JPH0552420U - Belt tension adjustment device - Google Patents

Abstract

(57) [Summary] [Object] The present invention aims to stabilize the frictional force in a device for imparting a buffering force to the rotation of the pulley arm by the frictional force between the damper bolt and the pulley arm, and makes lubricating oil unnecessary. [Structure] A damper bolt 10 made of synthetic resin containing a lubricant is attached to a fulcrum shaft 8 of a fixing member 6 via a spline 9, and the damper bolt 10 is screwed onto a thread 12 of a pulley arm 1. A coil spring 14 for pressing the bolt 10 is incorporated in the pulley arm 1, and a tension adjusting spring 18 is connected to the pulley arm 1 and the fixing member 6. The self-lubricating property of the synthetic resin stabilizes the frictional force between the damper bolt 10 and the thread 12.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a belt tension adjusting device used for a belt for driving an accessory of an engine.

[0002]

[Prior Art]

 The belt tension adjusting device used for the accessory drive belt of an automobile engine has a damper mechanism built in the pulley arm to prevent the vibration of the pulley arm from resonating due to the slight vibration applied from the belt. Is taken.

FIG. 2 shows a conventional belt tension adjusting device proposed by Japanese Utility Model Laid-Open No. 63-28949. In this device, a hole 24 provided in a pulley arm 23 is rotatably fitted to a fulcrum shaft 22 provided upright on a fixing member 21, and a guide step 25 composed of a key and a key groove is provided on the fulcrum shaft 22. The damper bolt 26 is attached so as to be movable in the axial direction, and the damper bolt 26 and the thread 27 of the hole 24 are screwed together. An elastic member 28 for pressing the damper bolt 26 downward is incorporated in the hole 24, and both ends of the tension adjusting spring 29 arranged outside the pulley arm 23 are connected to the pulley arm 23 and the fixing member 21, respectively. ..

In the above-described structure, the belt tension is applied to the pulley 30 mounted on the pulley arm 23 by the spring force of the tension adjusting spring 29, and the friction force generated on the screw surface of the bolt 26 by the spring force of the elastic member 28 causes the pulley arm to move. A damper effect is provided to buffer the rotation of 23.

[0005]

[Problems to be solved by the device]

 In the above belt tension adjusting device, the fixing member 21 and the damper bolt 26 fixed to the engine block and the like are usually made of iron, and the rotating pulley arm 23 is made of a light alloy such as aluminum alloy. The frictional force becomes unstable at the sliding portion of the damper bolt 26 and the pulley arm 23 where the light alloy comes into contact, and it is necessary to fill it with lubricating oil such as oil or grease. However, when the inside of the pulley arm 23 is filled with the lubricating oil in this way, a sealing structure for enclosing the lubricating oil is required, which causes a problem of complicating the structure of the device.

Further, since the coefficient of linear thermal expansion differs greatly between iron and an aluminum alloy, a slight change occurs in the sliding portion between the damper bolt 26 and the pulley arm 23 due to heat change, and the screw surface of the damper bolt 26 has even friction. It may not be applied.

Therefore, an object of the present invention is to provide a belt tension adjusting device that does not use lubricating oil and can maintain a stable frictional force between a damper bolt and a pulley arm and a stable screwed state.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, this invention is one in which a damper bolt is formed of a synthetic resin that can be injection-molded, and the synthetic resin contains a lubricant.

[0009]

[Action]

 Since the synthetic resin itself has an excellent self-lubricating property, the frictional force between the sliding portion of the damper bolt and the pulley arm is stable and the lubricating oil can be dispensed with. In particular, when a synthetic resin contains a lubricant such as graphite or Teflon, the friction resistance of the sliding portion can be further reduced, and the wear resistance can be improved.

Further, when the synthetic resin contains a fiber reinforcing material such as glass fiber, the linear expansion coefficient can be changed. Therefore, the synthetic resin and the light alloy forming the pulley arm have the same linear expansion coefficient. By doing so, thermal deformation between the damper bolt and the pulley arm can be controlled to be constant.

The above synthetic resin is preferably a material having self-lubricating property, high heat resistance, easy injection moldability and easy to manufacture damper bolts. For example, polyether ether ketone (PEEK), Resins such as polyphenylene sulfide (PPS), polyamide imide, injection-moldable thermosetting polyimide, and thermoplastic polyimide can be used.

[0012]

【Example】

 FIG. 1 shows a belt tension adjusting device according to an embodiment. The pulley arm 1 is made of an aluminum alloy, a tension pulley 3 is rotatably attached to one end of the pulley arm 1 through a bearing 2, and a hole 4 is formed on the inner end of the pulley arm 1 at the other end. A guide wall 5 is provided.

The fixing member 6 fixed to the engine block and the like is composed of a base 7 and a fulcrum shaft 8 standing upright in the center thereof, and the fulcrum shaft 8 is fitted into the hole 4 of the pulley arm 1. is doing. The fixing member 6 is integrally formed of an iron material such as cast iron or an aluminum alloy.

The base of the fulcrum shaft 8 is a spline 9 composed of a polyhedron, and a damper bolt 10 is fitted into the spline 9. The inner diameter surface of the damper bolt 10 is formed of a polyhedron corresponding to the spline 9, and the damper bolt 10 is moved by the guide of the spline 9 in the axial direction of the fulcrum shaft 8, but the rotation is stopped.

On the outer peripheral surface of the damper bolt 10, multiple threads 11 having a large helix angle are formed, and the threads 11 are screwed into the threads 12 of the hole 4 of the pulley arm 1.

The damper bolt 10 contains one of the synthetic resins such as PEEK and PPS described above, a lubricant of graphite or Teflon, and is molded by injection molding. In addition, the content of fiber reinforcement such as glass fiber is adjusted so that the linear expansion coefficient is similar to that of aluminum alloy, and the difference in deformation between the damper bolt 10 and the ridge 12 of the hole 4 due to temperature change. Is small.

A collar member 13 is press-fitted into the upper end of the fulcrum shaft 8, and a coil spring 14 is incorporated between the collar member 13 and the damper bolt 10. The coil spring 14 is assembled in a compressed state, and its spring force applies a pressing force to the damper bolt 10 in the axial direction (downward direction in FIG. 1).

On the other hand, the upper and lower ends of the fulcrum shaft 8, that is, between the collar member and the peripheral surface of the hole 4 and between the base end 8a of the fulcrum shaft 8 and the peripheral surface of the hole 4, respectively. Bearing members 15 and 16 forming a radial bearing are incorporated. A bearing member 17 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.

For each of the bearing members 15, 16 and 17 described above, a sliding bearing material having a small surface friction resistance is used. For example, like the damper bolt 10, polyether ether ketone (PEEK) or polyimide (PI) is used. A synthetic resin with excellent heat resistance and wear resistance is used.

A tension adjusting spring 18 composed of a coil spring is arranged outside the guide wall 5, and one end of the spring 18 is engaged with the pulley arm 1 and the other end is engaged with the base 7 of the fixing member 6. ..

In the figure, reference numeral 19 denotes a cover for covering the opening of the hole 4 of the pulley arm 1 to prevent dust and the like from entering the radial bearing portion.

In the belt tension adjusting device of the embodiment having the above structure, when the fixing member 6 is fixed to the engine block or the like and the tension pulley 3 is pressed against the belt to rotate the pulley arm 1 at a fixed angle, The tension adjusting spring 18 is compressed and twisted, and a constant tension is applied to the belt by the spring force of the tension adjusting spring 18 which tries to restore.

When the tension of the belt increases from the above-mentioned balanced state and the pulley arm 1 rotates, the damper bolt 10 moves upward, and the coil spring 14 is compressed and contracted. For this reason, the pressing force of the coil spring 14 increases, and a large frictional resistance is generated between the damper bolt 10 and the screw surface of the hole 4, and a large resistance force acts on the rotation of the pulley arm 1.

Conversely, when the belt tension decreases from the above-mentioned balanced state and the pulley arm 1 rotates in the opposite direction to the above, the damper bolt 10 moves downward and the coil spring 14 is stretched. Therefore, the pressing force applied from the coil spring 14 to the damper bolt 10 acts in a direction that assists the rotation of the pulley arm 1, and the pulley arm 1 can rotate with a small resistance.

In the above-described operation, the sliding damper bolt 10 and the threads 11 and 12 of the hole 4 always generate a stable frictional force due to the surface lubrication of the synthetic resin, and a uniform pressing force is applied to the entire circumference. .. Further, since the frictional force on the surface of each screw thread 11 and 12 is not biased, the progress of wear of the screw surface is suppressed and stable damper characteristics are obtained.

Further, since the coefficient of linear expansion of the damper bolt 10 and the pulley arm 1 are set to be equal to each other, the displacement of the deformation does not occur between the damper bolt 10 and the pulley arm 1 due to the heat change, and the stable screw between the damper bolt 10 and the screw thread 12 is provided. It is possible to maintain a good condition.

As the elastic member for pressing the damper bolt 10, a spring material such as a wave washer or a disc spring, or rubber may be used instead of the exemplified compression coil spring.

Further, the spline 9 may be constituted by a number of spline grooves extending in the axial direction or a combination of a key groove and a key instead of the illustrated polyhedron, and the damper bolt 10 can be moved only in the axial direction. Any other structure can be adopted as long as it has a function of giving and stopping the movement in the rotation direction.

[0029]

【effect】

 As described above, according to this invention, since the damper bolt is made of the self-lubricating synthetic resin containing the lubricant, it is possible to stabilize the frictional force of the sliding portion with the thread of the pulley arm, which is excellent. It is possible to obtain excellent damper characteristics.

Further, since the lubricating oil can be dispensed with, the seal structure for sealing it can be omitted, and the structure of the device can be simplified.

Further, by making the linear expansion coefficient of the synthetic resin the same as that of the pulley arm, it is possible to reduce the deviation of deformation with the pulley arm due to thermal change, and to maintain a uniform threaded state.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional front view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulley arm 2 Tension pulley 6 Fixing member 8 Support shaft 9 Spline 10 Damper bolts 11 and 12 Threads 14 Coil spring 18 Tension adjustment spring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 125: 28) C10N 40:06

Claims (1)

[Scope of utility model registration request] 1. A fulcrum shaft erected on a fixed member is rotatably fitted in a hole provided in a pulley arm, and a damper bolt is attached to the fulcrum shaft via a guide means that allows movement only in the axial direction. At the same time, the damper bolt is screwed into the thread formed in the hole, an elastic member is provided in the hole to press the damper bolt in the axial direction, and belt tension is applied to the pulley attached to the pulley arm. A belt tension adjusting device in which a tension adjusting spring is connected, wherein the damper bolt is formed of an injection-moldable synthetic resin, and the synthetic resin contains a lubricant.