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Significant differences have been observed in the behaviour of elastomeric seals exposed to various automotive diesel fuels. This behaviour is governed not only by the chemistry of the elastomer but also by the aromatic content of the fuel and is typical of elastomer/fluid interactions occurring under diffusion control. Although no significant differences were observed in the response of nitrile elastomers exposed to peroxides, the use of antioxidant additives in “low” aromatic diesel fuel needs to be considered. The normal seal housing design criterion is such that seal integrity should not be compromised by the use of “low” aromatic fuels in normal operating circumstances. Some three years' experience in the Swedish market supports this view.

This paper gives an account of the work which was performed by members of a Committee of the International Organisation for Standardization, “Injection Equipment and Filters for Use On Road Vehicles”, directed towards a lubricity standard for diesel injection equipment calibration fluid. Problems of surface damage had arisen with some designs of pump during the period of running in, which occurs when pumps are calibrated at the end of the manufacturing process. It was proposed to give protection against such damage by the use of an Extreme Pressure (anti-wear) additive in the calibration fluid. The objective of the work was to define a procedure, using a four-ball test machine, which would enable a standard to be set for a calibration fluid incorporating an anti-wear additive. It was found that it was not possible to set such a standard due to the inconsistencies between test machines, even with the use of a reference fluid.

The introduction of electronically controlled fuel injection equipment for diesel engines has generated a need for a tool to develop electronic governor control algorithms. It is possible to execute such development by building a flexible control system and experimenting with the control variables on an actual engine, but this is a time consuming and expensive process and the need has arisen for a computer simulation of an engine to expedite such work. Many engine simulations written for such purposes rely on the concept of a fluctuating, but continuous, energy input to an engine which in turn accelerates after a fixed time delay representative of the combustion process and the variable leverage of the connecting rod and crank system. Such a simulation neglects the aliasing errors that can arise if governor actuating frequencies coincide with or exceed fuel injection frequencies, in which case the continuous mode of simulation becomes invalid.