A method of lean air–fuel ratio control using combustion pressure measurement

Abstract

A method of lean air-fuel ratio control using combustion pressure measurement Lee, Albert T.; Wilcutts, Mark; Tunestål, Per; Hedrick, J. Karl General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractIn this paper a method for control of air-fuel ratio (AFR) in cold or lean-burning spark-ignited engines is investigated. The technique uses combustion pressure as measured by a cylinder-mounted sensor, and is based on the phenomenon of increasing cycleto-cycle combustion pressure variation as the air-fuel mixture approaches the limits of flammability. The cylinder pressure is measured from one engine cycle to the next, and large drops in mean effective pressure (IMEP) are used as an indicator of poor combustion. In response, the airflow or fuel flow to the engine can be manipulated. In a series of experiments, the air and fuel are alternately investigated as control inputs, and performance compared. The resulting control system is a high-bandwidth AFR control strategy that can be used under cold or lean conditions when conventional exhaust gas oxygen sensor cannot be used. Moreover, the method is directly tied to the combustion process and the relevant performance measure F combustion stability F that is perceptible to the driver as a rough-running engine. r

Online optimization of automotive engine coldstart hydrocarbon emissions control at idle conditions

“…In Tunestal et al, 29 the authors employed in-cylinder measurements to predict engine's AFR for automotive coldstart control applications. Also, the application of lean AFR control for HC emission reduction was investigated in Lee et al 30 In Giorgetti et al, 31 the application of hybrid automata for automotive engine control was discussed. Moreover, an early model-based controller software verification technique with coldstart HC emissions control as an example was proposed in Shahbakhti et al 32 In addition, the design and optimization of a hybrid switching controller for reducing the HC emissions of an automotive engine during the coldstart phase of FTP-75 drive cycle were introduced in Salehi et al 33 The minimization of tailpipe HC emission over the coldstart period for a given engine was formulated using the engine model and solved using the PMP algorithm by Azad et al 8 Then, a systematic method based on a sensitivity analysis of the objective function (the tailpipe HC emission) was proposed to reduce the complexity of the engine model components without loss of their control-relevant accuracy.…”

Ion Based High-Temperature Pressure Sensor

“…7 Saitzkoff et. al., investigated the use of the spark plug to measure pressure for internal combustion engines and derived a theoretical model that showed good correlation to actual pressures in high load engine conditions.…”

“…In recent years, the spark plug has been used as a diagnostic tool to measure the equivalence ratio, knock, misfire and is even used as a feedback sensor for ignition control. [7][8][9][10][11] These methods apply a constant DC voltage across the sparkplug causing it to act as a capacitor. When the spark is not occurring, the ionization can be measured as a current across the gap.…”

Automotive engine hybrid modelling and control for reduction of hydrocarbon emissions

“…Controllers with multiple control inputs have been developed, although exhaust gas temperature, ignition timing and air-fuel ratio (AFR) continue to be used the most. Lean-limit control to reduce the HC emissions is used in Lee et al (2001). A practical approach is followed in Chan and Hoang (1999): maintaining high idle speed with a high value of ignition retard (HVIR) with excess air factor; both together give high engine exhaust temperature (T exh ).…”