JP2010127346A - Hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic tensioner which can reduce a tension of wrapping transmitting member throughout a traveling speed of the wrapping transmitting member by making the leak down property variable, and extend a life of the wrapping transmitting member. <P>SOLUTION: A hydraulic tensioner 24, in which a tension of timing chain 21 is adjusted based on a projecting amount of plunger 28, includes a pinion 42, which engages with a rack tooth 29 formed on a periphery of the plunger 28, and a rack tooth 41 formed on a periphery of spool 39, wherein the spool 39 is formed in a profile that a cross-sectional area becomes smaller as it advances toward a direction equivalent to a projecting direction of the plunger 28 and a clearance between a circumference of communicating hole 38 and the spool 39 is made to be variable in magnitude based on a displacement of the spool 39. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydraulic tensioner, and more particularly to a hydraulic tensioner that maintains a constant tension of a wound transmission member such as a timing chain for driving a camshaft of an internal combustion engine.

  As a hydraulic tensioner that maintains a constant tension of a winding transmission member such as a timing chain for driving a camshaft of an internal combustion engine, a housing having a cylinder hole attached to a cylinder block, and a movably provided in the cylinder hole Plunger, a return spring that urges the plunger to protrude from the cylinder hole, and hydraulic oil supplied from a hydraulic pressure source when the plunger protrudes into the cylinder hole to apply hydraulic pressure to the plunger. What is provided with the non-return valve which blocks | retreats backward movement is known.

  In this hydraulic tensioner, the timing chain is pressed by a plunger to which an outward projecting output is applied by a return spring, and the pushing force applied to the plunger from the timing chain is buffered by hydraulic oil in the cylinder hole. The timing chain is prevented from flapping and the tension of the timing chain is kept constant.

  In a valve operating system for an internal combustion engine or the like, the rotational speed of the internal combustion engine changes in an extremely wide rotational range from the idle rotational range to the high rotational range, and accordingly, the moving speed and tension of the timing chain also change greatly. For this reason, if the rotational speed of the internal combustion engine matches the resonance point (resonance frequency) of the timing chain determined from the span length and chain tension of the timing chain, it is inevitable that the chain span resonates and vibrates laterally. The chain tension greatly fluctuates due to the resonance of the chain span.

  For this reason, in the conventional hydraulic tensioner, when an excessive pressing force is applied to the plunger from the timing chain that is over tensioned due to an increase in the tension of the timing chain due to the resonance of the chain span, the hydraulic pressure in the cylinder hole is reduced. In some cases, an excessive pressing reaction force acts on the timing chain from the plunger, and as a result, the friction of the timing chain may increase.

  In this way, when the pressing force due to the tension of the timing chain is greater than the pressing force of the return spring and the hydraulic pressure in the cylinder hole, the hydraulic oil in the cylinder hole is removed from the leak gap formed between the plunger and the sliding surface of the plunger. It leaks to the outside and slowly moves backward to a position where the pushing force of the plunger, the pressing force of the return spring, and the hydraulic pressure in the cylinder hole are balanced (see, for example, Patent Document 1).

  Here, the leak down time when the hydraulic oil in the cylinder hole leaks to the outside through the leak gap is an important factor that determines the performance of the hydraulic tensioner, and this leak down time is determined by the hydraulic oil in the cylinder hole. Depending on the speed of oil leakage, the longer one is more rigid as a tensioner and can hold the timing chain at a higher tension, but if the leak down time becomes longer than necessary, the timing chain will become over-tensioned. As a result, the fatigue of the timing chain increases and the life of the timing chain is shortened, which is not preferable.

Conversely, when the leak down time is short, the tension of the timing chain can be kept low, but if it is extremely short, the displacement of the plunger becomes excessive, causing abnormal noise. For this reason, when managing the leak down time of the hydraulic tensioner, conventionally, the size and length of the leak gap formed between the sliding surfaces of the plunger and the cylinder hole are adjusted.
JP 2008-157380 A

  However, in such a conventional hydraulic tensioner, the leak-down characteristic is set by adjusting the size and length of the leak gap formed between the sliding surfaces of the plunger and the cylinder hole. Since only one leak-down characteristic can be set for one hydraulic tensioner, a resonance point due to a chain span cannot be avoided.

  That is, the resonance point due to the chain span changes depending on the leak-down characteristic, and as shown in FIG. 5A, the leak-down time is shortened (the amount of hydraulic oil leaked from the leak gap is increased). When the leak gap is adjusted, a resonance point due to the chain span is generated in the middle rotation range of the internal combustion engine, so that the leak down time becomes longer as shown by B in FIG. When the leak gap was adjusted so that the amount of hydraulic oil leaked from the engine was reduced, a resonance point due to the chain span occurred in the high rotation range of the internal combustion engine.

  Therefore, when the initial value of the leak down time is adjusted to one of the above-mentioned lengths, the resonance point due to the chain span cannot be completely avoided, so the timing chain tension increases due to the timing chain resonance. End up. As a result, the fatigue of the timing chain may increase and the life of the timing chain may be shortened.

  The present invention has been made to solve the above-described conventional problems, and reduces the tension of the winding transmission member over the entire moving speed of the winding transmission member by varying the leak-down characteristic. It is an object of the present invention to provide a hydraulic tensioner that can extend the life of a winding transmission member.

  In order to achieve the above object, a hydraulic tensioner according to the present invention includes (1) a housing having a cylinder hole, a plunger that is movably provided in the cylinder hole, and abuts against a winding transmission member that circulates, An urging means for urging the plunger so as to protrude from the cylinder hole; and hydraulic oil supplied from a hydraulic pressure source when the plunger protrudes is introduced into the cylinder hole to apply hydraulic pressure to the plunger, and A hydraulic tensioner that includes a check valve that prevents backflow of hydraulic oil introduced into the cylinder hole and adjusts the tension of the winding transmission member in accordance with the protrusion amount of the plunger. A housing hole formed in the housing so as to extend in substantially the same direction as the extending direction of the cylinder and having a communication hole communicating with the cylinder hole A shaft member provided in the housing hole so as to move in a direction substantially the same as the protruding / retreating direction of the plunger, a shaft member closing the communication hole, and rotatably supported by the housing, and an outer peripheral portion of the plunger A first rack portion formed on the outer periphery of the shaft member and a pinion meshing with a second rack portion formed on the outer peripheral portion of the shaft member, and the shaft member is cut in the same direction as the protruding direction of the plunger. The shape is such that the area is small, and the size of the gap between the peripheral edge of the communication hole and the shaft member is variable as the shaft member moves.

  With this configuration, when the tension of the winding transmission member becomes small, the plunger is biased by the hydraulic pressure and the biasing means and moves in a direction protruding from the cylinder hole to absorb the slack of the winding transmission member. When the tension of the hanging transmission member increases, the plunger is pushed into the cylinder hole against the biasing force of the biasing means and the hydraulic pressure in the cylinder hole, thereby absorbing the tension of the winding transmission member.

  At this time, since the check valve is closed, the hydraulic oil in the cylinder hole is leaked to the outside from the groove, so that the pressing force from the winding transmission member to the plunger due to the tension, the urging force of the urging means, and the hydraulic pressure in the cylinder hole It is possible to stabilize the tension of the winding transmission member by slowly moving the plunger back to the position where it is balanced.

  Further, the higher the moving speed of the winding transmission member (for example, the higher the rotational speed of the internal combustion engine), the higher the tension of the winding transmission member and the higher the hydraulic pressure supplied to the cylinder hole. The tension of the winding transmission member is adjusted by increasing the protruding amount of the plunger.

  In the present invention, a pinion that meshes with the first rack portion formed on the outer peripheral portion of the plunger and the second rack portion formed on the outer peripheral portion of the shaft member is provided, and the shaft member is disposed in the same direction as the plunger protruding direction. Since the cross-sectional area becomes smaller as it goes in the direction, and the size of the gap between the peripheral edge of the communication hole and the shaft member is changed with the movement of the shaft member, when the plunger protrudes, As the plunger moves, the shaft member moves in a direction opposite to the protruding direction of the plunger via the first rack portion, the pinion and the second rack portion.

  At this time, since the outer peripheral surface of the shaft member having a small cross-sectional area closes the communication hole, the clearance between the peripheral edge of the communication hole and the shaft member is increased, and the amount of hydraulic oil leaked from the cylinder hole through the communication hole is increased. Hydraulic oil leak down time is shortened. For this reason, the hydraulic pressure in the cylinder hole can be quickly reduced during high-speed movement of the winding transmission member having a large tension, and a large damping effect can be exerted to suppress resonance due to the span of the winding transmission member.

  In addition, when the moving speed of the winding transmission member is low (for example, the rotational speed of the internal combustion engine is low), the tension of the winding transmission member is smaller than that during high-speed movement, and the hydraulic pressure supplied to the cylinder hole is also low. Since it becomes low, the tension | tensile_strength of a winding transmission member is adjusted because the protrusion amount of a plunger decreases.

  At this time, when the plunger is pushed into the cylinder hole, the shaft member moves in the opposite direction (protruding direction) to the protruding direction of the plunger via the first rack portion, the pinion and the second rack portion as the plunger moves. Move to.

  At this time, since the outer peripheral surface of the shaft member having a large cross-sectional area closes the communication hole, the gap between the periphery of the communication hole and the shaft member is reduced, and the amount of hydraulic oil leaked from the cylinder hole through the communication hole is reduced. , Hydraulic oil leak down time is prolonged. For this reason, it is possible to keep the hydraulic pressure in the cylinder hole high during low-speed movement of the winding transmission member with low tension, and to suppress resonance due to the span of the winding transmission member.

  In this way, the gap between the peripheral edge of the communication hole and the shaft member can be varied by moving the shaft member having a different cross-sectional area as the amount of protrusion of the plunger changes according to the moving speed of the winding transmission member. As a result, the amount of hydraulic oil leaked from the cylinder hole can be varied, and the leak-down characteristic of the hydraulic oil can be changed, and the resonance due to the span of the winding transmission member is suppressed over the entire moving speed of the winding transmission member. be able to. As a result, the tension of the winding transmission member can be reduced over the entire moving speed of the winding transmission member, and the life of the winding transmission member can be extended.

  According to the present invention, by changing the leak-down characteristic, the tension of the winding transmission member can be reduced over the entire moving speed of the winding transmission member, and the life of the winding transmission member can be extended. An expression tensioner can be provided.

Hereinafter, embodiments of a hydraulic tensioner according to the present invention will be described with reference to the drawings.
1 to 4 are diagrams showing an embodiment of a hydraulic tensioner according to the present invention, and show an example in which the hydraulic tensioner of the present embodiment is applied to an internal combustion engine of a vehicle.
First, the configuration will be described.
In FIG. 1, an engine 11 that is an internal combustion engine includes a cylinder block 12 having a plurality of cylinders arranged in a longitudinal direction of the vehicle (a direction orthogonal to the paper surface in FIG. 1), and a cylinder mounted on the cylinder block 12. And a head 13.

  A crankshaft 14 that is an output shaft of the engine 11 and is disposed so as to extend in the front-rear direction of the vehicle is rotatably supported by the cylinder block 12. The cylinder head 13 supports a combustion chamber for each cylinder. An intake valve for opening and closing a connection portion (intake port) of the intake passage and an exhaust valve (both not shown) for opening and closing a connection portion (exhaust port) of the exhaust passage to the combustion chamber for each cylinder are provided.

  In addition, an intake camshaft 15 for opening and closing the intake valve and an exhaust camshaft 16 for opening and closing the exhaust valve are disposed in the cylinder head 13 substantially parallel to the crankshaft 14. These intake camshaft 15 and exhaust camshaft 16 are rotatably supported on the cylinder head 13 by bearings.

  In order to transmit the rotation of the crankshaft 14 to the intake camshaft 15 and the exhaust camshaft 16, a crank sprocket 17 is attached to the front end of the crankshaft 14 so as to be integrally rotatable.

  Cam sprockets 18 and 19 are respectively attached to the front end portions of the intake camshaft 15 and the exhaust camshaft 16 so as to be integrally rotatable. The crank sprocket 17 and the cam sprockets 18 and 19 are wound as transmission members. The timing chain 21 is wound.

  For this reason, the intake camshaft 15 and the exhaust camshaft 16 are driven to rotate by the rotation of the crankshaft 14 being transmitted via the timing chain 21 that moves around.

  Further, the engine 11 is operated by hydraulic oil to change the rotational phase of the camshaft (here, the intake camshaft 15) with respect to the crankshaft 14, thereby opening and closing the intake valve driven by the intake camshaft 15. A variable valve timing mechanism (VVT) 22 for changing the timing is provided. Further, a hydraulic pump (not shown) is connected to the crankshaft 14, and the hydraulic pump supplies hydraulic oil to a hydraulic tensioner 24 described later as the crankshaft 14 rotates.

  Near the outer side of the chain span 21a located between the crank sprocket 17 and the cam sprocket 18, a chain damper 23 is provided for regulating and attenuating the swing of the chain span 21a.

  The engine 11 is provided with a hydraulic tensioner 24 for adjusting the tension applied to the timing chain 21 to be constant. The hydraulic tensioner 24 is a chain between the crank sprocket 17 and the cam sprocket 19. A tension lever 25 is provided near the outside of the span 21b.

  The tension lever 25 is supported at the lower end thereof by a shaft 25a so as to be swingable with respect to the cylinder head 13 in the vehicle width direction (left-right direction in FIG. 1).

  As shown in FIG. 2, the hydraulic tensioner 24 includes a bottomed housing 27 having a cylinder hole 26, and a plunger 28 is slidably accommodated in the cylinder hole 26. The plunger 28 is formed in a bottomed cylindrical shape with one end opened, and rack teeth 29 as a first rack portion are formed on the outer peripheral surface of the plunger 28 in the longitudinal direction.

  A return spring 30 as an urging means is disposed inside the plunger 28 between the bottom of the cylinder hole 26, and the return spring 30 projects in the direction in which the plunger 28 protrudes from the cylinder hole 26 (rightward in FIG. 2). ).

  The plunger 28 presses the chain span 21 b via the tension lever 25 by the return spring 30 to apply tension to the timing chain 21. This tension is adjusted according to the protruding amount of the plunger 28. Is done.

  The housing 27 is provided with an oil supply hole 31, which is connected to a hydraulic pump through an oil supply passage (not shown). The oil supply hole 31 is supplied with oil from a hydraulic pump as a hydraulic source. The hydraulic oil is supplied through the passage.

  The housing 27 located at the bottom of the cylinder hole 26 is provided with a check valve 32. The check valve 32 has a ball seat portion 33b in which an oil supply hole 33a is formed and an oil supply hole 33c. The spring receiving portion 33d with which the return spring 30 abuts, the check ball 34 provided between the ball seat portion 33b and the spring receiving portion 33d, one end abutting against the spring receiving portion 33d and the other end with the check ball And a coil spring 35 that urges the check ball 34 in a direction to close the oil supply hole 33a.

  In the check valve 32, when the hydraulic oil supplied from the hydraulic pump acts on the check ball 34 via the oil supply hole 31 and the oil supply hole 33 a, the check ball 34 resists the urging force of the coil spring 35. The hydraulic fluid is allowed to flow into the cylinder hole 26 by moving toward the spring receiving portion 33d.

  When the hydraulic oil in the cylinder hole 26 acts on the check ball 34, the check ball 34 is urged by the coil spring 35 and moves toward the ball seat portion 33b, thereby closing the oil supply hole 33a. Is prevented from flowing out of the cylinder hole 26.

  On the other hand, a housing hole 36 is formed in the housing 27, and the housing hole 36 extends in substantially the same direction as the extending direction of the cylinder hole 26. A communication hole 38 is formed in the housing hole 36, and the communication hole 38 communicates the cylinder hole 26 and the housing hole 36.

  A spool 39 as a shaft member is accommodated in the housing hole 36, and the spool 39 moves in substantially the same direction as the protrusion / retraction direction of the plunger 28 and closes the communication hole 38. Further, rack teeth 41 as second rack portions are formed on the outer peripheral surface of the spool 39.

  A discharge hole 40 is formed in the housing hole 36, and hydraulic oil in the cylinder hole 26 is discharged from the discharge hole 40 to the outside of the housing 27 through the communication hole 38 and the housing hole 36. Yes.

  A pinion 42 is rotatably supported on the housing 27, and the pinion 42 meshes with the rack teeth 29 of the plunger 28 and the rack teeth 41 of the spool 39. Therefore, when the plunger 28 protrudes from the housing 27, the spool 39 moves in a direction to be pushed (retracted) into the housing hole 36 through the pinion 42 as the plunger 28 moves, and the plunger 28 is pushed into the housing 27. As the plunger 28 moves, the spool 39 moves in a direction protruding from the housing hole 36 via the pinion 42. That is, the spool 39 moves in the direction opposite to the moving direction of the plunger 28.

  On the other hand, the spool 39 is formed in such a shape that its cross-sectional area becomes smaller as it goes in the same direction as the protruding direction of the plunger 28, and the clearance between the peripheral edge of the communication hole 38 and the spool 39 as the spool 39 moves. The size of can be changed.

  That is, the spool 39 continues to the cylindrical large diameter portion 39a, the cylindrical large diameter portion 39a, the conical portion 39b that gradually decreases in cross-sectional area toward the protruding direction of the plunger 28, and the conical portion 39b. It is comprised from the rack tooth | gear part 39c in which the tooth | gear 41 was formed. In the present embodiment, the cylindrical large-diameter portion 39a and the conical portion 39b close the communication hole 38 as the spool 39 moves forward and backward.

Next, the operation will be described.
When hydraulic oil is supplied from the hydraulic pump to the oil supply hole 33 a through the oil supply hole 31, the check ball 34 moves toward the spring receiving portion 33 d against the biasing force of the coil spring 35, and the hydraulic oil is supplied to the cylinder hole 26. Is done. For this reason, the plunger 28 protrudes from the cylinder hole 26 and the tension lever 25 is pressed.

  At this time, the tension lever 25 swings about the shaft 25a and the timing chain 21 is pressed, whereby a predetermined tension is applied to the timing chain 21. For this reason, the occurrence of slack in the timing chain 21 is prevented, and fluttering of the timing chain 21 is prevented.

Here, the tension of the timing chain 21 increases as the rotational speed of the engine 11 increases. This is because the meshing speed between the teeth of the crank sprocket 17 and the cam sprockets 18 and 19 and the timing chain 21 increases as the rotational speed of the engine 11 increases.
Further, the hydraulic pump increases the hydraulic oil supplied to the hydraulic tensioner 24 as the rotation speed of the crankshaft 14 becomes higher.

  Therefore, the plunger 28 protrudes from the cylinder hole 26 as the tension of the timing chain 21 increases, that is, the higher the rotational speed of the engine 11 (the higher the moving speed of the timing chain 21), the longer the tension lever. By pressing 25, it is possible to prevent the slack of the timing chain 21 from occurring.

  Here, when the engine 11 is rotating at a low speed and at a high speed, that is, when the timing chain 21 is moving at a low speed and at a high speed, the protruding amount of the plunger 28 is different. As shown in FIG. The protrusion amount of the plunger 28 at the time of low rotation is in a state of being pushed into the cylinder hole 26 as compared to at the time of high rotation.

  When the pressing force due to the tension of the timing chain 21 is larger than the pressing force of the return spring 30 and the hydraulic pressure in the cylinder hole 26 due to the tension fluctuation due to the resonance of the chain span 21b of the timing chain 21 when the engine 11 rotates at a low speed, Since the check ball 34 closes the oil supply hole 33a and increases the hydraulic pressure in the cylinder hole 26, the hydraulic oil in the cylinder hole 26 is leaked to the outside from the communication hole 38 through the housing hole 36 and the discharge hole 40. The plunger 28 is slowly pushed into the cylinder hole 26 to a position where the pushing force of the plunger 28 and the pushing force of the return spring 30 and the hydraulic pressure in the cylinder hole 26 are balanced, and flapping of the timing chain 21 is prevented.

  In the present embodiment, when the amount of protrusion of the plunger 28 is small, that is, when the amount of retraction of the plunger 28 is large with respect to the cylinder hole 26, the spool 39 is moved through the pinion 42 with the retracting movement of the plunger 28. It moves in a direction protruding from 36. For this reason, as shown in FIG. 2, since the communication hole 38 is closed by the cylindrical large diameter portion 39a having the largest cross-sectional area in the spool 39, the clearance between the peripheral edge of the communication hole 38 and the cylindrical large diameter portion 39a And the amount of hydraulic fluid leaked from the cylinder hole 26 through the communication hole 38 is reduced.

  For this reason, the hydraulic oil leakage down time becomes longer, and the hydraulic pressure in the cylinder hole 26 can be kept high when the timing chain 21 with low tension is moved at low speed, thereby suppressing the resonance of the timing chain 21 due to the chain span 21b.

  On the other hand, when the pressing force due to the tension of the timing chain 21 is greater than the pressing force of the return spring 30 and the hydraulic pressure in the cylinder hole 26 due to the tension fluctuation due to the resonance of the chain span 21b of the timing chain 21 when the engine 11 rotates at a high speed, The check ball 34 closes the oil supply hole 33a and increases the hydraulic pressure in the cylinder hole 26.

  At this time, the hydraulic oil in the cylinder hole 26 is leaked to the outside from the communication hole 38, so that the plunger 28 is slowly moved to a position where the pushing force of the plunger 28, the pressing force of the return spring 30 and the hydraulic pressure of the cylinder hole 26 are balanced. And the timing chain 21 is prevented from flapping.

  The protrusion amount of the plunger 28 when the engine 11 rotates at a high speed is larger than the protrusion amount of the plunger 28 when the engine 11 rotates at a low speed. Therefore, as shown in FIG. 3, when the protrusion amount of the plunger 28 increases with respect to the cylinder hole 26, the spool 39 is pushed into the housing hole 36 via the pinion 42 as the plunger 28 moves. Moving.

  For this reason, as shown in FIG. 3, since the communication hole 38 is closed by the conical portion 39b having a smaller cross-sectional area than the large cylindrical portion 39a, there is a gap between the peripheral edge of the communication hole 38 and the large cylindrical portion 39a. growing. For this reason, the amount of hydraulic oil leaked from the cylinder hole 26 through the communication hole 38 increases, and the leak down time is shortened.

  As a result, it is possible to quickly reduce the hydraulic pressure in the cylinder hole 26 at the time of high rotation of the engine 11 where the tension of the timing chain 21 is large, exhibit a damping effect, and suppress resonance due to the chain span 21b.

  As described above, in the present embodiment, the rack teeth 29 formed on the outer peripheral portion of the plunger 28 and the pinion 42 that meshes with the rack teeth 41 formed on the outer peripheral portion of the spool 39 are provided. Since the cross-sectional area is reduced as it goes in the same direction as the direction, the size of the gap between the peripheral edge of the communication hole 38 and the spool 39 can be changed as the spool 39 moves. The amount of hydraulic oil leaked from the hole 26 can be varied to change the leak-down characteristic of the hydraulic oil, and resonance due to the chain span 21b of the timing chain 21 can be suppressed over the entire moving speed of the timing chain 21.

  As a result, as shown in FIG. 4, the tension of the timing chain 21 can be reduced over the entire rotation region of the engine 11, and the life of the timing chain 21 can be extended.

  Further, the broken line indicates the tension of the timing chain 21 with respect to the engine speed from 1000 rpm to 6000 rpm when a conventional hydraulic tensioner set to be constant so as to shorten the leak down time is used. In this case, resonance occurs due to the chain span 21b of the timing chain 21 in the medium speed rotation region of the engine.

  The alternate long and short dash line indicates the tension of the timing chain 21 with respect to the engine speed from 1000 rpm to 6000 rpm when a conventional hydraulic tensioner set to be constant so as to increase the leak down time. In this case, resonance occurs due to the chain span 21b of the timing chain 21 in the high speed rotation region of the engine.

  The solid line indicates the tension of the timing chain 21 with respect to the engine speed from 1000 rpm to 6000 rpm when the hydraulic tensioner 24 of the present embodiment is used. In the present embodiment, the solid line represents the rotation region of the engine 11. It can be seen that the tension of the timing chain 21 can be reduced over the entire area.

  In this embodiment, the timing chain 21 is used as the winding transmission member, but a belt or the like may be used as the winding transmission member.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

  As described above, the hydraulic tensioner according to the present invention can reduce the tension of the winding transmission member over the entire range of the moving speed of the winding transmission member by varying the leak-down characteristic. This is useful as a hydraulic tensioner or the like that keeps the tension of a winding transmission member such as a timing chain for driving a camshaft of an internal combustion engine constant.

1 is a diagram showing an embodiment of a hydraulic tensioner according to the present invention, and is a configuration diagram of a main part of an internal combustion engine provided with the hydraulic tensioner. It is a figure showing one embodiment of the hydraulic tensioner concerning the present invention, and is a sectional view of a hydraulic tensioner. It is a figure which shows one Embodiment of the hydraulic tensioner which concerns on this invention, and is a figure which shows the protrusion amount of the plunger at the time of the low rotation of an engine and the high rotation. It is a figure which shows one Embodiment of the hydraulic tensioner which concerns on this invention, and is a figure which shows the relationship between the engine speed and tension | tensile_strength of a timing chain in the past and this Embodiment. It is a figure which shows the relationship between the conventional engine speed and the tension | tensile_strength of a timing chain, and is a figure which shows the relationship between the engine speed and the tension | tensile_strength of a timing chain when leak down time is shortened and lengthened.

Explanation of symbols

21 Timing chain (winding transmission member)
24 Hydraulic Tensioner 26 Cylinder Hole 27 Housing 28 Plunger 29 Rack Teeth (First Rack Part)
30 Return spring (biasing means)
32 Check valve 36 Housing hole 38 Communication hole 39 Spool (shaft member)
41 Rack teeth (second rack part)
42 Pinion

Claims (1)

A housing having a cylinder hole, a plunger that is movably provided in the cylinder hole and that abuts on a winding transmission member that circulates, and a biasing means that biases the plunger so as to protrude from the cylinder hole; A check valve that introduces hydraulic oil supplied from a hydraulic pressure source into the cylinder hole when the plunger protrudes to apply hydraulic pressure to the plunger, and prevents backflow of the hydraulic oil introduced into the cylinder hole; Prepared,
In the hydraulic tensioner that adjusts the tension of the winding transmission member according to the protrusion amount of the plunger,
A housing hole formed in the housing so as to extend in substantially the same direction as the extending direction of the cylinder hole, and having a communication hole communicating with the cylinder hole, and substantially in the same direction as the protruding / retracting direction of the plunger A shaft member which is provided in the housing hole so as to move and which closes the communication hole, a first rack portion which is rotatably supported by the housing and is formed on an outer peripheral portion of the plunger, and the shaft A pinion that meshes with a second rack portion formed on the outer periphery of the member,
The shaft member is formed in a shape such that a cross-sectional area becomes smaller as it goes in the same direction as the protruding direction of the plunger, and a gap between the peripheral edge of the communication hole and the shaft member as the shaft member moves. A hydraulic tensioner characterized in that its size is variable.

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