Hybrid vehicle powertrain cooling system

A hybrid vehicle system comprising:

• an internal combustion engine;
• a radiator;
• an electric machine;
• power electronics operable to provide power to the electric machine;
• a coolant flowpath in thermal communication with the internal combustion engine, the radiator, the electric machine, and the power electronics, wherein the electric machine and the power electronics are connected in parallel to one another in the coolant flowpath to each selectively receive coolant from the radiator, and the internal combustion engine and the radiator are connected in series in the coolant flowpath and in series to each of the electric machine and the power electronics, and further comprising an internal combustion engine bypass that is configured to bypass the coolant flow around the internal combustion engine and a valve operable to selectively direct coolant to the radiator through the internal combustion engine or through the internal combustion engine bypass;
• a mechanically driven coolant pump to pump coolant through the internal combustion engine, wherein the internal combustion engine bypass is further configured to bypass the mechanically driven coolant pump, and an electrically driven coolant pump operable to circulate coolant through the coolant flowpath through the internal combustion engine bypass and through the mechanically driven coolant pump and the internal combustion engine, wherein each of the mechanically driven coolant pump and the electrically driven coolant pump are connected in the flow path in series to one another and in series to each of the electric machine and the power electronics to each provide coolant flow through the internal combustion engine to the radiator and from the radiator to the electric machine and the power electronics;
• and
• a controller operable to control the electric machine and the power electronics to provide power to the electric machine;
• wherein the controller is operable to selectively increase the temperature of the internal combustion engine by controlling at least one of the electric machine and the power electronics to provide increased heat to the coolant in thermal communication with the internal combustion engine and by circulation of the coolant to the internal combustion engine with the at least one of the mechanically driven coolant pump and the electrically driven coolant pump.

A method comprising:

• operating an internal combustion engine;
• pumping coolant with an engine driven coolant pump up to a threshold coolant flow rate through a closed loop flowpath in thermal communication with the internal combustion engine, a radiator, an electric motor, power electronics, and an electrically driven coolant pump, wherein the internal combustion engine is connected in the flowpath in series with the radiator and each of the electric motor and the power electronics, and the electric motor and the power electronics are connected in the flowpath in parallel with one another and in series with the electrically driven coolant pump, the engine driven coolant pump, the internal combustion engine, and the radiator;
• determining an engine temperature condition;
• controlling operation of the electric motor or the power electronics to increase heat transfer to the coolant effective to heat the engine based upon the engine temperature condition;
• and
• pumping coolant through the engine, the radiator and each of the electric machine and the power electronics through the closed loop flowpath with the engine driven coolant pump in conjunction with electrically driven coolant pump providing an increased coolant flow to the engine driven coolant pump above the threshold coolant flow rate.