JP2013224700A - Gear transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear transmission capable of suppressing the deterioration of a tapered roller bearing arranged between a casing and a carrier.SOLUTION: A carrier 10 is supported on a casing 4 via a tapered roller bearing 2 in a gear wheel drive 100. The tapered roller bearing 2 comprises an inner race 46, an outer race 40, tapered rollers 42 and a retainer 44. The inner race 46 is mounted to a carrier 10. The outer race 40 is mounted to a casing 4. The tapered rollers 42 are positioned between the inner race 46 and the outer race 40. The outer peripheral surface of the inner race 46 and the inner peripheral surface of the outer race 40 are not provided with ribs that restrict the tapered rollers 42 from moving in a direction away from the central axis of the bearings. The end 44a where the diameter of the retainer 44 is the greatest comes into contact with the carrier 10 in the central axis direction of the bearing, and comes into contact with the casing 4 in a direction perpendicular to the central axis of the bearing.

Description

  The present invention relates to a gear transmission. In particular, the present invention relates to a gear transmission provided with a tapered roller bearing between a carrier and a case.

  A gear transmission in which a gear group is accommodated in a case and a carrier is supported by the case via a bearing is known. Patent Document 1 discloses a gear transmission in which a tapered roller bearing is disposed between a case and a carrier. In the case of a tapered roller bearing, it is necessary to constrain the end surface on the large diameter side of the tapered roller in order to restrict the tapered roller from moving in the axial direction. In the technique of Patent Document 1, a rib is formed on the outer peripheral surface of the inner race, and the rib is brought into contact with the end surface on the large diameter side of the tapered roller. In the present specification, for the sake of simplicity, the “conical roller” may be simply referred to as “roller” below.

JP 2008-240852 A

  When the rib formed on the outer peripheral surface of the inner race is brought into contact with the roller as in Patent Document 1, the end surface of the roller may be worn. Thereby, the deterioration of the tapered roller bearing is promoted, and the durability of the gear transmission is lowered. This specification provides the technique which suppresses deterioration of the tapered roller bearing arrange | positioned between a case and a carrier. In many gear transmissions, the carrier rotates as an output shaft, but in some types of gear transmissions, the case rotates as an output shaft. In the following, for the sake of simplicity of explanation, a gear transmission in which the case is stationary and the carrier rotates as an output shaft will be described.

  The technology disclosed in this specification relates to a gear transmission in which a carrier is supported by a case via a tapered roller bearing. In the gear transmission, the tapered roller bearing includes an inner race attached to the carrier, an outer race attached to the case, a plurality of tapered rollers disposed between the inner race and the outer race, and an inner race. It is disposed between the race and the outer race, and is provided with a ring-shaped retainer that maintains the interval between the adjacent tapered rollers. In this gear transmission, the small diameter portion of the tapered roller is located closer to the bearing center shaft than the large diameter portion of the tapered roller. More precisely, the center of the small diameter portion of the tapered roller is located closer to the bearing center shaft than the center of the large diameter portion of the tapered roller. On the outer peripheral surface of the inner race and the inner peripheral surface of the outer race, there is no rib that restricts the tapered roller from moving in a direction away from the bearing central axis. More specifically, the rib that contacts the large diameter portion of the tapered roller is not provided on either the inner race or the outer race. The retainer is made of a material having lower rigidity than the carrier and the case. Further, the retainer is provided with a carrier contact surface and a case contact surface at the end of the larger diameter. The carrier contact surface is in contact with the carrier in the bearing central axis direction. The case contact surface contacts the case in a direction orthogonal to the bearing central axis.

  According to the above gear transmission, the retainer regulates the movement of the tapered roller (roller) to the outside (the direction away from the bearing center axis) by contacting both the case and the carrier. Since the end surface of the roller does not contact other parts (ribs), wear of the end surface of the roller can be suppressed. As a result, the deterioration of the tapered roller bearing can be suppressed. The retainer need not always be in contact with both the case and the carrier. While the gear transmission is stationary, the retainers (case contact surface and carrier contact surface) may be separated from the case and the carrier. The retainer may be in contact with both the case and the carrier when a force is applied to the roller to move the roller outward while the gear transmission is being driven. Further, the above gear transmission has various advantages in addition to the advantage of suppressing the wear of the end face of the roller. Some of these advantages are described below.

  As a first advantage, the rotational speed of the retainer can be made close to the rotational speed when the retainer does not contact either the case or the carrier. For example, when the retainer contacts only the carrier, friction is generated between the retainer and the carrier, the rotation speed of the retainer becomes slow, and the moving speed of the roller becomes slow. As a result, the sliding of the roller is increased, and the peripheral surface of the roller is easily worn. If the retainer contacts both the carrier and the case, the sliding of the roller can be reduced, and the wear on the peripheral surface of the roller can be suppressed.

  As a second advantage, since the retainer contacts both the carrier and the case, it is possible to prevent foreign matters from being mixed into the gear transmission from the outside of the gear transmission during the driving of the gear transmission. As a result, foreign matter is prevented from entering the inside of the tapered roller bearing, and the progress of roller wear is suppressed.

  As a third advantage, since the retainer is formed of a material having rigidity lower than that of the carrier and the case, the retainer uniformly contacts the carrier and the case in the circumferential direction. An example of the retainer material is a resin.

  As a fourth advantage, it is possible to easily process the inner race and / or the outer race. When ribs are provided on the outer peripheral surface of the inner race and / or the inner peripheral surface of the outer race, it is necessary to polish the surface of the rib (contact surface with the roller). Since the gear transmission does not have a rib for restricting the movement of the roller in the axial direction, the processing cost of the inner race and / or the outer race can be reduced.

  As a fifth advantage, the length of the roller in the axial direction can be increased by the amount that the rib is not formed. Thereby, the capacity | capacitance (load load) of a tapered roller bearing can be improved.

Sectional drawing of the gear transmission of 1st Example is shown. FIG. 2 shows an enlarged sectional view of a range II in FIG. 1. The schematic of the external appearance of a retainer is shown. The figure which looked at the retainer from the bearing central axis direction (plan view) is shown. The figure (front view) which looked at the retainer from the direction orthogonal to a bearing central axis is shown. The figure for demonstrating operation | movement of a roller is shown. The top view of the retainer used with the gear transmission of 2nd Example is shown. The front view of the retainer used with the gear transmission of 2nd Example is shown. The top view of the retainer used with the gear transmission of 3rd Example is shown. The front view of the retainer used with the gear transmission of 3rd Example is shown. Sectional drawing of the gear transmission of 4th Example is shown.

  In the following embodiments, a gear transmission using a retainer in which grooves are formed on both the carrier contact surface and the case contact surface will be described. However, in the technology disclosed in this specification, the gear transmission using a retainer in which a groove is formed on one of the carrier contact surface and the case contact surface, and the groove is formed on both the carrier contact surface and the case contact surface. The present invention can also be applied to a gear transmission using a retainer that is not formed.

  If a groove is formed on at least one of the carrier contact surface and the case contact surface, the following advantages are obtained. When the retainer comes into contact with the case and the carrier, a passage for the lubricant from the outside to the inside of the tapered roller bearing is secured. That is, even if the retainer contacts the carrier and the case, the lubricant can move through the groove and into the tapered roller bearing. As a result, the progress of roller wear is further suppressed. In addition, the technique which forms a groove | channel in at least one of a carrier contact surface and a case contact surface has technical usefulness independently.

  In the embodiment, a gear transmission device in which the external gear rotates eccentrically while meshing with the internal gear will be described. It should be noted that the technology disclosed in the present specification can also be applied to other types of gear transmissions, for example, gear transmissions in which an internal gear rotates eccentrically while meshing with an external gear.

(First embodiment)
FIG. 1 shows a cross-sectional view of the gear transmission 100. The gear transmission 100 is a type of reduction gear that rotates eccentrically while the external gear 22 meshes with the internal gear 24. In the gear transmission 100, the carrier 10 is rotated using the difference between the number of teeth of the external gear 22 and the number of teeth of the internal gear 24. The gear transmission 100 increases the torque transmitted to the crankshaft 16 (decelerates rotation) and outputs it from the carrier 10 using the above-described difference in the number of teeth. The carrier 10 corresponds to the output shaft of the gear transmission 100. The axis 30 corresponds to the rotation axis of the carrier 10. The axis 30 corresponds to the axis of the gear transmission 100. Further, the axis 30 corresponds to a bearing central axis of the tapered roller bearing 2 described later.

  The gear transmission 100 includes an internal gear 24, a carrier 10, an external gear 22, and a crankshaft 16. The internal gear 24 includes a case 4 and a plurality of internal gear pins 5. The case 4 has a small diameter portion 4a and a large diameter portion 4b. The small diameter portion 4a extends along the axis 30 from both ends of the large diameter portion 4b. The internal gear 24 is formed in the large diameter portion 4 b of the case 4. A pair of tapered roller bearings 2 is disposed in the small diameter portion 4a. The pair of tapered roller bearings 2 restricts the carrier 10 from moving in the axial direction and the radial direction. The tapered roller bearing 2 can be said to be a main bearing of the gear transmission 100. Details of the tapered roller bearing 2 will be described later.

  The carrier 10 is supported on the case 4 by a pair of tapered roller bearings 2. The carrier 10 includes a first plate 10a and a second plate 10c. A columnar portion 10b extends from the first plate 10a toward the second plate 10c, and the columnar portion 10b and the second plate 10c are fixed. A first flange 10d extending in the radial direction (a direction perpendicular to the axis 30) is formed at the end of the first plate 10a. A second flange 10e extending in the radial direction is formed at the end of the second plate 10c. The pair of tapered roller bearings 2 are disposed on the first flange 10d and the second flange 10e. The first flange 10d and the second flange 10e can also be referred to as protruding portions of the first plate 10a and the second plate 10c, respectively. The carrier 10 and the case 4 are made of metal.

  The crankshaft 16 is supported on the carrier 10 by a pair of tapered roller bearings 19. The pair of tapered roller bearings 19 restricts the crankshaft 16 from moving in the axial direction and the radial direction. The crankshaft 16 extends parallel to the axis 30 at a position offset from the axis 30. The crankshaft 16 includes an input gear 28 and an eccentric body 18. The input gear 28 is fixed to the crankshaft 16 outside the pair of tapered roller bearings 19. The eccentric body 18 is located between the pair of tapered roller bearings 19. A through hole 14 is formed in the external gear 22. The eccentric body 18 is engaged with the through hole 14 via the cylindrical roller bearing 20. The external gear 22 is supported by the carrier 10 via the crankshaft 16.

  When torque of a motor (not shown) is transmitted to the input gear 28, the crankshaft 16 rotates. As the crankshaft 16 rotates, the eccentric body 18 rotates eccentrically. The eccentric body 18 rotates eccentrically around the axis (not shown) of the crankshaft 16. As the eccentric body 18 rotates eccentrically, the external gear 22 rotates eccentrically while meshing with the internal gear 24. The external gear 22 rotates eccentrically around the axis 30. The number of teeth of the external gear 22 and the number of teeth of the internal gear 24 (the number of internal pins 5) are different. Therefore, when the external gear 22 rotates eccentrically, the carrier 10 that supports the external gear 22 is connected to the internal gear 24 (case 4) according to the difference in the number of teeth between the external gear 22 and the internal gear 24. Rotate against.

  The tapered roller bearing 2 will be described in detail with reference to FIG. The tapered roller bearing 2 includes an inner race 46, an outer race 40, a roller 42 (conical roller), and a retainer 44. The ring-shaped inner race 46 has a tapered outer peripheral surface 46b. That is, the outer peripheral surface 46b of the inner race 46 is inclined with respect to the axis 30 (see FIG. 1). The inner race 46 is press-fitted outside the second plate 10 c of the carrier 10. The inner peripheral surface 46a of the inner race 46 is in contact with the outer peripheral surface of the second plate 10c. An end face 46c in the direction of the axis 30 of the inner race 46 is in contact with the second flange 10e. The inner race 46 is attached to the carrier 10 and does not move with respect to the carrier 10 both in the direction of the axis 30 and in the radial direction. It can be said that the inner race 46 is integrated with the carrier 10.

  The ring-shaped outer race 40 has a tapered inner peripheral surface 40b. The inner peripheral surface 40 b of the outer race 40 faces the outer peripheral surface 46 b of the inner race 46. The outer race 40 is press-fitted inside the small diameter portion 4 a of the case 4. The outer peripheral surface 40a of the outer race 40 is in contact with the inner peripheral surface of the case 4 (small diameter portion 4a). An end surface 40 c in the direction of the axis 30 of the outer race 40 is in contact with the large diameter portion 4 b of the case 4. The outer race 40 is attached to the case 4 and is immovable with respect to the case 4 both in the direction of the axis 30 and in the radial direction. It can be said that the outer race 40 is integrated with the case 4.

  A gap between the inner circumferential surface 40b of the outer race 40 and the outer circumferential surface 46b of the inner race 46 (gap in which the roller 42 is disposed) becomes wider toward the outside (in the direction away from the bearing center shaft 30). In other words, the inclination angle of the inner peripheral surface 40 b with respect to the axis 30 is larger than the inclination angle of the outer peripheral surface 46 b with respect to the axis 30.

  The roller (conical roller) 42 is disposed between the inner race 46 and the outer race 40. The diameter of the roller 42 increases toward the outside. The diameter of the first end surface 42 a on the large diameter portion side of the roller 42 is larger than the diameter of the second end surface 42 b on the small diameter portion side of the roller 42. The rotation axis of the roller 42 is inclined with respect to the axis 30 (see FIG. 1). The center of the small diameter portion of the roller 42 is located closer to the bearing center shaft 30 than the center of the large diameter portion. A plurality of rollers 42 are arranged at equal intervals between the inner race 46 and the outer race 40. That is, the plurality of rollers 42 are arranged at equal intervals around the axis 30. The length of the roller 42 in the rotation axis direction is shorter than the lengths of the outer peripheral surface 46 b of the inner race 46 and the inner peripheral surface 40 b of the outer race 40. The outer peripheral surface of the roller 42 is in contact with the outer peripheral surface 46 b of the inner race 46 and the inner peripheral surface 40 b of the outer race 40. The first end surface 42 a and the second end surface 42 b are not in contact with the inner race 46 and the outer race 40.

  The retainer 44 is disposed between the inner race 46 and the outer race 40. The material of the retainer 44 is resin. As shown in FIG. 3, the retainer 44 has a ring shape, and has a first end 44a having a large diameter and a second end 44b having a smaller diameter than the first end 44a. The retainer 44 has a plurality of pockets 44c arranged in the circumferential direction. A roller 42 is inserted into the pocket 44c. The retainer 44 maintains an interval between the adjacent rollers 42. Further, since the roller 42 is inserted into the pocket 44 c, the first end surface 42 a and the second end surface 42 b of the roller 42 are restrained by the retainer 44. That is, the retainer 44 restricts the movement of the roller 42 in the rotation axis direction. FIG. 3 is a diagram for simply explaining the overall shape of the retainer 44, and does not accurately show the shape of the retainer 44. The detailed shape of the retainer 44 will be described later.

  As shown in FIG. 2, a case contact surface 44 d that contacts the case 4 and a carrier contact surface 44 e that contacts the carrier 10 are formed at the first end 44 a of the retainer 44. The case contact surface 44d is formed in a direction orthogonal to the axis 30 (see also FIG. 1). The case contact surface 44d is an outer peripheral surface of the retainer 44 and contacts the inner peripheral surface of the case 4 (small diameter portion 4a). A contact surface between the retainer 44 and the case 4 (a part of the case contact surface 44 d) has a cylindrical shape concentric with the axis 30. The carrier contact surface 44e is formed in the direction of the axis 30. The carrier contact surface 44e is an end surface of the retainer 44 in the bearing central axis (axis line 30) direction. The carrier contact surface 44e contacts the second flange 10e of the carrier 10 (second plate 10c) in the bearing central axis 30 direction. A contact surface between the retainer 44 and the carrier 10 (a part of the carrier contact surface 44 e) is orthogonal to the axis 30.

  Here, the retainer 44 will be described in detail with reference to FIGS. The case contact surface 44d is formed on the circumference concentric with the bearing center shaft 30 (the outer peripheral surface of the retainer 44). A plurality of outer peripheral grooves 44f are formed on the case contact surface 44d. The outer circumferential grooves 44 f extend along the bearing center axis 30 and are formed at equal intervals around the bearing center axis 30. It can also be expressed that the case contact surface 44d is formed between the adjacent outer peripheral grooves 44f. Even if the case contact surface 44 d contacts the case 4, the outer peripheral groove 44 f does not contact the case 4.

  The carrier contact surface 44e is formed on a plane orthogonal to the bearing central axis 30. A plurality of end face grooves 44g are formed on the carrier contact surface 44e. The end surface grooves 44 g extend along the radial direction of the retainer 44 and are formed at equal intervals around the bearing center shaft 30. It can also be expressed that the carrier contact surface 44e is formed between the adjacent end surface grooves 44g. The end surface groove 44g communicates the inside and the outside of the retainer 44. Even if the carrier contact surface 44 e contacts the carrier 10, the end surface groove 44 g does not contact the carrier 10.

  The outer peripheral grooves 44 f and the end surface grooves 44 g are alternately formed in the circumferential direction of the retainer 44. In other words, in the circumferential direction of the retainer 44, the outer peripheral groove 44f is formed between the adjacent end surface grooves 44g, and the end surface groove 44g is formed between the adjacent outer peripheral grooves 44f. The number of outer peripheral grooves 44f and end face grooves 44g are equal. The area of the case contact surface 44d is substantially equal to the area of the carrier contact surface 44e. That is, the area W1 of the contact surface between the retainer 44 and the case 4 shown in FIG. 2 is substantially equal to the area W2 of the contact surface between the retainer 44 and the carrier 10.

  In FIG. 2, the case contact surface 44e and the carrier contact surface 44e are in contact with the case 4 and the carrier 10, respectively. That is, the first end portion 44a of the retainer 44 is in contact with the case 4 in a direction perpendicular to the bearing center shaft 30 (the radial direction of the retainer 44), and in contact with the carrier 10 in the direction of the bearing center shaft 30. ing. When the gear transmission 100 is not driven, the case contact surface 44e and the carrier contact surface 44e may not be in contact with the case 4 and the carrier 10. What is important is that the case contact surface 44e and the carrier contact surface 44e come into contact with the case 4 and the carrier 10, respectively, when a force that moves outward is applied to the roller 42.

  The advantages of the gear transmission 100 will be described. While the gear transmission 100 is being driven, a force is applied to the roller 42 to move the roller 42 outward (in a direction away from the bearing center shaft 30). As described above, when the roller 42 tries to move outward, the first end 44 a of the retainer 44 comes into contact with the case 4 and the carrier 10. Therefore, the movement of the roller 42 in the direction of the rotation axis is restricted.

  Further, as described above, the outer peripheral surface 46b of the inner race 46 has a linear taper shape and does not have a rib. Similarly, the inner peripheral surface 40b of the outer race 40 is also linearly tapered and has no ribs. In other words, the outer peripheral surface 46b of the inner race 46 and the inner peripheral surface 40b of the outer race 40 are not provided with ribs that restrict the roller 42 from moving outward. More specifically, the outer peripheral surface 46b and the inner peripheral surface 40b are not provided with protrusions (ribs) that cover the first end 44a of the roller 42.

  The above features can also be expressed as follows. The outer peripheral surface 46b of the inner race 46 has a first region 46d and a second region 46e where the outer peripheral surface of the roller 42 does not contact. The diameter of the inner race 46 in the first region 46d is larger than the diameter of the inner race 46 in the second region 46e. That is, the thickness of the inner race 46 in the first region 46d is larger than the thickness of the inner race 46 in the second region 46e. Further, the inner peripheral surface 40b of the outer race 40 has a third region 40d and a fourth region 40e where the outer peripheral surface of the roller 42 does not contact. The diameter of the outer race 40 in the third region 40d is larger than the diameter of the outer race in the fourth region 40e. That is, the thickness of the outer race 40 in the third region 40d is smaller than the thickness of the outer race 40 in the fourth region 40e. The gap between the first region 46d and the third region 40d is not less than the diameter of the first end 44a of the roller 42.

  Due to the above characteristics, the first end surface 42 a of the roller 42 does not contact the inner race 46 and the outer race 40 even when a force for moving the roller 42 outward acts on the roller 42. As a result, the wear of the roller 42 is suppressed, and the deterioration of the tapered roller bearing 2 can be suppressed.

  In the tapered roller bearing 2, no rib is provided in the second region 46 e of the inner race 46 and the fourth region 40 e of the outer race 40. However, ribs may be provided in the second region 46e and / or the fourth region 40e. When the rib is provided in the second region 46e and / or the fourth region 40e, the roller 42 can be supported when the tapered roller bearing 2 is assembled. The assembly of the gear transmission 100 can be facilitated.

  Even if the second region 46e and / or the fourth region 40e are provided with ribs, the second end surface 42b of the roller 42 is hardly worn. As described above, the gap between the outer peripheral surface 46b of the inner race 46 and the inner peripheral surface 40b of the outer race 40 becomes wider toward the outside (in the direction away from the bearing center shaft 30). Further, the diameter of the roller 42 is increased toward the outside. Therefore, the roller 42 is restricted from moving inward (on the bearing center shaft 30 side). That is, even if a rib is provided in the second region 46e and / or the fourth region 40e, a large friction does not occur between the rib and the second end surface 42b.

  Another advantage of the gear transmission 100 will be described. As described above, the tapered roller bearing 2 is not provided with ribs in the first region 46 d of the inner race 46 and the third region 40 d of the outer race 40. That is, the tapered roller bearing 2 does not have a rib that is essential for restricting the movement of the roller in the conventional tapered roller bearing. In the prior art, in order to reduce friction between the rib and the end face of the roller, the surface of the rib must be polished. Therefore, the process which grind | polishes the surface of a rib was required. The gear transmission 100 can reduce the processing cost of the inner race and the outer race as compared with the conventional case.

  Further, the length in the axial direction of the roller 42 can be increased by the amount not having the rib, and the rolling surface of the roller 42 can be widened. As a result, the capacity (load load) of the tapered roller bearing 2 can be increased. That is, the gear transmission 100 can increase the capacity of the main bearing as compared with the conventional one without increasing the size of the main bearing (the tapered roller bearing 2).

  With reference to FIG. 6, another advantage of the gear transmission 100 will be described. FIG. 6 is a view for explaining the operation of the roller 42 and the retainer 44 when the carrier 10 rotates with respect to the stationary case 4. FIG. 6 is a view for explaining the concept of the operation of the roller 42 and the retainer 44, and does not accurately represent the structure of the gear transmission 100. Further, as described above, it can be said that the inner race 46 of the tapered roller bearing 2 is integrated with the carrier 10. Similarly, it can be said that the outer race 40 is integrated with the case 4. Therefore, in FIG. 6, the inner race 46 and the carrier 10 are shown as one part, and the outer race 40 and the case 4 are shown as one part. Moreover, the roller 42 shown in FIG. 6 shows the cross section orthogonal to a rotating shaft direction.

  When the carrier 10 rotates in the arrow A1 direction, the roller 42 moves in the arrow A3 direction while rotating in the arrow A2 direction. That is, the roller 42 moves in the arrow A3 direction while rolling on the outer peripheral surface of the carrier 10 and the inner peripheral surface of the case 4. The retainer 44 rotates in the arrow A3 direction as the roller 42 moves. In this case, if the friction between the roller 42 and the carrier 10 and the case 4 is small, the retainer 44 rotates at approximately half the rotation speed V of the carrier 10 (rotation speed 0.5 V). When the friction between the roller 42 and the carrier 10 increases, the speed of the roller 42 approaches the speed of the carrier 10. On the contrary, when the friction between the roller 42 and the case 4 increases, the speed of the roller 42 approaches the speed (zero) of the case 4.

  As described above, the first end portion 44a of the retainer 44 contacts both the case 4 and the carrier 10 (see also FIG. 2). When the retainer 44 comes into contact with both the case 4 and the carrier 10, a frictional force F1 is generated between the retainer 44 and the case 4 in the arrow A4 direction. Further, a frictional force F2 is generated between the retainer 44 and the carrier 10 in the direction of arrow A5. Since the contact area W1 between the retainer 44 and the case 4 is substantially equal to the contact area W2 between the retainer 44 and the carrier 10, the frictional force F1 and the frictional force F2 are substantially equal. The frictional force F1 and the frictional force F2 cancel each other, and the retainer 44 rotates in the arrow A3 direction at a speed close to the rotational speed of 0.5V. The roller 42 also moves in the arrow A3 direction at a speed close to the rotational speed 0.5V.

  As described above, the fact that the roller 42 moves at a speed close to the rotational speed 0.5V means that the friction of the roller 42 against the carrier 10 and the case 4 is small. In other words, the sliding of the roller 42 with respect to the carrier 10 and the case 4 is small. Therefore, wear of the outer peripheral surface (rolling surface) of the roller 42 is suppressed. For example, when the retainer 44 is brought into contact with only the case 4, only the frictional force corresponding to the frictional force F1 in FIG. 6 is generated, and the frictional force corresponding to the frictional force F2 cannot be obtained. Therefore, the rotation speed of the retainer 44 is slowed down, and the friction of the roller 42 against the case 4 is increased. Wear of the roller 42 is promoted, and the durability of the gear transmission is lowered. The gear transmission 100 shown in the present embodiment can suppress wear of the roller 42 while restricting movement of the roller 42 in the axial direction by bringing the retainer 44 into contact with both the carrier 10 and the case 4. .

  The tapered roller bearing 2 disposed between the case 4 and the first plate 10a has the same characteristics as the tapered roller bearing 2 disposed between the case 4 and the second plate 10c. Therefore, the description about the tapered roller bearing 2 arrange | positioned between the case 4 and the 1st plate 10a is abbreviate | omitted.

  The advantages of the gear transmission 100 will be further described. As described above, the contact surface between the retainer 44 and the case 4 is a cylindrical surface concentric with the axis 30. The contact surface between the retainer 44 and the carrier 10 is orthogonal to the axis 30. By having such a feature, the movement of the retainer 44 is restrained in two orthogonal directions (axial direction and radial direction). It is possible to reliably prevent the retainer 44 (roller 42) from coming off the gear transmission 100.

  The retainer 44 contacts both the case 4 and the carrier 10. For this reason, the retainer 44 can prevent foreign matter from entering the case 4 from the outside of the gear transmission 100. Further, an outer peripheral groove 44f is formed on the contact surface (case contact surface 44d) of the case 4 and the retainer 44, and an end surface groove 44g is formed on the contact surface (carrier contact surface 44e) of the carrier 10 and the retainer 44. Therefore, even if the retainer 44 contacts both the case 4 and the carrier 10, the lubricant present outside the tapered roller bearing 2 can be introduced into the tapered roller bearing 2. It is possible to prevent the lubricant in the tapered roller bearing 2 from being depleted (out of oil).

  When a force for moving the roller 42 outward acts on the roller 42, the retainer 44 is pressed against the case 4 and the carrier 10. As described above, the retainer 44 is made of resin, and the case 4 and the carrier 10 are made of metal. That is, the rigidity of the retainer 44 is lower than the rigidity of the case 4 and the carrier 10. Therefore, when the retainer 44 is pressed against the case 4 and the carrier 10, the retainer 44 is deformed, and the entire circumferential direction of the retainer 44 contacts the case 4 and the carrier 10 uniformly. That is, it is difficult to form a gap between the case contact surface 44 d and the case 4 and between the carrier contact surface 44 e and the carrier 10.

  An oil seal 6 is disposed between the case 4 and the first plate 10a, and a groove 26 is provided at a position facing the second plate 10c of the case 4 (see FIG. 1). An O-ring (not shown) is disposed in the groove 26 when another component (for example, a motor) is attached. The oil seal 6 and the O-ring (not shown) can prevent the lubricant sealed in the gear transmission 100 from leaking out of the gear transmission 100. The lubricant present in the vicinity of the oil seal 6 can be introduced into the tapered roller bearing 2 through the outer peripheral groove 44f and the end face groove 44g.

(Second embodiment)
The gear transmission of the second embodiment will be described with reference to FIGS. The gear transmission of this embodiment is different from the gear transmission 100 only in the shape of the retainer. Specifically, the retainer 144 of the present embodiment is different from the retainer 44 in the positional relationship between the outer peripheral groove formed on the case contact surface and the end surface groove formed on the carrier contact surface. Features common to the retainer 144 and the retainer 44 may be omitted by giving the same number.

  In the circumferential direction of the retainer 144, the outer circumferential groove 44f and the end surface groove 44g are formed at the same position. Therefore, the outer peripheral groove 44f and the end face groove 44g are continuous. The lubricant existing outside the tapered roller bearing 2 is introduced into the tapered roller bearing 2 through the outer circumferential groove 44f and the end surface groove 44g. By using the retainer 144, the lubricant can be more easily introduced into the tapered roller bearing 2.

(Third embodiment)
The gear transmission of the third embodiment will be described with reference to FIGS. The gear transmission of this embodiment is different from the gear transmission 100 only in the shape of the retainer. Specifically, the retainer 244 of this embodiment is different from the retainer 44 in the shape of the outer peripheral groove formed on the case contact surface and the shape of the end surface groove formed on the carrier contact surface. Features common to the retainer 244 and the retainer 44 may be omitted from description because the same or the last two digits are given the same number.

  As shown in FIG. 9, a plurality of end surface grooves 244g are formed on the carrier contact surface 244e. When the end surface groove 244g is viewed from the bearing central axis 30 direction, the direction in which the end surface groove 244g extends has an angle with respect to the line connecting the outer peripheral surface (case contact surface 244d) of the cage 244 and the bearing central axis 30. (See FIG. 4 for comparison). The plurality of end face grooves 244g are inclined in the same direction. Further, as shown in FIG. 10, a plurality of outer peripheral grooves 244f are formed on the case contact surface 244d. When the outer circumferential groove 244f is viewed from a direction orthogonal to the bearing central axis 30, the direction in which the circumferential groove 244f extends has an angle with respect to the bearing central axis 30 (see FIG. 5 for comparison). The plurality of outer peripheral grooves 244f are inclined in the same direction. The end surface grooves 244g and the outer peripheral grooves 244f are alternately formed in the circumferential direction of the retainer 44. That is, the end surface groove 244g is formed between the adjacent outer peripheral grooves 244f, and the outer peripheral groove 244f is formed between the adjacent end surface grooves 244g.

  When the gear transmission 100 is driven, the retainer 244 rotates with respect to the carrier 10 and the case 4. When the end surface groove 244g is inclined, the lubricant can smoothly move in the end surface groove 244g along the end surface groove 244g as the retainer 244 rotates. Similarly, when the outer peripheral groove 244f is inclined, the lubricant can smoothly move in the outer peripheral groove 244f along the outer peripheral groove 244f as the retainer 244 rotates. Note that like the retainer 144, the end surface groove 244g and the outer peripheral groove 244f may be continuous.

(Fourth embodiment)
The gear transmission 300 will be described with reference to FIG. 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.

  In the gear transmission 300, inclined portions 346 are provided at the radial ends of the first plate 310a and the second plate 310c. The inclined portion 346 also serves as an inner race of the tapered roller bearing 302. That is, the inner race of the tapered roller bearing 302 is integrated with the carrier 310. Such a configuration can also be said that the inner race is attached to the carrier 310. A flange 310d is formed outside the inclined portion 346 of the first plate 310a. A flange 310e is formed outside the inclined portion 346 of the second plate 310c. The retainer 44 is the same as the retainer used in the gear transmission 100. Therefore, the retainer 44 contacts the flange 310 d and the flange 310 e in the direction of the axis 30, and contacts the case 4 in a direction orthogonal to the axis 30. Instead of the retainer 44, a retainer 144 or a retainer 244 can be used.

  In the above-described embodiment, an example in which the contact area between the retainer and the case is equal to the contact area between the retainer and the carrier has been described. However, for example, the contact area between the retainer and the case may be larger than the contact area between the retainer and the carrier. Conversely, the contact area between the retainer and the carrier may be larger than the contact area between the retainer and the case. Even in such a configuration, the friction on the outer peripheral surface of the roller can be reduced as compared with the case where the retainer contacts only the case or the carrier.

  In the above embodiment, the case where the case is stationary and the carrier rotates with respect to the case has been described. The technology disclosed in this specification can also be applied to a gear transmission in which the carrier is stationary and the case rotates with respect to the carrier. The technology disclosed in this specification can also be applied to a gear transmission in which a crankshaft is arranged coaxially with the axis of a carrier. Furthermore, the technology disclosed in this specification can also be applied to a gear transmission different from the eccentric oscillating type.

  In the fourth embodiment, the example in which the carrier also serves as the inner race has been described. The case may double as an outer race. Further, the carrier may double as an inner race, and the case may double as an outer race. What is important is that a tapered roller bearing is provided between the case and the carrier, and the rotating shaft of the roller of the tapered roller bearing is inclined with respect to the axis of the carrier. That is, the rib for restricting the movement is not formed.

  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.

2: Tapered roller bearing 4: Case 10: Carrier 40: Outer race 42: Roller (conical roller)
44: Retainer 46: Inner race 100: Gear transmission

Claims (3)

A gear transmission in which a carrier is supported by a case via a tapered roller bearing;
The tapered roller bearing is
An inner race attached to the carrier,
An outer race attached to the case;
A plurality of tapered rollers arranged between the inner race and the outer race;
A ring-shaped retainer that is arranged between the inner race and the outer race and maintains the interval between the adjacent tapered rollers;
The small diameter part of the tapered roller is located closer to the bearing center shaft than the large diameter part.
The outer peripheral surface of the inner race and the inner peripheral surface of the outer race are not provided with ribs that restrict the tapered rollers from moving away from the bearing center axis.
The retainer is made of a material having lower rigidity than the carrier and the case, and a carrier contact surface that contacts the carrier in the bearing central axis direction is provided at the end of the larger diameter, A gear transmission comprising a case contact surface that contacts the case in an orthogonal direction.   A gear transmission, wherein a groove is formed in at least one of the carrier contact surface and the case contact surface.   The gear transmission according to claim 1 or 2, wherein the retainer is made of resin.

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