PURPOSE: To reduce pulsation of pressure in a pump, by stabilizing the internal leakage of pump at any angular position of a rotor through provision of leakage controlling grooves in contact surfaces between the rotor and side plates, and thereby preventing fluctuation of discharge quantity of the pump due to leakage of fluid inside the pump.
CONSTITUTION: When the discharge pressure of a pump is raised, pressure fluid in pressure grooves 37, 38 is leaked to annular leakage controlling grooves 40, 41 through a side clearance formed between a rotor 22 and side plates 15, 16 and then leaked radially toward suction ports 25, 26. In case that the angular range of leakage at the suction ports 25, 26 is small, the amount of fluid leaked from the suction ports 25, 26 to the leakage controlling grooves 40, 41 is increased. On the other hand, in case that the angular range of leakage is large, the amount of fluid leaked is decreased. Thus, since the amount of fluid leaked from the leakage controlling grooves 40, 41 to the suction ports 25, 26 is stabilized at any position of the rotor 22, fluctuation of discharge quantity due to leakage of fluid inside the pump can be minimized, so that pulsation of pressure can be reduced.
HAGA KIYOUSUKE
TANAKA TSUNEO
