JP5384689B2 - Seal structure between the first and second parts - Google Patents

Description

  The present invention relates to a seal structure between first and second parts.

  Conventionally, a lash adjuster that automatically adjusts a valve clearance provided between an intake / exhaust valve of an internal combustion engine and a cylinder head to substantially zero has been put into practical use. According to this lash adjuster, the noise generated by the interference between the intake / exhaust valve and the cylinder head is eliminated in terms of function, and the work of periodically checking and adjusting the valve clearance is unnecessary in terms of maintenance. The lash adjuster includes, for example, an external oil supply type that uses engine oil. In the case of this external lubrication type lash adjuster, if the injection amount of engine oil is inappropriate or if deteriorated oil is used as it is, there is an increased risk of air and foreign matter entering the oil. Function may be impaired. That is, in the external oil supply type lash adjuster, the function of the lash adjuster depends on the quality of engine oil maintenance. On the other hand, the lash adjuster includes a sealed lash adjuster in which a liquid such as oil is sealed. According to such a sealed lash adjuster, the above-described function inhibiting factors can be eliminated.

  As for this sealed lash adjuster, for example, the following sealed lash adjuster has been proposed in Patent Document 1. The sealed lash adjuster proposed by Patent Document 1 includes an oil seal (hereinafter simply referred to as an X seal) having two lips in a cross-sectional X-letter shape between a body and a plunger. The X seal can seal two liquids on both sides of the seal at the same time. Therefore, in this sealed lash adjuster, the oil sealed by the X seal (hereinafter also simply referred to as enclosed oil) flows to the outside, and the engine This is a structure for simultaneously preventing intrusion of an external liquid such as oil (hereinafter also simply referred to as external oil). In addition, for example, Patent Documents 2 to 4 propose techniques that are considered to be related to the present invention.

Japanese Examined Patent Publication No. 62-29605 JP 2005-162138 A JP 2006-132660 A Japanese Utility Model Publication No. 01-124008

  By the way, in order to prevent the engine oil from being mixed into the oil sealed with the X seal, it is necessary to prevent mixing of two liquids (the engine oil and the oil sealed). For this purpose, the X seal is moved back and forth. It is necessary to function as a seal for use. In contrast, reciprocating seals generally require a lubricating oil film on the sliding surface to reduce wear, and functionally, the oil film that comes out in the pushing process (the process that shortens the sealed lash adjuster) is removed. External leakage is prevented by returning to the inside in the pulling process (process in which the sealed lash adjuster extends). However, it is impossible to make the X seal function as a reciprocating seal.

  Here, the plunger stroke required for the lash adjuster is usually about 2 mm to 2.5 mm, and when the engine is stopped, the plunger sinks to the bottom of the body. When the plunger is extended most in the process, the sliding width (stroke) between the plunger and the body may exceed about 2 mm to 2.5 mm. In this regard, the X seal usually tries to maintain the sealing function by deformation without sliding with the body during the reciprocating movement of the plunger, but for example, due to the sudden expansion of the plunger when the engine is started, for example. It may slide with the body. Accordingly, in such a case, it is necessary to prevent the mixing of the two liquids by the movement of the oil film by causing the X seal to function as a reciprocating seal.

  On the other hand, the mixing of the two liquids due to the movement of the oil film occurs when the stroke of the plunger originally exceeds the width where the X seal contacts the body sliding surface. Therefore, in order to prevent mixing of the two liquids, an X seal having a size corresponding to the stroke of the plunger is required. On the other hand, the sealed lash adjuster is preferably as compact as possible from the viewpoint of increasing the degree of freedom in designing the internal combustion engine. However, in consideration of the plunger stroke, the X seal that can prevent mixing of two liquids is considered to inevitably increase the size of the sealed lash adjuster. Conversely, in the X seal that can be applied without increasing the size, It is considered difficult to prevent mixing of the two liquids. In other words, it is impossible to make the X seal function as a seal for reciprocating motion. From this, not only the sealed oil flows out to the outside with one sealing means provided between the body and the plunger. It was found that it was difficult to prevent the intrusion of engine oil from the outside at the same time.

  Also, when starting the engine, especially at a low temperature, the sealed lash adjuster expands to suppress engine hitting sound, and it is an important function for the sealed lash adjuster to quickly make the lash zero. For this reason, taking the sealed lash adjuster 100X shown in FIG. 6 as an example, the spring load of the plunger spring 4 for urging the plunger 2 is set appropriately in order to realize such a function. On the other hand, the shrinking operation of the sealed lash adjuster 100X is caused by the leakage of the enclosed oil from the narrow gap between the plunger 2 and the body 1X, and therefore the speed is slow compared to the speed of extension.

Therefore, since (stretching speed)> (shrinking speed), the plunger speed in the pushing step and the plunger speed in the pulling step in the sealed lash adjuster 100X are:
(Plunger speed of pulling process> plunger speed of pushing process).
Further, the oil to be enclosed is usually selected so that (viscosity of encapsulated oil)> (viscosity of external oil).
On the other hand, the relationship between the pressure distribution on the seal sliding contact surface in the reciprocating seal and the formed oil film thickness is expressed as h _op for the oil film thickness in the pushing process and the maximum contact pressure gradient on the hydraulic side in the pushing process | dp / Dx | _{max, P} , the oil film thickness in the drawing step is h _o M, the maximum contact pressure gradient on the hydraulic side in the drawing step is | dp / dx | _{max, M} , the oil viscosity is μ (pa · s), the plunger When the speed is U (cm / s), the following formulas 1 and 2 are arranged by the fluid lubrication inverse theory.

From the above, in the normal sealed lash adjuster 100X provided with one sealing means (here, the first seal member 5) in the sliding portion of the plunger 2 to prevent the outflow of the encapsulated oil, it is formed in the pulling process. The oil film thickness becomes larger than the oil film thickness formed in the pressing step (formula: h _O M> h _OP ). FIG. 7 is a diagram schematically showing an enlarged thickness of the oil film formed as described above. In the sealed lash adjuster 100X, in the pulling process, as shown in FIG. Whereas an oil film is formed, a thin oil film is formed in the pushing step as shown in FIG. This means that the encapsulated oil is returned to the inside in the pulling process, but if the liquid such as engine oil has penetrated to the seal sliding part at this time, the liquid such as engine oil is removed together with the encapsulated oil. It will be rubbed inside. In other words, the normal sealed lash adjuster 100X has such a feature, which is a factor that causes liquid mixture from the outside.

  Therefore, the present invention has been made in view of the above problems, and provides a seal structure between the first and second parts that can prevent or suppress the intrusion of liquid from the outside and mixing with the liquid sealed inside. The purpose is to do.

In order to solve the above-mentioned problems, the present invention is a first part having a reservoir chamber that moves reciprocally and stores liquid therein, and the first part is fitted and the first part slides. to a second component, a seal structure between first and second parts a difference in moving speed of the first component is caused between the forward scan time of the backward movement, the first part Has a hole communicating the sliding part of the first part and the reservoir chamber of the first part, and the second part is more than the hole of the sliding part of the first part. The first sealing means is provided at a portion on the opening side of the first part, and the opening part is more than the first sealing means of the sliding part of the second part facing the sliding part of the first part. comprising a second sealing means on a portion of the side, pushed in the direction opposite to the first component the direction of the opening side Said first seal when the space formed between the first seal means and the second sealing means is expanded, and the first part protrudes in the direction of the opening side when The first seal is formed at a portion closer to the opening than the hole of the sliding portion of the first component so that the space formed between the first sealing means and the second sealing means is reduced. And the second sealing means at a portion closer to the opening than the first sealing means of the sliding part of the second part facing the sliding part of the first part. It is characterized by providing. According to the present invention, not limited to a sealed lash adjuster, a first part (for example, a moving member such as a piston) that moves reciprocally and a second part (for example, a cylinder or the like) on which the first part slides. Holding member), and the seal structure between the first and second parts, which causes a difference in the moving speed of the first part between the forward movement and the backward movement, can be more reliably sealed. Thus, it is possible to prevent or suppress the liquid from entering from the outside and mixing into the liquid sealed inside. Further, the present invention can prevent or suppress the intrusion of liquid from the outside, and can prevent or suppress the outflow of the sealed liquid, and can exhibit a suitable sealing function.

  In the present invention, the second component may further include a communication hole that communicates with the outside from the space formed between the first sealing means and the second sealing means. According to the present invention, the sliding resistance of the first component when the seal structure between the first and second components is shortened can be reduced.

The present invention is further of the outer wall of the second part may comprise a third sealing means to the portion of the opening side of the second component than the communication hole. According to the present invention, it is possible to prevent or suppress liquid from entering from the outside through the communication hole formed in the second component.

  ADVANTAGE OF THE INVENTION According to this invention, the sealing structure between the 1st and 2nd components which can prevent or suppress that a liquid infiltrates from the outside and mixes in the liquid sealed inside can be provided.

It is a figure which shows typically the structure of 100A of lash adjusters. It is a figure which expands and shows typically the 1st and 2nd seal members 5 and 30 in the most extended state and the shortest state. It is a figure which expands and shows typically the thickness of the oil film formed in the 1st and 2nd sealing members 5 and 30 at the time of operation of lash adjuster 100A. It is a figure which shows typically the structure of the lash adjuster 100B. It is a figure which shows typically the structure of 100C of lash adjusters. It is a figure which shows typically the structure of the normal sealed lash adjuster 100X provided with one sealing means in the sliding part of the plunger 2. FIG. It is a figure which expands and shows typically the thickness of the oil film formed in the 1st seal member 5 at the time of lash adjuster 100X operation.

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

  FIG. 1 is a diagram schematically showing a configuration of a sealed lash adjuster (hereinafter also simply referred to as a lash adjuster) 100A according to the present embodiment. The lash adjuster 100A includes a body 1A, a plunger 2, a check valve 3, a plunger spring 4, a first seal member (corresponding to a first seal means in claims) 5 and a ball plug 6 as basic components. And a cap retainer 7 and a second seal member (corresponding to the second seal means in the claims) 30.

  The body 1A is a bottomed cylindrical member, and a plunger 2 is slidably inserted into the cylinder in a direction parallel to the central axis. A cap retainer 7 for restricting the protrusion of the plunger 2 is disposed at the tip of the body 1A. The cap retainer 7 functions to prevent the plunger 2 from coming off, and does not have a function of sealing a liquid that is about to enter from the outside. The plunger 2 is a cylindrical member, and a reservoir chamber 10 is formed inside. The reservoir chamber 10 may be formed in an appropriate shape. An injection hole 2a for injecting oil (liquid) is formed on 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 can be 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 toward the tip side, and allows only the oil to move from the reservoir chamber 10 to the high-pressure chamber 11 and blocks the reverse movement. To do.

  Further, the plunger 2 is formed with a recycle hole 2c leading from the sliding surface to the reservoir chamber 10 so that the opening on the reservoir chamber 10 side is always closer to the high pressure chamber 11 side than the oil level L of the oil in use. ing. The recycling hole 2c is formed so as to be orthogonal to the central axis toward the central axis, and the sliding surface of the plunger 2 has the same height (position in the sliding direction) as the recycling hole 2c over the entire circumference. A groove 2d is formed. Further, a groove 2e is formed over the circumference of the sliding surface of the plunger 2 on the opening side of the body 1A, and the first seal member 5 for preventing oil leakage to the outside is formed in the groove 2e. Is arranged. The first sealing member 5 seals a slight gap between the body 1A and the plunger 2 closer to the opening of the body 1A than the recycling hole 2c.

  With the above configuration as the basic configuration of the lash adjuster 100A, the lash adjuster 100A further includes a second seal member (second seal means) 30 in this embodiment. The second seal member 30 is configured to prevent the ingress of external oil, and is disposed in the groove 1aA formed on the sliding surface of the body 1A. That is, the lash adjuster 100 </ b> A includes the first seal member 5 at the sliding portion of the plunger 2 and the second seal member 30 at the sliding portion of the body 1 </ b> A facing the sliding portion of the plunger 2. .

  The groove portion 1aA is formed over the entire circumference of a portion closer to the opening of the body 1A than the groove portion 2e in a state where the lash adjuster 100A is most extended among the sliding surfaces of the body 1A. In other words, the groove portions 1aA and 2e are formed so that the first and second seal members 5 and 30 do not come into contact with each other when the lash adjuster 100A is most extended (see FIG. 2A). . Thus, in the lash adjuster 100A in which the groove portions 1aA and 2e are respectively formed, the first and second seal members 5 and 30 are most separated from each other when the lash adjuster 100A is most contracted (FIG. 2B). reference).

  That is, in the lash adjuster 100A, when the plunger 2 is pushed in, a space K that is a clearance between the body 1A and the plunger 2 formed between the first seal member 5 and the second seal member 30 is expanded, and The first seal member 5 is provided on the sliding portion of the plunger 2 so that the space K formed between the first seal member 5 and the second seal member 30 is reduced when the plunger 2 protrudes. In addition, a second seal member 30 is provided on the sliding portion of the body 1 </ b> A facing the sliding portion of the plunger 2. The first and second seal members 5 and 30 are more specifically realized by O-rings in this embodiment, but may be realized by appropriate sealing parts such as an oil seal. The cross-sectional shape of the first and second seal members 5 and 30 may be an appropriate shape such as a circle or a square.

  Since the lash adjuster 100A includes the first and second seal members 5 and 30 as described above, it is possible to suitably prevent or suppress the intrusion of external oil and the leakage of sealed oil. FIG. 3 is a diagram schematically showing an enlarged thickness of the oil film formed in the first and second seal members 5 and 30 when the lash adjuster 100A is operated. 3A shows only the state after the lash adjuster 100A is stretched in the pulling process, and FIG. 3B shows only the state after the lash adjuster 100A is contracted in the pushing process. As shown in FIG. 3 (a), the thick oil film of the encapsulated oil formed in the first sealing member 5 in the drawing process is formed by forming a thin oil film in the pushing process as shown in FIG. 3 (b). Scratched into. Further, as shown in FIG. 3A, the thick oil film of the external oil formed in the second sealing member 30 in the pulling process is formed by forming a thin oil film in the pushing process as shown in FIG. It is scraped to the outside.

  That is, in the lash adjuster 100A, the first seal member 5 on the plunger 2 side exerts a scraping action of the enclosed oil, and the second seal member 30 disposed on the body 1A side exerts a scraping action of the external oil. It is possible to eliminate the back and forth between the enclosed oil and the external oil, and as a result, a suitable sealing function can be realized. As described above, it is possible to realize the lash adjuster 100A capable of preventing or suppressing liquid from entering from the outside and mixing into the liquid sealed inside.

  FIG. 4 is a diagram schematically illustrating the configuration of the lash adjuster 100B according to the present embodiment. The lash adjuster 100B is substantially the same as the lash adjuster 100A except that the body 1B is provided instead of the body 1A. The body 1B is substantially the same as the body 1A except that the body 1B further includes a communication hole 31 communicating from the space K formed between the first seal member 5 and the second seal member 30 to the outside. It has become a thing. The communication hole 31 is disposed so as not to be hooked on the seal sliding portions of the first and second seal members 5 and 30. In forming the communication hole 31, it is preferable to consider that the body 1B does not become extremely thin due to the relationship with the groove 1aB and that no burr is produced in manufacturing. According to the lash adjuster 100B, it is possible to suppress an increase in the internal pressure of the space K when the lash adjuster 100B is shortened, which is preferable in that the sliding resistance of the plunger 2 can be further reduced as compared with the lash adjuster 100A. .

  FIG. 5 is a diagram schematically showing a lash adjuster 100C according to the present embodiment. Note that FIG. 5 shows the lash adjuster 100 </ b> C in a state assembled to the cylinder head 50. The lash adjuster 100C is provided with a third seal member 40 (corresponding to the third seal means described in the claims) 40, and according to this, the lash adjuster 100C is provided with a body 1C instead of the body 1B. It is substantially the same as 100B. The body 1C has a groove 1bC in a portion of the outer wall portion of the body 1C that is closer to the opening of the body 1C than the communication hole 31 and a portion that is inserted into the cylinder head 50 that is an assembly target component. It is substantially the same as the body 1B.

  Specifically, the third seal member 40 is mounted in the groove 1bC, and has a configuration for preventing external oil from entering between the cylinder head 50 and the lash adjuster 100C. In the present embodiment, the third seal member 40 is specifically realized by an O-ring, but is not limited thereto, and may be realized by an appropriate seal component such as an oil seal. According to the lash adjuster 100C provided with the third seal member 40, it is preferable in that the external oil can be prevented or suppressed from entering the space K through the communication hole 31 as compared with the lash adjuster 100B. .

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, the first embodiment described above is also an embodiment of a sealing structure between the first and second parts, in which the first part is the plunger 2 and the second part is the body 1A. In the sealing structure between these parts, the first and second parts are not limited to this, and may be a piston and a cylinder.

1 Body 2 Plunger 3 Check Valve 4 Plunger Spring 5 First Seal Member 30 Second Seal Member 40 Third Seal Member 50 Cylinder Head 100 Sealed Rush Adjuster

Claims (3)

A first part having a reservoir chamber that moves reciprocally and stores liquid therein, and a second part into which the first part is inserted and the first part slides, A seal structure between the first and second parts that causes a difference in the moving speed of the first part between the time and the backward movement;
The first part has a hole communicating the sliding part of the first part and the reservoir chamber of the first part;
The first part is provided with a first sealing means at a portion closer to the opening of the second part than the hole of the sliding part of the first part, and the first part is opposed to the sliding part. A second sealing means is provided in a portion closer to the opening than the first sealing means of the sliding part of the second part ,
A space formed between the first sealing means and the second sealing means is enlarged when the first component is pushed in a direction opposite to the direction of the opening ; and When the first part protrudes in the direction of the opening, the space formed between the first sealing means and the second sealing means is reduced. wherein the sliding portion of the second part that faces the sliding portion of the first component with than the hole of the sliding portion comprising said first sealing means on a portion of the opening side A sealing structure between the first and second parts, wherein the second sealing means is provided in a portion closer to the opening than the first sealing means .   The said 2nd component is further provided with the communicating hole connected to the exterior from the said space formed between said 1st sealing means and said 2nd sealing means. The seal structure between the first and second parts. Further among the outer wall of the second part, the first according to claim 2, characterized in that it comprises a third sealing means to the portion of the opening side of the second part than the communicating hole Seal structure between the first and second parts.

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