Systems and methods for improving fuel vapor filter canister purge operations in a phev

Abstract

The present disclosure provides "Systems and methods for improving fuel vapor filter canister purge operations in PHEVs." Methods and systems are provided for reasonably accounting for a hydrocarbon sensor in a hybrid vehicle for feedforward air-fuel ratio control during fuel vapor filter canister purge events. In one example, a method includes directing blow-by gas from a crankcase of an engine of the vehicle to an intake manifold of the engine, and then to a fuel vapor storage filter canister; and indicating whether the hydrocarbon sensor is operating as expected based on a magnitude of a response of the hydrocarbon sensor during the directing. In this way, the hydrocarbon sensor can be diagnosed under conditions where the canister is substantially free of fuel vapor and engine run time is limited.

Description

Technical Field

[0001] This specification generally relates to methods and systems for controlling the engine of a vehicle to rationalize the use of hydrocarbon sensors for feedforward control of fuel vapor canister extraction operations in plug-in hybrid electric vehicles. Background Technology

[0002] Automotive fuel, primarily gasoline, is a volatile liquid that readily evaporates in response to diurnal variations in ambient temperature. Therefore, the fuel contained in a vehicle's fuel tank is a major source of potential evaporative emissions of hydrocarbons into the atmosphere. These emissions from vehicles constitute what is technically known as 'evaporative emissions'.

[0003] The industry's response to this potential problem is to incorporate evaporative emission control systems (EVAP) into vehicles to prevent fuel vapors from being emitted into the atmosphere. EVAP systems include fuel vapor filters containing adsorbent carbon that captures these fuel vapors and feeds them back to the vehicle's engine intake manifold for combustion during filter extraction operations, thereby reducing evaporative emissions from the vehicle.

[0004] Hybrid electric vehicles, including plug-in hybrid electric vehicles (PHEVs), present specific challenges for effectively controlling evaporative emissions using this system. While various forms of hybrid vehicles have been proposed and introduced, these designs share the characteristic of providing an internal combustion engine as a backup for the electric motor. The main power source is the electric motor, and careful attention must be paid to charging cycles that may result in operating curves where the engine operates only for short periods. Systems where the engine operates only once or twice every few weeks are not uncommon. Carbon filter extraction only occurs when the engine is running, and without extraction, carbon particles can become saturated, allowing hydrocarbons to escape into the atmosphere and cause pollution.

[0005] Furthermore, PHEVs have a sealed fuel tank designed to withstand pressure and vacuum differences within the tank due to daytime ambient temperature variations. Because the PHEV's fuel tank is sealed, daytime and operational loss vapors are contained within it, primarily when the fuel tank is opened for refueling. After the filter canister is loaded from a refueling event, fuel vapors can be extracted from the canister via an extraction event commanded by the engine's controller in subsequent driving cycles. Once the filter canister is emptied of fuel vapors, it can thus remain clean until the next refueling event, which could be a considerable amount of time if primarily operated in pure electric mode.

[0006] For extraction operations, some strategies utilize "feedforward" control to maintain the stoichiometric air-fuel ratio for engine combustion. This strategy may rely on a hydrocarbon sensor placed in the extraction line between the filter canister and the engine to measure the concentration of vapors extracted from the filter canister. Based on this concentration, the engine refueling strategy can be controlled to reduce fuel injector pulses in order to maintain the stoichiometric air-fuel ratio during extraction events, thereby reducing the risk of engine lag and / or engine stall due to extraction events. Therefore, the engine control strategy expects to know whether the hydrocarbon sensor is operating as desired.

[0007] While a hydrocarbon sensor can be reasonably characterized during a refueling event by simply indicating whether it responds to fuel vapors drawn from the canister, diagnosing the hydrocarbon sensor after canister cleaning until a subsequent refueling event can be challenging. As discussed above, when the vehicle is operating in pure electric mode, a subsequent refueling event may not occur for an extended period, and therefore, the hydrocarbon sensor may remain undiagnosed for a considerable time. During this period, if the hydrocarbon sensor deteriorates, subsequent refueling events could lead to engine lag / stall, which could negatively impact customer satisfaction and potentially cause engine degradation over time. Therefore, a method is needed to diagnose the hydrocarbon sensor used for feedforward air-fuel ratio control during fuel vapor storage canister refueling. Summary of the Invention

[0008] The inventors of this paper have recognized the problems mentioned above and have developed systems and methods to address them. In one example, one method involves guiding blow-by gas from the crankcase of a vehicle's engine to the engine's intake manifold and then to a fuel vapor storage filter located in the vehicle's evaporative emission system; and indicating, based on the response of a hydrocarbon sensor during the guidance, whether a hydrocarbon sensor used for feedforward air-fuel ratio control during extraction from the fuel vapor storage filter is operating as desired. In this way, such a hydrocarbon sensor can be reasonably described under the conditions that the fuel vapor storage filter is clean and the vehicle is frequently operated in a purely electric operating mode.

[0009] In one example, directing blow-by gas may include a key-off condition after the engine has been in operation to propel the vehicle in a driving cycle. Directing blow-by gas to the intake manifold may also include opening a crankcase forced valve located in a line connecting the crankcase to the intake manifold. In one example, the crankcase forced valve may include an electronically actuated valve under the control of the vehicle's controller and may be commanded to fully open to direct blow-by gas to the intake manifold. In another example, the crankcase forced valve may include a passively mechanically actuated valve controlled to a minimum restraint position such that blow-by gas can be directed to the intake manifold.

[0010] By reasonably explaining the hydrocarbon sensor as described above and further detailed below, adverse conditions such as engine lag and / or stall can be reduced or avoided in response to extraction operations, which in turn can increase engine life and customer satisfaction.

[0011] The above and other advantages and features of this specification will become apparent when the following specific embodiments are considered alone or in conjunction with the accompanying drawings.

[0012] It should be understood that the above description of the invention is provided to introduce a series of concepts in a simplified form, which will be further described in the detailed embodiments. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed embodiments. Furthermore, the claimed subject matter is not limited to implementations that address any of the shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0013] Figure 1 A schematic diagram of an engine is shown, including an engine crankcase forced ventilation (PCV) system, a fuel system, and an evaporative emission system.

[0014] Figure 2 Show Figure 1 A schematic diagram of another example of an evaporative emission system depicted at the site.

[0015] Figures 3A to 3C An exemplary configuration of a mechanical PCV valve is depicted, the configuration depending on... Figure 1 The pressure in the intake manifold of the engine is depicted.

[0016] Figure 4 A high-level exemplary method for reasonably illustrating a hydrocarbon sensor is described, the hydrocarbon sensor being used to detect hydrocarbons located in... Figure 1 The fuel vapor filter canister in the described evaporative emission system is used for extraction control.

[0017] Figure 5 Depicting according to Figure 4 The method is used to reasonably illustrate an exemplary timeline of a hydrocarbon sensor used for extraction control.

[0018] Figure 6 Depicting according to Figure 4 This method reasonably illustrates another exemplary timeline of hydrocarbon sensors used for extraction control. Detailed Implementation

[0019] The following description relates to systems and methods for diagnosing hydrocarbon sensors used in plug-in hybrid electric vehicles (PHEVs) for feedforward air-fuel ratio control during fuel vapor storage tank extraction. While the systems and methods focus on PHEVs, it is understood that the methodology is equally applicable to hybrid electric vehicles (HEVs) with sealed fuel tanks. Therefore, Figure 1 An exemplary engine system for a PHEV is depicted, including a fuel system, an evaporative emission system, a crankcase forced ventilation (PCV) system, a means for plugging into the power grid, and a motor / generator. In short, diagnostics of a hydrocarbon sensor may include directing blow-by gas from the engine's crankcase to the engine's intake manifold via the PCV system, and then directing the blow-by gas in the intake manifold to the evaporative emission system for storage in a fuel vapor storage filter canister, wherein the directing guides the blow-by gas through the hydrocarbon sensor, thereby enabling reasonable description of the hydrocarbon sensor. Directing the blow-by gas to the filter canister may include activating a vacuum pump positioned between the filter canister and the atmosphere. In one example, the vacuum pump includes an emission level check monitor (ELCM) positioned in the ventilation duct. In another example, such as... Figure 2 As depicted, the vacuum pump can be positioned in a vacuum pump duct parallel to the ventilation line. To direct blow-by gas from the crankcase to the intake manifold, a PCV valve positioned within the PCV system can be opened. In some instances, the PCV valve may include a passively actuated mechanical PCV valve (mPCV valve), while in other instances, the PCV valve may include an electrically actuated (e.g., electronically actuated) PCV valve (ePCV valve). Therefore, Figures 3A to 3C Examples illustrating how the pressure in the intake manifold relates to the open / closed state of the mPCV valve are described. Figure 4 An exemplary method for reasonably illustrating a hydrocarbon sensor is described. Figures 5 to 6 Showing the use of according to Figure 4 The method is used to reasonably illustrate an exemplary timeline of a hydrocarbon sensor, in which Figure 5 The timeline includes the use of ePCV valves, and in which Figure 6 The timeline includes the use of the mPCV valve.

[0020] Turn now Figure 1A schematic diagram of a hybrid vehicle system 6 is presented, which can obtain propulsion power from an engine system 10 and / or an on-board energy storage device (such as a battery system (see below)). An energy conversion device (such as a generator (see below)) can be operated to absorb energy from vehicle motion and / or engine operation, and then convert the absorbed energy into an energy form suitable for storage by the energy storage device. The engine system 10 may include a multi-cylinder internal combustion engine, which may be included in the propulsion system of the motor vehicle. The engine 10 may be controlled at least in part by a control system including a controller 12, and by input from a vehicle driver 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP.

[0021] Engine 10 may include a lower portion of an engine block, typically designated 26, which may include a crankcase 28 surrounding a crankshaft 30, with an oil trap 32 positioned below the crankshaft. A filler port 29 may be disposed in the crankcase 28 to supply oil to the oil trap 32. The filler port 29 may include a filler cap 33 to seal the filler port 29 when the engine is in operation. A dipstick tube 37 may also be disposed in the crankcase 28 and may include a dipstick 35 for measuring the oil level in the oil trap 32. An oil temperature sensor 51 may be included in the crankcase 28 and may monitor the temperature of the oil in the oil trap 32. Additionally, the crankcase 28 may include a plurality of other orifices for servicing components within the crankcase 28. These orifices in the crankcase 28 may remain closed during engine operation, allowing the crankcase ventilation system (described below) to operate during engine operation.

[0022] The upper portion of the engine block 26 may include a combustion chamber (i.e., a cylinder) 34. The combustion chamber 34 may include a combustion chamber wall 36 in which a piston 38 is positioned. The piston 38 may be coupled to a crankshaft 30 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. The combustion chamber 34 may receive fuel from a fuel injector 45 (configured herein as a direct fuel injector) and intake air from an intake manifold 44 located downstream of a throttle valve 42. The engine block 26 may also include an engine coolant temperature (ECT) sensor 46 input to an engine controller 12.

[0023] In some embodiments, each cylinder of the engine 10 may include a spark plug 53 for initiating combustion. An ignition system (not shown) may, in a selected operating mode, provide an ignition spark to the cylinder 34 via the spark plug 53 in response to a spark advance signal from a controller.

[0024] A throttle valve 42 may be positioned in the engine intake port to control airflow into the intake manifold 44, and, for example, upstream of the throttle valve 42 may be a compressor 50, immediately preceding a booster air cooler 52. The throttle valve 42 may include, for example, an electrically actuated throttle valve. An air filter 54 may be positioned upstream of the compressor 50 and may filter fresh air entering the intake passage 13. Intake air may enter the combustion chamber 34 via an electrically actuated intake valve system 40. Similarly, combusted exhaust gas may exit the combustion chamber 34 via an electrically actuated exhaust valve system 41. In an alternative embodiment, one or more of the intake and exhaust valve systems may be cam-actuated. During the period when the compressor bypass valve (CBV) 55 is open, intake air may bypass the compressor 50 via a compressor bypass duct 56. In this way, pressure buildup at the compressor inlet can be reduced.

[0025] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 34 is shown to include at least one intake valve 94 and at least one exhaust valve 95 located in the upper region of cylinder 34. In some instances, the valves of cylinder 34 may be deactivated via a hydraulically actuated lifter coupled to a valve pushrod or via a cam profile switching mechanism that uses an unlifted cam lobe for the deactivated valve. Other valve deactivation mechanisms, such as electrically actuated valves, may also be used. In one instance, engine 10 may include a variable displacement engine (VDE), wherein each cylinder of engine 10 may be selectively deactivated, where deactivation means the ability of a controller to command both the intake and exhaust valves of a particular cylinder to close, thereby sealing the particular cylinder. If fuel injection is also stopped, this action may result in the particular cylinder essentially being air-springed. Thus, as depicted herein, in one embodiment, the deactivation of intake valve 94 may be controlled by a first VDE actuator 83, while the deactivation of exhaust valve 95 may be controlled by a second VDE actuator 84. In an alternative embodiment, a single VDE actuator can control the deactivation of both the intake and exhaust valves of a deactivatable cylinder. In other embodiments, a single-cylinder valve actuator deactivates multiple cylinders (both intake and exhaust valves) (e.g., all cylinders in a deactivated cylinder bank), or different actuators can control the deactivation of all intake valves, while another different actuator controls the deactivation of all exhaust valves of the deactivated cylinders in the cylinder bank. It should be understood that if the cylinder is a non-deactivatable cylinder of a VDE engine, the cylinder may not have any valve deactivation actuators. Cylinder 34 may have a compression ratio, which is the ratio of the volume when piston 38 is at bottom dead center to that at top dead center. Typically, the compression ratio is in the range of 9:1 to 10:1. However, in some instances where different fuels are used, the compression ratio may be increased. This may occur, for example, when using higher octane fuels or fuels with higher latent enthalpy of vaporization. If direct injection is used, the compression ratio may also be increased due to the effect of direct injection on engine knock.

[0026] In some instances, the first intake oxygen sensor 43a (first IAO2 sensor) may be located downstream of the throttle valve 42. Additionally, in some instances, the intake system hydrocarbon (AIS HC) trap 47 may be located downstream of the air filter 54 but upstream of the compressor 50. Furthermore, in some instances, the second intake oxygen sensor 43b (second IAO2 sensor) may be located upstream of the throttle valve 42. The second intake oxygen sensor 43b may constitute an intake oxygen sensor for purposes such as exhaust gas recirculation (EGR) and may be used in vehicles with direct fuel injection, such as turbocharged direct injection (GTDI) engines.

[0027] Exhaust combustion gases exit the combustion chamber 34 via an exhaust duct 60 located upstream of the turbine 62. An exhaust sensor 64 may be mounted upstream of the turbine 62 along the exhaust duct 60. The turbine 62 may be equipped with an exhaust valve (not shown) bypassing it. The exhaust sensor 64 may be a suitable sensor for providing an indication of the exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (Universal or Wide Range Exhaust Oxygen), a dual-state oxygen sensor or EGO, HEGO (Heated EGO), NOx, HC, or CO sensor. The exhaust sensor 64 may be connected to the controller 12. The engine exhaust port 60 may also include one or more emission control devices 63 mounted in a closely connected position. The one or more emission control devices may include a three-way catalytic converter, a lean NOx trap, a diesel particulate filter, an oxidation catalyst, etc. In some instances, multiple exhaust sensors may be positioned both upstream and downstream of the emission control device 63. In some instances, an electric heater 119 may be coupled to the emission control device and may be under the control of the controller. In some instances, such an electric heater may be used to raise the temperature of the emission control device to the ignition temperature, or alternatively, the operating temperature.

[0028] exist Figure 1 In one example, a forced crankcase ventilation (PCV) system 16 is coupled to the engine intake, allowing gases in the crankcase to be discharged from the crankcase in a controlled manner. During non-pressurized conditions (when the manifold pressure (MAP) is less than atmospheric pressure (BP), the crankcase ventilation system 16 draws air into the crankcase 28 via a breather or crankcase ventilation duct 74. A first side 101 of the crankcase ventilation duct 74 may be mechanically coupled upstream of the compressor 50 or connected to the fresh air intake duct 13. In some examples, the first side 101 of the crankcase ventilation duct 74 may be coupled downstream of the air filter 54 to the intake duct 13 (as shown). In other examples, the crankcase ventilation duct may be coupled upstream of the air filter 54 to the intake duct 13. A second opposing side 102 of the crankcase ventilation duct 74 may be mechanically coupled or connected to the crankcase 28 via an oil separator 81.

[0029] The crankcase ventilation duct 74 also includes a sensor 77 coupled thereto, which provides estimates (e.g., flow rate, pressure, etc.) of the air flowing through the crankcase ventilation duct 74. In some embodiments, the crankcase ventilation duct sensor 77 may be a pressure sensor, referred herein as a crankcase pressure sensor (CKCP sensor) 77. When configured as a pressure sensor, the CKCP sensor 77 may be an absolute pressure sensor or an instrument sensor. In an alternative embodiment, the sensor 77 may be a flow sensor or a flow meter. In another embodiment, the sensor 77 may be configured as a venturi. In some embodiments, in addition to the pressure sensor or flow sensor 77, the crankcase ventilation duct may optionally include a venturi 75 for sensing the flow rate therethrough. In other embodiments, the pressure sensor 77 may be coupled to the neck of the venturi 75 to estimate the pressure drop across the venturi. One or more additional pressure sensors and / or flow sensors may be coupled to the crankcase ventilation system at alternative locations. For example, an atmospheric pressure sensor (BP sensor) 57 can be coupled upstream of the air filter 54 to the intake duct 13 to provide an estimate of atmospheric pressure. In one example, the BP sensor 57 can be used in conjunction with the gauge pressure sensor 77 when the crankcase ventilation sensor 77 is configured as an instrument sensor. In some embodiments, a pressure sensor 61 can be coupled downstream of the air filter 54 and upstream of the compressor 50 in the intake duct 13 to provide an estimate of the compressor inlet pressure (CIP). However, because the crankcase ventilation pressure sensor 77 can provide an accurate estimate of the compressor inlet pressure during periods of increased engine airflow conditions, such as during engine acceleration, the need for a dedicated CIP sensor may be reduced. Furthermore, a pressure sensor 59 can be coupled downstream of the compressor 50 to provide an estimate of the throttle inlet pressure (TIP). Any of the pressure sensors mentioned above can be an absolute pressure sensor or an instrument sensor.

[0030] The PCV system 16 also expels gases from the crankcase and into the intake manifold 44 via a conduit 76 (also referred to herein as PCV line 76). In some instances, PCV line 76 may include a PCV valve 78, which may be an electronically controlled valve controlled by controller 12. In another instance, PCV valve 78 may include a passively actuated mechanical valve. For example, the PCV valve may actively or passively change its flow constraints in response to a pressure drop thereon (or the flow rate through it). Thus, in one instance, PCV valve 78 may be an electronically controlled valve, wherein controller 12 may command a signal to change the valve's position from a fully open position (or a high-flow position) to a fully closed position (or a no-flow position) or vice versa, or any position in between. In another instance, PCV valve 78 may be passively actuated, as follows: Figures 3A to 3C The place is being discussed.

[0031] The gas in crankcase 28 (referred to herein as blow-by gas) may consist of unburned or unexhausted fuel, unburned fuel vapor, unburned air, and fully or partially burned gases. Additionally, oil mist or vapor may be present. Therefore, various oil-gas separators may be incorporated into the crankcase ventilation system 16 to reduce oil mist exiting the crankcase via the PCV system. For example, PCV line 76 may include a one-way oil-gas separator 80 that filters oil-gas from vapor leaving crankcase 28 before it re-enters intake manifold 44. Another oil-gas separator 81 may be located in crankcase ventilation duct 74 to remove oil-gas from the gas stream leaving the crankcase during boost operation. Additionally, PCV line 76 may include a vacuum sensor 82 coupled to the PCV system. In other embodiments, a MAP or manifold vacuum (ManVac) sensor may be located in intake manifold 44.

[0032] Engine system 10 is connected to fuel system 18. Fuel system 18 includes fuel tank 20 connected to fuel pump 21 and fuel vapor filter canister 90. During a refueling event, fuel can be pumped from an external source into the vehicle through refueling port 25. Fuel tank 20 can hold various fuel blends, including fuels with a range of alcohol concentrations, such as various gasoline-ethanol blends, including E10, E85, gasoline, and combinations thereof. Fuel level sensor 22 located in fuel tank 20 can provide an indication of fuel level (“fuel level input”) to controller 12. As depicted, fuel level sensor 22 may include a float connected to a variable resistor. Alternatively, other types of fuel level sensors may be used.

[0033] Fuel pump 21 is configured to pressurize fuel delivered to injectors (such as exemplary injector 45) of engine 10. It should be understood that fuel system 18 can be a non-return fuel system, a return fuel system, or various other types of fuel systems. Vapor generated in fuel tank 20 can be directed via conduit 93 to fuel vapor storage filter canister 90 (also referred to herein as fuel vapor filter canister, or simply filter canister), and then drawn into engine draw-out manifold 44.

[0034] A fuel vapor filter canister 90 (also referred to herein as a fuel vapor storage filter canister, or simply a filter canister) may be positioned within the evaporative emission system 19. The fuel vapor filter canister 90 is filled with a suitable adsorbent for temporarily capturing fuel vapors (including vaporized hydrocarbons) generated during fuel tank refueling operations. In one example, activated carbon is used as the adsorbent. When extraction conditions are met, such as when the filter canister is saturated, the vapors stored in the fuel vapor filter canister 90 can be extracted to the engine intake manifold 13 by opening the filter canister extraction valve (CPV) 92. Although a single filter canister 90 is shown, it should be understood that the evaporative emission system 19 may include any number of filter canisters. In one example, the CPV 92 may be a solenoid valve, wherein the opening or closing of the valve is actuated via the filter canister extraction valve solenoid.

[0035] A hydrocarbon sensor 67 can be positioned within the extraction line 91. By incorporating the hydrocarbon sensor 67, extraction from the canister 90 can be optimized while maintaining the stoichiometric air-fuel ratio for engine combustion. More specifically, the hydrocarbon sensor 67 can enable feedforward air-fuel ratio control for engine combustion during extraction from the fuel vapor storage canister. For example, based on an indication of the concentration of hydrocarbons extracted from the canister, the engine refueling strategy can compensate for fuel injection pulses to maintain the stoichiometric air-fuel ratio, which can prevent the risks of engine stall, lag, etc., from an air-fuel-rich mixture.

[0036] The hydrocarbon sensor 67 may include an adsorption-sensitive resistor that operates according to the adsorption principle based on Vander Walls' "a" constant, wherein the resistance of the hydrocarbon sensor 67 varies with the concentration of fuel vapor present. As discussed herein, the output of the hydrocarbon sensor may vary with the resistance of the hydrocarbon sensor. For example, the output regarding a particular resistance may include a specific fuel vapor concentration sensed via the hydrocarbon sensor.

[0037] Canister 90 may include a buffer (or buffer zone) (not shown), and each of the canister and the buffer includes an adsorbent. The volume of the buffer may be smaller than the volume of canister 90 (e.g., a portion thereof). The adsorbent in the buffer may be the same as or different from the adsorbent in the canister (e.g., both may include char). The buffer may be positioned within canister 90 such that during canister loading, fuel tank vapor is first adsorbed within the buffer, and then additional fuel tank vapor is adsorbed into the canister when the buffer is saturated. In contrast, during canister extraction, fuel vapor is first desorbed from the canister (e.g., reaching a threshold amount) and then desorbed from the buffer. In other words, the loading and unloading of the buffer is not synchronized with the loading and unloading of the canister. Therefore, the function of the canister buffer is to suppress any fuel vapor surges flowing from the fuel tank to the canister, thereby reducing the likelihood of any fuel vapor surges reaching the engine.

[0038] The filter canister 90 includes a vent line 86 for guiding gas from the filter canister 90 into the atmosphere when storing or trapping fuel vapor from the fuel tank 20. The vent line 86 can also allow fresh air to be drawn into the fuel vapor filter canister 90 when the stored fuel vapor is drawn into the engine intake duct 13 via extraction line 91 and CPV 92. While this example shows a vent 86 communicating with fresh, unheated air, various modifications are possible. The vent 86 may include a filter canister vent valve (CVV) 87 to regulate the air and vapor flow between the filter canister 90 and the atmosphere. The filter canister vent valve can also be used in diagnostic procedures. When a vent valve is included, it can be opened during fuel vapor storage operations (e.g., during fuel tank refueling) to allow air stripped of fuel vapor after passing through the filter canister to be pushed into the atmosphere. Similarly, during extraction operations (e.g., during filter canister regeneration and while the engine is running), the vent valve can be opened to allow a fresh airflow to strip fuel vapor stored in the filter canister. In one example, the filter canister vent valve 87 may be a solenoid valve, wherein the actuation of the valve via the filter canister vent solenoid actuates the opening or closing of the valve. Specifically, the filter canister vent valve may be a default-open valve that closes upon actuation of the filter canister vent solenoid. In some examples, an air filter (not shown) may be connected to a vent 86 between the filter canister vent valve 87 and the atmosphere.

[0039] The hybrid vehicle system 6 can have reduced engine operating time because the vehicle is powered by the engine system 10 during certain conditions and by the energy storage device during other conditions. While reduced engine operating time reduces total carbon emissions from the vehicle, it can also lead to insufficient extraction of fuel vapor from the vehicle's emission control system. To address this, a fuel tank isolation valve 85 can be included in the conduit 93, such that the fuel tank 20 is connected to the filter canister 90 via the valve. During normal engine operation, the isolation valve 85 can remain closed to limit the amount of daytime vapor or "running loss" vapor diverted from the fuel tank 20 to the filter canister 90. During refueling operations and selected extraction conditions, the isolation valve 85 can be temporarily opened, for example for a certain duration, to divert fuel vapor from the fuel tank 20 to the filter canister 90. Although the depicted example shows an isolation valve 85 positioned along the conduit 93, in alternative embodiments, the isolation valve can be mounted on the fuel tank 20. When the isolation valve 85 is closed, the fuel system can be considered sealed.

[0040] One or more pressure sensors 23 may be coupled to the fuel system 18 to provide an estimate of the fuel system pressure. In one example, the fuel system pressure is the fuel tank pressure, where the pressure sensor 23 is a fuel tank pressure sensor coupled to the fuel tank 20 to estimate the fuel tank pressure or vacuum level. While the depicted example shows a pressure sensor 23 directly coupled to the fuel tank 20, in alternative embodiments, the pressure sensor may be coupled between the fuel tank and the filter canister 90, specifically between the fuel tank and the isolation valve 85.

[0041] One or more temperature sensors 24 may also be coupled to the fuel system 18 to provide an estimate of the fuel system temperature. In one example, the fuel system temperature is the fuel tank temperature, where the temperature sensor 24 is a fuel tank temperature sensor coupled to the fuel tank 20 to estimate the fuel tank temperature. While the depicted example shows a temperature sensor 24 directly coupled to the fuel tank 20, in alternative embodiments, the temperature sensor may be coupled between the fuel tank and the FTIV 85. A canister temperature sensor 97 may be coupled to the canister 90 and configured to indicate temperature changes of the adsorbent material within the canister. Because fuel vapor adsorption is an exothermic reaction and fuel vapor desorption is an endothermic reaction, the canister temperature can be used to indicate the amount of fuel vapor adsorbed during a ventilation event (e.g., during refueling, and discussed further below; during diagnostics of the hydrocarbon sensor 67, which reasonably illustrates this), and / or the amount of fuel vapor desorbed during a pumping operation.

[0042] Fuel vapor released from the canister 90 during, for example, extraction operations can be directed via extraction line 91 into the engine intake manifold 44. The vapor flow along extraction line 91 can be regulated by a CPV 92 connecting the fuel vapor canister to the engine intake port. The amount and rate of vapor released by the CPV can be determined by the duty cycle of the associated canister extraction valve solenoid (not shown). Therefore, the duty cycle of the canister extraction valve solenoid can be determined by the vehicle's powertrain control module (PCM) (such as controller 12) in response to engine operating conditions, including, for example, engine speed-load conditions, air-fuel ratio, canister load, etc. As discussed above, in some instances, feedforward air-fuel ratio control during fuel vapor storage canister extraction can be utilized by the controller based on the concentration of fuel vapor directed to the engine intake manifold 44, where the fuel vapor concentration is measured via hydrocarbon sensor 67.

[0043] By commanding the filter canister extraction valve to close, the controller can seal the filter canister and evaporative emission system from the engine intake.

[0044] The fuel system 18 can be operated by the controller 12 in multiple modes by selectively adjusting various valves and solenoids. For example, the fuel system can be operated in a fuel vapor storage mode (e.g., during fuel tank refueling operations and when the engine is not running), in which the controller 12 can open the isolation valve 85 and CVV 87 while closing the CPV 92 to direct the fuel vapor during refueling into the canister filter 90, while preventing the fuel vapor from being directed into the intake manifold.

[0045] To give another example, the fuel system can operate in a refueling mode (e.g., when the vehicle driver requests refueling), where controller 12 can open isolation valve 85 and CVV 87 while maintaining CPV 92 closed to depressurize the fuel tank before allowing fuel to be added. Therefore, isolation valve 85 can remain open during the refueling operation to allow vapors to accumulate in the canister during refueling. After refueling is complete, the isolation valve can close.

[0046] As discussed, the fuel system can operate in a canister extraction mode (e.g., after the emission control ignition temperature has been reached and the engine is running), where controller 12 can open canister extraction valve 92 and canister vent valve while simultaneously closing isolation valve 85. Herein, a vacuum generated by the intake manifold of the operating engine can be used to draw fresh air through vent 86 and through fuel vapor canister 90 to extract stored fuel vapor into intake manifold 44. In this mode, the fuel vapor extracted from the canister is burned in the engine. Extraction can continue until the amount of fuel vapor stored in the canister is below a threshold. During extraction, the known vapor quantity / concentration can be used to determine the amount of fuel vapor stored in the canister, and then, later in the extraction operation (when the canister is fully extracted or emptied), the known vapor quantity / concentration can be used to estimate the loading status of the fuel vapor canister. In one example, this vapor quantity / concentration can be known via the output of hydrocarbon sensor 67. In addition, in some instances, the IAO2 sensor 43a can be used to determine the amount / concentration of vapor.

[0047] Figure 1 The controller 12 shown is a microcomputer, including a microprocessor unit 108, an input / output port 110, an electronic storage medium for executable programs and calibration values ​​(shown in this particular instance as a read-only memory chip 112), a random access memory 114, a keep-alive memory 116, and a data bus. The controller 12 can receive various signals from sensors 117 connected to the engine 10, including: measurements of intake mass airflow (MAF) from the mass airflow sensor 58; engine coolant temperature (ECT) from the temperature sensor 46; PCV pressure from the vacuum sensor 82; exhaust air-fuel ratio from the exhaust sensor 64; exhaust temperature sensor 65; crankcase ventilation manifold pressure sensor 77; BP sensor 57; CIP sensor 61; TIP sensor 59; filter canister temperature sensor 97; hydrocarbon sensor 67, etc. Furthermore, the controller 12 can monitor and adjust the positions of various actuators 118 based on inputs received from the various sensors. These actuators may include, for example, a throttle valve 42, an intake valve system 40, and an exhaust valve system 41, as well as PCV valves 78, CPV valves 92, FTIV valves 85, CVV valves 87, etc. The storage medium, read-only memory 112, can be programmed with computer-readable data representing instructions executable by processor 108 to perform the methods described below, as well as other contemplated but not specifically listed variations.

[0048] The controller 12 can also be configured to intermittently perform unwanted evaporative emission detection procedures on the fuel system 18 and / or the evaporative emission system 19. The tests can be performed by an evaporative level check module (ELCM) 99 communicatively coupled to the controller 12. The ELCM 99 can be coupled to a vent 86 located between the filter canister 90 and the atmosphere. The ELCM 99 may include a vacuum pump for applying negative pressure to the fuel system and / or the evaporative emission system during test execution. In some embodiments, the vacuum pump may be configured to be reversible. In other words, the vacuum pump may be configured to apply negative or positive pressure to the fuel system and / or the evaporative emission system. The ELCM 99 may also include a standard orifice and a pressure sensor 98. The standard orifice allows for the determination of a threshold pressure based on current environmental and operating conditions. Furthermore, although not explicitly shown, the ELCM 99 may include a switching valve that, when actuated via the controller to a first position, connects the ELCM to the atmosphere, and when actuated to a second position, seals the ELCM from the atmosphere. Therefore, in some instances that include an ELCM, a CVV may or may not be included additionally. After applying a vacuum to the fuel system and / or evaporative emission system, pressure changes (e.g., absolute changes or rate of change) at pressure sensor 98 can be monitored and compared to a threshold pressure. Based on this comparison, the presence of unwanted evaporative emissions in the fuel system and / or evaporative emission system can be diagnosed. Therefore, various diagnostic tests can be performed with the engine off (engine off test) or with the engine running (engine on test). Tests performed with the engine running may include applying negative pressure to the fuel system for a certain duration (e.g., until a target fuel tank vacuum is reached), and then sealing the fuel system while monitoring changes in fuel tank pressure (e.g., rate of change of vacuum level or final pressure value). Tests performed without the engine running may include sealing the fuel system after the engine is off and monitoring changes in fuel tank pressure. This type of test is referred to herein as the Engine Off Natural Vacuum Test (EONV). When the fuel system is sealed after the engine is off, a vacuum can form in the fuel tank because the fuel tank cools and fuel vapor condenses into liquid fuel. The amount of vacuum and / or the rate of vacuum formation can be compared to expected values. In another instance, during a vehicle shutdown event, the fuel tank pressure initially rises because heat continues to be released from the engine into the fuel tank. Pressure exceeding a threshold during relatively high ambient temperature conditions can be considered a pass test.

[0049] As discussed, the hybrid vehicle system 6 may include multiple torque sources available for one or more wheels 171; however, in other instances, the vehicle may include an engine with no other available torque sources. In the illustrated example, the hybrid vehicle system 6 includes an electric motor 152. The electric motor 152 may be a motor or a motor / generator. When one or more clutches 172 are engaged, the crankshaft 30 of the engine 10 and the electric motor 152 are connected to the wheels 171 via a transmission 154. In the depicted example, a first clutch is provided between the crankshaft 30 and the electric motor 152, and a second clutch is provided between the electric motor 152 and the transmission 154. The controller 12 may send signals to the actuator of each clutch 172 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft from the electric motor 152 and its connected components, and / or connecting or disconnecting the electric motor 152 from the transmission 154 and its connected components. The transmission 154 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

[0050] Motor 152 receives power from traction battery 158 (also described herein as an on-board energy storage device, energy storage unit, or battery) to provide torque to wheel 171. Motor 152 can also operate as a generator to provide power, for example, during braking operations, to charge traction battery 158.

[0051] The on-board energy storage device 158 can periodically receive electrical energy from a power source 191 located outside the vehicle (e.g., not part of the vehicle), as indicated by arrow 192. As a non-limiting example, the hybrid vehicle system 6 can be configured as a PHEV, whereby electrical energy can be supplied from the power source 191 to the energy storage device 158 via an electrical transmission cable 193. During the operation of recharging the energy storage device 158 from the power source 191, the electrical transmission cable 193 can electrically connect the energy storage device 158 and the power source 191. When the vehicle propulsion system is operated to propel the vehicle, the electrical transmission cable 193 can disconnect between the power source 191 and the energy storage device 158. The controller 12 can identify and / or control the amount of electrical energy stored at the energy storage device, which may be referred to as the state of charge (SOC).

[0052] In other instances, the electrical transmission cable 193 may be omitted, allowing electrical energy to be wirelessly received from the power source 191 at the energy storage device 158. For example, the energy storage device 158 may receive electrical energy from the power source 191 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Therefore, it should be understood that any suitable means may be used to recharge the energy storage device 158 from a power source that is not part of the vehicle.

[0053] The hybrid vehicle system 6 may include an exhaust gas recirculation (EGR) system. Specifically, the EGR system may include one or more of high-pressure EGR or low-pressure EGR. Figure 1 The exemplary illustration depicts a low-pressure EGR system. Specifically, EGR passages, including passages 162a and 162b, are indicated. It will be understood that passages 162a and 162b may include the same EGR passage, but are indicated as disconnected passages for clarity. The EGR passages including passages 162a and 162b may also include an EGR valve 164. By controlling the timing of the opening and closing of the EGR valve 164, the amount of exhaust gas recirculation can be appropriately adjusted.

[0054] Although Figure 1 Exemplary illustrations include ELCMs, but it is recognized herein that using such ELCMs could increase costs during manufacturing, which is likely to be avoided. Therefore, [the text then shifts to a different topic]... Figure 2The diagram 200 shows a partial depiction of a hybrid vehicle system 6. This vehicle system may include a vacuum pump 201 disposed in a vacuum pump conduit 202. The vacuum pump may include a rotary vane pump, diaphragm pump, liquid ring pump, piston pump, scroll pump, screw pump, Wankel pump, etc., and may be understood to be connected in parallel with the CVV 87. The vacuum pump conduit 202 may be configured to guide fluid flow (e.g., air and fuel vapor) from the ventilation line 86 around the filter canister vent valve 87. The vacuum pump conduit 202 may include a first check valve (CV1) 204 and a second check valve (CV2) 205. When the vacuum pump 201 is activated, air may be drawn from the ventilation line 86 between the filter canister 90 and the CVV 87, pass through the vacuum pump conduit 202 at the location between the filter canister vent valve 87 and the atmosphere, and return to the ventilation line 86. In other words, the vacuum pump can be activated to evacuate the fuel system, provided that the FTIV 85 is opened via a controller command. CV1 204 may include a pressure / vacuum actuated valve that can open in response to activation of the vacuum pump to evacuate the fuel system and can close in response to vacuum pump 201 being deactivated or shut down. Similarly, CV2 may include a pressure / vacuum actuated valve. When vacuum pump 201 is activated to evacuate the fuel system, CV2 205 may open to allow fluid flow to be directed from vacuum pump conduit 202 to the atmosphere and can close in response to vacuum pump 201 being shut down. It is understood that CVV 87 may be commanded to close in order to evacuate the fuel system (and / or evaporative exhaust system) via vacuum pump 201. Similarly, as will be discussed in detail below, in an instance where diagnostic procedures have been performed to reasonably illustrate hydrocarbon sensor 67, vacuum pump 201 may be used to draw a vacuum (e.g., a negative pressure relative to atmospheric pressure) on the intake manifold. In doing so, the CPV can be commanded to open, the CVV can be commanded to close, the FTIV can be commanded to close, and the vacuum pump 201 can be commanded to open to evacuate the intake manifold, as will be... Figure 4 It was discussed in detail.

[0055] As discussed above, an ELCM may include a standard orifice that allows for the determination of a vacuum level, indicating the absence of unwanted evaporative emissions if this vacuum level is achieved during evacuation of the fuel system and / or evaporative emission system. However, in Figure 2 In the depicted example, without an ELCM but including a vacuum pump 201, a standard orifice may not be present. Therefore, additional calibration can be used to determine a vacuum threshold to indicate the presence of unwanted evaporative emissions. For example, a 3D lookup table stored at the controller could be used to determine the threshold based on ambient temperature and fuel level. In this way, a standard orifice can be omitted, which reduces the costs associated with including an ELCM.

[0056] Furthermore, as discussed, ELCMs may include pressure sensors. Figure 2 The depicted example includes a pressure sensor 210 positioned within conduit 93. Therefore, it can be understood that FTIV 85 can be defined by a fuel tank pressure sensor (e.g., 23) (fuel tank pressure transducer) and pressure sensor 210 positioned within conduit 93 between FTIV 85 and canister 90. In this way, with FTIV 85 closed, pressure sensor 210 can monitor the pressure in the evaporative emission system (e.g., 19), and pressure sensor 23 can monitor the pressure in the fuel system (e.g., 18).

[0057] Therefore, by employing a vacuum pump 201 together with a pressure sensor 210 in the vacuum pump conduit 202 including CV1 204 and CV2 205, the manufacturing costs associated with devices including those for evacuating the fuel system and evaporative emission system (and for evacuating the intake manifold to perform diagnostics on a hydrocarbon sensor located between the filter canister and the CPV) during engine-off conditions can be reduced.

[0058] As discussed, CVV 87 can function to regulate the air and vapor flow between the filter canister 90 and the atmosphere, and can be controlled during or before diagnostic procedures. For example, the CVV can be opened during fuel vapor storage operations (e.g., during refueling), allowing air stripped of fuel vapor after passing through the filter canister to be pushed to the atmosphere. Similarly, during extraction operations (e.g., during filter canister regeneration and when the engine is running), the CVV can be opened to allow a flow of fresh air to strip fuel vapor stored in the filter canister. In exemplary figure 200, the configuration of the vacuum pump 201 positioned in the vacuum pump conduit 202 allows extraction and refueling operations to be performed without undesirable additional restrictions (pump 201 and check valves CV1 204, CV2 205). In other words, during extraction and refueling operations, the CVV can be commanded to open, where fluid flow through the vacuum pump conduit 202 can be prevented via check valves (CV1, CV2) and if the vacuum pump 201 is deactivated.

[0059] As discussed, engine manifold vacuum can be used to extract the filter canister. However, in some instances, sufficient intake manifold vacuum may not be available for effective filter canister extraction. For example, vacuum is a pumping loss, and the engine system can be configured to reduce this vacuum. Therefore, in some instances, extraction pump 230 may be positioned between filter canister extraction valve 92 and filter canister 90 to extract the filter canister under conditions of low intake manifold vacuum. When activated, for example by sending a signal to the actuator of the extraction pump via a controller, extraction pump 230 can evacuate the filter canister to draw fuel vapor from the canister and direct it to the engine intake for combustion. With the extraction pump activated, it is understood that the CVV can be commanded to open to extract the filter canister.

[0060] As mentioned above, feedforward air-fuel ratio control of engine combustion during extraction (via a hydrocarbon sensor connected to the extraction line between the canister and the intake manifold) allows for the determination of the concentration of fuel vapor introduced into the engine during extraction, enabling control of fuel injector pulses to manage the engine air-fuel ratio and prevent potential engine stall or lag. Therefore, it may be desirable to ensure that the hydrocarbon sensor (e.g., 67) positioned between the canister (e.g., 90) and the CPV (e.g., 92) functions as desired; otherwise, any compensation strategy may fail to properly adjust the fuel injection pulses to maintain the stoichiometric air-fuel ratio. An example of reasonably illustrating extraction control of the hydrocarbon sensor could include simply indicating whether the hydrocarbon sensor responds to an output level greater than a threshold output level during extraction, where the canister is known to contain stored fuel vapor, and the output level / threshold output level corresponds to the resistance of the hydrocarbon sensor varying with the concentration of fuel vapor present. However, for PHEVs that can operate in pure electric mode, the canister can remain clean for an extended period after the extraction event, provided the vehicle is operating in pure electric mode. More specifically, a refueling event can introduce fuel vapor into the filter canister, and the engine control strategy can subsequently request an extraction event to clean the canister. In doing so, the hydrocarbon sensor can be reasonably identified. However, after extraction, the vehicle can operate in pure electric mode for many days, with the fuel tank sealed off from the evaporative emission system. Therefore, no fuel vapor may be introduced into the evaporative emission system for an extended period, and thus the hydrocarbon sensor may not be diagnosed during these time periods. If the hydrocarbon sensor deteriorates during this process, subsequent refueling operations after filter canister extraction may cause engine lag and / or stall because the controller incorrectly estimates the concentration of fuel vapor inferred to be directed to the engine.

[0061] Therefore, it is desirable to be able to reasonably explain the diagnosis of the hydrocarbon sensor under the condition that the filter canister is clean. Therefore, the following Figure 4 An exemplary method for performing hydrocarbon sensor diagnostics is discussed. In short, the diagnostics may include, under a key-off event with the fuel system sealed (e.g., FTIV closed), turning the engine in a forward direction (e.g., the same direction the engine rotates as when burning air and fuel) without fuel (and without spark), wherein the PCV valve is at least partially open and the throttle is open to direct blow-by gas from the crankcase to the intake manifold. Furthermore, the CPV can then be commanded to open, and a vacuum pump (e.g., 201 or 99) or, in other instances, a evacuation pump (e.g., 230) can be activated to draw a vacuum (a negative pressure relative to atmospheric pressure) into the intake manifold. This vacuum can then draw the blow-by gas through the hydrocarbon sensor to the filter canister. In this way, a level greater than a predetermined HC sensor threshold level (also referred to herein as the threshold output level or threshold output) greater than the level under conditions where the vacuum pump is activated can indicate that the hydrocarbon sensor is operating as expected. In some instances, the engine can continue to run without fuel while a vacuum is drawn into the intake manifold. In other instances, the engine can be stopped running without fuel after a predetermined engine running duration that coincides with the activation of the vacuum pump (or extraction pump). The predetermined engine running duration may include the duration for which blow-by gas has reached the intake manifold in sufficient quantity, meaning a hydrocarbon sensor response expected to result in a level greater than the predetermined HC sensor threshold level for expected HC sensor operation.

[0062] In one instance, this method may include the ability to electronically command the opening of a PCV valve (e.g., an ePCV valve) via a controller. In another instance, where the vehicle includes a passively actuated mechanical PCV valve (e.g., an mPCV valve), the method may be performed if the control of the PCV valve is a function of at least the intake manifold pressure. Therefore, the following will discuss... Figures 3A to 3C Describe the mechanical PCV valve.

[0063] Turn now Figures 3A to 3C Exemplary illustrations of various configurations of a passive PCV valve (e.g., 78) under various conditions are shown. More specifically, Figure 3A The configuration of PCV valve 300 (e.g., 78) during idling and high intake manifold vacuum conditions is shown. Figure 3B The configuration of PCV valve 300 (e.g., 78) during high-speed, low-intake manifold conditions is shown. Figure 3CThe configuration of the PCV valve 300 (e.g., 78) during positive pressure conditions relative to atmospheric pressure in the intake manifold is shown. It is understood that... Figures 3A to 3C The depicted PCV valve 300 may include the above-described... Figure 1 The PCV valve 78 depicted is the same PCV valve.

[0064] Although the valve description relates to vehicle operating conditions (e.g., idling, high speed), it is understandable that when the vehicle is in the ignition-off state, the passive PCV valve can control the pressure in the intake manifold to... Figures 3A to 3C The depicted level of indication is used to employ the indicated construction. The following will discuss... Figure 4 The methodology described discusses this control.

[0065] Turn Figure 3A The PCV valve 300 may include a PCV valve housing 305, a plunger 310, and a spring 311. Furthermore, the PCV valve 300 may include a first needle valve 312 and a second needle valve 313. In response to idle speed and high intake manifold vacuum conditions, the high intake manifold vacuum can draw the plunger 310 toward the intake manifold, causing the first needle valve 312 to set against the first valve seat 314. Therefore, under high intake manifold vacuum conditions, the PCV valve 300 employs a low-flow configuration. In other words, because the first needle valve 312 is set against the first valve seat 314, fluid flow from the crankcase is prevented.

[0066] Turn Figure 3B This illustrates the conditions under which the PCV valve 300 operates at high engine speed and low intake manifold vacuum. In response to these conditions, the spring 311 can push the first needle valve 312 away from the first valve seat 314, thus allowing more fluid flow. Consequently, the second needle valve 313 can remain in contact with the second valve seat 315, and therefore, the high engine speed, low intake manifold vacuum condition represents a condition where the fluid flow through the PCV valve 300 is minimally constrained.

[0067] While the conditions for minimum constrained fluid flow described above pertain to high engine speeds, it is understood that in some instances, engine speeds may not necessarily be high, such as under ignition-off conditions where the throttle (e.g., 42) is commanded to open (e.g., fully open), as will be discussed in further detail below. In other words, the pressure in the intake manifold can be manipulated by controlling the throttle to the open position, which can therefore affect the configuration of the PCV valve (e.g., the minimum constrained configuration under low manifold vacuum conditions).

[0068] Turn Figure 3CThis illustrates the condition under which the PCV valve 300 is under positive pressure in the intake manifold. Under this condition, the PCV valve 300 can close. More specifically, the positive pressure in the intake manifold may cause the second needle valve 313 to sit against the second valve seat 315, thereby preventing fluid flow from the intake manifold to the crankcase.

[0069] Therefore, the PCV valve can occupy different configurations depending on the intake manifold pressure. Thus, by actively controlling the pressure in the intake manifold, the PCV can be controlled to a minimally constrained or open position. This control can be useful for diagnostic procedures that involve directing fluid flow, including blow-by gas, from the crankcase to the intake manifold to reasonably characterize hydrocarbon sensors (e.g., 67), as will be discussed in detail below.

[0070] Therefore, the above is related to Figures 1 to 3CThe described system enables a system for hybrid electric vehicles, comprising an engine including an intake port, an intake manifold, and an exhaust system. This system may also include a throttle valve positioned in the intake port. The system may further include a crankcase ventilation system including a crankcase ventilation valve positioned in a crankcase ventilation line to selectively fluidly connect the engine's crankcase to the intake manifold. The system may also include a motor and an evaporative exhaust system including a fuel vapor storage filter canister selectively fluidly connected to the atmosphere via a filter canister vent valve positioned in the ventilation line. The system may also include a vacuum pump positioned in a vacuum pump conduit parallel to the ventilation line. The system may further include a first check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line downstream of the filter canister vent valve. The system may also include a second check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line upstream of the filter canister vent valve. This system may also include a filter canister extraction valve located in the extraction line, the filter canister extraction valve selectively fluidly connecting the intake manifold to the fuel vapor storage filter canister. This system may also include a hydrocarbon sensor located in the extraction line between the fuel vapor storage filter canister and the filter canister extraction valve. This system may also include a controller that stores instructions in a non-transitory memory that, when executed, cause the controller to perform a sequence of steps in the event of a key-off event where the fuel vapor storage filter canister load is below a threshold canister load, and in driving cycles preceding the key-off event that include engine operation. The throttle valve may be commanded to open, and the filter canister vent may be commanded to close. The motor may be operated to rotate the engine without fuel to direct blow-by gases from the crankcase to the intake manifold via a crankcase ventilation valve in at least a partially open position. The vacuum pump can then be activated to draw out the blow-by gas through the hydrocarbon sensor via the filter canister extraction valve, which is commanded to the open position. Simultaneously, the hydrocarbon sensor can be indicated as to whether it has deteriorated if its output falls below a threshold output.

[0071] In one instance of such a system, the crankcase forced valve may be an electronically actuated crankcase forced valve, and the controller may store additional instructions to command the crankcase forced valve to the fully open position in order to direct blow-by gas in the crankcase to the intake manifold.

[0072] In another instance of such a system, the crankcase forced ventilation valve may be a passively actuated mechanical crankcase forced ventilation valve, and the controller may store additional instructions to manipulate the pressure in the intake manifold, thereby controlling the passively actuated mechanical crankcase forced ventilation valve to a minimum restraint position in order to direct blow-by gas in the crankcase to the intake manifold.

[0073] Turn now Figure 4 A high-level flowchart of an exemplary method 400 for performing extraction control hydrocarbon sensor diagnostics is shown. More specifically, method 400 can be utilized under the condition that the fuel vapor storage tank is clean and the key is off, and other conditions for performing such diagnostics are also met. Although reference will be made to the description herein and Figures 1 to 3C The system illustrated herein is used to describe method 400; however, it should be understood that similar methods can be applied to other systems without departing from the scope of this disclosure. Instructions for implementing method 400 and the remaining methods included herein can be provided by a controller (such as...). Figure 1 The controller 12) is based on instructions stored in non-transitory memory and combined with information from sensors in the engine system (such as temperature sensors, pressure sensors, and...). Figures 1 to 3C The controller may use signals received from other sensors described herein to perform actions. According to the method described herein, the controller may employ actuators such as motors / generators (e.g., 152), throttle valves (e.g., 42), fuel injectors (e.g., 45), PCV valves (e.g., 78), vacuum pumps (e.g., 99 or 201), CPVs (e.g., 92), etc.

[0074] Method 400 begins at 405 and may include an assessment of the current vehicle operating condition. The operating condition may be estimated, measured, and / or inferred, and may include one or more vehicle conditions (such as vehicle speed, battery state of charge, etc.), various engine conditions (such as engine status (on or off), engine load, engine temperature, engine speed, torque demand, exhaust air-fuel ratio, etc.), various fuel system conditions (such as fuel level, fuel type, fuel temperature, etc.), various evaporative emission system conditions (such as fuel vapor filter load, fuel tank pressure, etc.), and various environmental conditions (such as ambient temperature, humidity, atmospheric pressure, etc.).

[0075] Proceeding to 410, method 400 may include indicating whether a key-off event was detected. In other words, at 410, it may be indicated whether a key-off event occurred after a driving cycle. If not, method 400 may proceed to 415. At 415, method 400 may include maintaining the current vehicle operating condition, which may include: maintaining engine operation if the engine is being used to propel the vehicle, maintaining electric operation of the vehicle if the vehicle is being electrically propelled, or some combination of engine operation and electric operation if both are being used to propel the vehicle. Other operating conditions may also be maintained. Then, method 400 may terminate.

[0076] Returning to 410, in response to an indication of a key-off event, method 400 may proceed to 420. At 420, method 400 may include an indication of whether conditions reasonably described for the extraction control hydrocarbon sensor (e.g., 67) are met. In one example, met conditions may include an indication that the filter canister is clean (e.g., the filter canister load is below a filter canister load threshold, which includes, for example, less than 5% load). Met conditions may also include an indication that the temperature of the engine oil, as monitored via, for example, an oil temperature sensor (e.g., 51), is greater than a threshold temperature. Met conditions may additionally or alternatively include an indication that the heat dissipation index (HRI) for a previous driving cycle is greater than a threshold. The HRI may be based on the amount of heat dissipated by the engine during the previous driving cycle, the timing of heat dissipation, the length of time spent at different levels of driving aggression, environmental conditions, etc. Heat dissipated by the engine may be based on one or more of engine load, the amount of fuel injected over time and / or the intake manifold air mass over time, mileage, etc. For example, an HRI above a certain threshold could indicate that the crankcase may contain blow-by gas, which could be used to reasonably indicate a hydrocarbon sensor malfunction. For instance, if the vehicle was driven in pure electric mode before the ignition was turned off, the crankcase might not have enough blow-by gas to perform hydrocarbon sensor diagnostics.

[0077] In some instances, the condition satisfied at 410 may include an indication that a predetermined duration has elapsed since the last determination of whether the hydrocarbon sensor is operating as expected. In some instances, the condition satisfied may also include an indication that the PCV system has not deteriorated, an indication that the evaporative emission system has not deteriorated, etc.

[0078] If at 420 the conditions for performing hydrocarbon sensor diagnostics are not indicated, method 400 may proceed to 415 and may include maintaining the current vehicle conditions, which may additionally include putting the vehicle's controller to sleep in response to a key off event. Method 400 may then terminate.

[0079] Returning to 420, in response to indication that conditions for performing hydrocarbon sensor diagnostics have been met, method 400 may proceed to 425. At 425, method 400 may include maintaining the controller in an alert state so that diagnostics can be performed. Proceeding to 430, method 400 may include commanding the intake throttle to fully open. More specifically, the throttle may be electronically actuated to the fully open position via a command from the controller.

[0080] Proceeding to 435, method 400 may include rotating the engine without fuel via a motor (e.g., 152). More specifically, the controller may signal the motor to rotate the engine in the forward direction without providing fuel injection or sparks. The engine may rotate at a predetermined engine speed (e.g., a predetermined RPM, such as 500 RPM).

[0081] It's understandable that running the engine without fuel can create a vacuum in the intake manifold. However, with the throttle open, the vacuum force in the intake manifold is significantly reduced because the engine is running without fuel. This allows the engine to run without worrying about unwanted vacuum formation in the intake manifold.

[0082] Furthermore, in the case of a mechanical PCV valve, low intake manifold vacuum may cause the PCV valve to adopt a minimum constraint configuration. While turning the engine may cause positive pressure to be directed from the crankcase to the PCV valve (as discussed below, this could lead to crankcase blow-by being directed through the PCV valve and into the intake manifold), the positive pressure may not be sufficient to cause the PCV valve to adopt a minimum constraint configuration. Figure 3A The described closed configuration. In other words, when the PCV valve is mechanical, commanding the throttle to fully open can reduce the intake manifold vacuum to the point where the valve is at its minimum constraint. Figure 3B While turning the engine can direct blow-by gas to the PCV valve (resulting in positive pressure at the PCV valve), this directing of blow-by gas may not force the PCV valve to close. In some instances, engine speed can be controlled to ensure that the PCV valve is not forced to close due to the formation of positive pressure. For example, a pressure sensor (e.g., 66) can be positioned immediately adjacent to the PCV valve in the PCV system and can be used to monitor any pressure buildup at the PCV valve, allowing engine speed to be controlled to prevent the PCV valve from closing.

[0083] Therefore, when the PCV valve is mechanical, it is understandable that by commanding the throttle to open and controlling the speed at which the engine rotates without fuel, the PCV valve can be in a minimum constrained position, which may therefore lead to crankcase blow-by being directed to the intake manifold.

[0084] Alternatively, if the PCV valve is an electronic PCV valve, the controller can command the ePCV valve to open after the engine has been turned for a predetermined duration (e.g., a few seconds). More specifically, the controller can send a signal to the ePCV valve commanding it to be in the fully open position. With the ePCV valve commanded to be fully open, blow-by gas can be directed from the crankcase to the intake manifold.

[0085] Regardless of whether the PCV valve is mechanically or electronically controlled, method 400 can proceed to 440 and may include commanding the opening of the CPV and activating the vacuum pump (e.g., 201 or 99) to draw negative pressure relative to atmospheric pressure in the intake manifold. As discussed, in one instance, at 440, the engine can be deactivated, or in other words, stopped from running without fuel. However, in other instances, the engine can continue to run without fuel at 440. In the instances where the engine continues to run without fuel, it is understood that the engine speed can be controlled such that vapor is preferentially directed to the fuel vapor canister via activation of the vacuum pump (or, in some instances, an extraction pump). In other words, the engine speed can be controlled such that the vacuum suction force of the engine in the intake manifold is less than the vacuum suction force from the vacuum pump or extraction pump in the intake manifold. It is understood that by commanding the opening of the CPV and activating the vacuum pump, blow-by gases in the intake manifold can be directed through the hydrocarbon sensor to the fuel vapor canister, where they can be captured and stored.

[0086] In cases where the PCV valve includes a mechanical PCV valve, it is understood that evacuating the intake manifold via a vacuum pump may cause the PCV valve to close (see...). Figure 3A However, if sufficient blow-by gas already exists in the intake manifold due to running the engine without fuel, the gas in the intake manifold can be directed through the hydrocarbon sensor. This allows for a determination of whether the hydrocarbon sensor is functioning as expected, even if the evacuation closes the mechanical PCV valve. If actuating the vacuum pump to draw negative pressure in the intake manifold is anticipated to potentially close the mechanical PCV valve, then the engine can be commanded to stop running without fuel via the controller, while simultaneously activating the vacuum pump. However, in another instance, as discussed, the amount of negative pressure generated by the vacuum pump in the intake manifold can be monitored, and the vacuum pump can be controlled to maintain the negative pressure above a negative pressure threshold (closer to atmospheric pressure). This negative pressure threshold can include a vacuum level where, if the intake manifold pressure is higher (e.g., a smaller negative pressure, closer to atmospheric pressure), the PCV valve can be in a minimally constrained position. Figure 3BIf the intake manifold pressure is lower (e.g., a larger negative pressure, further away from atmospheric pressure), then the PCV valve can be in the closed position. Figure 3A Therefore, the vacuum pump can be controlled via a controller to maintain sufficient negative pressure in the intake manifold to guide blow-by gas through the hydrocarbon sensor to the fuel vapor filter, but the negative pressure is insufficient to close the mechanical PCV valve. In this case, blow-by gas can continue to be guided from the crankcase to the intake manifold via the PCV valve while the vacuum pump is activated. In this example, the engine can continue to run while the vacuum pump is operated.

[0087] Alternatively, when the PCV valve is electronically controlled, the ePCV can remain open when the vacuum pump is activated, and in one instance, the engine can be kept running without fuel, or in another instance, its running can be stopped without fuel.

[0088] Regardless of whether the strategy used is based on a mechanical or electrically controllable PCV valve, method 400 can proceed to 445. At 445, method 400 may include indicating whether the hydrocarbon sensor response or output is greater than a predetermined HC sensor threshold or threshold output. If not, method 400 may proceed to 450 and may include indicating whether a predetermined duration has elapsed since the vacuum pump was actuated. The predetermined duration at 450 may include a duration in which, if the hydrocarbon sensor operates as expected, the HC sensor response can be expected to be greater than a predetermined HC sensor threshold level. At 450, if the predetermined duration has not yet elapsed, method 400 may return to 445, where monitoring of the HC sensor response may continue.

[0089] Alternatively, at 450, in response to the elapsed of a predetermined duration, method 400 may proceed to 455. At 455, method 400 may include indicating degradation of the hydrocarbon sensor. Proceeding to 460, method 400 may include storing the test results at a controller. A malfunction indicator lamp (MIL) on the vehicle's dashboard may be illuminated to alert the vehicle driver to a request for engine repair, particularly of the hydrocarbon sensor. Furthermore, at 460, the vehicle's operating condition may be updated due to the indicated degradation.

[0090] Updating vehicle operating conditions in response to indicated degradation at 460 locations could include updating the canister extraction schedule so that the canister is extracted only under conditions unlikely to adversely affect engine operation. For example, following a refueling event, the vehicle controller could identify situations where canister extraction is not expected to cause adverse engine operation (e.g., stall or lag), and could initiate extraction under such conditions. One example could include a deceleration fuel cut-off (DFSO) event, where even fuel vapor of unknown concentration will be introduced into the engine during extraction, as the engine does not burn air and fuel and therefore does not produce adverse operation. In another example, canister extraction could be scheduled for a key-off event, where the exhaust catalyst is still hot (e.g., above ignition temperature), where extraction can be performed by running the engine without refueling and commanding the CPV and CVV to open, which directs fuel vapor stored in the canister to the hot exhaust catalyst.

[0091] At step 465, method 400 may include commanding the CPV to close, and if the vehicle includes an ePCV, the ePCV may be commanded to a fully closed position via the controller. Furthermore, at step 465, the vacuum pump may be deactivated, and the throttle may remain open.

[0092] At 470, method 400 may include drawing any gas from the intake manifold to the exhaust system, where the exhaust catalyst is expected to still be hot (e.g., above ignition temperature) since the driving cycle occurs just before the key-off event. Drawing gas to the exhaust system when the engine is running without fuel may include maintaining engine running without fuel. Alternatively, when the engine is off, drawing gas from the intake manifold to the exhaust system may include commanding the engine to run in the forward direction without fuel. After running the engine without fuel for a predetermined duration, the engine may be commanded to be deactivated or commanded to be shut off. Furthermore, after deactivating the engine at 470, the throttle may be returned to its previous position before performing HC sensor diagnostics.

[0093] At step 475, method 400 may include putting the controller to sleep. Then, method 400 may end.

[0094] Returning to 445, in response to the HC sensor response being greater than a predetermined HC sensor threshold, method 400 may proceed to 480. At 480, method 400 may include instructing the hydrocarbon sensor to operate as desired. Proceeding to 460, method 400 may include storing the result at the controller and updating the vehicle operating conditions to reflect the passed result. Updating the vehicle operating conditions in response to an indication that the hydrocarbon sensor has not deteriorated may include maintaining engine operating conditions, electric motor operating conditions, extraction schedules, etc., in their current operating state.

[0095] At step 465, method 400 may include commanding the CPV to close, and commanding the ePCV to close if the ePCV has been commanded to open. Additionally, at step 465, the vacuum pump may be deactivated.

[0096] Continuing to 470, method 400 may include drawing the intake manifold to the exhaust catalyst and returning the throttle to its position before performing the diagnostics described above, and then putting the controller to sleep at 475. Method 400 may then end.

[0097] Therefore, based on the above description, a method may include directing blow-by gas from the crankcase of a vehicle's engine to the engine's intake manifold, and then to a fuel vapor storage filter located in the vehicle's evaporative emission system; and indicating whether a hydrocarbon sensor for feedforward air-fuel ratio control during extraction from the fuel vapor storage filter operates as desired, based on the response of a hydrocarbon sensor during the directing process. Directing the blow-by gas may include a key-off condition after the engine is in operation (e.g., burning air and fuel) to propel the vehicle's driving cycle.

[0098] In examples of this method, directing blow-by gas to the intake manifold may include opening a crankcase forced valve located in a line connecting the crankcase to the intake manifold. As one example, the crankcase forced valve may include an electronically actuated valve, and the crankcase forced valve may be electrically actuated to a fully open position to direct blow-by gas to the intake manifold. However, in another example, the crankcase forced valve may include a passively mechanically actuated valve, and in this case, the crankcase forced valve may be controlled to a minimum restraint position to direct blow-by gas to the intake manifold.

[0099] This method may also include commanding the full opening of a throttle valve positioned in the engine's intake port, wherein the throttle valve is electronically actuated to guide blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

[0100] In one example of the method, directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter can also include actuating a vacuum pump positioned between the fuel vapor storage filter and the atmosphere to draw in negative pressure relative to atmospheric pressure in the intake manifold. In this example, the vacuum pump may be positioned in the vent line between the fuel vapor storage filter and the atmosphere. However, in another example, the vacuum pump may be positioned in a vacuum pump duct connected in parallel with the vent line, rather than in the vent line itself.

[0101] In this approach, indicating whether the hydrocarbon sensor is operating as expected may include indicating hydrocarbon sensor degradation in response to the hydrocarbon sensor output falling below a threshold output during the process of guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

[0102] Furthermore, in this method, directing blow-by gas from the intake manifold to the fuel vapor storage filter can include fluidly connecting the intake manifold to the fuel vapor storage filter, and can also include rotating the engine without fuel and without sparks.

[0103] Additionally, in this method, guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter can also include an indication that the load on the fuel vapor storage filter is below a threshold filter load.

[0104] Another example of the method may include performing diagnostics on a hydrocarbon sensor connected to a draw-off line between the engine's intake manifold and a fuel vapor storage filter located in the evaporative emission system of an engine-driven vehicle. This diagnostics can be performed by rotating the engine without fuel during a key-off event to direct blow-by gas from the engine's crankcase to the intake manifold, and then directing the blow-by gas through the draw-off line via the hydrocarbon sensor to the fuel vapor storage filter. In this way, hydrocarbon sensor degradation can be indicated in response to a hydrocarbon sensor response to blow-by gas being less than a threshold hydrocarbon sensor response during the direction of blow-by gas through the hydrocarbon sensor.

[0105] In this method, performing diagnostics may also include indicating that the fuel vapor storage tank loading status is below a threshold tank loading status.

[0106] In this method, directing blow-by gas from the crankcase to the intake manifold may include fluidly connecting the crankcase to the intake manifold.

[0107] In this method, guiding the blow-by gas through the hydrocarbon sensor via an extraction line may include activating a vacuum pump positioned between the fuel vapor storage tank and the atmosphere, or activating an extraction pump positioned between the fuel vapor storage tank and the intake manifold, to draw in negative pressure relative to atmospheric pressure in the intake manifold. Guiding the blow-by gas through the hydrocarbon sensor may also include fluidly connecting the intake manifold to the fuel vapor storage tank.

[0108] This method may also include controlling the pressure in the intake manifold while performing diagnostics, wherein controlling the pressure in the intake manifold includes controlling the position of the throttle valve located in the engine's intake port.

[0109] Turn now Figure 5 It shows the method for using according to Figure 4 An exemplary timeline 500 for performing hydrocarbon sensor diagnostics is provided. Exemplary timeline 500 includes curve 505 indicating whether a key-off condition has been indicated over time. Timeline 500 also includes curve 510 indicating whether conditions for performing hydrocarbon sensor diagnostics have been met over time. Timeline 500 also includes curve 515 indicating engine state over time. Over time, the engine may be off, rotating in the forward direction, or rotating in the reverse direction. Timeline 500 also includes curve 520 indicating the position of the intake throttle valve (e.g., 42) over time. Timeline 500 also includes curve 525 indicating the state of the CPV over time; and curve 530 indicating the state of the CVV over time. Timeline 500 also includes curve 535 indicating the output of the hydrocarbon sensor (e.g., 67) over time. The output can indicate a richer (e.g., larger) amount of vapor / gas detected by the hydrocarbon sensor, or a less rich or leaner amount of vapor / gas detected by the hydrocarbon sensor. Line 536 represents a predetermined HC sensor threshold or threshold output, wherein if the predetermined HC sensor threshold or threshold output is reached or exceeded during hydrocarbon sensor diagnostics, it indicates that the hydrocarbon sensor is not degraded, or in other words, is operating as expected. Timeline 500 also includes curve 540, indicating the fuel injection status of the engine cylinder over time. Timeline 500 also includes curve 545, indicating the status of the ePCV (e.g., 78) over time. Timeline 500 also includes curve 550, indicating the status of the vacuum pump (e.g., 201) over time. Timeline 500 also includes curve 555, indicating whether hydrocarbon sensor deterioration is indicated over time.

[0110] Understandably, for example, in Timeline 500, the vehicle system includes electronically actuated PCV valves or ePCV valves, rather than mechanical PCV valves. Furthermore, the vehicle system includes... Figure 2The vacuum pump described (e.g., 210), with Figure 1 The ELCM described is the opposite.

[0111] At time t0, the vehicle is in operation, with the engine rotating in the forward direction (curve 515) and fuel injection (curve 540) being supplied to the engine. Although not explicitly stated, it is understood that a spark is also supplied to the engine at time t0. Therefore, it is understood that the engine is burning air and fuel at time t0. Therefore, no key-off event is indicated (curve 505), no conditions for performing HC sensor diagnostics are indicated (curve 510), CPV is closed (curve 525), CVV is open (curve 530), ePCV valve is closed (curve 545), and vacuum pump is closed (curve 550). Because CPV is closed and the engine is in operation, no gas flow passes through the hydrocarbon sensor, and therefore lean output is indicated (curve 535). Throttle position (curve 520) is a function of driver demand and does not indicate hydrocarbon sensor degradation (curve 555).

[0112] Between times t0 and t1, the throttle valve becomes more closed, instructing the vehicle driver to release the accelerator pedal. At time t1, a key off event is indicated, and therefore, the engine is shut off or deactivated. Engine deactivation includes ceasing fuel injection and also includes ceasing spark supply. In response to the key off event, the controller can determine whether conditions for performing hydrocarbon sensor diagnostics are met, as discussed in detail above with respect to step 420 of method 400.

[0113] At time t2, the conditions for performing hydrocarbon sensor diagnostics are met (curve 510). Therefore, at time t3, the throttle is commanded to the fully open position via the controller. At time t4, the engine is activated via the motor (e.g., 152) to rotate in the forward direction without fuel. With the engine rotating without fuel, crankcase gases from the crankcase can be directed towards the ePCV valve and intake manifold (via the PCV line, e.g., 76). Therefore, at time t5, after a short duration (e.g., 1-2 seconds), the ePCV valve is commanded to open (curve 545). By commanding the ePCV valve to open, gases directed towards the intake manifold due to engine rotation can pass through the ePCV valve on their way to the intake manifold. Furthermore, at time t5, the CPV is commanded to open, thereby fluidly connecting the intake manifold to the hydrocarbon sensor and fuel vapor filter. Additionally, the CVV is commanded to close and the vacuum pump is commanded to operate. More specifically, the CVV is commanded to close, allowing the vacuum pump to draw negative pressure into the intake manifold by opening the CPV. In this example, the engine stops rotating without fuel at time t4.

[0114] With the vacuum pump actuated, ePCV valve open, CPV and throttle valve open, and CVV closed, it is understandable that the vacuum pump can draw blow-by gas that has been guided from the crankcase to the intake manifold through the hydrocarbon sensor to the fuel vapor filter.

[0115] Therefore, between time t5 and time t6, the output of the hydrocarbon sensor is monitored via the controller to indicate whether the response of the hydrocarbon sensor reaches or exceeds a predetermined HC sensor threshold represented by line 536. However, between time t5 and time t6, the output of the hydrocarbon sensor indicates a condition that is dilute than the predetermined HC sensor threshold. In other words, if the hydrocarbon sensor operates as expected, the HC sensor will not respond as expected between time t5 and time t6.

[0116] Therefore, at time t6, the hydrocarbon sensor is indicated to be deteriorating (curve 555). The result is stored at the controller, and in some instances, the MIL (Mortar Indicator Light) on the vehicle's dashboard can be illuminated, thus alerting the driver to a request for vehicle repair to address the deteriorated sensor.

[0117] At time t6, indicating hydrocarbon sensor degradation, the vacuum pump is deactivated, the ePCV valve is commanded to close, the CPV valve is commanded to close, and the CVV valve is commanded to open. The engine is activated to run without fuel to draw any gases from the intake manifold to the exhaust catalyst, which is above ignition temperature due to the driving cycle ending at the key-off event. Therefore, between time t6 and time t7, the controller maintains the engine running without fuel for a predetermined duration, which includes the amount of time during which any gases present in the intake manifold are expected to be diverted to the exhaust catalyst. In other instances, an intake oxygen sensor can be used to monitor the gas concentration in the intake manifold, where the engine can run without fuel until the gas concentration falls below a threshold concentration.

[0118] At time t7, since the test results have already been stored at the controller, the conditions for performing hydrocarbon sensor diagnostics are no longer indicated. Therefore, the controller commands the motor to stop the engine from rotating without fuel, and returns the throttle to its previous position before starting diagnostics. Although not explicitly stated, the controller can enter sleep mode immediately after time t7, after returning the throttle to its initial position and stopping the engine rotation. Between time t7 and time t8, the vehicle remains in the ignition off state.

[0119] While timeline 500 depicts an example of an electronically actuated PCV valve, as discussed in relation to method 400 above, in some instances, diagnostics can be performed even when the vehicle includes a mechanical PCV valve (mPCV valve). Therefore, steering... Figure 6 Another exemplary timeline 600 is shown, illustrating how hydrocarbon sensor diagnostics can be performed in this scenario. Timeline 600 and... Figure 5 The timelines depicted are identical, and therefore, for the sake of brevity, only the differences between timelines 500 and 600 will be emphasized. Specifically, the difference between timelines 500 and 600 is that, instead of the ePCV valve (curve 545), timeline 600 includes an mPCV valve. The mPCV valve can be positioned by... Figure 3A The first closed position can be in the position indicated by Figure 3B The second position indicates the opening or minimum constraint, or it can be in the position determined by... Figure 3C The third closed position is indicated by dashed lines 646 and 647, which separate the first position from the second position and the second position from the third position.

[0120] In short, between time t0 and time t1, the mPCV valve is in its first position, while the engine operates to burn air and fuel, indicating that the intake manifold vacuum is sufficiently large to close the mPCV valve, thus assuming its first configuration. Figure 3A At time t1, the engine stops, and therefore, the pressure in the intake manifold becomes such that the mPCV valve is in its second or minimum constraint position. If the conditions for performing diagnostics are met at time t2, the throttle is commanded to open at time t3, and at time t4, the engine is controlled via the motor to rotate in the forward direction without fuel. However, even with the engine rotating, the mPCV valve remains in the minimum constraint second position because, with the throttle open, there is insufficient vacuum in the intake manifold to cause the mPCV valve to adopt the first configuration, and additionally, the positive pressure directed to the mPCV valve by rotating the engine without fuel to guide blow-by from the crankcase to the intake manifold is insufficient to force the mPCV valve to adopt the first configuration. In this way, crankcase blow-by can be directed to the intake manifold via the mPCV valve in the second position.

[0121] At time t5, the vacuum pump is activated (and the CPV is opened and the CVV is closed), and although not explicitly shown, in some instances it can be controlled to draw a sufficient amount of vacuum in the intake manifold to direct blow-by gas to the filter canister, but in which case the mPCV valve is maintained in its minimum constraint second position. Furthermore, in this exemplary timeline, at time t5 the engine is stopped and rotated in the forward direction without fuel. Therefore, between time t5 and time t6, the mPCV valve remains in the second position, and the output of the hydrocarbon sensor is monitored. Between time t5 and time t6, the output of the hydrocarbon sensor reaches a predetermined HC sensor threshold (line 636), thus not indicating hydrocarbon sensor degradation (curve 655). The test results are stored at the controller.

[0122] Upon obtaining the test results, the vacuum pump is deactivated (curve 650), the CPV is closed (curve 625), and the CVV is opened (curve 630). Between time t6 and time t7, the engine is reactivated to run in the forward direction without fuel to direct any gases in the intake manifold to the exhaust catalyst. At time t7, the conditions for performing diagnostics are no longer met (curve 610), and therefore, the engine is stopped running without fuel (curve 615), and the throttle is returned to its initial position before diagnostics. Between time t7 and time t8, the vehicle is kept in the ignition off state.

[0123] In this way, the hydrocarbon sensor used for feedforward air-fuel ratio control during fuel vapor storage canister operation can be diagnosed, even under conditions where the filter canister is clean, to determine whether the hydrocarbon sensor is functioning as expected. Diagnosing the hydrocarbon sensor under these conditions reduces or avoids situations where a deteriorated hydrocarbon sensor could lead to engine lag or stall, air-fuel errors, and potential exhaust emissions. The ability to diagnose the hydrocarbon sensor under these clean filter canister conditions is particularly advantageous for hybrid vehicles with limited engine operating time and where the fuel tank is sealed except for refueling events and other diagnostics.

[0124] The technical advantage is that, under clean filter conditions, it may be advantageous to diagnose hydrocarbon sensors in a manner that does not release fuel vapors / oil vapors into the atmosphere. Therefore, the technical advantage is that, after a driving cycle utilizing the engine and with a clean filter, by running the engine without fuel with the PCV valve open, blow-by gas from the crankcase can be directed to the intake manifold, and this blow-by gas can be directed to the filter canifold via activation of a vacuum pump positioned between the filter canifold and the atmosphere. During the gas's direction to the filter canifold, the gas passes through the hydrocarbon sensor, thus rationally characterizing the sensor. In this way, the hydrocarbon sensor can be rationally characterized under conditions where undesirable emissions are not introduced into the atmosphere and the filter canifold is clean. Rational characterization of the hydrocarbon sensor under these conditions can improve engine operation and increase engine life. Consequently, customer satisfaction may be improved.

[0125] This article describes and references Figures 1 to 3C The system described herein and referenced Figure 4The method can implement one or more systems and one or more methods. In one example, a method includes directing blow-by gas from the crankcase of a vehicle's engine to the engine's intake manifold, and then to a fuel vapor storage filter located in the vehicle's evaporative emission system; and indicating, based on the response of a hydrocarbon sensor during the directing, whether a hydrocarbon sensor for feedforward air-fuel ratio control during extraction from the fuel vapor storage filter is operating as desired. In a first example of the method, the method may further include a key-off condition after the engine is in operation to propel the vehicle in a driving cycle. A second example of the method optionally includes the first example and further includes directing the blow-by gas to the intake manifold by opening a crankcase forced valve located in a line connecting the crankcase to the intake manifold. A third example of the method optionally includes any one or more of the first to second examples and further includes the crankcase forced valve being electronically actuated, and the crankcase forced valve being electronically actuated to a fully open position to direct the blow-by gas to the intake manifold. A fourth embodiment of the method optionally includes any one or more of the first to third embodiments, and further includes wherein the crankcase forced valve is passively mechanically actuated, and wherein the crankcase forced valve is controlled to a minimum restraint position to direct blow-by gas to the intake manifold. A fifth embodiment of the method optionally includes any one or more of the first to fourth embodiments, and further includes commanding a throttle valve positioned in the engine's intake port to fully open, wherein the throttle valve is electronically actuated to direct blow-by gas from the crankcase to the intake manifold, and then to the fuel vapor storage filter. A sixth embodiment of the method optionally includes any one or more of the first to fifth embodiments, and further includes wherein directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter also includes actuating a vacuum pump positioned between the fuel vapor storage filter and the atmosphere to draw negative pressure relative to atmospheric pressure in the intake manifold. A seventh embodiment of the method optionally includes any one or more of the first to sixth embodiments, and further includes wherein a vacuum pump is positioned in a vent line between the fuel vapor storage filter and the atmosphere. An eighth embodiment of the method optionally includes any one or more of the first to seventh embodiments, and further includes wherein the vacuum pump is positioned in a vacuum pump duct in parallel with the ventilation line, rather than in the ventilation line. A ninth embodiment of the method optionally includes any one or more of the first to eighth embodiments, and further includes wherein indicating whether the hydrocarbon sensor is operating as desired includes indicating hydrocarbon sensor degradation in response to the hydrocarbon sensor output falling below a threshold output during the process of directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.A tenth example of the method optionally includes any one or more of the first to ninth examples, and further includes guiding blow-by gas from the intake manifold to the fuel vapor storage filter can fluidly connecting the intake manifold to the fuel vapor storage filter can, and further includes rotating the engine without fuel and without sparks. An eleventh example of the method optionally includes any one or more of the first to tenth examples, and further includes guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter can also include an indication that the load on the fuel vapor storage filter can is below a threshold filter load.

[0126] Another example of the method includes: performing diagnostics on a hydrocarbon sensor coupled to an extraction line located between an intake manifold of the engine and a fuel vapor storage filter located in the evaporative emission system of an engine-driven vehicle; directing blow-by gas from the engine crankcase to the intake manifold by rotating the engine without fuel during a key-off event, and then directing the blow-by gas through the extraction line via the hydrocarbon sensor to the fuel vapor storage filter, wherein hydrocarbon sensor degradation is indicated in response to a hydrocarbon sensor response to the blow-by gas being less than a threshold hydrocarbon sensor response during the direction of the blow-by gas through the hydrocarbon sensor. In a first example of the method, the method further includes wherein performing diagnostics also includes an indication that the fuel vapor storage filter loading status is below a threshold filter loading status. A second example of the method optionally includes the first example and further includes wherein directing the blow-by gas from the crankcase to the intake manifold includes fluidly coupling the crankcase to the intake manifold. A third embodiment of the method optionally includes any one or more of the first to second embodiments, and further includes, wherein directing blow-by gas through a siphon line to a hydrocarbon sensor includes activating a vacuum pump positioned between a fuel vapor storage filter and the atmosphere, or activating a siphon pump positioned between a fuel vapor storage filter and an intake manifold, to draw negative pressure relative to atmospheric pressure in the intake manifold; and wherein directing blow-by gas through a hydrocarbon sensor also includes fluidly connecting the intake manifold to the fuel vapor storage filter. A fourth embodiment of the method optionally includes any one or more of the first to third embodiments, and further includes controlling pressure in the intake manifold while performing diagnostics, wherein controlling pressure in the intake manifold includes controlling the position of a throttle valve positioned in the engine's intake port.

[0127] A system for a hybrid electric vehicle includes: an engine including an intake port, an intake manifold, and an exhaust system; a throttle valve positioned in the intake port; a crankcase forced ventilation system including a crankcase forced ventilation valve positioned in a crankcase forced ventilation line for selectively fluidly connecting the engine's crankcase to the intake manifold; a motor; an evaporative emission system including a fuel vapor storage filter canister selectively fluidly connected to the atmosphere via a filter canister vent valve positioned in a ventilation line; a vacuum pump positioned in a vacuum pump conduit in parallel with the ventilation line; a first check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line downstream of the filter canister vent valve; a second check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line upstream of the filter canister vent valve; and a filter canister extraction valve positioned in an extraction line, the filter canister extraction valve connecting the intake manifold... A tubing is selectively fluidly connected to a fuel vapor storage filter canister; a hydrocarbon sensor is positioned in the extraction line between the fuel vapor storage filter canister and a filter canister extraction valve; and a controller stores instructions in a non-transitory memory that, when executed, cause the controller to: command the throttle to open and command the filter canister vent valve to close during a key-off event in which the filter canister load is below a threshold filter canister load, and during driving cycles preceding the key-off event including engine operation; operate the motor to rotate the engine without fuel, thereby directing blow-by gas from the crankcase to the intake manifold via a crankcase forced ventilation valve in at least a partially open position, and also operate a vacuum pump to draw the blow-by gas through the hydrocarbon sensor via the filter canister extraction valve commanded to the open position; and, while drawing the blow-by gas through the hydrocarbon sensor, indicate hydrocarbon sensor degradation in response to the hydrocarbon sensor output being below a threshold output. In a first embodiment of the system, the system further includes an electronically actuated crankcase forced ventilation valve, and a controller storing additional instructions to command the crankcase forced ventilation valve to a fully open position to direct blow-by gas from the crankcase to the intake manifold. A second embodiment of the system optionally includes the first embodiment and further includes a passively actuated mechanical crankcase forced ventilation valve, and a controller storing additional instructions to manipulate pressure in the intake manifold to control the passively actuated mechanical crankcase forced ventilation valve to a minimum restraint position to direct blow-by gas from the crankcase to the intake manifold.

[0128] It should be noted that the exemplary control and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored as executable instructions in non-transitory memory and can be implemented by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threaded processing strategies, etc. Therefore, the various actions, operations, and / or functions shown can be executed in the shown order, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the shown actions, operations, and / or functions can be repeatedly executed depending on the specific strategy used. Furthermore, the described actions, operations, and / or functions can be graphically represented as code to be programmed into a non-transitory memory of a computer-readable storage medium in an engine control system, wherein the described actions are implemented by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0129] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as numerous variations are possible. For example, the above-described techniques can be applied to V6, inline 4, inline 6, V12, opposed 4, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or properties.

[0130] The following claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may refer to an "a" element or a "first" element or its equivalents. These claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amendments to these claims or by filing new claims in this application or related applications. Such claims, whether broader, narrower, identical, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

[0131] According to the present invention, a method includes: directing blow-by gas from the crankcase of a vehicle's engine to the engine's intake manifold, and then to a fuel vapor storage filter located in the vehicle's evaporative emission system; and indicating, based on the response of a hydrocarbon sensor during the directing, whether a hydrocarbon sensor for feedforward air-fuel ratio control during extraction from the fuel vapor storage filter is operating as desired.

[0132] According to an embodiment, guiding blow-by includes a key-off condition after the engine is in operation to propel the vehicle in a driving cycle.

[0133] According to an embodiment, directing blow-by gas to the intake manifold includes opening a crankcase forced valve located in a line connecting the crankcase to the intake manifold.

[0134] According to an embodiment, the crankcase forced valve is electronically actuated, and wherein the crankcase forced valve is electronically actuated to a fully open position to direct blow-by gas into the intake manifold.

[0135] According to an embodiment, the crankcase forced valve is passively mechanically actuated, and wherein the crankcase forced valve is controlled to a minimum restraint position to direct blow-by gas to the intake manifold.

[0136] According to an embodiment, the invention is further characterized by commanding the full opening of a throttle valve positioned in the engine's intake port, wherein the throttle valve is electronically actuated to guide blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

[0137] According to an embodiment, guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter also includes actuating a vacuum pump positioned between the fuel vapor storage filter and the atmosphere to draw in negative pressure relative to atmospheric pressure on the intake manifold.

[0138] According to an embodiment, the vacuum pump is located in the ventilation duct between the fuel vapor storage filter and the atmosphere.

[0139] According to an embodiment, the vacuum pump is located in a vacuum pump duct that is connected in parallel with the ventilation duct, rather than in the ventilation duct itself.

[0140] According to an embodiment, indicating whether a hydrocarbon sensor is operating as expected includes indicating hydrocarbon sensor degradation in response to the hydrocarbon sensor output falling below a threshold output during the process of guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

[0141] According to an embodiment, directing blow-by gas from the intake manifold to the fuel vapor storage filter includes fluidly connecting the intake manifold to the fuel vapor storage filter, and also includes rotating the engine without fuel and without sparks.

[0142] According to an embodiment, guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter also includes an indication that the load on the fuel vapor storage filter is below a threshold filter load.

[0143] According to the present invention, a method includes: performing diagnostics on a hydrocarbon sensor coupled to an extraction line located between an intake manifold of an engine and a fuel vapor storage filter located in an evaporative emission system of an engine-driven vehicle; directing blow-by gas from the engine crankcase to the intake manifold by rotating the engine without fuel during a key-off event, and then directing the blow-by gas through the extraction line via the hydrocarbon sensor to the fuel vapor storage filter, wherein hydrocarbon sensor degradation is indicated in response to a hydrocarbon sensor response to the blow-by gas being less than a threshold hydrocarbon sensor response during the direction of the blow-by gas through the hydrocarbon sensor.

[0144] According to an embodiment, performing diagnostics also includes an indication that the loading status of the fuel vapor storage filter is below a threshold filter loading status.

[0145] According to an embodiment, directing blow-by gas from the crankcase to the intake manifold includes fluidly connecting the crankcase to the intake manifold.

[0146] According to an embodiment, guiding blow-by gas through a extraction line to a hydrocarbon sensor includes activating a vacuum pump positioned between the fuel vapor storage tank and the atmosphere, or activating an extraction pump positioned between the fuel vapor storage tank and the intake manifold to draw in negative pressure relative to atmospheric pressure on the intake manifold; and guiding blow-by gas through a hydrocarbon sensor also includes fluidly connecting the intake manifold to the fuel vapor storage tank.

[0147] According to an embodiment, the invention is further characterized by controlling the pressure in the intake manifold while performing diagnostics, wherein controlling the pressure in the intake manifold includes controlling the position of the throttle valve located in the air intake of the engine.

[0148] According to the present invention, a system for a hybrid electric vehicle is provided, the system comprising: an engine including an intake port, an intake manifold, and an exhaust system; a throttle valve positioned in the intake port; a crankcase forced ventilation system including a crankcase forced ventilation valve positioned in a crankcase forced ventilation line for selectively fluidly connecting the crankcase of the engine to the intake manifold; a motor; an evaporative emission system including a fuel vapor storage filter canister selectively fluidly connected to the atmosphere via a filter canister vent valve positioned in the ventilation line; a vacuum pump positioned in a vacuum pump conduit in parallel with the ventilation line; a first check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line downstream of the filter canister vent valve; a second check valve positioned in the vacuum pump conduit between the vacuum pump and a ventilation line upstream of the filter canister vent valve; and a filter canister extraction valve positioned in an extraction line, wherein the filter canister... The extraction valve selectively fluidly connects the intake manifold to the fuel vapor storage filter canister; a hydrocarbon sensor is positioned in the extraction line between the fuel vapor storage filter canister and the filter canister extraction valve; and a controller stores instructions in a non-transitory memory that, when executed, cause the controller to: command the throttle to open and command the filter canister vent valve to close during a key-off event in which the filter canister load is below a threshold filter canister load, and during driving cycles preceding the key-off event including engine operation; operate the motor to rotate the engine without fuel, thereby directing blow-by gas from the crankcase to the intake manifold via a crankcase forced ventilation valve in at least a partially open position, and also operate a vacuum pump to draw the blow-by gas through the hydrocarbon sensor via the filter canister extraction valve commanded to the open position; and, while drawing the blow-by gas through the hydrocarbon sensor, indicate hydrocarbon sensor degradation in response to the hydrocarbon sensor output being below a threshold output.

[0149] According to an embodiment, the crankcase forced valve is an electronically actuated crankcase forced valve, wherein the controller stores additional instructions to command the crankcase forced valve to a fully open position in order to direct blow-by gas in the crankcase to the intake manifold.

[0150] According to an embodiment, the crankcase forced ventilation valve is a passively actuated mechanical crankcase forced ventilation valve, wherein the controller stores additional instructions to manipulate the pressure in the intake manifold, thereby controlling the passively actuated mechanical crankcase forced ventilation valve to a minimum restraint position in order to direct blow-by gas in the crankcase to the intake manifold.

Claims

1. A method for a hybrid electric vehicle, the method comprising: The blow-by gas is directed from the crankcase of the vehicle's engine to the engine's intake manifold, and then to the fuel vapor storage filter located in the vehicle's evaporative emission system. as well as The hydrocarbon sensor used for feedforward air-fuel ratio control during the extraction of fuel vapor from the fuel vapor storage tank is indicated based on the response of the hydrocarbon sensor during the process of guiding blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage tank.

2. The method of claim 1, wherein guiding blow-by includes a key-off condition after the engine is in operation to propel the vehicle in a driving cycle.

3. The method of claim 1, wherein directing blow-by gas to the intake manifold includes opening a crankcase forced ventilation valve located in a line connecting the crankcase to the intake manifold.

4. The method of claim 3, wherein the crankcase forced ventilation valve is electronically actuated, and wherein the crankcase forced ventilation valve is electronically actuated to a fully open position to direct blow-by gas into the intake manifold.

5. The method of claim 3, wherein the crankcase forced ventilation valve is passively mechanically actuated, and wherein the crankcase forced ventilation valve is controlled to a minimum restraint position to direct blow-by gas to the intake manifold.

6. The method of claim 1, further comprising commanding a throttle valve positioned in the intake port of the engine to fully open, wherein the throttle valve is electronically actuated to direct blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

7. The method of claim 1, wherein directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter further comprises actuating a vacuum pump positioned between the fuel vapor storage filter and the atmosphere to draw negative pressure relative to atmospheric pressure on the intake manifold.

8. The method of claim 7, wherein the vacuum pump is located in the ventilation duct between the fuel vapor storage filter and the atmosphere.

9. The method of claim 8, wherein the vacuum pump is located in a vacuum pump duct in parallel with the ventilation duct, rather than in the ventilation duct.

10. The method of claim 1, wherein indicating whether the hydrocarbon sensor is operating as desired includes indicating hydrocarbon sensor degradation in response to the hydrocarbon sensor output falling below a threshold output during the process of directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter.

11. The method of claim 1, wherein directing blow-by gas from the intake manifold to the fuel vapor storage filter comprises fluidly connecting the intake manifold to the fuel vapor storage filter, and further comprises rotating the engine without fuel and without spark.

12. The method of claim 1, wherein directing blow-by gas from the crankcase to the intake manifold and then to the fuel vapor storage filter further includes an indication that the load on the fuel vapor storage filter is below a threshold filter load.

13. A system for a hybrid electric vehicle, the system comprising: An engine, the engine including an air intake, an intake manifold and an exhaust system; Throttle valve, wherein the throttle valve is positioned in the air intake; A crankcase forced ventilation system, the crankcase forced ventilation system including a crankcase forced ventilation valve located in a crankcase forced ventilation line for selectively fluidly connecting the crankcase of the engine to the intake manifold; motor; An evaporative emission system, comprising a fuel vapor storage filter canister selectively fluidly connected to the atmosphere via a filter canister vent valve located in a ventilation duct; A vacuum pump, wherein the vacuum pump is positioned in a vacuum pump conduit connected in parallel with the ventilation duct; A first check valve is positioned in the vacuum pump conduit between the vacuum pump and the ventilation line downstream of the filter canister vent valve. A second check valve is located in the vacuum pump conduit between the vacuum pump and the ventilation line upstream of the filter canister vent valve. A filter canister extraction valve, positioned in the extraction line, selectively fluidly connects the intake manifold to the fuel vapor storage filter canister. Hydrocarbon sensor, the hydrocarbon sensor being positioned in the extraction line between the fuel vapor storage tank and the tank extraction valve; and The controller stores instructions in non-transitory memory, which, when executed, cause the controller to: In the event of a key-off event where the fuel vapor storage filter canister's canister loading state is below a threshold canister loading state, and in the case of engine operation during a driving cycle preceding the key-off event: The command opens the throttle valve and the command closes the filter canister vent valve; The motor is operated to rotate the engine without fuel, thereby directing blow-by gas in the crankcase to the intake manifold via the crankcase forced ventilation valve, which is at least partially open, and the vacuum pump is also operated to draw the blow-by gas through the hydrocarbon sensor via the filter canister extraction valve, which is commanded to be open. as well as While the blow-by gas is being drawn through the hydrocarbon sensor, the hydrocarbon sensor is indicated to be degraded in response to the output of the hydrocarbon sensor falling below a threshold output.

14. The system of claim 13, wherein the crankcase forced ventilation valve is an electronically actuated crankcase forced ventilation valve, and wherein the controller stores additional instructions to command the crankcase forced ventilation valve to a fully open position so as to direct blow-by gas in the crankcase to the intake manifold.

15. The system of claim 13, wherein the crankcase forced ventilation valve is a passively actuated mechanical crankcase forced ventilation valve, and wherein the controller stores additional instructions to manipulate the pressure in the intake manifold to control the passively actuated mechanical crankcase forced ventilation valve to a minimum restraint position so as to direct blow-by gas in the crankcase to the intake manifold.

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