JPH0219390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stacked evaporator, in particular,
Regarding prevention of condensed water scattering.

Generally, as an evaporator for car coolers,
In order to improve performance and reduce costs, we created a tube element in which a pair of dish-shaped tube plates are joined face-to-face to form a flat refrigerant evaporation chamber inside, and air is defined between adjacent tube elements. A laminated type evaporator has been proposed in which a large number of bellows-shaped corrugated fins that define passages are welded together alternately. There is a problem in that condensed water produced when the temperature drops below the dew point (generally referred to as condensed water) scatters and enters the vehicle interior, impairing the air-conditioned environment.

The present inventors investigated the cause of the above-mentioned condensed water and obtained the following considerations.

First, as a premise, hydrophilicity, which indicates the compatibility of the surface of an object such as a metal with liquids such as condensed water (hereinafter referred to as water), will be explained. When water is dropped onto the surface of an object, water droplets are formed due to the surface tension of the water, and the shape of these water droplets varies depending on the condition of the surface of the object. In other words, as shown in Figures 6A and B, in a case like Figure 6A, the surface of the object is said to have good hydrophilicity, and in a case like Figure 6B, the surface of the object is considered to have good hydrophilicity. considered bad. usually,
The degree of hydrophilicity is called the contact angle θ between the object surface and the water droplet surface, that is, the angle between the water droplet and the tangent line of the water droplet at any contact point between the object surface and the water droplet surface. Under the same conditions, a mirror-like object surface usually has poor hydrophilicity, and an object surface with a large surface roughness, such as a satin finish, has good hydrophilicity. Conventionally, the corrugated fins of a laminated evaporator are formed from aluminum material by roll rolling, and therefore have a mirror-like surface and extremely poor hydrophilicity. Therefore, the condensed water adhering to the fins takes on an almost spherical shape as shown in Figure 6B, and does not blend into the surface of the fins, and increases the ventilation resistance itself, making it difficult for air to pass through the fins. It becomes easy to be blown away by the current.

In particular, as the evaporator is used over time, hydrophobic components (components that deteriorate hydrophilicity) in the atmosphere, such as floating oil, adhere to the surfaces of the fins and tubes, and the hydrophilicity of the surfaces deteriorates. Therefore, the scattering phenomenon of condensed water tends to become more pronounced.

The present invention was made by confirming the above-mentioned water splash principle through experiments, and consists of forming corrugated fins from a sheet material consisting of a core material surface covered with brazing filler metal, thereby reducing the amount of condensation that adheres to the surface of the fins. The purpose is to improve the compatibility with water, make the condensed water take on a flat shape, and prevent the condensed water from scattering.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are diagrams showing one embodiment of the present invention. First, to explain the structure, as shown in FIG. 1, a stacked evaporator has a large number of tube elements 1 arranged at intervals of P, each of which has a pair of left and right tube sheets 10, 10 joined to face each other to form a refrigerant passage inside. However, a bellows-shaped corrugated fin 7 is disposed between these tube elements, and plates 12, 12a are further joined to both left and right ends. This evaporator as a whole has left and right end walls and upper and lower end walls shielded from the outside, and intake air for cooling is introduced in a direction perpendicular to the plane of FIG. It's summery. As shown in FIGS. 2 and 3, the tube element 1 includes a refrigerant evaporation chamber 3, which is generally flat, formed by a pair of tube plates 10, 10 whose inner surfaces bulge outward, and an upper part of the refrigerant evaporation chamber 3. Refrigerant outlet chamber 4 communicating with
The outer wall of the evaporation chamber 3 cooperates with the outer wall of another tube element 1 to form an air passage 6, and a corrugated fin is formed between the two outer walls. 7 is held in close contact. In this embodiment, a diffusion passage 2 is formed in the evaporation chamber 3 by a large number of protrusions formed by bulging the inner surfaces of a pair of tube sheets 10, 10 inward. The shape of each tube sheet 10 is a vertically long approximately rectangular shape, and is symmetrical vertically and horizontally, and this peripheral edge 14
The continuous annular surfaces of the wires are brought into contact with each other and soldered together. The outlet chamber 4 is provided with a through hole 18 in the center and through holes 19, 19 on both sides thereof. Similarly, the entrance chamber 5 is also provided with a through hole 18a and through holes 19a, 19a. The end plates 12, 12a are also similar to the tube sheet 10, except that the through holes are not provided. As shown in FIGS. 1, 3, and 4, the corrugated fin 7 is
A strip plate having the same width as the tube sheet 10 is bent into a corrugated or bellows shape, and the bent portion 7b is tightly soldered to the outer wall portion of the evaporation chamber 3 of the tube sheet 10. corrugate fin 7
A louver 8 is formed by cutting and bending a flat abdomen 7a that is located between the tube plates 10 and 10 and partitions the air passage 6 into upper and lower parts. Exchange of intake air between the passages is provided.

The laminated evaporator according to the above structure is manufactured by making each component have high thermal conductivity, for example,
A thin metal plate such as aluminum is formed by press working, the tubular surface is coated with brazing material in advance, and after each component is assembled, it is held in the assembled state with a jig (not shown) and heated in a predetermined atmosphere. Then, the brazing material is melted and the contact parts are welded to each other to fix the assembled state.

As shown in FIG. 5, the corrugated fin 7 is formed of a sheet material 21 made of a core material 22 made of aluminum, for example, and a skin material 23 made of a brazing material bonded to the surface (the entire surface including the back surface) of the core material 22 made of aluminum. The skin material 23 on one side of the sheet material 21 is the sheet material 2
A hydrophilic coating layer 7c having a thickness of 5% or less, preferably 2-3% of the total thickness of the corrugated fin 7 and having a surface with good hydrophilicity is formed on the surface of the corrugated fin 7. That is, this hydrophilic coating layer 7c is
The skin material 23 made of brazing material is melted and solidified by the heat treatment described above, thereby increasing its surface roughness.
Therefore, it has extremely good hydrophilicity.

Here, specific examples of the structures of the core material and the skin material are as follows. The core material of the sheet material 21 is made of aluminum or its alloy, and its thickness is usually 0.14 mm to 0.18 mm, for example, according to JIS
Preferably, alloy No. 1050 or No. 3003 is used, depending on the specification. The skin material is formed from an Al--Si alloy system, and it is preferable to use, for example, a No. 4000 brazing material such as No. 4004 or No. 4043 according to JIS standards.

Incidentally, a brazing filler metal is crimped onto the surface of the tube sheet 10 forming the tube element 1 before assembly, but the thickness of this brazing filler metal on one side of the tube element is usually the same as that of the entire tube sheet. thick
It has become around 10%. The reason why the thickness of the brazing material of the tube sheet 10 is set to be large is that it is necessary to weld the constituent members together by melting and solidifying the brazing material. On the other hand, the reason why the thickness of the sheet material 21 constituting the corrugated fin 7 is set to a small value of 5% or less of the thickness of the sheet material as described above is that this brazing material is This is not intended to be mutually welded, but because it is sufficient to form the hydrophilic coating layer 7c as described above on the surface of the corrugated fins 7, it can be made extremely thin.

Note that after the stacked evaporator is assembled, it is entirely subjected to trichlene degreasing treatment, and further, after that treatment, it is subjected to chromic acid coating treatment. Therefore, the entire surface of the laminated evaporator is coated with a chromic acid coating, and the surface of the hydrophilic coating layer 7c of the corrugated fin 7 is also coated with this chromic acid coating, further improving hydrophilicity. ing.

Next, the operation of the stacked evaporator according to the above configuration will be explained. Each tube element 1
The refrigerant inlet chamber 5 communicates with each other through the through hole 18a, and the refrigerant outlet chamber 4 similarly communicates with each other through the through hole 18, and only the tube elements 1 at the left and right ends are closed by the end plates 12, 12a. There is. The evaporator is connected to the refrigerant circuit of the refrigeration cycle through the inlet chamber 5 and outlet chamber 4 through conduits 15 and 16, and the liquefied refrigerant introduced into the refrigerant inlet chamber 5 enters the evaporation chamber 3. Diffusion channel 2
It reaches the outlet chamber 4 while being diffused and mixed by the water. The refrigerant rising in the evaporation chamber 3 in this way is vaporized while sucking the heat of the intake air through the corrugated fins 7 or directly through the tube plate 10,
After reaching the outlet chamber 4, it is sucked from there into a compressor (not shown). On the other hand, the intake air for cooling introduced into the passage 6 by a block (not shown) flows through the tube elements 1, 1 in the direction of the arrows in FIGS.
The liquid flows between the outer walls of the corrugated fins 7, and a part of the liquid passes through the louvers 8 and is cooled while changing the flow to an adjacent passage.

At this time, moisture in the air comes into contact with the corrugated fins 7, becomes below the dew point temperature and condenses, and adheres to the surface of the corrugated fins 7. , brazing material 23 of sheet material 21
is covered with a hydrophilic coating layer 7c formed by melting and solidifying, so the condensed water that adheres to this layer is
As shown in Figure A, the contact angle is small. (According to experiments, it was 15 to 20 degrees.) It has a flat curved surface form. Since the condensed water having such a flat curved surface shape has low airflow resistance, it is not easily separated from the surface of the corrugated fin 7 by air blowing. Furthermore, as mentioned above, the surface of the hydrophilic coating layer 7c has a finely uneven surface, so it retains its hydrophilicity well, and if it has such a flat shape, Even if condensed water becomes swollen, corrugate fin 7
At the bent portion 7b, there is almost no possibility of bridging and closing the bent portion 7b. Therefore, even if the condensed water becomes swollen, it is prevented from leaving the corrugated fin 7 by the air flow. In addition, the finely uneven surface of the hydrophilic coating 7c has the property of retaining condensed water well and causing the condensed water to flow down along the surface due to its own weight (the group of unevenness is thought to form a kind of waterway). ), the condensed water flows down the corrugated fin 7 while remaining attached to the surface. This flowing water is discharged to the outside from a drain port (not shown) that is normally provided below the corrugated fin 7. Therefore, the problem of condensed water scattering from the evaporator and entering the passenger compartment on the airflow can be prevented.

Incidentally, in order to confirm the water splash prevention effect after long-term use, a sample of the corrugated fin according to the present invention and a conventional sample were tested under the same conditions.
When the contact angle of water droplets dropped on the surfaces of both samples was measured using a goniometer after being left indoors for 1000 hours, in the case of the present invention, the contact angle was 15 to 20 degrees, which is almost the same as when it was left. In contrast, in the conventional case, the contact angle was 100 degrees. As a result,
In the present invention, it has been confirmed that the water splash prevention effect does not deteriorate even after years of use.

In addition, in the case of the present invention, the sample is based on the JIS standard.
A core material made of No. 1050 aluminum is pressure-coated with a brazing material made of No. 4004 Al-Si alloy according to JIS standards to obtain a sheet material 21 having a predetermined hydrophilic coating layer. Corrugated fins formed by triclene degreasing and chromic acid coating were used. In addition, the conventional sample used a corrugated fin made of the same pure aluminum fin material (JIS standard alloy number 1050) as the core material of the present invention, which was subjected to trichlene degreasing and chromic acid coating treatment. .

Since we adopted a structure in which the surfaces of the tube element and corrugated fin are coated with brazing filler metal, bonding of each component and formation of a hydrophilic coating layer on the corrugated fin can be performed in one process (heating process). , easy to manufacture.

In addition, since the brazing material coated on the corrugated fin side is thinner than the brazing filler metal coated on the tube element side, the bonding of each component is reliable, and the surface of the corrugated fin is highly hydrophilic. A hydrophilic coating layer is formed, which can prevent condensed water from scattering from the evaporator and entering the vehicle interior through airflow.

[Brief explanation of drawings]

Figure 1 is a front view showing one embodiment of the present invention, Figure 2 is a front view showing one embodiment of the present invention;
The figure is a sectional view taken along the line of Figure 1, and Figure 3 is a cross-sectional view taken along the line of Figure 1.
Figure - Sectional view along the line, Figure 4 is Figure 2 -
5 is an enlarged partial sectional view of the corrugated fin, and FIGS. 6A and 6B are explanatory views for explaining hydrophilicity. 1...tube element, 3...refrigerant evaporation chamber, 6
...Air passage, 7. Corrugated fin, 10. Tube plate, 21. Sheet material, 22. Core material, 23. Skin material (brazing material).

Claims (1)

[Claims] 1. A tube element that forms a flat refrigerant evaporation chamber inside by joining a pair of dish-shaped tube sheets facing each other;
In a stacked evaporator formed by closely welding a large number of bellows-shaped corrugated fins that horizontally partition an air passage defined between adjacent tube elements, each surface of the tube element and the corrugated fin is 1. A laminated evaporator characterized in that the brazing material is coated on the corrugated fin side, and the brazing filler metal coated on the corrugated fin side is thinner than the brazing filler metal coated on the tube element side.