Blank for a heat transfer device and method of manufacturing a heat transfer device

Abstract

A blank (100) for a heat transfer device (102) comprises a steam chamber (106) and a feed tube (108), wherein the steam chamber (106) is enclosed by a body (104) of the heat transfer device (102), and the feed tube (108) is connected to the steam chamber (106), wherein a portion of the feed tube (108) protruding from the body (104) has at least one unsealed sealing area (112), the unsealed sealing area (112) having an oblong flow area (200), wherein the width of the feed tube (108) exceeds the height of the feed tube (108).

Description

Technical Field

[0001] The invention relates to a blank for a heat transfer device and a method for producing a heat transfer device. Background Art

[0002] The heat transfer device may be a phase change device. The heat transfer device may maintain a fluid within a chamber of the heat transfer device in a vacuum. The vacuum affects the phase change temperature of the fluid. The evaporation temperature of the fluid may be defined by the heat load, the ambient air temperature, and the amount of phase change fluid.

[0003] The chamber can be filled with a fluid, evacuated and sealed from the surrounding atmosphere. In order to seal the chamber, a feed pipe leading to the chamber can be welded closed. Summary of the invention

[0004] It is an object of the present invention to provide an improved blank for a heat transfer device.

[0005] The present invention relates to a blank for a heat transfer device, which blank includes a steam chamber and a feed tube, wherein the steam chamber is enclosed by the main body of the heat transfer device, and the feed tube is connected to the steam chamber, wherein the part of the feed tube protruding from the main body has at least one unsealed sealing area, and the unsealed sealing area has an oblong flow area, wherein the width of the feed tube exceeds the height of the feed tube.

[0006] The present invention also relates to a method for producing a heat transfer device, which includes: supplying the blank, injecting the working fluid into the steam chamber through the unsealed sealing area and the feed pipe, evacuating the steam chamber through the unsealed sealing area and the feed pipe, flattening the unsealed sealing area, wherein the oblong flow area of ​​the unsealed sealing area is blocked into the planar shape of the closed sealing area, and cold welding the closed sealing area to produce a sealed sealing area.

[0007] A heat transfer device can use two continuous phase changes of a fluid enclosed in a vapor chamber of the heat transfer device to transfer thermal energy through the device. The first phase change can be the evaporation of the fluid from a liquid to a vapor. The second phase change can be the condensation of the fluid from the vapor to a liquid. The vacuum within the vapor chamber can affect the temperature of the phase change.

[0008] The blank may be referred to as an unfinished heat transfer device.The blank may also be free of fluid within the steam chamber, and the steam chamber may be open to the surrounding atmosphere such that the pressure inside the steam chamber may equal the pressure outside the steam chamber.

[0009] A heat source may define a hot side of a heat transfer device. A heat source may be thermally connected to the hot side. A heat source may provide thermal energy. A heat sink may define a cold side of a heat transfer device. A heat sink may be thermally connected to the cold side. A heat sink may absorb thermal energy. For example, a heat source may be a microprocessor. For example, a heat sink may be a heat dissipator.

[0010] Evaporation occurs on the hot side. Ideally, the heat energy from the heat source is absorbed isothermally by the enthalpy of evaporation and causes the first phase change from liquid to vapor. The vapor transports the heat energy to the cold side through the vapor chamber.

[0011] Condensation of the vapor occurs on the cold side. Ideally, the enthalpy of condensation is released isothermally to the heat sink and causes a second phase change from vapor back to liquid. The liquid moves back to the hot side through the vapor chamber.

[0012] The movement of the different phases of the fluid is driven by the concentration gradient within the vapor chamber. Vapor is produced on the hot side and disappears on the cold side. Liquid is produced on the cold side and disappears on the hot side. Liquid flow may be affected by gravity.

[0013] A wick within the vapor chamber can promote movement of liquid back to the hot side via capillary forces. Capillary forces can overcome gravity to a certain extent. Capillary forces can be caused by fluid being attracted to the pores in the wick.

[0014] The feed tube can be a device that transforms the blank into a functioning heat transfer device. Fluid can be filled into the steam chamber through the feed tube. The pressure in the steam chamber can be reduced by sucking gas out of the steam chamber through the feed tube. The set pressure can be separated from the surrounding atmosphere by closing or sealing the feed tube. The feed tube can be closed by squeezing the feed tube into a flat shape. During the extrusion process, the material of the feed tube is bent and plastically deformed. The stress in the material can depend on the amount of bending and deformation.

[0015] Sealing can occur in a predetermined sealing area of ​​the feed tube. The sealing area in an unsealed state can provide the necessary flow area to inject fluid into the steam chamber and extract gas from the steam chamber. The sealing area can be compressed to close the flow area to zero.

[0016] The unsealed sealing area may have an oblong flow area with a special flattened shape. The special shape may require a limited amount of deformation until the flow area is zero. Since the deformation is limited, the tension and stress in the material of the sealing area are also limited. The flattened shape may reduce the displacement of the material during compression of the oblong flow area. Due to the flattened shape, the strain hardening of the material may be limited. Cracks may be avoided.

[0017] The flow area of ​​the unsealed seal can be approximately equal to the flow area of ​​the feed tube except the sealing area. The oblong flat shape can have an aspect ratio between 0.1 and 0.9. For example, the oblong flow area can be a rectangle, a diamond or a stretched polygon.

[0018] The cold welding process can fuse materials together in a sealed area without melting the materials. The cold welding process can use pressure and controlled heating of the materials to bond the materials at a molecular or atomic level. During the cold welding process, the contacting surfaces can be ground against each other. Since the ignition temperature of the flammable fluid is not reached during the cold welding process, flammable fluids can be used in the steam chamber.

[0019] In one embodiment, the fluid is degassed through the unsealed sealing area and the feed tube before cold welding. The fluid can be degassed by heating. The entire body of the heat transfer device can be heated. The generated steam and escaping gases can be discharged through the feed tube. The steam chamber can be evacuated before degassing. The feed tube can also be longer and have more than one sealing area. The outer sealing area can be sealed before degassing. Escaping gases can be trapped in the feed tube. The inner sealing area can be sealed at the end of degassing. Escaping gases may be trapped in the feed tube.

[0020] In one embodiment, an ultrasonic welding process is used to cold weld the closed sealing area. The ultrasonic welding process uses pressure and friction caused by ultrasonic vibrations to connect two contacting surfaces. During the ultrasonic welding process, the sealing area can be compressed between the anvil and the vibrating sonotrode. Before the cold welding process begins, the anvil and sonotrode can squeeze the sealing area flat. Alternatively, a friction welding process can be used.

[0021] In one embodiment, the oblong flow area of ​​the unsealed sealing area is bi-concave. The bi-concave sealing area can have sharp or pointed edges. Stress during extrusion can be minimized in the edge area. For example, the bi-concave shape can be formed by connecting two annular portions. The bi-concave shape can also be referred to as a lance with tapered tips at both ends.

[0022] In an alternative embodiment, the oblong flow area of ​​the unsealed sealing area is elliptical. The elliptical sealing area has rounded edges. The ellipse can be easily shaped.

[0023] In one embodiment, the feed pipe has a prismatic partition with a constant flow area. The prismatic partition can have a circular, rectangular or hexagonal flow area. The prismatic partition can have an oblong flow area of ​​the sealing area. The prismatic partition can be arranged on the inside or outside of the body. The height of the prismatic partition can be equal to the height of the steam chamber.

[0024] In one embodiment, the feed tube has a tapered divider with a varying shape. The tapered divider may be arranged on the inside or outside of the body. The varying shape of the tapered divider may transition from one adjacent shape to another adjacent shape. The tapered divider may allow for a soft transition between different shapes. The tapered divider may allow for favorable fluid dynamics during injection and vacuuming. The tapered divider may be a transition to the sealing area.

[0025] In one embodiment, the portion of the feed tube protruding from the body has at least one other unsealed sealing area having an oblong flow area, wherein the width of the feed tube exceeds the height of the feed tube. The sealing areas can be shaped identically. If one sealed sealing area fails, the other may still be leakproof. Two or more sealing areas can create a more secure seal.

[0026] In one embodiment, at least one partition of the feed tube is arranged between the sealing areas. The sealing areas may be separated by a distance. In this way, a failure in one sealing area does not affect another sealing area. The distance may prevent the propagation of cracks. A sharp transition or a soft transition may be used between the partition and the sealing area.

[0027] In one embodiment, the body and feed tube are selectively sintered from loose metal powder particles by additive manufacturing. By additive manufacturing, a favorable shape can be produced. Unused metal powder particles can be shaken out of the steam chamber through the feed tube and the unsealed sealing area. The selectively sintered material can have favorable thermal properties, but may be brittle. Cold welding of the sintered material can be promoted by the oblong flow area of ​​the sealing area. The metal material can be, for example, aluminum material. The metal material can be an alloy. The body can be sintered according to a CAD model. The body can be irregularly shaped.

[0028] In one embodiment, the portion of the feed tube protruding from the main body is sintered integrally with the main body. In this way, only one integral piece can be taken out from the loose metal powder particles.

[0029] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The subject matter of the invention will be explained in more detail hereinafter with reference to exemplary embodiments shown in the drawings.

[0031] Figure 1 schematically illustrates a blank according to one embodiment;

[0032] Figure 2 shows a feed tube with a sealing area according to one embodiment; and

[0033] Figure 3 A method for manufacturing a Figure 1 Flow chart of a method of heat transfer apparatus.

[0034] The reference symbols used in the drawings and their meanings are listed in summary form in the reference symbol list. In principle, identical components are provided with the same reference numerals in the figures. DETAILED DESCRIPTION

[0035] Figure 1 A blank 100 according to one embodiment is schematically illustrated. The blank 100 is an unfinished heat transfer device 102. The heat transfer device is a phase change heat transfer device 102. The heat transfer device has a fluid-proof body 104. The body 104 encloses a steam chamber 106. A feed tube 108 is connected to the steam chamber 106. The feed tube 108 partially protrudes from the body 104. Since the blank 100 is not yet a functional phase change heat transfer device 102, the feed tube 108 has an open end 110 protruding from the body 104. An unsealed sealing area 112 is arranged at the open end 110. The unsealed sealing area 112 has an oblong flow area to facilitate flattening the feed tube 108 before cold welding the compression sealing area 112.

[0036] In one embodiment, the unsealed seal area 112 has an elliptical flow area.

[0037] In one embodiment, the feed tube 108 has a tapered partition 114 disposed between the sealing area 112 and the body 104. In the tapered partition 114, the shape of the feed tube 108 gradually changes along the length of the tapered partition 114. Here, the shape changes from a cylindrical flow area to an oblong flow area of ​​the sealing area 112.

[0038] In one embodiment, the flow area of ​​the feed tube 108 remains constant throughout its length.

[0039] In one embodiment, the feed tube 108 has two prismatic partitions 116, 118, which are arranged on either side of the conical partition 114. The shape of the prismatic partitions 116, 118 is constant along the length of the prismatic partitions 116, 118. The first prismatic partition 116 is arranged inside the wall of the body 104 and connects the conical partition 114 to the steam chamber 106. The second prismatic partition 118 forms the sealing area 112 and has an oblong flow area.

[0040] To produce the heat transfer device 102, the steam chamber 106 is first evacuated via the feed tube 108 and then partially filled with a fluid via the feed tube 108. Finally, the feed tube 108 is closed to maintain the vacuum inside the steam chamber 106. Due to the vacuum, the fluid is in a saturated state, where a certain portion of the fluid is liquid and the remaining volume is occupied by the gas phase of the same fluid. The negative pressure generated is set by the temperature of the fluid inside the steam chamber. During the filling operation, the temperature is essentially the ambient temperature. Then, during working conditions, the internal fluid pressure and temperature increase due to the heat applied on the hot side.

[0041] The evaporation temperature of the fluid is set by the negative pressure inside the shell. The negative pressure also determines the condensation temperature of the fluid. The evaporation temperature and the condensation temperature are essentially equal. In this way, as long as there is liquid fluid available on the hot side, the heat energy from the heat source can be transferred to the heat sink at the evaporation temperature.

[0042] To close the open end 110 of the feed tube 108, the unsealed sealing area 112 is compressed in a mold. After compression, the inner surfaces of the sealing area 112 are in close contact along the length of the sealing area. To secure the now closed end, the sealing area 112 is cold welded and the inner surfaces are fused together.

[0043] Figure 2 FIG. 1 shows a schematic diagram of a device having an unsealed sealing area 112 according to one embodiment. Figure 1 The feed tube 108 of FIG. 10 is a feed tube 108. The sealing area 112 has a double concave oblong flow area 200. The oblong flow area 200 has a major axis and a minor axis. The aspect ratio of the minor axis to the major axis is 0.1 to 0.9. Here, the major axis is about four times longer than the minor axis, and the aspect ratio is 1:4. The flow area 200 has sharp edges at the ends of the major axis.

[0044] In one embodiment, the feed tube 108 has three partitions 114, 116, 118. The sealing area 112 is arranged at the open end 110 of the feed tube 108 and is composed of a prismatic partition 118. The conical partition 114 is arranged between the two prismatic partitions 116, 118 and deforms the double concave oblong flow area 200 of the unsealed sealing area 112 into the circular flow area of ​​the other prismatic partition 116.

[0045] Figure 3 shows the method for making Figure 1 A flow chart of a method of heat transfer device 102 is shown.

[0046] In step S10 , a blank 100 for a heat transfer device 102 is provided.

[0047] In step S12 , the working fluid is injected into the steam chamber. The working fluid is injected through the unsealed sealing area 112 and the feed pipe 108 .

[0048] In step S14 , the steam chamber 106 is evacuated. The steam chamber 106 is evacuated through the unsealed sealing area 112 and the feed pipe 108 .

[0049] In step S16 , the unsealed sealing area 112 is squeezed to be flat, so that the oblong flow area 200 of the unsealed sealing area 112 is blocked into the flat shape of the closed sealing area 112 .

[0050] In step S18 , the closed sealing area 112 is cold welded to form a sealed sealing area 112 .

[0051] In other words, a variable area feed pipe for a steam chamber is provided.

[0052] A novel design of a feed tube for a steam chamber is disclosed, which has a variable cross section along the tube. In this way, a more reliable seal of the feed tube is achieved by reducing the stress on the inside of the tube wall during the deformation required for the sealing process. The novel design enables the use of cold welding to seal a steam chamber filled with a flammable fluid.

[0053] Conventional vapor chambers are made of copper, which is made highly ductile through a diffusion bonding process used during assembly.

[0054] To produce heat transfer devices, the fluid filling process includes liquid injection, vacuuming, degassing, and head welding. The working fluid can be deionized water. During the vacuuming process, most of the air in the steam chamber is vacuumed with a vacuum pump. Then, during the degassing process, additional air is removed by boiling. By heating the bottom of the steam chamber, the non-condensable gases in the tube are forced to accumulate in the upper part of the feed tube, and then this part of the tube can be cut off to further increase the vacuum. Finally, during the head welding process, the end of the feed tube is welded closed to achieve a stable environment in the steam chamber.

[0055] If the working fluid is not water, it is not possible to weld the head of the feed pipe due to safety issues. For example, if the steam chamber is made of aluminum, water cannot be used due to corrosion, and acetone or hydrofluoric fluids can alternatively be used. However, acetone is flammable, and hydrofluoric fluids may be flammable or decompose into toxic or corrosive byproducts under the intense heat generated during welding. In this case, a cold welding process can be used.

[0056] Cold welding is a solid-state welding process in which the joint is made at the interface of the two parts to be welded without melting / heating. Unlike fusion welding processes, there is no liquid or molten phase in the joint. For example, ultrasonic welding is a cold welding process. However, since these processes usually involve mechanical flattening of the feed tube, ductile materials are usually required to obtain a reliable seal. With non-ductile materials, cracks may be generated in the tube wall during the flattening process and jeopardize the seal.

[0057] Additive manufacturing can produce low ductility parts, which can be annealed at high temperatures to obtain sufficient ductility. However, even after this heat treatment, some alloys used with additive manufacturing processes will still not have sufficient ductility. This limitation of low ductility alloys can be overcome by the existing feed tube design described here.

[0058] In one embodiment, the fluid feed tube to the steam chamber has a different cross-section at each end.

[0059] In one embodiment, the cross-section of the end connected to the steam chamber has a larger aspect ratio (aspect ratio = d min / d max ).

[0060] In one embodiment, the cross section of the end connected to the steam chamber is substantially circular, and the end to be sealed has an extruded cross section. For example, the extruded cross section can be formed by two arcs.

[0061] In one embodiment, the tube may be decomposed into at least three sub-sections.

[0062] In one embodiment, the portion after the end connected to the steam chamber is a rectilinear sub-portion with a constant cross section.

[0063] In one embodiment, the portion before the end to be sealed is a rectilinear sub-portion with a constant cross section, but which is different from the end connected to the steam chamber.

[0064] In one embodiment, the variable cross-section sub-portion is arranged between the linear sub-portions of constant cross-section. The variable cross-section sub-portion transitions from the cross-section of a first linear sub-portion to another linear sub-portion. The path of the transition can be a straight line or a curve.

[0065] In one embodiment, the feed tube has more than three variable subsections for double sealing.

[0066] In one embodiment, the second linear sub-portion has an elongated shape (x>y), such as an ellipse, rectangle, diamond, stretched polygon or other shape. Therefore, when a cold welding process is used, the relative displacement in such an elongated cross-section is reduced, which allows the use of less ductile alloys.

[0067] In one embodiment, the feed tube is subdivided into more than three subsections. For example, the filling process may rely on sealing in two different cross sections to minimize the risk of trapping non-condensable gases in the steam chamber. In this case, the filling tube may have multiple (including two) subsections with elongated cross sections for sealing.

[0068] Although the invention has been described and illustrated in detail in the drawings and the foregoing description, such description and illustration should be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments may be understood and effected by a person skilled in the art and by a person practicing the claimed invention by studying the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or controller or other unit may perform the functions of several items recited in the claims. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

[0069] Reference Symbols List

[0070] 100 blanks

[0071] 102Heat transfer equipment

[0072] 104 Main Body

[0073] 106 Steam Room

[0074] 108 Feed pipe

[0075] 110 Open end

[0076] 112 Sealed Area

[0077] 114 Conical separator

[0078] 116 prism-shaped partition

[0079] 118 prism-shaped partition

[0080] 200 flow area

Claims

1. A blank (100) for a heat transfer device (102), comprising: a vapor chamber (106) enclosed by the body (104) of the heat transfer device (102), and a feed pipe (108) connected to the steam chamber (106), wherein a portion of the feed tube (108) extending from the body (104) has at least one unsealed sealing area (112), the unsealed sealing area having an oblong flow area (200), the cross section of the oblong flow area (200) having a major axis and a minor axis; wherein the feed tube has a tapered partition disposed between the at least one sealing area and the body, wherein the shape of the tapered divider changes from a cylindrical flow region to an oblong flow region along the length of the tapered divider, and The width of the feed pipe (108) exceeds the height of the feed pipe (108).

2. The blank (100) according to claim 1, The cross-section of the oblong flow region (200) of the unsealed sealing region (112) is bi-concave.

3. The blank (100) according to claim 1, The cross-section of the oblong flow region (200) of the unsealed sealing area (112) is elliptical.

4. The blank (100) according to claim 1, The feed tube (108) has prismatic partitions (116, 118) having a constant flow area (200).

5. The blank (100) according to any one of claims 1 to 4, The portion of the feed tube (108) extending from the main body (104) has at least one other unsealed sealing area, the other unsealed sealing area having an oblong flow area (200), wherein the width of the feed tube (108) exceeds the height of the feed tube (108).

6. The blank (100) according to claim 5, At least one partition of the feed tube (108) is arranged between the sealing area (112) and the other unsealed sealing area.

7. The blank (100) according to any one of claims 1 to 4, The body (104) and the feed tube (108) are selectively sintered from loose metal powder particles by additive manufacturing.

8. The blank (100) according to claim 7, The portion of the feed tube (108) protruding from the main body (104) is sintered integrally with the main body (104).

9. A method of producing a heat transfer device (102), the method comprising: A blank (100) according to any one of claims 1 to 8 is provided, injecting a working fluid into the steam chamber (106) through the unsealed sealing area (112) and the feed pipe (108), The steam chamber (106) is evacuated through the unsealed sealing area (112) and the feed tube (108), squeezing the unsealed sealing area (112) into a flat shape, wherein the oblong flow area (200) of the unsealed sealing area (112) is blocked into a flat shape of the closed sealing area (112), and The closed sealing area (112) is cold welded to produce a sealed sealing area (112).

10. The method according to claim 9, The fluid is degassed through the unsealed sealing area (112) and the feed tube (108) prior to cold welding.

11. The method according to any one of claims 9 to 10, The closed sealing area (112) is cold welded using an ultrasonic welding process.

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