US3149476A

US3149476A - Refrigerated display cabinet

Info

Publication number: US3149476A
Application number: US198962A
Authority: US
Inventors: Beckwith Sterling
Original assignee: Dual Jet Refrigeration Co
Current assignee: Dual Jet Refrigeration Co
Priority date: 1962-05-31
Filing date: 1962-05-31
Publication date: 1964-09-22
Anticipated expiration: 1981-09-22
Also published as: GB965881A; DK117780B; DE1451072A1; CH405375A

Description

P 1954 s. BECKWITH 3,149,476

' REFRIGERATED DISPLAY CABINET Filed May 31, 1962 FIG-Z Z INVENTOR, Shading Beckwzih.

BY Q9/1444) A X M United States Patent M 3,149,476 REFRIGERATEE) DZSPLAY CABHNET Sterling Beclrwith, Libertyviiie Township, Lake County,

Iii, assignor, by mesne assignments, to Dual .let Refrigeration Company, a corporation of Hlinois Filed May 31, 1962, Ser. No. 198,952 7 Claims. (-fCl. 62-256) This invention relates to improvements in a refrigerated cabinet or enclosure of the type having an open side permitting access to an enclosed refrigerated space. The invention particularly relates to devices of the type which are capable of maintaining a refrigerated state within the enclosed space while still providing an opening for access to the contents.

In an application of Hagen et al., Serial No. 54,077, filed September 6, 1960, and in the issued Simons Patent No. 2,862,369, there are described refrigerated display cabinets which are provided with access openings exposed to the atmosphere while still being capable of maintaining the contents in a refrigerated state. Loss of refrigeration from the enclosed space through the access opening is reduced in a highly effective manner in these construetions by the use of an air curtain which is continuously advanced across the open side from one edge of the opening to the opposite edge. The air curtain in these constructions is adapted to be formed of adjacent panels of air, with the innermost panel comprising a refrigerated cold air panel, and with one or more outer panels having temperatures approaching the ambient temperature. It has been found that it is desirable to recirculate at least the inner cold air panel, and, at times, the adjacent guard panels, to conserve the refrigeration and to maintain the enclosed space in a satisfactory refrigerated state.

In these constructions there are described assemblies which include nozzles extending across the bottom edge of the access opening to direct the air panels upwardly across the opening towards inlets which extend across the top side of the access opening. As an alternative, the nozzles are located across the upper edge for projecting the air panels downwardly toward inlets arranged across the bottom edge. It is also contemplated that the air nozzles be located across one of the lateral edges of the opening for directing the corresponding air panels across the opening toward inlets in the opposite edge. Because of the more desirable effect of gravity on the higher density cold air, it has been found preferable to provide the air curtain with a downward movement from nozzles across the top to inlets across the bottom. The following description will refer to this preferred construction, although it will be understood that the concepts to be described are also applicable to other directions of flow.

It has been applicants experience that there is a tendency for frost formation in the area of the outlet nozzles, particularly in the passage or passages confining the innermost refrigerated streams. This situation has led to disruption in the normal flow of the air panels thereby increasing the difficulties in obtaining uniformity in the temperature control. Furthermore, the tendency for accumulation of frost in these nozzles necessitates an increase in the frequency of defrosting operations and, therefore, the over-all efficiency of the cabinet operation is reduced.

In applicants copending applications Serial No. 88,879, filed February 13, 1961, now Pat. No. 3,082,612, and Serial No. 106,805, filed May 1, 1961, now Pat. No. 3,094,851, reference is made to the use of honeycomb sections for the nozzles used to direct the air panels across the access opening. These honeycomb sections are characterized by a plurality of small openings and, when employed in lengths from about 1 to about 6 inches, they 3,149,476 Patented Sept. 22., 1964 are particularly effective in providing uniformity in the laminar air panels.

The problem of frost accumulation noted above is particularly troublesome, however, when such honeycomb nozzles are employed. The small openings in the honeycomb sections can become substantially reduced in crosssection if frost accumulates, and this disrupts the uniformity of the operation. In addition, the larger surface area presented by these sections accelerates frost accumulation and necessitates more-frequent defrosting operations.

It is an object of this invention to provide improvements in refrigerated cabinets which are particularly directed to decreasing frost formation and accumulation in the outlet areas for air panels employed in the cabinets.

It is a more particular object of this invention to provide a heating means adapted to be located adjacent nozzle outlets for refrigerated cabinets, the heating means being effective to inhibit frost formation in these areas thereby increasing the efiiciency of the cabinet.

These and other objects of this invention will appear hereinafter, and for purposes of illustration, but not of limitation, specific embodiments of this invention are shown in the accompanying drawings in which FIGURE 1 is a schematic elevation, partly cut away, of a refrigerated enclosure characterized by the features of this invention;

FIGURE 2 is a fragmentary view in section of the nozzle area of a refrigerated cabinet having associated heating means; and

FIGURE 3 is a detail plan view of the heating means employed in the nozzle area.

As indicated, the improvements of this invention are directed to refrigerated enclosures of the type which define an access opening in one wall which is provided for communication with the otherwise enclosed space. The enclosures are provided with a plurality of nozzles arranged in side-by-side relationship across one edge of an access opening and corresponding inlets are located across an opposite edge of the access opening. The inner nozzles and inlets are provided for the passage of refrigerated air streams across the access opening, while the outer nozzles and inlets circulate progressively warmer air panels. As indicated, the refrigerated streams are circulated through passages having refrigeration coils or the like situated therein, and one or more of the outer streams may also be refrigerated.

The problem of undue frost formation and accumulation is particularly apparent in the innermost refrigerated stream or streams, and the accumulation appears to occur with greater regularity in the area of the outlet nozzles for these refrigerated streams. It has been found that the provision of heating means in me path of the refrigerated streams adjacent the nozzle areas serves to effectively reduce the frost formation and accumulation. The refrigerated streams contact these heating means prior to contact with the outlet nozzles. The heating means, which are of relatively low capacity, serve to raise the temperature of the stream a small amount in the nozzle area, and this inhibits the frost formation. Thus, if the innermost stream flowing through the cabinet is at -20 F., the heating means located adjacent the nozzle for this stream may be adapted to raise the temperature to 15 F. Thisincrease in temperature is not particularly critical, since a difference of even one or two degrees has been found effective to some extent. However, if the temperature is raised a relatively large amount, then the burden on the refrigerating coils must be unduly increased and, therefore, the temperature differential has this practical limitation.

In the preferred form of this invention, the heating means comprises a framemember which extends across I of turns around the frame.

conventional type, however, a thin wire is preferably employed, and the turns are preferably uniformly spaced apart asubstantial amount when compared with the thickpanel. As indicated, the concepts of this invention are particularly applicable where honeycomb sections are usedas the nozzle means. The heating means described, when employed in combination with these sections, generate heat to a degree sufiicient to raise the temperature of the innermost refrigerated panel or panels thereby inhibiting frost formation on the exposed surfaces of the honeycomb sections.

The accompanying drawings illustrate a refrigerated cabinet 19 which is provided with the improvements which form the subject matter of this invention. The enclosure comprises a top wall 12, bottom wall 14, back wall'lfi, front wall 18 and side walls 20. The front wall 18 defines an opening 22 for access to the refrigerated space'24. An internal wall 26 defines the extent of the refrigerated space.

Partitions 23 and 30 and the inner and outer walls define

passages

32, 34 and 36. These passages confine streams 38, 4t) and 42 which then form laminar air panels as they cross the access opening.

Located in the passages in the bottom area of the cabinet there are provided refrigeration coils 33 and circulating means 35 as disclosed in the'prior applications.

At least the innermost panel 38 is to be refrigerated, al-' though refrigeration means can be provided for the other panels. The concepts of this invention contemplate the use of two or more panels, and the invention is not necessarily limited to the three panels shown. Circulating means are provided for the innermost panel, and preferably are provided for all of the panels, although in some instances the outermost panel can be efliciently circulated without specific mechanical aid.

Screens 44 are provided in the path of the outer panels 40 and 42 to prevent entry of insects and other foreign material into the air passages. A similar screen may be provided over the passage 32. However, a heating element 46, of the type described in the copending application Serial No. 198,963, dated May 31, 1962, and entitled Refrigerated Enclosure, can be advantageously substituted for the screening means.

Outlet nozzles 48 for the air streams are located at the top edge of the access opening. As noted, there is a tendency for frost to collect in these areas, particularly in the innermost refrigerated passage 32. It has been discovered that the accumulation of frost can be effectively reduced if a heating means 50 is located in the air passage adjacent the nozzle 48. This heating means is positioned to contact the stream 32 priorto passage of the stream through the nozzle. Although the heating means 50 is shown only in the passage 32, it will be appreciated that the concepts of this invention are applicable to all of the nozzle areas where undue frost'accurnulation presents problems. s V a The heating means 54 shown comprises a rectangular frame. member 52 which may be suspended across the air. passage and:secured to the side walls of the cabinet 'bymeans o f'b'racket members 54.. To provide rigidity in the frame, braces 56 are employed.

a An electrical resister wire 58 is formed in a plurality The wire may be of any mass of the-wire. This arrangement permits uniform dis- V tribution of heat without unduly interrupting the flow of the air panels. J Thin plastic coated wire wound around a steel frame with about one inch between turns has been found to be a suitable construction, although many vari- The use of theheating 59in thejnozzle area is ations in this respect will be obvious to those skilled in the art.

particularly effective where honeycomb sections of the type illustrated comprise the nozzles 48. The combination of the small passages in these sections as well as the large surface area presented accentuates the frost problem. It has been found that the use of heating means of the type described provides noticeable increases in the effectiveness and efficiency of operation of the refrigerated cabinets.

One of the problems encountered has been the frosting effect resulting from the variations in temperature of the air stream due to the operation of expansion valves in the system. When the temperature of the cold air stream is on the increase, the contacted surfaces of the honeycomb, etc., will be from 13 F. colder than the air stream. This ordinarily will accelerate frost formation on the colder surfaces. The presence of the heating means of this invention in close proximity of the cold surfaces operates to minimize the effect of the temperature changes whereby frost formation is eliminated.

It will be understood that various modifications may be made in the above described refrigerated cabinet which provide the characteristics of this invention without departing from the spirit thereof, particularly as defined in the following claims.

I claim:

1. in a refrigerated cabinet defining an a'ccess opening in one wall communicating the otherwise enclosed space with the outside atmosphere, outlets across one side of said access opening and inlets across the other side of the access opening, means for circulating a plurality of air panels from the outlets to the inlets across said opening and through separate passages about said enclosure, and means for refrigerating at least the innermost one of said panels, the improvement comprising heating means disposed in the passages confining said innermost panel, said outlet comprising honeycomb sections extending across each of said passages immediately in advance of the inlet of said heating means being located immediately in ad- Vance of the inlet end of the outlet for said panel at one edge of said access opening, and said heating means being adapted to generate heat to raise the temperature of said innermost panel thereby inhibiting frost formation.

2. In a refrigerated cabinet of the type which defines an access opening in one wall communicating another- Wise enclosed space with the ambient atmosphere, and

which is provided with at least one inner cold air inlet and at least one outer warmer air inlet, at least one inner cold provement comprising heating means in the passage con-' fining the said innermost refrigerated panel, said nozzles comprising honeycombsections extend ng across each of said passages, saidheating means being disposed immediately in advance of the inlet'end of the nozzles for said' passages,.and said heating means being adaptedto' generate heat to raise the temperature of said' innermost panels thereby inhibiting frost formation.

3. In a refrigerated cabinet defining an accessopening in one wall communicating the otherwise enclosed space with the outside atmosphere, means for circulating a plurality of air panels acrossjsaid opening and through said enclosure, and means for refrigerating at least the inner-,

most one of said panels, the improvement comprising a honeycomb section extending across each'of said passagesforming outlet nozzlesfor said panels at one edge of 'saidaccess opening, a heating means disposed immediately in advanceof the inlet end of the honeycomb sectionin the passage confining said innermost panel, said heating'means' being adapted to generate heat to raise the temperature of said innermost panel thereby inhibiting frost formation.

4. In a refrigerated cabinet of the type which defines an access opening in one wall communicating an otherwise enclosed space with the ambient atmosphere, and which is provided with at least one inner cold air inlet and at least one outer warmer air inlet, at least one inner cold air nozzle and at least one outer warmer air nozzle, said inlets and nozzles extending in side-by-side relationship across opposite edges of said access opening, passages communicating each of the corresponding inlets and nozzles, circulating means in at least some of the passages for forcing air through the passages in the form of panels across said access opening, and refrigeration means disposed in at least some of said passages and adapted to refrigerate at least the innermost of said panels, the improvement comprising heating means in the passage confining the said innermost refrigerated panel, said heating means comprising a frame member suspended in and extending across said passage adjacent said nozzle, and an electrical resister wire wrapped around said frame member along the length thereof, said heating means being disposed adjacent the nozzie for said passage, and said heating means being adapted to generate heat to raise the temperature of said innermost panel thereby inhibiting frost formation.

5. A refiigerated cabinet in accordance with claim 4 wherein the turns of said wire are spaced apart a distance substantially greater than their widths to permit essentially undisturbed movement of said innermost panels through said passages.

6. In a refrigerated cabinet defining an access opening in one wall communicating the otherwise enclosed space with the outside atmosphere, means for circulating a pinrality of air panels across said opening and through said enclosure, and means for refrigerating at least the innermost one of said panels, the improvement comprising heating means disposed in the passages confining said innermost panel, said heating means comprising a frame member suspended in and extending across said passage, and a plurality of spaced apart turns of an electrical resister Wire wrapped around said frame member along the length thereof, said heating means being located adjacent the outlets for said panel at one edge of said access opening, and said heating means being adapted to generate heat to raise the temperature of said innermost panel thereby inhibiting frost formation.

7. In a refiigerated cabinet defining an access opening in one wall communicating the otherwise enclosed space with the outside atmosphere, means for circulating a plurality of air panels across said opening and through said enclosure, and means for refrigerating at least the innermost one of said panels, the improvement comprising a honeycomb section extending across each of said passages forming outlet nozzles for said panels at one edge of said tccess opening, a heating means disposed above the honey- :omb section in the passage confining said innermost panel, said heating means comprising a frame member suspended in and extending across said passages, and a plurality of spaced apart turns of an electrical resister wire wrapped around said frarne member along the length thereof, and said heating means being adapted to generate heat to raise the temperature of said innermost panel thereby inhibiting frost formation.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,149,476 D t d September 22, 1964 Invent Sterling Beckwith It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, lines 37 and 38 (claim 1):

After "passages" delete "immediately in advance of the inlet of".

Signed and Sealed this Fifteen D of August 1978 [SEAL] Attest:

DONALD W. BANNER RUTH C. MASON Arresting Officer Commissioner of Patents and Trademarks

Claims

1. IN A REFRIGERATED CABINET DEFINING AN ACCESS OPENING IN ONE WALL COMMUNICATING THE OTHERWISE ENCLOSED SPACE WITH THE OUTSIDE ATMOSPHERE, OUTLETS ACROSS ONE SIDE OF SAID ACCESS OPENING AND INLETS ACROSS THE OTHER SIDE OF THE ACCESS OPENING, MEANS FOR CIRCULATING A PLURALITY OF AIR PANELS FROM THE OUTLETS TO THE INLETS ACROSS SAID OPENING AND THROUGH SEPARATE PASSAGES ABOUT SAID ENCLOSURE, AND MEANS FOR REFRIGERATING AT LEAST THE INNERMOST ONE OF SAID PANELS, THE IMPROVEMENT COMPRISING HEATING MEANS DISPOSED IN THE PASSAGES CONFINING SAID INNERMOST PANEL, SAID OUTLET COMPRISING HONEYCOMB SECTIONS EXTENDING ACROSS EACH OF SAID PASSAGES IMMEDIATELY IN ADVANCE OF THE INLET OF SAID HEATING MEANS BEING LOCATED IMMEDIATELY IN ADVANCE OF THE INLET END OF THE OUTLET FOR SAID PANEL AT ONE EDGE OF SAID ACCESS OPENING, AND SAID HEATING MEANS BEING ADAPTED TO GENERATE HEAT TO RAISE THE TEMPERATURE OF SAID INNERMOST PANEL THEREBY INHIBITING FORST FORMATION.