Supports: cabinet structure – Spaced insulated wall – Refrigerator cabinet
Reexamination Certificate
2001-08-06
2003-12-02
Hansen, James O. (Department: 3637)
Supports: cabinet structure
Spaced insulated wall
Refrigerator cabinet
C049S478100
Reexamination Certificate
active
06655766
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This Application claims priority from British Patent Application No. 0019596.6 filed on Aug. 9, 2000.
FIELD OF THE INVENTION
The present invention relates to refrigeration cabinets, and in particular to a thermal break for use in such refrigeration cabinets, and to an improved method of assembling refrigeration cabinets including such a thermal break.
BACKGROUND OF THE INVENTION
Many refrigeration cabinets, which term includes refrigerators and freezers, especially for industrial and commercial use, cooled display cabinets, morgue cabinets and the like are usually formed of metal, more typically stainless steel, for hygienic purposes, especially ease of cleaning. Typically, such cabinets include an inner stainless steel liner and an outer stainless steel carcass or shell, with the void between the liner and shell being filled with an insulating foam material to provide the desired thermal insulation. As the inside surface of the refrigeration cabinet is at a desired low temperature, and the outside surface will be at an ambient temperature, which in the case of a commercial kitchen will typically be relatively high, for example up to 40° C., there will be thermal tracking between the inside and outside metallic surfaces of the cabinet. This reduces the efficiency of the refrigeration cabinet, since additional cooling will be required to overcome the losses due to thermal tracking. Further, the thermal tracking may lead to the formation of condensation around the door seal. This, in turn, may result in a pool of condensate on the floor. This is undesirable.
A further problem is that the majority of commercial door seals are magnetic. In particular, the door includes a rubber or plastic gasket within that is provided a magnetic strip. This is attracted to the metallic frame of the refrigeration cabinet to keep the door closed. In general, the inner and outer surfaces of the refrigeration cabinets are formed from stainless steel that has a high corrosion resistance, and is therefore a good material for forming the shell and exterior of the cabinet, as this is easy to clean and has a long life. However, such grades of stainless steel may not be magnetic. Therefore, a section of stainless steel having a higher iron content that is magnetic is used to form a door surround that will attract the magnetic strip in the door seal. However, this different grade strip is more susceptible to corrosion.
In an attempt to overcome the problems associated with thermal tracking, it is known to form a thermal break between the inside stainless steel lining of the cabinet and the outer shell using a rubber or plastic strip or break that is positioned between the liner and outer shell. However, this has not proved entirely successful as part of the outer shell, on the outside of the thermal break, will be within the cold interior of the refrigerator cabinet, and therefore thermal tracking and the associated problems will still occur. It has also been proposed to form a thermal break using a hollow plastic member. However, with such an arrangement, it is difficult to form a seal with the door gasket, and the strip has a poor appearance.
Due in part to this thermal tracking, the metallic strip that attracts the magnetic strip in the door gasket will become very cold, and, especially in freezers and other very low temperature cabinets, there is the risk that the strip will become sufficiently cold that the gasket will freeze onto the strip, therefore preventing the door from being opened without damaging the gasket. To overcome this problem, it is known to provide a heater wire behind the region of the door frame on which the door gasket seals. This heater must be positioned before the void between the inner liner and the outer shell of the cabinet is filled with foam. In some cases, especially when the void is filled with foam, damage to the heater wire occurs. In this case, the door frame cannot be heated. In an attempt to overcome this problem, it is known to mount two heaters, side-by-side, behind the door frame. In this way, in the event that one of the heaters fails, either during manufacture or in use, the other heater may be used. Clearly, the requirement to provide two heaters is undesirable due to the additional manufacturing cost. Even where two heaters are provided, in some cases, especially during the use of the refrigeration cabinet, both heaters may fail. In this case, it is not possible to replace the heaters due to the insulation between the inner liner and the outer shell of the cabinet which prevents access, and therefore it is necessary to add an additional frame on the front of the cabinet that includes a new heater element. This is undesirable as it does not have an attractive appearance.
A problem with refrigeration cabinets including a known thermal break as described above is their assembly. In particular, it is difficult to correctly position the liner within the shell, and in general requires the liner to be pulled into the cabinet from the rear while the cabinet is horizontal. This may mean that a person assembling the cabinet has to crawl under the upturned cabinet, and then pull on the liner to get this into the required position. This is likely to cause injury to the assembler, and this in turn can be very expensive to the manufacturer.
A further issue in the manufacture of refrigeration cabinets is the sub-division of the cabinet. In some cases, a cabinet will require a single door for the entire opening of the cabinet. In other cases, the cabinet will require sub-division, using cross-members, to allow multiple doors or drawers giving access to different internal parts of the cabinet. The problems of thermal tracking and the need for and provision of heating elements that apply to the outer frame of the cabinet apply also to each of these partitioning members. Further, it is necessary to determine, when the cabinet is initially being made, which partitions will be required since the cross-members and heaters must be formed and foam filled with the remainder of the cabinet.
BRIEF SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a refrigerator cabinet including an inner liner defining an interior of the cabinet and an outer shell is provided with a hollow member having low thermal conductivity connected between the inner liner and the outer shell around an opening of the cabinet, the hollow member including a strip of magnetic material against which a closure of the cabinet abuts, and a removable cover permitting access to the interior of the hollow member.
With the cabinet according to the present invention, an effective thermal break is provided between the inner liner and the outer shell of the cabinet. In particular, the hollow member between the inner liner and outer shell has low thermal conductivity, and therefore there is little thermal conduction or tracking across the member. Further, as the member includes the surface against which the closure of the cabinet, which may be a door or the front face of a drawer for example, no part of the outer shell is inboard of the thermal break on the cooled interior of the cabinet. Therefore, there is no bridging of the thermal break, as is the case in the prior art.
A further advantage of the arrangement of the present invention is that a heater element may be provided within the thermal break itself, namely within the hollow member. Preferably, the heater element may be provided behind the strip of magnetic material so this can directly heat the surface against which the closure abuts, and thereby prevent the freezing of the closure on the surface. The ability to provide a heater element within the hollow member of the thermal break, in particular by removal of the cover to gain access to the hollow interior of the thermal break and to add or remove a heater element at this time has considerable advantages. In particular, it becomes possible to manufacture all basic cabinets without a heater element. Then, after assembly of the basic unit, a decision ca
Foster Refrigerator (UK) Limited
Hansen James O.
Thompson Hine LLP
LandOfFree
Refrigeration cabinet does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Refrigeration cabinet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Refrigeration cabinet will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3146865