Methods and systems for multivariable engine control

Abstract

In an exemplary embodiment, a method and system for multivariable torque control of a vehicle are provided. The method includes configuring a processor disposed in a multivariable controller to determine a set of references associated with exhaust gas recirculation (EGR); implementing an algorithm based on engine temperature and at least one reference associated with EGR to generate commands for controlling a set of actuators; optimizing at least one cam phase position, the optimization being controlled by applying an appropriate level of engine torque for vehicle propulsion based on the generated commands; limiting an allowable range of cam phases of a set of cams associated with the operation of the EGR valve based on humidity and the amount of EGR introduced by the EGR valve during the internal combustion phase of vehicle operation; and providing an amount of propulsion torque from the engine according to instructions provided by the processor.

Description

Technical Field

[0001] The technical field generally relates to internal combustion engines, and more specifically to a system and method for multivariable engine control, which uses cam phasers with combined humidity and EGR dilution values, while simultaneously implementing scheduled cam phaser references and constraints and reference EGR setpoints to optimize engine performance. Background Technology

[0002] Exhaust gas recirculation (EGR) valves recirculate a significant amount of exhaust gas back into the engine intake system to improve engine efficiency, reduce fuel consumption, and lower NOx emissions. Engine control systems have been developed to control engine output torque to achieve the desired torque. However, conventional engine control systems fail to control engine output torque as accurately as desired because they fail to consider or adequately account for other variables associated with external humidity and intake air dilution, which affect the intake mixture and can degrade engine performance. Furthermore, conventional engine control systems do not provide a rapid response to control signals or coordinate engine torque control among the various components affecting engine output torque.

[0003] Therefore, it is desirable to provide an improved method and system for a multivariable engine control system that has control over one or more cam phasers and EGR valves to introduce scheduling constraints in cam phaser operation and maintain acceptable combustion stability under different EGR and ambient humidity operating conditions.

[0004] Therefore, it is desirable to provide an improved method and system for a variable engine control system that controls a set of cam phasers, the set of cam phasers including a combined intake cam and exhaust cam with an external EGR, for enhancing the control of the internal combustion engine; and to simplify multiple effects caused by humidity and EGR into a single value for generating at least one command to limit the operation of one or more cam phases.

[0005] Furthermore, other desirable features and characteristics of this disclosure will become apparent from the following detailed description and appended claims, in conjunction with the accompanying drawings and the foregoing technical field and background. Summary of the Invention

[0006] In an exemplary embodiment, a method for multivariable torque control of a vehicle is provided.

[0007] The method includes configuring a processor located in a multivariable controller and programming the processor with a set of instructions to determine a set of references associated with exhaust gas recirculation (EGR); implementing an algorithm by the processor that, based on engine temperature and at least one reference determined from the set of references associated with EGR, generates one or more commands for controlling a set of actuators; optimizing at least one cam phase position by the processor, the optimization being controlled by applying an appropriate level of engine torque for vehicle propulsion based on the generated commands to at least one actuator in the actuator group; limiting the permissible range of cam phases of a set of cams associated with the operation of the EGR valve by the processor, based on humidity and the amount of EGR introduced by the EGR valve during the internal combustion phase of vehicle operation; and providing the amount of propulsion torque by the vehicle's engine according to instructions provided by the processor.

[0008] In at least one exemplary embodiment, the method further includes: using cam phasing by a processor, comprising an intake cam and an exhaust cam in combination with an external EGR, to enhance the control of the internal combustion engine; and the processor simplifying multiple effects caused by humidity and EGR into a single value to generate at least one command to limit the operation of one or more cam phasers.

[0009] In at least one exemplary embodiment, the method further includes having the processor combine the values ​​of humidity and EGR into a single dilution value as the basis for scheduling a set of cam phaser constraints.

[0010] In at least one exemplary embodiment, the method further includes having the processor tune the values ​​of the set of cam phaser constraints to optimize engine performance while preventing poor combustion stability.

[0011] In at least one exemplary embodiment, the method further includes a value used for EGR reference based on one or more values ​​contained in a set of calibration tables that include high-pressure and low-pressure values.

[0012] In at least one exemplary embodiment, the method further includes adjusting the EGR reference by a processor based on a set of values ​​associated with humidity, engine coolant, and air temperature.

[0013] In at least one exemplary embodiment, the method further includes a coefficient, tuned by a processor, for adjusting the value of the EGR reference based on a set of values ​​associated with humidity, engine coolant, and air temperature.

[0014] In at least one exemplary embodiment, the method further includes, wherein the dilution value further includes, the processor using the current dilution value as input, interpolating between a set of dilution values ​​including a low dilution value, a nominal dilution value, and a maximum dilution value, and a corresponding set of calibration tables, to determine a set of phaser constraints, the set of phaser constraints including an intake phaser maximum thrust constraint, an intake phaser maximum delay constraint, an exhaust phaser maximum thrust constraint, and an exhaust phaser maximum delay constraint.

[0015] In at least one exemplary embodiment, the method further includes reducing the amount of EGR by the processor in response to a high humidity level in order to maintain a constant value for the dilution value.

[0016] In at least one exemplary embodiment, the method includes: controlling the operation of an EGR valve by a processor calculating a percentage value of an EGR reference used as the basis for a target setpoint; determining percentage values ​​of the EGR reference at low and high atmospheric pressures by the processor based on values ​​contained in a set of calibration tables; determining an initial percentage value of the EGR reference by the processor applying a set of values ​​associated with the measured atmospheric pressure and using an interpolation function; and adjusting the percentage value of the EGR reference by the processor according to the current humidity by using a linear relationship function between the current humidity value and a percentage value associated with EGR reduction.

[0017] In at least one exemplary embodiment, the method includes using a set of cam phaser values ​​from first, second, and third sets of cam phaser calibration tables, the cam phaser calibration tables including a first calibration table containing cold cam phaser values, a second calibration table containing warm cam phaser values, and a third calibration table containing EGR phaser values; mixing during engine warm-up, the cold-warm calibrator mix containing values ​​between 0 and 1, wherein the values ​​of the cold-warm calibrator mix provide a basis for applying an interpolation function between the cold cam phaser values ​​and the warm cam phaser values; further mixing upon introduction of EGR, including calculating a value for an EGR mixing factor by dividing a final percentage of the EGR reference by a nominal percentage value of the EGR reference corresponding to the current humidity. The EGR mixing factor provides a basis for applying an interpolation function between the warm cam phaser values ​​and the EGR cam phaser values; and generating a set of values ​​as reference target values ​​corresponding to cam phaser commands for providing propulsion torque from the vehicle's engine according to instructions provided by a processor.

[0018] In another exemplary embodiment, a system for multivariable torque control of a vehicle is provided. The system includes an engine; and a processor disposed in a multivariable controller coupled to the engine and configured to: determine a set of references associated with exhaust gas recirculation (EGR); implement an algorithm based on engine temperature and at least one reference determined from the set of references associated with EGR to generate one or more commands for controlling a set of actuators; optimize at least one cam phase position, the optimization being controlled by applying an appropriate level of engine torque for vehicle propulsion based on the generated commands to at least one actuator in the actuator group; limit the permissible range of cam phases of a set of cams associated with the operation of an EGR valve based on humidity and the amount of EGR introduced by the EGR valve during the internal combustion phase of vehicle operation; and provide an amount of propulsion torque from the vehicle's engine according to instructions provided by the processor.

[0019] In at least one exemplary embodiment, the system further includes a processor configured to use cam phasing, comprising an intake cam and an exhaust cam in combination with an external EGR, for enhancing control of the internal combustion engine; and to simplify multiple effects caused by humidity and EGR into a single value for generating at least one command to limit the operation of one or more cam phasers.

[0020] In at least one exemplary embodiment, the system includes a processor further configured to combine the values ​​of humidity and EGR into a single value of dilution, which serves as the basis for scheduling a set of cam phaser constraints.

[0021] In at least one exemplary embodiment, the system includes: wherein the processor is further configured to tune the values ​​of the set of cam phaser constraints to optimize engine performance while preventing poor combustion stability, wherein the value used for the EGR reference is based on one or more values ​​contained in a set of calibration tables that include high-pressure and low-pressure values.

[0022] In at least one exemplary embodiment, the system includes a processor further configured to adjust an EGR reference based on a set of values ​​associated with humidity, engine coolant, and air temperature.

[0023] In at least one exemplary embodiment, the system includes a processor further configured to interpolate between a set of dilution values, including a low dilution value, a nominal dilution value, and a maximum dilution value, and a corresponding set of calibration tables, using a current dilution value as input, to determine a set of phaser constraints, including an intake phaser maximum propulsion constraint, an intake phaser maximum delay constraint, an exhaust phaser maximum propulsion constraint, and an exhaust phaser maximum delay constraint.

[0024] In at least one exemplary embodiment, the system includes a processor further configured to reduce the amount of EGR in response to a high humidity level in order to maintain a constant dilution value.

[0025] In at least one exemplary embodiment, the system includes a processor further configured to: control an EGR valve by performing a set of actions to: calculate a percentage value of an EGR reference based on a target setpoint; determine percentage values ​​of the EGR reference at low and high atmospheric pressures based on values ​​contained in a set of calibration tables; apply a set of values ​​associated with the measured atmospheric pressure and use an interpolation function to determine an initial percentage value of the EGR reference on the set of calibration tables; and adjust the percentage value of the EGR reference according to the current humidity by using a linear relationship function between the current humidity value and the percentage value associated with EGR reduction.

[0026] In at least one exemplary embodiment, the system includes a processor further configured to: use a set of cam phaser values ​​from first, second, and third sets of cam phaser calibration tables, the cam phaser calibration tables including a first calibration table containing cold cam phaser values, a second calibration table containing warm cam phaser values, and a third calibration table containing EGR phaser values; perform mixing during engine warm-up, the cold-warm calibrator mixing containing values ​​between 0 and 1, wherein the values ​​of the cold-warm calibrator mixing provide a basis for applying an interpolation function between the cold cam phaser values ​​and the warm cam phaser table values; further mix upon introduction of EGR, including calculating a value for an EGR mixing factor by dividing the final percentage of the EGR reference by a nominal percentage value of the EGR reference corresponding to the current humidity. The EGR mixing factor provides a basis for applying an interpolation function between the warm cam phaser values ​​and the EGR cam phaser values; and generate a set of values ​​as reference target values ​​corresponding to cam phaser commands for providing propulsion torque by the vehicle's engine. Attached Figure Description

[0027] The present disclosure will now be described in conjunction with the following figures, wherein the same numerals denote the same elements, and wherein:

[0028] Figure 1 Exemplary diagrams of a vehicle according to various embodiments are shown, the vehicle including a multivariable torque control system and other components of a propulsion system, and various actuators in response to commands from an intake cam and an exhaust cam controlled by a vehicle controller;

[0029] Figure 2An exemplary functional block diagram of a vehicle according to various embodiments is shown. The vehicle includes a multivariable torque control system for limiting cam phaser operation by analyzing the effects of humidity and EGR on combustion to maximize engine performance and stability, and for determining the optimal cam phase position by issuing various commands for cam phaser operation.

[0030] Figure 3 An exemplary graph is shown illustrating a set of comparisons between humidity and EGR introduced in control modes for low dilution, nominal dilution, and maximum dilution, according to various embodiments. This comparison combines humidity and dilution in a single dilution value that limits the cam phaser to maximize engine performance.

[0031] Figure 4 An exemplary diagram is shown of a set of calibration tables according to various exemplary embodiments, the set of calibration tables containing values ​​for defining three dilution setpoints for controlling one or more cam phaser constraints and EGR valves by a multivariable controller;

[0032] Figure 5 An exemplary diagram of multivariable engine control according to various exemplary embodiments is shown, which utilizes three sets of exemplary calibration tables with cam phaser reference values ​​to control one or more cam phasers and EGR values;

[0033] Figure 6 An exemplary diagram illustrating a process for calculating the percentage of an EGR reference value used as a target setpoint by a multivariable control system, according to various exemplary embodiments; and

[0034] Figure 7 This illustrates a set of references associated with EGR and EGR constraints according to various exemplary embodiments. Figure 1-6 An exemplary flowchart of multivariable torque control for a vehicle is described, wherein the steps simplify the effects of humidity and EGR on a single dilution value used to limit cam phaser operation. Detailed Implementation

[0035] The following detailed description is exemplary in nature and is not intended to limit this disclosure or its application and use. Furthermore, there is no intention to be bound by the preceding background or any theories set forth in the following detailed description.

[0036] The use of intake and / or exhaust camshaft phasing in internal combustion engines allows for greater control, which has the advantages of optimizing engine performance, improving fuel efficiency, and reducing emissions. However, under certain environmental conditions, it is necessary to limit the usable cam overlap based on the amount of ambient humidity to maintain good combustion stability. To achieve the optimal overlap, the humidity of the introduced air can be measured or estimated. This humidity, combined with the EGR dilution value, is then used to create a set of cam position constraints that can be tuned to optimize engine performance while preventing undesirable combustion stability.

[0037] Figure 1 A vehicle 100 according to an exemplary embodiment is shown. As described in further detail below, the vehicle 100 includes an engine control module (ECM) 114 configured for multivariable torque control to limit camshaft phaser operation by analyzing the effects of humidity and EGR on combustion, in order to maximize engine performance and stability of the vehicle 100 according to an exemplary embodiment.

[0038] In various embodiments, vehicle 100 includes an automobile. In some embodiments, vehicle 100 can be any of many different types of automobiles, such as sedans, vans, trucks, or sport utility vehicles (SUVs), and may be two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD) and / or various other types of vehicles. In some embodiments, vehicle 100 may also include motorcycles or other vehicles, such as aircraft, spacecraft, ships, etc., and / or one or more other types of mobility platforms (e.g., robots and / or other mobility platforms).

[0039] Vehicle 100 includes a body 104 disposed on a chassis 116. Body 104 substantially encloses the other components of vehicle 100. Body 104 and chassis 116 may together form a frame. Vehicle 100 also includes a plurality of wheels 112. Each wheel 112 is rotatably coupled to chassis 116 near a corresponding corner of body 104 to facilitate movement of vehicle 100. In one embodiment, vehicle 100 includes four wheels 112, although this may vary in other embodiments (e.g., for trucks and certain other vehicles).

[0040] The drive system 111 is mounted on the chassis 116 and drives the wheels 112, for example, via axle 117. In various embodiments, the drive system 111 includes an engine 102 that drives the wheels 112 via axle 117 and also provides propulsion torque for automatic braking of the vehicle 100. In some embodiments, the engine 102 includes an internal combustion engine. In various other embodiments, one or more other types of engines 102 may also be included, such as a hybrid engine / internal combustion engine, and / or one or more other different types of engines.

[0041] As also depicted in various embodiments, drive system 111 includes transmission 113. In various embodiments, transmission 113 can be automatically and / or manually shifted into different gears, such as drive (D), parking (P), reverse gear (R), etc.

[0042] In various embodiments, vehicle 100 also includes an internal combustion engine 102, which includes a piston 125. During the combustion stroke, combustion of the air / fuel mixture drives piston 125 away from top dead center (TDC), thereby driving crankshaft 119. Thus, crankshaft 119 is rotatable to provide driving torque to propel the motor vehicle, wherein piston-cylinder block assembly 99 is configured to combust the air / fuel mixture to rotate crankshaft 119. The combustion stroke can be defined as the time between the moment piston 125 reaches TDC and the moment piston 125 reaches bottom dead center (BDC).

[0043] During the exhaust stroke, piston 125 begins to move away from the BDC and discharges combustion products (exhaust gases) through exhaust valve 130. Therefore, exhaust valve 130 is configured to discharge exhaust gases from piston-cylinder assembly 99. Combustion products are discharged from the vehicle through exhaust system 134.

[0044] Intake valve 122 is controlled by intake camshaft 140, while exhaust valve 130 is controlled by exhaust camshaft 142. Therefore, intake camshaft 140 is configured to rotate to control intake valve 122, and exhaust camshaft 142 is configured to rotate to control exhaust valve 130. It should be understood that intake camshaft 140 or multiple intake camshafts 140 typically control multiple intake valves 122 associated with one or more cylinders 118 in one or more cylinder banks.

[0045] Similarly, the exhaust camshaft 142 or multiple exhaust camshafts 142 will typically control multiple exhaust valves 130 associated with one or more cylinders 118 in one or more cylinder banks. It should also be understood that the intake valve 122 and / or exhaust valve 130 may be controlled by a device other than the camshaft (e.g., a camless valve actuator).

[0046] The opening and closing times of intake valve 122 relative to piston TDC are varied by intake camshaft phaser 148. For example, intake camshaft phaser 148 can be configured to control the rotation of intake camshaft 140 by controlling the intake cam phase angle of intake camshaft 140. Correspondingly, the opening and closing times of exhaust valve 130 relative to piston 125 TDC are varied by exhaust camshaft phaser 150. Exhaust camshaft phaser 150 can be configured to control the rotation of exhaust camshaft 142 by controlling the exhaust cam phase angle of exhaust camshaft 142. Phaser actuator module 158 controls intake camshaft phaser 148 and exhaust camshaft phaser 150 based on signals from engine control module (ECM) 114. Optionally, variable valve lift can also be controlled by phaser actuator module 158.

[0047] The propulsion system of vehicle 100 (i.e., engine 102 and exhaust system 134) also includes an exhaust gas recirculation (EGR) valve 170, which is configured to selectively redirect a portion of exhaust gas back into intake manifold 110 through a selectively variable EGR valve opening region. EGR valve 170 is controlled by EGR actuator module 172 based on signals from ECM 114.

[0048] Engine 102 also includes a humidity sensor 107. The humidity sensor detects the water vapor concentration of air entering the intake manifold 110 via the intake passage. The humidity sensor 107 can be positioned downstream of the EGR valve 170 and upstream of the intake valve 122. Based on the position of the EGR valve 170, the relative humidity reading generated by the humidity sensor indicates the humidity of the fresh air or a combination of fresh air and recirculated exhaust gas.

[0049] The position of crankshaft 119 is measured using crankshaft position sensor 180. The rotational speed of crankshaft 119, which is also the rotational speed of engine 102, can be determined based on crankshaft position. The temperature of the engine coolant is measured by engine coolant temperature (ECT) sensor 182. ECT sensor 182 is preferably located within engine 102 or at another location in the coolant circulation loop, such as the cooler.

[0050] The pressure within the intake manifold 110 is measured using a manifold absolute pressure (MAP) sensor 184. Optionally, engine vacuum, which is the difference between ambient air pressure and the pressure within the intake manifold 110, can be measured. The mass flow rate of air flowing into the intake manifold 110 is measured using a mass flow rate (MAF) sensor 186.

[0051] exist Figure 1In this process, based on the air torque request 265, a command or target value for the engine actuators used to control airflow is determined. More specifically, based on the air torque request 265, the air control module 228 uses model predictive control to determine the commanded exhaust valve opening region 266, the commanded throttle opening region 267, the commanded EGR valve opening region 268, the commanded intake camshaft phase angle 269, and the commanded exhaust camshaft phase angle 270.

[0052] In various embodiments, the engine control module (ECM) 114 includes a controller (or computer system) 141 that controls vehicle operation based on processing performed by the controller 141 using sensor data and other data and / or information obtained through the ECM 114. The operation includes utilizing propulsion torque provided by the engine 102 according to instructions provided by the controller 141.

[0053] ECM114 receives input from atmospheric (i.e., air pressure) sensor 181 to determine the air pressure of the ambient air inside or around the vehicle, and uses this input in part to adjust the air / fuel ratio and ignition timing to change altitude conditions (and thus the density of the air entering engine 102).

[0054] In various embodiments, controller 141 (and in some embodiments, is located within the main body of vehicle 100. It should be understood that controller 141 may be otherwise different) Figure 1 The embodiments described herein. For example, controller 141 may be coupled to or otherwise utilize one or more remote computer systems and / or other control systems, for example as part of one or more of the above-described vehicle 100 devices and systems.

[0055] In the depicted embodiment, the computer system of controller 141 includes a computer system (also referred to herein as a computer system) and includes a processor 152, memory 144, storage device 168, and computer bus 150. Processor 152 performs the computational and control functions of controller 141 and may include any type of processor or multiple processors, a single integrated circuit (e.g., a microprocessor), or any suitable number of integrated circuit devices and / or circuit boards that coordinate to perform the functions of the processing unit. During operation, processor 152 executes one or more programs 153 contained in memory 144, and therefore typically performs operations related to... Figure 2-7 During the description, the general operation of the control controller 141 and the computer system of the controller 141 is explained.

[0056] Memory 144 can be any suitable type of memory. For example, memory 144 may include various types of dynamic random access memory (DRAM) (e.g., SDRAM), various types of static RAM (SRAM), and various types of non-volatile memory (PROM, EPROM, and flash memory). In some instances, memory 144 is located on and / or co-located on the same computer chip as processor 152.

[0057] Bus 150 is used to transmit programs, data, status and other information or signals between various components and interfaces (not shown) of the computer system of controller 141, thereby allowing communication between the computer system of controller 141, for example, from a system driver and / or another computer system, and can be implemented using any suitable method and device.

[0058] Storage device 168 can be any suitable type of storage device, including different types of direct access storage devices and / or other memory devices. In one exemplary embodiment, storage device 168 includes a program product from which memory 144 can receive a program 153 that executes one or more embodiments of one or more processes of this disclosure, such as regarding... Figure 2-7 As mentioned above.

[0059] Bus 150 can be any suitable physical or logical method for connecting computer systems and components. This includes, but is not limited to, direct hardwired connections, fiber optic, infrared, and wireless bus technologies. During operation, program 153 is stored in memory 144 and executed by processor 152.

[0060] It should be understood that although this exemplary embodiment is described in the context of a fully operational computer system, those skilled in the art will recognize that the mechanisms of this disclosure can be distributed as a program product having one or more types of non-transitory computer-readable signal-bearing media for storing a program and its instructions and for executing its distribution, such as a non-transitory computer-readable medium carrying a program and containing computer instructions stored therein for causing a computer processor (e.g., processor 152) to run and execute the program.

[0061] Such program products can take various forms, and this disclosure applies equally to any particular type of computer-readable signal-bearing medium used for execution of the distribution. Examples of signal-bearing media include recordable media such as floppy disks, hard disks, memory cards, and optical disks, and transmission media such as digital and analog communication links. It should be understood that, in some embodiments, cloud-based storage and / or other technologies may also be used with particular embodiments. It should also be understood that the computer system of controller 141 may also differ from other... Figure 1The embodiments depicted herein, for example, include a computer system of controller 141 that may be coupled to or otherwise utilize one or more remote computer systems and / or other control systems.

[0062] Figure 2 An exemplary diagram of a multivariable torque control system according to an exemplary embodiment is shown. The multivariable torque control system determines the optimal cam phase position by issuing various commands for cam phaser operation. Figure 2 The image shows a set of references for reference module 205, which includes a percentage EGR reference module 210 to generate a set of signals indicating a percentage value associated with the EGR reference, and a set of phaser reference modules to generate a set of signals associated with the values ​​of the phaser references.

[0063] In this embodiment, a set of references generated by reference module 205 is sent to the Y and U references of multivariable controller 230, which uses a processor to implement the algorithm, partially using the EGR percentage reference (i.e., EGRY). ref The Y and U references are combined with the Y and U constraints generated by the constraint module 220 to issue a set of U commands 240. The U commands 240 include (although not implemented) commands for actions associated with the throttle, exhaust valve, camshaft phaser, EGR valve, and spark plug components.

[0064] In this embodiment, reference module 205 calculates a percentage value for an EGR reference via percentage EGR module 210, where the percentage EGR reference value is calculated and used as a target setpoint in the multivariable control system. Calibration tables include EGR reference percentage values ​​at low and high pressures, and the measured pressures are used by EGR reference module 210 to interpolate between these tables to determine an initial percentage EGR reference. A linear relationship between humidity and the percentage EGR reduction is used to adjust the EGR reference percentage for the current humidity.

[0065] Constraint module 220 implements a set of dilution phaser constraints 225, which issue a set of constraints in the operation of one or more cam phasers via multivariable controller 230. In an embodiment, the dilution phaser constraints 225 include control over one or more cam phasers. In an embodiment, constraint module 220 implements a process of combining humidity and EGR levels into a single dilution value, which is used to schedule cam phaser constraints. The dilution phaser constraints are based on three dilution setpoints: low dilution = k1 * low humidity + k2 * zero EGR, nominal dilution = k1 * high humidity + k2 * nominal EGR at high humidity, and maximum dilution = k1 * high humidity + k2 * maximum EGR at high humidity. Each dilution setpoint has a corresponding set of cam phaser maximum advance and maximum delay constraint tables. The current dilution value (k1 * humidity + k2 * EGR) is calculated and used for interpolation between the three sets of constraint tables. The output of the constraint tables is applied as constraints to multivariable controller 230. Adjustable cam phaser constraints (generated by constraint module 220) optimize engine performance while preventing poor combustion stability.

[0066] In this embodiment, the phaser reference module 215 determines the optimal cam phaser position based on engine temperature and EGR fraction. The phaser reference module 215 uses a set of multiple (i.e., three or more) cam phaser calibration tables, including tables containing cold values, warm values, and EGR values, to determine the U command 240 for the optimal phaser position.

[0067] In this embodiment, during the engine warm-up phase, the phaser reference module 215 processes a cold-warm calibrator mix from 0 to 1, which is used to apply an interpolation or estimation function between a set of values ​​included in the cold and warm cam phaser calibration tables. Once the cold-warm calibrator reaches 1, an EGR mixing factor is used to interpolate between the warm and EGR-equipped cam phaser tables. The EGR mixing factor is calculated by dividing the final %EGR reference by the nominal %EGR reference at the current humidity.

[0068] In this embodiment, the multivariable controller 230 uses a calculated percentage value of the EGR reference (from reference module 205) to implement multivariable engine torque / airflow control. The EGR reference value is received as input to determine the actuator position command for the engine. This EGR reference (Y, U reference) is based on values ​​from a calibration table of high and low air pressure values, along with adjustments made for humidity, engine coolant, and air temperature. Humidity regulation uses a simple formula to reduce EGR by multiplying by a coefficient for humidity changes. EGR and humidity have similar but different effects on combustion. The coefficient can be tuned to maintain constant effective dilution by changing the EGR according to humidity.

[0069] Figure 3An exemplary graph is shown illustrating a set of comparisons between humidity and EGR introduced in control modes for low dilution, nominal dilution, and maximum dilution, according to an embodiment. This comparison combines humidity and dilution in a single dilution value that limits the cam phaser to maximize engine performance. Figure 3 In the data, for the low dilution 302, the equivalent humidity is shown as low with no EGR. At the nominal dilution 304, for a dry condition with a humidity of 0.7%, the equivalent humidity to EGR ratio 310 shows a high percentage of EGR relative to the equivalent humidity. For a humidity condition with a humidity of 2.4%, the equivalent humidity to EGR ratio 315 shows a smaller percentage of EGR relative to the equivalent humidity.

[0070] Similarly, for the maximum dilution 306, a similar ratio 320 with a higher percentage of EGR relative to equivalent humidity and a humidity value of 0.7% is shown, and for a humidity condition with a humidity value of 2.4%, (coincidentally) a lower percentage of EGR relative to humidity with a ratio 330 is presented. The amounts of humidity and EGR are derived from the combined values ​​of humidity and EGR levels, subsequently from the values ​​of low dilution 302, nominal dilution 304, and maximum dilution 306. Figure 3 The single dilution value shown limits the range of permissible cam phasing.

[0071] The single dilution value is calculated using variables k1 and k2, summed together, as follows: Low dilution = k1 * Low humidity + k2 * Zero EGR, Nominal dilution = k1 * High humidity + k2 * Nominal EGR at high humidity, Maximum dilution = k1 * High humidity + k2 * Maximum EGR at high humidity. Each dilution setpoint has a corresponding set of cam phaser maximum advance and maximum delay constraint tables. The current dilution value (k1 * Humidity + k2 * EGR) is calculated and used for interpolation between the three constraint tables.

[0072] In an exemplary embodiment, the system via low dilution value, nominal value, and maximum dilution value simplifies the effects of humidity and EGR to a level that enables a multivariable controller ( Figure 2 The 230) limit the individual value of the cam phaser in order to maximize the engine's performance, stability, and efficiency.

[0073] In an exemplary embodiment, a multivariable torque controller can be implemented, which allows the airflow actuator (including a cam) to move away from a reference position to more optimally generate the desired torque. Constraints based on a single dilution value allow for acceptable combustion stability under varying EGR and ambient humidity conditions. The constraints also take into account the effects of humidity and EGR on combustion (which are determined by…). Figure 3(As shown in the chart), it has a similar effect on combustion, but to different degrees. To account for the different degrees, the effects of humidity and EGR (such as...) are also considered. Figure 3 (As shown) can be added together by first multiplying the humidity and EGR by scaling factors k1 and k2 respectively.

[0074] Figure 4 A calibration table is shown corresponding to the cam phaser constraints for low dilution 415, nominal dilution 425, and maximum dilution 435. Each dilution level has a calibration table for maximum intake phaser advance, maximum intake phaser delay, maximum exhaust phaser advance, and maximum exhaust phaser delay.

[0075] The current dilution value 405 is used at the low dilution value 410, the nominal dilution value 420, and the maximum dilution value 430 (i.e., at...). Figure 3 The interpolation between the dilution values ​​(low dilution value, nominal dilution value, and maximum dilution value) corresponding to the low dilution value 302, nominal dilution value 304, and maximum dilution value 306, and their respective calibration tables, are shown to determine the maximum propulsion constraint 440, the maximum delay constraint 445, the maximum propulsion constraint 450, and the maximum delay constraint 455 of the intake phaser.

[0076] In an exemplary embodiment, conventional cam phaser control can also be utilized by the value of a table used for the phaser setpoint under different conditions.

[0077] Figure 5 An exemplary diagram of a multivariable engine control according to various embodiments is shown, which utilizes three sets of exemplary calibration tables with cam phaser reference values ​​to control one or more cam phasers and EGR values;

[0078] exist Figure 5 In the multivariable engine control process 500, a calibration table 510 for cold camshaft phaser values, a calibration table 520 for warm camshaft phaser values, and a calibration table 530 with EGR phaser values ​​are included. A cold-warm calibrator 515 is configured to display engine temperature. After engine preheating, an EGR mixing factor 525 (i.e., EGR Y) is configured. ref Final percentage value / EGR Y ref (Nominal percentage value of the value). Values ​​from all three calibration tables are interpolated using interpolation functions 535 and 540, where the corresponding pairwise values ​​from the cold-warm calibration tables and the values ​​used to determine the cam phaser U command U. ref 545 (i.e., cam phaser reference target) warm-EGR calibration table.

[0079] If the cold-warm calibrator 515 has a value less than 1, then the estimation or interpolation used is based on the values ​​from the cold-warm calibration table pair; otherwise, it is based on the values ​​from the warm-EGR calibration table. Therefore, if the engine is not preheated, the cold and warm gauges are mixed to determine the camshaft phaser reference value. The cold-warm mixing factor is determined by the engine temperature and the calibration table. In an alternative exemplary embodiment, the camshaft phaser can be controlled independently of EGR, but the stability and efficiency of the engine's combustion process may be affected without considering EGR.

[0080] Figure 6 This is an exemplary diagram illustrating the process of calculating the percentage of EGR reference value used as a target setpoint by a multivariable control system, according to various embodiments.

[0081] exist Figure 6 The diagram illustrates a process 600 for interpolating percentage values ​​of EGR at low and high pressures using a multivariable controller. Figure 6 The diagram shows a calibration table 605 containing a high-pressure percentage value and another calibration table 615 containing a low-pressure percentage value. The low-pressure percentage value is adjusted by an interpolation function 610, which provides an interpolated pressure value. This interpolated pressure value is adjusted by an interpolation function 620 to interpolate a humidity value. The interpolated humidity value is then temperature-adjusted to produce a percentage value for EGR reference at output 640. In this embodiment, the values ​​in the calibration tables are base percentage values ​​for both low-pressure and high-pressure EGR references, and each value is associated with or a function of the engine's revolutions per minute (RPM) and required air per cylinder (APC). Output 640 is based on values ​​adjusted for both humidity and temperature.

[0082] In an embodiment, each value of the calibration table is adjusted by a moderate adjustment of interpolation function 620, which is -k multiplied by the current humidity minus the low humidity value (i.e., -k*(current humidity - low humidity)). This value is sent to temperature adjustment function 625, which multiplies it by the coolant temperature value or constant (*K) from table 630. coolanttemp )627, and then multiply by the charging temperature value or constant from Table 635 (*K) chargetemp )629, to generate the percentage value of the EGR reference output 640.

[0083] The measured atmospheric pressure 602 is used for interpolation (i.e., atmospheric pressure values ​​adjusted from the low / high atmospheric pressure calibration values ​​by interpolation function 610) of a set of values ​​from the low / high atmospheric pressure calibration table. This set of values ​​is then adjusted for humidity (i.e., the interpolated atmospheric pressure values ​​are then further interpolated based on a constant value multiplied by the amount of current humidity reduction) to determine an initial percentage value for applying the EGR reference using temperature adjustment function 625. A linear relationship between humidity and the EGR reduction percentage value is used to adjust the percentage value of the EGR reference for the current humidity. Figure 6 The humidity adjustment shown is a relatively simple formula that reduces EGR by multiplying by a coefficient "K" for humidity changes. EGR and humidity have similar, but different, effects on combustion. The coefficient "K" can be tuned to maintain constant effective dilution by changing the EGR according to humidity.

[0084] Figure 7 This is a combination of references and limitations associated with the EGR and cam phaser according to various embodiments. Figure 1-6 An exemplary flowchart of multivariable torque control for a vehicle is described, wherein the steps simplify the effects of humidity and EGR on a single dilution value used to limit cam phaser operation.

[0085] exist Figure 7 In task 705, the process is initiated by a multivariable controller implementing at least one processor, which is programmed with a set of instructions to determine a set of references associated with exhaust gas recirculation (EGR).

[0086] In an exemplary embodiment, the multivariable controller implements an algorithm that uses the value of engine temperature and at least one reference determined by a set of references associated with the EGR fraction to generate one or more commands for controlling a set of actuators. The multivariable controller is configured to optimize at least one cam phase position by control based on the generated commands, which apply to at least one actuator in the actuator group and exert an appropriate level of engine torque for vehicle propulsion. In an embodiment, the multivariable controller is configured to impose constraints based on humidity during vehicle operation and the amount of EGR introduced by the EGR valve to optimize the cam phase position of a set of cams associated with EGR valve operation, and to provide the amount of propulsion torque generated by the vehicle's engine according to instructions provided by the processor.

[0087] At task 710, a set of cam phasing, consisting of intake and exhaust cams combined with an external EGR, is implemented to enhance the control of the internal combustion engine. This control is based on a set of instructions in software that control the processor to simplify the various effects of humidity and EGR during vehicle phasing into a single value. This single value is used to generate at least one command to limit the operation of one or more cam phasers. The process also includes combining the humidity and EGR values ​​into a single dilution value as the basis for scheduling the constraints of this set of cam phasers.

[0088] At task 720, the process involves the processor tuning the values ​​of the set of cam phaser constraints to optimize engine performance while preventing undesirable combustion stability. The EGR reference value is based on one or more values ​​included in a set of calibration tables containing high and low pressure values, which are adjusted by the processor based on a set of values ​​associated with humidity, engine coolant, and air temperature. This adjustment includes the processor tuning coefficients used to adjust the EGR reference value based on this set of values ​​associated with humidity, engine coolant, and air temperature.

[0089] At task 730, during this process, the processor generates dilution values ​​to determine a set of phaser constraints by interpolating between a set of low dilution values, nominal dilution values, and maximum dilution values ​​and a corresponding set of calibration tables using the current dilution value as input. The determined phaser constraints include the maximum forward constraint of the intake phaser, the maximum backward constraint of the intake phaser, the maximum forward constraint of the exhaust phaser, and the maximum backward constraint of the exhaust phaser.

[0090] At task 740, during this process, in response to a high humidity level sensed in the operating environment, the processor reduces the amount of EGR as instructed to maintain a constant dilution value.

[0091] In mission 750, during the process, the processor issues control commands to control the operation of the EGR valve based on an algorithm that implements calculations of the percentage value of the EGR reference used as the basis for the target setpoint, in order to perform control over the amount of EGR; the percentage values ​​of the EGR reference at low and high atmospheric pressures are determined based on values ​​contained in a set of calibration tables; a set of values ​​associated with the measured atmospheric pressure is applied and an interpolation function is used to determine a set of values ​​from a set of calibration tables, on which the initial percentage value of the EGR reference is determined; and the percentage value of the EGR reference is adjusted according to the current humidity by using a linear relationship function between the current humidity value and the percentage value associated with the EGR reduction.

[0092] At task 760, during processing, the processor may be instructed to use a set of cam phaser values ​​from three sets of cam phaser calibration tables. These tables include: a first calibration table containing cold cam phaser values; a second calibration table containing warm cam phaser values; and a third calibration table containing EGR cam phaser values. Then, during engine warm-up, a cold-warm calibrator mix containing values ​​between 0 and 1 is performed, where the cold-warm calibrator mix values ​​provide the basis for applying an interpolation function between the cold and warm cam phaser values. Next, another mixing operation is performed upon EGR introduction, including calculating the EGR mixing factor by dividing the final percentage EGR reference by a nominal percentage value corresponding to the current humidity EGR reference. The EGR mixing factor provides the basis for applying an interpolation function between the warm and EGR cam phaser values; and generates a set of values ​​as reference target values ​​corresponding to cam phaser commands for the vehicle's engine to provide propulsion torque based on further instructions provided by the processor.

[0093] Therefore, methods, systems, and vehicles are provided to simplify the effects of humidity and EGR into a single value to maximize the vehicle's engine performance, stability, and efficiency by constraining or limiting cam phaser control.

[0094] It should be understood that the systems, vehicles, and methods described herein may differ from those depicted in the accompanying drawings and described herein. For example, Figure 1 100 vehicles Figure 1 Its control system and / or its components may vary in different embodiments. Similarly, it should be understood that the steps of process 700 may differ. Figure 1-6 The described steps, and / or the individual steps of process 700, can be performed simultaneously and / or in different ways. Figure 7 The order in which they occur

[0095] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that numerous variations exist. It should also be understood that the one or more exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of this disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing one or more exemplary embodiments. It should be understood that various changes can be made to the function and arrangement of the elements without departing from the scope of this disclosure as set forth in the appended claims and their legal equivalents.

Claims

1. A method for multivariable torque control of a vehicle, the method comprising: The configuration is set in a multivariable controller and the processor is programmed with a set of instructions to determine a set of references associated with exhaust gas recirculation (EGR); The processor implements an algorithm based on engine temperature and at least one reference determined by a set of references associated with the exhaust gas recirculation (EGR) to generate one or more commands for controlling a set of actuators. The processor optimizes at least one cam phase position by controlling, based on commands generated for at least one of the set of actuators, to apply an appropriate level of engine torque for vehicle propulsion. Based on the humidity during the internal combustion phase of vehicle operation and the amount of EGR introduced by the EGR valve, the processor limits the permissible range of cam phases of a set of cams associated with the operation of the EGR valve; and The vehicle's engine provides a certain amount of propulsive torque according to instructions provided by the processor.

2. The method according to claim 1, further comprising: The processor uses a set of cam phase control, including an intake cam and an exhaust cam combined with an external EGR, to enhance control of the internal combustion engine; as well as The processor simplifies the multiple effects caused by the humidity and EGR into a single value to generate at least one command to limit the operation of one or more cam phasers.

3. The method according to claim 2, further comprising: The processor combines the humidity and EGR values ​​into a single dilution value, which serves as the basis for scheduling a set of cam phaser constraints.

4. The method according to claim 3, further comprising: The processor tunes the values ​​of the set of cam phaser constraints to optimize engine performance while preventing poor combustion stability, wherein the EGR reference value is based on one or more values ​​contained in a set of calibration tables that include high and low pressure values.

5. The method according to claim 4, further comprising: The processor adjusts the EGR reference based on a set of values ​​associated with the humidity, engine coolant, and air temperature.

6. The method according to claim 5, further comprising: Based on the set of values ​​associated with the humidity, the engine coolant, and the air temperature, the processor tunes a coefficient to adjust the value of the EGR reference.

7. The method according to claim 6, further comprising: The dilution value also includes: The processor uses the current dilution value as input to interpolate between a set of dilution values, including low dilution value, nominal dilution value, and maximum dilution value, and a corresponding set of calibration tables to determine a set of phaser constraints, including maximum forward constraint of the intake phaser, maximum delay constraint of the intake phaser, maximum forward constraint of the exhaust phaser, and maximum delay constraint of the exhaust phaser.

8. The method according to claim 7, further comprising: In response to high humidity levels, the processor reduces the amount of EGR in order to maintain a constant dilution value.

9. The method according to claim 8, further comprising: The EGR valve is operated under the control of the processor through the following steps: The processor calculates a percentage value of the EGR reference, which serves as the basis for the target setpoint; The processor determines the percentage values ​​of the EGR reference at low and high atmospheric pressures based on the values ​​contained in the set of calibration tables; The processor applies a set of values ​​associated with the measured air pressure and uses an interpolation function to determine a set of values ​​from the set of calibration tables, on which an initial percentage value for the EGR reference is determined; as well as The processor adjusts the EGR reference percentage value based on the current humidity using a linear relationship function between the current humidity value and the percentage value associated with EGR reduction.

10. The method of claim 9, further comprising: A set of cam phaser values ​​is used from a first, second, and third set of cam phaser calibration tables, which include: a first calibration table containing cold cam phaser values; a second calibration table containing warm cam phaser values; and a third calibration table containing EGR cam phaser values. During engine preheating, a cold-warm calibrator mix containing values ​​between 0 and 1 is mixed, wherein the values ​​of the cold-warm calibrator mix provide the basis for applying the interpolation function between the cold cam phaser values ​​and the warm cam phaser values; When EGR is introduced, further mixing includes calculating the value of an EGR mixing factor by dividing the final percentage EGR reference by a nominal percentage value corresponding to the current humidity EGR reference, wherein the EGR mixing factor provides the basis for applying the interpolation function between the warm cam phaser value and the EGR cam phaser value; and A set of values ​​is generated as reference target values ​​corresponding to cam phaser commands, for use in determining the amount of propulsion torque provided by the engine of the vehicle according to instructions provided by the processor.

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