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Closed Loop Control of Lean Fuel-Air Ratios Using a Temperature Compensated Zirconia Oxygen Sensor
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Abstract
Several recent papers describe closed loop fuel-air ratio control systems designed to operate at stoichiometric conditions because of the high three-way catalyst conversion efficiencies which occur only in a narrow band around stoichiometric. This paper investigates closed loop control of fuel-air ratio using a temperature compensated zirconia sensor at other than stoichiometric conditions. If engines can be made to run at very lean(Φ≈0.6-0.7) equivalence ratios through greater attention to proper fuel-air mixing and vaporization, CO, HC, and NOx emissions are minimized simultaneously. Closed loop control in the lean region makes the system insensitive to parameter variations and allows the fuel-air ratio to be maintained closer to the lean limit than would be possible under conventional open loop conditions.
Assuming lean combustion and using the Nernst equation for the oxygen sensor, equations are derived relating equivalence ratio to the oxygen sensor output voltage and temperature. Equations are also derived and discussed which give the sensitivity of predicted equivalence ratio to measurement errors in voltage and temperature and to variations in humidity and exhaust pressure. A simplified calculation scheme, which involves a linearization in equivalence ratio and which might be used in an onboard computer, is presented and its accuracy is discussed.
The theoretical results are verified using experimental data obtained on a CFR engine and a system is described which predicts and controls fuel-air ratio closed loop in the lean region based on oxygen sensor and thermocouple output voltages.
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Hubbard, M., Bonilla, J., Randall, K., and Powell, J., "Closed Loop Control of Lean Fuel-Air Ratios Using a Temperature Compensated Zirconia Oxygen Sensor," SAE Technical Paper 760287, 1976, https://doi.org/10.4271/760287.Also In
References
- Cassidy J. F. Jr., “Electronic Closed Loop Controls for the Automobile” Paper 740014 SAE International Automotive Engineering Congress Detroit January 1974
- Rivard J. G. “Closed Loop Electronic Fuel Injection Control of the Internal Combustion Engine” Paper 730005 SAE International Automotive Engineering Congress Detroit January 1973
- Rachel T. L. Gunda R. “Electronic Fuel Injection Utilizing Feedback Techniques” Session 36, IEEE International Convention and Exposition New York March 1974
- Zechnall R. Baumann G. Eisele H. “Closed Loop Exhaust Emission Control System with Electronic Fuel Injection” Paper 730566 SAE National Automotive Engineering Meeting Detroit May 1973
- Hubbard M. Powell J. D. “Closed Loop Control of Internal Combustion Engine Exhaust Emissions” Department of Transportation Final Report, DOT-TST-75-62 February 1974
- Hubbard M. “Applications of Automatic Control to Internal Combustion Engines” Stanford University 1975
- Gorille I. Rittmannsberger N. Werner P. “Bosch Electronic Fuel Injection with Closed Loop Control” SAE Paper 750368
- Spilski R. A. Creps W. D. “Closed Loop Carburetor Emission Control System” SAE Paper 750371
- Wimmer D. B. Lee R. C. “An Evalution of the Performance and Emissions of a CFR Engine Equipped with a Prechamber” SAE paper 730474
- Schweitzer P. H. “Control of Exhaust Pollution Through a Mixture-Optimizer” SAE paper 720254
- Eddy D. S. “Physical Principles of the Zirconia Exhaust Gas Sensor” Paper 73CH0718-7VT-C-3 presented at the IEEE Vehicular Technology Conference Cleveland December 1973
- Fleming W. J. Howarth D. S. Eddy D. S. “Sensor for On-Vehicle Detection of Engine Exhaust Gas Composition” SAE paper 730575
- Dueker H. Friese K. H. Haeker W. D. “Ceramic Aspects of the Bosch Lambda-Sensor” SAE paper 750223
- Camp J. Rachel T. L. “Closed-Loop Electronic Fuel and Air Control of Internal Combustion Engines” SAE paper 750369