Attempt of injectors failure detection based on measurement of the angular speed discrete value

The paper presents results of the experiment focused on detection of faulty injector of medium speed diesel engine, in way of analysis of IAS (Instantaneous Angular Speed) of the crankshaft. The experiment was carried out at laboratory stand in Gdynia Maritime University, equipped with diesel engine Sulzer 3AL 25/30 driving electrogenerator. Sulzer 3AL 25/30 is three cylinder, medium speed, four stroke marine diesel engine, with maximum output 400 kW at 750 rpm. In order to evaluate of IAS utility for diagnosis of the engine, two kinds of wrong adjustment of fuel injection valve’s spring were simulated. First malfunction was too weak spring (initial tension of 15.0 MPa against 25.0 MPa in normal condition), the second was too strong tension of the spring (35.0 MPa). The base of experiment was to angular speed recording, in three different conditions of the engine: healthy one and with two simulated malfunctions. Measurements were carried out at two different loads, respectively 150 kW and 250 kW. The IAS was measured and recorded by the measurement system ETNP-10, which mode of operation was based on perforated disc mounted at the shaft and photo-optic sensor counting laser impulses. Noise decomposition of measurement results was based on triple smoothing using Savitzky-Golay filter. IAS runs of faulty engine were compared with healthy engine measurement, in order to detect all deviation from normal condition