JP2003287097A - Autotensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autotensioner equipped with a friction member which has a one-piece body in fabrication and in which grooves remain until it wears out. <P>SOLUTION: When both sides of a friction plate 10 for applying pivot friction to a pivot arm are represented as A and B sides and a thickness is represented as t, the A side is formed with radially penetrating grooves 10c of a depth t/2 at four equal intervals in a circumferential direction, and the B side is similarly formed with the grooves 10c but at positions offset by 45 degrees from the grooves 10c of the A side. <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.
With such an auto tensioner, mounting error of auxiliary equipment,
It is possible to absorb dimensional changes due to temperature changes, variations 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 101 is made of a ring-shaped clutch facing material, and its thickness is about 3 mm. Friction plate 1
In the radial direction of 01, four grooves 101b are provided, and abrasion powder generated from the sliding surface 101a due to abrasion is
Along with the swing of the swing arm, these are collected in these grooves 101b and naturally discharged from the groove end portions.

[0004]

In the conventional automatic tensioner as described above, when the sliding surface 101a is worn, the groove 101b becomes shallower and finally the groove 101b.
Disappears. When the groove 101b disappears, abrasion powder is less likely to be discharged and covers the sliding surface 101a, so that the frictional force decreases. Therefore, replacement is required at that time. However, originally, the friction plate 101 can be used until it is completely worn away, and it is uneconomical that it cannot be used until the end, and it is inconvenient because the replacement time is early. If the groove 101b has the same depth as the plate thickness, the groove 101b exists until the end, but in this case, since the groove 101b passes through in the radial direction, the friction plate 101 is divided into four pieces. In this case, since the four friction plates are manufactured separately, it is difficult in manufacturing to accurately match the thickness with each other. If the thicknesses do not match, the desired friction area cannot be obtained.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide an autotensioner which is a single piece in terms of manufacturing and which has a friction member in which a groove exists until it wears out.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a swing arm which rotatably supports a pulley around which a belt is wound at its tip end, a support member which swingably supports the swing arm, and the support. A spring for urging the swing arm in a predetermined swing direction with respect to a member is interposed between a swing portion of the swing arm and an immovable portion on the support member side to swing the swing arm. An automatic tensioner comprising a friction member having a thickness t for imparting rocking resistance against movement, wherein a plurality of bottomed grooves are provided on the front surface and the back surface of the friction member, which are the sliding surface and the back surface, respectively. At least one groove end of each groove is formed at a shifted position and penetrates the friction member (claim 1). In the friction member of the auto tensioner configured as described above, the grooves on the front and back sides are not connected to each other because the positions of the grooves are deviated on the front and back sides. Therefore, the friction member is a single piece in terms of manufacturing and is not divided by the groove. In addition, there are grooves until they wear out, and wear particles are scraped up in the grooves. The abrasion powder collected is discharged to the outside from the groove end portion penetrating the friction member.

In the above automatic tensioner (claim 1), the depth d1 (<t) of the groove on the front surface side and the depth d2 (<t) of the groove on the back surface side are at least d1 + between the pair of front and back grooves.
It may have a relationship of d2 ≧ t (claim 2). In this case, since the depth of the groove has a relationship of d1 + d2 ≧ t, the groove always exists until it is worn.

Further, the auto tensioner (claim 1).
In the above, the friction member may be a ring-shaped friction plate, and the grooves may pass through in the radial direction and are equally arranged in the circumferential direction on both the front and back sides (claim 3). In this case, there are many groove ends, and the inside and outside of the friction plate communicate with each other by the groove.

[0009]

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.
It is orthogonal to, and is interposed between the collar portion 4b of the swing arm 4 and the annular pressing plate 11. The friction plate 10 is made of, for example, a clutch facing material having a thickness of about 3 mm. Further, the inner peripheral shape of the pressing plate 11 and the outer peripheral shape of the support member 7 on the right end side (FIG. 1) form a chrysanthemum-shaped detent structure that fits with each other (see FIG. 2). Then, the pressing plate 11 is fitted to the support member 7, and the support member 7
It is fixed by a retaining means (not shown) attached to the screw hole 7d.

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. Sharp small projections (not shown) are provided on the surface of the flange portion 4b in contact with the friction plate 10 in at least four equal intervals in the circumferential direction. The friction plate 10 is fixed to 4b.
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 swing arm 4 swings,
The B surface of the friction plate 10 slides on the pressing plate 11.

3A is a front view of the friction plate 10, FIG. 3B is a sectional view taken along line BB in FIG. 3A, and FIG.
FIG. 6B is a sectional view taken along line CC in FIG. V-shaped grooves 10c passing through in the radial direction are formed on the A surface (the front side of (a)) of the friction plate 10 in the circumferential direction at equal intervals, and the other surface is the flange portion 4b. Of the fixed surface 10a. Further, on the surface B, the same grooves 10c are formed in the same manner as the grooves 10c on the surface A, which are offset from each other by 45 degrees in the circumferential direction, and the other surfaces are sliding surfaces 10b. Each groove 10c on A side
Depth d1 is d1 = t / 2 with respect to the plate thickness t. Similarly, the depth d2 of each groove 10c on the B surface is also d2 with respect to the plate thickness t.
= T / 2. Since the positions of the grooves 10c are deviated between the A surface and the B surface, the grooves 10c on both surfaces are not connected to each other and the friction plate 10 is not divided, and the friction plate 10 is a single unit in manufacturing. ing.

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 as a “non-moving part” with respect to the “oscillating part” is fixed. Therefore, the pressing plate 1
Due to the relative rotation between 1 and the collar portion 4b, friction is generated between the friction plate 10 and the pressing plate 11 fixed to the collar portion 4b. As a result, swing resistance (friction resistance) is imparted to the swing arm 4.

FIG. 4 is a perspective view showing the process of wear of the friction plate 10, with the B side facing up. The initial friction plate 10 is in the state shown in (a), and the depth of the groove 10c on the B surface is the above-mentioned d2, but the sliding surface 10b is gradually worn by continuous use, and ) State. That is, the depth of the groove 10c on the B surface becomes shallow. When the wear further progresses, as shown in (c), the groove 10c on the B surface disappears, and the bottom of the groove 10c on the A surface appears instead. Where A
Although the bottom of the surface groove 10c is illustrated as being linear,
This is a “groove” that forms a gap because the bottom of the V-groove actually has a certain width.

At the time of (c), the friction plate 10 is divided into four parts. As described above, since the small projections of the collar portion 4b bite into the friction plate 10, the friction plate 10 is divided even if divided. 10
Does not move. When the wear further progresses, as shown in (d), the gap of the groove 10c expands. Then, the friction plate 10 eventually wears out. Thus, the friction plate 10 always has the groove 10c until it is worn away, and the abrasion powder is collected in the groove 10c and discharged from the groove end passing through the friction plate 10. Therefore, the frictional force does not decrease, and the frictional plate 10 can be used with a stable frictional force until it wears out. Since the grooves 10c passing through in the radial direction are evenly arranged in the circumferential direction, there are many groove ends and the inside and outside of the friction plate 10 communicate with each other by the grooves 10c. Irrespective of the posture, the abrasion powder can be smoothly discharged from each groove 10c to the outside.

The groove 10c in the above embodiment is V
Although it is a groove, various shapes such as a U shape and a rectangular shape can be adopted. However, it is preferable that the groove width becomes narrower as it becomes deeper, as in the case of the V groove, because it is easy to remove from the mold during molding. Further, in the above-described embodiment, the number of the grooves 10c is four on both the front and back sides, but the number can be increased or decreased as necessary.

In the above embodiment, d1 = d2 = t / 2 is set for each of the front and back grooves, but the depth of one of the front and back grooves exceeds t / 2 and the depth of the other groove is less than t / 2. Or both sides may have a depth exceeding t / 2. That is, it is preferable that d1 + d2 ≧ t. However,
Since it is difficult to release the mold when the groove is deep, the relationship of d1 = d2 = t / 2 is preferable in consideration of this point. Further, in the above embodiment, the depth of the groove 10c is constant on each surface, but this does not necessarily have to be the same. For example, the front and back sides may have two depths. However, even in this case, in order to ensure that the grooves always exist regardless of the degree of wear, at least d1 + is formed between the pair of front and back grooves.
It is necessary to satisfy the relationship of d2 ≧ t.

However, the relationship of d1 + d2 ≧ t is not always an essential condition. For example, even in the case of d1 + d2 <t, if the value of t- (d1 + d2) is sufficiently small, even if there is a time when the groove disappears in the middle of wear, it is a short period and the influence of the abrasion powder at that time increases. Since the groove on the back side appears in front, there is almost no problem in practical use, and the friction plate 10 can be used with a substantially stable friction force until it is worn out. Further, in the above-described embodiment, the groove 10c is assumed to pass through in the radial direction, but this does not necessarily have to pass through, and the direction of the groove is not limited to the radial direction. In short, if at least one of the groove ends penetrates the friction plate 10, the abrasion powder can be discharged.

The structure of the friction plate 10 having the grooves 10c on the front and back sides as described above is not limited to the one provided at the place of the above-described embodiment or the ring-shaped one, but the swing arm 4 and the support member 7 are provided. It can be applied to various forms of friction members provided between and. For example, in the case of an auto tensioner having a structure in which the bush 8 has a friction function, the same action and effect can be obtained by providing similar grooves on the outer surface and the inner surface of the bush along the direction of the swing central axis X. be able to.

[0022]

The present invention constructed as described above has the following effects. According to the auto tensioner of claim 1,
Although the friction member is a single piece in terms of manufacturing, since the groove exists until it wears out, the abrasion powder is collected in the groove and discharged from the groove end portion to the outside. Therefore, in the auto tensioner, the frictional force does not decrease and the frictional member can be used with a stable frictional force until it is worn out.

According to the automatic tensioner of the second aspect, the groove is always present until the friction member is worn out, so that the friction member can always be used with a stable friction force.

According to the autotensioner of the third aspect, since there are many groove ends and the inside and outside of the friction plate communicate with each other through the grooves, wear from each groove to the outside regardless of the mounting position of the friction plate. The powder can be discharged smoothly.

[Brief description of drawings]

FIG. 1 is a partial cross-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 friction plate of the auto tensioner, FIG. 3B is a sectional view taken along line BB in FIG. 3A, and FIG. 3C is a sectional view taken along line CC in FIG. is there.

FIG. 4 is a perspective view showing a process of wear of the friction plate.

FIG. 5 is a perspective view showing a friction plate in a conventional auto tensioner.

[Explanation of symbols]

1 belt Two pulleys 4 swing arm 4b Collar part (oscillating part) 4c tubular part 7 Support member 9 torsion coil spring 10 Friction plate (friction member) 10c groove 11 Presser plate (immovable part)

Claims (3)

[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. Is interposed between the swinging portion of the swinging arm and the immovable portion on the support member side to provide a swinging resistance against the swinging of the swinging arm. An automatic tensioner comprising a friction member having a thickness t to be applied, wherein a plurality of bottomed grooves are formed at positions offset from each other on a front surface and a back surface which are sliding surfaces of the friction member,
An auto tensioner, wherein at least one groove end of each groove penetrates through the friction member. 2. The depth d1 (<t) of the groove on the front surface side and the depth d2 (<t) of the groove on the back surface side have a relationship of d1 + d2 ≧ t at least between the pair of front and back grooves. Auto tensioner. 3. The friction member is a ring-shaped friction plate,
The autotensioner according to claim 1, wherein the grooves are formed in both the front and back sides in the radial direction and are evenly arranged in the circumferential direction.