Heat exchanger and method of making same

Abstract: A heat exchanger (20) comprises a first tank (21) and a second tank (22) spaced vertically from the first tank (21). The first tank (21) includes a first partition (51,52) disposed therein to divide the first tank into a first number of chambers (28,29,30), wherein the first number of chambers (28,30) is at least two and has respectively an inlet (45) to allow the heat transfer medium to enter the heat exchanger (20) and an outlet (46) to allow the heat transfer medium to exit the heat exchanger (20). The second tank (22) includes a second partition (33) disposed therein to divide the second tank (22) into a second number of chambers (32,33), wherein the second number of chambers (32,33) is preferably one less than the first number of chambers (28,29,30). The first tank (21) and the second tank (22) respectively include a concave surface (60,61,62,63,64,65) horizontally formed on walls (21a,21b,22a,22b) of the tanks, wherein one end of each of the first and second partitions respectively insert into each of the concave surfaces (60-65) for preventing overturn of the partitions during assembly of the tanks (21,22).

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to a heat exchanger and method for making a heat exchanger for use in an air conditioning system for vehicles, and more particularly, to a heat exchanger that allows for efficient and easy assembly. DESCRIPTION OF THE BACKGROUND ART Figs. 1 and 2 show a conventional heat exchanger used in an air conditioning system, for example, an evaporator or a condenser. In Figs. 1 and 2 , a heat exchanger comprises an upper tank 105, a lower tank 110 and heat exchanger core 115 disposed between the upper tank and the lower tank. The heat exchanger core 115 comprises a plurality of beat transfer tubes disposed parallel to one another. The upper tank 105 has an upper wall and a lower wall, which are connected to each other. The upper tank 105 is divided into three chambers by first partition plate 151 and second partition plate 152. First partition plate 151 and second partition plate 152 include respectively notched portions formed in the centers thereof. First partition plate 151 includes a plurality of holes therethrough. Lower tank 110 is divided into two chambers, such as first lower chamber and a second lower chamber, by partition plate 153. Further, the lower tank includes preventing overturn plate 154 therein. Preventing overturn plate 154 includes a notched portion formed in the center thereof and a plurality of holes therein. The number of holes formed in preventing overturn plate 154 as well as their respective diameter is determined so that a heat exchanger medium may pass freely through the holes. The lower wall of the upper tank 105 and the upper wall of the lower tank 110 are provided with a plurality of connection holes, respectively, for interconnecting a plurality of heat transfer tubes therebetween. An inlet pipe 210 and outlet pipe 220 are connected to the upper tank 105. In assembling the upper tank 105 and the lower tank 110, first partition plate 151 is placed on the lower wall of the upper tank 105 so as to be located in the center of the lower wall of the upper tank 105 and second partition plate 152 is connected with first partition plate 151 at right angles to each other, so that the notched portion of second partition plate 152 fixedly inserts into the center notched portion of first partition plate 151 in an attempt to prevent movement and overturning during brazing. Further, in assembling the lower tank 110, partition plate 153 is placed on the lower wall of the lower tank 110 so as to be located in the center of the lower wall of the lower tank 110. In addition, preventing overturn plate 154 is connected with partition plate 153 at a right angle, so that the notched portion of partition plate 153 fixedly inserts into the center notched portion of the preventing overturn plate 154 to prevent movement and overturning during brazing. Finally, the heat exchanger may be placed in a brazing furnace, so that all of its parts may be brazed together. In the arrangement described above, the partition plates 151 and 153 tend to fall down until they are connected with their corresponding partition plate 152 or the preventing overturn plate 154 respectively. Further, the partition plates 151, 152 and 153 and the preventing overturn plate 154 tend to incline and move from the desired location unless these parts are formed to extremely precise sizes. In addition to the above problems, in prior art heat exchangers where partition plates and preventing overturn plates are not formed within very accurate size constraints, the partition plates and the preventing overturn plate often fail to connect with the upper tank 105 and the lower tank 110 during brazing because there exists a gap between the partition plates or preventing overturn plate and the walls of the upper tank 105 and the lower tank 110. As a result of these problems, the brazing step of the assembly process is both complicated and time consuming. These factors cause a reduction in the overall operational productivity of the assembly process. From EP-A-0 450 619 a heat exchanger is known having the features of the preamble of claim 1. The concave portions for guiding the partitions are parallel to each other. From JP-A-3-260 554 a method of manufacturing a heat exchanger is known wherein temporarily a partition plate is fastened to the interior of a header pipe material having a U-shaped cross-section and being provided with a fitting groove. From EP-A-0 374 896 a method of manufacturing a heat exchanger is known wherein partition walls having extensions are fixed to the tanks by fitting the extensions into slots. It is an object of the present invention to provide a heat exchanger and a method for manufacturing the same wherein the assembly is accomplished by a simple and efficient process and wherein a heat exchanger is obtained having good heat exchange capabilities. This object is solved by a heat exchanger comprising the features of claim 1 or claim 9. Furthermore, this object is solved by a method of manufacturing a heat exchanger having the features of claim 6 or claim 8. Preferred developments of the invention are given in the respective subclaims. Fig. 1 is a perspective view of a prior art heat exchanger. Fig. 2 is an exploded view of the heat exchanger illustrated in Fig. 1. Fig. 3 is a plan view of the bottom wall of the top tank in the heat exchanger ellustrated in Fig. 1. Fig. 4 is a perspective view of a heat exchanger in accordance with a first embodiment of the present invention. Fig. 5 is an enlarged sectional view of the heat exchanger illustrated in Fig. 4. Fig. 6 is a schematic perspective view of a heat exchanger, showing an example of a heat exchanger medium flow path. Fig. 7 is an exploded view of the heat exchange unit illustrated in Fig. 4. Fig. 8 is a perspective view of a heat exchanger in accordance with a second embodiment of the present invention. Fig. 9 is an enlarged sectional view of the heat exchanger illustrated in Fig. 8. Fig. 10 is an exploded view of the heat exchange unit illustrated in Fig. 8. Fig. 11 is a perspective view of a heat exchanger in accordance with a third embodiment of the present invention. Fig. 12 is an enlarged sectional view of a heat exchanger illustrated in Fig. 11. DETAILED DESCRIPTION OF THE DRAWINGS A heat exchanger in accordance with a first embodiment of the present invention is illustrated in Figs. 4 and 5. In Figs. 4 and 5 , heat exchanger 20 comprises upper tank 21, lower tank 22 vertically spaced from upper tank 21 and heat exchanger core 23 disposed between upper tank 21 and lower tank 22. Heat exchanger core 23 comprise a plurality of heat transfer tubes 24 spaced from one another and disposed in paralleled to one another. Upper tank 21 includes upper wall 21a and bottom wall 21b, which are connected so as to form an enclosed tank. Upper wall 21a of upper tank 21 includes first concave surface 60 and second concave surface 61 formed inside of upper tank 21 and extending from one horizontal end to other horizontal end. First concave surface 60 and second concave surface 61 are formed to be U-shaped in cross section and are vertically projected toward the outside of upper tank 21. Further, first concave surface 60 and second concave surface 61 are formed to intersect each other and to be substantially perpendicular to each other so as to divide upper wall 21a into four areas. Bottom wall 21b of upper tank 21 includes third concave surface 62 and fourth concave surface 63 formed inside of upper tank 21. Third concave surface 62 and fourth concave surface 63 are formed to be U-shaped in cross section and are vertically projected toward the outside of upper tank 21. Further, third concave surface 62 and fourth concave surface 63 are formed to intersect each other and to be substantially perpendicular to each other so as to divide bottom wall 21b into four areas. Upper wall 22a of lower tank 22 includes concave surface 64 formed inside of lower tank 22. Bottom wall 22b of lower tank 22 includes concave surface 65 formed inside of lower tank 22. Concave surfaces 64 and 65 are formed to be U-shaped in cross section and are vertically projected toward the outside of lower tank 22. Further, concave surfaces 64 and 65 respectively divide upper wall 21a and bottom wall 22b into two areas. Further, upper tank 21 includes end plates 21c and 21d respectively covering both ends of the cylindrical opening which are united with upper wall 21a and bottom wall 21b. Bottom wall 21b of upper tank 21 and upper wall 22a of lower tank 22 are provided with a plurality of connection holes 40 and 41, respectively, for interconnecting a plurality of heat transfer tubes 24 therebetween Upper tank 21 is divided into three chambers, such as first upper chamber 28, second upper chamber 29 and third upper chamber 30 by first partition plate 51 and second partition plate 52. Lower tank 22 is divided into two chambers such as first lower chamber 32 and second lower chamber 33, by partition plate 53 which is inserted into concave surfaces 64 and 65. Inlet pipe 45 and outlet pipe 46 are connected to upper tank 21. Referring to Fig. 6 as well as Figs. 4 and 5 a heat exchanger medium may be introduced via inlet pipe 45 into first upper chamber 28 and may flow down through heat transfer tubes 24 until it reaches first lower chamber 32 of lower tank 22. The medium then may flow back into second upper chamber 29 through heat transfer tubes 24. Further, the heat exchanger medium may then flow from second upper chamber 29 of upper tank 21 through heat transfer tubes 24 into second lower chamber 33 of lower tank 22 and then back to third upper chamber 30 through heat transfer tubes 24. When the heat exchanger medium flows through heat transfer tubes 24, heat is exchanged between the exchanger medium and the air flow 17 passing across heat transfer tubes 24. In a method of assembling upper tank 21 and lower tank 22, referring to Fig. 7 , first partition plate 51 includes notched portion 51a formed in the center thereof and a plurality of holes 51b therein. The plurality of holes 51b are formed with a predetermined number, pitch, and diameter, so that a heat exchanger medium may pass freely through holes 51b of first partition plate 51. Upper wall 21a and bottom wall 21b are formed to be U-shaped in cross section. Concave surfaces 60, 61, 62 and 63 may be formed by a press work. One long end of first partition 51 is inserted into third concave surface 62 of bottom wall 21b of upper tank 21 so as to be positioned in the center of upper tank 21. Second partition plate 52 is connected with first partition plate 51 at a right angle so the notched portion 52a of second partition plate 52 fixedly inserts into center notched portion 51a of first partition plate 51. Thereafter, upper wall 21a is placed on bottom wall 21b so that the other ends of partition plate 51 and 52 are respectively inserted into first concave surface 60 and second concave surface 61. Further, first end plate 21c and second end plate 21d are forcibly inserted into the openings which are formed by upper wall 21a and bottom wall 21b. In assembling lower tank 22, one long end of partition plate 53 is inserted into concave surface 65 of bottom wall 22b of lower tank 22 so as to be positioned in the center of lower tank 22. Thereafter, upper wall 22a is placed on bottom wall 22b so that other end of partition plate 53 is inserted into concave surface 64. Further, first end plate 22c and second end plate 22d are forcibly inserted into the openings which are formed by upper wall 22a and bottom wall 22b. Additionally, both ends of heat transfer tubes 24 are connected with upper tank 21 and lower tank 22 through connection holes 40 of bottom wall 21b and connection holes 41 of upper wall 22a Finally, assembled heat exchanger 10 may be placed in a brazing furnace, so that all of its parts may be simultaneously brazed together. In the arrangement described above, first partition plate 51, second partition plate 52 of upper tank 21, and partition plate 53 of lower tank 53 do not fall down during the assembly process of the tanks. Further, these partition plates do not incline or move from a predetermined place even if the size of the parts, such as partition plates 51, 52, and 53, wall of upper tank 21 and lower tank 22 are not perfectly accurate. Thereby, partition plates 51, 52, and 53 are fixedly and securely connected with upper tank 21 and lower tank 22 by brazing because there is no gap between these partition plates and walls of upper tank 21 and lower tank 22. Further, the concave surfaces have a function which prevents the tanks from being deformed by pressure during operation or brazing. As a result, the heat exchanger of the present invention can be manufactured using a simple process and at a low cost in comparison with the prior art. Figs. 8 and 9 illustrate a second embodiment of the present invention. In this embodiment, upper wall 121a of upper tank 121 includes a first concave surface 70 and a second concave surface 71 formed inside of upper tank 121. The concave surfaces in this embodiment are formed in a box shape. First concave surface 70 and second concave surface 71 project toward the outside of upper tank 121 and are formed to be substantially perpendicular to each other so as to divide upper wall 121a into four areas. Further, first concave surface 70 and second concave surface 71 include openings 70a and 71a respectively, formed outside of upper tank 121 by cutting out the top ends of concaves 70 and 71. Fig. 10 illustrates a method for forming a heat exchanger according to the second embodiment of this invention. Upper wall 121a is placed on bottom wall 121b so that they overlap. Then partition plate 51 is inserted into the inside of upper tank 121 through opening 70a. One long end of partition plate 51 may then be further inserted into concave 72. Second partition plate 52 may be inserted into upper tank 121 through opening 71a and connected with first partition plate 51 at right angles to each other, so that notched portion 52a of second partition plate 52 fixedly inserts into center notched portion 51a of first partition plate 51. One long end of partition plate 52 may be further inserted into concave 73 to prevent the movement thereof during brazing. Finally, partition plate 53 may be inserted into lower tank 122 through opening 74a. Partition plate is then further inserted into concave 75. In such a structure, substantially the same advantages as those in the first embodiment can be obtained. Figs. 11 and 12 illustrate a third embodiment of the present invention. In this embodiment upper wall 21a of upper tank 21 does not include a concave surface inside of upper tank 21. However, bottom wall 21b of upper tank 21 includes a first concave surface 62 and second concave surface 63 vertically projecting toward the outside of upper tank 21 and formed to intersect and be substantially perpendicular to each other so as to divide bottom wall 21b into four areas. Further, upper wall 22a of lower tank 22 does not include a concave surface. Bottom wall 22b of lower tank 22 includes concave surface 65 formed inside of lower tank 22. Concave surface 65 is formed to be U-shaped in cross section and vertically projects toward the outside of lower tank 22. Further, concave surface 65 divides bottom wall 22b of lower tank 22 into two areas. Thereby, in this embodiment, the forming process of a concave can be simplified because upper wall 21a of upper tank 21 and upper wall 22a of lower tank 22 does not include a concave surface.

Claims: A heat exchanger comprising: a first tank (21) including a plurality of connection holes (40), a first partition (51) and a second partition (52) disposed therein to divide said first tank (21) into a first number of chambers, said first tank (21) respectively including an inlet (45) to allow a heat transfer medium to enter said heat exchanger and an outlet (46) to allow a teat transfer medium to exit said heat exchanger; a second tank (22) spaced from said first tank (21) and including a plurality of connection holes (41), and a third partition (53) disposed therein to divide said second tank (22) into a second number of chambers; a plurality of heat transfer tubes (24) fixedly disposed between said first tank (21) and said second tank (22) in fluid communication; said first tank (21) including concave portions (60, 61, 62, 63) horizontally formed on an upper wall (21a) and a bottom wall (21b) of said first tank (21), wherein ends of said first partition (51) and said second partition (52) respectively insert into said concave portions (60, 61, 62, 63; 70, 71, 72, 73) for preventing overturn of said first partition (51) and said second partition (52) during assembly of said first tank (21), said second tank (22) including concave portions (64, 65; 74, 75) horizontally formed on an upper wall (22a) and a bottom wall (22b) thereof, wherein ends of said third partition (53) insert into said concave portions (64, 65; 74, 75) for preventing overturn of said third partition (53) during assembly of said second tank (22); characterized in that said concave portions (60, 61, 62, 63; 70, 71, 72, 73) of said first tank (21) are substantially a cross in shape and said concave portions (64, 65; 74, 75) of said second tank (22) are substantially linear in shape. The heat exchanger of claim 1, wherein said second number of chambers is one less than said first number of chambers. The heat exchanger of claim 1 or 2, wherein said plurality of connection holes (40, 41) are aligned in rows. The heat exchanger of one of claims 1 to 3, wherein said concave portions of said first tank (21) and said second tank (22) are formed to be substantially U-shaped in cross section. The heat exchanger of claim 1, wherein said concave portions of said first tank and said second tank respectively include upper portions formed to be opened to an outside thereof. A method of manufacturing a heat exchanger, as specified in claim 1, comprising the steps of: bending a plurality of planar raw plates to have U-shaped cross sections defining a flat portion and flange portions extending from both ends of said flat portion as an upper wall (21a, 22a) and a bottom wall (21b, 22b) of said first tank (21) and said second tank (22); opening a plurality of connection holes (40, 41) on said flat portion of said bottom wall (21b) of said first tank (21) and said upper wall (22a) of said second tank (22); forming concave portions (60, 61, 62, 63) on said flat portion of said upper wall (21a) and said bottom wall (21b) of said first tank substantially in cross shape; inserting an end of said first partition (51) into one concave portion (62) of said bottom wall (21b) of said first tank (21) and inserting one end of said second partition (52) into one concave portion (63) of said bottom wall (21b) of said first tank (21) so that said second partition (52) is substantially perpendicular to said first partition (51); placing said upper wall (21a) of said first tank (21) on said bottom wall (21b) of said first tank (21) so that said upper wall (21a) is overlapped with said bottom wall (21b) of said first tank (21), and the other ends of said first partition (51) and said second partition (52) insert into said concave portions (60, 61) of said upper wall (21a) and said bottom wall (21b) of said first tank (21); inserting one end of the third partition (53) into the linear concave portion (65) of said bottom wall (22b) of said second tank (22); placing said upper wall (22a) of said second tank (22) on said bottom wall (22b) of said second tank (22) so that said upper wall (22a) is overlapped with said bottom wall (22b) of said second tank (22), and the other end of said third partition (53) inserts into the linear concave portions (64) of said upper wall (22a) and said bottom wall (22b) of said lower tank (22); and inserting opposite ends of said heat transfer tubes (24) into respective connection holes (40, 41) of said first tank (21) and said second tank (22). The method of claim 6 wherein said second number of chambers is one less than said first number of chambers. A method of manufacturing a heat exchanger as specified in claim 1, comprising the steps of: bending a plurality of planar raw plates to have an U-shaped cross section defining a flat portion and flange portions extending from both ends of said flat portion as an upper wall (121a, 122a) and a bottom wall (121b, 122b) of said first tank (121) and said second tank (122); opening a plurality of connection holes (40, 41) in said flat portion of said bottom wall (121b) of said first tank (121) and said upper wall (122a) of said second tank (122); forming concave portions (70-73) in said flat portion of said upper wall (121a) and said bottom wall (121b) of said first tank (121) substantially in cross shape; forming openings (70a, 71a) on top of said concave portion (70, 71); placing said upper wall (121a) of said first tank (121) on said bottom wall (121b) of said first tank (121) so that said upper wall (121a) is overlapped with said bottom wall (121b) of said first tank (121); inserting an end of said first partition (51) into said concave portion (72) of said bottom wall (121b) of said first tank (121) through said opening (70a); inserting a second partition (52) into said concave portion (73) of said bottom wall (121b) through said opening (71a) so that second partition (52) is substantially perpendicular to said first partition (51); forming linear concave portions (74, 75) on said flat portion of said upper wall (122a) and said bottom wall (122b) of said second tank (122); forming an opening (74a) on top of said concave portion (74); placing said upper wall (122a) of said second tank (122) on said bottom wall (122b) of said second tank (122) so that said upper wall (122a) is overlapped with said bottom wall (122b) of said second tank (122); inserting an end of said third partition (53) into said concave portion (75) of said bottom wall (122b) of said second tank (122) through said opening (74a); and inserting ends of said heat transfer tubes (24) into said respective connection holes (40, 41) of said first tank (121) and said second tank (122). A heat exchanger comprising: a first tank (21) including a plurality of connection holes (40), a first partition (51) and second partition (52) disposed therein to divide said first tank (21) into a first number of chambers, said first tank (21) respectively including an inlet (45) to allow a heat transfer medium to enter said heat exchanger and an outlet (46) to allow a heat transfer medium to exit said heat exchanger; a second tank (22) spaced from said first tank (21) and including a plurality of connection holes (41), and a third partition (53) disposed therein to divide said second tank (22) into a second number of chambers; a plurality of heat transfer tubes (24) fixedly disposed between said first tank (21) and said second tank (22) in fluid communication; said first tank (21) including a first concave portion (62) and a second concave portion (63) horizontally formed on a bottom wall (21b) of said first tank (21) and vertically projecting toward the outside of the upper tank (21), wherein ends of said first partition (51) and said second partition (52) respectively insert into said concave portions (62, 63) for preventing overturn of said first partition (51) and said second partition (52) during assembly of said first tank (21), said second tank (22) including a concave portion (65) U-shape in cross section horizontally formed on a bottom wall (22b) thereof and vertically projecting to the outside of the lower tank (22), wherein ends of said third partition (53) insert into said concave portion (65) for preventing overturn of said third partition (53) during assembly of said second tank (22); characterized in that said concave portions (62, 63) of said first tank (21) are substantially a cross in shape and said concave portion (65) of said second tank (22) are substantially linear in shape.

Inventors: MORITA TOMONARI, TSUNODA MASATAKA, MORITA, TOMONARI, TSUNODA, MASATAKA, MORITA, TOMONARI, C/O SANDEN CORPORATION, TSUNODA, MASATAKA, C/O SANDEN CORPORATION
Applicants: SANDEN CORP, SANDEN CORPORATION
Application year: 1995
Main classification: F28F9
IPC codes: F28D1, B21D53, F28F9