System and method for reducing fuel consumption in a vehicle

1. A drive system for a vehicle, comprising:

an engine;

an alternator coupled to the engine, the alternator being configured to power at least one auxiliary load;

a traction motor system operatively coupled to drive wheels of the vehicle, the traction motor system being configured for receiving primary electrical power from the alternator and for propelling the vehicle in response to the primary electrical power; and

a motor electrically connected to the traction motor system and mechanically coupled to the engine through a variable torque coupling, the motor being configured to receive electrical power from the traction motor system in a dynamic braking mode of operation of the traction motor system and to communicate power to the engine during the dynamic braking mode.

2. The drive system of claim 1 , wherein:

the at least one auxiliary load includes at least one of a hydraulic pump or a control and motor cooling fan.

3. The drive system of claim 1 , wherein:

the motor is a DC motor.

4. The drive system of claim 3 , wherein:

the motor is mechanically coupled to the engine through a direct mechanical coupling.

5. The drive system of claim 1 wherein:

the variable torque coupling includes at least one of a belt, a chain, a gear, or a hydraulic coupling.

6. The drive system of claim 1 , wherein:

the motor is an AC motor; and

wherein the system further includes an inverter intermediate the traction motor system for converting DC electrical power from the traction motor system into AC electrical power for use by the AC motor.

7. The drive system of claim 6 , further comprising:

a clutch assembly connected to the AC motor and the engine, the clutch assembly being configured to selectively alter the magnitude of torque provided to the engine.

8. The drive system of claim 6 , further comprising:

at least one blower motor electrically coupled to the traction drive system; and

at least one blower mechanically coupled to the blower motor;

wherein the blower motor is configured to receive electrical power from the traction motor system in the dynamic braking mode of operation of the traction motor system and to drive the blower to provide cooling for the traction motor system.

9. The drive system of claim 8 , wherein:

the at least one blower motor is a pair of blower motors; and

the at least one blower is a pair of blowers.

10. The drive system of claim 8 , wherein:

the blower motor is electrically coupled to the traction motor system over an H-bridge.

11. The drive system of claim 8 , further comprising:

a battery electrically connected to the traction motor system and to the alternator;

wherein the battery is configured to receive electrical power from the traction motor system in the dynamic braking mode of operation of the traction motor system to recharge the battery and to supply stored electrical power to the alternator to crank the engine.

12. The drive system of claim 11 , further comprising:

a chopper intermediate the battery and the alternator, the chopper being configured for field excitation of the alternator during engine cranking.

13. The drive system of claim 1 , wherein:

the vehicle is an off-highway vehicle.

14. A method, comprising the steps of:

generating primary electrical power at an alternator connected to an engine;

operating a traction motor coupled in driving relationship to a wheel of a vehicle to propel the vehicle during a propel mode of operation and to generate electricity during a dynamic braking mode of operation, wherein in the propel mode of operation the primary electrical power is transmitted to the traction motor to power the motor;

utilizing the electricity generated during the dynamic braking mode of operation to power a motor configured to communicate power to the engine to offset an auxiliary engine load to decrease fuel consumption of the vehicle; and

controlling at least one of a speed and a torque of the motor in dependence upon a desired degree of offset for the auxiliary engine load.

15. The method according to claim 14 , wherein:

the motor is a DC motor; and

the motor is mechanically coupled to the engine through a variable torque coupling.

16. The method according to claim 14 , wherein:

the motor is an AC motor; and

wherein the method further includes the step of converting the electricity generated during the dynamic braking mode of operation into AC electrical power for use by the AC motor.

17. The method according to claim 16 , further comprising the step of:

operating a clutch assembly connected to the AC motor and the engine to alter the magnitude of torque provided to the engine.

18. The method of according to claim 17 , further comprising the step of:

utilizing the electricity generated during the dynamic braking mode of operation to power a blower motor connected to a blower, the blower being configured to provide cooling for the traction motor.

19. The method according to claim 17 , further comprising the step of:

utilizing the electricity generated during the dynamic braking mode of operation to recharge a battery of the vehicle.

20. The method according to claim 19 , wherein:

the battery is electrically connected to the alternator; and

the method further includes the step of supplying stored electrical power from the battery to the alternator to crank the engine during starting.

21. The method according to claim 14 , further comprising the step of:

at an inverter/rectifier, receiving the electricity generated during the dynamic braking mode of operation, and supplying the electricity to the alternator to produce a torque at the alternator.

22. The method according to claim 4 , wherein:

the auxiliary engine load includes at least one of a hydraulic pump or a control and motor cooling fan.