Digital blend system

Claim 1

A DIGITAL TRIM SYSTEM COMPRISING: AN ANALYZER MONITORING THE CONCENTRATION OF A SELECTED TRIM COMPONENT OF A MAIN STREAM, CONVERTING MEANS RESPONSIVE TO THE OUTPUT OF SAID ANALYZER FOR CONVERTING SAID OUTPUT TO A PULSE DURATION SIGNAL SIGNIFYING THE TRIM COMPONENT CONCENTRATION DETERMINED BY SAID ANALYZER, A FLOW METER RESPONSIVE TO THE FLOW OF A TRIM STREAM SUPPLYING SAID MAIN STREAM HAVING AN OUTPUT CONSISTING OF A PULSE TRAIN SIGNIFYING THE FLOW OF SAID TRIM STREAM, A SCALER HAVING AN INPUT RESPONSIVE TO SAID PULSE TRAIN OUTPUT OF SAID FLOW METER AND HAVING TWO SCALED OUTPUT PULSE TRAINS EACH HAVING A PRESELECTED PROPORTIONAL RELATIONSHIP TO SAID PULSE TRAIN OUTPUT OF SAID FLOW METER, SWITCHING MEANS RESPONSIVE TO SAID PULSE DURATION SIGNAL FROM SAID CONVERTING MEANS AND ACTUATED BY SAID PULSE DURATION SIGNAL AND HAVING TWO INPUT TERMINALS EACH RESPECTIVELY RESPONSIVE TO ONE OF SAID TWO SCALED OUTPUT PULSE TRAIN FROM SAID SCALER AND SAID TWO INPUT TERMINALS BEING ALTERNATELY SELECTED BY ACTUATION DETERMINED BY SAID PULSE DURATION SIGNAL AND HAVING AN OUTPUT TERMINAL WHEREBY ONE OF SAID TWO SCALED OUTPUT PULSE TRAINS IS CONNECTED TO SAID OUTPUT TERMINAL OF SAID SWITCHING MEANS, A REFERENCE OSCILLATOR, A PULSE DIFFERENCER HAVING A FIRST INPUT RESPONSIVE TO THE OUTPUT OF SAID OSCILLATOR AND HAVING A SECOND INPUT RESPONSIVE TO THE SELECTED SAID SCALED OUTPUT TRAIN AT SAID OUTPUT TERMINAL OF SAID SWITCHING MEANS AND HAVING AN OUTPUT CONSISTING OF THE PULSE DIFFERENCE BETWEEN SAID FIRST AND SECOND INPUTS, MEANS FOR CONTROLLING A VALVE RESPONSIVE TO SAID OUTPUT OF SAID PULSE DIFFERENCER, A VALVE REGULATING SAID TRIM STREAM RESPONSIVE TO SAID MEANS FOR CONTROLLING A VALVE.