Patent ID: 8807964

Claim:
A rotor-type variable oil pump configured to vary a pressure and output the pressure according to an engine RPM, said oil pump ( 100 ) comprising: a cylinder ( 130 ) connected to an outlet pipe ( 120 ) and having a first input pipe ( 133 a ) and a second input pipe ( 133 b ) branched from the outlet pipe ( 120 ), and a first output pipe ( 134 a ) and a second output pipe ( 134 b ) branched from an inlet side ( 110 ), a plunger ( 140 ) having a first pipe line ( 143 a ) and a second pipe line ( 143 b ) installed in the cylinder ( 130 ) and configured in a way such that one end of the plunger is exposed in the outlet pipe ( 120 ) while the other end is elastically supported by an elastic spring ( 141 ) in the cylinder ( 130 ), and said plunger ( 140 ) being compressible in a longitudinal direction of the cylinder ( 130 ) according to variation in pressure of the outlet pipe ( 120 ) to supply oil in proportion to the engine RPM, wherein in a low speed range (A) and a medium/high speed range (C), said oil pump is configured in a way such that the first pipe line ( 143 a ) and second pipe line ( 143 b ) of the plunger ( 140 ) are closed by the cylinder ( 130 ), wherein in a medium speed range (B), the oil pump is configured in a way such that the first pipe line ( 143 a ) connects the first input pipe ( 133 a ) to the first output pipe ( 134 a ) to partially return a hydraulic pressure of the outlet pipe ( 120 ) to the inlet side ( 110 ), and wherein in a high speed range (D), the oil pump is configured in a way such that the second pipe line ( 143 b ) connects the second input pipe ( 133 b ) to the second output pipe ( 134 b ) to partially return the hydraulic pressure of the outlet pipe ( 120 ) to the inlet side ( 110 ).