US2433951A - Refrigerator evaporator - Google Patents

Description

` Jan. 6, 1943.v

C. E. HICKMAN REFRIGERATOR EVAPORATOR Filed May 18, 1946 :s sheets-sheet 1 .lim

Array/vir Jam 6 1948- c. E. HICKMAN REFRIGERATOR EvAPoRAToR Filed May 18, 1946 3 Sheets-Sheet 2 INVENToR. FM4/Pz s Mc/mmm Mazzi;

Jan l6 1948' c. E, HICKMAN REFRIGERATOR EVAPORATOR lFiled May 18, 1946 3 Sheets-Sheet 3 INVENTOR.

m M m M fr.. m W C ATTORNEY Patented Jan. 6, 1948 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to an improved evaporator which is particularly adapted for use in household refrigerators, although certain of its features may be useful in evaporators of other types.

The evaporator of the present invention is mainly formed from extruded material as suggested in the prior patents to Ackerman, 1,969,813, issued August '7, 1934, and Booth, 2,212,912, issued August 27, 1940. The main body of the evaporator is formed from a sheet of material originally extruded With a plurality of spaced conduits formed therein, which sheet may be used in any preferred shape. The present invention relates particularly to header constructions that are of particular utility with this style of evaporator.

A feature of the invention resides in the use for the distributing header of a special extruded shape particularly adapted to permit simplified attachment by oven brazing.

Another feature is to be found in the construction of the accumulating header, which also is Well adapted to assembly by oven brazing.

While preferred forms of the invention are disclosed herein by way of illustration, it should be understood that various changes may be made in the structure without departing from the spirit and scope of the claims.

In the drawings:

Fig. 1 is a perspective view of an evaporator embodying the invention.

Fig- 2 is a perspective of the extruded shape from which the body of the evaporator is formed.

Fig. 3 is an exploded fragmentary view illustrating the construction and attachment of the distributing header.

Fig. 4 is a fragmentaryyiew, partly in crosssection, illustrating further the construction of the distributing header and associated passages.

Fig. 5 is a cross-section taken 0n line 5-5 of Fig. 4.

Fig. 6 is a fragmentary perspective partly broken away showing the construction of the accumulating header.

Fig. '7 is a view similar to Fig. 5 illustrating possible modifications.

Fig. 8 is a view similar to Fig. 5 but illustrating additional variations in the structure.

Fig. 9 is a fragmentary perspective showing certain modifications as applied to an accumulating header.

Fig. 10 is a cross-section taken on line Ill-I0 of Fig. 9.

Fig. 11 is an end elevation of a U-shaped `evaporator with a distributing header located at the bottom of the U, and an accumulating header located at the upper end of each side of the U.

Fig. 12 is an exploded fragmentary perspective illustrating the construction of the distributing header of Fig. 9.

The present application which is led to replace my prior-led application Ser. No. 576,828 now abandoned, is a duplicate of the prior-liled application except that Figs. 9 and 10 have been added. The present application is therefore a continuation in-part of said abandoned Ser. No. 576,828.

Referring to the drawings more particularly, Figs. l to 6 inclusive illustrate a preferred form of the invention, Which is designed for use in a household refrigerator. For purposes of illustration the dimensions given herein are presently preferred for use in an evaporator for a household refrigerator of average size, namely 7 to 8 cu. ft. capacity. The evaporator, which is shown in a general view in Fig. 1, comprises a main body portion I0, a distributing header II, and an accumulating header I 2.

A primary step in the manufacture of the evaporator is to extrude a strip or plate of material having the shape illustrated in Fig. 2. This shape as illustratedrhas a fiat face I3 and longitudinal ribs I4 projecting from the opposite face of the sheet. These ribs I4 are joined together by the relatively thin Webs I5 and are contoured so as to give this face of the sheet a smooth and pleasing appearance. The longitudinal ribs I4 are pierced by conduits I6 which conduct the refrigerating uid in a manner which will be subsequently explained. One edge of the extruded shape carries a finishing bead Il while the opposite edge carries bead I8 which is somewhat heavier than the bead II. The shape illustrated in Fig. 2 is extruded in a long strip from any suitablematerial, such as commercially pure aluminum. It may be of suitable widths for particular designs and it may carry as many of the conduits I6 as considered desirable.

The conduits IB are given a fiat rectangular shape since this shape has the advantages ofre- K ducing the height of the longitudinal ribs I4 and truded shape 24 inches long would be cut off for the evaporator illustrated in Fig. 1.

A particular feature of the invention resides in the construction of the distributing header II and its attachment to the main body II). The

header II is formed from an extruded section having a cross-sectional shape which, as shown in Figs. 3 and 5, includes a tubular body I9 which has a flat face 20 adapted to engage a flat end surface of the main body IIJ, and which has an offset flange 2i which carries a flat face adapted to engage the flat surface I3 of the main body IIB. Along the line of junction between the offset flange 2i and the body I9, a groove 22 is formed which is adapted to receive a piecevof braZing wire. The outer shape of the extrusion for the distributing header is contoured to accommodate the groove 22, preferably by a projectingl rib 23. This shape for the distributing header II is also preferably extruded from commercially pure aluminurn.

Prior to the assembly of distributing header II with the main body I3 a plurality of orifices 24 are drilled through the flat face 20 so as to communicate with the cylindrical passage 25 of the body I9. The orifices 24 are located so that when the distributing header II is assembled with the mainbody ID, as shown in Fig, 5, each of the oriiices 24 registers with one of the longitudinal conduits IS as clearly shown in Fig. 4. The orifices 2 4 are preferably from 1/8 in. to in. in diameter, the latter size being the smallest that can be used in the present construction Without danger of the orifice becoming filled with brazing material by capillary action during the subsequent brazing operation. The cylindrical passage 25 is approximately Tse in. in diameter. This diameter should be slightly larger than the combined areas of the orifices 24 in order to maintain proper liquid supply to these orifices, but it should be kept as small as possible in order to minimize evaporation of the liquid refrigerant before it reaches the oriiices, By thus insuring that substantially no gas passes through the orices 24 a uniform distribution of the refrigerant to the conduits IE is assured.

The process o-f attaching the distributing header -I I to the main body I starts with filling groove 2,2 with a suitable brazing material which has a slightly lower melting point than the melting point of the commercially pure aluminum used for parts Il) and I I. This brazing material, which may be an alloy of aluminum containing a small percentage of silicon, may be introduced into groove 22 in the shape of wire 26. The distributing header II Vis then assembled on main body II) to the position illustrated in Figs. 4 and 5, in which the at face 25 of distributing header II engages one of the at end surfaces of main body I and the inner fiat face of the offset flange 2! engages the fiat surface I3 of main body III. The parts may be temporarily held in this assembled relation in any preferred manner, as by tacking them together with several 'spot wel-ds. A closure plug 21 is inserted 'in one end of the cylindrical passage 25, while the liquid inlet line 28 is inserted in the other end, plug l21 and line 28 both being suitably supplied with brazing material. Subsequently, after other parts have been put into place for brazing, the complete assembly is ovenbrazed at a temperature which causes the brazing material to melt and run by capillary action between the contacting surfaces, producing a strong and leak-proof joint lat all area of contact.

Another feature of the invention resides in the construction of the accumulating header I2 and its attachment to the main body II] as illustrated in Fig. 6. The accumulating header is formed from a round tube approximately 1%. in. in diameter formed of commercially pure aluminum. Prior to the assembly of accumulator I2 with the evaporator, the appropriate end of main body I0 is prepared as illustrated in Fig. 6. This preparation consists of cutting back the Webs I5 for a short distance between the ribs I4 so as to leave the ends of these ribs projecting as short tubular extensions from the main body I0. These extensions will have the same shape they had when they were a part of the main body I0, that is, they will have a substantially D-shape with a flat face corresponding t0 the flat surface I3 of the main body, and with a rounded upper face correspond- -ing to the contoured surface of the main body.

The tube which is to form the accumulating header I2 is prepared for assembly by forming in its wall a series of D-shaped holes corresponding in shape with the projecting ends of ribs I4 and spaced so as to exactly register with these projecting ends. The accumulating header is then assembled with the main body Ill by inserting the projecting ends of ribs Id in the holes that have been formed in header I2 and brazing compound is suitably paced so that during the subsequent brazing voperation all the areas of contact between the accumulating header I2 and the main `body I3 are covered by brazing compound, forming a fluid-tight seal. One end of the header I2 is closed by brazlng within it a closure cap 29 whilei-n the other end is brazed a cap 30 apertured to receive the gas return line 3|.

In order to provide a liquid trap within the accumulating header a partition in the form of a cup-shaped disk 32 is brazed Within the header near its outlet end. This disk is formed with a small aperture 33 which is positioned so as to be at the to-p of the header when the evaporator is in its iinal installed position. The construction of the header is such that when the refrigerating apparatus is on the off cycle, the conduits I6 may be comp-etely hooded and there may be a small surplus of liquid refrigerant in the accumulator lf2, but at the same time the trap provided by disk 32 insures that none of the liquid will be drawn from the header into the return line 3I when the compressor begins to operate. This arrangement increases eiciency and promotes uniformity'of vfrosting of the evaporator.

:It should be 'understood of course that while the 'construction just described for the accumulating header lI2 is aipresently preferred construction, this header may be formed and attached in any suitable manner, vas for example, in the manner described in connection with the distributing header II.

In order to `form the type of evaporator illustrated in Fig. 1, the sheet of extruded material forming the :mai-n `body I0 is bent up into U-shape with lthe `ribs I4 on the outside, as clearly shown in Fig. 1. The liquid line 28, which conducts liquid refrigerant to the distributing header I I, may pass along the under side of a shelf 34 as shown. After vall of the parts have been assembled to the position illustrated in Fig. 1 and the brazing compound described above has beenI applied Wherever necessary, the assembly can be oVen-brazed in a manner well known in the art. This brazing process joins all of the aluminum parts together so that the completed evaporator is an integral, substantially homogeneous mass of aluminum 5 with no joints or other discontinuities to interfere with eilicient heat flow throughout the mass.

In the completed evaporator, liquid refrigerant flows from the liquid line 28 to the distributing header I I, whence it is fed through the orifices 24 into the conduits I6 of the main body I0 of the evaporator. The gas produced by evaporation of the liquid refrigerant collects in the accumulating header I2 and is drawn oil by the compressor through the return line 3|. The compressor and other parts of the refrigerating mechanism, being conventional, are not illustrated, and of course any other suitable means for circulating liquid and gaseous refrigerant may be used.

The inlet line 28 and the return line 3| project from the rear of the evaporator, which carries the lighter finishing bead Il. The heavier bead I8 is at the'front of the evaporator where it may be used to attach a door if desired.

While the improvements of the present invention have been illustrated in connection with a U-shaped evaporator it will be clear to those skilled in the art that the evaporator can be given other shapes suitable for particular installations.

Various modifications of the structure above described are within the scope of the invention. For example, Fig. 7 illustrates a variation in the construction of the distributing header. In this case the groove 22a for the brazing material is formed in the face of distributing header IIa which contacts the end face of the main body I and the oflset flange Zia extends straight down parallel to the ilat face I3 of body I0 thereby avoiding the presence of the projecting rib 23. This alternate construction shown in Fig. 7 thus eliminates the presence of the projecting rib 23 although it requires some additional space in the main body of the distributing header to accommodate the brazing material.

Fig. 8 shows how a construction similar to that illustrated in Figs. and 7 can be utilized in other types of evaporators. In this construction the strip 35 has two conduits 36 and 31 formed therein, the conduit 36 being in communication with the conduits of a main body 38 similar in construction to the main body Il] illustrated in Figs. 1 to 5 inclusive, while the opposite ends of the conduits of body 38 are in communication with the conduit 37 of the strip 35. Strip 35 carries a flange 39 for attachment to one end of body 38 and a ilange 4i] for attachment to the other end of body 38. By blocking off the conduits 36 and 31 at suitable points this construcion can be utilized for a continuous-tube type of evaporator.

Several other permissible variations are illustrated in Figs. 9 and 10, which show an accumulating header I2b. In this form the header is extruded as a shape having the cross-section shown in Fig. in which the cylindrical body carries an oiset flange 2| b, which serves the same purpose as flange 2| of Fig. 5. However, in the structure of Figs. 9 and 10, the groove for the brazing material is formed on the outside of the flange, as by the rib 4|. A plurality of holes 42 permit the brazing material to pass to the contacting surfaces of the ilange 2| and body IIJ, thus providing a good joint without the opening at the end of the header which results from using a groove on the inside of the joint, such as the groove 22 of Fig. 3.

When the headers are extruded it is of course 'possible to extrude them with ilanges of any desired shape to serve as brackets for attaching the evaporator in its proper place in the refrigerator 6 box. A flange of this nature is shown at 43 in Figs. 9 and 10.

In the accumulating header of Figs. 9 and 10, the liquid trap is formed by a horizontal baille 44, which extends across the cylindrical bore of the header body. The body carries ribs 45, 46 and the baille is a separate unperforated plate which is placed on ribs 45, 46 and is subsequently brazed in Place. The plate 44 is shorter than the main body of the header, and hence the gas which is formed can pass around the ends of the plate to the gas chamber above the plate. The suction line Sla is in communication with outlet open ing 41 which is at the top of the header and at about the middle thereof.

During operation of the evaporator, liquid refrigerant may rise into the lower part of the accumulating header, and it is desirable to provide as large a liquid chamber below baille 44 as possible. However, the area of the gas chamber above baille 44 should be large enough that the gas `will move at relatively low velocity, so that droplets of liquid refrigerant will not be entrained and carried into the suction line. To satisfy these requirements, the baille 44 is shown as located approximately two-thirds of the way up from the bottom of the bore of the accumulator, although this exact position is not critical.

A plurality of openings 48 is formed in the bottom wall of the header, each opening 46 being in register with a conduit I6 of the main evaporator body I6, This header may be brazed to one end of body I6 in the manner previously explained.

If desired, the baille 44 may be extruded as an integral part of the header, in which case, the ends of the baille must be cut away to permit gas to pass around its ends.

In the variation illustrated in Fig. 11, a distributing header '49 is located at the bottom of the evaporator and an accumulating header I2a is attached to the upper end of each side of the U. The construction of Fig. 10 is in most respects similar to that previously described in connection with Figs. 1 to 6 inclusive except for the shape of the distributing headerv and its connection to the main body Ia, these latter arrangements being shown in Fig, 12.

In this construction the header 49 is an aluminum tube which runs at right angles to the conduits I6 of the body I6, and a huid-tight connection is made between the tube 49 and each of the conduits I 6 by means of a spud 5D. This spud has a reduced lower end which ts closely in the hole 5| which communicates with passage I6, the shoulder 52 serving to keep the spud from extending too far into conduit I6 during assembly. A disc 53 of brazing compound is placed around the spud 5I] and the parts are then assembled, the spud having its reduced end projecting into conduit I6 and its large end projecting into the tube 49. Subsequent oven-brazing fuses these parts into a substantial and fluid-tight connection forming a passage between tube 49 and conduit I6. One end of the header 49 is of course closed in any preferred manner, and the liquid inlet line is connected to its other end,

By using one or more of the features described above, it is possible to construct an evaporator of simple and sturdy construction that will give long and eioient service, as will be understood by those familiar with the art of refrigeration.

I claim:

1. In an evaporator of the type in which the main body is formed by a unitary plate having 9.

'aasageai plurality of kconduits I.formed therein V:each end of each conduit being in communication with a header, the :improvement which comprises: a flat surface vextending across the width of said unitary plate, a header having Aa .flat face 4engaging said `iiat surface, said .nat surface and flat face lbeing b-razed together, the header having a groove 'adapted to hold brazing material prior to the brazing operation.

2. In an evaporator of the type in which the main bodyis formed by a unitary plate havingfa :plurality of conduits formed therein, one side of the .plate constituting-a first flat surface and the :opposite side having .projecting ribs which extend over the conduits, each end of eachconduit 'being in communication with a header, the improvement -which comprises: a header having va first at vface engaging said first flat surface of the 4unitary plate, ltheiunitary plate having a -sec- 'ond flat surfacewhich extends across the end :of the plate and .is disposed at right angles to :said lfirst lflat surface, the 'header 'having a second hat face engaging said second fiat surface, -said flat faces having brazed to said flat surfaces, `the header having a groove adapted to hold brazing material prior to the 'brazing operation,

3. In an evaporator of the type in which the main body is formed by a unitary plate having -a plurality Vof conduits formed therein, one side of the plate having a first lflat :surface and the opposite side having projecting ribs which extend over the conduits, each of said conduits hav- `ing one of its -ends in communication with a header, the improvement which comprises: the lunitary plate having a second nat surface which extends across the end of the plate, the header having an olf-set flange 'formed with a rst flat face which engages the first flat surface of the unitary plate, the header having a second at .face at right angles to the first flat face, the second flat face engaging the second flat surface of the unitary plate, said at faces being brazed to said flat surfaces.

4. The structure as setforth in claim Bin which the header has a groove lopening toward one of #said flat surfaces of the unitary plate, said groove 'being adapted to hold brazing material prior .to the brazing operation.

5. The structure as set forth in-lclaim 3 in which .the header has a groove on a side away from said flat faces and has a plurality 'of holes extending from said groove to one `of said flat faces.

'6. The-structure asset forth in Vclaim 3 in which 4the header has a longitudinal passage and a series lof orices, each orifice placing one of `the conduits of the unitary plate in communication with said longitudinal passage.

7. In an levaporator of the type in which the ymain body is formed by an extruded plate having ya plurality of conduits formed therein, one side of lthe plate having 'a rs-tiiat surface and the opposite side having projecting ribs which extend over the conduits, each of said conduits having one lof its ends in communication with a distributing header, the improvement which comprises: the extruded plate having a second flat surface which extends across the end of the plate, the distributing hea/der being an extruded shape which has an off-set flange formed with a first flat face which engages the first flat surface o-f the extruded Iplate, the header having a second at face at right angles to the rst flat face, the second flat face engaging the second flat surface of the unitary sheet, said fiat faces being braz'ed 1to said flat surfaces.

The :structure .as set forth in claim f7 in which the vheaderis formed with agroove opening toward fone of said nat surfaces of -the unitary sheet, said groove being adapted to lhold braz- ,5 Iing-material lprior to the brazing operation. l

9. The structure as set forth in claim 'l in which the header :has la groove onl-a side away from .said fiatfaces-and has a plurality of holes extendling `from said groove to one of said flat faces.

10. .The structure as set` forth in claim -7 in Which the header has `a longitudinal passage at .right angles to the conduits of the extruded plate aandhas a series of orifices .formed in said second flat face, each orice vplacing one 'of the conduits of vthe :extruded plate in communication with said longitudinal passage.

11. In .an evaporator Aof the type in which the main body is formed by an extruded plate having a plurality of conduits formed therein, one `side vof .the plate having a flat side Wall and lthe opposite sidelhaving projecting ^ribs which extend over the conduits, the improvement which comprises: Ia 4'header having two lcylindrical passages, one 'of said passages being in communication with the conduits at one 'end of the extruded plate, and the other of said passages vbeing in communication with the conduits at the 4other end of the extruded plate.

l2. The structure as set forth in claim l1 in which the header .-has two laterally extending flanges, each of said anges vbeing in engagement with the ilat side wall of the extruded plate.

13. AIn an evaporator of the type in which the main vbody is formed by an extruded plate havfing a plurality of 'conduits formed therein, one :side -of the plate having a ilat surface and the opposite side having projecting yribs which extend over the conduits, each `of 'said conduits being in communication with a distributing header, the improvement which comprises: each projecting rib being yformed with an aperture, an -inlet tube formed with vapertures which register with Vthe 'apertures in the ribs 4and a vplurality of spuds, -each spud extending into an aperture in a rib f and an aperture in the tube, the p-arts being .brazed together.

14. An evaporator as 4specified in -claim 13 in which each spud has a reduced portion which extends into the aperture in the `rib and an en- 50 larged portion Which extends into the aperture in Ythe tube.

l5. In an evaporator of the type -in which the nmain body is formed by an extruded plate having Va plurality of conduits formed therein, one 55 side of the plate having a flat surface and the opposite side having projecting ribs which extend over the conduits, parts of the plate between the conduits being cutaway to form projecting tubes which .are in communication with a header, the .60 improvement which comprises: the projecting `tubes being lof substantially Dshape in cross section, the header being 4in the form of a tube, the

Wall of the tube being formed with a series of apertures Icorrespond-ing .in shape and location 165 with the D-shaped tubes, the tubes projecting into vand engaging the sides of said apertures and the Wall of the tube engaging the end of the plate between the tubes, the Ycontacting surfaces of the tube and plate being brazed together.

116. In an evaporator of the type in which a plurality of evaporator conduits discharge into `a header and in which ya return line leads 'from the header, the 'improvement which comprises: a :partition locatedin .the-header between the evap- ,75 ora-tor 'conduits and :the return line, said Iparti-- tion dividing the header into a liquid chamber into which the evaporator conduits discharge, and a gas chamber which receives the gas vaporized from the liquid, the position and construction of said partition being such as to prevent passage of liquid refrigerant into the gas chamber and to permit the gas to flow from the liquid chamber into the gas chamber at relatively low velocity thus substantially precluding the passage of liquid refrigerant into the return line, the return line being in communication with the gas chamber.

17. In an evaporator of the type in which a plurality of evaporator conduits discharge into a header and in which a return line leads from the header, the improvement which comprises: a vertical partition located in the header between the evaporator conduits and the return line, said partition dividing the header into a liquid chamber into which the evaporator conduits discharge and a gas chamber which receives the gas vaporized from the liquid, said gas chamber being substantially free from liquid, said partition closing off the entire bore of the header eXcept for an aperture located in the partition, said aperture being at the upper part of the header when the evaporator is in normal position, the return line being in communication with the gas chamber.

18. In an evaporator of the type in which a l 0 plurality of evaporator conduits discharge into a header and in which a return line leads from the header, the improvement which comprises: a horizontal partition located in the header between the evaporator conduits and the return line, said partition dividing the header into a lower liquid chamber into Awhich the evaporator conduits discharge and an upper gas chamber which receives the gas Vaporized from the liquid, the position and length of said horizontal partition being such as to prevent passage of liquid refrigerant into the gas chamber and to permit the gas to flow from the liquid chamber into the gas cha-mber at relatively low velocity thus substantially precluding the passage of liquid refrigerant into the return line, the return line being in communication with the gas chamber.

CHAS. E. HICKMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 25 Number Name Date l1,969,813 Ackerman Aug. 7, 1934 2,212,912 Booth Aug. 27, 1940 2,312,087 Fitzgerald Feb. 23, 1943 2,145,721 Hall Jan. 31, 1939

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