Patent GB-671274-A (GB)
Title: Improvements relating to dish-washing machines
IPC: D06F35/00
Filed: 1950-05-04
Abstract: 671,274. Dishwashing machines. CARLSTEDT, S. B. F. May 4, 1950 [May 4, 1949], No. 11100/50. Class 138 (i). Relates to a dishwashing machine of the type having an upper part receiving articles to be washed, a lower part communicating with the upper part, a liquid supply conduit, and an electric motor driven shaft in the lower part and carrying at least one impeller member for throwing liquid from the lower part against the articles, wherein liquid is supplied continuously to the machine only when and so long as the impeller is in operation. As shown in Fig. 1 the machine comprises an upper part 30 for the dishes and a lower part 10 in which is mounted a horizontal shaft which has disposed along its length three counterbalanced paddles, side by side but displaced relative to one another circumferentially by 120 degrees. The shaft is driven by a pulley 14 from a series type electric motor 18. Secured to one end wall of the lower part 10 by a flange 38 is a chamber 36 to which is secured a valve chamber 40. The valve body 46, Fig. 3, is hexagonal in cross section and displaceably located in a circular bore 48 in the chamber 40. The valve 46, which includes a rod 52 passing through the chamber 36 and projecting upwardly a short distance therefrom is normally engaged against a seating, formed by a packing 44 interposed between the chambers 36 and 40, by a spring 50. A hot water supply conduit is connected to the chamber 40 at 66 and the chamber 36 connects at 80 with a conduit 82, Fig. 1, which communicates with upper part 30 through a protective device 84 which prevents back suction of liquid already in the machine should a vacuum be formed in the conduit 82. Pivoted to the flange 36 at 56, and above the rod 52 is a mercury switch 54 which according as to its angular position closes or opens the circuit of the motor 18. The switch 54 is operable by a rod 60 provided at its upper end with a button or similar member 62. The lower end of the rod 60 enters an angular recess 64 in the switch. The button 62 may be retained in the pressed-down position shown in Fig. 1 by any suitable means e.g. a ratchet device which becomes operative after a quarter of a revolution. In operation the button 62 is depressed so that the motor 18 is started and the impeller members are rotated within the lower part 10. At the same time the switch 54 depresses the valve body 46 so that hot water passing a restriction 70, throttled adjustably by the conical point 72 of a set screw 74, and entering the bore 48. through a passage 68, enters the conduit 82 by the passages afforded between the hexagonal faces of the valve 46 and the circular bore 48. The water therefore enters the machine at a slow rate dependent on the adjustment of the restriction 70. The lower part 10 is provided with a permanently open drain which extends tangentially rearwardly in relation to the direction of circulation of the liquid agitated within the part 10. The water is prevented normally from escaping from the part 10 by centrifugal action of the water past the drain. However when the level of the water reaches a predetermined level the downward static pressure thereof preponderates over the centrifugal action of the water, so that it then begins to escape. The quantity of water therefore increases at a slow rate to this maximum. When the washing operation is finished the rod 60 is moved upwardly so that the switch 54 swings upwardly to open the motor circuit and the spring 50 closes the valve 46. In a machine capable of holding a maximum quantity of 3.5 litres of liquid the maximum cleaning effect was attained by restricting the rate of supply of liquid to a value between one third and one fifth of that without the use of flow-restricting means.