GB901475A - Improvements in dish-washing machines - Google Patents

Abstract

901,475. Control of motors. BULPITT & SONS Ltd. Oct. 31, 1958 [July 31, 1957], No. 24231/57. Class 38 (3). [Also in Groups XXIII and XXXV] A dish-washing machine comprises an electrically-heated storage tank for receiving a quantity of water for the washing or rinsing stage in the operating cycle of the machine, and means for limiting the temperature to which the water in the storage tank is heated and thermally actuated means for initiating a device controlling the succeeding stages in the operating cycle when the water in the storage tank reaches a predetermined temperature. As shown, water is heated in tank 12 and when it reaches a desired temperature as a result of heating by immersion heater 17, a thermallycontrolled change-over switch 42 is actuated to turn off the heater and at the same time to start timer clock 47 and also to allow fresh water to flow into tank 12 at a predetermined rate governed by a variable area orifice device for a predetermined time governed by timer 47. The fresh water displaces the heated water through hose 15 into the washing chamber where it is circulated by pump 28 through sprays 30. Crockery rack 32 is supported at the front by rollers resting in brackets 35, near the hinges of door 31, which serve to pull the tray forward slightly when the door is opened. Used water is drained from the machine by the energization of a solenoid which pulls down an arm against the supporting tension of springs 36 lowering flexible drain hose 25 so that water flows out of the machine. Fig. 4 shows the supply terminal 40 connected to heating resistor 41 of immersion heater 17 and via thermally operated switch 42 and contact 50 of relay 45 back to terminal L. While loading the crockery racks, push-button switch 48 may be depressed to complete a circuit through door-operated microswitch 44 which is in the position shown when the door is open, through coil 52 of relay 45, through contact 56 of camshaft timing device 46 back to terminal N. The energization of coil 52 actuates contacts 50, 51 and 58 of relay 45 bringing heater resistor 41 into the circuit, completing the holding circuit, through coil 52 via contact 51, and energizing warning light 49. The closure of the door actuates microswitches 43 and 44 but timer motor 47 does not start until the temperature of the water causes the actuation of change-over switch 42. The process is then controlled by timing device 46, motor 47 being kept in motion by current supplied over contacts 57 when the change-over switch returns to its original position upon the introduction of a fresh charge of cold water in the tank 12. Specification 901,476 is referred to.