Sensor calibration with end stop detection of an electric boost pressure control flap control system

Abstract

Method comprising: during the calibration of a wastegate position sensor (218): Setting a boost pressure control valve (202) to a first end stop position; Associating a first feedback position with the first end stop position; Setting the boost pressure control valve (202) to a second end stop position; Associating a second feedback position with the second end stop position; and Setting a position sensor gain based on the first feedback position and the second feedback position.

Description

Background and brief description

[0001] Engine boost may be controlled by adjusting an amount of gas flowing through a turbine of a turbocharger, for example, via a wastegate. In one example, the wastegate may include a wastegate valve and a valve seat. The wastegate valve may be actuated by an associated electric actuator. The electric actuator may be controlled to adjust a wastegate position, thereby controlling the amount of gas flowing through the turbine and achieving the desired boost. Electric actuation of the wastegate may provide faster response and more precise position control than a pneumatically actuated wastegate. The faster response and more precise control may increase engine efficiency, fuel efficiency, and emissions control.

[0002] The document DE 2011 084 086 A1 describes a method for adjusting the end position of guide vanes in a turbine of a turbocharging device in an engine system. The guide vanes can be adjusted using an actuator. The end position depends on a position at a design-related end stop and corresponds to a position of the turbine guide vanes with a predetermined gas throughput. To adjust the guide vanes to the end position, the actuator is controlled with a predetermined position value, which holds the guide vanes in the end position. Further prior art relating to the background of the invention is provided by the document DE 10 2009 028 117 A1.

[0003] In one example, an electric actuator used to control the position of a wastegate includes an electric motor that transmits force to a plurality of links coupled to the wastegate. The plurality of links directly actuates the wastegate to adjust the position of the wastegate. The plurality of links allows the electric motor to be located remotely from an exhaust passage where the wastegate is located, thereby reducing the likelihood of degradation of the electric motor due to heat exposure. The electric motor is controlled based on feedback from a position sensor coupled to a transmission output shaft that provides an indication of wastegate position.

[0004] However, the inventors herein have recognized potential problems with such an approach. For example, although the transmission output shaft sensor provides position detection for the transmission output shaft and the wastegate is adjusted based on transmission output shaft position information, the sensor does not provide an indication of a wastegate end stop. More specifically, the wastegate end stop may include a position at which the wastegate properly aligns with the valve seat to prevent gas from flowing through the wastegate. On the other hand, the end stop may include a position at which the wastegate is fully open.

[0005] In the approach described above, the transmission output shaft sensor does not provide an indication of wastegate position in terms of valve seat position. If the wastegate end stop is unknown when the wastegate is commanded to a closed position, the wastegate position may be overadjusted, causing the wastegate to hit the valve seat at a high speed. Overadjusting the wastegate can increase noise, vibration, harshness (NVH), and valve seat wear. In addition, the closed-loop control system may apply too much current to the wastegate, attempting to move the wastegate to a desired stop position that is physically impossible to achieve, resulting in high stress on the entire system.On the other hand, the position of the wastegate may be set too low, resulting in the wastegate not sealing properly with the valve seat, resulting in unwanted gas flow through the wastegate, which reduces boost pressure.

[0006] Additionally, the wastegate and the multiple connecting pieces may be exposed to high temperatures within the turbine, which can affect the accuracy of the position sensor output. For example, the length of the multiple connecting pieces changes with changes in temperature. Under certain conditions, such changes in length may cause the wastegate to reach its end-stop position before that position is indicated by the transmission output shaft sensor.

[0007] Therefore, in one example, some of the above issues may be at least partially addressed by a method comprising: during calibration of a wastegate position sensor: setting a wastegate to a first endstop position, associating a first feedback position with the first endstop position, setting the wastegate to a second endstop position, associating a second feedback position with the second endstop position, and adjusting a position sensor gain based on the first feedback position and the second feedback position.

[0008] The object is to adjust a position sensor gain based on a first and second feedback position signal. This object is achieved by a method having the features of claims 1, 11, and 17.

[0009] By detecting a wastegate end-stop (valve seat) position and providing feedback control of the wastegate relative to the end-stop position, control accuracy can be increased with respect to the alignment of the wastegate with a valve seat to close the wastegate. This reduces high stress between the wastegate and the valve seat, and NVH conditions can be reduced. Furthermore, end-stop detection and corresponding position sensor calibration can increase the accuracy of wastegate lift control, which in turn can increase the accuracy of boost control.

[0010] It will be understood that the above summary is provided to introduce, in simplified form, a selection of concepts that are further described in the following detailed description. It is not intended to identify principal or essential features of the claimed subject matter, the scope of which is defined solely in the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that eliminate potential disadvantages mentioned above or in any part of this disclosure. Brief description of the drawings

[0011] The subject matter of the present disclosure will be better understood by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Fig. 1 illustrates an engine system including a turbocharger according to an embodiment of the present disclosure; Fig. 2 illustrates an electrically actuated wastegate that may be implemented in a turbocharger according to an embodiment of the present disclosure; Fig. 3 illustrates a method for detecting an end stop (valve seat) position of an electrically actuated wastegate according to an embodiment of the present disclosure; Fig. 4 illustrates a method for calibrating a position sensor based on detected (valve seat) positions of a wastegate according to an embodiment of the present disclosure. Detailed description

[0012] Various systems and methods for detecting a wastegate position of a wastegate in a turbine of a turbocharger are provided. The wastegate position may include a position where the wastegate aligns appropriately with a valve seat to substantially prevent gas from flowing through the wastegate (e.g., less than 5% of the total flow). Alternatively, the wastegate position may include a position where the wastegate is fully open.

[0013] In one example, an end-stop detection routine includes commanding a full stroke of the wastegate from a fully open position to a fully closed position. When the wastegate is commanded to an end-stop position, conditions may be checked to determine if the wastegate is actually located at an end-stop position. For example, the plurality of conditions may include a difference between a wastegate feedback position signal and a commanded wastegate position signal in a steady-state condition being greater than a predetermined threshold; a speed of the electric motor being less than a threshold speed (e.g.,substantially zero); and the wastegate feedback position signal value is between an upper threshold indicating that a limit stop position has been reached and a lower threshold indicating a commanded signal to close the wastegate. If all of these conditions are met, then the wastegate can be determined to be at a limit stop position. The wastegate position sensor measurements during this time provide a corresponding voltage that can be associated with the respective limit stop position when the conditions are met.

[0014] End-of-stroke detection can be used in a wastegate position sensor calibration strategy. The wastegate position sensor calibration strategy can be executed throughout engine operation to adapt to physical changes in the wastegate actuator as operating conditions change. Because the wastegate actuator can be subject to high temperatures within the turbocharger, the length of several connectors connecting the wastegate to the electric motor can change, and such length changes can affect the accuracy of the position sensor. Accordingly, the position sensor calibration strategy can be executed throughout operation to maintain the accuracy of the wastegate position sensor output.

[0015] Furthermore, because end-of-stroke detection requires the wastegate to travel a full stroke between a closed position and an open position, such end-of-stroke detection may be disruptive to operation under certain conditions. Accordingly, the end-of-stroke routine may be executed under certain operating conditions where full wastegate travel may have little or no effect on engine operation.

[0016] Fig. 1 is a schematic diagram illustrating an exemplary engine 10 that may be included in a propulsion system of an automobile. The engine 10 is shown with four cylinders 30. However, other numbers of cylinders may be used in accordance with the present disclosure. The engine 10 may be controlled at least in part by a control system including a controller 12 and by input from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Each combustion chamber (e.g., cylinder) 30 of the engine 10 may have combustion chamber walls with a piston (not shown) disposed therein. The pistons may be coupled to a crankshaft 40 such that reciprocating motion of the piston is translated into rotational motion of the crankshaft.The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Furthermore, a starter motor may be coupled to the crankshaft 40 via a flywheel to activate a starting process of the engine 10.

[0017] Combustion chambers 30 may receive intake air from intake manifold 44 via intake passage 42 and expel combustion gases via exhaust passage 48. Intake manifold 44 and exhaust manifold 46 may selectively communicate with combustion chamber 30 via respective intake valves or exhaust valves. In some embodiments, combustion chamber 30 may include two or more intake valves and / or two or more exhaust valves.

[0018] The fuel injectors 50 are directly coupled to the combustion chamber 30 for direct injection of fuel thereinto proportional to the pulse width of the FPW signal received from the controller 12. In this manner, the fuel injector 50 provides what is known as direct injection of fuel into the combustion chamber 30. The fuel injector may, for example, be mounted on the side of the combustion chamber or in the top of the combustion chamber. Fuel may be supplied to the fuel injector 50 via a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail.In some embodiments, the combustion chambers 30 may alternatively or additionally include a fuel injector disposed in the intake manifold 44 in a configuration that provides what is commonly known as port injection of fuel into the intake manifold upstream of each combustion chamber 30.

[0019] Intake passage 42 may include throttle bodies 21 and 23 with throttle discs 22 and 24, respectively. In this particular example, the position of throttle discs 22 and 24 may be varied by controller 12 via signals provided to an actuator included with throttle bodies 21 and 23. In one example, the actuators may be electric actuators (e.g., electric motors), with this configuration commonly referred to as electronic throttle control (ETC). In this manner, throttle bodies 21 and 23 may be operated to vary the intake air provided to combustion chamber 30, among other engine cylinders. The position of throttle discs 22 and 24 may be provided by controller 12 via throttle position signals TP.The intake passage 42 may further include a mass air flow sensor 120 and a manifold air pressure sensor 122 for providing respective MAF (mass air flow) and MAP (manifold air pressure) signals to the controller 12. In some embodiments, one or more of the throttle bodies may be absent.

[0020] Exhaust passage 48 may receive exhaust gases from cylinders 30. Exhaust sensor 128 is shown coupled to exhaust passage 48 upstream of turbine 62 and emissions control device 78. Sensor 128 may be selected from various suitable sensors to provide an indication of an exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (Universal or Wide-Range Exhaust Gas Oxygen), a dual-state oxygen sensor or EGO, a NOx, HC, or CO sensor. Emissions control device 78 may be a three-way catalyst (TWC), a nitrogen trap, various other emissions control devices, or combinations thereof.

[0021] In some embodiments, sensor 128 may include an exhaust temperature sensor configured to measure an exhaust temperature in exhaust passage 48. Alternatively, the exhaust temperature may be inferred based on engine operating conditions such as speed, load, air-fuel ratio (AFR), spark retard, etc.

[0022] The control 12 is in Fig. 1 as a microcomputer having a microprocessor unit 102, input / output ports 104, an electronic storage medium (or storage engine, storage device, etc.) for executable programs and calibration values, shown in this particular example as a read-only memory chip 106, a random access memory 108, a keep-alive memory 110, and a data bus.The controller 12 may receive various signals from sensors coupled to the engine 10 in addition to the previously described signals, including the induced mass air flow (MAF) measurement from the mass air flow sensor 120; the engine coolant temperature (ECT) from the temperature sensor 112, which is schematically illustrated at a location in the engine 10; a profile ignition pickup (PIP) signal from the Hall effect sensor 118 (or other type) coupled to the crankshaft 40; the throttle position (TP) from a throttle position sensor, as explained; and a manifold absolute pressure signal MAP from the sensor 122, as explained. The engine speed signal RPM may be generated by the controller 12 from the PIP signal. The manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of the vacuum or pressure in the intake manifold 44.It should be noted that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor may provide an indication of engine torque. Further, this sensor, along with the sensed engine speed, may provide an estimate of the charge (including air) induced into the cylinder. In one example, sensor 118, which is also used as an engine torque sensor, may generate a predetermined number of equally spaced pulses for each revolution of crankshaft 40. In some examples, read-only storage medium 106 may be programmed with computer-readable data representing instructions executable by processor 102 for performing the methods described below, as well as other variations that are contemplated but not specifically listed.

[0023] The engine 10 may further include a turbocharger 59 having at least one compressor 60 disposed along an intake manifold 44. The compressor 60 may be at least partially driven by a turbine 62 via, for example, a shaft or other coupling arrangement. The turbine 62 may be disposed along the exhaust passage 48. Various arrangements may be provided for driving the compressor. The amount of compression provided to one or more cylinders of the engine via the turbocharger 59 may be varied by the controller 12. In some cases, for example, the turbine 62 may drive an electric generator 64 to power a battery 66 via a turbodrive 68. The power from the battery 66 may then be used to drive the compressor 60 via an electric motor 70.Further, a sensor 123 may be disposed in the intake manifold 44 for providing a boost signal (BOOST) to the controller 12 indicative of a turbocharger pressure level.

[0024] Furthermore, the exhaust passage 48 may include a wastegate 26 for redirecting exhaust gas from the turbine 62. In some embodiments, the wastegate 26 may be a multi-stage wastegate, such as a two-stage wastegate with a first stage configured to control boost pressure and a second stage configured to increase heat flow to the emissions control device 78. The wastegate 26 may be actuated with an actuator 150, which is, for example, an electric actuator. In some embodiments, the actuator 150 may be an electric motor that may be controlled by the controller 12 to adjust a position of a wastegate. Additional details regarding the wastegate 26 and the actuator 150 are described below with respect to Fig. 2 is explained in more detail.

[0025] The intake passage 42 may include a compressor bypass valve 27 configured to redirect intake air around the compressor 60. The wastegate 26 and / or the compressor bypass valve 27 may be controlled by the controller 12 via actuators (e.g., actuator 150) to open when, for example, a lower boost pressure is desired.

[0026] Intake passage 42 may further include a charge air cooler (CAC) 80 (e.g., an intercooler) for reducing the temperature of turbocharged or supercharged intake gases. In some embodiments, charge air cooler 80 may be an air-to-liquid heat exchanger. In other embodiments, charge air cooler 80 may be an air-to-liquid heat exchanger.

[0027] Further, in the disclosed embodiments, an exhaust gas recirculation (EGR) system may direct a desired portion of exhaust gas from the exhaust passage 48 via the EGR passage 140 to the intake passage 42. The amount of EGR provided to the intake passage 42 may be varied by the controller 12 via the EGR valve 142. Further, an EGR sensor may be disposed in the EGR passage and provide an indication of one or more of pressure, temperature, and exhaust gas concentration. Alternatively, the EGR may be controlled using a calculated value based on signals from the MAF (upstream), MAP (intake manifold), MAT (manifold gas temperature), and crankshaft speed sensors. Further, the EGR may be controlled based on an exhaust O 2 sensor and / or an intake oxygen sensor (intake manifold). Under certain conditions, the EGR system can be used to regulate the temperature of the air-fuel mixture in the combustion chamber. Fig. 1 illustrates a high-pressure EGR system, where the EGR is routed from upstream of a turbocharger turbine to downstream of a turbocharger compressor. In other embodiments, the engine may additionally or alternatively include a low-pressure EGR system, where the EGR is routed from downstream of a turbocharger turbine to upstream of a turbocharger compressor.

[0028] Fig. Figure 2 illustrates an electrically actuated wastegate 200 that may be implemented in a turbocharger according to an embodiment of the present disclosure. For example, wastegate 200 may be implemented as wastegate 26, which in Fig. 1. The wastegate 200 may include a wastegate valve 202 actuated by a wastegate actuator 204 via a plurality of links 206. In the illustrated embodiment, the wastegate 200 is an electric wastegate, and the wastegate actuator 204 includes an electric motor 214. The electric motor 214 transmits a driving force to the wastegate valve 202 via the plurality of links 206 to move the wastegate valve between a fully closed position and a fully open position (e.g., end-of-stroke positions), and any position therebetween. When the wastegate 202 is in the fully closed position, the wastegate valve 202 may align with a valve seat 210 to substantially prevent exhaust gas from flowing through the wastegate 200.On the other hand, wastegate 200 includes a vent 208 that can receive and expel gas from exhaust manifold 212 when wastegate 202 is not in the fully closed position such that the wastegate is aligned with the valve seat. In this way, the amount of boost delivered to an engine can be controlled, at least in part, by driving wastegate 202 via electric actuator 214, thereby changing the position of wastegate 202 and the amount of gas arriving at the intake manifold.

[0029] The wastegate actuator 204 may include the electric motor 214 and an output gear 216 that transmits power from the electric motor 214 to the plurality of links 206. The plurality of links 206 may allow the wastegate actuator 204 to be located away from the wastegate valve 202 and the exhaust manifold 212 so that the wastegate actuator may be exposed to less heat than the wastegate valve. The plurality of links may appropriately transmit power output from the electric motor to adjust a position of the wastegate valve. By positioning the wastegate actuator away from the exhaust manifold, the likelihood of degradation due to heat exposure may be reduced.

[0030] In some embodiments, wastegate 200 may further include a bias. The bias may be selected to provide a closing force that maintains wastegate 202 in a fully closed position up to a threshold pressure. The current supplied to a wastegate actuator may be selected to accommodate the closing force of a bias, such as a spring. It will be appreciated that various suitable structures may be used to provide bias or additional closing force to wastegate 202. In the case where a spring is employed, the spring rate may be selected to provide a closing force up to a certain threshold pressure and provide sufficient boost to an engine.

[0031] A wastegate position sensor 218 may be coupled to the wastegate actuator 204 to provide an indication of a position of the wastegate valve 202. For example, the position sensor 218 may measure a rotation angle of the output gear 216 of the electric motor 214 corresponding to a position of the wastegate valve 202. More specifically, the electric motor 214 may have a rotational range corresponding to an operating range of the wastegate valve 202. The position sensor 218 may provide an indication of a wastegate position to a controller 220.

[0032] Controller 220 may be configured to control operation of electric motor 214 to adjust a position of wastegate 202 to control a boost level provided by a turbocharger of an engine. In one example, controller 220 corresponds to controller 12 shown in Fig. 1. More specifically, the controller 220 may be configured to adjust a position of a wastegate valve 202 based on feedback from the position sensor 218 relative to a particular end-stop position of the wastegate valve.

[0033] In one example, the controller 220 may be configured to execute an end-stop detection routine to determine end-stop positions of the wastegate 202. More specifically, the controller 220 may be configured to command, via control of the electric motor 214, a full stroke of the wastegate 202 from a fully open position to a fully closed position to determine a corresponding end-stop position at each end of the stroke. When the wastegate 202 is commanded to complete the stroke, the following conditions are checked: It is determined whether a difference between a wastegate feedback position signal and a commanded position signal is above a predetermined threshold while the signals are in a steady-state condition (e.g.,the signals indicate that the wastegate is at an end of stroke); a speed of the wastegate actuator 204 is determined to be below a predetermined threshold (e.g., substantially zero); and a current signal corresponding to the commanded position is between two predetermined thresholds. For example, under other conditions, a higher value may indicate that an end-stop position has been reached. The lower value may indicate a minimum value at which the wastegate 200 is fully closed such that the wastegate 202 is aligned with the associated structure of the valve seat 210.If all of these conditions are met, then the wastegate may be determined to be at an end-stop position, and the controller 220 may set the position sensor voltage measurements during the end-stop detection interval to a voltage corresponding to the respective end-stop position.

[0034] In some embodiments, during the end stop detection interval, the position sensor signal measurements (other than the commanded position signal) may be filtered to obtain an average based on an integral over interval calculation for the predetermined time interval, which may provide a voltage for the respective end stop position.

[0035] Controller 220 may be configured to repeat the position sensor calibration sequence throughout operation to maintain wastegate accuracy under changing operating conditions. For example, calibration may be performed frequently because the wastegate may be exposed to high temperatures within the turbocharger, which may affect the accuracy of the position sensor output. Additionally, the wastegate electric motor may generate heat, which may affect the accuracy of the position sensor.

[0036] In some embodiments, controller 220 may be configured to execute the position sensor calibration routine at a specific time interval. In some embodiments, controller 220 may be configured to execute the position sensor calibration routine under conditions where commanding full wastegate lift does not disrupt turbocharger operation. Because the position sensor calibration routine may be particularly disruptive to turbocharger operation, it may be desirable to execute the routine under conditions where disrupting turbocharger operation does not impact vehicle drivability. For example, controller 220 may be configured to execute the wastegate position sensor calibration routine under engine idle conditions.More specifically, the calibration routine may be executed under engine idle conditions when there is no indication of a vehicle operator input of vehicle acceleration that would increase a turbocharger pressure level. In one example, the calibration routine may be executed under idle conditions during engine start-up.

[0037] In another example, the calibration routine may be executed under deceleration fuel shut-off (DFSO) conditions. For example, DFSO conditions may occur while the vehicle is idling, with fuel injection turned off, the throttle closed, and the engine running faster than idle. DFSO conditions may occur at various engine speeds. The calibration routine may be executed under DFSO conditions because there is no imminent use for turbocharger pressure as the vehicle is decelerating. Accordingly, opening the wastegate to execute the calibration routine may not disrupt the vehicle's drivability under DFSO conditions.

[0038] It will be appreciated that the controller 220 may be configured to detect any suitable condition that does not disrupt vehicle drivability when executing the calibration routine without departing from the scope of the present disclosure.

[0039] It will be appreciated that various suitable wastegate arrangements may be used without departing from the scope of the present disclosure and may depend, for example, on mechanical design and packaging requirements.

[0040] The configurations presented above enable various methods for detecting end-stop positions of a wastegate and calibrating a position sensor based on detected end-stop positions. Accordingly, some such methods are described below by way of example and with further reference to the above-mentioned configurations. However, it will be understood that these and other methods, fully within the scope of the present disclosure, may also be provided by other configurations.

[0041] Fig. 3 illustrates a method 300 for detecting an end stop position of an electrically actuated wastegate according to an embodiment of the present disclosure. For example, the method may be performed by the controller 12 Fig. 1 or the control 220 Fig. 2. At 302, method 300 may include determining operating conditions. For example, determining operating conditions may include receiving sensor signals indicative of operating parameters of the vehicle and calculating or deriving various operating parameters. Further, determining operating conditions may include determining the state of components and actuators of the vehicle. In one example, operating parameters that may be determined include engine speed, turbocharger pressure, wastegate position (e.g., voltage), wastegate actuator speed, etc.

[0042] At 304, method 300 may include commanding a wastegate to a full-stop position. For example, the command may be performed by controlling an electric motor coupled to the wastegate. In a particular example, commanding includes commanding a full stroke of the wastegate from a fully open position to a fully closed position.

[0043] At 306, method 300 may include determining whether a difference between a wastegate command signal and a feedback position signal is greater than a predetermined threshold while the signals are in a steady-state condition. For example, the feedback position signal may be provided by a position sensor, such as sensor 218, included in Fig. 2. The determination may be made to verify that the wastegate has actually moved to the commanded position. If the difference between the command signal and the feedback position signal is greater than the predetermined threshold while the signals are in a steady-state condition, then method 300 proceeds to 308. Otherwise, method 300 returns to other operations.

[0044] At 308, method 300 may include determining whether a speed of the wastegate actuator is less than a speed threshold. For example, the speed threshold may be substantially zero or only slightly greater than zero. In one example, the determined speed may be that of the electric motor 214 operating in Fig. 2. The determination may be made to check whether the wastegate actuator is in a stationary position. If the wastegate actuator speed is less than the speed threshold, then method 300 proceeds to 310. Otherwise, method 300 returns to other operations.

[0045] If all conditions are met at 310, then the wastegate is determined to be at the end-stop position, and the position sensor feedback signal is associated with the end-stop position. In some embodiments, during the time at the end-stop position, all feedback signals may be filtered to obtain an average based on an integral-over-interval calculation for the test period or predetermined time interval. The average of the sensor measurements during this time provides a sensor signal level (e.g., voltage) associated with that particular end-stop position.

[0046] After the end-stop position is determined, the process may be repeated to determine the other end-stop position. More specifically, the wastegate may be commanded to move to the other end-stop position, and the sequences may be repeated, whereby, after determining that the wastegate is at the other end-stop position, the position sensor measurement may be associated with a new position sensor signal for the other end-stop position. This end-stop detection routine may be executed at predetermined time intervals. The time spent at each end-stop position (e.g., upper and lower) may be adjustable.

[0047] The above method may be performed to determine an end-stop position of a wastegate. The determined end-stop position may be used in the position sensor calibration strategy described herein.

[0048] Fig. 4 illustrates a method 400 for calibrating a position sensor based on detected end stop positions of a wastegate according to an embodiment of the present disclosure. For example, the method may be performed by the controller 12 Fig. 1 or the control 220 Fig. 2. At 402, method 400 may include determining operating conditions.

[0049] At 404, method 400 may include determining whether operating conditions are suitable for performing end-of-stroke detection and position sensor calibration. As discussed above, the end-of-stroke detection routine may be an intrusive operation under certain conditions because full wastegate lift is commanded to determine the end-of-stroke positions at each end of the stroke. Accordingly, it may be determined whether operating conditions are suitable for commanding full wastegate lift without disturbing or minimally disturbing vehicle drivability.

[0050] For example, suitable operating conditions may include engine idle conditions. More specifically, the calibration routine may be executed under engine idle conditions when there is no indication of vehicle acceleration from a vehicle operator input that would increase a turbocharger pressure level. In one example, the calibration routine may be executed under idle conditions at engine start-up. In another example, the calibration routine may be executed under conditions where the wastegate is open to decrease a turbocharger pressure level. In another example, the calibration routine may be executed under deceleration fuel shut-off (DFSO) conditions.It will be appreciated that any suitable condition that does not interfere with vehicle drivability during execution of the calibration routine may be determined without departing from the scope of the present disclosure. If it is determined that operating conditions are suitable for performing a position sensor calibration, then method 400 proceeds to 406. Otherwise, method 400 returns to other operations.

[0051] At 406, method 400 may include commanding the wastegate to a fully open position.

[0052] At 408, method 400 may include executing an end-stop detection routine to determine a fully open end-stop position of the wastegate. The end-stop position may be associated with a position sensor signal voltage as a result of executing the end-stop detection routine. For example, the end-stop detection routine that may be executed may include method 300 described in Fig. 3 is shown.

[0053] At 410, method 400 may include commanding the wastegate to a fully closed position. In other words, a full lift of the wastegate may be performed.

[0054] At 412, method 400 may include executing an end-stop detection routine to determine a fully closed end-stop position of the wastegate. The end-stop position may be associated with a position sensor signal voltage as a result of executing the end-stop detection routine. For example, the end-stop detection routine that may be executed may include method 300 described in Fig. 3. It will be appreciated that the order in which the end stop positions are detected may be changed without departing from the scope of the present disclosure.

[0055] At 414, method 400 may include determining a wastegate position sensor gain based on the determined end-stop positions. More specifically, both end-stop position sensor voltage measurements may be used to calculate a new sensor gain for adjusting the wastegate between the end-stop positions.

[0056] In some embodiments, the sensor calibration sequence may be repeated at predetermined time intervals to maintain the calibration of the wastegate position sensor. In some embodiments, the sensor calibration sequence may be repeated when changes in operating temperature sufficiently affect the physical properties of the wastegate components. Accordingly, accurate wastegate control may be maintained throughout vehicle operation, even when wastegate components undergo physical changes due to changing operating conditions (e.g., expansion of connectors due to heat exposure).

[0057] It will be understood that the exemplary control and estimation routines disclosed herein may be used with various system configurations. These routines may represent one or more different processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, the disclosed method steps (operations, functions, and / or actions) may represent code to be programmed into the computer-readable storage medium in an electronic control system.

[0058] It will be understood that some of the method steps described and / or illustrated herein may be omitted in some embodiments without departing from the scope of this disclosure. Likewise, the specified order of method steps may not always be required to achieve the intended results, but is provided for ease of illustration and description. One or more of the illustrated actions, functions, or operations may be performed repeatedly depending on the particular strategy employed.

[0059] Finally, it will be understood that the subject matter, systems, and methods described herein are exemplary, and that these specific embodiments or examples are not to be considered limiting, as numerous variations thereof are contemplated. Accordingly, the present disclosure encompasses all novel and non-obvious combinations and sub-combinations of the various systems and methods disclosed herein, as well as all equivalents thereof.

Claims

[1] Method comprising: during the calibration of a wastegate position sensor (218): Setting a boost pressure control valve (202) to a first end stop position; Associating a first feedback position with the first end stop position; Setting the boost pressure control valve (202) to a second end stop position; Associating a second feedback position with the second end stop position; and Setting a position sensor gain based on the first feedback position and the second feedback position. [2] The method of claim 1, wherein the first end stop position is a position at which the wastegate (202) aligns with a valve seat (210) to substantially stop exhaust flow. [3] The method of claim 1, wherein the second end stop position is a fully open position of the boost pressure control flap (200). [4] The method of claim 1, wherein the first feedback position is associated with the first end stop position in response to a difference between a feedback position signal of the wastegate position sensor (218) and a commanded position signal being greater than a difference threshold while the feedback position signal and the commanded position signal are in a steady state and a speed of an electric actuator (150) is less than a speed threshold. [5] The method of claim 1, wherein the second feedback position is associated with the second end stop position in response to a difference between a feedback position signal of the wastegate position sensor and a commanded position signal being greater than a difference threshold while the feedback position signal and the commanded position signal are in a steady state and a speed of an electric actuator (150) is less than a speed threshold. [6] The method of claim 1, wherein associating the first feedback position signal with the first endstop position includes determining an average of wastegate position sensor signal measurements during a test period in which the wastegate is at the first endstop position and associating the average with the first endstop position. [7] The method of claim 1, wherein associating the second feedback position signal with the second endstop position includes determining an average of wastegate position sensor signal measurements during a test period in which the wastegate (202) is at the second endstop position and associating the average with the second endstop position. [8] The method of claim 1, wherein the calibration of the wastegate position sensor (218) is performed during a calibration operating condition. [9] The method of claim 8, wherein the calibration operating condition includes an engine idle condition. [10] The method of claim 8, wherein the calibration operating condition includes a fuel cut-off condition. [11] A method for calibrating a wastegate position sensor (218), comprising: during a calibration operating condition, Controlling an electric actuator (150) to set a wastegate valve (202) to a first end stop position; Associating a first feedback position signal of the wastegate position sensor (218) with the first end stop position; Controlling the electric actuator (150) to set the wastegate valve (202) to a second end stop position; Associating a second feedback position signal of the wastegate position sensor (218) with the second end stop position; and Adjusting a wastegate position sensor gain based on the first feedback position signal and the second feedback position signal. [12] The method of claim 11, wherein the calibration operating condition includes an engine operating condition in which a full lift of the wastegate (202) is commanded to control a turbocharger pressure. [13] The method of claim 11, wherein the calibration operating condition includes an engine idle condition. [14] The method of claim 11, wherein the calibration operating condition includes a fuel cut-off condition. [15] The method of claim 11, wherein the first end stop position is a fully closed position and the second end stop position is a fully open position. [16] The method of claim 11, wherein associating a first feedback position signal includes determining a first average of position sensor signal measurements during a test period in which the wastegate (202) is at the first end-stop position and associating the first average with the first end-stop position, and associating a second feedback position signal includes determining a second average of position sensor signal measurements during a test period in which the wastegate (202) is at the second end-stop position and associating the second average with the second end-stop position. [17] Method comprising: Controlling an electric actuator (150) to set a wastegate valve (202) to a first end stop position; when a difference between a first feedback position signal and a first commanded position signal is greater than a difference threshold while the first feedback position signal and the first commanded position signal are in a steady state and a speed of an electrical actuator (150) is less than a speed threshold, associating the first feedback position signal with the first end stop position. [18] The method of claim 17, wherein associating the first feedback position signal includes determining an average of wastegate position sensor signal measurements during a test period in which the wastegate (202) is at the first endstop position and associating the average with the first endstop position. [19] The method of claim 17, further comprising: Controlling the electric actuator (150) to set a wastegate valve (202) to a second end stop position; when a difference between a second feedback position signal and a second commanded position signal is greater than the difference threshold while the second feedback position signal and the second commanded position signal are in a steady state and a speed of an electric actuator (150) is less than the speed threshold, Associating the second feedback position signal with the second end stop position; and Adjusting a wastegate position sensor gain based on the first feedback position signal and the second feedback position signal. [20] The method of claim 19, wherein associating the second feedback position signal includes determining an average of wastegate position sensor signal measurements during a test period in which the wastegate (202) is at the second endstop position and associating the average with the second endstop position.

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