JPH08128362A - Failure diagnosing device of evaporated fuel processing device - Google Patents

Abstract

PURPOSE: To prevent the occurrence of erroneous diagnosis of leakage due to influence of residual pressure of a purge system by supplying adsorbed and collected evaporated fuel to an intake air passage by discharging it when an engine is operated, and removing the residual pressure by opening the purge system prior to pressure reducing processing to diagnose leakage failure. CONSTITUTION: When failure is diagnosed by an ECU 50, first of all, in order to remove residual pressure, a drain cut valve 43 is opened, and in succession, the drain cut valve 43 is closed, and tank internal pressure is measured, and whether or not the tank internal pressure is reduced more than reference pressure is judged. Here, in the case of Yes, when a failure diagnosing practicing condition is realized, the drain cut valve 43 is closed, and in order to reduce pressure from inside of a tank, a purge valve 41 is opened for a constant time. The tank internal pressure is measured by a pressure sensor 45, and whether or not the tank internal pressure is reduced up to prescribed pressure is judged, and when pressure reduction is not completed for a constant time, it is judged as failure causing large leakage in a purge system, and an alarm lamp 54 is lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporated fuel which adsorbs and collects evaporated fuel generated in a fuel tank or the like and discharges the adsorbed and collected evaporated fuel during engine operation and supplies it to an intake passage. The present invention relates to a failure diagnosis device that performs a leakage diagnosis of a processing device.

[0002]

2. Description of the Related Art In engines of automobiles and the like, conventionally, evaporated fuel generated in a fuel tank or the like is adsorbed and collected by a canister containing activated carbon, and the adsorbed and collected fuel is purged (released) during engine operation. 2) is provided to the intake system. This evaporative fuel treatment apparatus is provided with a purge valve for adjusting the flow rate of purge gas (purge flow rate) in a purge passage that connects a canister and an intake passage of an engine, and controls the supply of evaporative fuel to an intake system by controlling the purge valve. Is normal.

Further, in such an evaporated fuel processing apparatus, it is necessary to monitor the leak of the purge system, and therefore, as described in, for example, Japanese Patent Laid-Open No. 4-362264, the atmosphere of the canister is changed. An open / close valve is provided at the opening, and when a predetermined diagnostic execution condition is satisfied, the open / close valve is closed, and the purge valve is opened to introduce the intake negative pressure to the purge system, and then only the purge valve is closed to close the purge system. 2. Description of the Related Art Conventionally, a failure diagnosis device has been proposed which diagnoses a failure of a purge system based on a change in internal pressure.

[0004]

SUMMARY OF THE INVENTION In the above-mentioned conventional failure diagnosis apparatus for an evaporated fuel processing apparatus, the on-off valve provided at the atmosphere opening port of the canister is closed, the purge valve is opened to reduce the pressure of the purge system, and then the purge valve is closed to perform the purge. The system is blocked, and the pressure of the purge system when the system is blocked and the pressure when a certain period of time has elapsed are checked. When the pressure rises above a predetermined value, it is determined that there is a leak in the purge system. Also, after the engine is started and warmed up, the temperature inside the fuel tank becomes higher than the outside air temperature, so if you close the purge system, the internal pressure will rise even if there is no leak, and therefore the leak will occur even though it is not a leak. An erroneous diagnosis such as the above determination occurs. Therefore, the above-mentioned failure diagnosis is usually performed immediately after starting. However, even immediately after the start-up, in a state where the pressure in the fuel tank rises due to a high outside temperature, the internal pressure of the purge system does not fall sufficiently even if the intake negative pressure is applied, or the purge system The internal pressure may rise when the valve is blocked, regardless of the leak, resulting in a false diagnosis.

An object of the present invention is to solve such a problem, and it is an object of the present invention to provide a failure diagnosing apparatus capable of accurately diagnosing a leak state of a purge system in an evaporated fuel processing apparatus. .

[0006]

According to the present invention, a vapor inlet and a purge outlet are provided so as to face an atmosphere opening port so that the vaporized fuel introduced from the vapor inlet can be adsorbed and collected, and the adsorbed vaporized fuel is released. A possible adsorption collection means, a vapor passage connecting the upper space of the fuel tank to the vapor inlet of the adsorption collection means, and a purge passage connecting the purge outlet of the adsorption collection means to the intake passage of the engine,
An opening / closing means that is provided in the purge passage and that adjusts a flow rate of the purge gas that is supplied to the intake passage through the purge passage, and that opens and closes the atmosphere opening port; The pressure detecting means for detecting the internal pressure of the purge system from the adjusting means to the fuel tank, and the opening / closing means are closed and the purge adjusting means is opened when a predetermined failure diagnosis execution condition is satisfied. A pressure reducing process executing means for lowering the internal pressure of the purge system by applying an intake negative pressure to the system, and the purge adjusting means is closed to close the purge system after the pressure reducing process by the pressure reducing process executing means is completed. The purging after completion of the processing by the blocking processing execution means, which receives the output of the blocking processing execution means and the pressure detection means. And a leak determining means for determining a leak state of the purge system based on a change in internal pressure of the purge system, wherein the purge system prior to the fault diagnosis has the structure of claim 1. The leak pressure is released to prevent a leak erroneous diagnosis due to the effect of the residual pressure, and the purge system is opened prior to the execution of the pressure reducing processing by the pressure reducing processing executing means. It is characterized in that a residual pressure removal executing means for removing the residual pressure inside the purge system is provided.

Further, according to the second aspect of the present invention, when the internal pressure of the purge system is high, malfunction diagnosis is prevented so as to prevent erroneous diagnosis. The pressure detection means receives the output of the pressure detection means. Provided is a diagnosis prohibiting means for prohibiting the failure diagnosis by stopping at least the leak state judging processing by the leak judging means when the internal pressure of the purge system is equal to or higher than a predetermined value immediately before the depressurizing process by the executing means is started. It is characterized by that.

According to the third aspect of the present invention, the residual pressure of the purge system is released prior to the failure diagnosis, so that the residual pressure of the purge system is not due to the continuous erroneous diagnosis factors such as the outside temperature but only due to the residual pressure. When the pressure is high, the failure diagnosis can be promptly executed. Prior to the execution of the depressurization process by the depressurization process execution means, the purge system is opened to release the residual pressure inside the purge system. When the internal pressure of the purge system is equal to or higher than a predetermined value immediately before the depressurization process is started by the depressurization process execution unit and the output of the removal execution unit and the pressure detection unit, at least the leak state determination by the leak determination unit is performed. It is characterized in that a diagnosis prohibiting means for prohibiting the failure diagnosis by stopping the processing of is provided.

Here, the failure diagnosis is preferably performed immediately after the engine is started. Therefore, in the structure of claim 4, the failure diagnosis processing by the decompression processing execution means, the sealing processing execution means, and the leak determination means is started by the engine. I decided to do it immediately.

Further, the residual pressure can be released by the opening / closing means. Therefore, in the configuration of claim 5, the residual pressure removing means is operated by opening the opening / closing means prior to the execution of the depressurizing process. The residual pressure inside the purge system was released by opening the atmosphere opening port.

Further, in the structure of claim 6, a drain cut valve is used as the opening / closing means.

Further, in the configuration of claim 7, in order to prevent the failure diagnosis from being performed when the internal pressure of the purge system is high,
The diagnosis prohibiting means prohibits the depressurization processing by the depressurization processing executing means when the internal pressure of the purge system immediately before the depressurization processing by the depressurization processing executing means is started is equal to or higher than a predetermined value.

FIG. 1 is an overall configuration diagram showing the above configuration of the present invention.

[0014]

The evaporated fuel generated in the fuel tank of the engine is adsorbed and collected by adsorbing and collecting means through the vapor passage.
When the purge adjusting means is opened, it is purged and supplied to the intake passage through the purge passage. At this time, the purge adjusting means controls the purge flow rate according to the operating state of the engine.

Further, when a predetermined failure diagnosis execution condition is satisfied, the opening / closing means provided in the atmospheric air release opening of the adsorption / collection means is closed and the purge adjusting means is opened. At this time, the intake negative pressure of the engine acts on the inside of the fuel tank, thereby reducing the pressure of the purge system. Then, the purge system is closed by closing the purge adjusting means in the depressurized state, and the leak state is determined based on the change in the internal pressure of the purge system in the closed state.

According to the first aspect of the invention, the purge system is opened and the residual pressure inside the purge system is released prior to the depressurization process in which the opening / closing means is closed and the purge adjusting means is opened.
As a result, insufficient reduction of pressure due to the effect of residual pressure is prevented, and erroneous leak diagnosis is prevented.

Further, according to the second aspect of the present invention, when the internal pressure of the purge system immediately before the depressurization process is started is equal to or higher than a predetermined value, at least the leak state determination process is stopped so that the failure diagnosis is prohibited. It As a result, failure diagnosis is prohibited and erroneous diagnosis is prevented when the pressure in the purge system cannot be sufficiently reduced or when the internal pressure in the purge system rises regardless of the leak.

According to the third aspect of the invention, the residual pressure inside the purge system is released by opening the purge system prior to the decompression process in which the opening / closing means is closed and the purge adjusting means is opened. When the internal pressure of the purge system immediately before the start is equal to or higher than a predetermined value, at least the leak state determination process is stopped to prohibit the failure diagnosis. As a result, the depressurization of the purge system is prevented from becoming insufficient due to the effect of the residual pressure, and it is possible to prevent the false misdiagnosis from occurring due to the effect of the temporary residual pressure, and to keep the outside temperature high. When the pressure in the purge system cannot be sufficiently reduced due to a certain factor or the internal pressure in the purge system rises irrespective of the leak, the failure diagnosis itself is prohibited, thereby preventing an erroneous diagnosis. Even if the internal pressure of the purge system at the start of diagnosis is high, if the internal pressure of the purge system is not due to a continuous factor such as the outside temperature but merely due to the effect of a temporary residual pressure, a leak failure is promptly detected. Can be run.

According to the fourth aspect of the present invention, the failure diagnosis is performed immediately after the engine is started when the pressure in the fuel tank is stable, thereby preventing erroneous leak detection.

According to the fifth aspect of the invention, the atmosphere opening port is opened prior to the execution of the depressurization process, whereby the residual pressure inside the purge system is released.

Further, according to the structure of claim 6, the drain cut valve is opened prior to the execution of the pressure reducing process, whereby the residual pressure inside the purge system is released.

According to the seventh aspect of the invention, when the internal pressure of the purge system immediately before the depressurization process is started is equal to or higher than the predetermined value, all the processes for failure diagnosis including the depressurization process are prohibited.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram of the first embodiment of the present invention. In the figure, 1 is an engine body. The engine body 1 has a cylinder block 2 forming a plurality of cylinders arranged in series, a piston 3 arranged in each cylinder, and a cylinder head 4 fixed to the upper part of the cylinder block 2,
In each cylinder of the cylinder block 2, a combustion chamber 5 is formed by being partitioned by the upper surface of the piston 3 and the lower surface of the cylinder head 4. The cylinder head 4 is provided with an intake port 6 and an exhaust port 7 that open to the combustion chamber 5 of each cylinder, and an intake valve 8 that opens and closes the intake port 6 and the exhaust port 7 at a predetermined timing. An exhaust valve 9 is provided. A cylinder head cover 10 is attached to the upper surface of the cylinder head 4, and an oil pan 11 is attached to the lower surface of the cylinder block.

The intake system of the engine includes an intake manifold 12 connected to the cylinder head 4, a throttle body 13 connected to the inlet side of the intake manifold 12,
Intake pipe 14 connected upstream of the throttle body 13
And an air flow meter 14 arranged at the tip thereof, and an air cleaner 1 connected upstream of the air flow meter 14.
It is composed of 5 and 5. And throttle body 1
3, a butterfly type throttle valve 16 is arranged. In addition, the intake manifold 12 is a surge tank 12
a, a primary passage 12b and a secondary passage 12c are branched and extended from the surge tank 12a for each cylinder, and the primary passage 12b and the secondary passage 12c are provided downstream of the surge tank 12a.
2d is connected to the cylinder head 4. The surge tank 1 is installed in the secondary passage 12c of each cylinder.
A secondary valve 18 that is opened / closed by an actuator 17 that operates according to the negative pressure in 2a is provided, and a fuel injection valve 19 is attached to each independent passage 12d near the cylinder head 4 side connection position.

Further, a bypass passage 20 that bypasses the throttle valve 13 is provided in the intake system of the engine, and a proportional passage for controlling the engine speed during idling by controlling the amount of bypass air in the bypass passage 20. An ISC valve (idle speed control valve) 21, which is an electromagnetic valve, is provided.

The exhaust system of the engine includes an exhaust manifold 22 connected to the cylinder head 4 at a position facing the intake manifold 12, and a catalytic converter 23 connected to the tip collecting portion of the exhaust manifold 22.
The exhaust pipe 24 is connected to the downstream side of the catalytic converter 23. Then, the exhaust system catalytic converter 2
O ₂ sensors 25 and 26 are respectively arranged on the upstream side and the downstream side of 3.

The fuel injection valve 19 in each independent passage 12d is connected to the fuel tank 29 by the fuel supply passage 27 and the fuel return passage 28. Also, the fuel tank 29
Has a built-in fuel pump 30, and the fuel supply passage 27 is connected to the discharge side of the fuel pump 30. Then, the low-pressure side fuel filter 3 is provided on the suction side of the fuel pump 30.
1 is disposed, and the fuel filter 32 on the high pressure side is disposed on the fuel supply passage 27 on the discharge side. A pressure regulator 33 for adjusting the fuel pressure is arranged in the fuel return passage 28. A boost pressure passage 34 that guides a reference pressure (boost pressure) from the surge tank 12a is connected to the pressure regulator 33.
4 is provided with a solenoid valve 35.

Further, the fuel system is provided with a device for processing evaporated fuel. That is, a canister (adsorption / collection means) 36 containing activated carbon is provided to burn the evaporated fuel generated in the fuel tank 29 in the combustion chamber 5. The canister 36 has an atmosphere opening port 36a at one end and a vapor inlet 36b and a purge outlet 36c at the other end facing the atmosphere opening port 36a. And
The upper space of the fuel tank 29 is connected to the vapor inlet 36b of the canister 36 by a vapor passage 37, and in the middle of the vapor passage 37, a separator 38 and a two-way valve for separating the liquid fuel from the evaporated fuel are sequentially provided from the fuel tank 29 side. 39 are provided. Also, canister 3
The purge outlet 36c of No. 6 is connected to the surge tank 12a of the intake manifold 12 by the purge passage 40. A purge valve 41, which is a duty solenoid valve, is disposed in the purge passage 40 as a purge adjusting means. Also, the canister 36
An atmosphere opening passage 42 is connected to the atmosphere opening port 36a of
A drain cut valve 43 and an air filter 44 are arranged in this order from the canister 36 side in the middle of the atmosphere opening passage 42. Further, the fuel system is provided with a pressure sensor 45 for detecting the pressure in the fuel tank 29.
An alcohol sensor 46 for detecting the alcohol concentration of the fuel inside is provided.

Further, the engine is provided with a rotation sensor 47 for detecting the rotation angle of the engine output shaft (crankshaft), and a water temperature sensor 4 for detecting the cooling water temperature of the engine.
8. A throttle sensor 49 for detecting the opening of the throttle valve 16 is provided.

An engine control unit 50 incorporating a microcomputer is attached to the engine. Then, the air flow meter 14, the O ₂ sensors 25 and 26, the pressure sensor 45, the alcohol sensor 46, the rotation sensor 47, the water temperature sensor 48, the throttle sensor 49.
Detection signals from various sensors are input. Further, the detection signal of the vehicle speed sensor 51 for detecting the vehicle speed, the surge tank 12a
The detection signal of the boost pressure sensor 52 that detects the boost pressure inside, the detection signal of the intake air temperature sensor 53 that detects the intake air temperature, etc. are input to the engine control unit 50. Then, based on these input signals, the engine control unit 50 causes the fuel injection valve 19, the ISC valve 2
1, the purge valve 41 and the like are controlled. Further, a MIL (warning lamp) 54 for warning of a purge failure is arranged in the vehicle compartment. And the engine control unit 5
The leak failure diagnosis processing of the evaporated fuel processing apparatus is performed by 0, and a lighting signal is output to the MIL 54 when a leak failure occurs.

In controlling the fuel injection valve 19, the rotation sensor 4
7, the basic injection amount is calculated based on the engine speed calculated from the output of 7 and the intake air amount detected by the air flow meter 8, and various corrections such as water temperature correction based on the output of the water temperature sensor 48 are added to the basic injection amount. Further, when the air-fuel ratio feedback control execution condition that the water temperature is, for example, 40 ° C. or more is satisfied in the predetermined feedback region of low and medium loads, the air-fuel ratio based on the deviation from the target air-fuel ratio of the output of the upstream O ₂ sensor 25 is satisfied. The fuel ratio feedback correction amount is calculated, and the correction based on the output of the downstream O ₂ sensor 26 is added to determine the final fuel injection amount, and the fuel injection is performed by the injection pulse corresponding to the fuel injection amount. The valve 19 is driven.

Further, in the control of the ISC valve 21, the bypass air amount is calculated based on the deviation between the actual engine speed and the target idle speed, and the ISC valve 21 is controlled so as to be the bypass air amount.

Further, in the control of the purge valve 41, the barge valve 41 according to the operating state of the engine is in the air-fuel ratio feedback region and when the predetermined purge execution condition is satisfied.
The control duty of is set by the map, and the purge valve 41 is controlled thereby.

The leak diagnosis of the purge system of the evaporated fuel processing apparatus, that is, the path from the purge valve 41 to the fuel tank 29 is performed as follows. That is, as shown in the time chart of FIG. 3, when the ignition signal (IG signal) is turned on (see) and a predetermined failure diagnosis execution condition is met and a flag is set (see), the drain is drained at that time. The cut valve 43 is closed (see) and the purge valve 41 is opened (see). Then, when the pressure in the fuel tank 29 decreases to a predetermined pressure, the purge valve 41
Closed, read the tank internal pressure (P ₁ ) at that time (see), operate the timer (see), and set the tank internal pressure (P ₂ ) at the time when the predetermined time set by the timer has elapsed. When reading (reference) and the pressure increase during that time is larger than the determination value, it is determined that a leak has occurred in the purge system, and the MIL 54 is turned on.

Further, in order to eliminate the influence of the residual pressure, the drain cut valve 43 is temporarily opened at the same time as the IG is turned on before the failure diagnosis (see FIG. 3). As a result, the residual pressure inside the purge system is released, and it is possible to prevent erroneous diagnosis of leak due to the influence of the residual pressure.

When there is a continuous erroneous diagnosis factor such as a high outside temperature, the tank pressure at the time when the residual pressure is released is read in order to prevent the leak diagnosis (see FIG. 3). The leak diagnosis is not performed when the pressure is above a predetermined value.

Hereinafter, the engine control unit 50
A signal processing procedure for fault diagnosis by means of will be described with reference to the flowchart of FIG. This flowchart is from S1 to S
It consists of 17 steps and starts when the ignition signal is ON. Then, first, in order to release the residual pressure, the drain cut valve (DCV) 43 is opened in step S1. Then, the drain cut valve 43 is closed in step S2, the tank internal pressure is measured in step S3, and it is determined in step S4 whether the tank internal pressure has become lower than the reference pressure.
And the steps S1 to S4 are repeated until the tank internal pressure becomes lower than the reference pressure. Here, the reference pressure is set to, for example, 10 to 20 mmHg.

When it is determined in step S4 that the tank pressure is lower than the reference pressure, the process proceeds to step S5,
Read the parameters for the fault diagnosis execution condition judgment. Parameters in this case are engine speed, boost pressure, vehicle speed, engine water temperature, intake air temperature, and the like. Then, in step S6, it is determined whether or not the failure diagnosis execution condition is satisfied. Here, for example, the engine speed is 1000 to
At 2000 rpm, boost pressure is -400 to -300 m
When the vehicle speed is 30 to 50 km / h, the engine water temperature is 20 to 30 ° C, and the intake air temperature is 20 to 30 ° C, it is determined that the failure diagnosis execution condition is satisfied. When it is determined that the failure diagnosis execution condition is satisfied, step S
7 proceeds, and if it is determined that the condition is not satisfied, step S
Return to 1.

When it is determined that the condition for executing the fault diagnosis is satisfied, the drain cut valve 43 is closed in step S7.
In order to reduce the pressure in the tank, the purge valve 41 is opened for a certain time in step S8. Then, in step S9, the tank internal pressure is measured, and in step S10, it is determined whether the tank internal pressure has dropped to a predetermined pressure (for example, about -20 mmHg).
That is, it is checked whether or not the predetermined decompression has been completed. If the pressure reduction is completed, the process proceeds to step S11. If decompression is not completed within a certain period of time,
Since there is a large leak in the purge system, it is determined as a failure in step S17, and the MIL 54 is turned on.

When the pressure reduction is completed, the purge valve 41 is closed in step S11, and the tank internal pressure (pressure 1) is measured in step S12. Further, in step S13, the tank internal pressure (pressure 2) after a predetermined time has elapsed is measured. The determination time in this case is set to be shorter as the alcohol concentration in the fuel is higher. That is, the higher the alcohol concentration in the fuel, the more easily the pressure in the fuel tank 29 rises. Therefore, the determination time is changed according to the alcohol concentration so that erroneous diagnosis does not occur. Then, in step S14, the pressure difference (pressure 2−pressure 1) during this period is calculated, and step S
In step 15, whether or not the pressure difference (pressure 2−pressure 1) is less than or equal to the judgment value is determined.

In the above embodiment, the drain cut valve 43 is used as the residual pressure releasing means (opening / closing means), but the residual pressure can be released by opening the purge valve 41. Is.

[0043]

According to the present invention, the purge system is opened and the residual pressure is released prior to the depressurization process for diagnosing the leak failure, thereby preventing the leak erroneous diagnosis from being caused by the residual pressure of the purge system. can do.

Further, according to the present invention, the failure diagnosis is prohibited when the internal pressure of the purge system is equal to or higher than a predetermined value, thereby preventing the internal pressure from rising and causing an erroneous diagnosis even if there is no leak failure. You can

Further, according to the present invention, the residual pressure of the purge system is released prior to the depressurization process, so that even if the internal pressure of the purge system is high, the cause is the temporary residual pressure and the outside air temperature or the like. If it is not continuous, the leak diagnosis can be executed promptly.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is a system diagram of an embodiment of the present invention.

FIG. 3 is a time chart schematically showing a failure diagnosis process according to an embodiment of the present invention.

FIG. 4 is a flowchart for executing a failure diagnosis process according to an embodiment of the present invention.

[Explanation of symbols]

 1 Engine Main Body 29 Fuel Tank 36 Canister (Adsorption and Collection Means) 36a Atmosphere Release Port 36b Vapor Inlet 36c Purge Outlet 37 Vapor Passage 40 Purge Passage 41 Purge Valve 50 Engine Control Unit

Claims (7)

[Claims] 1. An adsorption trapping means which is provided with a vapor inlet and a purge outlet facing the atmosphere opening port so as to adsorb and collect the vaporized fuel introduced from the vapor inlet and release the adsorbed vaporized fuel. A vapor passage connecting the upper space of the fuel tank to the vapor inlet of the adsorption collector, a purge passage connecting the purge outlet of the adsorption collector to the intake passage of the engine, and a purge passage interposed between the purge passage and the purge passage. A failure diagnosing device for an evaporated fuel processing apparatus, comprising: a purge adjusting unit that adjusts a flow rate of a purge gas supplied to the intake passage through a purge passage, the opening and closing unit opening and closing the atmosphere opening port. Pressure detecting means for detecting the internal pressure of the purge system from the purge adjusting means to the fuel tank, and closing operation of the opening / closing means when a predetermined failure diagnosis execution condition is satisfied. And the decompression processing executing means for lowering the internal pressure of the purging system by causing the purge adjusting means to open to act the intake negative pressure on the purging system, and after the decompression processing by the decompression processing executing means is completed. The internal pressure of the purge system after closing the purge adjusting means and closing the purge system, and receiving the output of the pressure detecting means and completing the process by the seal executing means. Leak determination means for determining the leak state of the purge system based on the change, and residual pressure removal for releasing the residual pressure inside the purge system to open the purge system prior to the execution of the pressure reduction processing by the pressure reduction processing execution means. A failure diagnosis apparatus for an evaporated fuel processing apparatus, characterized by comprising means. 2. An adsorbing and collecting means which is provided with a vapor inlet and a purge outlet facing the atmosphere opening port so as to adsorb and collect the vaporized fuel introduced from the vapor inlet and to release the adsorbed vaporized fuel. A vapor passage connecting the upper space of the fuel tank to the vapor inlet of the adsorption collector, a purge passage connecting the purge outlet of the adsorption collector to the intake passage of the engine, and a purge passage interposed between the purge passage and the purge passage. A failure diagnosing device for an evaporated fuel processing apparatus, comprising: a purge adjusting unit that adjusts a flow rate of a purge gas supplied to the intake passage through a purge passage, the opening and closing unit opening and closing the atmosphere opening port. Pressure detecting means for detecting the internal pressure of the purge system from the purge adjusting means to the fuel tank, and closing operation of the opening / closing means when a predetermined failure diagnosis execution condition is satisfied. And the decompression processing executing means for lowering the internal pressure of the purging system by causing the purge adjusting means to open to act the intake negative pressure on the purging system, and after the decompression processing by the decompression processing executing means is completed. The internal pressure of the purge system after closing the purge adjusting means and closing the purge system, and receiving the output of the pressure detecting means and completing the process by the seal executing means. The internal pressure of the purge system immediately before the depressurization process by the depressurization process execution unit is started by receiving the output of the leak determination unit that determines the leak state of the purge system based on the change and the output of the pressure detection unit. At the time of the above, at least a diagnosis prohibiting means for prohibiting the failure diagnosis by stopping the leak state judging process by the leak judging means is provided. Trouble diagnosis device for the fuel vapor processing apparatus characterized by a. 3. An adsorption trapping means which is provided with a vapor inlet and a purge outlet facing the atmosphere opening port so that the vaporized fuel introduced from the vapor inlet can be adsorbed and trapped and the adsorbed vaporized fuel can be released. A vapor passage connecting the upper space of the fuel tank to the vapor inlet of the adsorption collector, a purge passage connecting the purge outlet of the adsorption collector to the intake passage of the engine, and a purge passage interposed in the purge passage. A failure diagnosing device for an evaporated fuel processing apparatus, comprising: a purge adjusting unit that adjusts a flow rate of a purge gas supplied to the intake passage through a purge passage, the opening and closing unit opening and closing the atmosphere opening port. Pressure detecting means for detecting the internal pressure of the purge system from the purge adjusting means to the fuel tank, and closing operation of the opening / closing means when a predetermined failure diagnosis execution condition is satisfied. And the decompression processing executing means for lowering the internal pressure of the purging system by causing the purge adjusting means to open to act the intake negative pressure on the purging system, and after the decompression processing by the decompression processing executing means is completed. The internal pressure of the purge system after closing the purge adjusting means and closing the purge system, and receiving the output of the pressure detecting means and completing the process by the seal executing means. Leak determination means for determining the leak state of the purge system based on the change, and residual pressure removal for releasing the residual pressure inside the purge system to open the purge system prior to the pressure reduction processing by the pressure reduction processing execution means. Means, receiving the output of the pressure detection means,
When the internal pressure of the purge system is equal to or higher than a predetermined value immediately before the pressure reducing process is started by the pressure reducing process executing unit, at least the leak state determining process is stopped by the leak determining unit to prohibit the failure diagnosis. A failure diagnosis apparatus for an evaporated fuel processing apparatus, characterized by comprising means. 4. The failure diagnosis device for an evaporated fuel processing apparatus according to claim 1, wherein the failure diagnosis processing by the decompression processing execution means, the blockage processing execution means, and the leak determination means is performed immediately after the engine is started. 5. The residual pressure removing means opens the atmosphere opening port to release the residual pressure inside the purge system by opening the opening / closing means prior to the execution of the pressure reducing process. A failure diagnosis device for an evaporated fuel processing device according to 1, 2, 3 or 4. 6. The failure diagnosis device for an evaporated fuel processing device according to claim 5, wherein the opening / closing means is a drain cut valve. 7. The diagnosis prohibiting means prohibits the depressurization processing by the depressurization processing executing means when the internal pressure of the purge system is equal to or higher than a predetermined value immediately before the depressurization processing by the depressurization processing executing means is started. The failure diagnosis device for an evaporated fuel processing device according to claim 2 or 3.