KR102468925B1 - Dual perge system diagnosis method - Google Patents

Abstract

A method for diagnosing a dual fuzzy system is disclosed. The method for diagnosing a dual fuzzy system of the present invention includes determining whether it is an operating area using a turbo charger based on an operating condition; closing the differential pressure generating valve of the fuel tank according to the pressure at the front end of the electronic throttle control valve that regulates the amount of air supplied to the engine when the operating region is an operating region using a turbo charger; and diagnosing a dual purge system according to a change in pressure inside the fuel tank while lowering the pressure inside the fuel tank by controlling a purge valve that controls fuel evaporation gas flowing into the engine.

Description

Dual purge system diagnosis method {DUAL PERGE SYSTEM DIAGNOSIS METHOD}

The present invention relates to a method for diagnosing a dual purge system, and more particularly, to a method for diagnosing a dual purge system based on whether fuel evaporation gas forms a flow rate through a dual purge line in a turbo use area.

In general, in an operating section using a turbocharger, the pressure at the rear end of the electronic throttle control valve increases due to supercharging, making it impossible for fuel evaporation gas to be purged through the existing purge line. A separate purge line and ejector have been provided to perform this operation. Such a system is called a dual purge system.

The dual purge system recirculates part of the intake air through a separate purge line by using the increased pressure at the front of the electronic throttle control valve when a turbocharger is used. Using the flow rate of the recirculated intake air, the fuel evaporation gas can be sucked into the rear end of the air cleaner through the Venturi effect.

However, in the conventional dual purge system, a pressure sensor is additionally installed in a pressure sensing line, and a purge flow rate is directly checked in the corresponding line for diagnosis. This method is effective in increasing the reliability of diagnosis because the purge flow rate can be directly checked.

However, the conventional dual purge system has a problem in that the cost of the product increases because the pressure sensor must be additionally installed as described above.

The background art of the present invention is disclosed in 'Leak Diagnosis Method of Fuel Vapor Dual Purge System' of Korean Patent Publication No. 10-2020-0003527 (2020.01.10).

The present invention was invented to improve the above problems, and an object according to one aspect of the present invention is a dual purge system for diagnosing a dual purge system based on whether fuel evaporation gas forms a flow rate through a dual purge line in a turbo use area. to provide diagnostic methods.

According to an aspect of the present invention, a method for diagnosing a dual fuzzy system includes determining, by a controller, whether an operating region is a turbo charger based driving information; closing, by the control unit, a differential pressure generating valve of a fuel tank according to a pressure at a front end of an electronic throttle control valve that adjusts an amount of air supplied to an engine when the operating region is an operating region using the turbo charger; and diagnosing a dual purge system according to a change in pressure inside the fuel tank while the control unit controls a purge valve that controls fuel evaporation gas flowing into the engine to drop the pressure inside the fuel tank. .

The step of closing the differential pressure generating valve of the fuel tank of the present invention is characterized in that the differential pressure generating valve of the fuel tank is closed according to a pressure difference between the front pressure of the electronic throttle control valve and atmospheric pressure.

In the step of closing the differential pressure generating valve of the fuel tank of the present invention, the pressure difference between the pressure at the front end of the electronic throttle control valve and the atmospheric pressure is greater than or equal to a preset pressure change setting value that causes a pressure change inside the fuel tank, and the purge It is characterized in that the differential pressure generating valve is closed when it is less than a set value for diagnosing a faulty part capable of diagnosing a faulty part of the line.

In the step of determining the dual purge system according to the change in pressure inside the fuel tank of the present invention, the pressure inside the fuel tank is lowered by adjusting the purge valve according to the required purge flow rate according to the amount of fuel and the outside temperature. to be

In the step of diagnosing the dual purge system according to the pressure change inside the fuel tank of the present invention, the state of the dual purge system is determined according to the pressure difference between the pressure inside the fuel tank and the atmospheric pressure.

The step of determining the state of the dual purge line according to the pressure change inside the fuel tank of the present invention compares the pressure difference between the pressure inside the fuel tank and the atmospheric pressure with a preset pressure difference, and according to the comparison result, the dual purge line It is characterized by determining that the system is normal or abnormal.

In the step of diagnosing the dual purge system according to the change in pressure inside the fuel tank of the present invention, if the pressure difference between the pressure inside the fuel tank and the atmospheric pressure is equal to or greater than the set pressure difference, the dual purge system is determined to be normal, and the fuel When the pressure difference between the pressure inside the tank and the atmospheric pressure is less than the set pressure difference, the dual purge system is determined to be abnormal.

A method for diagnosing a dual purge system according to another aspect of the present invention includes increasing, by a control unit, pressure of fuel evaporation gas inside a fuel tank; determining, by the control unit, whether a driving area is a driving area using a turbo charger based on the driving information; adjusting, by the control unit, a purge flow rate flowing into an engine system when the operating region is an operating region using the turbo charger; and diagnosing, by the controller, the dual purge system according to the actual air-fuel ratio of the engine system.

The step of increasing the pressure of the fuel evaporative gas inside the fuel tank of the present invention may include closing a purge valve for controlling fuel evaporative gas flowing into the engine system while the vehicle is running for a predetermined set time.

The step of adjusting the purge flow rate introduced into the engine system of the present invention may include supplying fuel boil-off gas to the engine system by adjusting a purge valve according to a required purge flow rate according to an amount of fuel and an outside temperature.

In the step of diagnosing the dual purge system of the present invention, an actual air/fuel ratio of the engine system and a target air/fuel ratio are compared, and the dual purge system is determined to be normal or abnormal according to the comparison result.

In the step of diagnosing the dual purge system of the present invention, if the actual air/fuel ratio of the engine system is lower than the target air fuel ratio by a set error or more, the dual purge system is determined to be normal, and the actual air/fuel ratio of the engine system is lower than the target air/fuel ratio. If it is not lower than the set error, it is characterized in that the dual fuzzy system is determined to be abnormal.

A method for diagnosing a dual purge system according to an aspect of the present invention can diagnose a dual purge system based on whether fuel evaporation gas forms a flow rate through a dual purge line in a turbo usage area, and secure diagnostic robustness for the dual purge line. can

The dual purge system diagnosis method according to another aspect of the present invention does not need to configure a separate sensor for detecting the purge flow rate, thereby reducing the complexity of the process and eliminating the need to perform additional diagnosis on the corresponding sensor, thereby reducing product cost and cost. Development time can be reduced.

1 is a configuration diagram of a dual purge system to which an embodiment of the present invention is applied.
2 is a block diagram of a dual fuzzy system diagnosis device to which an embodiment of the present invention is applied.
3 is a flowchart of a method for diagnosing a dual fuzzy system according to an embodiment of the present invention.
4 is a diagram showing a differential pressure change according to an operating state of a differential pressure generating valve according to an embodiment of the present invention.
5 is a flowchart of a method for diagnosing a dual fuzzy system according to another embodiment of the present invention.
6 is a diagram showing changes in a target air-fuel ratio and an actual air-fuel ratio according to operating states of a purge valve according to another embodiment of the present invention.

Hereinafter, a method for diagnosing a dual fuzzy system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

1 is a configuration diagram of a dual purge system to which an embodiment of the present invention is applied.

Referring to FIG. 1 , in the dual purge system to which an embodiment of the present invention is applied, fuel evaporation gas generated by evaporating fuel inside the fuel tank 10 is supplied to the engine system 90 .

The fuel tank 10 stores fuel, and the fuel tank 10 includes a fuel sensor 11 for detecting the amount of fuel in the fuel tank 10, and a differential pressure sensor for detecting the pressure of the fuel boil-off gas inside the fuel tank 10. (12) is installed.

The purge line 50 supplies fuel evaporation gas inside the fuel tank 10 to the engine system 90 . The purge line 50 includes the first purge line 51 to the fifth purge line 55 .

The first purge line 51 has one end connected to the fuel tank 10 and the other end connected to the canister 20 to supply fuel evaporation gas inside the fuel tank 10 to the canister 20 .

The canister 20 collects fuel evaporation gas from the fuel tank 10 . The canister 20 is connected to the differential pressure generating valve 30 through a differential pressure connecting pipe 40 .

The differential pressure generating valve 30 is normally open and generates a pressure difference between the fuel tank 10 and atmospheric pressure. The differential pressure generating valve 30 is closed when diagnosing the dual purge system. This will be described later.

The dual purge system may include any line or related parts for supplying engine evaporation gas inside the fuel tank 10 to the engine, and is not particularly limited.

Meanwhile, the second purge line 52 has one end connected to the canister 20 and the other end connected to the purge valve 60 to supply the fuel boil-off gas collected in the canister 20 to the purge valve 60.

The purge valve 60 controls the supply of fuel boil-off gas from the engine system 90 . That is, the purge valve 60 controls the purge flow rate to the engine system 90, and the amount of fuel boil-off gas supplied from the second purge line 52 to the third purge line 53, and the second purge The amount of fuel evaporation gas supplied from the line 52 to the fourth purge line 54 is controlled. The purge valve 60 may be a purge control solenoid valve (PSCV).

The third purge line 53 has one end connected to the purge valve 60 and the other end connected to the injector 70 to supply the fuel evaporation gas supplied from the purge valve 60 to the injector 70 .

The fourth purge line 54 has one end supplied to the injector 70 and the other end connected to the front end of the electronic throttle control valve 92 of the engine system 90 .

Therefore, the fuel evaporation gas supplied through the purge valve 60 may be supplied to the front end of the electronic throttle control valve 92 through the third purge line 53, the injector 70, and the fourth purge line 54. have.

The fifth purge line 55 has one end connected to the purge valve 60 and the other end connected to the rear end of the electronic throttle control valve 92 inside the engine system 90, and the fuel evaporation gas supplied from the purge valve 60. is supplied to the rear end of the electronic throttle control valve 92.

The injector 70 feeds the fuel boil-off gas to the engine system 90 according to the pressure of the fuel boil-off gas supplied to the front end of the electronic throttle control valve 92 through the third purge line 53 and the fourth purge line 54. ) is supplied to the intake pipe 94 between the turbine 91 and the air cleaner 80. The injector 70 may supply fuel evaporation gas formed in the third purge line 53 and the fourth purge line 54 to the first intake pipe 94 according to the Venturi principle.

The intake pipe 94 between the turbine 91 of the engine system 90 and the air cleaner 80 supplies the air filtered by the air cleaner 80 to the turbine 91, and in the turbo usage area As shown, the fuel evaporation gas supplied from the injector 70 is supplied to the turbine 91.

That is, when the turbo charger is used, the pressure at the front end of the electronic throttle control valve is increased so that a part of the intake air of the fourth purge line 54 is recirculated. Using the flow rate of the recirculated intake air, the fuel evaporation gas of the third purge line 53 is transferred between the rear end of the air cleaner 80, that is, between the turbine 91 of the engine system 90 and the air cleaner 80 through the Venturi effect. is sucked into the intake pipe 94 of the

An engine 93 is provided inside the engine system 90 and operates according to a control signal from an engine control unit (not shown).

In particular, a second intake pipe 94 is provided inside the engine system 90, and an electronic throttle control valve 92 is installed in the second intake pipe 94 to control the amount of air supplied to the engine 93.

The fourth purge line 54 is connected to the front end of the electronic throttle control valve 92, and the fifth purge line 55 is connected to the rear end of the electronic throttle control valve 92.

2 is a block diagram of a dual fuzzy system diagnosis device to which an embodiment of the present invention is applied.

Referring to FIG. 2 , the dual purge system diagnosis device to which an embodiment of the present invention is applied includes a driving information detector 100, an electronic throttle control valve sensor 110, a differential pressure sensor 12, a differential pressure generating valve 30, a purge It includes a valve 60, a fuel sensor 11, an outside air temperature sensor 120, and a controller 130.

The driving information detecting unit 100 detects driving information required to determine whether a driving region is a turbo usage region, such as target speed, target torque, target torque, and engine load according to the driver's operation of the accelerator pedal. The driving information sensor 100 transmits the detected driving information to the controller 130 .

The electronic throttle control valve 92 controls the amount of intake air supplied to the engine 93 according to the driver's operation of the accelerator pedal.

The differential pressure sensor 12 detects the pressure of the fuel evaporation gas inside the fuel tank 10 .

The differential pressure generating valve 30 is normally open and generates a pressure difference between the fuel tank 10 and atmospheric pressure.

The purge valve 60 controls the purge flow rate to the engine system 90 . The purge valve 60 controls the amount of fuel evaporation gas supplied from the second purge line 52 to the third purge line 53, and the fuel supplied from the second purge line 52 to the fourth purge line 54. Adjust the amount of boil-off gas.

The fuel sensor 11 detects the amount of fuel inside the fuel tank 10 .

The outside air temperature sensor 120 detects the outside temperature of the vehicle.

The control unit 130 diagnoses the failure of the dual purge line 50 and related parts based on whether fuel evaporation gas forms a flow rate through the dual purge line 50 in the turbo usage area.

To this end, the control unit 130 determines whether or not it is a turbo use area based on the driving information detector 100, and if it is a turbo use area as a result of the determination, the differential pressure sensor 12, the electronic throttle control valve sensor 110, and the fuel sensor 11 ) and the outside air temperature sensor 120, the differential pressure generating valve 30 or the purge valve 60 is controlled based on information input from at least one of them.

At this time, the controller 130 determines whether the dual purge system is normal or abnormal according to the change in pressure inside the fuel tank 10 or the actual air-fuel ratio of the engine system 90 . The controller 130 may be an engine control unit of the engine system 90 .

Hereinafter, a method for diagnosing a dual fuzzy system according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4 .

3 is a flow chart of a method for diagnosing a dual purge system according to an embodiment of the present invention, and FIG. 4 is a diagram showing a change in differential pressure according to an operating state of the differential pressure generating valve 30 according to an embodiment of the present invention.

Referring to FIG. 3 , first, the control unit 130 detects driving information through the driving information detecting unit 100 (S110). Operation information may include target speed, target torque, target torque, engine load, and the like.

The controller 130 determines whether the driving area is a turbo usage area based on the driving information detected by the driving information sensor 100 (S120).

As a result of the determination in step S120, if the operation region is the turbo usage region, the control unit 130 senses the pressure at the front end of the electronic throttle control valve 92 through the electronic throttle control valve sensor 110.

The controller 130 calculates a pressure difference between the sensed pressure at the front end of the electronic throttle control valve 92 and a preset atmospheric pressure. Atmospheric pressure may be set in advance, but may be detected through a separate atmospheric pressure sensor (not shown).

Meanwhile, the control unit 130 determines whether the pressure difference between the pressure at the front end of the electronic throttle control valve 92 and the atmospheric pressure is within a preset range (S130). That is, the control unit 130 determines that the pressure difference between the pressure at the front end of the electronic throttle control valve 92 and the atmospheric pressure is greater than or equal to a preset pressure change set value that causes a pressure change inside the fuel tank 10, and that the purge line 50 It is judged whether it is below the set value for diagnosis of faulty parts that can diagnose faulty parts.

As a result of the determination in step S130, if the pressure difference between the pressure at the front end of the electronic throttle control valve 92 and the atmospheric pressure is within the above set range, the controller 130 closes the differential pressure generating valve 30 (S140). For reference, the differential pressure generating valve 30 is always open as described above.

As the differential pressure generating valve 30 is closed, the control unit 130 detects the amount of fuel through the fuel sensor 11 and the outside air temperature through the outside air temperature sensor 120 .

The control unit 130 adjusts the purge flow rate according to the detected fuel amount and the required purge flow rate according to the outside temperature (S150) to drop the pressure of the fuel evaporation gas inside the fuel tank 10.

More specifically, the control unit 130 determines the required purge flow rate according to the detected amount of fuel and the outside temperature, and controls the purge valve 60 according to the determined required purge flow rate to supply the second purge line 52 with Fuel evaporation gas is supplied to the third purge line (53). Here, in the turbo use area, the pressure at the rear end of the electronic throttle control valve is high, so fuel evaporation gas is not supplied through the fifth purge line (55).

Meanwhile, fuel evaporation gas inside the fuel tank 10 is supplied through the first purge line 51, the canister 20, the second purge line 52, the purge valve 60, and the third purge line 53. As it is, the pressure of the fuel evaporation gas inside the fuel tank 10 is lowered. Here, when the intake pressure measured by the MAP sensor (not shown) is relatively high, the defective product of the purge line 50 may be misdiagnosed as a normal product.

Meanwhile, the controller 130 senses the pressure of the fuel boil-off gas inside the fuel tank 10 through the differential pressure sensor 12 while lowering the pressure of the fuel boil-off gas inside the fuel tank 10 as described above, and detects the pressure of the fuel boil-off gas inside the fuel tank 10. Calculate the pressure difference between the pressure of the evaporated fuel vapor and the atmospheric pressure.

Subsequently, the control unit 130 compares the pressure difference between the pressure of the fuel boil-off gas and the atmospheric pressure with the set pressure difference, and determines whether the pressure difference between the pressure of the fuel boil-off gas and the atmospheric pressure is equal to or greater than the set pressure difference (S160).

As a result of the determination in step S160, if the pressure difference between the pressure of the fuel evaporation gas and the atmospheric pressure is greater than or equal to the set pressure difference, the controller 130 determines the dual purge system to be normal (S170).

On the other hand, as a result of the determination in step S160, if the pressure difference between the pressure of the fuel evaporation gas and the atmospheric pressure is less than the set pressure difference, the controller 130 determines that the purge flow rate has not actually occurred and determines the dual purge system as abnormal ( S180).

Referring to FIG. 4, when the differential pressure generating valve 30 is closed (Close Shut Off Valve), the pressure of the fuel boil-off gas inside the fuel tank 10 sensed by the differential pressure sensor 12 is reduced. It is shown that the pressure of the fuel evaporation gas decreases (decreased pressure amount) so that the pressure difference between the pressure and the atmospheric pressure is equal to or greater than the set pressure difference. In this case, the controller 130 determines that the dual purge system is normal.

Next, a method for diagnosing a dual fuzzy system according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6 .

5 is a flow chart of a method for diagnosing a dual purge system according to another embodiment of the present invention, and FIG. 6 is a diagram showing changes in a target air-fuel ratio and an actual air-fuel ratio according to a purge valve operating state according to another embodiment of the present invention.

Referring to FIG. 5 , the controller 130 detects driving information through the driving information detecting unit 100 (S210). Operation information may include target speed, target torque, target torque, engine load, and the like.

In this process, the controller 130 closes the purge valve 60 for a set time while driving (S220).

That is, the controller 130 drives the vehicle for a set time with the purge valve 60 closed while detecting driving information through the driving information detection unit 100 .

At this time, the control unit 130 determines whether the driving area is a turbo use area based on the driving information detected by the driving information sensor 100 (S230).

As a result of the determination in step S230, if the operation region is the turbo use region, the controller 130 controls the purge valve 60 to adjust the purge flow rate (S240). In this case, the controller 130 detects the amount of fuel through the fuel sensor 11 and detects the outside temperature through the outside air temperature sensor 120 . The control unit 130 adjusts the purge flow rate according to the detected amount of fuel and the required purge flow rate according to the outside temperature to drop the pressure of the fuel evaporation gas inside the fuel tank 10 .

That is, when the vehicle travels with the purge valve 60 closed and the operating area corresponds to the turbo use area, fuel evaporation gas increases inside the fuel tank 10, but the purge valve 60 is closed. Therefore, the pressure of the fuel evaporation gas increases inside the fuel tank 10.

At this time, when the purge valve 60 is opened, the fuel evaporation gas inside the fuel tank 10 is supplied to the third purge line 53 through the second purge line 52, and the inside of the fuel tank 10 The pressure of the fuel evaporative gas is reduced.

In this case, the control unit 130 determines whether the dual purge system is normal by checking whether fuel evaporation gas is actually supplied to the third purge line 53 based on the actual air-fuel ratio.

That is, when the control unit 130 adjusts the purge flow rate by controlling the purge valve 60 as described above, the actual air-fuel ratio of the engine system 90 is detected (S250), and the actual air-fuel ratio of the engine system 90 is detected (S250). By comparing with the target air fuel ratio, it is determined whether the actual air fuel ratio of the engine system 90 is lower than the target air fuel ratio by a set error or more (S260).

As a result of the determination in step S260, if the actual air fuel ratio of the engine system 90 is lower than the target air fuel ratio by a set error or more, the controller 130 determines that the dual purge system is normal (S270).

On the other hand, as a result of the determination in step S260, if the actual air fuel ratio of the engine system 90 is not lower than the target air fuel ratio by a set error or more, for example, the actual air fuel ratio of the engine system 90 is not lower than the target air fuel ratio by a set error or more or is less than the target air fuel ratio. If it is high, the controller 130 determines that the dual purge system is abnormal (S280).

Referring to FIG. 6 , when the purge valve 60 is opened (Condition fulfilled Open the Purge valve), an error occurs between the real lambda and the target air fuel ratio (Lambda setpoint) of the engine system 90, and at this time It is shown that the gap between lambda setpoint and real lambda of the engine system 90 is lowered than the set point. In this case, the controller 130 determines that the dual purge system is normal.

As such, the dual purge system diagnosis method according to an embodiment of the present invention diagnoses whether the purge line 50 and related parts are out of order based on whether fuel evaporation gas forms a flow rate through the dual purge line 50 in the turbo use area. and diagnostic robustness for dual fuzzy systems can be secured.

The method for diagnosing a dual purge system according to an embodiment of the present invention does not need to configure a separate sensor for detecting a purge flow rate, thereby reducing the complexity of the process and eliminating the need to perform additional diagnosis on the corresponding sensor, thereby reducing the cost and cost of the product. Development time can be reduced.

Implementations described herein may be embodied in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed only in the context of a single form of implementation (eg, discussed only as a method), the implementation of features discussed may also be implemented in other forms (eg, an apparatus or program). The device may be implemented in suitable hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which is generally referred to as a processing device including, for example, a computer, microprocessor, integrated circuit or programmable logic device or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants ("PDAs") and other devices that facilitate communication of information between end-users.

Although the present invention has been described with reference to the embodiments shown in the drawings, it should be noted that this is only exemplary and various modifications and equivalent other embodiments are possible from those skilled in the art to which the technology pertains. will understand Therefore, the true technical protection scope of the present invention will be defined by the claims below.

10: fuel tank 11: fuel sensor
12: differential pressure sensor 20: canister
30: differential pressure generating valve 40: connector
50: purge line 51: first purge line
52: second purge line 53: third purge line
54: 4th purge line 55: 5th purge line
60: purge valve 70: injector
80: air cleaner 90: engine system
91: turbine 92: electronic throttle control valve
93: engine 94: intake pipe
100: driving information sensor 110: electronic throttle control valve sensor
120: outside air temperature sensor 130: control unit

Claims (12)

determining, by a controller, whether a driving area is a driving area using a turbo charger based on the driving information;
closing, by the control unit, a differential pressure generating valve of a fuel tank according to a pressure at a front end of an electronic throttle control valve that adjusts an amount of air supplied to an engine when the operating region is an operating region using the turbo charger; and
Diagnosing a dual purge system according to a change in pressure inside the fuel tank while the control unit controls a purge valve that controls fuel evaporation gas flowing into the engine to drop the pressure inside the fuel tank,
The step of closing the differential pressure generating valve of the fuel tank closes the differential pressure generating valve of the fuel tank according to the pressure difference between the pressure at the front end of the electronic throttle control valve and atmospheric pressure,
Wherein the step of diagnosing the dual purge system according to the pressure change inside the fuel tank determines the state of the dual purge system according to the pressure difference between the pressure inside the fuel tank and the atmospheric pressure. Method for diagnosing. delete The method of claim 1, wherein closing the differential pressure generating valve of the fuel tank comprises:
If the pressure difference between the pressure at the front end of the electronic throttle control valve and the atmospheric pressure is greater than or equal to the preset pressure change setting value that induces the pressure change inside the fuel tank and is less than or equal to the failure diagnosis setting value capable of diagnosing the failure part of the purge line A dual purge system diagnosis method, characterized in that for closing the differential pressure generating valve. The method of claim 1, wherein the step of determining a dual purge system according to a change in pressure inside the fuel tank comprises:
The method of diagnosing a dual purge system, characterized in that the pressure inside the fuel tank is lowered by adjusting the purge valve according to the amount of fuel and the required purge flow rate according to the outside temperature. delete The method of claim 1, wherein determining the state of the dual purge line according to the change in pressure inside the fuel tank comprises:
A dual purge system diagnosis method, characterized in that the pressure difference between the pressure inside the fuel tank and the atmospheric pressure is compared with a preset pressure difference, and the dual purge system is determined to be normal or abnormal according to the comparison result. The method of claim 6, wherein the step of diagnosing the dual purge system according to the change in pressure inside the fuel tank comprises:
If the pressure difference between the pressure inside the fuel tank and the atmospheric pressure is greater than or equal to the set pressure difference, the dual purge system is determined to be normal, and if the pressure difference between the pressure inside the fuel tank and the atmospheric pressure is less than the set pressure difference, the dual purge system is determined to be abnormal. Dual fuzzy system diagnosis method, characterized in that for determining. delete delete delete delete delete

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