Heat exchanger

Abstract

First depressed portions are formed on transverse sides of an insert so that the magnitude of depression of the first depressed portions increases as the first depressed portions approach toward the associated transverse side of the insert, whereby, as the first depressed portions are located to constitute a lower side of a core when brazing (in an oven), a brazing material, which is fused and is then allowed to flow into the first depressed portions in a brazing process, can be accumulated for retention within the first depressed portions by the surface tension of the brazing material so accumulated therein. Consequently, as the dispersion of more of the brazing material to outer fins, which constitute the lower side of the core when brazing, can be prevented, the erosion of the outer fins, which would otherwise occur due to the dispersion of the brazing material, can be prevented.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat exchanger which can effectively be applied to an intercooler for cooling air (suction air) which is sucked into an internal combustion engine to support combustion.

[0003] 2. Description of the Related Art

[0004] Normally, an air-to-air intercooler is constituted by a plurality of tubes, through which suction air is allowed to flow, fins joined to external surfaces of the plurality of tubes for increasing heat transfer surface thereof, a first header tank for distributing and supplying suction air to each of the plurality of tubes and a second header tank for collecting the suction air from which heat has been dissipated.

[0005] Incidentally, not only in intercoolers but also other heat exchangers, reinforcement plates (inserts), for reinforcing a heat exchanging core portion (hereinafter, simply referred to as a core portion) comprising tubes and fins, are formed into a configuration having a substantially U-shaped cross section, which has squared corners at a bottom side thereof, and are then brazed to end portions of the core portion.

[0006] In this construction, the reinforcement plates are intended to increase the mechanical strength of the core portion whereas the fins are intended to increase the heat transfer area of the intercooler or heat exchanger, and therefore the thickness of the fins (for example, 0.1 to 0.2 mm) is very thin when compared with the thickness of the reinforcement plates (for example, 2 mm).

[0007] Owing to this, there is caused a problem (of erosion) that, of the constituent components of the core portion, which are located on a lower side of the core portion at the time of brazing (and hence where a fused brazing material is easily accumulated) the thin fins are fused by the brazing material.

SUMMARY OF THE INVENTION

[0008] The present invention was made in view of this situation, and an object thereof is to prevent the occurrence of erosion at a portion of the core portion which is located on a lower side of the core portion at the time of brazing (and hence where a fused brazing material is easily accumulated).

[0009] With a view to attaining the object, according to a first aspect of the invention, there is provided a heat exchanger comprising a plurality of tubes (111) through which fluid flows, fins (112) joined to external surfaces of the plurality of tubes (111) for promoting heat exchange between fluid flowing between the plurality of tubes (111) and fluid flowing through the interior of the plurality of tubes (111), and reinforcement plates (130) disposed at end portions of a core portion (110) constituted by the plurality of tubes (111) and the fins (112) in such a manner as to extend substantially in parallel to the plurality of tubes (111) so as to reinforce the core portion (110) which is brazed at least to the fins (112), wherein depressed portions (131) are formed at transverse end portions of the reinforcement plate (130) on a side thereof which is brought into contact with the fins (112) in such a manner as to be depressed in an opposite direction to the fins (112).

[0010] According to this construction, at the time of brazing (in an oven), as will be described later with reference to FIG. 4, the depressed portions (131) are formed in such a manner as to be positioned on a lower side of the core portion (110). Consequently, in a brazing process, part of a brazing material which is fused and is then allowed to flow into the depressed portion (131) is then accumulated and held within the depressed portion (131) by virtue of the surface tension of the brazing material, whereby the erosion of the fins (112), which would otherwise happen due to the dispersion of the fused brazing material, can be prevented.

[0011] According to a second aspect of the invention, the depressed portions (131) are formed on transverse sides of the reinforcement plate (130).

[0012] According to this construction, even if either of the transverse sides of the reinforcement plate (130) is positioned to be the lower side, the occurrence of erosion can be prevented. Thus, as there is no need to consider the method of inserting the heat exchanger into a brazing oven, it is possible to increase the productivity of heat exchangers.

[0013] According to a third aspect of the invention, the depressed portions (131) are formed in such a manner as to extend in a groove-like fashion in the longitudinal direction of the reinforcement plate (130).

[0014] According to this construction, not only can the erosion of the fins (112) be prevented, over substantially the whole area of the reinforcement plate (130), but also the moment of inertia of area of the reinforcement plate (130) can be increased to improve the rigidity in bending of the reinforcement plate (130) (the strength of the core portion (110)).

[0015] According to a fourth aspect of the invention, the depressed portions (131) are formed in such a manner that the magnitude of depression (d) of the depressed portions (131) increases as the depressed portions (131) approach the associated transverse sides of the reinforcement plate (130).

[0016] According to this construction, it is ensured that the brazing material flowing to the lower side at the time of brazing is allowed to accumulate (be retained) within the depressed portions (131), and therefore it is ensured that the erosion of the fins (112) can be prevented.

[0017] Incidentally, the reference numerals in parentheses, to denote the above means, are intended to show the relationship of the means to specific means which will be described later in an embodiment of the invention.

[0018] The present invention may be more fully understood from the description of a preferred embodiment of the invention, as set forth below, together with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the drawings:

[0020] FIG. 1 is a front view of an intercooler according to an embodiment of the present invention;

[0021] FIG. 2 is a sectional view taken along the line A-A in FIG. 1;

[0022] FIG. 3 is a sectional view of an insert according to the embodiment of the invention; and

[0023] FIG. 4 is an exemplary view showing a layout in an oven for the intercooler according to the embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] In an embodiment of the present invention, a heat exchanger, according to the present invention, is applied to an air-to-air intercooler and FIG. 1 is a front view (as viewed from a direction from which air flows) of an intercooler 100 according to the embodiment of the present invention.

[0025] In FIG. 1, reference numeral 111 denotes flat tubes made of aluminum through which suction air is allowed to flow, and reference numeral 112 denotes outer fins formed into a wavy shape which are joined to flat surfaces of the tubes 111 for promoting heat exchange between cooling air which passes around the tubes 111 and the suction air. A rectangular cooling core portion (hereinafter, referred to as simply a core) 110 for cooling suction air is constituted by the outer fins 112 and the tubes 111.

[0026] In addition, louvers are provided in the outer fins 112, as shown in FIG. 2, by cutting and raising portions of the outer fins 112 in a shutter-like fashion in order to prevent the development of a temperature boundary layer by disturbing the flow of air. On the other hand, inner fins 114 having a similar construction to that of the outer fins 112 are disposed within the tubes 111.

[0027] Incidentally, the tube 111 is similar to a tube (an electric welded tube) which is fabricated of a sheet material, which is clad with a brazing material (in this embodiment, such as specified under A4045 or A4343) on front and back sides thereof, by bending and electrically welding the sheet material, and the outer fin 112 and the inner fin 114 are brazed to the tube 111 with the brazing material so clad on the tube 111.

[0028] In addition, as shown in FIG. 1, header tanks 120 are provided at longitudinal ends of the tubes 111 in such a manner as to communicate with the tubes 111, and the header tank 120 located on the right-hand side in FIG. 1 is intended to distribute and supply suction air to the respective tubes 111 whereas the head tank 120 located on the left-hand side in the same figure is intended to collect and recover the suction air which flows out of the tubes 111.

[0029] Incidentally, the header tank 120 comprises a core plate 121 made of aluminum to which the tubes 111 are brazed and a tank main body 122 made of aluminum which is joined to the core plate 121 so as to form an interior space within the header tank 120. The tubes 111 and the core plate 121, and the core plate 121 and the tank main body 122 are brazed together, respectively, with brazing material clad on front and back sides of the core plate 112.

[0030] In addition, provided on end portions of the core 110 where the header tanks 120 are not provided are inserts (reinforcement plates) 130 made of aluminum which extend substantially in parallel with the tubes 111 so as to reinforce the core portion 110. The insert 130 is brazed to the outer fins 112 and the header tanks 120 (the core plates 121) on a core portion 110 side and at longitudinal end portions thereof.

[0031] Note that the brazing material is clad on the insert 130 at least on the side thereof which faces the outer fin 112 and, in this embodiment, the insert 130 and the outer fin 112 are brazed together with the brazing material clad on the insert 130, and the insert 130 and the core plate 121 are brazed together with a brazing material clad on the core plate 121.

[0032] Incidentally, as shown in FIG. 3, the first depressed portions 131 are press formed on the insert 130 on a side thereof which is brought into contact with the outer fin 112 at transverse end portions of the insert 130 in such a manner as to be depressed in an opposite direction to the outer fin 112, and the first depressed portions 131 are each formed into a triangular groove-like configuration which extends substantially along the full length of the insert 130 in such a manner that the magnitude of depression “d” of the first recessed portions 130 increases as the respective depressed portions approach the transverse end portions of the insert 130.

[0033] Note that when used herein the transverse direction is referred to a direction which is normal to the longitudinal direction of the insert 130, the direction being substantially in parallel with a direction in which air flows.

[0034] In addition, formed at a transversely central portion of the insert 130 is a second substantially U-shaped depressed portion 132 which extends in a groove-like fashion in the longitudinal direction of the insert 130.

[0035] Next, a method for making the intercooler 100 will briefly be described.

[0036] The tubes 111, fins 112 and inserts 130 are assembled horizontally in a laminated fashion on a working table such as a surface plate to fabricate the core 110 (a core fabricating process). Next, after the core plates 121 are assembled to the core 110 (including the inserts 130) (a tank assembling process), the core plates 121 and the core 110 are placed in an oven in such a manner that the transverse direction of the insert 130 coincides with the perpendicular direction so as to be heated to be brazed together while the assembled condition of the core plates 121 and the core 110 is being retained with a fixture such as a wire (a brazing process).

[0037] Then, after the completion of the brazing process, required inspections such as leakage (brazing failure) inspections and dimensional inspections are carried out to complete the production of the intercooler.

[0038] Next, the features (function and effectiveness) of the present invention will be described.

[0039] In this embodiment, as the first depressed portions 131 are provided at the transverse end portions of the inserts 130, the depressed portions 131 are located on a lower side of the core 110, as shown in FIG. 4, when the intercooler 100 is placed in the oven for brazing.

[0040] Consequently, in the brazing process, the brazing material which is fused and is then allowed to flow into the first depressed portions 131 is allowed to be accumulated within the first depressed portions 131 for retention therein by virtue of the surface tension of the brazing material so accumulated, whereby the dispersion of more of the brazing material to the outer fin 112 which is located on the lower side of the core 110 at the time of brazing can be prevented. Eventually, the occurrence of erosion of the outer fin 112 by virtue of the dispersion of the brazing material can be prevented.

[0041] In addition, since the first depressed portions 131 are formed into the configuration in which the magnitude of depression “d” of the respective first depressed portions 131 increases as the first depressed portions 131 approach their associated transverse end portions of the insert 130, it is ensured that the brazing material which tends to flow to the lower side of the inter cooler 100 at the time of brazing can be accumulated (or retained) within the first recessed portions 131.

[0042] In addition, as the brazing material located above the transversely central portions of the inserts is retained within the second depressed portions 132, it is ensured that the erosion of the fins 112 can be prevented even above the transversely central portions of the inserts 130.

[0043] Furthermore, as the first depressed portions 131 are provided at the transverse end portions of the insert 130, the occurrence of the erosion can be suppressed even if either of the transverse end portions of the insert 130 is located to constitute the lower side of the intercooler 100 when placed in the oven for brazing. Thus, as there is no need to consider the way in which the intercooler 100 is inserted into the oven, the productivity of the intercooler 100 can be improved.

[0044] Moreover, as the first depressed portions 131 extend in a groove-like fashion, not only can the erosion of the outer fins 112 be prevented along the full length of the inserts 130 but also the moment of inertia of area of the inserts 130 can be increased to thereby improve the rigidity in bending of the inserts 130 (the strength of the core 110).

[0045] Another embodiment will be described below. In the aforesaid embodiment, while the invention is applied to an intercooler, the invention is not limited to such an application but may be applied to other types of heat exchangers (such as a condenser and a radiator) in which there is a large difference (by a factor of ten or less) in thickness between the insert (reinforcement plate) 130 and the fins 112 which are brazed thereto.

[0046] While the invention has been described by reference to the specific embodiments chosen for the purpose of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.

Claims

1. A heat exchanger comprising a plurality of tubes (111) through which fluid flows, fins (112) joined to external surfaces of said plurality of tubes (111) for promoting heat exchange between fluid flowing between said plurality of tubes (111) and fluid flowing through the interior of said plurality of tubes (111), and reinforcement plates (130) disposed at end portions of a core portion (110) constituted by said plurality of tubes (111) and said fins (112) in such a manner as to extend substantially in parallel to said plurality of tubes (111) so as to reinforce said core portion (110) which is brazed at least at said fins (112), wherein depressed portions (131) are formed at transverse end portions of said reinforcement plate (130) on a side thereof which is brought into contact with said fin (112) in such a manner as to be depressed in an opposite direction to the fin (112).

2. A heat exchanger according to claim 1, wherein said depressed portions (131) are formed on transverse sides of said reinforcement plate (130).

3. A heat exchanger according to claim 1, wherein said depressed portions (131) are formed in such a manner as to extend in a groove-like fashion in the longitudinal direction of said reinforcement plate (130).

4. A heat exchanger according to claim 1, wherein said depressed portions (131) are formed in such a manner that the magnitude of depression (d) of said depressed portions (131) increases as said depressed portions (131) approach the associated transverse sides of said reinforcement plate (130).