JPH0676774U - Sealing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sealing device that can cope with pressure fluctuations on the combustion chamber side, is not affected by the atmosphere, and can prevent leakage of lubricant. An intake valve 5 is reciprocally inserted into a shaft hole 2 opening in a gas chamber 3 inside a cylinder head 1, and the shaft hole 2 is inserted into an end face 23 which is an opening portion of the shaft hole 2 on the gas chamber 3 side. The engine oil 4 between the sliding surface between the inner circumference and the intake valve 5 is the gas chamber 3
In order to prevent leakage to the seal lip 71, the edge portion 72 slidably and sealingly contacts the outer periphery of the intake valve 5.
Sealing device A provided with an annular first seal member 7 having
At the gas chamber 3 side of the first seal member 7, an annular second seal member 8 for slidably sealingly contacting the intake valve 5 and shutting off gas pressure to the first seal member 7 is provided. However, the second seal member 8 is not in contact with the seal lip 71 of the first seal member 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a reciprocating sealing device used in, for example, a valve stem sliding portion of an intake and exhaust valve of an engine.

[0002]

[Prior art]

 Conventionally, an engine intake / exhaust valve has a valve formed in a shaft hole that connects a gas chamber formed inside the cylinder head and serving as an intake or exhaust passage with the head upper chamber side located above the cylinder head outside the gas chamber. The stem is reciprocally inserted. Lubricating oil is supplied to the sliding portion between the shaft hole and the valve stem from the head upper chamber side to lubricate the sliding surface.

When the oil supply amount is insufficient, wear of the sliding surface between the valve stem and the shaft hole is accelerated, while when the oil supply amount is excessive, the amount of oil mixed into the combustion chamber through the gas chamber increases. However, the deposit inside the engine increases.

Therefore, conventionally, a sealing device is provided in the head upper chamber side opening of the shaft hole in the upper part of the engine head, and the oil supply amount entering between the shaft chamber and the sliding surface of the valve stem from the cam chamber side is adjusted to an appropriate amount. Was.

[0005]

[Problems to be solved by the device]

 However, it is difficult to adjust the oil supply amount stably without excess or deficiency.Therefore, it is not enough to install a sealing device on the gas chamber side of the guide hole to control the lubricating oil supply amount to the sliding part. It is considered to secure the amount of lubrication and prevent leakage to the gas chamber side.

However, as described above, when the sealing device is arranged on the gas chamber side, the sealing device is directly exposed to the gas in the gas chamber. Therefore, the contact state between the sealing device and the valve stem changes due to the change in gas pressure.For example, if the gas pressure becomes large, the sealing device will deform significantly and the seal surface pressure will decrease. A gap is opened in the seal, which increases the amount of leakage into the gas chamber.

Further, there is also a problem that the material of the sealing device itself is rapidly deteriorated because it is in direct contact with the gas.

The present invention has been made to solve the above-mentioned problems of the prior art. The purpose of the present invention is to arrange a sealing device on the gas chamber side so that the shaft and the shaft hole always slide. Maintaining a sufficient lubrication condition between the surfaces and devising the structure of the sealing device will minimize the leakage of the lubricant to the gas chamber side regardless of the pressure in the gas chamber. .

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, according to the present invention, a shaft is reciprocally inserted into a shaft hole that opens in a gas chamber inside a housing, and the shaft hole is opened at the gas chamber side opening. In order to prevent the lubricant between the sliding surface between the circumference and the shaft from leaking to the gas chamber, the first annular seal having a sealing lip whose slidable end slidably contacts the outer circumference of the shaft. In the sealing device provided with a member, an annular second seal member is provided on the gas chamber side of the first seal member for slidably sealingly contacting the shaft to shut off gas pressure to the first seal member. It is characterized in that the second seal member is disposed so as not to contact the seal lip of the first seal member.

[0010]

[Action]

 In the sealing device configured as described above, since the second seal member is provided on the gas chamber side of the first seal member, the first seal member is covered with the second seal member, and the gas is The pressure on the chamber side is received by the second seal member, and the pressure is not transmitted to the first seal member. Further, the atmosphere on the gas chamber side does not affect the first seal member.

[0011]

【Example】

 The present invention will be described below based on the illustrated embodiment.

In FIG. 1 showing a sealing device according to a first embodiment of the present invention, A shows the whole valve stem seal as a sealing device, and this valve stem seal is shown in, for example, FIGS. ) Used for the sliding portion of the valve stem 52 of the intake valve 5 of the engine as shown in FIG.

The intake valve 5 controls the supply timing of a mixed gas of fuel 63 and air 64 supplied to the combustion chamber 6 of the engine. The intake valve 5 has a linearly extending valve stem 52 and one end of the valve stem 52. And a disc-shaped valve body portion 51 that is integrally provided in the.

The valve stem 52 is reciprocally inserted into a shaft hole 2 formed through the cylinder head 1 via a sleeve-shaped valve stem 52. The shaft hole 2 has one end opening to the intake passage 11 inside the cylinder head 1 and the other end opening to the head upper chamber 12 in which a drive mechanism such as a cam is arranged. One end of the valve stem 52 is above the head. It projects into the chamber 12. A spring receiver 54 is provided at the tip of the protruding portion 53 of the valve stem 52. Between the spring receiver 54 and the upper surface of the cylinder head 1, a direction in which the valve stem 52 is projected into the head upper chamber 12, that is, the valve body portion. A spring 55 is installed which constantly urges 51 in the valve seat 61 of the intake port 65 to close the valve.

A cam or link mechanism (not shown) moves the protrusion 53 of the valve stem 52 in the direction of pushing it into the shaft hole 2, thereby separating the valve body 51 from the valve seat 61 and opening the valve. It is like this.

On the other hand, the engine oil 4 is supplied to the head upper chamber 12, and the engine oil 4 is supplied between the sliding surfaces of the stem guide 21 and the valve stem 52 to ensure lubrication between the sliding surfaces. Has been. Incidentally, reference numeral 62 in the figure is an ignition plug.

The sealing device A of the present invention is provided at an end portion 22 which is an opening portion on the intake passage 11 side of a stem guide 21 which is an opening portion of the shaft hole 2 on the gas chamber 3 side.

The sealing device A prevents the engine oil 4 for lubrication between the sliding surface between the inner periphery of the shaft hole 2 and the valve stem 52 from leaking to the intake passage 11, and the lip tip is the valve. An annular first seal member 7 having a seal lip 71 slidably sealingly contacting the outer periphery of the stem 52, and an intake passage 11 side of the first seal member 7, the first seal member being provided. The seal lip 71 of FIG. 7 is composed of a second seal member 8 which is not in contact with the seal lip 71, and a metal ring 23 for integrally assembling the first seal member 7 and the second seal member 8. .

The first seal member 7 is a ring member made of a rubber-like elastic material, and is integrally molded with the first seal fixing portion 73 fitted on the inner circumference of the metal ring 23. And a seal lip 71 to be held. The first seal fixing portion 73 has a substantially rectangular cross section, the outer peripheral surface of which is fitted to the inner periphery of the metal ring 23, the one end face 74 in the axial direction is in close contact with the end face 22 of the stem guide 21, and the other end face is the first end. It is in close contact with the end surface of the second seal member 8.

In this embodiment, a plurality of fixing lips 75 and 76 are formed on the outer periphery of the first seal fixing portion 73 and the contact portion with the stem guide 21 to increase the sealing surface pressure.

On the other hand, the seal lip 71 extends from the end of the first seal fixing portion 73 on the gas chamber 3 side inward in the radial direction at a right angle to the valve stem 52. The inner end portion of the seal lip 71 has an inclined surface that gradually decreases in diameter from the second seal member 8 side toward the stem guide 21. The lip tip 72 of the inner end of the seal lip 71 on the valve stem 52 side is slidably and sealingly contacted with the outer circumference of the valve stem 52.

The thickness of the seal lip 71 in the axial direction is approximately half the axial width of the first seal fixing portion 73, and the gap between the seal lip 71 and the end surface 22 of the shaft hole 2 is small. It is separated by a predetermined distance.

On the other hand, the second seal member 8 is made of resin, and includes a second seal body 80 fitted to the inner circumference of the metal ring 23, and a seal lip 81 integrally formed with the second seal body 80. Composed.

As the resin material of the second seal member 8, a resin material having high pressure resistance, low friction and excellent wear resistance is selected. Especially in the case of engine valve stem seals, materials with excellent heat resistance and gasohol resistance to fuel are selected.

The second seal fixing portion 83 also has a substantially rectangular cross section, the outer peripheral surface of which fits into the inner periphery of the metal ring 23, and the end surface of one side in the axial direction is in close contact with the end surface of the first seal member 7 and the other side. Of the metal ring 23 is in close contact with the disk portion 24 extending radially inward.

On the other hand, the seal lip 81 extends inward in the radial direction so as to incline toward the stem guide 21 side from the end of the second seal fixing portion 83 on the gas chamber 3 side. The tip 82 is in slidable sealing contact with the outer circumference of the valve stem 52.

The axial thickness of the seal lip 81 is smaller than that of the seal lip 71 of the first seal member 7, and the seal lip 81 and the first seal member 7 are separated from each other by a predetermined distance. A space 9 is formed.

On the other hand, the metal ring 23 has an L-shaped cross section, and is divided into a tubular portion 25 and a disc portion 24 extending inward in the radial direction from one end of the tubular portion 25 depending on its shape. The first seal member 7 and the second seal member 8 are fitted to the inner peripheral surface of the cylindrical portion 25, and the metal ring 23 is attached to the mounting portion 26 of the metal ring 23 on the outer peripheral side of the end surface 22 of the shaft hole 2. The cylindrical portion 25 of 23 is fitted, and the first seal member 7 and the second seal member 8 are assembled so as to be sandwiched between the end surface 22 of the shaft hole 2 and the disc portion 24 of the metal ring 23. Has become.

As described above, the second seal member 8 not only backs up the leakage of the engine oil 4, but also the fuel 64 supplied from the fuel gas supply port 31 in the gas chamber 3 is the first seal member. 7 has the effect of preventing it from being adhered to and being affected by erosion and the like, and also has the effect of blocking the pressure in the combustion chamber 6 due to combustion of the fuel 64 so as not to be transmitted to the first seal member 7. There is.

The second seal member 8 allows the first seal member 7 to sufficiently function as a seal lip without being affected by the atmosphere in the gas chamber 3 and has a long life. Become.

Although the present embodiment is the sealing device A installed on the sliding part of the valve stem of the intake part, it can be used not only for the exhaust part but also for the sealing device used in a bad atmosphere. Widely applicable.

A sealing device A having a second sealing member 8 according to another embodiment of the present invention is shown in FIGS. 2 (a), 2 (b) and 2 (c), respectively.

FIG. 2A shows a sealing device A according to a second embodiment of the present invention, in which the structure of the first seal member 7 is different from that of the first embodiment, and this first seal member is different. The seal lip 71 has a large thickness in the axial direction even in the seal lip 71, and the lip tip 72 has an inclined surface that is substantially symmetrical with respect to the radial center line. When the intake valve 5 slides, this substantially symmetrical inclined surface causes the engine oil 4 as a lubricant on the shaft hole 2 side to adhere to the sliding portion of the intake valve 5 and slide smoothly. .

FIG. 2B shows a sealing device A according to a third embodiment of the present invention, in which the first seal member 7 is similar to the seal lip 71 of the first embodiment, The lip tip 72 is similar to the second embodiment. With this configuration, even when the first seal member 7 is pressed by the shaft hole 2 and the second seal member 8, the contact area of the lip tip 72 with the intake valve 5 does not change, and the friction force increases. There is no. Further, the second seal member 8 has a thick seal lip 81 and can cope with a case where the pressure fluctuation on the gas chamber 3 side is large, and the lip tip 82 is an inclined surface which is substantially symmetrical with respect to the radial center line. Therefore, even at the lip tip 82 of the second seal member 8, the engine oil 4 as a lubricant can be attached to the sliding portion of the intake valve 5 and smoothly slide.

FIG. 2 (c) shows a sealing device A according to a fourth embodiment of the present invention, in which the first seal member 7 is the same as that of the third embodiment and the second seal member 8 is used. Has a thickness that is approximately the same in the axial direction up to the seal lip 81 and the lip tip 82, and is radially inward so as to incline toward the gas chamber 3 side, contrary to the first and second embodiments. With the configuration extending toward, it is possible to cope with the case where the pressure on the gas chamber 3 side is much higher than the pressure on the seal side.

In the first embodiment, the second embodiment, the third embodiment and the fourth embodiment of the present invention, the respective seal lips 71, 81 of the first seal member 7 and the second seal member 8 are The seal member main body is in close contact with the seal member main body, although the space 9 is formed so as to form a space 9.

It goes without saying that various variations can be considered in addition to the embodiment shown here.

[0038]

[Effect of device]

 The present invention has the above-described configuration and operation. The second seal member is provided on the gas chamber side of the first seal member so that the pressure on the gas chamber side is not transmitted to the first seal member. It is possible to prevent the leakage of the lubricant without the first seal member being deformed by the pressure. In addition, since the atmosphere on the gas chamber side does not affect the first seal member, erosion of the first seal member is eliminated and the life of the sealing device is extended.

[Brief description of drawings]

FIG. 1 (a) is a schematic cross-sectional view of the periphery of a sealing device according to a first embodiment of the present invention, and FIG. 1 (b) is a cross-sectional view of a main part of the sealing device according to a first embodiment of the present invention. is there.

2 (a), (b) and (c) are cross-sectional views of a main part of a sealing device according to second, third and fourth embodiments of the present invention.

[Explanation of symbols]

 A Sealing device 1 Cylinder head (housing) 2 Shaft hole 3 Gas chamber 4 Engine oil (lubricant) 5 Intake valve 6 Combustion chamber 7 First seal member 8 Second seal member 9 Space 11 Intake passage 12 Head upper chamber 21 Stem guide 22 End face (opening) 23 Metal ring 24 Disc part 25 Cylindrical part 26 Attachment part 31 Fuel gas supply port 51 Valve body part 52 Valve stem (shaft) 53 Projection part 54 Spring bearing 55 Spring 61 Valve seat part 62 Spark plug 63 Fuel 64 Air 65 Intake port 71,81 Seal lip 72,82 Lip tip 73,83 Fixed part 74 End face 75,76 Fixed lip 80 Seal body

Claims (1)

[Scope of utility model registration request] 1. A shaft is reciprocally inserted into a shaft hole that opens into a gas chamber inside a housing, and a gap between the inner surface of the shaft hole and a sliding surface between the shaft hole and the gas chamber side is inserted into the shaft hole. To prevent the lubricant from leaking into the gas chamber,
In a sealing device provided with an annular first seal member having a seal lip whose lip tip slidably and slidably contacts the shaft outer periphery, the shaft is slidable on the gas chamber side of the first seal member. An annular second seal member for sealingly contacting the first seal member to shut off the gas pressure to the first seal member, and the second seal member is not in contact with the seal lip of the first seal member. A sealing device characterized by the above.