Model-Based Fault Detection for Hydraulic Servoproportional Valves

Abstract

This paper presents a mathematical model for online fault detection on single solenoid servoproportional spool valves. The most common failures as well as its effects on the valve behavior are studied and took into account for the model representation. Servoproportional valves are used in industry, aerospace, and military fields. Some of these uses are criticalmission, where the valve must not fail without previous warning to prevent or mitigate financial losses, equipment damage, and risk to personnel. Even in less demanding applications, it is very useful to be able to quickly locate a failure in the hydraulic circuit, which is a task that may demand up to 80% of the time used in corrective maintenance. Total failure can readily be detected using the signals available on the valve electronics. However, since the spool positioning is on closed loop on these valves, incipient failures that can be overcome by the controllers cannot be easily detected. In this paper, an experimentally validated analytical model is used as a reference model such that the solenoid actual current can be compared with the theoretical current. Since the valve hysteresis is considered, the model calculates maximum and minimum current values that correspond to an undamaged valve. Experimental results with a standard valve and a damaged valve show the effectiveness of the model for fault detection.

Fault Detection and Diagnosis Methods for Fluid Power Pitch System Components—A Review

“…Ramos Filho and Negri [28] describes a model based approach to fault detection of a hydraulic proportional valve. A physical model is used as a reference such that the measured current can be compared to a theoretical value.…”

“…Ramos Filho and Negri [28] faulty spool model based i v Exp. Jouppila et al, [29] inc. friction model based i v and V v Sim.…”

Online fault detection system for proportional hydraulic valves

“…The usual hysteresis exiting in proportional valves determines the position upper and lower limits that can be occurred for a specific input control signal value. Hysteresis is a consequence of two main factors: the non-linear friction between spool and sleeve and the remanence phenomenon associated with the proportional solenoids [9,17,18]. The characteristic of the valve null region can Fig.…”

“…The capability of fault detection mechanisms sensible to friction, fatigue of springs, and wearing in valves has been studied through simulation. [9] presented a model-based fault detection approach for single solenoid servoproportional valves. The proposed model estimates adequately the solenoid current of a servoproportional valve establishing minimum and maximum steady-state current limits for an undamaged valve.…”

“…Forces over the valve spool are significantly related to internal flow forces that, in its turn, are influenced by the pressure drops and fluid temperature [9,13]. Therefore, the valve thresholds must be determined considering all steady state and dynamic operational conditions that the valve will be subject to during its use.…”