Document Type

Theses, Ph.D

Rights

Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence

Disciplines

2.3 MECHANICAL ENGINEERING

Publication Details

A thesis successfully submitted in fulfilment of the requirements for the degree of Doctor of Philosophy

Abstract

The presented work is offering an investigation how the bandwidth of vehicle specific attributes is impacting engine control parameter requirements for warmup control of the catalytic converter, aiming to ease the development process by providing mathematical means for an automatic generation of control settings. For the specific purpose, a novel drive cycle simulation approach is developed, focusing on emission performance and fuel consumption of a gasoline engine. Steady state and quasi steady state measurements are collected to quantify the impact of modifications to control parameters on emission concentration, exhaust gas temperature and engine torque, especially directly after a cold start. A run-time efficient simulation model, based on polynomial equations is set up to generically describe the identified physical and chemical effects. Control system dynamics, warmup effects, control parameter modifications and the interactions of control settings with each other and with engine temperature are considered. A catalytic converter model which is developed in an accompanying work is incorporated to establish comparability of results to vehicle measurements. The model has been extensively correlated to measurement data. Measurement and model are agreeing very well with differences being discussed in detail. To visualize bandwidth dependencies, the model is used to quantify the relationship of vehicle attributes, control modifications and engine performance measures by a linear modulation of the corresponding parameters. Multiple physical and chemical effects are identified that impact the overall emission result independently from each other. While the sensitivity to changing control parameters and vehicle specific attributes is found to vary significantly in magnitude, trends are comparable on the NEDC and WLTC profile. II Transferring the obtained results into mathematical relationships, an offline optimization of engine control parameters based on vehicle specific attributes is attempted which is additionally taking practical feasibility into account. It is demonstrated that a single set of control parameters is fulfilling emission requirements of an entire pre-defined product portfolio without significantly sacrificing fuel economy or robustness. The novel methodology is proposed to be implemented into a standard development process, both for handling product complexity as well as to optimize product cost by actively incorporating controls optimization into hardware design and system layout during an early stage of the development process. Given the consistency and transparency of results, the established methodology is offering significant potential for further academic studies.

DOI

https://doi.org/10.21427/6sx3-r691

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