US 2912230 A
Description (OCR text may contain errors)
Nov. 10, 1959 F. l. RATAICZAK REFRIGERATING APPARATUS Filed y 13. 1954 INVENTpR. Francis I. Rafalczak REFRIGERATIN G APPARATUS Francis I. Rataiczak, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 13, 1954, Serial No. 429,562 a 3 Claims. (Cl. 257-256) This invention relates to refrigerating apparatus and more particularly to a plate type evaporator and the method of manufacturing the same.
Considerable difliculty has been experienced in the manufacture of plate type evaporators for us in refrigerators of the type in which the evaporators are defrosted during each oif cycle. This difficulty results from the fact that it is diflicult to braze a tube to a plate Without producing objectionable cracks or voids in the metallic fillet between the tube and the plate. Moisture condenses in those voids which extend to the surface of the metal and the alternate freezing and thawing of this moisture causes these voids to become larger and larger until the metal surrounding the void ruptures. a refrigerant leak if the metal which ruptures happens to be the wall of the tubing forming the refrigerant line. It is an object of this invention to prevent such leaks from forming without attempting to eliminate such voids. More particularly it is an object of this invention to use an extruded tube which has a solid projection on its one side which may be brazed to a plate in such a manner that any cracks or voids which may form in the fillet of brazing material will not be formed close enough to the main tube wall to cause rupture of the tube Wall.
Thus it is an object of this invention to attach a refrigerant line to a heat transfer plate by means of a flange which is free from pores or cracks adjacent the refrigerant passage.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.
In the drawings:
Figure 1 is an elevational view of a plate type evaporator constructed in accordance with my invention; and,
Figure 2 is a fragmentary sectional view taken substantially on line 22. of Figure 1.
I Referring now to the drawing wherein a preferred embodiment of the invention has been shown, reference numeral generally designates a plate type evaporator or use in a modern refrigerator wherein the evaporator is automatically defrosted during each off cycle. This evaporator includes a substantially flat plate 12 which is preferably made of aluminum and has brazed thereto refrigerant tubing 14 into which refrigerant is supplied for refrigerating the plate. Plates of this type are adapted to be used in refrigerators of the type disclosed in Jacobs et al. Patent No. 2,672,023 to which reference is hereby made for a more complete disclosure of the system in which the evaporator is to be used.
The tubing 14 is preferably extruded aluminum which includes an integral projection 16 which is formed as a part of the main tubing when the tubing itself is extruded. The extruded tubing 14 is bent into the desired shape such as the serpentine shape shown in Figure 1 of the drawing with the integral projection 16 always facing in the same general direction. The tubing 14 is then placed adjacent to the plate 12 with the projection 16 ar- This rupture causes ranged in contact with the plate 12. The projection .16 is then brazed to the plate 12 by the use of suitable aluminum brazing material which forms a fillet 18 between the plate and the outer end of the projection 16 as shown in Figure 2. The outer end or edge of the projection 16 is preferably rounded as shown so that if in bending the tubing in serpentine shape the projection 16 does not always extend perpendicularly toward the plate 12,'the,re
will always be good contact between the plate 12 and the I rounded end portion of the projection 16. The thickness of the flange is preferably slightly greater than the thickness of the wall of the tubing so as to provide a good heat transfer path between the tube and the plate.
By virtue of the above described method and construction, it is obvious that any frost blister which may form as the result of any porosity in the fillet 18 will not be close enough to the wall of the refrigerant tube 14 to be capable of puncturing the wall of the refrigerant passage.
When a conventional piece of tubing is brazed to a flat plate by conventional brazing methods; the fillet of brazing material between the tube and the plate frequently contains minute cracks which are open at the surface and some of which extend into the interior of the brazing material. Moisture seeping into such a surface crack fills the crackand due to the frequent alternate thawing and freezing of the moisture, the crack gradually increases in size until it causes a break in the tube wall. Breaks of this type are eliminated by virtue of the construction shown in Figures 1 and 2 of this application.
Applicants construction does not attempt to eliminate the presence of surface cracks and voids in the fillet of brazing material as this has proven to be impossible from a practical standpoint. Applicants flange 16 removes the tubing surface far enough from the fillet of brazing material so that any frost blister which might form in the brazing material can break without causing any refrigerant leak.
While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.
What is claimed is as follows:
1 In an evaporator, a support element, a tube having said support, said flange extending a distance greater than the thickness of the wall of said tube throughout the width of said flange, and metallic means bonding said flange to said support, said flange serving to hold said support and said tube wall in spaced relationship from one another, at least a portion of said flange being interposed between the wall of said tube and said metallic bonding means by said flange over the entire area of said bonding means. 3. In an evaporator, a support element, a tube having a projecting flange provided with a rolled edge arranged adjacent said support, and means metallically bonding References Cited in the file of this patent said flange to said support, said flange serving to hold said UNITED STATES PATENTS support and said tube in spaced relationship to one an- 7 other, said projecting flange serving to increase the thick- 211711790 Hlgham P 1939 ness of the tube wall throughout the entire width of said 5 2,359,926 McCullough 101 1944 flange, at least a portion of said flange being interposed 213861889 Furry 1945 between the wall of said tube and said bonding means at 14441824 Han July 1948 the point where the wall is closest to said bonding means 2469'963 Groslean et a1 May 101 1949 2,718,383 Frenger Sept. 20, 1955 whereby the portion of the tube Wall closest to said bonding means is protected from rupture by the interposition 10 of said flange between said tube wall and said bonding means.