GB562592A - - Google Patents

Abstract

562,592. Fluid pressure servomotors and control systems. BRASSERT & CO., Ltd., H. A., and NISSIM, R. Dec. 18, 1942, No. 18022. Addition to 554,070. [Class 135] A mechanical movement varying with a, physical value acts through a system of levers of variable mechanical advantage to control the escape valve of the regulator claimed in the parent Specification. In the arrangement shown in Fig. 1, the needle valve 31 of the main regulator 32 is actuated by a diaphragm 30 subject to the pressures in chambers 25, 26 which are supplied with compressed air by a fan 22 through connections 23, 24, the connection 24 being provided with a shut-off cock 29. Air is vented from the chambers 25, 26 through pipes 27, 28 leading to nozzles 19 controlled by needle valves 17, 18. The valve 17. is carried by a lever 11 pivoted at 12 and subject to the controlling impulse at 10. The lever 11 acts through a ball 15 on an adjustable flexible arm 16 on a lever 13 pivoted at 14, adjustably loaded by a spring 21 and carrying the valve 18. In the arrangement shown in Fig. 2, a second diaphragm 44 subject to the pressures in the chambers 25. 26 reacts on the lever 13 to provide a follow-up action. In this form, the lever 11 is operated by a face cam on a rotary controlling shaft 37. In a modification of this form, the lever 11 is actuated by a centrifugal governor. In the form shown in Fig. 4, a centrifugal governor acts through the adjustable lever mechanism on the needle 47 of the main regulator and the follow-up action is obtained through a Bourdon tube 49 subject to the pressure in the control chamber. In another form controlling the supply of air to a furnace, both needles are carried by one of the levers and are actuated by a pair of diaphragms interconnected by the adjustable lever mechanism and subject to the pressure differentials across surface plates in two conduits supplying furnace with blast furnace gas and coke oven gas. In still another form a single pair of needle valve controls two main regulators, one of which is also under the control of a second controlling impulse.