INCREMENTAL CONTROL OF A VALVE-ACTUATOR EMPLOYING OPTOPNEUMATIC CONVERSION

A demonstrator has been built in which a pipe valve can be opened and closed incrementally by direct optopneumatic control of the 3 to 15 lbf/in2 actuator. The optical energy is provided by inexpensive laser-diodes. The infrared fight is conveyed by optical fibres to miniature convertor cells, where it is converted into pressure changes that can be amplified by standard pneumatic components to control the pipe valve actuator in order to open or close the valve. The pipe valve can be set with a positional accuracy of about 1 % of the full range. The time response for each incremental change of 1 lbf/in2 is of the order of a second. © 1990.