JP2009168218A - Hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic tensioner which can prevent a vibration of a mounting part, a thrash of a plunger or an endlessness transmission element, an allophone, or the like by swiftly starting up a fluid pressure at the time of start so as to suppress invasion of air into a hydraulic chamber due to leakage of a hydraulic oil during engine shutdown. <P>SOLUTION: In the hydraulic tensioner comprising a housing 11 having a supply passage 11a supplied with a pressurized liquid and a plunger 13 slidably held by the housing 11 so as to form the hydraulic chamber 12 with the housing 11, and adding a biassing force so as to adjust a tension between specific traveling intervals of a chain rolled between a crankshaft and a cam shaft by the plunger 13, a liquid absorbing retaining member 51 is stored which absorbs a liquid to expand when it is immersed in the liquid within the hydraulic chamber 12 and also retains a state of absorbing the liquid to expand when the pressure of the liquid supplied from the supply passage 11a is decreased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic tensioner, and more particularly to a hydraulic tensioner in which a plunger is slidably provided so as to form a hydraulic pressure chamber in a housing having a hydraulic pressure supply passage.

  In an internal combustion engine, an endless transmission element such as a timing chain that transmits rotational power from a crankshaft to a camshaft of a valve mechanism is required to operate at an accurate timing without slack. A tensioner is used that absorbs a change in chain tension due to a change or a change in engine speed, or a decrease in chain tension due to secular change, and keeps the tension within an appropriate range. In addition, the hydraulic pressure (hydraulic pressure) from the oil pump that circulates the lubricating oil of the internal combustion engine applies a pressing force that applies tension to the chain, and at the time of sudden fluctuations in tension, leakage from the plunger sliding part and valve gap part, etc. A hydraulic tensioner that is used to generate a hydraulic damper effect is often used.

  Conventionally, as this type of hydraulic tensioner, for example, a plunger is slidably held in a housing having an oil supply passage, and a hydraulic pressure chamber communicating with the oil supply passage is formed between them. Assist that compensates for the lack of hydraulic damper force when starting the engine separately from the spring for returning the plunger to the outside in the hydraulic chamber, while applying a pressing force to maintain the tension of the transmission element One provided with a spring is known (for example, see Patent Document 1).

  In addition, a cup-shaped member with a check valve and a piston are arranged opposite to each other in the cylinder. When the piston is extended, both the cup-shaped member and the check valve opposed to the piston are opened. Both stop valves are closed, and an oil absorber is provided in the upper liquid chamber on the back side of the cup-shaped member so that the hydraulic oil level is always buried. What prevents the fall of a damper effect by preventing is known (for example, refer to patent documents 2).

In addition, filling the hydraulic chamber between the housing and plunger to reduce the volume of the hydraulic chamber, shorten the hydraulic oil filling time when starting the engine, and exert a hydraulic damper effect immediately after starting Is also known (see, for example, Patent Documents 3 and 4).
JP 2007-285341 A Japanese Utility Model Publication No. 06-14599 JP 2007-16953 A JP 2007-255578 A

  However, with the conventional hydraulic tensioner as described above, the posture of the plunger of the hydraulic tensioner is not stable until the hydraulic pressure rises at the start of the engine, and it is possible to reliably prevent abnormal noise due to flapping of the hydraulic tensioner I couldn't.

  In other words, since a certain clearance is set in the sliding portion of the plunger or the like in order to exert the required oil damper effect during operation, the hydraulic oil in the hydraulic pressure chamber gradually gets into the engine while the engine is stopped. In order to leak into the interior, the hydraulic chamber is often in a balanced state with two phases of oil and air at the time of starting. For this reason, the presence of air in the hydraulic chamber when the engine is started prevents the hydraulic pressure from increasing quickly, and the hydraulic tensioner's pressing force cannot be sufficiently obtained. There is a problem that the hitting sound is generated between the chain and the slipper that is pressed by the operation force from the hydraulic tensioner while guiding the chain, and vibration is generated in the mounting portion of the hydraulic tensioner. It was happening.

  Also, until the hydraulic pressure reaches a predetermined level at the start of the engine, not only does the vibration of the hydraulic tensioner mounting portion increase due to the presence of air inside the hydraulic tensioner, but also immediately after the hydraulic pressure reaches the predetermined level. When the air in the oil passage enters the hydraulic tensioner, it is difficult for the air inside the hydraulic tensioner to escape and vibration of the hydraulic tensioner mounting portion occurs.

  The present invention has been made in order to solve the above-described conventional problems, and prevents hydraulic oil from escaping from the hydraulic pressure chamber while the engine is stopped and the accompanying air intrusion, thereby reducing the hydraulic pressure when starting the internal combustion engine. An object of the present invention is to provide a hydraulic tensioner capable of quickly raising the hydraulic pressure in the room and preventing vibration of the tensioner mounting portion, flapping of the plunger and the endless transmission element, abnormal noise, and the like.

  In order to achieve the above object, the hydraulic tensioner according to the present invention is slidable on the housing to form a hydraulic chamber together with a housing having a supply passage through which pressurized liquid is supplied and the housing. A plunger held by the plunger, and the plunger applies a pressing force to adjust the tension of the endless transmission element in a specific movement section of the endless transmission element wound between the drive shaft and the driven shaft. In the hydraulic tensioner, the liquid absorbs and expands when immersed in the liquid in the hydraulic chamber, and absorbs and expands the liquid when the pressure of the liquid supplied from the supply passage decreases. The liquid absorption holding member that holds the state is housed in the hydraulic chamber.

  With this configuration, when the liquid absorption holding member in the hydraulic pressure chamber is immersed in the liquid, the liquid absorption holding member absorbs the liquid and expands and absorbs the liquid even when the pressure of the liquid supplied from the supply passage decreases. Since the expanded state is maintained, it is difficult for hydraulic oil to escape from the inside of the hydraulic pressure chamber when the internal combustion engine is stopped, and air intrusion can be suppressed. Therefore, a hydraulic tensioner that can quickly start up the hydraulic pressure in the hydraulic chamber when starting the internal combustion engine, and can prevent vibration of the mounting portion of the tensioner, flapping of the plunger and the endless transmission element, abnormal noise, etc. Become.

  It is preferable that the endless transmission element receives the pressing force from the hydraulic tensioner in the moving section where the tension is smaller than the other moving sections and is on the slack side during the transmission rotation of the endless transmission element.

  In the hydraulic tensioner having the configuration of (1), (2) an elastic member for biasing the plunger toward the outer side of the housing is interposed between the housing and the plunger, and the supply passage It is preferable that when the pressure of the liquid supplied from is lowered, the plunger receiving the urging force from the elastic member applies the pressing force to the specific moving section of the endless transmission element.

  With this configuration, even when the pressure of the liquid in the hydraulic chamber is reduced, the plunger can be applied with a pressing force that provides an appropriate winding posture from the plunger to the endless transmission element side, and the endless transmission element flutters at the start of the internal combustion engine. Can be effectively suppressed. In a state where the pressure of the liquid in the hydraulic pressure chamber is lowered, it is preferable that the liquid absorption holding member is somewhat compressed by the plunger to promote absorption and expansion of the liquid absorption holding member when supplying the hydraulic pressure.

  In the hydraulic tensioner having the configurations of (1) and (2) above, (3) the liquid absorption holding member may be made of porous rubber or resin.

  With this configuration, the liquid absorption holding member can easily absorb the liquid, and if a material that easily swells is used as the material, the liquid holding performance is enhanced. In addition, one liquid absorbing / holding member made of porous rubber or resin may be accommodated in the hydraulic pressure chamber, but a plurality of liquid absorbing / holding members stacked in multiple layers, or the hydraulic pressure chamber is filled. Many granular liquid absorption holding members may be accommodated in the hydraulic chamber.

  In the hydraulic tensioner having the configuration of (3), it is more preferable that (4) the liquid absorption holding member is made of foamed rubber or foamed resin having an open cell structure.

  With this configuration, the liquid absorption holding member is easily compressed and has a high liquid absorption rate. The open cell structure referred to here is, for example, a continuous bubble in which the liquid absorption rate obtained by dividing the mass difference between before and after being immersed in the liquid and absorbing the liquid by the mass before the liquid absorption exceeds 5%, for example. This is a state in which (pores) are increased. The liquid absorption rate of the liquid absorption holding member is preferably 15% or more, for example.

  The liquid absorption holding member is not limited to a foam having an open cell structure, but is suitable for absorption and holding of liquid such as oil, and is suitable for absorption / expansion due to spontaneous expansion due to absorption or a decrease in compression amount. It may be a non-woven fabric, a cotton-like fabric, a flexible fabric or a mesh-like fabric wound in a spiral.

  In the hydraulic tensioner having the configurations of (1) to (4) above, (5) the endless transmission element wound between the drive shaft and the driven shaft is provided between the crankshaft and the camshaft of the internal combustion engine. A chain wound between is preferred.

  With this configuration, oil that is also used for lubrication and cooling of the chain can be absorbed by the liquid absorption holding member in the hydraulic chamber to expand the liquid absorption holding member, and the hydraulic pressure can be raised immediately when the internal combustion engine is started. Further, vibration of the tensioner mounting portion, flapping of the plunger or chain, abnormal noise, and the like can be prevented.

  In the hydraulic tensioner having the configuration of (1) to (5) above, (6) the movement of the plunger is suppressed between the housing and the plunger, and the set value is not less than a preset value set in the plunger. A movement restriction mechanism that allows movement of the plunger when a force is applied is provided, and the movement restriction mechanism can regulate movement of the plunger in a state where the liquid absorption holding member is compressed by the plunger. Good.

  With this configuration, the plunger is held by the movement restriction mechanism in a state where the liquid absorption holding member is compressed, and can be handled in a state in which the plunger is contracted into the housing before assembly, and the plunger is pushed out by supplying hydraulic pressure. Sometimes the compressive force applied to the liquid absorption holding member is also reduced, and the expansion of the liquid absorption holding member is promoted.

  According to the present invention, when the liquid absorption holding member provided in the hydraulic pressure chamber absorbs and expands the liquid when immersed in the liquid, the pressure of the liquid supplied from the supply passage decreases. Since the configuration is such that the liquid is absorbed and expanded, the hydraulic oil is difficult to escape from the inside of the hydraulic pressure chamber when the internal combustion engine is stopped, and the intrusion of air can be suppressed. To provide a hydraulic tensioner that can quickly start up the hydraulic pressure in the hydraulic chamber at the start and prevent vibration of the hydraulic tensioner mounting part, flapping of the plunger and endless transmission elements, abnormal noise, etc. it can.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a front cross-sectional view of a hydraulic tensioner according to an embodiment of the present invention, FIG. 2 is a schematic front view of an essential part of an internal combustion engine including the hydraulic tensioner according to an embodiment, and FIG. It is a front sectional view at the time of plunger contraction of a hydraulic tensioner concerning one embodiment.

  First, the configuration will be described.

  As shown in FIGS. 1 and 2, the hydraulic tensioner 10 of the present embodiment includes a housing 11 and a plunger 13 having a circular cross section that is slidably held in the housing 11 so as to form a hydraulic chamber 12 together with the housing 11. And.

  The housing 11 has, on its inner side, a supply passage 11a for supplying pressurized oil (liquid; for example, engine oil) and a plunger storage hole 11b for storing the plunger 13 so as to be slidable. In addition, mounting holes 11e and 11f supported by an engine block (not shown) of the engine 1 (internal combustion engine) are provided on the outer side.

  The plunger 13 has a concave portion 13 a that faces the inner surface 11 c side of the plunger housing hole 11 b and a substantially cylindrical skirt portion 13 b that surrounds the concave portion 13 a, and a plunger between the housing 11 and the plunger 13 A compression coil spring 14 (elastic member) for biasing 13 toward the outer side of the housing 11 is interposed. In addition, a rack portion 13m including a plurality of teeth T arranged at a predetermined pitch in the axial direction of the plunger 13 is provided on the outer peripheral portion of the plunger 13.

  As shown in FIG. 2, the hydraulic tensioner 10 includes a crankshaft 31 (drive shaft) disposed at the lower portion of the engine 1 and intake and exhaust camshafts 32 and 33 disposed at the upper portion of the engine 1 by a plunger 13. A pressing force is applied to the upper end portion 35a of the slipper 35 close to a specific moving section of the chain 34 (endless transmission element) wound around the (driven shaft) toward the chain 34 side. ing.

  The slipper 35 is supported at the lower end 35b in FIG. 2 so as to be swingable in the left-right direction in the figure with respect to the engine block, and the upper end 35a is moved to the right in the figure by the plunger 13 of the hydraulic tensioner 10. When pressed, the chain 34 can be guided by the link portion to eliminate the slackness of the chain 34 or to increase the tension of the chain 34.

  More specifically, pressurized oil is supplied to the supply passage 11a of the housing 11 from an oil pump (not shown) that circulates oil as the lubricating oil during operation of the engine 1. The oil pressure Ps is supplied from the supply passage 11 a to the hydraulic chamber 12 and is received by the plunger 13.

  The inner end of the supply passage 11a that opens to the hydraulic pressure chamber 12 allows oil to flow from the supply passage 11a to the hydraulic pressure chamber 12 side, while from the hydraulic pressure chamber 12 side to the supply passage 11a side. A check valve 36 is provided to block the oil flow. The check valve 36 includes a spherical valve body 36a, a substantially cylindrical valve seat portion 36b on which the spherical valve body 36a is seated, and a cap-like shape that prevents the spherical valve body 36a from dropping off from the vicinity of the valve seat portion 36b. And a valve guide 36c. The valve guide 36c is formed with a plurality of slit-shaped or circular communication holes 36d which are sufficiently smaller than the diameter of the spherical valve body 36a, and the supply passage 11a side and the hydraulic pressure chamber 12 side are formed by these communication holes 36d. And communicate with each other.

  When pressurized oil is supplied to the hydraulic chamber 12 through the check valve 36, the plunger 13 is pushed out by the hydraulic pressure Ps so as to increase the volume of the hydraulic chamber 12 and through the slipper 35. A pressing force can be applied to a specific movement section of the chain 34. Further, the plunger 13 applies a pressing force to a specific moving section of the chain 34 via the slipper 35 while receiving an urging force from the compression coil spring 14 when the hydraulic pressure of the oil supplied from the supply passage 11a decreases. It is like that. The specific movement section referred to here is a movement section that has a smaller tension than the other movement sections and is on the slack side during transmission rotation of the chain 34.

  When the tension of the chain 34 is suddenly changed due to the fluctuation of the engine speed, the hydraulic tensioner 10 leaks from the sliding gap portion between the plunger 13 and the housing 11 against the sudden increase of the reaction force from the slipper 35. It has a structure that produces a hydraulic damper effect. Further, the hydraulic tensioner 10 pushes the plunger 13 to suppress the slackness of the chain 34 when the reaction force from the slipper 35 decreases, and has a function of keeping the tension of the chain 34 within an appropriate range. is doing.

  Further, the movement of the plunger 13 is suppressed between the housing 11 and the plunger 13 and allows a certain amount of movement of the plunger 13 when a force greater than a preset value is applied to the plunger 13. A limiting mechanism 40 is provided.

  The movement restricting mechanism 40 includes a cam 41 that is rotatably supported by the housing 11 at a central portion 41c, and a compression coil spring 42 that is contracted between the housing 11 and the cam 41. Is urged to one side in the rotational direction by the compression coil spring 42 so as to press the pair of engaging claws 41a and 41b against the rack portion 13m of the plunger 13. The pair of engaging claws 41 a and 41 b are formed on one end side of the cam 41, and the compression coil spring 42 is engaged on the other end side of the cam 41.

  When a force greater than a preset value set on the plunger 13, for example, an oil pressure based on a hydraulic pressure above a certain level from the oil pump, acts on the plunger 13 from the slipper 35 side according to the tension of the chain 13. Force acts in the opposite direction to the oil pressure. When the oil pressure exceeds the reaction force and the force exceeding the reaction force is equal to or greater than the set value, the plunger 13 is pushed back in the clockwise direction in FIG. 1 against the urging force of the compression coil spring 42. (See the cam 41 and the plunger 13 indicated by phantom lines in FIG. 1), and the plunger 13 presses the slipper 35 so as to increase the tension of the chain 34. On the other hand, when the tension of the chain 34 increases, the shape of the cam 41 is set so that the retreat amount of the plunger 13 is limited within a certain range by the cam 41 engaged with the rack portion 13m. Further, as described above, when the plunger 13 is pushed back in the clockwise direction in FIG. 1 against the urging force of the compression coil spring 42, the tension of the chain 34 increases. A certain amount shifted by one tooth T of the portion 13m is allowed. That is, the movement limiting mechanism 40 allows a certain amount of movement of the plunger 13 when a force greater than a preset value is applied to the plunger 13.

  Such a hydraulic tensioner 10 generates a reaction force from the slipper 35 according to the urging force of the compression coil spring 14 to the plunger 13, the hydraulic pressure based on the hydraulic pressure supplied to the hydraulic chamber 12, and the tension of the chain 34. While being received, the movement restriction mechanism 40 appropriately suppresses the movement to be mainly on the slack side of the chain 34. As a result, the hydraulic tensioner 10 not only has a sudden change in the tension of the chain 34 due to a change in the engine speed, but also a change in the tension of the chain 34 due to a temperature change of the engine 1 and a decrease in the tension of the chain 34 due to a secular change. Absorbs and keeps its tension within the proper range.

  On the other hand, the oil pressure chamber 12 absorbs oil when it is immersed in the oil in the oil pressure chamber 12 and expands, and when the hydraulic pressure (oil pressure) supplied from the supply passage 11a decreases. A liquid absorption holding member 51 that holds the expanded state by absorbing oil is housed.

  The liquid absorbing and holding member 51 has a free-form volume (including open cells) larger than the storage volume so that the plunger 13 is slightly compressed even when the oil pressure in the hydraulic chamber 12 is reduced. So that the oil is absorbed not only by the absorption of the oil by the liquid absorption holding member 51 and the expansion accompanying it but also by the elastic recovery expansion when supplying the hydraulic pressure to the hydraulic chamber 12. It has become.

  Further, even when the plunger 13 protrudes in the most extending direction within the movable range, the liquid absorption holding member 51 occupies most of the volume in the hydraulic pressure chamber 12.

  The liquid absorption holding member 51 is made of a resin such as porous rubber or urethane, and is, for example, foamed rubber or foamed resin having an open cell structure. The open cell structure referred to here is, for example, a value obtained by dividing the mass difference between the liquid absorption holding member 51 before and after the liquid absorption holding member 51 is immersed in the oil to absorb the oil by the mass before the liquid absorption. Is an oil absorption rate, the oil absorption rate is a constant value, for example, a state where there are many continuous bubbles (pores) exceeding 5%, and the liquid absorption holding member 51 in the present embodiment. The oil absorptivity is 15% or more, for example.

  Although this liquid absorption holding member 51 has elasticity like rubber, as shown in FIG. 3, when the plunger 13 is retracted to a position where it is retracted to the innermost back side, the liquid absorption holding member 51 is greatly compressed by the plunger 13. Even in such a state, the repulsion force against the compression is sufficiently flexible (low elasticity) and low repulsion performance so that the force of the set value for canceling the movement restriction by the movement restriction mechanism 40 becomes small. It is made of a material that can keep the amount of permanent strain accompanying the volume change small.

  The liquid absorption holding member 51 may be any member that is suitable for absorption and retention of oil and suitable for absorption and expansion accompanying spontaneous expansion due to absorption and a decrease in the compression amount from the plunger 13. For example, a large number of pores having a diameter larger than that of the bubbles may be formed in the foam material in parallel. Further, the liquid absorption holding member 51 may swell when oil penetrates into the material itself, or does not soak into the material itself, and absorbs oil into open cells or pores. (Including those accompanying expansion) and expansion may occur. Further, when the hydraulic tensioner 10 is in use, the movement of the plunger 13 toward the backward (shrinkage) side is limited within a certain range, and the plunger 13 is moved in the extension direction (extension direction of the compression coil spring 14) larger than that. Since the moving amount is usually as small as about several millimeters, the expanded liquid absorption holding member 51 may enter the gap between the wires of the compression coil spring 14 and be held in the compression coil spring 14.

  In FIG. 2, the chain 34 has a fixed guide in each of a movement section between the camshafts 32 and 33 and a movement section from the camshaft 33 to the crankshaft 31 in addition to the movement section guided by the slipper 35. The units 25 and 26 are guided by link portions constituting the chain 34, respectively.

  Further, the engine shown in FIG. 2 has a hydraulic variable valve timing mechanism (VVT) as a variable valve control device that continuously and variably controls the valve timing according to the operating state. Although the details of the valve timing mechanism are not shown, chain sprockets 22a and 23a driven by a crankshaft 31 via a chain 34 are mounted on one end of each of the camshafts 32 and 33 while a vane rotor having a plurality of vanes is mounted. The vane rotor is rotatably accommodated by the mounted VVT housings 22 and 23. In this case, there is an advance oil chamber (hereinafter referred to as an advance chamber) and a retard oil chamber (hereinafter referred to as a retard chamber) opposed to each other in the rotational direction across the vane between the vane rotor and the housing. The valve timing is changed to the advanced side by discharging oil from the retarded chamber while supplying oil to the advanced chamber and the retarded chamber. The valve timing is changed to the retard side by discharging the oil from the advance chamber while supplying oil to the chamber.

  Next, the operation will be described.

  In the hydraulic tensioner of the present embodiment configured as described above, when the liquid absorption holding member 51 in the hydraulic chamber 12 is immersed in oil, it absorbs oil and expands. This is maintained even when the engine stops when the pressure of the oil supplied from the supply passage 11a decreases. Therefore, even if the engine 1 is in a stopped state, it is difficult for hydraulic oil to escape from the inside of the hydraulic pressure chamber 12 and air intrusion into the hydraulic pressure chamber 12 can be suppressed.

  Next, when the oil pump is activated by starting the engine 1, the engine speed NE rises, for example, as shown in FIG.

  At this time, in the case of the comparative example indicated by the dotted line in FIG. 4B (conventional product without the liquid absorption holding member 51), the hydraulic pressure Ps ′ in the hydraulic chamber 12 reaches a predetermined level from the start of the engine. In the meantime, the presence of air inside the hydraulic tensioner not only increases the vibration of the hydraulic tensioner mounting part, but also immediately after the hydraulic pressure reaches a predetermined level, the air in the oil passage enters the hydraulic tensioner. The penetration of the hydraulic tensioner mounting portion caused the penetration.

  On the other hand, in the case of the present embodiment indicated by a solid line in FIG. 4B, the hydraulic pressure in the hydraulic chamber 12 starts from a very early stage compared to the comparative example (however, it has a relatively steep slope compared to the comparative example). Not)) will stand up. Accordingly, there is no air in the hydraulic tensioner enough to cause vibration of the hydraulic tensioner mounting portion, and even if air in the oil passage enters the hydraulic pressure chamber 12 immediately after that, the liquid tension is retained. Since the air does not easily enter the member 51, the excess air hardly remains and the fluid pressure stabilizes early.

  Therefore, the posture of the plunger 13 becomes unstable due to insufficient oil pressure, and the mounting portion of the hydraulic tensioner 10 can be prevented from vibrating and the plunger 13 and the chain 34 fluttering. Generation of abnormal noise around the chain can be prevented.

  Further, in the present embodiment, even when the oil pressure in the hydraulic chamber 12 decreases, the compression coil spring 14 or the movement restriction mechanism 40 applies a pressing force that provides an appropriate winding posture from the plunger 13 to the chain 34 side. It is possible to effectively suppress the flapping of the chain when the engine is started.

  Furthermore, since the porous liquid absorption holding member 51 is easy to absorb oil and is configured to expand at the time of absorption, the oil holding performance is high, and hydraulic oil is discharged from the hydraulic chamber 12 and accompanying this. Intrusion of air into the hydraulic chamber 12 can be sufficiently suppressed.

  In particular, in the present embodiment, since the liquid absorption holding member 51 is composed of foamed rubber or foamed resin having an open-cell structure with low elasticity and low resilience, the liquid absorption holding member is easy to compress and has a high oil absorption rate. 51. Even if a material that easily swells is used as the material of the liquid absorption holding member 51, the oil holding performance is improved.

  Furthermore, in this embodiment, the oil used for lubrication and cooling of the chain 34 is absorbed by the liquid absorption holding member 51 in the hydraulic pressure chamber 12 to expand the liquid absorption holding member 51, and the hydraulic pressure chamber is started when the engine is started. Since the hydraulic pressure in 12 can be raised immediately, vibration of the mounting portion of the hydraulic tensioner 10, flapping of the plunger 13 and the chain 34, abnormal noise, and the like can be prevented.

  Further, the plunger 13 is held by the movement restriction mechanism 40 in a state where the liquid absorption holding member 51 is compressed, and the plunger 13 can be handled in a state where the plunger 13 is contracted in the housing 11 before the hydraulic tensioner 10 is assembled. In addition, the compressive force applied to the liquid absorption holding member 51 when the plunger 13 is pushed out by supplying hydraulic pressure is reduced, and the expansion of the liquid absorption holding member 51 is promoted.

  Thus, in the hydraulic tensioner of the present embodiment, when the liquid absorption holding member 51 provided in the hydraulic chamber 12 is immersed in the oil, it absorbs the oil and expands, while the supply passage 11a. When the pressure of the oil supplied from the engine is reduced, the oil is absorbed and expanded to be maintained, so that it is difficult for the hydraulic oil to escape from the hydraulic chamber 12 when the engine 1 is stopped. Intrusion of air into the hydraulic chamber 12 can be suppressed, the hydraulic pressure in the hydraulic chamber 12 can be raised immediately when the engine 1 is started, the vibration of the hydraulic tensioner mounting portion, the plunger, A hydraulic tensioner capable of preventing flapping of the endless transmission element, abnormal noise, and the like can be provided.

  In the above-described embodiment, the endless transmission element wound between the drive shaft and the driven shaft is a chain wound between the crankshaft of the engine 1 and the camshaft. However, the endless transmission element is A metal timing belt may be used instead of a chain.

  Furthermore, one liquid absorbing / holding member made of rubber or resin having porosity may be accommodated in the hydraulic chamber, but may be divided into a plurality of parts.

  For example, as shown in FIG. 5A, a plurality of liquid absorption holding members 61a, 61b, 61c, 61d, 61e, 61f, 61g, 61h, 61i, and 61j stacked in multiple layers are formed as a whole in the above embodiment. The liquid absorption holding member 61 may be substantially the same as the liquid absorption holding member 51. The liquid absorption holding member 61 is not limited to foamed rubber or foamed resin having a continuous foam structure, A thing, a cotton-like thing, and a net-like thing may be sufficient.

  Also, as shown in FIG. 5B, flexible foamed rubber or foamed resin tubes 71a, 71b, 71c, 71d, 71e, 71f, 71g, 71h (or spirally) laminated in the radial direction inside and outside. The liquid absorption holding member 71 may be made of a rolled flexible foam rubber or foamed resin sheet, and the tubes 71a to 71h may be non-woven fabrics or flexible nets.

  Further, as shown in FIG. 5C, a large number of granular liquid absorption holding members 81 that fill the hydraulic chamber 12 may be stored so as to substantially fill the hydraulic chamber 12.

  In any of the above-described cases, the liquid supplied into the hydraulic chamber 12 is oil, but in the present invention, the liquid supplied into the hydraulic chamber is a liquid other than oil (incompressible fluid). It may be. Further, a backflow prevention valve such as the check valve 36 and an elastic member such as the compression coil spring 14 are not necessarily required.

  As described above, the hydraulic tensioner according to the present invention is supplied from the supply passage while the liquid absorption holding member provided in the hydraulic chamber absorbs the liquid and expands when immersed in the liquid. When the pressure of the liquid is reduced, it is configured to maintain the expanded state by absorbing the liquid, and it is difficult for hydraulic oil to escape from the inside of the hydraulic pressure chamber when the internal combustion engine is stopped, and air intrusion can be suppressed. As a result, when the internal combustion engine is started, the hydraulic pressure in the hydraulic chamber can be quickly raised, and vibrations of the mounting portion of the hydraulic tensioner, flapping of the plunger and endless transmission elements, noise, etc. can be prevented. The hydraulic tensioner is capable of providing a hydraulic tensioner, and in particular, a hydraulic tensioner, particularly a hydraulic pressure slidably provided with a plunger so as to form a hydraulic pressure chamber in a housing having a supply passage. It is useful in conditioner in general.

It is front sectional drawing of the hydraulic tensioner which concerns on one Embodiment of this invention. It is a principal part schematic front view of the internal combustion engine provided with the hydraulic tensioner which concerns on one Embodiment. It is a front sectional view at the time of plunger contraction of a hydraulic tensioner concerning one embodiment. It is a characteristic view which shows the rise characteristic of the hydraulic pressure at the time of engine starting in the hydraulic tensioner concerning one embodiment compared with the former, and the figure (a) shows change of the engine speed immediately after engine starting (the figure ( b) shows the oil pressure change in the hydraulic chamber immediately after the engine is started. It is a figure which shows the deformation | transformation aspect of the liquid absorption holding member with which the hydraulic tensioner which concerns on one Embodiment of this invention is equipped, The figure (a) is what made the multilayer in the axial direction of the plunger, The figure (b) The plunger in the radial direction is shown in FIG. 5C, and a plurality of granular liquid absorbing and holding members are shown.

Explanation of symbols

1 engine (internal combustion engine)
DESCRIPTION OF SYMBOLS 10 Hydraulic tensioner 11 Housing 11a Supply passage 11b Plunger accommodation hole 11c Inner surface 11e, 11f Mounting hole 12 Hydraulic chamber 13 Plunger 13a Recessed part 13b Skirt part 13m Rack part 14 Compression coil spring (elastic member)
22, 23 VVT housing 25, 26 Fixed guide unit 31 Crankshaft 32, 33 Camshaft 34 Chain (endless transmission element)
35 Slipper 35a Upper end portion 35b Lower end portion 36 Check valve 40 Movement limiting mechanism 41 Cam 41a, 41b Engaging claw portion 42 Compression coil spring 51, 61, 71, 81 Liquid absorption holding member T tooth

Claims (6)

A housing having a supply passage through which pressurized liquid is supplied, and a plunger slidably held in the housing so as to form a hydraulic chamber together with the housing. In the hydraulic tensioner that applies a pressing force to adjust the tension of the endless transmission element in a specific movement section of the endless transmission element wound between the drive shafts,
When immersed in the liquid in the hydraulic chamber, the liquid absorbs and expands, and when the pressure of the liquid supplied from the supply passage decreases, the liquid is absorbed and expanded. A hydraulic tensioner, wherein the liquid absorbing and holding member is housed in the hydraulic chamber. Between the housing and the plunger, an elastic member for biasing the plunger toward the outer side of the housing is interposed,
When the pressure of the liquid supplied from the supply passage decreases, the plunger that receives the urging force from the elastic member applies the pressing force to the specific moving section of the endless transmission element. The hydraulic tensioner according to claim 1.   The hydraulic tensioner according to claim 1 or 2, wherein the liquid absorption holding member is made of rubber or resin having porosity.   4. The hydraulic tensioner according to claim 3, wherein the liquid absorption holding member is made of foamed rubber or foamed resin having an open cell structure.   5. The endless transmission element wound between the drive shaft and the driven shaft is a chain wound between a crankshaft and a camshaft of an internal combustion engine. The hydraulic tensioner according to claim 1. Between the housing and the plunger, there is provided a movement limiting mechanism that suppresses the movement of the plunger and allows the plunger to move when a force greater than a preset value is applied to the plunger.
6. The method according to claim 1, wherein the movement restriction mechanism can regulate movement of the plunger in a state where the liquid absorption holding member is compressed by the plunger. The hydraulic tensioner described.

Images