To arrange a resonance room for reducing the pulse of a low frequency and an expansion room resonance room for reducing the pulse frequency in a comparatively wide range commonly without enlarging an entire structure by that the resonance room can be constituted in a small shape.
A cylindrical casting 6 is closed by a cover 7 after the insertion of a sleeve 8. Expansion rooms 86, 66 are formed by the recessed part 81 of the sleeve 8 and the right side cylindrical space of the casing 6. A through hole for communicating partition wall with an oil passage 82 and a groove 83 is installed on one part of the groove 83 of the sleeve 8 and a resonance room is formed by the space surrounded by the groove 83 and the inner surface of the casing 6. As the resonance room is a shape running along the groove 83, a long resonance room can be formed without enlarging an entire constitution, Therefore, the resonance room of a low decreasing frequency and the expansion room of the decreasing frequency with a wide area can be constituted compactly.
GOTO YASUHARU
MOTOSAWA YUKIHIRO
YUASA KAZUMASA
NAKAMURA SHIGETAKA
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