JPH0567854U - Auto tensioner - Google Patents

Abstract

(57) [Summary] [Structure] A snap ring 70 for urging the friction member 60 toward the inner peripheral surface 21 side of the fixed case 20 is tightly attached to the inner peripheral surface of the friction member 60, and the friction member 60 is swingable. The outer peripheral surface of the boss 31 is integrally rotatably fitted. Friction member 60
Is fixed outside the torsion coil spring 40 in the radial direction.
The inner peripheral surface 21 of 0 is slidably contacted. [Effect] When the swing arm is rotated, a frictional force is generated between the friction member and the fixed case, and swing resistance can be imparted to the swing arm. It is possible to secure a large distance between the position where the frictional force acts and the pivot axis of the swing arm, and to obtain a large swing resistance.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an auto tensioner for maintaining a constant tension of a belt or the like wound around a pulley.

[0002]

[Prior Art]

 Generally, an auto tensioner is used to adjust the tension of a belt wound between a plurality of auxiliary machines such as an alternator, a cooler pump and a power steering ring pump of an automobile. The auto-tensioner has a swing arm with a pulley attached at its tip, which is pivotally attached to the base so that the swing arm can be pressed by a torsion coil spring that is approximately concentric with the center of rotation. The swinging range of the swinging arm is set so that it can follow the tension of the belt due to the expansion and contraction of the belt.

By the way, in the case of a four-cylinder engine, for example, the number of revolutions of the crankshaft of the engine normally fluctuates twice per revolution. This rotation fluctuation becomes considerably large, especially when the engine load is large. Therefore, the fluctuation of the belt tension also becomes large, and the swing arm of the auto tensioner vibrates violently. This vibration not only lowers the durability of the auto tensioner itself, but also shortens the life of the belt and causes an uncomfortable state such as squealing of the belt due to belt slippage.

Therefore, the conventional autotensioner has a mechanism (damper mechanism) that gives a predetermined swing resistance to the swing arm so that the swing arm does not easily swing due to the vibration of the belt. Has been adopted. As a damper mechanism that gives a swing resistance to the swing arm, the applicant of the present invention forms a cylindrical boss 1a at the center of rotation of the swing arm as shown in FIG. The pin A is rotatably attached to the fixed casing 4 having a bottom, and the compression coil springs 2 and the friction members 3 are respectively attached to the swing arm 1 at a plurality of positions around the boss 1a. It has been proposed to provide rocking resistance by arranging in parallel with the axis line and pressing the friction member 3 against the fixed case 4 or the rocking arm 1 by the urging force of each compression coil spring 2 (Japanese Patent Laid-Open No. HEI 2). -168049 gazette). Reference numeral 5 in the drawing denotes a torsion coil spring that urges the swing arm 1 in one swing direction and presses it against the pulley 6.

[0005]

[Problems to be solved by the device]

 However, the autotensioner proposed in Japanese Patent Application Laid-Open No. 2-168049 uses a plurality of compression coil springs 2 in addition to the torsion coil spring 5 in order to impart swing resistance as shown in FIG. Since the friction member 3 is pressed against the fixed case 4 or the swing arm 1 by the biasing force of each compression coil spring 2, the number of parts is increased and the cost is increased. Moreover, the assembling work is also complicated.

Further, in the above auto tensioner, since the friction surface between the friction member 3 and the fixed case 4 or the swing arm 1 is located inside the torsion coil spring 5 in the radial direction, There is a problem that a sufficient swing resistance cannot be secured because the distance between the rotation axis and the friction surface is short. In view of the above, the present invention provides a swinging resistance to the swinging arm without using compression coil springs at a plurality of positions around the swinging axis of the swinging arm, thereby reducing the cost by reducing the number of parts. Another object of the present invention is to provide an auto tensioner that can simplify assembly work and increase swing resistance.

[0007]

[Means for Solving the Problems]

 A means for solving the problems according to the present invention has a pulley attached to the front end, and an annular boss concentric with a bottomed cylindrical fixed case on the base end side. It is equipped with a swing arm that is movably attached to it, and a torsion coil spring that is installed inside the fixed case and that is installed approximately concentrically with the swing axis of the swing arm. In an auto tensioner that is urged to rotate, from an elastic material that is fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case, and is in radial contact with the other side of the torsion coil spring in the radial direction. And an annular urging member for pressing and urging the friction member in the state of being fitted to the friction member.

[0008]

[Action]

 In the above problem solving means, since the friction member fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case is pressed and biased to the other side by the biasing force of the biasing member, the swing arm is When rotated, a frictional force is generated between the friction member fixed to the one side and the other side, and swing resistance can be imparted to the swing arm.

Since the friction member for generating the frictional force is slidably contacted with the other side on the outer side in the radial direction of the torsion coil spring, the position where the frictional force acts is the radial direction of the torsion coil spring as in the conventional case. As compared with the case of being inward, it is possible to secure a large distance from the pivot axis of the rocking arm for the position where the frictional force acts, and it is possible to obtain a large rocking resistance.

[0010]

【Example】

 Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a vertical sectional side view of an auto tensioner according to a first embodiment of the present invention, and FIG. 2 is a transverse plan view showing a mounting state of a boss of a swing arm and a friction member. As shown in FIG. 1, the auto tensioner of this embodiment has a swing arm 30 having a belt-wound pulley 10 attached to the tip thereof and an annular boss 31 serving as a rotation center on the base end side. An annular friction member 60 that is integrally rotatably mounted on the outer peripheral surface of the boss 31 of the swing arm 30, and a bottomed cylindrical fixed case 20 that rotatably supports the boss 31 via the friction member 60. And a torsion coil spring 40 which is installed in the fixed case 20 and biases the swing arm 30 to rotate in a predetermined direction, and keeps the tension of a belt (not shown) wound around the pulley 10 constant. Is.

A shaft 50 is projectingly provided at the turning tip of the swing arm 30, and the pulley 10 is rotatably supported by the shaft 50 via a bearing 51. Further, a hub 32 is provided on the base end side of the swing arm 30, and the boss 31 is provided on the periphery of the hub 32 at a radially outer position of the spiral torsion coil spring 40. Has been done. A through hole 32a penetrating in the axial direction is formed in the center of the hub 32, and 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 into the fixed case 20, and the swing arm 30 is axially movably fixed to the fixed case 20 by the support shaft 53. At the same time, it is prevented from coming off the fixed case 20. The through hole 32a is set to be larger than the diameter of the threaded portion of the support shaft 53 by a predetermined dimension. A counterbore 32b is recessed in the upper portion of the hub 32, and a thrust washer 54 is interposed between the bottom of the counterbore 32b and the head of the support shaft 53. Further, the outer peripheral surface and the inner peripheral surface of the boss 31 are formed on circumferential surfaces concentric with the rotation axis of the swing arm 30.

The friction member 60 is made of an elastic material such as resin or rubber. As shown in FIG. 2, on the inner circumference of the friction member 60, projections 61 for fitting in the grooves 34 formed at predetermined intervals on the outer circumference of the boss 31 extend in the axial direction at predetermined intervals in the circumferential direction. It is formed by being blown out. The relative rotation of the friction member 60 with respect to the boss 31 is restricted by the fitting between the protrusion 61 and the groove 34. Further, as shown in FIG. 1, the inner peripheral surface of the friction member 60 below the boss 31 has a C shape as a urging member for pressing and urging the friction member 60 toward the inner peripheral surface 21 side of the fixed case 20. One snap ring 70 is attached in a radially contracted state. The biasing force is appropriately set according to the required swing resistance.

The fixed case 20 is bolted to a predetermined portion (not shown), and is used to insert a fixing bolt into a flange portion 22 provided at the bottom of the case 20. A through hole 23 is formed. A receiving portion 21a for slidably fitting and supporting the outer peripheral surface of the friction member 60, which is integrally rotatably fitted to the outer peripheral surface of the boss 31, is provided in the upper portion of the inner peripheral surface 21 of the fixed case 20. Has been done. The receiving portion 21a is in sliding contact with the outer peripheral surface of the friction member 60 to generate a frictional force between the friction member 60 and the friction member 60, and imparts rocking resistance to the rocking arm 30. It is formed on a circumferential surface concentric with the rotation axis of 30. A gap of a predetermined size is provided between the upper end of the receiving portion 21a and the base end of the swing arm 30. Further, an arcuate notch groove 25b is formed in a part of the outer peripheral surface 25 of the fixed case 20 along the rotation direction of the swing arm 30. A stopper 55 protruding from the swing arm 30 is inserted into the notch groove 25b, and the stopper 55 abuts the wall surface of the notch groove 25b when the swing arm 30 is rotated, so that the swing arm 30 is rotated. Unnecessary rotation is restricted.

In the above structure, the friction member 60 fitted to the outer peripheral surface of the boss 31 of the swing arm 30 so as to be integrally rotatable is urged by the snap ring 70 toward the inner peripheral surface 21 side of the fixed case 20. Therefore, when the swing arm 30 rotates about the boss 31, the urging force causes the friction member 60 to rotate while being pressed against the receiving portion 21a 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 a swinging resistance due to this frictional force is imparted to the swinging arm 30. As a result, the swinging arm 30 is resonated. It can prevent violent vibration.

As described above, in the above embodiment, as the damper mechanism that gives the swinging resistance to the swinging arm 30, compression coils are provided at a plurality of positions around the rotation axis of the swinging arm as in the conventional case. Since no springs are required, not only is the cost reduced by reducing the number of parts, but also the assembly work is 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 of the torsion coil spring 40, the friction force generated by the friction member 60 is as in the conventional case. Compared with the case where the acting position of the frictional force is inward of the torsion coil spring in the radial direction, the frictional force acts at a position far away from the rotation axis of the swing arm 30. As a result, a large swing resistance can be obtained. it can.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a vertical sectional side view of an automatic tensioner according to a second embodiment of the present invention, and FIG. 4 is a transverse 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 mainly differs from the first embodiment of FIG. 1 in that the friction member 60 is fixed to the fixed case 20 side and slidably contacted to the swing arm 30 side. Is the point.

That is, the friction member 60 is fixed to the receiving portion 25 a provided in the outer peripheral surface 25 of the fixed case 20, and the boss 31 of the swing arm 30 is relatively rotatable on the outer periphery of the friction member 60. Has been inserted into. As shown in FIG. 4, projections 61 extending in the axial direction are formed on the inner peripheral surface of the lower end portion of the friction member 60 at predetermined intervals in the circumferential direction. The projections 61 are provided on the outer periphery of the receiving portion 25a of the fixed case 20. The friction member 60 is non-rotatably attached to the receiving portion 25a by fitting into the grooves 27 formed at predetermined intervals. A snap ring 70, which presses and urges 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 radially expanded state. Further, an arcuate notch groove 63 is formed along the rotation direction of the swing arm 30 on a part of the outer peripheral surface of the friction member 60 above the mounting portion of the snap ring 70. A stopper 55 protruding from the swing arm 30 is inserted into the notch groove 63, and the stopper 55 comes into contact with the wall surface of the notch groove 63 when the swing arm 30 is rotated, so that the swing arm 30 is rotated. The unnecessary rotation of 30 is restricted.

As shown in FIG. 3, the outer peripheral surface 21 and the receiving portion 25a of the fixed case 20 are formed on a circumferential surface concentric with the center of rotation of the swing arm 30. Other configurations are similar to those of the first embodiment. In the above structure, 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. Therefore, when the swing arm 30 rotates, the boss 31 rotates while receiving the pressing force of the friction member 60. Therefore, a frictional force is generated between the boss 31 and the friction member 60, and swing resistance can be imparted to the swing arm 30. Therefore, as in the first embodiment, not only the cost is reduced by reducing the number of parts, but also the assembling work is simplified.

Further, since the boss 31 is brought into sliding contact with the friction member 60 radially outward of the torsion coil spring 40, the distance between the operating position of the rotation axis of the swing arm 30 and the friction surface is increased. Therefore, a large swing resistance can be obtained. The present invention is not limited to the above embodiment, and many modifications and changes can be made within the scope of the present invention.

In the above-described embodiment, the friction member 60 is provided with a slit at the portion on which the snap ring 70 acts so that the friction member 60 can easily expand or contract in diameter. It may be possible to reduce the force exerted to obtain greater swing resistance. Further, only the sliding surface (friction surface) of the friction member 60 may be made of resin or rubber, and the other portions may be made of metal.

[0021]

[Effect of the device]

 As is apparent from the above description, according to the present invention, the friction member fixed to either the peripheral surface of the boss or the peripheral surface of the fixed case is urged to the other side by the urging force of the urging member. Therefore, when the swing arm is rotated, a frictional force is generated between the friction member and the other side, and swing resistance can be imparted to the swing arm.

Therefore, it is not necessary to use compression coil springs at a plurality of positions as the damper mechanism, and not only the cost can be reduced by reducing the number of parts but also the assembling work can be simplified. Since the friction member that generates the frictional force is slidably contacted with the other side outside the torsion coil spring in the radial direction, the position where the frictional force acts is inward in the radial direction of the torsion coil spring as in the conventional case. Compared with the case, it is possible to secure a large distance between the acting position of the frictional force and the pivot axis of the swing arm, and it is possible to obtain a large swing resistance.

[Brief description of drawings]

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

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

FIG. 3 is a vertical sectional side view of an automatic tensioner according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional plan view showing a mounted 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]

 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)

[Scope of utility model registration request] 1. A pulley is attached to the tip, and an annular boss concentric with a bottomed cylindrical fixed case is provided on the base end side, and is rotatable with respect to the fixed case around the axis of the boss. Equipped with an attached swing arm and a torsion coil spring that is installed in the fixed case and is provided substantially concentric with the rotation axis of the swing arm. The twist coil spring biases the swing arm in a predetermined direction. In the automatic tensioner, an annular friction member made of an elastic material is fixed to one of the peripheral surface of the boss and the peripheral surface of the fixed case, and is in radial contact with the other side of the torsion coil spring, and is in sliding contact with the other. And an annular urging member for pressing and urging the friction member toward the other side when fitted to the friction member.