JPS63213797A - Heat exchanger for automobile - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of fins, lighten the weight of the fins, and maintain excellent heat exchanging characteristic for a long time by a method wherein the fins are formed of Cu or Cu alloy-made thin strips, to the surfaces of which Ni, Co or their alloys are applied. CONSTITUTION:In a heat exchanger which is constituted in such a manner that copper-made core 3 is formed by attaching fins 2 between tubes 1 and seat plates 4a, 4b are installed on both ends of the tubes 1 of the core 3 and tanks 5a, 5b are attached on the seat plates, the fins 2 are formed of Cu-based metal strips 10 on the surfaces of which coating layers consisting of Ni, Co or their alloys (the rest is abbreviated as Ni, etc.) and having a thickness of 0.05-3mu are placed. As for Ni, etc., for example, Ni, Co are enumerated at first, and then such alloys as Ni-Co, Ni-P, Co-B, Ni-Co-P, Ni-Cu, Ni-Sn, Ni-Zn, Ni-Cb, etc., are enumerated. Any of these alloys containing 50% or more Ni or Co is used.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a heat exchanger for automobiles, and in particular, it improves the corrosion resistance of the fins, satisfies weight reduction and economic efficiency as a heat exchanger, and provides good heat exchanger. This allows the replacement function to be maintained for a long period of time.

[Conventional technology]

Generally, automobiles use radiators for engine cooling and heaters for air conditioning, and these heat exchangers each have fins installed between multiple tubes through which a heat exchange medium (hereinafter abbreviated as medium) flows. A core is formed, seat plates are provided at both ends of the core tube, and a tank is attached to the core. For example, in a radiator, as shown in Figure 1, a plurality of vertical tubes (1) through which the medium flows are arranged in parallel, and corrugated fins (2) are placed between each tube (1).
is attached to form a core (3), seat plates (4a), (4b) are provided at both ends of the tube (1) of the core (3), and tanks (5a), (5b) are attached. Usually, the tube (1) is made of brass, and the fin (2) is made of Cu or CLI alloy with high thermal conductivity and has a thickness of 0.0
2-0. A thin strip of o6m processed into a corrugated or looper shape is used, and a fin (2) is attached to the tube (1).
are attached by soldering to form a copper core (3). In the figure, (6) and (7) are the media entrance and exit, (
8) and (9) indicate the medium inlet and outlet.

The fin is the most important part that directly determines the heat exchange characteristics, and the Cu or Cu alloy strip (hereinafter abbreviated as Cu-based strip) used as the fin material has the ability to withstand heating conditions such as soldering during the radiator assembly process. In order to maintain a constant strength, Sn, Cd, A(J
A dilute alloy containing a small amount of SPb or the like is used.

The most widely used is Cu-0,15%Sn
It is a -0.01% P alloy and has the properties of a tensile strength of 35 Kg/mm2, a semi-softening temperature of 135°C, and an electrical conductivity of 85%lAC3.

[Problem that the invention seeks to solve]

In recent years, it has become common practice in snowy regions to spray large amounts of salts such as table salt as a snow melting agent, and a decline in heat dissipation due to corrosion and wear of the fins due to these salts has become a problem, especially in radiators. has been done. There is a strong demand for lightweight one-way vehicles, and there is also a desire for lightweight heat exchangers for automobiles.
It is necessary to make the wall thickness as thin as possible, and the above-mentioned measures against salt damage have become an even more serious problem. In order to solve this problem, attempts have been made to form a corrosion-resistant coating film, but a thick film of 10 μm or more is essential to prevent salt damage, which is a serious disadvantage in terms of heat dissipation and weight reduction. We also improved the copper alloy for fins,
Attempts have been made to improve corrosion resistance, but in order to improve corrosion resistance 10% or more of Ni is required, resulting in a significant decrease in thermal conductivity.In particular, in the C1-10%Ni alloy, the electrical conductivity is 9%. The AC value is about 3, and it cannot be used for fins.

(Means for Solving the Problems) In view of this, and as a result of various studies, the present invention has developed a heat exchanger for automobiles that can withstand the above-mentioned salt damage conditions, is lightweight, and satisfies the requirements of economical efficiency. In a heat exchanger, a copper core is formed by attaching fins between a plurality of flowing tubes, seat plates are provided at both ends of the duplex of the core, and a tank is attached. It is characterized by being formed of a Ctl-based strip coated with these alloys to a thickness of 0.05 to 3 μm.

That is, as shown in FIG. 1, the present invention includes installing fins (2) between tubes (1) to form a copper core (3), and seat plates (4a) at both ends of the tube (1) of the core (3). ), (4
b) In the heat exchanger equipped with tanks (5a) and (5b), the fins (2) are coated with Ni, Co or alloys thereof (hereinafter abbreviated as Ni etc.) on the surface as shown in Figure 2. C provided with a coating layer (11) with a thickness of 0.05 to 3μ consisting of
It is formed of U-based strips (10). Examples of Ni include Ni, Co, xr −Co, N+ −
p, Go-B, Ni-Go-P, Ni-Cu, N
An alloy such as i-3n, Ni-Zn, or Ni-Cd, each containing 50% or more of Ni or Go, is used.

[Effect]

However, in the present invention, the purpose of coating the surface of the Cu-based strip with Ni, etc. is to improve the corrosion resistance of the fin, and the reason why the coating thickness of Ni, etc. is set to 0.05 to 3 μm is 0.05 μm to 3 μm.
If it is less than 0.05μ, sufficient corrosion resistance cannot be obtained, and if it exceeds 3μ, the thermal conductivity of the fin as a whole decreases, and in order to obtain a certain heat dissipation characteristic, the fin must be thickened, which not only becomes uneconomical but also increases heat resistance. This is because it goes against the demand for lighter weight exchangers. Coating layers such as Ni have greater mechanical strength and heat resistance than CIJ-based strips, and when thinning fins for the purpose of lightweighting and high performance, the skin effect strengthens the fins and particularly improves bending strength. At the same time, it is possible to prevent abnormal softening during high-temperature work such as soldering.

Since the surface of the Cu-based strip can be coated with Ni or the like in advance, it does not impair productivity. For example, a rolled Cu-based strip may be coated with Ni or the like by electroplating, chemical plating, vapor deposition, or the like, and may be finished by rolling, if necessary. In this way, Cu coated with Ni etc.
The strings are corrugated to form fins. This may be combined with a tube through which the medium flows, and a copper core may be formed by soldering or the like.

The effects of the present invention will be explained below with reference to Examples.

〔Example〕

Tough pitch 00 strips having a thickness of 0.038 # were used and plated with Ni or the like using the following bath to produce fin materials for the heat exchanger of the present invention shown in Table 1. This was heat treated in the atmosphere at a temperature of 320'C for 3 minutes, simulating the assembly process of a radiator, and then its strength, electrical conductivity and corrosion resistance were examined. These results are also listed in Table 1 in comparison with conventional heat exchanger fin materials.

In addition, the corrosion resistance was determined after spraying 5% salt water based on JIS Z3721 and leaving it in the atmosphere for 2 hours and 22 hours for 1 month.
Corrosion was removed by ultrasonic treatment in a 0% H2S04 solution, and corrosion reduction was measured.

Ni plating bath Ni (303NH2)2 500g/j! Ni
C120g/I H3BO230g/l Bath temperature 45℃ Current density 5A/dm2Ni-10%Go plating bath Ni SO4240'j/I C080415g/1 NiCJl 30q/IH
380330g/I P8 3.2 bath
Temperature: 45°C Current density
3.5A/dm2Ni -7%P plating bath Ni SOa 200g/lNi
C1z 15g/iH3PO32
59/I H380330g/i PH3,2 Bath temperature 30℃ Current density 3A/dm2 As is clear from Table 1, the fin material of the heat exchanger of the present invention whose surface is coated with Ni etc. to a thickness of 0.05 to 3μ It can be seen that NO.2 to NO.8 can all provide a large anticorrosion effect with a small decrease in electrical conductivity.

On the other hand, Comparative Fin Material No. 0.1 and Conventional Fin Material No. in which the coating thickness of Ni or the like is less than 0.05μ.

9, NO, 11, No. 12 all have significantly poor corrosion resistance, and conventional fin material NO.10 has excellent corrosion resistance, but has low electrical conductivity and inadequate thermal conductivity. I understand.

〔Effect of the invention〕

In this way, the heat exchanger of the present invention has zero Ni etc. on the surface of the fins.
By forming the fins with Qu-based strips coated with a thickness of 0.5 to 3μ, the corrosion resistance of the fins is greatly improved, light chains are achieved, and economic efficiency is satisfied, and good heat exchange characteristics are maintained for a long period of time. It can produce remarkable effects.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of an automobile radiator, and FIG. 2 is a sectional view showing an example of the fins of the heat exchanger of the present invention. 1 .....Tube 2 .....Fin 3 .....Core 4a, 4b...Seat plate 5a, 5b... Tank

Claims (1)

[Claims] (1) In a heat exchanger in which a copper core is formed by attaching fins between a plurality of tubes through which a heat exchange medium flows, seat plates are provided at both ends of the tubes of the core, and a tank is attached. A heat exchanger for an automobile, characterized in that it is formed of a Cu or Cu alloy thin strip whose surface is coated with Ni, Co, or an alloy thereof to a thickness of 0.05 to 3μ.