| 摘要 |
PROBLEM TO BE SOLVED: To restrain reduction in a lift quantity of a needle valve according to reduction in a magnetostrictive quantity of a magnetostrictive element at temperature rise time. SOLUTION: The needle valve 2 is lifted by extending the magnetostrictive element 3 fixed to a fuel injection valve case 5, and a thermal expansion coefficient of the magnetostrictive element 3 and the needle valve 2 is decided by taking into consideration a reduction quantity of the magnetostrictive quantity of the magnetostrictive element 3 caused by a temperature rise. That is, the thermal expansion coefficient of the magnetostrictive element 3 and the needle valve 2 is decided so that the lift quantity of the needle valve 2 is not reduced even if the magnetostrictive quantity of the magnetostrictive element 3 reduces according to the temperature rise. For example, when the magnetostrictive element 3 and the needle valve 2 are arranged so that the lift quantity of the needle valve 2 increases as a thermal expansion quantity of the magnetostrictive element 3 increases and the lift quantity of the needle valve 2 reduces as a thermal expansion quantity of the needle valve 2 increases, the thermal expansion quantity of the needle valve 2 is set smaller than the thermal expansion quantity of the magnetostrictive element 3.
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