| 摘要 |
PROBLEM TO BE SOLVED: To prevent the wear of a sliding part by forming a downward inclined tongue piece provided in the part of the inner peripheral surface of a seal part lower than its contact part with a stem, the seal part being provided the upper half part of a stem seal of an engine valve, such that a tip inner peripheral edge of the tongue piece is always in contact with the outer peripheral surface of the stem. SOLUTION: A stem seal 14 is composed of a metallic cylindrical part 14a pressure-inserted into the upper end part of a valve guide 2 and a seal part 14b integrally provided therewith, and a double-annular projecting part 14c formed in the upper end inner surface of the seal part 14b contacted with the outer peripheral surface of the stem 3a of an engine valve 3. An annular tongue 15 to be bent vertically is formed directly below the annular projecting part 14c on the lower side of the center inner peripheral surface of the seal part 14b. This tongue piece 15 is continuously provided toward the center of the stem 3a downward slantingly and its tip inner peripheral edge is always placed in contact with the outer peripheral surface of the stem 3a. Thus, the leakage of exhaust gas to the outside from the stem seal when a pressure is increased in an exhaust port is prevented. |
