JP3257252B2 - Damper device for auto tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A damper device for an automatic tensioner according to the present invention is a belt for driving an auxiliary device such as a timing belt of an automobile engine or an alternator or a compressor (hereinafter referred to simply as "belt"). ) Is incorporated into an auto tensioner that applies an appropriate tension, and is used to suppress the vibration of the belt.

[0002]

2. Description of the Related Art In order to drive a camshaft of an OHC or DOHC engine in synchronization with a crankshaft, a driving device using a belt 1 as shown in FIG. 2 is widely used. In FIG. 2, reference numeral 2 denotes a driving pulley which is driven to rotate by a crankshaft of an engine, 3 denotes a driven pulley fixed to an end of a camshaft, and 4 and 4 guide a belt 1 or a water pump. Guide pulley or driven pulley for driving auxiliary equipment such as
This is a pulley that forms an auto tensioner for applying an appropriate tension to the pulley.

The pulley 5 is pivotally supported by a swing member 7 that swings about a pivot 6. A spring 9 is provided at an end of the bracket 8 fixed to the swing member 7,
The spring 9 presses the pulley 5 elastically toward the belt 1. The tension of the belt 1 is always kept constant irrespective of the dimensional change of the belt 1 and the like due to the temperature change and the like and the vibration caused by the operation of the engine.

[0004] By the way, a belt 1 is used for an auto tensioner.
In addition to the function of applying tension to the belt 1, a function of holding down the belt 1 is required. That is, in the camshaft driving device shown in FIG. 2, when the driving pulley 2 rotates, a portion of the belt 1 located between the pulleys 2 to 5
It tends to vibrate so as to swing in a direction perpendicular to the traveling direction. If this deflection is allowed as it is, the amplitude of the deflection increases (vibration grows), abnormal vibration occurs in the driving portion driven by the belt 1, or in the case of a toothed belt, so-called tooth jump occurs. Cause problems.

For this reason, conventionally, for example, Japanese Patent Application Laid-Open No. 58-65
As described in JP-A-357-357 and JP-A-63-180759, a damper device is incorporated in an auto tensioner, and the belt 1 is suppressed by the damper device. In order to more reliably prevent the belt 1 from loosening, when the belt 1 is slack, the pulley 5 is quickly followed, and when the belt 1 is taut, the pulley 5 is not retracted. 1 is also disclosed in, for example, JP-A-63-167163, JP-A-2-72252, and 2-80839.
Gazette, JP-A-3-24346, and JP-A-2-1684
No. 6, No. 2-98243, No. 4-39349
As described in Japanese Unexamined Patent Publication (Kokai) No. HEI 10-301, it is conventionally known.

The auto-tensioners described in these publications provide a one-way clutch between a viscous damper and a swinging member (Japanese Patent Application Laid-Open No. 63-167163), or provide a ratchet mechanism (Japanese Patent Application Laid-Open No. Hei 2-167163). Japanese Unexamined Patent Publication (Kokai) No. 2-80839, Japanese Utility Model Laid-Open Publication No. 2-16846) and a damper device which incorporates a check valve and functions only in one direction.
No. 252, No. 3-24346, Japanese Utility Model Application Laid-Open No. 2-9
No. 8243), a damper device provided with an inclined surface for facilitating the flow of a viscous liquid in only one direction or the like (Japanese Utility Model Application Laid-Open No.
No. 9349). Further, Japanese Unexamined Patent Application Publication No. 62-274
No. 143, Japanese Utility Model Publication No. 60-52458, etc.
It describes a structure in which an oscillating member and a damper device are separated from each other, and each is separately attached to a front surface of a cylinder block or the like of an engine to form an auto tensioner.

[0007] Among the prior arts constructed as described above, in the auto-tensioner described in JP-A-58-65357 and JP-A-63-180759, the pulley can only be displaced slowly in any direction. Therefore, when the belt is slackened, the pulley cannot follow the slack, and the tension of the belt may temporarily decrease. Also, the above-mentioned JP-A-63-
167163, JP-A-2-72252, JP-A-2-80839, JP-A-3-24346, JP-A-2-16846, JP-A-2-98243, JP-A-4-39349 and the like. In the case of the auto-tensioner, the one-way clutch fretting wears,
Inadequate durability (Japanese Unexamined Patent Publication No. 63-167163)
JP-A-2-72252, JP-A-2-8083, and the manufacturing cost is high because the internal structure is complicated and manufacturing is difficult.
No. 9, JP-A-3-24346, and JP-A-2-168.
No. 46, No. 2-98243), the characteristics are liable to change with time due to wear of the parts, and even if the belt becomes slack, the belt is slightly affected by the viscous liquid. Not available (Japanese Unexamined Patent Publication No. 2-72252)
Gazette, JP-A-3-24346, and JP-A-2-9824
No. 3, No. 4-39349). Further, Japanese Unexamined Patent Publication (Kokai) No. 62-274143, Japanese Utility Model Application Laid-Open No. 60-52458.
In the case of the auto-tensioner described in Japanese Patent Application Laid-Open Publication No. H10-209, the follow-up performance is poor when the installation space is large or the belt tension is suddenly reduced.

[0008]

Prior art as prior art of the present invention In view of the above circumstances, the present inventor has previously invented an auto tensioner as shown in FIGS. 3 and 4 (Japanese Utility Model Application No. 4-67543 (FIG. 3)). No. 5-29569 (FIG. 4)).

The auto-tensioner shown in FIG. 3 rotatably supports a base end portion of a swing member 12 around a fixed shaft 11 provided on a fixed member 10, and a distal end of the swing member 12. The part is provided with a pivot 13 parallel to the fixed shaft 11. The pulley 5 is rotatably supported around the pivot 13, and the belt 1 to be tensioned is stretched over the pulley 5. Around the fixed shaft 11,
A coil portion 15 of a torsion coil spring 14, which is a tension applying spring that applies an elastic force in the direction of pressing the pulley 5 toward the belt 1, is provided on the swing member 12. Further, a pair of locking portions 16 provided at both ends of the torsion coil spring 14 are provided.
a and 16b respectively provide the elasticity in the direction of pressing the pulley 5 toward the belt 1 to the rocking member 12 by being locked to the fixing member 10 and the rocking member 12.

A damper device 19 extends between a fixed arm 17 provided on the fixed member 10 and a swing arm 18 provided on the swing member 12. That is, in the case of the illustrated structure, the base end of the cylinder cylinder 20 is fixed to the tip of the fixed arm 17, and the plunger 22 is fixed to the lower surface of the receiving block 21 fixed to the tip of the swing arm 18. Butts.

On the other hand, in the auto tensioner shown in FIG. 4, the fixing member 10 is omitted from the structure shown in FIG. A damper device 19 is attached to the tip of the swinging arm 18.
And a projecting portion (not shown) formed at a lower end of the damper device 19 from a lower surface of the swing arm 18 to a fixed portion such as a front surface of a cylinder block of the engine.
And can be freely hit. The locking portion 16a of the torsion coil spring 14 is locked to the fixed portion.

In any case of the auto tensioner having any structure, the damper device 19 is configured as shown in FIG. 5 or FIG. The cylinder cylinder 24 in which a viscous liquid 23 such as silicon oil is sealed has a bottomed cylindrical shape with an open upper end and a closed lower end. This cylinder tube 24
A piston 25 is fitted in the lower half of the inside so as to be able to move up and down. Note that a small gap exists between the inner peripheral surface of the cylinder tube 24 and the outer peripheral surface of the piston 25. Above piston 2
The viscous liquid 23 existing on the upper side and the lower side of 5 slowly flows through the minute gap. Also, the piston 25
An urging spring 26, which is a compression coil spring, is provided between the lower surface of the cylinder cylinder 24 and the upper surface of the bottom of the cylinder tube 24 to urge the piston 25 upward. Further, the cylinder cylinder 24
The base 28 of the plunger 22 is fitted in the upper half of the inside of the upper part so as to be able to move up and down. A seal ring 29 is provided between the inner peripheral surface of the cylinder tube 24 and the outer peripheral surface of the base 28 to maintain liquid tightness between the two peripheral surfaces. The piston 25
A plurality of cutouts 30, 30 are formed in the upper end surface of the base member 28. Through the cutouts 30, 30, the inner space 31 existing inside the butted portion of the base 28 and the piston 25 communicates with the minute gap. I have.

On the other hand, the partition 3 constituting the piston 25
A through hole 33 is formed at the center of the piston 2 so that the piston 25
And a passage connecting the upper and lower sides. A check valve 3 for opening and closing the through hole 33 is provided in a lower portion of the partition wall 32.
4 are provided. The check valve 34 elastically presses the ball 39 toward the lower end opening of the through hole 33 by the elastic force of the spring 38, and the piston 25 is displaced upward by the elastic force of the urging spring 26. Has the function to open only when.

Further, the damper device 1 of the first example shown in FIG.
In the case of No. 9, the outer diameter of the first half 27 of the plunger 22 is made sufficiently smaller than the inner diameter of the cylinder tube 24 so that the outer peripheral surface of the first half 27 and the upper inner peripheral surface of the cylinder tube 24 are formed. The viscous liquid 23 is also injected into the lower half of the upper space 35 between them. The viscous liquid 23 can be freely circulated between the upper space 35 and the inner space 31 through communication holes 36 provided in a continuous portion between the base 28 and the first half 27. A seal ring 37 is provided between the inner peripheral surface of the upper end portion of the cylinder cylinder 24 and the outer peripheral surface of the first half portion 27 to close the upper end opening of the upper space 35.

On the other hand, the damper device 1 of the second example shown in FIG.
In the case of 9, instead of making the first half 27a relatively large in diameter and increasing the internal volume of the first half 27a, communication holes 36, 36 (FIG. 5) for passing the inside and outside of the plunger 22 are omitted. . When the damper device 19 shown in FIG. 6 is incorporated in the auto-tensioner shown in FIG. 4, in the illustrated example, the cylinder tube 24 is projected from the lower surface of the swing arm 18 and the lower portion of the cylinder tube 24 is The end surface can be freely abutted on the upper surface of a protrusion formed on a fixed portion such as the front surface of a cylinder block of the engine. 6A shows a contracted state of the damper device, and FIG. 6B shows an extended state of the damper device.

The auto-tensioner of the present invention, which incorporates the damper device 19 constructed as described above, and which is constructed as described above, for example, is incorporated in an engine as shown in FIG. Appropriate tension is applied to 1. Although FIG. 7 shows an example using the auto tensioner shown in FIG. 3, it is similarly incorporated in the auto tensioner shown in FIG. 4, and an appropriate tension is applied to the belt 1. In the use state of the auto tensioner as shown in FIG. 7, the swing member 12 swings based on the elasticity of the torsion coil spring 14, and the pivot 13 (FIG. Pulley 5 rotatably supported in 4)
Is elastically pressed toward the belt 1. When the pulley 5 is pressed against the belt 1, the swing of the swing member 12 is limited. In this state, it is provided between the fixed arm 17 (in the case of the structure of FIG. 3) or a protrusion formed in a fixed portion such as a cylinder block (in the case of the structure of FIG. 4) and the swing arm 18. The damper device 19 is in a state of being stretched between the fixed-side arm piece 17 or the projection and the swing-side arm piece 18 based on the elasticity of the urging spring 26.

When the belt 1 is loosened from this state, the swing member 12 swings based on the elasticity of the torsion coil spring 14, and causes the pulley 5 to follow the movement of the belt 1. At this time, since the displacement of the plunger 22 constituting the damper device 19 is slightly delayed, the tip of the plunger 22 and the lower surface of the receiving block 21 (in the case of the structure shown in FIG. 3) or the lower surface of the cylinder tube 24 And the upper surface of the protrusion (in the case of the structure shown in FIG. 4) are separated from each other. Therefore, belt 1
Is loose, the damper device 19 does not cause any resistance to rotating the swinging member 12 so that the pulley 5 follows the movement of the belt 1. As a result, the pulley 5 can quickly follow the movement of the belt 1 to prevent the tension of the belt 1 from decreasing. The entire length of the damper device 19 extends slightly later than the movement of the swing member 12 due to the elasticity of the urging spring 26.

As described above, when the damper device 19 is extended based on the elasticity of the urging spring 26, the check valve 34 is opened. That is, the ball 39 descends against the elasticity of the spring 38, and opens the lower end opening of the through hole 33 formed in the partition wall 32. As a result, the viscous liquid 2 moves from the upper side to the lower side of the partition 32.
3, the piston 25 and the plunger 22 are relatively quickly raised, and after a very short time, the damper device 19 is moved to the fixed side arm piece 17 or the projection and the swinging side arm. Stretch between the pieces 18.

Conversely, when the tension of the belt 1 increases, the swing member 12 tends to rotate against the elasticity of the torsion coil spring 14. In this state, the swing-side arm piece 18 presses the damper device 19 in the compression direction. Accordingly, in this case, in order to rotate the swing member 12, the plunger 22 and the piston 25 are connected to the urging spring 26.
Must be pushed into the cylinder 24 against the elasticity of the cylinder. At this time, the check valve 34 remains closed, so that the viscous liquid 23 existing below the piston 25 is
Must be moved through a minute gap existing between the inner peripheral surface of the cylinder tube 24 and the outer peripheral surface of the piston 25. Since the amount of the viscous liquid 23 flowing through the minute gap is limited, the displacement of the piston 25 and the plunger 22 is performed only slowly. As a result, the displacement of the pulley 5 supported by the swing member 12 is also performed only slowly by the action of the damper device 19, and the belt 1 is suppressed by the pulley 5, and the vibration of the belt 1 grows. You won't have to.

[0020]

However, in the case of a damper device for an auto tensioner configured as described above and acting as described above in a state where the damper device is incorporated in the auto tensioner,
When the tension of the belt 1 suddenly and greatly decreases from the state where the belt 1 becomes high, there is a possibility that air enters into the lower side of the piston 25, and if it enters, the damper device 19
Performance will be reduced. Such a phenomenon that the increased tension rapidly decreases often occurs when the engine is started or stopped. When such a phenomenon occurs, the entire length of the damper device 19 is reduced from the contracted state to the biasing spring 2.
It expands rapidly based on the elasticity of 6.

For example, in the case of the damper device 19 having a structure as shown in FIG.
The damper device 19 once contracted as shown in FIG.
Extend through the states shown in FIGS. 8B to 8D to the state shown in FIG. That is, when the contracted damper device 19 expands as shown in FIG.
As shown in FIG. 7, the check valve 34 opens, and the plunger 22 and the piston 25 start to rise. Note that the shape of the damper device 19 shown in FIG. 8 is slightly different from the shape of the damper device 19 shown in FIG. 5, but the basic functions are the same.

As the piston 25 rises, the upper space 35
The viscous liquid 23 flows into the inner space 31 through the communication holes 36, 36. At this time, as shown in FIG.
The air 40 existing in the upper space 35 is
6 and 36 enter the inside space 31. And
When the rising speed of the piston 25 is high, as shown in FIG. 3D, air entering from the communication holes 36, 36 traverses the inner space 31, passes through the through hole 33 at the center of the partition 32, and It reaches below 32.

A part of the air 40 which has reached the lower side of the partition wall 32 in this way stops the rise of the piston 25,
After the check valve 34 is closed, as shown in FIGS. 8E and 10, the check valve 34 remains as it is under the partition 32.

Also, in the case of the damper device 19 having the structure shown in FIG. 6, from the contracted state shown in FIG. 9A to the expanded state shown in FIG. During the displacement through the state (E), the air 40 enters under the partition 32.

The air 40 that has entered the lower side of the partition 32 in this way remains as it is under the partition 32, as shown in FIG. However, since the air 40 is a compressible fluid, unlike the viscous liquid 23, which is an incompressible fluid, it functions to elastically expand and contract the entire length of the damper device 19, and deteriorates the performance of the damper device 19. I will. The damper device for an auto tensioner according to the present invention is designed to prevent air from entering the lower side of the piston 25 in order to prevent performance degradation due to such causes.

[0026]

SUMMARY OF THE INVENTION A damper device for an auto tensioner according to the present invention comprises: a cylinder cylinder having a viscous liquid sealed therein; a piston fitted inside the cylinder cylinder so as to be displaceable in an axial direction; An urging spring, which is provided between the piston and the cylinder cylinder and urges the piston in one direction, and an amount of protrusion from the cylinder cylinder with the displacement of the piston based on the elasticity of the urging spring. An increasing plunger, a passage communicating between both end faces of the piston in the axial direction, and a check valve that opens only when the piston is displaced based on the elasticity of the biasing spring.

In particular, in the damper device for an automatic tensioner according to the present invention, the passage includes a through hole formed in a center portion of the piston, and a top surface of the piston around an upper end opening of the through hole. The portion is a mortar-shaped inclined surface that goes downward as approaching the through hole.

[0028]

The operation of the damper device for an auto tensioner according to the present invention configured as described above, in which the displacement of the swinging member supporting the pulley is limited in order to suppress the belt vibration in a state where the damper device is incorporated in the auto tensioner. In itself, it is the same as in the case of the above-described damper device incorporated in the auto tensioner of the invention.

In particular, in the damper device for an auto tensioner of the present invention, the viscous liquid existing on the upper side of the piston flows smoothly toward the through hole while being guided on the sloping inclined surface. Therefore, even when the damper device suddenly extends,
It becomes difficult for air existing above the viscous liquid to enter the inside of the plunger through the communication hole. As a result, there is no possibility that air enters under the piston, and the performance of the damper device can be prevented from being reduced by air.

[0030]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. The left half shows the most contracted state and the right half shows the most expanded state. Inside the bottomed cylindrical cylinder 24 having an open upper end, silicon oil, synthetic oil,
A viscous liquid 23 such as high-purity mineral oil or the like is sealed, and a piston 25 is fitted so as to be movable up and down. An urging spring 26 is provided between the lower surface of the piston 25 and the upper surface of the bottom of the cylinder cylinder 24 to give the piston 25 elasticity in the upward direction.

On the other hand, a plunger 22a is provided above the piston 25. The amount of protrusion of the plunger 22a from the cylinder tube 24 increases with the rise of the piston 25 based on the elasticity of the urging spring 26. Further, a through hole 33 is formed in the center of the partition wall 32 of the piston 25, and a passage connecting the upper side and the lower side of the piston 25 (both axial end surfaces) is formed. Further, the partition 32
Is provided with a check valve 34 composed of a spring 38 and a ball 39 at the lower part. The check valve 34 is connected to the piston 2
It opens only when 5 rises based on the elasticity of the urging spring 26.

On the upper surface of the piston 25, the through hole 33
Is formed as a mortar-shaped inclined surface 41 that goes downward as it approaches the through-hole 33. This slope 4
As shown in the figure, the inclination angle of 1 is relatively steep (for example, with respect to a horizontal plane) so that the viscous liquid 23 existing above the through-hole 33 flows smoothly toward the through-hole 33 when the piston 25 rises. 60 degrees or more).

In the lower half of the plunger 22a,
Cylindrical portion 42 slidingly contacting the inner peripheral surface of cylinder cylinder 24
A rod-shaped portion 43 having an outer diameter sufficiently smaller than the inner diameter of the cylinder tube 24 is formed in the upper half. This rod-shaped portion 43 is a solid body similar to that of FIG. 8, different from the prior invention structure shown in FIGS. Then, the cylindrical portion 42 and the rod-shaped portion 4
Communication holes 36 and 36 are provided in a continuous portion of the upper space 3 so that the upper space 35 communicates with the inner space 31.

The upper end opening of the cylinder tube 24 is closed by a boot 44 made of a flexible material. The boot 44 is formed by combining a metal core 45 made of a metal plate such as mild steel in an annular shape and an elastic material 46.
The core metal 45 has a crank-shaped cross section in which a large-diameter base end 47 and a small-diameter distal end 48 are connected by a step 49. Such a core metal 45 is formed by externally fitting the base end portion 47 to the upper end portion of the cylinder tube 24 until the lower surface of the step portion 49 abuts against the upper end surface of the cylinder tube 24. It is supported and fixed to the upper end.

On the other hand, the elastic member 46 is formed in a cylindrical shape as a whole, and the base end portion of the elastic member 46 is baked or inserted into the distal end portion 4 of the metal core 45 by an insert or the like.
8. The thick locking portion 51 formed at the distal end of the elastic member 46 is connected to the plunger 22a.
Are engaged with locking grooves 52 formed on the outer peripheral surface of the rod-shaped portion 43. Therefore, the upper end opening of the cylinder cylinder 24 is
The boot 44 is closed. The elastic material 46 constituting the boot 44 is made of, for example, chlorinated olefin rubber.
Use a material that has sufficient durability against fatigue due to expansion and contraction and has excellent temperature characteristics (cold resistance and heat resistance).

[0036] Further, the inner diameter R ₄₈ of the tip 48 of the core metal 45 is made smaller (R ₄₈ <R ₂₄₎ than the inner diameter R ₂₄ of the cylinder barrel 24. At the same time, the tip 4
The elastic material 46 covers a portion of the bent corner portion where the lower end portion 8 and the inner peripheral end portion of the step portion 49 are continuous with each other and the portion facing the shoulder portion of the plunger 22a. Therefore, when the plunger 22a is lifted, the shoulder is moved to the elastic member 46.
To prevent the plunger 22a from slipping out of the cylinder tube 24. Since the lower end edge portion of the base end portion 47 of the cored bar 45 is caulked to the groove 50 formed on the upper outer peripheral surface of the cylinder tube 24, the cored bar 45 may not drop from the cylinder tube 24 carelessly. Absent.

With the damper device for an auto tensioner of the present invention constructed as described above incorporated in an auto tensioner as shown in FIG. 3 or FIG. The operation itself when limiting the displacement of the swinging member 12 supporting the same is the same as the case of the above-described damper device incorporated in the auto-tensioner of the prior invention.

In particular, according to the damper device for an auto-tensioner of the present invention, even when the piston 25 rises rapidly due to the rapid extension of the damper device 19, the air existing above the viscous liquid 23 causes the air above the viscous liquid 23 to pass through the partition wall 32. It is difficult to reach the inside of the through hole 33 formed at the center. That is, when the tension of the belt 1 suddenly fluctuates due to the start and stop of the engine and the total length of the damper device 19 is reduced from the state of being shortened based on the elasticity of the urging spring 26, the left half of FIG. The damper device 19 which has once contracted as shown in the section extends to the state shown in the right half of FIG. As described above, when the piston 25 rises rapidly so that the damper device 19 extends, the air existing in the upper space 35 pushes the liquid surface of the viscous liquid 23.

As described above, when the piston 25 ascends while the air presses the upper surface of the viscous liquid 23, if a large space exists around the upper end opening of the through hole 33 communicating vertically with the piston 25, The air easily reaches the through hole 33 while pushing the air 23 into this space. On the other hand, in the case of the damper device 19 of the present invention, the viscous liquid 23 existing above the piston 25 is smoothly guided to the through hole 33 based on the existence of the inclined surface 41, 3
3 becomes difficult for air to reach. In other words, air 40
Even when the liquid (see FIGS. 8 and 9) flows toward the through hole 33, the viscous liquid 23 pushed by the air 40 does not escape to the side and is pushed into the through hole 33 as it is. Therefore, even when the damper device is rapidly extended from the contracted state shown in the left half of FIG. 1 to the extended state shown in the right half of FIG. The above partition wall 3
It is difficult to reach the inside of the through hole 33 formed at the center of the second. As a result, there is no possibility that the air 40 enters under the piston 25, and the performance of the damper device can be prevented from being reduced by the air 40.

[0040]

The damper device for an auto tensioner according to the present invention is constructed and operates as described above. However, since the air can be reliably prevented from entering the lower side of the piston, the performance of the damper device is reduced by the air. There is no deterioration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a front view showing an example of a state of use of a conventionally known auto tensioner.

FIG. 3 is a front view showing a first example of an auto tensioner according to the invention.

FIG. 4 is a front view showing the second example.

FIG. 5 is a longitudinal sectional view showing a first example of a damper device incorporated in the auto tensioner according to the prior invention.

FIG. 6 is a longitudinal sectional view showing the second example in a contracted state and an extended state.

FIG. 7 shows a state of use of the auto-tensioner according to the invention.
The front view which shows an example.

FIG. 8 is a longitudinal sectional view showing the auto tensioner shown in FIG. 5 in a stroke order from a contracted state to an extended state.

FIG. 9 is a vertical cross-sectional view showing a sequence of steps from a contracted state to an extended state of the auto tensioner shown in FIG. 6;

FIG. 10 is a lower longitudinal sectional view of the damper device showing a state in which air has entered the lower side of the piston.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 belt 2 drive pulley 3 driven pulley 4 guide pulley or driven pulley 5 pulley 6 pivot 7 swing member 8 bracket 9 spring 10 fixing member 11 fixed shaft 12 swing member 13 pivot 14 torsion coil spring 15 coil portions 16a, 16b Stop portion 17 Fixed arm piece 18 Swing-side arm piece 19 Damper device 20 Cylinder cylinder 21 Receiving block 22, 22a Plunger 23 Viscous liquid 24 Cylinder cylinder 25 Piston 26 Urging spring 27, 27a First half 28 Base 29 Seal ring 30 Notch 31 Inner space 32 Partition wall 33 Through hole 34 Check valve 35 Upper space 36 Communication hole 37 Seal ring 38 Spring 39 Ball 40 Air 41 Inclined surface 42 Cylindrical part 43 Rod part 44 Boot 45 Core metal 46 Elastic material 47 Base End part 48 Tip part 49 Step part 50 Groove part 51 Part 52 engaging groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-115959 (JP, A) JP-A-4-99445 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 7/00-7/24 F16F 9/00-9/54

Claims (1)

(57) [Claims] 1. A cylinder cylinder in which a viscous liquid is sealed, a piston fitted in the cylinder cylinder so as to be displaceable in an axial direction, and a piston provided between the piston and the cylinder cylinder. Spring, which biases the piston in one direction, a plunger that increases the amount of protrusion from the cylinder cylinder with the displacement of the piston based on the elasticity of the biasing spring, and communicates with both axial end faces of the piston. And a check valve that opens only when the piston is displaced based on the elasticity of the biasing spring, the passage is formed at the center of the piston. An auto-tensioner dam including a through hole, wherein a portion of the upper surface of the piston surrounding the upper end opening of the through hole is a sloping inclined surface directed downward as approaching the through hole. Dumping device.