Availability of total electrification option for components used with Allison H 40/50 EP hybrid system

7 November 2014

Allison Transmission Holdings Inc. announced availability of a new option to fully electrify components used with its H 40/50 EP hybrid propulsion system for transit buses and coaches. Co-developed with Vanner Inc., Increased Accessory Power II (IAP II) is a customizable electric distribution platform that provides power from the hybrid system to accessory components such as electric air conditioning, electric air compressors and power steering systems. (Earlier post.)

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IAP II includes either a Single or Dual Hybrid Beltless Alternator (HBA).

Allison’s standard H 40/50 EP system typically improves fuel economy up to 25 percent over standard diesel buses. When using a Vanner HBA with our system, a number of transit agencies in the US have reported an additional average fuel economy improvement of 16%, for a total improvement up to 41% or more.

In addition to improving fuel economy, IAP II has also demonstrated these benefits:

• Allows accessories to operate at the most efficient speeds, improving energy management by reducing parasitic loads.

• Increases brake responsiveness by building air brake pressure faster than a conventional engine-driven pump.

• Improves low-speed vehicle maneuverability due to smoother power steering.

• Enables faster cabin cooling, without straining the engine or burning unnecessary fuel by running engines at high idle.

IAP II builds on the foundation of Allison’s parallel hybrid propulsion system, as well as its release with the Vanner HBA and IAP I. Like IAP I, IAP II utilizes a high voltage distribution module (HVDM) for intelligent control of high voltage electrical power and an HBA (or dual HBAs) for DC to DC conversion of high voltage to 24 DC. However, IAP II adds an inverter that converts high voltage DC to high voltage AC that can power electric air conditioning, electric air compressor and power steering, while simultaneously eliminating the cost and need for the air conditioning system’s integral inverter.

The IAP II system is available in standard and articulated bus applications. All components will be delivered to OEMs on a pre-assembled and pre-wired rack. The racked solution enables customers to specify only those electrified components that they demand, while also offering better troubleshooting and easier maintenance than a boxed or individually sourced solution. Vanner will coordinate warranties for the IAP II ‘racked’ components.

Since 2003, Allison has delivered more than 6,500 hybrid propulsion systems which have accumulated nearly 650 million miles, saving more than 34 million gallons of fuel and preventing 340 metric tons of carbon dioxide from entering the atmosphere.