JPH08210447A - Autotensioner - Google Patents

Abstract

PURPOSE: To easily surely adjust preset tension of an autotensioner. CONSTITUTION: Here are respectively provided a through hole 25 in a rocking arm 13 and a slot 24 in a center part of an inner ring member 16 of supporting a pulley 5. This slot 24 is formed in a circular arc shape with a pivotal shaft, which is the rocking center of the rocking arm 13, rocking as the center. In the case of supporting the inner ring member 16 to the rocking arm 13, a nut 22 is screwed to be tightened to a bolt 21 inserted to each of these holes 24, 25. In the case of adjusting preset tension, in a condition that this bolt 21 is loosened, the pulley 5 is displaced in a range of the slot 24. When the pulley 5 leads to a desired position, the bolt 21 and the nut 22 are tightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The automatic tensioner according to the present invention is a timing belt for an automobile engine, or a belt for driving an auxiliary machine such as an alternator or a compressor (hereinafter, these are collectively referred to as "belt"). ) To give the proper tension.

[0002]

2. Description of the Related Art Since a camshaft of an OHC type engine or a DOHC type engine is rotationally driven in synchronization with a crankshaft, a drive device using a belt 1 as shown in FIG. 6 is widely used. In FIG. 6, 2 is a drive pulley that is driven to rotate by the crankshaft of the engine, 3 is a driven pulley fixed to the end of the camshaft, 4 and 4 are for guiding the belt 1, or are water pumps. Guide pulleys or driven pulleys for driving auxiliary machines such as 5 are belts 1
This is a pulley for applying proper tension to the.

The pulley 5 is pivotally supported by a rocking member 7 which rocks around a pivot 6. A spring 8 is provided at the end of the bracket 7a fixed to the swing member 7.
By elastically pressing the pulley 5 toward the belt 1, the tension of the belt 1 is always maintained irrespective of the dimensional change of the belt 1 or the like due to temperature change or the like or the vibration accompanying the operation of the engine. I try to keep it constant.

By the way, the belt 1 is included in the auto tensioner.
In addition to the function of applying tension to the belt, a function of holding down the belt 1 is required. That is, in the camshaft drive device shown in FIG. 6, when the drive pulley 2 is rotated, a part of the belt 1 located between the pulleys 2 to 5 is
It tends to vibrate in a direction perpendicular to the traveling direction. If this shake is allowed as it is, the amplitude of the shake becomes large (vibration grows), abnormal vibration occurs in the driving portion by the belt 1, or in the case of a toothed belt, so-called tooth skipping occurs. Cause problems.

As an auto tensioner for preventing such a problem, Japanese Laid-Open Patent Publication No. 62-274143 and Shokai Sho 60 are known.
No. 52458 discloses an auto tensioner equipped with a damper device. FIG. 7 shows a conventional auto tensioner equipped with such a damper device.

A swing member 7 supporting the pulley 5 is pivotally supported by a pivot shaft 6 on a base body such as the front surface of a cylinder block of an engine. The pulley 5 has a pivot 6 attached to the swing member 7.
It is rotatably supported about an axis parallel to.
That is, the inner ring member 16 having the shape of a short cylinder with a bottom, which is the support member described in the claims, is fixed to the tip end portion of the swing member 7 with the bolt 21 and the nut. The pulley 5 is rotatably supported around the inner ring member 16 via a plurality of balls.

Cylinder cylinder 9 constituting the damper device 12
Is fixed to the base body separately from the swing member 7, and the hollow piston 15 can be displaced in the viscous fluid enclosed in the cylinder cylinder 9. This piston 15
A compression spring 11 is provided between one end surface (lower end surface in FIG. 7) of the cylinder and the rear end surface (lower end surface in FIG. 7) of the cylinder cylinder 9, and the other end surface (upper end surface in FIG. 7) of the piston 15 is provided. The base end portion (lower end portion in FIG. 7) of the push rod 10 is connected. The tip end portion (upper end portion in FIG. 7) of the push rod 10 abuts against a part of the rocking member 7 so that the elastic force of the compression spring 11 can be transmitted to the rocking member 7. Therefore, the pulley 5 is pressed against the belt 1 based on the elasticity of the compression spring 11. In addition, as described in Japanese Utility Model Laid-Open No. 60-52458, the compression spring 11 in the damper device 12 is
In addition to the above, the swing member 7 may be provided with a spring.

On the other hand, the pair of chambers 17 and 18 existing on both sides of the piston 15 are communicated with each other through an oil passage 19 provided at the center of the piston 15 and the push rod 10. A check valve 20 is provided at the open end of the oil passage 19 so that the check valve 20 opens only when a viscous fluid flows toward the chamber 17 provided with the compression spring 11.

In the case of the conventional automatic tensioner having such a structure, the push rod 10 is rapidly displaced in the projecting direction (upward direction in FIG. 7) and only slowly in the retracting direction (downward direction). . Therefore, when the belt 1 is slackened, the pulley 5 is swiftly followed, and when the belt 1 is tensioned, the belt 1 is held down without retracting the pulley 5. Therefore, the above auto tensioner
The tension of the belt 1 can always be kept constant irrespective of the dimensional change of the belt 1 and the like due to temperature change and deterioration of the belt 1, or the vibration and the like accompanying the operation of the engine. In the case of the above auto tensioner, the compression spring 11 constitutes the damper device 12 and also has the function of imparting the elastic force in the direction toward the belt 1 to the swing member 7 as described above.

By the way, in order to make the tension of the belt 1 proper, it is necessary to make the tension (set tension) proper when the auto tensioner is assembled to the base body. That is, when the autotensioner is assembled to the base body, the assembly position of the pulley 5 may be different from that at the design stage due to an error in the mounting dimension of the engine, the cylinder block, etc., the processing dimension and the like. Since the spring constant of the compression spring 11 is determined according to the mounting position at the designing stage, if the mounting position of the pulley 5 is different from that at the designing stage as described above, it is determined that the spring constant is appropriate. However, the tension of the belt 1 varies. Further, when there is a large error in the above-mentioned mounting dimensions, processing dimensions, etc., it is necessary to adjust each part at the time of assembly. If this adjustment work is not performed, the stroke amount of the damper device 12 may be insufficient during engine operation, and the pulley 5 may not be able to follow changes in the tension of the belt 1.

However, in the case of the auto tensioner shown in FIG. 7, the work of adjusting the set tension as described above is not considered. That is, the mounting positions of the swing member 7 and the damper device 8 are unitarily determined. Therefore, if there is an error as described above, is it possible to perform the adjustment work?
Even if you could do it, it would be extremely troublesome.

There has been known an automatic tensioner which eliminates such inconvenience and can easily perform the work of adjusting the set tension. For example, Japanese Utility Model Publication No. 4-30450 describes a structure in which a swing member having a pulley attached thereto and a damper device are provided on a single base plate. When assembling such an automatic tensioner to the base body, the set tension is adjusted by fixing the base plate to the base body while rotating the base plate by a desired amount around the fulcrum. In addition, Japanese Patent Fair 5-2
Japanese Patent No. 852 describes a technique in which a pulley and a damper device (direct acting actuator) are integrally rotatable. Also in the case of this structure, when the auto tensioner is mounted on the base body of the engine or the like, the set tension is adjusted by fixing the pulley and the damper device to the base body in a rotated state.

Further, Japanese Utility Model Publication No. 4-30450,
In addition, Japanese Utility Model Publication No. 4-25555 discloses a structure in which only the swing arm 13 is rotatable as shown in FIG. 8 and the pulley 5 is eccentrically provided on the swing arm 13. There is. When adjusting the set tension of the automatic tensioner having such a structure, the pulley 5 is rotated by a desired amount about the eccentric shaft 14 provided in parallel with the pivot shaft 6. This changes the amount of protrusion of the pulley 5 toward the belt 1,
The tension of the belt 1 is fixed to a desired value.

[0014]

In each of the above-described conventional autotensioners, the set tension of the belt 1 can be set to a desired value. However, each of the above-mentioned auto tensioners has the following disadvantages. That is, in the automatic tensioner described in the above Japanese Utility Model Publication No. 4-30450, which has a structure in which a swing member having a pulley and a damper device are provided on one base plate, these swing members and Damper device should be installed,
A relatively large base plate is required. Since such a base plate is provided, the manufacturing cost increases. Moreover, since the base plate having such a large area can be freely rotated, a large space must be secured in the assembly portion. Therefore, the space around the entire auto tensioner and the portion where the auto tensioner is assembled increases. In addition, the Japanese Patent Publication 5-2
In the auto tensioner described in Japanese Patent Publication No. 852, in which the pulley and the damper device are integrally rotatable, the portion to which the auto tensioner is also assembled in order to integrally rotate the pulley and the damper device. The space around it becomes bulky.

Further, Japanese Utility Model Publication No. 4-30450,
Also, in the auto tensioner having the structure in which the pulley is eccentrically provided on the swing arm described in Japanese Utility Model Publication No. 4-25555, there is no such inconvenience as described above, but instead the following inconvenience is present. Exists. That is, in this auto tensioner, the pulley 5 is used to adjust the set tension.
Is rotated about the eccentric shaft 14 by a desired amount. When the pulley 5 is rotated about the eccentric shaft 14 in this way, the distance between the center of swinging of the swinging arm 13 (the pivot shaft 6) and the center of the pulley 5 becomes as shown in FIG. What was L in
After the rotation, it becomes L '(L ≠ L'). Swing arm 1
If the distance between the swing center of 3 and the center of the pulley 5 changes, the mechanical balance of the auto tensioner changes.
That is, a change in the distance between the swing center of the swing arm 13 and the rotation center of the pulley 5 changes the lever ratio of the force transmitted from the auto tensioner to the pulley 5. As a result, the tension of the belt 1 changes. In addition, this FIG.
In the drawing, the state after the pulley 5 is rotated around the eccentric shaft 14 is shown with the swing arm 13 swinging. This is because it is easy to see the distances L and L '. This is because the swing arm 13 does not swing with the rotation of the pulley 5 about the eccentric shaft 14.

As described above, in the case of the autotensioner having the structure in which the pulley 5 is eccentrically provided on the rotatable swing arm 13, the dimensional error of each constituent member that causes the tension change of the belt 1 can be eliminated, Center of swing of swing arm 13 and pulley 5
The distance from the center of rotation of the belt changes, and as a result, the tension of the belt 1 changes. That is, while trying to make the set tension proper when the auto tensioner is assembled, the set tension becomes improper in the end. The autotensioner of the present invention is designed to eliminate any of the above-mentioned inconveniences.

[0017]

The autotensioner of the present invention, like the conventional autotensioner described above, has a first shaft supported by a base body and a base end portion pivotally supported by the first shaft. A swinging member, a support member provided at the tip of the swinging member, the support member having an axis parallel to the first axis, and rotatable around the support member around the axis of the support member. A supported pulley, a spring that applies an elastic force to the swing member in a direction of pressing the pulley toward the belt, and a damper device that serves as a resistance against displacement of the pulley against the elastic force of the spring. Prepare Particularly, in the autotensioner of the present invention, an arc-shaped elongated hole centered on the first shaft, which is formed in at least one of the central portion of the support member and the tip portion of the swing member, A connecting and fixing member that is inserted into the elongated hole and is parallel to the first axis is provided.

[0018]

The action of the autotensioner of the present invention constructed as described above to press the belt by the pulley, the action of causing the pulley to follow the movement of the belt, and the action of suppressing the vibration of the belt by the pulley are as described above. It is similar to the auto tensioner. In particular, in the auto tensioner of the present invention, the work of adjusting the set tension of the belt can be easily and surely performed by appropriately changing the mounting position of the supporting member with respect to the swinging member within the range of the length of the long hole. It Moreover, since this adjustment work can be performed by relatively displacing the supporting member and the swinging member, the space around the installation portion does not become large. Further, since the elongated hole is formed in an arc shape centered on the first axis which is the swing center of the swing member, even when the assembly position of the pulley with respect to the swing member is changed,
The distance between the first shaft and the shaft of the support member, which is the center of rotation of the pulley, does not change. Therefore, the mechanical balance of the auto tensioner does not change, and a desired set tension can be easily and reliably obtained.

[0019]

Embodiments Next, the illustrated embodiments will be described. Figure 1
2 shows a first embodiment of the present invention in which the present invention is applied to the auto tensioner shown in FIG. The same parts as those of the conventional device described above will be designated by the same reference numerals to omit or simplify the description, and the characteristic part of the present invention will be mainly described below. As shown in FIG. 1, the pulley 5 is supported by a swing member 7 which swings around a pivot shaft 6 which is a first shaft provided on a base body such as the front surface of a cylinder block of an engine. The pivot 6 is composed of, for example, a bolt and a plain bearing. From the base end portion (lower end portion in FIG. 1) of the swinging member 7 to the tip end portion (upper end portion in FIGS. 1 and 2) of the swinging arm 13 that continues upward in FIG. The cylindrical inner ring member 16 is fixed by a bolt 21 and a nut 22. The bolt 21 forms a connecting and fixing member, and is an axis parallel to the pivot 6. The pulley 5 is rotatably supported around the inner ring member 16 via a plurality of balls 23.

The above-mentioned structure is the same as that of the conventional example shown in FIG. 7, but in the present invention, the inner ring member 16 has a circular arc shape centered on the pivot 6 at the central portion thereof. The long holes 24 are formed. Then, the bolt 21 is inserted into the long hole 24, and further, the bolt 21 is inserted into the through hole 25 provided in the swing member 7, and the nut 22 is screwed into the distal end portion thereof to tighten them. Thereby, the pulley 5 is rotatably centered on the shaft of the inner ring member 16 so that the swing arm 13 can rotate.
I support it.

The autotensioner of the present invention having the above-mentioned structure presses the belt 1 with the pulley 5, causes the pulley 5 to follow the movement of the belt 1, and suppresses the vibration of the belt 1 with the pulley 5. The operation is similar to that of the conventional auto tensioner described above. Particularly, in the auto tensioner of the present invention, the inner ring member 16 for pivotally supporting the pulley 5 is supported on the swing member 7 by the bolt 21 inserted into the elongated hole 24. Therefore, when the auto tensioner is assembled to the base body of the engine or the like, the work of adjusting the tension applied to the belt can be easily and reliably performed.

That is, the inner ring member 16 which supports the pulley 5 in a state where the bolt 21 is inserted into the long hole 24 and the through hole 25 and loosely screwed into the nut 22 has the length of the long hole 24. Can be freely displaced within the range of (strictly, "length-outer diameter of bolt 21"). Therefore, when adjusting the set tension of the belt 1, the pulley 5 is appropriately displaced along the elongated hole 24. Then, when the pulley 5 reaches a desired position (the tension of the belt 1 pushed by the pulley 5 reaches a desired value), the nut 22 is tightened, and the inner ring member 16 is supported and fixed to the swing arm 13. To do. In this case, the distance between the pivot shaft 6 which is the swing center of the swing member 7 and the center shaft of the inner ring member 16 which is the rotation center of the pulley 5 does not change before and after the adjustment work. Therefore, the mechanical balance of the auto tensioner does not change, and a desired set tension can be easily and reliably obtained. Further, in the case of the present embodiment, since only the swinging member 7 provided with the pulley 5 rotates, the space around the installation portion does not become large.

In the above embodiment, the rocking member 7 is used.
A through hole 25 is formed in the bolt 2 and the bolt 2 is inserted through the through hole 25.
1 is screwed into the nut 22 and tightened, but as shown in FIG. 3, a screw hole 26 is provided in place of the through hole 25, and the long hole 24
Alternatively, the bolt 21 inserted through may be screwed into the screw hole 26. Further, the long hole 24 is formed in the swing arm 13, the through hole is formed in the inner ring member 16, and the nut 22 is screwed into the through hole and the bolt 21 inserted into the long hole 24 so as to be tightened. You can Further, the elongated hole 24 can be formed in both the inner ring member 16 and the swing arm 13.
However, in this case, the bolt 21 is screwed into the nut 22 and tightened. Further, when the set tension is adjusted, the inner ring member 16 and the swing arm 13 are arranged so that they can be displaced along the elongated hole 24 without rotating around the bolt 21. The members 16 and 13 may be engaged and recessed so that only the relative displacement along the elongated hole 24 can be freely performed. For example, as shown in FIG. 3, the elongated hole 24 is formed in the inner ring member 16.
The arcuate convex portion 27 having the same center as that of the swing arm 1
3, arc-shaped recesses 28 which also have the same center as that of the elongated hole 24 are formed respectively.
And 7 are engaged.

Next, referring to FIG. 4, the present invention will be described with reference to FIG.
Applied to the auto tensioner described in Japanese Patent No. 57,
2 shows a second embodiment of the present invention. This autotensioner rotatably supports a base end portion (lower end portion in FIG. 4) of a swinging member 31 around a fixed shaft 30 which is a first shaft provided on a fixing member 29, and swings the swinging member 31. An inner ring member 16 having an axis parallel to the fixed shaft 30 is fixed to a tip end portion (upper end portion in FIG. 4) of the member 31 with a bolt 21. Then, the pulley 5 is rotatably supported around the inner ring member 16,
A belt 1 to which a tension is applied is stretched around the pulley 5. The torsion coil spring 3 is provided around the fixed shaft 30.
Two coil portions 33 are arranged. Also, a pair of locking portions 34a, 34b provided at both ends of the torsion coil spring 32.
Is locked to the fixing member 29 and the swinging member 31, respectively, so that the swinging member 31 is given an elastic force in a direction of pressing the pulley 5 toward the belt 1. still,
The stopper pin 41 provided between the fixed member 29 and the swinging member 31 is pulled out after the belt 1 is stretched over the pulley 5, and these two members 29, 3 centered on the fixed shaft 30 are provided.
Allows relative displacement of one to the other.

Further, the fixed arm 35 provided on the fixing member 29.
A damper device 37 is provided between the swing arm 36 and the swing arm 36 provided on the swing member 31. That is, in the case of the present embodiment, the base end portion of the cylinder tube 38 constituting the damper device 37 is fixed to the tip end portion of the fixed arm 35, and the bottom surface of the receiving block 39 fixed to the tip end portion of the swing arm 36 is fixed. The tip end of the plunger 40 that constitutes the damper device 37 is abutted. The damper device 37 has substantially the same configuration and operation as the damper device 12 described above, and is quickly displaced in the extension direction, but is only slowly displaced in the compression direction. However, since the damper device 37 does not have the action of pressing the pulley 5 against the belt 1, the spring built in the damper device 37 is small. Since such a damper device 37 is not the gist of the present invention, detailed description thereof will be omitted.

In particular, in the present invention, an arc-shaped elongated hole 24a centering on the fixed shaft 30 is formed at the center of the inner ring member 16 supporting the pulley 5. Then, the inner ring member 16 is supported and fixed to the swinging member 31 in a state where the bolt 21 which is the coupling fixing member is inserted into the elongated hole 24a. Therefore, when adjusting the set tension of the auto tensioner, even if the inner ring member 16 supporting the pulley 5 is rotated, the distance between the center of the pulley 5 and the fixed shaft 30 does not change, and the set tension is adjusted. Can be performed easily and surely. The operation in this case is similar to that of the first embodiment.

Next, FIG. 5 shows the present invention in Japanese Patent Application No. 5-29.
The 3rd example of the present invention applied to the auto tensioner concerning the former invention described in No. 569 is shown. The auto tensioner of the present embodiment has the fixing member 29 omitted from the structure of the second embodiment. The damper device 37 is supported on the tip end of the swing arm 36, and the damper device 37
The lower end of the swing arm 36 protruding from the lower surface,
It can freely abut against a protrusion (not shown) formed on a fixed portion such as the front surface of the cylinder block of the engine. The locking portion 34a of the torsion coil spring 32 is locked to the base body. In other configurations, an arc-shaped elongated hole 24b centering on the fixed shaft 30 is provided in the center portion of the inner ring member 16 supporting the pulley 5 or the swing member 31, which is a characteristic part of the present invention. The configuration is similar to that of the second embodiment, including a configuration in which the inner ring member 16 that supports the pulley 5 is supported and fixed to the swinging member 31 via the bolt 21 that is a coupling and fixing member that is inserted through the long hole 24b. Also, the action as an auto tensioner,
Also, the action when adjusting the set tension is the same as in the second embodiment. However, in the present embodiment, the effect of the previous invention that the size and weight can be reduced as compared with the structure of the second embodiment is directly maintained by omitting the fixing member 29.

[0028]

Since the autotensioner of the present invention is constructed and operates as described above, the tension applied to the belt can be adjusted easily and reliably. Therefore, it is possible to eliminate the dimensional error of each component member that causes the change in the belt tension. Moreover, at this time, since the distance between the swing center of the swing arm and the center of the pulley does not change, the mechanical balance of the auto tensioner does not change, and the desired set tension can be easily adjusted.
And surely obtained. Further, since only the swing arm rotates during assembly, the space around the installation portion does not become large.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view similar to FIG. 2, showing another example of the support structure for the pulley and the swing arm.

FIG. 4 is a front view showing a second embodiment of the present invention.

FIG. 5 is a front view showing the third embodiment.

FIG. 6 is a front view showing a belt drive device of an engine provided with an auto tensioner.

FIG. 7 is a sectional view showing a first example of a conventional structure.

FIG. 8 is a sectional view showing the second example.

FIG. 9 is a diagram schematically showing an unfavorable state.

[Explanation of symbols]

 1 belt 2 drive pulley 3 driven pulley 4 guide pulley or driven pulley 5 pulley 6 pivot 7 swing member 7a bracket 8 spring 9 cylinder cylinder 10 push rod 11 compression spring 12 damper device 13 swing arm 14 eccentric shaft 15 piston 16 inner ring Members 17, 18 Chamber 19 Oil passage 20 Check valve 21 Bolt 22 Nut 23 Ball 24, 24a, 24b Long hole 25 Through hole 26 Screw hole 27 Convex portion 28 Recessed portion 29 Fixed member 30 Fixed shaft 31 Swing member 32 Torsional coil Spring 33 Coil part 34a, 34b Locking part 35 Fixed arm 36 Swing arm 37 Damper device 38 Cylinder tube 39 Receiving block 40 Plunger 41 Stopper pin

Claims (1)

[Claims] 1. A first shaft supported by a base body, a swing member having a base end portion pivotally supported by the first shaft, and the first shaft provided at a tip end portion of the swing member. A support member having an axis parallel to the support member, a pulley rotatably supported around the support member around the support member, and the elastic force in the direction of pressing the pulley toward the belt. In an autotensioner equipped with a spring applied to a member and a damper device serving as resistance against displacement of the pulley against the elastic force of the spring, a central portion of the supporting member and a tip of the swinging member. Formed on at least one of the parts,
An autotensioner comprising: an arc-shaped elongated hole having the first axis as a center; and a coupling fixing member that is inserted into the elongated hole and is parallel to the first axis.