KR100717949B1 - Method for controlling purge valve of car - Google Patents

Abstract

Discloses a purge valve control method for an automobile in which the purge valve is opened to stabilize the pressure in the fuel tank when the leak diagnosis is stopped during the leak diagnosis for the evaporation gas. In such a general automobile, when the leakage diagnosis condition is not satisfied during the leakage diagnosis of the evaporation gas, the leakage diagnosis is stopped and the state returns to the state before the leakage diagnosis. At this time, the purge amount is determined according to the engine speed and the intake air amount. If the purge valve is not immediately controlled, the pressure in the fuel tank is unstable when the flow resistance in the fuel tank is large. Accordingly, the present invention controls the purge valve based on the purge valve opening speed and opening information set in accordance with the engine load when the evaporation gas leakage diagnosis is stopped during the evaporation gas leakage diagnosis, so that even if the flow resistance is large, It is possible to stabilize the evaporation gas pressure in the evaporator.

Automobile, fuel tank, evaporative gas, leak diagnosis, purge valve

Description

TECHNICAL FIELD [0001] The present invention relates to a method of controlling a purge valve of a vehicle,

1 is a view showing an internal pressure in a fuel tank of a general automobile.

2 is a view showing a configuration of a vehicle to which the present invention is applied.

3 is a flowchart illustrating a purge valve control process of an automobile according to the present invention.

 Description of the Related Art

11: suction pipe 12: surge tank

13: engine 14: throttle valve

15: fuel tank 16: discharge pipe

17: Canister 18: Canister purge valve

19: air supply pipe 20: canister shut-off valve

21: air discharge pipe 22: filter

23: Level sensor 24: Temperature sensor

25: pressure sensor 26: engine control unit

The present invention relates to a method for controlling a purge valve in an automobile, and more particularly, to a method for stabilizing a pressure in a fuel tank by opening a purge valve when leak diagnosis is stopped during a leak diagnosis for an evaporated gas.

As is known, the internal combustion engine is a device that generates power by burning fuel and air in the engine, and thus a vehicle using the power of such an internal combustion engine has a fuel tank for storing fuel for supplying the engine .

The fuel stored in the fuel tank may vary depending on the degree of volatility. However, as time elapses, the fuel evaporates to discharge the evaporated gas. When the evaporated gas is discharged to the outside air, Pollution due to discharge of unheated gas occurs.

Accordingly, a modern automobile has an evaporative gas control system for supplying evaporative gas generated in a fuel tank to an engine. The evaporative gas control system includes a fuel tank for storing fuel of an automobile, An evaporative gas collector for collecting evaporative gas generated in the fuel tank, and a supply pipe for supplying evaporative gas of the evaporative gas collector to the engine of the automobile.

However, when leakage occurs in the evaporative gas control system, pollution caused by the evaporative gas can not be prevented. Therefore, the automobile maker is trying to detect the leakage of the evaporative gas control system.

For example, when the vehicle is stopped, the evaporation gas control system is shut off from the outside air to form a vacuum, and then the evaporation gas control system is shut off from the engine. Based on the change in the internal pressure over time, .

1 is a graph showing a pressure in a fuel tank according to a process in which a leakage detection method of a conventional evaporation gas control system is performed.

When the vehicle stops at a certain time (P1) while driving, a leakage diagnosis method according to the prior art starts and blocks the evaporation gas control system from the outside air and the engine.

Then, when the internal pressure of the fuel tank is increased to the set pressure (P2) due to the evaporation gas, the internal pressure of the evaporative gas control system is reduced to the set pressure by starting to supply the evaporative gas to the engine P3).

Thereafter, the evaporation gas control system is shut off from the engine to observe the change of the pressure in the fuel tank for the set time (40 sec), and as a result, it is judged that air is introduced from the outside air into the evaporation gas control system It is judged that there is leakage.

However, according to the related art of the related art, it takes about 5 seconds for the internal pressure P2 to increase after the time P1, and about 7 seconds for the internal pressure to decrease (P3) The time required to observe the internal pressure change with time elapses from about 16 seconds to about 28 seconds.

However, if the leakage diagnosis condition is not satisfied during the evaporative gas leakage diagnosis, the leakage diagnosis is interrupted and the system returns to the state before the leakage diagnosis. At this time, the purge amount is determined according to the engine speed and the intake air amount. If the purge valve is not immediately controlled, the pressure in the fuel tank is unstable when the flow resistance in the fuel tank is large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to provide a method and apparatus for controlling the purge valve according to an engine load when the diagnosis of evaporation gas leakage is stopped during diagnosis of evaporation gas leakage, The present invention provides a method of controlling a purge valve of an automobile.

Technical Solution According to an aspect of the present invention,

In a vehicle for diagnosing leakage of evaporative gas in a fuel tank by control of a purge valve,

a) performing a leak diagnosis for the evaporated gas satisfying a leak diagnosis condition of the evaporated gas;

b) checking whether the leak diagnosis of the evaporation gas is stopped through the step a), checking whether the leak diagnosis is completed when the stoppage is stopped, and controlling the purge valve control for stabilizing the pressure in the fuel tank when the leak diagnosis is not completed Checking whether the condition is satisfied;

c) stopping purge when the purge valve control condition is satisfied, and setting a purge control opening speed and an opening degree based on the engine load when the first predetermined time has elapsed and the pressure in the fuel tank is equal to or greater than a first predetermined value ; And

d) opening the purge valve based on the purge control opening speed and opening degree through the step c) and checking whether the purge evaporation amount is equal to or more than a target value set according to the engine load amount, And stopping the operation.

Here, the purge valve control condition in the step b) is an opening amount in a state in which the purge before the leakage diagnosis is stabilized.

The first predetermined time is a waiting time for controlling the purge valve after stopping diagnosis of the evaporated gas, and the first predetermined value is the pressure of the evaporated gas in the fuel tank for purge.

Wherein the purge control opening speed is set such that the current purge increase amount is the sum of the previous purge increase amount and the table value according to the engine load, and the engine load is a sum of the intake air amount, engine speed, fuel temperature, atmospheric pressure, The engine cooling water temperature, the elapsed time after the engine start, the vehicle running speed, and the evaporated gas volume of the fuel.

Preferably, the method further comprises the step of: (a) diagnosing the leakage of the evaporation gas when the second predetermined time has elapsed after the purging operation is stopped through the step (d).

Here, the second predetermined time may be a waiting time for re-diagnosing the leakage of the evaporative gas, and the second predetermined time may be 60 seconds or more.

According to the present invention, when the evaporative gas leakage diagnosis is stopped during the evaporative gas leakage diagnosis, the purge valve is controlled on the basis of the purge valve opening speed and opening information set in accordance with the engine load so that even when the flow resistance is large, The evaporation gas pressure can be stabilized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order to explain the present invention in detail so that those skilled in the art can easily carry out the present invention.

FIG. 2 is a view showing a configuration of a vehicle to which a purge valve control process of an automobile according to the present invention is applied, and FIG. 3 is a flowchart illustrating a purge valve control process of an automobile of the engine control block shown in FIG. The automobile to which the present invention is applied is connected to the intake port of the engine 13 through the surge tank 12 by the intake pipe 11 as shown in Fig. The intake pipe (11) is provided with a throttle valve (14). The fuel tank 15 is connected to a canister 17 through a discharge pipe 16 which is connected to the intake pipe 11 through a supply pipe 19 having a purge valve 18, A discharge pipe 21 having a shut-off valve 20 is connected. A filter 22 is attached to the distal end of the discharge pipe 21. The canister 17 temporarily stores evaporative gas (harmful substances such as HC) generated in the fuel tank 15 and sucks the evaporative gas (harmful substances such as HC) into the intake pipe 11 by operation during operation of the engine 13 . Therefore, the evaporation path of the fuel gas is formed in the order of the fuel tank 15, the discharge pipe 16, the canister 17, the supply pipe 19, and the discharge pipe 21.

The fuel tank 15 is provided with a level sensor 23, a temperature sensor 24 for detecting the fuel temperature, and a pressure sensor 25 for detecting the pressure in the evaporation path, And the sensors 23, 24 and 25 are connected to the engine control unit 26. The engine control unit 26 controls the fuel injection, the ignition timing, and the idle air amount according to the sensing signals inputted from the respective sensors, And determines whether or not each component of the vehicle is faulty. At this time, whether or not the failure of each component is recognized visually or audibly by the driver.

In the embodiment of the present invention, the purge valve 18 is opened and a negative pressure in the fuel tank 15 is formed due to the vacuum of the surge tank 12, and after a lapse of a predetermined time, 18), and is calculated through the pressure increase in the fuel tank (15).

When the leak diagnosis is stopped after the purge valve 18 is closed during the leak diagnosis, the engine control unit 26 controls the purge valve 18 .

That is, when the leak diagnosis is stopped while diagnosing the leakage of the evaporative gas in the fuel tank, and the purging state is rapidly changed to the stabilized open amount, the purge increase amount of the purge valve 18 is changed according to the engine load And controls to open until reaching a preset target value.

A purge valve control process of an automobile according to an embodiment of the present invention will now be described with reference to FIGS. 2 and 3. FIG.

First, the engine control unit 26 receives the signals of the sensors corresponding to the leak diagnosis conditions of the evaporation gas in the fuel tank, and performs leakage diagnosis if the leak diagnosis conditions of the evaporation gas are satisfied (step 101). Since the leakage diagnosis condition of the evaporation gas is a known technology, a detailed description thereof will be omitted.

After the execution of the step 101, the engine control unit 26 checks whether the leak diagnosis is stopped (step 103). If the leak diagnosis is stopped, it is checked whether or not the leak diagnosis is completed (step 105) A purge valve control process for controlling the opening of the purge valve 18 is executed.

That is, if the engine control unit 26 is stopped during the leak diagnosis of the evaporative gas through the step 105, it is checked whether the current purge amount is the stabilized open amount (step 107). If the purge is the maximum, (Step 109).

The engine controller 26 checks whether the first predetermined time (3 seconds) has elapsed (step 111), and if the first predetermined time has elapsed, the pressure in the fuel tank 15 reaches a predetermined value (-10 hPa) (Step 113) and sets the opening speed and opening degree of the purge valve 18 (step 115). Here, the first predetermined time (3 seconds) is a waiting time in which the purge valve 18 can operate, and the first predetermined value is a pressure in the fuel tank sufficient to perform purging

The opening speed of the purge valve 18 is set such that the amount of purge increase is the sum of the variables set to the table value according to the previous purge increase amount and the hydraulic air amount (engine load). The open degree is determined to be the open state of the purge valve 18 until the purged increase amount reaches a predetermined target value according to the engine load. The target value is determined according to the inflow air amount, and becomes the purge target amount until the pressure in the fuel tank 15 is stabilized to such an extent that the leakage diagnosis can be re-executed.

In the embodiment of the present invention, it is explained that the target value is determined according to the received inflow air amount, that is, the engine load. However, the engine load may vary depending on the engine speed, fuel temperature, atmospheric pressure, concentration of evaporation gas, The running time, the volume of the evaporation gas of the engine, and the like.

The engine control unit 26 controls the purge valve 18 to be in the open state based on the opening speed and the opening degree set in step 115.

Then, the engine controller 26 checks whether the purge increase amount has reached the target value (step 119), and ends the opening of the purge valve 18 when the purge evaporation amount reaches the target value (step 121). Thus, the pressure in the fuel tank 15 is stabilized.

If the second predetermined time (about 60 seconds) has elapsed after the purge valve 18 has been opened (step 123), the engine control unit 26 proceeds to step 101, Diagnose.

As described above, the purge valve control method for an automobile according to the present invention controls the purge valve based on the purge valve opening speed and opening information set in accordance with the engine load when the evaporation gas leakage diagnosis is stopped during the evaporation gas leakage diagnosis. So that the evaporation gas pressure in the fuel tank can be stabilized quickly even if the flow resistance is large.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It is, therefore, to be understood that the above-described embodiments are illustrative in all respects and not as restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (9)

In a vehicle for diagnosing leakage of evaporative gas in a fuel tank by control of a purge valve, a) performing a leak diagnosis for the evaporated gas satisfying a leak diagnosis condition of the evaporated gas; b) checking whether the leak diagnosis of the evaporation gas is stopped through the step a), checking whether the leak diagnosis is completed when the stoppage is stopped, and controlling the purge valve control for stabilizing the pressure in the fuel tank when the leak diagnosis is not completed Checking whether the condition is satisfied; c) stopping purge when the purge valve control condition is satisfied, and setting a purge control opening speed and an opening degree based on the engine load when the first predetermined time has elapsed and the pressure in the fuel tank is equal to or greater than a first predetermined value ; And d) opening the purge valve based on the purge control opening speed and opening degree through the step c) and checking whether the purge evaporation amount is equal to or more than a target value set according to the engine load amount, and stopping the opening of the purge valve when the purge evaporation amount is more than a target value Wherein the purge valve control method comprises the steps of: The purge valve control method according to claim 1, wherein the purge valve control condition in the step b) is an opening amount in a state in which the purge before the leak diagnosis is stabilized. 3. The purge valve control method for an automobile according to claim 2, wherein the first predetermined time is a waiting time for controlling the purge valve after stopping diagnosis of the evaporation gas, 4. The method of claim 3, wherein the first predetermined value is the pressure of the evaporative gas in the fuel tank for executing purge. 5. The method according to claim 4, wherein the purge control opening speed is set such that the current purge increase amount is a sum of the previous purge increase amount and the table value according to the engine load. delete The method according to any one of claims 1 to 5, further comprising the steps of: e) if the second predetermined time has elapsed after the purging operation is stopped through the step d), proceeding to step a) Further comprising the step of controlling the purge valve of the automobile. 8. The method of claim 7, wherein the second predetermined time is a waiting time for re-diagnosing leakage of the evaporative gas. The method as claimed in claim 8, wherein the second predetermined time is 60 seconds.

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