JP2000170857A - Hydraulic auto-tensioner and belt tension adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic auto-tensioner capable of being easily assembled. SOLUTION: A snap ring 4 is engaged with an engage groove 3 formed on an inner peripheral of an opening part of a cylinder 1 to prevent slip off an oil seal 2 sealing the opening part. A hydraulic damper 10 is connected to a lower end of a rod 5 slidably passing through the oil seal 2. Pressure force of a tension adjusting spring 8 is add on a spring seat 6 fixed on an upper part of the rod 5. The snap ring 4 is allowed to be a rose snap 4 ring providing a plurality of engage pieces 4c on an outer periphery thereof, and the rose snap 4 and the oil seal 2 is exteriorly provided on the rod 5. The rod 5 is inserted in the cylinder 1, and by thrusting of a projecting part 6b provided on a bottom surface of the seat spring 6, the snap ring 4 is engaged with the engage groove 3 to facilitate assembling thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic auto-tensioner for maintaining a constant tension of a belt for driving an auxiliary machine such as an alternator.

[0002]

2. Description of the Related Art As this type of hydraulic auto-tensioner, those already proposed by the present applicant have been known (Japanese Utility Model Laid-Open No. 5-10849) and
-42393 publication).

In the above-mentioned hydraulic auto-tensioner, a rod is slidably penetrated through an oil seal for sealing an upper opening of a cylinder, and an elastic force of a tension adjusting spring is applied to the rod to provide an outward projecting property. ing.

Further, when the rod is pushed in due to an increase in the tension of the belt, the pushing force is buffered by a hydraulic damper provided inside the cylinder.

[0005] The hydraulic auto tensioner described in Japanese Utility Model Laid-Open No. 5-10849 has a structure in which a tension adjusting spring for providing a rod with an outward projecting property is provided outside the cylinder. As compared with a hydraulic auto tensioner in which a tension adjusting spring is incorporated in a cylinder like an auto tensioner described in Japanese Patent Application Laid-Open No. 9-42393, a tension adjustment with a small spring constant and a large spring load is performed. A feature is that a spring can be used, and the responsiveness of the hydraulic auto tensioner can be improved.

[0006]

By the way, in any of the above-mentioned hydraulic auto-tensioners, an engagement groove is formed on the inner periphery of the upper opening of the cylinder, and a C-shaped retaining ring is engaged with the engagement groove. In order to assemble the auto tensioner, it is necessary to insert the rod into the cylinder, insert the oil seal along the rod into the cylinder, and then install the retaining ring. It takes time to assemble. In particular, in an auto-tensioner of a spring exterior type in which a tension adjusting spring is provided outside the cylinder (automatic tensioner of Japanese Utility Model Laid-Open No. 5-10849), the tension adjusting spring is fitted to the outside of the cylinder after the retaining ring is attached, and the rod is adjusted. It becomes necessary to connect the spring seat and the spring seat.
There are still points to be improved.

An object of the present invention is to provide an automatic tensioner which is easy to assemble.

[0008]

According to the present invention, an engagement groove is formed in an inner periphery of an upper opening of a cylinder filled with hydraulic oil, and the engagement groove is formed in the engagement groove. The engaged seal ring prevents the oil seal that seals the opening from coming off, applies the elastic force of a tension adjusting spring to the rod that slidably penetrates the oil seal, and presses the rod and cylinder in opposite directions. A hydraulic auto-tensioner configured to buffer a pushing force when the rod and the cylinder are pressed in a direction in which the rod and the cylinder are relatively contracted by a hydraulic damper provided inside the cylinder.
As the retaining ring, a chrysanthemum-shaped retaining ring having a rod insertion hole at the center and having a plurality of engaging pieces capable of engaging with the engaging groove formed on an outer peripheral portion is used.

With the above construction, after the chrysanthemum-shaped retaining ring and the oil seal are fitted to the outside of the rod, the rod is inserted into the cylinder, and the chrysanthemum-shaped retaining ring is pushed in the axial direction. The engagement piece is engaged with the engagement groove, and the engagement can hold the oil seal in an assembled state, so that the auto tensioner can be easily assembled.

Here, if the engagement piece of the chrysanthemum-shaped retaining ring is bent to one side of the retaining ring, the retaining ring can be smoothly inserted into the cylinder, and the retaining ring can be mounted more easily. it can.

Further, the tension adjusting spring is provided outside the cylinder, and a spring seat for receiving the elastic force of the tension adjusting spring is mounted on an upper portion of the rod. If provided, the protrusion pushes the chrysanthemum retaining ring by pushing the rod, so that no tool is required for mounting the chrysanthemum retaining ring, and the hydraulic auto tensioner can be more easily assembled.

In the belt tension adjusting device in which the adjusting force of the various auto-tensioners described above is applied to a belt for driving an engine accessory such as an alternator so as to keep the belt tension constant, the belt tension adjusting device is used. The apparatus can be easily assembled.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the inside of a cylinder 1 is filled with hydraulic oil, and an oil seal 2 for preventing the hydraulic oil from leaking outside is inserted into an upper opening.
An engagement groove 3 is formed on the inner periphery of the opening of the cylinder 1, and a retaining ring 4 for preventing the oil seal 2 from coming off is attached to the engagement groove 3.

As shown in FIGS. 2 (I) and (II), the retaining ring 4 has a rod insertion hole 4b formed in the center of a disk portion 4a made of an elastic plate such as a stainless steel plate or a spring steel plate. A plurality of engagement pieces 4c are provided on the outer periphery of the portion 4a, and each engagement piece 4c is provided.
c is bent to the lower surface side of the disk portion 4a, and is formed of a chrysanthemum-shaped retaining ring.

A rod 5 is slidably inserted through the oil seal 2 and the retaining ring 4. A spring seat 6 is fixed to an upper part of the rod 5, and a tension adjusting spring 8 for pressing the cylinder 1 and the rod 5 in opposite directions is provided between the spring seat 6 and a flange 7 provided on the lower part of the outer periphery of the cylinder 1. It is built in.

On the lower surface of the spring seat 6, a cylindrical skirt 6a inserted into the tension adjusting spring 8 to prevent the upper part of the tension adjusting spring 8 from moving in the radial direction, and a push ring for pushing the retaining ring. A projection 6b is provided. On the other hand, a bulging portion 7a is provided on the upper surface of the flange 7 to prevent the lower end portion of the tension adjusting spring 8 from moving in the radial direction of the cylinder 1. The bulging portion 7a and the skirt 6a cause the tension adjusting spring 8 to move. Extend and contract without contacting the outer periphery of the cylinder 1.

A hydraulic damper 10 is incorporated in the cylinder 1 to buffer the pressing force when the cylinder 1 and the rod 5 are pressed in the direction of relative expansion and contraction.

The hydraulic damper 10 includes an insertion hole 14 into which the lower end of the rod 5 is inserted into a slidable plunger 13 that partitions the interior of the cylinder 1 into a pressure chamber 11 and a reservoir chamber 12, and the pressure chamber 11 and the reservoir chamber 12. Is formed, and a check valve 16 for preventing the hydraulic oil in the pressure chamber 11 from flowing into the reservoir chamber 12 is provided in the passage 15.

Reference numeral 17 denotes a perforated wear ring attached to the rod 5. The wear ring 17 is made non-movable in the axial direction by a shoulder 5a and a retaining ring 18 formed on the rod 5.

FIG. 3 shows an example of the use of the hydraulic auto tensioner having the above configuration. A spring seat 6 provided at the upper end of a rod 5 is connected to an engine block, and the cylinder 1
Is connected to one end of a pulley arm 21 that is swingably supported about a shaft 20. A tension pulley 22 is rotatably supported at the other end of the pulley arm 21, and the tension pulley 22 is pressed against the belt 23 by a pressing force of the tension adjusting spring 8 of the hydraulic auto tensioner pressing the pulley arm 21.

In a state where the hydraulic auto tensioner is used as described above, the tension of the belt 23 changes due to a change in torque, and when the tension of the belt 23 increases, the cylinder 1 is pressed upward via the pulley arm 21. .

At this time, since the pressure in the pressure chamber 11 becomes higher than that in the reservoir chamber 12, the check valve 16 is
And the upward pressing force applied to the cylinder 1 by the hydraulic oil sealed in the pressure chamber 11 is buffered.

When the pressing force for pressing the cylinder 1 is stronger than the elastic force of the tension adjusting spring 8, the hydraulic oil in the pressure chamber 11
Leakage occurs between the sliding surfaces of the cylinder 1 and the plunger 13 into the reservoir chamber 12, and the cylinder 1 slowly moves to a position where the elastic force of the tension adjusting spring 8 and the pressing force are balanced.

When the belt 23 becomes slack, the cylinder 1 moves downward by the elastic force of the tension adjusting spring 8, and the pulley arm 21 swings in the direction in which the tension pulley 22 stretches the belt 23.

At this time, since the pressure in the pressure chamber 11 becomes lower than the pressure in the reservoir chamber 12, the check valve 16 opens the passage 15, and the hydraulic oil in the reservoir chamber 12 flows from the passage 15 to the pressure chamber 11. For this reason, the cylinder 1 descends rapidly, and the tension pulley 22 swings rapidly in the direction of stretching the belt 23 to immediately absorb the slack of the belt 23.

When assembling the hydraulic auto tensioner, the plunger 13 is placed in the cylinder 1 filled with hydraulic oil.
And the like, and a tension adjusting spring 8 is inserted outside the cylinder 1.

Next, as shown in FIG.
From the lower end of the rod 5 to which is fixed, the chrysanthemum-shaped retaining ring 4 and the oil seal 2 are inserted, as shown in FIG.
The chrysanthemum-shaped retaining ring 4 is brought into contact with the lower end of the protruding portion 6b, and the wear ring 17 is inserted and retained by attaching the retaining ring 18, and the rod 5 is inserted into the cylinder 1 from above.

With the insertion of the rod 5, the wear ring 17 is inserted into the cylinder 1, and the spring seat 6 comes into contact with the upper end of the tension adjusting spring 8 during the insertion. When the spring seat 6 is pressed against the elasticity of the tension adjusting spring 8 from this contact state, the oil seal 2 is inserted into the cylinder 1 and, as shown in FIG. An engaging piece 4c contacts the opening end of the cylinder 1 on the outer circumference of the cylinder. The engagement piece 4c has a protrusion 6b of the spring seat 6 and
Is pressed upward, and the chrysanthemum retaining ring 4 is inserted into the cylinder 1 by the deformation.

When the retaining ring 4 is inserted to the position of the engagement groove 3, the engagement piece 4c engages with the engagement groove 3, and the engagement prevents the oil seal 2 from coming off, thereby assembling the auto tensioner. Is completed.

When the pressing of the spring seat 6 is released after assembling the auto tensioner, the spring seat 6 and the rod 5 are pulled upward by the elastic force of the tension adjusting spring 8, and FIG.
As shown in FIG. 7, the wear ring 17 comes into contact with the oil seal 2 and is prevented from falling off.

FIGS. 6 (I) and (II) show another example of the hydraulic auto-tensioner according to the present invention. The hydraulic auto tensioner shown in this example is different from the hydraulic auto tensioner shown in FIG. 1 described above in that a tension adjusting spring 8 is incorporated in the cylinder 1. Since other configurations are the same, the same components are denoted by the same reference numerals and description thereof will be omitted.

When assembling the hydraulic auto-tensioner with a spring inside shown in FIG. 6, after inserting hydraulic components such as a plunger and various components such as a tension adjusting spring 8 into the cylinder 1, FIG. As shown, the wear ring 17, the oil seal 2, and the chrysanthemum retaining ring 4 are attached to the rod 5, and after the rod 5 is inserted into the cylinder 1, the chrysanthemum retaining ring 4 is pushed in the axial direction, and The engagement piece 4 c on the outer periphery of the wheel 4 is engaged with the engagement groove 3.

[0034]

As described above, in the present invention, a chrysanthemum retaining ring and an oil seal are inserted into a rod fixed to a spring seat, and the rod is inserted into a cylinder to press the spring seat. Since the engagement piece on the outer periphery of the chrysanthemum-shaped retaining ring engages with the engagement groove provided on the inner periphery of the opening of the cylinder to prevent the oil seal from coming off, the auto tensioner can be assembled very easily.

Further, by bending the engaging piece on the outer periphery of the chrysanthemum-shaped retaining ring to one side, the chrysanthemum-shaped retaining ring can be easily inserted into the inner periphery of the opening of the cylinder, and the stopper for the engaging groove can be prevented. The engagement force of the wheel in the retaining direction is strong, and the oil seal can be reliably retained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of an auto tensioner according to the present invention.

FIG. 2 (I) is a plan view of the same chrysanthemum retaining ring, and FIG. 2 (II) is a cross-sectional view.

FIG. 3 is a front view showing a use state of the auto tensioner according to the first embodiment;

FIG. 4 (I) is a sectional view showing a state before a retaining ring and an oil seal are attached to a rod, and (II) is a sectional view showing an assembled state.

FIG. 5 (I) is a cross-sectional view showing a state during insertion of a rod into a cylinder, and (II) is a cross-sectional view showing a state after insertion.

FIG. 6 (I) is a longitudinal sectional front view showing another example of the auto tensioner according to the present invention, and FIG. 6 (II) is a sectional view showing a state in which the auto tensioner is being assembled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Oil seal 3 Engagement groove 4 Retaining ring 4b Rod insertion hole 4c Engagement piece 5 Rod 6 Spring seat 6b Projection 8 Tension adjustment spring 10 Hydraulic damper

Claims (5)

[Claims] An engaging groove is formed in the inner periphery of an upper opening of a cylinder filled with hydraulic oil, and a retaining ring engaged with the engaging groove prevents an oil seal sealing the opening from coming off. Then, the elastic force of the tension adjusting spring is applied to the rod that slidably penetrates the oil seal to press the rod and the cylinder in opposite directions, and the rod and the cylinder are pressed in the direction of relatively contracting. In a hydraulic auto tensioner in which the pushing force at the time is buffered by a hydraulic damper provided inside the cylinder, the retaining ring has a rod insertion hole as a center and can be engaged with the engagement groove on an outer peripheral portion. A plurality of engagement pieces formed in a chrysanthemum-shaped retaining ring. 2. The hydraulic auto-tensioner according to claim 1, wherein the engagement piece is bent toward one side of the retaining ring to be inclined. 3. The tension adjusting spring is provided outside the cylinder, and a spring seat receiving an elastic force of the tension adjusting spring is mounted on an upper portion of the rod.
The hydraulic auto tensioner according to 1. 4. The hydraulic automatic tensioner according to claim 3, wherein a projection for pushing the chrysanthemum-shaped retaining ring is provided on a lower surface of the spring seat. 5. A belt for driving an engine auxiliary machine, wherein the adjusting force of the hydraulic auto-tensioner according to claim 1 is applied to maintain a constant belt tension. Belt tension adjustment device.