JP2022045528A - Chain tensioner - Google Patents

Abstract

To provide a chain tensioner which is small in a consumption amount of oil, hardly causes the lowering of a damper force even if attached in a depression angle state, and is low in a manufacturing cost.SOLUTION: A chain tensioner comprises a second check valve 17 arranged at an end part in an axial direction at a side apart from a protrusion end protruding from a cylinder 9 of a plunger 10 of a pressure chamber 16, and a second reservoir chamber 18 communicating with the pressure chamber 16 via the second check valve 17. The second check valve 17 is constituted so as to permit only the movement of oil to a side of the pressure chamber 16 from a side of the second reservoir chamber 18, and an orifice passage 56 for making the second reservoir chamber 18 and the pressure chamber 16 communicate with each other is arranged in parallel with the second check valve 17.SELECTED DRAWING: Figure 2

Description

The present invention relates to a chain tensioner used to hold the tension of a chain.

Chain transmission devices used in engines such as automobiles include, for example, those that transmit the rotation of the crankshaft to the camshaft, and those that transmit the rotation of the crankshaft to auxiliary equipment such as oil pumps, water pumps, and superchargers. , The one that transmits the rotation of the crankshaft to the balancer shaft, and the one that connects the intake cam and the exhaust cam of the twin cam engine to each other. Chain tensioners are used to keep the chain tension in these chain transmissions within the proper range.

As a chain tensioner used for such an application, for example, the one described in Patent Document 1 is known. The chain tensioner of Patent Document 1 includes a cylindrical cylinder having one end in the axial direction as a closed end and an open end at the other end in the axial direction, a plunger inserted into the cylinder so as to be slidable in the axial direction, and a plunger. It has a return spring that urges in the direction of protrusion from the cylinder.

The plunger is formed in a cylindrical shape in which the insertion end into the cylinder is open and the protruding end from the cylinder is closed. The space surrounded by the cylinder and the plunger is axially divided into a reservoir chamber and a pressure chamber by a check valve provided fixed to the inner circumference of the plunger so as to move in the axial direction integrally with the plunger. A refueling passage for introducing oil supplied from the outside of the cylinder is connected to the reservoir chamber. A leak gap is formed between the outer circumference of the plunger and the inner circumference of the cylinder to allow oil to leak from the pressure chamber. The refueling passage is connected to the outlet side end of the leak gap so as to return the oil leaked from the pressure chamber through the leak gap to the refueling passage.

In the chain tensioner of Patent Document 1, when the tension of the chain becomes large during engine operation, the tension of the chain causes the plunger to move in the direction of being pushed into the cylinder (hereinafter referred to as "pushing direction"), and the tension of the chain is increased. To absorb. At this time, the oil in the pressure chamber flows out through the leak gap, and a damper force is generated by the viscous resistance of the oil, so that the plunger moves slowly.

On the other hand, when the tension of the chain becomes small while the engine is operating, the urging force of the return spring causes the plunger to move in the direction of protrusion from the cylinder (hereinafter referred to as "protrusion direction") to absorb the slack of the chain. At this time, the check valve opens and oil flows from the reservoir chamber into the pressure chamber, so that the plunger moves quickly.

Here, in this chain tensioner, when the plunger moves in the pushing direction according to the tension of the chain, the oil leaked from the pressure chamber through the leak gap returns to the refueling passage, so that the oil is discharged from the chain tensioner to the outside. The amount of oil is small, and it is possible to reduce the amount of oil consumed by the chain tensioner.

However, when the chain tensioner of Patent Document 1 is attached in a depression angle state (a state in which the protrusion direction from the cylinder of the plunger is diagonally downward), air in the pressure chamber is difficult to be discharged, and a decrease in damper force is likely to occur. There is a problem.

That is, in the chain tensioner of Patent Document 1, the reservoir chamber is arranged on the side close to the protruding end from the cylinder of the plunger, and the pressure chamber is arranged on the side far from the protruding end from the cylinder of the plunger, so that the chain tensioner protrudes from the cylinder of the plunger. If air is mixed into the oil supplied to the chain tensioner through the oil passage when the oil is installed in a state where the direction is diagonally downward, the air tends to collect in the pressure chamber and is difficult to be discharged from the pressure chamber. When air collects in the pressure chamber, when the tension of the chain increases, almost no oil flows in the leak gap, and the air existing in the pressure chamber compresses and the plunger moves, so it depends on the viscous resistance of the oil. Almost no damper force is generated, and the damper force is reduced.

Therefore, the inventor of the present application has already proposed Patent Document 2 as a chain tensioner that consumes less oil and is less likely to cause a decrease in damper force even when the chain tensioner is attached in a depression angle state. ..

The chain tensioner of Patent Document 2 includes a cylindrical cylinder having one end in the axial direction as a closed end and an open end at the other end in the axial direction, and a tubular plunger inserted into the cylinder so as to be slidable in the axial direction. It has an inner sleeve that is slidably fitted to the inner circumference of the plunger in the axial direction. The inner sleeve is incorporated with one end protruding from the plunger and the other end inserted into the plunger.

Here, the protruding end of the inner sleeve from the plunger is supported by the closed end of the cylinder. Further, at the insertion end of the inner sleeve into the plunger, a check valve is provided to divide the space surrounded by the plunger and the inner sleeve into a reservoir chamber inside the inner sleeve and a pressure chamber inside the plunger. There is. A refueling passage for introducing oil supplied from the outside of the cylinder is connected to the reservoir chamber. A leak gap is formed between the outer circumference of the inner sleeve and the inner circumference of the plunger to allow oil to leak from the pressure chamber. The refueling passage is connected to the outlet side end of the leak gap so as to return the oil leaked from the pressure chamber through the leak gap to the refueling passage.

In the chain tensioner of Patent Document 2, when the plunger moves in the pushing direction according to the tension of the chain, the oil leaked from the pressure chamber through the leak gap returns to the refueling passage, so that the oil is discharged to the outside from the chain tensioner. The amount of oil is small, and it is possible to reduce the amount of oil consumed by the chain tensioner.

Further, in the chain tensioner of Patent Document 2, the pressure chamber is arranged on the side close to the protruding end from the cylinder of the plunger, and the reservoir chamber is arranged on the side far from the protruding end from the cylinder of the plunger. Even if air is mixed in the oil supplied to the chain tensioner through the oil passage when the oil is installed so that the protrusion direction is diagonally downward, the air collects on the side of the reservoir chamber and is unlikely to accumulate in the pressure chamber. Moreover, even if air is mixed in the pressure chamber, the air can be smoothly discharged.

Japanese Unexamined Patent Publication No. 2015-183767 Japanese Unexamined Patent Publication No. 2019-152285

The inventor of the present application has faced a problem that when manufacturing the chain tensioner of Patent Document 2, there are many parts where high dimensional accuracy is required, and the manufacturing cost of the chain tensioner is high.

That is, the chain tensioner of Patent Document 2 has a plunger slidably inserted into the cylinder and incorporates an inner sleeve having an outer circumference that is in sliding contact with the inner circumference of the plunger. Here, the position where the gap (leak gap) between the outer circumference of the inner sleeve and the inner circumference of the plunger and the gap between the outer circumference of the plunger and the inner circumference of the cylinder overlap in the radial direction on the inner diameter side and the outer diameter side. Exists in. In order to accurately control the dimensions of these two gaps, it is necessary to process all the surfaces of the inner circumference of the cylinder, the outer circumference of the plunger, the inner circumference of the plunger, and the outer circumference of the inner sleeve with high precision. , Management costs for those dimensions are required.

As described above, the chain tensioner of Patent Document 2 has a feature that the consumption of oil is small and the damper force is unlikely to decrease even when the chain tensioner is mounted in a depression angle state, but high dimensional accuracy is required. There is a problem that there are many parts and the manufacturing cost of the chain tensioner is high.

An object to be solved by the present invention is to provide a chain tensioner having a low oil consumption, a decrease in damper force even when mounted in a depression angle state, and a low manufacturing cost.

In order to solve the above problems, the present invention provides a chain tensioner having the following configuration.
A cylindrical cylinder with one end in the axial direction as the closed end and the other end in the axial direction as the open end.
A tubular plunger that is slidably inserted into the cylinder in the axial direction, the insertion end into the cylinder is opened, and the protruding end from the cylinder is closed.
A return spring that urges the plunger in a direction protruding from the cylinder,
The space surrounded by the cylinder and the plunger, which is fixedly provided on the inner circumference of the plunger so as to move in the axial direction integrally with the plunger, is the first side of the plunger near the protruding end from the cylinder. A second reservoir chamber and a pressure chamber on the side far from the protruding end from the cylinder of the plunger are partitioned in the axial direction, and only the movement of oil from the side of the first reservoir chamber to the side of the pressure chamber is allowed. 1 check valve and
A refueling passage that introduces oil supplied from the outside of the cylinder into the first reservoir chamber, and
It has a leak gap formed between the outer circumference of the plunger and the inner circumference of the cylinder to leak oil from the pressure chamber when the plunger moves in the direction of being pushed into the cylinder.
The refueling passage is a chain tensioner provided in connection with the outlet side end of the leak gap so as to return the oil leaked from the pressure chamber through the leak gap to the refueling passage.
A second check valve located at the axial end of the pressure chamber on the side far from the protruding end of the plunger from the cylinder.
A second reservoir chamber communicating with the pressure chamber via the second check valve is provided.
The second check valve is configured to allow only the movement of oil from the side of the second reservoir chamber to the side of the pressure chamber.
A chain tensioner comprising an orifice passage communicating between the second reservoir chamber and the pressure chamber in parallel with the second check valve.

In this way, when the plunger moves in the pushing direction according to the tension of the chain, the oil leaked from the pressure chamber through the leak gap returns to the refueling passage, so that the amount of oil discharged from the chain tensioner to the outside. It is possible to reduce the amount of oil consumed by the chain tensioner.

Further, since the pressure chamber is arranged on the side close to the protruding end from the cylinder of the plunger and the second reservoir chamber is arranged on the side far from the protruding end from the cylinder of the plunger, the protruding direction from the cylinder of the plunger is diagonally downward. Even if air is mixed in the oil supplied to the chain tensioner when it is installed in the above state, the air is released from the pressure chamber through the orifice passage to the second reservoir chamber, and the air collects in the pressure chamber. Hateful. Therefore, even when the chain tensioner is attached in the depression angle state, the damper force is unlikely to decrease.

Also, in general, when the engine is stopped, the oil pump of the engine stops and the oil level in the oil passage that supplies oil to the chain tensioner drops once, so when the engine restarts, it goes to the chain tensioner. It may take some time before the oil supply starts. Here, if the chain tensioner does not generate a damper force due to the oil until the supply of oil to the chain tensioner starts, the tension of the chain will cause the plunger of the chain tensioner to be greatly pushed into the cylinder, resulting in a chain. There is a risk of fluttering. In response to this problem, the chain tensioner that adopts the above configuration promptly generates damper force by introducing oil from the second reservoir chamber to the pressure chamber through the second check valve immediately after starting the engine. It is possible to do.

Further, since the only member that slides with the plunger is the cylinder and there is no inner sleeve that is in sliding contact with the inner circumference of the plunger, the manufacturing cost can be kept low.

It is preferable to provide an air bleeding passage for communicating the second reservoir chamber with the outside of the cylinder.

In this way, the air that has escaped from the pressure chamber through the orifice passage to the second reservoir chamber can be discharged from the second reservoir chamber through the air bleeding passage.

The air bleeding passage employs a spiral screw gap formed between a screw hole formed through the outside of the cylinder into the second reservoir chamber and a male screw member screwed into the screw hole. be able to.

In this way, since the screw gap has a small cross-sectional area and a long length, it is effective to allow oil having a higher viscous resistance than air to pass smoothly through the air bleeding passage. Can be restricted. Therefore, the oil consumption in the chain tensioner can be effectively suppressed.

As the air bleeding passage, it is also possible to adopt pores formed by penetrating the second reservoir chamber from the outside of the cylinder.

The first check valve includes a first valve seat fixed to the inner circumference of the plunger, a first valve hole formed so as to penetrate the first valve seat in the axial direction, and the first valve seat. It is provided so as to be movable in the axial direction between the valve closing position for closing the valve hole and the valve opening position moving in the axial direction on the side away from the protruding end of the plunger from the cylinder with respect to the valve closing position. A configuration having a first valve body can be adopted.

In this case, in the first check valve, when the first valve body is in the closed position, the first valve body is exposed to gravity and oil pressure due to the weight of the first valve body. It is preferable to configure it so that only works.

In this way, since the force required for the first valve body to move from the valve closed position to the valve open position is small, the response of the first check valve to the pressure fluctuation of the pressure chamber becomes high, and the chain It is possible to effectively improve the followability of the plunger to the tension fluctuation of.

The second check valve includes a second valve seat fixed to the inner circumference of the cylinder, a second valve hole formed so as to penetrate the second valve seat in the axial direction, and the second valve seat. It is provided so as to be movable in the axial direction between the valve closing position for closing the valve hole and the valve opening position moved in the axial direction on the side closer to the protruding end from the cylinder of the plunger with respect to the valve closing position. The second valve body has a second valve body and a second valve spring that urges the second valve body in the axial direction on the side away from the protruding end of the plunger from the cylinder, and the second valve body has the second valve body. It is preferable to configure the second valve body so that the urging force of the second valve spring acts on the second valve body when the valve is in the closed position.

In this way, the second valve body is held in the valve closed position by the urging force of the second valve spring, so that even when the oil level in the pressure chamber drops once when the engine is stopped, the second valve body is held. It is possible to prevent the oil from flowing out from the reservoir chamber to the pressure chamber, and it is possible to retain the oil in the second reservoir chamber. Therefore, immediately after the engine is started, oil can be introduced from the second reservoir chamber to the pressure chamber through the second check valve, and a damper force can be reliably generated.

The axial movement stroke between the valve closing position and the valve opening position of the second valve body is larger than the axial moving stroke between the valve closing position and the valve opening position of the first valve body. It is preferable to set it large.

By doing so, when the second valve body moves to the valve opening position, the flow rate of the oil flowing from the second reservoir chamber to the pressure chamber becomes large, so that the damper force is generated particularly quickly immediately after the engine is started. It becomes possible to do.

It is preferable to assemble a seal member that is in sliding contact with the seal groove formed in one of the inner circumference of the cylinder and the outer circumference of the plunger, which is closer to the protruding end from the cylinder of the plunger than the leak gap.

By doing so, it becomes possible to suppress the oil consumption in the chain tensioner extremely effectively.

The leak gap is a first gap formed at the end of the annular gap between the outer circumference of the plunger and the inner circumference of the cylinder, which is closer to the insertion end of the plunger into the cylinder. ,
Of the annular gap between the outer circumference of the plunger and the inner circumference of the cylinder, the first gap is formed on the portion farther from the insertion end of the plunger into the cylinder with respect to the first gap. An enlarged gap with a gap dimension larger than the gap, and
Of the annular gap between the outer periphery of the plunger and the inner circumference of the cylinder, the portion far from the insertion end of the plunger into the cylinder with respect to the enlarged gap portion is formed from the expanded gap portion. Further has a second gap, which also has a small gap dimension,
The oil supply passage includes a cylinder-side oil passage formed in the cylinder so as to introduce oil supplied from the outside of the cylinder into the expanded gap, the expanded gap, the expanded gap, and the first. It can be composed of a plunger-side oil passage formed so as to communicate between the reservoir chambers of the plunger from the outer periphery to the inner circumference of the plunger.

By doing so, it is possible to maintain communication between the cylinder-side oil passage and the plunger-side oil passage through the enlarged gap even when the axial position of the plunger with respect to the cylinder changes. Further, it is possible to return the oil leaking from the pressure chamber through the first gap (leak gap) between the outer circumference of the plunger and the inner circumference of the cylinder to the refueling passage (enlarged gap portion).

A cylindrical first large-diameter outer diameter surface is formed at the end of the outer circumference of the plunger near the insertion end of the plunger into the cylinder.
The outer circumference of the plunger farther from the insertion end of the plunger into the cylinder with respect to the first large-diameter outer diameter surface, which is smaller than the first large-diameter outer diameter surface. A small diameter outer diameter surface with a diameter dimension is formed,
A second portion of the outer periphery of the plunger that is far from the insertion end of the plunger into the cylinder with respect to the small diameter outer diameter surface and has the same outer diameter dimension as the first large diameter outer diameter surface. A large diameter outer diameter surface of 2 is formed,
The first gap is a gap formed between the first large-diameter outer diameter surface and the inner circumference of the cylinder.
The enlarged gap portion is a gap formed between the small diameter outer diameter surface and the inner circumference of the cylinder.
It is preferable to adopt a configuration in which the second gap is a gap formed between the second large-diameter outer diameter surface and the inner circumference of the cylinder.

By doing so, even when the plunger moves in the axial direction with respect to the cylinder, the axial length of the leak gap does not change and is constant, so that a damper force having a stable magnitude can be obtained.

In the chain tensioner of the present invention, when the plunger moves in the pushing direction according to the tension of the chain, the oil leaked from the pressure chamber through the leak gap returns to the refueling passage, so that the oil is discharged from the chain tensioner to the outside. It is possible to reduce the amount of oil consumed by the chain tensioner. Further, since the pressure chamber is arranged on the side close to the protruding end from the cylinder of the plunger and the second reservoir chamber is arranged on the side far from the protruding end from the cylinder of the plunger, the protruding direction from the cylinder of the plunger is diagonally downward. Even if air is mixed in the oil supplied to the chain tensioner when it is installed in the above state, the air is released from the pressure chamber through the orifice passage to the second reservoir chamber, and the air collects in the pressure chamber. Hateful. Therefore, even when the chain tensioner is attached in the depression angle state, the damper force is unlikely to decrease. Further, by introducing oil from the second reservoir chamber to the pressure chamber through the second check valve immediately after starting the engine, it is possible to quickly generate a damper force. Further, since the only member that slides with the plunger is the cylinder and there is no inner sleeve that is in sliding contact with the inner circumference of the plunger, the manufacturing cost can be kept low.

The figure which shows the chain transmission device which incorporated the chain tensioner of 1st Embodiment of this invention. Enlarged sectional view of the vicinity of the chain tensioner in FIG. Enlarged sectional view of the vicinity of the first check valve and the second check valve in FIG. Sectional view taken along line IV-IV of FIG. Sectional drawing along VV line of FIG. Sectional drawing along the VI-VI line of FIG. Sectional drawing which shows the neighborhood of the plunger of the chain tensioner of 2nd Embodiment of this invention. Sectional drawing which shows the vicinity of the air bleeding passage of the chain tensioner of 3rd Embodiment of this invention. Sectional drawing which shows the neighborhood of the plunger of the chain tensioner of 4th Embodiment of this invention. The figure explaining the operation of the 2nd check valve and the air bleeding passage shown in FIG. Sectional drawing which shows the modification of the orifice passage shown in FIG. Cross-sectional view showing another modification of the orifice passage shown in FIG. Cross-sectional view showing still another modification of the orifice passage shown in FIG.

FIG. 1 shows a chain transmission device incorporating the chain tensioner 1 according to the first embodiment of the present invention. In this chain transmission device, a sprocket 3 fixed to the crankshaft 2 of the engine and a sprocket 5 fixed to the camshaft 4 are connected via a chain 6, and the chain 6 rotates the crankshaft 2. It is transmitted to the camshaft 4, and the valve (not shown) in the combustion chamber is opened and closed by the rotation of the camshaft 4.

The rotation direction of the crankshaft 2 when the engine is operating is constant (rotation to the right in the figure), and at this time, the chain 6 is pulled into the sprocket 3 with the rotation of the crankshaft 2 (right side in the figure). The portion of is the tension side, and the portion of the side (left side in the figure) sent out from the sprocket 3 is the slack side. A chain guide 8 swingably supported around the fulcrum shaft 7 is in contact with the slack side portion of the chain 6. The chain tensioner 1 presses the chain 6 via the chain guide 8.

As shown in FIG. 2, the chain tensioner 1 is slidably inserted into a cylindrical cylinder 9 having one end in the axial direction as a closed end and the other end in the axial direction as an open end, and the cylinder 9. It has a plunger 10. The protruding end of the plunger 10 from the cylinder 9 presses the chain guide 8.

The cylinder 9 is integrally molded with a metal (for example, an aluminum alloy). The cylinder 9 has an engine wall surface in a state in which the protrusion direction of the plunger 10 from the cylinder 9 is diagonally downward (depression angle state) by tightening the bolt 12 to a plurality of mounting pieces 11 integrally formed on the outer periphery of the cylinder 9. It is attached to 13 (see FIG. 6).

The plunger 10 is formed in a cylindrical shape in which the insertion end of the plunger 10 into the cylinder 9 is open and the protruding end of the plunger 10 from the cylinder 9 is closed. The material of the plunger 10 is an iron-based material (for example, a steel material such as SCM (chrome molybdenum steel) or SCr (chrome steel)).

A first check valve 14 is fixedly provided on the inner circumference of the insertion portion of the plunger 10 into the cylinder 9 so as to move in the axial direction integrally with the plunger 10. The first check valve 14 forms a space surrounded by the cylinder 9 and the plunger 10 with the first reservoir chamber 15 on the side close to the protruding end of the plunger 10 from the cylinder 9 and the protruding end of the plunger 10 from the cylinder 9. It is axially partitioned from the pressure chamber 16 on the side far from the pressure chamber 16.

The pressure chamber 16 is a space portion whose volume changes with the axial movement of the plunger 10, and the first reservoir chamber 15 is a space portion whose volume does not change even when the plunger 10 moves in the axial direction. When the plunger 10 moves axially to the side protruding from the cylinder 9, the volume of the pressure chamber 16 expands, and when the plunger 10 moves axially to the side pushed into the cylinder 9, the volume of the pressure chamber 16 decreases. .. The first check valve 14 limits the movement of oil from the side of the pressure chamber 16 to the side of the first reservoir chamber 15, and the movement of oil from the side of the first reservoir chamber 15 to the side of the pressure chamber 16. It is configured to allow only.

A second check valve 17 is provided at the axial end of the pressure chamber 16 on the side far from the protruding end of the plunger 10 from the cylinder 9. Further, inside the cylinder 9, a second reservoir chamber 18 partitioned by a second check valve 17 is provided on the side far from the protruding end of the plunger 10 from the cylinder 9 with respect to the pressure chamber 16. There is.

The second reservoir chamber 18 is a region surrounded by a bottomed cylindrical end on the closed end side of the cylinder 9. Here, the second reservoir chamber 18 is formed in a cylindrical shape, and its inner diameter is larger than the inner diameter of the second valve hole 46 (see FIG. 3). The inner diameter of the second reservoir chamber 18 can be set to be twice or more (preferably 2.5 times or more) the inner diameter of the second valve hole 46.

The second reservoir chamber 18 communicates with the pressure chamber 16 via the second check valve 17. The second check valve 17 limits the movement of oil from the side of the pressure chamber 16 to the side of the second reservoir chamber 18, and the movement of oil from the side of the second reservoir chamber 18 to the side of the pressure chamber 16. It is configured to allow only.

Here, in the space surrounded by the cylinder 9 and the plunger 10, the first reservoir chamber 15, the pressure chamber 16, and the second reservoir are directed from the side closer to the far side from the protruding end of the plunger 10 from the cylinder 9. The chambers 18 are formed in order in the axial direction, the space between the first reservoir chamber 15 and the pressure chamber 16 is partitioned by the first check valve 14, and the space between the second reservoir chamber 18 and the pressure chamber 16 is second. It is configured to be partitioned by the check valve 17 of. The first check valve 14 and the second check valve 17 are arranged so as to face each other in the axial direction.

At the closed end of the cylinder 9, an air bleeding passage 19 for communicating the second reservoir chamber 18 to the outside of the cylinder 9 is provided. In this embodiment, the air bleeding passage 19 is a spiral formed between a screw hole 20 formed through the outside of the cylinder 9 through the second reservoir chamber 18 and a male screw member 21 screwed into the screw hole 20. It is a screw gap in the shape. The end of the air bleeding passage 19 on the side of the second reservoir chamber 18 is the upper portion of the end of the second reservoir 18 on the side far from the protruding end of the plunger 10 from the cylinder 9 (left side in the figure). Communicate with.

A return spring 22 is incorporated in the pressure chamber 16. The return spring 22 is a compression coil spring in which a metal wire is spirally wound. One end of the return spring 22 is supported by the second check valve 17, and the other end presses the plunger 10 in the axial direction via the first check valve 14, and the pressing causes the plunger 10 to protrude from the cylinder 9. It is urging in the direction.

On the outer circumference of the plunger 10, the first large-diameter outer diameter surface 23 and the small-diameter outer diameter are arranged in order from the side closer to the insertion end of the plunger 10 into the cylinder 9 (left side in the figure) to the far side (right side in the figure). A diameter surface 24 and a second large diameter outer diameter surface 25 are formed. Here, the first large-diameter outer diameter surface 23 is a cylindrical outer diameter surface formed on the outer peripheral portion of the plunger 10 on the side closer to the insertion end of the plunger 10 into the cylinder 9. Further, the small diameter outer diameter surface 24 is formed on a portion of the outer periphery of the plunger 10 adjacent to the first large diameter outer diameter surface 23 on the side far from the insertion end of the plunger 10 into the cylinder 9. , An outer diameter surface having an outer diameter dimension smaller than that of the first large diameter outer diameter surface 23. Further, the second large-diameter outer diameter surface 25 is formed on a portion of the outer periphery of the plunger 10 adjacent to the small-diameter outer diameter surface 24 on the side far from the insertion end of the plunger 10 into the cylinder 9. , A cylindrical outer diameter surface having the same outer diameter dimension as the first large diameter outer diameter surface 23. That is, the first large-diameter outer diameter surface 23 and the second large-diameter outer diameter surface 25 are cylindrical surfaces processed in the same process.

A first gap 26 is formed between the first large-diameter outer diameter surface 23 of the plunger 10 and the inner circumference of the cylinder 9. The first gap 26 is a portion formed at the end of the annular gap between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9 on the side closer to the insertion end of the plunger 10 into the cylinder 9. The first gap 26 constitutes a leak gap that allows oil to leak from the pressure chamber 16 when the plunger 10 moves in the direction of being pushed into the cylinder 9. The first gap 26 (leak gap) is a constant gap in which the cross-sectional shape orthogonal to the axis does not change along the axial direction, and is, for example, a cylindrical gap. Here, a cylindrical minute gap whose width in the radial direction is set in the range of 0.015 to 0.080 mm is adopted.

An enlarged gap 27 is formed between the small diameter outer diameter surface 24 of the plunger 10 and the inner circumference of the cylinder 9. The enlarged gap 27 is adjacent to the first gap 26 of the annular gap between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9 on the side far from the insertion end of the plunger 10 into the cylinder 9. It is a portion that is formed and has a gap size larger than that of the first gap 26. The axial length of the enlarged gap 27 is set to be longer than the moving stroke of the plunger 10 with respect to the time extension of the chain 6, and is set to, for example, 10 mm or more.

A second gap 28 is formed between the second large-diameter outer diameter surface 25 of the plunger 10 and the inner circumference of the cylinder 9. The second gap 28 is adjacent to the annular gap between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9 on the side far from the insertion end of the plunger 10 into the cylinder 9 with respect to the enlarged gap portion 27. It is a portion that is formed and has a gap size smaller than that of the enlarged gap portion 27. The second gap 28 is a cylindrical minute gap whose radial width is set in the range of 0.015 to 0.080 mm.

As shown in FIG. 6, the cylinder 9 and the plunger 10 are provided with a refueling passage 30 for introducing oil supplied from the outside of the cylinder 9 into the first reservoir chamber 15. The oil supply passage 30 includes a cylinder-side oil passage 31 formed in the cylinder 9 so as to introduce oil supplied from the outside of the cylinder 9 into the expanded gap 27, an expanded gap 27, an expanded gap 27, and a first. It is composed of a plunger side oil passage 32 formed in the plunger 10 so as to communicate between the reservoir chambers 15.

The cylinder-side oil passage 31 is a hole formed from the outer periphery of the cylinder 9 to the inner circumference. The inlet of the cylinder-side oil passage 31 opens to the seat surface 34 on the outer periphery of the cylinder 9 so as to connect to the oil hole 33 that opens in the engine wall surface 13. The seat surface 34 is a mating surface with respect to the engine wall surface 13. The seat surface 34 is formed in a plane shape parallel to the axis of the cylinder 9, and the seat surface 34 is attached and fixed to the engine wall surface 13 extending vertically. The oil hole 33 is a hole for supplying oil to the chain tensioner 1 to supply oil sent from an oil pump (not shown).

The plunger side oil passage 32 is a hole formed through the outer circumference of the tubular plunger 10 to the inner circumference. The end portion of the plunger side oil passage 32 on the outer peripheral side of the plunger 10 is open within the range of the small diameter outer diameter surface 24 of the plunger 10.

Here, the enlarged gap 27 constituting the oil supply passage 30 is arranged so as to be connected to the outlet side end of the first gap 26 (leak gap), whereby the pressure chamber 16 to the first gap 26 are arranged. The oil leaked through the (leak gap) joins the refueling passage 30 (enlarged gap 27) and returns.

As shown in FIG. 3, the first check valve 14 is formed by axially penetrating a first valve seat 35 fixed to the inner circumference of the plunger 10 and a first valve seat 35. It has a valve hole 36, a first valve body 37 that opens and closes the first valve hole 36, and a first valve retainer 38 that regulates the movement range of the first valve body 37.

The first valve body 37 is formed in a spherical shape. The first valve body 37 moves in the axial direction of the valve closing position for closing the first valve hole 36 and the side (left side in the figure) away from the protruding end of the plunger 10 from the cylinder 9 with respect to the valve closing position. It is provided so as to be movable in the axial direction from the valve opening position received by the first valve retainer 38.

The first valve retainer 38 is a side away from the first flange portion 40 supported by the first valve seat 35 and the protruding end of the plunger 10 from the cylinder 9 from the first flange portion 40 (left side in the figure). The first cylinder portion 41 extending in the axial direction and accommodating the first valve body 37 so as to be movable in the axial direction, and the side of the first cylinder portion 41 away from the protruding end of the plunger 10 from the cylinder 9 (FIG. On the left side), it is composed of a first end plate 42 provided at the axial end portion.

The first flange portion 40 is axially sandwiched and fixed between the return spring 22 and the first valve seat 35. The first valve retainer 38 has an opening 43 for oil passage (in the figure, a first cylinder portion 41 and a first flange portion 40) so that oil can pass from the inside to the outside of the first cylinder portion 41. A slit) that divides in the circumferential direction is formed. The first end plate 42 is a portion that receives the first valve body 37 when the first valve body 37 moves in the axial direction on the side away from the protruding end of the plunger 10 from the cylinder 9 (left side in the figure). Is.

Here, the first check valve 14 has the first valve body 37 in the closed position (position shown in the figure) when the first valve body 37 is in the closed position (position shown in the figure) due to the own weight of the first valve body 37. It is configured so that only gravity and oil pressure act. That is, the first check valve 14 has a spring (a member corresponding to the second valve spring 49 of the second check valve 17) that urges the first valve body 37 from the valve opening position to the valve closing position. ) Is not provided.

The second check valve 17 includes a second valve seat 45 fixed to the inner circumference of the cylinder 9, a second valve hole 46 formed so as to penetrate the second valve seat 45 in the axial direction, and a second valve seat 45. A second valve body 47 that opens and closes the valve hole 46 of 2, a second valve retainer 48 that regulates the movement range of the second valve body 47, and a second valve spring that presses the second valve body 47. It has 49 and.

The second valve body 47 is formed in a spherical shape. The second valve body 47 moves in the axial direction of the valve closing position that closes the second valve hole 46 and the side (on the right side in the figure) that approaches the protruding end of the plunger 10 from the cylinder 9 with respect to the valve closing position. It is provided so as to be movable in the axial direction from the valve opening position received by the second valve retainer 48.

The second valve retainer 48 has a second flange portion 50 supported by the second valve seat 45 and a side approaching the protruding end of the plunger 10 from the cylinder 9 from the second flange portion 50 (right side in the figure). A second cylinder portion 51 extending in the axial direction and accommodating the second valve body 47 so as to be movable in the axial direction, and a side of the second cylinder portion 51 approaching the protruding end of the plunger 10 from the cylinder 9 (FIG. On the right side), it is composed of a second end plate 52 provided at the axial end portion.

The second flange portion 50 is axially sandwiched and fixed between the return spring 22 and the second valve seat 45. The second valve retainer 48 has an opening 53 for oil passage (in the figure, a second cylinder portion 51 and a second flange portion 50) so that oil can pass from the inside to the outside of the second cylinder portion 51. A slit) that divides in the circumferential direction is formed. The second end plate 52 is a portion that receives the second valve body 47 when the second valve body 47 moves in the axial direction on the side (right side in the figure) approaching the protruding end from the cylinder 9 of the plunger 10. Is.

The second valve spring 49 is incorporated between the second end plate 52 and the second valve body 47 in a state of being compressed in the axial direction. The second valve spring 49 urges the second valve body 47 in the axial direction on the side away from the protruding end of the plunger 10 from the cylinder 9 (left side in the figure).

Here, in the second check valve 17, when the second valve body 47 is in the valve closing position (position shown in the figure), the urging force of the second valve spring 49 is applied to the second valve body 47. It is configured to act and hold the second valve body 47 in the valve closed position by its urging force. That is, even when the plunger 10 is installed so that the protrusion direction from the cylinder 9 is vertically downward, the second valve body 47 does not move depending on the weight of the second valve body 47, and the second valve does not move. The urging force of the spring 49 keeps the second valve body 47 in the valve closed position.

Further, the axial movement stroke S2 between the valve closing position and the valve opening position of the _second valve body 47 is the axial movement between the valve closing position and the valve opening position of the first valve body 37. It is set to be larger _than the movement stroke S1.

An annular orifice seat 55 is incorporated between the second valve seat 45 and the step portion 54 formed on the inner circumference of the cylinder 9. The orifice sheet 55 forms an orifice passage 56 that communicates between the second reservoir chamber 18 and the pressure chamber 16. The orifice passage 56 is an elongated flow path formed so that the cross-sectional area of the flow path is smaller than the length of the flow path. The orifice passage 56 communicates between the second reservoir chamber 18 and the pressure chamber 16 in parallel with the second check valve 17. That is, the orifice passage 56 is provided so as to maintain communication between the second reservoir chamber 18 and the pressure chamber 16 even when the second valve body 47 is in the valve closed position.

As shown in FIG. 5, the second valve seat 45 has a cylindrical outer peripheral surface 57 and a notch portion 58 in which a part of the outer peripheral surface 57 is cut out. The outer peripheral surface 57 of the second valve seat 45 is fitted to the inner circumference of the cylinder 9. A tightening allowance is set between the outer peripheral surface 57 of the second valve seat 45 and the inner circumference of the cylinder 9, and the second valve seat 45 is fixed by this tightening allowance. In the figure, the notch portion 58 has a D-cut shape in which a part of the circumference is cut out along a plane parallel to the axis, but it may be a V-groove shape extending in the axial direction. Other shapes may be used.

As shown in FIG. 4, the orifice sheet 55 has a cylindrical outer peripheral surface 60 and a notch portion 61 in which a part of the outer peripheral surface 60 is cut out. The outer peripheral surface 60 of the orifice sheet 55 is fitted to the inner circumference of the cylinder 9. Further, a groove 63 extending in a spiral shape is formed on the mating surface 62 of the orifice seat 55 with respect to the second valve seat 45 (see FIG. 3). One end of the groove 63 is open to the inside of the notch, and the other end of the groove 63 is open to the inner circumference of the orifice sheet 55.

As shown in FIG. 3, the space between the inner surface of the groove 63 and the second valve seat 45 constitutes the orifice passage 56. Further, the notch 58 on the outer periphery of the second valve seat 45 and the notch 61 on the outer periphery of the orifice seat 55 ensure communication between the pressure chamber 16 and the orifice passage 56. When the groove 63 is formed so as to extend in a spiral shape as shown in FIG. 4, the length of the flow path of the orifice passage 56 can be effectively increased, but another shape such as a shape extending in a straight line is adopted. It is also possible.

Next, an operation example of this chain tensioner 1 will be described.

When the tension of the chain 6 shown in FIG. 1 becomes large while the engine is operating, the tension of the chain 6 causes the plunger 10 shown in FIG. 2 to move in the direction of being pushed into the cylinder 9 to absorb the tension of the chain 6. At this time, since the pressure in the pressure chamber 16 becomes higher than the pressure in the first reservoir chamber 15 and the second reservoir chamber 18, the first check valve 14 and the second check valve 17 are in a closed state. Further, since the volume of the pressure chamber 16 is reduced according to the movement of the plunger 10, oil leaks from the pressure chamber 16 through the first gap 26 (leak gap) to the enlarged gap portion 27 by the reduced volume. At this time, a damper force is generated by the viscous resistance of the oil flowing through the first gap 26 (leak gap), and the damper force prevents the chain 6 from fluttering. Then, the oil leaked from the pressure chamber 16 through the first gap 26 (leak gap) returns to the enlarged gap portion 27 (lubrication passage 30), further flows into the plunger side oil passage 32, or flows into the plunger side oil passage 32, or the cylinder side oil passage. It returns to 31 or lubricates between the sliding surface of the plunger 10 and the cylinder 9 through the second gap 28.

On the other hand, when the tension of the chain 6 shown in FIG. 1 becomes small while the engine is operating, the plunger 10 moves in the protruding direction by the urging force of the return spring 22 shown in FIG. 2 to absorb the slack of the chain 6. At this time, since the volume of the pressure chamber 16 expands according to the movement of the plunger 10, the pressure of the pressure chamber 16 becomes lower than the pressure of the first reservoir chamber 15, and the first check valve 14 opens. Then, oil flows from the first reservoir chamber 15 into the pressure chamber 16 through the first check valve 14, and the plunger 10 moves rapidly. At this time, oil is supplied to the first reservoir chamber 15 from the oil hole 33 (see FIG. 6) on the outside of the cylinder 9 through the oil supply passage 30 (cylinder side oil passage 31, enlarged gap 27, plunger side oil passage 32). Will be introduced.

Here, as shown by the chain line arrow in FIG. 10, while the engine is operating, the oil in the pressure chamber 16 flows into the second reservoir chamber 18 at a minute flow rate through the orifice passage 56. Further, the air in the second reservoir chamber 18 is discharged to the outside of the cylinder 9 through the air bleeding passage 19. Therefore, while the engine is operating, the second reservoir chamber 18 is filled with oil.

When the engine is stopped, the oil pump of the engine is stopped and the oil level of the oil in the oil hole 33 (see FIG. 6) drops once. Therefore, when the engine is restarted, the oil hole 33 is changed to the chain tensioner 1. It may take some time before the oil supply starts. Here, until the supply of oil from the oil hole 33 to the chain tensioner 1 starts, if the chain tensioner 1 does not generate a damper force due to the oil, the plunger 10 is caused by the tension of the chain 6 (see FIG. 1). The chain 6 may be fluttered due to being greatly pushed into the cylinder 9. In response to this problem, in the chain tensioner 1 of the embodiment, immediately after the engine is started, the oil previously accumulated in the second reservoir chamber 18 passes through the second check valve 17 as shown by the solid line arrow in FIG. Since it is supplied to the pressure chamber 16, it is possible to quickly generate a damper force.

The chain tensioner 1 leaks from the pressure chamber 16 through the first gap 26 (leak gap) when the plunger 10 shown in FIG. 2 moves in the pushing direction according to the tension of the chain 6 (see FIG. 1). Since the oil is returned to the lubrication passage 30 (that is, the oil circulates), the amount of oil discharged from the chain tensioner 1 to the outside is small, and it is possible to suppress the oil consumption in the chain tensioner 1.

Further, in this chain tensioner 1, the pressure chamber 16 is arranged on the side close to the protruding end of the plunger 10 from the cylinder 9, and the second reservoir chamber 18 is arranged on the side far from the protruding end of the plunger 10 from the cylinder 9. As shown in FIG. 2, even if air is mixed in the oil supplied to the chain tensioner 1 when the plunger 10 is installed in a state where the protrusion direction from the cylinder 9 is diagonally downward (depression angle state), the figure is shown. As shown by the chain line arrow of 10, the air is released from the pressure chamber 16 through the orifice passage 56 to the second reservoir chamber 18, and it is difficult for the air to collect in the pressure chamber 16. Therefore, even when the chain tensioner 1 is attached in the depression angle state, the damper force is unlikely to decrease.

Further, the chain tensioner 1 can quickly generate a damper force by introducing oil from the second reservoir chamber 18 to the pressure chamber 16 through the second check valve 17 immediately after the engine is started. Is.

Further, in this chain tensioner 1, the cylinder 9 is the only member that slides with the plunger 10, and there is no inner sleeve that is in sliding contact with the inner circumference of the plunger 10, so that the manufacturing cost can be kept low.

Further, since the chain tensioner 1 is provided with an air bleeding passage 19 for communicating the second reservoir chamber 18 to the outside of the cylinder 9, the pressure chamber 16 passes through the orifice passage 56 to the second reservoir chamber 18. The missed air can be discharged from the second reservoir chamber 18 through the air bleeding passage 19 as shown by the chain line arrow in FIG.

Further, this chain tensioner 1 employs a spiral screw gap formed between the male screw member 21 and the screw hole 20 as an air bleeding passage 19, and the screw gap has a small cross-sectional area and a long length. Therefore, it is possible to effectively restrict the passage of oil having a large viscous resistance as compared with the air while smoothly passing the air having an extremely small viscous resistance through the air bleeding passage 19. Therefore, the oil consumption in the chain tensioner 1 can be effectively suppressed.

Further, as shown in FIG. 3, the chain tensioner 1 is configured so that only gravity and oil pressure due to the weight of the first valve body 37 act on the first valve body 37 in the valve closed position. Since the first check valve 14 is adopted, the force required for the first valve body 37 to move from the valve closed position to the valve open position is small. Therefore, the responsiveness of the first check valve 14 to the pressure fluctuation of the pressure chamber 16 is high, and it is possible to effectively enhance the followability of the plunger 10 to the tension fluctuation of the chain 6 (see FIG. 1).

Further, as shown in FIG. 3, the chain tensioner 1 holds the second valve body 47 in the valve closed position by the urging force of the second valve spring 49, so that the pressure chamber 16 is held when the engine is stopped. Even when the oil level of the oil inside is once lowered, it is possible to prevent the oil from flowing out from the second reservoir chamber 18 to the pressure chamber 16, and it is possible to retain the oil in the second reservoir chamber 18. Is. Therefore, immediately after starting the engine, oil can be introduced from the second reservoir chamber 18 through the second check valve 17 into the pressure chamber 16 to reliably generate a damper force.

Further, as shown in FIG. 3, the chain tensioner 1 sets the axial movement stroke S2 between the valve closing position and the valve opening position of the _second valve body 47 to close the first valve body 37. Since it is set to be larger _than the axial movement stroke S1 between the valve position and the valve opening position, the pressure from the second reservoir chamber 18 when the second valve body 47 moves to the valve opening position. The flow rate of oil flowing into the chamber 16 is large. Therefore, it is possible to generate a damper force particularly quickly immediately after starting the engine.

Further, even when the axial position of the plunger 10 with respect to the cylinder 9 shown in FIG. 2 changes, the chain tensioner 1 communicates between the cylinder side oil passage 31 and the plunger side oil passage 32 via the enlarged gap portion 27. It is possible to maintain communication. Further, the oil leaking from the pressure chamber 16 through the first gap 26 (leak gap) between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9 can be returned to the refueling passage 30 (enlarged gap portion 27). It is possible.

Further, as shown in FIG. 2, the chain tensioner 1 has a first large-diameter outer diameter surface 23 on the outer periphery of the plunger 10 from a side near the insertion end of the plunger 10 into the cylinder 9 toward a side far from the insertion end. The small diameter outer diameter surface 24 and the second large diameter outer diameter surface 25 are formed in this order, and the first gap 26 formed between the first large diameter outer diameter surface 23 and the inner circumference of the cylinder 9 leaks. Since the gap is used, even when the plunger 10 moves in the axial direction with respect to the cylinder 9, the axial length of the first gap 26 (leak gap) does not change and becomes constant, and a damper force having a stable size is provided. It is possible to obtain.

FIG. 7 shows the chain tensioner 1 according to the second embodiment of the present invention. The parts corresponding to the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

On the inner circumference of the cylinder 9, the first small diameter inner diameter surface 70, the large diameter inner diameter surface 71, and the second Small diameter inner diameter surface 72 is formed. The first small diameter inner diameter surface 70 and the second small diameter inner diameter surface 72 are cylindrical inner diameter surfaces having the same inner diameter dimension. That is, the first small diameter inner diameter surface 70 and the second small diameter inner diameter surface 72 are cylindrical surfaces processed in the same process. The outer circumference of the plunger 10 is a cylindrical surface having a constant outer diameter along the axial direction.

A leak gap 26 is formed between the first small diameter inner diameter surface 70 and the outer periphery of the plunger 10. The oil supply passage 30 is formed in the cylinder 9 so as to introduce oil supplied from the outside of the cylinder 9 into the enlarged gap 27 between the large diameter inner diameter surface 71 on the inner circumference of the cylinder 9 and the outer periphery of the plunger 10. It is composed of a cylinder-side oil passage 31, an enlarged gap portion 27, and a plunger-side oil passage 32 formed in the plunger 10 so as to communicate between the expanded gap portion 27 and the first reservoir chamber 15.

FIG. 8 shows the chain tensioner 1 according to the third embodiment of the present invention. The parts corresponding to the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The air bleeding passage 19 is a pore formed from the outside of the cylinder 9 through the second reservoir chamber 18. The end of the air bleeding passage 19 on the side of the second reservoir chamber 18 is the upper portion of the end of the second reservoir 18 on the side far from the protruding end of the plunger 10 from the cylinder 9 (left side in the figure). Communicate with.

FIG. 9 shows the chain tensioner 1 according to the fourth embodiment of the present invention. The parts corresponding to the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

An annular seal groove 74 is formed on the inner circumference of the cylinder 9 at a portion closer to the protruding end of the plunger 10 from the cylinder 9 than the first gap 26 (leak gap). The seal groove 74 incorporates a seal member 75 that is in sliding contact with the outer periphery of the plunger 10. The seal member 75 is a rubber member (for example, an O-ring) formed in an annular shape. By doing so, it becomes possible to suppress the oil consumption in the chain tensioner extremely effectively.

The seal groove 74 may be provided on the outer circumference of the plunger 10 instead of the inner circumference of the cylinder 9 among the inner circumference of the cylinder 9 and the outer circumference of the plunger 10. That is, on the outer peripheral portion of the plunger 10, the portion closer to the protruding end from the cylinder 9 of the plunger 10 than the first gap 26 (leak gap) (for example, the small diameter outer diameter surface 24 of the second large diameter outer diameter surface 25). A seal member 75 that is in sliding contact with the inner circumference of the cylinder 9 may be incorporated into the seal groove 74 formed at the end portion on the near side).

In each of the above embodiments, in order to form the orifice passage 56, a groove 63 is formed in the mating surface 62 of the orifice seat 55 with respect to the second valve seat 45, but as shown in FIG. 11, the cylinder 9 of the orifice seat 55 is formed. A groove 63 may be formed on the mating surface 76. Further, as shown in FIG. 12, the groove 63 may be formed directly on the mating surface 77 of the second valve seat 45 with respect to the cylinder 9 without providing the orifice seat 55. Further, as shown in FIG. 13, the groove 63 may be formed on the mating surface 78 of the cylinder 9 with respect to the second valve seat 45 without providing the orifice seat 55.

In each of the above embodiments, an example in which the chain tensioner 1 is incorporated in a chain transmission device that transmits the rotation of the crankshaft 2 to the camshaft 4 has been described. However, the chain tensioner 1 uses an oil pump for the rotation of the crankshaft 2. For chain transmission devices that transmit to auxiliary equipment such as water pumps and superchargers, chain transmission devices that transmit the rotation of the crankshaft 2 to the balancer shaft, and chain transmission devices that connect the intake cam and exhaust cam of a twin cam engine to each other. It is also possible to incorporate it.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Chain tensioner 9 Cylinder 10 Plunger 14 First check valve 15 First reservoir chamber 16 Pressure chamber 17 Second check valve 18 Second reservoir chamber 19 Air bleeding passage 20 Screw hole 21 Male thread member 22 Return spring 23 First Large diameter outer diameter surface 24 Small diameter outer diameter surface 25 Second large diameter outer diameter surface 26 First gap (leak gap)
27 Enlarged gap 28 Second gap 30 Refueling passage 31 Cylinder side oil passage 32 Plunger side oil passage 35 First valve seat 36 First valve hole 37 First valve body 45 Second valve seat 46 Second Valve hole 47 Second valve body 49 Second valve spring 56 orifice passage 74 Seal groove 75 Seal member S ₁ , S ₂ Moving stroke

Claims (11)

A cylindrical cylinder (9) with one end in the axial direction as the closed end and the other end in the axial direction as the open end.
With a tubular plunger (10) that is slidably inserted into the cylinder (9) in the axial direction, the insertion end into the cylinder (9) is opened, and the protruding end from the cylinder (9) is closed. ,
A return spring (22) that urges the plunger (10) in a direction protruding from the cylinder (9), and a return spring (22).
A space surrounded by the cylinder (9) and the plunger (10), which is fixedly provided on the inner circumference of the plunger (10) so as to move in the axial direction integrally with the plunger (10), is formed in the plunger (10). The first reservoir chamber (15) on the side close to the protruding end from the cylinder (9) of the plunger (10) and the pressure chamber (16) on the side far from the protruding end from the cylinder (9) of the plunger (10). A first check valve (14) that is axially partitioned and allows only oil to move from the side of the first reservoir chamber (15) to the side of the pressure chamber (16).
An oil supply passage (30) for introducing oil supplied from the outside of the cylinder (9) into the first reservoir chamber (15), and
Formed between the outer circumference of the plunger (10) and the inner circumference of the cylinder (9), from the pressure chamber (16) when the plunger (10) moves in the direction of being pushed into the cylinder (9). Has a leak gap, which allows oil to leak,
The oil supply passage (30) is provided in connection with the outlet side end of the leak gap so as to return the oil leaked from the pressure chamber (16) through the leak gap to the oil supply passage (30). In the chain tensioner
A second check valve (17) arranged at the axial end of the pressure chamber (16) on the side far from the protruding end of the plunger (10) from the cylinder (9).
A second reservoir chamber (18) communicating with the pressure chamber (16) via the second check valve (17) is provided.
The second check valve (17) is configured to allow only the movement of oil from the side of the second reservoir chamber (18) to the side of the pressure chamber (16).
A chain tensioner characterized in that an orifice passage (56) communicating between the second reservoir chamber (18) and the pressure chamber (16) is provided in parallel with the second check valve (17). .. The chain tensioner according to claim 1, wherein an air bleeding passage (19) for communicating the second reservoir chamber (18) with the outside of the cylinder (9) is provided. The air bleeding passage (19) has a screw hole (20) formed through the second reservoir chamber (18) from the outside of the cylinder (9) and a male screw member screwed into the screw hole (20). The chain tensioner according to claim 2, which is a spiral screw gap formed between the chain tensioner and the screw gap (21). The chain tensioner according to claim 2, wherein the air bleeding passage (19) is a pore formed through the outside of the cylinder (9) through the second reservoir chamber (18). The first check valve (14) is formed by axially penetrating the first valve seat (35) fixed to the inner circumference of the plunger (10) and the first valve seat (35). The first valve hole (36), the valve closing position for closing the first valve hole (36), and the protruding end of the plunger (10) from the cylinder (9) with respect to the valve closing position. The chain tensioner according to any one of claims 1 to 4, wherein the chain tensioner has a first valve body (37) provided so as to be movable in the axial direction with and from a valve opening position moved in the axial direction on the distant side. The first check valve (14) has the first valve body (37) in the first valve body (37) when the first valve body (37) is in the closed position. The chain tensioner according to claim 5, wherein only gravity due to its own weight and pressure of oil act. The second check valve (17) is formed by axially penetrating a second valve seat (45) fixed to the inner circumference of the cylinder (9) and the second valve seat (45). The second valve hole (46), the valve closing position for closing the second valve hole (46), and the protruding end of the plunger (10) from the cylinder (9) with respect to the valve closing position. A second valve body (47) provided so as to be movable in the axial direction between the valve opening position moved in the axial direction on the approaching side and the second valve body (47) are attached to the plunger (10). With a second valve spring (49) urging in the axial direction on the side away from the protruding end from the cylinder (9) of the cylinder (9), when the second valve body (47) is in the valve closed position. The chain tensioner according to claim 5 or 6, wherein the urging force of the second valve spring (49) acts on the second valve body (47). The axial movement stroke (S ₂ ) between the valve closing position and the valve opening position of the second valve body (47) is the valve closing position and the valve opening position of the first valve body (37). The chain tensioner according to claim 7, which is set to be larger _than the axial movement stroke (S1) between. A seal groove (1) formed in one of the inner circumference of the cylinder (9) and the outer circumference of the plunger (10) closer to the protruding end of the plunger (10) from the cylinder (9) than the leak gap. The chain tensioner according to any one of claims 1 to 8, wherein a seal member (75) that is in sliding contact with the other is incorporated in 74). The leak gap is the annular gap between the outer circumference of the plunger (10) and the inner circumference of the cylinder (9), which is closer to the insertion end of the plunger (10) into the cylinder (9). A first gap (26) formed at the end,
Of the annular gap between the outer circumference of the plunger (10) and the inner circumference of the cylinder (9), the plunger (10) is inserted into the cylinder (9) with respect to the first gap (26). An enlarged gap portion (27) formed in a portion far from the insertion end and having a gap size larger than that of the first gap (26).
Insertion of the plunger (10) into the cylinder (9) with respect to the enlarged gap (27) in the annular gap between the outer circumference of the plunger (10) and the inner circumference of the cylinder (9). It further has a second gap (28) formed in a portion far from the end and having a gap size smaller than that of the enlarged gap (27).
The oil supply passage (30) has a cylinder-side oil passage (31) formed in the cylinder (9) so as to introduce oil supplied from the outside of the cylinder (9) into the enlarged gap portion (27). , The expanded gap (27), the expanded gap (27), and the first reservoir chamber (15) are formed so as to communicate with each other from the outer periphery to the inner circumference of the plunger (10). The chain tensioner according to any one of claims 1 to 9, which is composed of an oil passage (32) on the plunger side. A cylindrical first large-diameter outer diameter surface (23) is formed at the end of the outer periphery of the plunger (10) on the side close to the insertion end of the plunger (10) into the cylinder (9). ,
The portion of the outer periphery of the plunger (10) on the side far from the insertion end of the plunger (10) into the cylinder (9) with respect to the first large-diameter outer diameter surface (23). A small diameter outer diameter surface (24) having an outer diameter dimension smaller than that of the first large diameter outer diameter surface (23) is formed.
The first large diameter of the outer periphery of the plunger (10) is located on the portion of the outer circumference of the plunger (10) far from the insertion end of the plunger (10) into the cylinder (9) with respect to the small diameter outer diameter surface (24). A second large-diameter outer diameter surface (25) having the same outer diameter dimension as the outer diameter surface (23) is formed.
The first gap (26) is a gap formed between the first large-diameter outer diameter surface (23) and the inner circumference of the cylinder (9).
The enlarged gap portion (27) is a gap formed between the small diameter outer diameter surface (24) and the inner circumference of the cylinder (9).
The chain tensioner according to claim 10, wherein the second gap (28) is a gap formed between the second large-diameter outer diameter surface (25) and the inner circumference of the cylinder (9).

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