JP5734576B2 - Rush adjuster - Google Patents

Description

The present invention also relates to a lash adjuster.

  Conventionally, a lash adjuster that automatically adjusts the valve clearance provided between the intake / exhaust valve and rocker arm or the rocker arm and cylinder head of the internal combustion engine, and between the intake / exhaust valve and camshaft, to practical use. Has been. Specifically, the lash adjuster includes an external oil supply type lash adjuster that uses engine oil and a sealed lash adjuster in which hydraulic oil is sealed.

  An example of the sealed lash adjuster is disclosed in Patent Document 1. The lash adjuster disclosed in Patent Document 1 includes a body, a plunger, a first seal member attached to the plunger, a part of the plunger exposed from the body, and an opening end of the body and the plunger. And a second seal member covering a gap formed between the two. In this sealed lash adjuster, the plunger 2 to which the first seal member is attached is fitted into the body, and the plunger slides up and down. The plunger and the body are each provided with a sealing member, thereby preventing the hydraulic oil from leaking outside.

The relationship between the pressure distribution on the sliding contact surface of the first seal member and the thickness of the oil film between the body and the plunger is expressed by the following equations (1) and (2) according to the inverse theory of fluid lubrication.

  Here, hop indicates the thickness of the oil film during the plunger pushing process, and hoM indicates the thickness of the oil film during the plunger pulling process. Further, | dp / dx | maxP represents the maximum contact pressure gradient on the hydraulic pressure side during the plunger pushing step, and | dp / dx | maxM represents the maximum contact pressure gradient on the hydraulic pressure side during the plunger pulling step. U represents the speed of the plunger (cm / s), and μ represents the viscosity (pa · s) of the oil. Thus, the oil film thicknesses hop, hoM are determined by the oil viscosity, the plunger speed, and the maximum contact pressure gradient.

  The speed relationship of the sealed lash adjuster is an extension speed> the contraction speed, and the speed relationship of the plunger is a speed of the pulling process> a speed of the pushing process. The encapsulated oil and the external oil are determined so that the viscosity of the encapsulated oil> the viscosity of the external oil. Therefore, in this sealed lash adjuster, the thickness (hoM) of the oil film during the plunger pulling process is larger than the thickness (hop) of the oil film during the plunger pressing process (hoM> hop).

  Further, Patent Documents 2 and 3 disclose other technologies that are considered to be related to the present invention.

JP 2008-223489 A Japanese Patent Laid-Open No. 63-269653 JP 2002-285808 A

  In the technique of Patent Document 1, the thickness of the oil film is controlled by the above-described fluid lubrication inverse theory, thereby preventing the enclosed oil from flowing out and the external oil from flowing into the inside. However, when the internal combustion engine is operating at high speed, the lift loss (shrinkage amount) is as small as several tens of μm, and the first seal member is only slightly deformed. For this reason, it is difficult to control the thickness of the oil film using the speed difference of the plunger in the fluid lubrication inverse theory, and there is a possibility that the enclosed oil may flow out and the external oil may flow into the inside.

  In order to solve the above problems, the inventors of the present application have made extensive studies, and as a result, the first seal member and the second seal member in which the oil discharge side is stealed and the cross-sectional shape is asymmetrical are the oil discharge side By disposing the sliding portions of the body and the plunger so as to be opposite to each other, different fluids (that is, oil outside the plunger and oil sealed in the high pressure chamber) are used at both ends of the seal structure. In this case, the inventors have found an invention related to “sliding portion seal structure and lash adjuster” that can prevent both fluids from mixing (unpublished, Japanese Patent Application No. 2009-095356).

The present invention has been made in view of such knowledge, and provides a lash adjuster capable of suppressing mixing of both fluids when different fluids are used at both ends of the seal structure. With the goal.

In order to achieve the above object, a lash adjuster according to the present invention includes a cylindrical body having a first body and a second body press-fitted into a tip portion of the first body, and a reservoir chamber therein. A plunger that is slidably inserted into the body and has a portion that protrudes to the atmosphere side from the tip of the second body, and that forms a high-pressure chamber between the bottom of the first body, The plunger is slidably in contact with the first body, and the cross-sectional shape including the plunger axis is parallel to the sliding direction of the plunger and the body and is perpendicular to the sliding direction and has a width in the sliding direction. a first sealing member is symmetrical with respect to the axis located in the middle, the provided first body, the contact plunger sliding, the axis of the plunger parallel to the sliding direction of the said body plunger cross-sectional, including Is shaped, characterized in that it comprises a second sealing member is asymmetrical with respect to the axis located in the middle in the width direction of the sliding direction orthogonal to the sliding direction.

In particular, the lash adjuster of the present invention can be configured such that the second seal member has a maximum contact pressure with the plunger while the plunger slides toward the high pressure chamber side of the body.
With the above configuration, it is possible to suppress the external oil from flowing into the inside by the second seal member while the plunger slides toward the high pressure chamber side of the body. Therefore, when different fluids are used at both ends of the seal structure, mixing of both fluids can be suppressed.

In the lash adjuster of the present invention, the first seal member has a cross-sectional shape provided on the high-pressure chamber side with respect to the second seal member, and having a protrusion that is in sliding contact with the first body, and the second seal member However, it can be set as the structure which is provided in the air | atmosphere side rather than the said 1st sealing member, and is a cross-sectional shape by which the part of the air | atmosphere side of the side which contacts the said plunger was stealed.
With the above configuration, it is possible to prevent the sealed oil from flowing out to the outside by the first seal member that is provided on the high-pressure chamber side than the second seal member and has a cross-sectional shape having a protrusion that is in sliding contact with the first body. it can. Further, the second seal member, which is provided on the atmosphere side of the first seal member and has a cross-sectional shape in which a portion of the atmosphere side on the side that comes into sliding contact with the plunger is stealed, suppresses inflow of external oil to the inside. can do. Therefore, when different fluids are used at both ends of the seal structure, mixing of both fluids can be suppressed.

In the lash adjuster according to the present invention, the second seal member may have a cross-sectional shape in which a part of the high pressure chamber side in sliding contact with the plunger continuously decreases toward the high pressure chamber side. it can.
With the above configuration, the friction when the plunger slides to the atmosphere side of the body can be reduced. For example, the performance of the plunger at the time of cold start is improved, so the noise of the valve train is suppressed. can do.

According to the lash adjuster of the present invention, when different fluids are used at both ends of the seal structure, mixing of both fluids can be suppressed.

It is the figure which showed one structural example of the lash adjuster of the Example. (A)-(C) have shown the cross-sectional shape of the conventional sealing member. The cross-sectional shape of the 1st seal member of an Example and the 2nd seal member is shown. The surface pressure distribution of the first seal member and the second seal member when the plunger slides toward the high-pressure chamber is shown. (A) shows the surface pressure distribution of the first seal member, and (B) shows the surface pressure distribution of the second seal member. The correlation with the frictional force and pressure at the time of a 1st seal member and a 1st body contacting a 2nd seal member and a plunger is shown.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a lash adjuster according to the present invention.

  A lash adjuster 100 shown in FIG. 1 includes a first body 1, a second body 7, a plunger 2, a check valve 3, a plunger spring 4, a first seal member 5, a ball plug 6, as a basic configuration. And a second seal member 20.

  The first body 1 is composed of a cylindrical member, and a plunger 2 is fitted into the first body 1 so as to be slidable in a direction parallel to the central axis. The lash adjuster 100 in this embodiment is configured to fit the plunger 2 into the first body 1 from the atmosphere side. A second body 7 is press-fitted into the distal end portion of the first body 1, and a catching portion 22 for restricting the protrusion of the plunger 2 is disposed on the second body 7. This catching portion 22 functions as a stopper for the plunger 2. The second body 7 may be held on the first body 1 by caulking or welding.

  The plunger 2 is constituted by a substantially cylindrical member, and a reservoir chamber 10 is formed therein. The reservoir chamber 10 may be formed in an appropriate shape. An injection hole 2a for injecting oil (fluid) is formed at the distal end side of the plunger 2, and a ball plug 6 for sealing the injected oil or gas is press-fitted into the injection hole 2a. . A predetermined amount of oil is injected, and gas (for example, air obtained from the manufacturing atmosphere) exists in the remaining space of the reservoir chamber 10. For example, silicon oil is applied as the oil to be sealed.

  A communication hole 2b communicating with the high-pressure chamber 11 is formed at the rear end of the plunger 2, and a check valve 3 is disposed in the communication hole 2b. A high pressure chamber 11 is formed on the rear end side of the plunger 2, and a plunger spring 4 is disposed in the high pressure chamber 11. The check valve 3 opens when the plunger spring 4 urges the plunger 2 so as to protrude to the atmosphere side (upward in FIG. 1), and only allows the oil to move from the reservoir chamber 10 to the high-pressure chamber 11. And block the movement of oil in the opposite direction.

  The plunger 2 has a recycle hole 2c leading from the sliding surface 12 to the reservoir chamber 10 so that the opening 2f on the reservoir chamber 10 side is always closer to the high pressure chamber 11 side than the oil level L of the oil when in use. Is formed. The lash adjuster 100 according to the present embodiment is attached to an internal combustion engine (not shown) in a state inclined by 45 degrees with respect to the vertical direction, and therefore, the oil level L is shown in a state inclined by 45 degrees in FIG. Yes.

  The recycle hole 2c is formed so as to be orthogonal to the center axis toward the center axis, and the sliding surface 12 of the plunger 2 has the same height (position in the sliding direction) as the recycle hole 2c over the entire circumference. Thus, a groove 2d is formed. Further, a groove portion 2e is formed over the circumference on the sliding surface 12 on the distal end side of the plunger 2, and a first seal member 5 is provided in the groove portion 2e for preventing oil from entering from the outside. ing. The first sealing member 5 seals the gap between the first body 1 and the plunger 2 at a position closer to the tip (atmosphere side) of the plunger 2 than the position of the recycling hole 2c. As the first seal member 5, for example, an X seal (specifically, an oil seal having a plurality of lips whose cross section is X-shaped) can be applied. Means may be applied. A specific example of the X seal is disclosed in Japanese Patent Publication No. 62-29605.

  A groove 1a is formed on the inner peripheral surface of the first body 1 over the entire circumference, and a second seal member 20 for preventing the inflow of oil from the outside is provided in the groove 1a. The material of the second seal member 20 is, for example, rubber, but is not limited thereto, and an appropriate material may be applied.

  In the lash adjuster 100, first, the plunger 2 assembled with the first seal member 5 is inserted into the first body 1, and then the second seal member 20 is assembled into the groove 1a, and then the second body 7 is press-fitted. It is. Thus, by separating the housing of the lash adjuster 100 into the first body 1 and the second body 7, the first seal member 5 and the second seal member 20 do not contact each other when the lash adjuster 100 is assembled. In addition, the plunger 2 can be fitted into the first body 1. Therefore, it is possible to avoid the first seal member 5 and / or the second seal member 20 from being damaged when the lash adjuster 100 is assembled. Further, since the casing of the lash adjuster 100 is separated, the processing of the groove 1a is facilitated.

  2A to 2C show the cross-sectional shapes of a conventional seal member, and FIG. 3 shows the cross-sectional shapes of the first seal member 5 and the second seal member 20 of the embodiment.

  As shown in FIGS. 2 (A) to (C), the cross-sectional shape of the conventional seal member is either a circle, a D-shape, or a rectangle having a protrusion that contacts the sliding surface of the plunger. Each cross-sectional shape is symmetrical with respect to an axis orthogonal to the sliding direction of the first body 1 and the plunger 2 (that is, the center line C).

  On the other hand, as shown in FIG. 3, the cross-sectional shape of the first seal member 5 is similar to that of FIG. 2C, and has protrusions that contact the sliding surface of the first body 1 (or slide with the first body 1. The air contact side and the high pressure part 11 side are rectangles (partially stealed), and are symmetrical with respect to the center line C. On the other hand, the second seal member 20 has a cross-sectional shape in which the atmosphere side (that is, the surface pressure increasing side and the oil discharge side 21) in sliding contact with the plunger 2 is partially stealed. And asymmetric with respect to the center line C. Further, the second seal member 20 has a cross section in which a part of the side of the high pressure chamber 11 on the side that comes into sliding contact with the plunger 2 (the side on which the surface pressure is reduced) decreases continuously (tapered) toward the high pressure chamber 11 side. Shape. As shown in FIG. 3, the first seal member 5 and the second seal member 20 are arranged so that the oil discharge side 21 of the second seal member 20 is opposite to the direction of the first seal member 5. ing.

  FIG. 4 shows the surface pressure distribution of the first seal member 5 and the second seal member 20 when the plunger 2 slides toward the high-pressure chamber 11 side.

  As shown in FIG. 4, since the cross-sectional shape of the first seal member 5 is symmetrical with respect to the center line C, a sufficient contact area with the first body 1 can be secured. Therefore, the contact pressure (surface pressure) distribution between the first seal member 5 and the first body 1 becomes a semi-elliptical shape regardless of the sliding direction of the plunger 2. Thereby, the first seal member 5 can withstand both the pressure of the fluid on the high pressure chamber 11 side caused by the sliding of the plunger 2 and the pressure accompanying the change in the distance between the first seal member 5 and the second seal member 20. Can do. Therefore, the oil (fluid) enclosed in the lash adjuster 100 can be more appropriately suppressed from flowing out.

  On the other hand, as shown in FIG. 4, since the cross-sectional shape of the second seal member 20 is asymmetric with respect to the center line C, the surface pressure on the oil discharge side 21 is increased. That is, since the contact pressure between the second seal member 20 and the plunger 2 shows the maximum value while the plunger 2 slides toward the high pressure chamber 11 side of the first body 1, the maximum contact pressure gradient on the discharge side 21 increases. . Thereby, the thickness of the oil film on the oil discharge side 21 is reduced, and the oil (that is, the oil outside the plunger 2) is more appropriately transferred to the outside of the lash adjuster 100 while the plunger 2 slides toward the high pressure chamber 11 side. Can be scraped.

  FIG. 5A shows the surface pressure distribution of the first seal member 5, and FIG. 5B shows the surface pressure distribution of the second seal member 20.

  As shown in FIGS. 5A and 5B, the surface pressure distribution of the first seal member 5 has a semi-elliptical shape, but the surface pressure distribution of the second seal member 20 has a semi-decent shape with a bias. . For this reason, the surface pressure of the second seal member 20 has a higher maximum contact pressure gradient on the discharge side 21 than the surface pressure of the first seal member 5.

  FIG. 6 shows the correlation between the frictional force and the pressure when the first seal member 5 and the first body 1 and the second seal member 20 and the plunger 2 are in contact with each other.

  As shown in FIG. 3, the second seal member 20 has a portion of the side of the high pressure chamber 11 that is in sliding contact with the plunger 2 (the side that reduces the surface pressure) continuously toward the high pressure chamber 11 side (tapered). (D) reduced cross-sectional shape. Therefore, as shown in FIG. 6, the frictional force when the second seal member 20 and the plunger 2 are in sliding contact with each other greatly reduces the friction when the plunger 2 slides to the atmosphere side of the first body 1. Furthermore, it is 7 to 12% lower than the friction force when the first seal member 5 and the first body 1 are in sliding contact. Therefore, the lash adjuster 100 using the first seal member 5 and the second seal member 20 having a cross-sectional shape as shown in FIG. 3 is more stretchable than the lash adjuster using the conventional seal member of FIG. Excellent, zero rush function is maintained, and noise in the valve train can be suppressed.

  As described above, the lash adjuster of the present embodiment includes a first seal member in which the shape of the cross section parallel to the sliding direction of the first body and the plunger is symmetrical with respect to the axis orthogonal to the sliding direction; And a second seal member having a cross-sectional shape parallel to the sliding direction of the first body and the plunger that is asymmetrical with respect to an axis orthogonal to the sliding direction. It is possible to appropriately suppress the outflow and the external oil from flowing into the lash adjuster. Therefore, when different fluids are used at both ends of the seal structure, mixing of both fluids can be suppressed.

  Further, in the lash adjuster of the present embodiment, the first seal member is provided on the high pressure chamber side with respect to the second seal member, and has a cross-sectional shape having a protrusion that slides on the body, so that the contact area with the first body Therefore, it is possible to withstand both the pressure of the fluid on the high-pressure chamber side caused by the sliding of the plunger and the pressure accompanying the change in the distance between the first seal member and the second seal member. Therefore, it is possible to more appropriately suppress the lash adjuster filled oil from flowing out.

  In the lash adjuster of the present embodiment, the second seal member is provided on the atmosphere side with respect to the first seal member, and a part of the atmosphere side on the side in sliding contact with the plunger has a cross-sectional shape. The contact pressure between the second seal member and the plunger takes the maximum value while the plunger slides toward the high pressure chamber side of the body. Therefore, it is possible to more appropriately scrape the oil outside the plunger to the outside of the lash adjuster while the plunger slides toward the high pressure chamber.

  Further, in the lash adjuster of the present embodiment, the second seal member 20 has a cross-sectional shape in which a part of the high pressure chamber side on the side in sliding contact with the plunger continuously decreases toward the high pressure chamber side. Friction when sliding to the atmosphere side of the body can be reduced. Therefore, for example, since the extension performance of the plunger at the time of cold start is improved, the noise of the valve train can be further suppressed.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

  For example, the casing of the lash adjuster 100 of the present embodiment is a separate type that combines the first body 1 and the second body 7, but is not limited thereto, and may be an integrated type.

  Further, the casing of the lash adjuster 100 of the present embodiment is a casing composed of a body and a lid, and after the plunger 2 is fitted into the body from the high pressure chamber 11 side, the lid is press-fitted into the body, and the lid is welded. And it is good also as a structure which unites a body. Thereby, since the plunger 2 can be fitted and inserted into the body without the first seal member and the second seal member being in contact with each other, damage to the first seal member 5 and / or the second seal member 20 is avoided. be able to.

  Furthermore, the present invention is not limited to a lash adjuster, and may be used in a structure that uses different fluids on both sides of a seal structure that uses two seal members.

DESCRIPTION OF SYMBOLS 1 1st body 2 Plunger 3 Check valve 4 Plunger spring 5 1st seal member 6 Ball plug 7 2nd body 11 High pressure chamber 20 2nd seal member 21 Outlet side 22 Entrapment part 100 Rush adjuster

Claims (4)

A cylindrical body having a first body and a second body press-fitted into the tip of the first body;
A high pressure chamber having a reservoir chamber therein, slidably inserted into the body, and having a portion protruding to the atmosphere side from the tip of the second body, and between the bottom of the first body A plunger to form a
A shape of a cross-section provided on the plunger, in sliding contact with the first body, parallel to the sliding direction of the plunger and the body and including the axis of the plunger is orthogonal to the sliding direction, and the width in the sliding direction A first seal member that is symmetrical with respect to an axis located in the middle of
A cross-sectional shape that is provided on the first body, is in sliding contact with the plunger, is parallel to the sliding direction of the body and the plunger, and includes the axis of the plunger, and is perpendicular to the sliding direction and has a width in the sliding direction. A second seal member that is asymmetric with respect to an axis located in the middle of the direction ;
A lash adjuster comprising:   The lash adjuster according to claim 1, wherein the second seal member has a maximum contact pressure with the plunger while the plunger slides toward the high pressure chamber side of the body. The first seal member is provided on a higher pressure chamber side than the second seal member, and has a cross-sectional shape having a protrusion that is in sliding contact with the first body,
The said 2nd seal member is provided in the atmosphere side rather than the said 1st seal member, It is the cross-sectional shape by which the part of the atmosphere side of the side which slidably contacts with the said plunger was stealed. 2. The lash adjuster according to 2.   4. The lash adjuster according to claim 3, wherein the second seal member has a cross-sectional shape in which a part of the high pressure chamber side that is in sliding contact with the plunger continuously decreases toward the high pressure chamber side.

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