JP2514810B2 - V-belt type automatic transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a variable-diameter pulley of a V-belt type automatic transmission.

[Conventional technology and its problems]

Conventionally, in a V-belt type automatic transmission, a pulley of a V-belt is composed of a fixed sheave and a movable sheave that moves forward and backward in the axial direction, and both sheaves come close to or separate from each other depending on the magnitude of the V-belt tension. Then, when the effective diameter is changed to a large or small value and the speed of the drive shaft drops below a predetermined value,
The clutch is commonly used by expanding the width of the V-belt so as to cut off the transmission of power. Further, when the clutch is cut off, slippage may occur between the V-belt and the drive shaft and wear may occur. Therefore, in order to prevent this, a ball bearing is provided between both sheaves ( For example, Japanese Utility Model Publication No. 50-35966).

In such a case, since the minimum diameter of the pulley is limited by the size of the ball bearing, there is a problem that the gear ratio cannot be changed greatly.

[Outline of Object of Invention and Means for Solving Problem]

An object of the present invention is to solve the above problems, to prevent damage to the V-belt, and to obtain a V-belt automatic transmission capable of greatly changing the gear ratio. The drive pulley drives the drive shaft. A fixed diameter sheave fixed to one end of the cylindrical boss portion and a movable sheave rotatably supported on the other end side of the boss portion so as to be movable back and forth with respect to the fixed sheave, A cylindrical bush is rotatably and axially slidably fitted to the outer peripheral portion of the boss portion between the fixed sheave and the movable sheave, and the bush is attached to the fixed sheave and the movable sheave. Is formed in the shaft hole of the movable sheave, and the bush is fitted in the shaft hole of the movable sheave rotatably and slidably in the axial direction. Set shorter than the total length of the bush By one end of bushing is characterized in that the other end of the bushing in a state fitted in the shaft hole of the movable Sheep has a structure that protrudes from the movable sheave toward the fixed sheave side.

[Action]

When the clutch is cut off by greatly expanding the space between the fixed sheave and the movable sheave, the V-belt is supported by the small diameter bush protruding from the movable sheave to the fixed sheave side. The diameter of both sheaves can be made smaller than that of the conventional one using a bearing, and thus a large gear ratio can be obtained without increasing the maximum diameter of the sheaves.

〔Example〕

Hereinafter, the present invention will be described with reference to the illustrated embodiments.
In the figure, 1 is a drive pulley of a V-belt type automatic transmission,
The drive pulley 1 is made by casting an aluminum alloy, and is composed of a fixed sheave 2 and a movable sheave 3 that face each other with a dish-shaped surface. That is, the fixed sheave 2 is screwed onto the boss portion 2a fitted to the drive shaft 4 and the lock nut 2b.
It is prevented from loosening. Also, this fixed sheave 2
A shaft hole 2c for accommodating a bush, which will be described later, is provided in the shaft center part of
Are formed. The axial hole 2c is formed so that its axial depth is shorter than the entire length of the bush. Further, the movable sheave 3 is slidably supported on the boss portion 2a through a bush 3b made of a copper alloy which is slightly longer than the depth of the shaft hole 3a which is loosely fitted in the shaft hole 3a. The effective diameter of the V-belt 5 wound around between the fixed sheave 2 and the fixed sheave 2 is changed in size.

As shown in FIG. 1, the bush 3b projects from the movable sheave 3 toward the fixed sheave 2 when fitted into the shaft hole 3a of the movable sheave 3. Therefore, when the movable sheave 3 approaches the fixed sheave 2, the bush 3b also moves in the same direction, and the protruding end portion of the bush 3b is inserted into the shaft hole 2c of the fixed sheave 2.

Three guide bars 3c are provided on the rear surface of the movable sheave 3, and an aluminum alloy auxiliary frame 6 pivotally supported by the small diameter portion of the boss 2a is connected to the other end of the guide bar 3c by bolts 6a. Are integrated. Reference numeral 3d is a core portion that constitutes the guide bar 3c, and the outer periphery thereof is covered with a synthetic resin tube 3e.
A concave groove 3f is provided on the back surface of the movable sheave 3 in the middle of each guide bar 3c, and the centrifugal weight 7 is supported by its supporting shaft 7a.

Reference numeral 8 denotes a pressure receiving member arranged between the movable sheave 3 and the auxiliary frame 6. The pressure receiving member 8 is screwed to the small diameter portion of the boss portion 2a, and the movable sheave 3 is constantly fixed by the return spring 9 on the back surface. It is urged in a direction to separate it from the sheave 2. Reference numeral 8a denotes a sliding member made of synthetic resin, which is attached to the pressure receiving member 8 with a bolt 8b, and abuts against the centrifugal weight 7 to support the pushing force thereof.

Next, the operation of this embodiment will be described. While the drive shaft 4 is operated at a lower speed than planned, the centrifugal weight 7 rotates outward and comes into contact with the sliding friction member 8a. The movable sheave 3 is at the left end position as shown in FIG.
Further retreat is restricted by the pressure receiving member 8.
Therefore, the V-belt 5 is released from the restraint of both sheaves 2 and 3 and is supported by the bush 3b. Since the bush 3b is not fixed to the movable sheave 3 or the boss portion 2a, even if the drive shaft 4 rotates due to friction with the V-belt 5, the bush 3b maintains a stopped state. There is no unnecessary friction and no wear.

When the speed of the drive shaft 4 is increased in order to start traveling of the vehicle, the centrifugal weight 7 further swings outward, and the rubbing member 8a
The pressure-receiving member 8 is strongly pressed via and the movable sheave 3 is moved to the right in the figure by the reaction force. By this action, the V-belt 5 is pinched between the fixed sheave 2 and the movable sheave 3, and power is transmitted by the friction. Also, the drive shaft 4
As the speed increases, the movable sheave 3
Further approaches the fixed sheave 2 side to increase the effective diameter of the drive pulley 1 and reduce the reduction ratio of the transmission to increase the vehicle speed.

When the movable sheave 3 moves to the fixed sheave 2 side as described above, the bush 3b moves together with the movable sheave 3 in the same direction. At this time, since the bush 3b slides on the outer peripheral surface of the boss portion 2a, foreign matter such as abrasion powder of the V-belt 5 is prevented.
When attached to the outer peripheral surface of 2a, the attached matter is scraped off by the edge of the bush 3b on the fixed sheave 2 side.

〔The invention's effect〕

As described above, according to the present invention, the drive pulley is fixed to one end of the cylindrical boss portion driven by the drive shaft, and
The other end of the boss portion is configured to have a variable diameter with a movable sheave that is axially supported so as to be movable back and forth with respect to the fixed sheave, and the fixed sheave and the movable sheave are the outer peripheral portion of the boss portion. A cylindrical bush is rotatably and slidably fitted in the axial direction at a portion between the two, and a shaft hole for accommodating the bush is formed in the fixed sheave and the movable sheave to form a shaft hole of the movable sheave. One end of the bush is moved by fitting the bush in a rotatable and axially slidable manner, and setting the axial depth of each shaft hole of the fixed sheave and the movable sheave to be shorter than the entire length of the bush. Since the other end of the bush protrudes from the movable sheave to the fixed sheave side while being fitted in the shaft hole of the sheave, the V belt 5 is driven when the speed of the drive pulley is low and power transmission is cut off. Bushi supported on the shaft To be supported, it is not caused galling between the drive shaft. Further, since the bush has a small diameter, there is an effect that it is possible to set a large gear ratio without increasing the maximum diameter of both sheaves.

Further, when the movable sheave moves toward the fixed sheave side as the rotation increases, the bush also moves in the same direction while slidingly contacting the boss portion, so that the V attached to the portion between the fixed sheave and the movable sheave on the outer peripheral surface of the boss portion. Belt abrasion powder and the like can be scraped off by the axial end portion of the bush. That is, since the surface on which the bush rotates (the outer peripheral surface of the boss portion) is cleaned by shifting from the low rotation state to the high rotation state, the rotation speed subsequently decreases and the V belt contacts the bush. The bush can rotate smoothly with respect to the boss when it reaches the limit. In other words, the bush does not stick to the boss portion due to the adhesion of foreign matter to the rotating portion.

Furthermore, since it is the fixed sheave and the movable sheave that regulate the axial movement of the bush, no special member is required to regulate the axial movement. Therefore, the structure for supporting the bush can be simple.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a sectional view of a drive pulley, and FIG. 2 is a partially cutaway front view. 2 ... Fixed sheave, 2a ... Boss part, 3 ... Movable sheave,
3b ... Bushiyu, 5 ... V belt, 7 ... centrifugal weight.

Claims (3)

(57) [Claims] 1. A fixed sheave in which a drive pulley is fixed to one end of a cylindrical boss portion driven by a drive shaft, and a shaft support for allowing the drive pulley to move forward and backward with respect to the fixed sheave on the other end side of the boss portion. The movable bush is configured to have a variable diameter, and a cylindrical bush is rotatably and axially slidably fitted on the outer peripheral portion of the boss portion between the fixed sheave and the movable sheave. In addition, the fixed sheave and the movable sheave are formed with an axial hole for accommodating the bush, and the bush is rotatably and axially slidably fitted into the axial hole of the movable sheave. By setting the axial depth of each of the shaft holes to be shorter than the total length of the bush, the other end of the bush is fixed to the fixed sheave while the other end of the bush is fitted in the shaft hole of the movable sheave. The structure that protrudes to the side V-belt type automatic transmission according to claim. 2. The V-belt type automatic transmission according to claim 1, wherein the movable sheave is cast from an aluminum alloy and the bush is made from a copper alloy. 3. The movable sheave is configured to slide according to the swing of a centrifugal weight pivotally attached to the back surface.
V-belt type automatic transmission according to the item.