Refrigeration – Display type – With air controlling or directing means
Reexamination Certificate
2000-08-17
2001-06-05
Tapolcai, William E. (Department: 3744)
Refrigeration
Display type
With air controlling or directing means
C062S256000, C454S193000
Reexamination Certificate
active
06240739
ABSTRACT:
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 affordin
Ali Mohammad M
Michael & Best & Friedrich LLP
Tapolcai William E.
Zero Zone, Inc.
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