Drive transmission device

Abstract

To provide a drive transmission device and a construction machine capable of being miniaturized while relieving impact load from the external.SOLUTION: A drive transmission device 1 includes: an arm 109 having a motor which generates torque; a speed reduction portion 3 disposed on the arm 109 and having a carrier 14 reducing a speed of rotation of the motor and outputting the same; a bucket 110 having a bracket through hole 115 to which a reamer bolt 80 is inserted so that it is fixed to the carrier 14 by the reamer bolt 80 inserted to the bracket through hole 115; and a resin bush 82 disposed between an inner face of the bracket through hole 115 and an outer face of the reamer bolt 80. Mechanical strength of the resin bush 82 is lower than mechanical strength of the bucket 110 and mechanical strength of the reamer bolt 80.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a drive transmission device. Place Regarding. [Background technology]

[0002] For example, a joint mechanism of a robot or the like is provided with a gear mechanism consisting of multiple gears that are driven by the power of a motor or the like. Various technologies have been proposed to reduce the transmission of external impact loads to the gear mechanism and extend the product life. For example, a technology has been proposed that provides an elastic member with an end connected to each of two members (links) to which meshed gears are fixed, and a stopper pin provided on one of the two members. The other of the two members is pressed against the stopper pin by the elastic member.

[0003] With this configuration, the two members usually move together as one unit because the other of the two members is pressed against the stopper pin. In contrast, when an external impact load is applied to one of the two members, the two members move relative to each other against the spring force of the elastic member. This can reduce the impact load applied to one of the two members from the outside from being transmitted to the other member. As a result, the impact load transmitted to the gear mechanism can be reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-104070 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, it is necessary to provide the elastic member and the stopper pin in a location separate from the gear mechanism. In other words, it is difficult to incorporate the elastic member and the stopper pin into the gear mechanism. This makes it difficult to reduce the size of the entire device.

[0006] The present invention provides a drive transmission device that can be made compact while absorbing external impact loads. Place to provide. [Means for solving the problem]

[0007] A drive transmission device according to one embodiment of the present invention comprises a first member having a drive source that generates a rotational force, a speed change section provided on the first member and having an output section that changes the rotation of the drive source and outputs it, a second member having a through hole into which a fixed member is inserted and fixed to the output section by the fixed member inserted into the through hole, and an interference member provided between an inner surface of the through hole and an outer surface of the fixed member, wherein the mechanical strength of the interference member is lower than the mechanical strength of the second member and the mechanical strength of the fixed member.

[0008] With this configuration, the interference member can absorb the external impact load applied to the second member, and can reduce the transmission of this impact load to the transmission unit. Moreover, the interference member is provided between the outer surface of the fixed member fixed to the output unit and the inner surface of the through hole formed in the second member. Therefore, no space is required to provide the interference member at a location separated from the transmission unit, and the interference member can be incorporated as part of the transmission unit. Therefore, the drive transmission device can be made smaller while reducing the external impact load.

[0009] In the aforementioned configuration, the interference member may be made of resin.

[0010] In the above configuration, the fixing member may have a pin portion inserted into the through hole and a male threaded portion integrally molded coaxially with one axial end of the pin portion, and the output portion may have a female threaded portion into which the male threaded portion is screwed, and a fitting portion into which the one axial end of the pin portion is fitted.

[0011] In the above configuration, the fixing member may have a bolt inserted into the through hole and a hollow pin fitted between the bolt and the interference member, and the output portion may have a female threaded portion into which the bolt is fastened and a fitting portion into which one axial end of the hollow pin is fitted.

[0012] In the above configuration, a pressing plate may be provided on the opposite side of the second member from the output portion, covering the interference member, and the pressing plate may have a plate through hole into which the fixing member is inserted.

[0013] In the above configuration, the transmission unit includes a case and the output unit which rotate relatively around the same first rotational axis, at least one crankshaft which is arranged between the case and the output unit and rotates around a second rotational axis along the first rotational axis in response to rotation of the drive source, and an external teeth member having external teeth which oscillates and rotates around the first rotational axis by the crankshaft, wherein the case has internal teeth which mesh with the external teeth and is fixed to the first member, and the output unit rotatably supports the crankshaft and is rotatably supported on the case via a bearing, and may rotate at a slower speed than the rotation of the crankshaft.

[0014] a second member having a through hole into which a fixing member is inserted and fixed to the output portion by the fixing member inserted into the through hole; an interference member formed of a resin having a mechanical strength lower than that of the second member and that of the fixing member and provided between an inner surface of the through hole and an outer surface of the fixing member; and a pressing plate provided on the opposite side of the output portion across the second member, having a plate through hole into which the fixing member is inserted and covering the interference member, the pressing plate having a pin portion inserted into the through hole and a pressing member extending coaxially from the pin portion at one axial end of the pin portion. and a male threaded portion integrally molded onto the case, the output portion has a female threaded portion into which the male threaded portion is fastened, and a fitting portion into which the axial one end of the pin portion is fitted, the transmission portion comprises a case and the output portion which rotate relatively about the same first rotation axis, at least one crankshaft which is disposed between the case and the output portion and rotates about a second rotation axis along the first rotation axis in response to rotation of the drive source, and an external teeth member which has external teeth and which oscillates and rotates about the first rotation axis by the crankshaft, the case has internal teeth which mesh with the external teeth and is fixed to the first member, the output portion rotatably supports the crankshaft and is rotatably supported on the case via a bearing, and rotates at a slower speed than the rotation of the crankshaft.

[0015] With this configuration, the interference member can absorb the external impact load applied to the second member, and can reduce the transmission of this impact load to the transmission unit. Moreover, the interference member is provided between the outer surface of the fixed member fixed to the output unit and the inner surface of the through hole formed in the second member. Therefore, no space is required to provide the interference member at a location separated from the transmission unit, and the interference member can be incorporated as part of the transmission unit. Therefore, the drive transmission device can be made smaller while reducing the external impact load. Furthermore, since the interference member is made of resin, it can be easily formed. Furthermore, the fixing member has a pin portion inserted into the through hole and a male screw portion integrally molded coaxially with the pin portion at one axial end of the pin portion. The output portion has a female screw portion into which the male screw portion is fastened and a hole portion into which the axial end of the pin portion is fitted. Therefore, the fixing member can be firmly fixed to the output portion. Also, the rotation of the output portion can be reliably transmitted to the second member via the fixing member. In addition, the pressing plate can prevent the interference member, which has a weak mechanical strength, from being exposed to the outside and can prevent the interference member from coming into contact with foreign matter such as sand, thereby extending the product life of the interference member. Furthermore, the transmission unit can provide high output with a high reduction ratio. This allows the drive transmission device to be made smaller while increasing the drive torque of the first and second members. In addition, the simultaneous meshing rate of the gears that make up the transmission unit can be increased, improving the drive transmission device's resistance to overloads and shock loads.

[0016] A drive transmission device according to another aspect of the present invention includes a first member having a drive source that generates a rotational force, a speed change section provided on the first member and having an output section that changes the speed of rotation of the drive source and outputs the rotation, a second member having a through hole into which a fixing member is inserted and fixed to the output section by the fixing member inserted into the through hole, an interference member formed of a resin having a mechanical strength lower than that of the second member and that of the fixing member and provided between an inner surface of the through hole and an outer surface of the fixing member, and a pressing plate provided on the opposite side of the second member to the output section, having a plate through hole into which the fixing member is inserted and covering the interference member, wherein the fixing member is a bolt inserted into the through hole, and a pressing plate fitted between the bolt and the interference member. and a hollow pin that is mated with the bolt, the output section has a female threaded section into which the bolt is fastened and a fitting section into which one axial end of the hollow pin is fitted, the transmission section comprises a case and the output section which rotate relatively about the same first rotation axis, at least one crankshaft arranged between the case and the output section and which rotates about a second rotation axis along the first rotation axis in response to rotation of the drive source, and an external teeth member having external teeth that oscillates and rotates about the first rotation axis by the crankshaft, the case has internal teeth that mesh with the external teeth and is fixed to the first member, the output section rotatably supports the crankshaft and is rotatably supported on the case via a bearing and rotates at a slower speed than the rotation of the crankshaft.

[0017] With this configuration, the interference member can absorb the external impact load applied to the second member, and can reduce the transmission of this impact load to the transmission unit. Moreover, the interference member is provided between the outer surface of the fixed member fixed to the output unit and the inner surface of the through hole formed in the second member. Therefore, no space is required to provide the interference member at a location separated from the transmission unit, and the interference member can be incorporated as part of the transmission unit. Therefore, the drive transmission device can be made smaller while reducing the external impact load. Furthermore, since the interference member is made of resin, it can be easily formed. Furthermore, the fixing member has a pin portion inserted into the through hole and a male screw portion integrally molded coaxially with the pin portion at one axial end of the pin portion. The output portion has a female screw portion into which the male screw portion is fastened and a hole portion into which the axial end of the pin portion is fitted. Therefore, the fixing member can be firmly fixed to the output portion. Also, the rotation of the output portion can be reliably transmitted to the second member via the fixing member. In addition, the pressing plate can prevent the interference member, which has a weak mechanical strength, from being exposed to the outside and can prevent the interference member from coming into contact with foreign matter such as sand, thereby extending the product life of the interference member. Furthermore, the transmission unit can provide high output with a high reduction ratio. This allows the drive transmission device to be made smaller while increasing the drive torque of the first and second members. In addition, the simultaneous meshing rate of the gears that make up the transmission unit can be increased, improving the drive transmission device's resistance to overloads and shock loads.

[0018] A construction machine according to another aspect of the present invention comprises a vehicle body, a first member provided on the vehicle body and having a driving source that generates a rotational force, a speed change section provided on the first member and having an output section that changes the speed of the rotation of the driving source and outputs it, a second member having a through hole into which a fixing member is inserted and fixed to the output section by the fixing member inserted into the through hole, and an interference member provided between the inner surface of the through hole and the outer surface of the fixing member, wherein the mechanical strength of the interference member is lower than the mechanical strength of the second member and the mechanical strength of the fixing member.

[0019] With this configuration, the interference member can absorb the external impact load applied to the second member, and can reduce the transmission of this impact load to the transmission unit. Moreover, the interference member is provided between the outer surface of the fixed member fixed to the output unit and the inner surface of the through hole formed in the second member. Therefore, no space is required to provide the interference member at a location separated from the transmission unit, and the interference member can be incorporated as part of the transmission unit. This allows the construction machine as a whole to be made smaller while reducing the impact load from the outside. Effect of the Invention

[0020] The drive transmission device and construction machine described above do not require space for providing an interference member at a location separated from the speed change unit, and the interference member can be incorporated as part of the speed change unit, which allows for size reduction while mitigating external impact loads. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic configuration diagram of a shovel according to an embodiment of the present invention, as viewed from the side. [Diagram 2] FIG. 2 is a schematic configuration diagram showing details of a connection portion between an arm and a bucket in the first embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic configuration diagram of a speed reducer unit according to the first embodiment of the present invention. [Figure 4] Detailed view of part A in Figure 2. [Diagram 5] 5 is a cross-sectional view taken along line BB in FIG. 4 . [Figure 6] 13 is a diagram showing a fixing structure between a speed reducer and a bucket mounting bracket in a second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings.

[0023] <Shovel> FIG. 1 is a schematic diagram of a shovel 100 according to an embodiment of a construction machine of the present invention, viewed from the side. In the following description, the front, which an operator (not shown) who operates the shovel 100 faces, is simply referred to as the front. The side horizontally opposite the front is referred to as the rear. The up-down direction when the shovel 100 is placed on the road surface is simply referred to as the up-down direction. The direction perpendicular to the fore-aft and up-down directions is referred to as the vehicle width direction. FIG. 1 shows the shovel 100 as viewed from the vehicle width direction.

[0024] As shown in Fig. 1, the excavator 100 includes a self-propelled running body 101, a rotating body 103 that is provided on the upper part of the running body 101 via a turning mechanism 102 and turns relative to the running body 101, and an action unit 104 that is provided on the turning body 103. The running body 101 and the turning mechanism 102 are driven by, for example, an electric motor with a reduction gear (not shown). The running body 101 includes, for example, two caterpillars 105 that are aligned in the vehicle width direction. However, the present invention is not limited to this, and wheels or the like may be used instead of the caterpillars 105.

[0025] The action unit 104 includes a boom 108 and an arm 109 that are long in the front-rear direction, and a bucket 110. The boom 108, the arm 109, and the bucket 110 are rotatably connected to each other via a drive transmission device 1. Specifically, one longitudinal end of the boom 108 (in FIG. 1, the longitudinal end of the boom 108 and the drive transmission device 1 provided at the longitudinal end are not shown) is rotatably connected to the revolving body 103 via the drive transmission device 1. One longitudinal end 109a of the arm 109 is rotatably connected to the other longitudinal end 108a of the boom 108 via the drive transmission device 1. The bucket 110 is rotatably connected to the other longitudinal end 109b of the arm 109 via the drive transmission device 1. The drive transmission devices 1 provided in each section have the same configuration. Therefore, in the following description, only the drive transmission device 1 that connects the bucket 110 to the other longitudinal end 109b of the arm 109 will be described, and descriptions of the other drive transmission devices 1 will be omitted.

[0026] Fig. 2 is a schematic diagram showing the details of a connection portion between the arm 109 and the bucket 110. In Fig. 2, for ease of understanding, the arm 109 and the bucket 110 are indicated by two-dot chain lines. 2, arm 109 has a built-in motor (an example of a drive source in the claims) 120, and transmits the rotational force of motor 120 to bucket 110 via drive transmission device 1. In other words, arm 109 is an example of a first member in the claims. Bucket 110 is an example of a second member in the claims. The motor 120 is disposed such that a motor shaft 120a that rotates about a first rotation axis C1 faces the bucket 110. The first rotation axis C1 of the motor shaft 120a and the longitudinal direction of the arm 109 coincide with each other.

[0027] [First embodiment] <Drive transmission device> The drive transmission device 1 comprises a reduction gear unit 3 attached to the other longitudinal end 109b of the arm 109, a reamer bolt (an example of a fixing member in the claims) 80 that fixes the reduction gear unit 3 and the bucket 110, a resin bush (an example of an interference member in the claims) 6 provided between the outer peripheral surface of the reamer bolt 80 and the bucket 110, and a pressing plate 90 that presses the resin bush 6 from the side opposite the reduction gear unit 3.

[0028] <Deceleration part> FIG. 3 is a schematic diagram of the speed reducer unit 3. As shown in FIG. As shown in Figures 2 and 3, the reduction gear unit 3 includes a cylindrical case 11 attached to one side surface 109c in the short direction of the arm 109, a carrier 14 arranged radially inside the case 11, and a reduction output unit 18 that rotates the carrier 14 at a rotational speed that is reduced by a fixed ratio relative to the rotational speed of the motor shaft 120a.

[0029] <Case> The case 11 is formed in a cylindrical shape. The central axis Cc of the case 11 coincides with a second rotation axis C2 (an example of a first rotation axis in the claims) of the bucket 110 relative to the arm 109. In the following description, a direction parallel to the second rotation axis C2 may be referred to as an axial direction, a direction around the second rotation axis C2 may be referred to as a circumferential direction, and a direction perpendicular to the axial direction and the circumferential direction may be referred to as a radial direction.

[0030] An outer flange portion 11a that protrudes radially outward is integrally formed on the outer peripheral surface of the case 11. The outer flange portion 11a has a rectangular cross section along the axial direction. One side surface 109c of an arm 109 is fastened and fixed to the outer flange portion 11a by a bolt 5. The case 11 has an inner circumferential surface provided with internal teeth 24. The internal teeth 24 are pin-shaped (cylindrical) teeth provided on the inner circumferential surface of the case 11. A plurality of the internal teeth 24 are arranged at equal intervals in the circumferential direction.

[0031] <Career> The carrier 14 is rotatably supported in the case 11 by a pair of main bearings 26 (one example of the bearings in the claims) spaced apart in the axial direction. The main bearings 26 are, for example, angular contact ball bearings. The carrier 14 is arranged coaxially with the case 11 and the second rotation axis C2.

[0032] The carrier 14 comprises an end plate portion 30 arranged on the arm 109 side in the axial direction, a base portion 32 arranged on the opposite side of the arm 109, and three cylindrical pillar portions 33 molded integrally with the base portion 32 and protruding from the base portion 32 toward the end plate portion 30. The column portions 33 are arranged at equal intervals in the circumferential direction. The end plate portion 30 is arranged at the tip 33a of the column portion 33. The end plate portion 30 is fastened and fixed to the column portion 33 by a bolt 34. In this state, a space having a constant width in the axial direction is formed between the base portion 32 and the end plate portion 30.

[0033] A pin 36 for positioning the end plate portion 30 relative to the base plate portion 32 is provided slightly radially inward of the bolt 34 of the column portion 33. The pin 36 is disposed so as to straddle the column portion 33 and the end plate portion 30. It is to be noted that the pillar portion 33 does not have to be formed integrally with the base plate portion 32. In this case, the pillar portion 33 is fastened to the base plate portion 32. The pillar portion 33 is not limited to being cylindrical. It is sufficient that the pillar portion 33 forms a space having a certain width in the axial direction between the base plate portion 32 and the end plate portion 30.

[0034] Further, a plurality of through holes 30c, 32b (for example, three in this embodiment) into which a crankshaft 46, which will be described later, of the reduction output section 18 is inserted are formed in the end plate portion 30 and the base plate portion 32. The through holes 30c, 32b are disposed at equal intervals in the circumferential direction.

[0035] <Deceleration output section> The reduction output unit 18 includes a plurality of (for example, three in this embodiment) transmission gears 44 to which the rotation of the motor shaft 120a of the motor 120 is transmitted, a plurality of (for example, three in this embodiment) crankshafts 46 having one end fixed to the transmission gears 44, and a first external gear (an example of the external gear member in the claims) 48a and a second external gear (an example of the external gear member in the claims) 48b that oscillate and rotate with the rotation of the crankshafts 46. The rotation of the motor shaft 120a is transmitted to the transmission gear 44 via, for example, a bevel gear or the like (not shown).

[0036] Since the transmission gear 44 is fixed to one end of the crankshaft 46 , the rotation of the first operating output shaft 76 a is transmitted to the crankshaft 46 via the transmission gear 44 . The crankshaft 46 is disposed along the axial direction. That is, the crankshaft 46 rotates about a crank rotation axis C4 (an example of another rotation axis in the claims) parallel to the second rotation axis C2. The crankshaft 46 is rotatably supported by the end plate portion 30 via a first crank bearing 51. The crankshaft 46 is rotatably supported by the base plate portion 32 via a second crank bearing 52. The first crank bearing 51 and the second crank bearing 52 are, for example, tapered roller bearings.

[0037] A first eccentric portion 46a and a second eccentric portion 46b are formed in the axial center of the crankshaft 46, and are eccentric from the axial center of the crankshaft 46. The first eccentric portion 46a and the second eccentric portion 46b are disposed adjacent to each other in the axial direction between the first crank bearing 51 and the second crank bearing 52. The first eccentric portion 46a is adjacent to the first crank bearing 51. The second eccentric portion 46b is adjacent to the second crank bearing 52. The first eccentric portion 46a and the second eccentric portion 46b are also out of phase with each other. Such a crankshaft 46 is inserted into each of the through holes 30c, 32b of the end plate portion 30 and the base plate portion 32. That is, the crankshafts 46 are also disposed at equal intervals in the circumferential direction, similar to the through holes 30c, 32b.

[0038] A first roller bearing 55a is attached to the first eccentric portion 46a of the crankshaft 46. A second roller bearing 55b is attached to the second eccentric portion 46b. The first roller bearing 55a is, for example, a cylindrical roller bearing. The first roller bearing 55a has a plurality of rollers 56 and a cage 57 that holds the plurality of rollers 56. The second roller bearing 55b has a similar configuration to the first roller bearing 55a, and therefore a detailed description thereof will be omitted. The first external gear 48a and the second external gear 48b are oscillated and rotated via the roller bearings 55a and 55b in association with the rotation of the crankshaft 46.

[0039] The first external gear 48a and the second external gear 48b are disposed in the space between the base plate portion 32 and the end plate portion 30 of the carrier 14. The first external gear 48a and the second external gear 48b have external teeth 49a, 49b that mesh with the internal teeth 24 of the case 11. The first external gear 48a and the second external gear 48b are formed with a first through hole 48c into which the column portion 33 is inserted and a second through hole 48d into which the eccentric portions 46a, 46b of the crankshaft 46 are inserted.

[0040] The first eccentric portion 46a of the crankshaft 46 and the first roller bearing 55a are inserted into the second through hole 48d of the first external gear 48a. The second eccentric portion 46b of the crankshaft 46 and the second roller bearing 55b are inserted into the second through hole 48d of the second external gear 48b. As a result, as the first eccentric portion 46a and the second eccentric portion 46b oscillate and rotate due to the rotation of the crankshaft 46, the first external gear 48a and the second external gear 48b oscillate and rotate while meshing with the internal teeth 24 of the case 11.

[0041] <Fixing structure between reduction gear section and bucket> Fig. 4 is a detailed view of part A in Fig. 2. Fig. 5 is a cross-sectional view taken along line BB in Fig. 4. 2, 4, and 5, the bucket 110 is fastened to the base plate portion 32 of the carrier 14 by a pressure plate 90 and a pressure plate mounting bolt 91. In addition to the pressure plate mounting bolt 91, the base plate portion 32 of the carrier 14 and the bucket 110 are fastened to each other by a reamer bolt 80. The reamer bolt 80 has a pin portion 80a, a male thread portion 80b integrally molded coaxially with one axial end of the pin portion 80a, and a head portion 80c integrally molded coaxially with the pin portion 80a at the other axial end of the pin portion 80a.

[0042] A plurality of (for example, six in the first embodiment) receiving recesses 81 for receiving reamer bolts 80 are formed at equal intervals in the circumferential direction near the outer periphery on the end face 32a of the base plate portion 32 opposite the end plate portion 30. The receiving recesses 81 have a fitting recess 81a formed on the end face 32a of the base plate portion 32 and a female thread portion 81b for a reamer bolt formed on the bottom of the fitting recess 81a. The male thread portion 80b side of the pin portion 80a of the reamer bolt 80 is fitted into the fitting recess 81a. The male thread portion 80b of the reamer bolt 80 is fastened to the reamer bolt female thread portion 81b.

[0043] Furthermore, a plurality of (for example, four in the first embodiment) mounting bolt female thread portions 85 are formed at equal intervals in the circumferential direction on the end face 32a of the base plate portion 32 radially inward from the receiving recess 81. A pressing plate mounting bolt 91 is fastened to each mounting bolt female thread portion 85.

[0044] The bucket 110 has a block-shaped mounting bracket 113 that is overlaid on the end surface 32a of the base plate portion 32. The mounting bracket 113 is fastened and fixed to the base plate portion 32 of the carrier 14 by a pressure plate 90, a pressure plate mounting bolt 91, and a reamer bolt 80. One side surface 113a of the mounting bracket 113 is overlapped with the end surface 32a of the base plate portion 32. A recess 114 is formed in most of the radial center of the other side surface 113b of the mounting bracket 113. The recess 114 is formed in a circular shape centered on the second rotation axis C2 when viewed from the axial direction. A diameter D1 of the recess 114 is larger than a diameter D2 of a circle centered on the second rotation axis C2 and tangent to the radial outside of the receiving recess 81.

[0045] A fitting hole 116 penetrating in the direction of the second axis of rotation C2 is formed in the radial center of the bottom 114a of the recess 114. The fitting hole 116 is formed in a circular shape centered on the second axis of rotation C2 when viewed from the axial direction. The fitting hole 116 is larger than a diameter D3 of a circle centered on the second axis of rotation C2 and tangent to the radial outside of the mounting bolt female thread portion 85, and smaller than a diameter D4 of a circle tangent to the radial inside of the receiving recess 81. Further, bracket through holes (an example of the through holes in the claims) 115 penetrating in the axial direction are formed in the bottom 114a of the recess 114 at positions radially outward of the fitting holes 116 and corresponding to each receiving recess 81. The bracket through holes 115 communicate with the receiving recess 81. The diameter of the bracket through holes 115 is larger than the diameter of the fitting recess 81a of the receiving recess 81.

[0046] The pressing plate 90 has a plate body 92 that is housed in a recess 114 of the mounting bracket 113, and a fitting portion 93 that protrudes from most of the radial center of the plate body 92 toward the speed reducer unit 3 and fits into a fitting hole 116. The plate body 92 is formed in a disk shape to correspond to the shape of the recess 114. The outer diameter of the plate body 92 is slightly smaller than the inner diameter of the recess 114. Plate through holes 90a penetrating in the axial direction are formed in the plate body 92 at positions corresponding to each bracket through hole 115 of the recess 114. The plate through holes 90a communicate with the bracket through holes 115. The diameter of the plate through holes 90a is slightly larger than the outer diameter of the pin portion 80a of the reamer bolt 80.

[0047] With this configuration, the reamer bolt 80 is inserted into the plate through-hole 90a and the bracket through-hole 115 in this order from the side of the plate body 92 opposite the speed reducer section 3. Then, the male thread portion 80b of the reamer bolt 80 is fastened to the female thread portion 81b for reamer bolt formed in the base plate portion 32 of the carrier 14. As a result, the mounting bracket 113 of the bucket 110 and the pressing plate 90 are fastened and fixed to the base plate portion 32 of the carrier 14 by the reamer bolt 80.

[0048] A cylindrical resin bushing (an example of an interference member in the claims) 82 is fitted onto the outer surface of the pin portion 80a of the reamer bolt 80 at a location corresponding to the bracket through-hole 115. The resin bushing 82 is also fitted onto the inner surface of the bracket through-hole 115. In other words, with the reamer bolt 80 fastened to the base plate portion 32 of the carrier 14, the resin bushing 82 is provided between the outer surface of the reamer bolt 80 and the inner surface of the bracket through-hole 115. In addition, the side of the resin bushing 82 facing the recess 114 of the mounting bracket 113 is covered by the plate body 92 of the pressing plate 90 and is not exposed to the outside.

[0049] The outer surface of the resin bushing 82 is curved like a drum. That is, the diameter of the outer surface of the resin bushing 82 gradually increases from both axial ends toward the axial center. The maximum outer diameter of the resin bushing 82 is the same as or slightly smaller than the diameter of the bracket through-hole 115. The inner diameter of the resin bushing 82 is the same as or slightly larger than the outer diameter of the reamer bolt 80.

[0050] The mechanical strength of the resin bushing 82 is lower than that of the mounting bracket 113 and the reamer bolt 80. The mechanical strength can be expressed, for example, by Young's modulus. If the Young's modulus is low, the mechanical strength is also low. In other words, the Young's modulus of the resin bushing 82 is lower than that of the mounting bracket 113 and the reamer bolt 80. Between the resin bushing 82 and the plate body 92, and between the resin bushing 82 and the base plate portion 32 of the carrier 14, annular spacers 94 are disposed surrounding the reamer bolt 80. The spacers 94 reduce wear on both axial ends of the resin bushing 82.

[0051] The fitting portion 93 of the pressing plate 90 is formed in a cylindrical shape to correspond to the shape of the fitting hole 116 of the mounting bracket 113. The outer diameter of the fitting portion 93 is slightly smaller than the inner diameter of the fitting hole 116. This allows the fitting portion 93 to be fitted into the fitting hole 116 with almost no rattling. The fitting portion 93 has a fitting portion through hole 93a formed therein, which penetrates in the axial direction, at a position corresponding to the female screw portion 85 of the base plate portion 32 for a mounting bolt.

[0052] With this configuration, the presser plate mounting bolt 91 is inserted into the fitting portion through hole 93a from the side of the presser plate 90 opposite the speed reducing portion 3. Then, the presser plate mounting bolt 91 is fastened to the mounting bolt female thread portion 85 of the base plate portion 32. As a result, the presser plate 90 is fastened and fixed to the base plate portion 32 of the carrier 14 by the presser plate mounting bolt 91. In this way, the pressure plate mounting bolt 91 has the role of reliably fixing the mounting bracket 113 of the bucket 110 to the carrier 14 via the pressure plate 90. On the other hand, the reamer bolt 80 has the role of fixing the mounting bracket 113 of the bucket 110 to the carrier 14, while also transmitting the rotation of the carrier 14 to the mounting bracket 113. The transmission function of the reamer bolt 80 will be described in detail below together with the operation of the drive transmission device 1.

[0053] <Operation of the drive transmission device> When the motor 120 provided on the arm 109 is driven, the rotation of the motor shaft 120a is transmitted to the transmission gear 44, which rotates. As a result, the crankshaft 46 and the transmission gear 44 rotate integrally around the crank rotation axis C4. When the crankshaft 46 rotates, the first external gear 48a rotates in mesh with the internal teeth 24 in accordance with the oscillation of the first eccentric portion 46a. Also, the second external gear 48b rotates in mesh with the internal teeth 24 in accordance with the oscillation of the second eccentric portion 46b. In other words, the crankshaft 46 rotates about the crank rotation axis C4 and revolves around the second rotation axis C2.

[0054] In this embodiment, the column portion 33 penetrating the first through holes 48c of both the external gears 48a, 48b is fixed in a fixed position together with the base plate portion 32. This causes the carrier 14 to rotate around the second rotation axis C2 at a reduced speed relative to the rotation of the crankshaft 46. In other words, the carrier 14 rotates around the second rotation axis C2 at a reduced speed relative to the case 11. The case 11 is fixed to an arm 109. Also, a mounting bracket 113 for a bucket 110 is fixed to the carrier 14. Therefore, by driving a motor 120 provided on the arm 109, the bucket 110 is rotated relative to the arm 109 about the second rotation axis C2.

[0055] The power transmission from the carrier 14 to the mounting bracket 113 will now be described in detail. The bucket 110 is fixed to the carrier 14 by the reamer bolt 80, so that when the carrier 14 is rotated, the force of this rotation is transmitted to the mounting bracket 113 of the bucket 110 via the reamer bolt 80 and the resin bushing 82. At this time, the male thread portion 80b of the reamer bolt 80 is fastened to the female thread portion 81b for reamer bolt formed on the base plate portion 32 of the carrier 14, and a part of the pin portion 80a is fitted into the fitting recess 81a of the base plate portion 32. Therefore, although the reamer bolt 80 is cantilevered on the base plate portion 32, it is firmly fixed to the base plate portion 32. Therefore, the rotation of the carrier 14 is reliably transmitted via the reamer bolt 80 and the resin bushing 82.

[0056] Furthermore, the mechanical strength of resin bushing 82 is lower than the mechanical strength of mounting bracket 113 and reamer bolt 80. Therefore, for example, an external impact load applied to bucket 110 is absorbed by resin bushing 82, and the impact load is prevented from being transmitted to carrier 14 via reamer bolt 80. Furthermore, for example, when an external impact load is applied to arm 109, the impact load is prevented from being transmitted to bucket 110 via speed reducer unit 3 and reamer bolt 80.

[0057] In this manner, in the first embodiment described above, the bracket through hole 115 into which the reamer bolt 80 is inserted is formed in the mounting bracket 113 of the bucket 110. The rotation of the carrier 14 is transmitted to the mounting bracket 113 via the reamer bolt 80. Furthermore, a resin bush 82 is provided between the outer surface of the reamer bolt 80 and the inner surface of the bracket through hole 115, which is located midway along the transmission path from the reamer bolt 80 to the mounting bracket 113. That is, the resin bush 82 that absorbs the impact load from the outside is incorporated in the bracket through hole 115. In this manner, no space is required to assemble a device or the like for mitigating the impact load from the outside at a location separated from the reduction gear unit 3. The resin bush 82 for mitigating the impact load from the outside can be incorporated almost as a part of the reduction gear unit 3. Therefore, the drive transmission device 1 can be made smaller while mitigating the impact load from the outside.

[0058] In addition, the resin bushing 82 is used as an interference member that absorbs external impact loads. Therefore, an interference member having a lower mechanical strength than the mounting bracket 113 and the reamer bolt 80 can be easily formed. Furthermore, the resin bushing 82 is formed in a drum shape. Therefore, even if the mounting bracket 113 is slightly tilted relative to the carrier 14 due to a backlash between the carrier 14 and the mounting bracket 113, it is possible to prevent the contact of the mounting bracket 113 with the resin bushing 82 from becoming unbalanced. Therefore, it is possible to prevent the application of an unnecessary load to the reamer bolt 80.

[0059] The receiving recess 81 formed in the base plate portion 32 of the carrier 14 for receiving the reamer bolt 80 has a fitting recess 81a formed in the end face 32a of the base plate portion 32 and a female thread portion 81b for the reamer bolt formed in the bottom of the fitting recess 81a. Therefore, the male thread portion 80b of the reamer bolt 80 is fastened to the female thread portion 81b for the reamer bolt formed in the base plate portion 32 of the carrier 14, and a part of the pin portion 80a is fitted in the fitting recess 81a of the base plate portion 32. As a result, although the reamer bolt 80 is cantilevered by the base plate portion 32, the reamer bolt 80 can be firmly fixed to the base plate portion 32. Therefore, the rotation of the carrier 14 can be reliably transmitted to the mounting bracket 113 via the reamer bolt 80 and the resin bush 82.

[0060] A pressing plate 90 is provided on the bottom 114a of the recess 114 of the mounting bracket 113. A plate through hole 90a is formed in the pressing plate 90, and the reamer bolt 80 is inserted from the side of the pressing plate 90 opposite the speed reducer section 3. The pressing plate 90 presses the resin bush 6 from the side opposite the speed reducer section 3. The pressing plate 90 also covers the side of the resin bush 82 facing the recess 114 of the mounting bracket 113. This prevents the resin bush 82, which has a weak mechanical strength, from being exposed to the outside. This prevents the resin bush 82 from coming into contact with foreign matter such as soil and sand. This extends the product life of the resin bush 82.

[0061] The reduction unit 3 includes a cylindrical case 11, a carrier 14 disposed radially inside the case 11, and a reduction output unit 18 that rotates the carrier 14 at a rotation speed reduced by a fixed ratio to the rotation speed of the motor shaft 120a. The reduction output unit 18 includes a plurality of crankshafts 46, and a first external gear 48a and a second external gear 48b that oscillate and rotate with the rotation of the crankshafts 46. Therefore, the two reduction units 3 can provide high output at a high reduction ratio, so that the boom 108, the arm 109, and the bucket 110 can be operated smoothly while the drive transmission device 1 is made compact. In addition, the reduction unit 3 has a high simultaneous meshing rate between the internal teeth 24 and the external gears 48a, 48b, etc., so that the drive transmission device 1 can be improved in resistance to overload and impact load.

[0062] [Second embodiment] <Drive transmission device> Next, a second embodiment will be described with reference to Fig. 6. Note that the same features as those in the first embodiment are given the same reference numerals and the description thereof will be omitted. 6 is a diagram showing a fixing structure between the speed reducer 203 and the mounting bracket 113 of the bucket 110 in the drive transmission device 201 of the second embodiment. FIG. 6 corresponds to the above-mentioned FIG. As shown in FIG. 6, the difference between the first embodiment described above and this second embodiment is that the fixing structure between the speed reducer section 3 and the bucket 110 in the first embodiment described above is different from the fixing structure between the speed reducer section 203 and the bucket 110 in the second embodiment.

[0063] More specifically, instead of the reamer bolt 80 of the first embodiment, the mounting bracket 110a is fastened to the base portion 232 of the carrier 214 by a bolt (an example of a fixing member in the claims) 83 and a hollow pin (an example of a fixing member in the claims) 84 that fits into the bolt 83. The bolt 83 has a threaded portion 83a and a head portion 83b which is integrally formed coaxially with the threaded portion 83a at one axial end of the threaded portion 83a. The hollow pin 84 is formed in a pipe shape. The inner diameter of the hollow pin 84 is the same as or slightly larger than the outer diameter of the threaded portion 83a of the bolt 83.

[0064] A plurality of (for example, six in the second embodiment) receiving recesses 281 for receiving the screw portion 83a and the hollow pin 84 are formed at equal intervals in the circumferential direction near the outer periphery on the end face 232a of the base plate portion 232 opposite the end plate portion 30. The receiving recesses 281 have a fitting recess 281a formed on the end face 232a of the base plate portion 232 and a female screw portion 281b formed on the bottom of the fitting recess 281a. One end 84a of a hollow pin 84 is fitted into the fitting recess 281a. A threaded portion 83a of a bolt 83 is fastened into the female threaded portion 281b.

[0065] A cylindrical resin bushing (an example of an interference member in the claims) 282 is fitted onto the outer surface of the hollow pin 84 at a location corresponding to the bracket through-hole 115 of the mounting bracket 113. In other words, the hollow pin 84 is fitted between the bolt 83 and the resin bushing 282. The mechanical strength of the resin bushing 282 is lower than the mechanical strength of the mounting bracket 113, the bolt 83, and the hollow pin 84. The outer surface of the resin bushing 282 is curved into a drum shape. The inner diameter of the resin bushing 282 is the same as or slightly larger than the outer diameter of the hollow pin 84.

[0066] Therefore, according to the second embodiment described above, the same effects as those of the first embodiment described above are achieved. In addition, even if the bolt 83 is used instead of the reamer bolt 80 as a fixing member between the speed reducer section 3 and the bucket 110, the amount of tightening of the bolt 83 can be regulated by the hollow pin 84. This makes it possible to maintain the distance between the end face 232a of the base plate section 232 and the pressing plate 90 at an appropriate dimension. This makes it possible to prevent the application of an excessive load to the speed reducer section 3 due to overtightening of the bolt 83.

[0067] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. For example, in the above embodiment, the drive transmission device 1,201 that drives the bucket 110 relative to the arm 109 has been described as being provided with the motor 120 on the arm 109. On the other hand, when driving the boom 108 relative to the revolving body 103, the motor 120 may be provided on either the revolving body 103 or the boom 108. Also, when driving the arm 109 relative to the boom 108, the motor 120 may be provided on either the boom 108 or the arm 109.

[0068] In the above embodiment, the drive transmission device 1, 201 is provided in the shovel 100, which is a construction machine, for driving the boom 108, arm 109, and bucket 110 of the shovel 100. However, the present invention is not limited to this, and the drive transmission device 1, 201 can be used in various devices. For example, when the drive transmission device 1, 201 is provided in a machine other than a construction machine, various drive sources can be used instead of a motor. For example, an engine or the like can be used instead of a motor.

[0069] In the above embodiment, the drive transmission device 1, 201 is described as having two speed reducing units 3 that reduce the speed of rotation of the crankshaft 46 (motor shaft 120a) and output the reduced speed. However, this is not limited to this, and instead of the speed reducing units 3, a speed increasing unit that increases the speed of rotation of the crankshaft 46 (motor shaft 120a) may be provided. Anything that can change the speed of rotation of the crankshaft 46 (motor shaft 120a) may be used.

[0070] In the above-described embodiment, a case has been described in which the resin bushings 82, 282 are used as interference members having a mechanical strength lower than that of the mounting bracket 113, the reamer bolt 80, the bolt 83, and the hollow pin 84. However, this is not limited to this, and various interference members can be used instead of the resin bushings 82, 282. It is sufficient that the mechanical strength of the interference member is lower than that of the mounting bracket 113, the reamer bolt 80, the bolt 83, and the hollow pin 84.

[0071] In the above embodiment, the reduction unit 3 includes the cylindrical case 11, the carrier 14 disposed radially inside the case 11, and the reduction output unit 18 that rotates the carrier 14 at a rotation speed reduced by a fixed ratio to the rotation speed of the motor shaft 120a. The reduction output unit 18 is a so-called eccentric oscillating type reduction unit that includes a plurality of crankshafts 46 and a first external gear 48a and a second external gear 48b that oscillate and rotate with the rotation of the crankshafts 46. However, the reduction unit 3 is not limited to this, and may include a first member (e.g., the case 11) and a second member (e.g., the carrier 14) that rotate relatively around the same second rotation axis C2, and at least one crankshaft (e.g., the crankshaft 46) that is disposed between the first member and the second member and rotates around a rotation axis along the second rotation axis C2 by receiving the rotation of the drive source (e.g., the motor 120). The reduced speed output section 18 may be an eccentric oscillation type reduction section that reduces the rotation of the crankshaft and transmits it to the second member, thereby rotating the second member at a reduced speed relative to the first member.

[0072] For example, an eccentric oscillating type reduction gear unit having one crankshaft will be described in more detail. In this case, the reduction gear unit has a so-called center crankshaft that is coaxial with the second rotation axis C2 as the crankshaft. As the center crankshaft rotates, the first external gear 48a and the second external gear 48b are oscillated and rotated.

[0073] In the above embodiment, a description has been given of a case in which the mounting bracket 113 (bucket 110, second member) is used as a fixing member for the carrier 14, and the reamer bolt 80, the bolt 83, and the hollow pin 84 are used. However, the present invention is not limited to this, and any member capable of fixing the second member to the carrier 14 may be used. In the above embodiment, the boom 108, the arm 109, and the bucket 110 are rotatably connected to each other via the drive transmission device 1. However, this is not limited to this, and it is sufficient that at least one of the rotating body 103 and the boom 108, the boom 108 and the arm 109, and the arm 109 and the bucket 110 is configured to be connected to each other via the drive transmission device 1.

[0074] In the above embodiment, six reamer bolts 80 or bolts 83 (hollow pins 84) are provided and arranged at equal intervals in the circumferential direction to fix the mounting bracket 113 to the carrier 14. Also, four presser plate mounting bolts 91 are provided radially inside the reamer bolts 80 or bolts 83 (hollow pins 84) and arranged at equal intervals in the circumferential direction. However, this is not limited to this, and the number and positions of the reamer bolts 80, bolts 83 (hollow pins 84), and presser plate mounting bolts 91 can be determined arbitrarily. For example, the reamer bolts 80 or bolts 83 (hollow pins 84) and the presser plate mounting bolts 91 may be arranged alternately in the circumferential direction on the same pitch circle.

[0075] The shape of the pressing plate 90 is not limited to that in the above embodiment, and may be configured to press the resin bushings 82, 282 from the side opposite to the speed reducer portion 3. For example, the pressing plate 90 may be formed in a simple plate shape.

[0076] Among the embodiments disclosed in this specification, those that are composed of multiple objects may be integrated, and conversely, those that are composed of one object may be divided into multiple objects. Regardless of whether they are integrated or not, it is sufficient that they are configured to achieve the object of the invention. [Explanation of symbols]

[0077] 1,201…Drive transmission device 3...Reduction section 11. Case 14,214…Carrier (output section) 24…Inner teeth 26...Main bearing (bearing) 46…Crankshaft 48a...First external gear (external tooth member) 48b...Second external gear (external tooth member) 80...Reamer bolt (fixing part) 80a…Pin part 80b…Male thread 81,281…Receiving recess 81a, 281a...Mating recess 81b, 281b…Female thread 82,282...Resin bush (interference part) 83...Bolt (fixing member) 84…Hollow pin 90…Press plate 90a...Through hole 100…Shovel (construction machinery) 103...Rotating body (car body) 109...Arm (first member) 110...Bucket (second member) 113…Mounting bracket 115...Bracket through hole (through hole) 120...Motor (drive source) 120a...Motor shaft (drive source) C2: Second rotation axis (first rotation axis) C4…Crank rotation axis (second rotation axis)

Claims

1. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member provided between an inner surface of the through hole and an outer surface of the fixing member, a mechanical strength of the interference member is lower than a mechanical strength of the second member and a mechanical strength of the fixing member; The fixing member is A pin portion to be inserted into the through hole; a male screw portion integrally formed coaxially with the pin portion at one axial end of the pin portion; having The output unit is A female screw portion into which the male screw portion is fastened; a fitting portion into which the one axial end portion of the pin portion is fitted; have Drive transmission device.

2. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member provided between an inner surface of the through hole and an outer surface of the fixing member, a mechanical strength of the interference member is lower than a mechanical strength of the second member and a mechanical strength of the fixing member; The fixing member is A bolt to be inserted into the through hole; a hollow pin fitted between the bolt and the interference member; having The output unit is A female thread portion into which the bolt is fastened; a fitting portion into which one axial end portion of the hollow pin is fitted; have Drive transmission device.

3. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member provided between an inner surface of the through hole and an outer surface of the fixing member, a mechanical strength of the interference member is lower than a mechanical strength of the second member and a mechanical strength of the fixing member; a pressing plate provided on the opposite side of the output portion across the second member and covering the interference member; The pressing plate has a plate through hole into which the fixing member is inserted. Drive transmission device.

4. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member provided between an inner surface of the through hole and an outer surface of the fixing member, a mechanical strength of the interference member is lower than a mechanical strength of the second member and a mechanical strength of the fixing member; The transmission unit includes: A case and the output portion which rotate relatively about a same first rotation axis; at least one crankshaft that is disposed between the case and the output portion and that receives rotation from the driving source and rotates about a second rotation axis that is aligned with the first rotation axis; an external teeth member having external teeth that is oscillated and rotated about the first rotation axis by the crankshaft; Equipped with the case has internal teeth that mesh with the external teeth and is fixed to the first member; The output portion rotatably supports the crankshaft and is rotatably supported by the case via a bearing, and rotates at a reduced speed relative to the rotation of the crankshaft. Drive transmission device.

5. The interference member is made of resin. The drive transmission device according to any one of claims 1 to 4.

6. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member formed of a resin having a mechanical strength lower than that of the second member and that of the fixing member, the interference member being provided between an inner surface of the through hole and an outer surface of the fixing member; a pressing plate that is provided on the opposite side of the output portion across the second member, has a plate through hole into which the fixing member is inserted, and covers the interference member, The fixing member is A pin portion to be inserted into the through hole; a male screw portion integrally formed coaxially with the pin portion at one axial end of the pin portion; having The output unit is A female screw portion into which the male screw portion is fastened; a fitting portion into which the one axial end portion of the pin portion is fitted; having The transmission unit includes: A case and the output portion which rotate relatively about a same first rotation axis; at least one crankshaft that is disposed between the case and the output portion and that receives rotation from the driving source and rotates about a second rotation axis that is aligned with the first rotation axis; an external teeth member having external teeth that is oscillated and rotated about the first rotation axis by the crankshaft; Equipped with the case has internal teeth that mesh with the external teeth and is fixed to the first member; The output portion is a drive transmission device that rotatably supports the crankshaft and is rotatably supported by the case via a bearing, and rotates at a reduced speed relative to the rotation of the crankshaft.

7. A first member having a drive source that generates a rotational force; a speed change unit provided on the first member and having an output unit that changes the speed of rotation of the drive source and outputs the rotation; a second member having a through hole into which a fixing member is inserted, the second member being fixed to the output portion by the fixing member inserted into the through hole; an interference member formed of a resin having a mechanical strength lower than that of the second member and that of the fixing member, the interference member being provided between an inner surface of the through hole and an outer surface of the fixing member; a pressing plate that is provided on the opposite side of the output portion across the second member, has a plate through hole into which the fixing member is inserted, and covers the interference member, The fixing member is A bolt to be inserted into the through hole; a hollow pin fitted between the bolt and the interference member; having The output unit is A female thread portion into which the bolt is fastened; a fitting portion into which one axial end portion of the hollow pin is fitted; having The transmission unit includes: A case and the output portion which rotate relatively about a same first rotation axis; at least one crankshaft that is disposed between the case and the output portion and that receives rotation from the driving source and rotates about a second rotation axis that is aligned with the first rotation axis; an external teeth member having external teeth that is oscillated and rotated about the first rotation axis by the crankshaft; Equipped with the case has internal teeth that mesh with the external teeth and is fixed to the first member; The output portion is a drive transmission device that rotatably supports the crankshaft and is rotatably supported by the case via a bearing, and rotates at a reduced speed relative to the rotation of the crankshaft.

Images