THE CUTTING EDGE: COMPUTING / TECHNOLOGY / INNOVATION : Engines That Could (Burn More Cleanly) : Autos: Two Southland companies say their computer-controlled design cuts emissions and improves efficiency.

For all the electronic bells and whistles that adorn a modern automobile, the basic mechanics of the internal combustion engine have been virtually untouched by the information technology revolution.

But two tiny Southland companies, Aura Systems of El Segundo and Digi-Valve of Santa Ana, hope to change all that--and help solve the smog problem too. They’ve developed a radical new design for car and truck engines that substitutes computer-controlled actuators for cam systems, an innovation that could decrease emissions by 25% and allow for vehicles that can run on both gasoline and cleaner-burning natural gas.

“This is the most remarkable thing since the engine was invented,” boasted Lance Nist, co-director of Digi-Valve. “We’re trying to introduce this technology on a broad spectrum. It’s probably the only way that will allow the emissions standards for 1998 and 2000 to be met.”

With actuators--tiny devices like computer chips that transform electronic signals, such as those from a car’s computer, into mechanical movements--the opening and closing of the valves on a piston engine can be controlled with great precision. That means the timing can be adjusted according to speed, and the engine can therefore burn fuel with maximum efficiency whether the car is going slow or fast.

“People have had these ideas for a while, but they didn’t physically have the ability to act on them,” said Bill Van Amburg, a spokesman for Calstart, a Burbank-based consortium of more than 100 small transportation component companies and university research groups. “With advanced microprocessors, we can make [engines] efficient to operate so they don’t require more electricity to power than is required to lift a camshaft.”

Aura Systems and Digi-Valve executives say major automobile manufacturers could be selling cars with actuator-controlled engines in the 1998 or 1999 model year.

Automobile engines are powered by pistons, which pump up and down inside their cylinders and transfer energy to the crankshaft, which turns the wheels of the vehicle. Fuel enters the cylinder through the intake valve and exits after it is burned through the exhaust valve.

Most cars’ engines are designed to work most efficiently at a cruising speed of 45 to 55 m.p.h., with the optimum speed depending on the car. (This is why gas mileage is better in freeway conditions than on city streets.) When the vehicle is going faster or slower than the optimum speed, the engine is wasting fuel, and that means more polluting exhaust goes out the tailpipe, said Ron Goldstein, Aura Systems’ senior vice president in charge of research and development.

In traditional engines, the intake and exhaust valves are pushed open by protrusions, or lobes, on the camshaft, which is essentially a metal bar. The valves close as the camshaft rotates and the cam lobes turn away from the valves. The cam moves faster or slower according to the speed of the car, but the angular distance between the lobes is fixed. That prevents the engine from fully adapting to suit driving conditions: Sometimes the exhaust valve opens before the fuel is fully burned, for example.

Actuators, on the other hand, can be controlled directly by the car’s computer. They can open and shut the intake and exhaust valves whenever the computer calculates that the fuel has been fully burned. That “infinitely variable timing” means the fuel is totally used up at any speed, creating greater fuel efficiency and less exhaust. It also means the same engine can run on either gasoline or natural gas because the valve timing can be varied for the slower-burning, higher-octane natural gas.

“What you want to optimize is energy per fuel,” Goldstein said. “If you can control the amount of time for combusting the fuel, then you can control how well you get energy out of the fuel.”

In the Aura and Digi-Valve engines, actuators replace the entire cam system--the camshaft, the timing belt, rocker arms and push rods, plus dozens of springs and valve lifters. That simplified design also makes the engine easier to build and repair, Goldstein said.

“You end up with a simple device that performs better but costs less to manufacture,” he said.

Aura Systems adapted its actuator--called the Electromagnetic Valve Actuator, or EVA--from flight simulator systems it developed for the Defense Department. EVA consists of a metal disk suspended between a pair of electromagnets and held in place by two springs. A pulse from the car’s computer turns one of the magnets on, drawing the disk toward it. As it moves, the disk compresses one of the springs and also drags along the valve stem, opening an entrance to an engine cylinder.

To close the valve, the computer shuts off the electromagnet, allowing the disk to fall away. The force of the once-compressed spring pushes the disk to the opposite electromagnet, and it pulls the valve into the closed position. At idle, the EVA engine uses just a tenth of the power of a traditional engine, and even at higher revolutions it uses only a quarter of the power.

Digi-Valve’s engine employs a somewhat different kind of actuator called an electrohydraulic valve actuator. It features a three-way digital control device that opens in response to a pulse from the car’s computer and allows high-pressure motor oil--the same stuff used to lubricate the rest of the engine--to fill a cavity and apply pressure on a valve, forcing it open.

To close, the computer switches the position of the three-way device, opening a pair of channels through which the oil escapes. Once the oil is gone, there is nothing to hold the valve down, so it rises into the closed position. The cycle lasts about 3 milliseconds.

Nist is still putting the final touches on the Digi-Valve engine. Although the system works for speeds of up to 12,000 r.p.m.--more than sufficient for most cars--Nist, who also builds race car engines, wants to design it to work at 25,000 r.p.m.

Working with Digi-Valve, Aura Systems completed its engine design in November and has inked eight contracts with companies and research groups eager to test EVA’s engine performance.

“This is a dream for engine development,” said I.J. Chung of Daewoo Heavy Industries in Inchon, South Korea, which will test the EVA engine for use in small trucks and vans. “It will be very helpful for engine performance optimization.”