GB470401A - Improvements in means for controlling automatically a variable condition - Google Patents

Abstract

470,401. Automatic control systems. KENT, Ltd., G., IVANOFF, A., and HOWARD, G. P. E. Feb. 10, 1936, No. 4035. [Class 38 (iv)] Temperature &c. -A valve 5 is actuated in order to control a variable condition such as the temperature of a furnace 2, by a reversible electric motor and a contact 9, on an arm 8 co-operating with two contacts 11, 12, on an arm 13. The arm 8 is positioned in accordance with the state of the variable condition, such as the furnace temperature by means of a connection from a device 1 responsive to the condition. The arm 13 is moved by two devices to which it is differentially connected, one of which is moved in accordance with changes in the setting of the valve 5 and the other at a speed depending on the extent of departure of the variable condition from the desired value. The first movement is produced by a Selsyn connection 16, 18, from the valve or its motor 15 to a cam 20, actuating an arm 21 coupled to one end of a link 24. The second movement is produced as follows. The arm 8 carries a pin (not shown), lying between two spring- controlled arms 36, 37, which close upon it, while a cam 32 is permitting a spring brake to hold it ; the arms are opened at regular intervals by a cam 38. A three armed rocker 40, has a pin 39 lying between these arms so that when they close its position is determined by the position of the other pin. The rocker arms 41, 42 have upturned ends containing rollers adapted to clutch them to a disc 44 on their upward movement. The speed of movement of the disc 44 and its direction thus depends on the extent and sense of the departure of the variable condition from the desired value. The motion of the disc is communicated through gears and a link 25 to the other end of link 24, and the arm 13 is connected to an intermediate point in this link.