Laminated heat exchanger with a single tank structure

Abstract: A laminated heat exchanger with a single tank structure, of the type which does not have its fin holding portions in contact, but rather facing opposite each other over a specific gap, is provided, which ensures that the fins do not extend out of the gaps between the fin holding portions. The laminated heat exchanger has a single tank structure provided with tube elements constituted with tank portions formed by distending at one end in the direction of its length and fin holding portions formed by bending at the other end in the direction of its length. Tanks are constituted on one side of the core by bonding adjacent tube elements. On the opposite side from the tanks the positions at which the fin holding portions face opposite over a specific gap are shifted toward one side by a specific distance from the central position of the width of the lamination between the adjacent tube elements over a hole at the center in the direction of the width.

Description: The present invention relates to a laminated heat exchanger with a single tank structure comprising the features according to the preamble of claim 1. Such a heat exchanger is used mainly in air conditioning systems in motor vehicles. Heat exchangers of this type in the prior art include a heat exchanger provided with tube elements which are each constituted with a tank portion formed by distension at one end in the direction of the length and a fin holding portion at the other end in the direction of the length formed by bending in which the tube elements are laminated to constitute tanks on one side of the heat exchanger core. The fin holding portions for holding fins are in contact on the opposite side from the tanks of the heat exchanger core. (Refer to, for instance, Japanese Examined Patent Publication No. H4-34080) In this prior art, since the heat exchanger is structured to have the fin holding portions in contact on the opposite side from the tanks in the heat exchanger core, when brazing the heat exchanger, the brazing material tends to flow into the contact area and this causes a problem in that there may be insufficient brazing material in the other areas. Because of this, in typical heat exchangers now, the fin holding portions are not put into contact with each other but instead are made to face each other with a gap of specific dimension between them. However, with the type of heat exchanger in the prior art described above, in which the fin holding portions in adjacent tube elements are not in contact but are positioned facing opposite each other with a gap of specific dimension between them, a problem arises that, during assembly of the heat exchanger, fins tend to extend out of the gaps between the fin holding portions and to become pinched. In addition, even when the heat exchanger is assembled without the fins extending out, the fins can still be pushed out due to misalignment of the core. When fins become extended out of the gaps between the fin holding portions in this manner, difficulty in adding the lining may result and also problems such as lowered performance, running out of brazing material and the like may occur. In U.S. Patent No. 4723601 there is provided an evaporator having core plates provided with bent end portions including joint surfaces which abut one another. The bent end portions also include a single projection and a single recess. The engagement between the projection and recess of adjacent core plates prevents the core plates sliding relative to each other in the direction of the planes of the plates. The object of the present invention is to provide a laminated heat exchanger with a single tank structure in which the fin holding portions are not in contact, facing each other with gaps of specific dimension between them and the fins are prevented from extending out of the gaps between the fin holding portions by addressing the problems described earlier. The preamble of claim 1 of the present invention is based upon U.S. Patent No. 4723601. According to the present invention there is provided a laminated heat exchanger comprising: a plurality of tube elements (1), each of which comprises a pair of tank portions (2,2) formed at one end in a longitudinal direction thereof and a heat exchanging medium passage (25) communicating between said pair of tank portions (2,2); the tank portions constituting tank passages; wherein by bonding and laminating the tank portions (2,2) of said adjacent tube elements (1), a heat exchanger core with a single tank structure is formed, in which a tank (30) is constituted in the lower area, fins (3) are inserted between the tube elements (1), an end plate (4) at one end and an end plate (5) at the other end in the direction of the lamination is provided and a passage plate (8) with a supply passage (6) and a discharge passage (7) for the heat exchanging medium is provided in one of the end plates (4) characterized in that: a pair of fin holding portions (22,23) extending in the direction of lamination are formed at the opposite side from the tank portions of said tube element (1), said pair of fin holding portions (22,23) being formed each side in the direction of lamination of said tube elements (1), one of said fin holding portions (22) at one side in the direction of lamination being formed as longer than a half of the height (L3) of said fins (3), another of said fin holding portions (23) at one side in the direction of lamination being formed as shorter than half the height (L3) of said fins (3), one of said fin holding portions (22) of one tube element of said two adjacent tube elements (1) and another of said fin holding portions (23) of another tube element of said two adjacent tube elements as well as another of said fin holding portions (23) of one tube element of said two adjacent tube elements (1) and one of said fin holding portions (22) of another tube element of said two adjacent tube elements facing one another, a specific gap (L0) is formed between one of said fin holding portions (22) of one tube element of said two adjacent tube elements (1) and another of said fin holding portions (23) of another tube element of said two adjacent tube elements as well as another of said fin holding portions (23) of one tube element of said two adjacent tube elements (1) and one of said fin holding portions (22) of another tube element of said two adjacent tube elements. The laminated heat exchanger with a single tank structure according to the present invention may also be provided with an extended portion at the end of one of the fin holding portions that face opposite each other in order to cover the other fin holding portion. Consequently, according to the present invention, since the positions at which the fin holding portions face opposite each other are off-set, the fins are, at least, constantly connected and held by the fin holding portions. The fins are thereby prevented from extending out of the gaps between the fin holding portions. Moreover, by providing an extended portion at one end of one of the fin holding portions that face opposite each other to cover the other fin holding portion, the gap between the fin holding portions facing opposite each other, is covered from the outside and as a result, the gap into which the fin could otherwise extend is blocked off, thereby preventing them even more effectively from extending out. Figure 1 is a schematic structural diagram of the heat exchanger according to the present invention; Figure 2 is a side view of the heat exchanger according to the present invention; Figure 3 is a perspective view of a formed plate that constitutes the tube element; Figure 4 is a functional diagram illustrating the flow of the heat exchanging medium; Figures 5 and 6 illustrate the structure in which the fin holding portions face opposite each other in the first embodiment of the present invention; Figures 7 and 8 illustrate the structure in which the fin holding portions face opposite each other in the second embodiment of the present invention; Figure 9 is a perspective of a laminated heat exchanger in the prior art that employs a structure in which the fin holding portions face opposite each other, and Figure 10 is a perspective of a formed plate used in the laminated heat exchanger above. The following is an explanation of the embodiments according to the present invention in reference to the drawings. Figures 1 and 2 show an example of the heat exchanger according to the present invention. This heat exchanger is provided with corrugated fins 3 laminated alternately with tube elements 1 over a plurality of levels, each of which is provided with a tank portion 2, an end plate 4 at one end, an end plate 5 at the other end in the direction of the lamination, and a passage plate 8 with a supply passage 6 and a discharge passage 7 for the heat exchanging medium which is provided in one of the end plates 4. The supply passage 6 and the discharge passage 7 of the passage plate are attached to an intake pipe 10 and an outlet pipe 11 for heat exchanging medium respectively. Each tube element 1 is constituted by bonding flush two of the formed plates 15 shown in Figure 3. Each formed plate 15 is rectangular in shape and is provided with a pair of indented portions for tank formation 18 and 19 formed by distending at one end of plate 15 in the direction of length, with through holes 16 and 17 respectively, and a projection 20 projecting out from between the indented portions for tank formation 18 and 19 toward the other end. It is also provided with an approximately U-shaped indented portion for heat exchanging medium passage formation 21 which is formed by distending and which communicates with the indented portions for tank formation 18 and 19 and is located on the peripheral edge of the projection 20. A notch 24 for passing a heat exchanging medium supply pipe 38 to be explained later, is provided between the indented portions for tank formation 18 and 19. On the other end of this formed plate 15 in the direction of its length, a pair of fin holding portions 22 and 23 for holding the fins 3 are formed by bending toward the outside by individually specific lengths. A tube element 1 is constituted by bonding two formed plates 15 that are structured as described above, flush to each other. At one end of the tube element a pair of tank portions 2, 2 are constituted by the indented portions for tank formation 18 and 19 which face opposite each other and, at the same time, a heat exchanging medium passage 25 which is roughly U-shaped is constituted on the inside by the indented portions for heat exchanging medium passage formation 21 which face opposite each other. The heat exchanging medium passage 25 communicates with the tank portions 2, 2. By bonding and laminating the tank portions 2, 2 of such adjacent tube elements 1, 1, a heat exchanger core with a single tank structure is formed, in which a tank 30 is constituted in the lower area and fins 3 are inserted between the tube elements 1 (refer to Figure 1). As shown in Figure 4, the heat exchanger structured as described above has a so-called 4-pass flow pattern, in which heat exchanging medium that is supplied via a heat exchanging medium intake 36 at a joint 35 of a block expansion valve 37, flows to the supply passage 6 of the passage plate 8 via the expansion valve 37, through a heat exchanging medium supply pipe 38 which is connected to the supply passage 6. It then reaches a tank passage 39, which is constituted by the tank portions 2, which communicate at the front on the right side. From the tank passage 39, it flows inside the heat exchanging medium passage 25 of each tube element that communicates with the tank passage 39, to reach a tank passage 40 which is constituted by the tank portions 2 that communicate at the rear on the right side. It then moves horizontally within the tank passage 40 to reach the tank passage 41, which is constituted by tank portions 2 that communicate at the rear on the left side. From the tank passage 41 it flows inside the heat exchanging medium passage 25 of each tube element that communicates with the tank passage 41 to be collected in a tank passage 42, which is constituted by tank portions 2 communicating at the front on the left side. During this process, heat exchanging with the outside air is accomplished. The heat exchanging medium gathered in the tank passage 42 travels through the discharge passage 7 of the passage plate 8 to be discharged through the heat exchanging medium outlet 43 of the joint 35 via the block expansion valve 37. As shown in Figures 5 and 6, on the opposite side from the tank 30 in this heat exchanger, the fin holding portions 22 of each tube element 1 face opposite each other over a specific gap distance L0. Note that since the tube elements 1 used here are identical, the fin holding portions 22 and 23 face opposite each other in such a manner that symmetry is achieved from left to right. The fin holding portion 22 has an oblong shape so that the length of its bend L1 is at least half the height L3 of the fin 3. The fin holding portion 23 has an oblate shape so that the length of its bend L2 is less than half the height L3 of the fin 3. In addition, the positions at which the fin holding portions 22, 23 face opposite each other are made to be closer toward one side by a specific distance LB from the central position of the width of the lamination LA between adjacent tube elements 1 across a space 24 at the center in the direction of the width. In other words, they are off-set. The positions at which the fin holding portions face opposite each other is offset by a specific distance from the central position of the width of the lamination between adjacent tube elements 1 across the space 24 at the center in the direction of the width so that the fins 3 can be prevented from extending out to the outside of the gap between the fin holding portions 22, 23 with the linear fins 3 connected and held by at least one of the fin holding portions 22, 23. When the lengths of the bends of the fin holding portions that face opposite each other are different, and the positions where they face each other (LA + LB) are offset toward the outside from the center (LA), the ends of the linear fins 3 become connected and held by at least one of the fin holding portions 22, 23 and this will prevent the fins 3 from extending out from the gaps. Note that the positions where the fin holding portions face opposite each other (LA + LB), i.e., the lengths of the bends L1, L2 of the fin holding portions 22, 23, can be selected as appropriate through experiment. Next, the structure in which the fin holding portions face opposite each other according to the second specified invention, is explained in reference to Figures 7 and 8. The structure in which the fin holding portions face opposite each other in the second specified invention differs from that in the first specified invention described earlier in that an extended portion 45 extends at the end of one 22 of the holding portions 22, 23. All the other setting aspects are identical to those in the first specified invention explained earlier. The extended portion 45 extends at the center at the end of the fin holding portion 22, and as shown in Figures 7 and 8, it is set in such a manner that it covers the other fin holding portion 23. By extending the extended portion 45 at the end of one fin holding portion 22, to cover the other fin holding portion 23, the gap between the fin holding portions 22, 23 into which the fin 3 could otherwise extend, is blocked off. As a result, in addition to the advantages achieved with the heat exchanger according to the first specified invention, the fins 3 are even more effectively prevented from extending out. In other words,being covered from the outside, the gap between the fin holding portions 22, 23 is blocked off and the fins 3 do not have any room to extend into. Note that, while in the embodiment described above, the extended portion 45 is formed toward the fin holding portion 22 with the longer bend, the extended portion 45 may be provided toward the fin holding portion 23 with the shorter bend and similar advantages will be achieved. Also, while the embodiments described so far are constituted by concentrating the intake pipe and the outlet pipe at one of the end plates and attaching the block expansion valve 37, as shown in Figures 2 and 4, the present invention may also be applied to currently used heat exchangers, including heat exchangers provided with intake / outlet pipes 10, 11 with openings formed toward the front of the heat exchanger, as shown in Figures 9 and 10. This heat exchanger is constituted by laminating tube elements that are formed by butting formed plates 15 flush to each other, each of which is provided with indented portions for tank formation 18 and 19 on one side in the direction of the length, as shown in Figure 10, a projection 20 extending from between the indented portions for tank formation 18 and 19 and a U-shaped passage 21, alternately with fins 3. This formed plate 15, too, is also provided with a pair of fin holding portion 22, 23 for holding the fins which are formed at the other end in the direction of its length by bending toward the outside with specific and different lengths of bends. Because of this, the position at which the fin holding portions face opposite each other can be set non-linearly. Note that the same reference numbers are assigned to the all other components that are identical to those in the previous embodiments and their explanation is omitted. As has been explained, in the laminated heat exchanger with a single tank structure according to the present invention, the positions at which the fin holding portions that hold the fins face opposite each other on the opposite side from the tanks are off-set to reliably prevent the fins from extending out. Consequently, defective assembly of the heat exchanger can be prevented. In addition, in the laminated heat exchanger with a single tank structure provided with the extended portion at one of the pair of fin holding portions that face opposite each other to cover the other fin holding portion, the gap between the fin holding portions that face opposite each other is blocked off. As a result, in addition to the advantages described earlier, the extending out of the fin ends can be even more reliably prevented.

Claims: A laminated heat exchanger comprising: a plurality of tube elements (1), each of which comprises a pair of tank portions (2,2) formed at one end in a longitudinal direction thereof and a heat exchanging medium passage (25) communicating between said pair of tank portions (2,2); the tank portions constituting tank passages (39,40,41,42); wherein by bonding and laminating the tank portions (2,2) of said adjacent tube elements (1), a heat exchanger core with a single tank structure is formed, in which a tank (30) is constituted in the lower area, fins (3) are inserted between the tube elements (1), an end plate (4) at one end and an end plate (5) at the other end in the direction of the lamination is provided and a passage plate (8) with a supply passage (6) and a discharge passage (7) for the heat exchanging medium is provided in one of the end plates (4) characterized in that: a pair of fin holding portions (22,23) extending in the direction of lamination are formed at the opposite side from the tank portions of said tube element (1), said pair of fin holding portions (22,23) being formed each side in the direction of lamination of said tube elements (1), one of said fin holding portions (22) at one side in the direction of lamination being formed as longer than a half of the height (L3) of said fins (3), another of said fin holding portions (23) at one side in the direction of lamination being formed as shorter than half the height (L3) of said fins (3), one of said fin holding portions (22) of one tube element of said two adjacent tube elements (1) and another of said fin holding portions (23) of another tube element of said two adjacent tube elements as well as another of said fin holding portions (23) of one tube element of said two adjacent tube elements (1) and one of said fin holding portion (22) of another tube element of said two adjacent tube elements facing one another, a specific gap (LO) is formed between one of said fin holding portions (22) of one tube element of said two adjacent tube elements (1) and another of said fin holding portions (23) of another tube element of said two adjacent tube elements as well as another of said fin holding portions (23) of one tube element of said two adjacent tube elements (1) and one of said fin holding portions (22) of another tube element of said two adjacent tube elements. A laminated heat exchanger according to claim 1, characterized in that an intake pipe (10) communicates with one of said supply passage (6) and substantially communicates with one of said tank passages (39) via a heat exchanging medium supply pipe (38) communicating with said supply passage (6), and an outlet pipe (11) communicates with another of said tank passages (41) via said discharge passage (7). A laminated heat exchanger according to claim 1, characterized in that said intake pipe (10) is in direct communication with one of the tank portions (2) constituting one of said tank passages (39), and said outlet pipe (11) is in direct communication with one of the tank portions (2) constituting another of said tank passages (40). A laminated heat exchanger according to claim 1, 2 or 3, characterized in that said tube element (1) is formed by bonding two formed plates (15) facing each other, each of said formed plates (15) comprises a pair of indented portions for tank formation (18,19) formed at one end in longitudinal direction thereof, a projection (20) extending from between said pair of indented portions for tank formation (18,19) in the longitudinal direction and an indented portion for heat exchanging medium passage formation (21), and said pair of fin holding portions (22,23) are formed at another end of the longitudinal direction in said formed plate (15) by extending to projecting direction of said indented portions for tank formation (18,19) and said indented portion for heat exchanging medium passage formation (21). A laminated heat exchanger according to one of any preceding claims, characterized in that one of said fin holding portions (22,23) has an extended portion (45), said extended portion extending from said one of said fin holding portions (22,23) to contact with another of said fin holding portions (22,23) which said one of said fin holding portions (22,23) faces. A laminated heat exchanger according to claim 5, characterized in that said extended portion (45) is formed at the longer fin holding portion (22). A laminated heat exchanger according to one of any preceding claims, characterized in that a space (24) is formed between said pair of fin holding portions (22,23) of two adjacent tube elements (1).

Inventors: NISHISHITA KUNIHIKO C O ZEXEL, NISHISHITA KUNIHIKO C/O ZEXEL CORP. KONAN FACTORY
Applicants: ZEXEL CORP, ZEXEL CORPORATION
Application year: 1995
Main classification: F28D1
IPC codes: F28F3, F28D1