JP6575847B2 - Planetary roller type power transmission device - Google Patents

Description

  The present invention relates to a planetary roller type power transmission device, and more specifically, a planetary roller type power transmission including an internal ring that urges the planetary roller radially inward by elastic deformation in the radial direction. It relates to the improvement of the apparatus.

  The planetary roller type power transmission device is a traction drive device that transmits power by pressing the planetary roller against the sun roller in the presence of lubricating oil. Compared with the planetary gear type power transmission device, vibration due to backlash And noise is low. For example, a planetary roller type power transmission device includes a sun roller, an internal ring, a planetary roller, and a carrier, and is used as a speed reducer that reduces the rotational output of an electric motor. The sun roller and the carrier are arranged coaxially. The planetary roller is a rolling element that contacts the outer peripheral surface of the sun roller and the inner peripheral surface of the internal ring. When the rotational force is input from the electric motor to the sun roller and is output through the carrier, the planetary roller revolves around the sun roller while rotating to output the rotational force.

  In the planetary roller type power transmission device described above, torque is transmitted via an oil film between the sun roller and the planetary roller and between the planetary roller and the internal ring. In this type of torque transmission, it is necessary to press the rolling members against each other with an appropriate force. For example, Patent Document 1 discloses a technique for generating a pressing force by configuring an internal ring with an elastic member that urges a planetary roller inward in the radial direction by elastically deforming in the radial direction. ing. In the planetary roller type power transmission device described in Patent Document 1, a plurality of planetary rollers 6 are arranged between the sun roller 3 and the elastic cylinder 4, and the elastic cylinder 4 presses the planetary roller 6 against the sun roller 3. . Since the elastic cylinder 4 urges the planetary roller 6 inward in the radial direction, the transmission torque can be increased without providing a separate urging member.

Japanese Utility Model Publication No. 57-163044

  If the thickness of the cylindrical internal ring is reduced, it becomes easier to bend, so that the area of the contact area with the planetary roller is increased, and the surface pressure acting on the contact area is locally reduced. For this reason, it can suppress that an internal ring is damaged by fatigue. However, in the conventional planetary roller type power transmission device as described above, if the internal ring is thinned, the phenomenon that the planetary roller is sunk into the internal ring occurs, and the contact area of the internal ring is locally deformed. I found out that For this reason, there is a possibility that the rolling resistance when the planetary roller rolls in the internal ring increases, and the transmission loss increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a planetary roller type power transmission device capable of suppressing the increase in transmission loss while improving the durability of the internal ring. To do.

  A planetary roller type power transmission device according to the present invention includes a solar roller rotatably supported by a casing around a main shaft, a cylindrical internal ring connected directly or indirectly to the casing, and the sun Two or more planetary rollers that contact the outer peripheral surface of the roller and the inner peripheral surface of the internal ring, and a carrier that is rotatably supported by the casing about the main shaft and that rotatably supports the planetary roller. . The planetary roller has a barrel shape in which the outer diameter of the central part is larger than that of the end part. The internal ring has an annular first convex portion projecting radially outward on an outer peripheral surface, and the first convex portion is in contact with the planetary roller on the inner peripheral surface of the internal ring and a shaft Arranged in overlapping directions.

  In the power transmission device, since the planetary roller has a barrel shape, the surface pressure between the planetary roller and the internal ring and the surface pressure between the planetary roller and the sun roller can be easily controlled. Further, since the internal ring biases the planetary roller toward the radially inward direction, the transmission torque can be increased without providing a biasing member separately.

  Further, an annular first convex portion is provided on the outer peripheral surface of the internal ring so as to overlap the contact area with the planetary roller on the inner peripheral surface of the internal ring and the axial position. If the thickness of the internal ring is reduced, it becomes easier to bend, so the area of the contact area with the planetary roller is expanded, the local surface pressure is reduced, and the internal ring is prevented from being damaged by fatigue. be able to.

  In the power transmission device, the rigidity of the contact portion can be increased by providing the first convex portion on the outer peripheral surface of the internal ring. For this reason, in the said power transmission device, even if it is a case where thickness is thinned and durability of an internal ring is improved, it can suppress that transmission loss increases. In other words, even when the internal ring is thinned, the phenomenon that the planetary roller is sunk into the internal ring and local contact deformation of the internal ring is prevented from being locally deformed. It is possible to suppress an increase in rolling resistance when rolling in the ring.

  In the planetary roller type power transmission device according to the present invention, since the rigidity of the contact portion is increased, it is possible to suppress the increase in transmission loss while improving the durability of the internal ring.

FIG. 1 is a cross-sectional view of a planetary roller power transmission device 1 according to an embodiment. FIG. 2 is a cross-sectional view showing a cut surface when the power transmission device 1 is cut along an AA cutting line. FIG. 3 is a cross-sectional view showing a cut surface when the power transmission device 1 is cut along a BB cutting line. FIG. 4 is an explanatory view schematically showing a part of the power transmission device 1. FIG. 5 is a view showing the roller facing portion 111 of the internal ring 11 in comparison with the comparative example. FIG. 6 is an explanatory diagram schematically showing the rolling mechanism of the power transmission device 1. FIG. 7 is an explanatory view schematically showing a phenomenon in which the planetary roller 12 sinks into the roller facing portion 111 of the internal ring 11.

  Embodiments of the present invention will be described below with reference to the drawings. In this specification, for the sake of convenience, the direction of the main shaft is described as a horizontal direction, but the posture of the power transmission device according to the present invention is not limited. In the present specification, the direction of the main axis is simply referred to as “axial direction”, and the radial direction and the circumferential direction around the main axis are simply referred to as “radial direction” and “circumferential direction”.

<Power transmission device 1>
FIG. 1 is a cross-sectional view showing a configuration example of a planetary roller type power transmission device 1 according to an embodiment of the present invention, and a cut surface when the power transmission device 1 is cut by a vertical surface including a main shaft J1. It is shown. In FIG. 1, the power transmission device 1 is drawn with the right side of the drawing as the input side and the left side as the output side. FIG. 2 is a cross-sectional view showing a cut surface when the power transmission device 1 of FIG. 1 is cut along an AA cutting line. FIG. 3 is a cross-sectional view showing a cut surface when the power transmission device 1 of FIG. 1 is cut along a BB cutting line.

  The main axis J <b> 1 is a straight line that indicates the rotation center common to the sun roller 101 and the carrier 141. The power transmission device 1 is a speed reducer that decelerates and outputs a rotational motion input from an electric motor (not shown), and includes an input rotator 10, an internal ring 11, a planetary roller 12, a casing 13, and an output rotation. The body 14 and the input side support member 15, the bearings 2 to 5, and the key member 6 are configured. For example, the bearings 2 to 5 are ball bearings in which two or more spherical rolling elements are disposed between the outer ring and the inner ring.

<Casing 13>
The casing 13 is a housing that houses a rolling member, which will be described later, and is fixed to a housing of an electric motor or the like. The casing 13 includes a bottomed cylindrical main body 131 having an opening on the input side, and a lid portion 132 disposed in the opening of the main body 131.

  The main body 131 includes a cylindrical portion 1311 extending in the axial direction and a bottom portion 1312 having a through hole 1313 for disposing the output rotating body 14. The lid part 132 has a through hole 1322 for arranging the input rotating body 10 and is attached to the cylindrical part 1311.

<Input Rotating Body 10>
The input rotator 10 is a member that is rotatably supported by the casing 13 around the main axis J1, and receives a predetermined rotational force from the electric motor. The input rotating body 10 includes an input shaft 100 connected to the shaft of the electric motor, a sun roller 101 that circumscribes the planetary roller 12, and a carrier support portion 102 that rotatably supports the carrier 141 via the bearing 4. Composed.

  The input shaft 100, the sun roller 101, and the carrier support portion 102 are integrally formed. The bearing 4 is disposed on the outer peripheral surface of the carrier support portion 102 by inserting the carrier support portion 102 into the inner ring.

<Sun Roller 101>
The sun roller 101 is a cylindrical rolling member having an outer peripheral surface extending in the axial direction. The sun roller 101 has an input shaft 100 coupled to an input side end portion and a carrier support portion 102 provided to an output side end portion. That is, the sun roller 101 is rotatably supported by the lid portion 132 of the casing 13 via the input shaft 100 and the bearing 2.

  For example, the bearing 2 is disposed on the outer peripheral surface of the sun roller 101 by being inserted into the inner ring after the bearing 2 is disposed in the through hole 1322 of the lid portion 132. Accordingly, the input rotating body 10 is supported by the bearings 2 and 4 with the rolling contact surface with the planetary roller 12 interposed therebetween.

<Internal ring 11>
The internal ring 11 is a cylindrical rolling member that inscribes the planetary roller 12, and its end is fixed to the casing 13. The internal ring 11 is composed of an elastic member that urges the planetary roller 12 radially inward by elastic deformation in the radial direction. For example, the internal ring 11 is formed of a flexible metal elastic body.

  For example, the internal ring 11 includes a roller facing portion 111 that faces the planetary roller 12 and an annular casing mounting portion 112 that is directly connected to the casing 13. The roller facing portion 111 and the casing attachment portion 112 are integrally formed.

The roller facing portion 111 is constituted by a cylindrical member having an inner peripheral surface extending in the axial direction, and a casing mounting portion 112 is provided at an end portion on the input side. The casing attachment part 112 is arrange | positioned coaxially with the main axis | shaft J1. The casing attachment portion 112 is disposed with the end surface on the input side facing the lid portion 132 of the casing 13, and has a key hole that accommodates the distal end portion of the pin-shaped key member 6 that penetrates the lid portion 132 in the axial direction. . That is, the casing mounting portion 112 is restricted from moving in the circumferential direction and the radial direction by inserting the key member 6 into the key hole. The internal ring 11 is fixed to the lid portion 132 using two or more key members 6.

<Planetary roller 12>
The planetary roller 12 is a rolling member that comes into contact with the outer peripheral surface of the sun roller 101 and the inner peripheral surface of the internal ring 11, and has a barrel shape in which the outer diameter of the central portion is larger than the end portion. The planetary roller 12 is rotatably supported by a carrier pin 122 via a needle bearing 121.

  The carrier pin 122 is a shaft member for the planetary roller and is held by the carrier 141. The carrier pin 122 has an output side end accommodated in the carrier 141, the input side end protrudes from the input side end surface of the planetary roller 12, and is brought into contact with the input side support member 15. The needle bearing 121 is a roller bearing composed of two or more cylindrical rolling elements extending in the axial direction, and is disposed between the outer peripheral surface of the carrier pin 122 and the inner peripheral surface of the planetary roller 12.

<Output rotating body 14>
The output rotator 14 is a member that is supported by the casing 13 so as to be rotatable about the main shaft J1, and outputs a rotational force to a predetermined load. The output rotating body 14 includes an output shaft 140 connected to a load and a carrier 141 that rotatably supports two or more planetary rollers 12. The output shaft 140 and the carrier 141 are integrally formed.

  The output shaft 140 is a shaft member connected to the output side end of the carrier 141. The outer diameter of the output shaft 140 is larger than that of the input shaft 100, and the output shaft 140 rotates at a low speed relative to the casing 13 as compared with the input shaft 100 due to the rotational force of the electric motor.

<Carrier 141>
The carrier 141 is a support member that supports the planetary roller 12 via the carrier pin 122, and is arranged coaxially with the sun roller 101. The carrier 141 is rotatably supported by the bottom portion 1312 of the casing 13 via the bearing 5, and is rotatably supported by the carrier support portion 102 of the input rotating body 10 via the bearing 4.

  For example, the bearing 5 is disposed in the through hole 1313 of the bottom portion 1312 and then disposed on the outer peripheral surface of the output side end portion by inserting the output side end portion of the carrier 141 into the inner ring. The bearing 4 is disposed in a bearing receiving hole provided in the carrier 141.

  The input side support member 15 is an annular member that supports the carrier pin 122, is arranged coaxially with the sun roller 101, and is rotatably supported by the lid portion 132 of the casing 13 via the bearing 3. The input side support member 15 is connected to the carrier 141 by two or more connection members 151 extending in the axial direction. For example, the bearing 3 is arranged on the outer peripheral surface of the boss portion 1321 by being arranged inside the input side support member 15 and then inserting the boss portion 1321 of the lid portion 132 into the inner ring.

  In the illustrated power transmission device 1, three planetary rollers 12 are arranged at equal intervals in the circumferential direction. Each planetary roller 12 is accommodated in a roller facing portion 111 of the internal ring 11 in a state of circumscribing the sun roller 101. Further, the internal ring 11, the carrier 141, and the input side support member 15 are disposed in the cylindrical portion 1311 of the casing 13.

  FIG. 4 is an explanatory view schematically showing a part of the power transmission device 1 of FIG. 1, in which a rolling mechanism constituted by the sun roller 101, the roller facing portion 111 of the internal ring 11, and the planetary roller 12. It is shown. In this figure, the shape of the planetary roller 12 and the inclination of the carrier pin 122 are exaggerated.

  FIG. 5 is a view showing the roller facing portion 111 of the internal ring 11 of FIG. 4 in comparison with a comparative example, in which a first convex portion 1111 and second convex portions 1112 and 1113 are shown. (A) in the figure shows the case of the power transmission device 1 according to the present invention, and (b) shows a comparative example.

  The planetary roller 12 is supported by the carrier pin 122 so as to be rotatable about the planetary rotation axis J2. The planetary rotation axis J2 is a straight line indicating the rotation center of the planetary roller 12. Since the planetary roller 12 has a barrel shape, the ridge line extending along the planetary rotation axis J2 on the outer peripheral surface has an arc shape.

  Further, the carrier pin 122 is arranged to be inclined with respect to the sun roller 101. For this reason, the contact region C1 between the planetary roller 12 and the roller facing portion 111 of the internal ring 11 and the contact region C2 between the planetary roller 12 and the sun roller 101 are shifted in the axial direction by a predetermined distance. . The inclination angle θ of the planetary rotation axis J2 with respect to the main axis J1 is common to the three planetary rollers 12.

  In the illustrated power transmission device 1, regarding the radial distance from the sun roller 101, the input side end of the carrier pin 122 is disposed farther than the output side end. For this reason, the contact area C1 is formed on the input side with respect to the contact area C2. The contact area C <b> 1 is formed at a position farthest from the sun roller 101 in the planetary roller 12.

  Since the planetary roller 12 has a barrel shape, the axial positions of the contact portions C1 and C2 and the surface pressure acting on the contact portions C1 and C2 can be easily controlled as compared with the case where the planetary roller 12 has a cylindrical shape. The surface pressure referred to here is a so-called Hertz surface pressure, and is a normal direction stress acting on the contact surface. The roller facing portion 111 of the internal ring 11 urges the planetary roller 12 radially inward by elastically deforming in the radial direction. For this reason, in the power transmission device 1, the transmission torque can be increased without separately providing a biasing member.

  In this power transmission device 1, the inner diameter of the roller facing portion 111 is substantially constant in the axial direction, and the inner peripheral surface of the roller facing portion 111 is a cylindrical surface. Convex portions 1111 and second convex portions 1112 and 1113 are provided. For example, the first convex portion 1111 and the second convex portions 1112 and 1113 are both narrower in the axial direction than the axial width of the planetary roller 12. By providing such a convex portion on the internal ring 11, the rigidity of the internal ring 11 can be locally increased in a range narrower than a region facing the planetary roller 12 in the radial direction.

  Each of the first convex portion 1111 and the second convex portions 1112 and 1113 is an annular projecting portion that projects radially outward, and is arranged with different positions in the axial direction. Further, the first convex portion 1111 and the second convex portions 1112 and 1113 both project outward in the radial direction from the outer peripheral surface of the thin portion of the roller facing portion 111, and in the circumferential direction along the outer peripheral surface. It is an extended shape.

  The first convex portion 1111 is disposed so that the position in the axial direction overlaps with the contact region C <b> 1 with the planetary roller 12 on the inner peripheral surface of the internal ring 11. That is, the 1st convex part 1111 is arrange | positioned in the position which overlaps with a part or all of contact region C1, if it sees from the radial direction outer side.

  For example, the first protrusion 1111 has an axial width W narrower than the contact area C1. As used herein, the width W is, for example, a portion in the circumferential direction that is thicker than the thin portion being a thick portion, and the radial height from the outer peripheral surface of the thin portion to the tip of the thick portion being H, It is the width of the thick part where the height is H / 2 or more, that is, the half width. If comprised in this way, since the 1st convex part 1111 can be arrange | positioned in the contact area C1, it is suitable for raising the rigidity of a contact part. The first protrusion 1111 may have an axial width W wider than the contact area C1.

  In the power transmission device 1 according to the present invention, the surface shape in the vicinity of the first convex portion 1111 is a smooth curved surface. In other words, the first convex portion 1111 has a diameter that is changed by a curve in which the inclination of the tangential axis with respect to the curve indicating the surface shape on the outer side in the radial direction continuously changes in a cross section when cut by an arbitrary plane including the main axis J1. An outer surface shape in the direction is formed.

  On the other hand, in the comparative example, at the boundary between the thin part and the thick part in the roller facing portion 111, the outer side in the radial direction is indicated by a polygonal line in which the inclination in the axial direction of the tangent to the curve indicating the surface shape on the radially outer side changes discontinuously. The surface shape is configured. In such a configuration in which the thickness of the roller facing portion 111 changes abruptly, stress concentration tends to occur during elastic deformation. On the other hand, in this Embodiment, it can suppress that stress concentrates on the 1st convex part 1111 vicinity at the time of the elastic deformation of the internal ring 11.

  Since the contact region C1 is formed on the input side in the axial direction with respect to the contact region C2, the first convex portion 1111 is input in the axial direction between the second convex portion 1112 and the second convex portion 1113. It is biased to the side. That is, the 1st convex part 1111 is arrange | positioned in the axial direction from the center of the area | region facing the planetary roller 12 in the internal ring 11 in radial direction.

  The 2nd convex parts 1112 and 1113 are each arrange | positioned in the position of the axial direction facing the both ends of the planetary roller 12. FIG. If it demonstrates concretely, the 2nd convex part 1112 will be arrange | positioned so that the edge part of the output side of the planetary roller 12 may overlap the position of an axial direction. That is, the second convex portion 1112 is arranged with its axial position overlapped with the region on the inner peripheral surface of the internal ring 11 that is radially opposed to the output side end portion of the planetary roller 12, and the radial direction When viewed from the outside, the position overlaps the output side end of the planetary roller 12.

  On the other hand, the 2nd convex part 1113 is arrange | positioned so that the edge part of the input side of the planetary roller 12 may overlap the position of an axial direction. That is, the second convex portion 1113 is arranged with its axial position overlapping with the region on the inner peripheral surface of the internal ring 11 that is radially opposed to the input side end of the planetary roller 12, and the radial direction When viewed from the outside, the position overlaps the input side end of the planetary roller 12.

  In the power transmission device 1 according to the present embodiment, the surface shape in the vicinity of the second convex portions 1112 and 1113 is configured by a smooth curved surface. That is, the second convex portions 1112 and 1113 continuously change in the inclination in the axial direction of the tangent to the curve indicating the surface shape on the radially outer side in the cross section when cut by an arbitrary plane including the main axis J1. The curved outer surface shape is formed by the curved line.

  The roller facing portion 111 of the internal ring 11 has a shape in which a gap is generated between the inner peripheral surface of the cylindrical portion 1311 of the casing 13 and the first convex portion 1111 on the radially outer side than the planetary roller 12. A distance D between the inner peripheral surface of the cylindrical portion 1311 and the first convex portion 1111 is minimized when the planetary roller 12 passes immediately below the roller facing portion 111.

  The first convex portion 1111 and the second convex portions 1112 and 1113 are formed integrally with the thin portion of the roller facing portion 111. For example, the roller facing portion 111 having the first convex portion 1111 and the second convex portions 1112 and 1113 is formed by cutting the outer peripheral surface of the cylindrical body by cutting. The internal ring 11 has a configuration in which the first convex portion 1111, the second convex portion 1112 or 1113 are formed by a member different from the thin portion of the roller facing portion 111 and joined to the outer peripheral surface of the thin portion. There may be.

  In this power transmission device 1, since the contact areas C1 and C2 are displaced in the axial direction, the pressing force F1 applied to the planetary roller 12 from the roller facing portion 111 of the internal ring 11 and the sun roller 101 to the planetary roller The pressing force F2 applied to 12 is in a couple relationship. The pressing forces F1 and F2 are both pressing forces acting on the contact surface. The planetary roller 12 generates a moment of force in a direction perpendicular to the paper surface in accordance with the magnitudes of the pressing forces F1 and F2 and the distance between the action lines of the pressing forces F1 and F2. For this reason, since backlash or play between the carrier pin 122 and the planetary roller 12 is offset, backlash can be reduced.

  FIG. 6 is an explanatory view schematically showing the rolling mechanism of the power transmission device 1 of FIG. 1, and shows a cut surface when the rolling mechanism is cut by a vertical plane perpendicular to the main axis J1. FIG. 7 is an explanatory view schematically showing a phenomenon in which the planetary roller 12 of FIG. 6 sinks into the roller facing portion 111 of the internal ring 11.

  Each of the three planetary rollers 12 circumscribes the sun roller 101 and inscribed in the roller facing portion 111 of the internal ring 11. Further, the roller facing portion 111 of the internal ring 11 is constituted by a member having a smaller inner peripheral surface diameter than the circumscribed circle circumscribing the three planetary rollers 12.

  When three planetary rollers 12 are arranged in such a roller facing portion 111, the roller facing portion 111 is elastically deformed in the radial direction, and an internal tension is generated at a contact portion with the planetary roller 12. The planetary roller 12 is urged radially inward by the resultant force. The aforementioned pressing force F1 is a resultant force of internal tension. The upper limit value of the torque that can be transmitted is proportional to the magnitudes of the pressing forces F1 and F2.

  For example, when the sun roller 101 rotates clockwise as viewed from the input side, each planetary roller 12 revolves clockwise around the sun roller 101 while rotating in the opposite direction to the clockwise direction. Each portion in the circumferential direction of the roller facing portion 111 is displaced to the outermost side in the radial direction when the planetary roller 12 passes directly below the inner peripheral surface, and the planetary roller 12 passes directly below the inner peripheral surface. In the middle of the period until the next planetary roller 12 passes.

  In the rolling contact between the roller facing portion 111 and the planetary roller 12, the contact portion is locally elastically deformed by the contact stress acting on the contact surface. Elastic deformation of the contact portion in the roller facing portion 111 is repeated each time the planetary roller 12 passes. If the local contact stress is lowered, fatigue at the contact site due to repeated elastic deformation can be reduced.

  The roller facing portion 111 of the internal ring 11 is easily bent in the radial direction if the thickness is reduced. Since the roller facing portion 111 bends in the radial direction, the area of the contact area with the planetary roller 12 is expanded in the circumferential direction, so that the local surface pressure acting on the contact surface is reduced. Therefore, by making the roller facing portion 111 thinner, it is possible to suppress the internal ring 11 from being damaged due to fatigue.

  However, if the roller facing portion 111 of the internal ring 11 is made thin, the phenomenon that the planetary roller 12 is sunk into the roller facing portion 111 (see FIG. 7) occurs, and the vicinity of the contact portion of the roller facing portion 111 is locally deformed. I found out that For this reason, the rolling resistance when the planetary roller 12 rolls in the roller facing part 111 increases.

  Therefore, in the power transmission device 1 according to the present embodiment, by providing the first convex portion 1111 on the outer peripheral surface of the roller facing portion 111, the rigidity of the contact portion is increased, so that the constriction of the roller facing portion 111 is reduced. For this reason, in the power transmission device 1, even when the thickness is reduced to improve the durability of the internal ring 11, it is possible to suppress an increase in transmission loss.

  Each part which comprises the power transmission device 1 by this Embodiment is as above-mentioned. Below, the relationship between these components and the effect produced by it are demonstrated in detail.

(1) Improvement of durability and reduction of transmission loss In the power transmission device 1 according to the present embodiment, the area of the contact region C1 with the planetary roller 12 is increased by making the roller facing portion 111 of the internal ring 11 thinner. And since local surface pressure becomes low, it can suppress that the internal ring 11 is damaged by fatigue. Further, by providing the first convex portion 1111 on the outer peripheral surface of the roller facing portion 111, the rigidity of the contact portion is increased, so that the internal ring 11 is reduced. For this reason, in the power transmission device 1, even when the thickness is reduced to improve the durability of the internal ring 11, an increase in transmission loss can be suppressed.

(2) Avoidance per edge In the power transmission device 1 according to the present embodiment, the second convex portions 1112 and 1113 are provided at the axial positions facing the both ends of the planetary roller 12, respectively. Since the rigidity of the portions facing both ends of the planetary roller 12 is improved, the phenomenon that the internal ring 11 contacts the end of the planetary roller 12, that is, the so-called edge contact can be suppressed.

(3) Dispersion of stress In the power transmission device 1 according to the present embodiment, the surface shapes of the first convex portion 1111, the second convex portions 1112, and 1113 are each composed of a smooth curved surface. When the roller facing portion 111 is elastically deformed, it is possible to suppress the local concentration of stress around these thick portions.

(4) Collision Prevention In the power transmission device 1 according to the present embodiment, the outer peripheral surface of the cylindrical portion 1311 of the casing 13 and the first convex portion 1111 of the internal ring 11 are radially outward from the planetary roller 12. A gap is formed between them. For this reason, in the power transmission device 1, when the roller facing portion 111 of the internal ring 11 vibrates in the radial direction as the planetary roller 12 revolves with respect to the sun roller 101, the internal ring 11 is in the casing 13. Can be prevented from colliding.

  In this embodiment, three convex portions (the first convex portion 1111 and the second convex portions 1112 and 1113) are provided on the roller facing portion 111 of the internal ring 11 with different positions in the axial direction. Although an example has been described, the present invention does not limit the configuration of the internal ring 11 to this. For example, the power transmission device 1 may have a configuration in which four or more convex portions having different axial positions are provided on the outer peripheral surface of the roller facing portion 111.

  In the present embodiment, an example in which the internal ring 11 is directly connected to the casing 13 has been described. However, in the present invention, power transmission in which the internal ring 11 is indirectly connected to the casing 13 is described. The present invention can also be applied to the device 1. For example, the power transmission device 1 may be configured to connect the internal ring 11 to the casing 13 via a bearing in which the outer ring is fixed to the casing 13.

  Further, in the present embodiment, an example in which the end portion on the input side in the axial direction of the internal ring 11 is connected to the casing 13 has been described. However, in the present invention, the fixed end of the internal ring 11 is used as the casing 13. However, the method of connecting to is not limited to this. For example, the power transmission device 1 may be configured such that the axial end of the internal ring 11 on the output side is connected to the casing 13.

  In this embodiment, an example in which the roller facing portion 111 of the internal ring 11 has a cylindrical shape has been described, but the present invention does not limit the shape of the roller facing portion 111 to this. For example, the roller facing portion 111 has a radially inner surface shape constituted by a curve having a smaller curvature than the ridgeline of the outer peripheral surface of the planetary roller 12 in a cross section when cut by an arbitrary plane including the main shaft J1. The power transmission device 1 may have such a configuration.

  In the present embodiment, the casing 13 is fixed to the housing of the electric motor, etc., and the rotational force of the electric motor is transmitted to the sun roller 101 via the input shaft 100, and the rotational force from the output shaft 140 via the carrier 141. However, the present invention is not limited to this usage pattern of the power transmission device 1.

  For example, among the three members of the casing 13, the sun roller 101, and the carrier 141, any one member can be fixed to the housing of the electric motor, and one of the other members can be used as an input and the other as an output. . That is, the present invention can also be applied to the power transmission device 1 in which the internal ring 11 connected to the casing 13 rotates relative to the housing of the electric motor or the like.

  Further, the power transmission device 1 may be configured such that the casing 13 is formed integrally with a housing of an electric motor or a casing of another power transmission device such as a transmission or a gearbox. Alternatively, the power transmission device 1 may be configured to use a casing common to the electric motor or another power transmission device as the casing 13.

DESCRIPTION OF SYMBOLS 1 Power transmission device 2-5 Bearing 6 Key member 10 Input rotary body 100 Input shaft 101 Sun roller 102 Carrier support part 11 Internal ring 111 Roller opposing part 1111 1st convex part 1112 and 1113 2nd convex part 112 Casing attachment part 12 Planetary roller 121 Needle bearing 122 Carrier pin 13 Casing 131 Main body portion 1311 Cylindrical portion 1312 Bottom portion 132 Cover portion 14 Output rotating body 140 Output shaft 141 Carrier 15 Input side support member 151 Connecting member C1, C2 Contact area F1, F2 Pressing force J1 Main shaft J2 planetary rotation axis

Claims (4)

A sun roller rotatably supported around the main shaft by a casing;
A cylindrical internal ring connected directly or indirectly to the casing;
Two or more planetary rollers in contact with the outer peripheral surface of the sun roller and the inner peripheral surface of the internal ring;
A carrier that is rotatably supported by the casing about the main shaft, and that supports the planetary roller rotatably;
The planetary roller has a barrel shape in which the outer diameter of the central part is larger than the end part,
The internal ring has an annular first convex portion projecting radially outward on an outer peripheral surface, and the first convex portion is in contact with the planetary roller on the inner peripheral surface of the internal ring and a shaft It is arranged by overlapping the position of the direction,
The internal ring further has an annular second convex portion projecting radially outward on the outer peripheral surface, and the second convex portion is arranged so that the end of the planetary roller overlaps the axial position. A planetary roller type power transmission device. 2. The planetary roller power transmission device according to claim 1 , wherein the second convex portions are respectively disposed at positions in an axial direction facing both end portions of the planetary roller. In the cross section when the second convex portion is cut by an arbitrary plane including the main axis, the surface shape is determined by a curve in which an inclination with respect to the axial direction of a tangent to a curve indicating the surface shape on the radially outer side continuously changes. The planetary roller type power transmission device according to claim 1 or 2 , wherein The internal ring in the radially outward than the planetary rollers, according to claim 1 to 3, characterized in that it has a shape void occurs between the first protrusion and the inner peripheral surface of the casing The planetary roller type power transmission device according to any one of the above.

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