Fault diagnosis device for a leakage diagnosis device

Abstract

A leak diagnosis device (60) diagnoses leaks of evaporative fuel in the evaporative fuel treatment unit (10). The evaporative fuel treatment unit purifies the evaporative fuel generated in the fuel tank (21) and adsorbed on the canister (23) to the intake passage (45). The leak diagnosis device includes: a vent valve (61) that blocks a first atmospheric passage (31) that connects the canister to an atmospheric opening; and a pump (62) that pressurizes and depressurizes a second atmospheric passage (32) that serves as a bypass passage to the first atmospheric passage. A fault diagnosis device diagnoses faults of the leak diagnosis device based on the output value of a pressure sensor (13) that detects the pressure in the passage connected to the canister.

Description

Technical Field

[0001] This disclosure relates to a fault diagnosis device for a leak diagnosis device. Background Technology

[0002] Traditionally, a device is known for diagnosing leaks in components, pipes, etc., of an evaporative fuel treatment system. The evaporative fuel treatment system collects evaporative fuel from the fuel tank and supplies it to the engine's intake manifold.

[0003] For example, the leak diagnosis device for an evaporative fuel processing apparatus disclosed in Patent Document 1 includes a tank vent valve (CVV), a vacuum pump, and two check valves (CV1, CV2). The tank vent valve is located in a first flow path between the tank and the atmosphere. The pump and check valves are located in a second flow path parallel to the first flow path.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: US 2020 / 0182174 A1

[0007] In the device according to Patent Document 1, when the leak diagnosis device fails and makes a determination result of "leakage has occurred" in the leak diagnosis, the device cannot determine whether the determination result is due to a leak in the evaporative fuel processing device or due to a malfunction of the leak diagnosis device. Summary of the Invention

[0008] The purpose of this disclosure is to provide a fault diagnosis device configured for diagnosing faults in a leak diagnosis device of an evaporative fuel processing unit.

[0009] This disclosure relates to a fault diagnosis device configured to perform fault diagnosis of a leak diagnosis device located in an atmospheric passage to diagnose leaks of evaporative fuel in an evaporative fuel treatment unit. The evaporative fuel treatment unit purifies the evaporative fuel adsorbed on the tank into an intake passage via a purification passage. The tank is connected to a fuel tank via a vapor passage and to an atmospheric opening via an atmospheric passage.

[0010] The leak diagnosis device includes a vent valve, a pump, and at least one check valve. The vent valve may correspond to the tank vent valve in Patent Document 1. The pump and check valve may correspond to the vacuum pump and check valves CV1 and CV2 in Patent Document 1.

[0011] A vent valve is configured to block a first atmospheric passage, which is the main channel of the atmospheric passage and connects the canister to an atmospheric opening. A pump is positioned to a second atmospheric passage, which is a bypass passage to the first atmospheric passage and connects the canister to the atmospheric opening. The pump is configured to pressurize and depressurize the second atmospheric passage. For example, when the pump supplies gas from the canister side to the atmospheric opening pressure, the pressure in the second atmospheric passage between the canister and the pump is reduced. At least one check valve is positioned in the second atmospheric passage and seals the airflow in the direction opposite to the pumping direction.

[0012] The fault diagnosis apparatus according to the first aspect of this disclosure is configured to diagnose faults based on the output value of a pressure sensor, which is configured to detect pressure in a channel connected to a tank.

[0013] The fault diagnosis device according to the second aspect of this disclosure diagnoses faults based on the pump current value.

[0014] According to the fault diagnosis device of the third aspect of this disclosure, fault diagnosis is performed based on the output value of the air-fuel ratio sensor in the following condition: a purge valve set to the purge passage is open to purge evaporated fuel from the canister to the intake passage. The air-fuel ratio sensor detects the air-fuel ratio of the air-fuel mixture supplied to the engine through the intake passage. Attached Figure Description

[0015] The above and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings:

[0016] Figure 1 This is a diagram showing the configuration of the evaporative fuel processing apparatus and the leak diagnosis apparatus according to the first to third embodiments.

[0017] Figure 2 This is a flowchart illustrating the leak diagnosis of a comparative example.

[0018] Figure 3 This is a flowchart (1) illustrating the fault diagnosis implemented by the fault diagnosis device of the first embodiment.

[0019] Figure 4 This is a flowchart (2) used for the same fault diagnosis.

[0020] Figure 5 It is a time graph under the condition of no system minor leaks and no LCM failures.

[0021] Figure 6 This is a time graph showing a small system leak.

[0022] Figure 7 This is a time graph showing the situation where the pump cannot be shut off.

[0023] Figure 8 This is a time graph showing the pump failure scenario.

[0024] Figure 9 This is a time graph showing the filter being clogged.

[0025] Figure 10 This is a time graph showing the situation where the check valve is stuck and closed.

[0026] Figure 11 This is a timeline of a major system leak.

[0027] Figure 12 This is a time graph showing the situation where the vent valve is stuck open.

[0028] Figure 13 This is a flowchart (1) illustrating the fault diagnosis implemented by the fault diagnosis device of the second embodiment.

[0029] Figure 14 This is a flowchart (2) used for the same fault diagnosis.

[0030] Figure 15 It is a time graph under the condition of no system minor leaks and no LCM failures.

[0031] Figure 16 This is a time graph showing a small system leak.

[0032] Figure 17 This is a time graph showing the situation where the pump cannot be shut off.

[0033] Figure 18 This is a time graph showing the pump failure scenario.

[0034] Figure 19 This is a time graph showing the situation where the check valve is stuck and closed.

[0035] Figure 20 This is a time graph showing the filter being clogged.

[0036] Figure 21 This is a timeline of a major system leak.

[0037] Figure 22 This is a time graph showing the situation where the vent valve is stuck open.

[0038] Figure 23 This is a flowchart illustrating the fault diagnosis implemented by the fault diagnosis device of the third embodiment.

[0039] Figure 24 This is a time graph showing the filter being clogged.

[0040] Figure 25This is a time graph showing the situation where the vent valve is stuck open.

[0041] Figure 26 This is a time graph showing situations where the pump malfunctions or the check valve is stuck shut.

[0042] Figure 27 This is a time graph showing the situation where the pump cannot be shut off.

[0043] Figure 28 This is a diagram showing the configuration of the evaporative fuel processing apparatus and the leak diagnosis apparatus according to the fourth embodiment.

[0044] Figure 29 This is a flowchart (1) illustrating the fault diagnosis implemented by the fault diagnosis device of the fourth embodiment.

[0045] Figure 30 This is a flowchart (2) used for the same fault diagnosis.

[0046] Figure 31 It is a time graph under the condition of no system minor leaks and no LCM failures.

[0047] Figure 32 This is a time graph showing a small system leak.

[0048] Figure 33 This is a time graph showing the situation where the pump cannot be shut off.

[0049] Figure 34 This is a time graph showing the pump failure scenario.

[0050] Figure 35 This is a time graph showing the filter being clogged.

[0051] Figure 36 This is a time graph showing the situation where the check valve is stuck and closed.

[0052] Figure 37 This is a timeline of a major system leak.

[0053] Figure 38 This is a time graph showing the situation where the vent valve is stuck open. Detailed Implementation

[0054] Hereinafter, several embodiments of the fault diagnosis apparatus according to the present disclosure will be described with reference to the accompanying drawings. This fault diagnosis apparatus performs fault diagnosis on a leak diagnosis device, specifically a vehicle fuel vapor treatment device. The fuel vapor treatment device uses a canister to collect fuel vapor evaporated from the fuel tank and supplies the collected vapor to the intake passage. Hereinafter, the fuel vapor treatment device is also referred to as the "system." The leak diagnosis apparatus is also referred to as a "leak detection module (LCM)."

[0055] (Overall configuration of evaporative fuel processing unit and leak diagnosis unit)

[0056] First, refer to Figure 1 Describe the overall configuration of the device. The system, namely the evaporative fuel processing device 10, includes a fuel tank 21, a steam passage 20, a tank 23, an atmospheric passage 30, a purification passage 40, etc.

[0057] Fuel tank 21, which stores fuel, is connected to tank 23 via steam passage 20. Tank 23 adsorbs evaporated fuel. Furthermore, in... Figure 1 In the example, the sealing valve 22 is located in the steam passage 20. Typically, the sealing valve 22 shuts off the fuel tank 21 from the canister 23 to seal the fuel tank 21 unless the vehicle is refueled. Note that the sealing valve 22 may also be omitted.

[0058] Atmospheric passage 30 connects tank 23 to atmospheric opening 33. Purification passage 40 connects tank 23 to air intake passage 45. Purification valve 42 is located in the middle of purification passage 40. With purification valve 42 open, the evaporated fuel adsorbed on tank 23, together with the air introduced through atmospheric passage 30, is purified through purification passage 40 and then sent to air intake passage 45.

[0059] In this way, the evaporative fuel treatment device 10 purifies the evaporative fuel adsorbed on the tank 23 through the purification passage 40 and into the intake passage 45. At this time, the amount of evaporative fuel to be purified is adjusted according to the opening of the purification valve 42. The air-fuel mixture formed by the intake air and evaporative fuel mixed in the intake passage 45 is supplied to the engine 50.

[0060] A leak diagnosis device 60 is installed in the atmospheric channel 30 to diagnose leaks of evaporative fuel in the evaporative fuel processing unit 10. In the leak diagnosis device 60, two channels constituting the atmospheric channel 30 are connected in parallel. A first atmospheric channel 31, serving as the main channel of the atmospheric channel 30, connects the tank 23 to the atmospheric opening 33. A second atmospheric channel 32, serving as a bypass channel of the first atmospheric channel 31, connects the tank 23 to the atmospheric opening 33. At the junction between the first atmospheric channel 31 and the second atmospheric channel 32, the junction on the tank 23 side is called Yc, and the junction on the atmospheric opening 33 side is called Ya.

[0061] The leak diagnostic device 60 includes a vent valve 61, a pump 62, two check valves 631 and 632, and a filter 64. The vent valve 61 is configured to shut off the first atmospheric passage 31. In this embodiment, the vent valve 61 includes a normally open solenoid valve.

[0062] Pump 62 is an electrically driven pump located in and powered by electricity in the second atmospheric passage 32. Pumps 62 and 62X in each embodiment are configured to pressurize or depressurize the second atmospheric passage 32. In pumps 62 and 62X, pump 62 in the first to third embodiments is configured to pump gas in the second atmospheric passage 32 from the tank 23 side toward the atmospheric opening 33. Operation of pump 62 depressurizes the second atmospheric passage 32 between tank 23 and pump 62. In the fourth embodiment described later, pump 62X pumps in the opposite direction.

[0063] Check valves 631 and 632 are provided to the second atmospheric passage 32 and seal the airflow in the direction opposite to the pumping direction of pump 62. Specifically, the first check valve 631 is provided between the manifold point Yc on the tank 23 side and pump 62. The second check valve 632 is provided between the manifold point Ya on the atmospheric opening 33 side and pump 62. The number of check valves is not limited to two; there can be one or more. Furthermore, the check valves can adopt various structures. A filter 64 is provided to the atmospheric passage 30 between the manifold point Ya and the atmospheric opening 33 on the atmospheric opening 33 side.

[0064] Furthermore, as a sensor typically used by the leak diagnosis device 60 for leak diagnosis, a pressure sensor 13 is provided to detect the pressure in the channel connected to the tank 23. Figure 1 In the example, pressure sensor 13 is disposed in atmospheric passage 30 between manifold Yc and tank 23 on one side of tank 23. Alternatively, for example, pressure sensor 13 may be disposed in a first atmospheric passage 31 between manifold Yc and vent valve 61 and / or may be disposed in a second atmospheric passage 32 between manifold Yc and first check valve 631. Alternatively, pressure sensor 13 may be disposed in vapor passage 20 between sealing valve 22 and tank 23.

[0065] In addition, an air-fuel ratio sensor (λ sensor) 15 is provided on the exhaust side of the engine 50 to detect the air-fuel ratio of the air-fuel mixture supplied to the engine 50 through the intake passage 45, which is typically used for engine control.

[0066] Patent document 1 (US 2020 / 0182174 A1) discloses an evaporative fuel processing device 10 having such a configuration. Figure 2 The flowchart illustrates a leak diagnosis method based on the comparative example mentioned in Patent Document 1. Hereinafter, in the description of the flowchart, the symbol "S" denotes a step. Figure 2 At the start, purification valve 42 is closed.

[0067] In S91, the vent valve 61 corresponding to the tank vent valve in Patent Document 1 is closed. When pump 62 is turned on in S92, and there is no leak in the leak diagnosis device 60, the passage on the tank 23 side is reduced from atmospheric pressure to negative pressure. In S93, it is determined whether the output value of pressure sensor 13 is equal to or less than a predetermined pressure threshold (<atmospheric pressure). In S94, pump 62 is turned off. In S96, it is determined whether the rate of change of the output value of pressure sensor 13 after the pump is turned off is equal to or less than a predetermined speed threshold. If it is determined to be yes in S96, it is determined in S97 that there is no leak in the system. If it is determined to be no in S93 or no in S95, it is determined in S98 that there is a leak in the system.

[0068] However, Patent Document 1 assumes that the leak diagnosis device 60 has not failed. In other words, Patent Document 1 does not consider the possibility of each component of the leak diagnosis device 60 malfunctioning. Therefore, in the device according to Patent Document 1, if the leak diagnosis device 60 fails and a "leak has occurred" determination is made in the leak diagnosis, the device cannot determine whether the determination is due to a leak in the evaporative fuel processing device 10 or a malfunction in the leak diagnosis device 60. To solve this problem, the fault diagnosis device 80 of this embodiment is capable of diagnosing malfunctions in the leak diagnosis device 60.

[0069] The fault diagnosis device 80 of this embodiment performs fault diagnosis based on one or more of the following parameters: (1) the output value Psns of the pressure sensor 13, (2) the current value Imp of the pump 62, and (3) the output value A / F of the air-fuel ratio sensor 15. Hereinafter, the output value Psns of the pressure sensor 13 is referred to as "pressure sensor output value Psns". The current value Ipump of the pump 62 is referred to as "pump current Ipump". The output value A / F of the air-fuel ratio sensor 15 is referred to as "air-fuel ratio sensor output value A / F".

[0070] Specifically, in the first embodiment, fault diagnosis is performed based on the pressure sensor output value Psns. In the second embodiment, fault diagnosis is performed based on the pressure sensor output value Psns and the pump current Imp. In the third embodiment, fault diagnosis is performed based on the air-fuel ratio sensor output value A / F. Figure 1 As shown by the dashed arrows, the fault diagnosis device 80 does not need to periodically acquire the three parameters, and according to this embodiment, it can acquire only the parameters to be used.

[0071] (For fault diagnosis of leak diagnosis devices)

[0072] Next, fault diagnosis of the leakage diagnosis device 60 using the fault diagnosis device 80 will be described for each embodiment based on flowcharts and timelines. In the first and second embodiments, a portion of the flowchart is shared, and substantially identical steps are assigned the same step numbers. Furthermore, the flowcharts of the first and second embodiments are represented on the two diagrams by connection symbols J1 and J2, respectively. The step numbers of some defined steps in 60 correspond to the codes of the failed components.

[0073] Fault diagnosis is performed while the vehicle is stationary, for example, several hours after the ignition is turned off. In the second and third embodiments, the system's own leak diagnosis and the fault diagnosis of the leak diagnosis device 60 (“LCM” in the figures) are performed simultaneously. As a rough indication, a “large leak” in the system refers to a leak equal to or greater than the flow rate when the vent valve 61 is open, and is considered to have occurred when the valve is not closed or the pipe connection is disconnected. On the other hand, a “small leak” refers to a minor leak caused by a pinhole or the like.

[0074] Each timeline together shows the opening / closing of purge valve 42, vent valve 61, and pump 62. For normally closed purge valve 42, ON indicates open and OFF indicates closed. For normally open vent valve 61, ON indicates closed and OFF indicates open. In the first and second embodiments, purge valve 42 is always closed.

[0075] Furthermore, the time graph of the first embodiment shows the pressure sensor output value Psns. Some figures further show the system temperature, i.e., the ambient temperature of the leak diagnostic device 60. Here, the increase in system temperature relative to the initial temperature is shown. The time graph of the second embodiment shows the pump current Impump and the pressure sensor output value Psns. In the first to third embodiments, when the pump 62 is operating normally, the pressure sensor output value Psns changes from atmospheric pressure to the negative side. The time graph of the third embodiment shows the air-fuel ratio sensor output value A / F.

[0076] The flowchart and timeline are described below with reference to each other. The figure numbers in parentheses within the flowchart steps indicate the corresponding timeline figure numbers. It is important to note that the main entity opening / closing pump 62 and vent valve 61 in each step is the fault diagnosis device 80. However, describing this as "fault diagnosis device 80 opens pump 62" becomes redundant. Therefore, pump 62 and vent valve 61 are generally described in the passive voice, such as "pump 62 is opened."

[0077] (First Embodiment)

[0078] Reference Figures 3 to 12The fault diagnosis of the first embodiment is described. The following pressure thresholds have the relationships "PE>PD>Atmospheric pressure>PC>PA>PB" and "Atmospheric pressure>PF>PA". Figure 3 At the beginning, the purge valve 42 is closed. At time t1, in S11, the vent valve 61 is closed, and in S12, the pump 62 is turned on. When the leak diagnosis device 60 is functioning normally, the first atmospheric passage 31 is blocked, and air can be vented from the tank 23 to the atmospheric opening 33 through the second atmospheric passage 32.

[0079] At time t2, in S13, determine whether the pressure sensor output value Psns is equal to or less than the threshold PA. Figures 5 to 7 In step S13, the pressure sensor output value Psns is equal to or less than the threshold PA, and this is determined to be true. Therefore, pump 62 is shut down in step S14. If the condition in step S13 is false, step S60 determines that "the vent valve is stuck open, or the pump is faulty, or the check valve is stuck closed, or the filter is clogged, or there is a large leak in the system." The process proceeds to step S65. Figure 4 Here, "check valve closed and stuck" means that at least one of the first check valve 631 and the second check valve 632 is closed and stuck.

[0080] In S15, following S14, it is determined whether the pressure sensor output value Psns is equal to or greater than the threshold PB. If it is determined to be yes, the process proceeds to S17. In S14, when the system and leak diagnostic device 60 are normal, the second atmospheric passage 32 is blocked, and the pressure in the system is maintained.

[0081] In S17, it is determined whether the time it takes for the pressure sensor output value Psns to reach the threshold PC after pump 62 is turned off is greater than the threshold TQ. That is, the pressure sensor output value Psns at time t3, which is after time t2 has passed the threshold TQ, is compared with the threshold PC.

[0082] like Figure 5 As shown, when the pressure sensor output value Psns at time t3 is less than the threshold PC, and this is determined in S17, then in S70 it is determined that "no small leaks and no LCM faults have occurred in the system". Figure 6 As shown, when the pressure sensor output value Psns at time t3 is equal to or greater than the threshold PC and is determined to be no in S17, a "small leak in the system" is determined to have occurred in S68.

[0083] Returning to S15, as follows Figure 7 As shown, when the pressure sensor output value Psns continues to decrease and falls below the threshold PB after the pump shut-off command is issued, it is determined in S66 that "pump cannot shut off" has occurred.

[0084] Subsequently, reference Figure 4After confirming no in S13, pump 62 is shut off in S14. In S21, the pressure sensor output value Psns of the leak diagnosis device 60 is checked when the ambient temperature changes (in this case, increases). Here, the system temperature can be positively heated by a heating device or the like. Alternatively, this process can wait for the temperature to rise as the daytime temperature increases. When the system is blocked and the temperature rises, the air in the pipes expands, and the pressure in the pipes increases. Therefore, the pressure sensor output value Psns changes with the system temperature.

[0085] exist Figures 8 to 12 In the process, the system temperature rises from time t2 to time t6. In S22, it is determined whether the pressure sensor output value Psns after the temperature rise is equal to or greater than the threshold PD. If the pressure sensor output value Psns is less than the threshold PD, it is determined to be negative in S22, and "the vent valve is stuck or there is a large leak in the system" is determined in S615. If it is determined to be positive in S22, it is further determined in S23 whether the pressure sensor output value Psns is equal to or greater than the threshold PE. The thresholds PD and PE can be set at an appropriate time according to the system temperature after the system temperature rises.

[0086] like Figure 8 As shown, when the pressure sensor output value Psns after the temperature rises is equal to or greater than the threshold PD and less than the threshold PE, it is determined to be "no" in S23. In this case, it is assumed that the ventilation of the second atmospheric channel 32 is normal, and the factor determined to be "no" in S13 is determined to be "pump failure" in S62.

[0087] When the pressure sensor output value Psns after the temperature rises is equal to or greater than the threshold PE, it is determined to be true in S23, and "check valve stuck or filter clogged" is determined to have occurred in S634. Then, at time t6, the vent valve 61 is opened in S24, and in S25, it is determined again whether the pressure sensor output value Psns is equal to or greater than the threshold PE. Figure 9 As shown, when it is determined to be yes in S25, "filter blockage" is determined to have occurred in S64. Figure 10 As shown, when the vent valve 61 is open and the pressure sensor output value Psns is lower than the threshold PE, it is determined in S25 that no, and in S63 it is determined that "check valve closed stuck" has occurred.

[0088] On the other hand, in S26 following S615, after confirming the stability of the system temperature, pump 62 is turned on at time t7, in S28. In S29, it is determined whether the time it takes for the pressure sensor output value Psns to reach the threshold PF after pump 62 is turned on is greater than the threshold TR. That is, the pressure sensor output value Psns at time t8, after time t7 has passed the threshold TR, is compared with the threshold PF.

[0089] like Figure 11 As shown, when the pressure sensor output value Psns at time t8 is greater than the threshold PF, it is determined in S29 that a "major leak in the system" has occurred, and in S65, it is determined that a "major leak in the system" has occurred. When a major leak occurs in the system, pump 62 draws gas containing evaporated fuel. Therefore, the pump load becomes greater than when pump 62 draws gas without evaporated fuel. Therefore, it takes a long time to reduce the pressure in the pipeline to the threshold PF.

[0090] like Figure 12 As shown, when the pressure sensor output value Psns at time t8 is equal to or less than the threshold PF, it is determined to be no in S29, and "vent valve opening jamming" is determined to have occurred in S61. In the event of vent valve 61 opening jamming, pump 62 draws gas without evaporated fuel. Therefore, the pump load is small, and the pressure in the pipeline drops to the threshold PF in a short time.

[0091] As described above, the fault diagnosis in the first embodiment includes the step of evaluating the pressure sensor output value Psns when the vent valve 61 is closed and the pump 62 is open. S13 corresponds to this step. Here, as a specific method for evaluating the pressure sensor output value Psns, the pressure sensor output value Psns is compared with a predetermined pressure threshold.

[0092] Furthermore, the fault diagnosis in the first embodiment also includes a step of evaluating the change in the pressure sensor output value Psns immediately after shutting down the open pump 62 with the vent valve 61 closed. S17 corresponds to this step. Here, as a specific method for evaluating the change in the pressure sensor output value Psns, the time it takes for the pressure sensor output value Psns to reach a predetermined pressure threshold is compared with a predetermined time threshold.

[0093] The fault diagnosis in the first embodiment further includes a step of immediately evaluating the change in the pressure sensor output value Psns after turning on the closed pump 62 with the vent valve 61 closed. S29 corresponds to this step. The specific method for evaluating the change in the pressure sensor output value Psns is similar to the method described above.

[0094] The fault diagnosis in the first embodiment also includes a step of evaluating the pressure sensor output value Psns when the ambient temperature of the leak diagnosis device 60 changes with the vent valve 61 closed and the pump 62 closed. S22 and S23 correspond to this step.

[0095] The fault diagnosis device 80 of the first embodiment is configured to perform various types of fault diagnosis of the leak diagnosis device 60 by combining the above-described steps. Therefore, the fault diagnosis device 80 is able to appropriately distinguish between leaks in the evaporative fuel processing device 10 and faults in the leak diagnosis device 60.

[0096] (Second Embodiment)

[0097] Reference Figures 13 to 22 The fault diagnosis of the second embodiment is described. Descriptions that overlap with the first embodiment will be omitted as appropriate. S11 to S14 are the same as in the first embodiment. When pump 62 is turned on at time t1 to t2, and when the leak diagnosis device 60 is functioning normally, the pump current Impump becomes the reference value I0. The pump current thresholds have the following relationships: “IH>I0>IG(>0)” and “IK>IL>I0>IM”.

[0098] After shutting down pump 62 in S14, it is determined in S31 whether the pump current Impump is equal to or less than a threshold IG, which is a small value close to 0. If it is determined to be yes in S31, the process proceeds to S17, and thereafter, the same process as in the first embodiment is performed. Figure 15 As shown, when it is determined to be yes in S17, it is determined in S70 that "no small leaks and no LCM faults have occurred in the system". Figure 16 As shown, when it is determined to be no in S17, it is determined in S68 that "a small leak in the system" has occurred.

[0099] Returning to S31, as follows Figure 17 As shown, when the pump current Impump is greater than the threshold IG after the pump shut-off command is issued, it is determined to be no in S31, and it is determined in S66 that "the pump cannot be shut off" has occurred.

[0100] Subsequently, reference Figure 14 After determining "no" in S13, in S33, it is determined whether the pump current Imp is greater than or equal to the threshold IK. For example... Figure 18 As shown, when it is determined to be true in S33, a "pump failure" is determined to have occurred in S62.

[0101] If S33 is determined to be no, then in S34, determine whether the pump current Imp is greater than the threshold IL and equal to or less than the threshold IK. If S34 is determined to be yes, then in S634, determine that "check valve stuck or filter clogged" has occurred. If S34 is determined to be no, then in S615, determine that "vent valve stuck or large leakage in the system" has occurred.

[0102] Following S634, in S24, the vent valve 61 is opened at time t5. In S35, it is determined whether the pump current Impump is greater than the threshold IL and equal to or less than the threshold IK. Figure 19 As shown, the pump current Imp does not change even when the vent valve 61 is open, and this is confirmed in S35. Subsequently, it is confirmed in S63 that "check valve stuck" has occurred. Figure 20As shown, when the vent valve 61 opens and the pump current Impump drops below the threshold IL, it is determined in S35 that no. Subsequently, it is determined in S64 that "filter blockage" has occurred.

[0103] Following S615, in S36, it is determined whether the pump current Imp is greater than the threshold IM and equal to or less than the threshold IL. For example... Figure 21 As shown, when it is determined to be true in S36, a "major leak in the system" is determined to have occurred in S65. Figure 22 As shown, when the pump current Impump is equal to or less than the threshold IM, it is determined to be no in S36. Subsequently, it is determined in S61 that "vent valve opening stuck" has occurred.

[0104] As described above, in the state where the vent valve 61 is closed and the pump 62 is open, or the open pump 62 is closed, the fault diagnosis device 80 of the second embodiment diagnoses at least the fault of the pump 62 based on the pump current Imp. S33, S34, S35 and S36 correspond to the fault diagnosis in the state where the pump 62 is open, and S31 corresponds to the fault diagnosis in the state where the open pump 62 is closed.

[0105] Furthermore, the fault diagnosis device 80 of the second embodiment performs fault diagnosis by incorporating the determination of the pressure sensor output value Psns. In this way, the fault diagnosis device 80 can perform various types of fault diagnoses of the leak diagnosis device 60. Therefore, the fault diagnosis device 80 can appropriately distinguish between leaks in the evaporative fuel processing device 10 and faults in the leak diagnosis device 60.

[0106] (Third Embodiment)

[0107] Reference Figures 23 to 26 The fault diagnosis of the third embodiment is described. In the third embodiment, the fault diagnosis device 80 performs fault diagnosis based on the output value of the air-fuel ratio sensor 15, and simultaneously opens the purge valve 42 to purify the evaporated fuel from the tank 23 to the intake passage 45. In the third embodiment, unlike the first and second embodiments, system leak diagnosis is not performed simultaneously; only the fault diagnosis of the leak diagnosis device 60 is performed. Then, after confirming that the leak diagnosis device 60 is not faulty, the leak diagnosis device 60 is used again to perform system leak diagnosis.

[0108] In the third embodiment, τ1 to τ4 are used as time symbols on the horizontal axis of the time graph to distinguish them from those in the first and second embodiments. Ellipses displayed in the graph by alternating long and short dashed lines represent points of interest. The air-fuel ratio thresholds are related as “λA>λC>14.7 (ideal value)”.

[0109] At time τ1, in S41, the purge valve 42 is opened, and purge is performed. When the passage from the atmospheric opening 33 to the purge valve 42 is open, when purge begins, evaporated fuel is introduced into the intake passage 45, and the air-fuel ratio A / F of the air-fuel mixture becomes the ideal value of 14.7. When the passage is blocked, almost no evaporated fuel is introduced into the intake passage 45. Therefore, the air-fuel mixture becomes lean, and the air-fuel ratio A / F becomes a value greater than the ideal value of 14.7. In S42, it is determined whether the air-fuel ratio sensor output value A / F is equal to or less than the threshold λA. Figure 24 As shown, when the air-fuel ratio sensor output value A / F is greater than the threshold λA, it is determined to be no in S42. Subsequently, it is determined in S64 that "filter blockage" has occurred.

[0110] If it is determined to be yes in S42, then at time τ2, in S43, the vent valve 61 is closed. Subsequently, in S44, it is determined whether the air-fuel ratio sensor output value A / F is greater than the threshold λA. Figure 25 As shown, when the air-fuel ratio sensor output value A / F is equal to or less than the threshold λA, it is determined to be no in S44. Subsequently, it is determined in S61 that "ventilation valve opening stuck" has occurred.

[0111] When it is determined to be yes in S44, at time τ4, in S48, the vent valve 61 is opened, and in S49, the pump 62 is turned on. When the pump 62 is operating normally, the evaporated fuel is drawn towards the atmospheric opening 33, preventing the evaporated fuel from being introduced into the intake passage 45. Therefore, the air-fuel ratio A / F should increase. In S50, it is determined whether the air-fuel ratio sensor output value A / F is greater than the threshold λC. Figure 26 As shown, when the air-fuel ratio sensor output value A / F is equal to or less than the threshold λC, it is determined to be no in S50. Subsequently, it is determined in S623 that "pump failure or check valve stuck" has occurred.

[0112] When it is determined to be yes in S50, pump 62 is shut off in S51 at time τ5. When pump 62 stops normally, the suction of evaporated fuel stops, and the air-fuel ratio A / F should be close to the ideal value. In S52, it is determined whether the air-fuel ratio sensor output value A / F is equal to or less than the threshold λC. Figure 27 As shown, when the air-fuel ratio sensor output value A / F is greater than the threshold λC, it is determined to be no in S52. Subsequently, it is determined in S66 that "pump cannot be shut off" has occurred.

[0113] In summary, the fault diagnosis of the third embodiment includes the step of evaluating the output value of one or more air-fuel ratio sensors in one of the following states (1) to (3). Thus, the fault diagnosis device 80 is able to perform fault diagnosis of the leak diagnosis device 60 based on the air-fuel ratio sensor output value A / F. Therefore, the fault diagnosis device 80 is able to appropriately distinguish between a leak in the evaporative fuel treatment device 10 and a fault in the leak diagnosis device 60.

[0114] (1) The state in which the vent valve 61 is open and the pump 62 is closed. S42 corresponds to this state.

[0115] (2) The state in which the vent valve 61 is closed and the pump 62 is closed. S44 corresponds to this state.

[0116] (3) The state in which the vent valve 61 is open and the pump 62 is open. S50 corresponds to this state.

[0117] (Fourth Embodiment)

[0118] As described above, in the first to third embodiments, the pump 62 is configured to pump gas in the second atmospheric passage 32 from the tank 23 side toward the atmospheric opening 33. Operation of the pump 62 depressurizes the second atmospheric passage 32 between the tank 23 and the pump 62. On the other hand, as a fourth embodiment, a configuration in which the pumping direction of the pump 62X is opposite to that of the first to third embodiments will be described. (Refer to the accompanying drawings.) Figures 28 to 38 The fault diagnosis of the fourth embodiment is described.

[0119] like Figure 28 As shown, in the fourth embodiment, the pumping direction of pump 62X in the second atmospheric passage 32 of the leak diagnostic device 60 and the directions of check valves 631X and 632X are aligned with... Figure 1 The directions are reversed in the illustrated configuration. Therefore, the pump 62X of the fourth embodiment is configured to pump gas in the second atmospheric passage 32 from the atmospheric opening 33 side toward the tank 23. This operation of the pump 62 pressurizes the second atmospheric passage 32 between the tank 23 and the pump 62.

[0120] While using the fault diagnosis concept of the first embodiment in general, fault diagnosis in the leak diagnosis device 60 with this configuration can be performed based on the pressure sensor output value Psns by changing the relationship between the pressure sensor output value Psns and the threshold in some steps. Figures 29 to 38 The flowchart and timeline correspond to the first embodiment, respectively. Figures 3 to 12 The following will primarily describe the differences from the first embodiment.

[0121] exist Figure 29 and 30 In the flowchart, "X" is added to a section that is different. Figure 3 and Figure 4 The end of the step number. The threshold signs of S13X, S15X, S17X, and S29X, and the orientation of the inequality signs of S13X and S15X. Figure 3 and 4 The difference. Figures 31 to 38 The positive pressure thresholds Pa, Pb, Pc, and Pf in the time graph are obtained by... Figures 5 to 14The negative pressure thresholds PA, PB, PC, and PF are obtained by reversing them to the positive side of atmospheric pressure.

[0122] When the system temperature rises, the pressure thresholds PD and PE used for diagnosis are similar to those in the first embodiment. Therefore, in the fourth embodiment, the pressure thresholds have the relationships of "Pb>Pa>Pc>Atmospheric pressure", "PE>PD>Atmospheric pressure", and "Pa>Pf>Atmospheric pressure". Fault diagnosis similar to that in the first embodiment can be performed in this way, except for the changes in the pressure threshold relationships.

[0123] like Figure 31 As shown, in Figure 29 In S70, it is determined that "no small leaks and no LCM failures have occurred in the system". In S67, as... Figure 32 As shown, it is determined that a "small leak in the system" has occurred. In S66, as... Figure 33 As shown, the "pump cannot be shut off" error is confirmed. In S62, as... Figure 34 As shown, a "pump failure" has been confirmed.

[0124] exist Figure 30 In S64, such as Figure 35 As shown, it is determined that "filter clogging" has occurred. In S63, as... Figure 36 As shown, it is confirmed that a "check valve stuck" error has occurred. In S65, as... Figure 37 As shown, it is determined that a "major leak in the system" has occurred. In S61, as... Figure 38 As shown, this confirms that the "vent valve is stuck when it opens" error has occurred.

[0125] Even in the fourth embodiment configuration where the pumping direction of the pump 62X of the leak diagnosis device 60 is opposite, various types of fault diagnosis of the leak diagnosis device 60 can be performed. Therefore, the fault diagnosis device 80 is able to properly distinguish between leaks in the evaporative fuel processing device 10 and faults in the leak diagnosis device 60.

[0126] (Other embodiments)

[0127] (a) The fault diagnosis of the first and second embodiments is not limited to being performed when the purge valve 42 is periodically closed. Fault diagnosis can also be performed when the vent valve 42 is open, as long as system pressure can be detected.

[0128] (b) The pressure change in S21 of the first embodiment "when the temperature changes" is not limited to a pressure increase caused by a temperature increase. A pressure decrease caused by a temperature decrease can be used. In this case, in addition to using a forced cooling system such as a fan, the system temperature can be reduced after the engine stops, and / or the system can wait for the system temperature to decrease as the nighttime temperature decreases.

[0129] (c) In the step of evaluating the change in the pressure sensor output value Psns during an operation, the method of comparing the time when the pressure sensor output value Psns reaches a predetermined pressure threshold with a predetermined time threshold corresponds to an evaluation based on an average rate. Alternatively, for example, the change can be evaluated based on an instantaneous rate calculated from the difference in the pressure sensor output values ​​Psns within one minute immediately following the operation.

[0130] (d) The sequence of steps in the flowcharts of each of the above embodiments is an example. The sequence of steps can be changed as needed, as long as fault diagnosis can be performed. Furthermore, for example, if it is known in advance that a certain component of the leak diagnostic device 60 is normal, some steps can be omitted.

[0131] This disclosure should not be limited to the above embodiments, and various other embodiments may be implemented without departing from the scope of the invention.

[0132] The controllers and methods described in this disclosure can be implemented by a special-purpose computer created by configuring a processor programmed to perform one or more specific functions contained in a computer program. Alternatively, the devices and methods described in this disclosure can be implemented by special-purpose hardware logic circuitry. More alternatively, the devices and methods described in this disclosure can be implemented by a combination of one or more special-purpose computers created by configuring a processor to execute a computer program and one or more hardware logic circuits. The computer program can be stored as instructions for computer execution on a tangible, non-transitory computer-readable medium.

Claims

1. A fault diagnosis device configured to perform fault diagnosis of a leak diagnosis device (60) disposed at an atmospheric passage (30) to diagnose leakage of evaporative fuel in an evaporative fuel treatment device (10), the evaporative fuel treatment device being configured to purify evaporative fuel adsorbed on a tank (23) through a purification passage (40) to an air intake passage (45), the tank being connected to a fuel tank (21) via a steam passage (20) and to an atmospheric opening (33) via the atmospheric passage. The leak diagnostic device includes: A vent valve (61) is configured to block a first atmospheric passage (31), which is the main channel of the atmospheric passage, and connect the tank to the atmospheric opening. A pump (62) is provided to a second atmospheric passage (32), which is a bypass passage to the first atmospheric passage and connects the tank to the atmospheric opening, and the pump (62) is configured to pressurize and depressurize the second atmospheric passage. At least one check valve (631, 632) is disposed in the second atmospheric passage and configured to seal the flow in the direction opposite to the pumping direction of the pump, and A filter (64) is disposed between the confluence point (Ya) and the atmospheric opening (33) to the atmospheric channel (30), wherein the confluence point (Ya) is located between the first atmospheric channel (31) and the second atmospheric channel (32) and on one side of the atmospheric opening (33). The fault diagnosis device includes: A processor configured to perform the fault diagnosis based on the output value of a pressure sensor (13), the pressure sensor (13) being configured to detect pressure in a channel connected to the tank, wherein The processor is configured to In the fault diagnosis, the output value of the pressure sensor is evaluated with the vent valve closed and the pump open. 1) When the output value of the pressure sensor is greater than a first threshold (PA), diagnose one or more of the following events: The pump malfunction, The check valve is stuck shut. The filter is clogged. The vent valve is stuck when it is opened, and A large leak occurred in the evaporative fuel processing unit, and 2) When the output value of the pressure sensor is equal to or less than the first threshold (PA), In the fault diagnosis, immediately after turning off the pump with the vent valve closed, the change in the output value of the pressure sensor is evaluated, and when the output value of the pressure sensor is greater than or equal to a second threshold (PB) that is smaller than the first threshold (PA), i) When the time it takes for the output value of the pressure sensor to reach a third threshold (PC) that is greater than the first threshold (PA) is not greater than a fourth threshold (TQ), a small leak in the evaporative fuel processing device is diagnosed. ii) When the time it takes for the output value of the pressure sensor to reach the third threshold (PC) is greater than the fourth threshold (TQ), it is diagnosed that a small leak in the evaporative fuel processing unit has not occurred. The term "major leakage" refers to a leakage equal to or greater than the flow rate when the vent valve (61) is open, and is considered to have occurred when the valve is not closed or the pipeline connection is disconnected. The term "small leak" refers to a tiny leak caused by a pinhole.

2. The fault diagnosis device according to claim 1, wherein... The processor is configured to, during the fault diagnosis, immediately after turning on the closed pump while the vent valve is closed, evaluate the change in the output value of the pressure sensor.

3. The fault diagnosis device according to claim 1 or 2, wherein... The processor is configured to, during the fault diagnosis, evaluate the output value of the pressure sensor when the ambient temperature of the leak diagnosis device changes, with the vent valve closed and the pump closed.

4. A fault diagnosis device configured to perform fault diagnosis of a leak diagnosis device (60) disposed at an atmospheric passage (30) to diagnose leakage of evaporative fuel in an evaporative fuel treatment device (10), the evaporative fuel treatment device being configured to purify evaporative fuel adsorbed on a tank (23) through a purification passage (40) to an air intake passage (45), the tank being connected to a fuel tank (21) via a steam passage (20) and to an atmospheric opening (33) via the atmospheric passage. The leak diagnostic device includes: A vent valve (61) is configured to block a first atmospheric passage (31), which is the main channel of the atmospheric passage, and connect the tank to the atmospheric opening. A pump (62) is provided to a second atmospheric passage (32), which is a bypass passage to the first atmospheric passage and connects the tank to the atmospheric opening, and the pump (62) is configured to pressurize and depressurize the second atmospheric passage. At least one check valve (631, 632) is disposed in the second atmospheric passage and configured to seal the flow in the direction opposite to the pumping direction of the pump, and A filter (64) is disposed between the confluence point (Ya) and the atmospheric opening (33) to the atmospheric channel (30), wherein the confluence point (Ya) is located between the first atmospheric channel (31) and the second atmospheric channel (32) and on one side of the atmospheric opening (33). The fault diagnosis device includes: A processor is configured to perform the fault diagnosis in conjunction with the determination of the output value of a pressure sensor (13), which is configured to detect pressure in a channel connected to the tank, and the processor performs the fault diagnosis based on the current value of the pump, wherein... The processor is configured to In the fault diagnosis, based on the current value of the pump when it is open, with the vent valve closed, and 1) When the output value of the pressure sensor is greater than a first threshold (PA), diagnose one or more of the following events: The pump malfunction, The check valve is stuck shut. The filter is clogged. The vent valve is stuck when it is opened, and A large leak occurred in the evaporative fuel processing unit, and 2) When the output value of the pressure sensor is equal to or less than the first threshold (PA), In the fault diagnosis, the current value of the pump after it was opened and then closed is used when the vent valve is closed. i) When the pump's current value (Impump) is greater than the threshold (IG), diagnose that the pump cannot be shut down, and ii) When the pump's current value (Impump) is equal to or less than the threshold (IG), the inability to shut down the pump is diagnosed as not occurring. The large leakage refers to a leakage that is equal to or greater than the flow rate when the vent valve (61) is open, and is considered to have occurred when the valve is not closed or the pipeline connection is disconnected.

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