JP2000291749A - Chain tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the assemblability and prevent the dropping of components of a damper mechanism in the maintenance in accompany with the removement of a chain by unifying an inner cylindrical part and the damper mechanism by mounting an antislipping-off means for limiting the moving amount of a plunger between the inner cylindrical part and the plunger. SOLUTION: An antislipping-off mechanism 35 for detenting a plunger 22 and limiting the outward projection amount of the plunger 22, is mounted between an inner cylindrical part 13 and the plunger 22, and the inner cylindrical part 13 and a damper mechanism 21 are unified by this antislipping-off mechanism 35. The antislipping-off mechanism 35 is formed by forming a groove 36 on an outer perphery of the plunger 22 from a point to an axial intemediate part of the plunger 22, a stopper 37 to be inserted into the groove 36 is formed on an opening end of the inner cylindrical part 13 by folding, and the plunger 22 is prevented from being slipped off by contacting an end part 36a with a stopper 37. Whereby a chain tensioner can be easily assembled and the assembling can be automized.

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 camshaft driving chain.

[0002]

2. Description of the Related Art A chain tensioner shown in FIG. 7 is known as a chain tensioner for maintaining a constant tension of a chain for driving a camshaft. This chain tensioner has a housing 60
A plunger 62 and a spring 63 are incorporated into a cylinder chamber 61 formed in the cylinder 6.
4 is pressed.

[0003] An oil supply passage 66 communicates with a pressure chamber 65 formed at the back of the plunger 62.
When the plunger 62 moves outward and the pressure in the pressure chamber 65 decreases, the check valve 67 is opened, and oil is flowed from the oil supply passage 66 to the pressure chamber 65 by driving the oil supply pump. I try to make it.

In a camshaft driving chain, when the engine is stopped, the chain 64 may be held in a tensioned state due to a stop position of a cam provided on the camshaft. In this case, since the plunger 62 of the chain tensioner is pushed by the tensioned chain 64, the oil in the pressure chamber 65 leaks from the sliding surface between the plunger 62 and the cylinder chamber 61, and the plunger 62 retreats, It is held at a position where the elasticity and the tension of the spring 63 are balanced.

For this reason, when the chain 64 is slackened due to the restart of the engine, the plunger 62 largely moves outward. At this time, since the hydraulic pump has just started and the discharge amount is small, it is impossible to supply sufficient oil to the pressure chamber 65, and air enters the pressure chamber 65, damping characteristics are reduced, and abnormal noise is generated. May occur.

Also, at the time of low temperature starting, the viscosity of the oil is high,
Poor fluidity causes the same problems as described above.

In order to solve the above-mentioned problems, a rod insertion hole is formed in the plunger at the rear end face thereof, and a female screw provided on the inner periphery of the opening of the rod insertion hole is formed on the outer periphery of the screw rod. The present patent application filed a chain tensioner in which a male screw and a female screw were engaged with each other, the threads of the male screw and the female screw were formed in a sawtooth shape, and a spring was incorporated between the opposed portions of the plunger and the screw rod to press both members in opposite directions. One has already proposed (Japanese Patent Application No. 9-71947).

In the above chain tensioner, when the engine is stopped and the chain is tensioned due to the cam stop position and a pushing force is applied to the plunger, the pushing force is received by the pressure side flank of the serrated thread. This prevents the plunger from retreating. For this reason, even if the engine is restarted and the slack occurs, the amount of the slack is small, so that the plunger does not largely move outward, thereby preventing the air from entering the pressure chamber. are doing.

[0009]

By the way, in the chain tensioner which has been already proposed, the components of the damper mechanism for absorbing the change in the tension of the chain are relatively large, such as a plunger, a screw rod and a spring. It is necessary to sequentially insert the parts into the cylinder chamber and screw-engage the screw rod and the plunger, so that assembling is troublesome, and there is still a point to be improved in improving the assemblability.

In addition, the inner diameter surface of the cylinder chamber needs to be processed with relatively high precision in order to smoothly slide the plunger, and there is still a point to be improved in reducing the processing cost.

Further, at the time of maintenance around the engine for removing the chain, the plunger jumps out of the cylinder chamber due to the elasticity of the spring, and parts such as the screw rod and the spring are disassembled. Because there is a risk of making mistakes, it is necessary to take measures to prevent such mistakes.

SUMMARY OF THE INVENTION It is a technical object of the present invention to improve the assemblability of a chain tensioner having a damper mechanism and to prevent components of the damper mechanism from falling off during maintenance for removing the chain.

[0013]

In order to solve the above-mentioned problems, according to the present invention, a housing is provided with a cylinder chamber and an oil supply passage opening at a closed end of the cylinder chamber, and a chain is provided in the cylinder chamber. A damper mechanism for absorbing a change in tension of the chain tensioner, the damper mechanism having a plunger slidably inserted into the cylinder chamber, wherein the chain is pressed by the plunger. And an inner cylinder portion having a cylinder chamber inside,
A structure is provided between the inner cylinder and the plunger, in which a stopper is provided to limit the amount of outward movement of the plunger, and the inner cylinder and the damper mechanism are unitized.

As the damper mechanism, a plunger slidably inserted into the cylinder chamber of the inner cylinder portion, a screw rod screwed to the rear end of the plunger, and the screw rod connected to the closed end of the cylinder chamber. And a spring that presses toward the front end.

[0015] As means for retaining the plunger,
A groove may be formed on the outer peripheral surface of the plunger from the tip to the middle of the plunger in the axial direction, and a stopper may be provided at the open end of the inner cylinder portion to be inserted into the groove.

As described above, since the inner cylinder portion and the damper mechanism are unitized, the assembly of the chain tensioner can be performed only by inserting the assembly unit of the inner cylinder portion and the damper mechanism into the outer cylinder portion. Thus, the chain tensioner can be easily assembled, and the assembly can be automated.

Here, by adopting a press-formed sleeve with a bottom made of shell as the inner cylinder portion, a cylinder chamber with good inner surface accuracy can be obtained. Processing can be eliminated, and cost can be reduced.

Further, if a retaining means is provided between the outer cylinder and the inner cylinder, it is possible to prevent the inner cylinder from dropping off when the chain tensioner is assembled. is there.

As the retaining means, a bent piece is formed at the opening end of the inner cylinder portion, which is directed in the outer diameter direction, and this bent piece is inserted into a notch provided at the opening end of the outer cylinder portion. The bent piece can be prevented from coming off by caulking both side edges of the portion.

Here, a flat surface is formed on the outer periphery of the plunger to form a step in the middle of the outer periphery, and a radial pin hole is formed at the open end of the outer cylinder portion and the inner cylinder portion. By inserting a retaining pin into the plunger and making the tip end face the stepped portion in the axial direction of the plunger, the plunger can be retained and the inner cylinder can be retained with a single pin. The structure of the chain tensioner can be simplified.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a chain 5 is stretched between a sprocket 2 attached to an end of a crankshaft 1 and a sprocket 4 attached to an end of a camshaft 3, and a slack side of the chain 5 The slipper 6 is in contact with the chain 5a. The slipper 6 is supported swingably about a shaft 7. The slipper 6 is pressed by the chain tensioner 10, and the pressing keeps the chain 5 at a constant tension.

FIGS. 2A and 2B show the details of the chain tensioner 10. FIG. The chain tensioner 10 includes a housing 11 and a damper mechanism 21 incorporated in the housing 11.

The housing 11 includes an outer cylinder 12 and an inner cylinder 1.
And a screw hole 15 closed by screwing the plug 14 into the closed end of the outer cylindrical portion 12. An oil supply passage 16 is formed at the closed end of the outer cylinder 12.

The inner cylindrical portion 13 is formed of a bottomed sleeve formed by press-forming a thin steel plate. A hole 18 communicating with the oil supply passage 16 is provided in a bottom 13a of the inner cylindrical portion 13, and a peripheral portion of the hole 18 is tapered.

An outward bent piece 1 is provided at the opening edge of the inner cylindrical portion 13.
9 is formed, and the bent piece 19 is inserted into a notch 20 provided at the opening end of the outer cylinder 12, and the inner cylinder 13 is prevented from rotating by crimping both side edges of the notch 20. ,
And it is locked.

The damper mechanism 21 has a plunger 22 for pressing the chain, a screw rod 23 screwed to the rear end of the plunger 22, and presses the screw rod 23 toward the closed end of the cylinder chamber 17. And a spring 24.

The plunger 22 is slidably inserted into the cylinder chamber 17. The plunger 22 has a rod insertion hole 25 that opens at the rear end face, and a female screw 26 is provided on the inner periphery of the opening of the rod insertion hole 25.

The screw rod 23 has a male screw 27 on the outer periphery which is screwed to the female screw 26. The thread of the female screw 26 and the male screw 27 is formed by a pressure flank 28 which receives a pushing force when the plunger 22 is pushed in the axial direction.
Has a flank angle larger than the flank angle of the play-side flank 29, and the lead angle at which the screw rod 23 rotates toward the closed end of the cylinder chamber 17 while being rotated by the pressing of the spring 24 on the serrated thread. Is provided.

The screw rod 23 has a spring receiving hole 30, an oil passage 31, and a wrench engaging hole 32 formed on the axis thereof. The spring 24 and the spring seat 33 are incorporated in the spring receiving hole 30. ing.

The damper mechanism 21 incorporated in the cylinder chamber 17 of the inner cylinder portion 13 is provided with an outward projecting property by a spring 34 incorporated in the cylinder chamber 17. When a check valve is separately provided, the spring 34 may be omitted.

Between the inner cylindrical portion 13 and the plunger 22, there is provided a retaining mechanism 35 for preventing the plunger 22 from rotating and restricting the amount of outward projection. The cylinder 13 and the damper mechanism 21 are unitized.

The retaining mechanism 35 is provided on the outer periphery of the plunger 22 with a groove 36 extending from the tip to the middle of the plunger 22 in the axial direction.
A stopper 37 to be inserted into the groove 36 is formed at the open end of the inner cylindrical portion 13 by bending, and the plunger 22 is prevented from coming off by the contact of the end 36a of the groove 36 with the stopper 37. are doing.

The chain tensioner 1 having the above structure
At the time of assembling, the assembly unit of the inner cylinder 13 and the damper mechanism 21 is inserted into the outer cylinder 12, and the bent piece 19 provided at the open end of the inner cylinder 13 is connected to the open end of the outer cylinder 12. After being inserted into the notch 20 formed in the above, the bent piece 19 is prevented from coming off by caulking both side edges of the notch 20.

As described above, since the chain tensioner 10 can be assembled by inserting the assembly unit into the outer cylindrical portion 12 and crimping both side edges of the cutout portion 20 after the insertion, the assembly is easy and easy. Also, automation of assembly is possible.

When attaching the chain tensioner 10 to the engine block, the plunger 22 is immersed in the inner cylinder 13, the immersion state is maintained, the outer cylinder 12 is attached to the engine block, and the plunger 22 is held. The plunger 22 is moved forward by the supply of hydraulic oil to the oil supply passage 16 and the pressing of the spring 34,
The plunger 22 presses the slipper 6 to push the chain 5
Nervous.

Here, when the plunger 22 is immersed, the plug 14 is removed, a wrench is inserted into the screw hole 15 to engage with the wrench engaging hole 32 of the screw rod 23,
The screw rod 23 is rotated by rotating the wrench with the tip of the plunger 22 lightly pressed, and the female screw 26 is rotated.
The plunger 22 is moved backward by the engagement of the external thread 27 with the plunger 22.

In holding the plunger 22 that has been retracted, in the embodiment, a pin hole 40 in the radial direction is formed at the open end of the housing 11, and a set pin 41 is inserted into the pin hole 40, and The step 22a formed at the tip is brought into contact with the set pin 41.

In the state where the chain tensioner 10 shown in FIG. 1 is mounted, when the engine is started and the sprocket 2 mounted on the end of the crankshaft 1 rotates in the direction of the arrow, the slack side chain 5a of the chain 5 loosens. The plunger 22 and the screw rod 23 move outward due to the pressure of the working oil sent from the oil supply passage 16, and the screw rod 23 moves away from the bottom of the inner cylindrical portion 13 due to the movement, whereby the working oil is supplied into the cylinder chamber 17. You.

The outward movement of the plunger 22 causes the plunger 22 to press the slipper 6, so that the slack of the chain 5 is absorbed, and the elasticity of the spring 24 rotates the screw rod 23 while rotating the cylinder. The chain 5 moves toward the closed end of the chamber 17 and abuts against the bottom of the inner cylindrical portion 13, and the chain 5 is maintained at a predetermined tension by stopping the plunger 22 and the screw rod 23.

When the temperature of the engine rises, the center distance between the crankshaft 1 and the camshaft 3 increases due to thermal expansion, and the plunger 22 is pressed by an increase in the tension of the chain 5, the pressing force is applied to the cylinder chamber 17. It is received by the enclosed oil, and the female screw 26 and the male screw 2
7, the plunger 22 does not retract. When the pressing force for pressing the plunger 22 becomes stronger than the combined force of the elasticity of the springs 24 and 34 and the hydraulic pressure, the screw rod 23 rotates and the plunger 22
Retreats.

At this time, the oil in the cylinder chamber 17 leaks from between the sliding surfaces of the cylinder chamber 17 and the plunger 22,
The plunger 22 slowly retreats to a position where the resultant force of the pressing force, the elasticity of the springs 24 and 34, and the supply oil pressure is balanced.

When the engine is stopped, the slack side chain 5a of the chain 5 may be tensioned due to the stop position of the cam provided on the camshaft 3. In this case, the plunger 22 is pressed by the chain 5, and the pressing force is received by the pressure side flank 28 in the screw engagement portion between the female screw 26 and the male screw 27.

Since the pressing force is a static load without vibration, the pressing force is applied to the springs 24, 34.
The screw rod 23 does not rotate and the plunger 22 does not retreat even if the elasticity is greater than

For this reason, even if the slack side chain 5a of the chain 5 is slackened due to the restart of the engine, the slack amount is extremely small, and the protrusion amount of the plunger 22 is also small. Therefore, since the pressure drop in the cylinder chamber 17 is small, no air enters the cylinder chamber 17.

When the engine is started at a low temperature, the viscosity of the oil sent from the pump to the oil supply passage 13 is high, and
Although the flow of the hydraulic oil into the pipe 7 is deteriorated, even in this case, since the amount of outward movement of the plunger 22 is small, it is possible to prevent air from entering the cylinder chamber 17.

A chain tensioner 10 as shown in FIG.
When the plunger 22 is used, the spring 2
4 and 34, the plunger 22 projects outward when the chain 5 is removed for maintenance around the engine, but the end of the groove 36 contacts the stopper 37. Because they come into contact with each other, they do not fall out of the cylinder chamber 17.

As a result, parts such as the screw rod 22 and the springs 24 and 34 are not disassembled into pieces and there is no need to reassemble. Therefore, it is possible to prevent forgetting or erroneous assembling of parts. it can.

When reproducing the use state of the chain tensioner 10, a wrench is inserted into the screw hole 15 as described above, the wrench tip is engaged with the wrench engaging hole 32 of the screw rod 23, and the wrench is rotated by a rotating operation. The plunger 22 is retracted.

FIGS. 3 to 5 show other examples of the retaining mechanism of the inner cylinder 13 and the plunger 22. Chain tensioner 10 shown in FIGS. 3 (I) and (II)
Then, a pin hole 50 is formed at the opening end of the outer cylindrical portion 12, a retaining pin 51 is inserted into the pin hole 50, and the inner cylindrical portion 13 is prevented from coming off by abutment of the stopper 37 against the retaining pin 51. In addition, the stopper 37 is prevented from falling outward.

In the chain tensioner 10 shown in FIGS. 4 (I) and (II), a flat surface 52 is formed on the outer peripheral surface of the plunger 22, and a step 52 a is provided in the middle of the outer periphery of the plunger 22. A pin hole 5 is provided at the opening end of the inner cylindrical portion 13.
3 is formed, and a retaining pin 54 is inserted into the pin hole 53 to prevent the inner cylindrical portion 13 from being removed and the plunger 22 from being removed.

In the chain tensioner 10 shown in FIGS. 5 (I) and (II), a retaining pin 55 with a seat is used instead of the retaining pin 54 shown in FIGS. 4 (I) and (II). .

As shown in FIG. 4 and FIG. 5, by using the retaining pins 54 and 55 to prevent the inner cylindrical portion 13 and the plunger 22 from coming off, the bent pieces shown in FIGS. Since the 19 and the notch 20 can be omitted, the configuration of the chain tensioner 10 can be simplified.

FIG. 6 shows another example of the chain tensioner according to the present invention. In this chain tensioner 10, the plunger 22 is formed with a cylindrical portion 22b and an internal thread 2
6 is divided into a nut portion 22c formed therein.

As described above, the plunger 22 is connected to the cylindrical portion 2.
2b and the nut portion 22c, the nut portion 22c can be formed by a machining method using a tap or a manufacturing method by sinter molding.
Because the tap can take incomplete thread part enough,
A high-precision female screw 26 can be formed.

Since the inner cylindrical portion 22b has a simple shape, it can be easily manufactured by forging.

[0057]

As described above, according to the present invention, the housing is formed by the outer cylinder and the inner cylinder, and the inner cylinder and the damper mechanism are unitized, so that the chain tensioner can be easily assembled. And automation of assembly can be made possible.

Further, at the time of maintenance for removing the chain, it is possible to prevent parts forming the damper mechanism from falling off.

Further, by using a shell made of press-formed shell as the inner cylinder part, it is possible to obtain a cylinder chamber with good surface accuracy of the inner diameter surface. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a use state of a chain tensioner according to the present invention.

FIG. 2 (I) is a cross-sectional view of the chain tensioner shown in FIG. 1, and (II) is a right side view of (I).

FIG. 3 (I) is a partially cutaway plan view showing another example of the chain tensioner according to the present invention, and (II) is aa of (I).
Sectional view along the line

FIG. 4I is a partially cutaway plan view showing another example of the chain tensioner according to the present invention, and FIG.
Sectional view along line b

FIG. 5 (I) is a partially cutaway plan view showing another example of the chain tensioner according to the present invention, and (II) is a c- line of (I).
Sectional view along line c

FIG. 6 is a partially cutaway plan view showing still another example of the chain tensioner according to the present invention.

FIG. 7 is a sectional view showing a conventional chain tensioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Housing 12 Outer cylinder part 13 Inner cylinder part 14 Plug 15 Screw hole 16 Oil supply passage 17 Cylinder chamber 19 Bent piece 20 Notch part 21 Damper mechanism 22 Plunger 23 Screw rod 24 Spring 26 Female screw 27 Male screw 32 Wrench engaging hole 35 Mechanism 36 Groove 37 Stopper 52 Flat surface 52a Step 53 Pin hole 54, 55 Retaining pin

Claims (7)

[Claims] A housing provided with a cylinder chamber and an oil supply passage opening at a closed end of the cylinder chamber; a damper mechanism for absorbing a change in tension of a chain provided in the cylinder chamber; A chain tensioner having a plunger slidably inserted in the chain tensioner, wherein the plunger presses the chain. In the chain tensioner, the housing includes an outer cylinder portion and an inner cylinder portion having a cylinder chamber inside. A chain tensioner, wherein a stopper is provided between a cylinder and the plunger to limit the amount of outward movement of the plunger, and the inner cylinder and the damper mechanism are unitized. 2. The plunger slidably inserted into a cylinder chamber of the inner cylinder, a screw rod screwed to a rear end of the plunger, and a screw rod of the cylinder chamber. 2. The chain tensioner according to claim 1, further comprising a spring that presses toward the closed end. 3. The chain tensioner according to claim 2, wherein the inner cylinder portion is formed by a press-formed shell-made bottomed sleeve. 4. The plunger retaining means forms a groove in the outer peripheral surface of the plunger from the tip to the middle of the plunger in the axial direction, and a stopper inserted into the groove at the open end of the inner cylindrical portion. The chain tensioner according to any one of claims 1 to 3, wherein the chain tensioner is provided. 5. The chain tensioner according to claim 1, further comprising means for preventing the inner cylinder from falling off between the outer cylinder and the inner cylinder. 6. The retaining means forms a bent piece at the opening end of the inner cylinder part in an outer radial direction, and inserts the bent piece into a notch provided at the opening end of the outer cylinder part. 6. The chain tensioner according to claim 5, wherein the bent piece is prevented from coming off by caulking both side edges of the notch. 7. A stopper for the plunger, wherein a flat surface is formed on the outer periphery of the plunger to form a step in the middle of the outer periphery, and a radial pin is provided on the open end of the outer and inner cylinders. The chain tensioner according to any one of claims 1 to 3, wherein a hole is formed, a retaining pin is inserted into the pin hole, and a distal end portion is opposed to the step portion in the axial direction of the plunger. .