Since the advent of exhaust gas recirculation valves in vehicle engines, automotive engineers have searched for a simple way to keep oil cleaner.

Now, engineers at Engineered Machine Products Inc. (http://rbi.ims.ca/3846-564) may have found a way. By developing a device known as the Advanced Filtration System, they've enabled end users to continuously filter engine oil and automatically replace dirty filter media, thus allowing oils and filters to last more than 100,000 miles.

Engineers Jason Cousineau, David Allen, and others who participated in the development of the filtration system say that it could dramatically reduce maintenance time for big, over-the-road trucks, which today must often submit to as many as ten, one-hour-long, oil filter replacements per year. Moreover, the company's engineers say the technology could also be applied to small passenger vehicles and industrial systems.

The filtration system, funded in part by the U.S. Department of Energy, consists of an electric oil-transfer pump, a self-indexing reel-to-reel filtering cartridge, and a housing to enclose it. The reel-to-reel cartridge enables the filtration system to automatically replace used or dirty filtering media, thus providing a continuous supply of clean filter material that never clogs.

The key to the new system is its use of a differential pressure sensor, digital signal processor (DSP), and a proprietary software algorithm that enables it to determine when it's time to move the reel forward. It accomplishes that by measuring the pressure difference between two cavities on the upstream and downstream sides of the filtering paper. The pressure difference increases when contaminants in the oil collect on the filter paper as they try to pass from the unit's inlet cavity to its outlet cavity. As these contaminants build up, oil pressure on the inlet side rises. Aided by passages from each cavity, the pressure sensor measures the pressure on both sides. Then, working with the DSP and built-in software algorithms, the system decides when it's time to change the filter paper.

"When the pressure difference reaches some pre-determined value, it means that section of the filter paper is plugged," says David Allen, vice president of product development for Engineered Machine Products. Recognizing the need for new paper, the oil pump stops, an inflatable seal on the device deflates, and the cartridge's take-up reel spins. The take-up reel pulls dirty paper out of the window, tugging clean paper from the supply reel into the window.

The company's engineers say that there's enough filter paper in the reel-to-reel system to last for 100,000 vehicle miles, even on most big diesel engines. "When all the paper from the supply reel is transferred to the take-up reel, you pull the cartridge out and pop in a new one," Allen says. "It's kind of like a typewriter ribbon or a printer cartridge."

Engineered Machine Products' engineers say that the technology is especially important in light of the required use of exhaust gas recirculation (EGR) valves, which recirculate exhaust gas to the combustion chamber to lower emissions, but in doing so deposit soot in oil. Because the new filter can sift out particles down to 2 microns in size, it catches a lot of the soot redeposited by the EGR valve. All this is done off-line-oil is drawn from the engine's oil sump and returned there after it's filtered. That way, filtering doesn't interfere with the operation of the engine's lubrication system.

Moreover, the filter could save money for over-the-road truck fleets, many of which are now searching for ways to extend their maintenance intervals.

Jason Cousineau holds a BSME from Michigan Technological University and has a patent pending on the device and a separate patent for electric oil pump technology he developed. David Allen has designed over 20 engine pumps, many employed in diesel engines.