Air circulation unit for refrigerated cases

An air flow circulation device for use in refrigerated display cases. The device is used to provide substantially vertical cooling air flow within refrigerated cases, particularly cases having shelves. The device distributes refrigerated air through the case and particularly to upper and middle shelves.

FIELD OF INVENTION 
This invention relates generally to refrigerated food display cases. More 
specifically, this invention provides a device for improving air flow in 
refrigerated display cases, particularly when shelving units are placed 
within such cases. 
BACKGROUND OF THE INVENTION 
Refrigerated display cases are a common feature of modern grocery stores. 
Typical refrigerated cases have a bottom and four lower sides defining a 
well, the well serving as a settling area for cool, refrigerated air, and 
as a display area for food products. Many modern refrigerated cases also 
have a tall back and top overhang with an open front to allow customers to 
view, inspect, and retrieve food items. 
A refrigerated case having an open front requires carefully regulated air 
flow to maintain cool temperatures within the case. Cooled air spilling 
from (or room temperature air being drawn into) the case requires extra 
cooling. More importantly, improper air flow patterns may result in case 
temperatures, or temperature variations, which violate food regulations 
and/or result in spoiled food. 
In a typical open-front case, air is pulled through a front or bottom well 
vent, drawn over a cooing coil within the case, pushed through a channel 
within the case back, and discharged either through the case back, the 
case top overhang, or both. Pulling air from the well bottom or front and 
discharging it through the case back and/or top creates a curtain of 
cooled air. Ideally, this air flow pattern neither discharges cool air 
into the room nor pulls warm room air into the case. 
Competitive pressures have forced grocers to display (and sell) more goods 
per square foot. In response to such pressures, grocers have installed 
shelving units within refrigerated cases, the shelves being typically 
placed toward the back of the well. Such shelves create more horizontal 
shelf space. However, the use of such shelves may create cooling problems 
within the cases. 
Many cases are not designed for use with shelves. Also, the food displayed 
on the shelves requires cool air to maintain safe temperatures. Many cases 
are incapable of maintaining proper temperature at the upper and middle 
shelves. Furthermore, the presence of the shelves themselves creates 
problems as upper shelves shelter lower shelves from descending cooler air 
and lower shelves shelter upper shelves from circulating lower air. 
One approach to more evenly distributing refrigerated air over shelves 
positioned in a case is essentially a re-building of the cases. One 
re-building method in use increases the number of fans, so as to boost the 
total air flow up through the case back and out the top overhang. This 
increased air flow descending from the case overhang can increase the 
cooling of upper shelves. In cases where air spills in through back vents 
in the case, the vents have been removed by replacing the vents with solid 
sheet metal. By removing the back discharge vents, more air is directed to 
the top overhang discharge vents. Again, this directs more cooling air to 
upper shelves. 
Adding fans to the case itself and/or blocking vents requires significant 
re-building of the case at considerable expense. This can require 
significant down time, lost sales, and often voids the manufacturer's 
warranty for the case. Adding fans and redirecting air through the case's 
air passages also has not solved the problem of poor cooling in middle 
shelves. 
SUMMARY OF THE INVENTION 
The present invention is an air flow circulation device for use in 
refrigerated display cases and particularly cases with shelves. More 
specifically, the device improves air circulation, especially to 
intermediate shelves. 
A device according to the present invention includes a fan or other device 
for blowing air substantially vertically upward and a structure for 
supporting the fan to draw refrigerated air from the well of the case. A 
preferred embodiment fits within a four foot refrigerated case section and 
has fans sized so as to provide about 37 to about 62 cubic feet per minute 
per linear foot of refrigerated case. A most preferred embodiment is about 
30 inches long, and has three A.C. box fans, each having a capacity of 
about 37 cubic feet per minute. 
The air flow circulation device has been found to provide cool air flow for 
shelves located high up in the case. The present invention has also been 
found to provide cooling air flow for all shelves in a suitable shelving 
unit, including middle shelves often sheltered from upper and lower air 
flow in conventional refrigerated cases, including those modified as 
described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates a preferred embodiment of the present invention. Shown 
is a refrigerated case 20 having a removable shelving unit 22 (shown in 
phantom) and an air flow circulation unit 24. Refrigerated case 20 
typically has air taken in through front air intake vents 50 located in a 
front lip 48, which flows downward as indicated at 70 and through bottom 
channel 35. Air at 72 is pulled through a cooling fan 40, forced through a 
cooling coil 42, and further forced up within a passage or channel 57 
within case back 56, where some air may be discharged through back 
discharge vents 44. The remaining air is forced further up as indicated at 
76, then forward, through a top overhang 36 as indicated at 78, and down 
through top overhang discharge vents 46. The cooled air cascades down 
through case 20 and is ultimately collected through front air intake vents 
50, thereby creating an air curtain. 
Refrigerated case 20 has a bottom portion generally referred to as a well 
38, defined by front lip 48, sides (not shown), and the lower portion of 
back 56. Case 20 further has a false bottom 32 over a bottom 34, used to 
provide varying depth of goods and drainage. Refrigerated cases vary in 
design, with some having no back discharge vents 44 and others having air 
intake from within well 38 or bottom 34 rather than, or in addition to, 
front air intake vents. 
The shelving unit 22 shown has vertical supports 52, sides 58, an upper 
shelf 26, a middle shelf 28, and a lower shelf 30. In FIG. 1 it is evident 
that middle shelf 28 is partially blocked from upper cooler air flow by 
upper shelf 26 and partially blocked from lower cooler air by lower shelf 
30. Further, the tendency of heated air to rise combined with the location 
of upper shelf 26 compounds the problem. Specifically, heated air tends to 
pool in the space occupied by upper shelf 26, causing temperatures warmer 
than desired for refrigerating food. 
Air flow circulation unit 24 having an air flow fan 54 is illustrated 
resting in well 38 on false bottom 32. Refrigerated air is drawn from the 
well by air flow circulation unit 24 as indicated by arrows 80 and forced 
upward into case 20. 
Shelving unit 22 is shown being open to air flow through the shelf back, 
enhancing cooling of the shelves when used in conjunction with air flow 
circulator 24. That is, lower shelf 30 is located forward of middle shelf 
28 which is located forward of upper shelf 26. Such an arrangement of 
shelves channels air flow upward to lower shelf 30, middle shelf 28 and 
upper shelf 26, indicated by arrows 82, 84 and 86 respectively. 
FIG. 2 illustrates air flow circulation unit 24 setting in refrigerated 
case 20, the case 20 being shown in phantom. Air flow circulation unit 24 
is powered via a conventional power outlet by power cord 60 and is able to 
power another unit through outlet 64. Air through unit 24 is pulled 
through the air space beneath the unit provided by standoffs 66. 
Protection against finger injury by fan blades is provided by top grills 
62. 
FIG. 3 illustrates an exploded view of a preferred embodiment of an air 
flow circulation unit in accordance with the present invention and 
designated 120. Unit 120 includes openings 174 and box fans 170, each fan 
having a supply side 178 and discharge side 180. Top grills 162 provide 
finger protection from fans 170 as does bottom grill 172. Top grills 162 
are of conventional design, and can be made of perforated metal or heavy 
gauge metal wire. Bottom grill 172 is of conventional design also, and can 
be made of sheet metal having perforations to allow for air flow. The body 
of air flow circulator 120 is formed from sheet metal in a rectilinear box 
having a top 182, front 184, sides 186, and back (not shown). Air is 
pulled in through bottom grill 172 by fans 170, and forced out through 
openings 174 and top grills 162. Power to fans 170 is provided by plug 
168, power cord 160, and wiring 176. Power may be provided in turn to 
another unit through outlet 164. 
While any number of fans may be used within the scope of the invention, the 
preferred embodiment has three fans. Three fans have been found to provide 
air flow at both ends and the middle of an air flow unit, providing 
relatively uniform upward air flow. In a most preferred embodiment of the 
invention, the fans are sized to provide air flow of about 37 to about 62 
cubic feet per minute per linear foot of refrigerated case. Air flow 
substantially less than the lower limit has been found to insufficiently 
cool upper shelves of shelving units. Air flow substantially greater than 
the upper limit has been found to spill air out of the case and/or draw 
ambient air into the case. A most preferred embodiment of the invention is 
30 inches long, suitable for installation into a four foot refrigerated 
case section. This embodiment of the invention has three fans and 76 cubic 
feet per minute capacity. A preferred embodiment utilizes A.C. fans, 
compatible with plugging the unit into A.C. outlets in or near 
refrigerated cases or on an adjacent unit. 
An alternative embodiment, not shown, utilizes a single fan, and discharges 
air substantially vertically upward through multiple discharge vents 
disposed along the top of the air circulation unit. 
In the experiments tabulated below, an existing refrigerated case was 
fitted with an air flow circulator and a shelving unit having three 
shelves. The "bottom" space is below the lower shelf. No additional 
cooling capacity other than the air-circulator of the present invention 
was added. As can be seen in the results, temperatures were significantly 
reduced in the middle and upper shelves. A typical maximum temperature 
allowed by state codes is 45 degrees F. for many food products. As is 
demonstrated by the data, middle and upper shelf temperatures are 
significantly above this maximum without installation of the air flow 
units. With addition of the units, shelf temperatures become both lower 
and more uniform. 
______________________________________ 
Experimental Results 
______________________________________ 
Experiment 1; 
Refrigerated case: Hussman PH 
Shelf Without Air flow 
With Air flow 
Circulator Circulator 
Upper 59-60 degrees F. 
39-40 degrees F. 
Middle 49 degrees F. 39-40 degrees F. 
Lower 41 degrees F. 41 degrees F. 
Bottom 38-39 degrees F. 
38-39 degrees F. 
Experiment 2: 
Refrigerated case: Kysor Warren HZV 
Shelf Without Air flow 
With Air flow 
Circulator Circulator 
Upper 55-57 degrees F. 
43-44 degrees F. 
Middle 51-53 degrees F. 
44 degrees F. 
Lower 47-49 degrees F. 
44 degrees F. 
Bottom 44-45 degrees F. 
46-47 degrees F. 
______________________________________ 
Numerous characteristics and advantages of the present invention have been 
set forth in the forgoing description. It will be understood, however, 
that this disclosure is, in many respects, only illustrative. Changes may 
be made in details, particularly in matters of shape, size, and 
arrangement of parts without exceeding the scope of the invention. The 
invention's scope is, of course, defined in the language in which the 
appended claims are expressed.