JP2003207000A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic tensioner in which capability of dampening oscillating energy is improved with a simple constitution. <P>SOLUTION: In this automatic tensioner, in addition to a first friction member 10 for applying oscillation resistance to an oscillating arm 4, a second friction member 12 is attached between lines of a helical torsion coil spring 9 for energizing the oscillating arm 4. The second friction member 12 is an annular body which is cut off at one point in the circumferential direction, held between the lines after being deformed as a spring washer and brought into contact with the line of the helical torsion coil spring 9 at its both faces. Relative torsion is generated between the lines of the helical torsion coil spring 9 by oscillation of the oscillating arm 4, by which friction is generated between the line and the second friction member. <P>COPYRIGHT: (C)2003,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 about a fixed point, 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.

[0003]

In the conventional autotensioner as described above, the swinging arm subjected to the belt tension fluctuations swings swinging energy into heat by the swinging resistance and consumes it. , Quickly dampen oscillations.
However, in recent years, an automobile engine having a rotation fluctuation larger than that of a conventional one has appeared, and as a result, rocking energy has increased. When a conventional auto tensioner is used for such an engine, the friction plate wears faster than before and the service life is shortened. Increasing the size of the friction plate or making it a complicated structure against these problems is
It is not a good idea because it goes against compactness and cost reduction.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide an autotensioner having a simple structure and improved ability to damp swing energy.

[0005]

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 first friction member interposed between a swinging portion on the swinging arm side and a non-moving portion on the supporting member side to impart swinging resistance to swinging of the swinging arm; The arm is twisted and biased in a predetermined swing direction, and the swing arm is swung with respect to the support member so that the swing portion and the immovable portion press each other with the first friction member interposed therebetween. It is provided with a torsion coil spring that urges in the direction of the dynamic center axis, and a second friction member that is sandwiched between the lines of the torsion coil spring and that causes friction due to relative twist between the lines (claim 1). .

In the automatic tensioner having the above-described structure (claim 1), the first friction member imparts the first swing resistance to the swing of the swing arm, and the twist based on the swing is applied. Twisting of the coil spring causes relative twisting between the wires, which causes friction with the second friction member sandwiched between the wires. This is the second swing resistance. As a result, a larger swing resistance is given to the swing arm as compared with the case where only the first swing resistance is used. Further, since the second friction member can be attached only by sandwiching it between the torsion coil springs, there is no need for a separate attachment member or the like.

In the above automatic tensioner (Claim 1), the second friction member is an annular body which is cut at one location in the circumferential direction and is deformed according to the linear shape of the torsion coil spring. (Claim 2). In this case, the original shape of the second friction member is a simple shape that is easy to manufacture.

Further, the auto tensioner (claim 1).
In the above, the second friction member may be locked to the torsion coil spring and may be externally inserted to the tubular portion that is the swing base portion of the swing arm (claim 3). In this case, the torsion coil spring supports the second friction member, and the second friction member supports the tubular portion.

[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, the support member 7 is a molding member having a support base portion 7a having a hollow inside, a spring receiving portion 7b formed around the support base portion 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 via the bush 8 with respect to the support member 7 that is a fixed member. 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, an annular first friction member 10 (friction plate)
Is orthogonal to the swing center axis X and is interposed between the collar portion 4b of the swing arm 4 and the annular pressing plate 11. First
The friction member 10 is made of, for example, a clutch facing material. Further, the inner peripheral shape of the pressing plate 11 and the support member 7
The right end side (FIG. 1) of the outer peripheral shape has a chrysanthemum-shaped detent structure that fits with each other (see FIG. 2). Then, the pressing plate 11 is fixed to the support member 7 by a retaining means (not shown) attached through the screw hole 7d of the support member 7 while being fitted to the support member 7. Torsion coil spring 9
Urges the oscillating arm 4 against the support member 7 by the elastic force in the oscillating central axis X direction, so that the collar portion 4b and the pressing plate 11 sandwich the first friction member 10. , Are urged to push each other in a direction parallel to the swing center axis X.

A second friction member 12 is mounted between the lines of the torsion coil spring 9 shown in FIG. FIG. 3 is a view showing the second friction member 12 alone, (a) is a front view, and (b) is a side view (bottom) and a cross-sectional view (top).
The second friction member 12 is an annular body cut at one position in the circumferential direction. The material of the second friction member 12 is, for example, a resin having a certain heat resistance, wear resistance and elasticity. When the second friction member 12 is attached to the torsion coil spring 9, the second friction member 12 is twisted in the axial direction at the cut portion, so that the second friction member 12 can have a form like a spring washer.

The outer diameter of the second friction member 12 is larger than the ring diameter of the torsion coil spring 9 mounted as shown in FIG. 1, and the inner diameter is smaller than the ring diameter of the torsion coil spring 9. In addition, the inner diameter is designed to be externally inserted into the tubular portion 4c of the swing arm 4 without a gap when mounted, and to be slidable in the axial direction with respect to the tubular portion 4c. . In FIG.
On both side surfaces of the second friction member 12, there are formed recesses 12a that are continuous in the circumferential direction and are engaged with the lines of the torsion coil spring 9. The shape of the recess 12a seen in the cross section shown in (b) is generally arcuate, but it does not fit the line of the torsion coil spring 9 exactly, and even if the line of the torsion coil spring 9 is received, it is still a little. It is large enough to play. The axial width of the second friction member 12 in the cross section shown in (b) is wider on the inner diameter side than on the outer diameter side.

The thickness of the thinnest portion of the second friction member 12 (bottom of the recess 12a) is determined in consideration of the axial gap between the torsion coil springs 9 mounted as shown in FIG. Thus, it is designed to be sandwiched between the wires in the mounted state, and to be always in contact with both wires regardless of the rocking position of the rocking arm 4. FIG. 4 is a perspective view showing a state in which the second friction member 12 is sandwiched between the lines of the torsion coil spring 9. In order to sandwich the second friction member 12 in this manner, the second friction member 12 twisted like a spring washer is inserted from one axial end side of the torsion coil spring 9 while rotating.
Then, the torsion coil spring 9 with the second friction member 12 sandwiched in this way is mounted as shown in FIG. When the second friction member 12 is mounted, the second friction member 12 is externally inserted into the cylindrical portion 4c of the swing arm 4 without a gap, so that the second friction member 12 can be stably positioned in the radial direction.

Next, the operation of the auto tensioner configured as described above will be described with reference to FIGS.
When the swinging arm 4 swings in the counterclockwise direction or the clockwise direction in FIG. 2 due to the change in tension of the belt 1, the collar portion 4b in FIG. Turn to. 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 11
Due to the relative rotation between the and the collar portion 4b, friction is generated in the first friction member 10 in a state of being pressed against them. As a result, the swing arm 4 has a first swing resistance (friction resistance).
Is given.

Further, the torsion coil spring 9 engaged with the swing arm 4 at the end portion 9b is twisted in a direction in which the diameter is reduced or expanded, and a relative twist is generated between the respective lines. Therefore, the second friction member 12 that is in contact with both adjacent lines
Has a relative sliding contact with these lines in the circumferential direction and causes friction. In addition, the wire is slightly moved in the radial direction due to the contraction or expansion. Therefore, the line and the recess 12a
Friction also occurs in the radial direction between and. As a result, the swing arm 4 is provided with a second swing resistance (friction resistance) based on the second friction member 12, and an excellent damping effect is obtained. Further, when the diameter is reduced, the spring strongly tightens the second friction member 12 inward in the radial direction, so that the contact pressure increases and the damping effect sharply increases.

As described above, the first swing resistance and the second swing resistance impart a larger swing resistance to the swing arm 4 as compared with the case where only the first swing resistance is used. Therefore,
Even if the tension variation of the belt 1 is large due to the engine having a large rotation variation, the swing energy can be quickly attenuated while suppressing the progress of wear of the friction members 10 and 12. Further, since the frictional force can be shared between two places, the load on the first friction member 10 becomes relatively small when applied to an engine in which the fluctuation in tension is not so large. Therefore, an inexpensive resin can be used as the material of the first friction member 10 instead of the expensive clutch facing material, and the cost can be reduced.

Since the original shape of the second friction member 12 is a simple shape, it can be manufactured at low cost. Further, since the mounting of the second friction member 12 as described above is only required to be sandwiched between the torsion coil springs 9, there is no need for a separate mounting member or the like, and the structure is simple. Further, the second friction member 12 is externally inserted into the tubular portion 4c, and the second friction member 1
Since 2 is engaged with the torsion coil spring 9, the torsion coil spring 9 supports the second friction member 12, and the second friction member 12 supports the tubular portion 4c. As a result, the axis of the tubular portion 4c is tilted so that the upper portion of the swing arm 4 is located in the position shown in FIG.
It is possible to prevent it from leaning to the left or right.

In the above embodiment, the second friction member 1
Although one 2 is mounted, if a plurality of 2 are mounted, the second swing resistance can be further increased. That is, the damping capacity can be adjusted by the number of the second friction members 12 mounted. Further, in the above embodiment, the inner peripheral surface of the second friction member 12 is brought into contact with the cylindrical portion 4c of the swing arm 4, but this does not necessarily have to be in contact. For example, instead of the inner peripheral surface, the outer peripheral surface may be brought into contact with the outer member, or may be brought into contact with neither member and floated together with the torsion coil spring 9. However, in these cases, the function of supporting the tubular portion 4c via the second friction member cannot be obtained. Further, in the above-described embodiment, the concave portion 12a (FIG. 3) of the second friction member 12 mounted on the torsion coil spring 9 has a play with respect to the line, but the cross-sectional shape is made to match the line shape. Good. However, in this case, since there is no play, it is difficult to mount. Further, since the second friction member follows the expansion and contraction of the wheel diameter due to the twist, and there is no radial sliding contact between them, friction in the radial direction cannot be expected.

[0021]

The present invention constructed as described above has the following effects. According to the auto tensioner of claim 1,
The first friction member imparts a first swinging resistance to the swinging of the swinging arm, and the twisting of the twisted coil spring based on the swinging causes a relative twist between the wires, and the wire is sandwiched between the wires. Also, friction is generated between the second friction member and the second friction member, which serves as second swing resistance. Therefore, a larger swing resistance is imparted to the swing arm as compared with the case where only the first swing resistance is used, and the ability to attenuate the swing energy is improved. Further, since the second friction member can be attached only by sandwiching it between the torsion coil springs, a separate attachment member or the like is not required and the structure is simple. Thus, with a simple structure, it is possible to provide an autotensioner having an improved ability to damp swing energy.

According to the automatic tensioner of the second aspect, since the original shape of the second friction member is a simple shape, it can be manufactured at low cost.

According to the autotensioner of the third aspect, since the torsion coil spring supports the second friction member and the second friction member supports the tubular portion, the axis of the tubular portion tilts and rocks. It is possible to prevent the moving arm from tilting.

[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.

FIG. 3 is a view showing a second friction member of the auto tensioner as a single body, (a) is a front view, and (b) is a side view (bottom) and a cross-sectional view (top).

FIG. 4 is a perspective view showing a state in which the second friction member is attached to a torsion coil spring.

[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 First friction member 11 Presser plate (immovable part) 12 Second friction member X swing center axis

Claims (3)

[Claims] 1. A swing arm that rotatably supports a pulley around which a belt is wound, a support member that swingably supports the swing arm, and a swing portion on the swing arm side. A first friction member that is interposed between the immovable portion on the support member side and imparts a swing resistance to the swing of the swing arm; and a biasing force that twists the swing arm in a predetermined swing direction. In addition, the torsion coil spring biases the swing arm in the swing center axis direction with respect to the support member so that the swing portion and the immovable portion press each other with the first friction member interposed therebetween. And an second friction member that is sandwiched between the lines of the torsion coil spring and that causes friction due to relative twist between the lines. 2. The auto according to claim 1, wherein the second friction member has an original shape of an annular body which is cut at one position in the circumferential direction and is deformed according to the linear shape of the torsion coil spring. Tensioner. 3. The automatic tensioner according to claim 1, wherein the second friction member is locked to the torsion coil spring and is externally fitted to a cylindrical portion which is a swing base portion of the swing arm.