KR100724262B1 - Method for detecting stuck of fuel level sensor in car - Google Patents

Abstract

A fuel level sensor stuck diagnosis method for a vehicle capable of accurately diagnosing a stuck of a fuel level sensor is disclosed. A general diagnosis of fuel level sensor fixation is that when the fuel level sensor does not generate an electrical disconnection or ground short error, and the vehicle speed sensor is not abnormal, the fuel level is measured when the vehicle is driven without stopping the engine a certain distance after the vehicle is started. If the signal moved smaller than the allowable value, it was determined that the fuel level sensor was stuck. In this case, since the amount of fuel consumed is different when traveling below the specific distance or when driving the same distance depending on the driving conditions, accurate fixation diagnosis of the fuel level sensor 11 has been difficult. According to the present invention, it is possible to accurately diagnose the fixation of the fuel level sensor by monitoring the fuel level signal, which is the output signal of the fuel level sensor, and comparing the accumulated fuel consumption and the diagnostic consumption amount. It is possible to improve the reliability.

Automotive, fuel level sensor, stuck diagnosis

Description

How to diagnose fuel level sensor stuck in your car {METHOD FOR DETECTING STUCK OF FUEL LEVEL SENSOR IN CAR}

1 is a diagram showing a configuration of a vehicle to which a failure diagnosis method of a fuel level sensor according to the present invention is applied.

2A and 2B are flowcharts illustrating a fuel level sensor failure diagnosis process of the engine electronic controller illustrated in FIG. 1.

<Explanation of symbols about main part of drawing>

23: fuel level sensor 26: engine electronic controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing a failure of a fuel level sensor in an automobile, and more particularly, to a method capable of accurately diagnosing the stuck of a fuel level sensor.

For North American export models, the vehicle's engine electronic controller (ECM), required by the US environmental regulations OBD-II, requires the diagnosis of leaks from fuel evaporative gas systems.

The leak rate was initially about 1.0 mm in diameter, but now the requirements are increased to apply a leak diagnosis of about 0.5 mm in diameter at a sequential rate.

On the other hand, the negative pressure leakage diagnosis method is equipped with an on-off valve and a fuel tank pressure sensor that can seal the system during diagnosis, and applies the negative pressure of the engine intake pipe to the system, and then measures the pressure change while the system is sealed and leaks. Determine.

The leak criterion is composed of a table of fuel temperature and the amount of fuel in the fuel tank, and the leak criterion calculated by interpolation is used for the condition.

On the other hand, for a large leak such as a state where the fuel cap is opened, it is determined as a large leak when the pressure of the fuel tank does not drop below the set value during the application of the above negative pressure.

In addition, according to US Environmental Regulation OBD-II requirements, parts used for leak diagnosis of an evaporative gas system are required to diagnose a failure of each part if the leak diagnosis is stopped when the parts fail.

As a result, a failure diagnosis is performed on the fuel level sensor used as a prohibition condition for boil-off gas leakage diagnosis.

A general diagnosis of fuel level sensor fixation is that when the fuel level sensor does not generate an electrical disconnection or ground short error, and the vehicle speed sensor is not abnormal, the fuel level is measured when the vehicle is driven without stopping the engine a certain distance after the vehicle is started. If the signal moved smaller than the allowable value, it was determined that the fuel level sensor was stuck.

In this case, since the amount of fuel consumed is different when traveling below the specific distance or when driving the same distance depending on the driving conditions, accurate fixation diagnosis of the fuel level sensor 11 has been difficult.

Therefore, it is impossible to accurately determine whether the fuel level sensor is fixed by the existing method, and thus a separate method of accurately determining the fuel level sensor is required separately.

Accordingly, the present invention was created to eliminate the above problems, and an object of the present invention is to set a difference between an initial maximum value and an initial minimum value set for a predetermined time, a current maximum value and an initial maximum value received while driving, and a current minimum value. And a method for diagnosing the fixation of the fuel level sensor that can accurately diagnose the fixation of the fuel level sensor by monitoring the difference between the initial maximum value and the comparison of the fuel consumption and the diagnosis consumption, thereby improving the reliability of the diagnosis result of the fuel level sensor. To provide.

A fixation diagnostic method of the fuel level sensor according to the present invention for achieving the above object,

In the method for diagnosing the fixation of the fuel level sensor based on the fuel level signal and the fuel consumption amount supplied from the outside through the engine electronic controller,

a) receiving a fuel level signal when the fixation diagnostic condition of the fuel level sensor is satisfied after starting the engine;

b) calculating an average value of the fuel level signal values received for a predetermined time, setting the maximum value and the minimum value as the fuel level signal to the initial maximum value and the initial minimum value of the fuel level signal based on the average value and initializing the fuel consumption;

c) check whether the vehicle is running and calculate the difference between the maximum and minimum values of the received fuel level signal when the vehicle is driving, and then store the maximum and minimum calculation values, respectively. Accumulating the fuel consumption;

d) checking whether the engine is stopped and not stopping the engine. The fuel level sensor when the maximum calculated value of the fuel level signal of step c) is greater than or equal to a first predetermined value or less than or equal to a predetermined second predetermined value. Determining a normal value and comparing the accumulated fuel consumption with a preset diagnostic consumption when the maximum operation value of the fuel level signal is equal to or smaller than a first predetermined value and the second predetermined value is greater than or equal to a preset second predetermined value;

e) determining that the fuel level sensor is stuck when the accumulated fuel consumption is less than the diagnostic consumption as a result of the comparison in step d); And

f) the initial maximum value and initial minimum value of the fuel level signal of step a), the maximum and minimum calculation values of the fuel level signal of step c), and the accumulated fuel consumption And after generating, generating a flag indicating that the fuel level sensor is being diagnosed.

According to the present invention, it is possible to accurately diagnose the fixation of the fuel level sensor by monitoring the fuel level signal, which is the output signal of the fuel level sensor, and comparing the accumulated fuel consumption and the diagnostic consumption amount. It is possible to improve the reliability.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a view showing the configuration of an engine control apparatus for a vehicle to which the present invention is applied. The engine control apparatus of 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 the inlet pipe 11 through a supply pipe 19 having a purge control valve 18, through which a canister 17 is connected via an exhaust pipe 16. A discharge pipe 21 having a canister shutoff valve 20 is connected. A filter 22 is attached to the distal end of the discharge pipe 21. In addition, the canister 17 temporarily stores the evaporated gas (harmful substances such as HC) generated in the fuel tank 15 and sucks it into the intake pipe 11 by matching during operation of the engine 13. Therefore, an 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.

In addition, the fuel tank 15 is provided with a fuel level sensor 23, a temperature sensor 24 for detecting the fuel temperature, and a pressure sensor 25 for detecting pressure in the evaporation path as residual amount detecting means for detecting the fuel remaining amount. Each of the sensors 23, 24, and 25 is connected to the engine electronic controller 26, and the engine electronic controller 26 controls the fuel injection, the ignition timing, and the idle air amount according to the sensing signals input from the respective sensors. Control the engine to an optimum state and determine the failure of each part of the vehicle. That is, the engine electronic controller 26 includes a program for diagnosing the fixation of the fuel level sensor 23.

Here, in the engine electronic controller 26, the condition for diagnosing the fixation of the fuel level sensor 23 is that a predetermined time (60 seconds) has elapsed since the engine is started, and the voltage of the battery is 10V or more and 16V or less, and the fuel There is no failure determination for electric short circuit and noise of the level sensor, and there is no abnormality of the vehicle speed sensor.

When the above condition is satisfied, the engine electronic controller 26 receives and stores the fuel level signal input at predetermined time intervals, calculates an average value of the stored fuel level signal, and calculates an average value of the fuel level signal based on the average value. Set the maximum value and the minimum value as the initial maximum value and the initial minimum value, respectively.

Then, the engine electronic controller 26 checks whether the vehicle is running and calculates a difference between the maximum value and the minimum value of the fuel level signal received when the vehicle is running, and calculates a difference between the initial maximum value and the initial minimum value, respectively. Each calculation is performed and the calculated maximum and minimum calculation values are compared with a predetermined predetermined value (10%).

When the maximum calculation value is 10% or more or the minimum calculation value is -10% or less, the engine electronic controller 26 determines that the fuel level signal 23 is normal, and the maximum calculation value is 10% or less and minimum. When the calculated value is more than -10%, the accumulated fuel consumption is compared with the diagnostic consumption.

As a result of the comparison, when the accumulated fuel consumption is larger than the diagnostic consumption, the engine electronic controller 26 determines that the fuel level sensor 23 is stuck.

On the other hand, if the engine is stopped during driving and not in the diagnosis process, the initial minimum value and initial maximum value, the cumulative fuel consumption amount, the minimum calculation value and the maximum calculation value are stored and output a flag indicating that the diagnosis is in progress, and then the vehicle is driven again after stopping. In this case, the diagnosis of the fuel level sensor is continued based on the received current fuel level signal and the stored data.

In addition, when the engine is operated for a relatively short time until the diagnosis is completed, the engine electronic controller 26 stores the cumulative fuel consumption and uses it as an initial value when calculating the cumulative fuel consumption in the next run.

2A and 2B are operation flowcharts illustrating a process of diagnosing the fixation of the fuel level sensor according to the present invention, and a process of diagnosing the fixation of the fuel level sensor according to the present invention will be described with reference to FIGS. 2A and 2B.

The engine electronic controller 26 receives the fuel level signals and the signals supplied from each sensor unit (step 103) when the diagnosis condition for the fixation of the fuel level sensor is satisfied after starting the engine (step 103). Run diagnostics.

That is, the engine electronic controller 26 checks whether a predetermined time has elapsed (step 105), calculates an average value of the received fuel level signal (step 107), and based on this average value, the maximum and minimum values of the fuel level signal. Are stored as the initial maximum value and the initial minimum value, respectively (step 109). The engine electronic controller 26 then initializes fuel consumption (step 111).

In addition, the engine electronic controller 26 checks whether the vehicle is running (step 113) and calculates the difference between the initial maximum value and the initial minimum value by calculating the maximum value and the minimum value of the fuel level signal received when the vehicle is running. And calculate and store the minimum arithmetic value (step 115). The engine electronic controller 26 then accumulates and stores fuel consumption (step 117).

After that, the engine electronic controller 26 checks whether the engine is in a stopped state (step 119), and when the engine is not in the stopped state, the engine electronic controller 26 determines the maximum and minimum arithmetic values calculated and stored. The fuel level signal 23 is normal when the maximum operation value is 10% or more or the minimum operation value is -10% or less (step 121). (Step 127), the accumulated fuel consumption is compared with the diagnostic consumption when the maximum operation value is 10% or less and the minimum calculation value is -10% or more (step 123).

When the accumulated fuel consumption amount is larger than the diagnostic consumption amount as a result of the comparison through the step 123, the engine electronic controller 26 determines that the fuel level sensor 23 is stuck (step 125).

On the other hand, when the engine is stopped through the step 119 during the diagnosis process while not driving, the initial minimum value and the initial maximum value, the cumulative fuel consumption amount, the minimum calculation value and the maximum calculation value are stored (step 129). After outputting a flag indicating that it is busy (step 131), the process proceeds to step 113 above.

Before the diagnosis is completed, the cumulative fuel consumption is stored through the engine electronic controller 26 (step 133) and used as an initial value when calculating the cumulative fuel consumption on the next run.

As described above, according to the present invention, the fuel level sensor can be accurately diagnosed by monitoring the fuel level signal, which is the output signal of the fuel level sensor, and comparing the accumulated fuel consumption and diagnostic consumption. The effect of improving the reliability of the fault diagnosis result is obtained.

As such, those skilled in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing to the technical spirit or essential features of the present invention. Therefore, the above-described embodiments are to be understood in all respects as illustrative and not restrictive. The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. .

Claims (3)

In the method for diagnosing the fixation of the fuel level sensor based on the fuel level signal and the fuel consumption amount supplied from the outside through the engine electronic controller, a) receiving a fuel level signal when the fixation diagnostic condition of the fuel level sensor is satisfied after engine start; b) initializing fuel consumption and setting the maximum value and the minimum value of the fuel level signal to the initial maximum value and the initial minimum value of the fuel level signal based on the average value calculated by calculating the average value of the fuel level signal received for a predetermined time; c) check whether the vehicle is running and calculate the difference between the maximum and minimum values of the received fuel level signal when the vehicle is driving, and then store the maximum and minimum calculation values, respectively. Accumulating the fuel consumption; d) checking whether the engine is stopped and not stopping the engine. The fuel level sensor when the maximum calculated value of the fuel level signal of step c) is greater than or equal to a first predetermined value or less than or equal to a predetermined second predetermined value. Determining a normal value and comparing the accumulated fuel consumption with a preset diagnostic consumption when the maximum calculation value of the fuel level signal is equal to or smaller than a first predetermined value and the second predetermined value is greater than or equal to a preset second predetermined value; e) determining that the fuel level sensor is stuck when the accumulated fuel consumption is less than the diagnostic consumption as a result of the comparison in step d); And f) the initial maximum value and initial minimum value of the fuel level signal of step a), the maximum and minimum calculation values of the fuel level signal of step c), and the accumulated fuel consumption And generating a flag indicating that the fuel level sensor is being diagnosed after being stored. The fuel level sensor of claim 1, further comprising: g) storing the accumulated fuel consumption before the diagnosis is completed and initializing the accumulated fuel consumption at the next driving with the stored accumulated fuel consumption. Method of diagnosis of fixation. The method of claim 1, wherein the first predetermined value is 10% and the second predetermined value is -10%.

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