JP4045981B2 - Toroidal continuously variable transmission - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a toroidal continuously variable transmission.
[0002]
[Prior art]
In the toroidal type continuously variable transmission, by changing the tilt angle of a pair of power rollers sandwiched between the input disk and the output disk, the ratio of the rotational speed of the input disk to the rotational speed of the output disk, that is, The gear ratio is changed steplessly. Each power roller is supported by a trunnion, and when the trunnion is displaced in the axial direction by a hydraulic actuator, the inclination of the power roller changes in accordance with the displacement of the trunnion.
[0003]
In the toroidal type continuously variable transmission, it is necessary to apply a thrust load to the input disk and the output disk in order to sandwich the power roller between the input disk and the output disk. In general, a thrust load proportional to the torque input to the transmission is generated by a loading cam and applied to the input disk and the output disk.
[0004]
Further, since the loading cam does not generate a thrust load when the torque input to the transmission is zero, it is necessary to provide a preloading mechanism separately from the loading cam and apply a predetermined preload to the input disk and the output disk. In Patent Document 1, the preloading mechanism is configured by a disc spring 9 sandwiched between a loading nut 30 fastened to an end of the transmission input shaft 20 and the input disk 1 as shown in FIG. Yes.
[0005]
[Patent Document 1]
JP 2000-74167 A
[0006]
[Problems to be solved by the invention]
In Patent Document 1, the preload is determined according to the initial compression amount of the disc spring 9, and the adjustment of the compression amount is performed between the step portion 21 formed on the outer periphery of the input shaft 20 and the loading nut 30. This is done by adjusting the axial length of. If the axial length of the collar 40 is shortened, the distance between the input disk 1 and the loading nut 30 is shortened, the amount of compression of the disc spring 9 is increased, and the preload can be increased. In order to reduce the preload, the length of the collar 40 in the axial direction may be increased.
[0007]
However, in such a configuration, since the tightening force of the loading nut 30 acts on the step portion 21 via the collar 40, stress concentration occurs in the step portion 21. In order to reduce the maximum stress, it is necessary to increase the radius of curvature of the stepped portion 21, but in order to increase the radius of curvature, the stepped portion of the stepped portion 21 needs to be increased. In this case, the diameter of the input shaft 20 is increased. This increases the size of the transmission.
[0008]
The present invention has been made in view of such technical problems of the prior art, and an object thereof is to downsize a transmission while avoiding stress concentration.
[0009]
[Means for solving problems]
The loading nut is formed into a cylindrical shape with a bottom, and a threaded portion is formed on the inner periphery of the threaded portion of the input shaft, and an adjustment member is interposed between the end surface of the transmission input shaft and the bottom of the loading nut. The preload is adjusted by adjusting the axial length of the member.
[0010]
[Action and effect]
According to the above configuration, the preload can be easily adjusted as in the prior art. In addition, the tightening force of the loading nut acts almost perpendicularly to the end face of the input shaft via the adjusting member, and does not act on the step portion provided in the middle of the input shaft as in the prior art, thus avoiding stress concentration. be able to. If the stress concentration can be avoided, the required mechanical strength can be reduced, and the transmission can be miniaturized by reducing the diameter of the input shaft.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 shows a cross section of a toroidal continuously variable transmission according to the present invention. The toroidal continuously variable transmission includes a first toroidal unit 11 and a second toroidal unit 12. The first toroidal unit 11 has a pair of power rollers 3 and 3 sandwiched between an input disk 1a and an output disk 2a. Similarly, the second toroidal unit 12 includes an input disk 1b and an output disk 2b. A pair of power rollers 3 and 3 are sandwiched between them.
[0013]
The input disk 1a and the input disk 1b are coupled to the input shaft 20 via ball splines 13 and 13, respectively, and rotate synchronously. The output disk 2a and the output disk 2b are coupled to the output gear 10. The input shaft 20 passes through the output gear 10, and the output disks 2 a and 2 b rotate relative to the input shaft 20.
[0014]
Each power roller 3 is supported by a trunnion 4. When a hydraulic actuator (not shown) displaces each trunnion 4 in the vertical direction in the figure, each power roller 3 is tilted, the contact radius with the input / output disk is changed, and the gear ratio is continuously changed. The trunnions 4 and 4 facing each other are connected by an upper link 5 at the upper end and a lower link 6 at the lower end, and are displaced in directions opposite to each other.
[0015]
The oil film between the disks 1a, 1b, 2a, 2b and the power roller 3 becomes glassy under high pressure. The driving force is transmitted by the shear force of the oil film. On the left side of the input disk 1a in the figure, there is provided a loading cam 8 that generates a thrust load corresponding to the input torque and applies it to the disks 1a, 2a, 1b, and 2b.
[0016]
On the other hand, on the right side of the input disk 1b in the figure, a preloading mechanism 16 is provided that applies a load (preload) necessary for pinching the power roller 3 even when the input torque is small or zero.
[0017]
FIG. 2 shows a schematic configuration of the preloading mechanism 16, and the alternate long and short dash line in the figure indicates the center line of the input shaft 20.
[0018]
A screw portion 20 s is formed on the outer periphery of the end portion of the input shaft 20, and is screwed into a screw portion 30 s formed on the inner periphery of the loading nut 30. The center of the input shaft 20 is a cavity through which lubricating and cooling oil flows.
[0019]
The loading nut 30 has a bottomed cylindrical shape with an opening on the left side in the drawing, and a threaded portion 30s is formed on the inner periphery from the opening end 30a over a predetermined length. A cylindrical collar 40 (adjustment member) is accommodated on the inner periphery where the screw portion close to the bottom portion 30c is not formed. Further, a hole 30 d extending in the axial direction is opened in the bottom portion 30 c of the loading nut 30, and this hole constitutes an oil passage communicating with the oil passage 20 d inside the input shaft 20 together with the center hole 40 d of the collar 40. The loading nut 30 is supported by the transmission case 70 via a roller bearing 31.
[0020]
When the loading nut 30 is screwed into the input shaft 20 from the right direction in the figure, the tightening force of the loading nut 30 acts on the end surface 20a of the input shaft 20 through the collar 40 substantially perpendicularly. If the axial length of the collar 40 is adjusted, the screwing amount of the loading nut 30 changes, and the distance between the loading nut 30 and the input disk 1b can be adjusted.
[0021]
A disc spring 9 (elastic member) is interposed between the opening side end face 30b of the loading nut 30 and the input disk 1b, and the preloading mechanism 16 has a restoring force when the disc spring 9 is compressed. By giving a preload.
[0022]
A cylindrical spacer 50 is interposed between the opening side end face 30a of the loading nut 30 and the input disk 1b. The axial length L of the spacer 50 is such that even if the input disk 1b is displaced to the right in the drawing according to the change in the tilt angle of the power roller 3, the spacer 50 is compressed before the compression amount of the disc spring 9 exceeds a predetermined amount. Is adjusted so that the compression amount does not always exceed a predetermined value.
[0023]
A plurality of axially extending grooves 23 are formed on the outer periphery of the enlarged diameter portion 22 forming the stepped portion 21 of the input shaft 20, and a plurality of spheres 24 are accommodated in the groove 23. These constitute a ball spline 13 that supports the input disk 1 on the input shaft 20 so as to be rotatable and movable in the axial direction, and a C-ring 25 is attached so that the sphere 24 does not fall off.
[0024]
Therefore, according to the above configuration, when the tilt angle of the power roller 3 corresponds to the minimum speed ratio and the input torque is zero, the input disk 1b is pushed leftward in the figure by the restoring force of the disc spring 9. As a result, the power roller 3 (not shown) can be sandwiched between the input disk 1b and the output disk 2b. When the speed ratio is increased by tilting the power roller 3, the input disk 1b is displaced in the right direction in the figure. However, since the maximum compression amount of the disc spring 9 is limited by the spacer 50, the disc spring 9 is compressed. There is no compression beyond the limit.
[0025]
In particular, since a collar 40 (adjustment member) having an axial length is interposed between the end face 20a of the input shaft 20 and the bottom 30c of the loading nut 30, the loading can be achieved by adjusting the axial length of the collar 40. By changing the screwing amount of the nut 30, the initial compression amount of the disc spring 9 can be adjusted, and the preload can be easily adjusted.
[0026]
Further, the tightening force of the loading nut 30 acts on the end surface 20a of the input shaft 20 via the collar 40, and the stress in the axial direction acts on the end surface 20a almost evenly, so that no stress concentration occurs on the end surface 20a. . Further, since the tightening force of the loading nut 30 does not directly act on the step portion 21 formed on the outer periphery of the input shaft 20, no stress concentration occurs on the step portion 21.
[0027]
Further, since it is not necessary to support the force acting in the axial direction at the step portion 21, it is not necessary to provide a surface perpendicular to the axial direction on the step portion 21, and the step portion without increasing the diameter of the input shaft 20. The radius of curvature of 21 can be increased, and the stress concentration can be further suppressed.
[0028]
Further, since the loading nut 30 is supported on the transmission case 70 via the bearing 31, even if a relatively long screw portion 30s is formed on the inner periphery of the loading nut 30, the shaft length of the input shaft 20 can be increased. There is no need to lengthen the transmission, and the transmission can be downsized.
[0029]
FIG. 3 shows a second embodiment of the present invention.
[0030]
The second embodiment is a partial modification of the first embodiment. 2 is different from the first embodiment shown in FIG. 2 in that the enlarged diameter portion 22 of the input shaft 20 is eliminated and the stepped portion 21 of the input shaft 20 is eliminated. Other configurations are the same as those of the first embodiment.
[0031]
This is because the collar 40 is interposed between the end face of the input shaft 20 and the loading nut 30, and the collar is interposed between the loading nut 30 and the stepped portion 21 of the input shaft 20, which has been conventionally required. Therefore, the step portion 21 and the diameter-enlarged portion 22 that are necessary for supporting the collar are eliminated.
[0032]
Thereby, the diameter of the input shaft 20 can be reduced, and the transmission can be further reduced. Since the sphere 24 of the ball spline 13 is prevented from falling off by the groove 23 itself, the C-ring for preventing the dropping is also unnecessary.
[0033]
FIG. 4 shows a third embodiment of the present invention.
[0034]
In the third embodiment, a screw portion 20 s is formed on the outer periphery of the end portion of the input shaft 20, and a screw portion 30 s that is screwed to the loading nut 30 is formed in the middle of the inner periphery of the loading nut 30. This is different from the previous embodiment in that the inner circumference of this is in contact with the outer circumference of the input shaft 20 (a so-called inlay type). The ball spline 13 may or may not have an enlarged diameter portion.
[0035]
The loading nut 30 is formed on the input shaft 20 by forming the screw portion 30 s of the loading nut 30 so as to avoid the opening end 30 b and supporting the opening end 30 b of the loading nut 30 on the outer periphery of the input shaft 20. Accordingly, the movement of the loading nut 30 being inclined with respect to the central axis of the input shaft 20 is restricted. As a result, the burden on the bearing 31 that supports the loading nut 30 can be reduced compared to the previous embodiment, and the bearing 31 can be downsized to further reduce the transmission.
[0036]
The embodiment of the present invention has been described above. However, the above embodiment is merely an example of a transmission to which the present invention is applied, and the scope of the present invention is limited to the configuration of the above embodiment. Absent.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a toroidal continuously variable transmission according to the present invention.
FIG. 2 is a schematic configuration diagram of a preloading mechanism.
FIG. 3 is a diagram showing a second embodiment of the present invention.
FIG. 4 is a diagram showing a third embodiment of the present invention.
FIG. 5 is a view showing a conventional preloading mechanism.
[Explanation of symbols]
1a, 1b Input disk 2a, 2b Output disk 3 Power roller 9 Belleville spring (elastic member)
13 Ball spline 16 Preloading mechanism 20 Input shaft 20a Input shaft end surface 20s Screw portion 21 Step portion 22 Expanded portion 24 Ball 30 Loading nut 30a Loading nut opening end 30b Loading nut opening end 30d Loading nut bottom portion 30s Screw Part 31 Bearing 40 Color (Adjustment member)
50 Spacer 70 Transmission case

Claims (3)

An input shaft having a threaded portion formed on the outer periphery;
An input disk supported on the input shaft so as to be rotatable and slidable in the axial direction;
An output disk disposed opposite the input disk;
A power roller sandwiched between the input disk and the output disk;
A loading nut screwed into the threaded portion of the input shaft;
A preload for holding the power roller between the input disk and the output disk when the input torque to the transmission is zero by the restoring force of an elastic member interposed between the input disk and the loading nut. A preloading mechanism applied to the input disk;
Toroidal continuously variable transmission with
The loading nut is formed into a cylindrical shape with a bottom, and a screw portion that is screwed to the screw portion of the input shaft is formed on the inner periphery thereof,
An adjustment member is interposed between the end surface of the input shaft and the bottom of the loading nut,
A toroidal continuously variable transmission configured to adjust the preload by adjusting an axial length of the adjusting member. The toroidal continuously variable transmission according to claim 1, wherein the loading nut is supported by a bearing with respect to a transmission case of the transmission. The thread portion of the loading nut is formed so as to avoid the opening end portion, and the opening end portion of the loading nut is configured to be supported on the outer periphery of the input shaft. Toroidal-type continuously variable transmission.

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