Improvements in control devices

摘要

931,749. Electric analogue computers. RHEOSTATIC CO. Ltd. Feb. 13, 1961 [March 15, 1960], No. 9117/60. Class 37. [Also in Group XXXVIII] Means providing an electric signal dependent upon the product of a function of the speed of wind and the approximate difference between the wind temperature and a first preset temperature comprises a bridge circuit 8 including a first temperature-sensitive element 13 enclosed in thermally insulating material and a second temperature-sensitive element 14, the insulating material being exposed to wind and element 14 being exposed to wind at a reduced velocity. The elements are heated equally to approximately the first preset temperature when the wind speed is zero by a resistive heater 15, 16 energized in dependence upon the difference between the wind temperature and a second preset temperature, and bridge circuit 8 is energized by a preset voltage and is arranged to balance when the first and second temperaturesensitive elements are at the first preset temperature. In a modification the heater is energized by the preset voltage, but is not maintained at a constant temperature, and the bridge circuit is energized by the wind temperaturedependent signals. The circuit forms part of a control system controlling the temperature in an enclosed space heated by a heating fluid (see Group XXXVIII). Specification 871,562 is referred to.