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Automated system for diagnosing a cylinder-piston engine group
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
The work is aimed at increasing the reliability, accuracy, information content and depth of the process of diagnosing a cylinder-piston engine group. For this, an automated diagnostic system has been developed, which includes a system unit with a monitor, special software for measuring and processing information, a measuring analog-to-digital module, adapters for connecting to the engine. The diagnostic system allows you to record the change in pressure in the cylinder for each degree of rotation of the crankshaft with an error that does not exceed 1.7%. Measurements are performed in test mode, when the crankshaft of the engine is scrolled with a starter. The measurement results are presented in the form of diagrams, text and digital values. The system also allows you to save, reproduce and transmit diagnostic information in digital, graphic and text form. Using the developed diagnostic system, the engines of automobiles of various brands with a compression ratio of 9.5-10.5 units, with a working volume of 1.2-2.8 liters, with two, four and five valves per cylinder were investigated. In the course of experimental studies, the most common failures were: burnout of the exhaust valve, loose seating of the valve in the seat, deformation of the valve stem, violation of the thermal gap in the valve mechanism, seizure on the piston, seizure on the cylinder wall, loss of elasticity or breakage of compression rings, deformation and kink of the piston baffles, wear of the cylinder in the vicinity of the top dead center, wear of the piston rings and piston grooves. Based on the obtained experimental data, an objective relationship is established between characteristic engine malfunctions and diagnostic parameters. The analysis of diagrams of changes in pressure in the cylinder at each degree of rotation of the crankshaft allows the diagnostician to more objectively evaluate the technical condition of parts that ensure the tightness of the engine's operating process.