GB1045131A - Gas burner ignition and control system - Google Patents

Abstract

1,045,131. Controlling gas burners. P. ROMANELLI, and A. ALFRED, [trading as RAM DOMESTIC PRODUCTS CO.]. Jan. 8, 1964 [Feb. 25, 1963], No. 863/64. Headings F4F and F4T. An ignition and control system for the gas burner 64 of a clothes dryer comprises a temperature responsive device heated initially by an ignition element and later by the burner and adapted to operate a primary switch 18 actuating an electromagnetic valve 60 controlling the flow of gas to the burner. The temperature responsive device may be either a tube containing mercury, the expansion of which is transmitted by a rod within the tube to a diaphragm at the end of the tube, Fig. 7 (not shown), or an expansible rod 30 rigidly held at one end 32 and loosely mounted in insulated blocks 36, 38. The free end of the rod 30 contacts a lever 26 pivoted at 28 and adapted to operate the primary switch 18 and a secondary switch 20 controlling the ignition circuit. The ignition element may be a resistance element, Fig. 6 (not shown), or a spark producing device comprising a vibrator 22 which vibrates a rod 42 to open and close a gap between the tip 48 of the vibrating rod and a contact 50 on the expansible rod 30. A pair of brush contacts 56, 58 make contact with the two rods. When the rod 42 is vibrated a spark is generated between the tip 45 and the contact 50 and heats the expansible rod 30 and serves to ignite the burner 64. In operation, when a thermostat in the dryer registers a low temperature it closes a circuit to energize the power lines L1, L2. A safety relay 24 is thus energized through the closed contact of the primary switch 18 and closes holding contacts 108 and contacts 110 which complete the circuit through the vibrator and the spark gap. The rod 30 is therefore heated and eventually actuates the primary switch 18 to energize the gas valve 60. The burner is thus ignited and causes further heating of the rod and consequential operation of the secondary switch 20, thus de-energizing the vibrator and the spark gap and also a resistance coil 134 heating an L-shaped bimetallic element 132 supporting the movable arm 129 of a lockout switch 120 so that the contacts thereof are closed. If the burner does not ignite the bimetal element eventually allows the movable arm to drop, thus de-energizing the igniter and the gas valve 60. The lock-out switch is reset automatically by a pivoted arm 140 biased by a spring 142 to swing in a clockwise direction and thus raise the movable arm 129 of the switch to close the contacts; but the arm 140 is prevented from doing so by the magnetic effect of the coil 104 of the safety relay 24. Resetting therefore can only take place when the safety relay 24 is de-energized by the removal of power from the power lines L1, L2. The safety relay immediately closes down the burner when the power supply fails and therefore prevents the gas valve re-opening at the end of a momentary power interruption. All the components are mounted on a T-shaped frame having at one end a curved U-shaped frame.