| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve stem seal which can prevent an increase of slide resistance to a valve stem based on back pressure while reducing the back pressure which is applied on a seal lip.SOLUTION: A valve stem seal 1 comprises an annular reinforcing ring 10 with an axial line x as a center, and an annular elastic body part 20 which is formed of an elastic body with the axial line x as a center. A seal part 21 of the elastic body part 20 has a seal base part 23, a seal lip 24 abutting on the valve stem 52, an annular back pressure lip 25 which is arranged in an axial line x direction while separating from the seal lip 24, and an annular protrusion 26 which is arranged in the axial line x direction between the seal lip 24 and the back pressure lip 25. At least one back pressure lip groove 30 which penetrates the back pressure lip 25 in the axial line x direction is formed at the back part lip 25, and at least one protrusive groove 26a which penetrates the protrusion 26 in the axial line x direction is formed at the protrusion 26.SELECTED DRAWING: Figure 1 |
