Method and system for deriving throttle intake pressure

Abstract

A method for an engine (10) having a throttle (62), comprising: if a derived throttle inlet pressure (TIP) value differs from a measured TIP value, adjusting a wastegate (72) of a turbocharger based on the derived TIP value and not based on the measured TIP value, wherein the derived TIP value is based on an air flow through the throttle (62), a throttle angle, and an intake manifold absolute pressure (MAP).

Description

Area

[0001] The present disclosure relates to a turbocharged engine system. Background and brief presentation

[0002] Turbocharging an engine allows it to produce similar power to a larger-displacement engine while maintaining engine pumping work approximately equal to that of a naturally aspirated engine of similar displacement. Turbocharging can thus expand an engine's operating range. Turbochargers work by compressing intake air via a compressor driven by a turbine driven by the exhaust gas flow. The amount of compression provided by the turbocharger (known as boost pressure) can be regulated by adjusting the position of a wastegate coupled to the turbine based on feedback from a throttle inlet pressure sensor (TIP sensor) located upstream of the throttle inlet and downstream of the compressor.

[0003] Document DE 40 32 451 A1 discloses a device for boost pressure control. Document DE 100 21 639 C1 describes a method for diagnosing the ambient pressure for internal combustion engines. Document DE 10 2007 052 ​​576 A1 discloses a diagnostic method for detecting errors in a pressure sensor-supported boost pressure control of an exhaust gas turbocharger of an internal combustion engine. Document DE 10 2006 008 493 A1 describes a method and device for controlling an internal combustion engine. Document DE 10 2008 005 958 A1 discloses a method and device for identifying a faulty pressure sensor in an intake tract of an internal combustion engine.

[0004] If the throttle inlet pressure sensor is malfunctioning, for example, if the throttle inlet pressure sensor is stuck in certain areas and outputs a constant signal even with changing throttle inlet pressure, the engine boost control program may continue to adjust the wastegate position even after the target boost pressure has been reached. Under certain conditions, this can lead to engine knock and / or engine damage if the wastegate is moved further toward a more closed position than indicated, thus compressing the intake air more than desired.

[0005] Here, the inventors recognized that with standard throttle inlet pressure sensor diagnostics, a relatively long time may elapse before a degradation of the throttle inlet pressure sensor is detected. While the diagnostic program is running, excessive boost pressure conditions may occur, leading to engine knock and / or engine damage. Accordingly, a method is provided that at least partially mitigates the problems of the above approach. In one embodiment, a method for a throttled engine includes, if an inferred throttle inlet pressure (TIP) deviates from a measured TIP value, adjusting a wastegate of a turbocharger based on the inferred TIP value rather than the measured TIP value, wherein the inferred TIP value is based on airflow through the throttle, throttle angle, and manifold absolute pressure (MAP).

[0006] In this way, a derived TIP value can be estimated based on engine operating parameters other than the actual throttle inlet pressure. If the values ​​differ, the measured TIP value can be replaced with the derived TIP value until the TIP sensor diagnostic program detects a degraded TIP sensor. This can prevent engine knock and / or engine damage that may occur before the diagnostic program detects a degraded TIP sensor.

[0007] The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description, considered alone or in conjunction with the accompanying drawings.

[0008] It should be understood that the above summary is intended to introduce, in a simplified form, a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is clearly defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages noted above or in any other part of this disclosure. Brief description of the drawings Fig. 1 shows a schematic representation of an engine. Fig. 2 shows a flow chart of a problem-oriented method for boost pressure control based on the throttle inlet pressure. Fig. 3A-3B show a flowchart for a method for deriving a throttle inlet pressure value. Detailed description

[0009] Engine systems contain a multitude of sensors that collect data related to engine operating parameters, and the sensor outputs can be used by the engine control system to maintain desired engine operation. To ensure that the sensors are functioning, various diagnostic programs and / or rationality checks can be periodically performed on the sensors. However, such programs can be time-consuming and / or may be designed to run only during specific operating conditions. Thus, if a sensor is indeed degraded, the time elapsed before and during the execution of the diagnostic program can lead to disruption of engine control strategies. In some cases, for example, if a throttle inlet pressure (TIP) sensor is degraded, the loss of boost control can lead to engine combustion problems, such as knocking, and possibly engine damage.

[0010] According to the presently disclosed embodiments, throttle inlet pressure may be continuously derived based on operating parameters, including MAP, throttle angle, and airflow through the throttle. Under some circumstances, such as when the derived TIP value is outside a threshold range of the TIP value measured by the TIP sensor, the measured TIP value may be replaced by the derived TIP value. Therefore, during the runtime of the TIP sensor diagnostic program, the engine's boost control strategy may be maintained using the derived TIP value. Fig. 1 shows an engine with a turbocharger, TIP sensor and control unit. The control unit can be configured to Fig. 2-3B.

[0011] With reference specifically to Fig. 1, it contains a schematic representation of a cylinder of a multi-cylinder internal combustion engine 10. The engine 10 may be controlled at least in part by a control system including a controller 12 and by inputs 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.

[0012] The combustion cylinder 30 of the engine 10 may include combustion cylinder walls 32 with a piston 36 positioned within them. The piston 36 may be coupled to the crankshaft 40 such that the reciprocating motion of the piston is translated into a rotational motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate gear system. Furthermore, a starter motor may be coupled to the crankshaft 40 via a flywheel to enable a starting operation of the engine 10.

[0013] Combustion cylinder 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 passage 48 may each selectively communicate with combustion cylinder 30 via an intake valve 52 and exhaust valve 54. In some embodiments, combustion cylinder 30 may include two or more intake valves and / or two or more exhaust valves.

[0014] In this example, intake valve 52 and exhaust valve 54 may each be controlled via cam actuation via the respective cam actuation system 51 and 53, respectively. Cam actuation systems 51 and 53 may each include one or more cams and may utilize one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems operable by controller 12 to vary valve operation. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In alternative embodiments, intake valve 52 and / or exhaust valve 54 may be controlled via electrical valve actuation.For example, cylinder 30 may alternatively include an intake valve controlled via electrical actuation and an exhaust valve controlled via cam actuation, including CPS and / or VCT systems.

[0015] The fuel injector 66 is shown directly coupled to the combustion cylinder 30 for injecting fuel therein proportional to the pulse width of the FPW (fuel pulse width) signal received from the control unit 12 via the electronic driver 68. In this way, the fuel injector 66 provides what is known as direct injection of fuel into the combustion cylinder 30. The fuel injector may, for example, be mounted on the side of the combustion cylinder or in the top of the combustion cylinder. The fuel may be supplied to the fuel injector 66 from a fuel supply system (not shown) that includes a fuel tank, a fuel pump, and a fuel rail.In some embodiments, the combustion cylinder 30 may alternatively or additionally include a fuel injector disposed in an intake port 42 in a configuration that provides so-called port injection in the intake port upstream of the combustion cylinder 30.

[0016] The intake passage 42 may include a throttle 62 with a throttle plate 64. In this particular example, the position of the throttle plate 64 may be varied by the controller 12 via a signal provided to an electric motor or actuator included in the throttle 62, which configuration may be referred to as electronic throttle control (ETC). In this manner, the throttle 62 may be operated to vary the intake air provided to the combustion cylinder 30, among other combustion cylinders. The intake passage 42 may include a mass air flow sensor 120 and an intake manifold pressure sensor 121 for providing respective MAF and MAP signals to the controller 12.

[0017] The ignition system 88 may provide an ignition spark to the combustion chamber 30 via the spark plug 92 in response to a spark advance signal SA from the controller 12 under select operating modes. While spark-ignition components are shown, in some embodiments, the combustion chamber 30 or one or more combustion chambers of the engine 10 may be operated in a self-ignition mode, with or without a spark.

[0018] In the illustration, an exhaust gas sensor 126 is coupled to the exhaust passage 48 downstream of the catalyst 70. The sensor 126 may be any suitable sensor for providing an indication of the exhaust air / fuel ratio, such as a linear oxygen sensor or universal or wide-range exhaust gas oxygen (UEGO), a bistable oxygen sensor (two-state oxygen sensor, EGO), a heated oxygen sensor (HEGO), a NOx -, HC, or CO sensor. The exhaust system may include light-off catalysts and underbody catalysts, as well as exhaust manifold, upstream, and / or downstream air-fuel ratio sensors. In one example, the catalyst 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each including multiple bricks, may be used. In one example, the catalyst 70 may be a three-way catalyst.

[0019] The control unit 12 is in Fig. 1 as a microcomputer, comprising a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, which in this particular example is shown as a read-only memory chip 106, a working memory 108, keep-alive memory 110 and a data bus.The controller 12 may receive various other signals and information from sensors coupled to the engine 10 in addition to the signals previously discussed, including measurements of the mass airflow (MAF) from a mass airflow sensor 120; engine coolant temperature (ECT) from a temperature sensor 112 coupled to the cooling sleeve 114; a profile ignition pickup (PIP) signal from a Hall sensor 118 (or other type) coupled to the crankshaft 40; throttle position (TP) from a throttle position sensor 58; an intake manifold absolute pressure (MAP) signal from a sensor 121 and throttle inlet pressure (TIP) from a sensor 122. Since the sensor 122 is located downstream of a compressor (as explained below), it can be used to determine the boost pressure provided by the turbocharger.The manifold pressure (MAP) signal from a manifold pressure sensor may be used to provide an indication of vacuum, or pressure, within the intake manifold 44. Note that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. In 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) admitted to the cylinder. In one example, sensor 118, which is also utilized as an engine speed sensor, may produce a predetermined number of evenly spaced pulses during each revolution of the crankshaft 40.In some examples, the read-only memory 106 storage medium may be programmed with computer-readable data representing instructions executable by the processor 102 for performing the methods described below and other variations expected but not specifically listed.

[0020] The engine 10 may further include a compression device, such as a turbocharger or supercharger having at least one compressor 162 arranged along the intake passage 42. For a turbocharger, the compressor 162 may be at least partially driven by a turbine 164, for example, via a shaft 161 or other coupling arrangement. The turbine 164 may be arranged along an exhaust passage 48. Various arrangements may be provided for driving the compressor. For a supercharger, the compressor 162 may be at least partially driven by the engine and / or an electric machine and may not include a turbine. The amount of compression provided to one or more cylinders of the engine via a turbocharger or supercharger may thus be varied by the controller 12.For example, in some cases, the turbine 164 may drive an electric generator to provide power to the battery via a turbo driver. Energy from the battery may then be used to drive the compressor 162 via a motor. Additionally, in some embodiments, the turbocharger may be a variable-geometry turbocharger.

[0021] Furthermore, the exhaust passage 48 may include a wastegate 72 for directing exhaust gas away from the turbine 164. Furthermore, the intake passage 42 may include a compressor bypass valve 158 configured to bypass intake air around the compressor 162. The wastegate 72 and / or the compressor bypass valve (CBV) 158 may be controlled by the controller 12 to open when, for example, a lower boost pressure is desired. The amount of compression (e.g., boost pressure) provided to one or more cylinders of the engine via a turbocharger or supercharger may thus be varied by the controller 12 based on feedback from various sensors, such as the TIP sensor 122.

[0022] As previously explained, the position of the wastegate 72 may be controlled to provide a desired amount of boost pressure to the engine. The boost pressure may be measured by the TIP sensor 122. The wastegate position 72 may thus be adjusted based on feedback from the TIP sensor 122. In one example, if an increase in boost pressure is desired, the wastegate 72 may be adjusted to a more closed position until the boost pressure downstream of the compressor 162 is a desired boost pressure indicated based on feedback from the TIP sensor 122. However, if the TIP sensor 122 is degraded, it may provide inaccurate indications of the actual boost pressure upstream of the throttle 62. As such, the wastegate 72 may be moved further to the more closed position, thereby increasing the boost pressure.This can cause an excessive boost pressure condition, which could lead to, for example, engine knock or engine damage. To protect the engine from excessive boost pressure resulting from a malfunctioning TIP sensor, a rationality check or diagnostic program can be performed to verify that the TIP sensor is functioning as intended. For example, a diagnostic program may include commanding the wastegate to change its position to effect a change in throttle inlet pressure and monitoring the TIP sensor output signal to ensure that it changes in accordance with the requested change in wastegate position.If the diagnostic program indicates a degradation of the TIP sensor, the turbocharger operation may be temporarily suspended or the boost pressure may be adjusted based on feedback from a sensor other than the TIP sensor, such as the MAP sensor, turbine pressure decrease, etc., until the TIP sensor is serviced.

[0023] However, completing such a program can take a relatively long time (e.g., five seconds). If, while the diagnostic program is running, the engine boost control strategy continues to rely on feedback from the TIP sensor to make adjustments to achieve a desired boost level, an overboost or underboost condition may occur if the TIP sensor is actually malfunctioning, leading to combustion problems and possibly engine damage. To prevent such problems, the measured TIP value obtained from the TIP sensor can be replaced with a derived TIP value. The derived TIP value can be determined using information already present in the engine control strategy for determining the desired throttle angle, as described below with reference to the Fig. 2-3B is explained in more detail.

[0024] The system for Fig. 1 thus provides a system comprising: an engine, a turbocharger fluidly coupled to the engine; a wastegate coupled to a turbine; a throttle upstream of the engine and controlling airflow to the engine; and a controller storing non-transitory instructions executable to: set an initial position of the wastegate based on feedback from a throttle inlet pressure (TIP) sensor upstream of the throttle; calculate a derived TIP value and compare it to a measured TIP value from the TIP sensor; and if the derived TIP value differs from the measured TIP value, adjust a subsequent position of the wastegate based on the derived TIP value.

[0025] The derived TIP value can be calculated based on a throttle model that estimates TIP from throttle angle, airflow through the throttle, and intake manifold absolute pressure. Airflow through the throttle can be calculated based on a rate of change of intake manifold absolute pressure.

[0026] Fig. 2 shows a flowchart of a method 200 for adjusting a wastegate position based on a throttle inlet pressure (TIP) value. The method 200 may be executed by an engine control unit according to non-transitory instructions stored therein. The method 200 may be implemented with components of an engine system, such as the system of Fig. 1 with the control unit 12, the wastegate 72 and the TIP sensor 122.

[0027] At 202, method 200 includes determining engine operating parameters. The determined operating parameters may include, but are not limited to, throttle inlet pressure (determined by TIP sensor 122), MAP determined by MAP sensor 121, throttle angle, engine speed and load, desired boost pressure, wastegate position, and other parameters. At 204, the throttle inlet pressure is measured based on output values ​​from the TIP sensor. At 206, the wastegate position, if indicated, is adjusted based on the measured TIP to provide the desired boost pressure.

[0028] At 208, the throttle inlet pressure is also derived based on a throttle model that calculates the airflow through the throttle and calculates the calculated airflow along with the MAP and throttle angle to estimate the throttle inlet pressure. Specifically, the lookup tables used by the ECU to calculate the throttle angle from the airflow, throttle inlet pressure, and MAP can be used to calculate the TIP given the known throttle angle, MAP, and airflow. The details of the derivation of the throttle inlet pressure are discussed below with reference to Fig. 3A and Fig. 3B.

[0029] The derivation of the throttle inlet pressure may be performed continuously so that all measured throttle inlet pressure values ​​based on TIP sensor output values ​​can be compared to the derived TIP values, as described in more detail below. However, in some embodiments, the derived TIP value may only be calculated during certain operating periods, such as while the TIP sensor diagnostic / rationality check program is being executed and / or when other collected sensor data indicates that the TIP sensor may be degraded.

[0030] After determining the derived TIP value, method 200 proceeds to 210 to determine whether the derived TIP value is outside a threshold range of the measured TIP value. That is, at a given time, the throttle inlet pressure may be both measured by the TIP sensor and derived using the throttle model. The two TIP values ​​may be compared to determine whether the values ​​differ by more than a threshold amount. The threshold range may be any suitable range. For example, the derived TIP value may be considered equal to the measured value if the derived TIP value is within 5% of the measured value in one example, or within 10% of the measured value in another example. Thus, if the derived TIP value differs from the measured TIP value by more than 5 or 10%, the two values ​​may be considered different.

[0031] If the two values ​​do not differ, that is, if the derived TIP value is within the threshold range of the measured TIP value, method 200 proceeds to 212 to further adjust the wastegate position based on feedback from the TIP sensor, and then method 200 proceeds to 216, as explained below.

[0032] If the two values ​​differ, method 200 proceeds to 214 to adjust the wastegate position based on the derived TIP value (and subsequent derived TIP values) rather than the measured TIP value. At 216, the TIP sensor rationality check / diagnostic routine is performed. During the rationality check period, the derived TIP values ​​are still used for adjustment if it is determined that the derived TIP value differs from the measured TIP value. However, if the measured TIP value and the derived TIP value do not differ, the measured TIP value may be used to control the wastegate position during the rationality check in some embodiments.However, in other embodiments, during the rationality check, even if the measured TIP value and the derived TIP value are the same, the measured TIP values ​​may be replaced by the derived TIP values.

[0033] If the rationality check confirms that the TIP sensor is impaired, the control module may take a predetermined action, including notifying a vehicle operator (via a malfunction indicator lamp), setting a diagnostic code, and / or adjusting the boost control strategy (e.g., by disabling turbocharger operation or by controlling the wastegate position based on other sensor data).

[0034] Thus, according to the method described above, the measured TIP may be replaced by the derived TIP if the TIP values ​​differ from each other by more than a threshold amount, at least during a period up to and during a rationality check. However, in some embodiments, if the derived TIP value and the measured TIP value differ from each other but by less than the threshold amount, the derived TIP value and the measured TIP value may be blended together to generate a blended TIP value, which is then used to control the wastegate position. In one example, if the measured TIP value is significantly lower than the derived TIP value, the derived and measured TIP values ​​may be blended according to a blending factor table that blends the two TIP values ​​depending on the error between the two values. For example, if the error (e.g.If the error (the difference between the derived and measured values) is relatively large, e.g., 10 inHg, mixing of the derived TIP value into the measured value begins. For a sufficiently large error, e.g., 12 inHg, the measured value is completely replaced by the derived TIP value. A hysteresis band can be used to avoid a noisy mixing factor for either a noisy estimate or a noisy sensor reading. Therefore, if the derived TIP value differs from the measured TIP value by more than a threshold amount, it indicates that the sensor is degraded, and a separate rationality check is not necessarily performed.

[0035] If you now turn to the Fig.3A-3B, a method 300 for deriving a throttle inlet pressure based on a throttle model is presented. Method 300 may be performed during execution of method 200 to control the turbocharger wastegate using the derived TIP value at least during the duration of the TIP sensor rationality check.

[0036] At 302, method 300 determines whether MAP is decreasing to barometric pressure (BP). That is, at 302, the method assesses whether MAP is decreasing and whether MAP is close to BP. If so, MAP is most likely decreasing to BP, and method 300 thus proceeds to 304 to set the derived TIP value as the barometric pressure and use a BP filter constant during a filtering step explained below. Method 300 then proceeds to 334, which is described in more detail below.

[0037] If MAP does not drop to BP, method 300 proceeds to 306 to calculate the air flow through the throttle using a manifold charge model. The manifold charge model uses the Ideal Gas Law to show that the rate of change of intake manifold absolute pressure (MAP) is due to the difference between the flow into the manifold (throttle) and out of it (cylinder), as indicated at 308.

[0038] The rate of change of MAP is thus equal to the rate of change of the mass of the airflow through the throttle, multiplied by the temperature and volume of the intake port and the ideal gas constant. Accordingly, assuming that temperature and volume are relatively constant, the pressure change is due to a change in mass. However, if the temperature changes, the temperature change can be accounted for in the model.

[0039] Furthermore, assuming no leak, the mass change is due to the difference between the flow rates into and out of the manifold, and thus dP / dt = (throt_flow - cyl_flow) * RT / V. The equation can be rearranged to: throt_flow = cyl_flow + dP / dt * V / (RT), where V / (RT) is constant, thus the air flow through the throttle depends on the rate of change of MAP.

[0040] After the air flow through the throttle is calculated, a simple search mechanism in the throttle model is used to derive the TIP value. The standard use of the throttle model is to calculate the throttle angle (TA) for a given flow, TIP, and MAP. The model characterization tables in the ECU are configured to support this use. To perform the search mechanism, an assumed value is assigned to TIP, and this value is used in the throttle model to calculate a throttle angle.The calculated throttle angle is compared to the actual instantaneous requested throttle angle, and if the throttle angles differ, the assumed TIP value is adjusted and the throttle angle is recalculated until a TIP value is reached that provides a calculated throttle angle relatively close to the actual throttle angle.

[0041] The assumed initial TIP value can be any TIP value. However, to simplify the search process, the assumed initial TIP value can be a minimum or lowest possible TIP value to provide adjustments to the assumed TIP value in only one direction. For example, the assumed initial TIP value can be set as MAP or BP, since TIP cannot be lower than MAP. Thus, as indicated at 310, the assumed initial TIP is set as the minimum TIP.

[0042] At 312, method 300 includes calculating a predetermined throttle angle based on the minimum TIP, flow through the throttle, and MAP using the throttle model tables stored in the controller. At 314, the predicted throttle angle is compared to the requested throttle angle to determine if the predicted throttle angle is less than or equal to the requested throttle angle. If the predicted TA is less than or equal to the requested TA, method 300 proceeds to 316 to set the derived TIP value equal to the assumed initial TIP and set the time constant to zero. Method 300 then proceeds to 334.If the predicted TA is not less than or equal to the requested TA, method 300 proceeds to 318 to determine whether the predicted TA is greater than the requested TA and whether the assumed TIP is less than a maximum possible TA. The maximum possible TA may be based on the configuration of the engine and turbocharger and / or operating parameters such as engine speed and engine load. If the assumed TIP is not less than the maximum TIP, method 300 proceeds to 322, as described below.

[0043] If the predicted TA is greater than the requested TA and the assumed TIP is less than the maximum, method 300 proceeds to 320 to increment the assumed TIP and recalculate the throttle angle based on the incremented TIP, throttle airflow, and MAP. The assumed TIP may be incremented by a suitable amount. In one example, the assumed TIP may be incremented by a fixed amount, such as 1 kPa. In another example, the assumed TIP may be incremented by an amount that varies depending on engine speed.For example, when the engine speed is high, the assumed TIP may be incremented by a larger amount than when the engine speed is low, to minimize the processing power used to perform calculations at higher engine speeds, for example, where the processor performs more calculations at a higher speed. Additionally or alternatively, the assumed TIP may be incremented by an amount based on processor idle time, number of injections, or another suitable factor that indicates how heavily the processor is being used or how precise the desired result should be.

[0044] After the TA is recalculated, method 300 loops back to 318 to again determine whether the predicted TA is greater than the requested TA. The incrementing of the assumed TIP and recalculation of the throttle angle may be repeated until the predicted TA is no longer greater than the requested TA, at which time method 300 then proceeds to 322.

[0045] At 322, it is determined whether the assumed TIP is greater than or equal to the maximum TIP. If so, then method 300 proceeds to 324 to set the derived TIP as the maximum TIP, and method 300 proceeds to 334. If the assumed TIP (that is, the assumed TIP that provided a predicted throttle angle less than or equal to the actual throttle angle according to the above determination) is less than the maximum TIP, method 300 proceeds to 326 to interpolate the derived TIP value as a value between the two previously assumed TIP values. As a best coding practice, this calculation has a divide-by-zero safeguard that holds the last value when the denominator in an equation is zero. At 328, it is determined whether the derived TIP is increasing or decreasing by observing the change in the derived TIP from previously derived TIPs.If the derived TIP is increasing, method 300 proceeds to 330 to use the time constant for increasing TIP, whereas if the derived TIP is not increasing, method 300 proceeds to 332 to use the time constant for decreasing TIP. Both 330 and 332, as well as 324, 316, and 304, proceed to 334, where, if indicated, the derived TIP is filtered based on the determined time constant. By using increasing or decreasing time constants, the difference between fill / empty aspects of boost buildup and decay can be modeled. In doing so, an accurate match between actual performance and modeled performance can be achieved. Method 300 then loops back.

[0046] Method 300 thus provides for deriving a throttle inlet pressure using a throttle model. The throttle model is typically configured to calculate the throttle angle given the measured TIP, MAP, and calculated throttle airflow. By starting with an assumed initial TIP value, the model can be used to calculate a predicted throttle angle, which is compared to the actual throttle angle requested by the controller. If the predicted and requested throttle angles differ, the assumed initial TIP is adjusted (i.e., incremented) until an assumed TIP value is found that provides a predicted TA equal to the requested TA. This assumed TIP is then set as the derived TIP.If the final incremented TIP provides a forecasted TA that is less than the requested TA (that is, if the TIP is incremented from a first TIP that provides a forecasted TA that is greater than the requested TA to a second TIP that provides a forecasted TA that is less than the requested TA), a TIP value between the first TIP and the second TIP may be used as the derived TIP.

[0047] The derived TIP can be compared with the measured TIP. If the two TIP values ​​differ, the measured TIP value can be substituted for the derived TIP value, at least until a rationality check or diagnostic program is performed on the TIP sensor to ensure that the TIP sensor is not impaired. This way, internal combustion engine failures can be avoided if the TIP sensor is impaired while the TIP sensor diagnostic program is being performed.

[0048] In one embodiment, a method for a throttled engine includes, if an inferred throttle inlet pressure (TIP) differs from a measured TIP value, adjusting a wastegate of a turbocharger based on the inferred TIP value and not based on the measured TIP value, where the inferred TIP value is based on airflow through the throttle, throttle angle, and manifold absolute pressure (MAP).

[0049] The method may further include determining the measured TIP value based on an output value from a TIP sensor upstream of the throttle. If the derived TIP value differs from the measured TIP value, the method may further include performing a sensor rationality check on the TIP sensor. If the sensor rationality check confirms TIP sensor degradation, the wastegate may continue to be adjusted based on subsequent derived TIP values. If the sensor rationality check does not confirm TIP sensor degradation, the wastegate may be adjusted based on subsequent measured TIP values.

[0050] The flow through the throttle may be determined based on a cylinder filling model that determines the flow through the throttle based on a change in MAP. Deriving the TIP value may include: setting a first assumed TIP value equal to MAP; calculating the throttle angle based on the first assumed TIP value, the flow through the throttle, and the MAP; comparing the calculated throttle angle to a requested throttle angle; and if the calculated throttle angle is less than or equal to the requested throttle angle, setting the first assumed TIP value as the derived TIP value.If the calculated throttle angle is greater than the requested throttle angle, deriving the TIP value may include incrementing the first assumed TIP value and recalculating the throttle angle until the first assumed TIP value is incremented to a second assumed TIP value that results in the calculated throttle angle being less than or equal to the actual throttle angle. If the second assumed TIP value results in the calculated throttle angle being equal to the actual throttle angle, the second assumed TIP value may be set as the derived TIP value. If the second assumed TIP value results in the calculated throttle angle being less than the actual throttle angle, the derived TIP value may be interpolated as being between two previous assumed TIP values.If the derived TIP value is equal to the measured TIP value, the method may include adjusting the wastegate based on the measured TIP value.

[0051] Another embodiment for a method for a turbocharged engine including a throttle includes deriving throttle inlet pressure (TIP) based on airflow through the throttle, throttle angle, and manifold absolute pressure (MAP); measuring TIP with a TIP sensor upstream of the throttle; if the derived TIP is within a threshold range of the measured TIP, adjusting engine boost pressure based on the measured TIP; and if the derived TIP is outside the threshold range of the measured TIP, adjusting boost pressure based on the derived TIP.

[0052] Deriving the TIP based on the airflow through the throttle, the throttle angle, and the MAP may further include: determining the airflow through the throttle based on a rate of change of the MAP; initially assuming that the derived TIP is equal to a lowest possible TIP; calculating a predicted throttle angle based on the lowest possible TIP, the flow through the throttle, and the MAP; comparing the predicted throttle angle to a requested throttle angle; if the predicted throttle angle is less than or equal to the requested throttle angle, confirming that the derived TIP is the lowest possible TIP;and if the calculated throttle angle is greater than the requested throttle angle, incrementally increasing the assumed TIP from the lowest possible TIP and recalculating the predicted throttle angle until the assumed TIP is incremented to a final assumed TIP value that results in the calculated throttle angle being equal to the actual throttle angle.;

[0053] The lowest possible TIP may be MAP or barometric pressure. Incrementally increasing the assumed TIP may include incrementally increasing the assumed TIP by an amount based on engine speed. Adjusting boost pressure may include adjusting a position of a wastegate coupled to a turbine of the turbocharger. The method may further include, if the inferred TIP is outside the threshold range of the measured TIP, performing a TIP sensor rationality check to determine if the TIP sensor is degraded.

[0054] It should be noted that the example control and estimation programs contained herein may be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein may be stored as executable instructions in non-volatile memory. The specific programs described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, various illustrated actions, operations, and / or functions may occur in the order illustrated, in parallel, or in some cases may be omitted.Likewise, the order of process occurrence is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations, and / or functions may be performed repeatedly, depending on the particular strategy employed. Furthermore, the described actions, operations, and / or functions may represent a graphical representation of code that may be programmed into non-transitory memory of the computer-readable storage medium in the engine control system.

[0055] It is understood that the embodiments and programs disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, as numerous variations are possible. For example, the above technology may be applied to six-cylinder engines, inline four- or six-cylinder engines, twelve-cylinder engines, four-stroke opposed-piston engines, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and embodiments and other features, functions, and / or characteristics disclosed herein.

[0056] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more of these elements, without requiring or excluding two or more of these elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. These claims, whether broader, narrower, the same, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure.

Claims

[1] Method for a motor (10) with a throttle (62) comprising: If a derived throttle inlet pressure (TIP) value differs from a measured TIP value, adjust a wastegate (72) of a turbocharger based on the derived TIP value and not based on the measured TIP value, wherein the derived TIP value is based on an air flow through the throttle (62), a throttle angle and a manifold absolute pressure (MAP). [2] Method according to claim 1, further comprising determining the measured TIP value based on an output value from a TIP sensor (122) positioned upstream of the choke (62). [3] Method according to claim 2, wherein, if the derived TIP value differs from the measured TIP value, the method further comprises performing a sensor rationality test on the TIP sensor (122). [4] Method according to claim 3, further comprising, if a TIP sensor function reduction is confirmed by the sensor rationality test, adjusting the wastegate (72) further based on subsequent derived TIP values. [5] Method according to claim 3, further comprising, if no TIP sensor function impairment is confirmed by the sensor rationality test, adjusting the wastegate (72) based on subsequent measured TIP values. [6] Method according to claim 1, further comprising determining the throughput through the throttle (62) based on a cylinder filling model which determines the throughput through the throttle (62) based on a change in the MAP. [7] Method according to claim 1, wherein deriving the TIP value comprises: Setting an initial assumed TIP value equal to the MAP value; Calculating the throttle angle based on the first assumed TIP value, the flow rate through the throttle (62), and the MAP; Comparing the calculated throttle angle with a requested throttle angle; and If the calculated throttle angle is less than or equal to the requested throttle angle, set the first assumed TIP value as the derived TIP value. [8] The method of claim 7, further comprising, if the calculated throttle angle is greater than the requested throttle angle, incrementally increasing the first assumed TIP value and recalculating the throttle angle until the first assumed TIP value is incremented to a second assumed TIP value which results in the calculated throttle angle being less than or equal to the actual throttle angle. [9] The method of claim 8, further comprising, if the second assumed TIP value results in the calculated throttle angle being equal to the actual throttle angle, setting the second assumed TIP value as the derived TIP value. [10] Method according to claim 8, further comprising, if the second assumed TIP value results in the calculated throttle angle being smaller than the actual throttle angle, interpolating the derived TIP value to be between two previous assumed TIP values. [11] Method according to claim 1, further comprising, if the derived TIP value is equal to the measured TIP value, adjusting the wastegate (72) based on the measured TIP value. [12] System that includes: a motor (10); a turbocharger fluidically coupled to the engine (10); a wastegate (72) coupled to a turbine (164) of the turbocharger; a throttle (62) positioned upstream of the motor (10) and controlling the airflow to the motor (10); and a control unit (12) that stores non-volatile instructions which can be executed as follows: to set an initial position of the wastegate (72) based on feedback from a throttle inlet pressure (TIP) sensor (122) upstream of the throttle (62); to calculate a derived TIP value and compare it with a measured TIP value from the TIP sensor (122); and If the derived TIP value differs from the measured TIP value, adjust the subsequent position of the wastegate (72) based on the derived TIP value. [13] System according to claim 12, wherein the derived TIP value is calculated based on a throttle model that estimates the TIP from the throttle angle, air flow through the throttle (62) and the intake manifold absolute pressure. [14] System according to claim 13, wherein the air flow rate through the throttle (62) is calculated based on a rate of change of the inlet manifold absolute pressure. [15] Method for a turbocharged motor (10) comprising a throttle (62), comprising: Deriving the throttle inlet pressure (TIP) based on the airflow through the throttle (62), the throttle angle and the manifold absolute pressure (MAP); Measuring the TIP with a TIP sensor upstream of the throttle (62); If the derived TIP is within a threshold range of the measured TIP, adjust the engine boost pressure (10) based on the measured TIP; and If the derived TIP is outside the threshold range of the measured TIP, adjust the boost pressure based on the derived TIP. [16] Method according to claim 15, wherein deriving the TIP based on the airflow through the throttle (62), the throttle angle and the MAP further comprises: Determining the throughput through the throttle (62) based on a rate of change of the MAP; Initial assumption that the derived TIP is equal to a lowest possible TIP; Calculating a predicted throttle angle based on the lowest possible TIP, the flow rate through the throttle (62), and the MAP; Comparing the predicted throttle angle with a requested throttle angle; If the predicted throttle angle is less than or equal to the requested throttle angle, confirm that the derived TIP is the lowest possible TIP; and If the calculated throttle angle is larger than the requested throttle angle, incrementally increase the assumed TIP from the lowest possible TIP and recalculate the predicted throttle angle until the assumed TIP is incremented to a final assumed TIP value, resulting in the calculated throttle angle being equal to the actual throttle angle. [17] Method according to claim 16, wherein the lowest possible TIP is the MAP or the barometric pressure. [18] Method according to claim 16, wherein increasing the assumed TIP incrementally comprises increasing the assumed TIP incrementally by an amount based on the engine speed. [19] Method according to claim 15, wherein adjusting the boost pressure comprises adjusting a position of a wastegate (72) coupled to a turbine (164) of the turbocharger. [20] Method according to claim 15, further comprising, if the derived TIP is outside the threshold range of the measured TIP, performing a rationality test of the TIP sensor (122) to determine whether the TIP sensor (122) is malfunctioning.

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