Smart actuators - Valve Health Monitor (VHM) System

摘要

The health of electromechanical systems (actuators) and specifically of solenoid valves is a primary concern at Kennedy Space Center (KSC). These systems control the storage and transfer of such commodities as liquid hydrogen. The potential for the failure of electromechanical systems to delay a scheduled launch or to cause personnel injury requires continual maintenance and testing of the systems to ensure their readiness. Monitoring devices need to be incorporated into these systems to verify the health and performance of the valves during real operating conditions. It is very advantageous to detect degradation and/or potential problems before they happen. This feature will not only provide safer operation but save the cost of unnecessary maintenance and inspections. Solenoid valve status indicators are often based upon microswitches that work by physically contacting a valve's poppet assembly. All of the physical contact and movement tends to be very unreliable and is subject to wear and tear of the assemblies, friction, breakage of the switch, and even leakage of the fluid (gas or liquid) in the valve. The NASA Instrumentation Branch, together with its contractor, ASRC Aerospace, has developed a solenoid valve smart current signature sensor that monitors valves in a noninvasive mode. The smart system monitors specific electrical parameters of the solenoid valves and detects and predicts the performance and health of the device. The information obtained from the electrical signatures of these valves points to not only electrical components failures in the valves but also mechanical failures and/or degradations.