CN116601449A - Flexible heat pipe - Google Patents

Abstract

A heat pipe (100, 200, 300, 400, 500, 600, 700) having an envelope (102, 202, 302) with a working fluid, a wick (108, 206, 504) inner layer, and a flexible bellows (104) is provided. The envelope has a condenser end, an evaporator end, and an insulating portion between the condenser end and the evaporator end. The core inner layer is disposed on an inner surface of the envelope for transporting condensed working fluid from the condenser end to the evaporator end. The insulating portion comprises perforated and compressed areas (106, 204, 502) of the wall of the envelope forming a passage for the vapor, in which compressed areas the wall of the envelope is offset towards the central axis of the envelope. The flexible bellows covers the compression zone and defines a channel (112) for the steam, the ends of the flexible bellows being sealed to the walls of the envelope outside the perforations.

Description

Flexible heat pipe

Technical Field

The present application relates generally to heat pipes, and more particularly to heat pipes and methods of manufacturing heat pipes.

Background

A heat pipe is a special device that can transfer heat over long distances due to a combination of the following processes: (a) evaporation of the liquid phase of the internal working medium from the porous structure (core), (b) transport of the gaseous phase of the internal medium through the vapor channels, (c) condensation of the gaseous phase of the internal medium on the core, and (d) transport of the liquid phase of the internal medium from the condensation zone to the evaporation zone through the core in a closed loop inside the sealed envelope (housing).

In the known method, the different fields of application of the heat pipe assume that there is no strong mechanical interconnection between the cooler block and the heater block. In this case, for example, the cooler block may be moved in a space with respect to the heater block. In the existing heat pipe, one end of the heat pipe is fixed, and the other end moves + -1.5 millimeters (mm) in the vertical direction. To avoid damaging the heat pipe or separating the heat pipe from the cooler block and the heater block, the heat pipe should be flexible, i.e. the reaction force from either the heater block or the cooler block to the heat pipe should be low, e.g. less than 2.5 newton units (N). The existing heat pipe is a flat heat pipe with a reaction force of about 25N to 50N during this movement, which is far from the low value (e.g. 2.5N) required for flexibility.

Several known solutions solve this problem by attaching a bellows-shaped portion to the heat pipe. However, the known solutions have problems for manufacturing heat pipes in mass production mode. In addition, the mesh on the curved region of the heat pipe is not attached to the substrate (wall), which can result in low capillary forces. The known solutions also use a wick located near the outer wall rather than in the center of the heat pipe, which can lead to high elongation, high stress and ultimately damage the heat pipe. The known solutions also propose adding springs in the heat pipe, but do not completely solve the problem of destruction, and also occupy internal space, resulting in low thermal performance. The known solutions also present complex designs with many components that need to be assembled during the manufacturing process. Therefore, these designs are not suitable for mass production. Furthermore, known solutions propose to bring the wick close to the flexible wall in the heat pipe, which results in the wick layer being away from the neutral plane (zero stress region near the axis of the heat pipe) and becoming elongated during bending, which results in an increase of the reaction force and possibly damage to the wick.

Accordingly, there is a need to address the above-described technical problems in existing systems or techniques to create a heat pipe that is suitable for mass production and has reduced reaction forces and thus flexibility.

Disclosure of Invention

It is an object of the present application to provide a heat pipe and a method of manufacturing a heat pipe, which is suitable for mass production and has reduced reaction force from a heating block or a cooling block, thereby having flexibility.

This object is achieved by the features of the independent claims. Further, implementations are evident in the dependent claims, the description and the drawings.

The present application provides a heat pipe with a small reaction force for mass production and a method of manufacturing the same.

According to a first aspect, a heat pipe is provided. The heat pipe includes an envelope with a working fluid, a core inner layer, and a flexible bellows. The envelope has a condenser end, an evaporator end, and an insulating portion between the condenser end and the evaporator end. The core inner layer is disposed on an inner surface of the envelope for transporting condensed working fluid from the condenser end to the evaporator end. The insulating portion comprises a perforated and compressed area of the wall of the envelope forming a passage for the vapor, in which compressed area the wall of the envelope is offset towards the central axis of the envelope. The flexible bellows covers the compression zone and defines a passage for the steam, the ends of the flexible bellows being sealed to the walls of the envelope outside the perforations.

The heat pipe according to the present application reduces a reaction force as compared with the conventional heat pipe, thereby having flexibility. For example, in one implementation, a reaction force of less than 2.5 newton units (N) has been achieved. In addition, the heat pipe is simple in design and suitable for mass production. Meanwhile, the thermal performance of the heat pipe is equivalent to that of a traditional inflexible heat pipe produced in a large scale, which indicates that the design is simple, the flexibility is strong, and the thermal performance has no defects.

In a first possible implementation, the perforation of the wall of the envelope comprises a longitudinal through hole made from two opposite sides of the envelope.

In a second possible implementation, the compression zone comprises a planar channel for conveying the condensed working fluid, the planar channel having a conical portion at each end.

In a third possible implementation, the planar channel is arranged substantially in the plane of the central axis of the envelope.

In a fourth possible implementation, the flexible bellows has an elliptical cross section.

In a fifth possible implementation, the compression zone is provided with a fixing device provided on the wall of the envelope, which is offset towards the central axis of the envelope.

In a sixth possible implementation, the fixing means is one of a wire winding, a foil wrapping and a contact resistance weld.

In a seventh possible implementation, the perforation of the wall of the envelope comprises one or more additional through holes forming the channel of the steam.

In an eighth possible implementation, the perforations of the wall of the envelope extend to a major portion of the circumference of the envelope.

In a ninth possible implementation, the wall and/or core of the envelope in the compression zone is provided with one or more transverse grooves and/or through holes.

In a tenth possible implementation, a core outer layer is arranged on the inner surface of the flexible bellows, the core outer layer being in communication with the core inner layer.

In an eleventh possible implementation, a second core outer layer is arranged on the outer surface of the envelope in the compression region, the second core outer layer being in communication with the core inner layer.

In a twelfth possible implementation, the condenser end to the evaporator end is flat.

In a thirteenth possible implementation, the outer surface of the flexible bellows is provided with a layer of a low thermal conductivity material.

In a fourteenth possible implementation, the core includes one or more of sintered particles, mesh, fibers, and grooves.

According to a second aspect, a method of manufacturing a heat pipe is provided. The method includes providing an envelope having a condenser end, an evaporator end, and an insulating portion therebetween. The method includes disposing a core layer on an inner surface of the envelope for transporting condensed working fluid from the condenser end to the evaporator end. The method includes perforating a wall of the envelope in the insulating portion to form a passage for vapor. The method includes offsetting the wall of the envelope toward a central axis of the envelope to define a compression region in the insulating portion. The method includes covering the compression region with a flexible bellows to define a passage for the vapor, an end of the flexible bellows being sealed to a wall of the envelope outside the perforation. The method includes filling the envelope with the working fluid. The method includes sealing the condenser end and the evaporator end of the envelope.

According to a third aspect, a method of manufacturing a heat pipe is provided. The method includes providing an envelope having a condenser end, an evaporator end, and an insulating portion therebetween. The method includes perforating a wall of the envelope in the insulating portion to form a passage for vapor. The method includes disposing a core layer on an inner surface of the envelope for transporting condensed working fluid from the condenser end to the evaporator end. The method includes offsetting the wall of the envelope toward a central axis of the envelope to define a compression region in the insulating portion. The method includes covering the compression region with a flexible bellows to define a passage for the vapor, an end of the flexible bellows being sealed to a wall of the envelope outside the perforation. The method includes filling the envelope with the working fluid. The method includes sealing the condenser end and the evaporator end of the envelope.

According to a fourth aspect, a method of manufacturing a heat pipe is provided. The method includes providing an envelope having a condenser end, an evaporator end, and an insulating portion therebetween. The method includes perforating a wall of the envelope in the insulating portion to form a passage for vapor. The method includes offsetting the wall of the envelope toward a central axis of the envelope to define a compression region in the insulating portion. The method includes disposing a core layer on an inner surface of the envelope for transporting condensed working fluid from the condenser end to the evaporator end. The method includes covering the compression region with a flexible bellows to define a passage for the vapor, an end of the flexible bellows being sealed to a wall of the envelope outside the perforation. The method includes filling the envelope with the working fluid. The method includes sealing the condenser end and the evaporator end of the envelope.

The technical problem in the prior art is solved in that the heat pipe should be flexible, i.e. the reaction force from either the heater block or the cooler block to the heat pipe should be reduced, e.g. below 2.5N, in order to avoid damaging the heat pipe or to avoid separation of the heat pipe from the cooler block and the heater block.

Thus, unlike the prior art, according to the heat pipe and the method of manufacturing the heat pipe, the heat pipe has flexibility due to a reduced reaction force compared to the conventional heat pipe. The heat pipe is simple in design and suitable for mass production. Meanwhile, the thermal performance of the heat pipe is equivalent to that of a traditional inflexible heat pipe produced in a large scale, which indicates that the design is simple, the flexibility is strong, and the thermal performance has no defects.

These and other aspects of the application will be apparent from one or more implementations described below.

Drawings

Implementations of the application will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1A illustrates a heat pipe with flexible bellows in accordance with an implementation of the present application;

FIG. 1B illustrates an exemplary view of the heat pipe of FIG. 1A with flexible bellows prior to a manufacturing process of an implementation of the present application;

FIG. 1C illustrates a perspective view of the heat pipe of FIG. 1A in accordance with an implementation of the present application;

FIG. 1D illustrates a longitudinal cross-sectional view of the heat pipe of FIG. 1A in accordance with an implementation of the present application;

FIG. 1E illustrates a cross-sectional view of the heat pipe of FIG. 1A in accordance with an implementation of the present application;

FIG. 2 illustrates a heat pipe having one or more wires forming a connection between one or more compression walls in accordance with an implementation of the present application;

FIG. 3 illustrates a heat pipe with additional through holes for vapor flow in accordance with an implementation of the present application;

FIG. 4 illustrates a heat pipe with additional holes for vapor flow in accordance with an implementation of the present application;

FIG. 5 illustrates a heat pipe with a cut upper wall of an implementation of the present application;

FIG. 6 illustrates a heat pipe with additional vapor holes in the wall of the heat pipe in accordance with an implementation of the present application;

FIG. 7 illustrates a heat pipe of an implementation of the present application;

FIG. 8 illustrates a heat pipe mechanical test scheme of an implementation of the present application;

FIG. 9 is a graph showing the mechanical response of cyclic loading of a heat pipe over time for an implementation of the present application;

FIGS. 10A through 10B are flow diagrams of a first method of manufacturing a heat pipe in accordance with an implementation of the present application;

FIGS. 11A through 11B are flow diagrams of a second method of manufacturing a heat pipe in accordance with an implementation of the present application; and is also provided with

Fig. 12A through 12B are flowcharts of a third method of manufacturing a heat pipe in accordance with an implementation of the present application.

Detailed Description

Implementations of the present application provide a flexible heat pipe with a small reaction force for mass production.

In order that those skilled in the art will more readily understand the solution of the present application, the following implementation of the application is described with reference to the accompanying drawings.

The terms first, second, third and fourth (if any) in the description of the application, in the claims and in the above-described figures, are used for distinguishing between similar objects and not necessarily for describing a particular sequence or order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the implementations of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to encompass non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to the particular steps or elements recited, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

FIG. 1A illustrates a heat pipe 100 with flexible bellows 104 in accordance with an implementation of the present application. The heat pipe 100 includes an envelope 102 with a working fluid, an inner layer of a wick 108, and a flexible bellows 104. The envelope 102 has a condenser end, an evaporator end, and an insulating portion between the condenser end and the evaporator end. The core 108 inner layer is disposed on the inner surface of the envelope 102 for transporting condensed working fluid from the condenser end to the evaporator end. The insulating portion comprises a perforated and compressed area 106 of the wall of the envelope 102 forming a channel for the vapour, in which compressed area the wall of the envelope 102 is offset towards the central axis of the envelope 102. The flexible bellows 104 covers the compression region 106 and defines a passage 112 for the vapor, the ends of the flexible bellows 104 being sealed to the wall of the envelope 102 outside the perforation. The perforations of the wall of the envelope 102 optionally comprise longitudinal through holes 110 made from two opposite sides of the envelope 102. The jacket 102 may be a copper tube. The core 108 may be a sintered core or a sintered porous structure comprising sintered powder, a reticulated core, or one or more flutes. Optionally, the core 108 includes one or more of sintered particles, mesh, fibers, and grooves. The core 108 is optionally located on the inner surface of the envelope 102 and on two opposite sides of the intermediate region of the envelope 102 comprising the longitudinal through hole 110. The remaining regions of the intermediate region are pressed together in such a way that a portion of the wall and one or more layers of the core 108 form a flat plate near the axis of the heat pipe 100. Optionally, a felt, one or more grooves, a non-sintered mesh, or a plurality of felts are used to sinter the porous structure.

The envelope 102 has a structure for liquid/fluid circulation. The region of the heat pipe 100 having the longitudinal through-holes 110 is encapsulated to the flexible bellows 104. In the region of the heat pipe 100, the open side of the flexible bellows 104, together with the cuff 102, undergoes a welding procedure on the region without the longitudinal through-holes 110. The welding procedure may be performed in such a way that a channel 112 is formed between the inner surface of the flexible bellows 104 and the region of the cuff 102 having the longitudinal through hole 110.

Referring to fig. 1A, fig. 1B shows an exemplary view 101 of a heat pipe 100 with flexible bellows 104 during a manufacturing process of an implementation of the present application. The heat pipe 100 includes an envelope 102, a flexible bellows 104, a compression region, an inner layer of a wick 108, and a longitudinal through-hole 110. For manufacturing, a round heat pipe with the envelope 102 as copper wall and the core 108 as a sintered core layer is used. Optionally, a core 108 outer layer is disposed on the inner surface of the flexible bellows 104, the core outer layer in communication with the core 108 inner layer. Optionally, a second core 108 outer layer is disposed on the outer surface of the cuff 102 in the compression region 106, the second core outer layer in communication with the core 108 inner layer. Optionally, the outer surface of the flexible bellows 104 is provided with a layer of low thermal conductivity material. Optionally, the flexible bellows 104 is of a material different from the material of the wall. Two holes are formed on both sides of the middle region of the envelope 102, and the remaining compressed region 106 or wall is pressed together in the middle region in such a way that a portion of the wall and one or more layers of the core 108 become flat plates near the axis of the heat pipe 100. The remaining walls of the envelope 102 are not fully compressed such that the open pores have the function of longitudinal through-holes 110 for circulating steam between the ends of the heat pipe 100 and the volume of the flexible bellows 104. The flexible bellows 104 may be moved to an intermediate region of the heat pipe 100 to cover the region of the heat pipe 100 having the longitudinal through-holes 110 and the compressed region 106. Compression region 106 may include planar channels for transporting condensed working fluid, each of the planar channels having a tapered portion at each end. The planar channel may be disposed in the plane of the central axis of the cuff 102. The plane may be a neutral plane. The wick 108 of the heat pipe 100 is located in the middle of the cross section of the heat pipe 100 near the neutral plane where stress is minimal during bending. Therefore, the deformation of the core 108 and the remainder of the wall is very small, and the stress and reaction forces are also significantly reduced, thereby providing flexibility to the heat pipe 100. The ends of the flexible bellows 104 are welded to the cuff 102. Thereafter, the condenser end to the evaporator end is flat. The walls of the envelope 102 and/or the core 108 layer in the compression region 106 may also be provided with one or more lateral grooves and/or through holes to further reduce the reaction force and increase the flexibility of the heat pipe 100.

The heat pipe 100 may be manufactured by: (i) Producing a round heat pipe having a wick 108 as a sintered wick; (ii) One or more technical operations are performed, such as (a) cutting longitudinal through holes 110 on the sides of the heat pipe 100 according to the length of the flexible region, (b) pressing the two walls and wick 108 together to the axis of the heat pipe 100, (c) inserting the heat pipe 100 into the flexible bellows 104, (d) welding the flexible bellows 104 to the heat pipe 100, and (e) filling the heat pipe 100 with water. The one or more technical operations are suitable for mass production mode production. The cost of heat pipe 100 is increased by a negligible amount compared to a round heat pipe. Since the flexible bellows 104 needs to be connected to the core 108, any size of waveform can be selected and bending of the flexible bellows 104 is accomplished with minimal force.

Optionally, the flexible bellows 104 has an elliptical cross-section. The flexible bellows 104 may be other shapes, such as a flat shape. Alternatively, the housing of the heat pipe 100 outside of the flexible bellows 104 may be flat, circular, or any other shape.

Referring to fig. 1A and 1B, fig. 1C shows a perspective view 103 of a heat pipe 100 of an implementation of the present application. The perspective view 103 is achieved after the manufacturing process. The perspective view 103 includes an envelope 102 and a flexible bellows 104.

Referring to fig. 1A and 1B, fig. 1D shows a longitudinal cross-sectional view 105 of a heat pipe 100 of an implementation of the present application. The longitudinal cross-sectional view 105 includes the cuff 102, the flexible bellows 104, the compression region 106, the core 108, the longitudinal through-holes 110, and the channels 112.

Referring to fig. 1A and 1B, fig. 1E illustrates a cross-sectional view 107 of a heat pipe 100 of an implementation of the present application. The cross-sectional view 107 of the heat pipe 100 includes the envelope 102, the flexible bellows 104, the compression region 106, the wick 108, and the longitudinal through-hole 110. Optionally, the diameter of the envelope 102 is changed.

FIG. 2 illustrates a heat pipe 200 having one or more wires 210 forming a connection between one or more compression walls in accordance with an implementation of the present application. The heat pipe 200 includes an envelope 202, a compressed region 204, a wick 206, a through-hole 208, and one or more wires 210. The compression region 204 or one or more compression walls are secured using one or more wires 210 of the heat pipe 200 to control the reaction force during bending. The compression zone 204 is provided with a fixation means provided on the wall of the envelope 202, which is offset towards the central axis of the envelope 202. The securing means is one of a wire wrap, a foil wrap and a contact resistance weld.

FIG. 3 illustrates a heat pipe 300 having additional through holes 304A-304N for vapor flow in accordance with an implementation of the present application. Heat pipe 300 includes an envelope 302 and additional through holes 304A-304N. The perforations in the walls of the envelope 302 include additional through holes 304A-304N that form channels for the vapor.

FIG. 4 illustrates a heat pipe 400 with additional holes 402 for vapor flow in accordance with an implementation of the present application. The heat pipe 400 includes one or more additional vapor holes 402. To achieve low reaction forces, e.g., less than 2.5N, the compression area of the envelope of the heat pipe 400 is configured to be as long as possible. In the heat pipe 400, the additional vapor holes 402 for the vapor may be configured as small as possible, but the vapor pressure drop is higher for stable operation of the heat pipe 400. To achieve stable operation of the heat pipe 400, one or more additional vapor holes 402 may be created within the compression region, as shown in fig. 3 and 4. Alternatively, the number and shape of such additional steam holes 402 may be different.

Fig. 5 shows a heat pipe 500 with a cut upper wall of an implementation of the application. Heat pipe 500 includes a compressed region 502 and a wick 504. To reduce the reaction force of the heat pipe 500, one of the remaining walls of the compressed region 502 is removed, and the thermal problem of the heat pipe 500 can be solved by optimizing the thickness and shape of the wick 504. Thus, the perforations of the walls of the envelope of the heat pipe 500 extend to a major portion of the circumference of the envelope.

Fig. 6 illustrates a heat pipe 600 of an implementation of the present application in which the walls and/or core of the envelope in the compression region are provided with lateral grooves or through holes 602 to further reduce the reaction force of the heat pipe 600 and increase its flexibility. Heat pipe 600 includes one or more lateral grooves or through holes 602.

FIG. 7 illustrates a heat pipe 700 of an implementation of the present application. Heat pipe 700 is in contact with heater 702, cooler 704, and includes one or more temperature sensors 706A-706D. Heat pipe 700 may be fabricated with a sample wall. The heater 702 and the cooler 704 may be 40 millimeters (mm) wide. Temperature sensor 706A may be placed at the surface of the envelope of heat pipe 700 where the center point of heater 702 is located, with a 20mm width on either side of the envelope. The temperature sensor 706D may be placed at the surface of the envelope where the center point of the cooler 704 is located, with a width of 20mm on either side of the envelope. Heat pipe 700 may be used for thermal testing where the wick of heat pipe 700 is sintered copper powder. For thermal testing, heat pipe 700 was configured using round heat pipes taken from a mass production factory and side holes were cut in the round heat pipes. The walls are pressed against each other and the flexible bellows of heat pipe 700 are welded. Alternatively, the walls are pressed against each other and against the flexible bellows using an adhesive method.

The thermal test of heat pipe 700 is performed after the mechanical test and the following results are recorded:

in the heating power range of 40 to 50 watts, the temperature difference between both ends of the heat pipe 700 is in the range of 1.5 ℃ to 2.5 ℃. Similar results may be obtained in mass production of heat pipe 700 where the overall dimensions of heat pipe 700 are equal. Accordingly, the thermal performance of heat pipe 700 is improved. Thermal testing has shown that heat pipe 700 has low reaction force, simple design, and is suitable for mass production. The thermal performance of flexible heat pipe 700 is the same as a non-flexible circular heat pipe.

Fig. 8 illustrates a scenario 800 of a thermal pipe mechanical test of an implementation of the application. Scheme 800 includes a grip of stretcher 802 connected to first hinge 806A and second hinge 806B that hold an envelope of a heat pipe. Scheme 800 includes a tight connection 808 that tightly secures a first end of an envelope of a heat pipe for processing at point 804A. The second end of the heat pipe is hinged at point 804B by first hinge 806A and second hinge 806B. Using scheme 800, a mechanical property test of the heat pipe is performed by measuring the mechanical reaction during 20 loading cycles, which may be performed using a stretcher and a tool.

Referring to fig. 8, fig. 9 shows a graph 900 of an implementation of the present application exhibiting a mechanical response of cyclic loading of a heat pipe over time. As shown in graph 900, the grip was cycled 1.5mm 20 times, which is the displacement of the point during the mechanical property test. The speed of movement of the grip may be less than 0.2mm per second. During cyclic loading, the reaction force of the heat pipe is recorded. During 20 loading cycles, the reaction force of the heat pipe may be below 2.5N, while the reaction force of a round heat pipe without flexible bellows is above 20N.

Fig. 10A to 10B are flowcharts of a first method of manufacturing a heat pipe according to an embodiment of the present application. At step 1002, an envelope is provided having a condenser end, an evaporator end, and an insulating portion therebetween. At step 1004, a core layer is disposed on an inner surface of the envelope for transporting the condensed working fluid from the condenser end to the evaporator end. At step 1006, the walls of the envelope in the insulating portion are perforated to form a channel for the vapor. At step 1008, the wall of the envelope is offset toward the central axis of the envelope to define a compression region in the insulating portion. At step 1010, the compressed region is covered with a flexible bellows to define a passage for vapor, an end of the flexible bellows being sealed to a wall of the envelope outside the perforation. At step 1012, the envelope is filled with a working fluid. At step 1014, the condenser and evaporator ends of the envelope are sealed.

Fig. 11A to 11B are flowcharts of a second method of manufacturing a heat pipe according to an embodiment of the present application. At step 1102, an envelope is provided having a condenser end, an evaporator end, and an insulating portion therebetween. At step 1104, the walls of the envelope in the insulating portion are perforated to form a channel for the vapor. At step 1106, a core layer is disposed on an inner surface of the envelope for transporting the condensed working fluid from the condenser end to the evaporator end. At step 1108, the wall of the envelope is offset toward the central axis of the envelope to define a compression region in the insulating portion. At step 1110, the compressed region is covered with a flexible bellows to define a passage for vapor, the end of the flexible bellows being sealed to the wall of the envelope outside the perforation. At step 1112, the envelope is filled with a working fluid. At step 1114, the condenser and evaporator ends of the envelope are sealed.

Fig. 12A to 12B are flowcharts of a third method of manufacturing a heat pipe according to an embodiment of the present application. At step 1202, an envelope is provided having a condenser end, an evaporator end, and an insulating portion therebetween. At step 1204, the walls of the envelope in the insulating portion are perforated to form a channel for the vapor. At step 1206, the wall of the envelope is offset toward the central axis of the envelope to define a compression region in the insulating portion. At step 1208, a core layer is disposed on an inner surface of the envelope for transporting the condensed working fluid from the condenser end to the evaporator end. At step 1210, the compressed region is covered with a flexible bellows to define a passage for vapor, the end of the flexible bellows being sealed to the wall of the envelope outside the perforation. At step 1212, the envelope is filled with a working fluid. At step 1214, the condenser and evaporator ends of the envelope are sealed.

The heat pipe of the present application provides a simple design suitable for mass production. At the same time, the thermal performance of the heat pipe is comparable to the inflexible heat pipes traditionally used in mass production, which suggests that a simple design has no drawbacks in thermal performance.

Although the present application and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (18)

1. A heat pipe (100, 200, 300, 400, 500, 600, 700), characterized by comprising:

an envelope (102, 202, 302) having a working fluid, the envelope (102, 202, 302) having a condenser end, an evaporator end, and an insulating portion between the condenser end and the evaporator end,

an inner core (108, 206, 504) layer disposed on an inner surface of the envelope (102, 202, 302) for conveying condensed working fluid from the condenser end to the evaporator end,

wherein the insulating portion comprises a perforated and compressed area (106, 204, 502) of the wall of the envelope (102, 202, 302) forming a passage for steam, in which compressed area the wall of the envelope (102, 202, 302) is offset towards the central axis of the envelope (102, 202, 302),

-a flexible bellows (104) covering the compression zone (106, 204, 502) and defining a channel (112) for the steam, the ends of the flexible bellows (104) being sealed to the walls of the envelope (102, 202, 302) outside the perforation.

2. The heat pipe (100, 200, 300, 400, 500, 600, 700) of claim 1, wherein the perforations of the wall of the envelope (102, 202, 302) comprise longitudinal through holes (110) made from two opposite sides of the envelope (102, 202, 302).

3. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to claim 1 or 2, wherein the compression zone (106, 204, 502) comprises planar channels for transporting the condensed working fluid, the planar channels (112) having one conical portion at each end.

4. A heat pipe (100, 200, 300, 400, 500, 600, 700) according to claim 3, wherein the planar channel is arranged substantially in the plane of the central axis of the envelope (102, 202, 302).

5. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any of claims 1 to 4, wherein the flexible bellows (104) has an elliptical cross-section.

6. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any one of claims 1 to 5, wherein the compression region (106, 204, 502) is provided with a securing means arranged on the wall of the envelope (102, 202, 302), which is offset towards the central axis of the envelope (102, 202, 302).

7. The heat pipe (100, 200, 300, 400, 500, 600, 700) of claim 6, wherein the securing means is one of a wire wrap, a foil wrap, and a contact resistance weld.

8. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any of claims 1-7, wherein the perforations of the wall of the envelope (102, 202, 302) comprise one or more additional through holes (304A-304N, 402) forming the passage of the steam.

9. The heat pipe according to any one of claims 1 to 8, wherein the perforations of the wall of the envelope (102, 202, 302) extend to a major portion of the circumference of the envelope (102, 202, 302).

10. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any of claims 1 to 9, wherein the wall and/or core (108, 206, 504) layer of the envelope (102, 202, 302) in the compression region (106, 204, 502) is provided with one or more transverse grooves and/or through holes (602).

11. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any one of claims 1 to 10, wherein a wick (108, 206, 504) outer layer is arranged on an inner surface of the flexible bellows (104), the wick outer layer being in communication with the wick (108, 206, 504) inner layer.

12. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any one of claims 1 to 11, wherein a second core (108, 206, 504) outer layer is arranged on an outer surface of the envelope (102, 202, 302) in the compression region (106, 204, 502), the second core outer layer being in communication with the core (108, 206, 504) inner layer.

13. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any one of claims 1 to 12, wherein the condenser end to the evaporator end is flat.

14. The heat pipe (100, 200, 300, 400, 500, 600, 700) according to any of claims 1 to 13, wherein an outer surface of the flexible bellows (104) is provided with a layer of a low heat conducting material.

15. The heat pipe (100, 200, 300, 400, 500, 600, 700) of any of claims 1-14, wherein the wick (108, 206, 504) comprises one or more of sintered particles, mesh, fibers, and grooves.

16. A method of manufacturing a heat pipe (100, 200, 300, 400, 500, 600, 700), comprising:

providing an envelope (102, 202, 302) having a condenser end, an evaporator end and an insulating portion therebetween,

a core (108, 206, 504) layer is disposed on an inner surface of the envelope (102, 202, 302) for transporting condensed working fluid from the condenser end to the evaporator end,

perforating a wall of the envelope (102, 202, 302) in the insulating portion to form a passage for steam,

offsetting the wall of the envelope (102, 202, 302) toward a central axis of the envelope (102, 202, 302) to define a compression region (106, 204, 502) in the insulating portion,

covering the compression zone (106, 204, 502) with a flexible bellows (104) to define a passage (112) for the steam, the ends of the flexible bellows (104) being sealed to the walls of the envelope (102, 202, 302) outside the perforation,

filling the envelope (102, 202, 302) with the working fluid,

-sealing the condenser end and the evaporator end of the envelope (102, 202, 302).

17. A method of manufacturing a heat pipe (100, 200, 300, 400, 500, 600, 700), comprising:

providing an envelope (102, 202, 302) having a condenser end, an evaporator end and an insulating portion therebetween,

perforating a wall of the envelope (102, 202, 302) in the insulating portion to form a passage for steam,

a core (108, 206, 504) layer is disposed on an inner surface of the envelope (102, 202, 302) for transporting condensed working fluid from the condenser end to the evaporator end,

offsetting the wall of the envelope (102, 202, 302) toward a central axis of the envelope (102, 202, 302) to define a compression region (106, 204, 502) in the insulating portion,

covering the compression zone (106, 204, 502) with a flexible bellows (104) to define a passage (112) for the steam, the ends of the flexible bellows (104) being sealed to the walls of the envelope (102, 202, 302) outside the perforation,

filling the envelope (102, 202, 302) with the working fluid,

-sealing the condenser end and the evaporator end of the envelope (102, 202, 302).

18. A method of manufacturing a heat pipe (100, 200, 300, 400, 500, 600, 700), comprising:

providing an envelope (102, 202, 302) having a condenser end, an evaporator end and an insulating portion therebetween,

perforating a wall of the envelope (102, 202, 302) in the insulating portion to form a passage for steam,

offsetting the wall of the envelope (102, 202, 302) toward a central axis of the envelope (102, 202, 302) to define a compression region (106, 204, 502) in the insulating portion,

a core (108, 206, 504) layer is disposed on an inner surface of the envelope (102, 202, 302) for transporting condensed working fluid from the condenser end to the evaporator end,

covering the compression zone (106, 204, 502) with a flexible bellows (104) to define a passage (112) for the steam, the ends of the flexible bellows (104) being sealed to the walls of the envelope (102, 202, 302) outside the perforation,

filling the envelope (102, 202, 302) with the working fluid,

-sealing the condenser end and the evaporator end of the envelope (102, 202, 302).