Toroidal type continuously variable transmission

Abstract

To provide a toroidal type continuously variable transmission capable of facilitating the finishing processing of a traction surface of a power roller, and capable of securing a processing reference of a required width in an outside diameter portion serving as a reference in post-processing.SOLUTION: A toroidal type continuously variable transmission includes a first disk 2 and a second disk 3 concentrically and rotatably provided with each other, and a power roller 40 held between the first disk and the second disk, and traction drive is performed by the first disk and the second disk and the power roller. An inner ring 55 of the power roller 40 has a traction surface 55c having a circular arc cross section on an outer peripheral surface thereof, and in an outer diameter portion 55d, the inner ring 55 has a step surface 55s positioned inside in a radial direction relative to an extension surface 55e of the traction surface 55c and serving as a processing reference of at least the traction surface 55c.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a toroidal type continuously variable transmission that can be used in generators for automobiles and aircraft, or transmissions for various industrial machines, etc. [Background technology]

[0002] For example, a double-cavity toroidal type continuously variable transmission used as an automobile transmission is configured as shown in Figures 3 and 4. As shown in Figure 3, an input shaft 1 is rotatably supported inside a casing 50, and two input side discs 2, 2 and two output side discs 3, 3 are attached to the outer periphery of this input shaft 1. An output gear (transmission gear) 4 is rotatably supported on the outer periphery of a middle part of the input shaft 1. The output side discs 3, 3 are connected to cylindrical flange portions 4a, 4a provided in the center of this output gear 4 by spline coupling. The input shaft 1 is rotated by a drive shaft 22 via a loading cam type pressing device 12 provided between the input side disc 2 located on the left side in Fig. 3 and a cam plate (loading cam) 7. The output gear 4 is supported in a casing 50 via a partition wall 13 formed by joining two members, which allows the output gear 4 to rotate about the axis O of the input shaft 1 while preventing displacement in the direction of the axis O.

[0003] The output side discs 3, 3 are supported rotatably about the axis O of the input shaft 1 by needle bearings 5, 5 interposed between them and the input shaft 1. The input side disc 2 on the left side in FIG. 3 is supported on the input shaft 1 via a ball spline 6, and the input side disc 2 on the right side in FIG. 3 is spline-connected to the input shaft 1, so that these input side discs 2 rotate together with the input shaft 1. Power rollers 11 (see FIG. 4) are rotatably sandwiched between inner surfaces (concave surfaces; also called traction surfaces) 2a, 2a of the input side discs 2, 2 and inner surfaces (concave surfaces; also called traction surfaces) 3a, 3a of the output discs 3, 3.

[0004] A step portion 2b is provided on the inner peripheral surface 2c of the input side disc 2 located on the right side in Fig. 3, and a step portion 1b provided on the outer peripheral surface 1a of the input shaft 1 abuts against this step portion 2b, and the back surface (right surface in Fig. 3) of the input side disc 2 abuts against a loading nut 9 screwed into a threaded portion formed on the outer peripheral surface of the input shaft 1. This substantially prevents the input side disc 2 from being displaced in the direction of the axis O relative to the input shaft 1. In addition, a disc spring 8 is provided between the cam plate 7 and the flange portion 1d of the input shaft 1, and this disc spring 8 applies a pressing force (preload) to the contact portions between the concave surfaces 2a, 2a, 3a, 3a of the discs 2, 2, 3, 3 and the peripheral surfaces 11a, 11a of the power rollers 11, 11 shown in Fig. 4.

[0005] FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. As shown in FIG. 4, a pair of trunnions 15, 15 are provided inside the casing 50, which swing about a pair of pivots 14, 14 that are in a twisted position relative to the input shaft 1. Note that the input shaft 1 is not shown in FIG. 4. Each trunnion 15, 15 has a pair of bent wall portions 20, 20 formed at both ends in the longitudinal direction (vertical direction in FIG. 4) of the support plate portion 16, in a state of bending toward the inner surface side of the support plate portion 16. The bent wall portions 20, 20 form a concave pocket portion P in each trunnion 15, 15 for accommodating the power roller 11. In addition, the pivots 14, 14 are provided concentrically with each other on the outer surfaces of the bent wall portions 20, 20.

[0006] A circular hole 21 is formed in the center of the support plate portion 16, and a base end portion 23a of a displacement shaft 23 is supported in this circular hole 21. The inclination angle of the displacement shaft 23 supported in the center of each of the trunnions 15 can be adjusted by swinging each of the trunnions 15 about each of the pivots 14. The power rollers 11 are rotatably supported around the tip portion 23b of the displacement shaft 23 protruding from the inner surface of each of the trunnions 15, and each of the power rollers 11 is sandwiched between each of the input side disks 2 and each of the output side disks 3. The base end portion 23a and the tip portion 23b of each of the displacement shafts 23 are eccentric to each other.

[0007] The pivots 14, 14 of the trunnions 15, 15 are supported by the pair of yokes 23A, 23B so as to be swingable and displaceable in the axial direction (up and down direction in FIG. 4), and the horizontal movement of the trunnions 15, 15 is restricted by the yokes 23A, 23B. The yokes 23A, 23B are formed into a rectangular shape by pressing or forging a metal such as steel. Four circular support holes 18 are provided at the four corners of the yokes 23A, 23B, and the pivots 14 provided at both ends of the trunnions 15 are supported swingably in the support holes 18 via radial needle bearings 30. The yokes 23A, 23B are provided at the center of the width direction (left and right direction in FIG. 4) with circular locking holes 19, and the inner peripheral surface of the locking holes 19 is cylindrical, and spherical posts 64, 68 are fitted into the inner peripheral surface of the locking holes 19. That is, the upper yoke 23A is supported so as to be freely swingable by a spherical post 64 which is supported on the casing 50 via a fixed member 52, and the lower yoke 23B is supported so as to be freely swingable by a spherical post 68 and the upper cylinder body 61 of the drive cylinder 31 which supports it.

[0008] The displacement shafts 23, 23 provided on each trunnion 15, 15 are provided at positions 180 degrees opposite to each other with respect to the input shaft 1. The direction in which the tip end 23b of each of these displacement shafts 23, 23 is eccentric with respect to the base end 23a is the same direction as the rotation direction of both disks 2, 2, 3, 3 (upside down direction in FIG. 4). The eccentric direction is approximately perpendicular to the arrangement direction of the input shaft 1. Therefore, each power roller 11, 11 is supported so as to be slightly displaceable in the longitudinal direction of the input shaft 1. As a result, even if each power roller 11, 11 tends to be displaced in the axial direction of the input shaft 1 due to elastic deformation of each component based on the thrust load generated by the pressing device 12, this displacement is absorbed without applying excessive force to each component.

[0009] Between the outer surface of the power roller 11 and the inner surface of the support plate portion 16 of the trunnion 15, a thrust ball bearing (thrust bearing) 24, which is a thrust rolling bearing, and a thrust needle bearing 25 are provided in this order from the outer surface side of the power roller 11. Of these, the thrust ball bearing 24 supports the thrust load applied to each power roller 11 while allowing each power roller 11 to rotate. Each thrust ball bearing 24 is composed of a plurality of balls (hereinafter referred to as rolling elements) 26, 26, an annular cage 27 that holds each of the rolling elements 26, 26 so that they can roll freely, and an annular outer ring 28. The inner ring raceway of each thrust ball bearing 24 is formed on the outer surface (large end surface) of each power roller 11, and the outer ring raceway is formed on the inner surface of each outer ring 28.

[0010] In addition, the thrust needle bearing 25 is sandwiched between the inner surface of the support plate portion 16 of the trunnion 15 and the outer surface of the outer ring 28. Such thrust needle bearing 25 supports the thrust load applied from the power rollers 11 to each outer ring 28, while allowing the power rollers 11 and the outer ring 28 to swing around the base end portion 23a of each displacement shaft 23.

[0011] Furthermore, a drive rod (trunnion shaft) 29, 29 is provided at one end (lower end in FIG. 4) of each trunnion 15, 15, and a drive piston (hydraulic piston) 33, 33 is fixed to the outer circumferential surface of the middle part of each drive rod 29, 29. Each of these drive pistons 33, 33 is oil-tightly fitted into a drive cylinder 31 formed by an upper cylinder body 61 and a lower cylinder body 62. Each of these drive pistons 33, 33 and the drive cylinder 31 constitutes a drive unit 32 that displaces each of the trunnions 15, 15 in the axial direction of the pivots 14, 14 of the trunnions 15, 15.

[0012] In the case of a toroidal type continuously variable transmission configured in this manner, as shown in Fig. 3, the rotation of the input shaft 1 is transmitted to the input side discs 2, 2 via a pressing device 12. The rotation of these input side discs 2, 2 is then transmitted to the output side discs 3, 3 via a pair of power rollers 11, 11 (see Fig. 4), and the rotation of each of the output side discs 3, 3 is further taken out by the output gear 4.

[0013] When changing the rotational speed ratio between the input shaft 1 and the output gear 4, the pair of drive pistons 33, 33 are displaced in opposite directions. With the displacement of each of the drive pistons 33, 33, the pair of trunnions 15, 15 are displaced in opposite directions. For example, the power roller 11 on the left side of Fig. 4 is displaced downward in the same figure, and the power roller 11 on the right side of the same figure is displaced upward in the same figure. 3 and 4, the direction of the tangential force acting on the contact portions between the peripheral surfaces 11a, 11a of the power rollers 11, 11 and the inner surfaces 2a, 2a, 3a, 3a of the input side disks 2, 2 and the output side disks 3, 3 changes. Then, with the change in the direction of the force, the trunnions 15, 15 swing (tilt) in opposite directions to each other about the pivots 14, 14 pivoted to the yokes 23A, 23B.

[0014] As a result, as shown in Fig. 3 and Fig. 4, the contact position between the peripheral surface 11a, 11a of each power roller 11, 11 and each inner surface 2a, 3a changes, and the rotation speed ratio between the input shaft 1 and the output gear 4 changes. In addition, when the torque transmitted between the input shaft 1 and the output gear 4 fluctuates and the elastic deformation amount of each component changes, each power roller 11, 11 and the outer rings 28, 28 attached to each power roller 11, 11 rotate slightly around the base end portion 23a, 23a of each displacement shaft 23, 23. Since the thrust needle bearings 25, 25 are present between the outer surface of each outer ring 28, 28 and the inner surface of the support plate portion 16 constituting each trunnion 15, 15, the rotation is performed smoothly. Therefore, as described above, a small force is required to change the inclination angle of each displacement shaft 23, 23.

[0015] Incidentally, the traction surface of the power roller of a toroidal type continuously variable transmission is subjected to a super-finishing process after grinding in order to ensure its traction drive function (power transmission) (see, for example, Patent Document 1). For example, as shown in FIG. 5, during superfinishing of the traction surface 11a, a grinding wheel gw perpendicular to the traction surface 11a of the inner ring 11A of the rotating power roller 11 is pressed against the traction surface 11a and moved (oscillated) along the traction surface 11a. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] JP 2003-148577 A Summary of the Invention [Problem to be solved by the invention]

[0017] However, if the grinding wheel gw goes over the end of the finished surface of the traction surface 11a, it will interfere with the outer diameter portion (the portion constituting the outer diameter on the large end face side of the inner ring 11A of the power roller 11) that serves as the reference for post-processing. For this reason, the grinding wheel gw cannot finish the traction surface 11a up to the end of the finished surface, so the shape of the traction drive effective range that is satisfactory in terms of design cannot be secured, making it difficult to finish the traction surface 11a.

[0018] In addition, the above-mentioned outer diameter portion of the power roller (the portion constituting the outer diameter on the large end face side of the power roller (inner ring)) is used as a processing reference (shoe abutment portion) for coaxially processing the traction surface, the shaft hole (a hole into which a support shaft for rotatably supporting the power roller is inserted), and the bearing groove (a groove into which a thrust bearing for rotatably supporting the power roller is inserted), and the width of the portion must be secured by several mm. Therefore, as mentioned above, if the grinding wheel goes over the finishing surface edge of the traction surface, it will interfere with the outer diameter portion that serves as the reference in post-processing, making it difficult to secure the processing reference.

[0019] The present invention has been made in consideration of the above circumstances, and aims to provide a toroidal type continuously variable transmission that can easily perform finish processing of the traction surface of the power roller and can ensure a required width processing standard for the outer diameter portion that serves as the reference for post-processing. [Means for solving the problem]

[0020] In order to achieve the above object, the toroidal type continuously variable transmission of the present invention comprises a first disk and a second disk, which are concentrically and rotatably arranged with their inner surfaces facing each other; a power roller sandwiched between the first disc and the second disc, and a traction drive is performed by the first disc, the second disc and the power roller, The power roller has a traction surface having an arc-shaped cross section on its outer circumferential surface, and a stepped surface on its outer diameter portion, located radially inward from the extension surface of the traction surface, and serving as a machining reference for at least the traction surface. In the above-mentioned configuration of the present invention, the step surface may be formed of a cylindrical surface having an axis coincident with the rotation axis of the power roller.

[0021] Here, the "outer diameter portion" refers to a portion that constitutes the outer diameter on the large end face side of the power roller (inner ring). In addition, since the traction surface is formed by a spherical surface with a single radius R, the "extended surface" means a spherical surface that is a continuous extension of this single radius R shape (spherical surface) from the traction surface.

[0022] In the present invention, the outer diameter portion of the power roller has a step surface located radially inward from the extension surface of the traction surface and serving as at least a processing reference for the traction surface, so that even if the grinding wheel goes over the end of the finished surface of the traction surface, it will not interfere with the step surface that serves as a reference in post-processing. In this way, interference of the grinding wheel in the finish processing of the traction surface of the power roller can be avoided, so that the finish processing of the traction surface can be easily performed, and the step surface can ensure a processing reference of the required width on the outer diameter portion that serves as a reference in post-processing. Effect of the Invention

[0023] According to the present invention, the finish processing of the traction surface of the power roller can be easily performed, and the processing standard of the required width can be secured for the outer diameter portion that serves as the reference for post-processing. [Brief description of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing a power roller of a toroidal type continuously variable transmission according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an inner ring of a power roller of a toroidal type continuously variable transmission according to an embodiment of the present invention, and is a schematic diagram showing a main part. [Diagram 3] FIG. 1 is a cross-sectional view showing an example of a conventional toroidal type continuously variable transmission. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 1 is a diagram showing a schematic diagram of an inner ring of a power roller of a conventional toroidal type continuously variable transmission. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The toroidal type continuously variable transmission of this embodiment differs mainly from the conventional toroidal type continuously variable transmission shown in Figures 3 and 4 in the configuration of the power rollers, so this will be described below, and other identical components will be given the same reference numerals and their description may be omitted or simplified. Also, the configuration of the toroidal type continuously variable transmission other than the power rollers is the same as the conventional one, so it will not be shown in the figures.

[0026] FIG. 1 is a cross-sectional view showing a power roller 40 of a double-cavity toroidal type continuously variable transmission according to this embodiment. As shown in FIG. 1, the power roller 40 includes a power roller inner ring 55 and a power roller outer ring 60 . The power roller inner ring 55 is sandwiched between the input side disc (first disc) 2 and the output side disc (second disc) 3 (see Figure 3), and has a large end face 55a facing the power roller outer ring 60, a small end face 55b facing the opposite side to the power roller outer ring 60 and having a smaller diameter than the large end face 55a, and a traction surface 55c formed by a curved surface that is provided between the large end face 55a and small end face 55b and is sandwiched between the two discs 2, 3 (see Figure 3).

[0027] In addition, an axial hole 58 is provided in the radial center of the power roller inner ring 55, extending in the axial direction of the power roller inner ring 55 (vertical direction in FIG. 1). The axial hole 58 is formed in a substantially cylindrical surface shape with the rotation axis of the power roller inner ring 55 as its axis, and the base end (lower end in FIG. 1) of the axial hole 58 opens in the center of the large end face 55a facing the power roller outer ring 60. In addition, the tip end (upper end in FIG. 1) of the axial hole 58 does not open to the small end face 55b of the power roller inner ring 55, but has a bottom surface 58a. In addition, the large end face 55a and the small end face 55b of the power roller inner ring 55 are flat surfaces perpendicular to the axis of the axial hole 58.

[0028] The power roller outer ring 60 has a disk-shaped outer ring body 61 and support shafts 62, 63 that are provided integrally with this outer ring body 61. The support shaft 62 is erected coaxially with the shaft hole 58 on the inner end surface of the outer ring body 61 that faces the power roller inner ring 55. The support shaft 62 is inserted into the shaft hole 58, and a gap is provided between the tip surface of the support shaft 62 and a bottom surface 58a of the shaft hole 58. The support shaft 63 is erected eccentrically with respect to the support shaft 62 and parallel to the support shaft 62 on the outer end surface of the outer ring body 61 facing away from the power roller inner ring 55. This support shaft 63 is adapted to be inserted into the circular hole 21 (see FIG. 4) provided in the support plate portion 16 of the trunnion 15.

[0029] Further, a thrust rolling bearing 71 is provided between the power roller inner ring 55 and the power roller outer ring 60. The thrust rolling bearing 71 allows the rotation of the power roller inner ring 55 while supporting the thrust load applied to the power roller inner ring 55, and includes a plurality of balls (rolling elements) 71a that roll on an inner ring raceway (bearing groove) 55g provided on the large end face 55a of the power roller inner ring 55 and an outer ring raceway (bearing groove) 60g provided on the inner end face of the outer ring body 61 of the power roller outer ring 60, and an annular cage 71b that holds the balls 71a so that they can roll.

[0030] A radial needle bearing (roller bearing) 72 is provided between the inner peripheral surface of the shaft hole 58 of the power roller inner ring 55 and the outer peripheral surface of the support shaft 62 of the power roller outer ring 60, and the radial needle bearing 72 enables the power roller inner ring 55 to rotate around the support shaft 62. The radial needle bearing 72 has a plurality of cylindrical rollers 72a arranged at predetermined intervals in the circumferential direction of the support shaft 62 and a cylindrical retainer 72b that holds the plurality of rollers 72a so that they can roll, and the rollers 72a are respectively arranged in a plurality of pockets provided at predetermined intervals in the circumferential direction on the outer peripheral wall of the retainer 72b.

[0031] Further, an oil hole 62a extending in the axial direction is provided in the center of the support shaft 62, opening at the tip end face of the support shaft 62. An introduction hole 66 for introducing lubricating oil into the oil hole 62a is provided at the bottom of the oil hole 62a, penetrating the outer ring body 61 in the thickness direction. Lubricating oil is supplied to this introduction hole 66 from an oil passage (not shown) provided in the trunnion 15 (see FIG. 4). Further, a plurality of discharge holes 62b are provided at a predetermined interval in the circumferential direction on the outer peripheral surface of the bottom of the oil hole 62a, and the discharge holes 62b are adapted to discharge the lubricating oil supplied to the oil hole 62a radially outward from the support shaft 62. The lubricating oil discharged from the discharge holes 62b is adapted to be supplied to the thrust rolling bearing 71 arranged on the outer side thereof. In addition, the lubricating oil supplied to the oil hole 62a flows radially outward at the tip opening of the oil hole 62a and is supplied to the radial needle bearing 72, and then passes through the radial needle bearing 72 and is supplied to the thrust rolling bearing 71.

[0032] 2, in this embodiment, as described above, the power roller inner ring 55 has a traction surface 55c having an arc-shaped cross section on the outer peripheral surface, and has a step surface 55s located radially inward from an extension surface 55e of the traction surface 55c on the outer diameter portion 55d, which serves as a machining reference for at least the traction surface 55c. The outer diameter portion 55d is a portion that constitutes the outer diameter on the large end surface 55a side of the power roller inner ring 55. In addition, since the traction surface 55c is formed of a spherical surface with a single R (radius), the extension surface 55e is a spherical surface that is a continuous extension of the R shape (spherical surface) of this single R from the traction surface 55c. This extended spherical surface is indicated by an imaginary two-dot chain line. The step surface 55s is formed of a cylindrical surface with the rotation axis of the power roller inner ring 55 as its axis.

[0033] The traction surface 55c of the power roller inner ring 55 is ultra-finished by the grinding wheel gw. The grinding wheel gw oscillates between the large end face 55a side and the small end face 55b side while sliding along the traction surface 55c. In this case, if the step surface 55s is not provided on the outer diameter portion 55d as in the conventional case and a straight reference surface is provided, when the grinding wheel gw goes over the end of the finishing surface of the traction surface 55c, it will interfere with the reference surface that serves as a reference in post-processing.

[0034] However, in this embodiment, the outer diameter portion 55d of the power roller inner ring 55 has at least the step surface 55s that serves as the processing reference for the traction surface 55c, so even if the grinding wheel gw goes over the finished surface edge of the traction surface 55c, it will not interfere with the step surface 55s that serves as the reference in post-processing. Therefore, since interference of the grinding wheel gw in the super-finishing of the traction surface 55c of the power roller inner ring 55 can be avoided, the traction surface can be super-finished to a portion that satisfies the design specified value, the super-finishing of the traction surface 55c can be easily performed, and the step surface 55s can ensure the processing reference of the required width on the outer diameter portion 55d that serves as the reference in post-processing. Furthermore, using this step surface 55s as a machining reference, in addition to super-finishing the traction surface 55 of the power roller inner ring 55, the shaft hole 58 and the bearing groove 55g of the power roller inner ring 55 can be finished.

[0035] In this embodiment, an example has been described in which the power roller outer ring 60 has eccentric support shafts 62, 63, but the present invention can also be applied to a case in which a support shaft that rotatably supports the power roller inner ring 55 is provided coaxially with the power roller outer ring 60 in the center of the power roller outer ring 60. The present invention can also be applied to a single-cavity half-toroidal type continuously variable transmission. [Explanation of symbols]

[0036] 2 Input disk (first disk) 3 Output disk (second disk) 55 Power roller inner ring (power roller) 55c traction surface 55d outer diameter 55e extension surface 55s step surface 60 Power roller outer ring

Claims

1. a first disk and a second disk arranged concentrically and rotatably with their respective inner surfaces facing each other; a power roller sandwiched between the first disc and the second disc, and a traction drive is performed by the first disc, the second disc and the power roller, The power roller has a traction surface having an arc-shaped cross section on its outer circumferential surface, and a stepped surface on its outer diameter portion, the stepped surface being located radially inward from an extension of the traction surface and serving as a machining reference for at least the traction surface.

2. 2. The toroidal type continuously variable transmission according to claim 1, wherein the step surface is formed by a cylindrical surface having an axis coincident with the rotation axis of the power roller.

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