JPS63241133A - Heat exchanger made of aluminium - Google Patents

Abstract

PURPOSE:To elongate the period of anticorrosive durability and to improve the mechanical strength of the titled heat exchanger by forming it by combining main constituting members made of Al-Cu-Mn-Mg-Ti alloy of specified composition with auxiliary constituting members made of ordinary standard Al alloy by brazing. CONSTITUTION:Plates 131, 132 to be formed into tubes 141, 142,... of main constituting members of an evaporator 10 are made of the alloy containing by weight 0.2-0.6% Cu, 0.2-1.5% Mn, 0.05-0.5% Mg, 0.05-0.15% Ti, and the remaining part mainly consisting of Al. Corrugated fins 171, etc., of auxiliary members are formed by corrugating the thin plate of Al alloy of common JISA3003, etc., and are brazed to the upper and the lower plates 131, 132 forming tank parts 151, 152,... which are combined into the heat exchanger. By this constitution, a heat exchanger of high corrosion resistivity as well as excellent strength characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to aluminum heat exchangers mounted on automobiles, such as evaporators, condensers, and radiators, which are assembled and manufactured by brazing.

[Prior Art] Heat exchangers such as an evaporator, a condenser, and a radiator are installed in the refrigeration cycle of an air conditioner and the cooling cycle of engine cooling water, respectively.

Such heat exchangers, especially when installed in automobiles, etc.
There is a need to reduce its weight, and it is made of a lightweight metal alloy such as aluminum.

However, such aluminum alloys have insufficient corrosion resistance and strength, so in order to satisfy these corrosion resistance and strength characteristics, this type of heat exchanger is constructed from a relatively thick plate material.

In conventional aluminum heat exchangers, parts such as tubes and tanks through which refrigerant or water flow, which are the main components of the heat exchanger that require particularly high corrosion resistance and strength, are made of, for example, Al-Mn, AJ. An alloy such as -Cu)Al-Mg or a composite alloy thereof is used. All of the additive elements in these alloys form intermetallic compounds with aluminum, and have the effect of improving strength.

However, this intermetallic compound deteriorates corrosion resistance, and therefore, on the cooling water side in a highly corrosive environment, through holes are formed early due to corrosion, making it impractical from a practical point of view. The thickness of the main components that make up this heat exchanger is increased. In other words, it is difficult to reduce the weight.

[Problems to be Solved by the Invention] This invention has been made in view of the above-mentioned points. The main components that make up the required heat exchanger have excellent corrosion resistance and excellent strength characteristics, and are also lightweight so that they can be effectively installed in automobiles, etc. The present invention aims to provide an aluminum heat exchanger as described above.

Means for Solving Problem c] That is, in the aluminum heat exchanger according to the present invention, its main constituent parts are M n s CLl %Mg
Al-Mn −Cu − with Ti added together with other elements such as
It is constructed from an Mg-Ti-based aluminum alloy.

[Function] In the aluminum heat exchanger configured as described above, the main constituent parts are Mn, Cu, and aluminum.
By being made of an aluminum alloy to which Mg is added, its mechanical strength can be made excellent. Also, for this aluminum alloy,
Because it contains Ti, it prevents the uneven distribution of intermetallic compounds that degrade corrosion resistance caused by the above additive elements, making it possible to obtain a heat exchanger with excellent corrosion resistance and strength characteristics. It is what it is.

[Embodiments of the Invention] The present invention will be described in detail below. The aluminum heat exchanger according to the present invention is particularly installed in automobiles, and constitutes, for example, an evaporator, a condenser, or a radiator for cooling water in an air conditioner. A Drone cup type evaporator 10 is shown as one example.

This evaporator 10 is installed in the refrigeration cycle of an air conditioner installed in an automobile, and refrigerant gas is introduced through an inlet vibrator 11, and the refrigerant gas that has passed through the evaporator is discharged through an outlet vibrator 12. The refrigerant is then sucked into a refrigerant compressor driven by the engine.

This evaporator 10 has two plates 13 each.
By joining 1 and 132, a plurality of tubes 14+, 142, . . . , through which refrigerant gas passes, which are the main constituent members of this evaporator IO, are constructed. In this case, the tubes 141, 14 with the above-mentioned number of stages
Two plates 131 respectively constituting 2,...
．． At each end portion of tube 141 .
Tank portion 151.1 between each of 142, . . .
52, and the tank portions 151, 152, . . .
Inside are corrugated fins 171, . 172, . . . are set to be stored. This fin 172.172...
are constructed by bending a thin plate into a wave shape, and the tank portions 151, . It is attached by brazing to upper and lower plates 131, 132 forming 152, . Reference numeral 18 denotes an end plate that holds the laminated structure of the constituent members of the plurality of tubes 141, 142, .

Although not shown in the above figure, the plurality of tubes 141 , 142 , . Refrigerant gas is supplied through tube 141.1
42... in series to be guided to the exit vibe 12.

The constituent members of the evaporator IO configured in this way are:
It is entirely composed of aluminum alloy,
For example, when assembling by vacuum brazing, the material is selected as follows.

That is, the input vibrator 11, the output vibrator 12, the corrugated fins 171, 172, . . .
etc. are made of aluminum alloy as shown in the general J15A300B, whereas the plates 1-131, +32, . .・Constructed from an aluminum alloy with excellent corrosion resistance and strength characteristics. Specifically, 0.20W for aluminum
t/% Cu, 0.40w t/96 Mn, 0.2
0 wt/% Mg and 0.05 wt/% T1 are added, and further impurities include 0.15 wt/% Si and 0.15 wt/% Si.
It is configured to contain 15 wt/% of Fe.

Examples of the structure of the aluminum alloy constituting this main component are shown in Table 1 as Example 1, and there are other examples as shown in Examples 2 to 8 in Table 1.

The plates 131 and 132 are connected to the first
J I 5A4 on both sides of the plate of alloy of the composition indicated in the table
004 brazing material is 15% clad, and the plate thickness is 0.8 mm. In addition, the corrugated fins 171, 172, ... have a plate thickness of 0.1
It is made up of 6mm.

Such an evaporator 10 is assembled, for example, as follows. That is, first, each member is assembled into the state shown in Fig. 1, and then this state is held and set using a suitable jig, and the parts are cleaned with an organic solvent such as Tri-Clene solvent. , to remove oil from its surface.

Thereafter, it is heated for 13 minutes in a vacuum heating furnace at a temperature of 610° C. and a degree of vacuum of 5×10'5 mmHg. This heating causes the molten brazing material to flow over the surface of the aluminum base material, and the parts are simultaneously brazed together.

Here, the aluminum alloy constituting the main component is first
The composition shown in the table was chosen for the following reasons.

First, the strength is improved by adding Cu, and the potential of the alloy is made nobler. Therefore, A, i'-6, which is the solder for joining,
It becomes possible for one heavy metal to act as a sacrificial anticorrosion layer. If the amount of Cu is less than 0.2 wt/%, the above effect cannot be obtained sufficiently, and if the amount of Cu is less than 0.2 wt/%, the above effect cannot be obtained sufficiently.
If it exceeds wt/%, self-corrosion increases, and at the same time, the potential difference with the Al-S1 alloy layer, which is a sacrificial corrosion protection layer, becomes less than the appropriate value (target value 50 to 150 mV). As the braze corrodes and disappears, the braze begins to leak.

In addition, Mn is a necessary component to improve strength without deteriorating corrosion resistance, but when Mn is 0
．． If it is less than 2 Wt/%, it cannot exhibit the effect of improving this strength property, and if it exceeds 1.2 wt/%, Al-Mn compounds will be generated, resulting in a decrease in workability and corrosion resistance. I come to do it. Mg is also a component that improves strength, but its content is 0.
If it is less than 0.05 wt/%, there is no effect of improving this strength property. Moreover, if it exceeds 0.5wt/96, the formability and diffusion of Al-8L solder become intense, the alloy plate thickness decreases, the strength decreases, and the corrosion resistance also deteriorates.

By segregating the aluminum compound with Fe%S1 contained as an impurity, Ti suppresses the rate of corrosion occurrence points as much as possible and improves corrosion resistance. If the Ti content is less than 0.05 wt/%, no effect will be observed, and if it is 0.15 wt/% or more, it will exceed the solid solubility limit, and the effect will become saturated. .

C" and Z" both suppress the recrystallization of the alloy, and brazing is intended to reduce the strength loss during brazing. To achieve this purpose, Table 1 It is necessary to contain [1] in the range shown in .In other words, this element is added when the material becomes thinner and tends to buckle during brazing, in order to exhibit its effect. .

Furthermore, the reason why the content of F o s S l as an impurity is set to 0.2 wt/% or less is due to the effect of Ti, which is one of the characteristics of the aluminum alloy constituting the above-mentioned main component. However, by regulating the impurity port, the anti-corrosion effect is further ensured.

In the second example, an evaporator 10 is shown, but in addition, a radiator 20, which flows cooling water, as shown in FIG. Furthermore, in the condenser 30 through which the refrigerant flows as shown in FIG. A tank 23 is formed to store this cooling water.The water in this tank 23 is circulated through a tube 24. Corrugate fin 2 corresponds to 24 parts of this tube.
5 is provided.

Here, -L: g own tank 23 and tube 24 force (
This is the main component of the radiator 20, and the in/out lobe 21, 22 and the corrugated fins 25 are the net components.

The condenser 30 shown in FIG. 3 is constructed by folding and bending a flat drawn-out tube 31, which is the main component, and supplies refrigerant to the end of the tube 31. An inlet vibrator 32 and an outlet vibrator 33 are connected, and a corrugated fin 34 serving as a net component is provided between the folded tubes 31.

Figure 4 shows the static pressure burst strength and C of the heat exchanger as described above.
The results of evaluating corrosion resistance by ASS test (based on JISH8681) are shown. In this test, the first
In addition to each of the examples shown in the table, the comparative examples and conventional examples shown in the table above are shown, and as is clear from the test results, the alloy according to the present invention is different from the conventional J I 5A3003. Corrosion resistance is improved by about 10 to 30% compared to alloys. It was also found that the corrosion resistance life was approximately doubled.

] - In the description of the embodiment, corrugated fins 171, 172, . . ., and 25.3
4 is made of an aluminum alloy commonly designated as J I 5A3003. However, for this net component, an aluminum alloy, such as those shown in Examples 1 and 2 in Table 2, is used, which has a less noble electrode potential than the plate 1315132, which is the main component shown in the above embodiment. You may also do so.

The reason why the additive components for the aluminum of the net constituent members such as corrugated fibers were determined as shown in Table 2 is as follows. Mn is a component to improve strength, but if the Mn content is less than 0.2 wt/%, buckling of the fins may occur during assembly, and if it exceeds 1.5 wt/%, workability may deteriorate. It gets worse and productivity becomes worse. Zn sometimes evaporates during vacuum brazing and has no effect on the material, but the Mg-attached young material in the furnace becomes a Mg-Zn compound with a low flashing temperature, making it easier to clean. be. If Zn is less than 0.01 wt/%, the effect will not be exhibited, and if it is more than 0.5 wt/%, contamination in the furnace will become severe.

In addition, the impurities are S10.6wt/% or less, Fe
d, 3wt/% or less, CuO, 2wt/% or less, Mg
0. 05 wt/96 or less, other components 0.
0.05 wt/% or less, and the overall content is 0.15 wt/% or less. This is because if more impurities are added, the electrode potential becomes noble and the potential difference with the main component becomes inappropriate. This is because, for example, the sacrificial corrosion protection effect on the tube will not be recognized.

Such a phenomenon was confirmed by measuring the electrode potential of a test piece made of a predetermined alloy and heated in vacuum.

Electrode potential of fins made of JIS A3003 alloy, which is a conventional aluminum alloy (396Na
C12, M1 constant at room temperature) is -0, 85V (vs.

S, C, E), the potential of the alloy fin according to the two-leg example is -0.87 because impurities are suppressed despite the evaporation of Zn during vacuum heating. ～−
〇, it is 88V, which is low. As a result, for example, the current potential of the plates 131 and 132 is -0.83V, and the potential difference with the fins, which are the net constituent members, as shown in Table 2 is 40 to 50 mV.Therefore, a sacrificial corrosion prevention effect is fully expected. It is confirmed that it can be done.

The corrosion resistance of the aluminum heat exchanger constructed in this way was determined by the CASS test as shown in Figure 5, and compared to the case where conventional JISA 3003 alloy fins were used, the corrosion resistance of the example was The sacrificial corrosion protection effect of the alloy fins shown extends the service life by about 1.4 times.

Table 3 shows still other embodiments of net constituent members such as full gate fins, the main constituent members of which are made of aluminum alloys as shown in Table 1. In this embodiment, a Sn-based alloy is used for the corrugated fins, which are net constituent members, because vacuum brazing does not sometimes evaporate, lowers the potential, and impairs sacrificial corrosion protection.

The reason for limiting the Sn content of the net constituent members is
This is due to the following reasons, but Mn and zn
The details are the same as those in the embodiment shown in Table 2 above. Sn
It exerts a sacrificial corrosion protection effect by lowering the potential of the alloy and protects main components such as tubes, but if its content exceeds the upper limit, rolling workability decreases and self-corrosion increases. . In a state below the lower limit, the initial anticorrosion effect cannot be exhibited.

In order to confirm the effect of including So, 2396NaCi, PH
When the electrode potential was measured using the solution No. 7, the results were also listed in Table 6.

That is, by adding Sn, the electrode potential of this network member is reduced to -0.85V, the potential of the core material of the main component.
(vs, S, C, E), and it was confirmed that the sacrificial corrosion protection effect can be fully expected.

The corrosion resistance of the aluminum heat exchanger made in this way was evaluated by CASS test, as shown in Fig. 6. The exchanger is 1, conventional JI
Approximately 1% compared to using 5A3003 alloy fins
．． It can be confirmed that the life span can be extended by 5 to 2 times.

In the description of the embodiments so far, vacuum brazing has been described only for aluminum heat exchangers manufactured by the method, but vacuum brazing is currently being performed using fluoride-based flux in an N2 atmosphere. The present invention can also be applied to aluminum heat exchangers manufactured by the non-corrosive flux atmosphere brazing method.

[Effects of the Invention] As described above, in the aluminum heat exchanger according to the present invention, the corrosion-resistant life can be effectively extended, and the mechanical strength can also be improved. Therefore, it has become easier to make the thickness of the component parts thinner, and it has become possible to reduce the cost and weight, making it possible to effectively apply the heat exchanger especially to vehicles. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an aluminum heat exchanger according to the present invention, FIGS. 2 and 3 are diagrams each showing examples of other heat exchangers, and FIG. 4 is a diagram showing an example of an aluminum heat exchanger according to the present invention. FIG. 5 shows the state of evaluation of the characteristics of the alloy of the main component of the heat exchanger.
FIG. 6 and FIG. 6 are views showing evaluation states of alloys of sub-components of heat exchangers according to other embodiments, respectively. IO... Evaporator, 1315132... Plate (main component) 141, 142,..., 24
．． 31...Tube, 171, 172,...
25.34...Corrugate fin (sub-component), 2
0...Radiator, 30...Capacitor.

Claims (5)

[Claims] (1) 0.2-0.6wt/% Cu, 0.2-1.5
wt/% Mn, 0.05-0.5 wt/% Mg, 0
．． Main constituent members such as tubes and tanks made of alloys each containing 05 to 0.15 wt/% of Ti and the remainder mainly composed of Al, and sub-component members such as fins made of aluminum alloy according to normal standards. An aluminum heat exchanger, characterized in that the main component and the sub-component are assembled together by brazing. (2) The above main components further include 0.03 to 0.10
wt/% Cr, and 0.01-0.5 wt/% Z
The aluminum heat exchanger according to claim 1, wherein r is added. (3) Cu, Mn, Mg, T constituting the above main constituent members
The aluminum constituting the portion other than i contains unavoidable impurities, and the scope of the claim is such that the amount of Fe and Si among these impurities is 0.2 wt/% or less The aluminum heat exchanger according to item 1. (4) The fin, which is the above-mentioned secondary member, has a weight of 0.2 to 1.5wt.
/% Mn and 0.01 to 0.5 wt/% Zn, and this aluminum alloy contains 0.6 wt of Si as an impurity.
/% or less, Fe is 0.3wt/% or less, Cu is 0.2w
Mg is set to be 0.05 wt/% or less, other components are set to 0.05 wt/% or less, and the total impurity amount is 0.15 wt/% or less. The aluminum heat exchanger according to claim 1, wherein the aluminum heat exchanger is configured to have the following configuration. (5) The fin serving as the above-mentioned sub-component has a diameter of 0.2 to 1.5
wt/% Mn, 0.01-0.5 wt/% Zn, 0
．． 2. The aluminum heat exchanger according to claim 1, wherein the aluminum heat exchanger is constructed using an alloy containing 0.02 to 0.06 wt/% Sn and unavoidable impurities, with the remainder being Al.