Patent GB-694869-A (GB)
Title: Improvements in or relating to dishwashers
IPC: A47L15/48
Filed: 1950-10-04
Abstract: 694,869. Dishwashing machines. HOBART MANUFACTURING CO. Oct. 4, 1950 [Oct. 11, 1949], No. 24239/50. Class 138 (i). Relates to a dishwasher comprising a washing chamber having a door, a liquid supply valve, a drain valve and a sequence timer controlling the washing cycle, wherein the door has a single locking handle controlling a switch connected to the timer and when the switch is opened, by unlocking the handle, the timer is stopped, the supply valve is closed but the drain valve remains in its position as determined by the timer at the moment of opening the .switch. General construction.-The machine, Fig. 2, comprises an outer cabinet 10, housing an inner casing 15 forming the washing chamber to receive dish racks 40, 41, which chamber is provided with a front opening door 44 movable between a vertical closed position and a horizontal open position and lockable and unlockable by a single handle 50. Below the washing chamber is a lower casing 22 defining a sump 25 which is provided with a strainer assembly 29, an overflow pipe 34 and drain valve 27. A pump 35 driven by an electric motor 37, has an inlet 36 in the sump and an outlet connected to a rotatable wash arm 38 in the washing chamber. A housing 95 is provided to one side of the casing 22 and encloses an electric heater 96. Air may be drawn through the housing by a fan 100, driven by an electric motor 101, past the heater and through an opening 91 into the bottom of the washing chamber. This air can then pass out of the machine through a slot 102 provided below the bottom of the door 44. Electric solenoids for operating the drain valve and a hot water constant flow supply valve 66, Fig. 1, and an electric sequence timer 70 for controlling automatically the steps of washing, rinsing and drying are housed in a compartment formed between the front of the cabinet and the casing 22. Sealing means are provided to prevent moisture from reaching this compartment. A manual control 75 operating a rod 76 is provided for initiating the cycle of operations and also provided is a signal lamp 115 which always remains in circuit once a cycle of operations has been. started. The timer embodies a dial 72 suitably marked such as "Wash," "Rinse," " Dry " and " Off." Water supply and draining means. -Hot water is supplied by a pipe 65 to the valve 66 which is controlled by a solenoid 67 so that the valve is opened for a definite period of time. The water flows from the valve 66 by a pipe 68 to the washing chamber. The drain valve 27 is normally biased to the open position by a spring 31 and is closable by an electric solenoid 32 through a spring 33 and lever 30. Door handle mechanism.-As shown in Fig. 3 the handle 50 connects by a shaft 51 to operate locking bars 55 against the urge of a spring 56. The ends of the bars 55 are guided on the door at 58 and carry latching members 60 which engage with keepers 61 on the door frame. When the door is locked as shown one member 60 causes a switch 110 to close and when the door is unlocked by rotating the handle 50 the member 60 is removed from the switch member 112 to cause the switch to open. Operation.-As shown in the electrical diagram of Fig. 7 the motor 71 of the timer operates cams 85 which in turn operate switch contacts 80, 150, 140, 135 and 130. When dishes have been inserted in the washing chamber, the door is closed and switch 110 is " made." Then on depressing the control 75, the rod 76 causes the contacts 80 to " make " and thus energise the timer motor 71 through lines 120, 123, switch 110, line 124, common terminal 125 and line 126 and thus by line 122 to line 121. Once the timer motor starts the switch contacts 80 are held by cam mechanism throughout the rest of the cycle. The control 75 can thus return to its normal position due to a spring 77. Immediately the contacts 80 are made the signal lamp 115 is energised through lines 120, 123 and 128. It will be seen that the drain valve solenoid 32 is controlled directly across the mains 120, 121 by the switch contacts 130. The supply valve solenoid 67 and its switch contacts 135; the pump motor 37 and its contacts 140, and the fan motor 101 in parallel with the heater 96 and contacts 150 are all arranged in parallel with the terminal 125 and line 122 and are all dependent for their electrical supply on the switch 110. The timer motor cams cause the contacts 135, 140, 130 to operate in proper sequence to effect a water supply and washing step; then draining of the sump, a water supply and rinsing step followed by draining of the sump and then by the operation of the contacts 150, a drying step. Finally the timer motor causes the contacts 80 to open, when the dial reaches its " Off " position, and the machine is rendered inoperative. If it is desired to open the door 44 at any point in the cycle to place articles in or take them from the washing chamber the handle 50 is turned to unlock the door and thus break the switch 110. This will cause the timer motor to stop and also prevent water supply to the chamber or if the cycle is in the drying step prevent the energisation of the heater and the fan motor. However the signal lamp will remain alight since the cycle is still incomplete and the drain valve solenoid will be unaffected by the breaking of the switch 110 i.e. if the drain valve was closed at the time of opening the door it would remain closed and if open at the time would remain open. When the door is relocked the cycle will continue from the point at which it was stopped. Thus when the door is opened during a cycle of operations splashing of water or a blast of hot air from the chamber is prevented. Also if the washing or rinsing cycle was in progress at the time of opening the lock the sump would not be emptied of water. Leakage of washing liquid from the machine when in operation is prevented by co-operating baffles on the door and interior of the casing 15 as described with reference to Figs. 4 and 5 (not shown).