GB559813A - Improvements in the automatic control of a variable condition - Google Patents

Abstract

559,813. Automatic control systems for variable conditions. NEGRETTI, H. N., NEGRETTI, P. E., and IBBOTT, H. W. July 1, 1942, No. 9108. [Class 38 (iv)] Variables in general ; temperature.-A primary device 1 responsive to changes in a controlled condition exerts a force against a resistance, shown as springs 10, 11, through a mechanical linkage comprising a pivoted lever 9, rod 8, pivoted frame 6, rod 4 and pivoted frame 2. Movement of the frame 6 due to unbalance operates the contact 12 of a reversing switch for a motor 15 to correct a change in the condition. One or more secondary devices 16, 17 are adapted to alter the leverage of the linkage in accordance with changes in conditions to which they are responsive and which require to be taken into consideration in the control. These devices are connected to the linkage through bell crank levers 3, 5, 7 pivoted on axes inclined to the axes of the frames 2, 6 so that they do not react with the force transmitted through the linkage. A cam 25 may be adapted to remove the pressure of spring 10 and a cam 17 may be arranged to vary one pressure or both. These cams may be actuated automatically or at will. The arrangement is suited for the regulation of the temperature of aircraft engines, the primary device being subject to the differential pressure set up by the passage of cooling air, other variable factors such as boost pressure cooling in temperature, altitude, supercharger gear, and pilots' will being imposed upon the control.