EP1517106A1

EP1517106A1 - Refrigeration apparatus with improved defrost water evaporation arrangement

Info

Publication number: EP1517106A1
Application number: EP03021387A
Authority: EP
Inventors: Luigi Paroni
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2003-09-22
Filing date: 2003-09-22
Publication date: 2005-03-23

Abstract

Refrigeration apparatus comprising at least an externally mounted condenser, at least an evaporator associated to a circuit (2) for the conveyance of defrost water, an externally provided pan adapted to collect said defrost water, and associated means adapted to cause said water to evaporate, consisting of an extended section (5) of said externally mounted condenser adapted to be submerged in said pan, and which is sheathed in a sleeve closed along its central portion and made of impermeable material, preferably aluminium. Said extended section of said condenser and said sleeve may be produced in close contact each other.

Description

The present invention refers to an improved kind of refrigeration apparatus, which comprises an evaporator and, in general, a refrigerating circuit adapted to operate according to well-known principles and in well-known manners.
Largely known and popular in the art is also the practice of carrying out the defrost phase of the evaporator either by means of an electric heating element, located in close proximity of the evaporator, or by making use of a spontaneous warming-up effect of the evaporator itself.
Regardless of the manner in which such a defrost phase may also be brought about, it in all cases implies an intermittent production of a certain amount of water, deriving from the frost on the evaporator surfaces being so caused to thaw, and various means and methods are used in this connection to then let this water out of the refrigerator for definitive elimination. One of the most commonly used methods to eliminate such a water consists in causing it to evaporate and, to such a purpose, it is a largely known practice to arrange on top of the compressor shell, which becomes very hot in use, a plastic pan into which said defrost water is in fact allowed to flow. The heat generated by the compressor, transferred to said pan and, from the latter, to the defrost water collected thereinto, causes the same water to eventually evaporate.
Such a method is well-known to all those skilled in the art, so that it shall not be explained or dealt with any further here.
Anyway, when adopted in a mass-production environment turning out products aimed at the household-appliance market under very tight competition-driven constraints, the above solution, although quite effective from a purely functional point of view, has manifested a number of practical drawbacks, i.e.:

real production normally requires refrigeration appliances to be manufactured with widely differing overall characteristics and, as a result, with the use of correspondingly differentiated component parts; this of course implies a marked variability in the types of compressors used, and this in turn gives rise to a distinct need for a corresponding multiplication in the types of evaporating pans to be provided and used; it can be readily appreciated that such a circumstance contributes to making things definitely worse as far as the manufacturing standardization is concerned, thus aggravating production costs in general, due to the need for a larger variety of parts to be held on stock and handled accordingly throughout the manufacturing process up to the marketplace;
another drawback derives from the fact that the efforts that are since a long time now being made in view of increasing the energy efficiency of refrigerator appliances in general, as well as the techniques that have been developed as a result of these efforts, have led current compressors to use smaller and smaller amounts of energy owing to both them being actually required to supply smaller amounts of cold and a definite improvement in their specific energy efficiency; as a final result of all these circumstances, compressors tend to heat up to a constantly decreasing extent and this makes it of course more difficult and troublesome for the evaporation pan to be adequately heated so as to cause the defrost water collected therein to evaporate in the required manner.

In order to overcome this problem, a largely known method consists in making use, to heat up the water in the evaporation pan, of a section of the pipe of the condenser that is usually arranged along the outer surface of the rear wall of the refrigeration appliance. In other words, a section of said condenser pipe is extended and given a suitable downwards shape, so that the lower outermost end portion thereof dips into the evaporation pan and, as a result, the defrost water collecting thereinto is heated up naturally and, therefore, caused to evaporate.
However, even this solution has a definite drawback in that the condenser pipe is usually made of iron or alloys containing iron in a high percentage; if this is submerged in water, it rapidly undergoes oxidation and resulting failure, with easily imaginable consequences.
In view of avoiding such a kind of problem, the practice has been largely adopted consisting in making that section of condenser pipe, which is intended for being submerged in the pan, through the addition of a corresponding section of copper pipe, which is generally known to effectively withstand oxidation and related corrosion processes.
Even this solution has however turned out as not being totally free of drawbacks. In fact, the added section of copper tube must be connected to the main condenser body, which is made of iron pipe, by means of two welding operations, which do not usually lend themselves to automation, i.e. cannot be automated, and therefore are rather expensive, so that they add new costs and complications to the manufacturing process in general, whereas all those skilled in the art are well aware of the fact that replacing the entire iron-pipe condenser with a comparable condenser made of copper tube is not an option, owing to the considerable additional costs that would have to be sustained.
It would therefore be desirable, and it is actually an object of the present invention, to provide a refrigeration apparatus, preferably a household refrigerator, with an evaporator equipped with a defrost heater and an outside pan for the collection and evaporation of defrost water, which is provided with specific devices adapted to favour such evaporation of the defrost water contained in said pan, and which does away with all of the afore-mentioned prior-art drawbacks.
Within this general object, it is a purpose of the present invention to provide a refrigeration apparatus which can be easily manufactured using existing, readily available techniques and means, and is capable of operating in a most reliable and safe manner.
According to the present invention, all these aims are reached in a particular kind of refrigeration apparatus provided with a pan for collecting defrost water and an external condenser according to the characteristics and features as recited in the appended claims, and as described in greater detail below by way of non-limiting example with reference to the accompanying drawings, in which:

Figure 1 is a symbolical, overall view of the arrangement of the devices for the evaporation of the defrost water in a refrigeration apparatus according to the present invention;
Figure 2 is a symbolical see-through and cut-away view of a condenser section according to the present invention;
Figure 3 is a perspective see-through view of a pan and a condenser according to the present invention;
Figure 4 is a view of an improved embodiment of the condenser shown in Figure 2;
Figure 5 is a view of a further improved embodiment of the condenser shown in Figure 3.

With references to the above-mentioned Figures, a refrigeration apparatus according to the present invention comprises an evaporator (not shown), below which there is provided an arrangement for collecting the defrost water dropping from the evaporator itself, as well as a circuit 2 (shown in part only) for conveying said defrost water into an external pan 3; this pan may or may not be associated to the compressor, so that this circumstance is practically of no relevance whatsoever to the purposes of the present invention.
Furthermore, said refrigeration apparatus is provided with an externally mounted condenser 4, which is made of preferably tubular elements of a per sé known kind.
A section 5 of said condenser 4, which is situated down below, i.e. on the lower side of the same condenser, as this is best shown in Figure 1, is extended and shaped so as to be able to dip into and pass through said pan 3, so that, when the same pan fills up with thawing water, it becomes submerged in the water so collecting thereinto.
According to the present invention, this extending section 5 of condenser pipe is not bare, but is rather covered by an impermeable sheathing or protective sleeve 6 provided all over the required length and in the necessary position, in such a manner as to ensure that no portion of this extended section 5 of condenser pipe that is likely to be covered by the water in the pan can actually come into contact with the same water. In other words, said extended section 5 of condenser pipe is protected by a tubular member, which may be made of any suitable material and be applied using any suitable method, as far as it is able to reliably ensure total protection against any possible contamination or contact with the water in the pan.
Said protective sleeve 6 can be effectively made using elastomeric materials which, thanks to the elasticity thereof, would at the same time automatically keep said sleeve firmly in the desired position.
As an alternative thereto, said sleeve can be also obtained by applying an impermeable protective coating on said section 5 all over the length thereof, eg. by applying an external protective paint coating or dipping said section 5 of condenser pipe into a bath of appropriate substances which, upon drying or hard-setting, are effective in ensuring full impermeability thereof to outside agents.
In particular, it has been found advantageous if said protective sleeve 6 is obtained with the use of an appropriately long aluminium tubing that is applied externally by putting it on the pipe 5 prior to its being given its desired or required shape. The advantage deriving from the use of such a material lies in the fact that aluminium does not oxidize and, therefore, is not attackable by water. Furthermore, aluminium is a sufficiently low-cost and easily processable material; it features an adequate plasticity at reduced thickness, so that it is easily deformed into shape, and above all has an excellent heat conductivity, so that it does not constitute any hindrance to a good heat transfer from the condenser to the water in the pan.
In an advantageous manner, so as this is shown schematically in Figure 4, said extended condenser pipe section 5 is given a wave-like shape, so as to increase the submerged (although not fully wetted) surface area thereof, without having to increase the size of the pan itself.
In the case that, as suggested above, the extended condenser pipe section 5 is protected by an aluminium sheath, the latter must be of course put on the same pipe section 5 prior to its being bent into the wave-like contour thereof, but this bending process does not anyway constitute any problem at all, considering the high deformability and toughness of aluminium.
Finally, in view of enhancing heat conduction between water and condenser pipe, it is particularly advantageous of said aluminium sleeve 6 is applied so as to be in close contact with the outer surface of said section 5 of the condenser pipe. This may be obtained with the use of various techniques known in the art; for instance, and with particular reference to Figure 5, upon having so protected the inner tube 5 through the application of the sleeve 6 having an adequately larger diameter with respect thereto, the latter is calked or rolled along a directrix thereof extending parallel to the axis O of the same tube, while drawing out part of the material of said sleeve 6 laterally so as to form, with such a material, a kind of side lip 7 that would anyway be of no practical hindrance at all.
Said rolling and the resulting shrinkage of the material of the sleeve 6 therefore cause the diameter thereof to be reduced so as to bring said sleeve closer to said section 5 of condenser pipe and, preferably, to establish a tight fit of said sleeve against said section 5 of condenser pipe, thereby achieving the desired improvement in heat conductivity.

Claims

Refrigeration apparatus, in particular a household refrigerator appliance, comprising:

at least an externally mounted condenser (4),

at least an evaporator,

which is associated to a circuit (2) for the conveyance of defrost water,

an externally provided pan (3) adapted to collect said defrost water, and associated to means adapted to cause said water to evaporate;

characterized in that said means adapted to cause said water to evaporate comprise:

a extended section (5) of said externally mounted condenser, which is adapted to be submerged in said pan, and

which is sheathed in a sleeve (6) closed along its central portion, in such a manner that said section (5) of said condenser to be submerged never comes into contact with the water contained in said pan.
Refrigeration apparatus according to claim 1, characterized in that said sleeve (6) is made of a material that is impermeable to water.
Refrigeration apparatus according to claim 2, characterized in that said sleeve (6) is made of aluminium tubing.
Refrigeration apparatus according to claim 3, characterized in that said extended condenser section and the related sheathing sleeve are formed into a wave-like contour (7) of the respective portion to be submerged.
Refrigeration apparatus according to any of the preceding claims, characterized in that the inner surface of said sleeve (6) and the outer surface of said extended condenser section (5) are substantially in close contact with each other.