Patent GB-762820-A (GB)
Title: Improvements in and relating to dishwashing apparatus
IPC: A47L15/46
Filed: 1954-09-29
Abstract: 762,820. Dishwashing machines. GENERAL ELECTRIC CO. Sept. 29, 1954 [Sept. 29, 1953], No. 28117/54. Class 138(1) A dishwashing apparatus comprises means for automatically performing the following sequence of operations:-(1) Preliminary rinsing with hot water, (2)' washing with hot detergent solution, (3) Rinsing with hot water, (4) Washing with cool detergent solution. The object of the sequence is to prevent " spotting " of the dishes being washed and the embodiment further provides automatic means for draining the apparatus to preserve about half of the cool detergent solution to which is added cool clean water for another cool detergent wash at reduced strength of solution; the process being repeated a number of times with decreasing strengths of solution before the solution is totally drained away and the dishes given a hot rinse followed by a period in which the dishes are automatically dried by hot air. The hot rinsing water and hot detergent solution are preferably used at about 150‹F, and the cool 'detergent at below 100 ‹F. General arrangement of the first embodiment. The dishwashing apparatus comprises a cabinet 2 containing a vertically disposed vat 3 to which access can be had by way of a door 4 hinged about its lower edge and sealed about it periphery. At the bottom of the vat 3 is an impeller 5 driven by a motor 7 to throw water from a sump 6 upwardly at the dishes contained in a rack R. Hot water is admitted by a solenoid operated valve 9 which is connected by way of Y-junction 11 and pipe 12 to a spraying device 14 at the top of the vat 3. Cold water is similarly admitted by a solenoid operated valve 16 connected to the other branch of the Y-junction 11. A drain fixture 22 in the bottom of the sump 6 is connected by a flexible tube 21 to a drain pipe 23.1. A solenoid 20.1 is adapted when energized to raise the centre portion of the tube 21 above the normal level of the liquid in the vat to close the drain connection. A standpipe 24 passes through the bottom of the vat and communicates directly with the drain pipe 23.1. The upper end of the standpipe 24 is closed by a cap 26 but has apertures at a height above the bottom of the sump such that, with the impeller 5 inactive, the standpipe 24 will drain about half the normal liquid content of the vat 3. When the impeller 5 is working and the vat is fully charged with liquid the liquid level is not as high as the standpipe and no substantial drainage occurs thereby. A heating element 28 surrounds the impeller 5 and is used to heat air circulated by the impeller 5 to dry the dishes. A multiple detergent dispenser 29 as described in Specification 725,913 automatically supplies detergent for the first hot wash. and the first cold wash. A safety switch is incorporated in the door 4. Automatic operation of the first embodiment. A timing motor 39, Fig. 10, drives cams C3, C4, C5 mounted on a shaft 35 and also drives cams C1, C2 on a shaft 31 geared to shaft 35 by gear wheels 38, 38.1. A manual control 32 on the front of the cabinet 2 is connected to the shaft 31 and the motor 39 transmits drive through a clutch 37. The cam C1 operates the switch S1 and so on. The circuit shown in Fig. 10 is energized by a voltage applied between conductor 42 and the earthed conductor 42.1 connected to contact " X " of switch S1. From O to 60 degrees of the cam chart is the " off " condition of the circuit and the only contact made is S3.1 which short circuits the marginal relays R40, R40.1 which would otherwise be in series with the impeller motor 7. To start the sequence the manual control 32 is rotated to an " on " position when contacts '" X " and " Y " are made by cam C1 to start the cam motor 39 and the impeller motor 7. At the same time contact S2.1 is made to supply a voltage to one side of the solenoids 9.1, 16.1 and 20.1. After a brief interval cam C3 breaks contact S3.1 and makes contact S3.2 thereby putting the relays R40, R40.1 in series with motor 7 and energizing solenoid 9.1 of the hot water valve 9. Some of the hot water is caught by the impeller and is thrown back at the dishes but otherwise drains away until, after about 45 seconds, contact S5 is made by cam C5 to energize solenoid 20.1 and close the drain valve after which the hot water accumulates in the vat 3 putting an increasing load on the motor 7 which increases its armature current. Hot water continues to accumulate until either the armature current actuates the marginal relay R40 to break the circuit energizing solenoid 9.1, or cam C3 breaks contact S3.2 and makes contact S3.1 which has the same effect. As it is forcefully circulated in vat 3 the hot water takes a supply of detergent from the dispenser 29. At the end of the hot washing period cam C1 breaks contact " Y " to stop the impeller motor 7 while cam C5 breaks contact S5 to open the drain. After a time, to permit the hot water to drain away, the impeller motor 7 is restarted and the solenoid 9.1 is energized by cam C3, which also puts the marginal relays in circuit again, thuscirculating hot rinsing water with the drain connection open. At the end of the rinsing period cam C5 makes contact S5 to close the drain, cam C3 puts switch S3 in neutral to de-energize solenoid 9.1 thereby stopping the supply of hot water and leaving the marginal relays in circuit, while cam C4 makes contact S4.2 to energize solenoid 16.1 of the valve. 16 which supplies cold water until either marginal relay 40.1 de-energizes solenoid 16.1 or cam C4 breaks contact S4.2 and makes. contact S4.1, the latter contact short circuiting the relays while the former breaks. the circuit to the solenoid 16.1. Cold water is now circulated by the impeller and automatically collects a final charge of detergent from the dispenser 29 for the cold washing period which continues until cam C1 breaks contact " Y " to stop the impeller when water accumulates in the sump and a substantial proportion is drained away through the standpipe 24. The impeller motor is then restarted by cam C1 making contact " Y " and at the same time cam C4 admits a fresh supply of cold water to dilute the remaining solution the quantity of fresh water being controlled by the marginal relay, or in any event cam C4, as above described. This process of washing with a diluted solution using the stand pipe 24 is repeated twice more but at the end of the last wash, when the impeller motor is halted by breaking contact " Y ", the drain valve is opened by making contact S5 with cam. C5 for sufficiently long to drain the vat 3, while cam C4 places switch S4 in neutral. When the vat 3 is drained cam C1 restarts the impeller motor 7, cam C3 makes contact S3.2 to admit hot water and breaks contact S3.1 to bring the marginal relay R40 in circuit, while cam C5 makes contact S5 to close the drain valve. The vat 3. then fills as before described for a period of hot rinsing at the end of which cam C5 breaks contact S5 to open the drain by deenergizing solenoid 20.1 which will in any case be de-energized by cam C2 which breaks contact S2.1 and also makes contact S2.2 to bring the heating element 28 into circuit. The impeller is kept running by cam C1 to circulate hot air for a while but is switched out of circuit for the last period of the whole washing cycle when the heating element and cam motor 39 alone are in circuit both of these being switched out when the cams complete one cycle. General arrangement of the second embodiment. The arrangement is the same as in the first embodiment except that the drainage system is modified. To retain a proportion of the cold detergent solution the stand pipe 24 may be dispensed with and the arrangement shown in Fig. 11 used. There is one exit from the sump 6 which is connected directly to the drain pipe by way of a pipe 64 under the control of a solenoid operated valve 66, or is connected to a tank 60 by way of a short pipe containing a solenoid operated valve 65. Water entering the tank 60 from the sump accumulates in the tank until it spills into a stand pipe 61 which connects with the drain pipe. The measured quantity remaining in the tank can be drawn off and recirculated through the dishes by a pump 67 connected to the spray device 72 at the top of the vat 3. Automatic operation of the second embodiment. Fig. 14 shows the valve solenoids, pump motor. 73, impeller motor 7, cam motor 39 and heater 28 in circuit with their controlling cam actuated switches. No marginal relays are shown to control the hot and cold inlet valves although these may be incorporated. Once the cam motor 39 is started by cam C1.1 closing contact Y hot water is first admitted to the vat by closing contact S3.1 to energize solenoid 9.1. The motor 7 to drive the impeller is then energized, though it may be energized earlier, and at the same time cam C5.1 makes contact S5.1<SP>1</SP> to close drain valve 66 thus completely closing the drain as the solenoid 65.1 closing valve 65 is already energized by cam C6.1. When sufficient hot water has been admitted cam C3.1 breaks contact S3.1<SP>1</SP> and the hot detergent wash continues. At the end of the wash contact Y is broken by cam C1.1 to stop the impeller while cam C5.1 breaks contact S5.1<SP>1</SP> to open drain valve 66. When the solution is drained away cam C3.1 makes contact 53.1<SP>1</SP> to open the hot water valve 9 to spray the dishes with the drain open and the impeller inactive, though this may be used if desired. At the end of the hot rinse period cam C3.1 switches off the hot valve 9, cam C4.1 switches on the cold valve 16, while cam C1.1 switches on the impeller and cam C5.1 closes the drain valve 66. Cold water accumulates in the vat 3 until the cam C4.1 breaks contact S4.1<SP>1</SP>. Detergent is collected from the dispenser 29 and the cold detergent wash proceeds until cam C1.1 stops the impeller 5 and cam C6.1 opens contact 56.1<SP>1</SP> to open valve 65 and drain the vat 3 via the t