Patent GB-1079476-A (GB)
Title: Improvements in or relating to space lighting fittings
IPC: F23N5/08
Filed: 1966-03-17
Abstract: 1,079,476. Controlling burners. M. E. LIESSE. March 17, 1966, No. 11796/66. Headings F4F and F4T. A space lighting fitting comprises burners 1-4 grouped in a fixture 5 and supplied with gas via an electromagnetic valve 8 through pipe 6, each burner having associated with it an ignition spark electrode, e.g. 13, supplied from a multivibrator 31 which is only energized when photo-resistive cells 15 detect an absence of flams at the burners, the whole fitting being controlled by a switch 51 which energizes the multivibrator and actuates valve 8. When switch 51 is closed voltage from a source 50 is applied to feed wire 18 causing the valve 8 to open. A control amplifier 60 receiving signals through wire 19 causes relay 42 to maintain contact 41 closed, this supplying current to the multivibrator, until the flames are established. The wire 19 is connected by diodes 27 to the terminal 25 of each cell 15 and each terminal 25 is connected to the feed wire 18 by a constant resistance 26, and to earth a line 20 by cell 15. When a cell is illuminated by a flame the potential of the corresponding point 25 is brought close to earth potential; when all the flames are alight, the cathode of each diode 27 is brought close to earth potential and the diodes are blocked, no current flowing into the base of detecting transistor 61 of amplifier 60 and relay 42 relaxes interrupting the supply to multivibrator 31. If a flame is extinguished the value of the corresponding cell 15 is restored to a high level and the potential of terminal 25 comes close to the potential of feed wire 18, being a negative potential in this instance. Beyond a certain threshold, which is established by the position of sliding contact 65 of a threshold control potentiometer 66, the corresponding diode 27 becomes .conductive at the same time as the diode represented by the emitter and the base of transistor 61, the current thus engendered, amplified by 60, causing the reconnection of relay 42 to occur. The burner tube 11, associated cell 15, electrode 13 with a series resistance 14 are embedded in a translucent plastics material 10. The multivibrator 31 comprises transistors 32, 33 having a step-up transformer 34, the transformer having a primary winding 35 whose centre tapping is supplied from contact 41 through a wire 36, a winding 37 whose centre tapping is raised to a definite polarizing potential by a resistance bridge 38, 39 set up between wire 36 and earth 20, and a secondary winding 40 with a centre tapping to earth and extreme terminals connected to wires 16, 17 supplying the spark electrodes. The source 50 is formed by a rectifying bridge 54 supplied from A.C. grid 55 through step-down transformer 56, or in the event of mains failure by a battery 53 Safety switches 57, 58 and a thermal contact-breaker 52 are provided. The cells 15 may be replaced by thermocouples or thermoresistors, or the ionization caused by the flame heat may be used to detect the flame. Electric lighting may be combined with the fitting and in the event of cyclic neon lighting the sensitivity of the flame detection circuit reduced by a timelag element formed by a condenser 73 and a resistance 74.