Method and system for active housing handling control

Abstract

The present application relates to methods and systems for active housing treatment control. A method and system are provided for adjusting an active housing treatment device of a compressor in response to predicted engine conditions. In one example, the controller actuates a sleeve of a variable geometry compressor housing to a position selected based on each of a compressor pressure ratio and a mass flow rate through the compressor, as well as driver behavior and predicted road conditions; and adjusts each of an EGR actuator and a boost actuator based on the selected position to maintain the compressor pressure ratio during actuation.

Description

Technical Field

[0001] This description generally relates to methods and systems for controlling the operation of a variable geometry compressor having an active casing treatment (ACT). Background Art

[0002] An engine may use a turbocharger to increase engine torque / power output density. The turbocharger may include a compressor and a turbine connected by a drive shaft, where the turbine is coupled to the engine's exhaust manifold and the compressor is coupled to the engine's intake manifold. The exhaust-driven turbine supplies energy to the compressor to increase the flow of compressed air into the engine. The use of a compressor allows a smaller displacement engine to provide as much power as a larger displacement engine, but with additional fuel economy benefits.

[0003] However, compressors are prone to surge and choke. For example, when an operator releases the accelerator pedal, the air flow decreases, causing a reduction in the forward flow through the compressor at a high pressure ratio (PR), which may cause the compressor to surge. In another example, surge may be caused in part by a high level of cooled exhaust gas recirculation (EGR), which increases the compressor pressure while reducing the mass flow through the compressor. Compressor surge can cause NVH problems, such as undesirable noise from the engine intake system.

[0004] Compressor choke may be encountered at high flow rates when compressor speed increases and the flow rate increases decrementally. When the flow rate at any point in the compressor reaches a choke condition, no further increase in the flow rate is possible. This condition represents the maximum compressor volume flow rate as a function of the pressure ratio. Choke occurs when, for a given compressor speed, the mass flow rate of air through the compressor cannot be increased. The flow rate into the compressor may be limited by the compressor inlet size, and when the flow rate at the inlet reaches the speed of sound, the flow rate may not increase further. As an example, choke may occur when an operator steps on the pedal from a part load or idle condition to a high load condition (such as when going uphill with a load).

[0005] A variety of methods have been developed to operate a compressor outside of both the surge boundary and the choke boundary by reducing the air flow rate before surge occurs and increasing the air flow rate before choke occurs. One example method includes using a passive casing treatment device for the compressor. In one example, the passive casing treatment device may include immovable slots and / or orifices that modify the air flow through the compressor. During low air mass flow conditions, the slots of the passive casing treatment device may provide a path for recirculating a portion of the pressurized air back to the compressor inlet. The recirculated air flowing through the compressor may enable the compressor to operate at a lower air mass flow rate before surge occurs. During high air mass flow conditions, the slots and / or orifices of the passive casing treatment device may provide a path for short-circuiting the air flow through the compressor, such that the compressor can operate at a higher air mass flow rate before choke occurs. It has been recognized that one drawback of passive casing treatment systems is that the effective location of the passive recirculation slots for preventing surge is different from the effective location of the passive recirculation slots for preventing choke.

[0006] Another example method includes using an active casing treatment (ACT) device for the compressor, such as that shown by Sun et al. in US8,517,664. In this, a turbocharger includes an active casing treatment device, an impeller, a casing, and a diffuser. A controller adjusts a casing sleeve in response to a mass flow condition relative to a threshold or based on a pressure differential in the engine system such that slots in the casing sleeve are aligned with either a surge slot or a choke slot. In response to the slot alignment, air selectively flows between the impeller and the compressor inlet.

[0007] However, the inventors herein have recognized potential problems with such methods. As an example, adjusting the active casing treatment (ACT) device in response to a current engine operating condition is a reactive control method that may sacrifice efficiency and performance by not adjusting compressor operation until the compressor is already in or near a surge or choke condition. In another example, this type of reactive control method may result in high-frequency actuation of the casing sleeve to expose (e.g., open) a choke slot or a surge slot, which can cause flow pulsations, further reducing compressor efficiency and degrading performance. SUMMARY OF THE INVENTION

[0008] In one example, the above problem can be solved by a method for a supercharged engine, the method comprising: actuating a sleeve of a variable geometry compressor housing to a selected position based on each of a compressor pressure ratio and a mass flow through the compressor; and adjusting each of an EGR actuator and a supercharging actuator based on the selected position to maintain the compressor pressure ratio during actuation. In this way, disturbances associated with actuation of the active housing treatment device can be compensated for such that a constant pressure flow during ACT actuation can be maintained, allowing compressor operation over a wider range of operating conditions.

[0009] As an example, a supercharged engine can be configured with a turbocharger having a variable geometry compressor (VGC) and an exhaust gas turbine. The VGC includes an impeller surrounded by a housing and an active housing treatment device. The housing includes a compressor inlet, an intake passage, a recirculation passage, a surge port, a choke port, and an actuatable sleeve having a bleed port. In response to compressor operation within a choke margin (i.e., a threshold distance from a compressor choke limit), the engine controller can actuate the housing sleeve to a choke slot, causing air to flow from the compressor inlet to the impeller via the choke port of the housing. In response to actuating the sleeve to the choke slot, the high-pressure EGR valve opening can be increased to increase the high-pressure EGR flow rate in order to maintain the air pressure flow across the compressor and the pressure ratio across the compressor regardless of the opening of the choke port. Additionally, a supercharging actuator such as a wastegate valve position or a vane angle of a variable geometry turbine can be adjusted to compensate for any disturbances caused by actuating the sleeve to the choke slot. In contrast, in response to compressor operation within a surge margin (i.e., a threshold distance from a compressor surge limit), the engine controller can actuate the housing sleeve to a surge slot, causing air to flow from the impeller to the compressor inlet via the surge port of the housing. In response to actuating the sleeve to the surge slot, the high-pressure EGR valve opening can be decreased to decrease the high-pressure EGR flow rate in order to maintain the air flow across the compressor and the pressure ratio across the compressor regardless of the opening of the surge port. Additionally, the wastegate valve position or a variable geometry turbine (VGT) vane angle can be adjusted to compensate for any disturbances caused by actuating the sleeve to the surge slot.

[0010] Additionally, the controller can dynamically (e.g., in real time) perform each of the following based on driver behavior (such as based on the frequency and magnitude of driver pedal application) and driving conditions (such as road grade and altitude): adjust the choke margin to the choke limit and adjust the surge margin to the choke limit. If the energy demand from driver pedal application is high (such as can occur when the driver tends to drive aggressively), then at least the surge margin can be increased such that the housing sleeve engages the surge slot earlier and is released from the surge slot later in the driving cycle.

[0011] In this way, driver behavior can be filtered to allow for smooth engagement / disengagement profiles of the ACT. Additionally, the ACT actuation frequency is reduced. By limiting ACT actuation to a threshold actuation frequency, flow pulsations and efficiency losses from ACT actuation can be reduced. By adjusting the EGR flow and turbocharger actuator operation based on ACT actuation, any flow pulsations or disturbances caused by actuation can be better mitigated, thereby improving overall compressor performance. By adjusting the choke margin and surge margin based on driver behavior and predicted driving conditions, greater surge and choke protection can be provided. Overall, for both choke and surge conditions, compressor operation can be better optimized and the operating range of the turbocharger can be extended.

[0012] It should be understood that the above summary is provided to introduce in a simplified form a selection of concepts that are further described in the detailed description. This does not mean identifying the key or essential features of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Also, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Shows an example embodiment of a vehicle system including a turbocharged engine.

[0014] Figure 2 Shows Figure 1 a diagram of an example embodiment of one cylinder of a turbocharged engine.

[0015] Figure 3 Shows a cross-sectional view of an example embodiment of a Figure 1 and Figure 2 turbocharger having a compressor and a turbine.

[0016] Figure 4A and Figure 4B respectively show the actuation of the sleeve of the active casing treatment device to the surge slot and the choke slot.

[0017] Figure 5 Shows a high-level flowchart of a method for predictive control of a turbocharger having an active casing treatment device.

[0018] Figure 6 Shows a high-level flowchart of active sleeve casing actuation in response to predicted choke and / or surge conditions.

[0019] Figure 7 Shows a block diagram of active casing treatment control for a variable geometry compressor in a turbocharged engine.

[0020] Figure 8Shows an example compressor pressure ratio map including a surge limit and a choke limit.

[0021] Figure 9 Shows a predictive example of turbocharger operation with ACT sleeve adjustment to mitigate surge and choke.

[0022] Figure 10 Shows an example barrier function that can be used to modify the ACT operation frequency. Detailed Description

[0023] The following description relates to systems and methods for controlling the operation of an active housing treatment device for a turbocharger compressor to reduce the occurrence of surge and choke. Figure 1 Shows a non-limiting example embodiment of a hybrid vehicle system including a turbocharged engine. Figure 2 Shows Figure 1 A cross-sectional view of a cylinder (e.g., "combustion chamber") of the engine. In Figure 3 A cross-sectional view more detailedly shows an example turbocharger such that components affecting the pneumatic flow through the turbocharger including the active housing treatment device can be inspected. Figure 4A And Figure 4B Shows example positions to which the sleeve of the active housing treatment device can be actuated in response to different engine operating conditions. The engine controller can be configured to execute control programs such as Figures 6 - 7 An example program of Figure 8 To vary the position of the sleeve of the active housing treatment device based on engine operation relative to the compressor choke limit and surge limit, as inferred from a compressor map (such as Figure 9 The map of

[0024] Now turning to Figure 1, an exemplary embodiment of the vehicle system 100 is schematically (not to scale) shown. In one example, the vehicle system 100 can be configured as a road motor vehicle. However, it should be understood that in other examples, the vehicle system 100 can be configured as an off-road vehicle. In some examples, the vehicle system 100 can be a hybrid vehicle having multiple torque sources available for one or more wheels 76. In other examples, the vehicle system 100 is a conventional vehicle having only an engine or an electric vehicle having only a motor(s). In the illustrated example, the vehicle system 100 includes an engine 10 and a motor 72. The motor 72 can be a motor or a motor / generator (M / G). When one or more clutches 73 are engaged, the crankshaft 40 of the engine 10 and the motor 72 are connected to the wheels 76 via a transmission 74. In the depicted example, a first clutch 73 is provided between the crankshaft 40 and the motor 72, and a second clutch 73 is provided between the motor 72 and the transmission 74. The controller 12 discussed herein can send signals to the actuators of each clutch 73 to engage or disengage the clutches so as to connect or disconnect the crankshaft 40 from the motor 72 and the components connected thereto, and / or connect or disconnect the motor 72 from the transmission 74 and the components connected thereto. 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 as a parallel, series, or series-parallel hybrid vehicle.

[0025] The motor 72 receives electrical power from the traction battery 75 to provide torque to the wheels 76. The motor 72 can also operate as a generator to provide electrical power to the charging battery 75, for example, during a braking operation. In other examples, in the case where the vehicle system 100 is a conventional vehicle having only an engine, the traction battery 75 can be a starting-lighting-ignition (e.g., SLI) battery that supplies electrical energy to the vehicle system 100.

[0026] In the depicted embodiment, the engine 10 is a supercharged engine that includes a turbocharger 13. The turbocharger 13 includes a turbine 116 positioned in an exhaust passage 35, and the turbine 116 is coupled to a compressor 110 positioned in an intake passage 42. The turbine 116 and the compressor 110 can be coupled via a shaft 19. The compressor 110 can be positioned upstream of a charge air cooler 18 (also referred to herein as a CAC) and an intake throttle 20. The turbine 116 can be driven (e.g., rotated) by expanding the exhaust from the engine 10, and the rotational energy of the turbine 116 can be transmitted via the shaft 19 to rotate the compressor 110.

[0027] In one example, the compressor 110 is a variable geometry compressor (VGC) having vanes that move according to a desired vane angle so as to direct the intake air flow into the compressor in different modes. Further, as referenced Figure 3 ,Figure 4A and Figure 4B and Figure 5 In detail, the compressor 110 may include an active casing treatment device (ACT) having a sleeve that can be actuated between different positions to reduce or increase the flow into the compressor wheel (or impeller). For example, in response to an indication of surge (actual or predicted), the sleeve can be actuated by the engine controller to a surge slot to increase the flow from the compressor wheel out to the compressor inlet. In another example, in response to an indication of choke (actual or predicted), the sleeve can be actuated by the engine controller to a choke slot to increase the flow from the compressor inlet to the compressor wheel.

[0028] In some examples, the turbine 116 may be a variable geometry turbine having vanes with adjustable angles so as to direct the exhaust gas flow through the turbine blades in different modes, thereby varying the turbine speed and the boost pressure provided by the turbocharger 13.

[0029] The engine 10 receives air along the intake passage 42 via an air box 44 including an air cleaner 112. 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, through the CAC 18 for cooling, and through the throttle 20 before entering the intake manifold 22 (where the compressed air enters the engine 10). In other words, the compressor 110 is coupled to the intake throttle 20 via the charge air cooler 18, and the intake throttle 20 is coupled upstream of the intake manifold 22. For example, the charge air cooler can be an air - air heat exchanger or a water - air heat exchanger. In Figure 1 the illustrated embodiment, the pressure of the air charge in the intake manifold is sensed by a manifold air pressure (MAP) sensor 124.

[0030] It should be understood that other combinations and configurations of the supercharging devices may be possible. In one embodiment, the turbocharger can be a twin scroll device. In another embodiment, the turbocharger 13 can be a variable geometry turbocharger (VGT), where the turbo geometry actively changes according to engine operating conditions such as by changing the vane blade angles or nozzle angles. In yet another embodiment, the engine system 100 can include a supercharger, where the compressor 110 can be driven at least in part by an electric motor and / or the engine 10, and the engine system may not include the turbine 116. In additional examples, multiple supercharging devices can be serially staged, such as when both a supercharger and a turbocharger are coupled to the intake passage.

[0031] The compressor 110 may include a recirculation passage 80 across the compressor. The depicted example shows a compressor recirculation valve (CRV) 82 coupled at both ends of the recirculation passage 80, where actuation of the CRV 82 adjusts the flow 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 the charge air cooler, to the compressor inlet, or a compressor bypass for dissipating the compressed air to the atmosphere (not shown). The CRV 82 may be a continuously variable valve, where the position of the valve 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 boosted engine operation to provide some surge margin. Herein, the partially open position may be the default valve position. Increasing the opening of the compressor recirculation valve may include actuating (or energizing) the solenoid of the valve. Further discussion of example CRV operation will be discussed herein.

[0032] One or more sensors may be coupled to the inlet of the compressor 110 for determining the composition and condition of the air charge entering the compressor. For example, an intake air temperature (IAT) sensor 55 may be coupled to the intake passage 42, adjacent to the inlet of the compressor 110, for estimating the compressor inlet temperature. As another example, a pressure sensor 56 may be coupled to the inlet of the compressor for estimating the pressure of the air charge entering the compressor. In another example, a mass air flow (MAF) sensor 57 may also be coupled to the inlet of the compressor for estimating 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. The sensors may estimate the condition of the intake air received from the intake passage at the compressor inlet and the air charge recirculated from upstream of the CAC. A throttle inlet pressure (TIP) sensor 58 or other suitable sensor may be coupled downstream of the compressor 110 and upstream of the throttle 20 for measuring the pressure at a location downstream of the compressor 110 and upstream of the throttle 20. In this way, the compressor outlet pressure may be determined.

[0033] The intake manifold 22 is coupled to a series of combustion chambers 30 via a series of intake valves (refer to Figure 2 for further description). The combustion chambers are also coupled via a series of exhaust valves (refer to Figure 2is further described) is coupled to the exhaust manifold 36. In the depicted embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold 36 may include multiple exhaust manifold sections. A configuration having multiple exhaust manifold sections may enable the effluents from different combustion chambers to be directed to different locations in the engine system 10.

[0034] The combustion chamber 30 may be supplied with one or more fuels such as gasoline, alcohol fuel blends, diesel, biodiesel, compressed natural gas, etc. by a fuel system (refer to Figure 2 is further described). The fuel may be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Direct injection includes injecting the fuel directly into the combustion chamber, and port injection delivers the fuel spray into the intake port 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. In the combustion chamber, combustion may be initiated via spark ignition and / or compression ignition.

[0035] As Figure 1 shown, the exhaust from one or more sections of the exhaust manifold 36 is directed to the turbine 116 to drive the turbine. When a reduced turbine torque is desired, instead, some of the exhaust may be directed through the wastegate 90, bypassing the turbine 116. The wastegate valve 92 coupled to the wastegate 90 may be actuated to open to relieve at least some of the exhaust pressure from upstream of the turbine 116 via the wastegate 90 to a location downstream of the turbine. By reducing the exhaust pressure upstream of the turbine 116, the turbine speed may be reduced. In one embodiment, the wastegate valve 92 may be vacuum actuated, i.e., the wastegate valve 92 may be actuated via the application of vacuum. The combined flow from the turbine 116 and the wastegate 90 then flows through an emissions control device (refer to Figure 2 is further described) before all or part of the treated exhaust may be released to the atmosphere via the exhaust passage 35.

[0036] During a condition where there is an instantaneous increase in driver torque demand, such as during pedal depression, when transitioning from non-boosted engine operation to boosted engine operation, the throttle 20 opening may be increased to increase the air flow to the engine. The opening of the wastegate valve 92 may be reduced to increase the flow of exhaust through the turbine 116, which increases the turbine speed. In one example, the wastegate valve 92 may be fully closed during boosted engine operation such that the increased speed of the turbine may drive the compressor 110.

[0037] During conditions where there is a reduced driver torque demand, such as during pedal release, when transitioning from supercharged engine operation to non-supercharged or reduced supercharged engine operation, the throttle 20 opening may be reduced. In one example, the throttle 20 opening may be closed. In response to compressor operation moving towards the surge limit in response to pedal release, the CRV 82 may be opened so that the higher speed of the turbine 116 does not choke the compressor 110 and cause compressor surge. The wastegate valve 92 is also opened to increase the flow of exhaust bypassing the turbine 116 and reduce turbine speed. This allows for the release of overboost pressure substantially immediately. Reference Figure 9 An example turbocharger operation is shown.

[0038] During conditions where the engine 10 is idling and the vehicle system 100 is stopped, the intake throttle may be opened just enough to keep the engine running. In other examples, such as where the engine includes an idle control valve, when the idle control valve is open, the intake throttle may be fully closed so that sufficient air is delivered to the engine to maintain engine idle. Thus, during engine idle conditions, the compressor 110 may not be rotating.

[0039] The engine 10 may also include one or more exhaust gas recirculation (EGR) passages for recirculating a portion of the exhaust from the exhaust manifold to the intake manifold. By recirculating some of the exhaust, 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, the exhaust may be recirculated from the exhaust manifold 36, upstream of the turbine 116, to the intake manifold 22, downstream of the compressor 110 and throttle 20 via the EGR passage 84. This configuration may be referred to as a high pressure (HP) EGR system. The EGR passage 84 may include an EGR valve 86 for controlling the HP EGR flow and an EGR cooler for cooling the exhaust before delivery to the intake manifold. In additional examples, the exhaust may be recirculated from the exhaust passage 35, downstream of the turbine 116, to the intake passage 22, upstream of the compressor 110, to provide low pressure (LP) EGR. Reference Figure 1 An example of LP EGR is shown. As detailed in Figure 6 and Figure 7 After ACT sleeve actuation, one or more of the EGR valve and additional boost actuators (such as the wastegate valve 92) may be actuated to reduce the airflow disturbance incurred by compressor ACT sleeve actuation.

[0040] The engine system 100 may further include a control system 14 that includes a controller 12. The controller 12 is shown receiving information from a plurality of sensors 16 (various examples of the plurality of sensors 16 are described herein), and sending control signals to a plurality of actuators 81 (various examples of the plurality of actuators 81 are described herein). As an example, the sensors 16 may include a MAP sensor 124, an exhaust gas temperature sensor 128, an exhaust gas 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 in the engine system 10. In one example, a compressor speed sensor 54 may be coupled to the compressor 110 to determine the rotational speed of the compressor. According to a non-limiting embodiment, the compressor speed sensor 54 may be a passive eddy current sensor. In one example, the compressor speed sensor 54 may be a passive eddy current sensor. The actuators 81 may include, for example, a throttle 20, a compressor recirculation valve 82, an exhaust gas valve 92, a direct fuel injector 66, and an intake port fuel injector 67.

[0041] The control system 14 may be coupled to a navigation system 154 and a wireless communication device 152. The navigation system 154 determines the position of the vehicle system 100 when turned on and at any other time. The position of the vehicle system 100 as estimated by the navigation system 154 (e.g., the GPS coordinates of the vehicle) may be stored at the control system 14 for use during a driving cycle. The navigation system may be connected to an external server and / or network cloud 160 via wireless communication 150. The navigation system 154 may determine the current position of the vehicle system 100 and obtain traffic and road condition data from the network cloud 160 for use in controlling engine operation. Additionally, based on a destination selected by the operator, the navigation system 154 may provide various route options and then provide step-by-step instructions for navigating the vehicle system from the current position (e.g., the starting location) to the selected destination.

[0042] The controller 12 can also receive input data from one or more of the network cloud 160, vehicle-to-vehicle technology (V2V) 170, and vehicle-to-infrastructure technology (V2I) via the wireless communication 150 through the wireless communication device 152. V2V 180 can allow the control system 14 to communicate with other similarly equipped vehicles including the wireless communication device 172 to collect information about traffic and road conditions from the infrastructure including the wireless communication device 182. In one example, V2V can indicate the vehicle speed along the intended route, such as whether other vehicles may stop ahead, or whether there is stop-and-go traffic along the current route relative to an alternative route. In another example, V2I can indicate an upcoming red traffic light or traffic accident along the 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).

[0043] Various types of data including but not limited to grade 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 the navigation system 154 input, the controller 12 can identify the driving mode. Specifically, the controller 12 can "learn" that the vehicle operator commutes the same route every weekday morning. The controller can store data about the route, which includes road grade information and / or expected traffic conditions, and together with the learned driver model can actively control the compressor housing processing device to avoid predicted chokes or predicted surge conditions. The learned driver model can be generated by storing data related to the habits of the vehicle operator. For example, during several weekday commutes, the controller can learn that during the morning commute, the driver exhibits relatively moderate driving habits (e.g., as indicated by the gradual and infrequent actuation of the accelerator pedal and the brake pedal, resulting in gradual acceleration and occasional braking). This type of driving behavior (referred to herein as "moderate driver mode") can result in low energy density actuation of the accelerator pedal.

[0044] As another example, the controller may learn that during a night commute, the driver exhibits more aggressive driving habits (e.g., as indicated by more sudden and frequent actuation of the accelerator pedal and brake pedal), which is referred to herein as the "aggressive driver mode" for illustrative purposes. The aggressive driver mode may result in high energy density actuation of the accelerator pedal. While these examples are intended to illustrate the value of establishing a driver model, they are in no way limiting, and additional modes may still be modeled, learned, and characterized. It should be understood that any suitable number of driver modes may be included in the learned driver model to characterize different driving habits. When the vehicle controller identifies high energy density actuation, which implies potential aggressive driving behavior, the controller may determine that the compressor is more likely to enter surge. Accordingly, in response to the identification of the aggressive driver mode, the controller may increase the surge margin to the surge limit (i.e., the threshold margin from the surge limit at which a surge mitigation action is initiated). Thus, the sleeve of the active casing treatment device of the compressor may be actuated to the surge slot earlier and held in the surge slot for a longer time compared to when it would respond to a moderate driver mode, thereby providing greater surge protection for the compressor.

[0045] In this manner, the vehicle controller 12 may communicate with the vehicle controllers of other vehicles via their respective navigation systems 154, via the wireless communication device 152, and / or via other forms of vehicle-to-vehicle technology (V2V).

[0046] The controller 12 may employ the actuator 81 in response to the processed input data received from various sensors based on instructions stored in the controller's memory or code programmed therein corresponding to one or more programs, such as Figures 6 - 7 the example program). As an example, the controller 12 may determine whether the operating condition of the compressor 110 is within the surge threshold. In one example, to determine the compressor operating condition relative to the surge threshold, the pressure ratio across the compressor and the compressor speed may be determined. In some examples, the pressure ratio of the compressor 110 may be determined by dividing the absolute pressure sensed at the compressor outlet by the absolute pressure sensed at the compressor inlet. In the depicted example, the output of the compressor inlet pressure sensor 56 may be used to determine the pressure upstream of the compressor, and the output of the throttle inlet pressure sensor 58 may be used to determine the pressure downstream of the compressor. Additionally, the controller may use the output of the compressor speed sensor 54 to determine the rotational speed of the compressor 110. In response to the pressure ratio of the compressor 110 being within the threshold margin of the defined surge limit of the compressor, the controller 12 may send a signal to actuate the sleeve of the active casing treatment device of the compressor 110 to increase the opening of the surge slot to provide a path for recirculating a portion of the pressurized air back to the compressor inlet.

[0047] Now turning to Figure 2, showing an exemplary embodiment 200 of a combustion chamber (e.g., a cylinder) of an internal combustion engine (such as the engine 10 of Figure 1 previously introduced in ). Components previously introduced in may be numbered similarly. The engine 10 may receive control parameters from a control system including a controller 12 and receive input from a vehicle operator 230 via an input device 232. In this example, the input device 232 includes an accelerator pedal and a pedal position sensor 234 for generating a proportional pedal position signal PP. A cylinder (also referred to herein as a "combustion chamber") 30 of the engine 10 may include a combustion chamber wall 236 with a piston 238 positioned therein. The piston 238 may be coupled to a crankshaft 40 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of the vehicle system via a transmission system. Figure 1 The cylinder 30 may receive intake air via an intake passage 42, a suction passage 43, and a suction manifold 22. In addition to the cylinder 30, the suction manifold 22 may communicate with other cylinders of the engine 10. In some embodiments, one or more of the intake passages may include a boosting device, such as a turbocharger or a supercharger. For example,

[0048] the engine 10 shown configured with a turbocharger 13 includes a compressor 110 disposed between the intake passage 42 and the suction passage 43, and an exhaust turbine 116 disposed between the exhaust manifold 36 and the exhaust passage 35. The compressor 110 may be at least partially powered by the exhaust turbine 116 via a shaft 19, where the boosting device is configured as a turbocharger. As previously described, in an example where the engine 10 is provided with a supercharger, the exhaust turbine 116 may optionally be omitted, where the compressor 110 may be powered by a mechanical input from a motor or the engine 10. The throttle 20 may include a throttle plate 264 and may be disposed along the intake passage of the engine for varying the flow rate and / or pressure of the intake air provided to the engine cylinders. For example, the throttle 20 may be disposed downstream of the compressor 110, or alternatively may be disposed upstream of the compressor 110. Figure 2 The exhaust manifold 36 may receive exhaust from other cylinders of the engine 10 in addition to the cylinder 30. An exhaust sensor 228 is shown coupled to the exhaust manifold 36 upstream of an emissions control device 278, but it should be understood that it may be located at other positions in the exhaust system. The exhaust sensor 228 may be selected from various suitable sensors for providing an indication of the exhaust air-fuel ratio, e.g., such as a linear oxygen sensor or UEGO (universal or wide-range exhaust oxygen), a two-state oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor. The emissions control device 278 may be a three-way catalyst (TWC), a NOx trap, various other emissions control devices, or a combination thereof.

[0049] The exhaust manifold 36 may receive exhaust from other cylinders of the engine 10 in addition to the cylinder 30. An exhaust sensor 228 is shown coupled to the exhaust manifold 36 upstream of an emissions control device 278, but it should be understood that it may be located at other positions in the exhaust system. The exhaust sensor 228 may be selected from various suitable sensors for providing an indication of the exhaust air-fuel ratio, e.g., such as a linear oxygen sensor or UEGO (universal or wide-range exhaust oxygen), a two-state oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor. The emissions control device 278 may be a three-way catalyst (TWC), a NOx trap, various other emissions control devices, or a combination thereof.

[0050] Each cylinder of the engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 30 is shown including at least one poppet intake valve 250 and at least one poppet exhaust valve 256 in an upper region of the cylinder 30. In some embodiments, each cylinder of the engine 10 (including cylinder 30) may include at least two intake lift valves and at least two exhaust lift valves in an upper region of the cylinder.

[0051] The intake valve 250 may be controlled by the controller 12 via cam actuation of a cam actuation system 251. Similarly, the exhaust valve 256 may be controlled by the controller 12 via a cam actuation system 253. Each of the cam actuation system 251 and the cam actuation system 253 may include one or more cams and may utilize one or more of a cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) system operable by the controller 12 to vary valve operation. Whether electronically actuated or cam actuated, the opening and closing timing of the exhaust and intake valves may be adjusted as specified for desired combustion and emission control performance. The operation of the intake valve 250 and the exhaust valve 256 may be determined by a valve position sensor (not shown) and / or camshaft position sensors 255 and 257, respectively. In alternative embodiments, the intake and / or exhaust valves may 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 may be actuated to adjust the timing of the intake and exhaust valves to a timing that provides a reduced intake valve and exhaust valve positive overlap. That is, the intake and exhaust valves will be open for a shorter duration and will be moved from being open simultaneously during 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.

[0052] In some embodiments, each cylinder of the engine 10 may include a spark plug 292 for initiating combustion. The ignition system 290 may provide an ignition spark to the cylinder 30 via the spark plug 292 in a selected operating mode in response to a spark advance signal SA from the controller 12. In other embodiments, a compression ignition engine may use a glow plug instead of the spark plug 292.

[0053] In some embodiments, each cylinder of the engine 10 may be configured with one or more injectors for delivering fuel to the cylinder 30. As a non-limiting example, the cylinder 30 is shown including two fuel injectors 66 and fuel injector 67. The fuel injectors 66 and 67 may be configured to deliver fuel received from the fuel system 288 via a high-pressure fuel pump and a fuel rail. Alternatively, the fuel may be delivered by a single-stage fuel pump at a lower pressure, in which case the timing of direct fuel injection during the compression stroke may be more restricted compared to if a high-pressure fuel system were used. Additionally, the fuel tank may have a pressure transducer that provides a signal to the controller 12.

[0054] Fuel injector 66 is shown as being directly coupled to the cylinder 30 for directly injecting fuel therein in proportion to the pulse width of a signal FPW-1 received from the controller 12 via the electronic driver 268. In this manner, fuel injector 66 provides so-called direct injection of fuel (hereinafter referred to as "DI") into the combustion cylinder 30. Although Figure 2 injector 66 is shown positioned on one side of the cylinder 30, it may alternatively be located on top of the piston, such as in a position close to the spark plug 292. Due to the lower volatility of some alcohol-based fuels, such a position may improve mixing and combustion when operating the engine with an alcohol-based fuel. Alternatively, the injector may be located on top and close to the intake valve to improve mixing.

[0055] In a configuration providing so-called port fuel injection (hereinafter referred to as "PFI") of fuel into the intake port upstream of the cylinder 30, fuel injector 67 is shown disposed in the intake manifold 22 rather than in the cylinder 30. Fuel injector 67 may inject fuel received from the fuel system 288 in proportion to the pulse width of a signal FPW-2 received from the controller 12 via the electronic driver 271. It should be noted that a single electronic driver 268 or electronic driver 271 may be used for both fuel injection systems, or as depicted, multiple drivers may be used, such as electronic driver 268 for fuel injector 66 and electronic driver 271 for fuel injector 67.

[0056] During a single cylinder cycle, fuel may be delivered to the cylinder by the two injectors. For example, each injector may deliver a portion of the total fuel injection that is burned in the cylinder 30. Thus, even for a single combustion event, the fuel that is injected may be injected from the port injector and the direct injector at different timings. Additionally, for a single combustion event, multiple injections of the delivered fuel may be performed per cycle. The multiple injections may be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0057] As described above, Figure 2Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder may similarly include its own set of intake / exhaust valves, fuel injector(s), spark plug, etc. It should be appreciated that the engine 10 may include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12 or more cylinders. Additionally, each of these cylinders can include some or all of the various components described and depicted by reference to cylinder 30 by Figure 2 some or all of those described and depicted.

[0058] The engine may also include one or more exhaust gas recirculation passages for recirculating a portion of the exhaust from the engine exhaust to the engine intake device. Thus, by recirculating some of the exhaust, engine dilution can be affected, which can improve engine performance by reducing engine knock, peak cylinder combustion temperature and pressure, throttle losses, and NOx emissions. In the depicted embodiment, the exhaust may be recirculated from the exhaust passage 35 (e.g., downstream of the turbine 116) to the intake passage 42 (e.g., upstream of the compressor 110) via the EGR passage 241. This configuration may be referred to as a low pressure (LP) EGR system. Additionally, an EGR sensor 245 may be disposed within the EGR passage 241 and may provide an indication of one or more of the pressure, temperature, and concentration of the exhaust gas. Other non-limiting example EGR configurations may include a so-called high pressure (HP) EGR system ( Figure 1 shown in), where the exhaust from the exhaust passage 36 (e.g., upstream of the turbine 116) may be recirculated to the intake passage 43 (e.g., downstream of the compressor 110) via a passage. The amount of EGR provided to the intake passage 42 may be varied by the controller 12 via the EGR valve 243. In some examples, the EGR system may include an EGR cooler and / or an EGR valve.

[0059] The controller 12 is shown as a microcomputer, which includes a microprocessor unit (CPU) 206, input / output ports (I / O) 208, an electronic storage medium for executable programs and calibration values shown as a read-only memory chip (ROM) 210 in this particular example, a random access memory (RAM) 212, a keep-alive memory (KAM) 214, and a data bus. In addition to the signals discussed previously, the controller 12 can receive various signals from sensors coupled to the engine 10, including: a measurement of the engine coolant temperature (ECT) from a temperature sensor 216 coupled to the coolant jacket 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 a sensor 224. The engine speed signal RPM can be generated by the controller 12 from the signal PIP. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of the vacuum or pressure in the intake manifold. Other sensors can include a fuel level sensor and a fuel composition sensor coupled to the fuel tank(s) of the fuel system.

[0060] The storage medium read-only memory chip 210 can be programmed with computer-readable data that represents instructions executable by the microprocessor unit 206 for performing the methods described below and other variations that are foreseen but not specifically listed.

[0061] The controller 12 receives signals from Figure 1 and Figure 2 various sensors, and employs Figure 1 and Figure 2 various actuators to adjust engine operation based on the received signals and instructions stored in the memory of the controller. For example, in response to compressor operation within a margin to the surge limit, the controller can send a signal to an actuator of a sleeve of an active casing treatment device coupled to the compressor to actuate the sleeve to a surge position, at which the surge port of the casing opens and the choke port of the casing closes. As another example, in response to compressor operation within a margin to the choke limit, the controller can send a signal to an actuator of a sleeve of an active casing treatment device coupled to the compressor to actuate the sleeve to a choke position, at which the choke port of the casing opens and the surge port of the casing closes.

[0062] Now turning to Figure 3 , as Figure 1 and Figure 2 shown, Embodiment 300 shows a cross-sectional view of the turbocharger 13. In Figure 1 and Figure 2The components described in Figure 3 will be numbered similarly. Turbine 116 converts the energy of the exhaust gas into rotational energy for rotating drive shaft 19 that is connected to impeller 340. Exhaust gas from exhaust manifold 36 enters turbine housing 380 through turbine inlet 360. The exhaust gas flows through volute channels 382 (e.g., 382a, 382b) that expand through turbine outlet 365, and exits through exhaust passage 35. The exhaust gas flowing through turbine 116 generates a force on one or more vanes 370 that are coupled to hub 390, causing one or more vanes 370, hub 390, and drive shaft 19 to rotate. In

[0063] Compressor 110 includes impeller 340, diffusers 330 (e.g., 330a, 330b), compressor chambers 322 (e.g., 322a, 322b), active casing treatment device 310, and casing 320. Active casing treatment (ACT) device 310 includes ACT sleeve 311 and ACT sleeve actuating arm 313, via which the position of ACT sleeve 311 can be adjusted. Rotation of impeller 340 draws pressurized air or gas into compressor 110 through compressor inlet 302 of casing 320. As a non-limiting example, the pressurized air or gas can include air from intake passage 42, exhaust gas (such as when EGR is active), gaseous fuel (such as when fuel port injection is used), and combinations thereof. This mixture of incoming gases can be collectively referred to as "gas flow" or "air flow". The gas flows from compressor inlet 302 and is accelerated by impeller 340 through diffusers 330 into compressor chambers 322. Diffusers 330 and compressor chambers 322 decelerate the gas, causing an increase in pressure in compressor chambers 322a, 322b. The gas can flow from compressor chambers 322a, 322b to intake manifold 22 under pressure.

[0064] Elements in turbocharger 13 can be described relative to the direction of the gas flow path through turbocharger 13. An element that is substantially in the direction of the gas flow relative to a reference point is downstream of the reference point. An element that is substantially opposite to the direction of the gas flow relative to the reference point is upstream of the reference point. For example, compressor inlet 302 is upstream of impeller 340 which is upstream of diffusers 330. Diffusers 330 are downstream of impeller 340 which is downstream of compressor inlet 302.

[0065] The impeller 340 includes a hub 354, full blades 350, and a splitter 352. The full blades 350 and the splitter 352 are attached to the hub 354. The edge of the full blade 350 that is most upstream in the compressor 110 is the leading edge of the full blade 350. Similarly, the splitter 352 includes a leading edge at the most upstream portion of the splitter 352. The leading edge of the full blade 350 is upstream of the splitter 352. The impeller 340 includes a rotating shaft that is aligned with the rotating shaft for driving the shaft 19 and the turbine hub 390. The rotating shaft is substantially parallel to the gas flow at the compressor inlet and is substantially perpendicular to the gas flow at the diffuser.

[0066] The housing 320 includes a compressor inlet 302, an intake passage 304, a recirculation passage 318, a recirculation port 316, a bleed passage 317, a surge slot 312, and a choke slot 314. The impeller 340 is contained within the intake passage 304. The surge slot 312 is located on the housing 320, downstream of the leading edge of the full blade 350 and upstream of the leading edge of the splitter 352. The choke slot 314 is downstream of the leading edge of the splitter 352 and downstream of the surge slot 312 on the housing 320. The recirculation port 316 is downstream of the compressor inlet 302 and upstream of the impeller 340. The recirculation port 316 is configured such that gas can flow between the intake passage 304 and the recirculation passage 318.

[0067] The active casing treatment device (ACT) 310 includes a plurality of ports 315 cut into the sleeve 311. The active casing treatment device (ACT) 310 is configured to control the gas flow through the compressor 110. Specifically, the active casing treatment device 310, which is controlled by the controller 12 via a signal sent to the ACT sleeve actuator arm 313, can selectively control the gas flow between the intake passage 304 and the recirculation passage 318 through one of the surge slot 312 and the choke slot 314. As detailed below, during conditions when compressor surge can occur, such as during low mass flow conditions, the active casing treatment device 310 can allow gas to flow from the intake passage 304 through the surge slot 312 into the recirculation passage 318. Gas also continues to flow from the recirculation passage 318 through the recirculation port 316 into the intake passage 304. Thus, the gas flow rate impinging on the leading edge of the full blade 350 can be greater than it would be if air were not allowed to flow through the surge slot 312. The additional flow of recirculated gas can enable the turbocharger compressor to operate at a lower air flow rate through the compressor inlet 302 before surge occurs.

[0068] During conditions when compressor choking can occur, such as during high mass flow conditions, the active casing treatment device 310 can enable gas to flow from the impeller to the inlet passage 304 via the choke slot 314 and the recirculation passage 318. During high mass flow conditions, a low pressure region can exist in the inlet passage 304 downstream of the leading edge of the separator 352 adjacent to the choke slot 314. The low pressure region can induce gas to flow from the inlet passage 304 through the recirculation port 316 and the bleed passage 317 into the recirculation passage 318, and then through the choke slot 314 to the impeller. Compared with a compressor without the choke slot 314, the short circuit path through the recirculation passage 318 can enable an increase in the gas flow rate through the compressor during high mass flow conditions. In this way, short circuit flow of the gas can enable more gas to flow before the turbocharger is in a choking condition.

[0069] The inlet passage 304 can be substantially cylindrical. The recirculation passage 318 can be substantially annular because it is external to the inlet passage 304. The ports connecting the inlet passage 304 and the recirculation passage 318 (such as the recirculation port 316, the bleed passage 317, the choke slot 314, and the surge slot 312) can each be implemented in various means. For example, the ports can be configured as one or more holes formed in the casing. As another example, the ports can be configured as one or more slots extending around the circumference of the inlet passage. Along the length of the ports from the inlet passage 304 to the recirculation passage 318, the ports can have a uniform or non-uniform width. Each port can have a centerline extending along the length of the port from the inlet passage 304 to the recirculation passage 318. The centerline can be orthogonal to the axis of rotation of the impeller 340, or can have a non-zero slope when compared with the normal to the axis of rotation of the impeller 340.

[0070] The active casing treatment device 310 can be implemented in many ways. For example, a slidable casing sleeve 311 can be fitted in the recirculation passage to selectively block the flow of gas through the choke slot 314 and / or the surge slot 312. The casing sleeve can include one or more holes, ports or slots 315, which can be selectively aligned with the choke slot 314 and / or the surge slot 312 according to the position of the casing sleeve. Based on the control signal received from the controller 12, the position of the casing sleeve 311 can be adjusted by the actuation of the ACT sleeve arm 313. For example, in response to a low mass flow condition or a condition when the compressor pressure ratio is within the surge margin to the surge limit, the casing sleeve arm 313 can be actuated via a signal commanded by the controller 12 to a first position where the slot 315 of the casing sleeve is aligned with the surge slot 312 and not with the choke slot 314. As a result, the casing sleeve can be adjusted such that the surge slot 312 is opened and the choke slot 314 is blocked during low mass flow conditions. This allows gas to be recirculated from the impeller to the inlet passage via the recirculation passage, thus moving the compressor operation further away from the surge limit.

[0071] As another example, in response to a high mass flow condition or a condition when the compressor pressure ratio is within the choke margin to the choke limit, the casing sleeve arm 313 can be actuated via a signal commanded by the controller 12 to a second position (different from the first position) where the port or slot 315 of the casing sleeve is aligned with the choke slot 314 and not with the surge slot 312. As a result, the casing sleeve can be adjusted such that the choke slot 314 is opened and the surge slot 312 is blocked during high mass flow conditions. This allows gas to be recirculated from the inlet passage to the impeller via the choke slot passage, thus moving the compressor operation further away from the choke limit.

[0072] In other examples, in response to a command from the controller 12 for adjusting the position of the active casing treatment device, the casing sleeve 310 can slide or rotate such that it does not overlap or obstruct the intended port (e.g., the choke slot 314 or the surge slot 312) in any way, thereby selectively opening the choke slot 314 or the surge slot 312. These positions will be further described with reference to Figure 4A and Figure 4B Further description of these positions. In an alternative embodiment, the active casing treatment device 310 can be adjusted based on the pressure difference across the compressor inlet 304 and both ends of the intake manifold 44. In yet another alternative embodiment, the active casing treatment device 310 can be adjusted based on the pressure difference across the intake manifold 44 and both ends of the turbine inlet 360. It should be understood that these specific embodiments are presented for illustration and are not intended to be limiting in any way.

[0073] Now turning to Figure 4A andFigure 4B , shows an example actuation of a sleeve of a compressor active housing treatment device (such as Figure 3 's ACT sleeve 311) and the resulting flow pattern through the compressor. Figure 4A 's embodiment 400 shows Figure 3 's cross-sectional view, in which the sleeve of the active housing treatment device is in a first position enabling surge control. Figure 4B 's embodiment 450 shows Figure 3 's cross-sectional view, in which the sleeve of the active housing treatment device is in a second position enabling choke control. It should be understood that all components shown in Figure 4A and Figure 4B have been introduced earlier, and thus are not reintroduced here.

[0074] Figure 4A shows a first example positioning 400 of the active housing treatment device 311 in response to a low mass flow condition that can cause the compressor to operate within the threshold of the surge limit. For example, in response to the compressor pressure ratio being within the surge margin to the surge limit, the controller may send a control signal to the ACT sleeve arm 313 to move the ACT sleeve 311 to a first position where the slot 315 overlaps with the surge port 312. In this position, the surge port is open and the choke port is closed. Due to actuating the sleeve to the first position, the active housing treatment device 310 can enable air to flow from the intake passage 304 through the surge slot 312 and the slot 315 into the recirculation passage 318 during low mass flow conditions. As shown by the dashed arrow 452, the airflow then continues to enter the intake passage 304 from the recirculation passage 318 through the recirculation port 316. Therefore, the air charge flow hitting the leading edge of the full blade 350 can be greater than the air charge flow when the surge slot 312 is kept closed / blocked by the sleeve (as Figure 4B shows). The recirculation of the charge can enable the turbocharger compressor to operate with a lower flow rate through the compressor, thereby reducing surge occurrence.

[0075] Figure 4BShows a second example positioning 450 of the active housing treatment device 310 in response to a high-quality flow condition that can cause the compressor to operate within the choke limit threshold. For example, in response to the compressor pressure ratio being within the choke margin to the choke limit, the controller can send a control signal to the ACT sleeve arm 313 to move the ACT sleeve 311 to a second position where the slot 315 overlaps with the choke port. In this position, the surge port is closed and the choke port is open. In particular, during high-quality flow conditions, a low-pressure zone may exist in the intake passage 304 downstream of the leading edge of the separator 352 adjacent to the choke slot 314. The low-pressure zone may induce gas to flow from the intake passage 304 through the recirculation port 316 into the recirculation passage 318 and back to the intake passage 304 through the choke slot 314, as shown by 452. When compared to a compressor without a choke slot 314, the short-circuit path through the recirculation passage 318 can enable an increase in the gas flow rate through the compressor under high-quality flow conditions. In this way, the short-circuit flow of gas can enable more gas to flow before the turbocharger reaches the choke condition.

[0076] It should be understood that Figure 3 and Figure 4A and Figure 4B the ACT mechanism depicts a movable sleeve in a three-position system, and the movable sleeve adjusts the opening degrees of two different flow channels (i.e., the choke slot and the surge slot) in the compressor. Here, the three positions are the nominal position (where both the choke slot and the surge slot are closed), the first surge position (where only the choke slot is closed), and the second choke position (where only the surge slot is closed). However, in an alternative embodiment, the ACT mechanism can be coupled in a two-position system that has only one controlled slot (i.e., the choke slot). In that case, the two positions are the nominal position (where the choke slot is closed) and the first choke position (where the choke slot is open), and where the surge slot is uncontrolled and operates via passive operation, and the default nominal provides an increased surge margin.

[0077] Figure 3 and Figure 4A and Figure 4BAn example configuration showing the relative positioning of various components is presented. At least in one example, if elements are shown as directly contacting or directly coupled to each other, such elements may be referred to as being in direct contact or direct coupling, respectively. Similarly, at least in one example, elements shown as adjacent or proximate to each other may be adjacent or proximate to each other, respectively. As an example, components placed in coplanar contact with each other may be referred to as coplanar contact. As another example, at least in one example, elements positioned such that there is only space between them and no other components may be referred to as such. As yet another example, elements shown above / below each other, on opposite sides of each other, or to the left / right of each other may be referred to as such relative to each other. Additionally, as shown in the figure, at least in one example, the topmost element or point of an element may be referred to as the "top" of the component, and the bottommost element or point of an element may be referred to as the "bottom" of the component. As used herein, top / bottom, up / down, above / below may be relative to the vertical axis of the figure and are used to describe the positioning of elements in the figure relative to each other. Thus, in one example, an element shown above other elements is vertically positioned above the other elements. As yet another example, the shape of the elements depicted in the figure may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, round, chamfered, angled, etc.). Additionally, at least in one example, elements shown as intersecting each other may be referred to as intersecting elements or as intersecting each other. Additionally, in one example, an element shown within another element or shown outside another element may be referred to as such.

[0078] In this way, Figures 1 - 4BThe component provides a supercharged engine system, the supercharged engine system including an engine; an intake compressor having an impeller, a choke slot, a surge slot, an actuatable annular housing that houses the impeller, the housing including a sleeve slot, and an actuator coupled to a sleeve of the housing; an exhaust turbine; an EGR valve coupled in an EGR passage for recirculating exhaust from downstream of the turbine to upstream of the compressor; a pedal for receiving an operator torque demand; and a controller. The controller may be configured with computer-readable instructions stored on a non-transitory memory for: in response to a current change in pedal position, comparing compressor efficiencies with the actuator in the current position relative to each of a first position and a second position, estimating compressor efficiencies with the actuator in the first position and the second position, estimating compressor efficiency based on compressor pressure ratio, mass flow rate, the current change in pedal position, and a history of past changes in pedal position within a given drive cycle; actuating the sleeve via the actuator to one of the first position and the second position having greater compressor efficiency; estimating a boost pressure perturbation associated with the actuation; and adjusting an opening of the EGR valve based on the estimated boost pressure perturbation. The controller may include further instructions for: when the turbine is a wastegated turbine, adjusting an exhaust flow bypassing the wastegated turbine based on the estimated boost pressure perturbation; and when the turbine is a variable geometry turbine, adjusting a blade angle of the turbine based on the estimated boost pressure perturbation. In one example, in the first position, the sleeve slot is aligned with the choke slot, and compressed air is drawn from the compressor inlet into the impeller via the choke slot, and in the second position, the sleeve slot is aligned with the surge slot, and compressed air is recirculated from the impeller to the compressor inlet via the surge slot.

[0079] Now turning to Figure 5 , a flowchart of an example routine 500 is shown that depicts an active housing treatment device for adjusting a turbocharger compressor based on engine operating conditions, a driver model, and predicted engine load. The routine 500 may be performed by a controller (e.g., Figure 1 's controller 12) based on instructions stored on the controller's memory and in conjunction with signals received from sensors of the engine system (such as the sensors described above with reference to Figure 1 and Figure 2 ). The controller may adjust engine operation using an engine actuator of the engine system according to the methods described below. In one example, the controller may control an active housing treatment device (e.g., Figures 1 - 3 's compressor 110) of a turbocharger based on sensor inputs indicative of compressor speed, volumetric flow rate through the compressor, compressor inlet pressure, and compressor outlet pressure. Figure 3Position of the active housing treatment device 310). Specifically, the controller can receive an indication of the compressor speed from a compressor speed sensor (e.g., Figure 1 compressor speed sensor 54), an indication of the compressor inlet pressure from a compressor inlet pressure sensor (e.g., Figure 1 pressure sensor 56), and an indication of the compressor outlet pressure from a throttle inlet pressure sensor (e.g., Figure 1 TIP sensor 58). In one non-limiting example, the controller 12 can use the input data from the aforementioned sensors to determine the pressure ratio to determine the pressure ratio (e.g., compressor outlet pressure divided by compressor inlet pressure). Using the pressure ratio and the compressor speed, the controller 12 can determine the compressor operation relative to the surge limit or the choke limit. In response to an indication that the compressor is operating within a threshold distance of the surge limit, the controller can command the actuator to adjust the position of the active housing treatment device so as to increase the opening of the surge slot (e.g., Figures 3 - 4B surge slot 312 in Figure 3 ), so as to facilitate the recirculation of the air flow through the surge slot into the recirculation passage (e.g., Figure 3 recirculation passage 318 in Figure 3 ), and then through the recirculation port (e.g., Figures 3 - 4B surge slot 314 in Figure 3 ), and back into the intake passage (e.g., Figure 3 intake passage 304 in Figure 3 recirculation port 316 in

[0080] At 502, the program includes estimating and / or measuring engine operating conditions, which include but are not limited to engine speed, operator torque demand, engine coolant temperature (ECT), atmospheric pressure (BP), boost pressure, manifold absolute pressure (MAP), mass air flow rate (MAF), accelerator pedal position (PP), and EGR level (e.g., engine dilution) as may be measured and / or estimated by the outputs of the corresponding sensors as described by reference Figure 1 and Figure 2 ).

[0081] At 504, the routine includes actuating an active casing actuation device (ACT) to a nominal position. In one example, the nominal position may be a surge slot (e.g., Figure 3 surge slot 312) and choke slot (eg, Figure 3 In other words, the nominal position may correspond to an ACT sleeve position that blocks each of the surge slot and choke slot openings, thereby not allowing the intake passage (e.g., Figure 3 The intake passage 304 of the compressor housing and the recirculation passage of the compressor housing (eg, Figure 3 In this way, airflow entering the compressor intake passage may no longer circulate through the choke slot or surge slot. In one example, actuating the ACT to the nominal position may include a vehicle controller (e.g., Figure 3 The controller 12) sends a signal command to the ACT sleeve arm actuator (e.g., Figure 3 The arm 313 of the ACT sleeve is provided to maintain the nominal position and not move to the first position or the second position. In one example, the nominal position is the default position of the ACT sleeve.

[0082] The routine then proceeds to 506 where it includes determining initial EGR and boost actuator settings based on the operating conditions determined at 502. In one example, determining EGR settings may include determining a low pressure (LP) EGR valve (e.g., Figure 2 The controller may also control the opening of the LP EGR valve 243 to reduce the recirculation of exhaust gas. In another example, in response to an acceleration indication such as may be indicated by actuation of an accelerator pedal, the controller may send a signal to the actuator of the LP EGR valve to reduce the opening of the LP EGR valve. In this way, during conditions when the engine is operating in a medium to high speed load region, a reduced amount of exhaust gas may be recirculated from downstream of the turbine to upstream of the compressor. In another example, when the engine is operating in a low to medium speed load region, the LP EGR valve opening may be increased. In other examples, the engine system (e.g., Figure 1 The engine system 100 may include one or more of an LP EGR system and a high pressure (HP) EGR system. Those skilled in the art will appreciate that an LP EGR system includes a system that directs exhaust gas from a turbine (e.g., Figure 2 The turbine 116 is directed downstream to a compressor (eg, Figure 2 The HP EGR system includes routing exhaust gas from upstream of the turbine to downstream of the compressor. It should be appreciated that an EGR valve and EGR passage (e.g., similar to that used in an LP EGR system) may be used.Figure 2 For the EGR valve 243 and the EGR passage 241), the HP EGR system may also include an HP EGR valve for regulating the flow rate through the HP EGR passage. When included, determining the EGR setting may also include determining the appropriate opening of the HP EGR valve in addition to determining the opening of the LP EGR valve.

[0083] For example, LP-EGR may be used only when HP-EGR alone cannot support the EGR requirement. An example EGR control strategy includes adjusting the LP-EGR valve position (in combination with the backpressure valve) so that sufficient LP-EGR flows to meet the shortfall between the EGR requirement and the available HP-EGR. The EGR requirement is typically a function of speed and load to manage the trade-off between NOx emissions from the engine and meeting torque requirements.

[0084] In an example embodiment including a fixed geometry turbine having a wastegate and a wastegate valve, determining the initial boost actuator setting may include determining the appropriate opening of the wastegate valve (e.g., Figure 1 the wastegate valve 92). For example, in response to a decrease in the operator torque demand, such as when the controller receives an indication of an operator pedal release event in response to a sudden release of the accelerator pedal (e.g., Figure 2 the accelerator pedal 232), the controller may send a signal to the actuator of the wastegate valve to increase the opening of the wastegate valve, thereby increasing the flow rate of the exhaust gas through the wastegate bypassing the turbine. By reducing the amount of exhaust gas flowing through the turbine, the turbine speed can slow down more quickly and will not suppress the compressor. As another example, in response to an increase in the operator torque demand, such as when the controller receives an indication of a pedal press event as indicated by the depression of the accelerator pedal, the controller may send a signal to the actuator of the wastegate valve to decrease the opening of the wastegate valve, thereby increasing the flow rate of the exhaust gas through the turbine. By increasing the amount of exhaust gas flowing through the turbine, the turbine speed can increase more quickly and drive the compressor rapidly.

[0085] In another example embodiment including a variable geometry turbine (VGT), determining the initial boost actuator setting may include the controller determining the appropriate vane position of the VGT based on the engine operating conditions and sending a command to the vanes of the VGT to adjust the vane angle to the desired position. In one example, in response to an increase in the operator torque command, the controller may send a signal to adjust the vane angle to decrease the VGT vane opening. In another example, in response to a decrease in the operator torque command, the controller may send a signal to adjust the vane angle to increase the VGT vane opening.

[0086] The routine continues to 508 where the method includes determining a pressure ratio across the turbocharger compressor and a compressor mass flow parameter based on engine operating conditions. The compressor pressure ratio may be defined as the ratio of the pressure at the compressor outlet relative to the compressor inlet pressure. In one example, the output of a compressor inlet pressure sensor (e.g., Figure 1 pressure sensor 56) may provide an indication of the compressor inlet pressure, while the output of a throttle inlet pressure sensor (e.g., Figure 1 TIP sensor 58) may provide an indication of the compressor outlet pressure. In one non-limiting example, the controller 12 may use input data from the aforementioned sensors to determine the pressure ratio. The mass flow parameter may include a mass air flow estimate as determined by a MAF sensor coupled to the engine intake or a mass air pressure estimate as determined by a MAP sensor coupled to the engine intake. Additionally, an indication of the barometric pressure (BP) may also be used to determine the volumetric or mass flow rate through the compressor. Using the pressure ratio and volumetric flow rate data or mass flow rate data, the controller may determine the operating position of the compressor on a compressor map (e.g., Figure 8 compressor map 800). For example, the position of the compressor operation related to the choke limit and surge limit of the compressor may be determined.

[0087] The routine then continues to 510 where the method includes calculating a current compressor efficiency based on the estimated pressure ratio and mass flow parameter (as determined at 508). In one example, when the ACT is in the nominal position at 610, the current compressor efficiency may be the compressor efficiency associated with operating the compressor with the ACT in the nominal position.

[0088] At 512, the method includes predicting a first compressor efficiency with the surge slot of the ACT sleeve open and predicting a second compressor efficiency with the choke slot of the ACT sleeve open. For example, the controller may predict the amount of recirculation flow expected across the compressor impeller, at the current pressure ratio and mass flow rate, through the compressor housing where the ACT sleeve arm is actuated to a position where the surge port is open and the choke port is closed, and predict the resulting change in compressor efficiency from the current compressor efficiency to the first compressor efficiency. Similarly, the controller may predict the amount of forward flow expected through the compressor impeller, at the current pressure ratio and mass flow rate, through the compressor housing where the ACT sleeve arm is actuated to a position where the choke port is open and the surge port is closed, and predict the resulting change in compressor efficiency from the current compressor efficiency to the first compressor efficiency.

[0089] At the end of the choke, further increasing the mass flow rate (when the choke slot is open) can affect the ability to enable HP-EGR flow, and in such a case, the LP-EGR system can be engaged to compensate for the EGR deficiency relative to the desired EGR value. Accordingly, the HP-EGR valve and the LP-EGR valve can be coordinated accordingly. Near the surge limit, the ability to enable HP EGR flow is generally not impaired, and the HP-EGR valve and the VGT vanes can be used to manage surge. During surge mitigation via the surge slot, the HP-EGR valve can be adjusted under conditions of increased air flow to meet the necessary EGR requirements, where the surge slot is active relative to the situation when the compressor would be in surge.

[0090] At 514, the method compares the predicted first compressor efficiency and the second compressor efficiency with the current compressor efficiency (determined at 510) and determines whether at least one of the first efficiency or the second efficiency is higher than the current compressor efficiency with the ACT in the nominal position. If neither the first predicted efficiency nor the second predicted efficiency is greater than the current efficiency, the program proceeds to 520, where the method includes maintaining the operation of the compressor with the ACT in the nominal position. In other words, in response to the current compressor efficiency being high, the ACT is maintained in the nominal position, and it is inferred that neither surge assistance nor choke assistance is required. Additionally, the EGR and boost actuator settings associated with the ACT in the nominal position are also maintained. In other examples, the controller can select the maximum of the first efficiency, the second efficiency, and the current efficiency and command a signal to switch to the corresponding mode (normal, choke slot open, or surge slot open) by actuating the ACT accordingly.

[0091] If the first efficiency or the second efficiency predicted at 514 is higher than the current compressor efficiency, it can be inferred that the compressor operation is moving towards the surge limit or the choke limit (based on the higher of the predicted first compressor efficiency and the second compressor efficiency). Upon confirmation, at 516, the method includes determining whether an ACT adjustment condition is met. It should be understood that the ACT adjustment condition can be different based on the highest of the first efficiency and the second efficiency. To reduce the likelihood of flow pulsations and efficiency degradation associated with each ACT adjustment, the frequency of ACT actuation can be limited. In one example, the ACT adjustment condition can be confirmed if a threshold duration has elapsed since the last ACT actuation. In another example, the ACT adjustment condition can include one or more of the engine coolant temperature being within a specified temperature range, the vehicle speed being within a specified speed range, the engine load being within a specified load window, and the instantaneous boost engine operation being within a specified boost pressure range.

[0092] For example, the first efficiency may be the efficiency estimated at the surge line at a given operating point (pressure ratio). The second efficiency may be evaluated from the choke line associated with the given operating point.

[0093] As an example, the surge margin may be determined as:

[0094] Surge margin = (mass flow rate_nominal – mass flow rate_surge line) / (mass flow rate_nominal),

[0095] where mass flow rate_nominal is the nominal mass flow rate and mass flow rate_surge line is the mass flow rate at the surge line. All mass flows may be calculated at the same corrected compressor speed according to the compressor map. The choke margin may be determined similarly. A decision threshold for these margins (regarding when to actuate the ACT) can then be set to a value determined based on fresh air demand and altitude. The map-based approach allows for flexibility in introducing non-linear thresholds (such as a fixed offset (margin) in some conditions) and linear varying offsets in other conditions (e.g., proportional to the flow at surge). For example, a fixed margin threshold (offset) may be set in low flow conditions. Efficiency measures may also be used and, similarly, efficiency measures may be derived from the compressor map for the surge position and the choke position and compared to the efficiency at the current operating point. The rate of decrease of these margins (based on mass flow or based on efficiency) along with the threshold margin may also be used to trigger ACT actuation.

[0096] If the ACT adjustment condition corresponding to the higher of the first efficiency and the second efficiency is met, the program proceeds to 518, where the program includes actuating the ACT to a position corresponding to the higher of the predicted first efficiency and the second efficiency. Also at 518, the method includes adjusting the EGR and boost actuator settings based on the selected ACT position to operate the compressor at the highest efficiency. In one example, if the current efficiency for a given operating condition is 0.70, the first predicted compressor efficiency for the open ACT surge slot is 0.75, and the second predicted compressor efficiency for the open ACT choke slot is 0.65, the controller may infer that the compressor may become surge limited and thus may command the ACT arm to be actuated to adjust the ACT sleeve position to the position where the surge slot is open, because this configuration provides the highest possible efficiency for the given operating condition. In response to actuating the ACT to the position where the surge slot is open, the controller may command an adjustment to one or more of the EGR valve and boost actuator settings in order to maintain combustion stability and compressor efficiency, as well as control emissions. For example, when operating with the surge slot open, the exhaust gas valve opening may be increased to reduce the exhaust flow through the turbine, and the HP-EGR valve opening may be decreased to reduce the high-pressure exhaust gas recirculation to the intake device. In another example, if the current efficiency for a given operating condition is 0.70, the first predicted compressor efficiency for the open ACT surge slot is 0.65, and the second predicted compressor efficiency for the open ACT choke slot is 0.75, the controller may infer that the compressor may become choke limited and thus may command the ACT arm to be actuated to adjust the ACT sleeve position to the position where the choke slot is open, because this configuration provides the highest possible efficiency for the given operating condition. In response to actuating the ACT to the position where the choke slot is open, the controller may command an adjustment to one or more of the EGR valve and boost actuator settings in order to maintain combustion stability and compressor efficiency and control emissions. For example, when operating with the choke slot open, the exhaust gas valve opening may be decreased to increase the exhaust flow through the turbine, and the HP-EGR valve opening may be increased to increase the high-pressure exhaust gas recirculation to the intake device. In this way, the controller may include logic for comparing the compressor efficiency in the open and closed slot conditions to determine whether a change in the state of the ACT is needed.

[0097] If the ACT adjustment condition is not met at 516, the method moves to 520, where the turbocharger operation is maintained with the ACT in the nominal position, after which the program ends. Here, even though higher efficiency could be provided by actuating the ACT position, the ACT is maintained in the nominal position to reduce exhaust flow pulsations and NVH issues. It should be understood that maintaining operation with the ACT in the nominal position may also include maintaining the current or initial EGR and boost actuator settings (such as those determined at 506).

[0098] In this way, by adjusting the slot control (open or closed) via ACT sleeve position adjustment in response to a change in driver demand, which results in a change in boost demand, driver demand can be met without adversely affecting compressor performance. Now turning to Figure 6 , method 600 depicts another embodiment of a method for controlling ACT position to increase turbocharger compressor efficiency. Method 600 may also depict an example implementation of a control program in response to a determined or predicted choke condition or surge condition Figure 5 .

[0099] At 602, the program includes estimating and / or measuring engine operating conditions, which include but are not limited to engine speed, operator torque demand, engine coolant temperature (ECT), atmospheric pressure (BP), boost pressure, ACT position, manifold absolute pressure (MAP), mass air flow rate (MAF), accelerator pedal position (PP), and EGR level (e.g., engine dilution) as may be measured and / or estimated by the output of one or more sensors such as those described by reference Figure 1 and Figure 2 .

[0100] At 604, as at 504, the program includes actuating the active casing treatment device (ACT) to a nominal position. In one example, actuating to the nominal position of the ACT may include the controller sending a command signal to an actuator of an arm coupled to the ACT sleeve to move the ACT sleeve to a first position where both the surge slot and the choke slot of the ACT are closed. As a result, the charge air flow through the compressor impeller is maintained at a nominal level.

[0101] At 606, as at 506, the program includes determining an initial desired EGR and boost actuator setting based on the estimated and / or measured engine operating conditions including the nominal position of the ACT. Determining the initial desired EGR setting may include, for example, determining an LP EGR valve setting and an HP EGR valve setting based on a look-up table stored in the controller's memory as a function of engine speed and load. In which, engine speed and load are used as inputs and the target EGR valve position is provided as an output. The controller may then send command signals to the LP EGR valve actuator and the HP EGR valve actuator to move them to the target settings.

[0102] At 607, the method includes dynamically updating the choke margin and surge margin of a compressor (herein a variable geometry compressor or VGC) based on various driving parameters. The various driving parameters can include driving conditions such as road grade, altitude, ambient temperature and humidity, terrain, local weather conditions, traffic conditions, etc. Additionally, the various driving parameters can include driver behavior in the current driving cycle, and the driver's driving history including the energy density of the driver's pedal demand.

[0103] In one example, if preview information is available, such as available in the case of a connected vehicle using V2V, V2I, GPS, or related technologies, the altitude and road grade can be established in advance. Thus, given a driving route, the controller can establish the road grade and altitude achieved on the route from mapping and positioning data. If the preview information is not available, the information can be retrieved via the vehicle's navigation system. For example, the current GPS position retrieved from an in-vehicle navigation system can be used to determine the altitude and road grade profile in real time. The altitude can also be determined from in-vehicle atmospheric pressure measurements. Thus, the determination of the current altitude and the rate of change of the current altitude (if measurably significant) can allow prediction of the expected altitude within a given projection window of the route (e.g., within a predetermined distance or duration before the current position along the planned route).

[0104] In one example, in response to a predicted increase in road grade due to an upcoming uphill drive, the controller can infer an increase in load and altitude, where the compressor may become choke limited. Thus, the controller can increase the surge margin to the choke limit while maintaining the surge margin to the surge limit. As a result, the ACT can be actuated to a position where the choke slot opens earlier in the driving cycle and can be held at the choke slot until later in the driving cycle. As another example, in response to a predicted decrease in road grade due to an upcoming downhill drive, the controller can infer a decrease in load, where the compressor may become surge limited. In particular, there can be an instantaneous operation from a high load to a low load, which can cause a rapid transition to a low air flow rate, thus causing the compressor to operate in a surge-limited manner. Thus, the controller can increase the surge margin to the surge limit while maintaining the choke margin at the choke limit. As a result, the ACT can be actuated to a position where the surge slot opens earlier in the driving cycle and can be held at the surge slot until later in the driving cycle.

[0105] This operation can be modified by driver behavior learned (through pedal actions) during a period of time prior to the current state in the same driving cycle, as well as previous driving history within one or more additional driving cycles prior to the current driving cycle. In this regard, a continuous time series of the energy density of the driver's pedal demand can be maintained within a coherent time window. The pedal energy density for the driver can be calculated during the driving duration based on the frequency of application of the accelerator pedal and the brake pedal, the duration of application of the accelerator pedal and the brake pedal, and the distance or degree to which the pedal is depressed when the pedal is applied. Driver behavior can also be filtered to allow for smooth engagement / disengagement profiles.

[0106] For example, the following equation can be used to calculate the energy density:

[0107]

[0108] where x is the pedal position. Based on the E metric, a barrier function can be designed to affect the actuation frequency of the ACT. For high f(E) values, the ACT can be allowed to operate with its full available bandwidth. For low (E) values, a slower transition of the ACT position can be enforced by either enforcing a debounce (delay) or by controlling the bandwidth of the ACT actuation to a low value. Thus, if we consider a simple first-order actuation model:

[0109]

[0110] then the bandwidth can be controlled by a parameter τ that is directly a function of E, or modified based on the barrier function f(E). It should be noted that increasing the surge margin will have a similar effect, in that it will cause the ACT to engage the surge slot earlier and release the surge slot later, thus reducing the transition frequency. By limiting the frequency of ACT operation, the barrier function method additionally provides a smoother transition between ACT positions.

[0111] At Figure 10 a mapping diagram 1000 shows an example barrier function. The function (f(E)) serves as a modifier for varying the frequency of ACT operation.

[0112] When the operator frequently applies the accelerator pedal and the brake pedal and / or applies the pedal to a greater extent, a high pedal energy density can be learned. A higher pedal energy density can imply aggressive driving behavior, and the compressor is more likely to enter surge. In response to driving behavior including a higher pedal energy density, the controller can increase the surge margin to the surge limit, causing the ACT to be actuated to a position where the surge slot is opened earlier to provide greater surge protection. Additionally, the ACT can be held in the surge slot for a longer time, such as even after resolving surge when surge is anticipated to recur.

[0113] It should be understood that each of the choke margin and the surge margin can also be adjusted dynamically based on the measured frequency of sleeve actuation within a drive cycle. As detailed below, as the measured frequency exceeds a threshold frequency, the surge margin can increase and the choke margin can decrease. For example, if the surge slot is actuated very frequently, the margin can increase. Increasing the surge margin can have a similar effect in that it will cause the ACT to engage the surge slot earlier and release the surge slot later, thereby reducing the transition frequency.

[0114] Determining an initial desired boost actuator setting can include determining, such as based on a look-up table stored in the controller's memory as a function of engine speed and load, a suitable opening of the exhaust gas valve and / or a target vane angle for the VGT. In this case, the engine speed and load are used as inputs, and the target exhaust gas valve position or vane angle is provided as an output. The controller can then send a command signal to the exhaust gas valve or VGT actuator to move them to the target setting.

[0115] At 608, the program includes determining whether there is a detected or predicted torque increase. In one example, a detected torque increase can be the result of pedal application as indicated by an increased actuation of the accelerator pedal. A predicted torque increase can occur in response to an input signal from one or more remote sources (e.g., an external network cloud, other vehicles, infrastructure) outside the vehicle using one or more technologies (e.g., wireless communication, navigation system, GPS, V2V, V2I). In this way, various types of data including but not limited to slope map data and upcoming traffic conditions can be exchanged between the vehicle and the network cloud, and this data can be used to predict future engine operating conditions. In one example, based on an input from a navigation system (e.g., Figure 1 navigation system 154), the controller can identify an expected driving route (e.g., based on a previous driving history along the same route). Specifically, the controller can "learn" that at a particular location on the route, there is a steepness and the driver will predictably downshift and / or increase acceleration to maintain a suitable speed on the grade. In this way, the controller can store this "predictability" of the driver's habits and other information as a driver model and use the driver model in combination with predicted route, grade, and elevation information to predict future engine operating conditions. In response to an indication that the vehicle position is approaching the location of the grade, the controller can indicate a predicted torque increase.

[0116] If there is no detected or predicted torque increase, the program proceeds to 610, where the program includes determining whether there is a detected or predicted torque decrease. A detected torque decrease can occur as a result of the operator reducing actuation of the accelerator pedal (e.g., lifting off the pedal) or as a result of the vehicle traveling along a route with a suddenly decreasing grade. In one example, this can include the vehicle traveling uphill along a steep grade (e.g., an incline) and suddenly reaching the top of the hill, where a reduced amount of torque is required to maintain the desired vehicle speed.

[0117] If there is no detected or predicted torque decrease, the program proceeds to 612, where the compressor continues to operate with the ACT in its current position. In the example described, the current position can be the default nominal position.

[0118] If the controller receives an indication of a detected or predicted torque decrease, the program advances to 622, where the program includes determining whether a surge condition is detected or predicted. A surge condition can be indicated by a mass air flow rate below a threshold, as indicated by a mass air flow sensor (e.g., Figure 1 the MAF sensor 57). During a surge condition, the air flow through the compressor can become stagnant and reverse, causing the compressor to become unstable and resulting in power loss as a result of reduced compressor performance. In one example, a surge can occur when the throttle is closed in response to lifting off the pedal after a boosted engine condition, referred to as lift-off surge. In other examples, a surge can be caused in part by a high level of cooled low-pressure exhaust gas recirculation (LP EGR) entering upstream of the compressor. A high level of EGR can increase the compressor pressure while reducing the mass flow through the compressor, causing the compressor to operate inefficiently or in the surge region.

[0119] If a surge condition is detected, the program proceeds to 624, where the controller determines whether a threshold frequency of ACT actuation has been met. To avoid compressor flow pulsations and resulting efficiency losses caused by frequent ACT actuation events, further ACT actuation is delayed if the frequency of ACT actuation is already at the threshold level. Thus, if the threshold frequency of ACT actuation has been met, the method moves to 617 to delay ACT actuation. In one example, ACT actuation can be delayed until a threshold duration has elapsed since the last ACT actuation. If a surge condition is not detected, the current ACT position is maintained at 615.

[0120] In one example, the threshold reflects the previous frequency of sleeve actuation and is determined based on the estimated energy density of the driver pedal demand. For example, the threshold can decrease as the estimated energy density increases.

[0121] If the threshold frequency for ACT actuation has not been met, the program proceeds to 626 to actuate the ACT to the position where the surge slot (e.g., Figure 3 surge slot 312) of

[0122] is opened. In one example, actuating the ACT to open the surge slot includes the controller sending a command signal to an actuator coupled to the ACT sleeve arm to actuate the ACT sleeve to a first position where the sleeve slot aligns with the surge slot of the housing. As a result, the surge slot opens while the choke slot remains closed. By virtue of the opening of the surge slot during low mass flow conditions when surge is predicted or detected, the active housing treatment device can enable gas to flow from the compressor inlet passage through the impeller blades, through the surge slot, then through the recirculation passage, and finally back to the compressor inlet passage through the recirculation port. Thus, the gas flow striking the leading edge of the full blades of the compressor can be greater than the gas flow without the increased opening of the surge slot. The additional recirculation flow can enable the turbocharger compressor to operate at a lower gas flow rate through the compressor impeller before surge occurs. As a result of actuating the ACT to open the surge slot, the compressor performance near the surge condition can be improved.

[0123] Next, at 628, the program includes adjusting the EGR flow and the expansion through the turbocharger to mitigate any flow and boost pressure disturbances caused by the actuation of the ACT, thereby enabling a substantially constant flow to be maintained through the ACT actuation. In one example, adjusting the EGR flow in response to actuating the ACT to the position where the surge slot is opened includes increasing the opening of the LPEGR valve (to increase the recirculation of low-pressure exhaust gas to a position upstream of the compressor), and decreasing the opening of the HP EGR valve (to decrease the recirculation of high-pressure exhaust gas to a position downstream of the compressor). Adjusting the expansion through the turbocharger can include increasing the opening of the wastegate valve of a fixed geometry waste-gated turbine to reduce the exhaust gas flow through the turbine (and increase the exhaust gas flow bypassing the turbine). Alternatively, adjusting the expansion through the turbocharger can include increasing the blade angle of the vanes of a variable geometry turbine. In this way, the wastegate valve opening may not have to be opened to the extent it would have without the ACT actuation. After 628, the program ends.

[0123] In one example, by coordinating the adjustment of the ACT position with the EGR and boost actuator adjustments, surge can be addressed using less aggressive actuator adjustments. For example, surge can be addressed by increasing the opening of the wastegate valve to a partially open position without having to fully open the wastegate valve (as would be required if the ACT position adjustment were not applied). Similarly, surge can be addressed by reducing the opening of the HP EGR valve to a partially open position without having to fully close the HP EGR valve (as would be required if the ACT position adjustment were not applied). As a result, the turbine speed does not drop rapidly. If the driver changes their mind during pedal release (which induces surge), or if there is a pedal application soon after pedal release, the wastegate valve can be actuated quickly to the fully closed position and turbine spin-up can be provided more quickly. Similarly, the HP EGR valve can be actuated quickly to the fully open position and the compressor outlet pressure can rise rapidly.

[0124] Returning to 608, if an increase in the detected or predicted torque is confirmed, the program proceeds to 614 to determine whether a choke condition has been detected or predicted. A choke condition can occur when the mass air flow rate through the compressor cannot be increased for a given speed of the compressor. The flow rate into the compressor can be limited by the compressor inlet size, and when the flow at the inlet reaches sonic speed, the flow through the compressor cannot be increased further. A choke condition can be detected based on sensor input from a mass air flow sensor being above a threshold flow rate. Additionally, a choke condition can be indicated based on the pressure ratio across the compressor relative to a compressor map. Based on the pressure ratio, if the compressor is within the choke margin (or less than a threshold distance) of the choke limit, a choke can be predicted. In one example, a choke can be predicted when the engine is operating at high load (such as during trailer towing). As another example, a choke can be predicted when the engine is operating at high altitude with an increasing load, such as during a hill climb.

[0125] If a choke condition is detected, the program proceeds to 616 where the controller determines whether a threshold frequency of ACT actuation has been met. To avoid compressor flow pulsations and the resulting efficiency losses caused by frequent ACT actuation events, further ACT actuation is delayed if the frequency of ACT actuation is already at a threshold level. Thus, if the threshold frequency of ACT actuation has been met, the method moves to 617 to delay ACT actuation. In one example, ACT actuation can be delayed until a threshold duration has elapsed since the last ACT actuation. If a choke condition is not detected, the current ACT position is maintained at 615.

[0126] In one example, the threshold reflects a previous frequency of sleeve actuation and is determined based on an estimated energy density of driver pedal demand. For example, the threshold may decrease as the estimated energy density increases.

[0127] If the threshold frequency for ACT actuation has not been met, the program proceeds to 628 to actuate the ACT to the position where the choke slot (e.g., Figure 3 the surge slot 314) is opened. In one example, actuating the ACT to open the choke slot includes the controller sending a command signal to an actuator coupled to the ACT sleeve arm to actuate the ACT sleeve to a second position where the sleeve slot is aligned with the choke slot of the housing. As a result, the choke slot opens while the surge slot remains closed. By virtue of the opening of the choke slot during a high mass flow condition when choking is predicted or detected, the active housing treatment device enables gas to flow from the compressor inlet passage through the recirculation passage, through the recirculation port, and through the choke slot. Thus, the gas flow hitting the leading edge of the full blades of the compressor can be less than the gas flow without an increased opening of the choke slot. The diversion of the incoming air flow enables the turbocharger compressor to operate at a higher gas flow rate through the compressor prior to the occurrence of choking. As a result of actuating the ACT to open the choke slot, the compressor performance near the choking condition can be improved.

[0128] Next, at 620, the program includes adjusting the EGR flow and the expansion through the turbocharger to mitigate any flow and boost pressure disturbances caused by the actuation of the ACT, thereby enabling a substantially constant flow to be maintained through the actuation of the ACT. In one example, adjusting the EGR flow in response to the ACT being actuated to the position where the choke slot is opened includes decreasing the opening of the LP EGR valve (to reduce the recirculation of low-pressure exhaust gas to a position upstream of the compressor), and increasing the opening of the HP EGR valve (to increase the recirculation of high-pressure exhaust gas to a position downstream of the compressor). Adjusting the expansion through the turbocharger may include decreasing the opening of the wastegate valve of a fixed geometry wastegated turbine to increase the exhaust gas flow through the turbine (and decrease the exhaust gas flow bypassing the turbine). Alternatively, adjusting the expansion through the turbocharger may include decreasing the blade angle of the vanes for a variable geometry turbine. After 620, the program ends.

[0129] In one example, by coordinating adjustments to the ACT position with EGR and boost actuator adjustments, it is possible to resolve chugging using less aggressive actuator adjustments. For example, chugging can be resolved by reducing the opening of the exhaust gas valve to a partially open position without having to fully close the exhaust gas valve (as would be required if ACT position adjustment were not applied). Similarly, chugging can be resolved by increasing the opening of the HP EGR valve to a partially open position without having to fully open the HP EGR valve (as would be required if ACT position adjustment were not applied). As a result, if the driver changes their mind during pedal application (pedal application induces chugging), or if there is a pedal release soon after pedal application, the exhaust gas valve can be actuated quickly to the fully open position and turbine rotation slowdown can be provided more quickly. Similarly, the HP EGR valve can be actuated quickly to the fully closed position and the compressor outlet pressure can be rapidly reduced.

[0130] Due to the ACT being actuated to the surge slot at 618 or the chug slot at 626, the flow across the compressor and the pressure ratio across the compressor change, causing the position of the compressor's efficiency curve on the compressor map to also change, as discussed below with reference to Figure 8 As discussed. The feedback controllers for the EGR flow rate and boost pressure can then actuate the EGR valve and variable geometry turbine (VGT) to compensate for these changes, as discussed above at 620 and 628. Thus, the change in the VGC position due to ACT adjustment can temporarily perturb the engine gas flow properties away from their desired set points (such as the initial set determined at 606). Thus, control actions may need to account for the impact of ACT actuation on the conventional air path parameters.

[0131] It should be understood that while the examples discussed at 620 and 628 involve EGR flow through the EGR valve (HP EGR valve and / or LP EGR valve), in other examples, in addition to the EGR valve, the air flow can be actuated by the intake throttle to compensate for the perturbations caused by ACT actuation.

[0132] In one example, when the ACT is actuated to bring it closer to the final predicted and optimal position, the perturbations are pre-empted by calculating the adjustments to the EGR valve and VGT (vane angle and / or exhaust gas valve position). If the expected changes in the mass air flow (or EGR flow if this is the feedback control variable) and boost pressure (or exhaust pressure if this is the feedback control variable) are depicted as:

[0133]

[0134] And if the sensitivities of dF, dp with respect to EGR valve and VGT actuation are depicted as:

[0135]

[0136] The controller can then adjust the EGR and VGT positions by applying the following equation:

[0137]

[0138] This adjustment will largely correct the perturbations caused by ACT actuation and maintain a constant pressure flow during ACT adjustment. The adjustment may not be perfect, and the feedback controller may still have to ensure accurate regulation. However, the adjustment enables most of the perturbations to be corrected.

[0139] Also at 620 and 628, the controller can adjust the exhaust gas flow through the turbine to compensate for a predicted change in boost pressure due to actuation of the sleeve. For example, in response to the sleeve being actuated to the first surge position, the controller can decrease the vane angle or nozzle angle of the variable geometry turbine, the decrease being based on the predicted change in boost pressure due to actuating the sleeve to the first position. In contrast, in response to the sleeve being actuated to the second choke position, the controller can increase the vane angle of the variable geometry turbine, the increase being based on the predicted change in boost pressure due to actuating the sleeve to the second position. Increasing the flow with the choke slot open can decrease the boost pressure. Thus, if the boost pressure deviation exceeds the desired, the turbocharger speed can be increased via VGT vane control (to or towards the closed position) to achieve the desired boost set point. With the surge slot open, the goal can be to decrease the boost pressure and move the compressor out of surge. In this case, the turbocharger speed can be decreased via VGT vane opening.

[0140] In this manner, the controller can dynamically perform each of the following based on driver behavior including the energy density of the driver pedal demand: adjust the choke margin to the choke limit of the compressor and adjust the surge margin to the surge limit of the compressor; in response to compressor operation within the choke margin, actuate the sleeve of the compressor's active housing to the choke slot; and in response to compressor operation within the surge margin, actuate the sleeve to the surge slot. Actuation can be performed in response to a change in driver pedal demand, and the controller can also estimate the energy density of the driver pedal demand based on each of the rate, magnitude, and frequency of driver pedal application within a drive cycle. The controller can also adjust each of the EGR actuator and the boost actuator based on this actuation to operate the compressor outside of the choke margin or the surge margin. In one example, the EGR actuator includes one or more of a high-pressure EGR valve and a low-pressure EGR valve, the high-pressure EGR valve recirculates exhaust from upstream of the exhaust turbine to downstream of the compressor, the low-pressure EGR valve recirculates exhaust from downstream of the exhaust turbine to upstream of the compressor, and the boost actuator includes one of a wastegate valve for diverting exhaust flow to the exhaust tailpipe while bypassing the turbine and a variable geometry turbine actuator for adjusting the blade angle of the turbine nozzle. The adjustment can include: reducing the opening of the low-pressure EGR valve, increasing the opening of the high-pressure EGR valve, reducing the opening of the wastegate valve, and reducing the nozzle angle in response to the sleeve being actuated to the choke slot; and increasing the opening of the low-pressure EGR valve, reducing the opening of the high-pressure EGR valve, increasing the opening of the wastegate valve, and increasing the nozzle angle in response to the sleeve being actuated to the surge slot. Herein, each of the surge margin and the choke margin can also be dynamically adjusted based on the measured frequency of sleeve actuation of a drive cycle, with the surge margin increasing and the choke margin increasing as the measured frequency exceeds a threshold frequency. Increasing the surge margin reduces frequent surge slot actuation. Similarly, increasing the choke margin engages the choke slot earlier and reduces driver pedal pumping.

[0141] Figure 7 FIG. 700 shows an example block diagram of a variable geometry compressor control in a turbocharged engine for reducing compressor surge and choke. The control system includes a first sub-loop that includes a dynamic model and estimator shown at 702, control logic and arbitration are performed at a second sub-loop 704, and actuation and sensing data are collected at a third sub-loop 706. Each of the first sub-loop and the second sub-loop is configured to receive input from a human driver 708.

[0142] At the first sub-circuit 702, based on the available measurements, the compressor pressure ratio and the compressor mass flow rate are calculated. These are then used to locate the compressor operating point on the compressor map using a dynamic model and a predictor. For example, when the operating conditions change, the dynamic model and the predictor are used to determine whether it is expected that the compressor will become surge-limited or choke-limited in real time. Additionally, based on the input from the human driver 708, including the frequency and extent of the driver's pedal application, the energy density of the driver's pedal demand can be determined and used to dynamically update the model and the predictor.

[0143] At the second sub-circuit 704, the local surge and choke margins are determined based on the dynamic model and the predictor. This is then used for ACT actuation control. Additionally, the choke margin and the surge margin, as well as the surge limit and the choke limit (e.g., the characteristics of the surge and choke limit curves), can be updated based on the input regarding the driver behavior (such as the energy density of the driver's pedal demand). This enables the controller to better anticipate the surge and choke conditions and adjust the ACT actuation control accordingly. For example, the ACT actuation can be achieved earlier in the drive cycle to the surge position or the choke position, and in response to aggressive driver behavior, the ACT actuation to the surge position or the choke position can be maintained for a longer portion of the drive cycle. Additionally, the ACT actuation control can be adjusted based on the air path interactions, such as the perturbations caused in the EGR flow and the intake flow. Further, the ACT actuation control can be adjusted such that the actuation frequency does not exceed a threshold frequency to reduce the flow pulsations and the compressor efficiency losses.

[0144] The ACT actuation control can be performed based on the input regarding the current ACT position sensed by a sensor coupled to the third sub-circuit 706. Other sensor inputs can also be received. The ACT actuation control output can include a control signal delivered to an ACT actuator, such as an ACT driver, also coupled to the third sub-circuit 706. This enables the ACT actuation, after which the updated ACT position signal is sensed and indicated to the ACT actuation control.

[0145] In this way, the surge margin and the choke margin can be dynamically updated based on the vehicle operating conditions and the driver behavior, and the ACT actuation can be adjusted to reduce the surge and choke events while improving the compressor efficiency.

[0146] Now turning to Figure 8, an example compressor map 800 is shown. A compressor map is a graph that schematically depicts the performance characteristics (including efficiency, mass flow range, and boost pressure capability) of a particular compressor. Map 800 shows the compressor pressure ratio (along the y-axis) of a turbocharger compressor at different compressor flow rates (along the x-axis). Line 802 (solid line) shows the surge limit (e.g., the hard surge limit) of the turbocharger compressor, while line 804 (dashed line) shows the choke limit of the turbocharger compressor. Solid line 806 (only 3 are marked) depicts the constant speed lines of the turbocharger compressor. Compressor operation to the left of the surge limit results in turbocharger compressor operation in the surge region. Similarly, compressor operation to the right of the choke limit 804 results in turbocharger compressor operation in the choke region. Compressor operation in both the surge region and the choke region results in objectionable NVH and potential reduction in boosted engine performance. In one example, the positioning of the compressor operating point on the compressor map can be based on compressor flow information (such as inferred from a MAF or MAP sensor), compressor pressure information (such as inferred from a CIP, TIP, or boost pressure sensor), and ACT position information (such as inferred from an ACT position sensor). Alternatively, parameters can be estimated based on engine operating conditions.

[0147] The controller can determine a surge margin to the surge limit and a choke margin to the choke limit based on engine operating conditions including driver behavior and driving history. For example, the controller can determine a surge margin 807, which is a position on the compressor map that is a threshold distance from the surge limit 802. When the compressor operates outside the surge margin 807, such as when the compressor operates at a distance greater than the threshold distance from the surge limit 802, no surge is detected or predicted. However, when the compressor operates within or at the surge margin 807, such as when the compressor operates at a distance less than the threshold distance from the surge limit 802, a surge is foreseen or predicted. At this time, as discussed earlier, the controller can move the compressor further away from the surge-limited region by actuating the ACT to the surge slot. As an example, the compressor can operate along the compressor efficiency curve 810 within the surge margin 807. In response to the inference of an impending surge, the controller can actuate the ACT of the variable geometry compressor to vary the flow through the compressor, thereby moving the compression operation to the compressor efficiency curve 812, outside the surge margin 807.

[0148] As another example, the controller may determine a choke margin 808, which is a position on the compressor map that is a threshold distance from the choke limit 804. When the compressor operates outside of the choke margin 808, such as when the compressor operates at a distance greater than the threshold distance from the choke limit 804, no choke is detected or predicted. However, when the compressor operates within or at the choke margin 808, such as when the compressor operates at a distance less than the threshold distance from the choke limit 804, a choke is foreseen or predicted. At this time, as discussed earlier, the controller may move the compressor further away from the choke-limited region by actuating the ACT to the choke slot.

[0149] It should be understood that the choke margin to the choke limit may be different in magnitude from the surge margin to the surge limit, and the margins vary based on the operating conditions and driver behavior. As an example, when the driving history indicates that the driver has aggressive driving behavior (e.g., the driver tends to alternate frequently between applying the accelerator pedal and the brake pedal, and / or the driver on average presses the brake pedal and the accelerator pedal down to a greater extent), the controller may infer that the compressor is more prone to surge conditions (due to the frequent pedal releases and presses). Thus, the controller may increase the surge margin to the surge limit while maintaining the choke margin to the choke limit. Alternatively, both the surge margin to the surge limit and the choke margin to the choke limit may be increased, with the degree of increase for each adjusted based on the driving history. For example, as the frequency of pedal application increases during a driving cycle, the (one or more) margins may be further increased. In another example, when the vehicle is operating at a higher altitude (such as when towing at a higher altitude), the controller may infer that the compressor is more prone to choke conditions. This is because the lower oxygen level of the ambient air at higher altitudes causes the compressor to operate closer to the choke limit. Thus, the controller may increase the choke margin to the choke limit while maintaining the surge margin to the surge limit. In this way, the surge margin and the choke margin can be dynamically modeled.

[0150] In additional examples, each of the choke margin and the surge margin may also be dynamically adjusted based on the measured frequency of sleeve actuation within a driving cycle. For example, as the measured frequency exceeds a threshold frequency, the surge margin may increase and the choke margin may increase.

[0151] Now turning to Figure 9, the map 900 depicts an example operation of a turbocharged engine system. The example operation includes adjusting the geometry of a variable geometry compressor (VGC) of a turbocharger to reduce surge-limited and choke-limited compressor operation. The geometry of the VGC is adjusted via actuation of the ACT of the compressor. The map 900 includes various engine parameters along the vertical axis and elapsed time along the horizontal axis. The map 900 depicts at graph 902 the accelerator pedal position (PP) indicating the operator torque demand. The map 900 also depicts at graph 904 the boost pressure provided by the VGC, shows at graph 906 the compressor pressure ratio relative to the choke limit 909 and the surge limit 907, shows at graph 908 the ACT actuated to one of three positions (nominal, choke slot, surge slot), shows at graph 910 the position of the HP-EGR valve, and shows at graph 912 the position of the exhaust gas wastegate valve coupled in a bypass across the exhaust turbine of the turbocharger.

[0152] Before time t1, due to the low operator torque demand, the engine operates without boost. The compressor pressure ratio is outside the choke margin and the surge margin. The ACT is positioned at the default nominal position. The HP-EGR valve is closed. The LP-EGR valve (not shown) may be at least partially open. Since boost pressure is not required, the exhaust gas wastegate valve is open.

[0153] At t1, there is an increase in operator torque demand as indicated by a gradual and moderate increase in the accelerator pedal position. In response to the increase in operator torque demand, the boost pressure is increased by moving the exhaust gas wastegate valve to a more closed position to increase the turbine rotation speed. Additionally, the HP-EGR valve opening is increased. The compressor operating point remains outside the choke limit and the surge limit, so the ACT remains in the nominal position. At this position of the ACT, both the surge slot and the choke slot are closed.

[0154] Between t1 and t2, there is another overall increase in operator torque demand. However, this increase in driver demand is an overall more rapid increase in the accelerator pedal position. Additionally, the accelerator pedal is applied and released several times between t1 and t2. In response to the increase in operator torque demand, the boost pressure is further increased by moving the exhaust gas wastegate valve to a more closed position and further increasing the HP-EGR valve opening. The compressor operating point remains outside the choke limit and the surge limit, so the ACT remains in the nominal position.

[0155] Based on the pedal application frequency and degree between t1 and t2, the controller can calculate the pedal energy density and infer that the operator has started to drive more aggressively. Therefore, after t2, the surge limit can be temporarily reduced (thereby reducing the margin to surge), while the choke limit is maintained. In this document, the controller anticipates the possible occurrence of surge based on driver behavior, so by reducing the surge limit, surge control can be initiated earlier in the driving cycle. Shortly before t3, the compressor pressure ratio begins to move closer to the reduced surge limit.

[0156] At t3, there is a decrease in the operator's torque demand as indicated by the sudden release of the accelerator pedal. The sudden drop in torque demand causes the compressor pressure ratio to move into the surge margin and reach the surge limit. If not addressed, the resulting surge (depicted by the dashed line segment 905) will cause NVH problems and a decrease in the performance of the supercharged engine. To address the surge, in response to the decrease in the operator's torque demand, the ACT is actuated to the first position where the ACT engages the surge slot. At this position of the ACT, the surge slot opens while the choke slot closes. This position causes a recirculation flow from the compressor wheel to the compressor inlet, thereby improving the surge margin. Additionally, by moving the exhaust gas valve to a more open position and the HP-EGR valve to a more closed position, the pressure disturbances caused by the ACT actuation are compensated. In this way, the adjustments to the exhaust gas valve and the HP-EGR valve required to address the surge, the drop in torque demand, and compensate for the flow disturbances caused by the ACT actuation are less than those that would be required if the ACT actuation were not performed, as shown by the dashed line segment 911 and the dashed line segment 913. In this manner, by actuating the ACT to the surge slot, the compressor operating point remains outside the surge limit while the air path disturbances caused by the actuation are compensated by the adjustments of the EGR valve and the exhaust gas valve.

[0157] Between t4 and t5, the operator's torque demand remains low and the compressor pressure ratio begins to move further away from the surge limit. Therefore, shortly after t4, once the pressure ratio is sufficiently far from the surge limit, the ACT is actuated back to the nominal position where both the surge slot and the choke slot are open. Additionally, the air path disturbances caused by the actuation are compensated by the adjustments of the EGR valve and the exhaust gas valve. Specifically, the lower torque demand is met by increasing the opening of the exhaust gas valve and decreasing the opening of the HP-EGR valve. Moreover, due to the non-aggressive driving behavior that has persisted since t2, the surge limit increases and returns to an earlier level.

[0158] Shortly before t5, there is an increase in the operator torque demand as indicated by the sudden application of the accelerator pedal. The sudden rise in torque demand causes the compressor pressure ratio to move into the choke margin and reach the choke limit 909. If not addressed, the resulting choke (depicted by the dashed line segment 916) would cause NVH problems as well as a decrease in turbocharged engine performance. To address the choke, in response to the increase in operator torque demand, the ACT is actuated to the second position where the ACT engages the choke slot. At this position of the ACT, the choke slot opens while the surge slot closes. This position causes an increased airflow from the compressor inlet to the compressor impeller, thereby improving the choke margin. Additionally, by moving the exhaust gas valve to a more closed position and the HP-EGR valve to a more open position, the pressure disturbances caused by the ACT actuation are compensated. Thus, the exhaust gas valve and HP-EGR valve adjustments required to address surge, torque demand drop, and compensate for the flow disturbances caused by the ACT actuation are less than those that would be required if the ACT actuation were not performed, as shown by the dashed line segments 914 and 915. In this way, by actuating the ACT to the choke slot, the compressor operating point remains outside the choke limit while the air path disturbances caused by the actuation are compensated by the EGR valve and exhaust gas valve adjustments.

[0159] Between t5 and t6, the operator torque demand remains high and the compressor pressure ratio begins to move further away from the choke limit. Therefore, shortly after t6, once the pressure ratio is sufficiently far from the choke limit, the ACT is actuated back to the nominal position where both the surge slot and the choke slot are open. Additionally, the air path disturbances caused by the actuation are compensated by the EGR valve and exhaust gas valve adjustments. Specifically, by decreasing the opening of the exhaust gas valve and increasing the opening of the HP-EGR valve, the higher torque demand is met.

[0160] In this way, the controller can actuate the sleeve of the variable geometry compressor housing to a position selected based on each of the compressor pressure ratio and the mass flow rate through the compressor; and adjust each of the EGR actuator and the boost actuator based on the selected position to maintain the compressor pressure ratio during actuation. Actuation can include, for example, predicting changes in the compressor surge margin relative to the surge limit and the compressor choke margin relative to the choke limit based on the compressor pressure ratio and the mass flow rate; in response to a predicted decrease in the compressor surge margin, actuating the sleeve to a first position; and in response to a predicted decrease in the compressor choke margin, actuating the sleeve to a second position. In one example, when the sleeve is in the first position, the surge slot of the compressor is open, while the choke slot of the compressor is closed, and compressed air is recirculated from the compressor impeller blades to the compressor inlet via the surge slot, and wherein when the sleeve is in the second position, the surge slot is closed, while the choke slot is open, and compressed air is recirculated from the compressor inlet to the compressor impeller blades via the choke slot. The sleeve can be actuated to the first position before the compressor pressure ratio reaches the surge limit, and the sleeve can be actuated to the second position before the compressor pressure ratio reaches the choke limit. The controller can predict changes in the compressor surge margin or the compressor choke margin based on driver behavior including an estimated energy density of the driver pedal demand. The prediction can also be based on an input from a navigation system, the input including altitude and road grade. In another example, the sleeve position can also be selected based on a previous frequency of sleeve actuation relative to a threshold, the threshold being determined based on the estimated energy density of the driver pedal demand, and the threshold decreasing as the estimated energy density increases. Even when the compressor surge margin or the compressor choke margin decreases, in response to the previous frequency of sleeve actuation being higher than the threshold, the sleeve can be maintained in the current (e.g., nominal) position. In response to no predicted decrease in the compressor surge margin or the compressor choke margin, the controller can also maintain the sleeve in a default position, where both the surge slot and the choke slot are closed. In one example, the compressor is driven by an exhaust turbine, the EGR actuator includes an EGR valve coupled in the EGR passage, the EGR valve recirculates exhaust gas from downstream of the turbine in the exhaust passage to upstream of the compressor, and the boost actuator includes one of a variable geometry turbine and a wastegate valve, the wastegate valve being coupled in a wastegate bypassing the exhaust turbine. The adjustment can include, in response to the sleeve being actuated to the first position, increasing the opening of the EGR valve and increasing the opening of the wastegate valve, the increase being based on a predicted decrease in the boost pressure due to actuating the sleeve to the first position; and in response to the sleeve being actuated to the second position, decreasing the opening of the EGR valve and decreasing the opening of the wastegate valve, the decrease being based on a predicted increase in the boost pressure due to actuating the sleeve to the second position.In another example, the adjustment includes, in response to the sleeve being actuated to a first position, decreasing the vane angle of a variable geometry turbine, the decrease being based on a predicted change in boost pressure due to actuating the sleeve to the first position; and in response to the sleeve being actuated to a second position, increasing the vane angle of the variable geometry turbine, the increase being based on a predicted change in boost pressure due to actuating the sleeve to the second position.

[0161] In this way, the adjustment of the position of the active sleeve housing treatment device can be coordinated with the air flow path actuator adjustment to improve the operation of the variable geometry compressor. By filtering driver behavior and using the energy density of the driver's pedal actuation to adjust the surge limit and choke limit of the compressor in real time, surge and choke can be better predicted and thus the surge margin and choke margin can be dynamically updated. By reducing the surge limit and increasing the allowed margin to surge during conditions when the driver behavior is aggressive, surge mitigation ACT adjustment can be provided earlier and for a longer duration, thereby improving compressor efficiency. In addition, the ACT actuation frequency can be limited, thereby reducing the flow pulsations and efficiency losses associated with the actuation frequency. By adjusting the EGR flow and the boost actuator operation based on the ACT actuation, any flow pulsations or disturbances caused by the ACT actuation can be compensated for, improving the air flow to the compressor. Overall, compressor operation efficiency can be improved even during conditions when choke and surge would occur.

[0162] A method for an engine includes: actuating a sleeve of a variable geometry compressor housing to a position selected based on each of a compressor pressure ratio and a mass flow rate through the compressor; and adjusting each of an EGR actuator and a boost actuator based on the selected position to maintain the compressor pressure ratio during actuation. In a first example of the method, actuating includes predicting a change in a compressor surge margin relative to a surge limit and a compressor choke margin relative to a choke limit based on the compressor pressure ratio and the mass flow rate; actuating the sleeve to a first position in response to a predicted decrease in the compressor surge margin; and actuating the sleeve to a second position in response to a predicted decrease in the compressor choke margin. A second example of the method optionally includes the first example and further includes that when the sleeve is in the first position, a surge slot of the compressor is open while a choke slot of the compressor is closed, and compressed air is recirculated from compressor impeller blades to the compressor inlet via the surge slot, and that when the sleeve is in the second position, the surge slot is closed while the choke slot is open, and compressed air is recirculated from the compressor inlet to the compressor impeller blades via the choke slot. A third example of the method optionally includes one or more of the first example and the second example and further includes that the sleeve is actuated to the first position before the compressor pressure ratio reaches the surge limit, and that the sleeve is actuated to the second position before the compressor pressure ratio reaches the choke limit. A fourth example of the method optionally includes one or more of the first example to the third example and further includes that predicting a change in the compressor surge margin or the compressor choke margin is based on driver behavior including an estimated energy density of a driver pedal demand. A fifth example of the method optionally includes one or more of the first example to the fourth example and further includes that the prediction is further based on an input from a navigation system, the input including altitude and road grade. A sixth example of the method optionally includes one or more of the first example to the fifth example and further includes that a position is selected based on a previous frequency of sleeve actuation relative to a threshold, the threshold being determined according to an estimated energy density of a driver pedal demand, the threshold decreasing as the estimated energy density increases, and that even when the compressor surge margin or the compressor choke margin decreases, the sleeve remains in the current position in response to the previous frequency of sleeve actuation being higher than the threshold. A seventh example of the method optionally includes one or more of the first example to the sixth example and further includes maintaining the sleeve in a default position in response to no predicted decrease in the compressor surge margin or the compressor choke margin, where both the surge slot and the choke slot are closed.The eighth example of the method optionally includes one or more of the first through seventh examples and further includes driving the compressor by an exhaust gas turbine, wherein the EGR actuator includes an EGR valve coupled in an EGR passage that recirculates exhaust gas from downstream of the turbine to upstream of the compressor in the exhaust passage, and wherein the boost actuator includes one of a variable geometry turbine and a wastegate valve, the wastegate valve being coupled in a wastegate bypassing the exhaust gas turbine. The ninth example of the method optionally includes one or more of the first through eighth examples and further includes adjusting including increasing the opening of the EGR valve and increasing the opening of the wastegate valve in response to the sleeve being actuated to a first position, the increase being based on a predicted drop in boost pressure due to actuating the sleeve to the first position; and decreasing the opening of the EGR valve and decreasing the opening of the wastegate valve in response to the sleeve being actuated to a second position, the decrease being based on a predicted increase in boost pressure due to actuating the sleeve to the second position. The tenth example of the method optionally includes one or more of the first through ninth examples and further includes adjusting including decreasing the blade angle of the variable geometry turbine in response to the sleeve being actuated to a first position, the decrease being based on a predicted change in boost pressure due to actuating the sleeve to the first position; and increasing the blade angle of the variable geometry turbine in response to the sleeve being actuated to a second position, the increase being based on a predicted change in boost pressure due to actuating the sleeve to the second position.

[0163] Another method includes dynamically performing each of the following based on driver behavior including the energy density of driver pedal demand: adjusting a choke margin to a choke limit of a compressor and adjusting a surge margin to a surge limit of the compressor; actuating a sleeve of an active housing of the compressor to a choke slot in response to compressor operation within the choke margin; and actuating the sleeve to a surge slot in response to compressor operation within the surge margin. In a first example of the method, the actuation is responsive to a change in driver pedal demand, and the method further includes estimating the energy density of driver pedal demand based on each of a rate, magnitude, and frequency of driver pedal application within a drive cycle. A second example of the method optionally includes the first example and further includes adjusting each of an EGR actuator and a boost actuator based on the actuation to operate the compressor outside of the choke margin or the surge margin. A third example of the method optionally includes one or more of the first example and the second example and further includes where the EGR actuator includes one or more of a high-pressure EGR valve and a low-pressure EGR valve, the high-pressure EGR valve recirculates exhaust from upstream of an exhaust turbine to downstream of the compressor, the low-pressure EGR valve recirculates exhaust from downstream of the exhaust turbine to upstream of the compressor, and where the boost actuator includes one of a wastegate valve for diverting exhaust flow to an exhaust tailpipe while bypassing the turbine and a variable geometry turbine actuator for adjusting a blade angle of the turbine. A fourth example of the method optionally includes one or more of the first example through the third example and further includes where the adjustment includes: decreasing an opening of the low-pressure EGR valve, increasing an opening of the high-pressure EGR valve, decreasing an opening of the wastegate valve, and decreasing the blade angle in response to the sleeve being actuated to the choke slot; and increasing the opening of the low-pressure EGR valve, decreasing the opening of the high-pressure EGR valve, increasing the opening of the wastegate valve, and increasing the blade angle in response to the sleeve being actuated to the surge slot. A fifth example of the method optionally includes one or more of the first example through the fourth example and further includes dynamically adjusting each of the choke margin and the surge margin based on a measured frequency of sleeve actuation of the drive cycle, with the surge margin increasing and the choke margin decreasing as the measured frequency exceeds a threshold frequency.

[0164] A system for an engine may include: an engine; an intake compressor having an impeller, a choke slot, a surge slot, an actuatable annular housing that houses the impeller, the housing including a sleeve slot and an actuator coupled to a sleeve of the housing; an exhaust turbine; an EGR valve coupled in an EGR passage for recirculating exhaust from downstream of the turbine to upstream of the compressor; a pedal for receiving an operator torque demand; and a controller having computer-readable instructions stored on a non-transitory memory for: comparing compressor efficiency with the actuator in a current position relative to each of a first position and a second position in response to a current change in pedal position, estimating compressor efficiency with the actuator in the first position and the second position, estimating compressor efficiency based on a compressor pressure ratio, a mass flow rate, the current change in pedal position, and a history of past changes in pedal position within a given drive cycle; actuating the sleeve via the actuator to one of the first position and the second position having greater compressor efficiency; estimating a boost pressure perturbation associated with the actuation; and adjusting an opening of the EGR valve based on the estimated boost pressure perturbation. In a first example of the system, the controller further includes instructions for: when the turbine is a wastegated turbine, adjusting an exhaust flow bypassing the wastegated turbine based on the estimated boost pressure perturbation; and when the turbine is a variable geometry turbine, adjusting a blade angle of the turbine based on the estimated boost pressure perturbation. A second example of the system optionally includes the first example and further includes where in the first position, the sleeve slot is aligned with the choke slot and compressed air is drawn from the compressor inlet into the impeller via the choke slot, and where in the second position, the sleeve slot is aligned with the surge slot and compressed air is recirculated from the impeller to the compressor inlet via the surge slot.

[0165] In another representation, the vehicle system is a hybrid vehicle system.

[0166] It should be noted that the example programs and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored as executable instructions in a non-transitory memory and can be carried out by a control system including a controller in combination with various sensors, actuators, and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). As such, the various actions, operations, and / or functions shown can be executed in the order shown, in parallel, or in some cases, the various actions, operations, and / or functions shown can be omitted. Similarly, the order of processing is not necessary to achieve the features and advantages of the example embodiments described herein, but is provided for purposes of illustration and description. One or more of the actions, operations, and / or functions shown can be repeated according to the particular strategy used. Additionally, the actions, operations, and / or functions described can be graphically represented as code to be programmed into the non-transitory memory of a computer-readable storage medium for an engine control system, wherein the instructions are executed in a system including various engine hardware components as well as an electronic controller to carry out the described actions.

[0167] It should be understood that the configurations and programs disclosed herein are exemplary in nature and these specific embodiments are not to be considered in a limiting sense as many variations are possible. For example, the above techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of various systems and configurations as well as other features, functions, and / or properties disclosed herein.

[0168] The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to "one" element or "a first" element or the equivalent thereof. Such claims should be understood to include the combination of one or more such elements, neither requiring nor precluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties can be claimed by amending these claims or presenting new claims in this application or a related application. Such claims are also regarded as including within the subject matter of the present disclosure, whether broader, narrower, equal, or different in scope compared to the original claims.

Claims

1. A method for a supercharged engine, comprising: Actuating a sleeve of a variable geometry compressor housing to a position selected based on each of a compressor pressure ratio and a mass flow rate through the compressor; And Adjusting each of an EGR actuator and a supercharging actuator based on the selected position to maintain the compressor pressure ratio during the actuation.

2. The method according to claim 1, wherein the actuation comprises: Predicting a change in a compressor surge margin relative to a surge limit and a compressor choke margin relative to a choke limit based on the compressor pressure ratio and the mass flow rate; Actuating the sleeve to a first position in response to a predicted decrease in the compressor surge margin; And Actuating the sleeve to a second position in response to a predicted decrease in the compressor choke margin.

3. The method according to claim 2, wherein when the sleeve is in the first position, a surge slot of the compressor is open while a choke slot of the compressor is closed, and compressed air is recirculated from compressor impeller blades to a compressor inlet via the surge slot, and wherein when the sleeve is in the second position, the surge slot is closed while the choke slot is open, and compressed air is recirculated from the compressor inlet to the compressor impeller blades via the choke slot.

4. The method according to claim 2, wherein the sleeve is actuated to the first position before the compressor pressure ratio reaches the surge limit, and wherein the sleeve is actuated to the second position before the compressor pressure ratio reaches the choke limit.

5. The method according to claim 2, wherein the predicted change in the compressor surge margin or the compressor choke margin is based on driver behavior, the driver behavior including an estimated energy density of a driver pedal demand, wherein the estimated energy density is based on each of a rate, a magnitude, and a frequency of a driver pedal application within a driving cycle.

6. The method according to claim 5, wherein the prediction is further based on an input from a navigation system, the input including an altitude and a road grade.

7. The method according to claim 5, wherein the position is further selected based on a previous frequency of sleeve actuation relative to a threshold, the threshold being determined according to the estimated energy density of the driver pedal demand, the threshold decreasing as the estimated energy density increases, wherein even when the compressor surge margin or the compressor choke margin decreases, in response to the previous frequency of sleeve actuation being higher than the threshold, the sleeve is maintained in the current position.

8. The method according to claim 3, further comprising: Maintaining the sleeve in a default position in response to no predicted decrease in the compressor surge margin or the compressor choke margin, wherein both the surge slot and the choke slot are closed.

9. The method according to claim 3, wherein the compressor is driven by an exhaust gas turbine, wherein the EGR actuator includes an EGR valve coupled in an EGR passage, the EGR valve recirculating exhaust gas from downstream of the turbine to upstream of the compressor, and wherein the boost actuator includes one of a variable geometry turbine and a wastegate valve, the wastegate valve being coupled in a wastegate bypassing the exhaust gas turbine.

10. The method according to claim 9, wherein the adjustment includes: in response to the sleeve being actuated to the first position, increasing the opening of the EGR valve and increasing the opening of the wastegate valve, the increase being based on a predicted decrease in boost pressure due to the actuation of the sleeve to the first position; and in response to the sleeve being actuated to the second position, decreasing the opening of the EGR valve and decreasing the opening of the wastegate valve, the decrease being based on a predicted increase in boost pressure due to the actuation of the sleeve to the second position.

11. The method according to claim 9, wherein the adjustment includes: in response to the sleeve being actuated to the first position, increasing the nozzle opening of the variable geometry turbine, the increase being based on a predicted change in boost pressure due to the actuation of the sleeve to the first position; and in response to the sleeve being actuated to the second position, decreasing the nozzle opening of the variable geometry turbine, the decrease being based on the predicted change in boost pressure due to the actuation of the sleeve to the second position.

12. A boosted engine system, comprising: an engine; an intake compressor having an impeller, a choke slot, a surge slot, an actuatable annular housing that houses the impeller, the housing including a sleeve slot, and an actuator coupled to a sleeve of the housing; an exhaust gas turbine; an EGR valve coupled in an EGR passage for recirculating exhaust gas from downstream of the turbine to upstream of the compressor; a pedal for receiving an operator torque demand; and a controller having computer-readable instructions stored on a non-transitory memory for: in response to a current change in pedal position, comparing the compressor efficiency of the actuator at the current position relative to each of a first position and a second position, estimating the compressor efficiency of the actuator at the first position and the second position, the compressor efficiency being estimated based on a compressor pressure ratio, a mass flow rate, the current change in pedal position, and a history of past changes in pedal position within a given drive cycle; actuating the sleeve via the actuator to one of the first position and the second position having a greater compressor efficiency; estimating a boost pressure perturbation associated with the actuation; and adjusting the opening of the EGR valve based on the estimated boost pressure perturbation.

13. The system according to claim 12, wherein the controller includes further instructions for: When the turbine is a waste-gated turbine, adjust the exhaust flow bypassing the waste-gated turbine based on the estimated boost pressure perturbation; and When the turbine is a variable geometry turbine, adjust the blade angle of the turbine based on the estimated boost pressure perturbation.

14. The system according to claim 12, wherein in the first position, the sleeve slot is aligned with the choke slot, and compressed air is drawn from the compressor inlet into the impeller via the choke slot, and wherein in the second position, the sleeve slot is aligned with the surge slot, and compressed air is recirculated from the impeller to the compressor inlet via the surge slot.

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