Abstract: A fluid pump includes a housing, a rotary shaft, and pump units which are contained in the housing and sucks in, pressurizes, and discharges fluid with being rotationally driven by the rotary shaft. The housing has a suction passage conducting the fluid from a suction port to the pump unit, a discharge passage conducting the fluid from the pump unit to a discharge port, a return passage returning a portion of the fluid flowing through the discharge passage to an upstream side of the pump unit, and a control valve controlling a flow of the returned fluid. The return passage is formed so as to conduct the returned fluid in the same direction as a flow of a sucked fluid flowing through the suction passage to make the returned fluid flow together with the sucked fluid.

Abstract: An air ejection port for ejecting air-mixed oil is structured with a first air ejection port provided on the inner peripheral side from an inscribed circle of an outer rotor and a second air ejection port provided on the outer peripheral side from a circumscribed circle of the inner rotor, the air ejection port can have an enlarged port area as the total of area of the first air ejection port and area of the second air ejection port in a state without being in communication with either of a suction port and a discharge port, and a disadvantage that a pump chamber of a previous stroke and a pump chamber of a subsequent stroke communicate with each other through the air ejection port can be avoided.

Abstract: An air ejection port for ejecting air-mixed oil is structured with a first air ejection port provided on the inner peripheral side from an inscribed circle of an outer rotor and a second air ejection port provided on the outer peripheral side from a circumscribed circle of the inner rotor, the air ejection port can have an enlarged port area as the total of area of the first air ejection port and area of the second air ejection port in a state without being in communication with either of a suction port and a discharge port, and a disadvantage that a pump chamber of a previous stroke and a pump chamber of a subsequent stroke communicate with each other through the air ejection port can be avoided.

Abstract: A fluid pump includes a housing, a rotary shaft, and pump units which are contained in the housing and sucks in, pressurizes, and discharges fluid with being rotationally driven by the rotary shaft. The housing has a suction passage conducting the fluid from a suction port to the pump unit, a discharge passage conducting the fluid from the pump unit to a discharge port, a return passage returning a portion of the fluid flowing through the discharge passage to an upstream side of the pump unit, and a control valve controlling a flow of the returned fluid. The return passage is formed so as to conduct the returned fluid in the same direction as a flow of a sucked fluid flowing through the suction passage to make the returned fluid flow together with the sucked fluid.