JP2023003976A - chain tensioner - Google Patents

Abstract

To prevent working fluid for a chain tensioner from leaking from an interval between a stepped hole accommodating a relief valve and a male screw member.SOLUTION: A chain tensioner includes an elastic body 48 for hermetically sealing an interval between a stepped hole 34 of a cylinder 9 and a male screw member 44. An O-ring or the like for hermetically sealing the interval between the male screw member and the stepped hole at a position nearer to a valve seat 39 in a screw axial line direction than a male screw portion 45 of the male screw member 44 and a female screw portion 42 of the stepped hole 34 is adopted as the elastic body 48.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain tensioner that maintains a constant tension of a chain for driving an engine camshaft, and more particularly to a chain tensioner that absorbs fluctuations in chain tension with a hydraulic damper.

An automobile engine generally transmits the rotation of a crankshaft to a camshaft via a timing chain (hereinafter referred to as "chain"), and the rotation of the camshaft opens and closes valves in a combustion chamber. In order to keep the tension of the chain within an appropriate range, a tension adjusting device is used which consists of a chain guide that is swingable about a fulcrum shaft and a chain tensioner that presses the chain through the chain guide.

A chain tensioner provided in the tension adjusting device includes a cylinder, a plunger slidably inserted inside the cylinder, a return spring that biases the plunger in the direction of protruding from the cylinder, and a chain tensioner formed behind the plunger in the cylinder. a pressure chamber, an oil supply passage for introducing hydraulic oil into the pressure chamber, and a check valve that allows only the flow of hydraulic oil from the oil supply passage side to the pressure chamber side is arranged in the oil supply passage It has been known.

In the case of this type of hydraulic chain tensioner, when the tension of the chain increases during engine operation, the tension of the chain moves the plunger in the direction in which it is pushed into the cylinder (hereinafter referred to as the "pushing direction"). Absorb tension. At this time, the hydraulic fluid in the pressure chamber flows out of the pressure chamber through the leak gap between the sliding surfaces of the plunger and the cylinder, and the viscous resistance of the hydraulic fluid produces a damping action, so 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 to close the pressure chamber, thereby ensuring damper action. On the other hand, when the tension of the chain becomes small during engine operation, the biasing force of the return spring causes the plunger to move in the direction in which it protrudes from the cylinder (hereinafter referred to as the "protrusion direction") to absorb slack in the chain. At this time, the check valve opens and the hydraulic oil flows into the pressure chamber from the oil supply passage, so that the plunger moves quickly. Hydraulic oil is supplied from the engine. Therefore, when the engine is stopped, the supply of hydraulic oil stops, the hydraulic damper cannot be generated, and the chain tensioner is pushed. To prevent this, a mechanism (no-back mechanism) is employed to prevent the plunger from being pushed in beyond a certain amount. Also, a relief valve is provided to prevent the chain from becoming over-tensioned when the chain is suddenly tensed. The relief valve has a valve body, a valve spring that biases the valve body in a valve closing direction, and a valve seat that receives the biased valve body. When the pressure in the pressure chamber exceeds the set pressure of the relief valve, the relief valve is opened and the pressure escapes from the pressure chamber to the outside of the cylinder.

Hydraulic chain tensioners of this type include an internal type in which the cylinder is bolted to the engine block, and an external type in which the flange portion of the cylinder is bolted to the outside of the engine cover.

Conventionally, in an exterior type chain tensioner, the cylinder is inserted into a tensioner mounting hole in an engine cover. A stepped hole is formed from the flange toward the inside of the cylinder, and the relief valve is accommodated in the stepped hole. By screwing the male threaded member into the female threaded portion of the stepped hole, the relief valve is tightened between the male threaded member and the stepped portion of the stepped hole. When the relief valve is opened, hydraulic fluid that has flowed out of the relief valve returns to the oil passage on the side of the engine cover. A gasket is sandwiched between the engine cover and the flange to prevent hydraulic oil from leaking from there. Also, a sealing adhesive is applied to the male threaded portion of the male threaded member. This sealing adhesive is for preventing hydraulic oil from leaking from the thread gap between the female threaded portion of the stepped hole and the male threaded portion of the male threaded member (for example, Patent Document 1).

JP 2007-333095 A

However, since the sealing adhesive applied to the male threaded portion of the male threaded member becomes larger than the aforementioned thread gap, when screwing into the stepped hole, the sealing adhesive cannot fully enter the thread gap, and the overflowing sealing adhesive is applied to the flange portion. accumulate on the side. At that time, if there is a portion that is not filled with the sealing adhesive in the screw gap, a minute gap will be formed, and there is a concern that hydraulic oil will leak outside from the screw gap due to the pressure when the relief valve is opened.

Therefore, the problem to be solved by the present invention is to prevent the hydraulic oil of the chain tensioner from leaking from between the stepped hole accommodating the relief valve and the male thread member.

In order to achieve the above object, the present invention provides a cylinder, a plunger slidably inserted into the cylinder, a return spring that biases the plunger in a direction of protruding from the cylinder, and a an arranged check valve, an oil supply passage for introducing working oil into a pressure chamber formed between the check valve and the plunger, and an oil drain passage for discharging the working oil from the pressure chamber to the outside of the cylinder; and a relief valve for opening and closing the drain oil passage, wherein the relief valve comprises a valve body, a valve spring for biasing the valve body in a valve closing direction, and a valve seat for receiving the biased valve body. and the cylinder has a stepped hole for accommodating the relief valve, and the stepped hole defines a female threaded portion and a stepped portion facing the valve seat in the thread axis direction of the female threaded portion. The oil drain passage communicates with the outside of the cylinder via the stepped hole from the pressure chamber, and the relief valve connects the male threaded portion of the male threaded member to the female threaded portion from the outside of the cylinder. an elastic body that seals between the male threaded member and the stepped hole at a position closer to the valve seat in the screw axis direction than the male threaded portion and the female threaded portion in the chain tensioner fixed by screwing into the chain tensioner is adopted.

According to the above configuration, when the relief valve is in the open state, hydraulic oil flows to the outside of the cylinder through the valve hole of the valve seat. At this time, part of the hydraulic oil that has flowed out from the relief valve passes between the relief valve and the stepped hole toward the male threaded member, but is closer to the valve seat in the screw axis direction than the male threaded portion and the female threaded portion. Since there is an elastic body that seals between the externally threaded member and the stepped hole at the position, hydraulic oil can be prevented from leaking from between the stepped hole and the externally threaded member. This is because when the male threaded member is screwed in, the contact state between the elastic body, the male threaded member, and the stepped hole is ensured by the pressure from the male threaded member in a stable bonding state on the surface. Thus, it is possible to prevent hydraulic oil from leaking from the chain tensioner through the threaded clearance between the stepped hole accommodating the relief valve and the male threaded member.

Specifically, the relief valve has an end face that contacts the male threaded member, and an outer peripheral end portion that increases in outer diameter as the distance from the male threaded member increases in the direction of the screw axis from the end face, and the male threaded member has a tightening surface that contacts the end surface of the relief valve, and a sealing surface that contacts the elastic body at a position closer to the male threaded portion in the screw axis direction than the tightening surface, and seals the male threaded member. The surface is a flat surface along the direction perpendicular to the screw axis, and the elastic body pressed from the sealing surface of the male screw member is pressed between the sealing surface and the outer peripheral edge of the relief valve. , and the stepped hole. In this way, when the male threaded member is screwed in, the tightening surface presses the relief valve toward the stepped portion of the stepped hole and fixes it, and the seal surface presses the elastic body, so that the outer peripheral edge of the relief valve presses the elastic body. The inner diameter side of the elastic body can be pushed between the outer peripheral end and the stepped hole while guiding the inner diameter side of the elastic body. As a result, the pressed elastic body is stably brought into close contact with the sealing surface of the male screw member, the outer peripheral edge of the relief valve, and the stepped hole. In addition, since the sealing surface of the male threaded member is a flat surface along the direction perpendicular to the screw axis, the sealing surface of the male threaded member strongly presses the elastic body against the outer peripheral edge of the relief valve, thereby It can be brought into close contact with the stepped hole. In addition, by adopting a seal surface that contacts the elastic body at a position closer to the male threaded portion than the tightening surface of the male screw member, the seal surface can be kept away from the relief valve and a space for arranging the elastic body can be formed. .

Further, the stepped hole has a stepped seal seat portion facing the end surface of the male thread member in the thread line direction at a position closer to the step portion side than the female thread portion in the thread axis direction. Preferably, the elastic body pressed against the end face of the male screw member is in close contact with the end face and the seal seat portion of the stepped hole. With this arrangement, the gap between the male threaded member and the stepped hole can be sealed only by pressing the elastic body in the axial direction of the screw between the seal seat portion of the stepped hole and the end face of the male threaded member, and the elastic body acts as a relief valve. It is no longer necessary to adhere to the

In addition, the relief valve has an end face that contacts the male threaded member, and an outer peripheral end portion that increases in outer diameter as the distance from the male threaded member increases in the direction of the screw axis from the end face, and the male threaded member The sealing surface of the male screw member has a tightening surface that contacts the end surface of the relief valve and a tapered sealing surface that increases in diameter from the tightening surface toward the male threaded portion in the axial direction of the screw. Preferably, the elastic body pressed from the sealing surface is in close contact with the sealing surface, the outer peripheral edge of the relief valve, and the stepped hole. In this way, when the male screw member is screwed in, the tightening surface presses the relief valve toward the stepped portion of the stepped hole and fixes it, the sealing surface presses the elastic body, and the outer peripheral edge of the relief valve is elastic. While guiding the inner diameter side of the body, the body can be pressed between the outer peripheral end and the stepped hole to apply pressure to the elastic body. As a result, the pressed elastic body is stably brought into close contact with the sealing surface of the male screw member, the outer peripheral edge of the relief valve, and the stepped hole. In addition, since the sealing surface of the male threaded member is tapered as described above, it is easy to push the elastic body between the outer peripheral edge of the relief valve and the stepped hole while enlarging the inner diameter of the elastic body with the sealing surface of the male threaded member. become. In addition, since the sealing surface of the male screw member has a tapered shape in which the diameter increases from the tightening surface toward the male screw portion, it is possible to move the sealing surface away from the relief valve and form a space for arranging the elastic body. can.

The seal retainer sandwiched between the male threaded member and the relief valve is further provided, the relief valve has an end surface that contacts the seal retainer, and the male threaded member has a tightening surface that contacts the seal retainer. and a seal surface that contacts the elastic body at a position closer to the male threaded portion in the screw axis direction than the tightening surface, and the seal retainer is provided between the relief valve and the inner circumference of the stepped hole. The stepped hole protrudes toward the inner periphery of the stepped hole so as to face the gap between them in the thread axial direction and also face the sealing surface of the male thread member in the thread axial direction, and is pressed from the sealing surface of the male thread member. Preferably, the elastic body is in close contact with the seal surface, the seal retainer, and the stepped hole. In this way, by screwing in the male threaded member, the tightening surface of the seal retainer is sandwiched between the seal retainer and the relief valve, and the relief valve is pressed toward the stepped portion of the stepped hole to be fixed. can be pressed against the seal retainer and pressed against the elastomer. As a result, the pressed elastic body is stably brought into close contact with the sealing surface of the male screw member, the seal retainer and the stepped hole. In addition, the seal retainer faces the gap between the relief valve and the inner circumference of the stepped hole in the axial direction of the screw, and also faces the seal surface of the male screw member in the axial direction of the screw. Since it protrudes toward the elastic body, it is possible to increase the contact area between the sealing surface, the stepped hole, the seal retainer, and the elastic body by applying strong pressure to the elastic body, thereby improving the sealing performance. In addition, by adopting a seal surface that contacts the elastic body at a position closer to the male threaded portion than the tightening surface of the male screw member, the seal surface can be kept away from the relief valve and a space for arranging the elastic body can be formed. .

The elastic body is preferably an O-ring. When an O-ring is used as the elastic body, the elastic body pressed from the sealing surface of the male screw member is easily compressed by following the surface shape of the contacting partner against any contacting partner. It becomes easy to secure the contact area.

Further, it is preferable that a sealing adhesive is applied to the male threaded portion of the male threaded member. In this way, the sealing adhesive can prevent loosening of the male thread member. Since the elastic body seals the hydraulic oil upstream of the screw gap, even if the seal adhesive is incomplete, there is no concern that the hydraulic oil will leak out of the cylinder. is not asked. In the present invention, the use of the seal adhesive can be arbitrarily selected.

A flange portion is formed on the outside of the cylinder, the stepped hole is formed from the flange portion toward the inside of the cylinder, the cylinder is inserted into a tensioner mounting hole of an engine cover, and the The flange portion may be bolted to the outside of the engine cover. In this way, since the hydraulic oil of the chain tensioner bolted to the engine cover at the flange portion does not leak from between the male thread member and the flange portion, oil contamination of the engine cover can be prevented even if the leak inspection process is omitted. can.

As described above, the present invention can prevent hydraulic oil from leaking from between the stepped hole accommodating the relief valve and the male screw member by adopting the above configuration.

1 is a sectional view showing a chain tensioner according to a first embodiment of the invention; FIG. 2 is a front view showing a chain transmission provided with the chain tensioner of FIG. 1; Enlarged view of the vicinity of the relief valve in Fig. 1 FIG. 2 is an enlarged view of the stepped hole in FIG. Sectional drawing which shows relief valve vicinity which concerns on 2nd embodiment of this invention Sectional drawing which shows relief valve vicinity which concerns on 3rd embodiment of this invention Sectional drawing which shows relief valve vicinity which concerns on 4th embodiment of this invention Enlarged view of the vicinity of the elastic body in FIG.

A first embodiment as an example of the invention will be described with reference to FIGS. 1 to 4. FIG.

A chain tensioner 1 according to the embodiment shown in FIG. 1 is provided in a chain transmission shown in FIG. In this chain transmission device, 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 drives the rotation of the crankshaft 2. It 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 which is supported so as to be able to swing around a fulcrum shaft 7 . Chain tensioner 1 presses chain 6 via its chain guide 8 .

As shown in FIG. 1, the chain tensioner 1 includes a tubular cylinder 9 with one end closed and the other open, and a plunger 10 inserted axially slidably into the cylinder 9 . The cylinder 9 has an inner wall surface 11 along an imaginary cylindrical surface. Here, "axial direction" refers to a direction along the center line of the imaginary cylindrical surface.

A flange portion 12 is formed outside the cylinder 9 . The flange portion 12 has an abutment surface 13 extending in a direction perpendicular to the axial direction. As shown in FIG. 2, the cylinder 9 is inserted into the tensioner mounting hole 15 of the engine cover 14 with the open end facing inside the engine cover 14 . The flange portion 12 is fixed to the outside (outer surface) of the engine cover 14 with bolts 16 . A gasket 17 is sandwiched between the abutment surface 13 of the flange portion 12 and the outer surface of the engine cover 14 to prevent leakage of hydraulic oil.

As shown in FIG. 1, a check valve 18 is incorporated in the cylinder 9 and a pressure chamber 19 is formed between the check valve 18 and the plunger 10 . Further, the cylinder 9 is formed with an oil supply passage 20 through which hydraulic oil is introduced into the pressure chamber 19 via the check valve 18 .

The oil supply passage 20 extends from an oil introduction hole 21 for introducing hydraulic oil from outside the cylinder 9 and a reservoir chamber 22 connected to the downstream side of the oil introduction hole 21 and formed adjacent to the upstream side of the check valve 18. Become. A reservoir chamber 22 is formed between the check valve 18 and the closed end of the cylinder 9 . An oil introducing hole 21 is opened in the reservoir chamber 22 . An inlet (not shown) of the oil introduction hole 21 opens to the abutment surface 13 of the flange portion 12 and communicates with an oil passage on the side of the engine cover 14 (see FIG. 2). Hydraulic oil supplied from an oil pump (not shown) is introduced into pressure chamber 19 through oil introduction hole 21, reservoir chamber 22, and check valve 18 shown in FIG.

The check valve 18 has a seat 23 , a ball 24 and a retainer 25 . The seat 23 has a cylindrical shape having a valve hole in the center that communicates between the oil supply passage 20 and the pressure chamber 19 . The seat 23 is press-fitted into the cylinder 9 and fixed. The seat 23 has a tapered seat surface at the end of the valve hole on the pressure chamber 19 side. The ball 24 is provided movably between a valve closing position in contact with the seat surface of the seat 23 and a valve opening position away from the seat surface. Hydraulic oil is permitted to flow from the oil supply passage 20 side to the pressure chamber 19 side, but is prohibited from flowing from the pressure chamber 19 side to the oil supply passage 20 side.

The plunger 10 is formed in a bottomed tubular shape with an open end for insertion into the cylinder 9 . A small leak gap 26 is formed between the outer peripheral surface of the plunger 10 and the fitting surface of the inner wall surface 11 of the cylinder 9 . When the plunger 10 moves in the direction of being pushed into the cylinder 9 , the working oil in the pressure chamber 19 flows out of the cylinder 9 from the open end of the cylinder 9 through the leak gap 26 .

A female thread 27 is formed on the inner periphery of the portion of the plunger 10 inserted into the cylinder 9 . A screw rod 29 having an external thread 28 corresponding to the internal thread 27 is incorporated in the plunger 10 . One end of the screw rod 29 protrudes from the plunger 10 and the protruding end is in contact with the seat 23 . The male thread 28 and the female thread 27 are formed in a serrated shape such that the flank angle of the pressure side flank that receives pressure when a load is applied in the direction of pushing the plunger 10 into the cylinder 9 is larger than the flank angle of the play side flank. there is Such male thread 28 and female thread 27 may be, for example, a pressure side flank having a flank angle of 65° and a play side flank having a flank angle of 7°, or a pressure side flank having a flank angle of 75° and a play side A flank having a flank angle of 15° can be employed. Moreover, between the male thread 28 and the female thread 27, there is provided an axial play of about 1 mm or less.

A return spring 30 is incorporated between the plunger 10 and the screw rod 29 . The return spring 30 has one end supported by the screw rod 29 and the other end pressing the plunger 10 via a spring seat 31 . Due to this pressure, the plunger 10 is urged in the direction of protruding from the cylinder 9 . The protruding end of the plunger 10 from the cylinder 9 contacts the chain guide 8 as shown in FIG.

As shown in FIGS. 1 and 3 , the chain tensioner 1 includes an oil discharge passage 32 for releasing hydraulic oil from the pressure chamber 19 to the outside of the cylinder 9 and a relief valve 33 for opening and closing the oil discharge passage 32 .

The oil drain passage 32 is composed of a stepped hole 34 formed from the flange portion 12 toward the inside of the cylinder 9 and an outlet passage 35 branched from the stepped hole 34 . The outlet passage 35 communicates with the oil passage on the engine cover 14 side.

The relief valve 33 includes a valve body 36, a valve spring 37 that biases the valve body 36 in the valve closing direction, a valve retainer 38 that receives the valve spring 37, and a valve seat 39 that receives the biased valve body 36. have. The valve seat 39 has a valve hole and a seat surface on which the valve body 36 is seated. The valve seat 39 and the valve retainer 38 are fitted together to form a valve case that accommodates the valve element 36 and the valve spring 37 . The valve body 37 is provided movably between a valve closing position (position shown) in which it contacts the seat surface of the valve seat 39 and a valve opening position in which it separates from the seat surface of the valve seat 39 . An air vent groove recessed from the seat surface of the valve seat 39 may be formed.

The stepped hole 34 communicates between the outer peripheral surface of the flange portion 12 and the pressure chamber 19, and has a shape with a larger hole diameter on the outer peripheral surface side of the flange portion 12 and a smaller hole diameter on the pressure chamber 19 side. . A relief valve 33 is accommodated in the large-diameter portion of the stepped hole 34 .

A small diameter hole portion of the stepped hole 34 communicates with a valve hole of the valve seat 39 and opens to the pressure chamber 19 . The exit path 35 communicates from the inner periphery of the large diameter hole portion of the stepped hole 34 to the abutment surface 13 . A plurality of outflow ports 40 of the relief valve 33 are formed in the valve retainer 38 . A gap 41 is provided between the outflow port 40 and the outlet passage 35 .

The oil drain passage 32 communicates with the outside of the cylinder 9 from the pressure chamber 19 via the small diameter portion of the stepped hole 34, the inside of the relief valve 33, the gap 41, and the outlet passage 35 in this order. When the pressure in the pressure chamber 19 exceeds a preset pressure, the valve body 36 separates from the seat surface of the valve seat 39, and the relief valve 33 is in an open state in which the oil drain passage 32 is opened. The oil is released from the pressure chamber 19 to the outside of the cylinder 9.

The stepped hole 34 has a female threaded portion 42 formed in the large-diameter hole portion thereof, and a stepped portion 43 facing the valve seat 39 in the direction of the screw axis of the female threaded portion 42 . The relief valve 33 is fixed by screwing the male threaded portion 45 of the male threaded member 44 into the female threaded portion 42 of the stepped hole 34 .

As shown in FIG. 4 , a sealing adhesive 46 is interposed in the screw gap between the male threaded portion 45 and the female threaded portion 42 . The sealing adhesive 46 has a main purpose of preventing loosening of the male screw member 44, and has an auxiliary purpose of closing screw clearances. As the sealing adhesive 46, an appropriate material such as an acrylic resin may be adopted.

With the sealing adhesive 46 applied to the male threaded portion 45 of the male threaded member 44, when a screwdriver (not shown) is connected to the hexagonal hole 47 of the male threaded member 44 and the male threaded portion 45 is screwed into the female threaded portion 42, A sealing adhesive 46 is fed between the male threaded portion 45 and the female threaded portion 42 as shown in FIG. At this time, since the viscous sealing adhesive 46 is applied in a larger amount than the screw gap, it does not enter the screw gap completely and overflows and accumulates on the outer periphery of the flange portion 12, creating a minute gap. Remaining incomplete fill may occur. If the sealing adhesive 46 alone seals between the stepped bore 34 and the externally threaded member 44, incomplete filling cannot be tolerated. This is because when the hydraulic oil flows through the gap 41 between the relief valve 33 and the outlet passage 35 shown in FIG. In particular, in the case of an engine cover for a two-wheeled vehicle, it is required to reliably prevent leaked hydraulic oil from falling on the road surface because it causes tires to slip. Leak testing can confirm proper filling of the sealing adhesive, but the process is labor intensive.

Therefore, in this chain tensioner 1, as shown in FIGS. 1 and 3, the male threaded member 44 and the stepped hole 34 are located closer to the valve seat 39 side than the male threaded portion 45 and the female threaded portion 42 in the screw axis direction. An elastic body 48 is provided to seal the gap.

The elastic body 48 consists of an O-ring. Further, the elastic body is not limited to the O-ring, and may be a washer-shaped elastic body or the like, or a liquid gasket.

The relief valve 33 has an end face 49 in contact with the male threaded member 44 and an outer peripheral end portion 50 whose outer diameter increases with distance from the male threaded member 44 in the direction of the screw axis from the end face 49 .

An end face 49 of the relief valve 33 is formed in the valve retainer 38 . This end face 49 is flat in a direction perpendicular to the direction of the screw axis. An outer peripheral end portion 50 of the relief valve 33 is formed in an R-chamfered shape on the outer periphery of the valve retainer 38 . The purpose of forming the outer peripheral end portion 50 on the relief valve 33 is to press the inner diameter side of the elastic body 48 to guide the elastic body 48 between the relief valve 33 and the stepped hole 34 . The purpose of forming the outer peripheral end portion 50 on the valve retainer 38 is to relieve stress concentration when the valve retainer 38 is press-formed into a cylindrical shape with a bottom.

The male threaded member 44 has a tightening surface 51 that contacts the end face 49 of the relief valve 33 and a seal surface 52 that contacts the elastic body 48 at a position closer to the male threaded portion 45 than the tightening surface 51 in the screw axis direction.

The tightening surface 51 of the male screw member 44 is a portion that presses the end surface 49 of the relief valve 33 in the direction of the screw axis. The tightening surface 51 is a flat surface extending in a direction perpendicular to the screw axis direction, and is provided with a smaller diameter than the end surface 49 of the relief valve 33 . A seal surface 52 of the male screw member 44 is flat in a direction perpendicular to the screw axis and has a larger diameter than the outer peripheral end portion 50 of the relief valve 33 .

The accommodation of the relief valve 33 in the stepped hole 34 and the placement of the elastic body 48 can be performed in the same step. That is, the valve seat 39 of the relief valve 33 is placed on the stepped portion 43 of the stepped hole 34 , the inner diameter side of the elastic body 48 contacts the outer peripheral end portion 50 of the relief valve 33 , and the elastic body 48 contacts the inner periphery of the stepped hole 34 . The elastic body 48 is arranged between the outer peripheral end portion 50 and the stepped hole 34 so that the outer diameter side of the body 48 is in contact (see the dashed line in FIG. 3). It is screwed into the female screw portion 42 . The tightening surface 51 of the male screw member 44 to be screwed in pushes the end face 49 of the relief valve 33 in the direction of the screw axis, so that the relief valve 33 can be pressed against the stepped portion 43 of the stepped hole 34 in the direction of the screw axis. At this time, the elastic member 48 is pushed by the sealing surface 52 of the screwed male screw member 44, and the outer peripheral end portion 50 of the relief valve 33 and the cylindrical surface portion 53 between the female screw portion 42 of the stepped hole 34 and the outlet passage 35 are pushed. The elastic body 48 can be pressed between the sealing surface 52 , the outer peripheral end portion 50 and the cylindrical surface portion 53 so as to be in close contact with the sealing surface 52 . When the tightening torque for screwing the male threaded member 44 reaches a predetermined value, the elastic body 48 is brought into contact with a predetermined sealing performance as depicted by the solid line in FIG. The elastic body 48 pressed from 52, the seal surface 52, the outer peripheral end portion 50 of the relief valve 33, and the cylindrical surface portion 53 of the stepped hole 34 can be brought into a stable contact state. , the relief valve 33 can be fixed.

The height difference and diameter difference between the tightening surface 51 and the sealing surface 52 in the direction of the thread axis can be adjusted by adjusting the elastic body 48 as shown in FIG. It is set so that it can be arranged in the compressed state drawn by the solid line.

In addition, the elastic body 48 can bring the contact area in close contact with the corresponding contact partner (the seal surface 52, the outer peripheral end portion 50, and the cylindrical surface portion 53) into a stable surface contact state by screwing the male screw member 44. It is not limited to the O-ring described above as long as it has elasticity at least at the contact portion.

An operation example of the chain tensioner 1 will be described (see FIGS. 1 and 2).

When the tension of the chain 6 increases during engine operation, the tension of the chain 6 moves the plunger 10 in the pushing direction to absorb the tension of the chain 6.例文帳に追加At this time, a damping force is generated by the viscous resistance of the hydraulic oil flowing out of the pressure chamber 19 through the leak gap 26 , and the screw rod 29 is axially displaced between the female thread 27 and the male thread 28 by the vibration of the chain 6 . The plunger 10 moves slowly because it rotates with respect to the plunger 10 while repeating advance and retreat within the range of the gap.

On the other hand, when the tension of the chain 6 becomes small during engine operation, the plunger 10 moves in the protruding direction due to the biasing force of the return spring 30 to absorb the slackness of the chain 6 . At this time, the check valve 18 opens and the hydraulic oil flows into the pressure chamber 19 from the oil supply passage 20, so that the plunger 10 moves quickly.

When the engine is stopped, the tension in the chain 6 may increase depending on the position where the camshaft 4 is stopped. 10 positions are fixed. Therefore, when the engine is restarted, the chain 6 is less likely to become slack, and the engine can be started smoothly.

Further, when the engine stops, the oil pump that supplies hydraulic oil to the oil supply passage 20 also stops. At this time, the hydraulic fluid in the reservoir chamber 22 is held by the check valve 18 , and the hydraulic fluid in the reservoir chamber 22 can be prevented from flowing out to the pressure chamber 19 . Therefore, when the engine is restarted, the hydraulic fluid in the reservoir chamber 22 flows into the pressure chamber 19, and the pressure chamber 19 is quickly filled with hydraulic fluid. As a result, it is possible to suppress the deterioration of the damper action immediately after restarting the engine.

Further, when the engine resonates and the tension of the chain 6 suddenly increases, the relief valve 33 opens to release the pressure in the pressure chamber 19, thereby preventing the chain 6 from being overstretched.

The chain tensioner 1 is as described above (see FIGS. 1 and 3), and when the relief valve 33 is opened, hydraulic oil enters the relief valve 33 through the valve hole of the valve seat 39 and flows out through the outlet. 40 , the gap 41 and the outlet passage 35 to the outside of the cylinder 9 . At this time, part of the hydraulic oil that has flowed out from the outlet 40 of the relief valve 33 into the gap 41 flows from the gap 41 toward the male threaded member 44 , but the valve seat 39 is pushed further along the screw axis than the male threaded portion 45 and the female threaded portion 42 . There is a resilient body 48 that seals between the male threaded member 44 and the stepped bore 34 at a lateral position. Here, when the male screw member 44 is screwed, the contact state between the elastic body 48 and the sealing surface 52, the contact state between the elastic body 48 and the outer peripheral end portion 50 of the relief valve 33, and the contact state between the elastic body 48 and the stepped hole 34 are shown. The state is ensured in a stable contact state on the surface by pressing from the male screw member 44 respectively. Therefore, this chain tensioner 1 can prevent hydraulic oil from leaking from the threaded clearance between the stepped hole 34 accommodating the relief valve 33 and the male threaded member 44 .

The chain tensioner 1 (see FIG. 3) has an end face 49 where the relief valve 33 contacts the male threaded member 44, and an outer peripheral end portion whose outer diameter increases as the distance from the male threaded member 44 increases from the end face 49 in the direction of the screw axis. 50, the male screw member 44 has a tightening surface 51 that contacts the end surface 49 of the relief valve 33, and a seal surface that contacts the elastic body 48 at a position closer to the male screw portion 45 in the screw axis direction than the tightening surface 51. 52, and the elastic body 48 pressed from the sealing surface 52 of the male threaded member 44 is in close contact with the sealing surface 52, the outer peripheral end portion 50 of the relief valve 33, and the stepped hole 34. When the member 44 is screwed in, the tightening surface 51 pushes the relief valve 33 toward the stepped portion 43 of the stepped hole 34 to fix it, and the sealing surface 52 pushes the elastic body 48 to adjust the outer diameter of the relief valve 33 to the above-mentioned value. The elastic body 48 can be pressed between the outer peripheral end 50 and the stepped hole 34 while guiding the inner diameter side of the elastic body 48 with the changed outer peripheral end 50 . As a result, the pressed elastic body 48 is stably brought into close contact with the sealing surface 52 of the male screw member 44 , the outer peripheral end portion 50 of the relief valve 33 and the stepped hole 34 .

In addition, in this chain tensioner 1, since the sealing surface 52 of the male threaded member 44 is flat along the direction perpendicular to the screw axis, the sealing surface 52 of the male threaded member 44 presses the elastic body 48 against the relief valve 33. can be tightly pressed against the outer peripheral edge 50 of the outer peripheral edge 50 and the stepped hole 34 .

In addition, the chain tensioner 1 employs a seal surface 52 that contacts the elastic body 48 at a position closer to the male threaded portion 45 than the tightening surface 51 of the male threaded member 44, thereby keeping the seal surface 52 away from the relief valve 33. A space for arranging the elastic body 48 can be formed.

In addition, since the elastic body 48 of the chain tensioner 1 is made of an O-ring, the elastic body 48 pressed from the sealing surface 52 of the male thread member 44 can be applied to any contact partner (seal surface 52, outer peripheral edge 50, stepped Since the hole 34) is also easily compressed following the surface shape of the contact partner, it becomes easy to secure a contact area with any contact partner.

In addition, since the chain tensioner 1 has the sealing adhesive 46 applied to the male threaded portion 45 of the male threaded member 44 (see FIGS. 3 and 4), the sealing adhesive 46 can prevent the male threaded member 44 from loosening. can. Even if the sealing adhesive 46 is incompletely filled, the presence of the elastic body 48 prevents hydraulic oil from leaking out of the cylinder 9 from between the stepped hole 34 and the male screw member 44 . Therefore, the sealing performance of the sealing adhesive 46 is not an issue, and a leak inspection process for inspecting this sealing performance is unnecessary.

Further, the chain tensioner 1 has a flange portion 12 formed outside the cylinder 9 (see FIGS. 1 to 3), and a stepped hole 34 is formed from the flange portion 12 toward the inside of the cylinder 9. The cylinder 9 is inserted into the tensioner mounting hole 15 of the engine cover 14, and the flange portion 12 is bolted to the outside of the engine cover 14. Since the oil does not leak from the gap, the engine cover 14 can be prevented from being stained with oil even if the leak inspection process is omitted.

A second embodiment of the invention is shown in FIG. In addition, below, it stops at describing a difference with 1st embodiment.

A stepped hole 60 shown in FIG. 5 has a seal seat portion 61 at a position closer to the stepped portion 43 in the screw axis direction than the female thread portion 42 . The seal seat portion 61 enlarges the diameter of the stepped hole 60 at a position between the outlet passage 35 and the female thread portion 42 and is formed in a stepped shape facing the end surface 63 of the male thread member 62 in the thread line direction. The seal seat portion 61 and the end face 63 of the male screw member 62 are flat surfaces along the direction perpendicular to the screw axis direction. When the elastic body 64 is arranged on the seal seat portion 61 and the male threaded member 62 is screwed in, it is pressed against the end surface 63 of the male threaded member 62 in the direction of the screw axis and pressed against the seal seat portion 61 of the stepped hole 60 . Therefore, the elastic body 64 pressed against the end surface 63 of the male screw member 62 is in close contact with the end surface 63 and the seal seat portion 61 .

According to the second embodiment, the gap between the male threaded member 62 and the stepped hole 60 is sealed simply by pressing the elastic body 64 in the direction of the screw axis between the seal seat portion 61 of the stepped hole 60 and the end surface 63 of the male threaded member 62 . It becomes unnecessary to bring the elastic body 64 into close contact with the relief valve 33 .

The elastic body 64 consists of a gasket along a direction perpendicular to the screw axis direction. Such an elastic body 64 is preferable in that it can be brought into a state of surface contact by simple compression deformation of crushing between the facing end face 63 and the seal seat portion 61, but an O-ring, resin, or the like may be used instead of the gasket. is also possible.

The gasket is preferably made by punching a sheet such as a rubber sheet or a joint sheet into an annular shape. Since such an elastic body 64 is less likely to shrink in the direction of the screw axis than an O-ring, there is an advantage that the tightening torque of the male threaded member 62 is less likely to become unstable. The joint sheet is obtained by uniformly mixing rubber, polyamide fiber, glass fiber, expanded graphite, etc., and then press-rolling the mixture with heated rolls. Such a gasket is not limited to a soft gasket made of a single material, and may be a gasket sheet punched out of which a core material such as a joint sheet or thin metal plate is coated with a resin such as polytetrafluoroethylene (PTFE).

A third embodiment according to the invention is shown in FIG.

A male threaded member 70 according to the third embodiment has a tightening surface 71 and a tapered sealing surface 72 that increases in diameter from the tightening surface 71 toward the male threaded portion 45 in the axial direction of the screw. The elastic body 73 pressed from the sealing surface 72 of the male screw member 70 is in close contact with the sealing surface 72 , the outer peripheral edge 50 of the relief valve 33 , and the inner periphery of the stepped hole 34 .

According to the third embodiment, the elastic body 73 is arranged between the outer peripheral end portion 50 of the relief valve 33 and the stepped hole 34 (see one-dot chain line in the figure), and when the male threaded member 70 is screwed, the male threaded member 70 is Since the sealing surface 72 has a tapered shape in which the diameter increases from the tightening surface 71 toward the male threaded portion 45 in the direction of the screw axis, the outer peripheral end of the relief valve 33 is expanded while the inner diameter of the elastic body 73 is expanded by the sealing surface 72 . It becomes easy to push the elastic body 73 between the portion 50 and the stepped hole 34 .

Further, according to the third embodiment, since the sealing surface 72 of the male threaded member 70 is tapered with the diameter increasing from the tightening surface 71 toward the male threaded portion 45 side, the sealing surface 72 is moved away from the relief valve, A space for arranging the elastic body 73 can be formed.

A fourth embodiment according to the present invention is shown in FIGS. 7-8.

The fourth embodiment includes a seal retainer 81 sandwiched between the male threaded member 80 and the relief valve 33 . The seal retainer 81 is disc-shaped along a direction perpendicular to the screw axis. End face 49 of relief valve 33 contacts seal retainer 81 . A tightening surface 82 of the male threaded member 80 contacts the seal retainer 81 .

The diameter of the male threaded member 80 increases from the tightening surface 82 toward the male threaded portion 85 in the threaded axial direction so that it contacts the elastic body 83 at a position closer to the male threaded portion 85 in the threaded axial direction than the tightening surface 82 . has a tapered sealing surface 84 with an increased . Therefore, the sealing surface 84 can be kept away from the relief valve 33 and a space for arranging the elastic body 83 can be formed. In addition, the portion where the seal surface 84 is formed is closer to the male threaded portion 85 side by the thickness of the seal retainer 81 than in the third embodiment, and accordingly the male threaded portion 85 is shortened. .

The seal retainer 81 faces the gap 41 between the relief valve 33 and the inner circumference of the stepped hole 34 in the axial direction of the thread, and faces the sealing surface 84 of the male threaded member 80 in the axial direction of the thread. It protrudes toward the inner periphery of 34. The diameter of the seal retainer 81 is set equal to the outer diameter of the relief valve 33 . Therefore, the peripheral edge of the seal retainer 81 faces the cylindrical surface portion 53 of the stepped hole 34 with a fitting gap.

When the elastic body 83 is arranged between the seal retainer 81 and the stepped hole 34 and the male screw member 80 is screwed in, the tightening surface 82 of the elastic body 83 sandwiches the seal retainer 81 between the end surface 49 of the relief valve 33 and the relief valve. 33 is pushed toward the stepped portion 43 of the stepped hole 34 and fixed, and the elastic body 83 is pressed against the seal retainer 81 by the sealing surface 84 of the stepped hole 34 to press the elastic body. As a result, the elastic body 83 pressed from the sealing surface 84 of the male screw member 80 is in close contact with the sealing surface 84, the seal retainer 81, and the inner circumference of the stepped hole 34, as shown in FIG. Here, as in the third embodiment, the sealing surface 84 of the male screw member 80 is tapered and presses the elastic body 83 while enlarging the inner diameter of the elastic body 83 .

According to the fourth embodiment, the seal retainer 81 faces the gap 41 between the relief valve 33 and the inner circumference of the stepped hole 34 in the thread axis direction, and also faces the seal surface 84 of the male thread member 80 in the thread axis direction. , so that the elastic body 83 is strongly pressed against the outer peripheral edge 50 of the relief valve 33 to seal the relief valve 33. The contact area between the surface 84, the stepped hole 34, the seal retainer 81 and the elastic body 83 can be increased to improve the sealing performance.

In each of the above-described embodiments, the no-back mechanism is of a saw-teeth type using a screw rod, but other methods such as a registering method may be employed, or the no-back mechanism may be omitted. good too.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims.

1 Chain tensioner 9 Cylinder 10 Plunger 12 Flange 14 Engine cover 15 Tensioner mounting hole 18 Check valve 19 Pressure chamber 20 Oil supply passage 30 Return spring 32 Oil drain passage 33 Relief valve 34, 60 Stepped hole 36 Valve body 37 Valve spring 38 Valve Retainer 39 Valve seat 42 Female threaded portion 43 Stepped portions 44, 62, 70, 80 Male threaded members 45, 85 Male threaded portion 46 Seal adhesive 48, 64, 73, 83 Elastic body 49 Relief valve end surface 50 Relief valve outer peripheral end portion 51 , 71, 82 tightening surfaces 52, 72, 84 sealing surface 61 seal seat 63 end surface 81 of male thread member seal retainer

Claims (8)

a cylinder, a plunger slidably inserted into the cylinder, a return spring biasing the plunger in a direction of protruding from the cylinder, a check valve arranged in the cylinder, the check valve and the an oil supply passage that introduces hydraulic oil into a pressure chamber formed between the plunger and the plunger; an oil drain passage that releases the hydraulic oil from the pressure chamber to the outside of the cylinder; a relief valve that opens and closes the oil drain passage; with
The relief valve has a valve body, a valve spring that biases the valve body in a valve closing direction, and a valve seat that receives the biased valve body,
the cylinder has a stepped hole that accommodates the relief valve, the stepped hole has a female threaded portion and a stepped portion facing the valve seat in the threaded axial direction of the female threaded portion;
the oil drain passage communicates with the outside of the cylinder via the stepped hole from the pressure chamber,
In a chain tensioner in which the relief valve is fixed by screwing a male threaded portion of a male threaded member into the female threaded portion from outside the cylinder,
The chain tensioner further comprises an elastic body that seals between the male threaded member and the stepped hole at a position closer to the valve seat in the screw axis direction than the male threaded portion and the female threaded portion. The relief valve has an end face that contacts the male threaded member, and an outer peripheral end portion that increases in outer diameter as the distance from the male threaded member increases in the direction of the screw axis from the end face,
The male threaded member has a tightening surface that contacts the end face of the relief valve, and a seal surface that contacts the elastic body at a position closer to the male threaded portion in the screw axis direction than the tightening surface,
The sealing surface of the male screw member is a flat surface along a direction perpendicular to the screw axis,
2. The chain tensioner according to claim 1, wherein the elastic body pressed from the sealing surface of the male screw member is in intimate contact with the sealing surface, the outer peripheral edge of the relief valve, and the stepped hole. The stepped hole has a stepped seal seat facing the end surface of the male thread member in the thread direction at a position closer to the step side than the female thread in the thread axis direction,
2. The chain tensioner according to claim 1, wherein the elastic body pressed against the end face of the male screw member is in close contact with the end face and the seal seat portion of the stepped hole. The relief valve has an end face that contacts the male threaded member, and an outer peripheral end portion that increases in outer diameter as the distance from the male threaded member increases in the direction of the screw axis from the end face,
The male threaded member has a tightening surface that contacts the end surface of the relief valve, and a tapered sealing surface that increases in diameter from the tightening surface toward the male threaded portion in the axial direction of the screw,
2. The chain tensioner according to claim 1, wherein the elastic body pressed from the sealing surface of the male screw member is in intimate contact with the sealing surface, the outer peripheral edge of the relief valve, and the stepped hole. further comprising a seal retainer sandwiched between the male threaded member and the relief valve;
the relief valve has an end face that contacts the seal retainer;
The male threaded member has a tightening surface that contacts the seal retainer, and a seal surface that contacts the elastic body at a position closer to the male threaded portion in the screw axis direction than the tightening surface,
The seal retainer faces the gap between the relief valve and the inner circumference of the stepped hole in the axial direction of the thread, and also faces the sealing surface of the male thread member in the axial direction of the stepped hole. It protrudes toward the inner circumference,
2. The chain tensioner according to claim 1, wherein the elastic body pressed from the sealing surface of the male screw member is in intimate contact with the sealing surface, the seal retainer and the stepped hole. A chain tensioner according to any one of claims 1 to 5, wherein said elastic body comprises an O-ring. The chain tensioner according to any one of claims 1 to 6, wherein a sealing adhesive is applied to the male threaded portion of the male threaded member. A flange portion is formed on the outside of the cylinder, the stepped hole is formed from the flange portion toward the inside of the cylinder, the cylinder is inserted into a tensioner mounting hole of an engine cover, and the The chain tensioner according to any one of claims 1 to 7, wherein the flange portion is bolted to the outside of the engine cover.

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