US3324783A

US3324783A - Air directing grid construction

Info

Publication number: US3324783A
Application number: US456953A
Authority: US
Inventors: Lester E Hickox
Original assignee: Clark Equipment Co
Current assignee: Doosan Bobcat North America Inc
Priority date: 1965-05-19
Filing date: 1965-05-19
Publication date: 1967-06-13
Anticipated expiration: 1984-06-13
Also published as: AT279657B; GB1135589A; NO125993B; BR6679627D0; FI45700B; CH454930A; FI45700C

Description

June 13, 1967 1.. E. HlcKox AIR DIRECTING GRID CONSTRUCTION Filed May 19, 1965 FIG. 3

. a: 12% a E 2 E E E; M/ an E ii i a INVENTOR R E. HCKOX LESTE M4 B fl m ATTORNEY United States Patent 3,324,783 AIR DIRECTING GRID CONSTRUCTION Lester E. Hichox, Niles, Mich, assignor to Clark Equipment Company, a corporation of Michigan Fiied May 19, 1965, Ser. No. 456,953 5 Claims. (Cl. $36) This invention relates to an air-directing grid construction, particularly to such a construction employed in a refrigerated display case.

One type of refrigerated case commonly used in food stores for the display and self-service sale of foods and other products is constructed with an open top through which access is had to the products contained therein The interior of the case and the products therein are cooled by air which is circulated over refrigerating coils or the like and through duct means in a wall of the case and across the open top to duct means in the opposite wall, and thus back to the refrigerating coil for another cycle. In passing across the top of the case, the greater density of the cold air causes it to move downwardly into the interior of the case to cool the products therein and maintain them at the desired temperature. In its passage across the top of the case, the stream of refrigerating air tends to spread out or diffuse, as it loses the initial velocity of its discharge from the one wall, and becomes affected by the higher temperature of the ambient air. So far as this results in the refrigerating air flowing down into the case, it is not objectionable, since such air is sooner or later returned to the recirculating stream of air. The air in the stream flowing across the open top of the case, however, particularly at the upper portion or layer thereof, mingles and intermixes with the ambient air. It is thus lost from the recirculating air, being replaced by air necessarily at a higher temperature. In addition, the air in the upper portion of the stream tends by reason of its velocity to cause turbulence as it impinges on the ambient air, resulting in excessive undesirable intermixing of the warm ambient air with the recirculating refrigerating air, thus additionally raising the temperature of the latter. The refrigerating capacity of the case must therefore be sufficient to cool the recirculating air through a greater temperature differential or gradient than if the two factors of replacement of lost cold air by warmer air, and increased contact between the cold air and the warmer ambient air due to turbulence, were not present. The relative humidity of the stream of air is also increased by its being warmed and the entrainment of warmer air therein, which results in faster and heavier deposit of frost on the refrigerating coils, with consequent lowered efiiciency thereof. This in turn requires more frequent defrosting, interrupting the refrigerating operation and requiring more frequent operation to restore the desired temperature. Additional lowering of refrigeration efliciency is thus brought about. To the extent that the causes of warming of the refrigerating air can be eliminated, the cooling capacity of the case is unnecessarily high, and to the extent that frosting can be avoided, the efficiency of the case is needlessly reduced. The present invention provides means which greatly reduces the loss of refrigerating air in passage across the open top of a refrigerated case, and rise in temperature of refrigerating air by contact and intermingling with the ambient air.

According to the invention, a grid is provided at the outlet through which the refrigerating air is discharged across the top of the case, the grid providing a plurality of passages each receiving a portion of air and discharging it in a direction determined by the orientation of the passages. The directionalization of the air reduces the diffusion and consequent loss of refrigerating air and excessive intermingling with ambient air. In addition, the air is discharged in a number of layers, the uppermost of which may be made to move at the lowest velocity, so as 3,324,783 Eatented June 13, 1%67 ice to further minimize contact and intermingling with the ambient air by reducing turbulence in the flow across the case. To obtain desired uniformity of the refrigerating air stream along the entire length or width of the case, means are provided for restricting or impeding the flow of the refrigerating air before it reaches the grid so that the volume and velocity of the discharged air is substantially uniform along the entire length of the outlet. The impeding or restricting means may take various forms, such as a restriction in the discharge portion of the duct means, or a grille or like perforated eiement at the outlet. In many cases, at least, it is preferable to employ both forms of air-impeding construction. In cases where uniformity of the discharge pressure along the entire length of the outlet is not a major consideration, or in cases where the duct is not of great extent, the air-impeding construciton may be eliminated. The topmost layer or stratum of air may be reduced in velocity in various ways, a simple one being the provision of a deflector or vane directing a considerable portion of the air through the lower portion of the grid, so that the pressure and hence the velocity of the air flowing through the upper grid portion are brought below those of the air passing through the lower portion. The invention is not restricted in application to refrigerated cases or the like, but may be employed in any construction involving the discharge of air or other fluid under pressure from duct means into or across an open space when it is desired to minimize diffusion and intermingling of the discharged fluid into and with the atmosphere of such space.

It is an object of the invention to provide a grid construction for directin air or other fluid discharged under pressure from duct means, which minimizes diflusion of the fluid and intermingling of ambient fluid therewith.

It is another object to provide a directing construction for air or other fluid discharged from the outlet of duct means under pressure, which imparts a predetermined direction to the discharged air or other fluid to minimize diffusion thereof, and provides uniform fluid pressure along the entire length of the discharge outlet.

Another object is the provision of a directing construction for air or other fluid discharged under pressure from the outlet of duct means, which effects discharge thereof in layers with the top layer moving at low velocity. further object'is the provision of a construction for directing air or other fluid discharged under pressure from duct means, which effects discharge thereof in a plurality of layers allowing discharge in controlled proportions through different portions of the outlet.

Another object is the provision of an open-topped refrigerated case with a grid construction for imparting a predetermined direction to refrigerating air forced in a stream across the open top of the case, to minimize loss and warming of the refrigerating air.

Another object is the provision of an open-topped refrigerated case in which refrigerating air is forced across the open top, with a construction for imparting a predetermined direction to the air in order to minimize warming of the refrigerating air stream, and which also assures uniform distribution of the air along the entire length of the case.

Another object is the provision of an open-topped case refrigerated by refrigerating air passed over the top thereof with an air-directing construction which divides the air into a plurality of layers allowing control of relative velocities of the layers and of the proportion of the air moving in each layer.

Other and further objects, advantages and features of the invention will be apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a cross-sectional view of an open-topped refrigerated case incorporating the grid construction according to the present invention;

FIGURE 2 is an enlarged fragmentary view of a portion of the grid construction shown in FIG. 1;

FIGURE 3 is a fragmentary front elevational view of the grid construction as shown in FIG. 2; and

FIGURE 4 is a perspective view of a modification of the grid construction shown in FIG. 1, on a slightly enlarged scale.

Referring first to FIG. 1 of the drawings, there is shown a refrigerated open-topped case C defined by a pair of end walls IE, only one of which is shown, between which extend parallel front and rear walls F and R, rising vertically from a suitable base B. The walls and base are, as in common, of suitable heat-insulating construction. Within the case is mounted a container or well W the bottom of which is spaced above the interior of the base to define a refrigerating chamber divided into front and rear portions by a suitable partition P located between the front and rear walls. A fan, blower, or other suitable air-moving means A is mounted adjacent an opening in the partition to move air from the front chamber portion over and past suitable air-cooling means M, such as the evaporating coil of a refrigerating apparatus, located in the rear portion of the chamber. A plurality of air-moving means A and refrigerating means M may be employed in the case. The front wall and rear wall 11 of the well W are spaced from the front and rear walls F and R of the case to define therewith

vertical ducts

12 and 13 each in communication with the refrigerating chamber. The well W may be formed of any suitable material, such as sheet metal, which may be readily formed to appropriate shapes, and may have suitably supported therein any appropriate support or supports for merchandise, such as that indicated as S.

The top of the duct 12, defined between the front wall 10 of the well and the front wall F of the case, is closed in any suitable manner, as by etxension of the upper edge of the wall 10 to the top of the front wall F. The upper portion of the well wall 10 is slotted or otherwise apertured as at 14 .to provide for passage of air into the duct 12. Air is drawn through the apertured portion and downwardly through duct 12 by the fan or other air-moving means A, and passed through the partition aperture and over the refrigerating means M to flow upwardly in the rear duct 13 defined between the well wall 11 and rear wall R of the case. At its upper portion, the wall 11 is formed with an offset rearwardly, or inwardly of the duct, for a horizontal distance somewhat less .than the thickness or depth of the grid to be employed, and for a vertical distance slightly greater than the height of the grid. The vertical portion of the offset serves as a grille 15, being slotted or otherwise perforated as at 16. The upper end of the grille 15 is connected by a horizontal portion 17 to a suitable part of the case, as to the rear of a tag molding subassembly or structure T secured to a forwardly extending portion of the case rear wall R, and projecting downwardly to slightly above the level of the upper edge of the grille 15. The portion 17 is shown herein as formed with an upturned flange secured by screws or other fastening means to the structure T. The tag molding structure or subasssembly has a forward face inclined downwardly and forwardly from the upper portion of the case, provided withknown means to hold identifying or price tags. The tag molding structure T in this case in effect provides a forwardly projecting hood at the upper end of the grille, but it will be understood that this is not necessary to the invention.

The grille 15 preferably extends substantially throughout the length or breadth of the case C, as do .the

ducts

12 and 13, and serves to so impede or restrict the flow of air out of the duct 13 as to result in a substantially 4 uniform pressure along the entire length of the grille, so that the air passes therethrough in substantially the same volume and at substantially the same velocity at any point along its length. Although the grille 15 is disclosed herein as integral with the rear wall 11 of the well W, it will be understood that it might be formed as a separate part, and secured in place in any suitable manner.

Either instead of or in addition to the grille 15, air impeding means may be provided in the rear duct 13 providing a restricting slot 18 or similar aperture or orifice, or a longitudinally extending series of such apertures. In the present instance, a single, full-length restricting slot 1% is shown as provided by a pair of longitudinally extending angle members 19 of sheet metal or the like secured to the opposite faces of the duct 13. It will be evident that other means might be substituted for this purpose, as for example a longitudinally extending channel member arranged with its web spanning the Width of the duct 13 and provided with suitable apertures. The restriction of air flow through the duct by this means causes a back pressure which results in an even distribution of the air along the length or breadth of the duct 13, so that the air discharge pressure and volume is not greater at points in alignment with the fan or fans or other air moving means than at other points along the length of the case. In many instances, either the grille 15 alone or the restricting orifice structure alone is sufficient to obtain the desired uniform distribution, while in other instances the use of both of these air impeding means is preferable to obtain the desired result. In instances in which it is not important that uniform air distribution be achieved, no air impeding means need be employed, and in such case an opening may be provided in the well wall 11, the grille 15 being eliminated.

The air directing grid proper is indicated generally at 20 and is shown herein as comprising a plurality of walls or partitions 21 in two rectangularly related sets, intersecting to define open-ended cells or passages 22 of square section. The passages have a length corresponding to the thickness of .the grid 20, as best evident from FIGS. 1 and 2. It will be understood that the arrangement and cross-sectional configuration of the passages may be changed from those shown and described, if desired. The grid may be formed of any suitable material, an appropriate synthetic plastic material providing a light, inexpensive and attractive grid. In the illustrated instance, the grid 20 is mounted adjacent the forward face of the grille 15 with one side or face thereof engaging the grille. If .the grille 15 is omitted, the grid 20 is similarly mounted in the opening defined in the rear wall 11. The air flowing from the duct 13 enters one end of each passage 22 of the grid, and is discharged from the other or forward end in the direction corresponding to the direction in which the passages extend. In .the present disclosure this direction is horizontal, toward the front of the case C. Any suitable means may be employed for mounting the grid 20 in the desired position, those shown comprising a series of Z-shaped clips 23 secured to the wall 11 of the well W and providing a vertical lip projecting slightly above the level of the bottom of the grille 15 and spaced forwardly therefrom. The bottom portion of the grid 20 is received between the grille and the lips of the clips, and the upper portion of the grid then swung rearwardly, a slight clearance being provided between the upper horizontal connecting portion 17 of the grille 15 and the top of the grid. A series of longitudinally spaced spring detents 24 are mounted in this upper portion 17, and engage in correspondingly located apertures (not shown) formed in the top partition 21 of the grid, thus removably securing the grid in place. Of course, other means might be employed for mounting the grid if desired.

Refrigerating air is discharged through the grid 20 in the direction of the passages 22, which in this instance are arranged horizontally, and by reason of the directionalizing effect of the grid flows in a stream across the top of the case with a minimum of diversion from and diffusion of the stream, particularly in the upward direction. 'In the downward direction, .the cold refrigerating air tends on convectional principles to move downwardly out of the stream. This is not only unobjectionable, however, but desired, since the flow is into the well so as to maintain the products contained therein at the desired refrigerated temperature, and sooner or later this downwardly flowing air returns to the stream. The air flowing across the top of the case enters the front duct 12 through the slots or apertures 14, and then is recirculated by the air moving means A over the refrigerating means M and through the duct 13. The air which does not descend into the interior of the case serves to shield the air and products in the well against the warming effects of the air above the open top of the case. In the present case, the inlet to the front or return duct 12 is illustrated as at a lower level than the grid 20. Air issuing horizontally from the grid is drawn downwardly by gravity and by the suction in the duct 12, to flow tluough the apertures 14 into the duct for recirculation. Air in the well W is drawn upwardly by the suction. The action would be similar if the level of the apertures 14 was the same as or higher than that of the giid W.

In addition to imparting direction, the grid 20 has a stratifying effect on the refrigerating air, which issues therefrom in a plurality of superimposed layers. As explained herebeiow in connection with the construction of FIG. 4, the refrigerating air discharged from the grid may be controlled so that the top layer has less velocity than any lower layer, and thus creates less turbulence in encountering the warm air above the case. The result is that there is less contact and intermingling of the refrigerating air and the Warmer overlying air than would be the case with higher velocity air, and less entrainment in the refrigerating air stream of the warmer room air. Rise in temperature of the refrigerating air stream due to contact with the warmer air and replacement of refrigerating air by warmer air is thus reduced to a minimum. Such minimization of temperature rise of the refrigerating air is advantageous not only in reducing the required capacity of the refrigerating apparatus, but in reducing frost formation on the refrigerating means. Such frost formation is undesirable because it reduces the efiiciency of heat transfer, and also requires periodic defrosting with its accompanying Warming of the case and its contents. Consequently more frequent operation of the refrigerating apparatus is required to restore and maintain the desired product temperature, with a resultant lowering of efficiency.

The modified grid construction illustrated in FIG. 4 is substantially identical to that shown in FIG. 1, except that a diverting or turning vane is added in the outlet duct 13 at the discharge opening. The grid 20 is provided as in the construction in FIG. 1, being held by the clips 23 and detents 24 in the outlet or discharge opening, which as in FIG. 1 is illustrated as defined by the rear- Wardly offset grille 15, although the grille may be omitted as previously explained. The remainder of the construction of the case C of FIG. 4 is substantially the same as that of the case in FIG. 1, except for the turning vane as already mentioned. This vane is indicated generally at 30, and comprises a generally horizontal portion 31 which extends transversely of the duct from closely adjacent the grille at a level intermediate the height of the grille or the grid 20, and has depending from its rear edge an integral vertical portion 32 dividing the width of the duct 13 into two parts. The vertical vane portion 32 is mounted in any appropriate manner in a position parallel to the opposite walls of the outlet duct and extending from the horizontal portion 31 toward the source of air flow. In the present instance, bolts 33 or like fasteners employed at intervals extend through the vertical portion 32 and the inner face of the rear wall R of the case C, spacers 34 being provided between the vane and the rear wall R. The horizontal portion 31 of the vane directs through the lower portion of the grid 20 that part of the air passing through the outlet duct 13 which flows between the vertical portion 32 and the front wall of the duct, i.e., the rear wall 11 of the well W. The air discharged through the portion of the grid 20 above the horizontal vane portion 31 is that which passes between the vertical portion 32 and the rear wall of the duct, i.e., the inner face of the rear wall R. The spacing of the vertical vane portion 32 between the front and rear walls of the duct 13 determines the proportions of the air discharged through the upper and lower portions of the grid. The vane 30 concentrates a greater proportion of the refrigerating air through the lower part of the grid 20 than would otherwise flow through such lower part, .to assure that the interior of the case and the contents will be maintained at the desired temperature. Normally it is employed only in the case of low temperature refrigerated cases, usually called freezers and used for frozen foods, ice cream, and like products which must be maintained at below-freezing temperatures. It is not intended to imply, however, that the vane is required in all low-temperature refrigerated cases, or that it may not be used in other refrigerated cases or under other conditions, if desired.

By diversion through the lower portion of grid 20 of a greater proportion of the refrigerating air than would otherwise pass therethrough, the proportion flowing through the upper grid portion is of course reduced. The pressure and hence the velocity of the air passing through the upper portion of the grid is therefore reduced, so that the top layer of the air stream flowing over the top of the case moves more slowly than any lower layer. The advantages of this low velocity of the top air layer have been explained hereinabove. It will be evident that the division of the air as between the upper and lower portions of the grid by the vane 30, and thus the pressure and velocity of the different layers, may be varied by the location of the vane portion 32 between the front and rear walls of the duct 13, and that this may readily be adjusted as desired. The same principle may be applied in the use of more than one turning vane, if desired.

The use of the disclosed grid construction is not limited to refrigerated display cases, as has been pointed out hereinbefore, since it may be employed in connection with the discharge of air or other fluid under pressure from a duct through which it flows, in order to obtain the benefits of the directionalizing and stratifying effects of the grid construction as explained hereinabove in connection with the specific incorporation of the grid construction in a refrigerated open-topped display case.

It will be understood that the embodiments of the invention illustrated herein are exemplary of the inventive concept and that the invention is not limited to such embodiments, since modifications and variations thereof, some of which have been described and suggested hereinabove, may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. A refrigerated display case comprising a bottom, walls extending upwardly from said bottom to define a product-containing space, a refrigerating fluid duct extending in at least two of said walls, an aperture in one of said two walls for discharge of fluid from said duct, an aperture in the other of said two walls for return of fluid to the duct, means for moving fluid through said duct and from said discharge aperture across and through said space through said return aperture, means for effecting substantially uniform pressure and distribution of fluid along said discharge aperture, and means for directing the fluid upon discharge from the duct to minimize diffusion and intermingling thereof with ambient atmosphere, said directing means comprising a grid disposed at the discharge aperture having a plurality of passages therethrough each extending in a predetermined direction and receiving a portion of the fluid passing through the discharge aperture and discharging said portion of fluid in said predetermined direction, and said uniformity-effecting means comprising a plate-like element Within the duct adjacent said grid having perforations communicating With said grid passages.

2. A refrigerated display case as defined in claim 1, in which said plate-like element comprises substantially flat grille means at the discharge aperture substantially immediately inwardly of said grid.

3. A refrigerated display case as defined in claim 1, including means in the duct to direct different portions of through different portions of the discharge aperture.

4. A refrigerated display case as defined in claim 1, in which said fluid is air.

5. A refrigerated display case as defined in claim 1, in Which substantially all the passages are substantially parallel to each other.

References Cited UNITED STATES PATENTS ROBERT A. OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,324,783 June 13, 1967 Lester E. Hickox It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 2, line 16, for "construciton read construction column 3, line 16, for "in" read is line 39, for "etxension" read extension line Q4, for "subasssembly" read subassembly column 5, line 68, for "or" read of column 7, line 16, before "through""insert fluid Signed and sealed this 2nd day of January 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer I Commissioner of Patents