GB261407A - Improvements in or relating to thermal control devices - Google Patents

Abstract

261,407. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Gano, H. S.). Nov. 14, 1925, [Convention date]. Thermal switches. - A device for regulating the temperature of water, &c. comprises a main bimetallic element or coil 30 which when cooled or heated by the water rotates a shaft 31 and causes a contact 41 to engage either a contact 82 or a contact 79, thereby closing a, circuit to an electromagnet 85 or 95 and moving a reversing switch 87 into one or other of its end positions in which a circuit is closed to a motor 88 which then rotates a shaft so as to open or close a valve 89 allowing or preventing the entrance of steam into the water. The coils 85, 95 of the reversing switch are in series respectively with two auxiliary bimetallic elements or pairs of elements 54, 53 which, when heated, tend to rotate the shaft 31, but in opposite directions. Assuming that the water is below the required temperature and that the parts are in the position shown, a circuit is completed from the lead L1 through the bimetallic coil 54, electromagnet 85, contacts 82, 41 to lead L2. The reversing switch 87 is actuated and the valve 89 is opened by the motor 88 allowing steam to enter and heat the water. The coil 54 is heated by the current passing through it, and causes the contact 41 to move from the contact 82 thus breaking the circuit through the thermal coil 54 and the electromagnet 85 and stopping the motor. The coil 54 now cools down and will again cause the contact 41 to engage the contact 82 and the valve 89 to be opened still wider bv the motor 88 unless by this time the main thermal coil 30 has reached a temperature sufficient to hold the contacts 41 and 82 apart. Assuming the latter to be the case, the temperature of the water will continue to rise through the steam entering it until the main thermal coil 30 causes the contact 41 to engage the contact, thereby actuating the reversing switch 87 causing the motor to close, the valve 89. The auxiliary coil 53 now comes into action and acts similarly to separate the contacts 41, 79 and stop the motor before the main coil 30, acting alone, would have done so. The contacts 79 and 82 are constituted bv the cores of electromagnets in series with the coils 95, 85 respectively to give a quick action to the contact 41. The end of the coil 30 not connected to the shaft is adapted to be adjustably rotated for temperature setting.