U.S. patent application number 10/086097 was filed with the patent office on 2003-08-28 for variable air curtain velocity control.
Invention is credited to Nash, Robert V. JR..
Application Number | 20030159451 10/086097 |
Document ID | / |
Family ID | 27753790 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030159451 |
Kind Code |
A1 |
Nash, Robert V. JR. |
August 28, 2003 |
VARIABLE AIR CURTAIN VELOCITY CONTROL
Abstract
A refrigeration system comprises a display case having an
exterior and an interior. A fan blows or draws air across an
evaporator coil to cool the display case. The air is blowing over a
viewing area to create an air curtain. At least one sensor obtains
environmental data, which is fed to a control unit. The control
unit communicates with the fan and adjusts the air curtain based on
the sensed environmental data.
Inventors: |
Nash, Robert V. JR.; (Niles,
MI) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
27753790 |
Appl. No.: |
10/086097 |
Filed: |
February 26, 2002 |
Current U.S.
Class: |
62/186 ;
62/256 |
Current CPC
Class: |
A47F 3/0443 20130101;
A47F 3/0478 20130101 |
Class at
Publication: |
62/186 ;
62/256 |
International
Class: |
F25D 017/04; A47F
003/04 |
Claims
What is claimed is:
1. A refrigeration system comprising: a display case having an
exterior and an interior; a coil cooling air in said display case;
at least one fan, driving air across said coil to said display
case; a viewing area in said display case, having an outlet on one
side of said viewing area that blows air from said at least one fan
to an inlet on the other side of said open viewing area that
returns air to said at least one fan; at least one sensor for
obtaining environmental data; and a control unit in communication
with said at least one environmental sensor, for controlling said
fan based on said environmental data.
2. The refrigeration system of claim 1 wherein said control unit
alters the rate of air moved by said fan based on said
environmental data.
3. The refrigeration system of claim 2 wherein said control unit
alters the angle of a fan blade of said fan.
4. The refrigeration system of claim 2 wherein said control unit
alters the hertz rating of said fan.
5. The refrigeration system of claim 2 wherein said control unit
alters the speed of said fan.
6. The refrigeration system of claim 1 wherein at least one fan
comprises at least a first fan and a second fan controlled
separately by said control unit.
7. The refrigeration system of claim 6 wherein said control unit
may control the rate of air moved by each of said fans
differently.
8. The refrigeration system of claim 1 wherein said environmental
sensor comprises a temperature sensor.
9. The refrigeration system of claim 1 wherein said environmental
sensor comprises a pressure sensor.
10. The refrigeration system of claim 1 wherein said environmental
sensor comprises a humidity sensor.
11. The refrigeration system of claim 1 wherein said environmental
sensor senses environmental data from an exterior of said display
case.
12. The refrigeration system of claim 1 wherein said environmental
sensor senses environmental data within said interior of said
display case.
13. A method of controlling air flow rates in a refrigeration case
comprising: providing a display case with a fan for driving a flow
of cooling air to separate an interior of said display case from an
exterior of said display case; sensing environmental conditions;
and controlling a fan for creating said air flow based upon said
sensed environmental conditions.
14. The method of set forth in claim 13 wherein said sensed
environmental data is taken from a location exterior to said
display case.
15. The method of claim 13 wherein the speed of said fan is
increased or decreased based upon said sensed environmental data.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a variable velocity air curtain
for a refrigeration display case.
[0002] Supermarkets and retailers of other perishable goods use
refrigerator display cases to both refrigerate and display such
goods. Generally, these display cases are simple and
unsophisticated refrigeration units that comprise a case and an
open viewing area that permits consumers to reach into the
refrigerated section of the case to retrieve the perishable item. A
curtain of air is typically blown across the viewing area from the
top of the case down to a warm air return at the bottom of the
case. The air travels to an air inlet of the return that feeds the
air back to a fan that draws the air not only into the inlet but
across an evaporator coil that cools the air. The fan is fixed in
speed, blowing a constant amount of air across the viewing area.
This air curtain serves to create a wall of air that prevents warm
air from outside of the case from entering the interior of the
case.
[0003] Given the open nature of the display case, environmental
conditions may affect the interior temperature of the refrigeration
unit. Specifically, if the temperature of a location, such as a
store, is high, the interior of the display case may also warm.
Moreover, frequent intrusion into the display cases' interior by
consumers reaching for and removing product may also affect the
temperature within the interior. Current systems have few effective
mechanisms for addressing changing exterior and interior
environmental conditions about the refrigeration display case.
[0004] A need therefore exists for a display case that may account
for these environmental conditions and cool the interior of the
display case in a cost effective manner.
SUMMARY OF THE INVENTION
[0005] The invention comprises a refrigeration display case that
employs an environmental sensor and a control unit that controls
the fans to alter the rate of air flow across the viewing area of
the display case. The refrigeration system comprises a display
case, an evaporator coil, fans, a viewing area set across the
display case, at least one sensor for obtaining environmental data,
and a control unit. The control unit controls the speed of the fans
based on the sensed environmental data.
[0006] By controlling the speed of the fans, the control unit
alters the rate of air moved across the viewing area, providing
more or less cold air depending on the sensed environmental
conditions. The control unit may adjust the rate of air by altering
the speed of the fan, altering the Hertz rating of the fan, or
altering the angle of the fan blades of the fan.
[0007] Additionally, the control unit may control more than one fan
separately. This allows the control unit to alter the rate of air
moved by each of the fans together or differently. The control unit
may receive environmental data from a wide variety of sensors. One
sensor may provide data on air pressure. Another sensor may provide
data concerning ambient humidity. Moreover, the environmental
sensor may also sense temperature. The environment may be sensed
both inside of the display case and outside of the display case.
This data is communicated to the control unit which makes a
determination as to the correct amount of air required for the
specific environmental conditions.
[0008] In this way, the refrigeration system offers an inexpensive
and efficient mechanism for accommodating the changing
environmental conditions in a supermarket or other retail
establishment. The refrigeration system has the opportunity to
obtain a wide variety of environmental data and make intelligent
decisions to control temperature within the display case. This
system may be employed practically because it may incorporate
existing sensors and computer controls.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The various features and advantages of this invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiment. The
drawings that accompany the detailed description can be briefly
described as follows:
[0010] FIG. 1 illustrates a side profile of the embodiment of the
invention, a refrigeration system.
[0011] FIG. 2 illustrates a front view of the embodiment of FIG. 1,
highlighting the open viewing area of the display case.
[0012] FIG. 3 illustrates a schematic view of the control system
used to adjust the amount of air flow across the open viewing
area.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] FIG. 1 illustrates an embodiment of the invention,
refrigeration system 10. Refrigeration system 10 comprises display
case 14, evaporator coil 18, fan panel 22, control unit 52 and
sensor 44. As known, display case 14 is cooled by evaporator coil
18. Fan panel 22 draws air from inlet 40 and blows the air across
evaporator coil 18. Air travels up rear duct 72, which distributes
some air along the direction of arrow C under shelves 60. Shelves
60 are lit by lights 64. Air not distributed in the direction of
arrow C continues to travel up rear duct 72 to top duct 68. Top
duct 68 has an outlet 36, which forces air in the direction of
arrow B across open viewing area 32. Air from outlet 36 is then
drawn to inlet 40, thereby forming air curtain 56 across open
viewing area 32. Warm air in the direction of arrow A from exterior
80 of display case 14 is thereby limited from affecting the
temperature of interior 76.
[0014] The novel aspect of this refrigeration system is the use of
environmental sensors 44, 48 and control unit 52 to control the
rate of air forming air curtain 56. Environmental sensors 44 and 48
may comprise such commonly available sensors as a temperature
sensor, a pressure sensor, a humidity sensor, or other sensor known
to affect refrigeration. Environmental sensor 44 and environmental
sensor 48 are both in communication with control unit 52, which is
programmed to alter the rate of air blowing from fan panel 22 based
on the sensed environmental data so that the desired temperature
level is maintained in interior 76 of display case 14. Sensor 44
may sense environmental data of exterior 80 of display case 14
while environmental sensor 48 may sense environmental data of
interior 76 of display case 14. Environmental sensor 48 may also
comprise a refrigeration pressure sensor sensing pressure within
evaporator coils 18.
[0015] The temperature information is used to be directly
proportional to the air rate flow. As an example, should the
temperature either outside or inside the display case increase,
then the air flow rate would also desirably increase. As the
environmental humidity increases, then the air flow rate would
desirably increase as sensed by an environmental pressure sender.
Moreover, as the pressure sensor on the refrigerant circuit
associated with the coil increases, then it can be determined that
the cooling load also increases.
[0016] It maybe desirable to decrease air flow rate to reduce the
load on the refrigerant circuit. Alternatively, if the circuit is
on a defrost cycle, it may be desirable to increase the air flow
rate to assist in defrosting.
[0017] FIG. 2 shows a front view of refrigeration system 10.
Display case 14 has outlet 36 blowing air across viewing area 32 to
inlet 40. As shown, display case 14 has no doors, permitting easy
access to products stored on the shelves of the case. However, the
present invention maybe employed on refrigeration systems having
doors or other closures.
[0018] FIG. 3 illustrates a schematic representation of the
invention. Shown are control unit 52, environmental sensor 44,
environmental sensor 48, fan panel 22 having first fan 24 and
second fan 28, evaporator coil 18 and air curtain 56. Control unit
52 communicates with environmental sensor 44 and environmental
sensor 48. Based on data from these sensors, control unit 52 is
programmed to control separately and individually fan 24 and fan 28
of fan panel 22. This separate control of fans 24 and fan 28 allows
air curtain 56 to comprise air front 82 and air front 86 that have
different rates of air flow. Fan 24 moves air across evaporator
coil 18 to form air front 82. Fan 24 controls the rate of air flow
of air curtain 56 to create air front 82. Fan 28 moves air across
coil 18 to form air front 86. Fan 28 controls air front 86 and its
movement across open viewing area 32. Thus, air current 56 may
comprise two different air fronts 82, 86 that move at different
rates. In this way, not only may each air front be controlled based
on environmental data but they may also be controlled separately to
maximize and efficiently cool display case 14.
[0019] The rate of air blown across evaporator 18 by fan 24 and fan
28 maybe adjusted by using commercially available fans. Control
unit 52 may control the angle of fan blades with known adjustable
fans. As known, by controlling the angle, volume and velocity of
air driven by the fan may be altered. Known adjustable speed fans
that may be controlled by control unit 52. Moreover, commercial
fans exist that also allow the Hertz rating of each fan to be
adjusted to thereby change the rate of air blown from the fan. An
inverter having a variable hertz rating may be used to alter the
speed of the fan motor, such as a synchronous motor, to thereby
alter the air flow rate. By controlling the inverter, the air flow
rate may be altered. One of ordinary skill in the art can envision
other techniques to permit control unit 52 to control the amount of
air blown by fans 24 and 28.
[0020] The aforementioned description is exemplary rather that
limiting. Many modifications and variations of the present
invention are possible in light of the above teachings. The
preferred embodiments of this invention have been disclosed.
However, one of ordinary skill in the art would recognize that
certain modifications would come within the scope of this
invention. Hence, within the scope of the appended claims, the
invention may be practiced otherwise than as specifically
described. For this reason the following claims should be studied
to determine the true scope and content of this invention.
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