JP2004156561A - Fin tube with high thermal resistant/high corrosion resistant film for vehicle fuel cooler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fin tube for a vehicle fuel cooler, having high performance including high thermal resistance and high corrosion resistance, by using a combination of different surface treatment technologies (film forming means). <P>SOLUTION: In a fin tube with a high thermal resistant and high corrosion resistant film used for a vehicle fuel cooler, the high thermal resistant/high corrosion resistant film is composed of (1) a Ni or Co film deposited on the surface of the fin tube, (2) a Zn-Ni alloy film deposited on the Ni or Co film, and (3) an electrodeposition layer applied on the Zn-Ni alloy film. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
A fin tube is one of the heat exchangers used for cooling a fluid (liquid or gas) in automobiles and home electric appliances. In this method, fins are spirally wound around a fluid pipe (pipes made of iron, copper, aluminum, SUS, etc.) and fixed by welding or brazing.
[0002]
This kind of general fin tube is subjected to various surface treatments (such as plating and painting) for the purpose of preventing rust or improving the appearance.
[0003]
One major field of application for fin tubes is in automotive fuel coolers.
In this case, needless to say, the fin tube for the fuel cooler of the automobile is required to have high heat resistance and high corrosion resistance (rust prevention) in view of the usage environment.
[0004]
In particular, recently, high performance requirements have been imposed. For example, a fin tube for a fuel cooler of a high-performance vehicle without holes is required for a service period of 15 years and / or a mileage of 150,000 miles. ing. At present, such high-performance fin tubes cannot be obtained by conventional surface treatment techniques.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a fin tube for a fuel cooler of an automobile, which can meet the above-mentioned demand for high performance.
[0006]
The present inventors have made intensive studies to provide a fin tube for a fuel cooler of a high-performance vehicle by a new surface treatment technology.
As a result, in the present inventors, in the improvement and improvement measures of the fin tube only by the conventional plating technology, the fin tube has a unique complicated shape and structure, and forms a uniform plating film on the surface thereof. It has been found that it is difficult to accomplish this, and this prevents the realization of a high-performance fin tube.
[0007]
The present invention has been made in order to solve the disadvantages caused by the plating specifications alone based on the above findings. The greatest feature of the present invention is that a uniform film structure is realized on a fin tube having a complicated shape and structure by adopting a composite film forming means of plating specification and electrodeposition coating specification. On the point.
[0008]
[Means for Solving the Problems]
To summarize the present invention, the first invention of the present invention is a fin tube for a fuel cooler of an automobile having a high heat resistance and high corrosion resistance film, wherein the high heat resistance and high corrosion resistance film is
(1). Ni or Co plating layer provided on the surface of the fin tube,
(2). A Zn-Ni alloy plating layer provided on the Ni or Co plating layer,
(3). An electrodeposition coating layer provided on the Zn-Ni alloy plating layer,
The present invention relates to a fin tube for a fuel cooler of an automobile having a high heat-resistant and high corrosion-resistant film.
[0009]
Further, the second invention of the present invention is a fin tube for a fuel cooler of an automobile having a high heat resistance and high corrosion resistance film, wherein the high heat resistance and high corrosion resistance film is
(1). Ni or Co plating layer provided on the surface of the fin tube,
(2). A Zn-Ni alloy plating layer provided on the Ni or Co plating layer,
(3). A chromate film layer provided on the Zn-Ni alloy plating layer,
(4). An electrodeposition coating layer provided on the chromate film layer,
The present invention relates to a fin tube for a fuel cooler of an automobile having a high heat-resistant and high corrosion-resistant film.
[0010]
Hereinafter, the technical configuration and embodiments of the present invention will be described in detail.
Although the technical configuration of the present invention will be described with reference to the drawings, it is not to be understood that the present invention is not limited to the drawings.
[0011]
When using paint specifications as a means of improving the performance of the fin tubes for automobile fuel coolers by surface treatment, the coating on the tip (edge) of the fin, which is most susceptible to flying stones, becomes thinner than other parts. . This is due to the complicated shape and structure of the fin tube as described above and cannot be avoided.
If the thickness of the coating film is increased in order to solve the above-mentioned drawbacks, the most important characteristic of the fin tube, that is, the heat radiation performance is reduced.
[0012]
On the other hand, in plating specifications such as electroplating, the tip (edge) of the fin has a higher current efficiency, so that the tip (edge) of the fin becomes relatively thicker than other portions. However, plating is difficult to adhere to the welded portion or brazed portion (root portion of the fin) between the fin and the pipe, and as a result, if a corrosion factor such as moisture remains in the portion, corrosion of the portion proceeds. .
In the plating specifications, depending on the type of metal or alloy to be plated, for example, Zn plating or the like has low heat resistance, and from the viewpoint of the use environment of the fin tube for a fuel cooler of an automobile, the heat resistance is at least 100 ° C. or more. It is important to have a plating specification that exhibits sufficient corrosion resistance (rust prevention) under extremely high temperatures.
[0013]
The most significant feature of the technical configuration of the present invention is that
1). First, on the surface of the fin tube, form a specific plating film with high heat resistance and high corrosion resistance according to plating specifications,
2). The thinning of the plating film at the welding portion or brazing portion (root portion of the fin) of the fin and the pipe generated under the plating specification is performed by forming a coating film according to the electrodeposition coating specification. The brazing part is thickened,
The technical feature of the present invention is to adopt a technical configuration that realizes a uniform heat-resistant and high-corrosion-resistant coating structure on the entire surface of the fin tube.
[0014]
1 and 2 are views for explaining a fin tube (1) for a fuel cooler of an automobile according to the present invention.
FIG. 1 is a perspective view of the fin tube (1).
FIG. 2 is a view corresponding to an enlarged view of a cross section (upper half) of the center line of the fin tube (1) in FIG. 1, and is for explaining a film structure formed on the fin tube (1) according to the present invention. FIG. That is, it should be considered that the film structure shown in FIG. 2 is an enlarged and easy-to-understand schematic diagram of the actual film structure. It should be noted that FIG. 2 shows only a cross-sectional portion for clarity of illustration, and other portions are omitted.
[0015]
As shown in FIG. 1, the fin tube (1) of the present invention is manufactured by winding a fin (1b) on a pipe (1a), brazing or welding, and its appearance. The shape is the same as the conventional one.
[0016]
FIG. 2 is a diagram useful for understanding the technical configuration of the present invention.
In FIG.
A layer indicates a plating layer according to 1), that is, a Ni or Co plating layer provided on the surface of the fin tube and a Zn-Ni plating layer provided thereon,
The layer B indicates the electrodeposition coating layer according to the above 2) provided on the layer A.
A portion A ′ of layer A in FIG. 2 is a portion where the pipe (1a) and the fin (1b) are joined by brazing or the like, and is a portion where plating is difficult to be applied in a plating specification and a plating film becomes thin.
A portion B ′ of the layer B in FIG. 2 is a portion where the coating film becomes thicker on the thin film of the plating film of the portion A ′ in the electrodeposition coating specification.
In FIG. 2, reference material (1c) shows a fillet of copper brazing.
[0017]
As described above, the present invention uses a plating specification using a specific plating component having high heat resistance and high corrosion resistance in combination with an electrodeposition coating specification, and the latter (electrodeposition coating specification) uses the former (plating specification) piping ( 1a) and the fin (1b) are formed into a protective film for compensating for thinning of the fixing portion and preventing external damage (damage due to flying stones), and have a uniform high heat resistance and high corrosion resistance as a whole. It is possible to provide a fin tube for a fuel cooler of an automobile having a film structure of the above.
[0018]
Next, the plating specifications employed in the present invention will be described.
As described above, the present invention first forms a Ni or Co plating layer on the surface of the fin tube as a first step, and forms a Zn-Ni alloy plating layer on the Ni or Co plating layer as a second step.
[0019]
In order to improve the corrosion resistance of pipes (pipes), joints, clamps, and other members of automobiles and the like, those having a multi-layer coating of a Zn plating layer and a chromate coating (Japanese Patent Application Laid-Open No. 60-165387) have been proposed. I have. However, they are effective in improving the corrosion resistance when used at room temperature, but do not exhibit corrosion resistance in a high temperature environment.
[0020]
As a heat-resistant and corrosion-resistant multi-layer steel material that can withstand use in a high temperature environment such as in an engine room of an automobile, a multi-layer film of Ni or Co plating layer and Zn-Ni alloy plating layer, and a multi-layer film combining this with a chromate film Those having a layer coating are known (JP-A-2-120034, JP-A-3-47987, and JP-A-8-134885).
[0021]
The present invention is a multi-layer coating of the above-described Ni or Co plating layer and a Zn-Ni alloy plating layer, and furthermore, a plating specification of a multi-layer coating in which a chromate film is combined with a high heat-resistant and high corrosion-resistant multilayer plating steel material, Can be used.
The present invention utilizes these known plating specifications, but by combining the above-mentioned disadvantages caused by the non-uniform coating caused when applying these to a fin tube having a complicated shape and structure, by combining with other coating specifications. This is a solution which is not known in the prior art and is the greatest feature of the present invention.
[0022]
In the present invention, the Ni or Co plating layer as a lower layer of the first layer of the film configuration on the fin tube may be formed as desired.
In the present invention, the Ni plating layer is understood to mean a plating layer made of Ni alone or a Ni alloy (excluding a Zn-Ni alloy used in the next step) such as Ni, Ni-P, Ni-B. Should.
Further, in the present invention, the Co plating layer should be interpreted to mean a plating layer made of Co alone or a Co alloy such as Co or Co-Ni.
In the present invention, the thickness of the Ni or Co plating layer may be set as desired. For example, the thickness of the plating layer may be 0.2 to 10 μm from the viewpoints of the ability to cover the substrate and the heat and corrosion resistance.
[0023]
For the Ni plating layer, for example, a Watt bath is used for the Ni plating film, and the Ni-P plating film is a five-fold diluted solution of the trade name “Schuma-S-780” of Nippon Kanigen Co., Ltd. The plating film may be formed using a bath having a trade name “BEL-801” of Uemura Kogyo Co., Ltd.
For the Co plating layer, for example, a Co plating layer uses a bath of cobalt chloride 150 g / l, boric acid 50 g / l, and pH 5, and a Co—Ni alloy plating film has nickel sulfate 140 g / l, cobalt sulfate 110 g / l, and borane. It may be formed using a bath of 30 g / l of acid, 15 g / l of potassium chloride, and pH 4.5.
[0024]
In the present invention, the Zn—Ni alloy plating film formed as the upper layer of the Ni or Co plating layer as the lower layer of the first layer may be formed as desired.
For example, it may be formed by electroplating using a known chloride bath or sulfuric acid bath, and the Ni content is preferably in the range of 2 to 20% Ni from the viewpoint of corrosion resistance, or a chromate film is formed in the next step. In this case, it is preferable from the viewpoint of the formability of the chromate film.
[0025]
In the present invention, a chromate film may or may not be formed on the Zn-Ni alloy plating layer as an upper layer of the first layer.
In the case of forming a chromate film, a treatment solution obtained by adding sulfuric acid to chromic acid or dichromic acid or a commercially available chromate treatment solution for Zn-Ni plating, for example, "Z-80YMU" manufactured by Ebara Cordierite Co., Ltd. may be used.
[0026]
In the present invention, the formation of a specific plating film according to the plating specifications described above is followed by the formation of a coating film according to the coating specifications comprising electrodeposition coating.
[0027]
In the present invention, a coating specification consisting of electrodeposition coating is used in combination with the plating specification as described above.
As is well known, there are cationic and anionic types of electrodeposition coating, but the anion type has an electrolytic action, and the metal components on the tube surface are reversely electrolyzed and eluted into the electrodeposition coating solution, resulting in corrosion resistance. Because of the decrease, the cationic electrodeposition is more preferable.
[0028]
In the present invention, the electrodeposition coating layer may be formed as desired by cationic electrodeposition coating. In particular, from the viewpoint of corrosion resistance and the like, an epoxy resin-based cationic electrodeposition coating is preferable.
[0029]
In the present invention, the thickness of the coating film formed by electrodeposition may be set as desired. In general, when the film thickness is small, the corrosion resistance is low, and when the film thickness is large, the adhesion and the productivity are poor, so that a film thickness of 15 to 150 μm is preferable.
For example, in the case of using an epoxy resin-based product name “Electron W Coat” manufactured by Kansai Paint Co., Ltd. as a cationic electrodeposition paint as the electrodeposition coating, the electrodeposition is divided into a plurality of times so that the film thickness becomes 15 to 150 μm. An electrodeposition coating film may be formed by coating and baking at a baking temperature of 150 to 220 ° C.
[0030]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples.
It goes without saying that the present invention is not limited to the embodiment.
[0031]
(First embodiment)
A steel strip having a thickness of 0.5 mm and a width of 8 mm was spirally wound around a double-wound steel pipe having an outer diameter of φ8 mm and a wall thickness of 0.7 mm manufactured by a conventional method, and was brazed with copper to produce a fin tube.
(1) Using a plating bath of 150 g / l of cobalt chloride, 50 g / l of boric acid, pH 5 on the fin tube, a cobalt plating film (film thickness 1 μm at the root of the fin, 2 μm at the tip of the fin) as a lower layer. The film was formed at a temperature of 60 ° C. and a current density of 5 A / dm ² .
(2) A zinc-nickel alloy plating film (film thickness: 35 ° C., current density: 3 A / dm ² ) was formed on the cobalt plating film by using a plating bath of ZIN-ROY process of Ebara Ujilite Co., Ltd. 5 μm at the root of the fin and 10 μm at the tip of the fin).
(3) On the zinc-nickel alloy plating film, a chromate film was formed by immersing a ZN-80YMU chromate solution of Ebara Ujilite Co., Ltd. at a concentration of 50 ml / l at a liquid temperature of 50 ° C. for 20 seconds.
(4) On the chromate film, use a cationic electrodeposition paint having a trade name of “Electron W Coat” manufactured by Kansai Paint Co., Ltd. to have a film thickness of 25 to 35 μm at the fin tip and 90 to 120 μm at the fin root. Electrodeposition coating was performed twice so as to obtain a coating film, which was baked at a baking temperature of 180 to 200 ° C.
The fin tube manufactured as described above has high heat resistance and high corrosion resistance, and is therefore excellent for use as a fuel cooler for automobiles.
[0032]
(Second embodiment)
A steel strip having a thickness of 0.5 mm and a width of 8 mm was spirally wound around a single-wound steel pipe having an outer diameter of φ8 mm and a wall thickness of 0.7 mm manufactured by a conventional method, and was brazed with copper to produce a fin tube.
(1) A nickel plating film (thickness of 1 μm at the root of the fin, 2 μm at the tip of the fin) as a lower layer on the fin tube is used as a watt bath, at a bath temperature of 55 ° C. and a current density of 3 A / dm ^2. Formed.
(2) ZnCl ₂ on the nickel plating film 100 g / l, NiCl ₂ Using a zinc-nickel alloy plating bath of 6H ₂ O 130 g / l, NH ₄ Cl 200 g / l, pH 5.7, bath temperature 35 ° C., current density 3 A / dm ² Then, a zinc-nickel alloy plating film (film thickness 4 μm at the root of the fin and 8 μm at the tip of the fin) was formed by an acidic bath.
(3) 10 g / l of ZnO, 10 g / l of NiSO ₄ , 130 g / l of NaOH, 100 ml / ml of Ni-T solution (trade name of Japan Surface Treatment Chemical Co., Ltd.) on the zinc-nickel alloy plating film by the acidic bath. At a concentration of 1 and a liquid temperature of 25 ° C. and a current density of 4 A / dm ₂ , a zinc-nickel alloy plating film (film thickness of 5 μm at the root of the fin and 7 μm at the tip of the fin) was formed by an alkaline bath.
(4) On the zinc-nickel alloy plating film by the alkaline bath, use a cationic electrodeposition paint of trade name “Elecron W Coat” manufactured by Kansai Paint Co., Ltd. The electrodeposition coating was performed twice so as to be 90 to 120 μm at the root of the fin, and the coating was formed by baking at a baking temperature of 180 to 200 ° C.
The fin tube manufactured as described above has high heat resistance and high corrosion resistance, and is therefore excellent for use as a fuel cooler for automobiles.
[0033]
【The invention's effect】
Although surface treatment techniques such as plating have been employed to improve the performance of the fin tube, it has been difficult to form a uniform plating film due to the complicated shape of the fin tube.
The present invention can provide a fin tube for a fuel cooler of a high-performance automobile which requires particularly high heat resistance and high corrosion resistance by using different kinds of film forming means, that is, plating specification and electrodeposition coating specification together. I made it.
[Brief description of the drawings]
FIG. 1 is a perspective view of a fin tube (1) for a fuel cooler of an automobile according to the present invention.
FIG. 2 corresponds to an enlarged view of a cross section (upper half) of a center line of the fin tube (1) in FIG. 1, and is a view for explaining a film structure on the tube (1).
[Explanation of symbols]
1 fin tube 1a for fuel cooler of automobile Pipe 1b fin 1c Fin fillet A of copper brazing A plating layer A 'thin film of plating layer Site B ... Electrodeposition coating layer B '... Thick portion of electrodeposition coating layer

Claims (3)

In a fin tube for a fuel cooler of an automobile having a high heat resistant and high corrosion resistant film, the high heat and high corrosion resistant film is
(1). Ni or Co plating layer provided on the surface of the fin tube,
(2). A Zn-Ni alloy plating layer provided on the Ni or Co plating layer,
(3). An electrodeposition coating layer provided on the Zn-Ni alloy plating layer,
A fin tube for a fuel cooler of an automobile having a high heat-resistant and high corrosion-resistant film, comprising: In a fin tube for a fuel cooler of an automobile having a high heat resistant and high corrosion resistant film, the high heat and high corrosion resistant film is
(1). Ni or Co plating layer provided on the surface of the fin tube,
(2). A Zn-Ni alloy plating layer provided on the Ni or Co plating layer,
(3). A chromate film layer provided on the Zn-Ni alloy plating layer,
(4). An electrodeposition coating layer provided on the chromate film layer,
A fin tube for a fuel cooler of an automobile having a high heat-resistant and high corrosion-resistant film, comprising: 3. The fin tube for a fuel cooler of an automobile having a high heat and corrosion resistant coating according to claim 1, wherein the electrodeposition coating layer is formed by cationic electrodeposition coating.

Images