Diesel Hybrid Drive System

First ISE-developed diesel hybrid bus following delivery to New Jersey Transit.

The diesel hybrid system developed by ISE has several critically important features that are not offered in most competing diesel hybrid drive systems, including:

• Use of a smaller diesel engine (Cummins ISB02 5.9 liter engine), which helps to reduce fuel consumption, emissions, and noise.
• Electrically-driven power steering, braking, and air conditioning accessories, which are more efficient than the engine-driven accessories used in conventional vehicles and competing hybrid drive systems, and which allow the engine to be stopped without loss of accessory functionality.
• Advanced control system featuring an automatic engine start/stop algorithm, which shuts off the engine every time the vehicle stops. This results in further improvements in fuel economy and emissions.
• A choice between ultracapacitors, which are more efficient than competing battery-based energy storage subsystems, and advanced nickel sodium chloride Zebra batteries, which carry more energy per unit weight than the batteries used in competing hybrid drive systems.

These distinctions are of course in addition to use of the Siemens ELFA motors, controllers, and generators, which are more proven than the analogous components used in any competing hybrid drive systems.

Through mid-2004, the three buses at NJT buses accumulated nearly 50,000 miles of testing and operation, more than 40,000 of which was in revenue service with NJT. These are the only transit buses in the U.S. approaching or exceeding 6 miles per gallon, and have averaged a 25% fuel economy improvement over the most fuel-efficient conventional buses in the NJT fleet. In fact, on a cross-country trip from San Diego to New Jersey in May 2004, the third bus in this series averaged more than 8 miles per gallon. All three buses have performed with levels of reliability comparable to or better than conventional buses. At least four major bus manufacturers are now offering the ISE diesel hybrid system to their customers, and ISE expects to receive its first volume orders for diesel hybrid drive systems by 2005.

Beside is an illustration of a typical installation of the ISE diesel hybrid drive system. The Cummins engine shown is just one of several diesel engine options, including engines offered by Caterpillar. The ZEBRA battery energy storage option is also just one of numerous energy storage alternatives.