Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Electronic engine control systems utilise tables, or maps, of data to determine
the set-points of the various actuators on the engine and to calculate the values
of variables that cannot be directly measured. To ensure accurate control of the
engine processes the values in these maps have to be accurately calibrated for the
particular engine being controlled.
Due to the complex interaction of the various systems in the engine it is becoming
more and more difficult for human calibration engineers to be able to take all
the effects of changes to a particular parameter into account. This problem is made
worse by increasingly strict emissions regulations and performance demands
from the customer. The process of calibrating the maps in an Electronic Control
Unit (ECU) is also very resource intensive since it involves taking a test engine
installed in an engine test cell to every operating point on the various maps and
adjusting the map values until the desired response is achieved.
The aim of this project was to develop a solution to this problem in the form of a
simulation based calibration system. The proposed system would use an accurate
model of the engine to simulate the effect of various map values on the engine
response. This data would then be used to find the map values that would enable
the engine to deliver a desired torque curve. In the case where it is not practical to
use engine simulation the system would be able to process a database created by
testing an actual engine. This testing could also be automated.
To achieve this aim the AutoCal program was created. This program can manage
a commercial engine simulation code to create a database of the effect of various calibration values on the engine response. It can then evaluate the created database
subject to user defined operating constraints and find calibration values that
will deliver a desired torque curve. It can also be used to evaluate and process
databases created by engine testing.
To provide the data required for the development and testing of the AutoCal
program, a naturally-aspirated engine was turbo-charged and tested at various
operating points. The resulting data was used to calibrate and validate a model
of the engine created and simulated with the WAVE software package from Ricardo.
The project was focused on finding calibration values for the maps used to control
the turbo-charger wastegate and ignition timing of the test engine. Work was
limited to the full load operating region and fixed Air/Fuel Ratio (AFR) values
were used.
The project showed that simulation based calibration can be used to calibrate
control system maps once an accurate model of the engine being controlled has
been created. Very useful insight was gained into the process of building, testing
and modelling a turbo-charged internal-combustion engine and calibrating modern
electronic engine control systems. The end result is a useful engineering tool
with the following functions:
² Automatically simulating the effect of various control inputs on engine performance.
² Determining the correct calibration settings to deliver the desired performance
subject to user-definable constraints. This can be done using results from
simulation or physical engine testing in the case of simulation tools not being
available.
² Providing the data required when calibrating the engine model used during
simulation by processing and displaying the outputs of the simulation program
compared to test data.
² Plotting any test or simulation results in a format configured by the user.
Using this tool facilitates a more structured and less resource intensive approach
to engine control system calibration. / Imported from http://etd.sun.ac.za April 2010. / np2010
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2599 |
| Date | 12 1900 |
| Creators | Pienaar, Schalk Willem |
| Contributors | Taylor, A. B., Von Backstrom, T. W., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 3467162 bytes, application/pdf |
| Rights | University of Stellenbosch |
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