Abstrict A refrigerated merchandiser (12) includes a display case (30) defining
a product display region having an open-front isolated from the
ambient air of the store by means of a downwardly directed inner
air curtain (55) of relatively cold refrigerated air. The amount
of airflow forming the air curtain is selectively increased in response
to a signal from a controller (80) whenever a sensor (70) detects
a disturbance in the integrity of the air curtain or from movement
in front of the display case.
Claims What is claimed is:
1. A refrigerated merchandiser comprising; a display case having
an exterior and an interior, the interior defining a product display
region having an open-front viewing area; at least one fan associated
with said display case for establishing a curtain of airflow passing
generally downwardly across the open-front viewing area of the display
region; at least one sensor associated with said display case for
detecting a disturbance in said curtain of airflow; and a controller
operatively associated with said at least one fan and said at least
one sensor, said controller controlling said at least one fan to
increase airflow in said curtain of airflow in response to said
sensor detecting a disturbance in said curtain of airflow.
2. A refrigerated merchandiser as recited in claim 1 wherein said
at least one fan comprises at least one variable capacity fan having
at least a first capacity and a second capacity, the second capacity
being significantly higher than the first capacity.
3. A refrigerated merchandiser as recited in claim 2 wherein said
at least one variable capacity fan operates at the first capacity
during steady state operation and at the second capacity in response
to said controller in response to said sensor detecting a disturbance
in said curtain of airflow.
4. A refrigerated merchandiser as recited in claim 1 wherein said
at least one fan comprises at least one variable speed fan having
at least a first speed and a second speed, the second speed being
significantly higher than the first speed.
5. A refrigerated merchandiser as recited in claim 4 wherein said
at least one variable speed fan operates at the first speed during
steady state operation and at the second speed in response to said
controller in response to said sensor detecting a disturbance in
said curtain of airflow.
6. A refrigerated merchandiser as recited in claim 1 wherein said
at least one fan comprises at least one first fan and at least one
second fan, said at least one second fan being controlled by said
controller to operate in conjunction with said at least one first
fan in response to said sensor detecting a disturbance in said curtain
of airflow.
7. A refrigerated merchandiser as recited in claim 6 wherein said
at least one first fans comprises a plurality of first fans.
8. A refrigerated merchandiser as recited in claim 7 wherein said
at least one second fan comprises a plurality of second fans.
9. A refrigerated merchandiser comprising; a display case having
an exterior and an interior, the interior defining a product display
region having an open-front; at least one fan associated with said
display case for establishing a curtain of airflow passing generally
downwardly across the open-front viewing area of the display region;
at least one sensor associated with said display case for detecting
motion in vicinity of the open-front of said display case; and a
controller operatively associated with said at least one fan and
said at least one sensor, said controller controlling said at least
one fan to increase airflow in said curtain of airflow in response
to said sensor detecting motion in vicinity of the open-front of
said display case.
10. A refrigerated merchandiser as recited in claim 9 wherein said
at least one fan comprises at least one variable speed fan having
at least a first speed and a second speed, the second speed being
significantly higher than said first speed.
11. A refrigerated merchandiser as recited in claim 10 wherein
said at least one variable speed fan operates at the first speed
during steady state operation and at the second speed in response
to said controller in response to said sensor detecting a disturbance
in said curtain of airflow.
12. A refrigerated merchandiser as recited in claim 9 wherein said
at least one fan comprises at least one first fan and at least one
second fan, said at least one second fan being controlled by said
controller to operate in conjunction with said at least one first
fan in response to said sensor detecting a disturbance in said curtain
of airflow.
13. A refrigerated merchandiser as recited in claim 12 wherein
said at least one first fan comprises a plurality of first fans.
14. A refrigerated merchandiser as recited in claim 13 wherein
said at least one second fan comprises a plurality of second fans.
15. A method of operating a refrigerated merchandiser having a
display case having an exterior and an interior, the interior defining
a product display region having an open-front viewing area and at
least one fan associated with said display case for establishing
a curtain of airflow passing generally downwardly across the open-front
viewing area of the display region, said method comprising: detecting
a disturbance in said curtain of airflow; and controlling said at
least one fan to increase airflow in said curtain of airflow in
response to the detecting of a disturbance in said curtain of airflow.
16. A method of operating a refrigerated merchandiser having a
display case having an exterior and an interior, the interior defining
a product display region having an open-front viewing area and at
least one fan associated with said display case for establishing
a curtain of airflow passing generally downwardly across the open-front
viewing area of the display region, said method comprising: detecting
motion in vicinity of the open-front of said display case; and controlling
said at least one fan to increase airflow in said curtain of airflow
in response to said sensor detecting motion in vicinity of the open-front
of said display case. Description BACKGROUND OF THE INVENTION
The present invention relates generally to refrigerated display
merchandisers of the type used in supermarkets, mini-marts, convenience
stores and other commercial establishments for displaying and merchandising
refrigerated or frozen products for sale. More particularly, the
present invention relates to open-front refrigerated display merchandisers
of the type wherein a curtain of cold refrigerated air is passed
generally downwardly across the open front product display region
of the merchandiser.
Refrigerated display merchandisers, also commonly referred to as
display cases, having open front display regions are commonly used
in supermarkets, mini-marts, convenience stores and other commercial
establishments for displaying and merchandising refrigerated or
frozen products for sale. The open front nature of such display
cases permits the consumer to simply reach into the product display
region to select and remove a product for purchase without the inconvenience
of needing to open a door to access the product. Customarily, a
curtain of cold refrigerated air is passed generally downwardly
at a set velocity across the open front of the display case to form
an invisible boundary between the product display region and the
region of the store in front of the display case. This air curtain
not only helps retain cool refrigerated air within the product display
region of the display case, thereby cooling the display product
on the shelves of the display case, but also functions to isolate,
to a certain extent, the product display region from the ambient
air within the store. Ambient air that does enter into open product
display region undesirably causes increased energy consumption by
increasing the cooling demand on the refrigeration system associated
with the display case. Further, such ambient air may also cause
a local temperature rise within the product display region sufficient
to result in an undesirable rise in product temperature that could
adversely impact upon product quality.
Significant intrusion of ambient air into the interior of the display
case occurs when consumers reach into the product display region
to select and remove product. Customers walking by the open front
of the display case may also disturb the integrity of the air curtain,
resulting in intrusion of ambient air from the store into the product
display region. To reduce the amount of intrusion and ensure rapid
reestablishment of the air curtain, it is common practice to maintain
the air curtain at a relatively high velocity. As the volume of
air being supplied to generate the air curtain is directly proportional
to the required velocity of the air curtain, maintaining a relatively
high velocity for the air curtain requires greater energy consumption,
which increases store operational costs. Therefore, it would be
desirable to reduce the energy consumption by lowering overall energy
consumption in generating the air curtain.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a refrigerated
merchandiser including an improved air curtain system that consumes
less energy overall. It is a further object of the present invention
to provide a refrigerated merchandiser including a air curtain system
wherein the velocity of the air curtain is varied between a relatively
lower velocity maintained during steady-state operation and a relatively
higher velocity in response to a sensed disturbance in the air curtain
or sensed motion in front of the display case.
The refrigerated merchandiser of the present invention includes
a display case defining a product display region having an open-front
isolated from the ambient air of the store by means of at least
one generally downwardly directed air curtain of relatively cold
refrigerated air. In accordance with the present invention, a sensor
is positioned in operative association with the display case to
sense a disturbance in the air curtain or to detect consumer activity
in the store region immediately in front of the product display
case. The sensor provides an output signal to a controller, the
output signal indicating the existence of a disturbance in the integrity
of the air curtain or motion in the monitored region depending upon
which of the aforementioned sensors is installed. The controller
in turn operates to increase the velocity of the air curtain from
a relatively lower velocity maintained during steady-state operation
to a relatively higher velocity.
BRIEF DESCRIPTION OF THE DRAWINGS
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 with reference
to the accompany drawings wherein:
FIG. 1 is a sectional, side elevation profile of an embodiment
of the refrigerated merchandiser of the present invention;
FIG. 2 is a partly sectioned, planar view, taken along line 2--2
of FIG. 1, showing a multi-fan embodiment of the refrigerated display
case of the present invention incorporating variable capacity fans;
and
FIG. 3 is a partly sectioned, planar view, taken along line 2--2
of FIG. 1, showing a multi-fan embodiment of the refrigerated display
case of the present invention incorporating fixed capacity fans.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, the refrigerated merchandiser 10 includes
an outer cabinet 12 and an inner cabinet liner 20 that defines within
its bounds an open-front product display case 30. The outer cabinet
has a base 13, a rear wall 14 extending upwardly from the back of
the base 13, a top wall 15 extending forwardly from the rear wall
and a pair of side walls 16 extending vertically from the base 13
to the top wall 15 and forwardly from the rear wall 14. The inner
cabinet liner 20 has a top panel 28, a back panel 26, a bottom panel
24 and opposed side panels 23 which together bound the open-front
product display case 30. Each of the cabinet base 13, rear wall
14, top wall 15 and side walls 16 is insulated, as in conventional
practice, to thermally isolate the interior of the cabinet 12, including
the product display case 30, from excessive heat transfer therethrough.
Perishable product being merchandized may be displayed on shelves
18 disposed within the product display case 30 and upon the upper
surface of the bottom panel 24. The product display case 30 has
an open front 25 so as to permit consumers to not only view, but
also reach into the product display case 30 to select and remove
items of product (not shown) that they desire to purchase. Product
display case 30 is cooled in a conventional manner to a desired
product temperature, typically to a temperature between -10.degree.
F. to less than about 40.degree. F., depending upon what product
is being merchandised therein and whether the product is frozen
or non-frozen.
The refrigerated merchandiser 10 further includes a refrigeration
compartment 40, typically disposed in the portion of the display
cabinet 12 between the base 13 and the bottom panel 24, as depicted
in FIG. 1, wherein components of the refrigerant system, typically
a tube coil evaporator 50 and a air circulator, such as for example
one or more fans 60, are housed. For example, in one embodiment
of the present invention as illustrated in FIG. 2, three variable
capacity fans 60A are disposed at spaced intervals across the width
of the display case. In another embodiment of the present invention
as illustrated in FIG. 3, five fixed capacity fans 60B and 60C are
disposed at spaced intervals across the width of the display case.
It will be appreciated by those skilled in the art that the number
of fans employed is a matter of choice that will depend upon the
width of the display case, the capacity of the fans and whether
the fans are of a fixed or variable capacity variety. As in conventional
practice, refrigerant passing through the tubes of the evaporator
50 cools air passing over the surface of the evaporator tubes. The
refrigerant is typically supplied from a remote refrigeration unit
located elsewhere within the store. However, it is to be understood
that the present invention may also be employed on stand alone refrigerated
merchandisers that include their own refrigeration unit for providing
the cold refrigerant.
An air circulation duct 32 is formed between the rear wall 14 and
the top wall 15 of the outer cabinet 12 and the back panel 26 and
top panel 28, respectively, of the inner cabinet liner 20. The fans
60 serve to circulate air from air inlet 42 through the compartment
40 so as to traverse evaporator 50, and thence through duct 32 to
an air outlet 34. As noted before, this circulating air has been
cooled to a desired temperature as it traverses the evaporator 50.
From the air outlet 34, the cool refrigeration air is directed via
vanes provided within the air outlet 34 downwardly along a path
across the open front 25 of the product display region back to air
inlet 42. Thus, the refrigerating air is recycled and repeatedly
recirculated through the compartment 40 and duct 32 to converse
energy expended in cooling the refrigeration air. Further, through
the aforedescribed cooling arrangement, a cool air curtain 55 is
formed across the open-front product display case 30 from top to
bottom thereof. To provide further cooling air directly to the product
display case 30, a plurality of openings may be provided in the
back panel 26 through which a portion of cold refrigerating air
circulating through duct 32 may pass directly into the product display
case 30. Refrigerating air will also be drawn by the fans 60 back
through the air inlet 42 into the compartment 40 to be recirculated.
In accordance with the present invention, at least one sensor 70
is disposed in operative association with the product display case
30. The at least one sensor may comprise a sensor 70A for detecting
a disturbance in the curtain of airflow and/or a motion sensor 70B
for detecting movement in front of the open-front display case 30.
As noted previously, such a disturbance may be caused by a customer
reaching into the product display case 30 to select a product for
purchase or even by a customer walking by or otherwise moving in
front of the open-front product display case 30. The sensor 70 communicates
with a controller 80 operative to control at least one fan 60 to
increase airflow in the air curtain 55 in response to a signal from
the sensor indicating detection of a disturbance in the air curtain
or movement in front of the display case 30. By increasing the airflow
forming the cold air curtain passing across the open-front of the
product display case 30 in response to a disturbance in the air
curtain or movement in front of the product display case 30, a stable
air curtain is reestablished more quickly, resulting in lower infiltration
of warm, moist air from the store into the product display case,
thereby lowering overall energy consumption.
In the embodiment of the present invention depicted in FIG. 2,
at least one of the fans 60A, and most advantageously each of the
fans 60A, is of variable capacity, having at least a first relatively
lower capacity and at least a second relatively higher capacity.
Each of the variable capacity fans 60A is in communication with
the controller 80 and, in response to a signal from the controller
80, will switch from operating at its first relatively lower capacity
to operating at its second relatively higher capacity. The controller
80 will send such a capacity increase signal to each variable speed
fan 60A whenever the controller 80 receives a signal from the sensor
70 indicating detection of a disturbance in the air curtain or movement
in front of the display case 30. Once the disturbance or movement
is no longer present, the sensor 70 will cease signaling the controller
80. In response, the controller 80 will signal each variable capacity
fan 60A to return to its first relatively lower capacity for continued
steady-state operation.
Each variable capacity fan 60A may advantageously comprise an adjustable
speed fan wherein a variable speed motor associated with the fan
responds to the controller 80 to increase the speed at which the
fan blades rotate, thereby increasing the rate of airflow passing
through the fan. Alternatively, each variable capacity fan 60A may
be a constant speed fan having variable pitch blades wherein the
pitch, i.e. angle, of the fan blades changes in response to the
controller 80 to increase the airflow passing through the fan. It
is to be understood that one of ordinary skill in the art may envision
other techniques for adjusting the capacity of a fan to control
the amount of airflow forming the air curtain without departing
from the spirit and scope of the present invention.
In the embodiment of the present invention depicted in FIG. 3,
the fans 60B and 60C are fixed capacity fans. Fans 60B are the primary
air circulating fans for establishing the air curtain 55 and fans
60C are secondary air circulating fans that operate only when called
upon by controller 80 to increase the airflow forming the air curtain
55. Each of the secondary fans 60C is in communication with the
controller 80 and, in response to a signal from the controller 80,
will activate to cause additional airflow to the air curtain 55.
The controller 80 will send such a capacity increase signal to each
fan 60C whenever the controller 80 receives a signal from the sensor
70 indicating detection of a disturbance in the air curtain or movement
in front of the display case 30. Once the disturbance or movement
is no longer present, the sensor 70 will cease signaling the controller
80. In response, the controller 80 will signal each secondary fan
60A to deactivate, thereby returning the air curtain airflow to
the lower rate generated by the steady-state operation of the primary
fans 60B.
The aforementioned description is meant to be exemplary rather
than limiting. Many modifications and variations of the present
invention as described may be recognized by those skilled in the
art in light of the above teachings that will fall within the spirit
and scope of the present invention. The preferred embodiments of
this invention have been disclosed. Accordingly, 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. |