Diagnosis of alternative internal combustion engines through analysis of block oscillations

Abstract

This article presents a non-intrusive technique, designed for the Predictive Maintenance of alternative internal combustion engines (MCIA), based on the analysis of the oscillations of the block assuming the motor as a rigid body supported by elastic springs.These considerations allow The approximate determination of the instantaneous torque of the motor, using only and exclusively an accelerometer installed at a point of the block as far as possible from the crankshaft and recording the time signal of several thermodynamic cycles The signals thus obtained can inform about different types of failures, Especially those related to the different behavior between the cylinders.
A simple physical model was used to estimate the performance of the engine under different operating conditions. The model has been validated through the realization of different experimental measurements both in engine test bench and in engines in service. Different tests have also been carried out to analyze the influence of the accelerometer position on the block.
The final objective of the study is to determine alert and alarm limits of certain failures in the engine, such as injection or abnormal combustion in one or several cylinders. For this, it is necessary to analyze both the temporal and the frequency domain, a significant difference with the other techniques used for the diagnosis of machinery through vibrations.