Parallel Drive for Trucks Follows Success with Buses
Allison Transmission unveiled its entry into the commercial hybrid truck and shuttle bus markets at the Work Truck Show. Essentially an add-on hybridization of its current fully-automatic 3000 series transmission, the new parallel drivetrain is aimed at medium- and heavy-duty trucks in distribution, refuse, utility and shuttle applications.
Production will begin later this year, and talks are under way with OEMs and potential customers, said Laurie Tuttle, Allison hybrid programs VP. Fuel savings are expected to be 25%, she said.
The fully-automatic parallel hybrid propulsion system is of the regenerative braking kinetic energy recovery type: it captures electricity as the vehicle brakes, stores it in batteries, and then uses it to assist propulsion or power other functions.
The main components are a motor-generator by Remy International (its high power-to-weight ratio HVH 4210 model), lithium ion prismatic cell batteries by Delphi Automotive Systems, and power controllers, inverters and DC-to-DC converters.
The battery packs are modular, allowing an operator to choose up to four packs per vehicle to match storage capacity with specific vehicle or duty cycle. “An operator doesn’t have to buy too much capacity,” Tuttle said.
‘All the Hybridization Is Outside’
All the hybridization is outside the Allison 3000 transmission, keeping down costs and complexity, she said. In the same vein, the electronic controllers and battery packs are scalable, with the former being designed for a family of hybrid transmissions with minimum development costs.
The controllers include automatic load-based shift sensing (the vehicle changes gear without dropping engine revs), and vehicle acceleration control will be offered as an option. Prognostics are also built in, helping to avoid unnecessary maintenance.
The motor-generator can provide peak torque of 571 lb-ft from 0-1,300 rpm, or peak power of 134 horsepower, limited by the inverter. It is cooled by Allison’s TranSynd cooling system, which lowers operating temperatures.
Nestled into the motor-generator is the engine-disconnect clutch. The packaging allows a power module just 11 inches long.
The Delphi batteries have an energy capacity of 1.6 kilowatt-hours per 50-kilowatt pack, and a typical 100-kilowatt system will use two 50-kilowatt packs.
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Source: Allison release, Fleets & Fuels at the Work Truck Show