US2074700A - Cooling unit for refrigeration purposes - Google Patents

Description

March 23, 1937. 2,074,700

COOLING IlJNIT REFRIGERATION PURPOSES I A. s. LIMEERT Filed Nov. 21, 1932 INVEIT R:

mAT-roRNEY.

Marh 23, 1937. A. s. LIMPE RT COOLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1932 7 Sheets-Sheet 3 INVENT'RI' flZATTORNEY.

March 23, 1937. A. s. LIMPERT 2,074,700

COOLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1952 7 Sheets-Sheet 4 Q 7 lNV T9R:.

' .fl ATTORNEY.

MarcF 23, 1937. A.IS..LIMPERT COCLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1952 7 Sheets-Sheet 5 I V INVE T -3 5 Q MXW I BY fl d'ATTORNEY.

March 23, 1937. A. s. LIMPERT CObLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1932 7 Sheets-Sheet 6 March 23,1937. A, s, LIMPERT 2,074,700

COOLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1932 '7 Sheets-Sheet 7 ZATTORNEY.

Patented Mar. 23,1937

UNITED STATES PATENT OFFICE COOLING UNIT FOR REFRIGERATION PURPOSES Application November 21, 1932, Serial No. 643,695

4 Claims.

This invention relates to apparatus which is peculiarly suited for use as a cooling unit of an automatic refrigerator wherein an efficient, sturdy, compact, cheap and attractively designed unit is a matter of prime consideration. The

further objects of the invention are the provision of a construction and a method of making same whereby such unit can be formed from ferrous or non-ferrous metals as a result of either a casting, a die-stamping or pressure diecasting operation and which unit readily lends itself to being finished in enamel. Other objects of the invention are hereinafter set forth.

Heretofo-re it has been proposed to cast a tube of high conductivity, such as copper, for example, in a wall of metal of lower melting point, such for example as type metal, or other zinc alloys or even aluminum, but while tanks having such coils cast in the walls thereof are quite efficient as cooling units, nevertheless, there are some objections, such as the difficulties of cast-- ing, the susceptibility of tubing such as copper, to form scale on the inside thereof during the casting operation, which scale tends to often lodge in valve-seats and bearings and other portions of a mechanical refrigerating machine and also the tendency to form air pockets between the coil and the metal wall in which the same is embedded due to the difference in the coefficients of expansion of the two metals. Also such cooling units cannot be enameled satisfactorily, since in the enamelling operations the temperatures are so high as to in many cases burn the coil besides forming scale as aforesaid, therein. Neither isit considered practicable at the present time to form such tanks of ferrous metal, such as steel or iron, as it is extremely difficult, if not impossible, to satisfactorily cast a coil therein unless the coil is of some expensive high melting point steel or other alloy and furthermore, the forming of such a coil is itself an extremely difficult and expensive operation.

My investigations have led to the discovery that the aforesaid objections can be effectively overcome and a cooling unit which is remarkably efficient can be constructed by following the method set forth in detail in the following description and drawings forming a part thereof.

Referring to the drawings wherein I have illustrated different embodiments of the invention Figure l is aside elevation;

Fig. 2 a rear elevation; 1

Fig. 3 is a ver i al l g tud nal section of a sectional freezing unit showing one form of the invention;

Fig. 4 is a transverse vertical section onthe line 4-4 of Fig. 3;

Figs. 5, 6 and '7 are horizontal sections on the lines 5-5, 6-% and 1-1 respectively of Fig. 3;

Fig. 8 is a longitudinal vertical section of a modification wherein the main body comprises a casting and in which all the pressure plates are internally disposed; Fig. 9 is a fragmentary detail horizontal section onthe line 9-9 of Fig. 8; and

Fig. 10 is a section on the line l0l0 of Fig. 8;

Fig. 11 is a front elevation of a still further modification having an ultra-rapid freezing compartment; Fig. 12 is a plan view, partly broken away of the same unit and Fig. 13 is a perspective view, partly cut away, of one of the small sections of the same unit.

Fig. 14 is a plan View of one of the intermediate units of Fig. 11; Fig. 15 is a detail frag-- mentary vertical section on the line |5--|5 of Fig. 14. and Fig. 16 is a vertical section, partly interrupted of Fig. 11.

Fig, 1'7 is a vertical transverse section of a still further type of unit.

Now, referring to the construction shown in the drawings, the type of unit illustrated in Figs. 1 to 3 and 6 to 8, comprises a built-up or sectional unit formed of two main castings or sections I and 2 respectively, the larger or upper one being of suflicient size to receive what is known as a pudding tray and the lower section on which it is superimposed being of a size to receive the usual cube tray. The bottom 3 of'section l and the top 4 of section 2 (Fig. 3) are virtually identical except that their position is reversed and each of the same is provided with front flanges 5 and 6 respectively. The top 1 of section I' and the bottom 8 of section 2 .are also identical but reversed in position; and these sections have substantially continuous marginal flanges 9 and II), respectively, that extend along all edges thereof, Integral cored bosses H, H and l2, [2 are formed on the sides of the casting I and 2 (see Fig. 1). The bosses II and I2 are provided with radiating fins or vanes l3, l3 and additional fins I4, M are formed on the side walls of sections I and 2. The size and number of such fins is determined according to the extent that it is desired to increase the superficial area of the unit and thereby the consequent cooling effect of such unit upon the air of the refrigerator can be regulated, thus permitting of a relatively small unit being equally serviceable either for a refrigerator of relatively small capacity or for the cooling of refrigerators of considerably larger capacity while at the same time admitting of the rapid freezing of ice cubes in trays positioned within the cooling unit proper. 5 The cooling coil [5, through which the refrigerant is circulated for the purpose of maintaining the cooling unit at the desired temperature, preferably comprises metallic tubing, preferably of lead, because of its pliability, which tubing is originally circular in cross-section and which is first bent to a predetermined loop formation, such as illustrated in Figs. 5, 6 and '7. Such looped tubing or so-called coil is then applied to the surfaces a and b and 0 (see Fig. 3), and thereafter flattened to a substantially elliptical formation by means of a dummy or master pressure plate which is forced under considerable pressure, either mechanical or hydraulic, against such coils, while they are in position on the supporting surface, until the said coils assume the flattened or elliptical cross-sectional configuration shown in Figs. 3 and 4, for example.

As shown, the coil I5 is connected at the top of the unit to the intake fitting l6 carried by a top pressure plate I! (Fig. 3) and, as shown in Fig. 5, is looped to form a circuitous path so as to effectively cover, insofar as its heat-exchange effect is concerned, the top face 0 of the upper unit. From the space d between the top of section 2 and pressure plate 11, the coil passes downwardly through a groove or channel l8 formed in the boss H! to the space e immediately above the top face I) of the lower section, where it is caused to assume the looped formation shown in Fig. 6. It emerges from said space through the same aperture through which it entered the same and passes downwardly through the channel l8 in the boss H! to the space I immediately below the lower face a of the bottom section 3 in which space such coil is looped in the manner illustrated in Fig. 7 and just before it emerges from such space, the straight leg g of said coil passes in proximity to a thermostatic well 20, thence passing into the groove or channel in the boss 2| and through the registering groove 2! in the boss 22' directly up to the space d above the top section where it connects with the outlet fitting 23. A bottom pressure plate 24 is applied to the bottom of the section I, such pressure plate being generally similar in configuration to the top pressure plate I1. As shown (Fig. 1) the top and bottom pressure plates I1 and 24 are provided with marginal cored bosses 25 and marginal spacing flanges 26, 26', which latter serve to maintain them in predetermined spaced relation with respect to the face of the particular section to which the same are applied, and consequently render it possible to maintain intimate metal-to-metal contact between the sides of the elliptical or flattened coil and adjacent surfaces of the sections and of the pressure plates respectively, while preventing undue collapse of such coil, all as illustrated in Figs. 3 and 4. Ordinary carriage bolts 2'! are inserted into cored registering openings in the bosses H, II, l2, I2 and 25, which are adapted to receive the same, the heads h of said bolts being enlarged cross-section with respect to the diameter of the cored openings in the aforesaid V bosses; Nuts 28 are threaded on the upper ends of said bolts and said latter nuts serve to also secure front and rear bracket members 29, 29 to said unit, which serve for supporting the unit in any desired location within the cooling chamber of the refrigerator. Preferably skeleton gaskets 6f waterproofed fiber, or of copper and asbestos or of lead, such as illustrated by the reference letter 10, are interposed between the abutting surfaces of the adjacent sections or the abutting surfaces of a section and a pressure plate applied thereto. As illustrated in Fig. 4, the upper section of the unit is preferably of a size sufficient to hold two cube trays. when superimposed on each other and a supporting lid or plate 30 is preferably placed on the lower trays which is inserted in this unit in order to receive and support a second tray. The lower unit, shown in Fig. 4, is intended to receive but a single tray.

In the construction shown in Figs. 8, 9 and 10, the main body of the unit comprises a one-pieced casting 35 having an integral partition 36. Pressure plates 37, all of identical configuration, are applied to the top face of the bottom 38 to the top face of said partition 36 and to the bottom face of the top 39 of said unit, such pressure plates being tightly secured in position by means of cap screws 40 which are threaded into tapped bosses 4| provided on said pressure plates and as shown, the position on the top plate is reversed with respect to that of the two lower pressure plates. In this construction as illustrated, the coils are not shown, it being understood the same are applied and arranged similarly to that of the coil shown in Figs. 3 and 4, except that it will of course be understood that channelled boss 42 will be provided with apertures through the wall thereof, as indicated by the numeral 43 to permit of the emergence of the two legs of the coil into the top of the boss from the space m, the entrance into and emergence of the coil from the spaces 11 and o and also the entrance of the coil into the bottom of the boss 44 and the emergence of the same from the top thereof, such apertures being generally illustrated in Fig. 9.

In the construction shown in Figs. 11, 12 and 13, wherein is illustrated a built-up or sectional unit in which there is provided at the top thereof an ultra-rapid freezing compartment, the reference numeral 50 designates a cast section which is provided with a flat bottom (or top when the same is inverted), and having identical lateral marginal flanges 5| which are provided with bosses 52 and 53 and vanes generally similar to the vanes shown in Figs. 1 to 3, said section being provided with vanes 54 and 55 that are generally similar to the vanes shown in Figs. 1 to 3. Said bosses 53 are provided with a U-shaped channel 56 similar to the bosses shown in Fig. 5. The

bosses 52 are cored or drilled to receive threaded carriage bolts 5'! that serve to maintain the sections in their assembled position. Said sections, as shown, are provided with marginal spacing flanges 58 which are adapted when two sections are inverted and their fiat faces are opposed to each other to form, in co-operation with a pressure plate on the adjacent face of another section upon which it is superimposed, spaces or chambers p for the reception of the cooling coil l5 which is looped at the top in a manner generally similar to that shown in Fig. 5 and at intermediate points is looped in the manner shown in Fig. 14 and at the bottom is looped in the manner similar to that shown in Fig. '7. The channels 56 are cut away, as indicated at 59, to admit of the entrance or emergence, or both, of the cooling coil into such channels, all in the manner generally explained in the construction previously described in connection with the construction in Figs. 1 to '7 inclusive. The top and bottom pressure plates 50 and El are substantially identical and are provided with marginal spacing flanges 62 which correspond to the spacing flanges 58 of the top and bottom sections respectively, thereby admitting of the cooling coil being positioned immediately above the top compartment and again immediately below the lower compartment, and the inner faces of these plates are in sufficiently close proximity to the face of the adjacent section to insure that the spacing will be of the exact width necessary to insure successive metal-to-metal contact between the pressure plates the adjacent flattened coil and the face of the respective section adjacent such coil. In the assembly of these sections into a complete unit, shown in Fig. 11, as well as if desired in the assembly of the sections shown in Figs. 1 to 3, it is desirable that the carriage bolts employed be threaded throughout their length as illustrated at 1 in-Fig. l5 and that the adjacent walls .9 of some of the cooling sections be recessed to conform to one-half of a nut 63 applied to such bolt and thereby as the sections are being assembled, the nuts can be turned down or screwed home upon each section and then the next section is applied and the corresponding nut above the same is also screwed home, thus serving to increase the rigidity of the entire assembly in addition to that which would be effected by merely employing the terminal hex nuts 28 applied to the upper end of the carriage bolts.

A special pressure plate 64 is interposed between the bottom section of the upper compartment shown in Fig. 11 and the top section of the large compartment therein shown and this plate is provided with marginal flanges 58 along the edges of the top and bottom faces thereof, thereby co-operating with the bottom face of the lower section of the top compartment and the top face of the upper section of the large compartment to form spaces 15 for the reception of the cooling coil, which spaces are generally similar in dimensions to the spaces p and of the requisite width to insure metal-tometal contact between the flattened coil inserted therein and the adjacent face of the pressure plate and the section to which it is applied.

In Fig. 17 a still further modification is illustrated which might be termed a duplex cooling unit which is adapted to receive trays positioned side by side. The body of the unit shown may either comprise an open ended casting 10 having a sheet metal cover or top plate H spun thereover, or the top may be cast integral therewith so as to form a one-piece casting. Preferably, as shown, the side walls 12 of the unit at the bottom thereof, a shoulder 13 and av downwardly projecting flange M are provided in order that a pressure plate 15 may be applied directly on said shoulder so that the end of the same will lie within the flange M, thus preventing any likelihood of the entrance of condensed moisture into the space it occupied by the coil. The intake and outlet fittings are carried by the bottom pressure plate and in this construction, as illustrated, it will be understood that although but one fitting is shown, namely the intake fitting is, that the other fitting is positioned directly behind the same and therefore does not appear in this illustration. However, it will be understood that the coil is looped so that one end is connected to the intake fitting I6 and from this the coil travels in a circuitous path generally similar to that shown in Fig. 12 and the outlet leg passes first in proximity to the thermostatic well iii and thence directly to the outlet fitting, not shown.

As is apparent from the foregoing construction wherein I employ sectional walls between which I secure a coil in metal-to-metal contact with the adjacent faces of such walls, it is possible to diecast the cooling unit proper and the cover plate, whereas were the coil embedded in such walls in the manner previously proposed, during the casting operation, the pressure usually required in such die-casting or pressure casting operation would objectionably distort, if not rupture, the embedded coil and likewise were such structure, having 'a coil cast therein, enameled, the temperature at which the enamelling was performed would deleteriously affect or even melt the embedded coil even were it possible to cast such a coil in a ferrous metal wall or a wall of other metal which was suitable for the reception of enamel.

It is particularly desirable to form a cooling unit in the manner herein described wherein the body proper is formed separately from the false side walls, as ready access is thereby afforded to the coils for repair purposes and thereby a defective coil could be readily repaired or renewed without discarding the entire unit as would otherwise be the case were the coil embedded in the side walls in the manner heretofore proposed, see in this connection Reissue Patent No. 18,371.

In lieu of flattening the coil IS in the manner previously described, the same may be previously flattened prior to being applied to the main body of the unit, either by means of a hydraulic press or otherwise, and then the pressure plates are thereafter applied and the cap screws 28 are screwed down so as to intimately engage the flattened coil l5. This latter procedure is particularly desirable in the event the tube is of relatively tough metal, such as copper, since unless the walls of a copper tube are quite thin, it would require considerable pressure to deform the same to the extent indicated in Figs. 3 and l, Whereas on the other hand, if a lead coil is employed, as is usually preferred, it is a comparatively simple matter to deform the same by simply turning down on the cap screws.

My investigations have led to the discovery that where enamelling of the exposed surfaces of the cooling units of automatic refrigerating machines is resorted to, as has been customary in the art for several years past, the efficiency of such units insofar as the ability of the same to refrigerate the food compartment of the refrigerating machine is concerned, can be very substantially increased by employing black enamel or very dark colored enamel which has a high index of heat ray absorption in lieu of white orgray or other merely tinted enamel, such as heretofore employed, which has a much lower index of heat ray ab sorption owing to the high index of reflection of heat rays possessed by white or light colored enamel surfaces. Furthermore, where enamelled surfaces are employed, I have found that both the inner surfaces of the metal pressure plates and the adjacent metal surfaces of the body proper of the cooling unit which are in contact with the cooling coils should be left bare or unenamelled and only the inner and outer surfaces of the unit which are exposed to the circulating current of air within the refrigerator are enamelled. Another advantage of the black enamelled unit as herein described, resides in the fact that it serves to delimit the layer of frost that tends to collect upon the unit during the normal operation of the automatic refrigerating machine within which it is installed. This can be accounted for by the fact that the temperature of the outer surface of the black enamel unit will, owing to its tendency to absorb rather than reflect heat rays from the circulating air in the refrigerator, be at a substantially higher temperature than that of a similar unit having a white enamel or light colored enamel surface and therefore, since in order for frost to accumulate, the outer surface of the frost layer must always be in excess of about 32 F., it will be evident from the foregoing that by accomplishing a greater absorption of heat into the enamelled surface its temperature will be raised and consequently it cannot support as thick a layer of frost as a similar unit having a white enamelled surface especially where the setting of the thermostat control is such as to maintain the food compartment at about 45 F. which is approximately the optimum temperature for such compartments in household refrigerating machines.

It will be understood that while in the various units illustrated in the drawings herein, the entire outer surfaces thereof may be of bare metal, nevertheless, it is preferable that in each unit the entire inner and outer surfaces which are exposed to the air currents of the refrigerator shall be coated with black vitreous enamel of the usual thickness, say 1/200", such as commonly employed for enamelled kitchen ware and the like. Accordingly it will be understood that the units shown in Figs. 1, 8, 11 and 16 have all of the surfaces of the shell or body which are actually exposed to the air currents of the refrigerator in which the same are mounted and also the outer surfaces of all pressure plates employed therein coated with vitreous enamel and preferably black vitreous enamel, but the inner faces of such pressure plates and the opposing faces of the body or shell to which the same are applied are of bare metal and unenamelled.

While I have described the employment of either a dummy pressure plate or a press for the purpose of flattening the coil 15 after the same has been looped in the desired manner, such as illustrated in Figs. 5, 6, 7, 12 and 14, it is to be understood this flattening can also be effected, where lead coils are employed, by applying the enamelled pressure plate and then applying the cap screws 28 to the bolts upon which the sections have been assembled whereupon such screws are screwed home until the flanges on the inner faces of the pressure plate are forced into contact with the corresponding flanges on the walls of the section to which they are applied, thereby effecting the flattening of the coil to an elliptical configuration wherein the two opposing flat sides are in intimate engagement with the adjacent walls of the pressure plate and section to which the coil is applied, and the total length of the portion of the perimeter of the coil which is in metal-to-metal contact with such pressure plate and the adjacent wall of such a section can thus be increased to over one-half the total perimeter of such coil, all as explained in my copending application No. 409,219 filed Nov. 23, 1929, of which this application is a continuation in part.

The term sharp" as employed in the claims, denotes a unit or chamber which is keenly cold or biting cold, in the sense that this term is commonly used with reference to sharp frost or sharp weather.

In the construction shown in Figs. 8, 9 and 10, wherein the pressure plates 31 are applied to the top of the bottom of the unit, to the top of the middle partition and to the bottom face of the top of the unit, there is an increased chilling effect imparted to cube trays positioned on these two lower pressure plates as contrasted with the cooling effect transmitted to cube trays inserted in the compartments shown in Figs. 3 and 4 or in the three lower compartments shown in Fig. 1.1, for the reason that in the construction shown in the latter three figures, the slab or plate on which the cube trays rest, is integral with the side walls or at least with one-half of the side walls of the cooling section or compartment in which the trays are positioned and consequently there is a more substantial interchange of heat between the side walls and their integral fins with said integral slab, than is the case where, as shown in Figs. 8 and 10, the pressure plates are a separate entity from the Walls of the section or unit. As a result, the extremely rapid freezing of ice cubes in cube trays positioned on the plates 31 can be accomplished without the temperature of the food compartment, which is more directly responsive to the actual temperature of the side walls and the integral fins, as well as the top and bottom walls of a unit or section, dropping to as low a temperature as would be the case were the construction shown in Figs. 3, 4 and 11 employed.

In Fig. 1'7, I have illustrated a cooling unit which, as illustrated, is not enamelled, but the same is formed entirely of metal and the tray supporting surface, as well as the surfaces in contact with the coils and all the external surfaces and fins of the unit are of bare metal, although, if desired, the surfaces of this unit, other than those in contact with the coil, may be coated with a vitreous or so-called porcelain enamel. Likewise, it will, of course, be understood that any of the other units may be formed with bare metal surfaces throughout, in lieu of having the exposed surfaces enamelled, as is usually preferred, or if desired, merely the top surface of the transverw tray supporting slabs and the inner surfaces of the chambers containing the coils, may be formed of bare metal and the balance of the surfaces of such unit may be coated with enamel.

While the tubing, when originally bent to form the loops of the desired configuration is preferably circular in cross-section, it may, of course, be flattened to any desired extent before forming the tubing into coils.

A particular advantage of my improved construction is the fact that by virtue of its sectional construction, I have been able to interpose refrigerant coils beneath the tray supporting slabs with which the same is in intimate metal-to-metal contact and at the same time, the side walls of the unit, which are relatively remote from such coils, will be cooled only through the indirect conduction of the heat from such side walls and the vanes carried thereby to the coils, as there is no extended contact between such side walls and the vanes thereon with the coils as such, in fact, in the construction shown, there is no direct contact at all therebetween. As a result, it is possible to obtain remarkably quick freezing of ice cubes or other liquids placed on the tray supporting slabs while at the same time through suitably proportioning the superficial area of the vanes carried thereby to the size of the refrigerator to be cooled, it is possible to maintain the food chamber at the optimum temperature of about 45 F., even though the rate of freezing ice cubes of standard size can be maintained at a high rate not exceeding substantially 14 hours, whereas ordinarily with other units commonly employed, such rapid freezing of ice cubes can only be accomplished by the employment of a cold control device for accelerating the cooling of the unit, with the consequence, that unless such cold control is turned off when the cubes are frozen, the entire ice-box temperature Will be reduced to a deleterious temperature and result in the freezing or excessive chilling of many sensitive substances stored in the food chamber.

When employing a press for flattening the coils in situ, the latter are applied to the desired surfaces of the unit and the pressure plates of the unit may be positioned on top of such coils and then the platen of the press caused to bear thereon until the coils are flattened to the desired extent and then while the pressure is still being applied, the pressure plates and unit sections can be screwed together by screwing down the cap screws on the top of the retaining bolt members, after which the pressure is released and the unit with the parts completely assembled removed from the unit.

The cooling unit illustrated herein lends itself to be made of aluminum, iron or other suitable metal and the separate sections thereof may comprise metal stampings or may be cast in sand molds or produced by a pressure die-casting operation.

By the term intimate contact, as used in the claims, I contemplate metal-to-metal contact as distinguished from the contact which would-result were a layer of enamel to be interposed between the coil and the adjacent surface to which it was applied. Furthermore, by the term line contact, as used in the claims, I contemplate contact in a plane corresponding to a cross-section through the coil and the surfaces of the adjacent walls of the pressure plate or section, as distinguished from the substantial point contact in the same plane of a tube of circular cross-section when a flat surface is brought into intimate contact therewith.

Various modifications within the scope of the appended claims may be made without departing from the spirit of my invention.

Having thus described my invention, what I claim is:

1. An expansion cooling unit for automatic refrigerating machines, comprising a main body having the side, top and bottom thereof integral, a cooling chamber therein, hollow means for maintaining a refrigerant fluid in intimate heatexchange with at least one of the walls of said sharp cooling chamber, vertically extending grooved bosses, integrally formed on said body, positioned at the rear thereof and into which a portion of the aforesaid hollow means extends and, a pressure plate applied to one of the walls of such body and in intimate heat-exchange relation with such hollow means.

2. An expansion cooling unit for refrigerating machines, comprising a main body having a plurality of adjacent sharp cooling chambers therein, such main body being formed of a plurality of substantially similar sections associated together with certain of the adjacent sections being inverted with respect to each other and serving to form a sharp cooling chamber and a plurality of looped metal coils interconnected with each other for refrigerant fluid disposed in two diiferent substantially parallel transverse planes in close proximity to each other and intermediate two adjacent sharp cooling chambers of such unit and a portion of one coil being in direct metal-to-metal contact with the outer wall of one cooling chamber and a portion of the other coil being in direct metal-to-metal contact with the outer wall of an adjacent cooling chamber and said unit having a pressure plate which is interposed between said coils and is in intimate metalto-metal contact therewith.

3. A sectional expansion cooling unit for refrigerating machines, comprising a plurality of superimposed sections of generally similar configuration, the adjacent sections being inverted with respect to each other, certain of the Walls of said sections having vertical apertures adapted to register with each other when such sections are superimposed with respect to each other, bolts in said apertures and certain of said apertures being enlarged at the ends thereof to form a nut-receiving recess and nuts threaded on such bolts and positioned intermediate the ends thereof when such unit is assembled, said nuts lying within the terminal recesses aforesaid and terminal nuts on said bolts for co-operating with such intermediate nuts for holding the assembled sections in their assembled relation.

4. A sectional cooling unit for automatic refrigerating apparatus, having a sharp cooling chamber therein, the bottom of said cooling chamber being formed hollow and in sections, a refrigerant coil interposed between opposing sections of said bottom and having extended direct physical contact with the opposing sections thereof and said sharp cooling chamber having its vertical side walls out of extended direct contact with said refrigerant coils, but being indirectly metallically connected therewith, whereby intense rapid cooling of cube trays positioned in said sharp cooling chamber can be effected without causing the mean temperature of the air in the compartment of a refrigerator in which the unit is mounted to fall below the optimum operating temperature desired therein.

ALEXANDER S. LIIVLPERT.

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