JPH056109U - Oil seal - Google Patents

Abstract

(57) [Abstract] [Purpose] The contact surface pressure of the seal surface can be maintained even when the fluid pressure in the second fluid chamber rises and is transmitted to the seal lip side through the shaft hole. It is intended to provide an oil seal. Also, the pressure rise in the second fluid chamber is
An object of the present invention is to provide an oil seal capable of preventing the oil lip of the oil seal from acting as a pulling force. [Structure] A valve stem 6 inserted into a shaft hole 4 of a valve guide 5 of a cylinder head 3 that separates a head cover chamber 1 and a port portion 2 from the head cover chamber 1 side to the outer circumference of the valve stem 6. The sub-retainer 11 having the large diameter portion 14 set to the inner peripheral diameter E forming the space D is fixed, and the seal ring 16 is attached to the valve guide 5 on the head cover chamber 1 side. At the position facing the space D, the seal lip 19 that contacts the inner peripheral surface 15 of the large diameter portion 14 is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an oil seal used for a valve device of an automobile engine, for example.

[0002]

[Prior Art]

 FIG. 2 shows a main part of a valve device of an automobile engine. The head cover chamber 100 as the first fluid chamber and the port portion 101 as the second fluid chamber are separated by a cylinder head 102 as a partition wall. A valve guide 104 having a shaft hole 103 is fixed to the cylinder head 102, and a shaft having a length from the head cover chamber 100 to the port portion 101, that is, a valve stem 105 is reciprocated in the shaft hole 103 in the arrow A direction. It is inserted freely. Further, a head 106 is provided at the lower end of the valve stem 105, and is brought into contact with or separated from the valve seat 108 between the port portion 101 and the combustion chamber 107 by the reciprocation of the valve stem 105.

An oil seal 109 is attached to the head cover chamber 100 side of the valve guide 104. This oil seal 109 has a seal body 110 made of a rubber-like elastic body fitted on the outer circumference of the valve guide 104, and a metal ring 111 on which the seal body 110 is baked. A seal lip 112 having a wedge-shaped cross section is formed on the seal body 110 and extends upward from the vicinity of the upper end surface of the valve guide 104. A garter spring 113 is attached to the outer peripheral side of the seal lip 112. The inner circumference of the seal lip 112 contacts the outer circumference of the valve stem 105 to form a seal surface 116.

On the other hand, an annular spring receiver 114 is attached to the upper end side of the valve stem 105, and a valve spring 115 is attached between the spring receiver 114 and the cylinder head 102.

In the above structure, the valve stem 105 is pushed down by the swing arm (not shown) and descends, and rises by the elastic force of the valve spring 115 when the pressure on the swing arm is released. In this way, the valve stem 105 reciprocates to open and close between the port portion 101 and the combustion chamber 107, and the fluid, that is, the high temperature and high pressure gas is sucked and exhausted.

On the other hand, mist-like oil is present in the head cover chamber 100, and a predetermined amount of oil is leaked to the valve guide 104 side via the seal surface 116. As a result, the sliding surface between the valve stem 105 and the valve guide 104 is lubricated.

[0007]

[Problems to be solved by the device]

 However, in the above-described conventional example, when the gas pressure in the port portion 101 rises and the gas pressure blows through the gap between the shaft hole 103 and the valve stem 105 to the upper end side of the valve guide 104, The gas pressure is applied to the inclined surface 117 of the seal lip 112.

As a result, the seal lip 112 may open to the outer peripheral side and the contact surface pressure of the seal surface 116 may be reduced, impairing the function of controlling the amount of oil leakage in the head cover chamber 100.

Further, since the gas pressure acts as a force to lift the oil seal 109 as a whole upward, the oil seal 109 may be misaligned on the outer periphery of the valve guide 104 or may be removed. It was easy to do.

This invention is to solve the above-mentioned problems, and when the fluid pressure of the second fluid chamber rises and the fluid pressure is transmitted to the seal lip side through the shaft hole, The purpose is to provide an oil seal that can maintain the contact pressure of the.

Another object of the present invention is to provide an oil seal capable of preventing a pressure increase in the second fluid chamber from acting as a force in the direction of pulling on the seal lip of the oil seal.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention relates to a shaft inserted into a shaft hole of a partition wall that separates a first fluid chamber and a second fluid chamber, the shaft being on the first fluid chamber side and between the outer circumference of the shaft. A ring having a cylindrical portion set to an inner peripheral diameter that forms a space is fixed, and a seal ring is attached to the partition wall on the side of the first fluid chamber, and the seal ring is located at a position facing the space. A seal lip that contacts the inner peripheral surface of the cylindrical portion is formed.

[0013]

[Action]

 According to the present invention based on the above configuration, a certain amount of the fluid in the first fluid chamber reaches the space through the seal surface formed by the seal lip and the cylindrical portion, and enters the gap between the shaft and the shaft hole for lubrication. To do.

On the other hand, even if the fluid pressure in the second fluid chamber rises and the fluid pressure is transmitted to the space through the shaft hole, the fluid pressure is mainly in the radial direction with respect to the inner peripheral surface of the seal lip. Join.

[0015]

【Example】

 Next, the present invention will be described based on examples. FIG. 1 is a front half sectional view when the present invention is applied to a valve device of an automobile engine. A head cover chamber 1 serving as a first fluid chamber located above is separated from a port portion 2 serving as a second fluid chamber located below by a cylinder head 3 serving as a partition wall. A valve guide 5 having a shaft hole 4 in the up and down direction is attached to the cylinder head 3. The valve guide 5 is set to have a length protruding from the head cover chamber 1 to the port portion 2 by a predetermined amount. An annular groove 10 is provided on the outer peripheral surface of the valve guide 5 on the side of the head cover chamber 1.

A valve stem 6 is inserted into the shaft hole 4 as a shaft that can reciprocate in the vertical direction (arrow B), and a head 7 is provided at the lower end of the valve stem 6. A valve seat 9 is provided between the port 2 and the combustion chamber 8.

On the other hand, a sub-retainer 11 as a ring is fixed to the outer periphery of the valve stem 6 on the side of the head cover chamber 1. The sub-retainer 11 has a cylindrical small-diameter portion 12 fixed to the outer circumference of the valve stem 6, an outward flange 13 connected to the small-diameter portion 12, and an axial direction extending from the outward flange 13 to the cylinder head 3 side. And a large-diameter portion 14 as a flared cylindrical portion.

The sub-retainer 11 may be press-fitted and fixed to the outer periphery of the valve stem 6, or a male screw may be formed on the outer peripheral surface of the valve stem 6 and a female screw may be formed on the inner peripheral surface of the small diameter portion 12. Alternatively, it may be screwed up. The inner peripheral surface 15 of the large-diameter portion 14 is set to have an inner peripheral diameter E capable of forming an annular space D having a constant size with the outer periphery of the valve stem 6. The inner diameter E is uniform in the axial direction.

A seal ring 16 is attached to the head cover chamber 1 side of the valve guide 5. The seal ring 16 has a seal body 17 made of a rubber-like elastic body fitted and fixed to the outer periphery of the valve guide 5, and a metal ring 18.

A seal lip 19 extending axially upward is formed in the seal body 17 at a position facing the space D, and a lip tip on the outer peripheral side of the seal lip 19 is provided at a large diameter portion of the sub-retainer 11. The inner peripheral surface 15 of 14 is in contact with the inner peripheral surface 15 to form a sealing surface 20. A garter spring 21 is provided on the inner peripheral side of the seal lip 19. Therefore, the large diameter portion 14 is set to the inner peripheral diameter E so that a predetermined tightening margin can be obtained by the seal lip 19.

Furthermore, an annular protrusion 22 is formed on the inner peripheral surface of the seal body 17, and the protrusion 22 is recessed into the annular groove 10 of the valve guide 5.

The sub-retainer 11 is attached to the valve stem 6 after fitting the seal ring 16 and assembling the valve stem 6.

An annular spring receiver 23 is fixed to the upper end of the valve stem 6, and a valve spring 24 is attached between the spring receiver 23 and the cylinder head 3.

In the above structure, the valve stem 6 is pushed down by the swing arm (not shown) and descends, and rises by the elastic force of the valve spring 24 when the pressure on the swing arm is released. In this way, the reciprocating movement of the valve stem 6 opens and closes between the port portion 2 and the combustion chamber 8, and intake / exhaust of fluid, that is, high-temperature and high-pressure gas is performed.

On the other hand, in the head cover chamber 1, splashing oil from the valve spring 24 and splash oil due to rotation of a cam shaft (not shown) are mixed in a mist form, and a predetermined amount of oil is passed through the sealing surface 20. It reaches the space D and is further leaked to the valve guide 5 side. As a result, the sliding surface between the valve stem 6 and the valve guide 5 is lubricated.

When the gas pressure in the port section 2 rises, the gas pressure is transmitted to the space D via the shaft hole 4. This gas pressure pushes open against the inclined surface 25 facing the seal surface 20, that is, acts inward, but at the same time, acts on the inner circumference of the seal lip 19 radially outward, so that the seal surface 20 It is possible to maintain the surface contact pressure at a suitable value. Therefore, the function of controlling the amount of oil leakage of the head cover chamber 1 is ensured.

Further, as described above, the gas pressure is applied to the inner periphery of the seal lip 19, the inclined surface 25, the upper end surface, etc., but the force for lifting the seal ring 16 upward in the figure (the force for withdrawing from the valve guide 5). Does not work as Therefore, it is possible to secure a stable sealing property without the seal ring 16 being displaced in the axial direction on the outer periphery of the valve guide 5 or falling off.

[0028]

[Effect of the device]

 Since the present invention is configured as described above, even if the fluid pressure of the second fluid chamber rises and the fluid pressure is transmitted to the space through the shaft hole, the contact surface of the seal lip is The pressure can be maintained at an appropriate value. Therefore, the function of controlling the amount of fluid leakage in the first fluid chamber is ensured.

Further, although the gas pressure is applied to the entire seal lip, it is not applied in the direction in which the seal ring comes out of the mounting portion. Therefore, the seal ring is prevented from being displaced in the axial direction and the seal ring does not come off, and stable sealing performance can be secured.

[Brief description of drawings]

FIG. 1 is a front half sectional view showing an embodiment in which the present invention is applied as a valve stem seal of an engine.

FIG. 2 is a front half sectional view showing a conventional valve stem seal.

[Explanation of symbols]

 1 head cover chamber (first fluid chamber) 2 port section (second fluid chamber) 3 cylinder head (partition wall) 4 shaft hole 5 valve guide 6 valve stem (shaft) 7 head 8 combustion chamber 9 valve seat 10 annular groove 11 sub retainer ( Ring) 12 Small diameter portion 13 Outward flange 14 Large diameter portion (cylindrical portion) 15 Inner peripheral surface of large diameter portion 16 Seal ring 17 Seal body 18 Metal ring 19 Seal lip 20 Sealing surface 21 Garter spring 22 Annular protrusion 23 Spring receiver 24 Valve spring 25 Inclined surface B Reciprocating direction of valve stem D Space E Inner diameter of large diameter part

Claims (1)

[Claims for utility model registration] 1. A shaft inserted into a shaft hole of a partition wall separating the first fluid chamber and the second fluid chamber, the outer periphery of the shaft being on the side of the first fluid chamber. While fixing a ring having a cylindrical portion set to an inner peripheral diameter forming a space between the seal wall and the first fluid chamber side of the partition wall, a seal ring is attached to the seal ring and the space. An oil seal, characterized in that a seal lip is formed at a position facing the inner peripheral surface of the cylindrical portion.