JPH0710595U - Damper device for auto tensioner - Google Patents

Abstract

(57) [Abstract] [Purpose] Even when a pressing force that is non-parallel to the central axis is applied to the upper end of the plunger 22a, the edge load is applied to the end of the outer peripheral surface of the cylindrical portion 41 and the piston 25. Prevent it from happening. [Structure] The upper and lower end portions of the outer peripheral surface of the cylindrical portion 41 and the piston 25 are crowned.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The damper device for an autotensioner according to the present invention is suitable for a timing belt of an automobile engine or a belt for driving an auxiliary machine such as an alternator or a compressor (hereinafter, these are simply referred to as a "belt"). Used to suppress the vibration of the belt by incorporating it into an auto tensioner that gives tension.

[0002]

[Prior art]

 Since a camshaft of an OHC or DOHC type engine is driven to rotate in synchronization with a crankshaft, a drive device using a belt 1 as shown in FIG. 3 is widely used. In FIG. 3, 2 is a drive pulley which is rotationally driven by the crankshaft of the engine, 3 is a driven pulley which is fixed to the end of the camshaft, 4 and 4 are for guiding the belt 1, or water. Guide pulleys or driven pulleys for driving auxiliary machines such as pumps and the like, and 5 are pulleys for giving proper tension to the belt 1.

The pulley 5 is pivotally supported by a swing member 7 that swings around a pivot 6. A spring 9 is provided at the end of the bracket 8 fixed to the swinging member 7, and the spring 5 elastically presses the pulley 5 toward the belt 1 so that the belt 1 and the like accompanying the temperature change are The tension of the belt 1 is always kept constant regardless of dimensional changes and vibrations caused by engine operation.

By the way, in addition to the function of applying tension to the belt 1, the automatic tensioner is required to have a function of holding down the belt 1. That is, in the camshaft drive device shown in FIG. 3, when the drive pulley 2 is rotated, a part of the belt 1 located between the pulleys 2 to 5 is a direction perpendicular to the traveling direction. In addition, there is a tendency to vibrate. If this vibration is allowed as it is, the amplitude of the vibration becomes large (vibration grows), abnormal vibration occurs in the drive part by the belt 1, or in the case of a toothed belt, so-called tooth skipping occurs. Etc. causes problems.

Therefore, conventionally, for example, as described in JP-A-58-65357 and JP-A-63-180759, a damper device is incorporated in an auto tensioner, and the belt 1 is mounted by the damper device. Something is being held down. In order to prevent the belt 1 from slackening more reliably, the pulley 5 is swiftly followed when the belt 1 is slackened, and when the belt 1 is strained, the pulley 5 is not retracted. An automatic tensioner that holds down the belt 1 is also disclosed in, for example, JP-A-63-167163, JP-A-2-72252, JP-A-2-80839, JP-A-3-2346, and JP-A-2-16846. , No. 2-98243, No. 4-39349, etc., are conventionally known.

The auto tensioner described in each of these publications is provided with a one-way clutch between the viscous damper and the oscillating member (Japanese Patent Laid-Open No. 63-167163) or a ratchet mechanism (Japanese Laid-Open Patent Publication No. HEI-2). No. 80839, Japanese Utility Model Laid-Open No. 2-16846), a checker valve is incorporated to provide a damper device that functions only in one direction (Japanese Patent Laid-Open No. 2-72252, No. 3-24346, and Japanese Utility Model Laid-Open No. 2-2). No. 98243), a damper device having an inclined surface for facilitating the flow of the viscous liquid in only one direction is provided (Japanese Utility Model Publication No. 4-39349). Further, in Japanese Unexamined Patent Publication No. 62-274143 and Japanese Utility Model Laid-Open No. 60-52458, the swing member and the damper device are separately provided, and each of them is separately mounted on the front surface of the cylinder block of the engine or the like. The structure for auto-tensioner is described.

Among the conventional techniques configured as described above, in the automatic tensioner disclosed in Japanese Patent Laid-Open Nos. 58-65357 and 63-180759, the pulley can be displaced only slowly in any direction. If the belt is slack, the pulley may not be able to follow it and the belt tension may temporarily drop. Further, the above-mentioned JP-A-63-167163, JP-A-2-72252, JP-A-2-80839, JP-A-3-24346, JP-A-2-16846 and JP-A-2-98243, In the case of the auto tensioner described in Japanese Patent Laid-Open No. 4-39349, the one-way clutch has fretting wear, resulting in insufficient durability (Japanese Patent Application Laid-Open No. 63-167163), and a complicated internal structure. It is difficult to manufacture at high cost, and the manufacturing cost is high (Tokukaihei 2-72252, 280839, 3-24346, Actual Kai 2-16846, 2-98243). The characteristics tend to change over time due to wear of the parts, and the resistance of the viscous liquid is large even when the belt is loosened, so that the followability of the pulley is not always sufficient (Japanese Patent Laid-Open No. 225 2 JP, same 3-24346, JP-real-Open 2-98243, JP same 4-39 349 JP) to. Further, in the case of the auto tensioner described in JP-A-62-274143 and JP-A-60-52458, the followability when the installation space is large or the belt tension is drastically reduced. Is bad.

[0008]

[Previous invention that is the prior art of the present invention]

 In consideration of the above-mentioned circumstances, the present inventor has previously devised an auto tensioner as shown in FIGS. 4 to 5 (Practical application Nos. 4-67543 (FIG. 4) and 5-29569 (FIG. 5). )).

Among them, the auto tensioner shown in FIG. 4 rotatably supports the base end portion of the swing member 12 around the fixed shaft 11 provided in the fixed member 10, and the tip end of the swing member 12 is rotatably supported. The part is provided with a pivot 13 parallel to the fixed shaft 11. A pulley 5 is rotatably supported around the pivot 13 and a belt 1 to which tension is applied is stretched around 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 to the swing member 12 in a direction of pressing the pulley 5 toward the belt 1, is arranged. . In addition, a pair of locking portions 16a and 16b provided at both ends of the torsion coil spring 14 are locked to the fixed member 10 and the rocking member 12, respectively, so that the rocking member 12 has the above-mentioned structure. Elasticity is applied in the direction of pressing the pulley 5 toward the belt 1.

Further, a damper device 19 is bridged between the fixed side arm piece 17 provided on the fixed member 10 and the swing side arm piece 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 piece 17, and the plunger 22 is attached to the lower surface of the receiving block 21 fixed to the tip of the swing arm piece 18. Is hitting the tip of.

On the other hand, in the auto tensioner shown in FIG. 5, the fixing member 10 is omitted from the structure shown in FIG. Then, a damper device 19 is supported on the tip end of the rocking side arm piece 18, and a portion of the lower end portion of the damper device 19 protruding from the lower surface of the rocking side arm piece 18 is fixed to the front surface of a cylinder block of the engine or the like. It can be abutted against a protrusion (not shown) formed on the part. The locking portion 16a of the torsion coil spring 14 is locked to the fixed portion.

In the case of the auto tensioner having any structure, the damper device 19 is configured as shown in FIG. 6 or 7. A cylinder cylinder 24, in which a viscous liquid 23 such as silicone oil is enclosed, has a bottomed cylindrical shape with an open upper end and a closed lower end. A piston 25 is fitted in the lower half of the inside of the cylinder cylinder 24 so as to be able to move up and down. There is a minute gap between the inner peripheral surface of the cylinder cylinder 24 and the outer peripheral surface of the piston 25. The viscous liquid 23 existing on the upper side and the lower side of the piston 25 slowly flows through the minute gap. An urging spring 26, which is a compression coil spring, is provided between the lower surface of the piston 25 and the upper surface of the bottom of the cylinder cylinder 24 to urge the piston upward. Further, the base portion 28 of the plunger 22 is fitted in the upper inner half portion of the cylinder cylinder 24 so as to be able to move up and down. A seal ring 29 is provided between the inner peripheral surface of the cylinder cylinder 24 and the outer peripheral surface of the base portion 28 to maintain liquid tightness between the peripheral surfaces. A plurality of notches 30, 30 are formed on the upper end surface of the piston 25, and the minute gaps are formed between the inner space 31 existing inside the abutting portion of the base 28 and the piston 25 through the notches 30, 30. And communicate with.

On the other hand, a through hole 33 is formed in the central portion of the partition wall 32 that constitutes the piston 25, and a passage that connects the upper and lower sides of the piston 25 is constituted. A check valve 34 that opens and closes the through hole 33 is provided in the lower portion of the partition wall 32. 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 biasing spring 26. It has the function of opening only when.

Further, in the case of the damper device 19 of the first example shown in FIG. 6, the outer diameter of the front half portion 27 of the plunger 22 is made sufficiently smaller than the inner diameter of the cylinder tube 24, and The viscous liquid 23 is also injected into the lower half of the upper space 35 between the outer peripheral surface of the first half 27 and the upper inner peripheral surface of the cylinder 24. The viscous liquid 23 is allowed to flow freely between the upper space 35 and the inner space 31 through the communication holes 36, 36 provided in the continuous portion of the base portion 28 and the first half portion 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 front half portion 27 to close the upper end opening portion of the upper space 35.

On the other hand, in the case of the damper device 19 of the second example shown in FIG. 7, the diameter of the first half portion 27a is made relatively large and the internal volume of the first half portion 27a is increased, but instead of the plunger 22. Communication holes 36, 36 (FIG. 6) through which the inside and outside are passed are omitted. When the damper device 19 shown in FIG. 7 is incorporated in the auto tensioner shown in FIG. 5, in the example shown in the drawing, the cylinder cylinder 24 is projected from the lower surface of the swing-side arm piece 18, and the cylinder cylinder 24 is The lower end surface of 24 can freely abut against the upper surface of a protrusion formed on a fixed portion such as the front surface of the cylinder block of the engine. 7 (A) shows the damper device in the contracted state, and FIG. 7 (B) shows the expanded state.

The autotensioner of the above-mentioned idea, which is configured by incorporating the damper device 19 configured as described above, is incorporated in an engine as shown in FIG. 8, for example, to drive a camshaft. Appropriate tension is applied to the belt 1. In the use state of the auto tensioner as shown in FIG. 8, the rocking member 12 rocks based on the elastic force of the torsion coil spring 14, and the rocking member 12 is rotatable about the pivot shaft 13 at the tip end thereof. The pulley 5 supported by is elastically pressed toward the belt 1. By pressing the pulley 5 against the belt 1, the rocking of the rocking member 12 is restricted. In this state, it is provided between the fixed side arm piece 17 (in the case of the structure of FIG. 4) or the protrusion (in the case of the structure of FIG. 5) formed on the fixed portion such as the cylinder block and the swing side arm piece 18. The damper device 19 is stretched between the fixed-side arm piece 17 or the protrusion and the swing-side arm piece 18 based on the elastic force of the biasing spring 26.

When the belt 1 is slackened from this state, the oscillating member 12 oscillates based on the elastic force of the torsion coil spring 14, causing the pulley 5 to follow the movement of the belt 1. At this time, the displacement of the plunger 22 constituting the damper device 19 is slightly delayed, so that the tip of the plunger 22 and the lower surface of the receiving block 21 (in the case of the structure shown in FIG. 4) or the cylinder tube 24. The lower surface and the upper surface of the protrusion (in the case of the structure shown in FIG. 5) are separated from each other. Therefore, when the belt 1 is loosened, the damper device 19 does not resist the rotation of the swinging member 12 so that the pulley 5 follows the movement of the belt 1. As a result, it is possible to cause the pulley 5 to quickly follow the movement of the belt 1 and prevent the tension of the belt 1 from decreasing. Due to the elasticity of the biasing spring 26, the entire length of the damper device 19 extends slightly later than the movement of the swing member 12.

As described above, when the damper device 19 extends due to the elasticity of the biasing spring 26, the check valve 34 opens. 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 23 is smoothly moved from the upper side to the lower side of the partition wall 32, and the piston 25 and the plunger 22 are moved up relatively quickly. 19 stretches between the fixed side arm piece 17 or the protrusion and the swing side arm piece 18.

On the contrary, when the tension of the belt 1 increases, the swing member 12 tends to rotate against the elastic force of the torsion coil spring 14. In this state, the rocking side arm piece 18 presses the damper device 19 in the compression direction. Therefore, in this case, in order to rotate the swinging member 12, the plunger 22 and the piston 25 must be pushed into the cylinder cylinder 24 against the elastic force of the biasing spring 26. At this time, since the check valve 34 remains closed, it is necessary to move the viscous liquid 23 present on the lower side of the piston 25 to the upper side of the piston 25 in order to lower the piston 25. It must be done through a minute gap existing between the inner peripheral surface of the cylinder cylinder 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 can be performed only slowly. As a result, the displacement of the pulley 5 supported by the swinging member 12 is only slowly performed 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. There is nothing to do.

[0020]

[Problems to be solved by the device]

 However, in the case of the damper device for an autotensioner according to the prior invention, which is constructed as described above and operates as described above in the state of being incorporated in the autotensioner, there are still the following points to be improved.

That is, when the total length of the damper device 19 is shortened as the tension of the belt 1 is increased, the lower surface of the receiving block 21 is located at the tip of the plunger 22 (in the case of the structure shown in FIG. 4) or the cylinder. The lower surface of the cylinder 24 is abutted against the upper surface of the projection (in the case of the structure shown in FIG. 5), respectively. The force applied from the receiving block 21 or the projection to the plunger 22 or the cylinder cylinder 24, respectively. Is not necessarily parallel to the axes of these members 22, 24.

For example, when shortening the entire length of the damper device 19 having the structure shown in FIG. 7, as shown in FIG. 9, from the receiving block 21 to the top of the plunger 22, with respect to the central axis a of the plunger 22. A non-parallel force F may be applied. In such a case, a rotational moment about an axis orthogonal to the central axis a is generated in the plunger 22 and the piston 25 pressed by the plunger 22. Based on this rotation moment, as shown in FIG. 9, edge load α is generated at the upper and lower end edges of the plunger 22 and the piston 25, and the contact surface pressure of that portion is significantly increased. Wear is significantly accelerated.

The damper device for an automatic tensioner of the present invention is designed to eliminate such inconvenience.

[0024]

[Means for solving the problem]

 The damper device for an autotensioner according to the present invention includes a fixing member, a fixing shaft provided on the fixing member, a swinging member whose base end is rotatably supported around the fixing shaft, and a swinging member. A pivot that is provided at the tip of the moving member and that is parallel to the fixed shaft, a pulley that is rotatably supported around the pivot, and an elastic force in a direction that presses the pulley toward the belt are the swinging member. It is assembled in an autotensioner equipped with a tension-applying spring that is applied to the swing member between the swing-side arm piece provided on the swing member and a fixed portion.

Such a damper device for an autotensioner of the present invention, like the damper device incorporated in the autotensioner of the previous invention described above, has a cylinder cylinder in which a viscous liquid is sealed and an inside of the cylinder cylinder. A piston fitted axially in a freely displaceable manner, an urging spring provided between the piston and the cylinder cylinder for urging the piston in one direction, and one half of the inside of the cylinder cylinder. A plunger that has a cylindrical portion that is in sliding contact with the peripheral surface and that increases the amount of protrusion from the cylinder tube in accordance with the displacement of the piston due to the elastic force of the biasing spring and the axial end surfaces of the piston communicate with each other. And a check valve for opening and closing the passage. The check valve has a function of opening only when the piston is displaced based on the elastic force of the biasing spring.

In particular, in the damper device for an autotensioner of the present invention, the outer diameter of the outer peripheral surface of at least one of the piston and the cylindrical portion becomes smaller toward the edge. It features a crowning shape.

[0027]

[Action]

 In the damper device for an autotensioner of the present invention configured as described above, the action itself at the time of limiting the displacement of the swing member supporting the pulley in order to suppress the vibration of the belt in the state of being incorporated in the autotensioner is as follows. This is the same as in the case of the damper device incorporated in the auto tensioner of the previous invention described above.

Particularly, in the damper device for an autotensioner of the present invention, since the axial end portions of at least one outer peripheral surface of the piston and the cylindrical portion of the plunger are crowned, Even when a force non-parallel to the central axis is applied, the edge load does not occur on the outer peripheral surface.

[0029]

【Example】

 1 and 2 show an embodiment of the present invention. A viscous liquid 23 is enclosed in a cylindrical cylinder cylinder 24 having a bottom and an upper end opened, and a piston 25 is vertically movable. An urging spring 26 is provided between the lower surface of the piston 25 and the upper surface of the bottom of the cylinder tube 24 to give the piston 25 upward elasticity. A plunger 22a is provided above the piston 25. The amount of protrusion of the plunger 22a from the cylinder cylinder 24 increases as the piston 25 rises due to the elastic force of the biasing spring 26. Further, a through hole 33 is formed in the central portion of the partition wall 32 of the piston 25 to form a passage that connects the upper side and the lower side of the piston 25. Further, a check valve 34 including a spring 38 and a ball 39 is provided on the lower side of the partition wall 32. The check valve 34 opens only when the piston 25 rises due to the elastic force of the biasing spring 26.

In the lower half of the plunger 22a, a cylindrical portion 41 that is in sliding contact with the inner peripheral surface of the cylinder tube 24 is provided, and in the upper half, an outer diameter that is slightly smaller than the inner diameter of the cylinder tube 24. The small diameter portions 42 having the above are respectively formed. The lower end of the cylindrical portion 41 is open and the upper end of the small diameter portion 42 is closed, so that the plunger 22a is formed in a bottomed cylindrical shape. A through hole 43 is formed at the upper end of the plunger 22a to communicate the inside and outside of the plunger 22a to prevent the pressure in the inner space 31 from rising excessively. A dust-removing filter (not shown) having appropriate air permeability is fitted and fixed inside the upper portion of the small diameter portion 42 to cover the inner cross section of the small diameter portion 42.

Further, in the damper device for an autotensioner of the present invention, as shown in an exaggerated manner in FIG. 2, it is formed on the upper and lower end portions of the outer peripheral surface of the piston 25 and the lower half portion of the plunger 22a. The upper and lower ends of the outer peripheral surface of the cylindrical portion 41 are formed into a crowning shape whose outer diameter becomes smaller toward the edge.

With the damper device for an autotensioner of the present invention having the above-described structure installed in the autotensioner as shown in FIG. 4 or 5, the pulley for suppressing the vibration of the belt 1 The action itself when limiting the displacement of the rocking member 12 supporting 5 is the same as that of the damper device incorporated in the above-mentioned autotensioner of the prior invention.

Particularly, in the damper device for an autotensioner of the present invention, since the upper and lower end crowning shapes of the outer peripheral surface of the piston 25 and the cylindrical portion 41 are formed, as shown in FIG. Even when a force non-parallel to the central axis is applied, the load β generated on each outer peripheral surface is smaller than that of the conventional structure shown in FIG. 9 as shown in FIG. Therefore, a large edge load does not occur at the edge of each outer peripheral surface.

In the illustrated embodiment, the present invention is applied to the structure shown in FIG. 7, but it is obvious that the same can be applied to the structure shown in FIG.

[0035]

[Effect of device]

 The damper device for an autotensioner of the present invention is constructed and operated as described above, and in order to prevent a large edge load from being generated in a portion slidingly contacting the inner peripheral surface of the cylinder cylinder, the surface pressure of the sliding contact portion is prevented. The rise can be prevented, the wear of the sliding contact portion can be prevented, and the durability of the damper device can be improved.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a portion A of FIG. 1 in a state in which a bending amount in a thickness direction is exaggerated with respect to a dimension in an axial direction.

FIG. 3 is a front view showing an example of a conventional usage state of an automatic tensioner.

FIG. 4 is a front view showing a first example of an automatic tensioner according to the prior invention.

FIG. 5 is a front view showing the second example.

FIG. 6 is a vertical cross-sectional view showing a first example of a damper device incorporated in the auto tensioner according to the previous invention.

FIG. 7 is a longitudinal sectional view showing the second example in a contracted state and an expanded state.

FIG. 8 is a state 1 of use of the auto tensioner according to the previous invention.
The front view which shows an example.

FIG. 9 is a vertical cross-sectional view showing a state in which a non-parallel force is applied to the plunger of the damper device.

[Explanation of symbols]

 1 belt 2 drive pulley 3 driven pulley 4 guide 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 part 16a, 16b locking part 17 fixed Side arm piece 18 Swing side arm piece 19 Damper device 20 Cylinder tube 21 Receiving block 22, 22a Plunger 23 Viscous liquid 24 Cylinder tube 25 Piston 26 Energizing spring 27, 27a Tip half 28 Base 29 Seal ring 30 Notch 31 Inside 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 Cylindrical part 42 Small diameter part 43 Through hole

Claims (1)

[Scope of utility model registration request] 1. A fixed member, a fixed shaft provided on the fixed member, a swinging member whose base end is rotatably supported around the fixed shaft, and a tip end of the swingable member. A pivot provided parallel to the fixed shaft, a pulley rotatably supported around the pivot, and a tensioning spring for imparting elastic force to the swing member in a direction of pressing the pulley toward the belt. A cylinder cylinder that is incorporated in an autotensioner equipped with the above-mentioned structure in a state of being bridged between the rocking side arm piece provided on the rocking member and a fixed portion, and a viscous liquid is sealed inside, and a cylinder cylinder of this cylinder cylinder. A piston that is fitted inside so as to be displaceable in the axial direction, an urging spring that is provided between the piston and the cylinder cylinder, and urges the piston in one direction, and one half of the cylinder cylinder. It has a cylindrical part that is in sliding contact with the inner peripheral surface, and A plunger that increases the amount of protrusion from the cylinder cylinder in accordance with the displacement of the piston based on the resilience of the knee, a passage that connects both axial end faces of the piston, and a check valve that opens and closes the passage are provided. In the damper device for an automatic tensioner having a function of opening only when the piston is displaced based on the elastic force of the biasing spring, the check valve has an outer periphery of at least one of the piston and the cylindrical portion. A damper device for an automatic tensioner, characterized in that both axial ends of the surface are crowned so that the outer diameter becomes smaller toward the edge.