Abstract:
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.

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° F. to less than about 40° 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  60 A 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  60 B and  60 C 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  70 A for detecting a disturbance in the curtain of airflow and/or a motion sensor  70 B 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  60 A, and most advantageously each of the fans  60 A, 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  60 A 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  60 A 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  60 A to return to its first relatively lower capacity for continued steady-state operation. 
     Each variable capacity fan  60 A 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  60 A 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  60 B and  60 C are fixed capacity fans. Fans  60 B are the primary air circulating fans for establishing the air curtain  55  and fans  60 C 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  60 C 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  60 C 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  60 A to deactivate, thereby returning the air curtain airflow to the lower rate generated by the steady-state operation of the primary fans  60 B. 
     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.