GB1352233A - Electrically controlled gas valve - Google Patents

Abstract

1352233 Partly electromagnetic switches MACLAREN CONTROLS Ltd 23 Dec 1971 [8 Sept 1971] 41829/71 Heading H1N [Also in Division F2] An electrically controlled gas valve comprises a closure member 1, Fig. 1, connected to armature 12 of electromagnet 13 via a pair of lever arms 3, 5 pivotally mounted at 4. The arms are in the form of bimetallic strips. When the arrangement shown is energized the bimetallic arm 5 is heated by heater 8 and thereby bends to move armature 12 towards the energized electromagnet 13 until it is magnetically attracted to it and held. Thus the switch 9 opens and the subsequent cooling and straightening of arm 5 causes the closure member to be lifted off its seat 2. If desired the bimetallic arm 3 may be associated with a separately energizable heater to adjust the degree of opening of the valve 1, 2. The arms 3, 5 may be extended and support contacts of further switches. Another arrangement has a pilot gas valve carried by an extension of arm 5 so as to open when the arm 5 is heated. This enables a pilot burner to ignite and thereby heat a thermocouple to generate electricity which is used to energize the electromagnet to cause subsequent opening of the main valve 1, 2 which then remains open as long as the pilot burner is alight. To avoid the pilot valve remaining open when ignition at the pilot burner has not occurred, a device breaks the circuit to the heater for a predetermined time. In another embodiment, Fig. 2 (not shown), the arms between the armature and closure memare not bimetallic and the electromagnet is mounted on one end of a lever (17), and is moved towards the armature when a wire (21) attached to the lever at the other side of the pivot, is heated. The wire may be replaced by a rod or a wax element.