JP2568015Y2 - Auto tensioner - Google Patents

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 maintaining a constant tension of a belt or the like wound around a pulley.

[0002]

2. Description of the Related Art Generally, an automatic tensioner is used to adjust the tension of a belt wound around a plurality of accessories such as an alternator, a cooler pump and a power steering pump of an automobile. The auto tensioner has a swing arm with a pulley attached to the tip, which is pivotally fixed to the base, and the swing arm is
A torsion coil spring provided substantially concentrically with the center of rotation is urged to rotate in the direction in which the belt is pressed, and swings so that it can follow the belt tension caused by the expansion and contraction of the belt. Swing range is set.

The number of revolutions of the crankshaft of an engine, for example, in the case of a four-cylinder engine, usually fluctuates twice per revolution. This rotation fluctuation becomes considerably large especially when the load of the engine is large. For this reason, the fluctuation of the belt tension also increases, and the swing arm of the auto tensioner vibrates violently. This vibration not only reduces the durability of the auto-tensioner itself, but also shortens the life of the belt and causes an unpleasant state such as belt squeal due to the slip of the belt.

Therefore, a conventional auto tensioner employs a mechanism (damper mechanism) for giving a predetermined swing resistance to the swing arm so that the swing arm does not easily swing due to the vibration of the belt. ing. As a damper mechanism for giving a swing resistance to the swing arm, as shown in FIG. 5, the present applicant forms a cylindrical boss 1a at the center of rotation of the swing arm, and attaches this boss 1a. It is rotatably attached to the bottomed cylindrical fixed case 4 with the pin A, and the compression coil spring 2 and the friction member 3 are respectively parallel to the rotation axis of the swing arm 1 at a plurality of locations around the boss 1a. Are arranged in such a manner that the frictional member 3 is pressed against the fixed case 4 or the swing arm 1 by the urging force of each compression coil spring 2 to impart swing resistance (Japanese Patent Laid-Open No. Hei 2 (1994)).
-168049). In the figure, reference numeral 5 denotes a torsion coil spring that urges the swing arm 1 in one swing direction and presses the swing arm 1 against the pulley 6.

[0005]

However, the auto-tensioner proposed in Japanese Patent Application Laid-Open No. 2-168049 has a plurality of torsional coil springs 5 as shown in FIG. Since the compression coil springs 2 are used and the friction members 3 are pressed against the fixed case 4 or the swing arm 1 by the urging force of each compression coil spring 2, the number of parts is increased and the cost is increased. Also, the assembling work has been complicated.

[0006] Further, in the above-mentioned auto tensioner,
Since the friction surface between the friction member 3 and the fixed case 4 or the swing arm 1 is located radially inward of the torsion coil spring 5, the distance between the rotation axis of the swing arm 1 and the friction surface is reduced. There was a problem that it was short and sufficient swing resistance could not be secured. In view of the above, the present invention provides swing resistance to the swing arm without using compression coil springs at a plurality of locations around the rotation axis of the swing arm, thereby reducing the number of parts and reducing the cost and assembly. It is an object of the present invention to provide an auto tensioner that can simplify the operation and increase the swing resistance.

[0007]

Means for Solving the Problems According to the present invention, a pulley is attached to a distal end, and an annular boss concentric with a bottomed cylindrical fixed case is provided on a base end side. A swing arm mounted rotatably about the axis of the boss, and a torsion coil spring provided inside the fixed case and provided substantially concentrically with the rotation axis of the swing arm. In the auto-tensioner, which urges the swing arm to rotate in a predetermined direction, the auto-tensioner is fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case. An annular friction member made of an elastic material that is slidably contacted, and an annular urging member that presses and urges the friction member toward the other side when fitted to the friction member. .

[0008]

In the above means for solving the above problems, the friction member fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case is urged to the other side by the urging force of the urging member. When the moving arm is rotated, a frictional force is generated between the friction member fixed to the one side and the other side, and a swing resistance can be given to the swing arm.

Since the frictional member for generating the frictional force is slidably contacted with the other side on the outside in the radial direction of the torsion coil spring, the operation position of the frictional force is set in the radial direction of the torsion coil spring as in the related art. In this case, the distance between the operating position of the frictional force and the pivot axis of the swing arm can be ensured to be larger than in the case where the frictional force is present, and a large swing resistance can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional side view of the auto tensioner according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional plan view showing a mounted state of a boss of a swing arm and a friction member. As shown in FIG. 1, the auto-tensioner according to the present embodiment includes a swing arm 30 having a belt wrapping pulley 10 attached to a distal end thereof and an annular boss 31 serving as a rotation center at a base end side. An annular friction member 60 is attached to the outer peripheral surface of the boss 31 so as to be integrally rotatable.
A fixed case 20 having a bottomed cylindrical shape that rotatably supports 1
A torsion coil spring 40 is provided inside the fixed case 20 and urges the swing arm 30 to rotate in a predetermined direction. The torsion coil spring 40 keeps the tension of a belt (not shown) wound around the pulley 10 constant. .

A shaft 50 protrudes from the pivoting end of the swing arm 30, and the pulley 10 is rotatably supported on the shaft 50 via a bearing 51. A hub 32 protrudes from the base end side of the swing arm 30. Around the hub 32, a torsion coil spring 40 is provided.
The boss 31 is protruded at a radially outward position of the boss 31. A through hole 32a is formed in the center of the hub 32 so as to penetrate in the axial direction. The support shaft 53 of the swing arm 30 is inserted into the through hole 32a. The tip screw portion of the support shaft 53 is screwed to the fixed case 20, and the support shaft 5
3, the swing arm 30 is axially movable with respect to the fixed case 20 so as to be freely movable in the axial direction, and is prevented from falling out of the fixed case 20. The through hole 32
a is set to be larger by a predetermined dimension than the diameter of the threaded portion of the support shaft 53. A counterbore 32b is provided on the upper part of the hub 32.
Are recessed, and the bottom of the counterbore 32b and the support shaft 53 are provided.
A thrust washer 54 is interposed between the head and the head. The outer peripheral surface and the inner peripheral surface of the boss 31 are formed on a circumferential surface concentric with the rotation axis of the swing arm 30.

The friction member 60 is made of an elastic material such as resin and rubber. On the inner periphery of the friction member 60, as shown in FIG. 2, projections 61 for fitting into the grooves 34 formed at predetermined intervals on the outer periphery of the boss 31 extend in the axial direction at predetermined intervals in the circumferential direction. It has been formed. The fitting of the protrusion 61 and the groove 34 restricts the relative rotation of the friction member 60 with respect to the boss 31. As shown in FIG. 1, a C-shaped urging member for urging the friction member 60 toward the inner peripheral surface 21 of the fixed case 20 is provided on the inner peripheral surface of the friction member 60 below the boss 31. Are mounted in a state of being contracted in the radial direction. The biasing force is appropriately set according to the required swing resistance.

The fixed case 20 is provided at a predetermined position (not shown).
And a through-hole 23 for inserting a fixing bolt is formed in a flange portion 22 provided at the bottom of the case 20. A receiving portion 21a that slidably fits and supports the outer peripheral surface of the friction member 60 that is integrally rotatably fitted to the outer peripheral surface of the boss 31 is provided above the inner peripheral surface 21 of the fixed case 20. Have been. The receiving portion 21 a slides on the outer peripheral surface of the friction member 60 to generate a frictional force with the friction member 60, and provides a swing resistance to the swing arm 30. 30 is formed on a circumferential surface concentric with the rotation axis. Note that a gap having a predetermined size is provided between the upper end of the receiving portion 21a and the base end of the swing arm 30. Also,
A part of the outer peripheral surface 25 of the fixed case 20 includes a swing arm 3
An arc-shaped notch groove 25b is formed along the 0 rotation direction. A stopper 55 projecting from the swing arm 30 is inserted into the notch groove 25b.
The stopper 55 contacts the wall surface of the notch groove 25b during the rotation of the swing arm 30, thereby restricting the swing arm 30 from rotating more than necessary.

In the above configuration, the friction member 60 fitted integrally rotatably to the outer peripheral surface of the boss 31 of the swing arm 30.
Is urged toward the inner peripheral surface 21 of the fixed case 20 by the snap ring 70, so that when the swing arm 30 rotates around the boss 31, the urging force causes the friction member 6 to move.
0 rotates while being pressed against the receiving portion 21 a of the fixed case 20. As a result, a frictional force is generated between the receiving portion 21a of the fixed case 21 and the friction member 60, and the swinging resistance due to the frictional force is applied to the swinging arm 30, so that the swinging arm 30 is caused by resonance or the like. Vibration can be prevented.

As described above, in the above-described embodiment, the compression coil springs are provided at a plurality of positions around the rotation axis of the swing arm as a conventional damper mechanism for giving the swing resistance to the swing arm 30. Since it does not need to be used, not only the cost can be reduced by reducing the number of parts but also the assembling work can be simplified. Further, since the friction member 60 is slidably contacted with the receiving portion 21a of the fixed case 20, which is located radially outward from the torsion coil spring 40, the friction force by the friction member 60 is different from that of the related art. As a result of acting at a position far from the rotation axis of the swing arm 30 as compared with the case where the force acts at a position radially inward of the torsion coil spring, a large swing resistance can be obtained.

[0016] Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a longitudinal sectional side view of the auto-tensioner according to the second embodiment of the present invention, and FIG. 4 is a cross-sectional plan view showing a mounting state of an outer peripheral surface of a fixed case and a friction member. Referring to FIG. 3, the present embodiment is different from the first embodiment of FIG. 1 mainly in that friction member 60 is fixed to fixed case 20 side and slidably contacts swing arm 30 side. It is a point.

That is, the friction member 60 is fixed to the fixed case 2.
The boss 31 of the swing arm 30 is fixed to a receiving portion 25 a recessed on the outer peripheral surface 25 of the swing arm 30.
Inserted so as to be able to rotate relatively. As shown in FIG. 4, projections 61 extending in the axial direction are formed at predetermined intervals in the circumferential direction on the inner peripheral surface of the lower end portion of the friction member 60.
Is fitted into grooves 27 formed at predetermined intervals on the outer periphery of the receiving portion 25a of the fixed case 20, whereby the friction member 60 is non-rotatably attached to the receiving portion 25a. A snap ring 70 that presses and biases the friction member 60 toward the outer peripheral surface of the boss 31 is attached to the outer peripheral surface of the friction member 60 in a state where the snap ring 70 is radially expanded. Further, an arc-shaped notch groove 63 is formed in a part of the outer peripheral surface of the friction member 60 above the mounting portion of the snap ring 70 along the rotation direction of the swing arm 30. A stopper 55 projecting from the swing arm 30 is inserted into the notch groove 63, and the stopper 55 contacts the wall surface of the notch groove 63 when the swing arm 30 rotates, whereby the swing arm 30 is rotated. Is restricted from rotating more than necessary.

Outer peripheral surface 21 of fixed case 20 and receiving portion 2
5a is formed on a circumferential surface concentric with the center of rotation of the swing arm 30, as shown in FIG. Other configurations are the same as in the first embodiment. In the above configuration, since the friction member 60 fixed to the receiving portion 25a of the fixed case 20 is urged toward the outer peripheral surface side of the boss 31 by the snap ring 70,
When the swing arm 30 rotates, the boss 31 moves to the friction member 60.
It rotates while receiving the pressing force. Therefore, a frictional force is generated between the boss 31 and the friction member 60, and the swing arm 30
Swing resistance can be given to Therefore, as in the first embodiment, not only the cost can be reduced by reducing the number of parts, but also the assembling work can be simplified.

The boss 31 is provided with a torsion coil spring 40.
The frictional member 60 slides radially outward, so that the distance between the rotation axis of the swing arm 30 and the friction surface can be increased, and a large swing resistance can be obtained.
The present invention is not limited to the above embodiment,
Of course, many modifications and changes may be made within the scope of the present invention.

In the above embodiment, a slit is provided in the portion of the friction member 60 where the snap ring 70 acts, so that the friction member 60 can easily expand or contract in diameter. Power down,
It may be obtained a larger swing resistance. Further, only the sliding surface (friction surface) of the friction member 60 may be made of resin or rubber, and the other parts may be made of metal.

[0021]

As is clear from the above description, according to the present invention, the friction member fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case is moved to the other side by the urging force of the urging member. When the swing arm is rotated because of being pressed and urged, a frictional force is generated between the friction member and the other side, and swing resistance can be imparted to the swing arm.

Accordingly, it is not necessary to use a compression coil spring at a plurality of locations as a damper mechanism, and the number of parts can be reduced to reduce the cost and simplify the assembling work. Since the friction member for generating the frictional force is slidably contacted with the other side on the radially outer side of the torsion coil spring, when the acting position of the frictional force is on the radially inner side of the torsion coil spring as in the related art. As compared with the above, a large distance between the position where the frictional force acts and the rotation axis of the swing arm can be ensured, and a large swing resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of an automatic tensioner according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional plan view showing a mounting state of a boss of a swing arm and a friction member.

FIG. 3 is a longitudinal sectional side view of the auto-tensioner according to the second embodiment of the present invention.

FIG. 4 is a cross-sectional plan view showing a mounting state of an outer peripheral surface of a fixed case and a friction member.

FIG. 5 is a vertical sectional side view of a conventional auto tensioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pulley 20 Fixed case 21 Inner peripheral surface 25 Outer peripheral surface 30 Swing arm 31 Boss 40 Torsion coil spring 60 Friction member 70 Snap ring

Claims (1)

(57) [Scope of request for utility model registration] A pulley is attached to a distal end, and an annular boss concentric with a bottomed cylindrical fixed case is provided on a base end side, and is rotatable about the axis of the boss with respect to the fixed case. An attached swing arm and a torsion coil spring provided in the fixed case and provided substantially concentrically with the rotation axis of the swing arm. The torsion coil spring biases the swing arm in a predetermined direction. An annular friction member made of an elastic material, which is fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case, and is slidably contacted with the other outside in the radial direction of the torsion coil spring. And an annular biasing member that presses and biases the friction member toward the other side when fitted to the friction member.