JP2005163867A - Auto-tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auto-tensioner that is usable for a long period by using a support member of resin provided with low aggressiveness to aluminum members, and high abrasion resistance for itself. <P>SOLUTION: This auto-tensioner is provided with a bracket 2 having an oscillation arm part 2a for supporting a tension pulley 7, a support 1 engaged with a boss part 2b in the bracket 2 to support the bracket 2 to be capable of oscillating, a torsion coil spring 3 disposed around the boss part 2b to contract in accordance with oscillating action of the bracket 2, and the support member 10 disposed between the torsion coil spring 3 and the boss part 2b. The support member 10 is formed of resin material comprising olefin polymer dispersed in polyamide resin base material. In this constitution, service life of the auto-tensioner can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an auto tensioner for appropriately maintaining belt tension in a belt driving mechanism.

  For example, an auto tensioner is used in a belt transmission mechanism that transmits engine power to auxiliary machines such as a compressor for an air conditioner of an automobile and an alternator to keep the tension acting on the belt moderate.

  In general, this auto tensioner is provided with a vibration damping mechanism such as a friction plate in order to attenuate the tension pulley swinging while allowing the tension pulley to move in response to a change in belt tension caused by engine rotation fluctuations. A mechanism (damper mechanism) is provided (see Patent Document 1).

  The auto tensioner further includes a torsion coil spring that urges the tension pulley toward one of the swing ends and a swing member (rotating member) that supports the tension pulley in order to further enhance the damping effect of the swing of the pulley. A resin support member (spring support) is disposed between the boss portion of the member (see Patent Documents 2 to 4).

  FIG. 1 is an axial front view for explaining swinging of a tension pulley in an auto tensioner, and FIG. 2 is a cross-sectional view taken along line XX in FIG.

  This auto tensioner includes a tension pulley 7 around which a belt V is wound, an aluminum die-cast bracket (swing member) 2 having a swing arm portion 2a that rotatably supports the tension pulley 7, and the bracket. An aluminum support member (fixing member) 1 having a support shaft portion 1a for swingably supporting 2 and a support shaft portion 1a of the support member 1 and a boss portion 2b of the bracket 2 are disposed. A resin bush 4 and a torsion coil spring 3 interposed between the bracket 2 and the support member 1 are configured as main components.

  The torsion coil spring 3 is disposed in a non-contact state between the boss portion 2b of the bracket 2 and the outer cylinder portion 1b of the support member 1, and both end portions 3a and 3b are support members that serve as spring seats. 1 is locked in a locking hole 1k provided in the vicinity of the bottom 1c and a locking hole 2k provided in the vicinity of the flange 2c of the bracket 2, and accommodated in a torsionally compressed state. This torsion coil spring 3 urges the swing arm portion 2a and the tension pulley 7 in a certain direction (the direction of arrow A in FIG. 1) by its torsional restoring force.

  An annular pressing plate 6 is fixed to the tip of the support shaft portion 1a of the support member 1 of the auto tensioner, and a friction plate is interposed between the pressing plate 6 and the flange portion 2c of the bracket 2. 5 is interposed. Accordingly, when the friction plate 5 is pressed against the flange portion 2c and the presser plate 6 by the extension restoring force of the torsion coil spring 3, the swing of the swing arm portion 2a is caused by the sliding generated between them. Damped by dynamic friction resistance (damper effect).

  A resin support member (support portion) 10 having a shape along the outer peripheral surface of the boss portion of the bracket 2 is disposed in the vicinity of the proximal end portion of the support shaft portion 1a. With this configuration, in the above-described auto tensioner, the inner periphery of the torsion coil spring 3 in the region where the moment load from the belt V acts is in contact with the outer peripheral surface of the support member 10, so that the swing arm portion 2 a is supported by the support shaft 10. Inclination with respect to the axis line (swing axis) of the portion 1a is suppressed, and uneven wear of the bush 4 can be prevented.

  FIG. 3 is a perspective view showing an appearance of a conventional support member used in this type of auto tensioner. These support members 10 are generally formed using aliphatic polyamide resin or the like, which is a general-purpose engineering plastic, and a cylindrical portion 11 that fits to the outer periphery of the boss portion 2b of the bracket 2, and the cylindrical portion 11 It consists of an annular flange portion 12 projecting radially from one end portion.

  In order to prevent the support member 10 from rotating together with the boss portion 2b of the bracket 2, various support structures (rotation preventing means) for the circumferential direction have been proposed for these support members 10. For example, FIG. 4 to FIG. 6 are examples of the shape of the support member in which portions (engagement holes 12a, protrusions 12b, and protrusions 12c) that engage with predetermined positions of the support member 1 are formed.

JP 2000-320628 A Japanese Unexamined Patent Publication No. 7-113448 JP-A-7-151198 JP-A-8-42648

  By the way, in the auto tensioner as described above, the support member made of a relatively soft resin is worn by sliding contact with the torsion coil spring due to the reduced diameter of the torsion coil spring due to the swing of the tension pulley. There was a problem.

  In addition, in order to suppress wear of the support member, attempts have been made to add various reinforcing agents such as glass fiber to the resin forming the support member, but the bracket (swing member) and the support with which it comes into sliding contact are also made. Since the member (fixing member) is formed of an aluminum material in consideration of water resistance, weight reduction, and the like, the strengthened support member sometimes wears the aluminum member.

  The present invention has been made in view of such circumstances, and can be used over a long period of time by using a resin support member that combines low aggression against an aluminum member and its own high wear resistance. The purpose is to provide an auto tensioner that can be used.

  In order to achieve the above-mentioned object, the invention according to claim 1 is fitted with a bracket having a swing arm portion that rotatably supports a tension pulley around which a belt is wound, and a boss portion of the bracket. A support member having a support shaft portion for swingably supporting the bracket, a torsion coil spring disposed around the boss portion and reducing the diameter in accordance with the swing operation of the bracket, and the torsion coil spring, In an auto tensioner provided with a support member disposed between the boss portion, the support member is formed using a resin material in which an olefin polymer is dispersed in a polyamide resin base material. To do.

  The present invention, as a material constituting the resin support member of the auto tensioner, by blending a polymer that improves sliding against aluminum into a base material of engineering plastic that is excellent in mechanical strength such as wear resistance and heat resistance, It is intended to achieve the intended purpose.

  That is, according to the invention described in claim 1, by using a resin in which an olefin polymer having high compatibility with the base material is dispersed in a polyamide resin base material having excellent mechanical properties, an aluminum member is obtained. It is possible to provide a support member that has both low aggression resistance against and high wear resistance. In other words, it is possible to achieve both of these characteristics by blending a relatively hard polymer having a high wear resistance with a relatively soft polymer that functions as a lubricating component that enhances surface slip.

  Here, as the polyamide resin base material used for the support member, an aromatic polyamide resin is preferably employed. (Claim 2)

  The aromatic polyamide resin is a polyamide having an aromatic ring in the main chain and is synthesized from an aromatic diamine and an acid chloride of a dicarboxylic acid by interfacial polycondensation or low-temperature solution polycondensation. This aromatic polyamide resin is known as a raw material for fibers having a higher melting point, higher strength and higher elastic modulus than aliphatic polyamide resin, and has preferable characteristics as a material for a support member that requires wear resistance. . Specific examples of the aromatic polyamide resin include PA6T or PA9T. In addition, the use of an aromatic polyamide resin has an advantage that not only strength, elastic modulus and heat resistance but also weather resistance and chemical resistance are improved.

  Further, as the olefin polymer to be blended in the polyamide resin base material, a modified polyolefin selected from the group consisting of ethylene-propylene-diene rubber, ethylene-propylene rubber, polypropylene and polyethylene (Claim 3), carboxylic acid or its acid Modified polyolefin grafted with anhydride (Claim 4), or modified polyolefin modified by copolymerization with any one of α, β-unsaturated carboxylic acid and its ester and metal salt (Claim 4) ) Is preferred.

Among the olefin polymers, the modified polyolefin is particularly excellent in compatibility with the polyamide resin, and has a characteristic that it can be easily dispersed and mixed with the polyamide resin base material. In addition, it is preferable that the ratio which occupies for all the components of these modified polyolefin exists in the range of 5-35 weight%. If the ratio of the modified polyolefin in all the components is less than 5% by weight, the effect of adding the modified polyolefin is not sufficiently exhibited, and the sliding property of the support member may not be sufficiently improved. Further, in the case where the proportion of the modified polyolefin exceeds significantly 35% by weight, the proportion of relatively polyamide resin matrix is reduced, problems in such physical characteristics and mechanical strength of the support member is caused There is a fear.

  With this configuration, the auto tensioner improves the wear resistance of the resin support member itself, and also suppresses wear of an aluminum member (such as a bracket) that is in sliding contact with the support member. Therefore, the auto tensioner of the present invention can be a long-life auto tensioner free from troubles caused by these wears.

The best mode for carrying out the invention will be described below.
The basic configuration of the auto tensioner in the present embodiment is the same as that of the conventional auto tensioner, and the tension pulley 7 around which the belt V is wound, and the swing arm portion 2a that rotatably supports the tension pulley 7. An aluminum bracket (oscillating member) 2 having an aluminum support member, an aluminum support member (fixing member) 1 having a support shaft portion 1a for swingably supporting the bracket 2, and a support shaft portion 1a of these support members 1. A resin bush 4 interposed between the boss 2b of the bracket 2 and a torsion coil spring 3 interposed between the bracket 2 and the support member 1 are configured as main components (FIG. 1 and FIG. 2).

  In addition, the biasing mechanism of the tension pulley 7 by the torsion coil spring 3, the swing damping mechanism (damper mechanism) of the tension pulley 7 by the friction plate 5 and the like, and the tilt suppression mechanism with respect to the swing shaft of the tension pulley 7 by the support member 10 Etc. are the same as those of the conventional example, and detailed description thereof is omitted.

  A feature of the auto tensioner in the present embodiment is that the support member 10 disposed in the vicinity of the base end portion of the support shaft portion 1a uses a resin material in which a modified polyolefin (polymer) is dispersed in an aromatic polyamide resin base material. It is a point that is formed. In addition to the above-described components, various additives such as an inorganic filler as a colorant and a copper-based or organic-based stabilizer may be added.

With the above configuration, the support member 10 has high wear resistance and has low aggression against the aluminum member due to slippage of the surface.
Therefore, the auto tensioner of the present embodiment improves the wear resistance of the resin support member 10 itself, and also suppresses the wear of the aluminum member (bracket 2 or the like) slidably in contact with the support member 10, and thus has a long life. Can be a long auto tensioner.

Although the shape of the support member 10 is not particularly limited, it is preferable that the support member 10 be disposed in the vicinity of the proximal end portion of the support shaft portion 1a of the support member 1.

  Further, the support member 10 may be formed integrally with the bush 4. With this configuration, the support member 10 can be easily arranged at a predetermined position, and by integrating it, the rotation of the bush 4 can be prevented at the same time, so that it can have a function as a damper that attenuates swinging, Is preferred.

It is explanatory drawing which shows rocking | fluctuation of the tension pulley in an auto tensioner. FIG. 2 is a cross-sectional view taken along line XX in FIG. 1 showing the structure of the auto tensioner. It is an external appearance perspective view which shows the structure of the resin-made support members 10 used for the auto tensioner. 6 is an external perspective view showing another structural example of the resin support member 10. FIG. 6 is an external perspective view showing another structural example of the resin support member 10. FIG. 6 is an external perspective view showing another structural example of the resin support member 10. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support member 1a Support shaft part 1b Outer cylinder part 1c Bottom part 2 Bracket 2a Oscillating arm part 2b Boss part 2c Claw part 3 Torsion coil spring 4 Bush 5 Friction plate 6 Presser plate 7 Tension pulley 10 Support member 11 Cylindrical part 12 Flange part

Claims (4)

A bracket having a swing arm portion that rotatably supports a tension pulley around which the belt is wound, and a support member having a support shaft portion that is fitted to a boss portion of the bracket so as to swingably support the bracket. An auto-tensioner comprising a torsion coil spring disposed around the boss portion and having a diameter reduced in accordance with the swinging motion of the bracket, and a support member disposed between the torsion coil spring and the boss portion In
The auto tensioner, wherein the support member is formed using a resin material in which an olefin polymer is dispersed in a polyamide resin base material.   The autotensioner according to claim 1, wherein the polyamide resin base material is an aromatic polyamide.   The auto-tensioner according to claim 2, wherein the olefin polymer is a modified polyolefin selected from the group consisting of ethylene-propylene-diene rubber, ethylene-propylene rubber, polypropylene, and polyethylene. The olefin polymer is modified by copolymerization with one of a modified polyolefin grafted with a carboxylic acid or an acid anhydride thereof, or an α, β-unsaturated carboxylic acid or ester thereof and a metal salt. The autotensioner according to claim 2, which is a modified polyolefin.

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