AU631604B2 - Improved freezer - Google Patents

Description

631604 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION FOR OFFICE USE: Class Int.Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 0 0 a 0 o °o Priority: 0 Related Art: 0 n000 0 0 0 Name of Applicant: SIMPSON LIMITED Address of Applicant: 616 Torrens Road, Woodville North, South 00, Australia 5012, Australia 0 0 a Actual Inventor: Peter Russel Smith 04 0 Address for Service: SHELSTON WATERS, 55 Clarence Street, Sydney "o Complete Specification for the Invention entitled: 0 0. "IMPROVED FREEZER" The following statement is a full description of thil invention, including the best method of performing it known to us:- (Complete of PJ2991 dated 28th February, 1989) 1 27/02' ab~ f i 0 *I 0 0 i 00 0 o 0 S2 o Sos 0 The present invention relates to freezers as are generally used for preserving perishable foodstuffs. More particularly, the invention relates to an improvement to chest or cabinet freezers of the type including a serpentine length of evaporator tube within the freezer, or at least in a, heat exchange relationship with ai inside liner of the chest or cabinet, through which chilled refrigerant flows from a refrigeration unit, causing the inside of the chest or cabinet to be cooled.

The capacity of the unit must be sufficient to compensate for the low heat transfer efficiency from the air within the freeze-. to the evaporator tube. Whilst this efficiency is enhanced by providing a large transfer area inherent in a serpentine tube, the capacity required in order to maintain a predetermined temperature inside the freezer, or to rapidly restore that temperature after the.freezer has been opened and closed, is considerable and tlerefore the cost of 'unning the freezer is high.

In addition to the expense of operating such freezers, they are prone to internal frosting which further reduces the efficiency of the refrigeration unit in addition to enveloping the coutents of the freezer and thereby preventing clear identification of those contents.

So called "frost free" freezers have existed for several years and consist of a fan located outside the freezer chamber which continually redirects air from the freezer chamber over the evaporator and back to the chamber. The recirculating air helps keep the goods I ii within the chamber frost free and when the evaporator requires defrosting the temperature of the chamber is not affected as it is isolated from the evaporator. However, in order to run such a system a high performance evaporator is required and otherwise useable space is occupied by this evaporator and fan. The result is decreased efficiency and increased running and manufacture costs.

It is therefore an object of the present invention to provide an improved freezer which will substantially ameliorate at least some of the disadvantages of the prior art.

To this end, the present invention consists in a freezer including a freezer cabinet having a door; serpentine evaporator ductwork in thermally conductive contact with an inner liner of said freezer cabiint; and a circulation fan located inside the volume defined by said inner lining.

o 0 0 In a preferred embodiment the circulation fan is actuated simultaneously with a refrigeration unit which supplies cold refrigerant to the duct work.

A preferred embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawing being a cross-sectional side elevation of a chest freezer according to the present invention.

Referring to the drawing, a freezer 1 comprises a chest 2 having as a door a lid 3 which is hingedly 3attached to the chest 2 by hinges (not shown). A seal 4 is provided between the chest 2 and the lid 3 to provide a substantially air tight seal.

Both the chest 2 and the lid 3 have an inner lining and an outer casing 6. Insulating material 7 is sandwiched between the inner lining 5 and the outer casing 6 to assist in maintaining a reduced temperature within the chest.

A serpentine duct work 8 in the form of a tube is attached to the inner lining 5 for heat exchange 0 0' therebetween. It will, however, be appreciated that the duct work may be formed integral with the inner lining An electric circulation fan 9 is attached to the lid 3 to cause a draft of air within the chest 2.

The fan 9 is actuated simultaneously with a refrigeration unit which unit causes cold refrigerant to flow through the tube 8. The unit itself is I thermostatically controlled by conventional means.

The freezer 1 may additionally be provided with a switch which is tripped whilst the lid 3 is open to prevent the fan 9 from opeuating.

It has been found ,:hat the provision of fan 9 increases the heat transfer from the goods not direc'-ly in contact with the evaporator surface and thus the efficiency of tLa freezer 1 by increasing contact of the cooled air with the goods. This has the added benefit of preventing a build up of frost on the contents of the freezer. Furthermore, the faster freezing process helps 4 retain the freshness and goodness of the foods.

It will be appreciated by those skilled in the art that whereas the preferred embodiment is a chest freezer, a cabinet freezer including a circulation fan will fall with the scope of the present invention.

It will farther be appreciated that the circulation Sfan need not be mounted to the lid of the freezer but may be mounted elsewhere within the freezer.

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Claims (4)

1. A freezer including a freezer cabinet having a door; serpentine evaporator ductwork in thermally conductive contact with an inner liner of said freezer cabinet; and a circulation fan located inside the volume defined by the inner liner.

2. A freezer according to claim 1 wherein the fan is located on the door.

3. A freezer according to either claim 1 or 2 wherein the fan is actuated simultaneously with a refrigeration unit which supplies cold refrigerant to the duct work.

4. A freezer according to any one of the preceding claims further comprising a switch which prevents operation of said fan when the chest or cabinet is open. A freezer according to claim 4 wherein said switch o0 is tripped by opening of the door. S6. A freezer substantially as hereinbefore described Swith reference to the accompanying drawing. DATED this 18th day of September, 1992 SIMPSON LIMITED o Attorney: WILLIAM S. LLOYD o s SFellow Institute of Patent Attorneys of Australia 0 of SHELSTON WATERS Sa a 0 6 V1