Flat heat pipe structure

The instant disclosure relates to a flat heat pipe structure; more particularly, to a heat-moving flat heat pipe structure having internal support member.

Descriptions of Related Art

As the speed of a central processing unit (CPU) increases, more heat is given off by the CPU. The conventional heat dissipating device comprised of an aluminum heat sink and a fan can no longer accommodate the operational demand of today's CPU with increased clock speed. To address this issue, more powerful and capable heat pipes and vapor chambers have been developed to work with the heat sink.

Due to adhesive characteristic of the porous capillary structure of the heat pipe and pressure differential across its walls, a support member is required to be disposed in the heat pipe, such that the tubing has enough supporting strength after being flattened. However, the conventional support member typically is very rigid and makes the tubing very difficult to bend. According to an issued Taiwan Patent (Patent #577538), a support member having saw tooth-shaped ridges is disclosed. One of the concerns is the capillary structure or the tubing may be worn and/or damaged by these saw tooth-shaped ridges. Some of other existing support members have complex structural features. When these types of support members are disposed in heat pipes, the flow of the working fluid is rerouted from its normal path, which would adversely affect the heat dissipation efficiency.

To address the above issues, the inventors strive via industrial experience and academic research to present the instant disclosure, which can effectively improve the limitations described above.

The instant disclosure provides a flat heat pipe structure having a bendable support member. The support member can prevent the walls of the heat pipe from deforming inwardly and crimping at the bending portions. Thus, the heat pipe is better suited for bending.

Moreover, the instant disclosure provides a flat heat pipe structure having longitudinal passageways, where the path travelled by the working fluid is shortened.

To achieve the aforementioned objects, the heat pipe structure of the instant disclosure comprises a flat tubing and a support member. The flat tubing has two opposed flat main walls and two opposed connecting walls. The main walls are connected by the connecting walls in forming an internal space. A capillary structure is formed on the inner surfaces of the flat tubing. The support member has at least one elongated support arm disposed inside the internal space and extends longitudinally therein. Every support arm has two opposed flat surfaces abutting the capillary structure on the main walls.

Both sides of the support member are spaced apart from the connecting walls by a predetermined distance in the longitudinal direction of the heat pipe. The space created between each side of the support member and the corresponding connecting wall defines a longitudinal passageway for flowing the working fluid.

For advantages, the main walls of the flat heat pipe structure provide additional strength for the annular tubing during the flattening process. After disposing the support member inside the heat pipe structure, the heat pipe structure can be bent without crimping. Moreover, the heat pipe structure and the support member cooperatively form internal passageways for circulating the working fluid. The longitudinal passageways provide a shorter path for the working fluid to travel.

In order to further appreciate the characteristics and technical contents of the instant disclosure, references are hereunder made to the detailed descriptions and appended drawings in connection with the instant disclosure. However, the appended drawings are merely shown for exemplary purposes, rather than being used to restrict the scope of the instant disclosure.

FIG. 1 is a top view of a flat heat pipe structure of the instant disclosure.

FIG. 1A is a cross-sectional view of the flat heat pipe structure in FIG. 1 taken along line AA.

FIG. 2 is a perspective view of a support member for the flat heat pipe structure of the instant disclosure.

FIG. 3 is a perspective view of the flat heat pipe structure of the instant disclosure.

FIG. 4 is a perspective view of a support member for a second embodiment of the instant disclosure.

FIG. 5 is a cross-sectional view of a flat heat pipe structure of the instant disclosure having the support member shown in FIG. 4 .

FIG. 6 is a cross-sectional view of a flat heat pipe structure for a third embodiment of the instant disclosure.

To attain further understanding of the objectives, structural features, and functions of the instant disclosure, please refer to the detailed descriptions provided hereinbelow.

FIG. 1 shows a top view of a flat heat pipe structure 1 of the instant disclosure, and FIG. 1A shows a cross-sectional view thereof taken along line AA in FIG. 1 . The flat heat pipe structure 1 comprises a flat tubing 10 and a support member 20 disposed therein. The flat tubing 10 is made with material with excellent thermal conductivity and malleability such as aluminum, aluminum alloy, copper, copper alloy, etc. The flat tubing 10 is manufactured by flattening an annular tubing. For the instant embodiment, the flat tubing 10 is elongated and has a strip-like shape. Alternatively, the flat tubing 10 may be rectangular with a plate-like shape, where the exact structural shape of the flat tubing 10 is not restricted.

The flat tubing 10 is defined by two opposed main walls 12 and two opposed connecting walls 14 . The connecting walls 14 are connected between the main walls 12 and cooperatively form an internal space 100 . The opposite ends of the flat tubing 10 are welded closed to seal the flat tubing 10 . A capillary structure 16 is formed on the inner surfaces of the flat tubing 10 . Namely, the capillary structure 16 covers the inner surfaces of the main and connecting walls 12 and 14 for transporting the working fluid (not shown). The capillary structure 16 may be provided in various forms such as a metal mesh, grooves, or a sintered body of metal powder.

The support member 20 is preferably made of high temperature resistant and bendable material, such as copper. The support member 20 has at least one support arm 21 disposed in the internal space 100 of the flat tubing 10 . For the instant embodiment, the support member 20 has three support arms 21 arranged in parallel to each other. Each support arm 21 extends along the longitudinal direction or the long axis of the flat tubing 10 . At least one support arm 21 has two opposed flat surfaces, namely, a top surface and a bottom surface, for the orientation shown in FIG. 1A . The top and bottom surfaces abut the capillary structure 16 of the main walls 12 . The support arms 21 serve as structural supports for the flat tubing 10 . Moreover, the support arms 21 and the flat tubing 10 cooperatively form a plurality of passageways 101 , where the passageways 101 are arranged in parallel to each other and extend longitudinally along the flat tubing 10 .

The opposite sides of the support member 20 extending in the longitudinal direction of the flat tubing 10 are spaced apart from the connecting walls 14 by a predetermined distance. In other words, the support arms 21 do not touch the connecting walls 14 . The spaces formed between the support arms 21 and the connecting walls 14 along the longitudinal direction of the flat tubing 10 serve as internal passageways 101 . The passageways 101 are in communication with both ends of the flat heat pipe structure 1 . One end of the flat heat pipe structure 1 being the evaporator section for absorbing heat, and the other end being the condenser section for giving up latent heat of vaporization. At the condenser section, the working fluid changes from a vapor state to a liquid state. These longitudinal passageways 101 provide the shortest distance that the working fluid has to travel between opposite ends of the flat heat pipe structure 1 , thus greatly raising the heat dissipation efficiency. It is worth noting the support arms 21 of the support member 20 may also be arranged touchingly to the respective connecting walls 14 , for preventing the connecting walls 14 from deforming inwardly and crimping after bending.

Please refer to FIG. 2 , which is a perspective view showing the support member 20 of the flat heat pipe structure 1 . As described previously, the support member 20 of the instant embodiment has three support arms 21 . The support arms 21 are parallelly spaced apart from one another, where the number of support arms 21 is not restricted. The support member 20 may have more than one support arm 21 , where the support arms 21 are equally spaced from one another inside the flat tubing 10 . The distance between adjacent support arms 21 depends on the dimension of the flat tubing 10 along the short axis of the flat tubing 10 . The support member 20 further has a connecting portion 22 connecting to one end of each support arm 21 . The width of the connecting portion 22 is substantially equal to or less than the width of the internal space 100 along the short axis of the flat tubing 10 . Furthermore, the opposite ends of the connecting portion 22 do not have to extend normally beyond the support arms 21 . The purpose of the connecting portion 22 is to maintain the support arms 21 spaced apart from each other. Especially after the support arms 21 have been disposed in the annular tubing, the connecting portion 22 prevents the misplacing of the support arms 21 during the flattening process. For the instant embodiment, the shape of the connecting portion 22 is rectangular but is not restricted thereto. For example, the connecting portion 22 may be a rod-shaped structure. Alternatively, the support member 20 may have two connecting portions 20 . The second connecting portion 20 may be arranged on the other end of each support arm 21 .

Please refer to FIG. 3 , which is a perspective view of the flat heat pipe structure 1 of the instant disclosure. The connecting portion 22 is arranged proximate to one end of the flat tubing 10 . During the flattening process of the annular tubing, the support member 20 provides structural support to the main walls 12 , thus preventing the main walls 12 from deforming inwardly or crimping. Whereas during the bending process of the flat tubing 10 , the support member 20 also allows the main walls 12 to maintain smooth surfaces. The other advantage of the instant disclosure is the formation of longitudinal passageways 101 . The passageways 101 provide a shorter path for the working fluid to travel between the ends of the flat tubing 10 .

Please refer to FIG. 4 , which is a perspective view showing an alternate support member 20 a . For the support member 20 a , a second capillary structure 23 is formed on the opposed side surfaces of each support arm 21 . Similarly, the capillary structure 23 may be provided in various forms such as a metal mesh, grooves, a sintered body of metal powder, or a composite capillary structure.

Please refer to FIG. 5 , which is a cross-sectional view of the support member 20 a shown in FIG. 4 and a flat heat pipe structure 1 a . Based on the aforementioned structural features of the support member 20 a , the capillary structures 16 and 23 cooperatively surround the passageways 101 . In other words, the inners walls that define each passageway 101 are covered with capillary structures. The addition of the second capillary structure 23 further enhances the heat dissipation efficiency of the heat pipe structure 1 a.

Please refer to FIG. 6 , which is a cross-sectional view showing a heat pipe structure 1 b for a third embodiment of the instant disclosure. The instant embodiment is particularly suitable in cases where a heat pipe is required to be bent. The width or the lateral dimension of the heat pipe structure 1 b is not restricted. When the internal space 100 within the heat pipe structure 1 b is more limited, the heat pipe structure 1 b may include only one support arm 21 b , as illustrated in FIG. 6 . Moreover, the single support arm 21 b and a flat tubing 10 b cooperatively form two longitudinal passageways 101 .

Based on the foregoing descriptions, the main walls 12 provide additional strength for the annular tubing during the flattening process. The instant disclosure is especially suitable in cases where a heat pipe is required to be bent. A smooth surface can be maintained at the bent portion of the flat heat pipe structure without crimping. Especially for large sized flat heat pipe structure, a smooth surface can be maintained across the main walls 12 . Moreover, after the support member has been disposed in the flat heat pipe structure, the heat pipe structure can still be bent as needed. In addition, the formation of longitudinal passageways provides a short path for transporting the working fluid.

The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims