Hybrid improvement

BAE Systems has unveiled an improved model of its hybrid propulsion system at the American Public Transportation Association’s Annual Meeting and Exposition in San Diego.

The company’s latest HybriDrive system is based on its series diesel-electric hybrid technology. The new model is said to have simpler mechanics, reduced maintenance costs and the capacity to perform on multiple bus platforms.

The system can be adapted to various bus models by arranging the diesel engine and generator either inline or transversely. In addition, it has the capacity to generate up to 27kW of power for electrically operated systems such as air conditioning and power steering.

By combining the starter and generator to remove starter motor and flywheel, the system is simpler and lighter. Buses equipped with the new model will use a lithium-ion energy storage system to increase battery life and further reduce vehicle weight.

The absence of a mechanical transmission in the new design, traditionally a major maintenance item, has reduced costs and improved reliability.

The new configuration consists of an electric motor, a generator and computerised energy storage systems.

The diesel engine is independent of the electric drive motor, providing consistent speed. BAE Systems offers an optional accessory power system that is said to further improve efficiency and maintenance costs by eliminating alternators.

Hybridrive technology is already in use by transit agencies across North America with more than 1,500 buses powered by the system. These buses have recorded over 70 million miles of revenue services, saved almost five million gallons of diesel fuel and prevented more than 50,000 tons of carbon emissions.