GB926671A - Improvements in automatically controlled electric kettle - Google Patents

Abstract

926,671. Thermal switches. CANADIAN GENERAL ELECTRIC CO. Ltd. April 5, 1960 [April 7, 1959], No. 11992/60. Class 38 (5). [Also in Group XI] A thermostatic switch of an electric kettle (see Group XI) has a bi-metal strip directly exposed to the steam in the water chamber of the kettle, whereby the switch contacts, which are resiliently biased towards one another are opened at a desired temperature. The base 32 of the switch is mounted in an enclosed space, formed by the roof of the water chamber and the chamfered base of the handle, by bolts 42a and 42, the latter having a second shank 46 projecting into the water chamber to support bi-metal strip 32 therein. The switch contacts 30 and 31 are mounted on, and biased towards one another by, resilient arms 38 and 40, the upward displacement of arm 38 being limited by abutment against pin 39, axial adjustment of which is procured by rotation of knob 15 secured to the top of screw 37. Rise in temperature in the water chamber opens contacts 30, 31, at a temperature determined by the setting of pin 39, due to the thrust exerted by bi-metal strip 32 through the silicone rubber resilient membrane 33. A modified switch, Figs. 3 and 4, has a snap action, provided by spring member 67 on which the movable contact 68 is mounted, connection to the latter, and to stationary contact 76, being made via terminals 74 and 84 respectively. Member 67 has an aperture 95 for the receipt of bolt 71, an aperture 101 with its rim formed into a spiral for the receipt of, and engagement with, adjusting screw 66, two slots 96 and 97, and a crimp 102 shortening the length of portion 98, whereby member 67 has two stable flexed positions. The strips 99 and 100 are clamped, over their portions furthest from contact 68, between U-shaped members 103 and 104. Adjusting screw 66 has a ceramic portion 91, with which it is rotationally engaged, in a manner permitting relative axial movement, by tongue and slot 92, 93. The thrust of the bi-metal member 78 through the resilient membrane 94 snaps the switch off at a desired temperature determined by an initial adjustment of the screw 66.