Research of combustion system with semi-open combustion chamber in a commercial spark ignition engine

During the research of a new combustion system with semi-open combustion chamber for SI engines with use of the rapid compression machine (RCM) and visualisation experimental engine (VEE) it was proved that the application of this system results in shortening of the combustion time, increasing of the maximum cycle pressure and, in effect, increase of the combustion efficiency. The aim of the research using a commercial spark ignition engine was to prove that the similar results (as in RCM and VEE) could be obtained in a wide range of automotive engine operating parameters. In this research the two cylinder, four-stroke air-cooled SI engine, with volume displacement 650 cm³ from Fiat 126 motorcar was used. This engine was fitted with a modified cylinder head and ignition distributor. Two types of prechamber with different shape were installed in different locations into the cylinder head but the ignition distributor had fixed, preadjusted, ignition advance angle in the full range of engine speed. The wide-open throttle characteristics including power, specific fuel consumption and exhaust emission versus engine speed and load characteristics including: specific fuel consumption and exhaust emission versus engine torque were determined for different ignition advance angles. In the lower range of the ignition advance angle the engine showed stable operation at lower speed but unstable at high speed and, inversely, if the ignition advance angle was high the engine operation was stable at the higher speed and unstable at the lower. The engine characteristics during unstable operation were deteriorating. The research results show that improvement of the engine characteristics can be obtained in the full range of operating parameters if the ignition advance angle is varied continuously with the variation of engine speed. The ignition advance angle for the engine fitted with the new combustion system, which was subject of this research, was different form the ignition advance angle for standard engine.

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Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.