JP2006070936A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auto tensioner capable of further well reducing the wear amount of a friction member. <P>SOLUTION: This auto tensioner attenuates a variation in the tension of a transmission belt 9 comprising a fixed member 3 having a tapered shaft part and a movable member 4 having a sliding part slidable on the outer periphery of a shaft part through the synthetic resin friction member 11. In this case, the shaft part 10 is formed of one type of materials among a stainless steel, an aluminum-tin alloy, and copper-lead alloy. The shaft part is desirably formed of the aluminum-tin alloy or the copper-lead alloy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an auto tensioner in which a shaft portion of a fixing member is made of a material having rust resistance and high slidability.

  2. Description of the Related Art Conventionally, an auto tensioner has been used as a device for maintaining the tension of an accessory driving belt for 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 that is fixed to a vehicle body (for example, an engine), both of which are connected via a shaft portion so as to make the belt tension constant by a biasing member such as a spring. Make relative movements.

  In this case, a friction (sliding) member having a predetermined coefficient of friction is disposed between the movable member and the fixed member, and an appropriate surface pressure is applied, so that the movable member is caused by frictional energy generated during sliding. The belt tension is attenuated and converged in a short time to keep the belt tension as constant as possible.

For example, as an auto tensioner, the following Patent Document 1 is disclosed. The fixed member is made of an aluminum alloy and the movable member is made of a synthetic resin. The aluminum alloy and the synthetic resin and the friction member slide so that the belt tension is kept constant and frictional energy is generated between the two to move. The swing of the member is attenuated in a short time.
JP 2002-106654 A

  However, when the aluminum alloy is used as the fixing member and the synthetic resin is used as the sliding member as in Patent Document 1, the amount of wear of the sliding member can be reduced compared to the case of using conventional steel. However, in order to further increase the product life, further reduction in the amount of wear of the sliding member has been desired.

  The present invention has been made in view of the above points, and its purpose is to select a material for a fixing member having rust resistance and high slidability, and to further reduce the wear amount of the friction member. It is to provide an auto tensioner that can.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
That is, the autotensioner according to the present invention includes a fixed member having a tapered shaft portion and a movable belt having a movable member having a sliding portion that is slidable on the outer periphery of the shaft portion via a synthetic resin friction member. In the auto tensioner for attenuating fluctuations in tension, the shaft portion is made of any one of stainless steel, aluminum-tin alloy, and copper-lead alloy. The shaft portion is preferably made of an aluminum-tin alloy or a copper-lead alloy material.

  According to the present invention, it is possible to provide an auto tensioner that can more effectively reduce the wear amount of the friction member.

  Next, embodiments of the invention will be described. FIG. 1 is a sectional view showing the overall configuration of an auto tensioner according to an embodiment of the present invention, and FIG. 2 is a top view showing a state in which a transmission belt is wound around the auto tensioner.

  An auto tensioner 1 shown in FIG. 1 has a bracket (fixing member) 3 having a fixing portion 3a fixed to an engine block 2 schematically shown by a two-dot chain line by a bolt or the like not shown, and is swingable with respect to the bracket 3. And an arm (movable member) 4 supported by the robot. A pulley 5 is rotatably supported by a bolt 7 via a ball bearing 6 at the tip of the arm 4 as schematically indicated by a chain line. Further, the arm 4 is urged to turn to one side by a spring (biasing spring) 8 to be described later, whereby the outer peripheral surface of the pulley 5 transmits the rotation of the crankshaft of the engine to an auxiliary machine such as an alternator. For this reason, the belt 9 is configured to abut against the belt 9 (rotating body driving belt) and apply appropriate tension to the belt. The shaft portion 10 has a shape in which a cylindrical portion 10a and a tapered cylindrical hollow tube 10b are integrated from the cylindrical portion 10a side to the arm 4 side.

  The bracket 3 further includes a shaft portion fixing portion 3b and a spring housing portion 3c that houses the spring 8 together with a spring housing portion 4a described later. The shaft portion fixing portion 3b and the spring housing portion 3c are integrally formed. It will be. The shaft portion fixing portion 3 b is formed in a short cylindrical shape to which one end of the shaft portion 10 is fixed, and is provided near the center of the bracket 3 from the engine block 2 side to the arm 4 side. The spring accommodating portion 3c is formed in a concave shape in the longitudinal section with an opening on the arm 4 side, and is formed in an annular shape in a transverse section along the shaft portion fixing portion 3b.

  A cylindrical portion 10a of the shaft portion 10 is press-fitted and fixed to the shaft portion fixing portion 3b. As this press-fitting method, for example, a method of fixing in advance by forming a plurality of fine ribs along the press-fitting direction on the outer peripheral surface of the cylindrical portion 10a can be mentioned. Conversely, a plurality of fine ribs along the press-fitting direction may be formed on the inner peripheral surface of the shaft portion fixing portion 3b.

  The arm 4 includes a spring accommodating portion 4a that accommodates the spring 8 together with the spring accommodating portion 3c, and a tapered cylindrical boss portion 4b from the bracket 3 side to the pulley 5 side. The spring accommodating portion 4a is formed in a concave shape with a vertical cross section opened on the bracket 3 side, is formed in a circular shape with a circular cross section, and does not come into contact even if it rotates inside the spring accommodating portion 3a of the bracket 3. (Outer diameter). The boss portion 4b can insert the shaft portion 10, and a tapered cylindrical synthetic resin friction member 11 is interposed between the outer peripheral surface of the shaft portion 10 and the inner peripheral surface of the boss portion 4b. . The friction member 11 made of synthetic resin is formed by injection molding synthetic resin such as nylon 66, nylon 46, polyacetal, polyethylene terephthalate, polyphenylene sulfide, syndiotactic polystyrene, polytetrafluoroethylene, and the like. A key groove (not shown) is provided in the direction, and is fixed by engagement with a key portion provided on the shaft portion 10 or the boss portion 4a that matches the key groove. The arm 4 is rotatably supported with respect to the bracket 3 via the synthetic resin friction member 11.

  The bracket 3 and the arm 4 are formed by die-casting aluminum or aluminum alloy, and nitriding treatment, soft nitriding treatment, galvanizing, aluminum alloy plating, hard chrome plating, or the like is performed on each surface.

  The shaft portion 10 is disposed so that the axis center coincides with the rotation center of the arm 4. The shaft portion 10 is made of any one of stainless steel, aluminum-tin alloy, and copper-lead alloy.

  Stainless steel has excellent slidability and includes austenitic, ferritic and martensitic stainless steels, and is not particularly limited. Specifically, there are JIS symbols such as SUS302, SUS304, SUS306 (austenite), SUS405, SUS430, SUS434 (ferrite), SUS403, SUS416, SUS431 (martensite).

  The aluminum-tin alloy has slidability due to excellent non-seizure properties, and in the present embodiment, the tin content is preferably 5 to 40% by mass. This is because when the amount exceeds 40% by mass, the mechanical properties deteriorate. In addition, tin, nickel, zinc, antimony and the like may be selectively contained for the purpose of increasing strength. In addition, silicon, copper, manganese, magnesium, nickel, vanadium, or the like may be selectively contained for the purpose of increasing strength.

  The copper-lead alloy has slidability due to excellent foreign material burying property, and in the present embodiment, the lead content is preferably 10 to 30% by mass. This is because if it exceeds 30% by mass, the strength decreases. In addition, tin, nickel, zinc, antimony and the like may be selectively contained for the purpose of increasing strength.

  Each of the above materials has excellent rust resistance such that a thin oxide film is formed on the surface and oxidation does not proceed any more.

  Although not shown, the spring 8 has one end of the spring wire fixed to the bracket 3 and the other end fixed to the arm 4. The spring 8 exerts an urging force for urging the arm 4 to one side with respect to the bracket 3, and at the same time, an axial tensile force in a direction in which the bracket 3 and the arm 4 are brought close to each other. And the arm 4, and as a result, between the hollow cylinder 10 b outer peripheral surface of the shaft portion 10 and the synthetic resin friction member 11, and the tapered inner peripheral surface of the boss portion 4 b and the synthetic resin friction. A predetermined surface pressure is generated by appropriately pressing between the members 11. Therefore, when the arm 4 rotates relative to the bracket 3, the frictional resistance generated between the synthetic resin friction member 11 and each tapered surface resists it.

  Next, the operation of the auto tensioner 1 will be described. First, it is assumed that a belt 9 stretched around a drive shaft of a drive mechanism such as an engine (not shown) is wound around the pulley 5. At this time, the arm 4 provided with the pulley 5 is maintained in a swinging state at a predetermined angle corresponding to the twist restoring force of the spring 10 and the tension of the belt 9.

  For example, when the tension of the belt 9 changes after the drive mechanism starts driving, the restoring force in the extension direction by the spring 8 is applied between the bracket 3 and the arm 4, so that the shaft portion 10 is extended. It is uniformly pressed against the inclined surface of the synthetic resin friction member 11 with a force corresponding to the direction restoring force.

  Further, since the pulley 5 around which the belt 9 is wound is provided in an offset state from the position where the synthetic resin friction member 11 is disposed, the inclined surface between the synthetic resin friction member 11 and the shaft portion 10 due to an overhang load. They are pressed together at both ends.

  As a result, when the tension of the belt 9 changes suddenly in the increasing direction, a sudden fluctuation in tension can be sufficiently suppressed. On the other hand, when the tension of the belt 9 changes in the decreasing direction, the arm 4 can be swung with high followability with respect to the tension change of the belt 9.

  With the above configuration, it is possible to provide an auto tensioner that can further effectively reduce the wear amount of the friction member.

  Bracket 3 made of aluminum alloy die cast, arm 4 made of aluminum alloy die cast, arm 4 having a boss portion 4a having a key portion for engaging with a key groove (not shown) provided in synthetic resin friction member 11, and nylon The auto-tensioner 1 having the same configuration as the above-described embodiment of the spring torque 25 N · m and the damping torque 12 N · m was assembled using the synthetic resin friction member 11 made of 46, the spring 8, and the shaft portion 10. In addition, the axial part 10 consists of the material of each Example which has an element component shown in following Table 1, the thing which consists of steel as the comparative example 1, and the aluminum alloy die-cast (JIS: ADC12) as the comparative example 2. Each was created.

  Each of the shaft portions 10 of the materials of the above examples and comparative examples is assembled to the auto tensioner 1 and the durability test of the auto tensioner 1 (addition of swinging to the pulley 5) is performed under the following test conditions, and the synthetic resin friction member 11 The amount of wear was measured.

(Test conditions)
The test atmospheric humidity is 100 ± 3 ° C., the amplitude at the center of the pulley 5 is 6 mm (peak-to-peak), the oscillation frequency of the pulley 5 is 33 Hz, and the test time is 300 hours. The test results are shown in Table 2 below.

  From Table 2, it can be seen that in Examples 1 to 3, the wear amount of the synthetic resin friction member is significantly reduced as compared with Comparative Examples 1 and 2. Therefore, an auto tensioner having a shaft portion having excellent slidability without any special surface treatment can be provided.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples.

It is sectional drawing which showed the whole structure of the auto tensioner which concerns on one Embodiment of this invention. It is a top view which shows the state by which the transmission belt was wound around the auto tensioner.

Explanation of symbols

1 Auto tensioner 2 Engine block 3 Bracket (fixing member)
4 Arm (movable member)
5 Pulley 6 Bearing 7 Bolt 8 Spring (biasing spring)
9 Belt 10 Shaft 11 Synthetic Resin Friction Member

Claims (2)

A fixing member having a tapered shaft portion;
In an auto tensioner for attenuating fluctuations in tension of a transmission belt comprising a movable member having a sliding portion that is slidable through a synthetic resin friction member on the outer periphery of the shaft portion,
An auto tensioner in which the shaft portion is made of any one of stainless steel, an aluminum-tin alloy, and a copper-lead alloy. The auto tensioner according to claim 1, wherein the shaft portion is made of an aluminum-tin alloy material or a copper-lead alloy material.

Images