Temperature compensated pneumatic control system

Claim 1

In a pneumatic control system, the system including a source of operating gas and electrically actuated flow control valve means for regulating the delivery of gas from the source to a load, means providing compensation for the effects of variation in temperature on the system comprising: means responsive to input signals commensurate with the actual and desired positions of a pneumatically operated load on the system for generating a position error signal; temperature sensitive means, said temperature sensitive means providing an output having electrical characteristics which vary with temperature; oscillator means for generating an alternating signal; amplifier means; means for applying the signal provided by said oscillator means to said amplifier means; means connecting said temperature sensitive means in a feedback circuit for said amplifier means whereby the amplitude of the output signal provided by said oscillator means is varied in accordance with the electrical characteristics of the output of said temperature sensitive means; switch means responsive to said position error signal and to said amplitude variable oscillator output signal for providing output signals having a duration and polarity commensurate with the position error compensated for variation from a preselected temperature; and means for applying the output signals provided by said switch means to said electrically actuated flow control valve means.