Analysis of the possibility of using crankshaft instantaneous angular velocity measurements to assess the tightness of the engine combustion chamber

The results of experimental studies on the influence of combustion chamber tightness on the crankshaft rotational (angular acceleration) profile of an AD 4.236 engine are presented. Based on the obtained results, a diagnostic method for determining cylinder compression pressure is proposed. During the operation of a reciprocating internal combustion engine, wear processes occur in the components forming the working space. As a result, there is a decrease in the tightness of the combustion chamber, which causes, among other things, a change in cylinder filling, a reduction in compression pressure, and an increase in engine oil consumption. This leads to a deterioration of the main engine performance parameters and indicators – a decrease in power (torque), an increase in fuel consumption, and an increase in the emission of harmful exhaust components. Hence, it is generally considered that the tightness of the combustion chamber determines the engine’s durability (the period until reaching the limit wear value – compression pressure), which for modern passenger car engines is 250,000 to 400,000 km, and for trucks even up to 1 million km [2, 3].
There are over a dozen methods for assessing combustion chamber tightness. All of them are indirect methods, meaning they provide information about the value of a measured diagnostic parameter that depends on the degree of tightness. (…)

Analysis of the possibility of using crankshaft instantaneous angular velocity measurements to assess the tightness of the engine combustion chamber – PDF file for download