 2 of the above - mentioned embodiment, by rotating the excavation member 530 to cause the second stopper 52 to collide with the first stopper 51, the earth and sand adhering to the first bracket 10, the second bracket 20, and further the bucket 531 fall off. By this, the earth and sand can be quickly shaken off from these.

[0082] Thus, in the configuration of the present embodiment, when removing the earth and sand from various parts of the bucket joint mechanism 510, the means of colliding the first stopper 51 and the second stopper 52 is utilized. With such a configuration, without using anything other than the shovel car 500, the earth and sand can be removed from various parts with the bucket joint mechanism 510 alone. Therefore, when the removal of earth and sand is necessary, the removal can be realized immediately on the spot. Also, at this time, the driver does not need to leave the driver's seat. Here, when the excavation member 530 is operated with the earth and sand adhering thereto, since the weight of the excavation member 530 increases, the power consumption of the battery 202 increases. As described above, in the configuration of the present embodiment, since the earth and sand can be removed on the spot when necessary, the driver can remove the earth and sand when noticing that the amount of adhered earth and sand is increasing. Therefore, in the configuration of the present embodiment, the situation of performing the excavation work with a large amount of adhered earth and sand can be avoided. With such a configuration of the present embodiment, the power consumption of the battery 202 can be suppressed.

[0083] Moreover, in the configuration of the present embodiment, when colliding the first stopper 51 and the second stopper 52 to remove the earth and sand, it is only necessary to rotate the second bracket 20 in the same manner as during the excavation work. Therefore, the driver does not need to perform complicated operations regarding the shovel car 500 when removing the earth and sand, and only needs to perform the same operations as during the excavation work. Thus, in the configuration of the present embodiment, no burden is imposed on the driver when removing the earth and sand.

[0084] Furthermore, in the configuration of the present embodiment, as a configuration for removing the earth and sand from various parts of the bucket joint mechanism 510, a very simple structure in which only protrusions are provided on the first bracket 10 and the second bracket 20 respectively is adopted. Therefore, the configuration of the entire bucket joint mechanism 51 does not become complicated, and neither the enlargement of parts nor the increase in the number of parts is caused.

[0085] In the case of a construction machine having a bucket 531, during the operation of excavating earth and sand with the bucket 531, it is inevitable that a large amount of earth and sand adheres to the periphery of the bucket 531. In such a construction machine, it is particularly effective to adopt the configuration regarding each of the above stoppers.

[0086] (10) As shown in FIG. 7, in the present embodiment, when the second stopper 52 contacts the first stopper 51, a virtual half-line U3 is located in the opening direction V as viewed from the opening 535 of the bucket 531. Here, during the excavation work, in consideration of the direction of the arm 520, the virtual half-line U3 often works in a state of extending substantially vertically. Therefore, due to the positional relationship of the virtual half-line U3 with respect to the above-described opening direction V, at the position where the second stopper 52 contacts the first stopper 51, the opening 535 of the bucket 531 faces downward. Therefore, it is easy to remove the earth and sand inside the bucket 531 when the second stopper 52 collides with the first stopper 51.

[0087] <Modified Example> The above embodiment can be implemented with the following modifications. The above embodiment and the following modified examples can be implemented in combination with each other within a technically non-contradictory range.

[0088] · In the above embodiment, earth and sand are handled as an example of foreign matter. However, the foreign matter may not be earth and sand. For foreign matter other than earth and sand, each component of the bucket joint mechanism 510 functions in the same manner as in the above embodiment.

[0089] · The configuration of the power transmission mechanism 106 is not limited to the example of the above embodiment. The power transmission mechanism 106 only needs to be able to transmit the power for rotating the second bracket 20 to the second bracket 20. ·The power source is not limited to the examples of the above embodiments. The power source only needs to be able to supply power to the power transmission mechanism 106. For example, the power source may be a hydraulic motor. The power source is not limited to those that supply the power of rotational motion to the power transmission mechanism 106. For example, it may be one that supplies the power of linear motion to the power transmission mechanism 106. In this case, the power transmission mechanism 106 may convert the linear motion into rotational motion and transmit it to the second bracket 20.

[0090] ·Regarding the way of controlling the power source, the way of setting the torque in the first mode is not limited to the examples of the above embodiments. In the first mode, it is only necessary that the torque output by the motor 104 can be limited to less than the specified value. For example, the magnitude of the torque available in the first mode may be switched continuously rather than stepwise. There may be only one magnitude of torque available in the first mode.

[0091] ·The way of setting the torque in the second mode is not limited to the examples of the above embodiments. In the second mode, it is only necessary that the torque output by the motor 104 can be allowed to be equal to or greater than the specified value. The magnitude of the torque output by the motor 104 within the second mode may be switched stepwise or continuously.

[0092] ·The way of determining the specified value is not limited to the examples of the above embodiments. The specified value may be appropriately set as an appropriate value as the boundary value for switching between the torque required during the excavation work and the torque required for removing foreign objects.

[0093] ·The specified value may vary depending on the type of component employed as the power source. Also, the variable indicating the power of the power source may vary depending on the type of component employed as the power source. Furthermore, the way of control by the control device 200 may vary depending on the type of component employed as the power source. No matter what kind of power source is used, in the first mode, the power output by the power source is limited to less than the specified value, while in the second mode, the configuration should be such that the power output by the power source is allowed to be equal to or greater than the specified value.

[0094] ·It is not essential that the control device 200 is configured to be able to switch between the first mode and the second mode. For example, when the motor 104 is adopted as a power source as in the above embodiment, the second mode may be abolished, and the rotation range of the output shaft 104B of the motor 104 may be unrestricted in the first mode for excavation work. Even though the torque available in the first mode is relatively small, if the second stopper 52 or the third stopper 53 collides with the first stopper 51, an impact will occur at least on the first bracket 10 and the second bracket 20, so that foreign matter can be removed therefrom. Also, for example, as a control mode used by the control device 200, a configuration may be adopted in which the rotation range of the output shaft 104B of the motor 104 is always unrestricted and the torque output by the motor 104 is not restricted. Even in this case, if the operator of the excavator 500 can control the rotation range of the output shaft 104B of the motor 104 and the torque output by the motor 104 by his / her own operation, the operator can do the following. That is, the operator can rotate the excavation member 530 to a position where the second stopper 52 or the third stopper 53 collides with the first stopper 51 as needed, or stop the rotation of the excavation member 530 before the second stopper 52 or the third stopper 53 collides with the first stopper 51.

[0095] ·The form of the switching signal is not limited to the example of the above embodiment. For example, the switching signal may be a signal indicating that the motor 104 is controlled in the first mode instead of a signal indicating that the motor 104 is controlled in the second mode as in the above embodiment. There may be a plurality of switching signals such as a first signal indicating that the motor 104 is controlled in the first mode and a second signal indicating that the motor 104 is controlled in the second mode. Also, the switching signal does not have to be continuously output over the entire period during which the specified control mode is being used, as in the above embodiment, and may be output only at the timing of switching between the first mode and the second mode. As long as the control device 200 can determine a signal for switching between the first mode and the second mode, the form of the switching signal does not matter. The processing content of the control device 200 may be set according to the form of the switching signal.

[0096] · The mode of the operating device that outputs the switching signal is not limited to the examples of the above embodiments. For example, when adopting a configuration using a plurality of switching signals as in the above modification example, these two signals may be output by one operating device, or operating devices corresponding to individual signals may be provided separately. As long as the switching signal can be output, the mode of the operating device is not limited.

[0097] · The shape of the first stopper 51 is not limited to the examples of the above embodiments. The first stopper 51 may be, for example, columnar. The first stopper 51 only needs to have a shape that can contact the second stopper 52.

[0098] · The arrangement of the first stopper 51 is not limited to the examples of the above embodiments. The first stopper 51 only needs to be arranged at a position where it can contact the second stopper 52. · The shape of the second stopper 52 is not limited to the examples of the above embodiments. The second stopper 52 may be, for example, rectangular parallelepiped-shaped. The second stopper 52 only needs to have a shape that can contact the first stopper 51.

[0099] · The arrangement of the second stopper 52 is not limited to the examples of the above embodiments. The second stopper 52 only needs to be arranged at a position where it can contact the first stopper 51 when the second bracket 20 rotates within a predetermined range from the reference position. The predetermined range is not limited to the examples of the above embodiments. Furthermore, it is not essential that the second stopper 52 is arranged to satisfy the position conditions of the above embodiments related to the opening direction V and the virtual half-line U3. As long as the second stopper 52 exists at a position where it can contact the first stopper 51, foreign objects can be removed by the impact when the second stopper 52 collides with the first stopper 51.

[0100] · Similar to the second stopper 52, the shape and arrangement of the third stopper 53 are not limited to the examples of the above embodiments. The third stopper 53 may be arranged at a position asymmetric to the second stopper 52. The shape of the third stopper 53 may also be different from that of the second stopper 52.

[0101] · The third stopper 53 may be abolished. · The method of determining the reference position is not limited to the example of the above embodiment. The reference position may be appropriately determined in consideration of the rotation range of the excavation member 530 required during the excavation work, the orientation of the opening 535 of the bucket 531, and the like.

[0102] · From the perspective of suppressing foreign matter from reaching the power transmission mechanism 106, the first stopper 51 and the second stopper 52 are not essential. Even if the first stopper 51 and the second stopper 52 are absent, if the first wall 16 and the second wall 27 are present, the entry of foreign matter into the power transmission mechanism 106 can be suppressed.

[0103] · The dimension of the second wall 27 in the circumferential direction is not limited to the example of the above embodiment. The dimension may be longer or shorter than the example of the above embodiment. The dimension may also be less than 180 degrees. Regardless of the length or shortness of the dimension, if the second wall 27 is present, this second wall 27 functions to prevent the entry of foreign matter from the outside.

[0104] · The position of the second wall 27 in the circumferential direction is not limited to the example of the above embodiment. The second wall 27 may be present only in a part rather than the entire specific angular range UN, or the second wall 27 may not be present at all in the specific angular range UN. It is sufficient that the second wall 27 is present somewhere in the circumferential direction.

[0105] · A plurality of second walls 27 may be present. That is, arc-shaped second walls 27 may be provided at separate locations in the circumferential direction, respectively. · The dimension of the second wall 27 in the axial direction is not limited to the example of the above embodiment. It is sufficient that the dimension of the second wall 27 in the axial direction is set such that at least a part of the second wall 27 and the first wall 16 overlap in the axial direction. The dimension of the second wall 27 in the axial direction may vary depending on the circumferential position. Similarly, the dimension of the first wall 16 in the axial direction is not limited to the example of the above embodiment. As described above, it is sufficient that at least a part of the second wall 27 and the first wall 16 overlap in the axial direction.

[0106] · It is not essential to make the third wall 28 annular. That is, the third wall 28 may be arc-shaped. · Similar to the second wall 27, the axial dimension of the third wall 28 is not limited to the example of the above embodiment. The axial dimension of the third wall 28 may be set such that at least a part of the third wall 28 and the first wall 16 overlap in the axial direction.

[0107] · The third wall 28 may be omitted. · The shapes of the first bracket 10 and the second bracket 20 are not limited to the example of the above embodiment. Each bracket may be configured to be able to provide each wall portion necessary for forming the labyrinth structure, each stopper necessary for removing foreign matter, etc., while realizing the original functions such as holding the power transmission mechanism 106 and transmitting the power from the power transmission mechanism 106 to the bucket 531.

[0108] · The bracket that protrudes the first wall 16 and the bracket that protrudes the second wall 27 may be interchanged. That is, the first wall 16 may protrude from the second bracket 20, and the second wall 27 may protrude from the first bracket 10. In this case, the excavation member 530 constitutes the first member, and the arm 520 constitutes the second member. Even when the bracket that protrudes the first wall 16 and the bracket that protrudes the second wall 27 are interchanged, the first wall 16 may be made annular, and the arc-shaped second wall 27 may be arranged outside the first wall 16 in the radial direction. Here, when the excavation member 530 and thus the second bracket 20 rotate, it means that the first bracket 10 rotates as seen from the second bracket 20. That is, if one rotates with respect to the other, it can be said that the power transmission mechanism 106 gives the rotational power to both of them. Therefore, for this type of configuration, even if the first member and the second member are interchanged, the relationship that the power transmission mechanism 106 transmits the rotational power to the second member is satisfied.

[0109] · The locations to which the first wall 16 and the second wall 27 are applied are not limited to the connection location between the excavation member 530 and the arm 520. The above-mentioned target location may be, for example, the connection location between the arm 520 and the boom 504. As long as the two facing members are rotatably connected to each other, a configuration similar to the above-described embodiment in which the first wall and the second wall protrude from these two members can be realized. When the first wall 16 and the second wall 27 are provided at locations other than the connection location between the excavation member 530 and the arm 520, further, a third wall 28 may be provided, or a first stopper 51 and a second stopper 52 may be provided.

[0110] · The construction machine to which the first wall 16 and the second wall 27 are applied is not limited to the excavator 500. Even for a construction machine other than the excavator 500, as long as there is a location where two facing members are rotatably connected to each other as described above, the first wall 16 and the second wall 27 can be applied to such a location.

[0111] · From the perspective of removing foreign matter from the first bracket 10 and the second bracket 20, the first wall 16 and the second wall 27 are not essential. Even without the first wall 16 and the second wall 27, if there are a first stopper 51 and a second stopper 52, foreign matter can be removed from the first bracket 10 and the second bracket 20.

[0112] · Including the case of abolishing the first wall 16 and the second wall 27, the locations to which the first stopper 51 and the second stopper 52 are applied are not limited to the connection location between the excavation member 530 and the arm 520. The above-mentioned target location may be, for example, the connection location between the arm 520 and the boom 504. As long as there are two members where one rotates relative to the other, a configuration similar to the above-described embodiment in which the first stopper 51 protrudes from one of these two members and the second stopper 52 protrudes from the other can be realized. Depending on the location to which the first stopper 51 and the second stopper 52 are applied, the two members may not be connected by the power transmission mechanism 106, or further, the power transmission mechanism 106 may not exist around the two members. Even in such cases, if the two stoppers are made to collide, the effect of removing foreign matter by the impact can be enjoyed. That is, it is not essential for the power transmission mechanism 106 to exist at the location to which the first stopper 51 and the second stopper 52 are applied.

[0113] · The construction machine to which the first stopper 51 and the second stopper 52 are applied is not limited to the excavator 500. Even for construction machines other than the excavator 500, as long as there are locations where two members rotate relative to each other as described above, the first stopper 51 and the second stopper 52 can be applied to such locations.

[0114] · In the above-described embodiment, those composed of a plurality of objects may integrate the plurality of objects, and conversely, those composed of a single object can be divided into a plurality of objects. Whether integrated or not, it may be configured so that the object of the invention can be achieved.

[0115] · In the above-described embodiment, those in which a plurality of functions are provided dispersedly may provide some or all of the plurality of functions in an aggregated manner, and conversely, those in which a plurality of functions are provided in an aggregated manner can be provided so that some or all of the plurality of functions are dispersed. Whether the functions are aggregated or dispersed, it may be configured so that the object of the invention can be achieved.

Explanation of Reference Numerals

[0116] P... Base rotation axis 10... First bracket 14A... First opposing surface 16... First wall 20... Second bracket 20A... Second opposing surface 27... Second wall 28... Third wall 51... First stopper 52... Second stopper 53... Third stopper 106... Power transmission mechanism 200... Control device 500... Excavator 531... Bucket 535... Opening

Claims

1. a first member having a first opposing surface; a second member rotatable with respect to the first member about a rotation axis and having a second opposing surface opposing the first opposing surface; a power transmission mechanism for transmitting rotational power to the second member; an annular first wall protruding from the first opposing surface and centered on the rotation axis; an arcuate second wall protruding from the second opposing surface and centered on the rotation axis, and comprising: the power transmission mechanism is located inside the first wall in the radial direction centered on the rotation axis; the second wall is located outside the first wall in the radial direction and at least partially overlaps the first wall in the direction along the rotation axis a joint mechanism of a construction machine.

2. an annular third wall protruding from the second opposing surface and centered on the rotation axis; the third wall is located between the power transmission mechanism and the first wall in the radial direction and at least partially overlaps the first wall in the direction along the rotation axis The joint mechanism of a construction machine according to claim 1.

3. the second wall extends over 180 degrees or more about the rotation axis The joint mechanism of a construction machine according to claim 1.

4. the second member has a bucket having an opening; the direction perpendicular to the opening surface of the bucket and from the inside to the outside of the bucket through the opening surface is defined as the opening direction; when viewed in the direction along the rotation axis, when a virtual straight line connecting the shortest distance between the rotation axis and the opening surface is defined as a first straight line and a virtual straight line extending from the rotation axis in the opening direction is defined as a second straight line; the second wall extends over the entire angular range from the first straight line to the second straight line in the circumferential direction centered on the rotation axis and on the side where the opening surface is open. The joint mechanism of a construction machine according to claim 1.

5. a first stopper protruding from the first member; a second stopper protruding from the second member and contacting the first stopper when the second member rotates a predetermined range in a first rotation direction from a predetermined reference position; The joint mechanism of a construction machine according to claim 1.

6. a third stopper protruding from the second member and contacting the first stopper when the second member rotates the predetermined range in a direction opposite to the first rotation direction from the reference position The joint mechanism of a construction machine according to claim 5.

7. A power source that supplies power to the power transmission mechanism, A control device that controls the power source, and The control device Is capable of receiving a switching signal from outside the control device, Based on the switching signal, a first mode that limits the power output by the power source to less than a specified value and a second mode that allows the power output by the power source to be equal to or greater than the specified value are switched. The joint mechanism of a construction machine according to claim 5.

8. A first member, A second member rotatable with respect to the first member, A first stopper protruding from the first member, A second stopper protruding from the second member and contacting the first stopper when the second member rotates within a predetermined range from a predetermined reference position. The joint mechanism of a construction machine.

9. A power transmission mechanism that connects the first member and the second member so as to be relatively rotatable and transmits rotational power to the second member, The second member has a bucket having an opening. The joint mechanism of a construction machine according to claim 8.

10. The second member has a bucket having an opening, The direction perpendicular to the opening surface of the bucket and facing from the inside to the outside of the bucket through the opening surface is defined as the opening direction, When viewed in the direction along the rotation axis of the second member, At the position where the second stopper contacts the first stopper, a virtual half-line extending in the direction opposite to the first stopper starting from the rotation axis is located in the opening direction when viewed from the opening surface. The joint mechanism of a construction machine according to claim 8.

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