KR100471206B1 - Purge concentration calculate controlling method of fuel evaporative gas - Google Patents

Abstract

The present invention relates to a control method for calculating the purge concentration of fuel boil-off gas which can prevent the purge concentration from being incorrectly calculated by calculating the purge concentration after a predetermined time after the purge of the fuel boil-off gas. The present invention provides a control method for calculating a purge concentration of fuel boil gas, comprising: detecting a purge operation state; If the purge operation is performed, detecting whether a purge start state is performed by a purge timer mode; Updating the proportional gain initial reference value (I-gain0) if the purge start state is in the purge timer mode; Comparing whether the elapsed time after the purge operation exceeds the set time; Comparing the magnitudes of the proportional gain (I-gain) and the proportional gain initial reference value (I-gain0) if the elapsed time after the purge operation exceeds the set time in the comparing step of the elapsed time; In the step of comparing the magnitude of the proportional gain, performing a control operation such that the final purge concentration is increased by increasing or decreasing the corresponding purge concentration according to the comparison of the proportional gain initial reference value I-gain0 and the proportional gain I-gain. It is made to include.

Description

PURGE CONCENTRATION CALCULATE CONTROLLING METHOD OF FUEL EVAPORATIVE GAS}

The present invention relates to fuel boil-off gas, and more particularly, to a method for controlling purge concentration of fuel boil-off gas.

Typically, evaporative emissions of gasoline fuels, like exhaust emissions, are a major contributor to air pollution, and countries regulate them.

To meet these regulations, most vehicle manufacturers use Canister Systems to reduce fuel boil-offs.

The canister system stores hydrocarbons (HC) evaporated from the fuel tank in a charcoal canister, and stores the stored hydrocarbons through a purge control solenoid valve (PCSV) according to vehicle operating conditions. It is a system that prevents the release of boil-off gas into the atmosphere by supplying it to the intake passage of the engine and performing reburn.

Here, since the amount of purge gas supplied to the engine through the purge control solenoid valve directly affects the drive capability of the engine, the amount of purge should be appropriately set.

If rich purge gas is suddenly introduced at idle or lean air is suddenly introduced, the operating conditions of the engine are too rich or lean (Too Rich or Too Lean). A combustion atmosphere is created, which may cause the engine to shut down.

To solve this problem, purge fuel amount learning is performed when purge gas enters the engine.

If the hydrocarbon concentration in the purge gas is large, the purge fuel amount learning value is increased and the final fuel injection amount through the injector is reduced as the purge fuel amount is learned.

Referring to FIG. 1, the fuel amount proportional gain (I-gain) is input to a purge controller 110, and the purge controller 110 outputs a purge concentration Pc, a purge concentration correction value, and a final fuel amount correction. Generate a signal.

During the purge fuel amount learning process, there is a process of calculating the concentration of the purge gas.

The purge concentration (Pc) is necessary to perform fuel amount correction for the purge, and if the purge concentration is incorrectly calculated, proper purge fuel amount correction will be impossible and the final air / fuel ratio (A / F) will be lean or rich, resulting in problems in operability. Can be.

The purge concentration is obtained from the following theoretical background.

First, the definition of purge rate (Pr) and purge concentration (Pc) will be described.

Purge ratio (Pr) = [purge air volume / intake air volume],

It is defined as purge concentration Pc = [purge fuel amount / purge amount].

And air-fuel ratio (A / F)

ego,

Since the feedback control is performed, the air-fuel ratio (A / F) = 14.7.

Using the above formula, to calculate the purge concentration,

Here, assuming that the fuel gas density is 3.21 g / l and the air density is 1.29 g / l,

Referring to the above equation and FIG. 2, it can be seen that the purge concentration Pc increases when the proportional gain I-gain is smaller than '1' and decreases when the purge concentration is larger than '1'.

The initial value of the proportional gain (I-gain) at the time of fuzzy introduction is always set to '1'.

The purge concentration is calculated using the shifted degree of the proportional gain (I-gain).

The proportional gain (I-gain) is designed to move at '1' when no purge gas is introduced.

If a rich purge gas is introduced, the proportional gain (I-gain) will have a value less than '1', and the concentration of the purge gas will be estimated using this.

Here, the I-gain initial reference value means a reference value for calculating the concentration of such purge gas.

Referring to Figure 3 will be described the calculation process of the final purge concentration (Pc) according to the prior art.

First, if the purge concentration Pc is close to 0% in S312, the purge controller 110 proceeds to S314 to detect a purge operation state.

If the purge operation is performed in step S314, the purge controller 110 proceeds to step S316 to compare whether the input fuel amount proportional gain exceeds the initial reference value '1'.

If the input fuel amount proportional gain does not exceed the initial reference value '1', the purge controller 110 proceeds to S318 to increase the purge concentration, and performs a control operation to reach the final purge concentration as in S320. do.

Subsequently, the purge controller 110 proceeds to S322 and terminates a series of control operations when the starting is OFF.

On the other hand, when the fuel amount proportional gain input in the above-described (S316) exceeds the initial reference value '1', the purge controller 110 proceeds to (S324) to reduce the purge concentration, and proceeds to (S326) the reduced purge concentration Is less than 0%?

The purge controller 110 proceeds to S328 when the reduced purge concentration is less than 0% in S326 and performs a control operation so that the reduced purge concentration becomes the final purge concentration.

The above-described purge concentration calculation control logic of the prior art operates normally in a steady state, but there is a possibility that an error occurs when an initial purge mode is introduced.

In the purge concentration calculation process described above, the initial reference value of the proportional gain (I-gain) during purge introduction is '1'.

If the fuel quantity proportional gain (I-gain) is moving at 0.95 at the beginning of purge introduction, the purge controller 110 shifts the proportional gain (I-gain) from '1' to '0.95' due to the rich gas initially introduced. Shift) and reflect this to the purge concentration.

At the beginning of purge introduction, the purge duty starts at 0% and increases to the final purge duty corresponding to the operating area.

That is, it is determined that the proportional gain (I-gain) is shifted by 5% due to the small amount of purge gas at the initial stage of purge introduction, and the purge concentration is excessively calculated.

The actual proportional gain (I-gain) '0.95' is not shifted by the purge gas but is at the normal (non-purge) level of the particular operating area.

For reference, the normal purge concentration is about 5-10% in normal vehicles.

However, as described above, if the concentration calculation is incorrect at the beginning of purge introduction, a purge concentration of 200% or more is calculated (in theory, the purge concentration cannot exceed 100%) and the purge fuel amount correction is performed based on the incorrectly calculated purge concentration. As a result, the air-fuel ratio (A / F) cannot be maintained.

4 shows an example of such a phenomenon that the air / fuel ratio (A / F) is sparsely controlled for about 50 seconds after purge introduction.

Such air-fuel ratio (A / F) lean can lead to bleeding (Hesitation), idle idle (stable), or even start off in severe cases.

It is an object of the present invention to provide a control method for calculating the purge concentration of fuel boil-off gas which can prevent the purge concentration from being incorrectly calculated by calculating the purge concentration after a predetermined time after the introduction of the fuel boil-off gas.

In order to achieve the above object, the present invention provides a control method for calculating the purge concentration of fuel boil gas, comprising: detecting a purge operation state; If the purge operation is performed, detecting whether a purge start state is performed by a purge timer mode; Updating the proportional gain initial reference value (I-gain0) if the purge start state is in the purge timer mode; Comparing whether the elapsed time after the purge operation exceeds the set time; Comparing the magnitudes of the proportional gain (I-gain) and the proportional gain initial reference value (I-gain0) if the elapsed time after the purge operation exceeds the set time in the comparing step of the elapsed time; In the step of comparing the magnitude of the proportional gain, performing a control operation such that the final purge concentration is increased by increasing or decreasing the corresponding purge concentration according to the comparison of the proportional gain initial reference value I-gain0 and the proportional gain I-gain. It is characterized by comprising.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. While many specific details, such as the following description and the annexed drawings, are shown to provide a more general understanding of the invention, these specific details are illustrated for the purpose of explanation of the invention and are not meant to limit the invention thereto. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

A signal input and output to and from the purge controller 510 in the purge concentration control process according to an embodiment of the present invention will be described with reference to FIG. 5.

The signal input to the purge controller 510 is a signal related to the fuel amount proportional gain (I-gain), the proportional gain initial reference value (I-gain0), and the purge timer mode (Purge Timer Mode), and is output from the purge controller 510. The signal is a signal for purge concentration Pc, purge concentration correction value, and final fuel amount correction.

Referring to FIG. 6, a purge concentration calculation control logic according to an embodiment of the present invention includes a purge fuel amount correction value (a purge correction coefficient).

In the purge concentration calculation control logic according to the related art, the purge fuel amount correction value (a purge correction coefficient) includes a shift amount of the proportional gain (I-gain) before the purge introduction.

Referring to FIG. 7, a calculation control process of the final purge concentration Pc according to an embodiment of the present invention will be described.

First, when the purge concentration Pc is close to 0% in S710, the purge controller 510 proceeds to S712 to detect a purge operation state.

If the purge operation is performed in step S712, the purge controller 510 proceeds to step S714 and detects whether the purge start state is entered by the input purge timer mode.

Here, the purge timer mode will be described.

In the fuel amount learning section, purging the fuel amount cannot be performed normally.

In general, an engine management system (EMS) repeatedly performs a purge section and a non-purge section (a fuel learning section) with a timer.

As described above, the repetition mode of the purge section and the non-purge section is called a purge timer mode.

If, at S714, the purge start state by the purge timer mode, the fuzzy controller 510 proceeds to S716 to update the proportional gain initial reference value I-gain0.

In this case, the proportional gain initial reference value I-gain0 is set to 'the proportional gain (I-gain) value immediately before introducing purge'.

As can be seen from the above-described control process, the proportional gain initial reference value in the control process of calculating the purge concentration according to the embodiment of the present invention is updated only when the purge is introduced by the purge timer mode.

Subsequently, the purge controller 510 proceeds to step S718 to compare whether the elapsed time after the purge operation exceeds the set time (1 second).

If the concentration correction is performed immediately after the introduction of the purge, the amount of variation over the proportional gain (I-gain) immediately before the introduction of the purge may adversely affect the selection of the I-gain reference value.

To prevent this, concentration calculation is performed after the set time after purge introduction to prevent incorrect calculation of the purge concentration.

If the elapsed time after the purge operation exceeds the set time in the above-described S718, the fuzzy controller 510 proceeds to S720 to determine the proportional gain I-gain and the proportional gain initial reference value I-gain0. Compare the size.

If the proportional gain initial reference value I-gain0 is greater than the proportional gain I-gain in S720, the fuzzy controller 510 proceeds to S722 to increase the purge concentration, and as in S724, the final purge Carry out a control operation to make the concentration.

Subsequently, the purge controller 510 proceeds to step S726 and terminates a series of control operations when the starting is OFF.

Meanwhile, if the proportional gain initial reference value I-gain0 is not greater than the proportional gain I-gain in S720 described above, the purge controller 510 proceeds to S728 to reduce the purge concentration, S730. Proceed to compare if the reduced purge concentration is less than 0%.

The purge controller 510 proceeds to S732 when the reduced purge concentration is less than 0% in S730 and performs a control operation so that the reduced purge concentration becomes the final purge concentration.

As described above, the embodiment of the present invention sets the initial proportional gain I-gain0 as the proportional gain (I-gain) value immediately before the purge introduction.

Prior to the description of the calculation formula of the purge concentration Pc, the definitions of the purge ratio Pr and the purge concentration Pc and the air-fuel ratio A / F are the same as in the prior art.

In addition, the air-fuel ratio A / F is 14.7 because it performs feedback control.

The calculation formula of the purge concentration according to the embodiment of the present invention will be described with reference to the above contents.

Purge concentration

It is calculated as

Here, the fuel gas density is assumed to be 3.21 g / l, and the air density is assumed to be 1.29 g / l.

Referring to the above formula for calculating the purge concentration, the purge concentration Pc is increased when the proportional gain I-gain is smaller than the proportional gain initial reference value I-gain0, and the proportional gain I-gain. It can be seen that the concentration decreases when it is larger than the proportional gain initial reference value I-gain0.

As described above, the control method for calculating the purge concentration of fuel boil-off gas according to the present invention can prevent the air-fuel ratio (A / F) from being sparsely controlled by incorrectly calculating the purge concentration at the initial stage of purge introduction of the fuel boil-off gas. .

Therefore, there is an effect that can prevent the oscillation failure (Hesitation), idle idle (stable) due to the air-fuel ratio lean and start-up off.

1 is a flow chart showing a signal input and output to the fuzzy controller in the purge concentration control process according to the prior art.

2 is a view showing the relationship between the fuzzy correction portion at the time of purge on / off (ON / OFF) according to the prior art.

3 is a flowchart illustrating a calculation control process of a final purge concentration Pc according to the prior art.

4 is a diagram illustrating a state in which a purge fuel amount correction is performed based on an incorrectly calculated purge concentration in the purge concentration control process according to the related art, thereby controlling an abnormal air / fuel ratio (A / F).

5 is a flowchart illustrating a signal input and output to a purge controller in the purge concentration control process according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship between a purge correction component when purging on and off according to an embodiment of the present invention. FIG.

7 is a flowchart illustrating a calculation control process of a final purge concentration Pc according to an embodiment of the present invention.

Claims (4)

delete delete delete In the control method for calculating the purge concentration of fuel boil-off gas, Detecting a purge operating state; If the purge operation is performed, detecting whether a purge start state is performed by a purge timer mode; Updating the proportional gain initial reference value (I-gain0) if the purge start state is in the purge timer mode; Comparing whether the elapsed time after the purge operation exceeds the set time; Comparing the magnitudes of the proportional gain (I-gain) and the proportional gain initial reference value (I-gain0) if the elapsed time after the purge operation exceeds the set time in the comparing step of the elapsed time; In the step of comparing the magnitude of the proportional gain, performing a control operation such that the final purge concentration is increased by increasing or decreasing the corresponding purge concentration according to the comparison of the proportional gain initial reference value I-gain0 and the proportional gain I-gain. Including, If the proportional gain initial reference value (I-gain0) is greater than the proportional gain (I-gain) in the step of comparing the magnitude of the proportional gain, increasing the purge concentration and performing a control operation to reach a final purge concentration; If the proportional gain initial reference value (I-gain0) is not greater than the proportional gain (I-gain) in the magnitude comparison step, reducing the purge concentration and comparing whether the reduced purge concentration is less than 0%; And if the reduced purge concentration is less than 0%, performing a control operation so that the reduced purge concentration becomes a final purge concentration. And the proportional gain initial reference value (I-gain0) is a proportional gain (I-gain) value immediately before introduction of the purge.