JP2003287095A - Autotensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autotensioner wherein damping effect of vibration energy is stably ensured by preventing a stranding phenomenon of a friction plate even when a great deal of wear dust is generated. <P>SOLUTION: The friction plate 10 and a presser plate 11 for sliding contact of the friction plate are disposed around a pivot central axis X of a pivot arm 4. An annular concave groove 11b centered on the pivot central axis X is formed on a sliding contact surface side of the presser plate 11, and a through hole 11c for discharging the wear dust is formed in a bottom of the groove. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto tensioner for applying a predetermined tension to a belt wound around a pulley.

[0002]

2. Description of the Related Art For example, a belt is generally used to transmit power from an engine to auxiliary equipment such as a compressor for an air conditioner mounted on an automobile.
The tension of this belt is kept constant by the auto tensioner. The auto tensioner has a pulley around which the belt is wound at the tip of a swing arm that can swing around a fixed portion, and applies tension to the belt by the force of a torsion coil spring. A swing resistance is imparted to the swing arm by a friction plate provided near the swing base.
The swing resistance of the swing arm is attenuated by this swing resistance. With such an autotensioner, it is possible to absorb a mounting error of an auxiliary machine, a dimensional change due to a temperature change, a variation in belt length, and the like. Further, it is possible to absorb belt tension fluctuations due to engine rotation fluctuations and the like, prevent belt vibrations and abnormal noises, and ensure the original life of the belt.

FIG. 5 is a perspective view of the friction plate. In the figure, the friction plate 10 is made of a ring-shaped clutch facing material, and its thickness is about 3 mm. Friction plate 10
Eight grooves 10b are provided in the radial direction on one side of the surface, and abrasion powder generated from the sliding surface 10a due to wear is scraped into these grooves 10b as the swing arm swings. 6A is a front view of the fixed-side pressing plate 51 with which the friction plate 101 is in sliding contact, and FIG. 6B is a sectional view thereof. The pressing plate 51 is a disc-shaped metal plate provided with a plurality of recesses 51a as shown in the drawing. These recesses 51a are provided for improving the rigidity of the pressing plate 51 and for accumulating the abrasion powder discharged from the friction plate 10 like the groove 10b. The friction plate 10 and the pressing plate 51 have a structure in which they are in pressure contact with each other, as shown in FIG.

[0004]

In the conventional automatic tensioner as described above, when a large amount of abrasion powder is generated in an engine or the like in which the belt tension fluctuation is large,
The depression 51a of the pressing plate 51 may be filled with abrasion powder. In this case, if more wear is generated,
The frictional force between the friction plate 10 and the pressing plate 51 is reduced. If the frictional force decreases, the damping effect of the swing energy decreases.

On the other hand, the friction plate 10 is moved by the swing of the swing arm.
Turns, but in many cases, this turning amount is ±
It is a small amount of about 2 degrees. Therefore, as shown in FIG. 7B, the friction plate 10 is worn while the facing portion 10p of the friction plate 10 facing the recess 51a remains as a gently raised protrusion, and finally the recess 51a is finished.
The convex shape is formed on the friction plate 10 so as to substantially match the shape.
After a large amount of tension fluctuation occurs after the wear has progressed in this way, the facing portion 10p runs in the circumferential direction from the recess 51a, and a gap is formed between the pressing plate 51 and a portion other than the facing portion 10p of the friction plate 10. Will end up. As a result, the frictional force is significantly reduced and the behavior of the swing arm becomes unstable.

In view of the above-mentioned conventional problems, the present invention prevents the friction plate from riding up and ensures a stable oscillation energy damping effect even when a large amount of abrasion powder is generated. The purpose is to provide an auto tensioner that can

[0007]

SUMMARY OF THE INVENTION An autotensioner of the present invention comprises a swing arm that rotatably supports a pulley around which a belt is wound at its tip, and a support member that swingably supports the swing arm. A spring for urging the swing arm in a predetermined swing direction with respect to the support member, and a swing center axis of the swing arm between the swing portion of the swing arm and the support member. And a friction plate for imparting rocking resistance to the rocking of the rocking arm, and a friction plate provided on one of the rocking part of the rocking arm and the support member to slide the friction plate. A friction plate retainer in which only a ring-shaped groove centering on the swing center axis is formed on the sliding contact surface side, and a through hole for discharging wear powder of the friction plate is provided in the groove. And a member (Claim 1).

In the auto tensioner constructed as described above, only the annular concave groove having the swing center axis as the center is formed on the sliding contact surface side of the friction plate pressing member, which causes wear. Even if the portion of the friction plate facing the groove protrudes from the surroundings, it does not ride on the friction plate pressing member. Therefore, the frictional force is always stably exerted. Further, the abrasion powder of the friction plate is collected in the groove of the friction plate pressing member and discharged from the through hole. Therefore, even if there is a large amount of abrasion powder, this can be discharged.

Further, in the above-mentioned auto tensioner, it is preferable that a plurality of through holes are formed at equal intervals in the circumferential direction at the groove bottom (claim 2). In this case, regardless of the mounting position of the auto tensioner, the abrasion powder is discharged from at least one through hole located at a position where it is easily discharged.

[0010]

1 and 2 are a sectional view and a side view of an auto tensioner according to an embodiment of the present invention, respectively. In FIG. 1, a pulley 2 around which a belt 1 is wound has a ball bearing 3 mounted at the center thereof. The inner ring of the ball bearing 3 is externally fitted to the tip 4a of the swing arm 4 and fixed to the tip 4a by a bolt 5 and a nut 6. In this way, the pulley 2 is rotatably supported by the tip 4a of the swing arm 4. Below the swing arm 4, a collar portion 4b and a tubular portion 4c are formed integrally with the tip portion 4a.

On the other hand, a support member 7 for supporting the swing arm 4
Is a molding member having a supporting base 7a having a hollow interior, a spring receiving portion 7b formed around the supporting base 7a, and a mounting portion 7c. The support member 7 is fixed by fixing it to the fixed part such as the chassis of the vehicle body or the engine with the mounting part 7c. The outer peripheral surface of the support base 7a has a taper shape that is slightly tapered to the right in FIG. 1 due to the draft of the mold. A substantially cylindrical bush 8 is attached to the outer peripheral surface of the support base 7a. The bush 8 is a resin (nylon or the like) having a hardness of HRR 90 to 95.

The swing arm 4 is swingable with respect to the support member 7 by the cylindrical portion 4c of which is externally inserted into the bush 8. A torsion coil spring 9 is mounted between the spring receiving portion 7b of the support member 7 and the tubular portion 4c of the swing arm 4. One end 9a of the torsion coil spring 9 is locked to the support member 7, and the other end 9b is locked to the swing arm 4. With the above configuration, the swing arm 4 can swing (rotate) within a predetermined range with respect to the support member 7 via the bush 8. At this time, the swing base is the cylindrical portion 4c.
And the swing center axis X coincides with the center axis of the support base 7a. The torsion coil spring 9 biases the swing arm 4 in the clockwise direction in FIG. 2 in a state where the belt 1 is wound, and gives a constant tension to the belt 1.

On the other hand, the annular friction plate 10 has a swing center axis X.
Is disposed around the axis of the swing arm 4, is orthogonal to the swing center axis X, and is interposed between the collar portion 4b of the swing arm 4 and the pressing plate 11. The friction plate 10 is made of, for example, a clutch facing material having a thickness of about 3 mm, and has a sliding surface 10a and a groove 10b as shown in FIG. Also, the pressing plate 11
The inner peripheral shape and the outer peripheral shape on the right end side (FIG. 1) of the support member 7 form a chrysanthemum-shaped detent structure that fits with each other (see FIG. 2). Then, the pressing plate 11 is fixed by the retaining means (not shown) attached to the screw hole 7 d of the support member 7 in a state of being fitted to the support member 7.

The torsion coil spring 9 urges the swing arm 4 against the support member 7 by the elastic force in the swing center axis X direction, whereby the collar portion 4b and the pressing plate 11 are rubbed with each other. The plate 10 is sandwiched, and the plates 10 are urged so as to press each other in a direction parallel to the swing central axis X. A large number of sharp small protrusions (not shown) are provided in the circumferential direction on the surface of the flange portion 4b that comes into contact with the friction plate 10. The protrusions bite into the friction plate 10 to cause the flange portion 4b to contact the friction plate. Fix 10 When the front surface of the friction plate 10 on the side fixed to the collar portion 4b is the A surface and the back surface thereof is the B surface, the B of the friction plate 10 is moved by the swing of the swing arm 4.
The surface slides with respect to the pressing plate 11. In addition, the groove 10b
(FIG. 5) is provided on the B side.

FIG. 3A is a front view of the pressing plate 11 (the sliding contact side is the front), and FIG. 3B is a side view.
(C) is a rear view and (d) is a sectional view taken along the line D-D in (c). The pressing plate 11 is a disk-shaped processed metal plate, and has an inner peripheral shape of a chrysanthemum and an outer peripheral shape of a circle as described above. An annular groove 11b is formed on the side of the sliding contact surface 11a with the friction plate 10. It is only this groove 11b that exists as a groove on the sliding contact surface 11a side. Through holes 11c are formed in the bottom of the groove 11b at equal intervals in the circumferential direction, so to speak, the bottom of the groove 11b is partially removed. The groove 11b of the pressing plate 11 attached to the support member 7 (FIG. 1) is an annular groove centered on the swing center axis X (FIG. 1).

Next, the operation of the auto tensioner configured as described above will be described with reference to FIGS. 1 and 2. As the tension of the belt 1 fluctuates, the swing arm 4 moves to the position shown in FIG.
When it is swung in the counterclockwise direction or the clockwise direction, the collar portion 4b shown in FIG. 1 as the "swing portion" rotates around the swing center axis X. On the other hand, the pressing plate 11 is fixed to the support member 7. Therefore, due to the relative rotation between the pressing plate 11 and the collar portion 4b, friction is generated between the friction plate 10 fixed to the collar portion 4b and the pressing plate 11. As a result, swing resistance (friction resistance) is imparted to the swing arm 4.

The abrasion powder of the friction plate 10 generated by the friction between the friction plate 10 and the pressing plate 11 is the groove 10b of the friction plate 10.
(Fig. 5) and is discharged from the groove end. The abrasion powder is also collected in the groove 11b of the pressing plate 11 and discharged from the through hole 11c. By the discharge from the through hole 11c, the abrasion powder is not clogged in the groove 11b and does not come out, and the abrasion powder can be exhausted without limit. Therefore,
Even if there is a large amount of abrasion powder that is generated, such as when the belt tension changes greatly, this can be reliably discharged. Also,
The part of the friction plate 10 facing the groove 11b of the pressing plate 11 does not wear, and the surrounding part wears, so that the part gradually projects from the surroundings, but the projecting part is the groove 11b.
Since it is in the annular opening, the friction plate 10 does not ride on the pressing plate 11 due to the rotation. Therefore, the frictional force is always stably exerted. In this way, even when a large amount of wear powder is generated, it can be reliably discharged, and the rocking energy damping effect can be stably ensured. Further, since the through holes 11c are arranged in the circumferential direction in four equal parts, the abrasion powder is discharged from at least one through hole 11c at a position where it is easily discharged regardless of the mounting posture of the auto tensioner. Therefore, the abrasion powder is more reliably discharged.

FIG. 4 is a view showing another embodiment of the pressing plate 11 in the above-mentioned auto tensioner.
The front view of the said press board 11, (b) is a side view, (c) is a rear view, (d) is the DD sectional view taken on the line in (c). 3 is different from FIG. 3 in that, in addition to the through holes 11c at the bottom of the groove, through holes 11d are equally distributed in the circumferential direction on both side walls of the groove 11b, and are alternately arranged with the through holes 11c at the bottom of the groove. It is the point that is formed. In this case, the through hole 11 formed in the side wall
Since the abrasion powder can also be discharged from d, the abrasion powder can be more reliably discharged regardless of the mounting posture of the auto tensioner.

In each embodiment of the pressing plate 11 in the above-mentioned automatic tensioner, four through holes 11c and 11d are provided, but the number can be increased or decreased as necessary. 1
Even if it is effective even if it is an individual, in that case, if the through hole is not facing downward when the auto tensioner is attached to the vehicle body,
It is necessary to consider that the abrasion powder cannot be quickly discharged to the outside of the pressing plate 11.

Further, in the above-mentioned automatic tensioner, the friction plate 10 rotates together with the collar portion 4b of the swing arm 4 so that the friction plate 1
0 has a structure in which it slides with respect to the pressing plate 11, but, conversely, a disc-shaped pressing plate without grooves and the friction plate 10 are fixed to each other, and a "friction plate pressing member" having the same structure as the pressing plate 11 is provided. May be attached to the collar portion 4b and slid with respect to the friction plate 10. The swing arm 4
Since it is generally a die cast product using an aluminum alloy, the collar portion 4b itself is not suitable as a sliding surface. Further, the shape of the groove 11b of the pressing plate 11 is not limited to the U-shape as in the above embodiment, but may be a V-shape or an arc shape.

[0021]

The present invention constructed as described above has the following effects. According to the auto tensioner of claim 1,
Since only the annular concave groove centered on the swing center axis is formed on the sliding contact surface side of the friction plate pressing member, even if the portion of the friction plate facing the groove protrudes from the surroundings due to wear,
Since it does not ride on the friction plate pressing member,
The frictional force is always exerted stably, and the damping effect of the swing energy can be secured stably. Further, since the abrasion powder of the friction plate is collected in the groove of the friction plate pressing member and is discharged from the through hole, it is possible to reliably discharge the abrasion powder even when the generated abrasion powder is large.

According to the automatic tensioner of the second aspect, the abrasion powder is discharged from at least one through hole located at a position where it is easily discharged regardless of the mounting posture of the automatic tensioner, so that the abrasion powder can be more reliably discharged. Is discharged.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an auto tensioner according to an embodiment of the present invention.

FIG. 2 is a side view of the auto tensioner.

3A is a front view of a pressing plate in the auto tensioner of FIG. 1, FIG. 3B is a side view, and FIG.
(D) is the DD sectional view taken on the line in (c).

4A and 4B are views showing another embodiment of the pressing plate in the auto tensioner of FIG. 1, in which FIG. 4A is a front view of the pressing plate, FIG. 4B is a side view, and FIG. d) is
It is the DD sectional view taken on the line in (c).

FIG. 5 is a perspective view of a friction plate of the conventional and automatic tensioner of FIG. 1.

6A and 6B are a front view and a cross-sectional view of a pressing plate in a conventional auto tensioner.

FIG. 7 is a cross-sectional view showing a contact state between a pressing plate and a friction plate in a conventional auto tensioner.

[Explanation of symbols]

1 belt Two pulleys 4 swing arm 4b Collar part (oscillating part) 7 Support member 9 torsion coil spring 10 Friction plate 11 Press plate (friction plate pressing member) 11a Sliding surface 11b groove 11c through hole 11d through hole X swing center axis

Claims (2)

[Claims] 1. A swing arm that rotatably supports a pulley around which a belt is wound at a tip end portion thereof, a support member that swingably supports the swing arm, and the swing arm with respect to the support member. A spring for urging the oscillating arm in a predetermined oscillating direction, and is arranged between the oscillating portion of the oscillating arm and the supporting member, around the oscillating central axis of the oscillating arm, and oscillating the oscillating arm. A friction plate that gives a rocking resistance to one of the rocking portion of the rocking arm and the supporting member, and the friction plate is slidably contacted with the friction plate. A friction plate pressing member is provided, in which only an annular concave groove centered on the dynamic center axis is formed, and a through hole for discharging abrasion powder of the friction plate is provided in the groove. Tensioner. 2. The auto tensioner according to claim 1, wherein a plurality of the through holes are formed in the groove bottom at equal intervals in the circumferential direction.