Abstract
Keywords DOE, Modelling, Calibration, Optimisation, Emissions
Abstract Visteon reviewed the calibration processes required to calibrate its engine control unit (ECU) from the dynamometer calibration phase through to the vehicle calibration sign off and identified key areas where the use to advanced statistical models would help provide optimal ECU calibrations. This paper will provide an overview of the dynamometer based calibration methodologies and will reveal the route to optimal calibration generation. The steady state base engine mapping uses a combination of two DOE experiments in order to model the responses required for the steady state engine calibration including component and system characterisations. The following four calibration tasks, two dynamometer and two vehicle based for a naturally aspirated 2.0L I4 gasoline engine will then be presented in detail with regards to reducing engine out and tailpipe emissions.
Exhaust Gas Recirculation (EGR)- The production of engine torque, combustion stability and emissions models are used to optimise the EGR calibration to improve engine out NOx emissions and fuel economy. A detailed discussion of the model and calibration generation will be presented.
Transient Operation- A significant area of engine calibration is the transient response including both throttle movement and engine warm up effects on the ability of the ECU to limit the AFR excursions from stoichiometric operation. The paper will present the methodologies developed with which to capture and model the engine transient responses using techniques similar to the steady state mapping processes.
Catalyst Light Off and Emissions Feasibility- Design of experiments and statistical modelling were used to optimise the catalyst light off and to evaluate its emissions feasibility and performance early within a calibration programme. Practical results from a production programme will be presented and discussed.
3-Way Catalyst Control & Conversion Efficiency- In order to optimise three-way catalyst conversion efficiency a DOE was specified to view the interaction of the AFR excursion, frequency of excursion and lean/rich operational bias could be identified so that the emissions conversion efficiencies could be maximised. This paper presents practical applications from a calibration engineers viewpoint of using a model based calibration approach to the reduction of engine out and tailpipe emissions. The software used was an industry standard, commercially available package, which can complete the experimental design, modelling and calibration generation. The benefits of the calibration methodologies utilising models enable the calibration engineer to evaluate the driveability and emissions compromise with no additional testing.