KR100280150B1 - Reduction of emissions when misfire occurs - Google Patents

Abstract

The present invention detects a mapped correction value corresponding to a lowered engine speed and a load when misfire occurs due to a sudden decrease in engine speed, and increases the recycle amount as a duty ratio increased by the correction value to the basic EGR rate at the same time as the operation of the EGR. The present invention relates to a method for reducing exhaust gas at the time of a misfire occurrence in which a large amount of exhaust gas due to misfire is prevented by adjusting the exhaust gas to be recirculated to adjust the exhaust gas. Determining whether it is a non-operational section (S1); If it is determined that the EGR is inactive, the engine speed Ne is checked to determine whether the fluctuation range ΔNe in which the engine speed Ne decreases sharply is greater than the predetermined reference value Thr (S2 to S4). ; If it is determined in the above step that it is larger than the reference value Thr, determining that it is a misfire, and checking the engine speed Ne and the load Ev at that time (S5 to S6); Detecting a correction value Kn mapped according to the checked engine speed Ne and the load Ev (S7); Increasing the basic EGR rate EGRs by the correction value Kn to calculate the duty rate EGRp, and causing the EGR control solenoid valve to be turned on by the calculated duty rate EGRp (S8 to S9); The control process is performed such that the operation on state Td of the EGR control solenoid valve is maintained until the predetermined time Ts is reached, and the control process is performed as S10.

Description

Reduction of emissions when misfire occurs

The present invention relates to a method for reducing exhaust gas from a vehicle, and in detail, by allowing the unburned gas generated by misfire when the engine is driven to be supplied back to the intake machine through the exhaust gas recirculation system. The present invention relates to a method for reducing emissions when a misfire occurs to improve combustion power and to reduce emissions of emissions.

In general, in case of fire during engine operation, if the ignition timing is not suitable due to the failure of the spark plug or the damage of the control system, the amount of air is too much or insufficient compared to the fuel, and the temperature and pressure of the combustion chamber This is most often formed too high.

When the engine burns, the combustion engine generates a large amount of unburned gas in the combustion chamber and discharges it to the outside through the exhaust system. When such a large amount of unburned gas is discharged to the outside, it causes very serious air pollution.

On the other hand, in the vehicle, the amount of air currently supplied to the engine is higher than that of fuel, and when the temperature and pressure of the combustion chamber become high, the exhaust gas is reintroduced into the intake system to reduce the amount of nitrogen oxide (NOx) that increases in proportion to the traveling speed. The exhaust gas recirculation system (hereinafter abbreviated to EGR) is provided to further reduce the amount of nitrogen oxides (NOx) in the exhaust gas.

In other words, as shown in FIG. 3, when an electronic control unit (hereinafter, abbreviated as ECU) receives a signal from various sensors and determines that the driving state of the current engine has entered the EGR operation section, the duty is immediately received. The passage 4 is opened by the ECR valve 3 while the EGR control solenoid valve 2 is turned on by the duty control so that the negative pressure is induced from the intake machine to the EGR valve 3. It is a structure that guides a part of gas from 5) to the intake machine so that it can be supplied to the combustion chamber 6 again.

In this way, when unburned gas flowing into the intake machine is combined with fresh air, the intake filling rate in the combustion chamber 6 decreases and the combustion power decreases accordingly. As a result, the temperature and pressure of the combustion chamber 6 are reduced. The amount of generation) can be greatly reduced.

However, in addition to the above-mentioned EGR operation period, the engine speed suddenly decreases while driving, causing the combustion force to drop, causing a misfire. In the event of a misfire, a large amount of exhaust gas such as nitrogen oxides (NOx) is generated from the combustion chamber. If it is discharged to the atmosphere as it is, there is a serious problem that causes air and environmental pollution.

Accordingly, the present invention is intended to correct the above problems, and an object of the present invention is to detect a mapped correction value corresponding to a reduced engine speed and a load when a misfire occurs due to a sudden decrease in the engine speed, thereby operating the EGR. At the same time, as the duty ratio increased by the correction value to the basic EGR rate, the exhaust gas is recycled by controlling the recycle amount so that the emission of a large amount of exhaust gas due to misfire can be prevented.

In order to achieve the above object, the present invention comprises the steps of determining whether the engine is inactive period of operation EGR; Checking the engine speed if it is determined that the EGR is inactive, and determining whether a variation in which the engine speed is sharply lowered is greater than a preset reference value; If it is determined that the reference value is larger than the reference value, determining that it is a misfire and checking engine speed and load at that time; Detecting a correction value mapped according to the checked engine speed and load; Operating the EGR control solenoid valve at a duty rate increased by a correction to the base EGR rate; The operating on state of the EGR control solenoid valve is characterized by a control process which is performed as a step to be maintained until a certain time is reached.

1 is a flowchart illustrating a control flow according to the present invention.

2 is an exemplary diagram of mapping values of correction values according to the present invention.

3 is a schematic structural diagram of a conventional EGR.

* Explanation of symbols for main parts of the drawings

ΔNe: Engine speed drop fluctuation range

Kn: Correction value according to engine speed and load change

EGRp: Duty ratio for operating the EGR control solenoid valve

Td: EGR control solenoid valve operation holding time

This will be described in more detail with reference to the accompanying drawings.

1 is a view illustrating a control flow according to the present invention. The present invention allows the engine driving condition to be performed only in a non-operating section of the EGR, which is controlled according to the amount of EGR even if misfire occurs in the operating section of the EGR. This is because control is unnecessary.

Therefore, the engine first determines whether the current engine control state is a non-operational period of the EGR (S1). If the control state is the operating section of the EGR, it is controlled by the EGR control method, and if the non-operating section of the EGR is checked, the engine speed Ne is checked (S2). The number fluctuation range ΔNe is checked (S3).

It is determined whether the variation range ΔNe of the checked engine speed Ne is greater than the reference value Thr compared to the preset reference value Thr (S4), and if it is determined to be smaller than the reference value Thr, the first control step is again performed. When it is returned to the EGR operation state determination step S1, and when it is determined that it is larger than the reference value Thr, the ECU determines this as a misfire (S5) and checks the engine speed Ne and the load Ev in the lowered state (S5) S6).

At this time, the ECU detects the correction value Kn corresponding to the engine speed Ne and the load Ev checked by the mapping value Kn set in the ECU as shown in FIG. 2 (S7), Then, the duty ratio (EGRp = EGRs * Kn) is increased by increasing the detected correction value Kn to the basic EGR rate (EGRs) (S8), and the operation of the EGR control solenoid valve is turned on by the calculated duty rate (EGRp). (S7).

On the other hand, the correction value Kn becomes larger as the engine speed Ne and the load Ev increase, and this correction value Kn is mapped as a constant greater than one.

The EGR control solenoid valve operation time Td as described above is maintained until the predetermined constant reference time Ts (S10), and when the predetermined time Ts has elapsed, the engine control state is again in the EGR non-operation section. Return to the first step (S1) to determine the recognition.

Accordingly, even in a section where the EGR does not operate, the nitrogen oxide and the unburned gas that are generated in a large amount when a misfire occurs due to a sudden decrease in the engine speed Ne are set according to the engine speed Ne and the load Ev. The duty ratio (EGRp), which increases the reference EGR rate (EGRp) by Kn), opens the EGR control solenoid valve and recycles the appropriate amount of exhaust gas, resulting in a significant reduction in the amount of exhaust gas emitted to the outside. It is expected to improve the exhaust reduction performance.

Therefore, the control according to the present invention enables the EGR to be efficiently operated over the entire period in which a large amount of exhaust gas can be generated during vehicle operation, thereby significantly reducing the amount of harmful exhaust gas and at the same time returning to normal driving. By being able to perform quickly, there is a very useful effect to save fuel by preventing excessive consumption of unnecessary fuel by misfire.

Claims (1)

Determining whether the engine is in the non-operational section of the EGR during operation (S1), and if it is determined that the EGR is the non-operational section (S1), the engine speed Ne is checked by checking the engine speed Ne. Determining whether the predetermined reference value Thr is greater than the predetermined reference value Thr (S2 to S4); If it is determined in the above step that it is larger than the reference value Thr, determining that it is a misfire, and checking the engine speed Ne and the load Ev at that time (S5 to S6); The engine speed Ne and the load Ev become larger as they increase, and correspond to the engine speed Ne and the load Ev checked in the step among the correction values Kn mapped as constants greater than one. Detecting a correction value Kn (S7); Increasing the basic EGR rate EGRs by the correction value Kn to calculate the duty rate EGRr, and causing the EGR control solenoid valve to be turned on by the calculated duty rate EGRp (S8 to S9); And a step (S10) of maintaining the operation on state (Td) of the EGR control solenoid valve until the predetermined time (Ts) is reached (S10).

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