JP2005273896A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auto tensioner formed by further improving a damper effect between a fixed member and a movable member. <P>SOLUTION: This auto tensioner 1 for properly maintaining the tension of a belt comprises the fixed member 3 fixed to a vehicle body, the movable member 2 of an arm-like structure rotatably supported on the fixed member 3, a pulley 7 fitted to the arm-like tip part of the movable member 2 and engaged with a belt, a coiled spring 4 energizing the movable member 2 against the fixed member 3 in a specified direction, and a damper member 5 interposed between the movable member 2 and the fixed member 3 and attenuating/converging the swing of the movable member 2. A film-like viscous fluid 14 as a damper member 5 is interposed in a clearance between the movable member 2 and the fixed member 3 to provide the shearing viscous resistance of a viscous fluid against the rotation of the movable member 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an auto tensioner for automatically maintaining a belt tension appropriately.

  An auto tensioner is used as a device for maintaining an appropriate tension of a belt for driving an auxiliary machine of an automobile engine. In general, this auto tensioner automatically controls the belt tension using the force of the spring, but as a method of damping and converging the swing of the auto tensioner, there are a hydraulic damper method and a friction damper method. Broadly divided. Of these, the latter friction method generally comprises a movable member to which a pulley is attached and a fixed member that is fixed to the vehicle body, and both move relative to each other via a shaft portion so as to make the belt tension as constant as possible by a torsion spring.

  In this case, a sliding member having a predetermined coefficient of friction is arranged on the shaft portion between the movable member and the fixed member, and by applying an appropriate surface pressure, the movable member is caused by frictional energy generated during sliding. Is damped and converged in a short time to keep the belt tension as constant as possible.

  In general, the movable member and the fixed member are made of an aluminum alloy, and by sliding the aluminum alloy and the sliding member, the belt tension is kept constant, and friction energy is generated between them. It is a mechanism that attenuates the swing of the movable member in a short time. In the auto tensioner having such a structure, since the sliding member rubs against the aluminum alloy, a frictional force necessary to attenuate the swing of the movable part, that is, an appropriate coefficient of friction is necessary, and wear due to the aluminum alloy is required. There was a need for less.

  Therefore, a synthetic resin having a relatively small friction coefficient is generally used as the sliding member. Among them, there are many examples using nylon 66, nylon 46 or polyacetal. As another example, Patent Document 1 proposes a polyether sulfone resin blended with a polyterolafluoroethylene resin or an aramid fiber.

  In another auto tensioner, a multi-plate type viscous vibration absorbing means (damper) is provided in a space provided in the fixed shaft and the swing sleeve. This multi-plate type viscous vibration absorbing means has an annular plate member stacked in an empty chamber to increase the contact area, and a gap is filled with a viscous fluid such as silicone oil, and is disclosed in Patent Document 2.

  However, this nylon 66 has a low glass transition temperature and a low deflection temperature under load, so that it easily deforms when the temperature of the friction material rises due to frictional heat or the like, and easily adheres to the counterpart material (aluminum alloy). There is a problem, and since general nylon absorbs moisture and expands, it becomes higher temperature due to frictional heat, and wear of the sliding surface is increased, which may shorten the life. Polyacetal, on the other hand, has a slightly higher deflection temperature than nylon 66 and the like, but there is no decisive difference, and auto-tensioners that operate in a high temperature environment and have a large surface pressure on the friction surface have increased wear. was there.

  The auto tensioner is a device that operates in a relatively high temperature environment in the engine room of a car, and the sliding member itself is a mechanism that attenuates the swing of the movable part of the auto tensioner by frictional force. It tends to be hot. Although general nylon 66 or polyacetal has good slidability and wear resistance at a specific temperature, its deformation resistance and wear resistance in the use environment of the auto tensioner described above. However, it is not always sufficient, and there is a problem that the damping performance is likely to vary due to the influence of the frictional force depending on the surface roughness of the sliding member itself and the roundness of the movable member and the fixed member.

  On the other hand, when the multi-plate type viscous vibration absorbing means is used, the belt tension can be stably maintained. However, since the plate member is a complicated structure, the number of parts is increased and the cost is increased. In order to produce a damping force, the annular vacant chamber that accommodates the multi-plate viscous vibration absorbing means has a decisive problem that the distance from the shaft center increases and its volume increases and the auto tensioner becomes structurally large. .

JP-A-8-42649 Japanese Patent Publication No.8-10020

  The present invention is intended to improve the conventional problems, and an object of the present invention is to provide an auto tensioner in which the damper effect between the fixed member and the movable member is further improved.

  In the first aspect of the present invention, the fixing member fixed to the vehicle body, the movable member of the arm-like structure that is rotatably supported by the fixing member, and the belt provided at the arm-like tip of the movable member. An engaging pulley; a coil spring that biases the movable member in a predetermined direction relative to the fixed member; and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member. An auto-tensioner for maintaining a moderate belt tension, wherein the viscous fluid shears against the rotation of the movable member by interposing a film-like viscous fluid as the damper member in the gap between the movable member and the fixed member. A viscous resistance force is applied, and a large damping force is exerted. The auto tensioner is compact and has a small number of parts.

  In the invention according to claim 2 of the present application, an autotensioner in which a viscous fluid is sealed in an annular space formed by a gap between the fixed member and the movable member and shear viscosity resistance force of the viscous fluid resisting the rotation of the movable member is applied. It is in. By changing the thickness of the viscous fluid enclosed in the annular vacant space, the shear viscous resistance force resisting the rotation of the movable member can be adjusted.

  In the invention according to claim 3 of the present application, the reservoir groove for the viscous fluid is provided in the auto tensioner provided at the boundary between the annular cavity and the seal material, and the viscous fluid is temporarily stored in the reservoir groove so that the seal material is The viscous fluid leakage is reduced, and the damper effect can be maintained for a long time.

  In the invention according to claim 4 of the present application, the communication groove of the viscous fluid is provided in the auto tensioner provided on the inner wall surface of at least one of the fixed member and the movable member forming the annular vacancy, and the flow of the viscous fluid is restricted and disturbed. It is possible to prevent the generation of a flow, prevent the accumulation of air at the interface between the movable member and the fixed member, and generate a uniform viscous resistance between the circumferential surface of the annular cavity and the viscous fluid. it can.

  In the invention according to claim 5 of the present application, the annular vacancy is in the auto tensioner arranged on the outer side from the position of the coil spring, and the position of the annular vacancy is arranged away from the swivel shaft, thereby increasing the torque. A large damping force is generated.

  In the invention described in claim 6, the annular vacancy formed in the gap between the fixed member and the movable member is an auto tensioner formed in a conical shape, and the gap between the two is adjusted by adjusting the movement of the fixed member and the movable member. Can be adjusted.

  According to the seventh aspect of the present invention, the fixing member fixed to the vehicle body, the movable member of the arm-like structure that is rotatably supported by the fixing member, and the belt provided at the arm-like tip of the movable member. An engaging pulley; a coil spring that biases the movable member in a predetermined direction relative to the fixed member; and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member. An automatic tensioner for maintaining the belt tension moderately, and as the damper member, an annular space formed by a fixed member and a movable member is filled with a sliding member, and further, the sliding member and the movable member are Viscous fluid is sealed in the gap formed between the sliding member, the sliding member becomes a bearing, and the viscous fluid has a shear viscous resistance force that resists the rotation of the movable member and exhibits a large damping force. .

  The invention according to claim 8 of the present application is an autotensioner in which a fluid reservoir portion in which viscous fluid is sealed is provided in at least one end region of the annular vacancy, thereby filling the interface between the sliding member and the movable member. The made viscous fluid becomes difficult to flow to other regions and stays at that position, and the damper effect can be maintained for a long time.

  In the invention according to claim 9, the fixing member fixed to the vehicle body, the movable member of the arm-like structure rotatably supported by the fixing member, and the belt provided at the arm-like tip of the movable member. An engaging pulley; a coil spring that biases the movable member in a predetermined direction relative to the fixed member; and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member. An auto tensioner for maintaining the tension of the belt moderately, wherein the fixed member and the movable member are formed with a plurality of cylindrical walls and a cylindrical groove with the pivot axis of the movable member as a central axis. The wall is fitted into the cylindrical groove of the movable member, the viscous fluid is sealed in the communicating gap formed between them, and the sliding member is interposed in the tapered gap formed between the fixed member and the movable member. The viscous fluid. It can be exhibited efficiently damping force by applying a large shearing viscous resistance force than against rotation of the movable member the area of entrance is increased to.

In the invention of claim 10 of the present application, silicone oil is used as the viscous fluid, and the autotensioner exhibits a large shear viscous resistance.

  In the invention according to claim 11 of the present application, the viscosity of the silicone oil is in an auto tensioner having 500,000 to 1,200,000 centistokes at 25 ° C.

  In the autotensioner of the present invention, the film-like viscous fluid interposed in the gap between the movable member and the fixed member exhibits an excellent shear viscosity resistance force and has a large damping force, and the number of parts is reduced. Further, by changing the thickness of the viscous fluid sealed in the annular vacancy, the shear viscous resistance force that resists the rotation of the movable member can be adjusted. In addition, the viscous fluid reservoir groove at the boundary between the annular vacant chamber and the sealing material temporarily stores the viscous fluid, thereby eliminating the leakage of the viscous fluid from the sealing material and maintaining the damper effect for a long time. be able to.

  Since the communicating groove of the viscous fluid exists on the inner wall surface of at least one of the fixed member and the movable member forming the annular vacant space, the flow of the viscous fluid can be regulated to prevent the generation of turbulence, and It is possible to prevent air from remaining in the gap between the movable member and the fixed member, and to generate a uniform viscous resistance between the circumferential surface of the annular cavity and the viscous fluid. Further, when the annular vacancy is arranged on the outer side from the position of the coil spring, a large damping force can be generated.

  A configuration in which a sliding member is filled in an annular space formed by a fixed member and a movable member as a damper member, and a viscous fluid is sealed in a gap partially formed between the sliding member and the movable member Thus, the sliding member becomes a bearing, the movable member is stably installed on the fixed member, and the viscous fluid has a shear viscous resistance force that resists the rotation of the movable member, and effectively provides a damping force. Demonstrate.

  In addition, by providing a fluid reservoir that encloses the viscous fluid, the viscous fluid filled in the gap between the sliding member and the movable member is less likely to flow to other areas and stays at that position, thereby prolonging the damper effect. Can be maintained for hours. In particular, when a silicone oil having a viscosity of 500,000 to 1,200,000 centistokes at 25 ° C. is used as the viscous fluid, a large shear viscosity resistance is exhibited. Furthermore, if the area in which the viscous fluid is enclosed is increased, a large shear viscous resistance force against the rotation of the movable member is provided, and the damping force is efficiently exhibited.

Example 1
FIG. 1 is a schematic explanatory view of an example of an auto tensioner according to the present invention. The auto tensioner 1 fixes a fixed member 3 that is a bracket fixed to a fixed body (not shown) such as an automobile, a movable member 2 that is an arm rotatably supported by the fixed member 3, and the movable member 2. A coil spring 4 that biases toward the member 3 side, and a damper member 5 that is interposed between the movable member 2 and the fixed member 3 and attenuates and converges the swing of the movable member 2 are provided.

  In the movable member 2, a pulley 7 that is engaged with a belt is fixed to a shaft portion 8 that is rotatably supported via a bearing 9. The movable member 2 is urged to rotate to one side by a coil spring 4, whereby the outer peripheral surface of the pulley 7 is applied to a transmission belt 25 such as a V-ribbed belt for transmitting the rotation of the crankshaft of the engine to the alternator. The belt 25 is configured to abut and apply an appropriate tension to the belt 25.

  The movable member 2 and the fixed member 3 are made of aluminum or aluminum alloy casting (die casting), and the structural strength of the auto tensioner is increased to reduce the weight.

  The damper member 5 is disposed on the outer side of the coil spring 4, that is, at a position away from the turning shaft 11, and generates a damping force by a large torque. The coil spring 4 is accommodated in an annular spring accommodating portion 10 formed on the fixed member 3, and one end is locked to the inner wall of the fixed member 3 and the other end is locked to the inner wall of the movable member 2. 3 is a tension coil spring that pulls 3 together.

The damper member 5 encloses a viscous fluid 14 in an annular space 13 formed in the gap between the movable member 2 and the fixed member 3. The film thickness of the viscous fluid 14 is 0.05 to 2 mm, preferably about 0.1 to 1 mm. Further, bearings made of a sealing material 15 such as an O-ring and a solid lubricant are provided at both ends of the annular cavity 13. 16 is disposed to seal the annular space 13. The bearing 16 stably installs the movable member 2 on the fixed member 3. When the movable member 2 rotates, the viscous fluid 14 gives a shear viscous resistance force that resists the rotation of the movable member 2, and can generate an excellent damping force. If the thickness of the viscous fluid 14 is less than 0.05 mm, the characteristics of the viscous fluid disappear and shear viscous resistance cannot be obtained. On the other hand, if the thickness exceeds 2 mm, the shear viscous resistance decreases and the damping force decreases.
Of course, in the present embodiment, the annular vacant chamber 13 can be separated into a plurality of pieces, and the viscous fluid 14 can be enclosed therein.

  The viscous fluid 14 is, for example, silicone oil, and has a high viscosity of 500,000 to 1,200,000 centistokes at 25 ° C., and has a stable viscosity against heat change, and has a large shear viscosity resistance. Is obtained. Specifically modified with polydimethylsiloxane, polymethylphenylsiloxane, olefin-modified silicone, amino-modified silicone, carboxyl-modified silicone, α-methylstyrene-modified silicone, polyether-modified silicone modified with polyerylene glycol or polypropylene glycol, etc. It contains a siloxane bond.

In the auto tensioner 1, the pulley 7 pulls the belt 25 with the tension F by the spring force F ₀ (arrow in FIG. 2) of the coil spring 4, but the spring force F ₀ and the belt tension F are maintained in a balanced state. . When the belt stretches and its tension F decreases, the movable member 2 rotates. At this time, since the viscous fluid 14 provides a shear viscous resistance force that resists the rotation of the movable member 2, the belt tension is automatically adjusted. And the swinging of the movable member 2 is smoothly attenuated and converged.

Example 2
In the fixing member 3, for example, as shown in FIG. 3, a communication groove 18 for the viscous fluid 14 is provided on the entire inner wall surface 17 that forms the annular cavity 13. The viscous fluid 14 flows in a predetermined direction without causing turbulent flow, thereby preventing air from being accumulated and generating a uniform viscous resistance between the circular wall surface 17 of the annular cavity 13 and the viscous fluid 14. To do. Further, a reservoir groove 19 for viscous fluid is provided in the vicinity of the boundary between both end portions of the circular wall surface 17 and the seal material 15, and the viscous fluid 14 is once accommodated in the reservoir groove 19 and then the seal material 15. Therefore, a large fluid pressure is not directly applied to the sealing material 15, no leakage of the viscous fluid 14 from the sealing material 15, and a damper effect can be maintained for a long time.

Example 3
In the auto tensioner 1 shown in FIG. 4, the fixed member 3, the movable member 2, the coil spring 4 that urges the movable member 2 in a predetermined direction with respect to the fixed member 3, and the fixed member 3, as shown in FIG. 1. A shaft portion 8 that is formed in a gap with the movable member 2 and includes a damper member 5 disposed on the outer side of the coil spring 4, and a pulley 7 that is engaged with the belt in the movable member 2 is rotatably supported via a bearing 9. It is fixed to.

  The damper member 5 seals the annular space 13 by enclosing a viscous fluid 14 in an annular space 13 formed between the fixed member 3 and the movable member 2 and providing sealing materials 15 at both ends. Since the outer wall surface 21 of the fixed member 3 and the inner wall surface 22 of the movable member 2 form a conical surface having a taper angle of 0.5 to 10 degrees with a small diameter from one end portion to the other end portion, the auto tensioner The gap between the fixed member 3 and the movable member 2 can be adjusted by adjusting the movement of the fixed member 3 and the movable member 2 during assembly of 1. The movable member 2 is stably attached to the fixed member 3 by providing the bearing 16.

Example 4
The auto tensioner 1 shown in FIG. 5 is basically the same as the structure of the auto tensioner shown in FIG. 1, but the damper member 5 is disposed in the inner direction of the coil spring 4. A viscous fluid 14 is sealed in an annular space 13 formed in the gap between the movable member 2 and the fixed member 3, and a sealing material 15 is provided at both ends to seal the annular space 13. The bearing 16 stably installs the movable member 2 on the fixed member 3. The coil spring 4 is accommodated in an annular spring accommodating portion 10 formed by the fixed member 3 and the movable member 2, and one end is locked to the inner wall of the fixed member 3 and the other end is locked to the outer wall of the movable member 2. 2 and the housing material 2 are tension coil springs that draw each other.

Example 5
The auto tensioner 1 shown in FIG. 6 includes a fixed member 3, a movable member 2, a coil spring 4 that urges the movable member 2 in a predetermined direction with respect to the fixed member 3, and the fixed member 3, as shown in FIG. A damper member 5 is formed in the gap with the movable member 2 and arranged in the inner direction of the coil spring 4, and a pulley 7 engaged with the belt is rotatably fixed to the movable member 2. The coil spring 4 is accommodated in an annular spring accommodating portion 10 formed by the fixed member 3 and the movable member 2, and one end is locked to the inner wall of the fixed member 3 and the other end is locked to the outer wall of the movable member 2. 2 and the housing material 2 are tension coil springs that draw each other.

  The damper member 5 includes a sliding member 24 and a viscous fluid 14. The sliding member 24 is filled in an annular vacant space 13 formed in the gap between the fixed member 3 and the movable member 2, and has a bearing function by contacting the inner wall surface of the fixed member 3 and the movable member 2. On the other hand, the viscous fluid 14 fills a ring-shaped groove 26 partially provided on the surface of the sliding member 24 and comes into contact with the movable member 2, and a shear viscous resistance force that resists the rotation of the movable member 2 acts to greatly attenuate the fluid. Can demonstrate power.

  Further, a closed space is formed by a sealing material 15 in an end region of the interface between the sliding member 24 and the movable member 2, that is, at least one end region of the annular vacant space 13, and the viscous fluid 14 is placed therein. An enclosed fluid reservoir 25 is provided. As a result, the viscous fluid 14 that fills the interface between the sliding member 24 and the movable member 2 does not easily enter another region and stays at that position, and maintains the damper effect for a long time. The movable member 2 is stably attached to the fixed member 3 by providing the bearing 16.

  The sliding member 24 used here is generally a synthetic resin having a relatively small friction coefficient, and among them, polyamides such as nylon 66, nylon 46, nylon 610, polyacetal, polyethersulfone, polyterolafluoroethylene, etc. used.

  In the present embodiment, there is no restriction on the region where the viscous fluid 14 is filled, but preferably it is about 50 to 80% with respect to the surface area of the sliding member 24. Further, the viscous fluid 14 does not need to be filled in the annular groove 26 provided on the surface of the sliding member 24, and can be changed so as to enter the annular groove 26 provided on the outer surface of the movable member 2.

Example 6
The auto tensioner 1 shown in FIG. 7 includes a fixed member 3 and a movable member 2 that is swingably supported by the fixed member 3. A pulley 7 is rotatably supported at the tip of the movable member 2. The movable member 2 is urged to rotate to one side by a coil spring 4 so that the outer peripheral surface of the pulley 7 has a V-ribbed belt (rotating body) (not shown) for transmitting the rotation of the crankshaft of the engine to the alternator. A belt for driving), and an appropriate tension is applied to the belt.

  The fixed member 3 has a plurality of ring-shaped cylindrical walls 30a (two in the figure) and cylindrical grooves 31a (two in the figure) projecting toward the movable member 2 alternately with the pivot shaft 11 of the movable member 2 as a central axis. The movable member 2 also has a plurality of cylindrical walls 30b and a cylindrical groove 31b that protrude toward the fixed member 3, and the cylindrical wall 30a of the fixed member 3 is formed into the cylindrical groove of the movable member 2. The above-mentioned viscous fluid 14 is sealed in a communicating state in the gap 32 formed between them so as to be fitted to 31b, and the sealing material 33 prevents the viscous fluid 14 from leaking. Further, a plug member 35 is installed in the viscous fluid relief port 34 to close the relief port 34. The area in which the viscous fluid 14 is enclosed becomes large and has a large shear viscosity resistance force that resists the rotation of the movable member 2.

  The movable member 2 includes an annular wall 35 that protrudes toward the fixed member 3, while the fixed member 3 includes a first annular wall 37 and a second annular wall 38 that protrude toward the movable member 2. A tapered cylindrical sliding member 39 is interposed between the outer peripheral surface of the annular wall 36 and the inner peripheral surface of the second annular wall 38. The sliding member 39 is made of a synthetic resin having a relatively small friction coefficient, such as nylon 66, nylon 46, polyacetal, and the like, and the movable member 2 is rotatable with respect to the fixed member 3 through the sliding member 39. It is supported by.

  Outside the second annular wall 38, the movable member 2 and the fixed member 3 are formed with annular spring accommodating portions 40 and 41 that face each other. A coil spring 4 is installed inside the spring accommodating portions 40 and 41. One end of the spring wire of the coil spring 4 is fixed to the fixed member 3 and the other end is fixed to the movable member 2. The coil spring 4 applies an urging force for urging the movable member 2 to one side with respect to the fixed member 3, and at the same time, pulls in the axial direction in a direction in which the fixed member 3 and the movable member 2 are brought close to each other. Power is applied. As a result, between the tapered outer peripheral surface of the annular wall 36 and the sliding member 39, and between the tapered inner peripheral surface of the second annular wall 38 and the sliding member 39, a predetermined surface pressure is obtained. Is generated. Therefore, when the movable member 2 rotates relative to the fixed member 3, the frictional resistance generated between the sliding member 39 and each tapered surface resists it.

  With the above configuration, when the movable member 2 rotates relative to the fixed member 3 due to vibration or impact transmitted from the pulley 7 to the movable member 2, the clearance 32 having the above-described area increased. Since the shear viscous resistance of the viscous fluid 14 sealed in and the frictional resistance of the sliding member 39 resist, a large damper effect can be exhibited, and such vibration and impact can be appropriately damped and absorbed.

  The auto tensioner according to the present invention can be widely used as a device that automatically keeps the tension of an auxiliary machine driving belt mounted on a multi-axis drive device such as an automobile engine automatically and appropriately.

It is sectional drawing of the auto tensioner which concerns on Example 1 of this invention. It is the figure which looked at FIG. 1 from the AA direction. The state of the outer peripheral surface of the fixing member used with the auto tensioner which concerns on Example 2 of this invention is shown. It is sectional drawing of the auto tensioner which concerns on Example 3 of this invention. It is sectional drawing of the auto tensioner which concerns on Example 4 of this invention. It is sectional drawing of the auto tensioner which concerns on Example 5 of this invention. It is sectional drawing of the auto tensioner which concerns on Example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Autotensioner 2 Movable member 3 Fixed member 4 Coil spring 5 Damper member 6 Sliding part 7 Pulley 10 Space part 11 Swivel shaft 13 Annular empty space 14 Viscous fluid 15 Sealing material 24 Sliding member 25 Fluid reservoir part 30a Cylindrical wall 30b Cylinder Wall 31a cylindrical groove 31b cylindrical groove

Claims (11)

  A fixed member fixed to a vehicle body, a movable member of an arm-like structure that is rotatably supported by the fixed member, a pulley that is provided at an arm-like tip of the movable member and engages with a belt, and a movable member In order to keep the tension of the belt appropriately provided with a coil spring that urges the fixed member in a predetermined direction and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member The above-described auto tensioner is characterized in that a membrane-like viscous fluid is interposed as a damper member in the gap between the movable member and the fixed member, and a shear viscous resistance force of the viscous fluid that resists the rotation of the movable member is applied. Auto tensioner.   The auto tensioner according to claim 1, wherein the viscous fluid is sealed in an annular space formed between the fixed member and the movable member, and a shear viscous resistance force of the viscous fluid that resists rotation of the movable member is applied.   The auto tensioner according to claim 2, wherein a reservoir groove for the viscous fluid is provided at a boundary portion between the annular vacancy and the sealing material.   The autotensioner according to claim 2 or 3, wherein a communicating groove for the viscous fluid is provided on at least one inner wall surface of the fixed member and the movable member forming the annular vacancy.   The auto tensioner according to any one of claims 2 to 4, wherein the annular vacancy is disposed on the outer side from the position of the coil spring.   The auto tensioner according to any one of claims 2 to 5, wherein the annular vacancy is formed in a conical shape.   A fixed member fixed to a vehicle body, a movable member of an arm-like structure that is rotatably supported by the fixed member, a pulley that is provided at an arm-like tip of the movable member and engages with a belt, and a movable member In order to keep the tension of the belt appropriately provided with a coil spring that urges the fixed member in a predetermined direction and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member As the damper member, the annular member formed by the fixed member and the movable member is filled with the sliding member, and the gap formed between the sliding member and the movable member is viscous. Auto tensioner characterized by enclosing fluid.   The auto tensioner according to claim 7, wherein a fluid reservoir in which a viscous fluid is sealed is provided in at least one end region of the annular vacancy.   A fixed member fixed to a vehicle body, a movable member of an arm-like structure that is rotatably supported by the fixed member, a pulley that is provided at an arm-like tip of the movable member and engages with a belt, and a movable member In order to keep the tension of the belt appropriately provided with a coil spring that urges the fixed member in a predetermined direction and a damper member that is interposed between the movable member and the fixed member to attenuate and converge the swing of the movable member A plurality of cylindrical walls and a cylindrical groove with the pivot axis of the movable member as a central axis are formed in the fixed member and the movable member, and the cylindrical wall of the fixed member is formed into the cylindrical groove of the movable member. An auto-tensioner characterized in that a viscous fluid is sealed in a communicating gap formed between them and a sliding member is interposed in a tapered gap formed between a fixed member and a movable member.   The auto tensioner according to any one of claims 1 to 9, wherein the viscous fluid is silicone oil. The autotensioner according to claim 10, wherein the viscosity of the silicone oil is 500,000 to 1,200,000 centistokes at 25 ° C.

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