JP2007192361A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic tensioner capable of preventing the resonance of a torsion coil spring, and absorbing and relieving micro-vibration of a rocking member caused by this resonance. <P>SOLUTION: This automatic tensioner is formed by arranging a vibration control material 7 composed of a hard resin between the torsion coil spring 4 energizing a tension pulley and a boss part 2b of the rocking member (a bracket 2). An elastic body 8 is interposed and arranged between an inner peripheral surface of this vibration control material 7 and an outer peripheral surface of the bracket boss part 2b. This constitution restrains the resonance in the axial direction of this torsion coil spring 4 by slidingly contacting an inner diameter surface of the spring 4 with an outer peripheral surface of the vibration control material 7, and absorbs and relieves vibration transmitted to the bracket 2 via the vibration control material 7 by the elastic body 8. Thus, this automatic tensioner can prevent the occurrence of an abnormal sound caused by rocking of the pulley. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 swing of the tension pulley while permitting the movement of the tension pulley in accordance with a change in the belt tension caused by the engine fluctuation. A mechanism (damper mechanism) is provided (see, for example, Patent Documents 1 and 2).

  3 is an axial sectional view showing the structure of a conventional auto tensioner, and FIG. 4 is a right side view of the auto tensioner. FIG. 5 is a partial sectional view for explaining the internal structure of the case of the auto tensioner.

  The auto tensioner includes a tension pulley P around which a belt B is wound, a bearing 10 that supports the rotation of the tension pulley P, a swing arm portion 2a including the bearing 10 and a swing base portion (a cylindrical boss portion). 2b and an annular flange portion 2c), a bracket (swing member) 2, a fixed case (support member) 1 having a support shaft portion 1a for swingably supporting the bracket 2, and a support shaft of these cases 1 A bush 3 interposed between the portion 1a and the boss portion 2b of the bracket 2, and a coil spring 4 interposed between the bracket 2 and the case 1 to urge the pulley P in a certain direction. It is configured as a main part.

  A friction plate guide (presser plate 6) having a petal-shaped hole (inner peripheral edge 6x) at the center is fixed to the tip of the support shaft portion 1a of the case 1. Further, a friction plate 5 made of a clutch facing material, a brake lining material, or the like is disposed on an end surface of the flange portion 2c of the bracket 2 facing the pressing plate 6, and the friction plate 5 is connected to the torsion coil spring. By being pressed against the presser plate 6 by the extension restoring force of 4, the swing of the swing arm portion 2a is attenuated by the sliding frictional resistance generated between them (damping effect).

  By the way, when the auto tensioner is vibrated at a frequency equal to the natural frequency of the torsion coil spring 4, the torsion coil spring 4 resonates in the axial direction and the windings interfere with each other to generate noise. It is known that there may be. Therefore, in a conventional auto tensioner, a cylindrical vibration isolator 7 is disposed between the torsion coil spring 4 and the boss 2b of the bracket 2 as means for suppressing this resonance (Patent Documents 3 to 3). See 4).

JP 2003-83405 A JP 2003-287095 A Japanese National Patent Publication No. 10-502997 Japanese Patent Laid-Open No. 2003-120768

  However, the conventional cylindrical vibration isolator 7 is often formed using a relatively hard resin having excellent wear resistance, such as a polyamide resin, in order to withstand sliding friction with the torsion coil spring 4. In some cases, the resonance of the torsion coil spring 4 is transmitted to the bracket 2 through the vibration isolator 7 and a minute vibration is generated in the swing arm portion 2a. Further, such minute vibrations of the swing arm portion 2 a are also transmitted to the bearing 10 that supports the pulley P, and abnormal noise may be generated from the bearing 10.

  The present invention has been made to address the above-described problems, and provides an auto tensioner that can prevent the torsion coil spring from resonating and can absorb and mitigate minute vibrations of the oscillating member caused by the resonance. The purpose is to do.

  In order to achieve the above object, the invention according to claim 1 is directed to a swing member having a swing arm portion and a boss portion that rotatably supports a tension pulley by a bearing provided at a tip, and the boss portion. A support member having a support shaft portion that fits and swingably supports the swing member, and a torsion coil spring that is disposed around the boss portion and is reduced in diameter as the swing member swings. In an auto tensioner in which a cylindrical vibration-proof material made of hard resin is disposed between the torsion coil spring and the boss portion, an inner peripheral surface of the vibration-proof material and the swing member An elastic body is interposed between the outer peripheral surface of the boss portion.

  The present invention is disposed between the torsion coil spring and the boss portion of the oscillating member in order to prevent axial vibration of the torsion coil spring that is reduced in diameter and enlarged in accordance with the oscillation operation of the tension pulley. The cylindrical anti-vibration material has a two-layer structure of a hard resin excellent in wear resistance and an elastic body excellent in vibration absorption, thereby achieving the intended purpose.

  That is, according to the invention of claim 1, an elastic body is provided between the inner peripheral surface of the cylindrical vibration damping material disposed on the inner peripheral side of the torsion coil spring and the outer peripheral surface of the boss portion of the swing member. By interposing and arranging, the vibration transmitted to the swinging member through this cylindrical vibration isolator can be absorbed and relaxed. Moreover, according to this structure, the elastic body arrange | positioned inside a vibration-proof material does not touch a torsion coil spring directly, and there is no fear that the lifetime may fall by abrasion etc. Therefore, the auto tensioner of the present invention can maintain the same durability as the conventional auto tensioner while absorbing minute vibrations of the swing member caused by resonance of the torsion coil spring.

  In addition, rubber | gum can be employ | adopted suitably as a material of the said elastic body (Claim 2). Rubber is a low elastic modulus material, and can absorb the vibrations efficiently due to its expansion and contraction, so that it is preferable as an elastic material.

  As described above in detail, according to the present invention, the resonance of the torsion coil spring that urges the pulley is suppressed, and the minute vibration of the oscillating member caused by this resonance is also absorbed and relaxed. It is possible to provide a quiet auto tensioner that does not generate abnormal noise due to swinging.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is an axial sectional view showing a structure of an auto tensioner in the present embodiment of the present invention, and FIG. 2 is a sectional view taken along the line XX of FIG. In addition, the same code | symbol is attached | subjected to the structural member which has the same function as a prior art example.

  The basic structure of the auto tensioner is the same as that of the conventional example. A tension pulley around which a belt is wound, a bearing (not shown) for supporting the rotation of the tension pulley, and a swing arm portion provided with the bearing 2a, a cylindrical boss 2b, and a bracket (swing member) 2 having an annular flange 2c formed therebetween, and a fixed case having a support shaft 1a for swingably supporting the bracket 2 (Support member) 1, a bush 3 disposed between the support shaft portion 1 a of the case 1 and the boss portion 2 b of the bracket 2, and a torsion coil spring interposed between the bracket 2 and the case 1 4 etc. are constituted as main parts.

  The torsion coil spring 4 is disposed in a non-contact state between the boss portion 2b of the bracket 2 and the outer cylinder portion 1b of the case 1, and both ends thereof are rear end portions of the case 1 serving as spring seats. Locked in a locking hole (not shown) provided in the vicinity of 1c and a locking hole (not shown) provided in the vicinity of the flange 2c of the bracket 2, and accommodated in a torsionally compressed state. The torsion coil spring 4 urges the swing arm portion 2a and the pulley in a certain direction by the torsional restoring force.

  A petal-shaped detent step portion 1x having irregularities in the circumferential direction is formed at the tip of the support shaft portion 1a of the case 1, and a similar petal-shaped hole is formed in the center portion of the detent step portion 1x. A disc-shaped friction plate guide (holding plate 6) having (inner peripheral edge 6x) is fitted and caulked near the outer peripheral edge of the rotation stopper step 1x, thereby being fixed to the case 1 so as not to rotate. . A ring-shaped friction plate 5 made of a clutch facing material, a brake lining material, or the like is interposed between the presser plate 6 and the flange portion 2c of the bracket 2. By being pressed against the presser plate 6 by the extension restoring force of the coil spring 4, the swing of the swing arm portion 2a is attenuated by the sliding frictional resistance generated between them.

  The auto tensioner has a substantially cylindrical shape made of glass fiber reinforced polyamide resin between the torsion coil spring 4 and the boss 2b of the bracket 2 as means for suppressing resonance in the axial direction of the torsion coil spring 4. The anti-vibration material 7 is arranged.

  As shown in FIG. 2, the auto tensioner according to the present embodiment is characterized by a cylindrical rubber elastic body 8 between the inner peripheral surface 7 x of the vibration isolator 7 and the outer peripheral surface 2 x of the boss portion 2 b of the bracket 2. Is the point where is placed. The vibration isolator 7 is provided with one axial slit 7a in the circumferential direction, as in the prior art, and at a predetermined position in the circumferential direction (upward in the drawing) Prior to this, a thick portion 7b that contacts the torsion coil spring 4 is formed.

  With the above configuration, the auto tensioner is in sliding contact with the inner diameter surface of the spring 4 and the outer peripheral surface 7y of the vibration isolator 7 due to the reduced diameter of the torsion coil spring 4 due to the swinging motion of the pulley, as in the conventional example. The resonance in the axial direction of the torsion coil spring 4 is suppressed. The elastic body 8 interposed between the inner peripheral surface 7x of the vibration isolator 7 and the outer peripheral surface 2x of the boss portion of the bracket 2 absorbs minute vibration transmitted to the bracket 2 through the vibration isolator 7. Can be relaxed.

  Furthermore, the elastic body 8 disposed inside the vibration isolator 7 does not directly touch the torsion coil spring 4, and there is no fear that its life will be reduced due to wear or the like. Therefore, the auto tensioner in the present embodiment does not generate abnormal noise due to the swing of the pulley, and can maintain its performance over a long period of time.

  In the present embodiment, the elastic body 8 disposed between the inner peripheral surface 7x of the vibration isolator 7 and the outer peripheral surface 2x of the bracket boss portion 2b is configured using rubber. The material constituting the elastic body used is not limited to this example. Moreover, the shape is also arbitrary.

  Further, the present invention can be widely applied not only to the configuration example in the above embodiment, but also to an auto tensioner in which a vibration isolating material made of resin is disposed between the torsion coil spring and the bracket boss portion.

It is an axial direction sectional view showing the structure of the auto tensioner in this embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line XX in FIG. 1. It is an axial sectional view showing the structure of a conventional auto tensioner. It is a right view of the conventional auto tensioner. It is a partial sectional view explaining the internal structure of the conventional auto tensioner.

Explanation of symbols

1 Case (supporting member)
DESCRIPTION OF SYMBOLS 1a Support shaft part 1b Outer cylinder part 1c Rear end part 1x Non-rotating step part 2 Bracket (swinging member)
2a Swing arm part 2b Boss part 2c Eave part 2x (boss part) outer peripheral surface 3 Bush 4 Torsion coil spring 5 Friction plate 6 Presser plate (friction plate guide)
6x Inner peripheral edge 7 Vibration isolator 7a Slit 7b Thick part 7x Inner peripheral surface 7y Outer peripheral surface 8 Elastic body 10 Bearing B Belt P Tension pulley

Claims (2)

A swing member having a swing arm portion and a boss portion that rotatably supports the tension pulley with a bearing provided at the tip, and a support shaft portion that fits the boss portion and supports the swing member so as to swing freely. And a torsion coil spring disposed around the boss portion and having a diameter reduced with the swinging motion of the swing member, and between the torsion coil spring and the boss portion, In an auto tensioner in which a cylindrical vibration-proof material made of hard resin is arranged,
An auto tensioner, wherein an elastic body is disposed between an inner peripheral surface of the vibration isolator and an outer peripheral surface of a boss portion of the swing member. The auto tensioner according to claim 1, wherein the elastic body is rubber.

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