Patent Application
20060260786
The present invention relates in general to a composite wick structure of a heat pipe, and more particularly, to a composite wick structure fabricated from a multi-layer woven mesh and a sintered powder layer.
Having the features of high heat transmission capability, high-speed heat conductance, high thermal conductivity, light weight, mobile-elements free, simple structure, the versatile application, and low power for heat transmission, heat pipes have been popularly applied in heat dissipation devices in the industry. The conventional heat pipe includes a wick structure on an internal sidewall of a tubular member. The wick structure typically includes a woven mesh or sintered powder to aid in transmission of working fluid.
However, the woven mesh or the sintered powder each has advantages and drawbacks.
For example, the fine and dense structure of the sintered-powder wick structure provides better capillary force for reflow of the liquid-state working fluid. However, during fabrication, an axial rod has to be inserted into the tubular member to serve as a support member of the wick structure during the sintering process, so as to avoid collapse of the powdered which has not been sintered yet. Therefore, the thickness of the sintered powder wick structure is thicker. Consequently, the capillary thermal resistance is increased to be disadvantageous to the heat transmission. Further, requirement of the axial rod hinders the mass production of the heat pipe and causes fabrication and quality issues of the heat pipe.
The woven mesh wick structure does not require the axial rod, such that the problems of the sintered powder wick structure do not encounter. Further, the woven mesh wick structure is more easily to fabricate compared to the sintered-powder wick structure. However, as the woven mesh is made by weaving metal wires, the porosities are larger to provide a poor capillary effect. The working fluid is less easily to reflow, and the thermal conduction efficiency is affected.
Thus, there still is a need in the art to address the aforementioned deficiencies and inadequacies.
The present invention provides a composite wick structure of a heat pipe. The composite structure adapts the advantages of both the multi-layer woven-mesh and the sintered-powder wick structure, such that the transmission capability of the wick structure is maintained, and the heat conduction performance of the heat pipe is improved, while the problems caused by the axial rod are resolved.
A heat pipe provided by the present invention includes a tubular member with an internal sidewall, and a composite wick structure including a multi-layer woven mesh and a sintered-powder layer. The multi-layer woven mesh is curled to cover on and extend over the internal sidewall. The sintered-powder layer is coated on a portion of the multi-layer woven mesh and the internal sidewall to extend along a longitudinal direction of the tubular member. By the strong capillary force provided by the sintered-powder layer, the working fluid at the liquid phase easily reflows back to the bottom of the heat pipe, such that the heat transmission efficiency is greatly enhanced.
These and other objectives of the present invention will become obvious to those of ordinary skill in the art after reading the following detailed description of preferred embodiments.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
These as well as other features of the present invention will become more apparent upon reference to the drawings therein:
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The tubular member 10 is preferably in the form of a cylindrical hollow tube having an internal sidewall 102 and two open ends 100, 101. After filling a working fluid, a vacuum process is performed so that the tubular member 10 can be closed and sealed at both ends 100, 101 by a shrinking and sealing process.
Referring further to
By the above processes, a composite wick structure is obtained.
Together referring to
Therefore, the composite wick 11 of the heat pipe 1 includes both the advantages of the multi-layer woven mesh 110 and the sintered-powder layer 111. The sintered-powder layer 111 provides better capillary force for reflow of the liquid-state working fluids without need of the axial rod anymore. Meanwhile, the multi-layer woven mesh 110 is convenient for installation with secure attachment to the sidewall 102 of the tubular member 10. The multi-layer woven mesh 110 is not easy to collapse when a high-temperature annealing process is performed so that the wick structure 11 will have a reliable support.
This disclosure provides exemplary embodiments of wick structure of a heat pipe. The scope of this disclosure is not limited by these exemplary embodiments. Numerous variations, whether explicitly provided for by the specification or implied by the specification, such as variations in shape, structure, dimension, type of material or manufacturing process may be implemented by one of skill in the art in view of this disclosure.
