US2784564A - Display case for frozen food - Google Patents

Description

March 12, 1957 J. A. CANTER 2,784,564

DISPLAY CASE FOR FROZEN Foon Filed Feb. 21, 1956 35 I5 i I,

UUU UB 46 32 3 000000 IN V EN TOR.

James A. Canter. BY

His Attorney" United States Patent DISPLAY CASE FOR FROZEN FOOD James A. Canter, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application February 21, 1956, Serial No. 566,863

8 Claims. (Cl. 62--89.6)

This invention relates to refrigerated display cases and particularly to open top cases of the reach-in selfservice type.

In open top display cabinets or cases wherein a sufficient amount of cold air is circulated over a food storage compartment to preserve food products therein at a below freezing temperature and preferably around F. it is necessary to maintain a blanket of air thereover of uniform thickness. This has heretofore been a problem because the formation of eddy currents in the stream of air circulated over the compartment could not be prevented. Such is particularly true when the food load in the compartment is raised to a point closely adjacent the top of an open top compartment so as to render the food packages therein readily accessible without requiring undue stooping or bending on the part of customers. Eddy currents in the stream of air over an open top compartment set up turbulences in the blanket of air and this thins the blanket at certain points above the foods thus causing warm spots in the compartment below the cabinet open top. I have found that the eddy currents are to a great extent formed or set up in a blanket or stream of air circulated over an open top compartment of a reach-in or self-serve display case by air of the blanket or stream escaping entrance into the inlet opening of an air return duct as the air of the stream approaches this opening. The escaping airstrikes a part of the cabinet and rises above the stream of air where, upon comingling with air ambient to the cabinet, it has its direction of flow reversed and swirls around on top of and in contact with the upper part of the air blanket or stream circulating over foods in the open top.

food storage compartment. This swirling air creates a turbulence of air above the blanket or stream thereof and causes, even when none is reaching into the compartment, formation of eddy currents in the blanket or stream of air. In addition to thinning the blanket of air over the top of the compartment the escaping air causes warmer make-up air ambient to the cabinet to enter the stream which augments the formation of eddy currents therein. My invention is specifically directed to minimizing the formation of eddy currents ina blanket or stream of air circulating over an open top food compartment of a display case whereby to maintain a uniform thickness thereof across the compartment and to reduce to a minimum entrance of air from above the open top of the case into the exposed air blanket or stream.

An object of my invention is to retard or prevent as faras possible, escape of cold circulating air in an open top display case from the case in order to maintain stored foods therein at a uniform low temperature and to improve the etficiency of refrigerating apparatus associated with the case.

Another object of my invention is to provide means in or on an open top refrigerated display case which will reduce or substantially eliminate swirling and co- "mingling of air escaping entrance into. the inlet of a return air duct or flue in the case above an air stream circulating .over a food storage compartment therein.

A further object of my invention is to momentarily trap a substantial amount of air which escapes from a cold stream thereof circulated over the top of a food compartment upon approaching the inlet of an air return flue in an open top display case and to continually release some of the trapped air to the air stream for entrance into the return flue.

A still further and more specific object of my invention is to provide an open bottomed pocket or turbulence chamber in front of and above the inlet to a return air flue for a stream of air in an open top refrigerated display case wherein air escaping the return flue inlet will be momentarily trapped against outward flow from the case, is permitted to swirl in the turbulence chamber and will eventually reenter the stream and flow therewith into the flue.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings:

Figure 1 is a perspective view of a horizontally elongated refrigerated display case having my invention embodied therein;

Figure 2 is a vertical sectional view taken on the line 22 of Figure 1 through the open top display case cabinet showing the essential features of the invention; and

Figure 3 is a fragmentary sectional view similar to Figure 2 showing how air swirls at the top of a conventional display case devoid of the improvement herein disclosed.

In the drawing 10 generally designates an open top display case or cabinet having insulated end walls 20 (see Figure 1), an insulated bottom wall 11 (see Figure 2), an insulated upright front wall 12 including a multiple pane glass upper part or section 13, an insulated upright back wall 14 and an insulated hood 15 extending forwardly over back wall 14 a short distance. Suitable metal plates or sheets are secured together and spaced by brackets or the like from the liner of walls 11, 12, 13 and 14 (see Figure 2) to form an impervious bottom wall 16, an upright front wall 17 and. a rear wall 18 of an open top frozen food storage compartment 19 within the cabinet 1%). The walls 16, 17 and 18 also provide an air passage 21 below compartment 19, and an upright front air feeder flue 22 and an upright back return air fine 23 respectively within cabinet 10. A single glass plate 24, spaced from the multiple pane glass section 13, forms the upper portion of the front wall of compartment 19 and the top wall part of flue 22. An upstanding continuation of wall 18 is formed to provide a shroud 26 in the hood 15 for a purpose to be presently described. An insulated horizontally anchored partition 25 is spaced from and cooperates with the depending end of the insulated forward portion of hood 15 to provide an inlet 27 for the return air fine 23. The vertically spaced apart means, partition 25 and the end of the depending insulated forward portion of hood 15, extends through the length of the cabinet. Splitter means in the form of a lip 31, extending inwardly of the case from the front glass section 13, and spaced preferably transparent bafiles 32 oifset slightly relative to one another secured beneath lip 31 split or divide ,a stream of air egressing from the upper outlet end of feeder flue 22 into a plurality of layers for and in the manner to be hereinafter explained. I mount an evaporator 33 of a refrigerating system within the space 34 of hood 15 be low the shroud 26 and a motor 36 and fan 37 above the space 34. The shroud 26 surrounds fan 37 and creates a: suction therein to pull air upwardly through space 34 over and around evaporator 33. Evaporator 33 is connected by a conduit 41 to a sealed motor-compressor enclosing casing 42 of a refrigerant translating unit which also includes a condenser 43. Condenser 43 receives compressed refrigerant from the compressor in casing 42 wherein it is cooled and liquified. Liquid refrigerant is directed to evaporator 33 through a conduit 44 and its entrance into the evaporator may be controlled by an expansion valve or the like (not shown). Operation of the motor and compressor of the refrigerating system may be under the control of a thermostatically actuated switch as is conventional in the art.

According to my invention I provide an open bottomed pocket or turbulence chamber in front of theinlet openingof the return air flue. atthe backof the present display casefor a purpose to become apparent hereinafter. A member preferably of molded plastic translucent material including . Wall partitions 45, 46 and 47 extends along the length .of thezinlet 27 of the back return air flue23 in cabinetlfi'in front and above this in let. Wall portion 47 of the translucent member is removably locked to the front parto'f hood 15 by spring clips or thelike withthe end of wall portion dfibearing'against the hood. Wall portions 46 and 47 of the molded plastic-member close'the lowerzportion of a lamp compartmentdsat the front of hood 15 in which is suitably mounted an illuminating lamp bulb 49. Wall portions45 and 46 of the translucent member cooperate with one another and with the front of hood 15 to form or provide an open bottomed air turbulence chamber or pocket '50. Suction in the shroud '26 and chamber 34, created .by operation of motor 36 and fan 37, draws air into the inlet openmg 27 upwardly through and over the evaporator 33, Which cools the air to a temperature well below 32 F., and forces the air downwardly in the back return flue 23. The cool air is circulated forwardly from flue 23 across the passage 21 and upwardly in the feeder flue 22 to cool thewal ls '16, 17 and 18 and consequently packaged food, such as ice cream, contained in compartment 19. The alr stream egressing from the outlet of feeder flue Z2 is at a temperature of approximately -l F. and is stratified or divided into a plurality of superimposed streams or layers and directed at different velocities with respect to one another horizontally rearward over the open top of compartment 19 by the splitters or bafiles 32 The arrangement of splitters 32 is such that they will deflect a fast moving layer of air, a slower moving layer of air thereabove and a still slower moving layer of air from the bottom to top respectively of the blanket or stream of air flowing over the open top of compartment 19. As air in the blanket or plural layer stream approaches or nears the inlet opening 27 of back return flue 23 some of the air in the slower moving upper layer or strata of the stream becomes slightly warmed due to its exposure to air above the open top of compartment 19 and due to an additional amount of air induced into motion by the stream above that which is circulated by the fan'or fans. This warmer air, relative to the temperature of the lower layers or strata thereof, has a tendency to rise and escape entrance into the inlet 27. This is an inherent characteristic in open top display cases oc curring regardless of the relative height of inlet and outlet openings of air flues therein. In such cases where the air is circulated over a compartment toward the forward side thereof the top of the case front wall must be disposed a considerable distance above a forward flue inlet and the top of the food load or air escaping entrance to the flue inlet will flow over its front wall and all the escaping air will be lost to air ambient to the case. Thus if a front wall of a display case is elevated above the food load sufficiently to stop air tending to escape a' front flue inlet the feature of locating the top of the food load closelyadjacent the open top of a display case will be defeated. Substantially all or the. greater portion of the rising or escaping air is, in the present disclosure, caught;

and trapped in the open bottomed turbulence chamber or pocket 50 and swirls therein. The swirling air looses its kinetic energy in chamber 50 and as more escaping air is caught in this chamber some of the trapped air swirling therein reenters the stream of rearwardly circulating air and flows therewith into the inlet. This process continues and in doing so the warmed air escaping entrance into the inlet 27 is prevented from flowing forwardly of hood 15, comingling with air above the blanket or stream circulating across the open top of compartment 19 and creating a swirling action of air along the length of the exposed air stream. In other words swirling of air'escapingentrance into theinlet 27 of the return air fiue 23 is-confined, by the turbulence chamber 50, in a region where it will do little harm and is prevented from spreading forwardly over the major portion of the blanket or stream of air above the open top compartment 19. In this manner the formation or establishment of eddy current in the circulatingblanket or stream of air over the food compartment is substantially eliminated so as'not to retard movement of the blanket or stream. This results in the maintenance of a more uniform thickness of the blanket or stream of aircircu- 'lating over compartment 19. By trapping air escaping entrance into inlet 27 and eliminating theformation of .a wide spread turbulence or swirling of air above the circulating exposed stream thereof less makeup air enters cabinet or case 10 and a lower temperature of foods adjacent the open top of display case or cabinet is obtained.

In order to emphasize comparison of the present improvement with or over conventional open top display cases or cabinets I show in Figure 3 of the drawings a display case of a construction similar to that disclosed in Figures 1 and 2 devoid of my improvement and illustrating the extended zone of harmful swirling action of air above the blanket or stream of cold air being circulated over the open top food compartment. The arrows 51 indicate the extended swirling or turbulence of air which escapes entrance into the inlet 27 of the return air flue. It should be noted that the turbulence of air above the exposed air stream extends substantially to the front of the open top compartment 19. The retardation inmovement of the blanket or stream of air by eddy currents established therein by the swirling air is indicated in Figure 3 by the dotted lines 52. This comparison is realistic and actual tests have shown that, with the addition of my improvement to a conventional open top display case, a lower temperature of packaged ice cream in the upper portion of compartment of from 10 to 15 F. is had by my invention over that obtained in a conventional case under the same operating and ambient conditions.

Since packaged foods stored in the upper portion of compartment 19 aremore diflicult to cool to a low uniform temperature than packaged foods elsewhere in compartment 19, my invention is particularly beneficial to this characteristic of open top display cases.

From the foregoing it should be apparent that my improvement permits the flow of a fast unretarded, uniform thickness of a blanket or stream of cold air over food stored in an open top compartment of a substantially open top display case to thereby more efiiciently and uniformly refrigerate foods stored therein to a below freezing temperature. The front wall portion of the molded plastic translucent member, forming the turbulence chamber in the present disclosure, may serve as a display or advertising space to inform customers of the various kinds or flavors of ice cream stored in the cabinet. For example, this wall portion of the plastic member may have indicia printed or painted on the front thereof and made readily visible at the forward side of the case by being illuminated by the lamp in the lamp compartment above the turbulence chamber. Thus the molded plastic member serves a two-fold-purpose for an open top display case.

:While the form of embodiment of the invention as-herein disclosed constitutes a preferred form, it is to be understood that other forms might be adapted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerated display case, an elongated substantially open top cabinet provided with a compartment having an air passage therebelow, a return air flue at one side thereof with its inlet near the top of said com partment and a feeder flue at the side of said compartment opposite said return flue with its outlet also near the top of the compartment, means for circulating air downwardly in said return flue through the inlet thereof, across said passage, upwardly in said feeder flue and out of the outlet thereof in a stream over the top of said compartment in exposed relationship to air at the open top of said cabinet, and means for cooling the circulating air, the improvement which comprises the provision of a turbulence chamber along the length of said compartment in front of and above the inlet of said return flue, said chamber being open at its bottom to receive and momentarily trap air which escapes from said stream thereof upon approaching the inlet of said return flue whereby said trapped air swirls in said chamber, and the swirling trapped air causing 'some of it to reenter air in said stream adjacent said inlet of the return flue and flow therewith into said return flue to minimize entrance of air from above the open top of said cabinet into said air stream.

2. In a refrigerated display case, an elongated substantially open top cabinet provided with a compartment having an air passage therebelow, a return air flue at the back thereof with its inlet adjacent the top of said compartment and a feeder flue at the front of said compartment with its outlet also adjacent the top of the com partment in substantially the same horizontal plane with the inlet of said return flue, means for circulating air downwardly in said back return flue through the inlet thereof, forwardly across the case through said passage, upwardly in said front feeder flue and out of the outlet thereof in a stream toward the rear of the case over the top of said compartment in exposed relationship to air .at the open top of said cabinet, and means for cooling the circulating air, the improvement which comprises locating an open bottomed pocket along the length of said compartment in front of and above the inlet of said back return flue, said pocket serving to receive and momentarily trap air which escapes from said stream thereof upon approaching the inlet of said return flue for decreasing flow of the escaping air into the region above the stream of air circulating over said compartment whereby to minimize the formation of eddy currents in said stream of air.

3. In a refrigerated display case, an elongated substantially open top cabinet provided with a compartment having an air passage therebelow, a return air flue at the back thereof with its inlet adjacent the top of said compartment and a feeder flue at the front of said compartment with its outlet also adjacent the top of the compartment in substantially the same horizontal plane with the inlet of said return flue, means for circulating air downwardly in said back return flue through the inlet thereof, forwardly across the case through said passage, upwardly in said front feeder flue and out of the outlet thereof in a stream toward the rear of the case over the top of said compartment in exposed relationship to air at the open top of said cabinet, and means for cooling the circulating air, the improvement which comprises the provision of a turbulence chamber along the length of said compartment in front of and above the inlet of said back return flue, said chamber being open at its bottom to receive and momentarily trap air which escapes from said stream thereof upon approaching the inlet of said return flue whereby said trapped air swirls in said chamber, and the swirling trapped air causing some of it to reenter air in said stream adjacent said inlet of the returnflu'e and flow therewith into said return flue to minimize entrance of air from above the open top of said cabinet into said air stream.

4. In a refrigerated display case, an elongated substantially open top cabinet provided with a compartment having an impervious bottom forming the top of an air passage therebelow, a return air flue at one side thereof with its inlet near the top of said compartment and a feeder flue at the side of said compartment opposite said return flue with its outlet also near the top of the compartment, means for circulating air downwardly in said return flue through the inlet thereof, across said passage, upwardly in said feeder flue and out of the outlet thereof in a stream over thetop-of said compartment in exposed relationship to air at the open top of said cabinet, means for cooling the circulating air, and splitter means at the outlet of said feeder flue for stratifying air egressing therefrom into a plurality of layers of different velocity with a faster moving layer underlying a slower moving layer and for directing said stratified stream of air toward the inlet of said return flue, the improvement which comprises locating an open bottomed pocket along the length of said compartment forwardly of and above the inlet of said return flue, said pocket serving to receive and momentarily trap air which escapes from an upper slower layer thereof in said stratified stream upon approaching the inlet of said return flue for decreasing flow of the escaping air into the region above the stratified stream of air circulating over said compartment whereby to minimize formation of eddy currents in said stream of air.

5. In a refrigerated display case, an elongated substantially open top cabinet provided. with a compartment having an impervious bottom forming the top of an air passage therebelow, a return air flue at one side thereof, with its inlet near the top of said compartment and a feeder flue at the side of said compartment opposite said return flue with its outlet also near the top of the compartment, means for circulating air downwardly in said return flue through the inlet thereof, across said passage, upwardly in said feeder flue and out of the outlet thereof in a stream over the top of said compartment in exposed relationship to air at the open top of said cabinet, means for cooling the circulating air, and splitter means at the outlet of said feeder flue for stratifying air egressing therefrom into a plurality of layers of different velocity with a faster moving layer underlying a slower moving layer and for directing said stratified stream of air toward the inlet of said return flue, the improvement which comprises the provision of a turbulence chamber along the length of said compartment forwardly of and above the inlet of said return flue, said chamber being open at its bottom to receive and momentarily trap air which escapes from an upper slower layer thereof in said stratified stream upon approaching the inlet of said return flue for decreasing flow of the escaping air into the region above the stratified stream of air circulating over said compartment whereby to minimize entrance of air from above the open top of said cabinet into said air stream.

6. In a refrigerated display case, a substantially open top cabinet provided with a compartment having an impervious bottom forming the top of an air passage therebelow, a return air-flue at the back thereof with its inlet adjacent the top of said compartment and a feeder flue at the front of said compartment with its outlet also adjacent the top of the compartment in substantially the same horizontal plane with the inlet of said return flue, means for circulating air downwardly in said back return flue through the inlet thereof, forwardly across the case through said passage, upwardly in said front feeder flue and out of the outlet thereof in a stream over the top of said compartment in exposed relationship to air at the open top of said cabinet, means for cooling the circulating air, and splitter means at the outlet of said feeder flue for stratifying air egressing therefrom into aplurality oflayers of differentvelocity with a faster moving l'ayer underlyinga slower moving layer and for directing said Stratified stream of air rearwardly of the case toward the inlet of said return flue, the improvement which comprises locating an open bottomed pocket along tthe length :of said compartment in front of and above the inletof'said back return flue, said pocket serving to receive and momentarily trap. air which escapes from an upper slower layer thereof in said stratifi'ed stream upon approaching the inlet of said return flue for decreasingflow of'the escaping-air into the region above the stratified stream of air circulating over said compartment whereby to minimize formation of eddy vcurrents in said stream of air.

7. In a refrigerated display case, a substantially open top cabinet provided with a compartment having an impervious bottom forming the top. of an air passage therebelow, a'return air flue at the back thereof with its inlet adjacent the topof said cornpartment and a feeder flue at the front of said compartment with its outlet also adjacent the top of the compartment insubstantially the same horizontal plane with the inlet of said return flue, meanstfor circulating air downwardly in said back return flue through the inlet'thereof, forwardly across the case through said passage, upwardly insaid front feeder fiue and .out of the outlet thereof inna stream over the top of saidcompartment in exposed relationship to air at the open top of said cabinet, means for cooling the circulating air, and splitter means atithe outlet of said feeder flue'for stratifying air egressing therefrom into a plurality of layers of different velocity with a faster moving layer underlying a slower moving; layer and for directing said Stratified stream of air rearwardly of the case toward the inlet vof said return flue, the improvement which comprises the prov-ision of a turbulence chamber along the length of said compartment forwardly of and above the inlet of said back return flue, said chamber being open at it-szbottom to receive and momentarily trap air which escapes f'roman upper slower layer thereof in said'ast rati fied stream upon approaching the inlet of said back return flue whereby said trappedair swirls in said'chamber, and the swirling trapped airica'using some-of it to reenter air in said stream adjacent said inlet of the return flue and flow'therewilthinto said back returnfiue to minimize entrance of :air from above the open top of said cabinet into said stratified' air stream.

8. In. a refrigerated display case, a substantially open top cabinet having, a frozen food storage compartment therein provided with a passage therebelow, a return air flue at one side thereof and a feeder flue at the side of said compartment opposite said return flue with its outlet near the-top-of the compartment, vertically spaced apart means near the top of said compartment providing said return flue with an inlet, means for circulating air downwardly in said return flue through the inlet thereof, across said passage, upwardly in said feeder 'flue and out of the outlet thereof in a stream over the top of said compartment in exposed relationship toair at the open top of said cabinet, and means for cooling, the circulating air to a temperature well below 32 F-., the improvement which comprises the provision of a turbulence chamber along the length of said compartment in front of said vertically spaced apart means above the inlet of said return flue, said chamber being open at its bottom to receive and momentarily trap air which escapes from said stream thereof upon approaching the inlet of said return flue whereby said trapped air swirls in said chamber, and the swirling trapped air causing some of it to reenter air in said stream adjacent said-vertically spaced apart means and flow therewith into the inlet of said return flue to minimize entrance of air from above the open top of said cabinet into said air stream.

References Cited in the file of this patent UNITED STATES PATENTS 2,715,321: Burger Aug 16, 1955

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