Cooling system for internal combustion engine, and control method thereof

Abstract

The present invention provides a cooling system for an internal combustion engine, comprising: a flow channel switching valve for switching between a plurality of cooling water channels at least including a heater line for air heating, a block line for cooling an engine block, and a transmission line for an oil warmer of a transmission so as to sequentially open at least one of the plurality of cooling water channels in accordance with a warm-up state of the internal combustion engine; and a control device for controlling opening and closing of the flow channel switching valve so as to restrict a cooling water distribution rate of the heater line. The cooling system allows acceleration of cooling water temperature recovery from a temporary drop.

The invention claimed is: 
     
       1. A cooling system for an internal combustion engine, comprising:
 a flow channel switching valve including a stator having an outlet port and a plurality of inlet ports corresponding one to one to a plurality of cooling water channels at least including a heater line for air heating, a block line for cooling an engine block, and a transmission line for an oil warmer of a transmission, and a rotor having flow channels therein and rotatably fitted in the stator, the flow channel switching being configured to sequentially open at least one of the plurality of cooling water channels in accordance with a warm-up state of the internal combustion engine; and 
 a control device configured to control opening and closing of the flow channel switching valve by adjusting a rotation angle of the rotor of the flow channel switching valve, 
 wherein the flow channels of the rotor of the flow channel switching valve are formed so as to allow opening areas of the inlet ports corresponding to the heater line and the transmission line to change as a rotation angle of the rotor changes, such that, when the transmission line opens, a cooling water distribution rate of the heater line is restricted while a flow rate of cooling water through the transmission line is maintained unchanged. 
 
     
     
       2. The cooling system for the internal combustion engine according to  claim 1 , wherein the control device controls an electric water pump to restrict a discharge flow rate of the electric water pump for supplying cooling water to the plurality of cooling water channels. 
     
     
       3. The cooling system for the internal combustion engine according to  claim 1 , wherein the control device controls the opening and closing of the flow channel switching valve so as to change a flow rate of cooling water through the heater line by acquiring various information on an air conditioning system including temperature information from temperature sensors installed at different locations in a vehicle and calculating the rotation angle of the rotor based on comparison between the acquired information and a stored template for correcting the flow rate. 
     
     
       4. A method for controlling a cooling system for an internal combustion engine, the cooling system including a flow channel switching valve including a stator having an outlet port and a plurality of inlet ports corresponding one to one to a plurality of cooling water channels at least including a heater line for air heating, a block line for cooling an engine block, and a transmission line for an oil warmer of a transmission, and a rotor having flow channels therein and rotatably fitted in the stator, the flow channel switching being configured to sequentially open at least one of the plurality of cooling water channels in accordance with a warm-up state of the internal combustion engine; and a control device, the method causing the control device to control opening and closing of the flow channel switching valve so as to control cooling water distribution rates of the plurality of cooling water channels,
 wherein the flow channels in the rotor of the flow channel switching valve are formed so as to allow opening areas of the inlet ports corresponding to the heater line and the transmission line to change as the rotation angle of the rotor changes, and 
 wherein, when the transmission line opens, the control device restricts a cooling water distribution rate of the heater line while maintaining a flow rate of cooling water through the transmission line unchanged, by adjusting a rotation angle of the rotor of the flow channel switching valve.