METHOD FOR THERMAL REGULATION FOR EFFICIENT LEAN WORKING MACHINES

Abstract

Methods for thermal control, including: Determine whether a catalytic converter (18) is active; Determine whether a catalyst (20) is active for selective catalytic reduction (SCR); Adjusting the air-fuel ratio of a machine (14) for operation at a stoichiometric ratio and retarding the ignition spark of the machine (14) when the catalytic converter (18) is not active; and Perform fuel injection when the catalytic converter (18) is active and the SCR catalyst (20) is not active; characterized by the fact that the catalytic converter (18) is a three-way catalyst (18); wherein, based on a first temperature of the catalytic converter (18) and a first active volume of the catalytic converter (18), it is determined whether the catalytic converter (18) is active; wherein, based on a second temperature of the SCR catalyst (20) and a second active volume of the SCR catalyst (20), it is determined whether the SCR catalyst (20) is active, wherein the second temperature is an average temperature determined as a weighted mean of temperatures T1 and T2 measured upstream and downstream of the SCR catalyst (20) according to the equation WA = x * T1 + (x-1) * T2, where WA is the weighted mean and x is a calibrated value between 0 and 1; and wherein the fuel injection is carried out by a post-fuel injection and / or by direct injection of fuel into an exhaust system (16) of the machine (14).

Description

AREA

[0001] The present disclosure relates to vehicle exhaust systems and in particular to a method according to the preamble of claim 1 for thermal control to maintain active temperatures of exhaust components, as is known, for example, from DE 10 2009 056 460 A1.

[0002] Furthermore, it is known from DE 10 2005 045 294 A1 to heat up an exhaust system by post-fuel injection or by direct injection of fuel into the exhaust system. It is also known from DE 10 2009 020 809 A1 to determine whether an EHC is active based on its active volume. BACKGROUND

[0003] During a combustion cycle of an internal combustion engine (ICE), air / fuel mixtures are supplied to the ICE cylinders. The air / fuel mixtures are compressed and burned to provide output torque. After combustion, pistons in the ICE force exhaust gases out of the cylinders through exhaust valve openings and into an exhaust system. The exhaust gases may contain nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HCs).

[0004] An ICE exhaust aftertreatment system can include a catalytic converter and a selective catalytic reduction (SCR) catalyst to reduce exhaust emissions. For example, a three-way catalyst converter (TWC) can be used to reduce NOx, CO, and HCs in the exhaust system. The TWC converts NOx into nitrogen and oxygen, CO into carbon dioxide, and oxidizes unburned HCs to produce carbon dioxide and water. An SCR catalyst can be located downstream of the TWC and can further reduce NOx in the exhaust system. An SCR catalyst converts NOx into nitrogen (N2) and water (H2O).

[0005] An average start-up temperature, at which a catalytic converter typically begins to function, is approximately 200–350°C. An average temperature above which an SCR catalyst is active is also approximately 200–350°C. Consequently, a catalytic converter and an SCR catalyst will not function, or will not provide a minimum emission reduction, if their temperatures are not maintained at or above their respective start-up and / or minimum active operating temperatures.

[0006] To increase and maintain temperatures of the catalytic converter and the SCR catalyst at or above the start-up and / or minimum active operating temperatures, lean operation of an ICE (Internal Combustion Engine) is limited. An ICE can be operated with a lean air / fuel ratio to minimize fuel consumption and improve its operating efficiency. The leaner the ICE is run, the less fuel is consumed and the more efficiently it operates.

[0007] However, the leaner the ICE is operated, the lower its operating temperatures, which reduces the amount of thermal energy transferred to exhaust system components. As the thermal energy to the exhaust system decreases, the temperatures of the catalytic converter and SCR catalyst can drop below their active operating temperatures. For this reason, lean operation is limited to maintain the operating temperatures of the catalytic converter and SCR catalyst above their active operating temperatures. Limiting lean operation limits the extent of the fuel consumption reduction.

[0008] The invention is based on the objective of providing a method with which the thermal control of exhaust gas treatment devices in an exhaust gas system can be carried out particularly reliably. SUMMARY

[0009] This problem is solved by a method having the features of claim 1.

[0010] Further applications of the present invention will become apparent from the following detailed description. It should be understood that the detailed description and specific examples are for illustrative purposes only. DRAWINGS

[0011] The present revelation is better understood through the detailed description and accompanying drawings, in which: Fig. 1 is a functional block diagram of a machine system that includes a thermal regulation system according to the present disclosure; Fig. 2 a functional block diagram of the system for thermal regulation of Fig. 1 is; Fig. 3 is a functional block diagram of a machine control module that includes a thermal control module according to the present disclosure; and Fig. 4 is a logical flowchart of a method for thermal control according to the present disclosure. DETAILED DESCRIPTION

[0012] The following description is merely exemplary. For clarity, the same reference symbols are used in the drawings to identify similar elements. The phrase "at least one of A, B, and C" used here is to be interpreted as meaning a logical (A or B or C) using a non-exclusive logical OR. It should be understood that steps within a process may be carried out in different orders without altering the principles of this disclosure.

[0013] The term "module" as used here can be or include an application-specific integrated circuit (ASIC); an electronic circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; other suitable components that provide the described functionality; or a combination of some or all of the above, as in a system-on-a-chip. The term "module" can also include memory (shared, dedicated, or group) that stores code executed by the processor.

[0014] The term "code," as used above, can include software, firmware, and / or microcode, and can refer to programs, routines, functions, classes, and / or objects. The term "shared," as used above, means that some or all of the code from multiple modules can be executed using a single (shared) processor. Additionally, some or all of the code from multiple modules can be stored in a single (shared) memory. The term "group," as used above, means that some or all of the code from a single module can be executed using a group of processors. Additionally, some or all of the code from a single module can be stored using a group of memory.

[0015] The devices and methods described herein may be implemented by one or more computer programs executed by one or more processors. The computer programs comprise processor-executable instructions stored on a non-volatile, concrete, computer-readable medium. The computer programs may also include stored data. Non-limiting examples of non-volatile, concrete, computer-readable media include non-volatile memory, magnetic storage, and optical storage.

[0016] The terminology used here serves only to describe certain exemplary embodiments and is not intended to be restrictive. As used here, singular forms "a," "an," and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprise," "comprehensive," "including," and "with" are inclusive and therefore establish the presence of specified features, tasks, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, tasks, operations, elements, components, and / or groups thereof.The procedural steps, processes, and operational procedures described here are not to be interpreted as requiring their execution in the specific order discussed or illustrated, unless that order is explicitly defined. It should also be understood that additional or alternative steps may be used.

[0017] Although the terms first, second, third, etc., may be used here to describe different elements, components, and / or devices, these elements, components, and / or devices are not intended to be limited by these terms. These terms may only be used to distinguish one element, component, or device from another. The terms, such as "first," "second," and other numerical terms, when used here, do not imply any sequence or order unless clearly indicated by the context. Thus, a first element, first component, or first device may, as discussed below, be referred to as a second element, second component, or second device without departing from the teachings of the exemplary embodiments.

[0018] In the Fig. 1 and Fig. Figure 2 shows a machine system 10 and a thermal control system 12. The machine system 10 is a low-emission vehicle system comprising a thermal control system 12 and a machine 14 with an exhaust system 16. The exhaust system 16 includes a catalytic converter 18 (CC) and a selective catalytic reduction (SCR) catalyst 20. The thermal control system 12 maintains the temperatures of the CC 18 and the SCR catalyst 20 above their respective start-up and / or minimum active operating temperatures.

[0019] The temperatures of CC 18 and SCR catalyst 20 are maintained while operation of the engine 14 with lean pre-combustion air and fuel (air / fuel) ratios is permitted. A lean air / fuel ratio may be one greater than a stoichiometric air / fuel ratio (e.g., 14.7:1). Temperatures of the engine 14 and / or the exhaust system 16 sections (excluding CC 18 and SCR catalyst 20) may decrease to temperatures below the start-up and / or minimum active operating temperatures when the engine 14 operates with lean air / fuel ratios. Lean engine operation and reduced engine operating temperatures reduce heat losses and improve fuel economy.

[0020] Machine system 10 includes machine 14, which burns an air / fuel mixture to generate drive torque. Although machine system 10 is shown as a spark-ignition direct injection engine, it is provided as an example. The thermal control system 12 can be implemented in various other machine systems, such as stratified charge engine systems, port fuel injection systems, homogeneous compression ignition (HCCI) engine systems, etc. Stratified charge engine systems can include direct injection engine systems in which fuel is ignited upon entering the cylinders of an engine.

[0021] During operation, air enters the engine 14 by passing through an air filter 21 and can be drawn into a turbocharger 22. The turbocharger 22, if present, compresses the fresh air. The greater the compression, the larger the output of the engine 14. The compressed air passes through an air cooler 24, if present, before entering an intake manifold 26. Air in the intake manifold 26 is distributed to cylinders 28. Fuel can be injected directly into the cylinders 28 by fuel injection devices 30. Spark plugs 32 ignite air / fuel mixtures in the cylinders 28. The combustion of the air / fuel mixtures produces exhaust gas. The exhaust gas leaves the cylinders 28 into the exhaust system 16.

[0022] The thermal control system 12 comprises the exhaust system 16 and an engine control module (ECM) 40. The exhaust system 16 includes the CC 18, the SCR catalyst 20, the ECM 40, and an exhaust manifold 42. In the example shown, the exhaust system 16 has, in the following order: the exhaust manifold 42, a first exhaust pipe 124, a second exhaust pipe 126, the CC FWC 18, a third exhaust pipe 128, the underbody FWC 20, and a fourth exhaust pipe 131. The air pump is connected to the exhaust manifold. The oxygen sensor is connected to the exhaust manifold upstream of the air pump.

[0023] The CC 18 features a three-way catalytic converter (TWC). The CC 18 can reduce nitrogen oxides (NOx), oxidize carbon monoxide (CO), and oxidize unburned hydrocarbons (HC) and volatile organic compounds (VOCs). The CC 18 oxidizes the exhaust gas based on an afterburning air / fuel ratio in the exhaust system 16. The amount of oxidation increases the exhaust gas temperature. The selective catalytic reduction (SCR) catalyst 20 can be used to further reduce NOx. The SCR catalyst 20 converts NOx into nitrogen (N2) and water (H2O).

[0024] Optionally, an EGR valve (not shown) recirculates a portion of the exhaust gas back into the intake manifold 26. The remainder of the exhaust gas is directed to the turbocharger 22 to drive a turbine. The turbine assists in compressing the fresh air drawn in by the air filter 21. Exhaust gas flows from the turbocharger 22 to the CC 18.

[0025] The System 12 thermal control can operate in various modes, including a CC heating mode, an SCR heating mode, and a lean-burn mode (or temperature maintenance mode). These modes can be triggered and controlled via the ECM 40 and / or a Thermal Control Module 60, which may be integrated as part of the ECM 40. The Thermal Control Module 60 is part of the System 12 thermal control and is described below in relation to the Fig. 3 and Fig. 4 further described.

[0026] During CC heating mode, CC 18 is heated to at least a CC start-up temperature (e.g., 200–350°C). In one implementation, CC 18 is heated to at least 250°C. The ECM 40 and / or the thermal control module 60 can adjust the pre-combustion air / fuel ratio of engine 14 to a stoichiometric ratio, while the ignition spark is retarded to heat CC 18. This allows heat transfer from engine 14 to the exhaust system 16 and heating of CC 18. Ignition timing control can, for example, retard from an ignition timing associated with top dead center (TDC) and / or a currently set ignition timing to retard the ignition spark. The currently set ignition timing can be before or after TDC.

[0027] During SCR heating mode, the SCR catalyst 20 is heated to at least an active temperature (e.g., 200–350°C). In one implementation, the SCR catalyst 20 is heated to at least 225°C. The ECM 40 and / or the thermal control module 60 can perform post-fuel injection and / or inject fuel into the exhaust system 16 to heat the SCR catalyst 20. Post-fuel injection can involve injecting fuel into the cylinders 28 after ignition of the air / fuel mixture in the cylinders 28 and before the intake strokes of the cylinders 28. This allows fuel to pass into the exhaust system 16. A hydrocarbon (HC) injection device 46 (in Fig. (2 shown) can be used to inject fuel directly into the exhaust system 16. A thermal control module 60 can signal a fuel pump 64 to supply fuel to the HC injection device 46. The HC injection device 46 can inject fuel into the exhaust system 16, for example, between the engine 14 and the CC 18, as shown.

[0028] The fuel supplied to the exhaust system 16 via post-fuel injection and / or via the HC injection unit 46 can, for example, be ignited in the CC 18. Thermal energy generated by the ignition of the fuel heats the SCR catalyst 20. The post-fuel injection and / or injection via the HC injection unit 46 can be controlled by a post-injection control module 68 of the module 60 for thermal control. The SCR heating mode does not need to be executed while the CC heating mode is executed.

[0029] During lean-burn mode, the ECM 40 and / or the thermal control module 60 operate the engine 14 with lean pre-combustion air / fuel ratios. The CC heating mode and the SCR heating mode do not need to be executed while the lean-burn mode is running.

[0030] The ECM 40 and / or the thermal control module 60 can control the machine system 10 and the thermal regulation system 12 based on sensor information. Sensor information can be obtained directly from sensors and / or indirectly via algorithms, models, and / or tables stored in the memory 70. Some example sensors 80 for determining exhaust flow levels, exhaust temperature levels, exhaust pressure levels, catalyst temperatures, oxygen levels, intake air flow rates, intake air pressure, intake air temperature, vehicle speed, engine speed, EGR, etc., are shown.The exhaust gas flow sensors 82, the exhaust gas temperature sensors 83, the exhaust gas pressure sensors 85, the catalyst temperature sensors 86, an ambient temperature sensor 87, an oxygen sensor 88, an EGR sensor 90, an intake air flow sensor 92, an intake air pressure sensor 94, an intake air temperature sensor 96, a vehicle speed sensor 98 and an engine speed sensor 99 are shown.

[0031] A first exhaust gas flow, pressure, and / or temperature sensor 100 can be connected to the second exhaust line 126 upstream of the CC 18. A second exhaust gas flow, pressure, and / or temperature sensor 102 can be connected to the third exhaust line 128 downstream of the CC 18. A first catalyst temperature sensor 104 can be connected to the CC 18. A third exhaust gas flow, pressure, and / or temperature sensor 106 can be connected to the fourth exhaust line 131 downstream of the SCR catalyst 20. A second catalyst temperature sensor 110 can be connected to the SCR catalyst 20. The ECM 40 and the module 60 for thermal control can control the operation of the catalyst heating system 12 and the machine 14 based on information from the sensors 80, 100, 102, 104, 106 and 110.

[0032] The thermal control module 60 can include a urea injection control module 120, which controls the injection of a reducing agent upstream of the SCR catalyst 20. For example, the reducing agent can be anhydrous ammonia, aqueous ammonia, or urea. The exhaust system 16 can include a urea supply system 130, which provides the reducing agent to a urea injection device 132. The urea injection device 132 can inject urea directly into the exhaust system 16, for example, between the CC 18 and a mixer 134 and / or between the CC 18 and the SCR catalyst 20. The mixer 134 is located in the second exhaust line 103.

[0033] Now also with reference to Fig. Figure 3 shows the ECM 40, which includes the thermal control module 60. The thermal control module 60 comprises a CC temperature monitoring module 150, a CC comparison module 152, and a CC temperature control module 154. The CC temperature monitoring module 150 can measure an operating and / or average temperature (CC temperature) T. CC (156) and an active volume CC AV (158) of CC 18 determine the active volume CC AV This concerns the volume of the CC 18 that is active (i.e., has a temperature higher than the start-up temperature). The CC temperature T CC and an active volume CC AV can be determined, for example, based on temperature signals T1 - T3 (160 - 164) from sensors 100, 102, 104, a machine model, an algorithm, etc.

[0034] As an example, the CC temperature monitoring module 150 can measure the CC temperature T CC and the active volume CC AVestimate the CC temperature T using a first thermal model and based on machine parameters and / or exhaust gas temperatures, some of which are described below with respect to equations 1 and 2. The CC temperature monitoring module can measure the CC temperature T CC Determine directly via sensors 100, 102, and 104. The first thermal model may include equations such as equations 1 and 2. TCC=f{ECCRate,SENG,CCMass,CCIMP,TEXH,DC,ERuntime,ELast,TAMB,CAM,SPK} CCAV=f{TCC,ECCRate,SENG,CCMass,CCIMP,TEXH,DC,ERuntime,ELast,TAMB,CAM,SPK}

[0035] F CCRate The exhaust gas flow through the CC 18 is a function of the mass airflow and the amount of fuel supplied to the cylinders. The mass airflow can be determined by an air mass flow sensor, such as the intake airflow sensor 92. ENGDC is the rotational speed of machine 14 (i.e., the rotational speed of a crankshaft of machine 14). CC is a duty cycle of machine 14. Mass is the mass of the CC 18. CC IMP is the resistance or impedance of the CC 18. E Laufzeit is the time that machine 14 is activated (ON). E Last The current load on the machine is 14. T EXH can relate to the temperature of the exhaust system 16 and be based on one or more of the sensors 100, 102, 104. T amb is the ambient temperature. CAM is the cam phase setting of machine 14. SPK is an ignition timing. The CC temperature T CC and the active volume CC AV can be based on one or more of the machine system parameters provided for in equations 1 and 2, and / or other machine system parameters.

[0036] The CC comparison module 152 compares the CC temperature T CCwith a catalyst start-up temperature T LO (166) and the active volume CC AV with a first catalyst threshold CC THR (168). The catalyst start-up temperature T LO and the first catalyst threshold CC THR can be predetermined and stored in memory 70. The CC comparison module 152 generates a first comparison signal C1 (170), which indicates whether the CC temperature T CC greater than the catalyst start-up temperature T LO is and whether the active volume CC AV greater than the first catalyst threshold CC THR is.

[0037] The CC temperature control module 154 determines, based on the first comparison signal C1, whether to operate in CC heating mode. The CC temperature control module 154 can operate in CC heating mode when the CC temperature T CC smaller than the catalyst start-up temperature T LO is and if the active volume CC AVsmaller than the first catalyst threshold CC THR The CC temperature control module 154 can generate and / or set a stoichiometric signal STÖCH (171) and / or retard a spark signal RET (172) to request that the engine 14 operate with stoichiometric air / fuel ratios and that the ignition timing of the engine 14 be retarded.

[0038] The stoichiometric signal STÖCH can be supplied to an air / fuel ratio control module 174. The air / fuel ratio control module 174 comprises an air control module 176 and a fuel control module 178. The air control module 176 generates an air control signal THR (180) based on the stoichiometric signal STÖCH. The air control signal THR can, for example, be supplied to a throttle actuator module 182 to control the position of a throttle plate and adjust the amount of air supplied to the cylinders 28. The fuel control module 178 generates a fuel control signal FUEL (184) based on the stoichiometric signal STÖCH. The fuel control signal FUEL can be supplied to a fuel actuator module 185 to adjust the amount of fuel supplied to the cylinders 28. The fuel actuator module 185 can control the operation of the fuel injection devices 30.

[0039] Any system that varies a machine parameter can be referred to as an actuator that receives an actuator value. For example, the throttle actuator module 182 can be referred to as an actuator, and the throttle opening area can be referred to as the actuator value. The throttle actuator module 182 can achieve a throttle opening area by adjusting the angle of a throttle valve vane. The throttle actuator module 182 can monitor the position of the throttle valve using one or more throttle position sensors (not shown). The air control module 176 can output a target area signal to the throttle actuator module 182 based on the stoichiometric signal STÖCH. The throttle actuator module 182 then regulates the throttle valve to produce the target throttle area.

[0040] The retarded ignition signal RET can be supplied to an ignition control module 186, which can generate an ignition control (or timing) signal SPARK (187) based on the retarded ignition signal RET. The ignition control signal SPARK can be supplied to an ignition spark actuator module 188. The ignition spark actuator module 188 can be referred to as an actuator, while a corresponding actuator value can be the magnitude of the ignition spark retard relative to cylinder TDC and / or a current ignition timing of a cylinder. The ignition spark actuator module controls the operation of the spark plugs 32.

[0041] Module 60 for thermal control further comprises an SCR temperature monitoring module 190, an SCR comparison module 191, and an SCR temperature control module 192. The SCR temperature monitoring module 190 can measure an operating and / or average temperature (SCR temperature) T. SCR (193) and an active volume SCR AV(194) of the SCR catalyst 20. The active volume SCR AV This concerns the volume of the SCR catalyst 20 that is active (i.e., has a temperature higher than the start-up temperature). The SCR temperature T SCR and an active volume SCR AV can be determined, for example, based on temperature signals T3 - T5 (164, 195, 196) from sensors 102, 106, 110, a machine model, an algorithm, etc.

[0042] As an example, the SCR temperature monitoring module 190 can monitor the SCR temperature T SCR and the active volume SCR AV estimate the SCR temperature T using a second thermal model and based on machine parameters and / or exhaust gas temperatures, some of which are described below with reference to equations 3 and 4. The SCR temperature monitoring module 190 can measure the SCR temperature T SCRDetermine directly via sensors 102, 106, and 110. The second thermal model may contain equations such as equations 3 and 4. TSCR=f{FSCRRate,SENG,SCRMass,SCRIMP,TEXH,DC,ERuntime,ELast,TAMB,CAM,SPK} CCAV=f{TSCR,ESCRRate,SENG,SCRMass,SCRIMP,TEXH,DC,ERuntime,ELast,TAMB,CAM,SPK}

[0043] F SCRRate The exhaust gas flow through the SCR catalyst 20 can be a function of the air mass flow and the amount of fuel supplied to the cylinders 28. SCR Mass The mass of the SCR catalyst is 20. SCR IMP is the resistance or impedance of the SCR catalyst 20. T EXH This can relate to the temperature of the exhaust system 16 and be based on one or more of the sensors 102, 106, 110. The SCR temperature T SCR and the active volume SCR AVcan be based on one or more of the machine system parameters provided for in equations 3 and 4, and / or other machine system parameters.

[0044] The SCR comparison module 191 compares the SCR temperature T SCR with an active temperature T ACT (197) and the active volume SCR AV (198) with a second catalyst threshold (SCR) THR The active temperature T ACT and the active volume SCR AV can be predetermined and stored in memory 70. The SCR comparator module 191 generates a second comparator signal C2 (199), which indicates whether the SCR temperature T SCR greater than the active temperature T ACT is and whether the active volume SCR AV greater than the second catalyst threshold SCR THR is.

[0045] The SCR temperature control module 192 can be part of the post-injection control module 68 and determines, based on the second comparison signal 2, whether to operate in SCR heating mode. The SCR temperature control module 192 can operate in SCR heating mode when the SCR temperature T SCR smaller than the active temperature T ACT is and if the active volume SCR AV smaller than the second catalyst threshold SCR THR The SCR temperature control module 192 can generate and / or set a post-injection signal POST (200) to request that the machine 14 perform post-injection and / or that the HC injection device 46 inject fuel directly into the exhaust system 16.

[0046] The post-injection signal POST can be supplied to the air / fuel ratio control module 174 and / or the fuel control module 178. The fuel control module 178 generates the fuel control signal FUEL based on the post-injection signal POST. The fuel control signal FUEL and / or an HC injection signal HCINJ (201) can be supplied to the fuel actuator module to adjust the amount of fuel supplied to the exhaust system 16.

[0047] The amount of fuel supplied to the exhaust system 16 during post-fuel injection and / or by the HC injection device 46 can be based on and / or as a function of the CC temperature T CC , the SCR temperature T SCR and the active volume CC AV , SCR AV This will be limited. This is achieved by regulating the amount of fuel injected into the exhaust system 16.

[0048] Another example is the SCR temperature T SCR The CC temperature monitoring module 150 determines a temperature gradient across the SCR catalyst 20 based on the temperature signals T1 and T2 from the temperature sensors 102 and 106. For example, the CC temperature monitoring module 150 can determine a difference between the first temperature signal T1 and the second temperature signal T2, as provided by equation 5. DEGREE = T1 − T2

[0049] A weighted mean value WA can be generated as a function of the temperature signals T1 and T2. Alternatively, the weighted mean value WA can be a weighted average of the temperature signals T1 and T2. An example of the weighted mean value WA is provided by Equation 6, where x is a calibrated value between 0 and 1. The calibrated value x can be calibrated, for example, based on thermocouple data from tested and / or modeled catalysts. WA=[(x)T1+(1−x)T2]

[0050] The weighted mean value WA indicates the average temperature of the SCR catalyst 20. The active volume SCR AV The active volume of the SCR catalyst 20 can be determined based on the temperature signals T1, T2, the weighted mean value WA, and / or other parameters. AVThe SCR catalyst 20 can be determined, for example, on the basis of the mass, resistance and / or impedance of the SCR catalyst 20, ambient temperature, engine speed, camshaft phase setting, ignition timing, duty cycle of the engine, etc., as described above.

[0051] A temperature gradient across the CC 18 can also be determined to calculate the CC temperature T. CC to determine using sensors 100 and 102. The active volume CC AV The CC 18 can be determined based on the temperature signals of sensors 100, 102, the value of the weighted mean determined therefrom, and / or other parameters (some of which are noted above).

[0052] System 12 for thermal regulation can be operated using numerous methods, one exemplary method being the method of Fig. 4 is provided. In Fig. Figure 4 shows a method for thermal control. Although the following tasks mainly relate to the implementations of the Fig. As described in sections 1-3, the tasks can be easily modified to apply to other implementations of the present disclosure. The tasks can be performed iteratively. The procedure can begin at 202.

[0053] Sensor signals are generated at 203. For example, sensors 80, 100, 102, 104, 106, and 110 can each generate sensor signals.

[0054] In task 204, the thermal control module 60 determines whether the CC 18 and the SCR catalyst 20 are active. Task 206 is executed if both the CC 18 and the SCR catalyst 20 are active; otherwise, task 208 is executed. The CC temperature control module can determine whether the CC 18 is active based on the first comparison signal. The SCR temperature control module can determine whether the SCR catalyst 20 is active based on the second comparison signal.

[0055] At 206, the machine 14 is operated in lean operating mode.

[0056] At 208, the CC comparison module determines whether the CC temperature T CC smaller than the catalyst start-up temperature T LO (or within a first predetermined temperature range) and whether the active volume CC AV smaller than the first catalyst threshold CC THR Task 210 is executed when the CC temperature T CCsmaller than the catalyst start-up temperature T LO (or within the first predetermined temperature range) and when the active volume CC AV smaller than the first catalyst threshold CC THR If it is, otherwise task 212 will be executed.

[0057] At 210, the air / fuel ratio control module, the air control module, and / or the fuel control module generate the air control signal THR and the fuel control signal FUEL for operating the machine 14 at stoichiometric ratios. The ignition spark control module generates the ignition spark control signal SPARK to retard the ignition timing of the machine 14 from TDC and / or from a current ignition timing. Task 203 is performed after Task 210.

[0058] A retarded ignition timing of machine 14 can involve a delay of the ignition timing by a predetermined amount (or number of degrees) from a predetermined or present ignition point (or a predetermined number of degrees from TDC). The predetermined or present ignition point can be an advanced point (a point before TDC), a point equal to TDC, or a point after TDC. A retarded ignition point can be defined as a change in the ignition timing such that fuel ignition occurs later in the combustion cycle.

[0059] Task 212 can be executed when CC 18 is active. In task 212, the SCR comparison module determines whether the SCR temperature T SCR smaller than the active temperature T ACT (or within a second predetermined temperature range) and whether the active volume SCR AVsmaller than the second catalyst threshold SCR THR Task 214 is executed when the SCR temperature T SCR smaller than the active temperature T ACT (or within the second predetermined temperature range) and when the active volume SCR AV smaller than the second catalyst threshold SCR THR If it is, otherwise task 203 will be executed.

[0060] In 214, the air / fuel ratio control module and / or the fuel control module performs a post-injection and / or direct injection of fuel into the exhaust system 16 via the HC injection device 46. The amount of fuel supplied to the exhaust system 16 can be increased and limited to a predetermined level, as described above. This is done to increase the temperature of the SCR catalyst 20. Task 203 can be performed after task 214.

[0061] The tasks described above are meant as illustrative examples; the tasks can be executed sequentially, synchronously, simultaneously, continuously, during overlapping time periods, or in various orders depending on the application. In one implementation, task 204 is not executed, and task 208 is executed after task 202.

[0062] The implementations described above maximize fuel-efficient operation by providing targeted catalyst heating while allowing the engine to operate at increased lean air / fuel ratios. Temperatures of a catalytic converter and / or SCR catalyst are maintained, while temperatures of the engine and / or upstream sections of an exhaust system are allowed to decrease. The increased lean air / fuel ratios and reduced operating temperatures decrease fuel consumption and heat losses associated with engine operation.

Claims

[1] Methods for thermal control, comprising: Determine whether a catalytic converter (18) is active; Determine whether a catalyst (20) is active for selective catalytic reduction (SCR); Adjusting the air-fuel ratio of a machine (14) for operation at a stoichiometric ratio and retarding the ignition spark of the machine (14) when the catalytic converter (18) is not active; and Perform fuel injection when the catalytic converter (18) is active and the SCR catalyst (20) is not active; characterized by , that the catalytic converter (18) is a three-way catalyst (18); wherein, based on a first temperature of the catalytic converter (18) and a first active volume of the catalytic converter (18), it is determined whether the catalytic converter (18) is active; wherein, based on a second temperature of the SCR catalyst (20) and a second active volume of the SCR catalyst (20), it is determined whether the SCR catalyst (20) is active, wherein the second temperature is an average temperature determined as a weighted mean of temperatures T1 and T2 measured upstream and downstream of the SCR catalyst (20) according to the equation WA = x * T1 + (x-1) * T2, where WA is the weighted mean and x is a calibrated value between 0 and 1; and wherein the fuel injection is carried out by a post-fuel injection and / or by direct injection of fuel into an exhaust system (16) of the machine (14). [2] Method for thermal control according to claim 1, further comprising: Adjusting the air and fuel ratio of the machine (14) for operation at the stoichiometric ratio and retarding the ignition spark of the machine (14) based on (i) the first temperature and first active volume and (ii) the second temperature and second active volume. [3] Method for thermal control according to claim 1, further comprising: Generating an initial comparison signal based on a comparison between the initial temperature and a start-up temperature, and a comparison between the initial active volume and an initial threshold; Request for operation of the machine (14) at stoichiometry; and Request for late adjustment of the ignition spark of the machine (14) based on the first comparison signal. [4] Method for thermal control according to claim 3, further comprising: Determining the second temperature of the SCR catalyst (20) and the second active volume of the SCR catalyst (20); and Generating a second comparison signal based on a comparison between the second temperature and an active temperature and a comparison between the second active volume and a second threshold; and Generating a post-injection signal to supply fuel to the exhaust system based on the second comparison signal. [5] Method for thermal control according to claim 4, wherein: the machine (14) is operated at stoichiometric air and fuel ratios and the ignition spark of the machine (14) is retarded when the first temperature is lower than the starting temperature and the first active volume is lower than the first threshold; and Fuel is supplied to the exhaust system when the second temperature is lower than the active temperature and the second active volume is lower than the second threshold. [6] Method for thermal control according to claim 4, further comprising limiting a quantity of fuel supplied to the exhaust system (16) based on the first temperature and first active volume and the second temperature and second active volume. [7] Method for thermal control according to claim 1, further comprising limiting the amount of fuel supplied to the exhaust system (16) based on the temperature of the SCR catalyst (20) and the active volume. [8] Method for thermal control according to claim 1, further comprising operating the machine (14) with lean air and fuel ratios when the catalytic converter (18) and the SCR catalyst (20) are active.

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