JP2000329204A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To standardize major components of a cylinder of an auto tensioner to keep a belt tension constant and to improve workability in its assembly process. SOLUTION: A cylinder 1 has a double wall structure with an outer cylinder 1a and an inner cylinder 1b. An oil seal 3 is attached to prevent hydraulic oil filled in the inner cylinder 1b from leaking out. An assembly body A is completed by building a belt pressing rod 6, a tension adjusting spring 8 making the rod 6 stick out and a hydraulic damper mechanism 10 to adsorb load applied to the rod 6 in a compression direction in the inner cylinder 1b. An auto tensioner is formed by inserting this assembly body A into the outer cylinder 1a and putting a coming-off prevention part. Assembly bodies A are therefore, standardized and workability in assembly process is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto tensioner which always keeps the tension of a belt such as a camshaft driving belt of an automobile at an appropriate tension.

[0002]

2. Description of the Related Art An auto-tensioner shown in FIG. 3 is conventionally known as an auto-tensioner for maintaining a constant tension of a camshaft driving belt.

In this automatic tensioner, a seal 31 is attached to the opening of the cylinder 30 to prevent the hydraulic oil filled in the cylinder 30 from leaking. The cylinder 30
Inside, a rod 32, a tension adjusting spring 33 for giving the rod 32 an outward projecting property, and a rod 3
2 and a hydraulic damper mechanism 34 for buffering an axial pushing load applied to the shaft 2.

Here, a hydraulic damper mechanism 34 slidably incorporates a piston 37 forming a pressure chamber 35 and a reservoir chamber 36 inside the cylinder 30, and the piston 37.
A passage 38 communicating between the pressure chamber 35 and the reservoir chamber 36 is formed in the pressure chamber 35, and a check valve 39 for preventing the hydraulic oil in the pressure chamber 35 from flowing into the reservoir chamber 36 is provided in the passage 38.

[0005] The auto tensioner having the above configuration is
A cylinder 30 is mounted on an engine block, and a swingable roller arm (not shown) is pressed by a rod 32 having an outwardly protruding property by a spring force of a tension adjusting spring 33, and a tension roller supported by the roller arm. Is pressed against the belt, and the change in the tension of the belt is absorbed by the tension adjusting spring 33 and the hydraulic damper mechanism 34 so that the belt tension is kept constant.

[0006]

In the above-mentioned auto-tensioner, the outer peripheral shape of the cylinder 30 and the mounting means 40 provided on the outer periphery thereof in accordance with the specification of the mounting surface.
, It is difficult to standardize the cylinder 30.

In the process of assembling the components of the damper mechanism 34 and many components such as the tension adjusting spring 33 and the rod 32 in the cylinder 30, when the cylinder 30 having the mounting means 40 formed integrally is transported or handled. There are still points to be improved, such as workability.

An object of the present invention is to provide an automatic tensioner which can standardize main components of a cylinder and improve workability in an assembling process.

[0009]

In order to solve the above-mentioned problems, according to the present invention, in a cylinder filled with hydraulic oil, a rod, a hydraulic damper mechanism for buffering a pushing load from a belt, and a belt In an auto-tensioner incorporating a tension adjustment spring for applying tension to the cylinder, the cylinder has a double structure of an outer cylinder and an inner cylinder, and a rod, a hydraulic damper mechanism and a tension adjustment spring are incorporated in the inner cylinder. A sealed assembly is completed, and this assembly is incorporated in the outer cylinder.

In the present invention, a rod for pressing a belt, a hydraulic damper mechanism for buffering a pushing load applied from the belt to the rod, and a hydraulic damper mechanism are provided in a cylinder filled with hydraulic oil. In an auto-tensioner incorporating a tension adjusting spring that imparts a protruding property to the inner cylinder, the cylinder has a double structure of an outer cylinder and an inner cylinder, and the outer cylinder is provided with mounting means for a mounting object, and is provided in the inner cylinder. A sealed assembly is completed by incorporating the rod, the hydraulic damper mechanism and the tension adjusting spring, and the assembly is inserted into the outer cylinder to prevent the assembly from coming off.

Here, as a hydraulic damper mechanism, a piston is slidably incorporated into the inner cylinder to form a pressure chamber and a reservoir chamber inside the inner cylinder, and the piston communicates the pressure chamber with the reservoir chamber. And a check valve for preventing the hydraulic oil in the pressure chamber from flowing into the reservoir chamber.

The inner cylinder is sealed at its opening with a seal member such as an oil seal or a diaphragm to prevent leakage of hydraulic oil to the outside and to prevent deterioration of the belt due to adhesion of hydraulic oil. it can.

[0013] As described above, the cylinder is formed by the outer cylinder and the inner cylinder, and the rod, the hydraulic damper mechanism, and the tension adjusting spring are incorporated in the inner cylinder to complete a sealed assembly. Can be standardized. In addition, since the inner cylinder has a simple shape that does not include mounting means and the like, in the process of assembling parts such as the rod, the hydraulic damper mechanism, and the tension adjusting spring in the inner cylinder, the inner cylinder is required to be transported and handled during the process. Workability is improved. Thereafter, if the inner cylinder assembly is incorporated into the outer cylinder, a completed auto tensioner is obtained.

The weight of the auto tensioner can be reduced by using a light metal such as an aluminum alloy for the outer cylinder.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG.
The cylinder 1 has a double structure of an outer cylinder 1a and an inner cylinder 1b, and the outer cylinder 1a is made of a light metal such as an aluminum alloy. Mounting piece 2 is formed.

The inner cylinder 1b is made of a hard metal such as steel, and is filled with a working oil, and an oil seal 3 is press-fitted into an opening. An annular groove 4 is provided on the inner periphery of the opening of the inner cylinder 1b, and a retaining ring 5 attached to the annular groove 4 is provided.
This prevents the oil seal 3 from coming off.

An air space is provided between the oil seal 3 and the surface of the hydraulic oil. A rod 6 for pressing the belt is slidably inserted through the oil seal 3. A slidable wear ring 7 is fitted to the rod 6 along the inner peripheral surface of the inner cylinder 1b, and the wear ring 7 is provided in the middle of the outer periphery of the rod 6 by a tension adjusting spring 8 incorporated in the inner cylinder 1b. The rod 6 is pressed against the stepped portion 6a, and the rod 6 is given an outward projecting property by the tension adjusting spring 8.

Inside the inner cylinder 1b, a rod 6
A hydraulic damper mechanism 10 for buffering an axial pushing load applied to the motor is incorporated.

The hydraulic damper mechanism 10 slidably incorporates a piston 13 partitioning the interior into a pressure chamber 11 and a reservoir chamber 12 inside the inner cylinder 1b, and the piston 13 communicates the pressure chamber 11 and the reservoir chamber 12. A check valve 15 for preventing hydraulic oil in the pressure chamber 11 from flowing into the reservoir chamber 12 through the passage 14 is provided in the passage 14, and the opening and closing amount of the check valve 15 is determined by a piston. 13 is restricted by a retainer 16 attached to the lower projection 13a.

Here, the piston 13 may have a rod insertion hole 13b into which the lower end of the rod 6 is press-fitted on the upper surface thereof, and may be integrally connected to the rod 6. The lower end of the rod 6 may be inserted into the rod insertion hole 13b. A part may be inserted to make it non-coupled. In the case of non-connection, a spring 17 is incorporated in the pressure chamber 11 so that the piston 13 is pressed against the rod 6.

The above is the description of the embodiment in the completed state.

The inner cylinder 1b and the components such as the rod 6, the tension adjusting spring 8, and the hydraulic damper mechanism 10 incorporated therein are prevented from coming off by the oil seal 3 attached to the opening of the inner cylinder 1b. The sealed assembly A is completed.
The assembly A that does not include the mounting means can be standardized. Also, since the inner cylinder 1b has a simple shape that does not include any mounting means or the like, in the process of assembling components such as the operating rod 6, the tension adjusting spring 8, and the hydraulic damper mechanism 10 in the inner cylinder 1b, Workability during transport and handling is improved. This assembly A is inserted into the outer cylinder 1a and is prevented from falling off. Thus, the cylinder 1 is connected to the outer cylinder 1a.
And the inner cylinder 1b has a double structure, so that it can be applied to various mounting surface specifications by changing only the outer cylinder 1a.

In order to prevent the assembly A from coming off, here, the open end of the outer cylinder 1a is swaged, and reference numeral 18 denotes a swaged piece.

The auto tensioner having the above configuration is
Before mounting to the engine of the car, etc., the cylinder 1
The rod 6 is kept pushed by inserting a set pin 19 that penetrates both the rod 6 and the rod 6 in the radial direction. Then, after fixing the mounting piece 2 of the cylinder 1 to the mounting object such as the engine block, the set pin 19 is pulled out, and a swingable swing member (not shown) is provided by the rod 6 which is provided with an outward projecting property by the tension adjusting spring 8. The roller arm is pressed, and the tension roller supported by the roller arm is pressed against the belt to tension the belt.

If the belt becomes slack in the above-described use state of the auto tensioner, the rod 6 moves outward by the pressure of the tension adjusting spring 8 to absorb the slack of the belt, and the belt pushes the rod 6 in. The rod 6 stops at a position where the pushing force and the spring force of the tension adjusting spring 8 are balanced.

When the rod 6 moves outward, the piston 1
3 also moves with the rod 6, and the movement increases the volume of the pressure chamber 11 and decreases the pressure. Therefore, the check valve 15 opens the passage 14, and the hydraulic oil in the reservoir chamber 12 flows into the pressure chamber 11. Inflow.

On the other hand, when the tension of the belt increases and the rod 6 is pressed, the pressure in the pressure chamber 11 increases, so that the check valve 15 closes the passage 14 and the operating oil in the pressure chamber 11 is Leakage enters the reservoir chamber 12 from between the contact portion of the piston 1b and the piston 13, the piston 13 and the rod 6 retreat slowly to absorb a change in the tension of the belt, and the pressing force and the tension adjusting spring 8 for pressing the rod 6 by the belt. When the spring force is balanced, the rod 6 and the piston 13 stop.
Therefore, the belt tension is always kept constant.

FIG. 2 shows another example of the auto-tensioner according to the present invention. In the auto tensioner shown in this example, the rod cover 20 is press-fitted into the open end of the inner cylinder 1b, and the rod 6 is slidably inserted into an insertion hole 21 formed in the rod cover 20.

The opening of the inner cylinder 1b is sealed by a flexible diaphragm 22 provided below the rod cover 20 to prevent leakage of the working oil filled in the inner cylinder 1b.

Further, the passage 14 of the piston 13 is opened and closed by a check valve 15 made of a plate, and the check valve 15 is pressed in the opening direction by a spring 23 having a weak spring force. To give the rod 6 an outward projecting property.

In the above auto tensioner, the inner cylinder 1
b, the tension adjusting spring 8, the hydraulic damper mechanism 10, the diaphragm 22, and the rod 6 are assembled in this order, and the rod cover 20 is pressed into the opening of the inner cylinder 1b to form an assembly A, and the assembly A is mounted. It is inserted into the outer cylinder 1a having the piece 2, and the completed end is formed by caulking the open end of the outer cylinder 1a.

In the auto tensioner shown in FIG.
Since the assembly A is inserted into the outer cylinder 1a, FIG.
, Assembly A can be standardized,
Further, workability in the assembling process can be improved.

Therefore, by changing only the outer cylinder 1a, it is possible to obtain an auto-tensioner applicable to various specifications of the mounting surface.

[0034]

As described above, according to the present invention, the assembly inserted into the outer cylinder can be standardized. In addition, it is possible to improve the workability in the assembling process, and it is possible to obtain an auto-tensioner suitable for various mounting surface specifications by changing the outer cylinder.

Further, the weight of the auto tensioner can be reduced by forming the outer cylinder from a light metal such as an aluminum alloy.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional front view showing another example of the auto tensioner according to the present invention.

FIG. 3 is a longitudinal sectional front view showing a conventional auto tensioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 1a Outer cylinder 1b Inner cylinder 3 Oil seal A Assembly 6 Rod 8 Tension adjusting spring 10 Hydraulic damper mechanism 11 Pressure chamber 12 Reservoir chamber 13 Piston 14 Passage 15 Check valve 22 Diaphragm

Claims (8)

[Claims] An auto tensioner incorporating a rod, a hydraulic damper mechanism for buffering a pushing load from a belt, and a tension adjusting spring for applying tension to a belt in a cylinder filled with hydraulic oil, The cylinder has a double structure of an outer cylinder and an inner cylinder, and a rod, a hydraulic damper mechanism and a tension adjusting spring are incorporated in the inner cylinder to complete a sealed assembly, and this assembly is placed in the outer cylinder. Auto tensioner characterized by being incorporated. 2. A belt for pressing a belt, a hydraulic damper mechanism for buffering a pushing load applied to the rod from the belt, and a projecting property of the rod in an outward direction in a cylinder filled with hydraulic oil. In an auto tensioner incorporating a tension adjusting spring to be applied, the cylinder has a double structure of an outer cylinder and an inner cylinder, and mounting means for an object to be mounted is provided on the outer cylinder, and the rod, a hydraulic damper are provided in the inner cylinder. An auto tensioner wherein a sealed assembly is completed by incorporating a mechanism and a tension adjusting spring, and the assembly is inserted into the outer cylinder to prevent the assembly from falling off. 3. The hydraulic damper mechanism has a piston slidably incorporated in the inner cylinder to form a pressure chamber and a reservoir chamber inside the inner cylinder, and the piston communicates the pressure chamber with the reservoir chamber. 3. The auto-tensioner according to claim 1, wherein a passage is provided, and a check valve is provided in the passage to prevent hydraulic oil in the pressure chamber from flowing into the reservoir chamber. 4. The auto-tensioner according to claim 1, wherein an opening of the inner cylinder is sealed with a seal member through which the rod is inserted. 5. The auto-tensioner according to claim 4, wherein the seal member comprises an oil seal, and the rod is slidably penetrated through the oil seal. 6. The auto tensioner according to claim 4, wherein said seal member is made of a flexible diaphragm. 7. The auto-tensioner according to claim 5, wherein an air layer is provided between the oil seal and the hydraulic oil. 8. The auto tensioner according to claim 1, wherein the outer cylinder is made of light metal.