JPH0874954A - Auto tensioner - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the radial and axial dimensions of the autotensioner, and to reduce the size and sealing area of the seal member that seals the reservoir chamber and the air chamber to ensure reliable sealing. [Structure] A body 1 in which a cylinder 11 is formed, a reservoir chamber 26 formed by a piston 21 and a through hole 25 which are arranged so as to face the body 1 and are inserted in the cylinder 11 and an upper portion thereof. A chamber in which the rod member 2 having an air chamber 27 formed therein, a spring 3 inserted between the body 1 and the rod member 2, and the spring 3 formed outside the cylinder 11 are inserted. 4, an autotensioner including a pressure oil chamber 5 formed in the cylinder 11, and a boot 6 interposed between the body 1 and the rod member 2 so as to cover the spring 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tensioner that maintains the tension of a belt at a set tension.

[0002]

2. Description of the Related Art A conventional first automatic tensioner is shown in FIG.
As shown in FIG. 5, a reservoir chamber RC is formed in a recess in a body B in which a cylinder C in which a piston P of a rod member R is inserted is arranged, and the body B and the rod member R are formed in the reservoir chamber RC. A spring S is interposed between the body B and the rod member R, and rubber boots G for sealing are attached to the outer walls of the body B and the rod member R. As a result, an air chamber A is formed above the reservoir chamber RC.

Also, in the second conventional automatic tensioner (actual fair 3-13647), a piston P of a rod member R is inserted in a cylinder C formed in a body B as shown in FIG. The spring S is inserted in the reservoir chamber RC between the shoulder portion of the reservoir member R and the shoulder portion of the rod member R, and the air chamber A is formed in the upper portion of the reservoir chamber RC.

[0004]

Since the first conventional autotensioner described above has the reservoir chamber RC and the air chamber A formed outside the cylinder C of the body B as shown in FIG. Since the rubber boots G for sealing are mounted on the outer walls of the body B and the rod member R as the size in the radial direction and the axial direction increases, there is a problem that the size of the rubber boot G and the sealing area increase. It was

In the second conventional automatic tensioner, the reservoir chamber RC and the air chamber A are formed between the cylinder C of the body B and the rod member R as shown in FIG. In addition, the size in the axial direction becomes large, and there is a problem in that it is necessary to dispose a large annular oil seal OS that seals the gap between the upper end of the cylinder C and the rod member R.

Therefore, the present inventors have paid attention to the technical idea of the present invention of forming a reservoir chamber and an air chamber in the rod member, and have conducted further research and development to determine the dimensions of the automatic tensioner in the radial direction and the axial direction. As well as
The present invention has been achieved which achieves the purpose of ensuring the seal by reducing the size and sealing area of the sealing member that seals the reservoir chamber and the air chamber.

[0007]

The autotensioner of the present invention (the first invention according to claim 1) is a body in which a cylinder is formed, and is disposed so as to face the body, and is interposed in the cylinder. An auto tensioner including a rod member having a piston to be inserted and a spring interposed between the body and the rod member forms a pressure oil chamber in the cylinder in which the piston is inserted. In addition, a reservoir chamber and an air chamber are formed in the rod member.

In the autotensioner of the present invention (the second invention according to claim 2), in the first invention, a through hole is formed in the rod member, and the reservoir communicating with the pressure oil chamber is provided in the through hole. A chamber is formed.

In the autotensioner of the present invention (the third invention according to claim 3), in the second invention, the air chamber is formed above the reservoir chamber in the through hole formed in the rod member. It is what

The autotensioner of the present invention (the fourth invention according to claim 4) is the autotensioner according to the third invention, wherein a check ball is arranged below a through hole formed in the rod member.

In the autotensioner of the present invention (the fifth invention according to claim 5), in the fourth invention, a seal member is provided between the upper end of the cylinder of the body and the rod member, and A communication hole is formed in the rod member to communicate the chamber formed between the piston and the seal member with the reservoir.

[0012]

In the autotensioner of the first aspect of the present invention having the above structure, when the tension acting on the belt is large and the opposing distance between the body and the rod member becomes small against the biasing force of the spring, the piston is Oil is supplied from the pressure oil chamber formed in the inserted cylinder to the reservoir chamber formed in the rod member through the gap between the cylinder and the piston, and conversely to the belt. When the tension acting is small and the facing distance between the body and the rod member is large due to the urging force of the spring, the pressure in the reservoir chamber increases and oil is supplied from the reservoir chamber to the pressure oil chamber. .

In the autotensioner of the second invention having the above-mentioned structure, when the tension acting on the belt is large and the opposing distance between the body and the rod member becomes small against the urging force of the spring, the piston is Oil from the pressure oil chamber formed in the inserted cylinder to the reservoir chamber constituted by the through hole formed in the rod member through the gap between the cylinder and the piston On the contrary, when the tension applied to the belt is small and the urging force of the spring increases the facing distance between the body and the rod member, the pressure in the reservoir chamber formed in the rod member increases. Oil is supplied from the reservoir chamber to the pressure oil chamber.

In the autotensioner of the third aspect of the present invention having the above structure, when the tension acting on the belt is large and the opposing distance between the body and the rod member becomes small against the urging force of the spring, the piston is moved. Oil is formed together with the air chamber from the pressure oil chamber formed in the inserted cylinder through the through hole formed in the rod member through the gap between the cylinder and the piston. When the tension supplied to the reservoir chamber and acting on the belt on the contrary is small and the facing distance between the body and the rod member increases due to the biasing force of the spring, the reservoir chamber formed in the rod member The pressure increases and oil is supplied from the reservoir chamber to the pressure oil chamber.

In the automatic tensioner of the fourth aspect of the present invention having the above structure, when the tension acting on the belt is large and the opposing distance between the body and the rod member becomes small against the urging force of the spring, the piston moves. Oil is formed together with the air chamber from the pressure oil chamber formed in the inserted cylinder through the through hole formed in the rod member through the gap between the cylinder and the piston. When the tension supplied to the reservoir chamber and, conversely, acting on the belt is small and the opposing distance between the body and the rod member increases due to the urging force of the spring, the reservoir chamber formed in the rod member The pressure increases, and the pressure oil chamber is transferred from the reservoir chamber to the pressure oil chamber through the check ball disposed below the through hole formed in the rod member. Yl is supplied.

In the automatic tensioner of the fifth aspect of the present invention having the above structure, when the tension acting on the belt is large and the opposing distance between the body and the rod member becomes small against the biasing force of the spring, the piston is Oil from the pressure oil chamber formed in the inserted cylinder passes through a gap between the cylinder and the piston, and is arranged between the upper end of the cylinder and the rod member. Through the chamber formed between the seal member and the piston and the communication hole formed in the rod member, supplied to the reservoir chamber formed together with the air chamber,
Conversely, when the tension acting on the belt is small and the opposing distance between the body and the rod member increases due to the urging force of the spring, the pressure in the reservoir chamber formed in the rod member increases, and Oil is supplied from the chamber to the pressure oil chamber via the check ball provided below the through hole formed in the rod member.

[0017]

In the autotensioner of the first aspect of the invention having the above-described operation, the reservoir chamber and the air chamber are formed in the rod member, so that the reservoir chamber and the air chamber are formed outside the cylinder as in the conventional case. Therefore, it is possible to reduce the size in the radial direction and the axial direction and to reduce the sealing area for sealing the reservoir chamber and the air chamber.

In the autotensioner according to the second aspect of the present invention having the above-mentioned operation, the reservoir chamber is constituted by the through hole formed in the rod member, so that the reservoir chamber and the air chamber are provided outside the cylinder as in the conventional case. Since it is not necessary to form the structure, it is possible to reduce the size in the radial direction and the axial direction and to reduce the sealing area for sealing the reservoir chamber, and to form the reservoir chamber with a simple through hole. In addition to being able to do so, there is an effect that communication with the pressure oil chamber is easy.

In the autotensioner according to the third aspect of the present invention, which has the above-described operation, since the reservoir chamber and the air chamber are formed by the through hole formed in the rod member, the reservoir is provided outside the cylinder as in the conventional case. Since it is not necessary to form the chamber and the air chamber, it is possible to reduce the size in the radial direction and the axial direction, and to reduce the sealing area that seals the reservoir chamber and the air chamber. This has the effect of forming the air chamber and eliminating the need for special communication means.

In addition to the effect of the third aspect of the invention, the autotensioner of the fourth aspect of the invention has a small tension acting on the belt, and the biasing force of the spring increases the facing distance between the body and the rod member. At this time, the pressure of the reservoir chamber formed in the rod member becomes large, and the pressure oil is passed from the reservoir chamber to the check ball arranged below the through hole formed in the rod member. Since the oil is quickly supplied to the chamber, it is possible to quickly apply tension to the belt.

In addition to the effect of the fourth aspect of the invention, the autotensioner of the fifth aspect of the invention having the above-mentioned action has the seal member arranged between the upper end of the cylinder and the rod member, so that the conventional autotensioner has the above-mentioned effect. As compared with the case where the reservoir chamber and the air chamber are formed outside the cylinder, the sealing member and the sealing area for sealing the reservoir chamber and the air chamber are made smaller, so that the sealing is surely achieved.

[0022]

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

(First Embodiment) The automatic tensioner of the first embodiment controls the tension of the timing V belt of the engine at a constant level. As shown in FIGS. 1 to 3, a body 1 having a cylinder 11 is formed. And a piston 21 which is disposed so as to face the body 1 and is inserted into the cylinder 11.
Rod member 2 having a reservoir chamber 26 formed by a through hole 25 and an air chamber 27 formed above the reservoir chamber 26.
A spring 3 inserted between the body 1 and the rod member 2, a chamber 4 formed outside the cylinder 11 in which the spring 3 is inserted, and a pressure formed in the cylinder 11. It is composed of an oil chamber 5 and a boot 6 inserted between the body 1 and the rod member 2 so as to cover the spring 3.

As shown in FIG. 1, the body 1 has a mount base circular hole 12 formed in a lower base portion 10, and a hollow cylindrical cylinder 11 is coaxially formed above the base portion 10. ing. The pressure oil chamber 5 is formed by the inner peripheral wall of the cylinder 11 and the piston 21.

As shown in FIG. 1, the rod member 2 has a circular hole 22 for mounting formed in an upper base portion 20, and a piston rod in which the piston 21 and the rod are coaxially integrally formed downward. A protruding portion 24 to which the portion 23 is fixed is formed.

As shown in FIG. 1, the piston rod portion 23 is composed of a hollow body having a through hole 25 formed in the center thereof, and a check ball 28 is inserted into a large-diameter lower end portion of the piston 21. When the piston 21 descends, it is closed, and when the piston 21 rises, it is opened so that the reservoir chamber 26 and the pressure oil chamber 5 can communicate with each other.

An oil seal 14 and a snap ring 15 are disposed between the upper end of the cylinder 11 and the rod portion 232 of the piston rod portion 23, and when the piston 21 descends, the cylinder 11 and the piston 21 gradually increases the gap between the oil seal 14 and
The oil filled in the chamber 233 between the piston 21 and the piston 21 is sealed, and the through hole 2 is formed through the communication hole 231 formed in the rod portion 232 of the piston rod portion 23.
5 is configured so as to be able to supply to the reservoir chamber 26 formed in the lower part.

The chamber formed in the protruding portion 24 of the rod member 2 communicates with the through hole 25 formed in the piston rod portion 23, and the reservoir chamber 2
It constitutes a part of the air chamber 27, which is a pressure chamber whose pressure changes in accordance with the amount of oil supplied to the valve 6.

As shown in FIG. 1, the spring 3 is inserted between an annular flat surface on the upper surface of the base portion 10 of the body 1 and an annular flat surface on the lower surface of the base portion 20 of the rod member 2. The coil spring 30 is included.

As shown in FIGS. 1 and 2, the boot 6 is constituted by a rubber bellows-shaped cylindrical body having a breathing hole 61 formed at a lower end thereof, and an upper portion of an outer wall of the base portion 10 of the body 1. The upper end and the lower end of the rod member 2 are fitted and mounted in an annular hole formed in the lower portion of the outer wall of the base portion 20 of the rod member 2.

As shown in FIG. 3, the auto tensioner engages with the circular hole 22 of the rod member 2 at the upper end, and has one end 71 engaged with the circular hole 12 of the base portion 10 of the body 1 at the lower end. The tension roller 73 is rotatably supported by the other end 72 of the substantially J-shaped arm member 7 which is rotatably supported in the central portion, and when the V-belt is loosened, the base portion 10 is lowered. When the tension of the V-belt increases, the tension roller 73 swings counterclockwise to impart tension to the V-belt.
By swinging in the clockwise direction and moving the base portion 10 upward, the tension acting on the V-belt can be reduced.

In the automatic tensioner of the first embodiment having the above-mentioned structure, when the tension acting on the belt V is lowered and the belt V is loosened, the base portion 1 of the body 1 is
No. 0 annular flat surface and the base portion 2 of the rod member 2
The base portion 1 facing each other by the urging force of the coil spring 30 inserted between the lower surface of 0 and the annular flat surface.
Since the facing distance between 0 and 20 increases, that is, the piston 21 moves upward, the volume of the pressure oil chamber 5 increases, and the pressure decreases as compared with the pressures of the reservoir chamber 26 and the air chamber 27. Since the check ball 28 is opened and oil is supplied from the reservoir chamber 26 into the pressure oil chamber 5, the base portion 10 of the body 1 is moved downward, so that the arm member 7 is used to move the base portion 10 downward. The tension roller 73 swings counterclockwise and the belt V
To give tension to the.

On the contrary, when the tension acting on the belt V increases, the idler pulley 73 swings clockwise,
By moving the base portion 10 upward against the biasing force of the coil spring 30, that is, the facing distance between the facing base portions 10 and 20 decreases,
That is, since the piston 21 moves downward and the volume of the pressure oil chamber 5 decreases and the pressure rises, the check ball 28 closes and the communication relationship between the reservoir chamber 26 and the pressure oil chamber 5 is broken. Therefore, the oil in the pressure oil chamber 5 is supplied to the chamber through the gap between the cylinder 11 and the piston 21, is supplied to the reservoir chamber 26 through the communication hole 231, and acts on the belt V. It is to reduce the tension.

Further, the auto tensioner of the first embodiment is
The reservoir chamber 26 and the air are coaxially arranged inside the rod member 2 forming the chamber 4 in which the coil spring 30 forming the spring inserted between the body 1 and the rod member 2 is inserted. A chamber 27 is formed, and the supply of oil is controlled according to the fluctuation of the pressure of the pressure oil chamber 5 and the movement of the piston 21.

In the autotensioner of the first embodiment having the above-mentioned operation, since the reservoir chamber 26 and the air chamber 27 are constituted by the through hole 25 formed in the rod member 2, a spring is not used as in the conventional case. Since it is not necessary to form the reservoir chamber and the air chamber outside the rod member 2 and the cylinder 11 to be inserted, the radial and axial dimensions of the autotensioner can be reduced, and the reservoir chamber 26 and the air chamber can be reduced. This has the effect of reducing the size and the sealing area of the oil seal 14 that seals the seal 27 and making the sealing easy and reliable.

Further, in the auto tensioner of the first embodiment, the tension acting on the belt V is small, and the body 1 and the rod member 2 are urged by the urging force of the coil spring 30.
When the facing distance to the rod member 2 is increased, the pressure of the reservoir chamber 26 formed in the rod member 2 is increased, and the pressure increases from the reservoir chamber 26 to the lower portion of the through hole 25 formed in the rod member 2. The check ball 2 arranged
Since the oil is rapidly supplied to the pressure oil chamber 5 via 8, it is possible to quickly apply the required tension to the belt V.

Furthermore, the auto tensioner of the first embodiment is
Since the oil seal 14 is disposed between the upper end of the cylinder 11 and the rod member 2, the reservoir chamber 26 is different from the case where the reservoir chamber and the air chamber are formed outside the cylinder 11 as in the conventional case. And the air chamber 2
The size and the sealing area of the oil seal that seals 7 are reduced, and the effect of ensuring the sealing is obtained.

Further, in the autotensioner of the first embodiment, since the reservoir chamber is formed by the through hole formed in the rod member, the reservoir chamber can be formed by a simple through hole. The effect that it is easy to communicate with the pressure oil chamber is achieved.

Furthermore, the auto tensioner of the first embodiment is
Since the reservoir chamber and the air chamber are formed by the through hole formed in the rod member, the air chamber is formed in the upper part of the reservoir chamber, and there is an effect that a special communication unit is unnecessary. .

The autotensioner of the first embodiment protects the coil spring 30 by the boot 6 and, even if water is generated in the boot 6 due to changes in temperature and humidity, the breather hole 61 prevents Since the water can be drained, the life of the entire boot 61 and the automatic tensioner can be extended semipermanently.

Further, the auto tensioner of the first embodiment is
As shown in FIGS. 1 and 2, the boot 6 constituted by a rubber bellows-shaped cylindrical body having a breathing hole 61 formed at a lower end thereof is provided on the upper portion of the outer wall of the base portion 10 of the body 1 and the boot portion. Since the upper end and the lower end are fitted and mounted in the annular hole formed in the lower portion of the outer wall of the base portion 20 of the rod member 2, when the tension of the belt V changes, the piston 21 in the cylinder 11 correspondingly changes. It has the effect of enabling smooth sliding.

In the auto tensioner of the first embodiment, the coil spring 30 constituting the spring 3 is interposed between the upper surface of the base portion 10 of the body 1 and the lower surface of the base portion 20 of the rod member 2. Since it is inserted and can be designed in the maximum space of the automatic tensioner, it is possible to obtain a tensioner with high thrust.

The embodiments described above are merely examples for the purpose of explanation, and the present invention is not limited to them. Those skilled in the art will recognize from the claims, the detailed description of the invention and the description of the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

In the above embodiment, the boot 6 protects the coil spring 30, and
Even if water is generated in the boot 6 due to changes in temperature and humidity, an example of draining the water through the breathing hole 61 has been described, but the present invention is not limited thereto, and as shown in FIG. It is also possible to employ a mode in which the hard covers 81 and 82 of hollow cylindrical bodies having different diameters are arranged to face the base portions 11 and 21 of the body 1 and the rod member 2, respectively.

[Brief description of drawings]

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

FIG. 2 is a side view showing the auto tensioner of the first embodiment.

FIG. 3 is a side view showing a mounting mode of the auto tensioner of the first embodiment.

FIG. 4 is a vertical sectional view showing an automatic tensioner of a modified example of the invention.

FIG. 5 is a vertical cross-sectional view showing a first conventional automatic tensioner.

FIG. 6 is a vertical cross-sectional view showing a second conventional automatic tensioner.

[Explanation of symbols]

 1 Body 2 Rod Member 3 Spring 4 Room 5 Pressure Oil Chamber 6 Boot 11 Cylinder 21 Piston 25 Through Hole 26 Reservoir Chamber 27 Air Chamber

Claims (5)

[Claims] 1. A body in which a cylinder is formed, a rod member provided facing the body and provided with a piston inserted in the cylinder, and an intermediate member between the body and the rod member. An autotensioner including an inserted spring, wherein a pressure oil chamber is formed in the cylinder in which the piston is inserted, and a reservoir chamber and an air chamber are formed in the rod member. Auto tensioner. 2. The autotensioner according to claim 1, wherein a through hole is formed in the rod member, and the reservoir chamber communicating with the pressure oil chamber is formed in the through hole. 3. The auto tensioner according to claim 2, wherein the air chamber is formed above the reservoir chamber in a through hole formed in the rod member. 4. The automatic tensioner according to claim 3, wherein a check ball is arranged below a through hole formed in the rod member. 5. The piston and the seal member according to claim 4, wherein a seal member is provided between an upper end of the cylinder of the body and the rod member, and a communication hole is formed in the rod member. An autotensioner characterized in that a chamber formed between the reservoir and the reservoir communicates with the reservoir.