JP4243793B2 - Chain tensioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chain tensioner that keeps the tension of a chain such as a camshaft drive chain constant.
[0002]
[Prior art]
As this type of chain tensioner, a cylinder chamber is formed in a housing attached to an engine block, a plunger and a spring that presses the plunger outward are incorporated in the cylinder chamber, and the housing is formed on the back of the plunger. An oil supply passage communicating with the pressure chamber is provided, the chain is pressed by the plunger, and the pushing force applied to the plunger from the chain is buffered by the hydraulic oil in the pressure chamber to keep the chain tension constant. Things are conventionally known.
[0003]
Incidentally, as described above, in the chain tensioner that buffers the pushing force applied to the plunger by the hydraulic oil enclosed in the pressure chamber, the pressure of the hydraulic oil in the pressure chamber may be higher than necessary. In this case, the reaction force with which the plunger presses the chain becomes too large, the chain tension becomes excessively high, the chain wears out quickly, or noise is generated, and sometimes the chain may be broken by abnormal tension. was there.
[0004]
In order to prevent such inconvenience, the pressure chamber communicates with the outside through an oil drainage passage, and a relief valve is incorporated in the oil drainage passage, so that the hydraulic oil pressure in the pressure chamber is higher than the set pressure. There has been proposed a chain tensioner that prevents this from happening (see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-325202 (page 6, FIG. 3)
[0006]
Here, in the relief valve, a cap is attached to the opening end of the flanged sleeve, and a valve body for opening and closing the valve hole and a spring for pressing the valve body in the closing direction are incorporated in the flanged sleeve. Because it is an assembled product, it can be easily assembled to the chain tensioner, and the valve opening pressure can be measured at the stage before the relief valve is assembled. Therefore, it is possible to provide a chain tensioner with stable quality. It has the feature that it can.
[0007]
[Problems to be solved by the invention]
By the way, in the chain tensioner described in Patent Document 1, since the relief valve is pressed against the valve contact portion of the oil discharge passage by a spring that presses the plunger outward, the stability of the relief valve is poor. When the valve reciprocates at a high speed, the relief valve also finely moves and repeatedly collides with the valve abutting part, generating vibrations and noise, and the hydraulic oil in the pressure chamber contacts the valve between the relief valve and the oil discharge passage. There is an inconvenience that the damper effect is reduced due to leakage to the outside from the gap formed between the parts.
[0008]
In addition, since the relief valve has a cap fixed by caulking the open end of the flanged sleeve, it takes time to assemble the relief valve and has a disadvantage of high cost.
[0009]
An object of the present invention is to provide a chain tensioner that improves the assembly performance of a relief valve, reduces costs, and generates less vibration and noise.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, a plunger that is slidable in a cylinder chamber formed in the housing and a spring that presses the plunger outward are incorporated, and the housing is mounted on the back of the plunger. An oil supply passage communicating with the formed pressure chamber is provided, and when the pressure of the hydraulic oil in the pressure chamber exceeds the set pressure, the hydraulic oil in the pressure chamber is discharged to the drain oil passage communicating with the pressure chamber. In a chain tensioner incorporating a relief valve to be operated, the relief valve has a valve body comprising a sleeve having a press-molded end plate and a cap press-fitted into the open end of the sleeve , and the valve body said cap to provide a valve hole communicating with the oil inlet side of the drain oil passage, the discharge hole communicating with the oil outlet of the oil discharge passage to said sleeve Provided, a valve body for the valve hole opened and closed in the valve within the body, the valve element incorporating a spring for pressing in the closing direction made assembly, the relief valve of the stepped formed oil discharge passage The structure fixed in the valve insertion hole was adopted.
[0011]
As described above, the valve body of the relief valve and the cap for preventing the spring from being removed are attached by press-fitting, so that the relief valve can be easily assembled and the cost of the relief valve can be reduced.
[0012]
Further, by fixing the relief valve in the oil discharge passage, it is possible to prevent the relief valve from moving due to the pressure fluctuation of the hydraulic oil in the pressure chamber. For this reason, vibration and noise do not occur, and the hydraulic oil in the pressure chamber does not leak to the outside from the oil discharge passage when the relief valve is closed, and the reduction of the damper effect can be suppressed.
[0013]
Here, the responsiveness of the relief valve can be enhanced by providing the relief valve with a limiting means for limiting the opening / closing amount of the valve element. As the limiting means, a method of providing a rod integrally with the cap or a method of providing a rod between the cap and the valve body can be employed.
[0014]
Moreover, the cost of the relief valve can be further reduced by using the relief valve sleeve as a press-molded product.
[0015]
As a means for fixing the relief valve, a screw hole is formed on the valve insertion side of the valve insertion hole formed in the oil drainage passage, and the relief valve is tightened with a set screw engaged with the screw hole. a method of pressing the stepped portion to form a retainer fitting hole in the valve insertion side of the bulb inserting hole, and press fitting the apertured retainer to the retainer fitting hole, how pressing the relief valve with the stepped portion of the valve insertion hole it can be adopted.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment of a chain tensioner according to the present invention. As shown in FIG. 1, a cylinder chamber 2 having a closed end is formed in a housing 1 attached to an attachment target such as an engine block, and a plunger 3 is slidably incorporated in the cylinder chamber 2.
[0017]
The plunger 3 has a hollow chamber 4 opened at the rear end surface, and a spring 5 incorporated between the closed end of the hollow chamber 4 and the closed end of the cylinder chamber 2 presses the plunger 3 outward. .
[0018]
The housing 1 is provided with an oil supply passage 7 communicating with a pressure chamber 6 formed in the back portion of the plunger 3. A check valve 8 is incorporated on the oil outlet side of the oil supply passage 7. When the pressure of the hydraulic oil in the pressure chamber 6 becomes higher than the pressure in the oil supply passage 7, the check valve 8 closes the oil supply passage 7 to prevent the hydraulic oil in the pressure chamber 6 from flowing into the oil supply passage 7.
[0019]
Between the housing 1 and the plunger 3, there is provided a backward movement regulating mechanism 10 that prevents the plunger 3 from moving backward by a predetermined amount toward the closed end of the cylinder chamber 2.
[0020]
As shown in FIGS. 1 and 4, the backward movement restricting mechanism 10 has a clip housing groove 11 formed in the inner periphery of the opening of the cylinder chamber 2, and the radial direction provided in the register clip 12 in the clip housing groove 11. A ring portion 12 a that can be elastically deformed is accommodated, and a plurality of circumferential grooves 13 that are fastened by the ring portion 12 a are provided at equal intervals in the axial direction on the outer peripheral portion of the plunger 3. 3 is provided with a taper surface 13a having a small diameter toward the tip of 3 and an engagement surface 13b at the small diameter end of the taper surface 13a.
[0021]
In the backward movement restricting mechanism 10 configured as described above, the taper surface 13a allows the plunger 3 to move forward by the action of expanding the ring portion 12a of the register clip 12, and abuts against the rear wall surface 11a of the clip housing groove 11. The retraction movement of the plunger 3 is restricted by the engagement of the engagement surface 13b with the ring portion 12a of the register clip 12 that stops.
[0022]
As shown in FIGS. 1 to 3, the housing 1 is formed with an oil discharge passage 20 that allows the pressure chamber 6 to communicate with the outside. The oil drainage passage 20 includes a stepped valve insertion hole 20a communicating with the pressure chamber 6, a valve insertion side of the valve insertion hole 20a, a screw hole 20b larger in diameter than the valve insertion hole 20a, and a side surface of the housing 1. The oil drain hole 20c is open and communicates with the end of the screw hole 20b.
[0023]
A relief valve 30 is incorporated in the valve insertion hole 20a to open and discharge the hydraulic oil to the outside when the pressure of the hydraulic oil in the pressure chamber 6 exceeds a set pressure. The relief valve 30 is fixedly attached by being pressed against the step portion 21 of the valve insertion hole 20a by tightening a set screw 40 screwed into the screw hole 20b.
[0024]
As shown in FIG. 3, the relief valve 30 is composed of an assembly in which a valve body 34 and a spring 35 are assembled in a valve body 33 in which a cap 32 is press-fitted into an open end portion of a sleeve 31 having an end plate. The valve body 33 is formed with a valve hole 36 communicating with the oil inlet side of the oil discharge passage 20 and a discharge hole 37 communicating with the oil discharge hole 20 c of the oil discharge passage 20.
[0025]
The valve body 34 opens and closes the valve hole 36, and the spring 35 presses the valve body 34 in the closing direction.
[0026]
The chain tensioner shown in the embodiment has the above-described structure. FIG. 1 shows the shaft 52 around the shaft 52 by the plunger 3 that fixes the housing 1 to the engine block and is given the outward projecting property by the elasticity of the spring 5. A state is shown in which the chain guide 51 supported so as to be swingable is pressed against the camshaft drive chain 53 to hold the chain 53 in a tensioned state.
[0027]
In the tension adjustment state of the chain 53 as described above, if the chain 53 vibrates due to a change in the angular velocity during one rotation of the crankshaft or a torque fluctuation of the camshaft, and the chain 53 becomes slack, the plunger 5 is caused by the elasticity of the spring 5. 3 moves outward to absorb the slack of the chain 53.
[0028]
Here, when elongation occurs in the chain 53 and the slackness of the chain 53 is large, the ring portion 12a of the register clip 12 is pushed by the taper surface 13a of the circumferential groove 13 of the plunger 3 that moves forward to expand the diameter. For this reason, the plunger 3 continues to move forward and absorbs the slackness of the chain 53, and the ring portion 12 a of the register clip 12 fits into the next circumferential groove 13.
[0029]
On the other hand, when the chain 53 is tensioned, a pushing force is applied to the plunger 3 through the chain guide 51, and the pushing force is buffered by the hydraulic oil in the pressure chamber 6.
[0030]
When the pressure in the pressure chamber 6 rises abnormally and the pressure exceeds the set pressure of the relief valve 30, the relief valve 30 is opened, and the hydraulic oil in the pressure chamber 6 is discharged to the outside from the oil discharge passage 20. . For this reason, the tension of the chain 53 does not rise abnormally, and wear of the chain 53 and generation of abnormal noise can be suppressed.
[0031]
Here, since the relief valve 30 is fixedly mounted, it does not move in the axial direction even if the hydraulic oil in the pressure chamber 6 fluctuates due to the reciprocation of the plunger 3. For this reason, noise and vibration are not generated, and there is no inconvenience that hydraulic oil in the pressure chamber 6 leaks outside from the oil drain passage 20 when the relief valve 30 is closed, and the damper effect is reduced. Can be prevented.
[0032]
Further, the relief valve 30 is an assembly in which the valve body 34 and the spring 35 are assembled in the valve body 33, so that the relief valve 30 can be easily assembled in the oil drainage passage 20, and is set in a stage before the assembly. Since the pressure can be measured, a chain tensioner with stable quality can be provided.
[0033]
Further, since the valve body 33 has a configuration in which the cap 32 is press-fitted into the opening end portion of the sleeve 31, it is easy to assemble and the cost of the relief valve 30 can be reduced.
[0034]
Here, if the sleeve 31 is a press-molded product, mass production is possible, and the cost of the relief valve 30 can be further reduced.
[0035]
FIG. 5 shows another example of the relief valve 30. The relief valve 30 shown in this example is different from the relief valve 30 shown in FIG. 3 in that a rod 43 for limiting the opening / closing amount of the valve body 34 is incorporated in the valve body 33. For this reason, the same components as those of the relief valve 30 shown in FIG.
[0036]
Also in the relief valve 30 shown in FIG. 5 , the responsiveness can be improved.
[0037]
6 and 7 show a second embodiment of the chain tensioner according to the present invention. In the chain tensioner shown in the second embodiment, a drain oil passage 22 that communicates the pressure chamber 6 and the outside is formed at the closed end of the plunger 3, and a relief valve 30 is incorporated and fixed in the oil drain passage 22. This is different from the chain tensioner shown in the first embodiment.
[0038]
For this reason, the same code | symbol is attached | subjected to the components same as the chain tensioner shown in 1st Embodiment, and description is abbreviate | omitted.
[0039]
Here, the oil drainage passage 22 formed in the plunger 3 includes a stepped valve insertion hole 22a and a retainer fitting hole 22b formed on the valve insertion side of the valve insertion hole 22a. The relief valve 30 inserted into the valve insertion hole 22a is pressed against the step portion 24 of the valve insertion hole 22a by the perforated retainer 23 press-fitted into the hole 22b so that the relief valve 30 is fixed.
[0040]
As described above, by fixing the relief valve 30 with the retainer 23 that is press-fitted into the retainer fitting hole 22b, the relief valve 30 can be easily fixed, and the assembly of the chain tensioner can be facilitated.
[0041]
As shown in FIG. 8, on the valve insertion side of the valve insertion hole 22a, a screw hole 22c having a diameter larger than that of the valve insertion hole 22a is formed, and a cylindrical set screw 25 screw-engaged with the screw hole 22c is formed. The relief valve 30 inserted into the valve insertion hole 22a may be fixed by tightening.
[0042]
【The invention's effect】
As described above, according to the present invention, the cap is press-fitted into the open end of the sleeve and the valve body and the spring incorporated in the sleeve are held in the assembled state, so that the relief valve can be assembled very easily. And cost can be reduced.
[0043]
In addition, by fixing the relief valve in the oil drainage passage, it is possible to prevent the relief valve from moving due to pressure fluctuations in the pressure chamber, to prevent the generation of vibration and noise, and the relief valve. It is possible to prevent the hydraulic oil in the pressure chamber from leaking from the oil discharge passage in the closed state, and it is possible to prevent the damper effect from being lowered.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view showing a first embodiment of a chain tensioner according to the present invention. FIG. 2 is a longitudinal front view showing a state before the relief valve of the chain tensioner shown in FIG. 1 is assembled. FIG. 4 is an enlarged cross-sectional view of the chain tensioner relief valve assembly shown in FIG. 4. FIG. 5 is an enlarged cross-sectional view of a part of the chain tensioner plunger shown in FIG. FIG. 6 is a longitudinal front view showing a second embodiment of the chain tensioner according to the present invention. FIG. 7 is an enlarged sectional view showing an assembly portion of the relief valve of the chain tensioner shown in FIG . 8] Cross-sectional view showing another example of means for fixing the relief valve [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 2 Cylinder chamber 3 Plunger 5 Spring 6 Pressure chamber 7 Oil supply passage 20 Oil discharge passage 20a Valve insertion hole 20b Screw hole 21 Step part 22 Oil discharge passage 22a Valve insertion hole 22b Retainer fitting hole 22c Screw hole 23 Hole retainer 24 Step 25 Set screw
30 relief valve
31 sleeves
32 caps
33 Valve body
34 disc
35 spring
36 valve holes
37 discharge hole 43 rod

Claims (6)

A plunger that is slidable in a cylinder chamber formed in the housing and a spring that presses the plunger outward are incorporated, and the housing is provided with an oil supply passage that communicates with a pressure chamber formed on the back of the plunger, In a chain tensioner that incorporates a relief valve that opens and discharges hydraulic fluid in the pressure chamber when the pressure of the hydraulic fluid in the pressure chamber exceeds the set pressure in the drainage passage that communicates with the outside of the pressure chamber. Has a valve body composed of a sleeve having a press-molded end plate and a cap press-fitted into the open end of the sleeve, and communicates with the cap of the valve body on the oil inlet side of the oil discharge passage. the valve hole is provided, said sleeve provided with a discharge hole communicating with the oil outlet of the oil discharge passage, a valve body for the valve hole opened and closed in the valve in the body, Become the valve body from incorporating the assembly and a spring for pressing in the closing direction, the chain tensioner, characterized in that fixed the relief valve to drain oil passage formed stepped valve insertion hole.   The chain tensioner according to claim 1, wherein the relief valve is provided with limiting means for limiting an opening / closing amount of the valve body.   The chain tensioner according to claim 2, wherein the restricting means is a rod integrally provided on the cap.   3. The chain tensioner according to claim 2, wherein the restricting means comprises a rod incorporated in the valve body. As a means for fixing the relief valve, a screw hole having a diameter larger than that of the valve insertion hole is provided on the valve insertion side of the valve insertion hole formed in the oil discharge passage, and a set screw is engaged with the screw hole. The chain tensioner according to any one of claims 1 to 4, wherein the chain tensioner is configured to press the relief valve against a step portion of the valve insertion hole . The means for fixing the relief valve is provided with a retainer fitting hole on the valve insertion side of the valve insertion hole formed in the oil drainage passage, and a perforated retainer is press-fitted into the retainer fitting hole to form a step portion of the valve insertion hole. The chain tensioner according to any one of claims 1 to 4 , wherein a relief valve is pressed against the chain tensioner.

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