JP6323647B2 - Fuel evaporative emission control device - Google Patents

Description

  The present invention relates to a fuel evaporative emission control device, and more particularly to an abnormality detection technique for a fuel evaporative emission control device.

  Conventionally, in order to prevent the fuel evaporating gas evaporated in the fuel tank from being released to the atmosphere, the canister that is provided in the communication passage that connects the fuel tank and the intake passage of the internal combustion engine, and the fuel tank and the canister are communicated with each other. Alternatively, there is provided a fuel evaporative emission control device comprising a sealing valve for blocking and a purge valve for communicating and blocking the communication passage between the intake passage and the canister. The fuel evaporative emission control device opens the sealing valve and closes the purge valve when refueling, so that the fuel evaporative gas in the fuel tank flows out to the canister, and the fuel evaporative gas is adsorbed to the activated carbon provided in the canister. ing. The fuel evaporative emission control device opens the purge valve during operation of the internal combustion engine and discharges the fuel evaporative gas adsorbed on the activated carbon of the canister to the intake passage of the internal combustion engine to process the fuel evaporative gas (canister purge).

Further, in the fuel tank sealed by the sealing valve in this way, when the pressure in the fuel tank becomes high, the purge valve and the sealing valve are opened during operation of the internal combustion engine, and the fuel evaporative gas in the fuel tank is removed. The fuel evaporative gas in the fuel tank and the communication passage is processed by discharging into the intake passage (tank purge).
Furthermore, there has been proposed a fuel evaporative emission control device capable of performing a purge flow monitor for determining whether or not canister purge is normally performed (whether or not the purge function is normal).

  The purge flow monitor, for example, determines that the purge process is possible when the internal pressure of the internal combustion engine is closed and the purge valve is opened and the pressure in the canister drops more than a predetermined value (Patent Document). 1).

JP 2005-256624 A

By the way, as described above, there is known a fuel evaporative emission control device equipped with a canister, further comprising a canister opening / closing valve for opening and closing the communication passage and the canister.
By providing the canister opening / closing valve in this way and closing the canister opening / closing valve at the time of tank purge, it is possible to prevent the fuel evaporative gas in the tank from adsorbing to the canister.
However, in the fuel evaporative emission control device having the canister opening / closing valve as described above, even if the sealing valve is closed, the purge flow monitoring is impossible if the canister opening / closing valve is closed.

  The present invention has been made to solve such problems, and an object of the present invention is to enable a purge flow monitor with a simple configuration in a fuel evaporative emission control device having a canister on-off valve. There is.

In order to achieve the above object, a fuel evaporative emission control device according to claim 1 is a communication passage that communicates an intake passage of an internal combustion engine and a fuel tank, and fuel evaporation in the communication passage is connected to the communication passage. A canister for adsorbing gas; a canister opening / closing valve for opening / closing communication between the communication passage and the canister; a purge valve for opening / closing the communication passage between the intake passage and the canister; and the fuel tank. A sealing valve that opens and closes so as to open or block the passage; a pressure detector that detects an internal pressure of the canister; and the sealing valve is closed during operation of the internal combustion engine to open the canister opening and closing valve and the purge valve. A canister purge control unit for executing a canister purge for discharging the fuel evaporative gas adsorbed by the canister to the intake passage and supplying the fuel evaporative gas to the internal combustion engine; During the operation of the valve, the sealing valve is closed, the purge valve and the canister on-off valve are opened, and the function determination of the canister purge is performed based on the change in the internal pressure of the canister detected by the pressure detection unit. A purge function determination unit , wherein the canister purge by the canister purge control unit is regulated so that a water temperature of the internal combustion engine is lower than a first predetermined temperature, and the function determination of the canister purge by the purge function determination unit is The temperature is regulated below a second predetermined temperature lower than the first predetermined temperature .

According to a second aspect of the present invention, there is provided the fuel evaporative emission control device according to the first aspect, wherein after the start of the internal combustion engine, the canister purge is restricted until the canister purge function determination by the purge function determining section is completed. It is characterized by having a regulation part .

According to a third aspect of the present invention, there is provided the fuel evaporative emission control device according to the first or second aspect, wherein the sealing valve is closed during the operation of the internal combustion engine before the purge function determination unit determines the function of the canister purge. A purge valve failure determination unit that opens the canister on-off valve, controls the closing of the purge valve, and detects the open adhering of the purge valve based on a change in the internal pressure of the canister detected by the pressure detection unit. It is characterized by having.

According to a fourth aspect of the present invention, there is provided the fuel evaporative emission control device according to any one of the first to third aspects, wherein the canister on-off valve is closed and the sealing valve and the purge valve are opened during operation of the internal combustion engine. And a tank purge control unit that executes a tank purge that discharges fuel evaporative gas in the fuel tank to the intake passage and supplies it to the internal combustion engine, and the tank purge by the tank purge control unit is executed. And a purge function determination restricting unit that restricts the function determination of the canister purge by the purge function determining unit until a predetermined time elapses after the canister opening / closing valve is switched from closed to open. .

According to the first aspect of the present invention, the canister purge function can be determined based on the detection result of the pressure detection unit, and an additional sensor or the like is not required, thereby preventing the system from becoming complicated.
Further, the canister purge function can be determined after the internal combustion engine is started from a lower water temperature than the canister purge. Therefore, the canister purge function determination can be performed immediately after the engine is started to perform the canister purge, so that the series of purge processes after the engine is started can be quickly terminated.
According to the second aspect of the present invention, since the canister purge is restricted until the canister purge function determination is completed, the canister purge can be performed after it is determined that the canister purge function is normal. Only purging can be performed.

According to the invention 請 Motomeko 3, it is possible to detect the open sticking of the purge valve before the function determination of the canister purge is possible not to perform the canister purge when the purge valve is stuck open state it can. Accordingly, it is possible to prevent the function determination of the useless canister purge when the purge valve is in a failure state.

According to the fourth aspect of the invention, by limiting the function determination of the canister purge when the canister opening / closing valve is closed, the function determination of the canister purge is controlled when the tank purge is executed. Thereby, it is possible to determine the function of the canister purge while avoiding the influence of the pressure in the fuel tank. In addition, since the canister purge function judgment is restricted until a predetermined time has elapsed since the canister on / off valve was switched from closed to open, the canister on / off valve was switched from closed to open at the end of the tank purge. The canister purge function determination can be performed with good timing after the pressure in the canister is stabilized later, and the accuracy of the canister purge function determination can be improved.

1 is a schematic configuration diagram of a fuel evaporative emission control device according to an embodiment of the present invention. It is a figure which shows the action | operation of the internal component at the time of the non-operation of the switching valve of an evaporative leak check module. It is a figure which shows the action | operation of an internal component at the time of the action | operation of the switching valve of an evaporative leak check module. It is a part of flowchart which shows the control procedure of the purge flow monitor which ECU of this embodiment performs. It is the remainder of the flowchart which shows the control procedure of the purge flow monitor which ECU of this embodiment performs. It is a time chart which shows an example of transition of a drive signal of a bypass valve, operation of each valve, each timer, and canister pressure deviation at the time of purge valve normality and purge function abnormality. It is a time chart which shows an example of change of a drive signal of a bypass valve, operation of each valve, each timer, and canister pressure deviation at the time of purge valve normal and purge function normal. It is a time chart which shows an example of change of a drive signal of a bypass valve, operation of each valve, each timer, and canister pressure deviation when it is judged with open sticking.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fuel evaporative emission control device 1 according to an embodiment of the present invention. 2 is a diagram showing the operation of the internal components when the switching valve 34e of the evaporative leak check module 34 is not operated, and FIG. 3 is a diagram when the switching valve 34e of the evaporative leak check module 34 is operated. It is a figure which shows the action | operation of an internal component. The arrows in FIGS. 2 and 3 indicate the air flow direction when the negative pressure pump 34c in the evaporative leak check module 34 is operated in the state shown in the figure. Note that the switching valve 34e is in an open state when not in operation in FIG. 2, and is in a closed state when in operation in FIG. Hereinafter, the configuration of the fuel evaporative emission control device will be described.

The fuel evaporative emission control device 1 according to the present embodiment includes a travel motor and an engine 10 (internal combustion engine) (not shown), and is used for a hybrid vehicle or a plug-in hybrid vehicle that travels using one or both of them. Yes.
As shown in FIG. 1, the fuel evaporative emission control device 1 processes an engine 10 that is largely mounted on a vehicle, a fuel storage unit 20 that stores fuel, and fuel evaporative gas that has evaporated in the fuel storage unit 20. A fuel evaporative gas processing unit 30 and an electronic control unit (hereinafter referred to as ECU) 40 (canister purge control unit, tank purge control unit, purge function determination unit, purge function) which is a control device for performing overall control of the vehicle A judgment regulation unit, a canister purge regulation unit, and a purge valve failure judgment unit).

  The engine 10 is an intake passage injection (MPI) gasoline engine. The engine 10 is provided with an intake passage 11 that takes air into the combustion chamber of the engine 10. A fuel injection valve 12 that injects fuel into the intake port of the engine 10 is provided downstream of the intake passage 11. A fuel pipe 13 is connected to the fuel injection valve 12 and fuel is supplied from a fuel tank 21 that stores fuel.

An intake air temperature sensor 14 for detecting the temperature of the intake air is disposed in the intake passage 11 of the engine 10. Further, the engine 10 is provided with a water temperature sensor 15 that detects the temperature of cooling water that cools the engine 10.
The fuel storage unit 20 includes a fuel tank 21, a fuel filler port 22 that is a fuel inlet to the fuel tank 21, and a fuel pump 23 that supplies fuel from the fuel tank 21 to the fuel injection valve 12 via the fuel pipe 13. The fuel cut-off valve 24 prevents the fuel from flowing out from the fuel tank 21 to the fuel evaporative gas processing unit 30 and the leveling valve 25 controls the liquid level in the fuel tank 21 during refueling. The fuel evaporative gas generated in the fuel tank 21 is discharged from the fuel cut-off valve 24 to the fuel evaporative gas processing unit 30 via the leveling valve 25.

The fuel evaporative gas processing unit 30 includes a purge pipe 31 (communication path), a vapor pipe 32 (communication path), a canister 33, an evaporative leak check module 34, a sealing valve 35, and a purge valve 36 (purge valve). , A bypass valve 37 (canister on-off valve) and a pressure sensor 38.
The purge pipe 31 is provided so as to communicate the intake passage 11 of the engine 10 and the canister 33.

The vapor pipe 32 is provided so as to communicate the leveling valve 25 of the fuel tank 21 and the purge pipe 31. That is, the vapor pipe 32 is provided so as to communicate the fuel tank 21 and the purge pipe 31.
The canister 33 has activated carbon inside. A purge pipe 31 is connected to the canister 33 so that fuel evaporative gas generated in the fuel tank 21 or fuel evaporative gas adsorbed on the activated carbon can flow. Further, the canister 33 is provided with an air hole 33 a for sucking outside air when the fuel evaporative gas adsorbed on the activated carbon is discharged to the intake passage 11 of the engine 10.

  As shown in FIGS. 2 and 3, the evaporative leak check module 34 is provided with a canister-side passage 34 a that communicates with the atmosphere hole 33 a of the canister 33 and an atmosphere-side passage 34 b that communicates with the atmosphere. A pump passage 34d including a negative pressure pump 34c communicates with the atmosphere side passage 34b. Further, the evaporative leak check module 34 is provided with a switching valve 34e and a bypass passage 34f. The switching valve 34e includes an electromagnetic solenoid and is driven by the electromagnetic solenoid. When the electromagnetic solenoid is in a non-energized state (OFF), the switching valve 34e causes the canister side passage 34a and the atmosphere side passage 34b to communicate with each other as shown in FIG. 2 (corresponding to the open state of the switching valve 34e). Further, when the drive signal is supplied to the electromagnetic solenoid from the outside and the energization state is ON (ON), the switching valve 34e causes the canister side passage 34a and the pump passage 34d to communicate with each other as shown in FIG. Equivalent to a closed state). The bypass passage 34f is a passage that always connects the canister side passage 34a and the pump passage 34d. The bypass passage 34f is provided with a reference orifice 34g having a small diameter (for example, a diameter of 0.45 mm). Further, between the negative pressure pump 34c of the pump passage 34d and the reference orifice 34g of the bypass passage 34f, a pressure sensor 34h (pressure detector) that detects the pressure in the bypass passage 34f downstream of the pump passage 34d or the reference orifice 34g. Is provided.

The pressure sensor 34 h detects a canister internal pressure that is an internal pressure of the canister 33.
The sealing valve 35 is interposed in a vapor pipe 32 between the fuel tank 21 and the purge pipe 31. The sealing valve 35 includes an electromagnetic solenoid and is driven by the electromagnetic solenoid. The normally closed solenoid valve 35 is closed when the electromagnetic solenoid is not energized (OFF), and is opened when a drive signal is supplied to the solenoid from the outside to be energized (ON). It is. The sealing valve 35 seals the vapor pipe 32 when the electromagnetic solenoid is in a non-energized state (OFF) and closes the vapor pipe 32, and is supplied with a drive signal from the outside and opened in the energized state (ON). If there is, the vapor pipe 32 is opened. That is, the sealing valve 35 seals the fuel tank 21 in a closed state when the valve is closed, and makes it impossible for the fuel evaporative gas generated in the fuel tank 21 to flow out into the canister 33 or the intake passage 11 of the engine 10. If the valve is open, the fuel evaporative gas can flow out into the canister 33 or the intake passage 11 of the engine 10.

  The purge valve 36 is interposed in the purge pipe 31 between the intake passage 11 and the connection portion of the vapor pipe 32 of the purge pipe 31. The purge valve 36 includes an electromagnetic solenoid and is driven by the electromagnetic solenoid. The purge valve 36 is a normally closed solenoid valve that is closed when the electromagnetic solenoid is not energized (OFF), and is opened when a drive signal is supplied to the electromagnetic solenoid from the outside and energized (ON). is there. The purge valve 36 closes the purge piping 31 when the electromagnetic solenoid is in a non-energized state (OFF) and is opened when the drive signal is supplied from the outside to the electromagnetic solenoid. If so, the purge pipe 31 is opened. That is, when the purge valve 36 is in the closed state, the fuel evaporative gas cannot flow out from the canister 33 or the fuel tank 21 to the intake passage 11 of the engine 10. The fuel evaporative gas can flow out to the ten intake passages 11.

  The bypass valve 37 is interposed in the purge pipe 31 between the connection part of the vapor pipe 32 of the purge pipe 31 and the canister 33. The bypass valve 37 includes an electromagnetic solenoid and is driven by the electromagnetic solenoid. The bypass valve 37 is a normally open solenoid valve that is opened when the electromagnetic solenoid is not energized (OFF), and is closed when a drive signal is supplied from the outside to the electromagnetic solenoid and energized (ON). It is. The bypass valve 37 opens the canister 33 to the purge pipe 31 when the electromagnetic solenoid is not energized (OFF) and is open (ON) when a drive signal is supplied from the outside to the electromagnetic solenoid. When the valve is closed, the canister 33 is blocked. That is, when the bypass valve 37 is in the closed state, the canister 33 is sealed, so that the fuel evaporative gas cannot flow into or out of the canister 33. If the bypass valve 37 is in the open state, the fuel evaporative gas can flow into the canister 33 or the fuel evaporative gas can flow out of the canister 33.

The pressure sensor 38 is disposed in the vapor pipe 32 between the fuel tank 21 and the sealing valve 35. The pressure sensor 38 detects a tank internal pressure that is an internal pressure of the fuel tank 21. The pressure sensor 38 can detect the internal pressure of only the fuel tank 21 only when the sealing valve 35 is in the closed state and the fuel tank 21 is sealed.
The ECU 40 is a control device for performing comprehensive control of the vehicle, and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), a timer, and the like. The

The intake air temperature sensor 14, the water temperature sensor 15, the pressure sensor 34h and the pressure sensor 38 are connected to the input side of the ECU 40, and detection information from these sensors is input.
On the other hand, the fuel injection valve 12, the fuel pump 23, the negative pressure pump 34c, the switching valve 34e, the sealing valve 35, the purge valve 36, and the bypass valve 37 are connected to the output side of the ECU 40.

  The ECU 40 controls the operation of the negative pressure pump 34c and the opening / closing of the switching valve 34e, the sealing valve 35, the purge valve 36, and the bypass valve 37 based on detection information from various sensors, and is generated in the fuel tank 21. Adsorption of the fuel evaporative gas to the canister 33 or a purge process (canister purge) for discharging the fuel evaporative gas adsorbed on the canister 33 during operation of the engine 10 or the fuel evaporative gas generated in the fuel tank 21 to the intake passage 11 of the engine 10 , Tank purge).

The canister purge is performed for a predetermined time immediately after the engine is started, for example.
In the canister purge, the ECU 40 opens the purge valve 36 and the bypass valve 37 during the engine operation (canister purge control unit). At this time, the sealing valve 35 is in a closed state, and the switching valve 34e is in an open state. As a result, the purge pipe 31 and the canister 33 communicate with the intake passage 11 of the engine 10, so that the atmosphere from the outside air intake port of the canister 33 enters the canister 33 and the purge pipe to the intake passage 11 that has become negative pressure due to the operation of the engine 10. It flows in through 31. Therefore, the fuel evaporative gas adsorbed by the canister 33 is discharged into the intake passage 11 and processed.

  The tank purge is performed until the pressure in the fuel tank 21 decreases when the pressure in the fuel tank 21 becomes a high pressure equal to or higher than the predetermined pressure P1 during the operation of the engine 10. As the tank purge, the ECU 40 opens the sealing valve 35 and the purge valve 36 and closes the bypass valve 37 (tank purge control unit). As a result, the fuel tank 21 communicates with the intake passage 11 of the engine 10 via the purge pipe 31 and the vapor pipe 32, so that the fuel pipe 21 passes the vapor pipe 32 to the intake passage 11 that has become negative pressure due to the operation of the engine 10. The fuel evaporative gas flows through the purge pipe 31. Accordingly, the fuel evaporative gas in the fuel tank 21 is discharged into the intake passage 11 for processing, and the pressure in the fuel tank 21 decreases. The tank purge is performed with priority over the canister purge. Accordingly, when the pressure in the fuel tank 21 is equal to or higher than the predetermined pressure P1 immediately after the engine is started, the canister purge is performed after the tank purge is performed.

Further, the ECU 40 can perform a purge flow monitor that determines whether or not canister purge is normally performed immediately after the engine is started.
The purge flow monitor is performed when the monitoring condition is satisfied immediately after the engine is started. The monitoring condition is that after the engine 10 is started, the throttle 55 is not fully opened (the throttle front-rear pressure ratio is equal to or lower than a predetermined value R1), the engine water temperature Tw is equal to or higher than the first predetermined temperature Tw1, and the like.

  4 and 5 are flowcharts showing the control procedure of the purge flow monitor executed by the ECU 40. FIG. 6 to 8 show the drive signals of the valves (sealing valve 35, purge valve 36, bypass valve 37, switching valve 34e) in the purge flow monitor, timers (prohibition timer after bypass valve opening, purge function monitor execution timer). , Purge valve monitor execution timer, purge valve monitor failure confirmation timer) operation, throttle front / rear pressure ratio, canister pressure deviation, and respective determination signals. FIG. 6 shows an example in which the purge valve 36 is not open and fixed and the purge function is abnormal. FIG. 7 shows an example in which the purge valve 36 is not open and fixed and the purge function is normal. FIG. 8 shows an example when the purge valve 36 is fixed open.

A control procedure of the purge flow monitor will be described with reference to FIGS.
The purge flow monitor is started after the engine 10 is started. Note that canister purge is prohibited from engine start.
As shown in FIGS. 4 and 5, first, in step S10, it is determined whether or not the monitor condition is satisfied for a predetermined time T1. If the monitoring condition is satisfied for a predetermined time T1, the process proceeds to step S20. If the monitoring condition is not satisfied for the predetermined time T1, the process returns to step S10.

  In step S20, a purge valve monitor is executed. The purge valve monitor is controlled by closing the purge valve 36 and opening the bypass valve 37, closing the switching valve 34e, and detecting the canister internal pressure P by the pressure sensor 34h. Specifically, first, the canister internal pressure P detected by the pressure sensor 34h at the start of the purge valve monitoring is stored as the reference pressure Pb. Then, while detecting the canister internal pressure P, the pressure deviation ΔP (= | P−Pb |) between the canister internal pressure P and the reference pressure Pb becomes equal to or greater than the predetermined value P2 before the predetermined time T2 elapses from the start of the purge valve monitoring. When the state continues for a predetermined time T3 or more, it is determined that the purge valve 36 is open and stuck. If the state in which the pressure deviation ΔP is equal to or greater than the predetermined value P2 does not continue for the predetermined time T3 before the predetermined time T2 elapses from the start of the purge valve monitoring, it is determined that the purge valve 36 is not stuck open and is normal. Then, the process proceeds to step S30.

In step S30, it is determined by the purge valve monitor in step S20 whether or not the purge valve 36 has been determined not to be stuck open. If it is determined that the purge valve 36 is not stuck open, the process proceeds to step S40. If it is determined that the purge valve 36 is stuck open, the process proceeds to step S150.
In step S40, the purge flow monitor (purge function monitor) is started. At the start of the purge flow monitoring, the switching valve 34e is closed, and the canister internal pressure P is detected by the pressure sensor 34h and stored as the reference pressure Pb. Then, the purge function monitor timer Tp is started from 0. Then, the process proceeds to step S50.

In step S50, it is determined whether the monitor condition is satisfied. If the monitor condition is satisfied, the process proceeds to step S60. If the monitor condition is not satisfied, the process proceeds to step S130.
In step S60, it is determined whether or not the bypass valve 37 is in a closed state, or whether or not the bypass valve 37 is switched from closed to open within a predetermined time T4. This determination is made by a prohibition timer after bypass valve opening. The bypass after-opening prohibition timer is set to 0 when the bypass valve 37 is opened, and is set to a predetermined time T4 when the bypass valve 37 is closed. When the bypass valve 37 is switched from the closed valve to the opened valve, the count starts so as to decrease from the predetermined time T4. If the count value of the prohibition timer after bypass valve opening is greater than 0, it is determined that the bypass valve 37 is in a closed state or the bypass valve 37 is switched from opening to closing within a predetermined time T4, Proceed to step S130. If the prohibition timer after bypass opening is 0, the process proceeds to step S70. Here, the predetermined time T4 may be set such that the pressure in the canister 33 is sufficiently stabilized after the bypass valve 37 is switched from the closed valve to the opened valve after the tank purge.

In step S70, the canister internal pressure P is detected by the pressure sensor 34h. Then, the process proceeds to step S80.
In step S80, a pressure deviation ΔP (= | P−Pb |) that is a difference between the canister internal pressure P detected in step S70 and the reference pressure Pb stored in step S40 is calculated. Then, the process proceeds to step S90.

  In step S90, it is determined whether or not the pressure deviation ΔP calculated in step S80 is equal to or greater than a predetermined pressure P3. As for the predetermined pressure P3, the internal pressure of the canister decreases due to the negative pressure of the intake passage 11 due to the engine operation, and a pressure deviation generated during a predetermined time T5 set as appropriate is measured in advance by an experiment or the like. You only have to set it. If the pressure deviation ΔP is greater than or equal to the predetermined pressure P3, the process proceeds to step S120. If the pressure deviation ΔP is less than the predetermined pressure P3, the process proceeds to step S100.

In step S100, it is determined whether or not the purge function monitor timer Tp is equal to or longer than the predetermined time T5. If the purge function monitor timer Tp is equal to or longer than the predetermined time T5, the process proceeds to step S110. If the purge function monitor timer Tp is less than the predetermined time T5, the process returns to step S50.
In step S110, it is determined that the purge function is abnormal, and the process proceeds to step S160.

In step S120, it is determined that the purge function is normal, and the process proceeds to step S160.
In step S130, the purge flow monitor is stopped. Specifically, the switching valve 34e is opened. Then, the process proceeds to step S140.
In step S140, as in step S10, it is determined whether or not the monitoring condition is satisfied for a predetermined time T1 or more. If the monitoring condition is satisfied for a predetermined time T1 or longer, the process returns to step S40. If the monitoring condition has not been satisfied for a predetermined time T1 or longer, the process returns to step S140.

In step S150, it is determined that the purge valve 36 is open and stuck, and the process proceeds to step S160.
In step S160, the purge flow monitoring is completed after a predetermined time T6 has elapsed. The predetermined time T6 is set to confirm that the purge flow monitor has been completed with certainty. When the purge flow monitor is completed, the prohibition of canister purge is released. Then, this routine ends.

  The purge valve monitor in step S20 corresponds to the purge valve failure determination unit of the present invention, the control from S40 to S120 corresponds to the purge function determination unit of the present invention, and the control of steps S60 and S130 is the purge of the present invention. Corresponds to the function judgment regulation section. Further, the prohibition of canister purge from the start of the engine to the cancellation in step S160 corresponds to the canister purge restriction unit.

As described above, in the present embodiment, the process starts when the purge flow monitor monitoring condition is satisfied. First, the purge valve monitor is executed to determine whether or not the purge valve 36 is in the open fixing state.
The purge valve monitor controls the closing of the purge valve 36 and opens the bypass valve 37 as described above, and closes the switching valve 34e and detects the pressure in the canister 33 by the pressure sensor 34h. If the pressure deviation ΔP in the canister 33 does not reach the predetermined value P2 even if the predetermined time T2 elapses, the purge valve 36 is not fixed open, and the pressure deviation ΔP in the canister 33 is predetermined before the predetermined time T2 elapses. When the value P2 or more is reached and this continues for a predetermined time T3 or more, it is determined that the purge valve 36 is fixed open. The predetermined value P2 may be set to a value that does not reach (does not decrease) even if the engine T2 is operated for a predetermined time T2 appropriately set when the purge valve 36 is closed. The predetermined time T3 is set to avoid erroneous detection due to fluctuations in the intake pressure.

  Even if the intake passage 11 becomes negative pressure due to the operation of the engine 10, the purge valve 36 is controlled to be closed. Therefore, if the purge valve 36 is normally closed, the pressure in the canister 33 does not change (decrease). However, when the pressure in the canister 33 changes (decreases), the pressure in the canister 33 is reduced by the negative pressure in the intake passage 11, and the purge valve 36 is controlled to be closed. It is presumed that the purge valve 36 is open, and therefore it can be determined that the purge valve 36 is in the open fixed state.

When the purge valve monitor determines that the purge valve 36 is not in the open fixed state, the purge flow monitor is performed.
In the purge flow monitor, the pressure deviation ΔP became equal to or greater than the predetermined value P3 by the time when the purge valve 36 was opened and the predetermined time T5 passed while the switching valve 34e and the sealing valve 35 were closed and the bypass valve 37 was opened. If the pressure deviation ΔP does not exceed the predetermined value P3 even after the predetermined time T5 has elapsed, it is determined that there is an abnormality. This controls the sealing valve 35, the purge valve 36, and the bypass valve 37 so that the canister purge is actually performed, and the switching valve 34e is closed to detect the pressure in the canister 33, and the pressure deviation ΔP in the canister 33 is detected. Is increased by a predetermined value P3 or more, that is, when the pressure is decreased by a predetermined value P3 or more by the negative pressure in the intake passage 11, it is confirmed that canister purge is possible.

In the present embodiment, the purge flow monitor is immediately stopped when the bypass valve 37 is closed. This is because the canister 33 is closed when the bypass valve 37 is closed, so that the purge flow monitor that is determined based on the change in the pressure in the canister 33 caused by the negative pressure in the intake passage 11 becomes impossible. Because.
Further, in this embodiment, even if the tank purge is finished and the bypass valve 37 is opened, the purge flow monitoring is not started immediately. This is because the pressure may increase due to the fuel evaporative gas remaining in the purge pipe 31 immediately after completion of the tank purge, and when the purge flow monitor is restarted immediately after the bypass valve 37 is opened by the completion of the tank purge. This is because high-pressure fuel evaporative gas may remain in the communication path, and the pressure in the canister 33 may fluctuate due to the pressure in the purge pipe 31 and the purge flow monitor may not be properly determined. In particular, in the present embodiment, since the purge flow monitoring can be started when a predetermined time T4 has elapsed since the bypass valve 37 was opened, the purge flow is based on the opening and closing timing of the bypass valve 37 that opens and closes near the pressure sensor 34h. By setting the timing to start monitoring, the timing at which the pressure fluctuation in the canister 33 is settled can be set more accurately. Accordingly, by shortening the purge flow monitor completion time T6 as much as possible and ending the purge flow monitor sooner after the engine 10 is started, the purge flow monitor can be used even for a vehicle such as a plug-in hybrid with a low engine start frequency. The frequency of monitoring can be improved. This quickly detects faults that may affect the atmosphere and improves environmental performance.

Further, in the present embodiment, the prohibition of canister purge is released after the purge flow monitor ends. In this way, by restricting the canister purge during the purge flow monitoring, the canister purge is performed after it is determined that the function of the canister purge is sufficient, and only an appropriate canister purge can be performed.
In addition, by performing a purge valve monitor before the purge flow monitor and performing the purge flow monitor when the purge valve is not in the open fixed state, it is possible to execute a wasteful purge flow monitor when the purge valve is in the open fixed state. Can be prevented.

  Further, the monitoring condition that is the execution condition of the purge flow monitor includes that the engine water temperature is equal to or higher than the second predetermined temperature Tw2, and the execution temperature of the canister purge is equal to or higher than the first predetermined temperature Tw1. Is included. Then, the second predetermined temperature Tw2 that is the threshold value of the engine water temperature that is the execution condition of the purge flow monitor is set to a temperature that is lower than the first predetermined temperature Tw1 that is the threshold value of the engine water temperature that is the execution condition of the canister purge. The purge flow monitor may be restricted when the engine water temperature is lower than the second predetermined temperature Tw2. This enables the purge flow monitor from a lower water temperature than the canister purge after engine startup. Therefore, the purge flow monitoring can be performed immediately after the engine is started and the process can be quickly terminated to shift to the canister purge, and the purge process after the engine is started can be quickly terminated.

This is the end of the description of the embodiment of the invention. However, the embodiment of the present invention is not limited to the above embodiment, and the purge flow monitor may be regulated based on at least the opening / closing of the bypass valve 37 as described above. .
In the above embodiment, the vehicle is a hybrid vehicle. However, the present invention is not limited to this, and is widely used in a fuel evaporative emission control device having a bypass valve 37 and capable of purge flow monitoring. The purge flow monitor may be regulated based on the above.

10 Engine (Internal combustion engine)
11 Intake passage 21 Fuel tank 31 Purge piping (communication passage)
32 Vapor piping (communication passage)
33 Canister 34h Pressure sensor (pressure detector)
35 Sealing valve 36 Purge valve (Purge valve)
37 Bypass valve (canister open / close valve)
40 ECU (canister purge control unit, tank purge control unit, purge function judgment unit, purge function judgment regulation unit, canister purge regulation unit, purge valve failure judgment unit)

Claims (4)

A communication passage communicating the intake passage of the internal combustion engine and the fuel tank;
A canister connected to the communication path and adsorbing fuel evaporative gas in the communication path;
A canister on-off valve that opens and closes communication between the communication passage and the canister;
A purge valve that opens and closes the communication path between the intake passage and the canister;
A sealing valve that opens and closes the fuel tank so as to open or block the communication passage;
A pressure detector for detecting the internal pressure of the canister;
During the operation of the internal combustion engine, the sealing valve is closed, the canister on-off valve and the purge valve are opened, and the fuel evaporative gas adsorbed by the canister is discharged to the intake passage and supplied to the internal combustion engine. A canister purge control unit for executing canister purge,
During the operation of the internal combustion engine, the sealing valve is closed, the purge valve and the canister on / off valve are opened, and the function determination of the canister purge is performed based on the change in the internal pressure of the canister detected by the pressure detection unit. A purge function determination unit for performing
With
The canister purge by the canister purge control unit is regulated such that the water temperature of the internal combustion engine is less than a first predetermined temperature, and the function determination of the canister purge by the purge function determination unit is lower than the first predetermined temperature. 2. A fuel evaporative emission control device, which is regulated at a temperature lower than a predetermined temperature of 2. 2. The fuel evaporative gas according to claim 1, further comprising a canister purge regulating unit that regulates the canister purge until the canister purge function judgment by the purge function judging unit is completed after the internal combustion engine is started. Emission control device.   Before determining the function of the canister purge by the purge function determining unit, during the operation of the internal combustion engine, the sealing valve is closed, the canister on-off valve is opened, the purge valve is closed, and the pressure is controlled. 3. The fuel evaporative emission control device according to claim 1, further comprising a purge valve failure determination unit that detects whether the purge valve is stuck open based on a change in internal pressure of the canister detected by the detection unit. . During operation of the internal combustion engine, the canister on-off valve is closed, the sealing valve and the purge valve are opened, and the fuel evaporative gas in the fuel tank is discharged to the intake passage and supplied to the internal combustion engine. A tank purge control unit for executing tank purge;
After the tank purge is performed by the tank purge control unit, the canister purge function determination by the purge function determination unit is regulated until a predetermined time has elapsed after the canister opening / closing valve is switched from the closed valve to the opened valve. The fuel evaporative emission control device according to any one of claims 1 to 3, further comprising a purge function determination restricting unit.

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