Method and apparatus for controlling fuel/air mixture in a lean burn engine

Patent · Tue Apr 07 00:00:00 EDT 1998

OSTI ID:871453

Kubesh, John Thomas ^[1]; Dodge, Lee Gene ^[1]; Podnar, Daniel James ^[1]

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1. San Antonio, TX

The system for controlling the fuel/air mixture supplied to a lean burn engine when operating on natural gas, gasoline, hydrogen, alcohol, propane, butane, diesel or any other fuel as desired. As specific humidity of air supplied to the lean burn engine increases, the oxygen concentration of exhaust gas discharged by the engine for a given equivalence ratio will decrease. Closed loop fuel control systems typically attempt to maintain a constant exhaust gas oxygen concentration. Therefore, the decrease in the exhaust gas oxygen concentration resulting from increased specific humidity will often be improperly attributed to an excessive supply of fuel and the control system will incorrectly reduce the amount of fuel supplied to the engine. Also, the minimum fuel/air equivalence ratio for a lean burn engine to avoid misfiring will increase as specific humidity increases. A relative humidity sensor to allow the control system to provide a more enriched fuel/air mixture at high specific humidity levels. The level of specific humidity may be used to compensate an output signal from a universal exhaust gas oxygen sensor for changing oxygen concentrations at a desired equivalence ratio due to variation in specific humidity specific humidity. As a result, the control system will maintain the desired efficiency, low exhaust emissions and power level for the associated lean burn engine regardless of the specific humidity level of intake air supplied to the lean burn engine.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• DOE Contract Number: ZCR-5-13519-01
• Assignee: Southwest Research Institute (San Antonio, TX)
• Patent Number(s): US 5735245
• Application Number: 08/735,105
• OSTI ID: 871453
• Country of Publication: United States
• Language: English

Related Subjects

method
apparatus
controlling
fuel
air
mixture
lean
burn
engine
supplied
operating
natural
gas
gasoline
hydrogen
alcohol
propane
butane
diesel
desired
specific
humidity
increases
oxygen
concentration
exhaust
discharged
equivalence
ratio
decrease
closed
loop
control
systems
typically
attempt
maintain
constant
resulting
increased
improperly
attributed
excessive
supply
incorrectly
reduce
amount
minimum
avoid
misfiring
increase
relative
sensor
allow
provide
enriched
levels
level
compensate
output
signal
universal
changing
concentrations
due
variation
result
efficiency
emissions
power
associated
regardless
intake
burn engine
lean burn
oxygen concentrations
air supplied
oxygen sensor
control systems
relative humidity
oxygen concentration
equivalence ratio
closed loop
natural gas
power level
output signal
exhaust gas
air mixture
gas discharge
fuel control
intake air
gas discharged
humidity sensor
exhaust emissions
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