GB901954A - Improvements in or relating to clothes dryers - Google Patents

Abstract

901,954. Tumbler driers. GENERAL MOTORS CORPORATION. May 10, 1961 [May 19, 1960], No. 16990/61. Class 34 (2). A clothes drier comprises an air blower, an air heater, a timer for controlling air flow past the clothes and heating of that air flow and a device responsive to relative humidity of air leaving the clothes arranged to stop the timer when the relative humidity is greater than a predetermined value. A tumbler drier drum 20, Fig. 1, has a perforated rear wall 22 for the passage therethrough of air heated by an electric heater 40 and circulated by a fan 36 in an exhaust duct 29 driven by the drier motor 38, and a humidity sensing element 46 in the duct is arranged to control a timer motor 66 by a solenoid 49, Fig. 3, and amplifier 50 through a switch 84. The timer 62 in normal operation controls the heater and a damper 34 in the duct 29 to provide high heat with high air flow, followed by low heat with low air flow, followed by high air flow without flow, but the element 46 stops the timer motor 46 when the relative humidity of the air leaving the drum is greater than a predetermined value. The control circuit for the drier comprises a thermoresponsive switch 54 placed near the heater 40 to de-energize the heater if the temperature in the casing exceeds 240‹ F.; a centrifugal switch 56 which is closed when the motor 38 is in operation, prevents energization of the heater if the motor fails to start, and a thermo-responsive switch 58 breaks the circuit if the amplifier 50 or element 46 fail or if the heater remains unenergized. The timer 62 comprises a shaft 64 controlled manually by a knob 76 for initiating the drying operation and carrying cams 68, 72 operating switches 70, 74 respectively, which move a series of contacts 82, 86, 88 and contact fixed contacts 78, 80 respectively. The fixed contacts 78, 80 are connected to side L 2 and neutral line N of the power supply respectively. The switch 70 is connected to side L 1 of the power supply and closes on the spring contact 82 which is connected by a lead 106 to the amplifier 50, by leads 107, 110 to the switch 84 controlling the timer motor 66 and by leads 107 to the drier motor 38. Further movement of the switch 70 causes the contact 82 to touch the contact 86 which is connected to the thermoresponsive switch 54 which in turn is connected to a switch 94 connected to one end of the heater 40 and the other end of the heater is connected to the thermo-responsive switch 58 movable between a contact 59 to the switch 74 and a contact 61 to the timer motor 66. Further movement of the switch 70 causes the contact 86 to touch the contact 88 which is connected through a solenoid 48 for controlling the damper 34 and so reduce air flow through the duct and drum.