JPH0534085A - Heat exchanger and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a heat exchanger capable of improving heat transfer efficiency while securing the purity of refrigerant. CONSTITUTION:Heat exchanging outer tubes 2 are penetrated through a multi- tude of parallel heat dissipating fins 1, then, the heat exchanging outer tubes 2 are expanded to increase the closely contacting property between the heat dissipating fins 1 and the heat exchanging outer tubes 2. Heat exchanging inner tubes 3 are fitted into the expanded heat exchanging outer tubes 2, then, hoses 4A, 4B, 4C are connected to the ends of the heat exchanging outer tubes 2. Refrigerant is supplied from the hose 4A and is discharged from the hose 4C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for radiating the heat of a refrigerant in a heat exchange pipe penetrating a large number of heat radiation fins arranged in parallel from the heat radiation fins and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a heat exchanger of this type, as shown in FIG.
It is common to have a structure in which two are joined through. Since the heat conductivity of copper is higher than that of aluminum, it is preferable that the heat radiation fin is made of copper, but aluminum is used as the large number of heat radiation fins 11 because aluminum is advantageous in terms of cost. On the other hand, it is preferable to use a copper pipe as the heat exchange pipe 12, which is not as many as the heat radiation fin 11. However, for example, when a heat exchanger using a copper heat exchange pipe is used for cooling the oscillation part of a laser beam machine that requires cooling with pure water, copper ions flow out into the water from the heat exchange pipe. Pure water cannot be maintained. Stainless steel is optimal for maintaining the purity of such a refrigerant.

[0003]

The heat exchange pipe 12 is inserted into the insertion hole 11a formed in the heat radiation fin 11, and the diameter of the insertion hole 11a is slightly larger than the outer diameter of the heat exchange pipe 12. There is. The size of the diameter is set because it is necessary to provide a large number of heat radiation fins 11 arranged in parallel with each other so as to allow a plurality of heat exchange pipes 12 to pass through without difficulty. Due to the size relationship between the outer diameter and the diameter of the insertion hole 11a, the heat exchange pipe 1
2 and the radiation fin 11 have poor adhesion. Heat exchange pipe 1
The adhesiveness between the heat radiation fins 2 and the radiation fins 11 greatly affects the thermal conductivity, and the heat exchange efficiency is reduced. If the heat exchange pipe 12 is made of soft copper, it is possible to increase the adhesion by applying pressure to the inner surface of the pipe to expand the pipe, but in the case of hard stainless steel, this pipe expansion is impossible. Therefore, it is necessary to weld or bond the radiation fins 11 and the heat exchange pipe 12 made of stainless steel in order to enhance the adhesion, which complicates the manufacturing process and is disadvantageous in cost.

An object of the present invention is to provide a heat exchanger capable of improving the heat exchange efficiency while ensuring the purity of the refrigerant, and a method for manufacturing the heat exchanger.

[0005]

To this end, according to the first aspect of the present invention, a heat-exchange inner tube, which is in contact with a refrigerant, is formed by penetratingly joining a large number of heat-radiating fins in parallel with a heat-exchange outer tube made of a soft metal. A heat exchanger was constructed by penetrating and joining the outer tube for heat exchange.

According to the second aspect of the invention, the heat exchange outer tube made of soft metal is penetrated through a large number of heat radiation fins arranged in parallel,
Pressure is applied to the inner surface of the heat exchanging outer tube to expand it, and lubricating oil is adhered to at least one of the inner surface of the heat exchanging outer tube and the outer surface of the heat exchanging inner tube in contact with the refrigerant for heat exchange. After the expansion of the outer pipe for application and the adhesion of the lubricating oil, the inner pipe for heat exchange is fitted and joined in the outer pipe for heat exchange.

According to the third aspect of the present invention, the linearity of the heat exchange outer tube is increased by inserting the linearity imparting rod into the heat exchange outer tube after the heat exchange outer tube is expanded and the lubricating oil is attached. The straightening rod was removed from the outer tube for heat exchange, and then the inner tube for heat exchange, which was in contact with the refrigerant, was fitted into the outer tube for heat exchange to be manufactured.

[0008]

[Function] It is the heat exchange inner tube that directly contacts the refrigerant,
The heat of the refrigerant conducted to the heat exchange inner pipe is conducted to the heat exchange outer pipe via the contact portion between the heat exchange inner pipe and the heat exchange outer pipe. The heat conducted to the heat exchange outer tube is transferred to the heat radiation fin via the contact portion between the heat exchange outer tube and the heat radiation fin.

If stainless steel or titanium is used for the heat exchange inner tube, no chemical reaction occurs between pure water as the refrigerant and the heat exchange inner tube, and the purity of the refrigerant is ensured. That is, as the material of the heat exchange inner tube, a material that does not cause a chemical reaction with the refrigerant used can be arbitrarily selected.

The adhesion between the heat radiating fin and the heat exchanging outer tube is improved by expanding the heat exchanging outer tube made of a soft metal such as copper or aluminum. Good thermal conductivity.

The expansion of the heat exchange outer tube penetrating the large number of heat radiation fins is performed by hydraulic pressure, hydraulic pressure, or spherical fitting. After the lubricating oil is attached to the inner surface of the heat exchanging outer tube or the outer surface of the heat exchanging inner tube thus expanded, the heat exchanging inner tube is fitted into the heat exchanging outer tube. Due to the presence of the lubricating oil, it is easy to fit the heat exchanging inner tube into the heat exchanging outer tube, and moreover, the adhesion between the heat exchanging inner tube and the heat exchanging outer tube is compensated by the lubricating oil. That is, if an air layer is present between the inner tube for heat exchange and the outer tube for heat exchange, the thermal conductivity is lowered, but if the air layer is replaced by an oil layer, the thermal conductivity is improved.
A heat conductive grease is particularly preferable as the lubricating oil.

Although it is difficult to impart linearity to the inner surface of the outer tube for heat exchange by expanding the tube by hydraulic pressure, hydraulic pressure, or spherical fitting, it is possible to expand the inner tube of the outer tube for heat exchange and apply the lubricating oil to the outer tube for heat exchange to form a straight line. By inserting the property imparting rod, it is possible to easily impart linearity to the inner surface of the heat exchange outer tube. By imparting linearity to the inner surface of the heat exchanging outer tube, the heat exchanging inner tube can be fitted more easily, and moreover, the adhesion between the inner surface of the heat exchanging outer tube and the outer surface of the heat exchanging inner tube is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the entire heat exchanger. A plurality of heat radiation fins 1 arranged in parallel are provided with a plurality of heat exchange outer tubes 2.
Are penetrated, and the heat exchange inner tubes 3 are fitted into the respective heat exchange outer tubes 2. Both ends of each heat exchange inner pipe 3 project from the heat exchange outer pipe 2, and hoses 4A, 4B, 4C are connected to the protruding ends of the heat exchange inner pipe 3. In FIG. 1, the hoses 4A to 4C are simply shown by chain lines. The refrigerant is supplied from the hose 4A and discharged from the hose 4C. 5 is a suction type cooling fan.

The radiation fin 1 is made of aluminum, the heat exchange outer tube 2 is made of copper, and the heat exchange inner tube 3 is made of stainless steel.
In this embodiment, pure water is used as the refrigerant. FIG. 7 shows a joined state between the heat radiation fin 1 and the heat exchange outer tube 2 and a joined state between the heat exchange outer tube 2 and the heat exchange inner tube 3. The heat exchange outer tube 2 is inserted into an insertion hole 1 a formed in the heat radiation fin 1.

FIG. 2 shows a state in which a plurality of heat exchange outer tubes 2 are inserted through a large number of heat radiation fins 1. Diameter E of insertion hole 1a
Is slightly larger than the outer diameter of the heat exchange outer tube 2. In the inserted state of FIG. 2, the adhesion between the radiation fins 1 and the heat exchange outer tube 2 is poor, and in this inserted state the radiation fins 1
The thermal conductivity at the joint between the heat exchange outer tube 2 and the heat exchange outer tube 2 is low.

As shown in FIGS. 3 and 4, tube-expanding spheres 6 and 7 are used to enhance the thermal conductivity at the joint between the radiation fin 1 and the heat exchange outer tube 2. The diameter d ₁ of the tube-expanding sphere 6 in FIG. 3 is slightly larger than the inner diameter d ₀ of the heat exchange outer tube 2 before the tube expansion. The tube-expanding sphere 6 is inserted from one end of the heat exchange outer tube 2 to the other end. By this insertion, the inner diameter of the heat exchange outer tube 2 is expanded to the diameter d _{1 of the} spherical body 6.

The diameter d ₂ of the tube expanding sphere 7 in FIG. 4 is slightly larger than the inner diameter d ₁ of the heat exchange outer tube 2 in FIG. Similar to the tube expanding sphere 6, the tube expanding sphere 7 is inserted from one end of the heat exchange outer tube 2 to the other end. By this insertion, the inner diameter of the heat exchange outer tube 2 is expanded to the diameter d _{2 of the} sphere 7 over the entire length. That is, in this embodiment, the heat exchange outer tube 2 is expanded in two stages by using two kinds of expansion spheres 6 and 7 having different diameters. Due to this two-stage expansion, the outer diameter of the heat exchange outer tube 2 becomes larger than the diameter E of the insertion hole 1a, and the outer peripheral surface of the heat exchange outer tube 2 comes into close contact with the peripheral edge of the insertion hole 1a. This close contact improves the thermal conductivity between the heat exchange outer tube 2 and the heat radiation fin 1. The expansion of the heat exchange outer tube 2 and the heat exchange inner tube 3 to enhance the adhesion is much easier than the welding or adhesion method.

After expanding the entire length of the heat exchanging outer tube 2, the tube expanding spheres 6 and 7 are pulled out from the heat exchanging outer tube 2. When the tube is expanded by inserting the spheres 6 and 7, the spheres 6 and 7 can be easily inserted and withdrawn, and the adhesion between the heat exchange outer tube 2 and the radiation fins 1 is good. However, it is difficult to move the spheres 6 and 7 in a completely straight line, and it is impossible to straighten the inner peripheral surface of the heat exchange outer tube 2 by expanding the spheres 6 and 7. The linearity of the inner peripheral surface of the heat exchanging outer tube 2 determines the ease of insertion of the heat exchanging inner tube 3 and the adhesion between the inner peripheral surface of the heat exchanging outer tube 2 and the outer peripheral surface of the heat exchanging inner tube 3. It depends.

A linearity imparting rod 8 is inserted into the heat exchange outer tube 2 as shown in FIG. 5 in order to obtain linearity of the inner peripheral surface of the heat exchange outer tube 2. The diameter of the linearity imparting rod 8 is the same as the diameter d ₂ of the tube expanding sphere 7, and the linearity imparting rod 8 is
Is about half the length of the heat exchange outer tube 2. The outer periphery of the insertion end of the linearity imparting rod 8 is tapered,
The ease of insertion into the heat exchange outer tube 2 is achieved.

When the linearity imparting rod 8 is inserted into the heat exchanging outer tube 2, lubricating oil is applied to the peripheral surface of the linearity imparting rod 8 or the inner surface of the heat exchanging outer tube 2. By applying the lubricating oil, the linearity imparting rod 8 can be smoothly inserted. When the linearity imparting rod 8 is inserted into the heat exchange outer tube 2, the inner peripheral surface of the heat exchange outer tube 2 becomes straight over the entire length.

After imparting linearity to the heat exchange outer tube 2 and pulling out the linearity imparting rod 8, the heat exchange inner tube 3 is fitted into the heat exchange outer tube 2 as shown in FIG. The outer diameter of the heat exchange inner tube 3 is the same as the diameter d ₂ of the linearity imparting rod 8.
The outer peripheries of both ends of the heat exchange inner pipe 3 are tapered to facilitate insertion into the heat exchange outer pipe 2 and connection of the hoses 4A, 4B, 4C to the heat exchange inner pipe 3. There is.

When the heat exchanging inner tube 3 is inserted into the heat exchanging outer tube 2, lubricating oil is applied to the outer peripheral surface of the heat exchanging inner tube 3 or the inner peripheral surface of the heat exchanging outer tube 2. This lubricating oil, together with the linearity of the heat exchange outer tube 2, facilitates the insertion of the heat exchange inner tube 3.

Diameter of linearity imparting rod 8 and inner tube 3 for heat exchange
Since the outer diameter of the heat exchange inner tube 3 is the same as the outer diameter of the heat exchange outer tube 2 as shown in FIG. Adhesion with the inner surface of is high. Even if there is a clearance between the outer peripheral surface of the heat exchanging inner tube 3 and the inner peripheral surface of the heat exchanging outer tube 2, the lubricating oil fills this clearance and there is no room for air to enter. The presence of the air layer greatly hinders heat conduction, but liquid or viscous liquid lubricating oil has significantly higher heat conductivity than gas. Therefore, by interposing the lubricating oil between the inner peripheral surface of the heat exchanging outer tube 2 and the outer peripheral surface of the heat exchanging inner tube 3, the heat exchanging outer tube 2 and the heat exchanging inner tube 3 are separated from each other. The thermal conductivity is enhanced. Thermally conductive grease is most suitable as such a lubricating oil.

FIG. 8 is a diagram showing the heat conduction resistance in the heat exchanger of this embodiment. α ₁ is the heat conduction resistance between the atmosphere and the surface of the heat radiation fin 1, α ₂ is the heat conduction resistance between the heat radiation fin 1 and the heat exchange outer tube 2, and α ₃ is the heat exchange outer tube 2 and the heat exchange resistance The heat conduction resistance between the exchange inner pipe 3 and α ₄ is the heat conduction resistance between the inner peripheral surface of the heat exchange inner pipe 3 and the refrigerant (pure water).
β ₁ is a heat conduction resistance in the heat radiation fin 1, β ₂ is a heat conduction resistance in the heat exchange outer tube 2, and β ₃ is a heat conduction resistance in the heat exchange inner tube 3. 1 / K is the sum of the heat conduction resistances α _{1 to} α ₄ and β _{1 to} β ₃ as shown in the following formula (1), and K is the heat transmission coefficient. 1 / K = α ₁ + α ₂ + α ₃ + α ₄ + β ₁ + β ₂ + β ₃ (1) FIG. 10 is a diagram showing the heat conduction resistance in the conventional heat exchanger. α ₅ is the heat conduction resistance between the radiation fin 11 and the stainless steel heat exchange pipe 12, and 1 / k is the heat conduction resistance α ₁ , α ₄ , α ₅ , as shown in the following equation (2).
It is the sum of β ₁ and β ₃ . 1 / k = α ₁ + α ₄ + α ₅ + β ₁ + β ₃ (2) When the individual heat conduction resistances α _{1 to} α ₅ and β _{1 to} β ₃ were measured, the heat in the heat exchanger of this example was measured. Conduction resistance α ₂ , α
It was found that there is a relationship expressed by the following equation (3) between ₃ , β ₂ and the heat conduction resistance α ₅ in the conventional heat exchanger. α ₅ ≈ 2 (α ₂ + α ₃ + β ₂ ) (3) That is, the heat conduction resistance α at the contact portion between the stainless steel heat exchange pipe 12 and the radiation fin 11 in the conventional heat exchanger is It is very large due to the poor adhesion between the exchange pipe 12 and the radiation fin 11, and the total heat conduction resistance 1 /
There is a magnitude relation expressed by the following equation (4) between k and 1 / K. 1 / k-1 / K≈α ₂ + α ₃ + β ₂ (4) That is, the heat transfer resistance of the heat exchanger of this embodiment is about (α ₂ + α ₃ + β ₂ ) more than that of the conventional heat exchanger. It becomes smaller and the heat transfer efficiency is improved. In order to improve the heat conduction efficiency, the heat exchange outer tube 2 that comes into contact with the heat radiation fins 1 is made of copper, which is a soft metal, and is expanded to enhance the adhesion between the heat radiation fins 1 and the heat exchange outer tube 2. Is the main reason. Moreover, it is the inner tube 3 for heat exchange made of stainless steel that comes into contact with the refrigerant (pure water), and the purity of the refrigerant is ensured. Therefore, the heat exchanger of this embodiment can be used for cooling the oscillation part of the laser beam machine which requires cooling with pure water.

In each of the heat exchangers of the conventional and the present embodiments, although a large number of radiating fins are spaced apart from each other, the heat radiating fins 11 of the related art are not in contact with the heat exchanging pipe 12 made of stainless steel. The heat at the site is difficult to transfer to the heat radiation fins 11 due to the low thermal conductivity of stainless steel.
However, in this embodiment, the heat at the non-contact portion of the copper heat exchange outer tube 2 with respect to the heat radiation fins 1 is easily transferred to the heat radiation fins 11 due to the high thermal conductivity of copper, and the copper outer tube is made of stainless steel. The double tube structure in which the inner tube is fitted contributes to the improvement of heat transfer efficiency.

Of course, the present invention is not limited to the above-mentioned embodiment, and for example, a soft metal other than copper can be used as the heat exchange outer tube. Those with high properties are desirable. As the heat exchange inner tube, a material that does not cause a chemical reaction may be appropriately selected according to the kind of the refrigerant.

As a method for expanding the outer pipe for heat exchange, a hydraulic system or a hydraulic system may be used. After expanding the pipe by water pressure or hydraulic pressure to some extent, a spherical or rod-shaped expanding member is inserted to further expand the pipe. A method of doing is also possible.

Further, the expanded heat exchange outer tube may be inserted through the heat exchange outer tube without imparting linearity, or only when the heat exchange outer tube is imparted with linearity, or the heat exchange inner tube. The lubricating oil may be applied only when the is inserted.

[0029]

As described above in detail, in the heat exchanger of the present invention, a large number of heat dissipating fins arranged in parallel are joined to the outer pipe for heat exchange made of a soft metal so as to make contact with the refrigerant. Since the pipe is formed by penetrating and joining the inside of the heat exchange outer pipe, there is an excellent effect that a high heat transfer efficiency can be achieved while ensuring the purity of the refrigerant.

According to the second aspect of the invention, the heat exchange outer tube made of soft metal is penetrated through a large number of heat radiation fins arranged in parallel, and
Pressure is applied to the inner surface of the heat exchanging outer tube to expand it, and lubricating oil is adhered to at least one of the inner surface of the heat exchanging outer tube and the outer surface of the heat exchanging inner tube in contact with the refrigerant for heat exchange. Since the inner tube for heat exchange is fitted and joined in the outer tube for use in manufacturing, it is possible to easily improve the adhesion between the heat radiation fin and the outer tube for heat exchange and to improve the heat conduction efficiency. Produce an effect.

In the third aspect of the present invention, the linearity of the heat exchanging outer tube is increased by inserting the linearity imparting rod into the heat exchanging outer tube after expanding the heat exchanging outer tube and adhering the lubricating oil. The excellent effect of further improving the adhesion between the heat exchange outer tube and the heat exchange inner tube is achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment embodying the present invention.

FIG. 2 is a perspective view of relevant parts showing a state in which a heat exchange outer tube is inserted into a heat radiation fin.

FIG. 3 is an enlarged perspective view for explaining a method of expanding the heat exchange outer tube inserted through the heat radiation fin.

FIG. 4 is an enlarged perspective view for explaining a method for expanding the heat exchange outer tube inserted through the heat radiation fin.

FIG. 5 is an enlarged perspective view for explaining a method of imparting linearity to the expanded outer tube for heat exchange.

FIG. 6 is a perspective view of essential parts showing a state in which a heat exchange inner tube is inserted into a heat exchange outer tube having linearity.

FIG. 7 is an enlarged vertical cross-sectional view of a main part showing a joined state of a heat radiation fin, an outer pipe for heat exchange, and an inner pipe for heat exchange.

FIG. 8 is a diagram for explaining heat conduction resistance.

FIG. 9 is an enlarged vertical cross-sectional view of a main part showing a joined state of a conventional radiation fin and a heat exchange pipe.

FIG. 10 is a diagram for explaining heat conduction resistance.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radiating fin, 2 ... Outer tube for heat exchange, 3 ... Inner tube for heat exchange.

Claims (4)

[Claims] 1. A heat exchange outer pipe made of a soft metal is penetratingly joined to a large number of heat dissipating fins arranged in parallel, and a heat exchange inner pipe which is in contact with a refrigerant is fitted and joined into the heat exchange outer pipe. And a heat exchanger. 2. The heat exchanger according to claim 1, wherein lubricating oil is interposed between the inner peripheral surface of the heat exchanging outer tube and the outer peripheral surface of the heat exchanging inner tube. 3. A heat exchanging outer pipe made of a soft metal is penetrated through a large number of heat dissipating fins arranged in parallel, and a pressure is applied to the inner surface of the heat exchanging outer pipe to expand the heat exchanging outer pipe. Lubricant is attached to at least one of the inner surface of the outer tube and the outer surface of the heat exchanging inner tube that comes into contact with the refrigerant, and after the heat exchanging outer tube is expanded and the lubricating oil is attached, the heat exchanging inner tube is replaced with the heat exchanging inner tube. A method for manufacturing a heat exchanger, characterized in that: 4. A heat exchanging outer pipe made of a soft metal is penetrated through a large number of heat dissipating fins arranged in parallel, and pressure is applied to the inner surface of the heat exchanging outer pipe to expand the heat exchanging outer pipe. Lubricant is adhered to at least one of the inner surface of the outer tube and the outer surface of the pipe for expanding heat, and after the pipe for expanding the pipe for heat exchange and the adhesion of lubricating oil, the linearity imparting rod is inserted into the outer pipe for heat exchange for heat exchange. Heat exchange characterized by increasing the linearity of the outer tube, removing the straightening rod from the heat exchanging outer tube, and then fittingly joining the heat exchanging inner tube that contacts the refrigerant into the heat exchanging outer tube. Manufacturing method.