JP3889648B2 - Auto tensioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an auto tensioner that applies a predetermined tension to a belt wound around a pulley.
[0002]
[Prior art]
For example, a belt is generally used to transmit power from an engine to an auxiliary machine such as an air conditioner compressor mounted on an automobile. The belt tension is kept constant by the auto tensioner. The auto tensioner has a pulley around which the belt is wound around 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. The swing arm is given swing resistance by a friction plate provided in the vicinity of the swing base. This swing resistance attenuates the swing energy of the swing arm.
By such an auto tensioner, it is possible to absorb an attachment 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 fluctuation due to engine rotation fluctuation and the like, prevent belt vibration and noise, and ensure the original life of the belt.
[0003]
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. Eight grooves 10b are provided in the radial direction of one surface of the friction plate 10, and abrasion powder generated from the sliding surface 10a due to wear collects in these grooves 10b as the swing arm swings. It is done.
FIG. 6A is a front view of the holding plate 51 on the fixed side that makes the friction plate 10 slidably contact, and FIG. 6B is a cross-sectional view thereof. The holding plate 51 is a disc-shaped metal plate provided with a plurality of depressions 51a as shown. These indentations 51a are provided to improve the rigidity of the presser plate 51 and to store the wear powder coming out of the friction plate 10 in the same manner as the groove 10b. As shown in FIG. 7A, the friction plate 10 and the pressing plate 51 have a structure in which they are pressed against each other.
[0004]
[Problems to be solved by the invention]
In the conventional auto tensioner as described above, in the case of an engine or the like having a large belt tension fluctuation, if the generated wear powder is large, the depression 51a of the pressing plate 51 may be filled with the wear powder. In such a case, when wear powder further appears, the frictional force between the friction plate 10 and the pressing plate 51 decreases. If the frictional force decreases, the damping effect of the rocking energy decreases.
[0005]
On the other hand, the friction plate 10 is rotated by the swing of the swing arm. In many cases, the amount of rotation is a slight amount of about ± 2 degrees in angle. Accordingly, as shown in FIG. 7B, the friction plate 10 wears while the facing portion 10p of the friction plate 10 facing the depression 51a remains as a gently raised protrusion, and finally the depression 51a. A convex shape that substantially matches the shape of is formed on the friction plate 10. If a large tension fluctuation occurs after the wear has progressed in this way, the facing portion 10p rides from the recess 51a in the circumferential direction, and a gap is formed between the portion other than the facing portion 10p of the friction plate 10 and the pressing plate 51. End up. As a result, the frictional force is greatly reduced and the behavior of the swing arm becomes unstable.
[0006]
In view of the conventional problems as described above, the present invention is an auto that can prevent the phenomenon of riding on the friction plate and stably ensure the damping effect of the rocking energy even when a large amount of wear powder is generated. The purpose is to provide a tensioner.
[0007]
[Means for Solving the Problems]
The auto tensioner of the present invention includes a swing arm that rotatably supports a pulley around which a belt is wound, a support member that rotatably supports the swing arm, and the swing member with respect to the support member. A spring that urges the moving arm in a predetermined swinging direction; and is disposed between the swinging part of the swinging arm and the support member and around the swinging center axis of the swinging arm; A friction plate that imparts a rocking resistance against rocking, and is provided on one side of the rocking portion of the rocking arm and the support member to slide the friction plate, and on the sliding surface side It is formed of a disk-shaped metal plate that is formed only with an annular groove centered on the rocking central axis, and is provided with a through hole for discharging wear powder of the friction plate that has entered the groove. and a friction-plate presser member, the through hole, bottom surface of the groove A first through hole extending from the side to the back side opposite to the sliding contact surface and communicating with the outside, and a pair of opposing surfaces extending radially outward and radially inward from both side portions of the concave groove and communicating with the outside The second through-hole (claim 1).
[0008]
In the auto tensioner configured as described above, only the annular concave groove centered on the swing center axis is formed on the sliding surface side of the friction plate pressing member, so that it faces the groove due to wear. Even if the portion of the friction plate that protrudes from the surroundings, it does not ride on the friction plate pressing member. Therefore, the frictional force is always exerted stably. Further, friction plate wear powder is collected in the groove of the friction plate pressing member and discharged from the first through hole or the second through hole . Therefore, even if there is much abrasion powder, this can be discharged | emitted.
[0009]
Further, in the auto tensioner, a plurality of the first through holes and the second through holes are formed at equal intervals in the circumferential direction of the concave groove and are alternately arranged at different positions in the circumferential direction of the concave groove. (Claim 2). In this case, regardless of the mounting posture of the auto tensioner, the wear powder is discharged from at least one through hole at a position where it is easily discharged.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a comparative example of the present invention, and FIG. 4 shows an embodiment of the present invention. The auto tensioner according to the present invention is the same as the auto tensioner according to FIGS. 1 and 2, except that the presser plate 11 shown in FIG. 4 is mounted instead of the presser plate 11 shown in FIG.
1 and 2 are a sectional view and a side view of an auto tensioner according to a comparative example of the present invention, respectively. In FIG. 1, a pulley 2 around which a belt 1 is wound is provided with a ball bearing 3 at the center thereof. The inner ring of the ball bearing 3 is fitted on the distal end portion 4 a of the swing arm 4 and is fixed to the distal end portion 4 a by a bolt 5 and a nut 6. In this way, the pulley 2 is rotatably supported by the tip portion 4 a of the swing arm 4. Below the swing arm 4, a flange portion 4b and a cylindrical portion 4c are formed integrally with the tip portion 4a.
[0011]
On the other hand, the support member 7 that supports the swing arm 4 is a molded member that includes a support base portion 7a that is hollow inside, a spring receiving portion 7b that is formed around the support base portion 7a, and an attachment portion 7c. is there. The support member 7 is fixed by being fixed to a fixing portion such as a chassis of a vehicle body or an engine by the mounting portion 7c. The outer peripheral surface of the support base 7a has a taper shape slightly tapered to the right in FIG. 1 due to the draft of the mold. A substantially cylindrical bush 8 is mounted on 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.
[0012]
The swing arm 4 is swingable with respect to the support member 7 when the cylindrical portion 4 c is externally inserted into the bush 8. A torsion coil spring 9 is mounted between the spring receiving portion 7 b of the support member 7 and the cylindrical portion 4 c of the swing arm 4. One end 9 a of the torsion coil spring 9 is locked to the support member 7, and the other end 9 b is locked to the swing arm 4.
With the above configuration, the swing arm 4 can swing (turn) 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 urges 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.
[0013]
On the other hand, the annular friction plate 10 is disposed around the oscillation center axis X, is orthogonal to the oscillation center axis X, and is interposed between the flange 4b of the oscillation arm 4 and the pressing plate 11. Yes. The friction plate 10 is made of, for example, a clutch facing material having a thickness of about 3 mm, and includes a sliding surface 10a and a groove 10b as shown in FIG. Further, the inner peripheral shape of the pressing plate 11 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 together (see FIG. 2). The presser plate 11 is fixed by a retaining means (not shown) attached to the screw hole 7d of the support member 7 while being fitted to the support member 7.
[0014]
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 flange 4b and the pressing plate 11 cause the friction plate 10 to move. It is urged so as to push each other in a direction parallel to the oscillation center axis X. A large number of sharp small protrusions (not shown) are provided in the circumferential direction on the surface of the portion of the flange portion 4b that contacts the friction plate 10, and this bites into the friction plate 10 and the friction plate 10b enters the friction plate. 10 is fixed. Assuming that the surface of the friction plate 10 fixed to the flange 4b is the A surface and the back surface thereof is the B surface, the B surface of the friction plate 10 slides against the presser plate 11 by the swing of the swing arm 4. Move. The groove 10b (FIG. 5) is provided on the B surface.
[0015]
3A to 3D show a pressing plate 11 according to a comparative example.
Among them, the (a) is 3, a front view of the pressing plate 11 (the sliding surface side and the front.), (B) is a side view, (c) is a rear view, (d), the ( It is the DD sectional view taken on the line in c). The presser plate 11 is a disk-shaped product obtained by processing a metal plate, and the inner peripheral shape is a chrysanthemum shape and the outer peripheral shape is circular as described above. An annular groove 11b is formed on the sliding contact surface 11a side with the friction plate 10. Only the groove 11b exists as a groove on the sliding surface 11a side. The bottom of the groove 11b is formed with four through holes 11c in the circumferential direction, so to speak, the bottom of the groove 11b is partially removed. The groove 11b of the pressing plate 11 in the state attached to the support member 7 (FIG. 1) is an annular groove centered on the oscillation center axis X (FIG. 1).
[0016]
Next, the operation of the auto tensioner configured as described above will be described with reference to FIGS.
When the tension fluctuation of the belt 1 occurs and the swing arm 4 swings counterclockwise or clockwise in FIG. 2, the collar 4b in FIG. To turn. On the other hand, the holding plate 11 is fixed to the support member 7. Therefore, friction is generated between the friction plate 10 and the pressing plate 11 fixed to the flange 4b by the relative rotation between the pressing plate 11 and the flange 4b. As a result, a swing resistance (friction resistance) is applied to the swing arm 4.
[0017]
The abrasion powder of the friction plate 10 generated by the friction between the friction plate 10 and the pressing plate 11 is collected in the groove 10b (FIG. 5) of the friction plate 10 and discharged from the end of the groove. The wear powder is also collected in the groove 11b of the pressing plate 11 and discharged from the through hole 11c. By discharging from the through hole 11c, the wear powder is not clogged in the groove 11b and can be discharged without any limit. Therefore, even when a large amount of wear powder is generated, such as when the belt tension fluctuation is large, this can be reliably discharged.
Further, the portion of the friction plate 10 facing the groove 11b of the presser plate 11 is not worn, and when the periphery thereof is worn, the portion gradually protrudes from the periphery, but the protruding portion is an annular opening of the groove 11b. Therefore, the friction plate 10 does not run on the holding plate 11 due to the rotation. Therefore, the frictional force is always exerted stably.
In this way, even when a large amount of wear powder is generated, this can be reliably discharged, and the damping effect of rocking energy can be secured stably. Further, since the through holes 11c are equally arranged in the circumferential direction, the wear 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 wear powder is more reliably discharged.
[0018]
Figure 4 is a diagram showing an implementation form of the pressing plate 11 in the auto-tensioner, (a) represents a front view of the pressing plate 11, (b) is a side view, (c) is a rear view, (d ) Is a sectional view taken along line DD in (c).
The difference from FIG. 3 is that, in addition to the through hole 11c at the groove bottom, the through holes 11d are arranged equally on the both side walls of the groove 11b in the circumferential direction and are alternately arranged with the through holes 11c at the groove bottom. It is the point formed as follows. That is, the pressing plate 11 of the present embodiment has a first through hole 11c that extends from the bottom surface portion of the concave groove 11b to the back surface opposite to the sliding contact surface and communicates with the outside, and a diameter from both side surface portions of the concave groove 11b. A pair of opposing second through holes 11d and 11d that extend inward and radially inward and communicate with the outside are provided.
In this case, the wear powder can be discharged also from the second through holes 11d and 11d extending radially inward and outward from both side portions of the concave groove 11b . Furthermore, it is discharged reliably.
[0019]
In addition, in each embodiment of the pressing plate 11 in the auto tensioner, four through holes 11c and 11d are provided, but the number can be increased or decreased as necessary. Even if one piece is effective, in that case, it is considered that if the through hole is not downward when the auto tensioner is attached to the vehicle body, the abrasion powder cannot be quickly discharged to the outside of the holding plate 11. There is a need.
[0020]
In the auto tensioner, the friction plate 10 rotates together with the flange 4b of the swing arm 4 so that the friction plate 10 slides with respect to the pressing plate 11, but conversely, a disk shape without grooves. The pressing plate and the friction plate 10 may be fixed to each other, and a “friction plate pressing member” having a structure similar to that of the pressing plate 11 may be attached to the flange portion 4b and slid with respect to the friction plate 10. . Since the swing arm 4 is generally a die-cast molded product using an aluminum alloy, the flange 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 invention's effect】
The present invention configured as described above has the following effects.
According to the autotensioner of the first aspect, only the annular concave groove centering on the oscillation center axis is formed on the sliding surface side of the friction plate pressing member, so that the friction facing the groove is caused by wear. Even if the portion of the plate protrudes from the surroundings, it does not run on the friction plate pressing member, so that the frictional force is always exerted stably, and the damping effect of the rocking energy can be secured stably. In addition, the friction plate wear powder is collected in the groove of the friction plate pressing member and discharged from the first through hole and the second through hole. it can.
[0022]
According to the auto tensioner of the second aspect, the wear powder is discharged from the at least one through hole at a position where the wear powder is easily discharged regardless of the mounting posture of the auto tensioner. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of an auto tensioner according to a comparative example of the present invention.
FIG. 2 is a side view of the auto tensioner.
3A is a front view of a holding plate according to a comparative example, FIG. 3B is a side view, FIG. 3C is a back view, and FIG. 3D is a cross-sectional view taken along line DD in FIG. .
4A and 4B are diagrams showing a pressing plate according to an embodiment of the present invention, in which FIG. 4A is a front view of the pressing plate, FIG. 4B is a side view, FIG. 4C is a rear view, and FIG. It is the DD sectional view taken on the line in (c).
5 is a perspective view of a friction plate in the conventional and the auto tensioner of FIG. 1; FIG.
6A and 6B are a front view and a cross-sectional view of a holding 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 2 pulley 4 swing arm 4b collar (swing portion)
7 Support member 9 Torsion coil spring 10 Friction plate 11 Holding plate (Friction plate holding member)
11a Sliding surface 11b Groove 11c Through hole 11d Through hole X Oscillation central axis

Claims (2)

A swing arm that rotatably supports a pulley around which a belt is wound at the tip,
A support member for swingably supporting the swing arm;
A spring that biases the swing arm in a predetermined swing direction with respect to the support member;
A friction plate disposed between the swinging portion of the swinging arm and the support member and disposed around the swinging central axis of the swinging arm, and providing a swinging resistance to the swinging of the swinging arm;
Provided on one side of the swinging part of the swinging arm and the support member, the friction plate is slidably contacted, and only the annular concave groove centering on the swinging central axis is provided on the sliding surface side. A friction plate pressing member formed of a disk-shaped metal plate provided with a through hole that is formed and provided with a through hole for discharging the abrasion powder of the friction plate that has entered the concave groove to the outside ,
The through hole extends from the bottom surface portion of the concave groove to the back side opposite to the sliding contact surface and communicates with the outside, and radially outward and radially inner side from both side surface portions of the concave groove. An auto-tensioner comprising a pair of opposed second through holes extending to the outside and communicating with each other . 2. The plurality of first through holes and second through holes are formed at equal intervals in the circumferential direction of the concave groove and are alternately arranged at different positions in the circumferential direction of the concave groove. The described auto tensioner.

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