Patent GB-665691-A (GB)
Title: Improvements in dishwashing machines
IPC: A47L15/06
Filed: 1949-04-28
Abstract: 665,691. Dishwashing machines. TRIUMPH DISHWASHERS, Ltd. April 28, 1949 [May 1, 1948], No. 11352/49. Class 138 (i) Relates to an automatic dishwashing machine comprising a washing chamber with a closure, and a liquid circulating impeller assembly arranged centrally in the bottom of the chamber, wherein the bottom slopes inwardly towards the centre and is formed with a sump extending from adjacent the centre to adjacent the perimeter and sloping inwardly towards the centre thereof to return liquid to beneath the impeller assembly, which sump has an overlying screen which terminates short of the outer end of the sump to define an unscreened opening through which food soil can pass to be trapped beneath the screen so as to be prevented from recirculating and subsequently removed. General construction. -The machine comprises a casing 2, Figs. 1 and 3, in which is mounted a square shaped chamber 1 having a hinged closure lid 44 counterbalanced bv springs 94 and unlatchable at 46 by a plunger 50. Mounted in the bottom of the chamber is an impeller assembly 9, Fig. 4, which may be of the type disclosed in Specification 605,298. The assembly 9 comprises, a fixed casing 16 to which are secured curved vanes 16', and impeller blades 15 rotatable with a shaft 6 coupled by a sleeve 7, Fig. 4, to the shaft 8 of an electric motor 5. Mounted on the shaft 6, within an opening 23 in the casing 16 is a distributer 19 of the type disclosed in Specification 660,860, [Group XXIX], having an under deflecting surface 20 twisted spirally to form a continually changing deflecting angle from below the horizontal at the portions 21 to the vertical deflecting portion as at 22. A sump 24 extending from the impeller assembly to one corner of the chamber is covered by a removable fine mesh screen 26, Fig. 2, except for an opening 29 near the corner of the chamber. Air vents 38 and 39, Fig. 3, are provided in the bottom and the upper portion of the chamber respectively. Liquid supply and draining means.-Hot water is supplied from a tank 74, Figs. 1 and 2, pipe 73, inlet valve 75 controlled by a solenoid 76 to a water inlet 37, Fig. 4, positioned above the level of the vent 38 and directed to spray water over the screen 26. A cam operated drain valve 31 is provided in the bottom of the sump 24. The valve 75 is of the type disclosed in Specification 660,859, [Group XXIX]. Control motor mechanism.-An electric motor of a slow speed control mechanism 77, Fig. 7, drives a shaft 78 on which are mounted a cam 80 which actuates a micro switch 87 to energise the solenoid 76, a cam 81 which actuates a switch 89 controlling the circuit of the impeller and control motors, and a cam 79 which actuates the drain valve 31 mechanically. The switch 89 is in parallel with a manual push button 90, Fig. 1, arranged within the casing 2. A switch 51, Fig. 3, arranged with the casing 2 is broken, when the lid 44 is opened, to de-energise the control mechanism and thus prevent scalding of the operator. Operation.-Dishes are placed in their baskets within the chamber 1 together with a suitable detergent and the lid 44 is closed thereby closing switch 51 and preparing the circuit of the control mechanism. At this moment the cam 81 is positioned so that switch 89 is open, the cam 80 is positioned so that the inlet valve is closed and the cam 79 positioned so that the drain valve is open. On operating the push button 90 the switch 89 is byepassed and the impeller and control motors are energised. The cam 81 then closes the switch 89, cam 79 closes the drain valve, and the cam 80 operates the switch 87 to energise the solenoid 76 and thus operate the valve 75 which is arranged to supply a constant volume of water at constant pressure to the inlet 37. The inlet valve then closes and the impeller forces water through the opening 23 where it is deflected by the rotating distributor 19 to all parts of the chamber 2. During this washing operation particles of food soil will in time be passed through the opening 29 to the sump 24 where they will be prevented from recirculating by the screen 26. The drain valve is then opened by the cam 79 to clear the soiled water and food particles from the chamber. Any food particles adhering to the screen 26 are washed off by the action of the receding water on the screen but to ensure that it is perfectly clean the cam 80 operates the valve 75 before the drain valve recloses and the incoming spray from the inlet 37 dislodges any remaining particles from the screen and washes them down the drain. The drain valve then closes and the inlet remains open until the chamber has been supplied with hot water for rinsing, when it recloses. When the rinsing operation is completed, the drain valve is again opened. The impeller continues to rotate and thereby draws in air through the vent 38, forces the air over the dishes to effect a drying operation and out of the vent 39. After a short interval of time the cam 81 operates to open the switch 89 and interrupt the power to the impeller and control motors. The machine is then in readiness for the next cycle of operations. The lid may be left closed so that the dishes continue to dry in their own heat by a natural draught through the vents 38, 39.