Electronically controlled flow meter and flow control system

Abstract

A novel, low-friction, low-inertia flexible diaphragm containing a magnet formed as an integral part of the diaphragm is mounted in a chamber (preferably cylindrical). The chamber comprises part of the flow meter in a flow control system. One or more sensing devices are mounted on the walls of the chamber to sense the instantaneous position of the diaphragm. A novel electronic control circuit processes the data from the one or more sensing devices to provide measures of the flow rate during the displacement of the diaphragm along the cylinder. Signals are generated by the electronic control circuitry for switching a pair of three-way valves (one valve comprising the input valve and the other valve comprising the output valve) such that during one-half of a cycle the intput valve transfers fluid into the cylinder on one side of the diaphragm and, during the other half of the cycle, transfers fluid into the cylinder on the other side of the diaphragm. The output valve is switched synchronously with the input valve to transmit fluid from the other side or one side of the diaphragm to the output valve. The electronic control system includes means for amplifying the output signals from the one or more sensing devices ('sensors') to provide one or more signals representing the position of the diaphragm as a function of time, means for converting the output signals from these amplifiers to digital form, and computation means for operating on the digitized output signals from the sensing devices to provide control signals for controlling a second input valve thereby to control the flow rate of the fluid being metered to within a desired range.