Use of phase portraits of hydro-mechanical units for diagnosing aircraft hydraulic systems

Abstract

The article deals with diagnostics of hydraulic systems using phase portraits. A brief review of the existing methods for diagnosing hydraulic units identifying their advantages and disadvantages is given. An approach based on the analysis of dynamic characteristics of a hydraulic system and phase portraits of hydro-mechanical units in their operational and faulty conditions is proposed. As an example, we consider a dynamic model of a simplified hydraulic system consisting of standard components. By adjusting the model parameters characteristic faults typically occurring in operation, such as internal leaks in the pump, contamination of the hydraulic fluid with mechanical impurities, sticking of the valve, etc. were artificially introduced in hydro-mechanical units. A family of phase portraits of a hydraulic system for the operational condition and various faulty ones was constructed. A quantitative estimate of their changes, based on calculating the difference in the areas of the figures restricted by their graphs, is proposed. As a result, it was established that failures and malfunctions introduce changes in the phase portraits of hydro-mechanical units, which makes it possible to apply the proposed approach as a basis for diagnosing the technical condition of hydraulic systems.

Imitation models of aircraft hydraulic units with account for typical faults

“…С другой стороны, при появлении неблагоприятных факторов (наличие эксцентриситета и нарушение цилиндричности поверхностей золотника и гильзы) в паре появляется неуравновешенная радиальная сила, стремящаяся сместить золотник к гильзе, тем самым вызывая недопустимое увеличение сил трения в паре и в итоге заедание золотника в гильзе. Механизм развития данного процесса рассмотрен в [18].…”

“…Полученные результаты подтверждают возможность использования предложенного подхода для качественной (по характеру отклонения ДП от эталона) и количественной (например, при помощи способа, предложенного в работе [18]) идентификации неисправностей ГС.…”