JP4072306B2 - Hydraulic chain tensioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic chain tensioner that maintains a constant tension of a camshaft drive chain.
[0002]
[Prior art]
As a hydraulic chain tensioner, a guide hole with a bottom is formed in a housing attached to a cylinder block, and an oil supply hole that opens at the bottom of the guide hole is formed. A plunger is slidably incorporated in the guide hole and its back part is formed. Conventionally, a hydraulic damper chamber is provided in the hydraulic damper chamber, and 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 have been incorporated. Are known.
[0003]
The hydraulic chain tensioner presses the chain with a plunger to which outward protrusion is imparted by a return spring, and the pushing force applied from the chain to the plunger is buffered by the hydraulic oil in the hydraulic damper chamber. When the force exceeds the pressing force of the return spring, hydraulic 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 in and the return spring Slowly retracts to a position where the pressing force 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 one of the important indexes that determine 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 long 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.
[0005]
On the other hand, if the leak down time is short, the chain tension can be kept low, but if the leak down time is too short, the displacement of the plunger becomes excessive, which may cause abnormal noise.
[0006]
Therefore, it is necessary to manage the leak down time within an appropriate range.
[0007]
[Problems to be solved by the invention]
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 surfaces of the plunger and the guide hole and the length of the leak clearance are controlled. In this case, when the leak clearance is determined within the optimum range, the range of the leak clearance is limited to a very 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, the machining of these parts requires precise machining, and it is necessary to combine the housing and the plunger so as to obtain an optimum leak clearance after machining, resulting in high machining costs. It was.
[0008]
Generally, hydraulic oil supplied to a hydraulic damper chamber of a hydraulic auto tensioner contains about 10% air. Also, in the hydraulic auto tensioner, if the chain is suddenly loosened when the engine is started, the plunger moves greatly in the outward direction, and the movement reduces the pressure in the hydraulic damper chamber. Air enters.
[0009]
When such air is mixed in the hydraulic oil in the hydraulic damper chamber, the hydraulic damper function is deteriorated, and the displacement of the plunger increases to generate noise.
[0010]
In order to eliminate such inconvenience, a relatively small-diameter air vent hole that communicates the hydraulic damper chamber with the outside is provided in the tip of the plunger or the cylinder, and the air in the hydraulic damper chamber is extracted from the air vent hole. .
[0011]
Further, in a conventionally known hydraulic chain tensioner provided with an air vent hole at the tip of the plunger, a return spring that presses the plunger outward is formed substantially along the inner circumference of the spring accommodation hole formed in the plunger. Therefore, there is a problem that air tends to accumulate in the inner diameter portion of the return spring, and the air cannot be discharged smoothly.
[0012]
The present invention provides a hydraulic chain tensioner capable of expanding the leak clearance corresponding to an appropriate leak down time and reducing the processing cost by increasing the processing tolerance. This is the first technical problem.
[0013]
In addition, a second technical problem of the present invention is to provide a hydraulic chain tensioner that can smoothly discharge air mixed in hydraulic oil in a hydraulic damper chamber.
[0014]
[Means for Solving the Problems]
In order to solve the first problem, in the present invention, a bottomed guide hole and an oil supply hole opened at the bottom of the guide hole are formed in the housing, and a plunger is slid into the guide hole. A hydraulic damper chamber is provided at the back of the hydraulic damper chamber, a return spring that presses the plunger outwardly in the hydraulic damper chamber, and a check valve that prevents the hydraulic oil in the hydraulic damper chamber from flowing backward to the oil supply hole side. In the hydraulic chain tensioner, the hydraulic fluid 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 when the plunger is retracted. One of these is provided with an orifice for hydraulic fluid leakage that connects the hydraulic damper chamber to the outside A clip mounting groove is provided in the inner periphery of the opening of the guide hole, and a radially elastically deformable ring portion provided in the register clip is mounted in the clip mounting groove. A plurality of circumferential grooves that are tightened by the ring portion are formed at intervals in the axial direction, and a tapered surface that expands the diameter of the ring portion of the register clip when the plunger is advanced on the outer periphery of each circumferential groove, and when the plunger is retracted An engagement surface that engages with the ring portion of the register clip to prevent the plunger from moving backward, and the register clip ring is positioned in front of the most circumferential groove in the circumferential groove aligned in the axial direction of the plunger. A stopper surface is provided to hold the plunger in the initial set state by pushing it into the guide hole by contact Adopted.
[0015]
As described above, by providing the orifice that communicates 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. Therefore, by managing the leak amount and the leak amount of hydraulic oil leaking from the leak clearance together, the width of the leak clearance corresponding to the appropriate leak down time is widened, and the guide hole that forms the leak clearance The machining tolerance at the time of machining the inner diameter and the outer diameter of the plunger is enlarged, and the machining cost can be reduced.
[0016]
Here, if the orifice cross-sectional area is small and the length is long, the hydraulic oil cannot flow smoothly, and conversely, the cross-sectional area is larger than necessary and the length is short. Since the hydraulic damper effect is reduced, the size and length of the flow path cross-sectional area are appropriately determined according to the leak clearance and the viscosity of the hydraulic fluid used.
[0017]
When forming the orifice, a circular through hole communicating with the hydraulic damper chamber is formed in the housing or plunger, a spiral groove is formed in the inner periphery of the through hole, and a columnar plug is press-fitted into the through hole. A long orifice with a small flow path cross-sectional area can be easily formed.
[0018]
In addition, a spiral groove may be formed on the outer periphery of the plug body, and the plug body may be press-fitted into a through hole having the same inner diameter over the entire length in the axial direction.
[0019]
In the hydraulic chain tensioner according to the present invention, a clip mounting groove is provided in the inner periphery of the opening of the guide hole, and a radial elastically deformable ring portion provided in the register clip is mounted in the clip mounting groove, A plurality of circumferential grooves that are tightened by the ring portion of the register clip are formed on the outer periphery of the plunger at intervals in the axial direction, and the ring portion of the register clip is expanded on the outer periphery of each circumferential groove when the plunger is advanced. By providing the taper surface to be engaged and the engagement surface that engages the ring portion of the register clip and prevents the plunger from moving backward when the plunger is retracted, the chain is tensioned by the stop position of the cam when the engine is stopped. Even if the plunger is pushed in by the chain, the plunger moves back to the position where the engagement surface of the circumferential groove engages the register clip. It will not be setback be only that. For this reason, even when the engine is restarted, the chain can be prevented from being slackened by an amount corresponding to the retreating amount of the plunger, so that the chain can be prevented from slackening, and an appropriate damping characteristic can always be obtained.
[0020]
Further, in the chain tensioner according to the present invention, the plunger is prevented from coming off by engagement with the ring portion of the register clip at the rear end side from the circumferential groove at the rearmost end of the plurality of circumferential grooves arranged in the axial direction on the outer periphery of the plunger. If the stopper groove is provided, during maintenance around the engine to remove the chain, the plunger moves outward by pressing the return spring, and when the plunger advances to the position where the stopper groove corresponds to the register clip, the ring portion of the register clip Engage 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 apart.
[0021]
Furthermore, in the chain tensioner according to the present invention, an initial set in which the plunger is pushed into the guide hole by abutting against the ring portion of the register clip in front of the most peripheral circumferential groove arranged in the axial direction of the plunger. By providing the stopper surface to be held in the state, it is not necessary to push the plunger when assembling the chain, so that the assembling can be facilitated.
[0022]
In order to solve the second problem, in the present invention, a spring accommodation hole for accommodating a return spring in the plunger of the hydraulic chain tensioner described above, and an orifice communicating with the spring accommodation hole from the tip are provided. The end of the return spring on the side 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 accommodating hole.
[0023]
With the configuration described above, the air mixed in the hydraulic oil easily accumulates in the gap formed between the outer periphery of the tip end portion of the return spring and the inner peripheral surface of the spring accommodation hole, and the accumulated air flows to the orifice. At the same time, it becomes easy to be discharged to the outside.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
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 the housing 1 made of a light alloy such as a casting or an aluminum alloy, and a bolt insertion hole 3 is provided in each mounting piece 2.
[0025]
Further, the housing 1 is formed with a bottomed guide hole 4 and an oil supply hole 5 opened at the bottom surface of the guide hole 4. Furthermore, the housing 1 is provided with a clip mounting groove 6 on the inner periphery of the opening end portion of the guide hole 4 and a notch portion 7 that opens across the clip mounting groove 6 at the front end surface of the housing 1.
[0026]
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 so that a pair of operations is performed. The piece 8b is inserted into the notch 7. The tip of the operation piece 8b faces the outside, and the ring portion 8a is expanded in diameter by picking the pair of operation pieces 8b.
[0027]
As shown in FIGS. 1 and 2, a plunger 9 is slidably incorporated in the guide hole 4, and a leak gap 10 is provided between the sliding surface of the plunger 9 and the guide hole 4. In addition, a hydraulic damper chamber 11 is provided on the back of the plunger 9 by assembling. A return spring 12 and a check valve 13 are incorporated in the hydraulic damper chamber 11, and the return spring 12 is accommodated in an axial spring accommodating hole 14 that opens at the rear end surface of the plunger 9, and presses the closed end thereof. The plunger 9 is given an outward projecting property by the pressing.
[0028]
A plurality of circumferential grooves 15 that are elastically tightened by the ring portion 8a of the register clip 8 are formed on the outer periphery of the plunger 9 at equal intervals in the axial direction. Further, on the outer periphery of the plunger 9, a stopper surface 16 is provided on the front side of the most peripheral circumferential groove 15 of the circumferential groove 15 aligned in the axial direction, and a stopper groove 17 is provided on the rear side of the circumferential groove 15 at the rearmost end. ing.
[0029]
The plunger 9 is held in an initial set state in which the plunger 9 is pushed into the guide hole 4 by the engagement of the stopper surface 16 with the ring portion 8 a of the register clip 8. Further, the plunger 9 is prevented from coming off by the engagement of the side surface 17 a on the trailing side and the ring portion 8 a of the register clip 8 when the stopper groove 17 is advanced.
[0030]
As shown in FIG. 4, on the outer periphery of each of the plurality of circumferential grooves 15 formed on the plunger 9, there are an engagement surface 15a on the leading side when the plunger 9 moves forward outward, and a taper on the trailing side. The engaging surface 15a is engaged with the ring portion 8a of the register clip 8 when the plunger 9 is retracted to prevent the plunger 9 from retreating. On the other hand, the tapered surface 15b expands the diameter of the ring portion 8a when the plunger 9 moves forward.
[0031]
As shown in FIGS. 1 and 2, the check valve 13 includes a valve seat 13a, a valve body 13c that opens and closes a valve hole 13b formed in the valve seat 13a from the hydraulic damper chamber 11, and the opening and closing of the valve body 13c. And a retainer 13d for limiting the amount. The check valve 13 prevents the hydraulic oil in the hydraulic damper chamber 11 from flowing back to the oil supply hole 5 side.
[0032]
As shown in FIG. 1, the housing 1 is provided with an orifice 18 from the upper surface of the outer periphery in the attached state toward the hydraulic damper chamber 11. Here, when forming the orifice 18, a circular through hole 19 is formed in the housing 1 from the upper surface toward the hydraulic damper chamber 11, and an orifice 18 formed of a spiral groove is provided on the inner periphery of the through hole 19. A columnar stopper 20 is press-fitted into 19. Alternatively, a spiral groove may be formed on the outer periphery of the plug body 20, and the plug body 20 may be press-fitted into a through hole having the same diameter over the entire length in the axial direction to form a spiral orifice.
[0033]
The orifice 18 has a cross-sectional area through which hydraulic oil in the hydraulic damper chamber 11 can leak to the outside, and the leak clearance 10 is determined based on the relationship between the size and length of the cross-sectional area of the orifice 18 and the hydraulic oil used. Is determined to 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 gap 10 together, the leak gap 10 is determined from the relationship with the orifice 18 so that an appropriate leak down time can be obtained. Is determined to an appropriate size.
[0034]
The hydraulic chain tensioner shown in the embodiment has the above structure, and when adjusting the tension of the camshaft drive chain, the housing 1 is fixed to the cylinder block by tightening the bolt inserted into the bolt insertion hole 3. In this case, as shown in FIG. 1, it is preferable that the plunger 9 is attached so as to be slightly inclined with a downward slope toward the tip.
[0035]
When the housing 1 is attached, 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 the pushed state. After the housing 1 is fixed, the operation piece of the register clip 8 is operated. 8b is picked, the ring portion 8a is expanded to release the engagement with the stopper surface 16, the plunger 9 is protruded outward by pressing of the return spring 12, and the swingable chain guide not shown by the plunger 9 is shown. To apply tension to the chain.
[0036]
When the engine is driven with the chain tension adjusted as described above, the intake and exhaust valves are opened by the rotation of the camshaft, and a variable load is applied to the chain as it opens and closes, causing the chain to vibrate at a relatively high frequency. To do. For this reason, 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 becomes high, the check valve 13 is closed and the pushing force is buffered by the hydraulic oil sealed in the hydraulic damper chamber 11. In the case where the minimum value of the pushing force is a large pushing force that exceeds the resultant force of the return spring 12 and the hydraulic pressure, the plunger 9 moves backward to a position where the resultant force and the pushing force are balanced.
[0037]
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 moving backward. Further, the hydraulic oil in the hydraulic damper chamber 11 leaks to the outside from the leak gap 10 and the orifice 18 formed between the sliding surfaces of the guide hole 4 and the plunger 9. Further, 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 from the orifice 18.
[0038]
On the other hand, if slack occurs in the chain, the plunger 9 moves forward due to the pressing of the return spring 12, absorbs the slack in the chain, and keeps the chain tension constant.
[0039]
When the chain is stretched due to wear, the plunger 9 moves forward by the return spring 12 and absorbs the chain stretch. At this time, if the amount of chain extension is larger than the formation pitch of the circumferential groove 15, the ring portion 8 a of the register clip 8 fits into the next circumferential groove 15 and elastically contacts the outer periphery of the circumferential groove 15. .
[0040]
When the engine is stopped, the plunger 9 may be pushed in due to the cam stop position. On the uphill slope, when the change lever is in the forward gear, or when it is stopped with the back gear on the downhill, the chain 9 is tensioned and the plunger 9 is pushed.
[0041]
At this time, the plunger 7 moves backward, the engagement surface 15a of the circumferential groove 15 engages with the ring portion 8a of the register clip 8, and further contacts the stopper surface 6a of the clip mounting groove 6, and the plunger 7 stops. .
[0042]
For this reason, the chain is only slackened by an amount corresponding to the retraction amount of the plunger 7, and is not greatly slackened. Therefore, even if the engine is restarted, the chain does not loosen greatly, and it is possible to prevent the chain from coming off from the sprocket or causing tooth skipping.
[0043]
In the hydraulic chain tensioner as described above, the hydraulic fluid is leaked from both the leak gap 10 and the orifice 18 formed between the sliding surfaces of the plunger 9 and the guide hole 4, and therefore, only from the leak gap. Compared with the case of leaking hydraulic oil, the width of the leak clearance corresponding to an appropriate leak down time can be expanded. To prove this, a hydraulic chain tensioner that leaks hydraulic oil only from the leak clearance, a hydraulic chain tensioner with an air vent orifice (inner diameter 0.2 mm), and an hydraulic oil leak orifice ( When the relationship between the leak clearance and the leak down time was examined using three hydraulic auto tensioners of the hydraulic chain tensioner having an inner diameter of 0.4 mm, the result shown in FIG. 5 was obtained.
[0044]
During the test, the kinematic viscosity at 20 ° C. is 70 mm. ² A load of 100 N was applied to the plunger 9 using hydraulic fluid of / sec.
[0045]
In the above graph, assuming that the appropriate leak down time width is in the range AB on the vertical axis, the appropriate leak clearance width in a hydraulic auto tensioner with a 0.4φ hydraulic oil leakage orifice Is in the range ab.
[0046]
On the other hand, in the hydraulic chain tensioner in which the hydraulic oil is leaked only from the leak clearance and the hydraulic chain tensioner having the 0.2φ air vent orifice, the appropriate leak clearance width is in the range of a′−b ′. It becomes.
[0047]
As described above, when the orifice 18 for leaking hydraulic oil is formed, the width of the leak clearance corresponding to an appropriate leak down time is widened, and accordingly, when processing the inner diameter of the guide hole 4 and the outer diameter of the flanger 9. Machining tolerances are widened, machining with high dimensional accuracy is not required for machining each surface, and machining costs can be reduced.
[0048]
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 hydraulic oil leakage orifice.
[0049]
That is, in the second embodiment, the plunger 9 is formed with a through hole 21 penetrating from the tip 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. A plug 23 is press-fitted into the hole 21.
[0050]
In addition, the orifice which consists of a spiral groove may be formed in the outer periphery of the plug body 23, and the plug body 23 may be press-fitted in the through-hole having the same diameter throughout the axial direction.
[0051]
In the hydraulic chain tensioner configured as described above, the housing 1 is attached to the cylinder block so that the plunger 9 is inclined with a slight upward slope toward the tip, and when the plunger 9 is pushed in, the hydraulic damper chamber 11 The hydraulic oil inside is leaked to the outside from both the leak gap 10 and the orifice 22 formed between the sliding surfaces of the guide hole 4 and the plunger 9.
[0052]
Also in the second embodiment, as in the first embodiment, the width of the leak clearance 10 with respect to an appropriate leak down time can be increased, and the processing cost can be reduced by increasing the processing tolerance. Can do.
[0053]
7 and 8 show a third embodiment of a hydraulic chain tensioner according to the present invention. In the hydraulic chain tensioner shown in this embodiment, a through hole 24 that penetrates the plunger 9 from the tip end surface to the spring accommodating hole 14 is formed, and a helical groove is formed on the outer periphery of the plug body 25 press-fitted into the through hole 24. The orifice 26 is formed. Further, a spring seat 27 for receiving the end of the return spring 12 is provided in the plug body 25, and a plurality of grooves 28 penetrating the orifice 26 are formed radially on the surface of the spring seat 27 on which the plug body 25 is provided. Yes.
[0054]
Since the other configuration 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.
[0055]
As described above, by providing the spring seat 27 integrally with the plug body 25, the spring seat 27 engages with the closed end of the spring accommodating hole 14, so that the plug body 25 can be reliably prevented from falling off. .
[0056]
Further, when the plunger 9 is pushed in, the hydraulic oil can be leaked from both the leak clearance 10 and the orifice 26. Therefore, the width of the leak clearance 10 with respect to an appropriate leak down time is widened, and the machining tolerance is increased. Cost can be reduced.
[0057]
FIG. 9 shows a fourth embodiment of the hydraulic chain tensioner according to the present invention. This embodiment is different from the hydraulic chain tensioner shown in FIG. 7 only in the shape of the return spring 12. That is, in this embodiment, the return spring 12 is tapered and the tip that presses the plunger 9 has a small diameter.
[0058]
As described above, when the return spring 12 is tapered, a wedge-shaped gap 29 can be formed between the distal end portion of the return spring 12 and the inner periphery of the spring accommodating hole 14, so that air mixed into the hydraulic oil is not mixed. It is easy to accumulate in the gap 29, and the air mixed in the hydraulic oil can be smoothly flowed out from the orifice 26 together with the hydraulic oil, and the reduction of the hydraulic damper effect can be suppressed.
[0059]
In the fourth embodiment, the return spring 12 is tapered, and a wedge-shaped gap 29 is formed between the tip of the return spring 12 and the inner periphery of the spring accommodating hole 14. A 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 accommodating hole 14.
[0060]
FIGS. 10 (I) and (II) show a fifth embodiment of a hydraulic chain tensioner according to the present invention. In the fifth embodiment, a mounting piece 30 having a bolt insertion hole 31 is formed in the housing 1 and a positioning pin 32 is provided on an abutting surface of the housing 1 with respect to the cylinder block. The positioning pin 32 is attached to the cylinder block. The housing 1 is attached to the cylinder block by being inserted into the formed positioning hole and tightening the bolt inserted into the bolt insertion hole 31.
[0061]
As described above, by providing the positioning pin 32, as shown in FIG. 1, the mounting of the housing 1 can be facilitated as compared with the case where the two mounting pieces 2 are mounted to the cylinder block by tightening bolts. it can.
[0062]
FIG. 11 shows a sixth embodiment of the hydraulic chain tensioner according to the present invention. In this embodiment, a hollow pin 33 is press-fitted into an oil supply hole 5 formed in the housing 1, and the hollow pin 33 is press-fitted into an oil outlet of an oil supply passage formed in a cylinder block to position the housing 1. 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 bolt.
[0063]
As described above, since the oil supply passage formed in the cylinder block can be used as the positioning hole by press-fitting the hollow pin 33 into the oil supply hole 5, there is no need to separately process the positioning hole in the cylinder block. Processing can be facilitated.
[0064]
【The invention's effect】
As described above, according to the present invention, the hydraulic oil in the hydraulic damper chamber is leaked from both the orifice and the leak gap when the plunger is retracted, so that the width of the leak gap corresponding to an appropriate leak down time is widened. Accordingly, the machining tolerance when machining the inner diameter of the guide hole and the outer diameter of the plunger is increased, machining with high dimensional accuracy is not required for machining each surface, and machining cost can be reduced.
[0065]
In addition, since the tip of the return spring that suppresses the plunger has a small diameter and a gap is formed between the tip and the inner periphery of the spring accommodation hole formed in the plunger, air mixed into the hydraulic oil is collected in the gap. It becomes easy and the said air can be smoothly flowed outside with hydraulic fluid from the orifice formed in the front-end | tip part of a plunger.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view showing a first embodiment of a hydraulic chain tensioner according to the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is an enlarged sectional view showing a part of the plunger of the hydraulic chain tensioner shown in FIG. 1;
FIG. 5 is a graph showing the relationship between the leak clearance and the leak down time of the hydraulic chain tensioner
FIG. 6 is a longitudinal front view showing a second embodiment of the hydraulic chain tensioner according to the present invention.
FIG. 7 is a cross-sectional view showing a third embodiment of the hydraulic chain tensioner according to the present invention.
8 is a cross-sectional view taken along line VIII-VIII in FIG.
FIG. 9 is a longitudinal 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 a hydraulic chain tensioner according to the present invention.
[Explanation of symbols]
1 Housing
4 Guide hole
5 Refueling 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 Circumferential groove
15a engagement surface
15b Tapered surface
16 Stopper surface
17 Stopper groove
18 Orifice
19 Through hole
20 Plug body
21 Through hole
22 Orifice
23 Plug
24 Through hole
25 Plug body
26 Orifice
27 Spring seat
28 groove
29 Gap

Claims (6)

The housing has a bottomed guide hole and an oil supply hole that opens at the bottom of the guide hole, a plunger is slidably incorporated in the guide hole, and a hydraulic damper chamber is provided on the back thereof. Are assembled with a return spring that presses the plunger outward and a check valve that prevents the hydraulic oil in the hydraulic damper chamber from flowing back to the oil supply hole side. Hydraulic chain tensioner that leaks to the outside through a leak clearance formed between the sliding surface of the guide hole and the guide hole, and hydraulic oil leak that causes the hydraulic damper chamber and the outside to communicate with either the housing or the plunger the orifice of use provided, Rejisutaku the guide hole clip mounting groove provided in the peripheral opening of the clip mounting groove A ring portion that is elastically deformable in a radial direction provided in the cup is mounted, and a plurality of circumferential grooves that are tightened by the ring portion of the register clip are formed at intervals in the axial direction on the outer periphery of the plunger. A taper surface that expands the diameter of the ring portion of the register clip when the plunger moves forward, and an engagement surface that engages the ring portion of the register clip when the plunger moves backward to prevent the plunger from moving backward on the outer periphery of each circumferential groove. A stopper surface for holding the plunger in the initial set state by pushing the plunger into the guide hole by abutting against the ring portion of the register clip on the front side of the most circumferential groove arranged in the axial direction of the plunger. hydraulic chain tensioner, characterized in that the provided. The stopper groove for preventing the plunger from coming off by engagement with the ring portion of the register clip is provided on the rear side of the circumferential groove at the rearmost end of the plurality of circumferential grooves arranged in the axial direction on the outer periphery of the plunger. Hydraulic chain tensioner. A circular through hole penetrating from the upper outer periphery of the housing to the hydraulic damper chamber is provided, a plug is press-fitted into the through hole, and an orifice comprising a spiral groove is provided on one of the outer periphery of the plug and the inner periphery of the through hole. The hydraulic chain tensioner according to claim 1 or 2 . The plunger is provided with a spring accommodating hole for accommodating a return spring and a circular through hole communicating with the spring accommodating hole from the front end surface, and a shaft-shaped plug body is press-fitted into the through hole, and the outer peripheral surface of the plug body The hydraulic chain tensioner according to any one of claims 1 to 3, wherein an orifice including a spiral groove is provided on one of the inner peripheral surfaces of the through holes . 5. The hydraulic chain according to claim 4 , wherein a spring seat for receiving an end portion of a return spring is integrally provided on the plug body, and a radial groove communicating with the orifice is provided on a surface of the spring seat on which the plug body is provided. Tensioner. The hydraulic chain tensioner according to claim 4 or 5 , wherein an end of the return spring on the side pressing the plunger has a small diameter .

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