JPH051608Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a valve stem seal used to control the amount of lubricating oil supplied to the sliding parts of intake and exhaust valves and valve guides of internal combustion engines. Regarding.

(Prior Art) In an internal combustion engine, an appropriate amount of lubrication is required between the valve stem and the valve guide of the intake and exhaust valves, which reciprocate through the valve guide, and is sufficient for effective lubrication but not excessive. Oil supply is required.

What is shown in FIG. 2 is an example of a valve stem seal disclosed in Japanese Utility Model Publication No. 47-24188 as a means for controlling the appropriate amount of lubricating oil supplied between the above-mentioned valve stem and valve guide.

The valve stem seal shown in the figure is made of a rubber-like elastic material, and has a cylindrical fixing part 3 embedded with a reinforcing ring having a substantially snake-eye shape at one end in the axial direction.
and a seal lip 4 extending from the cylindrical fixing part 3 and having a substantially cylindrical shape and a substantially arcuate cross-sectional shape.
and a sealing member 7 which is located on the side of the cylindrical fixing part 3 with respect to the sealing lip 4 and has an auxiliary sealing lip 5 having a substantially triangular cross-sectional shape and provided with a notch 6 protruding toward the inner circumferential side; The cylindrical fixing part 3 is attached to the valve guide 2, and the seal lip 4 and the auxiliary seal lip 5 are attached to the valve stem 1. The amount of lubricating oil fed into the gap between the valve stem 1 and the valve guide 2 is controlled by sliding it in elastic contact with the circumferential surface of the valve stem 1 and the valve guide 2.

The amount of lubricating oil in the valve stem seal according to the conventional description described above is controlled by the approach angle α on the inlet side, the approach angle β on the outlet side, and This is achieved by appropriately setting a notch 6 provided in the auxiliary seal lip 5 which has a rectangular cross-sectional shape.

(Problems to be Solved by the Invention) In the valve stem seal according to the prior art described above, the seal lip 4 is located at the end of the seal member 7, and the auxiliary seal lip 5 is made to have a triangular cross-sectional shape. As shown in Fig. 3, the edge part of the tip is formed so that it is easily crushed, so the gap between the valve stem 1 and the valve guide 2 causes eccentricity between the valve stem 1 and the valve guide 2. When this condition occurs, the tip of the auxiliary seal lip 5 is crushed by the circumferential surface of the valve stem 1 and the cylindrical fixing portion 3 side of the seal member 7 remains concentric with the valve guide 2, whereas the seal lip 4 is pressed against the circumferential surface of the valve stem 1 and maintains a concentric state with respect to the valve stem 1, the seal member 7 becomes inclined with respect to the valve stem 1, and as a result, the approach angle of the inlet side of the seal lip 4 is changed. Since α and the approach angle β on the exit side change, there is a great possibility that the set control function for the amount of lubricating oil will not be maintained.

The present invention presents a structure of a valve stem seal that can maintain an appropriate lubricant amount control function by suppressing the inclination of the seal member with respect to the valve stem due to the eccentricity that occurs between the valve stem and the valve guide. The purpose is to

(Means for Solving the Problems) In consideration of the problems with the valve stem seals according to the conventional technology described above, the present invention provides a cylindrical fixing part that is attached to a valve guide into which a valve stem is inserted, and A substantially cylindrical sealing member made of a rubber-like elastic material is integrally fixed to a joint provided at one end in the axial direction of the cylindrical fixing portion, and a substantially arc-shaped cross-sectional shape provided near the tip of the sealing member. The valve stem seal has a seal lip that is in elastic contact with the circumferential surface of the valve stem, wherein the inner circumferential surface of the seal member located between the seal lip and the joint portion has a substantially circular cross-sectional shape; The structure includes an annular protrusion that makes elastic contact with the circumferential surface of the stem.

The above-mentioned annular protrusion has a cross-sectional radius as large as possible in order to widen the contact width with the circumferential surface of the valve stem, and the tip of the annular protrusion is filled with lubricating oil controlled by a seal lip. An axial groove is provided as necessary for the passage of the material.

(Function) The valve stem seal according to the present invention having the above configuration has a substantially cylindrical shape, and is attached with a seal lip that slides on the circumferential surface of the valve stem to control the amount of lubricating oil supplied. An annular protrusion that is disposed on the cylindrical fixed part side of the sealing member joined to the fixed part, has a circular cross-sectional shape, and comes into elastic contact with the circumferential surface of the valve stem, causing eccentricity between the valve stem and the valve guide. When the seal lip is pressed against the circumferential surface of the valve stem, the center axis of the seal member is kept parallel to the center axis of the valve stem, and the approach angles on the inlet and outlet sides of the seal lip are maintained at the set values. let it happen

(Embodiment) In the embodiment shown in FIG. 1, the inner circumferential side of a reinforcing ring having a substantially cylindrical shape is coated with a rubber-like elastic material, and the cylindrical fixing part 3 attached to the valve guide 2 is A sealing member 7 made of a rubber-like elastic material and having a substantially cylindrical shape is connected to the end,
On the inner circumferential side of the seal member 7, there is a seal lip 4 having an arcuate cross-sectional shape and elastically contacting the circumferential surface of the valve stem 1 to form an approach angle α on the inlet side and an approach angle β on the outlet side, and a circular cross-section. The seal member 7 is provided with an annular protrusion 10 which is located between the seal lip 4 and the cylindrical fixing part 3, has a plurality of axial grooves 11, and comes into elastic contact with the circumferential surface of the valve stem 1. A garter spring 8 that biases the seal member 7 inward in the radial direction is attached to the outer circumferential side of the seal member 7 .

In the illustrated embodiment, when the valve stem 1 moves to the left in the figure with respect to the valve guide 2,
As shown by dotted lines in the figure, the annular protrusion 10 and the seal lip 4 are pushed by the circumferential surface of the valve stem 1 and move to the left in the figure. 1, the approach angle α on the inlet side and the approach angle β on the outlet side formed at the front and rear of the seal lip 4 in the axial direction are kept unchanged.

(Effect of the invention) A cylindrical fixing part attached to a valve guide into which a valve stem is inserted, and a substantially cylindrical rubber-like part integrally fixed to a joint provided at one end in the axial direction of the cylindrical fixing part. A valve stem seal having a sealing member made of an elastic material and a sealing lip having a substantially arcuate cross-sectional shape provided near a distal end of the sealing member and making elastic contact with the circumferential surface of the valve stem, wherein the sealing lip and the joining The inner circumferential surface of the seal member located midway between the valve stem and the valve stem is provided with an annular protrusion that has a substantially circular cross-sectional shape and comes into elastic contact with the circumferential surface of the valve stem. When the annular protrusion and seal lip are pushed by the circumferential surface of the valve stem and move due to the eccentricity that occurs between the valve guides, they both move approximately parallel to the valve stem, so the seal lip moves back and forth in the axial direction. Since the formed approach angle on the inlet side and the approach angle on the outlet side are kept unchanged, the amount of lubricating oil supplied can maintain the set value.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an embodiment of the present invention, Fig. 2 is a cross-sectional view of an example of a valve stem seal according to the prior art, and Fig. 3 is a cross-sectional view showing the situation in which a malfunction occurs in the same example. be. 1... Valve stem, 2... Valve guide, 3
...Cylindrical fixing part, 4...Seal lip, 5...
Auxiliary seal lip, 6... Notch, 7... Seal member, 8... Garter spring, 10... Annular projection, 11... Axial groove.

Claims (1)

[Scope of utility model registration request] A cylindrical fixing part 3 attached to the valve guide 2 into which the valve stem 1 is inserted, and the cylindrical fixing part 3
a substantially cylindrical seal member made of a rubber-like elastic material and integrally fixed to a joint portion 9 provided at one end in the axial direction;
In the valve stem seal, the seal lip 4 has a substantially arcuate cross-sectional shape and is provided near the tip of the seal member and comes into elastic contact with the circumferential surface of the valve stem 1. A valve stem seal characterized in that an annular protrusion 10 having a substantially circular cross-sectional shape and in elastic contact with the circumferential surface of the valve stem 1 is attached to the inner circumferential surface of the seal member located in the middle.