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1 High precision high pressure diesel common rail fuel injection systems play a key role in emission control, fuel consumption and driving performance. Deposits have been observed on internal injector components, for example in the armature assembly, in the slots of the piston and on the nozzle needle. The brownish to colourless deposits can adversely impact driveability and result in non-compliance with the Euro 4 or Euro 5 emission limits. The deposits have been extensively studied to understand their composition and their formation mechanism. Due to the location of these deposits, the influence of combustion gas can be completely ruled out. In fact, their formation can be explained by interactions of certain diesel fuel additives, including di- and mono-fatty acids. This paper describes the methodology used and the data generated that support the proposed mechanisms. Moreover, approaches to avoid such interactions are discussed.

The control of fuel delivery to minimize drivetrain oscillations is a major benefit to vehicle refinement and driveability. This paper describes the application of robust H-infinity loop-shaping control to the speed-fuel control loop. A one-degree-of-freedom controller structure (feedback only) is examined and applied to a small passenger car. Using careful implementation, the control algorithm is of low order and efficient requiring only limited microprocessor resources. The robust controller gives excellent performance when operated synchronously to engine rotation, where the dynamics become speed-dependent. Alternatively it can be operated satisfactorily at a fixed sample rate, asynchronous to engine rotation. The design is found to be eminently suitable for production.

This paper describes the application of robust H-infinity loop-shaping control to diesel engine speed control for the driven idle condition. The method was introduced in a previous paper1 and applied to an anti-oscillation strategy. For this paper, a one-degree-of-freedom controller structure (feedback only) was examined and applied to a small passenger car. Through careful implementation, the control algorithm was made to be low order and efficient, requiring only limited microprocessor resources. The robust controller design was evaluated through simulation and vehicle testing, and the performance was compared with an up-to-date tuned PI controller. The success of the robust controller was demonstrated in vehicle testing for the most challenging 3rd gear condition. The design was found to have superior performance and was eminently suitable for production.