Azure takes the middle ground with new hybrid electric shuttle bus

Diesel Progress North American Edition, Feb, 2006 by Bill Siuru

Hybrid electric vehicles are a hot ticket right now. Ford, GM, Toyota, Honda and others are selling all the hybrid cars they can build. At the other end of the scale, General Motors and DaimlerChrysler are delivering their EP System and HybriDrive-powered hybrid transit buses to many cities around the country. Mack, International, Dana and Eaton are developing hybrid systems for the medium to heavy commercial truck market.

Amid all that big-name competition, Canada-based Azure Dynamics Corp. is covering the ground between with its series and parallel hybrid products, which include shuttle buses, delivery trucks and taxis.

Recently, Azure launched its new hybrid electric CitiBus. This 20-passenger shuttle bus uses the same chassis and G1 hybrid electric drive system as featured on Azure's delivery van already in service with Purolator Courier Ltd. and the United States Postal Service. Purolator has ordered 115 of the hybrid electric vans and has options to purchase as many as 2000.

Five of the new hybrid-electric shuttle buses will be used in the Bronx Clean Commuter Van Program operated by the Bronx Overall Economic Development Corp. Another four have been purchased by the Brooklyn-based UPROSE for use by the Al Noor School, the Chinese-American Planning Council and Sunset Park Senior Center.

The CitiBus uses a 178 in. wheelbase chassis supplied by Workhorse Custom Chassis and Commercial Body Builders supplies the shuttle bus body. When fully loaded it has GVWR of 15,500 lb. The ADA-compliant bus can accommodate two wheelchairs.

In an Azure G1 series hybrid electric vehicle, a 115 hp (85 kW) Siemens ac induction electric motor drives the rear wheels. The motor, which has a peak output of 201 hp (150 kW), is powered from two sources--a sealed, maintenance-free Cobasy NiMH battery pack or an onboard Siemens permanent magnet generator. The generator is driven by a GM Vortec 4800, 4.8 L V8 gasoline engine.

The batteries are recharged by the generator and through regenerative braking. According to the company, series hybrids are best suited for stop-and-go drive cycle applications.

One advantage of a series hybrid for shuttle bus and delivery van applications is their ability to operate on electric power alone when at reduced speeds. The engine can also operate independent of the vehicle speed, thus allowing the engine rpm to be chosen for best fuel economy. In the hybrid mode, the range is 360 miles with a top speed of 65 mph.

Voltage is stepped down from the system voltage of 336 V to provide 12 V accessory power via a dc-dc converter.

Azure Dynamics has also developed a smaller G2 series hybrid system that was installed in three of the unique black London taxis to demonstrate its ability to meet upcoming mandates that require London taxicabs to meet Euro 3 emission standards. The G2 system features a 60 hp, four-cylinder, 1.4 L Ford Gemini Stage 4 diesel engine driving a generator that supplies electricity to an electric transaxle, which drives the rear wheels.

Excess energy is stored in a nickel chloride (NiCL) battery that can supply energy to the transaxle when additional power is needed. The permanent magnet generator produces 45 kW continuous power at 300 V. The electric transaxle's ac induction motor can supply a peak power output of 96 hp (67 kW) to the wheels. The vehicle can also operate in pure electric or zero-emission mode, drawing 100% of its power from the battery pack.

Azure has also developed the Super 7 series-parallel hybrid system for delivery trucks with GVW of 18,000 to over 30,000 lb. This truck is based on a Kenworth T300 Class 7 chassis powered by a 260 hp, six-cylinder Cummins ISB diesel engine with an Allison MD3060P automatic transmission. Electric energy is stored in maintenance-free Maxwell ultracapacitors. Two of these trucks will be delivered to the Charmer-Sunbelt Group for use in New York City's five boroughs and western Nassau County. During their operation the trucks will also be used to document the fuel savings and performance characteristics of hybrids compared to conventional trucks.