JP2002054701A - Hydraulic chain tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic chain tensioner capable of reducing machining cost. SOLUTION: A guide hole 4 and an oil feeding hole 5 opened at the bottom of the guide hole 4 are formed in the housing 1. A plunger 9 is slidably incorporated in the guide hole 4, and a return spring 12 and a check valve 13 are incorporated in a hydraulic damper chamber 11 formed at the back thereof. An orifice 18 penetrating from the upper part of the outer periphery of the housing 1 to the hydraulic damper chamber 11 is provided, so that when the plunger 9 retreats, an operating fluid in the hydraulic damper chamber 11 positively leaks from the orifice 18. The leakage amount and the amount of leak leaking from a leak gap 10 between the plunger 9 and the sliding part of the guide hole 4 are jointly managed so that the width of the leak gap corresponding to a suitable leak down time is increased so as to reduce machining cost by increase of machining tolerance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a hydraulic chain tensioner, a housing attached to a cylinder block is provided with a bottomed guide hole and an oil supply hole opened at the bottom of the guide hole, and a plunger is slidable in the guide hole. A return spring that presses the plunger outward in the hydraulic damper chamber and a check valve that prevents the hydraulic oil in the hydraulic damper chamber from flowing back to the oil supply hole side are installed. Have been known for some time.

[0003] The hydraulic chain tensioner presses the chain by a plunger provided with an outward projecting property by a return spring, and buffers the pushing force applied from the chain to the plunger with hydraulic oil in a hydraulic damper chamber. When the pushing force exceeds the pushing force of the return spring, the operating oil in the hydraulic damper chamber is leaked to the outside from the leak clearance formed between the sliding surface of the plunger and the guide hole, and the plunger is pushed with the pushing force. It is made to slowly retreat to a position where the pressing force of the return spring is balanced.

[0004] Here, the leak down time when the hydraulic oil in the hydraulic damper chamber leaks from the leak clearance to the outside is regarded as one of the important indices for determining the performance of the hydraulic chain tensioner. This leak down time depends on the speed of leakage of hydraulic oil in the hydraulic damper chamber. A longer one has high rigidity as a chain tensioner and can maintain the chain at high tension. If the length is longer than necessary, the chain will be over-tensioned and cause breakage, which is not preferable.

On the other hand, when the leak down time is short, the tension of the chain can be suppressed low. However, when the leak down time is too short, the displacement of the plunger becomes excessive, which causes abnormal noise.

Therefore, it is necessary to manage the leak down time within an appropriate range.

[0007]

By the way, when managing the leak down time of the hydraulic chain tensioner,
Conventionally, the size of the leak clearance formed between the sliding surface of the plunger and the guide hole and the length of the leak clearance are controlled. In this case, if the leak clearance is determined within an optimum range, the range of the leak clearance is limited to an extremely limited narrow width, and the processing tolerance when processing the inner diameter of the guide hole and the outer diameter of the plunger is reduced. For this reason, precision machining is required for machining these parts, and after machining, it is necessary to combine a housing and a plunger so as to obtain an optimum leak clearance, which disadvantageously increases machining costs. Was.

Generally, hydraulic oil supplied to a hydraulic damper chamber of a hydraulic auto tensioner contains about 10% of air. In the case of a hydraulic auto-tensioner, if the chain suddenly loosens when the engine is started, the plunger largely moves outward, and the movement reduces the pressure in the hydraulic damper chamber. Air enters.

If such air is mixed into the hydraulic oil in the hydraulic damper chamber, the function of the hydraulic damper is reduced, the displacement of the plunger increases, and abnormal noise is generated.

In order to eliminate such inconvenience, a relatively small-diameter air vent hole is provided at the tip of the plunger or at the cylinder for communicating the hydraulic damper chamber with the outside, and the air in the hydraulic damper chamber is vented from the air vent hole. I have to.

In a conventionally known hydraulic chain tensioner provided with an air vent hole at the tip of a plunger, a return spring for pressing the plunger outward is provided substantially at the inner periphery of a spring accommodating hole formed in the plunger. Due to the shape of the return spring, air easily accumulates in the inner diameter portion of the return spring, and there is a disadvantage that air cannot be discharged smoothly.

The present invention provides a hydraulic chain tensioner capable of increasing the width of a leak clearance corresponding to an appropriate leak down time and reducing machining costs by increasing machining tolerances. Is a first technical problem.

Another object of the present invention is to provide a hydraulic chain tensioner capable of smoothly discharging air mixed into hydraulic oil in a hydraulic damper chamber.

[0014]

In order to solve the above-mentioned first problem, according to the present invention, a housing having a bottomed guide hole and an oil supply hole opened at the bottom of the guide hole are formed. A plunger is slidably incorporated in the guide hole, a hydraulic damper chamber is provided at the back thereof, and a return spring for pressing the plunger outward in the hydraulic damper chamber, and hydraulic oil in the hydraulic damper chamber flows backward to the oil supply hole side. And a check valve for preventing the hydraulic oil from leaking out of the hydraulic damper chamber from the leak gap formed between the plunger and the sliding surface of the guide hole when the plunger is retracted. In the chain tensioner, an orifice for hydraulic oil leakage is provided in one of the housing and the plunger for communicating the hydraulic damper chamber with the outside. It has adopted the configuration.

As described above, by providing the orifice for communicating the hydraulic damper chamber with the outside, the hydraulic oil in the hydraulic damper chamber can be actively leaked from the orifice when the plunger is retracted. For this reason, by managing the amount of leakage and the amount of hydraulic oil leaking from the leakage clearance together, the width of the leakage clearance corresponding to an appropriate leakage down time is increased, and the guide hole that forms the leakage clearance The machining tolerance at the time of machining the inner diameter of the plunger and the outer diameter of the plunger is expanded, and the machining cost can be reduced.

Here, if the cross-sectional area of the orifice is small and the length is long, the hydraulic oil cannot flow out smoothly, and conversely, the cross-sectional area of the flow path is unnecessarily large, When the length is short, the hydraulic damper effect is reduced, so the size and length of the flow path cross-sectional area are appropriately determined according to the leak clearance and the viscosity of the working oil used.

In forming the orifice, a circular through hole communicating with the hydraulic damper chamber is formed in the housing or the plunger, and a spiral groove is formed on the inner periphery of the through hole.
By press-fitting the columnar plug into the through-hole, a long orifice having a small flow path cross-sectional area can be easily formed.

A spiral groove may be formed on the outer periphery of the plug, and the plug may be pressed into a through hole having the same inner diameter over the entire length in the axial direction.

In the hydraulic chain tensioner according to the present invention, a clip mounting groove is provided on the inner periphery of the opening of the guide hole, and a radially elastically deformable ring portion provided on the register clip is mounted in the clip mounting groove. A plurality of circumferential grooves which are fastened by a ring portion of the register clip are formed at intervals in an axial direction on an outer periphery of the plunger, and a ring portion of the register clip is formed on an outer periphery of each circumferential groove when the plunger advances. By providing a tapered surface for expanding the diameter of the chain and an engagement surface for engaging the ring portion of the register clip when the plunger is retracted to prevent the plunger from retreating, the cam stops when the engine is stopped. If the chain is strained and the plunger is pushed in by the chain, the plunger engages the register clip with the engaging surface of the circumferential groove Not be setback be only to retreat to the location. For this reason, even if the engine is restarted, the chain can be prevented from being slackened by an amount corresponding to the retreat amount of the plunger, so that the chain can be largely slackened, and an appropriate damping characteristic can always be obtained.

Further, in the chain tensioner according to the present invention, the plunger is engaged with the ring portion of the register clip at a position rearward of a rearmost one of the plurality of circumferential grooves arranged in the axial direction on the outer periphery of the plunger. If a stopper groove is provided to prevent the stopper from being pulled out, during maintenance around the engine where the chain is removed, the plunger moves outward by pressing the return spring, and when the plunger moves forward to the position where the stopper groove corresponds to the register clip, the The ring portion engages with the stopper groove to prevent the plunger from coming off. For this reason, it is possible to prevent parts such as the plunger and the return spring from being disassembled separately.

Further, in the chain tensioner according to the present invention, the plunger is pushed into the guide hole by abutting the ring portion of the register clip forward of the foremost circumferential groove of the circumferential grooves arranged in the axial direction of the plunger. By providing the stopper surface for holding the initial set state, it is not necessary to push the plunger when assembling the chain, so that the assembling can be facilitated.

In order to solve the second problem, according to the present invention, there is provided a spring accommodating hole for accommodating a return spring in the plunger of the hydraulic chain tensioner described above, and an orifice communicating from the tip to the spring accommodating hole. The end of the return spring that presses the plunger has a small diameter, and a gap is provided between the outer periphery of the tip of the return spring and the inner peripheral surface of the spring receiving hole.

With the above-described structure, the air mixed into the hydraulic oil easily accumulates in the gap formed between the outer periphery of the distal end portion of the return spring and the inner peripheral surface of the spring receiving hole.
The accumulated air is easily discharged to the outside together with the hydraulic oil flowing through the orifice.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of a hydraulic chain tensioner according to the present invention. A plurality of mounting pieces 2 are formed on the outer periphery of a housing 1 made of a casting or a light alloy such as an aluminum alloy, and each mounting piece 2 is provided with a bolt insertion hole 3.

The housing 1 has a guide hole 4 with a bottom, and an oil supply hole 5 opening at the bottom of the guide hole 4.
Are formed. Furthermore, the housing 1 is provided with a clip mounting groove 6 on the inner periphery of the open end of the guide hole 4 and a cutout 7 that opens across the clip mounting groove 6 at the distal end surface of the housing 1.

A register clip 8 is mounted in the clip mounting groove 6. As shown in FIG. 3, the register clip 8 is provided with a pair of operation pieces 8b at both ends of a ring portion 8a that can be elastically deformed in the radial direction, and the ring portion 8a is fitted into the clip mounting groove 6 to form a pair of operation members. The piece 8b is inserted into the notch 7. The distal end portion of the operation piece 8b faces the outside, and the diameter of the ring portion 8a is increased by pinching the pair of operation pieces 8b.

As shown in FIGS. 1 and 2, the guide hole 4
A plunger 9 is slidably incorporated therein, and a leak clearance 10 is provided between the plunger 9 and the sliding surface of the guide hole 4. A hydraulic damper chamber 11 is provided on the back of the plunger 9 by assembling the plunger 9. A return spring 12 and a check valve 13 are incorporated in the hydraulic damper chamber 11. The return spring 12 is accommodated in an axial spring accommodation hole 14 opened at the rear end face of the plunger 9, and presses a closed end thereof. And
The pressing gives the plunger 9 an outward protruding property.

On the outer periphery of the plunger 9, a plurality of circumferential grooves 15 elastically fastened by the ring portion 8a of the register clip 8 are formed at equal intervals in the axial direction. A stopper surface 16 is provided on the outer periphery of the plunger 9 in front of the foremost circumferential groove 15 of the circumferential grooves 15 arranged in the axial direction, and a stopper groove 17 is provided on the rear side of the rearmost circumferential groove 15. ing.

The plunger 9 includes a register clip 8
By the engagement of the stopper surface 16 with the ring portion 8a, the initial set state pushed into the guide hole 4 is maintained. Further, the plunger 9 is prevented from coming off by engagement of the side surface 17a on the trailing side of the stopper groove 17 when the plunger advances, and the ring portion 8a of the register clip 8.

As shown in FIG. 4, on the outer periphery of each of the plurality of circumferential grooves 15 formed in the plunger 9, an engaging surface 15a is provided on the leading side when the plunger 9 moves forward in the outward direction.
A tapered surface 15b is formed on the trailing side, and the engagement surface 15b is formed.
When the plunger 9 retreats, it engages with the ring portion 8a of the register clip 8 to prevent the plunger 9 from retreating. On the other hand, the tapered surface 15b is
The diameter of the ring portion 8a is expanded when moving forward.

As shown in FIGS. 1 and 2, the check valve 13 has a valve seat 13a and its valve seat 1a.
It comprises a valve body 13c for opening and closing a valve hole 13b formed in 3a from the hydraulic damper chamber 11 side, and a retainer 13d for limiting the opening and closing amount of the valve body 13c. This check valve 1
3 prevents the hydraulic oil in the hydraulic damper chamber 11 from flowing back to the oil supply hole 5 side.

As shown in FIG. 1, the housing 1 is provided with a hydraulic damper chamber 11 from the upper surface of the outer periphery in the mounted state.
An orifice 18 is provided toward the end. In forming the orifice 18, here, a circular through hole 19 is formed in the housing 1 from the upper surface toward the hydraulic damper chamber 11,
The orifice 18 formed of a spiral groove on the inner periphery of the through hole 19
And a columnar plug 20 is pressed into the through hole 19. A spiral groove may be formed on the outer periphery of the plug 20, and the plug 20 may be pressed into a through hole having the same diameter over the entire length in the axial direction to form a spiral orifice.

The orifice 18 has a cross-sectional area through which the hydraulic oil in the hydraulic damper chamber 11 can leak to the outside. The leak clearance 10 is determined to have an appropriate size. That is, by managing the amount of hydraulic oil leaked from the orifice 18 and the amount of hydraulic oil leaked from the leak clearance 10 together, the leak clearance 10 is determined from the relationship with the orifice 18 so that an appropriate leak down time can be obtained. Is determined to be an appropriate size.

The hydraulic chain tensioner shown in the embodiment has the above-mentioned structure, and when adjusting the tension of the camshaft driving chain, the housing 1 is fixed to the cylinder block by tightening bolts inserted into the bolt insertion holes 3. . In this case, as shown in FIG. 1, it is preferable that the plunger 9 is attached so that the plunger 9 is slightly inclined with a downward slope toward the tip.

When the housing 1 is mounted, the ring portion 8a of the register clip 8 is engaged with the stopper surface 16 of the plunger 9 to hold the plunger 9 in a pushed-in state. The operation piece 8b is pinched, the diameter of the ring portion 8a is expanded, and the engagement with the stopper surface 16 is released.
The plunger 9 is protruded outward by the pressing, and the swingable chain guide (not shown) is pressed by the plunger 9 to apply tension to the chain.

When the engine is driven while the tension of the chain is adjusted as described above, the intake / exhaust valve is opened by the rotation of the camshaft, and a fluctuating load is applied to the chain in accordance with the opening and closing of the valve. It vibrates with it. Therefore, the chain repeats tension and relaxation, and a pushing force is applied to the plunger 9 when the chain is tensioned. At this time, since the pressure in the hydraulic damper chamber 11 increases, the check valve 13 is closed, and the hydraulic damper chamber 11 is closed.
The pushing force is buffered by the hydraulic oil sealed in the inside. The minimum value of the pushing force is return spring 1
In the case of a large pushing force exceeding the combined force of the elasticity 2 and the operating oil pressure, the plunger 9 moves backward to a position where the combined force and the pushing force are balanced.

At this time, the ring portion 8a of the register clip 8 moves in the clip mounting groove 6, and does not prevent the plunger 9 from retreating. The hydraulic oil in the hydraulic damper chamber 11 leaks outside through the leak gap 10 and the orifice 18 formed between the guide hole 4 and the sliding surface of the plunger 9. The air mixed in the hydraulic oil in the hydraulic damper chamber 11 is discharged to the outside together with the hydraulic oil flowing out of the orifice 18.

On the other hand, when the chain becomes slack, the plunger 9 moves forward by the pressing of the return spring 12 to absorb the slack of the chain and keep the tension of the chain constant.

When the chain is stretched due to wear,
The plunger 9 moves forward by the pressing of the return spring 12 to absorb the elongation of the chain. At this time, if the elongation of the chain is greater than the pitch of the circumferential groove 15, the ring portion 8a of the register clip 8 fits into the next circumferential groove 15 and elastically contacts the outer periphery of the circumferential groove 15. .

When the engine is stopped, the plunger 9 may be pushed in due to the stop position of the cam. Further, when the change lever is engaged in the forward gear on an uphill slope, or when the downshift is stopped with the change gear engaged in the reverse gear, the chain is tensed and the plunger 9 is pushed in.

At this time, the plunger 7 is retracted, and the engaging surface 15a of the circumferential groove 15 is
a and the stopper surface 6 of the clip mounting groove 6
a, and the plunger 7 stops.

For this reason, the chain is only slackened by an amount corresponding to the retreat amount of the plunger 7, but is not greatly slackened. Therefore, even if the engine is restarted, the chain does not loosen significantly, and it is possible to prevent the chain from being detached from the sprocket or the tooth from jumping.

In the hydraulic chain tensioner as described above, the operating oil leaks from both the leak clearance 10 formed between the plunger 9 and the sliding surface of the guide hole 4 and the orifice 18, so that the leak is reduced. Compared with the case where the hydraulic oil leaks only from the clearance, the width of the leakage clearance corresponding to an appropriate leak down time can be increased. To prove this, a hydraulic chain tensioner that leaks hydraulic oil only from the leak clearance and an orifice (0.2 m inside diameter) for air release
m) and the relationship between leak clearance and leak down time using three hydraulic auto-tensioners, a hydraulic chain tensioner with a hydraulic oil tension orifice (0.4 mm inner diameter) and a hydraulic chain tensioner with an orifice (inner diameter 0.4 mm) Was obtained, the result shown in FIG. 5 was obtained.

In the test, a hydraulic oil having a kinematic viscosity of 70 mm ² / sec at 20 ° C.
A load of 00N was applied.

In the above graph, if the width of the appropriate leak down time is in the range of AB on the vertical axis, 0.4φ
In a hydraulic auto tensioner with an orifice for leaking hydraulic oil, the appropriate leak clearance width is ab
Range.

On the other hand, a hydraulic chain tensioner configured to leak hydraulic oil only from the leak clearance, and a hydraulic chain tensioner having a hydraulic chain tensioner.
In a hydraulic chain tensioner with a 2φ air bleeding orifice, the appropriate leak clearance width is a '
−b ′.

As described above, the orifice 1 for hydraulic oil leakage
Forming the groove 8 increases the width of the leak clearance corresponding to an appropriate leak down time, and accordingly increases the processing tolerance when processing the inner diameter of the guide hole 4 and the outer diameter of the plunger 9, thereby processing each surface. Therefore, processing with high dimensional accuracy is not required, and the processing cost can be reduced.

FIG. 6 shows a second embodiment of the hydraulic chain tensioner according to the present invention. The hydraulic chain tensioner shown in this embodiment is different from the hydraulic chain tensioner of the first embodiment shown in FIG. 1 in the formation position of the orifice for leaking hydraulic oil.

That is, in the second embodiment, a through hole 21 is formed in the plunger 9 from the distal end surface to the spring accommodating hole 14, and an orifice 22 formed of a spiral groove is formed on the inner periphery of the through hole 21. The plug 2 is inserted into the through hole 21.
3 is press-fitted.

An orifice formed of a spiral groove may be formed on the outer periphery of the plug 23, and the plug 23 may be press-fitted into a through-hole having the same diameter throughout the axial direction.

In the hydraulic chain tensioner having the above configuration, the housing 1 is mounted on the cylinder block so that the plunger 9 is inclined with a slight upward slope toward the tip, and is used when the plunger 9 is pushed in. The hydraulic oil in the damper chamber 11 is leaked outside from both the leak gap 10 formed between the guide hole 4 and the sliding surface of the plunger 9 and the orifice 22.

Also in the second embodiment, similarly to the first embodiment, the width of the leak clearance 10 for an appropriate leak down time can be increased, and the processing cost can be reduced by increasing the processing tolerance. Can be achieved.

FIGS. 7 and 8 show a third embodiment of the hydraulic chain tensioner according to the present invention. In the hydraulic chain tensioner shown in this embodiment,
A through-hole 24 is formed in the plunger 9 from the distal end surface to penetrate the spring accommodating hole 14, and an orifice 26 formed of a spiral groove is formed on the outer periphery of the plug 25 pressed into the through-hole 24. A spring seat 27 for receiving the end of the return spring 12 is provided on the plug 25, and a plurality of grooves 28 penetrating with the orifice 26 are formed radially on the surface of the spring seat 27 where the plug 25 is provided. I have.

Since the other structure is the same as that of the hydraulic chain tensioner shown in FIG. 6, the same components are denoted by the same reference numerals and description thereof is omitted.

As described above, the spring seat 27 is provided integrally with the plug 25, and the spring seat 27 is engaged with the closed end of the spring accommodating hole 14, so that the plug 25 is reliably prevented from falling off. be able to.

When the plunger 9 is pushed in,
Since hydraulic oil can be leaked from both the leak gap 10 and the orifice 26, the width of the leak gap 10 for an appropriate leak down time can be increased, and the machining tolerance can be increased, thereby reducing the machining cost.

FIG. 9 shows a fourth embodiment of the hydraulic chain tensioner according to the present invention. This embodiment and FIG.
Only the shape of the return spring 12 is different from the hydraulic chain tensioner shown in FIG. That is, in this embodiment, the return spring 12 has a tapered shape, and the tip for pressing the plunger 9 has a small diameter.

As described above, if the return spring 12 is tapered, a wedge-shaped gap 29 can be formed between the distal end of the return spring 12 and the inner periphery of the spring receiving hole 14, so that the return oil 12 is mixed with the hydraulic oil. The generated air easily accumulates in the gap 29, and the air mixed into the hydraulic oil can be smoothly discharged to the outside from the orifice 26 together with the hydraulic oil, so that the reduction of the hydraulic damper effect can be suppressed.

In the fourth embodiment, the return spring 12 has a tapered shape, and a wedge-shaped gap 29 is formed between the distal end of the return spring 12 and the inner periphery of the spring accommodating hole 14. The coil portion and the small-diameter coil portion may be formed, and a cylindrical gap may be formed between the outer periphery of the small-diameter coil portion and the inner periphery of the spring receiving hole 14.

FIGS. 10 (I) and (II) show a hydraulic chain tensioner according to a fifth embodiment of the present invention.
In the fifth embodiment, a mounting piece 30 having a bolt insertion hole 31 is formed in a housing 1 and a positioning pin 3 is provided on an abutting surface of the housing 1 against a cylinder block.
2, and the positioning pins 32 are inserted into positioning holes formed in the cylinder block.
The housing 1 is mounted on the cylinder block by tightening bolts inserted into the cylinder block.

As described above, the provision of the positioning pins 32 facilitates the mounting of the housing 1 as compared with the case where the two mounting pieces 2 are mounted on the cylinder block by tightening bolts as shown in FIG. Can be planned.

FIG. 11 shows a sixth embodiment of the hydraulic chain tensioner according to the present invention. In this embodiment, a hollow pin 3 is provided in an oil supply hole 5 formed in the housing 1.
3 is press-fitted, the hollow pin 33 is press-fitted into an oil outlet of an oil supply passage formed in the cylinder block to position the housing 1, and a bolt is inserted into a bolt insertion hole 35 of a mounting piece 34 provided in the housing 1. And the housing 1 is fixed by tightening the bolts.

As described above, since the oil supply passage formed in the cylinder block can be used as a positioning hole by press-fitting the hollow pin 33 into the oil supply hole 5, it is necessary to separately process the positioning hole in the cylinder block. And the processing can be facilitated.

[0064]

As described above, according to the present invention, when the plunger is retracted, the hydraulic oil in the hydraulic damper chamber is leaked from both the orifice and the leak clearance, so that the leak clearance corresponding to an appropriate leak down time is provided. The processing tolerance when processing the inner diameter of the guide hole and the outer diameter of the plunger is increased by that amount, and processing with high dimensional accuracy is not required for processing of each surface, reducing the processing cost. Can be planned.

Also, the tip of the return spring for suppressing the plunger has a small diameter, and a gap is formed between the tip of the return spring and the inner periphery of the spring receiving hole formed in the plunger. The air easily accumulates, and the air can smoothly flow out to the outside together with the hydraulic oil from the orifice formed at the tip of the plunger.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

4 is an enlarged sectional view showing a part of a plunger of the hydraulic chain tensioner shown in FIG. 1;

FIG. 5 is a graph showing a relationship between a leak gap of a hydraulic chain tensioner and a leak down time.

FIG. 6 is a longitudinal sectional front view showing a second embodiment of the hydraulic chain tensioner according to the present invention;

FIG. 7 is a sectional view showing a third embodiment of the hydraulic chain tensioner according to the present invention;

8 is a transverse sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is a longitudinal sectional front view showing a fourth embodiment of the hydraulic chain tensioner according to the present invention;

FIG. 10 (I) is a front view showing a fifth embodiment of a hydraulic chain tensioner according to the present invention, and FIG. 10 (II) is a partially cutaway plan view.

FIG. 11 is a partially cutaway plan view showing a sixth embodiment of the hydraulic chain tensioner according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 4 Guide hole 5 Oil supply hole 6 Clip mounting groove 8 Register clip 8a Ring part 9 Plunger 10 Leak clearance 11 Hydraulic damper chamber 12 Return spring 13 Check valve 14 Spring accommodation hole 15 Circular groove 15a Engagement surface 15b Taper surface 16 Stopper Surface 17 Stopper groove 18 Orifice 19 Through hole 20 Plug 21 Through hole 22 Orifice 23 Plug 24 Through hole 25 Plug 26 Orifice 27 Spring seat 28 Groove 29 Gap

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Niwa 1578 Higashikaizuka, Iwata-shi, Shizuoka F-term (reference) 3N049 AA08 BB13 BB26 BB33 BB35 BC03 CA02

Claims (8)

[Claims] 1. A housing having a bottomed guide hole and an oil supply hole opened at the bottom of the guide hole. A plunger is slidably incorporated in the guide hole, and a hydraulic damper chamber is provided at the back of the plunger. A return spring that presses the plunger outward in the hydraulic damper chamber and a check valve that prevents hydraulic oil in the hydraulic damper chamber from flowing back to the oil supply hole side are incorporated. In a hydraulic chain tensioner in which hydraulic oil is leaked outside from a leak gap formed between a sliding surface of a plunger and a guide hole, a hydraulic damper chamber and an outside are provided in one of the housing and the plunger. A hydraulic chain tensioner having an orifice for a hydraulic oil leak to be communicated. 2. A clip mounting groove is provided on an inner periphery of an opening of the guide hole, and a radially elastically deformable ring portion provided on a register clip is mounted in the clip mounting groove. A plurality of circumferential grooves fastened by the ring portion of the register clip are formed at intervals in the axial direction, and on the outer periphery of each circumferential groove, a tapered surface for expanding the diameter of the ring portion of the register clip when the plunger advances, 2. The hydraulic chain tensioner according to claim 1, further comprising: an engagement surface which engages with a ring portion of the register clip when the plunger is retracted to prevent the plunger from retreating. 3. A stopper groove for preventing the plunger from coming off by engagement with a ring portion of a register clip is provided on a rear side of a rearmost circumferential groove of a plurality of circumferential grooves arranged in the axial direction on an outer periphery of the plunger. The hydraulic chain tensioner according to claim 2. 4. The plunger is held in an initial set state in which the plunger is pushed into the guide hole by abutting the ring portion of the register clip on a front side of a foremost circumferential groove of the circumferential grooves arranged in the axial direction of the plunger. The hydraulic chain tensioner according to claim 3, further comprising a stopper surface. 5. A circular through-hole penetrating from the upper part of the outer periphery of the housing to the hydraulic damper chamber, and a plug is pressed into the through-hole, and a spiral groove is formed on one of the outer periphery of the stopper and the inner periphery of the through-hole. 5. The hydraulic chain tensioner according to claim 1, further comprising an orifice formed of: 6. A spring accommodating hole for accommodating a return spring in the plunger, and a circular through hole communicating from the tip end surface to the spring accommodating hole, and a shaft-like plug is pressed into the through hole. The hydraulic chain tensioner according to any one of claims 1 to 4, wherein an orifice formed of a spiral groove is provided on one of an outer peripheral surface of the plug and an inner peripheral surface of the through hole. 7. The spring body according to claim 6, wherein a spring seat for receiving an end of the return spring is provided integrally with the plug body, and a radial groove communicating with an orifice is provided on a surface of the spring seat where the plug body is provided. The described hydraulic chain tensioner. 8. The hydraulic chain tensioner according to claim 6, wherein an end of the return spring that presses the plunger has a small diameter.