JPH06249308A - Auto-tensioner - Google Patents

Abstract

PURPOSE:To apply an auto-tensioner even in a layout where a gap between an engine block and a pulley part is very small, in the auto-tensioner consisting of an actuator part and the pulley part. CONSTITUTION:The spindle 31 of a pulley part 12 is supported by an arm 13 provided at the tip of a push rod 22 in such a way that the center line of a push rod 22, going back and forth in relation to the spring force of a tension adjusting spring 25 stored in an actuator part 11 and the tension of a belt 33 may stay on the central face S in the width direction of the pulley part 12.

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 to apply a constant tension to a timing belt of an automobile engine.

[0002]

2. Description of the Related Art As an actuator for applying a constant tension to a timing belt of an automobile engine, it comprises an actuator portion 1 and a pulley portion 2 as shown in FIG.
It is well known that a tension adjusting spring is housed inside a cylinder that constitutes the actuator section 1 and the spring force is applied to the pulley section 2 via a push rod inserted into the cylinder. .

Further, a hydraulic damper is provided at the inner bottom of the cylinder, one end of the push rod is integrated with a piston constituting the damper, and the damper is made to act when the push rod 3 is pushed in. On the contrary, it is conventionally known that the generation of vibration of the belt 4 is suppressed by providing a directionality in which the push rod 3 does not act in the protruding direction.

The autotensioner as described above is mounted by fixing the actuator section 1 to the engine block 6 with bolts 5 and the pulley section 2 to the engine block 6 with bolts 7. The push rod 3 of the actuator unit 1 is brought into contact with the arm 8 of the pulley unit 2 and swings the pulley unit 2 via the arm 8.

[0005]

According to the conventional automatic tensioner as described above, the width of the actuator portion 1 is included in the gap g between the engine block 6 and the pulley portion 2.

Therefore, when the above-mentioned gap g is very small in view of the layout of parts near the engine, it becomes difficult to adopt the above-mentioned auto tensioner.

Therefore, according to the present invention, by adopting a structure in which the width of the actuator portion is not included in the gap g,
An object of the present invention is to provide an auto tensioner that can be used even in the case of a layout in which the gap g is very small.

[0008]

In order to solve the above-mentioned problems, the present invention comprises an actuator portion and a pulley portion, and a tension adjusting spring is housed inside a cylinder constituting the actuator portion. In an auto tensioner configured to apply a spring force to the pulley portion via a push rod inserted in the cylinder, an arm provided at the tip of the push rod fixes the spindle of the pulley, and the center of the push rod is fixed. The line is substantially positioned on the center plane of the pulley in the width direction.

[0009]

[Function] When the above actuator is attached to a fixed body such as an engine block and the pulley is pressed against the belt,
The push rod moves back and forth according to the tension of the belt, and stops when the spring force of the tension adjusting spring and the tension of the belt are balanced. Since the size of the gap between the fixed body and the pulley portion is not affected by the width of the actuator portion, this auto tensioner can be used even if the gap is very small.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The autotensioner of the first embodiment shown in FIGS. 1 and 2 comprises an actuator section 11, a pulley section 12 and an arm 13 connecting the two.

In the actuator section 11, as in the conventional case, a bottomed sleeve 15 is fitted and inserted into the inner bottom portion of a cylinder 14 whose lower end is closed, and a piston 16 is slidably inserted into the sleeve 15 and the piston 16 is inserted. The lower part of the is a pressure chamber 17 forming a damper, and the upper part thereof is a reservoir chamber 18. A check valve 21 is provided at the lower end of a valve hole 19 provided at the center of the piston 16.

A push rod 22 is provided at the upper end of the valve hole 19.
And the valve hole 19 and the reservoir chamber 18 communicate with each other through the communication hole 23 provided at the lower end portion of the push rod 22.

Inside the reservoir chamber 18, a push rod 22 is fitted with a guide member 24 slidably contacting the inner peripheral surface of the cylinder 14, and tension adjustment is performed between the guide member 24 and the upper end of the sleeve 15. The spring 25 is interposed. A seal member 26 is attached to the upper end opening of the cylinder 14, and the push rod 22 slidably penetrates the inner peripheral surface of the seal member 26.
Project above. The pressure chamber 17 and the reservoir chamber 1 described above
8 is filled with required hydraulic oil.

A mounting ear 27 is provided on the outer surface of the cylinder 14 (see FIG. 1).

In the pulley section 12, a bearing 29 is integrally formed with a pulley 28 made of synthetic resin, and a tubular support shaft 31 is press-fitted and fixed inside the bearing 29. Belt guides 32 are provided on both sides of the outer peripheral surface of the pulley 28.

Upward U-shaped arms 13 are fixed to the upper ends of the push rods 22 of the actuator section 11, and both ends of the rotary support shaft 31 are fixed to the rising wall portions on both sides of the arm 13. .

In the above-mentioned auto tensioner, the center line L of the push rod 22 is located on the center plane S (the center line in the case shown) of the pulley 28 in the width direction. Further, the cylinder 14 of the actuator portion 11 is narrower than the width of the pulley 28, and is configured to have a width of the belt 33.

The auto tensioner of the first embodiment described above is
Bolt 3 inserted in the mounting ear 27 of the actuator unit 11
4 is attached to the engine block 35. In the illustrated case, the gap g from the engine block 35 to the pulley 28 is not affected by the width of the cylinder 14 of the actuator unit 11, so that the gap g can be set small regardless of the width of the cylinder 14. .

In the above-mentioned auto tensioner, the push rod 22 of the actuator portion 11 rotates about its center line L, so that the posture of the pulley portion 12 may become unstable. However, the guide portions provided on both sides of the pulley 28. Since the belt 32 contacts both side surfaces of the belt 33, the posture of the pulley portion 12 is stable.

In the actuator section 11, the position of the center line L of the push rod 22 is slightly deviated from the center plane S of the pulley 28 in the width direction within a slight margin existing on both sides of the cylinder 14, and It does not matter even if the structure is slightly deviated within the center plane S.

The automatic tensioner of the first embodiment described above pushes the push rod 22 through the pulley portion 12 and the arm 13 when the tension of the belt 33 increases. At this time, the check valve 21 closes the valve hole 19, and the hydraulic oil in the pressure chamber 17 leaks into the reservoir chamber 18 through the minute gap between the piston 16 and the sleeve 15. As a result, a damper action is generated, so that the push rod 22 is gradually pushed in and stops at a point where it balances with the spring force of the tension adjusting spring 25.

On the contrary, when the tension of the belt 33 is relaxed, the push rod 22 is pushed out by the spring force of the tension adjusting spring 25. At this time, the check valve 21 opens the valve hole 19, so that the hydraulic oil in the reservoir chamber 18 moves to the pressure chamber 17 side. Therefore, the push rod 22 rapidly protrudes,
It stops at the point of balance with the above spring force.

The second embodiment shown in FIG. 3 is the arm 1
3 has an L shape, and the pulley portion 12 is attached to the pulley arm 13 by a bolt 36 which is connected to the rotation support shaft 31 of the pulley portion 12. In the case of the first embodiment, the support shaft 3
Whereas both ends of 1 are fixed to the pulley arm 13 in a double-sided type, the second embodiment is a cantilevered type. The other structure is the same as that of the first embodiment. This second
In the case of the embodiment, the gap g between the engine block 35 and the pulley 28 can be further reduced.

[0024]

As described above, according to the present invention, the pulley arm provided at the upper end of the push rod is used so that the center line of the push rod of the actuator portion substantially exists on the center plane in the width direction of the pulley portion. Since the pulley portion is supported, the size of the width of the actuator portion does not affect the size of the gap between the pulley portion and the fixed body such as the engine block. As a result, the gap between the fixed body and the pulley portion can be reduced, so that the autotensioner of the present invention can be used even in a layout in which installation of the conventional autotensioner is structurally unreasonable.

[Brief description of drawings]

FIG. 1 is a front view of the first embodiment.

FIG. 2 is a vertical sectional side view of the above.

FIG. 3 is a vertical sectional side view of the second embodiment.

FIG. 4 is a side view of a conventional example.

[Explanation of symbols]

 11 Actuator part 12 Pulley part 13 Arm 14 Cylinder 15 Sleeve 16 Piston 17 Pressure chamber 18 Reservoir chamber 19 Valve hole 21 Check valve 22 Push rod 23 Insertion hole 24 Guide member 25 Tension adjusting spring 26 Sealing member 27 Mounting ear 28 Pulley 29 Bearing 31 Spindle 32 Belt guide 33 Belt 34 Bolt 35 Engine block 36 Bolt

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[Procedure amendment]

[Submission date] March 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

Auto-tensioner of the first embodiment shown in EXAMPLES 1 and 2, comprising either <br/> et actuator unit 11 and the pulley unit 1 2.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Both ends of the support shaft 31 are fixed to the rising wall portions on both sides of the upward U-shaped arm 13. the above
Arm 13 is connected to the upper end of push rod 22.
However, both may be manufactured as an integral part.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

The second embodiment shown in FIG. 3 is the arm 1
3 shape has an L-shaped, the pulley 28, by bolts 36 and through the rotary shaft 31, attached to the pulley arm 13. In the case of the above-mentioned first embodiment, both ends of the support shaft 31 are fixed to the pulley arm 13, and in the case of the second embodiment, they are cantilever type. The other structure is the same as that of the first embodiment. In the case of the second embodiment, the gap g between the engine block 35 and the pulley 28
Can be further reduced.

Claims (1)

[Claims] 1. A tension adjusting spring is housed inside a cylinder which comprises an actuator portion and a pulley portion and which constitutes the actuator portion, and the pulley portion is inserted through a push rod into which the spring force is inserted into the cylinder. In the automatic tensioner designed to be applied to the above, the support shaft of the pulley is fixed by the arm provided at the tip of the push rod, and the center line of the push rod is substantially positioned on the center plane in the width direction of the pulley. An auto tensioner that is characterized by that.