System and method for operating an electrically assisted variable geometry turbocharger

Abstract

The present disclosure provides "systems and methods for operating an electrically-assisted variable geometry turbocharger." Methods and systems for operating an electrically-assisted turbocharger are provided. In one example, a method can include adjusting a position of a turbine of the turbocharger in response to a degree of power deficit, and operating an electric motor of the turbocharger based on the power deficit.

Description

Technical Field

[0001] This specification generally relates to methods and systems for controlling an electrically assisted variable geometry turbocharger coupled to an internal combustion engine. Background Technology

[0002] Engines can use turbochargers to provide boosted intake air, improving engine torque / power output density. A turbocharger can include a compressor coupled to an exhaust-driven variable geometry turbine (VGT). The airflow through the compressor can be adjusted by changing the geometry or position of the turbine blades to improve the compressor's operating range and turbocharger efficiency. However, operating a turbocharger alone may not meet high torque / power output demands.

[0003] One attempt to address the aforementioned problems includes an electrically assisted turbocharger. Barthelet et al. illustrate an exemplary method in US7779634. In this method, an electric motor is coupled to the turbocharger between the compressor and the turbine. The motor can provide additional boost to the engine to increase the turbocharger's operating range. The motor can also operate as a generator to save energy.

[0004] However, the inventors in this paper have recognized the potential problems with such systems. As an example, coupling an electric motor to a turbocharger can further complicate exhaust gas recirculation (EGR) rate and boost pressure control strategies. For instance, both the EGR rate and boost pressure can be affected by adjusting any of the actuators, including the VGT, the electric motor, and the EGR valve. Effective control strategies are needed to operate the actuators to track target EGR rates and target boost pressures with low electric assistance, short response times, and low emissions. Summary of the Invention

[0005] In one example, the above problem can be addressed by a method comprising: adjusting the position of a turbine coupled to a compressor to achieve desired turbine efficiency in response to insufficient power below a threshold, wherein the compressor supplies boost air to the engine and insufficient power is the difference between a target boost pressure and an actual boost pressure; and adjusting the turbine position based on a target flow rate of exhaust gas recirculated back into the engine in response to insufficient power above the threshold. In this manner, electrically assisted VGT can be controlled to meet target EGR rates and target boost pressures, while simultaneously reducing fuel consumption and emissions.

[0006] As an example, underpower can be calculated based on the target boost pressure and the measured boost pressure. In response to underpower, engine operation can switch between three operating modes. For example, in response to zero or negative underpower, engine operation can switch to mode one. In mode one, the VGT is adjusted to track the target boost pressure, and the EGR valve is adjusted to track the target EGR flow. The electric motor may not operate or may operate in regenerative mode to save energy. In response to positive underpower and below a threshold, engine operation can switch to mode two. In mode two, the VGT position can be adjusted to achieve the desired efficiency, which could be optimal (maximum) turbo efficiency, the electric motor can be adjusted to track the target boost pressure based on the adjusted VGT position, and the EGR valve can be adjusted to track the target EGR flow. In this mode, the boost pressure is adjusted via the VGT and the electric motor, while the EGR flow is adjusted via the EGR valve. By adjusting the VGT to the desired turbo efficiency, the energy consumption of the electrically assisted turbocharger can be reduced. In response to underpower equal to or above a threshold, engine operation can switch to mode three. In the third mode, both the VGT position and the EGR valve position can be adjusted simultaneously to track the target EGR flow. The electric motor can then operate to track the boost pressure based on the adjusted VGT position. Thus, the boost pressure is adjusted by the motor, while the EGR flow is adjusted by both the VGT and the EGR valve. By adjusting the VGT position to track the target EGR flow, the high EGR flow demand during periods of severe underpower (such as during momentary accelerator pedal depressing) can be met. By grouping the actuators differently in response to the degree of underpower, the engine can quickly reach the target operating point. Furthermore, fuel economy can be optimized by limiting electric assist and improving turbo efficiency.

[0007] It should be understood that the above description of the invention is provided to present some concepts further described in the detailed embodiments in a simplified form. This does not imply representation of key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed embodiments. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0008] Figure 1 An exemplary embodiment of a vehicle system is shown, the vehicle system including an engine with an electrically assisted variable geometry turbocharger.

[0009] Figure 2 It shows Figure 1 An illustration of an exemplary embodiment of one cylinder of a turbocharged engine.

[0010] Figure 3 The operation is shown Figure 2An exemplary method for an engine.

[0011] Figure 4 This is an exemplary mapping used to determine the underpower threshold.

[0012] Figure 5 It is a mapping used to determine the VGT location with desired turbine efficiency.

[0013] Figure 6 This is an exemplary block diagram of the first engine operating mode.

[0014] Figure 7 This is an exemplary block diagram of the second engine operating mode.

[0015] Figure 8 This is an exemplary block diagram of the third engine operating mode.

[0016] Figure 9 It shows the implementation Figure 3 The method is a timeline of parameters. Detailed Implementation

[0017] The following description relates to systems and methods for operating an engine with an electrically assisted variable geometry turbocharger. The turbocharger may include a variable geometry turbine and an electric motor coupled between a compressor and the variable geometry turbine. Examples of vehicle systems and engines are provided in [the following text is missing]. Figure 1 and Figure 2 As shown in the image. Figure 3 An exemplary method for operating an engine system is illustrated. Specifically, based on a comparison of insufficient power and a threshold, the engine can operate in one of three different modes. This can be determined according to... Figure 4 The mapping shown is based on online updates of engine operating condition thresholds. When the power is insufficient to zero or negative, the engine can adjust the thresholds accordingly. Figure 6 The block diagram shows operation in the first mode. When power is insufficient between zero and a threshold, the engine can... Figure 7 The block diagram operates in the second mode. In the second mode, the VGT is adjusted to be based on... Figure 5 The position is chosen to maximize turbo efficiency. When power is insufficient to reach a threshold, the engine can... Figure 8 The block diagram operates in the third mode. Parameters change over time in... Figure 9 As shown in the image.

[0018] Now for reference Figure 1An exemplary embodiment of vehicle system 100 is schematically illustrated. In one example, vehicle system 100 may be configured as a road motor vehicle. However, it should be understood that in other examples, vehicle system 100 may be configured as an off-road vehicle. In some examples, vehicle 100 may be a hybrid vehicle having multiple torque sources available for one or more wheels 76. In other examples, vehicle system 100 is a conventional vehicle with only an engine, or an electric vehicle with only one or more electric motors. In the illustrated example, vehicle system 100 includes an engine 10 and an electric motor 72. Electric motor 72 may be a motor or a motor / generator. When one or more clutches 73 are engaged, the crankshaft 40 of engine 10 and electric motor 72 are connected to the wheels 76 via a transmission 74. In the depicted example, a first clutch 73 is disposed between crankshaft 40 and electric motor 72, and a second clutch 73 is disposed between electric motor 72 and transmission 74. The controller 12 discussed herein can send signals to the actuators of each clutch 73 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft 40 from the motor 72 and its connected components, and / or connecting or disconnecting the motor 72 from the transmission 74 and its connected components. The transmission 74 can be a gearbox, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including in parallel, series, or series-parallel hybrid vehicles.

[0019] The motor 72 receives power from the traction battery 75 to provide torque to the wheels 76. The motor 72 can also operate as a generator to provide power to charge the traction battery 75, for example, during braking operations. In other examples, where the vehicle system 100 is a conventional vehicle with only an engine, the traction battery 75 can be a starter-lighting-ignition (e.g., SLI) battery that supplies electrical energy to the vehicle system 100.

[0020] In the depicted embodiment, engine 10 is a turbocharged engine including a turbocharger 13. The turbocharger 13 includes a turbine 116 positioned in an exhaust passage 35 and coupled to a compressor 110 positioned in an intake passage 42. The turbine 116 and compressor 110 may be coupled via shaft 19. Compressor 110 may be positioned upstream of a boost air cooler 18 (also referred to herein as a CAC) and an intake throttle valve 20. The turbine 116 can be driven (e.g., rotated) by expanding exhaust gas from engine 10, and the rotational energy of the turbine 116 can be transmitted via shaft 19 to rotate compressor 110.

[0021] An electric motor 111 can be coupled to both the compressor 110 and the turbine 116. In one embodiment, the electric motor can be coupled to the shaft 19 between the compressor 110 and the turbine 116. The electric motor can be controlled by a controller 12 to rotate the shaft 19 using current drawn from a battery (such as a traction battery 75). The electric motor can also be used as a generator and to charge the battery under certain operating conditions.

[0022] In one example, turbine 116 may be a variable geometry turbine with variable blade position, wherein the angle of the blades is adjustable to direct exhaust flow through the turbine blades in different patterns, thereby changing the turbine speed and boost pressure provided by turbocharger 13. The airflow through turbine 116 can be adjusted by changing the position of the turbine via actuator 117.

[0023] Engine 10 receives air via an airbox 44 including an air purifier 112 along an intake passage 42. The air is compressed by the compressor 110 of the turbocharger 13, and the compressed air is delivered to the intake passage 43. The compressed air passes through the intake passage 43, is cooled by a CAC 18, and passes through a throttle valve 20 before entering the intake manifold 22, at which point it enters engine 10. In other words, the compressor 110 is connected to the intake throttle valve 20 via a turbocharger air cooler 18, and the intake throttle valve 20 is connected upstream of the intake manifold 22. For example, the turbocharger air cooler can be an air-to-air or water-to-air heat exchanger. Figure 1 In the embodiment shown, the pressure of the air intake manifold is sensed by the manifold air pressure (MAP) sensor 124.

[0024] Compressor 110 may include a recirculation passage 80 spanning the compressor. The depicted example shows a compressor recirculation valve (CRV) 82 coupled across the recirculation passage 80, wherein actuation of the CRV 82 adjusts the flow rate through the recirculation passage 80. Warm compressed air from the compressor outlet may be recirculated back to the compressor inlet via the recirculation passage 80. In some embodiments, the compressor recirculation system may alternatively or additionally include a recirculation passage for recirculating (cooled) compressed air from the compressor outlet, downstream of a boost air cooler, to the compressor inlet, or for dissipating compressed air to the atmosphere (not shown). CRV 82 may be a continuously variable valve, wherein the valve position is continuously variable from a fully closed position to a fully open position. In some embodiments, the compressor recirculation valve 82 may remain partially open during boost engine operation to provide some degree of surge margin. In this document, the partially open position may be the default valve position. Increasing the opening of the compressor recirculation valve may include actuating (or energizing) a solenoid of the valve. Further discussion of exemplary CRV operation will be discussed herein.

[0025] One or more sensors may be coupled to the inlet of compressor 110 to determine the composition and condition of the air entering the compressor. For example, an intake air temperature (IAT) sensor 55 may be coupled to the intake passage 42 near the inlet of compressor 110 to estimate the compressor inlet temperature. As another example, a pressure sensor 56 may be coupled to the compressor inlet to estimate the pressure of the air entering the compressor. In another example, a mass air flow (MAF) sensor 57 may also be coupled to the compressor inlet to estimate the amount of air entering the engine. Other sensors may include, for example, an air-fuel ratio sensor, a humidity sensor, etc. In other examples, one or more of the compressor inlet conditions (such as humidity, temperature, etc.) may be inferred based on engine operating conditions. Sensors may estimate the intake air received from the intake passage at the compressor inlet and the condition of the air recirculated from upstream of the CAC. A throttle inlet pressure (TIP) sensor 58 or other suitable sensor may be coupled downstream of compressor 110 and upstream of throttle valve 20 to measure boost pressure.

[0026] Intake manifold 22 passes through a series of intake valves (see reference) Figure 2 (Further description) is connected to a series of combustion chambers 30. The combustion chambers are also connected via a series of exhaust valves (see reference). Figure 2 (Further description) Connected to exhaust manifold 36. In the depicted embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, exhaust manifold 36 may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections allows effluent from different combustion chambers to be directed to different locations within engine system 10. Sensor 125 may be connected to the exhaust manifold for measuring exhaust flow.

[0027] Combustion chamber 30 can be accessed via the fuel system (reference) Figure 2 (Further description) One or more fuels, such as gasoline, alcohol-fuel blends, diesel, biodiesel, compressed natural gas, etc., are supplied. Fuel can be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Direct injection involves injecting fuel directly into the combustion chamber, while port injection delivers a fuel spray into the intake manifold, where the fuel spray mixes with the intake air before entering the combustion chamber. This example may include multiple direct fuel injectors 66 and port fuel injectors 67. Combustion can be initiated in the combustion chamber via spark ignition and / or compression ignition.

[0028] Engine 10 may also include one or more exhaust gas recirculation (EGR) passages for recirculating a portion of the exhaust gas from the exhaust manifold to the intake manifold. By recirculating some of the exhaust gas, engine dilution can be affected, which can improve engine performance by reducing engine knock, peak cylinder combustion temperature and pressure, throttling losses, and NOx emissions. In the depicted example, exhaust gas may be recirculated from exhaust manifold 36, upstream of turbine 116, via high-pressure EGR passage 84 to intake manifold 22, compressor 110, and throttle valve 20. This configuration may be referred to as a high-pressure (HP) EGR system. High-pressure EGR passage 84 may include an HP-EGR valve 86 for controlling HP EGR flow and an EGR cooler 88 for delivering previously cooled exhaust gas into the intake manifold. In a further example, exhaust gas may be recirculated from exhaust passage 35, downstream of turbine 116, via low-pressure (LP) EGR passage 190 to intake passage 42, upstream of compressor 110, to provide LP-EGR. The exhaust flow rate in the LP-EGR passage is controlled via the LP-EGR valve 52. The amount of EGR supplied to the intake passage can be varied by the controller 12 via the LP-EGR valve 52 and the HP-EGR valve 86. The controller can attribute a certain amount of desired EGR flow to the HP-EGR and LP-EGR passages. As an example, if the desired EGR flow is higher than the HP-EGR capacity, the controller fully opens the HP-EGR valve 86 and adjusts the opening of the LP-EGR valve 52 to provide the desired EGR flow.

[0029] Engine system 100 may also include control system 14, which includes controller 12. Controller 12 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As an example, sensors 16 may include a MAP sensor 124, an exhaust flow sensor 125, an exhaust temperature sensor 128, an exhaust pressure sensor 129, an intake air temperature sensor 55, a compressor inlet pressure sensor 56, a manifold air flow sensor 57, and a throttle inlet pressure sensor 58. Other sensors, such as additional pressure, temperature, air / fuel ratio, and composition sensors, may be coupled to various locations within engine system 10. In one example, compressor speed sensor 54 may be coupled to compressor 110 to determine the compressor's rotational speed. According to a non-limiting embodiment, compressor speed sensor 54 may be a passive eddy current sensor. In one example, compressor speed sensor 54 may be a passive eddy current sensor. Actuator 81 may include, for example, a throttle valve 20, a compressor recirculation valve 82, a direct fuel injector 66, an intake manifold fuel injector 67, a turbine actuator 117, a high-pressure EGR valve 86, and an electric motor 111.

[0030] The control system 14 can be coupled to the navigation system 154 and the wireless communication device 152. The navigation system 154 determines the position of the vehicle system 100 at ignition and at any other time. The position of the vehicle system 100 estimated by the navigation system 154 (e.g., the vehicle's GPS coordinates) can be stored at the control system 14 for use during driving cycles. The navigation system can be connected to an external server and / or a network cloud 160 via the wireless communication 150. The navigation system 154 can determine the current position of the vehicle system 100 and obtain traffic and road condition data from the network cloud 160 for use when controlling engine operation. In addition, based on the destination selected by the operator, the navigation system 154 can provide various route options and then provide turn-by-turn instructions for navigating the vehicle system from its current position (e.g., origin) to the selected destination.

[0031] The controller 12 can also receive input data via wireless communication device 152 using wireless communication 150 from one or more of the following: network cloud 160, vehicle-to-vehicle (V2V) technology 170, and vehicle-to-infrastructure (V2I) technology 180. V2V 180 can allow the control system 14 to communicate with other similarly equipped vehicles, including wireless communication device 172, to collect information about traffic and road conditions from infrastructure including wireless communication device 182. In one example, V2V can indicate vehicle speeds along a predicted route, such as whether other vehicles can stop ahead, or whether there is stop-and-go traffic along the current route relative to another route. In another example, V2I can indicate an impending red traffic light or a traffic accident along a predicted route. In this way, the vehicle system 100 can communicate with remote sources (e.g., external network cloud, other vehicles, infrastructure) using one or more technologies (e.g., wireless communication, navigation system, GPS, V2V, V2I).

[0032] Various types of data, including but not limited to gradient map data and upcoming traffic conditions, can be exchanged between the vehicle and the network cloud, and this data can be used to control vehicle operation. In one example, based on input from navigation system 154, controller 12 can identify driving patterns. Specifically, controller 12 can "learn" that the vehicle operator takes the same route to work each weekday morning. The controller can store data about the route, including road gradient information and / or expected traffic conditions, and together with the learned driver model, can proactively control compressor situation handling to avoid predicted congestion or predicted surge conditions. The learned driver model can be developed by storing data related to the vehicle operator's habits. For example, over several weekday commutes, the controller can learn that during the morning commute, the driver exhibits relatively moderate driving habits (e.g., indicated by gradual and infrequent actuation of the accelerator and brake pedals, resulting in gradual acceleration and sporadic braking). This type of driving behavior is referred to herein as a "moderate driver pattern," which can lead to low-energy-density actuation of the accelerator pedal.

[0033] In this way, the vehicle controllers 12 can communicate with the vehicle controllers of other vehicles via their respective navigation systems 154, via wireless communication devices 152 and / or via other forms of vehicle-to-vehicle (V2V) technology.

[0034] Controller 12 can respond to processed input data received from various sensors, based on instructions stored in the controller's memory or code programmed therein (which corresponds to one or more routines, such as...) Figure 3 In an exemplary method 300, actuator 81 is used. As an example, controller 12 can determine that the compressor is underpowered based on measurements from pressure sensor 58 and adjust turbine actuator 117 and electric motor 111 to adjust the boost pressure.

[0035] Now for reference Figure 2 This shows an internal combustion engine (such as...) Figure 1 An exemplary embodiment 200 of the combustion chamber (e.g., cylinder) of an engine 10. This can be modified for previously... Figure 1The components described herein are similarly numbered. Engine 10 can receive control parameters from a control system including controller 12, as well as input from vehicle operator 230 via input device 232. In this example, input device 232 includes an accelerator pedal and a pedal position sensor 234 for generating a proportional pedal position signal PP. The cylinder (also referred to herein as a “combustion chamber”) 30 of engine 10 may include combustion chamber walls 236, in which a piston 238 is located. Piston 238 may be coupled to crankshaft 40 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 40 may be coupled to at least one drive wheel of the vehicle system via a transmission system.

[0036] Cylinder 30 can receive intake air via intake passage 42, intake passage 43, and intake manifold 22. In addition to cylinder 30, intake manifold 22 can also communicate with other cylinders of engine 10. In some embodiments, one or more intake passages may include a supercharging device, such as a turbocharger or supercharger. For example, Figure 2 An engine 10 equipped with a turbocharger 13 is shown. The turbocharger 13 includes a compressor 110 disposed between an intake passage 42 and an intake passage 43, and an exhaust turbine 116 disposed between an exhaust manifold 36 and an exhaust passage 35. The compressor 110 may be at least partially powered by the exhaust turbine 116 via a shaft 19, wherein the supercharging device is configured as a turbocharger. The compressor 110 may also be powered by an electric motor 111 coupled to the shaft 19. The electric motor 111 may output motor power based on a control signal received from a controller 12. A throttle valve 20 may include a throttle plate 264 and may be disposed along the engine's intake passage to change the flow rate and / or pressure of the intake air supplied to the engine cylinders. For example, the throttle valve 20 may be disposed downstream of the compressor 110, or alternatively, may be disposed upstream of the compressor 110.

[0037] In addition to cylinder 30, exhaust manifold 36 can also receive exhaust gas from other cylinders of engine 10. Exhaust sensor 228 is shown coupled upstream of emission control device 278 to exhaust manifold 36; however, it should be understood that it can be located at other locations in the exhaust system. Exhaust gas sensor 228 can be selected from various suitable sensors for providing an indication of the exhaust gas air / fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a dual-state oxygen sensor or EGO (as depicted), HEGO (heated EGO), NOx, HC, or CO sensors. Emission control device 278 can be a three-way catalytic converter (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0038] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 30 is shown as including at least one lift-type intake valve 250 and at least one lift-type exhaust valve 256 located in the upper region of cylinder 30. In some embodiments, each cylinder of engine 10 (including cylinder 30) may include at least two lift-type intake valves and at least two lift-type exhaust valves located in the upper region of cylinder.

[0039] The intake valve 250 can be controlled by the controller 12 via cam actuation through the cam actuation system 251. Similarly, the exhaust valve 256 can be controlled by the controller 12 via the cam actuation system 253. The cam actuation systems 251 and 253 can each include one or more cams and can utilize one or more of the following: a cam profile changing (CPS) system, a variable cam timing (VCT) system, a variable valve timing (VVT) system, and / or a variable valve lift (VVL) system, which can be operated by the controller 12 to change valve operation. Whether electronically actuated or cam-actuated, the opening and closing timing of the exhaust and intake valves can be adjusted according to desired combustion and emission control performance requirements. The operation of the intake valve 250 and exhaust valve 256 can be determined by valve position sensors (not shown) and / or camshaft position sensors 255 and 257, respectively. In an alternative embodiment, the intake and / or exhaust valves can be controlled by electric valve actuation. For example, cylinder 30 may alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation, including a CPS and / or VCT system. Additionally, the VCT system may include one or more VCT devices (not shown) that can be actuated to adjust the timing of the intake and exhaust valves to provide reduced positive intake and exhaust valve overlap. That is, the intake and exhaust valves will open for a shorter duration and will avoid opening simultaneously for a portion of the intake stroke. In other embodiments, the intake and exhaust valves may be controlled by a common valve actuator or actuation system, or a variable valve timing actuator or actuation system.

[0040] In some embodiments, each cylinder of engine 10 may be configured with one or more injectors for delivering fuel to cylinder 30. As a non-limiting example, cylinder 30 is shown including two fuel injectors 66 and 67. Fuel injectors 66 and 67 may be configured to deliver fuel received from fuel system 288 via a high-pressure fuel pump and fuel rail. Alternatively, fuel may be delivered at a lower pressure via a single-stage fuel pump, in which case the timing of direct fuel injection during the compression stroke may be more restrictive than when using a high-pressure fuel system. Additionally, the fuel tank may have a pressure sensor that provides a signal to controller 12.

[0041] Fuel injector 66 is shown directly coupled to cylinder 30 to inject fuel directly therein in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic actuator 268. In this manner, fuel injector 66 provides so-called direct injection of fuel into combustion cylinder 30 (hereinafter referred to as "DI"). Although Figure 2 An injector 66 is shown positioned on one side of cylinder 30, but the injector could alternatively be located on top of the piston, such as near spark plug 292. This location can improve mixing and combustion when the engine is operating with alcohol-based fuels, due to the lower volatility of some alcohol-based fuels. Alternatively, the injector could be located on or near the intake valve to improve mixing.

[0042] Fuel injector 67 is shown arranged in the intake manifold 22 rather than in the cylinder 30, and is configured to provide so-called fuel intake manifold injection (hereinafter referred to as "PFI") into the intake passage upstream of the cylinder 30. Fuel injector 67 can inject fuel received from fuel system 288 in proportion to the pulse width of signal FPW-2 received from controller 12 via electronic actuator 271. Note that a single electronic actuator 268 or 271 can be used for two fuel injection systems, or multiple actuators can be used, such as electronic actuator 268 for fuel injector 66 and electronic actuator 271 for fuel injector 67, as depicted.

[0043] During a single cycle of a cylinder, fuel can be delivered to the cylinder via two injectors. For example, each injector can deliver a portion of the total fuel injected for combustion in cylinder 30. Therefore, even for a single combustion event, the injected fuel can be injected from the intake manifold and the direct injector at different timings. Furthermore, for a single combustion event, multiple injections can be performed on the delivered fuel per cycle. These multiple injections can be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0044] As mentioned above, Figure 2 Only one cylinder of a multi-cylinder engine is shown. Therefore, each cylinder can similarly include its own set of intake / exhaust valves, fuel injectors, spark plugs, etc. It should be understood that engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more. Additionally, each of these cylinders can include a reference cylinder 30 via... Figure 2 Some or all of the various components described and depicted.

[0045] The engine may also include one or more exhaust gas recirculation passages. In the depicted embodiment, exhaust gas may be recirculated from exhaust passage 35 (e.g., downstream of turbine 116) to intake passage 42 (e.g., upstream of compressor 110) via LP-EGR passage 190. Furthermore, an EGR sensor 245 may be disposed within EGR passage 190 and may provide indications of one or more of exhaust gas pressure, temperature, and concentration. Other non-limiting exemplary EGR configurations may include HP-EGR (such as...). Figure 1 The HP-EGR channel 84 and the HP-EGR sensor arranged in the HP-EGR channel are used to measure one or more of the pressure, temperature and concentration of the exhaust gas.

[0046] The controller 12 is shown as a microcomputer, which includes a microprocessor unit 206, an input / output port 208, an electronic storage medium for executable programs and calibration values ​​(shown in this particular example as a read-only memory chip 210), a random access memory 212, a keep-alive memory 214, and a data bus. The controller 12 can receive data from... Figures 1 to 2 Various signals from various sensors, and employing Figures 1 to 2 Various actuators adjust engine operation based on received signals and instructions stored in the controller's memory. In addition to the signals previously discussed, the controller 12 may also receive the following signals: a measurement of the engine coolant temperature (ECT) from a temperature sensor 216 coupled to the cooling sleeve 218; a surface ignition sensing signal (PIP) from a Hall effect sensor 220 (or other type) coupled to the crankshaft 40; a throttle position (TPS) from a throttle position sensor; and a manifold absolute pressure signal (MAP) from sensor 224. An engine speed signal (RPM) can be generated by the controller 12 from the PIP signal. An indication of vacuum or pressure in the intake manifold can be provided using the manifold pressure signal MAP from the manifold pressure sensor. Other sensors may include a fuel level sensor and fuel composition sensors coupled to one or more fuel tanks in the fuel system. The storage medium read-only memory chip 210 can be programmed with computer-readable data representing instructions executable by the microprocessor unit 206 to perform the methods described below and other contemplated but not specifically listed variations.

[0047] Figure 3 A method 300 for adjusting an actuator to track a target boost pressure and a target EGR flow is shown, the adjustment including adjusting the turbine (such as...) Figures 1 to 2 Turbine 116) position, HP-EGR valve (such as Figure 1 The position of the EGR valve 86 and the motor (such as Figure 1(Electric motor 111). In response to insufficient power, the actuators are grouped in different ways for boost pressure control or EGR control.

[0048] Instructions for executing method 300 and the remaining methods included herein can be generated by the controller based on data stored in the controller (such as...). Figures 1 to 2 The controller 12) stores instructions in its memory and combines them with those from sensors in the engine system (such as those mentioned above). Figures 1 to 2 The controller uses signals received by the described sensors to perform actions. According to the method described below, the controller can employ the engine actuators of the engine system to adjust engine operation.

[0049] At 302, method 300 estimates and / or measures engine operating conditions, including but not limited to engine speed, fuel quantity, fuel pressure, operator torque demand, engine coolant temperature (ECT), air pressure (BP), boost pressure, intake manifold pressure (boost pressure), exhaust manifold pressure, mass airflow rate (MAF), exhaust flow rate, accelerator pedal position (PP), EGR flow rate, and EGR flow rate, which can be referenced... Figure 1 and Figure 2 The output measurement and / or estimation of the corresponding sensor are described.

[0050] At point 304, the desired engine operating point can be determined. The desired operating point can include target boost pressure, target exhaust flow rate, target turbine speed, and target EGR flow rate or EGR rate. As an example, the desired engine operating point can be determined based on operator input. As another example, the desired engine operating point can be automatically generated by the controller or an external source such as the cloud based on road conditions, vehicle route, engine operating conditions, and driving habits.

[0051] At point 308, method 300 determines whether the turbocharger requires auxiliary power. Auxiliary power may be needed in response to insufficient positive power, where the target compressor output power is higher than the actual compressor output power. If auxiliary power is required, the controller can operate a motor to make the shaft (such as...) Figure 1The shaft 19 rotates and increases the compressor power output. In one embodiment, compressor power deficiency can be calculated based on the difference between the target boost pressure determined at 304 and the boost pressure measured at 302. In another embodiment, compressor power deficiency can be determined based on the target boost pressure and the current VGT position. For example, the target compressor power can be determined based on the target boost pressure, and the actual compressor power can be determined based on the turbine power, which can be calculated based on the actual VGT position and exhaust flow conditions (measured or estimated flow rate or temperature or pressure). Compressor power deficiency is determined as the difference between the target compressor power and the actual compressor power. If compressor power deficiency is negative, no auxiliary power is required, and the engine operates in the first mode 310. Otherwise, method 300 moves to 309 and operates the motor to provide auxiliary power.

[0052] In the first engine operating mode of the 310, the VGT position is adjusted to track the target boost pressure, and the EGR valve is adjusted to track the EGR flow. The VGT position is not adjusted to track the EGR flow, and the EGR valve is not adjusted to track the boost pressure. The motor may be inactive or operate in regenerative mode. Figure 6 An exemplary block diagram for operating the engine in a first operating mode is shown.

[0053] At 309, method 300 determines the underpower threshold TH. In one embodiment, the threshold TH can be determined based on the measured / estimated actual boost pressure and the measured engine speed at 302. Figure 4 An exemplary mapping for determining the threshold TH is shown. The x-axis is engine speed, and the y-axis is boost pressure. Line 401 indicates the maximum boost pressure that the engine can provide at a specific boost speed. In one embodiment, lines 402, 403, 404, and 405 are exemplary thresholds. The threshold TH is the same along each line (402 to 405). As shown by arrow 406, the threshold increases with increasing engine speed and boost pressure. That is, threshold 405 > threshold 404 > threshold 403 > threshold 402. In one embodiment, a threshold can be assigned to both the boost pressure range and the engine speed range. For example, the threshold in each region of 410, 420, 430, and 440 can be the same. The assigned threshold can be increased as shown by arrow 406.

[0054] The threshold can be further adjusted based on motor type, vehicle driving mode, and battery state of charge. For example, the threshold may be limited by the maximum motor power the motor is designed to deliver. The threshold can be lower in Eco driving mode compared to Sport driving mode. The threshold can decrease as the battery state of charge increases.

[0055] At 316, method 300 compares the insufficient power with a insufficient power threshold TH determined at 309. If the insufficient power is less than the threshold TH, the engine operates in the second mode 318. If the insufficient power is equal to or greater than the threshold TH, the engine operates in the third mode 328.

[0056] In mode 318, the VGT position is first adjusted to achieve the desired (e.g., maximum) turbo efficiency, and then the motor is adjusted to provide additional power to meet the target boost pressure. The EGR valve is adjusted based on the target EGR flow rate. EGR control is separate from VGT position control. By adjusting the VGT to a position with the desired turbo efficiency (the maximum achievable in one example), motor power consumption can be reduced.

[0057] At 320°, the VGT position can be calculated based on the turbine's blade ratio to obtain the desired turbine efficiency. The desired turbine efficiency can be the maximum turbine efficiency achievable at a specific blade ratio. The blade ratio can be calculated based on the target exhaust flow rate and turbocharger speed. In one example, the turbocharger speed can be measured or estimated. In another example, the turbocharger speed can be estimated based on the target boost pressure. Figure 5 An exemplary profile diagram of turbine efficiency relative to VGT position and blade ratio is shown. The y-axis is the VGT position, and the x-axis is the blade ratio. The profile illustrates the turbine efficiency. Maximum turbine efficiency is shown by line 510. Therefore, given the blade ratio, efficiency can be calculated based on... Figure 5 To determine the VGT position with optimal (maximum) turbo efficiency. Alternatively, it can be determined via a method based on... Figure 5 A constructed lookup table is used to determine the VGT position with the desired turbine efficiency. Method 300 also updates the compressor underpowerment based on the VGT position calculated at 320 and the target boost pressure. Figure 7 An exemplary block diagram for operating the engine in a second operating mode is shown.

[0058] At 322, the actual EGR flow rate is estimated or measured. As an example, the EGR flow rate can be estimated based on boost pressure, exhaust manifold pressure or flow rate, and the opening of the EGR valve. As another example, the EGR flow rate can be measured using a sensor connected to the high-pressure EGR channel.

[0059] At 324, the VGT is actuated to move to the calculated VGT position, the motor is operated to supply updated power, and the EGR valve is adjusted to track the target EGR flow based on the EGR flow estimated at 322.

[0060] If the power deficit is equal to or greater than the threshold TH, the engine operates in mode 328. High power deficit can lead to insufficient EGR flow. For example, in response to a momentary press of the accelerator pedal, boost pressure can increase faster than exhaust pressure with aggressive power assist. Changes in the pressure difference across the high-pressure EGR passage can reduce the EGR flow rate, resulting in insufficient EGR flow. Operating the EGR valve alone may not be sufficient to meet the increased EGR flow requirements. To overcome insufficient EGR, the VGT and EGR valve can be adjusted together to increase EGR flow, and the motor can be adjusted to track the target boost pressure based on the target VGT position. Compared to mode 2, where VGT is adjusted to achieve desired turbo efficiency to reduce power consumption, here fuel economy is sacrificed to reduce emissions and improve driving performance. Figure 8 An exemplary block diagram for operating the engine in a third operating mode is shown.

[0061] At 330, method 300 estimates the actual EGR flow similar to that at 322.

[0062] At position 332, the VGT and EGR valve position are calculated based on the estimated EGR flow rate and the target EGR flow rate. Underpowerment can then be determined based on the calculated VGT position and the target boost pressure.

[0063] At position 334, adjust the VGT and EGR valves to the calculated positions and actuate the motor to compensate for insufficient power.

[0064] At 336, method 300 checks whether the boost pressure and EGR flow rate / flow targets have been met. For example, the boost and EGR targets are met when the error between the actual boost pressure and the target boost pressure is within a threshold percentage range (such as 5%) of the target boost pressure, and the error between the actual EGR flow rate and the target EGR flow rate is within a threshold percentage range (such as 5%) of the target EGR flow rate. Method 300 terminates when the boost and EGR targets are met. Otherwise, method 300 returns to 302 to estimate the engine operating condition.

[0065] Figure 6 An exemplary block diagram for operating the engine in a first operating mode is shown. The VGT control module 610 outputs a VGT position signal to the VGT actuator (such as...) of the engine system 630 based on the target exhaust flow rate 602 and the difference between the target boost pressure 601 and the actual boost pressure 605. Figure 1 The actuator 117). The EGR control module 620 outputs the EGR control signal 608 to the EGR valve (such as the actuator 117) of the engine system 630 based on the difference between the target EGR flow rate 606 and the actual EGR flow rate 609. Figure 1 The high-pressure EGR valve 86). This can be achieved via sensors (such as...) Figure 1 The pressure sensor 58 measures the actual boost pressure 605. This can be based on manifold air pressure (e.g., via...). Figure 1 The flow rate is measured by sensor 124), and the exhaust manifold flow rate is measured (e.g., via...). Figure 1 The actual EGR flow rate is estimated by measuring the EGR valve opening (using sensor 125). Alternatively, the actual EGR flow rate can be measured by a sensor connected to the high-pressure EGR channel.

[0066] In this manner, the VGT position and EGR valve position are controlled independently based on two different feedback control loops. Specifically, the VGT position is adjusted based on the target boost pressure, and the EGR valve position is adjusted based on the target EGR flow rate. The VGT control module 610 and the EGR control module 620 can be PID controllers.

[0067] Figure 7 An exemplary block diagram for operating the engine in a second operating mode is shown. The VGT control module 720 outputs a VGT position control signal 705 to the VGT actuator of the engine system 740 based on a target boost pressure 701 and a target exhaust flow rate 702. The VGT control module first calculates the blade speed ratio based on the target boost pressure 701 and the target exhaust flow rate 702, and then via, for example... Figure 5 The mapping or lookup table shown determines the VGT position that leads to the desired turbo efficiency. A VGT position control signal is generated based on the target boost pressure, rather than the target EGR flow rate. The VGT position control signal 705 can be determined based on the identified VGT position. The motor control module outputs a motor control signal 707 to the motor (such as...) of the engine system 740 based on the target boost pressure 701 and the VGT position control signal 705. Figure 1 The electric motor 111). For example, the motor control module can calculate the actual boost pressure based on the VGT position control signal 705, and then calculate underpower based on the target boost pressure and the actual boost pressure. The motor control signal 707 can then be determined based on the calculated underpower. The EGR control module 730 outputs an EGR control signal to the EGR valve (such as the target EGR valve 111) of the engine system 740 based on the difference between the target EGR flow rate 703 and the actual EGR flow rate 704. Figure 1 HP-EGR valve 86). EGR control module 730 can be a PID controller. It can be controlled via sensors (such as... Figure 1 The sensor 58 is used to measure the actual boost pressure 708.

[0068] In this way, the boost pressure can be adjusted via open-loop control, while the EGR flow rate is adjusted via closed-loop control. The boost pressure is controlled by the VGT and the motor, while the EGR is controlled by the EGR valve. In other words, the VGT and the motor are grouped together for boost control, and the EGR valve is operated for EGR flow rate control.

[0069] Figure 8 An exemplary block diagram for operating the engine in a third operating mode is shown. Based on both the target exhaust flow rate 802 and the difference 809 between the target EGR flow rate 803 and the actual EGR flow rate 808, the EGR control module 820 outputs a VGT position control signal 805 to the VGT actuator of the engine system 830 and an EGR valve position control signal to the EGR valve of the engine system 830. Thus, both the VGT position and the EGR valve are adjusted based on EGR flow feedback to track the target EGR flow rate. The EGR control module 820 may be a PID controller. The motor control module 810 outputs a motor control signal 804 to the motor of the engine system 830 based on the target boost pressure 801 and the VGT position control signal 805. The motor control module may first calculate the turbine power based on the VGT position control signal, and then determine compressor power deficiency based on the target boost pressure and the calculated turbine power. The motor control signal is then calculated based on the compressor power deficiency.

[0070] In this way, the actual boost pressure 807 can track the target boost pressure 801, and the actual EGR flow rate 808 can track the target EGR flow rate. In the third mode, the motor is adjusted for boost pressure control, while the VGT and EGR valve are grouped together for EGR control. Unlike the second mode, where the VGT is not adjusted based on feedback from the actual EGR flow rate, here the VGT is adjusted based on feedback from the actual EGR flow rate.

[0071] Figure 9 It shows that based on Figure 3 Method 300 provides an exemplary timeline of engine parameters during operation. In response to target boost power and engine operating conditions, the engine can switch from one operating mode to another. Graph 910 shows boost pressure. Boost pressure increases as shown on the y-axis. Target boost pressure 912 is shown as a dashed line, while actual boost pressure 911 is shown as a solid line. Graph 920 shows the high-pressure EGR flow rate. EGR flow rate increases as shown on the y-axis. Target EGR flow rate 922 is shown as a dashed line, while actual EGR flow rate 921 is shown as a solid line. Graph 930 shows insufficient power. When power is needed from the motor (such as...) Figure 1When assisted by an electric motor 111, insufficient power is positive. When no assistance from the motor is needed, insufficient power is zero or negative. Insufficient power increases as shown on the y-axis. Graph 940 shows the opening of the VGT vanes. The VGT vanes are fully closed at 0% opening, where the restriction on exhaust flow is highest. The VGT vanes are fully open at 100% opening, where the restriction on exhaust flow is lowest. The opening increases as shown on the y-axis. Graph 950 shows the opening of the high-pressure EGR valve. The EGR valve is fully open at 100% opening, where there is no restriction on EGR flow. The EGR valve is fully closed at 0% opening, where no EGR flow passes through the EGR passage. The opening increases as shown on the y-axis. Graph 960 shows the motor (such as...) connecting the compressor and turbine. Figure 1 The electric motor 111 provides auxiliary power. When the motor draws current from the battery and increases the compressor's power output, the motor power is positive. When the motor operates in regenerative mode and charges the battery, the motor power is negative. The motor power output increases as shown on the y-axis. The x-axis of the graph represents time, and time increases from the left to the right of the graph. Graph 970 shows... Figure 3 and Figures 6 to 8 The engine operating mode is shown.

[0072] From T0 to T1, the engine is in idle mode. The target boost pressure is low. Compressor power is insufficient (zero). The engine operates in mode one. The VGT position is adjusted to track the target boost pressure, and the EGR valve is adjusted to track the EGR flow. The VGT vanes are closed. When the target EGR flow is zero, the EGR valve is closed. Motor power is zero.

[0073] At T1, due to aggressive accelerator pedal application, the target boost pressure increases sharply. Therefore, underpower 931 increases sharply from zero. The underpower threshold 932 is updated based on the current engine speed and current boost pressure. Since underpower 931 exceeds threshold 932, the engine operates in third mode, where it tracks the target EGR flow by adjusting VGT position and EGR valve opening, and tracks the target boost pressure by increasing motor power. VGT opening 940 remains low to increase EGR flow. From T1 to T2, the actual boost pressure 911 increases to the target boost pressure 912, and the actual EGR flow 921 increases to the target EGR flow 922. Underpower decreases from T1 to T2. Therefore, motor power output also decreases from T1 to T2.

[0074] At T2, the underpower threshold 932 increases in response to an increase in boost pressure and engine speed (not shown). In response to underpower 931 falling below threshold 932, the engine operates in a second mode. The VGT position is adjusted to the desired efficiency, and the EGR valve is adjusted to track EGR flow. Motor power is positive and adjusted based on VGT opening and target boost pressure. From T2 to T3, actual boost pressure and actual EGR flow continue to increase to track their target values. Motor power output is positive and decreases as underpower decreases.

[0075] At T3, the target boost pressure 912 decreases, and underpower 931 becomes negative. Therefore, the engine operates in mode one. The engine operates in regenerative mode, and motor power 960 becomes negative. The underpower threshold 932 increases with increasing engine speed and boost pressure. As the VGT opening increases and the EGR valve opening decreases, the boost pressure and EGR flow decrease to track their target levels.

[0076] At T4, the target boost pressure 912 increases and the target EGR flow rate 922 also increases. When underpower is below the threshold 932 but above zero, the engine operates in a second mode. Motor power is positive to mitigate underpower. Between T4 and T5, the threshold 932 increases in response to increases in boost pressure and engine speed. Actual boost pressure and actual EGR flow rate approach their target values.

[0077] At T5, underpower is zero. Therefore, the engine operates in mode one. The motor output power is zero. The VGT opening is adjusted to track the target boost pressure, and the EGR valve is adjusted to track the target boost pressure.

[0078] In this way, in engines including electrically assisted VGT, the actuator operates differently to control boost pressure and EGR flow in response to the level of underpower. For example, if the underpower is between zero and a threshold, VGT is adjusted based on the target boost pressure to achieve the desired maximum turbo efficiency. If the underpower is above the threshold, VGT is adjusted based on the target EGR flow. The technical effect of setting VGT to a position with the desired turbo efficiency is that improved fuel / power efficiency can be achieved without affecting the vehicle's driving performance. The technical effect of adjusting VGT based on the target EGR flow is that underpowered EGR can be avoided during aggressive accelerator pedal operation and the vehicle can quickly track sharp increases in target boost pressure. The technical effect of adjusting the threshold based on engine operating conditions is that the operating mode can be switched in response to the current engine operating point to improve driving performance.

[0079] As one embodiment, a method for an engine includes adjusting the position of a turbine coupled to a compressor to achieve a desired turbine efficiency in response to insufficient positive power below a threshold, the compressor supplying boost air to the engine and insufficient power being the difference between a target boost pressure and an actual boost pressure; and adjusting the turbine position based on a target flow rate of exhaust gas recirculation (EGR) returning to the engine in response to insufficient power above the threshold. In a first example, the method includes operating a motor coupled between the compressor and the turbine based on a target boost pressure and the adjusted turbine position. A second example of the method optionally includes the first example and further includes determining the threshold based on engine speed and actual boost pressure. A third example of the method optionally includes adjusting the turbine position based on a target boost pressure and adjusting an EGR valve based on a target EGR flow rate in response to zero or negative insufficient power. A fourth example of the method optionally includes one or more of the first to third examples and further includes determining the actual boost pressure based on the actual turbine position. A fifth example of the method optionally includes one or more of the first to fourth examples and further includes adjusting the EGR valve based on a target EGR flow rate in response to insufficient power above the threshold. A sixth example of the method may optionally include one or more of the first to fifth examples, and further includes adjusting the turbine position and EGR valve based on a target EGR flow rate via a feedback controller. A seventh example of the method may optionally include one or more of the first to sixth examples, and further includes estimating the EGR flow rate and operating a motor coupled between the compressor and turbine based on the estimated EGR flow rate. An eighth example of the method may optionally include one or more of the first to seventh examples, and further includes adjusting the EGR valve position based on the measured EGR flow rate and the target EGR flow rate in response to insufficient positive power exceeding a threshold. A ninth example of the method may optionally include one or more of the first to eighth examples, and further includes wherein the desired turbine efficiency is the maximum turbine efficiency determined based on the blade speed ratio.

[0080] As one embodiment, a method for an engine includes determining underpower based on a target boost pressure and a measured boost pressure from a turbine-driven compressor having variable blade positions and coupled to an engine exhaust system, the compressor delivering compressed air to the engine; adjusting a turbine position based on the target boost pressure in response to underpower in a first range; adjusting the turbine position to achieve a desired turbine efficiency in response to underpower in a second range; and adjusting the turbine position based on a target flow rate of engine exhaust gas recirculation (EGR) returning to the engine in response to underpower in a third range. In a first example of the method, the second range is higher than the first range, and the third range is higher than the second range. A second example of the method optionally includes the first example and further includes adjusting an EGR valve positioned in the EGR flow returning to the engine via a feedback controller based on the target EGR flow rate in response to underpower in the first range. A third example of the method optionally includes one or more of the first and second examples and further includes: operating a motor coupled between the compressor and the turbine to drive the compressor by outputting motor power determined based on the target boost pressure and the adjusted turbine position in response to underpower in the second or third range. A fourth example of the method may optionally include one or more of the first to third examples, and further includes: wherein a first range is equal to or less than zero power insufficiency; a second range is from zero power insufficiency to a positive threshold power insufficiency; and a third range is equal to or greater than a positive threshold power insufficiency. A fifth example of the method may optionally include one or more of the first to fourth examples, and further includes: wherein the threshold is updated based on engine operating conditions. A sixth example of the method may optionally include one or more of the first to fifth examples, and further includes: wherein the threshold increases with increasing engine speed and increasing measured boost pressure.

[0081] As another embodiment, the engine system includes a high-pressure EGR passage coupled between the engine's intake manifold and exhaust manifold; an EGR valve coupled to the high-pressure EGR passage to control the EGR flow rate; a turbocharger including a compressor, a variable geometry turbine, and an electric motor coupled to both the compressor and the turbine; and a controller having computer-readable instructions stored in a non-transitory memory, the computer-readable instructions being configured to: operate the engine in a first mode to adjust the turbine position based on a target boost pressure and adjust the EGR valve position based on a target EGR flow rate; operate the engine in a second mode to adjust the turbine position and the EGR valve position based on the target EGR flow rate; operate the engine in a third mode to adjust the turbine position to achieve a desired turbine efficiency and adjust the EGR valve position based on the target EGR flow rate and the adjusted turbine position; and transition between the first, second, and third modes in response to insufficient power. In a first example of the system, the controller is further configured to transition between the first, second, and third modes by comparing insufficient power with a positive threshold, wherein the threshold is adjusted based on engine operating conditions. A second example of the method may optionally include the first example and further include: when the power deficiency is equal to or less than zero, the engine operates in a first mode; when the power deficiency is between zero and a threshold, the engine operates in a second mode; and when the power deficiency is equal to or greater than the threshold, the engine operates in a third mode.

[0082] It should be noted that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, intermittent-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, or functions shown can be executed in the shown order, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the shown actions, operations, and / or functions can be repeatedly executed depending on the specific strategy used. Furthermore, the actions, operations, and / or functions can be graphically represented by code programmed into a non-transitory memory of a computer-readable storage medium in an engine control system, wherein the actions are executed by combining instructions in a system including various engine hardware components with an electronic controller.

[0083] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many variations are possible. For example, the above-described techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or properties.

[0084] The appended claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may relate to an “a” element or a “first” element or its equivalent. These claims should be understood to include the introduction of one or more such elements, thus neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment to these claims or by setting new claims in this application or related applications. Such claims, whether their scope is broader, narrower, identical, or different from that of the original claims, are also considered to be included within the subject matter of this invention.

[0085] According to the invention, a method includes adjusting the position of a turbine coupled to a compressor to achieve a desired turbine efficiency in response to insufficient power below a threshold, the compressor supplying boosted air to an engine and the insufficient power being the difference between a target boost pressure and an actual boost pressure; and adjusting the turbine position based on a target flow rate of exhaust gas circulating back into the engine in response to insufficient power above a threshold.

[0086] According to an embodiment, the invention is further characterized in that the motor connected between the compressor and the turbine is operated based on the target boost pressure and the adjusted turbine position.

[0087] According to an embodiment, the invention is further characterized in that the threshold is determined based on engine speed and actual boost pressure.

[0088] According to an embodiment, the invention is further characterized in that, in response to zero or insufficient negative power, the turbine position is adjusted based on the target boost pressure, and the exhaust gas recirculation (EGR) valve is adjusted based on the target flow rate of the recirculated exhaust gas.

[0089] According to an embodiment, the invention is further characterized in that the actual boost pressure is determined based on the actual turbine position.

[0090] According to an embodiment, the invention is further characterized in that, in response to insufficient power exceeding a threshold, the exhaust gas recirculation (EGR) valve is adjusted based on the target flow rate of the recirculated exhaust gas.

[0091] According to an embodiment, both the turbine position and the EGR valve are adjusted via a feedback controller based on the target flow rate of the recirculated exhaust gas.

[0092] According to an embodiment, the invention is further characterized by estimating the actual flow rate of exhaust gas recirculated back into the engine, and operating the motor connected between the compressor and the turbine based on the actual EGR flow rate.

[0093] According to an embodiment, the invention is further characterized in that, in response to insufficient positive power below a threshold, the position of the exhaust gas recirculation (EGR) valve is adjusted based on the measured EGR flow and the target EGR flow.

[0094] According to an embodiment, the desired turbine efficiency is the maximum turbine efficiency determined based on the blade speed ratio.

[0095] According to the present invention, a method includes determining underpower based on a target boost pressure and a measured boost pressure from a turbine-driven compressor having variable blade positions and coupled to an engine exhaust system, the compressor delivering compressed air to the engine; adjusting the turbine position based on the target boost pressure in response to underpower in a first range; adjusting the turbine position to achieve a desired turbine efficiency in response to underpower in a second range; and adjusting the turbine position based on a target flow rate of engine exhaust gas recirculation (EGR) returning to the engine in response to underpower in a third range.

[0096] According to an embodiment, the second range is higher than the first range, and the third range is higher than the second range.

[0097] According to an embodiment, the invention is further characterized in that, in response to insufficient power within a first range, the EGR valve positioned in the EGR flow returning to the engine is adjusted via a feedback controller based on the target EGR flow.

[0098] According to an embodiment, the invention is further characterized in that, in response to insufficient power in a second or third range, a motor connected between the compressor and the turbine is operated, the motor being operated by motor power to drive the compressor based on a target boost pressure and an adjusted turbine position.

[0099] According to the embodiment, the first range is equal to or less than zero power insufficiency; the second range is from zero power insufficiency to positive threshold power insufficiency; and the third range is equal to or greater than positive threshold power insufficiency.

[0100] According to the embodiment, the threshold is updated based on the engine operating condition.

[0101] According to an embodiment, the threshold increases with increasing engine speed and increasing measured boost pressure.

[0102] According to the present invention, an engine system is provided having a high-pressure EGR passage connected between an intake manifold and an exhaust manifold of the engine; an EGR valve controlling the EGR flow through the EGR passage; a turbocharger including a compressor, a variable geometry turbine, and an electric motor connected to both the compressor and the turbine; and a controller having computer-readable instructions stored in a non-transitory memory, the computer-readable instructions being configured to: operate the engine in a first mode to adjust the turbine position based on a target boost pressure and adjust the EGR valve position based on a target EGR flow; operate the engine in a second mode to adjust the turbine position and the EGR valve position based on the target EGR flow; operate the engine in a third mode to adjust the turbine position to obtain a desired turbine efficiency and adjust the EGR valve position based on the target EGR flow and the adjusted turbine position; and switch between the first mode, the second mode, and the third mode in response to insufficient power based on the difference between the target boost pressure and the actual boost pressure.

[0103] According to an embodiment, the controller is also configured to switch between a first mode, a second mode, and a third mode by comparing insufficient power with a positive threshold, wherein the threshold is adjusted based on engine operating conditions.

[0104] According to an embodiment, when the power deficiency is equal to or less than zero, the engine operates in a first mode; when the power deficiency is between zero and a threshold, the engine operates in a second mode; and when the power deficiency is equal to or greater than the threshold, the engine operates in a third mode.

Claims

1. A method comprising: The underpower threshold is estimated based on the estimated boost pressure and measured engine speed. In response to insufficient power below the insufficient power threshold, the position of the turbine coupled to the compressor is adjusted based on the desired turbine efficiency, the compressor supplying boost air to the engine, and the insufficient power is the difference between the target boost pressure and the estimated boost pressure; as well as In response to the insufficient power exceeding the insufficient power threshold, the position of the turbine is adjusted based on the target flow rate of exhaust gas recirculated back into the engine.

2. The method of claim 1, further comprising operating a motor coupled between the compressor and the turbine based on the target boost pressure and the adjusted turbine position.

3. The method of claim 1, further comprising adjusting the turbine position based on the target boost pressure in response to zero or insufficient negative power, and adjusting the exhaust gas recirculation (EGR) valve based on the target flow rate of the recirculated exhaust gas.

4. The method of claim 1, further comprising determining the estimated boost pressure based on the actual turbine position.

5. The method of claim 1, further comprising: In response to the insufficient power exceeding the insufficient power threshold, the exhaust gas recirculation (EGR) valve is adjusted based on the target flow rate of the recirculated exhaust gas.

6. The method of claim 5, wherein both the turbine position and the exhaust gas recirculation (EGR) valve are adjusted via a feedback controller based on the target flow rate of the recirculated exhaust gas.

7. The method of claim 6, further comprising: Estimate the actual exhaust flow rate recirculated back into the engine, and operate the motor connected between the compressor and the turbine based on the actual exhaust flow rate recirculated back into the engine.

8. The method of claim 1, further comprising: In response to insufficient positive power below the insufficient power threshold, the exhaust gas recirculation (EGR) valve position is adjusted based on the measured EGR flow and the target flow.

9. The method of claim 1, wherein the desired turbine efficiency is the maximum turbine efficiency determined based on the blade speed ratio.

10. An engine system comprising: The high-pressure EGR passage connects the engine's intake manifold and exhaust manifold. EGR valve, which is used to control the EGR flow rate through the EGR channel; A turbocharger includes a compressor, a variable geometry turbine, and an electric motor connected to both the compressor and the turbine; The controller has computer-readable instructions stored in a non-transitory memory, the computer-readable instructions being configured to: The engine is operated in a first mode to adjust the position of the turbine based on a target boost pressure and the position of the EGR valve based on a target EGR flow rate; The engine is operated in a second mode to adjust the turbine position and the EGR valve position based on the target EGR flow rate; The engine is operated in a third mode to adjust the turbine position to achieve the desired turbine efficiency and to adjust the EGR valve position based on the target EGR flow and the adjusted turbine position. The underpower threshold is estimated based on the actual boost pressure and measured engine speed; and In response to a comparison of insufficient power with a power deficiency threshold, the system switches between a first mode, a second mode, and a third mode, wherein the power deficiency is based on the difference between the target boost pressure and the actual boost pressure.

11. The engine system of claim 10, wherein the engine operates in the first mode when the power deficiency is equal to or less than zero, the engine operates in the second mode when the power deficiency is between zero and the power deficiency threshold, and the engine operates in the third mode when the power deficiency is equal to or greater than the power deficiency threshold.

12. The engine system of claim 10, further comprising adjusting an EGR valve positioned in the EGR flow returning to the engine based on the target EGR flow via a feedback controller.

13. The engine system of claim 10, further comprising switching between the first mode, the second mode, and the third mode in response to engine operating conditions.

Images