Unique Valve on New Honda Engines Could Help Advanced Powertrains Meet Emission Standards; Siemens EEGR Valve Cuts NOx Levels On New Accord 'Green' Engines
4 February 1998
Unique Valve on New Honda Engines Could Help Advanced Powertrains Meet Emission Standards; Siemens EEGR Valve Cuts NOx Levels On New Accord 'Green' Engines
AUBURN HILLS, Mich., Feb. 4 -- A technology helping Honda
meet California's Ultra Low Emission Vehicle (ULEV) standards two years ahead
of schedule could be a major factor in the industry's efforts to develop lower
NOx (Oxides of Nitrogen) producing, more fuel efficient powertrains of the
future.
The technology is a unique electrically actuated EGR valve from Siemens
Automotive that reduces emissions system cost and complexity.
The Siemens Electric Exhaust Gas Re-circulation (EEGR) valve is among
the technologies used by Honda in the 1998 Accord engines, the cleanest mass-
produced gasoline engines in North America.
The 1998 Accord is the first car to be sold in all 50 states to meet
California's stringent Low Emission Vehicle (LEV) standard, and one model will
be the first production automobile certified as an "Ultra-Low Emission
Vehicle" (ULEV).
These vehicles meet the LEV and ULEV standard for NOx based on state-of-
the-art engine and emissions technology which includes the Siemens valve,
according to Peter Hoffer, director of business and technology development for
the Emissions Components group of Siemens Automotive's Powertrain Division.
For the future, meeting NOx emission standards poses the biggest challenge
to GDI (Gasoline Direct Injection) and DI (Direct Injection for Diesel) engine
technologies. GDI and DI are advanced powertrain technologies considered by
many experts to be the alternative engines best able to meet global emission
and fuel consumption standards expected to take effect during the next decade.
"The Siemens valve offers GDI and DI diesel two important advantages,"
said Hoffer. "First, like conventional EGR systems, it lowers NOx by reducing
peak combustion temperatures. This is accomplished by diluting the intake air
with exhaust gas by recirculating a portion of the exhaust gas flow via the
EGR valve.
"But traditional EGR valves are actuated by manifold vacuum which will not
be available during unthrottled operation of GDI and DI diesel concepts.
"The more stringent LEV, ULEV and Federal Tier II standards require faster
valve response times and greater control accuracy than the vacuum actuated
valves can achieve," said Hoffer.
The EEGR valve provides these capabilities, he explained. "It's
essentially a very precise flow control valve using linear solenoid technology
for infinitely variable control of valve position. The accuracy is further
enhanced by an EEGR valve position feedback sensor."
The EEGR system also costs less and significantly reduces the number of
system components, vehicle assembly operations and complexity. These savings
result from the elimination or consolidation of a number of parts and
components: the back pressure transducer or vacuum control valve, plus tubes,
brackets and hoses.
"Another benefit of the EEGR valve can be improved fuel economy when
applied on engines designed specifically to tolerate high EGR rates," said
Hoffer.
The Siemens EEGR valve debuted in California on the 1996 Honda Civic HX,
which featured a 1.6-liter 4-cylinder engine with a variable valve timing
system (VTEC). That vehicle was the first to meet the California LEV
standard, which included NOx emission levels twice as strict as federal
requirements.
The ULEV-certified Accord, equipped with a new 2.3-liter, 4-cylinder VTEC
engine, will be sold in California and certain Northeast states beginning this
fall. It meets the strict California ULEV standard two years ahead of the
deadline for offering such engines.
ULEV requires achieving 0.04 grams per mile of non-methane organic
compounds (NMOG) -- unburned hydrocarbons (HC) produced during engine warm-up
-- which is 46 percent lower than the LEV standard for NMOG (0.075) and 84
percent lower than the current federal standard (0.25). The NOx standard is
0.2, the same as the LEV requirement.
Emission Standards
grams/mile
NMOG CO NOx
(carbon monoxide)
Federal Tier I 0.25 3.4 0.4
(current)
LEV 0.125 3.4 0.2
ULEV 0.04 1.7 0.2
Federal Tier II 0.125 1.7 0.2
SOURCE Siemens Automotive Corporation
