US2055499A - Refrigerating apparatus - Google Patents

Description

Sept. 29, 1936. q:u 2,055,499

REFRIGERATING APPARATUS Filqd March 17,.1933 3 Sheets-Sheet 1 Sept. 29,1936. J. G. KING 2,055,499

REFR IGERAT I NG APPARATUS Filed March 17, 1953 5 Sheets-Sheet 2 Sept. 29, 1936. J, 13, K 2,055,499

REFRIGERATING APPARATUS Filed March 17, 1953 s Sheets-Sheet 5 &

INVENTOR HIS ATTORNEYS.

meme Sept. 29. 1936 V PATENT FFICE REFRIGERATING APPARATUS Jesse G. King, Dayton, Ohio, assignor, by mesne assignments, to General Motors Corporation, a corporation of Delaware Application March 17, 1933, Serial No. 661,209 17 Claims. (01. 62-126) This invention relates to refrigerating systems and more particularly to heat exchange units such as evaporators for such systems.

In the construction of evaporators for refrigerating systems of the type including a plurality of pipes or conduits for distributing refrigerant to be vaporized in the evaporator it has been common practice to out or stamp blank pieces of metal from sheets thereof and to punch or form holes in the blanks so that they can be assembled onto the refrigerant pipes or conduits. The blanks thus produced provide fins for increasing the cooling surface area of such evaporator structures as is well recognized in the art. While such structures have been considered to be satisfactory it has nevertheless been found that the portion of the individual blank fins immediately surrounding the refrigerant conduits are substantially the only part of the individual fins which are effective or 20 efiicient for rapidly absorbing and transmitting heat to the refrigerant in the conduit or conduits of the evaporator. In other words a substantial temperature difference or gradient between portions of the blank fins adjacent the refrigerant 05 conduits and portions thereof more remote from the refrigerant conduits is inherent in such fin structures. A predetermined number of such blank fins are ordinarily assembled on the refrigerant conduits constituting an evaporator to provide an evaporator of a predetermined cooling capacity. Since the portions of such blank fins remote from a conduit or conduits of the evaporator, which portion is inefiective, constitutes a large portion of such fins it is important to devise some means to render these portions of fins efficient or to enable these portions of the fins to be used in a more advantageous manner in the construction of evaporators.

The object of my invention therefore is to provide a heat exchange unit such as an evaporator of a refrigerating system wherein the effective cooling area thereof is materially increased without materially increasing the amount of metal employed in the construction thereof.

A further object is to provide a method of construction and particularly a method of fin construction whereby the heretofore ineffective portions of the metal fins are utilized for the formation of additional fins.

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 discloses an evaporator constructed in accordance with my invention adapted to be connected to a refrigerating system shown diagrammatically;

Fig. 2 is a top plan view of the evaporator shown in Fig. 1;

Fig. 3 is a front view of the evaporator;

Fig. 4 discloses a conventional form of blank fin heretofore employed in the construction of evaporators;

Fig. 5 discloses a blank fin cut or formed in accordance with the present invention to provide two individual fins;

Fig. 6 is a sectional view through my improved evaporator and is taken on the line 6-6 of Fig. 2;

Fig. '7 is a sectional view through my improved evaporator and is taken on the line 1-1 of Fig. 2;

Fig. 8 is an end view of a modified form of evaporator constructed in accordance with my invention;

Fig. 9 is a side view of the evaporator shown in Fig. 8;

Fig. 10 is an end view of a unit employed in the construction of the evaporator shown in Figs. 8 and 9;

Fig. 11 is a side view of the unit shown in Fig. 10;

Fig. 12 is an end view of another unit employed in the construction of the evaporator shown in Figs. 8 and 9; and

Fig. 13 is a side view of the unit shown in Fig. 12.

Referring to the drawings for the purpose of illustrating my invention I show in Fig. 1 a refrigerating system including the customary comonly part of the individual fins which are effective An electric motor i8 operates the compressor [5 through belt and pulley connections l9 and 2i. Liquid refrigerant is conducted to the evaporator l1 through the pipe line 22 and gaseous or evaporated refrigerant is withdrawn from the evaporator ll, by compressor 15, through the vapor pipe line 23. An expansion valve 24 is interposed in the pipe line 22 and is actuated in response to pressures within the evaporator H for admitting liquid refrigerant to the evaporator. The operation of valve 24 is adapted to be modified in accordance with the temperature of the evaporator adjacent the outlet thereof. A thermostat 25 (see Fig. 2) is connected by the pipe 26 to the valve 24 for this purpose. The operation of motor l8 and consequently compressor I5 is controlled by a switch 28 which is actuated by movement of a bellows 21, communicating with the interior of the evaporator II or with the vapor line 23, in response to pressures within the system. As long as the system is functioning normally expansion valve 24 opens and closes automatically in response to pressures in the evaporator and controls the flow of liquid refrigerant thereto. During normal operation of the system the compressor starts and stops in response to pressures in the low pressure portion of the system to maintain the evaporator between predetermined temperature limits.

The evaporator I! in the present disclosure includes two headers 3| and 32 which are in the form of cylinders disposed one above the other. The lower header 3| is provided with an inlet connection 33 for receiving liquid refrigerant from the expansion valve 24 and for directing same to the evaporator. The upper header 32 is provided with a gaseous refrigerant outlet connection 34 adapted to communicate with the vapor pipe line 23 of thesystem. The outlet connection 34 includes an extension or stand-pipe 35 which extends to a point near the top of header 32 (see Fig. 1) so as to prevent entrance of liquid refrigerant into the vapor-return conduit 23. A plurality of straight lengths of pipe 36 are connected to the lower header 3| and extend outwardly or laterally therefrom. A plurality of similar pipes 31 are connected to the upper header 32 and extend outwardly therefrom. The pipes or conduits 36 and 31 extend parallel to one another and are arranged in vertical aligned pairs along the length of the headers and the upper and lower pipes of each of the pairs are connected at their outer ends by U-shaped connections 38. The legs of the U-shaped connections 38 are inserted into and secured to the ends of pipes 36 and 31 in any suitable manner to provide a plurality of refrigerant conveying conduits or ducts connected in parallel with the headers 3| and 32 (see Figs. 2 and 3).

The upper header 32 of the evaporator is provided with a baflie 4| (see Fig. 1) which extends horizontally across the interior thereof and is secured to the walls of the header. Baflie 4| is provided with an opening for receiving the extension or stand-pipe 35 which cooperates with the outlet connection 34. This baiile 4| ispositioned above the point of communication of pipes 31 with header 32 and extends from the front end wall of header 32 to a point spaced from the rear end wall thereof. The space between the end of baiile 4| and the rear wall of header 32 provides a passage 42 for permitting refrigerant to flow from below the battle to the opening in stand-pipe 35 communicating with the outlet connection 34 in header 32 (see Fig. 1). A tubular member 43 is sealed to the front end wall of header 32 (see Fig. 2) and extends into the header above baffle 4|. Member 43 is closed at itsinner end to form a wall for the reception of the thermostat 25 which is adapted to modify the action of expansion valve 24 in response to temperatures of the evaporator ll. Liquid refrigerant is adapted to be maintained by the expansion valve 24 and the thermostat 25 at a substantially constant level below and adjacent to the baille 4| so as to maintain the evaporator in a flooded condition at all times. Thermostat 25 is responsive to the flow of liquid refrigerant above the ballle 4| to actuate expansion valve 24 into closed position to stop the flow of liquid refrigerant to the evaporator and to prevent liquid refrigerant from entering the suction or vapor pipe 23. The

control of a refrigerating system and the maintenance of liquid refrigerant in an evaporator of the type disclosed may be more fully understood by reference to the patent to Harry B. Hull, No. 1,834,949 of December 8, 1931. I have disclosed one form of evaporator construction for illustrating my invention but I wish it to be understood that other various forms may also come within the realm of my invention.

My invention is particularly directed to the method of producing fins and the arrangement thereof on the refrigerant conveying or distributing conduits or ducts of an evaporator with the object in view of reducing to a minimum the material employed in the construction thereof while at the same time obtaining maximum ciliciency of the evaporator. With the foregoing in mind and referring to Fig. 4 of the drawings, I have shown a blank piece of thin metal 46 of the type heretofore employed to provide a fin or fins for 'evaporators. As before stated this blank 46 is ordinarily cut from sheets of metal and holes 41 punched therein to permit insertion of the refrigerant conveying conduits or ducts therein so that the fin or fins will bridge the plurality of ducts constituting the evaporator structure. I have found that substantially the only portions of such blanks 46, when assembled onto the conduits of evaporator structures, which are effective or eflcient for absorbing and conducting the heat, from the medium to be cooled by the evaporator, to refrigerant contained in the evaporator are those portions immediately adjacent or surrounding the refrigerant ducts. I have indicated these effective portions of the blanks or fins 46 as being the portions substantially within the area defined by the dot and dash lines 46 in Fig. 4. In view of the fact that substantially one half of the area or heat absorbing surface of the blank or fin 46 is not effective for the purpose described it is obvious that two fins may be produced from this blank or from a blank of substantially the same size providing a satisfactory method of cutting the blank could be worked out.

Therefore in order to produce or obtain two fins from the blank 46 shown in Fig. 4 or from a blank of substantially the same form and size I cut or stamp the two fins 5| and 52 shown in Fig. 5 from a sheet of thin metal of slightly larger dimension than the dimension of the sheet from which the blank 46 is cut. The dimension of the sheet required to obtain the two fins 5| and 52 over the dimension of the blank 46 is relatively small and is indicated by the dot and dash lines 53 shown in Fig. 5. Each fin 5| and 52 includes a continuous edge portion 54 and outwardly projecting diamond-shaped leg portions 55. Obviously the shape or form of the legs 55 may be varied if desired to meet varying conditions without departing from my invention. Holes 56 in fin 5| and holes 57 in fin 52 are punched in the fins preferably simultaneously with the cutting of the sheet into the individual fins. While I prefer to punch holes 56 and 51 simultaneously as explained, it is to be understood that these holes may be punched prior to severing the blank 46 or they may be punched in the fins 5| and 52 after these fins have been cut from the blank. The holes 56 in fin 5| are equally spaced apart both horizontally and vertically. Holes 51 in fin 52 are spaced apart in accordance with the spacing of holes 56 in fin 5|. The particular design of the die or tool employed for cutting the two individual fins 5| and 52 or the particular cuts through the sheet of metal,

together with the equal or similar spacing of the A predetermined number of the fins 5| and 52 are cut from a sheet of thin metal of good heat conductivity, preferably copper, and are assembled onto the refrigerant conveying or distributing ducts 36 and 31. The assembly of fins 5| and 52 onto ducts or pipes 36 and 3! of the evaporator is of course carried out prior to securing the U-shaped connections 38 to the pipes, or

prior to securing the pipes 36 and 31 to the headers 3| and 32, and these fins may be assembled onto the pipes in any desired manner. The diamond-shaped legs 55 of fins 5| and 52 may all be directed in the same general direction if desired, but are preferably assembled onto the pipes 36 and 3! as disclosed in Figs. 6 and 7 so that the legs 55 of one fin are directed downwardly while the legs 55 of the adjacent fin are directed upwardly. This arrangement is preferable in order to produce a symmetrical evaporator of neat appearance.

After the assembling operation of the fins onto the pipes 36 and 31 of the evaporator has been completed, it being understood of course that the fins are forced onto the ducts or pipes or that the pipes are forced into the holes in the fins to insure good thermal contact therebetween, angle members 6| are placed at the corners of the fins to protect the fins against damage during manipulation of the evaporator in the factory and during shipment thereof. The angle members 6| extend across all the fins included in the construction of the evaporator and may be held in place at the corners of the fins by any suitable means. In the present disclosure I have shown rods 62 comprising a threaded end which protrudes through an opening in the angle members 6| and receives a nut 63. The opposite ends of rods 62 are formed into a hook portion 64 for encircling and gripping the pipes 36 and 31 of the evaporator. The nuts 63 upon-being drawn up tight against member 6| firmly clamps member 6| against the corner of the fins 5| and 52.

An evaporator constructed in accordance with the foregoing description is intended for installation in a refrigerator cabinet wherein a natural circulation of air is created by the cooling eifect produced by the evaporator. However, my invention is not limited to the particular evaporator hereinbefore described because various modifications may be made incorporating the principles of my invention. For example, I have shown in Figs. 8 and 9 of the drawings one form of modified evaporator structure. The evaporator disclosed in Figs. 8 and 9 is designed for installation in a refrigerator cabinet or the like wherein a forced circulation of air is created by means such as fans. In this type of installation the number of refrigerant conduits and the number of fins in contact with-the refrigerant conduits of the evaporator may be greatly increased for providing ample cooling surface to insure cooling of the increased volume of air circulated or forced over the evaporator. Therefore the unitary evaporator structure shown in Figs. 8 and 9 is constructed of two sub-assemblies or units II and 12. The sub-assembly or unit II is shown in Figs. 10 and 11 while the other unit 'I2,is shown in Figs. 12 and 13. The unit H includes a plurality of straight lengths of ducts or pipe 13 upon which are mounted a plurality of fins 14. The

unit I2 includes a plurality of straight lengths of ducts or pipe I5 upon which are mounted a plurality of fins 16. Each of the fins 14 is a complemental part of one of the fins 16 and these fins may be produced from a single sheet of metal as hereinbefore described. It will he noted that the unit ll comprises less refrigerant pipes than the unit 12. This is for the purpose of permitting unit II to be telescoped or moved into unit 12 substantially within the boundary thereof to produce the unitary evaporator structure disclosed in Figs. 8 and 9. It is obvious from the detailed showing of the individual units H and I2 and from the particular fin design that the conduits 13 of unit Il may be moved into the openings or slots between the legs of fins 16 on unit 12. After moving unit 1| into engagement with unit '52 the refrigerant conveying pipes 13 and 15 are connected together at each end of the evaporator by elbows or U-shaped members TI and 18 to provide a compact unitary structure consisting of a continuous conduit or a series of path of fiow for refrigerant through the evaporator. One end of the continuous conduit is provided with a coupling 19 and the other end of the conduit is provided with a coupling 8|. The coupling I9 is adapted to be connected with an exfrigerating system disclosed and the coupling 6| is adapted to be connected with the refrigerant vapor-return conduit 23 of the system. Since this latter described evaporator is primarily intended for installation in conjunction with forced circulation of air thereover or therethrough its compactness provides a maximum of heat ab sorbing surfaces or areas within a minimum amount of space which is a desirable feature of such structures.

It will be apparent from the foregoing that I have provided an improved evaporator, the fin surface of which is constructed of less or substantially one-half the material heretofore used in the construction of such e aporators while at the same time maintaining the same efficiency obtained from evaporators of known structure. My improved evaporator structure also creates an improved and increased air circulation within refrigerator cabinets due to the fact that substantially all of the heat absorbing surfaces of the fins are of the same temperature and are therefore fins more efficient for absorbing and transmitting heat to the refrigerant within the refrigerant expansion conduits of the evaporator thus causing the air to move more rapidly thereover and therethrough. Since all of the heat absorbing surfaces of the fins of my improved evaporator are at substantially the same temperature as the temperature of the refrigerant within the evaporator the temperature of the evaporator can be maintained at a higher degree than prior evaporators wherein a temperature gradient between certain portions of the fins is inherent. By cutting or forming the fins in accordance with my invention so that certain fins of the evaporator are a complemental part of certain other of the fins I provide for the mounting of twice as many fins on the evaporator without materially increasing the weight thereof and at substantially the same cost as providing the required number of fins for evaporatorsheretofore known.

While the forms of embodiments of the invention as herein disclosed. constitutes preferred forms, 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. The method of producing a plurality of fins from a single plate which comprises, forming a plurality of rows of openings in the plate for receiving a plurality of ducts, forming a second plate from portions within the boundary of the first plate remote from the portions thereof adjacent the openings therein and between each of the plurality of rows of openings to provide two fins one of which is a complemental part of the other, and forming openings in the second plate for receiving the plurality of ducts adapted to be received in the openings of the first plate.

2. The method of making a unitary heat exchange structure which comprises, arranging a plurality of refrigerant conveying ducts in parallel elation and assembling a plurality of fins ther on transversely to the longitudinal attis the eof to provide a first unit, arranging a plural y of refrigerant conveying ducts in parallel relation and assembling a plurality of fins thereon transversely to the longitudinal axis thereof to provide a second unit, moving one of the units substantially within the boundary of the other of the units and connecting the ducts of one unit to the ducts of the other unit to provide a unitary structure.

3. Tube heat exchanger, particularly for refrigerating systems, comprising a plurality of fins having openings therein receiving a plurality of 'ubstantially parallelly extending spaced apart r0 s of tubes for increasing the heat transfer surface of the exchanger, characterized by the fact that one fin is formed as a complemental part of another fin from a predetermined sheet area and the complemental fin has a row of tube receiving openings provided in material cut from said sheet area between the two rows of tube receiving openings in the one fin and in which row each tube receiving opening in said sheet area is staggered with respect to the tube receiving openings in each row of the one fin.

4. Tube heat exchanger according to claim 3, characterized by the fact that the boundary of the material of the fins surrounding each of the tube receiving openings is rhomboidal in form and has the tube receiving openings at the center of the rhombus.

5. An evaporator for refrigerating systems including a plurality of parallelly arranged refrigerant conveying ducts, one or more pairs of fins having a plurality of rows of openings fitting over and engaging the plurality of refrigerant ducts, each pair of fins being formed from a sheet area of the extent ordinarily employed to form one fin, and one of the fins of each pair thereof comprising a portion removed from said sheet area between the rows of openings provided therein for the other fin which is normally inactive when said one fin is used as a single fin.

6. An evaporator for refrigerating systems according to claim 5, in which each fin of said pairs thereof consists of a web with extending portions formed of the material of said sheet area between the rows of openings in one fin being of rhomboidal form and having the refrigerant duct receiving openings in each extending portion at the center of the rhombus.

7. An evaporator for refrigerating systems according to claim 5, which consists of two subunits so telescoped that their fins are displaced relatively to one another, and the refrigerant ducts of one unit extend through spaces in the fins of the other unit.

8. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a fin secured in intimate thermal contact to certain of said ducts, a second fin independent of said first named fin secured in intimate thermal contact to certain of said ducts, both of said fins having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, said second named fin being complementary to said first named fin and including portions removed from said first named fin remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

9. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a fin secured in intimate thermal contact to said plurality of ducts, a second fin independent of said first named fin also secured in intimate thermal contact to said plurality of ducts, both of said fins having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, said second named fin being complementary to said first named fin and including portions removed from said first named fin remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

10. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a fin secured in intimate thermal contact to certain of said ducts, a second fin independent of said first named fin secured in intimate thermal contact to certain other of said ducts, both of said fins having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, said second named fin being complementary to said first named fin and including portions removed from said first named fin remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

11. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a group of fins secured in intimate thermal contact to certain of said ducts and extending transversely to the longitudinal axis thereof, a second group of fins secured in intimate thermal contact to certain of said ducts and extending transversely to the langitudinal axis thereof, the fins of each group thereof having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, a certain individual fin of said second named group being complementary to a certain individual fin of said first named group and including portions removed from said certain fin of said first named group remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

12. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a group of fins secured in intimate thermal contact to certain of said ducts and extending transversely to the longitudinal axis thereof, a second group of fins secured in intimate thermal contact to certain other of said ducts and extending transversely to the longitudinal axis thereof, the fins of each group thereof having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, a certain individual fin of said second named group being complementary to a certain individual fin of said first named group and including portions removed from said certain fin of said first named group remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

13. An evaporator for refrigerating apparatus including a plurality of parallelly arranged refrigerant conveying ducts, a group of fins secured in intimate thermal contact to said plurality of ducts and extending transversely to the longitudinal axis thereof, a second group of fins also secured in intimate thermal contact to said plurality of ducts and extending transversely to the longitudinal axis thereof, the fins of each group thereof having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, a certain individual fin of said second named group being complementary to a certain individual fin of said first named group and including portions removed from said certain fin of said first named group remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

14. An evaporator for refrigerating apparatus comprising in combination, a pair of headers, a plurality of refrigerant conveying ducts connected in parallel to said headers, a fin secured in intimate thermal contact to said ducts and extending transversely to the longitudinal axis thereof, a second fin independent of said first named fin also secured in intimate thermal contact to said ducts and extending transversely to the longitudinal axis thereof, both of said fins having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, said second named fin being complementary to said first named fin and including portions removed from said first named fin remote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

15. An evaporator for refrigerating apparatus comprising in combination, a pair of horizontally disposed headers extending parallel to one another, a plurality of refrigerant conveying ducts connected in parallel to said headers and extending laterally therefrom, a fin secured in intimate thermal contact to said ducts and extending transversely to the longitudinal axis thereof, a second fin independent of said first named fin also secured in intimate thermal contact to said ducts and extending transversely to the longitudinal axis thereof, both of said fins having a plurality of transverse and a plurality of perpendicular rows of openings therein for the reception of said refrigerant ducts, said second named fin being complementary to said first named fin and including portions removed from said first named fin re mote from and between each of the plurality of rows of openings therein adapted to be secured to said ducts.

16. A method of making fins each adapted to cooperate with a plurality of the tubes of a tubular heat exchanger, characterized by the fact that from a rectangular sheet area extensions or fiaps are cut out on a common web portion coinciding with one long side of the sheet area, that part of the sheet area coinciding with the other long side forming a web portion for sheet parts located between said extensions for the purpose of obtaining without loss of material and from a sheet area of substantially the same size as previouslyused for the formation of one fin two substantially uniform fins one of which is formed from portions inactive for the heat transferring action of the other fin.

17. A method of making fins each adapted to cooperate with a plurality of the tubes of a tubular heat exchanger, characterized by the fact that from a rectangular sheet area rhomboidal extensions or flaps are cut out on a common web portion coinciding with one long side of the sheet area, that part of the sheet area coinciding with the other long side forming a web portion for sheet parts located between said extensions for the purpose of obtaining without loss of material and from a sheet area of substantially the same size as previously used for the formation of one fin two substantially uniform fins one of which is formed from portions inactive for the heat transferring action of the other fin.

JESSE G. KING.

CERTIFICATE OF CORRECTION.

Patent No. 2,055,499. September 29, 1936.

JESSE G. KING.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1 second column, line 38, strike out the words '.'only part of the individual fins which are effective" and insert instead the syllable, words and period pressor 15, a condenser 16 and an evaporator 17. and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of December A. D. 1956.

Henry Van .arsdale (Seal) Acting Commi ssioner of Patents.

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