Ice maker

Information

  • Patent Grant
  • 6223550
  • Patent Number
    6,223,550
  • Date Filed
    Friday, February 4, 2000
    25 years ago
  • Date Issued
    Tuesday, May 1, 2001
    23 years ago
Abstract
An ice maker includes a mold and an auger. The mold has at least one cavity with a bottom surface, and is configured for containing water therein for freezing into ice. The auger has a shaft with at least one flight attached thereto, the shaft including a top end and a base end with the base end being rotatably mounted in the bottom surface of the at least one mold cavity. The shaft extends substantially vertically through the mold cavity and is configured to rotate and thereby push the ice out of the mold cavity. The shaft and/or at least one flight has an inward taper in a direction heading from the base end to the top end of the shaft.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to freezers, and, more particularly, ice-making devices.




2. Description of the Related Art




The freezer portion of a refrigeration/freezer appliance often includes an ice cube maker which dispenses the ice cubes into a dispenser tray. A mold has a series of cavities, each of which is filled with water. The air surrounding the mold is cooled to a temperature below freezing so that each cavity forms an individual ice cube. As the water freezes, the ice cubes become bonded to the inner surfaces of the mold cavities.




In order to remove an ice cube from its mold cavity, it is first necessary to break the bond that forms during the freezing process between the ice cube and the inner surface of the mold cavity. In order to break the bond, it is known to heat the mold cavity, thereby melting the ice contacting the mold cavity on the outermost portion of the cube. The ice cube can then be scooped out or otherwise mechanically removed from the mold cavity and placed in the dispenser tray. A problem is that, since the mold cavity is heated and must be cooled down again, the time required to freeze the water is lengthened.




Another problem is that the heating of the mold increases the operational costs of the ice maker by consuming electrical power. Further, this heating must be offset with additional refrigeration in order to maintain a freezing ambient temperature, thereby consuming additional power. This is especially troublesome in view of government mandates which require freezers to increase their efficiency.




Yet another problem is that, since the mold cavity is heated, the water at the top, middle of the mold cavity freezes first and the freezing continues in outward directions. In this freezing process, the boundary between the ice and the water tends to push impurities to the outside of the cube. Thus, the impurities become highly visible on the outside of the cube and cause the cube to have an unappealing appearance. Also, the impurities tend to plate out or build up on the mold wall, thereby making ice cube removal more difficult.




A further problem is that vaporization of the water in the mold cavities causes frost to form on the walls of the freezer. More particularly, in a phenomenon termed “vapor flashing”, vaporization occurs during the melting of the bond between the ice and the mold cavity. Moreover, vaporization adds to the latent load or the water removal load of the refrigerator.




Yet another problem is that the ice cube must be substantially completely frozen before it is capable of withstanding the stresses imparted by the melting and removal processes. This limits the throughput capacity of the ice maker.




What is needed in the art is an ice maker which does not require heat in order to remove ice cubes from their cavities, has an increased throughput capacity, allows less evaporation of water within the freezer, eases the separation of the ice cubes from the auger and does not push impurities to the outer surfaces of the ice cubes.




SUMMARY OF THE INVENTION




The present invention provides an ice maker which, without heat, mechanically breaks the bond between the ice cubes and the mold cavities before the water is completely frozen. This method of breaking the bond increases throughput, conserves energy and allows the ice cubes to freeze on the outside first and continue freezing in an inward direction. By eliminating the melting procedure, the ice maker substantially reduces vaporization of water within the freezer, which is further reduced by sealing the water in the mold cavities from the ambient air.




The invention comprises, in one form thereof, an ice making apparatus including a mold having a cavity with a bottom surface. The mold cavity is configured for containing water therein for freezing into ice. An auger extends substantially vertically through the mold cavity. The auger is configured for rotating to thereby push the ice out of the mold cavity. The auger includes a rotatable surface at least partially defining the bottom surface of the mold cavity. The rotatable surface includes at least one ramp configured for lifting the ice off of the bottom surface of the mold cavity.




The invention comprises, in yet another embodiment thereof, an ice maker which includes a mold and an auger. The mold has at least one cavity with a bottom surface, and the at least one mold cavity is configured for containing water therein for freezing into ice. The auger includes a shaft having a longitudinal axis and having at least one flight attached thereto, the shaft including a top end and a base end with the base end being rotatably mounted in the bottom surface of the at least one mold cavity. The shaft extends substantially vertically through said at least one mold cavity and is configured to rotate and thereby push the ice out of said at least one mold cavity. The shaft and/or at least one flight has a radius that decreases relative to the longitudinal axis in a direction heading from the base end to the top end of the shaft and thereby has a radially inward taper in that direction.




An advantage of the present invention is that heat is not needed in order to break the bond between the ice cubes and their mold cavities, thereby conserving energy and reducing operational costs.




Another advantage is that, since the mold cavities are not heated, and since the ice cubes are not completely frozen before being removed from their cavities, the time spent freezing the water in the cavities is reduced, and the throughput rate is increased.




Yet another advantage is that, since the mold cavities are not heated, the water freezes from the outside in, thereby pushing impurities to the inside of the cube, where they are less conspicuous and do not plate out on the mold surface.




A further advantage is that, since the step of melting the outer surface of the ice is eliminated, and since the water is sealed from ambient air while freezing, vaporization of the water is greatly reduced, resulting in less frost on the wall of the freezer and less water that the refrigerator must remove.




A still further advantage is that the provision of at least one inward taper allows an ice cube to automatically become separated from at least a portion of the auger upon movement of the ice cube in an output direction. Even though the ice cube has an inward taper to match that of the auger, the inner diameter of the ice cube at a given location therein has its own specific value. Meanwhile, the diameter of at least a portion of the auger adjacent to that given location, the diameter of the shaft and/or the outer diameter of the at least one flight, continually decreases relative to the inner diameter of that given location as the ice cube is moved in the output direction. Consequently, since the contact area per unit length between the auger and an ice cube decreases as the ice cube moves along the auger, the friction per unit length therebetween also decreases.











BRIEF DESCRIPTION OF THE DRAWINGS




The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:





FIG. 1

is a top view of the mold and auger of the ice making apparatus of

FIG. 1

;





FIG. 2

is a front, partially sectional view of one embodiment of an ice making apparatus of the present invention;





FIG. 3

is a front, enlarged, fragmentary, partially sectional view of another embodiment of an ice making apparatus of the present invention;





FIG. 4

is a front, partially sectional view of yet another embodiment of an ice making apparatus of the present invention;





FIG. 5

is a side view of another embodiment of an auger for the ice making apparatus of the present invention;





FIG. 6

is an end view of the auger shown in

FIG. 5

; and





FIG. 7

is an exaggerated, fragmentary, sectional view of the auger shown in

FIGS. 5 and 6

as viewed along line


7





7


of FIG.


6


.




Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.











DETAILED DESCRIPTION OF THE INVENTION




Referring now to the drawings, and particularly to

FIG. 2

, there is shown an ice making apparatus


10


including a mold


12


, a rotatable auger


14


, a housing


16


and a drive mechanism


18


. For ease of illustration, ice making apparatus


10


is shown as including only a single mold


12


. However, it is to be understood that ice making apparatus


10


may include multiple molds


12


for delivering multiple ice cubes.




Mold


12


includes a front wall


20


, a back wall


22


, a base


24


and a side wall


26


. Another side wall


27


(

FIG. 1

) is also included in mold


12


, but is not shown in the partially sectional view of FIG.


2


. An inner surface


28


of each of perimeter walls


20


,


22


,


26


and


27


is slanted outwardly at an angle Θ relative to a vertical direction indicated by dotted line


30


. Angle Θ can be approximately between 1° and 5°, and is preferably approximately 3°. Walls


20


,


22


,


26


and


27


retain water within a cavity


32


of mold


12


. A level of the water's surface is indicated with a horizontal line


34


shown in an alternative embodiment in

FIG. 3. A

top edge


36


of side wall


26


is visible in

FIG. 2

, and is at the same vertical level as a top edge of side wall


27


and the respective top edges


38


and


40


of front wall


20


and back wall


22


. Auger


14


includes a shaft


42


and a lifter


44


which are fixedly joined together by set screws


46


. It is also possible for shaft


42


and lifter


44


to be formed together as a one-piece, monolithic auger. Auger


14


, including both shaft


42


and lifter


44


, rotates about a longitudinal axis


48


which extends vertically through the center of cavity


32


. Shaft


42


includes a continuous series of spiraling flights


50


, each of which is spaced approximately 0.2 inch from each vertically adjacent flight


50


. That is, there are five flights


50


per vertical inch.




Lifter


44


includes a rotatable surface


52


and a shank


54


having threads


55


. As best seen in

FIG. 1

, surface


52


is substantially circular with a diameter of approximately 1.0 inch. Surface


52


partially defines a bottom surface


56


of cavity


32


, with base


24


of mold


12


defining the remainder of bottom surface


56


. Rotatable surface


52


includes two ramps


58


and


60


, each of which forms one half of surface


52


. A bottom


62


of ramp


58


is adjacent to a top


64


of ramp


60


. Conversely, 180° away, a top


66


of ramp


58


is adjacent to a bottom


68


of ramp


60


. Each of ramps


58


and


60


has a drop of 0.1 inch in a clockwise direction as viewed in FIG.


1


. Thus, each of ramps


58


and


60


has a slope of 0.1 inch per half rotation, or 0.2 inch/rotation, matching the slope of flights


50


. Further, the vertical level of surface


52


along any radius is constant. For example, the vertical level of surface


52


alone radius


70


, half way down ramp


60


, is 0.05 inch above bottom


68


of ramp


60


and 0.05 inch below top


64


of ramp


60


. Housing


16


supports mold


12


and contains drive mechanism


18


. Housing


16


includes an internally threaded cup


72


having threads


74


which interface with threads


55


of shank


54


.




Drive mechanism


18


functions to rotate auger


14


through an output shaft


76


which is coupled with shank


54


. Drive mechanism


18


may be in the form of an electrical motor, for example.




In operation, cavity


32


is filled with water to an appropriate level, such as that of the illustrated water surface


34


, by any suitable method. The air surrounding both ice making apparatus


10


and the water is cooled below 32° F. by refrigeration such that the water at least partially freezes. Mold


12


and auger


14


are maintained below freezing and thus absorb heat from the water that is adjacent to these parts in cavity


32


. Ice first forms in the areas of cavity


32


that are adjacent mold


12


and auger


14


to thereby form a shell


77


surrounding the remaining water


78


in cavity


32


.




Once an outer shell


77


of ice has formed in cavity


32


, drive mechanism


18


can be used to lift the ice out by rotating auger


14


in a clockwise direction, as viewed in FIG.


1


. Threaded cup


72


of housing


16


functions to allow auger


14


to rotate, while at the same time holding down auger


14


.




During the freezing process, a bond forms between the ice and mold cavity


32


. More particularly, a bond forms between the ice and each of bottom surface


56


and walls


20


,


22


,


26


and


27


. Before the ice cube can be lifted out of cavity


32


, these bonds must be broken while, at the same time, not breaking the relatively fragile outer shell


77


of the ice cube.




As auger


14


rotates, ramps


58


and


60


function as shearing devices which break the bond between the ice and bottom surface


56


of cavity


32


. Since the ice cube is approximately square-shaped, it cannot rotate within cavity


32


. Ramps


58


,


60


and flights


50


work together to lift the ice upward at a same rate. By ramps


58


,


60


and flights


50


operating conjunctively, the total upward force exerted on the ice cube is spread out over a greater surface area of the cube, thereby minimizing the chances of breaking the ice cube. The shearing and upward forces exerted on the ice cube by ramps


58


and


60


as they rotate, as well as the additional upward force exerted by flights


50


, is enough to break the bonds between the ice and mold


12


. The surface finish on inner surface


28


and rotatable surface


52


is also critical in shearing the bond between the ice and mold cavity


32


.




After one-half rotation of auger


14


, flights


50


and ramps


58


,


60


have lifted the ice approximately 0.1 inch from its original position and the ice loses contact with rotatable surface


52


. As auger


14


continues to rotate, flights


50


push the ice cube further upward along shaft


42


.




Since there are five flights


50


per vertical inch on shaft


42


, it follows that five full rotations of auger


14


will raise the ice by approximately one inch such that the bottom of the ice cube is approximately at the same vertical level as the top edges


36


,


38


and


40


of walls


20


,


22


and


26


, respectively. At this vertical level, or at any other level at which the bottom of the ice cube is above filling level


34


, cavity


32


is again filled with water to the level of


34


.




As the newly inserted water in cavity


32


begins the freezing process, the ice cube


81


disposed immediately above on shaft


42


begins to freeze more completely. Stress cracks which may have formed in the ice cube due to the forces of auguring are again filled with water seeping in from the middle of the cube. After the water in cavity


32


has partially frozen, the auguring process is recommenced to thereby push the newly formed second cube


83


upward along shaft


42


. As the second cube


83


makes contact with the first cube


81


, the first cube


81


is pushed further up and off of a top


79


of auger shaft


42


. As the first cube


81


comes off of shaft


42


, the inner radial walls


85


defining the center through hole


87


in the cube lose the support of shaft


42


. Since the first cube may still not be completely frozen at this point, the water inside the cube may expand and rupture the inner radial walls


85


, thereby at least partially filling in the center through hole


87


. After the first cube has completely slid off of auger


14


, it can then drop into a dispenser tray (not shown) below apparatus


10


.




In other embodiments, an extension wall


80


, a deflector


82


, a cube guide wire


84


, a cooling device


86


and/or a fin


88


may be included in the ice making apparatus. Extension wall


80


is attached to top edge


40


of back wall


22


. Extension wall


80


serves to prevent the ice cubes from rotating along with auger


14


as the cubes progress along the upper portion of shaft


42


. Thus, an ice cube can be released off of top


79


of shaft


42


, even without the benefit of a second cube below it to provide an upward pushing force.




Deflector


82


is attached to a top edge


90


of extension wall


80


. Deflector


82


serves to direct the ice cubes in a predetermined direction, i.e., over front wall


20


, as the cubes come off of shaft


42


. Thus, the ice cubes may be directed into a dispenser tray, for example, that is positioned below front wall


20


.




Cube guide wire


84


is an elongate guiding element attached to top


79


of auger shaft


42


. Cube guide wire


84


is received in the center through hole in the ice cube as the cube comes off of shaft


42


. Cube guide wire


84


slidingly guides the ice cube in a predetermined direction, indicated by arrow


92


, possibly towards a dispenser tray.




Cooling device


86


is in the form of a refrigeration coil


94


and a tube


96


extending through back wall


22


and extension wall


80


of mold


12


. Thus, cooling device


86


directly contacts and directly cools mold


12


, rather than indirectly cooling mold


12


by cooling the air surrounding mold


12


. The direct cooling of mold


12


ensures that the water adjacent to mold


12


in cavity


32


freezes first, thereby forming an outer shell of ice surrounding an inner core of water.




Fin


88


extends vertically along inner surface


28


of back wall


22


. Fin


88


functions to increase the surface area of inner surface


28


that is in contact with the water in cavity


32


. The increased surface area provides improved heat transfer between mold


12


and the water, and results in quicker freezing of the water. If the mold cavity is substantially circular, fin


88


has the additional advantage of preventing rotation of the ice as auger


14


rotates.




In one embodiment, each of perimeter walls


20


,


22


,


26


and


27


extends vertically approximately to the vertical level of top


79


of auger shaft


42


, as indicated at


98


. As is evident in

FIG. 3

, an inner surfaces


100


of the extended portions of perimeter walls


20


,


22


,


26


and


27


do not continue the outward flare of inner surfaces


28


. Rather, inner surfaces


100


are oriented substantially vertically, i.e., parallel to shaft


42


.




In operation, if cavity


32


is filled with water substantially to the level of top edges


36


,


38


and


40


, and a top of a first cube


81


is substantially adjacent to level


98


when a second cube


83


is being formed in cavity


32


, the first cube


81


can substantially seal off cavity


32


from the ambient air outside of mold


12


. Thus, the water in cavity


32


can be prevented from vaporizing and thereby forming frost on the walls (not shown) of the freezer in which mold


12


is located. That is, the extension of perimeter walls


20


,


22


,


26


and


27


to the level of


98


allows the first ice cube


81


to seal cavity


32


from the ambient air after cavity


32


has been refilled with water, thereby substantially inhibiting the formation of frost within the surrounding freezer.




In yet another embodiment, ramps


58


and


60


are replaced with another ice lifting device in the form of actuators


102


. Actuators


102


push up on the bottom of the ice cube in order to break the bond between the ice and rotatable surface


52


of auger


14


. Actuators


102


may be powered pneumatically, hydraulically or electrically, such as by drive mechanism


18


, for example. The vertical rise of the ice-interfacing, top surface


104


of actuators


102


can be synchronized with the rotation of auger


14


in order to match the vertical rise of the ice as provided by flights


50


.




In the embodiments shown, perimeter walls


20


,


22


and


26


of mold cavity


32


are arranged in a non-circular shape. However, it is to be understood that it is also possible, in an alternative embodiment, for perimeter walls


20


,


22


,


26


and


27


to form a circular shape. In this alternative embodiment, auger


14


is eccentrically disposed, i.e., horizontally displaced from a the center of mold cavity


32


, in order to prevent the ice from rotating in mold cavity


32


along with auger


14


.




In another embodiment (FIG.


4


), a shaft


106


includes an internal heat pipe


108


with a valve fill hole


110


. A fluid within heat pipe


108


absorbs heat in cavity


32


and vaporizes. The vapor rises in heat pipe


108


, releases the heat near top


109


of shaft


106


, condensates, and falls back into cavity


32


where the cycle repeats. Thus, the absorption of heat from cavity


32


by heat pipe


108


promotes the radially inward freezing of ice cube


81


. As such, heat pipe


108


is an active means of transferring thermal energy from cavity


32


. However, heat pipe


108


could be replaced with an auger


14


made of a material with a substantial heat transfer coefficient, thereby relying on the conductance of heat away from cavity


32


through auger


14


to chilled mold


12


to freeze ice cube


81


radially inwardly.




Drive mechanism


18


functions to rotate auger


112


through output shaft


76


which is coupled with shank


114


via a set screw


46


. An outer perimeter


116


of a lifter


118


has a clearance of approximately 0.005 inch from an inside surface


120


of a mold


122


. At a temperature of, for example, 25° F., any water which seeps in between perimeter


116


of lifter


118


and inside surface


120


of mold


122


freezes and thereby seals the gap.




A further embodiment of an auger


130


is shown in

FIGS. 5-7

. Shaft


132


of auger


130


has a single continuous flight


134


mounted thereon, for purposes of illustration. Of course, multiple flights, continuous or spaced, may instead be employed. Shaft


132


has a top end


138


and a base end


136


configured for coupling with drive mechanism


18


to rotate auger


130


. The direction from base end


136


to top end


138


constitutes an output direction


140


, the direction in which ice cube


81


is to be pushed out of mold


12


. In this embodiment, shaft


132


and/or flight


134


has an inward taper, thus becoming increasingly more narrow, in output direction


140


. The provision of at least one such inward taper allows ice cube


81


(

FIG. 3

) to automatically become separated from at least a portion of auger


130


upon movement of ice cube


81


in output direction


140


.




Both shaft


132


and flight


134


are shown to be tapered, as best shown in

FIG. 7

, the inward taper of shaft


132


being shown as angle α, and the inward taper of flight


134


being shown as angle β. Each of taper angle α and taper angle β may be between approximately 0.1° and 5°, preferably between about 0.2° and 0.8°, and more preferably about 0.5°. In achieving an inward taper of shaft


132


, maximum diameter


142


near base end


136


is greater than the minimum diameter


144


at top end


138


. Similarly, in achieving an inward taper of flight


134


, maximum outer diameter


146


near base end


136


is greater than the minimum outer diameter


148


at top end


138


. The maximum diameter in each instance should exceed the corresponding minimum diameter by between about 0.005 and 0.1 inch and preferably by between about 0.007 and 0.04 inch. For example, maximum outer diameter


146


of flight


134


near base end


136


may be about 0.33 inch and minimum outer diameter


148


thereof at top end


138


may be about 0.31 inch.




As best seen in the break-away longitudinal cross section of auger


130


(FIG.


7


), flight


134


has a radial periphery a partially rounded portion


150


. Rounded portion


150


provides less surface area for ice cube


81


to contact upon movement thereof out of mold


12


, easing separation thereof from auger


130


. Additionally, the rounding eliminates potentially sharp surfaces upon which ice cube


81


could be damaged




While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.



Claims
  • 1. An ice making apparatus, comprising:a mold including a cavity, said mold cavity having a bottom surface, said mold cavity being configured for containing water therein for freezing into ice; and a thermal transfer member mounted within said bottom surface of said mold cavity, said thermal transfer member extending substantially vertically upwardly from said bottom surface of said mold cavity, said thermal transfer member being configured to cool the water contained by said mold cavity and thereby promote the freezing thereof, said thermal transfer member being an auger rotatably mounted in said mold and extending substantially vertically through said mold cavity.
  • 2. The ice making apparatus of claim 1, wherein said auger includes a heat pipe therein, said heat pipe having a fluid therewithin for absorbing heat from the water contained by said cavity.
  • 3. The ice making apparatus of claim 1, wherein said thermal transfer member further extends below said bottom surface.
  • 4. An ice making apparatus, comprising:a mold including a cavity, said mold cavity having a bottom surface, said mold cavity being configured for containing water therein for freezing into ice; and a thermal transfer member mounted within said bottom surface of said mold cavity, said thermal transfer member extending substantially vertically upwardly from said bottom surface of said mold cavity, said thermal transfer member being configured to cool the water contained by said mold cavity and thereby promote the freezing thereof, said thermal transfer member being an auger rotatably mounted in said mold and extending substantially vertically through said mold cavity, said auger including a lifter having a rotatable surface, said rotatable surface at least partially defining said bottom surface of said mold cavity, said rotatable surface including at least one ramp configured for lifting the ice off of said bottom surface.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 09/285,283, entitled “ICE MAKER,” filed Apr. 2, 1999 now U.S. Pat. No. 6,082,121.

US Referenced Citations (17)
Number Name Date Kind
948131 Bull Feb 1910
1963842 Gay Jun 1934
2775101 Hanson Dec 1956
3196624 Reynolds Jul 1965
3274792 Weil et al. Sep 1966
3654772 Curry, III Apr 1972
3678701 Powell et al. Jul 1972
3708992 Clearman et al. Jan 1973
3896631 Morrison Jul 1975
3984996 Bright Oct 1976
4003214 Schumacher Jan 1977
4183222 Swanson Jan 1980
4355522 Gorski et al. Oct 1982
4429543 Fischer Feb 1984
4732006 Fischer Mar 1988
4901539 Garber et al. Feb 1990
5167132 Meier Dec 1992
Foreign Referenced Citations (1)
Number Date Country
351706 Mar 1921 DE
Continuation in Parts (1)
Number Date Country
Parent 09/285283 Apr 1999 US
Child 09/499011 US