Method for producing evaporators for refrigeration circuits, and the evaporator obtained

Abstract: A method for producing evaporators for refrigerators, especially domestic refrigerators, said evaporators comprising a hairpin coil (1) having rectilinear portions (1A) and an adhesive-coated metal sheet (5) for their fixing to the refrigerator compartments; the hairpin coil (1) is coupled to the face of a first metal sheet (4) by deforming this latter in correspondence with zones of contact with the hairpin coil (1), and is then coupled, together with said sheet (4), to one (5A) of the two adhesive-coated faces (5A, 5B) of a further metal sheet (5) such that the hairpin coil (1) is interposed between and coupled to the metal sheets (4, 5), which are also directly coupled together.

Description: This invention relates to a method for producing evaporators for refrigeration circuits, in particular for domestic refrigerators. It also relates to the evaporator obtained. Both the method and the resultant evaporator are of the type stated in the introduction to the accompanying main claims, to which reference should be made. GB-A-1 432 134 discloses a method in which the tubing of an heat exchanger and an adhesive are disposed between two metal sheets, these latter being subsequently pressed together to deform at least one of the sheets. FR-A-2 541 759 discloses an evaporator comprising a metallic plate supporting the coil, and a plastic heat shrinkable sheet covering the coil and the plate. Document GB-A-769 929 describes a method for producing an evaporator by pressing tightly the evaporator coil into grooves of a first plate. These grooves have to be manufactured on the plate before the pressing operation. The main object of the present invention is to provide a method enabling economical evaporators to be produced which are more adaptable to the refrigerator compartment even if the surfaces of this latter are not flat, are not dependent on the manual ability of the operator (an hence free from problems of inadequate repeatability) and are able to be assembled as an independent component (and transportable as such for example to another factory), and moreover providing more effective heat absorption from the refrigerator compartment. This and further objects which will be apparent from the ensuing description are attained by a method and evaporator in accordance with the teachings of the accompanying claims. The invention will be more apparent from the detailed description of a preferred embodiment thereof given hereinafter by way of non-limiting example and illustrated on the accompanying drawing, in which: Figure 1 is an example of a hairpin coil forming part of the evaporator of the invention; Figure 2 is a schematic perspective view of the tool used to implement the method of the invention; Figure 3 is a schematic cross-section through the tool during a first stage of the method of the invention; Figure 4 shows the same section as Figure 3 during another stage of the method of the invention; Figure 5 is a detailed partial cross-section through the evaporator on termination of the method of the invention, before the evaporator is removed from the tool; Figure 6 is a schematic cross-section through the evaporator obtained. In the figures, the reference numeral 1 indicates the hairpin coil which constitutes the basic element of the evaporator. It comprises a series of rectilinear portions 1A connected together by curved portions 1B and approximately parallel to each other. The hairpin coil is formed from a tube the cross-section through which (see Figure 5) comprises an arcuate part 2 (preferably in the form of a circular arc) and a flat part 3. The manner in which the tube is bent into hairpin form is conventional and will not be described. The evaporator of the invention also comprises two thin metal sheets 4, 5, for example of aluminium, having a thickness for example of 0.15 mm, these being applied to opposite sides of the hairpin coil. The sheets 4, 5 adhere to the hairpin coil and together in that one of them (ie the sheet 5) is provided with a layer of adhesive (5A in Figure 5 in which this layer is represented by a thicker line). In addition, the sheet 5 which adheres to the flat part 3 of the tube forming the hairpin coil is also provided with a layer of adhesive 5B on its outer face, this layer being protected by a repellent sheet 6 (for example of silicone-coated paper) which is removed when the evaporator is to be fitted to the refrigerator compartment, the outer layer of adhesive (5B) then remaining joined to the compartment. The metal sheets 4, 5 are preferably dimensioned so as to cover the rectilinear portions 1A but not the curved connection portions 1B, as shown in Figure 1, in which the edges of the sheets are shown by dashed lines and indicated by Z. The method for producing the evaporator of the invention uses a tool or template 10, shown schematically in perspective view in Figure 2 and being in the form of a plate provided with a series of rectilinear grooves 10A corresponding, in terms of arrangement and length, with the rectilinear portions 1A of the hairpin coil 1 and having a cross-section substantially the same as the tube of the hairpin coil (as can be seen from Figure 5). The flat metal sheet 4 is rested on the tool 10 (Figure 3). On the tool covered in this manner there is placed the hairpin coil 1 such that its rectilinear portions 1A coincide with the grooves 10A in the tool. Using presser means, for example a roller 20, the rectilinear portions 1A of the hairpin coil are pressed into the grooves 10A in the tool (Figure 4) to at the same time obtain permanent deformation of the sheet 4 and its application to the wall of said grooves. After this pressing operation and consequent shaping of the sheet 4 on the hairpin coil 1, the resultant unit on the tool 10 has an outer surface 21 which can be considered substantially flat. The sheet 5, provided with the adhesive layer (5A, 5B) on both its faces, one of which is protected by the repellent silicone-coated sheet 6, is spread over the surface 21 with that face not protected by the silicone-coated sheet 6 in contact with said surface. Then in the aforestated manner, ie by exerting pressure on the sheet 5 through the silicone-coated protection sheet 6, an intimate joint is achieved via the adhesive between the sheet 5, the flat part 3 of the tube of the hairpin coil and the sheet 4 (where the sheet 5 adheres to this), as shown in Figure 5. The evaporator is hence complete and is removed from the tool on which it has been produced, ready for application to the refrigerator compartment itself when the refrigerator production requires it, after removing the protective silicone-coated layer 6, by applying thereto that side of the adhesive layer 5B of the metal sheet 5 which was previously protected by the silicone-coated sheet. When applying the evaporator to refrigerator compartments for example of polymer material, it can be easily shaped and adapted to the compartment surface. The evaporator produced by the method of the invention has the merit of being an independent component which can be stored or transferred to another factory, and is repeatable in the sense that each evaporator is identical to the others. Although the evaporator of the invention has been described with reference to a hairpin coil formed from a tube of substantially semicircular cross-section, the advantages of the invention can also be obtained with tubes of different cross-section, for example elliptical, and with tools or templates which also involve the curved portions 1B of the hairpin coil 1.

Claims: A method for producing evaporators for refrigerators, especially domestic refrigerators, said evaporators comprising a hairpin coil (1) having rectilinear portions (1A) interposed between and coupled to two metal sheets by means of an adhesive and by deforming at least one of said sheets in correspondence with zones of contact with the hairpin coil (1), characterised in that the hairpin coil (1) is coupled to a first metal sheet (4) by deforming such first sheet by pressing the hairpin coil (1) into grooves (10A) of a tool (10) and then coupled to a second metal sheet (5) having two adhesive-coated faces (5A, 5B), one of the adhesive-coated faces (5B) of the second metal sheet (5) being used for fixing the evaporator to a refrigerator compartment. A method as claimed in claim 1, characterised in that the second metal sheet (5) is protected on one face (5B) by a removable sheet (6) repellent to the adhesive. A method as claimed in claim 2, characterised in that the tool (10) is provided with rectilinear grooves (10A) corresponding substantially to rectilinear portions (1A) of the hairpin coil (1) and to the cross-section through the relative tube, on said tool (10) there being firstly laid the first metal sheet (4) and then the hairpin coil (1), the rectilinear portions (1A) of which are pressed into said rectilinear grooves (10A) to obtain a unit having a substantially flat exposed surface on which is applied the second sheet (5), the outer face of which is protected by the repellent sheet (6). An evaporator for refrigerators, in particular domestic refrigerators, manufactured according to a method of claim 1, in which a hairpin coil (1) is interposed between two metal sheets (4, 5), a first sheet (4) which has been deformed into the grooves (10A) of a tool (10) by pressing with the hairpin coil (1), said first sheet (4) being provided with shaped portions cooperating with the hairpin coil, the second metal sheet (5) being coupled to the first sheet by means of an adhesive, wherein the second sheet (5) is adhesive-coated on both sides (5A, 5B), one (5A) of said sides being flat and being rigid with the hairpin coil and with the first metal sheet (4) and the other enabling the evaporator to be fixed to a member or structure of the refrigerator. An evaporator for refrigerators as claimed in claim 4, characterised in that one (5B) of the sides of the second sheet (5) is protected by a removable repellent sheet (6). An evaporator for refrigerators as claimed in claim 4, characterised in that the hairpin coil (1) is formed from a tube having an arcuate part (2) and a flat part (3), the first metal sheet cooperating with the arcuate part of the tube of the hairpin coil (1), the second metal sheet (5), which is flat and adhesive-coated on both its sides, being rigidly joined to the flat part (2) of the tube of the hairpin coil (1).

Inventors: GASPERINI SERGIO, SCOMAZZON ANGELO, GASPERINI, SERGIO, SCOMAZZON, ANGELO, Gasperini, Sergio, c/o Whirlpool Europe s.r.l., Scomazzon, Angelo, c/o Whirlpool Europe s.r.l.
Applicants: WHIRLPOOL CO, WHIRLPOOL CORPORATION
Application year: 1997
Main classification: F25B39
IPC codes: B23P15, F28F1, F25D23, F25B39, B21D53