New Engine Technology Will Boost Fuel Mileage

One design engineer who really loves the new Obama Administration fuel mileage requirements is Tom Hollis, who has invented a new digital rotary control valve (DRCV) system that significantly boosts engine efficiencies.

Although many engine functions have become electronic in recent years, engine thermal management has stubbornly resisted.

"Since Cadillac first installed a thermostat in 1914, basically all automotive engines have utilized an ‘analog' thermostat to control the interaction of the engine with the radiator system," says Hollis. "This system, while always incorrect, was inexpensive and provided adequate engine function."

The U.S. Environmental Protection Agency (EPA) establishes the standard for engine thermal management. "There was no requirement for all those years other than the 23C EPA cold-start test," says Hollis. "Everything was focused on doing that."

At -40C the thermostat still opens up even though the engine is running cold. That happens because it's an analog circuit. It operates at +40C ambient and -40C ambient in exactly the same way. The key item to remember is "Every BTU that exits through the radiator provides zero heat energy value," says Hollis.

"A main objective of our approach is to completely temperature map the engine, centered on the combustion chamber, to determine actual known optimum engine operating temperatures under all driving conditions," says Hollis, a 25-year GM mechanical and electrical engineer who started a company called Electronic Engine Temperature Control Systems in Medford, NJ. Engine combustion surface temperatures are measured by placing thermocouples near the exhaust valve and the intake valve.

"The ideal operating temperature for engine oil for maximum lubrication value is between 110C and 120C," says Hollis. "We regulate the bypass coolant circuit around the engine up to a maximum 120C, to always provide a known optimum constant engine oil temperature – irrespective of either ambient temperatures or engine load conditions." 

A test of the DRCV system in Timmins, Ontario on a highly instrumented Jaguar showed that the system:

• Provides 8-percent fuel economy savings, based on winter driving in Ontario. This savings is based only on thermal management of engine oil. More savings are possible when transmission fluid temperatures are included in a total powertrain system approach.
• The DRCV system always maintains the engine oil temperature well above the dew point, thereby providing a thermal contamination barrier. Hollis envisions going from a present 7,500-mile interval on engine oil to possibly 30,000 miles.

The economics of the system appear favorable. Hollis says the DRCV costs under $60 installed. Analog thermostats used on cars cost only $15 to $20, but the difference in initial cost will be made up very quickly with savings on fuel and oil. Plus it's a quick way for auto OEMs to move closer to the new federal mileage standards.

But why has it taken so long?

Hollis began working on the concept in 1994 when he revisited information obtained from his involvement with "vapor phase cooling" systems in the early 1980s.

Anyone familiar with technology development in Detroit, MI knows there is a lot of inertia and a big "not-invented-here" syndrome. Hollis graciously says, "When you make a change there is always a warranty factor. Any time you make a technology change you don't know what's going to happen. It's tough to increase costs where the customer is not demanding it."

High gasoline costs, concerns about climate change and the new federal mileage standards are all game-changers however.

Hollis says we will see the DRCV on production cars soon. "It probably will come in through Europe because there are major programs on carbon dioxide reduction there." Two DRCV programs are expected to launch this year with two specialty European car makers, including Jaguar LandRover. Jaguar was close to an implementation six years ago, but Ford stopped the program because of financial issues not related to the DRCV.

One of the biggest obstacles for Hollis in the past dozen or so years was finding a funding partner. He hooked up last year with MileageMatrix Inc., a venture capital-based startup in Bellevue, WA that wants to become a leader in carbon dioxide reduction approaches.

The technology will get lots of attention at the National Plastics Exposition June 22-26 in Chicago. The DRCV will be on display in the International Plastics Design Showcase, which is co-sponsored by Design News. It will also be shown by technology partners Minco Tool and Mold (McCormick Place North Hall No, 60021) and DuPont Engineering Plastics (West Hall, No. 113011).

Hollis has had a relation with The Minco Group for more than 20 years going back to his days at General Motors.

Minco built prototype tooling last fall for three plastic parts, which required significant work on mold design. "The tolerances on the parts are tight, and gating required a lot of work," says Gary Deaton, manager of marketing and manufacturing at Minco, which is located in Dayton, OH.

The biggest challenge was the parts needed to be perfectly round. DuPont assisted in testing to make sure that cavities were filled precisely with glass-filled resins. Minco molded prototype parts on electric Mitsubishi machines 300 tons and down.

The materials used are DuPont Zytel HTN high-performance polyamide for the valve body, tube and diverter.  The materials provide resistance to continuous exposure to hot long-life coolant up to 130C, and retention of properties with moisture.

"We had to be very sensitive to expansion and contraction because all surfaces are always ‘wet' and we needed a ‘fluid bearing' to prevent sticking," says Hollis. "Zytel HTN PPA performed well in these conditions, allowing us to take advantage of the lightweight nature of plastics and overall cost advantage over metals."

New system components are designed to provide continuous "digital" temperature control for both the engine and transmission. These components will include the new DRCV, computer and heat exchangers. In the future, Hollis expects an electric water pump might also be included. Hollis says the system works well on internal combustion, hybrid and electric engines.

Not surprisingly, the DRCV from Hollis is not the only game in town. Companies such as Carl Fredenberg, Bosch, Ranco, Valeo, Bosch, Visteon, Ford, Dana, EMP and Gerate-und Pumpenbau have all discussed some variation of a technology to digitally manage engine temperatures. None has gained commercial traction.

Ranco, a unit of Invensys, is the world's largest supplier of automotive coolant control valves and is rumored to be working on the Chevy Volt program.

Hollis gets kudos for sticking with his idea. He also says he has a strong intellectual property position with 19 U.S. patents, many covering control technology. Patents have also been granted or are pending around the world. MileageMatrix now has an exclusive license for all the patent rights established by Hollis over the past 15 years.

He also feels his development has a technology edge. A unique grooved diverter outside diverter and valve body inside diameter provide an important "non-stick" feature, for example.