Patent Description:
The present inventors have recognized, among other things, that a problem to be solved is the need for new and/or alternative monitoring and diagnostic analyses are desired. In some examples, the system mass flow and models for such flow are used to extract and monitor aging factors such as, for example, fuel injector drift, exhaust gas recirculation valve obstruction, and/or mass air flow sensor bias.

According to a first aspect of the invention, there is provided a system in accordance with Claim <NUM>. In an embodiment, the system further comprises a turbocharger having a turbine coupled to receive exhaust gas from the exhaust manifold and a compressor coupled to provide compressed air to the throttle; wherein the system monitor is configured to calculate the first pressure and first temperature upstream of the compressor.

In an embodiment, the controller is further configured to: record a plurality of calculated fuel injector drift values, determine a rate of change of the fuel injector drift, and estimate and record a percentage of useful life remaining for the fuel injector.

In an embodiment, the controller is further configured to: compare the calculated fuel injector drift to a threshold, and if the threshold is met, issue an alert for maintenance of the fuel injector.

In an embodiment, the controller is further configured to: record a plurality of MAF sensor bias values, determine a rate of change of the MAF sensor bias, and estimate and record a percentage of useful life remaining for the MAF sensor, and / or: compare the calculated MAF sensor bias to a threshold, and if the threshold is met, issue an alert for maintenance of the MAF sensor.

In an embodiment, the system may further comprise an exhaust gas recirculation (EGR) valve configured to recirculate air from the exhaust manifold back to the intake manifold, the EGR valve selectively operable between open and closed positions and subject to reduction of flow area (FEA), wherein the controller is further configured to estimate the FEA of the EGR valve using the IM pressure and IM temperature, the MAF sensor output, the FAM sensor output, the fuel injector output, the first, second and third pressures, and the first, second, and third temperatures.

In an embodiment, the controller is further configured to: record a plurality of estimated FEA values, determine a rate of change of the FEA, and estimate and record a percentage of useful life remaining for the EGR valve.

In an embodiment, the controller is further configured to: compare the estimated FEA to a threshold, and if the threshold is met, issue an alert for maintenance of the EGR valve.

The above described system may be incorporated into a hybrid electric vehicle which also includes an electric motor, wherein the electric motor is controlled using a hybrid power split optimization routine, wherein the vehicle is configured to update the hybrid power split optimization routine using the estimated fuel injector drift.

In an embodiment, the system further comprises a high pressure exhaust gas recirculation (HPEGR) valve, having an input at the engine exhaust manifold and an output at the engine intake manifold, the HPEGR valve selectively operable between open and closed positions and subject to reduction of flow area (FEA_HPEGR); a low pressure exhaust gas recirculation (LPEGR) valve, having an LPEGR input at the exhaust output and an LPEGR output coupled to the MAF sensor outlet, the LPEGR valve subject to reduction of flow area (FEA_LPEGR); wherein the controller configured to calculate each of the FEA_LPEGR and the FEA_HPEGR.

In an embodiment, the controller is further configured to: record a plurality of calculated FEA_LPEGR values, determine a rate of change of the FEA_LPEGR, and estimate and record a percentage of useful life remaining for the LPEGR.

In an embodiment, the controller is further configured to: compare the calculated FEA_LPEGR to a threshold, and if the threshold is met, issue an alert for maintenance of the LPEGR valve.

In an embodiment, the controller is further configured to: record a plurality of calculated FEA_HPEGR values, determine a rate of change of the FEA_HPEGR, and estimate and record a percentage of useful life remaining for the HPEGR.

In an embodiment, the controller is further configured to: compare the calculated FEA_HPEGR to a threshold, and if the threshold is met, issue an alert for maintenance of the HPEGR valve.

According to a second aspect of the invention, there is provided a method according to Claim <NUM>.

This overview is intended to provide an introduction to the subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation.

<FIG> shows a model of an operational control system. A control apparatus is shown at <NUM> and includes a state observer <NUM>, which feeds a set of current state variables to a low level controller <NUM>. The low level controller <NUM> calculates a solution for process parameters that can be applied to a set of actuators <NUM>, which in turn control operation of the physical plant <NUM>. The physical plant <NUM> may be, for example and without limitation, an internal combustion engine, whether diesel or gasoline. The set of actuators <NUM> may control, for example and without limitation, fuel or other injectors, variable nozzle turbine position, engine brake, after-treatment (including exhaust), throttle position, exhaust gas recirculation (EGR) valve, an electric motor (in an electric turbocharger for example, which may be controlled via pulse width modulation (PWM)), waste gate (WG) position, charge air cooler functions, position of the recirculation valve, position of a variable compressor geometry actuator; and other valves, nozzles, and components in the system.

A plurality of sensors <NUM> are provided. Sensors <NUM> may include, for example, and without limitation, sensors detecting manifold absolute pressure (MAP), mass air flow (MAF), EGR pressure, flow and temperature, turbo speed, NOx, engine speed, fuel quantity, boost pressure, etc. Additional monitored parameters may include, for example, torque output of the electric motor of an electric turbocharger, waste gate (WG) normalized opening, recirculation valve (RCV) normalized opening, and/or a variable geometry compressor position and configuration. Sensors <NUM> may in some examples also sense user inputs, such as pressure on brake or acceleration pedals and/or steering wheel position (and changes to such). Sensors <NUM> may be configured to sample the underlying parameter being sensed and provide the result of such samples to the state observer <NUM>. The state observer <NUM> may record the sensor outputs and actuator positions over time to provide history of the system operation.

The state observer <NUM> and low-level controller <NUM> may be, for example, implemented in a microcontroller configured to operate on a set of stored instructions for performing a state observation and optimization routine. In another example, an application specific integrated circuit (ASIC) may provide state observer functions, which can include the capture or accumulation of data from the actuators <NUM> and/or sensors <NUM>, which in turn may be read periodically by a microcontroller. The low-level controller <NUM> may be configured with circuitry, logic, and/or stored instruction sets for performing a control and/or optimization calculation using, for example, model predictive control (MPC) cost functions, linear quadratic regulator (LQR) control, proportional integral derivative (PID) control, or other control methods.

The low-level controller <NUM> may be integrated into, or provided separately from, an on-board diagnostics system (not shown) that can be used to record diagnostic variables and present them, as needed to the user or to store for later analysis. The low-level controller <NUM> is shown operatively linked to the overall engine control unit (ECU) <NUM>. Separate blocks <NUM>, <NUM> and <NUM> are shown, however, it should be understood that this architecture may be integrated into a single processor or microcontroller, if desired. Additional blocks may be defined for some designs including for example a health monitor or environmental control monitor. In other examples, separate ASIC, state machine(s), microcontroller(s) or microprocessors may be provided for each block <NUM>, <NUM> and <NUM>, as desired. The various blocks shown may be operatively connected by electrical and/or communications couplings, including for example a controller area network bus.

The control solution calculated by the low-level controller <NUM> is used to generate one or more outputs, which in turn are used to control the actuators <NUM> to operate the physical plant <NUM>. Generally speaking the aim may be to minimize the distance of operating variables from one or more target output values for the controllable outputs or physical plant operating characteristics. For example, the targets may be any of target turbocharger speed, target boost pressure, target pressure difference over the compressor, target air mass flow, target gas compositions, or a combination thereof. With MPC functions, the distance to target or reference values for the one or more output values (or resulting operating characteristics) is minimized, thus optimizing performance. As an example, an MPC cost function formation may be as shown in Equation <NUM>: <MAT> Where ud,k corresponds to the desired profile for the manipulated variable, uk stands for the manipulated variable, k denotes discrete time instance, and P stands for the prediction horizon of the predictive controller. In this example, yr,k and yk represent the output reference and measured value, respectively, and W<NUM> and W<NUM> specify weighting terms. The MPC cost function is minimized in operation in order to provide optimal control to the physical plant, and the low-level controller <NUM> may use MPC accordingly.

In another example, a PID control method can be used to account for each of proportional, integral, and derivative differences from a target operating point. A target operating point for PID control may use a single value, such as compressor boost pressure, or may use a plurality of values such as compressor speed and compressor boost pressure, while controlling other factors (actuator positions, for example) to direct operations to maintain such target(s). The proportional difference may indicate current state, integral difference may identify a process shift over time, and derivative difference may indicate the direction of changes in operation. With PID control, a proportional difference is minimized while monitoring to ensure that the integral and derivative differences do not indicate changing performance which may, after further iterations, cause the proportional difference to increase. The control parameters output to the actuators <NUM> are, for a PID controller, adjusted to reduce or minimize the distance of actual performance from one or more targets on an iterative basis. PID control may incorporate multiple different target operating characteristics. The low-level controller <NUM> may use PID control instead of MPC, for example. LQR control may be used instead, if desired, applying similar concepts.

The state observer <NUM>, low level controller <NUM>, or ECU <NUM> may rely on an engine model that takes into account the different features of the engine to estimate temperatures and pressures at various locations in the engine. To facilitate the above mentioned control methods (PID, MPC and/or LQR), estimated pressures and temperatures can be generated and tracked over time, as well as projected into the future within a defined time horizon, using models that are developed and validated typically under well controlled conditions such as at a test station. Specific models will vary with specific engine builds, and the terminology may vary by manufacturer. However, generally speaking, the values for estimated pressures and temperatures are thus available for use in the illustrative methods discussed below. As used herein, a "system monitor" is whichever of the state observer <NUM>, low level controller <NUM>, or ECU <NUM> (or a separate controller, if provided) that tracks and models such inferred values.

<FIG> shows an illustrative engine in schematic form. The system <NUM> includes an engine <NUM> having an (air) intake manifold <NUM>, and exhaust manifold <NUM> and a plurality of cylinders. The engine cylinders receive fuel input by fuel injectors <NUM>. Each fuel injector <NUM> is adapted to provide a variable charge of fuel for each cycle of the cylinder (generally). The amount of fuel provided is determined by a control signal. The fuel injectors <NUM> age over time, and are subject to fuel injector drift, which reflects a change in the quantity of fuel delivered relative to that predicted by the control signal.

The air system of the engine system <NUM> is shown in some detail. Ambient air is received and filtered to remove particulates by an air filter <NUM>, which is followed by a mass air flow (MAF) sensor <NUM>. The MAF sensor <NUM> determines a mass flow entering the system. The measurement reported by the MAF sensor <NUM> is subject to bias, which is affected by component tolerance, aging and/or obstructions in the MAF sensor <NUM>. For example, over time, particulates can accumulate in the MAF sensor and/or ageing of the MAF sensor can change its characteristics.

As used herein, when air passes through an element, the position before the air passes through the element is referred to as "upstream," and the position after the air passes through the element is referred to as "downstream. " For example, as shown, air passes through the air filter <NUM> and then through the MAF sensor <NUM>, therefore the air filter <NUM> is upstream of the MAF sensor <NUM>, and the MAF sensor <NUM> is downstream of the air filter <NUM>. Ambient air conditions may be sensed to determine, for example and without limitation, ambient air pressure, temperature and humidity.

In the example shown, the air passing through the MAF sensor <NUM> goes to a three way low-pressure EGR (EGR_LP) valve <NUM>, further details of which are provided below. The air out of the EGR_LP valve <NUM> is fed to a turbocharger <NUM>, which includes a compressor <NUM> and a turbine <NUM>. Using torque obtained by the turbine <NUM>, the compressor <NUM> will compress the air, raising the pressure and temperature thereof, which may also be referred to as charging the air. To enhance efficiency of the engine <NUM> (and limit temperature extremes) the air then passes through a charge air cooler (CAC) at <NUM>. Downstream of the CAC <NUM> is an adjustable choke valve (ACV), shown at <NUM>. The ACV <NUM> serves as the throttle in the system <NUM>.

The system is shown as including a recirculation valve (RCV) <NUM>, which allows charged air exiting the compressor <NUM> to recirculate back to the intake of the compressor <NUM>. The RCV is included for various purposes, mainly to prevent surge that can arise when the ACV <NUM> (throttle) is closed with the compressor <NUM> spinning at high speed. A surge condition, if it arises, causes reverse flow of air through the compressor <NUM> and can damage the compressor <NUM> or other componentry. Some examples may omit the RCV <NUM>, and its inclusion in the diagram is not limiting to this particular configuration. Using the ambient air conditions (temperature, pressure and/or humidity), the MAF sensor <NUM> output, the RCV <NUM> position, and the EGR_LP valve <NUM> position, the pressure and temperature at position <NUM>, upstream of the compressor <NUM>, can be modeled and will typically be tracked by the system monitor.

Air passing through the ACV <NUM> goes to the intake manifold <NUM>. Another set of sensors, such as temperature and pressure sensors (or other sensors measuring constituents of the air, for example) may be provided at the intake manifold <NUM>, marked as position <NUM>, as shown. The air enters the cylinders of the engine <NUM>, where combustion takes place. Following combustion, the air, now mixed with fuel (at least some of which has combusted) exits the engine at the exhaust manifold <NUM>. Pressure and temperature at location <NUM>, as shown can be modeled or inferred by the system monitor using the measured conditions at position <NUM> along with engine speed and fuel injection parameters, where the engine speed is measured by well-known magnetic measuring device, and fuel injection is obtained from the fuel injector <NUM> control signal.

The exhaust gasses from the exhaust manifold <NUM> are directed back to the turbocharger <NUM> and power the turbine <NUM>. As the exhaust air passes through the turbine <NUM>, the turbine spins and drives the compressor <NUM>. The turbine <NUM> and/or compressor <NUM> of the turbocharger <NUM> may include variable geometries, if desired. For example, turbine <NUM> may be a variable nozzle turbine (VNT). An electric motor (E-Turbo) may, optionally, be provided to enhance operation of the turbocharger <NUM>, particularly at low engine speeds where the turbine <NUM> may not provide sufficient force to the drive the compressor <NUM> to sufficiently charge the airflow. In other embodiments the turbocharger <NUM> may be omitted, or it may be replaced with, or augmented by, a supercharger, if desired and as is known in the art.

A high-pressure exhaust gas recirculation system (EGR_HP) is provided as indicated at <NUM>. The EGR_HP includes a controllable valve that allows recirculation of exhaust gasses back to the intake manifold <NUM>. The use of an EGR, generally, is well known in the art as allowing the introduction of inert gasses into the combustion chamber of the engine. In the context of a diesel engine, EGR can be useful to reduce certain environmentally harmful emissions, particularly Nitrous Oxide (NOx). EGR may also be used in a gasoline engine to reduce throttling or pumping losses and/or engine knocking.

The area of flow through a valve may be scaled by the factor of effective area (FEA). Valves, such as the EGR_LP valve <NUM> and EGR_HP <NUM>, are subject to occlusion over time and eventual blockage as particulate matter in the exhaust gasses accumulates reduce the area through which gasses can flow. FEA represents this reduction in the effective flow area. Accumulated material can also impair the ability of the valve actuator for either valve <NUM>, <NUM> to move in response to electric command signals.

A wastegate (WG) is shown at <NUM>. The WG <NUM> allows exhaust gasses to bypass the turbine <NUM> in some circumstances, such as to prevent overspeed of the turbocharger <NUM>. The WG <NUM> is included for illustration purposes and may be omitted. For example, it is common to omit the WG <NUM> when a VNT is used as turbine <NUM>. The speed of the turbocharger <NUM> can be measured, and using the turbine speed <NUM> and geometry, along with positions for EGR_HP and WG <NUM>, the temperature and pressure at position <NUM>, using as an addition input the temperature and pressure modeled at position <NUM>.

A Fuel-Air Mix (FAM) sensor <NUM> is provided to sense conditions in the exhaust gas after exiting the turbine <NUM>. The FAM sensor may include, for example and without limitation, a universal exhaust gas oxygen (UEGO) sensor, a Lambda sensor, and/or an oxygen sensor. The FAM sensor <NUM> in some examples is configured to output a measurement relative to an air-fuel equivalence ratio, usually denoted the symbol Lambda (λ) and measures the proportion of oxygen (O2) in the exhaust gasses. Pressure and/or temperature at position <NUM> may be modeled using the known geometry of the various system components and the pressure and temperatures calculated for position <NUM>, among other data inputs.

The system as shown includes an after-treatment block, illustrated at <NUM>. After treatment block <NUM> may include one or more exhaust treatment devices. For a diesel engine, for example, a selective catalytic reduction filter or Lean NOx Trap (LNT) device may be used to capture NOx emissions, other diesel oxidation catalyst (DOC) filters to capture hydrocarbon and carbon monoxide, and a Diesel Particulate Filter (DPF) may be used to capture particulate matter. A gasoline engine may include a catalytic converter, for example. In other examples, such as if the engine <NUM> is for use with other fuels, different exhaust treatment devices may be used. One or more additional sensors may be provided, such as temperature and/or pressure sensors, and any other desired sensors (such as emissions and/or particulate sensors), between the after-treatment block <NUM> to sense exhaust gasses before exiting via the muffler <NUM>.

In the example of <FIG>, a second EGR path is provided. An EGR_AC is shown at <NUM>, and comprises a heat exchanger to cool recirculated gasses, before entry to a low pressure EGR (EGR_LP), shown at <NUM>. The EGR_LP <NUM> is a valve controlled by an electric actuator. The EGR_LP <NUM> is subject to the accumulation of material therein, much like the EGR_LP <NUM> (though the gasses at this point in the system will have far less particulate matter, clogging can still arise). In this example, the EGR_LP <NUM> is a three-way valve that reduces fresh air intake as it increases exhaust gas recirculation, and vice-versa, as controlled by its actuator.

<FIG> shows an illustrative valve. The illustrative valve shown may be used anywhere in the system, though it is reflective of a common EGR valve design usable in either low pressure or high pressure positions such as shown above. Other valve designs, such as a butterfly valve, can also be used in such applications. A three-way valve may be used in some implementations, such as for the LP_EGR, as illustrated above in <FIG>. For the example shown in <FIG>, the valve housing <NUM> has an opening at <NUM> exposed to the exhaust gas stream. A plunger <NUM> is moveable up or down under the control of an actuator <NUM>, allowing recirculation of exhaust gasses as shown at <NUM> to the system intake side through opening <NUM>. The tendency is for obstructing material to accumulate around the plunger <NUM> and/or at the opening <NUM> exposed to the exhaust. Over time, the obstructing material reduces the available area for gas to flow, that is, the FEA is reduced, reducing flow even when the plunger <NUM> is retracted from the opening at <NUM>.

For the valve shown in <FIG>, or any other valve design, the passage of gas can be impeded by clogging or fouling over time. FEA for such devices indicates how much of the original flow area remains unobstructed. As a FEA decreases, the valve ceases to provide the desired degree of flow and/or may no longer actuate as commanded. In addition, the EGR flow model that the system control relies upon to determine EGR valve positions becomes biased. Eventually, the valve has to be cleaned or replaced. Thus, FEA is a useful variable to measure or otherwise determine for maintenance purposes.

<FIG> shows a flow measurement device which can be used as a mass air flow (MAF) sensor. A tube <NUM> has within it a hot wire anemometer measurement device, with a filament <NUM> having current or voltage applied across from electrical connectors <NUM>, <NUM>. In an analog application, a Wheatstone bridge circuit may be coupled to the connectors <NUM>, <NUM> to monitor changes in the resistance encountered by the electrical signal passed through the filament <NUM>. Such changes reflect the mass of the gasses <NUM> flowing through the tube <NUM>. Other flow measurement devices with other designs are also known, including, for example, flow obstructing measurement devices such as Venturi tubes, orifice plates and/or nozzle devices.

Referring again to the system in <FIG>, several components are subject to aging over time. Aging factors that can affect system performance and necessitate maintenance may include MAF sensor bias, in which the measurements generated by the MAF sensor become inaccurate. Another aging factor is the FEA for each of the EGR valves, which affects mass flow relative to the expected flow as the opening through which gasses may flow becomes constricted. Still another aging factor is fuel injector drift, in which the actual quantity of fuel which is injected changes relative to an expected value. If these changes/biases are not detected and compensated, there may be a loss of system performance such as, for example, changes in emissions. Maintenance for each of these items may include any of cleaning, repair, or replacement.

At a system level, in an example, a system as shown above in <FIG> includes a plurality of available internal measurement devices for mass flow, temperature and pressure, and is generally sealed relative to the atmosphere except for intentional inputs and outputs as shown. The system may also be modeled by its manufacturer (or other person/entity) to allow pressures and temperatures to be estimated by inference and by reference to known actuator positions and other measurements. With the system sealed, mass flow into and out of the system must be equal. Absent leaks, the mass of air input that passes through the MAF sensor <NUM> plus the fuel input by the fuel injectors <NUM> must equal the mass exiting via the muffler <NUM>. As noted, however, the MAF sensor <NUM> and the fuel injectors <NUM> are subject to bias and drift, respectively. Within the system, at least with respect to mass flow, there are at least two additional factors of high interest: FEA for each of the EGR valves <NUM>, <NUM>. An illustrative example combines analysis of these factors together, enabling a new and innovative analysis of several components allowing system maintenance, operation, and health to be optimized. More particularly, the following examples show how the available system measurement devices and modeling can be used to determine each of the MAF sensor drift, the fuel injector drift, and functional operation of the EGR valves.

The total mass flow into the engine at the intake manifold can be linked to the measured mass flow at the system air input and the EGR mass flow as {WENG = WMAF,c + WEGR}, where WMAF,c is the corrected MAF sensor flow. The corrected MAF sensor flow can be modeled as {WMAF,c = WMAF + bA}, in which WMAF is the actual measured MAF, and bA is the MAF sensor bias. Regarding WEGR, for those systems having two EGR valves, the value can be understood as {WEGR = WEGR,<NUM> + WEGR,<NUM>}. In this formula and those that follow, for consistency the high pressure EGR valve is referenced as EGR,<NUM> and the low pressure EGR valve is EGR,<NUM>.

Next, the difference between the total mass flow into the engine, WENG, and the MAF measurement, WMAF, can be understood from Equation <NUM>: <MAT> Where:.

In context, the FEA estimates, Cv1 and Cv2 can be rated to a range of <NUM> to <NUM>, with <NUM> indicating a clean or new valve, and <NUM> indicating complete occlusion, such that as each degrades, the amount of mass flow through each valve is reduced in the above equation.

The rate of mass flow at the engine intake manifold couples the EGR_HP flow to that of the throttle (ACV <NUM> in <FIG>), and can be understood from Equation <NUM>: <MAT> The rate of change of intake manifold pressure can then be calculated from the mass flows as illustrated in Equation <NUM>: <MAT> Where κ is the isentropic exponent of air, Vi is the intake manifold volume, TENG is the measured temperature at the intake manifold, and TTHR is the modeled temperature at the throttle.

In addition to the mass flow into the engine from the combined throttle and high pressure EGR, the fuel injectors add further mass input by injecting a quantity of fuel in each cylinder. Downstream of the engine, in the exhaust, the FAM sensor (<NUM> in <FIG>) provides a measure of the mass ratios in the exhaust gas escaping the system. The output of the fuel injectors is subject to drift, bF. Equation <NUM> ties the system output to the system input: <MAT> Where λ(t) is the FAM sensor's measurement of the air-fuel ratio, WF is the uncorrected mass flow of fuel, and Lth is the stochiometric constant. The λ(t) term provides a scaled output of air-to-fuel ratio by mass, and the inclusion of Lth (and/or one or more additional constants) is used here to normalize the output in terms of the determined air mass. That is, knowing the air-fuel ratio, multiplying by the fuel input, gives the air input assuming an otherwise closed system, with two drift terms included in the formula.

Taking the above equations together, a configuration of an extended Kalman filter (EKF) discrete time dynamic can be built using the standard EKF approach to discrete time dynamics - that is, in discrete math, xk+<NUM> = fk(xk, uk, zk), yielding the following set of equations: <MAT> <MAT> <MAT> <MAT> <MAT> And the state vector can be defined as: <MAT> Two flow models, each providing a measure of MAF sensor bias, fuel injection drift, and EGR FEA, and one measurement pressure model result: <MAT> <MAT> <MAT> Here, y<NUM>,k is the total (raw or uncorrected) EGR flow model, y<NUM>,k is the intake manifold pressure model, and y<NUM>,k is the mass air flow model for the MAF sensor. As a result, using the limited set of inputs, the measured MAF into the system, knowledge of prior estimates of the two EGR FEA, and the two EGR valve positions, each of the current MAF Sensor Bias, Fuel Injector Drift, and EGR FEA can be calculated.

The above example includes inputs and analytics for a system having both an EGR_HP and an EGR_LP. Some examples may omit one or the other of the EGR flow paths. As an example, a diesel engine may omit the LP_EGR, while a gasoline engine may omit the HP_EGR. In other examples, both EGR valve paths can be included in gasoline, diesel, or other fuel engines. If so, the above equations apply in the same way, except that the EGR mass flow for whichever path is omitted is replaced by zero.

Once calculated, one or more of these values can then be recorded in the on-board memory and/or communicated from the vehicle to an external database, such as a central repository of information for a fleet of vehicles or a manufacturer's database. Various decisions can also be made, as shown in <FIG>.

<FIG> shows a first example application of the methods and systems disclosed herein. The method <NUM> includes configuration of the initial vector and system inputs at <NUM>. Step <NUM> may include, for example, obtaining and/or entering information regarding the system components in use, including configuration of the MAF sensors, the EGR Valves, size/volume of the engine intake manifold, the UEGO, and the fuel injectors. The method includes performing system monitor functions during operation of the engine, as indicated at <NUM>. Monitor functions <NUM> includes obtaining data related to the output of pressure and temperature sensors, the MAF sensor, and settings for the EGR valves and fuel injectors as the engine is operated, as well as inferring and tracking pressure and temperature at various points in the system using a model.

Next, as indicated at <NUM>, the method obtains an estimated FEA, or more than one estimated FEA. The estimated FEA obtained at <NUM> may be that of an EGR valve, whether high pressure or low pressure, for example. The estimated FEA is then compared to a threshold, as indicated at <NUM>, where the threshold sets a lower bound for the FEA in some examples. The threshold may, for example, require that the estimated FEA indicate no more than some predetermined percentage of available flow area (<NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or other value) is blocked. If the threshold is crossed at <NUM>, the system sets a flag for maintenance at <NUM>. Step <NUM> may simply include storing or updating a value in memory, or may instead annunciate a need for maintenance, such as by illuminating a check engine light or activating another alert to a user. Step <NUM> may also or instead comprise issuing a communication from the vehicle or system to a central repository for a fleet of vehicles or an OEM database, for example. The maintenance may include, for example, cleaning or replacing one or more components.

If the FEA does not indicate an immediate need for maintenance in block <NUM>, the method can return to block <NUM> and await a next iteration. For example, the monitor functions in block <NUM> may be performed at intervals, such as once a second, minute, hour or day, or once or more per trip. In some examples, the system may also determine a rate of change of the FEA, as indicated at block <NUM>. If the rate of change in estimated FEA exceeds another threshold, this may again prompt a flag for maintenance. The rate of change may also be used to estimate remaining useful life for the EGR valve(s), as indicated at <NUM>. The remaining useful life may be reported, either by communication to a central repository, or during a maintenance visit, and may be used to schedule maintenance.

The values stored throughout the process, including the FEA estimates, may also be stored for purposes of troubleshooting. At a maintenance visit, the vehicle system may be electronically polled by coupling to the engine control unit to download diagnostic trouble codes (DTCs) generated during operation. Stored FEA estimates may be used to aid in ruling in, or ruling out, potential root causes for reported DTCs. In addition, if a health monitor is included in the system, the recorded FEA information may be used by the system health monitor to optimize or adjust engine performance and operation, using methods and systems disclosed in <CIT> and titled HEALTH CONSCIOUS CONTROLLER.

<FIG> shows another example application of the methods and systems disclosed herein. The method <NUM> includes configuration of the initial vector and system inputs at <NUM>. Step <NUM> may include, for example, obtaining and/or entering information regarding the system components in use, including configuration of the MAF sensors, the EGR Valves, size/volume of the engine intake manifold, the UEGO, and the fuel injectors. The method then performs system monitor functions during operation of the engine, as indicated at <NUM>. System monitor functions <NUM> includes obtaining data related to the output of pressure and temperature sensors, the MAF sensor, and settings for the EGR valves and fuel injectors as the engine is operated, as well as inferring and tracking pressure and temperature at various points in the system using a model.

Next, as indicated at <NUM>, the method obtains an estimated MAF Sensor Bias. The estimated MAF Sensor Bias obtained at <NUM> is then compared to a threshold, as indicated at <NUM>, where the threshold sets an upper bound for the MAF Sensor Bias in some examples. The threshold may, for example, require that the estimated MAF Sensor Bias indicate no more than some predetermined amount of change, such as <NUM>% to <NUM>%, or more or less, from nominal or initial calibrated values, or relative to an expected or estimating aging trend (that is, relative to a model for MAF Sensor Bias developed for the MAF Sensor itself to the extent one is available). If the threshold is crossed at <NUM>, the system sets a flag for maintenance at <NUM>. Step <NUM> may simply include storing or updating a value in memory, or may instead annunciate a need for maintenance, such as by illuminating a check engine light or activating another alert to a user. Step <NUM> may also or instead comprise issuing a communication from the vehicle or system to a central repository for a fleet of vehicles or an OEM database, for example. The maintenance may include, for example, cleaning or replacing one or more components.

If the MAF Sensor Bias does not indicate an immediate need for maintenance in block <NUM>, the method can return to block <NUM> and await a next iteration. For example, the monitor functions in block <NUM> may be performed at intervals, such as once a second, minute, hour or day, or once or more per trip. In some examples, the system may also determine a rate of change of the MAF Sensor Bias as indicated at block <NUM>. If the rate of change in estimated MAF Sensor Bias exceeds another threshold, this may again prompt a flag for maintenance. The rate of change may also be used to estimate remaining useful life for the MAF Sensor, as indicated at <NUM>. The remaining useful life may be reported, either by communication to a central repository, or during a maintenance visit, and may be used to schedule maintenance.

<FIG> shows another example application of the methods and systems disclosed herein. The method <NUM> includes configuration of the initial vector and system inputs at <NUM>. Step <NUM> may include, for example, obtaining and/or entering information regarding the system components in use, including configuration of the MAF sensors, the EGR Valves, size/volume of the engine intake manifold, the UEGO, and the fuel injectors. The method then performs system monitor functions during operation of the engine, as indicated at <NUM>. System monitor functions <NUM> includes obtaining data related to the output of pressure and temperature sensors, the MAF sensor, and settings for the EGR valves and fuel injectors as the engine is operated as well as inferring and tracking pressure and temperature at various points in the system using a model.

Next, as indicated at <NUM>, the method obtains an estimated Fuel Injector Drift. The estimated Fuel Injector Drift obtained at <NUM> is then compared to a threshold, as indicated at <NUM>, where the threshold sets an upper bound for the Fuel Injector Drift in some examples. The threshold may, for example, require that the estimated Fuel Injector Drift indicate no more than some predetermined amount of drift, such as <NUM>% to <NUM>%, or more or less, from nominal or initial calibrated values, or relative to a model of degradation/drift for the Fuel Injectors themselves (to the extent such a model is available). If the threshold is crossed at <NUM>, the system sets a flag for maintenance at <NUM>. Step <NUM> may simply include storing or updating a value in memory, or may instead annunciate a need for maintenance, such as by illuminating a check engine light or activating another alert to a user. Step <NUM> may also or instead comprise issuing a communication from the vehicle or system to a central repository for a fleet of vehicles or an OEM database, for example. The maintenance may include, for example, cleaning or replacing one or more components.

If the Fuel Injector Drift does not indicate an immediate need for maintenance in block <NUM>, the method can return to block <NUM> and await a next iteration. For example, the system monitor functions in block <NUM> may be performed at intervals, such as once a second, minute, hour or day, or once or more per trip. In some examples, the system may also determine a rate of change of the Fuel Injector Drift as indicated at block <NUM>. If the rate of change in estimated Fuel Injector Drift exceeds another threshold, this may again prompt a flag for maintenance. The rate of change may also be used to estimate remaining useful life for the Fuel Injectors, as indicated at <NUM>. The remaining useful life may be reported, either by communication to a central repository, or during a maintenance visit, and may be used to schedule maintenance.

The values stored throughout the processes in <FIG>, including the FEA estimates, MAF Sensor Bias, and/or fuel injector drift, may also be stored for purposes of troubleshooting. At a maintenance visit, the vehicle system may be electronically polled by coupling to the engine control unit to download diagnostic trouble codes (DTCs) generated during operation. Stored FEA estimates, MAF Sensor Bias, and/or fuel injector drift may be used to aid in ruling in, or ruling out, potential root causes for reported DTCs. In addition, if a health monitor is included in the system, the recorded FEA, MAF Sensor Bias, and/or fuel injector drift information may be used by the system health monitor to optimize or adjust engine performance and operation, using methods and systems disclosed in <CIT> and titled HEALTH CONSCIOUS CONTROLLER.

In some examples, the calculation of MAF Sensor Bias, Fuel Injector Drift, and/or HP or LP EGR FEA, is performed with the engine system fully operational. Such examples are in contrast with alternatives in which the engine, or one or more components of the engine, are disabled. For example, <CIT> discloses an approach to diagnosing an EGR status, such as identifying a clogged valve, by forcing air through the EGR valve with the engine off, and/or <CIT>, in which fuel injector performance is determined by disabling fuel injectors one at a time during engine idling. In other examples, one or more engine features may be disabled or otherwise modified from ordinary operation, or may be operated in a controlled state, while performing any of the above described analyses.

<FIG> shows an example in the context of a hybrid vehicle which combines electric drive with a fuel-based drive. Optimization is used in hybrid vehicle engine control to maximize fuel efficiency. As the vehicle ages, and particularly as the fuel injectors age, the optimization models either become less accurate or must be updated using, for example, an assumed or modeled fuel injector drift. In an illustrative implementation, however, the calculated fuel injector drift can be applied, thereby enhancing the optimization routine. In the example of <FIG>, power split optimization is performed at block <NUM>. During operation of the internal combustion engine, system monitor functions are performed at <NUM> (similar to blocks <NUM>, <NUM>, and <NUM> described above), and the above methods are used to estimate fuel injector drift at <NUM>. The estimated fuel injector drift is then used to update one or more terms related to the fuel injector operation in the power split optimization calculation as indicated at <NUM>. For example, current fuel consumption, accumulated fuel consumption, and/or the fuel consumption map may be updated. The result is an enhanced approach to the power split optimization.

The drawings show, by way of illustration, specific embodiments. " Moreover, in the claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic or optical disks, magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description.

Claim 1:
A system comprising:
an engine (<NUM>) comprising at least one cylinder, at least one fuel injector (<NUM>), an intake manifold and an exhaust manifold (<NUM>), wherein the at least one fuel injector is configured to inject a mass of fuel to the cylinder, subject to fuel injector drift;
an air intake comprising a mass air flow (MAF) sensor (<NUM>) having an inlet and an outlet that generates a MAF sensor output subject to MAF sensor bias;
a fuel-air mix (FAM) sensor (<NUM>) having a FAM sensor output;
a throttle (<NUM>) positioned between the air intake and the engine intake manifold;
an ambient pressure sensor and an ambient temperature sensor each having an output;
an intake manifold (IM) pressure sensor and an IM temperature sensor configured to sense pressure and temperature respectively at the intake manifold;
a system monitor configured to calculate each of the following using a model of the engine and the ambient pressure sensor and ambient temperature sensor outputs:
a first pressure and a first temperature downstream of the MAF sensor, also using the MAF sensor output;
a second pressure and a second temperature at the exhaust manifold, also using a pressure sensed by the IM pressure sensor, a temperature sensed by the IM temperature sensor, engine speed and the mass of fuel;
a third pressure and a third temperature at the FAM sensor, also using the second pressure and the second temperature at the exhaust manifold;
a controller configured to calculate each of fuel injector drift and MAF sensor bias using the IM pressure and IM temperature, the MAF sensor output, the FAM sensor output, the mass of fue1 , the first, second and third pressures, and the first, second, and third temperatures.