JPH0821497A - Auto-tensioner - Google Patents

Abstract

PURPOSE:To absorb the belt vibration energy in a stable manner by elastical deforming an urging member in the swing center axis direction, each fitting a supporting member and a swing arm in the state where the relative turn around the axis is regulated. CONSTITUTION:A swing arm 1 which is constituted so that a pulley 11 for laying a belt is installed at a top end part 1a, and a swing shaft 12 is fixed on a basic part 1b is supported by an urging member 3 interposed between the swing shaft 12 and a supporting member 2. The urging member 3 consists of an elastomer, and press-fitted between the outer periphery of the swing shaft 12 and the inner periphery of the supporting member 2, and turn is regulated by the engagement projection 26 of the supporting member 2. The urging member 3 is elastically deformed so that the shearing stress F acts in the direction set along the turning center axis L in the press-fitted state, and the swing arm 1 is press-attached on the frictional member 4 by the restoration force, and the vibration energy of the belt can be absorbed by the frictional force accompanied with the press contact between the swing arm 1 and the frictional member 4.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, for example, an alternator for an automobile,
An auto tensioner is used to keep the tension of a belt wound between a plurality of auxiliary machines such as a cooler pump and a power steering pump constant. As this autotensioner, there is provided one that absorbs the vibration energy of the belt by the deformation action of the elastomer. However, although this type of autotensioner has a simple structure and can be made lightweight, it only absorbs the vibration energy of the belt by utilizing only the hysteresis loss due to the deformation of the elastomer, so its energy absorption effect is small. However, there is a problem that so-called belt squeal is likely to occur.

Therefore, there is also provided an automatic tensioner which absorbs the vibration energy of the belt by utilizing a friction damping action (see, for example, Japanese Patent Application Laid-Open No. 2-186155). In this auto tensioner, as shown in FIG. 8, a swing arm 92 having a pulley 91 attached to its tip is allowed to move in the axial direction with respect to a swing shaft 94 fixed to a support member 93. In this state, the flat flange portion 9 is rotatably attached and integrally formed with the swing shaft 94.
An annular friction member 97 is interposed between the movable member 5 and the flat base portion 96 of the swing arm 92. Further, between the support member 93 and the swing arm 92, an annular urging member 9 having a structure in which an elastomer 98b is sandwiched between metal plates 98a.
8 are tightly compressed in the width direction by a predetermined amount.

According to the above automatic tensioner, the swing arm 92 is moved to the friction member 9 by the compression resistance of the biasing member 98.
It is possible to apply a predetermined frictional force (swing resistance) to the swing arm 92 by bringing it into pressure contact with 7, and thereby to absorb the vibration energy of the belt. Further, the swinging resistance of the swinging arm 92 can be biased in a predetermined direction by the twisting resistance of the biasing member 98, whereby the belt can be pressed with a predetermined pressure.

[0005]

In the autotensioner having the above-mentioned structure, the elastomer 98 forming the biasing member 98.
Since the swing arm 92 is brought into pressure contact with the friction member 97 only by the compression resistance of b, an error in the width dimension of the biasing member 98, a change in the width dimension due to the torsional deformation of the biasing member 98, and a support. The pressure contact force between the swing arm 92 and the friction member 97 is likely to change due to the influence of the axial assembly error of the member 93. In particular, in order to exert the desired energy absorption effect, it is necessary to increase the axial pressure contact force of the elastomer 98b.
The fact that the rigidity of the elastomer 98b in the axial direction is extremely high in combination with the fact that the thickness is small, the above-mentioned change in the pressure contact force is remarkable with respect to a slight axial displacement or error of the biasing member 98 or the supporting member 93. Will appear in. For this reason, there are problems that the initial characteristics greatly vary, the friction damping characteristics easily change over time, the energy absorption effect on the vibration of the belt fluctuates, and the tension applied to the belt becomes unstable. there were.

The present invention has been made in view of the above problems, and it is possible to stably absorb the vibration energy of the belt and to stably apply a desired tension to the belt. The purpose is to provide an auto tensioner.

[0007]

In order to achieve the above object, an automatic tensioner according to a first aspect of the present invention comprises an oscillating arm having a pulley attached to its tip, and the oscillating arm being oscillatably and oscillating. A support member movably supported along the central axis, a friction member interposed between the swing arm and the support member, and an annular ring made of an elastomer arranged coaxially with the swing center axis of the swing arm. Urging member, and by virtue of the axial deformation resistance of the urging member, the swing arm is brought into pressure contact with the support member via the friction member or the friction member to impart rotation resistance to the swing arm. , In an automatic tensioner that biases the swing arm in a predetermined direction by twisting resistance of the bias member, shear stress is generated in the bias member in a direction along the swing center axis of the swing arm. Elastically deformed like And while regulating the relative rotation to the swing center axis, and is characterized in that fitted to each of the supporting members and the oscillating arm.

The autotensioner according to a second aspect is the autotensioner according to the first aspect, wherein metal rings are fixed to the inner periphery and the outer periphery of the biasing member, and the metal rings are attached to the swing center shaft. The present invention is characterized in that the support member and the swing arm are fitted to each other with a gap provided therebetween in a state in which relative rotation around them is restricted.

[0009]

According to the automatic tensioner of the first aspect, the swing arm is caused to move through the friction member or the friction member by the elastic restoring force corresponding to the shear stress in the direction along the swing center axis of the biasing member. It can be pressed against the support member.
Therefore, the rigidity of the biasing member in the axial direction can be reduced as compared with the conventional one in which the pressing force is applied only by the compression resistance, and the rigidity and the displacement of the biasing member and the supporting member in the axial direction are accordingly reduced. Therefore, it is possible to suppress a large change in the pressure contact force. Further, according to the autotensioner according to the second aspect, by simply inserting the metal rings fixed to the inner circumference and the outer circumference of the biasing member into the support member and the swing arm, respectively, the biasing member is supported. And the swing arm.

[0010]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of the auto tensioner of the present invention. In this auto tensioner, a belt winding pulley 11 is attached to a tip portion 1a and a swing shaft 12 is fixed to a base portion 1b, and a swing shaft 12 of the swing arm 1 is rotated. A supporting member 2 that freely supports and a biasing member 3 that is interposed between the swing shaft 12 and the supporting member 2 constitute a main part.

A shaft 13 is attached to the tip portion 1a of the swing arm 1.
The pulley 11 is rotatably supported on the shaft 13 via a bearing 14. Also,
The swing shaft 12 has a cylindrical shaft portion 12a having a rectangular cross-section fitting portion 12b formed at one end and a disc-shaped flange portion 12c formed at the other end. Joint section 12
By fitting b into the fitting hole 15 of the rectangular cross section formed in the base 1b of the swing arm 1 and caulking the tip, the rotation center axis L is rotated with respect to the base 1b of the swing arm 1. Is fixed in a state in which the rotation of is restricted.

The support member 2 is formed by integrally molding a flange portion 22 for fixing the support member 2 to a fixed portion A such as an engine on the opening side of a tubular portion 21 having a side wall 21a. A short tubular portion 23 is formed at the center of the side wall 21a of the tubular portion 21, and with respect to the short tubular portion 23,
The shaft portion 12a of the swing shaft 12 is rotatably fitted through a bush 24 made of a resin such as nylon. Further, the inner circumference of the tubular portion 21 is formed on a circumferential surface concentric with the rotation center axis L, and the collar portion 12c of the swing shaft 12 is formed on the inner circumference on the opening side thereof. , Is rotatably fitted through a bush 25 made of resin such as nylon.
Further, an annular friction member 4 is interposed between the outer surface of the side wall 21a of the tubular portion 21 and the base portion 1b of the swing arm 1. The friction member 4 is a flat member made of resin or the like, and the inner circumference thereof is the short tubular portion 23 of the support member 2.
And the friction surface is orthogonal to the rotation center axis L.

The swing shaft 12 is fitted to the support member 2 in a state of being movable along the rotation center axis L. In addition, an engagement protrusion 26 for restricting the rotation of the urging member 3 is formed on the inner circumference of the cylindrical portion 21. The engagement protrusions 26 are rib-shaped and extend in the axial direction, and a plurality of engagement protrusions 26 are formed at predetermined intervals along the circumferential direction (see FIG. 2). Further, a stopper S for abutting the locking projection 16 of the swing arm 1 against a predetermined portion of the outer periphery of the support member 2 to restrict the swing arm 1 from rotating more than necessary.
Is protruding.

The biasing member 3 is a cylindrical member made of an elastomer such as synthetic rubber or synthetic resin, and is press-fitted between the outer circumference of the swing shaft 12 and the inner circumference of the support member 2. In the press-fit state, the biasing member 3 is elastically deformed in the axial direction so that the shear stress F acts in the direction along the rotation center axis L, and the restoring force against the elastic deformation causes the swing arm to move. 1 is brought into pressure contact with the friction member 4. That is, in the free state, the biasing member 3 has both end surfaces inclined with respect to the rotation center axis L (see FIG. 3), and the inner peripheral side thereof is the shaft portion 12 a of the swing shaft 12. The urging member 3 is press-fitted into the inner periphery of the support member 2 while the relative rotation with the shaft portion 12a is regulated, and the tip end side of the swing shaft 12 of the support member 2 is pressed. The short shaft portion 23 is fitted (see FIG. 4), and in this state, the swing shaft 12 is attached to the support member 2.
Of the urging member 3 until the both end surfaces of the urging member 3 become substantially perpendicular to the rotation center axis L.
Is elastically deformed in the axial direction and the radial direction to apply shear stress F in the direction along the rotation center axis L, and the elastic restoring force corresponding to the shear stress F causes the swinging arm 1 to move the friction member. It is pressed against 4. A plurality of engagement grooves 31 that engage with the engagement protrusions 26 of the support member 2 are formed on the outer circumference of the biasing member 3 (see FIG. 2).

Since the autotensioner having the above-mentioned structure absorbs the vibration energy of the belt by the frictional force caused by the pressure contact between the swing arm 1 and the friction member 4, the above-mentioned energy can be obtained only by the hysteresis loss of the conventional elastomer. It is possible to exert a more excellent energy absorption effect as compared with the one that absorbs. Also, the biasing member 3
Since the rocking arm 1 is pressed against the friction member 4 by utilizing the elastic restoring force corresponding to the shear stress F, the rigidity of the biasing member 3 in the axial direction can be reduced. Therefore, the swing arm is caused by an error in the width dimension of the biasing member 3, an axial displacement due to the torsional deformation of the biasing member 3, an axial error in the portion in which the biasing member 3 is incorporated, and the like. It is possible to suppress a large change in the pressure contact force between the support member 1 and the support member 2.
As a result, it is possible to suppress variations in the initial set load on the belt and changes in the friction damping characteristics over time, which in turn can absorb the vibration energy of the belt in a stable manner and On the other hand, a desired tension can be stably applied.

FIG. 5 is an enlarged sectional view showing another embodiment of the biasing member 3. In this embodiment, the biasing member 3
Metal rings 51 and 52 are integrated with each other on the inner circumference and the outer circumference by bonding or the like. Of the above metal rings 51, 52,
The metal ring 51 on the outer peripheral side has an engagement groove 51a extending in the axial direction.
Are formed in plural, and the relative rotation of both is restricted by engaging the engaging groove 51a with the engaging projection 26 formed on the supporting member 2 correspondingly.
Further, a plurality of engagement grooves 52a extending in the axial direction are formed in the metal ring 52 on the inner peripheral side, and the engagement protrusions 12d formed on the shaft portion 12a of the swing shaft 12 are correspondingly formed. By engaging the engagement groove 52a, the relative rotation of the both is regulated. Then, the metal ring 51 on the outer peripheral side
The metal ring 52 on the inner peripheral side of the support member 2 is the swing shaft 1
The two shaft portions 12a are fitted with a gap therebetween. In this embodiment, it is not necessary to press the urging member 3 into the shaft portion 12a of the swing arm 1 or the main body portion 21 of the support member 2, so that the assembly can be easily performed.

FIG. 6 is a sectional view showing still another embodiment. In this embodiment, the swing shaft 27 is provided on the support member 2 side.
And a cylindrical hub 17 is provided on the base 1b side of the swing arm 1, and between the swing shaft 27 and the hub 17 is parallel to the rotation center axis L, as in the above embodiment. The biasing member 3 is interposed with the shear stress F applied. On the base side of the support member 2, a flange portion 22 fixed to an engine or the like and a hub 17 of the swing arm 1 are provided.
Large-diameter portion 28 that rotatably fits through the bush 25
Are provided. Further, the tip end portion of the swing shaft 27 is fitted to the base portion 1b of the swing arm 1 via a bush 24, and the annular plate 6 is fixed to the tip end surface by bolting or the like. There is. The outer surface of the base portion 1b of the swing arm 1 is pressed against the annular plate 6 via the friction member 4.

Also in this embodiment, similarly to the above embodiment, the vibration energy of the belt can be stably absorbed and a desired tension can be stably applied to the belt. FIG. 7 is a cross-sectional view of an essential part showing still another embodiment. In this embodiment, in the auto tensioner shown in FIG. 1, instead of the disc-shaped flange portion 12c of the swing shaft 12, an annular member 12e made of sheet metal is formed separately from the swing shaft 12. The annular member 12e has a substantially U-shaped cross section, the outer periphery of which is press-fitted and fixed to the tubular portion 21 of the support member 2, and the inner periphery thereof is made of a resin such as nylon. The cylindrical shaft portion 12a of the swing shaft 12 is rotatably fitted through the bush 25a. Other configurations are similar to those shown in FIG.

In this embodiment, since it is not necessary to integrally form the large-diameter flange portion 12c on the swing shaft 12, the swing shaft 12 can be easily machined and the flange portion 12c can be easily machined. Since the annular member 12e made of sheet metal is used instead, the cost can be reduced.

The autotensioner of the present invention is not limited to the above embodiment, and for example, the biasing member 3 can be used.
Instead of being press-fitted into either one of the swing arm 1 and the support member 2, they are joined and integrated by baking or the like, and the friction member 4 is fixed to the swing arm 1 side.
It is possible to make various design changes such as pressing the support member 2 to the support member 2 via the friction member 4.

[0021]

As described above, according to the auto tensioner of the first aspect, the biasing member made of the elastomer is
The rocking arm is elastically deformed so that shear stress is generated in the direction along the rocking center axis, and the restoring action to this elastic deformation imparts a frictional force to the rocking arm. It is possible to prevent the friction damping characteristics from largely changing due to the axial accuracy and displacement of the support member. Therefore, the vibration energy of the belt can be effectively and stably absorbed, and a desired tension can be stably applied to the belt.

According to the auto tensioner of the second aspect, the metal rings fixed to the inner circumference and the outer circumference of the biasing member are
Since the urging member can be incorporated between the support member and the swing arm by simply inserting the bias member into the support member and the swing arm, a unique effect is obtained in that the assembly can be easily performed. .

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view of a main part showing an assembly process.

FIG. 4 is a main-portion cross-sectional view showing an assembling process.

FIG. 5 is an enlarged cross-sectional view showing another embodiment.

FIG. 6 is a sectional view showing still another embodiment.

FIG. 7 is a cross-sectional view of main parts showing still another embodiment.

FIG. 8 is a cross-sectional view showing a conventional auto tensioner.

[Explanation of symbols]

 1 Swing Arm 11 Pulley 2 Support Member 3 Energizing Member 4 Friction Member 51 Metal Ring 52 Metal Ring L Rotation Center Axis F Shear Stress

Claims (2)

[Claims] 1. A swing arm having a pulley attached to a tip thereof, a support member for swingably supporting the swing arm and movable along a swing center axis, and the swing arm and the support member. And a ring-shaped urging member made of an elastomer arranged coaxially with the swing center axis of the oscillating arm. The moving arm is brought into pressure contact with the support member via the friction member or the friction member to give the swinging arm a turning resistance, and the twisting resistance of the biasing member causes the swinging arm to turn in a predetermined direction. In an auto tensioner that urges, the urging member is elastically deformed so that shear stress is generated in a direction along the swing center axis of the swing arm, and is relatively moved around the swing center axis. With the rotation restricted, the support member An auto tensioner characterized by being fitted to each of the arms. 2. A metal ring is fixed to each of an inner circumference and an outer circumference of the urging member, and each metal ring is rocked with a support member in a state in which relative rotation around a rocking center axis is restricted. To the arm,
The autotensioner according to claim 1, wherein the autotensioners are fitted with a gap therebetween.