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Publication numberUS2825666 A
Publication typeGrant
Publication dateMar 4, 1958
Filing dateMay 12, 1955
Priority dateMay 12, 1955
Publication numberUS 2825666 A, US 2825666A, US-A-2825666, US2825666 A, US2825666A
InventorsEdgar S Stoddard
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Methods of and apparatus for washing dishes
US 2825666 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

METHODS OF AND APPARATUS FOR WASHING DISHES Filed May 1,20 1955 E. S. STODDARD arch 4 95 4 Sheets-Sheet 1 .d mm. T a Nd FM w. S r a W E.

HEATER I41: COLD WATER 5UPPLY METHODS OF AND APPARATUS FOR WASHING DISHES Filed May 12, 1955 Mam-ch 4-, W58. E. s. STODDARD 4 Sheets-Sheet 2 INVENTOR. Edgar S Sfoddard aha March 4, 1958 E. s. STODDARD METHODS OF AND APPARATUS FOR WASHING DISHES 4 Sheets-Sheet 3 Filed maylz, 195s 5 i E; R M 5% 5 552mg mm 532; 555% J a r P v 0 2: 2E a a m h 2 :8 223g A r. 5 i 9 HQE p g 5s 52:: x M NH 3% 2 g o a m an ms 5 SQ c a h a a 9 FE 2 5% o $3228 m EB a E 55% Q $28 8 & QM 5 5 $5: 3 Y & s M\\ 9 mm. L. IQ G R A. L wQ dam u v DEN I g \r E $5 6m 35% 36% QE 3 5 A g g H #5 5 sq m PM M @528 E2 March 4, 195 E. s. STODDARD METHODS OF AND APPARATUS FOR WASHING DISHES IV. I.

4 8w m t him @Esx R a u 5% BI EEG .l |||l m M. x. hams m mm. a E mvw ww r m 1] a s l I M 4 J www E v%% swim u REMMI QWFWWE NQ RR Q EB Qw v 5% -22 HQ 3% 5: Q 15% s b8: $5386 EEE 5% q :r r L fi r 5% 6 395$ Em EQSEB SEE :5 ET M H3 he "5 Q5 mm 355% 1 w IE5 .7 T2 R wfimm 3% m Tum m x W H Xi F. Q Q QM QM Q Q 33 WE kw s m R SE N &5 A E United States Patent IVIETHODS OF AND APPARATUS FOR WASWG DISHES Edgar S. Stoddard, Berwyn, 111., assignor to Genera? Electric Company, a corporation of New York Application May 12, 1955, Serial No. 507,805

37 Claims. (Cl. 134-25) The present invention relates to methods of and apparatus for washing dishes, or the like.

It is a general object of the invention to provide an improved method of and apparatus for washing dishes, or the like, that substantially completely eliminates the deposit of mineral salts thereupon, with the result that the dishes, particularly glassware, have unusual brilliance and sparkle.

Another object of the invention is to provide an improved method of and apparatus for washing dishes, or the like, that involves a control of the pH of the final rinse water, without the utilization of external chemical reagents.

Another object of the invention is to provide an improved method of and apparatus for washing dishes, or the like, that involves converting ordinary hard water into a soft aqueous acid rinse solution capable of dissolving from the dishes any prior deposits of mineral salts thereon.

A further object of the invention is to provide an improved method of and apparatus for washing dishes, or the like, of the character described, wherein the conversion of the hard water into the soft aqueous acid rinse solution is efiected by apparatus for treating the hard water that employs ion exchange.

A further object of the invention is to provide an improved method of and apparatus for washing dishes, or the like, of the character described, wherein the conversion of the hard water into the soft aqueous acid rinse solution is efiected by apparatus for treating the hard water that employs electro-dialysis.

Further features of the invention pertain to the particular arrangement of the steps of the method and of the elements of the apparatus, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which: I

Figure 1 is a front elevational view, partly broken away, of dishwashing apparatus embodying the present invention;

Fig. 2 is a vertical sectional view of the dishwashing apparatus, taken in the direction of the arrows along the line 22 in Fig. 1;

Fig. 3 is a diagrammatic illustration of the water systern incorporated in the dishwashing apparatus;

Fig. 4 is an enlarged vertical sectional view of the water-treatment unit that is incorporated in the water system of the dishwashing apparatus, as illustrated in Fig. 3;

Fig. 5 is a diagrammatic illustration of the electric control system incorporated in the dishwashing apparatus;

Fig. 6 is a combined time and cycle sequence diagram of the operation of the elements incorporated in the electric. control system of the dishwashing apparatus, as illustrated in Fig. 5; and

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Fig. 7 is a diagrammatic illustration of the water system incorporated in a modified form of the dishwashing apparatus.

Referring now to Figs. 1 to 3, inclusive, of the drawings, the dishwashing apparatus 1% there illustrated is of the general construction and arrangement of that dis closed in U. S. Patent No. 2,681,844, granted on June 954, to Forrest A. Walker; which apparatus 10 comprises a cabinet 11 housing a vat 12, {and having aligned front openings, and provided with a front door 13 movable between a substantially vertical closed position and a substantially horizontal open position. The front door 15 is of a double-Wall construction, and the inner wall carries a detergent-receiving cup 13a arranged adjacent to the lower portion thereof and opening into the vat Also, the apparatus 10 comprises open wirework rack structure, not shown, that is movable into and out of the vat 12 when the door 13 occupies its open position; which rack structure is adapted to receive and support the dishes, glassware, or the like, that are to be washed.

The apparatus 10 is also provided with a Water system including an inlet conduit 14 that is connected to a hot water heater, indicated at 14a, that is, in turn, connected to a cold water supply pipe 14b that is adapted to be connected to a suitable source of raw water under pressure, such, for example, as the usual city water main. Also the apparatus 129 comprises a drain conduit 15 that is adapted to be connected to drain plumbing, not shown. (Brdinarily, the source of raw water is at a temperature of about 58 F. to 60 F., and the water heater 14a is operative to supply the water to the inlet conduit 14 at a temperature at least as high as F., and preferably in the general range 135 F. to l5ll F. Arranged in the top of the vat 12 is water inlet mechanism 16 that is adapted to produce a finely divided downwardly directed spray or" hot water; and also arranged in the bottom of the vat 12 is a sump 17 that is adapted to accumulate a charge of hot water for washing and rinsing purposes. Moreover, an impeller 13 is arranged within the sump 17 and operative to produce circulation of the hot water from the sump 17 upwardly within the vat 12, the impeller 13 being operated by an associated electric drive motor 19 carried by the bottom of the vat 12. In the water system, a main inlet valve 2d is arranged between the inlet conduit 14 and the water inlet mechanism 1d, the main inlet valve 2t) being of the solenoid operated type including an operating solenoid 20a. More particularly, the main inlet valve 2%? is normally biased into its closed position and is operated into its open position when the solenoid Ztla is energized. Also in the water system, a drain valve 21 is arranged between the bottom of the sump 17 and the drain conduit 15, the drain valve 21 being of the solenoid operated type including an operating solenoid 21a. More particularly, the drain valve 21 is normally biased into its open position and is operated into its closed position when the solenoid 21a is energized. Specifically, the inlet of the drain valve 21 communicates directly with an opening provided in the bottom of the sump 21, and the outlet of the drain valve 1 communicates with trap structure 22, that, in turn, communicates with the drain conduit 15. in the arrangement, the inlet of the main inlet valve 2-13 is directly connected to the inlet conduit 14-, while the outlet of the maininlet valve 20 is connected to a conduit 23 extending to the water inlet mechanism 16.

Further, the apparatus l9 comprises a we. er treat- .ment unit 30, illustrated in Fig. 4 and described in detail hereinafter; the unit 3% is operative to efiect both demineralization of the raw water and acidification thereof and operates upon principles of both ion exchange .and of electro-dialysis and comprises an outer casing negative terminal of a direct current source of supply. The cathode 31. houses an anode 32 insulated therefrom, as well as a permeable diaphragm or barrier 33 arranged in interposed relation with respect to the cathode 31 and the anode 32. Also an ion exchange bed, indicated at 34, is arranged within the barrier 33 and embedding the anode 32. In .the unit 30 a cathode chamber 35 is defined between the cathode 31 and the barrier 33, and an anode chamber 36 is defined between the barrier 33 and the anode 32, the ion exchange bed 34 being arranged within the anode chamber 36. The bottom and the top of the cathode chamber 35 are respectively provided with inlet and outlet fixtures 37 and 38; and the top and the bottom of the anode chamber 36 are respectively provided with inlet and outlet fixtures 39 and 46. In the arrangement, a flow control device 41 is positioned adjacent to the entrance of the inlet fixture 39, and the anode 32 extends through the inlet fixture 39 in insulated relation therewith to the exterior Where it is connected to the ungrounded positive terminal of a direct current source of supply.

The inlet conduit 14 is connected via a conduit 42, including a manual valve 43, to the inlet fixture 37 of the cathode chamber 35; and the outlet fixture 38 of the cathode chamber 35 is connected via a conduit 44 to the trap structure 22; whereby a catholyte may be conducted from the inlet conduit 14 through the cathode chamber 35 and thence into the trap structure 22 and ultimately into the drain conduit 15. Also the inlet conduit 14 is connected via a conduit 46, including an auxiliary inlet valve 47, to the inlet fixture 39 of the anode chamber 36; and the outlet fixture 40 of the anode chamber 36 is connected via a conduit 48 to the lower portion of the vat 12 somewhat above the sump 17; whereby an anolyte may be conducted from the inlet conduit 14 through the anode chamber 36 and thence into the vat 12. The auxiliary inlet valve 47 is of the solenoid operated type including an operating solenoid 47a; the auxiliary inlet valve 47 being biased into its closed position and operated into its open position when the solenoid 47a is energized.

An upstanding substantially cylindrical screen 49 is arrangcd in the sump 17 in surrounding relation with respect to the impeller 18 in order to prevent foreign material, lettuce leaves and the like, from being caughtup and flung by the impeller upwardly through the vat 12 and into the rack structure, not shown, supporting the dishes to be washed; and also an electric heating unit 50 is arranged in surrounding relation with respect to the impmeller 18 and below the rack structure mentioned, the heating unit 50 being employed in the drying of the dishes in conjunction with the impeller 13, as explained more fully hereinafter. Preferably, the heat ing unit 50 is of the sheathed resistance conductor type so that it is impervious to the water in the vat 12.

Further, the apparatus 16 comprises a program con troller, indicated at 51, and provided with a manual control dial 52, as well as a door switch 53 operatively associated with the front door 13, a control switch indicated at 54, a rectifier unit indicated at 55, a measuring coil or relay indicated at R56, and a source of current supply of 118-volts, single-phase, 60-cycles. rangement, the door switch 53 may be secured to the vat 12 adjacent to the front openingthereinto and is operated into its respective open and closedpositions by movements of the front door 13 into its respective open and closed positions. The program controller 51 may be arranged in the top of the space disposed between the left-hand wall of the cabinet 11 and the lefthand wall of the vat l2; and likewise, the elements 54, 55 and R56 may be disposed in the space mentioned below the program controller 51.

In the ar-- The program controller 51 t a,eae,ees I 7' front end of the shaft mentioned exteriorly of the front wall of the cabinet 11. As indicated in Fig. 1, the unit 39 may be mounted upon a bracket 57 secured to the lefthand side wall of the vat 12, whereby the unit 30 is disposed below the elements 51, etc. and between the lefthand side wall of the cabinet 11 and the bottom wall of the vat 12.

Considering now in greater detail the construction and arrangement of the water treatment unit 30, and referring to Fig. 4, the cathode 31 is of elongated tubular form; the anode 32. is of elongated rod-like form; and the permeable diaphragm or'barrier 33 is also of elongated tubular form; preferably, the cathode is formed of stainless steel and is substantially cylindrical being provided at the lower end thereof with an inwardly directed annular flange 61 and being provided at the upper end thereof with an outwardly directed annular flange 62. Preferably, the anode 32 is formed 'of carbon or graphite and is substantially cylindrical and arranged along the longitudinal axis of the unit 36. Preferably, the permeable barrier 33 is formed of ceramic material and is substantially cylindrical and arranged in interposed relation with respect to the cathode 31 and the anode 32 and concentric therewith. Thus the cathode chamber defined between the cathode 31 and the barrier 33 is substantially annular, and the anode chamber 36 defined between the anode 32'and the barrier 33 is substantially annular.

The opposite lower and upper ends of the cathode 31 are closed by a pair of longitudinally spaced-apart substantially disk-like insulating plates 63 and 64. The lower 7 plate 63 is supported upon the lower flange 61 with an annular sealing gasket 65 arranged therebetween; and

the upper plate 64 is secured in place by an associated clamping ring 66 disposed thereabove, an annular sealing gasket 67 being arranged mutually between the upper plate 64, the clamping ring 66 and the adjacent upper end wall of the cathode 31. More particularly, the barrier 33 is clamped in position between the plates 63 and 64 by the arrangement including the clamping ring 66, the upper face of the lower plate 63 having an annular groove 68 therein receiving the adjacent lower end of the barrier 33, and the lower face of the upper plate 64 having an annular groove 69 therein receiving the adjacent upper end of the barrier 33. In the arrangement, two sealing gaskets 7t and 71 are respectively arranged in the grooves 68 and 69 and respectively en age the lower and upper ends of the barrier-33, thereby to form a liquid-tight seal is provided with a rotatable operating shaft that projects between the cathode chamber 35 and the anode chamber 36. The clamping ring 66 may be secured in place to the adjacent annular flange 62 disposed therebelow by a plurality of screws 72 provided with associated nuts 73 in order to complete the assembly. In the arrangement, the plates 63 and 64 may be formed of phenol-formaldehyde condensation products; the gaskets 65, 67, and .71 may be formed of neoprene, and the clamping ring 66 may be formed of any suitable material.

The anode 32 extends through longitudinally spaced apart and aligned openings formed in the central portions of the plates 63 and 64; and preferably the major portion of the anode 32 is jacketed by a tubular sleeve 74 of insulating material. The upper portion of the sleeve 74 extending through the central opening provided in the upper plate 64 to the exterior of the anode chamber 36 is imperforate and suitably cemented in liquid-tight relation to the adjacent upper portion of the anode 32, as indicated at 75;. while the lower portion of the sleeve 74 extending into ,the anode chamber 36 is perforated, as indicated at 76, to accommodate contact of the anode 32 by the anolyte in .the anodechamber 36. .The extreme lower end of the anode 32 is positioned in the central opening provided in the lower plate 63 by an intervening substantially cup-shaped supporting member 77. In the arrangement, the sleeve 74 and the cup 77 maybe formed of phenol-formaldehyde condensation products.

garages In order clearly to definite thebed 34 and to retain the same in place, a pair of longitudinally spaced-apart substantially disk-shaped reticulated plates or screens 78 and 79'are respectively arranged in the lower and upper portions of the anode compartment 36 within the barrier 33 and in surrounding relation with respect to the anode 32; the lower plate 78 is spaced somewhat above the lower plate 63 by an interposed spacing ring 80 to define an annular chamber 81 therebetween; and likewise, the upper plate 79 is spaced somewhat below the upper plate 64 by an interposed spacing ring 83 to define an annular chamber 84 therebetween. In the arrangement, the plates 78 and 79, as well as the spacing rings 80 and 83, may be formed of phenol-formaldehyde condensation products. Preferably, the porous bed 34 completely fills the space within the anode chamber 36 defined mutually between the sleeve 74 and the barrier 33 and the upper and lower plates 78 and 79; the holes provided in the plates 78 and 79 are of the same size in order to prevent pressure differentials between the chambers 84, 36 and 81 when the 'anolyte is passing in a stream through the anode chamber 36, the holes provided in the plates 78 and 79 being sufficiently small to prevent the escape of the individual particles of the porous bed 34 from the anode chamber 36.

The outer ends of the central openings formed in the plates 63 and 64 are threaded and respectively receive the threaded ends of the lower and upper tubular elements 40 and 86 respectively arranged in liquid-tight relation therewith. An annular array of holes 87 is provided in the lower plate 63 and communicating between the upper "end of the tubular element 40 and the annular chamber 81; and likewise, an annular array of holes 38 is provided in the upper plate 64 and communicating between the lower end of the tubular element 86 and the annular chamber 84. The extreme lower end of the tubular member 40 is threaded in order to receive any desired connecting fitting; and likewise, the extreme upper end of the tubular member 86 is threaded and carries the substantially T-shaped fitting 39 having a longitudinally extending hollow head 89 surrounding the anode 32 and a laterally extending stem 89 receiving the threaded inner end of a tubular member 90, the outer end of the tubular member 90 being threaded to receive any desired connect- 'ing fitting. The upper end of the head 89 is threaded and receives the lower end of a longitudinally extending tubular member 91 also surrounding the anode 32. The upper end of the tubular member 91 is threaded and receives a substantially cup-shaped fitting 92 also surrounding the anode 32. -A substantially sleeve-like compressible sealing gasket 93, that may be formed of neoprene, is arranged within the upper end of the tubular member 91 and within the fitting 29 in surrounding relation with the sleeve 74'and retained in compression by the fitting 92 in order to provide a liquid-tight joint or gland closing "the upper end of the tubular member 91 and sealing the "same with respect to the exterior. The extreme upper end of the'sleeve 74 and the anode 32 project through a central opening 94provided in the fitting 92 to the exterior; and the extreme upper end of the anode 32 projects beyond'the extreme upper end of the sleeve 74 and carries a terminal strap or fixture 95 that is adapted to be connected to the previously mentioned ungrounded positive terminal of the direct current source of supply. Also a terminal strap 96is-secured to the cathode 31 and adapted to be connected to the previously mentioned grounded negative terminal of the direct current source of supply.

Further, the previouslymentioned flow control device 41 may take the form of plug 97 arranged in the outer end thereof may be somewhat distorted in response to an abn'crmalpressure in'the inlet supply conduit14 connected thereto, so as to reduce the effective cross-sectional area of the hole 98 thereof with the consequent flow-regulating effect with respect to the passage of water into the fitting 39. Inother words, the flow control plug 97 is designed to accommodate the passage through the hole 98 of a substantially fixed fiow of water, when the tubular member is connected to the household hot-water plumbing, involving the usual water pressures encountered therein. Finally, the two tubular fittings 37 and 38 are respectively secured in liquid-tight relation with lower and upper openings provided in the wall of the cathode 31 and communicating with the respective lower and upper ends of the cathode chamber 35.

In the arrangement, it will be understood that after removal of the fitting 92 from the tubular member 91, the anode 32 may be withdrawn from the upper end of the unit 30 for adjustment, repair or replacement, as required. Also, it will be appreciated that a controlled fiow of water into the tubular member 90 downwardly through the anode chamber 36 and from the tubular member 40 is effected upon opening of the auxiliary inlet valve 47 arranged in the conduit 46 connected to the tubular member 90; and likewise, a flow of water is established into the inlet conduit 37 upwardly through the cathode chamber 35 and out of the outlet conduit 38 upon opening of the manual valve 43 arranged in the conduit 42 connected to the inlet conduit 37; whereby the stream of water flowing downwardly through the anode chamber 36 is in counterfiow relation with respect to the stream of water flowing upwardly through the cathode chamber 35. The stream of water flowing through the anode chamber 36 readily penetrates the porous ion exchange bed 34 therein and is in wetting relation therewith; and also this stream of water is in wetting relation with the barrier 33 and the anode 32 by virtue of the perforations 76 provided in the in sulating sleeve 74. Further, the stream of water flowing through the cathode chamber 35 is-in wetting relation with the barrier 33 and the cathode 31.

Moreover, the ungrounded anode 32 is completely electrically insulated from the grounded cathode 31 and the other grounded elements 39, etc., of the unit 39; whereby the application of a potential between the anode 32 and the cathode 31 effects an electrolytic action upon the two streams of water respectively traversing the chambers 35 and 36 and upon the ion exchange bed 34.

Turning now to the composition of the ion exchange bed 34, it preferably comprises a mixed bed of discrete particles of cation exchange material and discrete particles of anion exchange material, although it may comprise only discrete particles of cation exchange material. Specifically, it is preferable that the porous bed 34 comprises first discrete particles of a synthetic organic polymeric cation exchange resin,and second discrete particles of a synthetic organic polymeric anion exchange resin, the two types of particles being heterogeneously mixed (about 50%-50% by volume) in the mass of the bed 34, thereby producing approximately equal cation exchange and anion exchange capacities.

More particularly, this cation exchange resin is of bead-like formation and may comprise the strong-acid resin sold by Rohm and Haas under the name Amberlite IR120, and this anion exchange resin is of bead-like formation and may comprise the strong-base resin sold by Rhom and Haas under the names Amberlite IRA- 400 and Arnberlite IRA-410. A cation exchange resin of the type specified essentially comprises a stable insoluble synthetic organic polymer, active acidic functional groups chemically bonded thereto and dissociable into free mobile cations to impart a negative charge to the polymer, and water in gel relationship with the polymer. Similarly, an anion exchange resin of the type specified essentially comprises a stable insoluble synthetic organic polymer, active basic functional groups chemically bonded thereto and dissociable into free mobile anions to impart a positive charge to the polymer and water in gel relationship with the polymer; The active acidic functional groupsattached to the associated organic polymer are orientedwith respect to the interfacesthereof so as to be partially or completely dissociable in the internal gel water into fixed negative ions linked to the polymer and into mobile exchangeable positive ions; and similarly, the active basic functional groups attached to the associated organic polymer are oriented with respect to the interfaces thereof so as to be partially or completely dissociable in the internal gel water into fixed positive ions linked to the polymer and into mobile exchangeable negative ions.

Typical such polymers to which active acidic functional groups may be attached include: phenol-aldehyde resins, polystyrene-divinylbenzene copolymers, and the like; and such suitable active acidic functional groups include: @80 3, --COOH, and the like; -SO H being usually preferred because of its high dissociation constant.

Typical such polymers to which active basic functional groups may be attached include: urea-formaldehyde res ns, melamine-formaldehyde resins, polyalkylene-polyam ne-formaldehyde resins, and the like; and such suitable active basic functional groups include: quaternary ammonium hydroxides, amino groups, the guanidyl group, the dicyanodiamidine group, and like organic nitrogencontaining basic groups, the quaternary ammonium hydroxide groups, the guanidine and the dicyanodiamidine res due being usually preferred because of their high dissociation constants. Normally the water in gel relationship with the polymer should be present in an amount of at least 15% of the Weight of the dry resin.

As a constructional example of the unit 3t) especially designed for use in the dishwashing apparatus 10, the internal diameter of the cathode 31 may be 3%"; the inernal diameter of the barrier 33 may be 2%", the diameter of the anode 32 may be /8", the distance between the adjacent upper and lower surfaces of the plates 63 may be 6%; the other dimensions are proportionately gelated; and the volume of the bed 34 may be 0.02 cubic eet.

it is contemplated in the ordinary household that the dishwashing apparatus 10 will be utilized only once per day; and as explained more fully hereinafter, the water is conducted through the anode compartment 36 only during the final rinsing step in the automatic cycle thereof and involving a time interval of 30 seconds; whereby the flow control plug 97 may be constructed and arranged to accommodate the passage therethrough of 3 gallons per minute, thereby accommodating the passage of 6 quarts of anolyte through the anode chamber 36 of the unit 30 in each cycle of operation of the dishwashing apparatus 10. On the other hand, the flow of the catholyte through the cathode compartment 35 may be continuous and at the exceedingly low rate of about 12- gallons per month. In this case, the direct current may be conducted from the anode 32 to the cathode 31 con tinuously at about 0.1 amp. by impressing a direct voltage between the anode 32 and the cathode 31 of about 7- volts; whereby the energy requirement of the unit 3 may have an average value of about 0.5 kilowatt-hour per month, this value being somewhat variable and dependent upon the oharacter of the hard water being treated.

Turning now more particularly to the treatment of water in the unit 36, it is irst noted that ordinary hard water contains dissolved metal salts, particularly salts of alkali earth metals, which electrolytes include such cations as: Ca++, Mg Na' Fe++, etc., and such anions as: Cl, HCO CO 305*, N etc. Hard water to be treated frequently contains a dissolved solids count of 250 p. p. m. and higher, comprising dis.- solved electrolytes yielding the cations and the anions named; whereby it is totally unsuitable for use in the dishwashing apparatus for several reasons. In the first place, certain of these cations, particularly Ca++ form precipitates with ordinary detergents and also with many food soils introduced into the dishwasher on the dishes; whereby the resulting solids are deposited upon the dishes producing undesirable films, stains, etc. Moreover; incident to drying of the dishes, the evaporation reduce the total dissolved solids to a tolerable value. For example Chicago city water is only moderately hard containing about p. p. m. of hardness ions (calcu lated as CaCO and can be rendered altogether soft from a practical standpoint, by reducing the content of these hardness ions to 35 p. p. m; Restating the matter in terms of grains of hardness, Chicago city water is of 8 grains hardnessyw'nereby the volume of the ion exchange bed 34 has a capacity for softening 87.5 gallons of Chicago city water, since the volume of the bed 34 has an absolute capacity of reacting with 700 grains of water hardness. Now during the long time interval when no anolyte is conducted through the anode compartment 36, the continuous passage of the direct electric current between the anode 32 and the cathode 31 effects regeneration of the resins incorporated in the bed 34, and it may be readily calculated that this regeneration is at least 10% of that of the total capacity of the bed 34; whereby it is apparent that the unit 30 is regenerated to accommodate the softening of 8.75v gallons of Chicago city water per day. Now even if the dishwashing apparatus 16 were installed in an area having exceedingly hard water, such, for example, as a few areas having a water hardness as high as 25 grains, the regeneration capacity of the unit 34) is then reduced to only'2.9 gallons per day. However the conduction of even this volume of anolyte through the anode chamber 36 of the unit 34) is not required in the final rinsing step of the cycle of the dishwashing apparatus 10, as explained more fully hereinafter.

In the above discussion, only the demineralization or softening of hard water has been referred to, but it will be understood that the electrolysis that proceeds in the unit 39 is effective moderately to reduce the pH of the anolyte and substantially to increase the pH of the catholyte; whereby the reduction in the pH of the anolyte serves another very important function in die operation of the dishwashing apparatus 19 in that the rinse water involved in the final rinsing step of the automatic cycle thereof, being thoroughly acidified, is capable of dissolving previously deposited metal salts from the dishes undergoing the dishwashing operation, as it is apparent that the solubility of the metal salts is substantially increased as the pH of the final rinse solution is reduced with respect to neutrality. Thus this effect that is achieved in the dishwashing apparatus 10 is most beneficial in obtaining a satisfactory appearance of the dishes at the conclusion of the washing cycle.

The foregoing considerations will be understood in conjunction with a brief description of the electrodialysis that occurs in the unit 3K0. More particularly, the cations of the electrolytes dissolved in the anolyte are transported by diffusion through the permeable barrier 33 into the catholyte by virtue of the attraction between the positive electrical charges and the cathode 31; and conversely, the anions of the electrolytes dissolved in the catholyte are transported by difiusion through the permeable barrier into the anolyte by virtue of the attraction between the negative electrical charges and the anode 32. Thus the cations are preferentially extracted from the anolyte and accumulated in the catholyte, and the anions are preferentially extracted from the catholyte and accumulated in theanolyte. .Of course, the extracessence 9 tion of cations from the anolyte, as well as the accumulation of anions therein, efiects an increase in the hydrogen ion concentration in the anolyte; whereby the pH of this aqueous solution is correspondingly reduced and may be disposed within the range 4.0 to 5.0, in the operation of the unit 30; and conversely, the extraction of the anions from the catholyte, as well as the accumulation of cations therein, effects a decrease in the hydrogen ion concentration in the catholyte; whereby the pH of this aqueous solution is correspondingly increased and may be disposed within the range 9.0 to 10.0, in the operation of the unit 30. Of course, some oxygen is evolved at the anode 32 that is swept along with the anolyte into the vat 12 of the dishwashing apparatus while some hydrogen isevolved at the cathode 31 that is swept along with the catholyte into the trap 22 of the dishwashing apparatus 10.

During the conduction of the water through the bed 34 substantial amounts of the cations and the anions of the electrolytes dissolved in the raw water are respectively exchanged with hydrogen ions and hydroxyl ions respectively by the cation exchange resin particles and by the anion exchange resin particles, thereby correspondingly depleting respectively the cation exchange capacity of the cation exchange resin particles and the anion exchange capacity of the anion exchange resin particles. However, when the valve in the supply pipe communicating with the anode compartment 36 is subsequently closed, the cation exchange resin particles and the anion exchange resin particles undergo partial regeneration, since the conduction of the direct current from the anode 32 to the cathode 31 is continuous. Specifically, the cation exchange resin particles are regenerated by the release of the cations of the previously exchanged metal salts and by the recapture of hydrogen ions from the anolyte, which cations diffuse through the permeable barrier 33 into the continuously flowing catholyte and are transported to the exterior of the unit 30, as previously explained. Similarly, the anion exchange resin particles are regenerated by the release of the anions of the previously exchanged metal salts and by the recapture of hydroxyl ions from the anolyte, which anions accumulate in the anolyte with the ultimate formation of oxygen molecules dispersed therethrough.

The arrangement of the mixed resin bed 34 in the anode chamber 36 is very advantageous as it materially reduces the internal resistance of the unit 30 between the anode 32 and the cathode 31 greatly facilitating the migration of both the cations and the anions through the permeable barrier 33, whereby the heating of the anolyte .and'the catholyte passing through the unit 30 is greatly minimized, thereby drastically reducing the energy requirements thereof. Although the phenomenon is not altogether understood, it is surmised that the resins in the mixed resin bed 34 constitute solid poly-electrolytes for the transportation of the ions, and specifically, it is visualized that the cations are involved in a great multiplicity of exchanges with a considerable number of the individual cation exchange particles in their migration toward the cathode 31, and that the anions are involved in a great multiplicity of exchanges with a considerable number of the individual anion exchange particles in their migration toward the anode 32; the mechanism involved being visualized as like the mode employed in .playing the childs game of musical chairs. In this .same given number of ions through the same distance in the anolyte or in the catholyte, due fundamentally .tothe fact that in the direct migration of the ions there .must be a great amount of energy lostthrough random ,collision by the ionswith water moleculesand the:ions

must expend a great amount of work upon these dipolar molecules in passing therethrough. 'In'anycase, and without reference to the exact mechanism involved, the utilization of the mixed resin bed 34 in the anode chamber 36 drastically reduces the energy requirements of the unit 30 with respect to the requirements thereof in the absence of the mixed resin bed 34 to effect the same total ion exchange. Moreover, the provision of the mixed resin bed 234 permits a substantial reduction ,in the size-of the unit 3021s it in effect permits of the accumulation or storage-of ion exchangecapacity during-the extremely long time interval during which the anolyte is not actively conducted through the anode compartment 36. this connection, it is noted that the continuous conduction of the catholyte'through the cathode chamber T35 is very important as the arrangement insures that the'ione'xchange bed 34 remains we: .at all times and in readiness to efiect the required ion exchange when the anolyte is conducted through the anode chamber 36 during the short time interval, as it will 'be :recalled that in these polymeric ionexcnange resins water vmust be maintained in gel relationship with respect thereto, as the ion exchange mechanism thereof involves the utilization of this water in rg'elrela'tionship therewith. In other words, it is important that the ion exchange bed 34 be flooded with'water at all times so that it is in readiness to performthe required ion exchange function .at all times.

Recapitulating, in conjunction with the operation of the unit '30, the raw Chicago city water in the inletpipe 14 may contain 8 grains of hardness and have apHof 7.0; whereas the anolyte that is conducted through-the anode compartment 36 and employed in the final-rinsing step of the automatic cycle of the dishwashin'g apparatus 10 may contain about '2 grains of hardness -and have a pH within the approximate range 4.0-to 5.0.

The construction and arrangement of'the unit30, as well as the method of treating hard water therein, described above, is disclosed and claimed in the copendin'g divisional application of Edgar S. Stoddard, Serial No. 556,196, filed December 29, 1955.

Referring now to Fig. 5, the control circuit for the apparatus 1-0 comprises the previously mentioned elements 19, 20a, 21a, 30, 31, 32,4701, 50, 51, 52, 53,54, 55 and R56, as well as the alternating current source of supply that is provided with a grounded lineco'nductor 101 and an ungrounded line conductor 102. The program controller 51 includes a rotatably mounted operating shaft 103, carrying five insulating control cams C1, C2, C3, C4 and C5 respectively cooperating with fiv'e sets of switch springs S1, S2, S3, S4 and S5, as well as a timer motor 104 of the synchronous type "and provided with a drive shaft 105, and escapement mechanism 106. The drive shaft drives the esc'apement mechanism 106; and the escapement mechanism 106 drives the inner end of the operating shaft 103, the extreme outeren'd of the operating shaft 103 carrying the manual control dial 52, as previously mentioned. In the arrangement, when the timer motor 104 is energized, the drive shaft 105 is rotated at a synchronous speed of 3600 R1. M'., and the escapement mechanism 106 incorporates speedreduction gearing, as well as escapement mechanism proper; whereby the operating shaft 103 is rotated intermittently in the clockwise direction in steps of 3 each every 30-seconds. Also, the escapement mechanism 106 accommodates rotation of the operating shaft 103 in the clockwise direction under the control of the manual control dial 52 independently of the timer motor 104; whereby the manual control dial 52 is manually rotated from its off position into its on position and is then rotated step-by-step back into its off position by the escape merit mechanism 306, as explained more fully hereinafter.

In the program controller 51, the control cam springs S5, the contacts are closed. -cuit 100, the line conductors 101 and 102 are respecas e ses comprises three control levels, and the set of switch springs S1 comprises three individual springs, the rightbetween the middle spring and the left-hand spring. Similarly, the control cam C2 comprises three control levels, and the set of switch springs S2 comprises three individual springs, th middle spring riding the control cam C2; whereby the control cam C2 selectively controls 1 contacts between the right-hand spring and the middie spring and 2 contacts between the middle spring and the left-hand spring. Similarly, the control cam C3 comprises three control levels, and the set of switch springs S3 comprises three individual springs, the middle spring riding the control cam C3; whereby the control cam C3 selectively controls 1 contacts between the right-hand spring and the middle spring and 2 contacts between the middle spring and the left-hand spring. Similarly, the control cam C4 comprises three control levels, and the set of switch springs S3 comprises three individual springs, the middle spring riding the control cam C4; whereby the control cam C4 selectively controls 1 contacts between the right-hand spring and the middle spring and 2 contacts between the middle spring and the left-hand spring. Similarly, the control cam C5 comprises two control levels,.and the set of switch springs S5 comprises two individual springs, the left-hand spring riding the control cam C5; whereby the control cam C5 selectively controls contacts between the two springs. When the program controller 51 occupies its oft position: in the set of switch springs SL'the contacts X and the contacts Y are open; in

the set of switch springs S2, the contacts 1 and the A contacts "2 are open; in the set of switch springs S3, the contacts 1 are closed and the contacts 2 are open;

in the set of switch springs S4, the contacts 1 are closed and the contacts 2 are open; and in the set of switch In the control cirtively connected to two movable blades of the control switch 54 which two blades are provided with two stationary contacts that are connected by two conductors "121 and 122 to the input terminals of the rectifier unit -55, the output terminals of the rectifier unit 55 being connected by two conductors 123 and 124 respectively to the cathode 31 and to the anode 32. In the arrangement, the rectifier unit 55 may be of any conventional type; whereby the input voltage of 118-volts A. C. is converted into an output voltage of about 10-volts D. C., the positive terminal being ungrounded and connected to the anode 32 and the negative terminal being grounded and connected to the cathode 31; the line conductor 102 is connected to one spring of the door switch 53 and the other spring of the door switch 53 is connected to a supply conductor 107.- The terminals of the drive motor 19 are connected across the supply conductor 107 and a conductor 108; the terminals of the relay R56 are connected across the conductor 108 and a conductor 109; the terminals of the heating unit 50 are connected across two conductors 110 and 111; the terminals of the timer motor 104 are connected across the supply conductor 107 and the conductor 111; the terminals of the main inlet valve solenoid 20a are connected across two conductors 112 and 113; the terminals of the auxiliary inlet valve solenoid 47a are connected across the conductor 112 and a conductor 114; and the terminals of the drain solenoid 21a are connected across the conductor 112 and a conductor 115; the relay R56 is pro- :vided with a pair of normally closed switch springs 116 and 117 respectively terminating two conductors 118 and 119. In the set of switch springs S1, the right-hand spring, the middle spring and the left-hand spring respectively terminate the conductor 111, the line conductor 101 and the conductor 109; in the set of'switch 12 springs S2, the right-hand spring, the middle spring and the-left-hand spring respectively terminate the conductor 112, the supply conductor 107 and the conductor in the set of switch springs S3, the right-hand spring, the middle spring and the left-hand spring respectively terminate the conductors 108, 109 and 118; in the set 'ot switch springs S4, the right-hand spring, the middle spring and the left-hand spring respectively terminate the conductors 113, 119 and 114; and in the set of switch springs S5, the right-hand spring and the left-hand spring respectively terminate the conductors and 109.

Considering now the cycle of operation of the dishwashing apparatus 10, the person loads the dishes, glassware and other objects to be washed into the rack structhe supply conductor 107. Preferably, the detergent that is employed is of the type sold under the tradename Calgonite that comprises about 40% sodium hexametaphosphate and 60% sodium metasilicate. In the detergent the sodium hexarnetaphosphate is particularly effective to sequester calcium and magnesium cations, thereby minimizing the precipitation of solids from the hot water subsequently introduced into the vat 12. The manual control dial 52 is then rotated from its 011 position into its on position, whereby the control cams C1,

.C2 and C5 operate the associated sets of switchsprings .S1, S2 and 55, as indicated in the chart of Fig. 6. Specifically, the control cam C1 closes the X contacts and the Y contacts of the set of switch springs S1; the control cam C2 closes the 1 contacts of the set of switch springs S2; and the control cam C5 opens the contacts of the set of switch springs S5. Closure of the contacts X of the set of switch springs S1 completes a circuit, including the, conductor 111 for operating the timer motor 104 across the line conductor 101 and the supply conductor 107. The closure of the Y" contacts of the set of switch springs S1 completes a circuit, including the conductor 109, the 1 contacts of the set of switch springs S3 and the conductor 108, for operating the drive motor 19 across the line conductor 101 and the supply conductor 107. The normally closed 1 contacts of the set of switch springs S3 maintains a shortcircuit, including the conductors 108 and 109, around the winding of the relay R56 so as to prevent the starting current of the drive motor 19 from traversing the Winding mentioned at this time; opening of the contacts of the set of switch springs S5 positively insures that the drain valve solenoid 21a is deenergized so that the drain valve 21 occupies its open position at this time. The operating drive motor 19 rotates the impeller 18; however, without efi'ect at this time. The operating timer motort104 operates the escapement mechanism 106 on a timed control basis; whereby the operating shaft 103 of the program controller'51 is rotated step-by-step further in the clockwise direction and ultimately back into its ofi position'bringing the manual control dial 52 back .into its off position, Specifically, the operating shaft 103 is rotated 3 each 30-seconds, as previously exof switch springs S3 removes the previously-mentioned assaeea short-circuit from around the winding of the relay R56; whereby a series circuit is completed, including the contacts Y of the set of switch springs S1 and the condoctors 1139 and 19$, for energizing the winding of the relay R56 and the drive motor 19, so that operation of the drive motor 19 continues, but the relay R56 is not operated, as it is of the marginal type, and since the current traversing the drive motor 19 is exceedingly small at this time. Closure of the contacts 2 of the set of witch springs S3 completes a circuit, including the contacts Y of the set of switch springs S1, the conductor 109, the conductor 118, the switch springs 116 and 117 of the relay R56, the conductor 119, the contacts 1 of the set of switch springs S-l, the conductor 113, the condoctors 112 and the contacts 1 of the set of switch springs S2, for energizing the main inlet valve solenoid 21 across the line conductor 101 and the supply conductor 107; whereby the main inlet valve 20 is operated into its open position at this time, bringing about the supply of hot water from the inlet conduit 14 to the water inlet mechanism 16 and the resulting downward spray thereof through the supported dishes. The hot water thus sprayed downwardly through the supported dishes in the vat 12 is accumulated in the sump 17 and passes through the drain valve 21 in its open position into the drain conduit whereby the supported dishes are subjected to an initial spray-step with hot water.

At the expiration of an additional step of the escapement mechanism 106, the operating shaft 103 is rotated from its spray section into its first wash section of its on position as indicated in the chart of Fig. 6; whereby the control cam C5 operates the set of switch springs S5 to effect closure of the contacts thereof so as to complete a circuit, including the Y contacts of the set of switch springs S1 and the conductors 109, 115 and 112, and the 1 contacts of the set of switch springs S2, for energizing the drain valve solenoid 21a across the line coucluctor 101 and the supply conductor 107. Accordingly, the drain valve 21 is operated into its closed position so that the remainder of the hot Water introduced into the vat 12 is accumulated therein and is caught-up by the impeller 18 and circulated upwardly through the supported dishes effecting a first washing step in the automatic cycle of the apparatus 10. Upon the accumulationv of a predetermined amount of wash water in the sump 17, it is deflected by the impeller 18 into the detergent cup 13a efiecting the washing of the charge of detergent previously mentioned, into the charge of wash water for the washing purpose.

As the amount of water accumulating in the sump 17' increases, the load imposed upon the impeller 13 and. consequently upon the electric motor 19 increases with the result that a larger current traverses the winding of the relay R56; whereby upon the accumulation of a pre-- determined charge of wash water in the sump 17, a pre determined load is imposed upon the electric motor 19 so that a predetermined current traverses the winding: of the relay R56 effecting operation thereof, this relay being of the marginal type. Upon operating, the relay R56 interrupts the contacts between the springs 116 and. 117 etiecting the deenergization of the main inlet valve solenoid 2th; with the result that the main inlet valve 20* is returned back into its closed postion, so that the first. washing step proceeds in the vat 12 without the further addition of hot Water. After two additional steps of the escapement mechanism 106, the operating shaft 103 is rotated so that the control cam S3 erlects operation of the set of switch springs S3 opening the contacts 2 and closing the contacts 1 thereof, as indicated in the chart of Fig. 6. Opening of the contacts 2 of the set of switch springs S3 interrupts a further point in the pre-- viously traced circuit for energizing the main inlet valve solenoid 213:: so that in any case the main inlet valve 20 is returned back into its closed position and regardless of whether the relay R56 has operated in the manner 14 previously explained. .Closure of thecontacts "1 of the set of switch springs S3arecompletes the previously traced path for short-circuiting the winding of the relay 1156, thereby to insure thatthe relay R56 is in its restored position, the relay R56 being restored in th event it was previously operated, as previously explained. Moreover, the completion of the above-traced path for short-circuiting the winding of the relay R56 completes the previously traced original circuit for operating the drive motor 19 independently of the winding of the relay The first washing step in the automatic cycle of the apparatus 10 continues and at the conclusion offive additional steps of the escapement mechanism 106, the operating shaft 103 is rotated into its first drain posias indicated in the chart of Fig. 6, whereby the control cam C5 operates the set of switchsprings S5 to open the contacts thereof effecting the deenergization of the drain valve solenoid 21a so that the drain valve 21 is returned into its open position with the result that the first charge of wash water is drained from the vat 12 into the drain conduit 15 and thence into the drain plumbing, not shown.

The automatic cycle of the apparatus 10 includes a second washing step that is similar to the first washing step described, except that the preliminary spray of the supported dishes is eliminated, as shown in the chart of Fig. 6; and also the automatic cycle includes a first rinsing step that is essentially the same as that of the first washing step described above, except that the time duration thereof corresponds to only threesteps of the escapement mechanism 106.

At the conclusion of draining following the first rinsing step of the apparatus 10, the operating shaft 103 is rotated into its flush section, whereby the control cam C4 operates the set of switch springs S4, as indicated in the chart of Fig. 6. Spechically, the contacts 1 of the set of switch springs S4 are opened in order to interrupt a point in the previously traced circuit for energizing the main inlet valve solenoid 20a, and the contacts 2 of the set of switch springs S4 are closed in order to complete a circuit for energizing the auxiliary inlet valve solenoid 47a across the line conductor 101 and the supply conductor 107. This circuit includes the contacts Y of the set of switch springs S1, the conductor 109, the contacts 2 of the set of switch springs S3, the conductor 118, the switch springs 116 and 117 of the relay R56, the conductors 119, 114 and 112, and the contacts 1 of the set of switch springs S2. Accordingly, the auxiliary inlet valve 47 is operated into its open position with the result that the hot-hard water from the inlet conduit 14 is conducted into the anode chamber 36 of the unit 13, displacing the anolyte therefrom and via the conduit 48 into the vat 12, while the drain valve 21 occupies'its open position. Accordingly, the aqueous solution comprising the anolyte of the unit 30 is introduced into the vat 12 and flushed therethrough into the drain conduit 15. At the conclusion of one additional step of the escapement mechanism 106, the operating shaft 103 is rotated into its second rinse section, whereby the control cam C5 operates the set of switch springs S5, as indicated in the chart of Fig. 6. Specifically, the contacts of the set of switch springs are closed re-completing the circuit for energizing the drain valve solenoid 21a so that the drain valve 21 is operated into its closed position. Accordingly, the remainder of the aqueous solution comprising the anolyte of the unit 30 that is introduced into the vat 12 is retained therein, this rinse solution being utilized in the second rinsing step of the apparatus 10. At the conclusion of one additional step of the escapement mechanism 106, the operating shaft 103 is rotated so that the control cam C4 efiects operation of the set of switch springs S4, whereby the circuit for energizing the auxiliary inlet valve solenoid 47a is interrupted with the result that the auxiliary valve 47 is r Y 15 returned back into its closed position arresting the supply of the anolyte from the unit 30 into the vat 12.

In view of the above, it will be understood that the anolyte from the unit 30 is flushed through the vat 12 for a time interval corresponding to one step of the escapement mechanism 106 and is then caught in the vat 12 for a time interval corresponding to one additional step of the escapement mechanism 106; and that the rinsing of the dishes with this second rinse solution proceeds for a total time interval corresponding to three steps of the escapement mechanism 196; whereupon the operating shaftlttS is rotated so that the control cam C operates the set of switch springs S5 to open the contacts therebetween so as to interrupt the circuit for energizing the drain valve solenoid 21a with the result that the drain valve 21 is returned back into its open position to accommodate draining of the second rinse solution from the sump 17, as illustrated in the chart of Fig. 6.

This arrangement insures that the initial portion of the anolyte in the anode chamber 36 of the unit 39, which is perhaps cold or only tepid, is flushed through the vat 12 preceding the second rinsing operation. Of course, the initial portion of the anolyte mentioned is quickly flushed through the anode chamber 36 of the unit 30, when the auxiliary inlet valve 47 is operated into its open position, and is replaced by hot raw Water from the inlet conduit 1-4. This hot raw water is immediately treated by virtue of the storage capacity of the bed 34, as previously explained, and then supplied to the vat 12 to provide the second rinse solution in the second rinsing step of the apparatus 111, in the manner previously explained, thereby insuring that the second rinse solution is, in fact, a hot solution.

At the conclusion of one additional step of the escape- .ment mechanism 106, the operating shaft 103 is rotated so that the control cam C2 operates the set of switch springs S2 to efiect opening of the contacts 1 and closing of the contacts 2 thereof. Opening of the contacts 1 of the set of switch springs S2 interrupts the connection to the conductor 112, thereby positively preventing further energization of the solenoids 2811,2112 and 47a; while closure of the contacts 2 of the set of switch springs S2 completes a circuit, including the contacts Y of the set of switch springs S1 and the conductors 111 and 118, for energizing the heating unit 5 across the line conductor 191 and'the supply conductor 12?. Thus at this time, the heating unit 58 is heated and impeller 18 effects the circulation of a current of hot air through the vat 12 and through the supported dishes to effect tying thereof. This drying step continues for thirtyeight steps of the escapem ent mechanism 1%; whereby the operating shaft 103 is rotated so that the control cam C1 operates the set of switch springs S1 to open the Y contacts thereof, without opening the'X contacts thereof. This selective opening of the contacts Y of the set of switch springs S1 interrupts the previously traced circuit for operating the drive motor 19 with the result that rotation of the impeller 18 is arrested, with continued energization of the heating unit Sill and continued opera-f tion of the timer motor 184 and the escapement mechanism 106, as illustrated in the chart of Fig. 6. p

More particularly, at the conclusion of eighteen additional steps of the escapement mechanism 1%, the operating shaft 103 is returned back into its 011 position returning the manual control dial 52 back to its oi'f posi tion; whereby the control cam C1 operates the set of switch springs S1 so as to open the contacts X thereof, while retaining open the contacts Y thereof. The control cam C2 operates the set of switch springs S2 to open the contacts 2 thereof, while retaining open the contacts 1 thereof. Opening of the contacts X of the set of switch springs S1 interrupts both the circuit for energizingthe heating unit 50 and the circuit for operating the timer motor 1%; whereby the automatic cycle of the apparatus is completed at this time. Of course, drying vat 12 through the unit 359.

V a a 16 of, the supported dishes in the vat 12 continues by virtue of the fact that both the dishes and the interior of the vat 12 are hot at this time. However, the dishes are substantially dry at this time, and they maybe removed after opening the front door 13, if desired.

Recapitulating, from an examination of the chart of Fig. 6, itwill be appreciated that in' the automatic cycle of the apparatus 10, the supported dishes are first subjected to a sprayingstep of 30-seconds; then the supported dishes are subjected to a first washing step of 3-minutes and SD-secondsythen after 1-minute, the supported dishes are subjected to a second washing step of 3-minutes and 30-seconds; then after l-minute, the supported dishes are subjected to a first rinsing step of 1-minute and 30-seconds; then after 1-minute, the supported dishes are subjected to a flushing step of 30-seconds; then the supported dishes are subjected to a second rinsing step of 1-minute and 30-second's; then after 1-minute, the supported dishes are subjected to a preliminary drying action by heating, with the circulation of a current of fair, of l9-minutes; and then the supported dishes are subjected to a secondary drying action by heating, without the circulation of a current of air, of 9-minutes. 1n the spray step, in the first washing step, in the second Washing step and in the first rinsing step, raw hard hot water is employed in the vat 12, since the supply of solution thereto is governed by the main inlet-valve in controlling the direct connection from the inlet conduit 1-to the vat 12, and bypassing the unit 30. On the other hand, in the flushing step and in the final rinsing step, the anolyte of the unit 30 is employed in the vat 12, since the supply of solution thereto is governedby the amnliary inlet valve 47 controlling the connection from the inlet conduit 14 to the This arrangement, wherein the unit 50 is employed only to supply treated water to the vat 12 in the second or final rinsing step thereof, is very advantageous, as the utilization of such treated water is really only required in the final rinsing step immedi ately preceding the dryingrstep; whereby the water-treating capacity of the unit 30 may be greatly minimized with the consequent economy with respect to size and manufacturing costs thereof.

Moreover, the supply of this particular anolyte from the unit 30 to the vat 12 for the carrying out of the final rinsing action comprises an important feature of the method and of the apparatus, as the composition thereof is unique, since the normal operation of the unit 30 not only effects softening of the hard water (with respect to the removal of the cations of the metal salts therefrom) but it also eflects acidification thereof with the result that the final rinse solution is both soft and acidified. The soft character of the final rinse solution prevents the deposit of metal'salts upon the dishes in the subsequent drying step, Whereas the acidic character of the final rinse solution efiects the substantial dissolving of any prior deposits of metal salts upon the dishes, as well as dissolving of other types of deposits and films from the dishes; wherebythe general appearance of the dishes is materially improved with respect to that produced in conventional dishwashing apparatus. This general improvement in the appearance of the dishes is particularly noticeable in the additional sparkle that is imparted to glassware and the higher degree of luster imparted to fsilverware.

Furthermore, the supply of this particular catholyte fromthe unit 30 into the trap structure 22 comprises an important feature of the method and of the apparatus, as the composition thereof is unique, since the normal operation of the unitfill not only concentrates calcium, 7

higher fatty acids of animal and'veget-able origin that tend to collect and cake in the trap structure 22, and otherwise render water-soluble many other organic compounds that tend to encrust the interior surfaces of the trap structure 22. Thus, the arrangement renders the trap structure 22 self-cleaning, and contributes materially to the satisfactory operation of the apparatus 1% over a long period of time, without special care or attention.

Again considering the automatic cycle or" the apparatus ill, it may be assumed that the hot raw Water that is supplied to the inlet conduit 14 has a temperature in the general range 135 F. to 150 F. and a pressure of about p. s. i.; that the main inlet valve 2t; in open position accommodates the supply of the hot raw Water to the water inlet fixture 16 at a rate of about IZ-ouarts per minutes; that the flow control plug 97 incorporated in the unit 3%; accommodates the supply of the hot raw water to the anode chamber 36 when the auxiliary inlet valve d7 occupies its open position at a rate of about lZ-quarts per minute, and that the manual vlave 43 is adjusted to effect the continuous supply of the hot raw water to the cathode chamber 35 at at rate of about lZ-gallons per month. Moreover, the marginal characteristic of the relay R56 is adjusted so that it is operated when the load imposed upon the drive motor 19 is that corresponding to a load imposed upon the impeller 1% by the accumulation in the sump 17 of about 15'; uarts of water. Thus, in the automatic cycle of the apparatus 10: in the spray step about -quarts of hot raw water are sprayed downwardly through the supported dishes and discharge from the sump 17 to the exterior; in the first washing step about 6-quarts of hot raw water are accumulated in the sump 17 under the control of the relay R56 and circulated by the impeller 18 for the first washing purpose; and likewise, in the second Washing step and in the first rinsing step, about -quarts of hot raw water are accumulated in the sump 17 under the control of the relay use and circulated by the impeller 18 for the second washing purpose and for the first rinsing purpose.

In the flushing step about S-quarts of treated solution from the unit 3% are flushed through the vat l2; and in the second rinsing step about 6 quarts of hot treated solution from the unit 39 are accumulated in the sump 17 under the control of the relay R56 and circulated by the impeller 18 for the second rinsing purpose. in the flushing step and in the second rinsing cycle step, it is noted that while the auxiliary inlet valve 47 occupies its open position for a total time interval of 1-minute, the flow through the anode chamber 36 of the unit is also established by the flow control plug 97 at the rate of 3-gallons or lZ-quarts per minute.

Also, in this regard, it is recapitulated that both the total quantities and flow rates of the raw water through the respective cathode chamber and anode chamber 36 are altogether disproportional in the normal operation of the unit 30 in the dishwashing apparatus 10. Specifically, the catholyte is conducted continuously through the cathode chamber 35 in a total quantity of about 12- gallons in a period of one month or thirty days; whereas the anolyte is conducted intermittently through the anode chamber 36 about once per day or thirty times per month and in the total quantity of about 9G-gallons in the period of one month or thirty days. Thus the conduction of the catholyte through the cathode chamber 35 is at a rate of about 2.8 l0- gallons per minute, While the conduction of the anolyte through the anode chamber 36 is at a rate of about 3.0 gallons per minute; whereby the rate of flow of the anolyte through the anode chamber 36 is about 10,090 times as great as that of the rate of flow of the catholyte through the cathode chamber 36. However, the arrangement is entirely feasible, since the how of the anolyte at its relatively high rate through the anode chamber 36 occurs only for about 1-minute. in each twenty-four hour period; Whereas the of the cathoiyte at its exceedingly low rate through the cathode chamber 35 occurs continuously; the ion exchange bed 34 has a high rate of expenditure of its accumulated capacity to exchange ions; and the ion exchange bed 34 is under continuous regeneration at the low rate involving the continuous conduction thereof of the direct electric current of about 9.1 amp.

In a modification of the control circuit 180, the control cams C2, C3, C4 and C5 are varied slightly in order to increase the time intervals of the first and second washing step" rn 3-minutes and BO-seconds to S-minutes and 3G-secon and to increase the time intervals of the first and second rinsing steps from 1-minute and 30-seconds to Z-minutes and 3G-seconds; which modification requires no illustration, since it amounts to a mere extension of the corresponding time intervals in the chart of Fig. 6.

Referring now to Fig. 7 of the drawings, the modified form of the dishwash ng apparatus 10 there illustrated is essentially the same as that of the apparatus 10 except that an electric water heater 260 is incorporated therein and arranged in the conduit extending from the unit 230 to the vat 212. Specifically, the electric water heater 260 comprises a tank 261, the inlet or bottom of which is connected to the conduit section 248a and the outlet or top of which is connected to the conduit section 248]). The other ends of the conduit sections 248a and 248b are respectively connected to the anode chamber of the unit 236 and to the vat 212 in the manner previously explained, whereby the electric Water heater 260 is merely inserted in the conduit 245. The tank 260 is provided with an insulating jacket, indicated at 262, as well as an electric heating element 253 and a thermostatic switch 264-. The electric heating element 263 may be of the conventional immersion type arranged in the bottom of the tank in; and the thermostatic switch 264 may be of any conventional type and arranged in the wall of the tank 261 intermediate the bottom and the top thereof; the elements 263 and 26 being connected in series relation and across the alternating current source of power supply in a conventional manner. In the arrangement, the tank Ital may have a volume of about Z-gallons and the thermostatic switch 264 may be set to govern the circuit of the electric heating element 263 so as to maintain a temperature of about F. of the treated anolyte contained in the tank 261.

it is contemplated that the electric water heater 260 will be arranged within the cabinet, not shown, of the apparatus 21% eXteriorly of the vat 212 and preferably adjacent to the water-treatment unit 230 so as to provide a compact arrangement of the elements. Also, in the apparatus 21%), it is pointed out that the supply of raw water via the conduit 246 into the anode chamber of the unit 239, when the auxiliary inlet valve 247 occupies its open position, as well as the supply of raw water via the conduit 242 into the cathode chamber of the unit 230; when the manual valve 243 occupies its open position, is efiected from an associated inlet conduit 25% that may be connected either to a hot source of raw water under pressure or to a cold source of raw water under pressure, as desired. In other Words, it is not essential that hot raw water be supplied to the unit 239, since the electric water heater Zoo is provided; whereby the conduit 250 may be connected to a cold water supply conduit, if convenient, or to the hot water inlet conduit 214.

Considering now the mode of operation of the apparatus 21b and assuming that the inlet conduit 250 is connected to a source or" cold raw water under pressure, the manual valve 2% is opened to provide the continuous supply of catholyte through the cathode chamber of the unit 23%), the catholyte draining into the trap structure 222 for the purpose previously explained. Now when the auxiliary inlet valve 247 is operated into its open position, the cold raw water from the inlet conduit 250 is conducted through the anode chamber of the unit 230 for the treatment purpose previously explained and the retemperature of about 160 R,

sulting anolyte is conducted via the conduit section 248a into the bottomof the tank 261. The cold anolyte suppliedinto' the bottom of the tank 261 drives the hot anolyte therein through the conduit section 248]) into the vat 212 and governs the thermostatic switch 264 to bring about energization of the electric heating element 253 so that the auolyte in the tank 261 is again heated to the as previously mentioned. In this arrangement, since the treated anolyte in the tank 269 is at the required temperature for the final rinsing purpose in the vat 212, there is no occasion to flush any portion thereof through the vat 212; whereby the control circuit 1% when employed in the apparatus 210 is I, preferably modified to eliminate the flushing step immeditaneously with the closure of the set of switch springs S5 by the control cam C5; whereby the auxiliary inlet valve 247 is energized for a total time duration corresponding to only one step of the escapement mechanism use. This arrangement i very advantageous in view of the fact that none of the anolyte from the unit 23% is wasted by flushing through the vat 212 preceding the final rinsing step, by virtue'of the fact that the anolyte that is supplied to the vat 212 is always hot as a result of the provision of the electric water heater 266' in the conduit 248 and interposed with respect to the unit 23% and the vat 212; whereby the water-treatment capacity of the unit 23% may be substantially reduced. Furthermore, since the tank 261 has a capacity of about Z-gallons and only about -quarts of the anolyte is employed in the final rinsing step of the apparatus 210 in a 24-hour period, in the normal operation thereof, thereis no recovery problem in the electric Water fication of the electric control circuit 19% described above has not been illustrated; all in the interest of brevity, since these items are readily apparent from the complete description and illustration of the apparatus ill and the electric control circuit 31%.

In the construction of the apparatus it) and 21% the materialsof the component element thereof should be selected in view of the pH of the corresponding aqueous solutions in contact therewith, stainless steel being generally recommended, as it must be borne in mind that many materials that are resistant to corrosion in acid solutions are not necessarily resistant to corrosion in basic solutions, and conversely.

In the foregoing specification and in the appended claims the terminology dishes is employed, but it will be appreciated that this terminology is employed in the broad sense to embrace the ordinary items that are normally washed in home dishwashing apparatus; whereby the term dishes embraces items formed of porcelain, pottery, glass, metal, bone, plastics, wood, etc., which items are employed in the storage, preparation, cooking, serving and eating of foods and drinks.

In view of the foregoing, it is apparent that there has been provided an improved method of and apparatus for washing dishes, or the like, and incorporating apparatus for treating water-employed in such dishwashing apparatus.

Vhile there has been described what is at present considered to be the preferred embodiment of the invention,

7 2t it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

. The method of washing dishes comprising providalts, producing a wash solution from a first porsaid raw water by dissolving therein'a quantity c subjecting the dishes to a washing action 1 solution, producing a rinse solution from a second portion of said raw Water by preferentially extracting therefrom the cations with respect to the anions of said dissolved metal salts with the consequent simultan ous reduction of the concentration of said cations therein and of the pH thereof, and then subjecting the dishes to a rinsing action with said rinse solution.

2. The method set forth in claim 1, wherein said preferential extraction of said cations with respect to said anions is controlled to effect the reduction of the pH of said second portion of said raw Water to a value within the approximate range 4.0 to 5.9.

3. The method of washing dishes comprising providing raw water having dissolved therein small amounts of metal salts, producing a wash solution from a first portion of said raw water by dissolving therein a quantity of detergent, subjecting the dishes to a washing action with said wash solution, producing a rinse solution from a second portionof said raw water by preferentially extracting therefrom the cations with respect to the anions of said dissolved metal salts with the consequent simultaneous reduction of the concentration of said cations therein and of the pl-l thereof, subjecting the dishes to arinsing action with said rinse solution, and then subjecting the dishes to a drying action by a current of hot air.

The method of washing dishes comprising provi ing raw water having dissolved therein small amounts of salts of an alkali earth metal selected from the class consisting of calcium and magnesium, producing a wash solution from a first portion of said raw water by dissolving therein a quantity of detergent, subjecting the dishes to a washing action with said wash solution, producing a rinse solution from a second portion of said raw water by preferentially extracting therefrom the cations with respect to the anions of said dissolved alkali earth metal salts with the consequent simultaneous reduction of the concentration of said cations therein and of the pH thereof, and then subjecting the dishes to a rinsing action with said rinse solution.

5. The method set forth in claim 4, wherein said alkali earth metal salts are selected from the group consisting f chloride, sulfate, carbonate and bicarbonate.

6. The method of washing dishes comprising providing raw water having dissolved therein small amounts of metal salts, producing a wash solution from. a first portion of said raw water by dissolving therein a quantity of detergent, subjecting the dishes to awashing action with said wash solution, producing a rinse solution from a second portion of said raw water by extracting therefrom a substantial proportion of the cations of said dissolved metal salts without extracting therefrom any substantial proportion of the anions of said dissolved metal salts with the consequent simultaneous reduction of the concentration of said cations therein and of the pH thereof, and then subjecting the dishes to a rinsing action with said rinse solution.

7. The method of washing dishes comprising providing raw water having dissolved therein small amounts of metal salts, producing a wash solution from a first portion of said raw water by dissolving therein a quantity of detergent, subjecting the dishes to a Washing action with said wash solution, extracting from a second portion of said raw water some of the cations of said dissolved-metal salts therein, extracting from a third portion of said raw water some of the anions of said dissolved metal salts therein and transporting said extracted anions into said second portion of said raw water to produce a rinse solution therefrom, and then subjecting the dishes to a rinsing action With said rinse solution.

8. The method of Washing dishes comprising providing raw Water having dissolved therein small amounts of metal salts, producing a Wash solution from a first portion of said raw Water by dissolving therein both a quantity of a detergent and a quantity of a metal cation sequestering agent, subjecting the dishes to a washing action With said Wash solution, producing a rinse solution from a second portion of said raw water by preferentially extracting therefrom the cations with respect to the anions of said dissolved metal salts with the consequent simultaneous reduction of the concentration of said cations therein and of the pH thereof, and then subjecting the dishes to a rinsing action with said rinse solution.

9. The method of Washing dishes comprising providing raw water having dissolved therein small amounts of metal salts, producing a hot wash solution from a first portion of said raw Water by heating the same and by dissolving therein a quantity of detergent, subjecting the dishes to a washing action with said hot Wash solution, producing a hot rinse solution from a second portion of said raw Water by heating the same and by preferentially extracting therefrom the cations with respect to the anions of said dissolved metal salts with the consequent simultaneous reduction of the concentration of said cations therein and of the pH thereof, and then subjecting the dishes to a rinsing action with said hot rinse solution.

10. The method set forth in claim 9, wherein said second portion of said raw Water is heated prior to the extraction therefrom of the ions of said dissolved metal salts.

11. The method set forth in claim 9, wherein said second portion of said raw water is heated subsequent to the extraction therefrom of the ions of said dissolved metal salts.

12. The method of Washing dishes comprising providing hot raw water having dissolved therein small amounts of metal salts, introducing a quantity of detergent into a first portion of said hot raw Water to produce a hot wash solution, subjecting the dishes to a washing action with said hot Wash solution, conducting second and third portions of said hot raw Water into cooperating relation With'the opposite sides of a diaphragm and simultaneously conducting an electric current therehetween and through said diaphragm so that said second and third portions of said hot raw Water respectively constitute a hot catholyte and a hot anolyte with the result that the anions and the cations of the dissolved metal salts therein are respec 'vely concentrated in said hot anolyte and in said hot catholyte efiecting simultaneous alkalizing of said hot catholyte and acidifying of said hot anolyte, discharging said hot catholyte to the exterior, retaining said hot anolyte as a hot rinse solution, and then subjecting the dishes to a rinsing action with said hot rinse solution.

13. The method of washing dishes comprising providing cold raw water having dissolved therein small amounts of metal salts, heating and introducing a quantity of detergent into a first portion of said cold raw water to produce a hot wash solution, subjecting the dishes to a Washing action with said hot Wash solution, conducting second and third portions of said cold raw water into cooperating relation with the opposite sides of a diaphragm and simultaneously conducting an electric current therebetWeen and through said diaphragm so that said second and third portions or" said cold raw water respectively constitute a catholyte and an anolyte with the result that the anions and the cations of the dissolved metal salts therein are respectively concentrated in said anolyte and in said catholyte effecting simultaneous alkalizing of said catholyte and acidifying of said anolyte, dis- 22 charging said catholyte to the exterior, heating said anolyte to produce a hot rinse solution, and then subjecting the dishes to a rinsing action with said hot rinse solution.

14. Dishwashing apparatus comprising a vat adapted to receive dishes to be Washed, a supply conduit adapted to be connected to a source of Water under pressure and having dissolved therein small amounts of mineral salts, structure provided with a channel therethrough, a drain conduit, a first connection from said supply conduit directly to said vat, a second connection from said supply conduit via said channel to said vat, a third connection from said vat to said drain conduit, first inlet mechanism selectively operative to control the introduction of Water into said vat via said first connection, second inlet mechanism selectively operative to control the introduction of water into said vat via said second connection, means for preferentially extracting from the Water passing through said channel the cations with respect to the anions of the mineral salts dissolved therein so as simultaneously to demineralize and to acidify the same, drain mechanism selectively operative to control the draining of Water from said vat via said third connection, a motor operative to circulate the water in said vat into contact with the dishes therein, and means for selectively operating said first and second inlet mechanisms and said drain mechanism and said motor in a predet rmined sequence in order to produce a given Washing cycle in said vat.

15. The dishwashing apparatus set forth in claim 14, and further comprising a Water heater arranged in said supply conduit so that the water supplied to said channel and to said vat is hot.

16. The dishwashing apparatus forth in claim 14, and further comprising a Water heater arranged in said second connection between said channel and said vat so that the demineralized water supplied from said channel to said vat is hot.

17. The dishv/ashing apparatus set forth in claim 14, wherein said given Washing cycle includes a washing step in which the Wash Water employed in said vat is introduced thereinto via said first connection and a rinsing step in which the rinse Water employed in said vat is intro duced thereinto via said second connection.

18. The dishwashing apparatus set forth in claim 14, wherein said cation extracting means includes a facility for conducting an electrolytic current through the Water passing through said channel.

19. The dishwashing apparatus set forth in claim 14,

wherein said cation extracting means includes a porous ion exchange bed arranged in said channel and accommodating the ready passage therethrough of the water passing through said channel.

20. Dishwashing apparatus comprising a vat adapted to receive dishes to be Washed, a supply conduit adapted to be connected to a source of Water under pressure and having dissolved therein small amounts of metal salts, a Water-treatment unit provided with main and auxiliary channels therethrough and operative to transfer metal cations of dissolved metal salts from water passing through said main channel into water passing through said auxiliary channel, a drain conduit, means for conducting water from said supply conduit via said auxiliary channel into said drain conduit, a first connection from said supply conduit directly to said vat, a second connection from said supply conduit via said main channel to said vat, a third connection from said vat to said drain conduit, first inlet mechanism selectively operative to control the introduction of water into said vat via said first connection, second inlet mechanism selectively operative to control the introduction or" water into said vat via said second connection, drain mechanism selectively operative to control the draining of Water from said vat via said third connection, a motor operative to circulate the water in said vat into contact with the dishes therein, and means for selectively operating said first and second inlet mechanisms and said drain mechanism and said motor in a predetermined sequence in order to produce a given washing cycle in said vat, wherein said given washing cycle includes a washing step in which the wash water employed in said vat is introduced thereinto via said first connection and a rinsing step in which the rinse water employed in said vat is introduced thereinto via said second connection,

21. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of water under pressure having dissolved therein small amounts of metal sans, a water-treatment unit provided with main and auxiliary channels thcrethrough and operative to transfer a substantial proportion of the cations of the dissolved metal salts from water passing through saidrnain channel into water passing through said auxiliary channel and to transfer a substantial proportion of the anions of the dissolved metal salts from water passing through said auxihary channel into water passing through said main channel, whereby water passing through said main channel is acidified and water passing through said auxiliary channel is alkalized, a drain conduit, means for conducting water from said supply conduit via said auxiliary channel into said drain conduit, a first connection from said supply conduit directly to said vat, a second connection from said supply conduit via said main channel to said vat, a third connection from said vat to said drain conduit, first inlet mechanism selectively operative to control the introduction of water into said vat via said first connection, second inlet mechanism selectively operative to control the introduction of water into said vat via said second connection, drain mechanism selectively operative to control the draining of water from said vat via said third connection, a motor operative to circulate the water in said vat into contact with the dishes therein, and means for selectively operating said first and second inlet mechanisrns and said drain mechanism and said motor in a predetermined sequence in order to produce a given washing cycle in said vat, wherein said given washing cycle includes a washing step in which the wash water employed in said vat is introduced thereinto via said first connection and a rinsing step in which the rinse water employed in said vat is introduced thereinto via said second connection.

22. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of water under pressure and having dissolved therein small amounts of metal salts, structure defining first and second chambers and provided with a permeable barrier as a common wall therebetween, a drain conduit, means for conducting water from said supply conduit through said first chamber into contact with said barrier and thence into said drain conduit, means for selectively conducting water from said supply conduit directly into said vat, means for selectively conducting water from said supply conduit through said second chamber into contact with said barrier and thence into said vat, means for selectively conducting water from said vat into said drain conduit, and means for conducting an electric current from the water in one of said chambers through said barrier into the Water into the other of said chambers in order to modify both the electrolytic concentration and the pH of the water in both of said chambers.

23. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of water under pressure and having dissolved therein small amounts of metal salts, structure defining first and second chambers and provided with a permeable barrier as a common wall therebetween, a drain conduit, means for conducting water from said supply conduit through said first chamber into contact with said barrier and thence into said drain conduit, means for selectively conducting Water from said supply conduit directly into said vat, means for selectively conducting water from said supply conduit through said second chamber into contact with said barrier'and thence into said vat, means for selectively conducting water from said vat into said drain conduit, a cathode in contact with the water in said first chamber, an anode in contact with the water in said second chamber, and means for conducting an electric current from said anode through said barrier to said cathode, whereby the concentration of the cations of the dissolved metal salts in the water s cond clamber is reduced and also the pH of the c ca, second chamber is reduced.

24. ljishwashlng apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of Water under pressure and having dissolved therein small amounts of metal salts, s ructure deiinln first and second chambers and provided th a permeable barrier as a common wall therebetween, a drain conduit, trap structure connected to said drain conduit, means for conducting water from said supply conduit through said first chamber into contact with said barrier and thence into said trap structure, means for selectively conducting water rrom said supply conduit directly into said vat, means for selectively conducting water from said supply conduit through said second chamher into contact with said barrier and thence into said vat, means for selectively conducting Water from said vat into said trap structure, said trap structure overflowing into said drain conduit, and means for conducting an electric current from the water in said first chamber tirough said barrier into the Water in said second chamber in order to modify both the electrolytic concen ration and the pH of the water in both of said chambers, whereby the pI-l of the water in said first chamber is increased above 7.0 the pH of the water in said second chamher is reduced below 7.6.

25. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source or" water under pressure and having dissolved therein small amounts of metal salts, structure defining first and second chambers and provided with a permeable barrier as a common wall therebetween, a drain conduit, means for conducting water from said supply conduit through said first chamber into contact with said barrier and thence into said drain conduit, a porous ion exchange bed arranged in said second chamber, means for selectively conducting Water from said supply conduit directly into said vat, means for selectively conducting water from said supply conduit through said second chamber and said bed and into contact with said barrier and thence into said vat, means for selectively conducting water from said vat into said drain conduit, a cathode in contact with the water in said first chamber, an anode in contact with the water in said second chamber, and means for conducting an electric current from said anode through said barrier and said bed to said cathode, whereby the concentration of the cations of the dissolved metal salts in the water in said second chamber is reduced and also the pH of the water in said second chamber is reduced.

26. The dishwashing apparatus set forth in claim 25, wherein said bed essentially comprises a loosely packed mass of discrete particles of ion exchange material.

27. The dishwashing apparatus set forth in claim 25, wherein said bed essentially comprises a loosely packed mass of discrete particles of cation exchange material.

28. The dishwashing apparatus set forth in claim 25, wherein said bed essentially comprises a loosely packed mass of first discrete particles of cation exchange material and of second discrete particles of anion exchange material.

29. The dishwashing apparatus set forth in claim 28, wherein said cation exchange material essentially comprises synthetic organic polymeric cation exchange resin and said anion exchange material essentially comprises synthetic organic polymeric anion exchange resin.

30. The dishwashing apparatus set forth in claim 25, wherein said ion exchange bed is characterized by regeneration of the cation exchange capacity thereof upon conduction of an electric current therethrough when no raw water is being conducted through said second chamber.

31. In dishwashing apparatus including a cabinet, a vat arranged in said cabinet and adapted to receive the dishes to be washed, structure defining a doorway from the exterior into said vat, and a door cooperating with said structure and movable between open and closed positions with respect to said doorway; the combination comprising a supply conduit adapted to be connected to a source of water under pressure and having dissolved therein small amounts of mineral salts, structure arranged in said cabinet exteriorly of said vat and provided with a channel thcrethrough, a drain conduit, a first connection from said supply conduit directly to said vat, a second connection from said supply conduit via said channel to said vat, a third connection from said vat to said drain conduit, first inlet mechanism selectively operative to control the introduction of water into said vat via said first connection, second inlet mechanism selectively operative to control the introduction of Water into said vat via said second connection, means for preferentially extracting from the water passing through said channel the cations with respect to the anions of the mineral salts dissolved therein so as simultaneously to demineralize and to acidify the same, drain mechanism selectively operative to control the draining of water from said vat via said third connection, a motor operative to circulate the water in said vat into contact with the dishes therein and control means for selectively operating said first and second inlet mechanisms and said drain mechanism and said motor in a predetermined sequence in order to produce a given washing cycle in said vat.

32. The dishwashing apparatus combination set forth in claim 31, wherein said control means repeatedly operates said first inlet mechanism to effect the introduction of water into said vat in each of a plurality of washing steps and also in an initial rinsing step, and said control means operates said second inlet mechanism to efiect the introduction of water into said vat in a final rinsing step.

33. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of raw Water, means for selectively controlling the supply of raw water from said supply conduit to said vat, a water-treatment unit, means for supplying raw water from said supply conduit to said umt, means for operating said unit to produce a first aqueous acidified solution and a second aqueous alkalized solution from said raw water supplied thereto, means for selectively controlling the supply of one of said aqueous solutions from said unit to said vat, a drain conduit, means for selectively controlling the draining of liquid from said vat into said drain conduit, and means for discharging the other of said aqueous solutions from said umt mto said drain conduit.

34. Dishwashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of raw water, means for selectively controlling the supply of raw Water from said supply conduit to said vat, a water-treatment unit, means for supplying raw water from said supply conduit to said unit, means for operating said unit to produce a first aqueous acidified solution and a second aqueous alkalized solution from said raw water supplied thereto, a heater, means for selectively controlling the supply of one of said aqueous solutions from said unit via said heater to said vat, a drain conduit, means for selectively controlling the draining of liquid from said vat into said drain conduit, and means for discharging the other of said aqueous solutions from said unit into said drain conduit.

35. Diswashing apparatus comprising a vat adapted to receive dishes to be washed, a supply conduit adapted to be connected to a source of raw water, means for selectively controlling the supply of raw water from said supply conduit to said vat, a water-treatment unit, means for supplying raw water from said supply conduit to said unit, means for operating said unit to produce a first aqueous acidified solution and a sceond aqueous alkalized solution from said raw water supplied thereto, means for selectively controlling the supply of said first aqueous solution from said unit to said vat, a drain conduit, trap structure arranged between said vat and said drain conduit, means for selectively controlling the draining of liquid from said vat into said trap structure, and means for discharging said second aqueous solution from said unit into said trap structure, liquid entering said trap structure overflowing therefrom into said drain conduit.

36. The method of washing dishes set forth in claim 1, wherein said preferential extraction fiom said second portion of said raw water of the cations with respect to the anions of said dissolved metal salts comprises an ion exchange step.

37. The method of washing dishes set forth in claim 1, wherein said preferential extraction from said second portion of said raw Water of the cations with respect to the anions of said dissolved metal salts comprises an electrodialysis step.

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