Engine with belt/alternator/supercharger system

A belt, alternator, supercharger power system for an internal combustion vehicle engine, the system comprising:

• a positive displacement supercharger mounted to the engine for providing pressurized charge air to the engine;
• a belt drive connecting an output of the engine with an input of the supercharger for driving the supercharger, the belt drive including an overrunning clutch allowing the supercharger to overrun the belt drive;
• and
• an electric motor connected with the supercharger input for driving the supercharger at overrun speeds exceeding the belt drive speed.

A method of operating an internal combustion engine for use in a vehicle, the engine including a belt, alternator, supercharger system having a belt drive between the engine and the supercharger, a motor generator drive for independently driving the supercharger with battery power, an overrunning clutch allowing the motor to drive the supercharger at speeds exceeding belt speed, and inertia of the supercharger and associated components to drive the motor generator at low engine speeds or during supercharger deceleration, the method comprising at least one of the following four operating modes:

• (1) at low engine speeds, driving the supercharger with the motor generator to increase charge air pressure for increased engine torque;
• (2) at high engine speeds, supplementing the belt drive with power from the motor generator, thereby offsetting parasitic losses of the supercharger and increasing the resultant engine torque;
• (3) during deceleration of the vehicle with engine power reduced, driving the motor generator with the inertia of the overrunning supercharger rotors and the motor generator itself to temporarily provide electric energy to charge the battery, and
• (4) during transmission gear downshifts of the vehicle causing increased engine speed, applying momentary motor generator power to assist supercharger acceleration and reduce slipping of the belt drive to eliminate undesired “chirping” sounds.