JP2013096432A - Chain tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner for effectively restraining reduction in the damper action just after restarting an engine and dispensing with an assist spring.SOLUTION: This chain tensioner includes a plunger 10 slidably inserted into a cylinder 9, a check valve 13 incorporated into the cylinder 9, a pressure chamber 14 formed between the check valve 13 and the plunger 10, and an oil feeding passage 15 for introducing a hydraulic fluid into the pressure chamber 14 via the check valve 13. The check valve 13 has a valve spring 22 for energizing its valve element 21 toward a valve closing position from a valve opening position. The oil feeding passage 15 is constituted of an oil introducing hole 16 for introducing the hydraulic fluid from an outside of the cylinder 9, and a reservoir chamber 17 adjacently formed on the upstream side of the check valve 13.

Description

  The present invention relates to a chain tensioner used for maintaining tension of a timing chain that drives a camshaft of an automobile engine.

  In general, an engine of an automobile transmits rotation of a crankshaft to a camshaft through a timing chain, and opens and closes a valve of a combustion chamber by the rotation of the camshaft. Here, in order to keep the chain tension within an appropriate range, a tension adjusting device composed of a chain guide provided so as to be able to swing around a fulcrum shaft and a chain tensioner that presses the chain via the chain guide is often used. It is done.

  As a chain tensioner incorporated in this tension adjusting device, the one described in Patent Document 1 is known. As shown in FIGS. 6 and 7, the chain tensioner includes a cylindrical cylinder 50 having one end opened and the other end closed, and a bottomed cylinder inserted into the cylinder 50 so as to be slidable in the axial direction. Formed between the check valve 53 and the plunger 51, a return spring 52 that biases the plunger 51 in a direction protruding from the cylinder 50, a check valve 53 incorporated in the cylinder 50, A pressure chamber 54, and an oil supply passage 55 for introducing hydraulic oil into the pressure chamber 54 via the check valve 53.

  Here, the check valve 53 has a valve body 57 that opens and closes the valve hole of the valve seat 56, but no member that biases the valve body 57 is provided, and the valve body 57 is in a free state in which no external force acts. It has become.

  When the chain tension increases during engine operation, the chain tensioner moves in the direction in which the plunger 51 is pushed into the cylinder 50 (hereinafter referred to as “push-in direction”) due to the chain tension, and absorbs the chain tension. To do. At this time, the hydraulic oil in the pressure chamber 54 flows out through the leak gap 58 between the sliding surface of the plunger 51 and the cylinder 50, and a damper action is generated by the viscous resistance of the hydraulic oil. Moving.

  On the other hand, when the tension of the chain is reduced during the operation of the engine, the biasing force of the return spring 52 moves the plunger 51 in the direction protruding from the cylinder 50 (hereinafter referred to as “protruding direction”) to absorb the slack of the chain. At this time, the check valve 53 is opened and the hydraulic oil flows into the pressure chamber 54 from the oil supply passage 55, so that the plunger 51 moves quickly.

  By the way, when the engine is stopped, the chain tension increases depending on the stop position of the cam, and the pushing force acting on the plunger 51 may increase. In this case, if the plunger 51 moves greatly in the pushing direction, the chain loosens when the engine is restarted, and the loosening causes chain skipping and the engine may not start smoothly.

  Therefore, in order to start the engine smoothly, a sawtooth screw type chain tensioner shown in FIG. 2 of Patent Document 1 and a ring type chain tensioner shown in FIG. 5 of the same document are known.

  As shown in FIG. 6, the sawtooth screw type chain tensioner is provided with a screw rod 61 having a male screw 60 on the outer periphery thereof that engages with a female screw 59 formed on the inner periphery of the plunger 51, and from the plunger 51 of the screw rod 61. The protruding end of this is in contact with the valve seat 56. When the engine is stopped, the tensioner restricts the movement of the plunger 51 in the pushing direction by the engagement of the male screw 60 and the female screw 59. Therefore, when the engine is restarted, the chain is not loosened and the engine can be started smoothly. It is.

  Further, as shown in FIG. 7, the ring-type chain tensioner accommodates a register ring 63 that elastically tightens the outer periphery of the plunger 51 in an annular housing groove 62 formed on the inner periphery of the cylinder 50. The ring 63 is engaged with a circumferential groove 64 formed on the outer periphery of the plunger 51 at a constant interval in the axial direction. In this tensioner, the movement of the plunger 51 in the pushing direction is restricted by the engagement between the register ring 63 and the circumferential groove 64 on the outer periphery of the plunger 51. Therefore, when the engine is restarted, the chain is not loosened smoothly. Engine start is possible.

JP 2010-106877 A

  By the way, depending on the type of engine, each of the sawtooth screw type and ring type chain tensioners may be attached in a posture in which the protruding direction of the plunger 51 from the cylinder 50 is obliquely downward or vertically downward.

  In this case, when the supply of the hydraulic oil to the oil supply passage 55 is stopped by stopping the engine, the hydraulic oil in the oil supply passage 55 passes through the check valve 53 and falls into the pressure chamber 54, and the hydraulic oil enters the oil supply passage 55. Is almost nonexistent. At this time, the hydraulic oil in the pressure chamber 54 flows out through the leak gap 58 between the sliding surfaces of the cylinder 50 and the plunger 51, so that the liquid level of the hydraulic oil in the pressure chamber 54 is lowered. For this reason, when the engine is restarted, the time required for the pressure chamber 54 to be filled with the hydraulic oil is long. During this time, the damper action of the chain tensioner is reduced, and the chain amplitude is increased.

  Therefore, in order to suppress the amplitude of the chain immediately after the engine is restarted, as shown in FIGS. 6 and 7, an assist spring 65 for compensating the urging force of the return spring 52 is provided in the pressure chamber 54. Measures are taken to increase the urging force in the protruding direction acting on the plunger 51.

  However, when the assist spring 65 is provided, the spring force applied to the chain is increased, and there is a problem that the friction loss due to the frictional resistance between the chain and the chain guide increases.

  The problem to be solved by the present invention is to provide a chain tensioner that can effectively suppress a decrease in damper action immediately after the engine is restarted and does not require an assist spring.

  To solve the above problems, a cylindrical cylinder having one end opened and the other end closed, a bottomed cylindrical plunger inserted in the cylinder so as to be slidable in the axial direction, and the plunger A return spring urging in a direction protruding from the cylinder, a check valve built into the cylinder, a pressure chamber formed between the check valve and the plunger, and the pressure chamber via the check valve. In a chain tensioner having an oil supply passage for introducing hydraulic oil, the check valve is formed at a valve seat having a valve hole communicating between the oil supply passage and the pressure chamber, and an end portion of the valve hole on the pressure chamber side. A valve body movably provided between a valve closing position that contacts the seat surface and a valve opening position that is separated from the seat surface, and the valve body is directed from the valve opening position to the valve closing position. The oil supply passage is connected to an oil introduction hole for introducing hydraulic oil from the outside of the cylinder and a downstream side of the oil introduction hole, and is adjacent to the upstream side of the check valve. A configuration comprising a formed reservoir chamber was adopted.

  In this way, since the valve body of the check valve is urged by the valve spring from the open position to the closed position, the check valve is checked when the supply of hydraulic oil to the oil supply passage is stopped due to the engine being stopped. The hydraulic oil in the oil supply passage is held by the valve body of the valve, and the hydraulic oil in the oil supply passage can be prevented from falling into the pressure chamber. Moreover, since the reservoir chamber is formed adjacent to the upstream side of the check valve, when the engine is restarted, the hydraulic oil in the reservoir chamber flows into the pressure chamber, and the pressure chamber is quickly filled with the hydraulic oil. . Therefore, it is possible to effectively suppress the reduction in the damper action immediately after restarting the engine without using the assist spring.

  It is preferable that the inner periphery of the plunger is fitted to the outer periphery of the valve seat so as to be slidable in the axial direction, and a leak gap is formed between the fitting surfaces to allow the hydraulic oil in the pressure chamber to flow out. In this way, since the bottomed cylindrical plunger has a length that reaches the check valve, it is possible to suppress a decrease in the level of the hydraulic oil in the pressure chamber when the oil pump that supplies the hydraulic oil to the oil supply passage is stopped. As a result, it is possible to more effectively suppress a decrease in the damper action immediately after restarting the engine.

  When the inner periphery of the plunger is slidably fitted to the outer periphery of the valve seat and a leak gap is formed between the fitting surfaces, the plunger resistance of the hydraulic oil flowing through the leak gap is set to a predetermined range. The inner circumference needs to be processed with high accuracy. Therefore, it is preferable that the plunger is composed of a cylindrical body having a cylindrical inner peripheral surface that is fitted to the outer periphery of the valve seat, and a cap member that is fitted and fixed to one end of the cylindrical body. In this way, it becomes easy to process the inner periphery of the plunger with high accuracy, and it is possible to obtain a chain tensioner with stable quality while suppressing variations in the radial clearance of the leak gap.

  In this case, the cap member can be fixed to the cylindrical body by welding. However, if the cap member is welded, thermal distortion may occur, and the dimensional accuracy of the inner periphery of the plunger may be lowered. Therefore, the cap member is preferably fixed by press-fitting the cap member into the cylinder. In this way, the dimensional accuracy of the inner periphery of the plunger can be maintained before and after the cap member is fixed, and as a result, the size of the leak gap between the fitting surface of the plunger and the valve seat can be managed with high accuracy. It becomes possible.

  The radial clearance of the leak gap can be set smaller than the radial clearance between the plunger and the sliding surface of the cylinder.

  The reservoir chamber is preferably formed in a cylindrical hole shape extending from the check valve toward the closed end of the cylinder, and the oil introduction hole is connected to the end of the reservoir chamber on the closed end side of the cylinder. In this way, when the chain tensioner is installed in a posture in which the plunger protrudes obliquely downward or vertically downward from the cylinder, the connecting portion of the reservoir chamber and the oil introduction hole comes to the upper portion of the reservoir chamber. When the supply of the working oil to the oil introduction hole is stopped by the stop, it is possible to suppress the backflow of the working oil from the reservoir chamber to the oil introduction hole.

  The reservoir chamber is preferably formed so as to have a volume of 50% or more of the internal volume of the plunger. In this way, it is possible to secure a sufficient amount of hydraulic oil to be stored in the reservoir chamber, and to stably suppress a decrease in the damper action immediately after the engine is restarted.

The present invention can be applied to the following chain tensioner, for example.
1) A screw rod having an external thread that engages with an internal thread formed on the inner periphery of the plunger is provided on the outer periphery, and a protruding end of the screw rod from the plunger is brought into contact with a valve seat provided in the cylinder, The male screw and the female screw have a sawtooth shape in which the flank angle of the pressure side flank that receives pressure when a load in the direction of pushing the plunger into the cylinder is applied is larger than the flank angle of the play side flank. Expression chain tensioner.
2) A register ring that elastically tightens the outer periphery of the plunger is accommodated in an annular accommodating groove formed in the inner periphery of the cylinder, and the register ring is spaced apart from the outer periphery of the plunger at a certain interval in the axial direction. Engage with the formed circumferential grooves, and when a load in the direction in which the plunger protrudes from the cylinder is loaded in each of the circumferential grooves, the diameter of the register ring is expanded to allow the plunger to move. A ring-type chain tensioner provided with a tapered surface and a stopper surface that locks the register ring and restricts the movement of the plunger when a load in a direction of pushing the plunger into the cylinder is applied.

  In the chain tensioner of the present invention, the valve body of the check valve is urged by the valve spring from the valve opening position to the valve closing position, and the reservoir chamber is formed adjacent to the upstream side of the check valve. When the engine is restarted, the hydraulic oil in the reservoir chamber flows into the pressure chamber, and the pressure chamber can be quickly filled with the hydraulic oil. Therefore, it is possible to effectively suppress the reduction in the damper action immediately after restarting the engine without using the assist spring.

The front view which shows the chain transmission apparatus incorporating the chain tensioner of 1st Embodiment of this invention 1 is an enlarged cross-sectional view near the chain tensioner of FIG. The principal part expanded sectional view of the chain tensioner shown in FIG. The expanded sectional view which shows the chain tensioner of 2nd Embodiment of this invention The principal part expanded sectional view of the chain tensioner shown in FIG. Enlarged sectional view showing a conventional chain tensioner Expanded sectional view showing another conventional chain tensioner

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

  The chain 6 is in contact with a chain guide 8 that is swingably supported around the fulcrum shaft 7, and the chain tensioner 1 presses the chain 6 through the chain guide 8.

  As shown in FIG. 2, the chain tensioner 1 includes a cylindrical cylinder 9 that is open at one end and closed at the other end, and a plunger 10 that is slidably inserted in the cylinder 9 in the axial direction. The cylinder 9 is inserted into the tensioner mounting hole 12 of the engine cover 11 with the opening end facing the engine cover 11. A flange portion 9 a is formed integrally with the cylinder 9, and the flange portion 9 a is fixed to the outer surface of the engine cover 11 with bolts. Here, the engine is mounted with an inclination angle when mounted on an automobile or the like (see FIG. 1). In this state of use, in the chain tensioner 1, the protruding direction of the plunger 10 from the cylinder 9 is obliquely downward.

  A check valve 13 is incorporated in the cylinder 9, and a pressure chamber 14 is formed between the check valve 13 and the plunger 10. The cylinder 9 is formed with an oil supply passage 15 through which hydraulic oil is introduced into the pressure chamber 14 via the check valve 13.

  The oil supply passage 15 is connected to an oil introduction hole 16 for introducing hydraulic oil from the outside of the cylinder 9, a reservoir chamber 17 connected to the downstream side of the oil introduction hole 16, and formed adjacent to the upstream side of the check valve 13. Consists of. The oil introduction hole 16 has a diameter extending from the mating surface of the flange portion 9a to the engine cover 11 to the inside of the flange portion 9a and from the outer periphery of the flange portion 9a to the reservoir chamber 17 crossing the axial hole 16A. It consists of direction hole 16B. The axial hole 16 </ b> A communicates with an oil hole 18 that opens on the outer surface of the engine cover 11. Further, the opening on the outer periphery of the flange portion 9 a of the radial hole 16 </ b> B is closed with a male screw component 19. The hydraulic oil supplied from an oil pump (not shown) through the oil hole 18 is introduced into the pressure chamber 14 through the axial hole 16A, the radial hole 16B, the reservoir chamber 17, and the check valve 13 in this order.

  The reservoir chamber 17 is formed in a cylindrical hole shape extending from the check valve 13 toward the closed end of the cylinder 9. A radial hole 16 </ b> B of the oil introduction hole 16 is connected to the end of the reservoir chamber 17 on the closed end side of the cylinder 9. The reservoir chamber 17 is set to a size that can secure at least oil necessary for starting the engine, and takes into account the amount of leakage and layout (size) when starting the engine, and is 50% or more of the internal volume of the plunger 10. It is preferable that it is formed to have a volume.

  As shown in FIG. 3, the check valve 13 includes a valve seat 20, a spherical valve body 21, a valve spring 22, and a retainer 23. The valve seat 20 has a cylindrical shape centered on a valve hole 24 communicating between the oil supply passage 15 and the pressure chamber 14, and is press-fitted into the cylinder 9 and fixed. A tapered seat surface 25 is formed at the end of the valve hole 24 on the pressure chamber 14 side. The valve body 21 is provided so as to be movable between a valve closing position that contacts the seat surface 25 of the valve seat 20 and a valve opening position that is separated from the seat surface 25. It is energized towards. The retainer 23 supports one end of the valve spring 22. This check valve 13 allows the flow of hydraulic oil from the oil supply passage 15 side to the pressure chamber 14 side, but prohibits the flow of hydraulic oil from the pressure chamber 14 side to the oil supply passage 15 side.

  Here, the valve spring 22 is incorporated in a pre-compressed state, so that the weight of the hydraulic oil whose vertical length is the axial length of the reservoir chamber 17 acts on the valve body 21 in the state where the valve oil 21 is applied. A preload having a size capable of holding the closure is applied to the valve body 21 from the valve spring 22.

  The plunger 10 is formed in a bottomed cylindrical shape whose opening end into the cylinder 9 is opened. A cylindrical inner peripheral surface 26 is formed at a portion where the plunger 10 is inserted into the cylinder 9, and the inner peripheral surface 26 is fitted to the cylindrical outer peripheral surface 27 of the valve seat 20 so as to be slidable in the axial direction. ing. The inner peripheral surface 26 is processed so that the surface roughness is Ra 0.8 or less. A minute leak gap 28 is formed between the fitting surfaces of the plunger 10 and the cylinder 9 (that is, between the inner peripheral surface 26 and the outer peripheral surface 27), and pressure is applied when the plunger 10 moves in the direction of being pushed into the cylinder 9. The hydraulic oil in the chamber 14 flows out of the cylinder 9 through the leak gap 28 and between the sliding surfaces of the cylinder 9 and the plunger 10 in order.

  The plunger 10 includes a cylindrical body 10A whose both ends are open and a cap member 10B that is fitted and fixed to one end of the cylindrical body 10A. A cylindrical inner peripheral surface 26 that fits to the outer periphery of the valve seat 20 is formed in the cylindrical body 10A. The cap member 10B can be fixed to the cylindrical body 10A by welding. However, if the cap member 10B is welded, thermal distortion may occur, and the dimensional accuracy of the inner periphery of the plunger 10 may be reduced.

  Therefore, it is preferable to fix the cap member 10B by press-fitting the cap member 10B into the cylindrical body 10A. In this way, the dimensional accuracy of the inner periphery of the plunger 10 can be maintained before and after the cap member 10B is fixed, and as a result, the size of the leak gap 28 between the fitting surface of the plunger 10 and the valve seat 20 is highly accurate. It becomes possible to manage. The radial clearance of the leak gap 28 is set smaller than the radial clearance between the plunger 10 and the sliding surface of the cylinder 9. The cylinder 10A is made of chromium molybdenum steel (so-called SCM material) and is formed by cold forging.

  An internal thread 29 is formed on the inner periphery of the insertion portion of the plunger 10 into the cylinder 9. A screw rod 31 having a male screw 30 that engages with the female screw 29 on the outer periphery is incorporated in the plunger 10. One end of the screw rod 31 protrudes from the plunger 10, and the protruding end is in contact with the valve seat 20 fixed to the cylinder 9. The screw rod 31 is made of chromium molybdenum steel.

  The male screw 30 and the female screw 29 are formed in a sawtooth shape in which the flank angle of the pressure side flank 32 that receives pressure when a load in the direction of pushing the plunger 10 into the cylinder 9 is applied is larger than the flank angle of the play side flank 33. Has been. Such male screw 30 and female screw 29 are, for example, those in which the flank angle of the pressure side flank 32 is 65 °, the flank angle of the play side flank 33 is 7 °, and the flank angle of the pressure side flank 32 is 75 °. The play side flank 33 having a flank angle of 15 ° can be employed. Further, an axial play of 1 mm or more is provided between the male screw 30 and the female screw 29.

  A return spring 34 is incorporated between the plunger 10 and the screw rod 31. One end of the return spring 34 is supported by the screw rod 31, and the other end presses the plunger 10 through the spring seat 35, and the plunger 10 is biased in a direction protruding from the cylinder 9 by the pressing. . The plunger 10 has a protruding end from the cylinder 9 abutting on the chain guide 8 and presses the chain 6 via the chain guide 8.

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

  When the tension of the chain 6 becomes smaller during the operation of the engine, the plunger 10 moves in the protruding direction by the urging force of the return spring 34 and absorbs the slack of the chain 6. At this time, the check valve 13 is opened, and the hydraulic oil supplied from the oil pump flows into the pressure chamber 14 through the oil introduction hole 16 and the reservoir chamber 17, so that the plunger 10 moves quickly.

  On the other hand, when the tension of the chain 6 increases during engine operation, the plunger 10 moves in the pushing direction by the tension of the chain 6 and absorbs the tension of the chain 6. At this time, the screw rod 31 is rotated with respect to the plunger 10 while being repeatedly advanced and retracted within the axial clearance between the female screw 29 and the male screw 30 due to the vibration of the chain 6. Further, since the hydraulic oil in the pressure chamber 14 flows out through the leak gap 28 between the sliding surface of the plunger 10 and the valve seat 20 and a damper action is generated by the viscous resistance of the hydraulic oil, the plunger 10 is slowly Moving.

  When the engine is stopped, the tension of the chain 6 may increase depending on the stop position of the camshaft 4. In this case, since the chain 6 does not vibrate, the internal thread 29 of the plunger 10 is received by the external thread 30 of the screw rod 31. Ten positions are fixed. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  When the engine is stopped, the oil pump that supplies hydraulic oil to the oil supply passage 15 is also stopped. At this time, the hydraulic oil in the reservoir chamber 17 is held by the valve body 21 of the check valve 13, and the hydraulic oil in the reservoir chamber 17 can be prevented from falling into the pressure chamber 14. Therefore, when the engine is restarted, the hydraulic oil in the reservoir chamber 17 flows into the pressure chamber 14, and the pressure chamber 14 is quickly filled with the hydraulic oil. As a result, it is possible to suppress a decrease in the damper action immediately after the engine is restarted.

  Further, since the bottomed cylindrical plunger 10 has a length that reaches the check valve 13, when the oil pump that supplies the operating oil to the oil supply passage 15 stops, the liquid level of the operating oil in the pressure chamber 14 decreases. The amount is reduced. Therefore, when the engine is restarted, only a small amount of hydraulic oil is needed to fill the pressure chamber 14 with the hydraulic oil, and the reduction in the damper action immediately after the engine is restarted can be more effectively suppressed. It is possible.

  As described above, the chain tensioner 1 is configured such that the valve element 21 of the check valve 13 is urged by the valve spring 22 from the valve opening position toward the valve closing position, and the reservoir is adjacent to the upstream side of the check valve 13. Since the chamber 17 is formed, when the engine is restarted, the hydraulic oil in the reservoir chamber 17 flows into the pressure chamber 14, and the pressure chamber 14 can be quickly filled with the hydraulic oil. Therefore, it is possible to effectively suppress the decrease in the damper action immediately after restarting the engine without using the assist spring, and the amplitude of the chain 6 immediately after restarting the engine can be suppressed.

  Further, in this chain tensioner 1, since the cylinder 10 </ b> A and the cap member 10 </ b> B constitute the plunger 10, it is easy to process the inner peripheral surface 26 of the plunger 10 with high accuracy, and the diameter of the leak gap 28. Stable quality can be obtained by suppressing variation in the size of the directional clearance.

  In addition, when the chain tensioner 1 is attached in a posture in which the protruding direction of the plunger 10 from the cylinder 9 is obliquely downward or vertically downward, the connecting portion of the reservoir chamber 17 and the oil introduction hole 16 becomes the reservoir chamber. Therefore, when the supply of the working oil to the oil introduction hole 16 is stopped by stopping the engine, the backflow of the working oil from the reservoir chamber 17 to the oil introduction hole 16 can be suppressed.

  Further, since the chain tensioner 1 forms the reservoir chamber 17 so as to have a volume of 50% or more of the internal volume of the plunger 10, the amount of hydraulic oil stored in the reservoir chamber 17 is secured, and the engine is operated. It is possible to stably suppress a decrease in the damper action immediately after restarting.

  4 and 5 show a chain tensioner 40 according to a second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  An accommodation groove 42 for accommodating the register ring 41 is formed on the inner periphery of the cylinder 9, and the register ring 41 accommodated in the accommodation groove 42 elastically tightens the outer periphery of the plunger 10. A plurality of circumferential grooves 43 are formed on the outer periphery of the plunger 10 at regular intervals in the axial direction, and the register ring 41 is engaged with the circumferential grooves 43.

  In each circumferential groove 43, there is a tapered surface 44 that allows the movement of the plunger 10 by expanding the diameter of the register ring 41 when a load in a direction in which the plunger 10 protrudes from the cylinder 9 is applied, and the plunger 10. A stopper surface 45 is provided that locks the register ring 41 and restricts the movement of the plunger 10 when a load in the direction of pushing into the cylinder 9 is applied.

  In the chain tensioner 40, the register ring 41 moves back and forth in the accommodation groove 42 when the plunger 10 repeats forward and backward movement due to vibration of the chain 6 during engine operation. When the movement range in the protruding direction of the plunger 10 exceeds the movable range in the receiving groove 42 of the register ring 41 due to the slack of the chain 6, the tapered surface 44 in the circumferential groove 43 is moved to the register ring 41. Is expanded to allow the plunger 10 to move. At this time, the register ring 41 engages with the adjacent circumferential groove 43.

  When the tension of the chain 6 is increased due to the stop position of the camshaft 4 when the engine is stopped, the engagement of the register ring 41 and the circumferential groove 43 prevents the plunger 10 from moving in the pushing direction. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  Similarly to the first embodiment, when the oil pump for supplying the hydraulic oil to the oil supply passage 15 stops with the stop of the engine, the hydraulic oil in the reservoir chamber 17 is held by the valve body 21 of the check valve 13. Thus, it is possible to prevent the hydraulic oil in the reservoir chamber 17 from falling into the pressure chamber 14. Therefore, when the engine is restarted, the hydraulic oil in the reservoir chamber 17 flows into the pressure chamber 14, and the pressure chamber 14 is quickly filled with the hydraulic oil. As a result, it is possible to suppress a decrease in the damper action immediately after the engine is restarted.

  Similarly to the first embodiment, since the bottomed cylindrical plunger 10 has a length that reaches the check valve 13, when the oil pump that supplies hydraulic oil to the oil supply passage 15 stops, The amount of decrease in the hydraulic oil level is suppressed. Therefore, when the engine is restarted, only a small amount of hydraulic oil is needed to fill the pressure chamber 14 with the hydraulic oil, and the reduction in the damper action immediately after the engine is restarted can be more effectively suppressed. It is possible. Other functions and effects are the same as those of the first embodiment.

  In each of the above-described embodiments, the exterior type chain tensioners 1 and 40 of the type in which the cylinder 9 is fitted into the tensioner mounting hole 12 of the engine cover 11 have been described as an example, but the present invention is accommodated in the engine cover 11. The present invention can also be applied to an internal chain tensioner of the type in which the cylinder 9 is fixed to the side surface of the engine block.

DESCRIPTION OF SYMBOLS 1 Chain tensioner 9 Cylinder 10 Plunger 10A Tubular body 10B Cap member 13 Check valve 14 Pressure chamber 15 Oil supply passage 16 Oil introduction hole 17 Reservoir chamber 20 Valve seat 21 Valve body 22 Valve spring 24 Valve hole 25 Seat surface 26 Inner peripheral surface 28 Leak Clearance 29 Female thread 30 Male thread 31 Screw rod 32 Pressure side flank 33 Play side flank 34 Return spring 40 Chain tensioner 41 Register ring 42 Housing groove 43 Circumferential groove 44 Tapered surface 45 Stopper surface

Claims (9)

A cylindrical cylinder (9) whose one end is open and whose other end is closed, a bottomed cylindrical plunger (10) which is slidably inserted in the cylinder (9) in the axial direction, and its plunger ( 10) a return spring (34) for urging the cylinder (9) in a protruding direction, a check valve (13) incorporated in the cylinder (9), the check valve (13) and the plunger (10) A chain tensioner having a pressure chamber (14) formed between the pressure chamber (14) and an oil supply passage (15) for introducing hydraulic oil into the pressure chamber (14) via the check valve (13).
The check valve (13) includes a valve seat (20) having a valve hole (24) communicating between the oil supply passage (15) and the pressure chamber (14), and a pressure chamber (14) of the valve hole (24). A valve body (21) movably provided between a valve closing position in contact with the seat surface (25) formed at the end of the) side and a valve opening position away from the seat surface (25); A valve spring (22) for urging the valve body (21) from the valve opening position toward the valve closing position;
The oil supply passage (15) is connected to an oil introduction hole (16) for introducing hydraulic oil from the outside of the cylinder (9) and a downstream side of the oil introduction hole (16), and upstream of the check valve (13). A chain tensioner comprising a reservoir chamber (17) formed adjacent to the side.   A leak gap (in which the inner periphery of the plunger (10) is fitted to the outer periphery of the valve seat (20) so as to be slidable in the axial direction, and hydraulic fluid in the pressure chamber (14) flows out between the fitting surfaces. 28. The chain tensioner according to claim 1, wherein 28) is formed.   A cylindrical body (10A) having a cylindrical inner peripheral surface (26) that fits the outer periphery of the valve seat (20) is opened at both ends, and one end of the cylindrical body (10A). The chain tensioner according to claim 2, comprising a cap member (10B) fitted and fixed.   The chain tensioner according to claim 3, wherein the cap member (10B) is fixed by press-fitting the cap member (10B) into the cylindrical body (10A).   The chain tensioner according to any one of claims 2 to 4, wherein a radial clearance of the leak gap (28) is set smaller than a radial clearance between sliding surfaces of the plunger (10) and the cylinder (9).   The reservoir chamber (17) is formed in a cylindrical hole extending from the check valve (13) toward the closed end of the cylinder (9), and the end of the reservoir chamber (17) on the closed end side of the cylinder (9) The chain tensioner according to any one of claims 1 to 5, wherein the oil introduction hole (16) is connected to a portion.   The chain tensioner according to any one of claims 1 to 6, wherein the reservoir chamber (17) is formed to have a volume of 50% or more of an internal volume of the plunger (10).   A screw rod (31) having a male screw (30) threadedly engaged with a female screw (29) formed on the inner periphery of the plunger (10) is provided on the outer periphery, and the screw rod (31) from the plunger (10) is provided. The protruding end is brought into contact with the valve seat (20), and the male screw (30) and the female screw (29) receive pressure when a load is applied in a direction in which the plunger (10) is pushed into the cylinder (9). The chain tensioner according to any one of claims 1 to 7, wherein the flank angle of the pressure side flank (32) is formed in a sawtooth shape larger than the flank angle of the play side flank (33).   A register ring (41) for elastically fastening the outer periphery of the plunger (10) is accommodated in an annular accommodating groove (42) formed on the inner periphery of the cylinder (9), and the register ring (41) is The plunger (10) is engaged with a circumferential groove (43) formed at a constant interval in the axial direction on the outer periphery of the plunger (10), and the plunger (10) is placed in a cylinder ( 9) When a load in the direction of projecting from 9) is applied, the diameter of the register ring (41) is increased to allow the plunger (10) to move, and the plunger (10) is connected to the cylinder (9). 8) A stopper surface (45) is provided for locking the register ring (41) and restricting the movement of the plunger (10) when a load in a direction to be pushed into is applied. Any Of the chain tensioner.

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