Method and system for adjusting pressure in fuel tank

Abstract

The present disclosure provides methods and systems for adjusting pressure in a fuel tank. Methods and systems for diagnosing an evaporative emission system are discussed. An exemplary method includes diagnosing a venturi pump of an evaporative emission system based on feedback from an evaporative leak check module (ELCM) pressure sensor and a fuel tank pressure sensor (FTPT). An engine of the vehicle is turned off during the diagnosis.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to methods and systems for controlling pressure and vacuum in a fuel tank. BACKGROUND OF THE INVENTION

[0002] As efforts continue to minimize vehicle emissions, vehicles are equipped with catalytic converters and storage devices configured to process or store emissions. Exemplary storage devices can include a fuel vapor canister configured to store fuel vapor during conditions where the vapor would otherwise flow to the atmosphere. When the engine is running or when the fuel tank pressure is low, a signal can be sent to the canister to release the vapor. By doing so, leakage of the vapor to the atmosphere can be reduced.

[0003] The canister can be arranged within an evaporative emissions control system that includes multiple components for controlling vapor flow, fuel tank depressurization rate, etc. Government regulations require these components to have diagnostic procedures to determine their operation. Due to the pressure variations in the system, dependence on engine operation, and ambient temperature, diagnosing components of the evaporative emissions control system can be challenging. SUMMARY OF THE INVENTION

[0004] The inventors herein have recognized the above problems and have developed a method that at least partially addresses them. One method includes diagnosing a venturi pump of an evaporative emissions system based on feedback from an evaporative leak check module (ELCM) pressure sensor and a fuel tank pressure sensor (FTPT). In this way, the venturi pump can be diagnosed via pre-existing hardware, resulting in minimal addition for performing the diagnosis.

[0005] When understood alone or in conjunction with the drawings, the above and other advantages and features of the present specification will be readily apparent from the following detailed description.

[0006] It should be understood that the above Summary of the Invention is provided to introduce in a simplified form a series of concepts further described in the Detailed Description. This is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An exemplary internal combustion engine of a vehicle is shown;

[0008] Figure 2 An exemplary powertrain of a vehicle including the engine is shown;

[0009] Figure 3 A block diagram of an exemplary evaporative emissions system for a vehicle is shown;

[0010] Figure 4A and Figure 4B An exemplary method for diagnosing an evaporative emissions system of a vehicle is shown;

[0011] Figure 5 A sequence of operations of an evaporative emissions system that performs Figure 4A and Figure 4B is shown; and

[0012] Figure 6A and Figure 6B Exemplary positions of a switching valve (COV) of an evaporative leak check module (ELCM) of an evaporative emissions system are shown. DETAILED DESCRIPTION

[0013] The following description relates to systems and methods for diagnosing an injector of an evaporative emissions system. Figure 1 An exemplary internal combustion engine of a vehicle is shown. Figure 2 An exemplary powertrain of a vehicle including the engine is shown. Figure 3 A block diagram of an exemplary evaporative emissions system for a vehicle is shown. Figure 4A and Figure 4B An exemplary method for diagnosing an evaporative emissions system of a vehicle is shown. Figure 5 A sequence of operations of an evaporative emissions system that performs Figure 4A and Figure 4B is shown. Figure 6A and Figure 6B Exemplary positions of a switching valve (COV) of an evaporative leak check module (ELCM) of an evaporative emissions system are shown.

[0014] Now referring to Figure 1 , a schematic diagram is shown that depicts one cylinder of a multi-cylinder engine 130 in an engine system 100. Engine 130 may be controlled at least in part by a control system including controller 12 and by input from an autonomous driver or controller 14. Alternatively, a vehicle operator (not shown) may provide input via an input device such as an engine torque, power, or air quantity input pedal (not shown).

[0015] The combustion chamber 132 of engine 130 may include a cylinder formed by cylinder walls 134, with a piston 136 positioned within the cylinder. Piston 136 may be coupled to a crankshaft 140 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 140 may be coupled via an intermediate transmission system to at least one drive wheel of the vehicle. Additionally, a starter motor (not shown) may be coupled to crankshaft 140 via a flywheel to effect a starting operation of engine 130.

[0016] The combustion chamber 132 can receive intake air from the intake manifold 144 via the intake passage 142 and can discharge combustion gases via the exhaust passage 148. The intake passage 142 includes an intake air filter 149. The intake manifold 144 and the exhaust passage 148 can be selectively in communication with the combustion chamber 132 via respective intake valves 152 and exhaust valves 154. In some examples, the combustion chamber 132 can include two or more intake valves and / or two or more exhaust valves.

[0017] In this example, the intake valve 152 and the exhaust valve 154 can be controlled by cam actuation via respective cam actuation systems 151 and 153. The cam actuation systems 151 and 153 can each include one or more cams and can utilize one or more of a cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) system that can be operated by the controller 12 to activate, deactivate (e.g., hold in a closed position within a two-revolution engine cycle), and change the valve operation timing. The positions of the intake valve 152 and the exhaust valve 154 can be determined by position sensors 155 and 157, respectively. In an alternative example, the intake valve 152 and / or the exhaust valve 154 can be controlled by electric valve actuation. For example, the cylinder 132 can alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation including a CPS system and / or a VCT system.

[0018] The fuel injector 169 is shown as being directly coupled to the combustion chamber 132 to directly inject fuel into the combustion chamber in proportion to the pulse width of a signal received from the controller 12. In this way, the fuel injector 169 provides so-called fuel direct injection into the combustion chamber 132. For example, the fuel injector can be mounted in the side of the combustion chamber or in the top of the combustion chamber. Fuel can be delivered to the fuel injector 169 via a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some examples, the combustion chamber 132 can alternatively or additionally include a fuel injector arranged in the intake manifold 144 in the following configuration: providing so-called fuel intake port injection into the intake passage upstream of the combustion chamber 132.

[0019] Spark is provided to the combustion chamber 132 via a spark plug 166. The ignition system can also include an ignition coil (not shown) for increasing the voltage supplied to the spark plug 166. In other examples (such as a diesel engine), the spark plug 166 can be omitted.

[0020] The intake passage 142 may include an intake throttle 162 having a throttle plate 164. In this particular example, the position of the throttle plate 164 may be changed by the controller 12 via a signal provided to an electric motor or actuator included in the throttle 162, and this configuration is commonly referred to as electronic throttle control (ETC). In this way, the throttle 162 can be operated to vary the intake air provided to the combustion chamber 132 and other engine cylinders. The position of the throttle plate 164 may be provided to the controller 12 via a throttle position signal. The intake passage 142 may include a mass air flow sensor 120 and a manifold air pressure sensor 122 for sensing the amount of air entering the engine 130. The atmospheric pressure may be determined via the sensor 121.

[0021] The exhaust sensor 127 is shown coupled to the exhaust passage 148 upstream of the emission control device 170 in accordance with the exhaust flow direction. The sensor 127 may be any 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 two-state oxygen sensor or EGO, a HEGO (heated EGO), NO x , HC, or CO sensor. In one example, the upstream exhaust sensor 127 is a UEGO configured to provide an output, such as a voltage signal, that is proportional to the amount of oxygen present in the exhaust. The controller 12 converts the oxygen sensor output to an exhaust air-fuel ratio via an oxygen sensor transfer function.

[0022] The emission control device 170 is shown disposed along the exhaust passage 148 downstream of the exhaust sensor 127. The device 170 may be a three-way catalyst (TWC), a NO x trap, various other emission control devices, or combinations thereof. In some examples, during operation of the engine 130, the emission control device 170 may be periodically reset by operating at least one cylinder of the engine within a particular air-fuel ratio.

[0023] The controller 12 is in Figure 1Shown as a microcomputer, the microcomputer includes a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values shown in this specific example as a read-only memory chip 106 (e.g., non-transitory memory), a random access memory 108, a keep-alive memory 110, and a data bus. In addition to the signals previously discussed, the controller 12 can also receive various signals from sensors coupled to the engine 130, including a measurement of intake mass air flow (MAF) from a mass air flow sensor 120; an engine coolant temperature (ECT) from a temperature sensor 123 coupled to a coolant sleeve 114; an engine position signal from a Hall effect sensor 118 (or other type) sensing the position of the crankshaft 140; a throttle position from a throttle position sensor 165; and a manifold absolute pressure (MAP) signal from a sensor 122. An engine speed signal can be generated by the controller 12 from the crankshaft position sensor 118. The manifold pressure signal also provides an indication of the vacuum or pressure in the intake manifold 144. It should be noted that various combinations of the above sensors can be used, such as using a MAF sensor without using a MAP sensor, or vice versa. During engine operation, the engine torque can be inferred from the output of the MAP sensor 122 and the engine speed. In addition, this sensor, together with the detected engine speed, can be a basis for estimating the charge (including air) drawn into the cylinders. In one example, the crankshaft position sensor 118, which also serves as an engine speed sensor, can generate a predetermined number of equally spaced pulses per revolution of the crankshaft.

[0024] The storage medium read-only memory 106 (e.g., non-transitory memory) can be programmed with computer-readable data representing non-transitory instructions executable by the processor 102 to perform at least part of the methods described below and other variations that are contemplated but not specifically listed. The CPU 102 can sample the output of one or more sensors via an A / D converter within the I / O 104 and store voltages / pressures, etc. into the RAM memory. Thus, the controller 12 can operate actuators to change the operation of the engine 130. Additionally, the controller 12 can publish data, messages, and status information to a human / machine interface 113 (e.g., touch screen display, heads-up display, lights, etc.).

[0025] During operation, each cylinder within the engine 130 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally, the exhaust valve 154 is closed and the intake valve 152 is opened. Air is introduced into the combustion chamber 132 via the intake manifold 144, and the piston 136 moves to the bottom of the cylinder to increase the volume within the combustion chamber 132. The position of the piston 136 near the bottom of the cylinder and at the end of its stroke (e.g., when the combustion chamber 132 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC).

[0026] During the compression stroke, intake valve 152 and exhaust valve 154 are closed. Piston 136 moves toward the cylinder head to compress the air within combustion chamber 132. The point at which piston 136 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 132 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means, such as spark plug 166, resulting in combustion.

[0027] During the expansion stroke, the expanding gases push the piston 136 back to BDC. The crankshaft 140 converts the piston movement into a rotational torque of the rotating shaft. Finally, during the exhaust stroke, the exhaust valve 154 opens to release the combusted air-fuel mixture to the exhaust passage 148, and the piston returns to TDC. Note that the above is shown only as an example, and the intake and exhaust valve opening and / or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0028] As described above, Figure 1 Only one cylinder of a multi-cylinder engine is shown, and each cylinder may similarly include its own set of intake / exhaust valves, fuel injectors, spark plugs, etc.

[0029] Figure 2 is a block diagram of a vehicle 225 including a powertrain or driveline 200 . Figure 2 The powertrain system includes Figure 1The engine 10 shown. The powertrain system 200 is shown to include a vehicle system controller 255, an engine controller 12, a first motor controller 252, a second motor controller 257, a transmission controller 254, an energy storage device controller 253, and a controller 250. The controllers can communicate via a controller area network (CAN) 299. Each of the controllers can provide information to the other controllers, such as power output limits (e.g., power output of a device or component that must not be exceeded by control), power input limits (e.g., power input of a device or component that must not be exceeded by control), power output of the controlled device, sensor and actuator data, diagnostic information (e.g., information about a degraded transmission, information about a degraded engine, information about a degraded motor, information about a degraded brake caliper). In addition, the vehicle system controller 255 can provide commands to the engine controller 12, the motor controller 252, the transmission controller 254, and the controller 250 to implement driver input requests and other requests based on vehicle operating conditions.

[0030] For example, in response to the driver releasing the driver demand pedal and the vehicle speed, the vehicle system controller 255 can request a desired wheel power or wheel power level to provide a desired rate of vehicle speed reduction. The requested desired wheel power can be provided by the vehicle system controller 255 requesting a first deceleration power from the motor controller 252 and a second deceleration power from the engine controller 12, wherein the first power and the second power provide the desired driveline power at the wheel 216. The vehicle system controller 255 can also request friction braking power via the controller 250. Deceleration powers can be referred to as negative powers because they slow down the driveline and wheel rotation. Positive powers can maintain or increase the speed of the driveline and wheel rotation.

[0031] In other examples, the division of control powertrain devices may be related to Figure 2 For example, a single controller may replace the vehicle system controller 255, the engine controller 12, the first motor controller 252, the second motor controller 257, the transmission controller 254, and the controller 250. Alternatively, the vehicle system controller 255 and the engine controller 12 may be a single unit, while the motor controller 252, the transmission controller 254, and the controller 250 are separate controllers.

[0032] In this example, the powertrain 200 may be powered by the engine 10 and the motor 240. In other examples, the engine 10 may be omitted. Figure 1The engine starting system shown is started via an integrated starter / generator BISG 219 or via a powertrain integrated starter / generator (ISG) 240, also referred to as an integrated starter / generator. The temperature of the BISG 219 can be determined via an optional BISG temperature sensor 203. The powertrain ISG 240 (e.g., a high voltage (operating at greater than 30 volts) electric machine) can also be referred to as an electric machine, motor, and / or generator. In addition, the power of the engine 10 can be adjusted via power actuators 204 such as fuel injectors, throttles, etc.

[0033] The powertrain 200 is shown to include an integrated starter / generator (ISG) 219. The ISG 219 may be coupled to the crankshaft 40 of the engine 10 via a coupling 231. Alternatively, the ISG 219 may be directly coupled to the crankshaft 40. The ISG 219 may provide negative torque to the powertrain 200 when charging a higher voltage electrical energy storage device 262 (e.g., a traction battery). The ISG 219 may also provide positive torque to rotate the powertrain 200 via energy supplied by a lower voltage electrical energy storage device (e.g., a battery or capacitor) 263. In one example, the electrical energy storage device 262 may output a higher voltage (e.g., 48 volts) than the electrical energy storage device 263 (e.g., 12 volts). The DC / DC converter 245 may allow electrical energy to be exchanged between the high voltage bus 291 and the low voltage bus 292. The high voltage bus 291 is electrically coupled to the inverter 246 and the higher voltage electrical energy storage device 262. The low voltage bus 292 is electrically coupled to the lower voltage electrical energy storage device 263 and the sensors / actuators / accessories 279. The electrical accessories 279 may include, but are not limited to, front and rear windshield resistive heaters, vacuum pumps, climate control fans, and lights. The inverter 246 converts DC power to AC power, and vice versa, to enable power to be transferred between the ISG 219 and the electrical energy storage device 262. Likewise, the inverter 247 converts DC power to AC power, and vice versa, to enable power to be transferred between the ISG 240 and the electrical energy storage device 262.

[0034] The engine output power can be transmitted to the input side or first side 235 of the powertrain disconnect clutch through the dual mass flywheel 215. The disconnect clutch 236 can be electrically or hydraulically actuated. The downstream side or second side 234 of the disconnect clutch 236 is shown as being mechanically coupled to the ISG input shaft 237.

[0035] ISG 240 is operable to provide power to powertrain 200 or, in a regenerative mode, convert powertrain power into electrical energy for storage in electrical energy storage device 262. ISG 240 is in electrical communication with energy storage device 262. ISG 240 has a Figure 1219 or BISG 219 shown. In addition, ISG 240 directly drives powertrain 200 or is directly driven by powertrain 200. There are no couplings, gears, or chains connecting ISG 240 to powertrain 200. Instead, ISG 240 rotates at the same rate as powertrain 200. Electrical energy storage device 262 (e.g., a high voltage battery or power source) can be a battery, a capacitor, or an inductor. The downstream side of ISG 240 is mechanically connected to pump impeller 285 of torque converter 206 via shaft 241. The upstream side of ISG 240 is mechanically connected to disconnect clutch 236. ISG 240 can provide positive or negative power to powertrain 200 by acting as a motor or generator as directed by motor controller 252.

[0036] The torque converter 206 includes a turbine 286 to output power to the input shaft 270. The input shaft 270 mechanically couples the torque converter 206 to the automatic transmission 208. The torque converter 206 also includes a torque converter bypass lockup clutch 212 (TCC). When the TCC is locked, power is directly transferred from the pump wheel 285 to the turbine 286. The TCC is electrically operated by the controller 254. Alternatively, the TCC can be hydraulically locked. In one example, the torque converter can be referred to as a component of the transmission.

[0037] When the torque converter lockup clutch 212 is fully disengaged, the torque converter 206 transmits the engine power to the automatic transmission 208 via the fluid transfer between the torque converter turbine 286 and the torque converter pump wheel 285, thereby achieving torque multiplication. In contrast, when the torque converter lockup clutch 212 is fully engaged, the engine output power is directly transmitted to the input shaft 270 of the transmission 208 via the torque converter clutch. Alternatively, the torque converter lockup clutch 212 can be partially engaged, thereby enabling the amount of power directly transmitted to the transmission to be adjusted. The transmission controller 254 can be configured to adjust the amount of power transmitted by the torque converter 212 by adjusting the torque converter lockup clutch in response to various engine operating conditions or based on the driver's engine operation request.

[0038] The torque converter 206 also includes a pump 283 that pressurizes fluid to operate the disconnect clutch 236, the forward clutch 210, and the range clutch 211. The pump 283 is driven via an impeller 285 that rotates at the same speed as the ISG 240.

[0039] The automatic transmission 208 includes a gear clutch (e.g., gear 1 to gear 10) 211 and a forward clutch 210. The automatic transmission 208 is a fixed ratio transmission. Alternatively, the transmission 208 may be a continuously variable transmission capable of simulating a fixed gear ratio transmission and a fixed gear ratio. The gear clutch 211 and the forward clutch 210 may be selectively engaged to change the ratio of the actual total number of revolutions of the input shaft 270 to the actual total number of revolutions of the wheels 216. The gear clutch 211 may be engaged or disengaged by adjusting the fluid supplied to the clutch via the shift control solenoid valve 209. The power output from the automatic transmission 208 may also be relayed to the wheels 216 via the output shaft 260 to propel the vehicle. Specifically, the automatic transmission 208 may transmit the input drive power at the input shaft 270 in response to the vehicle driving conditions before transmitting the output drive power to the wheels 216. The transmission controller 254 selectively activates or engages the TCC 212, the gear clutch 211, and the forward clutch 210. The transmission controller also selectively deactivates or disengages the TCC 212 , the range clutch 211 , and the forward clutch 210 .

[0040] Frictional force may be applied to wheel 216 by engaging friction wheel brake caliper 218. In one example, friction wheel brake caliper 218 may be engaged in response to a human driver pressing their foot on a foot pedal (not shown) and / or in response to a command within brake caliper controller 250. Additionally, controller 250 may apply brake caliper 218 in response to information and / or a request issued by vehicle system controller 255. In the same manner, frictional force on wheel 216 may be reduced by disengaging wheel brake caliper 218 in response to a human driver releasing their foot from a foot pedal, controller 250 command, and / or vehicle system controller command and / or information. For example, as part of an automated engine stop procedure, a vehicle brake caliper may apply frictional force to wheel 216 via controller 250. Reaction torque may be determined based on foot pedal position.

[0041] In response to a request to increase the speed of the vehicle 225, the vehicle system controller may obtain a driver demand power or power request from a driver demand pedal or other device. The vehicle system controller 255 then allocates a portion of the requested driver demand power to the engine and the remainder to the ISG or BISG. The vehicle system controller 255 requests engine power from the engine controller 12 and requests ISG power from the motor controller 252. If the ISG power plus the engine power is less than the transmission input power limit (e.g., a threshold that must not be exceeded), the power is delivered to the torque converter 206, which then relays at least a portion of the requested power to the transmission input shaft 270. The transmission controller 254 selectively locks the torque converter clutch 212 and engages the gear via the gear clutch 211 in response to a shift schedule and a TCC lock schedule that may be based on the input shaft power and vehicle speed. In some conditions, when it may be desirable to charge the electrical energy storage device 262, charging power (e.g., negative ISG power) may be requested when there is a non-zero driver demand power. The vehicle system controller 255 may request an increase in engine power to overcome the charging power to meet the driver demand power.

[0042] In response to a request to reduce the speed of the vehicle 225 and provide a regenerative operation, the vehicle system controller may provide a negative desired wheel power (e.g., desired or requested drivetrain wheel power) based on the vehicle speed and pedal position. The vehicle system controller 255 then distributes a portion of the negative desired wheel power to the ISG 240 and the engine 10. The vehicle system controller may also distribute a portion of the requested power to the friction brake caliper 218 (e.g., desired friction reaction wheel power). In addition, the vehicle system controller may notify the transmission controller 254 that the vehicle is in regenerative mode, so that the transmission controller 254 changes the gear 211 based on a unique shifting schedule to improve regeneration efficiency. The engine 10 and the ISG 240 may supply negative power to the transmission input shaft 270, but the negative power provided by the ISG 240 and the engine 10 may be limited by the transmission controller 254, which outputs a transmission input shaft negative power limit (e.g., a threshold that must not be exceeded). In addition, the vehicle system controller 255 or the motor controller 252 may limit the negative power of the ISG 240 (e.g., constrained to less than a threshold negative threshold power) based on the operating conditions of the electrical energy storage device 262. Any portion of the desired negative wheel power that may not be provided by the ISG 240 due to transmission or ISG limitations may be allocated to the engine 10 and / or the friction brake caliper 218 so that the desired wheel power is provided by a combination of negative power (e.g., absorbed power) via the friction brake caliper 218, the engine 10, and the ISG 240.

[0043] Thus, power control of various powertrain components may be monitored by vehicle system controller 255 , with local power control of engine 10 , transmission 208 , motor 240 , and brake caliper 218 provided via engine controller 12 , motor controller 252 , transmission controller 254 , and controller 250 .

[0044] As an example, the engine power output can be controlled by controlling the throttle opening and / or valve timing, valve lift and boost adjustment spark timing, fuel pulse width, fuel pulse timing and / or air charge of a turbocharged engine or a supercharged engine. In the case of a diesel engine, the controller 12 can control the engine power output by controlling the combination of fuel pulse width, fuel pulse timing and air charge. The engine negative engine power can be provided by rotating the engine when the power generated by the engine is not enough to rotate the engine. Therefore, the engine can generate regenerative power by operating at low power when burning fuel, wherein one or more cylinders are deactivated (e.g., not burning fuel), or wherein all cylinders are deactivated and the engine is rotated at the same time. The amount of engine regenerative power can be adjusted by adjusting the engine valve timing. The engine valve timing can be adjusted to increase or decrease the engine compression work. In addition, the engine valve timing can be adjusted to increase or decrease the engine expansion work. In all cases, engine control can be performed cylinder by cylinder to control the engine power output.

[0045] The motor controller 252 may control the power output and electrical energy generation from the ISG 240 by adjusting the current flowing into and out of the field windings and / or armature windings of the ISG, as is known in the art.

[0046] The transmission controller 254 receives the transmission input shaft position via the position sensor 271. The transmission controller 254 can convert the transmission input shaft position into the input shaft speed by derivation of the signal from the position sensor 271 or counting a number of known angular distance pulses within a predetermined time interval. The transmission controller 254 can receive the transmission output shaft torque from the torque sensor 272. Alternatively, the sensor 272 can be a position sensor or a torque and position sensor. If the sensor 272 is a position sensor, the controller 254 can count the shaft position pulses within a predetermined time interval to determine the transmission output shaft speed. The transmission controller 254 can also derive the transmission output shaft speed to determine the rate of change of the transmission output shaft speed. The transmission controller 254, the engine controller 12 and the vehicle system controller 255 can also receive additional transmission information from the sensor 277, which can include but is not limited to a pump output line pressure sensor, a transmission hydraulic sensor (e.g., a gear clutch fluid pressure sensor), an ISG temperature sensor and a BISG temperature, a shift lever sensor and an ambient temperature sensor. The transmission controller 254 may also receive a requested gear input from a shift selector 290 (eg, a human / machine interface device). The shift selector 290 may include positions for gears 1 through N (where N is the number of high gears), D (drive), and P (park).

[0047] The controller 250 receives wheel speed information via the wheel speed sensor 221 and receives a reaction request from the vehicle system controller 255. The controller 250 may provide braking in response to the wheel power command from the vehicle system controller 255. The controller 250 may also provide anti-lock braking and vehicle stability operations to improve vehicle performance. Thus, the controller 250 may provide a wheel power limit (e.g., a threshold negative wheel power that must not be exceeded) to the vehicle system controller 255 so that the negative ISG power does not cause the wheel power limit to be exceeded. For example, if the controller 250 issues a negative wheel power limit of 50 N-m, the ISG power is adjusted to provide a negative power of less than 50 N-m (e.g., 49 N-m) at the wheel, including consideration of the transmission gear transmission.

[0048] Reference now Figure 3, a block diagram of an exemplary evaporative emission system 300 is shown. The evaporative emission system 300 includes a canister purge valve (CPV) 302, a first carbon-filled canister 304, a second carbon-filled canister 306, a third carbon-filled canister 308, an evaporative leak check module (ELCM) 395, a dust box 312, a fuel tank isolation valve (FTIV) 375, and a fuel tank 320. The carbon-filled canisters 304-308 may include activated carbon 311 to store fuel vapor. Relative to the direction of fluid flow, the first carbon-filled canister 304 is an upstream canister, and the third carbon-filled canister 308 is a downstream canister. Figure 3 The system of FIG. 1 shows three carbon-filled canisters, but the principles and methods described herein can be applied to evaporative emission systems having two carbon-filled canisters or more than three carbon-filled canisters. Three existing smaller-volume carbon-filled canisters may be less expensive than one larger carbon-filled canister having the same volume as three smaller-volume carbon-filled canisters.

[0049] Canister purge valve 302 may selectively provide fluid communication between first carbon filled canister 304 and intake manifold 144. Controller 12 may adjust Figure 3 The operating state of each valve is shown. Controller 12 may also receive output from fuel tank pressure sensor 314 .

[0050] In some examples, the evaporative emission control system may also include an evaporative level check monitor (ELCM) 395. The ELCM 395 may be disposed in the conduit 346 and may be configured to control ventilation and / or assist in the detection of evaporative emissions. As an example, the ELCM 395 may include a vacuum pump for applying negative pressure to the fuel system when testing for evaporative emissions. In some embodiments, the vacuum pump may be configured to be reversible. In other words, the vacuum pump may be configured to apply negative pressure or positive pressure to the evaporative emission control system and the fuel system. The ELCM 395 may also include a reference orifice (not shown), a pressure sensor 397, and a switching valve (COV) 396. Therefore, a reference check may be performed, whereby a vacuum may be drawn across the reference orifice, wherein the resulting vacuum level includes a vacuum level indicating that there is no evaporative emission. For example, after the reference check, the fuel system and the evaporative emission control system may be evacuated by the ELCM vacuum pump. In the absence of evaporative emissions, the vacuum may be pulled down to the reference check vacuum level. Alternatively, in the presence of evaporative emissions, the vacuum may not be pulled down to the reference check vacuum level.

[0051] During selected engine and / or vehicle operating conditions, such as after the emission control device light-off temperature has been reached (e.g., a threshold temperature reached after warming up from ambient temperature) and with the engine running, controller 12 can control ELCM 395 switching valve (COV) 396 to enable at least one of the fuel vapor canisters to be fluidly coupled to the atmosphere. For example, except during pressure testing performed on the system, ELCM COV 396 can be configured in a first position (e.g., open), where the first position includes the third canister 308 fluidly coupled to the atmosphere. In one example, under natural intake conditions (e.g., intake manifold vacuum conditions), ELCM COV 396 can be configured in a second position (e.g., closed) to seal the third canister 308 from the atmosphere. By commanding ELCM COV 396 to the second position, the evaporative emission control system and the fuel system can be purged to ascertain the presence or absence of evaporative emissions.

[0052] Each of the carbon filled canisters 304-308 includes a vent port (eg, 304a, 306a, and 308a), a load port (eg, 304b, 306b, and 308b), and a purge port (eg, 304c, 306c, and 308c). Purge ports 306c and 308c are plugged.

[0053] In one example, the ELCM 395 and the ELCM pressure sensor 389 can be used to perform leak detection diagnostics for the fuel system. In some examples, such as examples where the vehicle only includes an internal combustion engine, the ELCM 395 and the ELCM pressure sensor 389 can be omitted. If the ELCM 395 is omitted, a dust box or similar device can be included between the fuel system and the atmosphere. The ELCM pressure sensor 389 can be configured to sense the pressure between the downstream canister (e.g., the third canister 308) and the ELCM 395.

[0054] The evaporative emission system 300 also includes an ejector 330. The ejector 330 is referred to herein as a venturi pump 330. The venturi pump 330 includes a low pressure port 330a, a first power fluid port 330b, and a second power fluid port 330c. When the canister purge valve 302 and the fuel tank isolation valve 375 are open, fuel vapor can flow from the fuel tank 320 to the venturi pump 330. The fuel vapor can flow through the first power fluid port 330b and the second power fluid port 330c of the venturi pump 330, which can draw air and / or fuel vapor into the venturi pump 330 through the low pressure port 330a and the first bypass passage 356 when the first bypass valve 316 is open. The air and / or fuel vapor can flow from the venturi pump 330 to the first carbon-filled canister 304. When engine intake manifold pressure is low and canister purge valve 302 is open, air and / or fuel vapors may flow from first carbon filled canister 304 to engine intake manifold 144 .

[0055] In one example, when the plurality of bypass valves are actuated to an open position, the low pressure port 330a can be directly fluidly coupled to the ELCM 395. The first port 330b can be fluidly coupled to a conduit 360. The first port 330c can be fluidly coupled to a conduit 358. In one example, the conduit 360 and the conduit 358 form separate portions of a load line, which is a fluid passage separated by the venturi pump 330.

[0056] Fuel tank 320 is shown with a fuel fill limit vent valve (FLVV) 333. When fuel tank 320 is filled with fuel 324, FLVV may close to prevent fuel from flowing into conduit 360. When fuel tank 320 is filled and FLVV is closed, pressure may build up in fuel tank 320, causing the fuel fill nozzle ( Figure 3 3 (not shown) prevents fuel from flowing into the fuel tank 320. The fuel tank 320 may also contain fuel vapor 321.

[0057] Conduit 339 couples intake manifold 144 to canister purge valve 302, allowing fluid communication between the two devices. Conduit 340 couples canister purge valve 302 and first carbon-filled canister 304. Conduit 346 couples third carbon-filled canister 308 and COV 390. Conduit 358 couples second motive fluid port 330c of venturi pump 330 to charge port 304b of first carbon-filled canister 304. Conduit 354 couples first carbon-filled canister 304 and second carbon-filled canister 306. Conduit 350 couples third carbon-filled canister 308 and second carbon-filled canister 306.

[0058] The first carbon-filled canister 304 includes a bypass passage or conduit 356 and a bypass valve 316 for selectively allowing and preventing air from flowing through the conduit 356. Similarly, the second carbon-filled canister 306 includes a bypass passage or conduit 352 and a bypass valve 318 for selectively allowing and preventing air from flowing through the conduit 352. Likewise, the third carbon-filled canister 308 includes a bypass passage or conduit 348 and a bypass valve 319 for selectively allowing and preventing air from flowing through the conduit 348. Thus, the conduits 348, 352, and 356 may allow air to flow around the carbon-filled canisters 304, 306, and 308. For example, if the bypass valve 319 is open, air may be drawn from the atmosphere and through the passage 348 without passing through the carbon-filled canister 308, so that the air may ultimately be drawn into the intake manifold 144. The airflow may follow the path of least resistance, and it may pass through the bypass passage if the bypass valve of the bypass passage is open.

[0059] The loading levels of first carbon-filled canister 304, second carbon-filled canister 306, and third carbon-filled canister 308 may be determined via temperature sensors 370 installed therein. Specifically, temperature changes within the carbon-filled canisters may indicate the mass of hydrocarbons stored within the carbon-filled canisters.

[0060] Figure 6A A fuel vapor canister (such as a Figure 3 A first schematic diagram 600 of an evaporative leak check module (ELCM) 395 in a first configuration with the canister 308 vented to atmosphere. Figure 6B A second schematic diagram 650 of the ELCM 395 is shown in a second configuration in which the venturi pump is undergoing diagnostics.

[0061] The ELCM 395 includes a switching valve (COV) 396, a vacuum pump 630, and a pressure sensor 696. In one example, if the ELCM 395 includes the pressure sensor 696, the pressure sensor 696 may be omitted. Figure 3 The vacuum pump 630 may be a reversible pump, such as an impeller pump. The COV 396 may be movable between a first position and a second position. In the first position, Figure 6A As shown, air can flow through the ELCM 395 via the first flow path 620. In the second position, as shown in FIG. Figure 6BAs shown, air can flow through the ELCM 395 via the second flow path 623. The position of the COV 396 can be controlled by the solenoid 610 via the compression spring 603. The ELCM 395 can also include a reference orifice 640. The reference orifice 640 can have a diameter corresponding to the size of the threshold leak to be tested (e.g., 0.02"). In the first position or the second position, the pressure sensor 397 can generate a pressure signal reflecting the pressure within the ELCM 395. The operation of the pump 630 and the solenoid 610 can be controlled via signals received from the controller 12.

[0062] like Figure 6A , in a first configuration, COV 396 is in a first position and pump 630 is disabled. This configuration allows air to flow freely between the atmosphere and the canister via first flow path 620. This configuration may be used, for example, during a canister purge operation, or during other conditions in which the fuel vapor canister is to be vented to the atmosphere. Upon receiving a request for refueling, COV 396 may be actuated to a first position (first position of the ELCM) to facilitate air flow to the canister and vent refueling vapors from the fuel tank to the canister.

[0063] like Figure 6B , COV 396 is in the second position and pump 630 is closed in the first direction. This configuration allows for diagnosis of the venturi pump with a higher vacuum signal. In other examples of the second position, pump 630 can be activated to evacuate the evaporative emission system. When pump 630 is closed (e.g., inactive), pump 630 is sealed and prevents vapor from flowing from conduit 346 to the atmosphere. When pump 630 is turned on (e.g., active), pump 630 forces air from conduit 346 to the atmosphere.

[0064] Reference now Figure 4A and Figure 4B , an exemplary method 400 for operating an evaporative emission system is shown. Specifically, the method may include performing a diagnostic on a venturi pump disposed in a load line of the evaporative emission system. The method may also include adjusting an operating parameter in response to a diagnostic degradation (e.g., a failure). At least a portion of the method 400 may be included as executable instructions stored in a non-transitory memory such as a Figures 1 to 3 as well as Figures 6A to 6B When implemented via executable instructions stored in a controller memory Figure 4A and Figure 4B When the method is implemented, the method can cause the controller to adjust the actuator in the real world and receive data and signals from the sensors described in this article.

[0065] At 402, method 400 determines vehicle operating conditions. Vehicle operating conditions may include, but are not limited to, ambient air temperature, engine speed, engine air flow, driver demand torque or power, intake manifold pressure, spark timing, barometric pressure, intake port pressure, fuel tank pressure, carbon-filled canister hydrocarbon loading, and engine air-fuel ratio. Method 400 may determine or infer these conditions from the various sensors mentioned herein.

[0066] At 404, method 400 may include determining whether the engine is off. If the engine is not being fueled, the engine may be off. As another example, if no combustion occurs at the engine, the engine may be off.

[0067] If the engine is not shut down, then at 406, method 400 may include not diagnosing the injectors of the evaporative emissions system. If the engine is shut down, then at 408, method 400 may include sensing the fuel tank pressure. The fuel tank pressure may be sensed via the FTPT.

[0068] At 410, method 400 includes determining whether the fuel tank pressure is greater than or equal to a threshold pressure. In one example, the threshold pressure is equal to a non-zero positive value. The threshold pressure may be based on a pressure rise in the fuel tank due to a higher ambient temperature and / or a temperature rise in the liquid fuel due to the engine running for a period of time before the engine is shut down. In one example, the threshold pressure is equal to 30 inH 2 In one example, the fuel tank pressure may be compared to a threshold pressure when the vehicle is parked and immobile. Additionally or alternatively, the vehicle may be in electric-only mode and propelled only by the electric motor when the fuel tank pressure is compared to the threshold pressure to determine whether the entry conditions for the injector diagnostic are met.

[0069] If the fuel tank pressure is less than (eg, not greater than or equal to) the threshold pressure, at 412 , method 400 may include continuing to monitor the fuel tank pressure.

[0070] If the fuel tank pressure is greater than or equal to the threshold pressure, at 414 , method 400 may include closing the ELCM switch valve (COV). The evaporative emission system may be sealed from the atmosphere, which may provide a higher signal amplitude during diagnostics. By doing so, the effectiveness of the diagnostics is improved.

[0071] At 416 , method 400 may include opening the first, second, and third bypass valves. The injector and the ELCM pressure sensor may now be directly fluidly coupled to each other. In this manner, the ELCM pressure sensor may be based on the functionality of the injector.

[0072] At 418, method 400 may include opening the FTIV and CPV. In one example, the FTIV and CPV are commanded to open simultaneously via a controller. The fuel tank may be fluidly coupled to the injector. Additionally, the first canister may be fluidly coupled to the injector. In this manner, each of the ports of the injector may be fluidly coupled to a separate portion of the evaporative emissions system.

[0073] At 420, method 400 includes sensing ELCM pressure. In one example, the ELCM pressure may be sensed by an ELCM pressure sensor. The ELCM pressure sensor may provide feedback to the controller regarding the ELCM pressure.

[0074] At 422, method 400 may include determining whether the ELCM pressure is equal to a threshold pressure. In one example, the threshold vacuum may be equal to a non-zero number. The threshold vacuum may be based on an expected vacuum generated by the injectors in response to the injectors opening to the fuel tank. In one example, the threshold vacuum may be a dynamic value based on the fuel tank pressure, where as the fuel tank pressure increases, the threshold vacuum increases (e.g., the pressure becomes more negative). In one example, the threshold vacuum is equal to -4 inH. 2 O.

[0075] If the ELCM pressure is equal to the threshold vacuum, then at 424 , method 400 may include determining if the fuel tank pressure is decreasing. The fuel tank pressure is sensed via the FTPT. The FTPT may provide feedback to the controller regarding the fuel tank pressure.

[0076] If the fuel tank pressure is decreasing, method 400 may include determining that the injector is not degraded at 426. Each of the ports of the injector may be open to a corresponding component of the evaporative emission system, allowing pressure to flow as expected. In one example, the flag is not set and the operation of the evaporative emission system is not adjusted.

[0077] If the ELCM pressure is not equal to the threshold vacuum (e.g., greater than the threshold vacuum), or if the fuel tank pressure has not decreased, the injector is degraded and a non-negative pressure (e.g., positive pressure or zero pressure) is sensed. At 428, method 400 may include determining if the ELCM pressure is equal to zero. If the ELCM pressure is equal to zero, at 430, method 400 may include determining that a low pressure port connecting the injector to the ELCM is blocked.

[0078] At 432, method 400 may include reducing the rate of decompression of the fuel system. When the low pressure port is blocked, the ELCM may be unable to decompress the fuel tank. In one example, the FTIV may be moved to a less open position to reduce the amount of vacuum directed to the fuel tank in order to reduce the rate of decompression. Additionally or alternatively, a flag may be set and the vehicle operator may be notified via text, email, infotainment system alert, or other communication means that maintenance is requested.

[0079] If zero pressure is not detected, method 400 may include detecting a positive pressure at 434. The positive pressure may correspond to atmospheric pressure or fuel tank pressure depending on the type of degradation of the injector.

[0080] At 436 , method 400 may include determining whether the fuel tank pressure is decaying. If the fuel tank pressure is not decaying and remains constant, at 438 , method 400 may include determining that the first port is blocked. In one example, when the first port is blocked, the fuel tank may be sealed from the injector.

[0081] At 440, method 400 may include adjusting the refueling rate, including limiting the refueling fill rate and / or fill amount. In one example, fuel tank vapors generated during a refueling event may be trapped in the fuel tank. Thus, a lower fuel tank fill rate may reduce the amount of fuel vapor generated, which may enhance the refueling condition. Additionally or alternatively, the fill amount may be reduced to a portion of the fuel tank fill limit, wherein the reduced fill amount is based on the expected fuel vapor generated according to the refueling rate. Additionally or alternatively, a flag may be set, and the vehicle operator may be notified of the request for maintenance via text, email, infotainment system alert, or other communication means.

[0082] In some examples, additionally or alternatively, the controller can communicate with a human-machine interface (HMI) and / or a fuel station to adjust the refueling rate, including reducing the refueling filling rate. The HMI can include the vehicle's infotainment system, a vehicle operator's phone, or other device. The controller can indicate injector degradation and suggest to the vehicle operator to reduce the refueling filling rate and / or indicate to the vehicle operator to increase the refueling time. The controller can signal the fuel station (such as a smart fuel station with wireless communication capabilities and controls for modifying refueling conditions) to reduce the refueling filling rate.

[0083] Returning to 436 , if the fuel tank pressure is decaying, method 400 may include determining that the second port is blocked at 442 . When the second port is blocked, fuel tank vapors may flow to a plurality of canisters.

[0084] At 444, method 400 may include adjusting reverse purging of the first canister, including preventing reverse purging of the first canister to the fuel tank. Reverse purging may include flowing vapors from the first canister through a venturi pump, through the FTIV, and directly to the fuel tank. Additionally or alternatively, a flag may be set and a vehicle operator may be notified of the requested maintenance via text, email, infotainment system alert, or other communication means.

[0085] Now go to Figure 5 , which shows a graph 500 showing the execution Figure 4A and Figure 4B Graph 510 shows engine conditions. Graph 520 shows fuel tank pressure, and dashed line 522 indicates a threshold pressure. Graph 530 shows ELCM pressure, and dashed line 532 indicates a threshold vacuum. Graph 540 shows FTIV position. Graph 550 shows COV position. Graph 560 shows CPV position. Graph 570 shows the position of the bypass valve. Graph 580 shows which port of the injector is degraded or whether the injector is not degraded.

[0086] Prior to t1, the engine is shut down. The fuel tank pressure increases due to sunlight contacting the vehicle and / or due to high ambient temperature. At t1, the fuel tank pressure is equal to a pressure greater than a threshold pressure. Thus, the entry conditions for the injector diagnostic are met. The ELCMCOV is commanded to a closed position. The bypass valve is commanded to an open position. The FTIV and CPV are commanded to an open position. Thus, the ELCM is sealed from the atmosphere during the diagnostic period. In addition, the injector is fluidly coupled to each of the ELCM, the first canister, and the fuel tank.

[0087] Between t1 and t2, the ELCM pressure increases to a positive pressure and then begins to decay. At t2, the diagnostic determines that the second port of the injector is degraded.

[0088] The present disclosure provides support for a method that includes diagnosing a venturi pump of an evaporative emission system based on feedback from an evaporative leak check module (ELCM) pressure sensor and a fuel tank pressure sensor (FTPT). A first example of the method also includes determining that the engine of the vehicle is off before the diagnosis, wherein the engine includes the evaporative emission system. A second example of the method that optionally includes the first example includes further including opening a switching valve (COV) of the ELCM before the diagnosis. A third example of the method that optionally includes one or more of the foregoing examples also includes, wherein the evaporative emission system includes at least two fuel vapor storage canisters that are fluidly coupled in series, and further includes opening a bypass valve corresponding to the at least two fuel vapor storage canisters before the diagnosis. A fifth example of the method that optionally includes one or more of the foregoing examples also includes opening a canister purge valve (CPV) and a fuel tank isolation valve (FTIV) before the diagnosis. A fifth example of the method that optionally includes one or more of the foregoing examples also includes, wherein the diagnosis includes indicating that the venturi pump is not degraded in response to the ELCM sensing a negative pressure and the pressure detected by the FTPT decaying over time. A sixth example of the method which optionally includes one or more of the previous examples also includes wherein the diagnosing includes indicating port degradation of the venturi pump in response to the ELCM sensing a positive pressure or zero pressure.

[0089] The present disclosure provides additional support for a vehicle system, the vehicle system comprising: an engine; an evaporative emission system, the evaporative emission system comprising a plurality of canisters and a plurality of canister bypass valves; a venturi pump, the venturi pump disposed in a load line extending from a fuel tank to a first canister of the plurality of canisters; an evaporative leak check module (ELCM), the evaporative leak check module comprising a switching valve (COV) and disposed between the atmosphere and a downstream canister in series with the plurality of canisters; and a controller having computer readable instructions stored on its memory, the computer readable instructions when executed causing the controller to perform a diagnosis of the venturi pump in response to the engine being shut down and a fuel tank pressure being greater than or equal to a threshold pressure. The first example of the vehicle system also includes, wherein the venturi pump comprises: a low pressure port, the low pressure port being fluidly coupled to a conduit housing a first canister bypass valve of the plurality of canister bypass valves; a first port, the first port being fluidly coupled to an interior volume of the fuel tank; and a second port, the second port being fluidly coupled to the first canister. A second example of the vehicle system optionally including the first example also includes, wherein a pressure sensor is arranged between the ELCM and the downstream canister. A third example of the vehicle system optionally including one or more of the foregoing examples also includes, wherein a fuel tank pressure sensor (FTPT) is arranged between the venturi pump and the fuel tank. A fourth example of the vehicle system optionally including one or more of the foregoing examples also includes, wherein the instruction also causes the controller to indicate that the diagnosis is passed in response to the vacuum at the ELCM being equal to the threshold vacuum and the fuel tank pressure decaying. A fifth example of the vehicle system optionally including one or more of the foregoing examples also includes, wherein the instruction also enables the controller to indicate that the diagnosis is degraded in response to the vacuum not flowing from the venturi pump to the ELCM. A sixth example of the vehicle system optionally including one or more of the foregoing examples also includes, wherein the instruction also causes the controller to close the COV, open the multiple canister bypass valves, open the fuel tank isolation valve arranged between the fuel tank and the venturi pump, and open the canister extraction valve (CPV) arranged between the first canister and the engine. A seventh example of the vehicle system optionally including one or more of the preceding examples also includes wherein the instructions further cause the controller to adjust one of a depressurization rate of the fuel tank, a refueling rate, and a reverse purging of the first canister in response to the diagnostic degradation.

[0090] The present disclosure provides additional support for a hybrid vehicle system, the hybrid vehicle system comprising: an engine; a plurality of filter canisters, the plurality of filter canisters being arranged in series; an evaporative leak check module (ELCM), the evaporative leak check module including a switching valve (COV) and being arranged between the atmosphere and a downstream filter canister connected in series with the plurality of filter canisters; a venturi pump, the venturi pump being arranged in a load line extending from a fuel tank to an upstream filter canister among the plurality of filter canisters, the venturi pump including a low pressure port fluidly coupled to the ELCM, a first port fluidly coupled to the load line, and a second port fluidly coupled to the load line; a pressure sensor, the pressure sensor being arranged between the ELCM and the downstream filter canister; a fuel tank pressure sensor (FTPT), the fuel tank pressure sensor being arranged between the venturi pump and the fuel tank; and a controller, the controller having computer readable instructions stored on a memory thereof, the computer readable instructions, when executed, causing the controller to perform a diagnosis of the venturi pump in response to the engine being shut down and a fuel tank pressure being greater than or equal to a threshold pressure. The first example of the hybrid vehicle system also includes, wherein the instructions also enable the controller to indicate that the diagnosis has passed in response to the pressure sensor sensing a negative pressure and the FTPT sensing a decaying fuel tank pressure. The second example of the hybrid vehicle system also includes, wherein the instructions also enable the controller to indicate that the diagnosis has not passed in response to the pressure sensor sensing a non-negative pressure. The third example of the hybrid vehicle system that optionally includes one or more of the foregoing examples also includes, wherein the instructions also enable the controller to adjust one of the decompression rate of the fuel tank, the fuel replenishment rate of the fuel tank, and the reverse extraction of the upstream filter canister in response to the diagnosis not passing. The fourth example of the hybrid vehicle system that optionally includes one or more of the foregoing examples also includes, wherein the multiple filter canisters also include a filter canister arranged between the upstream filter canister and the downstream filter canister.

[0091] It should be noted that the example control and estimation procedures included herein can be used with various engine and / or vehicle system configurations. In addition, the methods described herein can be a combination of actions taken by a controller in the physical world and instructions within the controller. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination with various sensors, actuators, and other engine hardware. The specific procedures described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Thus, the various actions, operations, and / or functions shown may be executed in the order shown, in parallel, or omitted in some cases. Likewise, 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 actions, operations, and / or functions shown may be repeatedly performed according to the specific strategy used. In addition, the actions, operations, and / or functions may be graphically represented as codes in a non-transitory memory of a computer-readable storage medium programmed into an engine control system, wherein the actions described are implemented by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0092] This specification ends here. Many variations and modifications will occur to those skilled in the art after reading this specification without departing from the spirit and scope of this specification. For example, I3, I4, I5, V6, V8, V10 and V12 engines operating in natural gas, gasoline, diesel or alternative fuel configurations may benefit from using this specification.

[0093] The appended claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. The claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

[0094] According to the present invention, a method includes diagnosing a venturi pump of an evaporative emissions system based on feedback from an evaporative leak check module (ELCM) pressure sensor and a fuel tank pressure sensor (FTPT).

[0095] In one aspect of the invention, the method includes determining that an engine of a vehicle is shut down prior to the diagnosing, wherein the engine includes the evaporative emissions system.

[0096] In one aspect of the invention, the method comprises opening a switching valve (COV) of the ELCM prior to the diagnosing.

[0097] In one aspect of the present invention, the evaporative emission system includes at least two fuel vapor storage canisters fluidly coupled in series, and further includes opening bypass valves corresponding to the at least two fuel vapor storage canisters prior to the diagnosing.

[0098] In one aspect of the present invention, the method includes opening a canister purge valve (CPV) and a fuel tank isolation valve (FTIV) prior to said diagnosing.

[0099] In one aspect of the invention, the diagnosing includes indicating that the venturi pump is not degraded in response to the ELCM sensing a negative pressure or a decay in pressure detected by the FTPT over time.

[0100] In one aspect of the invention, the diagnosing includes indicating port degradation of the venturi pump in response to the ELCM sensing a positive pressure or zero pressure.

[0101] According to the present invention, a vehicle system is provided, which has: an engine; an evaporative emission system, the evaporative emission system including a plurality of filter canisters and a plurality of filter canister bypass valves; a venturi pump, the venturi pump being arranged in a load line extending from a fuel tank to a first filter canister among the plurality of filter canisters; an evaporative leak check module (ELCM), the evaporative leak check module including a switching valve (COV) and being arranged between the atmosphere and a downstream filter canister connected in series with the plurality of filter canisters; and a controller, the controller having computer-readable instructions stored on its memory, the computer-readable instructions, when executed, causing the controller to perform a diagnosis of the venturi pump in response to the engine being shut down and a fuel tank pressure being greater than or equal to a threshold pressure.

[0102] According to one embodiment, the venturi pump includes a low pressure port fluidly coupled to a conduit housing a first canister bypass valve of the plurality of canister bypass valves, a first port fluidly coupled to an interior volume of the fuel tank, and a second port fluidly coupled to the first canister.

[0103] According to one embodiment, the invention further features a pressure sensor disposed between the ELCM and the downstream canister.

[0104] According to one embodiment, the invention is also characterized by a fuel tank pressure sensor (FTPT) arranged between the venturi pump and the fuel tank.

[0105] According to one embodiment, the instructions further cause the controller to indicate that the diagnostic passed in response to vacuum at the ELCM being equal to a threshold vacuum and the fuel tank pressure decaying.

[0106] According to one embodiment, the instructions further cause the controller to indicate degradation of the diagnostic in response to vacuum not flowing from the venturi pump to the ELCM.

[0107] According to one embodiment, the instructions further cause the controller to close the COV, open the plurality of canister bypass valves, open a fuel tank isolation valve disposed between the fuel tank and the venturi pump, and open a canister purge valve (CPV) disposed between the first canister and the engine.

[0108] According to one embodiment, the instructions further cause the controller to adjust one of a depressurization rate of the fuel tank, a refueling rate, and a reverse purging of the first canister in response to the diagnostic degradation.

[0109] According to the present invention, a hybrid vehicle system is provided, which has: an engine; a plurality of filter canisters, the plurality of filter canisters being arranged in series; an evaporative leak check module (ELCM), the evaporative leak check module including a switching valve (COV) and being arranged between the atmosphere and a downstream filter canister connected in series with the plurality of filter canisters; a venturi pump, the venturi pump being arranged in a load line extending from a fuel tank to an upstream filter canister among the plurality of filter canisters, the venturi pump including a low-pressure port fluidly connected to the ELCM, a first port fluidly connected to the load line, and a second port fluidly connected to the load line; a pressure sensor, the pressure sensor being arranged between the ELCM and the downstream filter canister; a fuel tank pressure sensor (FTPT), the fuel tank pressure sensor being arranged between the venturi pump and the fuel tank; and a controller, the controller having computer-readable instructions stored on its memory, the computer-readable instructions, when executed, causing the controller to: perform a diagnosis of the venturi pump in response to the engine being shut down and a fuel tank pressure being greater than or equal to a threshold pressure.

[0110] According to one embodiment, the instructions further enable the controller to indicate that the diagnostic passed in response to the pressure sensor sensing a negative pressure and the FTPT sensing a decaying fuel tank pressure.

[0111] According to one embodiment, the instructions further enable the controller to indicate that the diagnostic has failed in response to the pressure sensor sensing a non-negative pressure.

[0112] According to one embodiment, the instructions further enable the controller to adjust one of a depressurization rate of the fuel tank, a refueling rate of the fuel tank, and a reverse purge of the upstream canister in response to the diagnostic failing.

[0113] According to one embodiment, the plurality of canisters further includes a canister disposed between the upstream canister and the downstream canister.

Claims

1. A method comprising: The venturi pump of the evaporative emissions system is diagnosed based on feedback from the evaporative leak check module (ELCM) pressure sensor and the fuel tank pressure sensor (FTPT). 2 . The method of claim 1 , further comprising determining that an engine of a vehicle is off prior to said diagnosing, wherein said engine includes said evaporative emissions system.

3. The method of claim 1, further comprising opening a switching valve (COV) of the ELCM prior to the diagnosing. 4 . The method of claim 1 , wherein the evaporative emission system includes at least two fuel vapor storage canisters fluidly coupled in series, further comprising opening bypass valves corresponding to the at least two fuel vapor storage canisters prior to the diagnosing. 5 . The method of claim 1 , further comprising opening a canister purge valve (CPV) and a fuel tank isolation valve (FTIV) prior to said diagnosing. 6 . The method of claim 1 , wherein the diagnosing includes indicating that the venturi pump is not degraded in response to the ELCM sensing a negative pressure or a pressure decay over time detected by the FTPT. 7 . The method of claim 6 , wherein the diagnosing includes indicating port degradation of the venturi pump in response to the ELCM sensing positive pressure or zero pressure.

8. A vehicle system comprising: engine; an evaporative emission system, the evaporative emission system comprising a plurality of canisters and a plurality of canister bypass valves; a venturi pump disposed in a load line extending from a fuel tank to a first canister of the plurality of canisters; an evaporative leak check module (ELCM) including a switching valve (COV) and disposed between atmosphere and a series-connected downstream canister of the plurality of canisters; and A controller having computer readable instructions stored on a memory thereof, the computer readable instructions, when executed, causing the controller to: A diagnostic of the venturi pump is performed in response to the engine being shut down and a fuel tank pressure being greater than or equal to a threshold pressure.

9. The vehicle system of claim 8, wherein the venturi pump comprises: a low pressure port fluidly coupled to a conduit housing a first canister bypass valve of the plurality of canister bypass valves; a first port fluidly coupled to an interior volume of the fuel tank; and a second port fluidly coupled to the first canister. 10 . The vehicle system of claim 8 , further comprising a pressure sensor disposed between the ELCM and the downstream canister.

11. The vehicle system of claim 8, further comprising a fuel tank pressure sensor (FTPT) disposed between the venturi pump and the fuel tank.

12. The vehicle system of claim 8 wherein the instructions further cause the controller to indicate that the diagnostic passed in response to vacuum at the ELCM being equal to a threshold vacuum and the fuel tank pressure decaying.

13. The vehicle system of claim 8 wherein the instructions further cause the controller to indicate a failure of the diagnostic in response to vacuum not flowing from the venturi pump to the ELCM.

14. The vehicle system of claim 8, wherein the instructions further cause the controller to close the COV, open the plurality of canister bypass valves, open a fuel tank isolation valve disposed between the fuel tank and the venturi pump, and open a canister purge valve (CPV) disposed between the first canister and the engine.

15. The vehicle system of claim 8 wherein the instructions further cause the controller to adjust one of a depressurization rate of the fuel tank, a refueling rate, and a reverse purging of the first canister in response to the diagnostic failure.

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