JP2016098887A - Chain tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner which inserts a tool into a chain cover from a service hole formed at the chain cover, and is facilitated in an operation for diameter-expanding a ring part of a register ring by using the tool.SOLUTION: A register ring 21 is composed of a ring part 22 having a shape in which a part of a circumference is cut and separated, and a pair of operation pieces 23, 24 which are arranged at both ends of the ring part for diameter-expanding the ring part 22. The pair of the operation pieces 23, 24 are exposed to the outside of a cylinder 9 from a notch 30 of the cylinder 9. The operation piece 23 has a length penetrating the notch 30, and protruding to an outside diameter side of the cylinder 9, and can diameter-expand the ring part 22 by press-moving a tool abutment part 23b of the operation piece 23 by a tip of a rod-shaped tool 35. A tool guide piece 36 which slide-supports a side face of the tool 35 when press-moving the operation piece 23 by the tip of the tool 35 is arranged at an external periphery of the cylinder 9.SELECTED DRAWING: Figure 5

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 (hereinafter referred to as “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 cylinder having one end opened and the other end closed, a plunger inserted in the cylinder so as to be slidable in the axial direction, and a direction in which the plunger protrudes from the cylinder One having a return spring to be urged is known (for example, Patent Documents 1 and 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. On the other hand, when the chain tension is reduced during engine operation, the plunger moves in the direction of protruding from the cylinder (hereinafter referred to as “protruding direction”) by the biasing force of the return spring to absorb the slack of the chain.

  When the engine stops, the chain tension may increase depending on the stop position of the camshaft. At this time, if the plunger moves greatly in the pushing direction in accordance with the tension of the chain, the chain will be greatly loosened when the engine is started thereafter, and the chain may flutter or jump.

  Therefore, the chain tensioners of Patent Documents 1 and 2 employ a no-back mechanism in order to limit the movement of the plunger while the engine is stopped. The no-back mechanism includes a plurality of axially adjacent circumferential grooves provided on the outer periphery of the plunger, a ring receiving groove formed on the inner periphery of the cylinder, and a register ring received in the ring receiving groove. The register ring tightens the circumferential groove on the outer periphery of the plunger.

  Each circumferential groove on the outer periphery of the plunger has a tapered surface that allows the plunger to move by expanding the diameter of the register ring when a load is applied in a direction that causes the plunger to protrude from the cylinder, and a direction in which the plunger is pushed into the cylinder When the load is applied, the register ring is locked to restrict the movement of the plunger.

JP 2001-355691 A JP 2002-5250 A

  When the chain tensioner is assembled by inserting a plunger into the cylinder, or when the plunger is pulled out from the cylinder and disassembled, the diameter of the register ring needs to be increased. In order to facilitate the diameter expansion operation of the register ring, the register ring has a configuration in which a pair of operation pieces are provided crossed at both ends of the ring portion having a shape in which a part of the circumference is cut off. The diameter of the ring portion can be increased by pinching the pair of operation pieces.

  By the way, when performing engine maintenance or the like, it is necessary to temporarily relax the timing chain. At this time, by expanding the diameter of the ring portion of the register ring, the restriction on the movement of the plunger by the no-back mechanism is released, and when the plunger is pushed into the cylinder in this state, the chain loosens in accordance with the movement of the plunger. .

  In the work of loosening the chain, the diameter expansion operation of the register ring is performed by inserting a tool into the chain cover from a service hole provided in the chain cover and pushing and moving the operation piece of the register ring with the tip of the tool, for example. However, it is difficult to push and move the operation piece of the registering ring with the tip of the tool in a groping state (that is, a state where the chain tensioner is not visible to the operator). Therefore, while a tool is inserted into the service hole of the chain cover and the position of the operating piece of the register ring is searched with the tool, the side surface of the tool may come into contact with the operating piece of the register ring, and the register ring may be plastically deformed. was there. If the register ring is plastically deformed, the no-back mechanism may not function normally.

  The problem to be solved by the present invention is to provide a chain tensioner in which a tool is inserted into a chain cover from a service hole provided in the chain cover, and an operation of expanding the ring portion of the register ring with the tool is easy. is there.

In order to solve the above problems, the present invention provides a chain tensioner having the following configuration.
A cylindrical cylinder with one end open and the other end closed;
A plunger inserted into the cylinder so as to be slidable in the axial direction;
A return spring that biases the plunger in a direction protruding from the cylinder;
A plurality of axially adjacent circumferential grooves provided on the outer periphery of the plunger;
A ring receiving groove formed on the inner periphery of the cylinder;
A register ring that is housed in the ring housing groove and tightens the circumferential groove on the outer periphery of the plunger;
The register ring is composed of a ring part with a part of the circumference cut off, and a pair of operation pieces for expanding the diameter of the ring part provided at both ends of the ring part,
Each of the circumferential grooves includes a tapered surface that expands the diameter of the ring portion of the register ring and allows the plunger to move when a load in a direction in which the plunger protrudes from the cylinder is applied. A stopper surface that locks the ring portion of the register ring and restricts the movement of the plunger when a load in the direction to be pushed into is applied,
In the chain tensioner, the cylinder has a notch that intersects the ring receiving groove and penetrates the cylinder in the radial direction, and the pair of operation pieces are exposed to the outside of the cylinder from the notch.
At least one of the pair of operation pieces has a length that penetrates the notch and protrudes toward the outer diameter side of the cylinder, and a protruding portion of the operation piece toward the outer diameter side of the cylinder is formed by a rod-shaped tool. It is possible to increase the diameter of the ring by pushing and moving at the tip.
A chain tensioner, wherein a tool guide piece for slidingly supporting a side surface of the tool when the operation piece is pushed and moved by a tip of the tool is provided on an outer periphery of the cylinder.

  In this way, when the operation piece is pushed and moved by the tip of the tool, the side surface of the tool is slidably supported by the tool guide piece provided on the outer periphery of the cylinder, so that the tip of the tool can be easily aligned with the position of the operation piece. In addition, it is easy to push and move the operation piece with the tip of the tool. Therefore, it is easy to insert a tool into the chain cover from the service hole provided in the chain cover and to enlarge the diameter of the ring portion of the register ring with the tool.

  The tool guide piece may be provided so as to face a protruding portion of the operation piece toward the outer diameter side of the cylinder. At this time, as the tool guide piece, it is preferable to employ a tool guide hole having a tool insertion hole through which the tool is inserted on a surface facing the protruding portion of the operation piece.

  In this case, since the tool guide piece guards the periphery of the operation piece, the side surface of the tool can be prevented from coming into contact with the operation piece of the register ring, and the register ring can be prevented from being plastically deformed. it can.

  It is preferable to provide a taper surface that gradually expands from the side closer to the operation piece toward the side farther from the inner periphery of the tool insertion hole.

  If it does in this way, since the taper surface of the inner periphery of a tool penetration hole guides the tip of a tool, the operation | work which aligns the front-end | tip of a tool to the position of an operation piece becomes smoother.

  It is preferable that the tool insertion hole has an axial width that overlaps the entire axial width of the ring receiving groove.

  This makes it possible to push and move the operating piece of the register ring with the tip of the tool inserted through the tool insertion hole, regardless of the position of the register ring in the ring receiving groove.

  Since the chain tensioner of the present invention has a tool guide piece that slides and supports the side surface of the tool on the outer periphery of the cylinder, when the operation piece is pushed and moved by the tip of the tool, the tip of the tool is easily aligned with the position of the operation piece. Also, it is easy to push and move the operating piece with the tip of the tool. Therefore, it is easy to insert a tool into the chain cover from the service hole provided in the chain cover and to enlarge the diameter of the ring portion of the register ring with the tool.

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 of the chain tensioner shown in FIG. Sectional view along line III-III in FIG. Enlarged view of the vicinity of the tool guide piece of the chain tensioner shown in FIG. Sectional drawing which shows the operation | work which pushes and moves the operation piece of the register ring shown in FIG. 3 with the front-end | tip of the tool inserted from the service hole The figure which shows the modification of the tool guide piece shown in FIG. The figure which shows the other modification of the tool guide piece shown in FIG. The figure which shows the further another modification of the tool guide piece shown in FIG. Sectional drawing which shows the operation which pushes the operation piece of a register ring with the front-end | tip of the tool inserted from the service hole in the chain tensioner of the comparative example without a tool guide piece.

  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 integrally formed of metal (for example, aluminum alloy). As shown in FIG. 1, the cylinder 9 is fixed to the side surface of the engine block 13 (see FIG. 3) by tightening bolts 12 into a plurality of mounting pieces 11 formed integrally on the outer periphery of the cylinder 9. .

  As shown in FIG. 2, the plunger 10 is formed in a bottomed cylindrical shape whose opening end into the cylinder 9 is open. An oil supply passage 15 communicating with a pressure chamber 14 surrounded by the cylinder 9 and the plunger 10 is formed at the end of the cylinder 9 on the closing side. The oil supply passage 15 is connected to an oil pump (not shown) through an oil hole (not shown) formed in the engine block 13, and hydraulic oil sent from the oil pump is introduced into the pressure chamber 14. It has come to introduce. At the end of the oil supply passage 15 on the pressure chamber 14 side, a check valve 16 that permits only the flow of hydraulic oil from the oil supply passage 15 side to the pressure chamber 14 side is provided.

  A minute leak gap 17 is formed between the sliding surfaces of the plunger 10 and the cylinder 9, and the hydraulic oil in the pressure chamber 14 flows out of the cylinder 9 through the leak gap 17. .

  A return spring 18 is incorporated in the pressure chamber 14. One end of the return spring 18 is supported by the check valve 16, and the other end presses the protruding end portion of the plunger 10 from the cylinder 9, and the pressing force biases the plunger 10 in the direction in which the plunger 10 protrudes from the cylinder 9.

  A ring accommodating groove 20 extending in the circumferential direction is formed in the inner periphery of the opening portion of the cylinder 9, and a register ring 21 is accommodated in the ring accommodating groove 20 so as to be movable in the axial direction.

  As shown in FIG. 3, the register ring 21 is formed by bending a single metal wire, and is provided at a ring part 22 having a shape in which a part of the circumference is cut off, and at both ends of the ring part 22. And a pair of operation pieces 23 and 24 for expanding the diameter of the ring portion 22. The pair of operation pieces 23 and 24 are formed so as to extend in a tangential direction from both ends of the ring portion 22 and cross, and the pair of operation pieces 23 and 24 are paired so that the distance between the tips of the operation pieces 23 and 24 is narrowed. By pinching the pieces 23 and 24, the ring portion 22 can be elastically expanded in diameter.

  As shown in FIG. 2, a plurality of circumferential grooves 25 adjacent in the axial direction are provided on the outer periphery of the plunger 10, and one of the circumferential grooves 25 is tightened by the ring portion 22 of the register ring 21. It has become. In each circumferential groove 25, a tapered surface 26 that rises toward the insertion end of the plunger 10 into the cylinder 9 and a stopper surface 27 that rises toward the protruding end of the plunger 10 from the cylinder 9 are provided. The tapered surface 26 rises gently, and when the load in the protruding direction is applied to the plunger 10, the diameter of the register ring 21 is increased to allow the movement of the plunger 10. On the other hand, the stopper surface 27 has a steep rise, and when the load in the pushing direction is applied to the plunger 10, the register ring 21 is locked to restrict the movement of the plunger 10.

  A tapered inner peripheral surface 28 rising to the closed end side of the cylinder 9 and an axis perpendicular end surface 29 rising to the opening end side of the cylinder 9 are formed in the ring housing groove 20. The taper inner peripheral surface 28 has a gentle rise, and receives the register ring 21 when the plunger 10 moves in the pushing direction, thereby limiting the diameter of the register ring 21. The axially perpendicular end surface 29 receives the register ring 21 when the plunger 10 moves in the protruding direction and restricts further movement of the register ring 21, but allows the diameter of the register ring 21 to be expanded in this state.

  The cylinder 9 has a notch 30 formed so as to cross the ring receiving groove 20 and penetrate the cylinder 9 in the radial direction. The pair of operation pieces 23 and 24 of the register ring 21 are exposed from the notch 30 of the cylinder 9 to the outside of the cylinder 9.

  As shown in FIG. 3, the notch 30 has a pair of facing surfaces 32 and 33 facing each other in a direction orthogonal to the seat surface 31 on the outer periphery of the cylinder 9. The seat surface 31 is a flat surface supported by the side surface of the engine block 13. Both ends of the ring receiving groove 20 are open to the opposing surfaces 32 and 33.

  The cylinder 9 has a pair of facing surfaces 32 and 33 inside the notch 30, and the outer surface of the facing surface 33 on the side close to the seating surface 31 on the outer periphery of the cylinder 9 extends from the radially outer end to the facing surface 32 on the opposite side. An operation piece support portion 34 that protrudes toward the surface is provided. The operation piece support part 34 contacts the tip of the operation piece 24 on the side close to the seating surface 31 on the outer periphery of the cylinder 9 among the pair of operation pieces 23 and 24 of the register ring 21 so as not to move in the circumferential direction of the cylinder 9. I support it.

  Of the pair of operation pieces 23 and 24 of the register ring 21, the operation piece 23 far from the outer peripheral seating surface 31 of the cylinder 9 has a length that penetrates the notch 30 and protrudes toward the outer diameter side of the cylinder 9. It is formed to have. The operation piece 23 includes a cross portion 23a extending in a tangential direction from an end portion of the ring portion 22 of the register ring 21, and a tool contact portion extending in a direction away from the cylinder 9 in parallel to the seat surface 31 from the tip of the cross portion 23a. 23b, and a knob 23c (see FIG. 4) extending in the axial direction of the cylinder 9 from the tip of the tool contact portion 23b. Here, the tool contact portion 23 b and the knob portion 23 c are provided so as to protrude from the notch 30 to the outer diameter side of the cylinder 9. Then, the tip of a rod-shaped tool 35 (see FIG. 5) is brought into contact with the tool abutting portion 23b, and the tool abutting portion 23b is pushed by the tool 35 from the side far from the seat surface 31 toward the near side. The diameter of the ring portion 22 can be increased.

  As shown in FIG. 3, a tool guide piece 36 is integrally formed on the outer periphery of the cylinder 9 so as to face the tool contact portion 23 b of the operation piece 23 of the register ring 21. Here, the tool guide piece 36 is disposed so as to face the operation piece 23 on the side far from the seat surface 31. Further, the tool guide piece 36 and the operation piece support portion 34 are arranged so as to face each other in a direction orthogonal to the seat surface 31.

  The tool guide piece 36 has a tool insertion hole 38 through which the tool 35 is inserted on the surface 37 of the operation piece 23 facing the tool contact portion 23b. The tool insertion hole 38 is a portion that slides and supports the side surface of the tool 35 when the tool abutting portion 23b of the operation piece 23 is pushed and moved by the tip of the tool 35 (see FIG. 5). The inner periphery of the tool insertion hole 38 has a tapered surface 39 that gradually expands from a side closer to the operation piece 23 toward a side farther from the operation piece 23, and an inner constant constant provided adjacent to the side of the taper surface 39 closer to the operation piece 23. And a straight surface 40.

  As shown in FIG. 4, the portion of the straight surface 40 of the tool insertion hole 38 is axially overlapped with the entire axial width W of the ring receiving groove 20 when viewed in a direction orthogonal to the outer peripheral seating surface 31 of the cylinder 9. It has a width D. That is, even when the register ring 21 is in any position in the axial direction inside the ring receiving groove 20, the tip of the tool 35 (see FIG. 5) inserted through the tool insertion hole 38 is used as the tool contact portion of the register ring 21. A tool insertion hole 38 is formed so as to have an axial width D that can be brought into contact with 23b.

  As shown in FIG. 5, a chain cover 41 facing the side surface of the engine block 13 is attached to the engine block 13 with the chain tensioner 1 in between. A service hole 42 for maintenance is formed in the chain cover 41. A female screw into which a service hole plug (not shown) is screwed is formed on the inner periphery of the service hole 42. Here, the service hole 42 of the engine cover, the tool insertion hole 38 of the tool guide piece 36, and the tool contact portion 23b of the register ring 21 are arranged in a straight line.

  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 14 through the leak gap 17, 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 18 and absorbs the slack of the chain 6. At this time, the check valve 16 is opened, and the hydraulic oil flows into the pressure chamber 14 from the oil supply passage 15, 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 21 moves back and forth within the ring receiving groove 20. Further, when the movement range in the protruding direction of the plunger 10 exceeds the movable range in the ring receiving groove 20 of the register ring 21 due to the slack of the chain 6, the tapered surface 26 in the circumferential groove 25 causes the register ring to move. The diameter of 21 is expanded to allow the plunger 10 to move. At this time, the register ring 21 engages with the adjacent circumferential groove 25.

  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 21 and the circumferential groove 25 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 the chain tensioner 1 is assembled for the first time or when the chain tensioner 1 is subsequently disassembled for overhaul, the pair of operation pieces 23, 24 are arranged so that the distance between the ends of the pair of operation pieces 23, 24 of the register ring 21 is reduced. The ring portion 22 is elastically expanded in diameter, and the plunger 10 is inserted into or extracted from the cylinder 9 in this state.

  By the way, when performing engine maintenance or the like, it is necessary to loosen the chain 6 temporarily. At this time, by expanding the diameter of the ring portion 22 of the register ring 21, the restriction on the movement of the plunger 10 by the no-back mechanism is released, and when the plunger 10 is pushed into the cylinder 9 in this state, the movement of the plunger 10 is performed. Accordingly, the chain 6 is loosened.

  In the operation of loosening the chain 6, the diameter expansion operation of the register ring 21 can be performed, for example, as follows. As shown in FIG. 5, the tool 35 is inserted into the chain cover 41 from the service hole 42 provided in the chain cover 41, and the tip of the tool 35 is inserted into the tool insertion hole 38 of the tool guide piece 36. At this time, since the tool 35 is positioned at the peripheral edge of the tool insertion hole 38, the tip of the tool 35 is easily aligned with the position of the operation piece 23. When the tip of the tool 35 is brought into contact with the tool contact portion 23b of the operation piece 23 and the operation piece 23 is pushed and moved by the tip of the tool 35, the diameter of the register ring 21 is increased. Here, when the operation piece 23 is pushed and moved by the tip of the tool 35, the side surface of the tool 35 is slidably supported by the peripheral portion of the tool insertion hole 38, so that the position of the tool 35 is stabilized and the tip of the tool 35 is It is easy to push and move the operation piece 23.

  Since the chain tensioner 1 has a tool guide piece 36 that slides and supports the side surface of the tool 35 on the outer periphery of the cylinder 9, when the operation piece 23 is pushed and moved by the tip of the tool 35, the tip of the tool 35 is moved to the operation piece 23. And the operation piece 23 is pushed and moved with the tip of the tool 35. Therefore, the operation of inserting the tool 35 into the chain cover 41 from the service hole 42 provided in the chain cover 41 and expanding the diameter of the ring portion 22 of the register ring 21 with the tool 35 is easy.

  The chain tensioner 1 also guards the periphery of the operation piece 23 with the tool guide piece 36 even when the operator searches for the position of the operation piece 23 of the register ring 21 with the tool 35 inserted into the service hole 42. Thus, the side surface of the tool 35 can be prevented from coming into contact with the operation piece 23. That is, as shown in FIG. 9, when the tool guide piece 36 does not exist on the outer periphery of the cylinder 9, when the operator searches for the position of the operation piece 23 of the register ring 21 with the tool 35 inserted into the service hole 42. In addition, the side surface of the tool 35 may come into contact with the operation piece 23 and the register ring 21 may be plastically deformed. On the other hand, the chain tensioner 1 of this embodiment is provided with a tool guide piece 36 on the outer periphery of the cylinder 9 as shown in FIG. When the operation piece 23 is searched for the position, the tool guide piece 36 guards the periphery of the operation piece 23. For this reason, it is possible to prevent the register ring 21 from being plastically deformed by the contact of the tool 35.

  In the chain tensioner 1, when the tip of the tool 35 is inserted into the tool insertion hole 38, the tip of the tool 35 is guided by the tapered surface 39 on the inner periphery of the tool insertion hole 38. Therefore, the operation of aligning the tip of the tool 35 with the position of the operation piece 23 is smooth.

  Further, in this chain tensioner 1, the tool insertion hole 38 has an axial width D that overlaps the entire axial width W of the ring receiving groove 20, so that the register ring 21 is in any position in the ring receiving groove 20. Even in this state, the operation piece 23 of the register ring 21 can be pushed and moved by the tip of the tool 35 inserted through the tool insertion hole 38.

  FIG. 6 shows a modification of the tool guide piece 36. The tool guide piece 36 is formed to extend from the outer periphery of the cylinder 9 in parallel with the tool contact portion 23 b of the operation piece 23. The tool guide piece 36 is disposed on the front side in the axial direction with respect to the axial width W of the ring receiving groove 20. When the operation piece 23 is pushed and moved by the tip of the tool 35 (see FIG. 5), the side surface of the tool 35 is slidably supported by the axial rear surface 43 of the tool guide piece 36. In this way, the tip of the tool 35 is easily aligned with the position of the operation piece 23, and the operation of moving the operation piece 23 with the tip of the tool 35 is easy.

  FIG. 7 shows another modification of the tool guide piece 36. The tool guide piece 36 includes a pair of opposed pieces 44 formed to extend from the outer periphery of the cylinder 9 in parallel with the tool contact portion 23 b of the operation piece 23. The pair of opposed pieces 44 are arranged so as to face the front and rear in the axial direction with the axial width W of the ring receiving groove 20 interposed therebetween. The facing surface 45 between the pair of facing pieces 44 has an axial width D that overlaps the entire axial width W of the ring receiving groove 20. When the operation piece 23 is pushed and moved by the tip of the tool 35 (see FIG. 5), the side surface of the tool 35 is slidably supported by the opposed surface 45 between the pair of opposed pieces 44. In this way, the tip of the tool 35 is easily aligned with the position of the operation piece 23, and the operation of moving the operation piece 23 with the tip of the tool 35 is easy.

  FIG. 8 shows still another modification of the tool guide piece 36. The tool guide piece 36 includes a root piece 46 extending from the outer periphery of the cylinder 9 in parallel with the tool contact portion 23b of the operation piece 23, and a tip piece 47 extending in the axial direction from the tip portion of the root piece 46. . The root piece 46 is disposed on the axially rear side of the axial width W of the ring receiving groove 20, and the tip piece 47 is disposed on the axially front side of the root piece 46. The tip piece 47 has an axial width D that overlaps the entire axial width W of the ring receiving groove 20. When the operation piece 23 is pushed and moved by the tip of the tool 35 (see FIG. 5), the side surface of the tool 35 is slidably supported by the axial front surface 48 of the root piece 46. In this way, the tip of the tool 35 is easily aligned with the position of the operation piece 23, and the operation of moving the operation piece 23 with the tip of the tool 35 is easy. Also, when the operator searches for the position of the operation piece 23 of the register ring 21 with the tool 35 inserted into the service hole 42, the periphery of the operation piece 23 is guarded by the tool guide piece 36, and the side surface of the tool 35 is Can be prevented from coming into contact with the operation piece 23.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Chain tensioner 9 Cylinder 10 Plunger 18 Return spring 20 Ring accommodation groove 21 Register ring 22 Ring part 23, 24 Operation piece 23b Tool contact part 25 Circumferential groove 26 Tapered surface 27 Stopper surface 30 Notch 36 Tool guide piece 37 Opposite surface 38 Tool insertion hole 39 Tapered surface W Axial width D Axial width

Claims (4)

A cylindrical cylinder (9) with one end open and the other end closed;
A plunger (10) inserted slidably in the axial direction into the cylinder (9);
A return spring (18) for biasing the plunger (10) in a direction protruding from the cylinder (9);
A plurality of axially adjacent circumferential grooves (25) provided on the outer periphery of the plunger (10);
A ring receiving groove (20) formed in the inner periphery of the cylinder (9);
A register ring (21) received in the ring receiving groove (20) and tightening the circumferential groove (25) on the outer periphery of the plunger (10);
The register ring (21) includes a ring part (22) having a shape in which a part of the circumference is cut off, and a pair of operation pieces for expanding the diameter of the ring part (22) provided at both ends of the ring part. (23, 24)
Each circumferential groove (25) expands the diameter of the ring portion (22) of the register ring (21) when a load is applied in a direction in which the plunger (10) protrudes from the cylinder (9). A tapered surface (26) that allows movement of the plunger (10) and a ring portion (22) of the register ring (21) when a load is applied in a direction in which the plunger (10) is pushed into the cylinder (9). And a stopper surface (27) that restricts movement of the plunger (10) by locking the
The cylinder (9) has a notch (30) that crosses the ring receiving groove (20) and penetrates the cylinder (9) in the radial direction, and from the notch (30) to the cylinder (9) In the chain tensioner in which the pair of operation pieces (23, 24) are exposed to the outside,
At least one of the pair of operation pieces (23, 24) has a length that penetrates the notch (30) and protrudes toward the outer diameter side of the cylinder (9), and the operation piece (23) The ring portion (22) can be expanded in diameter by pushing the projecting portion (23b) to the outer diameter side of the cylinder (9) with the tip of the rod-shaped tool (35).
A tool guide piece (36) that slides and supports the side surface of the tool (35) when the operation piece (23) is pushed and moved by the tip of the tool (35) is provided on the outer periphery of the cylinder (9). A featured chain tensioner. The tool guide piece (36) is provided so as to face a protruding portion (23b) of the operation piece (23) toward the outer diameter side of the cylinder (9),
The said tool guide piece (36) has the tool penetration hole (38) which penetrates the said tool (35) in the opposing surface (37) with respect to the protrusion part (23b) of the said operation piece (23). Chain tensioner.   The chain tensioner according to claim 2, wherein a taper surface (39) that gradually expands toward a side farther from a side closer to the operation piece (23) is provided on an inner periphery of the tool insertion hole (38).   The chain tensioner according to claim 2 or 3, wherein the tool insertion hole (38) has an axial width (D) that overlaps an entire axial width (W) of the ring receiving groove (20).

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