Heat engine and electric motor torque distribution strategy for a hybrid electric vehicle

A hybrid electric powertrain system, comprising:

• a transmission for driving a pair of wheels of a passenger vehicle;
• a heat engine coupled to said transmission;
• an electric motor/generator coupled to said transmission;
• an accelerator pedal including a position sensor for detecting a position of said accelerator pedal;
• a controller unit for generating control signals to said heat engine and said electric motor/generator, wherein an engine control signal is determined based upon a limited rate of torque rise and a detected accelerator position;
• and
• wherein a motor control signal is determined based upon a difference between a determined torque request and a determined engine torque request.

A method of controlling a hybrid electric powertrain system including a heat engine and an electric motor/generator each coupled to a transmission for driving a pair of wheels of a passenger vehicle, comprising the steps of:

• a. determining an amount of motor torque available;
• b. determining an amount of engine torque available;
• c. determining an amount of motor torque that can be used to assist the engine in driving the vehicle;
• d. determining an amount of engine torque required for battery charging;
• e. determining a total amount of driving torque available by adding said determined amount of motor torque available for driving and said determined amount of engine torque available;
• f. determining an amount of requested torque based upon a detected accelerator position and said determined total amount of driving torque available;
• g. calculating a total torque request by adding said determined amount of torque required for battery charging and said determined amount of requested torque;
• h. determining a limited total torque request based upon a limited rate of increase for the calculated total engine torque request and said detected accelerator position;
• and
• i. determining an altered torque request based upon said calculated total torque request, said determined limited total torque request and said detected accelerator position.

A method of controlling a hybrid electric powertrain system including a heat engine and an electric motor/generator each coupled to a transmission for driving a pair of wheels of a passenger vehicle, comprising the steps of:

• detecting a state of charge of a vehicle battery, an accelerator position, a value representative of a current transmission gear ratio, engine speed and motor speed;
• determining an amount of motor torque available, based upon a detected motor speed;
• determining an amount of engine torque available based upon a detected engine speed and a detected value representative of a current transmission gear ratio;
• determining an amount of motor torque that can be used to assist the engine in driving the vehicle based upon a detected battery state of charge, a detected accelerator position and a determined amount of motor torque available;
• determining an amount of engine torque required for battery charging and alternatively an amount of motor torque required for discharging stored energy from said battery based upon a detected battery state of charge, a determined amount of motor torque available and a detected accelerator position;
• determining a total amount of driving torque available by adding said determined amount of motor torque available for driving and said determined amount of engine torque available;
• determining an amount of requested torque based upon said detected accelerator position and said determined total amount of driving torque available;
• calculating a total amount of engine torque requested by adding a determined amount of torque required for battery charging and a determined amount of requested torque;
• determining a limited engine torque requested amount based upon a limited rate of increase for the calculated total amount of engine torque requested and said detected accelerator position;
• calculating a motor torque request amount by subtracting a determined limited engine torque requested amount from a determined amount of requested torque;
• determining a motor command based upon said calculated motor torque request amount and said determined amount of motor torque available;
• and
• determining an engine command based upon said determined amount of engine torque available and said determined limited engine torque request amount.