Hybrid vehicles

In a method of controlling an internal combustion engine of a hybrid vehicle, said engine being operatively connected to drive wheels of said vehicle through a clutch, said vehicle further comprising a traction motor operatively connected to drive wheels of said vehicle, a starter/generator motor operatively connected to said engine for starting said engine and for providing electrical power in response to torque from said engine, a battery bank adapted to store electrical energy to power said traction motor and to start said engine, at least one inverter/charger adapted to cooperate with said traction motor and said starter/generator such that said traction motor can be operated to provide torque to said road wheels responsive to electrical power from said battery bank, or to provide electrical power to said battery bank responsive to torque from said road wheels, and such that said starter/generator can be operated to provide torque to start said engine, or to provide electrical power to said battery bank responsive to torque provided by said engine, and a microprocessor adapted to control operation of said engine, said traction motor, said starter/generator, and said at least one inverter/charger, so as to control flow of torque and electrical power therebetween in response to sensed parameters, the improvement comprising:

• establishing at least four vehicle operating modes, including:
• a mode I, wherein said engine is not operated and said vehicle is propelled by torque from said traction motor in response to electrical power drawn from said battery bank;
• a mode II, wherein said vehicle is propelled by torque from said traction motor in response to electrical power drawn from said battery bank, and said starter/generator is driven by torque provided by said engine to provide electrical power to recharge said battery bank;
• a mode IV, wherein said vehicle is propelled by torque from said engine;
• and
• a mode V, wherein said vehicle is propelled by torque from said engine and from said traction motor in response to electrical power drawn from said battery bank;
• wherein said microprocessor controls operation of said V engine, said traction motor, said starter/generator, and said at least one inverter/charger so as to operate said vehicle in a selected one of said operating modes in response to the instantaneous torque demands (RL) of said vehicle, and said selected operating mode being selected such that said engine is operated only in response to a load equal at least to a predetermined minimum value of its maximum torque output.