To reduce generation of noise in association with release of a filing space effectively by surely releasing the filing space by gear pair engaged with each other in a plurality of gear chamber to a suction side at an appropriate timing just after filling of a fluid.
In the inside of one gear chamber, a filling space S decisively generated by a relief groove extending from a suction side and a communicating groove extending from a discharging side, is communicated with the relief groove 7 formed in a same way in the other gear chamber by the opening timing of a penetrating hole 9 formed including the top end part of the relief groove 7 in a parts in a space between the gear 3a of a driving gear 3 and the gear 4a of a driven gear 4. A fluid in a filling space S is released to the suction side so as to reduce generation of noise in association with the release.
OBATA YOSHIFUMI
IIDA TOSHIO
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