Patent GB-764682-A (GB)
Title: Improvements in control devices for gaseous fuel burners
Inventor: JACKSON WILBUR FRED
IPC: G05D23/02
Filed: 1953-05-12
Abstract: 764,682. Valves. ROBERTSHAW-FULTON CONTROLS CO. May 12, 1953, No. 13240/53. Class 135. A control device for gaseous fuel burners comprises a main valve 40, a movable electromagnet 74 having an armature 82 movable between an attracted position in which the main valve is free to open and a released position in which the armature positively closes the main valve, re-setting means such as the button 90, for moving the magnet into engagement with its armature 82, and means for opening an auxiliary valve 102 leading to a pilot burner during the re-setting operation and for holding the auxiliary valve open so long as the armature is in its attracted position, the auxiliary valve closing automatically when the armature moves to its released position. As applied to a water heater the valve 40 is arranged in a chamber 16 between a gas inlet 12 and a gas outlet 14 and is normally controlled by a thermal element such as the rod and tube 52, 54 acting on the valve through a thrust member 50 and a clicker disc to open the valve against a spring 67 abutting a sealing diaphragm 64 which separates the valve chamber 16 from the interior of a housing 62 for the magnet. The operative relation of the rod 52 and the tube 54 may be adjusted by a lever 60. The armature 82 has a stem 84 guided in the inner end of a cover 68 enclosing the magnet and adapted to move with it on depression of the push button 90. The armature is moved to its released position in which the free end of the stem 84 acts through the diaphragm 64 to hold the valve 40 closed by a spring 86 stronger than the spring 67. The button 90 and the cover 68 are biased outwardly by springs 92, 70 respectively. The auxiliary valve 102 is arranged in a chamber 28 separated from the interior of the housing 62 by a sealing diaphragm 110 and is opened against a spring 104 by a pin or strut 116 engaging the armature stem 84 and a plate 114 which acts on the auxiliary valve stem through the diaphragm 110. The pin 116 moves longitudinally with the cover 68 but is capable of a transverse movement relative to the armature stem 84 in a bearing 118. The armature stem 84 has a reduced portion 120 and a portion 122 of wider diameter separated by a frusto-conical portion 124. As the cover 68 is moved inwardly the pin 116 rides up on to the portion 122 so as to open the auxiliary valve 102. The coils of the magnet are connected to a source of electrical energy such as a thermocouple arranged to be heated by the pilot burner flame so that if this flame is burning the armature and the magnet remain in engagement when the button 90 is released and the parts occupy the position shown in Fig. 2 with the auxiliary valve open. If the pilot flame should become extinguished, the stem 84 moves to the right in Fig. 2, and the pin 116 re-engages the reduced portion 120 so that valve 102 closes. A stop cock 18 controls the gas supply to the chamber 16 and also the supply through a pilot passage 24 and a filter 29 to the auxiliary valve chamber 28. In a modification, the auxiliary valve is actuated by a lever pivoted to a part on the armature stem and having an offset portion engaged by a boss on the magnet cover 68. In a further modification, the auxiliary valve is opened by a lever pivoted in the housing 62 and having an offset portion engaged by the inner end of the cover 68. A disc on the armature stem 84 holds the lever in the valve open position until the armature is released.