Patent GB-769040-A (GB)
Title: Improvements in and relating to dish washing machines
IPC: A47L15/06
Filed: 1954-12-30
Abstract: 769,040. Dishwashing machines. GENERAL ELECTRIC CO. Dec. 30, 1954 [Dec. 30, 1953], No. 37678/54: Class 138(1)  A dishwashing machine comprises a tub 2, Fig. 1, adapted to hold liquid, impeller means 27.for circulating liquid within the tub, together with a centrifugal pump having a rotatable pumping member 41; 42, Fig. 3, disposed in a chamber 7 at the base of the tub, a conecting passageway 51 between the tub 2 and chamber 7, a drainage opening 26', Fig. 2, leading from the bottom of the chamber 7 for gravity drainage while the pump is inoperative and baffle means 53, 54, 55 within the chamber 7 so arranged that while the pump is operative, it either directs liquid from the chamber 7 to the tub via the passageway 51 and away from the opening 26<SP>1</SP> or alternatively it directs liquid through opening 26<SP>1</SP>, depending upon the direction of rotation of the. pump. The dishwashing machine, Fig. 1, includes a cabinet, a wash tub door 4, a motor 15 for driving the pump and impeller 27, a heating element 34, a solenoid operated liquid inlet valve 21 and a controllable timer motor 60 which drives in known manner a series of cam-controlling switches in the circuits of the impeller motor, the liquid inlet valve solenoid, the heater 34 arid the timer motor itself. During a washing cycle of the machine a predetermined amount of liquid is supplied to the tub through the agency of a marginal relay in the motor circuit which operates to de-energize the inlet valve solenoid in known manner, The impeller motor controlling cam, however, in this machine actuates a three' pole double throw switch as described with reference to Fig. 6 (not shown) to reverse the direction of rotation of the motor. Referring to Fig. 3, the centrifugal pump chamber 7 is disposed in sump of the tub 2 coaxial with the impeller 27. A disc member 42 having down-turned blades 41 is rotatable in the pump chamber 7, being connected by arms 47 and yoke 46 to the motor shaft 16, the straps 47 passing through an opening, surrounded by a neck 20 in the top wall 17 of the pump casing. Ears 50 on the straps engage the bottom of the impeller hub 28 to secure the assembly in position. As shown in Figs. 2, 2a the tub 2 is in communication with the. side of the pump chamber by means of a passageway in the form of a cup-like depression 51 and opening 52 in the chamber wall and the top of the pump chamber is in communication with the tub through the neck 20..The bottom wall of the pump chamber. i.e. the sump wall 8, has the drain hole 26<SP>1</SP> and is connected, by pipe 26 and check valve 26<SP>2</SP>, Fig. 1, to a drainage system. Disposed in the pump chamber adjacent the openings 52 and 26<SP>1</SP> are sheet metal baffle members 53. 54, 55 of a depth substantially equal to the depth of the pump chamber. In operation when the disc ,42 is rotated in the direction indicated by arrows in Fig. 2a liquid entering the pump chamber through the hole 52 and neck 20 is prevented from entering the drain hole 26<SP>1</SP> by the baffle 54 and the centrifugal action on the liquid and is returned through the opening 52. An equilibrium condition is reacted in which liquid entering the pump chamber through either hole is immediately returned to the tub and residual liquid in the chamber 7 takes the form of a rapidly rotating annulus. When the motor 15 is stopped, instead of the tub being drained by gravity through the openings 52 and 26<SP>1</SP>, pressure draining is. effected by rotating the pump in the opposite direction to that in which it rotates during a washing operation. The baffle 55 then prevents the rapidly rotating liquid in the chamber 7 from passing through the opening 52 to the tub whilst the baffle 54 then assists in directing the liquid to the drain hole 26<SP>1</SP>. Backflow of liquid through the pipe 26 is prevented by the check valve 26'. Specifications 557,034 and 663,586 are referred to.