Search Results

For many years, compression ignition combustion has been studied by a combination of generic studies on fuel spray formation and analysis of results from single and multicylinder engines. The results and insight have been applied to design and develop advanced fuel injection equipment for high-speed direct injection engines. Experimental fuel injection equipments, including early common rail designs, have been matched to combustion chambers in single cylinder research engines to tackle the conflicting requirements of efficiency and minimum nitric oxide formation, combustion noise and soot. A clear strategy evolved from the work with experimental equipment that is being applied to multicylinder engines. If sufficient oxygen is available in the gas charge trapped in each cylinder, the LDCR common rail injection system will provide the fuel required to develop high torque at low engine speeds.

Performance and refinement are key factors which influence the market acceptance of passenger cars, and consequently in the area of diesel fuel injection control there is increasing pressure for improved driveability. “Driveline shunt” is one important and problematic aspect of driveability, which is also known as “judder”, “chuggle” or “cab-nod”. It has been defined as an objectionable vehicle oscillation which takes place following a rapid throttle input or increase in engine load. This phenomenon is caused by driveline vibrations which can occur as a consequence of variations in engine torque demand. Mathematical modelling and experimentation techniques have been used to establish the behaviour of a fuel injection system, engine and vehicle driveline. Vehicle tests have been conducted in order to relate objective metrics and subjective opinion.

An advanced catalytic exhaust after-treatment system addresses the problem of NOX emissions from heavy-duty diesel trucks, relying on real-time catalyst modelling. The system consists of de-NOX catalysts, a device for injection of a reducing agent (diesel fuel) upstream the catalysts, and computer programmes to control the injection of the reducing agent and to model the engine and catalysts in real time. Experiments with 5 different air-assisted injectors were performed to determine the effect of injector design on the distribution of the injected diesel in the exhaust gas stream. A two-injector set-up was investigated to determine whether system efficiency could be increased without increasing the amount of catalyst or the amount of reducing agent necessary for the desired outcome. The results were verified by performing European standard transient cycle tests as well as stationary tests.