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EN
The subject of the analysis presented in the paper is the idea and implementation method of the ignition point of homogeneous air-fuel mixture, used in the IC engine with HCCI system. Autoignition of the combustible mixture can occur only upon reaching the characteristic self-ignition temperature Tz. It should take place during (near end) the load compression. In order to achieve the fuel mixture ignition temperature Tz in the system, usually it is proposed adjusting the engine compression ratio, epsilon. However, it is quite cumbersome especially in case of frequent changes of engine load (there are also difficulties with the precise advance angle adjusting of fuel mixture ignition). According to our conception, the other method of autoignition adjustment can be successfully applied. The essence of the new idea consists in proper selection, according to engine load, of the exponent k of charge polytropic compression. Introducing the defined dose of monoatomic gas (e.g. argon Ar,k almost equal 1.667) to air-fuel mixture, the higher values of the polytropic compression exponent .. of working medium can be achieved. It will result in significant increase of the temperature rise Delta Tmax of the compressed charge and accordingly progressive increase of the advance angle of the mixture ignition.
EN
Lean fuel/air mixtures with various fuel/fuel ratios between methane and n-butane were supplied to a premixed compression-ignition engine (i.e. homogeneous charge compression ignition engine, HCCI) with or without supplementary gaseous formaldehyde induction as an ignition controlling additive. In the no additive case the methane and butane function as the two fuels in the high/low-octane two-fuel premixed compression-ignition operation we proposed previously as another ignition control procedure. The formaldehyde addition to the methane/ butane/air mixtures has given the engine desired and stable ignition timings controllable by the amount of formaldehyde to be added, almost independent on the fuel/fuel ratios between methane and butane. The efficacy of formaldehyde has been confirmed as an ignition controlling medium for the piston-compression ignition of hydrocarbon/air mixtures.
EN
A criterion between success and failure of marginal fuel/air compression ignition was searched for using a rapid compression machine. A barely achieved ignition process was compared to a case no ignition was established due to a slightly insufficient compression pressure level. The differential on the chemical species histories during the induction periods between both cases was examined by continual different-timing gas samplings. A distinguished difference could be found only on the carbon-monoxide/carbon-dioxide ratio between the flammable and nonflammable critical conditions. The ratio increased continuously in the ignition success cases. There were no differences in other species concentration, such as gaseous water, hydrogen, formaldehyde and ethylene . At the time just before the final hot-flame onset the carbon-monoxide concentration came up to around 7 000 ppm, independent of the mixture strength. A steady carbon-monoxide/carbon-dioxide ratio was observed in the case no hot-flame onset was established. Continuous growing of carbon monoxide during the blue-flame period would be an indication for the transfer to the final hot-flame ignition.
PL
W pracy przedstawiono możliwości wykorzystania zbudowanego mikroprocesorowego sterownika silnika ZI. Przedstawione zostaną przykładowe algorytmy sterowania, umożliwiające wprowadzanie korekcji charakterystyk wyprzedzenia zapłonu i czasu wtrysku silnika w zależności od zmian warunków pracy.
EN
The paper presents possibilities offered by the application of an elaborated microprocessor controller for spark-ignition engines. Example control algorithms that make possible to introduce corrections to the characteristics of ignition advance and injection time depending on varied operation conditions have been presented.
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