Vibrational characterization (nodal analysis) of a Mercedes 220D diesel engine with and without Pantone system Tests from 5 to 7 March 2007 at theIUT Roanne in the Laboratory of Analysis of Signals and Industrial Processes.
Three accelerometer sensors are placed on the bolts of the cylinder head. They are respectively located above the 1, 2 and 4 cylinders. A fourth accelerometer is placed on a rib of the engine block in front of the 1 cylinder. Finally, an inductive sensor is fixed at the starter ring.
Signal processing from the inductive sensor
From the signal of the inductive sensor, we estimate the instantaneous speed of rotation of the motor shaft.
We sample this velocity in the angular domain and calculate the synchronous average at the motor cycle representative of the average velocity variations in the cycle.
If there is little difference in the first peak corresponding to the shocks due to the combustion of the 1 cylinder, on the other hand, there is an almost total disappearance of the second peak which can correspond to the shocks produced by the tilting of the piston. This phenomenon also seems to appear on the 2 cylinder even though it is much less obvious.