JP2010144895A - Chain tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the need for a diameter expansion operation piece of a coming-off preventive ring, and to reduce an outside diameter of a cylinder. <P>SOLUTION: This chain tensioner 1 is constituted to insert the cylinder 9 into a tensioner attaching hole 12 of an engine cover 11, to be fixed, to insert slidably a plunger 10 into the cylinder 9, to provide a return spring 23 for energizing the plunger 10 toward a direction projected from the cylinder 9, to assemble the C-type coming-of preventive ring 32 contacting with an inside of a coming-off preventive ring storage groove 31 formed in an inner circumference of the cylinder 9, while holding a tightening margin in an outer circumference of the plunger 10, and to form a coming-off preventive ring engaging groove 33 engaged with the coming-off preventive ring 32 to prevent the plunger 10 from coming off from the cylinder 9, in an outer circumference of an insertion portion of the plunger 10 into the cylinder 9, both ends of the coming-off preventive ring 32 are formed into end part shapes along a circumferential direction, and a tapered face 36 is formed in an insertion end outer circumference of inserting the plunger 10 into the cylinder 9. <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 cylindrical cylinder having one end opened and the other end closed is inserted and fixed in the engine cover tensioner mounting hole with the open end facing into the engine cover, The plunger is slidably inserted in the cylinder in the axial direction, and the plunger is formed in a bottomed cylindrical shape having an insertion end into the cylinder, and is engaged with a female screw formed on the inner periphery of the plunger. A screw rod having a male screw on the outer periphery is provided, and a return spring for biasing the plunger in a direction protruding from the cylinder is provided by bringing a protruding end of the screw rod from the plunger into contact with a rod seat provided in the cylinder, A device in which a chain guide is pressed by a protruding end of a plunger from a cylinder is known (Patent Document 1). .

  When the chain tension is reduced during engine operation, the chain tensioner moves in the direction in which the plunger protrudes from the cylinder (hereinafter referred to as “protruding direction”) by the urging force of the return spring, and absorbs slack in the chain.

  On the other hand, when the chain tension increases during engine operation, the plunger moves in the direction in which the plunger is pushed into the cylinder by the chain tension (hereinafter referred to as the “push-in direction”) to absorb the chain tension. At this time, the screw rod is gradually rotated by the vibration of the chain and allows the plunger to move in the pushing direction.

  Since the chain does not vibrate when the engine is stopped, the plunger's female screw is received by the screw rod's male screw even if the chain tension increases due to the cam stop position, preventing the plunger from moving in the pushing direction. . Therefore, when the engine is restarted, the chain is hardly slackened, and the engine can be started smoothly.

  When the chain tensioner is detached from the engine cover, the plunger protrudes from the cylinder by the urging force of the return spring. Therefore, if the mechanism for preventing the plunger from coming off from the cylinder is not provided, the plunger may drop from the cylinder.

Therefore, in order to prevent the plunger from falling off, the chain tensioner incorporates a C-shaped retaining ring that comes into contact with the outer periphery of the plunger with a tightening margin in a retaining ring receiving groove formed on the inner periphery of the cylinder. When the plunger protrudes from the cylinder, the retaining ring engages with a retaining ring engagement groove on the outer periphery of the plunger, and the engagement prevents the plunger from coming off the cylinder.
JP 2008-57725 A

  As shown in FIGS. 11 and 12, the chain tensioner includes a C-shaped ring portion 51A and a pair of diameter-expanding operation pieces 51B and 51B extending radially outward from both ends of the ring portion 51A. A retaining ring 51 is used. The diameter-enlarging operation piece 51 </ b> B is used to prevent the plunger 52 from interfering with the retaining ring 51 when the plunger 52 is inserted into the cylinder 53 and the chain tensioner 50 is assembled. It is possible.

  Further, the cylinder 53 is formed with a notch 54 for accommodating the diameter expansion operation piece 51B. Here, if the tip of the diameter expanding operation piece 51B protrudes outside the outer diameter of the cylinder 53, the tip of the diameter expanding operation piece 51B is the engine when the cylinder 53 is inserted into the tensioner mounting hole 56 of the engine cover 55. Since it interferes with the cover 55, in order to prevent this interference, the radial thickness of the cylinder 53 is increased so that the tip of the diameter expanding operation piece 51 </ b> B fits within the outer diameter of the cylinder 53.

  As described above, the chain tensioner 50 needs to have a large thickness in the radial direction of the cylinder 53. Therefore, the cylinder 53 has a large outer diameter and a wide installation space.

  The problem to be solved by the present invention is to reduce the outer diameter of the cylinder without requiring the diameter-enlarging operation piece of the retaining ring.

  In order to solve the above-mentioned problem, when the plunger is inserted into the cylinder, the retaining ring is pushed and widened by the tapered surface formed on the outer periphery of the insertion end of the plunger into the cylinder. In this way, when the plunger is inserted into the cylinder, it is possible to prevent interference between the plunger and the retaining ring without expanding the retaining ring. There is no need to provide a piece. Therefore, the outer diameter of the cylinder can be reduced by making both ends of the retaining ring end shapes along the circumferential direction.

  The retaining ring uses a metal wire bent in an elliptical shape, the long diameter portion of the retaining ring is fitted to the inner diameter of the retaining ring receiving groove, and the short diameter portion of the retaining ring is the outer periphery of the plunger. Can be contacted with a margin. In this way, the retaining ring is positioned by the fitting of the long diameter portion. Therefore, when the plunger is inserted into the cylinder, the center of the plunger and the center of the retaining ring are difficult to shift, and the plunger is smoothly inserted into the retaining ring. Can be introduced.

  When an oval retaining ring is used, it is preferable that the retaining ring is a C-shape with the circumference cut off by a long diameter portion. In this way, when the plunger is inserted into the cylinder, it comes into contact with the taper surface of the plunger at a portion where the retaining ring is not separated, so that the diameter expansion operation of the retaining ring becomes smoother.

  In addition, the retaining ring uses a metal wire bent into a polygonal shape, the corner of the retaining ring is fitted to the inner diameter of the retaining ring receiving groove, and the side of the retaining ring is connected to the plunger. The outer periphery can be brought into contact with a tightening margin. Even in this case, the retaining ring is positioned by the fitting of the corners. Therefore, when the plunger is inserted into the cylinder, the center of the plunger and the center of the retaining ring are not easily displaced, and the plunger is placed in the retaining ring. It can be introduced smoothly.

  When a polygonal retaining ring is used, it is preferable that the retaining ring is C-shaped with the periphery cut off at the corners. In this way, when the plunger is inserted into the cylinder, it comes into contact with the taper surface of the plunger at a portion where the retaining ring is not separated, so that the diameter expansion operation of the retaining ring becomes smoother.

  The cross-sectional shape of the retaining ring can be a circle. In this way, when the plunger is inserted into the cylinder, the retaining ring comes into stable contact with the tapered surface of the plunger, and the diameter expansion operation of the retaining ring becomes smooth.

  It is preferable that the outer diameter of the small diameter end of the tapered surface be smaller than the inscribed circle diameter of the retaining ring in a natural state where the diameter is not increased and deformed. In this way, the plunger can be smoothly introduced into the retaining ring when the plunger is inserted into the cylinder.

  The inclination of the tapered surface can be set to 20 ° or less. In this way, when the plunger is inserted into the cylinder, the retaining ring is surely pushed and expanded by the wedge effect of the tapered surface, and the diameter expansion operation of the retaining ring becomes smooth.

  Also, the set ring housing is provided with a step on the open end side of the inner ring periphery of the cylinder, so that the inner diameter of the open end side of the cylinder is smaller than the inner diameter of the closed end side of the cylinder. A groove is formed, and a set ring including a C-shaped ring portion and a pair of diameter-reducing operation pieces extending from both ends of the ring portion is incorporated in the set-ring receiving groove, and the pair of diameter-reducing operation pieces are The cylinder is accommodated in a notch formed in the cylinder so as to cross the set ring accommodation groove, and the plunger is pushed into the cylinder by engaging with the set ring in an elastically reduced diameter state on the outer periphery of the plunger. A set ring engagement groove is formed, and the set ring is expanded in the set ring receiving groove by an operation of further pushing the plunger into the cylinder. It can be made to release the engagement.

  The diameter reducing operation piece of the set ring is preferably formed so as to extend in the axial direction from both ends of the ring portion. In this way, the diameter-reducing operation piece is difficult to protrude outside the outer diameter of the cylinder, so that the outer diameter of the cylinder can be kept small.

  The notch may be formed so as to cross both the set ring receiving groove and the retaining ring receiving groove, but is preferably formed so as to cross only the set ring receiving groove. If it does in this way, the sliding area of a cylinder and a plunger can be ensured and the attitude | position of a cylinder will be stabilized.

  Since the chain tensioner of this invention makes the both ends of the retaining ring into the edge part shape along the circumferential direction, the outer diameter of a cylinder can be restrained small.

  FIG. 1 shows a chain transmission device incorporating a chain tensioner 1 according to an 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.

  As shown in FIG. 2, the chain tensioner 1 includes a cylindrical cylinder 9 that is open at one end and closed at the other end, and a plunger 10 that is slidably inserted into the cylinder 9 in the axial direction.

  The cylinder 9 is inserted into the tensioner mounting hole 12 of the engine cover 11 with the opening end facing the engine cover 11. The cylinder 9 has a flange 13 integrally formed on the outer periphery thereof and is fastened to the outer surface of the engine cover 11 with bolts 14, and is fixed to the engine cover 11 by the tightening. An annular gasket 15 is sandwiched between the flange 13 and the engine cover 11.

  The plunger 10 is formed in a bottomed cylindrical shape whose opening end into the cylinder 9 is open, and a female screw 16 is formed on the inner periphery thereof. A screw rod 18 having a male screw 17 that engages with the female screw 16 on the outer periphery is incorporated in the plunger 10. One end of the screw rod 18 protrudes from the plunger 10, and the protruding end is in contact with a rod sheet 19 provided in the cylinder 9.

  The male screw 17 and the female screw 16 have a sawtooth shape in which the flank angle of the pressure side flank 20 that receives pressure when a load in the direction of pushing the screw rod 18 into the plunger 10 is applied is larger than the flank angle of the play side flank 21. When the load in the direction in which the screw rod 18 is pushed into the plunger 10 is statically applied, the screw rod 18 is rotated by the frictional resistance between the pressure side flank 20, 20 of the male screw 17 and the female screw 16. When the load in the direction in which the screw rod 18 protrudes from the plunger 10 is statically blocked, the screw rod 18 is allowed to rotate by sliding between the play side flank 21, 21 of the male screw 17 and the female screw 16. It is like that.

  A return spring 23 is incorporated in the pressure chamber 22 surrounded by the cylinder 9 and the plunger 10. One end of the return spring 23 is supported by the screw rod 18, and the other end presses the plunger 10 via the spring seat 24, and the plunger 10 is biased in a direction protruding from the cylinder 9 by the pressing. . Further, the plunger 10 is also urged in a direction protruding from the cylinder 9 by an assist spring 25 incorporated between the plunger 10 and the rod seat 19. The plunger 10 is in contact with the chain guide 8 at the protruding end from the cylinder 9.

  An oil supply passage 26 for introducing hydraulic oil into the pressure chamber 22 is formed in the cylinder 9. The oil supply passage 26 has an inlet connected to an oil supply pump (not shown), and introduces hydraulic oil fed from the oil supply pump into the pressure chamber 22. A check valve 27 is provided at the outlet of the oil supply passage 26 to prevent the backflow of hydraulic oil from the pressure chamber 22 to the oil supply passage 26.

  The cylinder 9 is formed with a relief passage 28 that communicates from the pressure chamber 22 through the inside of the flange 13 to the mating surface of the flange 13 with respect to the engine cover 11. A relief valve 29 that is opened when the pressure in the pressure chamber 22 becomes higher than a preset pressure is incorporated in the relief passage 28. In addition, a gap that allows the relief passage 28 to communicate with the engine cover 11 is formed between the flat surface 30 formed on the outer periphery of the portion inserted into the tensioner mounting hole 12 of the cylinder 9 and the inner periphery of the tensioner mounting hole 12. ing.

  A retaining ring receiving groove 31 extending in the circumferential direction is formed on the inner periphery of the open end of the cylinder 9, and a retaining ring 32 is incorporated in the retaining ring receiving groove 31. The retaining ring 32 is in an elastically expanded state, and is in contact with the outer periphery of the plunger 10 with a tightening margin. Here, as shown in FIG. 4, the retaining ring 32 is formed in a C shape in which a part of the circumference is cut off, and the diameter can be elastically increased by increasing the distance between both ends. .

  As shown in FIG. 3, a retaining ring engaging groove 33 that engages with the retaining ring 32 when the plunger 10 protrudes from the cylinder 9 is formed on the outer periphery of the plunger 10. In the retaining ring engaging groove 33, a stopper surface 34 that rises on the insertion end side of the plunger 10 into the cylinder 9 and a guide surface 35 that rises on the protruding end side of the plunger 10 from the cylinder 9 are provided. .

  The stopper surface 34 has a steep rising angle, and receives the retaining ring 32 when the plunger 10 protrudes from the cylinder 9 to prevent the plunger 10 from coming off the cylinder 9. On the other hand, the guide surface 35 has a gentle rise angle, and when the plunger 10 is inserted into the cylinder 9, the retaining ring 32 is expanded to allow the plunger 10 to move.

  As shown in FIG. 9, a tapered surface 36 is formed on the outer periphery of the insertion end of the plunger 10 into the cylinder 9. When the plunger 10 is inserted into the cylinder 9 and the chain tensioner 1 is assembled, the taper surface 36 expands the retaining ring 32 to expand its diameter and prevents the plunger 10 and the retaining ring 32 from interfering with each other. When the inclination of the taper surface 36 is set to 20 ° or less, the retaining ring 32 can be surely expanded by the wedge effect of the tapered surface 36 when the plunger 10 is inserted into the cylinder 9. The diameter expansion operation becomes smooth.

  A set ring accommodating groove 37 is formed on the inner end of the cylinder 9 on the open end side of the retaining ring accommodating groove 31, and a set ring 38 is incorporated in the set ring accommodating groove 37. The set ring receiving groove 37 is provided with a step so that the inner diameter on the open end side of the cylinder 9 is smaller than the inner diameter on the closed end side of the cylinder 9.

  As shown in FIG. 5, the set ring 38 includes a C-shaped ring part 38 </ b> A with part of the circumference cut off, and a pair of diameter-reducing operation pieces 38 </ b> B and 38 </ b> B extending in the axial direction from both ends of the ring part 38 </ b> A. Thus, the diameter can be elastically reduced by reducing the interval between the diameter reducing operation pieces 38B. As shown in FIG. 3, the diameter reducing operation piece 38 </ b> B is housed in a notch 39 formed in the cylinder 9 so as to cross the set ring housing groove 37. The notch 39 is formed so as to cross only the set ring receiving groove 37 among the set ring receiving groove 37 and the retaining ring receiving groove 31.

  As shown in FIG. 2, a set ring engagement groove 40 that matches the set ring receiving groove 37 when the plunger 10 is pushed into the cylinder 9 is formed on the outer periphery of the plunger 10.

  In the state where the set ring receiving groove 37 and the set ring engaging groove 40 are matched, the set ring 38 is held in the set ring receiving groove 37 by pinching the diameter reducing operation piece 38B and reducing the diameter of the ring portion 38A. Can be engaged with the set ring engagement groove 40 at a position on the open end side of the cylinder 9, and by this engagement, the plunger 10 is kept pushed into the cylinder 9 (hereinafter referred to as “initial setting”). can do.

  At this time, the set ring 38 is elastically reduced in diameter, and the initial setting of the plunger 10 can be released by further pushing the plunger 10 into the cylinder 9. At this time, the set ring 38 moves from the open end side of the cylinder 9 to the closed end side in the set ring receiving groove 37 and expands in the set ring receiving groove 37 to engage with the set ring engaging groove 40. Is released.

  For example, the chain tensioner 1 is assembled to the engine cover 11 as follows.

  First, the plunger 10 is pushed into the cylinder 9 for initial setting. Next, the cylinder 9 is inserted into the tensioner mounting hole 12 of the engine cover 11. At this time, since both ends of the retaining ring 32 have end portions along the circumferential direction, both ends of the retaining ring 32 do not protrude outside the outer diameter of the cylinder 9, and the retaining ring 32 is There is no possibility of interference with the engine cover 11. Further, since the diameter reducing operation piece 38B of the set ring 38 is formed so as to extend in the axial direction, the diameter reducing operation piece 38B does not protrude outside the outer diameter of the cylinder 9, and the set ring 38 is There is no possibility of interference with the engine cover 11. After the cylinder 9 is inserted into the tensioner mounting hole 12, the flange 13 is tightened with the bolt 14 to fix the cylinder 9 to the engine cover 11, and the assembly of the chain tensioner 1 is completed.

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

  When the tension of the chain 6 becomes smaller during the operation of the engine, the plunger 10 moves in the protruding direction by the urging force of the return spring 23, and the slack of the chain 6 is absorbed. At this time, the check valve 27 is opened, and the hydraulic oil supplied from the oil pump flows into the pressure chamber 22 through the oil supply passage 26, so that 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 the forward and backward movements within the range of the axial clearance between the female screw 16 and the male screw 17 due to the vibration of the chain 6. Further, since the hydraulic oil in the pressure chamber 22 flows out through the leak gap 41 between the sliding surface 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 the camshaft 4. In this case, since the chain 6 does not vibrate, the internal thread 16 of the plunger 10 is received by the external thread 17 of the screw rod 18. Ten positions are fixed. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  In the chain tensioner 1, when the plunger 10 is inserted into the cylinder 9 and the chain tensioner 1 is assembled, the taper surface 36 of the plunger 10 expands the retaining ring 32 by expanding the retaining ring 32. Even if the diameter is not operated, interference between the plunger 10 and the retaining ring 32 can be prevented, and there is no need to provide a diameter-enlarging operation piece at both ends of the retaining ring 32. Therefore, the outer diameter of the cylinder 9 can be reduced by making both ends of the retaining ring 32 end shapes along the circumferential direction.

  Further, the chain tensioner 1 is formed so that the diameter-reducing operation piece 38B of the set ring 38 extends in the axial direction. Therefore, the diameter-reducing operation piece 38B hardly protrudes outside the outer diameter of the cylinder 9, and the cylinder tensioner 1 The outer diameter of 9 can be kept small.

  The notch 39 of the cylinder 9 may be formed so as to cross both the set ring receiving groove 37 and the retaining ring receiving groove 31, but as shown in the above embodiment, only the set ring receiving groove 37 is crossed. It is preferable to form it. If it does in this way, the sliding area of the cylinder 9 and the plunger 10 can be ensured, and the attitude | position of the cylinder 9 will be stabilized.

  As shown in FIG. 4, the retaining ring 32 may be formed by bending a metal wire into a perfect circle. However, as shown in FIGS. 6 (a) and 6 (b), the metal wire is formed into an elliptical shape. It is preferable to use a bent portion of which the long diameter portion 32a is fitted into the inner diameter of the retaining ring receiving groove 31 and the short diameter portion 32b is in contact with the outer periphery of the plunger 10 with a tightening margin. In this way, the retaining ring 32 is positioned by the fitting of the long diameter portion 32a. Therefore, when the plunger 10 is inserted into the cylinder 9, the center of the plunger 10 and the center of the retaining ring 32 are not easily displaced, and the plunger 10 Can be smoothly introduced into the retaining ring 32.

  When the oval retaining ring 32 is used in this way, as shown in FIG. 6 (a), it is preferable to use a C-shape with the circumference cut off by the long diameter portion 32a. In this way, when the plunger 10 is inserted into the cylinder 9, since the retaining ring 32 comes into contact with the tapered surface 36 at a portion where the retaining ring 32 is not separated, the diameter expansion operation of the retaining ring 32 becomes smoother.

  As shown in FIGS. 7A and 7B, the retaining ring 32 uses a metal wire bent in a triangular shape, and the corner portion 32 c is fitted to the inner diameter of the retaining ring receiving groove 31. The side portion 32d may contact the outer periphery of the plunger 10 with a tightening margin. Even if it does in this way, since the retaining ring 32 is positioned by the fitting of the corner portion 32c, when the plunger 10 is inserted into the cylinder 9, the center of the plunger 10 and the center of the retaining ring 32 are not easily displaced, and the plunger 10 can be smoothly introduced into the retaining ring 32.

  When the triangular retaining ring 32 is used as described above, it is preferable to use a C-shape with the corners 32c cut off as shown in FIG. 7A. In this way, when the plunger 10 is inserted into the cylinder 9, since the retaining ring 32 comes into contact with the tapered surface 36 at a portion where the retaining ring 32 is not separated, the diameter expansion operation of the retaining ring 32 becomes smoother.

  Similarly, as shown in FIGS. 8A and 8B, a metal wire bent into a square shape is used as the retaining ring 32, and the corner portion 32 c is fitted into the inner diameter of the retaining ring receiving groove 31. In addition, the side portion 32d may contact the outer periphery of the plunger 10 with a tightening margin.

  The cross-sectional shape of the retaining ring 32 is preferably circular as shown in FIG. In this way, when the plunger 10 is inserted into the cylinder 9, the retaining ring 32 stably contacts the tapered surface 36 of the plunger 10, and the diameter expansion operation of the retaining ring 32 becomes smooth.

  As shown in FIG. 10B, the outer diameter of the tapered end of the tapered surface 36 is preferably smaller than the inscribed circle diameter of the retaining ring 32 in the natural state in which the diameter is not expanded. In this way, the plunger 10 can be smoothly introduced into the retaining ring 32 when the plunger 10 is inserted into the cylinder 9.

Front view showing a chain transmission apparatus incorporating a chain tensioner according to an embodiment of the present invention 1 is an enlarged cross-sectional view near the chain tensioner of FIG. The expanded sectional view of the open end vicinity of the cylinder which shows the state which the plunger shown in FIG. 2 protruded from the cylinder Sectional view along line IV-IV in FIG. Sectional view along line VV in FIG. FIGS. 5A and 5B are diagrams showing a modification example in which the retaining ring shown in FIG. 4 has an elliptical shape, wherein FIG. 5A is a diagram showing a modification example in which the circumference is cut off by the long diameter part, and FIG. Illustration showing an example It is a figure which shows the modification which made the retaining ring shown in FIG. 4 triangular, (a) is a figure which shows the modification which cut | disconnected the periphery at the corner | angular part, (b) is the modification which cut | disconnected the periphery at the edge part Figure showing It is a figure which shows the modification which made the retaining ring shown in FIG. 4 square shape, (a) is a figure which shows the modification which cut | disconnected the periphery at the corner | angular part, (b) is the modification which cut | disconnected the periphery at the edge part Figure showing The expanded sectional view of the open end vicinity of a cylinder which shows the process in which the plunger shown in FIG. 2 is inserted in a cylinder 9A is an enlarged cross-sectional view in the vicinity of the tapered surface in FIG. 9, and FIG. 9B is an enlarged cross-sectional view showing a modification of the tapered surface in FIG. Front view showing a conventional chain tensioner Sectional drawing along the XII-XII line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chain tensioner 9 Cylinder 10 Plunger 11 Engine cover 12 Tensioner attachment hole 16 Female screw 17 Male screw 18 Screw rod 19 Rod seat 23 Return spring 31 Retaining ring accommodation groove 32 Retaining ring 32a Long diameter part 32b Short diameter part 32c Corner part 32d Side part 33 Stop ring engagement groove 36 Tapered surface 37 Set ring receiving groove 38 Set ring 38A Ring portion 38B Reduced diameter operation piece 39 Notch 40 Set ring engagement groove

Claims (11)

The cylindrical cylinder (9) with one end opened and the other end closed is inserted and fixed into the tensioner mounting hole (12) of the engine cover (11) with the open end oriented in the engine cover (11). The plunger (10) is inserted into the cylinder (9) so as to be slidable in the axial direction, and the plunger (10) is formed into a bottomed cylindrical shape with an insertion end into the cylinder (9) 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 protruding end of the screw rod (18) from the plunger (10) Is provided in contact with a rod seat (19) provided in the cylinder (9), and a return spring (23) for urging the plunger (10) in a direction protruding from the cylinder (9) is provided. A C-shaped retaining ring (32) that comes into contact with the outer periphery of the plunger (10) with a tightening margin is incorporated into a retaining ring receiving groove (31) formed on the inner periphery of the plunger (10), and the cylinder (9) of the plunger (10) A stopper that prevents the plunger (10) from coming off the cylinder (9) by engaging with the retaining ring (32) when the plunger (10) protrudes from the cylinder (9) on the outer periphery of the insertion portion. In the chain tensioner formed with the ring engaging groove (33),
Both ends of the C-shaped retaining ring (32) are end-shaped along the circumferential direction, and the plunger (10) is placed on the outer periphery of the insertion end of the plunger (10) into the cylinder (9). A chain tensioner characterized in that a taper surface (36) is formed for expanding the diameter of the retaining ring (32) by expanding the retaining ring (32) when inserted into the chain tensioner.   The retaining ring (32) is formed by bending a metal wire into an elliptical shape, and the long diameter portion (32a) of the retaining ring (32) is fitted to the inner diameter of the retaining ring receiving groove (31), The chain tensioner according to claim 1, wherein the short diameter portion (32b) of the retaining ring (32) is in contact with the outer periphery of the plunger (10) with tightening allowance.   The chain tensioner according to claim 2, wherein the retaining ring (32) is a C-type having a circumference cut by a long diameter portion (32a).   The retaining ring (32) is formed by bending a metal wire into a polygonal shape, and a corner (32c) of the retaining ring (32) is fitted to an inner diameter of the retaining ring receiving groove (31), The chain tensioner according to claim 1, wherein the side portion (32d) of the retaining ring (32) contacts the outer periphery of the plunger (10) with a tightening margin.   The chain tensioner according to claim 4, wherein the retaining ring (32) has a C-shape with its periphery cut off at the corner (32c).   The chain tensioner according to any one of claims 1 to 5, wherein the retaining ring (32) has a circular cross-sectional shape.   The outer diameter of the small-diameter end of the tapered surface (36) is smaller than the inscribed circle diameter of the retaining ring (32) in a natural state that is not expanded and deformed. Chain tensioner.   The chain tensioner according to any one of claims 1 to 7, wherein an inclination of the tapered surface (36) is set to 20 ° or less.   The inner diameter of the cylinder (9) is closer to the open end than the retaining ring receiving groove (31), and the inner diameter of the cylinder (9) is smaller than the inner diameter of the cylinder (9) on the closed end side. A set ring receiving groove (37) having a step is formed, and a C-shaped ring portion (38A) and a pair extending from both ends of the ring portion (38A) are formed in the set ring receiving groove (37). A set ring (38) composed of a reduced diameter operation piece (38B) was incorporated, and the pair of reduced diameter operation pieces (38B) was formed in the cylinder (9) so as to cross the set ring receiving groove (37). The plunger (10) is pushed into the cylinder (9) by engaging with the set ring (38) in an elastically contracted state on the outer periphery of the plunger (10). Setrin to hold An engagement groove (40) is formed, and when the plunger (10) is further pushed into the cylinder (9), the set ring (38) expands in the set ring receiving groove (37) and engages with the set ring. The chain tensioner according to any one of claims 1 to 8, wherein the engagement with the groove (40) is released.   The chain tensioner according to claim 9, wherein the diameter-reducing operation piece (38B) is formed so as to extend axially from both ends of the ring portion (38A).   The said notch (39) was formed so that only a set ring accommodation groove (37) might be crossed among the said set ring accommodation groove (37) and a retaining ring accommodation groove (31). Chain tensioner.

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