JP2009293636A - Ratchet-type hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent flapping of a plunger at start of an engine in a ratchet-type hydraulic tensioner. <P>SOLUTION: An operating body 20 operated by hydraulic pressure is inserted to an oil chamber 18 within a first plunger 12. When hydraulic pressure is not applied to the oil chamber 18, a second plunger 28 has a first attitude A pressed against the first plunger 12 by energizing force of a spring 29 on the operating body 20 side. When hydraulic pressure is applied to the oil chamber 18, the second plunger 28 is pressed into an operation cylinder 27 resisting to the energizing force of the spring 29 by the force of the hydraulic pressure so as to have a second attitude B changed from the first attitude A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ratchet type hydraulic tensioner used for applying appropriate tension to a timing chain of a vehicle engine.

  As is well known, vibrations that occur during travel of the timing chain that transmits rotation between the crankshaft side sprocket of the engine and the camshaft side sprocket paired on the intake side and exhaust side are suppressed, and an appropriate tension is applied. In order to maintain, tensioners are widely adopted.

  In this tensioner, the plunger protruding from the housing is pivotally supported on the engine body side so as to swing freely and presses the back surface near the swing end of the chain slipper, so that the shoe surface of the chain slipper slides toward the slack side of the chain. It is set as the structure which contacts and adds tension | tensile_strength.

  Recently, various ratchet hydraulic tensioners having a ratchet locking mechanism and a check ball mechanism have been proposed.

  Typical examples of this type of ratchet hydraulic tensioner include those proposed in Patent Documents 1 and 2.

  The ratchet type hydraulic tensioner proposed in Patent Document 1 is an oversupply that discharges excess supply oil to the outside of the housing in an oil supply path extending from an oil supply port side to the check ball mechanism by supplying oil from a hydraulic source. By connecting the oil discharge passage, excessive supply into the plunger is suppressed, and noise called “hue” is reduced.

  On the other hand, in the ratchet type hydraulic tensioner proposed in Patent Document 2, two oil sump portions for stagnating oil pumped from a hydraulic power source and supplying it to the check ball mechanism are recessed in the housing. It is configured to prevent the plunger from popping out abnormally when oil is excessively supplied from a hydraulic source by drilling an oil amount adjusting throttle hole communicating with each other in a partition wall that partitions the oil reservoir. Yes.

  The structure of the ratchet hydraulic tensioner, which is the basis of the techniques described in Patent Documents 1 and 2, will be described with reference to FIG.

  Referring to FIG. 6, a basic ratchet hydraulic tensioner 100 is provided with a plunger 101 slidably with respect to a housing 102 and urges the plunger 101 in a protruding direction by a return spring 103. A check ball mechanism 105 is provided between the oil chamber 104 provided in the plunger 101 and the housing 102.

  When loosening occurs in the timing chain wound between the sprockets, a gap is formed between the check ball 106 and the ball seat 107 constituting the check ball mechanism 105, so that the oil flow is allowed and generated by a hydraulic pump (not shown). The oil pressure acts in the oil chamber 104 via the oil passage, and the plunger 101 moves forward by the oil pressure and the urging force of the return spring 103 to press the chain slipper.

  When the plunger 101 tries to move in the opposite direction, the check ball 106 comes into close contact with the ball seat 107, so that the oil in the oil chamber 104 does not move.

The ratchet type hydraulic tensioner 100 has a rack 108 formed on the peripheral surface of the plunger 101, and is pivotally supported by the housing 102 with respect to the rack 108, and is attached to the spring 109 in a direction opposite to the protruding direction of the plunger 101. The urged ratchet 110 is engaged. Therefore, when the hydraulic pressure in the oil chamber 104 does not reach an appropriate value immediately after starting the engine or during idling, the ratchet 110 that meshes with the rack 108 of the plunger 101 prevents the plunger 101 from returning stepwise. ing. As a result, the plunger 101 can be prevented from retreating and the tension of the timing chain can be maintained.
JP 2003-206999 A JP 2003-278859 A

  Incidentally, in the conventional ratchet hydraulic tensioner 100 shown in FIG. 6, the following problems have been pointed out.

  The oil accumulated in the oil chamber 104 inside the tensioner 100 leaks through a gap generated between the housing 102 and the plunger 101 while the engine is stopped. for that reason. The oil chamber 104 when the engine is started after being left for a long time is in a two-layer state of an oil layer 111 and an air layer 112. When the engine is started in this state, the plunger 101 flutters due to the air layer 112, and a hitting sound may occur between the plunger 101 and the chain slipper.

  FIG. 7 shows an example of a vibration waveform in which abnormal noise is generated due to fluttering by the air layer 112 of the tensioner 100. From this figure, it can be seen that fluttering occurs until the hydraulic pressure supplied to the tensioner 100 rises and when air enters the tensioner 100 in the oil passage of the engine.

  As described above, the return spring 103 is inserted into the ratchet type hydraulic tensioner 100. However, the rotational fluctuation, that is, the torque fluctuation cannot be suppressed only by the urging force of the return spring 103.

  Although it is conceivable to prevent the plunger 101 from fluttering by increasing the urging force of the return spring 103, the tension of the timing chain becomes high during normal operation, and the durability of the timing chain cannot be ensured. Therefore, this method cannot be adopted.

  The present invention has been made in view of the above technical problem, and an object of the present invention is to provide a ratchet type hydraulic tensioner that can prevent the plunger from flapping when the engine is started after being left for a long time.

  To achieve the above object, the ratchet hydraulic tensioner according to the present invention is suitable for a timing chain that transmits rotation between a crankshaft side sprocket of an engine and a camshaft side sprocket that is paired on an intake side and an exhaust side. A ratchet type hydraulic tensioner used for applying tension, a first plunger that is fitted in a housing hole formed in the housing so as to be reciprocally movable in the front-rear direction, and a timing at which the first plunger travels A first urging means for urging the first plunger in the forward direction so as to protrude from the housing toward the chain, and oil pressure-fed from the oil supply port to an oil chamber provided inside the first plunger Check ball mechanism that prevents the reverse flow by flowing in, and inserted into the oil chamber in front of the check ball mechanism An actuating body actuated by hydraulic pressure, the actuating body having a rear end fixed to the bottom of the receiving hole and a front end facing the oil chamber; When the hydraulic pressure is not applied to the oil chamber and the second plunger fitted in a freely reciprocating manner, the second plunger is set to the first posture to press the first plunger, and the hydraulic pressure is applied to the oil chamber. And a switching means for bringing the second plunger into the second posture pushed into the working cylinder.

  In the ratchet type hydraulic tensioner, the switching means is disposed in a space formed between the operating cylinder and the second plunger, and the second plunger is configured to press the first plunger. A second urging means for urging in the advancing direction; and a flange that divides the accommodation hole and the check ball mechanism at a peripheral edge of a rear end portion of the operating cylinder, and communicates the accommodation hole and the check ball mechanism. A slit for causing the second plunger to be in the first posture by the biasing force of the second biasing means when no hydraulic pressure is applied to the oil chamber, and when the hydraulic pressure is applied to the oil chamber, the hydraulic pressure is applied to the oil chamber. The second plunger is set to the second posture against the urging force of the second urging means by the force of.

  An operating body that is operated by hydraulic pressure is inserted into the oil chamber in the first plunger. Therefore, when the hydraulic pressure is not applied to the oil chamber, the second plunger is in the first posture pressed against the first plunger by the urging force of the second urging means. As a result, the first plunger pushes the timing chain by the urging forces of both the first urging means on the first plunger side and the second urging means on the operating body side. As a result, timing chain flickering at the time of starting the engine after being left for a long time can be suppressed. When the oil pressure is applied to the oil chamber, the second plunger is pushed from the first posture into the working cylinder against the urging force of the second urging means by the force of the oil pressure. Switch to posture. As a result, the first plunger pushes the timing chain by the hydraulic pressure and the urging force of the first urging means on the first plunger side.

  According to the present invention, it is possible to prevent the plunger from fluttering when the engine is started after being left for a long time.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First embodiment]
FIG. 1 is a view showing an attached state of the ratchet hydraulic tensioner T according to the first embodiment of the present invention.

  In FIG. 1, the timing chain 4 is in the direction of the arrow between the driving sprocket 1 attached to the crankshaft in the engine room and the driven sprockets 2 and 3 paired on the intake side and exhaust side attached to the camshaft. It is wrapped so that it can run.

  The tight side of the timing chain 4 is guided by a chain guide 5, and the slack side of the timing chain 4 is guided by a chain slipper 6.

  The chain slipper 6 is pressed by the ratchet type hydraulic tensioner T according to the present embodiment so as to appropriately maintain the tension of the timing chain 4.

  FIG. 2 is a cross-sectional view of the ratchet hydraulic tensioner T.

  Referring to FIG. 2, the ratchet hydraulic tensioner T according to the present embodiment includes a first plunger 12 that is fitted in a housing hole 11 formed in the housing 10 so as to be reciprocally movable in the front-rear direction, and a first plunger 12. A return spring 13 that urges the first plunger 12 in the forward direction (right side in FIG. 2) so as to protrude from the housing 10 toward the timing chain 4 on which one plunger 12 travels, and the housing 10 is swingable. A ratchet locking mechanism 16 in which the supported ratchet 14 meshes with a rack 15 carved in the first plunger 12, and an oil chamber 18 provided in the first plunger 12 with oil pumped from the oil supply port 17. A check ball mechanism 19 that flows into the flow chamber to prevent the reverse flow, and is inserted into the oil chamber 18 in front of the check ball mechanism 19, And a working member 20 operated by pressure.

  The first plunger 12 has a bottomed cylindrical shape with an open rear end so that the inside functions as the oil chamber 18. A rack 15 is provided on one side surface of the outer periphery of the first plunger 12 along the longitudinal direction thereof. A return spring 13 is interposed between the inner wall of the oil chamber 18 inside the first plunger 12 and the rear end portion of the operating body 20 so as to surround the outer periphery of the operating body 20. The first plunger 12 presses the chain slipper 6 provided on the front end face side of the first plunger 12 by the urging force of the return spring 13, and is applied to the timing chain 4 wound between the sprockets 1, 2, and 3. Giving tension to it.

  The ratchet 14 is pivotally supported by a shaft 21 provided in the housing 10 and is urged in a direction opposite to the first plunger 12 by a cam spring 22. Thereby, the ratchet locking mechanism 16 prevents the backward displacement of the first plunger 12 by engaging the claw formed on the ratchet 14 with the rack 15 on the outer periphery of the first plunger 12.

  The check ball mechanism 19 is press-fitted into an end portion of an oil passage (not shown) extending from the oil supply port 17 and can be brought into contact with the ball seat 23 and functions as a check valve. The check ball 24, the retainer 25 that holds the check ball 24, and a spring 26 that urges the check ball 24 toward the ball seat 23, allow oil to flow into the oil chamber 18 and reversely The backflow of oil from the oil chamber 18 is prevented.

  FIG. 3 shows the configuration of the operating body 20, wherein FIG. 3 (a) is a sectional view and FIG. 3 (b) is a front view.

  Referring to FIG. 3, the operating body 20 moves the second plunger 28 forward (right side in FIG. 3A) so as to press the operating cylinder 27, the second plunger 28, and the first plunger 12. And a spring 29 for biasing.

  The actuating cylinder 27 has a bottomed cylindrical shape in which the rear end is closed and the front end is open. The rear end is fixed to the bottom of the accommodation hole 11 and the front end faces the oil chamber 18. . A flange 30 that partitions the accommodation hole 11 and the check ball mechanism 19 is formed on the periphery of the rear end portion of the working cylinder 27. In the flange 30, four slits 31 for communicating the receiving hole 11 and the check ball mechanism 19 are opened at an interval of 90 degrees. The number and shape of the slits 31 are not limited to those shown in the figure, and can be arbitrarily set.

  The second plunger 28 is fitted in the operation cylinder 27 so as to be reciprocally movable in the front-rear direction. Specifically, a flange is formed on the periphery of the rear end portion of the second plunger 28, and is inserted into the working cylinder 27 in an airtight manner with the O-ring 33 fitted on the outer periphery of the flange. ing.

  The spring 29 is interposed between the bottom of the operating cylinder 27 and the flange of the second plunger 28. In particular, as described above, since the second plunger 28 is fitted in the operation cylinder 27 in an airtight manner, the interposed space of the spring 29 is an air chamber. Therefore, the spring 29 is placed in a space formed between the operating cylinder 27 and the second plunger 28 by being fitted in a tube 32 made of a stretchable material such as synthetic resin. . The tube 32 has a sealed shape, and maintains an air layer generated in a space formed between the operation cylinder 27 and the second plunger 28.

  In the above configuration, the operating body 20 that is operated by hydraulic pressure is inserted into the oil chamber 18 inside the first plunger 12. Therefore, when the hydraulic pressure is not applied to the oil chamber 18 as in the engine start after being left for a long time, the second plunger 28 is pressed against the first plunger 12 by the biasing force of the spring 29 on the operating body 20 side. The first posture A (the posture indicated by the solid line in FIG. 2) is used. Thereby, the first plunger 12 pushes the timing chain 4 by the urging force of both the return spring 13 and the spring 29 on the operating body 20 side. As a result, the flickering of the timing chain 4 when starting the engine after being left for a long time can be suppressed.

  When the timing chain 4 wound between the sprockets 1 to 3 is loosened after the engine is started, a gap is formed between the check ball 24 and the ball seat 23 to allow the oil to flow. When hydraulic pressure generated by a hydraulic pump (not shown) is applied from the oil supply port 17 to the oil chamber 18 through the slit 31 (see FIG. 3B), and the hydraulic pressure is applied to the oil chamber 18, the second plunger 28 is The first posture A is pushed into the actuating cylinder 27 against the biasing force of the spring 29 by the hydraulic force, and is switched to the second posture B (the posture indicated by the two-dot chain line in FIG. 2). As a result, the first plunger 12 pushes the timing chain 4 by the hydraulic pressure and the urging force of the return spring 13.

  Moreover, since the spring 29 is fitted in the tube 32 having elasticity, the tube 32 contracts integrally with the spring 29. Therefore, there is always air in the space formed between the operating cylinder 27 and the second plunger 28. As a result, the airtightness between the operating cylinder 27 and the second plunger 28 is not required to be severe, and even if oil flows into the space formed between the operating cylinder 27 and the second plunger 28. The oil can be returned into the oil chamber 18 by the air pressure in the space.

  As is clear from the above description, by inserting the operating body 20 that is actuated by hydraulic pressure into the oil chamber 18 of the tensioner T, it is possible to prevent the generation of noise due to flapping of the timing chain 4 when the engine is started after being left for a long time. The return spring 13 can be such that the tension of the tensioner T does not rise more than necessary during normal operation. Therefore, it is possible to ensure the durability of the timing chain 4.

[Second Embodiment]
FIG. 4 is a sectional view of a ratchet hydraulic tensioner T according to the second embodiment of the present invention. 5 shows the configuration of the operating body 20, wherein FIG. 5A is a cross-sectional view and FIG. 5B is a front view.

  With reference to these drawings, the ratchet hydraulic tensioner T according to the present embodiment is characterized in that the hydraulic pressure is applied to the oil chamber 18 and the posture of the second plunger 28 is changed from the first posture A to the second posture B. When switching to, the air in the space formed between the working cylinder 27 and the second plunger 28 is made to flow out of the tensioner T according to the pushing amount of the second plunger 28.

  Specifically, an air passage 51 having one end opened to the outside and the other end opened to the accommodation hole 11 is provided on the housing 10 side, and one end is opened to the bottom wall and pulled from the bottom to the flange 30 on the working cylinder 27 side. An air passage 52 that is rotated and has the other end opened to the accommodation hole 11 is provided, and the other end opening of the air passage 51 on the housing 10 side and the other end opening of the air passage 52 on the working cylinder 27 side are connected to each other. Has been.

  In the above configuration, when the oil pressure is applied to the oil chamber 18, the second plunger 28 operates from the first posture A that presses the first plunger 12 against the urging force of the spring 29 by the force of the oil pressure. By being pushed into the cylinder 27 and switched to the second posture B, the first plunger 12 pushes the timing chain 4 by the hydraulic pressure and the urging force of the return spring 13. At this time, in the space formed between the working cylinder 27 and the second plunger 28, an amount of air corresponding to the amount by which the second plunger 28 is pushed out of the tensioner T via the air passages 51 and 52. Since it flows out, even if a position change arises in the 2nd plunger 28, it can track.

  Other configurations, operations and effects are the same as those in the first embodiment.

  The present invention is not limited to the above embodiment.

  For example, in the first embodiment, an example has been described in which the second plunger 28 is airtightly fitted into the operation cylinder 27 via the O-ring 33. However, as described above, in the first embodiment, the spring 29 is a space formed between the operating cylinder 27 and the second plunger 28 in a state in which the spring 29 is fitted in the tube 32 having elasticity. Since the air is always present in the space, the airtightness between the working cylinder 27 and the second plunger 28 does not need to be severely required. Therefore, the second plunger 28 may be directly and airtightly fitted into the operating cylinder 27 without using the O-ring 33.

  It goes without saying that various design changes and modifications can be made within the scope of the claims attached to this specification.

It is a figure which shows the attachment state of the ratchet type hydraulic tensioner concerning the 1st Embodiment of this invention. 2 is a cross-sectional view of a ratchet hydraulic tensioner T. FIG. The structure of the action body is shown, (a) is a sectional view and (b) is a front view. It is sectional drawing of the ratchet type hydraulic tensioner concerning the 2nd Embodiment of this invention. The structure of the action body is shown, (a) is a sectional view and (b) is a front view. It is sectional drawing of the conventional ratchet type hydraulic tensioner. It is a figure which shows the example of the vibration waveform which an abnormal noise generate | occur | produces by the fluttering by the air layer of a ratchet type hydraulic tensioner.

Explanation of symbols

1-3 Sprocket 4 Timing chain T Ratchet hydraulic tensioner 10 Housing 11 Housing hole 12 First plunger 13 Return spring 14 Ratchet 15 Rack 16 Ratchet locking mechanism 17 Oil supply port 18 Oil chamber 19 Check ball mechanism 20 Actuator 27 Actuator Tube 28 Second plunger 29 Spring 30 Flange 31 Slit

Claims (2)

A ratchet type hydraulic tensioner used to apply appropriate tension to a timing chain that transmits rotation between a crankshaft side sprocket of an engine and a camshaft side sprocket paired on an intake side and an exhaust side,
A first plunger fitted in the housing hole formed in the housing so as to be reciprocally movable in the front-rear direction;
First biasing means for biasing the first plunger in the forward direction so as to protrude from the housing toward the timing chain on which the first plunger travels;
A check ball mechanism that allows oil fed from an oil supply port to flow into an oil chamber provided inside the first plunger to prevent backflow;
An operating body inserted in the oil chamber in front of the check ball mechanism and operated by hydraulic pressure,
The operating body is:
A working cylinder whose rear end is fixed to the bottom of the accommodation hole and whose front end faces the oil chamber;
A second plunger fitted in the operation cylinder so as to be reciprocally movable in the front-rear direction;
When the oil pressure is not applied to the oil chamber, the second plunger is set to the first posture to press the first plunger, and when the oil pressure is applied to the oil chamber, the second plunger is pushed into the working cylinder. The ratchet type hydraulic tensioner includes switching means for adopting the posture. The ratchet hydraulic tensioner according to claim 1,
The switching means is
Second urging means disposed in a space formed between the operating cylinder and the second plunger and urges the second plunger in the forward direction so as to press the first plunger. When,
A slit that opens in a flange that partitions the accommodation hole and the check ball mechanism at a peripheral edge of a rear end portion of the working cylinder, and communicates the accommodation hole and the check ball mechanism;
When the hydraulic pressure is not applied to the oil chamber, the second plunger is set to the first posture by the biasing force of the second biasing means, and when the hydraulic pressure is applied to the oil chamber, the second biasing force is applied. A ratchet hydraulic tensioner characterized in that the second plunger is in the second posture against the urging force of the urging means.

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