Condition Monitoring in Diesel Engines for Cold Test Applications. Part I: Vibration Analysis for Pass/Fail Decision.

In this paper the characteristics of the cold test technology will be described and a monitoring method for quality tests of diesel engines at the end of assembly line will be considered. A variety of different techniques for processing vibration signals has been proposed by many researchers but only a few applications in cold test monitoring exist. The determination of reliable threshold values for pass/fail decision through the calculation of global parameters which describe the PDF (Probability Density Function) of the vibration signal in the time domain is the goal of this work. Experiments on normal and faulty engines were carried out in order to develop this approach. In particular, eight different faults were artificially introduced and the influence of the operational speed during tests is investigated. Furthermore, a comparison between measurements concerning vibrations, pressure and torque is shown and discussed.