Patent GB-675309-A (GB)
Title: Improvements in dish washing machines
IPC: A47L15/46
Filed: 1949-08-17
Abstract: 675,309. Dishwashing machines. HARRISON, G., NEAL, C. H., and SHELDON, S. R. Aug. 17, 1950 [Aug. 17, 1949], No. 21379/49. Class 138 (i). A dishwashing machine of the type in which dishes and the like are supported on racks in a closed washing compartment, has control means which on being set into operation manually, function automatically to deliver a quantity of water to the compartment, secondly to pump the water through spray nozzles and thirdly to empty the compartment, and a unitary control valve member serving to. admit water to and drain water from the compartment. General construction.-The machine, Fig. 1, includes a dishwashing compartment 1 containing racks or the like for supporting the various articles and of which those for cups are pivotably mounted, reaction rotated water spray tubes 5 within the compartment, a hinged lid 2, and a cold water cistern 6 outside the compartment which is supplied from a water main through a ball and valve and communicates with a tank 8 having a thermostatically controlled electric heater 9. Mounted under the compartment 1 is a pump 4 driven by an electric motor 3. To the side of the compartment 1 is a rotatable valve 10 which can place the tank 8 in communication with the compartment I or place the compartment in communication with a waste pipe. This valve is operable by a solenoid 11. Mounted on a bracket 79 is a timer control comprising a motor 18 and three cam discs 14, 15 and 16. The machine is also provided with fuses 12 for the electrical control circuits, a main switch 80, green and red indicator lights 75, 76 for the circuits of the timer motor 18 and heater 9, and a manual push button 47. Water circuits and control valve.-As shown in Fig. 4 the cistern 6 connects by a pipe 7 to the bottom of the tank 8. A pipe 27 on top of the tank 8 communicates by a T connection to an overflow 28 in the cistern and a pipe 29 connected with an inlet port in the valve 10. Immediately opposite the inlet port is an outlet port connected by a pipe 30 to the compartment 1. The valve 10 also has another inlet port connected by a pipe 32 to the drain 78 of the compartment 1 and also to the inlet 31 of the pump 4. Immediately opposite this second inlet port the valve has another outlet port connected to waste by a pipe 33. The outlet of the pump 4 connects with horizontally disposed spray tubes 5 of triangular cross-section having nozzle outlets 5a. The valve 10 comprises a housing 45-46, Fig. 8, a valve disc 38 provided with two diametrically opposed holes adapted to register during the operation of the machine with the pairs of inlet and outlet ports of the valve. The disc 38 is rotatable through six positions spaced angularly, 60 degrees apart, by a shaft 36 through the medium of a rocker arm 34 loose on the shaft and carrying a spring loaded pawl 41 which is engageable with teeth on a racket 37 fixed to the shaft 36. One end of the rocker arm 34 is connected by an adjustable rod to the solenoid 11 while the other end is connected to a dashpot device. Thus when the solenoid is actuated the rocker arm pawl drives the ratchet and thus the valve disc through 60 degrees. When the solenoid is de-energised the pawl slides back over the teeth with the rocker arm under gravity. The initial position of the valve disc is such that one of its holes registers with one of the valve ports so that the compartment 1 is connected to waste by pipes 32, 33. In the next position, the connection between pipes 32, 33 is closed and connection between pipes 29, 30 is made so that water can flow to the compartment. The next position of the valve disc causes all valve ports to be sealed off while in the next position the pipes 29, 30 are sealed and pipes 32, 33 are connected, this time through the second diametrically opposite hole in the valve disc. The valve disc is then passed through the above steps again until the initial position is again obtained. Timer control mechanism.-As shown in Fig. 2 the motor 18 drives a shaft 17 on which are mounted the three cams 14, 15 and 16. The cam 14 which controls the timer motor itself once the machine is manually started has one recess cut in it. The cam 15 which controls the pump motor 3 has two long but unequal recesses cut in it so that the rinsing operation is shorter than the washing operation, while the cam 17 which controls the solenoid 11 has six recesses cut in it corresponding to the six positions of the valve disc 38. Pressed by springs on each cam disc are followers 22 which are freely mounted on a shaft 20 and mechanically connected to rockable mercury switches 23. In the case of the cam 14 when the follower is in its recess the switch 23 is broken whereas in the case of the other two discs when the followers are in the various recesses the switches 23 are made. When the push button 47 is made electricity is supplied to the motor 18 which then rotates and in so' doing the follower 22 is removed from the single recess in the disc 14 and its switch 23 is thereby made to retain the circuit of the motor 18 until the disc 14 has turned through one complete revolution when the switch 23 is again broken. Operation.-When dishes have been placed in the compartment 1, the lid closed and the main switch 80 made, the push button 47 is depressed manually to start the time motor 18. The valve disc 38 is then caused to move through 60 degrees by the operation of the solenoid 11 by cam 16 so that water is supplied to the compartment 1. The valve disc is then moved so as to prevent further flow of water to the compartment. Cam 15 then causes the pump motor 3 to operate so that water is pumped from the bottom of the compartment to the springs 5 which then rotate by water reaction and effect the washing of the dishes. The motor 3 is' then stopped and the valve disc moved so as to effect the emptying of the compartment. The cams 15 and 16 then cause the same sequence of operations to effect the rinsing operation after which the timer motor is disconnected from the electric supply and the compartment is connected to waste. The cold water supply and heater tank may be replaced by having a direct connection to a supply of hot water. Detergent may be added to the compartment prior to the washing operation. The term cam discs include several alternatives or mechanical equivalents thereof which are described. Specification 603,771 is referred to.