GB765942A - Improvements in or relating to gas burners and safety igniter circuits and controls therefor - Google Patents

Abstract

765,942. Controlling gas burners. WHIRLPOOL CORPORATION. Jan. 25, 1954, No. 22208/55. Divided out of 765,941 [Group XIII], Class 75(1) ' An ignition and safety control system for a gas burner, e.g. for supplying heated air to the drying drum of a household clothes dryer comprises an electrically operated master valve 135 in series with an electrically operated main valve 136 in the gas supply line to a main burner (not shown), a pilot burner 137 located beside the main burner and connected to the gas supply line between the two electrically operated valves and a flame detector switch 160 adapted to energize the electrically operated main valve 136 to open position in response to a flame at the pilot burner 137. At starting the coil 140 of the master valve 135 is energized to open the valve and supply gas to the pilot burner 137, through contacts 171, 172 of a time switch 170 comprising a warp element heated by a coil 184 disposed in a metal sheath 184b and energized through the cold contact 161 of the flame detector switch 160. 'The pilot burner is ignited by a glow coil 139 energized by a transformer 138 energized through the contacts 171, 172 of the time switch 170 and also through the cold contact 161 of the flame detector switch 160. If ignition is effected the movable arm of the flame detector switch 160 moves over to the hot contact 162 to de-energize the ignition transformer 138 and the heating coil 184 of the time switch 170 and to energize the coil 163 of the main valve 136 to open the valve. The main burner is then ignited by the pilot burner. If, however, ignition of the pilot burner fails the contacts 171, 172 of the time switch open after a predetermined time to close the master valve 135 and to deenergize the ignition transformer 138. An adjustable thermostat 173 in the circuit to the main valve 136 turns the main burner on and off during normal operation to control the temperature within the drying drum. A safety bi-metal switch 175 deenergizes the burner ignition and control system when the temperature of the drying drum is substantially higher than that at which the adjustable thermostat 173 opens. The drying drum is rotated by a motor 14 and the duration of each drying operation is determined by a timer motor 183 which opens first a switch 181 to deenergize the burner ignition and control system and later a switch 182 to de-energize the motor 14 rotating the drum and the time motor 183. A switch 61 operated by opening the door of the drier de-energizes the motor 14 rotating the drum, the timer motor 183 and 'the main valve 136 and energizes a lamp 131. In a modified system the master valve 135 is independent of the safety switch 175 and the switch 181 of the timer motor.