Condition Monitoring of Thermal Reciprocating Engines Through Analysis of Rolling Block Oscillations

This paper presents a diagnostic technique for the detection of some faults in internal combustion engines based on analysis of rolling block oscillations produced in engines mounted on elastics supports (used to minimize the transmission of vibrations). Therefore, the block (assumed as a rigid body) has some freedom of movement which becomes manifest through oscillations with respect to an axis approximately parallel to the crank-shaft. These oscillations can give information about possible failures, specially those which are related to the differences in the behavior among the cylinders.

With these considerations, a method has been developed that allows an approximate determination of the instantaneous crankshaft torque through the measurement of rolling block oscillations. These oscillations can be calculated from the measurement of tangential acceleration in a block point which allows the calculation of block angular acceleration.