WO2015111326A1

WO2015111326A1 - Gear power transmission device

Info

Publication number: WO2015111326A1
Application number: PCT/JP2014/083168
Authority: WO
Inventors: 真哉廣瀬
Original assignee: ナブテスコ株式会社
Priority date: 2014-01-22
Filing date: 2014-12-15
Publication date: 2015-07-30
Also published as: DE112014006232T5; KR20160111439A; KR102236715B1; CN106415062A; TW201537066A; JP6285728B2; JP2015137705A; DE112014006232B4; TWI661140B

Abstract

A gear power transmission device is configured in such a manner that a carrier is supported by a case through a bearing. The bearing is provided with an inner race, an outer race, rollers, and a retainer. The rotation axes of the rollers are tilted relative to the center axis of the bearing. The retainer maintains the distance between adjacent rollers. In the gear power transmission device, the outer peripheral surface of the inner race and the inner peripheral surface of the outer race are not provided with ribs for restricting the movement of the rollers in the rotation axis direction. A groove for receiving the large-diameter-side end of the retainer is provided in either the case or the carrier.

Description

Gear transmission

This application claims priority based on Japanese Patent Application No. 2014-009579 filed on Jan. 22, 2014. The entire contents of that application are incorporated herein by reference. This specification discloses the technique regarding a gear transmission.

A gear transmission in which a carrier rotates relative to a case and the carrier or case forms an output unit is known. In such a gear transmission, the carrier is supported by the case via a bearing. Japanese Unexamined Patent Application Publication No. 2010-159774 discloses a gear transmission in which a cylindrical roller bearing is disposed between a case and a carrier. In the following description, Japanese Patent Application Laid-Open No. 2010-159774 is referred to as Patent Document 1. In the cylindrical roller bearing of Patent Document 1, the rotating shaft of the roller (roller) is inclined with respect to the center axis of the bearing, and constitutes an angular roller bearing. In the angular roller bearing of Patent Document 1, ribs for restricting the movement of the roller in the rotation axis direction are not provided on the outer peripheral surface of the inner race and the inner peripheral surface of the outer race.

When the rotation axis of the roller is inclined with respect to the bearing center axis, a force for moving the roller outward along the rotation axis acts on the roller during driving of the gear transmission. In Patent Document 1, the end of the retainer on the large-diameter side is brought into contact with the case to restrict the roller from moving outward. That is, when the roller tries to move outward, the outer periphery of the end portion on the large diameter side of the retainer comes into contact with the case, and the movement of the roller in the axial direction is restricted. However, when the force applied to the roller becomes large, the retainer may slide with respect to the case, and the movement of the roller cannot be regulated. As a result, the roller may contact the case and the roller and / or the case may wear. The present specification solves the above-described problem and discloses a technique for more reliably regulating the movement of the roller in the axial direction.

The technology disclosed in this specification relates to a gear transmission in which a carrier is supported by a case via a bearing. The bearing includes an inner race provided on the carrier, an outer race provided on the case, a plurality of rollers disposed between the inner race and the outer race, and a retainer that maintains an interval between adjacent rollers. It has. The roller has a rotation axis inclined with respect to the bearing center axis. In the bearing, ribs for restricting the movement of the roller in the direction of its own rotation axis are not provided on the outer peripheral surface of the inner race and the inner peripheral surface of the outer race. In the gear transmission disclosed in this specification, a groove is provided in either one of the case and the carrier to accommodate the end portion on the large diameter side of the retainer.

According to the gear transmission described above, when the force that moves the roller to the outside along the rotation axis direction acts on the roller, the large diameter side of the retainer is accommodated in the groove. Even if the force for moving the roller in the axial direction increases, the retainer continues to stay in the groove, and the roller is prevented from moving further outward. Said gear transmission can regulate more reliably that a roller moves to a rotating shaft direction compared with the conventional gear transmission.

Note that “the inner race is provided on the carrier” not only means that the inner race, which is a part different from the carrier, is fixed to the carrier, but also that the carrier is processed by machining the outer peripheral surface of the carrier. The form which functions as is also included. Similarly, “the outer race is provided in the case” means not only a form in which the outer race, which is a separate part from the case, is fixed to the case, but also the case by processing the inner peripheral surface of the case. The form which functions as an outer race is also included.

Sectional drawing of the gear transmission of 1st Example is shown. The expanded sectional view of the part enclosed with the broken line II of FIG. 1 is shown. The expanded sectional view of a part of gear transmission of 2nd Example is shown. Sectional drawing of the gear transmission of 3rd Example is shown. The expanded sectional view of the part enclosed with the broken line V of FIG. 4 is shown. The expanded sectional view of a part of gear transmission of 4th Example is shown. The figure for demonstrating the characteristic of the retainer of 1st, 3rd Example is shown. The figure for demonstrating the characteristic of the retainer of 2nd, 4th Example is shown.

Hereinafter, some of the technical features of the gear transmission disclosed in this specification will be described. The items described below have technical usefulness independently.

The gear transmission has a carrier and a case. The carrier may be rotatably supported by the case via a bearing. A plurality of gears may be accommodated in the case. The gear transmission may further include a crankshaft, an eccentric rotation gear, and a rotation gear. The crankshaft may be rotatably supported by the carrier. The crankshaft may include an eccentric body. The eccentric rotating gear may engage with the eccentric body of the crankshaft and rotate eccentrically as the crankshaft rotates. The rotation gear meshes with the eccentric rotation gear, and may have a number of teeth different from the number of teeth of the eccentric rotation gear. The eccentric rotation gear may be an external gear, and the rotation gear may be an internal gear. Internal teeth are provided on the inner peripheral surface of the case, and the case may also serve as an internal gear.

The bearing may include an inner race, an outer race, and a plurality of rollers. The inner race may be provided in the carrier. The inner race may be fixed to the outer peripheral surface of the carrier, or the outer peripheral surface of the carrier may function as the inner race. The outer race may be provided in the case. An outer race may be fixed to the inner peripheral surface of the case, and the inner peripheral surface of the case may function as an outer race. The plurality of rollers may be disposed between the inner race and the outer race.

The outer race surface of the inner race does not need to be provided with ribs for restricting the movement of the roller in the direction of the rotation axis. That is, the protrusion part which contacts the edge part of the rotating shaft direction of a roller does not need to be provided in the outer peripheral surface of the inner race. A rib for restricting the movement of the roller in the direction of the rotation axis may not be provided on the inner peripheral surface of the outer race. That is, the protrusion part which contacts the edge part of the rotating shaft direction of a roller does not need to be provided in the internal peripheral surface of an outer race.

The plurality of rollers may have a rotating shaft inclined with respect to the bearing central axis of the bearing. The roller may be cylindrical or conical. When the roller is cylindrical, the bearing is a cylindrical roller bearing (angular roller bearing). When the roller is conical, the bearing is a tapered roller bearing. The rotating shaft of the roller may be inclined so as to approach the bearing central axis of the bearing as it goes toward the inside of the gear transmission (center side in the axial direction of the gear transmission). When the bearing is a tapered roller bearing, the small diameter portion of the roller may be located inside the gear transmission from the large diameter portion.

The bearing may include a retainer that keeps the interval between adjacent rollers. The retainer has a ring shape and may include a large diameter portion and a small diameter portion. The small diameter part of the retainer may be located inside the gear transmission from the large diameter part of the retainer. A plurality of holes (pockets) may be provided in the circumferential direction of the retainer, and the roller may be disposed in the holes. A groove may be provided in the case for accommodating the end portion on the large diameter side of the retainer. Or the groove | channel which accommodates the edge part by the side of the large diameter of a retainer may be provided in the carrier. The end of the retainer on the large diameter side may always be in contact with the bottom surface of the groove. Alternatively, the end portion on the large diameter side of the retainer may contact the bottom surface of the groove when a force that moves the roller outward acts on the roller. The end surface on the large-diameter side of the retainer may have a circular shape that goes around the bearing central axis. That is, the end surface on the large diameter side of the retainer may be flat. In this case, the entire circumference of the end portion on the large diameter side of the retainer is accommodated in the groove. Alternatively, the end surface on the large diameter side of the retainer may have irregularities. That is, the end portion on the large diameter side of the retainer may have a configuration in which a part in the circumferential direction protrudes. In this case, at least a part (projection) of the end portion on the large diameter side of the retainer is accommodated in the groove.

The large diameter portion of the retainer may extend in a direction different from the rotation axis of the roller toward the end portion. In other words, the retainer may be bent in a direction different from the rotation axis of the roller outside the outer end surface of the roller (the end surface of the roller located on the large diameter side of the retainer). The angle between the direction in which the large-diameter portion of the retainer extends and the bearing center axis may be smaller than the angle between the rotation axis of the roller and the bearing center axis. In this case, the groove for accommodating the end portion on the large diameter side of the retainer may be provided in the carrier. The “angle between the rotation axis of the roller and the center axis of the bearing” means “acute angle”. The “angle between the direction in which the large diameter portion of the retainer extends and the bearing center axis” includes 0 degrees. That is, the large diameter portion of the retainer may extend parallel to the bearing central axis.

The angle between the direction in which the large-diameter portion of the retainer extends and the bearing center axis may be larger than the angle between the roller rotation axis and the bearing center axis. The angle between the direction in which the large-diameter portion of the retainer extends and the bearing central axis may be 90 degrees. That is, the end of the retainer on the large diameter side may extend in a direction perpendicular to the bearing central axis.

(First embodiment)
The gear transmission 100 will be described with reference to FIG. In the following description, parts having substantially the same function may be described by omitting alphabetical symbols attached to reference numerals. The gear transmission 100 includes an internal gear 48, a carrier 2, a crankshaft 10, and an external gear 14. The internal gear 48 includes a case 46 and a plurality of internal gear pins 44. The case 46 surrounds the outside in the radial direction of the external gear 14. The internal tooth pin 44 has a cylindrical shape and is disposed on the inner peripheral surface of the case 46. The carrier 2 is rotatably supported by the case 46 by a pair of

first bearings

40 and 60. The internal tooth pin 44 is disposed between the

first bearings

40 and 60. The

first bearings

40 and 60 restrict the carrier 2 from moving in the axial direction and the radial direction with respect to the case 46. In the gear transmission 100, tapered roller bearings are used as the

first bearings

40 and 60.

The first bearing 40 is disposed between the case 46 and the carrier 2 (second plate 2c). The first bearing 40 includes an inner race 30, an outer race 36, a roller 34, and a retainer 32. The inner race 30 is integral with the carrier 2. More specifically, the outer peripheral surface of the carrier 2 also serves as the inner race 30. That is, the inner race 30 is a part of the carrier 2. The outer race 36 is attached to the case 46. The outer race 36 is fitted into the inner peripheral surface of the case 46. The first bearing 40 includes a plurality of rollers 34. FIG. 1 shows a part of the plurality of rollers 34.

The outer peripheral surface of the inner race 30 and the inner peripheral surface of the outer race 36 are not provided with a protruding portion that protrudes toward the rotating shaft 38. That is, the outer peripheral surface of the inner race 30 and the inner peripheral surface of the outer race 36 are not provided with ribs for restricting the movement of the roller 34 in the direction of the rotation shaft 38. An interval between adjacent rollers 34 is held by a retainer 32. Specifically, a plurality of holes (not shown) are provided in the circumferential direction of the retainer 32, and a roller 34 is disposed in each hole. The rotation shaft 38 of the roller 34 is inclined with respect to the axis 26 of the gear transmission 100. The axis 26 is a rotation axis of the carrier 2 or the case 46, and is also a bearing central axis of the first bearing 40.

The first bearing 60 is disposed between the case 46 and the carrier 2 (first plate 2a). The first bearing 60 includes an inner race 50, an outer race 56, a roller 54, and a retainer 52. The inner race 50 is integral with the carrier 2. The outer peripheral surface of the carrier 2 also serves as the inner race 50. That is, the inner race 50 is a part of the carrier 2. The outer race 56 is attached to the case 46. The outer race 56 is fitted into the inner peripheral surface of the case 46. The first bearing 60 includes a plurality of rollers 54.

The outer peripheral surface of the inner race 50 and the inner peripheral surface of the outer race 56 are not provided with a protruding portion that protrudes toward the rotating shaft 38. That is, the outer peripheral surface of the inner race 50 and the inner peripheral surface of the outer race 56 are not provided with ribs for restricting the roller 54 from moving in the direction of the rotation shaft 58. An interval between adjacent rollers 54 is held by a retainer 52. A plurality of holes (not shown) are provided in the circumferential direction of the retainer 52, and a roller 54 is disposed in each hole. A rotation shaft 58 of the roller 54 is inclined with respect to the axis 26. The

rotary shafts

38 and 58 approach the axis 26 as they go inward of the gear transmission 100. The inclination angle of the rotation shaft 38 with respect to the axis 26 is equal to the inclination angle of the rotation shaft 58 with respect to the axis 26. That is, the position where the rotation shaft 38 and the rotation shaft 58 intersect is the midpoint between the first bearing 40 and the first bearing 60 in the direction of the axis 26.

The carrier 2 includes a first plate 2a and a second plate 2c. The first plate 2a includes a columnar portion 2b. The columnar portion 2b extends from the first plate 2a toward the second plate 2c, and is fixed to the second plate 2c. The first plate 2a and the second plate 2c are detachable. An oil seal 12 is provided between the first plate 2 a and the case 46. Further, the gear transmission 100 includes a through hole 4 along the axis 26. That is, a through hole is provided in the center of the carrier 2 and the external gear 14.

The crankshaft 10 is supported on the carrier 2 by a pair of second bearings 6. The second bearing 6a is attached to the first plate 2a, and the second bearing 6b is attached to the second plate 2c. The pair of second bearings 6 restricts the crankshaft 10 from moving relative to the carrier 2 in the axial direction and the radial direction. In the gear transmission 100, tapered roller bearings are used as the pair of second bearings 6.

The crankshaft 10 includes a shaft portion 8 (8a, 8b) and two eccentric bodies 18 (18a, 18b). The

eccentric bodies

18a and 18b are provided between the

shaft portions

8a and 8b. The second bearing 6 is fixed to the shaft portion 8. Therefore, it can also be said that the eccentric body 18 is disposed between the

second bearings

6a and 6b. The eccentric body 18a and the eccentric body 18b are symmetrical in the direction of eccentricity with respect to the rotating shaft 24 of the crankshaft 10. The eccentric body 18a is engaged with the external gear 14a via the cylindrical roller bearing 16a. The eccentric body 18b is engaged with the external gear 14b via the cylindrical roller bearing 16b. The cylindrical roller bearing 16 is restricted by the second bearing 6 from moving in the axial direction (direction of the rotary shaft 24).

The input gear 22 is fixed to the shaft portion 8b. The input gear 22 is fixed to the shaft portion 8b outside the

second bearings

6a and 6b. Torque of a motor (not shown) is transmitted to the input gear 22. When the motor torque is transmitted to the input gear 22, the crankshaft 10 rotates around the rotation shaft 24. When the crankshaft 10 rotates, the eccentric body 18 rotates eccentrically around the rotation shaft 24. As the eccentric body 18 rotates eccentrically, the external gear 14 rotates eccentrically while meshing with the internal gear 48. The external gear 14 rotates eccentrically around the axis 26. The external gear 14 a and the external gear 14 b rotate eccentrically symmetrically with respect to the axis 26. The number of teeth of the external gear 14 and the number of teeth of the internal gear 48 (number of internal pins 44) are different. The external gear 14 is supported by the carrier 2 via the crankshaft 10. Therefore, when the external gear 14 rotates eccentrically, the carrier 2 rotates relative to the internal gear 48 (case 46) according to the difference in the number of teeth between the external gear 14 and the internal gear 48.

The first bearing 40 will be described in detail with reference to FIG. Note that the structure of the first bearing 60 is substantially the same as the structure of the first bearing 40. Therefore, description of the first bearing 60 may be omitted.

As shown in FIG. 2, the large diameter portion 32 a of the retainer 32 extends in a direction different from the rotation shaft 38. Specifically, the retainer 32 extends along the rotation shaft 38 from the end of the small diameter portion to the end of the roller 34 on the large diameter portion 32a side, and from the end of the roller 34 on the large diameter portion 32a side. The end of the large diameter portion 32a extends along the bearing central axis 26 (see also FIG. 1). The end surface of the large-diameter portion 32 a of the retainer 32 has a circular shape that makes a round around the bearing central axis 26. The dashed-dotted line 32b of FIG. 2 has shown the direction where the large diameter part 32a is extended. The alternate long and short dash line 32 b is parallel to the bearing center axis 26. It can also be said that the larger diameter side of the retainer 32 is bent in a direction different from the rotation shaft 38. Alternatively, it can also be said that a protruding portion 32 a protruding in a direction different from the rotation shaft 38 is provided on the large diameter side of the retainer 32.

FIG. 7 shows the angle of the rotation axis 38 of the roller 34 and the direction 32b in which the large diameter portion 32a extends with respect to the bearing center shaft 26. FIG. 7 is a diagram for explaining an angle formed by each line (axis), and does not accurately indicate the position of the actual line (axis). As described above, the direction 32b in which the large-diameter portion 32a extends is parallel to the bearing center axis 26. The angle between the bearing center shaft 26 and the direction 32b is 0 degree. Further, the angle θ ₁ between the bearing center shaft 26 and the rotary shaft 38 is approximately 40 degrees. That is, the retainer 32 extends from the small diameter side to the large diameter side to the end of the roller 34 on the large diameter portion 32a side at an angle of about 40 degrees with respect to the bearing center shaft 26, and the large diameter portion of the roller 34 After exceeding the end portion on the 32a side, the shaft extends parallel to the bearing central axis 26 (an angle of 0 degrees). The angle between the bearing center shaft 26 and the direction 32 b is smaller than the angle θ ₁ between the bearing center shaft 26 and the rotating shaft 38.

As shown in FIG. 2, a groove 62 is provided in the carrier 2. The groove 62 makes a round around the axis 26. The groove 62 is formed at a position facing the end surface of the large diameter portion 32a. The groove 62 accommodates the end portion of the large diameter portion 32a. As described above, the end surface of the large-diameter portion 32 a has a circular shape that goes around the bearing central axis 26. Therefore, the entire circumference of the large diameter portion 32 a is accommodated in the groove 62. When a force that moves the roller 34 to the outside (the outside of the gear transmission 100 in the direction of the rotation shaft 38) is applied to the roller 34, the retainer 32 moves outward together with the roller 34, and the retainer 32 contacts the carrier 2. The movement of the retainer 32 is restricted, and as a result, the movement of the roller 34 in the direction of the rotation shaft 38 is restricted. Similarly, when a force that moves the roller 54 outward is applied to the roller 54, the movement of the retainer 52 is restricted, and the movement of the roller 54 in the direction of the rotation shaft 38 is restricted (see FIG. 1).

The advantages of the gear transmission 100 will be described. The advantages of the first bearing 40 and the first bearing 60 are the same. Therefore, only the first bearing 40 will be described below, and the description of the first bearing 60 will be omitted. When the gear transmission 100 is driven, a force that moves the roller 34 to the outside is applied to the roller 34. The inner race 30 and the outer race 36 do not include a rib that restricts the movement of the roller 34. Therefore, the inner race 30 and the outer race 36 do not contact the end of the roller 34 in the direction of the rotation axis 38. It is possible to prevent the roller 34 from being worn.

As described above, the outward movement of the roller 34 is regulated by the retainer 32 coming into contact with the carrier 2. More specifically, when the end surface of the large-diameter portion 32 a of the retainer 32 is in contact with the bottom surface of the groove 62, the movement of the roller 34 is restricted. When the retainer 32 comes into contact with the bottom surface of the groove 62, the end portion of the large diameter portion 32 a of the retainer 32 is accommodated in the groove 62. Even if the force for moving the roller 34 to the outside increases, the retainer 32 stays in the groove 62, and the movement of the roller 34 to the outside can be restricted.

The gear transmission 100 can continue to restrict the movement of the roller 34 after the retainer 32 contacts the carrier 2 as long as the retainer 32 is not damaged. On the other hand, as described above, the conventional gear transmission restricts the roller from moving outward by bringing the large diameter portion of the retainer into contact with the case. For this reason, when the force for moving the roller outward increases, the retainer slides on the case, and the movement of the roller cannot be restricted. The gear transmission 100 can more reliably regulate the movement of the roller than the conventional gear transmission.

As is clear from FIG. 1, the large diameter portion 32 a of the retainer 32 does not contact the case 46. Therefore, the retainer 32 can prevent the gap between the case 46 and the carrier 2 from being blocked. In the gear transmission 100, the lubricant or the like can easily move in and out of the first bearing 40.

(Second embodiment)
The gear transmission 200 will be described with reference to FIG. The gear transmission 200 is a modification of the gear transmission 100, and the same components as the gear transmission 100 may be denoted by the same reference numerals or the same two lower digits, and the description thereof may be omitted. The gear transmission 200 is different from the gear transmission 100 in that the first bearing forms a cylindrical roller bearing (angular roller bearing). FIG. 3 shows only a part of the gear transmission 200 (part corresponding to FIG. 2). The gear transmission 200 includes a pair of first bearings as in the gear transmission 100 (see also FIG. 1). However, only the first bearing 240 provided between the case 46 and the second plate 202c will be described below. The other structure of the gear transmission 200 is substantially the same as that of the gear transmission 100.

The first bearing 240 includes an inner race 230, an outer race 236, a roller 234, and a retainer 232. The outer peripheral surface of the carrier 202 (202c) also serves as the inner race 230. The outer peripheral surface of the inner race 230 and the inner peripheral surface of the outer race 236 have the same inclination angle with respect to the axis 26. The roller 234 is cylindrical. The large diameter portion 232 a of the retainer 232 extends in a direction 232 b different from the rotation shaft 238.

FIG. 8 shows an angle in a direction 232b in which the rotation shaft 238 of the roller 234 and the large diameter portion 232a extend with respect to the bearing center shaft 26. A direction 232b in which the large diameter portion 232a extends is parallel to the bearing center axis 26. That is, the angle between the bearing center shaft 26 and the direction 32b is 0 degree. The angle θ ₃ between the bearing center shaft 26 and the rotating shaft 238 is approximately 45 degrees. The angle between the bearing center shaft 26 and the direction 32 b is smaller than the angle θ ₃ between the bearing center shaft 26 and the rotating shaft 238.

(Third embodiment)
The gear transmission 300 will be described with reference to FIGS. The gear transmission 300 is a modification of the gear transmission 100, and the same components as the gear transmission 100 may be denoted by the same reference numerals or the lower two digits with the same reference numerals, and description thereof may be omitted. The gear transmission 300 is different from the gear transmission 100 in the structure of the pair of

first bearings

340 and 360 and the surrounding structure. In the following description, the first bearing 340 will be described, and the description of the first bearing 360 may be omitted.

The

first bearings

340 and 360 are disposed between the case 46 and the carrier 2. The first bearing 340 is disposed between the case 46 and the carrier 2 (second plate 2c), and the first bearing 360 is disposed between the case 46 and the carrier 2 (first plate 2a). The first bearing 340 includes an inner race 30, an outer race 36, a roller 34, and a retainer 332. A large diameter portion 332 a of the retainer 332 extends in a direction 332 b different from the rotation shaft 38. The retainer 332 extends from the end portion of the small diameter portion to the end portion of the roller 34 on the large diameter portion 32a side so as to be separated from the bearing center shaft 26 along the rotation shaft 38. The retainer 332 extends from the end of the roller 34 on the large-diameter portion 332a side to the end of the large-diameter portion 332a so as to be farther from the bearing center shaft 26 than the rotation shaft 38. The large diameter portion 332 a extends toward the case 346.

A groove 362 is provided in the case 346. The groove 362 makes a round around the axis 26. An end portion of the large diameter portion 332 a is accommodated in the groove 362. In the same manner as the gear transmission 100, the gear transmission 300 restricts the retainer 32 from staying in the groove 362 and moving the roller 34 outward even when a force that moves the roller 34 outward is applied to the roller 34. be able to.

As shown in FIG. 7, the angle θ ₂ between the bearing center shaft 26 and the direction 332 _b is larger than the angle θ ₁ between the bearing center shaft 26 and the rotation shaft 38. The angle θ ₂ is approximately 90 degrees and the angle θ ₁ is approximately 40 degrees. That is, the retainer 332 extends from the small diameter side toward the large diameter side to the end on the large diameter portion 32a side of the roller 34 at an angle of about 40 degrees with respect to the bearing center shaft 26, and the large diameter portion of the roller 34 It extends in a direction orthogonal to the bearing central shaft 26 so as to leave the bearing central shaft 26 after exceeding the end portion on the 32a side.

(Fourth embodiment)
The gear transmission 400 will be described with reference to FIG. The gear transmission 400 is a modification of the

gear transmissions

200 and 300, and the same components as the

gear transmissions

200 and 300 may be denoted by the same reference numerals or the same two lower digits, and the description thereof may be omitted. The gear transmission 400 is different from the gear transmission 200 in that the case 362 is provided with a groove 362 that accommodates the end of the large-diameter portion 432a of the retainer 432 (see also FIG. 3). Alternatively, the gear transmission 400 is different from the gear transmission 300 in that the first bearing 440 forms a cylindrical roller bearing (angular roller bearing) (see also FIG. 5). In the following description, only the first bearing 440 provided between the case 346 and the second plate 402c of the pair of first bearings will be described.

The first bearing 440 includes an inner race 430, an outer race 236, a roller 234, and a retainer 432. The outer peripheral surface of the carrier 402 (402c) also serves as the inner race 430. The large diameter portion 432 a of the retainer 432 extends in a direction 432 b different from the rotation shaft 238. The retainer 432 extends from the end portion of the small diameter portion to the end surface of the roller 234 on the large diameter portion 432a side so as to be separated from the bearing center shaft 26 along the rotation shaft 238. The retainer 432 extends from the end surface of the roller 234 on the large-diameter portion 432a side to the end of the large-diameter portion 432a so as to be away from the bearing central shaft 26 at a steeper angle than the rotation shaft 238. The large diameter portion 432a extends toward the case 346.

As shown in FIG. 8, the angle θ ₄ between the bearing center shaft 26 and the direction 432 b is larger than the angle θ ₃ between the bearing center shaft 26 and the rotating shaft 238. The angle θ ₄ is approximately 90 degrees and the angle θ ₃ is approximately 45 degrees. That is, the retainer 432 extends at an angle of about 45 degrees with respect to the bearing center shaft 26 from the small diameter portion side to the large diameter portion side to the end portion of the roller 234 on the large diameter portion 432a side. It extends in a direction perpendicular to the bearing center shaft 26 so as to be separated from the bearing center shaft 26 after exceeding the end on the diameter portion 432a side.

In the above embodiment, a description has been given of a form in which the end surface on the large-diameter side of the retainer has a circular shape that goes around the center axis of the bearing. Such a retainer has an advantage that the movement of the retainer is easily regulated since the entire circumference of the large diameter portion is accommodated in the groove. The technology disclosed in this specification can also be applied to a form in which the end surface on the large diameter side of the retainer has irregularities. Such a retainer can reduce the contact area when the end surface of the retainer contacts the bottom surface of the groove, and can reduce friction between the case (or carrier) and the retainer.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Claims

A gear transmission in which a carrier is supported by a case via a bearing;
The bearing is
With the inner race provided in the carrier,
An outer race provided in the case;
A plurality of rollers disposed between the inner race and the outer race and having a rotation axis inclined with respect to the bearing center axis;
A retainer that holds the interval between adjacent rollers,
There are no ribs on the outer peripheral surface of the inner race and the inner peripheral surface of the outer race to restrict the roller from moving in the direction of the rotation axis,
A gear transmission in which either one of the case and the carrier is provided with a groove for accommodating the end portion on the large diameter side of the retainer.
The gear transmission according to claim 1, wherein the large-diameter portion of the retainer extends in a direction different from the rotation axis direction toward the end portion.
The angle between the direction in which the large-diameter portion of the retainer extends and the bearing center axis is smaller than the angle between the rotating shaft and the bearing center axis,
The gear transmission according to claim 2, wherein the groove is formed in the carrier.
The gear transmission according to claim 3, wherein the large-diameter portion of the retainer extends in parallel with the bearing central axis.
The angle between the direction in which the large diameter portion of the retainer extends and the bearing central axis is larger than the angle between the rotating shaft and the bearing central axis,
The gear transmission according to claim 2, wherein the groove is formed on an inner peripheral surface of the case.
The gear transmission according to claim 5, wherein the large-diameter portion of the retainer extends in a direction orthogonal to the bearing central axis.