阅读说明：本技术 蒸发燃料处理装置 (Evaporated fuel treatment device ) 是由 浅沼大作 于 2019-11-25 设计创作，主要内容包括：在蒸发燃料处理装置中,具有异常判定部,所述异常判定部用于判定吹扫通路的异常,所述异常判定部一边维持根据内燃机的运转状态设定的吹扫控制阀的占空比,一边将所述吹扫控制阀的驱动周期变更为比初始设定值长的周期、并且基于第一变动幅度及第二变动幅度来判定所述吹扫通路的异常,所述第一变动幅度是根据在变更所述驱动周期之前由空气流量计检测到的检测值来计算出的,所述第二变动幅度是根据在变更所述驱动周期之后由空气流量计检测到的检测值来计算出的。(The evaporative fuel processing device includes an abnormality determination unit for determining an abnormality in the purge passage, wherein the abnormality determination unit changes the drive cycle of the purge control valve to a cycle longer than an initial set value while maintaining a duty ratio of the purge control valve set according to an operating state of the internal combustion engine, and determines the abnormality in the purge passage based on a first fluctuation range calculated based on a detection value detected by an airflow meter before the drive cycle is changed and a second fluctuation range calculated based on a detection value detected by the airflow meter after the drive cycle is changed.)

1. An evaporated fuel processing apparatus comprising:

an air flow meter provided in an intake passage connected to the internal combustion engine; a vapor passage connected to the fuel tank; a canister that stores evaporated fuel delivered from the fuel tank via the vapor passage; a purge passage connected to the intake passage and the canister; a purge pump provided in the purge passage; and a purge control valve provided on a downstream side of the purge pump,

the evaporated fuel treatment apparatus is characterized in that,

an abnormality determination unit for determining abnormality of the purge passage,

the abnormality determination unit changes the drive cycle of the purge control valve to a cycle longer than an initial set value while maintaining the duty ratio of the purge control valve set according to the operating state of the internal combustion engine, and determines an abnormality of the purge passage based on a first fluctuation range calculated based on a detection value detected by the airflow meter before the drive cycle is changed and a second fluctuation range calculated based on a detection value detected by the airflow meter after the drive cycle is changed.

2. The evaporated fuel treatment apparatus according to claim 1,

the abnormality determination unit calculates the first fluctuation range before the drive cycle is changed, based on a detection value detected by the airflow meter when the purge control valve is opened or closed.

3. The evaporated fuel treatment apparatus according to claim 1 or 2,

the abnormality determination unit sets a guard value for the duty ratio of the purge control valve, sets the drive period to be 1.5 to 2.5 times as long as the initial set value, and calculates the second fluctuation range after the drive period is changed, based on a detection value detected by the airflow meter.

4. The evaporated fuel treatment apparatus according to claim 1,

the abnormality determination unit determines that there is an abnormality in the purge passage when a difference between the second variation width and the first variation width is smaller than a first determination value.

5. The evaporated fuel treatment apparatus according to claim 1,

the abnormality determination unit determines that there is an abnormality in the purge passage when a value obtained by dividing the second fluctuation range by the first fluctuation range is smaller than a second determination value.

6. The evaporated fuel treatment apparatus according to claim 4 or 5,

the abnormality determination unit determines the first determination value or the second determination value based on a duty ratio of the purge control valve and a rotation speed of the purge pump.

7. An evaporated fuel processing apparatus comprising:

an air flow meter provided in an intake passage connected to the internal combustion engine; a vapor passage connected to the fuel tank; a canister that stores evaporated fuel delivered from the fuel tank via the vapor passage; a purge passage connected to the intake passage and the canister; a purge pump provided in the purge passage; and a purge control valve provided on a downstream side of the purge pump,

the evaporated fuel treatment apparatus is characterized in that,

an abnormality determination unit for determining abnormality of the purge passage,

the abnormality determination unit determines an abnormality of the purge passage based on a difference between a variation cycle of a detection value detected by the airflow meter and a drive cycle of the purge control valve while maintaining a duty ratio of the purge control valve set according to an operating state of the internal combustion engine.

8. The evaporated fuel treatment apparatus according to claim 7,

as the variation period, an average value of the variation period within a predetermined time is used.

Technical Field

The present disclosure relates to an evaporated fuel treatment apparatus that supplies evaporated fuel generated in a fuel tank to an internal combustion engine and treats the evaporated fuel.

Background

In the evaporated fuel treatment apparatus, when an abnormality such as clogging or leakage occurs in the passage, the evaporated fuel is released into the outside air. Therefore, in order to detect the occurrence of such a situation, it is required to determine an abnormality of the passage.

As an evaporated fuel treatment device for determining such a passage abnormality, for example, there is a device described in patent document 1. The evaporated fuel processing device determines an abnormality of the purge passage based on a change in a detection value of the air flow meter when a duty ratio of a purge control valve disposed in the purge passage is changed. In the evaporated fuel treatment device described in patent document 2, an abnormality determination (leak detection) is performed on the purge passage based on a change in a detection value of the air flow meter when the purge pump is driven after a shutdown.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-141438

Patent document 2: japanese patent laid-open publication No. 2017-129073

Disclosure of Invention

Problems to be solved by the invention

However, in the evaporated fuel treatment device described in patent document 1, since the duty ratio of the purge control valve is changed when abnormality determination is performed, the purge control valve cannot be controlled at a duty ratio according to the operating state of the engine. Therefore, fluctuation in the air-fuel ratio (a/F) may occur to deteriorate the accuracy of abnormality detection for the purge passage. On the other hand, in the evaporated fuel treatment device described in patent document 2, since the purge pump is driven only for abnormality detection of the purge passage, the fuel consumption rate is deteriorated, and if a leak occurs in the purge passage, the evaporated fuel may be released to the outside air.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide an evaporated fuel treatment apparatus capable of accurately determining an abnormality in a purge passage and suppressing deterioration of a fuel consumption rate and release of evaporated fuel to outside air.

Means for solving the problems

One aspect of the present disclosure made to solve the above problems is an evaporated fuel treatment apparatus including:

an air flow meter provided in an intake passage connected to the internal combustion engine; a vapor passage connected to the fuel tank; a canister that stores evaporated fuel delivered from the fuel tank via the vapor passage; a purge passage connected to the intake passage and the canister; a purge pump provided in the purge passage; and a purge control valve provided on a downstream side of the purge pump,

the evaporated fuel treatment device includes an abnormality determination unit configured to determine an abnormality of the purge passage,

the abnormality determination unit changes the drive cycle of the purge control valve to a cycle longer than an initial set value while maintaining the duty ratio of the purge control valve set according to the operating state of the internal combustion engine, and determines an abnormality of the purge passage based on a first fluctuation range calculated based on a detection value detected by the airflow meter before the drive cycle is changed and a second fluctuation range calculated based on a detection value detected by the airflow meter after the drive cycle is changed.

When the drive cycle of the purge control valve is made longer, the time during which the purge control valve is opened becomes longer, so if the purge passage is normal, the purge gas flowing into the intake passage increases compared to the case of the initially set drive cycle. As a result, the amount of air flowing into the intake passage is reduced by the amount of purge gas increase. Therefore, the second fluctuation range is larger than the first fluctuation range with respect to the fluctuation range calculated from the detection value detected by the air flow meter. On the other hand, when there is an abnormality such as leakage or clogging in the purge passage, the purge gas hardly flows into the intake passage, and therefore the amount of air flowing into the intake passage also hardly changes. Therefore, the fluctuation range calculated from the detection value detected by the air flow meter does not change in the first fluctuation range and the second fluctuation range. Therefore, the abnormality of the purge passage can be determined based on the first variation range before the drive cycle is changed and the second variation range after the drive cycle is changed.

Specifically, in the above-described evaporated fuel treatment apparatus,

the abnormality determination unit may determine that there is an abnormality in the purge passage when a difference between the second variation width and the first variation width is smaller than a first determination value.

Alternatively, in the above-mentioned evaporated fuel treatment apparatus,

the abnormality determination unit may determine that there is an abnormality in the purge passage when a value obtained by dividing the second fluctuation range by the first fluctuation range is smaller than a second determination value.

In this evaporated fuel treatment device, since the abnormality of the purge passage is determined while the duty ratio of the purge control valve set according to the operating state of the internal combustion engine is maintained, the air-fuel ratio (a/F) fluctuation is less likely to occur. Therefore, the abnormality of the purge passage can be determined with high accuracy. Further, since the abnormality of the purge passage is determined in accordance with the original purge timing, it is possible to suppress deterioration of the fuel consumption rate and release of the evaporated fuel to the outside air.

In the above-described evaporated fuel treatment apparatus,

the abnormality determination unit may calculate the first fluctuation range before the drive cycle is changed, based on a detection value detected by the airflow meter when the purge control valve is opened or closed.

In this way, the first variation range can be obtained not only when the purge control valve is opened (during the purge operation), but also when the purge control valve is closed, that is, when the purge is turned off.

Further, in the above-mentioned evaporated fuel treatment apparatus,

the abnormality determination unit may set a guard value for the duty ratio of the purge control valve, set the drive cycle to be 1.5 to 2.5 times as long as the initial set value, and calculate the second fluctuation range after the drive cycle is changed based on a detection value detected by the airflow meter.

By obtaining the second fluctuation range in this way, the fluctuation range larger than the first fluctuation range is reliably obtained if the purge passage is normal. Therefore, erroneous determination of the abnormality of the purge passage can be suppressed, and therefore the abnormality of the purge passage can be determined with higher accuracy.

In addition, in the above-mentioned evaporated fuel treatment apparatus,

preferably, the abnormality determination unit determines the first determination value or the second determination value based on a duty ratio of the purge control valve and a rotation speed of the purge pump.

With this configuration, the first determination value and the second determination value are determined according to the state of purging, and therefore the accuracy of determining an abnormality in the purge passage can be improved.

Another aspect of the present disclosure made to solve the above problems is an evaporated fuel treatment apparatus including:

an air flow meter provided in an intake passage connected to the internal combustion engine; a vapor passage connected to the fuel tank; a canister that stores evaporated fuel delivered from the fuel tank via the vapor passage; a purge passage connected to the intake passage and the canister; a purge pump provided in the purge passage; and a purge control valve provided on a downstream side of the purge pump,

the evaporated fuel treatment device includes an abnormality determination unit configured to determine an abnormality of the purge passage,

the abnormality determination unit determines an abnormality of the purge passage based on a difference between a variation cycle of a detection value detected by the airflow meter and a drive cycle of the purge control valve while maintaining a duty ratio of the purge control valve set according to an operating state of the internal combustion engine.

When there is no abnormality of leakage or clogging in the purge passage and the purge passage is normal, the amount of air flowing into the intake passage changes in accordance with the opening/closing drive of the purge control valve. Therefore, the period of variation of the detection value detected by the air flow meter coincides with or approximates the drive period of the purge control valve. On the other hand, when there is an abnormality such as leakage or clogging in the purge passage, the purge gas hardly flows into the intake passage, and therefore the amount of air flowing into the intake passage does not change according to the opening/closing drive of the purge control valve. Therefore, a difference is generated between the fluctuation cycle of the detection value detected by the air flow meter and the drive cycle of the purge control valve. Therefore, it is possible to determine an abnormality of the purge passage based on a difference between a fluctuation cycle of the detection value detected by the air flow meter and a drive cycle of the purge control valve.

In this evaporated fuel treatment device, since the abnormality of the purge passage is determined while the duty ratio of the purge control valve set according to the operating state of the internal combustion engine is maintained, the air-fuel ratio (a/F) fluctuation is less likely to occur. Therefore, the abnormality of the purge passage can be determined with high accuracy. Further, since the abnormality of the purge passage is determined in accordance with the original purge timing, it is possible to suppress deterioration of the fuel consumption rate and release of the evaporated fuel to the outside air.

In addition, in the above-mentioned evaporated fuel treatment apparatus,

preferably, the variation period is an average value of the variation periods over a predetermined time.

Since the average value of the variation period within the predetermined time is used as the variation period in this way, it is possible to determine an abnormality in the purge passage while being less susceptible to the influence of the frequency change due to the external disturbance on the detection value detected by the air flow meter.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present disclosure, it is possible to provide an evaporated fuel treatment device capable of determining abnormality of a purge passage with high accuracy and suppressing deterioration of a fuel consumption rate and release of evaporated fuel to outside air.

Drawings

Fig. 1 is a schematic diagram showing an overall configuration of an engine system including an evaporated fuel treatment device.

Fig. 2 is a diagram showing a control flowchart of abnormality determination in the first embodiment.

Fig. 3 is a diagram showing an example of a map for determining a determination value.

Fig. 4 is a diagram showing an example of a map for determining a determination value in a modification.

Fig. 5 is a diagram showing an example of a control timing chart in the first embodiment.

Fig. 6 is a diagram showing a control flowchart of abnormality determination in the second embodiment.

Fig. 7 is a diagram showing an example of a control timing chart in the second embodiment.

Fig. 8 is a diagram showing a control flowchart of abnormality determination in the modification of the second embodiment.

Fig. 9 is an explanatory diagram of the cycle and the number of peaks of the peak value in the modification of the second embodiment.

Detailed Description

An evaporated fuel treatment apparatus according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, a case will be described in which the evaporated fuel treatment device of the present disclosure is applied to an engine system mounted on a vehicle such as an automobile.

< Overall Structure of System >

An engine system to which evaporated fuel processing apparatus 1 according to the present embodiment is applied is mounted on a vehicle such as an automobile, and includes engine ENG as shown in fig. 1. Engine ENG is connected to an intake passage IP for supplying air (intake air ) to engine ENG. The intake passage IP is provided with: an electronic throttle valve THR (throttle valve) for controlling the amount of air flowing into engine ENG (intake air amount) by opening and closing intake passage IP, and a supercharger TC for increasing the density of air flowing into engine ENG. An air cleaner AC for removing foreign matter from air flowing into the intake passage IP is provided in a portion of the intake passage IP on the upstream side of the electronic throttle valve THR (upstream side in the flow direction of the intake air). Accordingly, in intake passage IP, air passes through air cleaner AC and is drawn into engine ENG. Further, an air flow meter AFM is provided on the downstream side of the air cleaner AC. The air flow meter AFM detects the amount of air introduced from the atmosphere into the intake passage IP through the air cleaner AC. Then, the detection signal of the air flow meter AFM is input to the control unit 17 (abnormality determination unit 21) described later.

The evaporated fuel treatment apparatus 1 of the present embodiment is an apparatus for supplying evaporated fuel in a fuel tank FT to an engine ENG through an intake passage IP in such an engine system. The evaporated fuel treatment apparatus 1 includes an adsorption tank 11, a purge passage 12, a purge pump 13, a purge control valve 14, an atmosphere passage 15, a vapor passage 16, a control unit 17, a filter 18, an atmosphere shutoff valve 19, and the like.

The canister 11 is connected to the fuel tank FT via a vapor passage 16, and the canister 11 temporarily stores the evaporated fuel flowing from the inside of the fuel tank FT via the vapor passage 16. The canister 11 communicates with the purge passage 12 and the atmosphere passage 15.

The purge passage 12 is connected to the intake passage IP and the canister 11. Thereby, the purge gas (gas including the evaporated fuel) flowing out of the canister 11 flows through the purge passage 12 and is introduced into the intake passage IP. In the example shown in fig. 1, the purge passage 12 is connected to a position on the upstream side of the supercharger TC. The purge passage 12 includes an upstream passage 12a located upstream of the purge pump 13 (between the canister 11 and the purge pump 13), and a downstream passage 12b located downstream of the purge pump 13 (between the purge pump 13 and the intake passage IP).

The purge pump 13 is provided in the purge passage 12 and controls the flow of the purge gas flowing through the purge passage 12. That is, the purge pump 13 sends out the purge gas in the canister 11 to the purge passage 12, and supplies the purge gas sent out to the purge passage 12 to the intake passage IP.

The purge control valve 14 is provided at a position downstream of the purge pump 13 (downstream in the flow direction of the purge gas when the purge control is executed), that is, at a position between the purge pump 13 and the intake passage IP in the purge passage 12. The purge control valve 14 is used to open and close the purge passage 12. When the purge control valve 14 is closed (in a state where the valve is closed), the purge gas in the purge passage 12 is stopped by the purge control valve 14 and does not flow into the intake passage IP. On the other hand, when the purge control valve 14 is opened (when the valve is in an open state), the purge gas flows into the intake passage IP.

One end of the atmosphere passage 15 is open to the atmosphere, and the other end of the atmosphere passage 15 is connected to the canister 11, thereby allowing the canister 11 to communicate with the atmosphere. Then, the air taken in from the atmosphere flows into the atmosphere passage 15. The atmosphere passage 15 is provided with a filter 18 and an atmosphere shutoff valve 19. The filter 18 is used to remove foreign matter from the atmosphere (air) flowing into the atmosphere passage 15. The atmosphere shutoff valve 19 opens and closes the atmosphere passage 15.

The vapor passage 16 is connected to the fuel tank FT and the canister 11. Thereby, the evaporated fuel in the fuel tank FT flows into the canister 11 through the vapor passage 16.

The control unit 17 is a part of an ECU (not shown) mounted on the vehicle, and is disposed integrally with other parts of the ECU (for example, a part that controls the engine ENG). The control unit 17 may be disposed separately from the rest of the ECU. The control unit 17 includes a CPU, and memories such as ROM and RAM. The control unit 17 controls the evaporated fuel treatment device 1 and the engine system according to a program stored in advance in a memory. For example, the control unit 17 controls the purge pump 13 and the purge control valve 14. Further, the control unit 17 acquires an output signal (detection result of the air amount) from the air flow meter AFM.

In the present embodiment, the control unit 17 includes an abnormality determination unit 21. The abnormality determination unit 21 determines whether or not the purge passage 12 (specifically, the downstream passage 12b in the purge passage 12) is abnormal (clogged or leaked). The abnormality determination unit 21 may be provided separately from the control unit 17.

In the evaporated fuel treatment device 1 having such a configuration, when the purge condition is satisfied while the engine ENG is operating, the controller 17 controls the purge pump 13 and the purge control valve 14, that is, performs the purge control by opening the purge control valve 14 while driving the purge pump 13. The purge control is control for introducing a purge gas from the canister 11 to the intake passage IP through the purge passage 12.

While the purge control is being executed, air taken into intake passage IP, fuel injected from fuel tank FT via an injector (not shown), and purge gas supplied to intake passage IP by the purge control are supplied to engine ENG. The control unit 17 adjusts the air-fuel ratio (a/F) of the engine ENG to an optimum air-fuel ratio (for example, a stoichiometric air-fuel ratio) by adjusting the injection time of the injector, the valve opening time of the purge control valve 14, and the like.

< control content for determining abnormality of purge passage >

In the present embodiment, the presence or absence of an abnormality in the downstream passage 12b of the purge passage 12 is determined as an On-board diagnostics (OBD) function of the vehicle.

[ first embodiment ]

Specifically, first, as the first embodiment, the abnormality determination unit 21 of the control unit 17 performs control based on the control map shown in fig. 2. That is, when the engine speed and the engine load factor are stable and the abnormality determination is not completed (OBD is not detected) (yes in step S1), the abnormality determination unit 21 performs the abnormality determination control. Further, the abnormality determination unit 21 determines that the engine speed and the engine load factor are stable if the variation thereof falls within a fixed range for a fixed time. As a result, it is possible to determine an abnormality of the purge passage 12 while maintaining the duty ratio of the purge control valve 14 set according to the operating state of the engine ENG, and therefore, it is difficult for fluctuations in the air-fuel ratio (a/F) to occur, and it is therefore possible to determine an abnormality of the purge passage 12 with high accuracy.

When the abnormality determination control is executed, the abnormality determination unit 21 stores the first variation Δ a of the intake air amount from the airflow meter AFM within a predetermined time (for example, 1sec to 2sec) (step S2). The first fluctuation amount Δ a is the amplitude of the air amount, which is the difference between the maximum value (MAX) and the minimum value (MIN) detected by the air flow meter AFM within a predetermined time. In the present embodiment, the first variation amount Δ a is stored when the purge control valve 14 has been opened (when purge control is executed). Further, the first fluctuation amount Δ a may be stored when the purge control valve 14 is closed (purge cutoff time). That is, the first variation Δ a may be obtained when the purge control valve 14 is closed, that is, when the purge is turned off.

Next, the abnormality determination unit 21 sets the drive cycle of the purge control valve 14 to be longer than the initial set value, and sets a guard value (MAX guard) for the drive duty (step S3). The drive cycle of the purge control valve 14 may be set to be about 1.5 to 2.5 times as long as the initial set value. The protection value may be set to about 10% to 40%. In the present embodiment, the drive cycle of the purge control valve 14 is set to 2 times (200ms) the initial set value (100ms), and the duty ratio guard value is set to 40%.

Next, the abnormality determination unit 21 stores the second variation Δ B of the intake air amount from the airflow meter AFM within a predetermined time (for example, 1sec to 2sec) (step S4). The second variation Δ B is the amplitude of the air amount, which is the difference between the maximum value (MAX) and the minimum value (MIN) detected by the air flow meter AFM within a predetermined time period when the drive cycle of the purge control valve 14 is increased.

By thus acquiring the second variation Δ B, the second variation Δ B reliably becomes a larger variation than the first variation Δ a when the purge passage 12 (the downstream passage 12B) is normal. Therefore, erroneous determination of the abnormality of the purge passage 12 (the downstream passage 12b) can be suppressed, and therefore the abnormality of the purge passage 12 (the downstream passage 12b) can be determined with higher accuracy.

The abnormality determination unit 21 determines a determination value X for determining an abnormality in the purge passage 12 (the downstream passage 12 b). The determination value X may be a predetermined value (fixed value), but in the present embodiment, the determination value X is determined according to the rotation speed of the purge pump 13 and the duty ratio of the purge control valve 14 (step S5). Specifically, as shown in fig. 3, the determination value X is determined based on a two-dimensional map determined by the rotation speed of the purge pump 13 and the duty ratio of the purge control valve 14. By determining the determination value X in this manner, the determination value X is set to an optimum value according to the state of purging, and therefore the accuracy of determining an abnormality in the purge passage 12 can be improved. The map data for calculating the determination value X may be obtained in advance by experiments according to the specifications of the engine system (evaporated fuel treatment device 1).

When the difference (Δ B- Δ a) in the amount of fluctuation of the air amount is equal to or greater than the determination value X (yes in step S6), the abnormality determination unit 21 determines that neither clogging nor leakage occurs in the purge passage 12 (the downstream passage 12B), i.e., that the state is normal (step S7). That is, if the drive cycle of the purge control valve 14 is made longer without clogging or leakage in the purge passage 12 (the downstream passage 12b), the purge control valve 14 is opened for a longer time, and therefore the purge gas flowing into the intake passage IP increases, and therefore the amount of air flowing into the intake passage IP decreases by the amount of increase in the purge gas. Therefore, since the second variation Δ B is larger than the first variation Δ a, the abnormality determination unit 21 can determine that neither clogging nor leakage has occurred (normal) in the purge passage 12 (downstream passage 12B) when the variation difference (Δ B- Δ a) is equal to or larger than the determination value X.

When the difference in the amount of fluctuation (Δ B- Δ a) is equal to or greater than the determination value X, the abnormality determination unit 21 determines that neither clogging nor leakage has occurred in the purge passage 12 (downstream passage 12B) (normal).

On the other hand, when the difference (Δ B- Δ a) in the amount of fluctuation of the air amount is smaller than the determination value X (no in step S6), the abnormality determination unit 21 determines that clogging or leakage, i.e., an abnormality, has occurred in the purge passage 12 (the downstream passage 12B) (step S8). That is, when there is an abnormality of clogging or leakage in the purge passage 12 (the downstream passage 12b), the purge gas hardly flows into the intake passage IP, and therefore the amount of air flowing into the intake passage IP hardly changes. Therefore, there is almost no difference between the first variation Δ a and the second variation Δ B, and therefore the abnormality determination unit 21 can determine that clogging or leakage (abnormality) has occurred in the purge passage 12 (the downstream passage 12B) when the variation difference (Δ B- Δ a) is smaller than the determination value X.

When the difference in the amount of fluctuation (Δ B- Δ a) is smaller than the determination value X, the abnormality determination unit 21 determines that clogging or leakage (abnormality) has occurred in the purge passage 12 (downstream passage 12B).

As described above, in the evaporated fuel treatment device 1 of the present embodiment, since the abnormality of the purge passage 12 (the downstream passage 12b) is determined while the duty ratio of the purge control valve 14 set according to the operating state of the engine ENG is maintained, the air-fuel ratio (a/F) fluctuation is less likely to occur. Therefore, it is possible to accurately determine an abnormality in the purge passage 12 (the downstream passage 12 b). Further, since the abnormality of the purge passage 12 (the downstream passage 12b) is determined in accordance with the original purge timing, it is possible to suppress deterioration of the fuel consumption rate and release of the evaporated fuel to the outside air.

Here, a modification will be briefly described. In the above-described embodiment, the abnormality of the purge passage 12 (the downstream passage 12B) is determined based on the difference (Δ B- Δ a) between the first variation Δ a and the second variation Δ B. However, it is also possible to determine an abnormality of the purge passage 12 (the downstream passage 12B) based on the ratio (Δ B/Δ a) of the second variation Δ B to the first variation Δ a. In this case, the determination value X may be determined by using the map shown in fig. 4. That is, in S5 of fig. 2, the abnormality determination unit 21 determines the determination value X based on the map shown in fig. 4. Then, at S6, when the ratio (Δ B/Δ a) of the second fluctuation amount Δ B to the first fluctuation amount Δ a is equal to or greater than the determination value X (S6: "yes"), it is determined that the purge passage 12 (downstream passage 12B) is normal (S7), and when the ratio is smaller than the determination value X (S6: "no"), it is determined that the purge passage 12 (downstream passage 12B) is abnormal (S8). By performing the abnormality determination in this way, as in the above-described embodiment, it is possible to determine the abnormality of the purge passage 12 (the downstream passage 12b) with high accuracy, and it is possible to suppress deterioration of the fuel consumption rate and release of the evaporated fuel into the air.

An example of a control timing chart shown in fig. 5 is implemented by performing control based on the control map shown in fig. 2. As shown in fig. 5, at time T1, the purge control valve 14 is opened to start the purge control. Then, at time T2 to T3, the first variation Δ a is calculated from the maximum value (MAX) and the minimum value (MIN) of the air amount detected by the air flow meter AFM, and the first variation Δ a is stored. In another example, as a method of calculating the first variation Δ a, the first variation Δ a may be calculated from the maximum value (MAX) and the minimum value (MIN) of the air amount detected by the air flow meter AFM at the time of purge cutoff (time t01 to time t02), and the first variation Δ a may be stored.

Next, at time T3, the drive cycle of the purge control valve 14 is set to be longer (200ms) than the initial set value (100ms), and the duty ratio is set to a guard value (40%). Then, at time T3 to T4, the second variation Δ B is calculated from the maximum value (MAX) and the minimum value (MIN) of the air amount detected by the air flow meter AFM, and the second variation Δ B is stored.

Then, at time T4, when the difference (Δ B- Δ a) or the ratio (Δ B/Δ a) between the second variation Δ B and the first variation Δ a is equal to or greater than the determination value X (when the intake air amount greatly changes), it is determined that neither clogging nor leakage has occurred in the purge passage 12 (downstream passage 12B), and it is normal (solid line in fig. 5). On the other hand, if the difference (Δ B- Δ a) between the second variation Δ B and the first variation Δ a is smaller than the determination value X (if the intake air amount is hardly changed), it is determined that clogging or leakage occurs in the purge passage 12 (the downstream passage 12B) and it is abnormal (broken line in fig. 5).

[ second embodiment ]

Next, as a second embodiment, the abnormality determination section 21 performs control based on the control map shown in fig. 6. That is, when the engine speed and the engine load factor are stable and the abnormality determination is not completed (OBD is not detected) (yes in step S11), the abnormality determination unit 21 performs the abnormality determination control.

When the abnormality determination control is executed, the abnormality determination unit 21 sets the drive cycle of the purge control valve 14 to be longer than the initial setting value and sets a guard value (MAX guard) for the drive duty (step S12). The drive cycle of the purge control valve 14 may be set to be about 1.5 to 2.5 times as long as the initial set value. The protection value may be set to about 10% to 50%. In the present embodiment, the drive cycle of the purge control valve 14 is set to 2 to 2.5 times (200 to 250ms) the initial set value (100ms), and the duty ratio guard value is set to 50%. It is not necessarily essential to extend the drive cycle of the purge control valve 14 (i.e., set longer than the initial set value), but it is preferable to extend the drive cycle so as to improve the accuracy of determining an abnormality in the purge passage 12 (downstream passage 12 b).

Next, the abnormality determination unit 21 obtains an average value (hereinafter referred to as "calculated value α") of the value after the annealing process or the previous data with respect to the intake air amount detected by the air flow meter AFM (hereinafter referred to as "air flow meter air amount") (step S13).

The annealing process is a process of calculating the air flow meter air amount sm [ N ] after the current process from the following equation using the current air flow meter air amount NI, the air flow meter air amount sm [ N-1] after the previous process, and the annealing number TN. N is an integer of 2 or more.

[ number 1]

sm[N]←sm[N-1]+(Nl-sm[N-1])/TN

Next, the abnormality determination unit 21 calculates the period (T α 1, T α 2, …, T α n) in which the air flow rate measurement air amount passes through the calculated value α (step S14 (I)). Fig. 7, which will be described later, shows an example of the calculated value α and the period (T α 1, T α 2, …, T α n). N is an integer of 3 or more, and is "4" in the example shown in fig. 7. The periods (T α 1, T α 2, …, T α n) are an example of the "variation period" in the present disclosure.

Next, when the drive cycle of the purge control valve 14 and the average value of the cycles (T α 1, T α 2, …, T α n) are approximate (i.e., coincide or substantially coincide) after the average value of the cycles (T α 1, T α 2, …, T α n) is calculated by the abnormality determination unit 21 (yes in step S15), the abnormality determination unit 21 determines that the purge passage 12 (the downstream passage 12b) is neither clogged nor leaked, i.e., is normal (step S16). That is, when there is neither clogging nor leakage in the purge passage 12 (the downstream passage 12b), the purge gas does not flow into the intake passage IP when the purge control valve 14 is in the closed state (i.e., in the closed state), while the purge gas flows into the intake passage IP when the purge control valve 14 is in the open state (i.e., in the open state), and therefore the air flow meter air amount fluctuates in conjunction with the driving of the opening and closing of the purge control valve 14. Therefore, when the purge passage 12 (the downstream passage 12b) is neither clogged nor leaked, it is considered that the drive cycle of the purge control valve 14 is approximate to the average value of the cycles (T α 1, T α 2, …, T α n). Therefore, when the drive cycle of the purge control valve 14 is similar to the average value of the cycles (T α 1, T α 2, …, T α n), the abnormality determination unit 21 determines that neither clogging nor leakage has occurred in the purge passage 12 (downstream passage 12b) (normal).

Further, as a case where the drive cycle of the purge control valve 14 is approximate to the average value of the cycles (T α 1, T α 2, …, T α n), for example, a case where the average value of the cycles (T α 1, T α 2, …, T α n) is in the range of 0.8 to 1.2 times the drive cycle of the purge control valve 14 is considered. Here, as an example, if the average value of the periods (T α 1, T α 2, …, T α n) is in the range of 180ms to 220ms when the drive period of the purge control valve 14 is 200ms, it corresponds to a case where the drive period of the purge control valve 14 is similar to the average value of the periods (T α 1, T α 2, …, T α n).

On the other hand, when the drive cycle of the purge control valve 14 is not similar to the average value of the cycles (T α 1, T α 2, …, T α n) (no in step S15), the abnormality determination unit 21 determines that clogging or leakage, that is, an abnormality has occurred in the purge passage 12 (the downstream passage 12b) (step S17). That is, when there is a blockage or leakage abnormality in the purge passage 12 (the downstream passage 12b), the purge gas hardly flows into the intake passage IP even if the purge control valve 14 is opened, and therefore the amount of air flowing into the intake passage IP hardly changes. Therefore, a difference is generated between the drive period and the period (T α 1, T α 2, …, T α n) of the purge control valve 14. Therefore, when the drive cycle of the purge control valve 14 is not similar to the average value of the cycles (T α 1, T α 2, …, T α n), the abnormality determination unit 21 determines that clogging or leakage (abnormality) has occurred in the purge passage 12 (downstream passage 12 b).

As described above, in the evaporated fuel processing device 1 of the present embodiment, the abnormality determination unit 21 determines whether or not there is an abnormality in the purge passage 12 based on the difference between the variation cycle of the detection value detected by the air flow meter AFM and the drive cycle of the purge control valve 14. At this time, since the abnormality of the purge passage 12 (the downstream passage 12b) is determined while the duty ratio of the purge control valve 14 set according to the operating state of the engine ENG is maintained, the air-fuel ratio (a/F) fluctuation is less likely to occur. Therefore, it is possible to accurately determine an abnormality in the purge passage 12 (the downstream passage 12 b). Further, since the abnormality of the purge passage 12 (the downstream passage 12b) is determined in accordance with the original purge timing, it is possible to suppress deterioration of the fuel consumption rate and release of the evaporated fuel to the outside air.

In the evaporated fuel treatment device 1 of the present embodiment, the average value of the variation cycle of the air flow meter air amount within a predetermined time is used as the variation cycle of the air flow meter air amount. That is, the abnormality determination unit 21 determines whether or not there is an abnormality in the purge passage 12 (the downstream passage 12b) based on the difference between the drive cycle of the purge control valve 14 and the average value of the cycles (T α 1, T α 2, …, T α n). Therefore, it is possible to determine an abnormality of the purge passage 12 (the downstream passage 12b) while being less susceptible to the influence of the frequency change due to the external disturbance relating to the air flow meter amount.

An example of the control timing chart shown in fig. 7 is implemented by performing control based on the control map shown in fig. 6. As shown in fig. 7, at time T11, the purge control valve 14 is opened to start the purge control. Next, at time T12, the drive cycle of the purge control valve 14 is set to be longer (200ms) than the initial set value (100ms), and the duty ratio is set to a guard value (40%).

Next, at time T12 to T13, the purge control valve 14 is driven to open and close. At this time, if the drive cycle of the purge control valve 14 is similar to the average value of the cycles (T α 1, T α 2, …, T α n), it is determined that neither clogging nor leakage has occurred in the purge passage 12 (downstream passage 12b) (normal). On the other hand, if the drive cycle of the purge control valve 14 is not similar to the average value of the cycles (T α 1, T α 2, …, T α n), it is determined that clogging or leakage (abnormality) has occurred in the purge passage 12 (downstream passage 12 b).

Next, a modified example will be described. First, in the first modification, the abnormality determination unit 21 calculates the number of times the airflow meter air amount passes by the calculated value α (hereinafter referred to as "the number of times X α" passed ") (step S14 (II)). Here, the number of elapsed times X α is the number of times the calculated value α has elapsed while the airflow meter air amount is changing from the maximum value (MAX) to the minimum value (MIN) or while the airflow meter air amount is changing from the minimum value (MIN) to the maximum value (MAX) within a predetermined time (i.e., while the drive cycle of the purge control valve 14 is set to be longer than the initial set value). In the example shown in fig. 7, the number of passes X α is, for example, the number of black dots (i.e., "4") in the waveform of the air flow meter air amount.

Next, when the number of times of opening and closing of the purge control valve 14 (excluding the first time) is similar to the number of times of passage X α (yes in (II) of step S15), the abnormality determination unit 21 determines that it is normal (step S16). That is, when the purge passage 12 (the downstream passage 12b) is not clogged or does not leak, the purge gas does not flow into the intake passage IP when the purge control valve 14 is in the closed state, and the purge gas flows into the intake passage IP when the purge control valve 14 is in the open state, and therefore the air flow meter air amount fluctuates in conjunction with the opening/closing drive of the purge control valve 14. Therefore, when the purge passage 12 (the downstream passage 12b) is not clogged or does not leak, it is considered that the number of times of opening and closing of the purge control valve 14 is approximate to the elapsed number of times X α. Therefore, when the number of times of opening and closing of the purge control valve 14 is similar to the elapsed number of times X α, the abnormality determination unit 21 determines that neither clogging nor leakage has occurred in the purge passage 12 (the downstream passage 12b) (normal).

The number of times the purge control valve 14 is opened/closed is the number of times the purge control valve 14 is switched from the state in which the purge control valve 14 is opened (or closed) to the state in which the purge control valve 14 is closed (or opened) within a predetermined time (that is, within a time period in which the drive cycle of the purge control valve 14 is set longer than the initial set value). In the example shown in fig. 7 described above, the number of times the purge control valve 14 is opened and closed is "4".

In addition, as a case where the number of times of opening and closing of the purge control valve 14 is approximate to the number of times of passage X α, for example, a case where the number of times of passage X α is in a range of 0.8 to 1.2 times the number of times of opening and closing of the purge control valve 14 is considered.

On the other hand, when the number of times the purge control valve 14 is opened and closed is not similar to the elapsed number of times X α (no in step S15), the abnormality determination unit 21 determines that clogging or leakage, that is, an abnormality, has occurred in the purge passage 12 (the downstream passage 12b) (step S17). That is, when there is a blockage or leakage abnormality in the purge passage 12 (the downstream passage 12b), the purge gas hardly flows into the intake passage IP even if the purge control valve 14 is opened, and therefore the amount of air flowing into the intake passage IP hardly changes. Therefore, a difference is generated between the number of times the purge control valve 14 is opened and closed and the number of times X α elapsed. Therefore, when the number of times of opening and closing of the purge control valve 14 is not close to the elapsed number of times X α, the abnormality determination unit 21 determines that clogging or leakage (abnormality) has occurred in the purge passage 12 (the downstream passage 12 b).

In the second modification, as shown in fig. 8, the point different from fig. 6 is that the abnormality determination unit 21 calculates the period (T β 1, T β 2, …, T β n) of the peak value β of the air flow rate of the air flow meter (step S23 (I)). Fig. 9 shows an example of the periods (T β 1, T β 2, …, T β n). The period (T β 1, T β 2, …, T β n) is an example of the "variation period" in the present disclosure.

Next, when the drive cycle of the purge control valve 14 is similar to the average value of the cycles (T β 1, T β 2, …, T β n) after the average value of the cycles (T β 1, T β 2, …, T β n) is calculated by the abnormality determination unit 21 (yes in step S24), the abnormality determination unit 21 determines that the purge passage 12 (the downstream passage 12b) is not clogged or is not leaked, that is, is normal (step S25). That is, when the purge passage 12 (the downstream passage 12b) is not clogged or does not leak, the purge gas does not flow into the intake passage IP when the purge control valve 14 is in the closed state, and the purge gas flows into the intake passage IP when the purge control valve 14 is in the open state, and therefore the air flow meter air amount fluctuates in conjunction with the opening/closing drive of the purge control valve 14. Therefore, when the purge passage 12 (the downstream passage 12b) is neither clogged nor leaked, it is considered that the drive cycle of the purge control valve 14 is approximate to the average value of the cycles (T β 1, T β 2, …, T β n). Therefore, when the drive cycle of the purge control valve 14 is similar to the average value of the cycles (T β 1, T β 2, …, T β n), the abnormality determination unit 21 determines that neither clogging nor leakage occurs (normality) in the purge passage 12 (downstream passage 12 b).

In addition, as a case where the drive cycle of the purge control valve 14 is similar to the cycle (T β 1, T β 2, …, T β n), for example, a case where the cycle (T β 1, T β 2, …, T β n) is in the range of 0.8 to 1.2 times the drive cycle of the purge control valve 14 is considered.

On the other hand, when the drive cycle of the purge control valve 14 is not similar to the cycle (T β 1, T β 2, …, T β n) (no in step S24), the abnormality determination unit 21 determines that clogging or leakage, that is, an abnormality has occurred in the purge passage 12 (downstream passage 12b) (step S26). That is, when there is an abnormality of clogging or leakage in the purge passage 12 (the downstream passage 12b), the purge gas hardly flows into the intake passage IP, and therefore the amount of air flowing into the intake passage IP hardly changes. Therefore, a difference occurs between the drive period and the period (T β 1, T β 2, …, T β n) of the purge control valve 14. Therefore, when the drive cycle of the purge control valve 14 is not similar to the cycle (T β 1, T β 2, …, T β n), the abnormality determination unit 21 determines that clogging or leakage (abnormality) has occurred in the purge passage 12 (downstream passage 12 b).

In the third modification, as shown in fig. 8, the difference from fig. 6 is that the abnormality determination unit 21 calculates the number of times of the peak value β of the air flow meter air amount (hereinafter referred to as "peak number X β") (step S23 (II)).

Next, when the number of times the purge control valve 14 is opened and closed is similar to the peak number X β (yes in step S24), the abnormality determination unit 21 determines that there is neither clogging nor leakage in the purge passage 12 (the downstream passage 12b), that is, it is normal (step S25). That is, when the purge passage 12 (the downstream passage 12b) is not clogged or does not leak, the purge gas does not flow into the intake passage IP when the purge control valve 14 is in the closed state, and the purge gas flows into the intake passage IP when the purge control valve 14 is in the open state, and therefore the air flow meter air amount fluctuates in conjunction with the opening/closing drive of the purge control valve 14. Therefore, when the purge passage 12 (the downstream passage 12b) is neither clogged nor leaked, it is considered that the number of times the purge control valve 14 is opened and closed is approximate to the peak number X β. Therefore, when the number of times the purge control valve 14 is opened and closed is close to the peak number X β, the abnormality determination unit 21 determines that neither clogging nor leakage occurs in the purge passage 12 (the downstream passage 12b) (normal).

In addition, as a case where the number of times the purge control valve 14 is opened and closed is similar to the peak number X β, for example, a case where the peak number X β is in a range of 0.8 to 1.2 times the number of times the purge control valve 14 is opened and closed is considered.

On the other hand, when the number of times the purge control valve 14 is opened and closed is not similar to the peak number X β (no in step S24), the abnormality determination unit 21 determines that clogging or leakage, that is, an abnormality, has occurred in the purge passage 12 (the downstream passage 12b) (step S26). That is, when there is an abnormality of clogging or leakage in the purge passage 12 (the downstream passage 12b), the purge gas hardly flows into the intake passage IP, and therefore the amount of air flowing into the intake passage IP hardly changes. Therefore, a difference is generated between the number of times the purge control valve 14 is opened and closed and the peak number X β. Therefore, when the number of times the purge control valve 14 is opened and closed is not close to the peak number X β, the abnormality determination unit 21 determines that clogging or leakage (abnormality) has occurred in the purge passage 12 (the downstream passage 12 b).

The above-described embodiments are merely illustrative, and the present disclosure is not limited to these embodiments, and it is needless to say that various improvements and modifications can be made without departing from the scope of the present disclosure. For example, in the above-described embodiment, the evaporated fuel treatment apparatus of the present disclosure is applied to an engine system with a supercharger TC, but it is needless to say that the evaporated fuel treatment apparatus of the present disclosure may be applied to an engine system with natural intake air.

Description of the reference numerals

1: an evaporated fuel treatment device; 11: an adsorption tank; 12: a purge passage; 12 b: a downstream side passage; 13: a purge pump; 14: a purge control valve; 16: a vapor passage; 17: a control unit; 21: an abnormality determination unit; AFM: an air flow meter; ENG: an engine; FT: a fuel tank; α: calculating a value; (ta 1, ta 2, …, ta n): a period; x α: the number of passes; beta: a peak value; (T β 1, T β 2, …, T β n): a period; x beta is as follows: number of peaks.