Reducing mechanism and robot

Abstract

The speed reduction mechanism is provided with: an output hypoid gear having an annular gear section centered on an output axis; an input hypoid gear extending along an input axis extending along a plane orthogonal to the output axis, and meshing with the gear portion; a first bearing that supports the base end side of the input hypoid gear on the radial outer side of the gear part so as to be rotatable about the input axis; and a second bearing that rotatably supports the front end side of the input hypoid gear on the radial inner side of the gear part around the input axis, in which the output hypoid gear has a recessed portion on the radial inner side of the gear part, the recessed portion being recessed with respect to the gear part in the output axis direction. A part of the radial outer side of the second bearing is arranged in the concave part.

Description

Technical Field

[0001] The present disclosure relates to a speed reduction mechanism and a robot. Background Art

[0002] As a speed reduction mechanism for a robot, a speed reduction mechanism having an input hypoid gear and an output hypoid gear meshing with the input hypoid gear is known (for example, refer to Patent Document 1). Since hypoid gears can increase the reduction ratio and have low noise, they are effective as a speed reduction mechanism for robots that require high torque and quietness.

[0003] In a speed reduction mechanism having hypoid gears, if the reduction ratio is increased, the diameter of the output hypoid gear becomes larger and the diameter of the input hypoid gear becomes smaller, so the rigidity of the input hypoid gear is reduced. In addition, since the axes of the input hypoid gear and the output hypoid gear are eccentric without crossing, the front end portion of the input hypoid gear approaches the gear portion of the output hypoid gear. Therefore, the input hypoid gear is usually supported by a bearing on the radially outer side of the output hypoid gear and is supported in a cantilever shape such that only the gear portion protrudes to a position overlapping the output hypoid gear.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-93489. Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] In a structure in which a small-diameter and low-rigidity input hypoid gear is supported in a cantilever shape, when torque is applied, the input hypoid gear sometimes deforms, resulting in deterioration of the meshing accuracy. Therefore, a speed reduction mechanism and a robot are desired that can suppress deformation of the input hypoid gear, maintain the meshing accuracy, and prevent the generation of angular transmission error and noise even when ensuring a large reduction ratio.

[0009] Technical Means for Solving the Technical Problem

[0010] One aspect of the present disclosure is a speed reduction mechanism including: an output hypoid gear having an annular gear portion centered on an output axis; an input hypoid gear extending along an input axis extending in a plane orthogonal to the output axis and meshing with the gear portion; a first bearing supporting a proximal end side of the input hypoid gear rotatably about the input axis on a radially outer side of the gear portion; and a second bearing supporting a distal end side of the input hypoid gear rotatably about the input axis on a radially inner side of the gear portion, wherein the output hypoid gear has a recess on a radially inner side of the gear portion, the recess being recessed with respect to the gear portion in the output axis direction, and a radially outer portion of the second bearing is disposed within the recess. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a perspective view of a robot having the speed reduction mechanism according to the first embodiment of the present disclosure.

[0012] Figure 2 is a partial cross-sectional view of the speed reduction mechanism according to the first embodiment of the present disclosure.

[0013] Figure 3 is Figure 2 a longitudinal cross-sectional view of the speed reduction mechanism indicated by the ABOC arrow.

[0014] Figure 4 is Figure 2 a partial enlarged view of the speed reduction mechanism.

[0015] Figure 5 is for explaining Figure 3 a partial enlarged view of the indicated position and the disengaged position of the bracket portion in the speed reduction mechanism.

[0016] Figure 6 is a partial enlarged view of the bracket portion of the speed reduction mechanism as viewed from the input axis side Figure 2 thereof. DETAILED DESCRIPTION

[0017] Hereinafter, the speed reduction mechanism 10 and the robot 1 according to one embodiment of the present disclosure will be described with reference to the drawings. The robot 1 according to the present embodiment is, for example, a vertical six-axis articulated robot.

[0018] As Figure 1 shown, the robot 1 has a base 2 and a rotating body 3. The base 2 is fixed to a set surface such as the ground, and the rotating body 3 is supported so as to be rotatable about a vertical first axis J1 with respect to the base 2. Further, the robot 1 also has a first arm 4, and the first arm 4 is supported so as to be rotatable about a horizontal second axis J2 with respect to the rotating body 3.

[0019] Further, the robot 1 also has a second arm 5 and a three-axis wrist unit 6. The second arm 5 is supported in such a way that it can rotate relative to the first arm 4 about a third axis J3 parallel to the second axis J2. The wrist unit 6 is mounted at the front end of the second arm 5. The wrist unit 6 has a first wrist element 7, and the first wrist element 7 is supported in such a way that it can rotate relative to the second arm 5 about a fourth axis J4 extending in a plane orthogonal to the third axis J3.

[0020] In addition, the wrist unit 6 also has a second wrist element 8, and the second wrist element 8 is supported in such a way that it can rotate relative to the first wrist element 7 about a fifth axis J5 orthogonal to the fourth axis J4. Further, the wrist unit 6 also has a third wrist element 9, and the third wrist element 9 is supported in such a way that it can rotate relative to the second wrist element 8 about a sixth axis J6. The sixth axis J6 extends along a plane orthogonal to the fifth axis J5 and containing the fourth axis J4.

[0021] The rotating body 3, the first arm 4, the second arm 5, the first wrist element 7, the second wrist element 8, and the third wrist element 9 are respectively driven by reducing the rotation of the shaft of the servo motor by using a speed reduction mechanism 10.

[0022] For example, the speed reduction mechanism 10 according to the present embodiment is provided in at least one of the joint portions between the first arm 4 and the second arm 5 and the joint portion between the first wrist element 7 and the second wrist element 8. Here, the speed reduction mechanism 10 provided in the joint portion between the first wrist element 7 and the second wrist element 8 will be described as an example.

[0023] As Figure 3 shown, the speed reduction mechanism 10 has a housing 11, a cover 12, two input hypoid gears 13, 14, and two output hypoid gears 15, 16. The housing 11 and the cover 12 constitute the outer shell of the first wrist element 7. The two input hypoid gears 13, 14 and the two output hypoid gears 15, 16 are housed in the housing 11. The first input hypoid gear (input hypoid gear) 13 is arranged in such a way that it can rotate about an input axis JI1. The input axis JI1 extends along a plane orthogonal to the fifth axis J5 and parallel to the fourth axis J4. The second input hypoid gear (other input hypoid gear) 14 is also arranged in such a way that it can rotate about an input axis JI2. The input axis JI2 extends along a plane orthogonal to the fifth axis J5 and parallel to the fourth axis J4.

[0024] The first output hypoid gear (output hypoid gear) 15 and the second output hypoid gear (other output hypoid gear) 16 are coaxially arranged so as to be rotatable about a fifth axis (output axis) J5. The first output hypoid gear 15 and the second output hypoid gear 16 each have an annular gear portion 17, 18 centered on the fifth axis J5. Each gear portion 17, 18 gently inclines along a conical surface with a larger apex angle. The first output hypoid gear 15 and the second output hypoid gear 16 have recesses 19, 20 on the radially inner sides of their respective gear portions 17, 18. The recesses 19, 20 are formed as circles centered on the fifth axis J5 and recess along the direction of the fifth axis J5 from the front end.

[0025] A part of the gear portion 17 of the first output hypoid gear 15 in the thickness direction is received in the recess 20 of the second output hypoid gear 16. Thus, the gear portion 17 of the first output hypoid gear 15 and the gear portion 18 of the second output hypoid gear 16 are arranged side by side on the inner and outer sides in the radial direction. In other respects, the recess 19 of the first output hypoid gear 15 is open.

[0026] The second output hypoid gear 16 is supported by a bearing 21 on the housing 11 so as to be rotatable about the fifth axis J5. The second wrist element 8 has a first part 22 and a second part 23. The first part 22 is fixed to the second output hypoid gear 16 by bolts (not shown), and the second part 23 is detachably fixed to the first part 22 by bolts (not shown). The first part 22 has a through hole 24 that extends along the fifth axis J5. The second part 23 has a through hole 25 that extends along a sixth axis J6.

[0027] The first output hypoid gear 15 has a shaft portion 26, and the shaft portion 26 is inserted into the through hole 24 of the first part 22 of the second output hypoid gear 16. The shaft portion 26

[0028] is supported by the second output hypoid gear 16 through a bearing 27 arranged between it and the through hole 24 so as to be rotatable about the fifth axis J5. Thus, the first output hypoid gear 15 is also indirectly supported by the bearing 27 and the second output hypoid gear 16 on the housing 11 so as to be rotatable about the fifth axis J5.

[0029] A bevel gear 28 is fixed to the front end of the shaft portion 26 of the first output hypoid gear 15. The bevel gear 28 is arranged in the space formed between the first part 22 and the second part 23 of the second wrist element 8.

[0030] In the through-hole 25 of the second part 23 of the second wrist element 8, the third wrist element 9 is supported by a bearing 29 so as to be rotatable about a sixth axis J6. A bevel gear 30 is also fixed to one end of the third wrist element 9. In the space between the first part 22 and the second part 23 of the second wrist element 8, a bevel gear 28 fixed to the first output hypoid gear 15 meshes with a bevel gear 30 fixed to the third wrist element 9.

[0031] The first input hypoid gear 13 is a rod-shaped member extending along an input axis JI1 parallel to the fourth axis J4, and has a gear portion 31 that meshes with the gear portion 17 of the first output hypoid gear 15. In addition, the first input hypoid gear 13 has a first shaft portion 32 on the proximal end side in the direction of the input axis JI1 of the gear portion 31, and a second shaft portion 33 on the distal end side in the direction of the input axis JI1 of the gear portion 31.

[0032] At the first shaft portion 32 on the proximal end side, the first input hypoid gear 13 is mounted on a cylindrical sleeve 35 by a pair of bearings (first bearings) 34 so as to be rotatable about the input axis JI1. The pair of bearings 34 are, for example, tapered roller bearings. The first shaft portion 32 has an external thread 36 and a stepped portion 37. By clamping the sleeve 35 between the outer rings of the pair of bearings 34 and using a nut 38 fastened to the external thread 36, the inner rings of the pair of bearings 34 are brought closer to each other in the direction of the input axis JI1, thereby applying preload to the bearings 34.

[0033] The sleeve 35 has a fitting portion 40 and a flange 42. The fitting portion 40 fits into a fitting hole 39 provided in the housing 11 on the radially outer side of the second output hypoid gear 16, and the flange 42 abuts against a contact surface 41 of the housing 11. The first input hypoid gear 13 is positioned in a direction orthogonal to the input axis JI1 by fitting the fitting portion 40 into the fitting hole 39, and is positioned in the direction along the input axis JI1 by bringing the flange 42 into contact with the contact surface 41. If necessary, by sandwiching a gasket between the contact surface 41 and the flange 42, the position of the first input hypoid gear 13 in the direction of the input axis JI1 can be appropriately adjusted.

[0034] In addition, as Figure 4 shown, the second shaft portion 33 of the first input hypoid gear 13 is formed in a cylindrical shape with a certain diameter dimension. As will be described later, the second shaft portion 33 is supported by a needle bearing (second bearing) 43 mounted on the cover 12 so as to be rotatable about the input axis JI1. That is, the first input hypoid gear 13 is supported in a double-support beam shape on both sides of the gear portion 17 of the first output hypoid gear 15 by the bearing 34 on the proximal end side of the gear portion 31 and the needle bearing 43 on the distal end side.

[0035] In addition, as Figure 2 shown, the front end position of the second shaft portion 33 is arranged on the base end side in the direction closer to the input axis JI1 than the plane including the fifth axis J5 and orthogonal to the fourth axis J4 (hereinafter referred to as the reference plane).

[0036] On the other hand, the second input hypoid gear 14 is also a rod-shaped member extending along the input axis JI2 parallel to the fourth axis J4, and has a gear portion 44 meshing with the gear portion 18 of the second output hypoid gear 16. In addition, the second input hypoid gear 14 has a shaft portion 45 on the base end side in the direction of the input axis JI2 of the gear portion 44.

[0037] At the shaft portion 45 on the base end side, the second input hypoid gear 14 is mounted on the cylindrical sleeve 47 by a pair of bearings 46 so as to be rotatable about the input axis JI2. The pair of bearings 46 are, for example, tapered roller bearings. The shaft portion 45 has an external thread 48 and a stepped portion 49. By clamping the sleeve 47 between the outer rings of the pair of bearings 46 and using a nut 50 fastened to the external thread 48, the inner rings of the pair of bearings 46 are brought closer to each other in the direction of the input axis JI2, thereby applying preload to the bearings 46.

[0038] The sleeve 47 has a fitting portion 51 and a flange 52. The fitting portion 51 fits into a fitting hole provided in the housing 11 on the radially outer side of the second output hypoid gear 16, and the flange 52 abuts against the abutting surface of the housing 11. The second input hypoid gear 14 is positioned in the direction orthogonal to the input axis JI2 by fitting the fitting portion 51 into the fitting hole, and is positioned in the direction along the input axis JI2 by abutting the flange 52 against the abutting surface. If necessary, by sandwiching a gasket between the abutting surface and the flange 52, the position of the second input hypoid gear 14 in the direction of the input axis JI2 can be appropriately adjusted.

[0039] Thus, the second input hypoid gear 14 is supported in a cantilever shape only on the radially outer side of the gear portion 18 of the second output hypoid gear 16 by the bearing 46 on the base end side of the gear portion 44.

[0040] As Figure 3 shown, the housing 11 is provided with an opening 11a, and the opening 11a opens toward the opposite side of the output hypoid gears 15 and 16 across the fourth axis J4. Around the opening 11a, a seating surface 53 extending along a plane intersecting the fifth axis J5 is provided.

[0041] The seat surface 53 is inclined at a prescribed angle about a line that is orthogonal to both the fourth axis J4 and the fifth axis J5 with respect to a plane orthogonal to the fifth axis J5. That is, the seat surface 53 is inclined in the direction approaching the second wrist member 8 along the fifth axis J5 as it extends from the base end side toward the front end side along the fourth axis J4. A plurality of threaded holes (not shown) are formed at circumferentially spaced intervals on the seat surface 53.

[0042] The cover 12 has a mounting surface 54 and a bracket portion 55. The mounting surface 54 abuts against the seat surface 53, and when the mounting surface 54 abuts against the seat surface 53, the bracket portion 55 is disposed inside the housing 11. The cover 12 has a plurality of through holes (not shown) and an O-ring groove 56. When the mounting surface 54 abuts against the seat surface 53, the plurality of through holes are disposed at positions that coincide with the threaded holes of the seat surface 53. The O-ring groove 56 faces the seat surface 53 over the entire circumference at a position closer to the inside than all of the through holes. An O-ring (sealing member) 57 is housed in the O-ring groove 56, and when the mounting surface 54 of the cover 12 abuts against the seat surface 53, the entire circumference of the opening 11a can be sealed by the O-ring 57.

[0043] The bracket portion 55 is a protruding portion that projects from one surface of the cover 12. A fitting hole 58 that penetrates the bracket portion 55 is provided near the front end of the bracket portion 55, and the outer ring of the needle bearing 43 is fitted in the fitting hole 58. As Figure 6 shown, as the needle bearing 43, a needle bearing having an outer ring 59 and a plurality of rollers 61 held by a retainer 60 and not having an inner ring is used.

[0044] The thickness dimension in the axial direction of the fitting hole 58 near the front end of the bracket portion 55 is set to be smaller than the length dimension of the outer ring 59 of the needle bearing 43. As a result, only a part of the length direction of the outer ring 59 of the needle bearing 43 on the side away from the gear portion 31 of the first input hypoid gear 13 is fitted in the fitting hole 58, and the remaining part on the side closer to the gear portion 31 is exposed outside the fitting hole 58. The fitting length of the outer ring 59 of the needle bearing 43 in the fitting hole 58 is preferably greater than half of the total length of the outer ring 59.

[0045] In addition, the bracket portion 55 has a recess 62 that locally recesses the outer surface on the side closer to the gear portion 31 of the first input hypoid gear 13. The recess 62 is formed, for example, by machining such as cutting the outer surface of the bracket portion 55 along a surface parallel to the axis of the fitting hole 58.

[0046] When the cover 12 is mounted on the housing 11 such that the mounting surface 54 abuts against the seat surface 53, the bracket portion 55 is disposed at a position where the front end extends into the recess 19 of the first output hypoid gear 15. At this time, in Figure 6In the illustrated example, a part of the front end of the bracket portion 55 is disposed within the concave portion 19 of the first output hypoid gear 15, and a part of the outer ring 59 of the needle roller bearing 43 mounted on the bracket portion 55 is also disposed therein. Further, at this time, the inscribed circles of all the rollers 61 of the needle roller bearing 43 are disposed outside the concave portion 19.

[0047] Further, when the cover 12 is mounted on the housing 11 such that the mounting surface 54 is in close contact with the seat surface 53, the bracket portion 55 is disposed at a position closer to the proximal end side in the direction of the input axis JI1 than the reference plane. Thus, the front end side of the second shaft portion 33 of the first input hypoid gear 13 is supported by the needle roller bearing 43 fitted in the fitting hole 58 so as to be rotatable about the input axis JI1.

[0048] At the proximal ends of the first input hypoid gear 13 and the second input hypoid gear 14, gears 63, 64 that constitute a power transmission mechanism for transmitting power from the servo motor are fixed.

[0049] Next, the operation of the speed reduction mechanism 10 and the robot 1 configured as described above will be described. According to the speed reduction mechanism 10 according to the present embodiment, the first input hypoid gear 13 is supported in a double support beam shape on both sides in the direction of the input axis JI1 with the gear portion 31 meshing with the first output hypoid gear 15 interposed therebetween. Thus, even if the diameter of the first input hypoid gear 13 is reduced, deformation of the first input hypoid gear 13 when torque is applied can be suppressed, the meshing accuracy can be maintained, and angular transmission errors and noise can be prevented from occurring.

[0050] That is, by reducing the diameter of the first input hypoid gear 13, there is an advantage that the diameter of the first output hypoid gear 15 is not increased, and a large reduction ratio can be ensured while achieving miniaturization. In this case, the smaller the diameter of the first input hypoid gear 13, the closer the input axis JI1 is to the first output hypoid gear 15 in the direction of the fifth axis J5.

[0051] According to the present embodiment, a part of the outer ring 59 of the needle roller bearing 43 that supports the second shaft portion 33 is disposed within the concave portion 19 of the first output hypoid gear 15. Thus, with respect to the second shaft portion 33, even if its outer peripheral surface is infinitely close to the first output hypoid gear 15 in the direction of the fifth axis J5, it can be supported by the needle roller bearing 43 so as to be rotatable about the input axis JI1.

[0052] In addition, according to the present embodiment, by using a needle roller bearing 43 to support the second shaft portion 33, the thickness dimension of the needle roller bearing 43 in the radial direction can be reduced. Further, by using a needle roller bearing without an inner ring as the needle roller bearing 43, the thickness dimension of the needle roller bearing 43 in the radial direction can be further reduced. If the position of the second shaft portion 33 in the direction of the fifth axis J5 is not changed, the smaller the thickness dimension of the needle roller bearing 43 in the radial direction, the smaller the portion of the needle roller bearing 43 disposed in the concave portion 19 of the first output hypoid gear 15 can be maintained.

[0053] In Figure 6 In the illustrated example, the concave portion 19 of the first output hypoid gear 15 has a depth dimension that is slightly larger than the sum of the thickness dimension of the outer ring 59 of the needle roller bearing 43 in the radial direction and the wall thickness dimension around the fitting hole 58 of the bracket portion 55. By suppressing the thickness dimension of the needle roller bearing 43 in the radial direction, the depth of the concave portion 19 can be made shallower, and the gear portion 17 of the first output hypoid gear 15 can be made thinner, so as to achieve the thinning of the housing 11.

[0054] In addition, according to the present embodiment, the outer ring 59 of the needle roller bearing 43 that supports the second shaft portion 33 is only fitted into the fitting hole 58 of the bracket portion 55 on the front end side of the second shaft portion 33. Thereby, while the bracket portion 55 is moved away from the gear portion 31 of the first input hypoid gear 13 in the direction of the input axis JI1, the support position where the second shaft portion 33 is supported by the needle roller bearing 43 can be made closer to the gear portion 31.

[0055] In the direction orthogonal to both the fourth axis J4 and the fifth axis J5, the width dimension of the concave portion 19 is the largest at the position of the reference plane and becomes smaller as it is farther away from the reference plane in the direction of the input axis JI1. Since the second shaft portion 33 is disposed at a position closer to the base end side of the input axis JI1 than the reference plane, by moving the bracket portion 55 away from the gear portion 31, it can be disposed in the concave portion 19 at a position where the width dimension near the reference plane is larger.

[0056] Further, a recess 62 is provided on the outer surface of the bracket portion 55 on the side closer to the gear portion 31 of the first input hypoid gear 13. By locally reducing the diameter of the bracket portion 55 at the position closer to the gear portion 31 by using the recess 62, interference between the bracket portion 55 and the gear portion 31 can be suppressed, and at the same time, the support strength of the bracket portion 55 for the needle roller bearing 43 can be improved. Further, thereby, the bracket portion 55 can be disposed at a position farther away from the reference plane, so that the second shaft portion 33 can be supported as much as possible on the base end side.

[0057] In addition, according to the present embodiment, the outer ring 59 of the needle bearing 43 on the proximal end side of the second shaft portion 33 is exposed in the support portion 55. As a result, the needle bearing 43 can be arranged in the recess 19 with a smaller width dimension at a position farther from the reference plane. As a result, it is possible to ensure the gap between the support portion 55 and the needle bearing 43 and the gear portion 31, and at the same time, the support position where the second shaft portion 33 is supported by the needle bearing 43 can be made closer to the proximal end portion of the second shaft portion 33, thereby reducing the stress generated at the proximal end portion.

[0058] In this case, the outer ring 59 of the needle bearing 43 is fitted into the fitting hole 58 of the support portion 55 over a length greater than half of the axial length. As a result, the needle bearing 43 is supported by the support portion 55 with sufficient strength. In addition, as long as the support strength can be sufficiently ensured, the fitting length of the outer ring 59 of the needle bearing 43 fitted into the fitting hole 58 may also be a length less than or equal to half of the axial length of the outer ring 59.

[0059] In addition, according to the present embodiment, when the mounting surface 54 of the cover 12 is in close contact with the seat surface 53 of the housing 11, as Figure 5 shown by the solid line, the support portion 55 and the needle bearing 43 are arranged at a support position for rotatably supporting the second shaft portion 33. At this support position, a part of the front end of the support portion 55 is arranged in the recess 19 at a position offset from the reference plane toward the proximal end side of the input axis JI1.

[0060] In addition, when the support portion 55 is arranged at the support position, a space is ensured on the side closer to the reference plane than the support portion 55, allowing the support portion 55 to move along the direction of the input axis JI1 and having no components arranged in the recess 19. In this space, the width dimension of the recess 19 is equal to or greater than the width dimension of the recess 19 at the support position. Therefore, as Figure 5 shown by the solid line at the support position and the dotted line at the disengaged position, the support portion 55 can move along the input axis JI1 without contacting the gear portion 31.

[0061] The above has described the embodiments of the present disclosure in detail, but the present disclosure is not limited to the above embodiments. These embodiments can be subjected to various additions, replacements, changes, partial deletions, etc. within the scope of not departing from the gist of the present disclosure or the idea and gist of the present invention derived from the content described in the claims and its equivalents. For example, in the above embodiments, the order of each action and the order of each process are shown only as an example and are not limited thereto.

[0062] Regarding the above embodiments and variations, the following additional notes are further disclosed.

[0063] (Supplementary Note 1) A speed reduction mechanism, comprising: an output hypoid gear having an annular gear portion centered on an output axis; an input hypoid gear extending along an input axis extending in a plane orthogonal to the output axis and meshing with the gear portion; a first bearing supporting the proximal end side of the input hypoid gear rotatably about the input axis on the radially outer side of the gear portion; and a second bearing supporting the distal end side of the input hypoid gear rotatably about the input axis on the radially inner side of the gear portion, wherein the output hypoid gear has a recess on the radially inner side of the gear portion, the recess being recessed with respect to the gear portion in the output axis direction, and a part of the radially outer side of the second bearing is disposed within the recess.

[0064] (Supplementary Note 2) The speed reduction mechanism according to Supplementary Note 1, wherein the second bearing is a needle bearing.

[0065] (Supplementary Note 3) The speed reduction mechanism according to Supplementary Note 2, wherein the second bearing does not have an inner ring.

[0066] (Supplementary Note 4) The speed reduction mechanism according to any one of Supplementary Notes 1 to 3, further comprising: a housing accommodating at least a part of the input hypoid gear and the output hypoid gear; and a cover closing an opening provided in the housing in an openable and closable manner, wherein the second bearing is mounted inside the cover.

[0067] (Supplementary Note 5) The speed reduction mechanism according to Supplementary Note 4, wherein the housing has a seating surface extending along a plane intersecting the output shaft and surrounding the opening, the cover has a mounting surface capable of closely adhering to the seating surface, and the speed reduction mechanism further comprises a sealing member disposed between the seating surface and the mounting surface and sealing the opening.

[0068] (Supplementary Note 6) The speed reduction mechanism according to Supplementary Note 5, wherein the seating surface is inclined in the direction of the input axis from the proximal end side toward the distal end side and in the direction of approaching the output hypoid gear along the output axis. [[ID=**16**]] [[ID=**17**]]

[0069] (Supplementary Note 7) The speed reduction mechanism according to any one of Supplementary Notes 4 to 6, wherein the cover includes a support portion holding an outer ring of the second bearing, and the recess has a space allowing the support portion to move in the direction of the input axis between a position where the distal end side is fitted to the second bearing and a position where the fitting is disengaged.

[0070] (Supplementary Note 8) The speed reduction mechanism according to Supplementary Note 7, wherein the support portion holds only an axially partial portion of the outer ring located on a side closer to the distal end side than the input hypoid gear. It should be noted that the content in tags and

[0069] remains unchanged as they are 7 - digit tags. If there are specific requirements for these tags in the actual context, further processing may be needed according to those requirements.

[0071] (Supplementary Note 9) The speed reduction mechanism according to Supplementary Note 7 or 8 further includes: a recess formed by locally recessing an outer surface of a position where the bracket portion approaches the gear portion.

[0072] (Supplementary Note 10) The speed reduction mechanism according to any one of Supplementary Notes 1 to 9 further includes: another output hypoid gear coaxially disposed radially outside the output hypoid gear; and another input hypoid gear meshing with the another output hypoid gear.

[0073] (Supplementary Note 11) A robot includes the speed reduction mechanism according to any one of Supplementary Notes 1 to 10.

[0074] Description of Reference Numerals

[0075] 1: Robot

[0076] 10: Speed reduction mechanism

[0077] 11: Housing

[0078] 11a: Opening

[0079] 12: Cover

[0080] 13: First input hypoid gear (input hypoid gear)

[0081] 14: Second input hypoid gear (another input hypoid gear)

[0082] - 15: First output hypoid gear (output hypoid gear)

[0083] 16: Second output hypoid gear (another output hypoid gear)

[0084] 17: Gear portion

[0085] 19: Concave portion

[0086] 34: Bearing (first bearing)

[0087] 43: Needle bearing (second bearing)

[0088] 53: Seating surface

[0089] 54: Mounting surface

[0090] 55: Bracket portion

[0091] 57: O-ring (sealing member)

[0092] 59: Outer ring

[0093] 62: Recess

[0094] JI1: Input axis

[0095] J5: Fifth axis (output axis)

Claims

1. A reduction mechanism, comprising: An output hypoid gear having an annular gear portion centered on an output axis; An input hypoid gear extending along an input axis extending in a plane orthogonal to the output axis and meshing with the gear portion; A first bearing supporting the proximal end side of the input hypoid gear in a rotatable manner about the input axis on the radially outer side of the gear portion; And A second bearing supporting the distal end side of the input hypoid gear in a rotatable manner about the input axis on the radially inner side of the gear portion, wherein the output hypoid gear has a recess on the radially inner side of the gear portion, the recess being recessed with respect to the gear portion in the output axis direction, A part of the radially outer side of the second bearing is disposed within the recess.

2. The reduction mechanism according to claim 1, wherein The second bearing is a needle bearing.

3. The reduction mechanism according to claim 2, wherein The second bearing does not have an inner ring.

4. The reduction mechanism according to any one of claims 1 to 3, further comprising: A housing accommodating at least a part of the input hypoid gear and the output hypoid gear; And A cover closing the opening provided in the housing in an openable and closable manner, wherein the second bearing is mounted inside the cover.

5. The reduction mechanism according to claim 4, wherein The housing has a seating surface extending in a plane intersecting the output axis and surrounding the opening, The cover has a mounting surface capable of closely adhering to the seating surface, The reduction mechanism further includes a sealing member disposed between the seating surface and the mounting surface and sealing the opening.

6. The reduction mechanism according to claim 5, wherein The seating surface is inclined from the proximal end side toward the distal end side along the input axis in a direction approaching the output hypoid gear along the output axis.

7. The reduction mechanism according to any one of claims 4 to 6, wherein The cover includes a bracket portion holding the outer ring of the second bearing, and the recess has a space allowing the bracket portion to move in the direction of the input axis between a position where the distal end side is fitted to the second bearing and a position where the fitting is disengaged.

8. The reduction mechanism according to claim 7, wherein The bracket portion only holds an axially partial portion of the outer ring located at a position closer to the distal end side than the input hypoid gear.

9. The reduction mechanism according to claim 7 or 8, further comprising: A depression formed by locally depressing the outer surface at a position where the bracket portion approaches the gear portion.

10. The reduction mechanism according to any one of claims 1 to 9, further comprising: Another output hypoid gear coaxially disposed on the radially outer side of the output hypoid gear; And Another input hypoid gear meshing with the another output hypoid gear.

11. A robot having the reduction mechanism according to any one of claims 1 to 10.

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