Heat pipe with variable grooved-wick structure and method for manufacturing the same

Abstract

A heat pipe ( 10 ) includes a casing ( 11 ), a plurality of grooves ( 12, 13 ) defined in the casing, and working fluid contained in the casing. The casing includes a first portion ( 14 ) and a second portion ( 15 ) having a smaller diameter than the first portion. The grooves ( 12 ) at the first portion of the casing have greater apex angles and smaller groove width than those of the grooves ( 13 ) at the second portion. A method for manufacturing the heat pipe includes the steps of: providing a casing with a plurality of grooves defined in an inner wall thereof; shrinking a diameter of one portion of the casing to enable the portion to function as an evaporator section of the heat pipe; vacuuming and placing a predetermined quantity of working fluid in the casing; sealing the casing to obtain the heat pipe.

1 . A heat pipe comprising:
 a casing comprising a first portion and a second portion having a smaller diameter than the first portion;   a plurality of grooves defined in an inner wall of the casing; and   a predetermined quantity of bi-phase working fluid contained in the casing;   wherein the grooves at the first portion of the casing have smaller groove width than that of the grooves at the second portion.   
   
   
       2 . The heat pipe of  claim 1 , wherein the grooves extends along a central axis of the casing. 
   
   
       3 . The heat pipe of  claim 1 , wherein the grooves at the first portion of the casing have greater apex angles than that of the grooves at the second portion. 
   
   
       4 . The heat pipe of  claim 1 , wherein the first portion is an evaporator section of the heat pipe, whilst the second section is a condenser section of the heat pipe. 
   
   
       5 . The heat pipe of  claim 4 , wherein the evaporator section is disposed at an end of the heat pipe. 
   
   
       6 . The heat pipe of  claim 4 , wherein the evaporator section is disposed at a middle portion of the heat pipe. 
   
   
       7 . The heat pipe of  claim 1  further comprising a transition section disposed between the first portion and the second portion, a diameter of the transition section being gradually decreased from the second portion towards the first portion. 
   
   
       8 . The heat pipe of  claim 1 , wherein the casing of the heat pipe is flat in profile. 
   
   
       9 . A method for manufacturing a heat pipe with variable grooved-wick structure comprising the steps of:
 providing a casing with a plurality of tiny grooves defined in an inner wall thereof;   shrinking a diameter of one portion of the casing via a shrinkage tool to enable it to function as an evaporator section of the heat pipe;   vacuuming and placing a predetermined quantity of working fluid in the casing; and   sealing the casing to obtain the heat pipe.   
   
   
       10 . The method as described in  claim 9 , wherein the grooves are axially carved in the inner wall of the casing. 
   
   
       11 . The method as described in  claim 9 , wherein the shrinkage tool is a high speed spinning tube shrinkage tool, the shrinkage process of the evaporator section comprises the step of controlling the high speed spinning tube shrinkage tool to move towards the evaporator section of the casing along a central longitudinal axis thereof so as to shrink the diameter thereof. 
   
   
       12 . The method as described in  claim 11 , wherein the high speed spinning tube shrinkage tool comprises a tapered portion which enables to compress an outer wall of the evaporator section so as to shrink the diameter thereof and a guiding portion which guides the movement of the high speed spinning tube shrinkage tool. 
   
   
       13 . The method as described in  claim 12 , wherein the high speed spinning tube shrinkage tool further comprises a diminished portion, the tapered portion being disposed between the guiding portion and the diminished portion. 
   
   
       14 . The method as described in  claim 9 , wherein the shrinkage tool is a spinning stamping tube shrinkage tool, the shrinkage process of the evaporator section comprises the step of controlling the spinning stamping tube shrinkage tool to move towards the evaporator section of the casing along a radial direction of the casing so as to shrink the diameter of the evaporator section. 
   
   
       15 . The method as described in  claim 14 , wherein the shrinkage process of the evaporator section further comprises the step of controlling the spinning stamping tube shrinkage tool to move towards the evaporator section of the casing along a central longitudinal axis of the heat pipe in order to obtain a predetermine length for the evaporator section. 
   
   
       16 . The method as described in  claim 14 , wherein the spinning stamping tube shrinkage tool includes more than two sub-tools with arc-shaped inner surfaces thereof distributed around an imaginary circle which is coaxial with and surrounds the casing. 
   
   
       17 . The method as described in  claim 16 , wherein each of the sub-tools comprises diminished portion and a tapered portion connecting with the diminished portion at an end thereof, a diameter of the tapered portion being gradually increased from the end towards an opposite end thereof. 
   
   
       18 . The method as described in  claim 17 , wherein each of the sub-tools further comprises an enlarged portion connecting with the tapered portion at the opposite end thereof.