JP2006214519A - Hydraulic chain tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To release initial set of a plunger from outside of a cylinder. <P>SOLUTION: The plunger 16 is inserted into a large diameter hole part 15a of a stepped through hole 15 formed in a housing 11. A resister ring 20 inside a ring storing groove 19 formed on the inner periphery of an opening end part of the large diameter hole part 15a keeps the plunger 16 in the initial set state by fastening the outer periphery of a tip part of the plunger 16. By inserting the housing 11 holding the plunger 16 into a tensioner mounting hole 2 formed on the cylinder 1, the housing 11 is fixed to the cylinder 1. The initial set of the plunger 16 is released, by inserting a plug body 24 on which a return spring 18 and a check valve 35 are mounted from outside of the cylinder 1 into the through hole 15, screwing a male screw 25 on the outer periphery of the plug body 24 into a female screw 26 formed on the inner periphery of a small diameter hole part 15b, and pressing the plunger 16 by the return spring 18. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic chain tensioner that keeps the tension of a chain for driving a camshaft constant.

  In general, in a chain transmission that transmits the rotation of the crankshaft to the camshaft, a chain tensioner is provided on the slack side of the chain, and the chain tension is applied to the chain to keep the chain tension constant. .

  As the chain tensioner, those described in Patent Document 1 and Patent Document 2 are conventionally known. The chain tensioners described in Patent Documents 1 and 2 are particularly used for motorcycles. In a motorcycle engine, because the air cooling fin is provided in the cylinder for air cooling, the chain of the timing chain system that drives the camshaft is arranged in the center of the cylinder, unlike the automobile engine. There are many cases. Therefore, the chain tensioner is also arranged at the center of the cylinder.

  For this reason, after the chain tensioner is mounted, a method of releasing the initial set of the chain tensioner from the outside of the cylinder is used.

  Here, in the chain tensioner described in Patent Document 1, a plunger and a return spring are incorporated in the plunger chamber of the tensioner body, and a bolt insertion hole having a diameter smaller than the inner diameter of the return spring is provided at the closed end of the plunger chamber. A spring receiver is provided at one end of the bolt inserted into the return spring from the insertion hole to press the return spring between the plunger closed end and the spring receiver is returned to the other end of the bolt located outside from the bolt insertion hole. A spring support lock member that displaces the spring between the compressed state and the open state is attached, the spring support is opened by operating the spring support lock member, and the plunger is pressed by the return spring to give outward protrusion. The chain tensioner is in the set state.

On the other hand, in the chain tensioner described in the conventional example of Patent Document 2, after the tensioner body in which the push rod is slidably assembled is bolted to the cylinder, a return spring is assembled from the rear part of the tensioner body, The return spring is contracted by attaching a cap that is screw-engaged with the tensioner body, thereby imparting outward pushability to the push rod.
Japanese Utility Model Publication No. 58-6034 Utility Model Registration No. 2569258

  Incidentally, since the chain tensioners described in Patent Document 1 and Patent Document 2 are both mechanical chain tensioners, the initial set of the plunger can be released after being attached to the cylinder. In the case of a chain tensioner, since the check valve is built into the pressure chamber formed on the back of the plunger, it is difficult to hold a return spring that imparts outward protrusion to the plunger. A hydraulic chain tensioner that can be released from the outside of the cylinder has not been proposed yet.

  An object of the present invention is to provide a small and compact hydraulic chain tensioner that can easily release an initial set of plungers from the outside of a cylinder.

  In order to solve the above problems, in the present invention, a housing having a mounting flange and having a through hole formed from the front end to the rear end, and a slidably inserted into the front end of the through hole. A plunger, a return spring for imparting outward protrusion to the plunger, and a ring receiving groove formed on the inner periphery of the end opening end of the through hole to elastically hold the plunger, and the plunger A resist ring that can be elastically deformed in the radial direction to release the holding of the plunger when a pressing force is applied to the return spring, and a reaction force of the return spring supported by being screwed in from the rear opening end of the through hole The housing is formed with an oil passage hole from the outer periphery to the inner periphery of the rear end, and the stopper body is supplied with hydraulic oil supplied to the oil passage hole. An oil supply passage is provided to flow out from the oil outlet that opens to the pressure chamber provided at the back of the plunger, and a check valve is provided at the oil outlet of the oil supply passage to prevent the hydraulic oil in the pressure chamber from flowing to the oil supply passage side. The configuration was adopted.

  Here, a plurality of engaging grooves extending circumferentially on the outer periphery of the plunger are provided at equal intervals in the axial direction, and the register ring is moved to the inner periphery of each engaging groove when the plunger is moved outward by pressing a return spring. By providing a taper surface for expanding the diameter and an engagement surface that engages the register ring when the plunger is pushed in, the rear wall surface of the ring receiving groove is a stopper surface that prevents the register ring from retreating, When the engine is stopped, if the pushing force is applied to the plunger due to the cam stop position, the register ring comes into contact with the stopper surface on the rear side of the ring receiving groove and stops. The plunger only retracts to the position where the two engage with each other, and the plunger can be prevented from largely retracting. For this reason, it is possible to prevent the chain from being greatly loosened when the engine is restarted.

  The check valve includes a spherical valve body that opens and closes the oil outlet of the oil supply passage, and a retainer that restricts the opening and closing amount of the valve body, and the retainer includes a cylindrical portion that can be press-fitted inside the end of the return spring. The cylindrical portion of the retainer has a cylindrical portion of the retainer, and the end portion of the return spring is connected to the cylindrical portion of the retainer by adopting a structure in which the cylindrical portion is press-fitted into the outer periphery of the circular protrusion formed on the distal end surface of the plug body The plug body and the return spring can be held in the assembled state by press-fitting. For this reason, the plug body and the return spring can be incorporated into the housing at the same time, and the chain tensioner can be easily assembled.

  Further, when a retaining groove for preventing the plunger from coming off by engagement of the register ring is provided at a position offset from the plurality of engaging grooves arranged in the axial direction to the plunger toward the rear end side of the plunger, the chain or the chain tensioner is removed. When the return spring is pressed, the plunger moves outward, and when the plunger moves to a position where the retaining groove faces the register ring, the register ring engages with the side surface of the retaining groove on the rear end side of the plunger. The plunger can be prevented from coming off by the combination. For this reason, the plunger and the return spring are not disassembled, and the chain tensioner can be easily reassembled.

  As described above, the oil supply passage is formed in the plug body that is screwed into the rear end portion of the through hole and closes the rear end opening of the through hole, and the check valve is provided at the oil outlet of the oil supply passage, thereby allowing the through hole to pass. Insert the plunger into the tip of the hole, attach the housing to the cylinder with the register ring elastically holding the plunger, insert the return spring into the through hole from the rear end of the housing, and insert the plug and screw it in. As a result, the plunger is moved outward by pressing the return spring to be in a set state, so that the initial setting of the plunger can be easily released from the outside of the cylinder.

  Further, by providing the check valve in the oil supply passage formed in the stopper, a smaller and more compact hydraulic chain tensioner can be obtained as compared with the case where the check valve is provided in the oil passage hole of the housing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a tensioner mounting hole 2 is formed in a cylinder 1 of the engine, and a chain tensioner 10 that presses a swingable chain guide 3 is incorporated in the tensioner mounting hole 2.

  Here, the chain guide 3 comes into contact with a chain (not shown) and presses the chain by a pressing force applied from the chain tensioner 10.

  The chain tensioner 10 has a housing 11 that is inserted into the tensioner mounting hole 2 from the outside of the cylinder 1. A ring groove 12 is formed on the outer periphery of the housing 11, and an O-ring 13 attached to the ring groove 12 serves as a housing. 11 and the fitting surface of the tensioner mounting hole 2 are sealed.

  The housing 11 has a mounting flange 14 on the outer periphery of the rear end portion. The flange 14 is abutted with the outer periphery of the cylinder 1 and is fixed to the cylinder 1 by tightening a bolt (not shown) screwed into the cylinder 1. The

  The housing 11 has a stepped through hole 15 extending from the front end to the rear end, and a plunger 16 is slidably inserted into a large-diameter hole portion 15 a located on the front end side of the through hole 15.

  The plunger 16 has a hollow portion 17 that opens at the rear end surface, and a return spring 18 inserted into the hollow portion 17 imparts outward protrusion to the plunger 16.

  A ring housing groove 19 is formed on the inner periphery of the open end of the large-diameter hole portion 15 a, and the register ring 20 is housed in the ring housing groove 19.

  As shown in FIG. 2, the register ring 20 has a ring portion 20 a and an operation portion 20 b for expanding the diameter of the ring portion 20 a, and the operation portion 20 b is a notch provided at the distal end portion of the housing 11. It faces the outside from 21.

  As shown in FIG. 1, a plurality of engagement grooves 22 are provided on the outer periphery of the plunger 16 at equal intervals in the axial direction. A retaining groove 23 is formed at a position offset from the plurality of engaging grooves 22 toward the rear end side of the plunger.

  As shown in FIGS. 3 (I) and (II), the inner periphery of each of the plurality of engagement grooves 22 is continuous with a tapered surface 22a having a small diameter end on the distal end side of the plunger and a small diameter end of the tapered surface 22a. An engagement surface 22b is formed, and the tapered surface 22a expands the diameter of the ring portion 20a of the register ring 20 when the plunger 16 is moved by pressing the return spring 18.

  When the engine is stopped, the engaging surface 22b is engaged with the ring portion 20a of the register ring 20 when a pushing force is applied to the plunger 16, and the ring portion 20a is engaged with the stopper surface 19a on the rear side of the ring receiving groove 19. By doing so, the backward movement of the plunger 16 is prevented.

  As shown in FIG. 1, a round shaft-shaped plug body 24 that closes the small-diameter hole portion 15 b is attached in the small-diameter hole portion 15 b of the through hole 15. The plug 24 has a male screw 25 on the outer periphery of the rear end portion, and the male screw 25 is engaged with a female screw 26 formed on the inner periphery of the rear end portion of the small diameter hole portion 15b. In addition, a seat plate 27 that abuts on the flange 14 of the housing 11 is provided at the rear end of the plug 24, and a square head 28 is formed on the seat plate 27.

  The housing 11 is provided with a ring groove 30 communicating with an oil passage 29 formed in the cylinder 1 and an oil passage hole 31 communicating with the ring groove 30 and extending in the radial direction. On the other hand, the plug body 24 is provided with an annular groove 32 communicating with the oil passage hole 31 and an oil supply passage 33 communicating with the annular groove 32. The oil outlet 33a of the oil supply passage 33 opens at the distal end surface of the plug 24, and hydraulic oil is sent from the oil outlet 33a to the pressure chamber 34 formed in the back portion of the plunger 16.

  A check valve 35 is provided at the oil outlet 33 a of the oil supply passage 33 to prevent the hydraulic oil in the pressure chamber 34 from flowing back into the oil supply passage 33. The check valve 35 includes a spherical valve body 36 that opens and closes the oil outlet 33a, and a retainer 37 that regulates the opening and closing amount of the valve body 36. The retainer 37 has a cylindrical portion 37a, and the cylindrical portion 37a is a stopper. It is press-fitted into a circular protrusion 38 formed on the distal end surface of the body 24 and coupled to the plug body 24.

  Here, the cylindrical portion 37a of the retainer 37 has an outer diameter capable of being press-fitted into the end portion of the return spring 18, and the plug body 24 and the return spring 18 are assembled by press-fitting the cylindrical portion 37a into the return spring 18. To be able to hold on.

  The chain tensioner 10 shown in the embodiment has the above structure, and when the engine is driven, the hydraulic oil is sent to the oil passage 29 by the operation of a hydraulic pump (not shown). The hydraulic oil flows from the ring groove 30 formed in the housing 11 to the oil passage hole 31, flows from the annular groove 32 formed in the plug body 24 to the oil supply passage 33, and flows into the pressure chamber 34 from the oil outlet 33a.

  For this reason, when the tension of the chain (not shown) increases and a pushing force is applied from the chain to the plunger 16 via the chain guide 3, the pushing force is buffered by the hydraulic oil sealed in the pressure chamber 34. The

  On the other hand, when slack occurs in the chain, the plunger 16 moves outward by the pressing of the return spring 18, and the slack of the chain is absorbed by the plunger 16 pressing the chain guide 3.

  At this time, since the check valve 35 opens the oil outlet 33a of the oil supply passage 33, the hydraulic oil is supplied from the oil supply passage 33 into the pressure chamber 34, and the plunger 16 moves rapidly in the outward direction to immediately remove the slack of the chain. Absorb.

  Further, when the plunger 16 moves outward, the taper surface 22a of the engagement groove 22 presses the ring portion 20a of the register ring 20, so the diameter of the ring portion 20a increases, and the plunger 16 moves outward. There is no hindrance.

  When the amount of movement of the plunger 16 in the outward direction becomes larger than the formation pitch of the engagement grooves 22, the next engagement groove 22 faces the ring portion 20a, and the tapered surface 22a is tightened by the ring portion 20a.

  When the engine is stopped and a pushing force is applied to the plunger 16 through the chain guide 3 due to the cam stop position, the plunger 16 moves backward, and as shown in FIG. 3 (II), the ring portion of the register ring 20 While 20a engages with the engaging surface 22b of the plunger 16, the ring part 20a engages with the stopper surface 19a on the rear side of the ring receiving groove 19, and the plunger 16 stops.

  For this reason, the plunger 16 does not retreat greatly, and even if the engine is restarted, the chain does not loosen greatly.

  When the chain is removed due to maintenance around the engine or the chain tensioner 10 is removed from the cylinder 1, the plunger 16 moves outward by pressing the return spring 18, and the ring portion 20a of the register ring 20 is shown in FIG. As shown in (III), the ring receiving groove 19 comes into contact with the front wall surface 19b and stops, and the rear wall surface 23a of the retaining groove 23 formed on the outer periphery of the plunger 16 comes into contact with the ring portion 20a. The plunger 16 is prevented from coming off by contact. For this reason, the plunger 16 and the return spring 18 do not fall off.

  In the state where the plunger 16 is prevented from falling off as described above, after removing the plug 24 and the return spring 18 from the housing 11, the operation part 20 b of the register ring 20 is picked and the plunger 16 is moved in a state where the diameter of the ring part 20 a is expanded. By pushing, the hydraulic chain tensioner 10 can be returned to the set state.

  When the hydraulic chain tensioner 10 is assembled to the cylinder 1, the plunger 16 is inserted into the large-diameter hole portion 15 a of the through hole 15 formed in the housing 11, the plunger 16 is pushed in, and the ring portion 20 a of the register ring 20. Holds the housing 11 and the plunger 16 in an assembled state by an elastic holding action that tightens the outer periphery of the tip of the plunger 16.

  The assembly is inserted into the tensioner mounting hole 2 from the outside of the cylinder 1, and the flange 14 of the housing 11 is brought into contact with the outer periphery of the cylinder 1 as shown in FIG. The flange 14 is fixed.

  After the housing 11 is fixed, the return spring 18 and the plug 24 are inserted into the inside from the open end of the small diameter hole 15b, and the male screw 25 of the plug 24 is screwed into the female screw 26 formed on the inner periphery of the small diameter hole 15b. The plug 24 is tightened until the seat plate 27 comes into contact with the flange 14 of the housing 11.

  The return spring 18 presses the plunger 16 by tightening the plug 24, and the plunger 16 moves outward by the pressing, so that the initial setting is automatically released and a set state as shown in FIG. 1 is obtained. .

  In this way, the initial setting of the plunger 16 can be easily released by inserting and tightening the plug 24 after incorporating the return spring 18 into the small-diameter hole 15b from the outside of the cylinder 1.

  Further, by providing the check valve 35 at the oil outlet 33a of the oil supply passage 33 formed in the plug body 24, the following effects can be obtained.

  That is, the check valve 35 that prevents the hydraulic oil in the pressure chamber 34 from flowing back into the oil supply passage 33 may be incorporated in the oil passage hole 31, but in this case, the outer diameter of the housing 11 becomes large, and the chain The tensioner becomes larger.

  However, by providing the check valve 35 at the oil outlet 33a of the oil supply passage 33, it is possible to prevent the housing 11 from becoming large, and it is possible to obtain a small and compact chain tensioner that is not restricted by mounting. .

  In the embodiment, a stepped hole is shown as the through hole 15, but a straight hole having the same diameter over the entire length may be used, or a stepped hole having a large diameter on the rear end side may be used.

Vertical front view showing a set state of the hydraulic chain tensioner according to the present invention Sectional view along the line II-II in FIG. (I) is an enlarged cross-sectional view of the register ring portion of FIG. 1, (II) is a cross-sectional view of a state in which the plunger is restrained from retreating, and (III) is a cross-sectional view of a plunger retaining state. Sectional drawing which shows the state in the middle of the assembly | attachment of the hydraulic chain tensioner of FIG.

Explanation of symbols

11 Housing 14 Flange 15 Through-hole 15a Large-diameter hole 15b Small-diameter hole 16 Plunger 18 Return spring 19 Ring receiving groove 19a Stopper surface 20 Register ring 22 Engaging groove 22a Taper surface 22b Engaging surface 23 Retaining groove 24 Plug body 31 Oil passage hole 33 Oil supply passage 33a Oil outlet 34 Pressure chamber 35 Check valve 36 Valve body 37 Retainer 37a Cylindrical part 38 Projection part

Claims (4)

  A housing having a mounting flange and having a through hole formed from the front end to the rear end, a plunger slidably inserted into the front end portion of the through hole, and imparting outward protrusion to the plunger The return spring and the plunger are elastically held in a ring receiving groove formed on the inner periphery of the end opening end of the through hole, and the plunger is held when the return spring is loaded with the return spring. A register ring that can be elastically deformed in a radial direction to release the plug, and a plug body that is screwed in from the rear opening end of the through hole to support the reaction force of the return spring. An oil passage hole extending to the inner periphery of the end is formed, and the plug body is provided on the back of the plunger from an oil outlet that opens the hydraulic oil supplied to the oil passage hole at the front end surface of the stopper body. Provided an oil supply passage to flow out into the pressure chamber, the hydraulic chain tensioner hydraulic oil in the pressure chamber to the oil outlet of the oil supply passage is provided with a check valve to prevent the flow into the oil supply passage side.   A plurality of circumferentially extending engaging grooves are provided on the outer periphery of the plunger at equal intervals in the axial direction, and the diameter of the register ring is increased when the plunger is moved outward by pressing a return spring on the inner periphery of each engaging groove. The tapered surface and an engagement surface that engages with the register ring when the plunger is pushed in are provided, and the rear wall surface of the ring receiving groove is a stopper surface that prevents the register ring from retreating. Hydraulic chain tensioner.   The check valve includes a spherical valve body that opens and closes the oil outlet of the oil supply passage, and a retainer that restricts the opening and closing amount of the valve body, and the retainer has a cylindrical portion that can be press-fitted inside the end of the return spring. The hydraulic chain tensioner according to claim 1 or 2, wherein the cylindrical portion is configured to be press-fitted into an outer periphery of a circular projecting portion formed on a distal end surface of the plug body and coupled to the plug body.   The chain tensioner according to claim 2 or 3, wherein the plunger is provided with a retaining groove for retaining the plunger by engagement of the register ring at a position offset from a plurality of engaging grooves arranged in the axial direction toward the rear end side of the plunger. .

Images