JP3820380B2 - 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 point, 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.
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]
[Problems to be solved by the invention]
In the conventional auto tensioner as described above, the swing arm that has received the belt tension fluctuation rapidly attenuates the swing by the swing resistance while swinging. However, in recent years, automobile engines (lean fuel engines, direct injection engines, etc.) whose rotational fluctuations are larger than those of conventional ones have appeared, and as a result, there is a tendency for the swing amount and tension fluctuation to increase. When a conventional auto tensioner is used for such an engine, the wear of the friction plate is accelerated more than before and the life is shortened.
[0004]
In view of the above-described conventional problems, an object of the present invention is to provide an auto tensioner that suppresses the progress of wear of a friction plate even when the belt tension fluctuation is large due to an engine with large rotation fluctuation.
[0005]
[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 swingably supports the swing arm, and a swing on the swing arm side. And a friction plate that provides a rocking resistance against the rocking of the rocking arm and twists and biases the rocking arm in a predetermined rocking direction. And a torsion coil spring for urging the swing arm in the swing central axis direction with respect to the support member so that the swing portion and the non-moving portion are pressed against each other across the friction plate; The swing arm is separate from the swing arm, and is attached to a base end outer cylindrical portion of the swing arm as a radially outward projection, and rotates about the swing center of the swing arm. A movable member and fixed on the outer periphery of the support member, and the movable member It is arranged on both sides of the rotation direction so as to sandwich the material, and in response to the swinging of the swinging arm in any direction, the movable member is received and elastic deformation is generated accordingly. And a rubber-like elastic body that restricts swinging within the limit of deformation (claim 1).
In the auto tensioner configured as described above, any one of the rubber-like elastic bodies arranged on both sides in the rotational direction of the movable member is pushed by the movable member due to the swing of the swing arm, causing elastic deformation, Oscillation is restricted within the limit of the elastic deformation. Therefore, even if the belt tension fluctuation is large due to the engine having a large fluctuation in rotation, it is possible to restrict the movement of the friction plate by suppressing the movement in any direction.
[0006]
Further, the rubber-like elastic body functions as a damper, consumes swinging energy of the swing arm with friction plates. Therefore, the swing can be attenuated more quickly.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are a cross-sectional view and a side view, respectively, of an auto tensioner according to an embodiment of the present invention. 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, a cylindrical portion 4c, and a proximal outer cylinder portion 4d are integrally formed with the distal end portion 4a by aluminum die casting.
[0008]
On the other hand, the support member 7 that supports the swing arm 4 includes 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. It is a molded member formed integrally by die casting. 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.
[0009]
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.
[0010]
On the other hand, the annular friction plate 10 is orthogonal to the oscillation center axis X and is interposed between the flange 4 b of the oscillation arm 4 and the annular pressing plate 11. The friction plate 10 is made of, for example, a clutch facing material. 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. 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.
[0011]
In FIG. 2, the mounting plate 12 is integrally provided on the outer periphery of the spring receiving portion 7 b (FIG. 1) of the support member 7, and a pair of rubber-like elastic bodies (urethane rubber or the like) 13 is attached to the mounting plate 12. It is fixed to. The rubber-like elastic body 13 is in contact with a wall surface 12a formed on the mounting plate 12, and cannot move in the contact direction. Further, the mounting plate 12 can be separated from the spring receiving portion 7b. On the other hand, a protrusion 14 as a movable member that rotates about the center of swinging of the swinging arm 4 is sandwiched between the pair of rubber-like elastic bodies 13 in the base end outer cylinder portion 4d of the swinging arm 4. Is attached. The projections 14, if example embodiment, are constructed separately in a kind of bolt to be screwed to the base end outer cylindrical portion 4d. The protrusion 14 rotates within a predetermined range corresponding to the swing range of the swing arm 4. The rubber-like elastic body 13 is a fixing member for the protrusion 14 as a movable member, and these constitute a stopper device 15 that restricts the swinging arm 4 from swinging within a predetermined range. Further, the rubber-like elastic body 13 provides the swinging arm 4 with a damper function that absorbs swinging energy by elastic deformation.
[0012]
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 pressing plate 11 as a “non-moving portion” with respect to the “swinging portion” is fixed. Accordingly, the relative rotation between the presser plate 11 and the flange portion 4b causes friction in the friction plate 10 in a state of being in pressure contact therebetween. As a result, a swing resistance (friction resistance) is applied to the swing arm 4.
[0013]
Further, the protrusion 14 is rotated by the swing of the swing arm 4 and is pressed against one of the pair of rubber-like elastic bodies 13. The rubber-like elastic body 13 that receives the protruding portion 14 is elastically deformed and allows the protruding portion 14 to rotate. However, when the swing amount increases, the compression limit is reached and the rotating of the protruding portion 14 is restricted. When the rotation of the protrusion 14 is restricted, the swing of the swing arm 4 is restricted. Thus, when the swinging amount becomes larger than the compression limit of the rubber-like elastic body 13, the swinging is restricted by the stopper device 15.
Therefore, even when the tension fluctuation of the belt 1 is large due to the engine having a large rotation fluctuation, the vibration can be restricted and the progress of wear of the friction plate 10 can be suppressed.
The rubber-like elastic body 13 functions as a damper by internally absorbing energy during elastic deformation and consumes the swing energy of the swing arm 4 together with the friction plate 10. Therefore, the swing can be attenuated more quickly than in the case of only the friction plate 10.
[0014]
In the stopper device 15 of the above embodiment, the rubber-like elastic body 13 is a fixed member on the support member 7 side, and the protrusion 14 is a movable member on the swing arm 4 side. The protrusion 14 may be provided on the side, and the rubber-like elastic body 13 may be provided on the swing arm 4 side. It is also possible to use rubber-like elastic bodies for both the fixed member and the movable member.
Various springs can be used in place of the rubber-like elastic body 13, but the rubber-like elastic body is generally preferable for internal absorption of energy during elastic deformation. Further, if a low-rebound rubber having a very small rebound resilience is adopted, the damping effect of the rocking energy can be further enhanced.
[0015]
【The invention's effect】
The present invention configured as described above has the following effects.
According to the auto tensioner of the first aspect, any one of the rubber-like elastic bodies arranged on both sides in the rotational direction of the movable member is pushed by the movable member by the swinging of the swinging arm to cause elastic deformation, Since the oscillation is restricted within the limit of elastic deformation, even if the belt tension fluctuation is large due to the engine with large rotational fluctuation, the oscillation is restricted against any fluctuation in any direction, and the friction plate is worn. Progress can be suppressed.
[0016]
Further , since the rubber-like elastic body functions as a damper and consumes the swing energy of the swing arm together with the friction plate, the swing can be attenuated more quickly.
[Brief description of the drawings]
FIG. 1 is a 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.
[Explanation of symbols]
1 Belt 2 Pulley 4 Oscillating arm 4b Hook (Oscillating part)
4c Cylindrical portion 7 Support member 9 Torsion coil spring 10 Friction plate 11 Holding plate (non-moving portion)
12 Mounting plate 13 Rubber elastic body (fixing member)
14 Protrusion (movable member)
15 Stopper device X Swing center shaft

Claims (1)

A swing arm that rotatably supports a pulley around which a belt is wound at a tip portion;
A support member for swingably supporting the swing arm;
A friction plate interposed between the swinging part on the swinging arm side and the non-moving part on the support member side and imparting a swinging resistance to the swinging of the swinging arm;
The swing arm is twisted and biased in a predetermined swing direction, and the swing arm is moved against the support member so that the swing portion and the non-moving portion are pressed against each other with the friction plate interposed therebetween. A torsion coil spring biased in the direction of the swing center axis;
The swing arm is separate from the swing arm, and is attached to a base end outer cylindrical portion of the swing arm as a radially outward projection, and rotates about the swing center of the swing arm. A movable member;
It is fixed on the outer periphery of the support member, and is arranged on both sides of the rotation direction so as to sandwich the movable member, so that the swing arm can swing in any direction accordingly. An auto-tensioner comprising: a rubber-like elastic body that receives the movable member to cause elastic deformation and restricts swinging within a limit of the elastic deformation.

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