JP3347194B2 - Auto tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tensioner for adjusting the tension of a timing belt or a timing chain of an engine or a belt for driving auxiliary equipment.

[0002]

2. Description of the Related Art As an automatic tensioner for adjusting the tension of a belt or the like of this type, there is a conventional one having a structure as shown in FIGS.

This device has a rolling member 33 rotatably supporting a pulley 32 on a fixed member 31 such as an engine block, and a hole 34 eccentric to the rolling bearing 33, and is integrally formed with an inner ring of the rolling bearing 33. Swing shaft 35 to be fixed
And a cylinder 37 having a built-in hydraulic shock absorbing mechanism for accommodating the operating rod 36 so as to be movable forward and backward.
The operating rod 36 of the hydraulic shock absorbing mechanism protruding from the shaft abuts on a stopper 38 protruding from the end of the swing shaft 35.

In the above structure, when the pulley 32 swings in the direction in which the belt tension is loosened, the operating rod 36 rapidly protrudes to fill a gap with the stopper 38, and conversely, the belt tension increases, and the swing shaft 35 From the stopper 38 to the operating rod 36
When the force is applied in the pushing direction, the operating rod 36 is gently pushed by the buffer effect of the hydraulic buffer mechanism, and the belt tension is kept constant.

[0005]

However, in the above-mentioned conventional apparatus, an operating rod 36 of a cylinder 37 having a built-in hydraulic shock absorbing mechanism is brought into contact with a stopper 38 protruding from an end of a swing shaft 35. A gap G is required between the pulley 32 and the surface of the fixing member 31 to allow the cylinder 37 to enter, and the height of the adjusting device is accordingly increased.

[0006] For this reason, there is a problem that it is difficult to mount the above-mentioned conventional device in an engine in which the dimensions are not very large between the belt and the engine block.

Therefore, the present invention solves the above-mentioned problem,
It is an object of the present invention to provide an auto tensioner capable of integrally forming a pulley supporting portion and a hydraulic shock absorbing mechanism with a compact height.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an arm which is swingable about a fulcrum shaft provided on a fixed member, and a swing-side end of the arm. provided pulley a rotatably supported to impart tension to the belt by a pulley support shaft, the arm, the hydraulic cushioning mechanism and a return spring is incorporated cylinder on one side of the pulley, the axis thereof Within the width of the pulley
The distal end of the operating rod of the hydraulic shock absorbing mechanism, which is provided in parallel with the pulley so as to be positioned so as to be able to protrude and retract from the cylinder, is brought into contact with a stopper provided on the fixing member, and the arm is pressed by the belt. The operating rod was pushed in when the rocking motion occurred.

[0009]

In the above structure, the pulley and the cylinder containing the hydraulic buffering mechanism swing together, and the stopper pushes the operating rod to exhibit a buffering function. In this structure, the cylinder is provided on the side of the pulley, the cylinder
Are arranged in parallel with the pulley so that the axis of the pulley is located within the width of the pulley, the height of the auto tensioner can be reduced.

[0010]

1 to 3 show a first embodiment of the present invention. A base plate 2 is mounted on the surface of the engine block 1, and an arm 3 is mounted on the surface of the base plate 2.

A fulcrum bolt 4 that is fixed to the engine block 1 through the base plate 2 is attached to one end of the arm 3, and the fulcrum bolt 4 and a bearing 5 fitted outside thereof support the arm 3. It swings around the bolt 4 as a fulcrum.

A mounting bolt 7 is mounted on an elongated hole 6 formed at the end of the base plate 2, and the base plate 2 is fixed to the engine block 1 by the mounting bolt 7 and the fulcrum bolt 4.

[0013] The swinging side end of the arm 3 pulley support shaft 8 is provided integrally, the pulley 10 is rotatably supported via the bearings 9 to the pulley support shaft 8.

The arm 3 has a cylindrical cylinder 1 having a hydraulic buffer mechanism 12 built in one side of the pulley 10.
1 are provided integrally so that the axis thereof is located within the width of the pulley . The hydraulic shock absorbing mechanism 12 has a plunger 14 slidably inserted into a sleeve 13 provided in the cylinder 11, and the plunger 14 allows the cylinder 1 to be moved.
1, a hydraulic oil chamber 15 is divided into a pressure chamber 16 and a reservoir chamber 17, and a passage 18 communicating the pressure chamber 16 and the reservoir chamber 17 is provided in the plunger 14, and the hydraulic oil on the pressure chamber 16 side is provided in the passage 18. A check valve 19 is provided for closing the passage 18 when the pressure increases from the reservoir chamber 17 side.

An operating rod 20 is connected to the plunger 14, and a return spring 22 is incorporated between the wear ring 21 engaged with the step of the operating rod 20 and the upper end of the sleeve 13. And the plunger 14 and the operating rod 20 are provided with a spring force in a direction protruding outward from the cylinder 11.

A spring 24 for connecting the retainer 23, the plunger 14 and the operating rod 20 is incorporated in the pressure chamber 16, and an oil seal 25 is provided at the opening of the cylinder 11.

Further, a stopper 26 is provided upright on a side edge of the base plate 2 facing the cylinder 11, and the operating rod 20 of the hydraulic shock absorbing mechanism 12 is brought into contact with the stopper 26.

The auto-tensioner of the embodiment has the above-described structure. When the tension of the belt A increases and the pulley 10 and the arm 3 swing clockwise about the fulcrum bolt 4 in FIG. Since the and the cylinder 11 rotate as a unit, the operating rod 20 is pressed toward the stopper 26 and tends to be pushed into the cylinder 11 by the pressure. In this case, when the plunger 14 is about to be pushed into the pressure chamber 16, the pressure in the pressure chamber 16 increases, and the check valve 19 closes the passage 18.
Hydraulic fluid leaks into the reservoir chamber 17 from between the sliding surfaces of the plunger 14 and the sleeve 13 to buffer the movement of the plunger 14 and the operating rod 20. Therefore, the arm 3 and the pulley 10 swing slowly, responding to an increase in belt tension.

Conversely, the tension of the belt A decreases, and the pulley 1
0 and the arm 3 swing counterclockwise in FIG.
1 swings away from the stopper 26, and the operating rod 20 attempts to protrude outward by the spring force of the return spring 22. In this case, the pressure in the pressure chamber 16 decreases due to the rise of the plunger 14, and the check valve 19 opens the passage 18, so that the operating oil in the reservoir chamber 17 moves to the pressure chamber 16 through the passage 18 and the operating rod 20. Protrudes rapidly to fill the gap between the stopper 26.
At this time, the arm 3 and the pulley 10 stop at a position where the pressing force acting between the operating rod 20 and the stopper 26 and the spring force of the return spring 22 are balanced.

In the above structure, the pulley 10 is attached to the arm 3.
And a cylinder 1 having a built-in hydraulic shock absorbing mechanism 12 on one side thereof
1 is provided, the pulley 10 and the cylinder 11, the cylinder
Since the shafts of the rollers 11 are arranged in parallel so as to be positioned within the width of the pulley 10, the mounting height of the entire auto tensioner can be reduced. Therefore, engine block 1
Even if there is no dimensional margin between the belt and the belt A, the apparatus can be mounted without any trouble.

A stopper 2 is provided on the base plate 2.
Since the 6 is provided, even in a place where it is difficult to install the stopper at the end of the engine block 1 or the like, if the engine block is machined with a bolt hole for mounting the base plate 2, the auto tensioner can be easily attached.

FIGS. 4 to 6 show a second embodiment. In this example, a base plate is not provided between the arm 3 and the engine block 1, and the fulcrum bolt 4
Is directly attached to the engine block 1.

Further, a stopper pin 27 is provided on the engine block 1, and the stopper pin 27 is
Operating rods 20 are in contact with each other.

Since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 7 shows a third embodiment. The structure of this example and the structure of the first embodiment are the same in that the base plate 2 is interposed between the arm 3 and the engine block 1 and that the stopper 26 is provided on the base plate 2. There is a difference in the structure of the hydraulic shock absorbing mechanism 12 built in 11.

That is, in the hydraulic shock absorbing mechanism 12 of this embodiment, an annular gap 2 is provided between the cylinder 11 and the sleeve 13.
The return spring 22 is fitted in the gap 28, thereby shortening the overall length of the cylinder 11 and the hydraulic shock absorbing mechanism 12, and reducing the weight of the entire swinging arm 3. When the inertial weight of the arm 3 is reduced in this manner, the ability to follow the buffering force of the hydraulic buffering mechanism 12 is greatly improved, and even if high frequency vibration is applied from the belt A to the cylinder 11 integrated with the pulley 10, a stable operation is achieved. The function of tension adjustment can be maintained.

[0027]

As described above, according to the present invention, the pulley and the cylinder having the built-in hydraulic shock absorbing mechanism and the return spring are provided on the swingably supported arm, and the pulley and the cylinder are mounted on the cylinder 11. Axis of pulley 10
The height of the auto-tensioner can be reduced in size because it is arranged in parallel so as to be located within the width of, and the auto-tensioner can be mounted in a place where there is not enough space for mounting.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal front view showing a first embodiment.

FIG. 2 is a longitudinal side view taken along the line II-II in FIG.

FIG. 3 is a side view taken along the line III-III in FIG. 1;

FIG. 4 is a partially longitudinal front view showing a second embodiment.

FIG. 5 is a longitudinal sectional side view taken along line VV in FIG. 4;

FIG. 6 is a side view as viewed from the line VI-VI in FIG. 4;

FIG. 7 is a partially longitudinal front view showing a third embodiment.

FIG. 8 is a side view showing a conventional example.

FIG. 9 is a bottom view taken along line IX-IX in FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 engine block 2 base plate 3 arm 4 fulcrum bolt 8 pulley support shaft 10 pulley 11 cylinder 12 hydraulic buffer mechanism 13 sleeve 14 plunger 15 operating oil pressure 16 pressure chamber 17 reservoir chamber 18 passage 19 check valve 20 operating rod 22 return spring 26 stopper 27 stopper pin

Claims (2)

(57) [Claims] An arm is swingably provided around a fulcrum shaft provided on a fixed member, and a pulley for applying tension to a belt is rotated by a pulley support shaft provided at a swing-side end of the arm. The arm has a cylinder in which a hydraulic shock absorbing mechanism and a return spring are built in one side of the pulley , and the axis of the cylinder is located within the width of the pulley.
The end of the operating rod of the hydraulic shock absorbing mechanism, which can be freely retracted from the cylinder, is brought into contact with a stopper provided on the fixing member, and the arm is pressed by the belt. Auto tensioner that pushes the operating rod when swings. 2. The auto-tensioner according to claim 1, wherein a fixing member to which the arm is attached is detachable from another fixing member.