WO2002035170A1

WO2002035170A1 - Heat exchanger

Info

Publication number: WO2002035170A1
Application number: PCT/JP2001/009326
Authority: WO
Inventors: Hiroyasu Shimanuki; Ryoichi Hoshino; Noboru Ogasawara; Takashi Tamura; Takashi Terada; Futoshi Watanabe; Hirofumi Horiuchi
Original assignee: Showa Denko K.K.
Priority date: 2000-10-25
Filing date: 2001-10-24
Publication date: 2002-05-02
Also published as: AU2002212677A1

Abstract

In a heat exchanger comprising a hollow header (2) and a plurality of heat exchanging tubes (1) which are in fluid communication with the header (1), the cross-sectional shape of the header (2) is formed into an angular cross-sectional shape including a rectangular cross-sectional shape and a square cross-sectional shape. Furthermore, the inner space of the header (2) is divided into a plurality of collecting chambers (13) by header-partitioning walls (12) provided in the header (2), and that the inner surface (14) of the tube-non-connecting-side wall in the collecting chamber (13) is formed into a curved surface. As a result, the inner volume of the header (2) can be reduced greatly as compared with that of the conventional header while securing sufficient pressure resistance and lightweight. Furthermore, the heat exchanger can be further miniaturized and the amount of the refrigerant to be used can be reduced. Furthermore, a heat exchanger having an excellent heat conducting characteristic and small refrigerant flow resistance can be obtained.

Description

DESCRIPTION

HEAT EXCHANGER

Cross Reference to Related Applications

This application is an application filed under 35 U.S.C. §111 (a) claiming the benefit pursuant to 35 T-J.S..C. § 119 (e) (1) of the filing data of Provisional Application No .60/306, 465 filed July 20, 2001 pursuant to 35 U. S . C. § 111 (b) .

Technical Field

The present invention relates to a heat exchanger, and more particularly, to a heat exchanger suitably used as a condenser or an evaporator for use in air-conditioning systems such as car air-conditioning systems or room air-conditioning systems.

Background Art

For example,^' in a condenser for use in air-conditioning systems, it is required to miniaturize the condenser while improving the heat-conducting characteristic as well as decreasing the refrigerant flow resistance. Especially, in a car air- conditioning condenser, it is strongly required to further miniaturize it because of a limited mounting space. Furthermore, it is also strongly required to decrease the amount of refrigerant to be used in view of earth environment protection. In order to meet these requirements, it is an important object to miniaturize the condenser by reducing the inner volume thereof.

In order to attain these objects, as shown in Figs. 13A and 13B, the so-called multi-pass type heat exchanger 100, which has a pair of round headers 101 and 101 and a plurality of heat exchanging tubes 102 with opposite ends thereof connected to. the headers, is widely used. In this multi-pass type condenser, since the header 101 is round in horizontal cross-section, the condenser is excellent in pressure resistant . Furthermore, since a plurality of tubes 102 are arranged in parallel each other, the flow resistance of refrigerant can be decreased, enabling the use of tubes having smaller cross-section, which enables to enlarge the heat- transfer-area density (surface area per unit volume) . As a result, it becomes possible to provide a condenser miniaturized as required for a car air-conditioner and decrease the inner volume of the tube, which in turn can decrease the refrigerant amount to be used.

Although the inner volume of the tube can be decreased as mentioned above, the decreased inner volume of the tube inevitably causes an increased ratio of the header inner volume to the entire refrigerant circuits. Thus, in order to further miniaturize the condenser and further decrease the inner volume thereof, it is important to decrease not only the inner volume of the tube but also that of the header.

In cases where a round cross-sectional shape is adopted as a cross-sectional shape of the header 101 as mentioned above, it is necessary to secure the diameter of the header 101 large enough to allow an insertion of an end portion of the tube 102. As a result, the maximum width ( ) of the header 101 in the longitudinal direction of the tube 102 increases inevitably, which makes it difficult to further decrease the inner volume of the header 101.

On the other hand, some heat exchangers employ a header having an approximately elliptical cross-sectional shape, which can decrease the inner volume of the header. In this case, however, it is required to increase the thickness of the header so as to secure sufficient strength against the inner pressure, resulting in increased weight of header, which in turn makes it difficult to provide a lightweight heat exchanger.

It is an object of the present invention to provide a heat exchanger which can decrease inner volume of a header while securing enough strength against inner pressure and lightweight, which in turn can miniaturize the entire heat exchanger body, reduce the amount of refrigerant to be used and meet the request of earth environment protection.

It is another object of the present invention to provide a heat exchanger which is excellent in heat-conducting characteristic and small in refrigerant flow resistance.

Other objects and advantages of the present invention will be apparent from the following preferred embodiments. Disclosure of Invention

According to the present invention, a heat exchanger comprises a hollow header and a plurality of heat exchanging tubes which are in fluid communication with the hollow header, wherein the header has an angular cross-sectional shape including a rectangular cross-sectional shape and a square cross-sectional shape, wherein the header is provided with one or a plurality of header-partitioning walls extending in a longitudinal direction of the header, whereby an inner space of the header is divided into a plurality of collecting chambers, and wherein a tube-non- connecting-side wall of each of the collecting chambers has a curved inner surface.

Since the header has not a conventional round cross-sectional shape but an angular cross-sectional shape including a rectangular cross-sectional shape and a square cross-sectional shape, it becomes possible to design such that the width S of the header is smaller than the depth T of the header, resulting in decreased inner volume of the header. As a result, the entire heat exchanger can be effectively miniaturized and the amount of refrigerant to be used can be decreased. Furthermore, the header is provided with one or a plurality of header-partitioning walls extending in a longitudinal direction of the header, whereby an inner space of the header is divided into a plurality of collecting chambers. Accordingly, the reinforcing effect against inner pressure can be obtained, resulting in sufficient pressure resistance of the header. In a conventional elliptical cross-sectional shape of a header, it is required to increase the thickness of the header to secure enough pressure resistance. To the contrary, in the present invention, it is not required to increase the thickness of the header, resulting in a lightweight header. Furthermore, since a tube- non-connecting-side wall of each of the collecting chambers has a curved inner surface, it is effectively prevented the refrigerant flowed out of the end portion of the tube from returning to the end portion of the tube even if the refrigerant collided against the inner surface of the tube-non-connecting-side wall of the header and rebounded therefrom. Thus, the refrigerant rebounded from the inner surface will be gathered in the central portion of each collecting chamber without interfering with the refrigerant flowed out of the end portion of tube and then flow downward in the header. In the collecting chamber, it is preferable that a maximum distance from an end of the tube communicated with the collecting chamber to the curved inner surface of the tube-non-connecting-side wall is 2 mm or more and 80% or less of a width of the tube. This effectively reduces the inner volume of the header while increasing the flow-down velocity of the liquefied refrigerant in the header.

It is preferable that the curved inner surface is provided with a plurality of vertically extending refrigerant-guiding grooves. This enhances the prompt flow-down and discharge of the liquid refrigerant. It is preferable that a communication opening is formed in the header-partitioning wall at the same height as a height of a tube-connecting position of the header. This communication opening allows the liquefied refrigerant in each collecting chamber to be mixed with each other . Thus, larger accumulation of liquefied refrigerant in a windward-side collecting chamber can be prevented, resulting in even accumulation of liquefied refrigerant in each collecting chamber. Furthermore, since the communication opening is formed in the header-partitioning wall at the same height as a height of a tube-connecting position of the header, a mixture of refrigerant in ■ each collecting chamber can be attained sufficiently.

It is preferable that a pair of guide rails disposed apart from each other are protruded from an external surface of a tube-non-connecting-side wall of the header and that a bracket is connected to the header by engaging a part of the bracket with the pair of guide rails. ^• An engagement of a part of the bracket with the pair of guide rails enables an easy attachment of the bracket and improves the accuracy of attaching position of the bracket.

In cases where a fitted portion of the bracket fitted on the header is integrally brazed to the header, the bracket is fixed to the header assuredly.

It is preferable that a plurality of brazing-material-holding grooves extending in a longitudinal direction of the header are formed on an_. external surface of a tube-connecting-side wall of the header. In cases where brazing materials such as powder brazing materials are applied to a connecting portion and therearound at the time of integrally brazing the header and the tube, the aforementioned brazing-material-holding grooves can effectively prevent the dropping of the brazing materials, resulting in stable brazing, which in turn can secure sufficient connecting strength. Furthermore, it is preferable that the tube is formed into a flat shape and that an inner fin having a plurality of communication apertures formed in a scattered manner is inserted into an inner space of the tube. It is also preferable that the tube is formed into a flat shape and that an inner space of the tube is divided by one or a plurality of tube-partitioning walls extending in a longitudinal direction of the tube and that each of the tube-partitioning walls is provided with one or a plurality of communication apertures. According to the aforementioned tubes, since the liquefied refrigerant passing through the tube can be mixed in each partitioned refrigerant passage via the communication apertures formed in the inner fin or the tube-partitioning wall, the discharging of the refrigerant from each partitioned refrigerant passage into the header can be further equalized. It is preferable that the header includes a sacrificial zinc layer for corrosion protection formed at an external surface thereof and that the zinc is diffused into the header by heat at the time of integrally brazing the header and the tube. This enhances corrosion protection of the header. It is preferable that the zinc concentration after the diffusion in a surface of the hollow header falls within a range of from 1 to 10 wt%. This further enhances the corrosion protection of the header.

It is preferable that a tube insertion aperture is formed in a tube-connecting-side wall and front and rear side walls extending from the tube-connecting-side wall and that a width of the tube is the same as or generally the same as a depth' of the header in a widthwise direction of the tube. In this case, since the tube insertion aperture is formed in a tube-connecting-side wall and front and rear side walls extending from the tube-connecting-side wall, machining for forming the tube insertion aperture can be simplified, resulting i 'remarkably improved processing efficiency thereof. Furthermore, since it becomes possible to insert the tube from the front or rear side wall of the header, the assembly can be improved. Furthermore, since the width of the tube is the same as or generally the same as the depth of the header in the widthwise direction of the tube, the header does not protrude from the widthwise sides of the tube . Thus, the heat exchanger can be further miniaturized. In order to prevent the displacement of the tube in the fore and aft direction and/or the dropping of the tube, it is preferable that each of the front and rear side walls of the header is provided with a tube-displacement-restricting piece bent toward the tube insertion aperture and fitted on a widthwise side surface of the tube. Brief Description of Drawings

Fig. 1A is a front view of a heat exchanger according to a first embodiment of the present invention, and Fig. IB is a top view thereof.

Fig. 2 is an enlarged cross-sectional view taken along the lines 2-2 in Fig. 1A.

Fig. 3 is an enlarged cross-sectional view taken along the lines 3-3 in Fig. 1A. Fig. 4 is a cross-sectional view taken along the lines 4- 4 in Fig. 2.

Fig. 5 is a perspective view showing the tube. Fig. 6 is a cross-sectional view showing a modification of a header structure. Fig.7 is a cross-sectional view showing another modification of a header structure.

Fig. 8A is a cross-sectional view showing still another modification of a header structure, and Fig.8B is a cross-sectional view showing still yet another modification of a header structure. Fig. 9A is a perspective view showing a modification of a tube inner structure, and Fig. 9B is a perspective view showing an inner fin inserted in the tube.

Fig. 10A is a front view of a heat exchanger according to another embodiment of the present invention, and Fig. 10B is a top view thereof. Fig. 11A is an enlarged perspective view showing the cross-section taken along the line 11-11 in Fig. 10A, and Fig. 11B is a perspective view showing the header before bending the tube-displacement-restricting pieces of the header. ^• Fig. 12 is a front view showing the left header constituting the heat exchanger shown in Figs. 10A and 10B.

Fig. 13A is a front view of a conventional heat exchanger, and Fig. 13B is a top view thereof.

Best Mode for Carrying Out the Invention

A Ireat exchanger 1 according to an embodiment of the present invention will be described in detail with reference to the attached drawings .

The heat exchanger shown in Figs. 1A and IB is a condenser made of aluminum for car air-conditioners or room air-conditioners . The reference numerals 1, 2 and 3 denote a heat exchanging flat tube, a hollow header and a fin (outer fin) , respectively. The fin 3 is a corrugated fin made of an aluminum brazing sheet.

A plurality of flat tubes 1 are disposed in parallel with each other at predetermined intervals with their opposite ends thereof communicated with a pair of hollow headers 2 and 2. Between the adjacent tubes 1, a fin 3 is disposed. The tubes 1 and the headers 2 are brazed. The brazing is performed generally by a method using a tube 1 on which brazing materials are previously clad is used, a method using a header 2 on which brazing materials are previously clad, or a method using both of the aforementioned tube 1 and header 2.

The inside space of each hollow header 2 is divided by a partition- 4 at a predetermined longitudinal position. The left header 2 has an inlet pipe 5 at its upper portion, and the right header 2 has an outlet pipe 6 at its lower portion. Whereby the refrigerant introduced into the left header 2- via the inlet pipe 5 passes through the plurality of tubes 1 in a meandering manner and flows out of the outlet pipe 6. The aforementioned hollow header 2 is comprised of a header pipe 2a having an approximately rectangular cross-sectional shape and header caps 2b having- an approximately rectangular cross- sectional shape for sealing the ends of the header pipe 2a. As shown in Figs. 2 and 3, the inner space of the header 2 is divided by header-partitioning walls 12 and 12 into three collecting chambers 13. Since the header 2 is formed into an angular cross-sectional shape such as a generally rectangular cross-sectional shape, although it is required to design such that the depth T of the header 2 is the same as or more than the width W of the tube 1, the width S of the header 2 can be arbitrarily designed regardless of the width W of the tube 1 or the depth T of the header 2. Thus, the width S of the header 2 can be designed smaller than the depth T of the header 2 as shown in Fig. 3. Accordingly, the inner volume of the header 2 can be reduced which in turn can fully miniaturize the whole heat exchanger and decrease the amount of refrigerant. Furthermore, since the header-partitioning walls 12 are provided in the header 2, the pressure resistance of the header 2 can also be fully secured.

The inner surface 14 of the tube-non-connecting-side wall of the collecting chamber 13 is formed into a curved surface as shown in Figs. 2 and 3. Since the inner surface 14 of the tube-non- connecting-side wall of the header 2 is formed into the curved surface, it is effectively prevented the refrigerant flowed out of the end portion of the tube 1 from returning to the end portion of the tube 1 even if the refrigerant collided against the inner surface of "the tube-non-connecting-side wall of the header 2 and rebounded therefrom. Thus, the refrigerant ' rebounded from the inner surface 14 will be gathered in the central portion of each collecting chamber 13 without interfering with the refrigerant flowed out of the end portion of tube 1 and then will flow downward in the header 2.

Each header-partitioning wall 12 is provided with communication openings 15 at the corresponding height as the height of each tube-connecting position of the header 2. Since the communication opening 15 allows the liquefied refrigerant in each collecting chamber 13 to be mixed with each other. Thus, it is prevented that larger amount of liquefied refrigerant is accumulated in the windward-side collecting chamber 13, resulting in even accumulation of liquefied refrigerant in each collecting chamber 13. The external surface 16 of the tube-non-connecting-side wall of the header 2 is formed into a flat shape. On the external surface

16 of this tube-non-connecting-side wall, a pair of guide rails

17 disposed at a predetermined distance' and extending in a longitudinal direction of the header 2 are provided as shown in

Fig. 2. Each guide rail 17 has an inwardly bent tip end forming a receiving dented portion 17a. On the other hand, a bracket 18 includes a flat-shaped fitting portion 18a and a mounting portion 18b outwardly protruded from the central portion of the fitting portion 18a. Thus, the bracket 18 has a generally T-cross- sectional shape. The opposite ends of the fitting portion 18a are inserted into and engaged with the aforementioned receiving dented portions 17a, whereby the bracket 18 is fixed to the header 2. In order to fix the bracket 18 to the header 2 assuredly, it is preferable that the fitting portion 18a and the header 2 .are integrally brazed each other.

As shown in Fig.5, the flat tube 1 is the so-called harmonica tube made of an aluminum extruded member having a flat cross- sectional shape. The inner space of the tube 1 is divided by tube-partitioning walls 10 extending in a longitudinal direction of the tube 1. In place of the aforementioned extruded tube, an electric resistance welded pipe may be used.

As shown in Figs. 2 and 4, a plurality of communication apertures 20 are formed in each tube partitioning wall 10 at predetermined intervals. The liquefied refrigerant passing through the tube 1 will be mixed between adjacent divided passages 19 through these communication apertures 20. Accordingly, the amount of liquefied refrigerant flowed out of each divided passage 19 into the header 2 will be equalized. The same effects can also be obtained by, for example, the tube structure shown in Figs. 9A and 9B. In this tube 1, an inner fin -27 having a plurality of communication apertures 26 formed in a scattered manner is inserted in the flat tube 1, whereby the inner space of the tube 1 is divided into a plurality of divided passages 19. Fig.10 shows a heat exchanger according to another embodiment. This ^•embodiment has the same structure as the aforementioned embodiment except for the header structure and the connecting structure of the header and the tube. Accordingly, the following explanation will be focused on the different structures. As shown in Fig. 11 and Fig. 12, the tube insertion aperture 30 to be formed in the header 2 is formed in a tube-connecting-side wall 31 and a front side wall 32 and a rear side wall 33 extending from the tube-connecting-side wall 31. By adopting this tube insertion aperture 30 which is opened toward three sides, machining for forming the tube insertion aperture 30 can be simplified, resulting in remarkably improved processing efficiency thereof. Furthermore, since it becomes possible to insert the tube 1 from the front side wall 32 or the rear side wall 33 of the header 2, the assembly can be improved. Furthermore, by adopting this structure, the width W of the tube 1 can be the same or generally the same as the depth T of the header 2. In this embodiment, since the width W of the tube 1 is the same as the depth T of the header 2, the header 2 does not protrude from the widthwise sides of the tube 1. Accordingly, the heat exchanger can be further miniaturized.

Furthermore, as shown in Fig. 11 B, a tube-displacement- restricting pieces 40 are formed on each of the front and rear side walls 32 and 33 of the header 2. As shown in Fig. 11A, the tube-displacement-restricting pieces 40 are bent toward the tube insertion aperture side of the front side wall 32 and that of the rear side wall 33 and fitted on the widthwise sides of the tube 1. Thus, the displacement of the tube 1 in the direction of the front and rear sides of the tube as well as the dropping of the tube 1 can be prevented assuredly. Generally, the aforementioned tube-displacement- restricting pieces 40 can be integrally formed together with the header body by an extrusion. Furthermore, the tube- displacement-restricting piece 40 is preferably formed to have an inwardly curved shaped as shown in Fig. 11B in order to attain perfect fitting onto the tube in consideration of the springback at the time of bending. Furthermore, when the tube- displacement-restricting piece 40 and the header 2 are integrally brazed, stronger junction thereof can be secured.

In the present invention, it is preferable that the maximum distance L from the end of the tube 1 communicated with the collecting chamber 13 to the curved inner surface 14 of the tube-non-connecting-side wall is 2 mm or more and 80% or less of the width W of the tube 1 (see Fig. 2) . When the distance L is less than 2 mm, the pressure loss at the refrigerant side increases, resulting in decreased fall-down velocity of the liquefied refrigerant, which in turn decreases the heat radiation performance . On the other hand, when the distance L exceeds 80% of the tube width W, the inner volume of the header 2 becomes the same as or larger than that of the conventional round header, which is not preferable. Furthermore, it is preferable that the header 2 includes a sacrificial zinc layer for corrosion protection formed at an external surface thereof and that the zinc is diffused into the header 2 by heat at the time of integrally brazing the header 2 and the tubes 1. This improves the corrosion resistance of the header 2, which in turn enables to provide a heat exchanger excellent in durability. As a conventional sacrifice anticorrosion method for a tube, it is known to spray zinc or form a zinc layer on an external surface of the tube. By adapting one of these known methods, the sacrificial zinc layer for corrosion protection can be formed on the external surface of the header 2. Concretely, immediately after the extrusion of the header 2, molten zinc is sprayed onto the external surface of the header 2. Thereafter, the zinc is diffused into the header by the heat at the time of brazing after the fabrication of the tubes 1, fins 3 and headers 2. Simply spraying zinc onto the external surface of the header fails to provide sufficiently stabilized sacrifice anticorrosion layer. However, by diffusing the zinc, stabilized sacrifice anticorrosion can be obtained.

In order to further improve the corrosion resistance, it is more preferable that the zinc ^' concentration after the diffusion in the surface of the header 2 falls within the range of from 1 to 10 wt%.

In order to further enhance the quick flow-down of the liquefied refrigerant, it is preferable that the curved inner surface 14 is provided with a plurality of vertically extending refrigerant-guiding grooves 21. Of course, it is necessary that the inner surface 14 of the.tube-non-connecting-side wall is formed' into a curved surface as a whole. Although the shape of the refrigerant-guiding groove 21 is not limited to a specific one, a V-shape may be exemplified.

Furthermore, as shown in Fig. 7, it is preferable that a plurality of brazing-material-holding grooves 24 extending in^" a longitudinal direction of the header 2 are formed on an external surface of the tube-connecting-side wall 23 of the header 2. ■ In cases where brazing materials are applied to the joining portion or therearound at the time of integrally brazing the tube 1 and the header 2, the brazing-material-holding grooves 24 can effectively prevent the brazing materials from being dropped during the brazing, resulting in stable brazing, which in turn secures sufficient joining strength. As the aforementioned brazing materials, powdered brazing materials, a mixture of powdered brazing materials and flux, and a mixture of the aforementioned mixture and combining materials can be exemplified. Although the shape of the groove 24 is not limited to a specific one, a V-shape may be exemplified.

In -the present invention, the header 2 is required to have an angular cross-sectional shape including a rectangular cross-sectional shape and a square cross-sectional shape. In this specification, it should be understood that the language "angular cross-sectional shape" is used to cover such a cross-sectional shape as shown in Figs. 8A and 8B.

As mentioned above, in the heat exchanger according to the present invention, since the header has not a conventional round cross-sectional shape but an angular cross-sectional shape including a rectangular cross-sectional shape and a square cross-sectional shape, it becomes possible to design such that the width of the header is smaller than the depth of the header, resulting in decreased inner volume of the header. As a result, the entire heat exchanger can be effectively miniaturized and the amount of refrigerant to be used can be decreased, which in turn can contribute to earth environment protection. Furthermore, since the header is provided with one or a plurality of header-partitioning walls extending in a longitudinal direction of the header, sufficient pressure resistance of the header can be obtained. Furthermore, since a tube-non-connecting-side wall of each of the collecting chambers has a curved inner surface, it is effectively prevented the refrigerant flowed out of the end portion of the tube from returning to the end portion.of the tube even if the refrigerant collides against an inner surface of the 5 tube-non-connecting-side wall of the header and rebounds therefrom. ' ' Thus, the refrigerant rebounded from the inner surface will be gathered in the central portion of each collecting chamber without interfering with the refrigerant flowed but of the end portion of tube and then flows downward in the header. 0 In the collecting chamber, in cases where the maximum distance from an end of the tube communicated with the collecting chamber to the curved inner surface of the tube-non-connecting-side wall is 2 mm or more and 80% or less of a width of the tube, the fall-down velocity of the liquefied refrigerant in the header, can be increased,' 5 and the inner volume of the header can be. effectively reduced. In cases where the curved inner surface is provided with a plurality of vertically extending refrigerant-guiding grooves, prompt fall-down and discharge of the liquid refrigerant in the header can be enhanced. 0 In cases where a communication opening is formed in the header-partitioning wall at the same height as a height of a tube-connecting position of the header, the liquefied refrigerant in each collecting chamber can be mixed with each other.

In cases where a pair of guide rails disposed apart from each 5 other are protruded from an external surface of a tube-non- connecting-side wall of the header and a bracket is connected to the header by engaging a part of the bracket with the pair of guide rails, the bracket can be easily attached to the header and the accuracy of attaching position of the bracket can be improved. In cases where a fitted portion of the bracket fitted on the header is integrally brazed to the header, the bracket can be fixed to the header assuredly.

In cases where a plurality of brazing-material-holding grooves extending in a longitudinal direction of the header are formed on an external surface of a tube-connecting-side wall of the header, the dropping of the brazing material can be effectively prevented, resulting in sufficient joining strength.

In cases where the tube is formed into a flat shape and that an inner fin having a plurality of communication apertures formed in a scattered manner is inserted into an inner space of the tube, or in cases where the tube is formed into a flat shape and that an inner space of the tube is divided by one or a plurality of tube partitioning walls extending in a longitudinal direction of the tube and that each of the tube-partitioning walls is provided with one or a plurality of communication apertures, since the liquefied refrigerant passing through the tube can be mixed in each partitioned refrigerant passage via the communication apertures formed in the inner fin or the tube-partitioning wall, the discharging of the refrigerant from each partitioned refrigerant passage into the header can be further equalized. In cases where the header includes a sacrificial zinc layer for corrosion protection formed at an external surface thereof and the zinc is.diffused into the header by heat at the time of integrally brazing the header and the tubes, corrosion protection of the header can be enhanced.

Furthermore, in cases where zinc concentration after the diffusion in a surface of the hollow header falls within a range of from 1 to 10 wt%, the corrosion protection of the header can be further enhanced. In cases where a tube insertion aperture is ^• formed in a tube-connecting-side wall and front and rear side walls extending from the tube-connecting-side wall and that a width of the tube is the same as or generally the same as a depth of the header, machining for forming the tube insertion aperture can be simplified, resulting in remarkably improved processing efficiency thereof. Furthermore, the assembly can be improved, and the heat exchanger can be further miniaturized.

In cases where each of the front and rear side walls of the header is provided with a tube-displacement-restricting piece bent toward the tube insertion aperture and fits on a lateral side surface of the tube, the displacement of the tube in the fore and aft direction and/or the dropping of the tube can be prevented.

This application claims priority to Japanese Patent Application No. 2000-325119 filed on October 25, 2000, the disclosure of which is incorporated by reference in its entirety. The terms and descriptions in this specification are used only for explanatory purposes and the present invention is not limited to these terms and descriptions. It should be appreciated that there are many modifications and substitutions without departing from the spirit and the scope of the present invention which is defined by the appended claims. A present invention permits any design-change, unless it deviates from- the -soul, if it is within the limits by which the claim was performed.

Industrial Applicability

The heat exchanger is preferably used as a condenser and/or an evaporator, and more preferably used as a condenser and/or an evaporator for use in car air-conditioning systems or room air-conditioning systems.

Claims

1. A heat exchanger, comprising: a hollow. header; and a plurality of heat exchanging tubes which are in fluid communication with said hollow header, wherein said header has an angular cross-sectional ^■ shape including a rectangular cross-sectional shape and a square cross-sectional shape, wherein said header is provided with one or a plurality of header-partitioning walls extending in a longitudinal direction of said header, whereby an inner space of said header is divided into a plurality of collecting chambers, and wherein a tube-non-connecting-side wall of each of said collecting chambers has a curved inner surface.

2. The heat exchanger as recited in claim 1, wherein a maximum distance from an end of said tube communicated with said collecting chamber to said curved inner surface of said tube-non- connecting-side wall is 2 mm or more and 80% or less of a width of said tube.

3. The heat exchanger as recited in claim 1, wherein said curved inner surface is provided with a plurality of vertically extending refrigerant-guiding grooves.

4. The heat exchanger as recited in claim 1, wherein a communication opening is formed in said header-partitioning wall at the same height as a height of a tube-connecting position of said header.

5. The heat exchanger as recited in claim 1, wherein a pair of guide rails disposed apart from each other are protruded from an external surface of a tube-non-connecting-side wall of said header, and wherein a bracket is connected to said header by engaging a part of said bracket with said pair of guide rails.

6. The heat exchanger as recited in claim 5, wherein a fitted portion of said bracket fitted on said header is integrally brazed to said header.

7. The heat exchanger as recited in claim 1, wherein a plurality of brazing-material-holding grooves extending in a longitudinal direction of said header are formed on an external surface of a tube-connecting-side wall of said header.

8. The heat exchanger as recited in claim 1, wherein said tube is formed into a flat shape, and wherein an inner fin having a plurality of communication apertures formed in a scattered manner is inserted into an inner space thereof.

9. The heat exchanger as recited in claim 1, wherein said tube is formed into a flat shape, and wherein an inner space of said tube is divided by one or a plurality of tube-partitioning walls extending in a longitudinal direction of said tube, and wherein each of said tube-partitioning walls is provided with one or a plurality of communication apertures.

10. The heat exchanger as recited in claim 1, wherein said header includes a sacrificial zinc layer for corrosion protection formed at an external" surface thereof, whereby zinc is diffused into said header by heat at the time of integrally brazing said header and said tubes.^'

11. The heat exchanger as recited in claim 10, wherein zinc concentration after the diffusion in a surface of said hollow header falls within a range of from 1 to 10 wt%.

12. The heat exchanger as recited in claim 1, wherein a tube insertion aperture is formed in a tube-connecting-side wall and front and rear side walls extending from said tube-connecting- side wall, and wherein a width of said tube is the same as or generally the same as a depth of said header in a widthwise direction of said tube .

13. The heat exchanger as recited in claim 12, wherein each of said front and rear side walls of said header is provided with a tube-displacement-restricting piece bent toward said tube, insertion aperture and fitted on a widthwise side surface of said tube.

.14. The heat exchanger as recited in claim 13, wherein said tube-displacement-restricting piece is integrally brazed to said header.