Speed reducer and construction machine

Abstract

[Problem] To mitigate shock transmitted to a speed reducer. [Solution] A speed reducer is provided with: a speed reduction unit for reducing the speed of input rotation; a first member having a housing part for housing the deceleration part and provided with a through hole for fixing the housing part to the attachment member; and a buffer part which has a cylindrical shape, covers the inner wall of the through hole, and has a first portion and a second portion which have different deformability when subjected to a certain stress.

Description

Technical Field

[0001] The present invention relates to a speed reducer and construction machinery. Background Art

[0002] Conventionally, a device that obtains propulsion force by rotation output from an electric motor has been known. For example, Patent Document 1 describes an electric linear actuator for obtaining propulsion force in a construction device such as a power shovel. In particular, Patent Document 1 describes driving a boom, an arm, a bucket, etc. of a power shovel by the electric linear actuator.

[0003] In addition, in a device that obtains propulsion force by rotation output from an electric motor, a technique for alleviating the impact applied to the device has been known. For example, Patent Document 1 describes an impact alleviation device formed of an elastic body such as a spring that alleviates the impact force applied to a piston of an electric linear actuator.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2013 / 114451 Summary of the Invention

[0007] In order to decelerate the rotation of an electric motor, a speed reducer is sometimes assembled in a device that obtains propulsion force by rotation output from the electric motor. In this case, the impact sometimes is transmitted to the speed reducer. In particular, when the device in which the speed reducer is assembled is used for driving a construction device, for example, driving a boom, an arm, a bucket, etc. of a power shovel, a relatively large impact sometimes is transmitted to the speed reducer. It can be conceived that a part of the speed reducer is damaged because a relatively large impact is transmitted to a part such as a part of the speed reducer that has a function of decelerating the input rotation. Therefore, a technique for alleviating the impact transmitted to the speed reducer, particularly a part of the speed reducer, is sought.

[0008] The present invention has been completed in view of such circumstances, and an object thereof is to alleviate the impact transmitted to the speed reducer.

[0009] A first aspect of the present invention is a speed reducer having:

[0010] a speed reduction unit that decelerates the input rotation;

[0011] a first member that has a housing portion for housing the speed reduction unit and is provided with a through hole for fixing the housing portion to a mounting member; and

[0012] a buffer portion that has a cylindrical shape, covers the inner wall of the through hole, and has a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress.

[0013] The second aspect of the present invention is that in the speed reducer of the above first aspect, the speed reducer further has: a bushing, which is disposed inside the buffer portion and has a cylindrical shape.

[0014] The third aspect of the present invention is that in the speed reducer of the above second aspect, the size of the bushing in the axial direction in which the through hole extends is larger than the size of the through hole in the axial direction.

[0015] The fourth aspect of the present invention is that in the speed reducer of the above second aspect or the above third aspect, the first member further has: a flange portion, which protrudes from the accommodating portion in a direction intersecting the axial direction in which the through hole extends and faces the mounting member,

[0016] The through hole is provided in the flange portion,

[0017] The size of the bushing in the axial direction is larger than the size of the flange portion in the axial direction.

[0018] The fifth aspect of the present invention is that in each of the speed reducers from the above second aspect to the above fourth aspect, the speed reducer further has: a bolt, which passes through the bushing and fixes the accommodating portion to the mounting member,

[0019] The size of the bushing in the radial direction perpendicular to the axis of the through hole is larger than or equal to the size of the head of the bolt in the radial direction.

[0020] The sixth aspect of the present invention is that in each of the speed reducers from the above first aspect to the above fifth aspect, the speed reducer further has: a second member, which can rotate relative to the first member,

[0021] The first member has internal teeth,

[0022] The speed reduction portion has:

[0023] a crankshaft, which is supported by the second member so as to be rotatable; and

[0024] an external gear, which is provided with a through hole for the crankshaft to pass through and has external teeth that mesh with the internal teeth of the first member.

[0025] The seventh aspect of the present invention is that in each of the speed reducers from the second aspect to the fifth aspect, the speed reducer further has:

[0026] the mounting member, which is configured to have a gap in the radial direction perpendicular to the axis of the through hole between it and the first member; and

[0027] a bolt, which passes through the bushing and fixes the accommodating portion to the mounting member,

[0028] The width of the radial gap between the first member and the mounting member is greater than the width of the radial gap between the bushing and the bolt.

[0029] The eighth aspect of the present invention has:

[0030] A reduction unit that reduces the input rotation;

[0031] A first member having a receiving portion for receiving the reduction unit;

[0032] A mounting member that is a mounting member capable of fixing the receiving portion, and is provided with a through hole for fixing the receiving portion to the mounting member; and

[0033] A buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress.

[0034] The ninth aspect of the present invention is a construction machine having a speed reducer according to any one of the above first aspect to the above eighth aspect.

[0035] The tenth aspect of the present invention is a construction machine, wherein

[0036] The construction machine has a speed reducer, the mounting member, and a bolt,

[0037] The speed reducer has:

[0038] A reduction unit that reduces the input rotation;

[0039] A first member having a receiving portion for receiving the reduction unit and provided with a through hole for fixing the receiving portion to the mounting member;

[0040] A buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress; and

[0041] A bushing provided inside the buffer portion and having a cylindrical shape,

[0042] The mounting member is configured to leave a gap in the radial direction perpendicular to the axis of the through hole between the mounting member and the first member,

[0043] A bolt that passes through the bushing and fixes the receiving portion to the mounting member,

[0044] The width of the radial gap between the first member and the mounting member is greater than the width of the radial gap between the bushing and the bolt.

[0045] The eleventh aspect of the present invention is a construction machine, which includes:

[0046] A speed reducer having a speed reduction portion for reducing the rotation of the input and a first member that houses the speed reduction portion;

[0047] A mounting member that can fix the housing portion, and is provided with a through hole for fixing the housing portion to the mounting member;

[0048] A buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress;

[0049] A bushing provided inside the buffer portion and having a cylindrical shape; and

[0050] A bolt that passes through the bushing and fixes the housing portion to the mounting member.

[0051] According to the present invention, the required torque transmission can be performed, and the impact transmitted to the speed reducer can be alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a cross-sectional view of a construction machine according to an embodiment.

[0053] Figure 2 is a cross-sectional view of a speed reducer according to an embodiment.

[0054] Figure 3 is an enlarged view showing Figure 1 an enlarged cross-sectional view of the portion surrounded by the dash-dotted line marked with reference numeral III in

[0055] Figure 4 is an enlarged cross-sectional view of a construction machine according to Modification 1.

[0056] Figure 5 is a cross-sectional view of a construction machine according to Modification 2.

[0057] Figure 6 is a cross-sectional view of a construction machine according to Modification 3.

[0058] Figure 7 is a cross-sectional view of a construction machine according to Modification 4.

[0059] Figure 8 is a cross-sectional view of a construction machine according to Modification 5. DETAILED DESCRIPTION OF THE EMBODIMENT

[0060] This embodiment will be described in detail with reference to the accompanying drawings. First, the construction machine 1 assembled with the speed reducer 4 of this embodiment will be described. Figure 1It is a cross-sectional view showing a structural example of the periphery of the speed reducer 4 of the construction machine 1 equipped with the speed reducer 4. In particular, Figure 1 It is a cross-sectional view obtained by cutting the construction machine 1 equipped with the speed reducer 4 along the plane of the rotation axis LA of the rotation output from the speed reducer 4. Figure 2 It is obtained by using Figure 1 Cross-sectional view of the speed reducer 4 cut along the II-II line.

[0061] The direction in which the rotation axis LA of the rotation output from the speed reducer 4 extends is called the rotation axis direction DA. Based on the end plate portion 421 of the following-described second member 42 of the speed reducer 4 in the rotation axis direction DA, the side where the base plate portion 422 of the following-described second member 42 is located is called the first side SA1. In addition, based on the end plate portion 421 of the second member 42 in the rotation axis direction DA, the side opposite to the side where the base plate portion 422 of the second member 42 is located is called the second side SA2. In Figure 1 The mounting member 47 is located on the second side SA2 of the speed reducer 4 in the rotation axis direction DA. In addition, the direction of rotation around the rotation axis LA is called the rotation axis circumferential direction DB, and the direction perpendicular to the rotation axis LA is called the rotation axis radial direction DC. The rotation axis radial direction DC is the direction in which a perpendicular line drawn from the rotation axis LA extends.

[0062] The construction machine 1 has the speed reducer 4 of the present embodiment. In addition, the construction machine 1 also has an electric motor 3. The speed reducer 4 decelerates the rotation input from the electric motor 3.

[0063] In the present embodiment, the electric motor 3 is a general electric motor. The electric motor 3 has a main body portion 32 and a rotation shaft 31 that rotates relative to the main body portion 32. In Figure 1 The main body portion 32 of the electric motor 3 is fixed to the following-described mounting member 47. Although not shown, the electric motor 3 is fixed to the mounting member 47 with bolts, and thus is fixed to the surface on the second side SA2 of the mounting member 47. As Figure 1 shown, a through hole 471 penetrating the mounting member 47 in the rotation axis direction DA is provided in the mounting member 47. The rotation shaft 31 of the electric motor 3 is inserted into the through hole 471. The rotation shaft 31 protrudes toward the first side SA1 and extends in the rotation axis direction DA. In Figure 1 The rotation axis of the rotation of the rotation shaft 31 coincides with the rotation axis LA of the rotation output from the speed reducer 4.

[0064] The speed reducer 4 will be described. The speed reducer 4 is disposed on the first side SA1 in the rotational axis direction DA of the electric motor 3. The speed reducer 4 has a reduction section 45, a first member 41, and a buffer section 5. The reduction section 45 reduces the input rotation. The first member 41 has a receiving section 48 that houses the reduction section 45. Further, a through hole 41b for fixing the receiving section 48 to an installation member 47 described later is provided in the first member 41. The buffer section 5 has a cylindrical shape and covers the inner wall 41c of the through hole 41b. Further, as will be described later, the buffer section 5 has a first portion 51 and a second portion 52 with different degrees of ease of deformation when subjected to a certain stress. In addition, the speed reducer 4 of the present embodiment further has a bushing 6, a bolt 7, a second member 42, and an installation member 47 described later. Further, in Figure 1 the illustration of the shapes of the first portion 51 and the second portion 52 is omitted, and only the outer shape of the buffer section 5 is shown. Further, in Figure 2 the illustration of the buffer section 5, the bushing 6, and the bolt 7 is omitted.

[0065] The speed reducer 4 has a reduction section 45, a first member 41, and a buffer section 5 and has a second member 42 that can rotate relative to the first member 41. The reduction section 45 reduces the input from the electric motor 3 and causes the first member 41 and the second member 42 to rotate relative to each other.

[0066] In the present embodiment, the first member 41 has internal teeth 412. And the reduction section 45 has: a crankshaft 43 that is supported by the second member 42 so as to be rotatable; an external gear 44 that has a through hole 44d through which the crankshaft 43 passes and has external teeth 441a, 442a. In the reduction section 45, the crankshaft 43 to which rotation is input causes the external gear 44 to eccentrically oscillate. The external teeth 441a, 442a of the external gear 44 mesh with the internal teeth 412 of the first member 41. By the external teeth 441a, 442a of the eccentrically oscillating external gear 44 meshing with the internal teeth 412 of the first member 41, the first member 41 and the second member 42 rotate relative to each other.

[0067] In the present embodiment, the through hole 44d through which the crankshaft 43 passes is provided in the external gear 44.

[0068] In the present embodiment, the reduction section 45 includes a plurality of crankshafts 43. The plurality of crankshafts 43 extend through the through holes 44d of the external gear 44. A plurality of through holes 44d are provided in the external gear 44, and each of the plurality of crankshafts 43 extends through one of the plurality of through holes 44d.

[0069] In the present embodiment, the speed reducer 4 has a cylindrical housing 41a as the first member 41. Further, the speed reducer 4 has a bracket 42a disposed inside the radial direction DC of the rotation axis of the housing 41a (on the side closer to the rotation axis LA in the radial direction DC of the rotation axis) as the second member 42. Further, the speed reducer 4 has an input shaft 46 that imparts a driving force for rotating the bracket 42a. Further, a through hole 471 is provided in the mounting member 47 of the speed reducer 4, and the motor 3 is fixed thereto. The mounting member 47 has a cylindrical shape.

[0070] The first member 41 (housing 41a) has a receiving portion 48 that receives a crankshaft 43 and an external gear 44 as the reduction portion 45. In the present embodiment, the receiving portion 48 is a part of the housing 41a having a cylindrical shape. Further, a through hole 41b for fixing the receiving portion 48 to the mounting member 47 is provided in the first member 41 (housing 41a). The through hole 41b extends in the rotation axis direction DA. By passing a bolt 7 described later through the through hole 41b and screwing it into the mounting member 47, the housing 41a is fixed to the mounting member 47, and the receiving portion 48 is fixed to the mounting member 47. By fixing the housing 41a to the mounting member 47 and fixing the motor 3 to the mounting member 47, the motor 3 can be fixed to the housing 41a via the mounting member 47.

[0071] Internal teeth 412 are provided on the inner peripheral surface of the housing 41a. The internal teeth 412 are pin-shaped (cylindrical) teeth provided on the inner peripheral surface of the housing 41a. In particular, the first member 41 has an internal tooth pin 412a that fits into a pin groove 412b as the internal teeth 412. A plurality of internal teeth 412 are arranged at equal intervals in the circumferential direction DB of the rotation axis.

[0072] The bracket 42a is supported by a pair of main bearings 42j spaced apart in the rotation axis direction DA so as to be rotatable relative to the housing 41a. The main bearings 42j are, for example, angular contact ball bearings. The bracket 42a is arranged coaxially with the housing 41a and the rotation axis LA.

[0073] The bracket 42a has: a disk-shaped end plate portion 421 disposed on the second side SA2 in the rotation axis direction DA; a disk-shaped base plate portion 422 disposed on the first side SA1 in the rotation axis direction DA; and three column portions 423 integrally formed with the base plate portion 422 and protruding from the base plate portion 422 toward the end plate portion 421. Figure 2The column portion 423 shown has a columnar shape, and its cross-section perpendicular to the rotation axis direction DA is a substantially triangular shape with rounded corners. The column portions 423 are arranged at equal intervals in the circumferential direction DB of the rotation axis. The column portion 423 and the end plate portion 421 are fixed by being fastened to each other with bolts 42b in a state where the top surface of the column portion 423 coincides with the end plate portion 421. In this state, a space having a specified width in the rotation axis direction DA is formed between the substrate portion 422 and the end plate portion 421.

[0074] The bolt fastening holes 42c of the fastening bolts 42b are formed in the column portion 423. In addition, bolt insertion holes 42d for inserting the bolts 42b are formed in the end plate portion 421. The bolts 42b inserted into the bolt insertion holes 42d from the opposite side of the column portion 423 with the end plate portion 421 interposed therebetween are fastened to the bolt fastening holes 42c of the column portion 423. Inside the rotation axis radial direction DC closer than the bolts 42b, pins 42e for positioning the end plate portion 421 with respect to the substrate portion 422 are provided. The pins 42e are arranged so as to straddle the column portion 423 and the end plate portion 421. In addition, the column portion 423 may not be integrally formed with the substrate portion 422. In this case, the column portion 423 is fastened to the substrate portion 422. In addition, the shape of the cross-section of the column portion 423 perpendicular to the rotation axis direction DA is not limited to a columnar shape that is a substantially triangular shape with rounded corners. As long as a space having a specified width in the rotation axis direction DA can be formed between the substrate portion 422 and the end plate portion 421 using the column portion 423, the column portion 423 may be cylindrical.

[0075] Plural (for example, three in the present embodiment) hole portions 42f, 42g for inserting the crankshaft 43 of the reduction unit 45 are formed in the end plate portion 421 and the substrate portion 422, respectively. The hole portions 42f, 42g are arranged at equal intervals in the circumferential direction DB of the rotation axis. And, through holes 42h, 42i penetrating in the rotation axis direction DA are formed at the center in the radial direction DC of the end plate portion 421 and the substrate portion 422. The input shaft 46 is arranged coaxially with the housing 41a and the rotation axis LA.

[0076] The base end portion of the input shaft 46 on the motor 3 side (the second side SA2 in the rotation axis direction DA) is coupled to the rotation shaft 31 of the motor 3. Thereby, the input shaft 46 rotates integrally with the rotation shaft 31. The tip portion 46a of the input shaft 46 on the side opposite to the motor 3 (the first side SA1 in the rotation axis direction DA) is disposed in the through hole 42i of the substrate portion 422. A drive gear 461 having external teeth is integrally provided at the tip portion 46a of the input shaft 46.

[0077] The speed reduction unit 45 rotates the carriage 42a at a speed that is reduced from the rotational speed of the input shaft 46 at a specified ratio. The speed reduction unit 45 has a plurality of (for example, three in the present embodiment) transmission gears 431 that mesh with the drive gear 461 and a plurality of (for example, three in the present embodiment) crankshafts 43 with one end fixed to the transmission gear 431. The transmission gear 431 is fixed to one end on the first side SA1 in the rotational axis direction DA of the crankshaft 43. Further, in the present embodiment, the speed reduction unit 45 has a first external gear 441 and a second external gear 442 that swing and rotate as the crankshaft 43 rotates as the external gears 44.

[0078] Since the transmission gear 431 is fixed to one end of the crankshaft 43, the rotation of the rotating shaft 31 is transmitted to the crankshaft 43 via the transmission gear 431. The crankshaft 43 is arranged parallel to the input shaft 46. That is, the crankshaft 43 rotates about a rotational axis parallel to the rotational axis LA of the rotation output from the speed reducer 4. The crankshaft 43 is supported by a first crankshaft bearing 43a so as to be rotatable relative to the end plate portion 421. Further, the crankshaft 43 is supported by a second crankshaft bearing 43b so as to be rotatable relative to the substrate portion 422. The first crankshaft bearing 43a and the second crankshaft bearing 43b are, for example, tapered roller bearings.

[0079] A first eccentric portion 43c and a second eccentric portion 43d that are eccentric from the axis of the crankshaft 43 are formed at the center in the rotational axis direction DA of the crankshaft 43. The first eccentric portion 43c and the second eccentric portion 43d are arranged adjacent to each other in the rotational axis direction DA between the first crankshaft bearing 43a and the second crankshaft bearing 43b. The first eccentric portion 43c is adjacent to the first crankshaft bearing 43a. The second eccentric portion 43d is adjacent to the second crankshaft bearing 43b. Further, the phase angles of the first eccentric portion 43c and the second eccentric portion 43d are offset from each other.

[0080] Such a crankshaft 43 is inserted into the respective hole portions 42f, 42g of the end plate portion 421 and the substrate portion 422. That is, the crankshaft 43 is also arranged at equal intervals in the circumferential direction DB of the rotational axis like the respective hole portions 42f, 42g.

[0081] Further, a first roller bearing 43e is mounted on the first eccentric portion 43c of the crankshaft 43. A second roller bearing 43f is mounted on the second eccentric portion 43d. The first roller bearing 43e is, for example, a cylindrical roller bearing. As the crankshaft 43 rotates, the first external gear 441 and the second external gear 442 swing and rotate via the respective roller bearings 43e, 43f.

[0082] The first external gear 441 and the second external gear 442 are arranged in the space between the base plate portion 422 and the end plate portion 421 of the bracket 42a. The first external gear 441 and the second external gear 442 have external teeth 441a, 442a that mesh with the internal teeth 412 of the housing 41a. A first through hole 44a centered on the rotation axis LA, a second through hole 44b into which the column portion 423 is inserted, and a through hole 44d into which the crankshaft 43 is inserted are formed in the first external gear 441 and the second external gear 442. The eccentric portions 43c, 43d of the crankshaft 43 are inserted into the through hole 44d. The input shaft 46 is inserted into the first through hole 44a.

[0083] The first eccentric portion 43c of the crankshaft 43 and the first roller bearing 43e are inserted into the through hole 44d of the first external gear 441. The second eccentric portion 43d of the crankshaft 43 and the second roller bearing 43f are inserted into the through hole 44d of the second external gear 442. Thus, the first eccentric portion 43c and the second eccentric portion 43d swing and rotate with the rotation of the crankshaft 43, and accordingly, the first external gear 441 and the second external gear 442 swing and rotate while meshing with the internal teeth 412 of the housing 41a.

[0084] The operation of the speed reducer 4 will be described. If the drive motor 3 is driven, the input shaft 46 is driven integrally with the rotating shaft 31. Then, by the rotation of the input shaft 46, the transmission gear 431 rotates via the drive gear 461. Thus, the crankshaft 43 rotates integrally with the transmission gear 431.

[0085] If the crankshaft 43 rotates, the first external gear 441 rotates while meshing with the internal teeth 412 as the first eccentric portion 43c swings. In addition, the second external gear 442 rotates while meshing with the internal teeth 412 as the second eccentric portion 43d swings. That is, the crankshaft 43 rotates about a rotation axis parallel to the rotation axis LA of the rotation output from the speed reducer 4 and revolves around the rotation axis LA. In this way, by the rotation of the crankshaft 43, the first external gear 441 and the second external gear 442 can be driven.

[0086] If the first external gear 441 and the second external gear 442 are driven, the second member 42 (bracket 42a) into which the column portion 423 has been inserted into the first external gear 441 and the second external gear 442 is driven by the first external gear 441 and the second external gear 442. Thus, the bracket 42a rotates at a speed lower than that of the input shaft 46 with respect to the housing 41a fixed to the motor 3 by the mounting member 47. Thus, the rotation of the motor 3 can be decelerated by the speed reducer 4.

[0087] In addition, as the speed reducer 4, the speed reducer 4 having the crankshaft 43 and the external gear 44 in particular for the speed reduction part 45 has been described, but the form of the speed reducer 4 is not limited thereto. The speed reduction part 45 of the speed reducer 4 may also have a planetary gear rotatably supported by the second member 42, and the first member 41 and the second member 42 rotate relative to each other by the planetary gear that rotates upon input meshing with the internal teeth 412 of the first member 41. That is, the speed reducer 4 may also be a planetary gear speed reducer.

[0088] The details of the through holes 41b and the buffer part 5 and the bushing 6 will be described. In the present embodiment, a plurality of through holes 41b are provided in the first member 41. Figure 3 is an enlarged cross-sectional view showing an enlarged portion surrounded by the double-dot chain line with the reference numeral III marked in Figure 1 . In Figure 1 , the dotted line with the reference numeral LB marked is an imaginary line indicating the axis LB of the through hole 41b. The axis LB is an imaginary line passing through the centroid of the cross-section of the through hole 41b. For example, in the case where the through hole 41b has a cylindrical shape, the axis LB is a straight line passing through the center of the circle of the cross-section of the through hole 41b. The extending direction of the through hole 41b (the direction in which the axis LB of the through hole 41b extends) is also referred to as the axis direction DD. In the present embodiment, the axis direction DD in which the through hole 41b extends is parallel to the rotation axis direction DA in which the rotation axis LA of the rotation output from the speed reducer 4 extends. In the axis direction DD, with the through hole 41b as a reference, the side where the mounting member 47 is located is referred to as the first side SD1. In addition, in the axis direction DD, with the through hole 41b as a reference, the side opposite to the side where the mounting member 47 is located is referred to as the second side SD2. In addition, the direction around the axis LB of the through hole 41b is referred to as the circumferential direction DE. In addition, the direction perpendicular to the axis LB of the through hole 41b is referred to as the radial direction DF. The radial direction DF is the extending direction of the perpendicular line that can be drawn from the axis LB.

[0089] In the present embodiment, a plurality of through holes 41b are arranged in the circumferential direction DB of the rotation axis around the rotation axis LA. The plurality of through holes 41b surround the accommodation part 48 from the outside in the radial direction DC of the rotation axis perpendicular to the rotation axis LA. The number of the through holes 41b can be appropriately changed according to the magnitude of the torque required to be transmitted when the torque is transmitted from the motor 3 to the speed reducer 4. In this case, the buffer parts 5 described later are respectively provided in the plurality of through holes 41b.

[0090] In the present embodiment, the first member 41 further has a flange portion 49 which protrudes from the accommodating portion 48 in a direction crossing the axial direction DD in which the through hole 41b extends, and faces the mounting member 47. In the present embodiment, the flange portion 49 protrudes from the accommodating portion 48 to the outside in the radial direction DC of the rotation axis. Further, the flange portion 49 extends in the circumferential direction DB of the rotation axis. Thus, the flange portion 49 surrounds the accommodating portion 48 from the outside in the radial direction DC of the rotation axis. And the through hole 41b is provided in the flange portion 49. In the present embodiment, the mounting member 47 has a mounting surface 47a provided with a screw hole 47b. And the flange portion 49 has a surface facing the mounting surface 47a. The surface of the flange portion 49 facing the mounting surface 47a (the surface on the first side SD1 in the axial direction DD) is referred to as the first surface 49a. Further, the surface of the flange portion 49 on the side opposite to the first surface 49a side in the axial direction DD (the surface on the second side SD2 in the axial direction DD) is referred to as the second surface 49b. In the present embodiment, the first surface 49a, the second surface 49b and the mounting surface 47a are surfaces perpendicular to the axial direction DD. And a plurality of through holes 41b are provided so as to open on the first surface 49a and the second surface 49b of the flange portion 49.

[0091] The speed reducer 4 has a buffer portion 5 which has a cylindrical shape and covers the inner wall 41c of the through hole 41b. When the mounting member 47 is subjected to an impact, the buffer portion 5 alleviates the impact transmitted from the mounting member 47 to the first member 41. In the present embodiment, the buffer portion 5 has a substantially cylindrical shape. By having a cylindrical shape, the buffer portion 5 has a buffer portion through hole 5a extending in the axial direction DD. A bolt 7 described later passes through the buffer portion through hole 5a. In the present embodiment, the buffer portion 5 continuously adheres to the inner wall 41c of the through hole 41b in the circumferential direction DE. The buffer portion 5 is fixed to the inner wall 41c of the through hole 41b. The buffer portion 5 is fixed to the inner wall 41c of the through hole 41b, for example, by bonding to the inner wall 41c of the through hole 41b using an adhesive.

[0092] The buffer portion 5 has a first portion 51 and a second portion 52, and the ease of deformation of the first portion 51 and the second portion 52 is different when a certain stress is applied. Both the first portion 51 and the second portion 52 have a cylindrical shape. In the present embodiment, the first portion 51 has a substantially cylindrical shape. The second portion 52 has a cylindrical shape. The second portion 52 is located at a position closer to the inside in the radial direction DF (on the side closer to the axis LB in the radial direction DF) than the first portion 51. The first portion 51 continuously adheres to the inner wall 41c of the through hole 41b in the circumferential direction DE. The second portion 52 continuously adheres to the inner wall 51a of the first portion 51 in the circumferential direction DE. The second portion 52 is fixed to the inner wall 51a of the first portion 51, for example, by bonding to the inner wall 51a of the first portion 51 using an adhesive.

[0093] In the present embodiment, the second part 52 is more likely to deform than the first part 51 when subjected to a certain stress. Here, as an index of the ease of deformation when subjected to a certain stress, for example, the magnitudes of elongation of the first part 51 and the second part 52 when the first part 51 and the second part 52 are subjected to a certain tensile stress can be used. That is, the magnitudes of elongation of the first part 51 and the second part 52 when subjected to a certain tensile stress are measured. If the magnitude of elongation of the second part 52 is larger than that of the first part 51, it is considered that the second part 52 is more likely to deform than the first part 51 when subjected to a certain stress. The magnitudes of elongation of the first part 51 and the second part 52 when subjected to a certain tensile stress can be compared, for example, by the following method. According to JIS K6251:2017, test pieces having the same shape are made for the first part 51 and the second part 52, and a tensile testing machine is prepared. Then, using this tensile testing machine, the test pieces are stretched in such a way as to apply a certain tensile stress to the test pieces. Then, the magnitude of elongation of the test pieces when the test pieces are stretched is measured. Then, the magnitudes of elongation of the measured test pieces are compared between the first part 51 and the second part 52.

[0094] In addition, as an index of the ease of deformation when subjected to a certain stress, the magnitudes of shrinkage of the first part 51 and the second part 52 when the first part 51 and the second part 52 are subjected to a certain compressive stress can also be used. That is, the magnitudes of shrinkage of the first part 51 and the second part 52 when subjected to a certain compressive stress are measured. If the magnitude of shrinkage of the second part 52 is larger than that of the first part 51, it is considered that the second part 52 is more likely to deform than the first part 51 when subjected to a certain stress. The magnitudes of shrinkage of the first part 51 and the second part 52 when subjected to a certain compressive stress can be compared, for example, by the following method. According to JIS K6254:2016, test pieces having the same shape are made for the first part 51 and the second part 52, and a compression testing machine is prepared. Then, using this compression testing machine, the test pieces are stretched in such a way as to apply a certain compressive stress to the test pieces. Then, the magnitude of shrinkage of the test pieces when the test pieces are stretched is measured. Then, the magnitudes of shrinkage of the measured test pieces are compared between the first part 51 and the second part 52.

[0095] In the present embodiment, the buffer portion 5 has a first flange portion 53 that overlaps with the first surface 49a of the flange portion 49 and a second flange portion 54 that overlaps with the second surface 49b of the flange portion 49. The buffer portion 5 has a cylindrical buffer portion main body portion 55, the first flange portion 53, and the second flange portion 54. The first flange portion 53 is connected to the end portion on the first side SD1 in the axial direction DD of the buffer portion main body portion 55. The second flange portion 54 is connected to the end portion on the second side SD2 in the axial direction DD of the buffer portion main body portion 55. The first flange portion 53 and the second flange portion 54 respectively protrude outward in the radial direction DF from the buffer portion main body portion 55. The first flange portion 53 contacts the first surface 49a of the flange portion 49. The second flange portion 54 contacts the second surface 49b of the flange portion 49.

[0096] In the present embodiment, the first portion 51, which is located on the outer side in the radial direction DF (on the side away from the axis LB in the radial direction DF) relative to the second portion 52 and is more difficult to deform than the second portion 52 when subjected to a certain stress, forms the first flange portion 53 and the second flange portion 54.

[0097] In the present embodiment, when subjected to a certain stress, the first portion 51 and the second portion 52 are more easily deformed than the mounting member 47, the first member 41, the bolt 7, and a bushing 6 described later. The ease of deformation of the first portion 51 and the second portion 52 when subjected to a certain stress can be ensured either by selecting the materials of the first portion 51 and the second portion 52 or by increasing the proportion of voids contained in the first portion 51 and the second portion 52. The materials of the first portion 51 and the second portion 52 are not particularly limited as long as they can mitigate the impact transmitted from the mounting member 47 to the first member 41. The materials of the first portion 51 and the second portion 52 can be either resin or metal. For example, the materials of the first portion 51 and the second portion 52 are rubber.

[0098] The buffer portion 5 has the first flange portion 53 and the second flange portion 54, thereby being able to prevent the buffer portion 5 from detaching from the through hole 41b.

[0099] The speed reducer 4 further includes a bushing 6 having a cylindrical shape disposed inside the buffer portion 5. In the present embodiment, the bushing 6 has a cylindrical shape. Since the bushing 6 has a cylindrical shape, it has a bushing through-hole 6a extending in the axial direction DD. A bolt 7 described later passes through the bushing through-hole 6a. In the present embodiment, the bushing 6 is continuously in close contact with the inner wall 5b of the buffer portion through-hole 5a in the circumferential direction DE. The bushing 6 is fixed to the inner wall 5b of the buffer portion through-hole 5a. For example, the bushing 6 is fixed to the inner wall 5b of the buffer portion through-hole 5a by bonding with an adhesive. The end portion on the first side SD1 in the axial direction DD of the bushing 6 is referred to as the first end portion 6b. In addition, the end portion on the second side SD2 in the axial direction DD of the bushing 6 is referred to as the second end portion 6c.

[0100] As the material of the bushing 6, a material that can be fixed to the mounting member 47 using the bolt 7 is selected. In the present embodiment, the material of the bushing 6 is metal. As an example, the material of the bushing 6 is iron.

[0101] In the present embodiment, the dimension w1 of the bushing 6 in the axial direction DD in which the through-hole 41b extends is larger than the dimension w2 of the through-hole 41b in the axial direction DD. Thereby, the bushing 6 can be configured to protrude from the through-hole 41b on both sides of the through-hole 41b.

[0102] In addition, in the present embodiment, the dimension w1 of the bushing 6 in the axial direction DD is larger than the dimension w3 of the flange portion 49 in the axial direction DD. Thereby, the first end portion 6b of the bushing 6 can be disposed at a position closer to the first side SD1 in the axial direction DD than the first surface 49a of the flange portion 49, and the second end portion 6c of the bushing 6 can be disposed at a position closer to the second side SD2 in the axial direction DD than the second surface 49b of the flange portion 49.

[0103] In addition, in the present embodiment, the speed reducer 4 further has a bolt 7 that passes through the bushing 6 to fix the accommodating portion 48 to the mounting member 47. In the present embodiment, the bolt 7 has a shaft portion 7a provided with an external thread 7b and a head 7c provided at one end of the shaft portion 7a. The size w4 of the bushing through-hole 6a on the radial direction DF perpendicular to the axis LB of the through-hole 41b is greater than or equal to the size w5 of the shaft portion 7a on the radial direction DF. In addition, the size w4 of the bushing through-hole 6a on the radial direction DF is smaller than the size w6 of the head 7c on the radial direction DF. Therefore, by passing the shaft portion 7a through the bushing through-hole 6a and thread-connecting the end portion on the side opposite to the side where the head 7c is provided on the shaft portion 7a to the screw hole 47b of the mounting member 47, the bushing 6 can be clamped between the head 7c and the mounting member 47. By clamping the bushing 6 between the head 7c and the mounting member 47, the bushing 6 is fixed to the mounting member 47. In addition, in the present embodiment, the bushing 6 is fixed to the inner wall 5b of the buffer portion through-hole 5a, and the buffer portion 5 is fixed to the inner wall 41c of the through-hole 41b. Therefore, by fixing the bushing 6 to the mounting member 47 using the bolt 7, the first member 41 including the accommodating portion 48 can be fixed to the mounting member 47 via the bushing 6 and the buffer portion 5.

[0104] In addition, the size w7 of the bushing 6 on the radial direction DF perpendicular to the axis LB of the through-hole 41b is greater than or equal to the size w6 of the head 7c of the bolt 7 on the radial direction DF.

[0105] In addition, in the present embodiment, the speed reducer 4 further has a mounting member 47, and the mounting member 47 is configured to leave a gap in the radial direction DF perpendicular to the axis LB of the through-hole 41b between it and the first member 41. That is, in the present embodiment, the mounting member 47 is a part of the speed reducer 4. As described above, the mounting member 47 of the present embodiment is a member that fixes the motor 3.

[0106] In some cases, the first member 41 and the mounting member 47 have opposing surfaces in the radial direction DF. In Figure 3 , the surface 41d of the first member 41 and the surface 47c of the mounting member 47 are opposed in the radial direction DF. Here, in the present embodiment, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is greater than the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF.

[0107] Here, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is the minimum distance between the first member 41 and the mounting member 47 considering the distances between the first member 41 and the mounting member 47 in all directions parallel to the plane perpendicular to the axis LB of the through-hole 41b. In addition, the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF is the width of the gap between the bushing 6 and the bolt 7 in the radial direction DF when the bolt 7 is arranged in the through-hole 41b such that the axis of the bolt 7 coincides with the axis LB of the through-hole 41b.

[0108] As described above, the speed reducer 4 of the present embodiment has: a speed reduction unit 45 that reduces the input rotation; a first member 41 that has a housing portion 48 for housing the speed reduction unit 45 and is provided with a through-hole 41b for fixing the housing portion 48 to the mounting member 47; and a buffer portion 5 that has a cylindrical shape, covers the inner wall 41c of the through-hole 41b, and has a first portion 51 and a second portion 52 with different degrees of ease of deformation when subjected to a certain stress. The number of the through-holes 41b is set to be able to transmit the torque of the magnitude required to be transmitted when transmitting the torque from the motor 3 to the speed reducer 4, and the buffer portions 5 are respectively provided in each of the plurality of through-holes 41b. With this speed reducer 4, the following effects can be obtained. The mounting member 47 is subjected to an impact. For example, when the speed reducer 4 is assembled to a construction machine 1 such as a power excavator, the impact received by the construction machine 1 from the outside is transmitted to the mounting member 47, and the mounting member 47 is subjected to an impact. At this time, the impact received by the mounting member 47 is also transmitted to the bolt 7 that is threadedly connected to the threaded hole 47b of the mounting member 47 through the through-hole 41b. In this case, the bolt 7 moves in the radial direction DF due to the received impact and transmits the impact to the first member 41. When the speed reducer 4 further has a bushing 6, due to the impact received by the bolt 7, both the bolt 7 and the bushing 6 move in the radial direction DF, and the impact received by the bolt 7 is transmitted to the first member 41 via the bushing 6. Here, the speed reducer 4 of the present embodiment has a buffer portion 5 that has a cylindrical shape and covers the inner wall 41c of the through-hole 41b. The buffer portion 5 is arranged between the bolt 7 and the first member 41 in the radial direction DF. Therefore, when the bolt 7 moves in the radial direction DF and is about to transmit an impact to the first member 41, the impact transmitted from the bolt 7 to the first member 41 can be mitigated by the buffer portion 5. Thus, by the buffer portion 5, the impact transmitted from the bolt 7 via the first member 41 to the speed reduction unit 45 can be mitigated. As described above, the impact transmitted to the speed reducer 4 can be mitigated by the buffer portion 5, and in particular, the impact transmitted to the first member 41 and the speed reduction unit 45, which are parts of the speed reducer 4, can be mitigated.

[0109] In the present embodiment, the buffer portion 5 has a first portion 51 and a second portion 52 that differ in ease of deformation when subjected to a certain stress. In the present embodiment, the second portion 52 is more easily deformed than the first portion 51 when subjected to a certain stress. Both the first portion 51 and the second portion 52 have a cylindrical shape. The buffer portion 5 has the first portion 51 and the second portion 52, thereby achieving the following effects. When the bolt 7 moves in the radial direction DF and is about to transmit an impact to the first member 41, the impact can be effectively mitigated by the second portion 52 that is easily deformed. In addition, since the impact from the bolt 7 is particularly large, the second portion 52 may be deformed to the extent that there is no further room for deformation. In this case, the first portion 51 that is less easily deformed than the second portion 52 can also be used to mitigate the impact.

[0110] In addition, the buffer portion 5 has the first portion 51 and the second portion 52, thereby also achieving the following effects. Compared with the case where the buffer portion 5 is formed only by the second portion 52 that is more easily deformed than the first portion 51, the buffer portion 5 is less likely to be deformed. Thus, when rotation is input to the speed reducer 4, it is possible to suppress the loss of the input rotational force due to the buffer portion 5. In particular, as in the present embodiment, when rotation is input from the motor 3 fixed to the mounting member 47 to the speed reducer 4, it is possible to suppress the loss of the rotational force input from the motor 3 due to the buffer portion 5. In particular, the first portion 51 that is more difficult to deform than the second portion 52 can be set such that it is not easily deformed when a conventional level of force is applied during the input of rotation to the speed reducer 4. In this case, when rotation is input to the speed reducer 4, even if the second portion 52 is deformed, it is possible to suppress the deformation of the first portion 51. When rotation is input to the speed reducer 4, by suppressing the deformation of the first portion 51, it is possible to reduce the amount of rotational force lost due to the buffer portion 5 and appropriately transmit torque from the motor 3 to the speed reducer 4. Thus, it is possible to efficiently input rotation to the speed reducer 4 while providing the buffer portion 5.

[0111] As described above, according to the buffer portion 5 of the present embodiment, the second portion 52 can be set as the portion that undergoes a larger deformation than the first portion 51 and significantly mitigates the impact when the bolt 7 moves in the radial direction DF and is about to transmit an impact to the first member 41. In addition, the first portion 51 can be set as the portion that further mitigates the impact when the impact transmitted from the bolt 7 moving in the radial direction DF to the first member 41 is particularly large and the second portion 52 has been completely deformed. In addition, the first portion 51 can also be set such that it is not easily deformed when a conventional level of force is applied during the input of rotation to the speed reducer 4. Thus, by providing the buffer portion 5 in the speed reducer 4, it is possible to mitigate the impact transmitted from the bolt 7 to the first member 41 in the radial direction DF, improve the efficiency of inputting rotation to the speed reducer 4, and improve the efficiency of the speed reducer 4 in outputting the decelerated rotation.

[0112] In addition, the speed reducer 4 of the present embodiment further includes a bushing 6 disposed inside the buffer portion 5 and having a cylindrical shape. Thus, by fixing the bushing 6 to the buffer portion 5 and fixing the buffer portion 5 to the first member 41, and fixing the bushing 6 to the mounting member 47 with bolts 7, the first member 41 having the receiving portion 48 can be stably fixed to the mounting member 47 via the bushing 6 and the buffer portion 5.

[0113] In addition, in the present embodiment, the dimension w1 of the bushing 6 in the axial direction DD in which the through hole 41b extends is larger than the dimension w2 of the through hole 41b in the axial direction DD. Thus, the bushing 6 can be arranged to protrude from the through hole 41b on both sides of the through hole 41b. In addition, in the present embodiment, the dimension w1 of the bushing 6 in the axial direction DD is larger than the dimension w3 of the flange portion 49 in the axial direction DD. Thus, the first end portion 6b of the bushing 6 can be arranged at a position closer to the first side SD1 in the axial direction DD than the first surface 49a of the flange portion 49, and the second end portion 6c of the bushing 6 can be arranged at a position closer to the second side SD2 in the axial direction DD than the second surface 49b of the flange portion 49.

[0114] By arranging the bushing 6 in this way, the following effects can be obtained. The bushing 6 protrudes from the through hole 41b on the first side SD1 of the through hole 41b, and the first end portion 6b of the bushing 6 is arranged at a position closer to the first side SD1 in the axial direction DD than the first surface 49a of the flange portion 49. Thus, the first end portion 6b of the bushing 6 contacts the mounting surface 47a of the mounting member 47. As a result, the mounting surface 47a of the mounting member 47 is separated from the surface (the first surface 49a of the flange portion 49) of the first member 41 that faces the mounting surface 47a in the axial direction DD. Thus, it is possible to suppress direct contact between the mounting member 47 and the first member 41 in the axial direction DD, and it is possible to suppress direct transmission of impact from the mounting member 47 to the first member 41 in the axial direction DD. In addition, the bushing 6 protrudes from the through hole 41b on the second side SD2 of the through hole 41b, and the second end portion 6c of the bushing 6 is arranged at a position closer to the second side SD2 in the axial direction DD than the second surface 49b of the flange portion 49. Thus, the following effects can be obtained. By sandwiching the bushing 6 between the head 7c of the bolt 7 and the mounting member 47, when the bushing 6 is fixed to the mounting member 47, contact between the head 7c of the bolt 7 and the first member 41 is suppressed. Thus, it is possible to suppress direct transmission of impact from the head 7c of the bolt 7 to the first member 41.

[0115] In addition, the speed reducer 4 of the present embodiment further includes a bolt 7 that passes through the bushing 6 and fixes the accommodating portion 48 to the mounting member 47. The size w7 of the bushing 6 in the radial direction DF perpendicular to the axis LB of the through hole 41b is greater than or equal to the size w6 of the head 7c of the bolt 7 in the radial direction DF. Thus, when the bushing 6 is sandwiched between the head 7c of the bolt 7 and the mounting member 47 and the bushing 6 is fixed to the mounting member 47, contact between the head 7c of the bolt 7 and the first member 41 can be suppressed. Accordingly, transmission of impact from the head 7c of the bolt 7 directly to the first member 41 can be suppressed. In addition, when the bushing 6 is sandwiched between the head 7c of the bolt 7 and the mounting member 47 and the bushing 6 is fixed to the mounting member 47, the area of contact between the head 7c and the bushing 6 can be ensured. Accordingly, the bushing 6 can be stably fixed to the mounting member 47, the efficiency of inputting rotation from the motor 3 fixed to the mounting member 47 to the speed reducer 4 can be increased, and the efficiency of outputting the decelerated rotation by the speed reducer 4 can be increased.

[0116] In addition, the speed reducer 4 of the present embodiment further includes a second member 42 that can rotate relative to the first member 41. The first member 41 has internal teeth 412. The speed reduction portion 45 includes: a crankshaft 43 that is supported by the second member 42 so as to be rotatable; and an external gear 44 that is provided with a through hole 44d through which the crankshaft 43 passes and has external teeth 441a, 442a that mesh with the internal teeth 412 of the first member 41. Even with such a structure, the speed reducer 4 of the present embodiment can stably protect the speed reducer 4 from impact.

[0117] In addition, the speed reducer 4 of the present embodiment further includes: a mounting member 47 that is configured to leave a gap in the radial direction DF perpendicular to the axis LB of the through hole 41b between it and the first member 41; and a bolt 7 that passes through the bushing 6 and fixes the accommodating portion 48 to the mounting member 47. The width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is greater than the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF. Thus, the following effects can be obtained. When the mounting member 47 is impacted and moves in the radial direction DF to transmit the impact to the first member 41, a surface other than the mounting surface 47a of the mounting member 47 may come into direct contact with the surface of the first member 41. For example, in Figure 3In this case, the surface 41d of the first member 41 opposite on the radial DF may also be in direct contact with the surface 47c of the mounting member 47. Here, by making the width w8 greater than the width w9, when the mounting member 47 is impacted and moves along the radial DF, the bolt 7 can be brought into contact with the buffer portion 5 on the radial DF before the surface of the mounting member 47 comes into direct contact with the surface of the first member 41 on the radial DF. Therefore, before the surface of the mounting member 47 comes into direct contact with the surface of the first member 41 on the radial DF, the impact can be mitigated by the buffer portion 5. Thereby, it is possible to suppress the transmission of a strong impact from the mounting member 47 to the first member 41 due to the direct contact of the surface of the mounting member 47 and the surface of the first member 41 on the radial DF.

[0118] The speed reducer 4 of the present embodiment described above can be used in a construction machine 1. In this case, it can be said that the construction machine 1 has the speed reducer 4. The construction machine 1 is, for example, a power excavator. When the construction machine 1 is a power excavator, the speed reducer 4 outputs rotation for driving components such as the boom, arm, and bucket of the power excavator. According to the construction machine 1 having the speed reducer 4 of the present embodiment, the construction machine 1 can be driven by the rotation decelerated by the speed reducer 4, and the impact transmitted to the first member 41 of the speed reducer 4 can be mitigated.

[0119] The present embodiment has been described by way of specific examples, but these specific examples do not limit the present embodiment. The present embodiment described above can be implemented in various other specific examples, and various omissions, substitutions, changes, and additions can be made without departing from its gist.

[0120] Next, an example of a modification will be described with reference to the drawings. In the following description and the drawings used in the following description, for parts that can be configured in the same manner as the above specific examples, the same reference numerals as those used for the corresponding parts in the above specific examples are used, and repeated descriptions are omitted.

[0121] (Modification 1)

[0122] In the above embodiment, the case where the second portion 52 that is more easily deformed than the first portion 51 when a certain stress is applied is located closer to the inner side of the radial DF in the buffer portion 5 has been described. However, the form of the buffer portion 5 is not limited to this. Figure 4 FIG. is an enlarged cross-sectional view showing the vicinity of the buffer portion 5 of the cross-section of the construction machine 1 of Modification 1 in an enlarged manner. In particular, Figure 4 FIG. shows a cross-section of the construction machine 1 obtained by cutting the construction machine 1 with a plane passing through the axis LB of the through-hole 41b.

[0123] In Modification 1, a second part 52 that is more easily deformable than the first part 51 when subjected to a certain stress is located at a position closer to the inner side in the radial direction DF than the first part 51. In this case, by using the buffer part 5 having the first part 51 and the second part 52, the impact transmitted from the bolt 7 to the first member 41 can be mitigated, the efficiency of inputting rotation to the speed reducer 4 can be improved, and the efficiency of outputting the decelerated rotation by the speed reducer 4 can also be improved.

[0124] In addition, in Modification 1, the first part 51 located at a position closer to the inner side in the radial direction DF than the second part 52 forms a first flange part 53 and a second flange part 54. In this case, the buffer part 5 can also be prevented from coming off from the through-hole 41b by the first flange part 53 and the second flange part 54.

[0125] (Modification 2)

[0126] In the above-described embodiment and modification, an example in which the mounting member 47 is regarded as a part of the speed reducer 4 has been described. However, the form of the mounting member 47 is not limited to this. Figure 5 It is a cross-sectional view showing a structural example around the speed reducer 4 of the construction machine 1 in which the speed reducer 4 of Modification 2 is assembled. In particular, Figure 5 It is a cross-sectional view obtained by cutting the construction machine 1 along a plane passing through the rotation axis LA of the rotation output from the speed reducer 4.

[0127] In Modification 2, the mounting member 47 is a member that forms a part of the construction machine 1 and is particularly large compared to the first member 41 and the speed reduction part 45 of the speed reducer 4. As an example, the mounting member 47 of Modification 2 is an object member that is rotationally driven by the rotation output from the speed reduction part 45. As an example, when the construction machine 1 is a hydraulic excavator, the mounting member 47 of Modification 2 is a member that forms the boom, arm, bucket, etc. of the hydraulic excavator. In Modification 2, the electric motor 3 is directly fixed to the mounting member 47.

[0128] In other words, the construction machine 1 of Modification 2 includes a speed reducer 4, a mounting member 47, and a bolt 7. The speed reducer 4 has a reduction section 45 that reduces the input rotation, a first member 41 that has a housing section 48 for housing the reduction section 45 and is provided with a through hole 41b for fixing the housing section 48 to the mounting member 47, a buffer section 5 that has a cylindrical shape, covers the inner wall 41c of the through hole 41b, and has a first section 51 and a second section 52 with different degrees of ease of deformation when subjected to a certain stress, and a bushing 6 that has a cylindrical shape and is provided inside the buffer section 5. The mounting member 47 is configured such that a gap is provided in the radial direction DF perpendicular to the axis LB of the through hole 41b between the mounting member 47 and the first member 41, and the bolt 7 passes through the bushing 6 to fix the housing section 48 to the mounting member 47. Further, in Modification 2, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is greater than the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF.

[0129] Similar to the speed reducer 4 of the above-described embodiment, in the construction machine 1 of Modification 2, since the width w8 is greater than the width w9, when the mounting member 47 is impacted and moves in the radial direction DF, the bolt 7 comes into contact with the buffer section 5 in the radial direction DF before the surfaces of the mounting member 47 and the first member 41 directly contact each other in the radial direction DF.

[0130] (Modification 3)

[0131] In the above-described embodiment and each modification, an example in which the transmission gear 431 is fixed to one end on the first side SA1 in the rotational axis direction DA of the crankshaft 43 has been described. However, the form of the speed reducer 4 is not limited to this. Figure 6 FIG. is a cross-sectional view showing a structural example around the electric motor 3 and the speed reducer 4 of the construction machine 1 equipped with the speed reducer 4 of Modification 3. In particular, Figure 6 FIG. is a cross-sectional view obtained by cutting the construction machine 1 along a plane passing through the rotational axis LA of the rotation output from the speed reducer 4.

[0132] In Modification 3, the transmission gear 431 is fixed to one end on the second side SA2 in the rotational axis direction DA of the crankshaft 43. Further, the transmission gear 431 is arranged on the second side SA2 in the rotational axis direction DA of the first external gear 441 and the second external gear 442. And the drive gear 461 provided at the tip 46a of the input shaft 46 meshes with the transmission gear 431 on the second side SA2 in the rotational axis direction DA of the first external gear 441 and the second external gear 442.

[0133] In the construction machine 1 of Modification 3, the buffer portion 5 can also be used to mitigate the impact transmitted to the speed reducer 4. In particular, the impact transmitted to the first member 41 and the speed reduction portion 45, which are part of the speed reducer 4, can be mitigated. In addition, the torque can be appropriately transmitted from the electric motor 3 to the speed reducer 4. Thus, in the construction machine 1 of Modification 3, the speed reducer 4 can also be used to decelerate and output the rotation input from the electric motor 3.

[0134] (Modification 4)

[0135] In the above-described embodiments and each modification, an example in which the main body portion 32 of the electric motor 3 is fixed to the mounting member 47 has been described. However, the fixing method of the electric motor 3 is not limited to this. Figure 7 It is a cross-sectional view showing a structural example around the electric motor 3 and the speed reducer 4 of the construction machine 1 equipped with the speed reducer 4 of Modification 4. In particular, Figure 7 It is a cross-sectional view obtained by cutting the construction machine 1 along the plane of the rotation axis LA of the rotation output from the speed reducer 4.

[0136] In Modification 4, the main body portion 32 of the electric motor 3 is fixed to the second member 42. In Figure 7 the construction machine 1 further has a connecting member 8 that connects the electric motor 3 and the second member 42 of the speed reducer 4. The connecting member 8 is fixed to the surface of the first side SA1 of the second member 42 by bolts 81. In addition, the main body portion 32 of the electric motor 3 is fixed to the surface of the first side SA1 of the connecting member 8 by bolts (not shown). Thus, the main body portion 32 of the electric motor 3 is disposed on the first side SA1 of the second member 42 and fixed to the second member 42.

[0137] A through-hole 82 that penetrates the connecting member 8 in the rotation axis direction DA is provided in the connecting member 8. The rotation shaft 31 of the electric motor 3 is inserted into the through-hole 82. The base end portion (the first side SA1 in the rotation axis direction DA) of the input shaft 46 of the speed reducer 4 on the electric motor 3 side is joined to the rotation shaft 31 of the electric motor 3 within the through-hole 82.

[0138] In Figure 7 the transmission gear 431 is fixed to one end on the second side SA2 in the rotation axis direction DA of the crankshaft 43. In addition, the transmission gear 431 is disposed on the second side SA2 in the rotation axis direction DA of the first external gear 441 and the second external gear 442. And the input shaft 46 is inserted into the first through-hole 44a of the first external gear 441 and the second external gear 442 and the through-hole 42h of the end plate portion 421. Thus, the drive gear 461 provided at the tip end portion 46a of the input shaft 46 meshes with the transmission gear 431 on the second side SA2 in the rotation axis direction DA of the first external gear 441 and the second external gear 442.

[0139] In Figure 7In this case, the mounting member 47 for fixedly accommodating the accommodating portion 48 is a member that forms a part of the construction machine 1. A part of the mounting member 47 is located on the first side SA1 in the rotational axis direction DA of the flange portion 49. Thus, the flange portion 49 faces a part of the mounting member 47. A threaded hole 474 that extends in the rotational axis direction DA and opens on the second side SA2 is provided in the portion of the mounting member 47 that faces the flange portion 49. In addition, the speed reducer 4 also has a fixing auxiliary member 9, and the fixing auxiliary member 9 is provided on the second side SA2 in the rotational axis direction DA of the first member 41 of the speed reducer 4. The fixing auxiliary member 9 entirely covers the speed reduction portion 45 and the first member 41 from the second side SA2 in the rotational axis direction DA. A part of the fixing auxiliary member 9 is located on the second side SA2 in the rotational axis direction DA of the flange portion 49. Thus, the flange portion 49 faces a part of the fixing auxiliary member 9. A through hole 91 that extends in the rotational axis direction DA and penetrates the fixing auxiliary member 9 is provided in the portion of the fixing auxiliary member 9 that faces the flange portion 49.

[0140] In Figure 7 this case, the mounting member 47 and the fixing auxiliary member 9 are fixed to the accommodating portion 48 by bolts 7. Specifically, as Figure 7 shown, by fastening the bolt 7 inserted through the through hole 91 and the through hole 41b to the threaded hole 474, the mounting member 47 and the fixing auxiliary member 9 can be fixed to the accommodating portion 48.

[0141] In Modification Example 4, the speed reducer 4 also has a buffer portion 5 that covers the inner wall 41c of the through hole 41b. In addition, the speed reducer 4 has a bushing 6 provided inside the buffer portion 5. And the bolt 7 passes through the buffer portion through hole 5a and passes through the bushing through hole 6a.

[0142] In Modification Example 4, the dimension w1 of the bushing 6 is also larger than the dimension w2 of the through hole 41b. In addition, in Modification Example 4, the dimension w1 of the bushing 6 is also larger than the dimension w3 of the flange portion 49. Thus, direct contact between the mounting member 47 and the first member 41 in the rotational axis direction DA can be suppressed. In addition, direct contact between the fixing auxiliary member 9 and the first member 41 in the rotational axis direction DA can be suppressed.

[0143] In the construction machine 1 of Modification Example 4, the buffer portion 5 can also be used to mitigate the impact transmitted to the speed reducer 4. In particular, the impact transmitted to the first member 41 and the speed reduction portion 45, which are parts of the speed reducer 4, can be mitigated. In addition, when the speed reducer 4 decelerates and outputs the rotation input from the electric motor 3, the torque from the electric motor 3 can be appropriately transmitted. Thus, in the construction machine 1 of Modification Example 4, the speed reducer 4 can also be used to decelerate and output the rotation input from the electric motor 3.

[0144] (Modification Example 5)

[0145] In the above-described embodiments and each modification, an example in which the through-hole 41b for fixing the accommodation portion 48 to the mounting member 47 is provided in the first member 41 has been described. However, the forms of the speed reducer 4 and the construction machine 1 are not limited to this. Figure 8 FIG. is a cross-sectional view showing a structural example around the motor 3 and the speed reducer 4 of the construction machine 1 equipped with the speed reducer 4 of Modification 5. In particular, Figure 8 FIG. is a cross-sectional view of the construction machine 1 cut along a plane passing through the rotation axis LA of the rotation output from the speed reducer 4.

[0146] In Modification 5, the through-hole 41b is not provided in the first member 41. And, the through-hole 47d for fixing the accommodation portion 48 to the mounting member 47 is provided in the mounting member 47. In this case, the mounting member 47 may also be a member regarded as a part of the speed reducer 4. The mounting member 47 may also be a member that forms a part of the construction machine 1 and is particularly large compared to the first member 41, the speed reduction portion 45, etc. of the speed reducer 4. In Figure 8 the mounting member 47 is a member regarded as a part of the speed reducer 4.

[0147] In the above-described embodiments and Modifications 1 to 4, the description of the through-hole 41b provided in the first member 41 can also be applied to the through-hole 47d provided in the mounting member 47 in Modification 5 as long as there is no contradiction.

[0148] Figure 8 The speed reducer 4 shown in FIG. further includes a buffer portion 5 having a cylindrical shape and covering the inner wall 47e of the through-hole 47d. The buffer portion 5 has a first portion 51 and a second portion 52 with different degrees of ease of deformation when subjected to a certain stress. In addition, the speed reducer 4 further includes a bushing 6 provided inside the buffer portion 5 and having a cylindrical shape. In the above-described embodiments and Modifications 1 to 4, the description of the buffer portion 5, the bushing 6, and the bolt 7 can also be applied to the buffer portion 5, the bushing 6, and the bolt 7 in Modification 5 as long as there is no contradiction.

[0149] In Modification 5, a threaded hole 491 extending in the rotation axis direction DA and opening on the second side SA2 is provided in a portion of the flange portion 49 facing the mounting member 47. In Modification 5, by screwing the bolt 7 through the through-hole 47d into the threaded hole 491 of the flange portion 49, the first member 41 (housing 41a) can be fixed to the mounting member 47, and the accommodation portion 48 can be fixed to the mounting member 47. The bolt 7 passes through the buffer portion through-hole 5a and also passes through the bushing through-hole 6a.

[0150] In Figure 8In this case, the dash-dotted line marked with the reference numeral LC represents an imaginary line indicating the axis LC of the through-hole 47d. The extending direction of the through-hole 47d (the extending direction of the axis LC of the through-hole 47d) is referred to as the axis direction DG. In addition, the direction perpendicular to the axis LC of the through-hole 47d is referred to as the radial direction DH. In Modification 5, the dimension w10 of the bushing 6 in the axis direction DG in which the through-hole 47d extends is larger than the dimension w11 of the through-hole 47d in the axis direction DG. Thereby, the bushing 6 can be arranged to protrude from the through-hole 47d on both sides of the through-hole 47d. Thereby, the mounting member 47 and the first member 41 are separated in the axis direction DG. Therefore, it is possible to suppress the impact from being directly transmitted from the mounting member 47 to the first member 41 in the axis direction DG.

[0151] Although not shown, the mounting member 47 of Modification 5 may also have a portion that faces the first member 41 in the radial direction DH. In this case, the mounting member 47 is arranged such that a gap is provided in the radial direction DH perpendicular to the axis LC of the through-hole 47d between the mounting member 47 and the first member 41. In particular, the mounting member 47 is arranged such that the width of the gap between the first member 41 and the mounting member 47 in the radial direction DH is larger than the width of the gap between the bushing 6 and the bolt 7 in the radial direction DH. Thereby, before the surfaces of the mounting member 47 and the first member 41 come into direct contact with each other in the radial direction DH, the impact can be mitigated by the buffer portion 5. Therefore, by the direct contact between the surface of the mounting member 47 and the surface of the first member 41 in the radial direction DH, it is possible to suppress a strong impact from being transmitted from the mounting member 47 to the first member 41.

[0152] In the construction machine 1 of Modification 5, the buffer portion 5 can also be used to mitigate the impact transmitted to the speed reducer 4. In particular, it is possible to mitigate the impact transmitted to the first member 41 and the speed reduction portion 45 which are part of the speed reducer 4. In addition, torque can be appropriately transmitted from the electric motor 3 to the speed reducer 4. Thereby, in the construction machine 1 of Modification 5, it is also possible to decelerate and output the rotation input from the electric motor 3 through the speed reducer 4.

[0153] In the above-described embodiments, a part composed of a plurality of objects may integrate the plurality of objects. Conversely, a part composed of one object may be divided into a plurality of objects. Whether integrated or not, as long as it is configured to achieve the object of the present invention, it is acceptable.

[0154] The embodiments of the present invention are not limited to the above-described respective embodiments, and also include various modifications that can be conceived by those skilled in the art. The effects of the present invention are not limited to the above content either. That is, various additions, changes, and partial deletions can be made without departing from the content defined in the claims and the conceptual ideas and gist of the present invention derived from their equivalents.

[0155] Reference Numeral Explanation

[0156] 1 Construction machinery

[0157] 2 Driving machine

[0158] 3 Electric motor

[0159] 31 Rotating shaft

[0160] 4 Reducer

[0161] 41 First component

[0162] 41b Through-hole

[0163] 42 Second component

[0164] 43 Crankshaft

[0165] 44 External gear

[0166] 45 Reduction part

[0167] 47 Mounting component

[0168] 48 Receiving part

[0169] 49 Flange part

[0170] 5 Buffer part

[0171] 51 First part

[0172] 52 Second part

[0173] 6 Bushing

[0174] 7 Bolt

Claims

1. A speed reducer, wherein, comprising: a deceleration section that decelerates the input rotation; a first member having a receiving portion that houses the deceleration section and provided with a through hole for fixing the receiving portion to a mounting member; and a buffer section having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress.

2. The speed reducer according to claim 1, wherein the speed reducer further comprises: a bushing disposed inside the buffer section and having a cylindrical shape.

3. The speed reducer according to claim 2, wherein the size of the bushing in the axial direction in which the through hole extends is larger than the size of the through hole in the axial direction.

4. The speed reducer according to claim 2, wherein the first member further has: a flange portion protruding from the receiving portion in a direction intersecting the axial direction in which the through hole extends and facing the mounting member, the through hole is provided in the flange portion, the size of the bushing in the axial direction is larger than the size of the flange portion in the axial direction.

5. The speed reducer according to claim 2, wherein the speed reducer further comprises: a bolt passing through the bushing to fix the receiving portion to the mounting member, the size of the bushing in the radial direction perpendicular to the axis of the through hole is larger than or equal to the size of the head of the bolt in the radial direction.

6. The speed reducer according to claim 1, wherein the speed reducer further comprises: a second member capable of relative rotation with respect to the first member, the first member has internal teeth, the deceleration section has: a crankshaft rotatably supported by the second member; and an external gear provided with a through hole for the crankshaft to pass through and having external teeth meshing with the internal teeth of the first member.

7. The speed reducer according to claim 2, wherein the speed reducer further comprises: the mounting member configured to leave a gap in the radial direction perpendicular to the axis of the through hole between the mounting member and the first member; and a bolt passing through the bushing and fixing the receiving portion to the mounting member, the width of the gap in the radial direction between the first member and the mounting member is larger than the width of the gap in the radial direction between the bushing and the bolt.

8. A speed reducer, wherein, comprising: a deceleration section that decelerates the input rotation; a first member having a receiving portion that houses the deceleration section; a mounting member that is a mounting member capable of fixing the receiving portion and provided with a through hole for fixing the receiving portion to the mounting member; and a buffer section having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion with different degrees of ease of deformation when subjected to a certain stress.

9. A construction machine, wherein, A speed reducer according to any one of claims 1 to 8.

10. A construction machine, wherein the construction machine has a speed reducer, the mounting member, and a bolt, the speed reducer has: a deceleration section that decelerates the input rotation; a first member having a receiving portion that houses the deceleration section and provided with a through hole for fixing the receiving portion to a mounting member; A buffer part, having a cylindrical shape, covering the inner wall of the through hole, and having a first part and a second part with different degrees of ease of deformation when subjected to a certain stress; and A bushing, disposed inside the buffer part and having a cylindrical shape, The mounting member is configured to leave a gap in the radial direction perpendicular to the axis of the through hole between it and the first member, A bolt, passing through the bushing to fix the accommodating part to the mounting member, The width of the gap in the radial direction between the first member and the mounting member is greater than the width of the gap in the radial direction between the bushing and the bolt.

11. A construction machine, wherein, Comprising: A speed reducer, having a speed reduction part for reducing the rotation input and a first member for accommodating the speed reduction part; A mounting member, which is a mounting member capable of fixing the accommodating part and is provided with a through hole for fixing the accommodating part to the mounting member; A buffer part, having a cylindrical shape, covering the inner wall of the through hole, and having a first part and a second part with different degrees of ease of deformation when subjected to a certain stress; A bushing, disposed inside the buffer part and having a cylindrical shape; and A bolt, passing through the bushing and fixing the accommodating part to the mounting member.

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