GB1340853A - Liquid heating units control means for such units and vessels incorporating heating units - Google Patents

Abstract

1340853 Magnetic switches HOOVER Ltd 7 Jan 1971 [9 Jan 1970 27 July 1970 30 Oct 1970] 1254/70 36345/70 and 51833/70 Heading H1N An immersion heating unit for an automatic beverage maker or electric kettle includes a Curie effect switch interrupting the supply to the heater when the appliance boils water or boils dry, a manual reset being provided for reclosing the switch contacts. At the Curie temperature, a pivoted magnet 35, Fig. 2, drops from its position engaging the section 37 of a nickel-iron alloy ferromagnetic element 38 and attracts an armature 48 to separate the contacts 25. Such movement of the magnet 35 also moves rod 50 and, via lever 52, releases a plate 18 to disperse tea into the boiling water in the receptacle 10, steam from which is conveyed via a tube 44 to the element 38 to heat it. For resetting, the lid 15 is removed and rod 50 depressed. In a kettle, the rod acting on the magnet 35 can be merely for resetting, Figs. 3, 4 (not shown). The control mechanism may utilize a magnet 99, Fig. 5, moving rectilinearly from part 100 of a ferromagnetic element 101 to open contacts 84, 85, by engaging a pin 91 through a diaphragm 90. An S-shaped lifter member 115 restores the magnet 99 when required. A neon lamp 138 indicates when the contacts 84, 85, are closed. If it is desired to bring water back to the boil before the main ferromagnetic element 160, Fig. 9, has cooled sufficiently, a second ferromagnetic element 183 may be employed which attracts the magnet 156 sufficiently to allow the switch contacts 162, 163 to close, even though element 160 is not cool enough to attract the magnet 156. Element 183 is mounted on the reset lever 180 which has a cam 186 co-operating with a projection 188 on the magnet 156. Two levers 180 with elements 183 may be provided. Another way of providing two or more ferromagnetic elements 250, 251, Fig. 13, either or any of which may co-operate with the magnet 242 and be in heat conductive contact with the heater 265, is to mount the elements 250, 251, on a manually rotatable sleeve 247 indexable in the required positions. A lifter member 270 is provided for resetting. Ferrites 250, 251, may have different Curie points and the appliance may be a deep fat fryer.