Method and system for EGR system

Abstract

The present disclosure provides a method and system for an EGR system. Methods and systems are provided for an exhaust gas recirculation (EGR) system. In one example, a method includes determining a current EGR valve offset and a historical EGR valve offset, and comparing the current EGR valve offset to the historical EGR valve offset to determine the presence of an EGR leak.

Description

Technical Field

[0001] The present description generally relates to a diagnostic routine for an EGR system for a vehicle. Background Art

[0002] Engine systems can utilize the recirculation of exhaust gas from the engine exhaust system to the engine intake system, a process known as exhaust gas recirculation (EGR), to reduce emissions. The EGR valve can be controlled to achieve the desired intake dilution for given engine operating conditions. Traditionally, the amount of low-pressure EGR (LP-EGR) and / or high-pressure EGR (HP-EGR) directed through the EGR system can be measured and adjusted based on engine speed, engine temperature, and load during engine operation to maintain the desired combustion stability of the engine while providing emissions and fuel economy benefits. EGR effectively cools the combustion chamber temperature, thereby reducing NO x formation.

[0003] In some existing embodiments of the EGR system, EGR delivery can be measured via a fixed orifice and a pressure drop sensed across the orifice. The orifice pressure drop can be measured by a differential pressure sensor or two separate pressure sensors (one pressure sensor on each side of the orifice). Orifice EGR flow measurement can be performed by characterizing the relationship between flow and orifice pressure drop. The relationship can be stored in a memory and retrieved during future EGR flow conditions to adjust the flow rate of the EGR measurement. The flow rate of the EGR measurement can then be used by the controller to adjust the engine airflow, the combustion rate of the fuel / air mixture in the cylinder, the engine output torque, and used as a feedback signal in a closed-loop EGR flow controller configuration, where the EGR flow is modulated by a valve separate from the fixed orifice.

[0004] Other examples of EGR systems include measuring the delivered EGR flow by measuring or estimating the pressure drop across the EGR control valve. The EGR control valve measurement can characterize the relationship between the flow and the orifice pressure drop. The values ​​can be stored and used to adjust conditions similar to those described above. The EGR flow measurement in any of these configurations can depend on the accuracy of the pressure sensor and / or the position sensor of the EGR valve. Although there are diagnostics for the pressure sensor, it is still desirable to diagnose the position sensor. In addition, since the duty cycle of the EGR valve can be based on feedback from the position sensor, it is desirable to recalibrate the position sensor based on the diagnosis. Summary of the invention

[0005] In one example, the above problem can be solved by a method for operating an exhaust gas recirculation (EGR) system, the method comprising: applying a cooler pressure model to calculate a cooler pressure drop based on engine operating parameters and EGR flow; and diagnosing an EGR pressure (EGRP) sensor based on a comparison of an EGR pressure (EGRP) sensor reading with a manifold air pressure (MAP) sensor reading and the cooler pressure drop. In this way, diagnosis of the hot side EGRP sensor can be performed.

[0006] As an example, the EGR system may include multiple diagnostic routines for determining the condition of the EGRP sensor. The routines may be executed individually or in concert to verify the condition of the EGRP sensor. By doing so, the EGR mass flow to the engine may be equal to the desired amount, which may improve engine performance and reduce emissions.

[0007] It should be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Advantages described herein will be more fully understood by reading examples of embodiments referred to herein as detailed descriptions when read alone or with reference to the accompanying drawings, in which:

[0009] Figure 1 shows a schematic diagram of an engine included in a hybrid vehicle;

[0010] Figure 2 A first routine for diagnosing an exhaust gas recirculation pressure (EGRP) sensor according to an embodiment of the present disclosure is shown;

[0011] Figure 3 A second routine for diagnosing an exhaust gas recirculation pressure (EGRP) sensor according to an embodiment of the present disclosure is shown;

[0012] Figure 4 A third routine for diagnosing an exhaust gas recirculation pressure (EGRP) sensor according to an embodiment of the present disclosure is shown;

[0013] Figure 5 A fourth routine for diagnosing an exhaust gas recirculation pressure (EGRP) sensor according to an embodiment of the present disclosure is shown;

[0014] Figure 6A method for determining whether EGR valve deviation is occurring simultaneously with misfire according to an embodiment of the present disclosure is shown;

[0015] Figure 7 A method for determining historical EGR valve offset according to an embodiment of the present disclosure is shown; and

[0016] Figure 8 An engine operating sequence for comparing EGR valve excursion to historical excursions and determining whether maintenance is desired is shown according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] The following description relates to systems and methods for an exhaust gas recirculation (EGR) system. In one example, the EGR system is configured to direct exhaust gas back to the engine, such as Figure 1 The EGR system may include a valve and one or more sensors for metering EGR flow to a determined amount based on operating conditions. Figures 2 to 5 A procedure for diagnosing the condition of one or more sensors is shown in FIG. Figure 6 to Figure 7 A procedure for determining the offset of a valve of an EGR system is shown in FIG. Figure 8 An operational sequence is shown that graphically illustrates comparing a current valve offset to a historical EGR valve offset and determining whether the EGR valve offset is causing an undesirable amount of EGR leakage.

[0018] Figure 1An example configuration with relative positioning of various components is shown. In at least one example, if it is shown as directly contacting each other or directly connected, such elements can be referred to as direct contact or direct connection, respectively. Similarly, in at least one example, the elements shown as adjacent or adjacent to each other can be adjacent or adjacent to each other, respectively. As an example, components that are coplanarly contacted with each other can be referred to as coplanar contact. As another example, in at least one example, elements that are positioned apart from each other with only space between them and no other components can be referred to as such. As another example, elements that are shown as above / below each other, on both sides opposite to each other, or on the left / right side of each other can be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the vertex of the element can be referred to as the "top" of the component, and the bottommost element or the bottommost point of the element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings, and are used to describe the positioning of the elements of the accompanying drawings relative to each other. Therefore, in one example, the element shown as above other elements is located directly above other elements. As yet another example, the shapes of elements depicted within the drawings may be referred to as having these shapes (e.g., such as being round, straight, planar, curved, rounded, chamfered, angled, etc.). In addition, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, elements shown as being within another element or shown as being outside another element may be referred to as such. It should be understood that one or more components referred to as "substantially similar and / or identical" differ from each other according to manufacturing tolerances (e.g., within a deviation of 1% to 5%).

[0019] Figure 1 A schematic depiction of a hybrid vehicle system 6 that may derive propulsion power from an engine system 8 and / or an onboard energy storage device is shown. An energy conversion device, such as a generator, may be operated to absorb energy from vehicle motion and / or engine operation and then convert the absorbed energy into an energy form suitable for storage by the energy storage device.

[0020] The engine system 8 may include an engine 10 having a plurality of cylinders 30. The engine 10 includes an engine intake 23 and an engine exhaust 25. The engine intake 23 includes an intake throttle 62 fluidly coupled to an engine intake manifold 44 via an intake passage 42. Air may enter the intake passage 42 via an air filter 52. The engine intake manifold 44 may also include a manifold absolute pressure (MAP) sensor 95. The engine exhaust 25 includes an exhaust manifold 48 leading to an exhaust passage 35 that directs exhaust gas to the atmosphere. The engine exhaust 25 may include at least one emission control device 70 mounted in a close-coupled position or a distal underbody position. The emission control device 70 may include a three-way catalyst, a lean NOx trap, a particulate filter, an oxidation catalyst, etc. It should be understood that other components such as various valves and sensors may be included in the engine, as described in further detail herein. In some embodiments in which the engine system 8 is a supercharged engine system, the engine system may also include a supercharging device, such as a turbocharger (not shown).

[0021] In an example of the present disclosure, emission control device 70 is a particulate filter 70. In one example, particulate filter 70 is a gasoline particulate filter. In another example, particulate filter 70 is a diesel particulate filter.

[0022] Engine system 8 also includes a turbocharger having a compressor 82 and a turbine 84. Compressor 82 and turbine 84 are mechanically coupled via shaft 86. Turbine 84 may be driven by exhaust gas flowing through exhaust passage 35. The exhaust gas may rotate a rotor of turbine 84, which may rotate shaft 86, thereby causing rotation of a rotor of compressor 82. Compressor 82 is configured to receive and compress intake air.

[0023] The engine system 8 also includes an exhaust gas recirculation (EGR) system 130. Figure 1 In the example of , EGR system 130 is a high pressure EGR system in which exhaust gas is extracted from a location of engine exhaust port 25 upstream of turbine 84. EGR system 130 includes an EGR valve 134 disposed upstream of heat exchanger 138 relative to the direction of exhaust gas flow in EGR passage 132.

[0024] The EGR system 130 also includes a first pressure sensor 135 (referred to herein as exhaust pressure (EXP) sensor 135), a second pressure sensor 136 (referred to herein as EGR pressure (EGRP) sensor 136), and a temperature sensor 139. Relative to the direction of exhaust flow, the EXP sensor 135 can be arranged upstream of the EGR valve 134, while the EGRP sensor 136 can be arranged downstream of the EGR valve. The temperature sensor 139 can be arranged downstream of the heat exchanger 138. Each of the EXP sensor 135, the EGRP sensor 136, and the temperature sensor 139 can be configured to provide feedback to the controller 12. As shown, the EGR system 130 is a high-pressure EGR system without a fixed orifice differential pressure sensor. In one example, the EGR system 130 is a differential pressure on valve (DPOV) EGR system 130, in which the pressure differential is determined via feedback from the EXP sensor 135 and the EGRP sensor 136.

[0025] EGR valve position sensor 137 may be configured to provide feedback to controller 12 regarding the position of EGR valve 134. In some examples, the accuracy of EGR valve position sensor 137 and / or EGRP sensor 136 may degrade over time. This may cause the EGR flow rate to differ from the requested amount, which may reduce engine performance. A routine for diagnosing a condition of EGRP sensor 136 is included herein.

[0026] In one example, the heat exchanger 138 can be a liquid-to-liquid or air-to-liquid cooler. The heat exchanger 138 can be configured to receive coolant from a cooling system of the hybrid vehicle 6, such as an engine cooling system or other similar cooling system. The heat exchanger 138 (interchangeably referred to herein as a cooler) is arranged downstream of the EGRP sensor 136 relative to the direction of EGR flow. In one example, the EGR system 130 including the EGR valve 134 upstream of the heat exchanger 138 is a hot side EGR system configuration.

[0027] Additionally or alternatively, heat exchanger 138 may include a cooling system that is separate from other cooling systems of hybrid vehicle 6. In some examples, a bypass passage may be included in EGR system 130, wherein the bypass passage is configured to flow pressurized exhaust gas around heat exchanger 138 during conditions where cooling may not be desired. In one example, cooling may not be desired during conditions where engine temperature is below a desired temperature, such as during a cold start.

[0028] exist Figure 1In the example of FIG. 1 , hybrid vehicle 6 also includes a low-pressure (LP) EGR passage 142. LP-EGR passage 142 is configured to transfer exhaust gas from downstream of turbine 84 to a portion of intake passage 42 upstream of compressor 82. Additionally or alternatively, in some examples, hybrid vehicle 6 may be configured without LP-EGR passage 142 without departing from the scope of the present disclosure.

[0029] The hybrid vehicle 6 may also include a control system 14. The control system 14 is shown as receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As one example, the sensors 16 may include an exhaust gas sensor 126, a temperature sensor 128, and a pressure sensor 129 located upstream of an emission control device. The sensors 16 may also include a barometric pressure (BP) sensor (e.g., a barometer) 98. Other sensors such as additional pressure sensors, temperature sensors, air-fuel ratio sensors, and composition sensors may be coupled to various locations in the vehicle system 6. As another example, the actuator may include a throttle 62.

[0030] The controller 12 may be configured as a conventional microcomputer including a microprocessor unit, input / output ports, read-only memory, random access memory, keep-alive memory, a controller area network (CAN) bus, etc. The controller 12 may be configured as a powertrain control module (PCM). The controller may transition between a sleep mode and a wake-up mode to obtain additional energy efficiency. The controller may receive input data from various sensors, process the input data, and trigger actuators in response to the processed input data based on instructions or codes programmed therein corresponding to one or more programs.

[0031] In some examples, the hybrid vehicle 6 includes multiple torque sources available to one or more wheels 59. In other examples, the vehicle 6 is a conventional vehicle with only an engine or an electric vehicle with only one or more motors. In the example shown, the vehicle 6 includes an engine 10 and a motor 51. The motor 51 can be a motor or a motor / generator. When one or more clutches 56 are engaged, the crankshaft of the engine 10 and the motor 51 can be connected to the wheels 59 via a transmission 54. In the depicted example, a first clutch 56 is provided between the crankshaft and the motor 51, and a second clutch 56 is provided between the motor 51 and the transmission 54. The controller 12 can send a signal to the actuator of each clutch 56 to engage or disengage the clutch so as to connect or disconnect the crankshaft with the motor 51 and the components connected thereto, and / or connect or disconnect the motor 51 with the transmission 54 and the components connected thereto. The transmission 54 can be a gearbox, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

[0032] The electric machine 51 receives power from the traction battery 61 to provide torque to the wheels 59. The electric machine 51 may also act as a generator to provide power to charge the battery 61, such as during braking operations.

[0033] Now go to Figure 2 , Figure 2 A method 200 for diagnosing an EGRP sensor of an EGR system via a first diagnostic routine is shown. Instructions for executing method 200 and the remaining methods included herein may be executed by a controller based on instructions stored on a memory of the controller and in conjunction with sensors of the engine system (such as those described above with reference to FIG. Figure 1 The controller may use engine actuators of the engine system to adjust engine operation according to the method described below.

[0034] In one example, method 200 and the remaining methods included herein may be combined with Figure 1 For example, the diagnosis of the EGRP 136 may be performed via the method described herein. The diagnostics of the procedures of the method included herein may also include other sensors and actuators of the EGR system as well as Figure 1 The vehicle system includes a MAP sensor 95 , an EXP sensor 135 , a temperature sensor 139 , and an EGR valve 134 .

[0035] Method 200 begins at 202 and includes monitoring cooler pressure drop at various operating points. The cooler pressure drop (e.g., the pressure difference across the cooler) may be determined based on feedback from a pressure sensor upstream of the cooler (e.g., an EGRP sensor) and a pressure sensor downstream of the cooler (e.g., a MAP sensor 95). Additionally or alternatively, the cooler pressure drop may be determined based on a coolant temperature in the cooler and a temperature of the EGR exiting the cooler. The operating points at which the cooler pressure drop is located may include two or more of the following: idle load, low load, high load, intermediate loads between low load and high load, vehicle speed change rate, vehicle towing conditions, coasting events, and other similar operating parameters.

[0036] The chiller pressure model can be used to estimate the chiller pressure drop at different operating points based on empirically collected data. The chiller pressure model can estimate the chiller fouling over time based on the collected data.

[0037] At 204, method 200 may include mapping the chiller pressure drop. The chiller pressure drop may be stored in a multi-input lookup table in a memory of the controller. The inputs may include different operating points, where the output may include the chiller pressure drop.

[0038] At 206 , method 200 may include sensing pressure between the EGR valve and the intake port. In one example, the pressure may be sensed by an EGRP sensor located between the EGR valve and the cooler.

[0039] At 208, method 200 may include determining whether the EGRP sensor reading is equal to a threshold. In one example, the threshold is equal to the sum of MAP and cooler pressure drop. In some examples, the EGRP sensor reading may additionally or alternatively be compared to a range based on the threshold. For example, the range may be based on the threshold. + 5%. As discussed above, the cooler pressure drop is monitored at different operating points. Therefore, the threshold value is a dynamic value that changes based on the current operating point of the vehicle.

[0040] If the EGRP sensor reading is equal to or within a threshold, method 200 may include determining that the EGRP sensor is not degraded at 210. Therefore, the EGR flow estimation based on feedback from the EGRP sensor may be accurate, and the EGRP sensor feedback may not be modified.

[0041] If the EGRP sensor is not equal to the threshold or is outside the threshold range, at 212 , method 200 may include determining that the EGRP sensor is degraded.

[0042] At 214 , method 200 may include activating an indicator.

[0043] At 216 , method 200 may include applying a correction value. The correction value may be applied to the EGRP sensor reading, which may provide a more accurate estimate of EGR flow.

[0044] In some examples, additionally or alternatively, activating the indicator light may also include requesting service and / or replacement of the EGRP sensor if the EGRP sensor reading is out of range by a determined value (eg, 10% outside of a lower or upper range limit).

[0045] Now go to Figure 3 , Figure 3 A method 300 for diagnosing an EGRP sensor when the EGR valve is closed is shown. At 302, method 300 may include determining whether the EGR valve is closed. The EGR valve may be determined to be closed based on feedback from a MAP sensor, an EGRP sensor, etc. Additionally or alternatively, the EGR valve may be closed based on engine operating conditions during which EGR is not needed.

[0046] If the EGR valve is not closed, Figure 4 Method 400 for diagnosis.

[0047] If the EGR valve is closed, method 300 may include receiving MAP sensor feedback at 304. The MAP sensor may provide an indication of manifold pressure.

[0048] At 306 , method 300 can include receiving EGRP feedback.

[0049] At 308 , method 300 may include determining if MAP sensor feedback is equal to EGRP feedback. When the EGR valve is closed, readings of the MAP sensor and the EGRP sensor may be equal.

[0050] Additionally or alternatively, the MAP sensor reading and the EGRP sensor reading may be compared to a mapped cooler pressure drop. For example, the cooler may be contaminated or include constraints therein that may affect the comparison between the MAP sensor reading and the EGRP sensor reading. Thus, in some embodiments, a cooler pressure model may be used during the diagnostic routine of method 300.

[0051] If the MAP sensor feedback is equal to the EGRP sensor feedback, then at 310 , method 300 may include determining that the EGRP sensor is not degraded. Adjustments to the EGRP sensor feedback may not be initiated.

[0052] If the MAP sensor feedback is not equal to the EGRP sensor feedback, at 312 , method 300 may include determining that the EGRP sensor is degraded.

[0053] At 314 , method 300 may include activating an indicator.

[0054] At 316 , method 300 may include applying a correction value. The correction value may be applied to the EGRP sensor reading, which may provide a more accurate estimate of EGR flow.

[0055] Now go to Figure 4 , Figure 4 A method 400 is shown for diagnosing an EGRP sensor when the EGR valve is open and EGR is flowing to the engine. The method 400 proceeds to Figure 3 Method 300 begins at 402 after a NO at 302 . At 402 , method 400 may include receiving MAP sensor feedback.

[0056] At 404 , method 400 may include receiving EGRP sensor feedback.

[0057] At 406, method 400 may include determining a calibration factor based on the current speed and load. In one example, the EGRP sensor reading and the MAP sensor reading track each other along a quadratic curve. However, at certain speeds and loads, the EGRP sensor reading may deviate from the quadratic curve and the MAP sensor reading. The calibration factor may account for the deviation such that the sum of the calibration factor and the MAP sensor reading equals the EGRP sensor reading when the EGRP sensor is not degraded. In one example, the calibration factor is equal to or based on a cooler pressure drop. Additionally or alternatively, the calibration factor may be empirically determined based on deviations of monitored EGRP sensor readings from MAP sensor readings during different engine speeds and loads.

[0058] At 408, method 400 may include determining whether the difference between the MAP reading and the EGRP reading is within a calibration factor of zero. In other words, the difference between the MAP reading and the EGRP reading is within a calibration factor of zero. + Calibration factors are compared.

[0059] If the difference is equal to zero or within a calibration factor to zero, method 400 may include determining that the EGRP sensor is not degraded at 410. Adjustments to the EGRP sensor feedback may not be initiated.

[0060] If the difference is not within the calibration factor to zero, at 412 , method 400 may include determining that the EGRP sensor is degraded.

[0061] At 414 , method 400 may include activating an indicator.

[0062] At 416 , method 400 may include applying a correction value. The correction value may be applied to the EGRP sensor reading, which may provide a more accurate estimate of EGR flow.

[0063] Now go to Figure 5 , Figure 5 A method 500 for diagnosing an EGRP sensor when an EGR valve is open beyond a threshold position is shown. The method 500 begins at 502 and includes determining whether the EGR valve is open beyond a threshold position. In one example, the threshold position may correspond to a position where the EGR valve is at least 50%, or at least 70%, or at least 80%, or at least 90% open. Thus, the threshold position may include where the EGR valve is closed to a fully open position rather than a fully closed position.

[0064] If the EGR valve is not open beyond the threshold position, at 504, method 500 may include not using the EGRP / EXP pressure ratio to diagnose the EGRP sensor. In one example, if the EGR valve is open but not open beyond the threshold position, the EGRP / EXP pressure ratio may be used. Figure 4 If the EGR valve is closed, the diagnostic procedure of method 400 may be used. Figure 3 The diagnostic procedure of method 300 is used to diagnose EGRP.

[0065] If the EGR valve is open beyond a threshold position, method 500 may include receiving EXP sensor feedback at 506. The EXP sensor may be positioned upstream of the EGR valve relative to the direction of EGR flow.

[0066] At 508, method 500 can include receiving EGRP feedback.

[0067] At 510 , method 500 may include determining an EGRP / EXP ratio.

[0068] At 512 , method 500 may include determining whether the EGRP / EXP ratio is equal to 1. In some examples, additionally or alternatively, it may be determined whether the EGRP / EXP ratio is within a range of 1 (eg, within 5% of 1).

[0069] If the EGRP / EXP ratio is equal to 1, then at 514 , method 500 may include determining that the EGRP sensor is not degraded. Adjustments to the EGRP sensor feedback may not be initiated.

[0070] If the EGRP / EXP ratio is not equal to 1, at 516 , method 500 may include determining that the EGRP sensor is degraded.

[0071] At 518 , method 500 may include activating an indicator.

[0072] At 520 , method 500 may include applying a correction value. The correction value may be applied to the EGRP sensor reading, which may provide a more accurate estimate of EGR flow.

[0073] In this way, multiple routines may be used to diagnose the accuracy of the feedback provided by the EGRP sensor. The routines may be cross-checked against each other to verify that the diagnosis of the EGRP sensor is correct. Two or more routines may be performed to determine the validity and / or accuracy of the condition of the EGRP sensor. By doing so, the EGR mass flow rate may be closer to a desired value, which may enhance engine combustion efficiency and reduce emissions.

[0074] Now go to Figure 6 , Figure 6 A method 600 is shown for determining EGR valve deviation during one or more driving cycles. The method 600 also includes determining whether the EGR valve deviation is causing engine misfire.

[0075] Method 600 begins at 602, which includes determining whether a keep alive memory (KAM) of a controller is being reset. In one example, when a KAM reset is active, memory stored therein may be cleared.

[0076] If KAM reset is active, at 604 , method 600 may include not monitoring EGR leak through the EGR valve.

[0077] If KAM reset is not active, then at 606, method 600 may include determining current operating conditions. Current operating conditions may be operating conditions for the current drive cycle. Current operating conditions may include mass air flow, manifold pressure, engine load, engine speed, EGR flow rate, and air-fuel ratio.

[0078] At 608, method 600 may include sensing a determined number of valve offset samples during the current driving cycle. The determined number of valve offset samples may be a fixed number or a dynamic number. The dynamic number may be adjusted based on current operating conditions, EGR valve position, etc. For example, at least one offset sample may be sensed for each EGR valve position used during the current driving cycle. The offset may be determined based on a comparison between a requested EGR flow rate and an actual EGR flow rate. If the actual EGR flow rate is less than the requested EGR flow rate, the EGR valve offset may be a negative value, indicating that less EGR is flowing than requested. If the actual EGR flow rate is greater than the requested EGR flow rate, the EGR valve offset may be a positive value, indicating that more EGR is flowing than requested. The fixed number may be equal to one sample per EGR valve position, two samples per EGR valve position, etc. If two samples are requested per position, one sample may be collected immediately upon entering the position and another sample may be collected before leaving the position.

[0079] In one example, additionally or alternatively, the offset may be based at least in part on a cooler pressure model and / or an EGRP / EXP ratio. For example, the magnitude of the offset may be based on the cooler pressure model and the EGRP / EXP ratio. For example, if the EGRP / EXP ratio is equal to 1 during a partially open position of the EGR valve, an EGR leak may exist. The commanded EGR position may be adjusted to a more closed position to account for the EGR leak. The commanded EGR position may be adjusted until the EGRP / EXP ratio is equal to a desired value.

[0080] At 610, method 600 may include determining whether the drive cycle is complete. If the engine is turned off due to the ignition key being turned or the ignition button being pressed, the drive cycle is complete. Additionally or alternatively, if start / stop is activated, the drive cycle may be complete.

[0081] If the drive cycle is not complete, method 600 may continue to monitor operating conditions and sense valve offset samples. If the drive cycle is complete, at 612, method 600 may include calculating an average offset for the drive cycle. The average offset may include positive and negative values. Additionally or alternatively, to determine an average EGR leakage through the EGR valve due to EGR valve position offset, the average offset may include only positive values.

[0082] At 614, method 600 may include comparing the average offset to a historical offset average. The historical offset average may be based on an average offset of offsets collected during previous drive cycles. Figure 7 Describes history offset in more detail.

[0083] At 616, method 600 may include determining whether the average offset is less than or equal to the historical offset average. If the average offset is less than or equal to the historical offset average, then at 618, method 600 may include determining that there is no EGR leak. Therefore, diagnostics may be performed. Additionally or alternatively, the historical offset average may be updated based on the average offset determined during the driving cycle of method 600.

[0084] If the average deviation is not less than or equal to the historical deviation average (e.g., greater than the historical deviation average), then at 620, method 600 may include sensing a misfire event. In one example, the misfire event may correspond to a time when the EGR valve deviation is sensed. Additionally or alternatively, the misfire event may occur for an EGR valve position at which the EGR valve deviation is sensed. An engine misfire may include where an expected amount of combustion does not occur in at least one engine cylinder. An engine misfire may be sensed based on cylinder pressure, cylinder temperature, and / or cylinder power output being less than an expected corresponding value.

[0085] At 622 , method 600 may include determining if a misfire event is present. If a misfire event is not present, at 624 , method 600 may include not indicating EGR leak through the EGR valve.

[0086] If there is a misfire event, at 626, method 600 may include indicating that there is an EGR leak. In one example, at 628, method 600 may include activating an indicator light. Additionally or alternatively, engine operating parameters may be adjusted to account for EGR leaks and the position of the EGR valve where the leak is occurring. For example, if the EGR valve leaks when the EGR valve is commanded to a fully closed position, the adjustment may occur only during the engine operating parameters when the EGR valve is commanded to a fully closed position. Additionally or alternatively, if the EGR leak occurs during a partially open position of the EGR valve, the commanded position of the EGR valve may be adjusted to account for the EGR leak. In one example, the amount of EGR valve opening may be reduced in proportion to the amount of EGR leak. In a fully closed position including an EGR leak, engine operating conditions may be adjusted, which may include increasing the amount of fueling and / or fuel injection, increasing the amount and / or timing of sparks, etc. Additionally or alternatively, if boost is provided, the cooler may be bypassed to maintain a higher boost temperature.

[0087] In some examples, additionally or alternatively, if the engine is a multi-fuel engine and the EGR valve is leaking, an alternative fuel may be supplied. For example, if the multi-fuel engine is a diesel and hydrogen engine, hydrogen and diesel may be supplied to the engine during conditions where an EGR leak occurs to mitigate the possibility of misfire.

[0088] Now go to Figure 7 , Figure 7 A method 700 for determining a historical EGR valve average offset is shown. The method 700 begins at 702 and includes determining current operating conditions. The current operating conditions may be operating conditions for a current drive cycle. The current operating conditions may include mass air flow, manifold pressure, engine load, engine speed, EGR flow rate, and air-fuel ratio.

[0089] At 704 , method 700 may include monitoring valve excursion during a plurality of conditions during a drive cycle. For example, valve excursion during different engine loads, EGR valve positions, vehicle speeds, etc. may be monitored.

[0090] At 706 , method 700 may include applying a low pass first order filter to the sensed valve excursion.

[0091] At 708 , method 700 may include storing the filtered valve excursion as a learned excursion history in the KAM.

[0092] At 710, method 700 may include calculating an average offset history for a given condition. For example, a particular engine speed and requested EGR valve position may include an average offset history that is different from an average offset history for a different engine speed and requested EGR valve position. Different engine conditions and corresponding EGR valve positions may each include an average offset history.

[0093] At 712, method 700 may include determining, based on a future offset value (such as in Figure 6 The average offset history may be updated with the offset values ​​collected during method 600 of . In one example, only offset values ​​that are less than or equal to the average offset history may be used for updating. Offset values ​​that are greater than the average offset history and are accompanied by misfires may not be used because these offset values ​​correspond to failed diagnostic tests. In one example, if an offset value is greater than the average offset history and there is no misfire, the offset value may be used to update the average offset history. Additionally or alternatively, offset values ​​that are greater than the average offset history but there is no misfire may be flagged and / or marked. If a future offset value is lower than the average offset history, the flagged offset value may be ignored.

[0094] Now go to Figure 8 , Figure 8 A graph 800 is shown graphically illustrating various conditions for determining if an EGR leak is present. Curve 810 shows the current average valve excursion, and the dashed line shows the historical average valve excursion. Curve 820 shows if a misfire is occurring. Curve 830 shows if a flag is set. Time increases from the left side of the graph to the right side.

[0095] Prior to t1, multiple average valve offsets are acquired and compared to the historical average offsets. More specifically, two average valve offsets are acquired across two separate driving cycles. The peaks of curve 810 represent average valve offset values, and the valleys represent conditions where no driving cycle is occurring and no valve offset is sensed.

[0096] At t1, the average valve offset is acquired. Between t1 and t2, the average valve offset is greater than the historical average offset. However, since no misfire is detected, the flag is not set and the diagnostic passes. Between t2 and t3, more average valve offsets are acquired and the historical average offset is updated. As shown, the historical average offset can be consistent with the acquired average valve offset.

[0097] At t3, misfire and average valve excursion are determined. Between t3 and t4, the flag is not activated because the average valve excursion is less than the historical average excursion. At t4, the drive cycle ends.

[0098] Between t4 and t5, more driving cycles occur. Therefore, the historical average offset is updated based on the acquired average valve offset.

[0099] At t5, the drive cycle begins. Between t5 and t6, the average valve excursion is greater than the historical average excursion, and misfire is detected. At t6, the flag is activated and the drive cycle ends. After t6, the flag remains active.

[0100] The present disclosure provides support for a method for operating an exhaust gas recirculation (EGR) system, the method including applying a cooler pressure model to calculate a cooler pressure drop based on engine operating parameters and EGR flow, and diagnosing an EGR pressure (EGRP) sensor based on a comparison of an EGRP sensor reading with a manifold air pressure (MAP) sensor reading and the cooler pressure drop. A first example of the method also includes wherein the EGRP sensor is arranged between the EGR cooler and the EGR valve. A second example of the method (optionally including the first example) also includes wherein the EGR cooler is arranged between the intake port and the EGRP sensor. A third example of the method (optionally including one or more of the previous examples) also includes wherein the diagnosis includes wherein the EGR valve is closed. A fourth example of the method (optionally including one or more of the previous examples) also includes diagnosing the EGRP sensor when the EGR valve is open based on a ratio of an EGRP sensor reading to an exhaust gas sensor reading. A fifth example of the method (optionally including one or more of the previous examples) also includes wherein the exhaust gas sensor is arranged upstream of the EGR valve relative to the direction of the EGR flow and the EGRP sensor is arranged downstream of the EGR valve. A sixth example of the method (optionally including one or more of the previous examples) also includes determining that the EGRP sensor is degraded in response to the EGRP sensor reading being different than a sum of the MAP sensor reading and the cooler pressure drop.

[0101] The present disclosure provides additional support for a system including: an exhaust gas recirculation (EGR) system including an EGR valve upstream of an EGR cooler relative to a direction of EGR flow through the EGR system to an intake system, an exhaust gas sensor upstream of the EGR valve, and an EGR pressure (EGRP) sensor between the EGR valve and the EGR cooler; and a controller including computer readable instructions stored on a memory of the controller, the computer readable instructions, when executed, enabling the controller to diagnose a condition of the EGRP sensor via a first routine based on a comparison of a sum of a cooler pressure drop and a manifold air pressure (MAP) sensor reading to an EGRP sensor reading, diagnose a condition of the EGRP sensor via a second routine based on a comparison of a MAP sensor reading to an EGRP sensor reading when the EGR valve is closed, diagnose a condition of the EGRP sensor via a third routine based on a comparison of a MAP sensor reading to an EGRP sensor reading when the EGR valve is open, and diagnose a condition of the EGRP sensor based on a ratio of the EGRP sensor reading to the exhaust gas sensor reading when the EGR valve is open beyond a threshold position via a fourth routine. The first example of the system also includes where the instructions further enable the controller to determine the correction value in response to a diagnosis indicating EGRP sensor degradation. The second example of the system (optionally including the first example) also includes where the instructions further enable the controller to map the cooler pressure drop across multiple operating points of the engine connected to the intake system. The third example of the system (optionally including one or more of the previous examples) also includes where the instructions further enable the controller to determine EGRP sensor degradation during the first program in response to the EGRP sensor reading being different from the sum of the MAP sensor reading and the cooler pressure drop. The fourth example of the system (optionally including one or more of the previous examples) also includes where the instructions further enable the controller to determine EGRP sensor degradation during the second program in response to the EGRP sensor reading being different from the MAP sensor reading. The fifth example of the system (optionally including one or more of the previous examples) also includes where the instructions further enable the controller to determine EGRP sensor degradation during the third program in response to the EGRP sensor reading being different from the MAP sensor reading by a calibrated value, wherein the calibrated value is based on a quadratic curve. A sixth example of the system (optionally including one or more of the previous examples) also includes wherein the instructions further enable the controller to determine during the fourth routine that the EGRP sensor is degraded in response to the ratio deviation value 1. A seventh example of the system (optionally including one or more of the previous examples) also includes wherein the instructions further enable the controller to confirm the diagnosis of the EGRP sensor by executing two or more of the first routine, the second routine, the third routine, and the fourth routine.

[0102] The present disclosure also provides support for a method for an exhaust gas recirculation (EGR) system for a vehicle, the method including mapping a cooler pressure drop under multiple operating conditions of the vehicle, and determining degradation of an EGR pressure (EGRP) sensor based on a comparison of a sum of a manifold air pressure (MAP) sensor reading and the cooler pressure drop with an EGRP sensor reading. A first example of the method also includes indicating no degradation of the EGRP sensor in response to the EGRP sensor reading being equal to the sum of the MAP sensor reading and the cooler pressure drop. A second example of the method (optionally including the first example) also includes indicating degradation of the EGRP sensor in response to the EGRP sensor reading being different from the sum of the MAP sensor reading and the cooler pressure drop. A third example of the method (optionally including one or more of the previous examples) also includes verifying degradation of the EGRP sensor by comparing the EGRP sensor reading with a MAP sensor reading only when the EGR valve is fully closed. A fourth example of the method (optionally including one or more of the previous examples) also includes verifying degradation of the EGRP sensor by comparing the ratio of the EGRP sensor reading to the exhaust pressure sensor reading with 1.

[0103] The present disclosure provides support for a method, which includes determining the presence of an exhaust gas recirculation (EGR) leak based on a comparison of a current valve average offset with a historical EGR valve average offset. The first example of the method also includes determining the presence of an EGR leak based on the presence of an engine misfire. The second example of the method (optionally including the first example) also includes wherein the EGR leak exists in response to the current valve average offset being greater than the historical EGR valve average offset. The third example of the method (optionally including one or more of the previous examples) also includes wherein the determination of the presence of an EGR leak is not performed when the controller's keep-alive memory is actively reset. The fourth example of the method (optionally including one or more of the previous examples) also includes wherein the EGR leak does not exist in response to the current valve average offset being less than or equal to the historical EGR valve average offset. The fifth example of the method (optionally including one or more of the previous examples) also includes updating the historical EGR valve average offset based on the current valve average offset. The sixth example of the method (optionally including one or more of the previous examples) also includes wherein the current valve average offset is based on the difference between the desired EGR flow rate and the actual EGR flow rate. A seventh example of the method (optionally including one or more of the previous examples) also includes where the current valve average offset is based on an EGR pressure sensor (EGRP) / exhaust gas pressure sensor (EXP) ratio.

[0104] The present disclosure provides additional support for a system including: an exhaust gas recirculation (EGR) system including an EGR valve upstream of an EGR cooler relative to a direction of EGR flow through the EGR system to an intake system, an exhaust gas sensor upstream of the EGR valve, and an EGR pressure (EGRP) sensor between the EGR valve and the EGR cooler; and a controller including computer readable instructions stored on a memory of the controller, the computer readable instructions, when executed, enabling the controller to sense a plurality of EGR valve offsets during a plurality of driving cycles, determine an average historical EGR valve offset based on previous EGR valve offsets sensed during a plurality of previous driving cycles, determine a current EGR valve average offset during a current driving cycle, compare the current EGR valve average offset to the average historical EGR valve offset, and in response to the current EGR valve average offset being greater than the average historical EGR valve offset, determine an EGR leak in conjunction with detecting an engine misfire. The first example of the system also includes wherein the average historical EGR valve offset is one of a plurality of average historical EGR valve offsets, wherein each of the plurality of average historical EGR valve offsets is based on an operating parameter of a previous driving cycle in a plurality of previous driving cycles. The second example of the system (optionally including the first example) also includes where the current EGR valve average offset is determined based on the EGR cooler pressure model. The third example of the system (optionally including one or more of the previous examples) also includes where the instruction further causes the controller to adjust the engine operating parameters in response to the presence of EGR leakage when the EGR valve is commanded to the closed position. The fourth example of the system (optionally including one or more of the previous examples) also includes where the instruction further causes the controller to adjust the EGR valve position in response to the presence of EGR leakage when the EGR valve is in a position that is at least partially open. The fifth example of the system (optionally including one or more of the previous examples) also includes where the instruction further causes the controller to determine that there is no EGR leakage in response to the current EGR valve offset being less than or equal to the average historical EGR valve offset. The sixth example of the system (optionally including one or more of the previous examples) also includes where the instruction further causes the controller to determine that there is no EGR leakage in response to the absence of engine misfire.

[0105] The present disclosure also provides support for a method for an exhaust gas recirculation (EGR) system, the method comprising: calculating a historical average offset of an EGR valve during a plurality of previous driving cycles, i.e., an offset based on the difference between a commanded position and an actual position of the EGR valve; determining a current average offset of the EGR valve during a current driving cycle; monitoring the presence of an engine misfire; and indicating the presence of an EGR leak in response to the presence of an engine misfire, in combination with the current average offset being greater than the historical average offset. A first example of the method also includes wherein the offset is further based on one or more of the following: a cooler pressure drop model, and a ratio of EGR pressure / exhaust pressure. A second example of the method (optionally including the first example) also includes wherein the EGR pressure is sensed downstream of the EGR valve relative to the direction of the exhaust flow and the exhaust pressure is sensed upstream of the EGR valve. A third example of the method (optionally including one or more of the previous examples) also includes adjusting operating conditions in response to indicating the presence of an EGR leak, wherein the adjustment includes: adjusting one or more of the commanded positions of the EGR valve, adjusting the amount of fuel delivered to the engine, adjusting the spark timing, adjusting the fuel injection timing, adjusting the charge air guide, and adjusting the mass air flow. A fourth example of the method (optionally including one or more of the previous examples) also includes where the historical average offset is updated based on the current average offset.

[0106] It should be noted that the example control and estimation procedures included herein can be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination with various sensors, actuators and other engine hardware. The specific procedures described herein may represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various actions, operations and / or functions shown may be executed in the sequence shown, executed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown may be repeatedly performed according to the specific strategy used. In addition, the actions, operations and / or functions may be graphically represented as codes in a non-transitory memory of a computer-readable storage medium to be programmed into an engine control system, wherein the actions are implemented by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0107] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many variations are possible. For example, the above techniques may be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present 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.

[0108] As used herein, unless otherwise specified, the term "about" is interpreted to mean a range of ±5%.

[0109] The appended claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, 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 amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

[0110] According to the present invention, a method includes determining that an exhaust gas recirculation (EGR) leak exists based on a comparison of a current valve average excursion to a historical EGR valve average excursion.

[0111] In one aspect of the present invention, the method includes determining that an EGR leak is present based on the presence of an engine misfire.

[0112] In one aspect of the present invention, an EGR leak is present in response to a present valve average excursion being greater than a historical EGR valve average excursion.

[0113] In one aspect of the present invention, determining that an EGR leak exists is not performed while the keep alive memory of the controller is actively being reset.

[0114] In one aspect of the present invention, in response to the present valve average excursion being less than or equal to the historical EGR valve average excursion and the absence of EGR leak.

[0115] In one aspect of the present invention, the method includes updating a historical EGR valve mean offset based on a current valve mean offset.

[0116] In one aspect of the present invention, the current average valve excursion is based on the difference between the desired EGR flow rate and the actual EGR flow rate.

[0117] In one aspect of the present invention, the current valve average excursion is based on the EGR pressure sensor (EGRP) / exhaust gas pressure sensor (EXP) ratio.

[0118] According to the present invention, a system is provided, the system having: an exhaust gas recirculation (EGR) system, the EGR system including an EGR valve upstream of an EGR cooler relative to the direction of EGR flow through the EGR system to an intake system, an exhaust gas sensor upstream of the EGR valve, and an EGR pressure (EGRP) sensor between the EGR valve and the EGR cooler; and a controller, the controller including computer-readable instructions stored on a memory of the controller, the computer-readable instructions, when executed, enabling the controller to: sense multiple EGR valve offsets during multiple driving cycles; determine an average historical EGR valve offset based on previous EGR valve offsets sensed during multiple previous driving cycles; determine a current EGR valve average offset during a current driving cycle; compare the current EGR valve average offset with the average historical EGR valve offset; and determine an EGR leak in response to the current EGR valve average offset being greater than the average historical EGR valve offset in combination with detecting an engine misfire.

[0119] According to an embodiment, the average historical EGR valve offset is one of a plurality of average historical EGR valve offsets, wherein each of the plurality of average historical EGR valve offsets is based on an operating parameter of a previous driving cycle of a plurality of previous driving cycles.

[0120] According to an embodiment, the current EGR valve average offset is determined based on an EGR cooler pressure model.

[0121] According to an embodiment, the instructions further cause the controller to adjust an engine operating parameter in response to the presence of EGR leakage when the EGR valve is commanded to a closed position.

[0122] According to an embodiment, the instructions further cause the controller to adjust the EGR valve position in response to the presence of EGR leakage when the EGR valve is in the at least partially open position.

[0123] According to an embodiment, the instructions further cause the controller to determine that there is no EGR leak in response to the present EGR valve offset being less than or equal to the average historical EGR valve offset.

[0124] According to an embodiment, the instructions further cause the controller to determine that there is no EGR leak in response to an absence of engine misfire.

[0125] According to the present invention, a method for an exhaust gas recirculation (EGR) system includes: calculating a historical average excursion of an EGR valve during a plurality of previous driving cycles, i.e., an excursion based on a difference between a commanded position and an actual position of the EGR valve; determining a current average excursion of the EGR valve during a current driving cycle; monitoring for the presence of an engine misfire; and indicating the presence of an EGR leak in response to the presence of an engine misfire in conjunction with the current average excursion being greater than the historical average excursion.

[0126] In one aspect of the present invention, the offset is further based on one or more of: a cooler pressure drop model, and a ratio of EGR pressure / exhaust pressure.

[0127] In one aspect of the present invention, EGR pressure is sensed downstream of the EGR valve and exhaust pressure is sensed upstream of the EGR valve relative to the direction of exhaust flow.

[0128] In one aspect of the present invention, the method includes: adjusting operating conditions in response to indicating the presence of an EGR leak, wherein the adjustment includes: adjusting one or more of a commanded position of an EGR valve, adjusting an amount of fuel delivered to the engine, adjusting spark timing, adjusting fuel injection timing, adjusting charge air lead, and adjusting mass air flow.

[0129] In one aspect of the invention, the historical average offset is updated based on the current average offset.

Claims

1. A method comprising: The presence of an exhaust gas recirculation (EGR) leak is determined based on a comparison of a current valve average excursion to a historical exhaust gas recirculation (EGR) valve average excursion. 2 . The method of claim 1 , further comprising determining that the EGR leak exists based on the presence of an engine misfire. 3 . The method of claim 2 , wherein the EGR leak is present in response to the current valve average excursion being greater than the historical EGR valve average excursion. 4 . The method of claim 1 , wherein determining that the EGR leak exists is not performed while a keep alive memory of a controller is actively resetting. 5 . The method of claim 1 , wherein the absence of the EGR leak is responsive to the current valve average excursion being less than or equal to the historical EGR valve average excursion. 6 . The method of claim 5 , further comprising updating the historical EGR valve average offset based on the current valve average offset.

7. The method of claim 1 wherein the current average valve excursion is based on a difference between a desired EGR flow rate and an actual EGR flow rate.

8. The method of claim 1 wherein said current valve average excursion is based on an EGR pressure sensor (EGRP) / exhaust gas pressure sensor (EXP) ratio.

9. A system comprising: an exhaust gas recirculation (EGR) system including an EGR valve upstream of an EGR cooler relative to a direction of EGR flow through the EGR system to an intake system, an exhaust gas sensor upstream of the EGR valve, and an EGR pressure (EGRP) sensor between the EGR valve and the EGR cooler; as well as A controller comprising computer readable instructions stored on a memory of the controller, the computer readable instructions, when executed, enabling the controller to: sensing a plurality of EGR valve excursions during a plurality of driving cycles; determining an average historical EGR valve offset based on previous EGR valve offsets sensed during a plurality of previous driving cycles; determining a current average EGR valve excursion during a current driving cycle; comparing the current average EGR valve offset to the average historical EGR valve offset; as well as An EGR leak is determined in response to the present average EGR valve excursion being greater than the average historical EGR valve excursion in conjunction with detecting an engine misfire.

10. The system of claim 9, wherein the average historical EGR valve offset is one of a plurality of average historical EGR valve offsets, wherein each of the plurality of average historical EGR valve offsets is based on an operating parameter of a previous drive cycle in the plurality of previous drive cycles.

11. The system of claim 9 wherein the current EGR valve average offset is determined based on an EGR cooler pressure model.

12. The system of claim 9, wherein the instructions further cause the controller to adjust an engine operating parameter in response to the presence of the EGR leak when the EGR valve is commanded to a closed position.

13. The system of claim 9 wherein the instructions further cause the controller to adjust an EGR valve position in response to the presence of the EGR leak when the EGR valve is in the at least partially open position.

14. The system of claim 9 wherein the instructions further cause the controller to determine that the EGR leak is not present in response to the current EGR valve offset being less than or equal to the average historical EGR valve offset.

15. The system of claim 9 wherein the instructions further cause the controller to determine that the EGR leak is absent in response to an absence of the engine misfire.

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