THERMAL MASS FLOWMETER AND CONTROLLER

摘要

A mass flowmeter and controller measures the mass flow rate of liquid or gaseous fluids and controls the flow rate of the fluids being utilized in a processing operation. A series of flow channels and blocked channels are micro-etched from a silicon substrate leaving an integral membrane suspended across the channels. A heater-sensor thin film resistor, diode or transistor is formed on the membranes and the substrate during manufacture to sense the temperature at particular locations. A cover housing matching channels and grooves forms flow and stagnant blocked conduits in the structure. Through a bridge circuit a signal indicative of mass flow is produced. This signal is passed to a control valve armature coil in an in-line flow control valve. The controller includes a sensor module containing monitored flow and blocked channels and passive by-pass channels as required for additional flow capacity, a control valve cartridge, an overall housing and the magnetic armature coil which controls the flow of fluid through the valve and the sensor module.