Leakage diagnosis device Fault diagnosis device

Abstract

The leakage diagnosis device (60) of the evaporative fuel treatment device (10) includes a first vent valve (61), a second vent valve (67), and a pump (62). The first vent valve (61) can cut off the first atmospheric passage (31) which is a main passage of the atmospheric passage (30) and connects the adsorption tank (23) with the atmospheric opening (33). The second vent valve (67) can cut off the second atmospheric passage (32) which is a bypass passage of the first atmospheric passage (31) and connects the adsorption tank (23) with the atmospheric opening (33). The pump (62) is provided in the second atmospheric passage (32) at a position closer to the atmospheric opening (33) than the second vent valve (67) and can pressurize or depressurize the second atmospheric passage (32). The fault diagnosis device (80) performs fault diagnosis based on the output value (Psns) of the pressure sensor (13), the current value (Ipump) of the pump (62), or the output value (A / F) of the air-fuel ratio sensor (15).

Description

[0001] Related Application

[0002] This application is based on Japanese Patent Application No. 2020-165591 filed on September 30, 2020, and the contents thereof are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a fault diagnosis device of a leakage diagnosis device. Background Art

[0004] Conventional evaporative fuel treatment devices that recover evaporated fuel from a fuel tank and supply it to the intake passageway are known to diagnose leaks in components, piping, and the like. For example, Patent Document 1 discloses a leak diagnosis device for an evaporative fuel treatment device that includes a CVV (canister vent valve), a CVV check valve, and a pump. The CVV is installed in a first flow path between the canister and the atmosphere. The CVV check valve and pump are installed in a second flow path formed in parallel with the first flow path.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent Publication No. US2019 / 0368447A1 Summary of the Invention

[0008] In the prior art of Patent Document 1, when a leak diagnosis device fails, it is impossible to distinguish whether the determination result of "leak present" in leak diagnosis is due to a leak in the evaporated fuel processing device or due to a failure of the leak diagnosis device.

[0009] An object of the present disclosure is to provide a fault diagnosis device capable of diagnosing a fault in a leak diagnosis device of an evaporated fuel processing device.

[0010] The present disclosure relates to a fault diagnosis device for diagnosing a failure of a leak diagnosis device. The leak diagnosis device is provided in an atmospheric passage of an evaporated fuel treatment device to diagnose leaks of evaporated fuel. The evaporated fuel treatment device purifies evaporated fuel adsorbed by an adsorption canister into an intake passage via a purge passage. The adsorption canister is connected to a fuel tank via a vapor passage and to an atmospheric opening via an atmospheric passage.

[0011] The leakage diagnosis device includes a first vent valve, a second vent valve, and a pump. The first vent valve corresponds to the CVV in Patent Document 1. The second vent valve and the pump correspond to the CVV check valve and the pump in Patent Document 1.

[0012] The first vent valve is capable of shutting off a main passage serving as an atmospheric passage, thereby connecting the canister to the atmospheric opening. The second vent valve is capable of shutting off a bypass passage serving as an atmospheric passage, thereby connecting the canister to the atmospheric opening. A pump is disposed in the second atmospheric passage, closer to the atmospheric opening than the second vent valve, and is capable of pressurizing or depressurizing the second atmospheric passage.

[0013] The fault diagnosis device according to the first aspect performs fault diagnosis based on an output value of a pressure sensor that detects the pressure of a passage connected to the canister.

[0014] The fault diagnosis device according to the second aspect performs fault diagnosis based on the current value of the pump.

[0015] The fault diagnosis device of the third aspect performs fault diagnosis based on the output value of an air-fuel ratio sensor while a purge valve provided in the purge passage is open to purge evaporated fuel from the adsorption canister into the intake passage. The air-fuel ratio sensor detects the air-fuel ratio of the mixture supplied to the engine through the intake passage.

[0016] In this way, in the present disclosure, it is possible to perform leak diagnosis of the evaporated fuel processing device while taking into account a malfunction of the leak diagnosis device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above-mentioned and other objects, features and advantages of the present disclosure will become more apparent through reference to the accompanying drawings and the following detailed description.

[0018] Figure 1 This is an overall structural diagram of the evaporated fuel treatment device and the leak diagnosis device.

[0019] Figure 2 This is a flowchart of leakage diagnosis in a comparative example.

[0020] Figure 3 This is a flowchart (1) of the fault diagnosis performed by the fault diagnosis device of the first embodiment.

[0021] Figure 4 This is a flowchart (2) of the fault diagnosis performed by the fault diagnosis device of the first embodiment.

[0022] Figure 5 This is a timing diagram when there is no small leak in the system and no LCM failure.

[0023] Figure 6 This is a timing diagram when there is a small leak in the system.

[0024] Figure 7 This is a timing diagram when the second vent valve is stuck in the open position.

[0025] Figure 8 This is a timing diagram for a situation where the pump cannot be shut off.

[0026] Figure 9 This is a timing diagram when the filter is clogged.

[0027] Figure 10 This is a timing diagram in the case of a pump failure.

[0028] Figure 11 This is a timing diagram when there is a large leak in the system.

[0029] Figure 12 This is a timing diagram when the first vent valve is stuck in the open position.

[0030] Figure 13 This is a flowchart (1) of the fault diagnosis performed by the fault diagnosis device of the second embodiment.

[0031] Figure 14 This is a flowchart (2) of the fault diagnosis performed by the fault diagnosis device of the second embodiment.

[0032] Figure 15 This is a timing diagram when there is no small leak in the system and no LCM failure.

[0033] Figure 16 This is a timing diagram when there is a small leak in the system.

[0034] Figure 17 This is a timing diagram when the second vent valve is stuck in the open position.

[0035] Figure 18 This is a timing diagram for a situation where the pump cannot be shut off.

[0036] Figure 19 This is a timing diagram in the case of a pump failure.

[0037] Figure 20 This is a timing diagram when the filter is clogged.

[0038] Figure 21 This is a timing diagram when there is a large leak in the system.

[0039] Figure 22 This is a timing diagram when the first vent valve is stuck in the open position.

[0040] Figure 23 This is a flowchart of fault diagnosis performed by the fault diagnosis device according to the third embodiment.

[0041] Figure 24 This is a timing chart when filter A is clogged.

[0042] Figure 25 This is a timing diagram when the first vent valve is stuck in the open position.

[0043] Figure 26 This is a timing diagram when the filter BorC is clogged.

[0044] Figure 27 This is a timing diagram when the second vent valve is stuck in the open position.

[0045] Figure 28 This is a timing diagram in the case of a pump failure.

[0046] Figure 29 This is a timing diagram for a situation where the pump cannot be shut off. DETAILED DESCRIPTION

[0047] Several embodiments of a fault diagnosis device are described below with reference to the accompanying drawings. This fault diagnosis device diagnoses faults in a leak diagnosis device for diagnosing leaks in a vehicle's evaporated fuel treatment system, which uses an adsorption canister to recover fuel evaporated from a fuel tank and supply it to the intake passage. Hereinafter, the evaporated fuel treatment system will also be referred to as a "system." Furthermore, the leak diagnosis device will also be referred to as a "leak check module (LCM)."

[0048] [Overall Structure of Evaporative Fuel Treatment System and Leak Diagnosis System]

[0049] First, refer to Figure 1 The overall structure of the device will be described. The evaporated fuel processing device 10 includes a fuel tank 21, a vapor passage 20, an adsorption canister 23, an atmosphere passage 30, and a purge passage 40.

[0050] The fuel tank 21 storing the fuel is connected to the adsorption canister 23 for adsorbing the evaporated fuel via the vapor passage 20. Figure 1 In the configuration example, a sealing valve 22 is provided in the vapor passage 20. In principle, the sealing valve 22 isolates the fuel tank 21 from the canister 23 except during refueling, thereby sealing the fuel tank 21. However, a configuration without the sealing valve 22 is also possible.

[0051] The atmospheric passage 30 connects the canister 23 to the atmospheric opening 33. The purge passage 40 connects the canister 23 to the intake passage 45. A purge valve 42 is provided midway along the purge passage 40. When the purge valve 42 is open, evaporated fuel adsorbed by the canister 23 is purified along with air introduced through the atmospheric passage 30 through the purge passage 40 and then transported to the intake passage 45.

[0052] In this manner, evaporated fuel treatment device 10 purifies evaporated fuel adsorbed by adsorption canister 23 into intake passage 45 via purge passage 40. The amount of evaporated fuel purged is adjusted by the opening of purge valve 42. The mixed gas formed by the intake air and evaporated fuel in intake passage 45 is supplied to engine 50.

[0053] The leak diagnostic device 60 is installed in the atmosphere passage 30 of the evaporated fuel treatment device 10 to diagnose evaporated fuel leaks. Two parallel passages forming the atmosphere passage 30 are formed within the leak diagnostic device 60. The first atmosphere passage 31 serves as the main passage of the atmosphere passage 30, connecting the adsorption canister 23 and the atmosphere opening 33. The second atmosphere passage 32 serves as a bypass passage of the first atmosphere passage 31, connecting the adsorption canister 23 and the atmosphere opening 33. The confluence of the first atmosphere passage 31 and the second atmosphere passage 32 on the adsorption canister 23 side is denoted by Yc, and the confluence on the atmosphere opening 33 side is denoted by Ya.

[0054] The leakage diagnosis device 60 includes a first vent valve 61, a second vent valve 67, a pump 62, and filters 641, 642, and 643. The first vent valve 61 can block the first atmosphere passage 31. The second vent valve 67 can block the second atmosphere passage 32. In this embodiment, the first vent valve 61 and the second vent valve 67 are normally open solenoid valves.

[0055] The pump 62 is an electrically powered pump located in the second atmospheric passage 32, closer to the atmospheric opening 33 than the second vent valve 67. The pump 62 of this embodiment is a pressure-reducing pump capable of reducing the pressure of the second atmospheric passage 32 relative to atmospheric pressure toward the negative pressure side during operation. Alternatively, as described in other embodiments, a pressure-increasing pump capable of increasing the pressure of the second atmospheric passage 32 relative to atmospheric pressure toward the positive pressure side may be used.

[0056] Filter A641 is provided in the atmosphere passage 30 between the confluence point Ya on the atmosphere opening 33 side and the atmosphere opening 33. In the second atmosphere passage 32, filter B642 is provided between the second vent valve 67 and the confluence point Yc on the adsorption canister 23 side, and filter C643 is provided between the pump 62 and the confluence point Ya on the atmosphere opening 33 side.

[0057] In addition, generally, a pressure sensor 13 for detecting the pressure of a passage connected to the canister 23 is provided as a sensor used by the leakage diagnosis device 60 for leakage diagnosis. Figure 1In the configuration example, the pressure sensor 13 is provided in the atmospheric passage 30 between the junction Yc on the adsorption canister 23 side and the adsorption canister 23. Alternatively, the pressure sensor 13 may be provided in the first atmospheric passage 31 between the junction Yc and the first vent valve 61, or in the second atmospheric passage 32 between the junction Yc and the filter B642. Alternatively, the pressure sensor 13 may be provided in the vapor passage 20 between the sealing valve 22 and the adsorption canister 23.

[0058] Furthermore, normally, for engine control, an air-fuel ratio sensor (oxygen sensor: lambda sensor) 15 for detecting the air-fuel ratio of the mixed gas supplied to the engine 50 through the intake device 45 is provided on the exhaust side of the engine 50 .

[0059] The evaporated fuel treatment device 10 of such a structure is disclosed in Patent Document 1 (US2019 / 0368447A1). The leakage diagnosis method of the comparative example obtained by referring to claims 8 and 9 of Patent Document 1 is described in the following. Figure 2 Hereinafter, in the description of the flowchart, the symbol "S" represents a step. Figure 2 At the beginning of the step, the purge valve 42 is closed.

[0060] In S91, the first vent valve 61, which corresponds to the CVV in Patent Document 1, is closed. In S92, the second vent valve 67, which corresponds to the CVV check valve in Patent Document 1, is opened. In S93, the pump 62 is turned on (started, the same below), and after pressure is generated in the system, the pump 62 is turned off (closed, the same below) in S94. In S95, the second vent valve 67 is closed. In S96, it is determined whether the pressure in the monitored system is being maintained. If the pressure is maintained and the answer in S96 is yes, it is determined in S97 that "there is no leakage in the system." If the pressure is not maintained and the answer in S96 is no, it is determined in S98 that "there is leakage in the system."

[0061] However, the prior art of Patent Document 1 assumes that the leak diagnosis device 60 is not faulty. In other words, it fails to consider the possibility of failure of the various components of the leak diagnosis device 60. Therefore, if the leak diagnosis device 60 fails, it is impossible to distinguish whether the "leak present" result in the leak diagnosis is due to a leak in the evaporated fuel processing device 10 or a failure in the leak diagnosis device 60. To address this issue, the fault diagnosis device 80 of this embodiment is capable of diagnosing a failure in the leak diagnosis device 60.

[0062] The fault diagnosis device 80 of the present embodiment performs fault diagnosis of the leak diagnosis device 60 based on one or more parameters among (1) the output value Psns of the pressure sensor 13, (2) the current value Ipump 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 will be referred to as "pressure sensor output value Psns," the current value Ipump of the pump 62 will be referred to as "pump current Ipump," and the output value A / F of the air-fuel ratio sensor 15 will be referred to as "air-fuel ratio sensor output value A / F."

[0063] 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 Ipump. In the third embodiment, fault diagnosis is performed based on the air-fuel ratio sensor output value A / F. Figure 1 As indicated by the dotted arrows, the fault diagnosis device 80 does not always need to obtain the three parameters, and may only obtain the parameters to be used according to the embodiment.

[0064] [Fault diagnosis of leak diagnosis device]

[0065] Next, the fault diagnosis performed by the fault diagnosis device 80 on the leakage diagnosis device 60 will be described based on flowcharts and sequence diagrams according to the embodiment. The first and second embodiments share portions of the flowcharts, and substantially identical steps are assigned the same step numbers. Furthermore, the flowcharts of the first and second embodiments are shown across the two figures using connector symbols J1 and J2, respectively. The step numbers of some of the numbered determination steps correspond to the symbols of the faulty components.

[0066] Fault diagnosis is performed while the vehicle is parked, for example, after a few hours have passed since the ignition was turned off. In the first and second embodiments, system leak diagnosis is performed simultaneously with fault diagnosis by the leak diagnosis device ("LCM" in the figures) 60. As a rough guideline, a "large leak" in the system refers to a leak equal to or greater than the flow rate when the first vent valve 61 is open, presumably due to a valve not closing or a disconnected piping connection. On the other hand, a "small leak" refers to a minute leak caused by, for example, a blowhole.

[0067] The timing diagrams commonly show the ON / OFF states of the purge valve 42, first vent valve 61, second vent valve 67, and pump 62. For the normally closed purge valve 42, "ON" indicates open, and "OFF" indicates closed. For the normally open first vent valve 61 and second vent valve 67, "ON" indicates closed, and "OFF" indicates open. In the first and second embodiments, the purge valve 42 is always closed.

[0068] The timing chart of the first embodiment shows the pressure sensor output value Psns, and some of the charts also show the system temperature, that is, the ambient temperature of the leak diagnostic device 60. This example illustrates a case where the system temperature rises relative to the initial temperature. The timing chart of the second embodiment shows the pump current Ipump and the pressure sensor output value Psns. In this embodiment, a pressure-reducing pump 62 is assumed. Therefore, when the pump 62 operates normally, the pressure sensor output value Psns changes from atmospheric pressure to the negative side. The timing chart of the third embodiment shows the air-fuel ratio sensor output value A / F.

[0069] The following description will be made with reference to both the flowchart and the timing diagram. The figure numbers marked in brackets in the steps of the flowchart represent the figure numbers of the corresponding timing diagrams. In addition, in each step, the main body that turns the pump 62 and the vent valves 61 and 67 on / off is the fault diagnosis device 80, but if the subject is recorded in the form of "the fault diagnosis device 80 turns the pump 62 on (starts)" each time, it will become redundant. Therefore, basically, the pump 62 and the vent valves 61 and 67 are recorded as the subject in the form of "the pump 62 is set to start" and the passive state.

[0070] <First embodiment>

[0071] Reference Figures 3 to 12 The fault diagnosis of the first embodiment is described below. The relationship between the following pressure thresholds is "PE>atmospheric pressure>PC>PA>PB", "atmospheric pressure>PF>PA". Figure 3 At the start of the step, the purge valve 42 is closed. At time t1, the first vent valve 61 is closed in S11, and the pump 62 is activated in S12. If the leak diagnostic device 60 is functioning normally, the first atmosphere passage 31 is blocked, allowing air to flow from the adsorption canister 23 to the atmosphere opening 33 via the second atmosphere passage 32.

[0072] At time t2, in S13, it is determined whether the pressure sensor output value Psns is below the threshold value PA. Figures 5 to 8 If the pressure sensor output value Psns is below the threshold PA, the result is YES in S13 and the pump 62 is turned OFF in S14. If NO in S13, the result is YES in S60 and the first vent valve is stuck open or the pump is faulty or the filter is clogged or there is a large leak in the system. Figure 4 .

[0073] In S15 following S14, it is determined whether the pressure sensor output value Psns is greater than or equal to the threshold value PB. If so, the second vent valve 67 is closed in S16. Here, a waiting time for the determination in S15 may be provided between the pump shutoff in S14 and the closing of the second vent valve in S16, but Figures 5 to 7 For convenience, the pump is turned off and the second vent valve is closed at the same time t2. According to S14 and S16, if the system and the leakage diagnosis device 60 are normal, the second atmosphere passage 32 is cut off to maintain the pressure in the system.

[0074] In S17, it is determined whether the time from the closing of the second vent valve 67 to the pressure sensor output value Psns reaching the threshold value PC is greater than the threshold value TQ. That is, the pressure sensor output value Psns at time t3 after the threshold value TQ has passed since time t2 is compared with the threshold value PC. Figure 5 As shown, if the pressure sensor output value Psns at time t3 is smaller than the threshold value PC and the result in S17 is YES, it is determined in S70 that "there is no small leak in the system and no fault in the LCM." If the result in S17 is NO, it is determined in S678 that "the second vent valve is stuck in the open position or there is a small leak in the system." Figure 6 、 Figure 7 As shown, at time t4, the pump 62 is set to start in S18.

[0075] In S19, it is determined whether the pressure sensor output value Psns is greater than the threshold value PA after the pump 62 is set to start. Figure 6 As shown in FIG, if the pressure sensor output value Psns does not drop to the threshold value PA, then the judgment in S19 is yes, and it is determined in S68 that "a small leak exists in the system". Figure 7 As shown, if the pressure sensor output value Psns drops to the threshold value PA, a negative determination is made in S19 , and it is determined in S67 that “the second vent valve is stuck in the open position”.

[0076] Return to S15, as Figure 8 As shown, if the pressure sensor output value Psns continues to decrease and falls below the threshold value PB after the pump OFF command, it is determined in S66 that "the pump cannot be turned off."

[0077] Next, refer to Figure 4. After the judgment is negative in S13, the pump 62 is set to off in S14. At this time, the second vent valve 67 is opened. In S21, the pressure sensor output value Psns when the ambient temperature of the leakage diagnosis device 60 changes (increases here) is confirmed. Here, the system temperature can be actively heated by a heating device or the like, or it can be left to rise naturally as the daytime temperature rises. If the temperature rises while the system is closed, the air in the piping will expand and the pressure will rise. Therefore, the pressure sensor output value Psns changes along with the system temperature change.

[0078] exist Figure 9 In the example, 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 above the threshold value PE. The threshold value PE can also be set at any time according to the system temperature after the rise. Figure 9 As shown, in the case of YES in S22 , it is determined that “the filter is clogged” in S64 .

[0079] For ease of explanation, the following steps and time are repeated for the case where the answer in S22 is "No," meaning the filter is not clogged. In S23, at time t2, simultaneously with the pump 62 being turned off in S14, the second vent valve 67 is closed. Then, in S24, similar to S21, the pressure sensor output value Psns is checked when the ambient temperature of the leak diagnostic device 60 changes.

[0080] exist Figures 10 to 12 In the example, from time t2 to time t7, the system temperature rises while the second vent valve 67 is closed. In S25, similarly to S22, it is determined whether the pressure sensor output value Psns after the temperature rise is greater than the threshold value PE. Figure 10 As shown, if the answer is YES in S25, it is estimated that the second vent valve 67 is normally closed. Then, in S62, it is determined that the main reason for the NO answer in S13 is "pump failure."

[0081] If the answer in S25 is "No," at time t7, the second vent valve 67 is opened in S27 and the pump 62 is activated in S28. In S29, a determination is made as to whether the time from when the pump 62 was activated until the pressure sensor output value Psns reached the threshold value PF is greater than the threshold value TR. Specifically, the pressure sensor output value Psns at time t8, which is after the threshold value TR has passed since time t7, is compared with the threshold value PF.

[0082] like Figure 11As shown, if the pressure sensor output value Psns at time t8 is greater than the threshold value PF and the answer is YES in S29, a "large leak in the system" is determined in S65. If a large leak in the system exists, the pump 62 will draw in gas containing evaporated fuel, resulting in a greater pump load than when drawing in gas that does not contain evaporated fuel. This increases the time required to reduce the pressure in the pipe to the threshold value PF.

[0083] like Figure 12 As shown, if the pressure sensor output value Psns at time t8 is less than the threshold value PF and the result in S29 is NO, it is determined in S66 that the "first vent valve is stuck in the open position." When the first vent valve 61 is stuck in the open position, the pump 62 draws gas that does not contain evaporated fuel, resulting in a small pump load and a short time for the pressure in the pipe to drop to the threshold value PF.

[0084] As described above, the fault diagnosis of the first embodiment includes the step of evaluating the pressure sensor output value Psns with the first vent valve 61 closed, the second vent valve 67 open, and the pump 62 activated. 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.

[0085] The fault diagnosis of the first embodiment also includes a step of evaluating a change in the pressure sensor output value Psns immediately after the second vent valve 67 is closed from an open state. 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.

[0086] The fault diagnosis of the first embodiment also includes a step of evaluating changes in the pressure sensor output value Psns immediately after the pump 62 is started from the off state, with the first vent valve 61 closed and the second vent valve 67 open. S29 corresponds to this step. The specific method for evaluating changes in the pressure sensor output value Psns is the same as described above.

[0087] The fault diagnosis of the first embodiment further includes a step of evaluating the pressure sensor output value Psns when the ambient temperature of the leakage diagnosis device 60 changes while the first vent valve 61 is closed, the second vent valve 67 is open, and the pump 62 is turned off. S22 and S25 correspond to this step.

[0088] The fault diagnosis device 80 of the first embodiment combines the above steps to perform various fault diagnoses of the leak diagnosis device 60. This allows for appropriate discrimination between a leak in the evaporated fuel processing device 10 and a fault in the leak diagnosis device 60.

[0089] (Second embodiment)

[0090] Reference Figures 13 to 22 The fault diagnosis of the second embodiment will be described below. Note that any overlap with the first embodiment will be omitted as appropriate. S11 to S14 are the same as those of the first embodiment. When the pump 62 is activated at times t1 to t2, if the leak diagnosis device 60 is functioning normally, the pump current Ipump reaches the reference value I0. The following pump current thresholds are related by "IH > I0 > IG (>0)" and "IK > IL > I0 > IM."

[0091] After the pump 62 is turned off in S14, it is determined in S31 whether the pump current Ipump is below a threshold value IG close to 0. If so, the second vent valve 67 is closed in S16. Here, a waiting time for the determination in S31 may be set between the pump turning off in S14 and the closing of the second vent valve in S16, but Figures 15 to 17 In FIG. 1 , for convenience, the pump closing and the second vent valve closing are recorded at the same time t2.

[0092] S17 is the same as the first embodiment, such as Figure 15 As shown, if the answer is YES in S17, it is determined in S70 that “there is no small leak in the system and no failure in the LCM.” If the answer is NO in S17, S678 and S18 are the same as those in the first embodiment.

[0093] In S32, it is determined whether the pump current Ipump is greater than the threshold value IH after the pump 62 is set to start. Figure 16 As shown in FIG, if the pump current Ipump is greater than the threshold value IH, then the judgment in S32 is yes, and in S68 it is judged that "there is a small leak in the system". Figure 17 As shown, if the pump current Ipump is equal to or less than the threshold value IH, a negative determination is made in S32 and a determination is made in S67 that "the second vent valve is stuck in the open position."

[0094] Return to S31, as Figure 18 As shown, when the pump current Ipump is larger than the threshold value IG after the pump OFF command, it is determined as NO in S31 and it is determined as "the pump cannot be OFF" in S66.

[0095] Next, refer to Figure 14 After the judgment in S13 is no, in S33, it is judged whether the pump current Ipump is greater than the threshold value IK or is 0. Figure 19 As shown, if the answer is yes in S33, it is determined in S62 that "pump failure" is the case. If the answer is no in S33, it is determined in S34 whether the pump current Ipump is greater than the threshold IL and less than the threshold IK. Figure 20 As shown, in the case of YES in S34 , it is determined that “the filter is clogged” in S64 .

[0096] If the answer is NO in S34, then in S36, it is determined whether the pump current Ipump is greater than the threshold value IM and less than the threshold value IL. Figure 21 As shown, if the answer is yes in S36, it is determined in S65 that "there is a large leak in the system". Figure 22 As shown, when the pump current Ipump is equal to or less than the threshold value IM and the answer is NO in S36 , it is determined in S61 that “the first vent valve is stuck in the open position”.

[0097] As described above, the fault diagnosis device 80 of the second embodiment diagnoses at least a fault in the pump 62 based on the pump current Ipump when the first vent valve 61 is closed, the second vent valve 67 is open, and the pump 62 is activated, or when the pump 62 is activated and then turned off. S33, S34, and S36 correspond to fault diagnosis when the pump 62 is activated, while S31 corresponds to fault diagnosis when the pump 62 is activated and then turned off.

[0098] Furthermore, the fault diagnosis device 80 of the second embodiment combines fault diagnosis with a determination based on the pressure sensor output value Psns. This allows the leak diagnosis device 60 to perform multiple types of fault diagnosis. This allows for appropriate differentiation between a leak in the evaporated fuel processing device 10 and a fault in the leak diagnosis device 60.

[0099] (Third embodiment)

[0100] Reference Figures 23 to 29 The fault diagnosis of the third embodiment will now be described. The fault diagnosis device 80 of the third embodiment performs fault diagnosis based on the output value of the air-fuel ratio sensor 15 while the purge valve 42 is open and evaporated fuel is being purged from the adsorption canister 23 to the intake passage 45. Unlike the first and second embodiments, the third embodiment does not simultaneously perform system leak diagnosis; instead, only the leak diagnosis device 60 performs fault diagnosis. Furthermore, after confirming that the leak diagnosis device 60 is not faulty, the system leak diagnosis using the leak diagnosis device 60 is re-performed.

[0101] In the horizontal axis of the timing chart of the third embodiment, time is represented by τ1 to τ5 to distinguish it from the first and second embodiments. The double-dashed ellipse in the figure indicates the area of ​​interest. The relationship between the air-fuel ratio thresholds is "λA>λB>λC>14.7 (ideal value)."

[0102] At time τ1, the purge valve 42 is opened in S41 to perform purge. If the passage from the atmosphere opening 33 to the purge valve 42 can be ventilated normally, the evaporated fuel is introduced into the intake passage 45 by the start of purge, and the air-fuel ratio A / F of the mixture becomes the ideal value of 14.7. If the passage is clogged, it is difficult for the evaporated fuel to be introduced into the intake passage 45, so the 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 below the threshold value λA. Figure 24 As shown, if the air-fuel ratio sensor output value A / F is larger than the threshold value λA, the determination in S42 is NO, and it is determined in S641 that "the filter A is clogged."

[0103] If the answer is yes in S42, at time τ2, after the first vent valve 61 is closed in S43, it is determined in S44 whether the air-fuel ratio sensor output value A / F is greater than the threshold value λB. Figure 25 As shown, if the air-fuel ratio sensor output value A / F is equal to or less than the threshold value λB, a negative determination is made in S44 , and it is determined in S61 that “the first vent valve is stuck in the open position”.

[0104] If the answer is yes in S44, then in S45, it is determined whether the air-fuel ratio sensor output value A / F is less than the threshold value λA. Figure 26 As shown, if the air-fuel ratio sensor output value A / F is greater than the threshold λA, the determination in S45 is NO, and in S642 it is determined that "filter B or C is clogged." That is, it is determined that at least one of the filter B642 or the filter C643 in the second atmosphere passage 32 is clogged.

[0105] If the answer is yes in S45, at time τ3, after the second vent valve 67 is closed in S46, it is determined in S47 whether the air-fuel ratio sensor output value A / F is greater than the threshold value λA. Figure 27 As shown, if the air-fuel ratio sensor output value A / F is equal to or less than the threshold value λA, a negative determination is made in S47 , and it is determined in S67 that “the second vent valve is stuck in the open position”.

[0106] If the answer is yes in S47, at time τ4, the second vent valve 67 is opened in S48, and the pump 62 is set to start in S49. If the pump 62 is normal, the evaporated fuel is sucked toward the atmosphere opening 33, which hinders the introduction of the evaporated fuel into the intake passage 45, and 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 value λC. Figure 28 As shown, if the air-fuel ratio sensor output value A / F is equal to or less than the threshold value λC, a NO determination is made in S50 and a "pump failure" determination is made in S62.

[0107] If the answer is yes in S50, at time τ5, the pump 62 is turned off in S51. If the pump 62 stops normally, the suction of the evaporated fuel is stopped, 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 below the threshold value λC. Figure 29 As shown, if the air-fuel ratio sensor output value A / F is greater than the threshold value λC, a negative determination is made in S52 , and a determination is made in S66 that “the pump cannot be turned off”.

[0108] In summary, the fault diagnosis of the third embodiment includes the step of evaluating the output value of the air-fuel ratio sensor in one or more of the following conditions (1) to (4). Thus, the fault diagnosis device 80 can perform fault diagnosis of the leak diagnosis device 60 based on the air-fuel ratio sensor output value A / F. This allows for appropriate discrimination between a leak in the evaporated fuel processing device 10 and a fault in the leak diagnosis device 60.

[0109] (1) The first vent valve 61 and the second vent valve 67 are opened and the pump 62 is turned off. S42 corresponds to this.

[0110] (2) Close the first vent valve 61 and the second vent valve 67 and set the pump 62 to an off state. S47 corresponds to this.

[0111] (3) Close the first vent valve 61, open the second vent valve 67, and turn off the pump 62. S44, S45, and S52 correspond to this.

[0112] (4) The first vent valve 61 is closed, the second vent valve 67 is opened, and the pump 62 is activated. S50 corresponds to this.

[0113] (Other Embodiments)

[0114] (a) As described above, the pump 62 of the leak diagnostic device 60 can also be a pressure pump that, during operation, pressurizes the second atmospheric passage 32 toward the positive pressure side relative to atmospheric pressure. In this case, the magnitude of the pressure sensor output value Psns relative to atmospheric pressure in the first and second embodiments is essentially reversed. Therefore, by using the absolute value of the pressure sensor output value Psns relative to atmospheric pressure (i.e., 0), it is possible to express the pressure fluctuations caused by both the pressure reducing pump and the pressure increasing pump.

[0115] (b) The fault diagnosis in the first and second embodiments does not necessarily have to be performed with the purge valve 42 always closed. As long as the system pressure can be detected, the fault diagnosis can be performed with the purge valve 42 open.

[0116] (c) The pressure change during "temperature change" in S21 and S24 of the first embodiment is not limited to a pressure increase during temperature rise; a pressure decrease during temperature drop may also be confirmed. In this case, in addition to forced cooling using a fan or the like, the system temperature drop after engine stop may be utilized, or the system temperature may be allowed to decrease naturally as the nighttime temperature drops.

[0117] (d) In the step of evaluating a change in pressure sensor output value Psns caused by a certain operation, comparing the time required for pressure sensor output value Psns to reach a predetermined pressure threshold with a predetermined time threshold corresponds to evaluation based on average velocity. Alternatively, the change can be evaluated using, for example, instantaneous velocity calculated from the difference in pressure sensor output value Psns within a short period of time immediately after the operation.

[0118] (e) The order of the steps in the flowcharts of the above-described embodiments is merely an example. The order of the steps may be modified as appropriate as long as fault diagnosis is possible. Furthermore, some steps may be omitted, for example, if a component of the leak diagnostic device 60 is known to be functioning normally.

[0119] The present disclosure is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit and scope of the present disclosure.

[0120] The present disclosure is described based on the embodiments. However, the present disclosure is not limited to these embodiments and structures. The present disclosure also includes various modifications and variations within the scope of the equivalent. In addition, various combinations and forms, and further combinations and forms including only one element, more than or less than these elements, also fall within the scope and scope of the present disclosure.

Claims

1. A fault diagnosis device for a leak diagnosis device, the fault diagnosis device being configured to diagnose a fault in the leak diagnosis device, the leak diagnosis device being provided in an atmosphere passage of an evaporated fuel treatment device to diagnose a leak of evaporated fuel, the evaporated fuel treatment device purifying evaporated fuel adsorbed in an adsorption canister connected to a fuel tank via a vapor passage and to an atmosphere opening via the atmosphere passage into an intake passage via a purge passage, the fault diagnosis device being characterized in that: The leakage diagnosis device comprises: a first vent valve capable of shutting off a first atmospheric passage serving as a main passage of the atmospheric passage and connecting the adsorption canister and the atmospheric opening; a second vent valve capable of shutting off a second atmospheric passage serving as a bypass passage of the first atmospheric passage to connect the canister and the atmospheric opening; and a pump provided in the second atmospheric passage at a position closer to the atmospheric opening than the second vent valve, capable of pressurizing or depressurizing the second atmospheric passage; In the fault diagnosis, Fault diagnosis is performed based on an output value of a pressure sensor that detects the pressure of a passage connected to the adsorption canister. The fault diagnosis includes the step of evaluating the output value of the pressure sensor in a state where the first vent valve is closed, the second vent valve is opened, and the pump is activated.

2. The fault diagnosis device of the leakage diagnosis device according to claim 1, wherein: The fault diagnosis further includes the step of evaluating a change in the output value of the pressure sensor immediately after the second vent valve is closed from an open state.

3. The fault diagnosis device of the leakage diagnosis device according to claim 1 or 2, wherein: The fault diagnosis further includes the step of evaluating a change in the output value of the pressure sensor from when the pump is turned off to immediately after it is started, with the first vent valve closed and the second vent valve open.

4. The fault diagnosis device of the leakage diagnosis device according to claim 1 or 2, wherein: The fault diagnosis further includes the step of evaluating an output value of the pressure sensor when the ambient temperature of the leakage diagnosis device changes while the first vent valve is closed, the second vent valve is open, and the pump is turned off.

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