Back-Pressure and Fuel Type Effects on Exhaust Gas Oxygen Sensor Readings for a Single Cylinder Spark Ignition Engine Running on Gasoline and Ethanol

Excess Air Ratio Management in a Diesel Engine with Exhaust Backpressure Compensation

“…It is worth emphasizing that reliable validation results for Model 1, covering the λ range from 1 to 1.2, were presented in Irimescu [ 17 ]. However, due to the diesel combustion regime restrictions, this region was beyond the scope of the present study.…”

“…The k factor for lean mixtures was experimentally determined as 47 kPa. Taking another model from [ 17 ] and performing some manipulations, it is possible to directly estimate the apparent value of λ, as expressed by Equation (5): where Δp = p exh − p 0 . The constant m was experimentally determined to be 6.25·10 −3 kPa −1 .…”

“…The Bosch (Robert Bosch GmbH, Stuttgart, Germany) R&D group reported significant differences between the readings of their sensors for gasoline and ethanol [ 4 ]. On the other hand, Irimescu [ 17 ] used the above fuels and observed only minor differences solely in highly lean or highly rich mixture conditions and elevated pressures. Finally, Grannell et al [ 18 ] explained the significant delta in the sensor readings for gasoline and ammonia (NH 3 ) combustion by attributing it to the oxidation of unburned NH 3 on the sensor surface.…”

“…The above partially conflicting reports may result from the employment of different sensor technologies or different thermodynamic conditions of measurements. On the hardware side, the sensors usually differ in the reference pumping current definition that is either adjusted to ambient air (e.g., LSU 4.2 sensor by Bosch) or selected arbitrarily (e.g., LSU 4.9 sensor by Bosch) [ 17 ]. As far as test conditions are concerned, the diffusion-based operating principle makes sensors very sensitive to the exhaust backpressure [ 17 ].…”

“…On the hardware side, the sensors usually differ in the reference pumping current definition that is either adjusted to ambient air (e.g., LSU 4.2 sensor by Bosch) or selected arbitrarily (e.g., LSU 4.9 sensor by Bosch) [ 17 ]. As far as test conditions are concerned, the diffusion-based operating principle makes sensors very sensitive to the exhaust backpressure [ 17 ]. While this is typically not an issue for λ measurement in conventional spark ignition or diesel engine applications, the cylinder-individual estimation methods usually rely on upstream sensor mounting that is subjected to significant pressure fluctuations.…”