Hybrids for trucks?

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Amid pressure to produce vehicles that provide improved fuel economy and reduced emissions, manufacturers are looking more seriously at hybrid propulsion systems. In fact, hybrid-powered passenger cars, the Honda Insight and Toyota Prius, for example, are already being sold in the United States. They both use two power sources – an internal-combustion engine and an electric motor – that work in concert to propel vehicle efficiency to higher levels.

A relatively recent entry into the fray, the Hyperdrive gasoline-electric hybrid vehicle-drive system, developed by the Paice Corp., Silver Spring, Md., will use both a high-power electric motor and a small-displacement, internal combustion, gasoline engine to power future delivery vans and light trucks, as well as passenger cars, according to the company.

Depending on power required in different driving modes, a Hyperdrive vehicle will be driven by the gas engine alone (via an engaged clutch), by the electric motor alone or by both together. A computer decides on the mode and runs the system at its highest efficiency.

A battery pack captures the energy output of the gas engine, and the electric motor uses that energy to power the vehicle when the gas engine cannot be used efficiently, or when required power cannot be delivered by the gas engine alone.

The gas engine runs on regular gasoline, but it runs only part-time, always in its most efficient range. And it needs to have only one-third to one-half the power and displacement of gas engines powering conventional vehicles. “Fuel efficiency improvements of 50 to 220 percent are possible,” claims David Polletta, Paice vice president of engineering.

Moreover, in smaller Hyperdrive-powered vehicles, there will be no need for a transmission, he adds. It is replaced by a power amplifier that regulates the power applied to the drive wheels, while a charging motor replaces the alternator and starter.

In a large SUV, a small two-speed transmission can be added to meet the full range of trailer-towing requirements.

Here are Hyperdrive’s operating modes:

  • In stop-and-go driving, the electric motor powers the vehicle. The gas engine is turned on only to charge the batteries, and only when needed. The gas engine never runs at idle and is not affected by the vehicle’s stopping or starting.
  • In most highway cruising, the gas engine powers the vehicle directly, without the electric motor. When extra power is needed for passing, the electric motor kicks in. In other hybrids, says Polletta, when the gas engine is powering the vehicle, a portion of its power output is converted to electric energy, resulting in conversion losses.
  • During braking, the electric motor absorbs deceleration energy and provides power to recharge the batteries. These consist of a bank of specifically designed 12-volt lead-acid cells and 48-volt battery modules. To assure safety, the 48-volt modules have an internal self-disconnect, which activates automatically whenever the ignition is off, or in an accident situation.

What makes this system believable as a commercial-vehicle powertrain is that, except for the control computer, it uses existing technologies and materials – nothing new, exotic or expensive.

Add to that the fact that Paice’s management includes former executives of Ford and GM, and that a full-scale prototype has already been tested at Roush Industries, and the picture becomes even more credible.

The company is discussing production with OEMs right now and can’t say when Hyperdrive will be a commercial reality. But I’m willing to go out on the limb of a hybrid fruit tree and say three to five years.