| 摘要 |
In order to prevent an increase in the sliding resistance with respect to an outer circumferential surface of a valve stem (104) due to back pressure and to improve the operability of the valve stem (104), this valve stem seal is provided with: a base part (11) reinforced by a reinforcing ring (15) and mounted on the outer circumference of a valve guide (105); a neck part (12) positioned more adjacent to the side of an oil chamber (109) than the valve guide (105) and extending from the base part (11) toward the inner diameter side of an end section of the oil chamber (109) side of the reinforcing ring (15); a main lip (13) extending from the inner diameter side of the neck part (12) toward the oil chamber (109) side and slidably contacting the valve stem (104); and a back pressure lip (14) extending from the inner diameter side of the neck part (12) toward the valve guide (105) side, wherein the neck part (12) has a lower bending stiffness than the portion from the back pressure lip (14) to the waist section of the main lip (13), and the back pressure lip (14) slidably contacts the valve stem (104) by means of the back pressure and does not contact the valve stem (104) when there is no back pressure load. |
