METHOD FOR CONTROLLING AN INLET TEMPERATURE TO PROTECT AN INLET MANIFOLD

Abstract

Engine control procedure for a vehicle, which includes the following: a temperature (208) of a gas in an intake manifold (14) of an engine (8) is determined; a temperature (272) of a metal exhaust gas recirculation (EGR) line is determined at a location where the EGR line is coupled to the intake manifold (14); and an opening of an EGR valve (30) is reduced when the temperature (208) of the gas or the temperature (272) of the line is greater than a predetermined temperature; and the opening of the EGR valve (30) is reduced until the temperature (208) of the gas and the temperature (272) of the line are lower than a second predetermined temperature, which is lower than the predetermined temperature, for a predetermined period of time.

Description

AREA

[0001] The present disclosure relates to internal combustion engines and, more particularly, to methods for controlling an intake temperature. BACKGROUND

[0002] An engine burns air and fuel to produce torque. The air flows into the engine through an intake system. The intake system may include a throttle valve and an intake manifold. Fuel is delivered through one or more fuel injectors. The engine outputs the torque to a transmission. The transmission transfers the torque to one or more wheels. The exhaust resulting from combustion is expelled from the engine into an exhaust system.

[0003] An exhaust gas recirculation (EGR) system recirculates exhaust gas back to the intake system. For the exhaust gas to flow back to the intake system, the pressure in the exhaust system must be greater than the pressure where the exhaust gas enters the intake system. The EGR system can be controlled to deliver a target mixture of exhaust gas, air, and fuel to each cylinder.

[0004] DE 10 2005 001 961 A1 describes an engine control method in which the temperature of a gas in an intake area of ​​an engine is determined and an opening of an exhaust gas recirculation valve is adjusted in such a way that a maximum temperature at a predeterminable point in the intake area is not exceeded.

[0005] DE 695 20 942 T2 describes a method for controlling a diesel engine with exhaust gas recirculation, to which a suitable amount of oxygen is supplied for fuel combustion. The aim is to protect exhaust gas recirculation components from excessive temperatures.

[0006] DE 103 19 333 A1 describes an engine control method with which an intake temperature in a combustion chamber of an internal combustion engine is influenced by means of exhaust gas recirculation and an exhaust gas cooler.

[0007] DE 10 2011 076 026 A1 describes a cooled exhaust gas recirculation system for heating the coolant during a cold engine start.

[0008] EP 2 038 528 B1 describes a cooler arrangement for an internal combustion engine with exhaust gas recirculation.

[0009] An object of the invention is to provide an engine control method which, on the one hand, prevents damage to an intake manifold due to an excessively high temperature of a gas therein and, on the other hand, does not unnecessarily restrict the effectiveness of exhaust gas recirculation. SUMMARY

[0010] This object is achieved by an engine control method having the features of claim 1.

[0011] The engine control method is provided for a vehicle and includes: determining a temperature of a gas in an intake manifold of an engine; determining a temperature of a metal exhaust gas recirculation (EGR) passage at a location where the EGR passage is coupled to the intake manifold; and decreasing an opening of an EGR valve when the temperature of the gas and the temperature of the passage are greater than a predetermined temperature. Further, the opening of the EGR valve is decreased until the temperature of the gas and the temperature of the passage are less than a second predetermined temperature, which is less than the predetermined temperature, for a predetermined period of time.

[0012] According to further features, the predetermined temperature corresponds to a melting temperature of the intake manifold.

[0013] In still further features, the engine control method further comprises reducing the opening of the EGR valve to a predetermined opening when the temperature of the gas and the temperature of the conduit are greater than the predetermined temperature.

[0014] In still further features, the engine control method further comprises fully closing the EGR valve when the temperature of the gas and the temperature of the conduit are greater than the predetermined temperature.

[0015] According to further features, the engine control method further comprises reducing the opening of the EGR valve when the temperature of the gas and the temperature of the conduit are greater than the predetermined temperature for a predetermined period of time.

[0016] According to further features, the engine control method further comprises, when the temperature of the gas and / or the temperature of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature, turning on an electric coolant pump and / or increasing a speed of the electric coolant pump.

[0017] According to still further features, the engine control method further comprises opening an electric thermostat valve when the temperature of the gas and / or the temperature of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature.

[0018] According to still further features, the engine control method further comprises opening aerodynamic flaps of the vehicle when the temperature of the gas and / or the temperature of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a functional block diagram of an exemplary engine system according to the present disclosure; Fig. 2 is a functional block diagram of an exemplary engine control system according to the present disclosure; Fig. 3 is a functional block diagram of an exemplary temperature reduction module according to the present disclosure; Fig. 4 is a flowchart illustrating an exemplary method for controlling intake manifold temperatures according to the present disclosure; and Fig. 5 is a flowchart illustrating an example method for disabling a reduction in exhaust gas recirculation commanded to reduce intake manifold temperatures, according to the present disclosure.

[0020] Reference numerals may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0021] An engine burns air and fuel in cylinders to produce driving torque for a vehicle. The engine draws air into the cylinders through an intake system. The intake system includes a throttle valve and an intake manifold. The engine releases the exhaust gas resulting from combustion into an exhaust system. An exhaust gas recirculation (EGR) system recirculates exhaust gas from the exhaust system back to an intake system, such as the intake manifold.

[0022] To reduce mass, the intake manifold may include one or more plastics. However, under certain circumstances, the intake manifold may experience high temperatures, and the intake manifold may melt and / or lose its structural integrity. For example, the intake manifold may experience high temperatures when the ambient air is hot, under high engine load conditions, and / or when the efficiency of a cooler (e.g., a charge cooler and / or an EGR cooler) decreases. For example, the efficiency of a cooler may decrease when the flow of a cooling medium (e.g., coolant and / or air) through the cooler is low or zero.

[0023] An engine control module (ECM) of the present disclosure estimates a temperature of a gas in the intake manifold. The ECM also estimates a temperature of a metal EGR line connected to the intake manifold. The ECM reduces EGR flow when the temperature of the gas and / or the temperature of the EGR line are greater than a predetermined temperature, above which the intake manifold may melt and / or be damaged. The ECM may also selectively take one or more other remedial actions to reduce the temperature of the gas and the temperature of the EGR line, for example, by increasing a speed of an electric coolant pump, opening an electric thermostat valve, and / or opening aerodynamic flaps.

[0024] Now on Fig. Referring to Figure 1, a functional block diagram of an exemplary engine system 10 is shown. Although the engine system 10 is discussed in terms of a spark-ignition engine system, the present application is also applicable to other types of engine systems, such as compression-ignition engine systems and hybrid engine systems.

[0025] Air is drawn into an engine 8 through an intake system that includes a throttle valve 12 and an intake manifold 14. The throttle valve 12 can regulate the airflow into the intake manifold 14. The intake manifold 14 includes or is made of one or more plastics. A throttle actuator module 16 controls the actuation of the throttle valve 12. The engine 8 combusts an air / fuel mixture in cylinders of the engine 8. A fuel system 17 selectively injects fuel into the engine 8. An ignition system 19 selectively provides an ignition spark for combustion to the engine 8.

[0026] Combustion of the air / fuel mixture drives a crankshaft and produces exhaust gas. The engine 8 discharges the exhaust gas to an exhaust manifold 18. One or more exhaust treatment devices, such as a catalyst, may react with various components of the exhaust gas. For example only, the catalyst may include a three-way catalyst (TWC), a catalytic converter, or another suitable type of catalyst.

[0027] Some engine systems, such as the exemplary engine system of Fig. 1, include a turbocharger. The turbocharger includes a turbine 20 and a compressor 22. Exhaust gas discharged by the engine 8 drives the rotation of the turbine 20. The turbine 20 and the compressor 22 are mechanically coupled such that the turbine 20 drives the rotation of the compressor 22. The compressor 22 pressurizes air, which is supplied to the intake manifold 14. Some engine systems may include multiple (e.g., two) turbochargers.

[0028] A turbine bypass valve 24 controls exhaust flow bypassing the turbine 20. A boost actuator module 26 controls the turbine bypass valve 24. Exhaust bypassing the turbine 20 reduces exhaust flow through the turbine 20, thereby reducing the output of the compressor 22. In various implementations, a wastegate valve may be implemented in place of the turbine bypass valve 24.

[0029] A charge cooler 28, such as a charge air cooler (CAC) or an intercooler, cools the air output from the compressor 22. For example, a CAC transfers heat from the air output from the compressor 22 to the air flowing through the CAC. An intercooler transfers heat from the air output from the compressor 22 to a coolant, such as engine coolant, flowing through the intercooler. The charge cooler 28 may be omitted in some engine systems that have one or more turbochargers. In engine systems without a turbocharger, the turbine 20, the compressor 22, the turbine bypass valve 24, and the charge cooler 28 may be omitted.

[0030] An EGR valve 30 recirculates exhaust gas to the intake system, such as the intake manifold 14. The exhaust gas may be recirculated to another suitable location in the intake system, for example, upstream of the compressor 22. An EGR actuator module 32 controls the EGR valve 30. An EGR cooler 34 may be implemented to cool the exhaust gas recirculated to the intake system. A cooler bypass system (not shown) including an EGR cooler bypass valve may be implemented to control the exhaust gas bypassing the EGR cooler 34. The conduit through which the exhaust gas is recirculated to the intake system comprises metal due to the high temperatures of the exhaust gas.

[0031] An engine control module (ECM) 40 regulates the operation of the engine system 10. For example, the ECM 40 controls the opening of the throttle valve 12 via the throttle actuator module 16, the opening of the EGR valve 30 via the EGR actuator module 32, an amount and timing of fuel injection via the fuel system 17, spark timing via the ignition system 19, and an output of a turbocharger via the boost actuator module 26. The ECM 40 may also control the operation of the intake and exhaust valve actuators and / or one or more other suitable engine actuators.

[0032] The ECM 40 communicates with various sensors, such as a manifold absolute pressure (MAP) sensor 50, a crankshaft position sensor 52, a coolant temperature sensor 54, an ambient air temperature sensor 56, and an exhaust gas temperature sensor 57. The MAP sensor 50 generates a MAP signal indicative of absolute pressure within the intake manifold 14. The crankshaft position sensor 52 generates a signal based on crankshaft rotation. Engine speed in revolutions per minute (RPM) can be determined based on the crankshaft rotation.

[0033] The engine coolant temperature sensor 54 generates a coolant temperature signal indicative of a temperature of the engine coolant, such as a temperature of the coolant at a coolant outlet of the engine 8. The ambient air temperature sensor 56 generates an air temperature signal based on an ambient air temperature. The exhaust gas temperature sensor 57 generates an exhaust gas temperature signal based on an exhaust gas temperature.

[0034] The engine system 10 may also include one or more other sensors 58. The other sensors 58 may include, for example, a mass air flow (MAF) sensor, a charge cooler outlet temperature sensor, an EGR cooler outlet temperature sensor, an oil temperature sensor, an intake air temperature sensor, and / or other suitable types of sensors.

[0035] Now on Fig. 2, a functional block diagram of an example implementation of the ECM 40 is shown. A torque request module 102 determines a torque request 104 based on one or more driver inputs 106, such as an accelerator pedal position, a brake pedal position, a cruise control input, and / or one or more other suitable driver inputs. The torque request module 102 may additionally or alternatively determine the torque request 104 based on one or more other torque requests, such as based on torque requests generated by the ECM 40 and / or based on torque requests received from other modules of the vehicle, such as a transmission control module, a hybrid control module, a chassis control module, etc.

[0036] One or more engine actuators may be controlled based on the torque request 104 and / or based on one or more other vehicle operating parameters. For example, a throttle control module 112 may determine a target throttle opening 116 based on the torque request 104. The throttle actuator module 16 adjusts the opening of the throttle valve 12 based on the target throttle opening 116. A spark control module 120 may determine a target spark timing 124 based on the torque request 104. The ignition system 19 generates an ignition spark based on the target spark timing 124.

[0037] A fuel control module 128 may determine one or more target fueling parameters 132 based on the torque request 104. For example, the target fueling parameters 132 may include a number of fuel injection pulses (per combustion event), a timing for each pulse, and an amount for each pulse. The fuel system 17 injects fuel based on the target fueling parameters 132.

[0038] A boost control module 136 may determine a target boost pressure 140 based on the torque request 104. The boost actuator module 26 adjusts an opening of the turbine bypass valve 24 based on the target boost pressure 140 to cause the compressor 22 to reach the target boost pressure 140. An EGR control module 144 may determine a target EGR opening 148 based on the torque request 104. The EGR actuator module 32 adjusts an opening of the EGR valve 30 based on the target EGR opening 148.

[0039] Under certain circumstances, a temperature reduction module 152 (see also Fig. 3) a first temperature reduction command 156 to reduce one or more temperatures of the intake manifold 14. For example, the temperature reduction module 152 may generate the first temperature reduction command 156 when an intake manifold temperature is greater than a predetermined temperature. The intake manifold 14 may melt and / or lose its structural integrity if the intake manifold temperature is greater than the predetermined temperature.

[0040] Now on Fig. 3, a functional block diagram of an example implementation of the temperature reduction module 152 is shown. A gas temperature module 204 determines an intake gas temperature (intake manifold gas temperature) 208. The intake gas temperature 208 may correspond to a temperature of the mixture of gases in the intake manifold 14.

[0041] For non-turbocharged engines, the gas temperature module 204 determines the intake gas temperature 208 based on an ambient temperature 212, an EGR cooler outlet temperature 216, and an EGR mass fraction 220. For example, the gas temperature module 204 may determine the intake gas temperature 208 using the equation: IM Gas Temp=EGR Cooler Out Temp*EGR Mass Fraction+Amb Temp*(1−EGR Mass Fraction) where IM Gas Temp is the intake gas temperature 208, EGR Cooler Out Temp is the EGR cooler outlet temperature 216, Amb Temp is the ambient temperature 212, and EGR Mass Fraction is the EGR mass fraction 220. The ambient temperature 212 may be measured using the ambient air temperature sensor 56. The EGR cooler outlet temperature 216 may be measured or determined using a sensor, as discussed further below. The EGR mass fraction 220 may be a value between 0.0 and 1.0 (corresponding to 0% and 100%) and may be determined as discussed further below.

[0042] An EGR cooler temperature module 224 may determine the EGR cooler outlet temperature 216. The EGR cooler outlet temperature 216 may refer to a temperature at an outlet of the EGR cooler 34. The EGR cooler temperature module 224 may determine the EGR cooler outlet temperature 216 based on an exhaust gas temperature 228, a coolant temperature 232, and an efficiency of the EGR cooler 34. For example, the EGR cooler temperature module 224 may determine the EGR cooler outlet temperature 216 using the equation: EGR Cooler Out Temp=Exh Temp−Cooler Eff*(Exh Temp−Coolant Temp), where EGR Cooler Out Temp is the EGR cooler outlet temperature 216, Exh Temp is the exhaust gas temperature 228, Cooler Eff is the efficiency of the EGR cooler 34, and Coolant Temp is the coolant temperature 232. The exhaust gas temperature 228 may be measured, for example, using the exhaust gas temperature sensor 57 or determined based on one or more other parameters. The coolant temperature 232 may be measured, for example, using the coolant temperature sensor 52. The EGR cooler efficiency may be initially set to a predetermined maximum value (e.g., to approximately 1.0), and the EGR cooler temperature module 224 may selectively decrease the EGR cooler efficiency over time as the EGR cooler 34 ages.

[0043] An EGR determination module 236 determines the EGR mass fraction 220. The EGR mass fraction 220 may correspond to an expected mass fraction of EGR relative to the (total) mass of a gas charge of a future (e.g., next) combustion event of the engine 8 or a mass fraction of EGR relative to the total mass of gas in the intake manifold 14.

[0044] The EGR determination module 236 may determine a steady-state EGR flow rate (SS EGR flow rate). The SS EGR flow rate corresponds to a mass flow rate of EGR back to the intake manifold 14 under SS EGR conditions. The SS EGR conditions may refer to times when the SS EGR flow rate varies by less than a predetermined amount over a predetermined period of time.

[0045] The EGR determination module 236 may determine the SS EGR flow rate using the relationship: m˙EGR=CD*AT*pOR*TO*(pTpO)1γ*{2*γγ−1*[1−(pTpO)(γ−1γ)]}12 where (ṁ EGR ) is the (instantaneous) mass flow rate of the EGR back to the engine 8 by means of the EGR system (ie the SS EGR flow rate), and it is a function of the opening area (A T ) 240 of the EGR valve 30, a pressure (p o ) upstream of the EGR valve 30, a temperature (T o ) (e.g. the exhaust gas temperature 228), a pressure (p r ) downstream of the EGR valve 30 (e.g. a pressure 244 in the intake manifold 14) and various constants (C D , R, y).

[0046] This relationship may be embodied as an equation, such as the equation above, or as a map (e.g., a lookup table) that relates the above parameters to the SS EGR flow rate. The pressure 244 in the intake manifold 14 may be measured using the MAP sensor 50. An EGR position sensor may measure a position of the EGR valve 30, and the opening area 240 of the EGR valve 30 may be determined based on the position of the EGR valve 30.

[0047] For each combustion event of engine 8, a gas charge is drawn into a cylinder. The gas charge may include ambient air drawn through throttle valve 12; and exhaust gas recirculated via the EGR system. The gas charge may also include one or more other gases, such as fuel vapor supplied by a fuel vapor purge system (not shown).

[0048] The EGR determination module 236 determines an SS-EGR fraction for a next combustion event of the engine 8. The SS-EGR fraction corresponds to a mass fraction of EGR under SS-EGR conditions relative to the mass of the gas charge of the next combustion event of the engine 8. The EGR determination module 236 determines the SS-EGR fraction for the next combustion event based on the SS-EGR flow rate and a mass air flow rate (MAF) 248 into the intake manifold 14. The MAF 248 may be measured using a MAF sensor. The EGR determination module 236 may determine the SS-EGR fraction for the next combustion event, for example, using the equation: SSFraction=m˙EGRm˙EGR+m˙MAF where SSFraction is the SS-EGR fraction, and it is a function of the SS-EGR flow rate (ṁ EGR ) and the MAF (ṁ MAF ) 248.

[0049] The EGR determination module 236 may include a circular buffer, a first-in-first-out (FIFO) buffer, a shift register, etc. The EGR determination module 236 includes a predetermined number of the most recently determined values ​​of the SS EGR fraction. Each time the SS EGR fraction is determined, the EGR determination module 236 stores the SS EGR fraction and removes an oldest stored value of the SS EGR fraction.

[0050] The EGR determination module 236 determines the EGR mass fraction 220 for the next combustion event of the engine 8 based on a plurality of stored SS EGR fraction values. The EGR determination module 236 may determine the EGR mass fraction 220 for the next combustion event based on an average, such as a weighted average, of a plurality of stored SS EGR fraction values. The SS EGR fraction values ​​used to determine the EGR mass fraction 220 may be the most recently determined / stored values.

[0051] The EGR determination module 236 may determine the EGR mass fraction 220 for the next combustion event, for example, using the equation: EGRFraction=(∑i−0t−d(t−d−i)*SSFract−l−i)(∑i−0t−d(t−d−i)) where EGRFraction is the EGR mass fraction 220, t is a number of combustion events between a combustion event of the engine 8 and a later combustion event at which the EGR mass fraction 220 will reach a steady state (and therefore equal to the SS EGR fraction) after an EGR transient condition occurs, d is a number of combustion events between a combustion event at which a command is generated causing an EGR transient condition and a later combustion event at which the EGR mass fraction 220 will begin to change in response to the command, and where SSFrac refers to the one of the stored values ​​of the SS EGR fraction for the combustion event prior to t-1-i combustion events. t and d are integers, and d is less than t.For example, an EGR transient condition may occur in response to changes in the opening of the throttle valve 12, in response to changes in the opening of the EGR valve 30, in response to changes in the pressure in the intake manifold 14, or in response to another suitable event that causes a change in the mass flow rate of EGR back to the intake system.

[0052] In various implementations, t and d may be constant values ​​calibrated based on physical factors such as cylinder volume, the volume of intake manifold 14, and the volume of the EGR system through which the exhaust gas moves as it is recirculated. In various implementations, t and / or d may be variable values ​​and may be determined by the EGR determination module 236. The EGR determination module 236 may determine t and / or d, for example, using one or more functions or maps that relate an engine load parameter, such as an air volume per cylinder (APC), and / or the engine speed 252 to t and / or d.The one or more functions or maps are calibrated based on physical factors, such as cylinder volume, intake manifold 14 volume, and EGR system volume.

[0053] For engine systems with a turbocharger, such as the exemplary engine system of Fig. 1, the gas temperature module 204 may determine the intake gas temperature 208 based on the EGR cooler outlet temperature 216, a charge cooler outlet temperature 256, and the EGR mass fraction 220. For example, the gas temperature module 204 may determine the intake gas temperature 208 using the equation: IM Gas Temp=EGR Cooler Out Temp*EGR Mass Fraction+Charge Cooler Out Temp*(1−EGR Mass Fraction) where Im Gas Temp is the intake gas temperature 208, EGR Cooler Out Temp is the EGR cooler outlet temperature 216, Charge Cooler Outlet Temp is the charge cooler outlet temperature 256, and EGR Mass Fraction is the EGR mass fraction 220. The charge cooler outlet temperature 256 may be measured or determined using a sensor, as discussed further below. The charge cooler outlet temperature 256 may correspond to a temperature at an outlet of the charge cooler 28.

[0054] A charge cooler temperature module 260 may determine the charge cooler outlet temperature 256. For engine systems where the charge cooler 28 is an intercooler, the charge cooler temperature module 260 may determine the charge cooler outlet temperature 256 based on a compressor outlet temperature 264, the coolant temperature 232, and an intercooler efficiency. For example, the charge cooler temperature module 260 may determine the charge cooler outlet temperature 256 for an engine system including an intercooler using the equation: Charge Cooler Out Temp =Comp Out Temp−Charge Cooler Eff*(Com Out Temp −Coolant Temp) where Charge Cooler Out Temp is the charge cooler outlet temperature 256, Comp Out Temp is the compressor outlet temperature 264, Coolant Temp is the coolant temperature 232, and Charge Cooler Eff is the intercooler efficiency. The charge cooler efficiency may initially be set to a predetermined maximum value (e.g., approximately 1.0), and the charge cooler temperature module 260 may selectively decrease the charge cooler efficiency over time as the intercooler ages. The compressor outlet temperature 264 may be measured, for example, using a sensor. The compressor outlet temperature 264 may correspond to a temperature at an outlet of the compressor 22.

[0055] For engine systems where the charge cooler 28 is a charge air cooler (CAC), the charge cooler temperature module 260 may determine the charge cooler outlet temperature 256 based on the compressor outlet temperature 264, the ambient temperature 212, and an efficiency of the CAC. For example, the charge cooler temperature module 260 may determine the charge cooler outlet temperature 256 for an engine system including a CAC using the equation: Charge Cooler Out Temp =Comp Out Temp−Charge Cooler Eff *(Com Out Temp−Amb Temp) where Charge Cooler Out Temp is the charge cooler outlet temperature 256, Comp Out Temp is the compressor outlet temperature 264, Amb Temp is the ambient temperature 212, and Charge Cooler Eff is the efficiency of the CAC. The charge cooler efficiency may initially be set to a predetermined maximum value (e.g., approximately 1.0), and the charge cooler temperature module 260 may selectively decrease the charge cooler efficiency over time as the CAC ages.

[0056] For engine systems where EGR is delivered upstream of the compressor 22, the charge cooler temperature module 260 may further determine the charge cooler outlet temperature 256 based on the EGR mass fraction 220 and the EGR cooler outlet temperature 216. For example, the charge cooler temperature module 260 may determine the charge cooler outlet temperature 256 for engine systems where EGR is delivered upstream of the compressor 22 using the equation: Charge Cooler Out Temp =Comp Out Temp−Charge Cooler Eff*[Com Out Temp −(1−EGR Mass Fraction)*Amb Temp+EGR Mass Fraction *EGR Cooler Out Temp)] where Charge Cooler Out Temp is the charge cooler outlet temperature 256, Comp Out Temp is the compressor outlet temperature 264, Amb Temp is the ambient temperature 212, Charge Cooler Eff is the efficiency of the CAC, EGR Mass Fraction is the EGR mass fraction 220 and EGR Cooler Out Temp is the EGR cooler outlet temperature 216.

[0057] A metal temperature module 268 determines a metal temperature 272 based on the intake gas temperature 208. The metal temperature 272 corresponds to a temperature of one or more metal components at the location where the recirculated exhaust gas is supplied to the intake system, i.e., the temperature of the metal EGR conduit at the location where the EGR system is connected to the intake system. The metal temperature module 268 further determines the metal temperature 272 based on a predetermined temperature offset. For example, the metal temperature module 268 may set the metal temperature 272 equal to or based on the intake gas temperature 208 plus the predetermined temperature offset. The predetermined temperature offset may be calibratable and may, for example, be set to approximately 30 degrees Celsius or another suitable temperature.

[0058] A reduction control module 276 selectively generates the first temperature reduction command 156 based on the inlet gas temperature 208 and / or the metal temperature 272. For example only, the reduction control module 276 may set the first temperature reduction command 156 to a first state when the inlet gas temperature 208 and / or the metal temperature 272 are greater than a first predetermined temperature. The reduction control module 276 may require the inlet gas temperature 208 and / or the metal temperature 272 to be greater than the first predetermined temperature for a first predetermined period of time before setting the first temperature reduction command 156 to the first state.

[0059] The first predetermined temperature may be calibratable and may be set to a temperature above which the intake manifold 14 may melt and / or lose its structural integrity. For example only, the first predetermined temperature may be approximately 150 degrees Celsius or another suitable temperature.

[0060] One or more remedial actions are selectively taken to reduce the one or more temperatures of the intake manifold 14. Now on Fig. 2 and Fig. 3, for example, the EGR control module 144 decreases the target EGR opening 148 when the first temperature decrease command 156 is in the first state. The EGR control module 144 may decrease the target EGR opening 148 to a predetermined opening when the first temperature decrease command 156 is in the first state. The predetermined opening may be a zero percent opening (to prevent EGR flow) or it may be a greater than zero percent opening (to allow a predetermined minimum amount of EGR flow).

[0061] The reduction control module 276 may transition the first temperature reduction command 156 from the first state to a second state when the inlet gas temperature 208 and the metal temperature 272 are less than a second predetermined temperature. The reduction control module 276 may require the inlet gas temperature 208 and the metal temperature 272 to be less than the second predetermined temperature for a second predetermined period of time before transitioning the first temperature reduction command 156 to the second state.

[0062] The second predetermined temperature is less than the first predetermined temperature. For example only, the second predetermined temperature may be approximately 140 degrees Celsius or another suitable temperature. The EGR control module 144 may increase the target EGR opening 148 when the first temperature decrease command 156 is in the second state.

[0063] One or more other remedial actions may be taken to reduce the intake gas temperature 208 and the metal temperature 272 when the intake gas temperature 208 and / or the metal temperature 272 are greater than a third predetermined temperature. The third predetermined temperature is less than the second predetermined temperature. For example only, the third predetermined temperature may be approximately 130 degrees Celsius or another suitable temperature. In this way, one or more other remedial actions may be taken to reduce the intake gas temperature 208 and the metal temperature 272 before reducing the EGR flow.

[0064] For example, a coolant control module 160 may turn on an electric coolant pump (not shown) and / or increase its speed when the inlet gas temperature 208 and / or the metal temperature 272 are greater than the third predetermined temperature. Turning on a coolant pump and / or increasing its speed may improve cooling and therefore decrease the inlet gas temperature 208 and the metal temperature 272.

[0065] Additionally or alternatively, the coolant control module 160 may open an electric thermostat valve (not shown) when the intake gas temperature 208 and / or the metal temperature 272 are greater than the third predetermined temperature. Opening a thermostat valve may improve cooling of the intake manifold 14, thereby reducing the intake gas temperature 208 and the metal temperature 272.

[0066] Additionally or alternatively, a flap control module 164 may open aerodynamic flaps (not shown) of the vehicle when the intake gas temperature 208 and / or the metal temperature 272 are greater than the third predetermined temperature. When open, the aerodynamic flaps admit air into an engine compartment. Opening the aerodynamic flaps may therefore improve cooling of the intake manifold 14 as well as reduce the intake gas temperature 208 and the metal temperature 272.

[0067] The reduction control module 276 may generate a second temperature reduction command 280 when the intake gas temperature 208 and / or the metal temperature 272 are greater than the third predetermined temperature. The coolant control module 160 may turn on the electric coolant pump, increase the speed of the electric coolant pump, and / or open the electric thermostat valve when the second temperature reduction command 280 is generated. Additionally or alternatively, the flap control module 164 may open the aerodynamic flaps when the second temperature reduction command 280 is generated.

[0068] Now on Fig. 4, a flowchart illustrating an example method for controlling the inlet gas temperature 208 and the metal temperature 272 is presented. Control may begin at 304, where the gas temperature module 204 determines the inlet gas temperature 208. At 308, the metal temperature module 268 determines the metal temperature 272. The determination of the inlet gas temperature 208 and the metal temperature 272 is described above.

[0069] At 312, the reduction control module 276 determines whether the intake gas temperature 208 and / or the metal temperature 272 are greater than the third predetermined value. If 312 is true, the reduction control module 276 generates the second temperature reduction command 280, and control continues at 316. At 316, the coolant control module 160 may turn on the electric coolant pump, increase the speed of the electric coolant pump, and / or open the electric thermostat valve. Additionally or alternatively, the flap control module 164 may open the aerodynamic flaps at 316. If 312 is false, control may end. The third predetermined temperature is less than the first and second predetermined temperatures, and may be, for example, approximately 130 degrees Celsius or another suitable temperature.

[0070] Control continues to 320 after 316. At 320, the reduction control module 276 determines whether the inlet gas temperature 208 and / or the metal temperature 272 are greater than the first predetermined temperature. If 320 is true, the reduction control module 276 sets the first temperature reduction command 156 to the first state, and control continues to 324. If 320 is false, control may end. The first predetermined temperature is greater than the second predetermined temperature and may be approximately 150 degrees Celsius or another suitable temperature. The reduction control module 276 may require the inlet gas temperature 208 and / or the metal temperature 272 to be greater than the first predetermined temperature for a first predetermined period of time before setting the first temperature reduction command 156 to the first state.

[0071] The EGR control module 144 decreases the target EGR opening 148 to the predetermined opening at 324 when the first temperature decrease command 156 is in the first state. The predetermined opening may be a zero percent opening (to prevent EGR flow) or it may be a greater than zero percent opening (to allow a predetermined minimum amount of EGR flow). Although control is shown and discussed as ending, the example of Fig. 4 may be a representation of a control loop, and control loops may be executed at a predetermined rate.

[0072] Now on Fig. 5, a flowchart illustrating an example method for disabling a reduction in EGR commanded to decrease intake gas temperature 208 and metal temperature 272 is presented. Control may begin at 404, where the gas temperature module 204 determines intake gas temperature 208. At 408, the metal temperature module 268 determines metal temperature 272. The determination of intake gas temperature 208 and metal temperature 272 is described above.

[0073] At 412, the reduction control module 276 determines whether the first temperature reduction command 156 is in the first state. If 412 is true, control continues to 416. If 412 is false, control may end. At 416, the reduction control module 276 determines whether the inlet gas temperature 208 and the metal temperature 272 are both less than the second predetermined temperature. If 416 is true, control continues to 420. If 416 is false, control may end. The reduction control module 276 may require the inlet gas temperature 208 and the metal temperature 272 to be less than the second predetermined temperature for a second predetermined period of time before transitioning the first temperature reduction command 156 to the second state.

[0074] The second predetermined temperature is less than the first predetermined temperature and greater than the third predetermined temperature. For example only, the second predetermined temperature may be approximately 140 degrees Celsius or another suitable temperature.

[0075] The reduction control module 276 transitions the first temperature reduction command 156 from the first state to the second state at 420 to deactivate the reduction in EGR flow commanded to reduce the intake gas temperature 208 and the metal temperature 272. The EGR control module 144 may then selectively increase the target EGR opening 148. Although control is shown and discussed as ending, the example of Fig. 5 may be a representation of a control loop, and control loops may be executed at a predetermined rate.

[0076] It is understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure.

[0077] In this application, including the definitions below, the term module may be replaced by the term circuit. The term module may refer to, be a part of, or include an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor (shared, dedicated, or grouped) that executes code; a memory (shared, dedicated, or grouped) that stores code executed by the processor; other suitable hardware components that provide the described functionality; or a combination of some or all of the foregoing, such as in a system on a chip.

[0078] The term code, as used above, may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, and / or objects. The term shared processor includes a single processor that executes some or all of the code of multiple modules. The term group processor includes a processor that, in combination with additional processors, executes some or all of the code of one or more modules. The term shared memory includes a single memory that stores some or all of the code of multiple modules. The term group memory includes memory that, in combination with additional memories, stores some or all of the code of one or more modules. The term memory may refer to a subset of the term computer-readable medium.The term "computer-readable medium" does not encompass transient electrical and electromagnetic signals propagating through a medium, and the medium can therefore be considered accessible and non-transitory. Non-limiting examples of non-transitory, accessible, computer-readable media include non-volatile memory, magnetic storage, and optical storage.

[0079] The devices and methods described in this application may be implemented partially or entirely by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions stored on a non-transitory, accessible, computer-readable medium. The computer programs may also include and / or rely on stored data.

Claims

[1] Engine control method for a vehicle, comprising: a temperature (208) of a gas in an intake manifold (14) of an engine (8) is determined; a temperature (272) of a metal exhaust gas recirculation (EGR) line is determined at a location where the EGR line is coupled to the intake manifold (14); and an opening of an EGR valve (30) is reduced when the temperature (208) of the gas or the temperature (272) of the line is greater than a predetermined temperature; and the opening of the EGR valve (30) is reduced until the temperature (208) of the gas and the temperature (272) of the conduit are less than a second predetermined temperature, which is less than the predetermined temperature, for a predetermined period of time. [2] The engine control method according to claim 1, wherein the predetermined temperature corresponds to a melting temperature of the intake manifold (14). [3] The engine control method of claim 1, further comprising reducing the opening of the EGR valve (30) to a predetermined opening when the temperature (208) of the gas and the temperature (272) of the conduit are greater than the predetermined temperature. [4] The engine control method of claim 1, further comprising fully closing the EGR valve (30) when the temperature (208) of the gas and the temperature (272) of the conduit are greater than the predetermined temperature. [5] The engine control method of claim 1, further comprising reducing the opening of the EGR valve (30) when the temperature (208) of the gas and the temperature (272) of the conduit are greater than the predetermined temperature for a predetermined period of time. [6] The engine control method of claim 1, further comprising, when the temperature (208) of the gas and / or the temperature (272) of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature: an electric coolant pump is switched on; and / or a speed of the electric coolant pump is increased. [7] The engine control method of claim 1, further comprising opening an electric thermostat valve when the temperature (208) of the gas and / or the temperature (272) of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature. [8] The engine control method of claim 1, further comprising opening aerodynamic flaps of the vehicle when the temperature (208) of the gas and / or the temperature (272) of the conduit is greater than a third predetermined temperature that is less than the predetermined temperature.

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