JP2014005870A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auto tensioner of asymmetric damping characteristics in which a friction member pressed against an inner circumferential surface of an inside cylindrical part is prevented from being worn partially.SOLUTION: A coil spring support part 11 is provided which integrates a leaf spring 5 to an inner diameter side of a first cylindrical part 1a as an inside cylindrical part by reducing a diameter of the leaf spring 5 and abuts a coil spring 4 which is deformed by expanding the diameter thereof to a rotation member 3 at a side where a folded part 5a of the leaf spring 5 is held with an end face 4a of the coil spring 4, at an inner circumferential side of the leaf spring 5 extending in an arcuate shape. Therefore, a friction member 6 is pressed against the inner circumferential surface of the first cylindrical part 1a by an elastic recovery force of the leaf spring 5 which is integrated by reducing the diameter, and the friction member 6 is prevented from being worn partially, by preventing the coil spring 4 which is deformed by expanding the diameter, from being abutted to the extending leaf spring 5, and by preventing the friction member 6 coupled to the leaf spring 5 from being pressed with pressure that is non-unfirm in the circumferential direction.

Description

  The present invention relates to an auto tensioner that adjusts the tension of a transmission belt.

  In an auto tensioner for adjusting the tension of a transmission belt in an auxiliary drive system of an automobile, etc., a fixing member provided with a first cylindrical portion and at least a portion overlap with the first cylindrical portion on the inside and outside in the radial direction and are arranged coaxially. A rotating member that is rotatably supported with respect to a fixed member and can be attached with a pulley on which a belt is wound, and an inner diameter side of two cylindrical portions that overlap radially inside and outside A coil spring that has one end locked to the fixed member and the other end locked to the rotating member, and biases the rotating member in one direction relative to the fixed member; The bent portion formed at one end is sandwiched between one of the fixing member and the rotating member and the end face of the coil spring, and the other end is provided as a free end, and is provided on the other fixing member or rotating member. Inner circle that overlaps inside and outside in the radial direction There is an elastic body that extends in an arc shape along the inner peripheral surface of the coil spring on the outer peripheral side of the coil spring, and a friction member that is coupled to the elastic body and contacts the inner peripheral surface of the inner cylindrical portion (For example, refer to Patent Documents 1-3). The elastic body is formed of a metal such as a leaf spring, and the friction member is formed of a synthetic resin whose main component is nylon resin or the like.

  This type of auto-tensioner has a friction member and an inner peripheral portion of the inner cylindrical portion when the rotating member rotates in the belt slack direction that lowers the belt tension and when it rotates in the belt tension direction that increases the belt tension. The frictional force generated between the rotating member and the surface can be made different so as to have an asymmetric damping characteristic with respect to the rotating direction of the rotating member. That is, by increasing the frictional force in the belt slack direction and increasing the damping, string vibration due to a sudden drop in the tension of the transmission belt can be prevented, and in the belt tension direction, the frictional force is reduced and the damping is weakened. As a result, the reduced tension of the transmission belt can be quickly recovered.

  Patent Documents 1 and 2 describe that the friction member coupled to the elastic body is pressed against the inner peripheral surface of the inner cylindrical portion by the outward spring force when the coil spring expands and deforms. Yes. Further, the device described in Patent Document 3 presses the friction member coupled to the elastic body against the inner peripheral surface (bottom wall portion) of the inner cylindrical portion by the spring force when the coil spring extends in the axial direction. A function is added.

JP 2006-97889 A Special table 2009-533619 JP 2010-112549 A

  In the auto tensioner having the asymmetric damping characteristic described in Patent Documents 1 and 2, the outward spring force of the coil spring when expanding in diameter tends to be uneven in the circumferential direction, and the uneven spring force in the circumferential direction causes There is a problem that the friction member pressed against the inner peripheral surface of the inner cylindrical portion is unevenly worn. When such uneven wear proceeds, the friction member may be detached from the elastic body.

  In FIG. 4 of Patent Document 2, the outer sleeve 16 (first cylindrical portion) of the base member 2 (fixing member) serving as the inner cylindrical portion extends radially inward along the circumferential portion to expand the diameter. A supporting projection 36 for supporting the spring element 11 (coil spring) is provided. As shown in FIG. 1, the supporting projection 36 is a support bush 21 (elastic body) of the friction lining 22 (friction member). Is provided in an axial region where the portion does not extend. For this reason, as shown in FIG. 2, the spring element 11 whose diameter is increased and deformed is brought into contact with the support bush 21, and the friction lining 22 is formed on the inner peripheral surface of the outer sleeve 16 with a non-uniform coil spring in the circumferential direction. It is pressed by the spring force.

  Thus, an object of the present invention is to provide an auto tensioner having an asymmetric damping characteristic in which a friction member pressed against an inner peripheral surface of an inner cylindrical portion does not wear unevenly.

  In order to solve the above-described problems, the present invention provides a fixing member provided with a first cylindrical portion, and a second cylindrical portion that is arranged coaxially with at least a portion overlapping with the first cylindrical portion inside and outside in the radial direction. A rotating member that is rotatably supported with respect to the fixed member and is capable of attaching a pulley around which a belt is wound, and is accommodated on the inner diameter side of the two cylindrical portions that overlap the inside and outside in the radial direction, One end is locked to the fixing member, the other end is locked to the rotating member, and a coil spring that rotates the biasing member in one direction with respect to the fixing member, and one end is fixed to the fixing member. Sandwiched between one of the member, one of the rotating members and the end face of the coil spring, the other end is a free end, provided on the other of the fixed member and the rotating member, The outer periphery of the coil spring along the inner peripheral surface of the inner cylindrical portion that overlaps the inner side In an auto tensioner comprising: an elastic body extending in a circular arc shape; and a friction member coupled to the elastic body and in contact with an inner peripheral surface of the inner cylindrical portion, the elastic body is elastically restored by the inner cylinder. A configuration in which a coil spring support portion is provided in pressure contact with the inner peripheral surface of the portion, and the one of the fixing member and the rotating member abuts on the inner peripheral side of the elastic body with the coil spring that undergoes diameter expansion deformation It was adopted.

  That is, the elastic body is pressed against the inner peripheral surface of the inner cylindrical portion by an elastic restoring force, and extends in an arc shape to the fixed member or the rotating member on the side that sandwiches one end of the elastic body with the end surface of the coil spring By providing a coil spring support portion that abuts the coil spring that expands and deforms on the inner circumference side of the elastic body, the elastic restoring force of the elastic body that is incorporated with a reduced diameter provides a uniform pressing force in the circumferential direction. The friction member is pressed against the inner peripheral surface of the inner cylindrical portion, and the coil spring that expands in diameter is brought into contact with the coil spring support portion and is not brought into contact with the extending elastic body, but is coupled to the elastic body. The friction member was not pressed, so that the friction member was not unevenly worn. The coil spring support portion also functions to suppress the inclination of the coil spring that urges the rotation member from rotating around the coil center.

  Preferably, the coil spring support portion has a circumferential position in a range of 80 ° to 100 ° in a direction in which the coil spring circulates and extends from a circumferential position in which an end surface of the coil spring sandwiches the one end of the elastic body. By providing a circumferential position of 90 ° as a central position in a circumferential region extending on both sides thereof, the coil spring can be prevented from coming into contact with the elastic body extending more reliably.

  The central angle on one side of the circumferential region extending on both sides of the central position is 35 ° to 50 °, preferably 40 °.

  The auto-tensioner according to the present invention is configured so that the elastic body is pressed against the inner peripheral surface of the inner cylindrical portion by an elastic restoring force, and one end of the elastic body is clamped between the end surface of the coil spring and the fixed member or the rotating member. Since the coil spring support portion that contacts the coil spring that expands and deforms on the inner circumference side of the elastic body that extends in an arc shape is provided, the elastic restoring force of the elastic body that is incorporated with a reduced diameter causes the circumferential direction The friction member is pressed against the inner peripheral surface of the inner cylindrical portion with a uniform pressing force, and the coil spring that expands and deforms is not in contact with the extending elastic body so that the friction member coupled to the elastic body is not pressed. Thus, the friction member can be prevented from being unevenly worn. In addition, the coil spring support portion also has an effect of suppressing the inclination of the coil spring that urges the rotation member from rotating around the coil center.

1 is a longitudinal sectional view showing an auto tensioner according to a first embodiment. Sectional view along the line II-II in FIG. The perspective view which shows the method of couple | bonding the leaf | plate spring and friction member of FIG. A longitudinal sectional view showing an auto tensioner according to a second embodiment. Sectional view along line VV in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. This auto tensioner adjusts the tension of a transmission belt that transmits the power of a crankshaft of an automobile engine to an auxiliary machine, and as shown in FIGS. 1 and 2, a fixing member attached to an engine block (not shown). The first cylindrical portion 1a provided on 1 and the second cylindrical portion 3a provided on the rotating member 3 on which the pulley 2 around which the transmission belt is wound and attached to the fixing member 1 are rotatably mounted. The one end side of the coil spring 4 that is overlapped inside and outside in the radial direction and accommodated on the inner diameter side of these cylindrical portions 1a and 3a is locked to the fixed member 1 and the other end side is locked to the rotating member 3, 3 is urged to rotate in one direction.

  In this embodiment, the first cylindrical portion 1a of the fixing member 1 is an inner cylindrical portion that is overlapped on the inside, and a metal leaf spring 5 as an elastic body extends along the inner peripheral surface of the first cylindrical portion 1a. Thus, the coil spring 4 extends in an arc shape on the outer peripheral side, an inward bent portion 5a is formed on one end side, and the other end side is a free end. The bent portion 5 a on one end side is sandwiched between the coil spring locking portion of the rotating member 3 on the side not including the inner cylindrical portion and the end surface 4 a of the coil spring 4. In addition, an arc-shaped friction member 6 is integrally coupled to the outer peripheral side of the leaf spring 5, and the friction member 6 is caused by the elastic restoring force of the leaf spring 5 that is incorporated with a reduced diameter on the inner diameter side of the first cylindrical portion 1 a. Is pressed against the inner peripheral surface of the first cylindrical portion 1a.

  The fixing member 1 includes a first cylindrical portion 1a as an inner cylindrical portion whose front end side overlaps the inner side of the second cylindrical portion 3a of the rotating member 3, and an inner cylindrical portion 1b formed inside the first cylindrical portion 1a. The first cylindrical portion 1a and the inner cylindrical portion 1b are connected to each other by an annular bottom wall portion 1c, and an engine block mounting flange portion 1d formed on the outer peripheral surface of the first cylindrical portion 1a. The shaft member 7 is fixedly fitted inside. An outward flange portion 7 a that prevents the rotating member 3 from coming off is formed at the tip of the shaft member 7.

  The rotating member 3 includes a second cylindrical portion 3a that overlaps the outside of the first cylindrical portion 1a, an inner cylindrical portion 3b that is formed inside the second cylindrical portion 3a, a second cylindrical portion 3a, and an inner cylindrical portion 3b. The inner bottom portion 3b is rotatably supported by the shaft member 7 via the bush 8. The annular bottom wall portion 3c for connecting the pulleys 2 and the pulley support portion 3d to which the pulley 2 is attached are provided. Further, a spiral surface 9 is formed on the inner side surface of the bottom wall portion 3c along the coil spring 4, and the spiral step surface 9a formed at the circumferential step portion of the spiral surface 9 is formed by the coil spring locking portion. It is said that. A cap body 10 that seals the inside of the auto tensioner is attached to the outer surface of the bottom wall portion 3c.

  One end side of the coil spring 4 is locked to the bottom wall portion 1 c side of the fixing member 1, and the end surface 4 a of the other end side is placed on a spiral step surface 9 a as a coil spring locking portion of the rotating member 3, and the leaf spring 5. It is latched so that the bending part 5a may be clamped. Although illustration is omitted, one end side of the coil spring 4 is fitted and locked in a groove or hole formed in the bottom wall portion 1c of the fixing member 1 or the inner cylinder portion 1b. One end may be locked in a spiral groove provided on the fixing member 1 side.

  A coil spring that extends in the axial direction from the bottom wall portion 3c of the rotating member 3 and abuts the coil spring 4 that expands in diameter on the inner peripheral side of the leaf spring 5 that extends to the outer peripheral side of the coil spring 4. A support unit 11 is provided. As shown in FIG. 2, the coil spring support portion 11 is arranged in a direction in which the coil spring 4 circulates and extends from a circumferential position where the end surface 4 a of the coil spring 4 sandwiches the bent portion 5 a of the leaf spring 5 to 80 ° to A circumferential position of 100 °, in the embodiment 90 °, is provided in a circumferential region extending from both sides at a central angle of 35 ° to 50 ° on one side and 40 ° in the embodiment, with the central position being 90 °.

  Since a load is applied to the ends of the coil spring 4 on the fixed member 1 side and the rotating member 3 side due to a moment generated by the torsional deformation of the coil spring 4, an external force is applied to the coil spring 4. Since the collapse of the coil spring 4 is greatest at the circumferential position of 80 ° to 100 ° from the end face 4a of the coil spring 4, it is preferable to provide the coil spring support portion 11 with the circumferential position as a center.

  In addition, when the circumferential region on one side of the coil spring support portion 11 is less than 35 °, the strength of the coil spring support portion 11 is insufficient, and the coil spring 4 may be damaged by the expanding force. Is subjected to vibration at the resonance frequency, the support area by the coil spring support portion 11 is narrow, so that the coil spring support portion 11 may come off. On the other hand, if the circumferential region on one side exceeds 50 °, the effective elastic deformation region of the coil spring 4 decreases, the spring constant increases, and there is a problem that the belt tension fluctuation when the auto tensioner swings increases.

  The coil spring support portion 11 prevents the coil spring 4 from coming into contact with the plate spring 5 by contacting the coil spring 4 whose diameter is increased and deformed on the inner peripheral side of the extending plate spring 5. Therefore, as will be described later, this auto tensioner has a first cylindrical portion having the friction member 6 as an inner cylindrical portion only by an elastic restoring force of a leaf spring 5 which is reduced in diameter and incorporated on the inner diameter side of the first cylindrical portion 1a. The friction member 6 coupled to the leaf spring 5 is not pressed against the inner peripheral surface of the first cylindrical portion 1a by the coil spring 4 that presses against the inner peripheral surface of 1a and expands in diameter. For this reason, the friction member 6 will not be unevenly worn by the non-uniform pressing force in the circumferential direction by the coil spring 4 that expands and deforms in diameter. Moreover, the coil spring support part 11 also suppresses the inclination from the coil center of the coil spring 4 which rotationally biases the rotation member 3.

  As shown in FIG. 3, the leaf spring 5 is provided with a bent portion 5a on one end side of an arc shape and an oval through hole 5b on the other end side. The friction member 6 is formed in a circular arc shape with a synthetic resin such as nylon, polyacetal, polyarylate or the like as a main component. A circular inward projection 6b is provided. The friction member 6 is assembled from the outer peripheral side of the leaf spring 5, the flange portion 6 a is placed along one width end surface of the leaf spring 5, and the protrusion portion 6 b is fitted into the through hole 5 b of the leaf spring 5. The spring 5 is integrally coupled. The leaf spring 5 to which the friction member 6 is integrally coupled is reduced in diameter and is incorporated on the inner diameter side of the first cylindrical portion 1a. In addition, you may integrally mold the friction member 6 by injection molding by using the leaf | plate spring 5 as an insert member.

  The operation of the above-described auto tensioner will be described below with reference to FIG. When the tension of the transmission belt wound around the pulley 2 increases, the rotation member 3 rotates in the clockwise belt slack direction against the urging force of the coil spring 4, and the end surface 4a of the coil spring 4 The bent portion 5a of the leaf spring 5 sandwiched between the spiral step surfaces 9a also rotates clockwise. At this time, since the leaf spring 5 is compressed in the circumferential direction against the frictional resistance of the friction member 6 by the bent portion 5a that rotates clockwise, the friction member 6 is placed on the inner peripheral surface of the first cylindrical portion 1a. The pressing force increases. Therefore, the rotation of the rotating member 3 in the belt slack direction is attenuated by strong damping, and string vibration and slip due to a sudden drop in tension of the transmission belt can be prevented. When the belt tension increases, the coil spring 4 tries to expand and deform, but the expansion of the coil spring 4 is restricted by the coil spring support portion 11 and the coil spring 4 presses the friction member 6. There is nothing.

  When the tension of the transmission belt decreases, the rotating member 3 is rotated counterclockwise by the biasing force of the coil spring 4, and is held between the end surface 4a of the coil spring 4 and the spiral step surface 9a. The bent portion 5a also rotates counterclockwise. At this time, since the leaf spring 5 is pulled in the circumferential direction against the frictional resistance of the friction member 6 by the bent portion 5a that rotates counterclockwise, the friction member 6 is brought to the inner peripheral surface of the first cylindrical portion 1a. The pressing force is reduced. Therefore, only weak damping acts on the rotation of the rotation member 3 in the belt tension direction, and the tension of the transmission belt can be quickly recovered. Thus, this auto tensioner has a damping characteristic that is asymmetric between the belt slack direction and the belt tension direction.

  4 and 5 show a second embodiment. This auto tensioner also adjusts the tension of the transmission belt that transmits the power of the crankshaft to the auxiliary machine. The fixing member 1 is attached to the engine block, and the rotating member 3 is rotatably supported by the fixing member 1. The basic component configuration including the coil spring 4, the leaf spring 5, and the friction member 6 that urges the rotation member 3 to rotate in one direction is the same as that of the first embodiment.

  In this embodiment, the second cylindrical portion 3a of the rotating member 3 is an inner cylindrical portion that is overlapped on the inner side, and is circular on the outer peripheral side of the coil spring 4 along the inner peripheral surface of the second cylindrical portion 3a. A bent portion 5 a formed on one end side of the leaf spring 5 extending in an arc shape is sandwiched between the coil spring locking portion of the fixing member 1 on the side not including the inner cylindrical portion and the end surface 4 a of the coil spring 4. ing. The friction member 6 integrally coupled to the outer peripheral side of the leaf spring 5 is pressed against the inner peripheral surface of the second cylindrical portion 3a by the elastic restoring force of the leaf spring 5 incorporated with a reduced diameter.

  The fixing member 1 includes a first cylindrical portion 1a that overlaps the outer side of the second cylindrical portion 3a of the rotating member 3, an inner cylindrical portion 1b that is formed inside the first cylindrical portion 1a, and a first cylindrical portion 1a. It comprises an annular bottom wall 1c that connects the inner cylinder 1b, and the shaft member 7 is fitted and fixed to the inner cylinder 1b. Further, a spiral surface 9 is formed on the inner side surface of the bottom wall portion 1c along the coil spring 4, and the spiral step surface 9a formed at the circumferential step portion of the spiral surface 9 is the coil spring locking portion. It is said that. An outward flange portion 7 a that prevents the rotating member 3 from coming off is formed at the tip of the shaft member 7.

  The rotating member 3 includes a second cylindrical portion 3a whose tip end overlaps the inside of the first cylindrical portion 1a, an inner cylindrical portion 3b formed inside the second cylindrical portion 3a, a second cylindrical portion 3a, and an inner cylinder. The inner bottom portion 3b is rotatably supported by the shaft member 7 via the bush 8 and includes an annular bottom wall portion 3c for connecting the portion 3b and a pulley support portion 3d to which the pulley 2 is attached. A cap body 10 that seals the inside of the auto tensioner is attached to the outer surface of the bottom wall portion 3c.

  One end side of the coil spring 4 is locked to the bottom wall portion 3 c side of the rotating member 3, and the end surface 4 a of the other end side is placed on the spiral step surface 9 a as a coil spring locking portion of the fixing member 1, and the leaf spring 5. It is latched so that the bending part 5a may be clamped. Although illustration is omitted, one end side of the coil spring 4 is fitted and locked in a groove or a hole formed in the bottom wall portion 3c or the inner cylinder portion 3b of the rotating member 3.

  A coil spring support that abuts the coil spring 4 that extends in the axial direction from the bottom wall portion 1c of the fixing member 1 and expands in diameter on the inner peripheral side of the leaf spring 5 that extends to the outer peripheral side of the coil spring 4. Part 11 is provided. As shown in FIG. 5, the coil spring support portion 11 has an end surface 4 a of the coil spring 4 that extends from a circumferential position where the end portion 4 a of the leaf spring 5 sandwiches the bent portion 5 a in a direction extending around the coil spring 4. A circumferential position of 100 °, in the embodiment 90 °, is provided in a circumferential region extending from both sides at a central angle of 35 ° to 50 ° on one side and 40 ° in the embodiment, with the central position being 90 °. The reason why the circumferential center position and the circumferential region of the coil spring support portion 11 are set in this way is as described above.

  Similar to the first embodiment, the coil spring support portion 11 is brought into contact with the coil spring 4 whose diameter is increased and deformed on the inner peripheral side of the extending plate spring 5 so that the coil spring 4 becomes a plate spring. Do not abut against 5. Therefore, the friction member 6 is pressed against the inner peripheral surface of the second cylindrical portion 3a only by the elastic restoring force of the leaf spring 5 that is reduced in diameter and incorporated in the inner diameter side of the second cylindrical portion 3a as the inner cylindrical portion. The friction member 6 does not wear unevenly due to a non-uniform pressing force in the circumferential direction by the coil spring 4 that expands and deforms in diameter. This coil spring support part 11 also suppresses the inclination from the coil center of the coil spring 4 that urges the rotation member 3 to rotate.

  As in the first embodiment, the leaf spring 5 is provided with a through hole on the other end side opposite to the bent portion 5a, and the friction member 6 is inward provided on one end side in the circumferential direction. These protrusions are fitted into the through-holes of the leaf spring 5 from the outer peripheral side, and are integrally coupled to the leaf spring 5.

  The operation of the above-described auto tensioner will be described below based on FIG. When the tension of the transmission belt increases, the rotating member 3 rotates in the clockwise belt slack direction. At this time, the leaf spring 5 in which the bent portion 5a is fixed to the spiral step surface 9a of the fixing member 1 is compressed in the circumferential direction by the clockwise frictional force applied to the friction member 6 from the second cylindrical portion 3a. Therefore, the force which presses the friction member 6 to the internal peripheral surface of the 2nd cylindrical part 3a becomes large. Therefore, the rotation of the rotating member 3 in the belt slack direction is attenuated by strong damping, and string vibration due to a sudden drop in tension of the transmission belt can be prevented.

  When the tension of the transmission belt decreases, the rotating member 3 rotates in the counterclockwise belt tension direction by the biasing force of the coil spring 4. At this time, the leaf spring 5 having the bent portion 5a fixed to the spiral step surface 9a is pulled in the circumferential direction by the counterclockwise frictional force applied to the friction member 6 from the second cylindrical portion 3a. The force which presses 6 to the internal peripheral surface of the 2nd cylindrical part 3a becomes small. Therefore, only weak damping acts on the rotation of the rotation member 3 in the belt tension direction. Thus, this auto tensioner also has an asymmetric damping characteristic between the belt slack direction and the belt tension direction.

  In each of the above-described embodiments, the coil spring support portion is provided only on the rotating member side or the fixed member side on the inner diameter side of the extending leaf spring, but on the opposite side to the region where the leaf spring does not extend. The fixing member may be provided on the fixing member side or the fixing member side. The coil spring support portion provided in the region where these leaf springs do not extend suppresses only the inclination of the coil spring from the coil center.

  In each of the above-described embodiments, the elastic body is a metal leaf spring, and a bent portion is formed on one end side of the coil spring, but the elastic body is a synthetic resin arcuate sleeve or the like. It is also possible to form a protruding portion, a bulging portion or the like on one end side of the coil spring so as to be sandwiched between the end surfaces of the coil spring.

  In each of the above-described embodiments, the tension of the transmission belt that transmits the power of the crankshaft of the automobile engine to the auxiliary machine is adjusted. However, the auto tensioner according to the present invention has the tension of the transmission belt of another belt transmission mechanism. It can also be used for adjusting the angle.

DESCRIPTION OF SYMBOLS 1 Fixed member 1a 1st cylindrical part 1b Inner cylinder part 1c Bottom wall part 1d Flange part 2 Pulley 3 Rotating member 3a 2nd cylindrical part 3b Inner cylinder part 3c Bottom wall part 3d Pulley support part 4 Coil spring 4a End surface 5 Leaf spring 5a bent portion 5b through hole 6 friction member 6a flange portion 6b projection portion 7 shaft member 7a flange portion 8 bush 9 spiral surface 9a spiral step surface (coil spring locking portion)
10 Cap body 11 Coil spring support part

Claims (3)

A fixing member provided with a first cylindrical portion;
Provided is a second cylindrical portion that is coaxially disposed so that at least a part of the first cylindrical portion overlaps the inside and outside in the radial direction, and is rotatably supported with respect to the fixing member, and a pulley around which a belt is wound. An attachable rotating member;
Housed on the inner diameter side of the two cylindrical portions that overlap the inside and outside in the radial direction, one end is locked to the fixing member, and the other end is locked to the rotating member, and the rotation with respect to the fixing member A coil spring that biases the member in one direction;
One end is sandwiched between one of the fixing member and the rotating member and the end surface of the coil spring, the other end is a free end, and is provided on the other of the fixing member and the rotating member. An elastic body extending in an arc shape on the outer peripheral side of the coil spring along the inner peripheral surface of the inner cylindrical portion overlapping the inner and outer sides of the direction;
In an auto tensioner that is coupled to the elastic body and includes a friction member that contacts an inner peripheral surface of the inner cylindrical portion,
The elastic body is pressed against the inner peripheral surface of the inner cylindrical portion by an elastic restoring force,
An auto-tensioner, wherein a coil spring support portion is provided on one of the fixing member and the rotating member so as to contact the coil spring whose diameter is increased and deformed on the inner peripheral side of the elastic body.   The coil spring support portion is centered at a circumferential position in a range of 80 ° to 100 ° in a direction in which the coil spring circulates and extends from a circumferential position where an end surface of the coil spring sandwiches the one end of the elastic body. The auto-tensioner according to claim 1, wherein the auto-tensioner is provided in a circumferential region extending on both sides as a position.   The auto tensioner according to claim 2, wherein a central angle on one side of a circumferential region extending on both sides of the central position is set to 35 ° to 50 °.

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