Heat exchangers and method of making same
United States Patent 3901312
A heat exchanger embodying an elongated tubular member with integral elongated fins extending transversely thereacross and projecting outwardly therefrom, the fins having internal openings extending therethrough.
US Patent References:
Production of externally finned sheet stock
Hansson et al. - April 1966 - 3247583
Extensive surface heat exchanger
Popovitch - August 1966 - 3269459
GRADATED HEAT EXCHANGE FINS
Kritzer - November 1970 - 3540530
Production of externally finned sheet stock
Hansson et al. - April 1966 - 3247583
Extensive surface heat exchanger
Popovitch - August 1966 - 3269459
GRADATED HEAT EXCHANGE FINS
Kritzer - November 1970 - 3540530
Application Number:
05/438750
Publication Date:
08/26/1975
Filing Date:
02/01/1974
View Patent Images:
Export Citation:
Assignee:
Peerless of America, Incorporated (Chicago, IL)
Primary Class:
Other Classes:
29/890.046
International Classes:
F28F1/26; F28F1/24; F28F1/16
Field of Search:
165/181-183 9/170,171 29/157.3V
Primary Examiner:
Myhre, Charles J.
Assistant Examiner:
Streule, Theophil W.
Attorney, Agent or Firm:
Root & O'Keeffe
Claims:
I claim
1. A heat transfer element comprising
2. spaced from each other longitudinally of said wall, and
3. projecting outwardly from said outer face,
4. elongated base portions
5. outer longitudinal edges, and
6. a plurality of openings therethrough
7. A heat exchanger as defined in claim 1, and in which
8. A heat exchanger as defined in claim 2, and in which
9. A heat exchanger as defined in claim 3, and in which
10. substantially parallel to, and
11. substantially the same length as said base portions of the respective ones of said fins on which they are disposed.
1. A heat transfer element comprising
2. spaced from each other longitudinally of said wall, and
3. projecting outwardly from said outer face,
4. elongated base portions
5. outer longitudinal edges, and
6. a plurality of openings therethrough
7. A heat exchanger as defined in claim 1, and in which
8. A heat exchanger as defined in claim 2, and in which
9. A heat exchanger as defined in claim 3, and in which
10. substantially parallel to, and
11. substantially the same length as said base portions of the respective ones of said fins on which they are disposed.
Description:
BACKGROUND OF THE INVENTION
This invention relates to heat exchangers and, more particularly, to heat exchangers of the finned type.
It is a primary object of the present invention to afford a novel heat exchanger and a novel method of making the same.
Another object is to afford a novel finned heat exchanger wherein the fins are formed by cutting or gouging the same from wall portions of the heat exchanger.
Another object of the present invention is to enable a novel heat exchanger to be afforded in a novel and expeditious manner wherein secondary heat transfer surfaces may be formed by cutting or gouging them out of tubular stock to afford fins having internal openings extending therethrough.
An object ancillary to the foregoing is to enable such heat exchangers to be afforded in a novel and expeditious manner with elongated openings through the fins thereof.
Heat exchangers embodying fins formed from the outer surface material of tubular members have been heretofor known in the art, being disclosed, for example, in Richard W. Kritzer U.S. Pat. No. 3,202,212 and Joseph M. O'Connor U.S. Pat. No. 3,692,105, wherein, in the forementioned Kritzer patent, the fins are in the form of spines formed from outwardly projecting ribs on the tubular member; and in the aforementioned O'Connor patent, the fins are formed by cutting or gouging them from such outwardly projecting ribs and the portion of the tubular member directly underlying the ribs, to thereby afford fins having elongated base portions projecting outwardly from the side wall of the tubular member, with spaced spines projecting outwardly from the outer longitudinal edges of the base portions. Heat exchangers of the type disclosed in the aforementioned Kritzer and O'Connor patents have proven to be very effective. However, it is an object of the present invention to afford improvements over heat exchangers of the type disclosed in the aforementioned Kritzer and O'Connor patents.
Another object of the present invention is to afford a novel heat exchanger of the finned type, wherein the fins are constructed in a novel and expeditious manner.
A further object of the present invention is to increase the amount of secondary heat transfer surface on finned heat exchangers in a novel and expeditious manner.
One of the disadvantages commonly encountered in finned heat exchangers of the type wherein spines are cut or gouged from outwardly projecting ribs on a tubular member is that the spines project outwardly at uneven lengths from the underlying wall of the tubular member, so that the outer ends or edges of the fines are not disposed in uniplanar relation to each other. It is an important object of the present invention to enable a heat exchanger of the type embodying outwardly projecting fins, which are cut or gouged from rectangular-shaped tubular stock, and the like, to be formed in a novel and expeditious manner effective to afford a substantially uniplanar disposition of the outer ends or edges of the fins.
Another object of the present invention is to afford a novel heat exchanger of the finned type, which is practical and efficient in operation, and which may be readily and economically produced commercially.
Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show the preferred embodiments of the present invention and the principles thereof, and what I now consider to be the best modes in which I have contemplated applying these principles. Other embodiments of the present invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.
DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a length of heat exchanger element embodying the principles of the present invention;
FIG. 2 is a longitudinal sectional view taken substantially along the line 2--2 in FIG. 1;
FIG. 3 is a transverse sectional view taken substantially along the line 3--3 in FIG. 2;
FIG. 4 is a transverse sectional view taken substantially along the line 4-4 in FIG. 2; and
FIG. 5 is a transverse sectional view, similar to FIG. 3, but showing a modified form of the present invention.
DESCRIPTION OF THE EMBODIMENTS SHOWN HEREIN
A heat exchanger element or heat transfer element 1, embodying the principles of the present invention, is shown in FIGS. 1-4 of the drawings as one end portion of an elongated tubular member 2, to illustrate the presently preferred embodiment of the present invention, and to illustrate the presently preferred method of making heat exchangers in accordance with the principles of the present invention.
As will be discussed in greater detail hereinafter, in the preferred practice of the present invention, the heat exchanger element 1 is preferably formed from a suitable length of tubular stock, such as the tubular member 2, working from one end portion A of the tubular member 2, FIG. 2, toward the other end B thereof, and severing the heat exchanger 1 from the remainder B-C of the tubular member 2 upon completion of the forming of the desired length of heat exchanger, such as the length A-C.
The heat exchanger element 1 embodys, in general, an elongated, tubular body portion 3 having elongated fins 4 projecting outwardly therefrom, each of the fins 4 embodying an elongated base 5 and an elongated outer edge 6, FIGS. 1 and 2.
The tubular member 2 shown in the drawings is substantially rectangular in transverse cross-section, embodying a top wall 7 and a bottom wall 8 disposed in substantially parallel relation to each other, and two oppositely disposed side walls 9 and 10 extending between respective side edges of the walls 7 and 8 in substantially perpendicular relation thereto. Preferably, the walls 7 and 8 are substantially flat, for a purpose which will be discussed in greater detail hereinafter. The side walls 9 and 10 may be of any suitable shape, but I prefer that the outer faces thereof be convex-outwardly in shape, as shown in FIGS. 1, 3 and 4.
A plutality of openings 11, 12, 13 and 14, separated from each other by partition walls or panels 15, 16 and 17, respectively, extend longitudinally through the tubular member 2. As will be appreciated by those skilled in the art, the tubular member 2 is shown in FIGS. 1-4 as having a plurality of openings 11-14 extending therethrough merely by way of illustration and not by way of limitation, and tubular members having a single opening extending longitudinally therethrough may be afforded, without departing from the purview of the present invention.
In the heat exchanger 1 shown in the drawings, the fins 4 project outwardly from the outer faces of two walls 7a and 8a, FIGS. 2 and 4, corresponding to, and, in fact, formed from walls 7 and 8 of the tubular member 2, as will be discussed in greater detail presently. The fins 4 extend longitudinally across the respective walls 7a and 8a, transversely to, and, preferably, in substantially perpendicular relation to the length of the tubular body portion 3, and each of the fins 4 embodies one of the aforementioned elongated bases 5 which is integral with the respective wall 7a and 8a to which it is attached. Each of the fins 4 projects outwardly from the respective wall 7a or 8a, and, preferably, is disposed in substantially perpendicular relation thereto. The outer edges 6 of each of the fins 4, which are disposed on respective sides of tubular body portion 3, preferably are disposed in uniplanar relation to each other. Each of the walls 7 and 8 of the tubular member 2 embodys an outer face 18 and an inner face 19, FIGS. 1, 2 and 3.
The tubular member 2 from which the heat exchanger 1 is made, may be of any suitable material, such as, for example, aluminum. The tubular member 2 may be made in any suitable manner, such as, for example, by extruding the same, and in addition to the openings or passageways 11-14, embodys a plurality of elongated openings or passageways 20 formed in and extending longitudinally through each of the walls 7 and 8 thereof. The openings 20 are transversely spaced from each other, and preferably are round in transverse cross-section. The openings 20 are disposed in inwardly spaced relation to the faces 18 and 19 of each of the walls 7 and 8, and are disposed in any suitable position laterally of the respective walls 7 and 8, being shown in the drawings hereof as being disposed in longitudinal alignment with the vertical center lines of the partition walls 15-17, FIGS. 1 and 2.
In making the heat exchanger 1, a tubular member such as the tubular member 2, having the openings 20 extending through the full length thereof, may first be formed. Thereafter, the fins 4 may be successively formed on each of the side walls 7 and 8 from one end portion of the tubular member 2, such as the end portion A, toward the other end B thereof, FIG. 2. The fins 4 may each be cut or gouged from the walls 7 and 8 by means of a suitable cutting tool, which first cuts along lengthwise of the respective face 18 to the right, as viewed in FIG. 2 to form the surface 21 which extends transversely across the openings 20 and terminates at its inner end, at a horizontal plane disposed between the openings 20 and the adjacent inner face 19 of the respective wall 7 or 8. The fin 4 which has been cut or gouged from the body portion 2, is then bent outwardly, preferably to a position approximately perpendicular to the plane of the wall 7 or 8 on which it is formed.
This formation of the fins 4 by the passage of a cutting tool transversely across and longitudinally along the openings 20, causes an elongated opening 22 to be formed in each of the finished fins 4 at that location wherein the cutting tool cuts across the corresponding one of the openings 20, FIGS. 1, 2 and 3.
It has been found that when fins are formed in the manner hereinbefore described with respect to the fins 4, the compression of the fin material during the cutting operation causes the width of the fins to be substantially less than the length of cut, commonly being in the nature of one-half of the length of cut, so that, for example, to afford fins 4 with a width of one-half inch, the length of cut along the surface 21 would be substantially 1 inch. The fins 4 may be of any suitable thickness, and the thickness of fins of the type of the fins 4 may commonly be in the range of two-thousandths of an inch to one-eight of an inch when the fins 4 are formed in the above described manner. The openings 22 may be formed therein with a length several times, such as, for example, six to eight times, the diameter or vertical width of the openings 20 from which they are formed. For example, with the openings 20 having a diameter of 0.02 inches and with the length of cut along the surface 21 being 1 inch, to afford a fin 4 having a width of one half inch, the length of the slots 22 may be approximately 0.160 inch.
After thus forming the fins 4 along the desired length of the tubular member 2, such as the length A-C, the tubular member 2 may be served transversely to its length at any points between points A and C to thereby afford a finished heat exchanger element having fins 4 extending substantially the full length thereof. As will be appreciated by those skilled in the art, if desired, the formation of the fins 4 may be commenced inwardly of the end portion A of the tubular member 2, and the tubular member 2 may be severed outwardly to the left, as viewed in FIG. 2, of the last formed fin 4 to thereby afford end portions which project outwardly from the outermost fins 4, to afford connecting members at each end of the finished heat exchanger. In such last mentioned construction, not shown, the wall portion 7 and 8 of the tubular member 2 disposed outwardly of the aforementioned outermost fins 4, preferably are reduced in thickness to that of the wall portions 7a and 8a by suitable means, such as, for example, grinding, to thereby afford a smooth-walled end portion for the completed heat exchanger, with the thickness of the top and bottom walls of the end portions being the same as that of the walls 7a and 8a of the heat exchanger.
In FIG. 5 of the drawings, a heat exchanger 1a is shown to illustrate a modified form of the present invention, parts which are the same as parts in the heat exchanger 1 shown in FIGS. 1-4 being indicated by the same reference numerals, and parts which are similar to parts of the heat exchanger being indicated by the same reference numerals, with the suffix "a" added thereto.
In the heat exchanger 1a, the openings 20a through the walls 7 and 8 of the tubular member 2a are vertically elongated, FIG. 5. As a result, when the fins 4a are formed in the same manner, and with the same length of cut as heretofor discussed with respect to the formation of the fins 4, the openings 22a formed in the fins 4a are of greater length than the openings 22 in the fins 4.
It will be seen that by changing the diameter of a round opening, such as, the opening 20 in the tubular member 2, or by changing the width of such openings in a vertical direction, such as, for example, by forming the elongated openings 20a in the tubular member 2a, the length of the opening formed in the finished fin may be varied without varying the length of the path of travel of the cutting tool forming the fin.
As will be appreciated by those skilled in the art, the round openings 20 and the substantially oblong openings 20a are shown herein merely by way of illustration, and not by way of limitation, and openings having other suitable transverse cross-sectional shapes, such as, for example, triangular or square, may be used without departing from the purview of the present invention.
With the fins 4 and 4a, shown herein, having the openings 22 and 22a, respectively, therethrough, the heat transfer surface of the secondary heat transfer surfaces afforded by the fins 4 and 4a is substantially increased.
In addition, the openings 22 and 22a afford passageways through which air or other suitable working fluid may pass transversely through the fins 4 and 4a, respectively.
Also, it will be seen that the openings 22 and 22a disrupt the otherwise smooth surfaces of the fins 4 and 4a, respectively, in which they are disposed, so that they tend to create turbulence in working fluid passing across the fins 4 or 4a, even when such passage of working fluid is longitudinally along the fins 4 and 4a.
It will be remembered that, preferably, the outer faces 18 of the top walls 7 and 8 of the tubular members 2 and 2a are substantially flat. It has been found that when this is true, and fins, such as the fins 4 and 4a are formed in the manner heretofor described, uniplanar relation of the outer edges 6 of the fins 4 on each side of the heat exchanger elements 1 and 1a is substantially insured. As will be appreciated by those skilled in the art, this is of importance, particularly, when the heat exchanger elements are to be disposed in stacked or closely spaced relation to each other.
From the foregoing, it will be seen that the present invention affords a novel heat exchanger of the finned type.
In addition, it will be seen that the present invention affords a novel method of forming a finned heat exchanger, having openings extending through the fins.
Also, it will be seen that the present invention affords a novel heat exchanger which is practical and efficient in operation, and which may be readily and economically produced commercially.
Thus, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.
This invention relates to heat exchangers and, more particularly, to heat exchangers of the finned type.
It is a primary object of the present invention to afford a novel heat exchanger and a novel method of making the same.
Another object is to afford a novel finned heat exchanger wherein the fins are formed by cutting or gouging the same from wall portions of the heat exchanger.
Another object of the present invention is to enable a novel heat exchanger to be afforded in a novel and expeditious manner wherein secondary heat transfer surfaces may be formed by cutting or gouging them out of tubular stock to afford fins having internal openings extending therethrough.
An object ancillary to the foregoing is to enable such heat exchangers to be afforded in a novel and expeditious manner with elongated openings through the fins thereof.
Heat exchangers embodying fins formed from the outer surface material of tubular members have been heretofor known in the art, being disclosed, for example, in Richard W. Kritzer U.S. Pat. No. 3,202,212 and Joseph M. O'Connor U.S. Pat. No. 3,692,105, wherein, in the forementioned Kritzer patent, the fins are in the form of spines formed from outwardly projecting ribs on the tubular member; and in the aforementioned O'Connor patent, the fins are formed by cutting or gouging them from such outwardly projecting ribs and the portion of the tubular member directly underlying the ribs, to thereby afford fins having elongated base portions projecting outwardly from the side wall of the tubular member, with spaced spines projecting outwardly from the outer longitudinal edges of the base portions. Heat exchangers of the type disclosed in the aforementioned Kritzer and O'Connor patents have proven to be very effective. However, it is an object of the present invention to afford improvements over heat exchangers of the type disclosed in the aforementioned Kritzer and O'Connor patents.
Another object of the present invention is to afford a novel heat exchanger of the finned type, wherein the fins are constructed in a novel and expeditious manner.
A further object of the present invention is to increase the amount of secondary heat transfer surface on finned heat exchangers in a novel and expeditious manner.
One of the disadvantages commonly encountered in finned heat exchangers of the type wherein spines are cut or gouged from outwardly projecting ribs on a tubular member is that the spines project outwardly at uneven lengths from the underlying wall of the tubular member, so that the outer ends or edges of the fines are not disposed in uniplanar relation to each other. It is an important object of the present invention to enable a heat exchanger of the type embodying outwardly projecting fins, which are cut or gouged from rectangular-shaped tubular stock, and the like, to be formed in a novel and expeditious manner effective to afford a substantially uniplanar disposition of the outer ends or edges of the fins.
Another object of the present invention is to afford a novel heat exchanger of the finned type, which is practical and efficient in operation, and which may be readily and economically produced commercially.
Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show the preferred embodiments of the present invention and the principles thereof, and what I now consider to be the best modes in which I have contemplated applying these principles. Other embodiments of the present invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.
DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a length of heat exchanger element embodying the principles of the present invention;
FIG. 2 is a longitudinal sectional view taken substantially along the line 2--2 in FIG. 1;
FIG. 3 is a transverse sectional view taken substantially along the line 3--3 in FIG. 2;
FIG. 4 is a transverse sectional view taken substantially along the line 4-4 in FIG. 2; and
FIG. 5 is a transverse sectional view, similar to FIG. 3, but showing a modified form of the present invention.
DESCRIPTION OF THE EMBODIMENTS SHOWN HEREIN
A heat exchanger element or heat transfer element 1, embodying the principles of the present invention, is shown in FIGS. 1-4 of the drawings as one end portion of an elongated tubular member 2, to illustrate the presently preferred embodiment of the present invention, and to illustrate the presently preferred method of making heat exchangers in accordance with the principles of the present invention.
As will be discussed in greater detail hereinafter, in the preferred practice of the present invention, the heat exchanger element 1 is preferably formed from a suitable length of tubular stock, such as the tubular member 2, working from one end portion A of the tubular member 2, FIG. 2, toward the other end B thereof, and severing the heat exchanger 1 from the remainder B-C of the tubular member 2 upon completion of the forming of the desired length of heat exchanger, such as the length A-C.
The heat exchanger element 1 embodys, in general, an elongated, tubular body portion 3 having elongated fins 4 projecting outwardly therefrom, each of the fins 4 embodying an elongated base 5 and an elongated outer edge 6, FIGS. 1 and 2.
The tubular member 2 shown in the drawings is substantially rectangular in transverse cross-section, embodying a top wall 7 and a bottom wall 8 disposed in substantially parallel relation to each other, and two oppositely disposed side walls 9 and 10 extending between respective side edges of the walls 7 and 8 in substantially perpendicular relation thereto. Preferably, the walls 7 and 8 are substantially flat, for a purpose which will be discussed in greater detail hereinafter. The side walls 9 and 10 may be of any suitable shape, but I prefer that the outer faces thereof be convex-outwardly in shape, as shown in FIGS. 1, 3 and 4.
A plutality of openings 11, 12, 13 and 14, separated from each other by partition walls or panels 15, 16 and 17, respectively, extend longitudinally through the tubular member 2. As will be appreciated by those skilled in the art, the tubular member 2 is shown in FIGS. 1-4 as having a plurality of openings 11-14 extending therethrough merely by way of illustration and not by way of limitation, and tubular members having a single opening extending longitudinally therethrough may be afforded, without departing from the purview of the present invention.
In the heat exchanger 1 shown in the drawings, the fins 4 project outwardly from the outer faces of two walls 7a and 8a, FIGS. 2 and 4, corresponding to, and, in fact, formed from walls 7 and 8 of the tubular member 2, as will be discussed in greater detail presently. The fins 4 extend longitudinally across the respective walls 7a and 8a, transversely to, and, preferably, in substantially perpendicular relation to the length of the tubular body portion 3, and each of the fins 4 embodies one of the aforementioned elongated bases 5 which is integral with the respective wall 7a and 8a to which it is attached. Each of the fins 4 projects outwardly from the respective wall 7a or 8a, and, preferably, is disposed in substantially perpendicular relation thereto. The outer edges 6 of each of the fins 4, which are disposed on respective sides of tubular body portion 3, preferably are disposed in uniplanar relation to each other. Each of the walls 7 and 8 of the tubular member 2 embodys an outer face 18 and an inner face 19, FIGS. 1, 2 and 3.
The tubular member 2 from which the heat exchanger 1 is made, may be of any suitable material, such as, for example, aluminum. The tubular member 2 may be made in any suitable manner, such as, for example, by extruding the same, and in addition to the openings or passageways 11-14, embodys a plurality of elongated openings or passageways 20 formed in and extending longitudinally through each of the walls 7 and 8 thereof. The openings 20 are transversely spaced from each other, and preferably are round in transverse cross-section. The openings 20 are disposed in inwardly spaced relation to the faces 18 and 19 of each of the walls 7 and 8, and are disposed in any suitable position laterally of the respective walls 7 and 8, being shown in the drawings hereof as being disposed in longitudinal alignment with the vertical center lines of the partition walls 15-17, FIGS. 1 and 2.
In making the heat exchanger 1, a tubular member such as the tubular member 2, having the openings 20 extending through the full length thereof, may first be formed. Thereafter, the fins 4 may be successively formed on each of the side walls 7 and 8 from one end portion of the tubular member 2, such as the end portion A, toward the other end B thereof, FIG. 2. The fins 4 may each be cut or gouged from the walls 7 and 8 by means of a suitable cutting tool, which first cuts along lengthwise of the respective face 18 to the right, as viewed in FIG. 2 to form the surface 21 which extends transversely across the openings 20 and terminates at its inner end, at a horizontal plane disposed between the openings 20 and the adjacent inner face 19 of the respective wall 7 or 8. The fin 4 which has been cut or gouged from the body portion 2, is then bent outwardly, preferably to a position approximately perpendicular to the plane of the wall 7 or 8 on which it is formed.
This formation of the fins 4 by the passage of a cutting tool transversely across and longitudinally along the openings 20, causes an elongated opening 22 to be formed in each of the finished fins 4 at that location wherein the cutting tool cuts across the corresponding one of the openings 20, FIGS. 1, 2 and 3.
It has been found that when fins are formed in the manner hereinbefore described with respect to the fins 4, the compression of the fin material during the cutting operation causes the width of the fins to be substantially less than the length of cut, commonly being in the nature of one-half of the length of cut, so that, for example, to afford fins 4 with a width of one-half inch, the length of cut along the surface 21 would be substantially 1 inch. The fins 4 may be of any suitable thickness, and the thickness of fins of the type of the fins 4 may commonly be in the range of two-thousandths of an inch to one-eight of an inch when the fins 4 are formed in the above described manner. The openings 22 may be formed therein with a length several times, such as, for example, six to eight times, the diameter or vertical width of the openings 20 from which they are formed. For example, with the openings 20 having a diameter of 0.02 inches and with the length of cut along the surface 21 being 1 inch, to afford a fin 4 having a width of one half inch, the length of the slots 22 may be approximately 0.160 inch.
After thus forming the fins 4 along the desired length of the tubular member 2, such as the length A-C, the tubular member 2 may be served transversely to its length at any points between points A and C to thereby afford a finished heat exchanger element having fins 4 extending substantially the full length thereof. As will be appreciated by those skilled in the art, if desired, the formation of the fins 4 may be commenced inwardly of the end portion A of the tubular member 2, and the tubular member 2 may be severed outwardly to the left, as viewed in FIG. 2, of the last formed fin 4 to thereby afford end portions which project outwardly from the outermost fins 4, to afford connecting members at each end of the finished heat exchanger. In such last mentioned construction, not shown, the wall portion 7 and 8 of the tubular member 2 disposed outwardly of the aforementioned outermost fins 4, preferably are reduced in thickness to that of the wall portions 7a and 8a by suitable means, such as, for example, grinding, to thereby afford a smooth-walled end portion for the completed heat exchanger, with the thickness of the top and bottom walls of the end portions being the same as that of the walls 7a and 8a of the heat exchanger.
In FIG. 5 of the drawings, a heat exchanger 1a is shown to illustrate a modified form of the present invention, parts which are the same as parts in the heat exchanger 1 shown in FIGS. 1-4 being indicated by the same reference numerals, and parts which are similar to parts of the heat exchanger being indicated by the same reference numerals, with the suffix "a" added thereto.
In the heat exchanger 1a, the openings 20a through the walls 7 and 8 of the tubular member 2a are vertically elongated, FIG. 5. As a result, when the fins 4a are formed in the same manner, and with the same length of cut as heretofor discussed with respect to the formation of the fins 4, the openings 22a formed in the fins 4a are of greater length than the openings 22 in the fins 4.
It will be seen that by changing the diameter of a round opening, such as, the opening 20 in the tubular member 2, or by changing the width of such openings in a vertical direction, such as, for example, by forming the elongated openings 20a in the tubular member 2a, the length of the opening formed in the finished fin may be varied without varying the length of the path of travel of the cutting tool forming the fin.
As will be appreciated by those skilled in the art, the round openings 20 and the substantially oblong openings 20a are shown herein merely by way of illustration, and not by way of limitation, and openings having other suitable transverse cross-sectional shapes, such as, for example, triangular or square, may be used without departing from the purview of the present invention.
With the fins 4 and 4a, shown herein, having the openings 22 and 22a, respectively, therethrough, the heat transfer surface of the secondary heat transfer surfaces afforded by the fins 4 and 4a is substantially increased.
In addition, the openings 22 and 22a afford passageways through which air or other suitable working fluid may pass transversely through the fins 4 and 4a, respectively.
Also, it will be seen that the openings 22 and 22a disrupt the otherwise smooth surfaces of the fins 4 and 4a, respectively, in which they are disposed, so that they tend to create turbulence in working fluid passing across the fins 4 or 4a, even when such passage of working fluid is longitudinally along the fins 4 and 4a.
It will be remembered that, preferably, the outer faces 18 of the top walls 7 and 8 of the tubular members 2 and 2a are substantially flat. It has been found that when this is true, and fins, such as the fins 4 and 4a are formed in the manner heretofor described, uniplanar relation of the outer edges 6 of the fins 4 on each side of the heat exchanger elements 1 and 1a is substantially insured. As will be appreciated by those skilled in the art, this is of importance, particularly, when the heat exchanger elements are to be disposed in stacked or closely spaced relation to each other.
From the foregoing, it will be seen that the present invention affords a novel heat exchanger of the finned type.
In addition, it will be seen that the present invention affords a novel method of forming a finned heat exchanger, having openings extending through the fins.
Also, it will be seen that the present invention affords a novel heat exchanger which is practical and efficient in operation, and which may be readily and economically produced commercially.
Thus, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.