| 摘要 |
<p>A valve stem seal 10 provides an elastomeric main valve body having an upper working portion 14 and a lower support portion 16, the latter for support of the seal on a valve guide member 12. The seal 10 contains a central helically threaded internal region 18 adapted to meter oil flow between the valve guid 12 and a valve stem reciprocally moveable with the guide. The upper working portion 14 defines a pair of ends, wherein each end contains a non-threaded internal portion 26, 28 defining a plurality of alternately arranged axially extending grooves 32 and ribs 30. The grooves 32 provide oil flow passageways, while the ribs 30 support the ends of the working portion against the reciprocal valve stem member. In a preferred form, the non-threaded internal portions 26, 28 have axial lengths within a range of one-tenth to one-third the axial length of the central threaded region 18.</p> |
