JPS60184757A - Torque cam device in v-belt type automatic transmission - Google Patents

Abstract

PURPOSE:To increase the durability of a shoe to stabilize the function thereof, by forming the cam surface of a torque cam in a cylindrical convex curved surface shape, by forming the contact surface of the shoe made in contact with the cam surface, in a cylindrical concave curved surface shape having the same diameter as that of the cam surface, and by swingably journalling the shoe. CONSTITUTION:A drive shoe 7 for a torque cam is swingably supported by means of a pin 8 to the front end of a stay projected from the rear surface of a movable face 2. The torque cam 9 is secured to a driven shaft 3 so that it is positioned in front of the drive shoe in the rotational direction of the latter, and is made in contact with the drive shoe. The cam surface 9a of the torque cam 9 is formed in the shape of a convex curved surface which constitutes a part of cylinder 10 parallel with the axis of the pin 8, so that the further the distance from the movable face 2a the smaller the inclination angle of the cam surface 9a becomes. Meanwhile the contact surface 7a of the drive shoe 7 is formed in the shape of a concave curved surface identical with the shape of the cylinder 10 so that it may made in close contact with the cam surface 9a with no gap.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque cam device for a V-belt automatic transmission that detects the transmitted torque of a driven V-pulley to control a gear ratio.

In a V-belt automatic transmission, a V-pulley is configured with a fixed face and a movable face, and the effective diameter of the V-belt suspension is changed by adjusting the distance between the two faces. To control the movable face, the drive side uses the centrifugal force of the drive shaft, and the driven side uses a torque cam that responds to the load on the driven shaft. The torque cam has the function of moving closer to the inclined surface interposed between the movable face and the driven shaft to enlarge the suspension diameter of the V-belt and shift the V-belt to a low speed range. The inclination angle of the torque cam in a V-belt automatic transmission used in a small motorcycle or the like is generally set to be large in the low speed range and small in the high speed range. This is to prevent the engine from unnecessarily kicking down to the low speed range due to shock torque picked up by the drive wheels while driving at a constant speed in the high speed range, causing an unpleasant revving of the engine.

Incidentally, the general configuration of a torque cam is a combination of three rollers and a cam groove formed on a cylindrical surface, but the structure is complicated and the cylinder radius cannot be increased, so the transmitted torque value becomes large and the strength is unstable. There is. To improve this point, there is a torque cam that has a synthetic resin shoe in contact with a metal cam at a relatively large diameter position.This requires a small torque value, has excellent durability, and can be used without lubrication. , it also has the advantage of requiring fewer processing steps. However, as mentioned above, a torque cam that is set to have a small inclination in the high-speed range has a curved surface, so while there is no problem in the former case, in the latter case there is a line contact, which increases the surface area and reduces the wear of the engine. There are drawbacks that can easily occur.

SUMMARY OF THE INVENTION In view of the above drawbacks, an object of the present invention is to provide a torque cam device for a V-belt automatic transmission using a metal cam and a shoe that always maintains the same contact surface as the inclination angle changes. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings showing embodiments of the present invention will be explained in detail below. FIG. 1 is a rear view of the movable face of the driven V googly, FIG. 2 is a longitudinal side view of the same, and FIG. 3 is a side view of the torque cam.

The driven V-glue is composed of a fixed face 1 fixed to a driven shaft 3 and a movable face 2 rotatably and slidably supported, facing each other, with a V-belt 4 suspended between them. A spring 5 is brought into elastic contact with the movable face 2 from the back side, and acts to pinch the V-belt 4 and expand its suspension diameter.

A stay 6 is further provided on the back surface of the movable face 2 and is arranged on the same circumference in a protruding manner, and a drive shoe 7 of a torque cam is swingably supported at the tip of the stay 6 by a pin 8 . The axis of the bin 8 is set to be on a plane perpendicular to the driven axis 3. On the other hand, the torque cam 9 is fixed to the driven shaft 3 and located in front of the drive shoe 7 in the rotational direction, and comes into contact with the drive shoe 7. Cam surface 9m of torque cam 9
is formed into a convex curved surface forming part of a cylinder 10 parallel to the axis of the pin 8, and is set in such a shape that the angle of inclination decreases as it moves away from the movable face 2 in the axial direction. The contact surface 7a of the drive shoe 7 is formed by an attached synthetic resin lining 11, has the same concave curved surface as the cylinder 0, and comes into contact with the cam surface 9a without any gap.

The driven V pulley configured as described above operates as follows. The driving force of the V-belt 4 is transmitted half to the fixed face 1 and half to the movable face 2, and the torque of the movable face τ is transmitted to the driven shaft 3 via the stay 6, drive shoe 7, and torque cam 9. The torque transmitted between the drive shoe 7 and the torque cam 9 produces an axial component force due to the inclination of the cam surface 9a, and this component force is applied to the movable face 2 to pinch the V-belt 4. This force acts to expand the suspension diameter of the V-belt 4, increasing the reduction ratio of the transmission. In other words, it is shifted to the low speed range. Further, this force is proportional to the magnitude of the transmitted torque and is also related to the magnitude of the inclination angle of the cam surface 9a. The cam surface 9a has a large inclination angle in the low speed range (on the left side in the figure) and a small inclination angle in the high speed range, so that with the same transmitted torque, the force component is large in the low speed range, making it easier to shift. When driving at a constant speed at high speeds, there is no unnecessary kickdown and it is stable.

The drive shoe 7 is the cam surface 9 of the above-mentioned through torque cam 9.
The contact surface 7a and the cam surface 9a are formed into the same cylindrical uneven curved surface, and the drive shoe 7 can be oscillated by the pin 8. The contact surface 7a follows the change in the inclination angle of the cam surface 9a, and the two surfaces are in perfect contact in any range. Therefore, the surface pressure is small, the durability of the lining [1] is increased, and the sliding properties of the gold and synthetic resin without lubrication are maintained for a long time.

In addition, in the low speed range part and the high speed range part of the cam surface 9a,
A relative displacement occurs between the drive shoe 7 and the torque cam 9 in the circumferential direction, and the contact surface 7a and the cam surface 9a are relatively inclined in the circumferential direction. A slight inclination is absorbed by the gap between the bin 8 and the drive shoe 7. If the inclination is large, the axis of the bottle 8 and the drive shoe 7 should be made spherical, or the tip 6a aligned with the stay 6 as shown in FIG.
It is only necessary to make it possible to oscillate within a small range and absorb it. Alternatively, the radius of the contact surface 7a may be set slightly larger by twisting the cam surface 9a.

Further, the arrangement of the shoe and the cam may be reversed with respect to the drive side and the driven side.

As described above, in the torque cam device for a V-belt automatic transmission according to the present invention, the contact surfaces between the cam and the shoe are formed into a cylindrical concave curved surface and a convex curved surface with the same radius, and the shoe is capable of oscillating motion. For the cam surface whose inclination angle is gradually set smaller from the low speed range to the high speed range,
The shoe always makes contact over a wide area, creating less counterpressure and preventing wear, increasing the durability of the shoe and stabilizing its function. Since it can be installed at a position away from the center of the driven shaft on the back of the movable face, the transmitted torque is small and surface pressure can be further reduced, durability is further increased, and costs can be reduced because it requires no lubrication and can be configured with fewer machining steps. Moreover, it has the effect of improving the riding comfort of motorcycles and the like by preventing unpleasant kickdowns that occur unnecessarily during high-speed driving.

[Brief explanation of drawings]

FIG. 1 is a rear view of a movable face of a driven V pulley showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional side view of the same, and FIG. 3 is a plan view of the same torque cam. 1... Fixed face, 2... Movable face, 3...
-do') 7'n'1!11% 4...V belt, 6
... Stay 17... Drive shoe, 8... Pin, 9... Torque cam, 10... Cylinder, 11... Lining. Applicant's agent Shizuo Hatano Figure 1 Figure 2

Claims (1)

[Claims] A V-pulley is constructed by arranging a fixed face fixed to the driven shaft and a movable face rotatably and slidably supported on the same axis, and a torque cam is interposed between the movable face and the driven shaft, In this driven V pulley, which presses the movable face against the fixed face by the axial component of the torque transmitted to the torque cam, the cam surface of the torque cam is formed into a cylindrical convex curved surface, and the contact surface of the shoe that contacts this is formed into a cylindrical convex curved surface. A torque cam device for a V-belt automatic transmission, characterized in that it is formed into a cylindrical concave curved surface of the same diameter and is pivotably supported by a pin.