KR101252776B1 - Apparatus and method for evaporative leakage diagnosis - Google Patents

Abstract

The present invention discloses an apparatus and method for diagnosing a boil-off gas leak. According to an aspect of the present invention, a method for diagnosing evaporation gas leakage by an ECU of a vehicle capable of adjusting a pressure of a surge tank above and below atmospheric pressure may include controlling a canister valve to make an internal pressure of a fuel tank to the atmospheric pressure, and then the canister valve. Closing the opening, opening the purge valve, and changing the internal pressure of the fuel tank by the pressure of the surge tank; Closing the purge valve when the internal pressure of the fuel tank is a predetermined first reference pressure higher than the atmospheric pressure when the vehicle is running; And diagnosing a leakage of the boil-off gas when the absolute value of the inclination of the internal pressure of the fuel tank over time is equal to or greater than a first predetermined inclination.

Description

Apparatus and Method for Evaporative Leakage Diagnosis

The present invention relates to a boil-off gas leakage diagnosis, and more particularly to a boil-off gas leakage diagnosis apparatus and method that can diagnose whether the fuel tank in the boil off gas leakage.

In general, an automobile using an internal combustion engine engine generates power by burning fuel stored in a fuel tank.

The fuel stored in the fuel tanks may vary in amount depending on the degree of volatility and the ambient temperature, but emits evaporative gas over time.

However, when the boil-off gas is discharged into the atmosphere, fuel is not only wasted but also polluted, and thus the vehicle is provided with an boil-off gas system that stores the boil-off gas in the canister and supplies it back to the engine.

The boil-off system consists of fuel temperature sensors, fuel tank pressure sensors, canisters, canister close valves (hereinafter referred to as "canister valves"), purge lines and purge control solenoid valves within the fuel tank. Valve, hereinafter referred to as "purge valve", and the like.

The boil-off gas system may diagnose the boil-off gas leakage by determining whether the boil-off gas leaks.

The conventional boil-off gas system closes the canister valve at idle, opens the purge valve to lower the atmospheric pressure of the fuel tank, and then closes the purge valve to detect the slope of the internal pressure of the fuel tank under vacuum in the purge line. Negative pressure (vacuum) type leak diagnosis algorithm was used to diagnose leakage.

By the way, the conventional negative pressure leakage diagnosis algorithm was only able to diagnose the leakage only when the vehicle stopped, and there was a lot of erroneous diagnosis when the leakage diagnosis was 0.5 mm or more.

Moreover, the current law stipulates whether to leak boil-off gas at least once after turning on the vehicle and before turning off the vehicle. The conventional negative pressure leakage diagnosis algorithm requires a leak diagnosis time (typically, 30 to 40). Leakage could not be diagnosed if the stop condition did not continue.

The present invention has been made in the technical background as described above, an apparatus and method for diagnosing the leakage of the evaporated gas by changing the pressure of the fuel tank by the surge tank when the vehicle is stopped as well as while the vehicle is running. Its purpose is to provide.

According to an aspect of the present invention, a method of diagnosing leakage of an evaporated gas by an engine control unit (ECU) of a vehicle capable of adjusting an internal pressure of a surge tank above atmospheric pressure and below, may be performed by controlling a canister valve. Making the internal pressure of the fuel tank to atmospheric pressure, closing the canister valve, opening a purge control solenoid valve, and changing the internal pressure of the fuel tank by the pressure of the surge tank; Closing the purge valve when the internal pressure of the fuel tank is a predetermined first reference pressure higher than the atmospheric pressure when the vehicle is running; And if the absolute value of the inclination of the internal pressure of the fuel tank over time is equal to or greater than a first predetermined inclination, making a first diagnosis that there is a leakage of boil-off gas.

In accordance with another aspect of the present invention, a method for diagnosing evaporation gas leakage by an ECU of a vehicle capable of adjusting a pressure of a surge tank above and below atmospheric pressure includes controlling a canister valve to return the internal pressure of the fuel tank to the atmospheric pressure. And then closing the canister valve and opening a purge control solenoid valve to change the internal pressure of the fuel tank by the pressure of the surge tank; Closing the purge valve and checking a slope of the internal pressure of the fuel tank over time when the internal pressure of the fuel tank is a first reference pressure equal to or greater than a predetermined atmospheric pressure when the vehicle is running; Closing the purge valve and checking a slope of the internal pressure of the fuel tank according to the time when the internal pressure of the fuel tank is a second reference pressure below the predetermined atmospheric pressure when the vehicle is stopped; Calculating an absolute value by multiplying the inclination during driving by a first weight, multiplying the inclination during multiplication by a second weight, and adding the multiplier; And diagnosing leakage of the boil-off gas by comparing the calculation result of the calculating step with a preset threshold.

In accordance with still another aspect of the present invention, there is provided an apparatus for diagnosing a boil-off gas, including: a storage unit storing a first reference pressure above a atmospheric pressure, a first slope, a second reference pressure below the atmospheric pressure, and a second slope; And checking the state information of the vehicle that can adjust the internal pressure of the surge tank above and below the atmospheric pressure, and when the vehicle is running, controlling the canister valve to make the internal pressure of the fuel tank to the atmospheric pressure, and then closing the canister valve. Opening the purge valve, raising the internal pressure of the fuel tank by the pressure of the surge tank by the first reference pressure, closing the purge valve, and the absolute value of the slope of the internal pressure of the fuel tank It is characterized in that it comprises an ECU that checks whether the first slope is greater than, and diagnoses that there is a possibility of leakage of boil off gas if the first slope is greater than.

According to the present invention, it is possible to diagnose whether or not the evaporation gas leaks when the vehicle is stopped as well as while driving the vehicle, thereby increasing the accuracy of diagnosing the leakage of the evaporation gas and reducing the probability of misdiagnosis.

1 is a view showing a diagnostic region of the boil-off gas leakage diagnostic apparatus according to the present invention.
Figure 2 is a block diagram showing a boil-off gas leakage diagnostic apparatus according to the present invention.
Figure 3a is a graph showing the pressure change, purge valve and canister valve control of the fuel tank while the vehicle is stopped.
Figure 3b is a graph showing the pressure change, purge valve and canister valve control of the fuel tank while the vehicle is stopped.
4 is a flowchart illustrating a method of diagnosing a boil-off gas leakage according to the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms " comprises, " and / or "comprising" refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a view showing a diagnostic region of the boil-off gas leakage diagnostic apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the boil-off gas leak diagnosis apparatus 10 according to an embodiment of the present invention may include a fuel tank 220, a canister 250, a purge valve 240, a canister valve 260, and a space between them. The diagnostic area (indicated by the dotted line) containing the purging line to be connected is monitored for leakage.

The present invention provides a leak diagnosis apparatus and method for a turbo engine vehicle that can adjust the pressure of a surge tank above atmospheric pressure (1 Bar) and below, or a general engine vehicle having a pressurizable component in a part of a diagnosis area. It is about.

In turbo engine vehicles, the pressure in the surge tank is regulated above atmospheric pressure while the vehicle is running (about 2 Bar) and below atmospheric pressure (about 500 hPa) while the vehicle is stopped. A case of diagnosing a leak in a vehicle will be described as an example.

Hereinafter, an evaporation gas leak diagnosis apparatus according to an embodiment of the present invention will be described with reference to FIGS. 2, 3A, and 3B.

2 is a block diagram illustrating an apparatus for diagnosing boil-off gas leakage according to an exemplary embodiment of the present invention, FIG. 3A is a graph illustrating a change in pressure of a fuel tank, a purge valve and a canister valve control while the vehicle is stopped, and FIG. 3B It is a graph showing the change in pressure of the fuel tank, the purge valve and the canister valve control while the vehicle is stopped.

As shown in FIG. 2, the boil-off gas leak diagnosis apparatus 10 according to an embodiment of the present invention includes an ECU 110 and a storage unit 120.

The storage unit 120 combines the first reference pressure and the first slope used for the leakage diagnosis while driving the vehicle, the second reference pressure and the second slope used for the leakage diagnosis while the vehicle is stopped, and the diagnosis during the vehicle driving and the stop. Store at least one of the third slopes used for one leak diagnosis. In this case, the first and second reference pressures, the first and second slopes and the third slope may be determined by experiments.

The ECU 110 checks whether the vehicle is driving or stopping by using the vehicle state information to check whether the boil-off gas is leaked by using the respective reference pressures and the reference slope when the vehicle is running and the vehicle is stopped.

Referring to FIG. 3A, when the ECU 110 determines that the vehicle is stopped, the ECU 110 controls the canister valve to make the internal pressure of the fuel tank at atmospheric pressure (1Bar), closes the canister valve, and slowly opens the purge valve. After lowering the internal pressure of the fuel tank by the second reference pressure (t1 ~ t2) by the pressure of the surge tank, close the purge valve and check whether the absolute value of the internal pressure of the fuel tank over time is greater than or equal to the second slope. If it is more than the 2nd inclination, it is diagnosed that there is leakage of the boil-off gas.

Referring to FIG. 3B, when the ECU 110 confirms that the vehicle is driving, the canister valve is controlled to make the internal pressure of the fuel tank at atmospheric pressure (1 Bar), then the canister valve is closed, and the purge valve is gradually opened to open the surge. After raising the internal pressure of the fuel tank by the first reference pressure by the pressure of the tank (t1 to t2), close the purge valve and check whether the absolute value of the inclination of the internal pressure of the fuel tank over time is greater than or equal to the first inclination. If it is more than the first slope, it is diagnosed that there is a leakage of boil off gas. At this time, the ECU 110 receives the internal pressure of the fuel tank from the pressure sensor 210 provided in the fuel tank.

When the ECU 110 diagnoses that there is a leak of boil-off gas, the ECU 110 outputs a fault code indicating the leak of the boil-off gas.

Meanwhile, the ECU 110 may output a fault code in consideration of the diagnosis result while driving the vehicle and the diagnosis result while stopping the vehicle.

<< Example of comprehensive leak diagnosis >>

The ECU 110 may output a fault code based on a diagnosis result having a higher priority among the diagnosis result while driving the vehicle and the diagnosis result while the vehicle is stopped.

The ECU 110 may output a fault code when it is confirmed that at least one of the diagnosis result while driving the vehicle and the diagnosis result while stopping the vehicle is leaking the evaporated gas.

<< Other examples of comprehensive leak diagnosis >>

The ECU 110 multiplies the first and second weights w1 and w2 by the slopes g1 and g2 of the internal pressures of the fuel tanks which are respectively checked while driving and parking the vehicle, and takes an absolute value, as shown in Equation 1 below. After calculating the comparison value Tg, it is possible to diagnose whether the boil-off gas is leaked by comparing the comparison value with a third predetermined slope. In this case, the first and second weights may be integers whose sum is one.

Hereinafter, a method of diagnosing a boil-off gas leak according to an embodiment of the present invention will be described with reference to FIG. 4. 4 is a flowchart illustrating a method of diagnosing a boil-off gas leakage according to an embodiment of the present invention.

Referring to FIG. 4, the boil-off gas leak diagnosis apparatus 10 adjusts the canister valve (eg, open-> closed-> open) to adjust the internal pressure of the fuel tank to atmospheric pressure (S410).

The boil-off gas leak diagnosis apparatus 10 gradually opens the purge valve while closing the canister valve (S420). At this time, if the purge valve is suddenly opened, an abnormality may occur in the fuel system due to the pressure difference, and thus the evaporation gas leak diagnosis apparatus 10 gradually opens the purge valve.

The boil-off gas leak diagnosis apparatus 10 checks whether the vehicle is running or stopped from the vehicle state information (S430).

The boil-off gas leak diagnosis apparatus 10 checks whether the internal pressure of the fuel tank is increased by the first reference pressure when the vehicle is running (S440).

The boil-off gas leak diagnosis apparatus 10 closes the purge valve when the internal pressure of the fuel tank is the first reference pressure, thereby making the diagnosis region close loop (S450).

The boil-off gas leak diagnosis apparatus 10 checks whether the absolute value of the slope of the internal pressure of the fuel tank is greater than or equal to the first slope for a predetermined time after closing the purge valve (S460).

The boil-off gas leak diagnosis apparatus 10 checks whether the internal pressure of the fuel tank is lowered by the second reference pressure when the vehicle is not driving, that is, while the vehicle is stopped (S480).

When the internal pressure of the fuel tank is lowered by the second reference pressure, the boil-off gas leak diagnosis apparatus 10 closes the purge valve to make the diagnosis region close loop (S490).

The boil-off gas leak diagnosis apparatus 10 checks whether the absolute value of the slope of the internal pressure of the fuel tank is greater than or equal to the second slope (S500).

If the absolute value of the inclination of the internal pressure of the fuel tank is greater than or equal to the first inclination or the absolute value of the inclination of the internal pressure of the fuel tank is greater than or equal to the second inclination while the vehicle is stopped, the evaporation gas leak diagnosis apparatus 10 It is diagnosed that there is a leak, and outputs a failure code (S470).

On the other hand, the boil-off gas leakage diagnosis apparatus 10 checks the inclination of the internal pressure of the fuel tank in step (S460) and (S500), respectively, and does not compare with the first and second slope, as shown in Equation 1, It is possible to diagnose whether the boil-off gas leaks by comparing the absolute value of the result of multiplying the gradient of the internal pressure, respectively, by the weight.

As described above, the present invention can diagnose whether or not the evaporation gas leaks when the vehicle is stopped as well as while driving the vehicle, thereby increasing the accuracy of diagnosing the leakage of the evaporation gas and reducing the probability of misdiagnosis.

While the present invention has been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the above-described embodiments. Those skilled in the art will appreciate that various modifications, Of course, this is possible. Accordingly, the scope of protection of the present invention should not be limited to the above-described embodiments, but should be determined by the description of the following claims.

Claims (8)

As a method for diagnosing evaporation gas leakage by an ECU (Engine Control Unit) of a vehicle capable of adjusting the pressure of a surge tank above and below atmospheric pressure,
Control the canister valve (Canister Close Valve) to make the internal pressure of the fuel tank to the atmospheric pressure, then close the canister valve, open the Purge Control Solenoid Valve, the fuel tank by the pressure of the surge tank Changing the internal pressure of the;
Closing the purge valve when the internal pressure of the fuel tank is a predetermined first reference pressure higher than the atmospheric pressure when the vehicle is running; And
Making a first diagnosis that there is a leakage of boil-off gas when the absolute value of the slope of the internal pressure of the fuel tank with time is equal to or greater than a first predetermined slope.
Evaporation gas leakage diagnostic method comprising a. The method of claim 1,
Closing the purge valve when the internal pressure of the fuel tank is a second reference pressure below the predetermined atmospheric pressure when the vehicle is stopped; And
If the absolute value of the inclination of the internal pressure of the fuel tank according to the time is greater than or equal to the second predetermined inclination, making a second diagnosis that there is leakage of the boil-off gas
Evaporation gas leakage diagnostic method comprising more. The method of claim 2,
Comprehensively diagnosing whether the boil-off gas is leaking by comprehensively considering a result of the first diagnosis and a result of the second diagnosis; And
When the diagnosis result of the comprehensive diagnosis step, the diagnosis of the leakage of the boil-off gas, outputting a fault code
Evaporation gas leakage diagnostic method comprising more. The method of claim 2,
Outputting a fault code if it is diagnosed that there is a leakage of the boil-off gas as a result of the first diagnosis or the second diagnosis.
Evaporation gas leakage diagnostic method comprising more. A method of diagnosing evaporation gas leakage by an ECU (Engine Control Unit) of a vehicle that can adjust an internal pressure of a surge tank above atmospheric pressure and below,
Control the canister valve (Canister Close Valve) to make the internal pressure of the fuel tank to the atmospheric pressure, then close the canister valve, open the Purge Control Solenoid Valve, the fuel tank by the pressure of the surge tank Changing the internal pressure of the;
Closing the purge valve and checking a slope of the internal pressure of the fuel tank over time when the internal pressure of the fuel tank is a first reference pressure equal to or greater than a predetermined atmospheric pressure when the vehicle is running;
Closing the purge valve and checking a slope of the internal pressure of the fuel tank according to the time when the internal pressure of the fuel tank is a second reference pressure below the predetermined atmospheric pressure when the vehicle is stopped;
Calculating an absolute value by multiplying the inclination during driving by a first weight, multiplying the inclination during multiplication by a second weight, and adding the multiplier; And
Diagnosing the leakage of the boil-off gas by comparing the calculation result of the calculating step with a preset threshold;
Evaporation gas leakage diagnostic method comprising a. A storage unit for storing a first reference pressure above atmospheric pressure, a first slope, a second reference pressure below the atmospheric pressure, and a second slope; And
Check the state information of the vehicle that can adjust the internal pressure of the surge tank above and below the atmospheric pressure and when the vehicle is running, control the canister valve to return the internal pressure of the fuel tank to the atmospheric pressure. And then close the canister valve, open a purge control solenoid valve, raise the internal pressure of the fuel tank by the first reference pressure by the pressure of the surge tank, and then close the purge valve. An ECU (Engine Control Unit) that checks whether the absolute value of the inclination of the internal pressure of the fuel tank with time is equal to or greater than the first inclination, and diagnoses that there is a possibility of leakage of boil off gas when the inclination is greater than the first inclination.
Evaporation gas leakage diagnostic device comprising a. The method of claim 6, wherein the ECU,
When the vehicle is stopped by checking the state information of the vehicle, the canister valve is controlled to make the internal pressure of the fuel tank at atmospheric pressure, and then the canister valve is closed and the purge valve is opened to open the pressure of the surge tank. Lowering the internal pressure of the fuel tank by the second reference pressure, closing the purge valve, checking whether the absolute value of the inclination of the internal pressure of the fuel tank with respect to the time is greater than or equal to the second inclination, An evaporation gas leak diagnosis device for diagnosing that there is a possibility of leakage of the evaporation gas if it is 2 slopes or more. The method of claim 7, wherein the ECU,
A fault code for determining whether the boil-off gas is leaked by comprehensively considering the possibility of leakage of the boil-off gas diagnosed while driving and stopping the vehicle, and determining that the boil-off gas is leaked, the fault code indicating the leak of the boil-off gas Evaporation gas leak diagnosis device that outputs.

Images