WO2024122156A1 - Speed reducer and construction machine - Google Patents

Abstract

[Problem] To mitigate impact transmitted to a speed reducer. [Solution] Provided is a speed reducer comprising a speed reduction unit which reduces the speed of input rotation, a first member which includes an accommodation unit for accommodating the speed reduction unit and is provided with a through-hole used to fix the accommodation unit to an attachment member, and a shock absorbing unit which has a tubular shape, covers an inner wall of the through-hole, and includes a first portion and a second portion different from each other in deformability upon application of certain stress.

Description

Reducer and construction machinery

The present invention relates to a reducer and a construction machine.

　Conventionally, devices that obtain propulsive force from the rotation output from an electric motor are known. For example, Patent Document 1 describes an electric linear actuator for obtaining propulsive force in a construction device such as a power shovel. In particular, Patent Document 1 describes the electric linear actuator being used to drive the boom, arm, bucket, etc. of the power shovel.

Furthermore, in devices that obtain propulsive force from the rotation output from an electric motor, technology is known for mitigating the impact on the device. For example, Patent Document 1 describes an impact mitigation device formed of an elastic body such as a spring that mitigates the impact force applied to the piston of an electric linear actuator.

International Publication No. 2013/114451

In some cases, a reducer is incorporated into a device that obtains propulsive force from the rotation output from the electric motor in order to slow down the rotation of the electric motor. In such cases, shocks may be transmitted to the reducer. In particular, when a device incorporating such a reducer is used to drive construction equipment, such as the boom, arm, or bucket of a power shovel, a relatively large shock may be transmitted to the reducer. It was also anticipated that a large shock would be transmitted to a part of the reducer, such as a part that has the function of slowing down the input rotation, and that this part would be damaged. For this reason, there was a need to alleviate the shock transmitted to the reducer, and in particular to that part of the reducer.

The present invention was made with these circumstances in mind, and aims to reduce the impact transmitted to the reducer.

A first aspect of the present disclosure is a rotational speed reducing unit that reduces the speed of an input rotation;
a first member having an accommodation portion that accommodates the reduction gear portion and having a through hole that is used for fixing the accommodation portion to a mounting member;
The reducer is provided with a buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion that differ in their ease of deformation when subjected to a certain stress.

A second aspect of the present disclosure may further include a bush having a cylindrical shape provided inside the buffer portion in the reducer according to the first aspect described above.

A third aspect of the present disclosure is a reducer according to the second aspect described above, in which the dimension of the bush in the axial direction in which the through hole extends may be greater than the dimension of the through hole in the axial direction.

A fourth aspect of the present disclosure is a reducer according to the second aspect or the third aspect described above, wherein the first member further has a flange portion that protrudes from the accommodating portion in a direction intersecting an axial direction in which the through hole extends and faces the mounting member,
The through hole is provided in the flange portion,
A dimension of the bush in the axial direction may be greater than a dimension of the flange portion in the axial direction.

A fifth aspect of the present disclosure is a reducer according to any one of the second to fourth aspects described above, further comprising a bolt that is passed through the bush and fixes the accommodation portion to the mounting member,
A dimension of the bush in a radial direction perpendicular to the axis of the through hole may be equal to or greater than a dimension of the head of the bolt in the radial direction.

A sixth aspect of the present disclosure is a reducer according to any one of the first to fifth aspects described above, further comprising a second member that is rotatable relative to the first member,
The first member has internal teeth;
The reduction section may include a crankshaft rotatably supported on the second member, and an external gear having a through hole through which the crankshaft passes and external teeth that mesh with internal teeth of the first member.

A seventh aspect of the present disclosure is a reducer according to each of the second aspect to the fifth aspect described above, further comprising the mounting member arranged so that a gap is formed between the mounting member and the first member in a radial direction perpendicular to the axis of the through hole;
a bolt that is passed through the bush and fixes the housing to the mounting member,
A width of a gap between the first member and the mounting member in the radial direction may be larger than a width of a gap between the bush and the bolt in the radial direction.

An eighth aspect of the present disclosure is a rotational speed reducing unit that reduces the speed of an input rotation;
A first member having a housing portion that houses the speed reducing portion;
a mounting member to which the accommodation portion is fixed, the mounting member having a through hole used for fixing the accommodation portion to the mounting member;
The insulating film may further include a buffer portion having a cylindrical shape, covering an inner wall of the through hole, and having a first portion and a second portion that differ in ease of deformation when subjected to a certain stress.

The ninth aspect of the present disclosure is a construction machine equipped with a reducer according to each of the first to eighth aspects described above.

A tenth aspect of the present disclosure is a reducer including: a speed reducer section that reduces the speed of an input rotation; a first member having a housing section that houses the speed reducer section and having a through hole used for fixing the housing section to a mounting member; a buffer section that has a cylindrical shape, covers an inner wall of the through hole, and has a first part and a second part that differ in their ease of deformation when subjected to a certain stress; and a bushing that is provided inside the buffer section and has a cylindrical shape;
The mounting member is disposed so as to have a gap between the mounting member and the first member in a radial direction perpendicular to an axis of the through hole;
a bolt that is passed through the bush and fixes the housing portion to the mounting member,
In the construction machine, the width of a gap between the first member and the mounting member in the radial direction is larger than the width of a gap between the bush and the bolt in the radial direction.

An eleventh aspect of the present disclosure is a reducer including a first member having a reduction section that reduces the speed of an input rotation and a housing section that houses the reduction section;
a mounting member to which the accommodation portion is fixed, the mounting member having a through hole used for fixing the accommodation portion to the mounting member;
a buffer portion having a cylindrical shape, covering an inner wall of the through hole, and having a first portion and a second portion that differ in ease of deformation when subjected to a certain stress;
A bush provided inside the buffer portion and having a cylindrical shape;
A bolt may be passed through the bush to fix the housing portion to the mounting member.

The present invention makes it possible to transmit the required torque while mitigating the impact transmitted to the reducer.

1 is a cross-sectional view of a construction machine according to an embodiment. FIG. 2 is a cross-sectional view of a reducer according to an embodiment. 2 is an enlarged cross-sectional view showing a portion surrounded by a dashed line and indicated by reference symbol III in FIG. 1; FIG. FIG. 4 is an enlarged cross-sectional view of a construction machine according to a first modified example. FIG. 11 is a cross-sectional view of a construction machine according to a second modified example. FIG. 11 is a cross-sectional view of a construction machine according to a third modified example. FIG. 11 is a cross-sectional view of a construction machine according to a fourth modified example. FIG. 13 is a cross-sectional view of a construction machine according to a fifth modified example.

This embodiment will be described in detail with reference to the drawings. First, a construction machine 1 incorporating a reducer 4 according to this embodiment will be described. FIG. 1 is a cross-sectional view showing an example of the configuration of the vicinity of the reducer 4 of a construction machine 1 incorporating the reducer 4. In particular, FIG. 1 is a cross-sectional view of the construction machine 1 incorporating the reducer 4, cut along a plane passing through the rotation axis LA of the rotation output by the reducer 4. FIG. 2 is a cross-sectional view of the reducer 4 cut along line II-II in FIG. 1.

The direction in which the rotation axis LA of the rotation output by the reducer 4 extends is called the rotation axis direction DA. In the rotation axis direction DA, the side on which the base plate portion 422 of the second member 42 described later is located is called the first side SA1, based on the end plate portion 421 of the second member 42 of the reducer 4 described later. Also, in the rotation axis direction DA, the side opposite the side on which the base plate portion 422 of the second member 42 is located is called the second side SA2, based on the end plate portion 421 of the second member 42. In FIG. 1, the mounting member 47 is located on the second side SA2 in the rotation axis direction DA of the reducer 4. Also, the direction circumnavigating 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 that can be drawn to the rotation axis LA extends.

The construction machine 1 is equipped with a reduction gear 4 according to this embodiment. The construction machine 1 is further equipped with an electric motor 3. The reduction gear 4 reduces the speed of the rotation input from the electric motor 3.

In this embodiment, the electric motor 3 is a general electric motor. The electric motor 3 has a main body 32 and a rotating shaft 31 that rotates relative to the main body 32. In FIG. 1, the main body 32 of the electric motor 3 is fixed to a mounting member 47 described later. Although not shown, the electric motor 3 is fixed to the surface of the second side SA2 of the mounting member 47 by being fixed to the mounting member 47 with a bolt. As shown in FIG. 1, the mounting member 47 has a through hole 471 that penetrates the mounting member 47 in the rotation axis direction DA. The rotating shaft 31 of the electric motor 3 is inserted into the through hole 471. The rotating shaft 31 protrudes toward the first side SA1 and extends in the rotation axis direction DA. In FIG. 1, the rotation axis about which the rotating shaft 31 rotates coincides with the rotation axis LA of the rotation output by the reducer 4.

The reducer 4 will be described. The reducer 4 is disposed on the first side SA1 in the rotation axis direction DA of the electric motor 3. The reducer 4 includes a reduction section 45, a first member 41, and a buffer section 5. The reduction section 45 reduces the speed of the input rotation. The first member 41 has a housing section 48 that houses the reduction section 45, and the first member 41 is provided with a through hole 41b that is used to fix the housing section 48 to the mounting member 47 described later. The buffer section 5 has a cylindrical shape and covers the inner wall 41c of the through hole 41b. As described later, the buffer section 5 has a first part 51 and a second part 52 that differ in their ease of deformation when subjected to a certain stress. The reducer 4 of this embodiment also includes a bush 6, a bolt 7, a second member 42, and a mounting member 47 described later. Note that in FIG. 1, the shapes of the first part 51 and the second part 52 are omitted, and only the outer shape of the buffer section 5 is shown. Also, in Figure 2, the buffer section 5, bushing 6, and bolt 7 are not shown.

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

In this embodiment, the first member 41 has internal teeth 412. The reduction gear unit 45 has a crankshaft 43 rotatably supported by the second member 42, and an external gear 44 having external teeth 441a, 442a and a through hole 44d through which the crankshaft 43 passes. In the reduction gear unit 45, the crankshaft 43 to which rotation is input eccentrically oscillates the external gear 44. The external teeth 441a, 442a of the external gear 44 mesh with the internal teeth 412 of the first member 41. The external teeth 441a, 442a of the eccentrically oscillated external gear 44 mesh with the internal teeth 412 of the first member 41, causing the first member 41 and the second member 42 to rotate relative to each other.

In this embodiment, the external gear 44 has a through hole 44d through which the crankshaft 43 passes.

In this embodiment, the reduction gear unit 45 includes a plurality of crankshafts 43. The plurality of crankshafts 43 extend through the through holes 44d of the external gear 44. The external gear 44 is provided with a plurality of through holes 44d, and each of the plurality of crankshafts 43 extends through each of the plurality of through holes 44d.

In this embodiment, the reducer 4 has a cylindrical case 41a as the first member 41. The reducer 4 also has a carrier 42a as the second member 42, which is arranged on the inside of the case 41a in the rotation axis radial direction DC (the side closer to the rotation axis LA in the rotation axis radial direction DC). The reducer 4 also has an input shaft 46 that applies a driving force to rotate the carrier 42a. The mounting member 47 of the reducer 4 has a through hole 471 to which the electric motor 3 is fixed. The mounting member 47 has a cylindrical shape.

The first member 41 (case 41a) has a housing portion 48 that houses the crankshaft 43 and the external gear 44, which are the reduction gear portion 45. In this embodiment, the housing portion 48 is a part of the case 41a that has a cylindrical shape. The first member 41 (case 41a) also has a through hole 41b that is used to fix the housing portion 48 to the mounting member 47. The through hole 41b extends in the rotation axis direction DA. The case 41a is fixed to the mounting member 47 by passing the bolt 7 described later through the through hole 41b and screwing it to the mounting member 47, and the housing portion 48 is fixed to the mounting member 47. The case 41a is fixed to the mounting member 47, and the electric motor 3 is fixed to the mounting member 47, so that the electric motor 3 is fixed to the case 41a via the mounting member 47.

The inner circumferential surface of the case 41a is provided with internal teeth 412. The internal teeth 412 are pin-shaped (cylindrical) teeth provided on the inner circumferential surface of the case 41a. In particular, the first member 41 has, as the internal teeth 412, internal tooth pins 412a fitted into pin grooves 412b. A plurality of internal teeth 412 are arranged at equal intervals in the circumferential direction DB of the rotation axis.

The carrier 42a is rotatably supported on the case 41a by a pair of main bearings 42j spaced apart in the direction of the rotation axis DA. The main bearings 42j are, for example, angular ball bearings. The carrier 42a is arranged coaxially with the case 41a and the rotation axis LA.

The carrier 42a includes a disk-shaped end plate portion 421 disposed on the second side SA2 in the direction of the rotation axis DA, a disk-shaped base plate portion 422 disposed on the first side SA1 in the direction of the rotation axis DA, and three pillar portions 423 integrally formed with the base plate portion 422 and protruding from the base plate portion 422 toward the end plate portion 421. The pillar portions 423 shown in FIG. 2 have a columnar shape such that a cross section perpendicular to the direction of the rotation axis DA is a substantially triangular shape with rounded corners. The pillar portions 423 are disposed at equal intervals in the circumferential direction DB of the rotation axis. The pillar portions 423 and the end plate portions 421 are fixed to each other by fastening them to each other with the bolts 42b with the tip surface of the pillar portion 423 overlapping the end plate portion 421. In this state, a space having a predetermined width in the direction of the rotation axis DA is formed between the base plate portion 422 and the end plate portion 421.

The column portion 423 has a bolt fastening hole 42c into which the bolt 42b is fastened. The end plate portion 421 has a bolt insertion hole 42d into which the bolt 42b is inserted. The bolt 42b is inserted into the bolt insertion hole 42d from the opposite side of the end plate portion 421 to the column portion 423 and fastened to the bolt fastening hole 42c of the column portion 423. A pin 42e is provided on the inside of the bolt 42b in the rotation axis radial direction DC to position the end plate portion 421 with respect to the base plate portion 422. The pin 42e is arranged so as to straddle the column portion 423 and the end plate portion 421. The column portion 423 does not have to be formed integrally with the base plate portion 422. In this case, the column portion 423 is fastened to the base plate portion 422. The column portion 423 is not limited to a columnar shape in which the cross section perpendicular to the rotation axis direction DA is a substantially triangular shape with rounded corners. The pillar portion 423 may form a space having a predetermined width in the rotation axis direction DA between the base plate portion 422 and the end plate portion 421. The pillar portion 423 may be cylindrical.

The end plate portion 421 and the base plate portion 422 each have a plurality of holes 42f, 42g (for example, three in this embodiment) into which the crankshaft 43 of the reduction gear portion 45 is inserted. The holes 42f, 42g are arranged at equal intervals in the circumferential direction DB of the rotation axis. Furthermore, through holes 42h, 42i that penetrate in the rotation axis direction DA are formed in the center of the end plate portion 421 and the base plate portion 422 in the radial direction DC of the rotation axis. The input shaft 46 is inserted into these through holes 42h, 42i. The input shaft 46 is arranged coaxially with the case 41a and the rotation axis LA.

The base end of the input shaft 46 on the electric motor 3 side (second side SA2 in the rotation axis direction DA) is connected to the rotating shaft 31 of the electric motor 3. This causes the input shaft 46 to rotate integrally with the rotating shaft 31. The tip 46a of the input shaft 46 on the side opposite the electric motor 3 (first side SA1 in the rotation axis direction DA) is disposed within the through hole 42i of the base plate portion 422. A drive gear 461 having external teeth is integrally provided on the tip 46a of the input shaft 46.

The reduction gear unit 45 rotates the carrier 42a at a rotation speed that is reduced by a predetermined ratio relative to the rotation speed of the input shaft 46. The reduction gear unit 45 has a plurality of (e.g., three in this embodiment) transmission gears 431 that mesh with the drive gear 461, and a plurality of (e.g., three in this embodiment) crankshafts 43 with one end fixed to the transmission gears 431. The transmission gears 431 are fixed to one end of the first side SA1 in the rotation axis direction DA of the crankshafts 43. In this embodiment, the reduction gear unit 45 also has, as the external gears 44, a first external gear 441 and a second external gear 442 that oscillate and rotate in conjunction with the rotation of the crankshafts 43.

Since a 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. In other words, the crankshaft 43 rotates about a rotation axis that is parallel to the rotation axis LA of the rotation output by the reduction gear 4. The crankshaft 43 is rotatably supported by the end plate portion 421 via the first crank bearing 43a. The crankshaft 43 is rotatably supported by the base plate portion 422 via the second crank bearing 43b. The first crank bearing 43a and the second crank bearing 43b are, for example, tapered roller bearings.

A first eccentric portion 43c and a second eccentric portion 43d are formed in the center of the crankshaft 43 in the rotational axis direction DA, and are eccentric from the axis of the crankshaft 43. The first eccentric portion 43c and the second eccentric portion 43d are disposed adjacent to each other in the rotational axis direction DA between the first crank bearing 43a and the second crank bearing 43b. The first eccentric portion 43c is adjacent to the first crank bearing 43a. The second eccentric portion 43d is adjacent to the second crank bearing 43b. The first eccentric portion 43c and the second eccentric portion 43d are also out of phase with each other.

Such a crankshaft 43 is inserted into each of the holes 42f, 42g of the end plate portion 421 and the base plate portion 422. That is, the crankshaft 43 is also disposed at equal intervals in the circumferential direction DB of the rotation axis, just like each of the holes 42f, 42g.

A first roller bearing 43e is attached to the first eccentric portion 43c of the crankshaft 43. A second roller bearing 43f is attached to the second eccentric portion 43d. The first roller bearing 43e is, for example, a cylindrical roller bearing. The first external gear 441 and the second external gear 442 are oscillatingly rotated via the roller bearings 43e, 43f as the crankshaft 43 rotates.

The first external gear 441 and the second external gear 442 are disposed in the space between the base plate portion 422 and the end plate portion 421 of the carrier 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 case 41a. The first external gear 441 and the second external gear 442 are formed with 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. 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.

The first eccentric portion 43c and the first roller bearing 43e of the crankshaft 43 are inserted into the through hole 44d of the first external gear 441. The second eccentric portion 43d and the second roller bearing 43f of the crankshaft 43 are inserted into the through hole 44d of the second external gear 442. As a result, as the first eccentric portion 43c and the second eccentric portion 43d oscillate and rotate due to the rotation of the crankshaft 43, the first external gear 441 and the second external gear 442 oscillate and rotate while meshing with the internal teeth 412 of the case 41a.

The operation of the reducer 4 will now be explained. When the electric motor 3 is driven, the input shaft 46 is driven integrally with the rotating shaft 31. Then, the rotation of the input shaft 46 rotates the transmission gear 431 via the drive gear 461. As a result, the crankshaft 43 rotates integrally with the transmission gear 431.

When the crankshaft 43 rotates, the first external gear 441 rotates while meshing with the internal teeth 412 in accordance with the oscillation of the first eccentric portion 43c. Also, the second external gear 442 rotates while meshing with the internal teeth 412 in accordance with the oscillation of the second eccentric portion 43d. In other words, the crankshaft 43 rotates about a rotation axis parallel to the rotation axis LA of the rotation output by the reducer 4, and revolves around the rotation axis LA. In this way, the first external gear 441 and the second external gear 442 are driven by the rotation of the crankshaft 43.

When the first external gear 441 and the second external gear 442 are driven, the second member 42 (carrier 42a) whose column portion 423 is 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. As a result, the carrier 42a rotates at a reduced rotation speed relative to the case 41a, which is fixed to the electric motor 3 via the mounting member 47, compared to the input shaft 46. As a result, the speed reducer 4 can slow down the rotation of the electric motor 3.

Although the above description has been given of the reducer 4 in which the reduction section 45 has a crankshaft 43 and an external gear 44, the form of the reducer 4 is not limited to this. The reduction section 45 of the reducer 4 may have a planetary gear rotatably supported on the second member 42, and the planetary gear to which rotation is input may mesh with the internal teeth 412 of the first member 41, causing the first member 41 and the second member 42 to rotate relative to each other. In other words, the reducer 4 may be a planetary gear reducer.

Details of the through hole 41b, as well as the buffer section 5 and the bush 6 will be described. In this embodiment, the first member 41 is provided with a plurality of through holes 41b. FIG. 3 is an enlarged cross-sectional view showing an enlarged view of the portion surrounded by the two-dot chain line marked with the symbol III in FIG. 1. The dashed line marked with the symbol LB in FIG. 1 is an imaginary line showing the axis LB of the through hole 41b. The axis LB is an imaginary line passing through the center of gravity of the cross section of the through hole 41b. For example, when 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 direction in which the through hole 41b extends (the direction in which the axis LB of the through hole 41b extends) is also referred to as the axial direction DD. In this embodiment, the axial direction DD in which the through hole 41b extends is parallel to the rotational axis direction DA in which the rotational axis LA of the rotation output by the reducer 4 extends. In the axial direction DD, the side on which the mounting member 47 is located with respect to the through hole 41b is referred to as the first side SD1. In addition, in the axial direction DD, the side opposite the side on which the mounting member 47 is located with respect to the through hole 41b is referred to as the second side SD2. In addition, the direction going 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 direction in which a perpendicular line that can be drawn to the axis LB extends.

In this embodiment, the multiple through holes 41b are arranged in a line in the rotation axis circumferential direction DB that orbits the rotation axis LA. The multiple through holes 41b surround the accommodation section 48 from the outside in the rotation axis radial direction DC that is perpendicular to the rotation axis LA. The number of through holes 41b can be changed as appropriate depending on the magnitude of torque that is required to be transmitted when transmitting torque from the electric motor 3 to the reducer 4. In this case, the buffer section 5, which will be described later, is provided in each of the multiple through holes 41b.

In this embodiment, the first member 41 further has a flange portion 49 that protrudes from the accommodating portion 48 in a direction intersecting the axial direction DD in which the through hole 41b extends, and faces the mounting member 47. In this embodiment, the flange portion 49 protrudes outward from the accommodating portion 48 in the radial direction DC of the rotation axis. The flange portion 49 also extends in the circumferential direction DB of the rotation axis. As a result, the flange portion 49 surrounds the accommodating portion 48 from the outside in the radial direction DC of the rotation axis. The through hole 41b is provided in the flange portion 49. In this embodiment, the mounting member 47 has a mounting surface 47a in which a screw hole 47b is provided. 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. In addition, the surface of the flange portion 49 that is located on the opposite side to the first surface 49a 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 this embodiment, the first surface 49a, the second surface 49b, and the mounting surface 47a are surfaces perpendicular to the axial direction DD. The multiple through holes 41b are provided so as to open in the first surface 49a and the second surface 49b of the flange portion 49.

The reducer 4 includes a buffer section 5 having a cylindrical shape and covering the inner wall 41c of the through hole 41b. The buffer section 5 is a portion that buffers the impact transmitted from the mounting member 47 to the first member 41 when the mounting member 47 receives an impact. In this embodiment, the buffer section 5 has a substantially cylindrical shape. The buffer section 5 has a cylindrical shape and thus has a buffer section through hole 5a extending in the axial direction DD. The bolt 7, which will be described later, is passed through the buffer section through hole 5a. In this embodiment, the buffer section 5 is continuously in close contact with the inner wall 41c of the through hole 41b in the circumferential direction DE. The buffer section 5 is fixed to the inner wall 41c of the through hole 41b. The buffer section 5 is fixed to the inner wall 41c of the through hole 41b by being bonded to the inner wall 41c of the through hole 41b using, for example, an adhesive.

The buffer section 5 has a first portion 51 and a second portion 52 that differ in their ease of deformation when subjected to a certain stress. Each of the first portion 51 and the second portion 52 has a tubular shape. In this embodiment, the first portion 51 has a substantially cylindrical shape. The second portion 52 has a cylindrical shape. The second portion 52 is located inward in the radial direction DF (closer to the axis LB in the radial direction DF) than the first portion 51. The first portion 51 is continuously in close contact with the inner wall 41c of the through hole 41b in the circumferential direction DE. The second portion 52 is continuously in close contact with 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 by being bonded to the inner wall 51a of the first portion 51 using, for example, an adhesive.

In this 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 magnitude 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 magnitude of elongation of the first part 51 and the second part 52 when subjected to a certain tensile stress is measured, and if the magnitude of elongation of the second part 52 is greater than that of the first part 51, it can be considered that the second part 52 is more likely to deform than the first part 51 when subjected to a certain stress. The magnitude 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. In accordance with JIS K6251:2017, test pieces having the same shape are prepared for the first part 51 and the second part 52, and a tensile tester is prepared. Then, the test piece is pulled using the tensile tester so that a certain tensile stress is applied to the test piece. The magnitude of elongation of the test piece is then measured when the test piece is pulled. The measured magnitudes of elongation of the test piece are then compared for the first portion 51 and the second portion 52.

Also, as an index of the ease of deformation when subjected to a certain stress, the degree 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 may be used. That is, the degree of shrinkage of the first part 51 and the second part 52 when subjected to a certain compressive stress is measured, and if the degree of shrinkage of the second part 52 is greater than that of the first part 51, it can be considered that the second part 52 is more likely to deform when subjected to a certain stress than the first part 51. The degree 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. In accordance with JIS K6254:2016, test pieces having the same shape are prepared for the first part 51 and the second part 52, and a compression tester is prepared. Then, the test piece is pulled using the compression tester so that a certain compressive stress is applied to the test piece. Then, the degree of shrinkage of the test piece when the test piece is pulled is measured. The magnitude of shrinkage measured for the first portion 51 and the second portion 52 of the test specimen is then compared.

In this embodiment, the buffer section 5 has a first flange section 53 overlapping the first surface 49a of the flange section 49 and a second flange section 54 overlapping the second surface 49b of the flange section 49. The buffer section 5 has a cylindrical buffer section main body section 55, a first flange section 53, and a second flange section 54. The first flange section 53 is connected to the end of the buffer section main body section 55 on the first side SD1 in the axial direction DD. The second flange section 54 is connected to the end of the buffer section main body section 55 on the second side SD2 in the axial direction DD. Each of the first flange section 53 and the second flange section 54 protrudes outward in the radial direction DF from the buffer section main body section 55. The first flange section 53 is in contact with the first surface 49a of the flange section 49. The second flange section 54 is in contact with the second surface 49b of the flange section 49.

In this embodiment, the first flange portion 53 and the second flange portion 54 are formed by the first portion 51, which is located radially outward from the second portion 52 in the radial direction DF (the side farther from the axis LB in the radial direction DF) and is less likely to deform than the second portion 52 when subjected to a certain stress.

In this embodiment, the first portion 51 and the second portion 52 are more likely to deform when subjected to a certain stress than the mounting member 47, the first member 41, the bolt 7, and the bushing 6 described below. The ease with which the first portion 51 and the second portion 52 deform when subjected to a certain stress may be ensured by selecting the material 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 material of the first portion 51 and the second portion 52 is not particularly limited as long as it can reduce the impact transmitted from the mounting member 47 to the first member 41. The material of the first portion 51 and the second portion 52 may be resin or metal. The material of the first portion 51 and the second portion 52 is, for example, rubber.

The buffer portion 5 has a first flange portion 53 and a second flange portion 54, which prevents the buffer portion 5 from slipping out of the through hole 41b.

The reducer 4 further includes a bush 6 having a cylindrical shape provided inside the buffer section 5. In this embodiment, the bush 6 has a cylindrical shape. The bush 6 has a cylindrical shape, and thus has a bush through hole 6a extending in the axial direction DD. A bolt 7, which will be described later, is passed through the bush through hole 6a. In this embodiment, the bush 6 is continuously in close contact with the inner wall 5b of the buffer section through hole 5a in the circumferential direction DE. The bush 6 is fixed to the inner wall 5b of the buffer section through hole 5a. The bush 6 is fixed to the inner wall 5b of the buffer section through hole 5a by being bonded to the inner wall 5b of the buffer section through hole 5a using, for example, an adhesive. The end of the bush 6 on the first side SD1 in the axial direction DD is referred to as the first end 6b. The end of the bush 6 on the second side SD2 in the axial direction DD is referred to as the second end 6c.

The material of the bushing 6 is selected so that it can be fixed to the mounting member 47 using the bolts 7. In this embodiment, the material of the bushing 6 is metal. As an example, the material of the bushing 6 is iron.

In this embodiment, the dimension w1 of the bush 6 in the axial direction DD in which the through hole 41b extends is greater than the dimension w2 of the through hole 41b in the axial direction DD. This allows the bush 6 to be positioned so that it protrudes from the through hole 41b on both sides of the through hole 41b.

In addition, in this embodiment, the dimension w1 of the bush 6 in the axial direction DD is greater than the dimension w3 of the flange portion 49 in the axial direction DD. This allows the first end 6b of the bush 6 to be positioned on the first side SD1 in the axial direction DD relative to the first surface 49a of the flange portion 49, and the second end 6c of the bush 6 to be positioned on the second side SD2 in the axial direction DD relative to the second surface 49b of the flange portion 49.

In this embodiment, the reducer 4 further includes a bolt 7 that is passed through the bush 6 to fix the accommodating portion 48 to the mounting member 47. In this embodiment, the bolt 7 has a shaft portion 7a with an external thread 7b and a head portion 7c provided at one end of the shaft portion 7a. The dimension w4 of the bush through hole 6a in the radial direction DF perpendicular to the axis LB of the through hole 41b is equal to or greater than the dimension w5 of the shaft portion 7a in the radial direction DF. The dimension w4 of the bush through hole 6a in the radial direction DF is smaller than the dimension w6 of the head portion 7c in the radial direction DF. For this reason, the shaft portion 7a is passed through the bush through hole 6a, and the end of the shaft portion 7a opposite to the side where the head portion 7c is provided is screwed into the screw hole 47b of the mounting member 47, whereby the bush 6 can be sandwiched between the head portion 7c and the mounting member 47. The bush 6 is fixed to the mounting member 47 by being sandwiched between the head portion 7c and the mounting member 47. In this embodiment, the bush 6 is fixed to the inner wall 5b of the buffer through hole 5a, and the buffer 5 is fixed to the inner wall 41c of the through hole 41b. Therefore, by fixing the bush 6 to the mounting member 47 with the bolt 7, the first member 41 including the storage portion 48 is fixed to the mounting member 47 via the bush 6 and the buffer 5.

Furthermore, the dimension w7 of the bushing 6 in the radial direction DF perpendicular to the axis LB of the through hole 41b is equal to or greater than the dimension w6 of the head 7c of the bolt 7 in the radial direction DF.

In addition, in this embodiment, the reducer 4 further includes an attachment member 47 that is arranged so as to leave a gap between the first member 41 and the attachment member 47 in the radial direction DF perpendicular to the axis LB of the through hole 41b. That is, in this embodiment, the attachment member 47 is a part of the reducer 4. As described above, the attachment member 47 in this embodiment is a member to which the electric motor 3 is fixed.

The first member 41 and the mounting member 47 may have faces that face each other in the radial direction DF. In FIG. 3, face 41d of the first member 41 and face 47c of the mounting member 47 face each other in the radial direction DF. Here, in this embodiment, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is larger than the width w9 of the gap between the bush 6 and the bolt 7 in the radial direction DF.

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 when considering the distance between the first member 41 and the mounting member 47 in all directions parallel to a plane perpendicular to the axis LB of the through hole 41b. Also, the width w9 of the gap between the bush 6 and the bolt 7 in the radial direction DF is the gap between the bush 6 and the bolt 7 in the radial direction DF when the bolt 7 is positioned relative to the through hole 41b so that the axis of the bolt 7 coincides with the axis LB of the through hole 41b.

As described above, the reducer 4 of this embodiment includes the first member 41 having the reduction unit 45 that reduces the input rotation, the accommodation unit 48 that accommodates the reduction unit 45, and the through hole 41b used to fix the accommodation unit 48 to the mounting member 47, and the buffer unit 5 having a cylindrical shape that covers the inner wall 41c of the through hole 41b and has a first part 51 and a second part 52 that differ in ease of deformation when subjected to a certain stress. The number of through holes 41b is determined so that a torque of a magnitude required to be transmitted can be transmitted when transmitting torque from the electric motor 3 to the reducer 4, and the buffer unit 5 is provided in each of the multiple through holes 41b. The reducer 4 provides the following effects. It is considered that the mounting member 47 will receive an impact. For example, when the reducer 4 is incorporated in a construction machine 1 such as a power shovel, it is considered that the mounting member 47 will receive an impact when an impact received from the outside of the construction machine 1 is transmitted to the mounting member 47. At this time, it is considered that the impact received by the mounting member 47 is also transmitted to the bolt 7 that is passed through the through hole 41b and screwed into the screw hole 47b of the mounting member 47. In this case, it is considered that the bolt 7 moves in the radial direction DF due to the impact received, and transmits the impact to the first member 41. In the case where the reducer 4 further includes a bush 6, it is considered that the bolt 7 and the bush 6 move in the radial direction DF due to the impact received by the bolt 7, and the impact received by the bolt 7 is transmitted to the first member 41 via the bush 6. Here, the reducer 4 of this embodiment includes a buffer section 5 that has a cylindrical shape and covers the inner wall 41c of the through hole 41b. The buffer section 5 is disposed 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 to transmit the impact to the first member 41, the buffer section 5 can mitigate the impact transmitted from the bolt 7 to the first member 41. As a result, the buffer section 5 can mitigate the impact transmitted from the bolt 7 to the reduction section 45 via the first member 41. As described above, the buffer section 5 can reduce the impact transmitted to the reducer 4, particularly to the first member 41 and the reduction section 45, which are part of the reducer 4.

In this embodiment, the buffer section 5 has a first portion 51 and a second portion 52 that differ in ease of deformation when subjected to a certain stress. In this embodiment, the second portion 52 is more likely to deform than the first portion 51 when subjected to a certain stress. The first portion 51 and the second portion 52 each have a cylindrical shape. By having the buffer section 5 have the first portion 51 and the second portion 52, the following effects can be obtained. When the bolt 7 moves in the radial direction DF to transmit an impact to the first member 41, the impact can be effectively absorbed by the easily deformed second portion 52. It is also possible that the impact from the bolt 7 is particularly large, and the second portion 52 is deformed to the extent that there is no room for further deformation. In this case, too, the impact can be absorbed by the first portion 51, which is less likely to deform than the second portion 52.

In addition, by having the buffer section 5 have the first part 51 and the second part 52, the following effect can be obtained. Compared to when the buffer section 5 is formed only of the second part 52, which is more easily deformed than the first part 51, the buffer section 5 is less likely to deform. This makes it possible to suppress the escape of the input rotational force by the buffer section 5 when rotation is input to the reducer 4. In particular, when rotation is input to the reducer 4 from the electric motor 3 fixed to the mounting member 47 as in this embodiment, the escape of the rotational force input from the electric motor 3 due to the buffer section 5 can be suppressed. In particular, the first part 51, which is less likely to deform than the second part 52, can be set to be less likely to deform due to the force that is normally applied when rotation is input to the reducer 4. In this case, even if the second part 52 is deformed when rotation is input to the reducer 4, the deformation of the first part 51 is suppressed. By suppressing deformation of the first portion 51 when rotation is input to the reducer 4, the amount of rotational force lost by the buffer portion 5 can be reduced, and torque can be appropriately transmitted from the electric motor 3 to the reducer 4. As a result, rotation can be efficiently input to the reducer 4 while providing the buffer portion 5.

As described above, according to the buffer section 5 of this embodiment, the second portion 52 can be set as a portion that deforms more than the first portion 51 and largely absorbs the impact when the bolt 7 moves in the radial direction DF to transmit an impact to the first member 41. Furthermore, the first portion 51 can be set as a portion that further absorbs the impact when the bolt 7 moves in the radial direction DF to transmit an impact to the first member 41 is particularly large and the second portion 52 is completely deformed. Furthermore, the first portion 51 can be set to be less likely to deform due to the force that is normally applied when rotation is input to the reducer 4. In this way, the buffer section 5 is provided in the reducer 4 to absorb the impact transmitted from the bolt 7 to the first member 41 in the radial direction DF, while increasing the efficiency with which rotation is input to the reducer 4 and increasing the efficiency with which the reducer 4 outputs reduced rotation.

The reducer 4 of this embodiment further includes a bush 6 having a cylindrical shape provided inside the buffer section 5. As a result, by fixing the bush 6 to the buffer section 5, fixing the buffer section 5 to the first member 41, and fixing the bush 6 to the mounting member 47 with the bolt 7, the first member 41 having the accommodation section 48 can be stably fixed to the mounting member 47 via the bush 6 and the buffer section 5.

Furthermore, in this embodiment, the dimension w1 of the bushing 6 in the axial direction DD in which the through hole 41b extends is greater than the dimension w2 of the through hole 41b in the axial direction DD. This allows the bushing 6 to be positioned so that it protrudes from the through hole 41b on both sides of the through hole 41b. Also, in this embodiment, the dimension w1 of the bushing 6 in the axial direction DD is greater than the dimension w3 of the flange portion 49 in the axial direction DD. This allows the first end portion 6b of the bushing 6 to be positioned on the first side SD1 in the axial direction DD relative to the first surface 49a of the flange portion 49, and the second end portion 6c of the bushing 6 to be positioned on the second side SD2 in the axial direction DD relative to the second surface 49b of the flange portion 49.

By arranging the bush 6 in this manner, the following effect is obtained. The bush 6 protrudes from the through hole 41b on the first side SD1 of the through hole 41b, and the first end 6b of the bush 6 is arranged on the first side SD1 in the axial direction DD further than the first surface 49a of the flange portion 49, so that the first end 6b of the bush 6 comes into contact with the mounting surface 47a of the mounting member 47. This separates the mounting surface 47a of the mounting member 47 from the surface facing the mounting surface 47a of the first member 41 in the axial direction DD (the first surface 49a of the flange portion 49). This makes it possible to prevent the mounting member 47 and the first member 41 from coming into direct contact in the axial direction DD, and to prevent a direct impact from being transmitted from the mounting member 47 to the first member 41 in the axial direction DD. In addition, the bush 6 protrudes from the through hole 41b on the second side SD2 of the through hole 41b, and the second end 6c of the bush 6 is disposed on the second side SD2 in the axial direction DD, further than the second surface 49b of the flange portion 49, thereby achieving the following effect: When the bush 6 is sandwiched between the head 7c of the bolt 7 and the mounting member 47 and the bush 6 is fixed to the mounting member 47, the head 7c of the bolt 7 is prevented from contacting the first member 41. This makes it possible to prevent an impact from being directly transmitted from the head 7c of the bolt 7 to the first member 41.

The reducer 4 of this embodiment further includes a bolt 7 that is passed through the bush 6 and fixes the housing portion 48 to the mounting member 47. The dimension w7 of the bush 6 in the radial direction DF perpendicular to the axis LB of the through hole 41b is equal to or greater than the dimension w6 of the head 7c of the bolt 7 in the radial direction DF. This also prevents the head 7c of the bolt 7 from contacting the first member 41 when the bush 6 is sandwiched between the head 7c of the bolt 7 and the mounting member 47 and the bush 6 is fixed to the mounting member 47. This prevents the head 7c of the bolt 7 from directly transmitting an impact to the first member 41. In addition, when the bush 6 is sandwiched between the head 7c of the bolt 7 and the mounting member 47 and the bush 6 is fixed to the mounting member 47, the area where the head 7c contacts the bush 6 can be secured. This allows the bush 6 to be stably fixed to the mounting member 47, increasing the efficiency with which rotation is input from the electric motor 3 fixed to the mounting member 47 to the reducer 4, and increasing the efficiency with which the reducer 4 outputs reduced rotation.

The reducer 4 of this embodiment further includes a second member 42 that is rotatable relative to the first member 41. The first member 41 has internal teeth 412. The reduction section 45 includes a crankshaft 43 rotatably supported by the second member 42, 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 this structure, the reducer 4 of this embodiment can be stably protected from impacts.

The reducer 4 of this embodiment further includes an attachment member 47 arranged to leave a gap between the first member 41 in the radial direction DF perpendicular to the axis LB of the through hole 41b, and a bolt 7 that is passed through the bush 6 and fixes the accommodating portion 48 to the attachment member 47. The width w8 of the gap between the first member 41 and the attachment member 47 in the radial direction DF is greater than the width w9 of the gap between the bush 6 and the bolt 7 in the radial direction DF. This provides the following effects. When the attachment member 47 receives an impact and moves in the radial direction DF to transmit the impact to the first member 41, it is possible that a surface other than the attachment surface 47a of the attachment member 47 directly contacts the surface of the first member 41. For example, it is possible that the surface 41d of the first member 41 and the surface 47c of the attachment member 47, which face each other in the radial direction DF in FIG. 3, directly contact each other. Here, because the width w8 is greater than the width w9, when the mounting member 47 receives an impact and moves in the radial direction DF, the bolt 7 can come into contact with the buffer portion 5 in the radial direction DF before the surface of the mounting member 47 and the surface of the first member 41 come into direct contact in the radial direction DF. Therefore, the impact can be absorbed by the buffer portion 5 before the surface of the mounting member 47 and the surface of the first member 41 come into direct contact in the radial direction DF. This makes it possible to prevent a strong impact from being transmitted from the mounting member 47 to the first member 41 due to direct contact between the surface of the mounting member 47 and the surface of the first member 41 in the radial direction DF.

The reduction gear 4 of this embodiment described above can be used in the construction machine 1. In this case, it can be said that the construction machine 1 is equipped with the reduction gear 4. The construction machine 1 is, for example, a power shovel. When the construction machine 1 is a power shovel, the reduction gear 4 outputs rotation that drives, for example, the boom, arm, bucket, etc. of the power shovel. According to the construction machine 1 equipped with the reduction gear 4 of this embodiment, the construction machine 1 is driven by the rotation slowed down by the reduction gear 4, while the impact transmitted to the first member 41 of the reduction gear 4 can be mitigated.

Although the present embodiment has been described using specific examples, these specific examples do not limit the present embodiment. The above-described present embodiment can be implemented using various other specific examples, and various omissions, substitutions, modifications, and additions can be made without departing from the spirit of the present embodiment.

Below, 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, parts that can be configured similarly to the specific example described above will be designated by the same reference numerals as those used for the corresponding parts in the specific example described above, and duplicate descriptions will be omitted.

(Variation 1)
In the above embodiment, a case has been described in which the second portion 52, which is more easily deformed than the first portion 51 when subjected to a certain stress, is located more inward in the radial direction DF than the first portion 51 in the buffer portion 5. However, the configuration of the buffer portion 5 is not limited to this. Fig. 4 is an enlarged cross-sectional view showing an enlarged view of the vicinity of the buffer portion 5 in a cross section of the construction machine 1 of Modification 1. In particular, Fig. 4 shows a cross section of the construction machine 1 cut along a plane passing through the axis LB of the through hole 41b.

In the first modification, the second portion 52, which is more easily deformed than the first portion 51 when subjected to a certain stress, is located radially inward of the first portion 51 in the radial direction DF. In this case as well, the buffer portion 5 having the first portion 51 and the second portion 52 can increase the efficiency with which rotation is input to the reducer 4 while mitigating the impact transmitted from the bolt 7 to the first member 41, and can increase the efficiency with which the reducer 4 outputs reduced rotation.

In addition, in the first modification, the first portion 51, which is located radially inward of the second portion 52 in the radial direction DF, forms the first flange portion 53 and the second flange portion 54. Even in this case, the first flange portion 53 and the second flange portion 54 can prevent the buffer portion 5 from slipping out of the through hole 41b.

(Variation 2)
In the above-described embodiment and modified examples, an example has been described in which the mounting member 47 can be considered to be part of the reducer 4. However, the form of the mounting member 47 is not limited to this. Fig. 5 is a cross-sectional view showing an example of the configuration around the reducer 4 of a construction machine 1 incorporating a reducer 4 of modified example 2. In particular, Fig. 5 is a cross-sectional view of the construction machine 1 cut along a plane passing through the rotation axis LA of the rotation output by the reducer 4.

In Modification 2, the mounting member 47 is a particularly large member compared to the first member 41 of the reducer 4 and the reduction section 45, which form part of the construction machine 1. As an example, the mounting member 47 in Modification 2 is a member that is driven by the rotation output by the reduction section 45. As an example, if the construction machine 1 is a power shovel, the mounting member 47 in Modification 2 is a member that forms the boom, arm, bucket, etc. of the power shovel. In Modification 2, the electric motor 3 is fixed directly to the mounting member 47.

In other words, the construction machine 1 of the modified example 2 includes a first member 41 having a reduction unit 45 that reduces the input rotation, a storage unit 48 that stores the reduction unit 45, and a through hole 41b used to fix the storage unit 48 to the mounting member 47, a buffer unit 5 that has a cylindrical shape and covers the inner wall 41c of the through hole 41b, and has a first part 51 and a second part 52 that differ in their ease of deformation when subjected to a certain stress, and a bush 6 that has a cylindrical shape and is provided inside the buffer unit 5, a reduction gear 4, a mounting member 47 that is arranged so that a gap is created between the first member 41 and the mounting member 47 in the radial direction DF perpendicular to the axis LB of the through hole 41b, and a bolt 7 that is passed through the bush 6 and fixes the storage unit 48 to the mounting member 47. Also in the modified example 2, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is larger than the width w9 of the gap between the bush 6 and the bolt 7 in the radial direction DF.

In the construction machine 1 of the second modified example, as in the reducer 4 of the above-described embodiment, the width w8 is greater than the width w9, so that when the mounting member 47 receives an impact and moves in the radial direction DF, the bolt 7 can come into contact with the buffer portion 5 in the radial direction DF before the surface of the mounting member 47 and the surface of the first member 41 come into direct contact in the radial direction DF.

(Variation 3)
In the above-mentioned embodiment and each modified example, an example has been described in which the transmission gear 431 is fixed to one end of the crankshaft 43 on the first side SA1 in the rotation axis direction DA. However, the aspect of the reducer 4 is not limited to this. Fig. 6 is a cross-sectional view showing an example of the configuration of the electric motor 3 and the reducer 4 and its surroundings in a construction machine 1 incorporating a reducer 4 of modified example 3. In particular, Fig. 6 is a cross-sectional view of the construction machine 1 cut along a plane passing through the rotation axis LA of the rotation output by the reducer 4.

In the third modification, the transmission gear 431 is fixed to one end of the crankshaft 43 on the second side SA2 in the rotational axis direction DA. The transmission gear 431 is also disposed on the second side SA2 in the rotational axis direction DA of the first external gear 441 and the second external gear 442. The drive gear 461 provided on 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.

In the construction machine 1 of the third modified example, the buffer section 5 can also reduce the impact transmitted to the reducer 4, particularly the first member 41 and the reduction section 45 that are part of the reducer 4. In addition, torque can be appropriately transmitted from the electric motor 3 to the reducer 4. As a result, in the construction machine 1 of the third modified example, the rotation input from the electric motor 3 can be decelerated by the reducer 4 and then output.

(Variation 4)
In the above-described embodiment and each modified example, an example has been described in which the main body 32 of the electric motor 3 is fixed to the mounting member 47. However, the manner in which the electric motor 3 is fixed is not limited to this. Fig. 7 is a cross-sectional view showing an example of the configuration of the electric motor 3 and the surrounding area of the reduction gear 4 of a construction machine 1 incorporating a reduction gear 4 of modified example 4. In particular, Fig. 7 is a cross-sectional view of the construction machine 1 cut along a plane passing through the rotation axis LA of the rotation output by the reduction gear 4.

In the fourth modification, the main body 32 of the electric motor 3 is fixed to the second member 42. In FIG. 7, the construction machine 1 further includes a connecting member 8 that connects the electric motor 3 and the second member 42 of the reduction gear 4. The connecting member 8 is fixed to the surface of the first side SA1 of the second member 42 by a bolt 81. The main body 32 of the electric motor 3 is also fixed to the surface of the first side SA1 of the connecting member 8 by a bolt (not shown). As a result, the main body 32 of the electric motor 3 is positioned on the first side SA1 of the second member 42 and fixed to the second member 42.

The connecting member 8 has a through hole 82 that passes through the connecting member 8 in the rotation axis direction DA. The rotating shaft 31 of the electric motor 3 is inserted into the through hole 82. The base end of the input shaft 46 of the reducer 4 on the electric motor 3 side (first side SA1 in the rotation axis direction DA) is connected to the rotating shaft 31 of the electric motor 3 within the through hole 82.

In FIG. 7, the transmission gear 431 is fixed to one end of the crankshaft 43 on the second side SA2 in the rotational axis direction DA. The transmission gear 431 is also disposed on the second side SA2 in the rotational axis direction DA of the first external gear 441 and the second external gear 442. 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. As a result, the drive gear 461 provided at the tip portion 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.

7, the mounting member 47 to which the accommodating portion 48 is fixed is a member forming a part of the construction machine 1. A part of the mounting member 47 is located on the first side SA1 of the flange portion 49 in the rotational axis direction DA. As a result, the flange portion 49 faces a part of the mounting member 47. A screw hole 474 extending in the rotational axis direction DA and opening on the second side SA2 is provided in the part of the mounting member 47 facing the flange portion 49. The reducer 4 also has a fixing auxiliary member 9 arranged on the second side SA2 of the first member 41 of the reducer 4 in the rotational axis direction DA. The fixing auxiliary member 9 covers the entire 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 of the flange portion 49 in the rotational axis direction DA. As a result, the flange portion 49 faces a part of the fixing auxiliary member 9. A through hole 91 is provided in the portion of the fixing auxiliary member 9 facing the flange portion 49, extending in the direction of the rotation axis DA and penetrating the fixing auxiliary member 9.

In FIG. 7, the mounting member 47 and the fixing auxiliary member 9 are fixed to the housing portion 48 by the bolt 7. Specifically, as shown in FIG. 7, the mounting member 47 and the fixing auxiliary member 9 can be fixed to the housing portion 48 by tightening the bolt 7 inserted into the through hole 91 and the through hole 41b into the screw hole 474.

In the fourth modification, the reducer 4 also has a buffer section 5 that covers the inner wall 41c of the through hole 41b. The reducer 4 also has a bush 6 provided inside the buffer section 5. The bolt 7 is passed through the buffer section through hole 5a and the bush through hole 6a.

In variant 4, the dimension w1 of the bushing 6 is also greater than the dimension w2 of the through hole 41b. Also, in variant 4, the dimension w1 of the bushing 6 is also greater than the dimension w3 of the flange portion 49. This prevents the mounting member 47 and the first member 41 from coming into direct contact in the direction of the rotation axis DA. Also, it prevents the fixing auxiliary member 9 and the first member 41 from coming into direct contact in the direction of the rotation axis DA.

In the construction machine 1 of the fourth modified example, the buffer section 5 can also reduce the impact transmitted to the reducer 4, particularly the first member 41 and the reduction section 45 which are part of the reducer 4. Furthermore, when the rotation input from the electric motor 3 is slowed down by the reducer 4 and output, the torque from the electric motor 3 can be appropriately transmitted. As a result, in the construction machine 1 of the fourth modified example, the rotation input from the electric motor 3 can also be slowed down by the reducer 4 and output.

(Variation 5)
In the above-described embodiment and each modified example, an example has been described in which the through hole 41b used for fixing the accommodation portion 48 to the mounting member 47 is provided in the first member 41. However, the configuration of the reducer 4 and the construction machine 1 is not limited to this. Fig. 8 is a cross-sectional view showing an example of the configuration of the electric motor 3 and the reducer 4 and its surroundings in a construction machine 1 incorporating a reducer 4 of modified example 5. In particular, Fig. 8 is a cross-sectional view of the construction machine 1 cut along a plane passing through the rotation axis LA of the rotation output by the reducer 4.

In variant 5, the first member 41 does not have a through hole 41b. Instead, the mounting member 47 has a through hole 47d that is used to fix the storage portion 48 to the mounting member 47. In this case, the mounting member 47 may be a member that can be considered to be part of the reducer 4. The mounting member 47 may be a particularly large member compared to the first member 41 and reduction portion 45 of the reducer 4, which form part of the construction machine 1. In FIG. 8, the mounting member 47 is a member that can be considered to be part of the reducer 4.

The explanation given for the through hole 41b provided in the first member 41 in the above embodiment and variants 1 to 4 can also be applied to the through hole 47d provided in the mounting member 47 in variant 5, unless there is a contradiction.

The reducer 4 shown in FIG. 8 further includes a buffer section 5 having a cylindrical shape and covering the inner wall 47e of the through hole 47d. The buffer section 5 has a first portion 51 and a second portion 52 that differ in their tendency to deform when subjected to a certain stress. The reducer 4 further includes a bushing 6 having a cylindrical shape provided inside the buffer section 5. The explanations given for the buffer section 5, bushing 6, and bolt 7 in the above embodiment and variants 1 to 4 can also be applied to the buffer section 5, bushing 6, and bolt 7 in variant 5, unless contradictory.

In variant 5, a screw hole 491 that extends in the rotation axis direction DA and opens on the second side SA2 is provided in the portion of the flange portion 49 that faces the mounting member 47. In variant 5, the first member 41 (case 41a) is fixed to the mounting member 47 by passing a bolt 7 through the through hole 47d and screwing it into the screw hole 491 of the flange portion 49, and the housing portion 48 is fixed to the mounting member 47. The bolt 7 is passed through the buffer portion through hole 5a and through the bush through hole 6a.

The dashed line marked with the symbol LC in FIG. 8 is an imaginary line indicating the axis LC of the through hole 47d. The direction in which the through hole 47d extends (the direction in which the axis LC of the through hole 47d extends) is referred to as the axial direction DG. The direction perpendicular to the axis LC of the through hole 47d is referred to as the radial direction DH. In the fifth modified example, the dimension w10 of the bush 6 in the axial direction DG in which the through hole 47d extends is greater than the dimension w11 of the through hole 47d in the axial direction DG. This allows the bush 6 to be positioned so that it protrudes from the through hole 47d on both sides of the through hole 47d. This causes the mounting member 47 and the first member 41 to be separated in the axial direction DG. This makes it possible to suppress the direct transmission of impact from the mounting member 47 to the first member 41 in the axial direction DG.

Although not shown, the mounting member 47 of the fifth modified example may have a portion facing the first member 41 in the radial direction DH. In this case, the mounting member 47 is arranged so that a gap is provided between the mounting member 47 and the first member 41 in the radial direction DH perpendicular to the axis LC of the through hole 47d. In particular, the mounting member 47 is arranged so 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 bush 6 and the bolt 7 in the radial direction DH. This allows the shock absorbing section 5 to absorb the impact before the surface of the mounting member 47 and the surface of the first member 41 come into direct contact in the radial direction DH. Therefore, it is possible to prevent a strong impact from being transmitted from the mounting member 47 to the first member 41 due to direct contact between the surface of the mounting member 47 and the surface of the first member 41 in the radial direction DH.

In the construction machine 1 of the fifth modified example, the buffer section 5 can also reduce the impact transmitted to the reducer 4, particularly the first member 41 and the reduction section 45 that are part of the reducer 4. In addition, torque can be appropriately transmitted from the electric motor 3 to the reducer 4. As a result, in the construction machine 1 of the fifth modified example, the rotation input from the electric motor 3 can be decelerated by the reducer 4 and then output.

Among the embodiments disclosed in this specification, those that are composed of multiple objects may be integrated into one object, and conversely, those that are composed of one object may be separated into multiple objects. Regardless of whether they are integrated or not, it is sufficient that they are configured in such a way that the object of the invention can be achieved.

The aspects of the present invention are not limited to the individual embodiments described above, but include various modifications that may be conceived by a person skilled in the art, and the effects of the present invention are not limited to the above. In other words, various additions, modifications, and partial deletions are possible within the scope that does not deviate from the conceptual idea and intent of the present invention that is derived from the contents defined in the claims and their equivalents.

Reference Signs List 1 Construction machine 2 Driving machine 3 Electric motor 31 Rotating shaft 4 Speed reducer 41 First member 41b Through hole 42 Second member 43 Crankshaft 44 External gear 45 Speed reducer portion 47 Mounting member 48 Storage portion 49 Flange portion 5 Buffer portion 51 First portion 52 Second portion 6 Bush 7 Bolt

Claims (11)

1. A speed reducer that reduces the speed of the input rotation;
   a first member having an accommodation portion that accommodates the reduction gear portion and having a through hole that is used for fixing the accommodation portion to a mounting member;
   a buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion that differ in their ease of deformation when subjected to a certain stress.
2. The reducer of claim 1, further comprising a bushing having a cylindrical shape provided inside the buffer portion.
3. The reducer of claim 2, wherein the dimension of the bush in the axial direction in which the through hole extends is greater than the dimension of the through hole in the axial direction.
4. The first member further includes a flange portion that protrudes from the housing portion in a direction intersecting an axial direction in which the through hole extends and faces the mounting member,
   The through hole is provided in the flange portion,
   The reducer according to claim 2 , wherein a dimension of the bush in the axial direction is larger than a dimension of the flange portion in the axial direction.
5. a bolt that is passed through the bush and fixes the housing to the mounting member;
   The reducer according to claim 2 , wherein a dimension of the bush in a radial direction perpendicular to an axis of the through hole is equal to or greater than a dimension of a head of the bolt in the radial direction.
6. Further comprising a second member rotatable relative to the first member,
   The first member has internal teeth;
   2. The reducer according to claim 1, wherein the reduction section comprises a crankshaft rotatably supported by the second member, and an external gear having a through hole through which the crankshaft passes and having external teeth that mesh with internal teeth of the first member.
7. The mounting member is disposed so as to have a gap between the mounting member and the first member in a radial direction perpendicular to an axis of the through hole;
   a bolt that is passed through the bush and fixes the housing to the mounting member,
   The reducer according to claim 2 , wherein a width of a gap between the first member and the mounting member in the radial direction is larger than a width of a gap between the bush and the bolt in the radial direction.
8. A speed reducer that reduces the speed of the input rotation;
   A first member having a housing portion that houses the speed reducing portion;
   a mounting member to which the accommodation portion is fixed, the mounting member having a through hole used for fixing the accommodation portion to the mounting member;
   a buffer portion having a cylindrical shape, covering the inner wall of the through hole, and having a first portion and a second portion that differ in their ease of deformation when subjected to a certain stress.
9. A construction machine equipped with a reducer according to any one of claims 1 to 8.
10. a reduction gear comprising: a reduction section which reduces the speed of an input rotation; a first member having a housing section which houses the reduction section and which is provided with a through hole used for fixing the housing section to a mounting member; a buffer section which has a cylindrical shape, covers an inner wall of the through hole, and has a first part and a second part which differ in their ease of deformation when subjected to a certain stress; and a bush which is provided inside the buffer section and has a cylindrical shape;
    The mounting member is disposed between the first member and the mounting member such that a gap is provided between the mounting member and the first member in a radial direction perpendicular to an axis of the through hole;
    a bolt that is passed through the bush and fixes the housing portion to the mounting member,
    A construction machine, wherein the width of a gap between the first member and the mounting member in the radial direction is larger than the width of a gap between the bush and the bolt in the radial direction.
11. A reducer including a first member having a reduction section that reduces the speed of an input rotation and a housing section that houses the reduction section;
    a mounting member to which the accommodation portion is fixed, the mounting member having a through hole used for fixing the accommodation portion to the mounting member;
    a buffer portion having a cylindrical shape, covering an inner wall of the through hole, and having a first portion and a second portion that differ in ease of deformation when subjected to a certain stress;
    A bush provided inside the buffer portion and having a cylindrical shape;
    a bolt that is passed through the bush and secures the accommodating portion to the mounting member.