HEAT PIPE

Abstract

A heat pipe (10) includes a metal casing (12) having a closed end (14) and a sealed end (16) located opposite to the closed end. The sealed end of the heat pipe includes a cramped section (16a) having a wave-shaped cross-section. A device for sealing an open end (16a) of the heat pipe includes a pair of clamping blocks (26) for clamping the open end of the heat pipe in a first direction and a pair of pressing blocks (22, 24) located at opposite sides of the open end of the heat pipe and being capable of moving towards each other, thereby approaching the open end of the heat pipe in a second direction perpendicular to the first direction. The pressing blocks have a pair of complementary wave-shaped forming faces (22a, 24a) formed thereon.

Description

FIELD OF THE INVENTION

The present invention relates generally to an apparatus for transfer or dissipation of heat from heat-generating components, and more particularly to a heat pipe.

DESCRIPTION OF RELATED ART

It is well known that heat is generated by a variety of electronic components such as central processing units (CPUs) of computers during their normal operations. Since the workability and stability of these electronic components depend, to a large extent, on timely removal of the heat generated by them, cooling devices such as heat sinks plus cooling fans are commonly used in order to remove the generated heat away. Currently, heat pipes are widely used in combination with the cooling devices so as to timely and effectively remove the heat from these electronic components.

Heat pipes are an effective heat transfer means due to the application of the phase-change mechanism. A heat pipe is usually a vacuum casing containing therein a working fluid. In most cases, a wick structure is provided inside the heat pipe, lining an inner wall of the casing. In operation, a cooling device such as a plurality of metal fins is attached to a condensing section of the heat pipe and an evaporating section of the heat pipe is maintained in thermal contact with a heat-generating component. The working fluid contained in the evaporating section of the heat pipe absorbs heat generated by the heat-generating component and evaporates into vapor which thereafter moves towards the condensing section of the heat pipe where the heat carried by the vapor is released to ambient environment via the metal fins thermally contacting the condensing section. As a result, the vapor is condensed into condensate in the condensing section and then the condensate is drawn, via the wick structure arranged in the heat pipe, back to the evaporating section for being available again for evaporation.

Generally, a heat pipe is made by filling a working fluid into a tube with an open end and a closed end. In the tube, a wick structure is disposed. Then, the tube is vacuumed via the open end and the open end of the tube is sealed. Among these steps, the sealing step is extremely important because a defective sealing will directly affect the performance and life span of the heat pipe.

Currently, a technique of sealing the heat pipe involves filling a tin block or epoxy material into the open end of the heat pipe. However, by using this technique, a complicated process is generally required, which adds manufacturing cost to the heat pipe. Also, if the heat pipe made by this technique is thereafter bent or flattened in order to be applicable in some specific situations where the heat pipe is desired to be in a curved or flattened configuration, the sealed open end of the heat pipe will deform and a small gap will accordingly occur at the sealing interface between the sealed open end of the heat pipe and the filling material. Due to the gap, the heat pipe will gradually lose its vacuum condition and a reliability issue will be raised. As a result, the application of the heat pipe made by this technique is somewhat limited.

Mechanical pressing is another technique applicable for sealing the heat pipe. In this technique, a device is used to flatten a section of the open end of the heat pipe into a flattened sealing section and then, a distal end portion of the open end is soldered so as to hermetically seal the heat pipe. In this case, the distal end portion is formed as a ball. Since the flattened sealing section is thin and flat, it generally has a low mechanical strength and is therefore easily deformed when subject to external forces or high temperatures. For example, if the heat pipe made by this technique is vertically soldered to a heat sink under a high temperature, the flattened sealing section of the heat pipe will soften and deform due to a weight of the ball-like distal end portion, as shown in FIG. 6.

Therefore, it is desirable to provide a heat pipe which overcomes the foregoing disadvantages.

SUMMARY OF INVENTION

The present invention relates, in one aspect, to a heat pipe. The heat pipe includes a metal casing having a closed end and a sealed end located opposite to the closed end. The sealed end of the heat pipe includes a cramped section having a wave-shaped cross-section.

The present invention relates, in another aspect, to a device for sealing an open end of a heat pipe. The device includes a pair of clamping blocks for clamping the open end of the heat pipe in a first direction and a pair of pressing blocks located at opposite sides of the open end of the heat pipe and being capable of moving towards each other, thereby approaching the open end of the heat pipe in a second direction perpendicular to the first direction. The pressing blocks have a pair of complementary wave-shaped forming faces formed thereon. The pressing blocks presses the open end of the heat pipe into the cramped section of the sealed end of the heat pipe.

Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an isometric view of a heat pipe in accordance with one embodiment of the present invention;

FIGS. 2-5 are cross-sectional views of a device used in manufacturing the heat pipe of FIG. 1 at different steps; and

FIG. 6 is a side elevation view of a heat pipe in accordance with the conventional art.

DETAILED DESCRIPTION

FIG. 1 illustrates a heat pipe 10 in accordance with one embodiment of the present invention. The heat pipe 10 includes a metal casing 12 having an integrally closed end 14 and a sealed end 16 located opposite to the closed end 14. The sealed end 16 includes a distal cramped section 16a and a transitional tapered section 16b located between the metal casing 12 and the cramped section 16a. The cramped section 16a is centrally aligned with a longitudinal axis of the metal casing 12. The cramped section 16a has a wave-shaped cross-section, which is symmetric with respect to the longitudinal axis of the metal casing 12. In this figure, the cramped section 16a has an S-shaped cross-section.

Generally, the cramped section 16a is formed by mechanically pressing an original open end 16a′ of the metal casing 12 through a device, whereby the heat pipe 10 is sealed. With reference also to FIGS. 2-5, such a device is shown for forming the cramped section 16a and accordingly sealing the heat pipe 10. The device includes a pair of clamping blocks 26 and a pair of pressing blocks 22, 24. The clamping blocks 26 are used to clamp the open end 16a′ of the metal casing 12 in a first, horizontal direction, as viewed from FIG. 2. The pressing blocks 22, 24 are located at opposite sides of the open end 16a′ and are capable of moving towards each other in a second, vertical direction perpendicular to the first, horizontal direction, as viewed from FIG. 2. The pressing blocks 22, 24 have a pair of complementary S-shaped forming faces 22a, 24a formed thereon, respectively, which are used to form the S-shaped cramped section 16a of the heat pipe 10.

In operation, the open end 16a′ of the metal casing 12 is sandwiched between the two clamping blocks 26, as shown in FIG. 2. Then, the pressing blocks 22, 24 are brought to move towards each other, thereby approaching the open end 16a′ in a high speed. As a result, the open end 16a′ is pressed by the pressing blocks 22, 24 into the S-shaped cramped section 16a′, as shown in FIG. 3. During the movement toward the open end 16a′, the pressing blocks 22, 24 are guided between the clamping blocks 26, which are spaced from each other by a distance substantially the same as a diameter of the open end 16a′ of the casing 12. Thereafter, a cutter 32 is used to cut away a distal end portion of the cramped section 16a formed by the above-mentioned mechanical pressing step in order to obtain the cramped section 16a with a desirable length and a straight edge, as shown in FIG. 4. Finally, the pressing blocks 22, 24 are removed away from the formed cramped section 16a, as shown in FIG. 5. In order to ensure that the heat pipe 10 sealed by this device is hermetically sealed, a subsequent soldering process may be applied to the formed cramped section 16a. By using the present device, the sealing process to the heat pipe 10 can be performed in a very short time period, typically with a cycle time of about 5 seconds.

In the present heat pipe 10, the wave-shaped cramped section 16a of the sealed end 16 has a relatively high mechanical strength. Thus, the heat pipe 10 is hermetically sealed and has a good mechanical performance. When the heat pipe 10 is soldered to a heat sink under a high temperature, the sealed end 16 thereof will not deform. In use, a portion of the heat pipe 10 neighboring the closed end 14 is used as an evaporating portion for receiving heat from a heat generating electronic device, such as a CPU, and a portion neighboring the sealed end 16 is used as a condensing portion for dissipating the heat.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A heat pipe comprising a metal casing having an integrally closed end and a sealed end located opposite to the closed end, the sealed end including a cramped section having a wave-shaped cross-section.

2. The heat pipe of claim 1, wherein the cramped section has an S-shaped cross-section.

3. The heat pipe of claim 1, wherein the cramped section is symmetric with respect to a longitudinal axis of the metal casing.

4. The heat pipe of claim 1, wherein the cramped section is centrally aligned with a longitudinal axis of the metal casing.

5. The heat pipe of claim 1, wherein the sealed end further includes a tapered section, the tapered section being located between the metal casing and the cramped section.

6. A device for sealing an open end of a heat pipe comprising:

a pair of clamping blocks for clamping the open end of the heat pipe in a first direction; and

a pair of pressing blocks located at opposite sides of the open end of the heat pipe and being capable of moving towards each other, thereby approaching the open end of the heat pipe in a second direction perpendicular to the first direction, the pressing blocks having a pair of complementary wave-shaped forming faces formed thereon.

7. The device of claim 6, wherein each of the complementary wave-shaped forming faces has an S-shaped configuration.

8. A heat pipe comprising:

a casing having an integrally closed end near an evaporating portion of the heat pipe and a cramped sealed end near a condensing portion of the heat pipe, wherein the cramped sealed end has a wave-like cross section.

9. The heat pipe of claim 8, wherein the wave-like cross section has an S-shaped configuration.

10. The heat pipe of claim 9, wherein the S-shaped sealed end is centrally aligned with a longitudinal axis of the casing.

11. The heat pipe of claim 10 further comprising a tapered section adjacent to the cramped sealed end.