To prevent leakage of brake fluid from a rotary type pump when a pressure at the suction port of the rotary type pump is increased to a high value.
A casing 50 incorporates outer and inner rotors 51 and 52 and has a central hole 50a in which a drive shaft 54 is fitted. The casing 50 is provided with ports 60 and 61 to suck and discharge brake fluid from and to the rotors 51 and 52 and a line J to guide leak oil in a central hole 50a to the outside of the casing 50 is provided. Oil leaking from the line J is returned to a spot situated upper stream from the rotary type pump. In this case, when a pressure in a spot situated upper stream from the rotary type pump is high, brake fluid is not returned, whereby a reservoir is provided to store brake fluid flowing through the line J. When a pressure in a spot situated upper stream from the rotary type pump is reduced to a low value, brake fluid is returned from the reservoir.
MORIKAWA TOSHIYA