Toroidal type continuously variable transmission

Abstract

To provide a toroidal type continuously variable transmission capable of securing an effective range of a traction surface, and capable of reducing a processing cost of a reference surface.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 2 and the second disk 3 and the power roller 40. 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 a round shape of the traction surface 55c reaches an outside diameter end 55e of the inner ring 55 of the power roller.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). As described above, the power roller is sandwiched between two discs (an input disc and an output disc), and the speed is changed by tilting the trunnion that rotatably supports the power roller. In a toroidal type continuously variable transmission, in order to improve the speed changing function, it is necessary to increase the dimensions of the power roller and disk in order to expand the effective range of the traction surface of the power roller (inner ring). In addition, the traction surface, shaft hole (hole into which the support shaft for rotatably supporting the power roller is inserted) and bearing groove (groove into which the thrust bearing for rotatably supporting the power roller is inserted) are formed in post-processing. For this purpose, the outer diameter portion (part that constitutes the outer diameter on the large end face side of the power roller (inner ring)) is processed to form a jig attachment reference surface for coaxial processing on the outer diameter portion. [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, there are size and weight limitations for vehicles and aircraft in which toroidal-type continuously variable transmissions are installed, and the dimensions of the power rollers and disks cannot be easily increased. Instead, the structure and shape must enable the gear ratio to be expanded without exceeding these limitations. Furthermore, since the reference surfaces for post-machining the traction surfaces, shaft holes, and bearing grooves are formed on the outer diameter portion, the machining costs for these reference surfaces lead to high costs.

[0018] The present invention has been made in consideration of the above circumstances, and aims to provide a toroidal-type continuously variable transmission that can ensure the effective range of the traction surface while reducing the processing costs of the reference surface. [Means for solving the problem]

[0019] 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 that 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 arcuate cross section on its outer circumferential surface, The R-shape of the traction surface extends to the outer diameter end of the power roller.

[0020] Here, the "R-shape of the traction surface" refers to the spherical shape that forms the traction surface. Moreover, the term "outer diameter end portion" refers to the end portion (edge ​​portion) of the outer diameter portion that constitutes the outer diameter on the large end face side of the power roller (inner ring).

[0021] In the present invention, the R-shape of the traction surface of the power roller reaches the outer diameter end of the power roller, so that the effective range of the traction surface can be secured within the limited range of the size of the power roller. In addition, since the machining reference points for the traction surface, shaft hole, and bearing groove can be formed by post-processing, the R-shaped portion reaching the outer diameter end of the power roller can be used as the machining reference point, which reduces the processing costs for the machining reference points.

[0022] In the above-mentioned configuration of the present invention, the R-shaped portion reaching the outer diameter end portion may serve as a machining reference for at least one of a traction surface, a bearing groove, and a shaft hole of the power roller.

[0023] According to this configuration, at least one of the traction surface, the bearing groove, and the shaft hole of the power roller can be finish-machined using the R-shaped portion of the traction surface that reaches the outer diameter end of the power roller as a machining reference. Effect of the Invention

[0024] According to the present invention, it is possible to ensure the effective range of the traction surface and reduce the processing cost of the reference surface. [Brief description of the drawings]

[0025] [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. [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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the toroidal type continuously variable transmission of this embodiment differs from the conventional toroidal type continuously variable transmission shown in Figures 3 and 4 mainly in the configuration of the power rollers, so this point will be described below, and other identical components will be given the same reference numerals and their description may be omitted or simplified.

[0027] 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).

[0028] 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.

[0029] 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. 3) provided in the support plate portion 16 of the trunnion 15.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 its outer peripheral surface, and the R-shape of the traction surface 55c reaches the outer diameter end 55e of the outer diameter portion 55d of the power roller inner ring 55. The outer diameter portion 55d is a portion that constitutes the outer diameter on the large end face 55a side of the power roller inner ring 55, and the R-shape of the traction surface 55c extends to the outer diameter end 55e of this outer diameter portion 55d, i.e., the edge portion on the large end face 55a side. The traction surface 55c has an arc-shaped cross section and is formed of a single R-surface from the small end face 55b to the large end face 55a.

[0034] The traction surface 55c of the power roller inner ring 55 is super-finished by the grinding wheel gw. The grinding wheel gw oscillates between the large end face 55a and the small end face 55b while sliding along the traction surface 55c. In this case, if a straight reference surface is provided on the outer diameter portion 55d as in the conventional case, 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.

[0035] However, in this embodiment, the R-shape of the traction surface 55c reaches the outer diameter end 55e of the power roller inner ring 55, and the R-shape portion reaching the outer diameter end 55e serves as the machining reference. Therefore, the effective range of the traction surface 55c can be ensured within the limited range of the size of the power roller inner ring 55. In addition, since the machining reference points for the traction surface 55c, the shaft hole 58 and the bearing groove 55g can be formed by post-processing, using the R-shaped portion reaching the outer diameter end of the power roller inner ring 55 as the machining reference point, the processing costs for the machining reference point can be reduced.

[0036] In addition, in this embodiment, the R-shaped portion of the traction surface 55c that reaches the outer diameter end portion 55e serves as the machining reference for the traction surface 55c, shaft hole 58, and bearing groove 55g of the power roller inner ring 55, so that the traction surface 55c, shaft hole 58, and bearing groove 55g of the power roller inner ring 55 can be finish-machined using this as the machining reference.

[0037] 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]

[0038] 2 Input disk (first disk) 3 Output disk (second disk) 55 Power roller inner ring (power roller) 55c traction surface 55g bearing groove 55e Outer diameter end 58 Shaft hole 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, wherein the first disc, the second disc and the power roller perform traction drive, The power roller has a traction surface having an arcuate cross section on its outer circumferential surface, 2. A toroidal type continuously variable transmission, wherein the R-shape of the traction surface reaches an outer diameter end of the power roller.

2. 2. The toroidal type continuously variable transmission according to claim 1, wherein the R-shaped portion that reaches the outer diameter end portion serves as a machining reference for at least one of the traction surface, the bearing groove, and the shaft hole of the power roller.

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