JP2001208153A - Hydraulic automatic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic automatic tensioner capable of making component members of a hydraulic damper as a cassette to improve assembling efficiency, reducing a pressure chamber to raise the damper effect, and satisfying the requirements for both compactness and long stroke. SOLUTION: In this hydraulic automatic tensioner having the hydraulic damper 1 stored in a tension pulley shed, a plunger spring 11 energizing a rod 7 through a plunger 4 is stored in a reservoir chamber 5, the plunger spring 11 is a tension coil spring having one end locked in the plunger 4 and the other end locked in a wearing 10 to make the component members of the hydraulic damper 1 as a cassette.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-tensioner used for adjusting the tension of a timing belt of an automobile, and more particularly to a hydraulic auto-tensioner having improved assemblability, being compact, and capable of having a long stroke.

[0002]

2. Description of the Related Art The applicant of the present invention has proposed a hydraulic auto-tensioner in which the size of a hydraulic damper can be accommodated in the umbrella of a tension pulley and the clearance between an engine block and the tension pulley can be reduced. Has already been proposed in Japanese Patent No. 2813162.

FIGS. 4 to 6 show the structure of the above-mentioned hydraulic auto-tensioner. A tension pulley 21 is mounted so as to be rotatable around an eccentric wheel 23 via a rolling bearing 22 and provided on the eccentric wheel 23. Slide the eccentric hole 24 into the bearing 2
A fixing bolt 26 that penetrates through the pin 5 is fastened to the engine block 27, and a hydraulic damper 28 is disposed between the eccentric wheel 23 and the opposing surface of the engine block 27 so as to fit inside the umbrella of the tension pulley 21.

As shown in FIG. 5, the hydraulic damper 28 accommodates a plunger 31 movably in the axial direction in a liquid chamber 30 in an oblique vertical direction provided in a damper cylinder 29, and one side of the damper cylinder 29. Projection 32 coupled to the part
In addition, a sub-reservoir chamber 33 and a mounting portion 34 are provided above the sub-reservoir chamber 33.

The plunger 31 communicates with a pressure chamber 36 formed at the lower end of the liquid chamber 30 through a passage 37 at the lower end of a reservoir chamber 35 provided inside the plunger 31 along the axis. A check valve 38 and a pressure chamber 3
A plunger spring 39 using a compression coil spring for returning the plunger 31 is contracted in 6.

A peripheral groove 40 communicating with the reservoir chamber 35 is provided on the outer peripheral surface of the intermediate portion of the plunger 31, and the sub-reservoir chamber 3 is provided.
3 is provided at a right angle to the liquid chamber 30, communicates with the circumferential groove 40 through the passage 41, and the open end of the sub-reservoir chamber 33 is in close contact with the rubber cap 42.

The plunger 31 has a head 4 at its upper end.
3, the upper end of the reservoir chamber 35 is sealed by an O-ring 44, and the upper end of the liquid chamber 30 is sealed by an oil seal 45.

The hydraulic damper 28 has a reservoir chamber 35.
And an amount of hydraulic oil that fills the entire pressure chamber 36 and a part of the sub-reservoir chamber 33 is filled.
3 is arranged so that the upper side space becomes an air chamber.

As shown in FIGS. 4B and 5, the hydraulic damper 2
8, the fixing bolt 26 penetrates the mounting portion 34, and the fixing pin 46 penetrating the protrusion 32 is fixed to the engine block 27, so that the sub reservoir chamber 33 is arranged obliquely upward. The hydraulic oil is set to such an amount that the oil level does not contact the rubber cap 42 while leaving an air space above the sub reservoir chamber 33,
The head 43 of the plunger 31 is in contact with a pin 47 projecting from the eccentric wheel 23.

The hydraulic damper 28 is provided with a sub-reservoir chamber 33 on the side of the liquid chamber 30 so that a plunger 31 is provided.
The entire length of the portion can be shortened, so that the entire hydraulic damper 28 can be reduced in size and housed in the umbrella of the tension pulley 21, and the gap W ₁ between the tension pulley 21 and the engine block 27 can be reduced. Can be.

On the other hand, as shown in FIG. 6, the eccentric ring 23 for supporting the tension pulley 21 is provided with a window hole 48 into which a fixing pin 46 is loosely fitted. In the hole 49, a tension adjusting spring 51 whose tip abuts on the fixing pin 46 via the spring seat 50 is contracted, and the eccentric wheel 23 applies a rotational force in the tension direction of the belt A with the fixing bolt 26 as a fulcrum. I'm going.

When the tension of the belt A increases in the state shown in FIG.
The eccentric wheel 23 rotates counterclockwise in FIG. 3 with the fixing bolt 26 as a fulcrum, and the plunger 31 is pushed by the pin 47.

When the plunger 31 is pushed in, the pressure chamber 3
The hydraulic oil in 6 moves from the leak gap between the plunger 31 and the inner peripheral surface of the liquid chamber 30 to the peripheral groove 40 to buffer the operation of the plunger 31. The hydraulic oil that has moved to the circumferential groove 40 is
1 enters the sub reservoir chamber 33.

The plunger 31 stops at the balance point between the tension of the belt A and the spring force of the tension adjusting spring 51.

On the other hand, when the tension of the belt A decreases, the tension pulley 21 and the eccentric wheel 23 rotate clockwise in FIG. 2 and the swing of the tension pulley 21 at the balance point between the tension adjusting spring 51 and the tension of the belt A. Motion stops.

At this time, since the pin 47 of the eccentric wheel 23 moves away from the plunger 31, the plunger 3
1 is a pin 4 which is pressed by the return coil spring 39.
7 follows the movement of 7 and rises.

In this case, since the check valve 38 opens the communication passage 37, the hydraulic oil in the reservoir chamber 35 is released from the pressure chamber 36.
And the working oil in the sub reservoir chamber 33 flows into the reservoir chamber 35, and the plunger 31 immediately follows the movement of the pin 47.

[0018]

By the way, the above-mentioned hydraulic damper 7 includes a damper cylinder 29, a plunger 31,
Since the components such as the check valve 38, the plunger spring 39, and the oil seal 45 are separated and independent from each other, the assemblability of the hydraulic damper is poor, and
Plunger spring 3 for returning plunger 31
9, a compression coil spring is used, and the compression coil spring is housed in the pressure chamber 36. Therefore, the pressure chamber becomes large and the damper effect is reduced. There was room for improvement in that it was not possible to satisfy both.

Therefore, an object of the present invention is to make a component of the hydraulic damper into a cassette, thereby improving the assemblability of the hydraulic damper, and increasing the damper effect by reducing the size of the pressure chamber. It is an object of the present invention to provide a hydraulic auto-tensioner capable of satisfying both demands for longer stroke and longer stroke.

[0020]

In order to solve the above-mentioned problems, the invention of claim 1 applies a spring force of a tension adjusting spring to an eccentric wheel of a tension pulley, and rotates the eccentric wheel when the belt tension increases. The hydraulic damper formed by engaging the rod with a part of the eccentric ring and buffering a check valve located between the pressure chamber and the reservoir chamber in the damper cylinder was housed in the tension pulley umbrella. In a hydraulic auto-tensioner, a plunger spring for urging the rod through a plunger is housed in the reservoir chamber, and one end of the plunger spring is engaged with the plunger and the other end is engaged with a wear ring. Is adopted.

According to a second aspect of the present invention, in the first aspect, the rod and the plunger are integrally formed.

According to a third aspect of the present invention, in the first or second aspect, a washer is fitted to the plunger, and the tension coil spring is locked to the washer.

According to a fourth aspect of the present invention, in the first to third aspects, the locking end of the tension coil spring is swaged.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the locking ends of the tension coil springs are configured to have 180 degrees different directions.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The basic structure of the hydraulic auto-tensioner is the same as that described in the related art with reference to FIGS. 4 to 6, and therefore, the same portions are denoted by the same reference characters or used in the description. Substitute.

Referring to FIGS. 1 to 3, a hydraulic damper 1 according to the present invention includes a vertical liquid chamber 3 provided in a damper cylinder 2.
The plunger 4 is accommodated in the inside so as to be movable in the axial direction, and the protrusion 3 coupled to one side of the damper cylinder 2 is provided.
2, a sub-reservoir chamber 33 and a mounting portion 34 are provided above the sub-reservoir chamber 33.

The plunger 4 partitions the inside of the liquid chamber 3 up and down, so that the reservoir chamber 5 is located at the upper part and the pressure chamber 6 is located at the lower part.
A rod 7 is integrally provided on the upper part of the plunger 4, and the upper end of a passage 8 provided inside along the axis of the plunger 4 is opened to the outside at the root of the rod 7 to form a reservoir chamber. The lower end of the passage 8 communicates with the pressure chamber 6 via a check valve 38.

A washer 9 is fitted to the plunger 4 so as to move integrally with the plunger 4 in the axial direction at the root of the rod 7, and the wear ring 1 is provided in the middle of the rod 7.
0 is mounted so as to be movable in the axial direction, and between the washer 9 and the wear ring 10 is provided a plunger spring 11 having one end fixed to the washer 9 of the plunger 4 and the other end fixed to the wear ring 10, respectively. Reference numeral 11 is formed of a tension coil spring that constantly pulls the washer 9 and the wear ring 10. In the following description, the plunger spring 11 is referred to as a tension coil spring.

The washer 9 of the tension coil spring 11
And the engagement ends of the tension coil springs with respect to the washer 9 and the wear ring 10 are set so as to be 180 degrees different from each other. ing.

As shown in FIG. 2, a rod 7 is provided integrally with the plunger 4, and a washer 9 attached to the base of the rod 7 so as to move integrally with the plunger 4, and the rod 7 can be moved in the axial direction. Wear ring 10 inserted
By incorporating the tension coil spring 11 between
These members can be combined into one to form a cassette, and the assemblability of the hydraulic damper 1 is improved.

By incorporating the plunger 4 into the liquid chamber 3, the tension coil spring 11 is accommodated in the reservoir chamber 5, and the wear ring 10 is accommodated in a step provided on the upper inner periphery of the damper cylinder 2. An oil seal 45 sealing the upper end of the reservoir chamber 5 is fixed on the retainer, and the rod 7 penetrates the oil seal 45 in a watertight manner so as to be movable in the axial direction.

Here, the plunger 4 is made of SCr42.
It is formed by carburizing and quenching case hardening steel such as 0, or sub-hardening high carbon chromium steel such as SUJ2.
The damper cylinder 2 is made of medium carbon steel such as S55C and processed by means such as forging, turning, and grinding.

The material of the tension coil spring 11 is SWO in consideration of set in a conventional compression spring.
Although SC (valve spring steel) is used, in the present invention, the storage space is increased by incorporating the washer 9 and the wear ring 10 in the reservoir chamber 5, so that the normal SWPB (spring steel) is used. Can be used.

The hydraulic auto-tensioner according to the present invention has the above-described configuration. FIG. 1A shows a state in which the plunger 4 is pushed most through the rod 7 in the hydraulic damper 1. 1 (B) shows a state in which the rod 7 projects most.

As shown in FIG. 3, when the tension of the belt A increases, the tension pulley 21 and the eccentric wheel 23 rotate counterclockwise in FIG. 3 with the fixing bolt 26 as a fulcrum. The plunger 4 is pushed.

When the plunger 4 is pushed in, the hydraulic oil in the pressure chamber 6 moves from the leak gap between the plunger 4 and the inner peripheral surface of the liquid chamber 3 to the reservoir chamber 5 to buffer the operation of the plunger 4. At this time, the tension coil spring 11 is extended.

The plunger 4 stops at the balance point between the tension of the belt A and the spring force of the tension adjusting spring 51.

On the other hand, when the tension of the belt A decreases, the tension pulley 21 and the eccentric wheel 23 rotate clockwise in FIG. 3, and the swing of the tension pulley 21 at the balance point between the tension adjusting spring 51 and the tension of the belt A. Motion stops.

At this time, the pin 47 of the eccentric wheel 23 moves in a direction away from the rod 7, and the rod 7 and the plunger 4 are separated by the tension of the tension coil spring 11.
7 follows the movement of 7 and rises.

In this case, since the check valve 38 opens the passage 8, the hydraulic oil in the reservoir chamber 5 flows into the pressure chamber 6, and the hydraulic oil in the sub-reservoir chamber 33 flows into the reservoir chamber 5. The rod 7 and the plunger 4 immediately follow the movement of the pin 47.

[0041]

As described above, according to the present invention, in a hydraulic auto tensioner in which a hydraulic damper is reduced in size and accommodated in an umbrella of a tension pulley, a plunger spring for urging a rod via a plunger is provided. Since the tension coil spring is housed in the reservoir chamber and one end of the plunger spring is fixed to the plunger and the other end is fixed to the wear ring, the rod, the plunger, and the tension coil spring, which are the components of the hydraulic damper, are connected to the cassette. In addition, the ease of assembling the hydraulic damper is improved, and the tension coil spring is housed in the reservoir chamber to reduce the pressure chamber and improve the damper effect. Both requirements can be met.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view showing a state in which a plunger is pushed most through a rod in a hydraulic damper of the present invention, and FIG. 1B is a longitudinal sectional view showing a state in which a rod projects most.

FIG. 2 is an exploded longitudinal sectional view showing the structure of the hydraulic damper in the above.

FIG. 3 is a longitudinal sectional view of a hydraulic auto tensioner using a hydraulic damper in the above.

FIG. 4 (a) is a vertical sectional front view showing a prior art auto tensioner, and FIG. 4 (b) is a vertical sectional side view.

FIG. 5 is a longitudinal sectional front view showing a structure of a hydraulic damper part according to the first embodiment;

FIG. 6 is a longitudinal sectional front view showing a structure of an eccentric ring portion of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic damper 2 Damper cylinder 3 Liquid chamber 4 Plunger 5 Reservoir chamber 6 Pressure chamber 7 Rod 8 Passage 9 Washer 10 Wearing 11 Plunger spring 21 Tension pulley 23 Eccentric wheel 26 Fixing bolt 27 Engine block 33 Secondary reservoir chamber 38 Check valve 46 Fixing Pin 47 Pin 51 Spring for tension adjustment

Claims (5)

[Claims] The present invention provides a spring force of a tension adjusting spring applied to an eccentric wheel of a tension pulley, and a rod is engaged with a part of the eccentric wheel so as to buffer rotation of the eccentric wheel when the tension of the belt is increased. In a hydraulic auto tensioner in which a hydraulic damper formed by providing a check valve located between a pressure chamber and a reservoir chamber in a cylinder is housed in a tension pulley umbrella, a plunger spring for urging the rod through a plunger is provided. , While being housed in the reservoir chamber, one end of the plunger spring is
A hydraulic auto tensioner wherein the other ends are tension coil springs respectively locked to a wear ring. 2. The hydraulic auto tensioner according to claim 1, wherein the rod and the plunger are formed integrally. 3. The hydraulic auto tensioner according to claim 1, wherein a washer is fitted to the plunger, and the tension coil spring is locked to the washer. 4. The hydraulic auto tensioner according to claim 1, wherein a locking end of the tension coil spring is swaged. 5. The locking end of the tension coil spring is 18
The hydraulic auto tensioner according to any one of claims 1 to 4, wherein the direction of the hydraulic auto tensioner is 0 degrees.