JP2005127380A - Autotensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightened and cost-reduced autotensioner with an improved sliding characteristic on a contact face between a stationary member or a movable member and a friction material. <P>SOLUTION: This autotensioner for appropriately holding tension of a belt comprises a stationary member 2 fixed to a vehicle body and the like, a movable member of an arm-like structure rotatably supported by the stationary member 2, a pulley 7 engaged with a belt installed at an arm-like distal end of a movable member 3, a coil spring 4 energizing the movable member 3 to the stationary member 2 in a predetermined direction, and a friction material 5 interposed between the movable member 3 and the stationary member 2, and attenuating and converging oscillation of the movable member 3. The friction material 5 is thermoplastic resin, and a sliding part 6 of the stationary member 2 sliding with the friction material 5 is formed of an alumite layer of aluminum or aluminum alloy. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an auto tensioner for automatically maintaining a belt tension appropriately.

  An auto tensioner is used as a device for maintaining an appropriate tension of a belt for driving an auxiliary machine of an automobile engine. In general, this auto tensioner automatically controls the belt tension using the force of the spring, but as a method of damping and converging the swing of the auto tensioner, there are a hydraulic damper method and a friction damper method. Broadly divided. Of these, the latter friction method generally comprises a movable member to which a pulley is attached and a fixed member fixed to the vehicle body, and both of them move relative to each other via a shaft portion so as to make the belt tension as constant as possible by a torsion spring.

  In this case, a friction material having a predetermined friction coefficient is arranged on the shaft portion between the movable member and the fixed member, and by applying an appropriate surface pressure, the frictional energy generated during sliding causes the movable member to move. The swing is attenuated and converged in a short time, and the belt tension is kept as constant as possible.

  Generally, an aluminum alloy casting manufactured by a die casting method is used for the movable member and the fixed member. However, automobile parts are required to be light and low in price, but the aluminum alloy is not always satisfied with light weight and low price.

  For this reason, it is known that a fixing case (fixing member) of an autotensioner applies a synthetic resin, particularly an aromatic nylon resin blended with graphite. It is also known to apply an aromatic nylon resin in which graphite is blended in a swing arm (movable member) of an autotensioner or a swing arm and a tension pulley. (For example, see Patent Document 2)

  However, in general, the thermoplastic resin friction material is manufactured by an injection molding method, and the aluminum alloy casting is manufactured by a die casting method. Therefore, in particular, the surface roughness of the aluminum alloy casting is generally about 10 to 12 μm in 10-point average roughness. In sliding between resin and metal, the amount of wear on the resin side, which is low in hardness compared to the amount of metal wear, is overwhelmingly large, and the larger the surface roughness of the metal, the greater the amount of wear. It is known that the speed is great.

  In an auto tensioner, the most important point in terms of performance and quality is the sliding characteristics of the friction part of this metal (aluminum alloy casting) and resin. (1) The sliding is smooth, stick-slip does not occur, and no noise is generated. (2) The wear rate is low and a predetermined life is satisfied. (3) A stable damping torque is obtained, and the change with time of the friction coefficient of the sliding portion is small. It is essential to satisfy such performance and sliding characteristics.

However, with current auto tensioners, noise may occur due to stick-slip depending on the characteristics of the engine of the automobile or the running conditions, misalignment may occur in the drive belt due to high wear speed, or damping torque may be generated during use. It had a problem of abnormally decreasing.
JP 2002-106653 A JP 2002-106654 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an auto tensioner that achieves weight reduction and cost reduction and has improved sliding characteristics on a contact surface between a fixed member or a movable member and a friction material.

  In the first aspect of the present invention, the fixing member fixed to the vehicle body, the movable member of the arm-like structure that is rotatably supported by the fixing member, and the belt provided at the arm-like tip of the movable member. An engaging pulley, a coil spring that biases the movable member in a predetermined direction with respect to the fixed member, and a friction material that is interposed between the movable member and the fixed member and attenuates and converges the swing of the movable member. This is an auto tensioner to keep the tension of the belt provided moderately, using thermoplastic resin as the friction material, and the sliding part of the fixed member that slides with the friction material is formed of aluminum or aluminum alloy alumite layer It is a thing. For this reason, in the friction between the thermoplastic resin of the friction material and the alumite layer of aluminum or an alloy thereof, sliding is smooth and stick-slip does not occur, noise is hardly generated, wear rate is reduced, and The change with time of the friction coefficient is small, and a stable damping torque can be obtained.

  In the invention according to claim 2 of the present application, the alumite layer is further filled with or adhering a lubricant to the fine pores formed in the surface layer, so that the slidability is further improved and the thermoplastic which is a friction material. The wear rate of the resin is reduced. And improving the sliding characteristics of the counterpart material (aluminum or its alloy casting) that rubs against the friction material not only reduces the wear rate of the friction material, but also reduces stick noise and reduces noise. There is.

  In the invention of claim 3, at least one selected from polytetrafluoroethylene, ultrahigh molecular weight polyethylene, silicone oil, molybdenum disulfide, low molecular weight perfluorocarbon, and polyethylene wax is used as the lubricant.

  In the invention according to claim 4, at least one thermoplastic resin selected from nylon 66, nylon 46, polyacetal, polyethylene terephthalate, polyphenylene sulfide, and syndiotactic polystyrene is used as the friction material.

  In the autotensioner of the present invention, when aluminum or an alloy thereof is anodized, the alumite layer has a good surface roughness, so the wear rate of the friction material, which is the friction counterpart material, is higher than that of the cast (die cast) material. Has the effect of reducing the size. In addition, fine pores exist in the anodized layer, and by further impregnating the fine pores with a lubricant, better sliding characteristics can be obtained, and the wear rate of the friction material as the friction counterpart material is increased. In addition to being reduced, stick slip is less likely to occur, and noise is reduced.

FIG. 1 is a schematic explanatory view of an example of an auto tensioner according to the present invention. The auto tensioner 1 fixes a fixed member 2 fixed to a fixed body (not shown) such as an automobile, a movable member 3 of an arm-like structure that is rotatably supported by the fixed member 2, and the movable member 3. A coil spring 4 that urges the member 2 in a predetermined direction, and a friction material 5 that is interposed between the movable member 3 and the fixed member 2 to attenuate and converge the swing of the movable member 3 are provided. The friction material 5 is fixed to the movable member 3, and the interface with the fixed member 2 is a sliding portion 6. The movable member 3 is fixed to a shaft portion 8 supported by a pulley 7 engaged with the belt via a bearing 9.
The auto tensioner is not limited to the structure shown in FIG.

  The friction material 5 can be produced by molding with an injection molding machine, for example. The friction material 5 has a cylindrical shape with both ends opened, and an oil groove (not shown) is formed on the inner peripheral surface. Moreover, this friction material 5 is formed in the cross-sectional taper shape which becomes a small diameter slightly from one end part to the other end part.

  The friction material 5 is made of nylon 66, nylon 46, polyacetal, polyethylene terephthalate, polyphenylene sulfide, syndiotactic polystyrene, or the like.

  The fixed member 2 and the movable member 3 are made of aluminum or aluminum alloy casting (die casting), and the sliding portion 6 of the fixed member 3 that slides on the friction material 5 is formed of an alumite layer. When the anodized aluminum or its alloy is anodized (alumite treated), the anodized layer has an excellent surface roughness, and therefore has the effect of reducing the wear rate of the friction material 5 as a friction counterpart.

  The alumite layer 10 is a porous layer, and is formed of hexagonal columnar cells 14 which are present on the surface of an aluminum or aluminum alloy layer 11 and have a fine hole 13 at the center, as shown in FIG. Then, the alumite layer 10 is immersed in a lubricant contained in a container, and then placed in a decompression tank and decompressed at a predetermined pressure to impregnate the lubricant into the fine pores 23 to further improve the sliding characteristics. it can.

  As the lubricant, polytetrafluoroethylene, ultrahigh molecular weight polyethylene, silicon oil, molybdenum disulfide, low molecular weight perfluorocarbon, polyethylene wax, or the like can be used alone or in combination.

In the following, the present invention will be described in more detail with reference to specific examples.
Example 1
The plate of the die-cast aluminum alloy casting (material: JIS ADC12) shown in FIG. 3 is immersed in a 15% by volume sulfuric acid bath without subjecting the surface to machining or polishing, and a current of 3A is passed. Anodizing was performed to form an alumite layer having a thickness of about 40 μm. On the other hand, nylon 66 and polyacetal were injection molded in the shape shown in FIG. 3 as friction materials for wear rate measurement, and the wear rate test was performed with a thrust wear tester in combination with the anodized aluminum alloy casting described above. .

  In the measurement of the wear rate in the thrust wear test, the surface pressure of the sliding part is 2.0 MPa, the sliding speed is 100 mm / sec (the center position of the width of the friction material), the sliding time is 24 hours, and the test ambient temperature is room temperature. This was carried out without using a lubricant, and a contact-type shape measuring device was used as a method for measuring the amount of wear.

  After carrying out the wear test continuously for 24 hours, the wear amount of nylon 66 and polyacetal for wear rate measurement was measured to obtain the average wear rate. The result is shown in FIG. The combination of the friction material and the friction counterpart material in FIG. 4 is made of a friction material made of nylon 66 (PA66) or polyacetal (POM) at the front and an aluminum alloy casting or anodizing treatment with no surface treatment at the rear. Indicates a casting. It can be seen that both nylon 66 and polyacetal are effective in prolonging the life of the auto tensioner by reducing the wear rate by anodizing the aluminum alloy die-cast product as the friction counterpart.

Example 2
In the same manner as in Example 1, a die-cast aluminum alloy casting (material: JIS ADC12) shown in FIG. 3 was put into a 15% by volume sulfuric acid bath without subjecting the surface to machining or polishing. Anodization was carried out by flowing a current of 3 A, and an alumite layer having a thickness of about 40 μm was formed.

  The anodized layer formed by anodizing the aluminum alloy is composed of hexagonal columnar cells having a fine hole in the center as shown in FIG. The anodized aluminum alloy casting is immersed in an emulsion of polytetrafluoroethylene resin (PTFE), and the container filled with the PTFE emulsion is placed in a vacuum tank and decompressed to about 0.0001 MPa. Holding for 3 minutes, the fine pores were impregnated with PTFE.

  Furthermore, the aluminum alloy casting impregnated with PTFE was heated at 350 to 360 ° C. for 10 minutes to melt the PTFE, thereby promoting the impregnation of the PTFE into the fine pores in the anodized layer. On the other hand, nylon 66 and polyacetal were injection molded in the shape shown in FIG. 3 as friction materials for wear rate measurement, and a wear rate test was performed with a thrust wear tester in combination with the anodized aluminum alloy casting described above. . The measurement conditions of the wear rate in the thrust wear test are exactly the same as in Example 1.

  After the wear test was conducted continuously for 24 hours, the wear amount of the friction material for wear rate measurement was measured, and the average wear rate was obtained. The result is shown in FIG. The combination of the friction material and the friction mating material in FIG. 5 is a friction material made of nylon 66 (PA66) or polyacetal (POM), an aluminum alloy casting without surface treatment at the rear, and an aluminum alloy casting in which PTFE is impregnated with an alumite layer Indicates. Nylon 66, which is a friction material, and polyacetal are both effective in extending the life of an auto tensioner by reducing the wear rate of an aluminum alloy die-cast product, which is a friction material, by anodizing and impregnating with PTFE. .

Example 3
In the same manner as in Example 2, a die-cast aluminum alloy casting (material: JIS ADC12) shown in FIG. 3 was put into a 15% by volume sulfuric acid bath without subjecting the surface to machining or polishing. Anodization was carried out by flowing a current of 3 A, and an alumite layer having a thickness of about 40 μm was formed. The anodized aluminum alloy casting is immersed in silicon oil, and the container filled with silicon oil is placed in a vacuum tank and decompressed to about 0.0001 MPa. It was impregnated with silicone oil.

  On the other hand, nylon 66 and polyacetal were injection molded in the shape shown in FIG. 3, and a wear rate test was conducted with a thrust wear tester in combination with the aluminum alloy casting impregnated with PTFE after the above-described anodizing treatment. The measurement conditions of the wear rate in the thrust wear test are exactly the same as in Example 1.

  After carrying out the wear test continuously for 24 hours, the wear amount of nylon 66 and polyacetal was measured, and the average wear rate was determined. The result is shown in FIG. The combination of the friction material and the friction counterpart material in FIG. 6 indicates a friction material at the front portion, an aluminum alloy without surface treatment at the rear portion, or an aluminum alloy in which an alumite layer is impregnated with silicon oil. Nylon 66 and polyacetal are both effective in extending the life of the auto tensioner by reducing the wear rate by subjecting the aluminum alloy die-cast product, which is a friction counterpart, to anodization and impregnation with silicon oil.

Example 4
In the same manner as in Example 2, a die-cast aluminum alloy casting (material: JIS ADC12) shown in FIG. 3 was put into a 15% by volume sulfuric acid bath without subjecting the surface to machining or polishing. Anodization was carried out by flowing a current of 3 A, and an alumite layer having a thickness of about 40 μm was formed. The anodized aluminum alloy casting is used as a cathode, ammonium thiomolybdate is contained at 400 g / liter, the others are made of ammonium chloride and additives, and the cathode current density is in an aqueous solution having a pH of 3 to 3.5. Was subjected to secondary electrolysis at 2.5 to 3, thereby depositing molybdenum disulfide (MoS ₂ ) in fine pores in the alumite layer.

  On the other hand, nylon 66 and polyacetal were injection molded in the shape of FIG. 3 and combined with an aluminum alloy casting in which molybdenum disulfide was precipitated after the above-described anodizing treatment, and a wear rate test was conducted with a thrust wear tester. The measurement conditions of the wear rate in the thrust wear test are exactly the same as in Example 1.

After carrying out the wear test continuously for 24 hours, the wear amount of nylon 66 and polyacetal was measured, and the average wear rate was determined. The result is shown in FIG. In the combination of the friction material and the friction counterpart material in FIG. 7, the friction material made of nylon 66 (PA66) or polyacetal (POM) is deposited on the front portion, and MoS ₂ is deposited on the aluminum alloy casting or alumite layer without surface treatment on the rear portion. An aluminum alloy casting is shown. Nylon 66 and polyacetal are both effective in extending the life of the auto tensioner by reducing the wear rate by using an aluminum alloy casting in which MoS ₂ is impregnated in the alumite layer, which is the friction counterpart.

Example 5
The fixing member 2 of the auto tensioner shown in FIG. 1 was manufactured by the surface treatment method of Examples 1 to 4, and an endurance test of the auto tensioner was performed. Polyacetal was used as the friction material 5, and the friction material 5 was fixed to the movable member 3 to make the interface between the friction material 5 and the fixed member 2 a sliding portion.

  The surface treatment of the fixing member 2 is preferably performed only on the sliding portion of the fixing member 2 and the friction material 5, but in the case of the present embodiment, the same conditions as in the previous embodiment are applied to the entire surface of the fixing member 2. I went there. This fixed member 2 was assembled into an auto tensioner, and a simulated movable test was performed under the following conditions.

[Test conditions]
1. Movable test temperature: 100 ± 5 ° C
2. 2. Mobile test time: 200 hours Surface pressure of sliding part: about 1.5 MPa
4). Pulley center displacement: ± 3 mm
5). Oscillation frequency: 20Hz
6). Sliding part lubrication: Silicone grease application (during assembly)

The amount of wear of the friction material (polyacetal) by the simulated movable test is as shown in FIG. 8. In this case, the friction counterpart material is an aluminum alloy casting without surface treatment, aluminum with only an alumite layer formed by anodization. An alloy casting, an aluminum alloy casting in which an anodized layer is impregnated with PTFE, an aluminum alloy casting in which an anodized layer is impregnated with silicon oil, or an aluminum alloy casting in which MoS ₂ is deposited on the anodized layer are shown. This is remarkably reduced by performing the above-described anodizing treatment on the fixing member 2 of the aluminum alloy casting. As a result, it was confirmed that the auto tensioner of this example exhibited good friction resistance even in a simulated operation test close to the conditions used for an actual automobile.

  The auto tensioner according to the present invention can be widely used as a device that automatically keeps the tension of an auxiliary machine driving belt mounted on a multi-axis drive device such as an automobile engine automatically and appropriately.

It is a schematic explanatory drawing of an example of the auto tensioner which concerns on this invention. It is a schematic diagram of an alumite layer. It is a schematic perspective view which shows the test piece shape for the abrasion rate measurement of the friction material which concerns on a present Example, and a counterpart material. 2 is a graph showing average wear rates of nylon 66 (PA66) and polyacetal (POM) in a thrust wear test in Example 1. FIG. It is a graph which shows the average abrasion rate of the same resin in the thrust abrasion test in Example 2. 6 is a graph showing the average wear rate of the same resin in the thrust wear test in Example 3. It is a graph which shows the average abrasion rate of the same resin in the thrust abrasion test in Example 4. 6 is a graph showing the amount of wear of a fixing member after an endurance test with an auto tensioner in Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Auto tensioner 2 Fixed member 3 Movable member 4 Coil spring 5 Friction material 6 Sliding part 7 Pulley 8 Shaft part 9 Bearing 10 Anodized layer 13 Fine hole

Claims (4)

  A fixed member fixed to a vehicle body, a movable member of an arm-like structure that is rotatably supported by the fixed member, a pulley that is provided at an arm-like tip of the movable member and engages with a belt, and a movable member A belt provided with a coil spring that urges the fixed member in a predetermined direction and a friction material that is interposed between the movable member and the fixed member and attenuates and converges the swing of the movable member to maintain a moderate tension. An autotensioner comprising: a thermoplastic resin as a friction material; and a sliding portion of a fixing member that slides on the friction material is formed of an alumite layer of aluminum or an aluminum alloy.   The autotensioner according to claim 1, wherein the alumite layer is filled or attached with a lubricant in fine pores formed in the surface layer.   The autotensioner according to claim 2, wherein the lubricant is at least one selected from polytetrafluoroethylene, ultrahigh molecular weight polyethylene, silicone oil, molybdenum disulfide, low molecular weight perfluorocarbon, and polyethylene wax. The autotensioner according to any one of claims 1 to 3, wherein the friction material is at least one thermoplastic resin selected from nylon 66, nylon 46, polyacetal, polyethylene terephthalate, polyphenylene sulfide, and syndiotactic polystyrene.

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