Abstract:
A cover for a cooling unit, such as an evaporator assembly, of a display refrigerator. The cover is advantageously made of a single piece of material, preferably an injection molded, filled polypropylene plastic, which is capable of withstanding the harsh conditions found in a display refrigerator. The cover is further advantageously configured to enhance the operation of the evaporator assembly, protect the evaporator assembly, insulate the frozen or refrigerated food and drink items from the heat generated by the evaporator assembly, and decrease the time needed to install the cover into or remove the cover from the display refrigerator.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to display refrigerators, and more particularly to display refrigerators having an internal evaporator assembly. 
     2. Related Prior Art 
     Display refrigerators are commonly used in retail outlets such as supermarkets, restaurants, convenience stores and other establishments that sell frozen or refrigerated items. Display refrigerators typically include a case having a plurality of shelves supporting the items on display. Doors, usually made of glass, allow a consumer to survey the selection of items without having to open one or more of the doors. When a selection is made, the consumer opens the appropriate door, removes the desired item and thereafter closes the door. 
     It is known to provide a display refrigerator with an evaporator assembly to keep the interior display space of the refrigerator cold. The evaporator assembly is generally housed beneath the interior display space. It is also known to provide the display refrigerator with a fan that is operable to circulate air contained by the display case through the evaporator assembly. In general, the fan draws air from the interior display space through the evaporator assembly where the air is cooled, and then recirculates the air into the interior display space. In this regard, display refrigerators periodically operate to defrost the refrigerant coils that are part of the evaporator assembly. A consequence of such defrost cycles is that periodically the evaporator warms the air in the lower region of the display case adjacent the evaporator coils. 
     It is also generally known to separate the evaporator assembly with a grill or cover to conceal the evaporator assembly and to protect the components of the evaporator assembly from damage by items falling from the shelving or by spillage. Known covers are often made of multiple pieces which are configured to cooperate in forming an evaporator cover assembly and which extend between the front of the display case and the back of the display case. The individual pieces of the cover assembly are generally made of metal grills and/or sheets to provide strength and to withstand low temperatures, though it is also known to provide a multiple piece cover assembly made of plastic or a combination of metal and plastic. The individual pieces are also configured to expand and contract when exposed to varying temperature conditions in the display refrigerator caused by the alternating operation of the evaporator assembly through cooling and defrost cycles. 
     SUMMARY OF THE INVENTION 
     As can be appreciated, a cover used to conceal an evaporator assembly placed beneath an interior display space must be of sufficient strength to substantially span the distance between the front of a display case to the back of a display case or to the front of the evaporator coil. The cover must also be able to withstand the low operating temperatures of a display refrigerator without cracking. Moreover, during defrost cycles the air in the interior display space above the cover is generally colder than the air directly surrounding the evaporator assembly and below the cover. Thus, the cover must also be able to withstand a temperature differential between its top side and its bottom side without cracking. 
     A problem with metal grills and covers is that manufacturing costs for metal display refrigerator evaporator covers are not viewed as cost effective. Furthermore, metal is generally a poor insulator. As a consequence, the warmth generated by the evaporator assembly or other heat source during defrost cycles is permitted by metal covers to infiltrate the upper regions of the display refrigerator. This heat infiltration is undesirable primarily because of the prospective damage to goods in the display refrigerator. Another substantial disadvantage caused by heat transfer through known cover assemblies is the fact that the defrost cycles must continue for a longer period than optimum, and subsequent cooling cycles must cool not only air warmed in the lower regions of the display refrigerator, but also the air in the upper display. Another problem with grills in general is that particulates, such as dust, dirt and the like, can fall through the grill into the evaporator assembly and, consequently, adversely affect the operation of the evaporator assembly. In addition, grills often expose pipes, wiring, conduits and other utilities serving the evaporator assembly, as well as dirt, dust and other articles that may fall into the lower portion of the display refrigerator. Such exposure is generally unsightly and undesirable in a retail setting. 
     Known plastic evaporator assembly covers present deficiencies in the areas of strength and durability. In general, known plastic cover assemblies are not sufficiently strong to span the distances necessary to cover an evaporator assembly. Also, known plastic covers tend to crack at low temperature. 
     One problem with known multiple piece cover assemblies concerns the amount of time needed to install the pieces into or remove the pieces from a display refrigerator. Multiple piece evaporator assembly covers made of a metal portion and a plastic portion have stress concentrations at the interface of the two different materials because, e.g., of the differences in the expansion and contraction properties of the different materials. These stress concentrations often result in cracking, and generally adversely affect the overall function of the covers and reduce the accepted operating life of the covers. 
     The invention addresses the problems presented by the prior art. In one aspect, the invention provides a cover that can be positioned between a cooling unit of a display refrigerator and an interior display space of the display refrigerator. The cover is advantageously made of a single piece of material which is adapted to expand from the front of the display case to at least the front of the evaporator coil. Preferably, the single piece cover is made of an injection molded plastic material. The single piece cover is sufficiently strong to span the distance between the front and the back of the display case without sagging or bending. The single piece cover can be exposed to varying temperatures, including very low temperatures, without being damaged or cracked. The single piece cover can also withstand temperature gradients on opposite sides of the cover. Additionally, the single piece cover is a better insulator than metal covers, thereby protecting the items stored in the interior space of the display case from the heat generated by the evaporator assembly during defrost cycles. 
     In one embodiment, the invention provides a cover positioned between an evaporator assembly and an interior display space of a display refrigerator. The cover includes a main body portion and a grill portion that affords fluid flow, such as air flow, communication between the evaporator assembly and the interior display space, and wherein the main body portion and the grill portion are formed as a single piece of material. 
     In another embodiment, the invention provides a cover adapted to be housed in a display refrigerator having a display case and an evaporator assembly within the display case. The cover includes an imperforate main body portion overlying the evaporator assembly and a grill portion affording fluid flow communication between the evaporator assembly and the remainder of the display case, wherein the main body portion and the grill portion are formed as a single piece of injection molded plastic material. 
     In another embodiment, the invention provides a display refrigerator including a display case having a front wall and a rear wall defining an interior space, and an evaporator assembly housed within the interior space. The refrigerator also includes a cover positioned adjacent the evaporator assembly and separating the interior space into a display space and an evaporator assembly portion, the cover extending between the front wall and the rear wall. The cover includes an imperforate main body portion and a grill portion affording fluid flow communication between the display space and the evaporator assembly portion. The grill portion includes a first set of spaced apart, substantially vertical parallel walls and a second set of spaced apart, substantially non-vertical parallel walls which interconnect with said first set of walls to form a plurality of openings. The main body portion and the grill like portion are formed as a single piece of filled polypropylene injection molded plastic. The cover also includes a first side defining a first tab having a recessed upper surface and the cover also includes a second side defining a second tab having a recessed underside and being adapted to be engaged by the first side of a second cover to define therebetween a lap joint. 
     In another embodiment, the cover further includes a locating stud that is positioned to properly locate the cover within the display refrigerator. 
     The invention also provides a display refrigerator having a longitudinal length and a cover assembly including multiple covers configured such that portions of adjacent covers are configured to form a lap joint. The covers expand from one side of the display refrigerator to the other. The lap joints provide a simple, yet effective, manner of installing and removing individual covers into and out of a display refrigerator. 
     In yet another preferred embodiment, the cover includes a notch or recess providing clearance for structural members of the display refrigerator that may support, for example, the display case and/or shelving or to provide clearance for electrical wiring, such as for a lighting system, of the display refrigerator. 
     Thus the invention provides a unique and advantageous display refrigerator evaporator cover. 
     The invention also provides a new and improved display refrigerator evaporator cover which is simple to use and relatively inexpensive to make. 
     The invention provides a display refrigerator cover which conceals the evaporator assembly and other pipes and utilities connected to the evaporator assembly. The cover also prevents dust, dirt and other particulates from passing from the upper regions of the display into the lower portion of the display cabinet housing the evaporator assembly. 
     Another feature of the invention is a display refrigerator evaporator cover that reduces the overall time needed to install or remove the cover, and that serves as a product stop preventing items from falling into the evaporator assembly. 
     Still another feature of the invention is a display refrigerator evaporator cover having sufficient strength and made of appropriate material to withstand the environmental conditions of display refrigerators. 
    
    
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view, partially in section, of a display refrigerator embodying the present invention. 
     FIG. 2 is a perspective view of the display refrigerator evaporator cover shown in FIG.  1 . 
     FIG. 3 is view taken along line III—III in FIG.  1 . 
     FIG. 4 is a partial cross-sectional view taken along line IV—IV in FIG.  3 . 
     FIG. 5 is a partial cross-sectional view taken along line V—V in FIG.  3 . 
     FIG. 6 is a perspective view similar to FIG.  2  and shows the underside of the display refrigerator evaporator cover shown in FIG.  2 . 
    
    
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a display refrigerator  10  embodying the present invention. The display refrigerator  10  includes a display case  14  having a front wall  18 , a rear wall  22  and top wall  26  defining there between an interior space  30 . The display refrigerator  10  also includes a plurality of shelves  34  mounted on the rear wall  22  and extending into the interior  30  of the display case  14  for displaying food or drink items. The display refrigerator also includes one or more glass doors  38  which are mounted on the front wall  18  and which allow a consumer to survey the interior  30  of the display case  14  before opening the door  38  by way of handle  42 . 
     The display refrigerator  10  also includes an evaporator assembly  46  which is housed in the lower portion of the display case  14  and which is operable to keep the interior  30  of the display case  14  cold. The evaporator assembly  46  includes cooling coils  50  (shown schematically in FIG. 1 as a bundle of coils and fins) which extend along the length of the display case  14 . For reasons discussed below, the evaporator assembly also includes (FIGS. 1 and 4) a cover mount  54  extending along the lower rear wall  22  into the interior  30  of the display case  14  and having therein one or more location slots or apertures  56 . 
     The evaporator assembly  46  also includes a fan  58  which is mounted on a plenum  62  located adjacent the lower front wall  18  of the display case  14 . During cooling cycles (as represented by arrows in FIG.  1 ), the fan  58  draws air in the interior  30  of the case through the fan plenum  62  and drives the air rearward past the evaporator coils and fins  50  where the air is cooled or, alternatively, heat is removed. In order to defrost the cooling coils and fins  50  of the evaporator assembly  46 , the flow of refrigerant through the evaporator coils is periodically reversed. As is further generally understood, the operation of the evaporator assembly  46  during defrosting cycles generates heat in the region of the coils and fins  50  either through reverse operation of the evaporator assembly or by other means (not shown), such as by electric or hot gas defrost systems. 
     The display refrigerator  10  also includes an evaporator cover  66 . The cover  66  extends between the front wall  18  and the rear wall  22  of the display case  14 , and overlies the evaporator assembly  46 . The cover  66  conceals the evaporator assembly  46  and protects the components of the evaporator assembly  46  from damage such as if, for example, an item falls from a shelf  34 . The cover  66  also separates the interior space  30  of the display case  14  into an upper, display portion  70  and a lower, housing portion  74 . 
     Referring to FIG. 2, the cover  66  is made of a single piece of plastic and preferably is made by injection-molded or thermo-forming. Although various compositions or types of plastic will work according to the principles of the present invention, a filled polypropylene sold by Ferro Corporation under product code LPP40YR01 is particularly well suited for use in fabricating the cover  66  by injection molding. This, and other suitable plastics, has an R factor superior to that of metal and, therefore, has superior insulative properties compared to metal. Thus, the cover  66  also functions as an insulator between the display space  70  where the cold items are stored and the housing portion  74  wherein the evaporator assembly  46  periodically generates heat, thereby protecting the items housed in the display case  14  from being adversely heated. 
     The cover  66  is generally rectangular but may be of different shapes depending on the configuration of the display refrigerator  10 . The cover  66  includes (FIG. 2) a front edge  86 , a rear edge  90 , and opposite sides  94  and  98 . As best shown in FIG. 1, when installed in the display case  14 , the front edge  86  of the cover  66  is adjacent the front wall  18  of the display case  14  and overlies the fan plenum  62 , and the rear edge  90  of the cover  66  is adjacent the rear wall  22  of the display case  14  and overlies the cover mount  54 . As best shown in FIGS. 1 and 6, the underside of the cover  66  has a grid or lattice  102  of spaced-apart, generally straight and parallel elongated structural walls or ribs  106  extending between the opposite sides  94  and  98  of the cover  66  and between the front and rear edges  86  and  90  of the cover  66 . The structural ribs  106  vary in height depending on the location of the ribs  106  between the sides  94 ,  98  and edges  86 ,  90  to accommodate the configurations of the fan plenum  62 , the evaporator assembly  50  and cover mount  54 , while at the same time providing a generally horizontal upper surface. The ribs  102  provide structural strength and stability to the cover  66  to prevent warping and cracking in the cover  66  under loading and thermal stress. 
     More particularly, the cover  66  (FIG. 2) includes a main body portion  110  which is bounded by the rear edge  90  and the opposite sides  94 ,  98  and which extends toward the front edge  86 . The main body portion  110  is imperforate and serves an air flow management function by preventing air flow between the display portion  70  of the case  14  and the evaporator housing  74 . The main body portion  110  of the cover  66  provides a planar upper surface  114  and (FIG. 6) an underside  118  including the grid  102  of ribs  106 . In the illustrated embodiment, near the rear edge  90  of the cover  66 , the ribs  102  are relatively shallow, and over the fan plenum  62 , the ribs  106  are deeper. 
     The main body portion  110  also includes (FIGS. 4 and 6) a locating member or stud  122  extending from the underside  118  of the cover  66  adjacent the rear edge  90 . The locating member  122  is received by the aperture  56  in the cover mount  54  so that the cover  66  can be properly and easily located within the display case  14  (see also FIG.  1 ). It should be noted that the locating stud  122  could be alternatively positioned elsewhere on the cover  66  so as to mate with an appropriately positioned aperture or the like in the display case  14 . Alternatively, the cover  66  could include an aperture or the like similar to aperture  56 , and the display case  14  could include a locating member similar to locating member  122 . 
     The cover  66  also includes a grill portion  126  adjacent the main body portion  110  and the front edge  86  of the cover  66 . The grill portion  126  also performs air flow management functions by permitting flow of air therethrough. To that end, the grill portion  126  is generally defined by the structural ribs  106  extending from the main body portion  110  toward the front edge  86  and by ribs  106  which extend substantially parallel to the front edge  86  between the sides  94 ,  98 . In the grill portion  126  of the cover  66 , the grid  102  of ribs  106  defines a plurality of openings  130  communicating between the top and bottom surfaces  134 ,  138  (FIG. 6) of the cover  66 , which are respectively defined by the upper and lower extents of the ribs  106 . The top surface  134  of the grill portion  126  adjacent the main body portion  110  extends upwardly from the top surface  114  and has a profile (FIG. 1) which curves toward the front wall  18  such that the rearward portion of the grill portion  126  is vertically offset from the forward portion of the main body portion  110 . The grill portion  126  also includes a pair of imperforate sections  142  extending toward the front edge  86  of the cover  66  and respectively along the opposite sides  94 ,  98  of the cover  66 . 
     The top surface  134  of the grill portion  126  ramps downwardly from the rearward extent of the grill toward the front edge  86 . This vertical displacement and ramping of the grill portion  126  discourages the placement of items onto the grill portion  126 , which could adversely affect the overall operation of the evaporator assembly  46  by blocking air flow. In this regard and as best shown in FIG. 1, the ribs  106  in the grill portion  126  which extend laterally between the sides  94 ,  98  of the cover  66  lie in a plane which is at an acute angle relative to vertical. The laterally extending ribs  106  are so positioned to enhance the proper flow of air from the interior display space  70  through the cover  66  and into the evaporator assembly housing  74 . Also, the angled orientation of the ribs  106  tends to conceal the evaporator assembly  46  from direct observation from outside the front of the display case  14  and prevents the passage of dust, dirt and other particulates into the housing portion  74  for the evaporator assembly  46 . In addition, the angled orientation of the ribs  106  prevents the observation of dust, dirt and other articles that may have fallen into the lower portion of the display refrigerator  10 . 
     Thus, the cover  66  includes a main body portion  110  and a grill  126  which affords fluid flow communication between the evaporator assembly housing  74  and the interior display space  70 , and provides a cover  66  wherein the main body portion  110  and the grill portion  126  are formed as a single piece of material. 
     With reference to FIG. 2, the cover  66  preferably includes a notch or recess  150  in one of the sides  94 ,  98  in order to provide clearance for vertically extending structural members (not shown) that may be provided in the display case  14  and/or shelving  34 . Although not shown, the cover  66  may also include one or more notches like notch  150  elsewhere in the cover  66  depending on the design of the display case  14 . The cover  66  also preferably includes a notch or recess  154  in the front edge so as to provide clearance for an insulated wire bundle or the like (not shown) provided in the display refrigerator  10  for lighting devices or other electrical devices (not shown) which may be mounted in or on the display case  14 . Preferably, the notch  154  is defined by a gap in the front edge  86  and by rib segments  106 . Alternatively, one or more notches like notch  154  could be positioned elsewhere in the cover  66 , depending on the design of the display case  14 . If utilized, the notches  150  and  154  are preferably molded into the single piece cover  66  by installing inserts (not shown) in the injection molding tooling which correspond to the shape and size of the notches. Thus, the cover  66  provides a single piece that extends between the front and rear walls  18 ,  22  of the display case  14 . 
     Those of ordinary skill in the art will readily recognize that a display refrigerator  10  may have a length such that a single cover  66  can be used to separate the display  70  and evaporator housing  74  along the entire length of the display case  14 . However, in the event the display case  14  is elongated, such as is shown in FIG. 3, then the invention also provides a cover assembly  170  comprising multiple covers  66 , which extend from one side of the display case  14  to the opposite side. As shown in FIG. 3, the sides  94 ,  98  of each cover  66  are configured so as to cooperate and form a lap joint  174  with adjoining covers  66 . As best shown in FIGS. 2 and 5, the opposite sides  94 ,  98  of the cover  66  have respective configurations that mate when overlapped. More particularly, one side  94  of the cover  66  includes a tab portion  178  that extends from the underside  118  of the cover  66  and that defines a recess  182  from the upper surface  114 . Conversely, the opposite side  98  of the cover  66  includes a tab  186  which extends from the top surface  114  and which is configured to overlap the tab  178  and occupy the recess  182  so that the top surfaces  114  of the adjoining covers  66  are flush. The edges  94 ,  98  are thus configured and adapted to mate to form the lap joint  174  when assembled. 
     FIG. 1 also illustrates that the display refrigerator  10  can be provided with a bottom shelf  200  supported by the rear wall  22  in a position overlying the cover  66  or cover assembly  170 . The bottom shelf  200  is configured to extend over the main body portion  110  without covering any part of the grill portion  126 . The shelf  200  includes a vertical edge  202  adjacent the interface of the main body portion  110  and the grill portion  126 , and is intended to discourage items placed on the shelf  200  from sliding onto the grill  126 . 
     Variations and modifications of the foregoing are within the scope of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
     Various features of the invention are set forth in the following claims.