Oil Pump

OIL PUMP

Outline
A variable capacity trochoid oil pump is used for improved discharge efficiency and reduced fuel consumption. The former involute gear oil pump discharged oil in proportion to engine speed. The variable capacity pump also outputs oil in proportion to engine speed but, when the engine reaches a certain rpm, the output of the pump is fixed at us maximum to minimize the drive torque losses caused by the pump.

Oil Pump:

Construction
An outer rotor, inner rotor, and oil pump flange are installed within the pump housing of the trochoid gear oil pump. The oil pump flange and oil pump shaft are coupled to the inner rotor. The other end of the oil pump shaft is coupled to the pump impeller side of the torque converter, and via the converter, to the engine. As a result, the oil pump flange, the inner rotor, and the outer rotor rotate unitedly with the engine. A spool and spring installed in the discharge section of the pump housing regulates the oil discharge.





Operation
1. When the speed of the engine is low the spool is as shown in Fig. A, and the amount of oil discharged increases in proportion to engine rpm.
2. When the engine rpm increases and the p-p' differential pressure becomes greater, the spool is pressed against the spring and compresses it as it moves to the right. When the spool is in the position shown in Fig. B, the oil is redirected through port A to port B and circulates back to the inlet side of the pump, with the result that the amount of oil discharged fixed.