On-off and modulating condition control valve

Claim 1

A CONDITION RESPONSIVE PILOT VALVE FOR CONTROLLING THE PRESSURE IN THE OPERATING PRESSURE CHAMBER OF A MAIN VALVE, THE PILOT VALVE COMPRISING: A TWO-POSITION CONTROL VALVE; FIRST PASSAGE MEANS ADAPTED TO CONNECT SAID CONTROL VALVE TO THE INLET, THE OUTLET, AND THE PRESSURE CHAMBER OF THE MAIN VALVE SO THAT IN ONE OF ITS POSITIONS SAID CONTROL VALVE CONNECTS THE PRESSURE CHAMBER TO THE INLET AND, IN THE OTHER OF ITS POSITIONS, SAID CONTROL VALVE CONNECTS THE CHAMBER TO THE OUTLET; SECOND PASSAGE MEANS ADAPTED TO CONNECT THE CHAMBER TO THE OUTLET OF THE MAIN VALVE; MODULATING VALVE MEANS IN SAID SECOND PASSAGE MEANS AND INCLUDING PRESSURE RESPONSIVE OPERATING MEANS ADAPTED TO BE CONNECTED SO THAT IT IS OPERABLE BY PRESSURE AT THE OUTLET OF THE MAIN VALVE TO POSITION SAID MODULATING VALVE MEANS TO CONTROL THE PRESSURE IN THE CHAMBER TO MAINTAIN A SUBSTANTIALLY UNIFORM PRESSURE AT THE OUTLET; LOADING MEANS OPERABLY ASSOCIATED WITH SAID OPERATING MEANS AND VARIABLE BETWEEN MINIMUM AND MAXIMUM LOADING CONDITIONS TO VARY THE PRESSURE AT WHICH SAID OPERATING MEANS OPERATES; A CONDITION RESPONSIVE OPERATOR INCLUDING SENSING MEANS AND AN OUTPUT MEMBER MOVABLE IN RESPONSE TO VARIATIONS OF THE CONDITION BEING SENSED; SNAP-ACTING MEANS OPERABLY CONNECTED TO SAID TWO-POSITION VALVE AND NORMALLY MAINTAINING SAID TWO-POSITION VALVE IN ONE OF ITS POSITIONS; YIELDABLE MEANS NORMALLY MAINTAINING SAID LOADING MEANS IN A FIRST OF ITS POSITIONS; A FIRST LEVER PIVOTED ON SAID HOUSING AND HAVING ONE END OPERABLY CONNECTED TO SAID SNAP-ACTING MEANS; A SECOND LEVER PIVOTALLY CONNECTED TO THE OTHER END OF SAID FIRST LEVER AND OPERABLY CONNECTED AT ONE OF ITS ENDS TO SAID OUTPUT MEMBER; A THIRD LEVER PIVOTALLY CONNECTED TO THE OTHER END OF SAID SECOND LEVER AND HAVING ONE END PIVOTED ON SAID BODY AND THE OTHER END OPERABLY CONNECTED TO SAID LOADING MEANS, THE RESILIENCE OF SAID SNAP-ACTING MEANS AND OF SAID YIELDABLE MEANS AND THE EFFECTIVE LENGTHS OF SAID LEVERS BEING CHOSEN SO THAT UPON INITIAL MOVEMENT OF SAID OUTPUT MEMBER IN ONE DIRECTION SAID THIRD LEVER REMAINS SUBSTANTIALLY STATIONARY AND SAID SECOND LEVER PIVOTS WITH RESPECT THERETO AND PIVOTS SAID FIRST LEVER WITH RESPECT TO SAID BODY UNTIL SAID SNAP-ACTING MEANS IS SNAPPED OVER-CENTER AND OPERATES SAID TWO-POSITION VALVE TO THE OTHER OF ITS POSITIONS AND SO THAT UPON FURTHER MOVEMENT OF SAID OUTPUT MEMBER IN THE SAME DIRECTION, SAID FIRST LEVER REMAINS SUBSTANTIALLY STATIONARY AND SAID SECOND LEVER PIVOTS WITH RESPECT THERETO AND PIVOTS SAID THIRD LEVER TO VARY THE LOADING ON SAID OPERATOR FOR SAID MODULATING VALVE.