JPH01256797A - Heat exchanger - Google Patents

Abstract

PURPOSE:To provide a heat exchanger which is not susceptible to stress corrosion cracking and excels in corrosion resistance by forming a header plate with a core material layer made of copper zinc alloy covered with a zinc diffusion layer. CONSTITUTION:The present heat exchanger consists of the core section 1, a header plate 2 disposed at the end of the core section 1 and a plastic tank 3 held down by the header plate 2. The header plate consists of a core material layer 21 made of copper-zinc alloy and a zinc diffusion layer 4 covering the core material layer 21. For the copper-zinc alloy, brass containing 20-40weight% of zinc and remainder of copper is popularly used. The zinc diffusion layer 4 is formed by zinc plating, and the zinc plating should preferably have a thickness of 5-200mum on the surface of the core material layer 21. If it is less than 5mum, the corrosion resistance is not assured, and, if it is more than 200mum, there will be diminishing return in corrosion resistance. After inserting the rim of 31 of the opening of the plastic tank 3 into the U-channel 22 with an O-ring set in the bottom of it, the header plate 2 holds the tank down.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat exchanger that has excellent corrosion resistance and is free from stress corrosion cracking.

[Prior art]

Conventionally, engine cooling radiators and room heating heaters are known as heat exchangers, and these have basically the same structure or mechanism. Therefore, in the present invention, the radiator will be mainly explained for the sake of convenience.

The radiator is as shown in FIGS. 2 to 4.

The main body is a core portion 1 consisting of a brass tube 11 serving as a medium passage and copper fins 12 soldered to the tube.

A resin tank 3 is fixed to the core part 1 via a header plate 2 disposed at an end thereof.

As shown in FIG. 2, the opening edge 31 of the resin tank 3 is mounted in the O-shaped groove 22 of the header plate 2 via an O-ring 5. Also,
The header plate 2 is.

A brass material containing 30 to 35% by weight of Zn with the remainder substantially made of copper is used because it has excellent strength and good workability in -a and is relatively inexpensive.

On the other hand, as shown in FIGS. 3 and 4, the resin tank 3 is generally mounted using a caulking material 6 made of iron or stainless steel. However, this caulking material 6
With that working.

It is expensive because it requires materials, etc. Also, this caulking material 6 is used to attach the resin tank 3.

A large amount of stress is generated during the processing. Therefore, the header plate 2 is susceptible to stress corrosion cracking. Therefore,
Several attempts have been made to prevent this stress corrosion cracking.

For example, in Japanese Utility Model Application Publication No. 61-34386.

A heat exchanger is disclosed in which the surface of the header plate (metal seat plate) is coated with a corrosion-resistant layer. As this corrosion-resistant layer, a Cu plating layer, a Ni plating layer, a solder plating layer, a silicone rubber adhesive layer, etc. are used to prevent corrosion cracking of the outer peripheral wall of the recessed portion of the header plate.

[Problem to be solved]

However, in the heat exchanger disclosed in the above publication, the inside of the recessed portion of the metal seat plate is coated with a corrosion-resistant layer such as a Cu plating layer, but the corrosion resistance is not sufficient.

The present invention has been made in view of the problems of the prior art, and provides an outer circumferential wall of a concave portion of a ladder plate.

The present invention aims to provide a heat exchanger that is free from stress corrosion cracking at any part of the cooling water side immediately below the O-ring and has excellent corrosion resistance.

[Means for Solving the Problems] The present invention provides a heat exchanger comprising a core part, a header plate disposed at the end of the core part, and a resin tank fixed by the header plate, wherein the header plate is made of 1w4-zinc. A heat exchanger characterized by comprising a core material layer made of a (Cu-Zn) alloy and a zinc (Zn) diffusion layer formed on the surface of the core material layer.

In the present invention, the header plate has a core layer made of a copper-zinc alloy and a higher zinc concentration than the core layer formed on the surface of the core layer. It consists of a zinc diffusion layer. Moreover, the above-mentioned copper-zinc alloy is generally brass.

For example, it is possible to use an alloy containing 20 to 40% by weight of zinc, the balance being essentially copper.

Further, the zinc diffusion layer is formed on the surface of the core material layer made of the copper-zinc alloy by, for example, galvanizing or zinc spraying. Note that during this formation, heat treatment is performed after forming the zinc coating layer. This forms a zinc diffusion transition layer.

The above-mentioned zinc diffusion layer is preferably formed on the surface of the core material with a thickness of 5 to 200 μm. If the thickness is less than 5 μm, corrosion resistance is insufficient.
Even if the thickness exceeds 200 μm, there is little corresponding corrosion resistance effect. In addition, the zinc concentration in this zinc diffusion layer is higher than that in the core material.
n concentration.

It is preferable to set it as 40-60 heavy background%. If it is less than 40%, the corrosion resistance will not be sufficient, and if it exceeds 60%, there will be little commensurate effect.

In addition, the above copper-zinc alloy contains elements of Group 5 B such as P, As, Sb, and Bi or Group 4 B elements such as Si and Sn at 0.000%
It is preferable to contain 5 to 0.03 weight percent. As a result, the above alloy has the effect of suppressing dezincing.

Further, the core portion consists of a brass tube that serves as a medium passage and copper fins soldered to the brass tube.

Furthermore, the resin tank is made of a molded body of engineering plastic or the like.

[Action and effect]

In the heat exchanger according to the present invention, the header plate disposed at the end of the core portion includes a core layer made of a steel-zinc alloy and a zinc diffusion layer formed on the surface of the core layer. Therefore, a zinc diffusion layer with a less noble electrode potential is formed on the surface of the copper-zinc alloy.

Therefore, according to the present invention, stress corrosion cracking can be prevented from occurring based on the principle of cathodic protection.

A heat exchanger having a header plate with excellent corrosion resistance can be provided. In addition, in the present invention, unlike the prior art, there is no need for an auxiliary caulking plate such as an iron or stainless steel plate, so it is possible to significantly reduce the number of assembly steps, one hour, and materials, thereby reducing costs.

〔Example〕

An embodiment according to this example will be explained using FIG. 1. The heat exchanger according to this example includes a core part 1, a header plate 2 disposed at an end of the core part 1, and a resin crack tank 3 fixed by the header plate 2. (Please refer to Figure 4 for the entire heat exchanger).

The header plate 2 consists of a core layer 21 made of di-copper-zinc alloy and a zinc diffusion layer 4 formed on the surface thereof.

The header plate 2 configured in this way is
As shown in FIG. 1, the opening edge 31 of the resin tank 3 is inserted and fixed into the O-shaped groove 22 at the end of the header plate. Furthermore, an O-ring 5 is interposed at the bottom of the O-shaped groove 22 in a state in which it is in contact with the tip of the end portion 31 . Thereby, the O-ring 5 has the role of a buffer material between the O-shaped groove 22 and the end portion 31.

Next, change the material of the header plate 2.

A heat exchanger was constructed and a corrosion resistance test was conducted. That is.

As shown in Samples 1 to 4 in Table 1, header plates using four types of core material layers 21 having different composition ratios of Cu and Zn were tested. In addition, the zinc diffusion layer 4 has a total of seven
It was formed by Zn Menki.

That is, 2. This Zn plating forms a Zn plating layer with a thickness of 5 to 100 μm on the surface of the core material layer 21, respectively. Then, this was heated at 500°C to form zinc-diffused N4. The 20 m degree of the zinc diffusion N4 and its depth are shown in the same table.

As a comparative example, a header plate 2 made of Cu-30Zn, that is, 30 parts by weight of Zn and the remainder substantially only of an alloy of copper, was used as comparative product 1. Comparison product 2 has 1 on the surface of comparison product 1.
A Zn plating layer with a thickness of μm was formed and heated at 300° C. to form a zinc diffusion layer with a thickness of 2 μm. Further, a corrosion-resistant Cu plating layer was formed on the surface of Comparative Product 1, and Comparative Product 3 was prepared as a product corresponding to the disclosure in the above publication.

The thickness of this Cu plating is 20 μm.

The core portion 1 was composed of a brass tube and a copper fin, and the resin tank 3 was composed of a polycarbonate resin molded product.

As shown in Table 1, the Znfi degree, that is, the Zn diffusion concentration in the zinc diffusion layer in the header plate 2 is high at 40 to 60% by weight. In other words, the content of zinc in the core material layer 21 is greater than any of 25 to 35% by weight.

It can be seen that a zinc diffusion layer transition layer is formed between the core material layer 21 and the zinc diffusion layer 4.

Next, the corrosion resistance test in this example is as follows.

That is, fill the radiator with Matson fluid.

It measures and compares the time required until liquid leaks. Note that the internal pressure of the heat exchanger was set to 1.0 kg/cJ.

However, in the above test, due to the accelerated evaluation of the header plate, the end of the tube inserted into the header plate was sealed with resin, and the tube was inserted into the resin tank.
The Matson solution was sealed only between the goo plate and the plate.

The results of the above corrosion resistance test are shown in Table 1.

As is known from the same table, sample N11l according to the present invention
-4, no liquid leaked even after 20 hours. On the other hand, comparative products 1 and 2 took 6 to 10 hours,
Comparative product 3 began to leak liquid after 9 to 12 hours.

As described above, according to this example, it is possible to provide a high-grade, high-performance heat exchanger that prevents the occurrence of stress corrosion cracking and has excellent corrosion resistance.

Furthermore, since there is no need to use caulking material, it is possible to reduce the weight and cost of the heat exchanger.

The member comprising the core layer and diffusion layer used in the present invention can be used not only for other types of heat exchanger members such as oil coolers, but also for electrical and electronic terminals.

It can also be widely applied to various members where stress corrosion cracking is a problem, such as connectors and parts for wiring devices.

[Brief explanation of the drawing]

FIG. 1 is a side view of the header plate portion of a heat exchanger according to an embodiment of the present invention; FIGS. 2 to 4 show a conventional example; FIG. 2 is a side view of the same portion as above; FIG. is a side view of the same part as the above of another conventional example. FIG. 4 is a perspective view of the heat exchanger. l...core part. 11...Tube. 12...fin. 2. Header plate. 21... Core material layer. 22...0-shaped groove. 3...Resin tank.ゝ 31...Opening edge. 4...Zinc diffusion layer. 5...0 ring. 6...Caulking material.

Claims (1)

[Claims] In a heat exchanger comprising a core part, a header plate disposed at the end of the core part, and a resin tank fixed by the header plate, the header plate is made of steel-zinc (Cu- 1. A heat exchanger comprising a core material layer made of a Zn) alloy and a zinc (Zn) diffusion layer formed on the surface of the core material layer.