Electric oil pump system and controls for hybrid electric vehicles

A hybrid electric vehicle powertrain comprising an engine and an electric vehicle traction motor defining in part separate power flow paths to vehicle traction wheels;

• an engine lubrication oil pump in fluid communication with a lubrication oil flow circuit for the engine;
• an electric oil pump drive motor drivably connected to the lubrication oil pump;
• a powertrain control module and a vehicle system controller in electrical communication with the pump drive motor, the vehicle system controller being configured to develop engine power commands to the powertrain control module in response to system operating input variables and driver power demand whereby the engine is turned off during vehicle operation using solely traction motor power and the engine is turned on during a demand for engine power;
• the powertrain control module being configured to start the pump drive motor during a transition from an engine-off state to an engine-on state whereby the lubrication oil circuit is pressurized prior to engine acceleration to its steady-state speed, the powertrain control module being configured also to command a modification of oil flow rate from the lubrication oil pump to the engine as a function of at least one engine operating variable, including engine speed, engine power demand and engine oil temperature;
• an engine lubrication oil filter in the lubrication oil flow circuit;
• a sensor for determining engine oil pressure sensor;
• and
• a lubrication oil pressure display visible to a driver in communication with the powertrain control module whereby the driver is alerted by a signal generated by the powertrain controller to a need to change the lubrication oil filter as lubricating oil pressure on a flow inlet side of the oil filter is increased to a value exceeding a calibrated threshold level.

A method for establishing lubrication oil pressure for an internal combustion engine in a hybrid electric vehicle powertrain having an electric traction motor in electrical communication with a traction battery for complementing engine driving power with electric traction motor power, an engine lubrication oil pump in an engine lubrication oil flow circuit and a lubrication oil pump drive motor;

• the method comprising the steps of:
• measuring driver demand for power;
• monitoring engine and vehicle operating variables including driver demand for power, engine speed, engine oil temperature and traction battery state-of-charge;
• turning off the engine to effect an electric traction motor only drive mode in an operating mode when vehicle operating variables do not require engine power;
• turning on the engine in an operating mode when vehicle operating variables require engine power;
• turning on the lubrication pump drive motor during a transition from an engine-off operating mode to an engine-on operating mode whereby engine lubrication oil pressure is increased at the outset of engine cranking during an engine start;
• and
• controlling engine oil flow in the lubrication oil flow circuit throughout a range of engine speeds whereby lubrication oil flow requirements are satisfied by precisely metering oil flow without excess oil flow being developed at high engine speeds.