Control device and method for cylinder balance of an internal combustion engine

Abstract

A method (200) for operating an internal combustion engine (12) of a vehicle to maintain cylinder balance, comprising: distinguishing (204, 206) a first operating mode (202) corresponding to steady-state operation of the internal combustion engine (12) from a second operating mode (208) corresponding to transient operation of the internal combustion engine (12) based on a first operating parameter of the internal combustion engine (12); implementing (210) a first control strategy in the first operating mode (202) that provides cylinder balance; and implementing (212) a second control strategy in the second operating mode (208) that is different from the first control strategy to provide cylinder balance, the second control strategy using a dynamic factor based on a second operating parameter of the internal combustion engine (12);and wherein the second operating parameter comprises a moving average of the fuel requirement;

Description

TECHNICAL FIELDThe technical field relates to methods and controllers for operating an engine, and more particularly to the technical field of a method for operating an engine to maintain cylinder balance.BACKGROUNDAn internal combustion engine for an automotive vehicle generally includes an engine block defining at least one cylinder that receives a reciprocating piston coupled to rotate a crankshaft. The cylinder is closed by a cylinder head that cooperates with the reciprocating piston to define a combustion chamber. A fuel / air mixture is cyclically introduced into the combustion chamber and ignited, as a result of which mutual movements of the piston are generated by the expanding hot exhaust gases. Fuel is injected into each cylinder by a respective fuel injector. Fuel is supplied at high pressure from an injection line in fluid communication with a high pressure fuel pump to each fuel injector that increases the pressure of fuel received from a fuel source. Operation of the engine is generally controlled by one or more electronic control units (ECUs) operatively coupled to an array of sensors and actuators associated with the engine.Balanced combustion within the plurality of cylinders of a typical internal combustion engine is important for reliable, low vibration, and emissions compliant operation. A number of factors may affect cylinder-to-cylinder and cycle-to-cycle variability of the combustion process. Factors that affect cylinder-to-cylinder combustion variability include: mechanical designs such as stroke length, head and piston heights, seal and ring size, camshaft profile, fuel manifolds, shaft harmonics, etc.; engine and component conditions such as worn rings, light lifters, leaking fuel valves, degradation of spark plugs and ignition coils (in spark ignition engines), etc.; and combustion controls such as air / fuel ratio, spark timing, engine cooling, etc.The fuel injection system under the control of an ECU typically operates in closed loop integrated feedback, whereby the aforementioned factors contributing to cylinder imbalance can be compensated. However, during transient maneuvers such as cranking, high load / acceleration, and the like, cylinder balance may degrade during and after the transient maneuver because the closed loop integrated control does not predict the transient maneuver and requires time to converge. During this period of cylinder imbalance, there is potential for negative engine oscillations and emissions.DE 10 2005 030 870 A1 describes an apparatus and a method for controlling an internal combustion engine, in which a controller is assigned to each cylinder of the internal combustion engine, which controls a variable characterizing the combustion to a common setpoint value. Based on the output variables of the controllers, learning values are determined and used for pilot control of the controllers.DE 197 00 711 A1 describes a method for compensating the systematic error in injectors for an internal combustion engine. By means of a cylinder-selective measurement method for detecting the rough running, the actually injected fuel quantities are determined in the lower rotational speed range of the internal combustion engine and a cylinder-specific correction factor is calculated and stored from this. At higher rotational speeds and loads, the injection time and / or the injection start angle is then changed on the basis of the correction factors in a cylinder-specific manner and the smooth running of the internal combustion engine is thus improved.DE 10 2004 006 554 B3 describes a method for adjusting the cylinder with respect to the fuel injection quantities in an internal combustion engine. In order to adapt the injection quantity differences determined at an operating point in the lower rotational speed range by means of rough running control and dependent on an injection parameter to higher operating ranges, it is proposed to set the injection parameter for determining the injection quantity differences at the low operating point in each case to a value which deviates from the value applicable there in regular driving operation. In this case, the dynamics of the operating point variable with the respective injection parameter value are limited during the adaptation.DE 100 11 690 A1 describes an adaptation method for controlling the injection of a multi-cylinder internal combustion engine. Here, the individual cylinders are equalized lambda in homogeneous operation, to the effect that the same fuel mass is injected into all cylinders. In stratified-lean operation, torque equalization is carried out, in which the injection control is adapted in such a way that all cylinders output the same torque. At the beginning of this torque equalization, the last values of the lambda equalization are used, but not vice versa.Accordingly, it is an object of the invention to improve cylinder balance within an internal combustion engine, particularly during and after transient maneuvers.SUMMARYThe invention is defined by the claims.According to the embodiment(s) described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first operating parameter and the second operating parameter are the same operating parameters.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first operating parameter includes at least one of an engine speed and a moving average of the engine speed.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first operating parameter includes at least one of a fuel amount request and a moving average of the fuel request.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The second operating parameter includes at least one of an engine speed and a moving average of the engine speed.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The second operating parameter includes at least one of a fuel amount request and a moving average of the fuel request.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first control strategy is a closed loop integrated control.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The second control strategy is a closed loop integrated control.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first control strategy and the second control strategy are integrated closed loop controls.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The first control strategy and the second control strategy are the same.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second mode, a second control strategy is provided that is different than the first control strategy that provides cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. Cylinder balance is determined based on the intermediate mean effective pressure standard deviation of cylinder-to-cylinder.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. Cylinder balance is determined based on cylinder-to-cylinder exhaust emissions.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The cylinder balance results from the determination of fuel quantity data.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. Cylinder balance results from obtaining fuel quantity data and controlling a fuel injector according to the fuel quantity data.According to another exemplary embodiment described herein, a method of operating an internal combustion engine of a vehicle to maintain cylinder balance is provided. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine. The second operating mode is operable after the detection and for the duration of a transient operation of the internal combustion engine.According to another embodiment described herein, a computer program product is provided with program code stored on a non-transitory computer readable medium configured to provide cylinder balance when executed in a controller. A first mode corresponding to steady state operation of the engine is different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.According to another embodiment described herein, a vehicle includes an internal combustion engine having a plurality of cylinders and a quantity of fuel delivered to each cylinder by a corresponding fuel injector, the individual fuel injectors controlled via a controller operatively coupled to the individual fuel injectors. The controller is configured to provide cylinder balance with a first mode of operation corresponding to steady state operation of the engine different from a second mode of operation corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.According to another embodiment described herein, a vehicle includes an internal combustion engine having a plurality of cylinders and a quantity of fuel delivered to each cylinder by a corresponding fuel injector, the individual fuel injectors controlled via a controller operatively coupled to the individual fuel injectors. The controller is configured with a control program stored in a storage system to provide cylinder balance with a first mode corresponding to steady state operation of the engine different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.In another embodiment described herein, a control system is provided for controlling an internal combustion engine having a plurality of cylinders, wherein a quantity of fuel is delivered to each cylinder via a corresponding fuel injector, wherein the individual fuel injectors are controlled via a controller operatively coupled to the individual fuel injectors. The controller is configured to provide cylinder balance with a first mode of operation corresponding to steady state operation of the engine different from a second mode of operation corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.In another embodiment described herein, a control system is provided for controlling an internal combustion engine having a plurality of cylinders, wherein a quantity of fuel is delivered to each cylinder via a corresponding fuel injector, wherein the individual fuel injectors are controlled via a controller operatively coupled to the individual fuel injectors. The controller includes program code stored on a non-transitory computer readable medium associated with the controller. The control program, when executed in the controller, is configured to provide cylinder balance with a first mode corresponding to steady state operation of the engine and different from a second mode corresponding to transient operation of the engine based on a first operating parameter of the engine. In the first operating mode, a first control strategy is provided for the equilibrium of the cylinders. In the second operating mode, a second control strategy is provided, which differs from the first control strategy. The second control strategy uses a dynamic factor based on a second operating parameter of the internal combustion engine.BRIEF DESCRIPTION OF THE DRAWINGSThe present disclosure will be described hereinafter in connection with the following drawing figures, wherein like reference numerals designate like elements. FIG. 1 is a schematic illustration of a vehicle including an internal combustion engine operable in accordance with embodiments described herein; and FIG. 2 is a flow chart showing operation of an internal combustion engine according to embodiments described herein.DETAILED DESCRIPTIONThe following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application or uses of the present disclosure. Moreover, there is no obligation to limit any one of the theories set forth in the foregoing background or in the following detailed description. Exemplary embodiments will now be described with reference to the drawings, wherein conventional or well-known elements may be omitted for clarity.Some embodiments may include, as shown in FIG. 1, an automotive vehicle including an internal combustion engine (ICE) 12 having an engine block 14 defining a plurality of cylinders 16 with a piston 18 coupled to rotate a crankshaft. For each cylinder, a cylinder head cooperates with the piston 18 to define a combustion chamber 20. A fuel / air mixture is introduced into the combustion chamber 20 and ignited, as a result of which the piston 18 is caused to move reciprocally by the expanding hot exhaust gases. Fuel is provided by at least one fuel injector 28 and air is provided by at least one intake port of an intake manifold 22. Fuel is directed to injector 28 under high pressure from the fuel rail, which is connected in fluid communication with a high pressure rail for increasing the pressure of fuel from a fuel source. Each of the cylinders 16 has at least two valves that are actuated by a camshaft that rotates in unison with the crankshaft. The valves selectively allow air to enter the combustion chamber 20 and, alternatively, exhaust gases to escape through an exhaust port.The air may be carried to the intake passage / passages through the intake manifold 22. Intake passage 24 may direct ambient air to intake manifold 22. In other embodiments, a throttle body 26 may be installed to control the flow of air to the intake manifold 22. In still other embodiments, other blower systems may be used, e.g., a turbocharger having a compressor rotationally coupled to a turbine. Rotation of the compressor increases the pressure and temperature of the air in the passage 24 and the intake manifold 22, and an optional air cooler disposed in the passage 24 may be provided to decrease the temperature of the air.The exhaust system 30 may include an exhaust pipe 32 with an exhaust aftertreatment system 34, including one or more exhaust aftertreatment device(s). The exhaust after-treatment devices may be any possible device configured to change the composition of the exhaust gas. Some examples of exhaust after-treatment devices include, without limitation, catalytic converters (two and three way), such as diesel oxidation catalyst (DOC), lean NOx traps, hydrocarbon adsorber, and selective catalytic reduction (SCR) systems. The exhaust aftertreatment system 34 may further include a diesel particulate filter (DPF) that may be combined with the SCR to provide an SCRF system. Other embodiments may include an exhaust gas recirculation (EGR) system 40 installed between the exhaust manifold 42 and the intake manifold 22. The EGR system 40 may include an EGR cooler 44 for lowering exhaust temperatures in the EGR system 40. An EGR valve 46 controls the flow of exhaust gas in the EGR system 40.The vehicle may further include an electronic control unit (ECU) 50 in communication with one or more sensors and / or devices associated with the ICE 12. The ECU 50 may receive input signals from various sensors configured to generate signals related to various physical parameters related to the ICE 12. The sensors include, but are not limited to, a mass airflow and temperature sensor 56 that may be integrated with the throttle body 26 and a crankshaft position sensor 48. The sensors may also include, but are not limited to, a manifold pressure and temperature sensor, a combustion pressure sensor, coolant and oil level and temperature sensors, a fuel rail pressure sensor, a camshaft position sensor, an exhaust pressure sensor, an EGR temperature sensor, and an accelerator pedal position sensor. In addition, the ECU 50 may generate output signals for various controllers, the task of which is to control the operation of the ICE 12, including, without limitation, the fuel injectors, the flap nozzles 26, and the EGR valve 46. communication between the electronic controller 50 and the various sensors and devices is illustrated by dashed lines in FIG. 1, but some are omitted for clarity.Concerning the ECU 50, this apparatus may include a digital central processing unit (CPU) connected to a memory system 52, and an interface bus. The CPU is configured to execute the instructions stored in the memory system 52 as a program and to send and receive signals via the interface bus. The storage system 52 may include various types of memory, including optical memories, magnetic memories, solid state memories, and other non-volatile memories. A user interface 54, such as a driver information center (DIC), a touch screen interface, or any one or combination of display, switches, and buttons (not shown) to provide information to the operator and accept input from the operator, is operatively coupled to the ECU 50. The interface bus may be configured to modulate and send and receive analog and / or digital signals to and from the various sensors, controllers, and user interface 54. The program may embody the methods disclosed herein, which allows the CPU to execute the steps of these methods and control the ICE 12.The program stored in the storage system may be transmitted from the outside via a cable or a wireless interface. Outside the vehicle 10, it is normally visible as a computer program product, also referred to in the art as a computer readable medium or machine readable medium, to be understood as computer program code residing on a carrier, whether the carrier is transitory or non-transitory, with the consequence that the computer program product may be considered transitory or non-transitory.An example of a transitory computer program product is a signal, such as an optical signal, that is a transitory carrier for the computer program code. Carrying such computer program code may be accomplished by modulating the signal by a conventional digital data modulation technique such that binary data representing the computer program code is impressed on the transitory electromagnetic signal. Such signals may be used when computer program code is wirelessly transmitted over a WiFi connection from / to a laptop or other computing device.In the case of a non-transitory computer program product, the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory medium mentioned above, so that the computer program code is permanently or non-permanently retrievable stored in or on this storage medium. The storage medium may be of conventional type as is known in computer technology, such as flash memory, an application specific integrated circuit (ASIC), a CD, or the like.Instead of an ECU 50, the vehicle 10 may include various types of processors to provide the electronic logic, e.g., an embedded controller, an onboard computer, or any processing module, that could be deployed in a motor vehicle.FIG. 2 illustrates a control process 200 that may be provided as a non-transitory computer program product provided to and stored in the storage system, or may be a computer program stored in the storage system, or a shortened combination of control programs, electronic logic, and / or computers and processing devices deployed in the vehicle. The control process 200 is configured to provide steady state engine operating cylinder compensation in a first mode 202 and provide transient engine operating cylinder compensation after detection and for the duration of transient operation of the ICE 12 in a second mode 208.In non-limiting example embodiments, steady state operation may be delimited from transient operation based on one or more engine operating parameters. For example, the engine speed may be determined in a conventional manner using data from any number of sensors associated with the ICE 12 and operatively coupled to the ECU 50 such that a change in engine speed relative to a predetermined threshold is indicative of a steady-state to transient transition. In a further non-limiting example, a change in the moving average of the engine speed may be compared to a predetermined threshold. Likewise, the requested fuel quantity data may be monitored either in absolute terms or as a change in a moving average. As can be appreciated, a determination that a transition from steady state operation has occurred may be based on virtually any number and type of engine operating parameters or conditions, the foregoing examples being considered representative only.In the control process 200 shown in FIG. 2, at block 204, engine operating parameter data is obtained and at block 206, the engine operating parameter data is evaluated. If the engine operating data indicates transient engine operation, the transient mode 208 is initiated. Otherwise, a cylinder balance control 210 is implemented that provides a stationary cylinder balance control.In the steady state, cylinder balance is provided via a closed loop loop implemented as an integrated control strategy. The strategy may use the crankshaft position data obtained from the crankshaft position sensor 48 to determine the indicated average effective cylinder pressure (IMEP) to achieve an IMEP standard deviation between cylinders below a threshold. Cylinder balance is achieved by generating fuel amount correction data used to control the fuel injectors 28 to provide modified injected fuel amounts per cylinder to reduce the IMEP standard deviation to or below the target value. One or more exhaust emission measurements may also be considered to achieve a standard deviation of cylinder-to-cylinder exhaust emissions below a target value. Other stationary cylinder balance strategies and measurements may be used without limiting the generality of the present disclosure.After detecting the transient operation at block 206, the control process 200 enters the second mode 208. The second mode 208 is operable to provide cylinder balance after detection and for the duration of transient operation using a control strategy. In general, the control strategy associated with the second mode 208 uses a dynamic factor determined at block 212. In exemplary embodiments, the dynamic factor is determined based on one or more engine operating parameters. For example, the dynamic factor may be determined based on the change in engine speed, the change in moving average engine speed, the requested fuel amount, the change in requested fuel amount, and combinations of one of these parameters, or combinations of one or more of these parameters with one or more additional parameters. Advantageously, the dynamic factor may be based on the operating parameter or parameters evaluated to differentiate steady state operation from transient operation.In an exemplary embodiment, the second mode 208 may use the steady-state integral control strategy used in the first mode 202. In contrast to the steady state integral control strategy, in the second mode 208, the dynamic factor determined at 212 is used to modify one or more control parameters of the integral control strategy, e.g., adjusting the gain of the integral control to produce a modified control response. At block 214, cylinder balance control is implemented using the dynamic factor that enables transient operation of the cylinder balance. The second mode 208 remains active after the detection and duration of transient operation at block 216, but after steady state operation is restored, cylinder balance is achieved according to the first mode 202.According to embodiments described herein, cylinder balance within an internal combustion engine (ICE) is achieved using a cylinder balance control strategy. One or more ICE operating parameters, such as the requested fuel and / or the moving average engine speed, are used to distinguish steady-state operation from transient operation. In transient operation, a dynamic factor that is dependent on one or more ICE operating parameters and may advantageously be the requested fuel and / or moving average of engine speed may be used to determine the dynamic factor. A control strategy using the dynamic factor is then used to achieve cylinder balance.

Claims

A method (200) of operating an engine (12) of a vehicle to maintain cylinder balance, comprising: distinguishing (204, 206) a first mode of operation (202) corresponding to steady state operation of the engine (12) from a second mode of operation (208) corresponding to transient operation of the engine (12) based on a first operating parameter of the engine (12); implementing (210) a first control strategy in the first mode of operation (202) that provides cylinder balance; and implementing (212) a second control strategy in the second mode of operation (208) that is different from the first control strategy to provide cylinder balance, wherein the second control strategy uses a dynamic factor based on a second operating parameter of the engine (12); and wherein the second operating parameter comprises a moving average of the fuel demand.The method (200) of claim 1, wherein the first operating parameter comprises: at least one of an engine speed and a moving average of the engine speed; or at least one of a fuel amount request and a moving average of the fuel request; or at least one of an engine speed and a moving average of the engine speed.The method (200) of claim 1, wherein the first operating parameter and the second operating parameter are the same operating parameter.The method (200) of claim 1, wherein the second operating parameter comprises a fuel amount request.The method (200) of claim 1, wherein at least one of the first control strategy and the second control strategy comprises closed loop integrated control.The method (200) of claim 1, further comprising determining an intermediate mean effective pressure standard deviation of cylinder-to-cylinder to affect cylinder balance.The method (200) of claim 1, further comprising determining cylinder-to-cylinder exhaust emissions to affect cylinder balance.The method (200) of claim 1, further comprising determining fuel quantity data for affecting cylinder balance and controlling a fuel injector according to the fuel quantity data.The method (200) of claim 1, wherein the second mode of operation (208) is operable after the detection and for the duration of transient operation of the internal combustion engine (12).

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