US 2447759 A
Description (OCR text may contain errors)
2 Sheets-Sheet 2 Aug. 24, 1948. M. D. MacMAsTER v OPEN TOP ACCESS REFRIGERATED DISPLAY CASE Filed oct. 2o, 1941 @www Fl g4.
INVENTOR. MALCOLM D. Mac/44145715? BY ZZ Z-WTV ATTORNEY Figi.
Patented Aug. 24, 1948 OPEN TOP ACCESS REFBIGEBATED DISPLAY CASE Malcolm D. MacMaster, Yardley, Pa., asllgnor to y C. V. Hill d: Company, Inc.. a corporation oi' New Jersey Application October 20, 1941, Serial No. 415,684
My invention relates to open type refrigerated display cases adapted for the preservation and display of meats, dairy products and the like.
Open type display cases are of great advantage i in self service stores and elsewhere but they have not generally been used heretofore for the display and preservation of meats and dairy products because of the necessity of refrigerating such products.
Numerous types of refrigerated vegetable stands which are open at the top have been developed heretofore. as exemplified by the patent of J.` S.
,Hill, No. 2,207,586, dated July 9, 1940. However.
open type vegetable stands are designed to cause moisture to be deposited upon the vegetables, whereas the deposition of moisture on meats and dairy products is objectionable even when such products are wrapped. Furthermore, vegetable stands are generally constructed so that a portion of the cold air from within the display space will spill over the front or side walls of the case to permit moist warm air to flow into contact with the vegetables and deposit moisture thereon. While this is desirable in a vegetable stand the continual loss of cold air materially reduces the refrigerating efficiency of the construction.
Certain other constructions. such as those used for the display of salads and the like in cafeterias,
s claim. (ci. liz-sas) tion of the display space. In this way the air within the display space is continuously circulating without drawing in substantial quantities of warm moist air which might deposit moisture on the articles being displayed. Moreover, the cooled air is skimmed off the top of the display space and recirculated so that it does not spill over the front or side walls of the case. By circulating the air within the display space the temperature of the air is maintained substantially uniform throughout, whereas the refrigerating efficiency of the case is maintained very high by elimination of losses due to the spilling of the cold air from the case.
. the temperature of the air within the display have been provided heretofore with an open refrigerated well. However, the cold air in such constructions 4is not circulated and therefore tends to settle to the bottom of the well with the result that the lower portion of the well is maintained at a much lower temperature than the upper portion thereof. Such constructions are therefore unsatisfactory for use in the preservation and display of meats and dairy products.
In accordance with my invention these objections and disadvantages of constructions of the prior art are overcome and open type refrigerated cases are provided wherein objectionable condensation of moisture on the products being displayed is avoided while little or no cool air is lost by spilling thereof over the walls of the case. At the same time the air within the display space is circulated so as to maintain substantially uniform temperatures throughout the display space.
In the preferred embodiments of my invention shown in the figures of the drawings and hereinafter described, the case is provided with a display space which is closed at the bottom and about the sides but is open at the top and means are provided for withdrawing air from the upper portion of the display space and serve to pass it over refrigerating means back into the lower porsubstantially uniform figures of the accompanying drawing:
l Fig. 1 is a perspective of a preferred type. of display case embodying my-invention.
Fig. 2 is a vertical sectional view ofthe construction illustrated in Fig. 1.
Figs. 3 and 4 are diagrammatic sectional views of alternative constructions embodying my invention.
In that form of my invention illustrated in Figs. 1 and 2 of the drawings, the display case is provided with a front wall 2, end walls 4 and a rear wall 6. These walls extend upward from the bottom 8 Aof the case to form a bin having a display and storage space I0 which is closed at the bottom and sides and open at the top. As shown in the drawings, I prefer to form the upper portion I2 of the front wall 2 with a glass section so that articles on display within the space' I 0 may be readily observed by the customers. lThe lower portion of the front wall as well asthe I bottom l. the end walls 4 and the rear wall 6 are provided with suitable thermal insulation to prevent heat loss through the sides and bottom of the case.
Within the display space are located article may be circulated so as to pass upward through the openings in the shelf and into contactwith the articles supported thereon.
The rear wall 6 of the case extends upward a forwardly extending projection I6. The front edge of the projection preferably extends downwardly at I6 to support illuminating means such as the fluorescent lights 20. Refrigerating means, shown as a refrigerating coil 22, are supported by the rear wall 6 beneath and adjacent the forwardly extending projection I6. A baille member 24 is located in front of the refrigerating coil and is spaced from the rear wall 6 so as to provide an air circulating duct;k 26 through which air cooled by the coil 22 may pass downward into the lower portion of the display space I0. The lower portion 28 of the baille 24 is preferably provided with openings 30 through. which air may pass from the duct 26 into the display space above the shelf. or article supporting means I4. At the same time a portion of the air flows downwardly through the lower outlet opening 32 of the duct 26 into the space 434 beneath the shelf I4 and above the bottom 8 of the case. This air then circulates forward toward the front of the case and upward through the openings in the shelf so as to be distributed over the articles being preserved and displayed. A drip pan 36 may be located below the outlet opening 32 of the duct 26 to collect any condensate which accumulates on the baille 24 and the lower portion 26 thereof so as to conduct such moisture to a drain 36 in the bottom of the case.
An important feature of my invention`and one which serves to prevent cool air from spilling over the front I2 of the case resides in the warm air bale 4i)l which extends downward from the portion I8 of the projection I6 at the top 'of the back of the case. The lower edge 42 of the warm air baille 40 is located at or below the level of the'upper edge 44 of the front wall of the case. In this way the warm air baille cooperates with the baille 24 to form a 'continua tion 46 of the air duct 26 and to present 'an air inlet 4i!l which is located substantially at or below the level of the upper vedge of the front wall of the case. A thermo-syphon is thus edge 44 of'the front wall the operation of the case is unsuitable for use in the preservation of f meats and dairy products because of the deposition of moisture on the articles on display and excessive accumulation of moisture in the form of ice-on the coils and because of the loss of cold air by spilling thereof over the front wallof the case. Generally, therefore, I prefer the lower' edge 42 of the warm air baille to be located at or somewhat below the level oi' the upper edge of the front of the case. The thermo-syphon then skims off the warmest portion of the cool air from the upper portion of the body of cold air maintained and circulated within the display space and but little, if any, warm moist air from u coil.
higher than the front wall and is provided with illustrated'in Figs. 1 and 2 resides in the loca- A characteristic feature of the construction tion of the refrigerating coil 22 at an elevation above the level of the upper edge 44 of the front wallvof the display space. With this construction the height of the thermo-syphon and the column of cool air in the air duct 26 is suillciently does mingle with the cool air returning to the rents of ,sufficient velocity to prevent moist air refrigerating coil is' cooled thereby so that the coil acts as-a conditioning element which regulates the moisture content of the air and serves to remove excess moisture therefrom. This reg ulation of the moisture content of the air prior to its passage into contact with the articles beingdisplayed together with the creation of air curfrom coming into contact with the cooled articles, insures thefpreservation of the articles in a cooled but dry condition despite the fact that the case is open to the atmosphere at the top.
In some instances I have found it desirable t0 supplement the refrigerating coil by providing a formed by means of which the air passed over While the lower edge 42 of the warm air baiev 40 may .be spaced a short distance above the upper edge 44 of the front wall of the case, I
have found in practice that this distance should not exceed an inch or so for the most eiilcient operation of the case, and when the edge 42 is as much as four inches above the level of the second cooling coil 50 located adjacent the bottom of .the display space beneath the shelf I4. However. for most purposes such a supplementary coil is not necessary.
By forming the warm air baille 40 of material having low heat conductivity the deposition of moisture thereon is reduced to a minimum. However, I generally provide a drain gutter 52 at -the lower edge of the warm-air baille A4I! to conduct any condensate formed to the end of the case so lthat 'it cannot drip onto the articles being displayed. A Itag'molding 54 is positioned adjacent the lower edge of the transparent portion I2 of the front wall of the case for indicating the price of various articles supported on the shelf I4.
While I prefer to employ a construction such as that shown in Figs. l `and 2, in which Ithe -air is circulated by a thermo-syphon action. theair may be positively circulated through the display space, 'as illustrated by the constructions shown in Figs. 3 and 4.
In the construction of Fig. 3 the display case is generally similar to that shown in Figs. 1 and 2, but a blower or fan 60 is located beneath the forwardly projecting portion 62 ofthe rear wall 64 of the case so as to draw air positively upward through the portion 66 of the air duct 68 land case are all of substantially the same height. The
rear wall 80 of the case is provided with a baille member 82 which cooperates therewith to form an air duct 84 for circulating the air within the display space 8B. The upper end of the air duct communicates with the display space through the inlet openings 88 located below the upper edge of the rear wall and at or below the level of the upper edges of the other walls of the case. The lower end of the duc-t 84 communicates with the lower portion of the display space through the outlet opening 90 and a fan or blower 92 is located adjacent the outlet opening to draw' air downward through .the air duct 84 and Acirculate it toward the front of the case beneath the shelf or article supporting means 94.
In each of the forms of. my invention illustrated in the drawings the air circulated through the in Fig. 4 diners from that transverselyof said section and spaced above said bottom to denne a chamber, an air duct having an upper air inlet opening extending along one portion `of the sides adjacent the plane of the lowest portion of the open top of said section and an air outlet communicating with said chamber, means including a motor-driven fan for insuring a positive downward flow of air through said duct to skim off air from the top of the section and discharge it downwardly to said chamber, said perforate shelf constituting not only a supporting means for goods but also means to distribute air display space is drawn from the upper portion of the display space and passed over refrigerating means into the lower portion of the display space, thereby insuring substantially -uniform temperature conditions throughout the display space. By drawing the air from the upper portion of the display space the cool air never builds up to a level above the upper edges of the side walls of the case and therefore it does not spill over these walls and a high refrigerating efficiency is maintained.
Moreover, by drawing the air circulated over the coil and over the cooled portions of the case from the body of cool air maintained in the display space, but little, if any, warm moist air from the exterior of the case is drawn into the air circuit and the deposition of moisture on the articles be- -ing displayed and on the cold portions of the case or on the coil, is reduced to a minimum. Furthermore, if moist air from the exterior of the case' ticles on display, so that its temperature is reduced causing its moisture to be deposited on the coil rather than on the meats or other products inthe display space.
While I have illustrated and described certain preferred embodiments of my invention, it will be readily understood that the form, design', and construction of open type display cases embodying my invention may be varied considerably. Thus, for example, construction generally similar to that shown and described in the copending application of Floyd C. Lowell, Serial No. 378,503, led February 12, 1941, now Patent No. 2,290,647, granted July 21, 1942, maybe employed without using the doors which close the top of the -display space.Vv Therefore, it should be understood that the embodiments of my invention shown in the drawings and herein described are intended to be illustrative of my invention and are not intended to limit the scope thereof.
1. An open self service refrigerated display case having means for maintaining a continuous recirculation of cooled air within the contines of an open topped section thereof with minimum loss of such air or addition of outer air, said case including an element forming the bottom of said open topped section, wall structure extending substantially vertically therefrom to denne the sides of said section. a perforate shelf extending from said .chamber upwardly throughout the cross sectional area of said section above said shelf, and means for cooling the air within said section.
2. An open self service refrigerated display case having means for maintaining a continuous recirculation of cooled air within the confines of an open topped section thereof with minimum loss of such air or addition of outer air, said case including an element forming the bottom of said open topped section, wall structure extending substantially vertically therefrom to define the sides of said section, a perforate shelf extending transversely of said section and spaced above said .bottom to define a chamber, an air duct having an upper-air inlet opening extending along one portion of the sides adjacent the plane of the lowest portion of the open top of said section and an air outlet communicating with said chamber, means including refrigeratng coils Within said duct and a motor-driven fan for insuring a positive downward flow of air through said duct to skim oi air from the top of the section and disincluding an element forming the lbottom of said open topped section, wall structure extending substantially vertically therefrom to define the sides of said section, a perforate shelf extending transversely of said section and spaced above said bottom to define a chamber, an air duct having an upper air inlet opening extending along one portion of the sides adjacent the plane of the lowest portion of the open top of said section and an air outlet communicating with said chamber,
' means including refrigerating coils and a motordriven fan for insuring a, positive downward ilow of air through said duct to skim off air from the top of the section and discharge it downwardly to said chamber, said perforate shelf constituting not onlya supporting means for goods but also means to distribute air from said chamber upwardly throughout the cross sectional area of said section above said shelf and inwardly directed baiiles adjacent said open top opposite said upper air inlet to direct air across said open top towards said inlet.
MALCOLM D. MACMASTE'R.
(References on following page) 7 nnmnuczs cum "The following references are o! record ln the 111e of this patent:
' UNITED STATES PATENTS Number Number Numa Data Murphy Dec. 29,l 1936 Balen Jan. 8. 1937 Gardner June 8, 1937 Gray June 14, 1938 Smith Nov. 14, 1939 Blz-eley Oct.v 29, 1940 Wolf Nov. 19, 1940 Starr Sept. 30, 1941 Nordskog Feb. 3, 1942 Caulk et al Aug. 14, 1945