Flat heat pipe and method for manufacturing flat heat pipe

Abstract

An exemplary flat heat pipe includes a hollow, flattened casing and a first wick structure and a second wick structure received in the casing. The casing includes a top plate and a bottom plate opposite to the top plate. The first wick structure is folded by a steel sheet with a plurality of pores, and the second wick structure is made of sintered metal powder. The first and second wick structures are disposed at inner sides of the bottom and top plates of the casing, respectively. The first and second wick structures contact each other. The casing defines two vapor channels at opposite lateral sides of the combined first and second wick structures, respectively.

1 . A flat heat pipe comprising:
 a hollow, flattened casing, comprising a top plate and a bottom plate opposite to the top plate; and   a first wick structure and a second wick structure received in the casing, the first wick structure being made of a folded steel sheet with a plurality of pores, the second wick structure being made of sintered metal powder, the first and second wick structures disposed at inner surfaces of the bottom and top plates of the casing, respectively, the first and second wick structures contacting each other, the casing defining two vapor channels at opposite lateral sides of the combined first and second wick structures, respectively.   
     
     
         2 . The flat heat pipe of  claim 1 , wherein a bottom of the first wick structure is attached to the bottom plate, a top of the second wick structure is attached to the top plate, and a top of the first wick structure not in contact with the bottom plate is attached to a bottom of the second wick structure not in contact with the top plate. 
     
     
         3 . The flat heat pipe of  claim 1 , wherein the first wick structure is aligned with the second wick structure, and the second wick structure is attached to a middle of the first wick structure. 
     
     
         4 . The flat heat pipe of  claim 3 , wherein the second wick structure tapers from the top thereof farthest away from the first wick structure toward the bottom thereof in contact with the first wick structure, and the bottom of the second wick structure in contact with the first wick structure forms a rounded ridge attached to the middle of the first wick structure. 
     
     
         5 . The flat heat pipe of  claim 3 , wherein the bottom of the second wick structure is attached to the top of the first wick structure, and the second wick structure is generally cuboid. 
     
     
         6 . The flat heat pipe of  claim 1 , wherein a center of the first wick structure and a center of the second wick structure are offset from each other as would be viewed in transverse cross section of the casing. 
     
     
         7 . The flat heat pipe of  claim 6 , wherein the second wick structure tapers from a top thereof farthest away from the first wick structure toward a bottom thereof attached to the first wick structure. 
     
     
         8 . The flat heat pipe of  claim 6 , wherein one side of the second wick structure is attached to the first wick structure, and the second wick structure is generally cuboid. 
     
     
         9 . The flat heat pipe of  claim 1 , wherein the second wick structure is substantially triangular prism-shaped or cuboid, and a bottom of the second wick structure not in contact with the casing is attached to the first wick structure. 
     
     
         10 . The flat heat pipe of  claim 1 , wherein the first wick structure is a flattened structure. 
     
     
         11 . A method for manufacturing a flat heat pipe, the method comprising:
 providing a cylindrical mandrel, a hollow cylindrical tube and a steel sheet with a plurality of pores, the mandrel defining an elongated notch and an elongated cutout in a circumferential surface thereof, the notch and the cutout located opposite each other across a center axis of the mandrel, and an inner diameter of the tube being substantially equal to an outer diameter of the mandrel;   folding the steel sheet to form a first wick structure;   inserting the mandrel and the first wick structure into the tube, wherein the first wick structure is received in the notch of the mandrel;   filling an amount of metal powder into the cutout of the mandrel in the tube, and sintering the metal powder to form a second wick structure;   drawing the mandrel out of the tube, wherein the first and second wick structures remain attached to portions of an inner surface of the tube, and face each other;   injecting a working medium into the tube, and evacuating and sealing the tube; and   flattening the tube until the first wick structure becomes flattened and the second wick structure contacts the first wick structure, thus forming a flat heat pipe, wherein the flat heat pipe defines two vapor channels at opposite lateral sides of the combined first and second wick structures, respectively.   
     
     
         12 . The method for manufacturing a flat heat pipe of  claim 11 , wherein the cutout defines a generally arcuate cross section, and after the mandrel is drawn out of the tube, the second wick structure has a generally arcuate cross section. 
     
     
         13 . The method for manufacturing a flat heat pipe of  claim 12 , wherein after the tube is flattened, the second wick structure is generally cuboid. 
     
     
         14 . The method for manufacturing a flat heat pipe of  claim 11 , wherein an inmost extremity of the cutout is planar, and after the mandrel is drawn out of the tube, a transverse cross section of the second wick structure comprises a straight line and an arcuate line connecting the straight line, with the arcuate line corresponding to a portion of the second wick structure attached to the inner surface of the tube. 
     
     
         15 . The method for manufacturing a flat heat pipe of  claim 14 , wherein after the tube is flattened, the second wick structure generally tapers from one side thereof farthest away from the first wick structure toward another side thereof in contact with the first wick structure. 
     
     
         16 . The method for manufacturing a flat heat pipe of  claim 11 , wherein the notch defines an arcuate cross section, and the first wick structure defines an arcuate cross section before the tube is flattened. 
     
     
         17 . The method for manufacturing a flat heat pipe of  claim 11 , wherein the first wick structure is pulled by the tube into a flattened shape during the flattening of the tube. 
     
     
         18 . The method for manufacturing a flat heat pipe of  claim 11 , wherein the first wick structure directly faces or obliquely faces the second wick structure before the tube is flattened. 
     
     
         19 . A flat heat pipe comprising:
 a hollow, flattened casing, comprising a top plate and a bottom plate opposite to the top plate; and   a first wick structure and a second wick structure attached to inner sides of the bottom and top plates of the casing, respectively, the first wick structure comprising a folded steel sheet with a plurality of pores, the second wick structure comprising sintered metal powder, the first and second wick structures snugly contacting each other, the casing defining two separate vapor channels at opposite lateral sides of the combined first and second wick structures, respectively;   wherein the flat heat pipe has an evaporator section and a condenser section respectively located at opposite ends thereof along a longitudinal direction thereof, and the first wick structure extends longitudinally through the evaporator section and the condenser section.   
     
     
         20 . The flat heat pipe of  claim 19 , wherein the first wick structure obliquely faces or is aligned with the second wick structure.