JP2020041611A - Chain tensioner - Google Patents

Abstract

To provide a chain tensioner that has excellent followability to looseness of a chain and a reduced outflow of oil.SOLUTION: A chain tensioner comprises: a cylindrical cylinder 9; a cylindrical plunger 10; a return spring 33 configured to bias the plunger 10; a pressure chamber 18 changing its volume with the axial movement of the plunger 10; a check valve 20 having a valve seat 21 and a check ball 25; a leak clearance formed between the outer periphery of the plunger 10 and the inner periphery of the cylinder 9 and configured to leak an oil from the pressure chamber 18; an oil supply passage 31 configured to introduce the oil from the outside to the inside of the cylinder 9; and a communication passage 30 configured to provide communication between the leak clearance and the inside of the plunger 10. A notch 21c is formed in the outer periphery of the valve seat 21, and a spiral groove 23 is formed in the valve seat 21 or in a component arranged between the valve seat 21 and the plunger 10 to form an orifice passage A. The oil in the pressure chamber 18 flows into the inside of the plunger 10 through the orifice passage A.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a chain tensioner.

  Examples of a chain transmission device used for an engine of an automobile or the like include a device that transmits rotation of a crankshaft to a camshaft, a device that transmits rotation of a crankshaft to an auxiliary device such as an oil pump, and a device that transmits rotation of a crankshaft to a balancer shaft Or an engine that connects an intake cam and an exhaust cam of a twin cam engine to each other. A chain tensioner is used to keep the chain tension of these chain transmissions in an appropriate range.

  In general, a chain tensioner generates a hydraulic damper by oil supply from an engine to keep the fluctuation of the chain tension constant. However, since oil supply is stopped when the engine is stopped, a predetermined hydraulic damper may not be able to be generated after the engine is started until the pressure chamber inside the chain tensioner is filled with oil. In such a case, there is a problem that the tensioner is pushed in greatly, and the chain flutters and abnormal noise is generated. Therefore, many chain tensioners are provided with a mechanism called a no-back mechanism to prevent the plunger from being pushed in beyond a certain amount.

  In addition, by circulating oil inside the chain tensioner, oil is prevented from flowing out of the chain tensioner, and by storing the oil inside the chain tensioner, a hydraulic damper can be generated immediately after the engine starts. There is also a chain tensioner (for example, see Patent Documents 1 and 2).

  For example, a chain tensioner 40 shown in FIG. 9 includes a cylindrical cylinder 9 having one end opened and the other end closed, a plunger 10 supported on the inner periphery of the cylinder 9 so as to be slidable in the axial direction, and a plunger 10. The plunger 10 includes a reservoir chamber 27 formed inside the cylinder 10 and a pressure chamber 18 formed at the other end of the plunger 10 in the cylinder 9 and having a volume that changes with the axial movement of the plunger 10.

  The cylinder 9 has an oil supply passage 31 for introducing oil supplied by an oil pump, and the oil supply passage 31 is opened in an oil supply space 28 formed between the outer periphery of the plunger 10 and the inner periphery of the cylinder 9. are doing. A leak gap is formed between the outer circumference of the plunger 10 and the inner circumference of the cylinder 9, and the leak gap and the oil supply space 28 communicate with the reservoir chamber 27 through the communication passage 30.

Japanese Patent Publication No. 3-010819 JP 2015-183767 A

  In the chain tensioner 40, in order to suppress the amount of oil flowing out, it is preferable that the leak gap is small.

  On the other hand, in order to adjust the damping force of the chain tensioner 40, it is necessary to adjust the size of the leak gap. Therefore, for example, in an engine that does not require a high damping force, it is necessary to increase the size of the first leak gap 19 from the pressure chamber 18 to the oil supply space 28. However, when the size of the first leak gap 19 is increased, the size of the second leak gap 29 extending from the oil supply space 28 to one end of the cylinder 9 is also increased, so that the amount of oil flowing out of the second leak gap 29 to the outside is increased. Leads to

  Accordingly, an object of the present invention is to provide a suitable chain tensioner which is excellent in followability to looseness of a chain and has a small oil outflow amount.

  In order to solve the above problems, the present invention provides a cylindrical cylinder having one end opened and the other end closed, and an axially slidably supported inner end of the cylinder, and an insertion end into the cylinder having an open end. A cylindrical plunger whose protruding end from the cylinder is closed, a return spring for urging the plunger in a direction to protrude from the cylinder, and the cylinder so that the volume changes with the axial movement of the plunger. A pressure chamber formed therein, a valve seat provided at a lower end portion of the cylinder, and a valve body that opens and closes a valve hole of the valve seat. Oil from the inside of the plunger to the pressure chamber is provided. A check valve that allows only flow, and is formed between the outer circumference of the plunger and the inner circumference of the cylinder, and when the volume of the pressure chamber is reduced, oil is leaked from the pressure chamber. A leak gap, an oil supply passage for introducing oil from the outside of the cylinder to the inside, and a communication passage communicating the leak gap with the inside of the plunger, wherein a notch is formed on the outer periphery of the valve seat. A helical groove forming an orifice passage is formed in the valve seat or a member disposed between the valve seat and the plunger, and the pressure in the pressure chamber becomes higher than the pressure inside the plunger. In this case, a chain tensioner is used in which oil in the pressure chamber flows into the plunger through the notch and the orifice passage.

  At this time, the member disposed between the valve seat and the plunger is a plate, and the spiral groove is formed on the other end surface of the plate, and the spiral groove and the valve seat are formed. The orifice passage can be formed between the first end face and the one end side.

  The helical groove is formed on the end face on the one end side of the valve seat, and the helical groove and the end face on the other end side of a member disposed between the valve seat and the plunger are formed. The orifice passage can be formed therebetween.

  Further, the spiral groove is formed on the end face on the one end side of the valve seat, and the orifice passage can be formed between the spiral groove and the end face of the plunger.

  In each of these configurations, a configuration is adopted in which the amount of oil flowing out of the pressure chamber by the orifice passage is set to be larger than the amount of oil flowing out of the pressure chamber by the leak gap. be able to.

  Further, it is possible to employ a configuration in which an oil supply space communicating with the leak gap is formed between the outer periphery of the plunger and the inner periphery of the cylinder.

  The oil supply space may be formed on the entire outer periphery of the plunger, and a step portion connected to the leak gap may be formed at the other end of the oil supply space.

  The present invention forms a notch on the outer periphery of a valve seat of a check valve that allows only the flow of oil from the inside of the plunger to the pressure chamber, and is disposed between the valve seat or the valve seat and the plunger. A spiral groove constituting an orifice passage was formed in the member, and the cutout and the orifice passage were set so that oil could flow from the pressure chamber into the plunger. Thus, the damping force can be adjusted by the specification of the orifice passage without relying on the adjustment of the size of the leak gap for the damping force adjustment. For this reason, it is possible to set the damping characteristic of the chain tensioner that can correspond to a wide range of engine characteristics while maintaining the leak gap in a small state and suppressing the outflow of oil. Further, the amount of oil consumed by the chain tensioner, that is, the amount of oil flowing out of the chain tensioner from the leak gap can be suppressed.

  Further, when the plunger receives a load input in the pushing direction, the oil in the pressure chamber flows directly into the plunger through the orifice passage, so that the plunger moves in the protruding direction, so that oil supply to the pressure chamber is required. In this case, the oil inside the plunger can be used. For this reason, a damper force can be generated immediately after the engine is started.

Overall view showing a chain transmission incorporating a chain tensioner (A) is a right side view of the chain tensioner of FIG. 1, and (b) is a rear view thereof. Longitudinal sectional view showing a chain tensioner according to a first embodiment of the present invention. 3A and 3B show a valve seat provided in the check valve of FIG. 3, wherein FIG. 3A is a front view, and FIG. 3B is a right side view of FIG. 3A and 3B show a plate disposed on one end side of the valve seat in FIG. 3, wherein FIG. 3A is a front view, and FIG. 3B is a right side view of FIG. Longitudinal sectional view showing a chain tensioner according to a third embodiment of the present invention. 6A and 6B show a valve seat provided in the check valve of FIG. 6, wherein FIG. 6A is a left side view of FIG. 6B, FIG. 6B is a front view, and FIG. Longitudinal sectional view showing a chain tensioner according to a fourth embodiment of the present invention. Longitudinal sectional view showing a conventional chain tensioner

  FIG. 1 shows a chain transmission incorporating a chain tensioner 1 according to a first embodiment of the present invention. In this chain transmission, a sprocket 3 fixed to a crankshaft 2 of an engine and a sprocket 5 fixed to two camshafts 4 are connected via a chain 6. The chain 6 transmits the rotation of the crankshaft 2 to the camshaft 4 and rotates the camshaft 4 to open and close the valve of the combustion chamber.

  The rotation direction of the crankshaft 2 when the engine is operating is constant (right rotation in FIG. 1), and at this time, the chain 6 is pulled into the sprocket 3 with the rotation of the crankshaft 2 (see FIG. 1). The portion on the right side is the tension side, and the portion on the side sent out from the sprocket 3 (the left side in FIG. 1) is the slack side. Then, a chain guide 8 supported swingably around a fulcrum shaft 7 is in contact with the slack side portion of the chain 6. The chain tensioner 1 presses the chain 6 via the chain guide 8.

  As shown in FIGS. 2 and 3, the chain tensioner 1 has a cylindrical cylinder 9 having one end opened and the other end closed, and a plunger 10 supported on the inner periphery of the cylinder 9 so as to be slidable in the axial direction. And A protruding end 17 of the plunger 10 protruding from one end of the cylinder 9 presses the chain guide 8.

  The cylinder 9 is integrally formed of metal (for example, aluminum alloy). The cylinder 9 is fixed to the engine wall by tightening bolts 12 inserted into holes 11a (see FIG. 2B) of a plurality of mounting pieces 11 integrally formed on the outer periphery of the cylinder 9. The cylinder 9 is mounted on the engine wall so that the direction in which the plunger 10 projects from the cylinder 9 is obliquely upward.

  The plunger 10 is formed in a tubular shape in which the other end inserted into the cylinder 9 is open and the protruding end 17 from the one end of the cylinder 9 is closed. The material of the plunger 10 is an iron-based material (for example, a steel material such as SCM (chrome molybdenum steel) or SCr (chrome steel)).

  At the other end in the cylinder 9, a pressure chamber 18 whose volume changes with the axial movement of the plunger 10 is formed. The volume of the pressure chamber 18 increases when the plunger 10 moves in the protruding direction, and decreases when the plunger 10 moves in the pushing direction.

  The outer circumferences 15 and 32 of the maximum diameter portion of the plunger 10 are cylindrical surfaces, and the inner circumference 14 of the cylinder 9 is also a cylindrical surface. The size of the gap between the outer circumferences 15 and 32 of the maximum diameter portion of the plunger 10 and the inner circumference 14 of the cylinder 9 is very small, and is set in the range of 0.005 to 0.10 mm in radius difference. The gap between the outer circumferences 15 and 32 of the largest diameter portion of the plunger 10 and the inner circumference 14 of the cylinder 9 is a leak gap that leaks oil from the pressure chamber 18 when the volume of the pressure chamber 18 is reduced.

  An oil supply space 28 communicating with the leak gap is formed between the outer periphery of the plunger 10 and the inner periphery of the cylinder 9. The oil supply space 28 is formed annularly between the concave portion 16 formed on the entire outer periphery of the plunger 10 and the inner periphery 14 of the cylinder 9.

  The recess 16 for forming the oil supply space 28 is provided at the axial center of the plunger 10, and the outer circumferences 15 and 32 of the largest diameter portion of the plunger 10 are provided at one end and the other end of the recess 16, respectively. Exists. Hereinafter, the leak gap on the other end side of the recess 16, that is, on the pressure chamber 18 side is referred to as a first leak gap 19, and the leak gap on one end side of the recess 16, that is, on the protruding end 17 side of the plunger 10 is a second leak gap. This is referred to as a leak gap 29.

  A step 35 connected to the first leak gap 19 is formed at the other end of the oil supply space 28. A step 36 connected to the second leak gap 29 is formed at one end of the oil supply space 28.

  The steps 35 and 36 are always located in the cylinder 9 irrespective of the position of the plunger 10. That is, the entire outer periphery 15 of the largest diameter portion of the plunger 10 constituting the first leak gap 19 is always accommodated in the cylinder 9. For this reason, when the plunger 10 moves in the axial direction according to the fluctuation in the tension of the chain 6, the axial length of the first leak gap 19 does not change. Therefore, a constant damping force can be exerted regardless of the position of the plunger 10 in the axial direction.

  A check valve that allows only the flow of oil from the inside of the plunger 10 to the pressure chamber 18 side and restricts the flow of oil from the pressure chamber 18 to the inside of the plunger 10 at the insertion end of the plunger 10 into the cylinder 9. 20 are provided. The check valve 20 has a valve seat 21, a check ball 25, and a retainer 26. The valve seat 21 is provided at an insertion end of the plunger 10 into the cylinder 9. Therefore, when the plunger 10 is inserted into the cylinder 9, the valve seat 21 is provided at the lower end of the cylinder 9. The valve seat 21 is provided with a valve hole 21a penetrating in the axial direction. The check ball 25 is a spherical valve body that opens and closes the valve hole 21a from the pressure chamber 18 side. The retainer 26 regulates the moving range of the check ball 25.

  The internal space of the plunger 10 is a reservoir chamber 27 having a diameter larger than the diameter of the valve hole 21a of the check valve 20.

  A return spring 33 is incorporated in the pressure chamber 18. The other end of the return spring 33 is supported by the bottom portion 13 of the cylinder 9, and one end presses the plunger 10, thereby urging the plunger 10 in the direction in which the plunger 10 protrudes from the cylinder 9. In this embodiment, the return spring 33 presses the plunger 10 via the valve seat 21 of the check valve 20, but the return spring 33 may directly press the plunger 10.

  The plunger 10 is provided with a communication passage 30 that communicates between the oil supply space 28 and the reservoir chamber 27. The communication passage 30 communicates with the first leak gap 19 and the second leak gap 29 through the oil supply space 28.

  The communication passage 30 is provided so as to be located on the upper half circumference of the plunger 10 with the mounting piece 11 of the cylinder 9 fixed to the engine wall surface. Specifically, the communication passage 30 is provided in an upper portion in the radial direction of the plunger 10 and within a range corresponding to a half of the outer peripheral dimension of the plunger 10. In particular, in this embodiment, the communication passage 30 is It is provided so as to be located on the top of the outer circumference of the ten. Therefore, when air exists inside the reservoir chamber 27, the air can be smoothly discharged from the communication passage 30.

  Further, as shown in FIG. 3, the cylinder 9 is provided with an oil supply passage 31 for introducing oil from outside to inside of the cylinder 9. The oil supply passage 31 is a through hole that penetrates the cylinder 9 in the radial direction. An inlet 34 of the oil supply passage 31 (see FIG. 2B) is connected to an oil supply port on the engine wall side. The outlet of the oil supply passage 31 opens to the cylindrical surface on the inner periphery of the cylinder 9 and faces the oil supply space 28. The oil supplied from the oil pump of the engine is introduced into the cylinder 9 from outside through the oil supply passage 31.

  An orifice passage A defined by a spiral groove 23 is provided between the valve seat 21 and the plunger 10. When the pressure in the pressure chamber 18 becomes higher than the pressure in the reservoir chamber 27, the oil in the pressure chamber 18 returns to the reservoir chamber 27 through the orifice passage A. That is, the orifice passage A serves as an oil return path from the pressure chamber 18 to the reservoir chamber 27 on the back side (plunger 10 side) of the check valve 20.

  By providing the oil return path, the damping force can be adjusted according to the specification of the orifice passage A without depending on the adjustment of the size of the leak gap. For this reason, the damping characteristic of the chain tensioner 1 that can cope with a wide range of engine characteristics can be set while maintaining the leak gap in a small state and suppressing the outflow of oil. The specification of the orifice passage A can be set by replacing the valve seat 21 or the like with an appropriate one, and does not require a design change of main parts such as the plunger 10.

  When the plunger 10 receives a load input in the pushing direction, the oil in the pressure chamber 18 flows directly into the reservoir chamber 27 through the orifice passage A. Therefore, when it is necessary to supply oil into the pressure chamber 18 so that the plunger 10 moves in the protruding direction, the oil in the reservoir chamber 27 can be used immediately as oil for supplying to the pressure chamber 18. . Therefore, the amount of oil flowing out of the leak gap from the chain tensioner 1 can be suppressed, and as a result, the chain tensioner 1 can generate a damper force immediately after the engine is started.

  Here, in the first embodiment shown in FIGS. 3 to 5, the plate 22 is disposed between the valve seat 21 of the check valve 20 and the end face 10 a of the plunger 10, and the spiral shape formed on the plate 22 is formed. The groove 23 forms the orifice passage A.

  As shown in FIG. 4, the valve seat 21 has a protrusion 21 d at the center thereof toward the other end, and a valve hole 21 a in the axial direction penetrating the front and back of the valve seat 21 through the protrusion 21 d. ing. The check ball 25 comes into contact with and separates from the end opening of the valve hole 21a on the protruding portion 21d side.

  Further, the valve seat 21 has a notch 21c in a part of the outer periphery 21b. The portion provided with the notch 21c does not come into contact with the inner periphery of the plunger 10, and a gap is interposed between the notch 21c and the inner periphery of the plunger 10. Since the notch 21c is formed over the entire length of the valve seat 21 in the front and back directions, the gap between the notch 21c and the inner periphery of the plunger 10 is also set to the entire length of the valve seat 21 in the front and back directions. The outer periphery 21 b other than the notch 21 c abuts on the inner periphery of the plunger 10.

  The notch 21c in FIG. 4 is a flat outer surface extending in a tangential direction of a circle around the axis of the valve seat 21, but the shape of the notch 21c can be freely set. For example, the notch 21c may have a concave shape that is dented in the inner diameter direction.

  As shown in FIG. 5, the plate 22 has an axial hole 22a at the center thereof, which penetrates the front and back of the plate 22. The hole 22a is connected to the valve hole 21a of the valve seat 21. When the check valve 20 is opened, the pressure chamber 18 and the reservoir chamber 27 communicate with each other through the valve hole 21a and the hole 22a.

  The plate 22 has a notch 22c in a part of the outer periphery 22b. The portion provided with the notch 22c does not come into contact with the inner periphery of the plunger 10, and a gap exists between the notch 22c and the plunger 10. Since the notch 22c is formed over the entire length of the plate 22 in the front and back direction, the gap between the notch 22c and the inner periphery of the plunger 10 is also set to the entire length of the plate 22 in the front and back direction. The outer periphery 22b other than the notch 22c contacts the inner periphery of the plunger 10.

  The notch 22c in FIG. 5 is a flat outer surface extending in the tangential direction of a circle around the axis of the plate 22, but the shape of the notch 22c can be freely set. For example, the notch 22c may have a concave shape that is depressed in the inner diameter direction.

  A spiral groove 23 is formed on an end face 22e on the other end of the plate 22 facing the valve seat 21 side. The spiral groove 23 is a groove whose valve seat 21 side is open. A space in the groove is closed by an end surface 21e on one end side of the valve seat 21 opposed in the axial direction, and a spiral orifice passage having only an inlet 23a on the outer diameter side and an outlet 23b on the inner diameter side is opened. Constitute. The entrance 23a of the spiral groove 23 faces the notch 22c at the outermost portion of the spiral. The outlet 23b of the spiral groove 23 faces the hole 22a at the smallest diameter portion of the spiral. The notch 21c of the valve seat 21 and the notch 22c of the plate 22 are arranged in directions overlapping with each other in the direction around the axis.

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

  When the tension of the chain 6 increases during operation of the engine, the plunger 10 moves in the pushing direction into the cylinder 9 due to the tension of the chain 6, and absorbs the tension of the chain 6. Since the volume of the pressure chamber 18 decreases in accordance with the movement of the plunger 10, the pressure in the pressure chamber 18 becomes higher than the pressure in the reservoir chamber 27 inside the plunger 10, and the check valve 20 closes. Then, oil flows from the pressure chamber 18 to the oil supply space 28 through the first leak gap 19. At this time, a damper force is generated by viscous resistance of the oil flowing through the first leak gap 19, and the plunger 10 moves slowly. Further, oil flows from the oil supply space 28 into the reservoir chamber 27 through the communication passage 30.

  At this time, since the pressure in the pressure chamber 18 is higher than the pressure in the reservoir chamber 27, the oil in the pressure chamber 18 is supplied to the notch 21c of the valve seat 21, the notch 22c of the plate 22, and the orifice. It flows into the reservoir chamber 27 through the passage A.

  The oil in the pressure chamber 18 returns to the reservoir chamber 27 through the notch 21c of the valve seat 21 and the path passing through the orifice passage A in addition to the path passing through the first leak gap 19, the oil supply space 28, and the communication path 30. The amount of oil flowing out of the second leak gap 29 to the outside of the cylinder 9 is reduced by the amount of the oil returned through both paths.

  At this time, the amount of oil flowing out of the pressure chamber 18 through the orifice passage A (same as above) is smaller than the amount of oil flowing out of the pressure chamber 18 through the first leak gap 19 (for example, the amount of oil flowing out per unit time). If it is set to be larger, the amount of oil flowing out of the cylinder 9 from the second leak gap 29 can be further reduced.

  On the other hand, when the tension of the chain 6 decreases during operation of the engine, the plunger 10 moves in the projecting direction by the urging force of the return spring 33, and absorbs the slack of the chain 6. At this time, since the volume of the pressure chamber 18 increases in accordance with the movement of the plunger 10, the pressure of the pressure chamber 18 becomes lower than the pressure of the reservoir chamber 27, and the check valve 20 opens. Then, the oil flows from the reservoir chamber 27 into the pressure chamber 18 through the valve hole 21a of the check valve 20, so that the plunger 10 moves quickly. At this time, oil is introduced into the reservoir chamber 27 from the outside of the cylinder 9 through the oil supply passage 31, the oil supply space 28, and the communication passage 30 by the pressure of the oil pump. For this reason, the pressure in the reservoir chamber 27 does not easily drop, and the chain 6 is excellent in following up the slack.

  Further, in the chain tensioner 1, since the reservoir chamber 27 having a diameter larger than the diameter of the valve hole 21a of the check valve 20 is formed inside the plunger 10, the amount of oil stored in the plunger 10 is increased. Can be secured. For this reason, immediately after the engine is started, even when there is no oil supply from the engine to the chain tensioner 1, the damper force can be generated by using the oil stored inside the plunger 10.

  In the first embodiment, the spiral groove 23 forming the orifice passage A is formed in the orifice plate 22 which is a member arranged between the valve seat 21 and the end face 10a of the plunger 10. The seat 21 itself can also be used without changing the conventional one. Alternatively, even when the axial thickness of the valve seat 21 is made thinner than before by the interposition of the plate 22, the spiral groove 23 is a member separate from the valve seat 21 having a complicated shape. Since it is formed on a certain plate 22, its processing is easy.

  As a second embodiment of the present invention, the following embodiment in which the configuration of the orifice passage A is different can be adopted.

  In the second embodiment, a spiral groove 23 forming the orifice passage A is formed on an end face 22f on one end side of a plate 22 disposed between the valve seat 21 and the plunger 10. A shim made of a plate-like member is arranged between the plate 22 and the end face 10a of the plunger 10. The plate 22 is made of the same member as that of the first embodiment shown in FIG. 5, and the surface on which the spiral groove 23 is formed is on the opposite side (plunger 10 side) from the first embodiment. They are different in that they are arranged facing.

  The spiral groove 23 is a groove whose shim side is open. The space in the groove is closed by the end face on the other end side of the shim facing in the axial direction, and forms a spirally continuous orifice passage A. The shim has a hole in the center thereof, and the oil flowing out of the outlet 23b of the spiral groove 23 through the notch 21c, the notch 22c and the orifice passage A passes through the hole 22a of the plate 22 and the hole of the shim. It flows into the reservoir chamber 27.

  The shim may be a plate-like member, for example, a metal washer. The shim is fixed between the end face 22f on the other end side of the plate 22 and the end face 10a of the plunger 10.

  6 and 7 show a third embodiment of the present invention. In the third embodiment, a spiral groove 23 is formed on an end surface 21e on one end side of a valve seat 21 of a check valve 20. In addition, a shim 24 made of a plate-like member is arranged between the valve seat 21 and the end face 10a of the plunger 10. The same member as the shim of the second embodiment can be used for the shim 24.

  The spiral groove 23 is a groove in which the plunger 10 side is opened. A helical orifice passage A in which the space in the groove is closed by the end surface 24b on the other end side of the shim 24 facing in the axial direction, and only the inlet 23a on the outer diameter side and the outlet 23b on the inner diameter side are open. Is configured. The entrance 23a of the spiral groove 23 faces the notch 21c at the outermost portion of the spiral. The outlet 23b of the spiral groove 23 faces the valve hole 21a at the smallest diameter portion of the spiral. The oil flowing out of the outlet 23b of the spiral groove 23 through the notch 21c and the orifice passage A flows into the reservoir chamber 27 through the valve hole 21a of the valve seat 21.

  FIG. 8 shows a fourth embodiment of the present invention. In the fourth embodiment, as in the third embodiment, a spiral groove 23 is formed in an end surface 21e on one end side of a valve seat 21 of a check valve 20. An orifice passage A is formed between the spiral groove 23 and the end face 10a of the plunger 10. The same member as that of the third embodiment shown in FIG. 7 can be used for the valve seat 21.

  The spiral groove 23 is a groove in which the plunger 10 side is opened. A spiral orifice passage in which the space in the groove is closed by an end face 10a facing the other end of the plunger 10 facing in the axial direction, and only the inlet 23a on the outer diameter side and the outlet 23b on the inner diameter side are open. Construct A. The inlet 23a of the spiral groove 23 (see FIG. 7) faces the notch 21c at the outermost portion of the spiral. The outlet 23b of the spiral groove 23 faces the valve hole 21a at the smallest diameter portion of the spiral. The oil flowing out of the outlet 23b of the spiral groove 23 through the notch 21c and the orifice passage A flows into the reservoir chamber 27 through the valve hole 21a of the valve seat 21.

  In the fourth embodiment, since other members such as the plate 22 and the shim 24 are not interposed between the valve seat 21 and the plunger 10, the number of parts is small and the cost can be reduced.

  In addition, in the fourth embodiment, as shown in FIG. 8, the reservoir chamber 27 has a smaller diameter and a shorter overall length in the axial direction than those of the other embodiments. Thus, the capacity of the reservoir chamber 27 can be set freely according to the specifications of the chain tensioner 1.

  In each of the above embodiments, the communication passage 30 and the oil supply passage 31 are arranged at one end of the oil supply space 28. However, the positions of the communication passage 30 and the oil supply passage 31 can be freely set according to the specifications of the chain tensioner 1. For example, the communication passage 30 and the oil supply passage 31 can be set at the other end of the oil supply space 28 or in the axial direction. It may be located at the center or the like.

  The embodiments disclosed this time are to be considered in all respects as illustrative 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 10a End face 18 Pressure chamber 20 Check valve 21 Valve seat 21a Valve hole 21c Notch 21e One end face 22 Plate 22e The other end face 23 Spiral groove 24b The other end face 25 Valve Body (check ball)
28 oil supply space 30 communication passage 31 oil supply passage 33 return spring 35 step A orifice passage

Claims (7)

A cylindrical cylinder (9) having one end open and the other end closed;
A cylindrical plunger (10) which is slidably supported in the axial direction on the inner periphery of the cylinder (9) and has an open end inserted into the cylinder (9) and a closed end protruding from the cylinder (9); When,
A return spring (33) for urging the plunger (10) in a direction protruding from the cylinder (9);
A pressure chamber (18) formed in the cylinder (9) so that the volume changes with the axial movement of the plunger (10);
A valve seat (21) provided at a lower end of the cylinder (9); and a valve body (25) for opening and closing a valve hole (21a) of the valve seat (21). A check valve (20) for allowing only oil flow from the inside to the pressure chamber (18);
A leak gap formed between the outer circumference of the plunger (10) and the inner circumference of the cylinder (9) and leaking oil from the pressure chamber (18) when the volume of the pressure chamber (18) is reduced;
An oil supply passage (31) for introducing oil from the outside to the inside of the cylinder (9),
A communication path (30) for communicating the leak gap with the inside of the plunger (10);
With
A notch (21c) is formed in the outer periphery of the valve seat (21), and an orifice passage (A) is formed in the valve seat (21) or a member arranged between the valve seat (21) and the plunger (10). Spiral groove (23) is formed,
When the pressure in the pressure chamber (18) becomes higher than the pressure in the plunger (10), the oil in the pressure chamber (18) passes through the notch (21c) and the orifice passage and the plunger. The chain tensioner flowing into the inside of (10). The member disposed between the valve seat (21) and the plunger (10) is a plate (22);
The spiral groove (23) is formed in the end surface (22e) on the other end side of the plate (22), and the spiral groove (23) and the end surface on the one end side of the valve seat (21) ( 21. The chain tensioner according to claim 1, wherein the orifice passage (A) is formed with the chain tensioner (21e).   The spiral groove (23) is formed on the end surface (21e) on the one end side of the valve seat (21), and the spiral groove (23), the valve seat (21), and the plunger (10) are formed. 2. The chain tensioner according to claim 1, wherein the orifice passage (A) is formed between the end face (24 b) of the member disposed between the orifice and the other end.   The spiral groove (23) is formed on the end face (21e) on the one end side of the valve seat (21), and is formed between the spiral groove (23) and the end face (10a) of the plunger (10). The chain tensioner according to claim 1, wherein the orifice passage (A) is formed by the following.   The amount of oil flowing out of the pressure chamber (18) by the orifice passage (A) is set to be larger than the amount of oil flowing out of the pressure chamber (18) by the leak gap. Item 5. The chain tensioner according to any one of items 1 to 4.   The chain according to any one of claims 1 to 5, wherein an oil supply space (28) communicating with the leak gap is formed between an outer periphery of the plunger (10) and an inner periphery of the cylinder (9). Tensioner.   The oil supply space (28) is formed on the entire outer periphery of the plunger (10), and a step (35) connected to the leak gap is provided at the other end of the oil supply space (28). The chain tensioner according to claim 6, wherein the chain tensioner is formed.

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