Heat exchanger made of aluminum alloy and method of producing same

Inactive Publication Date: 2010-03-04
CALSONIC KANSEI CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0032]In the heat exchanger of the present invention having the tube brazed with fin, Zn-containing portion constitutes an anode portion, and Zn-free portion constituting the cathode portion is protected from corrosion by preferential corrosion of the anode portion. As the Zn-free portion (side surface of the tube) acting as the cathode portion has a large area, Zn-containing portion (brazing composition coated surface) is corroded severely by the sacrificial anode effect.
[0033]Therefore, by reducing the area of Zn-free portion as much as possible, it is possible to suppress the progress of corrosion, inhibit preferential corrosion of the fillet, and suppress separation of the fins.
[0034]In a heat exchanger, an outer surface of header pipes having a large surface area may act as a cathode and increases corrosion of the fillet. However, by constituting the header pipe of core layer, outer sacrificial corrosion protection material, and inner brazing material, and by having the sacrificial corrosion protection material contai

Problems solved by technology

Such a potential gradient increases corrosion of the tube and causes pitting to occur, causing leakage of a refrigerant, and reducing the strength of the tube.
However, where the Zn-containing flux is used in the brazing, a large amount of Zn flows with the brazing liquid filler and concentrates to fillets joining fins and the tubes.
Where preferential corrosion of the fillets occurs, fins are separated from the tube surfaces, reducing heat transfer efficiency.
In

Method used

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  • Heat exchanger made of aluminum alloy and method of producing same
  • Heat exchanger made of aluminum alloy and method of producing same
  • Heat exchanger made of aluminum alloy and method of producing same

Examples

Experimental program
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example 1

[0126]An aluminum alloy having a composition shown in Table 1 was cast from molten alloy for constituting tubes, and aluminum alloy having a composition shown in Table 2 was cast from a molten alloy for constituting fins. For constituting header pipes, an aluminum alloy for core material, an aluminum alloy for sacrificial corrosion protection material, and an aluminum alloy for brazing material, each having a composition as shown in Table 3 were cast from molten alloys.

[0127]The aluminum alloy for a tube was subjected to heat treatment for homogenization, and was subsequently subjected to hot extrusion so as to have a shapes as shown in transversal cross section in FIG. 4 and FIG. 6A. In the tube shown in FIG. 4, the wall thickness was 0.30 mm, the width was 18.0 mm, the total thickness was 1.5 mm, the height of flat face of the side surface was 0.6 mm, and the curvature radius of the corner portion was 0.45 mm. In the tube shown in FIG. 6A, the wall thickness was 0.30 mm, the width...

example 2

[0148]Heat exchangers 100 were produced in the same manner as in Example 1, while the tubes were made of aluminum alloy having a composition shown in Table 5. The depth of corrosion in the tube 3 and the residual ratio of fins 4 were examined in the same manner as in Example 1. The results are shown in Table 5. In this case, brazing composition of No. 4 shown in Table 4 was applied as a coating composition.

TABLE 5Fin-tubeCorrosionResidualMnSijoint ratiodepth of tuberatio of finsTube(mass %)(mass %)Al(%)(μm)(%)Remark240.130.35balance9511580250.210.35balance967578260.300.35balance947276270.390.35balance957072280.470.35balance957273Excessive Mn,ReducedExtrudability290.300.15balance9610278300.300.26balance967275310.300.44balance957570320.300.52balance957572Excessive silicon,ReducedExtrudability

[0149]As shown in Table 5, the corrosion resistance of the tube 3 and the residual ratio of fins 4 vary depending on the Mn content and the Si content of the tube 3. Therefore, preferable contents...

example 3

[0150]Heat exchangers 100 were produced in a same manner as in Example 1, while the fins were made of aluminum alloy having a composition shown in Table 6. The depth of corrosion in the tube 3 and the residual ratio of fins 4 were examined in the same manner as in Example 1. The results are shown in Table 6. In this case, a brazing composition of No. 4 shown in Table 4 was applied as the coating composition.

TABLE 6Fin-tubeCorrosionResidualjointdepth ofration ofZnSiFeMnZrVCrratiotubefinsFin(mass %)(mass %)(mass %)(mass %)(mass %)(mass %)(mass %)(%)(μm)(%)Remark331.10.950.51.20.130.050.059510592341.30.950.51.20.13—0.05967574351.50.950.51.20.130.05—947078361.70.950.51.2—0.050.05957176372.00.950.51.20.13——959260381.50.60.51.20.13——9611361391.50.80.51.20.130.050.05967575401.51.10.51.20.130.050.05957378411.51.250.51.20.13——959060421.50.950.251.20.13——9410760431.50.950.411.20.130.050.05957280441.50.950.691.20.130.050.05967581451.50.950.851.20.13——948560461.50.950.50.850.130.050.05951057247...

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Abstract

A heat exchanger comprising a tube, a fin, and a header pipe, wherein the tube contains, in mass %, 0.15 to 0.45% of Mn, 0.20 to 0.50% of Si, and the balance of Al and unavoidable impurities, and is coated with a coating of brazing composition containing 1.0 to 5.0 g/m2 of Si powder, 4.0 to 10.0 g/m2 of KZnF3, and 0.5 to 3.0 g/m2 of binder; the fin contains, in mass %, 1.20 to 1.80% of Zn, 0.70 to 1.20% of Si, 0.30 to 0.80% of Fe, 0.90 to 1.50% of Mn, one or two or more selected from 0.05 to 0.20% of Zr, 0.01 to 0.10% of V, and 0.01 to 0.10% of Cr, and the balance of Al and unavoidable impurities; and the header pipe comprises a core material, outer sacrificial corrosion protection material, and an inner brazing material.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a heat exchanger made of an aluminum alloy and a method of producing the same. Specifically, the present invention relates to a heat exchanger made of an aluminum alloy and a method of producing the same in which separation of fins from tubes can be suppressed.[0003]Priority is claimed on Japanese Patent Application No. 2008-225324, filed Sep. 2, 2008, the content of which is incorporated herein by reference.[0004]2. Description of Related Art[0005]Heat exchangers made of aluminum alloy comprises tubes, fins, and header pipes as main constituents. The heat exchangers are produced by brazing those constituents. Conventionally, brazing sheets clad with Al—Si alloy brazing material have been widely used in their production. Production cost of the heat exchanger has been reduced by using extruded tubes (hereafter referred to as tubes) having surfaces coated with a brazing composition compose...

Claims

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Application Information

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IPC IPC(8): F28F9/04F28F1/12
CPCB21D53/08B23K1/0012F28F9/06F28F21/084F28F2275/04F28D1/05366
Inventor SOGABE, MASAHIROFUNATSU, TAKUMISHINHAMA, MASAYOSHIHYOGO, YASUNORIKATSUMATA, MASAYAASANO, MASAMI
Owner CALSONIC KANSEI CORP
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