Heat pipe, method for manufacturing the same, and device

A heat pipe operating noiselessly by preventing, or reducing the effects of, the mixing of working fluid at different temperatures includes a hollow tube, a capillary structure, a working fluid, and a bushing. The porous capillary structure able to carry the fluid is disposed on an inner wall of the tube. The bushing is hollow, and the bushing is disposed on a surface of the capillary structure away from the tube. The heat pipe is divided into evaporation, adiabatic, and condensation sections, the capillary structure being at all sections. The working fluid is disposed in the capillary structure of the evaporation section, the bushing is disposed on a side of the capillary structure of the adiabatic section.

FIELD

The subject matter herein generally relates to manufacturing processes, a method for manufacturing a heat pipe, and a device.

BACKGROUND

Devices using heat pipes, such as mechanical equipment, electronic products, etc., include heat-generating components. A heat pipe may be included in such a device for dissipating heat from the heat-generating components. The heat pipe is divided into an evaporation section, an adiabatic section, and a condensation section connected in this order. A working fluid flows from the evaporation section, the adiabatic section, and into the condensation section to dissipate the heat.

The amount of the working fluid in the heat pipe can be increased to increase the heat dissipation efficiency of the heat pipe. When the heat pipe is in operation, the working fluid evaporates in the evaporation section into gas form. The gas flows through the adiabatic section to the condensation section under the action of a small pressure difference, releases heat and condenses into liquid, and the liquid is taken back to the evaporation section. However, with the increased amount of the working fluid, when the working fluid is not completely vaporized in the evaporation section, the working fluid in the evaporation section and the condensation section will collide in the adiabatic section, which may cause noise. Therefore, there is a room for improvement.

DETAILED DESCRIPTION

Referring toFIG.8andFIG.12, a heat pipe100is provided in an embodiment.

The heat pipe100includes a tube10, a capillary structure20, a working fluid50, and a bushing30. The tube10is hollow. The capillary structure20is disposed on an inner wall of the tube10. The working fluid50is disposed in the capillary structure20. The bushing30is hollow and disposed on a surface of the capillary structure20away from the tube10. The heat pipe100is divided into an evaporation section11, an adiabatic section12, and a condensation section13, connected in this order. The capillary structure20is disposed at or in the evaporation section11, the adiabatic section12, and the condensation section13. The working fluid50is disposed in and infills the capillary structure20of the evaporation section11. The bushing30is disposed on a side of the capillary structure20of the adiabatic section12.

During use, the working fluid50of the evaporation section11collects heat and is thereby vaporized to form gas. The gas carrying heat flows through the bushing30of the adiabatic section12to the condensation section13. Upon losing heat, the gas is liquefied and transformed into liquid in the condensation section13. The liquid passes through the capillary structure20of the adiabatic section12back to the evaporation section11. When the working fluid50in the heat pipe100is not completely vaporized, the non-vaporized working fluid50and the vaporized gas pass through the bushing30. The liquefied fluid in the condensation section13flows through the capillary structure20disposed outside the bushing30. Therefore, the bushing30prevents the non-vaporized working fluid50and the liquefied working fluid50from mixing and colliding with each other, and noise is thus avoided. In addition, the bushing30allows the addition of more working fluid50, so heat dissipation performance and efficiency of the heat pipe100are improved.

The tube10is made of metal material with good thermal conductivity, such as copper or aluminum.

The shape of the tube10can be set as required. For example, the tube10can be a round tube, a square tube, or a flat tube. The tube10is hollow, so that the working fluid50can circulate, absorb heat to evaporate into gas, and carry the heat.

In an embodiment, an inner wall of the tube10is smooth. In another embodiment, the inner wall of the tube10can define grooves to facilitate the adsorption of liquid.

The capillary structure20is made of metal, such as copper or aluminum. The capillary structure20is formed by metal powders, metal braided wires, or metal braided meshes. The capillary structure20is porous to facilitate the flow of the working fluid50.

The bushing30is hollow to facilitate a passage of the gas. The bushing30is made of metal. The bushing30is spaced apart from the tube10. The bushing30and the tube10are connected by a capillary structure20of the adiabatic section12.

In an embodiment, the tube10is integrally formed or composed of multiple sections. The bushing30is tubular or sheet-shaped.

A thickness of the capillary structure20can be set according to a required heat dissipation efficiency, volume, cost, and usage environment of the heat pipe100.

An inner wall of the bushing30is smooth. Thus, a resistance of gas passing through the bushing30can be reduced, so that the gas carrying heat can pass through the bushing30quickly, thereby reducing a thermal resistance of the heat pipe100.

Referring toFIG.8, in an embodiment, an inner diameter D1of the capillary structure20of the evaporation section11is greater than or equal to an inner diameter D2of the bushing30and smaller than an outer diameter D2′ of the bushing30. An inner diameter D3of the capillary structure20of the condensation section13is equal to an inner diameter D2of the bushing30.

Referring toFIG.12, in an embodiment, each of the inner diameter D1of the capillary structures20of the evaporation section11and the inner diameter D3of the capillary structures20of the condensation section13is equal to the inner diameter D2of the bushing30.

Referring toFIGS.1to8, a method for the manufacturing of the heat pipe100is provided in accordance with an embodiment. The method is provided by way of example, as there are a variety of ways to carry out the method. Referring toFIG.13, the method can begin at block1.

In block1, referring toFIGS.1to2, a tube10and a bushing30are provided. An inner diameter of the tube10is greater than an outer diameter of the bushing30. The tube10comprises a first area I, a second area II, and a third area III connected in this order.

The tube10and the bushing30are both hollow.

A length of the tube10is greater than a length of the bushing30. The inner diameter of the tube10is larger than the outer diameter of the bushing30, so that the bushing30can be received in the tube10.

The tube10and the bushing30are made of metal materials with good thermal conductivity, such as copper or aluminum.

In block2, referring toFIGS.3to7, a capillary structure20is formed on the inner wall of the tube10in the first area I, the second area II, and the third area III. The bushing30is disposed on the surface of the capillary structure20in the second area II away from the tube10.

In an embodiment, referring toFIG.14, block2can be carried out as follows.

In block211, referring toFIG.3, an end of the tube10disposed in the first area I is narrowed, and a first mandrel41is inserted into the tube10from the other end of the tube10.

A diameter of the first mandrel41is smaller than the inner diameter of the tube10, so that the first mandrel41can be inserted into the tube10.

An inner diameter of a narrowed end of the tube10in the first area I is smaller than the diameter of the first mandrel41, so that the first mandrel41can be inserted into the tube10from the other end of the tube10and then abut against one end of the tube10. A gap60ais formed between the narrowed end of the tube10and the first mandrel41. The gap60acan be infilled with metal material26.

In block212, referring toFIGS.4to5, metal material26fills a space between the first area I and the first mandrel41. The metal material26surrounds the first mandrel41. The metal material26is sintered to form a first capillary structure22, and then the first mandrel41is removed.

The metal material26is metal powders, metal braided wires, or metal braided meshes. The metal material26is made of metal, such as copper or aluminum. In an embodiment, the metal material26is copper with certain toughness, rendering the metal material26easy to be processed and shaped.

The metal material26is disposed in the gap60aformed between the tube10and the first mandrel41, and the metal material26surrounds the first mandrel41. In an embodiment, along an extending direction of the tube10, a length of the metal material26filling the tube10and the first mandrel41is a quarter of a length of the tube10. In other embodiments, the length of the metal material26filling the gap60acan be set as required.

A sintering temperature is lower than a melting point of the metal, so that the metal material26is less than solid during the sintering process, and the metal material26forms a capillary structure20with pores. In some embodiments, the metal material26is copper, and is sintering temperature from 900° C. to 1000° C., for example, 930° C., 960° C., or 990° C. After sintering, the metal material26forms a porous first capillary structure22, that is, the evaporation section11is thereby formed.

In block213, referring toFIGS.6to7, the bushing30is inserted into the second area II. A second mandrel42is inserted into the bushing30, causing the second mandrel42to extend to the third area III. A metal material26is infilled in the space between the tube10and the bushing30, and between the tube10and the second mandrel42. The metal material26is sintered to become a second capillary structure24, and then the second mandrel42is removed.

The bushing30is disposed in the second area II of the tube10. An outer diameter D2′ of the bushing30is greater than the inner diameter D1of the first capillary structure22. One end of the bushing30abuts against one end of the first capillary structure22of the first area I. A gap60bis formed between the bushing30and the tube10of the second area II. The second mandrel42extends from one end of the bushing30to the third area III. A gap60cis formed between the second mandrel42and the tube10of the third area III. The metal material26is sintered after infilling the gap60band the gap60c, and the sintered metal material26forms the second capillary structure24.

In an embodiment, one end of the second mandrel42extends from the end of the bushing30adjacent to the first area I to the first area I, and further passes through the first capillary structure22to abut the end of the tube10. Thus, during forming the second capillary structure24, the first capillary structure22is integrally complete, for example, metal powders are not scattered. In an embodiment, the inner diameter D1of the first capillary structure22is equal to the outer diameter D2′ of the bushing30.

When the capillary structure20is formed by the above two-step sintering process, the inner diameter D1of the capillary structure20of the first area I may be greater than or equal to the inner diameter D2of the bushing30, but smaller than the outer diameter D2′ of the bushing30. The inner diameter D3of the capillary structure20of the third area III is equal to the inner diameter D2of the bushing30. That is, a relationship between the capillary structure20and a content of the working fluid50can be adjusted by controlling a thickness and/or length of the capillary structure20in each area, a size of the bushing30(such as length, thickness, inner diameter, outer diameter, etc.), or the size relationship between the bushing30and the capillary structure20, etc. Thus, the heat dissipation efficiency of the heat pipe100is controlled to meet different heat dissipation requirements.

Since the metal material26shrinks during the sintering process, the above two-step sintering process can adjust a position of the bushing30, thereby controlling the sintering quality of the heat pipe100. In addition, the relationship between the capillary structure20and the content of the working fluid50can also be controlled to adjust the heat dissipation efficiency of the heat pipe100.

In some embodiments, the bushing30may include multiple sections. Each section of the bushing30is tubular or sheet-shaped. In some embodiments, a sheet or ribbon of metal may be wound on the surface of the second mandrel42to form an annular bushing30.

In some embodiments, before the capillary structure20is formed on the inner wall of the tube10, the tube10and the bushing30are first washed with chemical reagents, to remove oil on the surface of the tube10and the bushing30. Thus, the metal material26can adhere on the inner wall of the tube10and the bushing30more firmly.

In block3, referring toFIG.8, a working fluid50is injected into the capillary structure20of the first area I. Air is evacuated from the tube10to create vacuum in the tube10, and the tube10is sealed to obtain the heat pipe100.

In an embodiment, the tube10of the third area III is narrowed by an argon arc welding device for example. In some embodiment, a metal oxide produced during welding can be reduced to metal in a high-temperature furnace filled with oxy-reducing gas. Since a thermal conductivity of the metal oxide is lower than that of the metal, the greater purity of metal instead of metal oxide improves the thermal conductivity of the heat pipe100.

The working fluid50is injected into the capillary structure20of the first area I. The working fluid50is water, acetone, or ethanol.

After the working fluid50is injected, the vacuum treatment is performed, and then an argon arc welding device is used to seal the tube10of the first area I. The vacuum treatment improves the thermal conductivity of the heat pipe100.

Referring toFIGS.9to10, in another embodiment, in the process of forming the heat pipe100a, before inserting the bushing30and the second mandrel42into the tube10, the steps of sintering and removing the first mandrel41may be omitted. That is, the evaporation section11(first area I), the adiabatic section12(second area II), and the condensation section13(third area III) can be formed at the same time through a single sintering process.

In an embodiment, referring toFIG.15, the block of2can be carried out as follows.

In block221, referring toFIG.9, the tube10at one end of the first area I is narrowed and a first mandrel41ais inserted into the tube10from the other end of the tube10, causing the first mandrel41ato extend to the third area III. The bushing30is wrapped around the first mandrel41aand is disposed in the second area II.

In block222, referring toFIGS.10to11, a metal material26is infilled into the space between the tube10and the bushing30, and between the tube10and the first mandrel41a. The metal material26is sintered to form the capillary structure20, and then the first mandrel41ais removed.

Thus, the capillary structure20is formed by a single-step sintering process, which can reduce cost. Referring toFIG.12, each of the inner diameter D1of the capillary structures20of the first area I and the inner diameter D3of the capillary structures20of the third area III is equal to the inner diameter D2of the bushing30.

In some embodiments, the bushing30may include multiple sections wrapped on the first mandrel41a. In some embodiments, a ribbon or sheet of metal may also be wound on the surface of the first mandrel41a, thereby forming an annular bushing30.

In some embodiments, the heat pipe100may further be bent, squashed, or rounded according to actual requirements.

In some embodiments, after the heat pipe100is formed, the heat pipe100can further be tested in order to remove defects. For example, the test can include heating aging test, water bath test, heat dissipation efficiency test, appearance test, etc.

Referring toFIG.16, a device200is provided. The device200may be a mobile phone, a computer, a camera, etc., or may be other mechanical devices with a heat-generating characteristic.

The device200comprises a heat dissipation assembly210, a heat-generating element220, and a heat pipe100. The heat pipe100is connected to the heat-generating element220and the heat dissipation assembly210. The heat-generating element220generates heat. The heat is transferred to the heat dissipation assembly210through the heat dissipation effect of the heat pipe100to further quickly dissipate the heat, so that the device200is maintained in a suitable temperature range.

The heating-generating element220could be a battery, a CPU, or the like.

The heat pipe100is provided with a bushing30in the adiabatic section12. When the working fluid50in the heat pipe100is not completely vaporized, the non-vaporized working fluid50and the vaporized gas pass through the bushing30. The liquefied fluid in the condensation section13flows through the capillary structure20disposed outside the bushing30. Therefore, the bushing30insulates the flow path of the non-vaporized working fluid50and the liquefied working fluid50, the bushing30prevents the non-vaporized working fluid50and the liquefied working fluid50from mixing and colliding with each other. and noise is thus avoided.