Abstract
This paper presents a non-intrusive fault detection technique for predictive maintenance of Automotive
Thermal Reciprocating Engines, based on the analysis of rolling block oscillations produced in engines mounted on elastic supports and assuming the engine as a rigid body. These considerations allow an approximate determination of the instantaneous crankshaft torque through the measurement -by means of just an accelerometer- of the tangential acceleration in a block point, placed as far as possible from the crankshaft.
These oscillations can provide information about possible failures, especially those related to differences among the behaviour of cylinders.
A simplified physical model of an engine mounted on elastic supports was used in order to estimate the engine behaviour under different operating conditions. This model has been validated with experimental measurements. These experimental measurements have been carried out in a standard experimental engine test bench and in different types of Diesel engines, which are mounted on light and medium automotive vehicles used for passenger transportation. Tangential acceleration measurements in different block points have also been carried out, in order to analyse the influence of the accelerometer position.
The final goal of this study will be to provide awareness and limiting values for certain failures, such as abnormal injection or combustion in one or more cylinders, and to detect the source of these abnormalities by comparing the different behaviour of the cylinders. In order to do this, the time and the frequency domain of the tangential acceleration need to be analysed.