US2711179A - Dishwashing machine - Google Patents

Description

June 21, 1955 J. 1.. ANDR EWS 2,711,179

DISHWASHING MACHINE Filed Nov. 50, 1953 2 Shets-Sheet 1 June 21,1955 WS 2,711,179:

DISHWASHING MACHINE Filed Nov. 30, 1953 I I 2 Sheets-SheetZ fzwezzfoz" 1705722. fizz dram) United States PatentO DISHWASHING MACHINE John L. Andrews, Chicago, Ill., assignor to General Electric Company, a corporation of New York Application November 30, 1953, Serial No. 395,120

4 Claims. (Cl. 134-186) This invention relates to dishwashers, and, in'particular,

operations and for certain of the rinsing operations. It

is customary, for example, to use only about twelve pints of water for each of said operations. Certain types of dishwashers use an impeller disposed in a sump or other low portion of the dishwasher tub to pick .u'pliquid which collects in said sump and throw it forcefully about, whereby the dishes and other articles are subjected to the cleansing action of multitudinous particles of washing or rinsing liquid. A single washing operation maybe of five minute duration, and it is obviously important to prevent drainage from the tub so asto conserve the charge of washing liquid, for water loss during that period would quickly reduce the eificiency of the impeller.

Mechanically operated drainage valves and valve systems are well-known andcommonly used in dishwashers. They are, however, subject to mechanical failure either because of failure of the operating mechanism itself, 'or because of food particles or thelike becominglodged under the valve disc or other valve member. 'It has'also been proposed to eliminate mechanical drain valves by providing a drainage opening in the tub about the impeller axis and utilizing a radially bladed centrifugal pump fixed to the dishwasher impeller to sweep the water away from said opening during periods of rotation of the impeller. This arrangement performs satisfactorily as a drainage control device but issubject to the criticism that the action of the centrifugal pump blades repels the liquid from the dishwasher impeller itself and thereby interferes with the necessary pickup of liquid by the impeller.

It is therefore an object of my invention to provide 'a dishwasher having a drainage control system which does not embody mechanically operated valves or the like.

It is another object of my invention to provide a dishwasher having a drainage control system of the valveless type which does not interfere with or detract from the operation of the dishwasher impeller.

It is a further object of my invention to provide a dishwasher having a drainage opening coaxial with the impeller shaft, and to arrange for operation entirely within said opening a rotating member having means for effectively preventing flow of water through said opening whilethe dishwasher impeller is in operation and permitting free flow of washing or rinsing liquid to the drain'when the impeller is quiet.

It is a further object of the invention to provide a valveless drainage control system which is self-cleaning and which will not thereforeaccumulate or retain particles of food waste.

In a presently preferred embodiment, I utilize a conventional dishwasher impeller disposed in a sump or other low part of. the dishwasher tub. Said'impeller .is wholly above, and its driving means and other accessory structures extend through, a relatively large opening which is 2,711,179 Patented June 21, 1955 2 coaxial therewith. Afiixed to said impeller for rotation therewith, and extendingv through said opening, is a drainage control device which comprises a plurality of spirally arranged vanes operating with relatively small clearance I impeller blades.

Other features and advantages will be apparent :from the following detailed description of a presently preferred embodiment of the invention read in connection with the accompanying drawingin which: i

Fig. 1 is a side elevationof the'lower portion of a dishwasher embodying the invention with the dishwasher tub impellerand other elementsin vertical section;

Fig. 2 is a plan'section looking in the direction of the arrows 2-2 of Fig. 1; i I

Fig. 3 is a top plan view showing the method of attachment of the drainage control device to the motor shaft and the manner in which said attachment also serves to transmit motor torque to the impeller; and Y Fig. 4 is a side elevation, partly insection, of the impeller and drainage control assembly; and v a Fig. 5 is a schematic wiring diagram illustrating a method of automatically electrically controlling the dishwashing apparatus to perform a-timed sequence of rinsing, washing, and draining operations. 7 I

Fig. 1 shows the lower portion of a dishwasher embodying the present invention. The dishwasher-1 may be of the general type disclosed in the F. A. Walker U. S. Patent No. 2,657,697, issued to'my present assignee on November 3, 1953, for Dishwashing Apparatus and Cabinet.

.mounted within an, external-cabinet and containing the roller provided racks 3 arranged to be drawn outward through a front opening of the tub when thedoor-ql thereof is swung down from its substantially vertical closed position to a substantially horizontal open position. Mounted on an inner liner of said door, so as to face the interior of the cabinet, is a detergent dispenser D, as shown in said Walker patent. Theuser opens the door, rolls out the racks, loads them with the dishes and other articles and returns the rack to the tub. Thereupon a charge of granular detergentis placed in thedispenser D and the door closed. r

The bottom of the tub slopes downward to form a substantiallyfiat-bottomed sump 5. An impeller 61's arranged within the sump for rotationon a vertical axis. The impeller is preferably'of the type disclosed in 'U. S. Patent 2,422,022, granted June 6, 1947, to NH; Koertge for Dishwashing and Drying Apparatus. Said impeller has liquid circulation blades 7 and air circulation blades 8. As best shown in Fig. 4, the bottom of the blades 7 is flat'and relatively close to the surface of sump 5. The drive motor 9 is suitably mounted below the tub, as on brackets 10 or by other appropriate means; The-motor shaft 11 extends upwardly through a'guard tube 12,which terminates above the maximum free levelof liquid in the sump under operating conditions and thus prevents escape of water into the machinery space below the tub. Said guard tube may conveniently be formed as part of a drainage chamber 14, secured to the tub bottom by machine screws or other equivalent means. The chambermaybe a casting or of sheet metal construction as desired. In operation, the impeller blades 7 pickup the free water in the sump and scatterit forcefully throughout the tub and over the articles racked therein. The normal charge. of water for a washing orv a power rinsing operationis about twelve. pints. This quantity, if permitted 7 to accumulate in the sump, would submerge the lower sump is suflicient only to submerge the lowermost portion of the blades 7, the remainder being in upward and outward motion within the tub and returning to the sump by downflow along the walls and bottomfof'the tub or dropping from the articles being washed. The flow to the impeller is also controlled, in a sense, by the guard screen 15, which is supported on suitable means (not shown) concentric with the impeller. The apertures in said screen are variously sized to catch food particles for preventing redeposit on the articles within the tub, and as such serve to meter the water flow to the impeller. During as much of the operating cycle as: may be desired. a heating element 16 may be energized to prevent chilling of the water during the water-using operations of the dishwasher. During a subsequent drying cycle, the blades S'of the impeller draw air upwardly within the impeller hub and outwardly through the openings 8.1 thereof to cause a circulation of air over the adjacent heating element to abstract heat therefrom. The circulation of warm air over the washed and rinsed dishes provides an efiicient means of drying the dishes so that at the end of the complete operation cycle the dishes are ready for storage or for reuse.

Water for washing and rinsing the dishes may be introduced into the tub under the automatic control of a solenoid operated inlet valve system 17 which receives water through the inlet tube 18 connected to the hot water supply piping (not shown) and discharges the water through a tube 19 which connects to an inlet fitting 19.1 (shown schematically in Fig. at the top of the tub. Said inlet fitting may be of the type disclosed in the Frank D. Low Patent No. 2,665,700, granted January 12, l954,-for Liquid Inlet and Antiback-Siphoning Fixture and assigned to my present assignee. The inlet fitting is effective to introduce the liquid into the tub in a spray pattern. Drainage from the tub enters the drainage housing 14 through an opening20 in the bottom of the sump, and in the illustrated embodiment will flow by gravity thru the drainage piping 14.1 which connects with the plumbing waste system (not shown).

The present invention comprises means for controlling drainage through the opening 20. As best appears in Fig. 3, I aflix to the non-circular end 21 of shaft 11 a cylindrical drainage control member 22, which extends through the opening 20 into the drainage chamber 14. The cylinder 22 is fitted with a plurality-illustratively four-of spirally arranged blades 23 projecting therefrom. Each blade comprises a segment of a screw of suitable pitch, and, as clearly appears, each is so arranged as to place the center portion of its length approximately in line with the bottom wall of the sump 5. Preferably, the leading edge of one blade is below the trailing edge of an adjacent blade and the blades reach relatively close to the edge of the opening 2.0. The blades are uniformly pitched, and the leading edges and the trailing edges are in respectively the same horizontal plane. The cylinder 22 is securely mounted on the shaft 11 for rotation therewith by a yoke 24 which fits over the shaft and has diametrically opposed arms '25 which extend outwardly and downwardly into juncture with the cylinder. The impeller hub 26 fits over the yoke portion and is keyed thereto by internal moulded shoulders 27 which engage each side of the legs 25 of, the yoke. When 'the'bolt 28 is tightened, the top wallof the impeller hub seats securely against the surface of the yoke 24. By taking suitable manufacturingsteps to insure squareness and concentricity of the reduced end portion 21 of the shaft 11, the assembly of the impeller hub and yoke can be mounted and maintained with the accuracy necessary to insure the concentricity of the blades 23 relative to the opening 20. The actual length of cylinder 22 appears of minor importance, although it preferably extends from I well up within the hub to a point just below the bottom of sump 5. As clearly appears in Fig. 4, the impeller hub 26 has a relatively small, but nevertheless well defined, clearance with respect to the cylinder 22, and is in parallel relation thereto.

Fig. 5 shows in schematic form an automatic timecycle operation for a dishwashing machine embodying the present invention.

For example, the dishwasher may have mounted on an external wall thereofa time-cycle controller 30 of the general type shown in Illian U. S. Patent 2,619,557, which issued November 25, 1952, for Program Selector Switch. Said controller has a conventional timer motor 31 driving. through a friction clutch 32, a shaft 33. Said shaft carries a set of four insulated cams C1, C2, C3, 'C4' and a manually operable control knob 34 mounted ex-i Each cam is operatively associated with a single pole, single throw, spring contact switch. Cam C1 controls switch S1 which 'is in circuit with the timer motor as follows: Line conductor-40, conductor 41, switch S1, conductor 42, timer motor 31 and thence to lineconductor 43. Cam C2 controls switch S2 in circuit with they heating element 16 by means of the conductors 44. and 45. Cam C3 controls switch S3 in circuit with the impeller motor 9 by means of conductors 46 and 47. Cam C4 controls switch S4 in circuit with inlet valve solenoid 17.1' by means of conductors 48 and 49.

Assuming the machine to be loaded with dishes to be washed and the detergent added, the user manually rotates the control knob 34 to on position. This brings a high point of cam C1 into registry with switch 81, closing the switch andenergizing the timer motor 31 through the obvious circuit. Shortly after the timer motor begins to rotate shaft 33, a high point of cam C4 controls switch S4 causing it to close to energize the solenoid coil 17.1 of inlet valve 17 and thus causing the introduction of hot water into the tub 2 through the spray fitting 19.1 of the top thereof. The incoming spray of water loosens the soil from .the dishes and other articles to be washed. Now it will be observed that the control switch S3 for the impeller motor 9 is open at this time. The motor is therefore quietand the drain control cylinder 22 is, not rotating. The rinse water may then flow freely through the opening 20 and .into the drainage fitting ,14, whence it flows by gravity to the plumbing drain. While the inlet valve 17 remains open, cam C3 engages with switch 83 causing it to close and energizing the motor 9 through the obvious circuit. It will be assumed that motor 9 rotates the impeller 6 and the drainage control cylinder 22 at approximately 1750 R. P. M. in a counterclockwise direction, as viewed in Figs. 2 and 3, and'drainage of liquid will almost immediately cease.

As clearly appears in Fig. 4, he blades extend angularly across the wall of the sump 5, and reach intoclose proximity with the edge of the opening 20. From observation and analysis, it appears that theinsignificant amount of water loss during a washing and power rinsing operation may be the result of a combination of effects produced by the angle of attack of blades 23, and the relationship of the cylindrical member 22 to the closely adjacent inner wall of the cylindrical 'hub of the impeller" I 6. Water which finds its way below theirnpellerblades will spill over the wall of opening 20 onto the:blad es 23. It is known that the rapid rotation of the bladescauses the water impinging upon them to climb'on the blades and to be thrown outwardly and'upwardly there from, Some of this water will strike the bottomportions;

It is to be understood, however, that the invention is equally applicable to manually 'controlled apparatus.

of the impeller blades and be deflected tangentially outwardly thereby. It appears probable that a substantial portion of the water will tendto climb the cylinder 22, aided by the air stream cerated by the blades 23 and the air fan blades 8 of the impeller, and will eventually escape through the opening 8.1 to pass into the main body of liquid being circulated by impeller action. Even if the cylinder 22 were to extend upwardly within the impeller hub for only a fraction of its length, it is believed that the liquid will transfer to the hub wall and continue to climb to the level of the openings 8.1.

The self-cleansing of the drainage control blades 23 is also attributed to this upward movement of water within the impeller hub. To this extent, the present invention utilizes the principle disclosed inWotring U. S. Patent 2,544,374, which issued on March 6, 1951, for Dishwashing Apparatus Impeller and is assigned to my present assignee. Food soil which is small enough to penetrate the screen 15 will not accumulate on or about the blades 23 or the cylindrical element 22 of the drainage control system.

As the full charge of liquid accumulates and attains a greater depth in the sump 5, the rotating impeller induces the liquid about the impeller into a counterclockwise rotation which of itself tends to keep liquid from reaching the opening 20 in appreciable amounts.

It is noted from the schematic control diagram that the inlet valve is closed while the impeller remains in operation for the completion of the wash period. The motor is de-energized to signify the end of the washing operation and the liquid in the tub is free to flow over the blades 23 and into the drainage chamber 14.

After a quiescent period calculated to permit full drainage, the motor is again started as the cam C3 again closes switch S3, and either coincidentally therewith or immediately thereafter, cam C4 closes the inlet valve switch S4 to elfect a second introduction of water. Because the charge of detergent was usedup during the washing operation, the dishes will now be subjected to a thorough power rinse with clear water. The duration of said power rinse is illustratively as long as the washing operation.

The motor is again stopped to permit drainage of the rinse water. Other, shorter, rinsing operations may follow, during which the motor 9 may or may not be energized, as desired. The machine then enters a drying cycle during which time the motor 9 operates to circulate warm air over the articles in the tub. At the end of the drying cycle, which may approximate one-half of the total time of the complete wash, rinse, and dry sequence, the timer reaches the off point and restores all switches to open circuit status.

While there has been described what is at present considered to be the preferred embodiment 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:

1. In a washing machine, a tub arranged to receive a quantity of water for washing articles disposed within said tub, said tub being formed with a sump portion hav-- ing a drainage opening, an impeller shaft extending through said opening, a drainage control member fixed to said impeller shaft for rotation therewith, a plurality of drainage control blades carried by said member and extending into relatively close proximity with the wall of said opening, each of said blades extending through said opening and comprising a segment of a screw of uniform pitch spiralling upwardly as respects the direction of rotation of said shaft, an impeller carried by said shaft wholly above said sump portion for enforcing circulation of water throughout said tub, said impeller having blade members extending horizontally outward over and beyond said drainage opening and said drainage control blades in relatively close spaced relation therewith, and means for peller shaft will be moved upwardly against said impeller blade members and thrown radially outwardly thereby.

2. In a dishwashingmachine, a tub arranged to receive a quantity of water for washing articlesdisposed within said tub, said tub being formed with a relatively flatbottomed sump portion having a drainage opening, a con:

centrically "disposed impeller shaft extending vertically through said opening, a drainagecontrol member fixed to said impeller shaft for rotation therewith, a plurality of drainage control blades carried by said member and extending into relatively close proximity with the wall of,

said opening, each of said blades extending through said opening and comprising a segment ofa screw of uniform pitch spiralling upwardly as respects the direction of rotation of said shaft, an impeller carried by said shaft wholly above said sump portion for enforcing circulation of water throughout said tub, said impeller having relatively flat blade portions overlying said drainage control blades and the bottom of said sump in relatively close spaced relation with said sump and said blades and having a substantially cylindrical hub portion enveloping said drainage control member from a point a short distance above said drainage control blades, and means for rapidly rotating said impeller shaft.

3. In a dishwashing machine, a tub arranged to receive a quantity of water for washing articles disposed within said tub, said tub being formed with a sump portion having a drainage opening, a concentrically disposed impeller shaft extending vertically through said opening, a cylindrical drainage control member fixed to said impeller shaft in concentric relation with said opening, a plurality of drainage control blades secured to said cylindrical member and extending outwardly therefrom into close proximity to the wall of said opening, each of said blades extending angularly through said opening and comprising a segment of a screw of uniform pitch, means for. rotating said impeller shaft in a direction in which the trailing ends of said drainage control blades are uppermost, an

impeller for circulating water among the articles in said tub, said impeller having a substantially cylindrical hub portion fixed to said impeller shaft and enveloping said cylindrical drainage control member in relatively close spaced relation therewith, the bottom of ,said impeller hub portion being in relatively close proximity to the trailing ends of said drainage control blades whereby water reaching said drainage control blades will be directed into the annular space between said hub and said cylindrical member, and means for permitting the return of said directed water into said tub.

4. In a dishwashing machine, a tub arranged to receive a quantity of water for washing articlesdisposed within said tub, said tub being formed with a sump portion having a drainage opening, a concentrically disposed impeller shaft extending vertically through said opening, a cylindrical drainage control member fixed to said impeller shaft in concentric relation with said opening, a plurality of drainage control blades secured to said member and extending outwardly therefrom into close proximity to the wall of said opening and collectively comprising substantially a complete circle, each of said blades extending angularly through said opening and comprising a segment of a screw of uniform pitch, common extremities of each blade being in the same plane, an impeller disposed within said sump above said opening for circulating Water among the articles in said tub, said impeller having a substantially cylindrical hub portion fixed to said impeller shaft and enveloping said drainage control member with finite clearance'therebetween, said hub portion extending upwardly from a point a short distance above said blades and having radially extending openings in an upper por- UNITED STATES PATENTS Buck et a1. Ju1 -30, 1929 Long Sept. 26, 1933 48 F Stoddard Dec. 3, 1935 Power's Apr. 1, 1947 Holle'rith Dec. 27, 1949 Sway. Oct. 6, 1953

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