Hybrid propulsion system for road vehicles

A hybrid propulsion system for use in vehicle operations, said propulsion system comprising:

• (a) a power splitting mechanical transmission for coupling to a tailshaft of the vehicle, wherein the power splitting mechanical transmission includes an epicyclic gearbox;
• (b) a first drive unit arranged for regenerative operation and coupled to the power splitting mechanical transmission;
• (c) a second drive unit arranged for regenerative operation and coupled, independently of said first drive unit, to the power splitting mechanical transmission;
• (d) a non-regenerative third drive unit coupled, in parallel to said power splitting mechanical transmission, to the tailshaft;
• and
• (e) propulsion control means for coordinating operation of the drive units in accordance with a plurality of predetermined modes corresponding to a driving cycle of said vehicle;
• wherein each of the first, second and third drive units includes a different type of energy storage means and said propulsion system further including:
• (A) a ring gear of the epicyclic gearbox arranged for coupling to the tailshaft;
• (B) the first drive unit being coupled to a sun gear of the epicyclic gearbox;
• (C) the second drive unit being coupled to a planetary gear carrier assembly of the epicyclic gearbox;
• and
• (D) the third drive unit being coupled to the tailshaft via a speed changing transmission;
• whereby the epicyclic gearbox delivers torque to the tailshaft for propelling the vehicle or receives torque from the tailshaft for retarding the vehicle.

A hybrid propulsion system for use in vehicle operations, said propulsion system comprising:

• (a) a power splitting mechanical transmission for coupling to a tailshaft of the vehicle, wherein the power splitting mechanical transmission includes an epicyclic gearbox;
• (b) a first drive unit arranged for regenerative operation and coupled to the power splitting mechanical transmission;
• (c) a second drive unit arranged for regenerative operation and coupled, independently of said first drive unit, to the power splitting mechanical transmission;
• (d) a non-regenerative third drive unit coupled, in parallel to said power splitting mechanical transmission, to the tailshaft;
• and
• (e) propulsion control means for coordinating operation of the drive units in accordance with a plurality of predetermined modes corresponding to a driving cycle of said vehicle;
• wherein each of the first, second and third drive units includes a different type of energy storage means and said propulsion system further includes:
• (A) a planetary gear carrier assembly of the epicyclic gearbox being arranged for coupling to the tailshaft;
• (B) the first drive unit being coupled to a ring gear of the epicyclic gearbox;
• (C) the second drive unit being coupled to a sun gear of the epicyclic gearbox;
• and
• (D) the third drive unit being coupled to the tailshaft via a speed changing transmission;
• whereby the epicyclic gearbox delivers torque to the tailshaft for propelling the vehicle or receives torque from the tailshaft for retarding the vehicle.

A method for controlling a hybrid propulsion system for a vehicle, which propulsion system includes at least two drive units arranged for regenerative operation and coupled to a power splitting mechanical transmission independently of each other, which mechanical transmission is coupled, in parallel with a non-regenerative third drive unit, to a final drive of the vehicle and wherein each of the first, second and third drive units includes a different type of energy storage means, said method including the steps of:

• determining current state of the propulsion system by monitoring status of each drive unit, including respective operating speeds and energy storage levels;
• receiving a demand signal indicative of desired vehicle motion;
• and
• if the demand signal indicates that negative wheel power for braking the vehicle is desired:
• operating any of the regenerative drive units regeneratively in accordance with current system state;
• or
• if the demand signal indicates that positive wheel power for cruise or acceleration is desired:
• operating one or more of the drive units propulsively in accordance with current system state;
• or
• if the demand signal indicates that no wheel power is desired, the vehicle being stationary:
• operating selected ones of the drive units for replenishing energy storage means associated with the regenerative drive units;
• which steps are repeatedly iterated in order to control the propulsion system with an optimum trajectory to a desired system state indicated by the demand signal.