Secondary system and method for controlling an engine

Abstract

Engine air filter diagnostic procedure, including: Indicating, via a controller, engine air filter degradation in response to an average of a pressure change at an engine air filter, wherein the pressure change at the engine air filter is based on data observed via the controller during transient airflow conditions through the engine air filter, and Adjusting one or more powertrain torque actuators to compensate for engine torque reduction associated with engine air filter degradation.

Description

Area

[0001] The present description relates to a system and method for diagnosing and mitigating the effects of a clogged engine air filter. The provided system and methods can diagnose air filter operation during steady-state and transient airflow conditions through the engine air filter. Background and brief description

[0002] An air intake of an internal combustion engine may include an air filter so that dirt cannot be sucked into an engine where the dirt could cause engine deterioration. The air filter may be positioned in an engine air intake upstream of a throttle so that air entering the engine is filtered as soon as it enters the engine air intake. One way to estimate whether or not an air filter is deteriorating is to determine an air pressure loss through the air filter for a constant amount of airflow through the air filter. However, a driver of a vehicle may frequently change the engine torque demand to meet driving conditions. Increasing driver demand torque may increase airflow through the air filter, while decreasing driver demand torque may decrease airflow through the air filter.Such torque and airflow changes can occur frequently, making establishing a consistent airflow through the air filter difficult and infrequent. As a result, reliable estimates of air filter performance may be delayed while dirt continues to accumulate in the filter. As a result, engine performance may deteriorate before conditions are established where the air filter can be reliably diagnosed. Prior art can be found in US 8 626 456 B2 and US 2016 / 0 370 799 A1.

[0003] The object of the present invention is to provide an improved method for evaluating an engine air intake air filter and a corresponding system.

[0004] The problem is solved by the features of the independent patent claims. Advantageous developments of the invention are described in the subclaims.

[0005] The inventors herein have recognized the aforementioned limitations and have developed an engine air filter diagnostic method comprising: indicating, via a controller, engine air filter degradation in response to an average of a pressure change across an engine air filter, wherein the pressure change across the engine air filter is based on data observed via the controller during transient airflow conditions through the engine air filter.

[0006] By assessing the presence or absence of engine air filter degradation in response to an average pressure drop across the engine air filter, it may be possible to provide the engineering result of evaluating an engine air filter during transient airflow conditions through the engine air filter. In particular, a mean and standard deviation of a pressure change across an engine air filter may be a basis for determining and indicating engine air filter degradation. The mean and standard deviation may be determined based on data collected during steady-state or transient airflow through the air filter. Consequently, air filter degradation may be assessed over a wider range of engine operating conditions, allowing a vehicle driver to be informed early of air filter degradation.

[0007] The present description may provide several advantages. In particular, the approach may provide earlier notification of engine air filter degradation. Additionally, the approach may provide an indication that engine performance is reduced. Furthermore, the approach may provide an estimate of the remaining useful life cycle, allowing a driver to know when an air filter is approaching a degraded state.

[0008] The foregoing advantages, as well as other advantages and features of the present description, will be readily apparent from the following detailed description when read in isolation or in conjunction with the accompanying drawings.

[0009] It should be understood that the foregoing Summary is provided to introduce, in a simplified manner, a selection of concepts that are further described in the Detailed Description. It is not intended to identify important or significant features of the claimed subject matter, the scope of which is defined solely in the claims following the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that overcome the disadvantages noted above or in any part of this disclosure. Brief description of the drawings

[0010] The advantages described herein will become more fully apparent upon reading an example of an embodiment, referred to herein as the detailed description, whether read in isolation or with reference to the drawings, in which: Fig. Figure 1 is a schematic diagram of an engine in a vehicle; The Fig. 2 and Fig. 3 Predicted pressure drop curves with mean and standard deviation for new and deteriorated air filters; Fig. 4 is a prospective progression of an exemplary engine air filter diagnostic sequence; and Fig. 5 is a method for diagnosing engine air filter deterioration. Detailed description

[0011] This description relates to diagnosing deterioration of an engine intake air filter. The engine air intake filter may be installed in a vehicle having an engine as described in Fig. 1. The air filter may exhibit operating characteristics that are reflected in the curves of the Fig. 2 and Fig. 3. An example of an engine air filter diagnosis is shown in Fig. 4. The Fig. 4 can be performed according to the procedure of Fig. 5 in cooperation with the Fig. 1 shown system.

[0012] It will be Fig. 1, in which an internal combustion engine 10 comprising a plurality of cylinders, one cylinder of which is Fig. 1, is regulated by the electronic engine controller 12. The internal combustion engine 10 includes a combustion chamber 30 and cylinder walls 32 with a piston 36 disposed therein and connected to the crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 includes a pinion shaft 98 and a pinion gear 95. The pinion shaft 98 can selectively drive the pinion gear 95 to engage the ring gear 99. The starter 96 can be mounted directly in the front of the engine or the rear of the engine. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a ground state when it is not engaged with the engine crankshaft.

[0013] The combustion chamber 30 is shown communicating with the intake manifold 44 and the exhaust manifold 48 via an intake valve 52 and an exhaust valve 54, respectively. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 may be determined by the intake cam sensor 55. The position of the exhaust cam 53 may be determined by the exhaust cam sensor 57. The intake cam 51 and exhaust cam 53 may be moved relative to the crankshaft 40.

[0014] A fuel injector 66 is shown arranged to inject fuel directly into the cylinder 30, known to those skilled in the art as direct injection. Alternatively, fuel may be injected into an intake port, known to those skilled in the art as port fuel injection. The fuel injector 66 delivers liquid fuel proportional to the pulse width of the signal from the controller 12. Fuel is supplied to the fuel injector 66 by the fuel system 175. The intake manifold 44 is shown communicating with the optional electronic throttle 62 (e.g., a butterfly valve), which adjusts a position of the throttle plate 64 to control airflow from the air cleaner 43 and air intake 42 to the intake manifold 44. The throttle 62 regulates airflow from the air cleaner 43 into the engine air intake 42 to the intake manifold 44.In one example, a two-stage high-pressure fuel system may be used to generate higher fuel pressures. 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.

[0015] A pressure difference across the air filter 43 may be determined via a differential pressure sensor 123. Alternatively, the pressure sensor 120 may determine the pressure on a downstream side of the air filter 43, while atmospheric pressure may be estimated to determine a pressure drop across the air filter 43.

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

[0017] In one example, the catalyst 70 may include multiple catalyst modules. In another example, multiple emission control devices, each including multiple modules, may be used. In one example, the catalyst 70 may be a three-way catalyst.

[0018] As shown, the engine 10 is also coupled to an electric machine 189, which may be a belt-driven integrated starter-alternator. The belt 188 mechanically couples the electric machine 189 to the crankshaft 40. Alternatively, the electric machine may be directly coupled to the crankshaft 40 or be in mechanical communication with the crankshaft 40.

[0019] In Fig. 1, the controller 12 is illustrated as a conventional microcomputer including: microprocessor unit 102, input / output ports 104, read-only memory 106 (e.g., non-volatile memory), random access memory 108, keep-alive memory 110, and a conventional data bus.The controller 12 is shown receiving various signals from sensors coupled to the engine 10 in addition to the signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 for sensing the force applied by the driver 132; a measurement of the engine's manifold pressure (MAP) from pressure sensor 121 coupled to the intake manifold 44; an engine position sensor from a Hall effect sensor 118 that senses the position of the crankshaft 40; a measurement of the mass of air entering the engine from sensor 122; a brake pedal position from brake pedal position sensor 154 when the driver 132 depresses a brake pedal 150; and a measurement of throttle position from sensor 58. Atmospheric pressure may also be sensed for processing by the controller 12 (the sensor not shown).In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of evenly spaced pulses for each revolution of the crankshaft from which the engine speed (RPM) can be determined.

[0020] Controller 12 may also transmit vehicle information to a manufacturer via radio frequency transmitter 190. A manufacturer may receive the data via remote receiver 191. Receiver 191 may communicate with the manufacturer via the Internet or other communication systems. In some examples, other engine configurations may be employed, for example, a diesel engine.

[0021] During operation, each cylinder in the internal combustion engine 10 typically undergoes 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 toward the bottom of the cylinder, increasing the volume in the combustion chamber 30. The position where the piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., 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). During the compression stroke, the intake valve 52 and the exhaust valve 54 are closed. The piston 36 moves toward the cylinder head to compress the air in the combustion chamber 30.The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., 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 a process referred to herein as injection, fuel is introduced into the combustion chamber. In a process referred to herein as ignition, the injected fuel is ignited by known ignition means such as spark plug 92, resulting in combustion. During the power stroke, expanding gases force 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 merely an example and that the timing for opening and / or closing the intake and exhaust valves may vary, for example, to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0022] The system from Fig. 1 provides an engine system comprising: an engine; an engine air intake including an air filter, a throttle, and an intake manifold; a pressure sensor disposed along the engine air intake; and a controller including executable instructions stored on non-volatile memory to indicate degradation of the air filter in response to an average pressure loss across the air filter during transient airflow through the air filter. The engine system further includes additional instructions for determining a standard deviation of a pressure loss across the air filter. The engine system further includes additional instructions for determining an average pressure loss across the air filter based on an output of the pressure sensor.The engine system further includes additional instructions for estimating a useful life of the air filter based on the average pressure drop across the air filter during temporary airflow through the filter. The engine system further includes additional instructions for estimating a useful life of the air filter based on a standard deviation of the pressure drop across the air filter during temporary airflow through the filter. The engine system further includes additional instructions for transmitting the indication to an external device via radio frequency.

[0023] In relation to Fig. 2 shows an example of a mean air pressure loss across an engine air filter (e.g. 43 from Fig. 1) versus airflow through the engine air filter. The vertical axis represents the average air pressure drop across the engine air filter, and the average pressure drop increases in a direction from the top of the graph to the horizontal axis. The horizontal axis represents airflow through the engine air filter, and the airflow rate increases in the direction of the horizontal axis arrow. The dashed line 202 represents the average pressure drop across a new engine air filter. The solid line 204 represents the average pressure drop across an air filter clogged with dirt.

[0024] It can be observed that a measurable difference in mean pressure drop occurs between the new air filter and the clogged air filter above a threshold airflow velocity. The mean difference is more pronounced at higher airflow velocities. Consequently, if the mean pressure drop across the clogged air filter at a specific airflow through the air filter divided by the mean pressure drop across the new air filter at the specific airflow is greater than a threshold, it can be determined that the clogged air filter is in a clogged condition.

[0025] In relation to Fig. 3 shows an example of a standard deviation of the air pressure loss across an engine air filter (e.g. 43 from Fig. 1) versus airflow through the engine air filter. The vertical axis represents the standard deviation of the pressure drop across the engine air filter, and the standard deviation increases in the direction of the vertical axis arrow. The horizontal axis represents airflow through the engine air filter, and the airflow rate increases in the direction of the horizontal axis arrow. The dashed line 302 represents a standard deviation of the pressure drop across a new engine air filter. The solid line 304 represents the standard deviation of the pressure drop across an air filter clogged with dirt.

[0026] It can be observed that a measurable difference in the standard deviation of the pressure drop occurs between the new air filter and the clogged air filter above a threshold airflow velocity. The difference in the standard deviation of the pressure drop is more pronounced at higher airflow velocities. Consequently, if a standard deviation of the pressure loss across the clogged air filter at a specific airflow through the air filter divided by a standard deviation of the pressure loss across the new air filter at the specific airflow is greater than a threshold value, it can be determined that the clogged air filter is in a clogged condition.

[0027] In relation to Fig. 4 shows an example of an air filter diagnostic sequence. The diagnostic sequence can be carried out via the system from Fig. 1 according to the procedure Fig. 5. The curves are temporally aligned and occur simultaneously. The vertical markers and time points T0-T2 represent relevant points in the sequence.

[0028] The first course from above of Fig. 4 is a plot of airflow through an engine air filter versus time. The vertical axis represents airflow through the engine air filter, and the airflow through the engine air filter increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the plot to the right side of the plot. The horizontal line 402 is a minimum airflow through the air filter at which diagnosing engine air filter performance is permitted. For example, air filter diagnostics may be performed when the airflow through the air filter is above or greater than an amount of threshold 402.

[0029] The second course from above Fig. Figure 4 is a graph of the engine air filter diagnostic status versus time. The vertical axis represents the engine air filter diagnostic status. The engine air filter diagnostic is active when the trace is at a higher level near the vertical axis arrow. The engine air filter diagnostic is not active when the trace is at a lower level near the horizontal axis arrow. The horizontal axis represents time, and time increases from the left side of the trace to the right side of the trace.

[0030] The third course from the top of Fig. 4 is a plot of the mean air filter pressure loss or mean air filter pressure difference versus time. The vertical axis represents the mean air filter pressure loss, and the mean air filter pressure loss increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the plot to the right side of the plot. The horizontal line 404 is an extent of the mean air filter pressure loss, above which a ratio of the mean air filter pressure loss for the clogged filter divided by the mean air filter pressure loss for a new filter indicates a degraded air filter. Thus, when the mean air filter pressure loss trace is below the threshold 404, the air filter is degraded from the perspective of the mean air filter pressure loss.

[0031] The fourth course from the top Fig. 4 is a plot of the standard deviation of the air filter pressure loss versus time. The vertical axis represents the standard deviation of the air filter pressure loss, and the standard deviation of the air filter pressure loss increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the plot to the right side of the plot. The horizontal line 406 is an extent of the standard deviation of the air filter pressure loss, above which a ratio of the standard deviation of the air filter pressure loss for the clogged filter divided by the standard deviation of the air filter pressure loss for a new filter indicates a degraded air filter. Thus, when the trace of the standard deviation of the air filter pressure loss is above the threshold 406, the air filter is degraded from the perspective of the standard deviation of the air filter pressure loss.

[0032] The fifth course from the top Fig. Figure 4 is a graph of the engine air filter degradation indication state versus time. The vertical axis represents the engine air filter degradation indication state. Engine air filter degradation is active when the trace is at a higher level near the vertical axis arrow. The engine air filter degradation indication state (e.g., an indication of engine air filter degradation is provided) is not active when the trace is at a lower level near the horizontal axis arrow. The horizontal axis represents time, and time increases from the left side of the trace to the right side of the trace.

[0033] At time T0, the air flow through the engine air filter (e.g. 43 from Fig. 1) less than threshold 402. The air filter diagnostic is not active, as indicated by the air filter diagnostic state, because the airflow through the engine air filter is below threshold 402. The mean pressure drop across the engine air filter is below threshold 404. Likewise, the standard deviation of the pressure drop across the engine air filter is below threshold 406. Engine air filter degradation is not indicated because the air filter degradation indication state is low.

[0034] At time T1, the airflow through the engine air filter increases above threshold 402. Consequently, the engine air filter diagnostics are enabled, as indicated by the air filter diagnostic state transitioning to a higher level. The mean pressure drop across the engine air filter is below threshold 404. Furthermore, the standard deviation of the pressure drop across the engine air filter is below threshold 406. Engine air filter degradation is not indicated because the air filter degradation indication state is low.

[0035] Between time T1 and time T2, the airflow through the engine air filter is maintained above threshold 402. The engine air filter diagnostics remain on, as indicated by the air filter diagnostics state, which is at a higher level. The mean pressure loss across the engine air filter increases toward threshold 404. The standard deviation of the pressure loss across the engine air filter also increases toward threshold 406, crossing threshold 406 before time T2. These parameters indicate a trend of increasing pressure loss across the engine air filter. Engine air filter degradation is not indicated because the air filter degradation indication state remains at a low level. Engine air filter degradation is not indicated because both the mean pressure loss across the engine air filter and the standard deviation of the pressure loss across the engine filter exceed thresholds 404 and 406, respectively.not exceed 406.

[0036] At time T2, the mean pressure drop across the engine air filter exceeds threshold 404, and since the standard deviation of the pressure drop across the engine air filter exceeds threshold 406, air filter degradation is confirmed, as indicated by the air filter degradation indication state transitioning to a higher level. The engine air filter diagnostic state indicates that the engine air filter diagnostics are still active.

[0037] In this way, the mean pressure loss across an engine air filter and the standard deviation of the pressure loss across the engine air filter can serve as a basis for assessing engine air filter degradation. In other words, only the mean pressure loss across the engine air filter that exceeds a threshold or only the standard deviation of the pressure loss across the engine air filter that exceeds a threshold can serve as a basis for indicating engine air filter degradation.

[0038] In relation to Fig. 5 shows an exemplary flowchart for a method for operating an engine. The method of Fig. 5 can be entered into the system from the Fig. 1 and Fig. 2 and cooperate with it. Furthermore, at least parts of the procedure may be Fig. 5 may be included as executable instructions stored on a non-volatile memory, while other parts of the method may be carried out via a controller that converts operating states of devices and actuators into the physical domain.

[0039] At 502, method 500 determines airflow through an engine air filter. In one example, airflow through the engine air filter may be determined via an output of an airflow sensor located in an engine air intake immediately downstream of the engine air filter. Method 500 proceeds to 504.

[0040] At 504, method 500 determines a pressure loss across the engine air filter. In one example, method 500 determines a pressure loss across the engine air filter via a differential or delta pressure sensor. In another example, method 500 determines the pressure loss based on subtracting a pressure downstream of the engine air filter from atmospheric pressure. Method 500 proceeds to 506.

[0041] At 506, method 500 judges whether conditions exist for evaluating the operating condition of the engine air filter. In one example, the operating conditions include the airflow through the air filter being above a threshold airflow. Method 500 proceeds to 508.

[0042] At 528, method 500 maintains the previously determined values of the engine air filter useful life and the amount of engine torque reduction based on the average pressure drop across the engine air filter at a predetermined airflow velocity through the engine air filter. Method 500 proceeds to exit.

[0043] At 508, method 500 associates the air filter pressure loss with an amount of airflow through the engine air filter. For example, the airflow through the engine air filter is sampled substantially simultaneously as the pressure loss across the engine air filter (e.g., within 500 microseconds). The pressure loss is assigned to a location on the memory corresponding to the airflow velocity sampled at the time the pressure loss is sampled. The airflow velocity through the engine air filter may be changing or in a transient state while the pressure loss across the engine air filter is being determined. The pressure loss across the engine air filter and the airflow velocity through the air filter may be sampled at a predetermined rate (e.g., every 100 milliseconds), and their values may be stored on the memory. Method 500 proceeds to 510.

[0044] At 510, method 500 estimates the mean pressure drop corresponding to the airflow through the engine air filter and the standard deviation corresponding to the airflow through the engine air filter. In one example, the mean pressure drop is determined recursively according to the following equations: μ(N)=∑i=1NxiN where N is the total number of samples at the air flow velocity through the engine air filter, µ is the mean value and x i the i -te Sample of pressure loss across the engine air filter. The standard deviation of the pressure loss across the engine air filter is determined recursively according to the following equations: For large N: µ(N+1)~µ(N)

[0045] Method 500 proceeds to 510 after determining the mean and standard deviation of the pressure drop across the engine air filter according to the airflow through the engine air filter. The mean and standard deviation for a plurality of airflows are determined and stored in memory.

[0046] At 512, method 500 determines mean pressure loss ratios and pressure loss standard deviation ratios for the plurality of airflow rates through the engine air filter. The mean pressure loss ratio for each airflow rate through the air filter is the mean pressure loss for an airflow rate through the air filter, determined at 510, divided by the mean pressure loss for the corresponding airflow rates through a new air filter. For example, the mean pressure loss ratio for airflow X through the air filter is the mean pressure loss at airflow rate of X through the air filter for the present air filter divided by the mean pressure loss at airflow rate of X through a new air filter, which can be expressed as: μmean_ratioX=μmeanXμmean_newX where µ mean_ratioXis the ratio of the mean pressure loss at a flow velocity X through the engine air filter, µ meanX the mean pressure loss across the air filter when air flows through the air filter at a speed of X (determined at 510), µ mean_newX is the mean pressure drop across a new air filter when air flows through the new air filter at a velocity of X. For a different flow velocity Y through the air filter, the mean pressure drop is expressed as: μmean_ratioY=μmeanYμmean_newY where µ mean_ratioY is the ratio of the mean pressure loss at a flow velocity Y through the engine air filter, µ meanY the mean pressure loss across the air filter when air flows through the air filter at a speed of Y (determined at 510), µ mean _newYis the mean pressure drop across a new air filter when air flows through the new air filter at a velocity of Y.

[0047] The ratio of the standard deviation of the pressure drop for each airflow velocity through the air filter is the standard deviation of the pressure drop for an airflow velocity through the air filter, determined at 510, divided by the standard deviation of the pressure drop for the corresponding airflow velocities through a new air filter. For example, the ratio of the standard deviation of the pressure drop for airflow X through the air filter is the standard deviation of the pressure drop at airflow velocity of X through the air filter for the present air filter divided by the standard deviation of the pressure drop at airflow velocity of X through a new air filter, which can be expressed as: μstd_ratioX=μstdXμstd_newX where µstd_ ratioX is the ratio of the standard deviation of the pressure loss at a flow velocity X through the engine air filter, µ stdX the standard deviation of the pressure loss across the air filter when air flows through the air filter at a speed of X (determined at 510), µ std_newX is the standard deviation of the pressure drop across a new air filter when air flows through the new air filter at a velocity of X. For a different flow velocity Y through the air filter, the standard deviation of the pressure drop is expressed as: μstd_ratioY=μstdYμstd_newY where µ std_ ratioY is the ratio of the standard deviation of the pressure loss at a flow velocity Y through the engine air filter, µ stdY the standard deviation of the pressure drop across the air filter when air flows through the air filter at a velocity of Y (determined at 510), µ std_newYis the standard deviation of the pressure drop across a new air filter when air flows through the new air filter at a velocity of Y. The mean ratio and the standard deviation ratio for each flow velocity through the air filter stored in the memory are determined. In some examples, a pressure drop standard deviation ratio and a mean pressure drop ratio are determined for a single flow velocity. In other examples, N (e.g., where N is an integer variable) pressure drop standard deviation ratios and N mean pressure drop ratios are determined for N flow velocities. Method 500 proceeds to 514.

[0048] At 514, method 500 estimates the useful life of the engine air filter. The useful life estimate may be based on a predetermined airflow velocity through the air filter, via the following equations: where %life1 is the value for the estimated service life of the air filter based on the average pressure drop at air flow of X through the engine air filter, µ actualX the actual mean pressure loss across the air filter at flow of X through the air filter for the air filter used is µ newX is the mean pressure loss across a new air filter when flowing X through the new air filter, T µX is an empirically determined threshold value of the mean pressure drop that indicates a degraded air filter for a flow velocity of X through the air filter. The service life estimation involves a second equation: where %life2 is the value for the estimated service life of the air filter based on the standard deviation of the pressure drop at air flow of X through the engine air filter, σ actualX is the actual standard deviation of the pressure loss across the air filter when flowing X through the air filter for the air filter used, σ newX is the standard deviation of the pressure loss across a new air filter when flowing at X through the new air filter, T σX is an empirically determined threshold value of the standard deviation of the pressure drop that indicates a degraded air filter for a flow velocity of X through the air filter. The estimate of the service life of the air filter is determined by: %life=min(%life1,%life2) where %life is the estimate of the useful life of the air filter and is based on the minimum of the two values %lifel and %life2. If desired, useful life values for each flow velocity through the air filter stored in memory may be determined, and the minimum of the plurality of values may be specified as the useful life of the air filter. Method 500 proceeds to 516.

[0049] At 516, method 500 reports the usage time to the driver. The usage time may be reported to the driver via a human-machine interface. Method 500 proceeds to 518.

[0050] At 518, method 500 estimates engine torque reductions for the engine based on the pressure loss across the air cleaner at a wide open throttle or the engine airflow velocity at a wide open throttle (WOT). In one example, a table or function outputs a torque value that is a torque loss when the engine is operating at WOT. The data stored in the table is empirically determined, and the table or function is indexed by engine speed and engine airflow at WOT based on data from the present air cleaner. Method 500 proceeds to 520.

[0051] At 520, method 500 adjusts powertrain torque actuators to compensate for engine torque reduction associated with the engine air filter. In one example, method 500 increases the output of an electric machine to provide a desired torque when the engine is producing less than rated torque due to a clogged air filter. The electric machine may be an integrated starter / generator, a belt-driven starter / generator, or another motor / generator in the powertrain. For example, if the driver requests 300 Nm and the engine outputs 310 Nm at the same engine speed with a new air filter, the engine may provide the driver-requested torque when the air filter is new. If the engine produces 290 Nm at the same engine speed when the air filter is partially clogged, the electric machine outputs the 10 Nm to compensate for the engine torque output.Further, at lower driver demand torque requirements, the throttle may be opened wider when the air filter is partially clogged compared to operating at the same engine speed and driver demand when the filter is new. Fuel injector and cam timing may also be adjusted to compensate for the clogged air filter, so that the driver applies the accelerator pedal in the same manner for an equal torque request during the same conditions whether the air filter is new or clogged. Method 500 proceeds to 522.

[0052] At 522, method 500 judges whether the average pressure loss across the current engine air filter at a predetermined flow rate through the current engine air filter divided by the average pressure loss across a new engine air filter at the predetermined flow rate (e.g., the average pressure loss ratio) is greater than a first threshold. Method 500 also judges whether the standard deviation of the pressure loss across the current engine air filter at the predetermined flow rate through the current engine air filter divided by the standard deviation of the pressure loss across a new engine air filter at the current predetermined air flow rate through the new engine air filter (e.g., the pressure loss standard deviation ratio) is greater than a second threshold.If the present mean pressure loss ratio is greater than the first threshold and the pressure loss standard deviation ratio is greater than the second threshold, the answer is yes and method 500 proceeds to 524. Otherwise, the answer is no and method 500 proceeds to exit.

[0053] At 524, method 500 reports the air filter degradation to the vehicle driver. The vehicle driver may be informed of the air filter degradation and service life via a human-machine interface. Method 500 proceeds to 526.

[0054] At 526, method 500 transmits the air filter degradation status and lifespan data externally to a manufacturer via a radio frequency transmitter. By transmitting the air filter degradation externally to the vehicle, a service appointment can be scheduled with a manufacturer representative so that vehicle performance can return to nominal values. Further, if desired, a new air filter can be ordered based on the data transmitted by the vehicle to the manufacturer. Method 500 proceeds to exit.

[0055] Thus, the procedure Fig. 5 provides an engine air filter diagnostic method comprising: indicating, via a controller, engine air filter degradation in response to an average pressure change across an engine air filter, the pressure change across the engine air filter being based on data observed via the controller during transient airflow conditions through the engine air filter. The method includes determining the average pressure change across the engine air filter via a differential pressure sensor. The method includes providing the data observed via the controller during transient airflow conditions through the engine air filter via a mass air flow sensor. The method includes indicating comprising transmitting data external to a vehicle in which the engine air filter is located via radio frequency.The method includes indicating a condition of engine air filter degradation to a driver via a human-machine interface. The method further includes estimating a useful life of the engine air filter based on the mean value. The method further includes estimating the useful life of the engine air filter additionally based on a standard deviation of the pressure change across the engine air filter.

[0056] The procedure from Fig.5 also provides an engine air filter diagnostic method comprising: indicating, via a controller, air filter degradation in response to an average of a pressure change across an engine air filter and a standard deviation of pressure loss across the engine air filter, wherein the pressure change across the engine air filter is based on data observed via the controller during conditions where air flows through the engine air filter. The method further comprises estimating a useful life of the engine air filter based on the average. The method further comprises estimating a useful life of the engine air filter based on the standard deviation. The method includes wherein the indication is based on the average exceeding a threshold. The method includes wherein the indication is based on the standard deviation exceeding a threshold.The procedure involves determining the mean recursively. The procedure involves determining the standard deviation recursively.

[0057] It should be noted that the example control and estimation routines included herein may be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and executed by the control system, including the controller in combination with the various sensors, actuators, and other internal combustion engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. Thus, various illustrated acts, operations, and / or functions may be performed in the illustrated order, in parallel, or in some cases, omitted.Likewise, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but rather is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, at least a portion of the described acts, operations, and / or functions may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the regulatory system.The control actions can also transform the operating state of one or more sensors or actuators in the physical domain when the described actions are performed by executing the instructions in a system including the various engine hardware components in combination with one or more controllers.

[0058] This concludes the description. A reading of this description by a person skilled in the art will reveal many changes and modifications without departing from the spirit and scope of the description. For example, this description can be applied to I3, I4, I5, V6, V8, V10, and V12 engines operating on natural gas, gasoline, diesel, or alternative fuel configurations.

Claims

[1] Engine air filter diagnostic procedure, including: Indicating, via a controller, engine air filter degradation in response to an average of a pressure change at an engine air filter, wherein the pressure change at the engine air filter is based on data observed via the controller during transient airflow conditions through the engine air filter, and Adjusting one or more powertrain torque actuators to compensate for engine torque reduction associated with engine air filter degradation. [2] The method of claim 1, wherein the mean value of the pressure change at the engine air filter is determined via a differential pressure sensor. [3] The method of claim 1, wherein the data observed via the controller during transient airflow conditions through the engine air filter is provided via a mass air flow sensor. [4] The method of claim 1, wherein adjusting one or more powertrain torque actuators comprises increasing an output of an electric machine to provide a desired torque. [5] The method of claim 1, wherein adjusting one or more powertrain torque actuators comprises opening a throttle. [6] The method of claim 1, further comprising estimating a useful life of the engine air filter based on the average value. [7] The method of claim 6, further comprising estimating the useful life of the engine air filter additionally based on a standard deviation of the pressure change at the engine air filter. [8] The method of claim 1, wherein the air filter degradation is indicated as a further response to a standard deviation of the pressure change at the engine air filter. [9] The method of claim 8, further comprising estimating a useful life of the engine air filter based on the average value. [10] The method of claim 8, further comprising estimating a useful life of the engine air filter based on the standard deviation. [11] Engine system comprising: an engine; an engine air intake including an air filter, a throttle, and an intake manifold; a pressure sensor arranged along the engine air intake; and a controller including executable instructions stored on non-volatile memory to indicate air filter degradation in response to an average pressure loss across the air filter during transient airflow through the air filter; and to adjust one or more powertrain torque actuators to compensate for an engine torque reduction associated with the engine air filter degradation. [12] The engine system of claim 11, further comprising additional instructions for determining a standard deviation of a pressure loss across the air filter. [13] The engine system of claim 11, further comprising additional instructions for determining an average pressure loss across the air filter based on an output of the pressure sensor. [14] The engine system of claim 11, further comprising additional instructions for estimating a useful life of the air filter based on the average pressure drop across the air filter during temporary airflow through the filter. [15] The engine system of claim 11, further comprising additional instructions for transmitting the indication to an external device via radio frequency.

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