METHOD AND SYSTEM FOR DIAGNOSTIC BOOST PRESSURE CONTROL

Abstract

Diagnostic procedures for a turbocharged internal combustion engine in a vehicle, including: Activating a monitoring device and adjusting an actuator during the operation of an internal combustion engine with a closed-loop turbocharger boost control system by a controller, and providing an indication of deterioration by the controller based on the duration of an actual deviation exceeding a threshold deviation level between an expected change in boost pressure and an actual change in boost pressure over a driving cycle without referencing a command or measurement of a variable geometry turbine (VGT) or wastegate, where the internal combustion engine is operated by the control system with a closed-loop turbocharging control under conditions other than idle conditions, which includes any of the passage of a threshold vehicle running time, reaching a threshold combustion engine temperature and maintaining a threshold intake manifold pressure.

Description

AREA

[0001] The present description generally concerns methods and systems for diagnosing slow boost pressure control in a turbocharged internal combustion engine system. GENERAL STATE OF THE ART / BRIEF OVERVIEW

[0002] Internal combustion engine systems can be designed with charging devices such as turbochargers to provide a supercharged air charge and improve peak power output. Turbochargers incorporate a turbine in the exhaust path of the internal combustion engine, which uses some of the available exhaust energy to drive an associated compressor located upstream of the engine, forcing a higher flow of air through the intake manifold. As the turbine spins up, the exhaust pressure increases, reducing the output flow from the combustion process until the compressor raises the intake manifold pressure sufficiently to overcome the back pressure. The use of a compressor allows a smaller-displacement internal combustion engine to produce the same power output as a larger-displacement engine, but with added benefits in terms of fuel efficiency.

[0003] Boost pressure can be regulated during operation of the internal combustion engine, allowing the advantages of turbocharging to be balanced against potential problems associated with too much or too little boost. For example, in a diesel engine, insufficient boost can lead to excessive particulate matter (PM) emissions and impaired drivability. Conversely, excessive boost can result in noise, vibration, and harshness (NVH), as well as reduced exhaust gas recirculation (EGR) utilization due to higher intake manifold pressures. The reduced use of inert exhaust gases leads to higher combustion temperatures and increased NOx formation in the exhaust.In one example, the boost pressure can be controlled by adjusting the geometry of a variable geometry turbine (VGT), such as by varying the blade angle of a variable geometry turbine.

[0004] Boost pressure control systems can be regularly diagnosed, for example, via an on-board diagnostic monitor (OBD). The monitor should provide a clear fault / no fault status.

[0005] Regarding monitoring device methods, an exemplary approach by Romzek is shown in US patent US 6,457,461 B1. This patent describes a deterioration of boost control via a variable geometry turbocharger (VGT) based on a difference between the actual EGR flow rate and the expected EGR flow rate during turbocharged combustion engine operation, with the expected EGR flow rate being determined by modeling. Other approaches are based, for example, on the output of one or more boost pressure sensors, manifold pressure sensors, and throttle position sensors. Further prior art is known from US 2008 / 0022679 A1 and FR 2948415 A1.

[0006] The inventors of the present invention have, however, recognized potential problems with such approaches. For example, these approaches are based on complex and computationally intensive modeling. The required computing power may not be available in a vehicle system with limited resources. As another example, the monitoring device can be implemented intrusively, deliberately generating a significant change in the charging demand and then measuring the magnitude of the charging response. This intrusive test stimulus can disrupt the vehicle's driving behavior and emissions. If the device is implemented non-intrusively, without disrupting vehicle operation, the minimum conditions required to determine with high confidence that no defect is present may not be met. Overall, it can be challenging to provide both adequate detection and minimal disruption.As a further example, in each of the above approaches, regardless of the sensor used, the magnitude and rate of change of the sensor output can be influenced by vehicle driving conditions, such as whether the driver accelerates the vehicle gently or strongly, the frequency of application, and switching between accelerator and brake pedal use, etc. Due to an error in modeling the expected output, there may be conditions in which a significant difference between the expected and actual sensor output is incorrectly attributed to a degraded charging response, or an immaterial difference is incorrectly attributed to a non-degraded charging response.

[0007] The inventors of the present invention recognized that boost pressure control incorporates a feedback loop and that the time required for the feedback loop to respond to a pressure deviation can be used as a monitoring device. This is because the feedback must be constantly corrected due to command changes and external disturbances, making it sensitive to deterioration in the boost control response. Instead of using carefully controlled, non-feedback control command and response time tests, which require intrusive operation, the feedback control response time can be acquired non-intrusively and used to evaluate the boost control.Thus, in one example, the problems described above can be solved by a method for a turbocharged internal combustion engine. This method comprises, during the operation of an internal combustion engine with a closed-loop turbocharger control system, indicating a deterioration of the boost pressure control system based on a measured deviation between the expected boost pressure and the actual boost pressure. This deviation frequently occurs during a driving cycle when the difference is large enough that the control response should be significantly increased. The duration for which the deviation persists can be monitored. A slow response is determined if the duration exceeds a threshold duration. The detected slow response can occur for various physical reasons, such as manifold leaks and / or slow actuation, so the detection is not limited to actuator deterioration alone.Since both command changes and / or disturbances offer the possibility of observing a control error response, the boost control can be passively diagnosed in this way, provided a test is performed to confirm that an adequate driving stimulus has been applied. This is because the monitoring device must ultimately declare a fault / no fault condition for at least one-third of all qualified drives. This procedure fulfills a defined OBD requirement that the boost control system must not deteriorate in terms of response time if the degree of deterioration could affect emissions results and illuminate a Malfunction Indicator Lamp (MIL) after certain regulatory procedures are executed by the PCM diagnostic system. Furthermore, the fault of slow boost response is not limited to a specific cause.

[0008] For example, in response to a change in operator torque demand, a desired boost pressure can be determined and processed by applying a delay filter and a lag filter, the latter with a reaction time based on a time constant parameter. One or more boost actuators, such as an exhaust gas VGT or a wastegate with the same capacity, can be adjusted based on the desired boost pressure. For instance, in response to an increase in the desired boost pressure, the wastegate opening can be reduced. Simultaneously, a pressure deviation between the expected (filtered, processed form of the desired) boost pressure and the actual pressure can be checked to ensure it lies outside a range defined by lower and upper limits.Furthermore, if qualifying vehicle operating conditions are met, such as a minimum vehicle running time, a minimum manifold pressure, and a minimum combustion engine temperature, an internal combustion engine control unit (ECU) can track the response time of boost pressure deviations outside permissible limits. That is, the ECU can measure the duration elapsed when the expected and actual pressures differ sufficiently to fall outside the upper or lower limits (for example, a duration during which the pressure deviation remains above a threshold deviation level). A disturbance that has altered the boost pressure, even though the command was steady, will also result in a deviation error, which can be evaluated in the same way.The qualifying vehicle operating conditions, along with the upper and lower limits of the pressure deviation, can ensure that deviations from the limit conditions are confirmed if the response time can be reliably used to evaluate the response time of the boost pressure control system. If the measured response time is higher than a threshold duration, such as higher than the maximum response time of a known nominal system for qualified conditions, the control unit can infer a deterioration in boost performance to inform both the required regulatory OBD monitoring device and to alert the driver to the deteriorated operation.

[0009] In this way, by evaluating the response time of a boost control system to a pressure deviation that is not specifically dependent on the command or position of the boost actuators (such as a wastegate), deteriorating boost response can be distinguished from a normal, intentionally slow response. Requiring the deviation to exceed a threshold ensures an increased control response that should trigger a rapid correction (and if it is not rapid, a fault is likely present). The purpose of using defined upper and lower limits is to better account for differences in response time to boost pressure overshoots versus undershoots, as the control system can be fine-tuned to react differently to each, thus reducing the likelihood of erroneous fault / no fault indications.By confirming qualifying vehicle operating conditions, the response time can be compared only under conditions where the results are reliable. In particular, idling and near-idle operating conditions can be avoided if response times are unreliable. By confirming that operating conditions match those of a full test run, the charge monitoring device can be used with a higher confidence factor. Non-intrusive test execution provides adequate data collection without interfering with the vehicle's drivability or emissions. Furthermore, the monitoring device can be run without requiring complex and computationally intensive modeling. Overall, boost control can be better diagnosed and addressed promptly, thereby improving the performance of the turbocharged internal combustion engine.

[0010] It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in more detail in the detailed description. It is not intended to identify important or essential features of the claimed subject matter, the scope of protection of which is defined solely by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that overcome the disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows an example of a turbocharged internal combustion engine system. Fig. Figures 2A-2B show a high-level flowchart of an exemplary procedure for diagnosing deterioration of a boost pressure control system based on the response time of a feedback control and the evaluation of an appropriate stimulus to detect a potential defect. Fig. Figure 3 shows a high-level flowchart of an exemplary procedure for determining the pressure deviation of the boost pressure control. Fig. Figure 4 shows relevant boost pressure signals that are used to determine the pressure deviation. Fig. 5 and Fig. Figure 6 shows examples of a fault-free and faulty boost pressure control diagnosis based on the reaction time of the feedback control. DETAILED DESCRIPTION

[0011] The following description concerns systems and procedures for diagnosing a turbocharging control system in a turbocharged internal combustion engine system, such as the internal combustion engine system from Fig. 1. An internal combustion engine control unit can be configured to run a control routine, such as the exemplary routine from Fig. 2A-2B are used to diagnose boost control capabilities based on the feedback response time to a boost pressure deviation. The response time can be monitored after confirming that qualifying operating conditions are present, such as those found in Fig. 3 are designed to better account for response time deviations resulting from pressure overruns, underruns, or idle conditions of the internal combustion engine. An exemplary variation of the desired, expected, and actual boost pressure in a fault-free turbocharged internal combustion engine system is shown in Fig. 4 shown. A possible example of a boost pressure diagnosis is shown with reference to Fig. 5 and Fig. Figure 6 shows this. In this way, the performance of a turbocharged internal combustion engine is monitored and a system failure of the turbocharger response control can be diagnosed.

[0012] Fig. Figure 1 shows an example of a combustion chamber or cylinder of an internal combustion engine 10 coupled to a vehicle 5. In some examples, the vehicle 5 may be a hybrid vehicle with multiple torque sources available to one or more vehicle wheels 55. In other examples, the vehicle 5 is a conventional vehicle with only an internal combustion engine or an electric vehicle with only one electric machine. In the example shown, the vehicle 5 includes an internal combustion engine 10 and an electric machine 52. The electric machine 52 may be an electric motor or an electric motor / generator. The crankshaft 140 of the internal combustion engine 10 and the electric machine 52 are connected to the vehicle wheels 55 via a transmission 54 when one or more clutches 56 are engaged.In the illustrated example, a first clutch 56 is provided between the crankshaft 140 and the electric machine 52, and a second clutch 56 is provided between the electric machine 52 and the transmission 54. The controller 12 can send a signal to an actuator of each clutch 56 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft 140 from the electric machine 52 and its associated components, and / or connecting or disconnecting the electric machine 52 from the transmission 54 and its associated components. The transmission 54 can be a manual transmission, 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.

[0013] The electric machine 52 receives electrical power from a traction battery 58 to provide torque to the vehicle wheels 55. The electric machine 52 can also be operated as a generator to provide electrical power for charging the battery 58, for example, during braking.

[0014] The internal combustion engine 10 can be controlled, at least partially, by a control system comprising a controller 12 and by input from a vehicle operator 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. The cylinder (here also referred to as the "combustion chamber") 14 of the internal combustion engine 10 can include combustion chamber walls 136 in which a piston 138 is positioned. The piston 138 can be coupled to a crankshaft 140, so that a reciprocating motion of the piston is translated into a rotational motion of the crankshaft. The crankshaft 140 can be coupled to at least one drive wheel of the passenger car via a transmission system. Furthermore, a starter electric motor (not shown) can be coupled to the crankshaft 140 via a flywheel to enable the starting of the internal combustion engine 10.

[0015] Cylinder 14 can draw in intake air via a series of intake air ducts 142, 144, and 146. Intake air duct 146 can communicate with other cylinders of the internal combustion engine 10 in addition to cylinder 14. In some examples, one or more of the intake ducts may include a charging device, such as a turbocharger or a supercharger. For example, illustrates Fig. 1. The internal combustion engine 10 is configured with a turbocharger, including a compressor 174 located between the intake ports 142 and 144, and an exhaust turbine 176 located along the exhaust port 148. The compressor 174 can be powered, at least partially, via a shaft 180 through the exhaust turbine 176 when the charging device is configured as a turbocharger. In other examples, such as when the internal combustion engine 10 is equipped with a compressor, the exhaust turbine 176 can be optionally omitted, with the compressor 174 being driven by mechanical inputs from an electric motor or the internal combustion engine. A throttle 162, which includes a throttle valve 164, can be provided along an intake port of the internal combustion engine to vary the flow rate and / or pressure of the intake air supplied to the internal combustion engine cylinders.For example, the throttle 162 can be positioned downstream of the compressor 174, as in . Fig. 1 shown, or alternatively it can be provided upstream of the compressor 174.

[0016] Exhaust gas is directed into turbine 116 to drive the turbine. If reduced turbine torque is desired, a portion of the exhaust gas can instead be routed through wastegate 90, bypassing turbine 176. A wastegate valve 92 can be actuated to open, allowing at least some of the exhaust pressure from upstream of the turbine to be released via wastegate 90 to a point downstream of the turbine. By reducing the exhaust pressure upstream of turbine 176, the turbine speed can be reduced, thereby decreasing the boost pressure supplied by compressor 174. In further examples, where turbine 176 is a variable geometry turbine (VGT), the boost pressure can be increased or decreased by adjusting a geometry of the turbine (e.g., the angle of the VGT blades).

[0017] The exhaust channel 148 can receive exhaust gases from other cylinders of the internal combustion engine 10 in addition to those from cylinder 14. The exhaust gas sensor 128 is shown coupled to an exhaust channel 148, which is located upstream of an emission control device 178. The sensor 128 can be selected from various suitable sensors for providing an indication of an exhaust air-fuel ratio, such as a linear lambda sensor or UEGO sensor (Universal Exhaust Gas Oxygen Sensor or wideband lambda sensor), a dual-state lambda sensor or EGO sensor (as shown), a HEGO sensor (heated EGO sensor), a NOx, HC, or CO sensor. The emission control device 178 can be a three-way catalytic converter (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0018] Each cylinder of the internal combustion engine 10 can include one or more intake valves and one or more exhaust valves. For example, cylinder 14, as shown, has at least one intake control valve 150 and at least one exhaust control valve 156, which are arranged in an upper region of cylinder 14. In some embodiments, each cylinder of the internal combustion engine 10, which includes cylinder 14, can have at least two intake control valves and at least two exhaust control valves, which are arranged in an upper region of the cylinder.

[0019] The inlet valve 150 can be controlled by the controller 12 via an actuator 152. Similarly, the exhaust valve 156 can be controlled by the controller 12 via the actuator 154. Under certain conditions, the controller 12 can vary the signals provided to the actuators 152 and 154 to control the opening and closing of the respective inlet and exhaust valves. The position of the inlet valve 150 and the exhaust valve 156 can be determined by appropriate valve position sensors (not shown). The valve actuators can be of the electric type, the cam type, or a combination thereof. The inlet and exhaust valve actuation can be controlled simultaneously, or any of the following options can be used: variable inlet cam actuation, variable exhaust cam actuation, dual independent variable cam actuation, or fixed cam actuation.Each cam actuation system can include one or more cams and use one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which can be operated by the control unit 12, to vary the valve operation. For example, cylinder 14 can alternatively include an intake valve controlled by an electronic valve actuation system and an exhaust valve controlled by a cam actuation system, including CPS and / or VCT. In other examples, the intake and exhaust valves can be controlled by a common valve actuator or actuation system, or by a variable valve timing actuator or actuation system.

[0020] Cylinder 14 can have a compression ratio that is the volume ratio between piston 138 at bottom dead center and at top dead center. In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples where different fuels are used, the compression ratio can be higher. This can occur, for example, when fuels with a higher octane rating or fuels with a higher latent heat of vaporization are used. The compression ratio can also be higher when using direct injection due to its effect on internal combustion engine knock.

[0021] In some examples, each cylinder of the internal combustion engine 10 may include a spark plug 192 to initiate combustion. Under selected operating modes, an ignition system 190 of the combustion chamber 14 may provide a spark via a spark plug 192 in response to a spark advance signal SA from the control unit 12. However, in some embodiments, the spark plug 192 may be omitted, such as when the internal combustion engine 10 can initiate combustion by auto-ignition or by fuel injection, as may be the case with some diesel engines.

[0022] In some examples, each cylinder of the internal combustion engine 10 may be configured with one or more fuel injection devices to supply it with fuel. As a non-restrictive example, cylinder 14, as shown, includes two fuel injection devices 166 and 170. The fuel injection devices 166 and 170 may be configured to deliver fuel drawn from the fuel system 8. The fuel system 8 may include one or more fuel tanks, fuel pumps, and fuel distributors. As shown, the fuel injection device 166 is directly coupled to cylinder 14 to inject fuel directly into it in proportion to the pulse width of the signal FPW-1, which is received by the controller 12 via an electronic driver 168.The fuel injection device 166 provides so-called direct injection (hereinafter referred to as "DI") of fuel into the combustion cylinder 14. Although... Fig. Figure 1 shows the injection device 166 positioned on one side of the cylinder 14. Alternatively, it can be located above the piston, for example, near the spark plug 192. Such a position can improve mixing and combustion when the internal combustion engine is operated with an alcohol-based fuel, as some alcohol-based fuels have lower volatility. Alternatively, the injection device can be located above and near the intake valve to improve mixing. Fuel can be supplied to the fuel injection device 166 from a fuel tank of the fuel system 8 via a high-pressure fuel pump and fuel distributor. Furthermore, the fuel tank can have a pressure converter that provides a signal to the control unit 12.

[0023] As shown, the fuel injection device 170 is located in the intake port 146 and not in the cylinder 14, a configuration that provides what is known as port fuel injection (hereinafter referred to as "PFI") into the intake port upstream of the cylinder 14. The fuel injection device 170 can inject fuel taken from the fuel system 8 proportionally to the pulse width of the FPW-2 signal received by the controller 12 via the electronic driver 171. It should be noted that a single driver 168 or 171 can be used for both fuel injection systems, or, as shown, several drivers can be used, for example, driver 168 for fuel injection device 166 and driver 171 for fuel injection device 170.

[0024] In an alternative example, each of the fuel injection devices 166 and 170 can be configured as a direct fuel injection device for injecting fuel directly into cylinder 14. In yet another example, each of the fuel injection devices 166 and 170 can be configured as a port fuel injection device for injecting fuel upstream of the intake valve 150. In still further examples, cylinder 14 can contain only a single fuel injection device configured to receive different fuels in varying relative amounts as a fuel mixture from the fuel systems, and further configured to inject this fuel mixture either as a direct fuel injection device directly into the cylinder or as a port fuel injection device upstream of the intake valves.It should therefore be understood that the fuel systems described here are not limited by the specific configurations of fuel injection devices described here as examples.

[0025] Fuel can be supplied to the cylinder by either injection device during a single cylinder cycle. For example, each injection device can provide a portion of the total fuel injection that is burned in cylinder 14. Furthermore, the distribution and / or relative amount of fuel supplied by each injection device can vary with operating conditions, such as combustion engine load, knocking, and exhaust gas temperature, as described below. Fuel injected into the intake manifold can be supplied during an open intake valve event, a closed intake valve event (e.g., essentially before the intake stroke), and during operation with both the open and closed intake valves.Similarly, directly injected fuel can be supplied, for example, during an intake stroke, partially during a preceding exhaust stroke, during the intake stroke, and partially during the compression stroke. Thus, even in a single combustion event, injected fuel can be injected from the intake manifold and direct injection systems at different times. Furthermore, multiple injections of the delivered fuel can be performed per cycle during a single combustion event. These multiple injections can occur during the compression stroke, the intake stroke, or any suitable combination thereof.

[0026] As described above, Fig. 1 only one cylinder of a multi-cylinder internal combustion engine. Accordingly, each cylinder can likewise have its own set of intake / exhaust valves, fuel injection device(s), spark plug, etc. It is understood that the internal combustion engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12 or more cylinders. Furthermore, each of these cylinders can include some or all of the various components that are described in Fig. 1 with reference to cylinder 14 are described and illustrated.

[0027] The fuel injection devices 166 and 170 can have different characteristics. These include differences in size; for example, one injection device may have a larger injection orifice than the other. Other differences include, but are not limited to, different spray angles, different operating temperatures, different objectives, different injection timings, different spray characteristics, different positions, etc. Furthermore, different effects can be achieved depending on the distribution ratio of the injected fuel between the injection devices 170 and 166.

[0028] Fuel tanks in fuel system 8 can contain different types of fuel, such as fuels with varying properties and compositions. These differences can include variations in alcohol content, water content, octane rating, heats of vaporization, fuel blends, and / or combinations thereof. For example, fuels with different heats of vaporization could use gasoline as the primary fuel type, with a lower heat of vaporization, and ethanol as the secondary fuel type, with a higher heat of vaporization. Alternatively, the internal combustion engine could use gasoline as the primary fuel type and an alcoholic fuel blend, such as E85 (approximately 85% ethanol and 15% gasoline) or M85 (approximately 85% methanol and 15% gasoline), as the secondary fuel type.Other possible substances include water, methanol, a mixture of alcohol and water, a mixture of water and methanol, a mixture of alcohols, etc.

[0029] In yet another example, both fuels could be alcohol mixtures with varying alcohol compositions. The first fuel could be a gasoline-alcohol mixture with a lower alcohol concentration, such as E10 (which consists of approximately 10% ethanol), while the second fuel could be a gasoline-alcohol mixture with a higher alcohol concentration, such as E85 (which consists of approximately 85% ethanol). Furthermore, the first and second fuels could also differ in other fuel properties, such as temperature, viscosity, octane rating, etc. Additionally, the fuel properties of one or both fuel tanks can change frequently, for example, due to daily fluctuations in refueling.

[0030] Control 12 is in Fig. 1 is represented as a microcomputer comprising a microprocessor unit 106, input / output ports 108, an electronic storage medium for executable programs and calibration values, in this specific example represented as non-volatile read-only memory 110 for storing executable instructions, random access memory 112, keep-alive memory 114 and a data bus.In addition to the signals discussed previously, the control unit 12 can receive various signals from sensors coupled to the internal combustion engine 10, including the measurement of mass air flow (MAF) from the mass air flow sensor 122; engine coolant temperature (ECT) from the temperature sensor 116, which is coupled to the cooling sleeve 118; a profile ignition pickup signal (PIP) from the Hall effect sensor 120 (or other type), which is coupled to the crankshaft 140; throttle position (TP) from a throttle position sensor; and absolute manifold pressure (MAP) from sensor 124. An engine speed signal (rpm) can be generated by the control unit 12 from the PIP signal. The manifold pressure signal MAP from a manifold pressure sensor can be used to provide an indication of vacuum or pressure in the intake manifold.

[0031] The controller 12 receives signals from the various sensors. Fig. 1 and suspends the various actuators Fig. 1. The controller uses this information to adjust the internal combustion engine operation based on received signals and instructions stored in a memory of the controller. For example, in response to an increase in operator torque demand, as indicated by input from a pedal position sensor (during a pedal actuation event), the controller can increase the boost pressure output from the internal combustion engine by sending a control signal to the wastegate actuator to open the wastegate valve to a more closed position. Similarly, in response to a decrease in operator torque demand, as indicated by input from a pedal position sensor (during a pedal release event), the controller can increase the boost pressure output from the internal combustion engine by sending a control signal to the wastegate actuator to open the wastegate valve to a more closed position.In one example, the boost pressure can be controlled via a boost control module of the control unit.

[0032] By using a turbocharger, the power output of an internal combustion engine can be increased for a given cylinder displacement. Additional synergistic benefits are also achieved. The turbocharger's turbine, located in the exhaust system of the internal combustion engine, uses some of the available exhaust energy to drive the associated compressor, which forces a higher flow of air through the intake manifold. As the turbine spools up, the exhaust pressure increases, reducing the output flow from the combustion process until the compressor sufficiently boosts the intake manifold pressure to overcome the back pressure.

[0033] The advantages of turbocharged systems must be weighed against several drawbacks, which increase as boost pressure reaches high levels. In a diesel engine, insufficient boost leads to excessive particulate emissions and reduced drivability, while excessive boost results in noise, vibration, harshness (NVH) and restricts exhaust gas recirculation (EGR) due to higher intake manifold pressures. The reduction in inert exhaust gas can lead to higher combustion temperatures and promotes NOx formation. Such a turbocharged combustion engine system may require careful coordination of trade-offs to deliver the necessary engine power while simultaneously limiting boost pressure to avoid prolonged combustion at high boost, which increases exhaust emissions.

[0034] As discussed above, turbocharger operation can be controlled by adjusting components or actuators of a boost control system, such as by releasing exhaust pressure either by bypassing the turbine blades (such as with a 90° wastegate) or by altering the turbine geometry, such as the blade angle, to vary its exhaust energy absorption. The design of a turbocharged internal combustion engine results in an upstream airflow and injected fuel that typically generates excessive boost pressure unless variable geometry turbocharger (VGT) or another high-performance wastegate is used to control the boost level. The trade-off is determined by the engine's mapping and the targeting of an acceptable boost pressure. Other internal combustion engine systems, such as exhaust gas recirculation (EGR) and variable camshaft timing (VCT), can also affect boost pressure.These other factors are also planned for, but transient operation and / or persistent control deviations can lead to boost pressures that deviate from the desired level. One exemplary approach to rejecting these disturbances involves assigning the VGT to a closed-loop control system to maintain the desired boost pressure. The boost pressure response in closed-loop control is dominated by manifold filling dynamics, which are much slower than the VGT actuation. Typically, the VGT responds to a commanded correction within a few hundred milliseconds, but the overall feedback system may take several seconds to reject a disturbance.

[0035] To enable regulated exhaust emissions, an on-board diagnostic monitoring device (OBD monitoring device) can attempt a test for each trip or "route" of the vehicle that meets a minimum set of criteria (such as a minimum vehicle running time at 0 mph and above 25 mph, acceptable ambient temperatures and pressures, etc.). The OBD test must conclude that the turbocharged internal combustion engine system is fault-free or faulty for at least one-third of all valid trips. An example OBD test may be specifically directed at the boost pressure control system, providing the possibility that control actuators, such as the VGT, create a slow boost pressure control fault to test the fault monitoring device.Intrusive OBD tests can intentionally use the boost pressure control system to assess its ability to respond to an intrusively created pressure deviation, solely for the purpose of fulfilling the OBD test. One advantage of the intrusive system is that the vehicle's control system can actively pursue ways to detect a potential fault and, if no fault is detected, declare the vehicle fault-free for the trip and meet the trip test completion metric. However, the test stimulus of the intrusive test can potentially disrupt vehicle behavior and emissions, making it challenging to achieve both adequate detection and minimal disruption with this approach.

[0036] OBD test requirements can also be met through passive acquisition. Instead of intentionally stimulating the system's actuators to detect a fault, the control system can observe the normal behavior of the boost control system and look for indications that the system is faulty. The minimum conditions required to qualify a drive as a valid test case may not always provide sufficient actuator operation for a given OBD test to reliably distinguish a fault-free result from a fault result with high confidence, thus creating a considerable challenge. The advantage of passive testing is that the nominal system does not have to risk interference from intentional intrusive operation.

[0037] As explained here, a passive (non-intrusive) approach can be used to meet OBD test requirements while still providing reliable results. As referenced in Fig. As described in 2, an internal combustion engine control system can evaluate the performance of the feedback response of the boost control system while focusing on the transient difference or deviation of the desired and actual boost pressure, rather than focusing on the type or level of the actuator setting (e.g., independent of a wastegate command or a measured position).

[0038] In this way, the components can be made from Fig. 1. A vehicle system comprising an internal combustion engine; a turbocharger including an intake compressor driven by an exhaust turbine; a VGT or wastegate valve arranged in a wastegate coupled across the exhaust turbine; a timer; and a controller with computer-readable instructions stored in non-volatile memory to: in response to a change in the requested boost pressure, set a position of the wastegate valve and initiate the timer; monitor a duration elapsed on the timer to complete a pressure deviation corresponding to the change in the requested boost pressure after setting; and, in response to the duration being longer than a threshold, indicate a deterioration in the intake boost pressure response time.The control system may include further instructions for monitoring duration in response to the fulfillment of qualifying vehicle operating conditions, including a minimum vehicle running time; a threshold combustion engine temperature estimated by an internal combustion engine temperature sensor; a minimum intake manifold pressure level estimated by an intake manifold pressure sensor; and a minimum rate of change of injected fuel mass commanded to a fuel injection device of an internal combustion engine cylinder.The controller can include further instructions for processing the desired pressure via a delay filter and a lag filter, each with a time constant parameter, to generate an expected boost pressure. This allows a pressure deviation signal to be generated by using the difference between the expected and actual values. The controller also monitors the pressure deviation between upper and lower limits, where the upper limit is based on a tolerance for undershooting and the lower limit on a tolerance for overshooting. In both undershoot and overshoot conditions, as soon as the deviation exceeds the limits, the feedback will trigger a sufficiently strong control response to correct the deviation, enabling the monitoring device to detect a potentially faulty, slow response.It should be noted that control systems tend to reduce the control force when the target is almost reached and the response tends to slow down to achieve smoother operation, so that even the responsiveness of a defective system is not exceeded; thus, a minimal deviation outside the limits is required.

[0039] With reference to Fig. Figures 2A-2B now show an exemplary Method 200 for diagnosing the response of a boost pressure control system, including verifying an appropriate stimulus required to detect a fault. The Method enables non-intrusive diagnosis of the boost pressure control based on the response time of a boost pressure feedback loop that responds to various boost pressure variations during a driving cycle. Instructions for executing Method 200 and the other Methods included herein can be executed by a controller based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the internal combustion engine system, such as those described above with reference to Fig. 1. Sensors described. The control unit can use combustion engine actuators of the combustion engine system to adjust the combustion engine operation according to the procedures described below. It will be understood that Fig. 2B a continuation of the procedure 200 from Fig. 2A is, and that the procedure 300 from Fig. 3 aspects of step 208 Fig. 2A is listed.

[0040] At 202, the procedure inputs estimated and / or measured vehicle and internal combustion engine operating conditions collected by the internal combustion engine control unit (e.g., the powertrain control module - PCM). These may include, as non-limiting examples, internal combustion engine speed, vehicle speed, internal combustion engine temperature, environmental conditions such as ambient temperature, air pressure, humidity, fuel injection mass, measured boost pressure, internal combustion engine running time since last start, EGR flow rate, current boost pressure, current wastegate valve position, manifold flow and pressure, exhaust gas temperature, etc. Accordingly, the internal combustion engine may, during the routine of Fig. 2A-2B must be operated with a closed-circuit charging control system.

[0041] At 204, the procedure checks a subset of the input conditions collected by the PCM, such as minimum runtime, minimum combustion engine coolant temperature, and minimum intake manifold pressure, to determine whether the vehicle operating conditions match the input conditions for the boost control device. The minimum runtime, which might be 25 seconds for example, ensures that the vehicle subsystems have completed initialization for driving, allowing normal boost control to begin. The minimum combustion engine coolant temperature, 44°C in one example, ensures that the combustion engine components related to the intake manifold and boost control are sufficiently warm for normal operation.The minimum intake manifold pressure, in one example 1500 hPa, is large enough to ensure that the internal combustion engine is not idling or undergoing heavy deceleration, where the expected boost pressure estimate might not be sufficiently accurate. If any of the checked input conditions are not met, at 206 a pressure deviation timer is reset, a test timer is stopped and left at its current level, and the monitoring device waits to try again when the PCM execution returns to the next execution cycle. If all input conditions match, the procedure can proceed to 208 and 226 simultaneously. Details of the subroutine starting at 226 are in [reference missing]. Fig. 2B shown, which is a continuation of Fig. 2A is. Procedure 200 requires that the PCM, in a given pass, executes both paths (the path starting at 208 as well as the path starting at 226) as long as the conditions allow, and then tries them again in the next pass. Thus, the Fig. 2A-2B, that the procedure returns to the start if conditions are blocked (if the answer to a question is "NO").

[0042] It will be understood that in some examples the monitoring device from the Fig. 2A-2B can be initiated or triggered in response to a change in operator torque demand, such as a change in operator torque demand exceeding a threshold that necessitates a change in boost pressure supply. For example, a change in operator torque demand can be acknowledged when the operator depresses or releases the accelerator pedal by more than a threshold amount. If a change in operator torque demand is not acknowledged, or if the change is less than the threshold change and does not require a change in boost pressure supply, the monitoring device may not be triggered, and the boost actuator settings, such as a wastegate position or turbine geometry (e.g., turbine blade angle), can be maintained.A sub-module of the PCM can be designed to determine the desired boost pressure when the operator torque requirement changes, with the sub-module responsible for determining the boost pressure being distinct from a sub-module of the PCM responsible for executing the monitoring device. Fig. 2A-2B is responsible, distinguishes. n.

[0043] Returning to 208, the pressure deviation is calculated, and this is in Fig. 3 is described in more detail. In section 210, the pressure deviation is compared to an upper (Thr_U) and a lower (Thr_L) set of limits that define a range within which the pressure deviation is considered to be within a nominal system range. Accordingly, different pressure deviations can have different effects on the feedback response time and performance of the boost control system. Since the method is based in particular on the feedback nature of the boost control system, the feedback response can vary depending on the type and magnitude of the pressure deviation that triggered the feedback response. Furthermore, even in fault-free systems, some pressure deviations may be present. Additionally, pressure deviations can be influenced by driver behavior. For example, strong acceleration can challenge the boost pressure control differently than gentle driving.Similarly, a pressure overshoot deviation (where the desired boost pressure is lower than the actual boost pressure) can have a different effect on boost pressure control compared to a pressure undershoot deviation (where the desired boost pressure is higher than the actual pressure). As another example, boost pressure degradation due to a slowed VGT (Variable Gearbox Technology) defect may not be detected by monitoring the boost pressure if the VGT is never tasked with providing boost pressure correction. Conversely, strong vehicle acceleration in a fault-free system can produce a significant pressure deviation compared to a faulty system subjected to only weak acceleration.Therefore, the challenge for the OBD test lies in capturing an aspect of the control response and pressure deviation that distinguishes a defective response from a defect-free one when a simple check of the magnitude of the deviation is insufficient.

[0044] In one example, boost pressure deviations are only valid monitoring conditions if they fall outside an upper or lower limit. That is, boost pressure deviations higher than the upper limit and lower than the lower limit can be used for OBD testing of the boost pressure control system. The upper and lower limits can define upper and lower boundaries within which the response time of a pressure deviation cannot be reliably correlated with boost pressure control degradation. Specifically, a positive pressure deviation indicates that the system is experiencing a fault due to falling below the desired value, while a negative pressure deviation indicates that the system has experienced a fault due to exceeding the desired value.The required threshold levels are designed to create a fault large enough to force the closed-loop control system to make a substantial correction, thus testing the system's available responsiveness. A fault that is too small will trigger much smaller corrections, to which a faulty system with a slow response can adequately react. By limiting the diagnostics to pressure deviations outside the upper and lower thresholds, differences in response time to a boost pressure drop versus a boost pressure surge can be accounted for when determining a fault. By setting these thresholds, the control system specifically examines only strong control responses where the rate of boost response is critical and is able to more reliably establish clear boundaries between relevant and irrelevant deviations.

[0045] In one example, the controller can collect data over multiple driving cycles and road trips under both fault and fault-free conditions and refine the limits based on this data to arrive at a solution. However, an analysis of the control loop (constructed from the control electronics and actual physical components) and the control algorithm can be helpful. For example, if PI controller tuning and insensitivity error processing are used, it may be possible to see at what error level the controller behavior becomes very cautious for smaller errors and only slowly approaches a target—an operating mode that a system with a slow response would not reveal.

[0046] If the result at 210 is incorrect, meaning the deviation is within the nominal range between the upper and lower limits, the deviation timer is reset at 212, and it is determined that this path of the procedure must be followed until the next PCM pass. If the deviation is outside the nominal range, the procedure proceeds to 214, where the deviation timer is allowed to advance for this PCM pass. At 216, this advanced deviation timer is compared with the previous timer value, and if it is greater, the controller replaces the last value at 218 with the most recently acquired value. If it is not greater, the controller does not replace the last value at 220, as it is still the highest value found.In this way, the highest level reached by the timer is recorded for a given trip, even if the deviation timer has been reset and vehicle conditions require a new attempt to build up a deviation time. This logged deviation timer value is then compared to a deviation threshold time at 222. If the threshold has not yet been reached, this path is considered complete until the next iteration. Here, the deviation timer is not reset but may instead be reset during the next iteration through 202 to 216 based on changing conditions, or it may further increase the logged deviation if the fault conditions persist. If the deviation threshold is reached, the procedure indicates at 224 that a fault with a slow charging response is present on this trip.At this point, the procedure is complete, as a defect has been found, even if more testing time is permissible (as explained in 234). Fig. 2A shows the end of the monitoring device at 224 here as optional, in case another system wants to see further examples of defective behavior (such as during vehicle pre-production development or scan tool debugging when the vehicle is being repaired).

[0047] The monitoring device then proceeds to step 238, evaluating the defect along with confirmation that sufficient test time has elapsed. The part of the monitoring device that confirms the test time is located in Fig. 2B was performed at steps 226-236.

[0048] The path beginning at 226 and its subsequent steps must also be executed as far as possible, similar to the path followed by steps 204-224. At 226, the path must determine whether adequate stimulus was applied during the drive so that, if a fault had been present, it would have been sufficiently detected to be found by the path from 208 to 224. Step 226 involves using the injected fuel mass value retrieved from the PCM to calculate a rate of change of this variable using a standard first-order derivative determination. At 228, the rate of change of the mass injection is compared to a threshold value, which, if exceeded, indicates that there is sufficient disturbance in the boost control system for a faulty system to react too slowly based on the pressure deviation.If the mass injection rate is too low, step 230 terminates this PCM run to update the test timer; otherwise, step 232 advances a timer if conditions are suitable for fault detection. At step 234, the test timer is calibrated against a maximum allowable time if conditions suitable for fault testing were present. If allowable time remains, the procedure may monitor further PCM runs; however, if the allowable time has been exceeded, the procedure proceeds at step 236, warning the rest of the PCM that the allowable time has expired. If step 224 did not detect any deviation time at the threshold level during the drive, and step 236 declared the test complete, the procedure concludes at step 238 that no fault occurred during this drive.At this point, the procedure must stop at 240 until the PCM's OBD guidance program allows further operation (usually the next drive), at which time all procedure condition conditions are normally reset.

[0049] It is possible that a defect could be detected by a system disturbance not caused by the mass injection change, and sections 208 to 224 of the procedure still detect the slow response, which is desirable. However, for the purpose of determining a defect-free condition, the procedure is forced to use a known slow-response stimulus to check for appropriate conditions to detect a defect. A defective system is usually detected during most qualified runs before the allowable test time is exhausted, but checking the allowable time is intended to ensure that a defect-free determination is justified. This reduces the likelihood of false defect detections.

[0050] Fig. 3 describes block 208 from Fig. 2A in more detail. Procedure 300 shows an exemplary procedure for determining the pressure deviation that results from the monitoring procedure 200. Fig. 2A-2B is used. Step 302 involves retrieving the desired boost pressure calculated by the PCM from the control unit's memory. The desired boost pressure is a diesel internal combustion engine calculation based on an operator torque requirement, primarily derived from the pedal position, but also on many subsystem settings required to ensure smooth operation, fuel efficiency, and emissions. This is illustrated by creating the conditions necessary to allow proper EGR flow.Boost pressure is subject to mass flow, engine speed, and the operation of the VGT (or wastegate), but the PCM has limited freedom to adjust engine speed (via gear selection, torque converter slip) and mass injection (fuel rail pressure and fuel injection timing) because meeting operator demand must always take precedence. Therefore, the PCM must primarily rely on the VGT to achieve the desired boost pressure. Although, as stated above, the VGT plays a significant role in boost control and may be a preferred way for the monitoring system to illustrate this, other factors can be responsible for a slow response.The method described here uses the desired boost pressure as an input and does not reference the VGT command or its measured position, as the method should be able to detect a slow response regardless of whether the VGT is the underlying cause or not. In this way, the method allows a slow boost response to be detected irrespective of the direction and magnitude of any wastegate or VGT actuator settings used during boost pressure control.

[0051] In step 304, the desired boost pressure is processed by passing the signal through a delay filter and then a lag filter, controlled by a time constant (TC) parameter. The resulting signal is an expected boost pressure that should be present when the system is responding normally (without defects). In one example, the delay and lag filters are fixed delay and fixed lag filters. In step 306, the PCM's value for the actual boost pressure is mapped to the actual value used by the procedure.This step allows the trivial use of a simple measured sensor value, but in some systems the PCM may need to combine a representative signal from multiple sensors, or offer slightly different measurement-based signals that have been processed differently to eliminate noise at various frequencies, so the procedure should select the most suitable actual available pressure. Step 308 then subtracts the actual value from the expected value to obtain a pressure deviation, which is measured at 210 in. Fig. 2A can be passed on.

[0052] The intention behind 304 is to reasonably estimate what a normal charging response should look like without resorting to expensive dynamic online models that exceed the resources to be tuned and executed on a PCM. The procedure can be achieved by using a simple fixed set of options ranging from pure delay (an example is given in Fig. 4 shown, which has a delay of 0.4 seconds) and a lagging filter time constant (TC) (the example shown in Fig. As shown in Figure 4, a TC of 0.5 seconds is required. Further refinement in adjusting the actual nominal boost pressure is possible by implementing the delay and TC functions for other internal combustion engine conditions, such as engine speed and mass injection; however, this introduces additional complexity and can therefore be avoided in this example. In this example, processing the desired boost pressure via the fixed delay and fixed time constant lag filter allows the controller to predict, in a compact manner, what the measured boost pressure should be for a fault-free boost control system. When the actual boost pressure is compared to this value, a faulty case should exhibit a large difference that can be easily detected and identified.Accordingly, the boost pressure feedback control's ability to reject disturbances can be limited due to the relatively long loop time of the overall system, primarily hindered by the presence of pure delays and a certain amount of lagging dynamic response. The pure delay restricts the feedback control from taking immediate action to reject disturbances because there is no indication that a fault has occurred until the delay has passed, during which time the actual system boost pressure may deviate from the target pressure. Once the fault begins to reach the pressure sensor, which provides feedback to the boost pressure control system (this feedback can be dampened by the lagging dynamics), the control can begin to correct the situation, although the full extent of the disturbance cannot be detected until the lagging has ceased.To a certain extent, feedback control systems can be improved to cope with known delay and lag conditions, but a mere delay will always limit the feedback control's ability to completely suppress a disturbance. The inventors of the present invention have recognized that, if not hindered by a defect, the closed-loop response of the boost control system to the desired boost pressure can be similar to an open-loop response with a delay and lag. Therefore, by processing the desired boost pressure through the delay and lag filter, the need to model the boost pressure response based on many internal combustion engine and VGT signals is reduced. Consequently, a significant reduction in computational cost and complexity is achieved while providing a sufficient approximation.It will be understood that in alternative examples, the lag and delay parameters can be variable rather than fixed, with the parameters varying based on one or more internal combustion engine parameters. However, using variable lag and delay parameters can increase computational costs and measurement complexity. Therefore, using fixed lag and delay parameters strikes a balance between accuracy and complexity.

[0053] As with reference to Fig. 4. Even when performed correctly, a fault-free, actual boost pressure can still exceed or fall short of the expected boost pressure in selected combustion engine operating ranges. Therefore, by restricting the diagnostic test to not being applied during such conditions, a slow boost response is not incorrectly correlated with a deterioration in boost control.

[0054] In this way, a controller can monitor the response time of a boost pressure control system to selected boost pressure deviations triggered by an operator, without referencing a commanded or measured wastegate position. It can then indicate a deterioration of the boost pressure control system and meet OBD test requirements if the monitored response time exceeds a threshold while qualifying vehicle operating conditions are met. In one example, the desired boost pressure is processed through a delay and lag filter using a time constant. A boost pressure deviation is calculated from the processed desired value minus the measured or actual pressure. In another example, the selected boost pressure deviation might include deviations that fall outside an upper or lower limit.In one example, the upper limit is based on a set tolerated under-deviation level, and the lower limit is based on a tolerated over-deviation level, with strong control corrections applied beyond these limits. Qualifying vehicle operating conditions may include a minimum vehicle runtime, a threshold combustion engine temperature, and a minimum intake manifold pressure level. The control system may include further instructions if, in response to the qualifying vehicle operating conditions sufficient to detect a potential defect, a test timer advances when the vehicle runtime, minimum combustion engine temperature, minimum intake manifold pressure, and minimum mass injection level are met.In another example, the control unit, in response to the monitored response time being less than the threshold, can update the monitored response time in a memory of the internal combustion engine control unit and not indicate any degradation of the boost pressure control system. In one example, indicating degradation in response to the monitored response time involves specifying the magnitude of the selected boost pressure deviations once they fall outside an upper or lower limit, without referencing the commanded or measured wastegate position.

[0055] An example of variations in response time during closed-loop boost pressure control in a fault-free boost pressure control system is given with reference to Fig. in Fig. Figure 4 shows a desired boost pressure (Pdes). The desired boost pressure (expected), as processed by a delay and a lag filter, is shown in curve 404 (dashed line with long dashes). Actual boost pressure, as measured by a pressure sensor, is shown in curve 402 (solid line). Pressure is shown on the y-axis and time on the x-axis. As shown in curves 402 and 404, the expected boost pressure matches the actual boost pressure for the majority of the driving cycle.

[0056] In some places, the traces 402 and 404 do not coincide, and these are conditions under which the procedure of Fig. 2A-2B is restricted to reduce misinterpretation of the results. In range 410, for example, when the internal combustion engine is operating at idle, the actual boost pressure (402) responds more slowly to the commanded boost pressure change than during non-idle conditions. Therefore, curves 402 and 404 do not align well in this range. As another example, the actual boost pressure, during selected pedal inputs and outputs, as shown in range 420, briefly exceeds and falls below the setpoint, even though the system is not faulty. Furthermore, under some internal combustion engine operating conditions, such as range 430, the actual boost pressure (402) may be subject to disturbances that the control slowly rejects. In range 410, the vehicle is in a minimum operating state with an even longer lag, which can be prevented by limiting the static boost pressure (at 204 in Fig. 2A) is checked. In the 420 range, the actual boost pressure fluctuates slightly, and these brief, small deviations above and below the limit are detected by checking the upper and lower limits (at 210 in Fig. 2A) blocked. Area 430 is blocked by the minimum pressure test (at 204 in Fig. 2A) is also blocked.

[0057] An exemplary boost pressure control diagnostic test without a defect is now available in the Fig. in Fig. 5 shown. Fig. The changes in vehicle speed (Vspd) are shown in graph 502. Accordingly, the changes in vehicle speed reflect the change in operator torque demand, with torque demand increasing when an operator presses an accelerator pedal to increase vehicle speed, and torque demand decreasing when the operator presses a brake pedal and / or releases the accelerator pedal to decrease vehicle speed. The fuel injection mass in response to the change in torque demand is shown in graph 504. VGT wastegate (WG) settings are shown in graphs 505 (desired) and 506 (measured), which overlap considerably in a non-defective example. In particular, graph 506 shows a degree of WG opening, with the WG opening increasing from top to bottom along the y-axis as boost pressure is released.Boost pressure changes are shown in graphs 508-510, where graph 510 (dashed line) represents the expected boost pressure and graph 508 (solid line) represents the actual boost pressure. The boost pressure deviation (Pdvt, determined as the difference between the desired, delayed, and filtered boost pressure and the actual boost pressure) is shown in graph 512 with respect to an upper limit (Thr_U) and a lower limit (Thr_L). The output of a timer measuring a boost response of a feedback control system is shown in graph 514. A marker indicating deterioration of a boost control system is shown in graph 516. All graphs are shown against time along the x-axis. The deviation event markers d1-d3 represent key points. Fig. 5. The deviation events are the periods below a deviation defect level very short, so that the defect indicator 516 remains at 0.

[0058] An example of a boost pressure control diagnostic with a defect is now available in the Fig. in Fig. 6 shown. Fig. out of Fig. 6 is an equivalent mapping as in Fig. 5 (where identical parameters are named in the same way), except that an error is induced with a slow response, in this example by intentionally slowing down the VGT using a lagging filter with a TC of 5 seconds. Each curve is equivalent to Fig. 5, but with a 600 series number instead of a 500 series number. In this example, the desired VGT wastegate (605) attempts to adjust itself when the operator torque demand changes (604), and the desired boost pressure changes (608). Wastegate settings are commanded to bring the actual boost pressure to the desired boost pressure. The wastegate settings are commanded by a feedback control loop of the internal combustion engine control unit, with the settings being commanded in response to a magnitude of pressure error between the actual and desired boost pressure (not shown).If the pressure deviation (expected - actual) exceeds a range defined by the upper and lower limits, and if other qualifying vehicle operating conditions are met, the procedure monitors the time required by the feedback control loop to bring the actual boost pressure to the desired delayed and filtered boost pressure level. The controller repeats this several times during a driving cycle, whenever an opportunity arises to determine an instance of a feedback control loop response time to a pressure deviation. If the response time for a boost event exceeds the allowable defect level response time for the vehicle model, a deterioration of the boost pressure response time is indicated (616), and a slow boost response is attributed to the deterioration.

[0059] For example, at t1, after a rapid increase in torque demand requiring a rapid increase in fuel injection mass, the VGT wastegate opens in response to the torque demand to reduce boost pressure. However, in this fault example, the VGT wastegate was too slow to fully contain the boost pressure increase, and the pressure deviation exceeded the defined range (between Thr_U and Thr_L). A duration d1, representing the boost response time, is determined between times t1 and t2 (when the pressure deviation was again within the Thr_L limit). The fault indicator 616 only indicates a fault when time d1 reaches a fault level threshold, which has a short duration for event d1 but is sufficient to indicate a fault condition. Event d2 is an even larger deviation example where the deviation timer increases, clearly exceeding the permissible fault level, which occurs at time t3.

[0060] The last course from Fig. 6 (curve 618) shows the test timer, which tracks how long conditions persisted during the journey under which a defect could be detected. Curve 618 only increases if a series of conditions at 204 are met, but most importantly, condition 228 must also be met. In curve 604, the rate of change of the fuel mass is marked by r2, a sharp rise, and r1, a gradual rise. Curve 618 requires a sharp rise from 604 to advance the test timer. It should be noted that the gradual rise r1 occurs when there is still some lag of the VGT-WG, but it is small. Curves 608 and 610 thus overlap at this point, and the deviation 612 lies clearly between the Thr_U and Thr_L limits.The curve of the test timer 618 for the defect case corresponds relatively exactly to the large pressure adjustments, and can therefore be used as an indication that the procedure can distinguish when a defect is possible, since the test timer is for both . Fig. 5 out of 518 (no defect) and Fig. 6 at 618 (defective) advances equivalently.

[0061] The indicator in traces 516 and 616 is shown to illustrate when the procedure detects a fault. Once a fault is detected, the procedure communicates this to the PCM's OBD diagnostic routines, which follow a regulatory procedure involving the activation of a malfunction indicator lamp, communication with diagnostic service tools, updating a usage rate monitoring device for the various OBD tests, and so on. For a given trip, there is no further need for the procedure to continue running for OBD purposes, although continued operation might have some benefit for other functions. Although a fault is detected at t2 in this example, we have continued operation to show that the procedure will detect further faults if the trip continues.

[0062] Therefore, the procedure is not used to test a single turbocharging system component, but rather to diagnose overall system deterioration. While the preceding example uses the VGT and WG as illustrations, this is only to demonstrate a defect. It will be understood that problems with other system components, such as a leak, an incorrectly installed intake manifold, etc., could potentially cause the same slow response.In one example, after detecting a slow charging response, the control system can initiate another monitoring device based on the completion of the monitoring device described above to identify a source for the slow charging response, identifying a component responsible for the slow charging response (and distinguishing it from other actuators of the charging response), and then implementing mitigating measures based on the identified source of the slow charging response.

[0063] In this way, the response time of a closed-loop control system to a pressure deviation can be used to non-intrusively diagnose boost degradation. By correlating the degradation of the boost control with a slow boost response without referencing the command or position of the boost actuators (such as a VGT wastegate), a slow-response boost pressure can be diagnosed accurately and reliably. By measuring the response time of pressure deviations that lie outside a range defined by upper and lower limits, misdiagnoses (including incorrectly reporting that a fault-free system is faulty, or that a faulty system is fault-free) due to differences in the boost response to boost pressure overshoots versus undershoots can be better accounted for.By diagnosing based on response time only when qualifying vehicle operating conditions are met, such as not operating at or near idle, the confidence factor of the results can be increased. Because the test is performed passively, the vehicle's drivability and emissions are not affected. By comparing the response time of a qualified charging event to an empirically determined maximum defect-free charging response time for an exhaustive range of driving conditions, charging degradation can be determined without the need for complex and computationally intensive modeling. Diagnosing charging response degradation for qualified driving conditions ensures compliance with regulatory requirements and allows for the timely resolution of charging-related issues, maintaining the expected driving experience for the vehicle owner.

[0064] An exemplary procedure for a turbocharged internal combustion engine in a vehicle comprises: during the operation of an internal combustion engine with a closed-loop turbocharger charge control system, indicating a deterioration in the response of a boost pressure control system based on the duration of a deviation exceeding a threshold between an expected change in boost pressure and an actual change in boost pressure over a driving cycle without referencing a command or measurement of a variable geometry turbine (VGT) or wastegate.In the preceding example, the method additionally or optionally includes monitoring the vehicle operating conditions and advancing a test timer of a boost response monitoring device when selected operating conditions are confirmed that allow a slow boost response to be detected when boost deterioration is present, wherein the selected vehicle operating conditions include a rate of change of the fuel injection mass that is higher than a threshold rate. In one or all of the preceding examples, the method additionally or optionally further includes indicating the termination of the boost response monitoring device in response to an indication of deterioration and the elapsed threshold time on the test timer.In one or all of the foregoing examples, the internal combustion engine is additionally or optionally operated with closed-loop turbocharging control under conditions other than idle conditions, which includes each of the elapsed threshold vehicle runtime, reaching a threshold combustion engine temperature, and maintaining a threshold intake manifold pressure. In one or all of the foregoing examples, specifying additionally or optionally includes specifying degradation in response to the duration exceeding a threshold duration, and specifying regardless of the wastegate command, even if the wastegate command changes over the driving cycle to dismiss boost pressure disturbances.In one or all of the foregoing examples, the deviation exceeding a threshold additionally or optionally includes a difference between the expected boost pressure and the actual boost pressure that lies outside a range defined by an upper limit and a lower limit, wherein the upper limit is based on a tolerance of permissible undershoot for a nominal boost control system, and the lower limit is based on a tolerance of permissible overshoot for a nominal boost control system. In one or all of the foregoing examples, the method further additionally or optionally includes, in response to the specification, adjusting one or more internal combustion engine operating parameters to increase the throttle intake pressure, wherein the one or more internal combustion engine operating parameters include an intake throttle position, a VGT position, and a wastegate position.In one or all of the foregoing examples, the method further additionally or optionally includes estimating a deviation between the expected change in boost pressure and the actual change in boost pressure, wherein the estimation includes estimating a target boost pressure based on the operator torque requirement; processing the target boost pressure via a fixed delay and a fixed lag filter parameter of the boost pressure control system; and calculating the deviation as a difference between the processed target boost pressure and a measured boost pressure.

[0065] Another exemplary procedure involves monitoring the response time of a boost pressure control system to selected boost pressure deviations triggered by an operator, regardless of whether a commanded or measured wastegate position is referenced; and indicating a deterioration of the boost pressure control system in response to the monitored response time exceeding a threshold duration while qualifying vehicle operating conditions are met. In the above example, the selected boost pressure deviations additionally or optionally include boost pressure deviations between an expected boost pressure and an actual boost pressure that are greater than an upper limit or less than a lower limit.In one or all of the above examples, the selected boost pressure deviations are additionally or optionally based on the expected boost pressure, which is calculated from the desired boost pressure after processing it through a filter with a fixed delay and lag with a fixed parameter time constant. In one or all of the above examples, the upper limit is additionally or optionally based on a tolerance of the permissible undershoot for a nominal boost pressure control system, and the lower limit is based on a tolerance of the permissible overshoot for the nominal boost pressure control system. In one or all of the above examples, the qualifying vehicle operating conditions additionally or optionally include a minimum vehicle running time, a threshold combustion engine temperature, and a minimum intake manifold pressure level.In one or all of the foregoing examples, the method further comprises, additionally or optionally, in response to the failure to meet the vehicle operating conditions, continuing to monitor the response time until either deterioration is indicated or the qualified observation time has elapsed. In one or all of the foregoing examples, the method further comprises, additionally or optionally, in response to the monitored response time being less than the threshold duration, updating the monitored response time in a memory of an internal combustion engine control unit and indicating no deterioration of the boost pressure control system.In one or all of the above examples, additionally or optionally, indicating deterioration in response to the monitored response time includes indicating deterioration regardless of the magnitude of the selected boost pressure deviations once the threshold duration has elapsed and regardless of the referencing of the commanded or measured wastegate position.

[0066] Another exemplary vehicle system comprises: an internal combustion engine; a turbocharger, including an intake compressor driven by an exhaust turbine; a wastegate valve arranged in a wastegate coupled via the exhaust turbine; a timer; and a controller with computer-readable instructions stored in non-volatile memory to: set a position of the wastegate valve and initiate the timer in response to a change in the required boost pressure and disturbances detected by feedback; monitor a duration elapsed on the timer to complete a pressure deviation correction equal to the requested difference between the expected and actual boost pressure after setting.In one or all of the above examples, the control system additionally or optionally includes instructions to monitor the duration in response to the fulfillment of qualifying vehicle operating conditions, including a minimum vehicle running time, a threshold combustion engine temperature estimated by an internal combustion engine temperature sensor, and a minimum intake manifold pressure level estimated by an intake manifold pressure sensor. In one or all of the above examples, the control system additionally or optionally includes instructions to continue monitoring in response to the failure to fulfill the vehicle operating conditions until either deterioration is indicated or a permissible observation time is exceeded.In one or all of the foregoing examples, the control additionally or optionally includes instructions for processing a desired boost pressure to form the expected pressure via a delay and a time constant parameter lag filter with a time constant parameter; and calculating a boost pressure deviation as a difference between the expected boost pressure and the actual boost pressure, wherein the specification includes a specification of deterioration if the boost pressure deviation is outside a range formed by an upper limit and a lower limit, wherein the upper limit is based on a tolerance of permissible undershooting for a nominal system, and the lower limit is based on a tolerance of permissible overshooting for a nominal system.

[0067] In another description, a procedure for a turbocharged internal combustion engine comprises: over a driving cycle, estimating an instantaneous pressure deviation between an actual boost pressure and an expected boost pressure; in response to the instantaneous pressure deviation being higher than a threshold level, monitoring a duration for which the instantaneous pressure deviation remains higher than the threshold level, and comparing the monitored duration with the duration of a last threshold-exceeding pressure deviation in the driving cycle.In response to each monitored duration of the instantaneous pressure deviation exceeding a threshold being greater than the monitored duration of the last pressure deviation exceeding a threshold in the driving cycle, and the monitored duration of the instantaneous pressure deviation exceeding a threshold being greater than a threshold duration, this indicates a degraded response time (or slow boost response time) of a boost control system coupled to the turbocharged internal combustion engine. In a further representation, the instantaneous pressure deviation exceeding a threshold level additionally or optionally includes the instantaneous pressure deviation being higher than an upper deviation limit or lower than a lower deviation limit.In another representation, monitoring the duration additionally or optionally includes starting or advancing a deviation timer in response to the instantaneous pressure deviation exceeding the threshold level. In yet another representation, additionally or optionally, if the monitored duration of the instantaneous pressure deviation exceeding a threshold is less than the monitored duration of the last pressure deviation exceeding a threshold in the driving cycle, the deviation timer is reset, and the monitored duration of the instantaneous pressure deviation exceeding a threshold is not stored in the combustion engine control unit's memory, while the monitored duration of the last pressure deviation exceeding a threshold is retained in the combustion engine control unit's memory.In another representation, estimating the instantaneous pressure difference between the actual boost pressure and the expected boost pressure is a response to the fulfillment of qualifying vehicle operating conditions, where the qualifying vehicle operating conditions include a minimum vehicle run time, a threshold combustion engine temperature, and a minimum intake manifold pressure level. In yet another representation, the actual boost pressure is derived based on a throttle inlet pressure, and the expected boost pressure is estimated by processing a commanded boost pressure, where the commanded boost pressure is based on an operator torque requirement.In another embodiment, the turbocharged internal combustion engine includes a turbocharger having an exhaust turbine and a wastegate coupled to the turbine, wherein the turbine is a variable geometry turbine (VGT), wherein the method further comprises: commanding a VGT and / or a wastegate based on the operator torque requirement to reduce a difference between the actual boost pressure and the commanded boost pressure, and wherein specifying a degraded response time is performed independently of the commanded VGT and / or wastegate position.In another representation, in response to the vehicle operating conditions being met and a calculated rate of change of the fuel injection mass being higher than a threshold, a test timer, distinct from the deviation timer, is started or advanced. The test timer continues to advance until a qualified test time has elapsed on the test timer and the monitored duration of the instantaneous pressure deviation exceeding a threshold is greater than the threshold duration. Then, a test time is indicated as complete, and the test timer is reset. In another representation, in response to the monitored duration of the instantaneous pressure deviation exceeding a threshold being less than the threshold duration and the test time on the test timer being complete, no deterioration of the boost response time is indicated.

[0068] It should be noted that the control and estimation routines contained herein can be used with various internal combustion engine and / or vehicle system configurations. The control procedures and routines disclosed herein can be stored as executable instructions in non-volatile memory and can be executed by the control system, which includes the controller in combination with the various sensors, actuators, and other internal combustion engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, various illustrated operations, steps, and / or functions can be performed in the illustrated sequence or in parallel, or in some cases, omitted.Similarly, the processing sequence is not strictly necessary to achieve the features and advantages of the exemplary embodiments described here, but is provided to facilitate illustration and description. One or more of the illustrated actions, processes, and / or functions can be performed repeatedly, depending on the specific strategy employed. Furthermore, the described actions, processes, and / or functions can graphically represent code that is to be programmed into non-volatile memory of the computer-readable storage medium in the internal combustion engine control system, with the described actions being executed by carrying out the instructions in a system that includes the various internal combustion engine hardware components in combination with the electronic control unit.

[0069] It is understood that the interpretations and routines disclosed herein are exemplary in nature and that these specific embodiments are not to be interpreted in a restrictive sense, as numerous variations are possible. For example, the foregoing technology can be applied to V-6, I-4, I-6, V-12, 4-cylinder boxer, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0070] The following claims describe, in particular, certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims should be understood as including one or more such elements and neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application.Such patent claims shall also be considered as included in the subject matter of the present disclosure, irrespective of whether they have a broader, narrower, the same or a different scope compared to the original patent claims.

Claims

[1] Diagnostic procedure for a turbocharged internal combustion engine in a vehicle, comprising: Activating a monitoring device and adjusting an actuator during the operation of an internal combustion engine with a closed-loop turbocharger boost control system by a controller, and providing an indication of deterioration by the controller based on the duration of an actual deviation exceeding a threshold deviation level between an expected change in boost pressure and an actual change in boost pressure over a driving cycle without referencing a command or measurement of a variable geometry turbine (VGT) or wastegate, where the internal combustion engine is operated by the control system with a closed-loop turbocharging control under conditions other than idle conditions, which includes any of the passage of a threshold vehicle running time, reaching a threshold combustion engine temperature and maintaining a threshold intake manifold pressure. [2] Diagnostic method according to claim 1, further comprising monitoring the vehicle operating conditions and advancing a test timer of a charge response monitoring device when selected vehicle operating conditions are confirmed by the control unit, which enable a slow charge response to be detected when charge deterioration is present, wherein the selected vehicle operating conditions include a rate of change of the fuel injection mass that is higher than a threshold rate. [3] Diagnostic method according to claim 2, further comprising indicating the completion of the charging reaction monitoring device in response to a deterioration indication and the elapse of a threshold time on the test timer. [4] Diagnostic method according to claim 1, wherein the indication of deterioration is made in response to the fact that the duration is higher than a threshold duration. [5] Diagnostic method according to claim 1, wherein the deviation exceeding a threshold includes a difference between the expected boost pressure and the actual boost pressure which lies outside a range defined by an upper limit and a lower limit. [6] Diagnostic method according to claim 5, wherein the upper limit is based on a tolerance of undershooting and the lower limit is based on a tolerance of permissible overshooting for the nominal charging control system. [7] Diagnostic method according to claim 1, further comprising, in response to the specification, adjusting one or more internal combustion engine operating parameters to increase the throttle inlet pressure, wherein the one or more internal combustion engine operating parameters include an intake throttle position, a VGT position and a wastegate position. [8] Diagnostic method according to claim 1, further comprising estimating a deviation between the expected change in boost pressure and the actual change in boost pressure, wherein the estimation includes: Estimating a target boost pressure based on operator torque requirements: Processing the target boost pressure via the control unit and one fixed delay and one fixed lag filter parameter each; and Calculating the deviation as a difference between the processed target boost pressure and a measured boost pressure. [9] Diagnostic procedures for a turbocharged internal combustion engine in a vehicle, comprising: by a control system, executing a monitoring device, adjusting an actuator, and monitoring a response time to selected boost pressure deviations triggered by an operator, independent of referencing a commanded or measured wastegate position; and In response to the monitored response time exceeding a threshold duration while qualifying vehicle operating conditions are met, the control system generates an indication of deterioration. wherein generating the deterioration display in response to the monitored response time includes displaying a deterioration regardless of the size of the selected boost pressure deviations once the threshold duration has elapsed, and without referencing the commanded or measured wastegate position. [10] Diagnostic method according to claim 9, further comprising, in response to the fact that the monitored response time is less than the threshold duration, updating the monitored response time in a memory of the internal combustion engine control and indicating no deterioration. [11] Vehicle system, comprising: an internal combustion engine; a turbocharger, including an intake compressor driven by an exhaust turbine; a wastegate valve that is arranged in a wastegate coupled via the exhaust turbine; a timer; and a controller with computer-readable instructions stored in non-volatile memory for: In response to a change in the required boost pressure and disturbances detected by feedback, the wastegate valve is set to a position and the timer is initiated; Monitoring the time elapsed on the timer to complete a pressure deviation correction, which corresponds to a difference between an expected boost pressure and an actual boost pressure after adjustment; and Informing the driver of a deteriorated charging response time based on the monitored duration. [12] System according to claim 11, wherein the control includes further instructions for: Monitoring the duration in response to the fulfillment of qualifying vehicle operating conditions, including a minimum vehicle running time, a threshold combustion engine temperature estimated via an internal combustion engine temperature sensor, and a minimum intake manifold pressure level estimated by an intake manifold pressure sensor. [13] System according to claim 12, wherein the control includes further instructions for: In response to the fact that the vehicle operating conditions are not met, monitoring will continue until either a deterioration is indicated or a permissible observation time has been exceeded. [14] System according to claim 11, wherein the control includes further instructions for: Calculating a boost pressure deviation as a difference between the expected boost pressure and the actual boost pressure; where the specification includes a specification of deterioration if the boost pressure deviation is outside a range formed by an upper limit and a lower limit, the upper limit being based on a tolerance of permissible undershooting for a nominal system, and the lower limit being based on a tolerance of permissible overshooting for the nominal system.

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