US2704927A - Freezing tray arrangement - Google Patents

Description

March 29, 1955 'AR 2,704,927

FREEZiNG TRAY ARRANGEMENT Filed Aug. 2, 1951 2 Fl I. Z

Inventor: John Rayburn Carrell,

B flaw... AM

'3 His Abtor-ne s/ United States Patent FREEZING TRAY ARRANGEMENT John R. Carrell, Richland, Wash., assignor to General Electric Company, a corporation of New York Application August 2, 1951, Serial No. 239,871

3 Claims. (Cl. 62-99) My invention relates to household refrigerators and, inore particularly, to a freezing tray arrangement there- It is common practice in household refrigerators to provide a support within the evaporator or freezing compartment for holding a plurality of freezing trays. In the usual case, this support consists of a metal shelf or metal slides projecting from the sides of the compartment so as to furnish an excellent heat conduction path between the walls of the tray and the walls of the evaporator or freezing compartment. In such an arrangement the actual heat transfer involved in the freezing process is accomplished almost entirely by conduction of heat through the walls of the tray. The freezing process within the tray thus proceeds more or less from the side and bottom portions of the block towards the center and top portions. While this arrangement provides for relatively rapid freezing, it is subject to the disadvantage that the resulting ice block adheres to the walls of the tray and is frequently difficult to dislodge. In my present invention I provide a new and improved arrangement for freezing trays whereby this disadvantage of adhesion between the ice and the tray is overcome. My invention contemplates supporting the freezing trays within the evaporator or freezing compartment in such a manner that the actual freezing process proceeds substantially from the top or exposed surface of the water toward the bottom portions. In my arrangement the heat transfer necessary for freezing the water takes place almost entirely by radiation in contrast to the conventional method which utilizes conduction. As a direct result of my arrangement, the actual freezing process is effective to break the adhesion which tends to occur between the block and the walls of the tray. It is known that when water is transformed into ice, a substantial increase in volume takes place, and in my invention it is this expansion which is operative to break the adhesion between the walls of the tray and the ice block.

Accordingly, it is an object of my invention to provide a new and improved arrangement for household refrigerators in which freezing trays are removably supported within a freezing compartment so as to facilitate freezing from the top or exposed surface of the water downward.

It is another object of my invention to provide a freezing compartment of a household refrigerator with removable freezing tray supporting elements whereby if maximum ice production is not desired, the individual trays together with their supports may be removed from the compartment.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In carrying out the objects of my invention, 1 mount the freezing trays immediately below a horizontal refrigerated wall. The trays are supported from this wall by removable members of a material of low heat conductivity for minimizing transfer of heat from the trays themselves. Accordingly, heat is removed from the water in the trays primarily from the top surface thereof, and the water freezes primarily from the top downwardly.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is a fragmentary front view of the top portion of a household refrigerator cabinet with a portion of the door cut away so as to show the interior arrangement; Fig. 2 is a cross-sectional view along the line 22 of Fig. 1; 1 1g. 3 shows a type of freezing tray which may be utilized in conjunction with my invention; and Figs. 4, 5 and 6 are cross sections through one of the receptacles or molds of a freezing tray, illustrating stages in the freezing of ice blocks.

In Fig. 1, I have shown the upper portion of a household refrigerator having a cabinet 1 which is provided with a door 2 hinged for opening movement so as to provide access to the interior portions of the refrigerator cabinet. The interior portion of the refrigerator cabinet 1 includes a freezing compartment 3 which is defined by an inner liner element 4. This freezing compartment has a top wall 5 which is disposed in a substantially horizontal plane. Heat is extracted from the freezing compartment 3 through refrigerant tubing 6 which is mounted in heat exchange relationship upon the upper or unexposed surface of the top wall 5. The tubing 6 is supplied with refrigerant by a conventional condensing unit (not shown).

The temperature of the wall 5 and the temperature within the freezing compartment 3 is maintained at a point substantially below the freezing point of water during normal operation of the refrigerator. On the lower or exposed surface of the top wall 5, I have mounted a plurality of channels or tracks 7 which serve as supporting guides for racks 8 which in turn support freezing trays 9 in a horizontal position below and spaced from the top wall 5 in a manner to be described below.

Fig. 2 shows the manner in which the channels or tracks 7 are secured to the top wall 5 of the freezing compartment. In a preferred form of my invention, the channels or tracks 7 are secured in place by means of a plurality of screws 10. Obviously, any other satisfactory method, such as brazing or welding, could be employed to secure the channels or tracks in position.

Referring again to Fig. 1, the channels or tracks 7 provide a trackway which is adapted to receive upper flange portions 11 formed on the racks 8. The flanges 11 are therefore adapted to have a sliding engagement with the channels 7. The lower portions of the racks 8 are provided with laterally extending flanges 12 which in turn serve as supporting surfaces for the freezing trays 9. This arrangement permits the freezing trays 9 to be supported in a horizontal position a short distance below the lower or exposed surface of the top wall 5. By virtue of the fact that this top wall 5 is refrigerated, the lowest temperatures Within the compartment 3 exist adjacent the lower or exposed surface of this wall. In other words, with the trays 9 in position as shown in Fig. l, a temperature gradient will exist in the air surrounding the trays such that the top or exposed surface of the water within the tray will lose its heat more rapidly than the water in the bottom of the tray. This heat loss will be accomplished primarily by radiation from the top or exposed surface of the water. It is apparent, then, that the freezing of the water within the tray will proceed from the top downward. This, however, will only be true so long as there is no direct heat-conduction path existing between the tray 9 and the top wall 5. If such a heat conduction path did exist, it is obvious that the water in the bottom portions of the tray 9 would lose its heat rapidly by conduction, and the freezing process would proceed from the walls and bottom of the tray toward the center and top of the body of water. In order to prevent this result, the supporting racks 8 which cooperate with the channels 7 to suspend the freezing trays 9 in position are formed of a material of low heat conductivity. In practice I have found that polystyrene serves this purpose very well, but it is obvious that other plastics and other materials of low heat conductivity could be employed for the racks 8.

In Fig. 3, I have shown a freezing tray 9 which I utilize in my invention. This tray 9 includes a plurality of individual ice receptacles or molds 13. These receptacles or molds 13 have a hemispherical shape, but the application of my invention is not limited to receptacles of this particular configuration; for example, I have employed trays having receptacles of truncated cone cross section. The upper portion of the tray 9 is provided with outwardly extending flanges or lips 14 which, when the tray is in position within the freezing compartment 3 as illustrated in Fig. 1, rest upon the lower flanges 12 of the supporting racks 8. I have further found that the tray 9 can be conveniently formed of a plastic material although 1 do not wish to so limit my invention since I have found that a metal tray, such as bright aluminum, will atso function satisfactorily.

In Figs. 4, 5, and 6, I have illustrated the manner in which the freezing process facilitated by my invention proceeds within a mold or receptacle of the freezing tray 9. The particular mold has been filled with water and has been in position under the top wall of the freezing compartment for a short period of time in the stage illustrated in Fig. 4. During this time the upper portions of the water in the mold have lost heat by radiation from the top surface to the wall 5, and, since this heat loss occurs at a rate much faster than any loss from the bottom portions of the water through the tray 9, a much thicker layer of ice 15 is formed along the top surface of the water in the receptacle than the layer 16 adjacent the bottom surface of the receptacle.

As the freezing process continues, the water 17 trapped within the surrounding shell of ice expands, and ultimately the pressure exerted by the freezing Water causes a rupture of the surrounding ice. Since the layer 16 is much thinner than the layer 15 along the upper region of the receptacle, the rupture naturally occurs somewhere along the layer 16 at the bottom portion of the tray. This causes a pressure to be exerted forcing the partially frozen ice block upwardly from the bottom of the receptacle and causing a release of the ice block from the wall of the receptacle. The water passing through the rupture refreezes, causing a projection or bump 18 in the area of the rupture. The ice block at this stage in the freezing process is illustrated generally in Fig. 5. It can be seen from Fig. 5 that the aforementioned rupture and refreezing, again trapping the body of water 17, has resulted in the projection 18 forcing upward movement of the ice block relative to the adjacent wall of the receptacle.

As the freezing process continues, the trapped water 17 in the partially frozen block illustrated in Fig. 5 expands, and when the pressure becomes sufficiently great, it causes an additional rupture of the ice block. This rupture will normally occur in the general region of the initial rupture since the ice layer has been weakened at this point. Ultimately the entire ice block will be frozen, in the stage illustrated in Fig. 6, the ice block in this stage being, because of the upward force previously exerted, substantially free of adhesion to the wall of the receptacle. While the freezing process has been illustrated with only two intermediate stages, it will be appreciated that, in actual operation, there may be a substantial num ber of ruptures and refreezings, each effecting an upward movement of the ice block. Release of ice blocks is not an instantaneous process but occurs intermittently as pressure is periodically released by fracture of the ice walls. Hence the ice block is released and forced upwardly a number of times during the completion of the freezing process. After the ice block has been completely frozen, as illustrated in Fig. 6, manual force may be exerted, if necessary, against the ice block adjacent the outer edge thereof, as indicated at 19, so as to make the diametrically opposite portion 20 thereof project above the top of the tray for easy removal of the ice block.

In summary, it can be seen that I have provided a refrigeration apparatus with a freezing tray arrangement in which the release of ice blocks from the trays is facilitated by the actual freezing process. This I have accomplished by removably mounting the ice trays in a horizontal position slightly below a refrigerated wall, and

supporting them by removable supports formed of a material of low heat conductivity. In such an arrangement there is no direct heat conduction path between the tray itself and the refrigerated wall, and therefore the water within the tray freezes in a progressive manner primarily from the top downward. It is also possible for the user to remove both the trays and supports when ice production is not desired.

While I have shown a specific embodiment of my invention applied to a refrigerator having a freezing compartment, it is to be understood that the invention could be employed equally well in a refrigerator having no freezing compartment as such but which utilizes a horizontal plate type evaporator. I do not therefore wish my invention to be limited to the specific construction shown and described, and I intend, by the appended claims, to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerator cabinet the combination of a freezing compartment disposed within said cabinet and having a horizontally disposed top wall portion, said top wall portion having an upper surface and a lower surface, refrigerant tubing mounted in heat exchange relationship with said upper surface of said top wall portion for cooling said top wall portion, a freezing tray removably supported in a horizontal position within said freezing compartment below and in closely spaced relationship with said lower surface of said top wall portion, and supports formed of material of low heat conductivity for supporting said tray from said top wall portion, said supports being removably mounted on said top wall portion.

2. In a refrigerator cabinet the combination as set forth in claim 1 in which the removable supports are formed of a plastic material of low heat conductivity.

3. In a cabinet for refrigerators and the like, the combination of a freezing compartment disposed within said cabinet and having a horizontally disposed top wall portion, said top wall portion having an upper surface and a lower surface, refrigerant tubing mounted in heat exchange relationship with said upper surface for cooling said top wall portion and a plurality of channels secured in a spaced parallel horizontal position to said lower surface of said top wall portion, each of said channels forming a trackway, and a plurality of racks formed of material of low heat conductivity having upper and lower flange portions, said upper flange portions having sliding engagement with said trackways of said channels so as to removably support said racks, said lower flange portions engaging at least one freezing tray for removably supporting said tray below and in closely spaced relationship with said top wall portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,868,070 Newman July 19, 1932 1,898,706 Allyne Feb. 21, 1933 1,973,033 Ashbaugh Sept. 11, 1934 2,037,417 Hull Apr. 14, 1936 2,217,681 Jennings Oct. 15, 1940 2,218,724 Rudd Oct. 22, 1940 2,297,581 Peltier Sept. 29, 1942 2,302,044 Mochel Nov. 17, 1942 2,322,626 Gerhard June 22, 1943 2,438,466 Tobey Mar. 23, 1948 2,457,009 Tanner Dec. 21, 1948 2,469,067 Follin May 3, 1949 2,516,586 Peltier July 25, 1950

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