Diagnostic symptoms of piston combustion engines of ship main propulsion received from its developed indicator diagrams

The following article describes parameters of developed indicator diagrams concerning piston combustion engine of ship main propulsion, which can be used to assess its technical condition. To make a diagnosis of the engine combustion only such parameters should be selected which are characterized by high information value, being closely connected with its one defined structure. This is the cause why such connections are of unmistakable character, which allows to make the right diagnosis of technical condition of piston engine. Special attention was also paid to the consequences of diagnostic symptoms qualification from developed indicator diagrams of ship propulsion engine working in different conditions. Deflection of average indicated pressure caused by inappropriate engine performance could be caused by: 1) faulty adjustment of injection pump; 2) leaky combustion chamber, 3) bad technical condition of injection apparatus and the loading air system. Wrong technical condition of the engine caused by a leaky combustion chamber brings about a decrease of its performance. Untight combustion chamber causes the change of such parameters as, suction pressure, pressure of final compression and burning, as well as, the change of exhaust gases composition, which influences the power of the engine and fuel consumption. It has been mentioned what gas pressures of working process in engine cylinders are connected with an untight combustion chamber. Random character of burning pressure course in engine cylinder has also been paid attention to. Reliability of diagnostic parameters of piston engine technical condition received based on developed indicator diagrams have been determined. Diagnostic symptoms have been defined, basing on measurements and statistical analysis of pressure values in the cylinders of properly adjusted engines being in excellent technical condition and not based on measurements received in the engine test bed of a new engine.