Masters Theses

Date of Award

8-2001

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

David Irick

Committee Members

Ke Nguyen, Ming Zheng

Abstract

Due to more stringent regulations set forth by the Environmental Protection Agency (EPA) to take in effect in the year 2007 [1], the automotive industry has been required to evaluate new diesel engine technologies to further reduce tailpipe emissions. Of major concern is the reduction of oxides of nitrogen (NOx) and particulate matter (PM). These two emissions are linked to environmental pollution and health concerns respectively. In recent years, the primary method employed to reduce these emissions has been to increase combustion efficiency by increasing injection pressure. These higher injection pressures increase the atomization the fuel by increasing the injection velocity of the fuel droplets into the combustion chamber. These higher injection pressures and velocities have been shown to decrease engine out emissions while increasing power output [2,3]. In addition to higher injection pressures, the electronic control of the fuel injection systems has become necessary to help meet these newer emissions standards. Before the use of electronic fuel injection, the maximum injection pressure was a function of engine speed as well as the camshaft profile that actuated the fuel pump and injectors. Since the introduction of such electronically controlled fuel injection systems, such as the unit injector, unit pump, and distributor pump, pressure generation has been de-coupled somewhat from these constraints. The Robert Bosch Corporation achieved complete de-coupling with the release of the high-pressure common rail injection system for European markets in 1997 and the American market in 2001 [4,5]. This system allows high injection pressure (up to 30,000psi) to be developed at idle engine speeds and maintained throughout the engine's operating range. In fact, optimum injection pressures are available for any operating condition and any engine speed. This system also allows for highly flexible rate shaping of the fuel injection sequence as well as flexible injection timing. The purpose of this study was to develop a test cell that incorporates a high-pressure common rail fuel (HPCR) injection system on a single-cylinder test engine. The intended use of this test cell would be to conduct research in the area of optimizing fuel injection timing, injection rate, fuel pressure generation, and injection length with respect to reducing fuel consumption, tailpipe emissions, reduction of combustion noise, and increasing power. This test cell uses an alternating current (AC) vector controlled motoring/absorbing dynamometer with a Hatz single cylinder direct injection (DI) diesel engine retrofitted with a Bosch HPCR fuel pump, fuel injector, an universal solenoid driver, and a personal computer (PC) based programmable engine control module (ECM).

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