Heat pipe

Abstract

A heat pipe includes a tube, a capillary structure, and a working fluid. The tube seals a space and has an evaporating portion, a condensing portion, and a heat insulation portion connected between the evaporating portion and the condensing portion. An opening area defined by one of the condensing portion and the evaporating portion is larger than an opening area defined by the heat insulation portion. The capillary structure is disposed on an inner surface of the tube. The working fluid is disposed in the tube.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 98113090, filed on Apr. 17, 2009. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to a thermal conduction device, and more particularly, to a heat pipe.

2. Description of Related Art

In recent years, since the technology being greatly improved, the operation efficiency of the electrical elements becomes higher, and the heating power of the electrical elements is growing. Heat pipe is widely used in the heat dissipation area because the heat pipe has high thermal conduction efficiency, small size, no movable element, and simple structure, and the heat pipe may conduct plenty of heat when the heat pipe is kept about the same temperature.

Referring to FIG. 1, a conventional heat pipe 100 includes a tube 110, a capillary structure 120, and a working fluid 130 sealed in the tube 110. The heat pipe 100 is pumped into an evacuate pipe, then the proper working fluid 130 is injected into the pipe, the capillary structure 120 of the heat pipe 100 is full of working fluid 130, and then the heat pipe 100 is sealed. One end of the heat pipe 100 is an evaporating portion 100a, the other end of the heat pipe 100 is a condensing portion 100b, and a heat insulation portion may be disposed between the evaporating portion 100a and the condensing portion 100b. The working fluid 130 evaporates and vaporizes into steam 140 when the evaporating portion 100a of the heat pipe 100 is heated, the steam 140 flows to the condensing portion 100b for the differential pressure, so that the steam 140 is condensed into working fluid 130 at the condensing portion 100b, and then the working fluid 130 flows back to the evaporating portion 100a through the capillary structure 120 by the capillary forces. As the circle described above, heat A may be continually transferred from the evaporating portion 100a of the heat pipe 100 to the condensing portion 100b of the heat pipe 100 to be dissipated.

The conventional heat pipe generally has a same tube diameter. The heat pipe absorbs heat through the area of the evaporating portion and dissipates heat through the area of the condensing portion, so that, when the heat pipe is applied in a electrical element having high heating power, the length of the heat pipe is longer or the number of the heat pipes is increased, thus the cost is increased and the efficiency of the heat pipe decreases when the length of the heat pipe become longer. Besides, if enlarging the area of the evaporating portion and the area of the condensing portion by increasing the tube diameter of the heat pipe, the heat pipe may have a relatively big bent radius, and the big bent radius makes the space design inconvenient.

For example, Taiwan patents no. M254578, M279909, and 407445 discloses a heat pipe having same tube diameter, the heat dissipation efficiency of the heat pipe is limited and the heat pipe increases the area of the evaporating portion and the area of the condensing portion by extending the length or increasing the number of the heat pipe.

SUMMARY OF THE INVENTION

Accordingly, the invention provides a heat pipe having high efficiency of heat dissipation and small size.

Other advantages of the present invention should be further indicated by the disclosures of the present invention, and omitted herein for simplicity.

To achieve at least one of the above-mentioned advantages, an embodiment of the invention provides a heat pipe including a tube, a capillary structure, and a working fluid. The tube seals a space and includes an evaporating portion, a condensing portion, and a heat insulation portion connected between the evaporating portion and the condensing portion, wherein an opening area defined by one of the condensing portion and the evaporating portion is larger than an opening area defined by the heat insulation portion. The capillary structure is disposed on an inner surface of the tube, and the working fluid is disposed in the tube.

In one embodiment of the invention, the tube is made of a thermal conductive material, for example, metal.

In one embodiment of the invention, the tube is flat shape, and further includes a spacer disposed in the tube for supporting two opposite sides of the tube.

In one embodiment of the invention, the capillary is selected from the group consisting of a sintered powder, a metal mesh capillary structure, and a groove type capillary structure. The sintered powder is disposed on the evaporating portion, and the metal mesh capillary structure and the groove type capillary structure are disposed on the condensing portion. In the embodiment, the opening area defined by the condensing portion is larger than the opening area defined by the heat insulation portion, the opening area defined by the evaporating portion is equal to the opening area defined by the heat insulation portion, and the cross-sectional area of the capillary structure located in the area where the heat insulation portion is perpendicular to the extending direction of the heat pipe is larger than or equal to the cross-sectional area of the capillary structure located in the area where the condensing portion is perpendicular to the extending direction of the heat pipe.

In one embodiment of the invention, the opening area defined by the condensing portion is larger than the opening area defined by the heat insulation portion, the opening area defined by the evaporating portion is larger than the opening area defined by the heat insulation portion, and the cross-sectional area of the capillary structure located in the area where the heat insulation portion is perpendicular to the extending direction of the heat pipe is larger than or equal to the cross-sectional area of the capillary structure located in the area where the condensing portion is perpendicular to the extending direction of the heat pipe.

In one embodiment of the invention, the heat pipe is line shape, and the evaporating portion and the condensing portion are located at two sides of the heat insulation portion respectively.

In one embodiment of the invention, the heat pipe is U shape, the evaporating portion is located at the middle of the heat pipe, the condensing portion is located at two sides of the heat pipe, and the heat insulation portion is located at two curved sections of the heat pipe and connects to the evaporating portion and the condensing portion.

In summary, the embodiment or the embodiments of the invention may have at least one of the following advantages. The heat pipe of the embodiments has different cross-sectional areas or different tube diameters, the cross-sectional area or the tube diameter of the condensing portion (and the evaporating portion) is larger than the cross-sectional area or the tube diameter of the heat insulation portion, so that, when the heat pipe have the same length and the same cross-sectional area of the heat insulation portion, the heat pipe of the embodiment of the invention has a larger condensing area and a larger heat-contacting area than a conventional heat pipe having the same tube diameter, in other words, the heat dissipating efficiency of the heat pipe of the embodiment of the invention is higher, and the heat pipe may take more heat away, as a result, the limited of the heat dissipating efficiency of the conventional heat pipe is solved. Moreover, different capillary structures applied in the condensing portion and the evaporating portion may make the wording fluid flow smoothly to increase the heat dissipation efficiency.

Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is an axial-sectional diagram of a conventional heat pipe.

FIG. 2A is an axial-sectional diagram of a heat pipe according to a first embodiment of the invention.

FIG. 2B is a cross-sectional diagram of a evaporating portion of the heat pipe of FIG. 2A.

FIG. 2C is a cross-sectional diagram of a condensing portion of the heat pipe of FIG. 2A.

FIG. 3 is an axial-sectional diagram of a heat pipe according to a second embodiment of the invention.

FIG. 4 is an axial-sectional diagram of a heat pipe according to a third embodiment of the invention.

FIG. 5 is a cross-sectional diagram of a heat pipe according to a fourth embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that

“A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

The First Embodiment

Referring to FIGS. 2A to 2C, a heat pipe 200 of the embodiment is line shape and includes a tube 210, a capillary structure 220, and a working fluid 230. The tube 210 seals a space and includes an evaporating portion 200a, a condensing portion 200b, and a heat insulation portion 200c connected between the evaporating portion 200a and the condensing portion 200b, wherein the tube 200 is made of a thermal conductive material, for example, metal. The evaporating portion 200a and the condensing portion 200b are disposed at two ends of the heat pipe 200, and in the embodiment, an opening area defined by the condensing portion 200b is larger than an opening area defined by the heat insulation 200c, an opening area defined by the evaporating portion 200a is equal to the opening area defined by the heat insulation portion 200c. For example, the tube diameter of the condensing portion 200b is larger than the tube diameter of the heat insulation portion 200c, and the tube diameter of the evaporating portion 200a is equal to the tube diameter of the heat insulation 200c. The capillary structure 220 is disposed on an inner surface of the tube 210 and the working fluid 230 is disposed in the tube 210.

In the embodiment, the capillary structure 220 is selected from the group consisting of a sintered powder 220a, a groove type capillary structure 220b, and a metal mesh capillary structure 220c. Specifically, the sintered powders 220a may increase strength of the capillary structures 220 and form thin and tiny capillary holes to improve the capillary effect to insure the working fluid 230 may be absorbed quickly to the evaporating portion 200a. So that the sintered powders 200a may be disposed on the evaporating portion 200a in the inner of the tube 210 (as shown in FIG. 2B). Besides, the groove type capillary structure 220b has a larger capillary diameter relative to the sintered powder 220a and generates a small flow resistance to the working fluid 230, and the metal mesh capillary structure 220c may enhance the anti-gravity of the heat pipe 200, so that the metal mesh capillary structure 220c and the groove type capillary structure 220b may be disposed on the condensing portion 200b in the inner surface of the tube 210 (as shown in FIG. 2C) to drive the working fluid 230 back to the evaporating portion 200a from the condensing portion 200b. Moreover, the cross-sectional area of the capillary structure 220 located in the area where the heat insulation portion 200c is perpendicular to the extending direction of the heat pipe 200 is larger than or equal to the cross-sectional area of the capillary structure 220 located in the area where the condensing portion 200b is perpendicular to the extending direction of the heat pipe 200. The quantity of capillary structures 220 padded in the thin part is more than or equal to the quantity of the capillary structures 220 padded in the thicker part to make sure the transmission speed of the working fluid 230 be the same in capillary structures 220 of different diameters.

Since the heat pipe 200 of the embodiment has different opening areas or different tube diameters, the opening area of the condensing portion 200b is larger than the opening areas of the heat insulation portion 200c and the evaporating portion 200a, and when the heat pipe 200 has the same length and the same opening area of the heat insulation portion 200c, the opening area of the condensing portion 200b according to the heat pipe 200 of the embodiment is larger than the opening area of the condensing portion 100a of the conventional heat pipe 100 having the same tube diameter, so that the heat pipe 200 of the embodiment of the invention has a larger condensing area than the conventional heat pipe 100 having the same tube diameter, in other words, the heat pipe 200 of the embodiment has high heat dissipation efficiency to solve the heat dissipation problem of the conventional heat pipe 100. Different capillary structures 220 are applied in the condensing portion 200a and the evaporating portion 200b to make the working fluid 230 flow smoothly, so as to improve the heat dissipation efficiency. In other embodiments, the opening area defined by the evaporating portion 200a may be larger than the opening area defined by the heat insulation portion 200c, and the opening area defined by the condensing portion 200b may be equal to the opening area defined by the heat insulation portion 200c. So that the heat pipe 200 has a larger heat contacting area than the conventional heat pipe 100, and the heat dissipating efficiency is improved.

Some of the manufacture methods for the heat pipe of the embodiment may provides as following:

Method one: provide two hollow pipes having different opening areas or different tube diameters to be the tube of the heat pipe, the openings of the hollow pipe may be a standard circle, a square, an ellipse, or a triangle, and the hollow pipe may be a line shape or a bent pipe of other shapes. Connect the two hollow pipes and seal one end of the hollow pipe having a smaller opening area. The two hollow pipes are connected by temperature diffusivity in a high pressure. Then, pad the capillary structure, sintered powders for example, and then sinter the capillary structure. Empty the connected hollow pipes and dispose the working fluid in the pipe. At last, seal the end of the hollow pipe having a larger opening area, and a heat pipe having different opening areas is formed.

Method two: provide a hollow pipe to be the tube of the heat pipe, seal one end of the hollow pipe, and put the hollow pipe in an expansion mould. The mould includes a forming area having a groove. Inject a high pressure fluid into the hollow pipe, and the part of the hollow pipe corresponding to the forming area expands toward the groove by the pressure of the high pressure fluid. Get the hollow pipe out of the mould, and a hollow pipe having different opening area is formed, then the process of padding the capillary structure into the pipe is the same as method one.

Method three: provide a hollow pipe to be the tube of the heat pipe, seal one end of the hollow pipe, and put a steel rod having a larger cross-sectional area into the hollow pipe. The hollow pipe may have a plastic distortion by the steel rod enforced pressing to the hollow pipe, and a hollow pipe having different opening area is formed, then the process of padding the capillary structure into the pipe is the same as method one.

The Second Embodiment

Referring to FIG. 3, a heat pipe 300 is similar to the heat pipe 200 in FIG. 2A, and the differences are described as following.

Opening areas defined by a evaporating portion 300a and a condensing portion 300b of the heat pipe 300 are larger than an opening area defined by a heat insulation portion 300c of the heat pipe 300, and the opening areas defined by the evaporating portion 300a and the condensing portion 300b of the heat pipe 300 may be the same or be different. Since the heat pipe 300 has the same length and the heat insulation portion 300c has the same opening area, the opening areas defined by the evaporating portion 300a and the condensing portion 300b of the heat pipe 300 of the embodiment are larger than the opening areas of the evaporating portion 100a and the condensing portion 100b of the heat pipe 100 having the same tube diameter, so that the heat pipe 300 of the embodiment has a larger condensing area and a larger heat contacting area than the conventional heat pipe 100 does, thus the heat pipe 300 has a high heat dissipation efficiency and heat conducting speed.

The Third Embodiment

Referring to FIG. 4, a heat pipe 400 is similar to the heat pipe 200 in FIG. 2A, and the differences are described as following.

The heat pipe 400 is U shape, wherein a evaporating portion 400a is located at the middle of the heat pipe 400, a condensing portion 400b is located at two ends of the heat pipe 400, and a heat insulation portion 400c is located at two curved sections of the heat pipe 400 and connected between the evaporating portion 400a and the condensing portion 400b. In the embodiment, since opening areas defined by the evaporating portion 400a and the condensing portion 400b are larger than an opening area defined by the heat insulation portion 400c, and if the opening area or the tube diameter of the conventional heat pipe 100 is equal to the opening area or the tube diameter of the heat insulation portion 400c of the heat pipe 400, the heat pipe 400 of the embodiment has a larger condensing area and a larger heat-contacting area; in the other side, if the opening area or the tube diameter of the conventional heat pipe 100 is equal to the opening area or the tube diameter of the evaporating portion 400a or the condensing portion 400b of the heat pipe 400, the heat pipe 400 of the embodiment has a small bent radius for the heat insulation portion 400c of the heat pipe 400 having a small opening area or tube diameter, so that, the capillary structure being broken due to the big bent radius is avoided, and the transmission speed may not be influenced; besides, the heat pipe 400 has a small volume for the small bent radius.

The Fourth Embodiment

Referring to FIG. 5, a heat pipe 500 is similar to the heat pipe 200 in FIG. 2B, and the differences are described as following.

The heat pipe 500 is rectangle shape, in other words, the rectangle shape heat pipe 500 is formed by beating the heat pipe 200 flat, the advantage of the heat pipe 500 is that the inner floor area ratio of the heat pipe 500 is larger than the inner floor area ratio of the heat pipe 200, so that the heat pipe 500 has high heat dissipating efficiency. Besides, since the tube of the heat pipe 500 is thin, a spacer 501 may be disposed inside of the heat pipe 500 for supporting two opposite sides of the tube to enhance the strength of the heat pipe 500.

In summary, the embodiment or the embodiments of the invention may have at least one of the following advantages. Since the heat pipe has different opening areas or tube diameters, the tube diameter or opening area defined by the condensing portion (and the evaporating portion) is larger than tube diameter or the opening area defined by the heat insulation portion, and if the heat pipes have the same length and the same opening area of the heat insulation portion, the heat pipe of the embodiment has a larger condensing area and heat-contacting area than the conventional heat pipe; in the other side, if the tube diameter or the opening area of the conventional heat pipe is equal to the diameter or the opening area of the evaporating portion or the condensing portion of the heat pipe, the heat pipe of the embodiment has a small bent radius for the opening area or the diameter of the heat insulation portion is small, thus the volume of the heat pipe is reduced.

The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.

Claims

1. A heat pipe, comprising

a tube, sealing a space and comprising an evaporating portion, a condensing portion, and a heat insulation portion connected between the evaporating portion and the condensing portion, wherein an opening area defined by one of the condensing portion and the evaporating portion is larger than an opening area defined by the heat insulation portion;

a capillary structure, disposed on an inner surface of the tube; and

a working fluid, disposed in the tube.

2. The heat pipe as claimed in claim 1, wherein the tube is made of a thermal conductivity material.

3. The heat pipe as claimed in claim 2, wherein the thermal conductivity material comprises metal.

4. The heat pipe as claimed in claim 1, wherein the tube is flat shape.

5. The heat pipe as claimed in claim 4 further comprising a spacer, wherein the spacer is disposed in the tube for supporting two opposite sides of the tube.

6. The heat pipe as claimed in claim 1, wherein the capillary structure is selected from the group consisting of a sintered powder, a metal mesh capillary structure, and a groove type capillary structure.

7. The heat pipe as claimed in claim 6, wherein the sintered powder is disposed on the evaporating portion, the metal mesh capillary structure and the groove type capillary structure are disposed on the condensing portion.

8. The heat pipe as claimed in claim 1, wherein the opening area defined by the condensing portion is larger than the opening area defined by the heat insulation portion.

9. The heat pipe as claimed in claim 8, wherein the opening area defined by the evaporating portion is equal to the opening area defined by the heat insulation portion.

10. The heat pipe as claimed in claim 9, wherein the cross-sectional area of the capillary structure located in the area where the heat insulation portion is perpendicular to the extending direction of the heat pipe is larger than or equal to the cross-sectional area of the capillary structure located in the area where the condensing portion is perpendicular to the extending direction of the heat pipe.

11. The heat pipe as claimed in claim 8, wherein the opening area defined by the evaporating portion is larger than the opening area defined by the heat insulation portion.

12. The heat pipe as claimed in claim 11, wherein the cross-sectional area of the capillary structure located in the area where the heat insulation portion is perpendicular to the extending direction of the heat pipe is larger than or equal to the cross-sectional area of the capillary structure located in the area where the condensing portion and the evaporating portion are perpendicular to the extending direction of the heat pipe.

13. The heat pipe as claimed in claim 1, wherein the heat pipe is line shape, the evaporating portion and the condensing portion are located at two sides of the heat insulation portion respectively.

14. The heat pipe as claimed in claim 1, wherein the heat pipe is U shape, the evaporating portion is located at the middle of the heat pipe, the condensing portion is located at two sides of the heat pipe, the heat insulation portion is located at two curved sections of the heat pipe and connects to the evaporating portion and the condensing portion.