Friction transmission device

Abstract

To provide a friction electric motor device which can use a range of speed ratio more effectively.SOLUTION: A friction transmission device 100 includes an input bearing ring 14, a planetary roller 20 arranged around a rotation axis La of the input bearing ring 14 and in contact with the input bearing ring 14, an output bearing ring 30 in contact with the planetary roller 20 and connected to an output member 32, and first and a second support bearing rings 26, 28 in contact with the planetary roller 20. The friction transmission device has a speed ratio change mechanism 6 which changes a relative position of two outer bearing rings to change a speed ratio. The speed ratio changed by the speed ratio change mechanism 6 is varied in a maximum quantity of an absolute value of the speed ratio in between a plus side and a minus side. A first contact face 20d and a second contact face 20c which are in contact with two outer bearing rings of the planetary roller 20 are configured to be different from each other in their shapes.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a friction transmission. [Background technology]

[0002] A continuously variable transmission capable of an infinitely large gear ratio, called an IVT (Infinitely Variable Transmission), is known. In Patent Document 1, the present applicant disclosed a technology for a friction transmission device including an input raceway, planetary rolling elements, and an output raceway. In this device, the planetary rolling elements are disposed around the rotation axis of the input raceway and contact the input raceway, and the output raceway is in contact with the planetary rolling elements and connected to the output shaft. This device also has a plurality of support raceways in contact with the planetary rolling elements, and changes the speed of the rotation input to the input raceway and outputs it from the output shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 182001 Summary of the Invention [Problem to be solved by the invention]

[0004] Friction transmissions are expected to be used in many applications, such as robots and self-propelled vehicles. Friction transmissions can change the speed ratio of the output rotation from the reverse rotation side to the forward rotation side by changing the posture of the components using mechanical input for speed ratio control. However, in conventional devices, the speed change characteristics are symmetrical between the forward rotation side and the reverse rotation side, and there is a problem that the range of the speed ratio cannot be used more effectively depending on the application.

[0005] SUMMARY OF THE PRESENT INVETION In view of the above problems, an object of the present invention is to provide a friction transmission device which can more effectively utilize the range of speed ratios. [Means for solving the problem]

[0006] In order to solve the above problems, a friction transmission device according to one embodiment of the present invention is a friction transmission device including an input raceway, planetary rolling elements arranged around the rotation axis of the input raceway and in contact with the input raceway, an output raceway in contact with the planetary rolling elements and connected to an output member, and first and second support raceways in contact with the planetary rolling elements, and further including a speed ratio change mechanism that changes the speed ratio by changing the relative positions of two inner driving rings among the input raceway, output raceway, first support raceway, and second support raceway that are located inside the planetary rolling elements, and two outer raceways that are located outside the planetary rolling elements. The speed ratio changed by the speed ratio change mechanism is configured such that the maximum absolute value of the speed ratio on the plus side, where the output rotation is in the same direction as the input rotation, is different from the maximum absolute value of the speed ratio on the minus side, where the output rotation is in the opposite direction to the input rotation, and the shapes of the first and second contact surfaces that come into contact with the two outer raceways of the planetary rolling elements are different from each other.

[0007] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0008] According to the present invention, it is possible to provide a friction motor-driven device that can use the range of speed change ratios more effectively. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view showing an example of a friction transmission device according to an embodiment; [Diagram 2] 2 is a cross-sectional view showing a cross section of the friction transmission device taken along line AA in FIG. 1. [Diagram 3] 2 is a perspective view showing an input race of the friction transmission of FIG. 1. [Figure 4] 2 is a perspective view showing a first support bearing ring of the friction transmission of FIG. 1. [Diagram 5] 2 is a perspective view showing a planetary rolling element of the friction transmission of FIG. 1. [Figure 6] 2 is a perspective view showing a cage of the friction transmission of FIG. 1. [Figure 7] 2 is a perspective view showing a planetary rolling element unit of the friction transmission of FIG. 1. [Figure 8] 2 is a perspective view showing a second support ring of the friction transmission of FIG. 1. FIG. [Figure 9] 2 is a perspective view showing an output race of the friction transmission device of FIG. 1. [Figure 10] 2 is a perspective view showing an output member of the friction transmission device of FIG. 1. [Figure 11] 2 is a perspective view showing a pressing cam of the friction transmission device of FIG. 1. [Figure 12] 2 is a perspective view showing a roller cage of the friction transmission of FIG. 1. [Figure 13] FIG. 2 is a perspective view showing a cover of the friction transmission device of FIG. [Figure 14] 14 is a perspective view showing a state in which a predetermined member is attached to the cover of FIG. 13. FIG. [Figure 15] 2 is a schematic diagram illustrating the operation of a pressing force imparting mechanism of the friction transmission device of FIG. 1. [Figure 16] 2 is a perspective view showing a speed ratio change mechanism of the friction transmission of FIG. 1. [Figure 17] 1 is a cross-sectional view showing a first configuration example of a friction transmission according to an embodiment. [Figure 18] FIG. 4 is a cross-sectional view showing a second configuration example of the friction transmission device of the embodiment. [Figure 19] FIG. 4 is a cross-sectional view showing a third configuration example of the friction transmission device according to the embodiment. [Figure 20] FIG. 11 is a cross-sectional view showing a fourth configuration example of the friction transmission device according to the embodiment. [Figure 21] FIG. 11 is a cross-sectional view showing a fifth configuration example of a friction transmission device according to an embodiment. [Figure 22] FIG. 11 is a cross-sectional view showing a sixth configuration example of a friction transmission device according to an embodiment. [Figure 23] FIG. 2 is a cross-sectional view showing the configuration of a friction transmission device according to a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modified examples, the same or equivalent components and members are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0011] In addition, terms including ordinal numbers such as first, second, etc. are used to describe various components, but these terms are used only for the purpose of distinguishing one component from another component, and the components are not limited by these terms.

[0012] [Embodiment] First, the overall configuration of a friction transmission 100 according to an embodiment of the present disclosure will be described. FIG. 1 is a perspective view showing an example of a friction transmission 100 according to an embodiment. FIG. 2 is a cross-sectional view showing a longitudinal section of the friction transmission 100 taken along line AA. The friction transmission 100 has a casing 37 that encloses an internal mechanism, an input shaft 64, an output member 32, and an attachment member 38. The attachment member 38 is a brim-shaped member provided on the outer periphery of the casing 37 in order to attach the friction transmission 100 to an external device (not shown). FIG. 2 shows a state in which the attachment member 38 has been removed.

[0013] The friction transmission device 100 is configured such that the rotation input to the input shaft 64 rotates the input raceway, thereby causing the planetary rolling elements to rotate and revolve about their axes, and the rotational components thus generated are output to a driven device (not shown) from the output member 32 connected to the output raceway.

[0014] The friction transmission device 100 mainly includes an input mechanism 2, a transmission mechanism 3, an output mechanism 5, a pressing force imparting mechanism 7, and a speed ratio change mechanism 6. The input mechanism 2 is a mechanism that transmits the rotation input from a prime mover (not shown) to an input raceway 14. The transmission mechanism 3 is a mechanism that changes the speed of the rotation transmitted to the input raceway 14 and transmits it to an output raceway 30. The output mechanism 5 is a mechanism that outputs the rotation transmitted to the output raceway 30 from an output member 32 to a driven device. The pressing force imparting mechanism 7 imparts an axial pressing force to the transmission mechanism 3. The speed ratio change mechanism 6 is a mechanism that changes the relative positions of the raceways of the transmission mechanism 3 to control the gear ratio.

[0015] The input mechanism 2 will be described with reference to Fig. 2. The input mechanism 2 according to the embodiment includes an input shaft 64, a ball spline nut 65, an input bearing 66, a cover 67, a first oil seal S1, a shaft 68, a shaft cap 69, an input race 14, a sleeve 15, a first support race 26, and a bearing 27 for the first race.

[0016] Hereinafter, the direction along the rotation axis La of the input race 14 will be referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the rotation axis La will be referred to as the "circumferential direction" and the "radial direction," respectively. For convenience, one side in the axial direction (the right side in the drawing) will be referred to as the "input side," and the other side (the left side in the drawing) will be referred to as the "anti-input side."

[0017] Unless otherwise specified, the circular parts surrounding the rotation axis La of each member of the friction transmission 100 are formed around the rotation axis La. The centers of these circular parts may be shifted from the rotation axis La within a margin of error.

[0018] The input shaft 64 is an input section to which rotation from a prime mover is input. The prime mover in this embodiment is the motor 50, and the input shaft 64 is connected to a motor shaft 51 to which the rotation of the motor 50 is output. The ball spline nut 65 transmits the rotation of the input shaft 64 to a shaft 68, and supports the shaft 68 so that it can move in the axial direction. The input shaft 64 has an outer cylinder that houses the ball spline nut 65. The ball spline nut 65 is key-connected to the input shaft 64 by a key 65k, and rotates integrally with the input shaft 64. The shaft 68 is axially movable relative to the ball spline nut 65, and rotates integrally with the ball spline nut 65.

[0019] The cover 67 is a hollow disk-shaped member that covers the input side of the friction transmission 100, and has a hollow portion 67c that surrounds the rotation axis La. The cover 67 is fixed to the input side of the casing 37 by a plurality of bolts B1. The input bearing 66 is disposed between the hollow portion 67c and the ball spline nut 65, and supports the ball spline nut 65 and the input shaft 64 so that they can rotate relative to each other. The outer ring of the input bearing 66 is supported by the hollow portion 67c, and the inner ring supports the input shaft 64. The input bearing 66 in this example is a ball bearing. The first oil seal S1 is disposed on the input side of the input bearing 66 in the hollow portion 67c, and seals the input bearing 66.

[0020] The shaft 68 is a rod-shaped shaft extending in the axial direction, and has an axial groove (not shown) through which balls pass. The input side of the shaft 68 is accommodated in the ball spline nut 65, and the tip of the shaft 68 extends further toward the anti-input side than the planetary rolling elements 20. The shaft cap 69 is a member that regulates the positional relationship between the shaft 68 and the first support raceway 26. The shaft cap 69 has a cup shape that is composed of a disk portion 69b and a cylindrical portion 69c that extends from the outer periphery of the disk portion 69b toward the input side. The tip of the shaft 68 is inserted into the cylindrical portion 69c, and is fixed to the disk portion 69b by a bolt B3 that passes through the disk portion 69b.

[0021] The input raceway 14 will be described with reference to Fig. 3. In Figs. 3 to 12 and 16, (A) shows a view from diagonally above the non-input side, and (B) shows a view from diagonally above the input side. Fig. 3 is a perspective view showing the input raceway 14. The input raceway 14 in the example of Fig. 3 is formed integrally with a sleeve 15.

[0022] The sleeve 15 is a hollow cylindrical member fixed to the outer periphery of the shaft 68 by interference fit or the like, and has a first cylindrical portion 15b and a second cylindrical portion 15c from the input side toward the non-input side. The first cylindrical portion 15b is surrounded by the control portion bearing 63 and rotatably supported by the control portion bearing 63. The second cylindrical portion 15c is continuous with the first cylindrical portion 15b at a portion having a larger diameter than the first cylindrical portion 15b. A step portion 15d is formed at the boundary between the first cylindrical portion 15b and the second cylindrical portion 15c. A circumferential groove 15g is provided around the first cylindrical portion 15b, in which a retaining ring W1 is attached to regulate the positional relationship with the control portion bearing 63.

[0023] The input race 14 is a hollow cylindrical member fixed to the outer periphery of the shaft 68, has a larger diameter than the second cylindrical portion 15c, and is continuous with the second cylindrical portion 15c. The input race 14 is a hole into which the shaft 68 is fitted, and has a hollow portion 14e penetrating from the non-input side of the input race 14 to the input side of the sleeve 15. A rolling surface 14h that contacts the planetary rolling element 20 is provided on the outer periphery of the input race 14. The input race 14 has a bearing receiving portion 14j for receiving a part of the input side of the first race bearing 27. The bearing receiving portion 14j in this example is a circular recess recessed from the end face of the non-input side of the input race 14 to the input side.

[0024] The input raceway 14 is a member for supporting the planetary rolling elements 20 in a predetermined position and transmitting rotation to the planetary rolling elements 20. The rolling surface 14h is a surface on which the planetary rolling elements 20 roll, and is in point contact or surface contact with the planetary rolling elements 20. The rolling surface 14h may be inclined in the axial direction and the radial direction. The rolling surface 14h may include a tapered surface that reduces in diameter toward the input side. The rolling surface 14h may be a curved surface such as a flat surface or a concave surface, but in this example, it is a convex surface.

[0025] The first support race 26 will be described with reference to FIG. 4. FIG. 4 is a perspective view showing the first support race 26. The first support race 26 is a cylindrical member that fits around the outer periphery of the shaft 68 and is rotatably supported by the shaft 68, and is a hollow cylindrical member having approximately the same diameter as the input race 14. The first support race 26 has a through hole 26d that surrounds the shaft 68. A rolling surface 26h that contacts the planetary rolling element 20 is provided on the outer periphery of the first support race 26. The first support race 26 has a bearing accommodating portion 26j for accommodating a part of the anti-input side of the first race bearing 27. The bearing accommodating portion 26j in this example is a circular recess that is recessed from the input side end face of the first support race 26 to the anti-input side.

[0026] The first support raceway 26 is a member for supporting the planetary rolling element 20 in a predetermined position. The rolling surface 26h is a surface on which the planetary rolling element 20 rolls, and is in point contact or surface contact with the planetary rolling element 20. The rolling surface 26h may be inclined in the axial direction and the radial direction. The rolling surface 26h may include a tapered surface that reduces in diameter toward the non-input side. The rolling surface 26h may be a curved surface such as a flat surface or a concave surface, but is a convex surface in this example. The first support raceway 26 is freely rotatable with respect to the shaft 68 and the planetary rolling element 20, and may be referred to as an idle raceway.

[0027] The first bearing ring 27 is a thrust bearing that rotatably supports the first support bearing ring 26 relative to the input bearing ring 14. For example, the first bearing ring 27 can be composed of two rings facing each other in the axial direction and a number of spheres interposed between the two rings.

[0028] The transmission mechanism 3 will be described with reference to Fig. 2 and Fig. 5 to Fig. 9. The transmission mechanism 3 of the embodiment includes a plurality of planetary rolling elements 20, a cage 21, an input race 14, a first support race 26, a second support race 28, and an output race 30. The input race 14, the first support race 26, the second support race 28, and the output race 30 are collectively referred to as "races."

[0029] 5 is a perspective view showing the planetary rolling element 20. A plurality of planetary rolling elements 20 (for example, five) are arranged at a predetermined interval in the circumferential direction. The number of planetary rolling elements 20 is not particularly limited and may be less than or more than five, but is preferably 5 to 12. The planetary rolling element 20 has a contact surface 20a that contacts the rolling surface 14h of the input race 14, a contact surface 20b that contacts the rolling surface 26h of the first support race 26, a contact surface 20c that contacts the rolling surface 28h of the second support race 28, and a contact surface 20d that contacts the rolling surface 30h of the output race 30.

[0030] The rolling surfaces 14h, 26h, 28h, and 30h of the raceways are collectively referred to as the rolling surfaces of the raceways. The contact surfaces 20a, 20b, 20c, and 20d are collectively referred to as the contact surfaces of the planetary rolling elements. The contact surfaces 20a and 20b may be flat or convex, but in this example they are concave. The contact surfaces 20c and 20d may be flat or concave, but in this example they are convex.

[0031] The planetary rolling body 20 is regulated in its axial position, radial position and attitude by contacting the rolling surface of the raceway. The shape of the planetary rolling body 20 may be any shape as long as its attitude is determined by contacting the rolling surface of the raceway and it can roll while contacting the rolling surface of the raceway. As shown in FIG. 5, the planetary rolling body 20 of the embodiment is a rotating body obtained by rotating a trapezoid whose upper base and legs are curved around a predetermined axis. The predetermined axis is an axis parallel to the lower base of the trapezoid and spaced apart from the lower base on the opposite side to the upper base. In this specification, the circle formed by the intersection of a plane (hereinafter referred to as the "equatorial plane") that passes through the center of the upper base of the trapezoid and is perpendicular to the rotation axis Lb of the planetary rolling body 20 and the outer circumferential surface of the planetary rolling body 20 is referred to as the "equator". In this example, the equator 20e is a circle formed by the intersection of the equatorial plane and the outer circumferential surface of the planetary rolling body 20.

[0032] The inclination of the rotation axis Lb of the planetary rolling element 20 with respect to the rotation axis La varies depending on the relative position of the rolling surface of the raceway. That is, the rotation axis Lb may be parallel to the rotation axis La or may be inclined with respect to the rotation axis La.

[0033] 6 is a perspective view showing the retainer 21. The friction transmission 100 of the embodiment includes the retainer 21 for retaining the multiple planetary rolling elements 20 at desired positions. The retainer 21 restricts the circumferential movement of the multiple planetary rolling elements 20. The retainer 21 retains the multiple planetary rolling elements 20 at predetermined intervals in the circumferential direction so as to prevent the planetary rolling elements 20 from contacting each other. The retainer 21 has two ring portions 22 and multiple (e.g., five) pillar portions 23. The ring portions 22 and the pillar portions 23 of the retainer 21 can be integrally formed from resin or metal.

[0034] The two ring portions 22 are arranged axially apart, sandwiching the planetary rolling element 20 therebetween. The ring portion 22 is a hollow annular portion having a central hole 22c. The multiple pillar portions 23 are strip-shaped members extending in the axial direction, and are arranged between the multiple planetary rolling elements 20 at predetermined intervals in the circumferential direction. One end of the pillar portion 23 is fixed to the outer periphery of one ring portion 22, and the other end is fixed to the outer periphery of the other ring portion 22. In other words, the pillar portion 23 is bridged between the two ring portions 22. A pocket 24 for holding the planetary rolling element 20 is formed between two adjacent pillar portions 23.

[0035] Fig. 7 is a perspective view showing the planetary rolling element unit 4. As shown in Fig. 7, a plurality of planetary rolling elements 20 are incorporated into each pocket 24 of the cage 21 to form the planetary rolling element unit 4. The planetary rolling elements 20 are held in the pockets 24 so as to be rotatable.

[0036] FIG. 8 is a perspective view showing the second support raceway 28. The second support raceway 28 has a ring shape that surrounds the sleeve 15 and the planetary rolling element 20. The second support raceway 28 has a rolling surface 28h on the opposite input side and a cam surface 28p on the input side. The rolling surface 28h is a surface on which the planetary rolling element 20 rolls, and is in point contact or surface contact with the planetary rolling element 20. The rolling surface 28h is inclined in the axial direction and the radial direction. The rolling surface 28h includes a tapered surface that reduces in diameter toward the input side. The rolling surface 28h in this example is a conical surface composed of a flat surface. Since the conical surface is a concave surface, the contact surface 20c, which is a convex surface, and the rolling surface 28h are in uneven contact.

[0037] The cam surface 28p has a plurality of (for example, six) concave cam grooves 28j each consisting of a first inclined surface 28f and a second inclined surface 28g. The cam grooves 28j have a V-shape when viewed in the radial direction from the outer diameter side. The multiple cam grooves 28j are arranged at predetermined intervals in the circumferential direction and are connected to each other by a connection surface 28e. The connection surface 28e can be formed parallel to a plane perpendicular to the rotation axis La. The first inclined surface 28f is inclined with respect to the plane perpendicular to the rotation axis La. The second inclined surface 28g is inclined in the opposite direction to the first inclined surface 28f with respect to the plane perpendicular to the rotation axis La.

[0038] The second support race 28 is fitted into the inner peripheral surface of the casing 37 so as to be slidable in the axial direction. A pressing force is applied to the second support race 28 from the cam surface 28p toward the non-input side in the axial direction by the pressing force applying mechanism 7. The pressing force presses the planetary rolling elements 20 against the output race 30.

[0039] FIG. 9 is a perspective view showing the output race 30. The output race 30 has a ring shape that surrounds the shaft 68 and the shaft cap 69. The output race 30 has a rolling surface 30h on the input side. The rolling surface 30h is a surface on which the planetary rolling elements 20 roll, and is in point contact or surface contact with the planetary rolling elements 20. The rolling surface 30h is inclined in the axial direction and the radial direction. The rolling surface 30h includes a tapered surface that reduces in diameter toward the opposite input side. The rolling surface 30h in this example is a conical surface composed of a flat surface. Since the conical surface is a concave surface, the contact surface 20d, which is a convex surface, and the rolling surface 30h are in uneven contact.

[0040] The output race 30 contacts the planetary rolling elements 20 and rotates about the rotation axis La as the planetary rolling elements 20 rotate. The output race 30 is connected to an output member 32 of the output mechanism 5, and the output member 32 rotates as the output race 30 rotates. The output race 30 has a connecting hole 30e that surrounds the rotation axis La and penetrates in the axial direction. A connecting portion 32d of the output member 32 is fitted into the connecting hole 30e. A recess 30k that meshes with a parallel key 35 provided on the outer periphery of the connecting portion 32d is provided in the connecting hole 30e. The output race 30 is provided with a circular protrusion 30b that protrudes toward the opposite input side.

[0041] The operation of the transmission mechanism 3 will be described. When the input race 14 rotates, the planetary rolling elements 20 revolve around the revolution axis while rotating around the rotation axis Lb. In this example, the revolution axis of the planetary rolling elements 20 coincides with the rotation axis La, so the following description will be given assuming that the rotation axis La is the revolution axis.

[0042] When the first support race 26 rotates freely and the second support race 28 is stationary and non-rotating, an output rotation obtained by multiplying the input rotation by the speed ratio R is output to the output race 30. The speed ratio R is determined according to the shape of the planetary rolling elements 20 and the inclination of the rotation axis Lb with respect to the rotation axis La. Therefore, the speed ratio R can be changed by changing the inclination of the rotation axis Lb. The embodiment includes a speed ratio change mechanism 6 in order to change the speed ratio R by changing the inclination of the rotation axis Lb. The speed ratio change mechanism 6 will be described later.

[0043] The output mechanism 5 will be described with reference to Figs. 2 and 10. As shown in Fig. 2, the output mechanism 5 includes an output raceway 30, an output raceway bearing 33, an output member 32, an output bearing 34, a second oil seal S2, and a casing 37. The casing 37 functions as an outer shell that surrounds the internal mechanism of the friction transmission 100. The casing 37 has a cylindrical portion 37b and an inner protruding portion 36. A cover 67 is fixed to the input side of the cylindrical portion 37b with a pressing cam 56 sandwiched therebetween. The inner protruding portion 36 is a ring-shaped portion that protrudes radially inward from the inner circumferential side of the cylindrical portion 37b. The output bearing 34 is accommodated on the opposite input side of the inner protruding portion 36 of the cylindrical portion 37b.

[0044] The output bearing 34 is disposed between the output member 32 and the cylindrical portion 37b, and the input side of the output bearing 34 is supported by the inner protruding portion 36. The output bearing 34 rotatably supports the output member 32. The output bearing 34 in this example is a cross roller bearing. The outer ring of the output bearing 34 is supported by the cylindrical portion 37b, and the inner ring supports the output member 32.

[0045] The second oil seal S2 is disposed on the inner circumferential surface of the cylindrical portion 37b on the anti-input side of the output bearing 34, and provides a seal between the inside of the friction transmission 100 and the outside.

[0046] The output race bearing 33 rotatably supports the output race 30 relative to the inner protruding portion 36 of the casing 37. The output race bearing 33 is disposed between the inner protruding portion 36 and the output race 30 in the axial direction. The output race bearing 33 has a ring shape that is accommodated in the annular space between the cylindrical portion 37b and the circular protruding portion 30b of the output race 30. In other words, the output race bearing 33 fits onto the outer periphery of the circular protruding portion 30b. The output race bearing 33 in this example is a thrust bearing that includes a ring and a plurality of rollers that roll on the ring.

[0047] 10 is a perspective view showing the output member 32. The output member 32 is a generally circular member having, in order from the non-input side, a flange portion 32b, an intermediate portion 32c, and a connecting portion 32d. The flange portion 32b is a disk-shaped portion having a plurality of (e.g., six) tapped holes 32m on the non-input side for bolt connection to a driven device. The plurality of tapped holes 32m are arranged at predetermined intervals on a circumference surrounding the rotation axis La.

[0048] The intermediate portion 32c is continuous with the input side of the flange portion 32b and is a circular portion having a smaller diameter than the flange portion 32b. A circumferential groove 32g is provided around the outer periphery of the intermediate portion 32c, in which a retaining ring W2 is attached to regulate the positional relationship with the output bearing 34. The intermediate portion 32c is supported by the output bearing 34.

[0049] The connecting portion 32d is a circular portion that is continuous with the input side of the intermediate portion 32c and has a smaller diameter than the intermediate portion 32c. A parallel key 35 for fixing is fixed to the outer periphery of the connecting portion 32d by a bolt B2. The parallel key 35 meshes with a recess 30k of the connecting hole 30e. With the connecting portion 32d fitted into the connecting hole 30e, the output member 32 is connected to the output race 30. In this state, the output member 32 and the output race 30 are relatively movable in the axial direction and rotate together in the circumferential direction. A circular recess 32e that is recessed toward the opposite input side in the axial direction is provided on the input side of the connecting portion 32d. The circular recess 32e is a circular recess that surrounds the rotation axis La and has an inner diameter and depth that can accommodate the tip of the shaft 68 and the shaft cap 69 through a gap.

[0050] The pressing force imparting mechanism 7 will be described with reference to Figs. 2, 11, 12, 13, 14, and 15. The pressing force imparting mechanism 7 converts the rotational motion of the second support raceway 28 into linear motion of the second support raceway 28 to impart a preload to the transmission mechanism 3. As shown in Fig. 2, the pressing force imparting mechanism 7 includes a pressing cam 56, a roller retainer 52, a roller 53, a cover 67, and the second support raceway 28. Fig. 11 is a perspective view showing the pressing cam 56. The pressing cam 56 is a ring-shaped member having a through hole 56c, and is disposed between the cylindrical portion 37b and the cover 67. The pressing cam 56 has a plurality of bolt holes 56d for passing the bolts B1. The plurality of bolt holes 56d are disposed at predetermined intervals in the circumferential direction at positions offset from the rotation axis La. The pressing cam 56 has a notch 56k in which a part of the circumferential direction is cut out to allow the control shaft 61 of the speed ratio change mechanism 6 to pass therethrough.

[0051] The pressing cam 56 has a cam surface 56p on the non-input side. The cam surface 56p has a plurality (for example, six) of concave cam grooves 56j each consisting of a first inclined surface 56f and a second inclined surface 56g. The cam grooves 56j have a V-shape when viewed radially from the outer diameter side. The plurality of cam grooves 56j are arranged at predetermined intervals in the circumferential direction and are connected to each other by a connecting surface 56e. The connecting surface 56e can be formed parallel to a plane perpendicular to the rotation axis La. The first inclined surface 56f is inclined with respect to the plane perpendicular to the rotation axis La. The second inclined surface 56g is inclined in the opposite direction to the first inclined surface 56f with respect to the plane perpendicular to the rotation axis La.

[0052] FIG. 12 is a perspective view showing the roller 53 and the roller retainer 52. The roller retainer 52 is a ring-shaped member having a through hole 52c, and is disposed between the cam surface 28p of the second support raceway 28 and the cam surface 56p of the pressing cam 56. The roller retainer 52 has a plurality of (for example, six) pockets 52b disposed at a predetermined interval in the circumferential direction. The pockets 52b are rectangular holes when viewed from the axial direction. A plurality of (for example, six) rollers 53 are provided corresponding to the cam grooves 56j. The rollers 53 have a cylindrical shape and are rotatably accommodated in the pockets 52b. The roller retainer 52 has a cutout portion 52k in which a part of the circumferential direction is cut out to accommodate the radial protrusion portion 62c of the speed ratio change mechanism 6.

[0053] FIG. 13 is a perspective view showing the cover 67. The cover 67 is a hollow disk-shaped member having a hollow portion 67c surrounding the rotation axis La, and is fixed to the input side of the casing 37. The cover 67 has a plurality of bolt holes 67d for passing the bolts B1 through. The plurality of bolt holes 67d are arranged at predetermined intervals in the circumferential direction at positions offset from the rotation axis La, and communicate with the bolt holes 56d of the pressing cam 56. The cover 67 has a through hole 67e for passing the control shaft 61 through. The through hole 67e is arranged at a position offset from the rotation axis La and on the inner circumferential side of the pitch circle of the bolt holes 67d.

[0054] A sleeve bearing 57 and a cylindrical seal 58 are attached to the through hole 67e (see also FIG. 2). The sleeve bearing 57 has a plate-shaped flange that contacts the non-input side of the cover 67 and a cylindrical portion that is fitted into the through hole 67e, and can be made of, for example, sintered metal. The sleeve bearing 57 smoothes the axial movement of the control shaft 61 and suppresses the outflow of the lubricant. The cylindrical seal 58 is disposed on the input side of the sleeve bearing 57 in the through hole 67e, and functions as an oil seal that suppresses the outflow of the lubricant.

[0055] The hollow portion 67c is provided with a circumferential step 67h in contact with the input side of the input bearing 66, and a circumferential groove 67g in which a retaining ring W3 is attached. The retaining ring W3 in contact with the non-input side of the input bearing 66 is attached to the circumferential groove 67g. The axial position of the input bearing 66 is regulated by the retaining ring W3 and the circumferential step 67h.

[0056] FIG. 14 is a perspective view showing a state in which the main components of the speed ratio change mechanism 6 and the pressing force imparting mechanism 7 are attached to the cover 67. The pressing cam 56 and the roller retainer 52 are attached to the non-input side of the cover 67 in an overlapping manner. In this state, the notches 56k and 52k are aligned with the through hole 67e in the circumferential direction. The control ring 62 is attached so that the radial projection 62c (see also FIG. 16) is accommodated in the notches 56k and 52k. The control ring 62 is accommodated in the central space of the pressing cam 56 and the roller retainer 52, and the control shaft 61 penetrates the central holes of the sleeve bearing 57 and the cylindrical seal 58 and protrudes from the input side of the cover 67.

[0057] Fig. 15 is a diagram for explaining the operation of the pressing force imparting mechanism 7, and shows the cam surface 28p, the roller 53, and the cam surface 56p. The pressing cam 56 is fixed to the casing and is stationary, and the second support raceway ring 28 receives a rotational force (torque) and rotates as the planetary rolling body 20 rotates. Fig. 15(A) shows a state in which no rotational force is being received, and Fig. 15(B) shows a state in which a rotational force is being received.

[0058] When the second support race 28 rotates, as shown in Fig. 15(B), the relative positions of the cam groove 28j and the cam groove 56j shift as indicated by the arrow W, and the roller 53 rides up the first inclined surface 56f and the second inclined surface 28g. As a result, a reaction force F0 from the roller 53 is applied to the inclined surface, and a component force of the reaction force F0 becomes a pressing force F, which presses the second support race 28 to the opposite input side. The pressing force F presses the second support race 28, the planetary rolling element 20, the output race 30, and the output race bearing 33 against the inward projection 36, and functions as a preload for the transmission mechanism 3 (see also Fig. 2).

[0059] When the load from the driven device increases and the preload between the output raceway 30 and the planetary rolling elements 20 becomes insufficient, the proportion of the rotational force input from the input raceway 14 to the planetary rolling elements 20 that is transmitted to the second support raceway 28 increases. When the rotational force of the second support raceway 28 increases, the pressing force F, which is a component of the rotational force of the second support raceway 28, increases, and the preload increases. When the load from the driven device decreases, the rotational force transmitted to the second support raceway 28 decreases due to the reverse mechanism, and the pressing force F and preload also decrease. In this way, the pressing force imparting mechanism 7 can impart a pressing force F corresponding to the load from the driven device to the transmission mechanism 3, and automatically adjust the preload.

[0060] The speed ratio change mechanism 6 will be described with reference to Figs. 2 and 16. Fig. 16 is a perspective view showing the speed ratio change mechanism 6. As described above, the speed ratio change mechanism 6 is a mechanism that changes the relative position of the input raceway 14 of the transmission mechanism 3 to control the speed ratio R. As shown in Fig. 2, the speed ratio change mechanism 6 includes a control shaft 61, a control ring 62, and a control section bearing 63. The control shaft 61 is a rod-shaped member that extends in the axial direction at a position radially offset from the rotation axis La, and its opposite input end is attached to a radial protruding portion 62c of the control ring 62. The radial position of the control shaft 61 may be a position that is offset radially outward from the input shaft 64, or may be a position that is offset radially outward from the input raceway 14. The control ring 62 is a ring-shaped member having a hollow portion 62e. A circumferential extension 62f extending radially inward from the non-input side of the hollow portion 62e and a circumferential groove 62g in which a retaining ring W4 is attached are provided around the hollow portion 62e in order to support the control portion bearing 63. The axial movement of the control portion bearing 63 is restricted by the circumferential extension 62f and the retaining ring W4.

[0061] The control section bearing 63 is disposed between the hollow portion 62e of the control ring 62 and the first cylindrical portion 15b of the sleeve 15. The control section bearing 63 rotatably supports the sleeve 15 with respect to the speed ratio change mechanism 6. The outer ring of the control section bearing 63 is supported in the hollow portion 62e of the control ring 62, and the inner ring supports the first cylindrical portion 15b. The control section bearing 63 in this example is a cross roller bearing. The control shaft 61 extends from the radial protruding portion 62c to the input side, penetrates the pressing cam 56 and the cover 67, and protrudes to the input side of the cover 67. The control shaft 61 is connected to an actuator (not shown) that outputs a driving force in the axial direction. The non-input side of the control ring 62 is accommodated in the through hole 52c of the roller retainer 52.

[0062] The operation of the speed ratio change mechanism 6 will be described. When an axial driving force is input from the actuator to the control shaft 61, the control ring 62 moves in the axial direction. In conjunction with the movement of the control ring 62, the control section bearing 63, sleeve 15, input race 14, first race bearing 27, first support race 26, shaft 68 and shaft cap 69 move integrally. At this time, since the second support race 28 and the output race 30 are stationary in the axial direction, the rotation axis Lb of the planetary rolling element 20 tilts with respect to the rotation axis La.

[0063] When the input raceway 14 and the first support raceway 26 move toward the opposite input side, the opposite input side of the rotating shaft Lb moves away from the rotation axis La, and the input side of the rotating shaft Lb tilts toward the rotation axis La. As a result, the rotation radius and revolution radius of each contact point between each raceway and the planetary rolling element 20 change, and the speed ratio R also changes. The speed ratio R (output rotation / input rotation) of the friction transmission 100 increases as the inclination with respect to the rotation axis La increases. Similarly, when the input raceway 14 and the first support raceway 26 move toward the input side, the rotating shaft Lb tilts toward the opposite side, and the speed ratio R of the friction transmission 100 decreases as the inclination with respect to the rotation axis La increases. By maintaining the position of the control shaft 61 constant, the attitude of the planetary rolling element 20 becomes constant, and the speed ratio R is kept constant.

[0064] The operation of the friction transmission 100 configured as above will be described. When rotation is transmitted from the motor shaft 51 to the input shaft 64, the input race 14 rotates around the rotation axis La. The rotation of the input race 14 causes the planetary rolling elements 20 to rotate and revolve. The rotation of the planetary rolling elements 20 is transmitted to the output race 30, which rotates at a speed according to the speed ratio R. The rotation of the output race 30 is output to the output member 32 through the output mechanism 5. When the speed ratio change mechanism 6 changes the positions of the input race 14 and the first support race 26 (hereinafter simply referred to as "position T"), the speed ratio R also changes.

[0065] The characteristic configuration of the present disclosure will be described below. The friction transmission 100 of the embodiment is configured such that the first shape parameter of the first contact surface 20d that contacts the rolling surface 30h of the output raceway 30 of the planetary rolling body 20 and the second shape parameter of the second contact surface 20c that contacts the rolling surface 28h of the second support raceway 28 of the planetary rolling body 20 are different from each other. In other words, the shapes of the first contact surface 20d and the second contact surface 20c that contact the two outer raceways of the planetary rolling body 20 are different from each other. The shape parameter of the contact surface that contacts the rolling surface is a variable that defines the rolling surface, the contact surface, and the contact point. In other words, the friction transmission 100 is configured such that the rolling surface 30h and the first contact surface 20d, and the rolling surface 28h and the second contact surface 20c are asymmetric with respect to the equatorial plane. The specific configuration will be described later.

[0066] In order to facilitate understanding of the characteristic configuration, the contact configuration of the planetary rolling element 20 and each raceway of the reference example 200 will be described. The reference example 200 was created by the present inventor in the process of developing this embodiment. Fig. 23(A) shows the configuration of the planetary rolling element 20 and each raceway of the reference example 200, and Fig. 23(B) shows the speed ratio control characteristic G of the reference example 200. Fig. 23(A) shows the contour lines (hereinafter referred to as "sectional curves") appearing in each cross section of the planetary rolling element 20, the input raceway 14, the first support raceway 26, the second support raceway 28, and the output raceway 30 in a plane including the central axis La and the rotation axis Lb.

[0067] Reference example 200 differs from the embodiment in that the first shape parameter and the second shape parameter are configured to be the same. In reference example 200, rolling surface 30h and first contact surface 20d, and rolling surface 28h and second contact surface 20c are configured symmetrically with respect to the equatorial plane.

[0068] The speed ratio control characteristic G of the reference example 200 will be explained. In FIG. 23(B), the horizontal axis indicates the position T of the speed ratio change mechanism 6, and the vertical axis indicates the speed ratio R (output rotation / input rotation). In the speed ratio R, the positive side means that the output rotation is in the same direction as the input rotation (forward rotation), and the negative side means that the output rotation is in the opposite direction to the input rotation (reverse rotation). Also, the larger the absolute value of the speed ratio R, the faster the output rotation. Also, the speed ratio R=0 (zero) means that the output rotation=0, that is, there is no rotation. That is, in the friction transmission, the speed ratio R can be changed by moving the position T of the speed ratio change mechanism 6 from the neutral position Tp to one side and from the neutral position Tp to the other side. The position T where the rotation axis Lb of the planetary rolling element 20 is parallel to the rotation axis La of the input raceway ring 14 is called the neutral position Tp. In the diagram showing the speed ratio control characteristic G, the position T is shown as a relative value with respect to the neutral position Tp.

[0069] As shown in FIG. 23(B), in the reference example 200, the speed ratio change mechanism 6 is configured so that the movable amount N1 from the neutral position Tp to one side and the movable amount N2 from the neutral position Tp to the other side are the same. The movable amount of the speed ratio change mechanism 6 is set within a range in which the contact point does not go beyond the rolling surface of the planetary rolling body or the raceway surface of the raceway ring and the error of the speed ratio can be tolerated. The speed ratio control characteristic G of the reference example 200 is symmetrical on the plus side and the minus side of the speed ratio R, and may not be applicable to applications in which the speed ratio R on one side is increased. Therefore, the friction transmission 100 of the embodiment has a first shape parameter and a second shape parameter that are different from each other so that it can be applied to applications in which the speed ratio R on one side is increased. The first shape parameter and the second shape parameter may be collectively referred to simply as "shape parameters". Below, explanations will be given with reference to several configuration examples.

[0070] (First and second configuration examples) First and second configuration examples of the friction transmission 100 of the embodiment will be described with reference to Figures 17 and 18. Figure 17(A) shows a first configuration example of the planetary rolling elements 20 and each raceway, and Figure 17(B) shows the speed ratio control characteristic G of the first configuration example. Figure 18(A) shows a second configuration example of the planetary rolling elements 20 and each raceway, and Figure 18(B) shows the speed ratio control characteristic G of the second configuration example.

[0071] In the first and second configuration examples, the outermost diameter K1 of the first contact surface 20d and the outermost diameter K2 of the second contact surface 20c of the planetary rolling element 20 are different from each other. In the first configuration example, the outermost diameter K1 of the first contact surface 20d is smaller than the outermost diameter K2 of the second contact surface 20c. The outermost diameter K1 and the outermost diameter K2 are examples of shape parameters. In the second configuration example, the outermost diameter K1 of the first contact surface 20d is larger than the outermost diameter K2 of the second contact surface 20c.

[0072] In addition, in the first and second configuration examples, as shown in the speed ratio control characteristic G, the amount of movement N1 of the speed ratio change mechanism 6 from the neutral position Tp to one side and the amount of movement N2 from the neutral position Tp to the other side are configured to be different from each other.

[0073] In the first configuration example, the movable amount N1 to the plus side is larger than the movable amount N2 to the minus side, the maximum amount (absolute value) M1 of the plus side gear ratio R is larger than that of the reference example, and the maximum amount (absolute value) M2 of the minus side gear ratio R is smaller than that of the reference example. In other words, the maximum amount (absolute value) M1 of the plus side gear ratio R is smaller than the maximum amount (absolute value) M2 of the minus side gear ratio R.

[0074] In the second configuration example, the movable amount N2 to the negative side is larger than the movable amount N1 to the positive side, the maximum amount (absolute value) M2 of the negative side gear ratio R is larger than that of the reference example, and the maximum amount (absolute value) M1 of the positive side gear ratio R is smaller than that of the reference example. In other words, the maximum amount (absolute value) M2 of the negative side gear ratio R is smaller than the maximum amount (absolute value) M1 of the negative side gear ratio R. The first configuration example is suitable for applications requiring high speed rotation on the positive side, and the second configuration example is suitable for applications requiring high speed rotation on the negative side.

[0075] (Third and fourth configuration examples) Third and fourth configuration examples of the friction transmission 100 of the embodiment will be described with reference to Figures 19 and 20. Figure 19(A) shows a third configuration example of the planetary rolling elements 20 and each raceway, and Figure 19(B) shows the speed ratio control characteristic G of the third configuration example. Figure 20(A) shows a fourth configuration example of the planetary rolling elements 20 and each raceway, and Figure 20(B) shows the speed ratio control characteristic G of the fourth configuration example.

[0076] In the third and fourth configuration examples, when the rotation axis Lb of the planetary rolling element 20 is parallel to the rotation axis La of the input race 14, the radial distance D1 from the rotation axis Lb of the contact point 30c on the first contact surface 20d and the radial distance D2 from the rotation axis Lb of the contact point 28c on the second contact surface 20c are different from each other. In the third configuration example, the radial distance D1 is smaller than the radial distance D2. In the fourth configuration example, the radial distance D1 is larger than the radial distance D2. The radial distance D1 and the radial distance D2 are examples of shape parameters.

[0077] To achieve this configuration, in the third and fourth configuration examples, the inclination angle θ1 of the area of ​​the rolling surface 30h of the output race 30 that contacts the planetary rolling elements 20 relative to the rotation axis La and the inclination angle θ2 of the area of ​​the rolling surface 28h of the second support race 28 that contacts the planetary rolling elements 20 relative to the rotation axis La are different from each other. In the third configuration example, the inclination angle θ1 is larger than the inclination angle θ2. In the fourth configuration example, the inclination angle θ1 is smaller than the inclination angle θ2. The inclination angles θ1 and θ2 are examples of shape parameters.

[0078] In the third configuration example, as shown in Fig. 19(B), the movable amount N1 to the plus side and the movable amount N2 to the minus side are relative distances from the neutral position Tp and are equal to each other, the maximum amount (absolute value) M1 of the speed ratio R on the plus side is larger than that of the reference example, and the maximum amount (absolute value) M2 of the speed ratio R on the minus side is smaller than that of the reference example. Also, at the neutral position Tp, the speed ratio R is not zero but is offset by M0 to the plus side. The third configuration example is suitable for applications requiring high speed rotation on the plus side.

[0079] In the fourth configuration example, as shown in Fig. 20(B), the movable amount N1 to the plus side and the movable amount N2 to the minus side are relative distances from the neutral position Tp and are equal to each other, the maximum amount (absolute value) M2 of the gear ratio R on the minus side is larger than that of the reference example, and the maximum amount (absolute value) M1 of the gear ratio R on the plus side is smaller than that of the reference example. Also, at the neutral position Tp, the gear ratio R is not zero but is offset by M0 to the minus side. The fourth configuration example is suitable for applications requiring high speed rotation on the minus side.

[0080] (Fifth and sixth configuration examples) With reference to Figures 21 and 22, fifth and sixth configuration examples of the friction transmission 100 of the embodiment will be described. Figure 21(A) shows a fifth configuration example of the planetary rolling elements 20 and each raceway, and Figure 21(B) shows the speed ratio control characteristic G of the fifth configuration example. Figure 22(A) shows a sixth configuration example of the planetary rolling elements 20 and each raceway, and Figure 22(B) shows the speed ratio control characteristic G of the sixth configuration example.

[0081] In the embodiment of the friction transmission 100, the first, second, third, and fourth configuration examples can be combined with each other within a configurable range. The fifth configuration example is a combination of the first and third configuration examples, and the sixth configuration example is a combination of the second and fourth configuration examples.

[0082] In the fifth and sixth configuration examples, when the rotation axis Lb of the planetary rolling element 20 is parallel to the rotation axis La of the input race 14, the radial distance D1 and the radial distance D2 are different from each other, the outermost diameter K1 and the outermost diameter K2 are different from each other, and the inclination angle θ1 and the inclination angle θ2 are different from each other. In the fifth configuration example, the outermost diameter K1 is smaller than the outermost diameter K2, the inclination angle θ1 is larger than the inclination angle θ2, and the radial distance D1 is smaller than the radial distance D2. In the sixth configuration example, the outermost diameter K1 is larger than the outermost diameter K2, the inclination angle θ1 is smaller than the inclination angle θ2, and the radial distance D1 is larger than the radial distance D2.

[0083] In the fifth configuration example, as shown in Fig. 21(B), the movable amount N1 to the plus side and the movable amount N2 to the minus side are relative distances from the neutral position Tp, and the movable amount N1 to the plus side is greater than the movable amount N2 to the minus side, the maximum amount (absolute value) M1 of the speed ratio R on the plus side is greater than that of the reference example, and the maximum amount (absolute value) M2 of the speed ratio R on the minus side is smaller than that of the reference example. Also, at the neutral position Tp, the speed ratio R is not zero but is offset by M0 to the plus side. The fifth configuration example is more suitable for applications requiring high speed rotation on the plus side.

[0084] In the sixth configuration example, as shown in Fig. 22(B), the movable amount N1 to the plus side and the movable amount N2 to the minus side are relative distances from the neutral position Tp, and the movable amount N2 to the minus side is greater than the movable amount N1 to the plus side, the maximum amount (absolute value) M2 of the gear ratio R on the minus side is greater than that of the reference example, and the maximum amount (absolute value) M1 of the gear ratio R on the plus side is smaller than that of the reference example. Also, at the neutral position Tp, the gear ratio R is not zero but is offset by M0 to the minus side. The sixth configuration example is more suitable for applications requiring high speed rotation on the minus side.

[0085] The operation and effect of the friction transmission 100 of the embodiment will be described. The friction transmission 100 of the embodiment is a friction transmission device including an input raceway 14, planetary rolling elements 20 arranged around the rotation axis La of the input raceway 14 and in contact with the input raceway 14, an output raceway 30 in contact with the planetary rolling elements 20 and connected to an output member 32, and a first support raceway 26 and a second support raceway 28 in contact with the planetary rolling elements 20. The gear ratio change mechanism 6 changes the speed ratio by changing the relative positions of the two inner driving rings located on the inside of the planetary rolling body 20 and the two outer driving rings located on the outside of the planetary rolling body 20, among the input race 14, output race 30, first support race 26 and second support race 28, and is configured so that the maximum amount M1 of the absolute value of the speed ratio on the positive side where the output rotation is in the same direction as the input rotation and the maximum amount M2 of the absolute value of the speed ratio on the negative side where the output rotation is in the opposite direction to the input rotation are different, and the shapes of the first contact surface 20d and the second contact surface 20c that come into contact with the two outer races of the planetary rolling body 20 are different from each other.

[0086] According to this configuration, the first contact surface 20d and the second contact surface 20c are asymmetrically configured to have mutually different shapes, so that the gear ratio R (absolute value) on one side of the positive and negative sides of the gear ratio R can be increased. Therefore, the gear ratio R on one side can be increased more than in a symmetrical configuration, and the range of the gear ratio R can be used more effectively according to the needs of the application. Furthermore, the friction transmission 100 of the embodiment can be applied to cases where an engine is used as the prime mover, but is particularly suitable for cases where a servo motor capable of controlling the rotation speed over a wide range is used as the prime mover.

[0087] As an example, in the friction transmission 100, at least one of the input raceway 14, the output raceway 30, the first support raceway 26, and the second support raceway 28 is a convex-concave contact raceway that makes convex-concave contact with the planetary rolling element 20. In this case, the contact stress at the contact portion is lower than in the case of convex-convex contact, and the life of the contact portion can be extended.

[0088] As an example, the friction transmission 100 is configured such that the amount of movement of the speed ratio change mechanism 6 from the neutral position to one side is different from the amount of movement of the speed ratio change mechanism 6 from the neutral position to the other side. In this case, since the amount of movement is different, it is possible to increase the speed ratio R (absolute value) on one side, which has a larger amount of movement, between the positive side and the negative side of the speed ratio R.

[0089] As an example, in the friction transmission 100, the outermost diameter of the first contact surface 20d and the outermost diameter of the second contact surface 20c of the planetary rolling element 20 are different from each other. In this case, the amount of movement is larger on one side where the outermost diameter of the contact surface is larger than on the other side where the outermost diameter is smaller, so that the speed ratio R (absolute value) on one side can be increased.

[0090] As an example, in the friction transmission 100, when the rotation axis of the planetary rolling element 20 is parallel to the rotation axis La, the radial distance from the rotation axis to the contact point on the first contact surface 20d is different from the radial distance from the rotation axis to the contact point on the second contact surface 20c. For example, when the radial distance D1<the radial distance D2, the speed ratio R (absolute value) on the plus side can be increased, and when the radial distance D1>the radial distance D2, the speed ratio R (absolute value) on the minus side can be increased.

[0091] As an example, in the friction transmission 100, when the rotation axis of the planetary rolling element 20 is parallel to the rotation axis La, the inclination angle of the region of the rolling surface of the output race 30 that comes into contact with the planetary rolling element 20 relative to the rotation axis is different from the inclination angle of the region of the rolling surface of the second support race 28 that comes into contact with the planetary rolling element 20 relative to the rotation axis. For example, when the inclination angle θ1 is greater than the inclination angle θ2, the speed ratio R (absolute value) on the plus side can be increased. For example, when the inclination angle θ1 is less than the inclination angle θ2, the speed ratio R (absolute value) on the minus side can be increased.

[0092] The present invention has been described above based on several embodiments. These embodiments are illustrative, and various modifications and changes are possible within the scope of the claims of the present invention, and it is understood by those skilled in the art that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the description and drawings in this specification should be treated as illustrative rather than restrictive.

[0093] (Modification) The following describes the modified examples. In the drawings and description of the modified examples, the same or equivalent components and members as those in the embodiment are denoted by the same reference numerals. Descriptions that overlap with the embodiment will be omitted as appropriate, and the description will focus on configurations that differ from the embodiment.

[0094] In the description of the embodiment, an example has been shown in which the output member 32 and the output race 30 are key-connected by the parallel key 35, but there are no limitations to these connection structures. These connection structures may be any structure that allows them to move relatively in the axial direction and rotate together in the circumferential direction, and may employ, for example, a spline connection, an involute spline connection, or a connection using an elastic body such as a spring that has low rigidity in the axial direction and high rigidity in the circumferential direction.

[0095] In the description of the embodiment, an example has been given in which the rolling surfaces 30h and 28h are conical surfaces constituted by flat surfaces, but these may also be curved surfaces such as convex surfaces or concave surfaces.

[0096] The configuration of the input bearing 66 is not limited, and may be, for example, a bearing having rollers as rolling elements. The configuration of the first raceway bearing 27 is not limited, and may be, for example, a bearing having rollers as rolling elements. The configuration of the output raceway bearing 33 is not limited, and may be, for example, a bearing having spheres as rolling elements. The configuration of the output bearing 34 is not limited, and may be, for example, a bearing having spheres as rolling elements.

[0097] The configuration of the control section bearing 63 is not limited, and may be, for example, a bearing having balls as rolling elements, a thrust bearing, a sliding bearing, or the like.

[0098] For example, the pressing force imparting mechanism 7 may have a sphere instead of the roller 53, and the pocket 52b of the roller retainer 52, the cam groove 56j of the pressing cam 56, and the cam groove 28j of the second support raceway 28 may each have a shape corresponding to the sphere.

[0099] For example, in the pressing force imparting mechanism 7, the roller 53 and the roller retainer 52 may be eliminated, and the cam groove 28j of the second support race 28 may be a convex cam lobe having a V-shaped slope, which the cam groove 56j of the pressing cam 56 directly contacts. Conversely, the area of ​​the pressing cam corresponding to the cam groove 56j may be a cam lobe.

[0100] In the description of the embodiment, the input race 14 is disposed radially inward and the output race 30 is disposed radially outward with respect to the rotation axis of the planetary rolling elements 20. However, this is not limited to this, and the input race 14 may be disposed on the outside and the output race 30 on the inside, or both may be disposed on the inside, or both may be disposed on the outside.

[0101] Each of these modified examples provides the same functions and effects as the embodiment.

[0102] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the respective embodiments and modifications. [Explanation of symbols]

[0103] 6 speed ratio change mechanism, 14 input raceway, 14h rolling surface, 20 planetary rolling elements, 20a, 20b, 20c, 20d contact surface, 26 first support raceway, 26h rolling surface, 28 second support raceway, 28c contact point, 28h rolling surface, 30 output raceway, 30c contact point, 30h rolling surface, 32 output member, 100 friction transmission device.

Claims

1. A friction transmission comprising: an input raceway; planetary rolling elements arranged around a rotation axis of the input raceway and in contact with the input raceway; an output raceway in contact with the planetary rolling elements and connected to an output member; and a first support raceway and a second support raceway in contact with the planetary rolling elements, a speed ratio change mechanism that changes a speed ratio by changing a relative position of two inner driving rings located inside the planetary rolling elements, among the input race, the output race, the first support race, and the second support race, and two outer races located outside the planetary rolling elements, The speed ratio changed by the speed ratio change mechanism has a maximum absolute value different from a maximum absolute value of a speed ratio on a positive side where the output rotation is in the same direction as the input rotation, and a maximum absolute value of a speed ratio on a negative side where the output rotation is in the opposite direction to the input rotation, A friction transmission device in which the shapes of a first contact surface and a second contact surface of the planetary rolling element that come into contact with the two outer raceways are different from each other.

2. 2. The friction transmission device according to claim 1, wherein at least one of the input raceway, the output raceway, the first support raceway and the second support raceway is a convex-concave contact race that comes into convex-concave contact with the planetary rolling elements.

3. 2. The friction transmission device according to claim 1, wherein an amount by which the speed ratio change mechanism can move from a neutral position to one side is different from an amount by which the speed ratio change mechanism can move from the neutral position to the other side.

4. 4. The friction transmission according to claim 3, wherein an outermost diameter of the first contact surface of the planetary rolling element is different from an outermost diameter of the second contact surface of the planetary rolling element.

5. 2. The friction transmission device according to claim 1, wherein, when the rotation axis of the planetary rolling body is parallel to the rotation axis, a radial distance from the rotation axis of a contact point on the first contact surface and a radial distance from the rotation axis of a contact point on the second contact surface are different from each other.

6. 6. The friction transmission according to claim 5, wherein, when the rotation axis of the planetary rolling elements is parallel to the rotation axis, an inclination angle of the region of the rolling surface of the output ring that contacts the planetary rolling elements with respect to the rotation axis and an inclination angle of the region of the rolling surface of the second support ring that contacts the planetary rolling elements with respect to the rotation axis are different from each other.

Images