Engine Cooling Apparatus and Engine Cooling Method

Abstract

A sub-control valve is provided which detects a temperature of a liquid coolant in a main circulation path and separates part of the liquid coolant which is to be sent to a main radiator to send it into a sub-circulation path in case the detected temperature of the liquid coolant exceeds an upper limit value of the temperature of the liquid coolant when an engine runs in a steady state, and the liquid coolant which is sent into the sub-circulation path by the sub-control valve is cooled in a sub-radiator and is then caused to flow into a cooler device, while the liquid coolant in the sub-circulation path is separated to be returned to an upstream side of a first pump in the main circulation path.

1 . An engine cooling apparatus comprising:
 a main radiator configured to cool a liquid coolant which flows through an interior of an engine;   a main circulation path for a liquid coolant which circulates through the engine and the main radiator;   a first pump provided upstream of the engine along the main circulation path, the first pump configured to drive the liquid coolant to flow;   a sub-radiator which is independent of the main circulation path, the sub-radiator configured to cool a liquid coolant used in a cooler device for cooling an onboard heater element;   a sub-circulation path for the liquid coolant which circulates through the cooler device and the sub-radiator;   a second pump provided in a halfway position along the sub-circulation path, the second pump configured to drive the liquid coolant in the sub-circulation path to flow; and   a sub-control valve configured to detect a temperature of the liquid coolant in the main circulation path and configured to separate part of the liquid coolant which is sent to the main circulation path to be sent to the sub-circulation path in case the detected temperature exceeds an upper limit value of the temperature of the liquid coolant when the engine runs in a steady state, wherein:   the liquid coolant which is sent to the sub-circulation path by the sub-control valve is cooled by the sub-radiator to thereafter be caused to flow into the cooler device; and part of the liquid coolant in the sub-circulation path is separated to be returned to an upstream side of the first pump in the main circulation path.   
     
     
         2 . The engine cooling apparatus according to  claim 1 , further comprising
 a main control valve configured to detect a temperature of the liquid coolant in the main circulation path, configured to return the liquid coolant, which has passed through the engine, to the engine to warm up the engine in case the detected temperature is less than a lower limit value of the temperature of the liquid coolant when the engine runs in the stead state, and configured to send part or all of the liquid coolant which has passed through the engine towards the main radiator in the main circulation path in case the detected temperature is equal to or more than the lower limit value.   
     
     
         3 . The engine cooling apparatus according to  claim 1 , wherein
 the lower limit value of the temperature of the liquid coolant when the engine runs in the steady state is set to 80° C. and the upper limit value thereof is set to 100° C.   
     
     
         4 . The engine cooling apparatus according to  claim 1 , wherein
 the lower limit value of the temperature of the liquid coolant when the engine runs in the steady state is set to any value in the range of 70° C. to 90° C. and the upper limit value thereof is set to any value in the range of 90° C. to 120° C.   
     
     
         5 . The engine cooling apparatus according to  claim 1 , further comprising
 a bypass circulation path configured to send the liquid coolant which is separated by the sub-control valve to an upstream side or a downstream side of the second pump.   
     
     
         6 . The engine cooling apparatus according to  claim 1 , further comprising
 an EGR cooler provided in a branched circulation path which branches off the main circulation path to allow the separated liquid coolant to flow therethrough.   
     
     
         7 . The engine cooling apparatus according to  claim 1 , further comprising
 an EGR cooler provided in a halfway position along the sub-circulation path.   
     
     
         8 . An engine cooling method by using the engine cooling apparatus according to  claim 1 , comprising:
 sending part of the liquid coolant in the main circulation path to the sub-circulation path;   cooling the cooled liquid coolant by the sub-radiator; and   returning the cooled liquid coolant to the main circulation path in a position lying at an upstream side of the engine.