Cooling system for piston of internal combustion engine

Abstract

A cooling system for a piston of an internal combustion engine includes a cooling channel ( 34 ) designed as an oil passage embedded in the piston and arranged adjacent to a top ring groove, and an oil supply portion ( 8 ) that supplies oil to the cooling channel. An amount of oil supplied from the oil supply portion to the cooling channel is made larger when an amount of heat generated in a combustion chamber is large than when the amount of heat generated in the combustion chamber is small.

1 . A cooling system for a piston of an internal combustion engine, comprising:
 a piston that includes a top ring groove provided in an outer peripheral face of the piston and fitted with a top ring, and a cooling channel designed as an oil passage embedded in the piston and located adjacent to the top ring groove;   an oil supply portion that supplies oil to the cooling channel; and   a control portion that increases an amount of oil supplied from the oil supply portion to the cooling channel as an amount of heat generated in a combustion chamber increases.   
     
     
         2 . The cooling system for the piston of the internal combustion engine according to  claim 1 , wherein the control portion stops supplying oil from the oil supply portion to the cooling channel when the amount of heat generated in the combustion chamber is equal to or smaller than a predetermined lower limit. 
     
     
         3 . The cooling system for the piston of the internal combustion engine according to  claim 1 , wherein the control portion increases the amount of oil supplied from the oil supply portion to the cooling channel as an amount of fuel injection increases. 
     
     
         4 . The cooling system for the piston of the internal combustion engine according to  claim 1 , wherein the control portion increases the amount of oil supplied from the oil supply portion to the cooling channel as an engine speed and an engine load increase. 
     
     
         5 . The cooling system for the piston of the internal combustion engine according to any one of  claims 1  to  4 , wherein the cooling channel is so formed as to be located adjacent to the top ring groove and a second land. 
     
     
         6 . The cooling system for the piston of the internal combustion engine according to  claim 5 , wherein the piston is further equipped with a second ring groove located directly below the top ring groove, and
 the second land is provided between the top ring groove and the second ring groove.   
     
     
         7 . The cooling system for the piston of the internal combustion engine according to any one of  claims 1  to  6 , wherein the control portion makes the amount of oil supplied from the oil supply portion to the cooling channel larger when the internal combustion engine is being warmed up than when the internal combustion engine includes been warmed up, for an equivalent engine load and an equivalent engine speed. 
     
     
         8 . The cooling system for the piston of the internal combustion engine according to any one of  claims 1  to  7 , wherein the control portion prohibits the oil supply portion from being stopped when a temperature of coolant is equal to or higher than a predetermined upper-limit coolant temperature or when a temperature of oil is equal to or higher than a predetermined upper-limit oil temperature. 
     
     
         9 . The cooling system for the piston of the internal combustion engine according to any one of  claims 1  to  8 , wherein the oil supply portion is an oil jet. 
     
     
         10 . The cooling system for the piston of the internal combustion engine according to any one of  claims 1  to  9 , wherein the top ring groove and the cooling channel are annular. 
     
     
         11 . A method of controlling a cooling system for a piston of an internal combustion engine, comprising:
 providing a piston that includes a top ring groove provided in an outer peripheral face of the piston and fitted with a top ring, and a cooling channel designed as an oil passage embedded in the piston and located adjacent to the top ring groove, and an oil supply portion that supplies oil to the cooling channel; and   making an amount of oil supplied from the oil supply portion to the cooling channel larger when an amount of heat generated in a combustion chamber is large than when the amount of heat generated in the combustion chamber is small.   
     
     
         12 . The method of controlling the cooling system for the piston of the internal combustion engine according to  claim 11 , wherein the amount of oil supplied from the oil supply portion to the cooling channel is made larger when the internal combustion engine is being warmed up than when the internal combustion engine includes been warmed up, for an equivalent engine load and an equivalent engine speed.