Engine cooling system

Abstract

An engine cooling system may include a first water jacket provided in a cylinder block; a second water jacket provided in a cylinder head; a main line connected to a water pump, the first water jacket, the second water jacket, and a radiator such that a coolant discharged from the water pump passes through the first water jacket and the second water jacket to be circulated to the water pump via the radiator; the third water jacket provided in a cylinder separately from the first water jacket or the second water jacket; and a sub-line connected to the water pump and the third water jacket such that the coolant discharged from the water pump passes through the third water jacket to be directly circulated to the water pump without passing through the radiator.

What is claimed is: 
     
         1 . An engine cooling system, comprising:
 a first water jacket provided in a cylinder block;   a second water jacket provided in a cylinder head;   a first line connected to a water pump, the first water jacket, the second water jacket, and a radiator, wherein a coolant discharged from the water pump passes through the first water jacket and the second water jacket to be circulated to the water pump via the radiator;   a third water jacket provided separately from the first water jacket or the second water jacket; and   a second line connected to the water pump and the third water jacket, wherein the coolant discharged from the water pump passes through the third water jacket to be directly circulated to the water pump without passing through the radiator when the coolant is discharged along the second line.   
     
     
         2 . The engine cooling system of  claim 1 ,
 wherein the third water jacket is positioned on an exhaust side in the cylinder head.   
     
     
         3 . The engine cooling system of  claim 1 , further including:
 a bypass line connected to first and second portions of the first line to allow the coolant having passed through the first water jacket and the second water jacket to bypass the radiator and thus to be directly circulated to the water pump; and   a thermostat positioned at one of the first and second portions of the first line where the bypass line branches from the first line and controlling flow of the coolant based on temperature of the coolant such that the coolant is controlled to pass through or bypass the radiator according to the temperature of the coolant.   
     
     
         4 . The engine cooling system of  claim 1 ,
 wherein the second line is connected to an exhaust gas recirculation (EGR) cooler or heater at a position between the third water jacket and the water pump such that the coolant having passed through the third water jacket passes through the EGR cooler or heater prior to being circulated to the water pump.   
     
     
         5 . The engine cooling system of  claim 1 , further including:
 a first valve positioned at a point where the first line and the second line branch from the water pump and configured for controlling flow of the coolant supplied to each of the first line and the second line; and   a controller connected to the first valve and configured for controlling a flow rate of the coolant supplied to each of the first line and the second line by controlling an opening ratio of the first valve based on a state of an engine.   
     
     
         6 . The engine cooling system of  claim 5 , wherein the state of the engine includes a driving state of the engine or temperature of the engine. 
     
     
         7 . The engine cooling system of  claim 5 ,
 wherein, when temperature of the engine is required to be increased, the controller is configured to control the opening ratio of the first valve to increase the flow rate of the coolant supplied to the second line.   
     
     
         8 . The engine cooling system of  claim 1 , further including:
 a connection line connected to a third portion of the first line and a fourth portion of the second line;   a second valve mounted at the fourth portion where the connection line is connected to the second line and configured for controlling flow of the coolant supplied to each of the connection line and the second line; and   a controller connected to the second valve and configured for controlling an opening ratio of the second valve.   
     
     
         9 . The engine cooling system of  claim 8 , wherein the controller is configured for controlling the opening ratio of the second valve based on temperature of the coolant for controlling a flow rate of the coolant supplied to the first line through the connection line after having passed through the third water jacket through the second line. 
     
     
         10 . The engine cooling system of  claim 9 ,
 wherein, when the temperature of the coolant is equal to or less than a predetermined temperature, the controller is configured to control the opening ratio of the second valve to block the coolant supplied from the second line to the first line through the connection line.   
     
     
         11 . The engine cooling system of  claim 9 ,
 wherein, when the temperature of the coolant is greater than a predetermined temperature, the controller is configured to control the opening ratio of the second valve with a maximum opening ratio to supply the coolant having passed through the third water jacket through the second line to the first line.