1. Technical Field
The present disclosure relates to heat pipes and, more particularly, to a plate-type heat pipe having good heat dissipation efficiency and stable and reliable performance.
2. Description of Related Art
Generally, plate-type heat pipes efficiently dissipate heat from heat-generating components such as a central processing unit (CPU) of a computer. A conventional plate-type heat pipe comprises a top plate and a bottom cover hermetically contacting the top plate to form a container. A wick structure is adhered to an inner surface of the bottom cover. Working fluid is contained in the container. All parts of the wick structure have the same thickness. When the bottom cover of the plate-type heat pipe absorbs heat of the heat-generating component, the working fluid is vaporized to absorb the heat of the bottom cover.
If the wick structure is too thick, a part of the vaporized working fluid is retarded by the wick structure when the vaporized working fluid is escaping from the wick structure toward the top plate. Therefore, a plurality of bubbles is formed in and on the wick structure. The bubbles tend to block pores of the wick structure, and retard the flow of condensed working fluid into the wick structure. When this happens, the amount of condensed working fluid contained in the wick structure decreases. What working fluid there is in the wick structure may absorb the heat of the bottom cover too slowly, whereby heat is accumulated on the bottom cover, and the plate-type heat pipe overheats. Conversely, if the wick structure is too thin, the working fluid contained in the wick structure is liable to be dried off altogether. When this happens, the plate-type heat pipe will be destroyed.
What is needed, therefore, is a plate-type heat pipe having good heat dissipation efficiency and stable, reliable performance.
In the drawings, all the views are schematic.
Referring to
The container 10 is made of copper, aluminum, or an alloy thereof. The container 10 includes an elongated condensing plate 11 and a bowl-shaped evaporating plate 13 integrally formed as a single, one-piece, monolithic body without any seams. The evaporating plate 13 absorbs heat of heat-generating components (not shown) such as electronic devices. Then the condensing plate 11 dissipates the heat, transferred from the evaporating plate 13, to the ambient environment. In alternative embodiments, the elongated condensing plate 11 and the bowl-shaped evaporating plate 13 can be distinct pieces, with the bowl-shaped evaporating plate 13 hermetically contacting the condensing plate 11.
The evaporating plate 13 includes an elongated heat absorbing portion 131, two transition portions 133, two extending portions 134, and two sidewalls 135. The two transition portions 133 extend upwardly and outwardly from opposite lateral edges of the heat absorbing portion 131, respectively, and are symmetrically opposite each other. The two extending portions 134 extend outwardly along opposite horizontal directions from outer edges of the transition portions 133, respectively. The sidewalls 135 extend upwardly from outer edges of the extending portions 134, respectively. The sidewalls 135 are perpendicular to the extending portions 134. The extending portions 134 are parallel to the heat absorbing portion 131, and are closer to the condensing plate 11 than the heat absorbing portion 131. In the illustrated embodiment, top ends of the sidewalls 135 are integrally formed with two ends of the condensing plate 11. That is, the evaporating plate 13 and the condensing plate 11 are a single body of the same material without any seams. In other embodiments, the evaporating plate 13 and the condensing plate 11 can be separate bodies hermetically connected together.
The wick structure 30 is made of sintered metallic powder, and includes an elongated first wick member 31 and a second wick member 33. The first wick member 31 is adhered to an inner surface of the condensing plate 11. The second wick member 33 is adhered to an inner surface of the evaporating plate 13. The second wick member 33 is adapted for providing a capillary force to draw condensed working fluid from the first wick member 31 back toward a middle portion of the second wick member 33. Opposite ends of the second wick structure 33 interconnect opposite ends of the first wick member 31, respectively, thereby forming the continuous wick structure 30.
Referring also to
The first wick portion 331 is adhered to an inner surface of the heat absorbing portion 131 of the evaporating plate 13. The second wick portions 333 extend upwardly and outwardly from opposite ends of the first wick portion 331, respectively, and are symmetrically opposite each other. The second wick portions 333 are adhered to inner surfaces of the transition portions 133 of the evaporating plate 13. The first wick portion 331 is thinner than each of the second wick portions 333 and each of the third wick portions 335. Thus, in general, the working fluid contained in the first wick portion 331 is vaporized faster than working fluid at a comparable location in a conventional plate-type heat pipe. Accordingly, the heat of the heat absorbing portion 131 is transferred quickly. The third wick portions 335 are horizontal, and extend outwardly from the second wick portions 333, respectively. The third wick portions 335 are adhered to inner surfaces of the extending portions 134 of the evaporating plate 13. The fourth wick portions 337 are adhered to inner surfaces of the sidewalls 135 of the evaporating plate 13, and perpendicularly connect outer ends of the third wick portions 335, respectively.
Each of the third wick portions 335 defines a plurality of rectangular or square through holes 3353 therein. In the illustrated embodiment, the through holes 3313 are arranged in a regular m×n array. The working fluid contained in the first wick portion 331 absorbs the heat of the heat absorbing portion 131 quickly, and then is vaporized. The vaporized working fluid moves to the first wick member 31 to dissipate the heat, and condenses at the first wick member 31. The fourth wick portions 337, third wick portions 335, and second wick portions 333 cooperatively guide the condensing working fluid contained in or accumulated on the first wick member 31 back to the first wick portion 331. Because the through holes 3353 are defined in the third wick portions 335, a portion of the condensing working fluid is contained in the through holes 3353. Thus, the amount of working fluid contained in the second wick member 33 is increased relative to working fluid at a comparable location in a conventional plate-type heat pipe. The working fluid contained in the through holes 3353 can ensure that a quantity of the condensing working fluid in the first wick portion 331 is sufficient even though evaporation of the working fluid in the first wick portion 331 is faster. Therefore, the plate-type heat pipe avoids becoming dried off. Thus, the plate-type heat pipe has stable, reliable performance. In alternative embodiments, the through holes 3353 can be triangular, circular, oval-shaped, elliptical, etc.
Referring to
Because the auxiliary wick portions 332 are much thinner than the third wick portion 335, a majority of each of the through holes 3353 is available to accommodate working fluid. The condensing working fluid is contained in pores of the second wick member 33 and the upper portions of the through holes 3353 not occupied by the auxiliary wick portions 332. Therefore, a quantity of the condensing working fluid in the second wick member 33 is increased relative to working fluid at a comparable location in a conventional plate-type heat pipe. In addition, a capillary force of the second wick member 33 is improved because of the auxiliary wick portions 332 filling the bottoms of the through holes 3353 of the third wick portion 335. Therefore, the condensed working fluid flows back to the first wick portion 331 more quickly. Thus, stable and reliable performance of the plate-type heat pipe can be ensured.
Referring to
Referring to
Referring to
It is to be understood, however, that even though numerous characteristics and advantages of various embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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 disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Number | Date | Country | Kind |
---|---|---|---|
200910309578.4 | Nov 2009 | CN | national |