US2760502A - Heating and drying means - Google Patents

Description

Aug. 28, 1956 H. M. RUMBAUGH l-IEATING AND DRYING MEANS Filed Oct. 19, 1954 3 Sheets-Sheet l mmvrolc HUGH M; RUMBAUGH FIG. 1

ea F u-wm ATTORNEYS 8. 1956 H. M. RUMBAUGH 2,760,502

HEATING AND DRYING MEANS Filed Oct. 19, 1954 3 Sheets-Sheet 2 ea s wm ATTORNEYS Aug. 28, 1956 H. M. RUMBAUGH 2,750,502

HEATING AND DRYING MEANS Filed Oct. 19. 1954' 3 Sheet 3 I FIG. 5

INVENTOR. HUGH M. RUMBAUGH 12a,, 5A Haw ATTORNEYS HEATING AND DRYING MEANS Hugh M. Rumbangh, Bath, Ohio Original application October 18, 1952, Serial No. 315,454,

now Patent lflo. 2,698,626, dated January 4, 1955. Dizietllggnd this application October 19, 1954, Serial No.

8 Claims. (Cl. 134105) The present invention relates to heating and drying means and particularly to heating and drying means applicable to dishwashers of the automatic type in which ware to be washed is subjected to a series of pre-washing, washing, rinsing and drying operations according to a predetermined cycle. This application is a divisional application with respect to my copending application Serial No. 315,454, filed October 18, 1952, now U. S. Patent No. 2,698,626, which is, in turn, a continuation-in-part of 'my application Serial No. 137,509, filed January 9,1950, now U. 8. Patent No. 2,624,356.

A general object of the invention is to provide washing apparatus having improved means for drying-washed ware quickly and with a minimum of heat. Stated another way, a general object of the invention is to provide a pattern of circulation of drying air that is markedly superior to the circulation patterns of the prior art, as more fully explained in the specification.

Another object of my invention is to provide for eifec-- v tive heating of water and drying air or other fluid employed in a dishwasher or in other apparatus. In connection with dishwashers, it is to be noted that conventional dishwashers utilize water-'imrnersible heating elements to maintain high water and air temperatures within the washing chamber. However, as used in conventional dishwashers, such elements are of limited eifectiveness for several reasons. No way has been found to limit fluid distribution by the impeller to only those fluids which are leaving the heat source. Even if the heating element surrounds and is adjacent to a conventional impeller, the turbulence created by the impeller will prevent selective distribution of only that fluid which has just been in contact with the heating element. Furthermore, immersion of the heating element adjacent the impeller is impractical because the concentration of waste particles to which it is thus exposed tends to bake on they element. Locations of an immersed element further away from the impeller greatly reduce the wiping velocity of water moving over the heating element and require an inordinately high relative volume of sump water. The heating efiectiveness of those machines having heating elements arranged in the path of the spray rather than in immersed position is particularly poor.

I have discovered that the effectiveness of heat transfer between the heating element and the fluid is increased if the fluid is moved in relatively turbulence-free condition past the heating element by means of a smooth roll such as the smooth impeller I employ in my dishwasher. This heat transfer mechanism may be adaptable to many uses, but it is particularly suited to use in my smooth impeller dishwasher. Through the combination of my smooth impeller and a co-extending heating element, the heating of both wash water and drying air is more effective in my dishwasher than in any previous machine.

Accordingly, one of the objects of the invention is to provide means to heat washing and drying fluid with a higher degree of efliciency than has heretofore been possible in a domestic dishwasher.

The following specification and accompanying draw-' mgs will make the above and other objects and advantages of my invention more apparent. It will be understood that the illustrated embodiment of the invention is merely exemplary.-

In the drawings:

Figure 1 is a'front view, partly broken away, of a dishwasher embodying my invention. For clarity, the dishwasher door isfretnoved in this view.

Figure 2 is 'a' side view in section of the dishwasher shown in Figure); In. this view the dishwasherdoor is included and is in its closed position. For clarity, theperforated screening plates referred to in the following specification are not shownin'this'view. Y

Figures 3 and 4 areschematic views illustrating certain features of my invention.

Figure 5 aview taken along line 5-'5 of Figure 4, the impeller roll 30 being excluded from this view. I The dishwasher I have illustrated-as embodying mypresent invention comprises a chest-or chamber 10 hava top wall 11, 'a floor or desk 12, side walls 13 and a rear wall 14. The frontwall of the chamber 10'is generally open, and closure ,of the front. of the chamber is effected by the door 15 which has a suitable handle 15A.

The chamber 10 is supported within a generally rectangular housing. 16, the side walls of the housing 16 and the chamber side walls 13 being welded together to suspend the chamber in its illustrated position. A suitable toespace 17 may be formed along the bottom front of the housing 16. The door 15 is hinged to the front wall 18 of thehousing and closes against a suitable resilient strip 19 of rubber or other material carried on the front flanges 20 of the washing chamber 10. The

chamber 10 is vented to atmosphere through a slot 21 cut throughone of the sidewallslll and the corresponding side wall of the housing 16. The slot 21 is shielded by a suitable splash shield 22. Another vent for dish drying purposes may be provided in the forward lower portion of the chamber 10. This vent may consist of a slot 25 in the front wall 18 and a slot 26 in the front flange 20, retaining plate 27 being welded to the flange 20 outside the slot 26 to prevent escape of water held in the lower portion of the chamber 10.

In the lower portion of the chamber 10 and extendtransversely thereof is an impeller 30 mounted concentrically on a shaft 31 by means of the internal spacer discs 32 recessed within the ends of the impeller 30. The shaft is supported on suitable bearings carried on the lower front flange 20 and the rear wall 14. The shaft 31 extends through the rear wall 14 and carries a V-pulley 35 driven by a reversible motor 36 by means of a V-belt 37. The motor 35 also drives the drain pump 40.

Water is admitted to the chamber 10 through an inlet 41 which is connected through line 42 to an inlet connection 43, a solenoid-operated valve 44 being interposed in the line 42. The inlet connection 43 is connected to a suitable source of hot water.

Drainage is effected through a drain opening 45 connected by a line 46 to a solenoid-operated drain valve 49 which is integral with the drain pump 40. A discharge line 47 leads to the discharge connection 48 which is connected to a suitable sewer line. The maximum water level in the chamber 10 may be controlled by a pressuresensitive, diaphragm-operated switch 39 which opens into the bottom of the chamber 10. At a given pressure of the" free water within the chamber 10, the switch 39 is actuated to break a circuit to the solenoid-operated inlet valve 44. The switch 39 is, of course, adjusted so that the actuating pressure is that pressure which obtains when the water in the chamber has reached the desired maximum level.

manually started timer switch 50 which automatically.

controls the starting, stopping and direction of the motor 36, the energization and deenergization of the drain valve 49, and the cnergization of the inlet valve 43. Timer control switches-of the type of the switch 50 are well known to the appliance industry.

Suitably supported within the chamber and extending underneath the impeller 30 from one side to the other is a screen 60. The screen is preferably dished so as to both be suspended in spaced relation between the bottom of the impeller and the chamber deck 12 and to extend upwardly on either side to a point above the sump water level.

As outlined previously, the smooth, relatively turbulence-free action of my impeller requires a much shallower bight than do conventional impellers, my impeller displacing a considerable volumeof sump water, so that I am able to minimize the total amount of wash water required by minimizing the amount of idle" sump water which must be maintained during each moment of washing operation. This advantage of my impeller is fully exploited by dishing or depressing the deck 12 so as to further reduce the amount of water necessary to keep the impeller sufliciently immersed during washing operation. Because a significant part of the cost of operating a dishwasher is the expense of heating the water used by it, this feature affords a real economy in that it reduces the amount of hot water used in washing operation. In the appended claims, the term concave includes such a dished or depressed shape of the lower deck, whether such dishing or depression is in the form of a smooth curve or in the form of a series of sharply defined downward steps or a combination of the two. The screen" I have disclosed prevents the relatively small amount of wash water I employ from being loaded up with waste particles washed from the ware and allows full advantage to be taken of my shallow-bight impeller. The screen is so designed as to be automatically purged upon draining of the washing chamber. The large area of screening obtained by passing the screen under the impeller also assures that the volume of water flow per unit area of screen is relatively low so that any temporary clogging of given areas of the screen is of no consequence. The fact that my impeller is spaced from the bottom of the washing chamber makes it possible to provide this large area of screening despite the fact that there is only a relatively shallow body of sump water at the bottom of the washing chamber.

The ware to be washed is positioned on suitable racks 70 above and on' either side of the impeller 30. The racks 70 are preferably so arranged that they minimize interference with water or air thrown from or circulated by the impeller. Since my smooth impeller requires no guard screen, the inertia of thrown water is unimpeded by obstructions, as fully disclosed in application Serial No. 137,509 referred to above. It will be apparent that during washing operation practically all waste particles that are washed oif ware held in the racks 70 fall or are carried by return water into the water sump outside the screen 12. These particles are then trapped on the outer side of a first half of the screen as water is drawn in through that half of the screen by the impeller. At the same time, particles previously trapped on the other half of the screen (when the impeller was rotating in the opposite direction) are freed. Finally, when the chamber is drained, the direction of water flow through all the screen is outward (downward) and the waste particles on the outer (under) side of the screen are thereby carried off with the drain water.

Relatively light waste particles may tend to be trapped in suds floating on the surface of the sump water and thus :0 agglomerate at the water line of the screening or to ac carried over the screening by piling up of suds. This tendency is overcome by the action of the reversible im- 4' peller 30. As schematically shown in Figures 3 and 4, the impeller throws water downwardly toward the screen waterline on each side of the impeller, on one side when it is rotating in one direction and on the other side when it is rotating in the other direction. This downward throw of water scavenges the suds and drives the light particles below the water line where the majority of them are thereupon carried to underwater portions of the screen by the predominant recirculating current which is flowing in through the screen. Upon drainage, purging of these plarticles, along with the other heavier particles, takes p ace.

Many waste particles will be heavy enough to settle directly to the bottom of the sump during washing operation and to thus avoid all contact with the screen. This sedimentation feature of my invention further reduces and simplifies the problems of loading up and screen clogging outlined above, in that such heavy particles are disposed of upon drainage without having had any contact with the screen whatsoever.

Additional screening in the form of perforated plates 61 may be supported below the screen 60, as illustrated in Figures 1, 3 and 4, to prevent clogging of the drain line by unusually bulky waste particles, such as pieces of bone or paper wrappings that may have inadvertently been left on ware placed in the machine for washing. To allow drainage of all normal waste particles, the plates 61 are waste is caught in these plates, they may be easily cleared of such waste upon removal of the ware from the machine at the conclusion of thecycle of operation.

The schematic showing of racked dishware in Figure 1 illustrates how each piece of ware held within the washing chamber is subjected to direct water and air impingement from two dilferent directions, depending on the direction of rotation of the impeller 30. Thus, Washing and drying effectiveness of a wholly new order is attained through the provision of the reversible smooth impeller because each piece of ware to be washed is subjected from two different directions to impinging wash water thrown directly from the impeller without intervening guard screens or other inertia-dissipating obstacles.

The bi-directional spray attainable with my reversible smooth roll impeller makes possible the provision of a detergent storing and discharge device that requires no,

additional special mechanical linkages or electric central circuits whatsoever to automatically discharge detergent at a desired time after initiation of a washing cycle. My detergent storing device comprises any suitable baflle', such as the bathed container 80, which is selected with respect to the spray patterns caused by rotation of the impeller 30 in alternate directions. Detergent 81 remains dry within the container when the impeller is rotated in a first direction, as in Figure 3, and the detergent is wetted and washed out of the container when the impeller is rotated in a second direction, as in Figure 4. Thus, if there is to be pre-wash operation of the washer, the preset control cycle is arranged so that rotation of the impeller during such pre-wash operation will be inthe direction shown in Figure 3, and initial rotation of the impeller during the subsequent wash operation will be in the direction shown in Figure 4. The detergent will thus remain unused during the pre-wash operation and will automatically be released or washed out into the chamber 10 at the initiation of the wash operation. For

case of loading, the container 80 maybe pivotally supported on the lower front flange 20, as shown in Figure 2, so that. it may be turned to the dotted line position which extends from leads 91 along the sides and across one end of the impeller 30. Proper sequential ener' gization of this heating element during a complete cycle of operation may be controlled by the timer switch 50.

The preferred location of the heating element 90 in relation to the impeller 30 is seen most clearly in Fig- 1 ures 3 and 4. Fluid adjacent the roll 30 tends, perhaps due to the Bernoulli effect, to cling to the surface of the rotating roll until it attains suflicient velocity to escape tangentially from the roll. Fluid drawn in toward the roll is thus caused to pass smoothly and rapidly over on alternatesides of the washing chamber 10. In this manner, for a givenheat input, maximum water and air temperatures at the surface of the ware are attained. The time required for both washing and drying operations is thereby substantially reduced.

Manyvariations in the disclosed invention may suggest themselvesto those familiar with appliance design, in-

both sides of the heating element 90 before being car-' ried on up around the roll for distribution into the chamber 10. During washing operation, this arrangement provides for highly effective heating of the wash water; during drying operation, equally efiective heating of dry air drawn in through the vent slot 26 is afforded.

The superior circulation pattern of drying air which I ratus further negatives any possibility of smooth-predominantly laminar flow of the overall pattern throughout the washing and drying chamber in which theware is racked. Such predominantly laminar flow is achieved by the present invention.

eluding some who may be diligent to appropriate to their Q own advantage the benefits of my invention.

Accordingly, the rights conferred on me by the patent laws are not to be rendered nugatory by restricting my invention to the specific embodiment-disclosed but are to be 1 given reasonable effectby fair construction ofjthe following claims. a

What is claimed is:

1. A dishwashing machine comprising a washing chamber, rack means in said chamber, rotatable water slinging means in said chamber,fsaid water slinging means having an outer periphery of substantially constant radius said water slinging means extending transversely across said chamber, means to supply water along the length of in any given plane of rotation,- the axis of rotation ofsaid water slinging means to scour ware supported in said grack means, heating means extending longitudinally along the surface of said waterslinging meansin .spaced relation therewith,means to successively rotate said water :slinging means in a first direction whereby water flowing past said heating meansis thrown in one tangential direc tion directly from said water slinging means to ware sup- Air circulation in the present invention is particularly eflicient and effective in that each longitudinal increment of my impeller acts as an impeller for the particular plane of the drying chamber in which it lies and for adjacent planes. This holds true throughout the impeller length. Accordingly, blocking of air movement by racked dishware is minimized. A crude but graphic analogy is the comparison of an incandescent light bulb and a fluorescent tube. The light from the bulb can be blocked with two hands; the light from. the tube is diminished only slightly by attempting to block it with two hands. Similarly, a normal amount of racked ware very significantly blocks air movement from a conventional impeller, but air moved in accordance with my invention is impeded to a much lesser degree.

It should be noted that my reversible impeller can circulate air equally effectively in two directions. This is particularly significant in that it enables heat to be selectively concentrated on one side or the other of the washing anddrying chamber (the side towards which the roll rotates upwardly), so that for a given heat input each piece of ware may be subjected to higher drying temperatures than is possible in conventional structures which cannot provide a reverse pattern of flow. Even in the one direction in which they rotate, bladed or scoop type impellers cannot efiect heat concentration because the turbulent scooping or fanning action of such structures will not permit such concentration.

In my application Serial No. 137,509 referred to at the beginning of this specification, I disclosed that the included angle of water thrown from my smooth impeller could be controlled by directing vanes extending parallel to the impeller surface.

peller 30 much the same effect can be attained without the use of directing vanes. This directional selectivity enables me to exploit my heating element 90 to the fullest advantage. As impeller-deck spacing is decreased, the included angle of fluid thrown by the impellertends to become limited to the side of the chamber 10 towards I have discovered that by reducing the spacing between the deck 12 and the im-.

ported in said racks and in a second direction whereby water flowing past said heating means is'thrown in an- I other tangential direction directly'from said water slinging means to ware supported in said racks.

2. A dishwasher comprising a chest, a horizontal substantially smooth generallycylindrical impeller extending transversely-across said chest, rack means in said chest, journal means for supporting said impeller, means to maintain -'a maximum water level in said chest below said rack means and the'axis of said journal'means and to maintain said impeller sufiiciently submerged in said water to produce a scouring throw of water' upon rotation of said impeller, 'at least one heating rod extending below said water level longitudinally along the surface of said impeller in spaced relation therewith, means to successively'rotate said impeller in a first direction whereby water drawn past said heating rod is thrown in one tangential direction directly from said impeller to ware supported in said racks and in a second direction whereby water drawn past said heating rod is thrown in another tangential direction directly from said impeller to ware supported in said racks.

3. A heat transfer mechanism for heating and moving a fluid comprising a substantially smooth generally cylindrical impeller, a hot body extending along the surface of said impeller in spaced relation therewith, said hot body being immersed in said fluid, means to rotate said impeller through said fluid whereby said fluid will be drawn over said hot body and will be further translated by said impeller.

4. A blower for heating and moving a fluid comprisrotatable impeller means in said chamber, said impeller which the impeller 10 is upwardly rotating. By reversing means having an outer periphery of substantially constant radius in any given planeof rotation, the axis of rotation of said impeller means extending transversely across said chamber, means to supply a concentration of heat within said chamber, and means to rotate said impeller to distribute the heat through said chamber around a single tion of heat within said chamber, and means to rotatev said impeller to distribute the heat through said chamber around a single annular path of air circulation extending culation with the majority of heat concentrated on the side of said chamber opposite to said one side.

8. In a dishwasher comprising a chamber in which dishware is washed and dried, apparatus for drying washed dishware within said chamber, said apparatus comprising a horizontal" substantially smooth generally cylindrical impeller extending transversely across said chamber, said cylindrical impeller being rotatably mount- .ed within said chamber, means to supply a concentration of heat adjacent to the surface of said impeller along the length thereof, means to rotate said impeller in a first direction to distribute the heat through said chamber around a single annular first path of air circulation with through all the unoccupied interior of said charnber,

which path has a width equal to the length ofasaid impeller.

7. In a dishwasher comprising a chamber in which dishware is washed and dried, apparatus for drying washed dishware within said chamber, said apparatus comprising rotatable impeller means in said chamber, said impeller means having an outer periphery of substantially constant radius in any given plane of rotation, the axis of rotation of said impeller'means extending transversely across said chamber, means to supply a concentration of heat adjacent to the surface of said impeller means along the length thereof, means to rotate said impeller in a first direction to distribute the heat through said chamber around a single annular first path of air circulation with the majority of heat concentrated on one side of the chamber, and means to rotate said impeller in a second direction to distribute the heat through said chamber around a single annular second path of air cirthe majority of heat concentrated on one side of the chamber, and means to rotate said impeller in a second direction todistribute the heat through said chamber around a single annular second path of air circulation with the majority ofheat concentrated on the side of said chamber opposite to said one side.

References Cited in the file of this patent UNITED STATES PATENTS 601,275 Ping Mar. 29, 1898 1,180,471 Carson Apr. 25, 1916 1,296,315 Phillips, Mar. 4, 1919 1,439,823 Kaufmann Dec. 26, 1922 1,462,363 Christensen July 17, 1923 1,919,646 Woolhouse July 25, 1933 2,237,209 Arnold Apr. 1, 1941 2,258,215 Paulson Oct. 7, 1941 2,365,483 Mode Dec. 19, 1944 2,698,626 1955 Rumbaugh Ian. 4,

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