JP2005256624A - Evaporative fuel processing device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a purge flow accurately without being affected by pressure fluctuation due to opening of a blocking valve or a relief valve.
The detection of a purge flow based on the pressure in a gas passage is prohibited during the operation of the blocking valve, or during the operation of the blocking valve and until a predetermined time elapses after the operation. Alternatively, when the pressure Pt in the fuel tank is out of the pressure range in which the relief valve is securely closed, detection of the purge flow based on the pressure in the gas passage is prohibited.
[Selection] Figure 2

Description

  The present invention relates to an evaporative fuel processing apparatus for an internal combustion engine, and more particularly, to an evaporative fuel processing apparatus for supplying evaporative fuel generated in a fuel tank to a combustion chamber of the internal combustion engine without processing the evaporative fuel into the atmosphere.

  An internal combustion engine for a vehicle is provided with an evaporative fuel processing device for preventing evaporative fuel generated in a fuel tank from being released into the atmosphere. The evaporative fuel processing apparatus has a canister filled with activated carbon inside, and the evaporative fuel is adsorbed and stored in the canister. During the operation of the internal combustion engine, the evaporated fuel stored in the canister is purged from the canister using the negative pressure in the intake passage, is discharged into the intake passage together with fresh air, and is combusted in the combustion chamber.

The canister has recovered its adsorption performance by purging the evaporated fuel. If there is some abnormality in the evaporative fuel processing system (for example, the purge control valve is closed) and the purge is not performed normally, the adsorbed amount of evaporative fuel will eventually exceed the capacity of the canister. There is a possibility of evaporating fuel leaking from the air hole into the atmosphere. For this reason, in the evaporative fuel processing apparatus, for example, as disclosed in Patent Document 1, the purge flow is detected (air flow check) based on the pressure of the gas passage through which the gas flows along with the purge, and the purge is normally performed. Whether or not it is determined is determined.
JP-A-6-137222 JP 2002-349364 A Japanese Patent Laid-Open No. 10-61504 Japanese Patent Laid-Open No. 11-30157

  By the way, an evaporative fuel processing apparatus is known in which a fuel tank is sealed by interposing a sealing valve or a relief valve between a canister and a fuel tank. The block valve is normally closed and is opened when the tank internal pressure reaches a predetermined valve opening pressure. The relief valve automatically opens when the tank internal pressure exceeds a predetermined pressure range, thereby adjusting the tank internal pressure to a predetermined pressure range. In an apparatus including these block valves and relief valves, a pressure difference is generated between the pressure in the fuel tank and the pressure in the gas passage, so that the pressure in the gas passage varies with the opening of these valves. For this reason, if these valves are opened during the detection of the purge flow, the purge flow cannot be accurately detected due to the influence of fluctuations in the pressure of the gas passage.

  The present invention has been made to solve the above-described problems, and an evaporative fuel processing apparatus that can accurately detect a purge flow without being affected by pressure fluctuations due to the opening of a blocking valve or a relief valve. The purpose is to provide.

In order to achieve the above object, a first invention is an evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to an intake passage of the internal combustion engine, and a gas passage in which the canister is disposed midway,
A sealing valve disposed between the fuel tank and the canister;
Tank internal pressure control means for operating the block valve to control the pressure in the fuel tank;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
Detection prohibiting means for prohibiting detection of the purge flow by the purge flow detecting means during operation of the blocking valve, or until the predetermined time elapses during operation of the blocking valve and after operation;
It is characterized by having.

In order to achieve the above object, a second invention is an evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to an intake passage of the internal combustion engine, and a gas passage in which the canister is disposed midway,
A relief valve disposed between the fuel tank and the canister and opened when the pressure in the fuel tank is outside a predetermined first pressure range;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
Detection prohibiting means for prohibiting detection of a purge flow by the purge flow detecting means when the pressure in the fuel tank is outside a predetermined second pressure range included in the first pressure range;
It is characterized by having.

In order to achieve the above object, a third invention is an evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to an intake passage of the internal combustion engine, and a gas passage in which the canister is disposed midway,
A sealing valve disposed between the fuel tank and the canister;
Tank internal pressure control means for operating the block valve to control the pressure in the fuel tank;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
An operation prohibiting means for prohibiting the operation of the blocking valve by the tank internal pressure control means during detection of the purge flow by the purge flow detecting means;
It is characterized by having.

The fourth invention relates to the third invention, the operation prohibition releasing means for releasing the prohibition of the operation of the blocking valve by the operation prohibiting means when the pressure in the fuel tank is out of a predetermined pressure range,
Detection prohibiting means for prohibiting detection of purge flow by the purge flow detecting means when releasing the prohibition of operation of the blocking valve;
Is further provided.

  According to the first aspect of the invention, the detection of the purge flow is permitted after the block valve is operated or after a predetermined time has elapsed since the block valve is operated, and therefore, it is affected by the pressure fluctuation in the gas passage accompanying the block valve operation. The purge flow can be detected without any trouble. In particular, the detection of the purge flow is allowed after a predetermined time has elapsed after the operation of the block valve, so that even if a pressure pulsation remains in the gas passage after the block valve is operated, it is not affected. It becomes possible to detect the purge flow.

  According to the second invention, since the detection of the purge flow is permitted when the pressure in the fuel tank is in a pressure range where the relief valve does not open, the pressure fluctuation in the gas passage due to the sudden opening of the relief valve It becomes possible to detect the purge flow without being affected by the above.

  According to the third invention, since the operation of the block valve is prohibited during detection of the purge flow, it is possible to detect the purge flow without being affected by the pressure fluctuation in the gas passage accompanying the operation of the block valve. become.

  According to the fourth aspect of the present invention, when the pressure in the fuel tank is out of the predetermined pressure range, the prohibition of the operation of the block valve is released, and at that time, the detection of the purge flow is prohibited. It is possible to reduce the stress of the tank and to prevent the detection of the purge flow in a situation where the detection accuracy cannot be ensured such that the pressure in the gas passage varies with the operation of the block valve.

[Description of device configuration]
FIG. 1A is a diagram for explaining the configuration of the fuel vapor processing apparatus according to the embodiment of the present invention. As shown in FIG. 1A, the apparatus of this embodiment includes a fuel tank 10. The fuel tank 10 is provided with a tank internal pressure sensor 12 for measuring the tank internal pressure Pt. The tank internal pressure sensor 12 is a sensor that detects a tank internal pressure Pt as a relative pressure with respect to the atmospheric pressure and generates an output corresponding to the detected value. A liquid level sensor 14 for detecting the liquid level of the fuel is disposed inside the fuel tank 10.

  A vapor passage 20 is connected to the fuel tank 10 via ROV (Roll Over Valve) 16 and 18. The vapor passage 20 includes a blocking valve unit 24 in the middle thereof, and communicates with the canister 26 at the end thereof. The block valve unit 24 includes a block valve 28 and a relief valve 30. The block valve 28 is a normally closed electromagnetic valve that closes in a non-energized state and opens when a drive signal is supplied from the outside. The relief valve 30 includes a forward relief valve that opens when the pressure on the fuel tank 10 side is sufficiently higher than the pressure on the canister 26 side, and a reverse relief valve that opens in the opposite case. This is a mechanical two-way check valve.

  The canister 26 includes a purge hole 32. A purge passage 34 communicates with the purge hole 32. The purge passage 34 is provided with a purge valve (VSV: Vacuum Switching Valve) 36 in the middle thereof, and communicates with an intake passage 38 of the internal combustion engine at an end thereof. An air filter 40, an air flow meter 42, a throttle valve 44, and the like are provided in the intake passage 38 of the internal combustion engine. The purge passage 34 communicates with the intake passage 38 downstream of the throttle valve 44.

  The inside of the canister 26 is filled with activated carbon. The evaporated fuel flowing in through the vapor passage 20 is adsorbed by the activated carbon. The canister 26 also has an air hole 50. An atmospheric passage 54 communicates with the atmospheric hole 50 via a negative pressure pump module 52. The air passage 54 includes an air filter 56 in the middle thereof. The end of the atmospheric passage 54 is open to the atmosphere in the vicinity of the fuel filler port 58 of the fuel tank 10.

  As shown in FIG. 1, the evaporated fuel processing apparatus of this embodiment includes an ECU 60. The ECU 60 has a built-in soak timer for counting the elapsed time while the vehicle is parked. A lid switch 62 and a lid opener opening / closing switch 64 are connected to the ECU 60 together with the tank internal pressure sensor 12, the sealing valve 28, or the negative pressure pump module 52 described above. The lid opener opening / closing switch 64 is connected to a lid manual opening / closing device 66 by a wire.

  The lid opener opening / closing switch 64 is a locking mechanism for a lid (vehicle body lid) 68 that covers the fuel filler opening 58. When a lid opening signal is supplied from the ECU 60, or when the lid manual opening / closing device 66 is opened. When the operation is performed, the lid 68 is unlocked. The lid switch 62 connected to the ECU 60 is a switch for sending a command for releasing the lock of the lid 68 to the ECU 60.

  FIG. 1B is an enlarged view for explaining details of the negative pressure pump module 52 shown in FIG. The negative pressure pump module 52 includes a canister-side passage 70 that communicates with the air hole 50 of the canister 26 and an atmosphere-side passage 72 that communicates with the atmosphere. A pump passage 78 including a pump 74 and a check valve 76 communicates with the atmosphere side passage 72.

  The negative pressure pump module 52 also includes a switching valve 80 and a bypass passage 82. The switching valve 80 communicates the canister-side passage 70 with the atmosphere-side passage 72 in a non-energized state (OFF state), and pumps the canister-side passage 70 in a state where an external drive signal is supplied (ON state). The passage 78 is communicated. The bypass passage 82 is a passage through which the canister-side passage 70 and the pump passage 78 are electrically connected, and a 0.5 mm diameter reference orifice 84 is provided in the middle thereof.

  The negative pressure pump module 52 further incorporates a pump module pressure sensor 86. According to the pump module pressure sensor 86, the pressure inside the pump passage 78 can be detected on the check valve 76 side of the check valve 76.

[Description of basic operation]
Next, the basic operation of the evaporated fuel processing apparatus of this embodiment will be described.
(1) During parking In principle, the fuel vapor processing apparatus of the present embodiment maintains the closing valve 28 in the closed state while the vehicle is parked. When the blocking valve 28 is closed, the fuel tank 10 is cut off from the canister 26 as long as the relief valve 30 is closed. Therefore, in the evaporated fuel processing apparatus of this embodiment, the evaporated fuel is newly adsorbed to the canister 26 while the vehicle is parked unless the tank internal pressure Pt exceeds the positive valve opening pressure (positive pressure) of the relief valve 30. Never happen. Further, as long as the tank internal pressure Pt does not fall below the reverse valve opening pressure (negative pressure) of the relief valve 30, air is not sucked into the fuel tank 10 while the vehicle is parked.

(2) During refueling In the apparatus of the present embodiment, when the lid switch 62 is operated while the vehicle is stopped, the ECU 60 is activated, and the block valve 28 is first opened. At this time, if the tank internal pressure Pt is higher than the atmospheric pressure, the block valve 28 is opened, and at the same time, the evaporated fuel in the fuel tank 10 flows into the canister 26 and is adsorbed by the activated carbon therein. As a result, the tank internal pressure Pt decreases to near atmospheric pressure.

  When the tank internal pressure Pt decreases to near atmospheric pressure, the ECU 60 issues a command to the lid opener 64 to release the lock of the lid 68. The lid opener 64 receives the command and releases the lock of the lid 68. As a result, in the apparatus according to the present embodiment, the lid 68 can be opened after the tank internal pressure Pt reaches a value near atmospheric pressure.

  When the opening operation of the lid 68 is permitted, the lid 68 is opened, then the tank cap is opened, and then fuel supply is started. Since the tank internal pressure Pt is reduced to near atmospheric pressure before the tank cap is opened, the evaporated fuel is not released from the fuel filler port 58 to the atmosphere in accordance with the opening operation.

  The ECU 60 keeps the blocking valve 28 in an open state until refueling is completed (specifically, until the lid 68 is closed). For this reason, when refueling, the gas in the tank can flow out to the canister 26 through the vapor passage 20, and as a result, good refueling properties are ensured. At this time, the evaporative fuel flowing out is adsorbed by the canister 26 and therefore is not released to the atmosphere.

(3) During traveling When the vehicle is traveling, control for purging the evaporated fuel adsorbed by the canister 26 is executed when a predetermined purge condition is satisfied. Specifically, in this control, the purge valve 36 is appropriately duty-driven while the switching valve 80 is turned OFF and the atmospheric hole of the canister 26 is opened to the atmosphere. When the purge valve 36 is driven with a duty, the intake negative pressure of the internal combustion engine 10 is guided to the purge hole 32 of the canister 26. As a result, the evaporated fuel in the canister 26 is discharged into the intake passage 38 of the internal combustion engine together with the air sucked from the air hole 50.

  When a predetermined detection condition is satisfied, detection of a purge flow for determining whether or not the purge is normally performed is executed. Purge is performed by applying a negative pressure of the intake passage 38 to the canister 26. If purging is normally performed at this time, a series of gas passages connected from the atmospheric passage 54 to the purge passage 34 through the canister 26 There is a gas flow inside. When there is no gas flow, there is no pressure difference in the gas passage. On the other hand, when gas is flowing in the gas passage, the gas flow rate is adjusted before and after the ventilation resistance existing in the passage. There is a corresponding pressure loss. Therefore, the flow of gas in the gas passage, that is, the purge flow can be detected by detecting the pressure in the gas passage at the time of purging.

  In the apparatus of this embodiment, the purge flow is detected using the negative pressure pump module 52. When the switching valve 80 of the negative pressure pump module 52 is in a non-energized state (OFF) and the canister side passage 70 is communicated with the atmosphere side passage 72, the canister 26 and the atmosphere passage 54 are in communication. In this state, when the purge valve 36 is driven by a duty, the negative pressure of the intake passage 38 acts on the canister 26, and fresh air is introduced into the canister 26 from the open end of the atmospheric passage 54. At this time, in the atmospheric passage 54, pressure loss occurs before and after the air filter 56 provided in the middle, and the pressure on the downstream side of the air filter 56 is lower than the pressure at the open end of the atmospheric passage 54, that is, atmospheric pressure. . When the pressure on the downstream side of the air filter 56 decreases, the pressure in the pump passage 78 in the negative pressure pump module 52 also decreases. Therefore, the purge flow is detected by detecting the pressure in the pump passage 78 at the time of purging. Can do.

  The ECU 60 detects the pressure in the pump passage 78 at the time of purging by the pump module pressure sensor 86, and detects the purge flow based on the detection result. Specifically, if the detection value of the pump module pressure sensor 86 is not more than a predetermined determination value lower than the atmospheric pressure, it is determined that the purge is normal, and if it exceeds the determination value, it is determined as abnormal.

  Furthermore, in the apparatus of the present embodiment, during the traveling of the vehicle, the block valve 28 is opened so that the tank internal pressure Pt is maintained near the atmospheric pressure for the purpose of shortening the pressure release time before refueling. However, the valve opening is performed only during the purge of the evaporated fuel, that is, only when the intake negative pressure is introduced into the purge hole 32 of the canister 26. Under the condition where intake negative pressure is introduced to the purge hole 32, the evaporated fuel flowing from the fuel tank 10 into the canister 26 flows out of the purge hole 32 without entering deeply into the canister 26, and is then discharged to the intake passage 38. Is done. Therefore, according to the apparatus of the present embodiment, a large amount of evaporated fuel is not newly adsorbed by the canister 26 while the vehicle is traveling.

[Detailed description of operation when detecting purge flow]
In the fuel storage device according to the present embodiment, as described above, the purge flow is detected while the vehicle is running, and the internal pressure control of the fuel tank 10 is also performed by operating the block valve 28. However, if the detection of the purge flow and the operation of the blocking valve 28 are combined, the purge flow cannot be accurately detected due to the influence of the pressure fluctuation in the gas passage accompanying the operation of the blocking valve 28. The relief valve 30 provided in parallel with the blocking valve 28 is automatically opened when the tank internal pressure Pt is out of the predetermined pressure range (first pressure range). However, when the relief valve 30 is opened. However, the purge flow cannot be accurately detected due to the influence of the pressure fluctuation in the gas passage. For this reason, the fuel storage device according to the present embodiment detects the purge flow by the operation described below while the vehicle is traveling.

  FIG. 2 is a flowchart for explaining a series of operations for detecting a purge flow executed by the ECU 60 in the present embodiment. In the routine shown in FIG. 2, it is first determined whether or not a purge flow is currently being detected (step 100). If the purge flow is not currently being detected, the routine proceeds to step 114, where it is determined whether or not a predetermined basic condition for detecting the purge flow is satisfied. The purge flow detection basic conditions here are conditions other than steps 102 and 104 to be described later. For example, whether or not purge is being executed, that is, the switching valve 80 is turned OFF and the purge valve 36 is driven by duty. Whether or not there is included.

If the purge flow is currently being detected or if the purge flow detection basic condition is satisfied, it is next determined whether or not the condition of step 102 is satisfied. In step 102, it is determined whether or not the tank internal pressure Pt of the fuel tank 10 detected by the tank internal pressure sensor 12 is within a predetermined pressure range, that is, a range (second pressure range) that is larger than the lower limit pressure P _{L and} smaller than the upper limit pressure P _H. Determined. The determination condition of step 102 is a condition for detecting the purge flow in a pressure range in which the relief valve 30 does not open suddenly. For this reason, the lower limit pressure P _L is set to a value equal to or higher than the reverse valve opening pressure of the relief valve 30, and the upper limit pressure P _H is set to a value equal to or lower than the forward valve opening pressure of the relief valve 30.

As a result of the determination in step 102, when the tank internal pressure Pt becomes lower than the lower limit pressure P _L or higher than the upper limit pressure P _H , the detection of the purge flow is prohibited (step 110), and the block valve 28 is operated. The internal pressure control of the fuel tank 10 during traveling is permitted (step 112). As a result, if the purge flow is already detected, the detection is immediately stopped, and the detection is not executed even if the purge flow detection basic condition is satisfied. In a series of processing of steps 102, 110, and 112, the fuel tank 10 is caused by the action of excessive positive pressure or negative pressure by opening the closing valve 28 before the tank internal pressure Pt reaches the valve opening pressure of the relief valve 30. Reducing stress. At this time, the pressure in the gas passage fluctuates with the operation of the block valve 28, but the detection of the purge flow is prohibited because the detection of the purge flow is prohibited. it can.

On the other hand, if the result of determination in step 102 is that the tank internal pressure Pt is in a range greater than the lower limit pressure P _{L and} less than the upper limit pressure P _H, it is further determined whether or not the condition of step 104 is satisfied. The determination condition in step 104 is a condition for detecting the purge flow in a state where the closing valve 28 is reliably closed. In step 104, after the closing valve 38 is actuated, that is, the closing valve 38 is closed. It is determined whether or not a predetermined time (for example, 2 seconds) has elapsed. In the present embodiment, the operating status of the block valve 28 is indirectly determined from the output status of the opening command and the closing command from the ECU 60 to the blocking valve 28. The predetermined time is the closing time from the ECU 60. It is set in consideration of the responsiveness of the blocking valve 28 to the command.

  If the result of determination in step 104 is that a predetermined time has not elapsed since the closing valve 38 was activated, detection of the purge flow is prohibited (step 110). Although not shown in the routine of FIG. 2, of course, the detection of the purge flow is prohibited even during the operation of the blocking valve 28. This prohibits detection of the purge flow not only during the operation of the block valve 38 but also in a situation where the block valve 28 may not be securely closed. Can be prevented. Note that “prohibit detection of purge flow” here means that the routine for detecting the purge flow is stopped, the routine for detecting the purge flow is executed, but the detection obtained For example, control using data is not performed. While detection of the purge flow is prohibited, the internal pressure control of the fuel tank 10 during traveling by operating the block valve 28 is permitted (step 112).

  On the other hand, if the result of determination in step 104 is that a predetermined time has elapsed after the closing valve 38 is operated, the internal pressure control of the fuel tank 10 during traveling by operating the closing valve 28 is prohibited (step 106). Subsequently, detection of the purge flow is permitted (step 108). If the purge flow is already detected, the determination condition in step 104 is always satisfied, but in this case, the operation of the block valve 28 during the purge flow detection is prohibited. Accordingly, the purge flow is not affected by the pressure fluctuation in the gas passage due to the sudden opening of the relief valve 30 and without being affected by the pressure fluctuation in the gas passage due to the operation of the block valve 28. Can be accurately detected.

  In the embodiment described above, the “detection prohibiting means” according to the first aspect of the present invention is realized by the execution of the processing of steps 104 and 110 by the ECU 60. Further, the “detection prohibiting means” according to the second aspect of the present invention is realized by the execution of the processing of steps 102 and 110 by the ECU 60. Further, the “operation prohibiting means” according to the third aspect of the present invention is realized by the execution of the processing of steps 100 and 106 by the ECU 60. Further, the “operation prohibition canceling means” of the fourth aspect of the invention is realized by the execution of the processes of steps 102 and 112 by the ECU 60, and the “detection prohibiting means” is realized by the execution of the process of step 110.

Others.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above embodiment, the pressure in the pump passage 78 in the negative pressure pump module 52 is detected to detect the purge flow. However, if the pressure effect accompanying the purge can be detected, the atmospheric passage 54 to the purge passage is used. The pressure at any location in the gas passage leading to 34 may be detected. Further, the purge flow detection method is not limited to the method of the above embodiment as long as it is detected based on at least the pressure in the gas passage.

  In the above-described embodiment, the predetermined time required for the determination in step 104 is set in consideration of the responsiveness of the closing valve 28 to the closing command from the ECU 60. When there is a waiting time until the pressure pulsation is settled, the above predetermined time may be set in consideration of the waiting time. According to this, since the detection of the purge flow in the situation where the pressure pulsation remains in the gas passage is prohibited, the purge flow is not affected by the pressure pulsation in the gas passage remaining after the closing valve 28 is operated. It becomes possible to detect the flow accurately.

  In the above embodiment, the operation of the blocking valve 36 is indirectly determined from the output of the command signal from the ECU 60. However, a sensor that detects the operation of the blocking valve 36 is provided and is determined based on the detection signal of the sensor. It may be. Alternatively, the blocking valve 38 may be indirectly determined from the change in the tank internal pressure Pt of the fuel tank 10. For example, it can be inferred that the closing valve 38 is operating while the tank internal pressure Pt changes greatly.

It is a figure for demonstrating the structure of the evaporative fuel processing apparatus of embodiment of this invention. It is a figure for demonstrating the detailed structure of the negative pressure pump module shown in FIG. 1 (A). It is a flowchart of the purge flow detection routine performed in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel tank 12 Tank internal pressure sensor 20 Vapor passage 28 Sealing valve 30 Relief valve 26 Canister 34 Purge passage 36 Purge valve 38 Intake passage 52 Negative pressure pump module 54 Atmospheric passage 56 Air filter 86 Pump module pressure sensor 60 ECU (Electronic Control Unit)
Pt tank internal pressure

Claims (4)

An evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to an intake passage of the internal combustion engine, and a gas passage in which the canister is disposed midway,
A sealing valve disposed between the fuel tank and the canister;
Tank internal pressure control means for operating the block valve to control the pressure in the fuel tank;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
Detection prohibiting means for prohibiting detection of the purge flow by the purge flow detecting means during operation of the blocking valve, or until the predetermined time elapses during operation of the blocking valve and after operation;
An evaporative fuel processing apparatus for an internal combustion engine, comprising: An evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to an intake passage of the internal combustion engine, and a gas passage in which the canister is disposed midway,
A relief valve disposed between the fuel tank and the canister and opened when a pressure in the fuel tank is out of a predetermined first pressure range;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
Detection prohibiting means for prohibiting detection of a purge flow by the purge flow detection means when the pressure in the fuel tank is outside a predetermined second pressure range included in the first pressure range;
An evaporative fuel processing apparatus for an internal combustion engine, comprising: An evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
One end is open to the atmosphere, the other end is connected to the intake passage of the internal combustion engine, and a gas passage in which the canister is disposed,
A sealing valve disposed between the fuel tank and the canister;
Tank internal pressure control means for operating the block valve to control the pressure in the fuel tank;
Purge flow detection means for detecting a purge flow based on the pressure in the gas passage;
An operation prohibiting means for prohibiting the operation of the block valve by the tank internal pressure control means during detection of the purge flow by the purge flow detection means;
An evaporative fuel processing apparatus for an internal combustion engine, comprising: An operation prohibition releasing means for canceling the prohibition of the operation of the blocking valve by the operation prohibiting means when the pressure in the fuel tank is out of a predetermined pressure range;
Detection prohibiting means for prohibiting detection of purge flow by the purge flow detecting means when releasing the prohibition of operation of the blocking valve;
The fuel vapor processing apparatus for an internal combustion engine according to claim 3, further comprising:

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