US20120261093A1

US20120261093A1 - Heat pipe

Info

Publication number: US20120261093A1
Application number: US13/295,593
Authority: US
Inventors: Yukio Miyachi; Hiroshi Osada; Norifumi Furuta
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2011-04-12
Filing date: 2011-11-14
Publication date: 2012-10-18
Also published as: JP2012220141A

Abstract

A heat pipe comprises a housing that has a heating section that is made of metal and is contacted by a heating element, a cooling section that is made of metal and is cooled by a cooling element, and a plurality of refrigerant flow channels formed inside the housing from the heating section to the cooling section; refrigerant that is enclosed inside the plurality of refrigerant flow channels; and heat-insulating layers that are disposed between the plurality of refrigerant flow channels located at least at the heating section in the housing.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2011-88486 filed on Apr. 12, 2011, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates to a heat pipe.
2. Related Art
Conventionally, flat plate-like heat pipes having plural pores inside, such as those described in Japanese Patent No. 3,438,087 and Japanese Patent Application Laid-Open (JP-A) No. 2006-52942, have been known. In these heat pipes, heat exchange with a heating element is performed by refrigerant flowing through the plural pores into a heating section side and refrigerant returning from the heating section to a cooling section.

SUMMARY

However, in the above-described heat pipes, although the refrigerant flowing into the heating section side should exchange heat only with the heating element, it also exchanges heat with the refrigerant returning through the adjacent pores from the heating section to the cooling section, and so the cooling efficiency of the heating element drops.
The present invention has been made in view of the above-described situation and provides a heat pipe that can improve the cooling efficiency of the heating element.
A heat pipe of a first aspect of the present invention includes: a housing that has a heating section that is made of metal and is contacted by a heating element, a cooling section that is made of metal and is cooled by a cooling element, and plural refrigerant flow channels formed inside the housing from the heating section to the cooling section; refrigerant that is enclosed inside the plural refrigerant flow channels; and heat-insulating layers that are disposed between the plural refrigerant flow channels at least in the heating section in the housing.
According to the above heat pipe, the heat-insulating layers are disposed between the plural refrigerant flow channels at least in the heating section in the housing. Consequently, the refrigerant flowing into the heating section side can be suppressed from exchanging heat with the refrigerant returning through the adjacent refrigerant flow channels from the heating section to the cooling section. Because of this, the heat exchange efficiency between the refrigerant flowing into the heating section side and the heating element can be improved, so the cooling efficiency of the heating element can be improved.
A heat pipe of a second aspect of the present invention is the heat pipe of the first aspect, wherein in the housing, groove portions are formed in partition walls between the plural refrigerant flow channels, and the heat-insulating layers are formed by a heat-insulating material filling the groove portions.
According to this heat pipe, by forming the groove portions in the housing and filling the groove portions with the heat-insulating material, the heat-insulating layers can be easily formed inside the housing.
A heat pipe of a third aspect of the present invention is the heat pipe of the first aspect, wherein in the housing, plural hole portions are formed from the heating section to the cooling section, any hole portions of the plural hole portions are made to serve as the plural refrigerant flow channels, and the heat-insulating layers are formed as a result of the insides of remaining hole portions of the plural hole portions being filled with a heat-insulating material.
According to this heat pipe, the housing can be easily manufactured because it suffices to form the plural hole portions in the housing without having to distinguish between those for the refrigerant flow channels and those for the heat-insulating layers.
A heat pipe of a fourth aspect of the present invention is the heat pipe of the first aspect, wherein the housing has a main body portion that has a plate-like base portion and plural fins that extend in a normal direction from the base portion and are formed in parallel to each other and a cover portion that opposes the base portion and is fixed to distal ends of the plural fins, any groove portions of groove portions between the plural fins are made to serve as the plural refrigerant flow channels, and the heat-insulating layers are formed as a result of the insides of remaining plural groove portions of the plural groove portions being filled with a heat-insulating material.
According to this heat pipe, the housing can be easily manufactured because it suffices to form the main body portion in the form of a heat sink having the plural fins.
A heat pipe of a fifth aspect of the present invention is the heat pipe of the first aspect, wherein the housing has a heat-insulating section between the heating section and the cooling section.
According to this heat pipe, the cooling efficiency of the heating element can be improved more because the heating section and the cooling section can be thermally insulated by the heat-insulating section.
A heat pipe of a sixth aspect of the present invention is the heat pipe of the fifth aspect, wherein both lengthwise direction sides of the plural refrigerant flow channels open to an end face of the housing on the heating section side and to an end face of the housing on the cooling section side, and the heat pipe further includes a pair of closing portions that are disposed on the end face of the housing on the heating section side and the end face of the housing on the cooling section side and that close openings on both lengthwise direction sides of the plural refrigerant flow channels.
According to this heat pipe, the manufacture of the heat pipe can be made easy because it is not necessary to swage both end portions of the housing in order to close the openings on both lengthwise direction sides of the plural refrigerant flow channels.
A heat pipe of a seventh aspect of the present invention is the heat pipe of the sixth aspect, wherein the pair of closing portions, the heat-insulating section, and the heat-insulating layers are formed integrally from a resin.
According to this heat pipe, costs can be reduced because the pair of closing portions, the heat-insulating section, and the heat-insulating layers are formed integrally from a resin.
As described in detail above, according to the present invention, the cooling efficiency of the heating element can be improved because the heat exchange efficiency between the refrigerant flowing into the heating section side and the heating element can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a side view of a heat pipe pertaining to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a cross-sectional view showing a first modification of the heat pipe pertaining to the embodiment of the present invention;

FIG. 5 is a cross-sectional view showing a second modification of the heat pipe pertaining to the embodiment of the present invention;

FIG. 6 is a cross-sectional view showing a third modification of the heat pipe pertaining to the embodiment of the present invention; and

FIG. 7 is a cross-sectional view showing a fourth modification of the heat pipe pertaining to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a heat pipe 10 pertaining to the embodiment of the present invention has a flat board-like housing 12. The entire housing 12 is formed by metal, such as an aluminum alloy or copper, whose heat conductivity is high.
In the housing 12, one end side is made to serve as a heating section 16 that is contacted by a heating element 14 that is an IGBT or MOS semiconductor device, for example, and the other end side is made to serve as a cooling section 20 that is cooled by a cooling element 18 such as a water-cooled block, a heat sink, or a gas, for example. In a case where the heating element 14 is a semiconductor device, an insulating substrate on which an electrical circuit is disposed may also be placed between the heating element 14 and the heating section 16.
Inside the housing 12, as shown in FIG. 2, plural refrigerant flow channels 22A to 22F are formed in parallel from the heating section 16 to the cooling section 20. Further, at the heating section 16 side, the end portions of the refrigerant flow channel 22A and the refrigerant flow channel 22B, the end portions of the refrigerant flow channel 22C and the refrigerant flow channel 22D, and the end portions of the refrigerant flow channel 22E and the refrigerant flow channel 22F are respectively connected by connecting flow channels 24A to 24C that extend in the direction in which the plural refrigerant flow channels 22A to 22F are lined up.
At the cooling section 20 side, the end portions of the refrigerant flow channel 22B and the refrigerant flow channel 22C and the end portions of the refrigerant flow channel 22D and the refrigerant flow channel 22E are likewise respectively interconnected by connecting flow channels 24D and 24E that extend in the direction in which the plural refrigerant flow channels 22A to 22F are lined up. An open circuit-like inside flow channel 26 is thus formed inside the housing 12 as a result of the plural refrigerant flow channels 22A to 22F being connected by the plural connecting flow channels 24A to 24E in this manner.
Within the inside flow channel 26, an organic liquid such as water, Freon, or butane is enclosed as refrigerant 28. In the heat pipe 10, the heat of the heating element 14 moves via the refrigerant 28 from the heating section 16 to the cooling section 20. That is, the heat pipe 10 is configured as a self-excited heat pipe.
Further, as shown in FIG. 2 and FIG. 3, in the housing 12, groove portions 32 are formed in partition walls 30A to 30E provided in the plural refrigerant flow channels 22A to 22F. The groove portions 32 are formed from the heating section 16 through the cooling section 20.
Additionally, the groove portions 32 are filled with a heat-insulating material, whereby heat-insulating layers 34 are formed in the plural refrigerant flow channels 22A to 22F. As the heat-insulating material forming the heat-insulating layers 34, a gas such as air, or a resin, ceramic, or metal respective thermal conductivities are low, or a material obtained by making these materials into a porous body by foaming or the like, is used. Further, the heat-insulating layers 34 may also be vacuum layers.
The heat pipe 10 is manufactured in the following way, for example. That is, first, a porous flat tube having plural hole portions that become the basis of the plural refrigerant flow channels 22A to 22F is created by extrusion. Then, the groove portions 32 are formed in the partition walls 30A to 30E by cutting or the like, for example. Next, the groove portions 32 are filled with the heat-insulating material that becomes the basis of the heat-insulating layers 34, and thereafter these are heated and fired.
Then, the end portions of the partition walls 30A, 30C, and 30E on the heating section 16 side are cut to form interstices that become the basis of the connecting flow channels 24A to 24C, and the end portions of the partition walls 30B and 30D on the cooling section 20 side are cut to form interstices that become the basis of the connecting flow channels 24D and 24E.
Next, one of the end portions of the housing 12 on the heating section 16 side and the cooling section 20 side is swaged by spot welding, and the refrigerant 28 is put into the plural refrigerant flow channels 22A to 22F. Then, the other of the end portions of the housing 12 on the heating section 16 side and the cooling section 20 side is swaged by spot welding to form the open circuit-like inside flow channel 26 within the housing 12. The heat pipe 10 is manufactured in the above way.
Next, the action and effects of the embodiment of the present invention will be described.
According to this heat pipe 10, the heat-insulating layers 34 are disposed between the plural refrigerant flow channels 22A to 22F. Consequently, the refrigerant 28 flowing into the heating section 16 from the cooling section 20 can be suppressed from exchanging heat with the refrigerant returning through the adjacent refrigerant flow channels from the heating section 16 to the cooling section 20. Because of this, the heat exchange efficiency between the refrigerant flowing into the heating section 16 and the heating element 14 can be improved, so the cooling efficiency of the heating element 14 can be improved.
Further, by forming the plural groove portions 32 by additional work in the housing 12 and filling the groove portions 32 with the heat-insulating material, the plural heat-insulating layers 34 can be easily formed inside the housing 12.
Next, modifications of the embodiment of the present invention will be described.
In the above-described embodiment, the heat-insulating layers 34 are formed from the heating section 16 to the cooling section 20, but, for example, as shown in FIG. 4, the heat-insulating layers 14 may also be formed just in the heating section 16.
Further, for example, as shown in FIG. 4, in a case where narrow partition walls 30A, 30C, and 30E and wide partition walls 30B and 30D are alternately formed between the plural refrigerant flow channels 22A to 22F, the heat-insulating layers 34 may also be disposed just in the narrow partition walls 30A, 30C, and 30E.
Further, in the above-described embodiment, the inside flow channel 26 is provided in the form of an open circuit, but, for example, as shown in FIG. 4, the inside flow channel 26 may also be provided in the form of a closed circuit as a result of a connecting flow channel 24F that connects the end portions of the refrigerant flow channel 22A and the refrigerant flow channel 22F being formed only on the cooling section 20 side.
Further, as shown in FIG. 5, in the housing 12, plural hole portions 36 may also be formed from the heating section 16 to the cooling section 20 (see FIG. 1 for both), in such a manner that hole portions 36 provided on both sides and lined up every other one from these hole portions 36 are made to serve as the plural refrigerant flow channels 22A to 22F. Additionally, the heat-insulating layers 34 may also be formed between the plural refrigerant flow channels 22A to 22F as a result of remaining plural hole portions 36 being filled with a heat-insulating material such as a polyamide resin, for example.
According to this modification, the housing 12 can be manufactured more easily by extrusion molding or the like because it suffices to form the plural hole portions 36 in the housing 12 without having to distinguish between those for the refrigerant flow channels and those for the heat-insulating layers.
Further, the housing 12 may also be configured as shown in FIG. 6. That is, in the modification shown in FIG. 6, the housing 12 is divided into a main body portion 38 and a cover portion 40.
The main body portion 38 has a plate-like base portion 41 and plural fins 44 that extend in a normal direction from the base portion 41 and are formed in parallel to each other. The plural fins 44 are formed from the heating section 16 to the cooling section 20 (see FIG. 1 for both). The cover portion 40 is formed in a plate-like shape similar to the base portion 41, opposes the base portion 41, and is fixed to distal ends of the plural fins 44. Further, wall portions 45 that extend toward the base portion 41 side are formed on both sides of the cover portion 40.
Additionally, any plural groove portions 42A to 42F of groove portions between the plural fins 44 are made to serve as the refrigerant flow channels 22A to 22F. Further, the heat-insulating layers 34 are formed as a result of the insides of remaining plural groove portions 46A to 46E of the groove portions between the plural fins 44 being filled with a heat-insulating material.
According to this modification, the housing 12 can be easily manufactured because it suffices to form the main body portion 38 in the form of a heat sink having the plural fins 44.
The positions of the first groove portions 42A to 42F and the second groove portions 46A to 46E may also be opposite.
Further, the housing 12 may also be configured such as shown in FIG. 7. That is, in the modification shown in FIG. 7, the housing 12 is configured to have, in addition to the heating section 16 and the cooling section 20 that are formed in blocks, a heat-insulating section 48 that is likewise formed in a block. The heating section 16 and the cooling section 20 are made of metal, and the heat-insulating section 48 is made from a resin. Further, the heat-insulating section 48 is placed between the heating section 16 and the cooling section 20.
Inside the housing 12 that is configured to have the heating section 16, the cooling section 20, and the heat-insulating section 48, the plural refrigerant flow channels 22A to 22C are formed from the heating section 16 through the heat-insulating section 48 to the cooling section 20. Both lengthwise direction sides of the plural refrigerant flow channels 22A to 22C open to an end face 16A of the heating section 16 and to an end face 20A of the cooling section 20. The end face 16A locates at the opposite side of the heat-insulating section 48 side (an end face of the housing 12 on the heating section 16 side) and the end face 20A locates at the opposite side of the heat-insulating section 48 side (an end face of the housing 12 on the cooling section 20 side).
Further, in the heating section 16, hole portions 52 are formed in partition walls 50 between the plural refrigerant flow channels 22A to 22C. Both lengthwise direction sides of the hole portions 52 open to the end face 16A of the heating section 16 and to an end face 16B of the heating section 16 at the heat-insulating section 48 side. Heat-insulating layers 54 are formed as a result of the insides of the hole portions 52 being filled with a heat-insulating material.
In the cooling section 20, hole portions 58 are formed in partition walls 56 between the plural refrigerant flow channels 22A to 22C. Both lengthwise direction sides of the hole portions 58 open to the end face 20A of the cooling section 20 and to an end face 20B of the cooling section 20 at the heat-insulating section 48 side. Heat-insulating layers 60 are formed as a result of the insides of the hole portions 58 being filled with a heat-insulating material.
Moreover, in this modification, a pair of closing portions 62 made from a resin are added. The pair of closing portions 62 are disposed on the end face 16A of the heating section 16 and on the end face 20A of the cooling section 20 and close openings on both lengthwise direction sides of the plural refrigerant flow channels 22A to 22C as well as openings on one lengthwise direction side of each of the plural hole portions 52 and 58.
According to this modification, the cooling efficiency of the heating element 14 can be improved more because the heating section 16 and the cooling section 20 can be thermally insulated by the heat-insulating section 48.
Further, the manufacture of the heat pipe 10 can be made easy because it is not necessary to swage both end portions of the housing 12 in order to close the openings on both lengthwise direction sides of the plural refrigerant flow channels 22A to 22C.
The heat-insulating section 48, the heat-insulating layers 54 and 60, and the pair of closing portions 62 may also be formed integrally by a resin. Doing so can reduce costs.
Of the plural modified embodiments described above, the embodiments that can be combined may of course be appropriately selected and implemented.
An embodiment of the present invention has been described above, but the present invention is not limited to the above description and, in addition to the above description, can of course also be variously modified and implemented in a range not departing from the gist thereof.

Claims

1. A heat pipe comprising:

a housing that has

a heating section that is made of metal and is contacted by a heating element,

a cooling section that is made of metal and is cooled by a cooling element, and a plurality of refrigerant flow channels formed inside the housing from the heating section to the cooling section;

refrigerant that is enclosed inside the plurality of refrigerant flow channels; and

heat-insulating layers that are disposed between the plurality refrigerant flow channels located at least at the heating section in the housing.

2. The heat pipe according to claim I, wherein

in the housing, groove portions are formed in partition walls between the plurality of refrigerant flow channels, and

the heat-insulating layers are formed by a heat-insulating material filling the groove portions.

3. The heat pipe according to claim 1, wherein

in the housing, a plurality of hole portions are formed from the heating section to the cooling section,

any hole portions of the plurality of hole portions are made to serve as the plurality of refrigerant flow channels, and

the heat-insulating layers are formed as a result of the insides of remaining hole portions of the plurality of hole portions being filled with a heat-insulating material.

4. The heat pipe according to claim 1, wherein

the housing has

a main body portion that has a plate-like base portion and a plurality of fins that extend in a normal direction from the base portion and are formed in parallel to each other and

a cover portion that opposes the base portion and is fixed to distal ends of the plurality of fins,

any groove portions of groove portions between the plurality of fins are made to serve as the plurality of refrigerant flow channels, and

the heat-insulating layers are formed as a result of the insides of remaining groove portions of the groove portions between the plurality of fins being filled with a heat-insulating material.

5. The heat pipe according to claim 1, wherein the housing further has a heat-insulating section between the heating section and the cooling section.

6. The heat pipe according to claim 5, wherein

both lengthwise direction sides of the plurality of refrigerant flow channels open to an end face of the housing on the heating section side and to an end face of the housing on the cooling section side, and

the heat pipe further comprises a pair of closing portions that are disposed on the end face of the housing on the heating section side and the end face of the housing on the cooling section side and that close openings on both lengthwise direction sides of the plurality of refrigerant flow channels.

7. The heat pipe according to claim 6, wherein the pair of closing portions, the heat-insulating section, and the heat-insulating layers are formed integrally from a resin.