Patent GB-505816-A (GB)
Title: Improvements in and relating to dish-washing machines
IPC: A47L15/06
Filed: 1938-08-23
Abstract: 505,816. Washing dishes. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 23, 1938, No. 24788. Convention date, Aug. 27, 1937. [Class 138 (i)] A dish-washing machine of the general character disclosed in Specification 482,089 and comprising a vat 10 with a dish rack 14, a drain valve 20 controlled by a knob 24, a water supply 30, 31 controlled by a spring- closed valve 32a, and an impeller 16 driven by a motor 17 an electromagnet in the circuit of the motor being operative to allow the valve 32a to close when the vat is full, is provided with a control knob 33 having three operative positions. In the first, the motor only is. energized so that the impeller is driven ; in the second, the valve 32o is opened and the electromagnet also is put in circuit, so that the vat fills with water until the increasing load on the impeller is operative, through the electromagnet, to close the valve ; in the third, the valve is opened and the motor only is energized ; this position is nsed in starting- up the apparatus, and the knob 33 is returned automatically, when released, to the second position where the electromagnet also is in circuit. The knob also is returned automatically from the second to the first position, where the motor only is in circuit, when the electro. magnet operates to close the valve. Further, means are provided for preventing operation of the apparatus when the door 13 of the vat is open, and for locking the door in closed position when the knob 33 is turned to start the apparatus, The knob 24 controls the drain valve 20 through a lever 27 and cable 22, Fig. 7. The knob 33 is fixed on a shaft 34 which carries a cam 38 adapted, in the second position of the knob, to open the supply valve 32a through linkage 43, 42, 39. The knob is latched in this position by a spring-pressed catch 47a on a lever 47, Fig. 2. The motor 17 is in circuit with the mains 67, Fig. 11, through the electromagnet 51 and switches 53, 56 and 54, 57 controlled by a cam 59 on the shaft 34. The cam, is such'that in the firstrosition, b, of the knob, both switches are closed, the motor being driven and the electromagnet shorted; in the second position, c, the switch 54, 57 is open so that the electromagnet is in circuit with the motor and is operative, when the load on the motor rises, to rock the lever 47 and so release the cam 38 and allow the supply valve to close ; in the third position, d, both switches are closed. The knob is held in its " off " and first positions a and b by a spring detent 64, Fig. 4, adapted to engage notches 61, 62 in a plate 60 on the shaft 34. The detent, by engagement with a cam surface 63 on the plate, tends to return the knob automatically from the second and third positions to the first position. A plate 69, on the shaft 34, having lost motion relatively to the cam 38, is operative, when the knob is moved manually from the second to the first position, to raise the catch 47a and allow the supply valve to close. The shaft 34 carries a further cam 81, Fig. 13, which co-operates with a lever 78 pivoted, by a pin-and-slot connection 79a, to a door catch 71, so that the latter is raised, to release the door 13, when the knob 33, is in the " off "position. In this position, the latch is locked, by a tongue and slot 82, 83, so that the knob cannot be turned. When the door is closed, the tongue is disengaged from the slot. If, now, the knob 33 is turned to its first position to start the apparatus, the lever 78 slides the catch 71 into engagement with a clip 77 in a recess 76 in the upper edge of the door, so that the latter is locked in closed position. The cam 81 is so shaped that movement of the knob 33 to its second and third positions does not move the latch. Specification 505,817 also is referred to.