Title

Hardware and Software Design for a Large Gas Engine Detonation Simulator

Publication Date

10-2008

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Computer Engineering

Department

Electrical and Computer Engineering

Major Advisor

Nader Rafla

Abstract

Demands to meet legislative exhaust emission levels, provide fuel economy, and improve engine quality have been the major driving forces for engine control advancement [1]. Benefits of engine control advancement include improved energy efficiency, reduced greenhouse effects and noxious gas emissions, oil change frequencies, and machinery maintenance. Unfortunately these benefits push the limits of engine detonation (often referred to as engine "knock"). The electronic gas engine control system can take measures to avoid the damaging effects of detonation while retaining the benefits of remaining close to detonation boundaries [2]. Leading edge software is being designed and researched to monitor and prevent the occurrence of unwanted engine detonation.

The purpose of this research is to design an engine detonation simulator that can be used to detect undesirable detonation that might occur in gas engines. In this thesis, a large Gas Engine Detonation Simulator hardware and software is designed, implemented, and tested. A program was developed to generate Pulse Width Modulation (PWM) signal whose duty cycle can be changed rapidly via a look-up table. A low-pass filter to act as a Digital-to-Analog Converter (DAC) that converts the PWM signal to a sinusoidal signal was also designed. The generated sinusoid signal emulates the large gas engine detonation sensor feedback signals. The sinusoidal signal was designed to have characteristics that are determined by user input and specific large gas engine needs. The simulator can be easily adjusted to generate different frequencies with adjustable amplitude, and adjustable time lengths or "windows."

Experiments were performed with the Detonation Simulator and a Large Gas Engine Electronic Control Module (ECM). The goal of the experiments was to verify that the simulator correctly interpreted signals from the ECM interface and generated the simulated detonation signals accordingly. Research revealed that the Simulator successfully generated detonation signals that were synchronized with the four-stroke cycle of the internal combustion large gas engine. The simulator was also able to interpret user input to vary the generated signals intensity (amplitude) and ''window'' length times at different engine test speeds.

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