JPH04332390A - Heat pipe type heat exchanger and manufacture thereof - Google Patents

Abstract

PURPOSE:To contrive the improvement of workability as well as cost down without increasing thermal resistance in the interface between a heat pipe and a heat transfer member. CONSTITUTION:A sealed vessel 5 is contacted closely with heat transfer members 4 by the plastic deformation, generated by the expanding of the sealed vessel 5 due to the vapor pressure of the operating liquid 2 of a predetermined amount, while the sealed vessel 5 is connected to the heat transfer members 4 through fusion of low-melting point connecting metal 3 applied on the surface of the sealed vessel 5 or the heat transfer members 4. In this case, the surface of the heat transfer members 4, having inserting holes 4a with an inner diameter larger than the heat pipe 1 by a predetermined size, or the surface of the heat pipe 1 is coated with the low-melting point connecting metal 3, then, the heat pipe 1 is inserted into the inserting holes 4a and both of them are heated at a predetermined temperature for a predetermined period of time whereby the low-melting point connecting metal 3 is melted, the operating liquid 2 sealed into the heat pipe 1 is heated to provide the heat pipe 1 with the vapor pressure of the operating liquid 2 as well as plastic deformation based on the thermal expansion of the same and contact the outer surface of the heat pipe 1 closely to the inserting holes 4a, then, the heat pipe 1 and the heat transfer members 4 are cooled to connect them.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a heat pipe type heat exchanger comprising a heat transfer member disposed around a heat pipe and a method for manufacturing the same, and particularly relates to a heat pipe type heat exchanger comprising a heat transfer member disposed around a heat pipe and a method for manufacturing the same. The present invention relates to a heat pipe type heat exchanger that improves workability and reduces costs without increasing the size of the heat exchanger, and a method for manufacturing the same.

0002

[Prior Art] Heat pipes have a relatively simple structure in which a working fluid is sealed in a sealed container, and can transfer a large amount of heat with a small temperature difference, so they have been used as heat exchangers in various fields in recent years. has been done. A heat exchanger using such a heat pipe generally has a heat transfer member having radiation fins formed around the outer periphery of the heat pipe.

[0003] In such a heat pipe heat exchanger, the following various methods have been conventionally adopted as means for reducing the thermal resistance value between the heat pipe and the heat transfer member.

[0004] ■ An insertion hole having a diameter slightly smaller than the outer diameter of the heat pipe is formed in the heat transfer member, and the heat pipe is press-fitted into the insertion hole to bring the heat pipe and the heat transfer member into close contact (press-fitting method).

[0005] ■ An insertion hole with a diameter slightly larger than the outer diameter of the sealed container for the heat pipe is formed in the heat transfer member, the container is inserted into this insertion hole, and the container is expanded mechanically using a mandrel or hydraulic pressure. After the container and the heat transfer member are brought into close contact with each other, the container is processed into a heat pipe and the working fluid is sealed therein (mechanical tube expansion method).

[0006] ■ An insertion hole with a diameter slightly larger than the outside diameter of the heat pipe is formed in the heat transfer member, the heat pipe is inserted into this insertion hole, and the gap between the two is filled with highly thermally conductive resin or solder. law).

[0007] ■ An insertion hole with a diameter slightly larger than the outside diameter of the heat pipe is formed in the heat transfer member, and after the heat pipe is inserted into this insertion hole, these are heated to increase the vapor pressure of the working fluid in the closed container. The heat transfer member and the heat pipe are brought into close contact with each other (heating tube expansion method). An example of applying a heat pipe manufactured in this way to the shaft of a motor is disclosed in Japanese Patent Application Laid-open No. 5
It is shown in the publication No. 9-110432.

[0008]

However, the conventional heat pipe type heat exchanger described above has the following disadvantages.

[0009] In the (press-fitting method), the heat pipe press-fitting operation itself is complicated and difficult, and as the number of fins increases, a great deal of effort is required for press-fitting, leading to an increase in cost.

[0010] ■ (Mechanical pipe expansion method) requires a lot of effort to remove residues of lubricant, hydraulic medium, etc. inside the pipe during pipe expansion work, resulting in poor work efficiency and when there are a large number of heat pipes. Heat pipe processing after expansion becomes difficult (
There are many practical difficulties in pipe end processing, hydraulic fluid filling, sealing, etc.).

[0011] In (filling method), the filling operation requires a large cost. In addition, the thermal conductivity of fillers is generally lower than that of heat transfer members and sealed containers for heat pipes.
The filling of the filler increases the interface between the heat pipe and the heat transfer member, which hinders the reduction in thermal resistance.

[0012] ■ (Heating tube expansion method) is excellent in terms of workability, but the coefficient of thermal expansion of the heat transfer member is generally lower than that of a heat pipe. When inserting a heat pipe to heat and expand the pipe, the coefficient of thermal expansion of copper or aluminum (~17x10-6/°C, respectively) inside the material is lower than that of steel (~11x10-6/°C). , ~23x10-6/°C), and even if they are in close contact during heating, the internal copper or aluminum member will shrink more when cooled, and a gap will be formed at the boundary between the two. As a result, thermal resistance increases.

[0013]

[Objective] Therefore, the object of the present invention is to improve workability without increasing the thermal resistance at the interface between the heat pipe and the heat transfer member.
Another object of the present invention is to provide a heat pipe type heat exchanger that can reduce costs and a method for manufacturing the same.

[0014]

[Means for Solving the Problems] The present invention aims to improve workability and reduce costs without increasing the thermal resistance at the interface between the heat pipe and the heat transfer member. A heat pipe heat exchanger in which the sealed container or the heat transfer member is brought into close contact by plastic deformation based on tube expansion due to the vapor pressure of the working fluid, and joined by melting a low melting point joining metal applied to the surface of the sealed container or the heat transfer member. It provides:

[0015] Furthermore, the method for manufacturing a heat pipe type heat exchanger according to the present invention includes processing a heat pipe having a predetermined outer diameter and containing a predetermined amount of working fluid; Processing a heat transfer member having an insertion hole with a predetermined inner diameter larger by the dimension; coating the surface of the heat transfer member or the heat pipe with a low melting point bonding metal such as solder; Insert the heat pipe into the insertion hole; heat both at a predetermined temperature for a predetermined time to melt the low melting point bonding metal, and heat the working fluid sealed in the heat pipe to insert the heat pipe into the heat pipe. is subjected to plastic deformation based on the vapor pressure and thermal expansion of the working fluid, and this plastic deformation brings the outer surface of the heat pipe into close contact with the inner wall of the insertion hole of the heat transfer member; The method includes steps of cooling the member and joining the interface between the heat pipe and the heat transfer member with the low melting point joining metal.

The predetermined temperature is a temperature at which the vapor pressure of the working fluid does not exceed the bursting strength value of the heat pipe at the heating temperature (which is much smaller than the value at room temperature), and the predetermined amount of the working fluid is is equal to or less than the product of the specific volume of steam (vapor volume per unit weight) at the heating temperature and the internal volume of the container, that is, the amount at which no liquid phase of the working fluid exists at the heating temperature.

[0017]

[Operation] As described above, the present invention plastically deforms the heat pipe based on the vapor pressure of a predetermined amount of the working fluid to bring it into close contact with the heat transfer member, and also creates a close interface with the low melting point joining metal that melts during heating. Since the heat pipe and the heat transfer member are joined together, the heat pipe and the heat transfer member can be accurately brought into close contact with each other by an extremely easy operation. That is, since the adhesion state becomes good, the thermal resistance at the interface can be suppressed, and the cost can be reduced by improving the workability.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a heat pipe type heat exchanger and a method for manufacturing the same according to the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1(a) shows the configuration of the heat pipe heat exchanger before final processing is completed. This heat pipe heat exchanger is composed of a heat pipe 1 and a copper fin (heat transfer member) 4 surrounding the heat pipe 1. The surface of the heat pipe 1 is coated with a low melting point bonding metal (such as solder). )3 is coated.

The heat pipe 1 is composed of a cylindrical sealed container 5 and a predetermined amount of working fluid 2 sealed within the sealed container 5. Copper is used as the material for the sealed container, and water is used as the working fluid 2. The amount of hydraulic fluid 2 sealed is such that it will all vaporize at a predetermined temperature T, which will be described later.

[0021] The copper fin 4 has an insertion hole 4a formed in the center thereof into which the heat pipe 1 is inserted. This insertion hole 4a has an inner diameter slightly larger than the outer diameter of the heat pipe 1.

In such a configuration, the heat pipe 1
is inserted into the insertion hole 4a of the copper fin 4, and then the entire heat exchanger is heated to a predetermined temperature T to melt the low melting point bonding metal 3 coated on the surface of the heat pipe 1, and
As shown in (b), the airtight container 5 is closed due to the vapor pressure of the working fluid 2.
is expanded, and the container 5 is brought into close contact with the inner wall of the insertion hole 4a by plastic deformation at that time. Then, by cooling the entire heat pipe heat exchanger and joining the interface between the heat pipe 1 and the copper fin 4, which are in close contact with each other, with a low melting point joining metal,
The entire manufacturing process is completed.

Next, the heating temperature T of the heat pipe heat exchanger and the sealed amount X of the working fluid 2 in the above embodiment will be considered. The heating temperature T is a temperature at which the vapor pressure of the working fluid 2 in the closed container 5 does not exceed the bursting pressure of the closed container 5. for example,
The outer diameter of the copper airtight container 5 is 9.52 mm, and the wall thickness is 0.3 mm.
4 mm, and the effective length is 1000 mm, the heating temperature T is 299°C. As shown in FIG. 2, the vapor pressure P1 (solid line) of water, which is the working fluid 2, with respect to the heating temperature T, and the bursting pressure P of the copper pipe with respect to the heating temperature T.
2 (broken line), the point (304° C.) where both curves P1 and P2 intersect becomes the limit temperature, so the heating temperature T is set to an approximate value lower than this. Further, this temperature is sufficient to melt the low melting point joining metal (solder, etc.) 3.

For the heating temperature T set in this way,
When calculating the sealed amount X of the hydraulic fluid 2, the amount X of the hydraulic fluid 2 is 3.
It will be 0g or less. This is the amount at which no saturated liquid remains when the limit temperature is 304°C, and the internal volume of the closed container 5 (61.
4cm3) is the specific volume of saturated steam (20.3cm3)
It is found by dividing by.

[0025] If the sealed amount Since it is a very small value of 1/571 kgf/cm2 relative to °C, the heating temperature T can be easily adjusted. In addition, the amount of the working fluid 2, which is 2.8 g, corresponds to about 4.6% of the internal volume R (61.4 cm3) of the closed container 2, and is a sufficient amount for use in the bottom heat mode of the heat pipe. .

On the other hand, when the amount X of the hydraulic fluid 2 is set to 3.0 g or more, the amount of change in the outer diameter of the closed container 5 due to the temperature rise is as shown by the curve l (dotted chain line) in FIG. , changes extremely rapidly and the sealed container 5 becomes easy to break.
Practical application will be extremely difficult. This is because when the working fluid 2 in the heat pipe 1 is increased and the heating temperature T is raised near the limit temperature (304°C), the outer diameter of the heat pipe suddenly increases along the straight line L indicating the limit temperature. This is due to the fact that heating can only be done within a much narrower range than the temperature controllable range of a normal heating furnace.

When using the heat pipe heat exchanger manufactured as described above, the heat of the object to be cooled is transferred to the heat pipe 1.
This heat evaporates the working fluid 2 in the heat pipe 1 and transfers heat to the other end (upper part) of the heat pipe 1. The transferred heat is released from the copper fins (heat transfer member) 4, the evaporated gas is condensed, and the condensed working fluid 2 is returned to the heat receiving part (lower part) of the heat pipe 1. By repeating this operation, heat pipe 1
Heat exchange occurs between the object to be cooled and the heat radiation atmosphere (air, cooling medium such as water).

At this time, since the heat pipe 1 and the copper fins 4 are in good contact with each other, there is almost no heat loss at the boundary between the two. The degree of adhesion increases as the temperature difference from the temperature during processing increases.

[0029]

Effects of the Invention As explained above, according to the heat pipe type heat exchanger and the manufacturing method of the present invention, the airtight container is expanded by the vapor pressure inside the airtight container of the heat pipe, and the airtight container is expanded by the plastic deformation at that time. Since the heat pipe and the heat transfer member are brought into close contact with each other, and the two are joined by melting a low melting point bonding metal such as solder applied to the surface of the airtight container or the heat transfer member, the thermal resistance at the interface between the heat pipe and the heat transfer member is reduced. It is possible to improve workability and reduce costs without increasing.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is a graph for explaining the effect of the embodiment.

[Explanation of symbols]

1 Heat pipe 2 Hydraulic fluid 3. Low melting point joining metal 4 Copper fins 4a Insertion hole 5 Sealed container

Claims (3)

[Claims] 1. A heat pipe having a predetermined amount of working fluid sealed in an airtight container, a heat transfer member surrounding the heat pipe with some margin, and a heat transfer member provided on the surface of the airtight container or the heat transfer member. The closed container and the heat transfer member are brought into close contact with each other by plastic deformation based on the tube expansion of the closed container due to the vapor pressure of the working fluid, and the low melting point joining metal is melted. A heat pipe type heat exchanger characterized by being joined by. 2. A heat transfer method in which a heat pipe having a predetermined outer diameter and containing a predetermined amount of working fluid is processed and has an insertion hole having a predetermined inner diameter that is larger than the predetermined outer diameter by a predetermined dimension. The member is processed, the surface of the heat transfer member or the heat pipe is coated with a low melting point bonding metal such as solder, the heat pipe is inserted into the insertion hole of the heat transfer member, and both are heated to a predetermined temperature. The low melting point joining metal is melted by heating for a predetermined period of time, and the working fluid is heated to give the heat pipe plastic deformation based on the vapor pressure and thermal expansion of the working fluid. The outer surface of the heat pipe is brought into close contact with the inner wall of the insertion hole of the heat transfer member, the heat pipe and the heat transfer member that are in close contact are cooled, and the interface between the heat pipe and the heat transfer member is joined. A manufacturing method for a heat pipe type heat exchanger. 3. The predetermined temperature is a temperature at which the working fluid does not have a vapor pressure higher than the bursting strength value of the heat pipe, and the amount of the working fluid sealed is such that no liquid phase remains at the predetermined temperature. 3. The method for manufacturing a heat pipe type heat exchanger according to claim 2, wherein