TWI494531B - Flat heat pipe and method for manufacturing the same - Google Patents

Description

Flat heat pipe and method of manufacturing same

The present invention relates to a heat pipe, and more particularly to a flat heat pipe applied to the field of heat dissipation of electronic components and a method of manufacturing the same.

At this stage, the heat pipe has been widely used in electronic components with large heat generation because of its high heat transfer capacity. When the heat pipe is in operation, the low-boiling working medium filled inside the pipe body absorbs the heat generated by the heat-generating electronic component in the evaporation portion, and then evaporates and vaporizes, the vapor moves with heat to the condensation portion, and condenses and condenses in the condensation portion to release the heat. Thereby dissipating heat from the electronic components. The liquefied working medium is returned to the evaporation portion under the action of the capillary structure of the heat pipe wall, and further evaporative vaporization and liquefaction condensation are performed, so that the working medium circulates inside the heat pipe, and the heat generated by the electronic component is continuously emitted.

The capillary structure of the conventional heat pipe can be generally classified into a groove type, a sintered type, a fiber type, and a wire mesh type, and the characteristics of the capillary structures are single, and the permeability of the groove type, the fiber type, and the wire mesh type capillary structure is high. The thermal resistance is small, but the capillary force is weak, and the maximum heat transfer loss after flattening is large; the sintered capillary structure has strong capillary force and good anti-gravity effect, and the maximum heat transfer loss after flattening is small, but its permeability Low, high thermal resistance.

In view of this, it is necessary to provide a flat heat pipe for improving the performance of the heat pipe and its manufacture. method.

A flat heat pipe comprising a hollow flat tube body and a first capillary structure and a second capillary structure disposed in the tube body, the first capillary structure being different from the structure of the second capillary structure, the first capillary structure being composed of a thread Braiding, the second capillary structure is formed by sintering a metal powder, the first capillary structure is bonded to one side of the tube body, and the second capillary structure is bonded to the other side of the tube body, The first capillary structure and the second capillary structure are in contact with each other, and the tube body forms a vapor passage on each side of the first capillary structure and the second capillary structure.

A method for manufacturing a flat heat pipe, comprising the steps of: providing a rod body having a cylindrical shape, an opening and a notch formed on an outer circumferential surface thereof, the opening being disposed opposite to the notch; providing a first capillary structure; Providing a circular tube, the circular tube is hollow, the inner diameter of the circular tube is equal to the outer diameter of the rod body, and the rod body and the first capillary structure are inserted into the round tube to make the first The capillary structure is located in the opening of the rod body; the metal powder is filled into the notch of the rod body located in the circular tube, and the metal powder is sintered at a high temperature to form a second capillary structure; the rod body is taken out, the first and the first a second capillary structure is disposed in the circular tube, the first and second capillary structures are disposed opposite to each other, and are respectively attached to a part of the inner wall of the circular tube; and the round tube is flattened to form a flat heat pipe, The second capillary structure is attached to the first capillary structure, and the flat heat pipe forms a vapor channel on each side of the first capillary structure and the second capillary structure.

In the above flat heat pipe and the method of manufacturing the same, the first capillary structure is disposed on one side of the tube body, and the second capillary structure is disposed on the other side of the tube body, and the first, The second capillary structures are in contact with each other, and when the heat pipe is in operation, the working medium can penetrate each other between the first and second capillary structures, and has a large The capillary force has a high permeability and a small heat resistance, so that the heat pipe has good heat transfer performance.

10, 20, 30, 40‧‧‧ flat heat pipes

101‧‧‧Evaporation section

102‧‧‧Condensation section

11‧‧‧Body

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

12, 22, 32, 42, 15, 15a, 15c‧‧‧ first capillary structure

13, 23, 33, 43, 17, 17b‧‧‧Second capillary structure

14, 14a, 14b, 14c‧‧‧ rods

141, 141a, 141c‧‧

142, 142b‧‧ ‧ gap

16‧‧‧ round tube

171‧‧‧ Straight side

172‧‧‧Arc edge

18, 18a, 18b, 18c‧‧‧ circular heat pipes

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of a flat heat pipe according to a first embodiment of the present invention.

2 is a schematic transverse cross-sectional view of the flat heat pipe of FIG. 1 taken along line II-II.

3 is a flow chart of a method of manufacturing the flat heat pipe shown in FIG. 1.

4 is a schematic perspective view of a rod body and a round tube in the manufacturing method shown in FIG. 3.

Fig. 5 is a schematic transverse cross-sectional view of the rod body taken along line V-V in the manufacturing method shown in Fig. 4.

Figure 6 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 3.

Fig. 7 is a schematic transverse cross-sectional view showing a rod body in another manufacturing method of the heat pipe shown in Fig. 1.

Figure 8 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 7.

Figure 9 is a transverse cross-sectional view showing a flat heat pipe according to a second embodiment of the present invention.

Figure 10 is a transverse cross-sectional view showing a flat heat pipe according to a third embodiment of the present invention.

Figure 11 is a schematic transverse cross-sectional view of a rod body in a method of manufacturing the flat heat pipe shown in Figure 10.

Figure 12 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 11.

Figure 13 is a schematic transverse cross-sectional view of a rod body in another manufacturing method of the flat heat pipe shown in Figure 10.

Figure 14 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 13.

Figure 15 is a transverse cross-sectional view showing a flat heat pipe according to a fourth embodiment of the present invention.

The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.

1 and 2 show a flat heat pipe 10 according to a first embodiment of the present invention. The heat pipe 10 includes an elongated flat tube body 11 and a first capillary structure 12 longitudinally disposed in the tube body 11. And a second capillary structure 13, and an appropriate amount of working medium (not shown) injected into the tube body 11. The heat pipe 10 has an evaporation section 101 and a condensation section 102 along the length direction. The evaporation section 101 and the condensation section 102 are respectively disposed at two ends of the tube body 11.

The tube body 11 is made of a material having good thermal conductivity such as copper, which can transfer external heat to the inside. The tube body 11 has a hollow seal shape, and an inner space 110 is formed therein. The tube body 11 is formed by flattening a hollow tube. The tube body 11 includes a top plate 111, a bottom plate 112 and two side plates 113, 114. The top plate 111 and the bottom plate 112 are parallel to each other and are vertically opposed to each other. The two side plates 113 and 114 are arc-shaped, and are respectively located at two sides of the pipe body 11 and connected to the top plate 111 and the bottom plate 112, so that the pipe body 11 is in contact with A longitudinally vertical cross section forms a runway-like profile.

The first capillary structure 12 has a longitudinal structure which is flattened into a flat solid shape by the second capillary structure 13. The first capillary structure 12 is formed with a plurality of fine pores (not shown), and the pores can be made of copper. A wire made of a material such as stainless steel or fiber is formed by weaving. In the present embodiment, the first capillary structure 12 is woven by a copper wire to form a multilayered mesh laminated to each other in the radial direction thereof. The first capillary structure 12 has a large porosity, so that the permeability is high and the thermal resistance is small, which facilitates the smooth flow of the working medium therein. Of course, the first capillary structure 12 can also be a woven single-layer mesh structure.

The first capillary structure 12 is disposed on one side of the middle portion of the tubular body 11. In this embodiment, the bottom surface of the first capillary structure 12 is closely attached to the inner surface of the bottom plate 112 of the tubular body 11, and the top surface thereof is coupled to the second capillary structure 13.

The second capillary structure 13 is different from the first capillary structure 12 in that it is sintered by a metal powder such as copper to form a porous shape. The second capillary structure 13 has small internal pores, large evaporation surface area, strong capillary force and good anti-gravity effect. And the maximum heat loss loss after flattening is small, which contributes to the evaporation endothermic of the working medium, thereby effectively transferring the heat of the evaporation section 101 of the heat pipe 10. The second capillary structure 13 is disposed on the other side of the tube body 11 opposite to the first capillary structure 12, that is, the second capillary structure 13 is facing the first capillary structure 12, the second capillary The dimension of the structure 13 attached to one side of the first capillary structure 12 is smaller than the dimension of the side of the second capillary structure 13 away from the first capillary structure 12. In this embodiment, the second capillary structure 13 has a substantially triangular prism shape, and the top surface of the larger size is closely adhered to the inner surface of the top plate 111 of the tube body 11 by high-temperature sintering, and the size is small. The bottom side forms a tip and fits in the middle of the top surface of the first capillary structure 12.

The first and second capillary structures 12 and 13 are laminated on top of each other, and the internal space 110 of the tubular body 11 is divided into two in the longitudinal direction, so as to be on both sides of the first and second capillary structures 12 and 13 A vapor passage 118 is formed which allows vapor to pass therethrough.

The working medium is a substance having a lower boiling point such as water, wax, alcohol or methanol. When the evaporation section 101 of the heat pipe 10 is in contact with a heat source (not shown), the working medium absorbs heat from the evaporation section 101 to evaporate, and moves to the condensation section 102 through the vapor passage 118, and condenses after the condensation section 102 releases heat. The liquid releases the heat and completes the heat dissipation from the heat source. The first and second capillary structures 12, 13 provide a capillary force to return the working medium formed by the condensation of the condensation section 102 of the pipe body 11 to the evaporation section 101, thereby achieving a circulating motion of the working medium in the pipe body 11 to complete the heat source. Continuous cooling.

In the heat pipe 10, the first capillary structure 12 is formed by weaving a wire, and the One side of the tube body 11 (the inner surface of the bottom plate 112), and the second capillary structure 13 is formed by sintering of metal powder, which is disposed on the other side (the inner surface of the top plate 111) inside the tube body 11, And the first and second capillary structures 12 and 13 are located in the middle of the tube body 11 and are laminated on each other. When the heat pipe 10 is in operation, the working medium is in the first and second capillary structures 12 and 13 Interpenetrating, having a large capillary force due to the sintered second capillary structure 13, and having a higher permeability and a smaller thermal resistance due to the woven first capillary structure 12, thereby making the heat pipe 10 Has good heat transfer performance. The heat pipe 10 can have a thickness of less than 2 mm, and even when the thickness of the heat pipe 10 is 1.8 mm, the heat pipe 10 can ensure good performance, and is suitable for electronic devices such as notebook computers having a small internal space.

The heat transfer performance of the heat pipe 10 of the present invention is better than that of the conventional heat pipe by the specific experimental data. The following tests are carried out under the same conditions. The specifications and parameters of the heat pipes in the same table are the same. Among them, Qmax is the maximum heat transfer capacity when the heat pipe operating temperature is 50 °C, and the average heat resistance value Rt=(the average temperature of the evaporation section) (Condensation section average temperature) / Qmax.

As shown in Table 1, in the case of being flattened to the same specification (thickness T = 2.0 mm), the average maximum heat transfer amount of the heat pipe 10 of the present invention is increased by about 57% compared with the conventional grooved heat pipe. It is known that the sintered heat pipe is increased by about 27%, and the average heat resistance value is reduced by about 36% compared with the conventional grooved heat pipe, and is reduced by about 22% compared with the conventional sintered heat pipe. Therefore, the heat pipe of the present invention is 10 The maximum heat transfer loss after flattening is small, the average thermal resistance value is also small, and its comprehensive performance is significantly improved.

As shown in Table 2, in the case of being flattened to the same specification (thickness T = 1.8 mm), the average maximum heat transfer amount of the heat pipe 10 of the present invention is increased by about 57% compared with the conventional grooved heat pipe. It is known that the sintered heat pipe is increased by about 28%, and the average heat resistance value is reduced by about 36% compared with the conventional grooved heat pipe, and is reduced by about 22% compared with the conventional sintered heat pipe. Therefore, the heat pipe of the present invention is 10 The maximum heat transfer loss after flattening is small, the average thermal resistance value is also small, and its comprehensive performance is significantly improved.

3 to 6 show a manufacturing method of the heat pipe 10, which includes the following steps: providing a rod body 14, as shown in Figs. 4 and 5, the rod body 14 has a cylindrical shape on the outer circumferential surface thereof. The bottom portion of the rod body 14 defines an opening 141 in the axial direction, and the top portion of the rod body 14 on the outer circumferential surface is directly cut off a small portion at the opening 141 so as to be on the outer circumferential surface of the rod body 14. Forming a flat notch 142 at the top, the notch 142 is not in communication with the opening 141; providing a hollow capillary-shaped first capillary structure 15 (please refer to FIG. 6), the first The capillary structure 15 is placed in the opening 141 of the rod body 14; a hollow metal tube 16 is provided, the inner diameter of the tube 16 is approximately equal to the outer diameter of the rod body 14, the rod body 14, the first capillary structure 15 is inserted into the circular tube 16; the metal powder is filled into the notch 142 of the rod body 14 located in the circular tube 16, and when the metal powder is filled, the metal powder having a fine particle size can be filled first, and then the grain is gradually filled. The metal powder having a relatively large diameter vibrates the circular tube 16 so that the metal powder is distributed along the longitudinal direction of the circular tube 16 by the gravity factor. After filling, the metal powder is sintered at a high temperature to form a second capillary structure 17, the second capillary The cross-sectional mask of structure 17 has a straight edge 171 and a curved edge 172 connected to the straight edge 171, wherein the curved edge 172 is adhered to the inner surface of the circular tube 16; the rod body 14 is removed, as shown in FIG. As shown, the first and second capillary structures 15, 17 are left in the circular tube 16, and the first and second capillary structures 15, 17 are disposed opposite to each other and are respectively attached to a part of the inner wall of the circular tube 16. Filling the tube 16 with a working medium, evacuating and closing the longitudinal ends of the tube 16 to form a circular heat pipe 18; the first and second capillary structures 15, 17 are directly opposite to the circular heat pipe 18 to form the heat pipe 10 in the first embodiment, wherein the round pipe 16 is flattened to form a flat tube The second capillary structure 17 is flattened to form a second capillary structure 13 having a substantially triangular prism shape. The smaller side of the second capillary structure 13 , that is, the bottom side is attached to the first capillary structure 17 . On the top surface, the first capillary structure 15 is pressed by the second capillary structure 17 to form a flat solid first capillary structure 12.

In the above manufacturing method, the notch 142 of the rod body 14 is straight, which can be directly milled by a milling machine, and has low cost and is convenient for mass production.

7 and 8 show another manufacturing method of the above heat pipe 10, which is similar to the above manufacturing method, except that the opening 141a of the bottom of the rod body 14a is formed in a straight shape similar to the top notch 142. The first capillary structure 15a is a hollow elliptical shape. The rod body 14a is inserted into the circular tube 16 before the circular heat pipe 18a is formed. The first capillary structure 15a is inserted into the opening of the rod body 14a in the circular tube 16. In 141a. In the manufacturing method of the embodiment, the opening 141a and the notch 142 of the rod body 14a are both straight, and can be directly milled by a milling machine, thereby further reducing the production cost.

Figure 9 shows a heat pipe 20 in a second embodiment of the present invention, which heat pipe 20 is similar to the heat pipe 10 of the first embodiment, except that the first capillary structure 22 is provided in the pipe body. The second capillary structure 23 is obliquely aligned with the first capillary structure 22, and the second capillary structure 23 is not adjacent to the top plate 111 of the tubular body 11 (in the figure) The left side surface is closely attached to the right side of the top surface of the first capillary structure 22. Of course, the first capillary structure 22 may also be disposed at a position to the right in the middle of the tube body 11. The second capillary structure 23 is not closely attached to a side surface (ie, the right side surface) of the top plate 111 of the tube body 11. It is attached to the left side of the top surface of the first capillary structure 22.

When manufacturing the heat pipe 20, it is only necessary to align the first capillary structures 15, 15a and the second capillary structure 17 in Figs. 6 and 8 obliquely to round the circular heat pipes 18, 18a.

Figure 10 is a view showing a heat pipe 30 according to a third embodiment of the present invention, which is similar to the heat pipe 10 of the first embodiment, except that the second capillary structure 33 has a rectangular parallelepiped shape, The top surface is closely attached to the inner surface of the top plate 111 of the tube body 11, and the center of the bottom surface is attached to the top surface of the first capillary structure 32.

11 and 12 show a method of manufacturing the heat pipe 30 described above, which is similar to the method of manufacturing the heat pipe 10 shown in FIGS. 3 to 6, except that the top of the rod 14b is The cross section of the notch 142b is rainbow-shaped, and the cross section of the corresponding second capillary structure 17b in the circular heat pipe 18b is also rainbow-shaped. The second capillary structure 17b is flattened to form a substantially rectangular parallelepiped shape. Two capillary structure 33.

13 and FIG. 14 show another manufacturing method of the heat pipe 30 described above, which is similar to the manufacturing method of the heat pipe 30 shown in FIGS. 11 and 12, except that the opening 141c of the bottom of the rod 14c is Formed in a straight shape, the first capillary structure 15c is a hollow elliptical shape, and the rod body 14c is inserted into the circular tube 16 before the circular heat pipe 18c is formed, and the first capillary structure 15c is inserted into the rod in the circular tube 16. In the opening 141c of the body 14c.

Figure 15 is a view showing a heat pipe 40 in a fourth embodiment of the present invention, which is similar to the heat pipe 30 in the third embodiment, except that the first capillary structure 42 is provided in the pipe body. The second capillary structure 43 is obliquely aligned with the first capillary structure 42 in the left portion of the middle portion of the inner surface of the tube 11. The second capillary structure 43 is not closely attached to the left side of the bottom surface of the tube body 11 to which the top plate 111 is attached. It is fitted to the top surface of the first capillary structure 42. Of course, the first capillary structure 42 can also be disposed at a right position in the middle of the tube body 11. The second capillary structure 43 is not closely attached to the right side of the bottom surface of the tube body 11 to which the top plate 111 is attached. The top surface of the first capillary structure 42.

When manufacturing the heat pipe 40, it is only necessary to align the first capillary structures 15, 15c and the second capillary structure 17b in Figs. 12 and 14 obliquely to round the circular heat pipes 18b, 18c.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

10‧‧‧flat heat pipe

11‧‧‧Body

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

12‧‧‧First capillary structure

13‧‧‧Second capillary structure

Claims (19)

A flat heat pipe comprising a hollow flat tube body and a first capillary structure and a second capillary structure disposed in the tube body, wherein the first capillary structure is different from the second capillary structure, the first The capillary structure is formed by weaving a wire, and the second capillary structure is formed by sintering a metal powder having a fine particle diameter and a metal powder having a relatively large particle diameter in a tube, and the first capillary structure is bonded to the tube. On one side of the body, the second capillary structure is bonded to the other side of the tube body, and the first capillary structure and the second capillary structure are attached to each other, and the tube body is in the first capillary structure and the first capillary structure A vapor channel is formed on each side of the two capillary structures. The flat heat pipe according to claim 1, wherein the pipe body comprises a top plate and a bottom plate opposite to the top plate, and one side of the first capillary structure is coupled to the bottom plate of the pipe body, One side of the second capillary structure is coupled to the top plate of the pipe body, the first capillary structure is not bonded to the other side of the bottom plate of the pipe body, and the second capillary structure is not bonded to the top plate of the pipe body. The other side of the upper side fits together. The flat heat pipe of claim 1, wherein the first capillary structure is disposed opposite to the second capillary structure, and the second capillary structure is attached to the middle of the first capillary structure or The middle of the second capillary structure is attached to the first capillary structure. The flat heat pipe of claim 3, wherein a side of the second capillary structure that is attached to the first capillary structure is smaller than a size of the second capillary structure away from the first capillary structure. The side of the second capillary structure conforming to the first capillary structure forms a tip end and is fitted in the middle of the first capillary structure. The flat heat pipe according to claim 3, wherein the second capillary structure has a rectangular parallelepiped shape, and a center of the second capillary structure is attached to the first capillary structure. The flat heat pipe according to claim 1, wherein the first capillary structure is disposed obliquely in alignment with the second capillary structure, and the second capillary structure is attached to one side of the first capillary structure. Or one side of the second capillary structure is attached to the first capillary structure. The flat heat pipe of claim 6, wherein a side of the second capillary structure that is attached to the first capillary structure is smaller than a size of the second capillary structure away from the first capillary structure. One side of the size, the second capillary structure is attached to one side of the first capillary structure. The flat heat pipe according to claim 6, wherein the second capillary structure has a rectangular parallelepiped shape, and one end of the second capillary structure is attached to the first capillary structure. The flat heat pipe according to claim 1, wherein the second capillary structure is a triangular prism shape or a rectangular parallelepiped shape, and the other side of the second capillary structure not bonded to the tubular body is attached to the same Said on the first capillary structure. The flat heat pipe of claim 1, wherein the first capillary structure is extruded into a flat shape by the second capillary structure. A method for manufacturing a flat heat pipe, comprising the steps of: providing a rod body having a cylindrical shape, wherein an outer surface of the rod body is provided with an opening and a notch, and the opening is disposed opposite to the notch; a capillary structure; the round tube is hollow, the inner diameter of the round tube is equal to the outer diameter of the rod body, and the rod body and the first capillary structure are inserted into the round tube, so that The first capillary structure is located in the opening of the rod body; the metal powder having a fine particle diameter and the metal powder having a relatively large particle diameter are successively filled into the notch of the rod body located in the circular tube, and the metal powder is Sintering at a high temperature to form a second capillary structure; taking out the rod body, the first and second capillary structures are left in the round tube, the first and second capillary structures are disposed opposite to each other, and are respectively attached to the circle Part of the inner wall of the tube; and Flattening the round tube to form a flat heat pipe, the second capillary structure is attached to the first capillary structure, and the flat heat pipe is formed on both sides of the first capillary structure and the second capillary structure Vapor channel. The method for manufacturing a flat heat pipe according to claim 11, wherein the notch has a rainbow cross shape, and the second capillary structure is transversely before the rod is taken out and the circular tube is flattened. The cross section corresponds to a rainbow shape. The method for manufacturing a flat heat pipe according to claim 12, wherein the second capillary structure is a rectangular parallelepiped shape after the round pipe is flattened. The method for manufacturing a flat heat pipe according to claim 11, wherein the notch is a flat shape, and the second capillary structure has a straight side before the rod is removed after the rod body is taken out. And an arcuate edge connected to the straight edge, the arcuate edge being bonded to an inner surface of the circular tube. The method for manufacturing a flat heat pipe according to claim 14, wherein a size of a side of the second capillary structure that is bonded to the first capillary structure is smaller than the first portion after the round tube is flattened The second capillary structure is away from the size of one side of the first capillary structure. The method for manufacturing a flat heat pipe according to claim 11, wherein the notch is arched, and the first capillary structure is hollow and round before the round pipe is flattened. The method for manufacturing a flat heat pipe according to claim 11, wherein the notch is a flat shape, and the first capillary structure is a hollow ellipse before the round tube is flattened. The method of manufacturing a heat pipe according to claim 11, wherein the first capillary structure is formed into a flat shape by extrusion of the second capillary structure during the process of flattening the circular tube. The method of manufacturing a flat heat pipe according to claim 11, wherein when the round pipe is flattened, the first capillary structure and the second capillary structure are aligned in an oblique or oblique direction.