Real-Time Calculation of EGR Rate and Intake Charge Oxygen Concentration for Misfire Detection in Diesel Engines Politecnico di Torino

Format:

Conference/Event

Author/Creator:

Catania, Catania, author.

Contributor:

Finesso, Roberto

Spessa, Ezio

Conference Name:

10th International Conference on Engines & Vehicles (2011-09-11 : Naples, Italy)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2011

Summary:

A new procedure for the real-time estimation of the EGR rate andcharge oxygen concentration has been developed, assessed andapplied to a low-compression ratio GMPT-E EURO V diesel engine.High EGR rates are usually employed in modern diesel engines toreduce combustion temperatures and NOx emissions,especially at medium-low load and speed conditions. The EGR rate isusually calibrated in steady-state conditions, but, under transientconditions, it can be responsible for misfire occurrence or nonoptimal combustion cycles, if not properly controlled. In otherwords, combustion instabilities can occur, especially during tip-inmaneuvers, which imply transition from high EGR (low load) to lowEGR (high load) rates. Misfire is determined by a temporaryreduction in the intake charge oxygen concentration during theclosure of the EGR valve.Therefore, a model-based approach for real-time estimation ofthe EGR rate and intake charge oxygen concentration is a powerfultool that could allow the engine ECU to prevent misfireoccurrence.In this paper, a semi-empirical correlation has been developedto estimate the EGR rate under steady-state and transient operatingconditions, on the basis of the measured pressure in the intakemanifold, of the measured pressure and temperature upstream fromthe EGR valve, and of the duty cycle signal of the EGR valve. Theintake charge oxygen concentration has been estimated on the basisof the measurements of the air mass-flow rate and injected fuelmass.The proposed technique has been applied to a modern EURO Vdiesel engine, in order to analyze two different engine transients:a severe tip-in maneuver with misfire occurrence and anacceleration ramp during the ECE cycle. The methodology has provedto be effective in the real-time monitoring of the EGR rate andintake charge oxygen concentration and to be simple enough to beimplemented in the engine ECU in order to diagnose misfireoccurrence in advance

Notes:

Vendor supplied data

Publisher Number:

2011-24-0149

Access Restriction:

Restricted for use by site license