Exhaust valve for engine

Abstract

An exhaust valve for an engine which discharges an exhaust gas generated in a combustion chamber of the engine may include an adiabatic coating layer having a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a face portion of the exhaust valve coming into contact with a flame.

What is claimed is: 
     
         1 . An exhaust valve for an engine, which discharges an exhaust gas generated in a combustion chamber of the engine comprising:
 an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a face portion of the exhaust valve coming into contact with a flame.   
     
     
         2 . An exhaust valve for an engine, which discharges an exhaust gas generated in a combustion chamber of the engine, comprising an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a neck portion of the exhaust valve coming into contact with the exhaust gas. 
     
     
         3 . An exhaust valve for an engine, which discharges an exhaust gas generated in a combustion chamber of the engine, comprising an adiabatic coating layer including a polyamideimide resin and an aerogel dispersed in the polyamideimide resin and having thermal conductivity of 0.60 W/m or less formed on a face portion of the exhaust valve coming into contact with a flame and a neck portion of the exhaust valve coming into contact with the exhaust gas. 
     
     
         4 . The exhaust valve for the engine of  claim 1 , wherein the adiabatic coating layer has a thermal capacity of 1,250 KJ/m 3  K or less. 
     
     
         5 . The exhaust valve for the engine of  claim 1 , wherein the polyamideimide resin exists in a content of 2 wt % or less in the aerogel. 
     
     
         6 . The exhaust valve for the engine of  claim 1 , wherein the polyamideimide resin does not exist at a depth corresponding to 5% or more of a longest diameter from a surface of the aerogel. 
     
     
         7 . The exhaust valve for the engine of  claim 1 , wherein each aerogel has porosity of 92% to 99% while being dispersed in the polyamideimide resin. 
     
     
         8 . The exhaust valve for the engine of  claim 1 , wherein the adiabatic coating layer has a thickness of 50 μm to 500 μm. 
     
     
         9 . The exhaust valve for the engine of  claim 1 , wherein the adiabatic coating layer includes 5 to 50 parts by weight of the aerogel based on 100 parts by weight of the polyamideimide resin. 
     
     
         10 . The exhaust valve for the engine of  claim 2 , wherein the adiabatic coating layer has a thermal capacity of 1,250 KJ/m 3  K or less. 
     
     
         11 . The exhaust valve for the engine of  claim 2 , wherein the polyamideimide resin exists in a content of 2 wt % or less in the aerogel. 
     
     
         12 . The exhaust valve for the engine of  claim 2 , wherein the polyamideimide resin does not exist at a depth corresponding to 5% or more of a longest diameter from a surface of the aerogel. 
     
     
         13 . The exhaust valve for the engine of  claim 2 , wherein each aerogel has porosity of 92% to 99% while being dispersed in the polyamideimide resin. 
     
     
         14 . The exhaust valve for the engine of  claim 2 , wherein the adiabatic coating layer has a thickness of 50 μm to 500 μm. 
     
     
         15 . The exhaust valve for the engine of  claim 2 , wherein the adiabatic coating layer includes 5 to 50 parts by weight of the aerogel based on 100 parts by weight of the polyamideimide resin. 
     
     
         16 . The exhaust valve for the engine of  claim 3 , wherein the adiabatic coating layer has a thermal capacity of 1,250 KJ/m 3  K or less. 
     
     
         17 . The exhaust valve for the engine of  claim 3 , wherein the polyamideimide resin exists in a content of 2 wt % or less in the aerogel. 
     
     
         18 . The exhaust valve for the engine of  claim 3 , wherein the polyamideimide resin does not exist at a depth corresponding to 5% or more of a longest diameter from a surface of the aerogel. 
     
     
         19 . The exhaust valve for the engine of  claim 3 , wherein each aerogel has porosity of 92% to 99% while being dispersed in the polyamideimide resin. 
     
     
         20 . The exhaust valve for the engine of  claim 3 , wherein the adiabatic coating layer has a thickness of 50 μm to 500 μm and wherein the adiabatic coating layer includes 5 to 50 parts by weight of the aerogel based on 100 parts by weight of the polyamideimide resin.