Evaluation accuracy of combustion chamber tightness in piston engines, on the basis of a developed indicator diagram

The following article describes the effect of combustion chamber leakage of piston engine on the quality of its performance. To make a diagnosis of combustion chamber tightness, only such parameters were selected which are characterized by high information value and are closely connected with its defined structure. For this reason such connections are unmistakable, which results in making the right diagnosis of combustion chamber tightness of piston engines. Special attention was paid to the fact, what consequences, combustion chamber leakage, can cause to the piston engine performance. The most dangerous for the engine efficiency is the leakage of combustion chamber. The leakage of combustion chamber brings about the change of such engine parameters as pressure of suction, pressure of final compression and burning and the change of exhaust gases composition, which effect on the engine power and on fuel consumption. Condition of piston rings and their influence on gas pressure in combustion chamber has also been characterized. Pressure of gases taking place in engine cylinder and their connection with leakage of combustion chamber have also been described. The article also exposes random character of combustion pressure in engine cylinder. Besides, the errors of indicator diagrams together with mapping error position GMP have been mentioned too. Reliability of diagnostic parameters of technical condition of combustion piston engines obtained on the basis of developed indicator diagrams has been defined. Such diagram must be made on the basis of measurements and statistic analysis of pressure parameters in correctly adjusted engines, being in perfect technical condition, and not on the basis of measurements obtained in the engine test bench of a new engine. Bad technical condition, especially leaks in its cylinders causes power differences in engine arrangements, which endangers its safe exploitation.