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Electrical on demand supercharging provides an internal combustion engine with the facility to increase its volumetric efficiency without being subject to the mechanical constraints associated with a conventional pressure charging device. This enables improvement in fuel economy through engine downsizing with the added ability to enhance torque. The Visteon Torque Enhancement System (VTES) is a fully integrated air management system, at the heart of which is an electronically controlled, electrically powered supercharger. Based on the driver demand, the supercharger responds by rotating a compressor at a speed which pressurizes the intake air to the desired level. The control system associated with an electrical boosting device (EBD) considers the engine and electrical motor torque requirements for providing the actuator with an appropriate compressor set-point. Optimal tracking of the set-point requires inclusion of physical limits of the actuator for the supercharger operation.

Spark plug fouling is a common problem when vehicles are repeatedly operated for very short periods, particularly at low temperatures. This paper describes a test procedure which uses a series of short, high-load drive cycles to assess plug fouling under realistic conditions. The engine is force cooled between drive cycles in order to increase test throughput. Spark plug resistance is shown to be a poor indicator of the effect of fouling on engine performance and the rate of misfiring is given as an alternative measure. An automated technique to detect misfires from engine speed data is described. This has been used to investigate the effect of spark plug type, fuelling level and spark timing on fouling. Spark plugs which are designed to run hotter are found to be more resistant to plug fouling. Isolated adjustments to fuelling level and spark timing calibrations within the range providing acceptable performance have a weak effect on susceptibility to plug fouling.

Spark ignition engines for automotive applications must have good cold start performance characteristics at sub-zero ambient temperatures. Satisfactory performance is most difficult to achieve at the lower end of the temperature range, typically around -30°C. The start characteristics of a particular engine depend on basic design features, starter motor characteristics, and the calibration and strategy used to regulate fuel supply during start up. The paper reports a computational model which enables the investigation of these with the minimum of experimental data. The model has been developed to run on desk-top PC machines, specifically as a CAE development tool. The formulation of the model and the experimental tests were used to generate the input data required for particular applications are described.

Optimising an engine specification to improve cold start performance has been investigated. Taguchi methods were used to define a test programme to assess the effect of seven build factors. Experiments were conducted to measure mixture ratio at the spark plug location after a short period of engine cranking at test conditions covering ± 15°C and three fuel-mass-supplied values. The analysis of the results identified build modifications which improved start quality and reduced HC and CO emissions substantially compared to a reference, base-line build. Injector design and location, and inlet valve timing were found to have most influence on robustness to uncontrolled variations in mixture preparation during starts.

The paper exemplifies the necessity to quantify the various noise sources present in modern automotive engines. Results demonstrate the non-linearity problems associated with many of the non-running engine rig tests currently in use. A new technique is described for combustion induced noise simulation using hydraulic excite ion. Results obtained using this experimental method are compared with those measured on the running engine.

The paper describes the assessment and testing of two high speed diesel engine structure modifications designed to reduce noise. The modifications tested are a five main bearing version of a standard three main bearing engine and the addition of a sump plate. The results indicate that it is difficult to assess the running engine vibration and noise characteristics using modal analysis techniques but that this is possible when using the banger test techniques. It is shown that noise reductions up to some 4.0 - 5.0 dBA can be achieved both on the test bed and in the vehicle application.