JP5316927B2 - Chain tensioner - Google Patents

Description

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

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

  As a chain tensioner incorporated in this tension adjusting device, a plunger is slidably inserted into a bottomed cylindrical housing with one end open, and the plunger is a bottomed cylindrical shape with an insertion end into the housing open, An oil supply passage for introducing hydraulic oil is provided in a pressure chamber surrounded by the housing and the plunger, and a check valve for preventing a backflow of the hydraulic oil from the pressure chamber to the oil supply passage is provided at the outlet of the oil supply passage. Is urged in a direction protruding from the housing by a return spring, and the chain is pressed by the protruding end of the plunger from the housing (Patent Documents 1 and 2).

  When the chain tension increases during engine operation, these chain tensioners move in the direction in which the plunger is pushed into the housing (hereinafter referred to as the “pushing direction”) due to the chain tension, and absorb the chain tension. . At this time, the hydraulic oil in the pressure chamber flows out through a leak gap between the sliding surface of the plunger and the housing, the flow rate of the hydraulic oil is limited, and a damper action is generated, so that the plunger moves slowly.

  On the other hand, when the chain tension is reduced during engine operation, the plunger moves in the direction protruding from the housing (hereinafter referred to as “projection direction”) by the urging force of the return spring, and absorbs the slackness of the chain. At this time, since the hydraulic oil supplied from the oil pump flows into the pressure chamber through the oil supply passage, the plunger moves quickly.

  Further, in the chain tensioner of Patent Document 1, when the secondary side escape passage connected to the pressure chamber is provided in the housing, and the pressure in the pressure chamber becomes larger than the preset pressure in the secondary side escape passage. A secondary-side relief valve that opens is installed.

  The chain tensioner of Patent Document 2 is also provided with a secondary side escape passage connected to the pressure chamber in the plunger, and is opened when the pressure in the pressure chamber becomes higher than a preset pressure in the secondary side escape passage. Secondary side relief valve is installed.

Therefore, in these chain tensioners, when the chain is rapidly tensioned and the pressure in the pressure chamber increases, the secondary side relief valve opens to release the hydraulic oil in the pressure chamber, and as a result, the plunger moves in the pushing direction. So the chain will not be over tensioned.
JP 2004-176821 A JP 2006-17214 A

  By the way, the temperature of the hydraulic oil supplied from the oil pump is usually in a range from room temperature to about 100 ° C., but may be 0 ° C. or less in a cold region or a low temperature environment in winter. At this time, since the viscosity of the hydraulic oil increases, the pressure of the hydraulic oil supplied from the oil pump increases, and the pressure in the pressure chamber into which the hydraulic oil flows increases, and the chain may become over-tensioned. It was.

  In order to prevent over-tension in this low temperature environment, it is conceivable that the hydraulic oil in the pressure chamber is released by the secondary side relief valve described above, but the secondary side relief valve is opened and the hydraulic oil in the pressure chamber is released. Even if it escapes, high-pressure hydraulic oil continues to flow from the oil supply passage into the pressure chamber, so it is difficult to prevent an increase in pressure in the pressure chamber.

  The problem to be solved by the present invention is to provide a chain tensioner capable of preventing chain over tension in a low temperature environment.

  In order to solve the above problems, a plunger is slidably inserted into a bottomed cylindrical housing with one end open, and the plunger has a bottomed cylindrical shape with an insertion end into the housing open, An oil supply passage for introducing hydraulic oil is provided in the pressure chamber surrounded by the plunger, and a check valve for preventing backflow of the hydraulic oil from the pressure chamber to the oil supply passage is provided at the outlet of the oil supply passage. A chain tensioner provided with a return spring that urges in the protruding direction and presses the chain with a protruding end from the housing of the plunger, and is provided with a primary side relief passage that branches off from the middle of the oil supply passage. A primary relief valve that opens in the relief passage when the pressure in the oil supply passage becomes larger than a preset pressure. Incorporating.

  The chain tensioner further includes a secondary-side escape passage connected to the pressure chamber, and the secondary-side relief passage is opened when the pressure in the pressure chamber becomes higher than a preset pressure. A side relief valve can be incorporated.

Further, this chain tensioner can have the following configuration.
1) A screw rod having an external thread that engages with an internal thread formed on the inner periphery of the housing is provided on the outer periphery. The flank angle of the side flank is formed in a sawtooth shape larger than the flank angle of the play side flank.
2) A register ring that elastically tightens the outer periphery of the plunger is housed in a housing groove formed on the inner periphery of the housing, and the register ring is formed on the outer periphery of the plunger at a constant interval in the axial direction. A tapered surface that engages with a circumferential groove and allows the movement of the plunger by expanding the diameter of the register ring when the plunger is pressed in a direction protruding from the housing in each circumferential groove, and the plunger A stopper surface is provided that locks the register ring to prevent the plunger from moving when it is pushed in the direction of pushing it into the housing.

  Further, when a flange portion is provided on the outer periphery of the housing, the flange portion being fixed to the outer surface of the engine cover in a state where the housing is fitted in the tensioner mounting hole of the engine cover, the flange portion is provided on the mating surface with respect to the engine cover. A flat surface provided on the outer periphery of the housing by opening the outlet of the primary side escape passage and forming an oil passage groove from the outlet of the primary side escape passage to the outer periphery of the housing on the mating surface of the flange portion with the engine cover And an oil passage that communicates with the engine cover through a gap formed between the inner periphery of the tensioner mounting hole.

  Furthermore, when the primary side escape passage is composed of a radial hole extending from the outer periphery of the flange portion to the oil supply passage, and an axial hole extending from the mating surface of the flange portion to the engine cover to the radial hole, The primary relief valve can be inserted into the radial hole from the outer periphery of the flange portion and fixed with a set screw.

The chain tensioner is preferably added with the following configuration.
1) The check valve has a spherical valve body that opens and closes a valve hole, and the valve body is a ceramic ball or a steel ball coated with ceramic coating.
2) A diamond-like carbon film is formed on the contact surface of the valve body of the check valve.

  In the chain tensioner of the present invention, when the pressure in the oil supply passage becomes high in a low temperature environment, the primary side relief valve opens to release the hydraulic oil in the oil supply passage, so that the high pressure operation supplied from the oil pump The oil flows into the pressure chamber after reducing the pressure in the oil supply passage. For this reason, an increase in pressure in the pressure chamber is prevented, and the chain is unlikely to be over-tensioned.

  Further, a secondary side relief passage connected to the pressure chamber is further provided, and the secondary side relief valve is opened in the secondary side relief passage when the pressure in the pressure chamber becomes larger than a preset pressure. When the chain is abruptly tensioned and the pressure in the pressure chamber increases, the secondary relief valve opens to release the hydraulic oil in the pressure chamber, and as a result, the plunger moves in the pushing direction. So the chain will not be over tensioned.

  In addition, when the check valve valve body uses a ceramic ball or a steel ball with a ceramic coating, the wear of the valve body due to the soot contained in the hydraulic oil when it is incorporated in a diesel engine. Therefore, the responsiveness of the check valve to pressure fluctuations in the pressure chamber can be ensured over a long period of time.

  In addition, when a diamond-like carbon film is formed on the contact surface of the valve body of the check valve, the wear of the contact surface of the valve body due to the suit contained in the hydraulic oil is suppressed when incorporated in a diesel engine. Therefore, the responsiveness of the check valve to the pressure fluctuation in the pressure chamber can be ensured over a long period of time.

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

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

  As shown in FIG. 2, the chain tensioner 1 has a bottomed cylindrical housing 9 with one end opened, and a plunger 10 slidably inserted in the housing 9 in the axial direction. The engine cover 11 is fitted into the tensioner mounting hole 12 with the open end facing the engine cover 11. A flange portion 13 is integrally formed on the outer periphery of the housing 9, and the flange portion 13 is fixed to the outer surface of the engine cover 11 with bolts 14 (see FIGS. 1 and 3). A gasket 15 is sandwiched between the flange portion 13 and the engine cover 11 in order to prevent leakage of hydraulic oil from the chain tensioner 1.

  The plunger 10 is formed in a bottomed cylindrical shape whose opening end into the housing 9 is opened, and a female screw 16 is formed on the inner periphery thereof. Further, a screw rod 18 having a male screw 17 that engages with the female screw 16 on the outer periphery is inserted into the plunger 10. The screw rod 18 is supported at a protruding end from the plunger 10 by a rod sheet 19 provided at the bottom of the housing 9.

  The male screw 17 and the female screw 16 are formed in a sawtooth shape in which the flank angle of the pressure side flank 20 that receives pressure when a force in the direction of pushing the plunger 10 into the housing 9 is larger than the flank angle of the play side flank 21. ing. For example, the flank angle of the pressure flank 20 can be 65 °, the flank angle of the play flank 21 can be 7 °, and the flank angle of the pressure flank 20 can be 75 °. The flank angle of the side flank 21 can be 15 °.

  The surface of the screw rod 18 is shot peened, and the surface of the male screw 17 is textured. Here, the surface roughness of the matte surface of the pressure side flank 20 is preferably set to Ra 1.6 to 12.5, and more preferably set to Ra 3.2 to 6.3. Here, the satin surface of Ra 1.6 to 12.5 can be formed by shot peening using, for example, a grid of # 46 (167 μm to 652 μm, JIS G5903), and a satin surface of Ra 3.2 to 6.3. Can be formed by, for example, shot peening using a 273 μm grid as a medium. When heat treatment (for example, carburizing treatment or nitriding treatment) is performed on the screw rod 18, the shot peening is performed before the heat treatment.

  Further, a non-reactive layer is formed on the surface of the male screw 17 to prevent the formation of a lubricating film by the oil additive. Examples of such a non-reactive layer include a non-ferrous metal film (diamond-like carbon (DLC) film, ceramic film, carbon film, etc.), and a nitride compound layer formed by subjecting the screw rod 18 to soft nitriding. Is mentioned.

  The plunger 10 is urged in a direction protruding from the housing 9 by a return spring 22 incorporated between the plunger 10 and the screw rod 18, and a protruding end from the housing 9 is in contact with the chain guide 8. The plunger 10 is also urged in the direction of protruding from the housing 9 by an assist spring 23 incorporated between the plunger 10 and the rod seat 19.

  As shown in FIG. 4, an oil supply passage 25 for introducing hydraulic oil from the outside is connected to the pressure chamber 24 surrounded by the housing 9 and the plunger 10. The oil supply passage 25 has an inlet opening at a mating surface of the flange portion 13 with respect to the engine cover 11, and hydraulic oil supplied from an oil pump (not shown) through an oil hole 26 formed in the engine cover 11. The pressure chamber 24 is introduced.

  A check valve 27 is provided at the outlet of the oil supply passage 25 to prevent the backflow of hydraulic oil from the pressure chamber 24 to the oil supply passage 25. The check valve 27 includes a spherical valve body 29 that opens and closes a valve hole 28 formed in the rod seat 19, and a retainer 30 that regulates the movement range of the valve body 29.

Here, the valve body 29 of the check valve 27 is preferably a ceramic ball or a steel ball with a ceramic coating. In this way, when the chain tensioner 1 is incorporated in a diesel engine, the wear of the valve body 29 due to the soot contained in the hydraulic oil can be suppressed, and the response of the check valve 27 to the pressure fluctuation in the pressure chamber 24 Sex can be secured over a long period of time. Examples of the type of ceramic include alumina (AI ₂ O ₃ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N ₄ ), and silicon carbide (SiC).

  The rod sheet 19 is preferably formed with a diamond-like carbon (DLC) film on the contact surface of the valve body 29. In this way, when the chain tensioner 1 is incorporated in a diesel engine, the wear of the contact surface of the valve body 29 due to the suit contained in the hydraulic oil can be suppressed, and the check valve 27 against the pressure fluctuation in the pressure chamber 24 can be suppressed. Responsiveness can be ensured over a long period of time.

  From the middle of the oil supply passage 25, a primary side escape passage 31 for releasing the hydraulic oil in the oil supply passage 25 is branched. The primary side escape passage 31 includes a radial hole 32 extending from the outer periphery of the flange portion 13 to the oil supply passage 25 and an axial hole 33 extending from the mating surface of the flange portion 13 to the engine cover 11 to the radial hole 32. An outlet is opened in the mating surface of the portion 13 with respect to the engine cover 11. A primary-side relief valve 34 is inserted into the radial hole 32 from the outer periphery of the flange portion 13 and fixed with a set screw 35. As shown in FIG. 6, the set screw 35 has a screw surface coated with a sealant, and prevents hydraulic oil in the radial hole 32 from flowing out from the outer periphery of the flange portion 13.

  As shown in FIG. 5, the primary side relief valve 34 includes a valve sleeve 36, a spherical valve body 37 accommodated in the valve sleeve 36, and a valve seat in which the valve body 37 is formed at one end of the valve sleeve 36. A valve spring 39 that is biased toward the valve 38 and a cap 40 that is press-fitted into the other end of the valve sleeve 36. The valve seat 38 is formed with a valve hole 41 that communicates with the radial hole 32. An oil passage hole 42 communicating with the axial hole 33 is formed on the side surface of the sleeve 36. Therefore, when the pressure in the radial hole 32 becomes larger than the urging force of the valve spring 39, the valve spring 39 is compressed and the valve body 37 is separated from the valve seat 38, and the radial hole 32 moves from the axial hole 33 to the axial hole 33. Oil flows. As the valve body 37, for example, a steel ball can be used.

  As shown in FIG. 2, an oil passage groove 43 extending from the outlet of the primary side escape passage 31 to the outer periphery of the housing 9 is formed on the mating surface of the flange portion 13 with respect to the engine cover 11. Further, a flat surface 44 is formed on the outer periphery of the housing 9, and the oil passage groove 43 is formed in the engine cover 11 through a gap formed between the flat surface 44 and the inner periphery of the tensioner mounting hole 12. It communicates with the engine room.

  Connected to the pressure chamber 24 is a secondary side escape passage 45 through which hydraulic oil in the pressure chamber 24 is released. The secondary side escape passage 45 includes a radial hole 47 extending from the outer periphery of the flange portion 13 to the pressure chamber 24, and an axial hole 48 extending from the mating surface of the flange portion 13 to the engine cover 11 to the radial hole 47. An outlet is opened on the mating surface of the flange portion 13 with respect to the engine cover 11. The secondary relief passage 45 incorporates a secondary relief valve 46 that opens when the pressure in the pressure chamber 24 becomes higher than a preset pressure.

  An oil passage groove 49 extending from the outlet of the secondary escape passage 45 to the outer periphery of the housing 9 is formed on the mating surface of the flange portion 13 with respect to the engine cover 11. Further, a flat surface 50 is formed on the outer periphery of the housing 9, and an oil passage groove 49 is formed in the engine cover 11 through a gap formed between the flat surface 50 and the inner periphery of the tensioner mounting hole 12. Communicating with

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

  When the tension of the chain 6 is reduced during the operation of the engine, the plunger 10 moves in the protruding direction by the urging force of the return spring 22 and the assist spring 23 and absorbs the slack of the chain 6. At this time, since the hydraulic oil supplied from the oil pump flows into the pressure chamber 24 through the oil supply passage 25, the plunger 10 moves quickly.

  On the other hand, when the tension of the chain 6 increases during engine operation, the plunger 10 moves in the pushing direction by the tension of the chain 6 and absorbs the tension of the chain 6. At this time, the screw rod 18 rotates with respect to the plunger 10 while repeating forward and backward movements within the gap between the female screw 16 and the male screw 17 due to the vibration of the chain 6. Moreover, since the hydraulic oil in the pressure chamber 24 flows out into the engine room through the leak gap 51 between the sliding surface of the plunger 10 and the housing 9 and a damper action occurs, the plunger 10 moves slowly.

  When the engine is stopped, the tension of the chain 6 may increase depending on the stop position of a cam (not shown) connected to the camshaft 4. In this case, the chain 6 does not vibrate, so the pressure side of the internal thread 16 of the plunger 10 The flank 20 is received by the pressure side flank 20 of the male screw 17 of the screw rod 18, and the position of the plunger 10 is fixed. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  When the chain 6 is abruptly tensioned during engine operation, the pressure in the pressure chamber 24 increases with the check valve 27 closed, and the secondary relief valve 46 is opened. As a result, the hydraulic oil in the pressure chamber 24 escapes to the engine room through the secondary side escape passage 45, so that the plunger 10 moves in the pushing direction and the tension of the chain 6 is absorbed.

  Further, when high-pressure hydraulic oil is supplied from the oil pump through the oil hole 26 in a cold region or a low temperature environment in winter, the pressure in the oil supply passage 25 increases and the primary relief valve 34 opens. As a result, the hydraulic oil in the oil supply passage 25 escapes to the engine room, and the pressure increase in the oil supply passage 25 is suppressed.

  In this way, the chain tensioner 1 opens the primary side relief valve 34 when the pressure in the oil supply passage 25 becomes high under a low temperature environment, and releases the hydraulic oil in the oil supply passage 25. The supplied high-pressure hydraulic oil flows into the pressure chamber 24 after the pressure is reduced in the oil supply passage 25. For this reason, an increase in pressure in the pressure chamber 24 is prevented, and the chain 6 is unlikely to be over-tensioned.

  Further, in this chain tensioner 1, since the pressure side flank 20 of the male screw 17 is satin, it is difficult for the male screw 17 and the female screw 16 to slide between the pressure side flank 20, 20 when the engine is stopped, and the position of the plunger 10 is securely fixed. can do.

Further, since this chain tensioner 1 is provided with a non-reactive layer on the surface of the male screw 17, oil (so-called FM oil) to which molybdenum dithiocarbamate (MoDTC) or molybdenum dithiophosphate (MoDTP) is added is used as hydraulic oil. In this case, a lubricating film containing molybdenum disulfide (MoS ₂ ) is hardly formed on the surface of the male screw 17, and it is possible to reliably prevent slippage between the pressure side flank 20, 20 of the male screw 17 and the female screw 16. Can do.

  FIG. 7 shows a chain tensioner 61 according to a second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  A housing groove 63 for housing the register ring 62 is formed on the inner periphery of the open end of the housing 9, and the register ring 62 housed in the housing groove 63 elastically tightens the outer periphery of the plunger 10. A plurality of circumferential grooves 64 are formed on the outer periphery of the plunger 10 at regular intervals in the axial direction, and the register ring 62 is engaged with the circumferential grooves 64.

  In each circumferential groove 64, when the plunger 10 is pressed in a direction protruding from the housing 9, the diameter of the register ring 62 is increased to allow the plunger 10 to move, and the plunger 10 is placed in the housing 9. Is provided with a stopper surface 66 that locks the register ring 62 and prevents the plunger 10 from moving when the chain 6 is pushed in the direction in which the chain 6 is pushed. The engagement of the groove 64 and the register ring 62 restricts the movement of the plunger 10 in the pushing direction.

  A check valve 67 is provided at the outlet of the oil supply passage 25 to prevent the backflow of hydraulic oil from the pressure chamber 24 to the oil supply passage 25. The check valve 67 includes a valve seat 68 provided at the bottom of the housing 9, a spherical valve body 70 that opens and closes a valve hole 69 formed in the valve seat 68, and a retainer 71 that regulates the movement range of the valve body 70. Consists of. As in the first embodiment, when the valve body 70 employs a ceramic ball or a steel ball with a ceramic coating, when the chain tensioner 61 is incorporated in a diesel engine, the valve is a suit (soot) contained in hydraulic oil. Wear of the body 70 can be suppressed. Further, when the valve seat 68 is formed with a diamond-like carbon (DLC) film on the contact surface of the valve body 70, when the chain tensioner 61 is incorporated in a diesel engine, the valve body 70 by the suit contained in the hydraulic oil is used. Wear of the contact surface can be suppressed.

  As in the first embodiment, the chain tensioner 61 opens the primary side relief valve 34 to release the hydraulic oil in the oil supply passage 25 when the pressure in the oil supply passage 25 becomes high under a low temperature environment. The high-pressure hydraulic oil supplied from the oil pump flows into the pressure chamber 24 after reducing the pressure in the oil supply passage 25. For this reason, an increase in pressure in the pressure chamber 24 is prevented, and the chain 6 is unlikely to be over-tensioned.

The front view which shows the chain transmission apparatus incorporating the chain tensioner of 1st Embodiment of this invention 1 is an enlarged cross-sectional view near the chain tensioner of FIG. Sectional view along line III-III in FIG. Sectional view along line IV-IV in FIG. Fig. 4 is an enlarged cross-sectional view near the primary relief valve. FIG. 5 is an enlarged sectional view of the vicinity of the screw surface of the set screw. The expanded sectional view which shows the chain tensioner of 2nd Embodiment of this invention

Explanation of symbols

1 Chain tensioner 6 Chain 9 Housing 10 Plunger 11 Engine cover 12 Tensioner mounting hole 13 Flange 16 Female thread 17 Male thread 18 Screw rod 20 Pressure side flank 21 Play side flank 22 Return spring 24 Pressure chamber 25 Oil supply passage 27 Check valve 28 Valve hole 29 Valve body 31 Primary side relief passage 32 Radial hole 33 Axial hole 34 Primary side relief valve 35 Set screw 43 Oil groove 44 Flat surface 45 Secondary side relief passage 46 Secondary side relief valve 61 Chain tensioner 62 Register ring 63 Groove 64 Circumferential groove 65 Tapered surface 66 Stopper surface 69 Valve hole 70 Valve body

Claims (7)

A plunger (10) is slidably inserted into a bottomed cylindrical housing (9) whose one end is open, and the plunger (10) has a bottomed cylindrical shape whose opening end into the housing (9) is open. An oil supply passage (25) for introducing hydraulic oil is provided in a pressure chamber (24) surrounded by the housing (9) and the plunger (10), and the pressure chamber (24) is provided at the outlet of the oil supply passage (25). ) Is provided with a check valve (27) for preventing backflow of hydraulic oil from the oil supply passage (25), and a return spring (22) for urging the plunger (10) in a direction protruding from the housing (9) is provided. so as to press the chain (6) end protruding from the housing (9) of the plunger (10), tensioner state fitted into the mounting hole (12) of the housing (9) of the engine cover (11) In the chain tensioner provided flange portion fixed to the outer surface of the engine cover (11) and (13) on the outer periphery of the housing (9),
A primary side escape passage (31) branched from the middle of the oil supply passage (25) positioned outside the outer surface of the engine cover (11) is provided, and the oil supply passage (25) is provided in the primary side escape passage (31). ) see write set the primary relief valve to open (34) when the pressure is greater than the preset pressure in the primary side to the mating surface for the engine cover (11) of said flange portion (13) An outlet of the escape passage (31) is opened, and an oil passage groove (43) extending from the outlet of the primary side escape passage (31) to the outer periphery of the housing (9) is provided in the engine cover (11) of the flange portion (13). Formed on the mating surface of the housing (9) and through the gap formed between the flat surface (44) provided on the outer periphery of the housing (9) and the inner periphery of the tensioner mounting hole (12). Chain tensioner, characterized in that the groove (43) made to communicate in the engine cover (11).   A secondary-side escape passage (45) connected to the pressure chamber (24) is further provided, and the pressure in the pressure chamber (24) is larger than a preset pressure in the secondary-side escape passage (45). 2. The chain tensioner according to claim 1, further comprising a secondary relief valve (46) that opens when the secondary tension valve is opened. A screw rod (18) having a male screw (17) threadedly engaged with a female screw (16) formed on the inner periphery of the plunger (10) is provided on the outer periphery, and the male screw (17) and the female screw (16) 10) The flank angle of the pressure side flank (20) that receives pressure when a force in the direction of pushing the housing into the housing (9) is applied is formed in a sawtooth shape larger than the flank angle of the play side flank (21). The chain tensioner according to claim 1 or 2.   A register ring (62) that elastically tightens the outer periphery of the plunger (10) is accommodated in an accommodation groove (63) formed in the inner periphery of the housing (9), and the register ring (62) is accommodated in the plunger (10). ) Is engaged with a circumferential groove (64) formed at regular intervals in the axial direction, and the plunger (10) is moved from the housing (9) into each circumferential groove (64). When pressed in the protruding direction, the diameter of the register ring (62) is increased to allow the plunger (10) to move, and the plunger (10) is pushed into the housing (9). The chain tensioner according to claim 1 or 2, further comprising a stopper surface (66) for locking the register ring (62) to prevent movement of the plunger (10) when pressed. The primary side relief passage (31) has a radial hole (32) extending from the outer periphery of the flange portion (13) to the oil supply passage (25), and a mating surface of the flange portion (13) with respect to the engine cover (11) The primary relief valve (34) is inserted into the radial hole (32) from the outer periphery of the flange portion (13) and stopped. The chain tensioner according to any one of claims 1 to 4, wherein the chain tensioner is fixed with a screw (35). The check valve (27) has a spherical valve body (29) for opening and closing a valve hole (28), and the valve body (29) is a ceramic ball or a steel ball coated with a ceramic coating. To 5. The chain tensioner according to any one of 5 to 5 . The chain tensioner according to any one of claims 1 to 6 , wherein a diamond-like carbon film is formed on a contact surface of the valve body (29) of the check valve (27).

Images