JP2017096296A - Automatic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent foreign matter from entering a storage space with a simple structure.SOLUTION: An automatic tensioner includes: a movable member 3 configured to rotatably support a tensioner pulley 107; a fixing member 2 configured to rotatably support the movable member 3; a coil spring 4 configured to energize the movable member 3 in a pressing direction; and an insert bearing 5 and a spring support 7 configured to attenuate rotation of the movable member 3 with slide friction. In the automatic tensioner, a housing part 15 formed by the movable member 3 and the fixing member 2 is arranged in parallel with the pulley 107; at an outer peripheral portion of the housing 15, formed is a clearance 16 communicating with a storage space 14 storing the insert bearing 5 and the spring support 7; and at the movable member 3, provided is a dust prevention wall 23 partitioning between the clearance 16 of the housing part 15 and the pulley 107.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an auto tensioner that applies a predetermined tension to a belt by pressing a pulley against the belt.

  2. Description of the Related Art Conventionally, an auto including a movable member that rotatably supports a pulley and a fixed member that rotatably supports the movable member at a position that is eccentric from the rotation axis of the pulley and that is rotatable about an axis parallel to the rotation axis. Tensioners are known. This type of auto tensioner is disclosed in, for example, Patent Document 1 and Patent Document 2.

  In Patent Document 1, a movable member and a fixed member form a housing part having a housing space around the rotation axis of the movable member, and the housing part is located at a side of the pulley in the radial direction with an interval. A tensioner is disclosed. In this autotensioner, a torsion coil spring that urges the movable member in the pressing direction of the pulley and a bush that attenuates the rotation of the movable member by sliding frictional force are accommodated in the housing space of the housing portion. In the outer peripheral portion of the housing part along the rotation direction of the movable member, a gap is formed between the movable member and the fixed member so as to communicate with the accommodation space.

  In Patent Document 2, a housing portion that accommodates a torsion coil spring and a bush, which are formed by a movable member and a fixed member, and is similar to the auto tensioner of Patent Document 1, is disposed close to the direction along the rotation axis of the pulley. An auto tensioner is disclosed. In this auto tensioner, a labyrinth structure is formed in the gap between the movable member and the fixed member forming the housing portion, and the labyrinth structure prevents foreign matter and the like from entering the housing space of the housing portion. .

JP 2006-162006 A JP 2006-057443 A

  In the auto tensioner of Patent Document 1, foreign matter such as dust that is wound up by the rotation of the pulley accompanying the running of the belt when used is likely to enter the accommodation space through the gap in the outer peripheral portion of the housing portion. If a foreign substance enters the housing space of the housing portion, the damping member such as a bush may be prematurely worn or damaged, and the sliding frictional force by the damping member, and thus the damping characteristics of the auto tensioner may become unstable.

  Then, it is possible to apply the labyrinth structure with which the autotensioner of patent document 2 is provided also to the clearance in the housing part of the autotensioner of patent document 1. However, the labyrinth structure is a structure in which concave and convex shapes are formed on the movable member and the fixed member, and the side walls constituting the concave and convex shape are overlapped with a slight gap therebetween. It is necessary to set an appropriate gap between the side walls while paying attention to the fact that the side walls of the shape interfere with each other.

  Therefore, the movable member and the fixed member, and the mold structure for producing them are complicated, and the inspection process of the movable member and the fixed member is increased in order to inspect the occurrence of the trouble caused by providing the labyrinth structure. This increases the cost of the auto tensioner. Furthermore, the complexity of the structure of the movable member and the fixed member increases the size of the parts, which increases the size and weight of the auto tensioner, thereby impairing the mountability of the auto tensioner with respect to the belt transmission system.

  The present invention has been made in view of such points, and an object of the present invention is to prevent foreign matter from entering the housing space of the housing portion with a simple structure.

  In order to achieve the above object, according to the present invention, the movable member is provided with a wall portion that prevents foreign matter from entering the housing space from the gap of the housing portion.

  Specifically, the present invention is directed to an auto tensioner that applies a predetermined tension to a belt by pressing the pulley against the belt, and provides the following solution.

  That is, the first invention provides a movable member that rotatably supports the pulley, a support member that rotatably supports the movable member in a pressing direction in which the pulley presses the belt, and biases the movable member in the pressing direction. And an attenuating member for attenuating the rotation of the movable member by the sliding frictional force. The movable member and the fixed member form a housing portion having an accommodating space for accommodating the biasing member and the damping member. This housing part is located on the side of the pulley in the radial direction with a space therebetween. A gap communicating with the accommodation space is formed in the outer peripheral portion of the housing portion along the rotation direction of the movable member. The first invention is characterized in that the movable member is provided with a dust-proof wall separating the gap between the housing portion and the pulley.

  According to this configuration, since the dust-proof wall is provided between the clearance of the housing portion and the pulley, even if foreign matter such as dust is wound up by rotation of the pulley accompanying the running of the belt when the auto tensioner is used, it is wound up. The foreign matter is blocked by the dust-proof wall, does not reach the housing portion, flows between the pulley and the dust-proof wall in the rotational direction of the pulley, and is discharged between the two. Thereby, it can prevent that a foreign material penetrate | invades into accommodation space from the clearance gap between housing parts.

  According to a second aspect of the present invention, in the auto tensioner of the first aspect, the dust-proof wall is provided in a curved shape extending along the outer peripheral surface of the pulley.

  According to this configuration, since the dust-proof wall has a curved shape along the outer peripheral surface of the pulley, the foreign matter wound up by the rotation of the pulley is separated from the housing portion along the rotation direction of the pulley from between the pulley and the dust-proof wall. Discharged. As a result, foreign matter discharged from between the pulley and the dust-proof wall crosses the dust-proof wall, that is, wraps around the side of the dust-proof wall and does not flow to the housing part side, and enters the housing space of the housing part. Can be suitably prevented.

  According to a third aspect of the present invention, in the auto tensioner according to the first or second aspect, the distance between the dust-proof wall and the outer peripheral surface of the pulley is forward in the pulley rotation direction with respect to a portion of the pulley around which the belt is wound. It is characterized by a minimum width at the end (front end) located.

  If the distance between the dust-proof wall and the outer peripheral surface of the pulley is the minimum width at the middle of the dust-proof wall or at the end opposite to the front end, or if it is evenly spaced throughout, the rotation of the pulley There is a possibility that the foreign matter wound up by the bite is caught between the pulley and the dust-proof wall and hinders the rotational operation of the pulley. On the other hand, according to the above configuration, since the distance between the dust-proof wall and the outer peripheral surface of the pulley is set to the minimum width at the front end of the dust-proof wall, the foreign matter wound up by the rotation of the pulley is between the pulley and the dust-proof wall. Can be prevented, and the rotation of the pulley can be prevented from being hindered by such biting of foreign matter.

  According to the present invention, it is possible to prevent foreign matter from entering the housing space of the housing portion with a simple structure such as providing a dustproof wall.

1 is an overall perspective view of an auto tensioner according to an embodiment. It is a top view of the auto tensioner concerning an embodiment. It is a side view of the auto tensioner concerning an embodiment. It is sectional drawing of the auto tensioner in the IV-IV line of FIG. It is a figure which shows the pulley layout of the belt transmission system using the auto tensioner which concerns on embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

  1 to 4 show the configuration of the auto tensioner 1 according to this embodiment. FIG. 1 is an overall perspective view of the auto tensioner 1. FIG. 2 is a plan view of the auto tensioner 1. FIG. 3 is a side view of the auto tensioner 1. 4 is a cross-sectional view of the auto tensioner 1 taken along line IV-IV in FIG. FIG. 5 shows a pulley layout of the belt transmission system 100 using the auto tensioner 1 according to this embodiment.

  The auto tensioner 1 is used in a belt transmission system 100 for driving auxiliary equipment mounted on an automobile. In the belt transmission system 100, for example, a transmission belt 101 such as a V-ribbed belt as shown in FIG. 5 is wound around six pulleys 102 to 107 including four rib pulleys 102 to 105 and two flat pulleys 106 and 107. It is a serpentine drive transmission system.

  The belt transmission system 100 includes, for example, a crank pulley 102 attached to a crankshaft of an in-vehicle engine, a compressor pulley 103 attached to a rotation shaft of an air conditioner compressor (auxiliary machine), and a water pump (auxiliary machine). A water pump pulley 104 attached to the rotating shaft, an alternator pulley 105 attached to the rotating shaft of the alternator (auxiliary machine), a PS pump pulley 106 attached to the rotating shaft of the power steering pump (auxiliary machine), an auto A tensioner pulley 107 attached to the tensioner 1.

  Among these six pulleys 102 to 107, the water pump pulley 104 and the tensioner pulley 107 are flat pulleys, and the other pulleys 102, 103, 105, and 106 are all rib pulleys. In the case of the rib pulleys 102, 103, 105, and 106, the transmission belt 101 is in a positive bending state in which the inner peripheral surface of the belt is in contact with the pulley, and in the flat pulleys 104 and 107, the outer peripheral surface of the belt is in contact with the pulley. Each is wound in the reverse bending state, and travels between the pulleys 102 to 107 by the rotation of the engine to drive each auxiliary machine.

  The auto tensioner 1 is disposed on a slack side span on the side of the transmission belt 101 that comes out of the crank pulley 106, and the tension belt pulley 107 is pressed against the slack side span from the belt outer peripheral surface side to the transmission belt 101 with a predetermined tension. A tension is applied and the tension of the transmission belt 101 is automatically adjusted.

  As shown in FIGS. 1 to 4, the auto tensioner 1 is fixed to a fixed body 2 such as a chassis of a vehicle body or an engine, and can be rotated around a rotation axis by being assembled to the fixed member 2. The movable member 3 supported by the torsion coil spring 4, the torsion coil spring 4 as a biasing member that biases the movable member 3 in a predetermined direction relative to the fixed member 2, and the rotation of the movable member 3 is attenuated by a sliding frictional force. And an insert bearing 5, a thrust washer 6, and a spring support 7 as damping members to be driven.

  The fixing member 2 is made of a metal such as an aluminum alloy, and is molded by a known method. The fixing member 2 includes a bottomed cylindrical rear cup portion 8 having an open end, a shaft portion 9 provided concentrically in the center of the bottom wall of the rear cup portion 8, and an attachment provided on an outer peripheral portion of the rear cup portion 8. Bracket 10. On the peripheral wall of the rear cup portion 8, although not shown, a spring locking portion is formed that includes a notch obtained by cutting the peripheral wall in the radial direction or a through-hole penetrating the peripheral wall.

  The shaft portion 9 is formed in a hollow cylindrical shape having a small-diameter center hole 9 a, and the tip side protrudes from the opening of the rear cup portion 8. The center hole 9a of the shaft portion 9 constitutes a bolt insertion hole. Further, the mounting bracket 10 is formed with a bolt insertion hole 10a. The fixing member 2 is fixed to the fixed body by bolts (not shown) in these bolt insertion holes 9a and 10a. The fixed member 2 supports the movable member 3 so as to be rotatable in a pressing direction in which the tensioner pulley 107 presses the transmission belt 101 (hereinafter referred to as “belt pressing direction”).

  The movable member 3 is made of a metal such as an aluminum alloy, for example, and is molded by a known method. The movable member 3 includes a bottomed cylindrical front cup portion 11 having an open end, a cylindrical boss portion 12 concentrically provided in the center of the bottom wall of the front cup portion 11, and an outer periphery of the front cup portion 11. And an arm portion 13 extending outward in the radial direction from the portion. On the peripheral wall of the front cup portion 11, although not shown, a spring locking portion including a notch obtained by notching the peripheral wall in the radial direction or a through hole penetrating the peripheral wall is formed.

  The outer diameter of the front cup portion 11 is substantially the same as the outer diameter of the rear cup portion 8. The opening end of the front cup portion 11 faces the opening end of the rear cup portion 8 with a gap in the direction along the rotational axis P of the movable member 3, that is, the center line of the boss portion 12. The front cup portion 11 and the rear cup portion 8 form a housing portion 15 having a housing space 14 for housing the torsion coil spring 4, the insert bearing 5, the spring support 7, and the like.

  The housing portion 15 is located at a lateral side in the radial direction of the tensioner pulley 107 and is disposed in parallel with the tensioner pulley 107. In the outer peripheral portion of the housing portion 15 along the rotational direction of the movable member 3, a gap 16 communicating with the accommodation space 14 is formed over the entire circumference. The gap 16 is a gap between the opening ends of the rear cup portion 8 and the front cup portion 11 facing each other.

  The boss portion 12 protrudes from the opening of the front cup portion 11 at the distal end side, and is externally fitted to the shaft portion 9 of the fixing member 2 from the distal end side. An insert bearing 5 is sandwiched between the outer peripheral surface of the shaft portion 9 of the fixed member 2 and the inner peripheral surface of the boss portion 12 of the movable member 3. The movable member 3 is rotatably supported on the shaft portion 9 of the fixed member 2 by the boss portion 12 via the insert bearing 5.

  The insert bearing 5 is made of a synthetic resin such as nylon and has a cylindrical shape with both ends opened. Both the inner and outer surfaces of the insert bearing 5 have the outer peripheral surface of the shaft portion 9 of the fixed member 2 and the inner peripheral surface of the boss portion 12 of the movable member 3, and the distal end portion of the boss portion 12 is on the proximal end side. It is formed in a cross-sectional taper shape having a slightly smaller diameter than the portion.

  Although not shown, a keyway extending in a direction along the rotation axis P of the movable member 3 is formed on the outer peripheral surface of the shaft portion 9 of the fixed member 2. On the inner peripheral surface of the insert bearing 5 against this, a key projection piece that fits into the key groove is provided. The insert bearing 5 is stopped on the fixed member 2 side by a fitting structure of these key grooves and key projecting pieces.

  A front plate 17 made of a disk-shaped metal plate is fixed to the tip end portion of the shaft portion 9 of the fixing member 2 so as not to rotate by caulking or the like. The movable member 3 is secured from the shaft portion 9 by the front plate 17. A thrust washer 6 is sandwiched between the front plate 17 and the end face of the boss portion 12. The thrust washer 6 is an annular thin plate component made of the same material as that of the insert bearing 5, for example.

  A shaft 18 that extends in the direction of the axis Q parallel to the rotation axis P of the movable member 3 is provided at the tip of the arm 13. A tensioner pulley 107 is rotatably attached to the shaft portion 18 in a state where the tensioner pulley 107 is retained by a pulley bolt 19. A dust shield 20 made of a metal plate that covers the bearing 108 of the tensioner pulley 107 is sandwiched and fixed between the flange portion 19 a of the pulley bolt 19 and the tensioner pulley 107.

  Further, rib portions 21 that are integrated with the housing portion 15 are provided at both ends of the arm portion 13 in the width direction. These rib portions 21 are provided in order to ensure the strength and rigidity of the arm portion 13 without increasing the weight of the arm portion 13 as much as possible, and between the rib portions 21 of the peripheral wall of the front cup portion 11 of the movable member 3. Together with the positioned portion, a U-shaped portion opened toward the tensioner pulley 107 side is formed.

  In addition, an engagement piece 22 having a recess 22 a that opens to the fixing member 2 side is provided at a position away from the arm portion 13 at the outer peripheral portion of the front cup portion 11. This engagement piece 22 is used to rotate and displace the arm portion 13 against the spring force of the torsion coil spring 4 (spring elastic force) in the operation of incorporating the auto tensioner 1 into the belt transmission device 100. It is a part with which a tool is engaged.

  The torsion coil spring 4 is disposed between the bottom wall of the rear cup portion 8 of the fixed member 2 and the bottom wall of the front cup portion 11 of the movable member 3 so as to surround the boss portion 12 of the movable member 3. . The torsion coil spring 4 has a coil portion, which is a main body, that has a right-handed shape, and has one end portion and the other end portion that protrude outward from the main body in the radial direction.

  One end of the torsion coil spring 4 is hooked and stopped by the spring locking hole provided in the rear cup portion 8 of the fixing member 2. Further, the other end of the torsion coil spring 4 is hooked and stopped by the spring locking hole provided in the front cup portion 11 of the movable member 3. As a result, both ends of the torsion coil spring 4 are restricted from moving in the circumferential direction.

  The torsion coil spring 4 is accommodated in the housing portion 15 in a state where the coil portion is twisted in the direction of reducing the diameter and compressed in the axial direction. As a result, the thrust washer 6 is pressed between the bottom wall of the front cup portion 11 of the movable member 3 and the front plate 17 by the spring force of the torsion coil spring 4 (elastic return force of the spring). It has become. Further, the movable member 3 is constantly urged so as to rotate around the rotation axis P in the belt pressing direction by a torsion torque in a direction in which the coil diameter of the torsion coil spring 4 increases.

  A spring support 7 is provided between the coil portion of the torsion coil spring 4 and the boss portion 12 of the movable member 3. The spring support 7 has a hooked cylindrical shape as a whole. Specifically, the spring support 7 includes a cylindrical main body portion 7a and an outward flange-shaped flange portion 7b provided at an opening edge on one side of the main body portion 7a.

  The main body portion 7 a of the spring support 7 is externally fitted to the boss portion 12 of the movable member 3, and the inner peripheral surface thereof is slidably in contact with the outer peripheral surface of the boss portion 12. The flange portion 7 b of the spring support 7 is pressed against the inner surface of the bottom wall of the rear cup portion 8 by the urging force of the torsion coil spring 4. Thereby, the spring support 7 is fixed to the fixing member 2 side.

  In the auto tensioner 1 of this embodiment, a dust-proof wall 23 that separates the gap 16 of the housing portion 15 from the tensioner pulley 107 is provided on the arm portion 13 of the movable member 3 near the tensioner pulley 107. Yes. The dust-proof wall 23 is a single plate-like object, and is provided over the entire width direction (vertical direction in FIG. 3) of the arm portion 13 between the end portions of the rib portions 21 on the tensioner pulley 107 side. The curved shape extends along the outer peripheral surface of the tensioner pulley 107.

  Specifically, the dust-proof wall 23 is an end (hereinafter, referred to as the forward direction in the rotational direction Dr of the tensioner pulley 107) with respect to a portion 107a around which the transmission belt 101 is wound (a belt-wrapped portion) 107a of the tensioner pulley 107. A front end 23a and a center C of the tensioner pulley 107. The front end 23a and the center C of the tensioner pulley 107 are arranged at the rear end of the tensioner pulley 107 in the rotational direction Dr (hereinafter referred to as "rear end") 23b. On the connecting line L, the tensioner pulley 107 is formed in an arc shape centered on an eccentric position P that is separated from the center C of the tensioner pulley 107 by a predetermined distance X in a direction opposite to the side end 23a. The front end 23 a of the dust-proof wall 23 constitutes an end that serves as an entrance to the space between the tensioner pulley 107 and the dust-proof wall 23 in the rotation direction Dr of the tensioner pulley 107. On the other hand, the rear end 23 b of the dustproof wall 23 constitutes an end serving as an outlet from the space between the tensioner pulley 107 and the dustproof wall 23 in the rotation direction of the tensioner pulley 107.

  When the radius of the tensioner pulley 107 is R and the distance between the front end 23a of the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107 is A, the arc surface on the tensioner pulley 107 side of the dust-proof wall 23 is the eccentric position. A shape drawn by an arc-shaped locus having a distance (radius) from P as R + A + X. The distance d between the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107 has a minimum width at the front end 23a of the dust-proof wall 23, and gradually increases along the dust-proof wall 23 toward the rear end 23b. The rear wall 23b of the dustproof wall 23 has the maximum width. That is, the distance A between the front end 23 a of the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107 is set smaller than the distance B between the rear end 23 b of the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107.

  In the automatic tensioner 1 configured as described above, in the belt transmission device 100, the tensioner pulley 107 is pressed against the transmission belt 101 by the urging force of the torsion coil spring 4 acting on the movable member 3 in the belt pressing direction. Tension is applied. Thus, the tension of the transmission belt 101 wound around the tensioner pulley 107 is automatically adjusted so as not to loosen.

  Further, in this auto tensioner 1, when the tension of the transmission belt 101 wound around the tensioner pulley 107 increases, the main body portion 7a of the spring support 7 is caused by the inward pressing force of the torsion coil spring 4 in the radial direction. When pressed against the boss portion 12 of the movable member 3, a sliding frictional force is generated between a part of the inner peripheral surface of the main body portion 7 a and a part of the outer peripheral surface of the boss portion 12. Further, at this time, the boss portion 12 is pressed against the insert bearing 5 by the pressing force, and a sliding frictional force is also generated between a part of the inner peripheral surface of the boss portion 12 and a part of the outer peripheral surface of the insert bearing 5. . At the same time, the thrust washer 6 is pressed against the bottom wall of the front cup portion 11 by the elastic restoring force in the axial direction of the torsion coil spring 4 to generate a sliding frictional force. The rotation of the movable member 3 is attenuated by at least these three sliding frictional forces. Thereby, when the tension of the transmission belt 101 increases rapidly, the rotation of the movable member 3 is suppressed, and the transmission belt 101 is prevented from flapping.

  According to the auto tensioner 1, the dust-proof wall 23 is provided between the gap 16 of the housing portion 15 and the tensioner pulley 107. Therefore, when the auto tensioner 1 is used, the tensioner pulley 107 is moved along with the travel of the transmission belt 101. Even if foreign matter such as dust is wound up by rotation, the wound up foreign matter is blocked by the dust-proof wall 23 and does not reach the housing portion 15, and the movable member 3 rotates between the tensioner pulley 107 and the dust-proof wall 23. Flows outward in the direction and is discharged from between them.

  Moreover, in the auto tensioner 1, the dust-proof wall 23 has a curved shape along the outer peripheral surface of the tensioner pulley 107. It is discharged in a direction away from the housing portion 15 along the rotational direction of 107. As a result, foreign matter discharged from between the tensioner pulley 107 and the dust-proof wall 23 can be prevented from flowing over the dust-proof wall 23, that is, around the side of the dust-proof wall 23 and flowing toward the housing portion 15. . As described above, foreign matter can be prevented from entering the housing space 14 from the gap 16 of the housing portion 15.

  Further, according to the auto tensioner 1, since the distance d between the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107 is set to the minimum width at the front end 23a of the dust-proof wall 23, the foreign matter wound up by the rotation of the tensioner pulley 107 is prevented. It is possible to avoid being caught between the tensioner pulley and the dust-proof wall 23, and to prevent the rotational operation of the tensioner pulley 107 from being hindered by such a foreign matter biting.

  As mentioned above, although preferable embodiment of this invention was described, the technical scope of this invention is not limited to the range as described in the said embodiment. It is to be understood by those skilled in the art that the above-described embodiments are exemplifications, and that various modifications can be made to combinations of the respective constituent elements, and such modifications are also within the scope of the present invention.

  For example, the following embodiment may be configured as follows.

  The dust-proof wall 23 may be a flat plate extending in a straight line, a parabola-like shape, or a shape similar to a spline curve, and extends along the outer peripheral surface of the housing portion 15. It may be a curved shape. Also in these cases, the distance d between the dust-proof wall 23 and the outer peripheral surface of the tensioner pulley 107 is the front end of the dust-proof wall 23 from the viewpoint of preventing foreign matter from being caught between the tensioner pulley 107 and the dust-proof wall 23. It is preferable that the minimum width is 23a.

  Moreover, the dust-proof wall 23 may be provided not in the whole in the width direction of the arm part 13, but in one part, and may be divided | segmented into multiple instead of one plate-shaped object. Further, the dustproof wall 23 may be provided in a portion of the arm portion 13 near the housing portion 15.

  In short, in the auto tensioner 1, the housing portion 15 and the tensioner pulley 107 are arranged in parallel, and the dust-proof wall 23 prevents the foreign matter from entering the gap 16 of the housing portion 15 between the both 15 and 107. It may be provided so as to play a role.

  As described above, the present invention is useful for an auto tensioner that applies a predetermined tension to a belt by pressing a pulley against the belt.

DESCRIPTION OF SYMBOLS 1 ... Auto tensioner, 2 ... Fixed member, 3 ... Movable member, 4 ... Torsion coil spring,
5 ... Insert bearing (damping member), 6 ... Thrust washer (damping member),
7 ... Spring support (damping member), 8 ... Rear cup part,
8a ... Center hole (bolt insertion hole), 9 ... Shaft, 9a ... Bolt insertion hole,
10 ... Mounting bracket, 10a ... Bolt insertion hole, 11 ... Front cup part,
12 ... Boss part, 13 ... Arm part, 14 ... Accommodating space, 15 ... Housing part, 16 ... Gap,
17 ... Front plate, 18 ... Shaft, 19 ... Pulley bolt, 19a ... Butt,
20 ... Dust shield, 21 ... Rib part, 22 ... Engagement piece, 22a ... Recess, 23 ... Dust barrier,
23a ... front end of dust-proof wall, 23b ... rear end of dust-proof wall, 100 ... belt transmission,
101 ... Transmission belt, 102 ... Crank pulley, 103 ... Compressor pulley,
104 ... Water pump pulley, 105 ... Alternator pulley,
106 ... PS pump pulley, 107 ... Tensioner pulley

Claims (3)

An auto tensioner that applies a predetermined tension to the belt by pressing a pulley against the belt,
A movable member that rotatably supports the pulley;
A fixed member that rotatably supports the movable member in a pressing direction in which the pulley presses the belt;
A biasing member that biases the movable member in the pressing direction;
An attenuation member that attenuates the rotation of the movable member by a sliding frictional force,
The movable member and the fixed member form a housing portion having an accommodating space for accommodating the biasing member and the damping member,
The housing part is located at a lateral side in the radial direction of the pulley,
In the outer peripheral portion of the housing part along the rotation direction of the movable member, a gap that leads to the accommodation space is formed,
An auto tensioner, wherein the movable member is provided with a dust-proof wall that separates the clearance between the housing portion and the pulley. The auto tensioner according to claim 1,
The auto-tensioner, wherein the dust-proof wall is provided in a curved shape extending along the outer peripheral surface of the pulley. In the auto tensioner according to claim 1 or 2,
The distance between the dust-proof wall and the outer peripheral surface of the pulley has a minimum width at an end positioned forward in the rotation direction of the pulley with respect to a portion of the pulley around which the belt is wound. Auto tensioner.

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