| 摘要 |
A valve stem seal (1) installed for sealing an annular space (4) between a valve guide (2) having one end facing a cam side (A) and the other end facing a cylinder side (B), and a valve stem (3) coaxially arranged in an inner peripheral side of the valve guide (2) so as to reciprocate therein, whereby the valve stem seal (1) is provided with a reinforcing ring (10) fitted to the valve guide (2) and having a radially extending portion (12), a main seal lip (41) slidably brought into close contact with the valve stem (3) and extending toward the cam side (A), and a back pressure projection (50) positioned on the cylinder side (B) rather than the main seal lip (41), extending in a radial direction and slidably brought into close contact with the valve stem (3), and a leading end portion (51) of the back pressure projection (50) has a predetermined distance in an axial direction between it and the radially extending portion (12). |
