US 6,205,409 B1 · Predictive failure monitoring system for a mass flow controller

Abstract

By monitoring the output voltage of a mass flow controller (MFC) there is no way to detect when a MFC is starting to degrade (or beginning to fail) as long as the MFC output voltage is driven to match the MFC setpoint voltage. Only when the MFC actually fails, and the MFC output voltage is unable to be driven to match the MFC setpoint voltage, is the failure detectable. A predictive failure monitoring system for a mass flow controller (MFC) is disclosed which monitors the “valve voltage” of the MFC as well as the MFC output voltage. By knowing the normal relationship between the MFC setpoint voltage and the respective valve voltage, then degradation or other changes may be noticed before the MFC actually fails, and importantly, before production material is ruined by the failing MFC. Such a real-time monitoring capability may be transparently implemented as an add-on module between the MFC and the system controller for the MFC. The add-on module may be advantageously connected between the MFC card edge connector and the system card edge socket which is normally connected to the MFC card edge connector. The module monitors, in real time, the performance of the MFC by measuring the valve voltage on the valve test point. If determined to be outside of various user-settable limits, then warnings and relay closures may be done. The module can also automatically characterize the MFC operation when known to be proper, then go into a “run” mode to monitor operation and provide indications when operation falls outside of user-settable limits.

Claims26

Dependent claims

An apparatus for monitoring operation of a mass flow controller (MFC) comprising:

a first interface circuit having a first input for receiving a particular setpoint signal conveyed to the MFC by a control system operably connected to the MFC, and for generating, on a first output of the first interface circuit, a first signal corresponding to the particular setpoint signal, said first interface circuit having a second input for receiving an actual valve control signal generated by the MFC in response to the particular setpoint signal, and generating, on a second output of the first interface circuit, a second signal corresponding to the actual valve control signal;
a storage circuit for providing an expected valve control signal corresponding to the particular setpoint signal received by the MFC;
a comparison circuit for comparing the second signal to the first signal to determine whether the actual valve control signal received from the MFC falls within a predetermined range of expected valve control signals corresponding to the particular setpoint signal conveyed to the MFC;
and
a status interface for conveying information related to whether the actual valve control signal received from the MFC is determined to fall within the predetermined range.

2 more elements

Dependencies are inferred from the claim text.

Predictive failure monitoring system for a mass flow controller

Life of this patent

Predictive failure monitoring system for a mass flow controller

Life of this patent

Abstract

Claims26