JP2017110768A - Gear reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear reduction device which can improve the durability of an inner tooth gear by suppressing a stress concentration.SOLUTION: An inner tooth gear 50 comprises a first cylinder part 51 in which inner teeth are formed at an internal peripheral face, and a bottomed cylindrical second cylinder part 52 which is continuous to the first cylinder part 51. An external peripheral face of the second cylinder part 52 comprises a cylindrical plane shape fitting face 58 extending to an axial direction, and a pair of regulation faces 59 extending to the outside of a radial direction from one end part of the fitting face 58 in the axial direction and the other side end part in the axial direction. A first bearing 60 is arranged between an external peripheral face of the first cylinder part 51 and an internal peripheral face of a housing 10, and a second bearing 70 comprises a circular disc-shaped inner ring 71 which is arranged in a state of being fit to the fitting face 58 and arranged in a state of being sandwiched by the pair of regulation faces 59 in the axial direction, a circular disc-shaped outer ring 72 having an inside diameter larger than an outside diameter D1 of the first cylinder part 51, and rolling bodies 73 which roll between an external peripheral face of the inner ring 71 and an internal peripheral face of the outer ring 72.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a reduction gear.

  A reduction gear having a planetary gear mechanism is known. Patent Document 1 discloses a reduction gear in which a bottomed cylindrical movable internal gear having internal teeth meshing with a planetary gear is supported so as to be relatively rotatable with respect to a casing.

Japanese Utility Model Publication No. 63-185944

  However, in Patent Document 1 described above, when a radial load and an axial load generated in mesh with the planetary gear are applied to the movable internal gear, the cylindrical shape of the movable internal gear having the inner teeth formed on the inner peripheral surface. The portion is displaced in the radial direction and the axial direction. At this time, stress concentrates on the connection portion between the cylindrical portion and the bottom portion of the movable internal gear, and the occurrence of cracks or the like at the connection portion between the cylindrical portion and the bottom portion becomes a problem from the viewpoint of durability.

  An object of this invention is to provide the reduction gear which can improve durability of an internal gear by suppressing the concentration of stress.

  The speed reducer according to the present invention includes a cylindrical housing centered on the input / output axis, a sun gear that is an internal gear or an external gear centered on the input / output axis, and a planetary gear that meshes with the sun gear. A gear, a carrier that rotatably supports the planetary gear, an internal gear that is centered on the input / output axis and meshes with the planetary gear, and the internal gear that rotatably supports the housing A first bearing that receives a radial load, and a second bearing that rotatably supports the internal gear with respect to the housing and receives a radial load and an axial load. A first cylindrical portion having inner teeth formed on the inner peripheral surface, and a bottomed cylindrical shape having an opening on one side in the axial direction and a bottom portion on the other side in the axial direction. A second cylinder continuous to the other axial side of the cylindrical portion And an outer peripheral surface of the second cylindrical portion includes a cylindrical fitting surface extending in the axial direction, an end portion on the one axial side and an end portion on the other axial side of the fitting surface. A pair of regulating surfaces extending radially outward from the first bearing, the first bearing is disposed between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the housing, the second bearing, An annular inner ring arranged in a state of being fitted to the fitting surface and sandwiched between the pair of regulating surfaces in the axial direction, and larger than the outer diameter of the first cylindrical portion An annular outer ring having an inner diameter, and a rolling element that rolls between an outer peripheral surface of the inner ring and an inner peripheral surface of the outer ring.

  The speed reducer of the present invention includes a first bearing and a second bearing that support the internal gear so as to be relatively rotatable with respect to the housing. Since the first bearing is disposed between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the housing 10, the first bearing directly receives a radial load applied to the first cylindrical portion in accordance with the meshing with the planetary gear. be able to. Therefore, the displacement to the radial direction outer side of a 1st cylindrical part can be suppressed effectively.

  In addition, the outer peripheral surface of the second cylindrical portion that is continuous to the other axial side of the first cylindrical portion is a cylindrical surface-like fitting surface, and radially outward from one axial side and the other axial side of the fitting surface. And a pair of restricting surfaces extending inward. The inner ring of the second bearing is disposed on the fitting surface in a state sandwiched between the pair of regulating surfaces, and the outer ring of the second bearing has an outer diameter larger than the outer diameter of the first cylindrical portion. Therefore, the inner ring can be disposed at a position where the axial load applied to the first cylindrical portion can be efficiently received, and the axial load applied to the first cylindrical portion can be reliably received by the second bearing.

  Thus, in the speed reducer, the radial load and the axial load applied to the first cylindrical portion can be received by the first bearing and the second bearing. As a result, the displacement of the first cylindrical portion accompanying the meshing with the planetary gear can be restricted, and the stress concentration on the second cylindrical portion due to the displacement of the first cylindrical portion can be suppressed, so the second cylindrical portion is damaged early. As a result, the durability of the internal gear can be improved.

It is an axial sectional view of the speed reducer in the first embodiment of the present invention, and corresponds to a cross section taken along line II in FIG. 2A. It is sectional drawing of the speed reducer in the IIa-IIa line | wire of FIG. It is sectional drawing of the speed reducer in the IIb-IIb line | wire of FIG. It is the figure which expanded the axial direction sectional view of the reduction gear shown in FIG. 1 partially. It is the figure which expanded the axial direction cross section of the speed reducer in 2nd embodiment partially. It is an axial sectional view of the speed reducer in the third embodiment.

<First embodiment>
Hereinafter, an embodiment to which a reduction gear according to the present invention is applied will be described with reference to the drawings. First, with reference to FIG. 1 to FIG. 3, a reduction device 100 according to a first embodiment of the present invention will be described.

(1. Overall configuration of reduction gear device 100)
As shown in FIG. 1, the reduction gear 100 includes a housing 10, a sun gear 20 as a fixing member, a planetary gear 30, a carrier 40 as an input member, an internal gear 50 as an output member, A bearing 60, a second bearing 70, a third bearing 80, and a fourth bearing 90 are mainly provided.

  The housing 10 is a cylindrical member centered on the input / output axis A, and the first housing 11 disposed on the most axial direction (input / output axis A direction) one side (left side in FIG. 1) of the housing 10; A second housing 12 disposed on the other axial side of the first housing 11 (right side in FIG. 1), a third housing 13 disposed on the other axial side of the second housing 12, and an axial direction of the third housing 13 The fourth housing 14 is disposed on the other side, the most axially other side (the right side in FIG. 1) of the housing 10. The first housing 11, the second housing 12, the third housing 13, and the fourth housing 14 are all formed in a cylindrical shape, and are connected by bolts while being arranged coaxially. The sun gear 20 is an internal gear centered on the input / output axis A, and is fixed to the inner peripheral surface of the second housing 12 so as not to be relatively rotatable. The sun gear 20 is a helical gear.

  As shown in FIGS. 1, 2 </ b> A, and 2 </ b> B, the planetary gear 30 includes three first planetary gears 31 and three second planetary gears 32. The first planetary gear 31 is an external gear that meshes with the sun gear 20, and the three first planetary gears 31 are arranged around the input / output axis A at equal intervals in the circumferential direction. The second planetary gear 32 is an external gear having fewer teeth than the first planetary gear 31 and meshes with the internal gear 50. The three second planetary gears 32 are arranged at equal intervals in the circumferential direction around the input / output axis A, and each second planetary gear 32 is arranged coaxially with each first planetary gear 31. The first planetary gear 31 and the second planetary gear 32 are both helical gears. The first planetary gear 31 includes a first insertion hole 31a and a first recess 31b, and the second planetary gear 32 includes a second insertion hole 32a and a second recess 32b.

  The first insertion hole 31 a is a substantially regular hexagonal hole as viewed in the axial direction and is formed through the central portion of the first planetary gear 31 in the axial direction. The second insertion hole 32a is a substantially regular hexagonal hole as viewed in the axial direction and is formed in the central portion of the second planetary gear 32 in the axial direction. The shape of the second insertion hole 32a viewed from the axial direction is It is equivalent to one insertion hole 31a. The first concave portion 31b is a circular hole viewed in the axial direction on the side surface of the first planetary gear 31 facing the one side in the axial direction (left side in FIG. 1) and recessed toward the other side in the axial direction (right side in FIG. 1). Yes, formed at the peripheral edge of the first insertion hole 31a. The second recess 32b is a circular hole viewed in the axial direction that is recessed toward the one side in the axial direction (left side in FIG. 1) on the side surface facing the other side in the axial direction (right side in FIG. 1) of the second planetary gear 32. Yes, formed at the peripheral edge of the second insertion hole 32a.

  The carrier 40 rotatably supports the three first planetary gears 31 and the three second planetary gears 32. The carrier 40 includes a pair of carrier support members 41, three carrier shaft members 42, and three restriction members 43. In the present embodiment, the three carrier shaft members 42 are rotatable with respect to the pair of carrier support members 41. However, like the speed reducer 300 of the third embodiment described later, the three carrier shaft members 42 The 342 may be fixed to the pair of carrier support members 341 so as not to rotate (see FIG. 5).

  The pair of carrier support members 41 includes a first support member 41 a and a second support member 41 b that are disposed opposite to each other in the axial direction across the first planetary gear 31 and the second planetary gear 32. The first support member 41 a is a member disposed on one side in the axial direction of the pair of carrier support members 41, and is supported relative to the housing 10 via the third bearing 80. The second support member 41 b is a member disposed on the other side in the axial direction of the pair of carrier support members 41, and is supported by the internal gear 50 via the fourth bearing 90 so as to be relatively rotatable. The first support member 41a and the second support member 41b are fixed by bolts, and displacement in a direction approaching or separating from each other is restricted.

  The carrier shaft member 42 includes a prismatic portion 42a and a pair of cylindrical portions 42b. The rectangular column part 42 a is a part that is inserted into the first insertion hole 31 a of the first planetary gear 31 and the second insertion hole 32 a of the second planetary gear 32. The prismatic part 42a is formed in a substantially polygonal columnar shape, and the outer shape of the prismatic part 42a viewed from the axial direction is partly cut out of a substantially regular hexagonal outer shape following the first insertion hole 31a and the second insertion hole 32a. It has an almost hexagonal shape. The pair of cylindrical portions 42b are cylindrical portions that are rotatably supported by the pair of carrier support members 41 via needle bearings 42c, and extend in the axial direction from both axial ends of the prismatic portion 42a.

  The regulating member 43 includes a pair of locking portions 43a and a connecting portion 43b. The pair of locking portions 43a are arranged to face each other, and the facing interval between the pair of locking portions 43a is a length obtained by combining the axial length of the first insertion hole 31a and the axial length of the second insertion hole 32a. It is equivalent to the size. The connecting portion 43b is a portion formed in a rectangular plate shape, and a pair of locking portions 43a are connected to both ends in the longitudinal direction of the connecting portion 43b.

  In a state where the prismatic part 42a is inserted into the first insertion hole 31a and the second insertion hole 32a, the relative rotation of the prismatic part 42a with respect to the first insertion hole 31a and the second insertion hole 32a is restricted, and the connecting part 43b The first insertion hole 31a and the second insertion hole 32a are inserted into a gap formed by the prism portion 42a in a state where relative rotation is impossible. Thereby, the first planetary gear 31 and the second planetary gear 32 are fixed to the carrier shaft member 42 so as to be integrally rotatable.

  The first planetary gear 31 and the second planetary gear 32 are disposed between the pair of locking portions 43a in a state where the connecting portion 43b and the prismatic portion 42a are inserted into the first insertion hole 31a and the second insertion hole 32a. Thus, the displacement of the first planetary gear 31 and the second planetary gear 32 in the direction away from each other is restricted.

  As shown in FIG. 1, the internal gear 50 is an internal gear centered on the input / output axis A and rotates relative to the housing 10. The first bearing 60 and the second bearing 70 are bearings that support the internal gear 50 so as to be rotatable relative to the housing 10. The detailed configuration of the internal gear 50, the first bearing 60, and the second bearing 70 will be described in detail with reference to FIG.

  The third bearing 80 is a deep groove ball bearing that supports the carrier 40 so as to be rotatable relative to the housing 10, and includes an outer peripheral surface of the first support member 41 a and inner peripheral surfaces of the first housing 11 and the second housing 12. Are disposed in a state where displacement in the axial direction is restricted. The fourth bearing 90 is a deep groove ball bearing that supports the carrier 40 so as to be relatively rotatable with respect to the internal gear 50, and a shaft between the outer peripheral surface of the second support member 41b and a second cylindrical portion 52 described later. It is arranged in a state where displacement in the direction is restricted.

(2. Configuration of the internal gear 50)
Next, the internal gear 50 will be described with reference to FIG. As shown in FIG. 3, the internal gear 50 includes a first cylindrical portion 51 and a second cylindrical portion 52. The first cylindrical portion 51 is a portion formed in a cylindrical shape, and an inner tooth that meshes with the second planetary gear 32 is formed on the inner peripheral surface. The second cylindrical portion 52 is a bottomed cylindrical member having an opening on one side in the axial direction (left side in FIG. 3) and a bottom 53 formed on the other side in the axial direction (right side in FIG. 3). One end in the axial direction of the first cylindrical portion 51 is formed continuously with the other end in the axial direction of the first cylindrical portion 51.

  The inner peripheral surface of the second cylindrical portion 52 includes a first inner peripheral surface 54, an annular surface 55, and a second inner peripheral surface 56. The first inner peripheral surface 54 is a cylindrical inner peripheral surface portion extending to the other side in the axial direction. The first inner peripheral surface 54 is located on the most axial side of the inner peripheral surface of the second cylindrical portion 52, and is formed continuously with the inner peripheral surface of the first cylindrical portion 51. The annular surface 55 is a surface perpendicular to the axial direction of the second cylindrical portion 52, is continuous with the other axial end of the first inner peripheral surface 54, and extends radially inward. The second inner peripheral surface 56 is a cylindrical inner peripheral surface portion continuous to the radially inner end of the annular surface 55 and the bottom 53, and the inner diameter of the second inner peripheral surface 56 is the first inner peripheral surface. It is smaller than the inner diameter of 54.

  In addition, by forming the second cylindrical portion 52 between the first cylindrical portion 51 and the bottom portion 53, the second cylindrical portion 52 is formed on the inner peripheral surface of the first cylindrical portion 51 on the inner peripheral surface side. A gap is formed between the second planetary gear 32 that meshes with the inner teeth and the bottom 53. In the reduction gear 100, since the second support member 41b is disposed in the gap formed between the second planetary gear 32 and the bottom 53, the axial length of the reduction gear 100 can be reduced.

  The outer peripheral surface of the second cylindrical portion 52 includes a cylindrical outer peripheral surface 57, a fitting surface 58, and a pair of restricting surfaces 59. The cylindrical outer peripheral surface 57 is a cylindrical surface-like portion extending in the axial direction, and is located on the most axial side of the outer peripheral surface of the second cylindrical portion 52. The outer diameter of the cylindrical outer peripheral surface 57 is equal to the outer diameter D1 of the first cylindrical portion 51, and the cylindrical outer peripheral surface 57 and the first cylindrical portion 51 are continuously formed in a flush manner. The fitting surface 58 is a cylindrical surface-like portion disposed on the other axial side of the cylindrical outer peripheral surface 57, and the outer diameter D <b> 2 of the fitting surface 58 is smaller than the outer diameter of the cylindrical outer peripheral surface 57. It is larger than the inner diameter of the inner peripheral surface 54 and the second inner peripheral surface 56.

  The pair of restricting surfaces 59 are annular surface-shaped portions extending radially outward from the end portion on the one axial side and the other end portion on the other axial side of the fitting surface 58, and the shaft of the second cylindrical portion 52. A plane perpendicular to the direction. Of the pair of restricting surfaces 59, the first restricting surface 59a disposed on one side in the axial direction includes an end on the other side in the axial direction of the cylindrical outer peripheral surface 57 and an end on the one side in the axial direction of the fitting surface 58. Connecting.

  Of the pair of regulating surfaces 59, the second regulating surface 59b disposed on the other axial side is separate from the bottomed cylindrical member 52A that forms the cylindrical outer circumferential surface 57, the first regulating surface 59a, and the fitting surface 58. And is formed by an annular plate-like member 52B having an outer diameter larger than the outer diameter D2 of the fitting surface 58. That is, the second cylindrical portion 52 is a bottomed cylindrical member in a state where the surface facing the one axial direction of the annular plate member 52B is aligned with the surface facing the other axial direction of the bottomed cylindrical member 52A. 52A and the annular plate-like member 52B are connected by bolts, and the other of the surfaces of the annular plate-like member 52B facing the one side in the axial direction is the other in the axial direction of the bottomed cylindrical member 52A. A portion projecting outward in the radial direction from the surface facing the side forms the second regulating surface 59b.

(3. Configuration of the first bearing 60 and the second bearing 70)
Next, the first bearing 60 will be described. The first bearing 60 is a needle bearing that receives a radial load applied to the internal gear 50 while supporting the internal gear 50 so as to be relatively rotatable with respect to the housing 10. The first bearing 60 is disposed between the outer peripheral surface of the first cylindrical portion 51 and a part of the cylindrical outer peripheral surface 57 and the inner peripheral surface of the second housing 12. Further, the first bearing 60 is disposed in a state where both axial sides are sandwiched between the second housing 12 and the third housing 13, thereby restricting relative displacement in the axial direction of the first bearing 60 with respect to the housing 10. The

  Here, when the internal gear 50 meshes with the second planetary gear 32, a radial load is applied to the internal gear 50 along with the meshing with the second planetary gear 32, and the internal teeth are formed on the inner peripheral surface. A force is generated to displace the first cylindrical portion 51 radially outward. When the first cylindrical portion 51 is displaced radially outward, stress concentrates on a portion where the strength of the second cylindrical portion 52 is weak (for example, a bent portion where the first inner peripheral surface 54 and the annular surface 55 are connected). In addition, cracks and the like may occur at an early stage.

  On the other hand, in the reduction gear 100, the first bearing 60 is disposed between the outer peripheral surface of the first cylindrical portion 51 and the second housing 12. Thereby, the radial load applied to the first cylindrical portion 51 can be directly received by the first bearing 60 disposed on the radially outer side of the first cylindrical portion 51. Can be effectively suppressed.

  Next, the second bearing 70 will be described. The second bearing 70 is a deep groove ball bearing that receives an axial load and a radial load applied to the internal gear 50 while supporting the internal gear 50 so as to be relatively rotatable with respect to the housing 10. 72 and rolling elements 73.

  The inner ring 71 is an annular member arranged in a state of being fitted to the fitting surface 58 of the second cylindrical portion 52. The inner ring 71 is disposed in a state where both sides in the axial direction are sandwiched between the pair of restriction surfaces 59, thereby restricting relative displacement in the axial direction with respect to the internal gear 50. The outer ring 72 is an annular member having an inner diameter larger than the outer diameter of the inner ring 71. The outer ring 72 is disposed in a state where both sides in the axial direction are sandwiched between the third housing 13 and the fourth housing 14, so that displacement in the axial direction with respect to the housing 10 is restricted. The rolling element 73 is a ball that rolls between the outer peripheral surface of the inner ring 71 of the second bearing 70 and the inner peripheral surface of the outer ring 72 of the second bearing 70.

  Here, the second planetary gear 32 and the internal gear 50 are helical gears. Therefore, an axial load is generated in the internal gear 50 along with the meshing with the second planetary gear 32, and the first cylindrical portion 51 having the internal teeth formed on the inner peripheral surface is displaced in the axial direction. To generate power. When the first cylindrical portion 51 is displaced in the axial direction, stress concentrates on a portion where the strength of the second cylindrical portion 52 is weak, and there is a possibility that a crack or the like may occur. Further, even when an axial load caused by an external force is applied to the internal gear 50, there is a possibility that a crack or the like may occur in the second cylindrical portion 52.

  On the other hand, in the reduction gear 100, the inner ring 71 of the second bearing 70 is restricted from displacement in the axial direction by the pair of restriction surfaces 59, and the outer ring 72 is moved in the axial direction by the third housing 13 and the fourth housing 14. Displacement is regulated. Thereby, the axial load applied to the first cylindrical portion 51 can be received by the second bearing 70. Further, the second bearing 70 constituted by the deep groove ball bearing can receive a radial load applied to the internal gear 50, and the radial load applied to the internal gear 50 is applied to the first bearing 60 and the second bearing 70. Can be received by both sides.

  Thus, the reduction gear 100 can receive the radial load and the axial load applied to the first cylindrical portion 51 by the first bearing 60 and the second bearing 70. Thereby, the displacement of the 1st cylindrical part 51 accompanying mesh | engagement with the 2nd planetary gear 32 is controlled, and the stress concentration to the 2nd cylindrical part resulting from the displacement of a 1st cylindrical part can be suppressed. Therefore, the second cylindrical portion 52 can be prevented from being damaged early, and as a result, the durability of the internal gear 50 can be improved.

  A retaining ring has heretofore been widely used as a member for regulating the axial displacement of the deep groove ball bearing. However, the conventional retaining ring is not designed to receive an axial load, and the axial retaining load applied to the first cylindrical portion 51 as a result of meshing with the second planetary gear 32 is reduced. It is difficult to receive only by. Temporarily, in this embodiment, when the 2nd control surface 59b is formed with the conventional retaining ring, there exists a possibility that malfunctions, such as a retaining ring coming off by the axial load which the inner ring 71 received, may generate | occur | produce.

  On the other hand, in the present embodiment, the second restricting surface 59b is formed by the annular plate-like member 52B connected to the bottomed tubular member 52A with a bolt. As a result, the axial load applied to the first cylindrical portion 51 can be received by the second bearing 70.

  Further, in the reduction gear 100, a needle bearing is used as the first bearing 60 that receives the radial load, and a deep groove ball bearing is used as the second bearing 70 that receives the radial load and the axial load. Therefore, for example, compared with the case where the radial load and the axial load applied to the internal gear 50 are received by the cross roller bearing, the component cost can be suppressed.

(4. Dimensions of the internal gear 50, the first bearing 60, and the second bearing 70)
With respect to the inner peripheral surface of the internal gear 50, the inner diameter of the second inner peripheral surface 56 is set to be smaller than the inner diameter of the first inner peripheral surface 54, and the annular surface 55 is one axial direction than the first regulating surface 59a. Located on the side (left side of FIG. 3). That is, the inner peripheral surface shape of the bottomed cylindrical member 52 </ b> A of the second cylindrical portion 52 is formed following the outer peripheral surface shape of the bottomed cylindrical member 52 </ b> A of the second cylindrical portion 52. Thereby, the thickness of the 2nd cylindrical part 52 can be set to an appropriate dimension, aiming at weight reduction of the 2nd cylindrical part 52. FIG.

  Further, regarding the outer peripheral surface of the internal gear 50, the outer diameter of the cylindrical outer peripheral surface 57 is equal to the outer diameter D1 of the first cylindrical portion 51. The maximum outer diameter of the internal gear 50 can be reduced as compared with a case where the inner gear 50 is set larger. Further, the outer diameter D2 of the fitting surface 58 is made smaller than the outer diameter D1 of the first cylindrical portion 51 by setting the outer diameter of the cylindrical outer peripheral surface 57 to the same size as the outer diameter D1 of the first cylindrical portion 51. can do. Thereby, since the internal diameter of the inner ring 71 of the second bearing 70 fitted to the fitting surface 58 can be reduced, the size of the second bearing 70 can be reduced.

  In addition, by setting the outer diameter of the cylindrical outer peripheral surface 57 to a dimension equivalent to the outer diameter D1 of the first cylindrical portion 51, the outer peripheral surface of the first cylindrical portion 51 and the cylindrical outer peripheral surface 57 are formed flush with each other. be able to. That is, the stress is easily concentrated when a radial load and an axial load are applied to the portion that bends to the connection portion between the outer peripheral surface of the first cylindrical portion 51 and the cylindrical outer peripheral surface 57, that is, the first cylindrical portion 51. Since the formation of the portion can be avoided, the durability of the internal gear 50 can be improved.

  In the reduction gear 100, a needle bearing is used as the first bearing 60 that receives the radial load, and the outer diameter D4 of the first bearing 60 is set to be smaller than the outer diameter D5 of the outer ring 72 of the second bearing 70. . Thereby, the radial direction dimension of the reduction gear 100 can be made small in the site | part in which the 1st bearing 60 is arrange | positioned.

  When a needle bearing is used as the first bearing 60, the axial load applied to the first cylindrical portion 51 cannot be sufficiently received, and the axial direction of the first cylindrical portion 51 due to the axial load is not received. It is difficult to restrict the displacement by the first bearing 60. In this regard, in the reduction gear 100, the second bearing 70 having the inner ring 71 and the outer ring 72 is disposed on the other axial side of the first cylindrical portion 51, and the axial load applied to the first cylindrical portion 51 by the second bearing 70. Receive. Thereby, the displacement to the axial direction of the 1st cylindrical part 51 is controlled, and it can suppress that stress concentrates on the site | part with a weak intensity | strength of the 2nd cylindrical part 52. FIG.

  On the other hand, the second bearing 70 having the inner ring 71 and the outer ring 72 has a larger width dimension in the radial direction than the first bearing 60 which is a needle bearing. On the other hand, the speed reducer 100 reduces the size of the second bearing 70 by making the outer diameter D2 of the fitting surface 58 to which the inner ring 71 is fitted smaller than the outer diameter D1 of the first cylindrical portion 51. be able to. As a result, the radial dimension of the reduction gear 100 can be reduced even at the portion where the second bearing 70 is disposed.

  Further, in the relationship between the second bearing 70 and the outer peripheral surface of the first cylindrical portion 51, the outer diameter D2 of the fitting surface 58 to which the inner diameter of the inner ring 71 is fitted is larger than the outer diameter D1 of the first cylindrical portion 51. A small dimension is set, and the inner diameter D3 of the outer ring 72 is set to be larger than the outer diameter D1 of the first cylindrical portion 51. Accordingly, the inner ring 71 can be disposed at a position where the axial load applied to the first cylindrical portion 51 can be efficiently received, that is, at a position overlapping the first cylindrical portion 51 when viewed from the axial direction. The axial load applied to the cylindrical portion 51 can be reliably received by the second bearing 70.

  In this embodiment, the outer diameter of the inner ring 71 of the second bearing 70 is set to be larger than the outer diameter of the cylindrical outer peripheral surface 57, but the outer diameter of the inner ring 71 of the second bearing 70 is cylindrical. It may be smaller than the outer diameter of the outer peripheral surface 57, and may be equal to the outer diameter of the cylindrical outer peripheral surface 57.

<Second embodiment>
Next, a second embodiment will be described with reference to FIG. In the first embodiment, the inner peripheral surface of the second cylindrical portion 52 includes a first inner peripheral surface 54 and a second inner peripheral surface 56 having an inner diameter smaller than the inner diameter of the first inner peripheral surface 54. In the second embodiment, the inner peripheral surface 256 of the second cylindrical portion 252 is constant in the axial direction. The speed reduction device 200 in the second embodiment has the same configuration as the speed reduction device 100 in the first embodiment except for the shape of the inner peripheral surface of the second cylindrical portion 252.

(5. Inner peripheral surface 256 of the second cylindrical portion 252)
As shown in FIG. 4, the inner peripheral surface 256 of the second cylindrical portion 252 (bottomed tubular member 252A) is formed in a cylindrical inner peripheral surface extending in the axial direction, and the inner peripheral surface 256 of the second cylindrical portion 252. One side in the axial direction (left side in FIG. 4) continues to the inner peripheral surface of the first cylindrical portion 51, and the other side in the axial direction of the inner peripheral surface 256 (right side in FIG. 4) continues to the bottom portion 53. .

  In this case, it is possible to avoid the formation of a bent portion on the inner peripheral surface 256 of the second cylindrical portion 252, that is, a portion where stress is concentrated. Therefore, the durability of the internal gear 250 can be improved.

<Third embodiment>
Next, a third embodiment will be described with reference to FIG. In the first embodiment, the speed reducer 100 using the carrier 40 as an input member has been described. In the third embodiment, the speed reducer 200 using the first sun gear 321 as an external member that meshes with the planetary gear 230 as an input member. Will be described. In addition, the same code | symbol is attached | subjected to the components same as each above-mentioned embodiment, and the description is abbreviate | omitted.

(6. Configuration of the reduction gear 300)
As shown in FIG. 5, the speed reduction device 300 includes a housing 10, a first sun gear 321 as an input member, a second sun gear 322, a planetary gear 330, a carrier 340, and an internal gear as an output member. 50, a first bearing 60, a second bearing 70, a third bearing 80, and a fourth bearing 90 are mainly provided.

  The first sun gear 321 is an external gear centered on the input / output axis A and is supported so as to be rotatable relative to the carrier 340. The second sun gear 322 is an internal gear centered on the input / output axis A, and is fixed to the second housing 12 so as not to rotate. The planetary gear 330 includes three first planetary gears 331 arranged at equal circumferential intervals around the input / output axis A, and three second planetary gears 332 arranged coaxially with the three first planetary gears 331. The first planetary gear 331 and the second planetary gear 332 that are coaxially arranged are connected via a fixing pin 330a so as to be integrally rotatable.

  The first planetary gear 331 is an external gear that meshes with the first sun gear 321 and the second sun gear 322, and includes a first insertion hole 331a. The second planetary gear 332 is an external gear that meshes with the internal gear 50 and includes a second insertion hole 332a. The first insertion hole 331a and the second insertion hole 332a are circular holes as viewed in the axial direction that are formed through the central portion of the first planetary gear 331 or the second planetary gear 332 in the axial direction.

  The carrier 340 includes a pair of carrier support members 341 and three carrier shaft members 342. The pair of carrier support members 341 includes a first support member 341a and a second support member 341b that are disposed opposite to each other on both sides in the axial direction with the first planetary gear 331 and the second planetary gear 332 interposed therebetween. The first support member 341 a is a member disposed on one axial side of the pair of carrier support members 341, and is supported relative to the housing 10 via a third bearing 80. The second support member 341 b is a member disposed on the other axial side of the pair of carrier support members 341, and is supported relative to the internal gear 50 via the fourth bearing 90 so as to be relatively rotatable.

  A pair of fifth bearings 341c, which are deep groove ball bearings, are provided between the inner peripheral surfaces of the first support member 341a and the second support member 341b and the outer peripheral surface of the first sun gear 321. The pair of carrier support members 341 supports the first sun gear 321 through the 341c so as to be rotatable.

  The carrier shaft member 342 is a cylindrical member having an outer diameter smaller than the inner diameters of the first insertion hole 331a of the first planetary gear 331 and the second insertion hole 332a of the second planetary gear 332. The carrier shaft member 342 is inserted into the first insertion hole 331a and the second insertion hole 332a, and the first planetary gear 331 and the second planetary gear 332 are rotatably supported by the carrier shaft member 342 via the needle bearing 342c. The Further, both ends in the axial direction of the carrier shaft member 342 are fixed to a pair of carrier support members 341 disposed on both sides in the axial direction with the planetary gear 330 interposed therebetween.

  Also in the reduction gear 300 described above, the radial load and the axial load applied to the internal gear 50 can be received by the first bearing 60 and the second bearing 70. Thereby, the displacement of the first cylindrical part 51 accompanying the meshing with the second planetary gear 332 is restricted, and the stress concentration on the second cylindrical part 52 due to the displacement of the first cylindrical part 51 can be suppressed. Therefore, the second cylindrical portion 52 can be prevented from being damaged early, and as a result, the durability of the internal gear 50 can be improved.

(7. Others)
Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. It can be easily guessed.

  For example, in each of the above-described embodiments, the case where a needle bearing is used as the first bearing 60 has been described, but another bearing capable of receiving a radial load may be used instead of the needle bearing. In each of the above embodiments, the case where a deep groove ball bearing is used as the second bearing 70 has been described. However, instead of the deep groove ball bearing, a bearing including an inner ring, an outer ring, and a rolling element, the radial load Other bearings capable of receiving both the load and the axial load may be used.

  In each of the above embodiments, the case where the outer diameter of the cylindrical outer peripheral surface 57 is equal to the outer diameter D1 of the first cylindrical portion 51 has been described. It may be different from the outer diameter D1. For example, the outer diameter of the cylindrical outer peripheral surface 57 may be larger than the outer diameter D 1 of the first cylindrical portion 51, and as a result, the outer diameter D 2 of the fitting surface 58 is outside the first cylindrical portion 51. The dimension may be larger than the diameter D1.

  In each of the above-described embodiments, the case where the second cylindrical portions 52 and 252 are formed by connecting the bottomed cylindrical members 52A and 252A and the annular plate-shaped member 52B with bolts has been described. 52 and 252 may be formed of one member. Further, in each of the above-described embodiments, the outer diameter of the annular plate member 52B is set to be larger than the outer diameter D2 of the fitting surface 58, and the annular plate member 52B is made of bottomed cylindrical members 52A and 252A. In the state of being connected to the ring plate-like member 52B, the portion that protrudes radially outward from the fitting surface 58 is described as the second restricting surface 59b, but by a member other than the annular plate-like member 52B. The second restriction surface 59b may be formed. For example, instead of the annular plate-like member 52B, an annular member capable of regulating the displacement in the axial direction of the first cylindrical portion 51 by receiving an axial load applied to the first cylindrical portion 51 is fitted. It may be attached to the mating surface 58.

  In each of the above embodiments, the case where the planetary gears 30 and 330 are configured by two external gears (first planetary gears 31 and 331 and second planetary gears 32 and 332) having different numbers of teeth has been described. There may be one.

  In the first embodiment described above, the case where the sun gear 20 meshed with the first planetary gear 31 is an internal gear fixed to the second housing 12 has been described. However, the external gear meshed with the first planetary gear 31 is used. The sun gear 20 may be used. In this case, the sun gear 20 that is an external gear may be fixed and the carrier 40 may be used as an input member in the planetary gear mechanism, or the carrier 40 may be fixed and the sun gear 20 that is an external gear may be used as the input member in the planetary gear mechanism. . In the first embodiment described above, the case where the sun gear 20 is a fixing member and the internal gear 50 is an output member in the planetary gear mechanism has been described. For example, the internal gear 50 is an input member in the planetary gear mechanism. The sun gear 20 may be an output member in the planetary gear mechanism.

  In each embodiment described above, the first planetary gears 31 and 331 and the second planetary gears 32 and 332 are helical gears, and the sun meshes with the first planetary gears 31 and 331 or the second planetary gears 32 and 332. Although the case where the gear 20, the first sun gear 321, the second sun gear 322, and the internal gears 50 and 250 are helical gears has been described, it may not be a helical gear. Even if it is not a helical gear, when an axial load caused by an external force is applied to the internal gears 50 and 250, the axial load can be received by the second bearing 70. The durability of 50 and 250 can be improved.

(8. Effect)
As described above, the reduction gears 100, 200, and 300 are the cylindrical housing 10 centered on the input / output axis A and the sun gear 20 or the external gear that is the internal gear centered on the input / output axis A. One sun gear 321, planetary gears 30 and 330 that are external gears meshed with the sun gear 20 that is an internal gear or the first sun gear 321 that is an external gear, and a carrier 40 that rotatably supports the planetary gears 30 and 330. , 340, the internal gears 50, 250 centered on the input / output axis A and meshing with the planetary gears 30, 330, and the internal gears 50, 250 are rotatably supported with respect to the housing 10, and the radial direction A first bearing 60 that receives a load, and a second bearing 70 that rotatably supports an internal gear 50.250 with respect to the housing 10 and that receives a radial load and an axial load.

  In addition, the internal gears 50 and 250 include a first cylindrical portion 51 having internal teeth formed on the inner peripheral surface, a bottomed tube having an opening on one side in the axial direction and a bottom 53 on the other side in the axial direction. Second cylindrical portions 52 and 252 that are formed in a shape and have one axial side continuous with the other axial side of the first cylindrical portion 51, and the outer peripheral surfaces of the second cylindrical portions 52 and 252 extend in the axial direction. A cylindrical surface-like fitting surface 58 and a pair of restricting surfaces 59 extending radially outward from one end in the axial direction and the other end in the axial direction of the fitting surface 58 are provided. In addition, the first bearing 60 is disposed between the outer peripheral surface of the first cylindrical portion 51 and the inner peripheral surface of the housing 10, and the second bearing 70 is disposed in a state of being fitted to the fitting surface 58. And an annular inner ring 71 disposed between the pair of regulating surfaces 59 in the axial direction, and an annular outer ring 72 having an inner diameter larger than the outer diameter D1 of the first cylindrical portion 51, A rolling element 73 that rolls between the outer peripheral surface of the inner ring 71 and the inner peripheral surface of the outer ring 72.

  According to the reduction gears 100, 200, and 300, the reduction gears 100, 200, and 300 include the first bearing and the second bearing that support the internal gears 50 and 250 so as to be relatively rotatable with respect to the housing 10. Since the first bearing 60 is disposed between the outer peripheral surface of the first cylindrical portion 51 and the inner peripheral surface of the housing 10, the radial direction applied to the first cylindrical portion 51 along with the meshing with the planetary gears 30 and 330. The load can be directly received. Therefore, the displacement to the radial direction outer side of the 1st cylindrical part 51 can be suppressed effectively.

  In addition, the outer peripheral surfaces of the second cylindrical portions 52 and 252 that are continuous to the other axial side of the first cylindrical portion 51 are a cylindrical fitting surface 58, one axial side of the fitting surface 58, and the other axial direction. And a pair of regulating surfaces 59 extending radially outward from the side. The inner ring 71 of the second bearing 70 is disposed on the fitting surface 58 while being sandwiched between the pair of regulating surfaces 59, and the inner diameter D <b> 3 of the outer ring 72 of the second bearing 70 is larger than the outer diameter D <b> 1 of the first cylindrical portion 51. Is also big. Therefore, the inner ring 71 can be disposed at a position where the axial load applied to the first cylindrical portion 51 can be efficiently received, and the axial load applied to the first cylindrical portion 51 can be reliably received by the second bearing 70. .

  As described above, the reduction gears 100, 200, and 300 can receive the radial load and the axial load applied to the first cylindrical portion 51 by the first bearing 60 and the second bearing 70. Thereby, the displacement of the 1st cylindrical part 51 accompanying mesh | engagement with the planetary gears 30 and 330 is controlled, and the stress concentration to the 2nd cylindrical parts 52 and 252 resulting from the displacement of the 1st cylindrical part 51 can be suppressed. Therefore, the second cylindrical portions 52 and 252 can be prevented from being damaged early, and as a result, the durability of the internal gears 50 and 250 can be improved.

  In the reduction gears 100, 200, and 300, the outer diameter D1 of the first cylindrical portion 51 is larger than the outer diameter D2 of the fitting surface 58, and the outer diameter D4 of the first bearing 60 is the outer ring of the second bearing 70. 72 or less of the outer diameter D5. In this case, since the radial dimension can be reduced at the portion where the first bearing 60 is disposed, the reduction gears 100, 200, 300 can be reduced in size.

  In the reduction gears 100 and 300, the inner peripheral surface of the second cylindrical portion 52 is continuous with the inner peripheral surface on the other axial side of the first cylindrical portion 51, and extends to the other axial side. And an annular surface 55 extending radially inward, continuous to the radially inner end and bottom 53 of the annular surface 55, and continuing to the other axial end of the first inner peripheral surface 54, A second inner peripheral surface 56 extending to the other side in the direction, and the annular surface 55 is disposed on the one side in the axial direction from the pair of regulating surfaces 59.

  According to the reduction gears 100 and 300, since the inner peripheral surface of the second cylindrical portion 52 is formed in a shape that follows the outer peripheral surface of the second cylindrical portion 52, while reducing the weight of the second cylindrical portion 52, The thickness of the second cylindrical portion 52 can be set to an appropriate dimension.

  Further, in the reduction gear 200, the inner diameter of the second cylindrical portion 252 is the same in the entire axial direction. In this case, it is possible to avoid the formation of a portion where stress tends to concentrate on the inner peripheral surface 256 of the second cylindrical portion 252. Therefore, the durability of the internal gear 250 can be improved.

  In the reduction gears 100, 200, and 300, the planetary gears 30 and 330 are the first planetary gears 31 and 331 that mesh with the sun gear 20 that is an internal gear or the first sun gear 321 that is an external gear, and an internal gear. The second planetary gears 32 and 332 meshing with the first planetary gears 32 and 332, and the carriers 40 and 340 are arranged on one side in the axial direction with respect to the first planetary gears 31 and 331 and the second planetary gears 32 and 332, and First support members 41a and 341a that rotatably support the planetary gears 31 and 331 and the second planetary gears 32 and 332, and the other side in the axial direction with respect to the first planetary gears 31 and 331 and the second planetary gears 32 and 332 And second support members 41b and 341b that rotatably support the first planetary gears 31 and 331 and the second planetary gears 32 and 332, and the second support members 41b and 341b A inner peripheral surface of the cylindrical portion 52, 252 is disposed between the second planetary gear 32,332 and the bottom 53. According to the reduction gears 100, 200, and 300, the axial length of the reduction gears 100, 200, and 300 can be reduced.

  10: Housing, 20: Sun gear, 30, 330: Planetary gear, 31, 331: First planetary gear, 32, 332: Second planetary gear, 40, 340: Carrier, 41a, 341a: First support member, 41b , 341b: second support member, 50, 250: internal gear, 51: first cylindrical portion, 52, 252: second cylindrical portion, 53: bottom portion, 54: first inner peripheral surface, 55: annular surface, 56: second inner peripheral surface, 58: fitting surface, 59: restriction surface, 60: first bearing, 70: second bearing, 71: inner ring, 72: outer ring, 73: rolling element, 100, 200, 300: Reduction device, 256: inner peripheral surface (of second cylindrical portion): 321: first sun gear (sun gear), D1: outer diameter of first cylindrical portion, D2: outer diameter of fitting surface, D3: outer ring Inner diameter, D4: outer diameter of the first bearing, D5: outer diameter of the outer ring

Claims (5)

A cylindrical housing around the input / output axis;
A sun gear that is an internal gear or an external gear centered on the input / output axis;
A planetary gear which is an external gear meshing with the sun gear;
A carrier rotatably supporting the planetary gear;
An internal gear centered on the input / output axis and meshing with the planetary gear;
A first bearing that rotatably supports the internal gear with respect to the housing and receives a radial load;
A second bearing that rotatably supports the internal gear with respect to the housing and receives a radial load and an axial load;
With
The internal gear is
A first cylindrical portion having inner teeth formed on the inner peripheral surface;
A second cylindrical portion that is open on one side in the axial direction and is formed in a bottomed cylindrical shape having a bottom on the other side in the axial direction, and the one axial direction continues to the other side in the axial direction of the first cylindrical portion;
With
The outer peripheral surface of the second cylindrical portion is
A cylindrical mating surface extending in the axial direction;
A pair of regulating surfaces extending radially outward from the one axial side and the other axial side of the fitting surface;
With
The first bearing is disposed between an outer peripheral surface of the first cylindrical portion and an inner peripheral surface of the housing,
The second bearing is
An annular inner ring that is arranged in a state of being fitted to the fitting surface, and is arranged in a state of being sandwiched between the pair of regulating surfaces in the axial direction;
An annular outer ring having an inner diameter larger than the outer diameter of the first cylindrical portion;
A rolling element that rolls between an outer peripheral surface of the inner ring and an inner peripheral surface of the outer ring;
A speed reducer comprising: The outer diameter of the first cylindrical portion is larger than the outer diameter of the fitting surface,
The reduction gear according to claim 1, wherein an outer diameter of the first bearing is equal to or less than an outer diameter of the outer ring of the second bearing. The inner peripheral surface of the second cylindrical portion is
A first inner peripheral surface continuous to an inner peripheral surface on the other axial side of the first cylindrical portion and extending to the other axial side;
An annular surface that is continuous with the end portion on the other side in the axial direction of the first inner peripheral surface and extends radially inward;
A second inner peripheral surface extending to the radially inner end of the annular surface and the bottom and extending to the other side in the axial direction;
With
The speed reduction device according to claim 1 or 2, wherein the annular surface is disposed on one axial side of the pair of regulating surfaces.   The reduction gear according to claim 1 or 2, wherein the inner diameter of the second cylindrical portion is the same in the entire axial direction. The planetary gear includes a first planetary gear that meshes with the sun gear, and a second planetary gear that meshes with the internal gear,
The carrier is
A first support member disposed on one side in the axial direction with respect to the first planetary gear and the second planetary gear, and rotatably supporting the first planetary gear and the second planetary gear;
A second support member disposed on the other side in the axial direction with respect to the first planetary gear and the second planetary gear, and rotatably supporting the first planetary gear and the second planetary gear;
With
5. The second support member according to claim 1, wherein the second support member is disposed on an inner peripheral surface side of the second cylindrical portion and between the second planetary gear and the bottom portion. Reducer.

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