Abstract:
A method of controlling cooling flow through a coolant system of an internal combustion engine having an electronic control module, a cooling throttle, an EGR cooler, and an interstage cooler is provided. A pressure within a coolant system is determined. A temperature within the coolant system is determined. A temperature of exhaust gas exiting an EGR cooler is determined. A temperature of intake air exiting an interstage cooler is determined. A position of a cooling throttle within the coolant system is adjusted based upon at least one of the determined pressure within the coolant system, temperature within the coolant system, temperature of exhaust gas exiting the EGR cooler, and temperature of intake air exiting an interstage cooler being above respective predefined thresholds to adjust fluid flow within the coolant system.

Description:
TECHNICAL FIELD 
     The present disclosure relates to an engine having a coolant throttle, and more particularly to an engine having a coolant throttle that is utilized to control pressure within a cooling system to prevent damage to a radiator. 
     BACKGROUND 
     Engine coolant may be utilized to control the temperature of a variety of engine components including portions of an engine block, portions of a cylinder head, an exhaust gas recirculation (EGR) cooler, and an interstage cooler located between two compressors of the air intake system. Several of these components, such as the EGR cooler and the interstage cooler, transfer a large amount of heat into the cooling system, requiring vehicles to have higher cooling flow rates, in order to maintain appropriate operating temperatures. However, these higher cooling flow rates are only needed during certain operating conditions. Therefore, a need exists for a cooling system with a coolant throttle to control the flow rate, and therefore the pressure, within a cooling system. 
     SUMMARY 
     According to one embodiment, an engine cooling system for an internal combustion engine comprises an electronic control module, a cooling throttle, a pressure sensor, a first temperature sensor, and a second temperature sensor. The cooling throttle is positionable between an open position and a closed position. The cooling throttle is disposed in fluid communication with the cooling system. The cooling throttle controls a flow rate of coolant within the cooling system. The cooling throttle is disposed in communication with the electronic control module. The pressure sensor is disposed in fluid communication with the cooling system. The pressure sensor is disposed in communication with the electronic control module. The pressure sensor generates an output to the electronic control module. The first temperature sensor is disposed in fluid communication with the cooling system. The first temperature sensor is disposed in communication with the electronic control module. The first temperature sensor generates an output to the electronic control module. The second temperature sensor is disposed in fluid communication with exhaust gas downstream of an EGR cooler. The second temperature sensor is disposed in communication with the electronic control module. The second temperature sensor generates an output to the electronic control module. Wherein the electronic control module generates an output to adjust the position of the cooling throttle based upon at least one of the outputs of the pressure sensor, the first temperature sensor, and the second temperature sensor. 
     According to one process, a method of controlling cooling flow through a coolant system of an internal combustion engine having an electronic control module, a cooling throttle, an EGR cooler, and an interstage cooler is provided. A pressure within a coolant system is determined. A temperature within the coolant system is determined. A temperature of exhaust gas exiting an EGR cooler is determined. A temperature of intake air exiting an interstage cooler is determined. A position of a cooling throttle within the coolant system is adjusted based upon at least one of the determined pressure within the coolant system, temperature within the coolant system, temperature of exhaust gas exiting the EGR cooler, and temperature of intake air exiting an interstage cooler being above respective predefined thresholds to adjust fluid flow within the coolant system. 
     According to another process, a method of controlling cooling flow through a coolant system of an internal combustion engine having an electronic control module, a cooling throttle, an EGR cooler, and an interstage cooler is provided. A pressure within a coolant system is determined. The pressure within the coolant system is compared to a predefined coolant system pressure threshold stored within an electronic control module. A temperature within the coolant system is determined. The temperature within the coolant system is compared to a predefined coolant temperature threshold stored within the electronic control module. A temperature of exhaust gas exiting an EGR cooler is determined. The temperature of the exhaust gas exiting the EGR cooler is compared to a predefined exhaust gas temperature threshold stored within the electronic control module. A position of a cooling throttle within the coolant system is adjusted if at least one of the pressure within the coolant system exceeds the predefined coolant system pressure threshold, the temperature within the coolant system exceeds the predefined coolant temperature threshold, and the temperature of the exhaust gas exiting the EGR cooler exceeds the predefined exhaust gas temperature threshold. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing a portion of an engine cooling system for an engine having a coolant throttle to control cooling flow through the cooling system. 
         FIG. 2  is a flow chart showing one method of controlling a position of a coolant throttle. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a portion of a cooling system  10  for an internal combustion engine, the cooling system  10  having a cooling throttle  12 . The cooling throttle  12  is positionable between an open position and a closed position to regulate a flow rate of coolant within the cooling system  10 . It is contemplated that the cooling throttle may be positioned at a variety of positions between the open position and the closed position to regulate the flow arte of the cooling system  10 . The position of the cooling throttle  12  is controlled by an electronic control module (ECM). The cooling system  10  additionally comprises a pressure sensor  14 . The pressure sensor  14  is located near an inlet of a radiator  16  and is disposed in fluid communication with the cooling system  10 . The pressure sensor  14  generates an output indicative of the pressure within the cooling system  10 . The pressure sensor  14  is also disposed in communication with the ECM. The output of the pressure sensor  14  is utilized by the ECM to determine if the pressure within the cooling system  10  is above a predefined pressure limit. If the output of the pressure sensor  14  indicates that coolant within the cooling system  10  is above the predefined pressure limit, the cooling throttle  12  may be closed to reduce a coolant flow rate, and thereby reduce the pressure of the coolant within the cooling system  10 . 
     A first temperature sensor  18  is disposed in fluid communication with the cooling system  10  downstream of the radiator  16 . The radiator  16  is adapted to be positioned within an air flow when the vehicle is moving, and may additionally have a fan near the radiator  16  to pull air through the radiator, in order to transfer heat from the coolant within the cooling system  10 , to the air passing through the radiator. The first temperature sensor  18  generates an output indicative of the temperature of the coolant within the cooling system  10  after it has been cooled by the radiator  16 . The first temperature sensor  18  is also disposed in communication with the ECM. The output of the first temperature sensor  18  is utilized by the ECM to determine if the radiator  16  is reducing the temperature of the coolant to a predefined range of operating temperatures. If the output of the first temperature sensor  18  indicates that coolant within the cooling system  10  that has passed through the radiator  16  is above a predefined temperature, the cooling throttle  12  may be opened to increase a coolant flow rate, and thereby reduce the temperature of the coolant flowing past the first temperature sensor  18 . 
     The cooling system  10  additionally comprises an EGR cooler  20 . The EGR cooler  20  receives coolant within the cooling system to reduce the temperature of exhaust gas passing through the EGR cooler  20 , before that exhaust gas is fed into the air intake system of the engine to be mixed with fresh air and used for combustion. The EGR cooler  20  reduces the temperature of the exhaust gas to a level that allows the engine to function as intended. A second temperature sensor  22  is disposed in fluid communication with the exhaust gas passing through the EGR cooler. The second temperature sensor  22  is disposed downstream of the EGR cooler  20 . The second temperature sensor  22  therefore may be used to determine if the exhaust gas is being cooled sufficiently by the EGR cooler  20 , or if additional coolant flow is required through the EGR cooler  20 . The second temperature sensor  22  is disposed in communication with the ECM. The output of the second temperature sensor  22  is utilized by the ECM to determine if the EGR cooler  20  is reducing the temperature of the exhaust gas to a predefined range of operating temperatures. If the output of the second temperature sensor  22  indicates that exhaust gas that has passed through the EGR cooler  20  is above a predefined temperature, the cooling throttle  12  may be opened to increase a coolant flow rate, and thereby reduce the temperature of the coolant flowing into the EGR cooler  20 , thereby reducing the temperature of the exhaust gas flowing past the second temperature sensor  22 . 
     The cooling system  10  further comprises an interstage cooler  24 . The interstage cooler  24  receives coolant within the cooling system  10  to reduce the temperature of intake air passing through the interstage cooler  24 , before that intake air enters into a compressor  26  of a turbocharger in an air intake system of the engine. The interstage cooler  24  reduces the temperature of the intake to a level that allows the engine to function as intended. A third temperature sensor  28  is disposed in fluid communication with the intake air passing through the interstage cooler  24  and the compressor  26 . The third temperature sensor  28  is disposed downstream of the interstage cooler  24 . The third temperature sensor  24  therefore may be used to determine if the intake air is being cooled sufficiently by the interstage cooler  24 , or if additional coolant flow is required through the interstage cooler  24 . The third temperature sensor  28  is disposed in communication with the ECM. The output of the third temperature sensor  28  is utilized by the ECM to determine if the interstage cooler  24  is reducing the temperature of the exhaust gas to a predefined range of operating temperatures. If the output of the third temperature sensor  28  indicates that intake air that has passed through the interstage cooler  24  is above a predefined temperature, the cooling throttle  12  may be opened to increase a coolant flow rate, and thereby reduce the temperature of the coolant flowing into the interstage cooler  24 , thereby reducing the temperature of the intake air flowing past the third temperature sensor  28 . 
     Turning now to  FIG. 2 , a flow chart is shown depicting one process  30  of controlling the position of the cooling throttle  12 . The process  30  of controlling the position of the cooling throttle  12  is initiated as shown at block  32 . An output of the pressure sensor  14  of the cooling system  10  is compared to a predefined pressure limit value stored in the ECM at block  34 . If the pressure within the cooling system  10  is above the predefined pressure limit, the cooling throttle  12  is moved to a more closed position to reduce the flow of coolant within the cooling system  10 , and, consequently, reduce the pressure within the cooling system  10  as shown at block  36 . 
     If the pressure is not above the predefined pressure limit, the method  30  determines if the temperature of intake air exiting a compressor  26  of a turbocharger is above a first predefined temperature limit, as shown at block  38 . If the temperature of intake air exiting a compressor  26  of the turbocharger is above the first predefined temperature, the cooling throttle  12  is moved to a more open position to increase the flow of coolant through the cooling system  10  as shown at block  40 . 
     If the temperature of intake air exiting a compressor  26  is not above the first predefined temperature, a temperature of exhaust gas exiting an EGR cooler  20  is compared to a second predefined temperature, as shown at block  42 . If the temperature of exhaust gas exiting the EGR cooler  20  is above the second predefined temperature, the cooling throttle  12  is moved to a more open position, to increase the flow of coolant through the cooling system  10 , as shown at block  44 . 
     If the temperature of exhaust gas exiting the EGR cooler  20  is not above the second predefined temperature, a temperature of coolant within the cooling system  10  is compared to a third predefined temperature, as shown at block  46 . If the temperature of coolant within the cooling system  10  is above the third predefined temperature, the cooling throttle  12  is moved to a more open position, to increase the flow of coolant through the cooling system  10 , as shown at block  48 . If the temperature of the coolant is not above the third predefined temperature, the method ends, as shown at block  50 , and will be restarted at block  32  after a predefined period of time. 
     The method  30  therefore protects the cooling system  10  from operating at a pressure that is above the predefined pressure limit of the cooling system  10 , while also ensuring that if the pressure is not above the predefined pressure limit, the temperature of coolant within the cooling system  10 , the temperature of exhaust gas exiting the EGR cooler  20 , and the temperature of intake air exiting a compressor  26  of the turbocharger may be controlled by adjusting coolant flow through a coolant throttle  12  to a more open position. If the pressure of the coolant system  10  is above the predefined pressure limit, and at least one of the temperature sensors indicates a temperature above a predefined limit, engine performance may be limited to prevent damage to the engine, or the cooling system  10  of the engine.