| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston ring for generating tensile force suitable for a low speed and low load state and a high speed and high load state, concretely, to provide a piston ring using a coil expander that can be gradually changed depending on temperature changes of an internal combustion engine in the temperature range from 100 to 200°C and is excellent in cost performance compared with shape memory alloy. SOLUTION: The piston ring is constituted of a piston ring body and the coil expander arranged on an inner circumferential side of the piston ring body. The coil expander is formed of a bimetal member made by jointing two kinds of metals different in expansion coefficient. COPYRIGHT: (C)2004,JPO
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