US2212912A - Refrigerant evaporator - Google Patents

Description

Aug.27,194o. Mmmm ,2,212,912

REFRIGERANT EvAPoRAToR original Filed June 15, 1955 4 sheets-sheet 1 INVENTOR.

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ATTORNEYS Ag- 27, 1940. M. F. BOOTH REFRIGERANT EvAPoRAToR Original Filed June l5, 1935 4 Sheets-Sheet 2` Q E@ M `ATTORNEY Aug. 27, 1940. M F, BOOTH 2,212,912-

REFRIGERANT EVAPOR'ATOR origial Filed June 15. 1955 4 sheets-sheet s 1 INVENTOR /Worr/s 77.500775 ATnnwmYs Aug. 27, 1940.

REFRIGERANT EVAPRATOR original Filed June 15. 1935 4 sheets-sheet 4 ATTORNEYS Patented Aug. 21, 1940 UNlTE-DPSTATES 4PA'rizN'r v4v`oFF-ica I RR f Application June 15, 1935, SerialvNo. 26,725

Renewed October 6, 1939 so claims. (0162-126) This invention relates to refrigerant evaporators, and has to do particularly with novel and eilicient refrigerant distributing and heat exchange means fabricated in such a manner to insure a minimum productive cost.

Evaporators of the copper coil type, particularly those having a liquid and gas header and independent walls depending therefrom for defining a sharp freezing chamber, have been generally replaced in the art by evaporators the sharp freezing distributing walls of which are formed of inner and outer sheet metal walls we1ded together and formed as a part of or connected tothe header. Many modifications have embodied different types and arrangements of corrugations and header constructions, together with methods of fabricating and welding.

'It is the object of the present invention to provide an evaporator, the main or sharp freezing portion of which is formed of integral extruded metal, the refrigerant passageways, the walls defining the sharp freezing section, and the heat conducting finsY all being formed in' the Vsame integral extruded sheet of metal. In the preferred method, the circulating part of the evaporator forming a sharp freezing section is initially extruded in a fiat sheet and may then be bent to desired shape or left flat and the ends of the passageways connected to a header or headers to complete the evaporator.

Further features of the `invention havel 'to 'do 'with an evaporator formed of extruded metal, .which is preferably a non-ferrous metal, such, for instance, as aluminum, copper or brass, the

85 extruded metal sheet being refined by the extrusion step whereby such metals as aluminum, which could not be used in a cast form because of porosity, can now be safely used because of refining and compacting of the grains of the t0 metal. The extrusion or refining step also makes the final sheet relatively easy to bend. Flat extruded metal sheets can be thus cut to various lengths desired for use for diffrent sizes and shapes of sharp freezing sections.

Other features of the invention have to do with means and 'the manner of connecting the ends of the extruded section to complete the evaporator. Still other features have to do with details of structure and various modifications to B0 which the invention adapts itself, as more clearly set forth in the specification and claims.

In the drawings:

Fig. 1 is a fragmentary 'plan view of a portion of extruded section used in forming a sharp Il freezing section of an evaporator,

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1 and illustrating one modified manner of' forming the fins as desired. Fig. 3 is an elevation of one form of `evaporator unit in which thel side walls and bottom are formed of the extruded section.

Fig. 4 is `an elevation of an evaporator in which the extruded section forms `the greater part of the evaporator and the ends are connected together bye. small header. 10

Fig. 5 is a view similar to Fig. 4 except showing the adaptation of the extruded section to an evaporator with top and bottom headers.

Figs, 6, 7, and 8 represent sectional plan and elevation views of one marmer of forming and 15 connecting the ends of the extruded section to the header.

Figs. 9 and 9a illustrate Ia further modified manner of connecting the section ends to theheader utilizing small tube lengths i'or connecting 20 a butt Weld.

Figs. 10, 11 and 12 illustrate sectional, end and plan views of a further modification wherein the ends of the passageways of the extruded sections are ared. 25

Figs. 13, 14 and l5 present a further modification'in which the ends of the extruded section are left ush in welding the same to the header.

Figs. 16, 17 and 18 represent still further modifications 'in the manner of connecting the ex- 30 truded section to the header.

Fig. `19 is a'fragmentary perspective view i1- lustrating a further modified manner of con-. necting the extruded section to the header wherein the header sections are fabricated anged to 35 the header being initially in the form of a flat sheet and then shaped and Welded.

Fig. 25 illustrates in solid and dotted lines the manner of connecting the end section to the fiat sheet and then bending to shape.

Figs. 26, 27 and 28 illustrate the adaptation of the extruded section to a dry system evaporator wherein the ends of the extruded section are stepped over to form a continuous passageway.

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Figs. 29, 30 and 31 illustrate different methods of connecting one end of the extruded section to a single header or manifold.

Fig. 32 is a fragmentary view illustrating the manner of inserting a header cap in headers of the general type shown in Fig. 19.

Fig. 33 is a fragmentary view, partly in section.

of a modified shape of header construction and manner of welding the same to the extruded section.

The most important part of a refrigerant evaporator is the sharp freezing section or the portion of the evaporator which effects circulation of the refrigerant. In evaporators having a header and a plurality of separate coils depending therefrom, use is made of heat conducting fins connecting the respective coils. However, efficient heat transfer here is reduced to a minimum because of the break in the metal between the coil and the heat conducting fins. This problem is in a way solved by sheet metal evaporators in that the connecting fins between the corrugations are formed integral with the corrugations, but here again we have inner and outer sheet metal parts `forming the sharp freezing chamber and here again we have the question of the break between the metal forming the inner and outer part of the shells.

In the present invention the entire sharp freezing section of the evaporator is extruded. In Figs. 1 and 2 I have shown one form of extruded section which may be utilized for forming evaporators. This extruded section may be generally designated 2 and includes a plurality of conduits 3 separated by web portions 4. Such web portions 4 may be provided with fins such as at 5 which obviously may be of any number and shape. The walls forming the conduits 3 may be also provided with extruded fins 6 which, as shown at the left of Fig. 2, may extend inside of the conduit to greatly increase the surface area exposed to the refrigerant within the conduit. The extruded section, as shown in Fig. 2 is formed in two parts and welded together as at 'I but it will be understood that this is merely a question of the size of the dies for performing the extruding operation. With large size dies, any length of evaporator may be formed with a single extrusion step. It will thus be seen that the metal going to form the sharp freezing p section, Whether it be the web, the conduits, or

ns is all formed in one integral piece, with the result that conductivity in all directions or in any particular direction desired is 100% efiicient, as far as the particular metal used is concerned.

Due to limitation of dies,- I have found that aluminum is very well suited for use in extruded evaporator sections, although it will be understood that any other metals may be used, limited only by available dies for accomplishing the extrusion step. AluminumA becomes important because when heated to extrusion temperature and placed under high extrusion pressure, the texture of the metal is greatly refined with the result that the extruded section of aluminum is substantially equivalent to standard sheet aluminum. Because of the refined nature oi' aluminum after the extrusion step, all question of leakage of the volatile refrigerant through the aluminlun is eliminated. Heretofore, leakage has been a. very kserious drawback because of the porosity of cast aluminum.

to the size and shape of the particular sharp freezing chamber desired. For instance, in Fig. 3 I have shown the 'sharp freezing section 2 as being bent into a U shape and terminating in spaced headers 8 and 9. In Fig. 4 the extruded section 2 is bent to form substantially the entire top of the sharp freezing chamber as well as the bottom and sides', a single header I0 being used as the connecting means for the ends of the extruded sections. In Fig. 5 the extruded sections 2 and 2a are shown connected to and connected together by top and bottom headers II and I2. The sharp freezing section may also be flat or disk shaped with a header secured at each end.

In Figs. 6 to 25 I have illustrated various ways of attaching the extruded section 2 to a header member I3. In Figs. 6, 7 and 8 one method is illust-rated where the Web part 4 of the fin section is cut back as at I4 which permits the conduits 3 to project into the header and permit of av weld as at I5. In Fig. 9 the n section is left intact and small nipples I6 used as a connecting means between the header and the conduits of the 1in section so as to permit a butt weld as at I'I. In Figs. 10, 11 and 12 the web portion 4 of the extruded section is cut back similar to Fig. 7, but the ends of the conduits are ared as at I8. This makes possible a still different type of weld.

In Figs. 13 to 15 the end of the section is flared as at I9 so as to flt the circumferential shape of the header. The above various ways of connecting the extruded section to the header are shown in detail to illustrate a variety of ways in which this connection is possible and to also indicate that this may be accomplished in many other ways within the skill of the fabricator and Welder.

Going further into details oi' connection between the section and the header, Fig. 16 illustrates a butt weld method of joining the two obtained by heat and pressure. Fig. 17 illustrates a further modification in which the extruded portion of the header I3 extends within the conduit 3 of the extruded section, the weld taking place at 2l and being in the form of a wavy outline following the contour of the* extruded section.

Fig. 18 is similar to Fig. 6 except here is illustrated the manner of connecting the ends of the tubular sections to the header by casting the same with a metal of lower melting point.

In Fig. 19 I have illustrated a method of connecting the extruded section to the header wherein the header is formed in two halves 22 and 23, the half 22 being fabricated as at 24 to fit over the conduits 3. Assembly and partial sealing are obtained by spot welding as at 25 and complete sealing obtained by gas welding along the edge 26. It will be understood here that the header I3 would be made of a stamping. In Figs. 20, 21 and 22, I have illustrated methods of connecting together adjacent conduits 3 in the extruded section 2, U-tubes 21' being connected into the adjacent conduits 3 and welded as at 28. In Figs. 21 and 22 I have shown the use of stamped return bends formed in sheet 29 which cooperates with a sheet 30. In this case the ends of the conduits 3 will be extended as at 3a to fit within the stamped portions of the return bends, the two stamped portions 29 and 30 being welded together at the various points 3| and the edges `32 of the section and the stamped portions 2l and 30.

In Figs. 23, 24 and 25 I have illustrated another method of header and extruded section connection wherein the conduit ends of the extruded section areprojected through suitable apertures in flat sheet 33 and the ends of the conduits fla'red over as at 34 and welded at 35.

dotted lines and welded at 31 Vto complete the header.

In Figs. 26 to 28 I have illustrated the use of my extruded section as applied'to ,dry -system evaporators and the like. In this case the extruded section 2 is extruded for .the-l length required and side Walls cut away as aty 33 andtheends cut on an angle as at 39 so that when the extruded section is bent to shapethe end of one conduit 3b will align with the end of adjacent locked into an extruded lock joint 44 of the extruded portion of the header. In Figs. 30` and 31 the ends of the conduits 3 are inserted through the aperture 46 formed in a cast header 41 and a mechanically at joint formed at 48. 'I'he header is tapped as at 49 to receive a plug 50 for completing the sealing between the section and the header.

Fig. 32 illustrates one method of capping in,

a header of the type shown in Figs. 6 to 26, a cap being shown at 5| and welded to the header I3 at 52. Suitable inlet and outlet conduits 53 may be secured to and carried by the cap 5I. It will' be understood that a similar but imperforate cap will be Weldedto the other end of' the header;

It will be understood that the header scetions may be formed of various metals. In some cases standard sheet metal tubing vmay be used or such headers may be extruded tubes of the diameter required and such extruded metal may be aluminum, copper, brass, etc. In headers of the type illustrated in Fig. 19 it will be understood that these may be sheet metal stampings or sheet aluminum or brass and the like. i

In Figs. 23 and 25 it will be obvious that the sheet 23 may be of ordinary sheet metal or sheet aluminum or other sheets of non-ferrous metal.

In Fig. 33 I have illustrated a modified manner of forming headers in U-type evaporators such as shown in Fig. 3. Inv this modification the conduits3 are extended to almost the end of the extruded section and flattened out as at 60. A plurality of apertures 6I may be formed -in the inner wall of the section and a header 62 of suitable shape and size welded to the flat inner wall of the section. It will be obvious that the header 62 vand the opposite ends of the section may be joined together as shown in Fig. 3

and provided with a suitable outlet.

It will thus be seen that I have provided a refrigerating unit. the circulating and sharp freezing portion of which is formed by the simple step of extrusion; the conduits are formed integrally with the webs, fins, etc., without the necessity of welding ofA any kind. Finish enameling is eliminated and what little finish might be necessary is inexpensive and quickly applied. The extruded section may be easily bent to shape without the necessity of heavy The flat' sheet 33 may then be bent to shape as shown at 36 in -stamping and bending dies. Inasmuch as all parts of the extruded section are integral, there is no tendency of one part to break away from another part because of internal pressure as in the case of welded together sheet metal parts.

What I claim is:

1. As a new article of manufacture, a refrig-A erant evaporator having a header, and a one piece wall structure attached thereto and formed. in.- tegrally of a sheet of. non-ferrous extruded metal and a plurality of thin walled *conduits and connecting webs integrally formed in saidv wall struc-v ture, said' conduits and webs' y beingf so arranged as to permit easy bending of said vone piecerex-` truded section. A

2. As a new article of manufacture, afrefrigerant evaporator having walll structure formed integrally of a single, sheet of nonferrous extruded metal and shaped and bent to form a plurality of `wa1ls of a sharp'freezing chamber, and a plurality of spaced thin walled conduits and connecting webs formed in said wall structure.

3. I'he method of forming a refrigerant evaporator which comprises forming a header unit of sheet metal-and a sharp freezing sectionof extruded metal', a plurality of thin walled conduits being formed in said sharp freezing sec-` tion of extruded metal, bending said extruded section to the shape desired to form the walls of the sharp freezing chamber and connecting the ends of the conduits and at least one of the ends of the extruded section to the header.

4. The method of forming a refrigerant evaporator whichcomprises forming a header unit of sheet metal and a sharp freezing section of extruded metal of relatively thin cross section, a plurality of thin walled conduits of circular cross section'being formed in said sharp freezing section-of extruded metal, bending said extruded section to the shape desired to form the walls of the sharp freezing chamber and then connecting and 'sliapedto'forr'n a sharp freezing chamber,`

the ends of the conduits and at least one of the .leak proof aga-inst refrigerant, and then bending said extruded aluminum wall tothe shape of the sharp freezing section.

6. An evaporator unit of the class described comprising a header portion and al uid circulating portion, said circulating portion including angularly. positioned walls formed of extruded metal having a plurality of -conduits formed therein at right angles to the longitudinal axis of and connected and leading into the header portion.

7. An evaporator unit of the class described comprising a header portion and a uid circulating portion, said circulating portion being formed of extruded metal. having a plurality of conduits therein, and fins formed therein and thereon, and connected and leading into the header portion.

`8. A refrigerant evaporator comprising an integral unit composed of Walls and conduits of extruded metal of relatively thin wall section, and header means connecting said conduits, a portion of said walls being flat on one side and said conduits projecting from the opposite face thereof.

9. As a new article of manufacture, a domestic refrigerator evaporator having freezing walls formed completely from a single piece of extruded metal and including a, conduit'formed in the extruded metal, said conduit being of spiral form from an inlet to an outlet to dene the top, bottom and side walls of an evaporator, and web portions filling in the space between adjacent spirals of the conduit to form the evaporator shell.

10. As a new article of manufacture, a domestic refrigerator evaporator formed from extruded metal, said metal being formed to provide a conduit portion and web portions, said conduit portion being so shaped as to form a continuous conduit and the web portions between adjacent portions of the conduit defining the walls of the evaporator.

11. As a new article of manufacture, a refrigerant evaporator having a header member, and a sharp freezing wall structure formed of nonferrous extruded metal in the general form of a sheet having a relatively thin base, and a plup rality of spaced thin walled conduits circular in cross section formed in said extruded metal and positioned to one side of said base, said sheet having a plurality of walls bent in the shape of a sharp freezing chamber.

12. A heat exchange unit comprising a one piece heat transfer section formed of extruded metal, a plurality of conduits integrally formed in said section and forming fluid circulating means, and extruded fins extending laterally from the wall of one or more of said conduits to enhance the rate of transfer of heat units through said wall or walls.

13. An evaporator comprising a header and a wall structure rigid therewith; said wall structure comprising a sheet of metal extruded to form a plate having a plane face on one side and a plurality of parallel ribs projecting from the opposite face. and each having a longitudinal passage therethrough, said plate being bent to form a chamber for receiving goods to be refrigerated and each of said passages communicating with said header.

14. The method of forming at least a portion of a sharp freezing section of a refrigerant evaporator, which comprises extruding metal to simultaneously form one or more thin walled conduits and a web portion extending from said conduit or conduits, and bending said extruded section to the shape desired to form the walls of the sharp freezing chamber whereby the nished freezing section includes a plurality of angularly spaced walls having parallel Aconduits and web sections connecting the conduits, said web sections dening the internal surface of the evaporator.

15. As a new article of manufacture, a. refrig- Y erant evaporator having a sharp freezing portion formed of extruded metal shaped and bent to form a plurality lof walls of a sharp freezing chamber, said extruded metal forming the walls comprising parallel thin walled conduits and connecting webs therebetween.

16. As a new article of manufacture, a refrigerant evaporator having a sharp freezing portion formed of extruded metal shaped and bent to form a plurality of wallsof a sharp freezing chamber, said extruded metal forming the walls comprising integral thin walled conduits and web portions, said conduits being parallel and said web portions defining the inner walls of the sharp freezing section.

. wall section in the form of a thin walled conduit 17. A freezing section for a refrigerant evaporator comprising wall structure formed of extruded metal, a portion of said wall structure including spaced thin walled conduits and web portions, said conduits and web portions being 5 arranged to form a substantially solid wall with spaced conduits and connecting web portions, and conduits connecting the ends of two adjacent conduits of the wall structure and extending past the web portions positioned between the conduits. 1o

18. A freezing section for refrigerant evaporators comprising a wall structure formed of extruded metal, said wall structure including extruded conduits and extruded web portions, said web portions cooperating to form a solid wall, a portion of the web portion adjacent one or more conduits being removed whereby the conduit or conduits is left in tubular cross sectional form and protrudes past the solid wall formed by the web portion or portions.

19. A freezingA section for refrigerant evaporators comprising a wall structure formed of extruded metal, said wall structure including extruded conduits having iliat surfaces on one side and extruded web portions having one surface registering with the fiat surface of the conduits, said web portions being so arranged as to form with the fiat surface of the conduits a plate face on one side of the wall structure, the conduits forming projections onthe other side of the wall structure.

20. A freezing section for refrigerant evaporators comprising a wall structure formed of extruded metal, said wall structure including extruded conduits having flat surfaces on one side 3" and extruded web portions having one surface registering with the flat surface of the. conduits, said web portions being so arranged as to form with the flat surface of the conduits a plate face on one side of the wall structure, the conduits forming projections on the other side of the wall structure, said conduits being parallel, and conduits for connecting the ends of the adjacent parallel conduits and extending past the wall structure defined by the web portions.

21. Method of forming at least a portion of the heat exchange section of a heat exchange unit which comprises extruding such section of aluminum, simultaneously extruding an aluminum and a web portion on either side thereof, said extrusion step rening the aluminum to make the same leak proof, and then bending said extruded aluminum wall section to form angularly positioned walls of the heat exchange section.

22. A heat exchange member comprising an extruded unit having walls formed of web separated conduits of extruded metal and means for connecting said conduits into a circulatory system, said conduits and webs being formed of relatively thin wall sections `stiffened by bending.

23. A heat exchange unit having a wall structure formed of extruded aluminum, said wall structure including a thin walled conduit and a thin web portion on at least one side thereof, said wall structure being bent to form bottom and side walls and being arranged to form a continuous conduit, portions of which are parallel.

24. A heat exchange unit comprising a, heat transfer wall section formed at least in part of extruded metal, said wall section including a plate portion and a thin walled-fluid conducting conduit of extruded metal in direct heat conducting relation with said plate portion.

25. A heat exchange unit comprising a heat y forming the walls comprising a continuous thin walled conduit having parallel portions'and connecting webs between the parallel portions.

27. A heat exchange unit having a transfer section formed of extruded aluminum, said section including a thin walled conduit and extruded thin web portions projecting laterally therefrom, said extruded conduit being bent and forming the heat transfer section so that portions of said conduit are parallel.

28. A heatexohange unit having a transfer section formed of extruded aluminum, said section including a thin walled conduit and extruded thin'web portions projecting outwardly and inwardly from said wall, said extruded conduit being bent and forming the heat transfer section so that portions of said conduit are parallel.

29. A heat transfer unit having the heat ex. change section thereof formed of extrudedmetal and including a thin `walled extruded conduit l0 having ns extending outwardly and inwardly from the wall'thereof.

30. A heat transfer unit having a heat transfer section thereof formed of extruded metal, said section including a plurality of conduits termiu nating in a relatively flat surface, a header portion connected to .said relatively flat surface and one or more openings in said flat surface for oonnecting said conduits to said header portion.

MORRIS F. BOOTH.

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