JPS5930888B2 - valve stem seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve stem seal, and more particularly to a highly durable valve stem seal.

A sealing lip made of a rubber-like elastic material fixed to a valve guide that guides the reciprocating movement of an intake or exhaust valve of an internal combustion engine and attached radially inward is brought into appropriate sliding contact with the circumferential surface of the valve stem, A valve stem seal is known that is designed to supply an appropriate amount of lubricating oil to the sliding parts of a valve guide and a valve stem.

Figure 1 shows an example of this type of valve stem seal, in which a valve guide 2 guides the reciprocating movement of the valve stem 1.
A sealing piece 6 made of a rubber-like elastic material attached to the end of the cylindrical part 4 that is inserted and held at the end extends approximately in the axial direction, and a sealing lip 7 is formed inside the sealing piece 6. is in contact with the circumferential surface of the valve stem 1 and allows an appropriate amount of lubricating oil supplied from above in the figure to pass through and be sent to the sliding contact portion between the valve stem 1 and the valve guide 2.

The amount of lubricating oil passing through the contact area between the seal lip 7 and the valve stem 1 per unit time is determined by the angles α and β (the first It is known that the amount can be controlled appropriately by setting the radius of curvature R of the cross-sectional shape of the tip of the seal lip 1 to an appropriate value.

However, with this type of valve stem seal, as the engine operates, the sliding part of the seal lip and the valve stem circumferential surface wears and deforms, causing an excessive amount of lubricating oil to be pumped in. The problem remains.

From the experimental results, we found that the amount of lubricant fed changes as the wear progresses at the tip of the seal lip, as shown in Figure 2. Furthermore, it has been found that the relationship between the surface roughness of the valve stem circumferential surface and the amount of wear on the seal lip is as shown in FIG.

Therefore, the rougher the surface roughness of the circumferential surface of the valve stem, the more quickly the amount of lubricating oil fed will decrease the durability of the valve stem seal, which is not preferable.

It is possible to improve the durability of the valve stem seal by reducing the surface roughness of the valve stem periphery by means such as puff finishing, but this method increases the processing cost of the valve stem, so it is not the preferred method. It's hard to say.

On the other hand, as shown in Table 1, it was found that the surface roughness of the peripheral surface of the valve stem after operation for a certain period of time was considerably smaller than before the start of operation.

Focusing on the above points, the present invention attaches an auxiliary ring near the seal lip of a valve stem seal, whose inner diameter in a free state is slightly smaller than the inner diameter of the seal lip. The surface roughness of the valve stem periphery is reduced by the sliding between the auxiliary ring and the valve stem periphery, and the inner periphery of the auxiliary ring is worn out, causing the seal lip to slide against the valve stem periphery, allowing an appropriate amount of lubricating oil to be released. By feeding the valve stem, the life of the valve stem is extended.

The auxiliary ring is mounted on either or both of the lubricating oil supply source side and the sliding part side of the valve stem and valve guide in the axial direction with respect to the seal lip, and the auxiliary ring is shaped like a thin plate material. The shape of the scraper, the shape of the wiper with a roughly arc-shaped cross section, the shape of a wide ring with a cylindrical inner circumferential surface, etc. are appropriately selected, and the inner diameter of the auxiliary link is smaller than the inner diameter of the seal lip. At the beginning of operation, the cross-sectional shape of the auxiliary link is lubricated to prevent lubricant from being blocked at the contact area between the auxiliary ring and the valve stem and not reaching the sliding area between the valve stem and the valve guide. Means are used, such as creating a shape that allows oil to be easily sucked in, or providing appropriate slits on the inner peripheral side of the auxiliary ring so that lubricating oil can pass through the slits.

The material for the auxiliary ring is one that can elastically contact and slide on the circumferential surface of the valve stem to smooth the surface, such as thin metal plates, synthetic resin materials, rubber-like elastic materials, porous materials, etc. Therefore, it is effective to mix an abrasive into the above-mentioned synthetic resin material, rubber-like elastic material, porous material, etc. as a means to help reduce surface roughness due to wear on the peripheral surface of the valve stem.

Embodiments of the present invention will be described below with reference to the drawings.

In the embodiments shown in FIGS. 4 and 5, the auxiliary ring 10 is made of bronze.
Manufactured using metal plates such as brass or heat-resistant resin materials,
The inner end of the radial portion extending inward from one end of the cylindrical mounting portion 12 has a truncated conical shape and constitutes a scraper 13. As the valve stem 1 reciprocates, the scraper 13 Friction is applied to the valve stem circumferential surface to reduce its surface roughness.

Slits 14 arranged on the circumference are cut inside the scraper 13 so that lubricating oil can be easily sent to the valve guide 2 side.

It is preferable that the scraper 13 is positioned as close to the seal lip 1 in the axial direction as possible.

In the illustrated embodiment, the auxiliary ring 10 is provided on the lubricating oil supply source side (upper part of the figure) with respect to the seal lip 7, but it may also be provided on the valve guide 2 side, or it may be provided on both sides. It is even more effective.

In the embodiment shown in FIG. 6, the auxiliary ring 10 is made of a heat-resistant synthetic resin material, a heat-resistant rubber material, etc., and has a substantially cylindrical outer circumferential surface that fits the inner circumferential surface of the valve stem seal. It has a wiper shape with a sliding lip 16 having a substantially arc-shaped cross section on the inner peripheral surface, and the sliding lip 16 is configured to rub against the peripheral surface of the valve stem 1 to reduce its surface roughness. The cross-sectional shape of the sliding lip 16 is approximately arc-shaped, or the slits 14 are arranged circumferentially on the sliding lip 16, so that the lubricating oil flows between the sliding lip 16 and the valve. It passes through the contact part of the stem 1 and is fed into the valve guide 2.

By mixing an abrasive when creating the auxiliary ring 10, the surface roughness of the valve stem circumferential surface can be reduced more quickly and effectively.

In the embodiment shown in FIG. 7, the auxiliary ring 10 is made of a heat-resistant synthetic resin material, a heat-resistant rubber material, etc., and its outer circumferential surface is fitted into the inner circumferential surface of the valve stem seal, and the auxiliary ring 10 is expanded in the radial direction. The flange portion 18 is mounted between the valve stem seal and the end face of the valve guide 2, and the sliding lip 16 forms a wide cylindrical inner circumferential surface extending in the axial direction. It slides on the circumferential surface of the valve stem and reduces its surface roughness.

In order to assist the suction of lubricating oil at the contact area between the sliding lip 16 and the valve stem 1, the cross-sectional shape of the end of the sliding lip 16 may be made into an arc shape, a slit may be provided on the inner circumferential side, or an auxiliary ring may be used. Measures such as mixing an abrasive during manufacture are taken in the same manner as in the embodiment shown in FIG.

Since the inner circumferential surface of the sliding lip 16 has a cylindrical shape and the area in contact with the valve stem 1 is wide, if a porous material is used for the auxiliary ring 10, the sliding lip 16 can sufficiently retain lubricating oil. This ensures smooth sliding with the valve stem circumferential surface.

In the embodiment shown in FIG. 8, the same material as the seal part 6 of the valve stem seal is used for the auxiliary ring.
It is manufactured to be integrated with the sliding lip 16.
The inner diameter of the sliding lip 16 is made smaller than that of the seal lip 7, and the cross-sectional shape of the sliding lip 16 is made into an arc shape, as in the above-described embodiment, in order to facilitate the suction of lubricating oil. , measures such as providing slits on the inner circumferential surface are taken.

In the illustrated embodiment, the sliding lip 16 is shown to be located on the axial valve guide 2 side with respect to the sealing lip 1, but it may be provided on the lubricating oil supply source side or on both sides. is also possible.

Since the valve stem seal of the present invention has the above-described structural requirements, the following effects are brought about.

A sliding lip 16 having an inner diameter smaller than that of the seal lip °7 is disposed near the seal lip 7 that regulates the amount of lubricating oil supplied to the sliding portion between the valve stem and the valve guide. , the circumferential surface of the valve stem 1 is rubbed by the sliding lip 16 at the beginning of engine operation, and its surface roughness is reduced, so that the engine operation is improved compared to the prior art valve stem seal that does not have a sliding lip. The valve stem can maintain its function for a long period of time without the problem of an excessive amount of lubricating oil being fed due to wear of the seal lip due to this.

The material, shape, mounting position, number of mounting rings, etc. of the auxiliary ring can be appropriately selected depending on the environmental conditions during operation, the structure of the engine, etc., and those having the structures shown in the above-mentioned embodiments may be combined with each other. It is also possible.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a valve stem seal according to the prior art;
Figure 2 is a graph showing the increase in the amount of lubricating oil fed as the amount of wear on the seal lip increases, and Figure 3 is a graph showing the increase in the amount of lubricant fed as the amount of wear on the seal lip increases. Graphs showing the state of wear, Figures 4 and 6
7 and 8 are longitudinal cross-sectional views of one embodiment of the present invention, and FIG. 5 is an auxiliary ring 1 shown in the embodiment of FIG. 4.
FIG. DESCRIPTION OF SYMBOLS 1... Valve stem, 2... Palfkide, 4... Cylindrical part, 6... Seal piece, 7... Seal lip, 10...Auxiliary ring, 12...Mounting part, 13...
Scraper, 14...Slit, 16...
...Sliding lip, 18...Brim part.

Claims (1)

[Scope of Claims] 1. The seal lip 7 is fixed to the valve guide 2 side and slides on the circumferential surface of the valve stem 1, and has a smaller inner diameter, and is located near the seal lip T and the seal lip 7. With respect to the lip 7, an auxiliary ring 10 made of an elastic material is disposed on the axial side of the lubricating oil supply source and on the opposite side of the lubricating oil supply source in the axial direction (both are disposed on one side and slide on the circumferential surface of the valve stem 1). 2. The valve stem seal according to claim 1, wherein the auxiliary ring 10 has a scraper shape. 3. The valve stem seal according to claim 1, wherein the auxiliary ring 10 has a wiper shape. The valve stem seal according to claim 1.4 The valve stem seal according to claim 1, wherein the auxiliary ring 10 is cylindrical and has a rectangular ring shape with a wide inner peripheral surface.5 The auxiliary ring 10 The valve stem seal according to claim 2, 3 or 4, comprising a slit running in the axial direction on the inner circumferential surface.6 The inner circumferential sliding portion of the auxiliary ring 10 has a substantially arc-shaped Claim 3 or 4 includes a portion showing a cross-sectional shape of
Valve stem seals as described in section. 1. The valve stem seal according to claim 1, wherein the seal lip 1 does not come into direct contact with the circumferential surface of the valve stem 1 at the beginning of engine operation. 8. The valve stem seal according to claim 1, 3, or 4, wherein the material of the auxiliary ring 10 is a heat-resistant synthetic resin material or a heat-resistant rubber material. 9. The valve stem seal according to claim 1, 3, or 4, wherein the auxiliary ring 10 contains an abrasive. 10. The valve stem seal according to claim 4, wherein the material of the auxiliary ring 10 is porous. 11. The valve stem seal according to claim 1, wherein the auxiliary ring 10 is made of the same material as the seal piece 6.