JP2010138942A - Chain tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chain tensioner which secures exhaust performance of air from a pressure chamber for a long term, and whose cost is low. <P>SOLUTION: In a chain tensioner 1 which has a plunger 10 inserted into a cylinder 9 so as to be slidable in an axial direction and which contains a return spring 18 biasing the plunger 10 in a projecting direction, an oil supply passage 21 introducing a hydraulic fluid into a pressure chamber 20 surrounded by the plunger 10 and cylinder 9 and a check valve 22 preventing hydraulic fluid backflow to an outlet of the oil supply passage 21, a through hole 24 communicating the pressure chamber 20 with the outside air is formed in the cylinder 9. A male screw member 26 made of a porous material is screwed in a female screw 25 formed in an inner periphery of the through hole 24 to simultaneously discharge air trapped in the pressure chamber 20 to the outside air through a spiral screw gap formed between the male screw member 26 and the female screw 25 and through continuous pores inside the male screw member 26. <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) References 1, 2).

  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 a male screw member is formed on the female screw formed on the inner periphery of the through hole. The 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.

Further, in the chain tensioner described in Patent Document 2, a through hole that communicates the pressure chamber and the outside air is formed in the cylinder, and a plug made of a porous material is press-fitted into the through hole. The air mixed in the pressure chamber is discharged to the outside air through the internal continuous pores.
JP 2007-321899 A JP 2002-364720 A

  By the way, since the screw gap between the male screw member and the female screw is one long and thin line, if the air in the pressure chamber is discharged through the screw gap as in Patent Document 1, the screw gap is likely to be clogged. In particular, in a diesel engine, foreign matters such as soot and contamination are often mixed in the hydraulic oil supplied from the oil supply passage to the pressure chamber, so that screw gaps are easily clogged.

  If the screw clearance is clogged, air mixed in the pressure chamber will not be discharged, and the damper action of the chain tensioner will decrease, increasing the amplitude of the chain, causing abnormal wear on the sliding surfaces of the cylinder and plunger, There is a risk of noise.

  Further, as in Patent Document 2, when a plug body made of a porous material is press-fitted into a through hole, it is necessary to manage the inner diameter dimension of the through hole and the outer diameter dimension of the plug body with high accuracy, and the processing cost is high. There was a problem.

  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 and that is low in cost.

  In order to solve the above-mentioned problem, a through-hole communicating with the pressure chamber and the outside air is formed in the cylinder, and a male screw member made of a porous material having continuous pores is screwed into a female screw formed on the inner periphery of the through-hole. The air mixed in the pressure chamber is discharged to the outside in parallel with the spiral screw gap formed between the male screw member and the female screw and the continuous pores inside the male screw member.

  In this way, since the continuous pores inside the male screw member are connected in a mesh shape, clogging is unlikely to occur, and air discharge performance can be ensured over a long period of time. Further, in parallel with the discharge of air through the continuous pores, the air is discharged through the screw gap between the male screw member and the female screw, so that the air discharge performance can be ensured for a longer period. Further, since the male screw member is attached by screwing rather than press-fitting, dimensional management with high accuracy is not required and the cost is low.

  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 amount of air released by combining the screw gap between the male screw member and the female screw and the continuous pores inside the male screw member is set to a range of 60 to 600 cc per 30 seconds under a 0.1 MPa load condition, for example. Can do.

  Further, the inventors of the present invention have found that even when the air bleeding amount is set in the range of 400 to 600 cc, the damper performance is hardly affected as compared with the case where the air bleeding amount is set to 60 cc. It was. When the air bleeding amount is set in the range of 400 to 600 cc, the air discharging performance can be ensured for a very long time.

  For example, a sintered metal or a sintered resin can be used as the porous material.

  When the male screw member has a head having a diameter larger than that of the through hole, it is preferable to incorporate a spring washer having a shape in which a part of the circumference is cut between the head and the cylinder. If it does in this way, loosening of a male screw member can be prevented. In addition, air passes through a portion where a part of the circumference of the spring washer is cut off.

  The nominal diameter of the male screw member can be set in the range of M3 to M8, for example.

The present invention can be applied to the following chain tensioner, for example.
1) 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.
2) A register ring that elastically tightens the outer periphery of the plunger is accommodated in an annular accommodating groove formed in the inner periphery of the cylinder, and the register ring is spaced apart from the outer periphery of the plunger at a certain interval in the axial direction. 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.

  Since the chain tensioner according to the present invention discharges air in parallel between the screw gap between the male screw member and the female screw and the continuous pores inside the male screw member, the air discharging performance can be ensured over a long period of time. Further, since the male screw member is attached by screwing rather than press-fitting, dimensional management with high accuracy is not required and the cost is low.

  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, the plunger 10 is formed in a bottomed cylindrical shape whose opening end into the cylinder 9 is opened, and a female screw 12 is formed on the inner periphery thereof. In the plunger 10, an iron screw rod 14 having a male screw 13 that engages with the female screw 12 on the outer periphery is incorporated. One end of the screw rod 14 protrudes from the plunger 10, and the protruding end is supported by a rod sheet 15 provided in the cylinder 9.

  The male screw 13 and the female screw 12 are formed in a sawtooth shape in which the flank angle of the pressure side flank 16 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 17. Has been.

  A return spring 18 is incorporated between the plunger 10 and the screw rod 14. One end of the return spring 18 is supported by the screw rod 14, and the other end presses the plunger 10 via the spring seat 19, and the pressing force urges the plunger 10 in a direction to protrude from the cylinder 9. .

  The cylinder 9 is formed with an oil supply passage 21 communicating with a pressure chamber 20 surrounded by the cylinder 9 and the plunger 10. The oil supply passage 21 is connected to an oil supply pump (not shown), and hydraulic oil fed from the oil supply pump is introduced into the pressure chamber 20. A check valve 22 is provided at the outlet of the oil supply passage 21 to prevent backflow of hydraulic oil.

  A leak gap 23 is formed between the sliding surfaces of the plunger 10 and the cylinder 9, and hydraulic oil in the pressure chamber 20 flows out through the leak gap 23.

  Further, the cylinder 9 is formed with a through hole 24 that communicates the pressure chamber 20 and the outside air, and a male screw member 26 is screwed into a female screw 25 formed on the inner periphery of the through hole 24. The male screw member 26 is made of a porous material (for example, sintered metal or sintered resin) having continuous pores, and allows air to pass through the continuous pores inside the male screw member 26.

  A helical screw gap is formed between the male screw member 26 and the female screw 25. Therefore, the air mixed in the pressure chamber 20 is discharged to the outside air in parallel between the screw gap between the male screw member 26 and the female screw 25 and the continuous pores inside the male screw member 26. Here, the screw of the male screw member 26 may be a single thread as shown in FIG. 3 (a). However, as shown in FIG. 3 (b), a multi-thread (two threads in the figure) is used. The screw gap is preferable because it has multiple threads.

  The male screw member 26 has a head 26 a having a larger diameter than the through hole 24. A spring washer 27 is incorporated between the head 26 a and the cylinder 9 in order to prevent the male screw member 26 from loosening. The spring washer 27 has a shape in which a part of the circumference is cut off, and air passes through a part in which the part of the circumference is cut off. The nominal diameter of the male screw member 26 is set in the range of M3 to M8.

  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 is moved in the protruding direction by the urging force of the return spring 18 to absorb the slack of the chain 6. At this time, since the hydraulic oil supplied from the oil pump flows into the pressure chamber 20 through the oil supply passage 21, 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 14 rotates with respect to the plunger 10 while repeating forward and backward movements within the range of the axial clearance between the female screw 12 and the male screw 13 due to the vibration of the chain 6. Further, since the hydraulic oil in the pressure chamber 20 flows out through the leak gap 23 between the sliding surfaces of the plunger 10 and the cylinder 9 and a damper action is generated by the viscous resistance of the hydraulic oil, the plunger 10 moves slowly. To do.

  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 that the internal thread 12 of the plunger 10 is screw screw rod. 14 is received by the male screw 13 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.

  There are cases where air is mixed into the hydraulic oil supplied to the pressure chamber 20 through the oil supply passage 21 or air is deposited due to pressure fluctuations in the pressure chamber 20 during engine operation. In this case, the pressure chamber The air in 20 passes through the screw gap between the male screw member 26 and the female screw 25 and the continuous pores inside the male screw member 26 and is quickly discharged to the outside air. Therefore, the damper action due to the air in the pressure chamber 20 is unlikely to decrease.

  In this chain tensioner 1, since the continuous pores inside the male screw member 26 are connected in a mesh shape, clogging is unlikely to occur and air discharge performance can be ensured over a long period of time. Further, in parallel with the discharge of air through the continuous pores, air is discharged through the screw gap between the male screw member 26 and the female screw 25, so that the air discharge performance can be ensured for a longer period. Further, since the male screw member 26 is attached by screwing rather than press-fitting, dimensional management with high accuracy is not required and the cost is low.

  The screw of the male screw member 26 is preferably a multi-threaded screw as shown in FIG. In this way, since a multi-threaded screw gap is formed between the male screw member 26 and the female screw 25, even if any one of the screw gaps is clogged, the other screw gaps are passed through. The air in the pressure chamber 20 can be discharged. Therefore, stable air discharge is possible over a long period of time.

  FIG. 4 shows a chain tensioner 31 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.

  An annular housing groove 32 is formed on the inner periphery of the cylinder 9, and a register ring 33 is housed in the housing groove 32 so as to be movable in the axial direction. The register ring 33 has a ring shape lacking a part of the circumference, and can be elastically deformed in the radial direction. The register ring 33 elastically tightens the outer periphery of the plunger 10 and engages with one of a plurality of circumferential grooves 34 formed on the outer periphery of the plunger 10 at a constant interval in the axial direction. .

  In each circumferential groove 34, when a load in the protruding direction is applied to the plunger 10, a taper surface 35 that allows the movement of the plunger 10 by expanding the diameter of the register ring 33, and a load in the pushing direction of the plunger 10. Is provided with a stopper surface 36 that locks the register ring 33 and restricts the movement of the plunger 10 when the chain 6 is loaded. When the tension of the chain 6 increases when the engine is stopped, the circumferential groove 34 is provided. The engagement of the register ring 33 restricts the movement of the plunger 10 in the pushing direction.

  The cylinder 9 has a through hole 24 that communicates the pressure chamber 20 with the outside air, and a male screw member 26 made of a porous material is screwed into a female screw 25 formed on the inner periphery of the through hole 24.

  As in the first embodiment, the chain tensioner 31 discharges air in parallel between the screw gap between the male screw member 26 and the female screw 25 and the continuous pores inside the male screw member 26. It can be secured for a long time. Further, since the male screw member 26 is attached by screwing rather than press-fitting, dimensional management with high accuracy is not required and the cost is low.

  In each of the above embodiments, the amount of air released by combining the screw gap between the male screw member 26 and the female screw 25 and the continuous pores inside the male screw member 26 is, for example, 60 to 30 per 30 seconds under a 0.1 MPa load condition. It can be set in the range of 600 cc. Here, if the air bleeding amount is set in the range of 400 to 600 cc, the air discharge performance can be secured for a very long time.

  Here, if the air bleeding amount is increased to 400 to 600 cc, the damper performance may be lowered. Therefore, a plurality of chain tensioner samples having different air bleeding amounts are prepared, and the plunger of each sample is set to a constant amplitude. The test which vibrates with was performed.

  Specifically, a plurality of samples with the air bleeding amount set to 60 cc, 400 cc, 500 cc, and 600 cc are prepared, and the plunger of each sample is vibrated with a shaker, which is generated by the damper action of the chain tensioner. The load to be measured was measured with a load cell attached to the shaker.

  As a result, as shown in FIG. 5, it is confirmed that even if the air bleeding amount is set in the range of 400 to 600 cc, the damper performance is hardly affected as compared with the case where the air bleeding amount is set to 60 cc. I was able to.

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. (A) is an enlarged cross-sectional view of the vicinity of the male screw member when the screw of the male screw member of FIG. 2 is a single thread, and (b) is a male screw member when the thread of the male screw member of FIG. Enlarged sectional view of the vicinity The expanded sectional view which shows the chain tensioner of 2nd Embodiment of this invention The figure which shows the result of having done the test which compares the damper performance about the sample of the plural chain tensioners where the air bleeding amount differs

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chain tensioner 9 Cylinder 10 Plunger 12 Female thread 13 Male thread 14 Screw rod 15 Rod seat 16 Pressure side flank 17 Play side flank 18 Return spring 20 Pressure chamber 21 Oil supply passage 22 Check valve 24 Through hole 25 Female thread 26 Male thread member 26a Head 27 Spring Washer 31 Chain tensioner 32 Housing groove 33 Register ring 34 Circumferential groove 35 Tapered surface 36 Stopper surface

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). (18) is provided, an oil supply passage (21) for introducing hydraulic oil is provided in the pressure chamber (20) surrounded by the plunger (10) and the cylinder (9), and an outlet of the oil supply passage (21) is provided. In a chain tensioner provided with a check valve (22) for preventing backflow of hydraulic oil,
A through hole (24) communicating the pressure chamber (20) and the outside air is formed in the cylinder (9), and a female screw (25) formed on the inner periphery of the through hole (24) has a continuous pore. The screw member (26) made of a material is screwed, and the air mixed in the pressure chamber (20) is spirally formed between the male screw member (26) and the female screw (25). A chain tensioner characterized in that it discharges to the outside air in parallel with the continuous pores inside the male screw member (26).   The chain tensioner according to claim 1, wherein the screw of the male screw member (26) is a multi-threaded screw.   The amount of air released by combining the screw gap between the male screw member (26) and the female screw (25) and the continuous pores inside the male screw member (26) is set to 60 to 30 per 30 seconds under a 0.1 MPa load condition. The chain tensioner according to claim 1 or 2, which is set in a range of 600 cc.   The chain tensioner according to claim 3, wherein the air bleeding amount is set in a range of 400 to 600 cc.   The chain tensioner according to any one of claims 1 to 4, wherein a sintered metal is used as the porous material.   The chain tensioner according to any one of claims 1 to 4, wherein a sintered resin is used as the porous material.   The male screw member (26) has a head (26a) having a diameter larger than that of the through hole (24), and a part of the circumference is provided between the head (26a) and the cylinder (9). The chain tensioner according to any one of claims 1 to 6, wherein a spring washer (27) having a separated shape is incorporated.   The chain tensioner according to any one of claims 1 to 7, wherein a nominal diameter of the male screw member (26) is set in a range of M3 to M8.   The plunger (10) is formed in a bottomed cylindrical shape with an opening end into the cylinder (9), and is externally engaged with a female screw (12) formed on the inner periphery of the plunger (10). And a projecting end of the screw rod (14) from the plunger (10) is supported by a rod sheet (15) provided in the cylinder (9), and the male screw ( 13) and the female thread (12) are such that the flank angle of the pressure side flank (16) 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 (17). 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.   A register ring (33) for elastically fastening the outer periphery of the plunger (10) is accommodated in an annular accommodating groove (32) formed on the inner periphery of the cylinder (9), and the register ring (33) is The plunger (10) is engaged with a circumferential groove (34) formed at a constant interval in the axial direction on the outer periphery of the plunger (10), 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 (33) is increased to allow the plunger (10) to move, and the plunger (10) is connected to the cylinder (9). A stopper surface (36) is provided for locking the register ring (33) 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.

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