JP4532191B2 - Chain tensioner - Google Patents

Description

  The present invention relates to a structure for incorporating a register ring of a chain tensioner in which a register ring is incorporated in a chain tensioner used in a chain transmission device for driving a camshaft of a vehicle engine or the like.

  In a chain transmission device including a chain tensioner that drives a camshaft of a vehicle engine, the chain tensioner is adjusted to keep the chain tension constant. The chain tensioner has a spring and plunger built into the housing, and gives the plunger outward protrusion by the elastic force of the spring. The plunger is pressed into a tensioned state, and the pushing force from the chain is reduced. When acting on the plunger, it is buffered by the hydraulic pressure in the hydraulic damper chamber provided in the inner part of the plunger, and is provided so as to keep the tension constant even if the chain tension varies.

  In this way, the chain tensioner has a reduced damping characteristic that occurs when the engine is restarted after stopping the engine, eliminates inconveniences such as the generation of abnormal noise, downsizing in the axial direction, improved machining accuracy, operating conditions, and handleability, etc. There are various problems, and “Chain Tensioner” is disclosed in Patent Document 1 as a proposal for dealing with such problems. This chain tensioner has a plunger in the housing and a return spring inserted in the hollow portion of the plunger so as to give outward protrusion, and can be engaged with a plurality of grooves formed on the outer periphery of the plunger. Register ring, a check valve for preventing the backflow of the working fluid supplied into the housing, and a first stopper for restricting the backward movement of the plunger.

  The chain tensioner having the above configuration has a ring portion in the register ring and an operation portion for expanding the diameter of the ring portion, and the operation portion is operated from a notch provided in the housing portion so that the operation portion can be operated from the outside of the housing. It can be done. The operation portion is formed by intersecting the end portions of the register ring, and is provided in a non-contact manner with the cylinder. For this reason, various advantages such as smooth and easy switching of the operating state of the chain tensioner (initial setting, reverse movement restriction, disassembly restriction, etc.) and improved handling are obtained.

  The above-mentioned patent application (Japanese Patent Application No. 2003-333874) proposes a tensioner provided with the register ring as described above and provided with an initial set member until the engine is mounted on the chain tensioner in which the backward movement of the plunger is restricted. In this prior application, like the chain tensioner of Patent Document 1, a register ring is provided as a backward movement restricting means, and this chain tensioner is provided with an initial setting member until the engine is mounted. This initial setting member is a lock pin provided at the tip of the plunger and a support pin inserted into a pin hole formed at the tip of the housing, and the lock lever is supported by the support pin so as to be swingable. The plunger is held at the initial set position by the combination.

  By providing such an initial setting member, the plunger is always set in a state where the inner end of the plunger in the cylinder chamber is pushed to a predetermined initial position in the initial setting state until the engine is mounted. However, if the register ring is not correctly set due to incorrect assembly after assembly at the normal assembly position of the plunger outer peripheral groove in the initial set state, the initial set state will be released after it is installed on the engine and it will be in the operating state. If the return amount of the plunger is insufficient, the change in the chain running line cannot be followed, and the chain tension may increase. This is due to the following reason.

FIG. 5 is a cross-sectional view of a main part including a ring receiving groove 9 of a chain tensioner having a conventional register ring. FIG. 5A is a state in which the register ring 6 is assembled at a normal assembly position, and FIG. A state in which the register ring 6 is assembled at the assembly position is shown. As shown in (a) FIG, if the register ring 6 (shown as a ring 6a) is Rarere assemble the normal assembly position, relative to the initial setting state S _0, the plunger 2 in the initial unset state S ₁ is the return spring When the chain protrudes due to the reaction force and initially protrudes until the chain is tensioned, the initial protrusion amount P ₁ is obtained. In the initial set release state S ₂ , the plunger 2 moves in the axial direction in the ring receiving groove 9 when a pushing force is applied from the chain. The movable return amount P ₂ is movable.

In the initial set released state S ₁ , the movement of the register ring 6 in the axial direction is restricted by the plunger protruding side end surface of the ring receiving groove 9 when the plunger 2 is initially protruded. The plunger 2 moves according to the protruding amount of the plunger 2. Also, the initial unset state S ₂ the register ring when the plunger 2 is subjected to pushing force from the chain 6 is required to keep the tension with the plunger 2 back to the annular engaging groove 2c of the initial set position constant It engages with the lock surface of the ring receiving groove 9 set to a predetermined length.

On the other hand, as shown in FIG. 5B, the annular engagement groove on the back side from the position of the most protruding side end (initial setting position) of the plunger 2 to which the register ring 6 should originally be assembled in the initial setting state. If the assembly is misassembled, the initial set state S ₀ and the initial set release state S ₁ are the same and the initial protruding amount P ₁ is obtained, but in the initial set release state S ₂ , the possible return amount P _{2 is obtained.} 'Becomes the same as the initial protrusion amount P ₁ and becomes smaller than the possible return amount P ₂ that should be moved when the pushing force from the chain is applied, so the possible return amount is insufficient and cannot follow changes in the chain travel line. This will increase the chain tension.

In the initial setting state as described above, the cause of the register ring 6 being assembled in the groove closer to the back side of the plunger than the normal assembly groove (the groove at the initial position) of the plunger 2 is It is assumed that after assembling to the tensioner, some external force is applied to the operation portion (knob portion) for expanding the diameter of the register ring, and it is assembled after jumping one groove. As shown in FIG. 5B, there is no structural restriction between the annular engagement groove 2c of the plunger 2 and the ring receiving groove 9, so that the state shown in FIG. This is because it can occur for a reason.
JP 2001-355691 A

  In the chain tensioner of the type having a register ring between the plunger in the housing and the cylinder chamber, the present invention always keeps the register ring assembled in the initial set position at the time of assembling or after the assembly. It is an object of the present invention to provide a chain tensioner register ring built-in structure capable of securing the state.

As means for solving the above-mentioned problems, the present invention incorporates a plunger slidable in a cylinder chamber formed in a housing and a spring for pressing the plunger outward, and a plurality of locations on the outer peripheral surface of the plunger. The plunger between the housing and the plunger is sandwiched between the annular engaging groove having the locking surface provided at equal intervals and the ring receiving groove having the locking surface provided on the inner diameter surface of the housing, and the register ring incorporated in the outer peripheral surface of the plunger is sandwiched between In the chain tensioner provided with the backward movement restricting means that prevents the rearward movement of the cylinder toward the bottom surface of the cylinder chamber, the initial state in which the plunger is held in the initial set position with respect to the housing until the engine is assembled. the setting mechanism is provided, with being held at the initial set position by the initial setting mechanism, most of the plunger Annular engagement groove in the register ring Extension end close is set, the lines of gaps registering the locking surface and the locking surface of the ring receiving annular groove engagement groove adjacent to the most projecting end toward the annular engaging groove than it was with the chain tensioner Na characterized in that a register ring set means set smaller than the diameter.

  According to the chain tensioner of the present invention configured as described above, the register ring is always assembled at the correct initial position in the initial set state until it is attached to the engine, and this state is maintained. The action of the chain tensioner is the same as that of the conventional one. When the chain is set to a predetermined tension with a plunger that is given outward protrusion by a spring, and the pushing force acts on the plunger, the hydraulic pressure in the hydraulic damper chamber To adjust the chain tension to be constant. The plunger is held in a state of being pushed in advance to the initial setting position by the initial setting mechanism.

  The register ring is also inserted into the cylinder chamber in the housing before being set to the initial set state, and when the plunger is inserted, the predetermined position where the innermost end of the plunger is pushed in most is the initial position and the position closer to the protruding side of the plunger. It engages with the annular engagement groove. In this case, the register ring setting means restricts the clearance between the lock surface of the annular engagement groove and the lock surface of the ring receiving groove to a dimension equal to or smaller than the wire diameter of the register ring, and when the register ring is initially set, the ring engagement at the initial set position is performed. Since it is formed to engage with the mating groove, even if it is mistakenly assembled to the adjacent engaging groove, it cannot be inserted dimensionally, so the register ring must be in the initial position. It becomes. In addition, even if some force acts on the operation part of the register ring after assembly and the ring part tries to deviate from the initial position, if there is no force on the operation part, it will return to the original initial position, and this state is surely ensured. The

  The chain tensioner register ring built-in structure of the present invention includes a backward movement restricting means using a register ring with respect to a plunger inserted into the housing, an initial setting mechanism that is set at an initial position and holds the state, Since the register ring setting means for setting the register ring at the initial position is provided, the assembly is always performed at the initial position when the register ring held at the initial position by the initial setting mechanism is assembled in the housing. The effect that the state is ensured until the initial set state is released is obtained.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main cross-sectional view of the chain tensioner of the embodiment. The illustrated chain tensioner has basically the same configuration as that of Patent Document 1, but the detailed configuration in which the register ring is provided is different. Hereinafter, the same configuration will be briefly described in detail. As shown in the figure, the chain tensioner A has a plunger 2 slidably inserted into a cylinder chamber 1a formed in an open shape in the housing 1 and a return inserted in a hollow chamber 2a formed in the plunger 2. A spring 3 and a check valve 4 for preventing a backflow of hydraulic oil supplied from a tank (not shown) on an oil supply passage 5 communicating with the pressure chamber 1b are provided. 1 _A is a housing base for mounting to the engine block.

As shown in FIG. 2, the housing 1 is formed in a stepped shape with a small outer diameter near the opening end, and a register ring 6 is provided in a notch 7 formed in a part of the small diameter portion. An initial setting mechanism 8 for holding the plunger 2 in an initial setting state is provided between the head 2 _{H of the} plunger 2 and the opening end of the housing 1 until the chain tensioner A is attached to the engine block. Is provided. The register ring 6 and the initial setting mechanism 8 will be described in detail later.

The housing 1 is formed of a bottomed cylindrical body with one end closed and the other end open, and hydraulic oil supplied from a tank (not shown) installed below the housing 1 is supplied to the oil supply passage 5 at the housing end. The communication chamber 5 a communicates with the pressure chamber 1 b through a flow path 4 c formed in the valve seat 4 b of the check valve 4. The check valve 4 is provided to prevent the hydraulic oil from the pressure chamber 1b from flowing backward by closing a valve seat provided on the pressure chamber 1b side of the flow path 4c with the check ball 4a. 4 _R is a retainer for limiting the movement of the check ball, multiple notches therein.

One end of the return spring 3 inserted in the hollow chamber 2a of the plunger 2 is in contact with and supported by the valve seat 4b, and the other end is in contact with the inner end of the hollow chamber 2a so Protrusions are imparted. Further, as shown in the drawing, since the lower end of the hollow chamber 2a is open, the pressure chamber 1b formed between the end of the plunger 2 inserted into the cylinder chamber 1a and the valve seat 4b communicates with the hollow chamber 2a. As a whole, a hydraulic damper chamber _2D is formed. An annular safety groove 2b is formed on the outer peripheral portion of the plunger 2 slightly behind the center in the length direction. When the plunger 2 protrudes outward, the safety groove 2b is formed in an end wall 9c (stopper) of a ring receiving groove 9 provided with a register ring 6 that engages with the rear end of the groove 1a. This is provided to restrict the pop-up of the plunger 2 by this (disassembly restriction).

Further, a plurality of annular engagement grooves 2c (six in the illustrated example) provided at equal intervals in the axial direction are provided on the outer periphery closer to the protruding side from the center of the plunger. The annular engagement groove 2c has a serrated concave shape in a cross-sectional view. As shown in FIG. 4, the wall surfaces on both sides in the axial direction from the minimum diameter position are tapered, and the plunger The wall surface near the back is a gently inclined tapered surface 2c ₁ , and the lock surface 2c ₂ near the protruding end of the plunger has a larger inclination angle (engagement surface) than the taper surface 2c ₁ . The tapered surface and the lock surface are formed as smoothly continuous curved surfaces. Note that a cylindrical surface remains at a position adjacent to each annular engagement groove 2c.

As shown in FIGS. 2 and 3, the register ring 6 includes a C-shaped ring portion 6a and a shaft portion 6b and a tip portion 6c of an operation portion provided at both ends thereof, and the two shaft portions 6b and 6b are The two tips 6c and 6c are formed by crossing each other in the middle and bent near the outer periphery of the housing. In order to make the front ends 6c and 6c of the register ring 6 operable from the outside, a U-shaped notch 7 is formed in a part of the other end of the housing 1 as shown in FIG. As shown in FIG. 1, in the initial setting state in which the ring portion 6a is wound around the plunger 2, the shaft portion 6b and the tip 6c of the operation portion are accommodated in the notch 7, and the head _2H is slightly It is provided so as to protrude outward from the housing.

As shown in FIGS. 1 to 3, the initial setting mechanism 8 includes a lock pin 8 a provided in the plunger head 2 _H so as to protrude in the radial direction, and an axial extension 1 c at the step of different diameter of the housing 1. A support pin 8c provided in the extending portion 1c with a pin hole formed in a direction orthogonal to the axial direction, and a lock lever that is slidably engaged with the lock pin 8a by the support pin 8c. 8b, and the plunger 2 is pushed in by engagement of the lock lever 8b and the lock pin 8a so that the initial setting can be made. When the plunger 2 is set to the initial position by the initial setting mechanism 8, as shown in the cross section of FIG. The annular engagement groove 2c is set at a position closest to the plunger protruding end.

The ring receiving groove 9 includes a groove surface 9a having a depth sufficient to receive the ring portion 6a of the register ring 6, a lock surface (tapered surface) 9b having a gentle inclination on the back side thereof, and a portion closer to the protruding end of the plunger. And an end portion 9c. If the ring portion 6a is set at the initial position shown in the drawing (the position of the annular engagement groove 2c closest to the protruding end of the plunger) as shown in FIG. locking surface (wall) 2c ₂ and register ring set means so that a gap d is the wire diameter is smaller than value of the ring portion 6a of the inclined direction of the engagement groove 2c is formed. In this case, it is assumed that the plunger 2 is pushed in until the ring portion 6a reaches the initial setting position.

  Note that the operation portions (6b, 6c) of the register ring 6 have such a length that the bending direction of the tip 6c is directed toward the protruding end of the plunger 2, and each of the tips 6c, 6c protrudes slightly from the other end of the housing 1. Is set to If the register ring 6 is inserted into the ring receiving groove 9 in the direction opposite to the direction shown in FIG. 2, the register ring 6 is slightly inclined with respect to the central axis of the cylinder chamber 1a and is inserted in the opposite direction. The lengths of the tips 6c and 6c are set to the lengths of recognizing this. Further, the position of the back wall 7a of the notch 7 is also set in consideration of the length of the tips 6c and 6c within the range of the required moving stroke of the register ring 6.

In the chain tensioner of the embodiment having the above-described configuration, the basic operation is the same as that of the conventional one, but misassembly of the register ring is prevented. The plunger 2 is provided with an outward projecting property by the elastic force of the return spring 3, presses the chain with the head 2 _H of the plunger 2 to be in a tension state, and when the pushing force from the chain acts on the plunger, the hydraulic damper It is buffered by the hydraulic pressure in the chamber _2D , and acts to keep the tension constant even if the chain tension varies.

  Before the plunger 2 is pushed into the housing 1, the ring 6 a is inserted into the ring receiving groove 9 in advance using the notch 7, and the plunger 2 is pushed into the register ring 6 and assembled. Is done. At this time, since the register ring setting means is formed between the annular engagement groove 2c of the plunger 2 and the ring receiving groove 9 as described above, the ring portion 6a extends from the projecting side end beyond the gap d. It cannot enter into the annular engagement groove 2c of the eye, and is always in the normal position shown in FIG. 1 in the initial set state, thereby preventing the occurrence of an erroneous assembly state or a state where it moves to a different position thereafter.

  Even if the initial setting state is erroneously determined in the state where the plunger 2 is pushed only to the position of the second annular engagement groove 2c from the projecting side end, in that state, the lock pin 8a of the initial setting mechanism 8 is Since it cannot be engaged with the lock lever 8b, it will be noticed that the pushing position of the plunger 2 is wrong because the initial setting cannot be made. After the chain tensioner of this embodiment is attached to the engine, the lock lever 8b of the initial setting mechanism 8 is removed from the lock pin 8a as shown by a two-dot chain line in FIG.

  In the above embodiment, FIG. 2 and FIG. 3 show an example in which the register ring 6 is provided in a direction orthogonal to the initial setting mechanism 8 provided at the lower position of the plunger 2, but the register ring 6 is provided. The direction is not limited to the illustrated example, and the direction can be provided at any position as long as it does not interfere with the initial setting mechanism 8.

  In the above embodiment, the initial setting mechanism 8 includes the lock pin 8a, the lock lever 8b, and the support pin 8c. However, the housing 1 and the plunger 2 can be fixed at predetermined positions and can be released after the engine is mounted. Any structure can be employed.

  The chain tensioner register ring built-in structure of the present invention is constructed so that the register ring of the chain tensioner is accurately assembled at the initial position and the position thereof does not change, and is widely used for chain tensioners having a register ring. The

Main sectional view of the chain tensioner of the embodiment Partial side view Side view from arrow III-III in Fig. 2 Cross section of register ring set means Explanatory drawing of register ring assembly in conventional chain tensioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 1a Cylinder chamber 1b Pressure chamber 2 Plunger 2a Hollow chamber 2c Annular engagement groove 2c ₁ Tapered surface 2c ₂ Lock surface 2 _D Hydraulic damper chamber 3 Return spring 4 Check valve 4a Check ball 5 Oil supply passage 6 Register ring 6a Ring part 7 Notch 8 Initial setting mechanism 8a Lock pin 8b Lock lever 9 Ring receiving groove 9b Lock surface 9c End

Claims (2)

An annular engagement that incorporates a plunger that is slidable in a cylinder chamber formed in the housing and a spring that presses the plunger outward, and has locking surfaces provided at equal intervals on the outer peripheral surface of the plunger. The register ring built in the outer peripheral surface of the plunger is sandwiched between the groove and the ring receiving groove having the lock surface provided on the inner surface of the housing, and the plunger moves backward by a predetermined amount toward the bottom surface of the cylinder chamber between the housing and the plunger. in the chain tensioner provided with a retraction restricting means for preventing, until the engine assembling provided an initial setting mechanism for holding the plunger in the depressed state to the initial set position with respect to the housing, in the initial set position by the initial setting mechanism In the held state, set the register ring in the annular engagement groove closest to the protruding end of the plunger. It is, provided the register ring set means is set smaller than the wire diameter of the gaps registering the locking surface and the locking surface of the ring receiving annular groove engagement groove adjacent to the most projecting end toward the annular engaging groove chain tensioner Na, characterized in that. The annular engagement groove has a serrated concave shape in a cross-sectional view , and both wall surfaces in the axial direction from the position of the smallest diameter are gently inclined tapered surfaces on the back side of the plunger, and a lock surface having a large inclination angle on the plunger protruding side, forming as smooth continuous curved surface, the chain tensioner na according to claim 1, characterized in that ring-receiving groove has a tapered locking surface on the plunger back side.

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