US2751917A - Dishwashing machine - Google Patents

Description

June 26, 1956 Filed Jan. 4, 1952 F. D. LOW

DISHWASHING MACHINE 2 Sheets$heet l June 26, 1956 F. D. LOW 2,7

DISHWASHING MACHINE Filed Jan. 4, 1952 2 Sheets-Sheet 2 DISHWASmG MACHINE Frank D. Low, La Grange Park, 111., assignor to General Electric Company, a corporation of New York Application January 4, 1952, Serial No. 264,873

Claims. (Cl. 134-176) This invention relates to an improved dishwashing ma chine.

In particular, the invention relates to improved water circulation and drainage in dishwashers of the type in which washing liquid is forcefully sprayed throughout a vat or tub within which are arranged the dishes and other articles to be washed. The circulation of washing liquid is effected by a pump having an inlet connection at a low point of the dishwasher vat and a discharge connection to the spray nozzles or the like which create washing action within the tub.

As is now well known, dishwashing apparatus of both domestic and commercial types include automatically established and controlled operational periods during which the articles are subjected to various rinsing and washing steps under control of conventional time-cycle switches. Between each operation spent or soiled Washing or rinsing liquid is discharged from the machine. During the washing and rinsing operations, the dishwasher makes efr'icient use of relatively small quantities of water-for example, a domestic dishwasher having a capacity of 60 dishes and accompanying tableware uses only 12 pints of water for certain of the washing and rinsing cyclesand it has heretofore been considered necessary to provide a valve in the tub drain line to prevent loss of water during these operations. Such valves are subject to mechanical failure, and in the event they should fail to close completely, or stick in closed position, improper washing or rinsing may result.

Accordingly, it is a principal object of my invention to provide a dishwashing apparatus in which control over the drainage of water therefrom is satisfactorily accomplished without drain valves of any kind.

it is another object of my invention to provide a dishwashing apparatus in which the operation of pumping means to circulate washing or rinsing liquid within the tub will control the drainage of liquid from the tub.

It is a further object of the invention to provide an improved liquid circulation system for dishwashers or the like.

Presently preferred embodiments of the invention will best be understood from the following detailed description read in connection with the accompanying drawings, in which Fig. l is a side sectional elevation of one form of dishwasher, showing an arrangement of dish and glass racks relative to the water distributor; Figs. 2 and 3 are somewhat schematic representations of other water circulation and drainage control arrangements; and Fig. 4 and Fig. 5 are side sectional elevations of drainage connections, respectively showing a drain branch in which an aspirator action results from pump operation and prevents escape of liquid to the drain, and a second form and arrangement of branch in which there will be a constant slow escape of liquid during pump operation.

in the embodiment of Fig. 1, a dishwasher 1 includes a cabinet or frame 2 within which is rigidly secured a tub or vat 3. Said tub has a front opening which is. arranged to be closed during operation by a door 4 having a bottom- Patented June 26, 1956 hinged connection with the casing; the hinge mechanism and arrangement may be that described and claimed in my U. S. Patent 2,573,798, which issued November 6, 1951, and is assigned to my present assignee. As is more particularly described therein, the door 4 swings downwardly to a position in which an inner Wall 5 forms a horizontal shelf onto which the dish rack assembly 6 may be rolled for loading. The rack has a pair of front rollers 7 and rear rollers 8, the latter cooperating with the rails 9 extending along the side walls of the tub as is now well known. It may be noted that pursuant to conventional practice the upper portion 6.1 of the rack is removably supported on the main rack 6,'being spaced suitably above the upper rim of said rack by support legs 6.2. Dishes, platters, etc., are placed in the lower rack 6, tableware in the cuplike container 6.3, and glasses, cups, etc., in the upper rack 6.1. The illustrated solenoid operated water supply valve 10 receives hot water from a suitable source (not shown) and according to the energization of its solenoid 11 controls water flow through the tube 12 to a spray-type inlet fitting 14 mounted at the top of the tub and discharging thereinto. The solenoid controlled valve and inlet fitting 14 are well known. For example, the inlet fitting may be as shown in my present pending application, Ser. No. 157,362, filed April 21, 1950, for Vat and Combination Liquid Inlet and Anti Back-siphoning Fixture and assigned to my present assignee.

Finally, it may be considered that the dishwasher is of the automatic time-cycle type in which a timer-motor driven sequence switch 15 directs the apparatus through a series of operations which may include a spray rinse, a wash, a second wash, a first rinse, and a final rinse. Such switches are well known in the art and may be, for example, as shown in U. S. Patent 2,536,256, which issued January 2, 1951, to Ralph L. Berg. It should be understood, however, that the dishwashing apparatus may be manually controlled. It will also be understood that any suitable conventional means (not shown) may be employed for introducing a detergent compound into the tub during the respective washing operations.

The liquid circulation and drainage control systems embodying the invention are best shown in Fig. 1. A pump 16 is preferably directly driven by a motor 17 under the control of time-cycle switch 15 or an equivalent manually controllable switch (not shown). Usually, such pumps are of conventional centrifugal type. In any event, it will be considered that the pump receives liquid through an inlet pipe 18 communicating by way of a tub drainage fitting 2% with the sump portion 21 of the tub. Preferably, the inlet pipe 18 is vertically arranged, or at least has a vertical run portion intermediate its ends. The discharge 22 from the pump communicates by way of the vertically extending pipe 23 with a rotatably mounted spray device 24. Said device is free to whirl in a horizontal plane intermediate the upper and lower dish rack portions. The spray device rotates as a result of the reaction pressure of liquid jets or sprays discharging from the plurality of spray heads 25 which are spaced at intervals along the tubular arms 26, which comprise closedended conduits served from the central fitting 27 arranged to rotate on the upwardly looking elbow fitting 28. it will be understood that each said spray head has an angularly directed discharge slot (not shown) or a nozzle portion to direct the washing liquid against the articles on the respective racks and effectively distribute the washing liquid throughout the tub in a desired pattern.-

'I have found that positioning the spray device 24 intermediate the upper and lower racks 6 and 6.1 has substantial operational advantages as compared with the conventional bottom-spray arrangements of Figs. 2 and 3. The freedom from interference with the water distribution pattern by improperly placed dishes, large platters etc, in the bottom rack assures efiicient washing action, as compared with spray systems in which all of the water is thrown upwardly from the bottom and, hence, strikes and is deflected by the numerous articles of the lower rack. Also, there is substantial freedom from the possibility that water, driving upwardly from below the heavily soiled dishes, will carry the soil to the glassware. In the improved arrangement of Fig. 1, clean Water is directed upwardly against the glassware and downwardly against the dishes, and the sprays'or streams of water impinge with greater force and cleansing effect against the articles in the adjacent racks.

The waste liquid disposal piping includes drain-branch 38 which extends angularly outward from the vertical portion'of the pump inlet pipe 13-,v and communicates with a conventional trap seal 31 which in turn connects to a plumbing waste line (not shown). t will, of course, be understood that the drain branch may communicate with the inlet pipe 18 by means of a conventional T fitting. swing check valve 32 may be employed as a safeguar against the return of water from the trap to the pump inlet. the tub intercepts large food particles such as fragments of lettuce or other leafy vegetables and prevents them from reaching the pump inlet.

The initial rinse is made only from the inlet fitting 14 which is constructed to spray the incoming liquid throughout the tub to dislodge the large particles of food from the dishes and to dissolve any readily water-soluble food soil therefrom. The motor and pump are still. The rinse water flows into the pipe 18, and because the pump itself is always flooded by water from any previous operation, the pipe will be full substantially to the level of the branch 30. The rinse water will be diverted into the said branch, whence it flows past the check valve into the trap 31. Large food particles will remain on the screen 33 for manual removal at some later time.

After the rinse has been completed and time has been allowed for drainage from the tub, water is again admitted through fitting 14, and either coincidentally therewith, or shortly thereafter, the motor is energized to operate the pump. The water inlet valve is held open under timecycle control for a sufiicient period to introduce the necessary amount of water. The pump is already P imed from the previous operation and because of its capacity relative to the gravity flow rate into and through the inlet pipe 18., can discharge water through conduit 23 and spray device 24 faster than water enters the pipe 18; hence,

there is no buildup of Water to the level of branch 30, and

no water is lost to the waste line. Under normal operation, the greater part of the washing liquid is in motion within the tub; it is striking the dishes and other articles and is dripping therefrom; and there is actually little if any accumulation in the sump. Even if there were such an accumulation, however, the rate at which the pump removes water from the pipe 18 exceeds the rate of fiow into and through the upper portion of the pipe and there would be no loss of water to the sewer.

At the completion of the wash cycle the motor is stopped. As thepump comes to rest, liquid in the vertical line 23 flows back through the pump and rises in .the pump inlet pipe 18 where it mingles with residual "apermitted bythe branch 30. The pump chamber is completely full and the pump is therefore primed for the next 'peration.

"lathe typical dishwasher cycle. mentioned earlier, a wash cycle of minutesduration follows. Water \1 Although it is not essential, a suitable ball or A removable screen 33 over the sump portion of enters the tub through nozzle 14 for a time period sufiicient to bring in the necessary wash water. The pump operates throughout the water inlet period and, of course, during the wash operation the water discharging powerfully from the spray device 24 produces a strong washing action throughout the tub. There is less food soil on the dishes at the commencement of the second wash, and when the pump stops, marking the end of the washing operation, there is a further cleansing of the pump 16 by the back flow from riser 23. a

After a suitable drainage period there are two short rinse periods, and at the end of each there is a drainage period. Following the final drain, the pump chamber remains full of clean. rinse water.

Figs. 2 and 3 show in schematic fashion other pump and drain control arrangements which in general will operate in the manner of Fig. 1. In Fig. 2, for example, the enlarged sump 21.1. houses a pump 16.1 having an intake 18.1 extending close to the base of the sump, and: a discharge 22.1 serving the spray device 24.1 located below the. dish racks. The. drain branch 3&1 extends angularly from the pump intake; for connection to a trap sidered preferable to equip the branch 30.1 with a check valve (not shown) as previously noted.

The embodiment of Fig. 3 is not basically difierent.

from that of Fig. 1, except in the arrangement of the impeller 24.2. and the relatively higher position of the drain branch 30.2 relative to the pump 16.2. It is considered that no check valve is required in the drain branch.

It will be observed that the respective screens 33.1 and 33.2 must provide for the passage of spray device feed pipes, and accordingly will be divided or otherwise arranged for removal from the: tub.

Figs. 4 and 5. show other drain. branch arrangements. In Fig. 4, branch 30.3 slopes downwardly toward inlet pipe 18.3,. and as the. water flows rapidly to the pump through said pipe, there is an aspiration efiect within the drain branch which positively prevents the entry of liquid into the branch. In this form of drainage branch connection it is preferable to provide a check valve which closes, against any possible back flow into the inlet pipe.

In Fig. 5 the drain; branch 3.0.4 is arranged to bleed oif a small amount of liquid during any washing or rinsing operation, and it is contemplated that an equivalent amount of water will be introduced into the tub through fitting 14 during. the entire operation. As shown, the branch 3.0.4 slopes downwardly away from pipe 15.4, and althoughthis. arrangement of itself will divert a small amount of water into the branch, the division may be more definitely controlled by providing an intercepting lip 30.5 of appropriate projection into the main flow through pipe; 18.4. The use of a. check valve is a matter of choice.

While there have been describedwhat are at present considered tobe the. preferred embodiments of the invention, 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.

I claim: r V V 1. In apparatus such as. dishwashers, and the like having. a tub throughout whichv a substantial quantity of liquid is to. be. circulated. for a. desired period and waste liquid discarded following saidv circulation period, the improvement in liquid circulation and disposal apparatus comprising a pump having an inlet port disposed beneath said. tub, motor means. for operating said pump, a substantially vertically disposed pump inlet pipe communieating directly between a sump at the bottom of said tub and the inlet portion of said pump for conveying liquid to said inlet port from said sump, a pump discharge pipe for returning liquid to said tub substantially above the free surface of any liquid accumulation within said sump, fluid circulation means connected to said discharge pipe within the upper portion of said tub for forcefully circulating the discharge of said pump throughout said tub and a waste liquid disposal pipe communicating directly with said inlet pipe substantially solely by means of a wall opening in said pump inlet pipe below said tub and in vertically spaced relation to said pump inlet port, said disposal pipe extending angularly from said inlet pipe; the discharge rate of said pump into said tub being greater than the rate of flow from said sump into and through said pump inlet pipe, whereby liquid within said inlet pipe will be prevented from rising to the level of the waste disposal pipe inlet for flow thereinto during the operation of said pump the volumetric capacity of said pump inlet pipe intermediate said pump inlet port and said waste disposal pipe inlet being substantially less than the volumetric capacity of said pump discharge pipe measured between the pump and the point of connection of said fluid circulation means to said pump discharge pipe.

2. Liquid circulation and disposal apparatus as in claim 1 in which said waste liquid disposal pipe communicates with said pump inlet pipe by means of a right angled branch connection and extends substantially horizontally from said pump inlet pipe.

3. Liquid circulation and disposal apparatus as in claim 1 in which the point of discharge from said pump into said tub is a relatively large distance above the inlet of said waste liquid disposal pipe.

4. Liquid circulation and disposal apparatus as in claim 1 in which a lip disposed within said inlet pipe in the path of liquid flow therethrough diverts a portion of said liquid into said waste liquid disposal pipe during the operation of said pump.

5. Liquid circulation and disposal apparatus as in claim 1 in which at its point of connection with said pump inlet pipe said waste liquid disposal pipe slopes toward said inlet pipe in the direction of flow of liquid into said pump.

References Cited in the file of this patent UNITED STATES PATENTS 1,009,223 Cochrane Nov. 21, 1911 1,617,021 Mitchell Feb. 8, 1927 1,646,142 Fassio Oct. 18, 1927 1,675,192 Murdock June 26, 1928 1,743,966 Goudard Jan. 14, 1930 1,928,683 Cammann Oct. 3, 1933 1,980,065 Johnston Nov. 6, 1934 2,492,288 Hollerith Dec. 27, 1947 2,540,301 Staege Feb. 6, 1951

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