WO2020189403A1

WO2020189403A1 - Chain tensioner

Info

Publication number: WO2020189403A1
Application number: PCT/JP2020/010249
Authority: WO
Inventors: 好一鬼丸
Original assignee: Ntn株式会社
Priority date: 2019-03-18
Filing date: 2020-03-10
Publication date: 2020-09-24
Also published as: JP7262256B2; JP2020153383A

Abstract

A chain tensioner that comprises a cylindrical plunger (10) that is slidably supported in a cylinder (9), a return spring (33) that urges the plunger (10) in the direction in which the plunger (10) protrudes from one end of the cylinder (9), a check valve (20) that is arranged between the plunger (10) and a pressure chamber (18) that is formed inside the cylinder (9), an oil supply passage (31) that connects the inside and the outside of the cylinder (9), and an auxiliary spring (34) that has less elastic force than the return spring (33) and urges the plunger (10) in the direction in which the plunger (10) protrudes from the one end of the cylinder (9).

Description

Chain tensioner

The present invention relates to a chain tensioner used to maintain tension in a chain.

Chain transmission devices used in engines such as automobiles include, for example, a device that transmits the rotation of a crankshaft to a camshaft, a device that transmits the rotation of a crankshaft to an auxiliary machine such as an oil pump, and a device that transmits the rotation of a crankshaft. There are those that transmit to the balancer shaft, and those that connect the intake cam and exhaust cam of a twin cam engine to each other. Chain tensioners are used to keep the chain tension in these chain transmissions within the proper range.

The chain tensioner generally generates a hydraulic damper by supplying oil from the engine to keep the fluctuation of the tension of the chain constant. However, since the oil supply is stopped when the engine is stopped, it may not be possible to generate a predetermined hydraulic damper after the engine is started until the pressure chamber inside the chain tensioner is filled with oil. In such a case, there is a problem that the chain tensioner is pushed in greatly and the chain flutters or makes an abnormal noise. Therefore, many chain tensioners are equipped with a mechanism called a no-back mechanism to prevent the plunger from being pushed in more than a certain amount.

In addition, by circulating the oil inside the chain tensioner, the outflow of oil to the outside of the chain tensioner is suppressed, and by storing the oil inside the chain tensioner, a hydraulic damper can be generated immediately after the engine is started. There is also a chain tensioner (see, for example, Patent Documents 1 and 2).

For example, the chain tensioner 50 shown in FIG. 6 has a tubular cylinder 9 having one end open and the other end closed, and a tubular plunger 10 slidably supported by the inner circumference of the cylinder 9 in the axial direction. A return spring 33 for urging the plunger 10 in a direction protruding from the cylinder 9 toward one end, a reservoir chamber 27 formed inside the plunger 10, and the other end side of the plunger 10 in the cylinder 9. A pressure chamber 18 whose volume changes with the axial movement of the plunger 10 and a check valve 20 provided at the insertion end of the plunger 10 into the cylinder 9 to allow only the flow of oil from the reservoir chamber 27 to the pressure chamber 18. And have.

The cylinder 9 has an oil supply passage 31 for introducing oil supplied by an engine oil pump or the like inside, and the oil supply passage 31 is formed between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9. It is open to the supply space 28. A leak gap 19 is formed between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9. The leak gap 19 is composed of a minute gap, and reaches the opening at one end of the cylinder 9 from the pressure chamber 18 through the oil supply space 28. Further, the leak gap 19, the oil supply space 28, and the reservoir chamber 27 are communicated with each other by a connecting passage 30. Further, in order to make the plunger 10 follow the fluttering of the chain, a return spring 33 for applying thrust to the plunger 10 is provided.

When the tension of the chain increases while the engine is operating, the tension of the chain moves the plunger 10 in the direction of being pushed toward the other end side in the cylinder 9 (hereinafter referred to as "pushing direction") to absorb the tension of the chain. To do. At this time, the check valve 20 is closed due to the pressure increase on the pressure chamber 18 side, and the oil flows out from the pressure chamber 18 to the oil supply space 28 side through the leak gap 19. A damper force is generated by the viscous resistance of the oil passing through the leak gap 19 to prevent the chain from fluttering. At this time, a part of the oil flows out of the chain tensioner 50 through the leak gap 19 on one end side of the oil supply space 28 and returns to the engine side. However, since the leak gap 19 is a minute gap and the resistance of the flow path is large, most of the oil is returned from the oil supply space 28 to the reservoir chamber 27 through the communication passage 30.

On the other hand, when the tension of the chain decreases during engine operation, the urging force of the return spring 33 causes the plunger 10 to move in the direction of projecting from the cylinder 9 toward one end (hereinafter referred to as "projecting direction"), resulting in slackening of the chain. To absorb. At this time, the check valve 20 opens and oil flows from the reservoir chamber 27 into the pressure chamber 18, so that the plunger 10 quickly moves in the protruding direction.

Special Fair 3-010819 Gazette Japanese Unexamined Patent Publication No. 2015-183767

In the conventional chain tensioner 50 shown in FIG. 6, the hydraulic damper force is generated by the oil stored inside the tensioner immediately after the engine is started until the oil is supplied to the tensioner. Therefore, it is advantageous that the amount of stored oil increases when the space volume inside the plunger 10 is large. However, in order to increase the internal space volume of the plunger 10, it is necessary to increase the size (length and diameter) of the plunger 10, which causes a problem that the tensioner becomes large and the weight increases.

Further, as a means for compensating for the insufficient thrust of the plunger 10, a method of strengthening the elastic force of the return spring 33 is known. However, when the size of the tensioner is the same as that of the conventional one, there is a space limitation on the wire diameter and the number of turns of the return spring 33 that can be incorporated inside. Therefore, there is a limit to increasing the thrust applied to the plunger 10 by strengthening the return spring 33. As a result, if the thrust by the spring is insufficient with respect to the mass of the plunger and the usage conditions (acceleration), the plunger may not follow properly, which may lead to fluttering of the chain and generation of abnormal noise.

Therefore, the problem to be solved by this invention is to make a chain tensioner that generates an appropriate thrust by following a change in tension or fluttering of the chain.

In order to solve the above problems, the present invention presents a tubular cylinder having one end open and the other end closed, and an opening end that is slidably supported in the axial direction on the inner circumference of the cylinder and is inserted into the cylinder. A tubular plunger whose protruding end from the cylinder is closed, a return spring that urges the plunger in a direction protruding from one end of the cylinder, and a volume that changes with the axial movement of the plunger. A pressure chamber formed in the cylinder, a check valve that allows only the flow of oil from the inside of the plunger to the pressure chamber, an oil supply passage that introduces oil from the outside to the inside of the cylinder, and the return spring. A chain tensioner having an auxiliary spring having a smaller elastic force and urging the plunger in a direction protruding from one end of the cylinder was adopted.

Here, the return spring and the auxiliary spring are coil springs, and the auxiliary spring can adopt a configuration in which the coil diameter is larger than that of the return spring and is arranged coaxially with the return spring. ..

Further, the return spring and the auxiliary spring can adopt a configuration in which the winding directions of the coil springs are opposite to each other.

In each of these aspects, the check valve comprises a valve seat addressed to the end face of the plunger facing the other end, a valve hole formed in the valve seat, and a valve body that opens and closes the valve hole. The return spring can adopt a configuration in which the valve seat is pressed toward the end face side.

Further, the return spring can adopt a structure having a tapered shape in which the end face side has a small diameter.

In each of these embodiments, the total thrust (unit: N) of the return spring and the auxiliary spring within the stroke range of the plunger is 0.8 times or more the numerical value of the mass (unit: g) of the plunger. The set configuration can be adopted.

The present invention can be a chain tensioner that generates an appropriate thrust by following a change in tension or fluttering of the chain.

Overall view which shows the chain transmission device which incorporated the chain tensioner of embodiment of this invention. Right side view of the chain tensioner in FIG. Rear view of FIG. 2A Longitudinal sectional view showing a chain tensioner according to an embodiment of the present invention. Enlarged view of the main part of FIG. Graph diagram schematically showing the characteristics of the chain tensioner according to the embodiment of the present invention. Longitudinal section showing a conventional chain tensioner

FIG. 1 shows a chain transmission device incorporating the chain tensioner 1 according to the 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 each of the two camshafts 4 are connected via a chain 6, and the chain 6 is connected to the crankshaft. The rotation of 2 is transmitted to the camshaft 4, and the rotation of the camshaft 4 opens and closes the valve of the combustion chamber.

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

As shown in FIGS. 2A, 2B and 3, the chain tensioner 1 is supported by a cylindrical cylinder 9 having one end open and the other end closed so as to be slidable in the axial direction on the inner circumference of the cylinder 9. It is equipped with a cylinder 10. The protruding end 17 of the plunger 10 protruding from one end of 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 is fixed to an engine wall surface such as a cylinder block by tightening bolts 12 inserted into holes 11a (see FIG. 2B) of a plurality of mounting pieces 11 integrally formed on the outer periphery of the cylinder 9. .. Further, the cylinder 9 is attached to the engine wall surface so that the projecting direction of the plunger 10 from the cylinder 9 is obliquely upward.

The plunger 10 is formed in a tubular shape in which the insertion end into the cylinder 9 at the other end is open and the protruding end 17 from the cylinder 9 at one end 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)).

At the other end of the cylinder 9, a pressure chamber 18 whose volume changes with the axial movement of the plunger 10 is formed. The volume of the pressure chamber 18 increases when the plunger 10 moves in the protruding direction, and decreases when the plunger 10 moves in the pushing direction.

A check valve that allows only the flow of oil from the inside of the plunger 10 to the pressure chamber 18 side at the insertion end of the plunger 10 into the cylinder 9 and regulates the flow of oil from the pressure chamber 18 to the inside of the plunger 10. 20 is provided. The check valve 20 has a valve seat 21 provided at the insertion end of the plunger 10 into the cylinder 9, a valve hole 21a provided in the valve seat 21, and a spherical shape that opens and closes the valve hole 21a from the pressure chamber 18 side. It is composed of a check ball (hereinafter referred to as a check ball 25) which is a valve body 25 of the above, and a retainer 26 which regulates a moving range of the check ball 25. The retainer 26 includes a holding portion 26a that prevents the check ball 25 from detaching toward the pressure chamber 18, and a hem portion 26b that supports the holding portion 26a on the valve seat 21. The radial holding portion 26a rising from the hem portion 26b toward the pressure chamber 18 side is fitted into a cylindrical protrusion around the valve hole 21a of the valve seat 21.

Here, the inside of the plunger 10 is a reservoir chamber 27 having a diameter larger than the diameter of the valve hole 21a of the check valve 20. The valve seat 21 of the check valve 20 is attached to the other end of the reservoir chamber 27. The valve seat 21 has a cylindrical or disk shape, and the valve hole 21a is formed so as to penetrate one end side and the other end side of the axis of the valve seat 21. When the valve body 25 is separated from the valve hole 21a to the other end side, the pressure chamber 18 and the reservoir chamber 27 communicate with each other through the valve hole 21a.

As shown in FIG. 3, a leak gap 19 for leaking oil from the inside of the pressure chamber 18 to the outside of the pressure chamber 18 is provided between the outer circumference 15 of the plunger 10 and the inner circumference 14 of the cylinder 9. The size of the leak gap 19 can be set in the range of 0.005 to 0.100 mm, for example, by the radius difference between the outer circumference 15 of the plunger 10 and the inner circumference 14 of the cylinder 9.

Further, an oil supply space 28 communicating with the leak gap 19 is formed between the outer circumference 15 of the plunger 10 and the inner circumference 14 of the cylinder 9. The oil supply space 28 is formed in an annular shape between the recess 16 formed on the entire outer circumference of the plunger 10 and the inner circumference 14 of the cylinder 9. The recess 16 for forming the oil supply space 28 is provided in a range where the plunger 10 communicates with the oil supply passage 31 even when the plunger 10 moves in the protruding direction and the pushing direction, respectively, and one end side and the other end thereof sandwich the recess 16. There are leak gaps 19 on each side.

As shown in FIGS. 3 and 4, a return spring 33 is incorporated in the pressure chamber 18. The other end 33b of the return spring 33 is supported by the bottom 13 of the cylinder 9, and one end 33a presses the plunger 10 and urges the plunger 10 in the protruding direction by the pressing.

Further, the pressure chamber 18 incorporates an auxiliary spring 34 having an elastic force smaller than that of the return spring 33. Similarly, the other end 34b of the auxiliary spring 34 is supported by the bottom portion 13 of the cylinder 9, one end 34a presses the plunger 10, and the pressing forcees the plunger 10 in the projecting direction.

As shown in FIGS. 3 and 4, the return spring 33 and the auxiliary spring 34 are both composed of a coil spring in which a wire rod is spirally wound. The outer diameter of the auxiliary spring 34 is larger than the outer diameter of the return spring 33, and the auxiliary spring 34 is arranged on the outer diameter side of the return spring 33. Further, the auxiliary spring 34 and the return spring 33 are arranged coaxially so that the axis of the auxiliary spring 34 coincides with the axis of the return spring 33.

The plunger 10 is provided with a connecting passage 30 that communicates between the oil supply space 28 and the reservoir chamber 27. The communication passage 30 also communicates with the leak gap 19 through the oil supply space 28.

The communication passage 30 is provided so as to be located on the upper half circumference of the plunger 10 with the mounting piece 11 of the cylinder 9 fixed to the engine wall surface. Specifically, the communication passage 30 is provided in the radial upper portion of the plunger 10 and within a range corresponding to half of the outer peripheral dimension of the plunger 10. In particular, in this embodiment, the communication passage 30 is a plunger. It is provided so as to be located at the top of the outer circumference of 10. Therefore, when air is present inside the reservoir chamber 27, the air can be smoothly discharged from the communication passage 30.

Further, as shown in FIG. 3, the cylinder 9 is provided with a refueling passage 31 for introducing oil from the outside to the inside of the cylinder 9. The refueling passage 31 is a through hole that penetrates the cylinder 9 in the radial direction. The inlet of the refueling passage 31 (see FIG. 2B) is connected to the oil supply port on the wall surface side of the engine. The outlet of the oil supply passage 31 opens to the cylindrical surface on the inner circumference of the cylinder 9 and faces the oil supply space 28. The oil supplied from the oil pump of the engine is introduced from the outside to the inside of the cylinder 9 through the oil supply passage 31.

An operation example of this chain tensioner 1 will be described. During normal operation, when the tension of the chain 6 becomes larger than the thrust of the return spring 33 that urges the plunger 10, the tension of the chain 6 causes the plunger 10 to move in the pushing direction into the cylinder 9, and the tension of the chain 6 is increased. To absorb. Then, the valve seat 21 moves to the pressure chamber 18 side together with the plunger 10. Since the volume of the pressure chamber 18 is reduced according to the movement of the plunger 10 and the valve seat 21, the pressure of the pressure chamber 18 becomes higher than the pressure of the reservoir chamber 27, and the check valve 20 is closed to seal the pressure chamber 18. At this time, most of the oil flowing out from the pressure chamber 18 through the leak gap 19 returns to the reservoir chamber 27 through the oil supply space 28 and the communication passage 30. A damper force is generated by the viscous resistance of the oil flowing through the leak gap 19, and the chain 6 is prevented from fluttering.

Further, when the tension of the chain 6 becomes small during engine operation, the plunger 10 moves in the protruding direction by the urging force of the return spring 33 and the auxiliary spring 34 to absorb the slack of the chain 6. At this time, since the volume of the pressure chamber 18 expands according to the movement of the plunger 10, the pressure in the pressure chamber 18 becomes lower than the pressure in the reservoir chamber 27, and the check valve 20 opens. Then, since oil flows from the reservoir chamber 27 into the pressure chamber 18 through the valve hole 21a of the check valve 20, the plunger 10 moves quickly. At this time, the pressure of the oil pump introduces oil from the outside of the cylinder 9 into the reservoir chamber 27 through the oil supply passage 31, the oil supply space 28, and the communication passage 30. Therefore, the pressure drop in the reservoir chamber 27 is unlikely to occur, and the chain 6 has excellent followability to slack.

Further, since the chain tensioner 1 has a reservoir chamber 27 having a diameter larger than the diameter of the valve hole 21a of the check valve 20 formed inside the plunger 10, a large amount of oil is stored inside the plunger 10. Can be secured. Therefore, even when the oil is not supplied from the engine to the chain tensioner 1 immediately after the engine is started, the damper force can be generated by using the oil stored in the reservoir chamber 27.

Here, the return spring 33 is required to have a sufficient thrust (elastic force) to press the plunger 10 in the protruding direction in order to absorb the slack of the chain 6. However, if the return spring 33 that generates a large thrust is adopted, the diameter (outer diameter) and the length (total length) of the return spring 33 become large, so that the space in the pressure chamber 18 also needs to be large. Therefore, there is a problem that the size of the entire tensioner becomes large. Therefore, in the present invention, in order to obtain the necessary thrust of the plunger 10 without increasing the size of the entire tensioner, two coil springs that give the thrust to the plunger 10 are adopted. That is, as a coil spring that applies thrust to the plunger 10, in addition to the return spring 33, an auxiliary spring 34 having a coil outer diameter different from that of the return spring 33 is arranged.

When thrust is applied to the plunger 10 only by the return spring 33 as in the conventional case, the thrust required to eliminate the slack of the chain 6 is obtained depending on the stroke position (use position during operation) of the plunger 10. It may not be possible. However, by arranging the auxiliary spring 34 in addition to the return spring 33, it is possible to secure the required thrust over the entire stroke of the plunger 10.

Here, in this embodiment, as shown in FIG. 4, the valve seat 21 of the check valve 20 is not press-fitted and fixed to the plunger 10, and the valve seat 21 is an end face facing the other end side of the plunger 10. It is addressed to 10a. Further, one end 34a of the auxiliary spring 34 directly contacts the end surface 10b of the portion closer to the outer diameter of the plunger 10 and presses the plunger 10 in the projecting direction. Further, the return spring 33 abuts on the hem portion 26b of the retainer 26 which is in contact with the end surface 21b of the valve seat 21 and presses the plunger 10 in the projecting direction via the valve seat 21.

Therefore, if the thrust applied to the plunger 10 by the elastic force of the auxiliary spring 34 is too strong, the valve seat 21 of the check valve 20 and the plunger 10 may separate from each other. If the check valve 20 separates from the plunger 10 when the plunger 10 protrudes, the hydraulic damper may not operate normally. Therefore, in the present invention, when the auxiliary spring 34 is added, the thrust of the auxiliary spring 34 to the plunger 10 is set so as not to exceed the thrust of the return spring 33 in the stroke range of the plunger 10 in the state of using the chain tensioner 1. are doing. This prevents the valve seat 21 from separating from the plunger 10.

Further, the total thrust (unit: N / Newton) of the return spring 33 and the auxiliary spring 34 within the stroke range of the plunger 10 is 0.8 times or more the value of the mass (unit: g / gram) of the plunger 10. By setting so as to be, the tracking failure of the plunger 10 occurs under normal usage conditions (for example, a 4-cylinder engine, a rotation speed of the crankshaft 2 of the engine of 8000 rpm, and an acceleration of 86 G at a total mass of 0.6 mm of the plunger 10). It is possible to provide stable damper characteristics. For example, when the mass of the plunger 10 is 30 g, it is desirable that the total thrust applied to the plunger 10 is 30 × 0.8 = 24 N or more over the entire stroke of the plunger 10.

FIG. 5 is a graph showing the relationship between the stroke amount of the plunger 10 and the thrust applied to the plunger 10. Reference numeral A in the figure indicates the thrust of the return spring 33 with respect to the plunger 10. Reference numeral B indicates the thrust of the auxiliary spring 34 with respect to the plunger 10. Reference numeral C indicates the thrust required to be applied to the plunger 10. The thrust B of the auxiliary spring 34 has a value smaller than the thrust A of the return spring 33 over the entire stroke range of the plunger 10. The total thrust A + B of the return spring 33 and the auxiliary spring 34 is set to be equal to or greater than the required thrust C of the plunger 10 over the entire stroke range of the plunger 10.

Further, as shown in FIG. 4, the return spring 33 and the auxiliary spring 34 have the spiral winding directions of the coil springs opposite to each other. That is, when the winding direction of the spiral of the return spring 33 is one direction around the axis from one end 33a to the other end 33b, the winding direction of the spiral of the auxiliary spring 34 is the axis from one end 34a to the other end 34b. It is in the other direction. In this way, by reversing the winding directions of the coil springs of the return spring 33 and the auxiliary spring 34, the springs are prevented from interfering with each other. Further, in particular, even when the body bending of the spring is large when the spring is compressed, contact between the two can be prevented and a stable thrust can be obtained.

Further, in this embodiment, the auxiliary spring 34 is a coil spring having a constant outer diameter over the entire length, whereas the return spring 33 has one end 33a facing the end face 10a side and the other end facing the bottom 13 side. It is composed of a tapered coil spring having a diameter smaller than 33b. Further, the hem portion 26b of the retainer 26 is located around the valve hole 21a of the valve seat 21 and is located relatively closer to the inner diameter. Therefore, one end 33a on the small diameter side of the return spring 33 easily presses the hem portion 26b of the retainer 26, and the retainer 26 is easily held by the valve seat 21. Further, by fitting one end 33a on the small diameter side of the return spring 33 into the outer circumference of the radial holding portion 26a rising from the hem portion 26b of the retainer 26 toward the pressure chamber 18, the one end 33a is fixed to the retainer 26 and the valve seat 21. Therefore, the effect of stabilizing the expansion / contraction operation of the return spring 33 can be expected.

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 10a End face 18 Pressure chamber 20 Check valve 21 Valve seat 21a Valve hole 25 Valve body (check ball)
31 Refueling passage 33 Return spring 34 Auxiliary spring

Claims

A tubular cylinder (9) with one end open and the other end closed,
A tubular plunger (10) that is supported so as to be slidable in the axial direction on the inner circumference of the cylinder (9), and the insertion end into the cylinder (9) is opened and the protruding end from the cylinder (9) is closed. And a return spring (33) that urges the plunger (10) in a direction protruding from one end of the cylinder (9).
A pressure chamber (18) formed in the cylinder (9) so that the volume changes with the axial movement of the plunger (10).
A check valve (20) that allows only the flow of oil from the inside of the plunger (10) to the pressure chamber (18).
A refueling passage (31) for introducing oil from the outside to the inside of the cylinder (9),
An auxiliary spring (34) having an elastic force smaller than that of the return spring (33) and urging the plunger (10) in a direction protruding from one end of the cylinder (9).
Chain tensioner with.
The return spring (33) and the auxiliary spring (34) are coil springs, and the auxiliary spring (34) has a coil diameter larger than that of the return spring (33) and is coaxial with the return spring (33). The chain tensioner according to claim 1, which is arranged in.
The chain tensioner according to claim 2, wherein the return spring (33) and the auxiliary spring (34) have coil springs wound in opposite directions to each other.
The check valve (20) includes a valve seat (21) addressed to an end surface (10a) facing the other end side of the plunger (10) and a valve hole (21a) formed in the valve seat (21). A valve body (25) that opens and closes the valve hole (21a).
The chain tensioner according to any one of claims 1 to 3, wherein the return spring (33) presses the valve seat (21) toward the end surface (10a).
The chain tensioner according to claim 4, wherein the return spring (33) has a tapered shape having a small diameter on the end surface (10a) side.
The total thrust (unit: N) of the return spring (33) and the auxiliary spring (34) within the stroke range of the plunger (10) is a numerical value of the mass (unit: g) of the plunger (10). The chain tensioner according to any one of claims 1 to 5, which is set to a numerical value of 8 times or more.