The business case for electric hybrid cars is pretty weak because so many heavy batteries are required and replacing them when they wear out is expensive. Another approach to energy storage is compressed air. Ford is taking this idea and pursuing compressed air hybrids. Still yet another approach uses hydraulic fluid compression to store energy.
Chandler noted that, "This smaller, lighter version of Permo-Drive's Regenerative Drive System (RDS) offers significant fuel savings, reduced emissions and improves brake life to the trucking industry and major fleet operators, including the U.S. military."
A U.S. Army vehicle equipped with the Permo-Drive system recently underwent three weeks of intensive testing. Preliminary results show a 27 percent improvement in fuel economy, a 36 percent jump in rapid-acceleration or "dash" capability and a 60 percent improvement in deceleration when comparing hydraulic-system deceleration rates to engine-braking.
Dennis J. Wend, executive director of the U.S. Army National Automotive Center, recently noted that, "In our modeling and simulation work to date, parallel hybrid-hydraulic systems show the potential to provide significant fuel-economy savings for future generations of trucks."
The US Army has a greater incentive than private industry to boost fuel efficiency of its vehicles because of the logistical cost and enormous difficulty of delivering fuel to remote battlefields. Therefore it is not surprising that the Army would be testing this technology.
Chandler pointed out that the company's hybrid hydraulic system also has been tested on commercial vehicles in Australia, where it achieved fuel economy gains of 33 percent or more. Permo-Drive's system captures normally wasted energy generated during braking, then releases it back into the vehicle's driveline when additional power is needed.
RDS technology can be applied to new or existing trucks. Key design features include an innovative inline axial-piston pump/motor, high-pressure accumulator energy-storage devices that utilize special composite materials, ultra-light-weight metals and advanced hydraulic and electronic engineering. The Permo-Drive system integrates vehicle dynamics, hydraulics, mechanical engineering, accumulator technology, material science, computer telemetry and electronics.
Computer control advances combined with materials advances are probably both essential enabling technologies that are making designs based on this type of hybrid technology possible.
The Permo-Drive RDS storage system includes two hydraulic fluid "accumulators" -- a high-pressure tank (up to 5,000 PSI) and a low-pressure reservoir. As braking takes place, energy is captured with the flow of oil from the low-pressure tank to the high-pressure accumulator. A central processor later controls the release of the oil during acceleration to enhance overall fuel economy and reduce emissions.
Technologies that capture braking energy would useful as a way to decrease fuel usage even in vehicles powered by fuel cells or batteries.
|Share |||Randall Parker, 2003 March 02 11:25 PM Energy Transportation|