WO1998035191A1

WO1998035191A1 - Evaporator making method, such evaporator and use thereof

Info

Publication number: WO1998035191A1
Application number: PCT/IT1998/000018
Authority: WO
Inventors: Gerard Hutter
Original assignee: Raco S.P.A
Priority date: 1997-02-10
Filing date: 1998-02-09
Publication date: 1998-08-13
Also published as: AU5878398A; ITUD970029A1; IT1291271B1

Abstract

Evaporator made by support sheet (1) to which a piping coil (21) with squashed section (2) is made adhere in which one or the other have a superficial layer of braze-welding material which melts with temperature and welds the two elements (1b) forming a single body. In this way a product of high quality and reliability at low costs is obtained.

Description

DESCRIPTION EVAPORATOR MAKING METHOD, SUCH EVAPORATOR AND USE THEREOF

Technical Field The present invention has for object a method for the making of an evaporator for refrigeration plants and respective evaporator or apparatus which includes it. The invention finds particular even if not exclusive application in the field of the refrigerators, freezers, and of the conditioning plants both for domestic and industrial use and in land, sea and air vehicles etc. As the apparatus which includes the evaporator is meant both the whole refrigerating circuit (for example with condenser and compressor) and a part of it (for example with the respective capillary tube integrated), and the apparatus which includes said refrigerating circuit as for example a refrigerator, a freezer, an air-conditioner. Background Art In prior art said evaporators are made in different ways, but mainly by welding of two metal sheet foils, generally a plane one and a shaped one, which welded together, make up the large sectioned channelling (generally coil shaped), where a capillary tubule having small diameter opens so that the duct passing to the larger section causes the expansion of the refrigerating gas and then the cooling. On the other side of the circuit obtained into the evaporator a tube with a section larger than the capillary and smaller than the evaporator piping section is engaged, which leads to the compressor, where the gas sucked and heated by compression, is cooled by exchange at room temperature in a condenser, for then passing again at closed circuit in said capillary, where it evaporates when the cycle is repeated. The art of this structure has the drawback of having many defects for the risk of leaks in the welding areas between the two plates which make up said evaporator. For such reason there are some productions of refrigerating circuits wholly made up with piping in copper or aluminium or galvanized iron or other material or suitable alloy, in which the length concerning the evaporation area is obtained by welding of the respective piping on a support sheet which acts as an extension of the heat exchange surface and possibly also as a support or container when it is folded as a box or as a compartment (e.g. "U" shaped). In such case the fixing of the piping length of the refrigerating circuit in contact with the sheet is obtained either by spot welding, or by gluing by conductive sealing paste (e.g. addition of metal dust as inert filling), or by latten flasks or U bolts (e.g. omega shaped) in their turn welded to the fins of the respective sheet, otherwise the piping is maintained adherent to the sheet by means of adhesive tape. If these solutions have the advantage of avoiding dangers of leaks, they have the great drawback of having a low conductivity with the sheet which fixes the piping of the refrigerating circuit because: - The spot welding does not give a suitable adherence and transmission between tube and sheet. - The gluing or sealing does not ease an heat exchange between tube and sheet for the known limitation of the plastic or organic materials to the heat transmission, without considering the brittleness of the plastic material at the low temperatures whose vibrations may also cause breakings. - The fixing by flasks is difficult and expensive and being there only one contact line (between tube and the sheet plane surface), the heat exchange is always reduced. - The fixing by adhesive tape has minor performances of heat exchange and besides it does not guarantee a sure fastening of the piping to the sheet in time. Solutions were considered for extending the tube contact surfaces with the sheet by its squashing. It is obvious that the larger heat exchange surface in the evaporator is given by the sheet surface and much less by the piping surface. This solution, though, even if advantageous does not guarantee an optimal heat exchange between tube and sheet because of the lack of close contact between the two exchange surfaces (tube-sheet). Purpose of the present invention Purpose of the present invention is that of obviating the above mentioned drawbacks and improving the performance of said exchanger also improving the production system and reducing the wastes. Disclosure of the invention This and other purposes are reached as claimed by a method for the making of an evaporator for refrigeration plants and respective evaporator or apparatus which includes it, of the type in which a refrigerating circuit piping which is fixed and made adhere to one heat exchange metal sheet surface is produced, characterized in that: - said refrigerating circuit piping is squashed at least in the length in which it must be made adhere to said metal sheet so that there is a contact plane by adherence between tube and sheet surface; - said piping at least in the adherence length and/or said sheet at least in the respective adherence surface, have a superficial layer of braze- welding material; - said piping is pressed in adherence to said sheet and subjected to temperature up to the melting of said surface layer of braze-welding material so that this same may melt and move by capillarity and surface tension thus gathering itself preferably between the tube-sheet contact surfaces. Advantages of the invention In this way the immediate advantage is obtained: - obtaining a sure assembling between the two elements; - having the maximum heat exchange between the two surfaces; - reducing at the minimum the finished product's defects and in particular the leaks, guaranteeing anyway a maximum yielding; - being able to reduce the costs, by mechanizing the production system. Description of a preferred form of embodiment These and other advantages will appear from the following description of preferred embodiment solutions, with the aid of the enclosed drawings, whose execution details are not to be considered as limitative but only given as examples. Figure 1 is a partial view of the refrigerating circuit concerning the part of the evaporator. Figure 2 is a sectional enlarged view of one part of the evaporator, showing the assembling modality by using the sheet covered by weld material for braze-welding. Figure 3 is a view like in previous figure in which the melting of the weld material (completed braze-welding between piping and sheet) has occurred. Figure 4 is a sectional enlarged view of one part of the evaporator, showing an alternative assembling way by using the piping covered by weld material for braze-welding. Figure 5 is a view like in previous figure in which the weld material melting (completed braze-welding between piping and sheet) has occurred. Figure 6 is a schematic view of the process for preparing the refrigerating circuit piping length concerning also the capillary tube. Fig. 7 is a schematic view of the production and assembling cycle of the respective piping length (2) to be assembled with the evaporator 1. Referring to Figure 7 station "A" it is schematically shown also that the roll tube is squashed in the section by drawing and/or rolling, so that it gets a shape having at least one plane surface length as shown in figures 2,3,4,5. This plane surface will extend the contact surface for a better heat exchange between tube 2 and sheet 1. Tube 2 may be pre-covered by braze-welding material (2b) for example by dipping as shown in Fig. 4, or otherwise the sheet ( 1) will be pre- covered by braze-welding material (lb) as shown in Fig. 2. After the shaping, tube and sheet move forward along two lines parallel to station "A" where tube 2 will be coil-like shaped 21 and the sheet in tape will be cut in squares 11; The following passage will be at the assembling station of the evaporator 12 (Station "B"). In said station the piping coil 2-21 will be pressed against the sheet surface 1 (Fig. 2/4) for having a sure adherence and it will be subjected to temperature up to the melting of the braze-welding layer ( lb/2b). The braze-welding material ( lb/ 2b), fluid, by capillarity and surface tension, will gather around the contact surfaces between tube 2 and sheet 1, as shown in Figures 3 or 5. After cooling, the evaporator will pass to the station "C" for the control. Subsequently it will pass to the assembling station "D" with the other part of the refrigerating circuit 3 involving the engagement also of the respective capillary on one side and of the piping which leads to the condenser on the other side. Then there will be a passage to a station "E" for the control of leaks and functionality of the whole circuit. Finally it will pass to the following stations for the final preparation (not shown) as for example ends plugging, varnishing, packaging, etc.

Claims

Claims 1. Method for the making of an evaporator for refrigeration plants, of the type in which a refrigerating circuit piping (2) is made which is fixed and made adhere to an heat exchange metal sheet surface ( 1), characterized in that: - said refrigerating circuit piping (2) is squashed at least in the length in which it must be made adhere to said metal sheet ( 1) so that there is a contact plane by adherence between piping (2-21 ) and sheet surface (1); - said piping at least in the adherence length (2-21) and/or said sheet ( 1 ) at least in the respective adherence surface, have a superficial layer of braze-welding material ( lb/2B); - said piping (21) is pressed in adherence to said sheet (1) and subjected to temperature up to the melting of said superficial layer of braze- welding material ( lb/2b) so that this same may melt and move by capillarity and surface tension thus gathering itself preferably between the tube-sheet contact surfaces.

2. Evaporator made by the method according to claim 1., characterized in that it is made up of: - at least one support sheet 1; - at least a piping length with squashed section (2) made adhere to the surface of said sheet; - the contact surface between piping (2) and the sheet ( 1) is wholly covered by braze-welding material (lb/2b).

3. Refrigerating circuit involving at least one evaporator according to previous claim.

4. Refrigerator provided with at least one evaporator according to previous claim.

5. Freezer provided with at least one evaporator according to previous claim.

6. Conditioner provided with at least one evaporator according to previous claim.