Heat pipe

Abstract

A heat pipe able to switch between operation and suspension of heat transport when used for a bottom heat type and able to prevent the condensed working medium from dropping to the evaporator side and a waste heat recovery system using the same are provided. A heat pipe having an evaporator set at one end of a tubular closed container and using heat of an outside high temperature part to cause the inside working medium to evaporate and a condenser set at the other end side of the closed container and radiating heat to an outside low temperature part to cause the evaporated working medium to condense, wherein the evaporator is arranged below the condenser and has a holding means holding the liquefied working medium condensed by the condenser along with an increase in the amount of heat received by the evaporator to prevent return to the evaporator.

1 . A heat pipe comprising 
 an evaporator provided at one end of a tubular closed container, and using heat of an outside high temperature part to cause the inside working medium to evaporate and    a condenser provided at the other end side of the closed container and radiating heat to an outside low temperature part to cause the evaporated working medium to condense, wherein    the evaporator is arranged below the condenser and has a holding means holding the liquefied working medium condensed by the condenser along with an increase in the amount of heat received by the evaporator to prevent return to the evaporator.    
   
   
       2 . A heat pipe comprising 
 an evaporator provided at one end of a tubular closed container, and using heat of an outside high temperature part to cause the inside working medium to evaporate and    a condenser provided at the other end side of the closed container and radiating heat to an outside low temperature part to cause the evaporated working medium to condense, wherein    the evaporator is arranged below the condenser and has a holding means holding the liquefied working medium condensed by the condenser when a temperature of said low temperature part becomes a predetermined value or more to prevent return to the evaporator.    
   
   
       3 . A heat pipe as set forth in  claim 1 , wherein said holding means is made a valve element provided between the evaporator and the condenser, and opening and closing a return passage of the liquefied working medium.  
   
   
       4 . A heat pipe as set forth in  claim 3 , wherein said valve element has 
 a passage through which a steam working medium evaporated by the evaporator circulates and    a dam part preventing outflow of the liquefied working medium to the passage side.    
   
   
       5 . A heat pipe as set forth in  claim 4 , wherein a height of the dam part is set higher by a predetermined amount than the level of the liquefied working medium prevented from flowing out to the passage side.  
   
   
       6 . A heat pipe as set forth in  claim 3 , wherein the valve element is driven by heat expansion and heat shrinkage of thermal wax provided at the condenser.  
   
   
       7 . A heat pipe as set forth in  claim 1 , wherein the holding means is made an area enlarging part enlarging the area of the surface of the inside wall of the condenser.  
   
   
       8 . A heat pipe as set forth in  claim 7 , wherein the area enlarging part is a wick.  
   
   
       9 . A waste heat recovery system using a heat pipe, wherein 
 an evaporator of a heat pipe as set forth in  claim 1  is arranged in an exhaust pipe for circulation of exhaust gas of an internal combustion engine,    a condenser is arranged in a cooling water passage for circulation of cooling water of the internal combustion engine, and    the heat pipe is used for transporting waste heat of the exhaust gas to the cooling water.