JPH11148540A - Hydraulic automatic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the spring force without changing the length or the inside diameter of a cylinder by providing a return spring to urge a rod in a direction to press a pulley arm outside the cylinder. SOLUTION: A return spring 17 is provided outside a cylinder 11, one end of which is supported by a flange 25 at a lower part of an outer circumference of the cylinder 11, the other end of which is received by a spring seat 26 at a tip part of a rod 15, and a spring seat 26 is pressed to provide the outwardly projecting property. Thus, the return spring 17 is less subjected to the limitation of the length, and the return spring 17 which is large in total length and large in spring force can be assembled. The spring force of the return spring 17 can be largely without changing the inside diameter of the cylinder so as to be sufficiently adaptable to the required belt tension. Even when the return spring 17 with a large set value of the spring force is required, the length or the inside diameter of the cylinder 11 need not be increased, and the quantity of the working fluid is increased.

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 used for adjusting the tension of an engine timing belt and the like.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic auto-tensioner which realizes a lighter cylinder, as shown in FIG. 2, a separate sleeve 2 'is provided inside a cylinder 1' made of a light alloy, ', A piston 3 is slidably inserted inside.

In this structure, the hydraulic oil chamber 4 inside the cylinder 1 'is divided into a pressure chamber 5 and a reservoir chamber 6 by a piston 3, and a passage 7 for communicating the pressure chamber 5 and the reservoir chamber 6 is provided in the piston 3. A check valve 8 for opening and closing the passage 7 is provided at the outlet of the passage.

Further, a piston rod 9 is connected to the piston 3, and a step 11 formed on the piston rod 9 is engaged with a bearing 11 which slides on the inner peripheral surface of the cylinder 1 '. A return spring 12 'is incorporated between the upper end of 2' and the piston 3 and the piston rod 9 to apply a spring force in a direction of projecting outward.

In the drawing, 13 is a retainer, 14 is a spring for connecting the piston 3 and the piston rod 9, 15 is an oil seal, 16 is a tension pulley, 17 is a support arm thereof, 18 is a support shaft, and 19 is a tension adjustment. It is a belt.

[0006]

In the hydraulic auto tensioner having the above structure, the adjustment of the belt tension is performed by changing the spring force of the return spring 12 ', but the spring force of the return spring 12' is increased. In order to achieve this, it is necessary to employ either a method of increasing the overall length of the spring 12 'or an increase in the spring constant.

However, in the conventional auto-tensioner shown in FIG. 2, since the return spring 12 'is incorporated between the sleeve 2' and the bearing 11, when the total length of the return spring 12 'is increased, the cylinder 1' Has a problem in that the overall length of the motor becomes large as it is, and it becomes difficult to mount it on an engine or the like.

On the other hand, in order to suppress an increase in cylinder length,
When the spring constant of the return spring 12 'is increased, it is difficult to bring the spring force of the entire return spring into a predetermined range, and it is difficult to make the spring force match the required belt tension.

Accordingly, an object of the present invention is to provide a structure capable of setting a large spring force of a return spring without increasing a cylinder length or changing a spring constant.

[0010]

In order to solve the above-mentioned problems, the present invention has a return spring fitted on the outside of a cylinder.

[0011]

In the above structure, since the cylinder and the return spring overlap in the length direction, only the entire length of the spring can be increased without increasing the cylinder length.

Further, since the spring length can be increased,
The spring force can be set large without changing the spring constant.

[0013]

FIG. 1 shows a hydraulic auto-tensioner according to an embodiment. Since the basic structure of this auto tensioner is the same as that of the conventional one shown in FIG. 2, the same parts are denoted by the same reference numerals and description thereof will be omitted.

The difference of this embodiment from the conventional one is that
The point is that a return spring 12 is fitted to the outside of the outer peripheral surface of the cylinder 1.

That is, the return spring 12 is formed by a coil spring wound around the outer peripheral surface of the cylinder 1 with a gap, and one end of the return spring 12 is engaged with a flange 20 provided on the outer peripheral bottom of the cylinder 1.

A spring seat 21 is mounted on the peripheral surface of the piston rod 9 so as to extend outward from the outer periphery of the cylinder 1.
The other end of the return spring 12 is engaged with the spring seat 21, so that the piston rod 9 is always provided with a spring force in a direction of projecting outward.

In the above structure, since the cylinder 1 and the return spring 12 overlap in the length direction, the entire length of the return spring 12 can be increased without increasing the cylinder length, and the spring force can be set large. it can.

Further, since the entire length of the return spring 12 can be increased, it is possible to increase the spring force of the entire spring without changing or reducing the spring constant. Therefore, the spring force of the spring is
It can be exactly matched to the required belt tension.

Further, since the return spring 12 is provided outside the cylinder 1, the inner diameter of the cylinder 1 and the volume of the hydraulic oil chamber 4 can be made the same as those of the conventional structure shown in FIG. Therefore, there is no increase in the amount of hydraulic oil, and parts such as the sleeve 2, the piston 3, and the bearing 11 can be shared with conventional parts.

In the auto tensioner having the above structure,
When the tension of the belt 19 increases, the tension pulley 16
Swings, and the pressing force acting on the piston rod 9 increases. As a result, when the piston 3 is pushed, the hydraulic oil in the pressure chamber 5 leaks from the gap between the piston 3 and the cylinder 1 to the reservoir chamber 6 to buffer the movement of the piston 3. For this reason, the tension pulley 16 swings slowly and responds to an increase in belt tension.

Conversely, when the tension of the belt 19 decreases, the piston rod 9 protrudes outward by the spring force of the return spring 12, and when the piston 3 rises following this movement, the pressure in the pressure chamber 5 decreases, Check valve 8
Opens the passage 7. For this reason, the hydraulic oil in the reservoir chamber 6 moves to the pressure chamber 5 through the passage 7 and the piston rod 9
Protrudes rapidly and swings the tension pulley 16 in accordance with the movement of the belt. At this time, the piston 3 stops at the balance point between the pressing force acting on the piston rod 9 and the spring force of the return spring 12.

In the above embodiment, the sleeve 2 is provided inside the cylinder 1, but the sleeve 2 may be omitted and the piston 3 may be slid directly on the inner peripheral surface of the cylinder.

[0023]

As described above, according to the present invention, since the return spring is fitted to the outside of the cylinder and both are overlapped in the length direction, only the entire length of the return spring is increased without increasing the cylinder length. The spring force can be increased with a compact shape.

Also, since the total length of the return spring can be increased, the spring force can be set large without changing the spring constant or with a small spring constant, and the spring force of the spring can be accurately adjusted. There are advantages.

Further, since it is not necessary to increase the inner diameter of the cylinder, the volume of the hydraulic oil chamber does not increase, and in addition, the internal parts such as the piston can be shared with those of the conventional structure.
There is an advantage that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Sleeve 3 Piston 4 Hydraulic oil chamber 9 Piston rod 12 Return spring 20 Flange 21 Spring seat

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[Procedure amendment]

[Submission date] August 11, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Belt tension adjusting device

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tension adjusting device for maintaining a constant tension of a belt such as an engine timing belt.

[0002]

2. Description of the Related Art A belt tension adjusting device as shown in FIG. 2 has been proposed. In this belt tension adjusting device, a tension pulley 3 is rotatably attached to a tip end of a pulley arm 2 supported swingably about a support shaft 1, and a hydraulic auto tensioner 1 is attached to the pulley arm 2.
The tension pulley 3 is pressed against the belt 4 by applying an adjusting force of zero.

Here, the hydraulic auto tensioner 10 is
A sleeve 12 made of light alloy is provided at the bottom of the cylinder 11.
The hydraulic oil is poured into the sleeve 12 and the cylinder 11, and the hydraulic oil is prevented from leaking outside by the oil seal 13 attached to the upper opening of the cylinder 11.

[0004] A piston 14 is provided in the sleeve 12.
Is slidably inserted, and a rod 15 whose lower part is connected to a piston 14 is swingably inserted into a rod insertion hole 13 a provided in the oil seal 13, and a wear ring 16 fitted to the rod 15 is inserted. And the sleeve 1
The wear ring 16 is pressed against a stepped portion 18 provided on the outer periphery of the rod 15 by incorporating a return spring 17 between the rod 15 and the outer spring 2 to give the rod 15 a protruding outward property.

Further, a piston 14 has a pressure chamber 19 provided below and a reservoir chamber 20 provided above.
And a check valve 22 that closes the passage 21 when the pressure in the pressure chamber 19 becomes higher than the pressure in the reservoir chamber 20.

In the drawing, reference numeral 23 denotes a retainer, and reference numeral 24 denotes a spring for connecting the piston 14 and the rod 15.

In the belt tension adjusting device having the above structure, when the tension of the belt 4 increases, the rod 15
Is pushed in, and the piston 14 compresses the hydraulic oil in the pressure chamber 19. At this time, since the check valve 22 closes the passage 21, a change in the tension of the belt 4 is absorbed by the hydraulic oil in the pressure chamber 19.

The tension of the belt 4 is reduced by the return spring 17.
Is greater than the spring force, the hydraulic oil in the pressure chamber 19 flows from between the sliding surfaces of the piston 14 and the sleeve 12 to the reservoir chamber 2.
0, the piston 14 moves slowly to the pressure chamber 19 side, and the spring force of the return spring 17 and the belt 4
The piston 14 stops at the position where the tension of the piston 14 is balanced.

On the other hand, when the belt 4 is slackened, the rod 15 moves outward by the spring force of the return spring 17. At this time, the check valve 22 is
The hydraulic oil in the reservoir chamber 20 flows through the passage 2
From 1 to the pressure chamber 19 smoothly, the rod 15 moves outward rapidly and absorbs the slack of the belt 4 immediately.

As described above, the hydraulic auto tensioner 10
The rod 15 moves backward slowly when the tension of the belt 4 increases, and moves quickly outward when the tension decreases.
Can be satisfactorily followed, and the tension of the belt 4 can always be kept constant.

Further, in the hydraulic auto tensioner 10, since the upper opening of the cylinder 11 is sealed by the oil seal 13, there is no leakage of the hydraulic oil to the outside, and the deterioration of the belt 4 due to the adhesion of the hydraulic oil is ensured. The feature is that it can be prevented.

In the belt tension adjusting device having the above structure, the static tension of the belt 4 is controlled by the return spring 1.
If the return spring 17 is determined by the spring force of 7 and the set value of the spring force is required, it is necessary to use the return spring 17 having a long overall length or the return spring 17 having a large spring constant.

[0013]

In the belt tension adjusting device shown in FIG. 2, since the return spring 17 is incorporated in the cylinder 11, when the return spring 17 having a long overall length is used, the cylinder 11
It is necessary to increase the overall length of the automatic tensioner, so that an auto tensioner cannot be mounted around the engine.

On the other hand, when the return spring 17 having a large spring constant is used, the inner diameter of the cylinder 11 becomes large, and it is necessary to newly manufacture the piston 14 and the wear ring 16 in accordance with the inner diameter of the cylinder, and the amount of hydraulic oil is reduced. Increase the weight and increase the weight.

An object of the present invention is to provide a belt tension adjusting device capable of setting a large spring force of a return spring without changing a cylinder length or a cylinder inner diameter.

[0016]

In order to solve the above-mentioned problems, in the present invention, an adjusting force of a hydraulic auto-tensioner is applied to a swingable pulley arm that supports a tension pulley, and the tension pulley is moved to a belt. The hydraulic auto-tensioner is pressurized, and the hydraulic oil is sealed inside by the installation of an oil seal, and the hydraulic oil is sealed inside. A rod connected to the piston and slidably penetrating the oil seal; and a return spring for urging the rod in a direction in which the rod presses the pulley arm. And a passage is formed in the piston to communicate the pressure chamber and the reservoir chamber, In a belt tension adjusting device comprising a closed hydraulic auto-tensioner provided with a check valve that closes the passage when the pressure of the pressure chamber becomes higher than the pressure of the reservoir chamber, the return spring is provided outside the cylinder. The configuration provided is adopted.

With the above configuration, the length of the return spring is less restricted, and the spring force of the return spring can be set large without changing the cylinder length or the cylinder inner diameter.

[0018]

An embodiment of the present invention will be described below with reference to FIG.

The belt tension adjusting device shown in FIG. 2 differs from the conventional belt tension adjusting device shown in FIG. 2 only in the position at which the return spring 17 is incorporated. The same components as those of the apparatus are denoted by the same reference numerals, and description thereof will be omitted.

The return spring 17 is provided outside the cylinder 11, one end of which is supported by a flange 25 provided at the lower part of the outer periphery of the cylinder 11, and the other end of which is a spring seat 26 attached to the tip of the rod 15. When received, the spring seat 26 is pressed, and the rod 15 is given an outward projecting property.

The operation of the belt tension adjusting device having the above-described configuration is the same as the operation of the belt tension adjusting device shown in FIG.

By providing the return spring 17 outside the cylinder 11 as described above, the length of the return spring 17 is less restricted, and the return spring 17 having a long overall length and a large spring force can be incorporated. Can be possible.

For this reason, the spring force of the return spring can be set large without changing the inner diameter of the cylinder, so that the required belt tension can be sufficiently coped with.

Further, even if the return spring 17 having a large set value of the spring force is required, it is not necessary to increase the length and the inner diameter of the cylinder 11, so that the amount of the working oil does not increase.
Interior parts such as the sleeve 12, the piston 14, the wear ring 16 and the like incorporated in the cylinder 11 can be shared with conventional ones.

Although the sleeve 12 is provided inside the cylinder 11 in the embodiment, the sleeve 12 may be omitted, and the piston 14 may be slid along the inner peripheral surface of the cylinder 11.

[0026]

As described above, according to the present invention, since the return spring is provided outside the cylinder, the length of the return spring is increased without changing the length or the inner diameter of the cylinder, and the spring force is increased. Can be increased, and it is possible to sufficiently cope with the required belt tension.

Further, since it is not necessary to increase the length and inner diameter of the cylinder, it is possible to prevent an increase in the amount of hydraulic oil, suppress an increase in the weight of the hydraulic auto-tensioner, and make the interior parts such as the piston of a conventional structure. Since this can be used in common, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a corrugated board showing an embodiment of a belt tension adjusting device according to the present invention.

FIG. 2 is a sectional view showing a conventional belt tension adjusting device.

[Description of Signs] 2 Pulley arm 3 Tension pulley 4 Belt 10 Hydraulic auto tensioner 11 Cylinder 13 Oil seal 14 Piston 15 Rod 17 Return spring 19 Pressure chamber 20 Reservoir chamber 21 Passage 22 Check valve

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

Claims (1)

[Claims] 1. A hydraulic oil chamber in a cylinder is divided into a pressure chamber and a reservoir chamber by a piston slidably inserted into the cylinder, and a passage communicating between the pressure chamber and the reservoir chamber is formed in the piston. At the same time, a check valve for closing the passage when the hydraulic oil pressure on the pressure chamber side is higher than the reservoir chamber is provided in the passage, and a spring force in a direction protruding outside the cylinder is applied to the piston rod connected to the piston. In a hydraulic auto tensioner to which a return spring to be applied is connected, the return spring is fitted on the outside of a cylinder.