GB761268A - Electrically heated coffee percolator - Google Patents

Abstract

761,268. Thermal switches. SUNBEAM CORPORATION. March 19, 1954, No. 8151/54 Class 38(5) [Also in Groups XI and XIII] A coffee maker has a vessel containing water to be heated by a single coiled sheathed electric heater 26 at its base controlled by a bimetallic strip 54 attached at one end to an L-shaped copper lug 58 soldered on the base of the vessel. A heatstorage metal block 65 is attached to the bimetal strip so as to delay the operation of the bimetal strip in response to the initial heating of the liquid on the initial heating of the vessel, until the temperature of the vessel is higher than that for which the switch is set, during which time percolation of ot water from the pump through the tube 31 over the coffee in a container at the head thereof takes place. When the bimetal 56 opens the switch at the higher temperature e.g. 200‹F., the liquid cools to the preset temperature e.g. 160‹F. of the switch, whicht hen maintains the coffee at that lower temperature. A leaf spring 57 also mounted on the lug 58 carries a contact 56 engaging a contact 55 on the bimetal strip 54 through which the heating current for the vessel passes, the leaf spring and the bimetal strip being insulated by washers from the lug 58 and the metal block 65. The sheathed heater 26 is coiled round a metal block 22 recessed at the top 22a to form a pump or steam generating chamber 25 in the vessel 11 and is surrounded by an annular shield 68 attached to the base of the vessel to protect the bimetal strip from direct radiation from the heating element 26. A disc 75 closing the base of the shield 68 is attached to the base 18 of the percolator by a central screwed stud and by two adjacent supports. The disc 75 has a lateral extension 83 carrying contact pins 86 for connection to an exterior supply cable. One pin 86 is connected to the bimetal strip 54. The other pin is connected through an indicating lamp 95 and a voltage drop resistor 94 in parallel therewith to one end of the heating element 26, the other end of the element 26 being connected to the leaf spring 57. In order to control the strength of the coffee, a manually rotatable hollow knob 103 carries an internally and externally threaded control rod sleeve 107 engaging externally an internally threaded nut 109 fixed on a bracket 110 so that on rotation of the knob the sleeve 107 slides in a hexagonal recess 105 in an extension 103a of the knob. A control rod 112 threaded within the sleeve 107 has an extension 113 bearing on the switch leaf 57 and is adjustable by access through the knob 103 to adjjust the initial distance of the contact 56 thereon from the contact 55 on the bimetal strip. The dial of the knob is translucent so that light from the lamp 95 is visible when the heater is energized. The knob 103 has an escutcheon member 116 fastened at 117 to the bottom cover 18 and has a pin 120 engaging an arcuate groove 119 in the member 116 to limit the rotary movement of the knob. A removable leaf spring 125 inserted in a recess 126 between the bottom cover 18 and the knob 103 retains the latter in position and rends it readily removable,