JPS58187798A - Heat exchanger - Google Patents

Abstract

PURPOSE:To form a heat exchanger which has a core plate of excellent corrosion resistance and excellent sealability of a resin tank with the plate. CONSTITUTION:A low voltage layer 12 which is made of mere metal of electrode voltage of core plate material is integrally formed in a thickness of 20- 80mum on the overall surfaces of resin tanks 3, 6 of a core plate 5. Thus, low voltage phase 12 of the range to 20mum of the limit that the sacrificing effect of the low voltage layer is performed is formed, thereby improving the sealability with a sealing member 13 and the corrosion resistance of the other member.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger in which a resin tank and a core plate are caulked and fixed via a sealing member.
For example, it is effective when used as an automobile radiator.

An object of the present invention is to provide a heat exchanger that has excellent sealing properties between a resin tank and a core plate, and also has excellent corrosion resistance of the core plate.

The present invention will be explained below based on an embodiment shown in the drawings.

Figure 1 shows an automobile radiator. 1 is a water chamber made of aluminum alloy (A3003 or A3004), 2 is a corrugated fin, and the core material is made of aluminum alloy (A3003). It is clad with brazing filler metal (A4004). Reference numeral 5 denotes core plates disposed at both ends la of the water chamber 1, which are also made of aluminum alloy (A3003 or A6951). 11 is a reinforcing side plate made of aluminum alloy (A7NO1). Then, these members (water chain 1, fins 2°, core plate 5, side plate 11) are brazed into seven pieces in a furnace to form the radiator core portion A.

Reference numeral 3 denotes an upper tank, which is made of a molded product of nylon resin containing glass fiber as a reinforcing agent, for example, and is molded integrally with an input vib 10 for introducing cooling water from the engine. 6 is also a lower tank made of resin, and is integrally molded with an outlet vibe 7 and a drain pipe 8, which sends out the cooling water that has undergone heat exchange in the core part A to the engine. and,
The connection between the upper and lower tanks 3 and 6 and the core part A is
As shown in the figure, the end 5a of the core plate 5 and the tank 3
A sealing member 13 (for example, made of nitrile rubber) having a rectangular overall shape and a circular cross section is interposed between the shoulder portion 3a of the core plate 5 and the shoulder portion 3a of the core plate 5. With the core plate end 5a interposed between the shoulders 3
Fix it watertight by caulking it to a.

In addition, the entire inner surface of the core plate 5, in other words, the tank 3
(6) The part 5b directly facing the water and the shoulder part 3
As shown in FIG.
) is formed, and this 'low potential layer 1
Due to sacrificial corrosion in step 2, constant contact with cooling water causes corrosion to
Corrosion resistance on surfaces that are prone to corrosion is greatly improved.

Here, the present inventors originally devised to form a low potential layer 12 of 80 to 120μ on the entire inner surface of the core plate 5, but in this case, it would be in contact with the sealing member 13 of the end portion 5a for sealing. Sacrificial corrosion (laminar corrosion) occurs even in areas where corrosion should be maintained, impairing the sealing performance with the seal member 13, and there is a risk that water may leak from this area.

Therefore, the heat exchanger having the above structure requires a low potential layer 12 that satisfies both of the two conflicting properties of sealing performance and corrosion resistance. That is, as shown in Fig. 3, the upper limit of the low potential layer is set to 80μ so that the sealing performance is not impaired by sacrificial corrosion, and the lower limit is set to 80 μm so that the sealing performance is not impaired by sacrificial corrosion. A low potential phase 12 is formed in the range up to 20μ, which is the limit at which the effect can be exhibited, thereby improving the sealing performance with the sealing member 13 and the corrosion resistance of other parts.

Next, a method of forming this low potential layer 12 will be explained.

As a first embodiment, as shown in FIG. 1, a water tube 1. Inside the fins 2 and the core plate, 1 to 3% Zn is added to aluminum, and 0% Ca, an element that has the effect of preventing Zn evaporation, is added when vacuum treatment is applied, which will be described later.
．． 3% added low potential layer 12 (in this case, Li may be used although it has the same effect as Ca, and Sn is an element that has a high vapor pressure and makes the potential less base than the core plate 5).

5. A core plate cladding with a low potential layer containing In, Ga, etc.).5. The side plates 11 are assembled and integrally brazed by vacuum brazing to complete the radiator core A.

In addition, as a means of vacuum brazing, each part is held in the radiator core with an assembly jig, and in that state it is heated to a temperature of 6.
Place in a vacuum furnace at 1Q°C and vacuum degree of 5 x 10 atm.
Heat for a minute. At this time, the surface Zn concentration on the inner surface of the core plate 5 is 0.3 to 0.8%, and the diffusion depth is 40%.
~80μ.

Thereafter, the radiator core A thus created is attached to the resin tank by integrally caulking the ends 5a of the core plate 5 through the resin tank j/6 seal member 13 as described above. Complete the ji.

A corrosion test was conducted on the corrosion resistance of the inner surface of this radiator using only the corrosive water specified in JKSK2234 paragraphs 6 and 34 using a JISK2234 circulation test device. Even when inspected by pressure, no leakage occurs, and the pitting depth of the low potential layer 12 of the core plate 5 is 0.08 or less,
It was found that it has corrosion resistance that poses no practical problems. The test results are shown for the core plate 5 without any treatment, and for the low potential layer with the same alloy composition as described in Example 1.
Table 1 shows a comparison with the one with 0 μ cladding, and it was found that there was a clear difference.

Chapter 1 Table Next, a second example will be described.

First, a radiator core is manufactured by vacuum brazing according to the method described in the first embodiment, and then a flux containing zinc chloride (ZnC1a) as a main component (for example, Alcoa 33 Franks) is applied to the entire inner surface of the core plate 5 as a low potential member. ) with a brush or the like. after that,
Heating is performed in the air for 15 minutes at a temperature of 500°C and for 5 minutes at a temperature of 600°C to diffuse Zn in the flux into the core plate. After this, 10% nitric acid (HNOJ)
) and water to remove the flux and remove the radiator core A.
Dry. At this time, the surface Zn concentration of the surface of the core plate 5 to which the flux is applied is 0.5 to 2%, and the diffusion depth is 40 to 80 μ. Thereafter, the radiator core A is integrally caulked with the end portion 5a of the core plate 5 via the seal member 13 between the resin tanks 3 and 6, as in the first embodiment, to complete the radiator.

In the method of this second embodiment, the low potential layer 12 is not formed of a cladding alloy, but the sacrificial effect is exerted by the diffusion of Zn in zinc chloride, and the effect is that of the low potential grains described in the first embodiment. It has the same effect as the layer's crack throat. JISK223 for radiators manufactured by this method
6.3.4 of JISK2234 using the circulation test device of 4.
When a corrosion test was conducted using only the corrosive water specified in Section 1.
The corrosion resistance was as shown in Table 1, and it was found that the material had corrosion resistance that caused no practical problems.

A third embodiment will be explained.

In this third embodiment, the core A is assembled by mechanical coupling methods such as tube expansion and caulking without using soldering or brazing, and is caulked and fixed to resin tanks 3 and 6 via sealing material 13 to complete the radiator. This is applied to the core plate of a solderless aluminum radiator. The alloy composition of the core plate low potential layer is AN-Zn system, and its thickness is 20
The core plate 5 is clad with μ. In this case, since it is a non-vacuum brazing method, Z
The sacrificial anticorrosion effect of the low potential layer without n diffusion and evaporation is the same as in Example 1.2.

The corrosion resistance of the radiator manufactured by the method of this third example was tested according to JIS2234 circulation test equipment.
When a corrosion test was carried out using only the corrosive water described in Section 6.3.4 of 34, it was found that the corrosion resistance was as shown in Table 1, and there was no problem in practical use.

Further, in the above-mentioned embodiments, a radiator for an automobile was explained, but the heat exchanger of the present invention is not limited to an radiator for an automobile. Needless to say, it can be widely used as a device for exchanging heat between

As explained above, the heat exchanger of the present invention has a core plate 5
A low potential layer 12 of 20 to 80 μm made of a metal with an electrode potential lower than that of the material of the core plate 5 is formed on the entire inner surface of the resin tanks 3 and 6 and the core plate 5.
It has the excellent effect of being able to always maintain a good seal between the core plate 5 and the corrosion resistance of the core plate 5.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of the heat exchanger of the present invention, Fig. 2 is a cross-sectional perspective view showing the main parts of the heat exchanger shown in Fig. 1, and Fig. 3 is an explanation showing the effects of the heat exchanger of the present invention. It is a diagram. 1...Chape, 3.6...Tank, 5...Core plate, 12...Low potential layer. Representative Patent Attorney Takashi Okabe

Claims (1)

[Claims] In a heat exchanger comprising a resin tank, a core plate that is tightly caulked and fixed to the resin tank via a sealing member, and a chain that has an end connected to the core plate, the A heat exchanger characterized in that a 20 to 80 μm low potential layer made of a metal whose electrode potential is less noble than that of the core plate material is integrally formed on the entire side surface of a resin tank.