Heat pipe with sintered powder wick

Abstract

A heat pipe ( 10 ) includes a casing ( 12 ) and a sintered powder wick ( 14 ) arranged at an inner surface of the casing. The sintered powder wick is in the form of a multi-layer structure in a radial direction of the casing and at least one layer is divided into multiple sections in a longitudinal direction of the casing, and the multiple sections have powder sizes different from each other. The sections with large-sized powders are capable of reducing the flow resistance to the condensed liquid to flow back while the sections with small-sized powders are capable of providing a satisfactory capillary force for moving the condensed liquid.

1 . A heat pipe comprising: 
 a casing; and    a sintered powder wick arranged at an inner surface of the casing; wherein    the sintered powder wick is in the form of a multi-layer structure in a radial direction of the casing and at least one layer is divided into multiple sections in a longitudinal direction of the casing, and the multiple sections have powder sizes different from each other.    
   
   
       2 . The heat pipe of  claim 1 , wherein at least two layers of the sintered powder wick are divided into multiple sections and the sections of the two layers are constructed to have identical lengths.  
   
   
       3 . The heat pipe of  claim 1 , wherein at least two adjacent layers of the sintered powder wick are divided into multiple sections and at least two adjacent sections of the two layers in said radial direction have powder sizes different from each other.  
   
   
       4 . The heat pipe of  claim 1 , wherein at least two layers of the sintered powder wick are divided into multiple sections and the sections of the two layers are constructed to have different lengths.  
   
   
       5 . The heat pipe of  claim 1 , wherein the multiple layers of the sintered powder wick have different thicknesses.  
   
   
       6 . The heat pipe of  claim 1 , wherein each layer of the sintered powder wick is divided into multiple sections.  
   
   
       7 . The heat pipe of  claim 6 , wherein the sintered powder wick has a three-layer structure and each layer is divided into three sections.  
   
   
       8 . The heat pipe of  claim 1 , wherein the sintered powder wick is one of a sintered metal powder wick and a sintered ceramic powder wick.  
   
   
       9 . A method for manufacturing a heat pipe comprising steps of: 
 (1) providing a hollow casing;    (2) inserting a mandrel into the casing, and filling powders into said casing to form a layer of powder under the control of the mandrel;    (3) pre-sintering the layer of powder at a first temperature and drawing out the mandrel; (4) repeating the steps of (2) and (3) until at least two layers of powder are formed inside the casing, wherein in forming one of the at least two layers of powder, at least two groups of powder with different powder sizes are used; and    (5) sintering said at least two layers of powder at a second temperature higher than the first temperature, whereby a sintered powder wick with a multi-layer structure is formed inside the heat pipe.    
   
   
       10 . The method of  claim 9 , wherein the powders are one of metal powders and ceramic powders.  
   
   
       11 . The method of  claim 9 , wherein the powders are copper powders and the first temperature is about 630 degrees Celsius.  
   
   
       12 . The method of  claim 9 , wherein the powders are copper powders and the second temperature is about 950 degrees Celsius.  
   
   
       13 . The method of  claim 9 , wherein when forming each of the at least two layers of powder, said at least two groups of powder with different powder sizes are used.  
   
   
       14 . A heat pipe for transmitting heat from one section of the heat pipe to another section of the heat pipe comprising: 
 a metal hollow casing having an inner surface; and    a sintered powder wick in the casing and adjacent to the inner surface, the wick comprising a plurality of layers along a radial direction of the casing and a plurality of sections along a longitudinal direction of the casing, wherein two neighboring sections of one of the layers have different pore sizes.    
   
   
       15 . The heat pipe of  claim 14 , wherein two neighboring sections of two neighboring layers have different pore sizes.  
   
   
       16 . The heat pipe of  claim 14 , wherein the heat pipe has an evaporating section and a condensing section, and one of the sections of the sintered powder wick is located and has a length corresponding to the evaporating section and another of the sections of the sintered powder wick is located and has a length corresponding to the condensing section.  
   
   
       17 . The heat pipe of  claim 14 , wherein the layers have different thickness.  
   
   
       18 . The heat pipe of  claim 14 , wherein the sections have different lengths.  
   
   
       19 . The heat pipe of  claim 17 , wherein the sections have different lengths.