WO2007010267A2

WO2007010267A2 - Improvements in or relating to cold storage

Info

Publication number: WO2007010267A2
Application number: PCT/GB2006/002718
Authority: WO
Inventors: Ian David Wood; Xorge Castro Pelayo; Alexandra Eve Shelton; Edward C. Hammond
Original assignee: Applied Design & Engineering Ltd
Priority date: 2005-07-20
Filing date: 2006-07-20
Publication date: 2007-01-25
Also published as: WO2007010267A3

Abstract

A cold-storage appliance includes at least one insulating container (12,14) being movable with respect to a supporting structure for opening and closing and comprising a plurality of walls each defining a respective external surface portion; and a cooling means (34) adapted to cool the interior of the closed container. When the container is moved to a closed position, a seal (36,42) extending around an external surface portion of the container seals that external surface portion against exposure to air moving over the exterior of the container. This helps to control condensation and icing. The appliance may have first and second insulating containers (12,14) being movable with respect to a supporting structure for opening and closing; and a shared cooling means (34) that supplies cold air via the first container (12) to the second container (14) . This enables a single cooling means to cool both containers (12,14) .

Description

IMPROVEMENTS IN OR RELATING TO COLD STORAGE

This invention relates to cold storage using refrigeration systems, including appliances such as refrigerators and freezers for storing foodstuffs and other perishables.

The invention develops concepts described in prior-published patent applications filed by the Applicant. Those earlier patent applications are exemplified by WO 01/20237, WO 02/073104, WO 02/073105, WO 02/073107, WO 2005/024315 and WO 2006/021819. Their content is incorporated herein by reference.

As in the Applicant's earlier patent applications, the invention involves compartmentalised cold storage appliances for storing items in a cooled environment. The invention extends beyond fixed household devices into industrial, scientific and mobile applications. However, this specification will particularly describe household or commercial cold-storage appliances for storing foodstuffs.

The appliances disclosed in the Applicant's earlier patent applications have containers, usually in the form of drawers, that are sealed from one another to minimise cross-contamination, waste of energy and icing. To this end, each drawer has a lid that seals to and closes the open top of the drawer when the drawer is closed. The interior, but not the exterior, of each drawer is cooled, for example by an evaporator or other cooling means associated with the lid.

Optionally, there is provision to select different temperatures in different compartments to suit different foodstuffs or other contents, and to suit different cold- storage regimes such as refrigeration marginally above zero Celsius and freezing significantly below zero Celsius. Indeed, it is possible for a given compartment to be converted readily from refrigerator to freezer and back again, thereby to vary the proportion of refrigerator space to freezer space in the appliance as a whole. In this way, the appliance can respond to changing cold-storage needs.

Briefly to recap the introduction of WO 01/020237, the advantages of storing foodstuffs and other perishable items in refrigerated and segregated conditions have long been known: refrigeration retards the degradation of such items and segregation helps to prevent their cross-contamination. Accordingly, modern cold-storage appliances such as refrigerators and freezers are usually compartmentalised, albeit not often effectively, so that a user can store different types of food in different compartments. All such appliances have the additional aim of maximising their energy efficiency.

This invention and the inventions in the Applicant's earlier patent applications were devised against a background of typical cold-storage appliances, most of which comprise one or more upright cabinets each with a vertically-sealed hinged door on its front. Substantially all of the interior of the cabinet defines a storage volume, most commonly partitioned by shelves or drawers for supporting stored foodstuffs. Access to all of the shelves or drawers in the cabinet is gained by opening the door.

A cooler unit generates a convection loop within the cabinet, in which air cooled by the cooler unit sinks toward the bottom of the cabinet and as that air absorbs heat during its downward journey, it warms and rises back up to the cooler unit where it is cooled again. It is also possible to have forced-air circulation by means of a fan within or communicating with the cabinet. The shelves or drawers are typically made of wire so that they offer little resistance to this circulation of air.

This invention and the Applicant's earlier patent applications address a major problem with upright refrigerators and freezers, namely the upright door which, when opened, allows cold air to flow freely out of the cabinet to be replaced by warm ambient air flowing in at the top. That rush of ambient air into the cabinet causes its internal temperature to rise, hence consuming more energy in redressing that rise by running the cooler unit. The incoming ambient air introduces the possibility of airborne contamination, and moisture in that air also gives rise to condensation and possibly ice within the cabinet. The more often and frequently the cabinet is opened, as may happen especially in commercial cold storage appliances, the worse these problems get.

In upright-door arrangements, the limitations of the vertical seal mean that loss of cold air and induction of warm air can even occur when the door is closed. Being denser than warmer air, the coldest air collects at the bottom of the cabinet and applies pressure to the sealing interface so that unless the seal forms a perfect seal between the door and the cabinet, that air will escape. This invention and the Applicant's earlier patent applications also address the problems inherent in the well-known chest freezer, whose open-topped cabinet is typically closed by a horizontally-hinged upwardly-opening lid. Such a chest freezer is inconvenient and wasteful of space because it precludes use of the space immediately above the freezer, which space must be preserved to allow its lid to be opened. Even if a sliding lid is used instead of an upwardly-opening lid, items cannot be left conveniently on top of the lid. It is also well known that large chest freezers can make access to their contents extremely difficult, it being necessary to stoop down and shift numerous heavy and painfully cold items to get to items at the bottom of the freezer compartment.

Finally, this invention and the Applicant's earlier patent applications address the problem of segregating different types of foodstuff or other perishable items to avoid cross-contamination. In typical cold-storage appliances, segregation of food is compromised by the convection and/or forced-air principles on which those appliances rely. The substantially open baskets or shelves designed to promote convective circulation of air between the compartments also promote the circulation of moisture, enzymes and harmful bacteria. In addition, any liquid that may spill or leak, such as juices running from uncooked meats, will not be contained by the open baskets or shelves. The sealed containers of the Applicant's earlier patent applications avoid this.

In the Applicant's earlier patent applications, containers in the form of insulated drawers are stacked one above another with their associated insulated lids. The lids and drawers alternate in the stack. Drawers and their lids may also, or alternatively, be disposed side-by-side. Each lid has its own cooling means which is adapted to cool the interior but not the exterior of the associated drawer. Indeed, means may be provided to promote a flow of ambient or heated air within the unit and around the closed drawers as proposed in the Applicant's earlier patent applications WO 01/20237 and WO 02/073105.

Whilst each drawer of the Applicant's earlier patent applications is open-topped for access to its contents when pulled clear of the lid that normally closes the open top, each drawer also has an insulated floor in addition to insulated upright walls. When drawers and lids are insulated to the extent that they can be exposed to ambient or above-ambient external temperatures without excessive heat gain, the lids and the floors and upright walls of the drawers must be of appreciable thickness.

Moreover, the Applicant's earlier patent applications such as WO 01/20237 and WO 02/073105 contemplate substantial air gaps between adjacent drawers and between drawers and adjacent lids of other drawers. The purpose of those air gaps is not merely to promote air flow but more particularly to ensure a beneficially steep temperature incline across the insulation thickness of each drawer and lid. Otherwise the exterior of a drawer or lid may cool below dew point or even below freezing point, giving rise to condensation and possibly icing. This is a particular risk when the insulation of a drawer or lid is very close to, or touches, the insulation of an adjacent drawer or lid. In that case, over time, a shallow temperature incline develops across the combined thicknesses of insulation leading from one cooled volume to another. This presents a risk of condensation at the interface between the layers of insulation, whenever that interface is exposed to warm moist air open opening a drawer. Indeed, if the temperature in at least one of the cooled volumes is low enough, the interface temperature may drop below freezing point whereupon any condensation will lead to ice formation at the interface.

Where a cold-storage appliance contains multiple containers and lids, multiple layers of insulation and multiple intermediate air gaps will impact negatively upon the cooled storage space available within the appliance. It is desirable to minimise the internal volume of the appliance that is devoted to insulation and air gaps and hence to maximise the internal volume that is available for cold storage, but without risking excessive heat gain to the cooled volume and hence excessive energy consumption. It is also desirable to minimise the number of cooling means in the appliance, to the benefit of both space utilisation and cost.

The present invention resides in the idea of peripheral sealing around at least one external surface portion of a refrigerated storage container in a cold-storage appliance. The purpose of sealing is to create a vapour barrier around that surface portion of the container. This isolates the sealed surface portion from air flows around the container which may be moisture-laden and contaminated and so could otherwise give rise to icing and deposition of contaminants such as bacteria on that surface portion. In doing so, the seal allows the sealed surface portion to be exposed to colder (preferably below-ambient) air than would otherwise be acceptable due to the risk of condensation or icing, hence reducing heat gain into the container via that surface. Indeed, where there is little or no insulation behind the sealed surface portion, that surface portion may be at nearly the same low temperature as the contents of the container.

As layers of insulation and intermediate air gaps are eliminated or reduced, the appliance can provide more cold storage space for a given external volume.

Where the container is a drawer, the seal may be a magnetic sliding seal extending in a loop around the bottom of the drawer, to seal against the insulated lid or the open top of a drawer below. It is possible for the seal to be carried by the upper drawer and to seal against the lid or the lower drawer or for the seal to be carried by the lid or the lower drawer and to seal against the upper drawer. However if there is no drawer and hence no lid below, it would instead be possible to seal against an insulated base panel of the appliance.

It is not essential, though much preferred, that sealing is effected around the base of the drawer. It would also, or alternatively, be possible to seal around the side and/or back surfaces of the drawer. For example, side-by-side drawers may be apt for sealing around their adjoining side surfaces.

In a broad sense, and from one aspect, the invention resides in a cold-storage appliance including: at least one insulating container being movable with respect to a supporting structure for opening and closing and comprising a plurality of walls each defining a respective external surface portion; and a cooling means adapted to cool the interior of the closed container; wherein when the container is moved to a closed position, a seal extending around an external surface portion of the container seals that external surface portion against exposure to air moving over the exterior of the container. That air may be ambient or heated air, whose movement may be driven by an impeller or by convection. The seal may be attached to the container around the associated external surface portion to move with the container. Alternatively, the container may move away from the seal upon opening: for example, the seal may be fixed with respect to the structure.

The container is preferably open-topped to retain cold air when open. In that case, an insulating lid suitably closes the open top when the container is moved to the closed position. That lid may be fixed to the structure and the cooling means may be associated with the lid. Alternatively, when the container is moved to the closed position, a wall of another container may close the open top. That other container preferably has insulating walls but the wall that closes the open top may be substantially less insulating than those walls, or indeed non-insulated. The wall that closes the open top may even be penetrated by one or more apertures.

In general, an external surface portion of the or each container may be sealed to an adjacent container of the appliance, to a lid of an adjacent container of the appliance, to an opposed cabinet wall of the appliance, or to a wall beside the appliance. Suitably, the adjacent container or lid, or the opposed cabinet wall, or the wall beside the appliance, is insulated at least in the region opposed to that external surface portion.

The or each container may be generally cuboidal, such that the sealed external surface portion is substantially planar. For example the walls of a container may comprise a floor and a plurality of upright walls upstanding from the floor that together define an open top. Those upright walls may include side walls and a rear wall. The side walls may be mutually parallel and lie in planes parallel to the direction of opening and closing movement of the container.

An external surface portion defined by the floor of an upper container may be sealed to an opposed Hd of a lower container of the appliance. Alternatively, such an external surface portion may be sealed around the open top of a lower container of the appliance. The floor may then be penetrated by at least one aperture permitting air to flow between the upper and lower containers. To avoid loss of cold air, a valve means responsive to the opening of either container may be operable to close the or each aperture of the floor.

More generally, the appliance of the invention may have first and second containers whose cooled storage volumes are in mutual communication when closed. Cold air may be conveyed in use from the cooling means to one container via the other container.

Means may be provided to handle such condensation as may arise at the sealed external surface portion. For example, there may be a condensation removal duct communicating with the sealed external surface portion. That duct may extend from the sealed external surface portion into the interior of the container, and may be closable by a valve that opens when the container is closed. The valve closes when the container is open to prevent loss of cold air from the container through the duct. Another option is trace heating means operable to warm the sealed external surface portion. The trace heating means may operate continuously or intermittently, for example only when a container is open.

Where the appliance has first and second containers, one of said containers may be configured as a refrigerator and the other of said containers may be configured as a freezer. To keep the interface temperature about freezing point, there may be greater insulation between the sealed external surface portion and a cooled storage volume of the freezer container than between the sealed external surface portion and a cooled storage volume of the refrigerator container.

To ease opening, the container may taper away from its opening direction. For example, the container may have upper and lower interface surfaces, either or both of which are inclined relative to the horizontal.

The container may be supported by horizontally-extending runners whereby the container can be moved for opening and closing and supported when closed or open. For example, the container may be a drawer that translates between closed and open positions. It is also possible for a container to be a drawer that moves between closed and open positions by swinging relative to the lid about a substantially vertical pivot axis, or a drum that moves between closed and open positions by swinging relative to the lid about a substantially horizontal pivot axis.

From another aspect, the invention resides in a cold-storage appliance including: first and second insulating containers being movable with respect to a supporting structure for opening and closing; and a shared cooling means for cooling the interiors of the first and second containers; wherein, in use, cold air is supplied from the cooling means via the first container to the second container. This enables a single cooling means to cool both containers. Nevertheless, the first container may be configured as a refrigerator and the second container may be configured as a freezer.

A wall of the first container suitably includes at least one duct or aperture that, when the first container is closed, communicates with the cooling means and with the interior of the second container to convey cold air from the cooling means to the second container. Cold air may, for example, pass through a cooled storage volume of the first container to a cooled storage volume of the second container.

Cold air may pass through a wall of the first container en route to the second container. That wall of the first container may partition the cooled storage volume of the first container from the cooled storage volume of the second container. Another arrangement has at least one duct in that wall of the first container, the duct being separated from the cooled storage volume of the first container. The duct suitably extends transversely with respect to the thickness of the wall, for example supplying cold air downwardly through an upright wall from the cooling means into an open top of the second container. To this end, the duct may extend from a first plenum chamber around the cooling means to a second plenum chamber communicating with the second container. Where the second container has an open top closed by the first container, the second plenum chamber is suitably disposed in the underside of the first container. The second plenum chamber may be partially defined by a diffuser.

For the purpose of heat conduction, the duct may be positioned substantially closer to the cooled storage volume of the first container than to the exterior of that container. Thus, there may be substantially more insulation disposed between the duct and the exterior of the container than is disposed between the duct and the cooled storage volume of the container.

There may be more than one duct, for example at least one air supply duct leading from the cooling means to the second container and at least one air return duct leading to the cooling means from the second container. To avoid loss of cold air from the duct when a container is open, a sensor may detect when either container is open. A valve responsive to the sensor may block cold air flow through the duct in that event.

The first container may be cooled by conduction of heat into cold air emanating from the cooling means. Conduction may be through at least one internal surface of the first container, that heat then being transferred to cold air flowing from the cooling means to the second container. Conduction may also, or alternatively, be through a wall of the first container adjoining the second container, that heat then being transferred to cold air supplied by the cooling means to the second container. Conduction may also, or alternatively, be through a partition between the cooling means and a cooled storage volume of the first container, that heat then being transferred to cold air emanating from the cooling means. That partition may be impermeable such that air emanating from the cooling means is segregated from air inside the first container, or may be permeable such that air emanating from the cooling means can be bled into the first container.

Again, at least one of the containers may be open-topped and an insulating lid fixed to the structure may close the open top when that container is moved to the closed position. The cooling means is suitably associated with the lid. The second open- topped container may be closed by a wall of the first container when the second container is moved to the closed position, that wall suitably being sealed around the open top of a second container.

Seals used in the appliance of the invention may be magnetic seals suitable for creating a vapour seal. They may be sliding seals.

In order that the invention can be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: Figure l(a) is a front elevation view of a two-drawer refrigerator/freezer unit;

Figure l(b) is a cutaway side view of the unit of Figure l(a) with the drawers closed;

Figure l(c) corresponds to Figure l(b) but shows the drawers open;

Figure l(d) is a top plan view of the upper drawer of the unit of Figure l(a);

Figure l(e) is a top plan view of the lower drawer of the unit of Figure l(a);

Figure 2 is a sectional front view of the unit of Figure 1 showing one possible internal arrangement of the unit having a fully insulated upper drawer;

Figure 3 corresponds to Figure 2 but shows another possible internal arrangement of the unit of Figure 1 having less insulation in its upper drawer by virtue of a lid of a lower drawer insulating the underside of the upper drawer;

Figure 4 is a sectional side view of an embodiment of the invention similar to that of Figure 3;

Figure 5(a) is a cutaway side view of a variant of the unit of Figure 1, in which seals are inclined with respect to the opening direction of the drawers;

Figure 5(b) corresponds to Figure 5(a) but shows the drawers open;

Figure 6 is a sectional side view of an embodiment of the invention in which air flows between an upper drawer and a lower drawer;

Figure 7 is a sectional side view of an embodiment of the invention in which air is channelled through and around an upper drawer into a lower drawer; and Figure 8 is a perspective view of the upper drawer of the embodiment of Figure 7.

Referring firstly to Figures l(a) to l(e) of the drawings, a two-drawer refrigerator/freezer unit 10 comprises an upper drawer 12 and a lower drawer 14. The drawers 12, 14 are disposed under a worktop 16 that may be part of the unit 10, if free-standing, or part of a structure into which the unit 10 is built. The unit 10 further includes a cabinet 18 as best seen in the side views of Figures l(b) and l(c) although a cabinet 18 may not be necessary in a built-in installation where the unit 10 is surrounded by walls and/or other units. In that case, some other supporting structure such as a frame may support the drawers 12, 14. Side walls of the cabinet 10, or other supporting structure, support horizontally-extensible telescopic runners 20 whereby the drawers 12, 14 can be withdrawn from under the worktop 16 and supported when open.

A control panel 22 is offset to one side at the front of the unit 10, being set into the front of the upper drawer 12 near the worktop 16. This is a convenient height for operation and viewing.

A condenser 24 in a void under the lower drawer 14 exhausts heat through a grille 26 at the bottom front of the unit 10. The grille 26 may also be used to promote the flow of ambient or heated air within the unit 10 and around the closed drawers 12, 14 as proposed in the Applicant's earlier patent applications WO 01/20237 and WO 02/073105.

The unit 10 shown in Figures l(a) to l(e) may be used for household refrigeration or for food service or other commercial applications. The upper drawer 12 is normally set as a refrigerator and the lower drawer 14 is normally set as a freezer but those attributes may be reversed or varied if required. For example WO 01/20237 explains how each drawer of a multi-drawer unit may be reconfigured for refrigeration or for freezing so that the proportion of freezer space to refrigerator space within the unit can be varied at will. It is also possible for one or more of the drawers 12, 14 to have other functions, such as blast-chilling or thawing. Figures l(d) and l(e) show that the internal section of each drawer 12, 14 is generally oblong in plan save for an indentation 28 in a rear bottom corner of the lower drawer 14 shown in Figure l(e) that projects into the interior of that drawer 14. That indentation provides clearance for a compressor 30 that projects up behind the condenser 24 under the lower drawer 14 as best shown in Figures 2 and 3. Figures l(d) and l(e) also show how the upright walls of the drawers 12, 14 are insulated, the insulation of the lower drawer 14 being thicker than that of the upper drawer 12 to reflect its freezer function.

The sectional views of Figures 2 and 3 show that like WO 01/20237, each drawer 12, 14 has an insulated lid 32 having cooling means 34 such as an evaporator that cools the interior but not the exterior of the closed drawer 12, 14 beneath. A seal 36, preferably magnetic, around the open top of each drawer 12, 14 seals the drawer 12, 14 to its associated lid 32 when the drawer 12, 14 is closed. Also like WO 01/20237, ambient air bathes the insulated sides of the drawers 12, 14, and the insulated underside of the lower drawer 14, to minimise icing and condensation by keeping their external surface temperature above the dew point. Indeed, the exterior sides of the drawers 12, 14 and the underside of the lower drawer can even be heated as proposed in WO 02/073105. The drawer runners 20 also benefit from being exposed to ambient or heated air and so are not at risk of icing or corrosion caused by condensation.

Figure 3 differs from Figure 2 in that the upper drawer 12 of Figure 2 has an insulated base 38 whereas the upper drawer 12 of Figure 3 does not. In both cases, there is a small air gap 40 between the underside of the upper drawer 12 and the lid 32 of the lower drawer 14. The external heat gain to the interior of each drawer 12, 14 will be at the maximum if the air gap 40 is exposed to free ambient airflow or to heated airflow. However, the heat gain may be reduced by allowing the temperature in the air gap 40 to fall below ambient. Temperature reduction can be achieved by reducing or preventing ambient airflow in the air gap 40. The reduced temperature in the air gap 40 is ideally reduced to just above the dew point of the ambient air to prevent the formation of condensation, although measures can be taken to deal with condensation as will be explained. The arrangements of Figures 2 and 3 prevent ambient airflow through the air gap 40 between the underside of the upper drawer 12 and the Hd 32 of the lower drawer 14. So, unlike WO 01/20237 and WO 02/073105, a substantial external portion of the upper drawer 12 - its underside in this instance - is not exposed to ambient air flow or to heating. To this end, the underside of the upper drawer 12 is sealed around its periphery to the lid 32 of the lower drawer 14. A magnetic seal 42 is preferably used to create a vapour barrier around the perimeter of the drawer/lid interface and hence to prevent the formation of condensation and ice when the upper drawer 12 is closed.

Where a seal 42 is employed at the interface, the insulation at the base 38 of the upper drawer 12 becomes redundant. Figure 3 therefore shows the insulation removed from the base 38 of the upper drawer 12; instead, a thin solid plastics floor 44 supports the contents of the upper drawer 12 and retains cold air within the upper drawer 12 when the drawer 12 is open. The base of the upper drawer 12 now seals directly to the insulated Hd 32 of the lower drawer 14.

By reducing heat gain to the cooled volumes of the drawers 12, 14, the embodiments of the invention shown in both Figures 2 and 3 reduce energy consumption. Figure 3 has the additional benefit of more chilled storage space being available in the upper drawer 12 by virtue of the absence of insulation in the base of that drawer 12. The greater internal depth of the upper drawer 12 of Figure 3 may be contrasted in this respect with the relatively shallow upper drawer 12 of Figure 2.

The seal 42 around the underside of the upper drawer 12 allows the air temperature within the air gap 40 to fall below ambient or even below zero Celsius. Both of the opposed cold horizontal surfaces at the interface (namely the underside of the upper drawer 12 and the upper side of the lid 32) will be exposed to ambient air when the upper drawer 12 is open. There may be consequential condensation and icing on those surfaces, depending upon their temperature relative to the dew point of the ambient air. Nevertheless in the arrangement in Figure 3 where there is insulation between the air gap 40 and the lower drawer 14 serving as a freezer, the temperature at the interface will be close to the storage temperature in the upper drawer 12 serving as a refrigerator (i.e. above zero Celsius). This precludes the formation of ice following drawer opening. Where condensation arises on the cold interface surfaces following drawer opening, this moisture may later be absorbed into the upper drawer 12 by evaporation when the upper drawer 12 is closed again. A permanent airway (not shown) between the air gap 40 and the upper drawer 12 may exist for this purpose or a valved arrangement that opens only when the upper drawer 12 is returned to the closed position, the valve preventing cold air falling out of the drawer 12 when the drawer 12 is open.

Temperatures at the drawer/lid interface can be further controlled by trace heating using heating elements (not shown) mounted just below the top surface of the lid 32.

Such elements may use hot refrigerant bled from the cooling circuits of the unit 10, such as hot gas or liquid line coils. It is also possible to use electric heating elements.

Operation of the heating elements may be dependent upon drawer opening so that heating is applied only when there is a risk of condensation or only when there is a need to evaporate such condensation as may form.

The embodiment shown in Figure 4 is similar to that of Figure 3 but shows the sealing and cooling arrangements in more detail. Like numerals are used for like parts. Again, using the lower lid 32 as insulation allows the use of less, or no, insulation in the floor 44 of the upper drawer 12, to the benefit of space efficiency. In this respect, the deep interior of the upper drawer 12 in Figure 4 may again be contrasted with the shallower interior of the upper drawer 12 of Figure 2.

The upper drawer 12 in Figure 4 has four insulated upright walls 46 but a non- insulated or substantially less-insulated floor 44. The open top of the upper drawer 12 is insulated, when closed, by an upper lid 32. A peripheral seal 36 is at the interface between the upper drawer 12 and the upper lid 32.

An inclined evaporator fan coil 34 set into the upper lid 32 resides within a plenum chamber 48 defined by a recess in the underside of the lid 32 closed by a horizontal partition 50. The plenum chamber 48 communicates with the interior of the upper drawer 12, when the drawer 12 is closed, via apertures 52 in the partition 50. By way of those apertures 52, recirculating convective air flow arises between the plenum chamber 48 and the upper drawer 12 as shown by the arrows in Figure 4. The partition 50 and the apertures 52 diffuse the air flow from the evaporator 34.

The floor 44 of the upper drawer 12 is insulated by a peripheral seal 42 that connects the upper drawer 12 with a lower lid 32. The open top of the lower drawer 14 is insulated, when closed, by the lower lid 32. A seal 36 is at the interface between the lower drawer 14 and the lower lid 32. The lower drawer 14 has normal insulation on its four upright walls 54 and its floor 56. A second evaporator 34 set into the lower lid 32 cools the interior of the lower drawer 14, when closed.

The lower lid 32 therefore provides insulation for both the bottom of the upper drawer 12 and the top of the lower drawer 14. This solution can be repeated as many times as required downwards, when using three or more drawers. In each case, a seal 42 may be carried by a lid 32 or by a drawer 12, 14 to bear against an opposed sealing surface or against an opposed seal.

Figures 5(a) and 5(b) show a biased drawer and lid arrangement, Figure 5(a) showing the upper drawer 12 in the closed position and Figure 5(b) showing the upper drawer 12 in the open position. In this arrangement, the upper drawer 12 tapers rearwardly by virtue of either, or both, of its upper and lower interface surfaces 58, 60 being inclined relative to the horizontal. This tapered, wedge-like arrangement reduces the forces required to open and close the drawer against two magnetic seals, although the arrangement can also be used for only one magnetic seal.

Specifically, the upper interface surface 58 around the open top of the upper drawer 12 inclines downwardly when viewed from the front, i.e. from the right in Figures 5(a) and 5(b). The lower surface 62 of the upper lid 32 is correspondingly inclined to lie parallel to the upper interface surface 58 of the upper drawer 12. A magnetic seal (not shown) around the open top of the upper drawer 12 seals the upper drawer 12 to its associated upper lid 32 when the upper drawer 12 is closed. Similarly, the lower interface surface 60 of the upper drawer 12 facing the lower lid 32 inclines upwardly when viewed from the front. The upper surface 64 of the lower lid 32 is correspondingly inclined to lie parallel to the lower interface surface 60 of the upper drawer 12. A magnetic seal (not shown) between the lower interface surface 60 of the upper drawer 12 and the upper surface 64 of the lower lid 32 seals the upper drawer 12 to the lower lid 32 when the upper drawer 12 is closed, hence closing off the air gap 40 between the upper drawer 12 and the lower lid 32.

It will be noted that like the arrangement shown in Figures 3 and 4, the upper drawer 12 has no insulation in its floor: however, it would be possible to use a fully-insulated upper drawer 12, as shown in Figure 2, in the arrangement of Figures 5(a) and 5(b).

Moving on now to Figure 6, this embodiment also allows less, or no, insulation in the floor 44 of the upper drawer 12 but in this case eliminates the requirement of a lower lid 32. Here, both drawers 12, 14 are connected by a common seal 42 between the bottom of the upper drawer 12 and the open top of the lower drawer 14, and the drawers 12, 14 communicate with each other such that air can flow between the drawers 12, 14.

The upper drawer 12, the upper lid 32 and the lower drawer 14 are similar to those of Figure 4, except that the floor 44 of the upper drawer 12 is penetrated by apertures 66 through which air can flow convectively between the upper drawer 12 and the lower drawer 14, and vice- versa, for distribution of cold air between the drawers 12, 14. The upper drawer 12 therefore has four insulated upright walls 46 but a non-insulated or substantially less-insulated floor 44. Conversely the lower drawer 14 has normal insulation on its four upright walls 54 and its floor 56. When closed, the open top of the upper drawer 12 is insulated by the upper lid 32, and the upper drawer 12 and the upper Hd 32 are sealed to each other by a seal 36 at their peripheral interface. Again, an evaporator 34 in a plenum chamber 48 in the upper lid 32 communicates with the interior of the upper drawer 12, when closed, via apertures 52 in a partition 50 that encloses the evaporator 34.

A peripheral seal 42 connects the bottom of the upper drawer 12 with the top of the lower drawer 14 when the drawers 12, 14 are both closed or when both drawers 12, 14 are open together. As shown by the arrows in Figure 6, recirculating convective air flow arises between the upper and lower drawers 12, 14 via the apertures 66 in the floor 44 of the upper drawer 12. This is additional to the recirculating convective air flow that arises between the plenum chamber 48 and the upper drawer 12 via the apertures 52 in the partition 50 in the upper lid 32. Thus, cold air from the evaporator 34 in the upper lid 32 also cools the interior of the lower drawer 14, hence obviating a second evaporator for the lower drawer 14. It follows that the upper and lower drawers 12, 14 will be at similar temperatures and that both will therefore be configured as freezers or as refrigerators as appropriate, although there may still be provision for variable temperature in the drawers.

When both drawers 12, 14 are open together, the peripheral seal 42 maintains both drawers 12, 14 as a single cooled volume so there will be no downward leakage of cold air from the upper drawer 12. Conversely when one drawer 12, 14 is open while the other is closed - either when the upper drawer 12 is opened when the lower drawer 14 is closed, or when the lower drawer 14 is opened when the upper drawer 1 is closed - there could be downward leakage of cold air from the upper drawer 12 through the apertures 66 in its floor 44. Shutters or other valve means (not shown) responsive to the opening of either drawer 12, 14 may therefore be provided to close those apertures 66, particularly while one drawer 12, 14 is open and the other is closed. It is also possible to link the upper drawer 12 to the lower drawer 14 such that the lower drawer 14 will always open with the upper drawer 12 when the upper drawer 12 is opened, the lower drawer 14 thereby remaining under the upper drawer 12 to retain cold air. The lower drawer 14 may be opened independently of the upper drawer 12 when it is necessary to access the lower drawer 14.

There are other ways to convey cold air into the lower drawer 12 from a cooling means 34 associated with the upper lid 32. One way is to provide a duct outside the cooled storage volume of the upper drawer 12. That duct may be wholly outside the upper drawer 12 or may extend through a wall of the upper drawer 12 as proposed in the embodiment of Figures 7 and 8 of the drawings.

An aim of the embodiment of Figures 7 and 8 is to enable two or more insulated drawers 12, 14 to be cooled by one set of evaporator fan coil components, or other cooling means 34, thereby avoiding the need for additional cooling means for the lower drawer 14. Further, by providing cooling to the lower drawer 14 by means of ducting through a wall of the upper drawer 12, only one seal 42 is required between adjacent drawers. This improves cost and energy efficiency, as well as the ease of opening and closing the drawers 12, 14. The ducting configuration has the additional benefit of a freezer compartment in the lower drawer 14 that is frost-free, if the lower drawer 14 is configured as a freezer.

Like the embodiment of Figure 4, the embodiment of Figure 7 includes an upper drawer 12, an upper lid 32 and a lower drawer 14. Like the embodiment of Figures 5(a) and 5(b), the upper interface surface 58 around the open top of the upper drawer 12 inclines downwardly when viewed from the front, i.e. from the left in Figure 7. The lower surface of the upper lid 32 is correspondingly inclined to lie parallel to the upper interface surface 58 of the upper drawer 12.

A magnetic seal 36 around the open top of the upper drawer 12 seals the upper drawer 12 to the upper lid 32 when the upper drawer 12 is closed. The upper drawer 12 has four thickly-insulated upright walls 46 and a thinly-insulated or non-insulated floor 44, whereas the lower drawer 14 has normal thick insulation on its four upright walls 54 and its base 56. A peripheral seal 42 connects the bottom of the upper drawer 12 with the top of the lower drawer 14 when the drawers 12, 14 are both closed or when both drawers 12, 14 are open together.

As best shown in Figure 8, the insulated upright walls 46 of the upper drawer comprise two side walls 46S, a front wall 46F of similar thickness to the side walls, and a rear wall 46R that is substantially thicker than the side walls 46S or the front wall 46F. The thickness of the rear wall 46R accommodates slots 68, 70 that extend downwardly from the top to the bottom of the upper drawer. Specifically, three planar slots 68, 70 are disposed side-by-side in a common vertical plane: a large central inner slot 68 and two smaller outer side slots 70, one each side of the central slot 68.

The plane of the slots 68, 70 is offset with respect to the thickness of the rear wall 46R, being substantially closer to the rear internal surface 72 of the upper drawer 12 than to the rear external surface 74 defined by the rear wall 46R of the upper drawer 12. So, there is relatively thin insulation between the slots 68, 70 and the rear internal surface 72 of the upper drawer 12; conversely, there is a substantial thickness of insulation between the slots 68, 70 and the rear external surface 74 of the upper drawer 12: the insulation there is at least as thick as the thickness of the side walls 46S and the front wall 46F.

An evaporator fan coil 34 in a plenum chamber 48 in the upper lid 32 communicates with the lower drawer 14 via the slots 68, 70 in the upper drawer 12. Air cooled by the evaporator 34 travels down the central slot 68 which serves as a supply duct, before being conveyed to the lower drawer 14 via a plenum chamber 76 in the underside of the upper drawer 12. That plenum chamber 76 is partially defined by a diffuser plate 78 fixed to the underside of the upper drawer 12. Air flow inside the lower drawer 14 is such that warmed air travels up the side slots 70 which serve as return ducts leading back to the plenum chamber 48 of the evaporator 34. The diffuser plate 78 distributes cold air entering the lower drawer 14 and returns air via the side slots 70 to the upper lid mounted evaporator 34.

The evaporator 34 is separated from the interior of the upper drawer 12 by a thin partition 80 extending under the evaporator 34 on the underside of the upper lid 32. The partition 80 is preferably impermeable such that air flowing around the evaporator 34 cannot mix with air inside the upper drawer 12. However it would be possible to bleed some cold air from the evaporator 34 into the upper drawer 12 if desired, for example through apertures in the partition 80.

So, there is minimal or no insulation in the floor 44 of the upper drawer 12 between the two drawers 12, 14; between the slots 68, 70 and the interior of the upper drawer 12; and across the partition 80 between the evaporator 34 and the interior of the upper drawer 12. This allows heat to be removed from the upper drawer 12 as shown at 82, without the need for forced air cooling into the upper drawer 12.

Condensation forming on the rear internal wall 72 of the upper drawer 12 may be collected in an inclined channel 84 that extends across that wall 72, near the floor 44 of the upper drawer 12. Similar drainage provisions may be made on the floor 44 of the upper drawer 12 and in the upper lid 32 under the partition 80. Condensate collected in this way can be conveyed to a defrost water collection and evaporation tray above the compressor 30 of the appliance in conventional manner. A sensor (not shown) may detect when either drawer 12, 14 is open, and close a valve to block air flow to or from the slots 68, 70 in the upper drawer 12 in order to conserve energy.

Thus, again, cold air from the evaporator 34 in the upper lid 32 also cools the interior of the lower drawer 14, hence obviating a second evaporator for the lower drawer 14. However in this case, the upper and lower drawers 12, 14 may be at substantially dissimilar temperatures so that one may be configured as a freezer and the other as a refrigerator, hi this case it is most appropriate that the drawer 14 whose interior receives cold air flow is a freezer and that the drawer 12 whose interior is cooled by conduction into that air flow through walls or partitions is a refrigerator. Of course, there may still be provision for variable temperature in each drawer 12, 14.

Many variations are possible within the inventive concept. For example, a similar arrangement could be applied to side-by-side drawers to reduce heat gain into the interior of the drawers.

It is much preferred that cooling is introduced via the lid or via the underside of an upper drawer as this leaves the drawers free of cooling connections to move and to be removed; however, this is not essential to the invention in its broadest sense. Similarly, evaporators are merely examples of cooling means. For example, cold air can be pumped into a drawer from a fan coil unit outside the drawer, either mounted in the lid or externally. It is also possible to employ other cooling means such as Peltier devices or magnetic refrigeration.

The seals mentioned in this specification are preferably sliding seals, for example the magnetic sliding seals disclosed by the Applicant in WO 2005/024315. However the Applicant has shown how to combine drawer movement with non-sliding seals, for example in WO 01/20237 and WO 02/073107 which show how a minor vertical movement of the drawer or the lid can clear the seals for subsequent horizontal movement of the drawer. The Applicant has also shown in WO 2006/021819 that open-topped refrigerated containers can move unconventionally, such as drawers that swing relative to a lid about a vertical axis and drums that swing relative to a Hd about a horizontal axis. All such arrangements are encompassed by this invention in its broad sense.

Claims

1. A cold-storage appliance including:

at least one insulating container being movable with respect to a supporting structure for opening and closing and comprising a plurality of walls each defining a respective external surface portion; and

a cooling means adapted to cool the interior of the closed container;

wherein when the container is moved to a closed position, a seal extending around an external surface portion of the container seals that external surface portion against exposure to air moving over the exterior of the container.

2. The appliance of Claim 1, wherein the seal is attached to the container around the associated external surface portion to move with the container.

3. The appliance of Claim 1, wherein the container moves away from the seal upon opening.

4. The appliance of any preceding claim, wherein the container is open-topped.

5. The appliance of Claim 4, wherein an insulating lid closes the open top when the container is moved to the closed position.

6. The appliance of Claim 5, wherein the lid is fixed to the structure.

7. The appliance of Claim 5 or Claim 6, wherein the cooling means is associated with the lid.

8. The appliance of Claim 4, wherein when the container is moved to the closed position, a wall of another container closes the open top.

9. The appliance of Claim 8, wherein said other container has insulating walls but the wall that closes the open top is substantially less insulating or non-insulated.

10. The appliance of Claim 8 or Claim 9, wherein said other container has one or more apertures in the wall that closes the open top.

11. The appliance of any preceding Claim, wherein the air moving over the exterior of the or each container is ambient or heated air.

12. The appliance of Claim 11, further comprising an impeller for driving air flow over the exterior of the or each container.

13. The appliance of any preceding claim, wherein an external surface portion of the or each container is sealed to an adjacent container of the appliance, to a lid of an adjacent container of the appliance, to an opposed cabinet wall of the appliance, or to a wall beside the appliance.

14. The appliance of Claim 13, wherein the adjacent container or lid, or the opposed cabinet wall, or the wall beside the appliance, is insulated at least in the region opposed to said external surface portion.

15. The appliance of any preceding claim, wherein at least one wall of the or each container is substantially less insulating than other walls of the container.

16. The appliance of Claim 15, wherein the less insulating wall is substantially non- insulated.

17. The appliance of Claim 15 or Claim 16 when appendant to Claim 13 or Claim 14, wherein said external surface portion is defined by the less insulating wall.

18. The appliance of any preceding claim, wherein the or each container is generally cuboidal.

19. The appliance of any preceding claim, wherein the sealed external surface portion is substantially planar.

20. The appliance of any preceding claim, wherein the walls of the or each container comprise a floor and a plurality of upright walls upstanding from the floor that together define an open top.

21. The appliance of Claim 20, wherein the upright walls of the or each container include side walls and a rear wall.

22. The appliance of Claim 21, wherein the side walls are mutually parallel and lie in planes parallel to the direction of opening and closing movement of the container.

23. The appliance of any of Claims 20 to 22, wherein an external surface portion defined by the floor of an upper container is sealed to an opposed lid of a lower container of the appliance.

24. The appliance of any of Claims 20 to 22, wherein an external surface portion defined by the floor of an upper container is sealed around the open top of a lower container of the appliance.

25. The appliance of Claim 24, wherein the floor is penetrated by at least one aperture permitting air to flow between the upper and lower containers.

26. The appliance of Claim 25, wherein a valve means responsive to the opening of either container is operable to close the or each aperture of the floor.

27. The appliance of any preceding claim and having first and second containers, wherein cooled storage volumes of the containers are in mutual communication when closed.

28. The appliance of any preceding claim and having first and second containers, wherein cold air is conveyed in use from the cooling means to one container via the other container.

29. The appliance of Claim 28, wherein a wall of the first container includes at least one duct or aperture that, when the first container is closed, communicates with the cooling means and with the interior of the second container to convey cold air from the cooling means to the second container.

30. The appliance of Claim 29, wherein cold air passes through a cooled storage volume of the first container to a cooled storage volume of the second container.

31. The appliance of Claim 29 or Claim 30, wherein cold air passes through a wall of the first container en route to the second container.

32. The appliance of Claim 31, wherein said wall of the first container partitions the cooled storage volume of the first container from the cooled storage volume of the second container.

33. The appliance of Claim 31 and comprising at least one duct in said wall of the first container, the duct being separated from the cooled storage volume of the first container.

34. The appliance of Claim 33, wherein the duct extends transversely with respect to the thickness of the wall.

35. The appliance of Claim 33 or Claim 34, wherein the duct supplies cold air downwardly from the cooling means into an open top of the second container.

36. The appliance of any of Claims 33 to 35, wherein the duct extends from a first plenum chamber around the cooling means to a second plenum chamber communicating with the second container.

37. The appliance of Claim 36, wherein the second container has an open top closed by the first container, and the second plenum chamber is disposed in the underside of the first container.

38. The appliance of Claim 37, wherein a diffuser partially defines the second plenum chamber.

39. The appliance of any of Claims 33 to 38, wherein the duct is positioned substantially closer to the cooled storage volume of the first container than to the exterior of that container.

40. The appliance of Claim 39, wherein substantially more insulation is disposed between the duct and the exterior of the container than is disposed between the duct and the cooled storage volume of the container.

41. The appliance of any of Claims 33 to 40 and comprising at least one air supply duct leading from the cooling means to the second container and at least one air return duct leading to the cooling means from the second container.

42. The appliance of any of Claims 33 to 41 and having a sensor to detect when either container is open, and a valve responsive to the sensor to block cold air flow through the duct in that event.

43. The appliance of any of Claims 28 to 42, wherein the first container is cooled by conduction of heat through at least one internal surface of the first container, that heat then being transferred to cold air flowing from the cooling means to the second container.

44. The appliance of any of Claims 28 to 43, wherein the first container is cooled by conduction of heat through a wall of the first container adjoining the second container, that heat then being transferred to cold air supplied by the cooling means to the second container.

45. The appliance of any of Claims 28 to 44, wherein the first container is cooled by conduction of heat through a partition between the cooling means and a cooled storage volume of the first container, that heat then being transferred to cold air emanating from the cooling means.

46. The appliance of Claim 45, wherein the partition is impermeable such that air emanating from the cooling means is segregated from air inside the first container.

47. The appliance of Claim 45, wherein the partition is permeable such that air emanating from the cooling means may be bled into the first container.

48. The appliance of any of Claims 28 to 47, wherein the first container is configured as a refrigerator and the second container is configured as a freezer.

49. The appliance of any preceding claim, further comprising a condensation removal duct communicating with the sealed external surface portion.

50. The appliance of Claim 49, wherein the condensation removal duct extends from the sealed external surface portion into the interior of the container.

51. The appliance of Claim 49 or Claim 50, wherein the condensation removal duct is closable by a valve that opens when the container is closed.

52. The appliance of any preceding claim, further comprising trace heating means operable to warm the sealed external surface portion.

53. The appliance of Claim 52, wherein operation of the trace heating means takes place when a container is open.

54. The appliance of any preceding claim and having first and second containers, wherein one of said containers is configured as a refrigerator and the other of said containers is configured as a freezer.

55. The appliance of Claim 54, wherein there is greater insulation between the sealed external surface portion and a cooled storage volume of the freezer container than between the sealed external surface portion and a cooled storage volume of the refrigerator container.

56. The appliance of any preceding claim, wherein the container has blast-chilling or thawing functionality.

57. The appliance of any preceding claim, wherein the seal is magnetic.

58. The appliance of any preceding claim, wherein the seal is a sliding seal.

59. The appliance of any preceding claim, wherein the seal creates a vapour seal.

60. The appliance of any preceding claim, wherein the cooling means comprises an evaporator, a cold air duct, a Peltier device or a magnetic refrigerator.

61. The appliance of any preceding claim, wherein the container tapers away from the opening direction of the container.

62. The appliance of Claim 61, wherein the container has upper and lower interface surfaces, either or both of which are inclined relative to the horizontal.

63. The appliance of any preceding Claim, wherein the container is supported by horizontally-extending runners whereby the container can be moved for opening and closing and supported when closed or open.

64. The appliance of Claim 63, wherein the container is a drawer that translates between closed and open positions.

65. The appliance of any of Claims 1 to 62, wherein the container is a drawer that moves between closed and open positions by swinging relative to the lid about a substantially vertical pivot axis.

66. The appliance of any of Claims 1 to 62, wherein the container is a drum that moves between closed and open positions by swinging relative to the lid about a substantially horizontal pivot axis.

67. A cold-storage appliance including: first and second insulating containers being movable with respect to a supporting structure for opening and closing; and

a shared cooling means for cooling the interiors of the first and second containers;

wherein, in use, cold air is supplied from the cooling means via the first container to the second container.

68. The appliance of Claim 67, wherein a wall of the first container includes at least one duct or aperture that, when the first container is closed, communicates with the cooling means and with the interior of the second container to convey cold air from the cooling means to the second container.

69. The appliance of Claim 67 or Claim 68, wherein cold air passes through a cooled storage volume of the first container to a cooled storage volume of the second container.

70. The appliance of any of Claims 67 to 69, wherein cold air passes through a wall of the first container en route to the second container.

71. The appliance of Claim 70, wherein said wall of the first container partitions the. cooled storage volume of the first container from the cooled storage volume of the second container.

72. The appliance of Claim 70 and comprising at least one duct in said wall of the first container, the duct being separated from the cooled storage volume of the first container.

73. The appliance of Claim 72, wherein the duct extends transversely with respect to the thickness of the wall.

74. The appliance of Claim 72 or Claim 73, wherein the duct supplies cold air downwardly from the cooling means into an open top of the second container.

75. The appliance of any of Claims 72 to 74, wherein the duct extends from a first plenum chamber around the cooling means to a second plenum chamber communicating with the second container.

76. The appliance of Claim 75, wherein the second container has an open top closed by the first container, and the second plenum chamber is disposed in the underside of the first container.

77. The appliance of Claim 76, wherein a diffuser partially defines the second plenum chamber.

78. The appliance of any of Claims 72 to 77, wherein the duct is positioned substantially closer to the cooled storage volume of the first container than to the exterior of that container.

79. The appliance of Claim 78, wherein substantially more insulation is disposed between the duct and the exterior of the container than is disposed between the duct and the cooled storage volume of the container.

80. The appliance of any of Claims 72 to 79 and comprising at least one air supply duct leading from the cooling means to the second container and at least one air return duct leading to the cooling means from the second container.

81. The appliance of any of Claims 72 to 80 and having a sensor to detect when either container is open, and a valve responsive to the sensor to block cold air flow through the duct in that event.

82. The appliance of any of Claims 67 to 81, wherein the first container is cooled by conduction of heat through at least one internal surface of the first container, that heat then being transferred to cold air flowing from the cooling means to the second container.

83. The appliance of any of Claims 67 to 82, wherein the first container is cooled by conduction of heat through a wall of the first container adjoining the second container, that heat then being transferred to cold air supplied by the cooling means to the second container.

84. The appliance of any of Claims 67 to 83, wherein the first container is cooled by conduction of heat through a partition between the cooling means and a cooled storage volume of the first container, that heat then being transferred to cold air emanating from the cooling means.

85. The appliance of Claim 84, wherein the partition is impermeable such that air emanating from the cooling means is segregated from air inside the first container.

86. The appliance of Claim 84, wherein the partition is permeable such that air emanating from the cooling means may be bled into the first container.

87. The appliance of any of Claims 67 to 86, wherein the first container is configured as a refrigerator and the second container is configured as a freezer.

88. The appliance of any of Claims 67 to 87, wherein at least one of the containers is open-topped.

89. The appliance of Claim 88, wherein said open-topped container is the first container.

90. The appliance of Claim 88 or Claim 89, wherein an insulating lid closes the open top when the container is moved to the closed position.

91. The appliance of Claim 90, wherein the lid is fixed to the structure.

92. The appliance of Claim 90 or Claim 91, wherein the cooling means is associated with the lid.

93. The appliance of any of Claims 88 to 92, wherein the second container is open- topped and when the second container is moved to the closed position, a wall of the first container closes the open top.

94. The appliance of Claim 93, wherein said wall of the first container is sealed around the open top of a second container.

95. The appliance of Claim 94, wherein the seal is magnetic.

96. The appliance of Claim 94 or Claim 95, wherein the seal is a sliding seal.

97. The appliance of any of Claims 94 to 96, wherein the seal creates a vapour seal.

98. The appliance of any of Claims 93 to 97, wherein the wall of the first container that closes the open top is non-insulated or substantially less insulating than other walls of the first container.

99. The appliance of any of Claims 93 to 98, wherein the first container has one or more apertures in the wall that closes the open top.

100. The appliance of Claim 99, wherein a valve means responsive to the opening of either container is operable to close the or each aperture.