Fluid flow control system - uses time modulation control of pump or valve, esp. for burner of central heating installation

摘要

Conventional fuel systems and other processes using fluid controls such as needle valves and float valves suffer from the fact that the flow of fluid for one setting of the valve can vary with changes in temperature, viscosity, etc. This system uses a detector (2) which measures the actual effect of the fuel or other fluid on the process (1), and switches the supply of fluid on and off periodically. The detector signal is compared (3) with a reference (4) set by the operator, and the comparator output controls a timing system (5). The timing system controls the lengths of time for which the valve is fully open or closed. This control process is analogous to pulse-width modulation in the electronic field.