SYSTEM AND METHOD FOR OPERATING AN ENGINE

Abstract

A method of operating an engine, comprising: Receiving a differential pressure sensor output and a manifold pressure sensor output at a controller; Judging, via the control device, whether or not an exhaust gas recirculation system fault exists in response to the differential pressure sensor output and the intake manifold pressure sensor output during operation of an engine with an intake manifold pressure greater than atmospheric pressure, via the control device, the judgment being based on the differential pressure sensor output exceeding a second threshold, and further comprising: Converting the differential pressure sensor output into a differential pressure; and Adjusting an actuator coupled to the motor and the controller via the controller in response to the assessment.

Description

State of the art / brief description

[0001] An engine may include an external exhaust gas recirculation (EGR) system to reduce NOx emissions and improve engine efficiency. The external EGR system may couple an engine exhaust manifold to an engine intake manifold. The EGR system may also include temperature and pressure sensors to estimate the amount of EGR flowing to the engine cylinders. During operation, an EGR actuator, EGR sensor, EGR line, or EGR hose may become disconnected. The EGR component may become loose due to engine boost pressure, vibrations caused by irregular road surfaces, or other conditions.

[0002] EGR systems can be evaluated for malfunctions during engine idle conditions, where engine operating conditions may be consistent. Testing the EGR system during engine idle conditions can reduce the possibility of false negative or false positive EGR system malfunction reports, as engine operating conditions may be more consistent during engine idle. Nevertheless, to further improve vehicle fuel economy, engines are operated without the need to operate during idle conditions. It may therefore be desirable to provide a means of reliably testing an EGR system during conditions other than engine idle and adjusting engine operation in response to the EGR system test.

[0003] For example, document US 2015 / 0 128 916 A1 describes a method and a system for operating an engine in which exhaust gas recirculation is controlled depending on sensor-detected engine operating parameters, including a pressure signal in the intake tract. Further methods and systems for operating an engine with exhaust gas recirculation are known from documents US 6 687 601 B2 and US 6 850 833 B1.

[0004] The present invention is based on the object of creating improved methods and systems for operating an engine which avoid the disadvantages of the prior art described and, in particular, allow the EGR system to be reliably checked for faults without having to operate the engine at idle.

[0005] According to the invention, the above object is achieved by a method according to claim 1 and a vehicle system according to claim 7, wherein preferred embodiments of the invention are the subject of the dependent claims.

[0006] Accordingly, a method of operating an engine comprises: receiving a differential pressure sensor output and a manifold pressure sensor output at a controller; judging whether or not an exhaust gas recirculation system fault exists in response to the differential pressure sensor output and the manifold pressure sensor output during operation of an engine with a manifold pressure greater than atmospheric pressure, via the controller; and adjusting an engine actuator, via the controller, in response to the judgment.

[0007] By testing an EGR system when engine intake manifold pressure is greater than barometric pressure, it may be possible to expand the conditions under which an EGR system can be tested so that the engine does not have to run at idle conditions and consume fuel while idling. Furthermore, expanding the EGR system evaluation to include conditions where the engine is operating at higher engine intake manifold pressure may provide faster remedial action and notification of an EGR system malfunction. In one example, the output of a differential pressure sensor may be evaluated at engine intake manifold pressures higher than barometric pressure, allowing the evaluation of an EGR system malfunction to be determined more frequently than systems that only evaluate an EGR system malfunction at engine idle conditions.Additionally, the output of the differential pressure sensor and the output of the engine intake manifold pressure sensor can be useful for testing an EGR system at lower engine load conditions without having to idle the engine.

[0008] The present description can offer several advantages. In particular, the approach can provide faster notifications of an EGR system malfunction. Additionally, the approach can evaluate an EGR system over a wider range of engine operating conditions to enable faster remedial actions. Furthermore, the approach can reduce engine emissions by reliably reporting an EGR system malfunction.

[0009] The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description taken alone or in conjunction with the accompanying drawings.

[0010] It should be understood that the Summary above is provided to introduce, in simplified form, a selection of concepts further described in the Detailed Description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Short description of the characters Fig. 1 shows a schematic diagram of an engine; Fig. 2 shows a schematic illustration of an exemplary vehicle powertrain including an engine; The Fig. 3 and Fig. 4 show exemplary graphical representations of differential pressure sensor outputs; and Fig. 5 shows an exemplary method for operating an engine. Detailed description

[0011] This description relates to the operation of an engine incorporating an external exhaust gas recirculation (EGR) system. The engine may be Fig. 1. The motor of the Fig. 1 can be integrated into a vehicle drive train as in Fig. 2, and the motor can be the sole or only adjustable torque source in the drivetrain. Fig. 3 and Fig. 4 show differential pressure sensor output profiles during EGR system failure conditions. The engine may be cooled according to the procedure described in Fig. 5 is shown.

[0012] With reference to Fig. 1, an internal combustion engine 10 having a plurality of cylinders, of which one cylinder is Fig. 1, is controlled by an electronic engine control device 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32, with a piston 36 positioned therein and connected to a crankshaft 40. The combustion chamber 30 is shown in communication with the intake manifold 44 and an exhaust manifold 48 via a respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be actuated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 may be determined by an intake cam sensor 55. The position of the exhaust cam 53 may be determined by an exhaust cam sensor 57.

[0013] A fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, known to those skilled in the art as direct fuel injection. The fuel injector 66 delivers liquid fuel proportional to the pulse width from a controller 12. The fuel may be delivered to the fuel injector 66 via a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel rail (not shown). In one example, a two-stage high-pressure fuel system may be used to generate higher fuel pressures.

[0014] Additionally, intake manifold 44 is shown in communication with a turbocharger compressor 162 and an engine air intake 42. In other examples, compressor 162 may be a supercharging compressor. A shaft 161 mechanically couples a turbocharger turbine 164 to turbocharger compressor 162. An optional electronic throttle 62 (e.g., central or engine intake manifold throttle) adjusts a position of a throttle plate 64 to control airflow from compressor 162 to intake manifold 44. Pressure in a boost chamber 45 may be called throttle inlet pressure because the inlet of throttle 62 is within boost chamber 45. The throttle outlet is located in intake manifold 44. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44 such that throttle 62 is a port throttle.A compressor recirculation valve 47 can be selectively set to a variety of positions between fully open and fully closed. A wastegate 163 can be adjusted via the controller 12 to allow exhaust gases to selectively bypass the turbine 164 to control the speed of the compressor 162.

[0015] The air cleaner 43 cleans air entering the engine air intake 42 through the intake 3, which is subject to ambient temperature and pressure. Converted combustion byproducts are expelled at the outlet 5, which is subject to ambient temperature and pressure. In this way, the piston 36 and combustion chamber 30 can operate as a pump as the engine 10 rotates to draw air from the intake 3 and expel exhaust combustion byproducts to the outlet 5. The inlet 3 is located upstream of the outlet 5 according to a flow direction through the engine 10, the exhaust manifold 48, and the engine air intake 42. Upstream includes nothing external to the engine past the intake 3, and downstream includes nothing external to the engine past the outlet 5.

[0016] A distributorless ignition system 88 provides an ignition spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. A wideband Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to the exhaust manifold 48 upstream of the catalytic converter 70. Alternatively, a binary oxygen sensor may replace the UEGO sensor 126.

[0017] The catalyst 70 may, in one example, include multiple catalyst bricks. In another example, a plurality of emission control devices, each having a plurality of bricks, may be used. The catalyst 70 may, in one example, be a three-way catalyst.

[0018] External EGR may be supplied to the engine via lines 170 and 176. Exhaust gases may flow in the direction of arrow 175 when an EGR valve 174 is opened. The EGR valve 174 may be closed when the pressure in the intake manifold 44 is above atmospheric pressure. The EGR cooler 171 cools EGR gases, and the pressure sensor 172 and the temperature sensor 173 provide exhaust gas data to the controller 12. The EGR valve 173 may be opened in variable amounts from fully open to fully closed. EGR flows through orifice 180 so that the EGR flow rate can be determined from the differential pressure sensor 178. A pipe 177 provides upstream EGR pressure to the differential pressure sensor 178. A pipe 179 provides downstream EGR pressure to the differential pressure sensor 178.

[0019] The control device 12 is in Fig. 1 as a conventional microcomputer including: a microprocessor unit 102, input / output ports 104, read-only memory 106 (e.g., non-volatile memory), random access memory 108, retaining memory 110, and a conventional data bus. The controller 12 is shown receiving, in addition to the signals discussed above, various signals from sensors coupled to the engine 10, including: engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 for sensing force applied by the driver 132; and a throttle position sensor 134.a position sensor 154 coupled to a brake pedal 150 for sensing force applied by the driver 132; a measurement of intake manifold pressure (engine manifold sensor - MAP) from a pressure sensor 123 coupled to the intake manifold 44; a measurement of engine boost pressure or throttle inlet pressure from pressure sensor 122; engine position from a Hall sensor 118 sensing the position of the crankshaft 40; a measurement of absolute exhaust manifold pressure from pressure sensor 190;a measurement of the air mass entering the engine from sensor 120; and a measurement of throttle position from sensor 68. Barometric pressure may also be sensed via sensor 191 for processing by controller 12. In a preferred aspect of the present description, an engine position sensor 118 generates a predetermined number of evenly spaced pulses at each revolution of the crankshaft, from which engine speed (RPM) can be determined.

[0020] During operation, each cylinder within the engine 10 typically experiences a four-stroke cycle: the cycle includes the intake stroke, the compression stroke, the power stroke, and the exhaust stroke. During the intake stroke, the exhaust valve 54 generally closes and the intake valve 52 opens. Air is introduced into the combustion chamber 30 via the intake manifold 44, and the piston 36 moves to the bottom of the cylinder to increase the volume within the combustion chamber 30. The position where the piston 36 is near the bottom of the cylinder and at the end of its stroke (for example, when the combustion chamber 30 is at its largest volume) is typically referred to by those skilled in the art as bottom dead center (BDC).

[0021] During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air in combustion chamber 30. The position where piston 36 is at the end of a stroke and closest to the cylinder head (for example, when combustion chamber 30 is at its smallest volume) is typically referred to by those skilled in the art as top dead center (TDC). In an event referred to below as injection, fuel is introduced into the combustion chamber. In an event referred to below as ignition, the injected fuel is ignited by a known ignition means, such as spark plug 92, resulting in combustion.

[0022] During the power stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston motion into rotating shaft torque. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48, and the piston returns to TDC. It should be noted that the above is shown merely as an example, and the timing of intake and exhaust valve opening and / or closing may vary to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0023] With reference to Fig. 2 is Fig. 2 is a block diagram of a vehicle 225 including a drivetrain or transmission 200. The drivetrain of the Fig. 2 contains the motor 10, which is Fig. 1. The engine 10 includes one or more torque actuators 204 (e.g., a throttle, camshaft, fuel injector, etc.). The powertrain 200 may be driven by the engine 10. The engine crankshaft 40 is shown coupled to an optional dual-mass flywheel 280, and the dual-mass flywheel 280 is shown mechanically coupled to the optional powertrain disconnect clutch 201, which is shown mechanically coupled to the impeller 285 of the torque converter 206. The torque converter impeller 285 is mechanically coupled to the transmission pump 289. The mechanically driven transmission pump 289 supplies pressurized transmission fluid to the forward transmission clutch 210 and the gear clutches (e.g., gear clutches 1 through 10). The torque converter 206 also includes a turbine 286 coupled to a transmission input shaft 270.The transmission input shaft 270 mechanically couples the torque converter 206 to the automatic transmission 208, and its speed is monitored via the speed sensor 217. The torque converter 206 also includes a torque converter bypass clutch (TCC) 212. Torque is transferred directly from the impeller 285 to the turbine 286 when the TCC is locked. The TCC is electrically operated by the controller 12. Alternatively, the TCC may be hydraulically locked in a closed state. In one example, the torque converter may be called a component of the transmission. Further, the TCC may be partially closed, providing adjustable torque capacity for the TCC. The TCC provides a frictional torque path through the torque converter 206, while torque may also be transferred by fluid between the impeller 206 and the turbine 286.Torque transmitted by fluid follows a torque fluid path from the impeller 285 to the turbine wheel 286.

[0024] When the torque converter clutch 212 is fully engaged, the torque converter 206 transfers engine torque to the automatic transmission 208 via fluid transfer between the torque converter turbine 286 and the torque converter impeller 285, enabling torque multiplication. In contrast, when the torque converter clutch 212 is fully engaged, the engine torque output is transferred directly via the torque converter clutch to an input shaft 270 of the transmission 208. Alternatively, the torque converter clutch 212 may be partially engaged, allowing the amount of torque passed directly to the transmission to be adjusted.The controller 12 may be configured to adjust the amount of torque transmitted by the torque converter 212 by adjusting pressure to actuate the torque converter lock-up clutch in response to various engine operating conditions or based on a driver request for engine operation.

[0025] The automatic transmission 208 includes gear clutches 211 and a forward clutch 210 for engaging or disengaging gears 209 (e.g., reverse and gears 1 through 10). The gear clutches 211 (e.g., 1 through 10) and the forward clutch 210 can be selectively engaged to propel a vehicle. The transmission 208 is configured such that a gear of the gears 209 can be engaged by actuating two or more of the clutches 211. In other words, a gear can be positively engaged when two or more clutches 211 are closed. Further, the transmission 208 can be placed in a neutral state when the input shaft 270 is not engaged or coupled to the output shaft 260 when one or more of the clutches 211 are open, but while one or more of the clutches 211 are closed.A torque output from the automatic transmission 208 may be transmitted to the wheels 216 to drive the vehicle via an output shaft 260. A speed of the output shaft 260 is monitored by the speed sensor 219. Specifically, the automatic transmission 208 may transmit input drive torque to the input shaft 270 in response to a vehicle driving condition before transmitting output drive torque to the wheels 216.

[0026] Furthermore, a frictional force may be applied to the wheels 216 by engaging wheel brakes 218. In one example, the wheel brakes 218 may be applied in response to the driver placing their foot on a brake pedal, as shown in Fig. 1. In other examples, the controller 12 or a controller coupled to the controller 12 may apply wheel brakes. In the same way, a frictional force on the wheels 216 may be reduced by deactivating the wheel brakes 218 in response to the driver removing their foot from the brake pedal. Further, vehicle brakes may apply a frictional force to the wheels 216 via the controller 12 as part of an automated engine stop procedure.

[0027] Torque flows from the engine 10 to the transmission 208 before being applied to the wheels 216. The engine 10 is therefore upstream of the torque converter 206, the transmission 208, and the wheels 216 in a direction of torque flow.

[0028] The controller 12 may be configured to receive inputs from the engine 10, as described in more detail in Fig. 1, and consequently control a torque output of the engine and / or the operation of the torque converter, transmission, clutches, and / or brakes. Further, the controller 12 may receive driver input from a human-machine interface 299. In some examples, the human-machine interface 299 may provide powertrain information and messages to a driver. In the case of a diesel engine, the controller 12 may control the engine torque output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In any case, engine control may be performed on a cylinder-by-cylinder basis to control the engine torque output.

[0029] The systems of Fig. 1 and Fig. 2 therefore provide a vehicle system comprising: an engine including an intake manifold and an exhaust manifold; an exhaust gas recirculation system including a conduit coupling the intake manifold to the exhaust manifold, a differential pressure sensor located along the conduit, and a manifold pressure sensor; a barometric pressure sensor; and a controller including executable instructions stored in non-volatile memory to adjust a state of an actuator in response to an exhaust gas recirculation system fault indication based on an absolute value of an output of the differential pressure sensor being greater than a sixth threshold and an absolute pressure of an output of the engine manifold pressure sensor less an output of the barometric pressure sensor being greater than a fifth threshold.

[0030] In some examples, the vehicle system includes where the actuator is a fuel injector. The vehicle system also includes where the actuator is a throttle valve. The vehicle system also includes where the actuator is an ignition system. The vehicle system further includes additional instructions to adjust the actuator in response to an exhaust gas recirculation system fault notification based on an output of the differential pressure sensor being greater than a fourth threshold and an absolute value of an output of the engine manifold pressure sensor less an output of the barometric pressure sensor being greater than a third threshold. The vehicle system includes where the executable instructions are executed when the engine is not idling.

[0031] With reference to Fig. Figure 3 shows a graphical representation of EGR system differential pressure versus engine manifold pressure less barometric pressure. The vertical axis represents EGR system differential pressure. The horizontal axis represents engine manifold pressure less barometric pressure. The engine is operating with manifold pressure greater than barometric pressure when manifold pressure less barometric pressure is greater than zero. The engine is operating with manifold pressure less than barometric pressure when manifold pressure less barometric pressure is less than zero.

[0032] Quadrant I is the upper right quadrant of the graph and extends rightward from zero engine manifold pressure and above zero differential pressure. Quadrant I contains subquadrant Ia and is bounded on its left side by vertical line 310 and on its lower side by horizontal line 311. Subquadrant Ia represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the engine manifold pressure less barometric pressure is greater than a first predetermined threshold and when the differential pressure is greater than a second predetermined threshold (e.g., the region within subquadrant Ia).

[0033] Quadrant II is the upper left quadrant of the graph and extends to the left from zero engine manifold pressure and above zero differential pressure. Quadrant II contains subquadrant IIa and is bounded on its right side by vertical line 301 and on its lower side by horizontal line 304. Subquadrant IIa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the absolute value of the engine manifold pressure less the barometric pressure is greater than a third predetermined threshold and when the differential pressure is greater than a fourth predetermined threshold (for example, the region within subquadrant IIa).

[0034] Quadrant III is the lower left quadrant of the graph and extends to the left from zero engine manifold pressure and below zero differential pressure. Quadrant III contains subquadrant IIIa and is bounded on its right side by vertical line 302 and on its upper side by horizontal line 303. Subquadrant IIIa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the absolute value of the engine manifold pressure less the barometric pressure is greater than a fifth predetermined threshold and when the absolute value of the differential pressure is greater than a sixth predetermined threshold (for example, the region within subquadrant IIIa).

[0035] Quadrant IV is the lower right quadrant of the graph and extends rightward from zero engine manifold pressure and below zero differential pressure. Quadrant IV contains subquadrant IVa and is bounded on its left side by vertical line 312 and on its upper side by horizontal line 313. Subquadrant IVa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the engine manifold pressure less barometric pressure is greater than a seventh predetermined threshold and when an absolute value of the differential pressure is greater than an eighth predetermined threshold (for example, the region within subquadrant IVa).

[0036] The curve 350, shown as points indicated by #, represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when a hose is disconnected or there is a leak downstream of the differential pressure sensor. For example, if hose 179 of the Fig. 1 is unplugged, the differential pressure sensor output is similar to curve 350.

[0037] The curve 352, shown as points indicated by +, represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when a hose is disconnected or there is a leak upstream of the differential pressure sensor. For example, if hose 177 of the Fig. 1 is unplugged, the differential pressure sensor output is similar to curve 352.

[0038] The curve 351, shown as points indicated by *, represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when no hose is disconnected or there are no leaks in the EGR system.

[0039] It can be observed that curve 351 does not enter subquadrants Ia, IIa, IIIa, and IVa. However, if a hose is disconnected or there is a leak in the EGR system, measurements from the differential pressure sensor and measurements from the engine intake manifold pressure sensor, less measurements from the barometric pressure sensor, will enter regions Ia, IIa, IIIa, and IVa during certain operating conditions, as indicated above. Therefore, if the output from the differential pressure sensor, barometric pressure sensor, and engine intake manifold pressure sensor indicates operating conditions in subquadrants Ia, IIa, IIIa, or IVa, it can be judged that an EGR system malfunction exists because curve 351 does not enter these operating regions. In this way, an EGR system malfunction can be evaluated under conditions other than engine idle conditions.

[0040] With reference to Fig. Figure 4 shows a graphical representation of EGR system differential pressure versus engine manifold pressure minus absolute exhaust gas pressure. The vertical axis represents EGR system differential pressure. The horizontal axis represents engine manifold pressure minus absolute exhaust gas pressure. The engine is operating with manifold pressure greater than atmospheric pressure when manifold pressure minus absolute exhaust gas pressure is greater than zero. The engine is operating with manifold pressure less than atmospheric pressure when manifold pressure minus absolute exhaust gas pressure is less than zero.

[0041] Quadrant I is the upper right quadrant of the graph and extends rightward from zero engine manifold pressure and above zero differential pressure. Quadrant I contains subquadrant Ia and is bounded on its left side by vertical line 410 and on its lower side by horizontal line 411. Subquadrant Ia represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the engine manifold pressure less the absolute exhaust pressure is greater than a first predetermined threshold and when the differential pressure is greater than a second predetermined threshold (e.g., the region within subquadrant Ia).

[0042] Quadrant II is the upper left quadrant of the graph and extends to the left from zero engine intake manifold pressure and above zero differential pressure. Quadrant II contains subquadrant IIa and is bounded on its right side by vertical line 401 and on its lower side by horizontal line 404. Subquadrant IIa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the absolute value of the engine intake manifold pressure less the absolute exhaust pressure is greater than a third predetermined threshold, and when the differential pressure is greater than a fourth predetermined threshold (for example, the region within subquadrant IIa).

[0043] Quadrant III is the lower left quadrant of the graph and extends to the left from zero engine intake manifold pressure and below zero differential pressure. Quadrant III contains subquadrant IIIa and is bounded on its right side by vertical line 402 and on its upper side by horizontal line 403. Subquadrant IIIa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the absolute value of the engine intake manifold pressure less the absolute exhaust pressure is greater than a fifth predetermined threshold, and when the absolute value of the differential pressure is greater than a sixth predetermined threshold (for example, the region within subquadrant IIIa).

[0044] Quadrant IV is the lower right quadrant of the graph and extends rightward from zero engine manifold pressure and below zero differential pressure. Quadrant IV contains subquadrant IVa and is bounded on its left side by vertical line 412 and on its upper side by horizontal line 413. Subquadrant IVa represents a region where an EGR system malfunction exists. An EGR system malfunction exists when the engine manifold pressure less the absolute exhaust pressure is greater than a seventh predetermined threshold and when the absolute value of the differential pressure is greater than an eighth predetermined threshold (for example, the region within subquadrant IVa).

[0045] Curve 450 represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when a hose is disconnected or there is a leak downstream of the differential pressure sensor. For example, if hose 179 of the Fig. 1 is unplugged, the differential pressure sensor output is similar to curve 450.

[0046] Curve 452 represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when a hose is disconnected or there is a leak upstream of the differential pressure sensor. For example, if hose 177 of the Fig. 1 is unplugged, the differential pressure sensor output is similar to curve 452.

[0047] Curve 451 represents differential pressure as measured by a differential pressure sensor (for example, 178 of the Fig. 1) is measured when no hose is disconnected or there are no leaks in the EGR system.

[0048] It can be observed that curve 451 does not enter subquadrants Ia, IIa, IIIa, and IVa. However, if a hose is disconnected or there is a leak in the EGR system, measurements from the differential pressure sensor and measurements from the engine intake manifold pressure sensor, less measurements from the exhaust pressure sensor, will enter regions Ia, IIa, IIIa, and IVa during certain operating conditions, as indicated above. If the output from the differential pressure sensor, exhaust pressure sensor, and engine intake manifold pressure sensor indicates operating conditions in subquadrants Ia, IIa, IIIa, or IVa, it can be judged that an EGR system malfunction exists because curve 451 does not enter these operating regions. In this way, an EGR system malfunction can be evaluated under conditions other than engine idle conditions.

[0049] With reference to Fig. 5 shows a method for operating a motor. The method of Fig. 5 can be applied to the drive train, which is located in the Fig. 1 and Fig. 2. Furthermore, at least sections of the method from Fig. 5 as executable instructions in the system Fig. 1 and Fig. 2. In addition, at least sections of the procedure of the Fig. 5 actions taken within the physical world to transform states of engine actuators and other engine and transmission components.

[0050] At 502, method 500 judges whether the engine is running (e.g., combusting air and fuel). The engine may be judged to be running if the engine speed is greater than a threshold and spark and fuel are being supplied to the engine. If method 500 judges that the engine is running, the answer is yes, and method 500 proceeds to 504. Otherwise, the answer is no, and method 500 ends.

[0051] At 504, method 500 samples the output of a differential or delta pressure sensor to determine a pressure differential across an orifice in the EGR system. In one example, the differential pressure voltage output is converted to differential pressure via a transfer function using differential pressure sensor voltage as input to the transfer function. Method 500 proceeds to 506 after sampling the differential pressure sensor output and determining differential pressure at the differential pressure sensor.

[0052] At 506, method 500 samples the output of an engine manifold absolute pressure (MAP) sensor. In one example, the MAP sensor voltage output is converted to pressure via a transfer function using MAP sensor voltage as input to the transfer function. Method 500 proceeds to 508 after the MAP sensor output is sampled and the manifold absolute pressure is determined.

[0053] At 508, method 500 samples an output of a barometric pressure sensor or an exhaust manifold sensor to determine a barometric pressure or exhaust manifold absolute pressure. In one example, the barometric pressure sensor or exhaust pressure sensor pressure voltage output is converted to barometric pressure or exhaust pressure via a transfer function using the exhaust pressure sensor voltage or barometric pressure sensor voltage as input to the transfer function. Method 500 proceeds to 510 after the barometric pressure sensor output or exhaust pressure sensor output is sampled and exhaust pressure or barometric pressure is determined.

[0054] At 510, method 500 assesses the sensor output from the differential pressure sensor, barometric pressure sensor, engine exhaust manifold pressure sensor, and the engine intake manifold pressure sensors indicate that the differential pressure sensor is experiencing conditions defined in sub-quadrants Ia, IIa, IIIa, or IVa of the EGR representations shown in the Fig. 3 and Fig. 4. For example, it may be judged that an EGR system malfunction exists when the engine intake manifold pressure less the atmospheric pressure is greater than a predetermined threshold, and when the differential pressure is greater than a second predetermined threshold, as shown in Fig. 3. Further, it may be judged that an EGR system malfunction exists when the absolute value of the engine intake manifold pressure minus the atmospheric pressure is greater than a third predetermined threshold, and when the differential pressure is greater than a fourth predetermined threshold. It may also be judged that an EGR system malfunction exists when the absolute value of the engine intake manifold pressure minus the atmospheric pressure is greater than a fifth predetermined threshold, and when the absolute value of the differential pressure is greater than a sixth predetermined threshold. In addition, it may be judged that an EGR system malfunction exists when the engine intake manifold pressure minus the atmospheric pressure is greater than a seventh predetermined threshold, and when the absolute value of the differential pressure is greater than an eighth predetermined threshold.

[0055] Therefore, if the differential pressure sensor output and the intake manifold pressure sensor output indicate that the system is operating in subquadrants Ia, IIa, IIIa, or IVa, an EGR system fault may be determined. If method 500 determines that an EGR system fault exists, the answer is yes, and method 500 proceeds to 512. Otherwise, the answer is no, and method 500 proceeds to 520.

[0056] At 512, method 500 reports an EGR system fault, and the condition is latched to memory. Method 500 may report an EGR system fault via a human-machine interface, a dashboard light, or other known type of indicator. Further, the EGR system fault report may be stored as a value in a bit or word of memory. For example, a bit in memory may change from a value of zero to a value of one to report an EGR system fault. The value may be stored in memory or may remain latched in memory until a service technician resets the bit to a value of zero via a human-machine interface. Method 500 proceeds to 514.

[0057] At 514, method 500 controls the EGR valve closed for all driving conditions. Closing the EGR valve may stop exhaust flow to the EGR port, preventing EGR from flowing out of the engine without being treated via an emissions control device. Furthermore, closing the EGR valve may prevent airflow into the exhaust system, which may improve engine emissions during an EGR system malfunction. Method 500 proceeds to 516.

[0058] At 516, method 500 may adjust the engine throttle, ignition timing, and fuel injection quantity. If unmetered air enters the engine from the EGR system during low driver demand torque, the exhaust oxygen sensor may signal lean combustion. The throttle may be adjusted in a closing direction to compensate for the additional air provided by the damaged EGR system. Ignition energy may also be increased by increasing ignition coil dwell time during periods in which lean combustion may be observed. Further, the injection fuel pulse width may be increased to provide a stoichiometric air-fuel ratio to the engine if air flows into the intake manifold via the EGR system.If the amount of fuel is increased to provide a stoichiometric air-fuel mixture, the ignition timing can be retarded so that the desired driver demand torque is provided by the engine.

[0059] If the engine is operating at a higher demand torque, the exhaust oxygen sensor may indicate rich combustion due to pressurized air leaking from the EGR system from the pressurized engine intake manifold. The amount of boost may be adjusted by adjusting a wastegate position to provide a desired boost pressure. Method 500 ends after the EGR disturbance is reported and mitigated.

[0060] At 520, method 500 judges whether an EGR fault message is cached in memory. In one example, method 500 reads a value of a bit or a word in memory. If the bit or word indicates that an EGR fault is present, the answer is yes, and method 500 proceeds to 514. Otherwise, the answer is no, and method 500 proceeds to 522.

[0061] At 522, method 500 adjusts a position of the EGR valve based on a desired EGR flow rate and output of the differential or delta pressure sensor. In one example, a flow rate estimated from the differential pressure sensor output is subtracted from a desired EGR flow rate, and the EGR valve position is adjusted in response to the result. The desired EGR flow rate may be determined empirically and stored in a table or function indexed by engine torque and engine speed. Method 500 ends after the EGR valve position is adjusted.

[0062] The procedure of Fig. 5 therefore provides a method of operating an engine, comprising: receiving a differential pressure sensor output and a manifold pressure sensor output at a controller; judging, via the controller, whether or not an exhaust gas recirculation system fault exists in response to the differential pressure sensor output and the manifold pressure sensor output during operation of an engine with a manifold pressure greater than atmospheric pressure; and adjusting an actuator, via the controller, in response to the judgment. The method includes the actuator being a wastegate.

[0063] In some examples, the method further comprises converting the differential pressure sensor output to a differential pressure, wherein the judgment is based on the differential pressure exceeding a second threshold. The method further comprises converting the intake manifold sensor pressure output to a manifold pressure, wherein the judgment is also based on the manifold pressure less a barometric pressure exceeding a first threshold. The method further comprises converting the differential pressure sensor output to a differential pressure, wherein the judgment is based on an absolute value of the differential pressure exceeding an eighth threshold. The method further comprises converting the manifold sensor pressure output to a manifold pressure, wherein the judgment is also based on the manifold pressure less a barometric pressure exceeding a seventh threshold.The method further includes closing an exhaust gas recirculation valve during operation of the engine with an intake manifold pressure greater than atmospheric pressure.

[0064] The procedure of Fig. 5 also provides a method of operating an engine, comprising: receiving a differential pressure measurement and a second measurement at a controller; assessing the presence of an EGR system fault upstream of a differential pressure sensor in response to an absolute value of the differential pressure measurement being greater than an eighth threshold and an engine manifold pressure less the second measurement being greater than a seventh threshold; and adjusting an actuator via the controller in response to the assessment. The method further comprises assessing the presence of an EGR system fault downstream of a differential pressure sensor in response to the differential pressure measurement being greater than a second threshold and an engine manifold pressure less the second measurement being greater than a first threshold. The method includes where the second measurement is a measurement of barometric pressure.The method includes the second measurement being a measurement of an exhaust manifold pressure.

[0065] In some examples, the method further comprises assessing the presence of an EGR system fault downstream of a differential pressure sensor in response to an absolute value of the differential pressure measurement being greater than a sixth threshold and an absolute value of the engine manifold pressure less the second measurement being greater than a fifth threshold. The method further comprises assessing the presence of an EGR system fault upstream of a differential pressure sensor in response to the differential pressure measurement being greater than a fourth threshold and an engine manifold pressure less the second measurement being greater than a third threshold. The method includes the engine operating at a positive manifold pressure while the controller receives the differential pressure measurement and the second pressure measurement.

[0066] It should be noted that the control and estimation routines contained herein can be used with various engine and / or vehicle system designs. The control methods and routines disclosed herein can be stored as executable instructions in non-volatile memory and implemented by the control system, including the controller, in combination with the various sensors, actuators, and other engine hardware to manipulate operating states of the various disclosed devices. As one of ordinary skill in the art will appreciate, the Fig.7 may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Therefore, various illustrated steps or functions may be performed in the order shown, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the objects, features, and advantages, but is provided for ease of illustration and description. Although not explicitly shown, it will be apparent to one of ordinary skill in the art that one or more of the illustrated steps or functions may be performed repeatedly depending on the particular strategy employed.Furthermore, the methods described herein may be a combination of actions taken by a controller in the physical world and instructions within the controller.

[0067] This description ends. Upon reading this specification, one skilled in the art would envision numerous modifications and alterations without departing from the spirit and scope of the specification. For example, single-cylinder, I2, I3, I4, I5, V6, V8, V10, V12, and V16 engines operating on natural gas, gasoline, or alternative fuel configurations could advantageously utilize the present specification.

Claims

[1] A method of operating an engine, comprising: Receiving a differential pressure sensor output and a manifold pressure sensor output at a controller; Judging, via the control device, whether or not an exhaust gas recirculation system fault exists in response to the differential pressure sensor output and the intake manifold pressure sensor output during operation of an engine with an intake manifold pressure greater than atmospheric pressure, via the control device, the judgment being based on the differential pressure sensor output exceeding a second threshold, and further comprising: Converting the differential pressure sensor output into a differential pressure; and Adjusting an actuator coupled to the motor and the controller via the controller in response to the assessment. [2] The method of claim 1, wherein the actuator is a wastegate of a turbocharger coupled to the engine. [3] The method of claim 1, further comprising converting the intake manifold pressure sensor output to an intake manifold pressure, wherein the assessment is also based on the intake manifold pressure less an air pressure exceeding a first threshold. [4] The method of claim 1, wherein the assessment is based on an absolute value of the differential pressure exceeding an eighth threshold value. [5] The method of claim 4, further comprising converting the intake manifold pressure sensor output to an intake manifold pressure, wherein the assessment is also based on the intake manifold pressure less an air pressure exceeding a seventh threshold. [6] The method of claim 1, further comprising closing an exhaust gas recirculation valve while operating the engine with the intake manifold pressure greater than the atmospheric pressure. [7] Vehicle system comprising: an engine having an intake manifold and an exhaust manifold; an exhaust gas recirculation system including a conduit coupling the intake manifold to the exhaust manifold, a differential pressure sensor located along the conduit, and an intake manifold pressure sensor; an air pressure sensor; and a controller including executable instructions stored in non-volatile memory for adjusting a state of an actuator during operation of the engine in response to an exhaust gas recirculation system fault indication based on an absolute value of an output of the differential pressure sensor being greater than a sixth threshold as determined via the controller, and an absolute value of an output of the engine intake manifold pressure sensor less an output of the barometric pressure sensor being greater than a fifth threshold as determined via the controller. [8] The vehicle system of claim 7, wherein the actuator is a fuel injector. [9] The vehicle system of claim 7, wherein the actuator is a throttle valve. [10] The vehicle system of claim 7, wherein the actuator is an ignition system. [11] The vehicle system of claim 7, further comprising additional instructions for adjusting the actuator during engine operation in response to the exhaust gas recirculation system fault indication based on the output of the differential pressure sensor being greater than a fourth threshold and the absolute value of the output of the engine intake manifold pressure sensor less the output of the barometric pressure sensor being greater than a third threshold. [12] The vehicle system of claim 7, wherein the executable instructions are executed when the engine is not idling.

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