JP2002364720A - Chain tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a chain tensioner by exhausting air stagnant in a pressure chamber to the outside. SOLUTION: A plunger 3 and a spring 17 for pressing the plunger 3 outward are set in a cylinder chamber 2 formed in a housing 1. The housing 1 has a hole 22 in communication with the pressure chamber 4 formed at the back of the plunger 3 from an outer circumferential upper portion. The hole 22 is press-fitted with a plug 23 of an air-permeable material such as sintered metal, so that under a pressure increase in the pressure chamber 4, air stagnant in the pressure chamber 4 is exhausted to the outside from inside the plug 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain tensioner for maintaining a constant tension of a chain such as a camshaft driving chain.

[0002]

2. Description of the Related Art A chain tensioner shown in FIG. 4 is conventionally known as a chain tensioner for maintaining a constant tension of a camshaft driving chain. This chain tensioner incorporates a plunger 53 and a spring 54 that presses the plunger 53 outward in a cylinder chamber 52 formed in a housing 51.
Refueling passage 5 communicating with pressure chamber 55 provided at the back of 3
A check valve 57 is provided on the oil outlet side of the oil supply passage 56 to supply hydraulic oil discharged from the oil pump from the oil supply passage 56 into the pressure chamber 55.
The hydraulic oil encapsulated in the buffering buffer 5 cushions the pushing force applied from the chain to the plunger 53, and when the pushing force is stronger than the elasticity of the spring 54, the pressure chamber is shifted from the sliding surface between the cylinder chamber 52 and the plunger 53. The hydraulic oil in the nozzle 55 is leaked to the outside, and the plunger 53 is slowly moved backward to a position where the pushing force and the elasticity of the spring 54 are balanced.

When the chain becomes slack, the plunger 53 is rapidly moved outward by the elasticity of the spring 54 to absorb the slack of the chain.

By the way, in the above-mentioned chain tensioner, when the engine is started, the pressure chamber 55 is moved from the oil pump.
In some cases, air is entrained in the hydraulic oil supplied to the inside, and the hydraulic oil mixed with the air is supplied into the pressure chamber 55.

Further, when the plunger 53 moves rapidly outward, the pressure in the pressure chamber 55 drops sharply.
Air dissolved in the hydraulic oil may precipitate, or external air may enter the pressure chamber from between the sliding surface of the plunger 53 and the cylinder chamber 52.

Here, if the air that has entered the pressure chamber 55 accumulates in the pressure chamber 55, when the chain is tensioned and the plunger 53 is pushed in, the plunger 53 compresses the air. The damper effect is reduced, and the function as a chain tensioner cannot be sufficiently exhibited.

In order to solve such inconvenience, the chain tensioner is provided with an exhaust means for exhausting the air in the pressure chamber 55 to the outside.

As shown in FIG. 4, a screw hole 58 communicating with the pressure chamber 55 is formed from the upper part of the outer periphery of the housing 51 as an exhaust means, and a screw 59 is screwed into the screw hole 58, and the screw engagement is performed. A structure in which air accumulated in the pressure chamber 55 is discharged to the outside through a spiral screw clearance formed between the surfaces, or as shown in FIG.
3, a hole 60 communicating with the inside of the pressure chamber 55 from the tip end surface is formed. Conventionally, a device that discharges the air to the air is known.

[0009]

The exhaust means shown in FIGS. 4 and 5 is disadvantageous in terms of cost because it requires screw machining and spiral groove machining, and reduces the cost of the chain tensioner. There are still points to be improved.

An object of the present invention is to reduce the cost of a chain tensioner by allowing air in a pressure chamber to be exhausted by an exhaust means having a simple structure.

[0011]

According to a first aspect of the present invention, a plunger is provided in a cylinder chamber formed in a housing and a spring for providing the plunger with an outwardly projecting property. The hydraulic oil is supplied into a pressure chamber formed at the back of the plunger, the pushing force applied to the plunger by the hydraulic oil is buffered, and the air remaining in the pressure chamber is exhausted to the outside by exhaust means. In the chain tensioner described above, a hole is formed as the exhaust means from the outer periphery of the housing to communicate with the pressure chamber, and a plug made of an air-permeable material is pressed into the hole.

According to the second aspect of the present invention, a plunger and a spring for providing the plunger with an outwardly projecting property are incorporated in a cylinder chamber formed in a housing, and the plunger is provided in a pressure chamber formed in a back portion of the plunger. In a chain tensioner configured to supply hydraulic oil, buffer a pushing force applied to the plunger by the hydraulic oil, and exhaust air remaining in the pressure chamber to the outside by an exhaust means, the plunger may be used as the exhaust means. In this configuration, an axial hole communicating with the pressure chamber from the tip end surface is formed, and a plug made of an air-permeable material is pressed into the hole.

Further, in the third aspect of the present invention, a plunger and a spring for imparting outward projection to the plunger are incorporated in a cylinder chamber formed in the housing, and the plunger is provided in a pressure chamber formed in the back of the plunger. In a chain tensioner configured to supply hydraulic oil, buffer a pushing force applied to the plunger by the hydraulic oil, and exhaust air remaining in the pressure chamber to the outside by an exhaust means, the plunger may be used as the exhaust means. Is made of an air-permeable material.

In the first to third inventions, examples of the air-permeable material include a porous material made of a sintered metal, ceramic or resin having fine communicating cells.

[0015] As in the first and second inventions, a plug made of an air-permeable material is press-fitted into a hole communicating between the pressure chamber and the outside, or, as in the third invention, the plunger is passed through the air-permeable member. Since it is possible to eliminate the need for screw processing or spiral groove processing by forming the conductive material, the cost of the chain tensioner can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a first embodiment of a chain tensioner according to the present invention. As shown, a cylinder chamber 2 is formed in a housing 1, and a plunger 3 is slidably incorporated in the cylinder chamber 2.

An oil supply passage 5 communicating with a pressure chamber 4 formed in the back of the plunger 3 is formed in the housing 1.
A check valve 6 is incorporated at the oil outlet side of the oil supply passage 5.

The check valve 6 is connected to a valve seat 7 incorporated in the closed end of the cylinder chamber 2 by an oil supply passage 5 and a pressure chamber 4.
Is formed, and a seat surface 9 is provided in the middle of the passage 8, and the amount of opening and closing of the check ball 10 that can be brought into contact with and separated from the seat surface 9 is restricted by a retainer 11. The check valve 6 is opened when the pressure in the pressure chamber 4 is reduced to allow the hydraulic oil sent to the oil supply passage 5 to flow into the pressure chamber 4, and is closed when the pressure in the pressure chamber 4 becomes high, and is closed. 4 prevents the working oil in 4 from flowing back to the oil supply passage 5.

The plunger 3 has a rod insertion hole 12 which is open at the rear end face. A female screw 13 is formed on the inner periphery of the open end of the rod insertion hole 12, and a male screw 15 formed on the outer periphery of the screw rod 14 is screwed to the female screw 13.

The screw rod 14 has a spring receiving hole 16 formed of a stepped hole penetrating from the front end surface to the rear end surface.
A spring 17 for providing the plunger 3 with an outward protruding property and a spring seat 18 are incorporated in the spring receiving hole 16.

The thread of the internal thread 13 formed on the plunger 3 and the external thread 15 formed on the outer periphery of the screw rod 14 have the flank angle of the pressure side flank 19 receiving the pushing force applied to the plunger 3 and the play side flank 20. And a lead angle at which the plunger 3 moves in the axial direction while being rotated by the elastic force of the spring 17 is provided on the serrated thread.

In the chain tensioner having the above structure, the unillustrated chain is pressed by the plunger 3 provided with the outward projecting property by the elastic force of the spring 17, and when the chain becomes loose, the spring 17 The plunger 3 is moved outward by the elastic force while rotating to absorb the slack of the chain.

At this time, since the pressure in the pressure chamber 4 decreases, the check valve 6 is opened, and hydraulic oil is supplied from the oil supply passage 5 into the pressure chamber 4.

On the other hand, when the plunger 3 is pushed in due to the tension of the chain, the check valve 6 is closed, and the pushing force applied to the plunger 3 by the working oil sealed in the pressure chamber 4 is buffered. If the pushing force is stronger than the elasticity of the spring 17, the hydraulic oil in the pressure chamber 4 leaks outside from between the sliding surfaces of the cylinder chamber 2 and the plunger 3, and
The plunger 3 rotates and retreats to a position where the pushing force and the elasticity of the spring 17 are balanced.

When the engine is stopped, the chain may be tensioned due to the stop position of the cam provided on the camshaft. At this time, the plunger 3 is pushed by the chain, but the pushing force is a static load, and the pushing force is received by the pressure side flank 19 in the screw engagement portion between the female screw 13 and the male screw 15, and the plunger 3 is pushed.
Does not retreat.

For this reason, even if the engine is restarted, the slack of the chain is extremely small, and the plunger 3 does not protrude largely outward. Therefore, the pressure drop in the pressure chamber 4 is small, and there is no inconvenience that air enters the pressure chamber 4.

As described above, when the engine is started, the outward movement of the plunger 3 is small, and the pressure chamber 4
Although air hardly enters the inside, there is a case where air is entrained in the hydraulic oil supplied to the oil supply passage 5 and is sent into the pressure chamber 4 together with the hydraulic oil. Further, air dissolved in the hydraulic oil may precipitate from the hydraulic oil due to a sudden drop in pressure. If the air stays in the pressure chamber 4, when the plunger 3 moves backward, the plunger 3 compresses the air, so that the damper effect is reduced and the function as a chain tensioner cannot be exhibited.

In order to eliminate such inconvenience, the air in the pressure chamber 4 is discharged to the outside by the exhaust mechanism 21. Here, as the exhaust mechanism 21, a hole 22 communicating with the pressure chamber 4 is formed from the upper part of the outer periphery of the housing 1. When the pressure in the pressure chamber 4 is increased, the air in the pressure chamber 4 flows through the inside of the plug 23 and is discharged to the outside.

Examples of the air-permeable material include a porous material made of sintered metal, ceramic or resin having fine communicating cells.

As described above, since the plug 23 made of an air-permeable material is press-fitted into the hole 22 communicating the pressure chamber 4 with the outside, threading and spiral groove machining can be eliminated. The cost of the chain tensioner can be reduced.

Here, when the plug 23 made of a sintered metal is employed, the sintered metal is less brittle than the ceramic, so that the sintered metal can be easily pressed into the hole 22 and has an elastic modulus as compared with the resin. Since it is low, a strong attachment state can be obtained.

FIG. 2 shows a second embodiment of the chain tensioner according to the present invention. In the chain tensioner shown in this embodiment, a plunger 33 and a spring 34 for giving the plunger 33 an outward protruding property are incorporated in a cylinder chamber 32 formed in a housing 31. A check valve 37 is provided on the oil outlet side of the oil supply passage 36 to prevent the hydraulic oil in the pressure chamber 35 from flowing back to the oil supply passage 36 side. Is provided.

A plurality of engagement grooves 38 are formed on the outer periphery of the plunger 32 at intervals in the axial direction, while the housing 31 has a clip holding groove 39 on the inner periphery of the opening of the cylinder chamber 32, A notch portion 40 is provided in the portion, and a ring portion 41a capable of expanding the diameter of the register clip 41 is incorporated into the clip holding groove 39. It is inserted and exposed to the outside.

Here, the inner surface of the engaging groove 38 is formed of a stopper surface 38a substantially perpendicular to the axis of the plunger 33 and a tapered surface 38b having a smaller diameter on the stopper surface 38a side.

In the chain tensioner having the above structure, the pushing force applied to the plunger 33 from the chain is buffered by the working oil sealed in the pressure chamber 35, and the plunger 33 is advanced by the pressing of the spring 34 to move the chain. It is designed to absorb slack.

When the chain is stretched, the plunger 33 is moved by an amount corresponding to the pitch of the engagement groove 38 to change the position of the engagement groove 38 with respect to the ring portion 41a of the register clip 41 to change the position of the chain. I try to absorb the growth.

In the chain tensioner as well, since the damper effect is reduced when air stays in the pressure chamber 35, the exhaust mechanism 21 is provided to exhaust the air to the outside.

As the exhaust mechanism 21, an axial hole 24 is formed in the plunger 33 so as to communicate with the pressure chamber 35 from the distal end face, and a flanged plug 25 made of an air-permeable material is press-fitted into the hole 24. When the pressure in the pressure chamber 35 rises due to the retreat of the plunger 33, the air in the pressure chamber 35 is discharged to the outside.

As the air permeable material, a porous material made of sintered metal, ceramic or resin is used.

In the chain tensioner according to the second embodiment as well, screw processing and spiral groove processing can be omitted, so that the cost of the chain tensioner can be reduced.

FIG. 3 shows a third embodiment of the chain tensioner according to the present invention. The chain tensioner of this embodiment differs from the chain tensioner of the first embodiment shown in FIG. 1 only in the exhaust mechanism 21. The exhaust mechanism 21 according to the third embodiment forms the plunger 3 from an air-permeable material, and when the pressure in the pressure chamber 4 rises due to the retreat of the plunger 3, the air remaining in the pressure chamber 4 is plunged. The system is designed to be discharged from the inside of the third organization.

Here, a porous material made of a sintered metal is employed as the air-permeable material.

In the third embodiment, since it is not necessary to drill holes or press-fit the plugs, the cost of the chain tensioner can be further reduced.

[0044]

The present invention is configured as described above.
The following effects are obtained.

According to the first and second aspects of the present invention, a plug made of an air-permeable material is press-fitted into a hole communicating between the pressure chamber and the outside. In addition, the air generated can be exhausted to the outside, and screw processing and spiral groove processing can be omitted, so that the cost of the chain tensioner can be reduced.

According to the third aspect of the present invention,
Since the plunger is formed of an air-permeable material, it is not necessary to form a hole or install a plug, so that the cost of the chain tensioner can be further reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of a chain tensioner according to the present invention;

FIG. 2 is a longitudinal sectional front view showing a second embodiment of the chain tensioner according to the present invention;

FIG. 3 is a longitudinal sectional front view showing a third embodiment of the chain tensioner according to the present invention;

FIG. 4 is a longitudinal sectional front view showing a conventional chain tensioner.

FIG. 5 is a longitudinal sectional front view showing another conventional chain tensioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Cylinder chamber 3 Plunger 4 Pressure chamber 5 Oil supply passage 6 Check valve 17 Spring 21 Exhaust mechanism 22 Hole 23 Plug body 24 Hole 25 Plug body 31 Housing 32 Cylinder chamber 33 Plunger 34 Spring 35 Pressure chamber 36 Oil supply passage 37 Check valve

Claims (5)

[Claims] 1. An oil supply passage which incorporates a plunger slidable into a cylinder chamber formed in a housing and a spring for pressing the plunger outward, and which communicates with a pressure chamber formed in a back portion of the plunger in the housing. A check valve is provided on the oil outlet side of the oil supply passage to prevent hydraulic oil in the pressure chamber from flowing back to the oil supply passage side,
In a chain tensioner configured to cause air remaining in the pressure chamber to be exhausted to the outside via an exhaust means when the pressure in the pressure chamber into which the plunger is pushed is increased, the exhaust means includes a hole communicating from the outer periphery of the housing to the pressure chamber. A chain tensioner formed by press-fitting a plug made of an air-permeable material into the hole. 2. A refueling passage which incorporates a plunger slidable into a cylinder chamber formed in a housing and a spring which presses the plunger outward, and the housing communicates with a pressure chamber formed on the back of the plunger. A check valve is provided on the oil outlet side of the oil supply passage to prevent hydraulic oil in the pressure chamber from flowing back to the oil supply passage side,
In a chain tensioner configured to exhaust air accumulated in the pressure chamber to the outside through an exhaust unit when the pressure in the pressure chamber into which the plunger is pushed rises, the exhaust unit communicates with the plunger from the distal end surface to the pressure chamber. A chain tensioner having a structure in which an axial hole is formed, and a plug made of an air-permeable material is pressed into the hole. 3. An oil supply passage which incorporates a plunger slidable into a cylinder chamber formed in a housing and a spring for pressing the plunger outward, and the housing communicates with a pressure chamber formed in a back portion of the plunger. A check valve is provided on the oil outlet side of the oil supply passage to prevent hydraulic oil in the pressure chamber from flowing back to the oil supply passage side,
A chain tensioner in which, when the pressure in the pressure chamber into which the plunger is pushed rises, air remaining in the pressure chamber is exhausted to the outside via an exhaust means, the exhaust means is formed by forming the plunger from an air-permeable material. A chain tensioner characterized by being formed. 4. The chain tensioner according to claim 1, wherein the air-permeable material is made of a sintered metal. 5. The chain tensioner according to claim 1, wherein the air-permeable material is made of a porous material made of ceramic or resin.