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
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 âanalog' thermostat to
control the interaction of the engine with the radiator system," says Hollis.
"This system, while always incorrect, was inexpensive and provided adequate
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 â 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 âwet' and we needed a âfluid 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
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.