Patent GB-557678-A (GB)
Title: Improvements in and relating to dish-washing apparatus
IPC: A47L15/44
Filed: 1942-12-03
Abstract: 557,678. Washing plates &c. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 3, 1942, No. 17211. Convention date, Dec. 5, 1941. [Class 138 (i)] An apparatus for washing dishes &c. in which the articles are placed in a chamber or vat 20 and are subjected to a timed washing cycle including washing, rinsing, and drying steps is constructed with a control member consisting of a cam 90, Fig. 7 for controlling the operations, the cam being driven by a timing motor 107 which drives the control member by reduction gearing 108, Fig. 12 and a gear 111 which is lowered out of driving- connection at the end of the cycle of operations, thereby permitting a spring 113 Fig. 7, to return the control cam 90 to its original position. The apparatus comprises a door 15 closed by a pivoted latch 16, Fig. 1, which controls a switch 116 adapted to prevent operation of the electric controls unless the door is closed, and which causes return of these controls to initial position whenever the door is opened. The water inlet is controlled by a valve 27 closed by a spring and opened by the energization of an electromagnet 28. A drain valve 32 is normally open and is closed by the energization of an electromagnet 37. The impeller 21 for spraying the liquid is driven by an electric motor 23, and an electric heater 41a is provided to effect the final drying operation. The amount of water admitted by the valve 27 is controlled by a coil 55, termed a " measuring coil," which is normally in series with the armature of the motor 23 and which acts to cause the valve 27 to be closed when the impeller meets with resistance due to the presence of a predetermined quantity of water in the vat. The coil 55 acts by withdrawing a spring-controlled core 54 to open a switch 45, 48, and shunt the coil 28 of the magnet which holds the valve 27 open. The cam 90 is formed with raised surfaces 92, 93, 94, 95, Fig. 9, on its lower surface which control spring contacts 72, 73, 74, 75 forming part of a time control switch 68. The upper part of the cam controls a spring contact 71 secured to a fixed terminal 76. The contacts 72, 73, 74, 75 are connected to fixed terminals 77, 78, 79, 80 on the underside of the base, and other contacts connected with the spring contacts are indicated in the diagram Fig. 13, and are mounted on a switch panel 42. To commence operations the door 15 is closed, and in this position the switch blades 71, 75 are closed and the other blades open. A switch button 115 is operated to start the cycle and it energizes an electromagnet 133, 134 which closes a main switch 127, 129 thereby completing the circuits to the impeller motor 23 and the control motor 107. The switch 115 is cut-out of the circuit and a holding circuit for magnet 133, 134 established to keep open the main 'switch. At the start the valve 27 is closed and the valve 32 is open but movement of the motor 107 causes closing of the contact 73 thereby causing the valve 27 to open and the liquid is directed to a preliminary spraying device which may be at the upper part of the vat. The cam 90 then closes contact 72 causing energization of the coil 37 which closes the drain valve 32 and at the same time a detergent is admitted to the vat by means of a cable 68 connected to the spring 41 of the drain valve 34. The water now accumulates in the vat 20 and at a pre-determined interval switch blade 75 closes and causes energization of the coil 55, which, as explained above, de-energizes the magnet 28 and cuts off the water supply. The impeller now acts for a predetermined interval to circulate the liquid, and then the switch blade 72 is operated to open the drain valve. The water supply valve is then opened to spray the dishes for a second time and after an interval the drain valve is again closed. The measuring coil 55 is then put into the circuit and rinsing water is supplied until the coil 55 again causes closing of the valve 27. The impeller then circulates the rinsing water until the drain valve is again opened. The valve 27 is then opened for a final spray, followed by a final rinse by the circulation of water by the impeller. The operations are completed by closing the connections to a heating coil 41a, and with the valve 27 shut, valve 34 open, the impeller circulates heated air to effect the drying of the dishes. Ultimately, the switch blade 71 is opened by the cam 90 and all the circuits are de-energized, and the spring 113 restores the cam 90 to its initial position for a repeat cycle. This also occurs if the door 15 is opened at any time during the cycle of operations.