An automatic control system

摘要

867,217. Automatic control systems. ZAVODY RUDYCH LETRIC 1930, NARODNI PODNIK. Nov. 12, 1958 [Nov. 21, 1957], No. 36367/58. Class 38 (4). A switch operated by change of a measured variable controls, through a delayed-action electric relay, the energization of an electric element heating fluid in an enclosed chamber to operate a regulator by the change in pressure of the fluid. In Fig. 2 when a variable, e.g. temperature or humidity in an air-conditioning system, falls below a predetermined value, contacts 80 close to energize a relay 50 from an A.C. source through a germanium diode 40 so that contacts A1, C1 open to de-energize a heater 1 associated with a two-fluid vapour generator 9, the inner wall of which is in the form of a bellows so that a valve 4 is opened to restore the variable to the predetermined value e.g. by increasing a heat supply. To reduce sparking, a germanium diode 70 is connected to provide a circuit for currents self-induced in relay 50 when contacts 80 open. A resistance-condenser network 30, 60 may also be provided to delay operation of relay 50 so that it does not follow high-frequency operation of contacts 80 caused, for example, by vibration of a body on which the contacts are mounted.