JPH06137390A - Belt tension regulating device - Google Patents

Abstract

PURPOSE:To shorten the height of a pulley arm and fabricate the assemblage of a press means in a device for producing a wedge effect by means of the press means for pressing a relatively included guide provided on the pulley arm and fulcrum shaft and a member engaged with the guide so that the turning movement of the pulley arm may be damped. CONSTITUTION:Parallel spline guides 10 are formed in the hole part 2 of a pulley arm 1 and a helical spline guide 11 is formed on a fulcrum shaft 6. A nut 12 is engaged with the spline guides 10, 11 to be pushed axially by a compression spring 13 disposed on the outside of the hole part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tension adjusting device used for adjusting the tension of a timing belt of an automobile engine.

[0002]

2. Description of the Related Art As a belt tension adjusting device of this type,
Conventionally, a structure in which the swing of the pulley arm is buffered by a hydraulic damper is known, but a structure using this hydraulic damper has a large number of parts due to a hydraulic seal structure, etc. There is a complication.

To address such a problem, the applicant of the present invention has proposed a device capable of exhibiting a large damper capacity by a mechanical structure in Japanese Patent Application No. 4-67390.

In this proposal, as shown in FIG. 5, a fulcrum shaft 33 fixed in a hole 32 provided in a pulley arm 31.
Are fitted to the fulcrum shaft 33 and the facing surface of the hole 32, and the splines 34 and 35 are inclined relative to each other in the axial direction.
And a compression spring 37 that axially presses the nut 36 and a nut 36 that engages with the splines 34 and 35 is provided between the fulcrum shaft 33 and the hole 32. Due to the pressing force and the wedge effect of both splines 34 and 35, the movement of the nut 36 in the axial direction is restricted and the rotation of the pulley arm 31 is buffered.

[0005]

However, in the device proposed above, the compression spring 37 for pressing the nut 36 is provided inside the hole 32 of the pulley arm 31 and is arranged in series with the nut 36. The axial length of the shaft 33 and the pulley arm 31 becomes large, which is an obstacle to downsizing.

Further, since the diameter of the compression spring 37 is restricted by the inner diameter of the hole 32 and the spring diameter and outer diameter cannot be freely expanded, there is a limit to the setting range of the thrust of the spring.

Further, a compression spring 37 for the nut 36
Since the pressing position of is on the inside of the hole 32, the fulcrum shaft 33
When the nut 36 is incorporated into the nut 36, the compression spring 37 presses the nut 36 once to the upper limit of the fulcrum shaft 33, and then the nut 36 is moved downward to the initial set state. Difficult work is required.

Therefore, according to the present invention, in the belt tension adjusting structure proposed above, the axial length of the pulley arm can be made compact, the thrust of the pressing means for generating the damper effect can be increased, and the apparatus can be easily assembled. The purpose is to propose a device.

[0009]

In order to solve the above-mentioned problems, the present invention provides a boss provided on a pulley arm with a hole into which a fixed fulcrum shaft is fitted, and the facing surface of the hole and the fulcrum shaft. A guide that is relatively inclined in the axial direction of the fulcrum shaft is formed, and an engaging member that engages with the guide and moves in the axial direction is incorporated between the hole and the fulcrum shaft. The coupling member is axially pressed by the pressing means arranged outside the boss.

[0010]

As described above, by providing the pressing means on the outside of the boss of the pulley arm, the engaging member inside the hole and the pressing means can be arranged in parallel, and the height of the pulley arm can be shortened.

Further, since the outer diameter of the pressing means is not regulated, the thrust can be freely set, and further, the engaging member can be set in a state where the pressing means is contracted, so that the assembling work of the apparatus can be easily carried out. It

[0012]

1 and 2 show a belt tension adjusting device of an embodiment. As shown in the figure, the pulley arm 1
A boss 3 whose inside is the hole 2 is formed at one end,
A tension pulley 4 pressed against the belt A is rotatably attached to the other end by a bearing 5.

A fulcrum shaft 6 standing on a fixing member such as an engine block is fitted in the hole 2. The fulcrum shaft 6 is composed of a collar 7 having a flange 7a at its lower end and a tightening bolt 8 inserted through the inside of the collar 7. Bearings 9, 9 that receive a radial load when rotating
Is incorporated.

On the inner peripheral surface of the hole 2 of the pulley arm 1, a plurality of parallel spline guides 1 are arranged parallel to the axis.
0 is formed, and a plurality of helical spline guides 11 that are twisted at a constant angle with respect to the axis are formed on the outer peripheral surface of the collar 7 of the fulcrum shaft 6 that faces it.
Further, between the pulley arm 1 and the fulcrum shaft 6, nuts 12 whose outer peripheral surface and inner peripheral surface engage with the parallel spline guide 10 and the helical spline guide 11, respectively, are attached.

On the other hand, a coil-shaped compression spring 13 is fitted on the outside of the boss 3 of the pulley arm 1, and the upper end of this compression spring 13 and the lower end of the nut 12 inside the hole 2 are connected by a spring seat 14. ing. This spring seat 14
Through holes 15, 15 provided on the peripheral surface of the boss 3 are inserted, and the through holes 15, 15 can freely move up and down within the range of the vertical dimension.

The inclination of the helical spline guide 11 is as shown in FIG. 2 when the pulley arm 1 receives the tension from the belt A.
When it is rotated counterclockwise, the nut 12 is pushed into the bottom of the hole 2 to reduce the compression spring 13. The twist angle α of the helical spline guide 11 with respect to the parallel spline guide 10 is set to be smaller than the friction angle between the sliding surfaces of the spline guides 10 and 11 and the nut 12.

In the belt tension adjusting device of the embodiment having the above structure, the fulcrum shaft 6 is fixed to the engine block or the like by the tightening bolt 8 and the tension pulley 4 is pressed against the belt A to be mounted. At the time of initial setting, the compression spring 13 is previously contracted to a state as shown in FIG. 1 by using a jig such as a clip, and in that state,
The nut 12 is engaged with the fulcrum shaft 6 and the spline guides 10 and 11 of the hole 2 and set on the spring seat 14.

From this initial set state, when the compression spring 13 is released from the contracted state and the pulley is pressed against the belt, the spring force of the compression spring 13 which is deformed and the reaction from the belt A are restored. When the forces are balanced, the nut 12 stops moving, and a constant tension is applied to the belt.

When the tension of the belt increases from the above-mentioned balanced state and the pulley arm 1 rotates counterclockwise, the nut 1
2 is pushed, but the helical spline guide 11 and the parallel spline guide 10 form a wedge angle with respect to the nut 12, and the frictional resistance of the sliding surface between the nut 12 and both spline guides 10 and 11 remarkably increases. The movement of 12 is locked, and the rotation of the pulley arm 1 is stopped.

On the contrary, when the tension of the belt decreases from the above-mentioned balanced state and the pulley arm 1 rotates clockwise, the spring force of the compression spring 13 assists the movement of the nut 12, and the helical spline guide 11 and the parallel spline guide 10 move. Does not form a wedge angle with the nut 12,
2 moves smoothly. Therefore, the pulley arm 1
Swivels rapidly toward the slack belt to maintain constant belt tension.

In the above structure, the nut 12 and the compression spring 1
Since 3 is arranged in parallel inside and outside the boss 3 of the pulley arm 1, the heights of the fulcrum shaft 6 and the pulley arm 1 can be shortened by the amount of overlap in parallel as compared with the structure shown in FIG.

Further, since the diameter dimension of the compression spring 13 is not restricted by the inner diameter of the hole 2, the spring diameter and the outer diameter dimension can be arbitrarily set, and the thrust on the nut 12 can be set in a wide range. it can.

3 and 4 show another embodiment.
In this example, the parallel track grooves 2 are provided as guides for the engaging members on the hole 2 of the pulley arm 1 and the peripheral surface of the fulcrum shaft 6, respectively.
0 and a helical track groove 21 are formed, and a rolling element 23 guided by a cage 22 is incorporated as an engaging member in both track grooves 20, 21. Further, the retainer 22 and the compression spring 13 arranged outside the boss 3 of the pulley arm 1 are connected by the spring seat 14 to apply a pressing force in the axial direction to the rolling element 23. Other structures and operations are the same as those of the above-described embodiment, and the same parts are designated by the same reference numerals and the description thereof will be omitted.

As described above, by using the rolling element 23 as the engaging member instead of the nut 12, the rolling element 23 moves while rolling partially with respect to the track grooves 20 and 21 when the damper acts. Therefore, it is possible to obtain smooth rotation characteristics of the pulley arm.

In the above embodiment, the fulcrum shaft 6 is provided with the helical spline guide and the helical track groove. However, the pulley arm 1 is provided with the helical spline and the helical track groove, and the fulcrum shaft 6 is provided with the parallel spline guide and the parallel track. You may make it form a groove. Further, a helical spline or a helical track groove may be formed on both the pulley arm 1 and the fulcrum shaft 6, and the twist angles of the splines and the track groove may be different.

Although the compression spring 13 is shown as the pressing means for the nut 12 and the rolling element 23, a disc spring, a rubber material or the like may be used instead.

[0027]

As described above, according to the present invention, since the engaging member and the pressing means can be arranged in parallel inside and outside the pulley arm, the height of the pulley arm and the fulcrum shaft can be shortened, and the rigidity of the device can be improved. You can

Further, by providing the pressing means on the outside of the pulley arm, there is an advantage that the dimensional change of the pressing means and the setting of the thrust force can be freely set, and the engaging member and the pressing means can be easily set.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an embodiment.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a vertical sectional front view of another embodiment.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 pulley arm 2 hole part 3 boss 4 tension pulley 6 fulcrum shaft 10 parallel spline guide 11 helical spline guide 12 nut 13 compression spring 14 spring seat 15 through hole 20 parallel track groove 21 helical track groove 22 retainer 23 rolling element

Claims (1)

[Claims] 1. A boss provided on a pulley arm is provided with a hole into which a fixed fulcrum shaft is fitted, and guides which are respectively inclined relative to the axial direction of the fulcrum shaft are provided on opposing surfaces of the hole and the fulcrum shaft. An engaging member that is engaged with each of the guides and moves in the axial direction is incorporated between the hole and the fulcrum shaft, and the engaging member is axially moved by the pressing means arranged outside the boss. Belt tension adjustment device designed to be pressed.