JPH05106697A - Belt tension adjusting device - Google Patents

Abstract

PURPOSE:To stabilize frictional force in a bearing part for receiving a radial load between a pulley arm and a supporting point shaft, in a belt tension adjusting device with a damper mechanism built in the pulley arm. CONSTITUTION:A hole part 4 of a pulley arm 1 is fitted to a supporting point shaft 8 of a fixed member 6 to provide bearing members 21, 22 of synthetic resin on both end parts of the supporting point axis 8. A damper bolt 10 is set between both these bearing members 21, 22.

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.

[0002]

2. Description of the Related Art In a belt tension adjusting device used for a belt for driving an accessory of an automobile engine, a damper is brought into contact with a pulley arm in order to prevent the pulley arm from resonating due to the slight vibration generated in the belt. The method of suppressing is taken.

Conventionally, a device in which a screw mechanism is used for such a damper to perform a mechanical shock absorbing action has been proposed.
It is proposed by Japanese Utility Model Laid-Open No. 63-28949.

In this proposal, as shown in FIG. 6, a hole 32 of a cylindrical boss 31 provided at one end of a pulley arm 30.
A fulcrum shaft 34 provided upright on the fixing member 33 is fitted to the fulcrum shaft 34, and the fulcrum shaft 34 is fitted with a bolt 36 through a key groove and a key 35.
Is movably mounted in the axial direction, and the screw thread on the outer periphery of the bolt 36 is screwed into the screw thread 37 provided in the hole 32.

Further, an elastic member 39 for pressing the bolt 36 downward is incorporated between the bolt 36 and the upper wall 38 of the pulley arm 30, and the coil spring 4 arranged outside the boss 31.
One end of 0 is engaged with the pulley arm 30, and the other end is engaged with the fixing member 33.

In the above structure, the spring force generated by the twisting of the coil spring 40 presses the tension pulley 41 attached to the pulley arm 30 against the belt to give a constant tension, and the elastic force of the elastic member 39 causes the bolt. The frictional force generated on the threaded surface of 36 provides the pulley arm 30 with a damper effect.

[0007]

In the above proposed apparatus, the radial load when the pulley arm 30 is rotated by directly sliding the inner peripheral surface of the hole 32 of the pulley arm 30 onto both ends of the fulcrum shaft 34, is applied. I am trying to receive it. However, usually, the fixing member 3 fixed to the engine block or the like is used.
The 3 and the bolts 36 are made of iron such as cast iron, and the rotating pulley arm 30 is formed of a light alloy such as an aluminum alloy. However, there is a problem that the frictional force of the sliding contact portion becomes unstable, seizure and the like occur, and the load-carrying capacity of the bearing portion decreases.

On the other hand, when the sliding contact portion is lubricated with a lubricating oil such as oil or grease, the frictional force can be stabilized, but when the lubricating oil is filled inside the pulley arm 30,
A sealing mechanism for sealing it is required, which causes a problem of complicating the structure of the device.

Therefore, an object of the present invention is to provide a belt tension adjusting device which can stably maintain the friction of the bearing portion between the pulley arm and the fulcrum shaft with a simple structure.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a bearing member for receiving a radial load is interposed between the hole of a pulley arm and both ends of a fulcrum shaft. That is, the structure is such that a threaded portion for the bolt is provided.

[0011]

In the above structure, the friction material generated between the pulley arm and the fulcrum shaft can be stabilized by using a sliding material having a small surface friction resistance for the bearing member. As such a sliding material, a synthetic resin having a self-lubricating property can be used.

When a bending moment is applied to the fitting portion between the fulcrum shaft and the hole of the pulley arm, the acting radial load is received at both ends of the fulcrum shaft. Therefore, by incorporating a bearing member at both ends of the fitting portion and providing a screwing portion of the bolt at a position displaced from the bearing member, it is possible to reduce the outer diameter of the device without lowering the load-carrying capacity. You can

[0013]

FIG. 1 shows a belt tension adjusting device of an embodiment. As shown in the figure, the pulley arm 1 has a tension pulley 3 rotatably attached to a belt via a bearing 2 at one end thereof, and has a hole on the inside at the other end serving as a swing fulcrum. A cylindrical guide wall 5 serving as the portion 4 is provided.

The fixing member 6 fixed to the engine block or the like is composed of a base 7 and a fulcrum shaft 8 standing upright in the center thereof, and the fulcrum shaft 8 has a hole 4 in the pulley arm 1.
Is fitted to.

The root portion of the fulcrum shaft 8 is, as shown in FIGS. 2 and 3, a spline 9 composed of a hexagonal polyhedron.
The damper bolt 10 is fitted to the spline 9. The inner diameter surface of the damper bolt 10 is formed of a hexagonal polyhedron corresponding to the spline 9, and the damper bolt 10 can be moved in the axial direction of the fulcrum shaft 8 by the guide of the spline 9, but cannot rotate. It is like this.

Further, on the outer peripheral surface of the damper bolt 10, there are two threads 1 with a helix angle in the range of 10 to 15 degrees.
1 and 11 are formed, and the screw threads 12 formed on the inner peripheral surface of the hole portion 4 of the pulley arm 1 are screwed into the screw threads 11 and 11.

The damper bolt 10 is the PE described above.
It is integrally molded by injection molding with a heat-resistant synthetic resin such as EK or PI.

On the other hand, a collar member 13 is integrally fixed to the peripheral surface of the tip of the fulcrum shaft 8 by press fitting, and an elastic member 14 composed of a coil spring is incorporated between the collar member 13 and the damper bolt 10. There is. This elastic member 14
Is assembled in a compressed state, and its spring force applies a pressing force to the damper bolt 10 in a fixed axial direction (downward direction in FIG. 1).

At the upper end of the fulcrum shaft 8, a tightening bolt 15 screwed into the tip of the fulcrum shaft 8 and a collar member 13 are provided.
A fulcrum spacer 16 crimped between is attached. As shown in FIG. 4, a protrusion 17 is formed on the peripheral surface of the fulcrum spacer 16, and a recess 19 into which the protrusion 17 is loosely fitted is formed in an opening 18 of the hole 4 into which the spacer 16 is fitted. The rotation angle of the pulley arm 1 is limited to a certain amount by the engagement between the recess 19 and the protrusion 17.

The upper and lower ends of the fulcrum shaft 8, that is, between the collar member 13 and the inner peripheral surface of the hole 4, and between the base end 20 of the fulcrum shaft 8 and the inner peripheral surface of the hole 4. Bearing members 21 and 22 which respectively constitute a radial bearing are incorporated between them. On the other hand, a bearing member 23 that constitutes a thrust bearing is incorporated between the lower end of the guide wall 5 of the pulley arm 1 and the upper surface of the base 7. These bearing members 21, 2
A synthetic resin sliding bearing material having a self-lubricating property and a small surface friction resistance is used for Nos. 2 and 23. In particular, it is desirable to improve durability by using a synthetic resin having high wear resistance, like the damper bolt 10, for the bearing member 23 of the thrust bearing that slides under a large load.

A coil spring 24 is arranged outside the guide wall 5 of the pulley arm 1. One end of the coil spring 24 is engaged with the pulley arm 1 and the other end is engaged with the base 7 of the fixing member 6. The surface of the coil spring 24 is subjected to anticorrosion treatment such as dacro treatment.

In FIG. 1, reference numeral 25 denotes a cover press-fitted into the opening 18 of the hole 4 of the guide wall 5 to prevent dust and the like from entering the radial bearing portion.

The belt tension adjusting device of this embodiment has the above-mentioned structure. When the tension pulley 3 is pressed against the belt to rotate the pulley arm 1 by a certain angle, the coil spring 24 is compressed and twisted. A constant tension is applied to the belt by the spring force of the coil spring 24 that tries to restore.

In this balanced state, the damper bolt 10
Is pressed downward by the elastic member 14, and the pressing force is received by the bearing member 23 through the guide wall 5 of the pulley arm 1. In this case, when the pulley arm 1 rotates,
The damper bolt 10 moves up and down by the guide of the spline 9, but the rotation is stopped. Therefore, the bolt 10
Friction occurs on the threaded surface of the screw thread 12 of the hole 4, and friction also occurs on the bearing member 23 that receives the spring force of the elastic member 14.

Now, when the belt tension increases from the above-mentioned balanced state, the pulley arm 1 rotates and the coil spring 2
4 is further compressed, the damper bolt 10 moves upward, and the elastic member 14 is compressed and contracted. At this time, the pulley arm 1 rotates against the pressing force applied to the damper bolt 10 and against the frictional resistance of the screwing surface between the damper bolt 10 and the screw thread 12. Therefore, a large resistance force acts on the rotation of the pulley arm 1, and the pulley arm 1 slowly follows the tension of the belt.

On the contrary, when the tension of the belt decreases from the above-mentioned balanced state, the pulley arm 1 is rotated in the opposite direction to the above by the force to return the twist of the coil spring 24. In this case, the damper bolt 10 moves downward and the elastic member 14 is stretched. The pressing force applied to the damper bolt 10 acts in a direction that assists the rotation of the pulley arm 1,
Only friction on the screwing surface of the damper bolt 10 serves as resistance. Therefore, the pulley arm 1 can rotate with a small resistance, and quickly follows the loosening of the belt.

In the above operation, a stable frictional force is generated between the hole portion 4 of the rotating pulley arm 1 and the bearing members 21 and 22 due to the surface lubrication of the synthetic resin, so that the pulley arm 1 is always rotated smoothly. Can be done.

Further, in the above structure, since the height of the supporting position of the tension pulley 3 is different from that of the bearing members 21 and 22 forming the radial bearing, the bearing members 21 and 22 are caused by the tension of the belt applied to the pulley 3. A bending moment is applied to, but the radial load due to this moment is
Most of it is received at the outer ends of the bearing members 21, 22. Therefore, compared with the structure in which the bearing member is provided over the entire length of the fulcrum shaft 8, the load capacity against the radial load is not reduced.

Further, a damper bolt 10 and a screw thread 12 are provided at the center of the fulcrum shaft 8 and the hole 4, and the bearing members 21, 2 are provided.
Since the interference with 2 is eliminated, the diameter of the guide wall 5 can be reduced, and the outer diameter of the device can be reduced.

FIG. 5 shows another embodiment. In this example,
A compression coil spring having a rectangular cross section is used as the elastic member 14 '. By making the spring cross section rectangular in this way,
It becomes possible to withstand a higher load. Since the other structure is the same as that of the above-described embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted.

The elastic members 14 and 14 'may be made of spring materials such as wave washers and disc springs, or rubber instead of the exemplified compression coil springs.

Further, the spline 9 does not have to be the hexagonal polyhedron shown in the figure, but a large number of spline grooves extending in the axial direction,
The key groove and the key may be combined, and any other structure can be adopted as long as it has a function of giving the damper bolt 10 movement only in the axial direction and stopping the movement in the rotation direction.

Further, instead of the collar member 13, an elastic member may be received by a retaining ring or the like engaged with the peripheral surface of the fulcrum shaft 8. If it can be assembled, the fulcrum shaft 8
It is also possible to bulge the peripheral surface in the radial direction and receive the elastic member directly at the bulged portion.

Further, the screw thread 11 of the damper bolt 10 is
The number of articles may be three or more, and by setting a large number of articles,
It is possible to form a thread around the entire circumference with a shorter bolt length.

[0035]

As described above, according to the present invention, since the bearing member which receives the radial load is provided between the fulcrum shaft and the pulley arm, the frictional force of the bearing portion can be reduced by selecting a material having low surface friction. Can be stabilized,
A smooth rotation of the pulley arm can be obtained.

Further, since the bearing members are arranged at both ends of the fulcrum shaft where the bending moment is concentrated, and the bolts constituting the damper are arranged between the divided bearings, the load-bearing capacity is not deteriorated and the outside of the apparatus is prevented. The diameter can be made compact.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view showing an embodiment.

FIG. 2 is an enlarged sectional view of the main part of the above.

FIG. 3 is a sectional view taken along line III-III in FIG.

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

FIG. 5 is a partially longitudinal front view showing another embodiment.

FIG. 6 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 pulley arm 4 hole part 6 fixing member 8 fulcrum shaft 9 spline 10 damper bolt 11, 12 screw thread 13 collar member 14, 14 'elastic member 21, 22, 23 bearing member 24 coil spring

Claims (1)

[Claims] 1. A fulcrum shaft erected on a fixing member is fitted into a hole provided in a pulley arm, and a bolt mounted movably in the axial direction on the fulcrum shaft is attached to a screw thread provided in the hole. An elastic member that urges the bolt in a fixed axial direction is incorporated into the hole, and one end of the coil spring arranged outside the hole is engaged with the pulley arm and the other end is engaged with the fixing member. In the belt tension adjusting device, a bearing member for receiving a radial load is interposed between the hole of the pulley arm and both ends of the fulcrum shaft, and a screwing portion of a bolt is provided between the bearing members. Tension adjusting device.