JP2014190310A - Evaporated fuel processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporated fuel processing apparatus capable of further appropriately decreasing the pressure in a fuel tank than conventional ones.SOLUTION: An ECU calculates a differential pressure dP by subtracting a canister internal pressure from a tank internal pressure (step S2). When a determination is made that a purge operation is being performed by a purge mechanism (step S3), the ECU determines whether the differential pressure dP is lower than a pressure difference Pb (step S4). When a determination is made that the differential pressure dP is not lower than the pressure difference Pb, the ECU inhibits execution of depressurization processing (step S6).

Description

  The present invention relates to a fuel vapor processing apparatus.

  As a conventional evaporative fuel processing apparatus, a canister capable of adsorbing evaporative fuel generated in a fuel tank storing fuel of an internal combustion engine, an evaporative fuel passage communicating the fuel tank and the canister, an evaporative fuel passage, A sealing valve that is an electromagnetic valve capable of opening and closing the fuel passage, a specific means for specifying the pressure in the fuel tank, and if the pressure in the fuel tank is equal to or higher than a predetermined reference pressure, the pressure in the fuel tank is predetermined. At least a specific means so that the inflow amount of the evaporated fuel flowing from the fuel tank to the canister per unit time does not exceed the instantaneous adsorbable amount that can be adsorbed per unit time of the canister. There is known one provided with a closing valve control means for controlling the opening and closing of the closing valve based on the pressure specified by (see, for example, Patent Document 1).

JP 2010-281258 A

  However, in the conventional fuel vapor processing apparatus, when the purge operation is performed when the pressure in the fuel tank is high and the block valve is opened, the full tank detection float valve (Onboard refueling vapor recovery) provided in the fuel tank is opened. valve (hereinafter referred to as “ORVR valve”), the valve element is pressed against the valve seat by the pressure difference between the fuel tank and the canister (hereinafter also referred to as “adsorber”), and the pressure in the fuel tank is reduced. There was a problem that it could not be properly reduced.

  Therefore, an object of the present invention is to provide an evaporative fuel processing apparatus capable of appropriately reducing the pressure in the fuel tank as compared with the conventional one.

  In order to achieve the above object, an evaporative fuel processing apparatus of the present invention includes: (1) a fuel tank for storing fuel of an internal combustion engine, an adsorber for adsorbing evaporative fuel generated in the fuel tank, and the adsorber. A purge mechanism that performs a purge operation for sucking evaporated fuel into the intake pipe of the internal combustion engine, and a communication path that connects the inside of the fuel tank and the inside of the adsorber via an ORVR valve provided in the fuel tank. In the evaporative fuel processing apparatus, comprising: a sealing valve for sealing; and a pressure relief processing unit for performing a pressure relief process for reducing the pressure in the fuel tank by opening and closing the valve, the pressure relief processing unit On the condition that the difference between the pressure in the fuel tank and the pressure in the adsorber is equal to or greater than a predetermined pressure difference in a state where the purge operation is being performed. It has a configuration that prohibits execution.

  With this configuration, the fuel vapor processing apparatus according to the present invention is provided on the condition that the difference between the pressure in the fuel tank and the pressure in the adsorber is equal to or greater than a predetermined pressure difference in a state where the purge operation is being performed. By prohibiting the execution of the depressurization process, the pressure in the fuel tank can be appropriately reduced as compared with the conventional one in order to prevent the ORVR valve body from being pressed against the valve seat. .

  In the evaporated fuel processing apparatus according to the above (1), (2) the depressurization processing unit is configured such that the difference between the pressure in the fuel tank and the pressure in the adsorber is equal to or greater than a predetermined pressure difference. On the condition that the execution of the depressurization process is prohibited, the execution of the purge operation may be prohibited and the depressurization process may be executed.

  With this configuration, the evaporative fuel processing apparatus of the present invention inhibits the ORVR valve body from being pressed against the valve seat by the purge operation by prohibiting the start of the purge operation. The pressure in the fuel tank can be appropriately reduced as compared with the above.

  ADVANTAGE OF THE INVENTION According to this invention, the evaporative fuel processing apparatus which can reduce the pressure in a fuel tank appropriately can be provided compared with the conventional one.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a main part including an internal combustion engine for driving in a vehicle equipped with an evaporative fuel processing apparatus according to an embodiment of the present invention and a fuel system thereof. It is a conceptual diagram for demonstrating the structure of the ORVR valve | bulb shown in FIG. It is a flowchart which shows the pressure release operation | movement performed by the evaporative fuel processing apparatus which concerns on embodiment of this invention.

  Embodiments of an evaporated fuel processing apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows a main configuration of a vehicle equipped with an evaporative fuel processing apparatus according to an embodiment of the present invention, that is, a mechanism of an internal combustion engine for driving and a fuel system for supplying and purging the fuel. ing. The internal combustion engine of the present embodiment uses highly volatile fuel and is mounted on a vehicle for driving driving.

  First, the configuration will be described.

  As shown in FIG. 1, a vehicle 1 according to the present embodiment includes an engine 2 as an internal combustion engine, a fuel supply mechanism 3, a fuel purge system 4 and an ECU (Electronic Control Unit) 5 that constitute an evaporative fuel processing device. It is comprised including.

  The engine 2 is constituted by a spark ignition type multi-cylinder internal combustion engine using a spark plug 20 controlled by the ECU 5, for example, a four-cycle in-line four-cylinder engine in the present embodiment.

  Each of the intake ports of the four cylinders 2a (only one is shown in FIG. 1) of the engine 2 is provided with an injector 21 (fuel injection valve), and the plurality of injectors 21 are connected to a delivery pipe 22. Has been.

  A highly volatile fuel, for example, gasoline, is pressurized and supplied to the delivery pipe 22 to a fuel pressure (fuel pressure) required for the engine 2 from a fuel pump 32 described later.

  An intake pipe 23 is connected to the intake port portion of the engine 2, and the intake pipe 23 is provided with a surge tank 23 a having a predetermined volume that suppresses intake pulsation and intake interference.

  An intake passage 23b is formed inside the intake pipe 23, and a throttle valve 24 that is driven by a throttle actuator 24a so that the opening degree can be adjusted is provided on the intake passage 23b.

  The throttle valve 24 adjusts the intake air amount of the engine 2 by adjusting the opening of the intake passage 23 b under the control of the ECU 5. The throttle valve 24 is provided with a throttle sensor 24b for detecting the opening degree.

  The fuel supply mechanism 3 includes a fuel tank 31 that stores the fuel of the engine 2, a fuel pump 32 that pumps up the fuel stored in the fuel tank 31, a fuel supply pipe 33 that connects the fuel pump 32 and the delivery pipe 22, and a fuel And a suction pipe 38 provided on the upstream side of the pump 32.

  The fuel tank 31 is disposed on the lower side of the vehicle body of the vehicle 1 and stores fuel consumed by the engine 2 in a replenishable manner. In the present embodiment, the fuel pump 32 is accommodated in the fuel tank 31.

  The fuel pump 32 is of a variable discharge capability (discharge amount and discharge pressure) type that can pump up the fuel in the fuel tank 31 and pressurize it to a predetermined feed fuel pressure or more, and is constituted by a circumferential flow pump, for example. . The fuel pump 32 has an impeller for operating the pump and a built-in motor that drives the impeller, although a detailed internal configuration is not shown.

  Further, the fuel pump 32 changes its discharge capacity per unit time by changing at least one of the rotational speed and rotational torque of the impeller for operating the pump according to the drive voltage and load torque of the built-in motor. It can be made to.

  In order to change the discharge capacity of the fuel pump 32 in this way, the fuel supply mechanism 3 is provided with an FPC (Fuel Pump Controller) 84 that controls the drive voltage of the fuel pump 32 in accordance with the control of the ECU 5.

  The fuel supply pipe 33 forms a fuel supply passage that allows the output port of the fuel pump 32 and the inside of the delivery pipe 22 to communicate with each other. The suction pipe 38 forms a suction passage 38a on the upstream side of the fuel pump 32, and a suction filter 38b is provided at the most upstream portion of the suction passage 38a. The suction filter 38b is a known filter that filters the fuel sucked into the fuel pump 32.

  On the other hand, the fuel tank 31 is provided with a fuel supply pipe 34 so as to extend from the fuel tank 31 to the side or the rear side of the vehicle 1. An oil supply port 34 a is formed at the tip of the oil supply pipe 34 in the protruding direction. The fuel filler 34 a is accommodated in a fuel inlet box 35 provided in a body (not shown) of the vehicle 1.

  The fuel supply pipe 34 is provided with a circulation pipe 36 that communicates the upper part of the fuel tank 31 with the upstream portion in the fuel supply pipe 34. The fuel inlet box 35 is provided with a fuel lid 37 that is opened to the outside when fuel is supplied.

  When fuel is supplied, the fuel lid 37 is opened, and the cap 34b detachably attached to the fuel supply port 34a is removed, so that the fuel can be injected into the fuel tank 31 from the fuel supply port 34a.

  The fuel purge system 4 is interposed between the fuel tank 31 and the intake pipe 23, more specifically, between the fuel tank 31 and the surge tank 23a. The fuel purge system 4 is configured such that the evaporated fuel generated in the fuel tank 31 can be discharged into the intake passage 23b and combusted during intake of the engine 2.

  The fuel purge system 4 includes a canister 41 that constitutes an adsorber that adsorbs the evaporated fuel generated in the fuel tank 31, and purge gas containing air and fuel that has been desorbed from the canister 41 through the canister 41. 23 includes a purge mechanism 42 that performs a purge operation to be sucked into the engine 23, and a purge control mechanism 45 that controls the amount of purge gas sucked into the intake pipe 23 to suppress fluctuations in the air-fuel ratio in the engine 2. Yes.

  The canister 41 includes an adsorbent 41b such as activated carbon inside a canister case 41a and is installed outside the fuel tank 31. The interior of the canister 41 (adsorbent storage space) communicates with an upper space in the fuel tank 31 via a vapor pipe 48 that forms a communication path between the fuel tank 31 and the canister 41.

  Therefore, the canister 41 can adsorb the evaporated fuel by the adsorbent 41 b when the fuel evaporates in the fuel tank 31 and the evaporated fuel accumulates in the upper space in the fuel tank 31.

  In the fuel tank 31, an ORVR valve 49 and a COV (Cut Off Valve) 50 are provided in the vapor pipe 48. The ORVR valve 49 includes a float valve 90 (valve element) having a specific gravity smaller than that of fuel, and a valve seat 93 against which the float valve 90 contacts when the ORVR valve 49 is closed.

  The ORVR valve 49 is closed when the liquid level rises during refueling, and the communication between the vapor pipe 48 and the fuel tank 31 is cut off. Further, the ORVR valve 49 blocks communication between the vapor pipe 48 and the fuel tank 31 even when the vehicle falls or the like, so that fuel in the fuel tank 31 does not leak to the outside via the vapor pipe 48. It has become.

  As shown in FIG. 2, the ORVR valve 49 is a sealing valve when the purge operation is being performed when the pressure in the fuel tank 31 is relatively low (for example, less than 15 kPa), as indicated by reference numeral 100. When the valve 52 is opened, the evaporated fuel in the fuel tank 31 is sucked through the ORVR valve 49 at a relatively low pressure.

  For this reason, the float valve 90 floats slightly in the ORVR valve 49, but since the float valve 90 does not hit the valve seat 93, the evaporated fuel is sucked into the canister 41 via the vapor pipe 48.

  On the other hand, when the pressure in the fuel tank 31 is relatively high (for example, 15 kPa or more), when the blocking valve 52 is opened while the purge operation is being performed, the evaporated fuel in the fuel tank 31 is Suction is performed at a relatively high pressure through the ORVR valve 49.

  In this case, as indicated by reference numeral 101, the float valve 90 floats in the ORVR valve 49 and hits the valve seat 93, so that the evaporated fuel is not sucked into the canister 41 via the vapor pipe 48, and the fuel tank The pressure in 31 cannot be lowered.

  For this reason, the float valve 90 is formed with a fine communication path 92 that allows the fuel tank 31 and the vapor pipe 48 to communicate with each other. Therefore, even if the float valve 90 is in contact with the valve seat 93, the fuel in the fuel tank 31 gradually decreases due to a small amount of evaporated fuel flowing through the communication path 92.

  As a result, a gap is formed between the float valve 90 and the valve seat 93 as indicated by reference numeral 102, and the evaporated fuel flows through this gap, so that the pressure in the fuel tank 31 and the ORVR valve 49 are blocked. The pressure difference from the valve 52 side decreases, the float valve 90 moves away from the valve seat 93, and the float valve 90 returns to the normal position in the ORVR valve 49.

  In FIG. 1, the COV 50 is arranged in parallel with the ORVR valve 49 so that the communication between the vapor pipe 48 and the fuel tank 31 is cut off when the liquid level rises further than the position of the ORVR valve 49. It has become.

  When the liquid level rises due to refueling, the COV 50 remains open even after the ORVR valve 49 is closed. However, the COV 50 is closed when the liquid level reaches the position of the COV 50 due to the fluctuation of the liquid level due to turning of the vehicle. The communication between the vapor pipe 48 and the fuel tank 31 is cut off, so that the fuel in the fuel tank 31 does not leak to the outside via the vapor pipe 48.

  The vapor pipe 48 includes a blocking valve unit 51 in the middle thereof. The block valve unit 51 includes a block valve 52 and a relief valve 53. The blocking valve 52 is configured by a normally closed electromagnetic valve that closes when not energized and opens when energized.

  Here, as the blocking valve 52, there is one constituted by a two-stage valve having a small diameter and a large diameter, but in the present embodiment, by opening to a large diameter at the time of refueling, more evaporation is performed. In order to adsorb the fuel to the canister 41, it is constituted by a single-stage valve having only a large diameter.

  The relief valve 53 includes a forward relief valve that opens when the pressure on the fuel tank 31 side is sufficiently higher than the pressure on the canister 41 side, and the pressure on the fuel tank 31 side becomes the pressure on the canister 41 side. It is constituted by a mechanical bidirectional check valve comprising a reverse relief valve that opens when the pressure is sufficiently low. For example, the valve opening pressure of the relief valve 53 is set to about 20 kPa in the forward direction and about 10 kPa in the reverse direction.

  The purge mechanism 42 includes a purge pipe 43 that communicates the inside of the canister 41 with the internal portion of the surge tank 23a in the intake passage 23b of the intake pipe 23, and the inside of the canister 41 on the atmosphere side, for example, the inside of the fuel inlet box 35. And an atmospheric pipe 44 opened to the atmospheric pressure space.

  When an intake negative pressure is generated inside the surge tank 23 a during operation of the engine 2, the purge mechanism 42 introduces the intake negative pressure through one end side of the canister 41 through the purge pipe 43, while the other inside the canister 41. The atmosphere can be introduced through the atmosphere piping 44 to the end side.

  In this way, the purge mechanism 42 can cause the fuel adsorbed by the adsorbent 41b of the canister 41 and held in the canister 41 to be desorbed from the canister 41 and sucked into the surge tank 23a.

  The purge control mechanism 45 includes a purge vacuum solenoid valve (hereinafter referred to as “purge VSV”) 46 controlled by the ECU 5. The purge VSV 46 is provided in the middle of the purge pipe 43. The purge VSV 46 can variably control the flow rate of the evaporated fuel desorbed from the canister 41 by changing the opening degree in the middle of the purge pipe 43.

  Specifically, the purge VSV 46 can change the opening degree by the duty of the excitation current being controlled by the ECU 5, and the purge VSV 46 can be changed by the intake negative pressure in the intake pipe 23 at a purge rate corresponding to the duty ratio. The evaporated fuel desorbed from the canister 41 can be sucked into the surge tank 23a as purge gas together with air.

  The ECU 5 includes a central processing unit (CPU) 70, a random access memory (RAM) 71, a read only memory (ROM) 72, a flash memory 73, and an input / output port (hereinafter referred to as “I / O port”) 74. It is comprised by the computer apparatus provided with these.

  The ROM 72 of the ECU 5 stores a program for causing the computer device to function as the ECU 5. That is, when the CPU 70 executes a program stored in the ROM 72 using the RAM 71 as a work area, the computer device functions as the ECU 5.

  On the input side of the I / O port 74, in addition to the throttle sensor 24 b, a tank internal pressure sensor 55 that detects the pressure in the fuel tank 31 (hereinafter simply referred to as “tank internal pressure”), and a pressure in the canister 41 (hereinafter referred to as “tank pressure”). Various sensors including a canister internal pressure sensor 56 that simply detects “canister internal pressure” are connected. In the present embodiment, the canister internal pressure sensor 56 is provided in the vicinity of the canister 41 of the atmospheric piping 44.

  Various control objects such as a spark plug 20, a throttle actuator 24a, a purge VSV 46, a blocking valve 52, and an FPC 84 are connected to the output side of the I / O port 74.

  The ECU 5 controls various control objects based on information detected by various sensors. For example, the ECU 5 can control the purge rate by duty-controlling the purge VSV 46 based on various sensor information.

  Specifically, when the engine 2 is in a predetermined operation state, the ECU 5 is provided on the condition that the opening degree of the throttle valve 24 obtained from the throttle sensor 24b is smaller than a preset opening degree. By operating the purge VSV 46, the purge mechanism 42 is caused to execute a purge operation.

  Further, in the present embodiment, the ECU 5 constitutes a pressure release processing unit that executes a pressure release process for reducing the pressure in the fuel tank 31 by opening and closing the sealing valve 52. The ECU 5 is configured to perform a pressure releasing operation on condition that the tank internal pressure detected by the tank internal pressure sensor 55 is higher than a predetermined specified pressure Pa. Here, the specified pressure Pa is experimentally determined in advance and stored in the ROM 72.

  The ECU 5 prohibits execution of the depressurization process on the condition that the difference between the pressure in the fuel tank 31 and the pressure in the canister 41 is equal to or greater than a predetermined pressure difference Pb while the purge operation is being performed. It is supposed to be. Here, the pressure difference Pb is experimentally determined in advance and stored in the ROM 72.

  Specifically, the ECU 5 has a differential pressure obtained by subtracting the canister internal pressure detected by the canister internal pressure sensor 56 from the tank internal pressure detected by the purge operation tank internal pressure sensor 55 while the purge mechanism 42 is performing the purge operation. On the condition that dP is equal to or greater than the pressure difference Pb, the execution of the depressurization process is prohibited, and the in-tank high pressure flag stored in the RAM 71 or the like is set to ON.

  Further, the ECU 5 performs the pressure release process on the condition that the differential pressure dP obtained by subtracting the canister internal pressure from the tank internal pressure is less than the pressure difference Pb while the purge mechanism 42 is performing the purge operation. It has become.

  Further, the ECU 5 starts executing the purge operation on condition that the execution of the depressurization process is prohibited because the difference between the pressure in the fuel tank 31 and the pressure in the canister 41 is equal to or greater than the pressure difference Pb. This is prohibited and the pressure release process is executed.

  Specifically, the ECU 5 prohibits execution of the purge operation by the purge mechanism 42 on the condition that the high pressure flag in the tank is on in a state where the purge mechanism 42 is not performing the purge operation, and performs the pressure relief process. Is supposed to run.

  When the ECU 5 determines that the end condition of the pressure release process is satisfied after executing the pressure release process in a state where the purge mechanism 42 is not performing the purge operation, the ECU 5 ends the pressure release process and the high pressure in the tank. The flag is set to OFF, and the purge mechanism 42 is allowed to execute the purge operation.

  In the present embodiment, the end condition of the depressurization process is satisfied when the differential pressure dP obtained by subtracting the canister internal pressure from the tank internal pressure is less than a predetermined pressure difference Pc for a predetermined time. . Here, the pressure difference Pc is lower than the pressure difference Pb, is experimentally determined in advance, and is stored in the ROM 72.

  Further, the ECU 5 prohibits the execution of the pressure relief process on the condition that the in-tank high-pressure flag is off while the purge mechanism 42 is not performing the purge operation.

  Next, the pressure releasing operation of the evaporated fuel processing apparatus according to the present embodiment will be described with reference to the flowchart shown in FIG. Note that the pressure release operation described below is repeatedly executed by the ECU 5 in parallel with the purge operation.

  First, the ECU 5 determines whether or not the tank internal pressure is higher than the specified pressure Pa (step S1). Here, when it is determined that the tank internal pressure is not higher than the specified pressure Pa, the ECU 5 ends the pressure releasing operation.

  On the other hand, when determining that the tank internal pressure is higher than the specified pressure Pa, the ECU 5 calculates a differential pressure dP obtained by subtracting the canister internal pressure from the tank internal pressure (step S2). Next, the ECU 5 determines whether or not the purge mechanism 42 is performing a purge operation (step S3).

  Here, if it is determined that the purge mechanism 42 is performing the purge operation, the ECU 5 determines whether or not the differential pressure dP is less than the pressure difference Pb (step S4). If it is determined that the differential pressure dP is less than the pressure difference Pb, the ECU 5 executes a pressure relief process (step S5).

  On the other hand, when determining that the differential pressure dP is not less than the pressure difference Pb, the ECU 5 prohibits the execution of the pressure release process (step S6), sets the tank high pressure flag to ON (step S7), and releases the pressure. End the operation.

  If it is determined in step S3 that the purge mechanism 42 is performing the purge operation, the ECU 5 determines whether or not the in-tank high pressure flag is on (step S8).

  If it is determined that the high pressure flag in the tank is not ON, the ECU 5 prohibits execution of the pressure release process (step S9) and ends the pressure release operation. On the other hand, when it is determined that the tank high-pressure flag is on, the ECU 5 prohibits execution of the purge operation (step S10) and executes a pressure relief process (step S11).

  Next, the ECU 5 determines whether or not the termination condition for the pressure relief process is satisfied (step S12). Here, if it is determined that the end condition of the pressure release process is not satisfied, the ECU 5 ends the pressure release operation.

  On the other hand, if it is determined that the termination condition for the pressure release process is not satisfied, the ECU 5 sets the tank high pressure flag to OFF (step S13), permits the execution of the purge operation (step S14), and releases the pressure. End the operation.

  As described above, the present embodiment is based on the condition that the difference dP between the pressure in the fuel tank 31 and the pressure in the canister 41 is equal to or greater than the pressure difference Pb in a state where the purge operation is being performed. By prohibiting the execution of the pressure release process, the pressure in the fuel tank 31 is appropriately reduced as compared with the conventional one in order to suppress the float valve 90 of the ORVR valve 49 from being pressed against the valve seat 93. be able to.

  Further, in the present embodiment, the purge operation is executed on condition that the pressure release process is prohibited because the difference dP between the pressure in the fuel tank 31 and the pressure in the canister 41 is equal to or larger than the pressure difference Pb. Is prohibited from being started, and the pressure relief process is executed.

  For this reason, this embodiment suppresses the float valve 90 of the ORVR valve 49 from being pressed against the valve seat 93 by the purge operation by prohibiting the start of the purge operation. As compared with the above, the pressure in the fuel tank 31 can be appropriately reduced.

  In the present embodiment, the fuel pump 32 is described as being housed inside the fuel tank 31. However, in the present invention, the fuel pump 32 may be provided outside the fuel tank 31. .

  In the present embodiment, the canister 41 is described as being provided outside the fuel tank 31. However, in the present invention, the canister 41 may be accommodated inside the fuel tank 31.

  As described above, the evaporative fuel processing device according to the present invention has an effect that the pressure in the fuel tank can be appropriately reduced as compared with the conventional one, and is particularly applicable to an internal combustion engine. It is useful for an evaporative fuel processing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Engine (internal combustion engine), 5 ... ECU (pressure release process part), 31 ... Fuel tank, 41 ... Canister (adsorber), 42 ... Purge mechanism, 49 ... ORVR valve, 52 ... Sealing valve

Claims (2)

A fuel tank for storing fuel of the internal combustion engine;
An adsorber for adsorbing the evaporated fuel generated in the fuel tank;
A purge mechanism for performing a purge operation for sucking evaporated fuel from the adsorber into the intake pipe of the internal combustion engine;
A blocking valve that blocks a communication path that connects the inside of the fuel tank and the inside of the adsorber via an ORVR valve provided in the fuel tank;
An evaporative fuel processing apparatus comprising: a depressurization processing unit that performs a depressurization process for reducing the pressure in the fuel tank by opening and closing the sealing valve;
The depressurization processing unit is conditioned on the condition that the difference between the pressure in the fuel tank and the pressure in the adsorber is equal to or greater than a predetermined pressure difference in a state where the purge operation is being performed. An evaporative fuel processing apparatus that prohibits execution of a removal process.   The depressurization processing unit performs the purge operation on the condition that execution of the depressurization process is prohibited because a difference between the pressure in the fuel tank and the pressure in the adsorber is equal to or greater than the pressure difference. The evaporative fuel processing apparatus according to claim 1, wherein execution is prohibited and the pressure release process is executed.

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