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This study describes the design and proof-of-concept testing of a system which has enabled sub-zero cold starting of a port-injected V6 engine fuelled with M100. At -30°C, the engine could reach running speed about 5s after the beginning of cranking. At a given temperature, starts were achieved using a fraction of the mixture enrichment normally required for the more volatile M85 fuels. During cold start cranking, firing is achieved using a high energy plasma jet ignition system. The achievement of stable idling following first fire is made possible through the use of an Exhaust Charged Cycle (ECC) camshaft design. The ECC camshaft promptly recirculates hot exhaust products, unburnt methanol and partial combustion products back into the cylinder to enhance combustion. The combined plasma jet/ECC system demonstrated exceptionally good combustion stability during fast idle following sub-zero cold starts.

Examination is made of the changes that take place in the major parameters of the combustion process and engine performance when using three different designs of plasma jet igniters of the open cavity type in a methane fuelled single cylinder engine. The characteristics of the combustion process were analysed employing a two-zone diagnostic model based on cylinder pressure-time development data. The use of plasma jet igniters with methane as a fuel enhanced the rates of burning in the initial stages of combustion, especially with very lean mixtures. The lean limit of engine operation was also extended. Their use for near stoichiometric fast burning mixtures tends in comparison to contribute little towards enhancing engine performance.

The use of cylinder pressure transducers in engine control systems will permit optimum performance under all operating conditions. Previous research has shown that it is possible to automatically detect and evaluate knocking combustion based on low frequency (1 point per crank angle degree) pressure data from research and production engines. However, the previous work was done in a single cylinder research engine and a production engine with relatively slow combustion and large knock pressure peaks. In this study, a spark-plug-mounted pressure transducer and an in-cylinder flush mounted pressure transducer were used to monitor the combustion pressure in a modern four cylinder engine during knocking and normal full load operation over a speed range of 1800 RPM to 4000 RPM. This engine features much more rapid combustion and much smaller knock pressure peaks.

In a previous paper, a knock indicator based on the third derivative of the cylinder pressure trace has been developed. This knock indicator measures the rate at which pressure trace curvature changes from positive to negative during the knock peak. Since it is dealing only with the general shape of the pressure trace, it gives a measurement of combustion severity based on low frequency data such as is commonly used for engine cycle analysis. This low frequency sampling makes it useful for adding knock analysis to existing engine analysis programs without changes of equipment or significant increases in computational effort. It may also make it useful for future on-board engine controls using limited frequency response or heavily filtered pressure transducers. Results of using this knock indicator as a diagnostic tool on a multi-cylinder engine with a spark plug-mounted transducer are presented.

THE WORK REPORTED in this paper is part of an on-going study of cyclic variability in spark-ignition engines. In order to analyze knock and its variability from cycle to cycle in a meaningful way, an algorithm has been developed to characterize the severity of the bulk pressure change associated with knocking combustion. This algorithm depends on the third differential of pressure over the period when autoignition might occur. A large negative value of third differential indicates the abrupt pressure rise and narrow pressure peak commonly associated with end gas autoignition. This knock diagnostic has the advantage of working on a low frequency data acquisition rate (1 point/CA° or less) and of producing consistent results in spite of high frequency noise on the pressure signal such as might be caused by resonance of a spark plug-mounted pressure transducer.

A timed high energy spark discharge system was used as an aid for low temperature starting of two single cylinder, and one multi-cylinder Diesel engines. The tests were conducted by cold soaking the engines in a low temperature chamber in temperatures down to −55°C. An Arctic (AA) Diesel fuel was used at these low temperatures while '(Ho 2) fuel was used at warmer temperatures. When used in I.D.I, engines the timed spark discharge system produced more rapid starts and faster warm ups at lower temperatures and consumed equal or less electrical energy when compared to the factory fitted electric glow plugs. An in cylinder glow plug, which was fitted to a D.I. engine, but is not a factory option, produced more rapid starts than the timed spark discharge, but the timed spark system produced smoother running and consumed only one-half the electrical energy.

Performance of an array of plasma ignition systems has been studied in a CFR engine.This included a standard spark plug, an extended spark plug, a surface discharge plug, and two plasma jet ignitors, one with open cavity and the other with cavity provided with a jet forming orifice.For all the tests the engine was run at a compression ratio of 3:1, a wide open throttle, and minimum for best torque (MBT) ignition timing. In this way specific information was obtained on ignition delay, duration of the exothermic combustion process, engine efficiency, and pollutant emissions.The study demonstrated the effect of various ignition systems on engine performance as the lean operating limit is approached.

This paper is based upon the premise that the best way to deal with current constraints imposed upon car engines is by technological advances designed to (1) minimize pollutant emissions, (2) maximize engine efficiency, and (3) optimize tolerance to a wider variety of fuels. A sense of direction for such advances is derived from a critical assessment of the fundamental advantages of reciprocating I.C. engines as prime movers for automobiles, and the review of their recent developments. On this basis it is shown that major impact in this respect could be made by control1ed combustion. Intrinsically, this should involve proper handling of active radicals, the essential elements of the combustion reaction. Practically, this can be achieved by a variety of means, such as charge stratification, exhaust gas recirculation, homogeneous lean burn, combined with enhanced ignition and enhanced auto-catalysis.

The development of lean charge, fast burn engines depends crucially on enhanced ignition, since one can obtain thereby proper means for increasing the rate of burn in mixtures characterized notoriously by low normal burning speeds. Enhanced ignition involves not only high energies and long duration of ignition, but also a wide dispersion of its sources, so that combustion is carried out at as many sites throughout the charge as possible. Upon this premise, various ignition systems for I.C. engines, operating with premixed charge, are reviewed. The systems are grouped within the following categories: (1) high energy spark plugs; (2) plasma jet igniters; (3) photochemical, laser, and microwave ignition concepts; (4) torch cells; (5) divided chamber stratified charge engines; (6) flame jet igniters; (7) combustion jet ignition concepts; (8) EGR ignition system.

Preliminary test results are presented for an S.I. engine which used a focused laser beam and conventional spark ignition as ignition sources. The results show that for a steady running single-cylinder engine with MBT spark timing and fixed throttle position, engine performance and efficiency are improved, extension of the lean limit of operation by 5 air-fuel ratios is possible, and more NO is produced with laser ignition. The effects of EGR are also examined. The CO and HC emissions are essentially the same. With the laser, the spark location was found to have little effect on performance except when it was moved near the combustion chamber wall. The minimum laser pulse energy required for steady engine operation seems to be dictated by the minimum energy required to achieve breakdown of the laser pulse in air at the same pressure.