REDUCTION GEARBOX AND CONSTRUCTION MACHINERY

Abstract

[Task] A shock transmitted to a reduction gear 4 is damped. [Solution] A reduction gear 4 includes a reduction portion 45 that decelerates an input rotation, a first member 41 including a receiving portion 48 for receiving the reduction portion 45 and provided with a through hole 41b for fixing the receiving portion 48 to a mounting member 47, and a buffer portion 5 having a tubular shape and covering an inner wall 41c of the through hole 41b and including a first portion 51 and a second portion 52 that differ in deformability under a certain stress.

Description

Technical area

[0001] The present invention relates to a reduction gear and a construction machine. Background technology

[0002] A device that generates a driving force by rotating an electric motor is conventionally known. For example, Patent Document 1 describes an electric linear actuator for generating a driving force in a construction machine such as an excavator. Specifically, Patent Document 1 describes that the electric linear actuator is used to drive a boom, arm, bucket, or the like of the excavator.

[0003] Furthermore, a technique is known in which, in the device that generates a driving force by the rotation output of the electric motor, a shock acting on the device is dampened. For example, Patent Document 1 describes a shock-absorbing device formed by an elastic body such as a spring, which dampens an impact force acting on a piston of the electric linear actuator. Citation listPatent document

[0004] Patent Document 1: International Publication No. WO 2013 / 114451 Disclosure of the invention

[0005] In some cases, a reduction gear was installed in a device that generates driving force through the rotation output of an electric motor to slow down the rotation of the electric motor. In this case, a shock could be transmitted to the reduction gear. In particular, in the case where the device in which the reduction gear was installed was used to drive a construction equipment, such as driving a boom, arm, bucket, or the like of an excavator, a relatively strong shock could be transmitted to the reduction gear. It was also suspected that by transmitting the strong shock to a part of the reduction gear, such as a section that has the function of slowing down an input rotation, the part of the reduction gear was damaged.For this reason, it was necessary to dampen a shock transmitted to the reduction gear, in particular to a part of the reduction gear.

[0006] The present invention has been made in consideration of the above circumstances, and the object of the present invention is to dampen a shock transmitted to a reduction gear.

[0007] A first aspect of the present disclosure relates to a reduction gear comprising: a reduction section that slows down an input rotation; a first member comprising a receiving portion for receiving the reduction portion and provided with a through-hole for fixing the receiving portion to a mounting member; and a buffer portion having a tubular shape and covering an inner wall of the through-hole and comprising a first portion and a second portion which differ in deformability under a certain stress.

[0008] According to a second aspect of the present disclosure, the reduction gear according to the above-described first aspect may further comprise a bushing provided inside the buffer portion and having a tubular shape.

[0009] According to a third aspect of the present disclosure, in the reduction gear according to the second aspect described above, a dimension of the bushing in an axial direction in which the through-hole extends may be larger than a dimension of the through-hole in the axial direction.

[0010] According to a fourth aspect of the present disclosure, in the reduction gear according to the above-described second aspect or the above-described third aspect, the first member may further include a flange portion projecting from the receiving portion in the direction crossing the axial direction in which the through-hole extends and facing the mounting member, the flange section may be provided with the through hole, and the dimension of the bushing in the axial direction may be larger than a dimension of the flange portion in the axial direction.

[0011] According to a fifth aspect of the present disclosure, the reduction gear according to any of the second to fourth aspects described above may further comprise a bolt which is passed through the bushing and serves to fix the receiving portion to the mounting member, wherein a dimension of the bushing in a radial direction perpendicular to an axis of the through-hole may be greater than or equal to a dimension of a head portion of the bolt in the radial direction.

[0012] According to a sixth aspect of the present disclosure, the reduction gear according to any of the first to fifth aspects described above may further comprise a second member relatively rotatable relative to the first member, wherein the first element may have internal teeth, and wherein the reduction portion may include a crankshaft rotatably supported on the second member, and an external gear provided with a through-hole through which the crankshaft passes and having external teeth that mesh with the internal teeth of the first member.

[0013] According to a seventh aspect of the present disclosure, the reduction gear according to any of the second to fifth aspects described above may further comprise: the mounting member arranged such that a gap exists between the mounting member and the first member in the radial direction perpendicular to the axis of the through-hole; and the bolt which is guided through the bushing and serves to fasten the receiving section to the mounting element, wherein a width of the gap between the first member and the mounting member in the radial direction may be larger than a width of a gap between the bushing and the bolt in the radial direction.

[0014] An eighth aspect of the present disclosure may include: a reduction section that slows down an input rotation; a first member including a receiving portion for receiving the reducing portion; a mounting element to which the receiving portion is attached and which is provided with a through-hole for attaching the receiving portion to the mounting element; and a buffer portion having a tubular shape and covering an inner wall of the through-hole and comprising a first portion and a second portion which differ in deformability under a certain stress.

[0015] A ninth aspect of the present disclosure relates to a construction machine including the reduction gear according to any one of the first to eighth aspects described above.

[0016] A tenth aspect of the present disclosure relates to a construction machine comprising: a reduction gear comprising a reduction portion that decelerates an input rotation, a first member including a receiving portion for receiving the reduction portion and provided with a through-hole for fixing the receiving portion to a mounting member, a buffer portion having a tubular shape and covering an inner wall of the through-hole and including a first portion and a second portion that differ in deformability under a certain stress, and a bushing provided inside the buffer portion and having a tubular shape; the mounting member arranged such that a gap exists between the mounting member and the first member in a radial direction perpendicular to an axis of the through-hole; and a bolt which is guided through the bushing and serves to fasten the receiving section to the mounting element, wherein a width of the gap between the first member and the mounting member in the radial direction is larger than a width of a gap between the bushing and the bolt in the radial direction.

[0017] An eleventh aspect of the present disclosure may include: a reduction gear comprising a reduction portion that decelerates an input rotation and a first member comprising a receiving portion for receiving the reduction portion; a mounting member to which the receiving portion is attached and which is provided with a through-hole for attaching the receiving portion to the mounting member; a buffer portion having a tubular shape and covering an inner wall of the through-hole and including a first portion and a second portion differing in deformability under a certain stress; a bushing provided inside the buffer portion and having a tubular shape; and a bolt which is passed through the bushing and serves to fasten the receiving section to the mounting element.

[0018] According to the present invention, a shock transmitted to a reduction gear can be damped while enabling required torque transmission. Brief explanation of the figures [ Fig. 1] Fig. 1 shows a cross-sectional view of a construction machine according to an embodiment. [ Fig. 2] Fig. 2 shows a cross-sectional view of a reduction gear according to the embodiment. [ Fig. 3] Fig. Figure 3 is an enlarged cross-sectional view showing an area shown in Fig. 1 is surrounded by a dot-dash line marked with a symbol III, enlarged. [ Fig. 4] Fig. 4 shows an enlarged cross-sectional view of the construction machine according to a modification 1. [ Fig. 5] Fig. 5 shows a cross-sectional view of the construction machine according to a modification 2. [ Fig. 6] Fig. 6 shows a cross-sectional view of the construction machine according to a modification 3. [ Fig. 7] Fig. 7 shows a cross-sectional view of the construction machine according to a modification 4. [ Fig. 8] Fig. 8 shows a cross-sectional view of the construction machine according to a modification 5. Forms for carrying out the invention

[0019] The present embodiment will be described in more detail with reference to drawings. First, a construction machine 1 in which a reduction gear 4 according to the present embodiment is installed will be described. Fig. 1 shows a cross-sectional view of a configuration example of the construction machine 1 in which the reduction gear 4 is installed, in an area around the reduction gear 4. Fig. 1 shows in particular a cross-sectional view of the construction machine 1 in which the reduction gear 4 is installed, cut in a plane passing through a rotation axis LA of a rotation output from the reduction gear 4. Fig. Figure 2 shows a cross-sectional view of the reduction gear 4, cut along the line II-II in Fig. 1.

[0020] A direction in which the rotation axis LA of a rotation output from the reduction gear 4 extends is referred to as the rotation axis direction DA. A side of the rotation axis direction DA on which a substrate portion 422 of a second element 42 (described below) is located, with an end plate portion 421 of the second element 42 (described below) of the reduction gear 4 serving as a reference, is referred to as the first side SA1. A side of the rotation axis direction DA opposite the side on which the substrate portion 422 of the second element 42 is located, with the end plate portion 421 of the second element 42 serving as a reference, is referred to as the second side SA2. Fig. 1, a mounting element 47 is located on the second side SA2 of the rotation axis direction DA of the reduction gear 4. A direction that revolves around the rotation axis LA is referred to as the circumferential direction DB of the rotation axis, and a direction perpendicular to the rotation axis LA is referred to as the radial direction DC of the rotation axis. The radial direction DC of the rotation axis is a direction in which a perpendicular line runs that can be drawn to the rotation axis LA.

[0021] The construction machine 1 includes the reduction gear 4 of the present embodiment. The construction machine 1 further includes an electric motor 3. The reduction gear 4 decelerates rotation input from the electric motor 3.

[0022] In the present embodiment, the electric motor 3 is a general electric motor. The electric motor 3 includes a body portion 32 and a rotating shaft 31 that rotates relative to the body portion 32. Fig. 1, the body portion 32 of the electric motor 3 is attached to the mounting element 47 described below. Although not shown, the electric motor 3 is attached to the mounting element 47 by means of a bolt and thus secured to the surface of the mounting element 47 located on the second side SA2. The mounting element 47 is, as shown in Fig. 1, is provided with a through-hole 471 that passes through the mounting member 47 in the rotational axis direction DA. The rotary shaft 31 of the electric motor 3 is inserted into the through-hole 471. The rotary shaft 31 projects toward the first side SA1 and extends in the rotational axis direction DA. Fig. 1, the axis of rotation about which the rotary shaft 31 rotates coincides with the axis of rotation LA of a rotation output by the reduction gear 4.

[0023] The reduction gear 4 will be described. The reduction gear 4 is arranged on the first side SA1 of the rotation axis direction DA of the electric motor 3. The reduction gear 4 includes a reduction portion 45, a first member 41, and a buffer portion 5. The reduction portion 45 decelerates input rotation. The first member 41 includes a receiving portion 48 for receiving the reduction portion 45, and the first member 41 is further provided with a through-hole 41b for fixing the receiving portion 48 to the mounting member 47 described below. The buffer portion 5 has a tubular shape and covers an inner wall 41c of the through-hole 41b. As described below, the buffer portion 5 includes a first portion 51 and a second portion 52, which differ in their deformability under a certain stress.The reduction gear 4 of the present embodiment further includes a bushing 6 described below, a bolt 7, the second member 42 and the mounting member 47. It should be noted that in . Fig. 1, an illustration of the shape of the first section 51 and the second section 52 is omitted and only the outer shape of the buffer section 5 is shown. Furthermore, in Fig. 2, an illustration of the buffer section 5, the bushing 6 and the bolt 7 is omitted.

[0024] In addition to the reduction section 45, the first element 41, and the buffer section 5, the reduction gear 4 includes the second element 42, which is relatively rotatable relative to the first element 41. The reduction section 45 decelerates an input from the electric motor 3 to rotate the first element 41 and the second element 42 relative to each other.

[0025] In the present embodiment, the first member 41 has internal teeth 412. The reduction section 45 includes crankshafts 43 rotatably supported on the second member 42, and external gears 44 provided with through-holes 44d through which the respective crankshafts 43 pass, and having external teeth 441a and 442a. In the reduction section 45, the crankshafts 43, to which rotation is input, cause eccentric vibration of the external gears 44. The external teeth 441a and 442a of the external gears 44 mesh with the internal teeth 412 of the first member 41. When the external teeth 441a and 442a of the external gears 44, which are subjected to eccentric vibration, mesh with the internal teeth 412 of the first member 41, the first member 41 and the second member 42 rotate relative to each other.

[0026] In the present embodiment, the external gear 44 is provided with the through holes 44d through which the respective crankshafts 43 pass.

[0027] In the present embodiment, the reduction section 45 includes the 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 the plurality of through-holes 44d, and the plurality of crankshafts 43 extend through the respective through-holes 44d.

[0028] In the present embodiment, the reduction gear 4 includes a cylindrical housing 41a as the first member 41. As the second member 42, the reduction gear 4 further includes a carrier 42a disposed inside the radial direction DC of the rotation axis of the housing 41a (on the side approaching the rotation axis LA in the radial direction DC of the rotation axis). The reduction gear 4 further includes an input shaft 46 that provides a driving force for rotating the carrier 42a. The mounting member 47 of the reduction gear 4 is provided with the through hole 471 for fixing the electric motor 3. The mounting member 47 has a cylindrical shape.

[0029] The first member 41 (the housing 41a) includes the receiving portion 48 for receiving the reduction portion 45, namely the crankshafts 43 and the external gears 44. In the present embodiment, the receiving portion 48 forms a part of the housing 41a, which has a cylindrical shape. The first member 41 (the housing 41a) is further provided with the through-hole 41b for fixing the receiving portion 48 to the mounting member 47. The through-hole 41b extends in the rotation axis direction DA. When the bolt 7 described below is passed through the through-hole 41b and screwed to 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.When the housing 41a is fixed to the mounting member 47 and the electric motor 3 is fixed to the mounting member 47, the electric motor 3 is fixed to the housing 41a via the mounting member 47.

[0030] The internal teeth 412 are arranged on the inner peripheral surface of the housing 41a. The internal teeth 412 are pin-shaped (round column-shaped) teeth arranged on the inner peripheral surface of the housing 41a. Specifically, the first member 41 includes internal tooth pins 412a as the internal teeth 412, which are inserted into pin grooves 412b. A plurality of the internal teeth 412 are arranged at equal intervals in the circumferential direction DB of the rotation axis.

[0031] The carrier 42a is rotatably mounted on the housing 41a by paired main bearings 42j, which are spaced apart in the rotation axis direction DA. The main bearings 42j are, for example, angular contact ball bearings. The carrier 42a is arranged coaxially with the housing 41a and the rotation axis LA.

[0032] The carrier 42a comprises the disc-shaped end plate portion 421 arranged on the second side SA2 of the rotation axis direction DA, the disc-shaped substrate portion 422 arranged on the first side SA1 of the rotation axis direction DA, and three column portions 423 formed integrally with the substrate portion 422 and projecting from the substrate portion 422 toward the end plate portion 421. The Fig. The column sections 423 shown in Figure 2 each have a columnar shape, with its cross section perpendicular to the rotation axis direction DA having a substantially triangular shape with rounded corners. The column sections 423 are arranged at equal intervals in the circumferential direction DB of the rotation axis. The column sections 423 and the end plate section 421 are screwed together by means of a bolt 42b in a state in which the front end surfaces of the column sections 423 overlap with the end plate section 421, and are thereby fixed to each other. In this state, a space having a predetermined width in the rotation axis direction DA is formed between the substrate section 422 and the end plate section 421.

[0033] A bolt screw hole 42c is formed in the column portion 423, into which the bolt 42b is screwed. A bolt insertion hole 42d is formed in the end plate portion 421, into which the bolt 42b is inserted. The bolt 42b, inserted into the bolt insertion hole 42d from the side opposite the column portion 423 with the end plate portion 421 therebetween, is screwed into the bolt screw hole 42c of the column portion 423. A pin 42e for positioning the end plate portion 421 relative to the substrate portion 422 is arranged further inward than the bolt 42b in the radial direction DC of the rotation axis. The pin 42e is arranged to straddle the column portion 423 and the end plate portion 421. It should be noted that the column sections 423 do not necessarily have to be formed integrally with the substrate section 422.In this case, the column sections 423 are screwed to the substrate section 422. Furthermore, the column sections 423 do not necessarily have to have a columnar shape; their cross-section perpendicular to the rotation axis direction DA may have a substantially triangular shape with rounded corners. It is sufficient if a space having a predetermined width in the rotation axis direction DA is formed between the substrate section 422 and the end plate section 421 by the column sections 423. Alternatively, the column sections 423 may be round-columnar.

[0034] A plurality of hole portions 42f and 42g (e.g., three each in the present embodiment) are formed in the end plate portion 421 and the substrate portion 422, respectively, into which the crankshafts 43 of the reduction portion 45 are inserted. The hole portions 42f and 42g are arranged at equal intervals in the circumferential direction DB of the rotation axis. Further, at the center of the end plate portion 421 and the substrate portion 422 in the radial direction DC of the rotation axis, a through hole 42h and a through hole 42i are formed, respectively, which pass through in the rotation axis direction DA. The input shaft 46 is inserted into the through holes 42h and 42i. The input shaft 46 is arranged coaxially with the housing 41a and the rotation axis LA.

[0035] A proximal end portion of the input shaft 46 on the electric motor 3 side (on the second side SA2 of the rotation axis direction DA) is coupled to the rotating shaft 31 of the electric motor 3. As a result, the input shaft 46 rotates together with the rotating shaft 31. A front end portion 46a of the input shaft 46 on the side opposite the electric motor 3 (on the first side SA1 of 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 provided integrally with the front end portion 46a of the input shaft 46.

[0036] The reduction section 45 rotates the carrier 42a at a speed reduced by a predetermined ratio from the speed of the input shaft 46. The reduction section 45 includes a plurality of (e.g., three in the present embodiment) transmission gears 431 meshing with the drive gear 461, and the plurality of (e.g., three in the present embodiment) crankshafts 43, one ends of which are fixed to the respective transmission gears 431. The transmission gears 431 are fixed to one ends of the crankshafts 43 on the first side SA1 of the rotation axis direction DA. In the present embodiment, the reduction section 45 further includes a first external gear 441 and a second external gear 442, which rotate oscillatingly with the rotation of the crankshafts 43, as external gears 44.

[0037] The transmission gears 431 are fixed to one end of the crankshafts 43; therefore, rotation of the rotary shaft 31 is transmitted to the crankshafts 43 via the transmission gears 431. The crankshafts 43 are arranged parallel to the input shaft 46. That is, the crankshafts 43 rotate about the rotation axis parallel to the rotation axis LA of a rotation output from the reduction gear 4. The crankshaft 43 is rotatably supported on the end plate portion 421 via a first crank bearing 43a. The crankshaft 43 is further rotatably supported on the substrate portion 422 via a second crank bearing 43b. The first crank bearing 43a and the second crank bearing 43b are, for example, tapered roller bearings.

[0038] At the center of the crankshaft 43 in the rotational axis direction DA, a first eccentric portion 43c and a second eccentric portion 43d are formed, which are eccentric to the shaft center of the crankshaft 43. The first eccentric portion 43c and the second eccentric portion 43d are arranged adjacent to each other between the first crank bearing 43a and the second crank bearing 43b in the rotational axis direction DA. 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 phase angle of the first eccentric portion 43c and that of the second eccentric portion 43d differ from each other.

[0039] These crankshafts 43 are inserted into the respective hole portions 42f and the respective hole portions 42g of the end plate portion 421 and the substrate portion 422, respectively. That is, the crankshafts 43, like the hole portions 42f and the hole portions 42g, are arranged at equal intervals in the circumferential direction DB of the rotation axis.

[0040] 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. Via the roller bearings 43e and 43f, the first external gear 441 and the second external gear 442 oscillate with the rotation of the crankshafts 43.

[0041] The first external gear 441 and the second external gear 442 are arranged in a space between the substrate 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 and 442a, respectively, which mesh with the internal teeth 412 of the housing 41a. Formed in the first external gear 441 and the second external gear 442 are a first through-hole 44a arranged around the rotation axis LA, second through-holes 44b into which the respective column portions 423 are inserted, and through-holes 44d into which the respective crankshafts 43 are inserted. The eccentric portions 43c and 43d of the crankshaft 43 are inserted into the through-hole 44d. The input shaft 46 is inserted into the first through hole 44a.

[0042] 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, the first eccentric portion 43c and the second eccentric portion 43d swingably rotate due to rotation of the crankshafts 43, and thus the first external gear 441 and the second external gear 442 swingably rotate while meshing with the internal teeth 412 of the housing 41a.

[0043] The action of the reduction gear 4 is described. When the electric motor 3 is driven, the input shaft 46 is driven together with the rotating shaft 31. The rotation of the input shaft 46 then causes the transmission gears 431 to rotate via the drive gear 461. As a result, the crankshafts 43 rotate together with the transmission gears 431.

[0044] When the crankshaft 43 rotates, the first external gear 441 rotates with the momentum of the first eccentric portion 43c while meshing with the internal teeth 412. Further, the second external gear 442 rotates with the momentum of the second eccentric portion 43d while meshing with the internal teeth 412. That is, the crankshafts 43 rotate around the rotation axis parallel to the rotation axis LA of a rotation output from the reduction gear 4 and orbit the rotation axis LA. The rotation of the crankshafts 43 thus drives the first external gear 441 and the second external gear 442.

[0045] When the first external gear 441 and the second external gear 442 are driven, the second member 42 (the carrier 42a), in which the column portions 423 are 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 relative to the housing 41a, which is fixed to the electric motor 3 via the mounting member 47, at a speed reduced from the speed of the input shaft 46. Consequently, rotation of the electric motor 3 can be slowed down by the reduction gear 4.

[0046] It should be noted that, as the reduction gear 4, the reduction gear 4 in which the reduction section 45 includes the crankshafts 43 and the external gears 44 has been described in particular; however, the shape of the reduction gear 4 is not limited to this. It is also possible that the reduction section 45 of the reduction gear 4 includes a planetary gear rotatably supported on the second member 42, and the planetary gear, to which rotation is input, meshes with the internal teeth 412 of the first member 41 to rotate the first member 41 and the second member 42 relative to each other. That is, the reduction gear 4 may alternatively be a planetary gear reduction gear.

[0047] Details of the through-hole 41b, as well as the buffer portion 5 and the bushing 6, will be described. In the present embodiment, the first member 41 is provided with a plurality of through-holes 41b. Fig. Figure 3 is an enlarged cross-sectional view showing an area shown in Fig. 1 is surrounded by a two-dot dashed line marked with a symbol III. In the case of a Fig. 1 is an imaginary line representing an 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 round-columnar shape, the axis LB is a straight line passing through the center of the circle of the cross section of the through-hole 41b. A direction in which the through-hole 41b extends (a direction in which the axis LB of the through-hole 41b extends) is also referred to as an 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 a rotation output from the reduction gear 4 extends.A side of the axial direction DD on which the mounting member 47 is located, with the through-hole 41b serving as a reference, is referred to as the first side SD1. A side of the axial direction DD opposite to the side on which the mounting member 47 is located, with the through-hole 41b serving as a reference, is referred to as the second side SD2. A direction that revolves around the axis LB of the through-hole 41b is referred to as the circumferential direction DE. A direction perpendicular to the axis LB of the through-hole 41b is referred to as the radial direction DF. The radial direction DF is a direction in which a perpendicular line that can be drawn to the axis LB runs.

[0048] In the present embodiment, a plurality of through holes 41b are provided so as to be arranged side by side in the circumferential direction DB of the rotation axis revolving around the rotation axis LA. The through holes 41b surround the receiving portion 48 from the outside in the radial direction DC of the rotation axis perpendicular to the rotation axis LA. The number of through holes 41b can be appropriately changed according to the magnitude of a torque required to be transmitted when transmitting the torque from the electric motor 3 to the reduction gear 4. In this case, the buffer portion 5 described below is provided at each of the through holes 41b.

[0049] In the present embodiment, the first member 41 further includes a flange portion 49 that protrudes from the receiving portion 48 in the direction crossing the axial direction DD in which the through-hole 41b extends, and opposes the mounting member 47. In the present embodiment, the flange portion 49 protrudes outward from the receiving portion 48 in the radial direction DC of the rotation axis. The flange portion 49 further extends in the circumferential direction DB of the rotation axis. Thus, the flange portion 49 surrounds the receiving portion 48 from the outside in the radial direction DC of the rotation axis. The flange portion 49 is provided with the through-hole 41b. In the present embodiment, the mounting member 47 has a mounting surface 47a provided with a screw hole 47b. The flange portion 49 has a surface opposite the mounting surface 47a.A surface of the flange portion 49 opposite the mounting surface 47a (a surface on the first side SD1 of the axial direction DD) is referred to as a first surface 49a. A surface of the flange portion 49 opposite the first surface 49a side in the axial direction DD (a surface on the second side SD2 of the axial direction DD) is referred to as a 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. A plurality of through holes 41b are provided so as to be opened on the first surface 49a and the second surface 49b of the flange portion 49.

[0050] The reduction gear 4 includes the buffer portion 5, which has a tubular shape and covers the inner wall 41c of the through-hole 41b. The buffer portion 5 is a portion that, when the mounting member 47 is subjected to an impact, absorbs 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. The buffer portion 5 has a tubular shape and thus has a buffer portion through-hole 5a extending in the axial direction DD. The bolt 7 described below is passed through the buffer portion through-hole 5a. In the present embodiment, the buffer portion 5 abuts the inner wall 41c of the through-hole 41b continuously 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 adhered to the inner wall 41c of the through-hole 41b by, for example, an adhesive, and is thus fixed to the inner wall 41c of the through-hole 41b.

[0051] The buffer portion 5 includes the first portion 51 and the second portion 52, which differ in their deformability under a certain stress. The first portion 51 and the second portion 52 each have a tubular 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 arranged further inward in the radial direction DF than the first portion 51 (on the side approaching the axis LB in the radial direction DF). The first portion 51 abuts continuously in the circumferential direction DE against the inner wall 41c of the through-hole 41b. The second portion 52 abuts continuously in the circumferential direction DE against an inner wall 51a of the first portion 51.The second section 52 adheres, for example, by means of an adhesive to the inner wall 51a of the first section 51 and is thus attached to the inner wall 51a of the first section 51.

[0052] In the present embodiment, the second portion 52 is more easily deformable under a certain stress than the first portion 51. Here, the elongation amount of the first portion 51 and that of the second portion 52 when, for example, the first portion 51 and the second portion 52 are subjected to a certain tensile stress can be used as an indicator of deformability under a certain stress. That is, if the elongation amount of the first portion 51 and that of the second portion 52 are measured when they are subjected to a certain tensile stress, and the elongation amount of the second portion 52 is greater than that of the first portion 51, it can be assumed that the second portion 52 is more easily deformable under a certain stress than the first portion 51.The elongation amounts of the first section 51 and the second section 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 prepared for the first section 51 and the second section 52, and a tensile testing machine is prepared. Using the tensile testing machine, the test pieces are pulled so that a certain tensile stress is applied to the test pieces. The elongation amounts of the test pieces during the pulling process are then measured. The measured elongation amounts of the test pieces for the first section 51 and the second section 52 are then compared.

[0053] Furthermore, the shrinkage amount of the first portion 51 and the second portion 52 when the first portion 51 and the second portion 52 are subjected to a certain compressive stress can be used as an indicator of deformability under a certain stress. That is, if the shrinkage amount of the first portion 51 and the second portion 52 are measured when they are subjected to a certain compressive stress, and the shrinkage amount of the second portion 52 is greater than that of the first portion 51, it can be assumed that the second portion 52 is more easily deformable than the first portion 51 under a certain stress.The shrinkage amounts of the first section 51 and the second section 52 when subjected to a certain compression stress can be compared, for example, by the following method. According to JIS K6254:2016, test specimens having the same shape are prepared for the first section 51 and the second section 52, and a compression testing machine is prepared. Using the compression testing machine, the test specimens are then drawn so that a certain compression stress is applied to the test specimens. The shrinkage amounts of the test specimens during the drawing process are then measured. The measured shrinkage amounts of the test specimens for the first section 51 and the second section 52 are then compared.

[0054] In the present embodiment, the buffer portion 5 includes a first flange portion 53 overlapping the first surface 49a of the flange portion 49, and a second flange portion 54 overlapping the second surface 49b of the flange portion 49. The buffer portion 5 includes a cylindrical buffer portion body portion 55, the first flange portion 53, and the second flange portion 54. The first flange portion 53 is connected to an end portion of the buffer portion body portion 55 located on the first side SD1 of the axial direction DD. The second flange portion 54 is connected to an end portion of the buffer portion body portion 55 located on the second side SD2 of the axial direction DD. The first flange portion 53 and the second flange portion 54 each project outward from the buffer portion body portion 55 in the radial direction DF.The first flange portion 53 is in contact with the first surface 49a of the flange portion 49. The second flange portion 54 is in contact with the second surface 49b of the flange portion 49.

[0055] In the present embodiment, the first portion 51, which is located further outward in the radial direction DF than the second portion 52 (on the side away from the axis LB in the radial direction DF) and is less deformable than the second portion 52 under a certain stress, forms the first flange portion 53 and the second flange portion 54.

[0056] In the present embodiment, the first portion 51 and the second portion 52 are more easily deformed under a certain stress than the mounting member 47, the first member 41, the bolt 7, and the bushing 6 described below. The deformability of the first portion 51 and the second portion 52 under a certain stress can be ensured by selecting the material of the first portion 51 and the second portion 52, or can be ensured by increasing the proportion of the voids included 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 the shock transmitted from the mounting member 47 to the first member 41 can be absorbed. The material of the first portion 51 and the second portion 52 can be resin or metal.The material of the first section 51 and the second section 52 is, for example, rubber.

[0057] The buffer portion 5 includes the first flange portion 53 and the second flange portion 54, whereby the buffer portion 5 can be prevented from coming out of the through hole 41b.

[0058] The reduction gear 4 further includes the bushing 6, which is provided inside the buffer portion 5 and has a tubular shape. In the present embodiment, the bushing 6 has a cylindrical shape. The bushing 6 has a tubular shape and thus has a bushing through-hole 6a extending in the axial direction DD. The bolt 7 described below is passed through the bushing through-hole 6a. In the present embodiment, the bushing 6 abuts an inner wall 5b of the buffer portion through-hole 5a continuously in the circumferential direction DE. The bushing 6 is fixed to the inner wall 5b of the buffer portion through-hole 5a. The bushing 6 is adhered to the inner wall 5b of the buffer portion through-hole 5a, for example, by means of an adhesive, and is thus fixed to the inner wall 5b of the buffer portion through-hole 5a.An end portion of the bushing 6 located on the first side SD1 of the axial direction DD is referred to as the first end portion 6b. An end portion of the bushing 6 located on the second side SD2 of the axial direction DD is referred to as the second end portion 6c.

[0059] The material of the bushing 6 is selected to enable attachment to the mounting element 47 by means of the bolt 7. In the present embodiment, the material of the bushing 6 is metal. The material of the bushing 6 is, for example, iron.

[0060] In the present embodiment, a dimension w1 of the bushing 6 in the axial direction DD in which the through-hole 41b extends is larger than a dimension w2 of the through-hole 41b in the axial direction DD. Therefore, the bushing 6 can be arranged to protrude from the through-hole 41b on both sides of the through-hole 41b.

[0061] Furthermore, in the present embodiment, the dimension w1 of the bushing 6 in the axial direction DD is larger than a dimension w3 of the flange portion 49 in the axial direction DD. Therefore, the first end portion 6b of the bushing 6 can be arranged further on the first side SD1 of 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 further on the second side SD2 of the axial direction DD than the second surface 49b of the flange portion 49.

[0062] In the present embodiment, the reduction gear 4 further includes the bolt 7, which passes through the bushing 6 and serves to fasten the receiving portion 48 to the mounting member 47. In the present embodiment, the bolt 7 includes a shaft portion 7a provided with an external thread 7b, and a head portion 7c provided in one of the end portions of the shaft portion 7a. A dimension w4 of the bushing through-hole 6a in the radial direction DF perpendicular to the axis LB of the through-hole 41b is greater than or equal to a dimension w5 of the shaft portion 7a in the radial direction DF. Furthermore, the dimension w4 of the bushing through-hole 6a in the radial direction DF is smaller than a dimension w6 of the head portion 7c in the radial direction DF.Therefore, when the shaft portion 7a is passed through the bushing through-hole 6a and an end portion of the shaft portion 7a on the side opposite the side where the head portion 7c is provided is screwed to the screw hole 47b of the mounting member 47, the bushing 6 can be clamped between the head portion 7c and the mounting member 47. When the bushing 6 is clamped between the head portion 7c and the mounting member 47, the bushing 6 is fixed to the mounting member 47. In the present embodiment, the bushing 6 is further 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, when the bushing 6 is fixed to the mounting member 47 by means of the bolt 7, the first member 41 including the receiving portion 48 is fixed to the mounting member 47 via the bushing 6 and the buffer portion 5.

[0063] Further, a dimension 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 dimension w6 of the head portion 7c of the bolt 7 in the radial direction DF.

[0064] In the present embodiment, the reduction gear 4 further includes the mounting member 47, which is arranged such that a gap exists between the mounting member 47 and the first member 41 in the radial direction DF perpendicular to the axis LB of the through hole 41b. That is, in the present embodiment, the mounting member 47 forms a part of the reduction gear 4. As described above, the mounting member 47 of the present embodiment is a member to which the electric motor 3 is attached.

[0065] The first element 41 and the mounting element 47 may have surfaces that are opposite to each other in the radial direction DF. Fig. 3, a surface 41d of the first member 41 and a surface 47c of the mounting member 47 oppose each other in the radial direction DF. In the present embodiment, a width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is larger than a width w9 of a gap between the bushing 6 and the bolt 7 in the radial direction DF.

[0066] Here, the width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF corresponds to a 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 the surface perpendicular to the axis LB of the through-hole 41b. Furthermore, the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF corresponds to the gap between the bushing 6 and the bolt 7 in the radial direction DF when the bolt 7 is arranged at the through-hole 41b such that the axis of the bolt 7 coincides with the axis LB of the through-hole 41b.

[0067] As described above, the reduction gear 4 of the present embodiment includes the reduction portion 45 that decelerates input rotation, the first member 41 that includes the receiving portion 48 for receiving the reduction portion 45 and is provided with the through-hole 41b for fixing the receiving portion 48 to the mounting member 47, and the buffer portion 5 that has a tubular shape and covers the inner wall 41c of the through-hole 41b and includes the first portion 51 and the second portion 52 that differ in deformability under a certain stress. The number of through-holes 41b is set so that a torque of the magnitude required to transmit torque can be transmitted when transmitting torque from the electric motor 3 to the reduction gear 4, and thus the buffer portion 5 is provided at each of the through-holes 41b.The following effects can be achieved with the reduction gear 4. It is conceivable that the mounting member 47 is subjected to an impact. For example, when the reduction gear 4 is installed in the construction machine 1, such as an excavator, it is conceivable that the impact acting on the construction machine 1 from the outside is transmitted to the mounting member 47, thereby subjecting the mounting member 47 to the impact. At this time, it is conceivable that the impact acting on the mounting member 47 is also transmitted to the bolt 7, which is passed through the through-hole 41b and screwed to the screw hole 47b of the mounting member 47. In this case, it is conceivable that the bolt 7 moves in the radial direction DF due to the applied impact to transmit the impact to the first member 41.When the reduction gear 4 further includes the bushing 6, it is conceivable that due to the impact acting on the pin 7, the pin 7 and the bushing 6 move in the radial direction DF, and the impact acting on the pin 7 is transmitted to the first member 41 via the bushing 6. Here, the reduction gear 4 of the present embodiment includes the buffer portion 5, which has a tubular shape and covers the inner wall 41c of the through-hole 41b. The buffer portion 5 is arranged between the pin 7 and the first member 41 in the radial direction DF. Therefore, when the pin 7 moves in the radial direction DF and is to transmit the impact to the first member 41, the shock transmitted from the pin 7 to the first member 41 can be cushioned by the buffer portion 5.As a result, the shock transmitted from the bolt 7 via the first element 41 to the reduction section 45 can be dampened by the buffer section 5. Consequently, the shock transmitted to the reduction gear 4, in particular to the first element 41 and the reduction section 45, which form part of the reduction gear 4, can be dampened by the buffer section 5.

[0068] In the present embodiment, the buffer portion 5 includes the first portion 51 and the second portion 52, which differ in their deformability under a certain stress. In the present embodiment, the second portion 52 is more easily deformable under a certain stress than the first portion 51. The first portion 51 and the second portion 52 each have a tubular shape. By the buffer portion 5 including the first portion 51 and the second portion 52, the following effects can be achieved. When the bolt 7 moves in the radial direction DF and is to transmit a shock to the first member 41, the shock can be effectively dampened by the second portion 52, which is more easily deformable. It is also conceivable that, since the shock transmitted by the bolt 7 is particularly large, the second portion 52 deforms so much that no further deformation is possible.Also in this case, the impact can be dampened by the first section 51, which is less deformable than the second section 52.

[0069] By having the buffer portion 5 comprise the first portion 51 and the second portion 52, the following effects can also be achieved. The buffer portion 5 is less deformable than when the buffer portion 5 is formed only by the second portion 52, which is more easily deformable than the first portion 51. Therefore, when rotation is input to the reduction gear 4, the power of the input rotation can be prevented from leaking due to the buffer portion 5. In particular, when rotation is input to the reduction gear 4 from the electric motor 3 fixed to the mounting member 47, as in the present embodiment, the power of the rotation input from the electric motor 3 can be prevented from leaking due to the buffer portion 5.Specifically, the first portion 51, which is less deformable than the second portion 52, may be set so that deformation is less likely to occur with the force usually applied when rotation is input to the reduction gear 4. In this case, the deformation of the first portion 51 is reduced even if the deformation of the second portion 52 occurs when rotation is input to the reduction gear 4. When the deformation of the first portion 51 is reduced when rotation is input to the reduction gear 4, the amount of rotational force leaked due to the buffer portion 5 can be small, so that torque from the electric motor 3 can be properly transmitted to the reduction gear 4. Consequently, rotation can be efficiently input to the reduction gear 4 while the buffer portion 5 is provided.

[0070] According to the buffer portion 5 of the present embodiment, as described above, the second portion 52 may be set as a portion that, when the bolt 7 moves in the radial direction DF and is to transmit a shock to the first member 41, deforms more than the first portion 51 and significantly absorbs the shock. Moreover, the first portion 51 may be set as a portion that, when the bolt 7 moves in the radial direction DF and the shock to be transmitted to the first member 41 is particularly large and the second portion 52 has been completely deformed, further absorbs the shock. Alternatively, the first portion 51 may be set so that deformation is less likely to occur with the force usually applied when rotation is input to the reduction gear 4.Thereby, the efficiency with which rotation is input to the reduction gear 4 can be increased, while the buffer portion 5 is provided in the reduction gear 4 and the shock transmitted from the bolt 7 to the first member 41 in the radial direction DF is damped, so that the efficiency with which the reduction gear 4 outputs decelerated rotation can be increased.

[0071] The reduction gear 4 of the present embodiment further includes the bushing 6 provided inside the buffer portion 5 and having a tubular shape. Therefore, when the bushing 6 is fixed to the buffer portion 5, the buffer portion 5 is fixed to the first member 41, and the bushing 6 is fixed to the mounting member 47 by the bolt 7, the first member 41 including the receiving portion 48 can be stably fixed to the mounting member 47 via the bushing 6 and the buffer portion 5.

[0072] Furthermore, 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. This allows the bushing 6 to be arranged so as to protrude from the through-hole 41b on both sides of the through-hole 41b. Furthermore, 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. This allows the first end portion 6b of the bushing 6 to be arranged further on the first side SD1 of the axial direction DD than the first surface 49a of the flange portion 49, and the second end portion 6c of the bushing 6 to be arranged further on the second side SD2 of the axial direction DD than the second surface 49b of the flange portion 49.

[0073] By disposing the bushing 6 in this manner, the following effects can be achieved. When 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 disposed further on the first side SD1 of the axial direction DD than the first surface 49a of the flange portion 49, the first end portion 6b of the bushing 6 is in contact with the mounting surface 47a of the mounting member 47. This results in the mounting surface 47a of the mounting member 47 and the surface opposite to the mounting surface 47a of the first member 41 in the axial direction DD (the first surface 49a of the flange portion 49) being spaced apart from each other. This can prevent the mounting member 47 and the first member 41 from being in direct contact with each other in the axial direction DD and prevent an impact from the mounting member 47 from being directly transmitted to the first member 41 in the axial direction DD.When 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 located further on the second side SD2 of the axial direction DD than the second surface 49b of the flange portion 49, the following effects can be achieved. When the bushing 6 is held clamped between the head portion 7c of the bolt 7 and the mounting member 47 and the bushing 6 is fixed to the mounting member 47, the head portion 7c of the bolt 7 is prevented from contacting the first member 41. This can prevent an impact from the head portion 7c of the bolt 7 from being directly transmitted to the first member 41.

[0074] The reduction gear 4 of the present embodiment further includes the bolt 7, which is passed through the bushing 6 and serves to fasten the receiving portion 48 to the mounting member 47. The dimension 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 dimension w6 of the head portion 7c of the bolt 7 in the radial direction DF. This also prevents the head portion 7c of the bolt 7 from contacting the first member 41 when the bushing 6 is clamped between the head portion 7c of the bolt 7 and the mounting member 47 and the bushing 6 is fastened to the mounting member 47. This can prevent an impact from the head portion 7c of the bolt 7 from being directly transmitted to the first member 41.Furthermore, when the bushing 6 is clamped between the head portion 7c of the bolt 7 and the mounting member 47 and the bushing 6 is fixed to the mounting member 47, the contact surface of the head portion 7c with the bushing 6 can be ensured. This makes it possible to stably fix the bushing 6 to the mounting member 47 and increase the efficiency with which rotation from the electric motor 3 fixed to the mounting member 47 is input to the reduction gear 4, so that the efficiency with which the reduction gear 4 outputs decelerated rotation can be increased.

[0075] The reduction gear 4 of the present embodiment further includes the second member 42, which is relatively rotatable relative to the first member 41. The first member 41 has the internal teeth 412. The reduction section 45 includes the crankshafts 43 rotatably supported on the second member 42, and the external gears 44, which are provided with the through holes 44d through which the respective crankshafts 43 pass, and have the external teeth 441a and 442a that mesh with the internal teeth 412 of the first member 41. Also with this structure, the reduction gear 4 of the present embodiment can be stably protected from impact.

[0076] The reduction gear 4 of the present embodiment further includes the mounting member 47 arranged such that a gap exists between the mounting member 47 and the first member 41 in the radial direction DF perpendicular to the axis LB of the through-hole 41b, and the bolt 7 passing through the bushing 6 for fastening the receiving 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 larger than the width w9 of the gap between the bushing 6 and the bolt 7 in the radial direction DF. This makes it possible to achieve the following effects. When the mounting member 47 is subjected to an impact, moves in the radial direction DF, and is intended to transmit the impact to the first member 41, it is also conceivable that a surface other than the mounting surface 47a of the mounting member 47 directly contacts the surface of the first member 41.For example, it is also conceivable that the surface 41d of the first element 41 and the surface 47c of the mounting element 47, which in . Fig. 3 opposite to each other in the radial direction DF are in direct contact with each other. Here, when the width w8 is larger than the width w9, when the mounting member 47 is subjected to an impact and moves in the radial direction DF, the contact of the bolt 7 with the buffer portion 5 in the radial direction DF may occur before the surface of the mounting member 47 and the surface of the first member 41 are in direct contact with each other in the radial direction DF. Therefore, the impact can be dampened by the buffer portion 5 before the surface of the mounting member 47 and the surface of the first member 41 are in direct contact with each other in the radial direction DF. This can 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.

[0077] The reduction gear 4 of the present embodiment described above can be used in the construction machine 1. In this case, it can be said that the construction machine 1 includes the reduction gear 4. The construction machine 1 is, for example, an excavator. In the case where the construction machine 1 is an excavator, the reduction gear 4 outputs, for example, rotation used to drive a boom, an arm, a bucket, or the like of the excavator. According to the construction machine 1 including the reduction gear 4 of the present embodiment, the shock transmitted to the first element 41 of the reduction gear 4 can be dampened while the construction machine 1 is driven with the rotation decelerated by the reduction gear 4.

[0078] The present embodiment is described using specific examples; however, the 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 the gist of the embodiment.

[0079] Examples of modifications are described below with reference to the drawings. In the following description and the drawings used in the following description, parts that may be structured similarly to those of the specific examples described above are denoted by the same reference numerals used for corresponding parts of the specific examples described above, and a repeated description is omitted. (Variation 1)

[0080] In the above-described embodiment, the case is described where the second portion 52, which is more easily deformable than the first portion 51 under a certain stress, of the buffer portion 5 is arranged further inward in the radial direction DF than the first portion 51. However, the shape of the buffer portion 5 is not limited to this. Fig. 4 is an enlarged cross-sectional view showing the buffer portion 5 and its surroundings in the cross section of the construction machine 1 of the modification 1. Fig. 4 shows in particular a cross section of the construction machine 1 cut in a plane passing through the axis LB of the through hole 41b.

[0081] In Modification 1, the second portion 52, which is more easily deformed than the first portion 51 under a certain stress, is arranged further inward in the radial direction DF than the first portion 51. Also in this case, the efficiency with which rotation is input to the reduction gear 4 can be increased, while the shock transmitted from the pin 7 to the first member 41 is cushioned by the buffer portion 5 comprising the first portion 51 and the second portion 52, so that the efficiency with which the reduction gear 4 outputs decelerated rotation can be increased.

[0082] Further, in Modification 1, the first portion 51, which is located further inward than the second portion 52 in the radial direction DF, forms the first flange portion 53 and the second flange portion 54. Also in this case, the first flange portion 53 and the second flange portion 54 can prevent the buffer portion 5 from escaping from the through-hole 41b. (Variation 2)

[0083] In the above-described embodiment and modification, an example is described that assumes that the mounting member 47 forms a part of the reduction gear 4. However, the shape of the mounting member 47 is not limited thereto. Fig. 5 shows a cross-sectional view of a configuration example of the construction machine 1 in which the reduction gear 4 of the modification 2 is installed, in an area around the reduction gear 4. Fig. 5 shows in particular a cross-sectional view of the construction machine 1 cut in a plane passing through the axis of rotation LA of a rotation output by the reduction gear 4.

[0084] The mounting member 47 of Modification 2 is a member constituting a part of the construction machine 1 and is particularly large in size compared to the first member 41, the reduction section 45, and the like of the reduction gear 4. The mounting member 47 of Modification 2 is, for example, a member driven by rotation output from the reduction section 45. In the case where the construction machine 1 is an excavator, the mounting member 47 of Modification 2 is, for example, a member for constituting a boom, an arm, a bucket, or the like of the excavator. In Modification 2, the electric motor 3 is directly attached to the mounting member 47.

[0085] In other words, the construction machine 1 of the modification 2 comprises the reduction gear 4 including the reduction portion 45 that decelerates an input rotation, the first member 41 including the receiving portion 48 for receiving the reduction portion 45 and provided with the through-hole 41b serving to fix the receiving portion 48 to the mounting member 47, the buffer portion 5 having a tubular shape and covering the inner wall 41c of the through-hole 41b and including the first portion 51 and the second portion 52 that differ in their deformability under a certain stress, and the bushing 6 provided inside the buffer portion 5 and having a tubular shape, the mounting member 47 arranged such that in the radial direction DF perpendicular to the axis LB of the through-hole 41b, a gap is formed between the mounting member 47 and the first member 41 is present,and the bolt 7, which is guided through the bushing 6 and serves to fasten the receiving portion 48 to the mounting element 47. Also in modification 2, the width w8 of the gap between the first element 41 and the mounting element 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.

[0086] When the width w8 is larger than the width w9, also in the construction machine 1 of the modification 2, like the reduction gear 4 of the above-described embodiment, when the mounting member 47 is subjected to an impact and moves in the radial direction DF, the contact of the pin 7 with the buffer portion 5 in the radial direction DF may occur before the surface of the mounting member 47 and the surface of the first member 41 in the radial direction DF directly contact each other. (Variation 3)

[0087] In the embodiment and modifications described above, an example is described in which the transmission gears 431 are fixed to one end of the crankshafts 43 on the first side SA1 of the rotation axis direction DA. However, the aspect of the reduction gear 4 is not limited to this. Fig. 6 shows a cross-sectional view of a configuration example of the construction machine 1 in which the reduction gear 4 of the modification 3 is installed, in an area around the electric motor 3 and the reduction gear 4. Fig. 6 shows in particular a cross-sectional view of the construction machine 1 cut in a plane passing through the axis of rotation LA of a rotation output by the reduction gear 4.

[0088] In Modification 3, the transmission gear 431 is fixed to one end of the crankshaft 43 on the second side SA2 of the rotational axis direction DA. The transmission gear 431 is arranged on the second side SA2 of the rotational axis direction DA of the first external gear 441 and the second external gear 442. The drive gear 461, provided on the front end portion 46a of the input shaft 46, meshes with the transmission gear 431 on the second side SA2 of the rotational axis direction DA of the first external gear 441 and the second external gear 442.

[0089] Also in the construction machine 1 of the modification 3, the shock transmitted to the reduction gear 4, particularly to the first element 41 and the reduction section 45, which form part of the reduction gear 4, can be dampened by the buffer section 5. Furthermore, torque from the electric motor 3 can be appropriately transmitted to the reduction gear 4. Thus, even in the construction machine 1 of the modification 3, the rotation input from the electric motor 3 can be decelerated and output by the reduction gear 4. (Variation 4)

[0090] In the embodiment and modifications described above, an example is described that the body portion 32 of the electric motor 3 is fixed to the mounting member 47. However, the aspect of fixing the electric motor 3 is not limited thereto. Fig. 7 shows a cross-sectional view of a configuration example of the construction machine 1 in which the reduction gear 4 of the modification 4 is installed, in an area around the electric motor 3 and the reduction gear 4. Fig. 7 shows in particular a cross-sectional view of the construction machine 1 cut in a plane passing through the axis of rotation LA of a rotation output by the reduction gear 4.

[0091] In variation 4, the body portion 32 of the electric motor 3 is attached to the second element 42. In Fig. 7, the construction machine 1 further comprises a coupling element 8 for coupling the electric motor 3 to the second element 42 of the reduction gear 4. The coupling element 8 is fastened to the surface of the second element 42 on the first side SA1 by means of a bolt 81. Furthermore, the body portion 32 of the electric motor 3 is fastened to the surface of the coupling element 8 on the first side SA1 by means of a bolt (not shown). As a result, the body portion 32 of the electric motor 3 is arranged on the first side SA1 of the second element 42 and fastened to the second element 42.

[0092] The coupling element 8 is provided with a through-hole 82 that passes through the coupling element 8 in the rotation axis direction DA. The rotating shaft 31 of the electric motor 3 is inserted into the through-hole 82. A proximal end portion of the input shaft 46 of the reduction gear 4 on the electric motor 3 side (on the first side SA1 of the rotation axis direction DA) is coupled to the rotating shaft 31 of the electric motor 3 in the through-hole 82.

[0093] In Fig. 7, the transmission gear 431 is fixed to one end of the crankshaft 43 on the second side SA2 of the rotational axis direction DA. The transmission gear 431 is arranged on the second side SA2 of 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. Thereby, the drive gear 461 provided on the front end portion 46a of the input shaft 46 meshes with the transmission gear 431 on the second side SA2 of the rotational axis direction DA of the first external gear 441 and the second external gear 442.

[0094] In Fig. 7, the mounting member 47 to which the receiving portion 48 is attached is a member that forms part of the construction machine 1. A portion of the mounting member 47 is located on the first side SA1 of the rotational axis direction DA of the flange portion 49. As a result, the flange portion 49 opposes a portion of the mounting member 47. The portion of the mounting member 47 opposite the flange portion 49 is provided with a screw hole 474 that extends in the rotational axis direction DA and is open on the second side SA2. The reduction gear 4 further includes a fastening auxiliary member 9 arranged on the second side SA2 of the rotational axis direction DA of the first member 41 of the reduction gear 4. The fastening auxiliary member 9 covers the entire reduction portion 45 and the entire first member 41 from the second side SA2 of the rotational axis direction DA.A part of the fastening auxiliary element 9 is located on the second side SA2 of the rotation axis direction DA of the flange portion 49. As a result, the flange portion 49 is opposite a part of the fastening auxiliary element 9. The portion of the fastening auxiliary element 9 opposite the flange portion 49 is provided with a through-hole 91 extending in the rotation axis direction DA and passing through the fastening auxiliary element 9.

[0095] In Fig. 7, the mounting element 47 and the fastening auxiliary element 9 are fastened to the receiving section 48 by means of the bolt 7. Specifically, as in Fig. 7, the bolt 7 inserted into the through hole 91 and the through hole 41b is screwed into the screw hole 474, whereby the mounting member 47 and the fastening auxiliary member 9 can be fixed to the receiving portion 48.

[0096] In Modification 4, the reduction gear 4 also includes the buffer portion 5 covering the inner wall 41c of the through-hole 41b. The reduction gear 4 further includes the bushing 6 provided inside the buffer portion 5. The bolt 7 is inserted through the buffer portion through-hole 5a and passed through the bushing through-hole 6a.

[0097] In Modification 4, the dimension w1 of the bushing 6 is also larger than the dimension w2 of the through-hole 41b. Furthermore, in Modification 4, the dimension w1 of the bushing 6 is also larger than the dimension w3 of the flange portion 49. This prevents the mounting member 47 and the first member 41 from directly contacting each other in the rotational axis direction DA. Furthermore, the fastening auxiliary member 9 and the first member 41 are prevented from directly contacting each other in the rotational axis direction DA.

[0098] Also in the construction machine 1 of the modification 4, the shock transmitted to the reduction gear 4, particularly to the first element 41 and the reduction section 45, which form part of the reduction gear 4, can be dampened by the buffer section 5. Furthermore, when a rotation input from the electric motor 3 is decelerated and output by the reduction gear 4, a torque from the electric motor 3 can be appropriately transmitted. Thus, also in the construction machine 1 of the modification 4, a rotation input from the electric motor 3 can be decelerated and output by the reduction gear 4. (Variation 5)

[0099] In the embodiment and modifications described above, an example is described that the first member 41 is provided with the through hole 41b for fixing the receiving portion 48 to the mounting member 47. However, the shape of the reduction gear 4 and the construction machine 1 is not limited thereto. Fig. 8 shows a cross-sectional view of a configuration example of the construction machine 1 in which the reduction gear 4 of the modification 5 is installed, in an area around the electric motor 3 and the reduction gear 4. Fig. 8 shows in particular a cross-sectional view of the construction machine 1 cut in a plane passing through the axis of rotation LA of a rotation output by the reduction gear 4.

[0100] In variation 5, the first element 41 is not provided with a through-hole 41b. The mounting element 47 is provided with a through-hole 47d, which serves to fasten the receiving portion 48 to the mounting element 47. In this case, the mounting element 47 may be a member that can be considered part of the reduction gear 4. Alternatively, the mounting element 47 may be a member that forms part of the construction machine 1 and is particularly large compared to the first element 41, the reduction portion 45, and the like of the reduction gear 4. Fig. 8, the mounting element 47 is an element that can be considered as part of the reduction gear 4.

[0101] The description given for the through hole 41b provided in the first member 41 in the embodiment and modifications 1 to 4 described above can also be applied to the through hole 47d provided in the mounting member 47 of modification 5 unless there is a contradiction.

[0102] The Fig. The reduction gear 4 shown in Fig. 8 further includes the buffer portion 5, which has a tubular shape and covers an inner wall 47e of the through-hole 47d. The buffer portion 5 includes the first portion 51 and the second portion 52, which differ in their deformability under a certain stress. The reduction gear 4 further includes the bushing 6, which is provided inside the buffer portion 5 and has a tubular shape. The description given for the buffer portion 5, the bushing 6, and the bolt 7 in the embodiment and modifications 1 to 4 described above can also be applied to the buffer portion 5, the bushing 6, and the bolt 7 of modification 5 unless there is a conflict.

[0103] In Modification 5, the portion of the flange portion 49 opposite the mounting member 47 is provided with a screw hole 491 extending in the rotation axis direction DA and open on the second side SA2. In Modification 5, when the bolt 7 is passed through the through-hole 47d and screwed to the screw hole 491 of the flange portion 49, the first member 41 (the housing 41a) is fixed to the mounting member 47, and the receiving portion 48 is fixed to the mounting member 47. The bolt 7 is passed through the buffer portion through-hole 5a and through the bushing through-hole 6a.

[0104] In a Fig.The one-dot chain line marked with a character LC in FIG. 8 is an imaginary line representing an axis LC of the through-hole 47d. A direction in which the through-hole 47d extends (a direction in which the axis LC of the through-hole 47d extends) is referred to as an axial direction DG. A direction perpendicular to the axis LC of the through-hole 47d is referred to as a radial direction DH. In Modification 5, a dimension w10 of the bushing 6 in the axial direction DG in which the through-hole 47d extends is larger than a dimension w11 of the through-hole 47d in the axial direction DG. This allows the bushing 6 to be arranged to protrude from the through-hole 47d on both sides of the through-hole 47d. This results in the mounting element 47 and the first element 41 being spaced apart from each other in the axial direction DG.This can prevent a shock from being transmitted directly from the mounting element 47 to the first element 41 in the axial direction DG.

[0105] Although not shown, the mounting member 47 of Modification 5 may include a portion opposite to the first member 41 in the radial direction DH. In this case, the mounting member 47 is arranged such that a gap exists 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. Specifically, 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. Therefore, an 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 directly contact each other in the radial direction DH.This can prevent a strong shock from being transmitted from the mounting element 47 to the first element 41 due to direct contact between the surface of the mounting element 47 and the surface of the first element 41 in the radial direction DH.

[0106] Also in the construction machine 1 of the modification 5, the shock transmitted to the reduction gear 4, particularly to the first element 41 and the reduction section 45, which form part of the reduction gear 4, can be dampened by the buffer section 5. Furthermore, torque from the electric motor 3 can be appropriately transmitted to the reduction gear 4. Thus, even in the construction machine 1 of the modification 5, the rotation input from the electric motor 3 can be decelerated and output by the reduction gear 4.

[0107] Among the embodiments disclosed in this specification, with respect to a component consisting of multiple objects, the multiple objects may be integrated, and conversely, a component consisting of one object may be divided into multiple objects. Regardless of whether integration occurs, it is sufficient if the design is such that the purpose of the invention is achieved.

[0108] The aspects of the present invention are not limited to the individual embodiments described above, but include various modifications conceivable by those skilled in the art, and the effects of the present invention are also not limited to the above-described content. That is, various additions, changes, and partial deletions can be made without departing from the conceptual spirit and gist of the present invention, which are derived from the content defined in the claims and their equivalents. List of reference symbols 1 construction machine 2 drive machine 3 electric motor 31 Rotating shaft 4 reduction gears 41 first element 41b Through hole 42 second element 43 Crankshaft 44 External gear 45 Reduction section 47 Mounting element 48 Recording section 49 Flange section 5 Buffer section 51 first section 52 second section 6 socket 7 bolts QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2013 / 114451

[0004]

Claims

[1] Reduction gear 4, comprising: a reduction section 45 which slows down an input rotation; a first element 41 comprising a receiving portion 48 for receiving the reduction portion 45 and provided with a through-hole 41b for fastening the receiving portion 48 to a mounting element 47; and a buffer portion 5 having a tubular shape and covering an inner wall 41c of the through-hole 41b and comprising a first portion 51 and a second portion 52 which differ in their deformability under a certain stress. [2] The reduction gear 4 according to claim 1, further comprising a bushing 6 provided inside the buffer portion 5 and having a tubular shape. [3] The reduction gear 4 according to claim 2, wherein a dimension w1 of the bushing 6 in an axial direction DD in which the through hole 41b extends is larger than a dimension w2 of the through hole 41b in the axial direction DD. [4] The reduction gear 4 according to claim 2, wherein the first member 41 further comprises a flange portion 49 projecting from the receiving portion 48 in the direction crossing the axial direction DD in which the through hole 41b extends, and facing the mounting member 47, wherein the flange portion 49 is provided with the through hole 41b, and wherein the dimension w1 of the bushing 6 in the axial direction DD is greater than a dimension w3 of the flange portion 49 in the axial direction DD. [5] A reduction gear 4 according to claim 2, further comprising a bolt 7 passed through the bushing 6 and for fixing the receiving portion 48 to the mounting member 47, wherein a dimension w7 of the bushing 6 in a radial direction DF perpendicular to an axis LB of the through-hole 41b is greater than or equal to a dimension w6 of a head portion 7c of the bolt 7 in the radial direction DF. [6] Reduction gear 4 according to claim 1, further comprising a second element 42 relatively rotatable relative to the first element 41, wherein the first element 41 has internal teeth 412, and wherein the reduction portion 45 includes a crankshaft 43 rotatably supported on the second member 42, and an external gear 44 provided with a through-hole 44d through which the crankshaft 43 passes, and having external teeth 441a and 442a engaging with the internal teeth 412 of the first member 41. [7] Reduction gear 4 according to claim 2, further comprising: the mounting member 47 arranged such that a gap exists between the mounting member 47 and the first member 41 in the radial direction DF perpendicular to the axis LB of the through-hole 41b; and the bolt 7, which is guided through the bushing 6 and serves to fasten the receiving section 48 to the mounting element 47, wherein a width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is greater than a width w9 of a gap between the bushing 6 and the bolt 7 in the radial direction DF. [8] Reduction gear 4, comprising: a reduction section 45 which slows down an input rotation; a first member 41 including a receiving portion 48 for receiving the reducing portion 45; a mounting member 47 to which the receiving portion 48 is attached and which is provided with a through-hole 41b for attaching the receiving portion 48 to the mounting member 47; and a buffer portion 5 having a tubular shape and covering an inner wall 41c of the through-hole 41b and comprising a first portion 51 and a second portion 52 which differ in their deformability under a certain stress. [9] Construction machine 1 comprising the reduction gear 4 according to one of claims 1 to 8. [10] Construction machine 1, comprising: a reduction gear 4 including a reduction portion 45 that decelerates an input rotation, a first member 41 including a receiving portion 48 for receiving the reduction portion 45 and provided with a through-hole 41b for fixing the receiving portion 48 to a mounting member 47, a buffer portion 5 having a tubular shape and covering an inner wall 41c of the through-hole 41b and including a first portion 51 and a second portion 52 that differ in deformability under a certain stress, and a bushing 6 provided inside the buffer portion 5 and having a tubular shape; the mounting member 47 arranged such that a gap exists between the mounting member 47 and the first member 41 in a radial direction DF perpendicular to an axis LB of the through-hole 41b; and a bolt 7 which is guided through the bushing 6 and serves to fasten the receiving section 48 to the mounting element 47, wherein a width w8 of the gap between the first member 41 and the mounting member 47 in the radial direction DF is greater than a width w9 of a gap between the bushing 6 and the bolt 7 in the radial direction DF. [11] Construction machine 1, comprising: a reduction gear 4 including a reduction portion 45 that slows down an input rotation, and a first member 41 including a receiving portion 48 for receiving the reduction portion 45; a mounting member 47 to which the receiving portion 48 is fixed and which is provided with a through hole 41b for fixing the receiving portion 48 to the mounting member 47; a buffer portion 5 having a tubular shape and covering an inner wall 41c of the through-hole 41b and including a first portion 51 and a second portion 52 which differ in deformability under a certain stress; a bushing 6 provided inside the buffer portion 5 and having a tubular shape; and a bolt 7 which is guided through the bushing 6 and serves to fasten the receiving section 48 to the mounting element 47.

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