Heat exchanger

Abstract

A heat exchanger has tubes for performing heat exchange between an internal fluid flowing inside of the tubes and an external fluid flowing outside of the tubes and a tank connected to the tubes. Each of the tubes has projections projecting from an outer surface thereof. The projections are arranged in a longitudinal direction of the tube such that grooves are provided between the adjacent projections as external fluid passage portions. The tank has tube insertion portions defining openings into which ends of the tubes are inserted. Each of the tube insertion portions is configured such that a perimeter surface defining the opening thereof entirely covers at least one external fluid passage portion of the tube.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2006-181260 filed on Jun. 30, 2006, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger that has tubes defining external fluid passages on outer surfaces thereof and a tank connected to ends of the tubes.

BACKGROUND OF THE INVENTION

A heat exchanger that has tubes defining grooves on its outer surfaces as external fluid passage portions is for example disclosed in Unexamined Japanese Patent Publication No. 2004-3787 (U.S. Pat. No. 6,595,273). In the heat exchanger, each of the tubes is constructed of a pair of plate members. Each plate member has a base wall portion and projections projecting from the base wall portion. The plate members are joined such that the projections project outwardly.

The projections extends in a serpentine or meandering manner in a direction perpendicular to a longitudinal direction of the tube. The grooves are provided between the adjacent projections as the external fluid passage portions through which an external fluid (e.g., air) flows. Because the external fluid flows through the grooves in the meandering manner, the flow of the air is disturbed. This structure suppresses a growth of a temperature boundary layer adjacent to the outer surface of the tube, and improves coefficient of heat transfer on the outer surface of the tube.

Also, the plate members are joined to make contact with each other at the external fluid passage portions, i.e., bottom walls of the grooves, and internal fluid passages through which an internal fluid (e.g., refrigerant) flows are formed between the plate members. In this structure, the external fluid passage portions also serve as inner pillars for improving the resistance to pressure of the tube.

Further, ends of the tubes are inserted in tube insertion holes of tanks and the outer surfaces of the tubes are joined (e.g., brazed) with perimeter surfaces that define the tube insertion holes. In this case, however, if the grooves are disposed over the perimeter surfaces of the tube insertion holes with respect to a longitudinal direction of the tube, an inside space of the heat exchanger will be communicated with an outside of the heat exchanger through the grooves. This results in leakage of the internal fluid through the grooves.

Also, it may be considered to form the tubes such that the grooves as the external fluid passage portions are not formed at the ends of the tubes. In this case, the outer surface of the end of the tube will be joined with the perimeter surface of the tube insertion hole without having a large clearance. However, since the external fluid passage portions, which also serve as the inner pillars, are not formed at the ends of the tubes, the resistance to pressure will be reduced at the ends of the tubes.

Japanese Unexamined Patent Publication No. 2001-133189 discloses a heat exchanger having tubes without having grooves as external fluid passage portions on outer surfaces thereof and a tank. In the tank, plural tank members are layered such that opening thereof are aligned and thus tube insertion holes are provided by the openings. Since the tank members are thin, the openings are easily formed. This publication is addressed to ease forming of the tube insertion holes in the heat exchanger having the tubes that do not have the grooves on the outer surfaces thereof. This publication does not teach how to form the tube insertion holes for receiving the ends of the tubes having the external fluid passage portions in order to restrict leakage of the internal fluid through the internal fluid passage portions at all.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing matter, and it is an object of the present invention to provide a heat exchanger having a connecting structure between ends of tubes and tube insertion portions of a tank, which is capable of reducing leakage of an internal fluid through external fluid passage portions of the tubes.

According to an aspect of the present invention, a heat exchanger has a plurality of tubes for performing heat exchange between an internal fluid flowing inside of the tubes and an external fluid flowing outside of the tubes and a tank connected to ends of the tubes. Each of the tubes has projections that project from an outer surface thereof. The projections are arranged in a longitudinal direction of the tube such that grooves are provided between the adjacent projections as external fluid passage portions for allowing the external fluid to flow. The tank has a plurality of tube insertion portions defining openings in which ends of the tubes are inserted. Each of the plurality of tube insertion portions is configured such that a perimeter surface defining the opening thereof entirely covers at least one groove of the end of the tube.

Namely, at least one external fluid passage portion at the end of the tube is entirely covered by the perimeter surface of the tube insertion portion. In other words, the external fluid passage portion disposed in the opening of the tube insertion portion does not extends over the perimeter surface of the tube insertion portion. This structure restricts an inner space of the heat exchanger from communicating with an outside of the heat exchanger through the external fluid passage portion in the tube insertion portion. Accordingly, it is less likely that the internal fluid will leak through the external fluid passage portion in the tube insertion portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

FIG. 1 is a schematic plan view a heat exchanger according to a first embodiment of the present invention;

FIG. 2 is a schematic perspective view of a portion of a heat exchanging part of the heat exchanger according to the first embodiment;

FIG. 3 is a schematic perspective view of a portion of a tube of the heat exchanger according to the first embodiment;

FIG. 4 is a schematic perspective view of a portion of a tank of the heat exchanger according to the first embodiment;

FIG. 5 is an exploded perspective view of the portion of the tank according to the first embodiment;

FIG. 6 is a schematic cross-sectional view of a portion of the tank according to the first embodiment;

FIG. 7 is a schematic cross-sectional view of the portion of the tank in which the tube is inserted according to the first embodiment;

FIG. 8 is a schematic cross-sectional view of a portion of a heat exchanger according to a second embodiment of the present invention;

FIG. 9 is a schematic cross-sectional view of a portion of a heat exchanger according to a third embodiment of the present invention;

FIG. 10 is a schematic cross-sectional view of a portion of a heat exchanger according to a fourth embodiment of the present invention;

FIG. 11 is a schematic cross-sectional view of a portion of a heat exchanger according to a fifth embodiment of the present invention;

FIG. 12 is a perspective view of a tubular member of the heat exchanger according to the fifth embodiment; and

FIG. 13 is a schematic cross-sectional view of a portion of a heat exchanger according to a sixth embodiment of the present invention

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

First Embodiment

A first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

Referring to FIG. 1, a heat exchanger 10 is for example used as a refrigerant condenser of a refrigerating cycle for a vehicle air conditioner. The heat exchanger 10 is mounted in an engine compartment of a vehicle, at a position where outside air is sufficiently supplied while the vehicle is running. An up and down arrow in FIG. 1 denotes an exemplary arrangement direction of the heat exchanger 10 in the vehicle.

The heat exchanger 10 performs heat exchange between a high temperature, high pressure refrigerant as an internal fluid, which has been discharged from a compressor (not shown) of the refrigerating cycle, and the air as an external fluid, thereby condensing the refrigerant. The heat exchanger 10 generally has a heat exchanging part 13 and tanks 14, 15, as shown in FIG. 1.

The heat exchanging part 13 includes a plurality of flat tubes 11 and a plurality of fins 12. The tubes 11 define refrigerant passages (internal fluid passages) therein through which the refrigerant flows. The fins 12 are for example corrugated fins. The tanks 14, 15 are located at longitudinal ends 11a, 11b of the tubes 11. The longitudinal ends 11a, 11b of the tubes 11 are inserted in openings of tube insertion portions 14d, 15d of the tanks 14, 15.

The tanks 14, 15 are provided to distribute and collect the refrigerant into and from the tubes 11. Each of the tanks 14, 15 includes a first tank member 14a, 15a, a second tank member 14b, 15b and caps 14c, 15c. The first tank member 14a, 15a has a generally semi-tubular shape. Also, the second tank member 14b, 15b has a generally semi-tubular shape. The first tank member 14a, 15a and the second tank member 14b, 15b are connected to each other such that the tank 14, 15 has a generally tubular shape. The caps 14c, 15c cover longitudinal ends of the tanks 14, 15.

For example, each of the first tank members 14a, 15a, the second tank members 14b, 15b and the caps 14c, 15c is made of a metal plate (e.g., aluminum material). A surface of the metal plate, which corresponds to an inner surface of the tank 14, 15, is coated with a brazing material (filler material), and the metal plate is formed into a predetermined shape by pressing.

The tank 14 has a refrigerant inlet portion 14e at an end (e.g., lower end in FIG. 1) thereof. Although not illustrated, an inlet pipe is coupled to the refrigerant inlet portion 14e for introducing the high pressure, high temperature refrigerant discharged from the compressor into the heat exchanger 10.

The tank 15 has a refrigerant outlet portion 15e at an end (e.g., upper end in FIG. 1) thereof. Although not illustrated, an outlet pipe is coupled to the refrigerant outlet portion 15e for discharging a liquid-phase refrigerant from the heat exchanger 10 toward an expansion valve of the refrigerating cycle.

At the ends of the heat exchanging part 13, side plates 16, 17 are provided to maintain a rectangular-shaped outline of the heat exchanger 10. The side plates 16, 17 are disposed parallel to the tubes 11 and ends of the side plates 16, 17 are connected to the ends of the tanks 14, 15. The tubes 11, the fins 12, and the tanks 14, 15 are joined by integrally brazing, for example.

Referring to FIGS. 2 and 3, each of the tubes 11 is constructed of a pair of plate members 18, 19. For example, the plate members 18, 19 are thin plate-like members made of an aluminum material, and both surfaces of the thin plate members are coated with a brazing material.

Each of the plate members 18, 19 includes a flat base wall 20 and a plurality of projections 21 projecting from the flat base wall 20. The plate members 18, 19 are paired such that the projections 21 project in opposite directions and the base walls 20 have surface contact. Also, the plate members 18, 19 are arranged such that portions between the projections 21 overlap with each other. Thus, refrigerant passages 22 through which the refrigerant flows are formed between the paired plate members 18, 19.

Each of the projections 21 projects from the base wall 20 at a substantially middle position with respect to a tube width direction D2, which is perpendicular to a tube longitudinal direction D1. The projection 21 has a flat wall on its top and curved side walls 23, which face in the tube longitudinal direction D1. Each of the side walls 23 of the projection 21 extends in the tube width direction D2 in a serpentine or meandering manner.

The projections 21 are arranged at a regular pitch P in the tube longitudinal direction D1 such that clearances are provided between the adjacent projections 21, i.e., the side walls 23 of the adjacent projections 21 as grooves. Namely, the grooves having a serpentine shape are formed between the adjacent projections 21 on outer surfaces of the tubes 11. The grooves serve as air passage portions (external fluid passage portions) 24 for allowing the air in a serpentine or meandering manner.

A bottom wall of the air passage portion 24 includes a flat wall 24c and first and second recessed portions 24a, 24b that are recessed from the flat wall 24c toward an inside of the tube 11 through step portions 24d, 24e. For example, the first recessed portions 24a are formed at position corresponding to peaks or most curved portions of the serpentine shaped air passage portion 24 and the second recessed portions 24b are formed at position corresponding to the end of the air passage portion 24. The first and second recessed portions 24a, 24b are provided by the base wall 20. In other word, the first and second recessed portions 24a, 24b are on the same level as the base wall 20. The flat wall 24c slightly project from the base wall 20 toward an outside of the tube 11.

Also, the air passage portions 24 of the plate members 18, 19 are staggered in the tube longitudinal direction D1, but the first and second recessed portions 24a, 24b of the plate member 18 overlap with the first and second recessed portions 24a, 24b of the plate member 19. Thus, the plate members 18, 19 are in contact with and joined with each other at the first and second recessed portions 24a, 24b. In this embodiment, the step portions 24d, 24e have height approximately 0.65 mm, respectively.

In the tube 11, the refrigerant passage 23 has a complex serpentine shape as shown by arrows B in FIG. 2. Since the air passage portions 24 of the two plate members 18, 19 are staggered in the tube longitudinal direction D1, the refrigerant passage 23 extends in the tube longitudinal direction D1 while meandering in a direction in which a height of the tube 11 is measured (i.e., in an up and down direction in FIG. 2).

Further, since the first recessed portions 24a of the two plate members 18, 19 are overlapped and joined with each other, the refrigerant passage 23 diverges at the first recessed portions 24a and merges downstream of the first recessed portions 24a. As such, the refrigerant passage 23 extends in the tube longitudinal direction D1 while repetitively diverging and merging in the tube width direction D2. Namely, the refrigerant passage 23 is formed in a serpentine manner both in the tube longitudinal direction D1 and in the tube width direction D2.

As shown in FIG. 2, the fins 12 are made of a bare plate without coated by a brazing material. The bare plate is for example made of an aluminum material and is formed into a corrugated shape.

Each of the fin 12 includes joining portions 12a, 12b to be joined with the flat top wall of the projections 21 and connecting walls 12c, 12d connecting the joining portions 12a, 12b. The joining portions 12a, 12b are flat walls. The connecting walls 12c, 12d are flat walls and extend in a tube stack direction in which the tubes 11 are stacked (i.e., up and down direction in FIG. 2). Although not illustrated, the connecting walls 12c, 12d are formed with louvers that are formed by cutting portions of the connecting walls 12c, 12d and angling the cut portions so as to oppose the flow of air.

Next, an effect of heat exchange between the refrigerant and the air in the heat exchanging part 13 will be described. As shown by the arrows B in FIG. 2, since the refrigerant flows inside of the tubes 11 while meandering complexly, the flow of the refrigerant is disturbed. As such, the coefficient of heat transfer of the refrigerant improves. Accordingly, efficiency of heat transfer improves.

On the other hand, the air that flows through areas separated from the tubes 11 flows along the fins 12, as shown by an arrow C in FIG. 2. This air receives heat from the fins 12 and then flows out of the fins 12. Thus, the fins 12 are cooled by the air passing through the fins 12.

Also, the air that flows adjacent to the tubes 11 receives heat from the tubes 11 and is discharged from the heat exchanging part 13 after cooling the tubes 11. In this case, as the air flows through the air passage portions 24 in the serpentine manner, as shown by an arrow D in FIG. 2, the flow of this air is disturbed. As such, the coefficient of heat transfer of the air improves. Accordingly, efficiency of heat transfer improves.

In addition, as the air is contracted when flowing into the air passage portions 24, the coefficient of heat transfer of the air improves. Further, because the surface area of heat transfer is increased by the air passage portions 24, the amount of heat radiation from the tube 11 to the air is increased.

Furthermore, the flow of air is further disturbed by the step portions 24d, 24e of the air passage portions 24. With this, the coefficient of heat transfer of the air further improves.

Next, connecting structure of the tanks 14, 15 and the tubes 11 will be described with reference to FIGS. 4 to 7. The connecting structure of the tank 14 and the tubes 11 are the same as the connecting structure of the tank 15 and the tubes 11. In FIGS. 4 to 7, therefore, component parts regarding the tank 15 are indicated by numerals in parentheses.

The first tank member 14a, 15a is a member to be joined with the tubes 11. The first tank member 14a, 15a includes a flat wall 25, 26 that extends in a direction perpendicular to the tube longitudinal direction D1, i.e., in a direction parallel to a tank longitudinal direction D3. A plate 27, 28, having a substantially rectangular shape, is brazed to the flat wall 25, 26. The plate 27, 28 is made of an aluminum material, and a surface of the plate 27, 28 facing the first tank member 14a, 15a is coated with a brazing material (filler material).

As shown in FIGS. 5 and 6, the flat wall 25, 26 of the first tank member 14a, 15a is formed with first hole portions 29, 30. The first hole portions 29, 30 of the first tank member 14a, 15a define oblong or oval-shaped openings. The plate 27, 28 is formed with second hole portions 31, 32 defining oblong or oval-shaped openings.

Specifically, the plate 27, 28 includes a main wall portion defining openings and tubular portions 31a, 32a on peripheries of the openings of the main wall portion, as the second hole portions 31, 32. The tubular portions 31a, 32a project in an outward direction of the tank 14, 15 and in a direction parallel to the tube longitudinal direction D1. Each of the tubular portions 31a, 32a has an oval shape in a cross-section defined in a direction perpendicular to the tube longitudinal direction D1. The tubular portion 31a, 32a is formed by burring a periphery of the opening of the main wall portion.

The plate 27, 28 is disposed on the flat wall 25, 26 such that the openings of the second hole portions 31, 32 are aligned with the openings of the first hole portions 29, 30. Thus, the openings of the tube insertion portions 14d, 15d are provided by the openings of the first and second hole portions 29, 30, 31, 32, as shown in FIG. 6. In other words, a perimeter surface (perimeter portion) defining the opening of each tube insertion portion 14d, 15d is provided by a surface that defines the opening of the first hole portion 29, 30 and a surface that defines the opening of the second hole portion 31, 32.

Here, the tubular portion 31a, 32a has a length L2 in the tube longitudinal direction D1. A length L of the perimeter surface of the tube insertion portion 14d, 15d in the tube longitudinal direction D1 is defined by a total dimension of a wall thickness t1 of the flat wall 25, 26 of the first tank member 14, 15 and the length L2 of the tubular portion 31a, 32a. (L=t1+L2) In this embodiment, the length L is equal to or greater than the pitch P of the projections 21 of the tubes 11.

As shown in FIG. 7, in a condition that the longitudinal end 11a, 11b of the tube 11 is inserted in the opening of the tube insertion portion 14d, 15f, the outer surfaces of the tube 11 is joined to the perimeter surface of the opening of the tube insertion portion 14d, 15d by brazing.

Further, the longitudinal end 11a, 11b of the tube 11 is inserted in the opening of the tube insertion portion 14d, 15d such that an area shown by chain double-dashed lines in FIG. 3 overlaps with the perimeter surface of the tube insertion portion 14, 15. Namely, as shown in FIGS. 3 and 7, the perimeter surface of the tube insertion portion 14, 15 entirely covers one air passage portion 24 on each of the plate members 18, 19.

As such, the air passage portion 24 does not extend over the perimeter surface of the tube insertion portion 14d, 15d. Therefore, this connecting structure restricts communication between an inside space and an outside space of the heat exchanging part 13 through the air passage portions 24. Accordingly, it is less likely that the refrigerant will leak outside of the heat exchanging part 13 through the air passage portions 24.

Since the tubular portion 31a, 32a is formed by burring, the length L of the perimeter surface of the tube insertion portion 14d, 15d is increased. As such, the air passage portion 24 of the longitudinal end 11a, 11b of the tube 11 is entirely covered by the perimeter surface of the tube insertion portion 14d, 15d.

Also, the tube insertion portion 14d, 15d is constructed by aligning the first hole portion 29, 30 of the first tank member 14a, 15a with the second hole portion 31, 32 of the plate 27, 28. Therefore, a thin plate member can be used as the plate member 27, 28.

Since the plate member 27, 28 are provided by the thin plate member, the tubular portions 31a, 32a are easily formed, as compared with a case of forming the tubular portions on a thick plate member. Accordingly, the tube insertion portions 14d, 15d are easily formed. Further, the tubular portions 31a, 32a are easily formed on the thin plate member by burring.

Since the length L of the perimeter surface of the tube insertion portion 14d, 15d is equal to or greater than the pitch P of the projections 21 of the tube 11, at least one air passage portion 24 is entirely covered by the perimeter surface of the tube insertion portion 14d, 15d, irrespective of a positional relation between the tube 11 and the tank 14, 15 with respect to the tube longitudinal direction D1.

As a result, the leakage of the refrigerant through the air passage portion 24 is restricted without being affected by the positional relation between the tube 11 and the tank 14, 15 with respect to the tube longitudinal direction D1. In other words, the leakage of the refrigerant through the air passage portion 24 is restricted without being affected by assembling accuracy of the tube 11 to the tank 14, 15 with respect to a tube inserting direction.

In fact, the longer the length L of the perimeter surface is, the more securely the leakage of the refrigerant through the air passage portion 24 is restricted. However, the length L is longer than necessary as shown by a chain double-dashed line in FIG. 7, the plural air passage portions 24 of each plate member 18, 19 are covered by the perimeter surface. This may results in a decrease in an effect of improving the heat transfer coefficient of the air. Therefore, it is necessary to consider this matter.

Second Embodiment

A second embodiment of the present invention will be described with reference to FIG. 8. As shown in FIG. 8, tubular portions 29a, 30a are formed on the peripheries of the openings of the first hole portions 29, 30 of the first tank member 14a, 15a. Thus, the tube insertion portion 14d, 15d is provided by the tubular portion 29a, 30a of the first tank member 14a, 15a and the tubular portion 31a, 32a of the plate 27, 28. The tubular portions 29a, 30a project inside of the tank 14, 15. The tubular portions 29a, 30a are formed by burring.

The perimeter portion of the tube insertion portion 14d, 15d is provided by an inner surface of the tubular portion 31a, 32a of the first tank member 14a, 15a and the inner surface of the tubular portion 29a, 30a of the plate 27, 28. The length L of the perimeter portion of each tube insertion portion 14d, 15d is defined by a total of a length L1 of the tubular portion 29a, 30a of the first tank member 14a, 15a and the length L2 of the tubular portion 31a, 32a of the second hole portion 31, 32. (L=L1+L2)

In this case, the length L is increased greater than the length L of the first embodiment shown in FIG. 7. Therefore, the communication between the inside space of the heat exchanging part 13 and the outside space is more securely restricted. As such, the leakage of the refrigerant through the air passage portion 24 is further effectively restricted.

In this case, the tubular portions 29a, 30a of the first tank member 14a, 15a project inside of the tank 14, 15. Namely, the tubular portions 29a, 30a does not overlap with the air passage 24 outside of the tank 14, 15. Therefore, it is less likely that the coefficient of heat transfer of the air will be affected by the tubular portions 29a, 30a of the first tank member 14a, 15a. The length L of the perimeter surface is increased without reducing the coefficient of heat transfer of the air of the air passage portions 24.

If the length L1 of the tubular portion 29a, 30a is longer than necessary as shown by a chain double-dashed line in FIG. 8, the flow of the refrigerant inside of the tank 14, 15, the flow of the refrigerant distributed into the tubes 11 from the tank 14, the flow of the refrigerant collected into the tank 15 from the tubes 11 will be disturbed by such the long tubular portions 29a, 30a. This may results in a decrease in the heat exchanging efficiency of the heat exchanger 10. Therefore, it is necessary to consider this matter.

Third Embodiment

A third embodiment of the present invention will be described with reference to FIG. 9. As shown in FIG. 9, a second plate 33, 34 is added to the structure shown in FIG. 6. The second plate 33, 34 has third hole portions 35, 36 defining ova-shaped openings and is arranged along an inner surface of the flat wall 25, 26 of the first tank member 14a, 15a such that the openings of the third hole portions 35, 36 are aligned with the openings of the first hole portions 29, 30 of the first tank member 14a, 15a and the openings of the second hole portion 31, 32 of the plate (hereafter, referred to as first plate) 27, 28. Namely, the tube insertion portion 14d, 15d is provided by the first hole portion 29, 30, the second hole portion 31, 32 and the third hole portion 35, 36.

In this embodiment, the second plate 33, 34 for example has a rectangular shape and extends in the tank longitudinal direction D3. The second plate 33, 34 is brazed to the inner surface of the first tank member 14a, 15a. Namely, the second plate 33, 34 is disposed on a side opposite to the first plate 27, 28 with respect to the flat wall 25, 26 of the first tank member 14a, 15a.

The second plate 33, 34 is provided by a plate member made of an aluminum material and a surface of the plate member facing the first tank member 14a, 15a is coated with a brazing material (filler material). In the above description, the second plate 33, 34 is the rectangular shaped plate. However, the second plate 33, 34 may be provided by a semi-tubular shaped plate to extend over the entire inner surface of the first tank member 14a, 15a.

In this embodiment, the length L of the perimeter surface of the tube insertion portion 14d, 15d defined by a total dimension of the wall thickness t1 of the first tank member 14a, 15a, the length L2 of the tubular portion 31a, 32a and a wall thickness t3 of the second plate 33, 34. (L=t1+L2+t3)

Accordingly, the length L is increased greater than the length L of the first embodiment. Therefore, the communication of the inside space of the heat exchanging part 13 with the outside space through the air passage portion 24 is further restricted. As such, the leakage of the refrigerant through the air passage portion 24 is further restricted.

Fourth Embodiment

A fourth embodiment will be described with reference to FIG. 10. In the third embodiment, the second plate 33, 34 is formed with a tubular portion 35a, 36a, and thus the third hole portion 35, 36 is provided by an opening of the tubular portion 35a, 36a. The tubular portion 35a, 36a projects inside of the tank 14, 15. The tubular portion 35a, 36b is formed by burring. The tube insertion portion 14d, 15d is provided by the tubular portions 31a, 32a, 35a, 36a of the second and third hole portions 31, 32, 35, 36 and the first hole portion 29, 30.

In this embodiment, the length L of the perimeter surface of the tube insertion portion 14d, 15d is defined a total dimension of the wall thickness t1 of the first tank member 14a, 15a, the length L2 of the tubular portion 31a, 32a and a length L3 of the tubular portion 35a, 36a. (L=t1+L2+L3)

Accordingly, the length L of the perimeter surface of the tube insertion portion 14d, 15d is increased greater than the length L of the third embodiment. Therefore, the leakage of the refrigerant through the air passage portion 24 is further effectively restricted.

Fifth Embodiment

A fifth embodiment will be described with reference to FIGS. 11 and 12. In the fifth embodiment, the opening of the tube insertion portion 14d, 15d is provided by an opening of a tubular member 37, 38.

As shown in FIG. 12, the tubular member 37, 38 includes a tubular wall portion 37a, 38a defining an opening and an annular flange portion 37b, 38b radially expanding from an end of the tubular wall portion 37a, 38a. The flange portion 37b, 38b are integrally formed with the tubular wall portion 37a, 38a. For example, the tubular member 37, 38 is made of an aluminum material and is coated with a brazing material (filler material).

The tubular member 37, 38 is inserted into the opening of the first hole portion 29, 30 from the outside of the tank 14, 15, so that the flange portion 37b, 38b contacts the flat wall 25, 26 of the first tank member 14a, 15a. The flange portion 37b, 38b is joined to the flat wall 25, 26 of the first tank member 14a, 15a.

In this case, the perimeter surface of the tube insertion portion 14d, 15d is provided by the inner surface of the tubular member 37, 38. The length L of the perimeter surface of the tube insertion portion 14d, 15d is defined by a length L4 of the tubular member 37, 38. (L=L4)

Also in this case, the leakage of the refrigerant through the air passage portion 24 is restricted, similar to the first embodiment.

Sixth Embodiment

A sixth embodiment will be described with reference to FIG. 13. As shown in FIG. 13, the opening of the tube insertion portion 14d, 15d is provided by the opening of the first hole portion 29, 30 of the first tank member 14a, 15a and the opening of the tubular wall portion 37a, 38a of the tubular member 37, 38.

In the sixth embodiment, the tubular wall portion 37a, 38a is not inserted in the opening of the first hole portion 29, 30. Instead, the flange portion 37b, 38b is disposed along the inner surface of the first tank member 14a, 15a such that the opening of the tubular member 37, 38 and the opening of the first hole portion 29, 30 are aligned. The flange portion 37b, 38b is joined with the inner surface of the first tank member 14a, 15a.

The perimeter surface of the tube insertion portion 14d, 15d is provided by the inner surface of the tubular member 37, 38 and the surface defining the opening of the first hole portion 29, 30. The length L of the perimeter surface is defined by a total dimension of the wall thickness t1 of the first tank member 14a, 15a and the length L4 of the tubular member 37, 38. (L=t1+L4)

Also in this case, the leakage of the refrigerant through the air passage portion 24 is restricted, similar to the fifth embodiment.

Modifications

In the first embodiment, the tubular portion 31a, 32a is formed on the plate 27, 28 and the perimeter surface of the tube insertion portion 14d, 15d is provided by the inner surface of the tubular portion 31a, 32a and the surface defining the opening of the first hole portion 29, 30. However, it is not always necessary that the plate 27, 28 has the tubular portion 31a, 32a. For example, the wall thickness of the plate 27, 28 and the first tank member 14a, 15a may be increased and thus the perimeter surface of the tube insertion portion 14d, 15d may be provided by the surface defining the opening of the first hole portion 29, and an inner surface of an opening of the plate 27, 28. Also in this case, at least one air passage 24 of the tube 11 is entirely covered by the perimeter surface of the tube insertion portion 14d, 15d.

In the above embodiments, the opening of the tube insertion portion 14d, 15d is constructed by aligning the openings of the plural tank members 14a, 15a, 27, 28, 33, 34, 37, 38. Alternatively, the opening of the tube insertion portion 14d, 15d may be formed by an opening of a single member. For example, in the first embodiment shown in FIGS. 4 to 7, the plate 27, 28 can be eliminated and the opening of the tube insertion portion 14d, 15d is provided only by the opening of the first hole portion 29, 30. In this case, a tubular portion may be formed on a periphery of the opening of the first hole portion 29, 30 of the first tank member 14a, 15a to project in the direction parallel to the tube longitudinal direction D1, instead of the tubular portion 31a, 32a of the plate 27, 28.

In the above embodiments, the air passage portions 24 are grooves extending in the tube width direction D2 in the serpentine manner. However, the shape of the air passage portions 24 is not limited to the serpentine shape. For example, the air passage portions 24 may be straight grooves extending obliquely with respect to the tube width direction D2.

In the above embodiments, each tube 11 is constructed of the pair of plate members 18, 19 both having the projections 21. However, the structure of the tube 11 is not limited to the above. For example, only one of the plate members 18, 19 may have the projections 21. Also, the tube 11 may be provided by a cylindrical tube or a flat tube formed by extrusion. When the tube 11 is formed by the extrusion, the grooves as the air passage portions 24 are formed on the outer surfaces of the tube 11 by pressing the tube 11 from the outside.

In the above embodiments, the tube insertion portion 14d, 15d has the oblong or oval-shaped opening. However, the shape of the opening of the tube insertion portion 14d, 15d is not limited to the above. The opening of the tube insertion portion 14d, 15d may have any shape so as to correspond to an external cross-sectional shape of the tube 11.

In the above first to fourth embodiments, the shape of the plate 27, 28 is not limited to the generally rectangular shape. For example, the plate 27, 28 may have a semi-tubular shape to correspond to the entire inner surface of the first tank member 14a, 15a.

The heat exchanger 10 is not limited to the refrigerant condenser. The heat exchanger 10 may be any heat exchangers used for various purposes.

The example embodiments of the present invention are described above. However, the present invention is not limited to the above embodiments, but may be implemented in other ways without departing from the spirit of the invention.

Claims

1. A heat exchanger comprising:

a plurality of tubes for performing heat exchange between an internal fluid flowing inside of the tubes and an external fluid flowing outside of the tubes, each of the tubes having projections that project from an outer surface thereof, the projections arranged in a longitudinal direction of the tube such that grooves are provided between the adjacent projections as external fluid passage portions for allowing the external fluid to flow; and

a tank including a plurality of tube insertion portions defining openings in which ends of the tubes are disposed, wherein

each of the tube insertion portions is configured such that a perimeter surface defining the opening thereof entirely covers at least one external fluid passage portion of the end of the tube.

2. The heat exchanger according to claim 1, wherein

the plurality of projections are arranged at a regular pitch in the longitudinal direction of the tube, and

the perimeter surface of the opening of the tube insertion portion has a length equal to or greater than the pitch of the projections with respect to the longitudinal direction of the tube.

3. The heat exchanger according to claim 1, wherein

each of the tube insertion portions includes a tubular portion that projects in a direction parallel to the longitudinal direction of the tube,

the tubular portion has an inner surface and defines an opening at least as a portion of the opening of the tube insertion portion, and

the inner surface of the tubular portion is included in the perimeter surface of the opening of the tube insertion portion.

4. The heat exchanger according to claim 3, wherein the tubular portion projects outside of the tank.

5. The heat exchanger according to claim 3, wherein the tubular portion projects inside of the tank.

6. The heat exchanger according to claim 3, wherein the tubular portion is formed by burring.

7. The heat exchanger according to claim 3, wherein

the tank has a plurality of tank members each defining a plurality of openings, the plurality of tank members are disposed such that the openings thereof are aligned with each other and the openings of the tube insertion portions are provided by the openings of the tank members,

the tubular portions are provided by at least one of the tank members, and

the perimeter surface of the opening of each tube insertion portion is provided by the inner surface of the tubular portion and a surface that defines the opening of the remaining tank member.

8. The heat exchanger according to claim 3, wherein

the tank has a tank member defining a plurality of openings and tubular members each defining an opening,

the tank member and the tubular members are joined with each other such that the openings of the tubular members correspond to the openings of the tank member, and the opening of each tube insertion portion is provided by one opening of the tank member and the opening of one tubular member, and

the tubular portions are provided by the tubular members.

9. The heat exchanger according to claim 1, wherein

the tank has a plurality of tank members each defining a plurality of openings,

the plurality of tank members are disposed such that the openings thereof are aligned with each other and provide the openings of the tube insertion portions, and

the perimeter surface of the opening of each tube insertion portion is provided by surfaces that define the openings of the tank members.