Patent Application
20110094712
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 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. In addition, if the pores of the wick structure are too small, the vaporized working fluid also tends to be retarded by the wick structure. In these kinds of situations, a plurality of bubbles is formed in and on the wick structure. The bubbles tend to block the 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. In due course, the plate-type heat pipe may overheat, and the heat dissipation efficiency of the plate-type heat pipe is reduced.
What is needed, therefore, is a plate-type heat pipe having good heat dissipation efficiency and stable, reliable performance.
Referring to
The container 10 is made of copper, aluminum, or an alloy thereof, and includes an elongated condensing plate 11 and a bowl-shaped evaporating plate 13 hermetically contacting the condensing plate 11. The evaporating plate 13 absorbs heat generated by one or more components (not shown) such as electronic devices. The condensing plate 11 dissipates heat, transferred from the evaporating plate 13, to the ambient environment.
The evaporating plate 13 includes an elongated heat absorbing portion 131, two transition portions 133, two extending portions 134 and two sidewalls 135. The 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 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 133, respectively. The sidewalls 135 are perpendicular to the extending portions 133. 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 two separate bodies 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. A plurality of capillary pores (not labeled) are defined in the first wick member 31 and the second wick member 33 for providing a capillary force to draw condensed working fluid back toward a middle portion of the second wick member 33 (see also below). 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. 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 first wick portion 331 defines a plurality of rectangular or square through holes 3313 therein. In the illustrated embodiment, the through holes 3313 are arranged in a regular m x n array. Because the through holes 3313 are defined in the first wick portion 331, a portion of the working fluid is contained in the through holes 3313 and contacts the heat absorbing portion 131 of the evaporating plate 13 directly. The working fluid contained in the through holes 3313 and 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 in the through holes 3313 escapes the first wick portion 331 from the through holes 3313 directly. Therefore the working fluid in the first wick portion 331 escapes from the first wick portion 331 via the through holes 3313 quickly. Accordingly, unlike in other conventional plate-type heat pipes, few or even no bubbles accumulate in the first wick portion 331 when the plate-type heat pipe is in operation. Thus, the heat dissipation efficiency of the plate-type heat pipe is improved. In alternative embodiments, the through holes 3313 can be triangular, circular, oval-shaped, elliptical, etc, and can be larger than the pores of the first wick member 31 and the second wick member 33.
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 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. Each fourth wick portion 337 is adhered to an inner surface of the corresponding sidewall 135 of the evaporating plate 13, and fills a corner formed by the sidewall 135 and the corresponding extending portion 134. A cross-section of each fourth wick portion 337 is substantially triangular. That is, a transverse thickness (horizontal, from left to right, as viewed in
Referring to
Because the auxiliary wick portions 332 are thinner than the first wick portion 331, heat transfer paths of the working fluid in the heat absorbing portion 131 are generally shorter than those of conventional plate-type heat pipes. Accordingly, the working fluid is vaporized quickly. Thus, the heat dissipation efficiency of the plate-type heat pipe is improved. In addition, a capillary suction of the second wick member 33 is improved because of the auxiliary wick portions 332 filling bottoms of the through holes 3313 of the first wick portion 331. 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
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 |
|---|---|---|---|
| 200910308623.4 | Oct 2009 | CN | national |
