JP2020008040A - Chain tensioner - Google Patents

Abstract

To realize a simple retainer attachment structure which enables a valve opening pressure of a relief valve of a chain tensioner to be stabilized and eliminate a need of processing of a drain oil passage to a cylinder.SOLUTION: A cylinder 9 has a stepped hole part 26 into which a relief valve 18 may be inserted from the outside of the cylinder 9. A retainer 19 is formed by a toothed washer having: an annular part 29 forming a hollow hole 28; and an outer tooth part 30 pushed into the stepped hole part 26. The retainer 19 is attached to the stepped hole part 26 by engagement between the outer tooth part 30 and the stepped hole part 26. A storage space 33 in a valve sleeve 23 communicates with the outside of the cylinder 9 through the hollow hole 28 of the retainer 19.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chain tensioner for maintaining a constant tension of a camshaft driving chain of an engine or the like, and more particularly, to a chain tensioner having a structure in which fluctuations in the tension of the chain are absorbed by a hydraulic damper.

  2. Description of the Related Art In general, an automobile engine transmits the rotation of a crankshaft to a camshaft via a timing chain (hereinafter, referred to as a “chain”), and opens and closes a valve of a combustion chamber by the rotation of the camshaft. In order to maintain the tension of the chain in an appropriate range, a tension adjusting device including a chain guide provided so as to be swingable about a fulcrum shaft and a chain tensioner for pressing the chain via the chain guide is used.

  As a chain tensioner provided in the tension adjusting device, a cylindrical cylinder having one end opened and the other end closed, a plunger slidably inserted into the cylinder, and a biasing force for projecting the plunger from the cylinder. A check that includes a return spring, a pressure chamber formed in the cylinder behind the plunger, and an oil supply passage for introducing hydraulic oil into the pressure chamber, and allows only the flow of hydraulic oil from the oil supply passage to the pressure chamber side. A hydraulic valve in which a valve is disposed at an end of a fuel supply passage on the pressure chamber side is known (for example, Patent Documents 1 and 2).

  In the case of this type of hydraulic chain tensioner, if the tension of the chain increases during operation of the engine, the tension of the chain causes the plunger to move in the direction of being pushed into the cylinder (hereinafter referred to as the "pushing direction"). Absorb the tension. At this time, the hydraulic oil in the pressure chamber flows out of the pressure chamber through the leak gap between the plunger and the sliding surface of the cylinder, and a damper action is generated by viscous resistance of the hydraulic oil, so that the plunger moves slowly. . Here, when the pressure in the pressure chamber becomes higher than the pressure in the oil supply passage, the check valve closes and the pressure chamber is closed, so that the damper action is ensured. On the other hand, when the tension of the chain decreases during operation of the engine, the biasing force of the return spring causes the plunger to move in a direction in which the plunger protrudes from the cylinder (hereinafter, referred to as a “projection direction”), and absorbs slack in the chain. At this time, the check valve is opened, and the operating oil flows into the pressure chamber from the oil supply passage, so that the plunger moves quickly.

  Further, in the chain tensioners of Patent Documents 1 and 2, when the tension of the chain is suddenly increased, the pressure in the pressure chamber becomes larger than a preset pressure in order to prevent the chain from being over-tensioned. A relief valve for releasing the pressure in the pressure chamber is employed.

  Specifically, the relief valve has a valve element, a valve spring that biases the valve element in the valve closing direction, and a valve sleeve that forms a housing space for the valve element and the valve spring. It has a valve seat that forms a corresponding valve hole in the body. The cylinder has a stepped hole through which a relief valve can be inserted from outside the cylinder, and an oil drain that branches off from the large diameter hole of the stepped hole. A hollow hole is formed in the valve sleeve so as to penetrate between the inner circumference and the outer circumference of the valve sleeve. The hollow hole communicates with the housing space of the valve sleeve and the oil drain. A retainer for fixing the relief valve to the cylinder is attached to the stepped hole. The retainer is composed of a male screw member that can be screwed into a female screw formed in the stepped hole. The valve spring contacts the valve body and contacts the valve sleeve or the retainer on the side opposite to the valve body.

  When the pressure in the pressure chamber becomes larger than a preset pressure, the valve body of the relief valve separates from the seat surface of the valve seat portion to open a valve hole by the pressure, and the operating oil escapes to the accommodation space of the valve sleeve. The hydraulic oil that has escaped into the housing space flows through the hollow hole of the valve sleeve to the oil drain. When the pressure in the pressure chamber becomes lower than the preset pressure, the valve body of the relief valve is seated on the seat surface by the urging force of the valve spring to close the valve hole.

JP 2011-149466 A JP 2007-218371 A

  However, in the chain tensioners of Patent Documents 1 and 2, as a method of fixing the relief valve, a structure in which the relief valve is fixed by a stepped hole and a retainer screwed into the stepped hole is adopted. In this case, a compression load is applied to the relief valve due to the tightening axial force accompanying the screwing of the retainer, and the relief valve contracts in the axial direction.

  In the case of a screw-type retainer, female threading is performed on the stepped hole, and work for applying a loosening agent in advance and screwing the retainer are troublesome.

  In addition, it is necessary to machine the oil drain passage branched from the stepped hole in the cylinder, which increases the machining cost.

  The problem to be solved by the present invention is to realize a simple retainer mounting structure in which the valve opening pressure of the relief valve of the chain tensioner is stabilized, and to obviate the need for machining an oil discharge passage to the cylinder.

  In order to achieve the above object, the present invention provides a cylinder, a plunger slidably inserted into the cylinder, a return spring for urging the plunger in a direction protruding from the cylinder, A pressure chamber formed behind the plunger, an oil supply passage for introducing hydraulic oil into the pressure chamber, and when the pressure in the pressure chamber becomes larger than a preset pressure, the hydraulic oil is supplied to the pressure chamber. A relief valve for releasing the valve from the pressure chamber to the outside of the pressure chamber, and a retainer for fixing the relief valve to the cylinder, wherein the relief valve includes a valve element, a valve spring for urging the valve element in a valve closing direction, and the valve. A valve sleeve for housing the body and the valve spring, the valve sleeve forming a corresponding valve hole in the valve body. A chain tensioner having a groove seat portion, wherein the cylinder has a stepped hole through which the relief valve can be inserted from outside the cylinder, wherein the retainer is pushed into the annular portion forming a hollow hole and the stepped hole. And a retainer attached to the stepped hole by engagement of the external tooth and the stepped hole, and a housing space in the valve sleeve. However, a configuration that communicates with the outside of the cylinder through the hollow hole is adopted.

  According to the above configuration, the external tooth portion pushed into the stepped hole and the stepped hole are engaged by press-fitting the retainer made of the toothed washer into the stepped hole, and the retainer is engaged by the engagement. Can be attached to the stepped hole to fix the relief valve to the cylinder. Further, in the case of the retainer mounting structure by press fitting, the female thread is not required in the stepped hole, and there is no application of a loosening agent or a screwdriver, so that the retainer can be easily attached to the stepped hole. . In the press-fitting, it is possible to prevent an excessive force from being applied to the relief valve from the retainer, so that the valve opening pressure of the relief valve is stabilized. When a retainer made of a toothed washer is used, the housing space in the valve sleeve and the outside of the cylinder communicate with each other through the hollow hole of the retainer, and hydraulic oil can be discharged to the outside of the cylinder through the communication path. is there. For this reason, the cylinder does not need to be processed to form a drainage passage branched from the stepped hole.

  For example, it is preferable that the valve spring is formed of a coil spring, the valve spring is directly supported by the annular portion of the retainer, and the annular portion has a support protrusion that receives an inner circumference of the valve spring. In this case, the spacer for supporting the valve spring can be omitted.

  The valve spring may include a coil spring, the relief valve may further include a spacer that directly supports the valve spring, and the spacer may include an oil passage that communicates with the housing space and the hollow hole. Good. With this configuration, when the valve spring is supported by the spacer, the housing space in the valve sleeve and the outside of the cylinder can be communicated with each other via the oil discharge path portion of the spacer and the hollow hole of the retainer.

  Further, the valve spring includes a coil spring, the valve sleeve includes a case member directly supporting the valve spring, and a seat member fitted to the case member, and the seat member includes the valve seat. It is preferable that the case member has an oil drain passage communicating with the hollow hole. With this configuration, when the valve spring directly supports the valve spring, the housing space in the valve sleeve and the outside of the cylinder can be communicated with each other through the oil drain passage portion of the valve sleeve and the hollow hole of the retainer.

  As described above, according to the present invention, there is an advantage that the strength required for the valve sleeve can be reduced because it is possible to eliminate the fear that an excessive force is applied from the retainer to the relief valve. From this advantage, it is easy to use a thin pressed product or a resin product as the valve sleeve.

  In particular, it is preferable that the valve sleeve is formed of a resin. With this configuration, the valve sleeve can be easily formed by resin molding, and the valve sleeve can be reduced in weight.

  When the valve sleeve is a pressed product having a small thickness, press working becomes easy, and the inner diameter of the valve sleeve is enlarged to increase the accommodation space and the valve spring is enlarged to reduce the spring stress. It is easy to reduce the reduction and the spring constant.

  As described above, the present invention realizes a simple retainer mounting structure in which the opening pressure of the relief valve of the chain tensioner is stabilized by adopting the above-described configuration, and eliminates the need for machining the oil discharge passage to the cylinder. it can.

Sectional view showing a chain tensioner according to a first embodiment of the present invention. FIG. 2 is a front view showing a chain transmission including the chain tensioner of FIG. 1. Enlarged view around the relief valve in FIG. FIG. 2 is a plan view showing the retainer shown in FIG. 1 before press fitting. FIG. 4 is a sectional view taken along line VV in FIG. 4. Enlarged view of the vicinity of a relief valve according to a second embodiment of the present invention. Enlarged view of the vicinity of a relief valve according to a third embodiment of the present invention. Sectional view showing a chain tensioner according to a fourth embodiment of the present invention.

  A first embodiment as an example of the present invention will be described with reference to FIGS.

  FIG. 2 shows a chain transmission including the chain tensioner 1 according to the first embodiment. In this chain transmission, a sprocket 3 fixed to a crankshaft 2 of an engine and a sprocket 5 fixed to a camshaft 4 are connected via a chain 6, and the chain 6 controls the rotation of the crankshaft 2. The power is transmitted to the camshaft 4. The rotation of the camshaft 4 opens and closes a valve (not shown) of the combustion chamber.

  The chain 6 is in contact with a chain guide 8 supported so as to be swingable about a fulcrum shaft 7. The chain tensioner 1 presses the chain 6 via the chain guide 8.

  The chain tensioner 1 has a cylindrical cylinder 9 having one end closed and the other end opened. The cylinder 9 has an inner wall surface 10 along the virtual cylindrical surface. Mounting holes 11 are provided on both sides of the cylinder 9, respectively. The cylinder 9 is fixed to an engine block (not shown) by bolts (not shown) inserted into the respective mounting holes 11. Hereinafter, the direction along the center line of the virtual cylindrical surface of the inner wall surface 10 is referred to as “axial direction”.

  The chain tensioner 1 includes a plunger 12 slidably inserted in the cylinder 9 in an axial direction, a return spring 13 for urging the plunger 12 in a direction to protrude from the cylinder 9, and a back of the plunger 12 in the cylinder 9. The pressure chamber further includes a formed pressure chamber and an oil supply passage for introducing hydraulic oil into the pressure chamber.

  The oil supply passage 15 includes a flow passage formed as a member integral with the cylinder 9, has a check valve 16 at an end of the flow passage on the pressure chamber 14 side, and has an oil pump (not shown) at one end of the flow passage. )It is connected to the. The oil supply passage 15 introduces the working oil sent from the oil pump into the pressure chamber 14. A leak gap 17 is formed between the plunger 12 and the sliding surface of the cylinder 9.

  The chain tensioner 1 includes a relief valve 18 for releasing hydraulic oil from the inside of the pressure chamber 14 to the outside of the pressure chamber 14 when the pressure in the pressure chamber 14 becomes larger than a preset pressure, and a relief valve 18 for the cylinder 9. And a retainer 19 for fixing.

  The return spring 13 has one end supported by the check valve 16 and the other end pressing the plunger 12. The plunger 12 is urged in a direction protruding from the cylinder 9 by a return spring 13 disposed in the pressure chamber 14. The plunger 12 is in contact with the chain guide 8 at an end protruding from the cylinder 9. The plunger 12 has a cylindrical shape that closes a protruding end located on the chain guide 8 side and opens rearward. The center of the protruding end of the plunger 12 is formed of a plug 20 as an attachment part. The plug 20 is for forming an air vent passage for discharging air contained in the operating oil in the pressure chamber 14 between the plug 20 and the plunger body.

  The check valve 16 allows only the flow of hydraulic oil from the oil supply passage 15 to the pressure chamber 14. When the plunger 12 is pushed from the chain guide 8, the operating oil in the pressure chamber 14 flows out of the pressure chamber 14 through the leak gap 17.

  The relief valve 18 has a valve element 21, a valve spring 22 for urging the valve element 21 in the valve closing direction, and a valve sleeve 23 that houses the valve element 21 and the valve spring 22. The valve sleeve 23 has a valve seat portion 25 that forms a valve hole 24 corresponding to the valve element 21.

  As shown in FIGS. 1 and 3, the cylinder 9 has a stepped hole 26 into which the relief valve 18 can be inserted from outside the cylinder 9. The stepped hole 26 is a hole inner peripheral portion forming a series of holes communicating with the inside of the pressure chamber 14 and the outside of the cylinder 9, and has a smaller diameter hole 26 a continuous with the pressure chamber 14 and a smaller diameter hole 26 a. It has a large-diameter hole 26b having a large diameter and continuing to the outer surface of the cylinder 9, and a step 26c connecting the small-diameter hole 26a and the large-diameter hole 26b. The relief valve 18 is housed in the large diameter hole 26b. The retainer 19 is attached to the large diameter hole 26b.

  The valve body 21 is a spherical body that can open and close the valve hole 24 from the inside of the valve sleeve 23. The valve spring 22 is formed of a coil spring. A seat surface 27 on which the valve body 21 is seated is formed on the inner surface of the valve sleeve 23. The seat surface 27 has a shape depressed toward the valve hole 24. On the outer surface of the valve sleeve 23, an end portion supported by the step portion 26c of the stepped hole portion 26 and an outer peripheral fitting portion supported by the large diameter hole portion 26b are formed.

  The retainer 19 is formed of a toothed washer having an annular portion 29 forming a hollow hole 28 and an external tooth portion 30 pushed into a large-diameter hole portion 26b of the stepped hole portion 26. The annular portion 29 has an annular plate shape. The external teeth portion 30 is formed of teeth protruding from the annular portion 29. The external teeth portion 30 is bent from the annular portion 29 to the side opposite to the valve sleeve 23. The retainer 19 has a plurality of external teeth 30 around the annular portion 29 at a constant pitch.

  The retainer 19 is formed by pressing a metal plate. As such a retainer 19, for example, a JIS standard product may be adopted. 4 and 5 show a state before the retainer 19 is attached to the stepped hole portion 26. FIG. In this state, the diameter of the virtual circle circumscribing all the external teeth 30 of the retainer 19 is larger than the inner diameter of the large-diameter hole 26b shown in FIG. The retainer 19 is pressed into the large-diameter hole portion 26b by hitting the entire periphery of the annular portion 29 with the external teeth portion 30 facing the outside of the cylinder 9. In this press-fitting, since each external tooth portion 30 is further bent and pressed into the large diameter hole portion 26b as shown in FIG. 3, each external tooth portion 30 comes into strong contact with the large diameter hole portion 26b, The retainer 19 is attached to the stepped hole portion 26 by the engagement between the external tooth portion 30 and the large diameter hole portion 26b. In the press-fitting step of the retainer 19, when hitting the annular portion 29, the depth of pushing the retainer 19 into the large-diameter hole portion 26b and the striking force applied to the annular portion 29 are reduced to a predetermined value or less by machine control of the stroke and speed of the hitting tool. By limiting, it is possible to prevent an excessive force from being applied to the relief valve 18 from the retainer 19.

  The relief valve 18 further has a spacer 31 fitted to an end of the valve sleeve 23 opposite to the valve hole 24. The annular portion 29 of the retainer 19 is in contact with the spacer 31 and the valve sleeve 23. The relief valve 18 is pressed and fixed to the step portion 26 c of the stepped hole portion 26 by press-fitting the retainer 19. The spacer 31 may be fixed by press-fitting to the valve sleeve 23 or may be fixed by fitting to the valve sleeve 23 and abutting on the retainer 19.

  One end of the valve spring 22 is directly supported by the spacer 31, and the other end presses the valve element 21. By this pressing, the valve element 21 is urged in the valve closing direction. A rod 32 that regulates the amount of movement of the valve body 21 is formed integrally with the spacer 31. The valve spring 22 and the rod 32 are arranged coaxially. The rod 32 can support the inner periphery of the valve spring 22 so as to limit the inclination of the valve spring 22 with respect to the valve sleeve 23 to a certain value or less.

  The valve sleeve 23 is formed of a single cylindrical member capable of housing at least the valve element 21 and the valve spring 22 and forming a housing space 33 communicating with the valve hole 24. The valve sleeve 23 is formed of a resin. Note that the valve sleeve may be composed of a plurality of members, or may be formed of a metal material. For example, the entire valve sleeve may be formed integrally by press working using an iron-based material.

  The spacer 31 has an oil discharge passage 34 communicating with the housing space 33 in the valve sleeve 23 and the hollow hole 28 of the retainer 19. The housing space 33 in the valve sleeve 23 is a space for housing the valve body 21, the valve spring 22, and the like, and communicates with the valve hole 24. The oil drainage path portion 34 is formed of a pipe line extending straight from the tip end of the rod 32 facing the valve body 21 toward the hollow hole 28. The housing space 33 in the valve sleeve 23 communicates with the pressure chamber 14 through the valve hole 24 and the small-diameter hole 26 a, and also communicates with the outside of the cylinder 9 through the oil discharge path 34 of the spacer 31 and the hollow 28 of the retainer 19. Is in communication with

  When the pressure in the pressure chamber 14 becomes larger than a preset pressure, the valve body 21 separates from the seat surface 27 due to the pressure, whereby the relief valve 18 is opened. When the valve is opened, the hydraulic oil in the pressure chamber 14 passes through the valve hole 24, the housing space 33 in the valve sleeve 23, the oil discharge passage 34 of the spacer 31, and the hollow hole 28 of the retainer 19 in this order. Is discharged from the cylinder 9 to the outside of the cylinder 9 or further to the large-diameter hole 26b. At this time, the tip of the rod 32 receives the valve body 21 to regulate the amount of movement of the valve body 21, and restricts the flow rate of hydraulic oil passing through the valve hole 24. On the other hand, when the pressure in the pressure chamber 14 becomes smaller than the preset pressure, the valve body 21 is seated on the seat surface 27 by the urging force of the valve spring 22, and the relief valve 18 is closed.

  An annular accommodation groove 35 is formed on the inner periphery of the cylinder 9, and a register ring 36 is accommodated in the accommodation groove 35 so as to be movable in the axial direction. The register ring 36 has a ring shape lacking a part of the circumference and is elastically deformable in the radial direction. The register ring 36 elastically fastens the outer periphery of the plunger 12 and engages with any one of a plurality of circumferential grooves 37 formed on the outer periphery of the plunger 12 at regular intervals in the axial direction. In each of the circumferential grooves 37, when a load in the projecting direction is applied to the plunger 12, a taper surface that allows the plunger 12 to move by expanding the diameter of the register ring 36 and a load in the pushing direction to the plunger 12. A stopper surface is provided to lock the register ring 36 and limit the movement of the plunger 12 when a load is applied.

  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 12 moves in the pushing direction due to the tension of the chain 6, and absorbs the tension of the chain 6. At this time, the damper force is generated due to the viscous resistance of the hydraulic oil flowing out of the pressure chamber 14 through the leak gap 17, so that the plunger 12 moves slowly.

  On the other hand, when the tension of the chain 6 decreases during operation of the engine, the plunger 12 moves in the projecting direction by the urging force of the return spring 13 and absorbs the slack of the chain 6. At this time, the check valve 16 is opened, and the operating oil flows from the oil supply passage 15 into the pressure chamber 14, so that the plunger 12 moves quickly.

  When the plunger 12 repeatedly moves forward and backward due to the vibration of the chain 6, the register ring 36 moves back and forth in the receiving groove 35. When the range of movement of the plunger 12 in the protruding direction exceeds the movable range of the register ring 36 in the accommodation groove 35 due to the slack of the chain 6, the tapered surface in the circumferential groove 37 moves the register ring 36. The plunger 12 is allowed to move by expanding the diameter. At this time, the register ring 36 engages with the adjacent circumferential groove 37.

  When the engine resonates and the tension of the chain 6 suddenly increases, the relief valve 18 opens to release the pressure in the pressure chamber 14 and prevent the chain 6 from being over-tensioned.

  When the engine rotates at a high rotation speed, the pressure in the pressure chamber 14 oscillates at a high frequency, and the valve body 21 of the relief valve 18 cannot follow the pressure fluctuation, so that the relief valve 18 remains open. there is a possibility. In this case, if the flow rate of the hydraulic oil passing through the relief valve 18 is large, the damper function of the chain tensioner 1 decreases, and the amplitude of the plunger 12 increases. In the chain tensioner 1, since the movement amount of the valve body 21 is regulated by the rod 32, the flow rate of the hydraulic oil passing through the relief valve 18 is suppressed, and the reduction of the damper effect hardly occurs.

  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 36 and the circumferential groove 37 prevents the plunger 12 from moving in the pushing direction. Is done. Therefore, when the engine is restarted, the chain 6 is unlikely to be loosened, and the engine can be started smoothly.

  When the engine is stopped, the oil pump is stopped and the level of the hydraulic oil in the oil supply passage 15 is lowered. For this reason, when the engine is restarted, air may be mixed into the hydraulic oil supplied to the pressure chamber 14 through the oil supply passage 15. In this case, the air mixed into the pressure chamber 14 It is discharged through 12 air vent passages. Therefore, a reduction in the damper action due to the air in the pressure chamber 14 is unlikely to occur.

  The chain tensioner 1 is as described above, and the external teeth pushed into the large-diameter hole 26b by press-fitting the retainer 19 formed of a toothed washer into the large-diameter hole 26b of the stepped hole 26. The portion 30 and the large-diameter hole 26b are engaged, and the engagement allows the retainer 19 to be attached to the large-diameter hole 26b and the relief valve 18 to be fixed to the cylinder 9. For this reason, the chain tensioner 1 does not require female threading in the stepped hole 26, and does not require application of a loosening agent or a screwdriver, thereby easily attaching the retainer 19 to the large-diameter hole 26b. As a result, the contact portion of the large-diameter hole portion 26b with the retainer 19 can be formed in a simple shape, for example, a cylindrical surface having no internal thread, thereby reducing the processing cost.

  Further, when the retainer 19 is press-fitted into the large-diameter hole 26b, the chain tensioner 1 limits the depth and the impact force of the retainer 19 into the large-diameter hole 26b on the side of the striking tool that hits the retainer 19. Since the excessive force is not applied to the relief valve 18 from the retainer 19, that is, the urging force of the valve spring 22 can be prevented from becoming excessive, the valve opening pressure of the relief valve 18 is stabilized.

  Further, since the chain tensioner 1 employs the retainer 19 formed of a toothed washer, the housing space 33 in the valve sleeve 23 and the outside of the cylinder 9 are communicated via the hollow hole 28 of the retainer 19, and the communication path is provided. Thus, the hydraulic oil can be discharged to the outside of the cylinder 9, thereby eliminating the need for forming a drain oil passage branched from the stepped hole portion 26 in the cylinder 9. As a result, the processing cost of the cylinder 9 can be reduced.

  As described above, the chain tensioner 1 can realize a simple retainer mounting structure in which the valve opening pressure of the relief valve 18 is stabilized, and can obviate the need for machining of an oil discharge passage to the cylinder 9, and furthermore, an inexpensive chain tensioner. Can be provided as

  In the chain tensioner 1, the valve spring 22 includes a coil spring, the relief valve 18 includes a spacer 31 that directly supports the valve spring 22, and the spacer 31 includes a housing space 33 in the valve sleeve 23 and a hollow hole in the retainer 19. Since the oil discharge passage 34 communicates with the valve spring 28, when the spacer 31 supports the valve spring 22, the housing space 33 of the valve sleeve 23 and the outside of the cylinder 9 are separated from the oil discharge passage 34 of the spacer 31 and the retainer 19. The communication can be made through the hollow hole 28.

  Further, in the chain tensioner 1, since the valve sleeve 23 is formed of resin, the valve sleeve 23 can be easily formed by resin molding, and the weight can be reduced as compared with the case where the valve sleeve 23 is made of metal. Can be.

  In the first embodiment, the spacer 31 is employed to support the valve spring 22 and regulate the valve element 21, but a relief valve in which the spacer is omitted may be employed. FIG. 6 shows a second embodiment as an example. In the following, only differences from the first embodiment will be described.

  In the relief valve 40 according to the second embodiment, the dimensions of the valve sleeve 42 and the large-diameter hole 43 are reduced because the spacer for supporting the valve spring 41 is omitted.

  The annular portion 46 that forms the hollow hole 45 of the retainer 44 has a support protrusion 47 that receives the inner circumference of the valve spring. The end of the valve spring 41 opposite to the valve body 21 is directly supported by the annular plate portion of the annular portion 46 from the opening of the valve sleeve 42. The hollow hole 45 of the retainer 44 communicates directly with the accommodation space in the valve sleeve 42. The support protrusion 47 is formed in a cylindrical shape protruding from the annular plate portion of the annular portion 46 toward the valve body 21. The support protrusion 47 improves the rigidity of the annular portion 46.

  The support projection 47 and the valve spring 41 are arranged coaxially. The support protrusion 47 can support the inner periphery of the valve spring 41 so as to limit the inclination of the valve spring 41 with respect to the valve sleeve 42 to a certain value or less.

  In the chain tensioner according to the second embodiment, the opposite side of the valve body 41 of the valve spring 41 is directly supported by the retainer 44, so that the spacer of the first embodiment can be omitted.

  In the first embodiment and the second embodiment, the valve sleeve made of a single member is exemplified, but the valve sleeve can be made up of a plurality of members. FIG. 7 shows a third embodiment as an example.

  The relief valve 50 according to the third embodiment has a valve sleeve 52 including a case member 53 that directly supports the valve spring 51 on the side opposite to the valve element 21, and a seat member 54 fitted to the case member 53. . The seat member 54 has a valve seat portion 56 that forms a valve hole 55. The inner periphery of the case member 53 can support the outer periphery of the valve spring 51 so as to limit the inclination of the valve spring 51 with respect to the valve sleeve 52 to a certain value or less. The annular portion 29 of the retainer 19 is in contact with the case member 53. The case member 53 has an oil drain passage 57 communicating with the hollow hole 28 of the retainer 19. The housing space 59 in the valve sleeve 52 communicates with the oil discharge passage 57 of the case member 53.

  The chain tensioner according to the third embodiment, when directly supporting the valve spring 51 with the valve sleeve 52, connects the housing space 59 of the valve sleeve 51 and the outside of the cylinder to the oil drain passage 57 of the valve sleeve 52 and the retainer 19. The communication can be made through the hollow hole 28.

  In the first embodiment and the like, the registering system is exemplified as the no-back mechanism of the chain tensioner. However, the no-back mechanism may be omitted or another system may be used. FIG. 8 shows a fourth embodiment as an example employing another method.

  In the chain tensioner according to the fourth embodiment, the plunger 62 inserted into the cylinder 61 has the female screw 63. A screw rod 65 having a male screw 64 is housed inside the plunger 62. The return spring 66 is interposed between the screw rod 65 and the plunger 62. The space inside the screw rod 65 and the inside space of the plunger 62 communicating therewith are configured as a pressure chamber 67. A check valve 69 is provided between the pressure chamber 67 and the oil supply passage 68. The female screw 63 and the male screw 64 are formed in a sawtooth shape in which the flank angle of the flank on which the plunger is pushed is larger than the flank angle of the flank on which the plunger protrudes, and are screwed together. Here, the flank into which the plunger is pushed is a surface on the side where the female screw 63 contacts the male screw 64 when the plunger 62 is pushed into the cylinder 61, and the flank on the plunger protruding side is a male screw when the plunger 62 projects from the cylinder 61. The surface corresponding to 64.

  When the chain becomes loose, the plunger 62 protrudes from the cylinder 61 while rotating relative to the screw rod 65 by a component force acting on the flank contact portion between the female screw 63 and the male screw 64.

  On the other hand, when the engine stops, the supply of hydraulic oil to the pressure chamber 67 stops, and the plunger 62 tries to be pushed into the cylinder 61. When the plunger 62 is pushed, the engagement between the female screw 63 and the male screw 64 causes the female screw 63 and the male screw 64 to engage. A large resistance is added to the relative rotation of the plunger 64, and the plunger 62 is prevented from being pushed.

  The embodiments disclosed this time should be considered in all respects as illustrative and not restrictive. Therefore, 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.

1 Chain tensioner 9, 61 Cylinder 12, 62 Plunger 13, 66 Return spring 14, 67 Pressure chamber 15, 68 Oil supply passage 18, 40, 50 Relief valve 19, 44 Retainer 21 Valve body 22, 41, 51 Valve spring 23, 42 , 52 Valve sleeve 24, 55 Valve hole 25, 56 Valve seat 26 Stepped hole 28, 45 Hollow hole 29, 46 Annular part 30 External tooth 31 Spacer 33, 59 Housing space 34 Oil drainage channel 47 Support projection 53 Case member 54 Seat member 57 Oil drain passage

Claims (5)

A cylinder, a plunger slidably inserted into the cylinder, a return spring for urging the plunger in a direction protruding from the cylinder, and a pressure chamber formed behind the plunger in the cylinder, An oil supply passage for introducing hydraulic oil into the pressure chamber, a relief valve for releasing the hydraulic oil from the pressure chamber to the outside of the pressure chamber when the pressure in the pressure chamber becomes larger than a preset pressure, and the relief valve And a retainer that fixes the cylinder to the cylinder,
The relief valve has a valve element, a valve spring that urges the valve element in a valve closing direction, and a valve sleeve that houses the valve element and the valve spring. Having a valve seat portion forming a corresponding valve hole in the body,
In the chain tensioner, wherein the cylinder has a stepped hole through which the relief valve can be inserted from outside the cylinder,
The retainer includes a toothed washer having an annular portion forming a hollow hole and external teeth pressed into the stepped hole, and the retainer is configured to engage the external teeth with the stepped hole. A chain tensioner, which is attached to the stepped hole portion by a combination, and a housing space in the valve sleeve communicates with the outside of the cylinder through the hollow hole. The valve spring comprises a coil spring;
The chain tensioner according to claim 1, wherein the valve spring is directly supported by the annular portion of the retainer, and the annular portion has a support protrusion that receives an inner circumference of the valve spring. The valve spring comprises a coil spring,
2. The chain tensioner according to claim 1, wherein the relief valve further includes a spacer that directly supports the valve spring, and the spacer has an oil passage that communicates with the housing space and the hollow hole. 3. The valve spring comprises a coil spring;
The valve sleeve comprises a case member directly supporting the valve spring, and a seat member fitted to the case member, wherein the seat member has the valve seat portion, and the case member is The chain tensioner according to claim 1, further comprising an oil discharge passage communicating with the hollow hole.   The chain tensioner according to claim 1, wherein the valve sleeve is formed of a resin.

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