JPH0241409Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a valve stem seal having a fluorine resin film on the inner periphery of the lip, and particularly to improvements in the fluorine resin film.

``Prior art: Problems that cannot be solved by invention'' Conventionally, valve stem seals that integrate a fluorine resin film on the inner circumference of the lip are known, but when changing the amount of oil leaking at the lip contact surface, Specifications such as the thickness of the fluorine resin film and the shape and dimensions of the lip must be changed each time, and the design of the molding mold must be changed each time, which increases manufacturing costs. There were also problems such as complicated manufacturing management.

"Means for solving the problem" This invention aims to solve the above-mentioned conventional problem.
By providing multiple grooves at predetermined intervals in the circumferential direction from the vicinity of the contact surface to the lower part of the fluorine resin membrane, the amount of oil leaking from the valve stem seal can be adjusted as desired by simply changing the number and width of the grooves. When drawing the fluororesin membrane, a required cut is made in advance in the mold according to the change in the amount of leakage, and the drawing process is performed by forming the required notch in advance to change the valve stem seal. It is possible to manufacture valve stem seals with different oil leakage performance by simply changing the drawing mold for an inexpensive fluororesin membrane without changing the molding mold.

``Example'' Below, an example of this invention shown in the drawings will be described. The seal lip 2 has a fluorine resin film 3 on the inner periphery of the flange piece 1a of the annular reinforcing ring 1.
are burned into one piece.

This fluorine resin film 3 is provided with a plurality of grooves 4 vertically formed at predetermined intervals in the circumferential direction so that the tip thereof slightly touches the lower end of the contact surface 3' on the inner periphery. There is.

Therefore, when such a valve stem seal is used, a small amount of oil leaks through the grooves 4, and as the number of grooves 4 increases and the width thereof increases, the amount of oil leaking from the contact surface 3' increases. By appropriately changing the number and width of the grooves 4, the amount of oil leakage can be adjusted as appropriate.

When molding this fluorine resin film 3, the required number of mold grooves 6 are formed in the upper mold 5 of the molding die, and the fluorine resin sheet is formed into a circular shape by the upper mold 5 and the lower mold 7. A large number of prototypes of the fluororesin film 3 are drawn into the mold grooves 6 of the upper die 5 to form the grooves 4 by drawing them into protrusions, and these prototypes are cut out to form molds for valve stem seals. After the molding, the upper end of the molded product is cut off in the direction of the arrow in FIG. 3 to form a valve stem seal with an annular fluororesin film 3 baked on the inner periphery.

Therefore, by creating a mold in which the number or width of the mold grooves 6 of the upper mold 5 for forming the grooves 4 is changed in accordance with the design change of the oil leakage performance of the valve stem seal, the drawing mold for the valve stem seal can be changed. It is possible to mold the fluorine resin film 3 that is suitable for the desired oil leakage performance without changing the film itself.

``Effect of the invention'' As described above, according to this invention, a plurality of grooves are formed vertically downward from near the contact surface at predetermined intervals in the circumferential direction in the annular fluororesin film integrated on the inner circumference of the lip. Since they are placed in parallel, a small amount of oil leaks through the grooves, and as the number of grooves increases and the width of the grooves increases, the amount of oil leaking from the contact surface can increase. By appropriately changing the width, the amount of oil leakage can be adjusted as appropriate.

Therefore, when molding bell stem seals with different amounts of oil leakage, it is recommended to use an inexpensive mold for drawing and molding fluorine resin membranes that has a different number and width of mold grooves for forming grooves in the fluorine resin membrane. It is possible to manufacture the valve stem seal without creating a new expensive mold for molding the valve stem seal, and it is possible to reduce manufacturing costs and simplify manufacturing management.

[Brief explanation of the drawing]

Fig. 1 is a partial longitudinal sectional front view showing an embodiment of this invention, Fig. 2 is a cross-sectional plan view showing the drawing state of the fluororesin membrane according to this invention, and Fig. 3 is the molding of the valve stem seal of this invention. It is a vertical front view showing a state. 2... Lip, 3... Fluorine resin film, 3'...
Contact surface, 4... groove.

Claims (1)

[Scope of utility model registration request] The inner periphery of the lip is characterized by having a plurality of grooves arranged at predetermined intervals in the circumferential direction downward from the vicinity of the contact surface of the annular fluorine resin film integrated into the inner periphery of the lip. Valve stem seal with resin membrane.