Field of the Invention

The present invention relates to improvements in openface coolers, and also to a door designed to be suitable for use in combination with openface coolers.

Background of the Invention

Openface coolers, also known as open deck coolers/refrigerators or open face refrigerators, consist of a cabinet without doors and with a refrigeration unit arranged to circulate chilled air to keep product displayed on open shelves in the cabinet below a predetermined temperature. The chilled air usually is circulated from the top of the cabinet as an air curtain down the open front of the cabinet. Openface coolers are widely used as point-of-sale displays for chilled goods, and it is important that the goods are clearly visible and that access to the goods is easy.

The energy losses from coolers of this type can be significant, especially if the coolers are located where there are frequent drafts, e.g. people walking past the display. Any turbulence in the nearby airflow tends to suck cold air out of the cabinet and thus increases the energy requirement of the cabinet. Since energy costs are constantly increasing, it is desirable to reduce energy losses, but any reduction in energy losses should not be at the expense of reducing the visibility of the goods displayed, or making it awkward to access the goods.

Many openface coolers are fitted with "night blinds" which are opaque insulating roller blinds which can be drawn down the front of the cooler at night, when goods are no longer being sold from the cooler. However, blinds of this type cannot be used when the goods are to be sold.

Conventional refrigerator doors are made from insulated sheet metal panels, and are opaque. Transparent refrigerator doors are known, and are made from double glazed glass panels. Doors of this type are expensive to manufacture and are heavy:- they cannot really be fitted as a temporary measure but must be fitted permanently. Object of the Invention

An object of the present invention is the provision of a door which can be fitted to an openface cooler, which reduces energy losses from the cooler without significantly reducing the visibility of the goods displayed, and which is lightweight and relatively inexpensive.

Disclosure of the Invention

The present invention provides a door for an openface cooler, wherein the door includes at least one perforated panel adapted to slide across the open face of the cooler, said panel including an aperture substantially larger than any one of the perforations, to allow inflow of air into the cooler; and wherein said panel is made of or includes transparent or translucent material.

The present invention also provides a door for an openface cooler, wherein the door includes two or more perforated panels, each adapted to slide across the open face of the cooler, each panel including an aperture substantially larger than any one of the perforations, to allow inflow of air into the cooler; each panel is made of or includes transparent or translucent material.

As used herein, the term 'perforation' means that a hole is formed right through the thickness of the panel.

Preferably, each aperture is at or adjacent the upper edge of the corresponding panel.

The door may also include one or more fixed perforated panels, but preferably the two or more sliding perforated panels form the whole of the door and are dimensioned such that they cover substantially all of the open face of the cooler.

The present invention further provides an openface cooler fitted with a door as described above. Detailed Description of Preferred Embodiments

By way of example only, preferred embodiments of the present invention are described in detail, with reference to the accompanying drawings, in which:-

Figure 1 is a front view of an openface cooler in accordance with a first embodiment of the present invention, with two shelves for displaying product indicated in broken lines; the remainder of the shelves are omitted for clarity;

Figure 2 is a front view of a single panel of the door, on a larger scale;

Figure 3 is a diagrammatic sectional side view, showing airflow patterns in the cooler in use; and

Figure 4 is a front view similar to Figure 1 , but showing a further embodiment.

Referring to Figure 1-3 of the drawings, an openface cooler 2 is of known type and includes a refrigeration unit (not visible) mounted in the base 3 of the cabinet, and arranged to supply a stream of chilled air as a "curtain" down the front of the cabinet, adjacent the front of the shelves 6.

As shown in Figure 3, the chilled air curtain (shown as arrow A) enters the display area 4 of the cabinet through a vent 5 adjacent the front of the cabinet, at the top of the cabinet; the air then passes down the front of the shelves 6 and is drawn into a return duct 7 in the lower part of the cabinet. A fixed skirt panel 7a is secured across the lower front of the cabinet to help to guide returning air into the duct 7. The panel 7a usually is fitted to known open-front cabinets, but can be omitted from the cabinet of the present invention.

The chilled air curtain is of cold air, and tends to be at very low velocity at the very front face of the cabinet. For this reason it has been found that if the open face of the cabinet is closed off by a completely solid, transparent, but un-insulated door, the inner surface of the door quickly becomes obscured by condensation because the door is warm relative to the temperature of the air curtain. This significantly reduces the visibility of the goods displayed on the shelves 6.

With this invention, the problem of condensation forming on the door is overcome by creating an induced airflow over and through the door in strategic places; essentially a "breathing" door. This is achieved by providing a door 10 which is formed from panels 11 ,12 which are perforated and which are formed with an aperture at or near their upper edge, or other positions as determined by the specific internal airflow design of a cabinet. This functions by allowing ambient air to be drawn into the beginning of the air curtain via appropriately placed door apertures 14, and the upper door perforations 14a. Ambient (relatively warm) air is drawn through the apertures 14 and the perforations 14a by the motion of the air curtain past the side of the apertures and perforations on the inner door surface, which creates a pressure difference across that area, with a higher pressure on the outside of the door and a lower pressure on the inside of the door, drawing ambient air into the cabinet adjacent the inner door surface. The ambient air entering the cabinet in this way tends to be moved downwards, adjacent the inner door surface, by the movement of the air curtain, and as the ambient air moves downward, it mixes slightly with the air forming the air curtain, causing the air curtain air to warm and thus expand:- this increases the air pressure lower down the inside surface of the door. As a result, the air pressure inside the cabinet is higher on the inside of the door on the lower part of the door and this causes the air to move outwards through the lower perforations, as shown in Figure 3. The combination of the perforations 13, 14a, and apertures 14 is effective in reducing condensation on the inner surface 8 of the door to an acceptable level.

In the preferred embodiment shown in the drawings, the door 10 is formed by two panels 11 ,12 of equal size, each with an aperture 14 in the form of a smoothly curved scoop formed in the upper edge of the door. However, each aperture 14 may be any of a wide range of shapes and positions. On each of the panels 11 ,12, the perforations are distributed over the whole of the door surface, with the central perforations possibly arranged to form a pattern. It will be appreciated that the pattern is purely for decorative purposes. The door may also carry decorations or advertising material or pricing information.

The number of perforations used, the distribution of the perforations across the surface of each panel, and the size and shape of the aperture 14, depend upon a number of factors including: the size and shape of the panel; the rate of flow of the chilled air curtain; the average difference between the ambient temperature and the temperature within the cabinet. For satisfactory performance, the object is to achieve the right mix between the cold internal air circulated by the air curtain and the relatively warm ambient air being drawn down the inside surface of the panels through the apertures 14 and the upper perforations 14a. This means that although the perforations do not need to be uniformly spread across the panel, they should nevertheless be distributed across the panel so that there is air flow across the full area of each door. If there are too few perforations and/or the perforations are not distributed all over the panel, there will be insufficient circulation of the warm ambient air over the inside surface of the panel, and condensation will result. Alternatively, if there are too many perforations, chilled air will tend to escape from the cabinet as well as warm air, and the efficiency of the cabinet will be impaired.

Similar considerations apply to the size and shape of the aperture 14 in each panel:- it must be a sufficient size and shape to admit sufficient ambient air to keep substantially all of the panel free of condensation, but if the aperture 14 is too large, too much ambient air will be admitted and again the efficiency of the cabinet will be impaired.

Example

The open front of a chiller measures 758mm (height) x 820mm (width); the front is closed off by a door formed from two perforated sliding panels as shown in figures 1-3. Each panel has an approximate size of 764mm x 430mm. Perforations are distributed over substantially the whole surface of each panel, on a square grid layout. Each perforation is a circular hole approximately 5mm in diameter, and the area of the perforations is in the range 3% to 4% of the total surface area of each panel.

Each panel is formed with an aperture 14 at the top edge of the panel; the aperture is a segment of a circle and the distance between the lowest point of the aperture and the top edge of the panel is approximately 35 mm; the length of each aperture 14 is 390mm.

The above described arrangement works well in practice, to give a door substantially free of condensation with a rate of air flow of approximately 1.0 metres/second and a temperature difference between the air curtain and the ambient air of approximately 15°C - 25°C. The panels 11 ,12 are mounted in upper and lower tracks 15,16 (Figure 1 only) to form a sliding door. The door 10 may of course be formed from more than two panels, and for larger cabinets, some of the panels could be fixed, providing adequate access to the goods could be achieved. The panels 11 ,12 are formed with handle apertures 17 in known manner.

Preferably, the panels 11 ,12 are made of a suitable transparent or translucent material, e.g. a plastics materials such as polycarbonate or acrylic, or glass. However, the panels 11 ,12 could be made of a non-transparent/translucent material and be formed with inserts of transparent or translucent material, so that the cabinet contents remain visible.

It should be emphasised that the panels 11 ,12 do not need to form an airtight seal over the face of the cabinet:- doors of this type are impractical for cabinets in constant use. Instead, the panels 11 ,12 simply are arranged to cover most of the open face of the cabinet:- this has been found sufficient to significantly reduce the energy requirement of the cabinet, whilst maintaining easy access to the contents and good visibility of the contents.

Openface cabinets in accordance with the present invention may be manufactured with the door 10 already fitted. Alternatively, existing openface cabinets which were manufactured without doors can have doors and door tracks retrofitted.

Once the door panels have been fitted to the cabinet, they can be easily removed and replaced, since the panels simply lie in the tracks 15,16. This means that, if desired, the panels can be removed from the cabinet during especially busy periods.

It will be appreciated that the number of door panels 11 ,12 used for any given chiller can be varied depending upon the size and shape of the chiller. For small to medium- sized chillers, two panels work well, but more panels may be appropriate for larger chillers.

Another possibility is illustrated in Figure 4:- in this embodiment, a door 20 is formed from three panels:- two fixed panels 21 ,22 arranged one on each side a sliding panel 23. All three panels 21-23 are formed with perforations 13 and apertures 14 as described with reference to Figures 1-3. Sliding panel 23 is formed with handle apertures 17 and is mounted on tracks, in the same manner as described with reference to Figures 1-3, and can be slid to one side or the other as indicated by arrows X, to allow access to the interior of the chiller.

Doors for any size of chiller may include fixed panels in addition to one or more sliding panels. Unless the fixed panels are very small in width compared to the sliding panels, the fixed panels are perforated and apertured in the same manner as the sliding panel or panels.

Any of the door configurations described above assist in minimising the loss of air curtain air out of the cabinet, and also limit the impact of outside influences (e.g. drafts) created by movement around the cabinet.