Diagnostic Methodology for Piston Rings Using the Vibroacoustic Method

The article is devoted to a methodology for diagnosing the technical condition of piston rings in the D-240 diesel engine using a vibroacoustic method at cranking speed. The physical basis of piston skewing caused by changes in lateral force due to axial and trans- verse components of inertia, friction, and cylinder pressure is analyzed. It is shown that wear of the piston rings leads to a reduction in friction against the cylinder wall, which in turn lowers the threshold crankshaft rotational speed at which piston skewing occurs and the as- sociated vibroimpulses can be detected. Based on theoretical analysis, an analytical expres- sion for the minimum diagnostic rotational speed is derived and experimentally validated. It has been established that at approximately 90 rpm, piston skewing generates vibrosignals of sufficient intensity for reliable detection and diagnosis of the piston rings’ condition.