Dual oil supply pump
An automotive engine oil pump assembly having first and second pump mechanisms contained within a common housing. A shaft rotatably supported in the housing drives the pump mechanisms in a conventional manner. The pump mechanisms are offset in phase to reduce flow pulsations through the housing and limit pump noise and vibration. The first pump mechanism communicates with a common inlet and first outlet of the housing. The second pump mechanism communicates with the common inlet and second outlet of the housing. A common reservoir connected to inlets of the first and second oil pump mechanisms provides a supplemental oil source to balance oil pressures at the pump inlets to prevent pump cavitation and further reduce pump noise and vibration.
1. An engine oil pump assembly comprising:
a housing defining an interior cavity and including a common inlet for receiving oil from an external reservoir, first and second outlets for supplying pressurized oil for lubrication of separate external mechanisms with return to the external reservoir, and a common internal reservoir disposed within the housing;
a shaft extending longitudinally though the housing and having an external drive;
a first pump mechanism driven by the shaft and communicating with the common inlet and the first outlet of the housing;
a second pump mechanism driven by the shaft and communicating with the common inlet and the second outlet of the housing;
a first pressure relief valve connected to receive oil from the first pump mechanism and to limit pressure to the first outlet by discharging excess oil flow to the common internal reservoir;
a second pressure relief valve connected to receive oil from the second pump mechanism and to limit pressure to the second outlet by discharging excess oil flow to the common internal reservoir; and
the common internal reservoir connected to supply supplemental inlet oil to the first and second pump mechanisms.
2. An oil pump assembly as in claim 1 wherein the first pump mechanism is advanced in relation to the second pump mechanism to reduce pulsation.
3. An oil pump assembly as in claim 1 wherein oil flow between the common inlet of the housing and the first pump mechanism is restricted.
4. An oil pump assembly as in claim 3 wherein the common internal reservoir supplies additional oil flow to the first pump mechanism.
5. An oil pump assembly as in claim 3 wherein the common internal reservoir supplies additional oil flow to the second pump mechanism.
6. An oil pump assembly as in claim 1 wherein the oil pump mechanisms are gerotors.
7. An oil pump assembly as in claim 1 wherein the first and second outlets each discharge oil to an independent oil circuit.
8. An oil pump assembly as in claim 7 wherein the first outlet supplies oil to an engine main bearing gallery.
9. An oil pump assembly as in claim 7 wherein the second outlet supplies oil to an engine cam gallery.
10. A method of operating a dual oil supply pump assembly, comprising the steps of:
providing an oil pump assembly including a housing defining an interior cavity and including a common inlet for receiving oil from an external reservoir, first and second outlets for supplying pressurized oil for lubrication of separate external mechanisms with return to the external reservoir, and a common internal reservoir disposed within the housing, a shaft extending longitudinally through the housing and having an external drive, a first pump mechanism driven by the shaft and communicating with the common inlet and the first outlet of the housing, a second pump mechanism driven by the shaft and communicating with the common inlet and the second outlet of the housing, a first pressure relief valve connected to receive oil from the first pump mechanism and to limit pressure to the first outlet by discharging excess oil flow to the common internal reservoir, a second pressure relief valve connected to receive oil from the second pump mechanism and to limit pressure to the second outlet by discharging excess oil flow to the common internal reservoir and the common internal reservoir connected to supply supplemental inlet oil to the first and second pump mechanisms;
rotating the shaft to operate the first and second pump mechanisms;
drawing oil through the common inlet with the first pump mechanism;
drawing oil through the common inlet with the second pump mechanism;
supplying pressurized oil to the first outlet and to the first pressure relief valve with the first pump mechanism, thereby allowing the first pressure relief valve to control oil pressure at the first outlet by discharging a portion of the oil to the common internal reservoir;
supplying pressurized oil to the second outlet and to the second pressure relief valve with the second pump mechanism, thereby allowing the second pressure relief valve to control oil pressure at the second outlet by discharging a portion of the oil to the common internal reservoir; and
supplying the pump mechanisms with supplemental inlet oil from the common internal reservoir.
11. A method as in claim 10 including reducing flow pulsations through the pump assembly by advancing the phase of the first pump mechanism in relation to that of the second pump mechanism.
12. A method as in claim 10 including providing increased flow from one of the pump mechanisms to supply additional oil to the common reservoir to provide additional supplemental inlet oil for the other pump mechanism.