US2136641A - Refrigerating apparatus - Google Patents

Description

Nov. 15, 1938.

H. F. SMITH 2,136,641

REFRIGERATING APPARATUS File Dec- 21. 1936 a Sheets-Sheet 2 [W8 ATTORNEYS.

Mum.

Nov. 15, 1938. H. F. SMITH REFRIGERATING APPARATUS 3 Sheets-Sheet 3 Filed Dec. 21, 1936 3 mm T N m 3 V n W A X s m w ML Patented Nov. 15, 1938 u UNITED STATES REFRIGERATING APPARATUS Harry F. Smith, Dayton, Ohio, assignor to General Motors Corporation, tion of Delaware Dayton, Ohio, at corpora- Application December 21, 1936, Serial No. 116,944

2 Claims.

This invention relates to heat transfer devices and particularly to condenser constructions for'refrigerating systems.

' An object of my invention is to provide a heat exchanger of the type having a closed fluid conveying passage extending therethrough and which exchanger is of improved construction and increased eiiiciency.

Another object of my invention is to provide a heat exchanger comprising a plurality of parts adapted to be assembled together and bonded to ture to reduce the temperature gradient between certain portions of the heat exchanger.

A still further object of my invention is to increase the heat transfer efficiency of a heat exchanger to thereby obtain greater capacity from an exchanger of given size or to decrease the overall dimensions of an exchanger of a predetermined capacity.

In carrying out the foregoing objects it is a still further and more specific object of the invention to form certain portions of the fluid conveying conduits ofmy improved heat exchanger from strips of sheet metal that are bent or folded into the desired shape and have certain portions thereof secured together to provide parts of the fluid conduits with a plurality of closed passages.

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:

Fig. 1 isa front elevational view of a heat exchanger constructed in accordance with my invention;

Fig. 2 is an enlarged fragmentary end view of the heat exchanger taken'in the direction of the arrow 2 in Fig. 1 and showing the end portion partly in elevation and partly in section;

Fig. 3 is a fragmentary view of the heat exchanger partly in elevation and partly in section and taken on the line 33 of Fig.

Fig. 4 is afragmentary horizontal view of the heat exchanger taken on the line 44 of Fig. 2;

Fig. 5 is a fragmentary sectional view similar to Fig. 4 and taken on the line 55 of Fig. 6 showing a modifled end construction of the heat exchanger;

Fig. 6 is a fragmentary sectional view of the modified end construction of the heat exchanger taken on the line 6-6 of Fig. 5;

Fig. 7 is a plan view of a metal strip adapted to be stampedand formed to provide a fin element for the heat exchanger;

Fig. 8 is a sectional view taken on the line 8-8 of Fig. 7 through the metal strip after having apertures stamped therein; and

Fig. 9 is a fragmentary sectional view through a fin element formed from the metal strip disclosed in Fig. 8 in accordance withthe invention.

Referring to the drawings, for illustrating my invention, I have shown in Fig. 1 thereof a unitary heat exchanger generally represented by the reference character I ll, such for example as a condenser for the refrigerating system. The heat exchanger Ill comprises a plurality of superimposed and horizontally extending parallelly arranged closed refrigerant conveying conduits I l. The conduits ll extend beyond the exchanger proper and have pressed sheet metal cap members l2 secured to the ends thereof. A plurality of pipes or conduits l3 secured to certain of the cap members I2 connect the refrigerant conveying conduits H in communicative relation toprovide a series flow for refrigerating fluid through the condenser or exchanger Ill. The condenser l0 may be provided with inlet and outlet pipe connections l4 and I5 respectively at one end thereof. The heat exchanger 10 also comprises a fin arrangement for augmenting the transfer of heat from fiuid in conduits II to the air or other cooling medium for the fluid and this arrangement includesa plurality of fins IS. A metal plate I! is secured to the fins l6 at the top and bottom of the exchanger l0 and these plates have flanges l8 extending outwardly therefrom which serve as mounting means for the exchanger orfor connecting same in an enclosed path of air such as to a shroud or the like in which is mounted an air circulating fan or blower.

Referring now to Fig. 2 of the drawings it will be noted that the fluid conduits ll extending through the heat exchanger III are flattened as at 2| to provide a relatively fiat elongated passage for the flow of refrigerant therein. After the tubes or conduits I l have been flattened a strip of metal 22 corrugated as at 23 is inserted in each of the conduits. The corrugations is formed in metal strip 22 provide flat portions 23 which lie against or abut the walls of conduit ll. Metal strip 22 thus serves to d1- vide the refrigerating fluid fiowing through conduit ll into a plurality of paths of flow to thereby awment the transfer of heatbetween the fluid and the conduit walls and consequently to the fln arrangement Ii of the heat exchanger. The cap members I: of conduits ii have an elongated portion 25 which is flattened to correspond to the flattened conduits II and this portion" fits over and is secured to the ends 23 of the conduits H (see Figs. 3 and 4). The ends of the elongated portions 23 of cap memhers I! are flaredoutwardly as at 21 adjacent the exclmnger llandtheseflangesaresecuredtothe end portions of the fin arrangement It.

The fin arrangement It of the heat exchanger dhclosed comprises a plurality of corrugated or folded metal strips generaly represented by the reference character 3i. There is a corrugated strip 3| interpowd between each of the superimposed-conduits II and it will be noted that each corrmated strip provides a plurality of relatively tall thin s through the exchanger Ill for the flow of air or other cooling fluid therethrough. The blank strip of metalfrom which a corrugated fin element 3i is formed is disclosed at 32 inl"lg.7. Theblank32isflrstpunchedoutas at 33 to provide a plurality of spaced apart elongated apertures or openings.

The material adiacent the lengthwise opposed walls 34 of the openings formed by the punched out portions 33 are then bent in opposite directions to one anotherasshownatfl and" inFig. 7 to provide legs or flanges extending at right angles to the extension of the strip 32. Alternate apertures in the blank strip 32 have the opposed walls thereof bent in opposite directions to the walls of adjacent apertures as disclosed in Fig. 8 of the drawings for a purpose to be presently described. The punched and preformed thin metal strip 32 shown in Fig. 8 is then folded or bent on lines passing through the center of an extending parallel with the extension of each aperture formed in strip 32 to produce a length of corrugated strip form 3|, a fragmentary portion of which is shown in Fig. 9 of the drawings. By referring to Fig. 9 it will be seen that the folding operation performed on the preformed fiat strip 32 causes the strip to assume a rig-sag form with the legs or flanges 3| and 33 thereof extending in the same direction and disposed closely adjacent one another. It will also be observed that the material between the ends of the apertures in blank 32 and the lengthwise edges of the blank extend beyond the end walls ofthe apertures as at31 to provide the corrugated structure II with raised portions on each side of a flat substantially continuom surface formed by the legs or flanges 35 and 33. The flat substantially continuous surfaces formed by the legs 35 and 3t inwardly ofthe extensions 31 are adapted to be placed in abutting relation with and secured to the flattenedsurface II of conduits ll.

In assembling the parts of the exchanger described a corrugated fln strip element 3| is placed upon a plate l1 and a conduit II is. then placed upon the fin element 3| with the flattened wall 3i thereof in intimate contact with the substantially continuous flat surface of the fin formed by the legs 33 and 3'. Another fin element or structure 3| is then placed over the conduit ll and the superimposing operations described are contimied until a heat exchanger of a predetermined size is assembled. The cap members I2 I with the conduits l3 secured thereto are then asof this invention in order to permit the substantially continuous flat portions formed by legs 35 and 36 to abut against the flattened portions 2| of the conduits. The extending portions 31 on fin members 3i are of sufilcient length to interfere with the extending portions 31 on other superimposed fln members 3i during the assembly operation. The extending portions 31 of members 3| which straddle the conduits ii are therefore telescoped together so as to be disposed in contacting relation as shown in Fig. 3. The smooth rounded end portions of the extensions 31 permits the telescoping or interlocking thereof to be readily carried out during the operation of assembling parts of the structure together. This telescoping or interlocking relation of the extensions 31 with one another thus provides a continuous contacting fin surface across the plurality of spaced apart conduits ii on each side of the exchanger. This arrangement provides a heat exchanger or condenser structure wherein the temperature gradient between certain portions-and relative to other portions thereof is greatly reduced to increase the efficiency of the structure. It is obvious that the fin elements 3| afford a maximum amount of heat transfer fin surface for the exchanger l0 and provide a plurality of narrow air passages through the exchanger to thus cause substantially all air circulated through the exchanger to contact either the fins or the closed fluid conduits there of or both. After assembling all of the parts of the exchanger structure it in the manner described these plurality of parts may be secured or bonded together in any conventional manner well-known to those skilled in the art and now practiced in the manufacture of such devices. For example, the various assembled parts of the structure Ill may be brazed together with the aid of copper brazing material in a hydrogen furnace by inserting the structure therein or by passing same therethrough. This brazing of the structure will seal the plurality of fluid conduit connections and will provide a metal-to-m'etal contact of the fin elements 3i with one another and with the conduits, II. The brazing of the structure will also bond the leg portions 35 and 38 of the fin elements 3i to the flat lengthwise extending portion of the plate l1 to thereby provide a unitary heat exchanger of increased structural strength.

Referring now to Figs. 5 and 6 of the drawings it will be noted that I have disclosed a modified closed conduit structure for the heat exchanger iii. In this modified structure a pair of metal strips II and 42 having their edges bent over to provide legs are placed together in opposed relation upon a corrugated strip 45. This strip is constructed or formed in a fashion similar to the corrugated strip 22 to provide, when brazed within strips ti and 42, a closed fluid conduit 36. Since the edges 43 and 44 of metal strips II and 42 are bent or disposed at right angles to the fiat longitudinally extending portions thereof a-plug or the like element 41 must be placed between the elongated portion 25 of the cap members l2 at the point where the conduit 46 is secured to the cap members. This plug 41 closes the space between the straight sided conduit 4B and the semi-cylindrical inner surface of the portion 25 of cap members I2.

From the foregoing it will be seen that I have provided an improved heat exchanger such as a condenser for a refrigerating system and that the improved construction materially increases the e'tllciency of such devices and provides a device of increased structural strength. By increasing the efilciency of a heat exchanger by incorporating therein the maximum amount of fin surface such structures can be made small and compact and a tinuous contacting fin surface extending entirely across both sides of the exchanger and thereby decreases the temperature gradient between portions of the exchanger. It is thus seen that the increased eillciency of my improved heat exchanger'is due partly to the placing of a maximum amount of fin surface extending across the sides of the structure. The improved heat exchanger is simple in construction and the methods of assembling and manufacturing the same can be carried out at low cost.

While the form of embodiment ofthe invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: 1. A unitary heat exchanger comprising in combination, a closed fluid conveying conduit having a plurality of spaced apart portions, an element interposed between each of the spaced apart portions of said conduit, each of said elements comprising a single strip 01 metal bent or folded in contact therewith, each of said elements being apertured inwardly of an edge portion thereof at the point of said bends or folds to position an end portion of said fins in straddlingrelation to said conduit portions, and the straddling end portions of said fins of one element being telescoped a substantial distance into the straddling end portions of another of said elements to provide an extended contacting surface. between the fins along at least one side of said heat exchanger.

2. A heat exchanger including a closed fluid conveying conduit having a pair of elements associated therewith, each of said elements comprising a strip of metal folded back and forth to provide a plurality of fins extending laterally from said conduit and disposed in intimate thermal contact therewith, each of said elements being apertured inwardly of an edge portion thereof at the point of said folds to position an end portion of said fins in straddling relation to said conduit, and the straddling end portions of said fins of one element being telescoped a substantial distance into the straddling end portions of the other of said elements to provide an extended contacting surface between the fins along a side of said conduit.

HARRY 1". SMITH.

Images