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Cylinder-by-cylinder variation control is an important issue to the solenoid-based electronic diesel engines. Large variation causes bad engine performance and should be avoided. This paper presents the research results achieved by the author on the issue of cylinder-by-cylinder closed-loop feedback control of diesel engines. Momentary flywheel speed is processed to estimate the cylinder-by-cylinder variation. Utilizing a special signal modulation technique, the new cylinder-by-cylinder variations detection algorithm is worked out, which has a good adaptive capability to fluctuation characteristics of the momentary flywheel speed under variant operating conditions. This algorithm extends the variations detection range from the low speed and steady state engine conditions to the whole engine steady operating condition of the engine and some transient conditions. The closed-loop control of the cylinder-by-cylinder variation is carried out on the engine test bench.

Momentary camshaft speed signal of in-line fuel pump of diesel engines is investigated in this paper. First, time domain characteristics and frequency characteristics of camshaft speed are analyzed. Secondly, the relation between momentary camshaft speed and fuel pressure in the pump is studied. The work indicates that pulsed fuel pump pressure is a result of camshaft speed fluctuation. Thirdly, the relation among momentary speed fluctuations, different injection timing and injection duration are studied. Correlation of the fluctuation amplitude and injected fuel quantity is calibrated. The basic results show that it is possible to estimate cylinder-by-cylinder fuel injection quantity. Finally, the relation between camshaft dynamics and pump cam profile design is discussed. The results indicate that momentary camshaft speed is a useful signal for injection system design, diagnosis and control.