Flat heat pipe

Abstract

A heat pipe a flat heat pipe having enhanced heat transport capacity is provided. The flat heat pipe 1 comprises a working fluid encapsulated in a container 2, a first wick 11 that returns the working fluid from a condensing portion 4 to an evaporating portion 3 by a capillary pumping, and a second wick 12 that spreads the working fluid returned thereto over an inner face of the container by a capillary pumping. The second wick is formed only in the evaporating portion 3 to extend in a circumferential direction on the inner face of the container 2.

What is claimed is: 
     
         1 . A flat heat pipe, comprising:
 a sealed container having a pair of upper and lower flat walls extending in a length direction;   a working fluid encapsulated in the container;   an evaporating portion that is situated on one of the longitudinal ends of the container at which evaporation of the working fluid takes place;   a condensing portion that is situated on the other longitudinal end of the container at which condensation of the working fluid takes place;   a first wick formed of a bundled fibers or a porous structure that extends in the length direction of the container to return the working fluid condensed at the condensing portion to the evaporating portion by a capillary pumping; and   a second wick that is formed by forming a groove on an inner face of the container only in the evaporating portion to spread the working fluid returned thereto over the inner face within the evaporating portion by a capillary pumping;   wherein the first wick is formed on at least one of the upper flat wall or the lower flat wall; and   wherein the second wick transversely extends underneath the first wick to be closed partially by the first wick.   
     
     
         2 . The flat heat pipe as claimed in  claim 1 , wherein the second wick is formed on the inner face of the container in the evaporating portion in a spiral manner. 
     
     
         3 . The flat heat pipe as claimed in  claim 1 , wherein the second wick is formed on the inner face of the container in the evaporating portion in a circular manner. 
     
     
         4 . The flat heat pipe as claimed in  claim 1 , wherein the second wick is formed only on the inner face of one of the upper flat face and the lower flat face on which the first wick is formed. 
     
     
         5 . The flat heat pipe as claimed in  claim 1 , wherein the second wick includes an opening portions extending from both sides of the first wick in the circumferential direction. 
     
     
         6 . The flat heat pipe as claimed in  claim 1 , wherein the porous structure is formed by sintering metal powders. 
     
     
         7 . The flat heat pipe as claimed in  claim 1 , wherein the first wick is formed of copper fibers. 
     
     
         8 . The flat heat pipe as claimed in  claim 1 , wherein the first wick is formed of carbon fibers. 
     
     
         9 . The flat heat pipe as claimed in  claim 1 , wherein the first wick is formed of a mixture of carbon fibers and copper fibers.