JP2010144903A - Chain tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chain tensioner capable of securing air exhaust performance from a pressure chamber for a long term. <P>SOLUTION: The chain tensioner 1 is structured such that a plunger 10 is slidably inserted into a cylinder 9, an oil supply passage 13 for introducing a hydraulic oil is installed in a pressure chamber 12 surrounded by the plunger 10 and cylinder 9, a check valve 14 for preventing a backflow of the hydraulic oil is installed an outlet of the oil supply passage 13, a through-hole 22 for communicating between the pressure chamber 12 and outside air is formed in the cylinder 9, a male screw member 24 with a head part 24a is screwed into a female screw 23 formed in an inner periphery of the through-hole 22 and air trapped in the pressure chamber 12 is discharged to outside air through the medium of a spiral screw clearance formed between the male screw member 24 and female screw 23. A toothed washer 25 is assembled between the head part 24a of the male screw member 24 and cylinder 9, and a plurality of exhaust ports 27 are formed between the head part 24a of the male screw member 24 and cylinder 9 by the teeth 26 of the toothed washer 25. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 return spring is inserted into a bottomed cylindrical cylinder with one end opened so as to be slidable in the axial direction, and the plunger is urged in a direction protruding from the cylinder. It is known that an oil supply passage for introducing hydraulic oil is provided in a pressure chamber surrounded by the plunger and the cylinder, and a check valve for preventing backflow of the hydraulic oil is provided at the outlet of the oil supply passage (patent) Reference 1).

  When the chain tension increases during engine operation, the chain tensioner moves in the direction in which the plunger is pushed into the cylinder (hereinafter referred to as “push-in direction”) due to the chain tension, and absorbs 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 cylinder, and a damper action is generated by the viscous resistance of the hydraulic oil, so that the plunger moves slowly.

  On the other hand, when the tension of the chain is reduced during engine operation, the plunger moves in a direction protruding from the cylinder (hereinafter referred to as “protruding direction”) by the urging force of the return spring, and absorbs the slackness of the chain. At this time, the check valve is opened and hydraulic oil flows into the pressure chamber from the oil supply passage, so that the plunger moves quickly.

  In such a chain tensioner, if air enters the hydraulic oil supplied from the oil supply passage to the pressure chamber, or if air precipitates due to pressure fluctuations in the pressure chamber, when the chain tension increases, the pressure chamber Since the plunger moves when the air is compressed, the damper action of the chain tensioner is reduced.

  In order to prevent the reduction of the damper action, in the chain tensioner described in Patent Document 1, a through hole that communicates the pressure chamber and the outside air is formed in the cylinder, and the head is attached to the female screw formed on the inner periphery of the through hole. An attached male screw member is screwed in, and air mixed in the pressure chamber is discharged to the outside through a helical screw gap formed between the male screw member and the female screw.

Here, the male screw member is a single thread which is generally commercially available, and has a full screw shape in which the screw portion and the head are directly connected. In order to prevent loosening of the male screw member, a spring washer is incorporated between the head of the male screw member and the cylinder. Here, the spring washer has a shape in which a part of the circumference is cut off, and air is discharged through a gap in a part in which the part of the circumference is cut off.
JP 2007-321899 A

  However, since the gap between the spring washer's circumference is very small, clogging is likely to occur. In particular, in a diesel engine, foreign matter such as soot and contamination is often mixed in the hydraulic oil supplied from the oil supply passage to the pressure chamber, so the gap in the part where the circumference of the spring washer is cut off. It was easy to clog.

  If foreign matter is clogged in the gap between the part where the spring washer's circumference is cut off, the air mixed in the pressure chamber will be difficult to be discharged, so the damper action of the chain tensioner will decrease and the chain amplitude will increase. Otherwise, the sliding surface of the plunger may be worn abnormally or abnormal noise may occur in the engine.

  The problem to be solved by the present invention is to provide a chain tensioner that can ensure the performance of discharging air from the pressure chamber over a long period of time.

  In order to solve the above problems, a toothed washer having a plurality of radially extending twisted teeth spaced in the circumferential direction is incorporated between the head of the male screw member and the cylinder, and the teeth of the toothed washer Thus, a plurality of exhaust ports are formed between the head of the male screw member and the cylinder.

  In this way, even when any one of the plurality of exhaust ports formed between the head of the male screw member and the cylinder is clogged, Air can be discharged. Therefore, stable air discharge is possible over a long period of time.

  Examples of the toothed washer include an external tooth shape having teeth extending radially outward, an internal tooth shape having teeth extending radially inward, and a tooth extending radially outward and radially inward. An internal and external tooth shape having teeth extending in the direction can be employed. Further, when the toothed washer is formed of chromium molybdenum steel, the durability of the toothed washer can be ensured.

  The screw of the male screw member is preferably a multi-threaded screw. In this way, since a multi-threaded screw gap is formed between the male screw member and the female screw, even if any one of the screw gaps is clogged, the pressure is passed through the other screw gaps. Indoor air can be discharged. Therefore, stable air discharge is possible over a long period of time.

  The male screw member may be a full screw type, and a part of the screw portion may be screw-engaged with the female screw, but the screw portion of the male screw member is interposed through a small-diameter shaft portion having a smaller diameter than the root diameter of the screw. It is preferable that the screw is connected to the head and the entire length of the screw portion is screw-engaged with the female screw. In this way, even when there is a variation in the tightening torque of the male screw member, the engagement length between the screw portion and the female screw is constant, and the length of the screw gap does not vary, so the air discharge performance is stable. .

  When a small-diameter shaft portion is provided on the male screw member, an annular space is formed between the chamfered portion and the small-diameter shaft portion when a chamfered portion is provided at the opening edge on the outside air side of the through hole. The flow resistance in the air is reduced, and the air discharge performance is further stabilized.

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

  Since the chain tensioner of the present invention exhausts the air in the pressure chamber through a plurality of exhaust ports formed between the head of the male screw member and the cylinder, even when any of the exhaust ports is clogged, The air in the pressure chamber can be discharged through another exhaust port. Therefore, stable air discharge is possible 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 an engine crankshaft 2 and a sprocket 5 fixed to a camshaft 4 are connected via a chain 6, and the chain 6 rotates the crankshaft 2. This is transmitted to the camshaft 4, and the valve (not shown) of the combustion chamber is opened and closed by the rotation of the camshaft 4.

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

  The chain tensioner 1 has a bottomed cylindrical cylinder 9 with one end opened, and a plunger 10 inserted into the cylinder 9 so as to be slidable in the axial direction. The cylinder 9 is fixed to an engine block (not shown) with bolts 11.

  As shown in FIG. 2, an oil supply passage 13 that communicates with a pressure chamber 12 surrounded by the cylinder 9 and the plunger 10 is formed in the cylinder 9. The oil supply passage 13 is connected to an oil supply pump (not shown), and hydraulic oil sent from the oil supply pump is introduced into the pressure chamber 12. A check valve 14 is provided at the outlet of the oil supply passage 13 to prevent backflow of hydraulic oil.

  A leak gap 15 is formed between the sliding surfaces of the plunger 10 and the cylinder 9, and hydraulic oil in the pressure chamber 12 flows out through the leak gap 15.

  The plunger 10 is urged in a direction protruding from the cylinder 9 by a return spring 16 incorporated in the pressure chamber 12. One end of the return spring 16 is supported by the check valve 14, and the other end presses the plunger 10.

  An annular housing groove 17 is formed on the inner periphery of the cylinder 9, and a register ring 18 is housed in the housing groove 17 so as to be movable in the axial direction. The register ring 18 has a ring shape that lacks a part of the circumference, and is elastically deformable in the radial direction. The register ring 18 elastically tightens the outer periphery of the plunger 10, and engages with one of a plurality of circumferential grooves 19 formed on the outer periphery of the plunger 10 at regular intervals in the axial direction. .

  Within each circumferential groove 19, when a load in the protruding direction is applied to the plunger 10, a taper surface 20 that allows the movement of the plunger 10 by expanding the diameter of the register ring 18, and a load in the pushing direction of the plunger 10. Is provided with a stopper surface 21 that locks the register ring 18 and restricts the movement of the plunger 10 when a load is applied.

  The cylinder 9 is formed with a through hole 22 that communicates the pressure chamber 12 and the outside air.

  As shown in FIG. 3, a female screw 23 is formed on the inner periphery of the through hole 22, and a male screw member 24 with a head 24 a is screwed into the female screw 23. Here, the male screw member 24 has a screw portion 24b connected to the head portion 24a via a small-diameter shaft portion 24c having a diameter smaller than the root diameter of the screw, and the entire length of the screw portion 24b is screw-engaged with the female screw 23. is doing. Further, the screw of the male screw member 24 is a multi-threaded screw, and a spiral screw gap is formed between the male screw member 24 and the female screw 23 in multiple threads.

  A toothed washer 25 is incorporated between the head 24 a of the male screw member 24 and the cylinder 9. As shown in FIG. 4, the toothed washer 25 has a plurality of twisted teeth 26 extending radially outwardly at intervals in the circumferential direction, and by means of the teeth 26, as shown in FIG. A plurality of exhaust ports 27 are formed between 24 a and the cylinder 9. The toothed washer 25 is made of chromium molybdenum steel (so-called SCM steel) in order to ensure its durability.

  A chamfered portion 28 is provided at the opening edge of the through hole 22 on the outside air side, and an annular space is formed between the chamfered portion 28 and the small diameter shaft portion 24c.

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

  When the tension of the chain 6 increases during the operation of the engine, 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, since the damper force is generated by the viscous resistance of the hydraulic oil flowing out from the pressure chamber 12 through the leak gap 15, the plunger 10 moves slowly.

  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 16 and absorbs the slack of the chain 6. At this time, the check valve 14 is opened, and the hydraulic oil flows into the pressure chamber 12 from the oil supply passage 13, so that the plunger 10 moves quickly.

  Here, when the plunger 10 repeats advancing and retreating due to the vibration of the chain 6, the register ring 18 moves back and forth within the accommodation groove 17. Further, when the movement range in the protruding direction of the plunger 10 exceeds the movable range in the receiving groove 17 of the register ring 18 due to the slack of the chain 6, the tapered surface 20 in the circumferential groove 19 is changed to the register ring 18. Is expanded to allow the plunger 10 to move. At this time, the register ring 18 engages with the adjacent circumferential groove 19.

  When the engine is stopped, the tension of the chain 6 may increase depending on the stop position of the camshaft 4. In this case, the engagement of the register ring 18 and the circumferential groove 19 prevents the plunger 10 from moving in the pushing direction. The Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  When starting the engine, air may be mixed into the hydraulic oil supplied to the pressure chamber 12 through the oil supply passage 13, or air may precipitate due to pressure fluctuations in the pressure chamber 12 during engine operation. In this case, the air in the pressure chamber 12 includes a screw gap between the male screw member 24 and the female screw 23, an annular space between the chamfered portion 28 and the small diameter shaft portion 24c, and an exhaust port between the head portion 24a and the cylinder 9. 27 to the outside air in order.

  The chain tensioner 1 is configured such that even when any one of the plurality of exhaust ports 27 formed between the head portion 24a of the male screw member 24 and the cylinder 9 is clogged, the other exhaust ports 27 are arranged. Through this, the air in the pressure chamber 12 is discharged. Therefore, stable air discharge is possible over a long period of time.

  In addition, since the thread tension between the male thread member 24 and the female thread 23 is multiple in the chain tensioner 1, even if any one of the thread gaps is clogged, the pressure is passed through the other thread gaps. The air in the chamber 12 is discharged. Therefore, stable air discharge is possible over a long period of time.

  Further, in this chain tensioner 1, since the entire length of the threaded portion 24b of the male screw member 24 is screw-engaged with the female screw 23, even when the tightening torque of the male screw member 24 varies, the threaded portion 24b and the female screw 23 The engagement length is constant, and the length of the screw gap does not vary. Therefore, the air discharging performance is more stable than the case where the male screw member 24 is a full screw type and a part of the screw portion is screw-engaged with the female screw 23.

  Further, in this chain tensioner 1, since the annular space is formed between the chamfered portion 28 and the small diameter shaft portion 24c, the flow resistance on the outside air side is smaller than the screw gap, and the chamfered portion 28 is not provided. Compared with, air discharge performance is stable.

  In the above embodiment, the toothed washer 25 incorporated between the head portion 24a of the male screw member 24 and the cylinder 9 has been described as an example of an external tooth shape having teeth 26 extending radially outward. As shown in FIG. 5, an internal toothed washer 30 having teeth 29 extending radially inward may be used. Even in this case, a plurality of exhaust ports can be formed between the head 24 a of the male screw member 24 and the cylinder 9 by the teeth 29 of the toothed washer 30 as in the above embodiment. Further, as shown in FIG. 6, an internally and externally toothed washer 31 having teeth 26 extending radially outward and teeth 29 extending radially inward may be used.

  FIG. 7 shows a chain tensioner 41 according to the second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The plunger 10 is formed in a bottomed cylindrical shape whose opening end into the cylinder 9 is opened, and a female screw 42 is formed on the inner periphery thereof. A screw rod 44 having a male screw 43 that engages with the female screw 42 on the outer periphery is incorporated in the plunger 10. One end of the screw rod 44 protrudes from the plunger 10, and the protruding end is in contact with a rod sheet 45 provided in the cylinder.

  The male screw 43 and the female screw 42 are formed in a sawtooth shape in which the flank angle of the pressure side flank 46 that receives pressure when a load in the direction of pushing the plunger 10 into the cylinder 9 is applied is larger than the flank angle of the play side flank 47. Has been.

  A return spring 16 is incorporated in the pressure chamber 12 surrounded by the cylinder 9 and the plunger 10. One end of the return spring 16 is supported by the screw rod 44 and the other end presses the plunger 10 via the spring seat 48, and the pressurization biases the plunger 10 in a direction to protrude from the cylinder 9. .

  An example of the operation of the chain tensioner 41 will be described.

  When the tension of the chain 6 increases during the operation of the engine, 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 44 rotates with respect to the plunger 10 while repeating the forward and backward movements within the range of the axial gap between the female screw 42 and the male screw 43 due to the vibration of the chain 6. Further, since the damper force is generated by the viscous resistance of the hydraulic oil flowing out from the pressure chamber 12 through the leak gap 15, the plunger 10 moves slowly.

  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 16 and absorbs the slack of the chain 6. At this time, since the hydraulic oil flows from the oil supply passage 13 into the pressure chamber 12, the plunger 10 moves quickly.

  When the engine is stopped, the tension of the chain 6 may increase depending on the stop position of the camshaft 4. In this case, since the chain 6 does not vibrate, the internal thread 42 of the plunger 10 is received by the external thread 43 of the screw rod 44. 10 is prevented from moving in the pushing direction. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  When starting the engine, air may be mixed into the hydraulic oil supplied to the pressure chamber 12 through the oil supply passage 13, or air may precipitate due to pressure fluctuations in the pressure chamber 12 during engine operation. In this case, the air in the pressure chamber 12 is discharged to the outside air through the screw gap between the male screw member 24 and the female screw 23 and the exhaust port 27 between the head 24 a and the cylinder 9.

  This chain tensioner 41 is provided with another exhaust port 27 even when one of the plurality of exhaust ports 27 formed between the head portion 24a of the male screw member 24 and the cylinder 9 is clogged. Through this, the air in the pressure chamber 12 is discharged. Therefore, stable air discharge is possible over a long period of time. Other effects are the same as those of the first embodiment.

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. FIG. 2 is an enlarged sectional view of the vicinity of the male screw member Enlarged perspective view of the toothed washer shown in FIG. The expansion perspective view which shows the modification of a toothed washer shown in FIG. The expanded perspective view which shows the other modification of the toothed washer shown in FIG. The expanded sectional view which shows the chain tensioner of 2nd Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chain tensioner 9 Cylinder 10 Plunger 12 Pressure chamber 13 Oil supply path 14 Check valve 16 Return spring 17 Housing groove 18 Register ring 19 Circumferential groove 20 Tapered surface 21 Stopper surface 22 Through hole 23 Female screw 24 Male screw member 24a Head portion 24b Screw portion 24c Small diameter shaft portion 25 Toothed washer 26 Tooth 27 Exhaust port 28 Chamfered portion 29 Tooth 30, 31 Toothed washer 41 Chain tensioner 42 Female thread 43 Male thread 44 Screw rod 45 Rod seat 46 Pressure side flank 47 Play side flank

Claims (10)

A return spring that slidably inserts a plunger (10) in a cylindrical cylinder (9) with an open end in an axial direction and urges the plunger (10) to protrude from the cylinder (9). (16) is provided, an oil supply passage (13) for introducing hydraulic oil is provided in a pressure chamber (12) surrounded by the plunger (10) and the cylinder (9), and an outlet of the oil supply passage (13) is provided. A check valve (14) for preventing backflow of hydraulic oil is provided, and a through hole (22) for communicating the pressure chamber (12) and outside air is formed in the cylinder (9). A male screw member (24) having a head (24a) is screwed into a female screw (23) formed on the periphery, and air mixed in the pressure chamber (12) is supplied to the male screw member (24) and the female screw (23). Helical screw gap formed between In the chain tensioner which is adapted to discharge to the outside air through,
A toothed washer (25) having a plurality of radially extending twisted teeth (26) spaced circumferentially is interposed between the head (24a) of the male screw member (24) and the cylinder (9). And a plurality of exhaust ports (27) are formed between the head (24a) of the male screw member (24) and the cylinder (9) by the teeth (26) of the toothed washer (25). A chain tensioner characterized by   The chain tensioner according to claim 1, wherein the toothed washer is an externally toothed washer (25) having teeth (26) extending radially outward.   The chain tensioner according to claim 1, wherein the toothed washer is an internally toothed toothed washer (30) having teeth (29) extending radially inward.   The chain tensioner according to claim 1, wherein the toothed washer is an internally and externally toothed washer (31) having teeth (26) extending radially outward and teeth (29) extending radially inward.   The chain tensioner according to any one of claims 1 to 4, wherein the toothed washer (25) is made of chromium molybdenum steel.   The chain tensioner according to any one of claims 1 to 5, wherein a screw of the male screw member (24) is a multi-threaded screw.   The screw portion (24b) of the male screw member (24) is connected to the head portion (24a) via a small-diameter shaft portion (24c) having a diameter smaller than the root diameter of the screw, and the entire length of the screw portion (24b). The chain tensioner according to any one of claims 1 to 6, wherein the thread tensioner engages with the female thread (23).   The chain tensioner according to claim 7, wherein a chamfered portion (28) is provided at an opening edge on the outside air side of the through hole (22).   A register ring (18) for elastically tightening the outer periphery of the plunger (10) is accommodated in an annular accommodating groove (17) formed in the inner periphery of the cylinder (9), and the register ring (18) is The plunger (10) is engaged with a circumferential groove (19) formed on the outer periphery of the plunger (10) at a constant interval in the axial direction, and the plunger (10) is placed in a cylinder ( 9) When a load in the direction of protruding from 9) is applied, the diameter of the register ring (18) is increased to allow the plunger (10) to move, and the plunger (10) is connected to the cylinder (9). A stopper surface (21) is provided for locking the register ring (18) and restricting the movement of the plunger (10) when a load in a direction to be pushed in is applied. Any Of the chain tensioner.   The plunger (10) is formed in a bottomed cylindrical shape whose opening end into the cylinder (9) is open, and a male screw (43) that engages with a female screw (42) formed on the inner periphery of the plunger (10). And a projecting end of the screw rod (44) from the plunger (10) is supported by a rod sheet (45) provided in the cylinder (9), and the male screw ( 43) and the female thread (42) are such that the flank angle of the pressure side flank (46) that receives pressure when a load in the direction of pushing the plunger (10) into the cylinder (9) is applied is the play side flank (47). The chain tensioner according to any one of claims 1 to 8, wherein the chain tensioner is formed in a sawtooth shape larger than the flank angle.

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