US20030106678A1

US20030106678A1 - Heat exchanger

Info

Publication number: US20030106678A1
Application number: US10/257,073
Authority: US
Inventors: Mutsumi Fukushima; Souichi Kato; Muneo Sakurada
Original assignee: Zexel Valeo Climate Control Corp
Current assignee: Valeo Thermal Systems Japan Corp
Priority date: 2000-04-10
Filing date: 2001-01-19
Publication date: 2003-06-12
Also published as: JP2001289535A; WO2001077591A1; EP1273858A1

Abstract

The upstream side ends of fins (16) along the ventilating direction project out relative to the upstream side ends along the ventilating direction of tubes (14) without being allowed to project out beyond the end faces of tanks (2) and (3) along the ventilating direction so as to set the tubes (14) at positions recessed toward the downstream side along the ventilating direction relative to the fins (16), and the downstream side ends of the fins (16) along the ventilating direction are recessed further toward the upstream side along the ventilating direction relative to the downstream side ends of tubes (15) along the ventilating direction. As a result, the evaporator achieves a lower profile along the ventilating direction and, at the same time, condensed water manifesting at the surfaces of the tubes and fins is drained downward with a high degree of efficiency, thereby minimizing occurrence of spattering of the condensed water onto the downstream side and also, it becomes possible to prevent corrosion from advancing at the tubes due to dirt adhering onto the upstream side of the tubes along the ventilating direction.

Description

TECHNICAL FIELD

P The present invention relates to a heat exchanger which may be utilized as, for instance, an evaporator in an air-conditioning system or the like for vehicles and, more specifically, it relates to a structure adopted in the fins of the heat exchanger.

BACKGROUND ART

An evaporator in the refrigerating cycle of an air-conditioning system for vehicles normally adopts a structure achieved by laminating tubes each having therein a coolant passage over a plurality of stages, providing a pair of tanks on the two sides along the lengthwise direction of the tubes to communicate with the coolant passages of the tubes and providing corrugated fins between the individual tubes so as to improve the heat exchanging efficiency, as disclosed in, for instance, Japanese Unexamined Patent Publication No. H 7-190661 or Japanese Unexamined Patent Publication No. H 8-17836.

In a heat exchanger adopting such a structure, the moisture in the air becomes condensed and condensed water is left on the surfaces of the tubes and fins while the tubes are cooled by the coolant which becomes evaporated as it flows through the tubes and the air passing between the tubes is cooled via the tubes and the fins. Then, the condensed water is spattered from the cooling heat exchanger due to the current of air from the air blower provided on the upstream side along the ventilating direction, which causes a problem of the condensed water moving into the cabin.

In addition, while a mesh filter or the like is normally provided on the upstream side of the heat exchanger along the ventilating direction to remove dirt mixed in the air taken in from the inside or the outside of the cabin, such a filter may be omitted in order to reduce production costs. In such a case, dirt moistened by the condensed water becomes adhered to the tubes and the presence of the moist dirt causes corrosion of the tubes.

At the same time, it is becoming increasingly important in recent years to improve the function of on-vehicle air-conditioning systems and to achieve further miniaturization and a further reduction in weight in order to effectively address issues such as environmental protection. For this reason, the evaporator constituting part of the refrigerating cycle in an air-conditioning system, too, must achieve a lower profile along the ventilating direction in the vehicle layout.

Accordingly, an object of the present invention is to provide a heat exchanger that is capable of draining condensed water from the surfaces of the tubes and fins alone the downward direction with a high degree of efficiency and preventing corrosion at the tubes caused by dirt adhering to the upstream side of the tubes along the ventilating direction from advancing while achieving a lower profile along the ventilating direction and can be utilized as an evaporator.

DISCLOSURE OF THE INVENTION

In order to achieve the object described above, a heat exchanger according to the present invention comprises, at least, tubes each having therein a heat exchanging medium passage, fins laminated alternately between the tubes and a tank provided at the ends of the tubes on at least one side, with the upstream side ends of the fins along the ventilating direction projecting further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes along the ventilating direction within a range in which the upstream side ends of the fins do not project beyond the upstream end face of the tank along the ventilating direction and the downstream side ends of the fins along the ventilating direction recessed toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes along the ventilating direction.

This structure, achieved by projecting in the upstream side ends of the fins along the ventilating direction further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes along the ventilating direction, does not readily allow dirt to reach the tubes provided at positions that are recessed toward the downstream side along the ventilating direction relative to the fins and thus, the risk of corrosion occurring at the tubes due to adhering dirt is reduced. In addition, since the upstream side ends of the fins along the ventilating direction do not project out further than the end face of the tank along the ventilating direction, the overall width of the heat exchanger along the ventilating direction does not increase, thereby making it possible to save space. Furthermore, the downstream side ends of the fins along the ventilating direction are recessed toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes along the ventilating direction. Thus, the condensed water having been caused to travel over the tubes or the fins to the downstream side along the ventilating direction by the air pressure is allowed to drop downward along the surfaces of the tubes located further toward the downstream side relative to the fins and spattering of the condensed water toward the downstream side is minimized.

Alternatively, the heat exchanger according to the present invention may comprise, at least, a plurality of tubes set in parallel to one another along the ventilating direction, which each include therein a heat exchanging medium passage, a plurality of fins set in parallel to one another along the ventilating direction and laminated alternately between the tubes with the quantity thereof made to correspond to the quantity of the tubes and a tank provided at the ends of the tubes on at least one side, with the upstream side end along the ventilating direction of a fin set on the side furthest upstream along the ventilating direction projecting out further toward the upstream side along the ventilating direction relative to the upstream side end along the ventilating direction of a tube set on the side furthest upstream along the ventilating direction within a range in which the upstream side end of the fin does not project beyond the upstream side end face of the tank along the ventilating direction and the downstream side end along the ventilating direction of a fin set on the side furthest downstream along the ventilating direction recessed further toward the upstream side along the ventilating direction relative to the downstream side end along the ventilating direction of the tube set on the side furthest downstream along the ventilating direction. The upstream side end along the ventilating direction of a fin which is not the fin set on the side furthest upstream along the ventilating direction, too, is made to project out further toward the upstream side along the ventilating direction relative to the upstream side end along the ventilating direction of the tube facing opposite the fin along the laminating direction within the range in which the upstream side end of the fin does not come in contact with the fin set further on the upstream side along the ventilating direction. In addition, the downstream side end along the ventilating direction of a fin which is not set on the side furthest downstream along the ventilating direction, too, is recessed further toward the upstream side along the ventilating direction relative to the downstream side end along the ventilating direction of each of tubes set in parallel to one another.

This structure, achieved by projecting the upstream side end along the ventilating direction of the fin set on the side furthest upstream along the ventilating direction further toward the upstream side along the ventilating direction relative to the upstream side end along the ventilating direction of the tube set on the side furthest upstream along the ventilating direction, does not readily allow dirt to reach the tube set at a position which is moved back further toward the upstream side along the ventilating direction relative to the fin so as to prevent the tube from becoming corroded due to dirt adhering thereto. In addition, since the upstream side end of the fin along ventilating direction does not project beyond the end face of the tank along the ventilating direction, the overall width of the heat exchanger along the ventilating direction does not increase, thereby meeting the space-saving requirement.

While condensation of water mainly occurs on the upstream side of the heat exchanger along the ventilating direction, the fins are provided in parallel to one another along the ventilating direction and, at the same time, the downstream side ends along the ventilating direction of the fins provided on the upstream side along the ventilating direction are recessed further toward the upstream side along the ventilating direction to form a gap from the fins on the downstream side along the ventilating direction so that condensed water manifesting along the upstream side along the ventilating direction is made to drop downward through the gap to drain the condensed water with an even higher degree of efficiency. Thus, it becomes possible to prevent the condensed water from moving onto the fins on the downstream side along the ventilating direction and to prevent the condensed water from becoming spattered onto the downstream side as well.

In addition, the upstream side ends along the ventilating direction of the fins are made to project out toward the upstream side along the ventilating direction by an extent greater than the extent by which the downstream side ends along the ventilating direction are recessed toward the upstream side along the ventilating direction.

This structure, in which the width of the fins along the ventilating direction is set greater than the width along the ventilating direction of the tubes facing opposite the fins along the laminating direction, allows the heat exchange with the air passing through the heat exchanger to be carried out with a higher degree of efficiency so as to improve the performance of the heat exchanger.

Furthermore, the tubes constituting the heat exchanger are each formed by bending a single brazing sheet with a junction formed by joining ends of the brazing sheet on the upstream side along the ventilating direction. The junction adopts a structure achieved by tightly winding the portion of the brazing sheet near one of the ends.

With the tubes taking on the structural features and the positional arrangement described above, the wall thickness of the tubes on the upstream side along the ventilating direction is increased through the tightly-wound structure. As a result, even if corrosion occurs at the tubes due to dirt escaping the fins projecting along the ventilating direction and becoming adhered to the tubes, the resistance against such corrosion is improved at the tubes themselves to lengthen the durability of the tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a perspective of the overall structure of a heat exchanger according to the present invention and an enlargement of its essential portion; [0016]
FIG. 2 presents a plan view showing the structure of the fins in the heat exchanger in FIG. 1 and the relationship of the fins to the tubes and the tanks; [0017]
FIG. 3 is a partial sectional view showing fins adopting a structure different from that in the heat exchanger shown in FIG. 1; and [0018]
FIG. 4 presents a plan view showing the structure of the fins in the heat exchanger in FIG. 3 and the relationship of the fins to the tubes and the tanks. [0019]

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in further detail in the following explanation given in reference to the attached drawings. [0020]
An evaporator [0021] 1 shown in FIGS. 1 and 2 is a laminated heat exchanger having tanks on the two sides thereof, which may be utilized in, for instance, the refrigerating cycle of an air-conditioning system for vehicles. The evaporator 1 is a two-path heat exchanger comprising a tank 2 provided at one end along its lengthwise direction, a tank 3 provided at an end on the opposite side from the tank 2, tubes 14 and 15 connected with the tank 2 and the tank 3 to communicate between the tank 2 and the tank 3, fins 16 laminated alternately over a plurality of stages between the tubes 14 and between the tubes 15 and end plates 17 and 17, each provided on either side along the laminating direction.
The [0022] tanks 2 and 3 are each constituted of an aluminum alloy cylindrical body 5 having connection holes 4 at which the tubes 14 and 15 are connected with the tank and blocking members 6 to be detailed below with the cylindrical body 5 formed as an integrated unit through extrusion molding.
This structure prevents leakage of the heat exchanging medium through a gap at a side of the tank formed due to incomplete bonding of a deep-drawn tank member and a blocking member in a tank in the related art constituted of the deep-drawn tank member roughly formed in a bowl shape with one end thereof left open and the blocking member blocking off the opening. In addition, problems such as freezing rupture caused by condensed water entering an area of the junction where the members are not completely brazed and thus where pinholes and the like are formed, can be avoided as well. [0023]
While the [0024] tank 2 is a turn-around tank having the openings on the two sides thereof each blocked with a blocking plate 6, which allows the heat exchanging medium to turn around, the tank 3 is an intake/outlet tank that includes an intake portion 8 and an outlet portion 9 completely isolated from each other by a barrier plate 7 extending at the center within the cylindrical body 5 along the direction in which the tubes 14 and 15 are laminated, with the openings at the intake portion 8 and the outlet portion 9 on each side blocked by inserting two blocking plates 6 through mounting holes 11 formed in the cylindrical body 5.
The [0025] barrier plate 7 at the tank 3, formed as an integrated part of the cylindrical body 5 through extrusion molding, prevents any deterioration in the performance of the evaporator 1, which may otherwise be caused by the heat exchanging medium allowed to directly travel between the intake portion and the outlet portion through a gap created due to incomplete bonding of a barrier plate constituted as a separate member and the tank internal circumferential surface. In addition, an intake pipe 12 is connected continuous to an end of the intake portion 8 and an outlet pipe is connected continuous to an end of the outlet portion 9.
It is to be noted that since the evaporator [0026] 1 is operated in an environment in which it is in contact with water at all times, a sacrificial layer is formed at the surfaces of the tanks 2 and 3 by thermal-spraying zinc (Zn) onto the surfaces or by forming a layer containing zinc on the surfaces which are extruded through two-layer extrusion, so as to improve anticorrosion performance.
As shown in FIG. 2, the [0027] tubes 14 and 15 are each formed by bending a single brazing sheet over a plurality of stages through roll-forming or press-machining, and each tube 14 or 15 includes a heat exchanging medium passage 20 enclosed by a pair of flat surfaces 18 and 18 extending along the ventilating direction and a flat surface 19 located on the downstream side along the ventilating direction and extending along the laminating direction. In addition, on the upstream side along the ventilating direction of each of the tubes 14 and 15, a tightly-wound structure is achieved by tightly winding the portion of the brazing sheet near one end, thereby forming a tightly-wound portion 21 and by forming a contact portion 22 at the other end of the brazing sheet to come into contact with the base end of the tightly-wound portion 21 and a blocking portion 23 continuous to the contact portion 22 to close the downstream side opening of the heat exchanging medium passage 20.
By setting the [0028] tubes 14 and 15 parallel to each other so as to place the tightly-wound portions 21, the contact portions 22 and the blocking portions 23 each set thereof constituting the tightly-wound structure on the upstream side along the ventilating direction, the wall thickness of the tubes 14 and 15 on the upstream side along the ventilating direction is increased. As a result, the resistance against corrosion occurring as a result of particles of dirt or the like traveling from the upstream side along the ventilating direction and becoming adhered to the tubes can be improved to increase the durability of the tubes 14 and 15.
It is to be noted that while [0029] inner fins 24 are housed inside the individual heat exchanging medium passages 20 as shown in FIG. 2 so as to improve the mixability of the heat exchanging medium in the embodiment, a plurality of beads may also be formed on the inside of the surfaces extending perpendicular to the ventilating direction (not shown) as well for the same purposes. Furthermore, the tubes 14 and 15 may instead each be formed through extrusion molding or they may each be formed by bonding face-to-face two formed plates to each other, and tubes formed through extrusion molding may each include a plurality of heat exchanging medium passages.
The [0030] fins 16 provided between the tubes 14 and 14 and between the tubes 15 and 15, or between the tubes 14, 15 and the end plates 17 are each formed as a single-piece corrugated fin in this embodiment. The upstream side ends of the fins are made to project out further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes 14 along the ventilating direction by a specific extent a in alignment with the end face of the tank 3 along the ventilating direction (in alignment with the end of the tank 2 as well although not shown). The downstream side ends of the fins 16 along the ventilating direction are recessed further toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes 15 along the ventilating direction by a specific extent b, as shown in FIG. 2.
The measurement of the specific extent a by which the [0031] fins 16 project out is set larger than the measurement of the specific extent b by which the fins 16 are recessed and, as a result, the dimension of the fins 16 along the ventilating direction is larger than the dimension between the downstream side end of a tube 14 along the ventilating direction and the upstream side end of the corresponding tube 15 along the ventilating direction.
By adopting this structure in the [0032] fins 16, the upstream side end surfaces of the tubes 14 along the ventilating direction are set at positions recessed relative to the fins 16 along the ventilating direction and thus, even if no air filter is provided on the upstream side of the evaporator 1 along the ventilating direction, any dirt present in the air taken in from the inside and the outside of the cabin is captured at the fins 16 and is not allowed to reach the tubes 14 readily, thereby making it possible to protect the tubes 14 from corrosion caused by dirt adhered thereto. Furthermore, since the fins 16 are only allowed to project out on the upstream side along the ventilating direction to the upstream side end faces of the tanks 2 and 3 along the ventilating direction at the most, the width of the evaporator 1 along the ventilating direction does not increase compared to the width of evaporators in the related art, in keeping with the space-saving requirement which necessitates the size of the evaporator 1 to be kept as small as possible.
In addition, since the downstream side ends of the [0033] fins 16 along the ventilating direction are recessed further toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes 15 along the ventilating direction, condensed water having been caused by the air pressure to move over the tubes 15 or the fins 16 to the downstream side along the ventilating direction is allowed to drop downward from the evaporator along the surfaces of the tubes 15. Furthermore, since the dimension of the fins taken along the ventilating direction is greater than the dimension of fins 16 in the prior art, the efficiency with which heat is exchanged with the passing air improves as well.
However, the present invention is not limited to the example described above in which a [0034] single fin unit 16 is provided between the tubes and instead, a plurality of fins may be provided parallel to one another along the ventilating direction between the tubes. Now, in reference to FIGS. 3 and 4, an embodiment achieved by providing two fins 16 parallel to each other along the ventilating direction is explained. The same reference numerals are assigned to structural features identical to those in the embodiment shown in FIGS. 1 and 2 to preclude the necessity for a repeated explanation thereof.
As in the case with the [0035] fins 16 in the previous embodiment, the upstream side ends along the ventilating direction of the fins 16 set on the upstream side along the ventilating direction project out further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes 14 along the ventilating direction by a predetermined extent a without projecting beyond the end face of the tank 3 along the ventilating direction at the most (also without projecting beyond the end face of the tank 2 along the ventilating direction, although not shown) in the embodiment. Also, the upstream side ends along the ventilating direction of the fins 16 set on the downstream side along the ventilating direction project out further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes 15 along the ventilating direction without reaching the downstream side ends of the tubes 14 along the ventilating direction. It is to be noted that the extent by which the fins 16 on the downstream side along the ventilating direction project out relative to the tubes 15 should be set equal to the extent a by which the fins on the upstream side along the ventilating direction project out relative to the tubes 14.
In addition, as in the case with the [0036] fans 16 in the previous embodiment, the downstream side ends along the ventilating direction of the fins 16 located on the downstream side along the ventilating direction are recessed by a specific extent b toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes 15 along the ventilating direction. Also, the downstream side ends along the ventilating direction of the fins 16 on the upstream side along the ventilating direction are recessed further toward the upstream side along the ventilating direction relative to the downstream side ends of the fins 14 along the ventilating direction. It is desirable that the extent by which the fins 16 on the downstream side along the ventilating direction are recessed relative to the downstream side ends of the tubes 15 along the ventilating direction be equal to the extent b by which the fins on the upstream side along the ventilating direction are recessed relative to the downstream side ends of the tubes 14 along the ventilating direction.
By adopting the structure described above achieved by providing a plurality of [0037] fins 16 parallel to one another, the upstream side end faces of the tubes 14 along the ventilating direction are set at positions recessed relative to the fins 16 on the upstream side along the ventilating direction and thus, even if no air filter is provided on the upstream side of the evaporator 1 along the ventilating direction, any dirt present in the air taken in from the inside and the outside of the cabin is captured at the fins 16 and is not allowed to reach the tubes 14 readily, thereby making it possible to protect the tubes 14 from corrosion caused by dirt adhered thereto. Furthermore, since the fins 16 are only allowed to project out on the upstream side along the ventilating direction to the upstream side end faces of the tanks 2 and 3 along the ventilating direction at the most, the width of the evaporator 1 along the ventilating direction does not increase compared to the width of evaporators in the related art, in keeping with the space-saving requirement which necessitates the size of the evaporator 1 to be kept as small as possible.
Moreover, while condensation of water occurs on the upstream side of the evaporator [0038] 1 along the ventilating direction, the downstream side ends along the ventilating direction of the fins 16 provided on the upstream side along the ventilating direction are recessed further toward the upstream side along the ventilating direction to form a desirable gap from the fins 16 on the downstream side along the ventilating direction so that condensed water having been caused by the air pressure to move over the surfaces of the fins 16 on the upstream side along the ventilating direction is allowed to drop downward through the gap to reliably drain the condensed water. Thus, it becomes possible to prevent the condensed water from moving onto the fins 16 on the downstream side along the ventilating direction and to prevent the condensed water from becoming spattered onto the downstream side as well.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention in which the upstream side ends along the ventilating direction of the fins project out further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes along the ventilating direction, dirt is not allowed to readily reach the tubes set at positions recessed toward the downstream side along the ventilating direction relative to the fins and, as a result, the risk of corrosion occurring at the tubes due to adhering dirt can be reduced. Furthermore, since the upstream side ends of the fins along the ventilating direction do not project out further beyond the end faces of the tanks along the ventilating direction, the width of the heat exchanger along the ventilating direction does not increase in keeping with the space-saving requirement. Moreover, since the downstream side ends of the fins along the ventilating direction are recessed toward the upstream side along the ventilating direction relative to the downstream side ends of the tubes along the ventilating direction, condensed water having been caused by the air pressure to move over the tubes or the fins to the downstream side along the ventilating direction can be drained in a downward direction along the surfaces of the tubes located further toward the downstream side relative to the fins to minimize the occurrence of spattering of the condensed water onto the downstream side along the ventilating direction. [0039]
In addition, according to the present invention in which the upstream side ends along the ventilating direction of the fins provided on the upstream side along the ventilating direction project out further toward the upstream side along the ventilating direction relative to the upstream side ends of the tubes along the ventilating direction, dirt is not allowed to readily reach the tubes set at positions recessed toward the upstream side along the ventilating direction relative to the fins and, as a result, the risk of corrosion occurring at the tubes due to adhering dirt can be reduced. Furthermore, since the upstream side ends of the fins along the ventilating direction do not project out further beyond the end faces of the tanks along the ventilating direction, the width of the heat exchanger along the ventilating direction does not increase in keeping with the space-saving requirement. Moreover, while condensation of water occurs on the upstream side of the heat exchanger [0040] 1 along the ventilating direction, the downstream side ends along the ventilating direction of the fins provided on the upstream side along the ventilating direction are recessed further toward the upstream side along the ventilating direction to form a desirable gap from the fins provided on the downstream side along the ventilating direction so that condensed water having been caused by the air pressure to move over the surfaces of the fins on the upstream side along the ventilating direction is allowed to drop downward through the gap to reliably drain the condensed water. Thus, it becomes possible to prevent the condensed water from moving onto the fins on the downstream side along the ventilating direction and to prevent the condensed water from becoming spattered onto the downstream side as well.
Furthermore, according to the present invention, the width of the fins along the ventilating direction is greater than the width along the ventilating direction of the tubes facing opposite the fins along the laminating direction. Thus, the efficiency with which heat exchange is achieved through the fins is improved to achieve higher heat exchanging efficiency in the heat exchanger. [0041]
Moreover, according to the present invention, the wall thickness of the tubes on the upstream side along the ventilating direction is increased by adopting a tightly-wound structure and thus, even if corrosion occurs due to dirt escaping the fins projecting out along the ventilating direction and reaching the tubes to become adhered thereto, the resistance against such corrosion is improved to lengthen the durability of the tubes. [0042]

Claims

1. A heat extender comprising, at least, tubes each having therein a heat exchanging medium passage, fins laminated alternately between said tubes and a tank provided at ends of said tubes on at least one side, characterized in that:

upstream side ends along the ventilating direction of said fins project out further toward the upstream side along the ventilating direction relative to upstream side ends of said tubes along the ventilating direction within a range in which the upstream side ends of said fins do not further beyond an end face of said tank on the upstream side along the ventilating direction; and

downstream side ends of said fins along the ventilating direction are recessed further toward the upstream side along the ventilating direction relative to downstream side ends of said tubes along the ventilating direction.

2. A heat exchanger comprising, at least, tubes each having therein a heat exchanging medium passage, with a plurality thereof set parallel to one another along the ventilating direction, fins laminated alternately between said tubes with a plurality thereof set parallel to one another along the ventilating direction in a quantity corresponding to the quantity of said tubes and a tank provided at ends of said tubes on one side, characterized in that:

an upstream side end along the ventilating direction of a fin set on a side furthest upstream along the ventilating direction project out further toward the upstream side along the ventilating direction relative to an upstream side end along the ventilating direction of a tube set on the side furthest upstream along the ventilating direction within a range in which the upstream side end of said fin along the ventilating direction does not project further beyond an end face of said tank on the upstream side along the ventilating direction; and

a downstream side end along the ventilating direction of a fin set on a side furthest downstream along the ventilating direction is recessed further toward the upstream side along the ventilating direction relative to a downstream side end along the ventilating direction of a tube set on the side furthest downstream along the ventilating direction.

3. A heat exchanger according to claim 2, characterized in that:

an upstream side end along the ventilating direction of a fin that is not the fin set on the side furthest upstream along the ventilating direction, too, projects out further toward the upstream side along the ventilating direction relative to an upstream side end along the ventilating direction of a tube facing opposite said fin along the laminating direction within a range in which the upstream side end of said fin does not come into contact with the fin set on the side furthest upstream along the ventilating direction.

4. A heat exchanger according to claim 2, characterized in that:

a downstream side end along the ventilating direction of a fin that is not the fin set on the side furthest downstream along the ventilating direction, too, is recessed further toward the upstream side along the ventilating direction relative to the downstream side ends along the ventilating direction of said tubes set in parallel to one another.

5. A heat exchanger according to claim 1, 2, 3 or 4, characterized in that:

the extent by which the upstream side ends of said fins along the ventilating direction project out further toward the upstream side along the ventilating direction is greater than the extent by which the downstream side ends along the ventilating direction of said fins are recessed further toward the upstream side along the ventilating direction.

6. A heat exchanger according to claim 1, 2, 3 or 4, characterized in that:

said tubes are each formed by bending a single brazing sheet; and

said tubes each include a junction formed by bonding ends of said brazing sheet on the upstream side along the ventilating direction and said junction assumes a structure achieved by tightly winding a portion of said brazing sheet close to one of the ends.