JP2001153198A - Automatic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent flapping of a belt while maintaining high damping torque. SOLUTION: An auxiliary presser plate 11 having an inclined face 11a in a sawtooth shape and a presser plate 12 having a similar inclined face 12a are arranged so as to mesh with each other, and the auxiliary presser plate 11 and a friction member 10 are sandwiched between a collar part 4b of a rocking arm and the presser plate 12 in a state of being brought into pressure contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art 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 point, and applies tension to the belt by the force of a spring. When a load change on the belt occurs, the swing arm swings and follows the swing. At the time of the swing, a damping torque for the swing is applied, whereby the belt vibration and the like can be prevented.

[0003]

In the above-described conventional auto tensioner, when a load is applied to the belt, the swing arm swings while receiving a high damping torque and effectively consuming energy. However, when the load is released from the belt, the swing arm in the return direction becomes slow due to the high damping torque, and the followability to the belt deteriorates. For this reason, the belt temporarily loosens and flutters, generating noise.

[0004] In view of the above-mentioned conventional problems, an object of the present invention is to provide an auto-tensioner for preventing a belt from fluttering while maintaining a high damping torque.

[0005]

According to the present invention, there is provided an auto-tensioner, comprising: a swing arm which pivotally supports a pulley around which a belt is wound at a tip end; a supporting member which swingably supports the swing arm; In a state where the friction surface is orthogonal to the swing center axis of the swing arm, the swing arm is interposed between the swing portion on the swing arm side and the immovable portion on the support member side, and A friction member that imparts frictional resistance to one of the swinging portion and the non-moving portion and the friction member, and is interposed between the frictional member and one direction of the swinging arm when a load is applied to the belt. A friction member pressing mechanism that extends in a direction parallel to the swing center axis by the swing of the swing arm, and is contractable in a direction parallel to the swing center axis by the swing in the other direction; The oscillating part is urged in the moving direction, and the oscillating part and the immovable part The swinging arm is biased relatively to the support member so as to approach each other in a direction parallel to the direction of movement, so that the friction member and the friction member pressing mechanism are pressed against each other so that the swing portion and the immovable And a biasing means to be sandwiched between the first and second parts.

In the auto tensioner configured as described above, when a load is applied to the belt, the swinging arm is swung in one direction, so that the friction member pressing mechanism extends in a direction parallel to the swing center axis. Therefore, the friction member and the friction member pressing mechanism sandwiched between the swinging portion and the immovable portion are strongly pressed against each other, and a large damping torque is applied to the swinging arm. On the other hand, when the load on the belt is released, the swinging arm swings in the other direction, so that the friction member pressing mechanism contracts in a direction parallel to the swing center axis. Therefore, the force for pressing the friction member and the friction member pressing mechanism against each other is weakened, and the damping torque applied to the swing arm is reduced.

In the above-mentioned auto tensioner, the friction member pressing mechanism may be configured such that two annular bodies having inclined surfaces inclined in the circumferential direction are formed on one surface of the ring member so that the inclined surfaces coincide with each other. They may be abutted in parallel directions (claim 2). In this case, when a load is applied to the belt, one of the slopes moves in the direction of ascending the other slope by swinging in one direction of the swing arm. Thereby, the dimension in the direction parallel to the swing center axis occupied by both annular bodies increases. Therefore, the friction member and the friction member pressing mechanism sandwiched between the swinging portion and the immovable portion are strongly pressed against each other, and a large damping torque is applied to the swinging arm. On the other hand, when the load on the belt is released, the swing arm moves in the other direction by swinging the swing arm in the other direction. Thereby, the dimension in the direction parallel to the swing center axis occupied by the two annular members is reduced. Therefore, the force for pressing the friction member and the friction member pressing mechanism against each other is weakened, and the damping torque applied to the swing arm is reduced.

[0008]

3 and 4 are a sectional view and a side view, respectively, of an auto-tensioner according to an embodiment of the present invention. In FIG. 3, 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 4 a of the swing arm 4, and is fixed to the tip 4 a by a washer 5 and a bolt 6. As a result, the pulley 2 is rotatably held around the tip 4a of the swing arm 4 as a support shaft. The swing arm 4 is integrally formed with the distal end portion 4a,
And a cylindrical portion 4c.

On the other hand, the support member 7 has a cavity 7a therein.
It is a molded member having a spring receiving portion 7b, a screw hole 7c, and a support base 7d around the screw hole 7c. A pair of mounting portions 7e (FIG. 4) are provided on side surfaces. The support member 7 is fixed by being fixed to a fixed portion such as a chassis or an engine of the vehicle body by the mounting portion 7e. The outer peripheral surface of the support base 7d has a tapered shape that tapers slightly to the right in FIG. 3 due to the draft of the mold. A substantially cylindrical bush 8 is mounted on the outer peripheral surface of the support base 7d. The bush 8 is a resin (eg, nylon) having a hardness of HRR 90 to 95.

The swing arm 4 is swingable with respect to the support member 7 when its cylindrical portion 4c is inserted outside the outer peripheral surface of the bush 8. Also, the spring receiving portion 7 of the support member 7
A torsion compression spring 9 is mounted between the swing arm 4 and the flange 4b of the swing arm 4. One end 9 a of the torsion compression spring 9 is locked by the support member 7, and the other end 9 b is locked by the lower part of the swing arm 4. The torsion compression spring 9 is configured such that the end 9b biases the swing arm 4 in the clockwise direction in FIG.
It is locked in a state of being charged in the winding direction against the torsion resistance. Therefore, the belt 1 is given a constant tension. With the above configuration, the swing arm 4 can swing (rotate) within a predetermined range with respect to the support member 7 as a fixed member via the bush 8. At this time, the swing base is the cylindrical portion 4c, and the swing center axis X is on the center axis of the support base 7d (or the fixing screw 13 described later).

On the other hand, the annular friction member 10 is interposed between the flange 4b of the swing arm 4 and the holding plate 12 with the friction surface S perpendicular to the swing center axis X. The friction member 10 is attached to the flange 4b while being prevented from rotating in the circumferential direction, and swings integrally with the flange 4b. The annular or disk-shaped holding plate 12 is mounted on the support member 7 so as to prevent rotation, and is fixed by a fixing screw 13 screwed into a screw hole 7c of the support member 7. Between the holding plate 12 and the friction member 10,
An auxiliary holding plate 11 made of an annular metal plate is sandwiched. By holding the auxiliary holding plate 11 and the friction member 10 between the holding portion 12 and the flange portion 4b urged by the torsion compression spring 9 to approach each other in a direction parallel to the swing center axis X. , Friction member 10 and auxiliary holding plate 11
Are in pressure contact with each other.

The above pressure contact structure will be described in more detail. FIG. 1 is a partial cross-sectional view of a cross section in the circumferential direction of a portion A shown in FIG. FIG. 2 is a perspective view showing the auxiliary holding plate 11 alone. As shown in FIG. 2, the surface of the auxiliary holding plate 11 on the side in contact with the holding plate 12 has a saw-tooth shape over the entire circumference, thereby forming a plurality of slopes 11 a inclined in the circumferential direction. Have been. Similarly, on the surface of the holding plate 12 on the side in contact with the auxiliary holding plate 11, a saw-tooth shape is formed over the entire circumference, and thereby a plurality of slopes 12a inclined in the circumferential direction are formed ( (Fig. 1). The holding plate 12 and the auxiliary holding plate 11 are arranged so as to abut each other in a direction parallel to the swing center axis X, and are engaged with each other so that the saw teeth are engaged with each other. As shown in FIG. 1, the two slopes 11a and 12a are in contact with each other with a slight gap therebetween. The slopes 11a and 12a are provided with a coating to reduce the coefficient of friction.
Is sufficiently smaller than the friction coefficient. The pressing plate 12 and the auxiliary pressing plate 11 constitute a friction member pressing mechanism for the friction member 10 by an operation described later.

Next, the operation of the auto-tensioner configured as described above will be described with reference to FIGS.
When the load on the belt 1 fluctuates due to the operation of the accessory and the swing arm 4 swings counterclockwise in FIG. 4, the flange 4 b as a “swing portion” in FIG. The friction member 10 moves upward in the figure. Therefore, the auxiliary holding plate 11 that is in pressure contact with the friction member 10 also attempts to follow the friction member 10. On the other hand, the holding plate 12 as an “immobile portion” is fixed, and the friction coefficient between the slope 11 a and the slope 12 a is determined by the friction member 10 and the auxiliary holding plate 1.
Because the friction coefficient is sufficiently smaller than the coefficient of friction of 1, the slope 11a slides relatively upward (upward) on the slope 12a before the friction member 10 slides on the auxiliary holding plate 11. As a result, the auxiliary holding plate 11 opposes the torsion compression spring 9 (FIG. 3), and is relatively left with respect to the holding plate 12 in the left direction of FIG. 1 (or FIG. 3) (the direction parallel to the swing center axis X). ), And the auxiliary holding plate 11 and the friction member 10 are strongly pressed against each other. When the upward moving force of the friction member 10 overcomes the static friction force due to the pressure contact, the friction member 10 slides upward with respect to the auxiliary holding plate 11. Even during sliding, the friction member 10 is in a state of being pressed against the auxiliary holding plate 11 in the same manner, and the swing arm 4 is given swing resistance (friction resistance). Therefore, the swing energy of the swing arm 4 is consumed as heat due to friction.

Conversely, when the load on the belt 1 is released and the belt 1 is loosened, the swing arm 4 swings clockwise in FIG. Thereby, the flange 4b and the friction member 10 in FIG. 1 move downward in the figure. Therefore, the auxiliary holding plate 11 that is in pressure contact with the friction member 10 also attempts to follow the friction member 10. On the other hand, the holding plate 12 is fixed and the coefficient of friction between the slopes 11a and 12a is sufficiently smaller than the friction coefficient between the friction member 10 and the auxiliary holding plate 11, so that the friction member 10 Before sliding against
The direction in which the slope 11a relatively descends the slope 12a (downward)
Slip on. As a result, the auxiliary holding plate 11 is
Under the bias of (FIG. 3), it moves to the right of the drawing (in a direction parallel to the swing center axis X) relative to the holding plate 12, and the auxiliary holding plate 11 and the friction member 10 are mutually moved. The pressing force is weak. When the force by which the friction member 10 moves downward overcomes the static friction force caused by the weak pressure contact, the friction member 1
0 slides downward with respect to the auxiliary holding plate 11. During this sliding, the force for pressing the friction member 10 against the auxiliary holding plate 11 is weak, and the swing resistance applied to the swing arm 4 is small.

As described above, when a load is applied to the belt 1 by driving the accessory, a large swing resistance is applied to the swing arm 4, and the swing damping torque increases. Also, when the load is released and the belt 1 is slackened, only a small swing resistance is applied to the swing arm 4, and the swing damping torque is reduced. That is, directionality is given to the generation of the damping torque, and a high damping torque is secured when necessary.
When not needed, the damping torque is low. Due to the low damping torque when the load on the belt 1 is released, the swing arm 4 quickly follows the slack of the belt 1 and does not cause the belt 1 to flutter.

The above embodiment has a structure in which the pressing force obtained from the torsional compression spring 9 is controlled by the movement of the auxiliary holding plate 11 in the direction of the pivot center axis. When a high damping torque is required, the auxiliary holding plate 11 Moves torsion compression spring 9
Is further compressed. Therefore, the spring force required for the torsion compression spring 9 itself can be reduced to some extent.

In the above-described embodiment, the auxiliary holding plate 11 and the holding plate 12 have relatively simple structures (saw-tooth shape) of the mutually engaging portions and are robust. Moreover, since the inclined surfaces 11a and 12a are formed in a saw-tooth shape over the entire circumference, the engagement is not released once the engagement surfaces are arranged and pressed. Therefore, a guide member or the like for maintaining the engaged state is not required. This is a preferable configuration in that the auxiliary holding plate 11 in a free state that is not fixed to the holding plate 12 or the friction member 10 is stably held. However, when a guide member or the like for maintaining the engagement state is separately provided, the serrated slopes 11a and 12a are not necessarily provided over the entire circumference.
Further, instead of the slopes 11a and 12a, a similar friction member pressing mechanism (for example, one using a cam, one using a pin and a groove, engagement between three-dimensional curved surfaces, and the like) can be configured. In short, a mechanism may be provided in which a displacement in a direction parallel to the swing center axis is caused by a force of one moving in the circumferential direction with respect to the other.

In the above-described embodiment, the friction member 10 is fixed to the flange 4b, and the friction member 10 and the auxiliary holding plate 11 are in a slidable relationship with each other. 11, the flange portion 4b and the friction member 10 may be in a slidable relationship with each other. Further, in the above embodiment, the friction member 10 is on the swing side,
The auxiliary holding plate 11 is engaged with the holding plate 12 on a slope, but the relationship may be reversed. That is, a slope may be provided on the flange 4b instead of the holding plate 12, and the flange 4b and the auxiliary holding plate 11 may be engaged with each other on the slope, and the friction member 10 may be attached to the holding plate 12 (FIG. 1). Is rotated 180 degrees, and corresponds to a state in which a flange portion 4b, an auxiliary pressing plate 11, a friction member 10, and a pressing plate 12 are formed in this order from the left.)

[0019]

The present invention configured as described above has the following effects. According to the auto tensioner of claim 1,
When a load is applied to the belt, the friction member holding mechanism extends in the direction parallel to the swing center axis, and the friction member and the friction member holding mechanism are strongly pressed against each other, so that a large damping torque is applied to the swing arm. can do. On the other hand, when the load on the belt is released, the friction member pressing mechanism contracts in a direction parallel to the swing center axis, and the force of pressing the friction member and the friction member pressing mechanism against each other is weakened. It is smaller and the swing arm can quickly follow the belt. Therefore, it is possible to prevent the belt from fluttering.

According to the second aspect of the present invention, when a load is applied to the belt, the size of the two annular members in the direction parallel to the swing center axis increases, so that the friction member and the friction member pressing mechanism are mutually separated. Since it is strongly pressed, a large damping torque can be applied to the swing arm. On the other hand, when the load on the belt is released, the size in the direction parallel to the swing center axis occupied by the two annular members decreases, and the force of pressing the friction member and the friction member pressing mechanism against each other is weakened. Is smaller and the swing arm can quickly follow the belt. Therefore, it is possible to prevent the belt from fluttering. Also, the configuration to provide the slope,
Structurally simple and robust.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing an auxiliary holding plate of the auto tensioner.

FIG. 3 is a cross-sectional view showing an entire configuration of the auto tensioner.

FIG. 4 is a side view of the auto tensioner.

[Explanation of symbols]

 Reference Signs List 1 belt 2 pulley 4 swing arm 4a tip 4b flange 7 support member 9 torsion compression spring 10 friction member 11 auxiliary holding plate 12 holding plate S friction surface X swing center axis

Claims (2)

[Claims] An oscillating arm that supports a pulley around which a belt is wound at a distal end thereof; a support member that oscillates the oscillating arm; and a friction surface on an oscillating center axis of the oscillating arm. In a state of being orthogonal, a friction member interposed between the swinging portion on the swing arm side and the immovable portion on the support member side, and imparting frictional resistance to the swinging of the swing arm, Interposed between any one of the swinging portion and the immovable portion and the friction member, the swinging arm swings in one direction when a load is applied to the belt and is parallel to the swinging center axis. And a friction member pressing mechanism that can contract in a direction parallel to the swing center axis by swinging in the other direction, and biasing the swing arm in a predetermined swing direction,
The friction member and the friction member urge the swing arm relative to the support member such that the swing portion and the immovable portion approach each other in a direction parallel to a swing center axis. An auto-tensioner comprising: urging means for holding a holding mechanism between the swinging portion and the immovable portion in a pressure-contact state with each other. 2. The friction member pressing mechanism includes: a pair of annular members having inclined surfaces inclined in a circumferential direction formed on one surface in a direction parallel to the swing center axis so that the inclined surfaces match each other; The auto-tensioner according to claim 1, wherein the auto-tensioner is abutted.