EP0125642A2

EP0125642A2 - Refrigerator having an improved condenser

Info

Publication number: EP0125642A2
Application number: EP84105304A
Authority: EP
Inventors: Agostino Bravin
Original assignee: Industrie Zanussi SpA
Current assignee: Industrie Zanussi SpA
Priority date: 1983-05-16
Filing date: 1984-05-10
Publication date: 1984-11-21
Also published as: EP0125642A3; IT8334024V0; ES279235Y; ES279235U

Abstract

A refrigerator, particularly of the domestic type, comprising a compressor and an evaporator is provided with a condenser (4) formed substantially in one piece of an internally and externally smotth-walled tube (8) bent to a meander configuration. The bent portions (10) of tube 8 are of circular cross-sectional shape (9), while rectilinear portions (11) thereof are of substantially elliptic cross-sectional shape (12). The bent portions (10) are clamped in lateral supports (13, 14) of substantially U-shaped cross-sectional configuration provided with lugs (15 to 18) for securing the condenser to the frame of the refrigerator (5).

Description

The present invention relates to a refrigerator, particularly for domestic use, comprising a compressor, an evaporator and an improved condenser for liquifying a refrigerant provenient from the compressor in a gaseous state and feeding it to the evaporator in the liquid state.
Known condensers are generally secured to the rear wall of the refrigerator and are formed of tubular conduits bent to a meander configuration having elements for augmenting its heat-exchange surface brazed thereto, such as louvred metal sheets, wires or ribs of various types.
Manufacture of condensers of this type involves a number of manual brazing operations requiring the employ of spezialized labour and slowing up the production rate.
In addition, in the brazed zones of the condenser, the constraints and stresses resulting from the assembly of the condenser with the refrigerator may result in the development of cracks which in the long run may give rise to corrosion and leakage and make it appear inconvenient to subject the condenser to anticorrosive treatments more effective than the conventional varnish coating.
In conventional condensers, moreover, the possibilities of dimensional adaptation to various refrigerator production models are limited not only by the constant pitch of the meander configuration, but also by the standard width of the louvred sheets which have to be variably dimensioned between one model and the other,, whereby their manufacture is undesirably diversified. It is further to be noted that the louvred sheets are generally applied to the condenser tube in the form of vertically extending strips welded or brazed to each other along their abutting edges. This manner of securing the louvred sheets results in variations of the contact areas between the louvred sheets and the condenser tube and thus in a non-uniform distribution of the heat-exchange coefficient.
Another drawback results from the fact that condensers of this type have to be installed at a certain inclination with respect to the rear wall of the refrigerator, whreby the depthwise dimension of the latter is undesirably increased. Also to be considered is the fact that the louvred sheets are easily deformed and tend to generate noise during operation of the refrigerator while rendering the periodically necessary external cleaning of the refrigerator unduly cumbersome.
In the case of so-called wire condensers, to the meander tube of which metallic wires extending at right angles to the tube axis are electro-welded in an automatized process, there are obtained certain advantages as compared to condensers provided with louvred sheets, although there remain certain of the above described basic shortcomings which, together with nearly doubled production costs, render the employ of such wire condensers disadvantageous.
As an alternative to these types of condensers it is also possible to employ tubes provided with integrally formed internal and/or external ribs or fins projecting in darial directions and extending parallel to the axis of the tube or along helical lines.
The employ of such finned tubes involves high production costs and considerable difficulties in bending the tubes. It is also to be noted that external fins form an obstacle to the ascending flow of the cooling air rising from the lower sections of the tube to the upper ones, whereby the thermal efficiency of the condenser is impaired.
It is therefore an object of the present invention to provide a condenser for domestic refrigerating appliances which is adapted to be formed as a one-piece construction, permits the employ of simple materials and manufacturing equipment, and requires a reduced amount of labour for its manufacture.
Another object of the invention is the provision of a condenser of the type defined above which is capable of dissipating the varying amounts of heat generated by refrigerating appliances of different capacity without the need for louvres, wires or fins.
A still further object is to eliminate the need for any welding operations in the manufacture of a condenser of the type defined above so as to simplify its manufacture, avoid the employ of specialized personnel and permit the application of various anti-corrosion treatments more efficient than the conventional varnish coating.
These and other objects are attained according to the invention in a refrigerator, particularly for domestic use, comprising a compressor, an evaporator, and a condenser adapted to transmit an elevated temperature between a fluid circulating internally thereof and an external fluid of natural circulation, and to be secured to the outer rear wall of the refrigerator, by providing that said condenser is formed substantially integrally of a tube having smooth internal and external surfaces and bent to a meander configuration having a circular cross-sectional shape at its bent portions and an elliptic cross-sectional shape at its rectilinear portions.
The characteristics and advantages of the refrigerator according to the invention will become more clearly evident from the following description with reference to the accompanying drawings, wherein:

fig. 1 shows a diagrammatic perspective rear view of a refrigerator according to the invention,
fig. 2 shows a diagrammatic view of a preferred embodiment of a condenser for the refrigerator of fig. 1, and
fig. 3 shows an enlarged cross-sectional view of a part of the condenser taken along the line III-III in fig. 2.

Shown in fig. 1 is an exemplary embodiment of a domestic refrigerator 5 according to the invention provided with a condenser 4 secured to its outer rear wall. Condenser 4 is connected between a compressor.6 and an evaporator 7 of a conventional refrigerating circuit and is formed substantially in one piece of a tube 8 (fig. 2) having smooth internal and external surfaces and being bent to a meander configuration extending in a substantially vertical plane.
Tube 8 is of circular cross-sectional shape 9 (fig. 3) at its bent portions 10, while its rectilinear portions 11 are of substantially elliptic cross-sectional shape 12.
By way of a non-limiting example, meander configuration 8 may be formed of a simple metal tube 8 the diameter of which is considerably greater than that of a tube employed for forming a conventional condenser.
Tube 8 is made to pass between two oppositely disposed cylindric rolls the spacing of which is reduced at predetermined intervals so as to deform the circular cross-sectional shape 9 of tube 8 to an elliptic cross-sectional shape 12 along predetermined longitudinal portions, the cross-sectional area enclosed by these sections being substantially equal to that of the tubes of conventional condensers provided -with louvres or wires.
More specifically, the portions of tube 8 having circular cross-sectional shape 9 are relatively short and located at predetermined intervals corresponding to bent portions 10 of tube 8, while rectilinear portions 11 extending between bent portions 10 are of elliptic cross-sectional shape 12 and constitute the major part of the length of tube 8.
Due to the elliptic cross-sectional shape 12 of rectilinear portions 11, the cross-sectional area of these portions of tube 8 is reduced, while the external surface thereof remains unchanged resulting in an increased heat exchange coefficient between the internal fluid and the external air.
In laboratory experiments it has been found that by comparison to a conventional louvre or wire condenser of the same overall dimensions, the condenser according to the invention is capable of dissipating the same amount of heat, although its outer heat exchange surface is smaller.
The condenser according to the invention may be secured to the frame of refrigerator 5 by means of two lateral supports 13, 14 (figs. 1 and 2) of substantially U-shaped cross-sectional configuration (fig. 3), adapted to be compressed into clamping engagement with the circular cross-sectional shape 9 of bent portions 10 of tube 8 so as to be secured thereto without welding or brazing.
Supports 13 and 14 each comprise at least two metal lugs 15, 16 and 17, 18, respectively, formed integrally therewith or welded thereto, these lugs being formed with suitable perforations for the passage of threaded fasteners or rivets or the like (not shown) for securing the assembly to the frame of refrigerator 5.
As an alternative, lugs 15 to 18 may be formed of a synthetic resin or the like and attached to supports 13, 14 by snap-engagement therewith.
It is thus evident that the condenser according to the invention lends itself to being manufactured by a manufacturing process which may be carried out in a simple manner with a minimum employ of manual labour and equipment and which is capable of being completely automatized.
As the formation of condenser 4 of tube 8 does not require any welding operations, the tube may be subjected to anti-corrosion treatments, for example zinc or chromium plating, which are considerably more efficient than a simple varnish coating.
It is further to be noted that the plate-shaped overall configuration of condenser 4 without any procecting components permits condenser 4 according to the invention to be mounted in a perpendicular position. In addition, this configuration of condenser.4 results in a considerably dimensional flexibility, reduced space requirements and optimum stability characteristics.
For connection of condenser 4 to the refrigerant circuit, the ends of tube 8 may be reduced in diameter in a per se known manner, permitting them to be connected, as by brazing, to other conduits of smaller diameter. As an alternative, the ends of tube 8 may be provided with connector elements such as internal and/or external sleeves, bushings or the like.
The described condenser may obviously be modified in various manners without leaving the scope of the present invention as set forth in the claims.

Claims

1. A refrigerator, particularly for domestic use, comprising a compressor, an evaporator and a condenser adapted to transmit an elevated temperature between a fluid circulating internally thereof and an external fluid of natural circulation, and to be secured to the outer rear wall of the refrigerator, characterized in that said condenser (4) is formed substantially integrally of a tube (8) having smooth internal and external surfaces and bent to a meander configuration having a circular cross-sectional shape (9) at its bent portions (10) and an elliptic cross-sectional shape (12) at its rectilinear portions (11)

2. A refrigerator according to claim 1, characterized in that said condenser (4) comprises two lateral supports (13, 14) each having a U-shaped cross-sectional configuration and being adapted to be compressed so.as to clampingly engage at least a part of the circular cross-section (9) of said bent portions (10) of said meander configuration (8), and at least two lugs (15, 16; 17, 18) formed of metal or synthetic resin integrally with said supports or secured thereto by a snap-engagement and provided with suitable perforations for the passage of fastener elements for securing said condenser (4) to the frame of the refrigerator (5) by threaded or snap-engagement therewith.