JP2015190348A - Fuel evaporation gas discharge restraining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel evaporation gas discharge restraining device enabled not only to determine the presence or absence of the leakage of a fuel evaporation gas and to specify a leakage portion but also to detect a sensor abnormality.SOLUTION: A first determination is made to determine the presence or absence of the leakage of a fuel evaporation gas, while a first switch being closed, second and third switches being opened, and a fourth switch being closed, on the basis of the detection result of a canister pressure detecting part at the time when a pressure is generated in a canister by a pressure generating part. In the case where the leakage of the fuel evaporation gas is determined by the first determination, a second determination for determining the presence or absence of the leakage of the fuel evaporation gas is made, while the third switch has been switched from the opened state to the closed state, on the basis of the detection result of the canister pressure detecting part at the time when the pressure is established in the canister.

Description

  The present invention relates to a fuel evaporative gas emission suppressing device that introduces fuel evaporative gas in a fuel tank into an intake system of an engine and suppresses the emission to the atmosphere, and in particular, technology for detecting leakage of fuel evaporative gas. About.

  Since the fuel evaporative gas generated in the fuel tank causes air pollution, the fuel evaporation gas processing device for suppressing the emission of the fuel evaporative gas into the atmosphere is generally used for a vehicle equipped with an engine. Is installed. The fuel evaporative gas processing apparatus, for example, connects a fuel tank and an intake system of an engine with a purge line equipped with a canister, and once adsorbs the fuel evaporative gas generated in the fuel tank to activated carbon in the canister, The fuel adsorbed by activated carbon according to the intake negative pressure is introduced into the intake system of the engine and burned with fresh air.

  In recent years, for example, plug-in hybrid vehicles (PHEV), hybrid vehicles (HEV), and the like, vehicles equipped with a motor for traveling with an engine have been put into practical use. In a vehicle equipped with such a traveling motor, a period during which the engine is stopped, that is, a period during which fuel cannot be introduced from the canister into the engine intake system may continue for a relatively long time. For this reason, a so-called sealed fuel evaporative emission control device has been developed in which a sealing valve is provided between the fuel tank and the canister and the sealing valve is closed during a period when the engine is stopped. Furthermore, in the closed type fuel evaporative emission control device, for example, an on-off valve is provided near the inlet of the canister, and when this on-off valve is closed, the fuel evaporative gas is not introduced into the canister and enters the engine intake system Some are introduced directly.

  By the way, if the fuel evaporative gas leaks due to some trouble in such a fuel evaporative gas emission control device, it directly leads to air pollution. For this reason, in the United States and the like, it is legally required to detect leakage of fuel evaporative gas. In particular, in US laws and regulations, such a self-diagnosis diagnosis (OBD: On Board Diagnosis) that detects a leak of fuel evaporative gas is performed, and when a leak is detected, for example, by turning on a warning lamp, etc. It is obliged to inform the driver. Of course, it is also required to detect leaks in the sealed fuel evaporative emission control device.

  In response to such a demand, for example, there is one that detects the presence or absence of leakage of fuel evaporative gas based on the difference between the inside of the fuel tank and the atmospheric pressure. Specifically, a forced open / close valve is provided in the vapor path connecting the canister and the fuel tank. The forced open / close valve is closed except during refueling, and the forced open / close valve is closed when the engine is cold started or started. Measure the internal pressure of the fuel tank in the sealed state. The fuel tank leaks only on condition that the absolute value of the difference between the tank internal pressure and the atmospheric pressure is not less than a predetermined judgment value indicating that the confidentiality of the fuel tank is sufficiently maintained. In some cases, it is determined that there is no abnormality (see Patent Document 1).

Japanese Patent No. 3620402

  Even with such an apparatus described in Patent Document 1, if the pressure sensor that detects the internal pressure of the fuel tank functions normally, it is possible to determine whether or not there is a leak of fuel evaporative gas.

  However, in the above apparatus, the pressure in the tank is measured by the pressure sensor in a state where there is almost no pressure change in the fuel tank. For this reason, even when a sensor abnormality occurs, it is difficult to detect the abnormality. For example, the tank internal pressure may be erroneously determined to be in an appropriate range due to sensor abnormality.

  Further, in the above apparatus, it is possible to determine whether or not there is a leak of fuel evaporative gas, but it is difficult to specify the leak location.

  The present invention has been made in view of such circumstances, and it is possible to determine whether or not there is a leak of fuel evaporative gas, to specify a leak location, and to detect a sensor abnormality, and to detect fuel evaporative gas An object is to provide a suppression device.

  According to a first aspect of the present invention, there is provided a first communication path that communicates an intake passage of a vehicle engine and a canister, a second communication path that communicates the canister and a fuel tank, and the canister and outside air. A third communication path communicating with the first communication path; a first opening / closing portion provided in the first communication path for opening and closing the first communication path; and a second communication path provided in the second communication path. A third opening / closing portion that is provided closer to the canister than a connection portion between the second opening / closing portion that opens and closes the passage and the first communication passage of the second communication passage and opens and closes the first communication passage. A fourth opening / closing part provided in the third communication path for opening / closing the third communication path, and a pressure generating part for generating pressure in the canister via the third communication path A canister pressure detecting unit for detecting the pressure in the canister, and the first opening / closing unit are closed. And detecting the canister pressure detection unit when pressure is generated in the canister by the pressure generation unit with the second and third opening / closing units open and the fourth opening / closing unit closed. Based on the result, a first determination is made to determine whether or not there is a fuel evaporative gas leak. If the first determination determines that there is a fuel evaporative gas leak, the third open / close section is opened. A determination unit that performs a second determination that determines whether or not there is a leak of fuel evaporative gas based on a detection result of the canister pressure detection unit when pressure is generated in the canister in a state of switching to the closed state; A fuel evaporative emission control device.

  According to a second aspect of the present invention, in the fuel evaporative emission control device according to the first aspect, when the determination unit executes the first determination, a detection result of the canister pressure detection unit is set in advance. The fuel evaporative emission control apparatus determines that there is a leak when the first pressure is not reached.

  According to a third aspect of the present invention, in the fuel evaporative emission control device according to the first or second aspect, when the determination unit performs the second determination, the detection result of the canister pressure detection unit is previously stored. When the set second negative pressure is not reached, it is determined that a leak has occurred on the canister side with respect to the third opening / closing portion, and the detection result of the canister pressure detection portion indicates the second pressure. If it exceeds, the fuel evaporative emission control device determines that a leak has occurred on the fuel tank side of the third opening / closing portion.

  According to a fourth aspect of the present invention, in the fuel evaporative emission control device according to any one of the first to third aspects, the fuel evaporative emission control device further includes a tank pressure detection unit that detects a pressure in the fuel tank, and the determination unit includes Prior to the first determination, a pre-determination for determining whether or not there is a leak of fuel evaporative gas based on the detection results of the canister pressure detection unit and the tank pressure detection unit is performed. In the fuel evaporative emission control device, the first determination is executed when it is not determined that there is no leak.

  According to a fifth aspect of the present invention, in the fuel evaporative emission control device according to the fourth aspect, the determination unit opens the second opening / closing unit when executing the pre-determination, and the first and third When the pressure of the fuel tank when the opening / closing part of the fuel tank is reduced to a first threshold value set in advance within a predetermined time, or when the second opening / closing part is opened, the first and third opening / closing parts are opened. Even when the pressure of the fuel tank when the part is closed does not drop to the first threshold value set in advance within a predetermined time, the second opening / closing part is opened and the first and fourth opening / closing parts are opened. When the third open / close part is switched from closed to open while the pressure generating part is stopped, the pressure of the canister rises or falls to a preset second threshold value within a predetermined time. Without judging that there is no leak of fuel evaporative gas Serial in evaporative emission suppressing apparatus characterized by performing a first determination.

  According to a sixth aspect of the present invention, in the fuel evaporative emission control device according to the fourth or fifth aspect, the first determination is not executed when it is determined by the pre-determination that there is no leakage of the fuel evaporative gas. In the fuel evaporative emission control device, the second determination is performed.

  In the present invention, it is possible to accurately determine whether or not the fuel evaporative gas leaks, and to specify the leak location. It is also possible to detect an abnormality such as a pressure sensor used for determining a leak.

1 is a schematic configuration diagram showing a fuel evaporative emission control device according to an embodiment of the present invention. It is a figure which shows schematic structure of an evaporative leak check module. It is a timing chart which shows the operating state etc. of the valve in pre-determination. It is a timing chart which shows the operating state etc. of the valve in the 1st and 2nd judgment. It is a timing chart which shows the operating state etc. of the valve in the 1st and 2nd judgment. It is a timing chart which shows the operating state etc. of the valve in the 1st and 2nd judgment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a fuel evaporative emission control device 10 according to the present embodiment is mounted on a vehicle such as an automobile, and a fuel evaporative gas generated in a fuel tank 101 in which fuel supplied to an engine 100 is stored ( This is a device for suppressing vapor) from being discharged into the atmosphere.

  The fuel evaporative emission control device 10 includes a canister 12 in which activated carbon is enclosed. The canister 12 communicates with the intake passage 102 of the engine via a purge pipe (first communication path) 14 and also communicates with the fuel tank 101 via a vapor pipe (second communication path) 16. . The vapor pipe 16 is provided with a tank pressure sensor (tank pressure detector) 17 for detecting the pressure in the fuel tank 101. Hereinafter, the pressure detected by the tank pressure sensor 17 is also simply referred to as “tank pressure”.

  Here, the purge pipe 14 is provided with a purge valve (first opening / closing part) 18 for opening and closing the purge pipe 14. By appropriately switching the open / close state of the purge valve 18, the supply state of the fuel adsorbed by the canister 12 to the intake passage 102 is controlled. The purge valve 18 is driven by, for example, an electromagnetic solenoid. The purge valve 18 is a so-called normally closed electromagnetic valve, which is closed when the electromagnetic solenoid is not energized, and is opened when the electromagnetic solenoid is energized.

  The end of the purge pipe 14 opposite to the intake passage 102 is connected to the vicinity of the canister 12 of the vapor pipe 16. A sealing valve (second opening / closing portion) 20 for opening and closing the vapor piping 16 is provided closer to the fuel tank 101 than the connection portion 16a of the vapor piping 16 to the purge piping 14. Further, an opening / closing valve (third opening / closing portion) 22 is provided on the canister 12 side of the connection portion 16a of the vapor piping 16 with the purge piping 14. The sealed valve 20 is a so-called normally-closed solenoid valve, like the purge valve 18, and the open / close valve 22 is a so-called normally-open solenoid valve, unlike the purge valve 18 and the like.

  In addition, a vent pipe (third communication path) 24 is connected to the canister 12, and the canister 12 communicates with the outside through the vent pipe 24. An evaporative leak check module (ELCM) 26 for detecting leaks from the fuel tank 101 and the canister 12 and the purge pipe 14 and the vapor pipe 16 connected to the fuel tank 101 and the canister 12 is provided in the middle of the vent pipe 24.

  As shown in FIG. 2, the ELCM 26 includes a first flow path 28 that communicates with the canister 12, a second flow path 30 that is opened to the atmosphere through the vent pipe 24, a first flow path 28, and a second flow path. A third flow path 32 connected in the middle of the flow path 30. A switching valve (fourth opening / closing part) 34 is provided between the first flow path 28, the second flow path 30 and the third flow path 32.

  The connection between the first flow path 28 and the second flow path 30 or the third flow path 32 is configured to be switchable by the switching valve 34. For example, the switching valve 34 communicates the first flow path 28 and the second flow path 30 in a state where the electromagnetic solenoid is not energized, and when the electromagnetic solenoid is energized, the first flow path 28 and the third flow path 30 are communicated. The flow path 32 is communicated.

  The third flow path 32 is provided with a negative pressure pump 36 that generates a negative pressure in the canister 12. The first flow path 28 and the third flow path 32 include a fourth flow path 38 provided across the switching valve 34. For example, a reference orifice 40 having a diameter of 0.5 mm is provided in the fourth flow path 38, and a canister for detecting the pressure in the canister 12 on the second flow path 30 side of the reference orifice 40. A pressure sensor (canister pressure detector) 42 is provided. Hereinafter, the pressure detected by the canister pressure sensor 42 is also simply referred to as “canister pressure”.

  The negative pressure pump (pressure generating unit) 36 constituting the ELCM 26 and the purge valve 18, the sealing valve 20, and the opening / closing valve 22 described above are controlled based on a control signal from the ECU 50. The ECU 50 also includes a determination unit 51. The determination unit 51 performs a first determination and a second determination for determining the presence or absence of the fuel evaporative gas leak and the leak location. Specifically, the possibility of occurrence of a leak and a leak location are determined based on a change in tank pressure when the sealing valve 20 is switched from closed to open. Moreover, in this embodiment, after performing these 1st and 2nd determination, a 3rd and 4th determination is performed further. In these third and fourth determinations, negative pressure is generated in the canister 12 by the negative pressure pump 36 in a predetermined state, and the pressure at that time is detected by the canister pressure sensor 42 and the tank pressure sensor 17, and the determination unit 51 Determines the presence or absence of a leak or a leak location based on the detection result. If the determination unit 51 determines that there is a leak, a warning is given to the driver, for example, by turning on a warning lamp for leak display provided in the driver's seat.

  Hereinafter, with reference to FIG. 3 and FIG. 4, the presence / absence of a leak and a method for detecting a leak location by the determination unit 51 will be described. FIG. 3 is a timing chart showing the operation state of each valve, the canister pressure, and the tank pressure in time series in the pre-determination, and FIG. 4 shows the operation state of each valve in the first determination and the second determination. It is a timing chart which shows canister pressure and tank pressure in time series.

  The determination unit 51 performs the pre-determination without operating the negative pressure pump 36, for example, when the key is off. First, the first pre-determination is executed, and based on the tank pressure, whether fuel evaporative gas leaks on the fuel tank 101 side of the opening / closing valve 22, that is, in the path excluding the canister 12 (possibility of leak occurrence) Determine.

  The first pre-determination is executed in a period T1-T2 shown in FIG. Before the start of the first determination, the purge valve 18 and the sealing valve 20 are controlled to be closed, and the switching valve 34 and the opening / closing valve 22 are controlled to be opened. In this state, the fuel tank 101 is closed by the sealing valve 20. At this time, the tank pressure can be any of a positive pressure, a negative pressure, and the vicinity of atmospheric pressure when there is no leak in the fuel tank 101. On the other hand, when a leak occurs in the fuel tank 101, the tank pressure does not become a positive pressure or a negative pressure and is close to the atmospheric pressure.

  Thereafter, at time T1, the on-off valve 22 is switched to the closed state, and the sealed valve 20 is switched to the opened state. As a result, the fuel tank 101 and the purge pipe 14 and the vapor pipe 16 communicate with each other. The determination unit 51 determines whether or not there is a leak in the fuel tank 101, the purge pipe 14, and the vapor pipe 16 based on a change in tank pressure at that time, that is, a change in pressure value detected by the tank pressure sensor 17. That is, when the absolute value of the change amount of the tank pressure exceeds a predetermined value, it is determined that there is a possibility of leakage. For example, when the tank pressure Pt at the time T1 is a positive pressure, it is determined whether or not the tank pressure Pt has decreased below a preset first threshold value P1.

  In the example shown in FIG. 3 (a), since the tank pressure Pt has dropped below the first threshold value P1 during the period T1-T2, somewhere in the fuel tank 101, the purge pipe 14 and the vapor pipe 16. It is determined that there is a possibility that a leak has occurred. As described above, when the tank pressure Pt is maintained at a positive pressure, when the first determination is started and the sealing valve 20 is switched to the valve open state, the tank pressure is maintained even in a normal state without leakage. Slightly lower. However, since the volume of the fuel tank 101 is overwhelmingly larger than the volumes of the purge pipe 14 and the vapor pipe 16, the tank pressure drop during normal operation is extremely small as shown in FIGS. . Therefore, if the tank pressure Pt drops below the first threshold value P1 during the first determination, there is a possibility that a leak has occurred somewhere in the fuel tank 101, the purge pipe 14, and the vapor pipe 16. Can be determined.

  In the example shown in FIG. 3A, since the tank pressure Pt is held at a positive pressure at time T1 when the sealing valve 20 is closed, it can be determined that there is no leak in the fuel tank 101. As a result, it can be determined that the leak has occurred in either the purge pipe 14 or the vapor pipe 16.

  On the other hand, as shown in FIGS. 3B and 3C, when the tank pressure Pt does not decrease beyond the first threshold value P1 between T1 and T2, the fuel tank 101, the purge pipe 14, and the vapor pipe. 16, it is not possible to determine that there is a possibility that a leak has occurred. Therefore, the second pre-determination is further executed to determine whether there is a leak in the fuel tank 101, the purge pipe 14, and the vapor pipe 16.

  Specifically, as shown in FIGS. 3B and 3C, the switching valve 34 is closed at time T3, that is, the first flow path 28 and the third flow path 32 constituting the ELCM 26 are connected. After that, the open / close valve 22 is switched to the open state at time T4. As a result, the canister 12 is in communication with the fuel tank 101, the purge pipe 14, and the vapor pipe 16 described above. Then, the determination unit 51 determines whether or not there is a leak in the fuel tank 101, the purge pipe 14, and the vapor pipe 16 based on the change in the canister pressure at this time. That is, in the second pre-determination, it is determined that there is a leak when the canister pressure Pc rises or falls in a period T4-T5 exceeding a preset threshold value. That is, it is determined that there is a leak when the absolute value of the change amount of the canister pressure exceeds a threshold value.

  For example, when the tank pressure Pt at time T1 is positive as described above, the canister pressure Pc increases between T4 and T5 as shown in FIGS. For this reason, in the second pre-determination, it is determined whether or not the change amount (rise amount) of the canister pressure Pc between T4 and T5 exceeds the second threshold value P2.

  The switching valve 34 is open until time T3, that is, the first flow path 28 and the second flow path 30 communicate with each other and the canister 12 is opened to the atmosphere. Therefore, when the tank pressure Pc is maintained at a positive pressure at time T1 as described above, when the on-off valve 22 is switched to the open state at time T4, the canister pressure Pc is significantly lower than the tank pressure Pt. The pressure is close to atmospheric pressure. Therefore, when the on-off valve 22 is switched to the open state at time T4, the canister pressure Pc greatly increases under the influence of the tank pressure Pt in the normal state. Therefore, for example, when the canister pressure Pc increases beyond the second threshold value P2 in the period T4-T5 (FIG. 3B), there is no leakage in the fuel tank 101, the purge pipe 14, and the vapor pipe 16. Can be determined. When the canister pressure Pc rises above the second threshold value P2 between T4 and T5 as described above, it can be determined that there is no abnormality (for example, sticking) of the opening / closing valve 22 and the sealing valve 20.

  On the other hand, when the canister pressure Pc does not reach the second threshold value P2 between T4 and T5 when the on-off valve 22 is switched to the open state (FIG. 3 (c)), the fuel tank 101, the purge pipe 14 and It is difficult to determine whether there is a leak in the vapor pipe 16. That is, the possibility of leakage in the fuel tank 101, the purge pipe 14, and the vapor pipe 16 cannot be completely denied. For this reason, the determination unit 51 further performs the first determination and the second determination as described below.

  In the first determination, the presence or absence of a leak is determined according to the canister pressure Pc. As shown in FIGS. 4 and 5, first, the purge valve 18 is closed, the sealing valve 20, the switching valve 34, and the open / close valve 22 are opened, and the negative pressure pump 36 is operated at time T6. Thus, negative pressure is generated in the canister 12 (actually, negative pressure is generated in the third flow path 32 between the negative pressure pump 36 and the reference orifice 40), and the canister pressure at that time is detected. The reference pressure (first negative pressure) is used. Thereafter, at time T7, the switching valve 34 is switched to the closed state to connect the first flow path 28 and the third flow path 32, and a change in canister pressure is detected between T7 and T8. Thereafter, at time T8, the switching valve 34 is switched to the open state to connect the first flow path 28 and the second flow path 30. Then, the canister pressure is detected between T8 and T9, and is set as the reference pressure (first negative pressure) again.

  As shown in FIG. 4, if the canister pressure Pc is smaller than the detected reference pressure (first negative pressure), that is, if the negative pressure is larger than the reference pressure (first negative pressure), the fuel It is determined that there is no leak in either the tank 101 or the canister 12. As shown in FIGS. 5A and 5B, if the pressure detected between T7 and T8 is larger than the reference pressure (first negative pressure) detected again between T9 and T10, that is, the reference pressure ( If the negative pressure is smaller than the first negative pressure), it is determined that there is a hole larger than the inner diameter of the reference orifice 40. That is, it is determined that a leak has occurred somewhere in the fuel tank 101, the canister 12, or each communication path.

  In this case, the determination unit 51 further performs a second determination to determine whether there is a leak. Specifically, as shown in FIGS. 5A and 5B, after the first determination, the switching valve 34 is switched to the closed state at time T9, and the first flow path 28 and the third flow path 32 are changed. Is connected to switch the open / close valve 22 to the closed state, and a change in the canister pressure Pc is detected between T9 and T10. Further, at time T10, the switching valve 34 is switched to the open state to connect the first flow path 28 and the second flow path 30, and the open / close valve 22 is switched to the open state to switch the canister pressure between T10 and T11. Pc is detected and set as the reference pressure (second negative pressure) again.

  Then, as shown in FIG. 5A, if the canister pressure Pc detected between T9 and T10 is smaller than the reference pressure (second negative pressure) detected again between T10 and T11, that is, the reference pressure ( If the negative pressure is greater than the second negative pressure), it can be determined that there is no leak in the canister 12. As a result, it can be determined that a leak has occurred on the fuel tank 101 side with respect to the on-off valve 22. As shown in FIG. 5B, if the canister pressure Pc is larger than the reference pressure (second negative pressure) detected again between T10 and T11, that is, it is more negative than the reference pressure (second negative pressure). If the pressure is small, it is determined that the canister 12 has a hole larger than the inner diameter of the reference orifice 40. That is, it is determined that there is a leak on the canister 12 side with respect to the open / close valve 22.

  In the present embodiment, as described above, when it is determined by the first pre-determination that there is a possibility that a leak has occurred somewhere in the fuel tank 101, the purge pipe 14, and the vapor pipe 16, The first and second determinations described above are executed without executing the second pre-determination. In this case, there is a possibility that a leak has occurred somewhere in the purge piping 14 and the vapor piping 16, and if the first pre-determination is correct, as shown in FIG. 6, T7-T8 based on the third determination is performed. The change in the canister pressure Pc during the period becomes smaller than the reference pressure (first negative pressure) detected again between T9 and T10. If the canister pressure Pc is smaller than the reference pressure (first negative pressure), that is, if the negative pressure is larger than the reference pressure (first negative pressure), the tank pressure sensor 17 or the like used for the first pre-determination is used. It can be determined that there is an abnormality.

  Further, the second determination is performed, and if the canister pressure Pc detected between T9 and T10 is smaller than the reference pressure (second negative pressure) detected again between T10 and T11 as shown in FIG. If the negative pressure is greater than the reference pressure (second negative pressure), it can be determined that there is no leak in the canister 12. As a result, it can be confirmed that a leak has occurred on the fuel tank 101 side than the on-off valve 22. At this time, if the canister pressure Pc is larger than the reference pressure (second negative pressure) detected again between T10 and T11, that is, if the negative pressure is smaller than the reference pressure (second negative pressure), the purge pipe 14 In addition, it can be determined that a leak has occurred somewhere in the vapor pipe 16, and it can be determined that there is also a leak on the canister 12 side.

  As described above, in the present invention, the first determination and the second determination are appropriately executed to determine whether or not there is a leak of fuel evaporative gas. As a result, the presence or absence of a leak can be accurately determined, and the leak location can be specified to some extent. In the present embodiment, since the pre-determination (first pre-determination and second pre-determination) is executed prior to the first determination, it is possible to more appropriately determine whether or not there is a leak and the leak location. it can. Further, since the pre-determination is executed in a state where the negative pressure pump 36 is stopped, the power consumption consumed in the leak determination can be suppressed.

  Furthermore, in the present invention, the presence or absence of a leak is determined based on the amount of change in tank pressure or canister pressure. For this reason, if an abnormality occurs in the tank pressure sensor 17 or the canister pressure sensor 42 and the tank pressure or the canister pressure does not change, the sensor abnormality can be easily detected.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The present invention can be modified as appropriate without departing from the spirit of the present invention.

  For example, in the above-described embodiment, a negative pressure pump that generates a negative pressure in the canister is used as the pressure generation unit, and the reference pressure in the first and second determinations is a negative pressure. However, a canister is added as the pressure generation unit. A reference pressure in the first and second determinations can be set to a positive pressure using a pressurizing pump that pressurizes (generates a positive pressure).

  For example, in the above-described embodiment, as the first pre-determination, when the tank pressure is a positive pressure, the presence / absence of a leak is determined based on whether or not the tank pressure has dropped below a predetermined threshold. However, in the first pre-determination, it can be determined that there is a possibility of leakage when the absolute value of the change amount of the tank pressure exceeds a predetermined value. Therefore, for example, when the tank pressure is negative, it can be determined that there is a possibility of leakage when the tank pressure rises above a predetermined threshold. Furthermore, although the above-mentioned embodiment demonstrated the example which performed the pre-determination prior to the 1st determination, this pre-determination does not necessarily need to be performed. Even when the pre-determination is not executed, the presence / absence of a leak can be appropriately determined by executing the first determination and the second determination.

10 Fuel Evaporative Gas Emission Suppressor 12 Canister 14 Purge Pipe (First Communication Path)
16 Vapor piping (second communication path)
16a connection part 17 tank pressure sensor (tank pressure detection part)
18 Purge valve (first opening / closing part)
20 Sealing valve (second opening / closing part)
22 Open / close valve (third open / close part)
24 Vent piping (third communication path)
26 Evaporative Leak Check Module (ELCM)
28 1st flow path 30 2nd flow path 32 3rd flow path 34 Switching valve (4th opening-closing part)
36 Negative pressure pump (pressure generator)
38 Fourth flow path 40 Reference orifice 42 Canister pressure sensor (canister pressure detector)
50 ECU
51 Determination Unit 100 Engine 101 Fuel Tank 102 Intake Passage

Claims (6)

A first communication passage communicating the intake passage of the vehicle engine and the canister;
A second communication path communicating the canister and the fuel tank;
A third communication path communicating the canister and the outside air;
A first opening / closing part provided in the first communication path to open and close the first communication path;
A second opening / closing portion provided in the second communication path to open and close the second communication path;
A third opening / closing part that is provided closer to the canister than a connection part between the second communication path and the first communication path and opens and closes the first communication path;
A fourth opening / closing portion provided in the third communication path to open and close the third communication path;
A pressure generating section for generating pressure in the canister via the third communication path;
A canister pressure detector for detecting the pressure in the canister;
When pressure is generated in the canister by the pressure generator with the first opening / closing part closed, the second and third opening / closing parts open, and the fourth opening / closing part closed. Performing a first determination for determining whether or not there is a leak of fuel evaporative gas based on the detection result of the canister pressure detection unit,
If it is determined by this first determination that there is a leak of fuel evaporative gas, the canister pressure detection when pressure is generated in the canister with the third opening / closing portion switched from open to closed. A fuel evaporative emission control apparatus, comprising: a determination unit that performs a second determination for determining whether or not there is a leak of the fuel evaporative gas based on a detection result of the unit. The fuel evaporative emission control device according to claim 1,
The determination unit
A fuel evaporative emission control device, wherein when performing the first determination, it is determined that there is a leak if the detection result of the canister pressure detection unit does not reach a preset first pressure. The fuel evaporative emission control device according to claim 1 or 2,
The determination unit
When performing the second determination,
When the detection result of the canister pressure detection unit does not reach a preset second negative pressure, it is determined that a leak has occurred on the canister side with respect to the third opening / closing unit,
When the detection result of the canister pressure detection unit exceeds the second pressure, it is determined that a leak has occurred on the fuel tank side than the third opening / closing unit. Gas emission control device. In the fuel evaporative emission control device according to any one of claims 1 to 3,
A tank pressure detector for detecting the pressure in the fuel tank;
The determination unit
Prior to the first determination, a pre-determination that determines whether or not there is a leak of fuel evaporative gas based on the detection results of the canister pressure detection unit and the tank pressure detection unit,
The fuel evaporative emission control device, wherein the first determination is executed when it is not determined that there is no leakage of the fuel evaporative gas by the pre-determination. The fuel evaporative emission control device according to claim 4,
The determination unit
When performing the pre-determination,
When the pressure of the fuel tank when the second opening / closing part is opened and the first and third opening / closing parts are closed falls to a first threshold value set in advance within a predetermined time,
Alternatively, even when the pressure of the fuel tank when the second opening / closing part is opened and the first and third opening / closing parts are closed does not drop to the first threshold value set in advance within a predetermined time, When the second opening / closing part is opened, the first and fourth opening / closing parts are closed, and the pressure generating part is stopped, the third opening / closing part is switched from closed to open. When the pressure does not rise or fall to the preset second threshold within a predetermined time,
A fuel evaporative emission control device that performs the first determination without determining that there is no leakage of fuel evaporative gas. The fuel evaporative emission control device according to claim 4 or 5,
The fuel evaporative emission control apparatus, wherein the second determination is executed without executing the first determination when it is determined that there is no leakage of the fuel evaporative gas according to the pre-determination.

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