The invention discloses a circular inside-release
oil pump composed of a pump body, a rotor pair, a pressure limiting valve, a spring, an end plug, a seal ring and a pump cap. The pump body is provided with an oil inlet, an oil outlet, a pressure limiting hole, an inside-release oil channel, an oil-in chamber, an oil-out chamber, a rotor hole, a rotor shaft hole, a main mounting hole, a locating hole, a side mounting hole and a
flange hole. The pressure limiting valve, the spring, the seal ring and the end plug are sleeved with the pressure limiting hole, the break-off side of the pressure limiting hole is provided with an oil release hole and an oil drainage hole which communicate with the inside-release oil channel, a circle is disposed between the oil release hole and the oil drainage hole. The rotor pair is sleeved with the rotor hole and the rotor shaft hole, the pump cap is fixed to the pump body, and a clearance fit is provided between the pump body and the rotor pair. The rotor rotates
clockwise in the rotor pair, oil is taken in from the oil inlet and drained from the oil
discharge hole. When the oil drainage pressure is higher than a set value, surplus oil will release to the oil-in chamber through the pressure limiting valve and the inside-release oil channel. Compared with the prior art, the circular inside-release
oil pump is large in output volume of
unit volume, simple in structure, high in
volumetric efficiency, reliable and stable in performance and long in service life.