GB2198220A

GB2198220A - Refrigeration display cabinet

Info

Publication number: GB2198220A
Application number: GB08722285A
Authority: GB
Inventors: Roy Prentis
Original assignee: Barker George & Co Ltd
Current assignee: Barker George & Co Ltd
Priority date: 1986-09-27
Filing date: 1987-09-22
Publication date: 1988-06-08
Anticipated expiration: 2007-09-22
Also published as: GB8623287D0; GB8722285D0; GB2198220B

Abstract

A refrigerated display cabinet, with front access and an air circulation cooling system, includes a casing defining a first chamber 2 for the display of foodstuffs and having an evaporator 12 for cooling air and a second chamber 5 having a mechanical means 14 of a refrigeration unit 16. The display cabinet also includes two impelling means 20; 17, 18, one for each chamber, for circulating the air. The air circulation thus has a first and second part: the first part is within the first chamber passing the evaporator 12 and the second part is through the second chamber 5 passing the mechanical means 14 of the refrigeration unit to cool the same. Air of the first part therefore provides an air curtain 29 for the front access of the first chamber and an air flow for inside said chamber cooling the foodstuffs retained therein, whereas air of the second part creates an insulation layer to the open face of the air curtain and additionally gathers cooled spill air from the first part and entrains and chills ambient air. The mechanical means cooling air is warmed such that it has an increased capacity to take up defrost water from a cascade system 13. <IMAGE>

Description

Refrigerated Display Cabinet This invention relates to a refrigerated display cabinet.

The invention relates especially but not exclusively to display cabinets with front access and particularly to the air flow which maintains such display cabinets in a cool or refrigerated condition.

The refrigeration system generally employed in such display cabinets comprises a motor driven compressor, a condenser, a fan to move air across the condenser to improve its efficiency, an expansion system and an evaporator. The evaporator is traditionally in communication with a cooled chamber in which, for example, foodstuffs are displayed and stored.

In order to keep the display area cool, it is usual to provide cold air circulation over the evaporator and thereafter into the display area. In our Patent GB 2,126,697 A, a refrigeration system is described wherein a single insulating air curtain is provided across the open front of the cabinet to insulate the display area from the ambient air temperature and to keep the display area at a lower temperature, and wherein a perforated rear screen, in combination with deflectors and shelving, spills cool air over and creates eddy currents around the foodstuffs.The efficiency of this system was increased by passing the cooled air, once it had circulated around the foodstuffs, over the relatively hot compressors and condensers, using the then warmed air to evaporate defrost water passing over a cascade as described in detail in our Patent GB 1,460,450 2n~ im~rovez upon in our British Patent Application 8618270.

In use, such known refirgeration systems work efficiently up to an optimum level of cabinet volume generally a volume sufficient to accommodate foodstuffs on four shelves and a base tray.

One disadvantage of such conventional systems is that they are unable to cope when the cabinet volume is greater than the optimum in order to accommodate a greater number of shelves and hence more foodstuffs. This increased volume correspondingly increases the surface area of the air curtain such that the air is unduly warmed by prolonged contact with ambient air and by passage over the compressors and condensers.

The object of this invention is to obviate or mitigate this disadvantage.

According te the present invention there is provided a refrigerated display cabinet having a front access and an air circulation cooling system, said cabinet comprising a casing defining a chamber, a refrigeration unit having mechanical means and an evaporator for cooling the air, and impelling means for circulating the air, said air circulation having a first and second part, the first part of which is within the chamber and passes the evaporator and the second part of which is outwith the chamber and passes the mechanical means of the refrigeration unit, in which the first part also provides an air curtain for the front access of the chamber and an air flow for inside said chamber and in which the second part creates an insulation layer to the open face of said air curtain and gathers cooled spill air from the first part and entrains and chills ambient air to cool the mechanical means of the refrigeration unit.

Preferably, there are impelling means for each part of the circulation; the impelling means may be in the form of a fan.

Preferably, a second chamber is situated beneath the first chamber of the cabinet, with the impelling means of the second part situated in the second chamber, and drawing in entrained ambient air and gathering spill air to cool the mechanical means of the refrigeration unit; preferably, said air is drawn in through an air filter.

Preferably, the air of the second part entrains the ambient air by the pull of the impelling means, aided by a undercanopy moulding guiding the ambient air and by the drag of the air curtain.

Preferably, the warmed discharge air of the second chamber rises to dispelling means at a high-level.

The drawing in of a mixture of chilled ambient air and cooled spill air at a low-level and the discharge of warmed air at a high-level causes a circulation of air, helping to create the cabinet's own local environment.

Preferably, a rear screen of the chamber conceals a first compartment with the evaporator and a second compartment with impelling means for air of the first part, both evaporator and impelling means being in the path of the air circulation of the interior chamber; most preferably, the rear screen is perforated and most preferably sloped.

Preferably, some air of the first part issues outwardly, either upwardly or downwardly, from the rear screen deflected by shelving in the chamber; preferably, some air is channelled through ducting in the shelves. The deflected and channelled air either meets the air curtain and contributes to it or creates eddy currents in spaces beneath the shelves.

Preferably, the deflective shelves and the shelves with ducking are interchanaeable.

Preferably, a side screen is provided at each end of the chanber, said screens also being perforated at least in part.

Preferably, the refrigeration unit comprises an evaporator, a condenser, a compressor and a cascade system for defrost water.

The advantage of the present invention is that the volume of the display chamber is increased and this is achieved by rectric=i the primary circulation of air to the interior chamber and the evaporator means, and aided by firstly the provision of additional eddy currents by the through-shelf ducting and secondly the use of high speed fans which increase the case air speed and thus prevent prolonged contact with warm air or foodstuffs. The second circulation is important as it cools the powered refrigeration means, aids in the removal of defrost water from the cascade syste r, sets up a local air circulation, and insulates the increased surface area of the open face of the air curtain from the ambient air temperature.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a a sectional side elevation through a refrigerated display cabinet according to the present invention; Fig. 2 is a front elevation of a half of a rear screen of Fig. 1; Fig. 3 is an enlarged view of perforations of Fig. 2; Fig. 4 is a left hand side screen of the refrigerated display cabinet according to the invention; and Fig. 5 is a right hand side screen of the refrigerated display cabinet according to the invention.

Referring to the drawings, there is provided a refrigerated display cabinet 1 for the storage and display of foodstuffs, the cabinet 1 having a first or interior chamber 2 bounded by a canopy 3, end walls (not shown), a hollow rear section 4 and a second or low-level chamber 5 which lies beneath the first chamber 2. The front 6 of the first chamber 2 is open to allow access by members of the public or staff to the foodstuffs which are supported on a base tray 7 or shelves g in a display area 9. A sloped rear screen 10 both delimits the rear of the display area 9 and conceals a two-chambered rear cavity 11 and an evaporator 12. The second chamber 5 contains a cascade system 13, as discussed in detail in our Patent GB 1,460,450, and mechanical means 14 of a refrigeration unit 16 comprising twin condensers 15, impelling means in the form of two fans 17, 18 in parallel and a twin "Hermetic" compressor system 19.

The cabinet 1 is constructed so as to provide two circulations of air, an interior circulation within the interior chamber 2 and an exterior circulation around the outside of the chamber 2, these circulations being represented in Fig. 1 by solid and dashed arrows respectively.

The interior circulation has two circuits, a primary and a secondary represented in Fig. 1 by double or single arrowheads respectively. Air of both circuits removes heat and moisture from the interior chanmber. The primary circuit provides a flow of cool air over the surface of foodstuffs displayed on the shelves 8 and creates eddy currents. The secondary circuit provides an air curtain 29 over the open front 6 of the chamber 2 insulating the air of the primary circuit from ambient air.

Impelling means in the form of a high speed axial fan and mounting box 20, draws air from both circuits through the two-chambered rear cavity 11, the air being prevented from straying from one chamber 21 to the other chamber 22 by a stepped horizontal divider 23. The fan 20 also blows the air over a base channel 24, which is provided for collecting and delivering defrost water 25 to the cascade system 13, and then over the evaporator 12.

After passing over the evaporator 12, the air of the primary circuit exudes into the display area 9, in an evenly distributed fashion, through a lattice pattern 51 of perforations 53 in each half 52 of the rear screen 10. Each perforation 53 is 3.18 mm in diameter. Some of the air exuding through the perforations 53 cumulates downwardly and outwardly from beneath the lowermost shelf 8 to the base 31.

Some air passes over deflectors 32 at the top of each shelf 8, whilst the rest spills downwardly and outwardly through in-shelf ducting 34 which channels the air to lipped outlets 35 on the undersides of certain shelves 8. This produces eddy currents.

Air of the primary circuit also travels to the hollow end walls (not shown) of the cabinet 1 to exude through L-shaped lattice patterns 54 of perforations 53 positioned on the side screens 55, 56, each of these perforations 53 being 7.14 mm in diameter. Air also exudes through two larger holes 57, each 25.4 mm in diameter, that are placed such that air tumbles into the base 31. In addition, air passes through a circular aperture 58 of 12.7 mm diameter in the left hand screen 55 and a rectangular aperture 59 of 120 x 97 cm in the right hand side screen 56.

Air of the secondary circuit, after passing over the evaporator 12, is deflected so as to gather close to the rear wall 26 and pass to a channel 27 beneath the canopy 3 and thereafter through a honeycombed outlet 28 so as to provide the air curtain 29 by passing downwardly over the open front 6. The air curtain 29 of the secondary circuit not only isolates and insulates the display area 9 but also maintains the eddy currents of the primary circuit.

Eventually air of the two circuits mix and are drawn through a grilled inlet 30 to be recycled.

Returning now to the exterior air circulation, impelling means in the form of the fans 17, 18 draws air through an air filter 41 and into the second chamber 5. In the second chamber 5 it passes over the condensers 15 and compressors 19, which heat the air and reduce its relative humidity such that it has an increased capacity to take up water from the cascade 13 and also a tendency to rise. It rises up the hollow rear section 4 of the cabinet to be discharged by high-level dispelling means in the form of nozzles 36. An underside 37 of an outward extension of the canopy 3 of the cabinet 1 is moulded such that ambient air has a tendency to be entrained by the action of fans 17, 18 and by the drag of the adjacent curtain of air 29 of the interior circulation.

The entrained ambient air becomes the descending interface of a temperature exchange system. This not only insulates the interior circulation from the ambient air temperature but also chills the entrained ambient air such that the entrained ambient air can subsequently cool the mechanical means 14 of the refrigeration unit 16. The exterior circulation also entrains any spill air 38 from the interior circulation; indeed, such dehumified air is of particular use as, on being warmed, it has an increased capacity for evaporating the defrost water 25 from the cascade system 13.

The workings of the herein described refrigerated display cabinet are enhanced by a temperature probe (as discussed in our Patent Application GB 2,167,603 A), a thermostat (discussed in our Patent Application GB 2,126,697 A) and the aforementioned cascade system 13. It is further enhanced by the condensate cooling of the condenser pipework 39 in the condenser tray 40 beneath the cascade system 13; by solid state switching of the compressor motors 19; by manual service intervention of defrost control; by dual case temperature switching incorporating automatic temperature alarm up-dating; by microprocessor control of compressors including lead cycling to reduce wear and for capacity control, defrost sequencing and terminations on demand, and f-malt indication, including direct read-over of temperature for service diagnosis; and by a composite arrangement of interface cards and programmable controller, incorporating the electronic thermostat within a common enclosure.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

1. A refrigerated display cabinet having a front access and an air circulation cooling system, said cabinet comprising a casing defining a chamber, a refrigeration unit having mechanical means and an evaporator for cooling the air, and impelling means for circulating the air, said air circulation having a first and second part, the first part of which is within the chamber and passes the evaporator and the second part of which is outwith the chamber and passes the mechanical means of the refrigeration unit, in which the first part also provides an air curtain for the front access of the chamber and an air flow for inside said chamber, and in which the second part creates an insulation layer to the open face of said air curtain and gathers cooled spill air from the first part and entrains and chills ambient air to cool the mechanical means of the refrigeration unit.

2. A display cabinet according to Claim 1, wherein there are impelling means for the first and the second parts of the air circulation.

3. A display cabinet according to either Claim 1 or 2, wherein the second chamber is situated beneath the first chamber cf the cabinet, with the impelling means of the second part situated in the second chamber in the cabinet drawing in entrained ambient air and gathered spill air to cool the mechanical means of the refrigeration unit.

4. A display cabinet according to any one of the preceding Claims, wherein a under-canopy moulding aids the entrainment of the ambient air.

5. A display cabinet according to either Claim 3 or 4, wherein the discharge air of the second chamber rises to dispelling means at a high-level.

6. A display cabinet according to any one of the preceding Claims, wherein a rear screen of the chamber conceals a first compartment with the evaporator and a second compartment with impelling means for air of the first part, both evaporator and impelling means being in the path of the air circulation of the interior chamber.

7. A display cabinet according to Claim 6, wherein the rear screen is perforated.

8. A display cabinet according to any one of Claims 6 to 8, wherein air of the first part issues outwardly from the rear screen of the chamber and some is deflected by shelving and some is channelled by ducting in shelves.

9. A display cabinet according to Claim 9, wherein shelves deflecting air and the shelves with ducting are interchangeable.

10. A display cabinet according to any one of the preceding Claims, wherein a side screen is provided at each end of the chamber, said screens being perforated at least in part.

11. A display cabinet as hereinbefore described with reference to the accompanying drawings.