JPH021447Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a valve stem seal used in a valve part of an internal combustion engine, and more specifically, to an improvement of a metal cylinder having a flange part that fits into a valve guide. be.

Conventional valve stem oil seals are used in the valve stem of internal combustion engines, and as shown in Figure 1, they are devices for adjusting the flow rate of lubricating oil required by the sliding part between the valve stem 4 and the valve guide 3. Then, an elastic body B having a seal lip 1 that contacts the valve stem 4 above the upper end of the metal cylinder A to be fitted into the valve guide 3 is bonded to the metal cylinder A. It had an integrated structure. Most of the metal cylinders A used in this valve stem seal have an inward flange portion 2 at the top, as shown in FIG.
In many cases, the elastic body B is shaped to wrap around the flange portion 2 for the purpose of strengthening adhesive force and sealing force.

When installing a valve stem seal of this shape, unless the valve stem seal has a complicated cylindrical shape or the amount of pushing is regulated using a special jig, simply contact the lower end surface of the elastic body B of the valve stem seal with the upper end surface of the valve guide 3. In this case, the lower end surface of the elastic body B undergoes considerable elastic deformation. This deformation necessarily affects the seal lip 1 because the elastic body B is connected to the seal lip 1.
There was a great risk of weakening the sealing performance, such as by changing the shape of the seal lip 1 which reduced the tension force.

The present invention was made to solve these drawbacks at a low cost, and is an epoch-making invention that greatly improves the stability of sealing performance with a simple structure.

As shown in FIG. 2, the present invention includes a metal cylinder A having an inward flange part 2 at its upper part, and a metal cylinder A that includes the flange part 2 above and makes sliding contact with a valve stem 4. A valve stem seal is integrated with an elastic body B having a seal lip 1; the inner peripheral edge of the flange portion 2 on the upper part of the metal cylinder A is bent downward to form a bent portion 5 on the flange portion 2. This is the structure of the valve stem seal.

This structure provides the following excellent effects.

That is, as shown in FIG. 2, the lower end surface of the elastic body B and the upper end surface of the valve guide 3 of the installed valve stem seal are in contact with each other, and due to this contact, the lower end surface of the flange portion 2 of the metal cylindrical body A is Elastic body B1 located
Try to transform it horizontally. However, at this time, the inner circumferential edge 5 of the flange portion 2 is bent downward to wrap around the elastic body B1 located below the flange portion 2, so the elastic body B1 at the bottom of the flange portion 2 is compressed and is about to flow sideways. The elastic deformation is not transmitted outward from the inner circumferential edge 5 of the flange. In other words, the deformation occurring at the lower end surface of the elastic body B is suppressed only to that portion by the dam effect of the bent portion 5, and does not have the slightest influence on the seal lip 1 located above. If it is bent upward, the radial effect of the seal lip 1 will be impaired, resulting in a reduction in the sealing effect. Furthermore, since the bent portion 5 protrudes downward, it also serves as a stopper to stop insertion, and therefore, even if the pressing force for inserting it into the valve guide 3 is not constant, it is always installed at a fixed position and its adhesion force is also maintained. Equalized.

Furthermore, in order to improve the sealing effect, if a protruding ring 6 is provided on the lower end surface of the elastic body B1 below the flange portion 2 as shown in FIG. When they come into contact, a large amount of deformation occurs and the deformation is transmitted to the other side, but the bent portion 5 exhibits the same deformation blocking effect as described above, resulting in a higher sealing force. Furthermore, since the bending is performed at the two ends of the flange portion of the metal cylindrical body A, the bending process is easy and the above-mentioned excellent effects are achieved without increasing the cost significantly.

As explained above, the present invention is an inexpensive and ideal valve stem seal that allows the seal lip 1 to perform its original function without being influenced by other parts, and exhibits good fitability and strong sealing force for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional valve stem seal. FIG. 2 is a sectional view showing an embodiment of the valve stem seal of the present invention. FIG. 3 is an enlarged partial sectional view showing another embodiment of the valve stem seal of the present invention. A...Metal cylindrical body, B...Elastic body, 1...Seal lip, 2...Flange portion, 3...Valve guide, 4...Valve stem, 5...Bending portion.

Claims (1)

[Scope of utility model registration request] A valve stem seal in which a metal cylindrical body having an inward flange on its upper part and an elastic body having a seal lip above the metal cylindrical body that includes the flange and makes sliding contact with the valve stem are integrated. WHEREIN: A valve stem seal characterized in that an inner peripheral edge of the flange portion of the upper part of the metal cylinder body is provided with a bent portion facing downward.