Method and system for diagnosing evaporative emission control system

Abstract

The present disclosure provides methods and systems for diagnosing an evaporative emission control system. Methods and systems are presented for diagnosing the operation of an evaporative emission system comprising two carbon-filled fuel vapor storage canisters arranged in parallel. In one example, operation of a first canister vent valve, a second canister vent valve, and a canister purge valve is adjusted to diagnose cleavage and clogging within the evaporative emission system.

Description

Technical Field

[0001] This specification generally relates to methods and systems for evaluating the operation of parallel-arranged carbon-filled fuel vapor storage filter tanks. Background Technology

[0002] To date, many heavy-duty vehicles have relied on external fuel vapor recovery systems to capture fuel vapors that may be generated as the vehicle's fuel tank fills. However, even heavy-duty vehicles are moving towards onboard fuel vapor recovery systems. Heavy-duty vehicles may include large fuel tanks for storing fuel, enabling them to operate under high loads for long-distance travel. When a vehicle's fuel tank is filled, the volume of the large tank can lead to the generation of significant amounts of fuel vapor. To ensure that the large amounts of fuel vapor generated during fuel tank filling and other conditions are not released into the atmosphere, several carbon-filled fuel vapor storage filters arranged in parallel can be selectively coupled to the heavy-duty vehicle's fuel tank. Parallel arrangement of carbon-filled fuel vapor storage filters allows carbon filters already in production to capture fuel vapors in systems that may generate even larger amounts of fuel vapor. This reduces system resources while allowing emissions standards to be met. Even so, parallel arrangement of carbon-filled fuel vapor storage filters presents other challenges. In particular, parallel arrangement of carbon-filled fuel vapor storage filters presents new challenges in ensuring that cracks or blockages in the hoses or conduits connecting the parallel filters together and to the fuel vapor control system can be detected. Summary of the Invention

[0003] The inventors of this paper have recognized the problems mentioned above and have developed a method for operating an evaporative emission system of a vehicle, the method comprising: operating a canister extraction valve and two canister vent valves arranged in parallel during a diagnostic sequence to diagnose the two canister vent valves and two canister vent lines connecting the two canister vent valves; and generating an indication of evaporative emission degradation in response to the output of a pressure sensor generated during the sequence.

[0004] By operating two filter canister vent valves and one filter canister extraction valve, it is possible to diagnose the presence or absence of deteriorated components using an evaporative exhaust system comprising parallel-arranged carbon-filled fuel vapor storage filter canisters. In particular, even if similar system components can be arranged in parallel, commanding valves to different open / close combinations allows for the assessment of individual valves and conduits or passages for cracks and / or jamming or blockage conditions.

[0005] This specification offers several advantages. In particular, the method provides an opportunity to diagnose components of a parallel-arranged evaporative emission system. Additionally, the method allows for the detection of potentially stuck valves and blocked pathways that may allow fluid communication between various components of the evaporative emission system. Furthermore, the method allows for the assessment of deterioration of individual evaporative system components.

[0006] The above and other advantages and features of this specification will become readily apparent when understood alone or in conjunction with the accompanying drawings, based on the following detailed description.

[0007] It is understood that the above description of the invention is provided to present a series of concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key features of the claimed subject matter, the scope of which is uniquely defined by the claims appended to the detailed embodiments. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0008] Figure 1 An example engine to which the evaporative emission system can be coupled is shown;

[0009] Figure 2 An example of a known evaporative emission system is shown;

[0010] Figure 3 An example evaporative emission system according to this disclosure is shown;

[0011] Figures 4 to 8 Example evaporative emission system pressures during the diagnostic sequence are shown;

[0012] Figure 9 A table is shown that identifies potential degradation modes in an evaporative emission system, including parallel-connected carbon-filled fuel vapor storage filter canisters; and

[0013] Figure 10 and Figure 11 An example method is shown for diagnosing the operation of an evaporative emission system that includes fuel vapor storage filters filled with carbon arranged in parallel. Detailed Implementation

[0014] The following description relates to systems and methods for operating vehicles and diagnosing evaporative emission systems. The vehicle may be a heavy-duty vehicle with a large fuel tank arranged in parallel and a carbon-filled fuel vapor storage filter. The vehicle may include... Figure 1 The type of engine shown in the image. Figure 2 A known evaporative emission system is shown in the figure. Figure 3 An example evaporative emission system according to this disclosure is shown. Figures 4 to 8 The system pressure during the evaporative emission diagnostic sequence is shown in the figure. Figure 9 The table shows the deterioration patterns of evaporative emission systems. Figure 10 and Figure 11 An example method for diagnosing the deterioration of an evaporative emission system comprising parallel-arranged carbon-filled filter canisters is shown.

[0015] refer to Figure 1 Internal combustion engine 10 (including multiple cylinders, Figure 1 One of the cylinders shown is controlled by an electronic engine controller 12. Controller 12... Figure 1 and Figure 3 The various sensors shown receive signals. The controller can employ... Figure 1 and Figure 3 The actuator shown adjusts the operation of the engine and evaporative emission system based on the received signals and instructions stored in the memory of the controller 12.

[0016] Engine 10 comprises a cylinder head 35 and a cylinder block 33, which includes a combustion chamber 30 and cylinder walls 32. A piston 36 is positioned therein and reciprocates via a connection to a crankshaft 40. The combustion chamber 30 is shown communicating with an intake manifold 44 and an exhaust manifold 48 via corresponding intake valves 52 and exhaust valves 54. Each intake and exhaust valve can be operated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 can be determined by an intake cam sensor 55. The position of the exhaust cam 53 can be determined by an exhaust cam sensor 57. The intake valve 52 can be selectively activated and deactivated by a valve activation device 59. The exhaust valve 54 can be selectively activated and deactivated by a valve actuation device 58. The intake and exhaust valves can be deactivated in a closed position so that they do not open during an engine cycle (e.g., four strokes). The valve actuation devices 58 and 59 can be electromechanical devices.

[0017] Fuel injector 66 is shown protruding into combustion chamber 30 and is positioned to inject fuel directly into cylinder 31, which is referred to by those skilled in the art as direct injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width from controller 12. Fuel is delivered to fuel injector 66 via a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). In one example, a high-pressure two-stage fuel system can be used to generate higher fuel pressure.

[0018] Additionally, intake manifold 44 is shown communicating with turbocharger compressor 162 and engine intake port 42. In other examples, compressor 162 may be a supercharger compressor. Shaft 161 mechanically connects turbocharger turbine 164 to turbocharger compressor 162. Optional electronic throttle 62 adjusts the position of throttle plate 64 to control airflow from compressor 162 to intake manifold 44. Since the inlet of throttle 62 is within boost chamber 45, the pressure in boost chamber 45 may be referred to as throttle inlet pressure. Throttle outlet is in intake manifold 44. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44, such that throttle 62 is an intake manifold throttle. Compressor recirculation valve 47 may be selectively adjustable to multiple positions between fully open and fully closed. The exhaust valve 163 can be adjusted via controller 12 to allow exhaust gas to selectively bypass turbine 164, thereby controlling the speed of compressor 162. Air filter 43 cleans the air entering engine intake 42.

[0019] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal exhaust oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, dual-state exhaust oxygen sensor may replace UEGO sensor 126.

[0020] In one example, converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each having multiple bricks, may be used. In one example, converter 70 may be a ternary catalyst.

[0021] Controller 12 in Figure 1The computer shown is a conventional microcomputer, which includes: a microprocessor unit 102, an input / output port 104, a read-only memory 106 (e.g., non-transitory memory), a random access memory 108, a keep-alive memory 110, and a conventional data bus. The controller 12 is shown to receive various signals from sensors coupled to the engine 10 in addition to those previously discussed, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; position sensor 134 coupled to driver demand pedal 130 to sense demand (e.g., torque or power) applied by human driver 132; position sensor 154 coupled to caliper pedal 150 to sense vehicle deceleration demand (e.g., torque) applied by human driver 132; engine manifold pressure (MAP) measurement from pressure sensor 122 coupled to intake manifold 44; engine position from engine position sensor 118 sensing crankshaft 40 position; air mass measurement from sensor 120 entering the engine; and throttle position measurement from sensor 68. Atmospheric pressure (sensor not shown) may also be sensed for processing by the controller 12. In a preferred aspect of this specification, engine position sensor 118 generates a predetermined number of equidistant pulses per crankshaft rotation, thereby determining engine speed (RPM).

[0022] The controller 12 can also receive input from the human / machine interface 11. A request to start the engine or vehicle can be generated by a human and input into the human / machine interface 11. The human / machine interface can be a touchscreen display, a button, a key switch, or other known device. The controller 12 can also automatically start the engine 10 in response to vehicle and engine operating conditions. Automatic engine starting can include starting the engine 10 without human input to a device (e.g., a key switch or button) dedicated solely to receiving input from a human for starting and / or stopping the rotation of the engine 10. For example, the engine 10 can automatically stop in response to a driver-demanded torque being less than a threshold and the vehicle speed being less than a threshold.

[0023] During operation, each cylinder within engine 10 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 54 is closed and the intake valve 52 is open. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its maximum volume) is generally referred to by those skilled in the art as bottom dead center (BDC).

[0024] During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its minimum volume) is commonly referred to by those skilled in the art as top dead center (TDC). Fuel is introduced into the combustion chamber during what is hereinafter referred to as injection. The injected fuel is ignited by a known ignition device, such as spark plug 92, resulting in combustion.

[0025] During the expansion stroke, the expanding gas pushes piston 36 back to the BDC. Crankshaft 40 converts the piston movement into rotational torque on the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture into exhaust manifold 48, and piston returns to the TDC. It should be noted that the above is merely illustrative, and the opening and / or closing timing of the intake and exhaust valves can vary, such as to provide positive or negative valve overlap, delayed intake valve closing, or various other examples.

[0026] Now for reference Figure 2 A block diagram of an example known evaporative emission system 200 is shown. The evaporative emission system 200 includes a canister extraction valve 202, a carbon-filled fuel vapor storage canister 204, a canister vent valve 206, a fuel tank pressure sensor 277, a fuel tank level sensor 276, a fuel tank cap 230, a fuel tank pressure control valve 212, a hydrocarbon sensor 275, and a fuel replenishment valve 214. In some examples, a leak detection module including a pump and a switching valve may replace the vent valve 206. The carbon-filled fuel vapor storage canister 204 may include activated carbon 211 to store fuel vapor. The fuel tank pressure control valve 212 and the fuel replenishment valve 214 are shown in fluid communication with the carbon-filled fuel vapor storage canister 204 and the fuel tank 220 via a conduit 233. Fuel can flow from the fuel tank cap 230 to the fuel tank 220 via a filler neck 231. The carbon-filled fuel vapor storage filter 204 can be selectively fluidly connected to the intake manifold 44 via a conduit 255 and a filter extraction valve 202.

[0027] During refilling of fuel tank 220, fuel supply valve 214 and filter canister vent valve 206 can be opened to allow fuel vapor to exit fuel tank 220, pass through duct 233, and be stored in carbon-filled fuel vapor storage filter canister 204. Hydrocarbon-free air can then flow from carbon-filled fuel vapor storage filter canister 204 to the atmosphere via duct or channel 256 and vent valve 206.

[0028] Fuel vapor can be extracted from the carbon-filled fuel vapor storage filter canister 204 by opening the filter canister extraction valve 202, completely closing the fuel tank pressure control valve 212, completely closing the fuel supply valve 214, and opening the filter canister vent valve 206. Specifically, when the filter canister extraction valve 202 and the filter canister vent valve are open, the low pressure in the engine intake manifold 44 can draw fuel vapor from the carbon-filled filter canister. Fresh air drawn in from the atmosphere may cause fuel vapor to desorb from the carbon-filled fuel vapor storage filter canister.

[0029] Now for reference Figure 3 A schematic diagram of a first example evaporative emission system 300 is shown. The evaporative emission system 300 can temporarily capture fuel vapor in one or more of carbon-filled fuel vapor storage filter tanks 302 and 304. The first carbon-filled fuel vapor storage filter tank 302 and the second carbon-filled fuel vapor storage filter tank 304 are arranged in parallel.

[0030] Fuel vapor 324 can be generated in the fuel tank via the sloshing of fuel 322 within the fuel tank and by filling the fuel tank 320 with fuel. Fuel vapor 324 in the fuel tank 320 can be released via a vapor shut-off valve 330 (VBV). A first load line 334 is a conduit or passage that directly fluidly connects the loading port L1 of the first carbon-filled fuel vapor storage filter 302 to a second load line 335 of the second carbon-filled fuel vapor storage filter 304. For example, there is no intermediate carbon-filled fuel vapor storage filter or valve to interfere with the fluid communication between the first load line 334 and the second load line 335. While the fuel vapor is being stored in the carbon-filled fuel vapor storage filter, it flows in the direction indicated by the solid arrow 352. Therefore, fuel vapor can flow simultaneously from the fuel tank 320 to both the first carbon-filled fuel vapor storage filter 302 and the second carbon-filled fuel vapor storage filter 304.

[0031] Ventilation line 336 is a conduit or channel that fluidly connects the first filter tank vent valve 310 directly to the second ventilation line 337 and exits from ventilation line 338. The first ventilation port V1 of the first carbon-filled fuel vapor storage filter tank 302 is directly connected to the first filter tank vent valve 310. Ventilation line 337 is also connected to the second ventilation valve 312. The second ventilation port V2 of the second carbon-filled fuel vapor storage filter tank 304 is directly connected to the second filter tank vent valve 312. The first filter tank vent valve 310 (e.g., CVV1) allows selective communication between the first ventilation port V1 and the first ventilation line 336. Similarly, the second filter tank vent valve 312 (e.g., CVV2) allows selective communication between the second ventilation port V2 and the second ventilation line 337. Therefore, the No. 1 filter tank ventilation valve 310 and the No. 2 filter tank ventilation valve 312 are arranged in parallel with each other because they are both connected to the No. 1 ventilation line 336 and connected to the outlet extraction line 313.

[0032] Fuel vapor 324 stored in a carbon-filled filter canister can be released into the engine 10 by opening the filter canister extraction valve 316. Figure 1 Fuel vapor is drawn from and combusted in the fuel vapor storage filter (shown in the diagram). A lower pressure (e.g., vacuum) in the intake manifold 44 allows fuel vapor to be drawn from both the first carbon-filled fuel vapor storage filter 302 (extraction port P1) and the second carbon-filled fuel vapor storage filter 304 (extraction port P2) simultaneously. Simultaneously, the first filter vent valve 310 and the second filter vent valve 312 can be opened, allowing fresh air to be drawn from the dust collection box 340 and into the first vent port V1 of the first carbon-filled fuel vapor storage filter 302 and the second vent port V2 of the second carbon-filled fuel vapor storage filter 304.

[0033] The filter canister extraction valve 316 (CPV) can be directly connected to the intake manifold 44 and exits the extraction line 313. The outlet extraction line 313 is also directly connected to extraction line 314 and extraction line 315. Extraction line 314 is also directly connected to extraction port P1. Extraction line 315 is also directly connected to extraction port P2. During fuel vapor extraction, the flow can be in the direction indicated by arrow 350.

[0034] Controller 12 controls the filter canister extraction valve 316, the vapor shut-off valve 330, the first filter canister vent valve 310, and the second filter canister vent valve 312. Additionally, controller 12 can sense the pressure within the system via fuel tank pressure sensor 388. Each of the carbon-filled fuel vapor storage filter canisters may include a buffer zone 362 and a filter 360. Filter 360 reduces the migration of carbon dust from the carbon-filled filter canister. Buffer zone 362 is an area within the filter canister that causes fuel vapor entering the loading port to immediately exit via the extraction port, thereby reducing the likelihood of large fuel vapor plumes being drawn into the engine.

[0035] therefore, Figure 1 and Figure 3The system provides an evaporative emission system, comprising: multiple carbon-filled fuel vapor storage filter tanks arranged in parallel; a fuel tank; a pressure sensor; a filter tank extraction valve; a first filter tank vent valve and a second filter tank vent valve; a first filter tank vent line directly connected to the first filter tank vent valve and directly connected to the second filter tank vent line, the second filter tank vent line also directly connected to the second filter tank vent valve, and the first filter tank vent line directly connected to the second filter tank vent line; a first filter tank load line directly connected to the first carbon-filled fuel vapor storage filter tanks. The system includes a gas storage filter canister, the first filter canister being directly connected to a second filter canister load line, the second filter canister load line being directly connected to a second carbon-filled fuel vapor storage filter canister included in the plurality of carbon-filled fuel vapor storage filter canisters; and a controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to perform an evaporative emission system diagnostic, the evaporative emission system diagnostic including a second phase in which the first filter canister vent valve is assessed as being in a normally open fault, the second filter canister vent valve is assessed as being in a normally open fault, the second filter canister vent valve is assessed as being in a normally closed fault, and the second filter canister vent line and the second filter canister load line are assessed as being blocked. In a first example, the evaporative emission system includes: wherein the phase is part of a plurality of phases in the evaporative emission system diagnostic, and wherein in each of the plurality of phases, at least one of the filter canister extraction valve, the first filter canister vent valve, and the second filter canister vent valve is adjusted to an operational state. In a second example that may include the first example, the evaporative emission system further includes additional executable instructions that cause the controller to compare a pressure indicated via the pressure sensor with a predetermined pressure or pressure range to evaluate the first and second filter canister vent valves. In a third example that may include one or both of the first and second examples, the evaporative emission system further includes additional executable instructions that cause the controller to perform a zero-stage diagnostic of the evaporative emission system, in which the filter canister extraction valve is evaluated as being in a normally closed fault. In a fourth example that may include one or more of the first to third examples, the evaporative emission system includes: wherein the filter canister extraction valve is evaluated based on the output of the pressure sensor. In a fifth example that may include one or more of the first to fourth examples, the evaporative emission system further includes additional executable instructions that cause the controller to perform a first stage diagnostic of the evaporative emission system, in which the first filter canister vent valve is evaluated as being in a normally closed fault.In a sixth example, which may include one or more of the first to fifth examples, the evaporative emission system further includes additional executable instructions that cause the controller to perform a third phase of diagnostics of the evaporative emission system, in which the evaporative emission system is assessed to have a crack.

[0036] Now for reference Figure 4 , showing according to Figure 10 and Figure 11 Example of a diagnostic sequence for stress using this method. Figure 10 and Figure 11 The method via Figure 1 and Figure 3 The system executes the sequence. In this example, there are five stages of the diagnostic sequence (e.g., stages zero through four), but in other examples, fewer or additional stages may be provided. The different stages attempt to isolate specific conditions that may indicate device deterioration, rupture, or alternatively, catheter blockage or occlusion. In this example, pressure indication occurs when the sequence is executed. Figure 10 and Figure 11 The method is the response of the evaporative emission system to operate as expected. Steam shut-off valves (e.g., Figure 3 330) was commanded to open and in Figure 4 The entire sequence shown in the figure is open during the entire process.

[0037] Graph 400 is a pressure versus time graph. The vertical axis represents pressure, and pressure increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. Line 402 represents the pressure in the fuel tank or near the vapor shut-off valve 330. Line 450 represents atmospheric pressure, and line 452 represents the target pressure at the end of the diagnostic sequence for a non-deteriorated evaporative emission system. The vertical lines from time t0 to t4 represent the relevant time of the diagnostic sequence.

[0038] The sequence and phase zero begin at time t0. The engine operates throughout the sequence (e.g., rotating and burning air and fuel) (not shown). During the sequence, the engine also generates a vacuum (not shown). At time t0, a command is given to open the first filter canister vent valve, a command is given to open the second filter canister vent valve, and a command is given to open the filter canister extraction valve. The valves operate as expected, and there are no breaks or blockages in the conduits providing fluid communication between the various system components. Therefore, the vacuum in the engine reduces the pressure in the system as observed via the fuel tank pressure sensor 388. A pressure drop occurs from the atmosphere across the first carbon-filled fuel vapor storage filter canister 302 and the second carbon-filled fuel vapor storage filter canister 304, causing the pressure in the fuel tank to reach the indicated pressure P1.

[0039] The sequence begins at time t1, when the No. 1 filter tank vent valve remains commanded open, the No. 2 filter tank vent valve is now commanded closed, and the filter tank extraction valve remains commanded open. Closing the No. 2 filter tank vent valve may cause the No. 2 load line and the No. 2 vent line to be considered blocked or simulate a normally closed fault in the No. 2 filter tank vent valve. This causes a further decrease in system pressure, resulting in a system pressure drop to pressure P2.

[0040] Phase two of this sequence begins at time t2, when the No. 1 filter tank vent valve is commanded to close, the No. 2 filter tank vent valve is commanded to open, and the filter tank extraction valve is commanded to open. Opening the No. 1 filter tank vent valve and closing the No. 2 filter tank vent valve may cause the No. 1 load line and the No. 1 vent line to be considered blocked or simulate a normally closed fault for the No. 1 filter tank vent valve. This allows the system pressure to be maintained substantially as it would be when the No. 1 filter tank vent valve is commanded to open and the No. 2 filter tank vent valve is commanded to close. Therefore, when the evaporative emission system operates as expected, the pressure in the system is now P3, which is within the predetermined pressure range of P2 (e.g., pressure P3 is at a certain percentage of P2). + (within 2%)

[0041] Phase three of the sequence begins at time t3, at which point the No. 1 filter canister vent valve is commanded to close, the No. 2 filter canister vent valve is commanded to close, and the filter canister extraction valve is commanded to open. Closing the No. 1 and No. 2 filter canister vent valves may cause the No. 1 load line, the No. 1 vent line, and the No. 2 vent line to be considered blocked, or to simulate a normally closed fault in both the No. 1 and No. 2 filter canister vent valves. This allows the system pressure to decrease further, bringing it close to the engine intake manifold pressure. Therefore, when the evaporative emission system is operating as expected, the system pressure is now reduced to pressure P4, which is within a predetermined pressure range of the current intake manifold pressure (MP) (e.g., P4 is within 10% of MP). Here, the system pressure reaches a threshold pressure 452, which, when combined with the results of phases 0 through 2, indicates that the evaporative emission system is operating as expected (e.g., there are no blockages or breaks at predetermined locations within the evaporative emission system). Therefore, the sequence proceeds to stage four, in which the filter canister extraction valve is commanded to close, the first filter canister vent valve is commanded to open, and the second filter canister vent valve is instructed to open. This allows the pressure in the evaporative emission system to approach atmospheric pressure on the fuel tank side of the filter canister extraction valve, as indicated by trace 402.

[0042] Therefore, as Figure 4 The pressure curves of the evaporative exhaust system shown can indicate an evaporative exhaust system that has not shown signs of degradation. The filter tank extraction valve, filter tank vent valve #1, and filter tank vent valve #2 of the evaporative exhaust system can be operated to determine... Figure 3 Whether the evaporative emission system shows signs of deterioration.

[0043] Now for reference Figure 5 , showing according to Figure 10 and Figure 11 Example of a diagnostic sequence for stress using this method. Figure 10 and Figure 11 The method via Figure 1 and Figure 3 The system executes the sequence. In this example, the pressure indicator is the first load line (e.g., Figure 1 Blockages in 334), No. 1 ventilation duct (e.g., Figure 1 Blockage in 336) or the No. 1 filter tank vent valve (e.g., Figure 1 310) is in a normally closed fault. Although Figure 10 and Figure 11 The method describes five stages, but stages zero and one are shown here because degradation is indicated before stage two is reached. Steam shut-off valves (e.g., Figure 3 330) was commanded to open and in Figure 5 The entire sequence shown in the figure is open during the entire process.

[0044] Graph 500 is a pressure versus time graph. The vertical axis represents pressure, and pressure increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. Line 502 represents the pressure in the fuel tank or near the vapor shut-off valve 330. Line 550 represents atmospheric pressure, and line 552 represents the target pressure at the end of the diagnostic sequence for a non-deteriorated evaporative emission system. The vertical lines at times t10 to t12 represent the relevant time of the diagnostic sequence.

[0045] The sequence and phase zero begin at time t10. The engine operates throughout the sequence (e.g., rotating and burning air and fuel) (not shown). The engine also generates a vacuum (not shown) throughout the sequence. At time t10, a command is given to open the first filter canister vent valve, a command is given to open the second filter canister vent valve, and a command is given to open the filter canister extraction valve. In this example, the pressure indicating a complete blockage of the first load line, a complete blockage of the first vent line, or a complete normally closed failure of the first filter canister vent valve is shown. Therefore, when a degradation occurs in the first load line, the first vent line, or the normally closed failure of the first filter canister vent valve, the vacuum in the engine will reduce the pressure in the system below pressure P1 or the expected pressure at the end of phase zero. A pressure drop occurs from the atmosphere across the single filter canister vent line (the second filter canister vent line), thereby restricting airflow from the dust collection box (e.g., Figure 3(340) enters the evaporative emission control system. Because the individual filter canister vent line operates as a confined air path rather than the more free-flowing parallel filter canister vent lines, the system pressure measured near the fuel tank decreases to pressure P1', which is less than pressure P1 due to the confinement of the individually operated filter canister vent line (filter canister vent line number two).

[0046] The sequence begins at time t11, when the No. 1 filter canister vent valve remains commanded open, the No. 2 filter canister vent valve is now commanded closed, and the filter canister extraction valve remains commanded open. Closing the No. 2 filter canister vent valve may cause the airflow into the evaporative emission system to approach zero, because in this example, the No. 1 load line, the No. 1 vent line, or the No. 1 filter canister vent valve is degraded. A degraded No. 1 load line, a degraded No. 1 vent line, or a No. 1 filter canister vent valve in a completely closed state restricts airflow into the evaporative emission system, preventing airflow through the first carbon-filled fuel vapor storage filter canister 302. Therefore, the pressure in the evaporative emission system near the fuel tank further decreases towards the engine intake manifold pressure. The pressure in the fuel system at the fuel tank reaches line 552 and the target pressure. Therefore, the sequence reaches the target pressure before the end of phase three. This indicates that the No. 1 load line or the No. 1 vent line may be blocked, or alternatively, the No. 1 filter canister vent valve may be stuck in a fully closed state instead of reaching the currently commanded open position. Therefore, if the system pressure in the evaporative emission system follows Figure 5 The curve shown indicates that the No. 1 load line or the No. 1 ventilation line may be blocked, or alternatively, the No. 1 filter tank ventilation valve may be stuck in a completely closed state.

[0047] Now for reference Figure 6 , showing according to Figure 10 and Figure 11 Example of a diagnostic sequence for stress using this method. Figure 10 and Figure 11 The method via Figure 1 and Figure 3 The system executes the sequence. In this example, the pressure indicator is the second load line (e.g., Figure 1 The blockage in 335), the second ventilation duct (e.g., Figure 1 Blockage in 337) or the second filter tank vent valve (e.g., Figure 1 312) is in a normally closed fault. Although Figure 10 and Figure 11 The method describes five stages, but stages zero to two are shown here because degradation is indicated before stage three is reached. Steam shut-off valves (e.g., Figure 3 330) was commanded to open and in Figure 6 The entire sequence shown in the figure is open during the entire process.

[0048] Graph 600 is a pressure versus time graph. The vertical axis represents pressure, and pressure increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. Line 602 represents the pressure in the fuel tank or near the vapor shut-off valve 330. Line 650 represents atmospheric pressure, and line 652 represents the target pressure at the end of the diagnostic sequence for a non-deteriorated evaporative emission system. The vertical lines at times t20 to t23 represent the relevant time of the diagnostic sequence.

[0049] The sequence and phase zero begin at time t20. The engine operates throughout the sequence (e.g., rotating and burning air and fuel) (not shown). The engine also generates a vacuum (not shown) throughout the sequence. At time t20, a command is given to open the No. 1 filter canister vent valve, a command is given to open the No. 2 filter canister vent valve, and a command is given to open the filter canister extraction valve. In this example, the pressure indicating a complete blockage of the No. 2 load line, a complete blockage of the No. 2 vent line, or a No. 2 filter canister vent valve in a completely closed state is shown. Therefore, when a deterioration occurs in the No. 2 load line, the No. 2 vent line, or the No. 2 filter canister vent valve in a normally closed state, the vacuum in the engine will reduce the pressure in the system below pressure P1 or the expected pressure at the end of phase zero. A pressure drop occurs from the atmosphere across the individual filter canister vent line (the No. 1 filter canister vent line), thereby restricting airflow from the dust collection box (e.g., Figure 3 (340) enters the evaporative emission control system. Because the individual filter canister vent line operates as a confined air path rather than the more free-flowing parallel filter canister vent lines, the system pressure measured near the fuel tank decreases to pressure P1', which is less than pressure P1 due to the confinement of the individually operated filter canister vent line (filter canister vent line 1).

[0050] The sequence begins at time t21, at which point the No. 1 filter canister vent valve remains commanded open, the No. 2 filter canister vent valve is now commanded closed, and the filter canister extraction valve remains commanded open. Closing the No. 2 filter canister vent valve does not cause much (if any) change in airflow into the evaporative emission system because, in this example, the No. 2 load line, the No. 2 vent line, or the No. 2 filter canister vent valve is degraded. The degraded No. 2 load line, the degraded No. 2 vent line, or the No. 2 filter canister vent valve in a state of complete normally closed failure already constrain the airflow into the evaporative emission system; therefore, closing the No. 2 filter canister vent valve does not generate a pressure change within the evaporative emission system. Thus, the pressure in the evaporative emission system near the fuel tank remains essentially constant (e.g., the change is less than 5% of the reading). The pressure in the fuel system at the fuel tank reaches pressure P2.

[0051] Phase two of the sequence begins at time t22, when the No. 1 filter canister vent valve is commanded to close, the No. 2 filter canister vent valve is now commanded to open, and the filter canister extraction valve remains commanded to open. Closing the No. 1 filter canister vent valve may cause the airflow into the evaporative emission system to approach zero because, in this example, the No. 2 load line, the No. 2 vent line, or the No. 2 filter canister vent valve is degraded (in a completely closed fault). The degraded No. 2 load line, the degraded No. 2 vent line, or the No. 2 filter canister vent valve in a completely closed fault restricts airflow into the evaporative emission system, preventing airflow through the second carbon-filled fuel vapor storage filter canister 304. Consequently, the pressure in the evaporative emission system near the fuel tank further decreases towards the engine intake manifold pressure. The pressure in the fuel system at the fuel tank reaches line 652 and the target pressure. Therefore, the sequence reaches the target pressure before the end of phase three. This indicates that the No. 1 load line or the No. 2 vent line may be blocked, or alternatively, the No. 2 filter canister vent valve may be stuck in a completely closed position instead of reaching the currently commanded open position. Therefore, if the system pressure in the evaporative emission system follows Figure 6 The curve shown indicates that the No. 2 load line or the No. 2 ventilation line may be blocked, or alternatively, the No. 2 filter tank ventilation valve may be stuck in a fully closed state.

[0052] Now for reference Figure 7 , showing according to Figure 10 and Figure 11 Example of a diagnostic sequence for stress using this method. Figure 10 and Figure 11 The method via Figure 1 and Figure 3 The system executes the sequence. In this example, the pressure indicator for the first filter tank vent valve (e.g., Figure 1 310) is in a normally open fault state. Although Figure 10 and Figure 11 The method describes five stages, but stages zero to two are shown here because degradation is indicated before stage three is reached. Steam shut-off valves (e.g., Figure 3 330) was commanded to open and in Figure 6 The entire sequence shown in the figure is open during the entire process.

[0053] Graph 700 is a pressure versus time graph. The vertical axis represents pressure, and pressure increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. Line 702 represents the pressure in the fuel tank or near the vapor shut-off valve 330. Line 750 represents atmospheric pressure, and line 752 represents the target pressure at the end of the diagnostic sequence for a non-deteriorated evaporative emission system. The vertical lines from time t30 to t33 represent the relevant time of the diagnostic sequence.

[0054] The sequence and phase zero begin at time t30. The engine operates throughout the sequence (e.g., rotating and burning air and fuel) (not shown). The engine also generates a vacuum (not shown) throughout the sequence. At time t30, a command is given to open canister vent valve #1, a command is given to open canister vent valve #2, and a command is given to open canister extraction valve. In this example, the pressure indicating that canister vent valve #1 is in a fully open fault is shown. Therefore, when canister vent valve #1 is in a normally open fault, the vacuum in the engine reduces the pressure in the system to pressure P1, or the expected pressure at the end of phase zero. A pressure drop occurs from the atmosphere across the two canister vent lines (canister vent line #1 and canister vent line #2). Therefore, there is no pressure difference from the non-deteriorated system in phase zero of the diagnostic sequence.

[0055] The sequence begins at time t31, at which point the No. 1 filter tank vent valve remains commanded open, the No. 2 filter tank vent valve is now commanded closed, and the filter tank extraction valve remains commanded open. Closing the No. 2 filter tank vent valve restricts airflow into the evaporative emission system. Therefore, the system pressure drops to P2 in the same manner as the pressure drop to P2 in the undeteriorated evaporative emission system during diagnostics.

[0056] Phase two of the sequence begins at time t32, at which point the No. 1 filter canister vent valve is commanded to close, the No. 2 filter canister vent valve is now commanded to open, and the filter canister extraction valve remains commanded to open. Opening the No. 2 filter canister vent valve, while the No. 1 filter canister vent valve is in a normally open fault position, increases the airflow into the evaporative emission system, thus increasing the pressure in the evaporative emission system. This increase in airflow results in two open flow paths now existing between the atmosphere and the fuel tank. Therefore, the system pressure increases from pressure P2 to pressure P3”', as indicated by line 702. This indicates that the No. 1 filter canister vent valve is in a fully open fault position. Therefore, if the system pressure in the evaporative emission system follows Figure 7 The curve shown in the figure indicates that the ventilation valve of filter tank No. 1 is in a normally open fault.

[0057] Now for reference Figure 8 , showing according to Figure 10 and Figure 11 Example of a diagnostic sequence for stress using this method. Figure 10 and Figure 11 The method via Figure 1 and Figure 3 The system executes the sequence. In this example, the pressure is indicated by the second filter tank vent valve (e.g., Figure 1 312) is in a normally open fault state. Although Figure 10 and Figure 11 The method describes five stages, but stages zero to two are shown here because degradation is indicated before stage three is reached. Steam shut-off valves (e.g., Figure 3330) was commanded to open and in Figure 6 The entire sequence shown in the figure is open during the entire process.

[0058] Graph 800 is a pressure versus time graph. The vertical axis represents pressure, and pressure increases in the direction of the arrow on the vertical axis. The horizontal axis represents time, and time increases from the left to the right of the graph. Line 802 represents the pressure in the fuel tank or near the vapor shut-off valve 330. Line 850 represents atmospheric pressure, and line 852 represents the target pressure at the end of the diagnostic sequence for a non-deteriorated evaporative emission system. The vertical lines at times t40 to t43 represent the relevant time of the diagnostic sequence.

[0059] The sequence and phase zero begin at time t40. The engine operates throughout the sequence (e.g., rotating and burning air and fuel) (not shown). The engine also generates a vacuum (not shown) throughout the sequence. At time t40, a command is given to open the first filter canister vent valve, a command is given to open the second filter canister vent valve, and a command is given to open the filter canister extraction valve. In this example, the pressure indicating that the second filter canister vent valve is in a fully open fault is shown. Therefore, when the second filter canister vent valve is in a normally open fault, the vacuum in the engine reduces the pressure in the system to pressure P1, or the expected pressure at the end of phase zero. A pressure drop occurs from the atmosphere across the two filter canister vent lines (the first and second filter canister vent lines). Therefore, there is no pressure difference from the non-deteriorated system in phase zero of the diagnostic sequence.

[0060] The sequence begins at time t41, at which point the vent valve for filter tank 1 remains commanded open, the vent valve for filter tank 2 is now commanded closed, and the filter tank extraction valve remains commanded open. Commanding the vent valve for filter tank 2 to close has no effect on the system pressure because the vent valve for filter tank 2 is in a fully open fault state. Therefore, the airflow into the evaporative emission system is no longer restricted, and the system pressure moves from P1 to P2", where pressure P2"" can be lower than that of P1. + Within 2%. However, there is currently insufficient pressure data to indicate deterioration of the No. 2 filter tank vent valve. Therefore, the sequence continues to stage two.

[0061] Phase two of the sequence begins at time t42, at which point the No. 1 filter canister vent valve is commanded to close, the No. 2 filter canister vent valve is now commanded to open, and the filter canister extraction valve remains commanded to open. Closing the No. 1 filter canister vent valve when the No. 2 filter canister vent valve is in a normally open fault position reduces the airflow into the evaporative emission system, thus lowering the pressure in the evaporative emission system. This reduction in airflow results in a single open flow path between the atmosphere and the fuel tank. Consequently, the system pressure decreases from pressure P2"" to pressure P3"', as indicated by line 802. This indicates that the No. 2 filter canister vent valve is in a fully open fault position. Therefore, if the system pressure in the evaporative emission system follows... Figure 8 The curve shown in the figure indicates that the ventilation valve of filter tank No. 1 is in a normally open fault.

[0062] Turn now Figure 9 Table 900 illustrates one method for determining the degradation of an evaporative emission system comprising two carbon-filled fuel vapor storage filter tanks. Table 900 comprises eight rows 902 and three columns 904. The first row from the top of Table 900 and the first column from the left of Table 900 describe “Stages” to indicate the stages of the evaporative emission diagnostic sequence. The first row from the top of Table 900 and the second column from the left of Table 900 describe “Pressure Difference” to indicate the differential pressure in the evaporative emission system relative to atmospheric pressure. The third row from the top of Table 900 and the first column from the left of Table 900 describe “Degradation Mode” to indicate whether the evaporative system is degraded, and if so, which evaporative emission system component is degraded. Rows 2 through 8 from the top of Table 900 and column 1 from the left of Table 900 indicate stages of the evaporative emission system sequence in which the evaporative emission system is indicated as degraded or not degraded. Rows 2 through 8 from the top of Table 900 and column 2 from the left of Table 900 indicate the system pressure range, which indicates the degradation of the evaporative emission system. Rows 2 through 8 from the top of Table 900 and column 3 from the left of Table 900 indicate the degradation mode of the evaporative emission system. The values ​​in the second column from the left of Table 900 can be adjusted according to the application, the amount of carbon-filled fuel vapor stored, and other system conditions.

[0063] Table 900 can serve as a basis for determining whether an evaporative emission system has deteriorated. For example, if the following is implemented... Figures 4 to 8The sequence shown indicates that, in the first stage of evaporative emission system diagnostics, when the pressure difference between atmospheric pressure and the evaporative emission system pressure (e.g., the pressure at the location of the pressure sensor in the evaporative emission system) is substantially zero, a normally closed filter canister extraction valve (CPV) can be identified as faulty. When the pressure difference between atmospheric pressure and evaporative emission system pressure is less than -6 inches of water column in stage one of the evaporative emission diagnostics (dP1), it may indicate that the No. 1 carbon canister vent valve (CVV1) is normally closed, the No. 1 vent line is blocked, or the No. 1 load line is blocked. When the pressure difference between atmospheric pressure and evaporative emission system pressure is less than -0.5 inches of water column in stage one of the evaporative emission diagnostics (dP1) and the evaporative emission system pressure is greater than 0.25 inches of water column in stage two of the evaporative emission diagnostics (dP2), it may indicate that the No. 1 filter canister vent valve (CVV1) is normally open. When the pressure difference between atmospheric pressure and evaporative emission system pressure in Phase 1 of the evaporative emission diagnostic (dP1) is greater than -1.25 inches of water column and the evaporative emission system pressure in Phase 2 of the evaporative emission diagnostic (dP2) is less than -0.25 inches of water column, it may indicate that the No. 2 filter canister vent valve (CVV2) is normally open. When the pressure difference between atmospheric pressure and evaporative emission system pressure in Phase 2 of the evaporative emission diagnostic (dP2) is less than -6 inches of water column, it may indicate that the No. 2 carbon canister vent valve (CVV2) is normally closed, the No. 2 vent line is blocked, or the No. 2 load line is blocked. When the pressure difference between atmospheric pressure and evaporative emission system pressure in Phase 3 of the evaporative emission diagnostic (dP3) is less than -6 inches of water column, it may indicate no evaporative emission system degradation. When the pressure difference between atmospheric pressure and evaporative emission system pressure in Phase 3 of the evaporative emission diagnostic (dP1) is less than -3 inches of water column but greater than -6 inches of water column, it may indicate a crack in the evaporative emission system.

[0064] Now for reference Figure 10 and Figure 11 An example method 1000 for diagnosing diagnostic operations of an evaporative emission system is shown. At least a portion of method 1000 can be included as executable instructions stored in a non-transitory memory, such as... Figure 1 and Figure 3 In the system shown, and in cooperation with the system described. When Figure 10 and Figure 11 When the method is implemented as executable instructions stored in the controller memory, the method causes the controller to actuate actuators in the real world and receive data and signals from the sensors described herein. Method 1000 can be performed while the vehicle's engine is operating under predetermined conditions in which a vacuum greater than a threshold amount can be generated within the engine's intake manifold. During the execution of method 1000, the engine may or may not rotate and burn fuel.

[0065] At point 1002, method 1000 determines whether to diagnose the parallel-arranged evaporative emission system and its carbon-filled fuel vapor storage filter. In one example, method 1000 may choose to diagnose the evaporative emission system after predetermined conditions have been met. Predetermined conditions may include, but are not limited to: the amount of time since the last most recent evaporative emission system diagnosis exceeding a threshold amount of time, a predetermined actual total number of recent engine starts exceeding a threshold, the carbon-filled fuel vapor filter being filled with fuel vapor, and / or a manual request to diagnose the evaporative emission system. If method 1000 determines that the diagnosis has been met, it includes conditions such as... Figure 3 If the conditions of the evaporative emission system of the parallel-arranged carbon-filled fuel vapor storage filter tanks shown are met, then the answer is yes, and method 1000 proceeds to 1004. Otherwise, the answer is no, and method 1000 proceeds to exit.

[0066] At point 1004, method 1000 enters stage zero of the evaporative emission system diagnostics, in which method 1000 commands the filter tank extraction valve to fully open, commands the first filter tank vent valve to fully open, and commands the second filter tank vent valve to fully open. Method 1000 may remain at stage zero for a predetermined amount of time or until a specific condition is met. For example, method 1000 may remain at stage zero for 10 seconds, or until the evaporative emission system pressure stabilizes within a specified pressure range. Method 1000 proceeds to point 1006.

[0067] At 1006, method 1000 determines whether the evaporative emission system condition during stage zero indicates evaporative emission system deterioration. If yes, the answer is yes, and method 1000 proceeds to 1030. Otherwise, the answer is no, and method 1000 proceeds to 1008. In one example, method 1000 may determine that the condition during stage zero of the current evaporative emission system diagnosis indicates deterioration when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., the pressure at the location of a pressure sensor within the evaporative emission system) is substantially zero (e.g., less than a 1-inch column of water pressure difference).

[0068] At 1030, Method 1000 indicates that the filter canister extraction valve (CPV) is in a normally closed fault. Method 1000 can indicate that the filter canister extraction valve is stuck by displaying a message at the human / machine interface 11. Method 1000 proceeds to 1032.

[0069] At point 1032, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 may attempt to cycle the filter canister extraction valve several times by commanding it to open and close several times. If the filter canister extraction valve does not open, method 1000 may take additional actions, such as opening filter canister vent valve 1, filter canister vent valve 2, and vapor shut-off valve to constrain the fuel tank pressure when the pressure in the fuel tank exceeds a threshold pressure. Method 1000 then proceeds to exit.

[0070] At point 1008, method 1000 enters stage one of the evaporative emission system diagnostics, in which method 1000 commands the filter tank extraction valve to fully open, commands the first filter tank vent valve to fully open, and commands the second filter tank vent valve to fully close. Method 1000 may remain in stage one for a predetermined amount of time or until a specific condition is met. For example, method 1000 may remain in stage zero for 10 seconds, or until the evaporative emission system pressure stabilizes within a specified pressure range. Method 1000 proceeds to point 1010.

[0071] At 1010, method 1000 determines whether the evaporative emission system condition during Phase 1 indicates evaporative emission system deterioration. If yes, the answer is yes, and method 1000 proceeds to 1040. Otherwise, the answer is no, and method 1000 proceeds to 1012. In one example, method 1000 may determine that the condition during Phase 1 of the current evaporative emission system diagnostic indicates deterioration when the pressure difference between atmospheric pressure and the evaporative emission system pressure (e.g., the pressure at the location of the pressure sensor within the evaporative emission system) is less than a predetermined pressure (i.e., -6 inches of water column or 1.49 kPa).

[0072] At 1040, method 1000 indicates that the No. 1 filter tank vent valve (CVV1) is in a normally closed fault, the No. 1 ventilation line is blocked, or the No. 1 load line is blocked. Method 1000 can indicate this by displaying a message at the human / machine interface 11. Method 1000 proceeds to 1042.

[0073] At point 1042, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 may attempt to cycle the No. 1 filter canister vent valve several times by commanding it to open and close several times. If the No. 1 filter canister vent valve does not open, method 1000 may take additional actions, such as increasing the opening time of the filter canister extraction valve during fuel vapor extraction and / or increasing the extraction vapor extraction duration to compensate for the lower flow rate through the evaporative emission system. Method 1000 then proceeds to exit.

[0074] At point 1012, method 1000 enters stage two of the evaporative emission system diagnostics, in which method 1000 commands the filter canister extraction valve to fully open, commands the first filter canister vent valve to fully close, and commands the second filter canister vent valve to fully open. Method 1000 may remain in stage two for a predetermined amount of time or until a specific condition is met. For example, method 1000 may remain in stage two for 10 seconds, or until the evaporative emission system pressure stabilizes within a specified pressure range (e.g., a target vacuum level). Method 1000 proceeds to point 1014.

[0075] At 1014, method 1000 determines whether a first evaporative emission system condition indicating evaporative emission system degradation exists during Phase Two of the evaporative emission system diagnostic sequence. If yes, the answer is yes, and method 1000 proceeds to 1050. Otherwise, the answer is no, and method 1000 proceeds to 1016. In one example, method 1000 may determine that a first condition during Phase Two of the current evaporative emission system diagnostic indicates that degradation may have occurred when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., the pressure at the location of a pressure sensor within the evaporative emission system) is less than a predetermined pressure (e.g., less than -6 inches of water column or 1.49 kPa).

[0076] At 1050, method 1000 indicates that the second filter tank vent valve (CVV2) is in a normally closed fault, the first ventilation line is blocked, or the first load line is blocked. Method 1000 can indicate this by displaying a message at the human / machine interface 11. Method 1000 proceeds to 1052.

[0077] At point 1052, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 may attempt to cycle the second filter canister vent valve several times by commanding it to open and close several times. If the second filter canister vent valve does not open, method 1000 may take additional actions, such as increasing the opening time of the filter canister extraction valve during fuel vapor extraction and / or increasing the extraction vapor extraction duration to compensate for the lower flow rate through the evaporative emission system. Method 1000 proceeds to exit.

[0078] At 1016, method 1000 determines whether a second evaporative emission system condition indicating deterioration of the evaporative emission system exists during phase two of the evaporative emission system diagnostic sequence. If yes, the answer is yes, and method 1000 proceeds to 1060. Otherwise, the answer is no, and method 1000 proceeds to 1018. In one example, during the first phase of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., the pressure at the location of a pressure sensor within the evaporative emission system) is less than a predetermined pressure (e.g., -0.5 inches of water), and during the second phase of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure is greater than a predetermined pressure (e.g., 0.25 inches of water), method 1000 can determine that a second condition indicating deterioration exists during phase two of the current evaporative emission system diagnostic.

[0079] At 1060, method 1000 indicates that the No. 1 filter tank vent valve (CVV1) is in a normally open fault. Method 1000 can indicate that the No. 1 filter tank vent valve (CVV1) is in a normally open fault by displaying a message at human / machine interface 11. Method 1000 proceeds to 1062.

[0080] At point 1062, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 may attempt to cycle the No. 1 filter canister vent valve several times by commanding it to open and close several times. If the No. 1 filter canister vent valve does not open, method 1000 may take additional actions, such as increasing the opening time of the filter canister extraction valve during fuel vapor extraction and / or increasing the extraction vapor extraction duration to compensate for the lower flow rate through the evaporative emission system. Method 1000 proceeds to exit.

[0081] At 1018, method 1000 determines whether a third evaporative emission system condition indicating evaporative emission system deterioration exists during phase two of the evaporative emission system diagnostic sequence. If yes, the answer is yes, and method 1000 proceeds to 1060. Otherwise, the answer is no, and method 1000 proceeds to 1020. In one example, during the first phase of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., the pressure at the location of a pressure sensor within the evaporative emission system) is greater than a predetermined pressure (e.g., -1.25 inches of water column), and during the second phase of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure is less than a predetermined pressure (e.g., -0.25 inches of water column), method 1000 can determine that a third evaporative emission system condition indicating evaporative emission system deterioration exists during phase two of the current evaporative emission system diagnostic.

[0082] At 1070, Method 1000 indicates that the second filter tank vent valve (CVV2) is in a normally open fault. Method 1000 can indicate that the second filter tank vent valve (CVV2) is in a normally open fault by displaying a message at the human / machine interface 11. Method 1000 proceeds to 1072.

[0083] At point 1072, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 may attempt to cycle the second filter canister vent valve several times by commanding it to open and close several times. If the second filter canister vent valve does not open, method 1000 may take additional actions, such as increasing the opening time of the filter canister extraction valve during fuel vapor extraction and / or increasing the extraction vapor extraction duration to compensate for the lower flow rate through the evaporative emission system. Method 1000 then proceeds to exit.

[0084] At point 1020, method 1000 enters stage three of the evaporative emission system diagnostics, in which method 1000 commands the filter canister extraction valve to fully open, the first filter canister vent valve to fully close, and the second filter canister vent valve to fully close. Method 1000 may remain in stage three for a predetermined amount of time or until a specific condition is met. For example, method 1000 may remain in stage three for 10 seconds, or until the evaporative emission system pressure stabilizes within a specified pressure range (e.g., a target vacuum level). Method 1000 proceeds to point 1022.

[0085] At 1022, method 1000 determines whether a first evaporative emission system condition indicating deterioration of the evaporative emission system exists during phase three of the evaporative emission system diagnostic sequence. If yes, the answer is yes, and method 1000 proceeds to 1080. Otherwise, the answer is no, and method 1000 proceeds to 1024. In one example, during phase three of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., pressure at the location of a pressure sensor within the evaporative emission system) is greater than a first predetermined pressure (e.g., -3 inches of water column), and when the pressure difference between atmospheric pressure and evaporative emission system pressure is greater than a predetermined pressure (e.g., -6 inches of water column), method 1000 can determine that the first condition during phase three of the current evaporative emission system diagnostic indicates a crack in the evaporative emission system.

[0086] At 1080, method 1000 indicates that a crack exists in the evaporative emission system, the second filter tank vent valve (CVV2) is in a normally closed fault, the first vent line is blocked (e.g., blocked to the point that flow is prevented from passing through the line), or the first load line is blocked. Method 1000 can indicate the presence of a crack in the evaporative emission system by displaying a message at human / machine interface 11. Method 1000 proceeds to 1082.

[0087] At point 1082, method 1000 performs mitigation actions based on the deterioration of the evaporative emission system. In one example, method 1000 can stop operating the filter tank extraction valve, filter tank vent valve 1, and filter tank vent valve 2 by commanding them to close. Method 1000 then proceeds to exit.

[0088] At 1024, method 1000 determines whether a second evaporative emission system condition indicating deterioration of the evaporative emission system exists during phase three of the evaporative emission system diagnostic sequence. If yes, the answer is yes, and method 1000 proceeds to 1080. Otherwise, the answer is no, and method 1000 proceeds to 1026. In one example, during phase three of the evaporative emission system diagnostic sequence, when the pressure difference between atmospheric pressure and evaporative emission system pressure (e.g., pressure at the location of a pressure sensor within the evaporative emission system) is less than a predetermined pressure (e.g., -6 inches of water column), method 1000 may determine that the second condition during phase three of the current evaporative emission system diagnostic indicates a crack in the evaporative emission system.

[0089] At 1090, method 1000 indicates via human / machine interface that the evaporative emission system is operating as expected and exits.

[0090] At point 1026, method 1000 can re-initiate the current evaporative emission system diagnostics. Method 1000 can also indicate that the current evaporative emission system diagnostic sequence has not been executed as expected. Method 1000 proceeds to exit.

[0091] In this way, method 1000 can perform diagnostics on components of the evaporative emission system, including but not limited to conduits or pipes between various components, filter canister vent valves, filter canister extraction valves, and fuel tanks. Method 1000 is performed in the order that allows method 1000 to diagnose the individual components of the evaporative emission system.

[0092] therefore, Figure 10 and Figure 11The method provides a method for operating an evaporative emission system of a vehicle, the method comprising: operating a canister extraction valve and two canister vent valves arranged in parallel during a diagnostic sequence to diagnose the two canister vent valves and two canister vent lines connecting the two canister vent valves; and generating an indication of evaporative emission degradation in response to an output of a pressure sensor generated during the sequence. In a first example, the method includes wherein the two canister vent valves are connected to an outlet vent line. In a second example that may include the first example, the method includes wherein a first of the two canister vent valves is connected to a first carbon-filled fuel vapor storage canister, and wherein a second of the two canister vent valves is connected to a second carbon-filled fuel vapor storage canister. In a third example that may include one or both of the first and second examples, the method includes wherein the operation includes commanding the canister extraction valve and the two canister vent valves to be fully opened and fully closed. In a fourth example that may include one or more of the first to third examples, the method further includes operating the canister extraction valve and the two canister vent valves in a plurality of diagnostic sequence stages, wherein the duration of each of the plurality of diagnostic sequence stages is time-based. In a fifth example, which may include one or more of the first to fourth examples, the method further includes monitoring the output of a pressure sensor during each of the plurality of diagnostic sequence stages. In a sixth example, which may include one or more of the first to fifth examples, the method further includes comparing a pressure determined based on the output of the pressure sensor with a predetermined pressure in each of the plurality of diagnostic sequence stages. In a seventh example, which may include one or more of the first to sixth examples, the method includes comparing the output of the pressure sensor with a plurality of pressure ranges during a second stage of the plurality of diagnostic sequence stages.

[0093] Figure 10 and Figure 11The method also provides a method for operating an evaporative emission system of a vehicle, the method comprising: commanding the opening of a first filter canister vent valve, a second filter canister vent valve, and a filter canister extraction valve during an initial phase of evaporative emission system diagnostics, wherein the first filter canister vent valve and the second filter canister vent valve are arranged in parallel; commanding the closing of the second filter canister vent valve and commanding the opening of the first filter canister vent valve and the filter canister extraction valve during a first phase of evaporative emission system diagnostics; commanding the closing of the first filter canister vent valve and commanding the opening of the second filter canister vent valve and the filter canister extraction valve during a second phase of evaporative emission system diagnostics; and commanding the closing of the first filter canister vent valve and the second filter canister vent valve and commanding the opening of the filter canister extraction valve during a third phase of evaporative emission system diagnostics. In a first example, the method further comprises generating an indication of evaporative emission degradation in response to a pressure sensor output being outside a threshold range during the initial phase of evaporative emission system diagnostics. In a second example that may include the first example, the method further comprises generating an indication of evaporative emission degradation in response to the pressure sensor output being outside a second threshold range during the first phase of evaporative emission system diagnostics. In a third example that may include one or both of the first and second examples, the method further includes generating an indication of evaporative emission degradation in response to the pressure sensor output being outside a third threshold range during the second phase of the evaporative emission system diagnostics. In a fourth example that may include one or more of the first to third examples, the method further includes generating an indication of evaporative emission degradation in response to the pressure sensor output being outside a fourth threshold range during the third phase of the evaporative emission system diagnostics.

[0094] It should be noted that the example control and estimation routines included herein can be used with various engine and / or vehicle system configurations. Furthermore, 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 programs disclosed herein can be stored as executable instructions in non-transitory memory and can be executed 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, multitasking, multithreading, etc. For this purpose, the various actions, operations, and / or functions shown may be executed in the order shown, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily necessary to achieve the features and advantages of the example 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 according to the specific strategy used. Furthermore, the actions, operations, and / or functions can be graphically represented as code 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 conjunction with an electronic controller in a system including various engine hardware components.

[0095] This specification concludes here. Many variations and modifications will arise in those skilled in the art upon reading this specification without departing from its spirit and scope. For example, this specification may be beneficial to I3, I4, I5, V6, V8, V10, and V12 engines operating with natural gas, gasoline, diesel, or alternative fuels.

[0096] The appended claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may refer to a "one" element or a "first" element or its equivalent. Such claims are to be understood as including a combination 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 amending these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

[0097] According to the present invention, a method for operating an evaporative emission system of a vehicle includes: operating a canister extraction valve and two canister vent valves arranged in parallel during a diagnostic sequence to diagnose the two canister vent valves and two canister vent lines connecting the two canister vent valves; and generating an indication of evaporative emission degradation in response to the output of a pressure sensor generated during the diagnostic sequence.

[0098] In one aspect of the invention, the two filter canister ventilation valves are connected to the outlet ventilation duct.

[0099] In one aspect of the invention, a first of the two filter canister vent valves is connected to a first carbon-filled fuel vapor storage filter canister, and a second of the two filter canister vent valves is connected to a second carbon-filled fuel vapor storage filter canister.

[0100] In one aspect of the invention, the operation includes commanding the complete opening and complete closing of the filter canister extraction valve and the two filter canister vent valves.

[0101] In one aspect of the invention, the method includes operating the filter canister extraction valve and the two filter canister vent valves in a plurality of diagnostic sequence stages, wherein the duration of each of the plurality of diagnostic sequence stages is time-based.

[0102] In one aspect of the invention, the method includes monitoring the output of a pressure sensor during each of a plurality of diagnostic sequence stages.

[0103] In one aspect of the invention, the method includes comparing a pressure determined based on the output of a pressure sensor with a predetermined pressure in each of the plurality of diagnostic sequence stages.

[0104] In one aspect of the invention, during the second phase of the plurality of diagnostic sequence phases, the output of the pressure sensor is compared with a plurality of pressure ranges.

[0105] According to the present invention, an evaporative emission system is provided, comprising: a first carbon-filled fuel vapor storage filter canister, wherein the first carbon-filled fuel vapor storage filter canister and a second carbon-filled fuel vapor storage filter canister are arranged in parallel; a fuel tank; a pressure sensor; a filter canister extraction valve; a first filter canister vent valve and a second filter canister vent valve; a first filter canister vent line, wherein the first filter canister vent line is directly connected to the first filter canister vent valve and directly connected to the second filter canister vent line, and the second filter canister vent line is also directly connected to the second filter canister vent valve, and the first filter canister vent line is directly connected to the second filter canister vent line; and a first filter canister load line, wherein the first filter canister load line is directly connected to the first carbon-filled fuel vapor storage filter canister. The system includes a gas storage filter, wherein the first carbon-filled fuel vapor storage filter is also directly connected to a second filter load line, and the second filter load line is also directly connected to the second carbon-filled fuel vapor storage filter; and a controller comprising executable instructions stored in a non-transitory memory, the executable instructions causing the controller to perform evaporative emission system diagnostics, the evaporative emission system diagnostics including a second phase in which the first filter vent valve is assessed as being in a normally open fault, the second filter vent valve is assessed as being in a normally open fault, the second filter vent valve is assessed as being in a normally closed fault, and the second filter vent line and the second filter load line are assessed as being blocked.

[0106] According to an embodiment, the second stage is part of a plurality of stages in the diagnostics of the evaporative emission system, and wherein in each of the plurality of stages, at least one of the filter canister extraction valve, the first filter canister vent valve, and the second filter canister vent valve is adjusted to an operational state.

[0107] According to an embodiment, the invention is further characterized by additional executable instructions that cause the controller to compare the pressure indicated by the pressure sensor with a predetermined pressure or pressure range to evaluate the first filter canister vent valve and the second filter canister vent valve.

[0108] According to an embodiment, the invention is further characterized by additional executable instructions that cause the controller to perform a zero-stage diagnostic of the evaporative emission system, in which the filter canister extraction valve is assessed as being in a normally closed fault.

[0109] According to an embodiment, the filter canister extraction valve is evaluated based on the output of the pressure sensor.

[0110] According to an embodiment, the invention is further characterized by additional executable instructions that cause the controller to perform a first stage of the evaporative emission system diagnostic, in which the first filter canister vent valve is assessed as being in a normally closed fault.

[0111] According to an embodiment, the invention is further characterized by additional executable instructions that cause the controller to perform a third stage of diagnostics of the evaporative emission system, in which the evaporative emission system is assessed to have a crack.

[0112] According to the present invention, a method for operating an evaporative emission system of a vehicle includes: during an initial phase of evaporative emission system diagnostics, commanding the opening of a first filter canister vent valve, a second filter canister vent valve, and a filter canister extraction valve, wherein the first filter canister vent valve and the second filter canister vent valve are arranged in parallel; during a first phase of evaporative emission system diagnostics, commanding the closing of the second filter canister vent valve and commanding the opening of the first filter canister vent valve and the filter canister extraction valve; during a second phase of evaporative emission system diagnostics, commanding the closing of the first filter canister vent valve and commanding the opening of the second filter canister vent valve and the filter canister extraction valve; and during a third phase of evaporative emission system diagnostics, commanding the closing of the first filter canister vent valve and the second filter canister vent valve and commanding the opening of the filter canister extraction valve.

[0113] In one aspect of the invention, the method includes generating an indication of evaporative emission degradation in response to a pressure sensor output being outside a threshold range during the initial phase of evaporative emission system diagnostics.

[0114] In one aspect of the invention, the method includes generating a second indication of evaporative emission degradation in response to the output of the pressure sensor being outside a second threshold range during a first phase of evaporative emission system diagnostics.

[0115] In one aspect of the invention, the method includes generating a third indication of evaporative emission degradation in response to the output of the pressure sensor being outside a third threshold range during a second phase of diagnostics of the evaporative emission system.

[0116] In one aspect of the invention, the method includes generating a fourth indication of evaporative emission degradation in response to the output of the pressure sensor being outside a fourth threshold range during the third phase of the evaporative emission system diagnostics.

Claims

1. A method for operating an evaporative emission system of a vehicle, comprising: During the diagnostic sequence, the parallel-arranged filter canister extraction valve and two filter canister vent valves are operated to diagnose the two filter canister vent valves and the two filter canister vent lines connecting the two filter canister vent valves; and An indication of deterioration in evaporative emissions is generated in response to the output of the pressure sensor generated during the diagnostic sequence.

2. The method of claim 1, wherein the two filter canister ventilation valves are connected to the outlet ventilation duct.

3. The method of claim 2, wherein the first of the two filter canister vent valves is connected to a first carbon-filled fuel vapor storage filter canister, and wherein the second of the two filter canister vent valves is connected to a second carbon-filled fuel vapor storage filter canister.

4. The method of claim 1, wherein the operation includes commanding to fully open and fully close the filter canister extraction valve and the two filter canister vent valves.

5. The method of claim 1, further comprising operating the filter canister extraction valve and the two filter canister vent valves in a plurality of diagnostic sequence stages, wherein the duration of each of the plurality of diagnostic sequence stages is time-based.

6. The method of claim 5, further comprising monitoring the output of the pressure sensor during each of the plurality of diagnostic sequence stages.

7. The method of claim 6, further comprising comparing the pressure determined based on the output of the pressure sensor with a predetermined pressure in each of the plurality of diagnostic sequence stages.

8. The method of claim 7, wherein during the second phase of the plurality of diagnostic sequence phases, the output of the pressure sensor is compared with a plurality of pressure ranges.

9. An evaporative emission system, comprising: A first carbon-filled fuel vapor storage filter canister, wherein the first carbon-filled fuel vapor storage filter canister and a second carbon-filled fuel vapor storage filter canister are arranged in parallel. Fuel tank; Pressure sensor; Filter can extraction valve; First filter tank ventilation valve; Second filter tank ventilation valve; The first filter tank ventilation pipeline is directly connected to the first filter tank ventilation valve and directly connected to the second filter tank ventilation pipeline. The second filter tank ventilation pipeline is also directly connected to the second filter tank ventilation valve. The first filter tank ventilation pipeline is directly connected to the second filter tank ventilation pipeline. A first filter tank load line is directly connected to the first carbon-filled fuel vapor storage filter tank, which is also directly connected to a second filter tank load line, which is also directly connected to the second carbon-filled fuel vapor storage filter tank; and The controller includes executable instructions stored in a non-transitory memory, the executable instructions causing the controller to perform evaporative emission system diagnostics, the evaporative emission system diagnostics including a second phase in which the first filter canister vent valve is assessed as being in a normally open fault, the second filter canister vent valve is assessed as being in a normally open fault, the second filter canister vent valve is assessed as being in a normally closed fault, and the second filter canister vent line and the second filter canister load line are assessed as being blocked.

10. The evaporative emission system of claim 9, wherein the second stage is part of a plurality of stages in the diagnostics of the evaporative emission system, and wherein in each of the plurality of stages, at least one of the filter canister extraction valve, the first filter canister vent valve, and the second filter canister vent valve is adjusted to an operational state.

11. The evaporative emission system of claim 10, further comprising additional executable instructions that cause the controller to compare a pressure indicated by the pressure sensor with a predetermined pressure or pressure range to evaluate the first filter canister vent valve and the second filter canister vent valve.

12. The evaporative emission system of claim 9, further comprising additional executable instructions that cause the controller to perform a zero-stage diagnostic of the evaporative emission system, in which the filter canister extraction valve is assessed as being in a normally closed fault.

13. The evaporative emission system of claim 12, wherein the filter can extraction valve is evaluated based on the output of the pressure sensor.

14. The evaporative emission system of claim 9, further comprising additional executable instructions that cause the controller to perform a first phase of diagnostics of the evaporative emission system, in which the first filter canister vent valve is assessed as being in a normally closed fault.

15. The evaporative emission system of claim 9, further comprising additional executable instructions that cause the controller to perform a third phase of diagnostics of the evaporative emission system, in which the evaporative emission system is assessed to have a crack.

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