KR100535409B1 - An emission control method of vehicle - Google Patents

Abstract

The present invention relates to exhaust gas reduction control of a vehicle, and to determine the degree of deterioration of the catalyst from the number of reversal / lean inversions of the rear oxygen sensor and to adjust the exhaust gas recirculation amount according to the degree of deterioration of the catalyst to effectively reduce the generation of nitrogen oxides. In that,

Determining whether the water temperature satisfies the engine activation condition while maintaining engine start-up; and if the engine activation condition is satisfied, counting the rich / lean reversal count of the rear oxygen sensor for a predetermined time; Determining the degree of deterioration of the catalyst from the number of times / lean reversal, and the process of suppressing the generation of nitrogen oxides by adjusting the exhaust gas recycle amount to which the correction map is applied according to the degree of deterioration of the catalyst.

Description

Vehicle emissions control method {AN EMISSION CONTROL METHOD OF VEHICLE}

The present invention relates to the control of vehicle exhaust gas reduction, and more particularly, to determine the degree of catalyst degradation from the number of rich / lean inversions of the rear O2 sensor according to the degree of catalyst degradation. A vehicle exhaust gas control method for effectively reducing the generation of nitrogen oxides (Nox).

Due to the doubling of the gas due to the explosion of vehicles, environmental problems are in serious trouble, and due to global warming, various weather abnormalities are continuously occurring.

Therefore, each country has established strict regulations to regulate the exhaust gas of vehicles.

Basically, harmful substances generated during combustion of fuel are classified into carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (Nox). Nitrogen oxide (Nox) is divided into carbon monoxide (CO) and hydrocarbon (HC). There is always a reverse causal relationship.

In other words, emissions of carbon monoxide (CO) and hydrocarbons (HC) are the lowest in the practical power range at which the engine is activated, while nitrogen oxides (Nox) generate the most emissions, the fuel is completely burned and the engine is hot. NOx emissions increase.

Therefore, in the current vehicle, the exhaust gas recirculation (EGR) system is applied as a part of measures to reduce the emission of nitrogen oxides (Nox), and the exhaust gas is recycled to the intake machine to lower the combustion temperature in the combustion chamber. ) Is suppressed from being discharged.

Vehicle exhaust gas varies depending on the degree of catalyst deterioration. EGR control currently applied to vehicles does not take into account the degree of catalyst deterioration. There are disadvantages.

The present invention has been invented to solve the above problems, the object of which is to determine the degree of deterioration of the catalyst from the number of rich / lean reversal of the rear oxygen sensor, by applying a correction map to the EGR control according to the degree of deterioration of the catalyst By effectively reducing the generation of nitrogen oxides (Nox) to prevent environmental pollution due to the exhaust gas.

The present invention for realizing the above object comprises the steps of determining whether the water temperature satisfies the engine activation conditions in the state of maintaining the engine start-up; Countering the number of rich / lean reverse times of the rear oxygen sensor for a predetermined time when the engine activation condition is satisfied; Determining a degree of degradation of the catalyst from the number of rich / lean inversions; It provides a vehicle exhaust gas control method comprising the step of suppressing the generation of nitrogen oxides by adjusting the exhaust gas recycle amount to which the correction map is applied according to the degree of deterioration of the catalyst.

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

As can be seen in FIG. 1, the apparatus for controlling exhaust gas of a vehicle according to the present invention includes a water temperature detector 10, a rear oxygen sensor 20, a controller 30, and an EGR 40. 10) detects the temperature of the coolant in order to grasp the activation information of the engine and outputs information about it.

The rear oxygen sensor 20 is mounted at the lower end of the catalyst of the exhaust pipe and detects the concentration of oxygen contained in the exhaust gas discharged through the catalyst and outputs a signal thereof. That is, according to the concentration of oxygen contained in the exhaust gas The control unit 30 is set when the detected temperature of the cooling water satisfies an activation condition for controlling the EGR 40, for example, when the temperature of the cooling water is detected to be 65 ° C. or higher. After a predetermined time is counted and the number of reversal for the rich / lean detected by the rear oxygen sensor 20 is detected more than a predetermined number of times determined to deteriorate the catalyst and applies the correction map set in the control of the EGR (40).

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The EGR 40 is operated according to the duty signal applied from the controller 30 to recycle the exhaust gas discharged after combustion to the intake side to suppress the emission of nitrogen oxides (Nox).

In the present invention including the function as described above, the operation of suppressing the emission of nitrogen oxides (Nox) according to the degree of degradation of the catalyst is as follows.

The controller 30 detects the temperature of the coolant from the water temperature detector 10 while the engine starts to be on, and detects that the detected coolant temperature is set to a predetermined temperature determined as engine activation, for example, 65 ° C. or higher. It is judged whether or not (S101, S102, S103).

When it is determined that the engine is activated, the signal of the rear oxygen sensor 20 is read (S104) and the inversion frequency of the rich / lean reversed based on a reference value, for example, 0.5V is counted (S105).

The signal output from the rear oxygen sensor 20 outputs a signal as shown in FIG. 3 since the exhaust gas is normally purified when the catalyst is in a normal state. As shown in FIG. In this idle state, no change occurs in the signal of the rear oxygen sensor 20, but two acceleration / lean inversions are generated and output for approximately 10 seconds during acceleration with a change in rotational speed. In the case of deterioration, since the normal purification capacity of the exhaust gas is inferior, the rear oxygen sensor 20 outputs a signal as shown in FIG. 4. As illustrated, the rear oxygen sensor 20 also has a rich / lean reverse in the idle state. It outputs a signal, causing seven reach / lean inversions in approximately 10 seconds, and a front oxygen sensor during acceleration with increasing engine speed and vehicle speed. A period almost the same turn and the rich / lean inversion cycle is output.

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Therefore, it is determined whether the number of rich / lean reversal of the counter-rear oxygen sensor 20 that is counted is detected more than a predetermined number of times within a predetermined time (S106). It is determined that the purification of the oxide Nox is maintained stably, and the exhaust gas recirculation amount of the EGR 40 is controlled by applying basic map values in consideration of the engine speed, the load, the water temperature, the intake air temperature, and the like (S109).

However, if the rich / lean reversal frequency of the rear oxygen sensor 20 is detected more than a certain number of times within a predetermined time in S106, that is, as shown in the accompanying FIG. 4, the self-diagnosis information is determined (S107). It is determined whether the reversal of the rich / lean occurs a predetermined number of times (S108).

If it is determined that the reversal of the reach / lean is set by a different failure in the above, the exhaust gas recirculation amount of the EGR 40 is applied by applying a basic map value in consideration of the engine speed, load, water temperature, intake temperature, and the like. Control (S109).

However, when the self-diagnosis results in a state in which no other failure has occurred, it is determined that the catalyst is deteriorated, and then the endurance correction map is applied (S110) to control the EGR 40 according to the degree of deterioration to adjust the exhaust gas recycle amount. NOx should not be released.

In the above, the endurance correction map is set to adjust the exhaust gas recirculation amount of the EGR 40 according to the degree of deterioration of the catalyst, as can be seen in Table 1 below.

Reverse count / T 0 to 5 6 to 10 11-15 16 to 20 21-25 26 ~ Correction One 1.02 1.05 1.07 1.10 1.15

The correction value 1 means the normal state of the catalyst.

As described above, the present invention adjusts the exhaust gas recirculation amount of the EGR according to the degree of deterioration of the catalyst, thereby stabilizing the emission of nitrogen oxides to prevent pollution of the environment.

1 is a schematic structural block diagram of an apparatus for controlling exhaust gas of a vehicle according to the present invention;

2 is a flowchart of an embodiment of performing exhaust gas reduction control in a vehicle according to the present invention;

3 is a signal waveform diagram of an oxygen sensor detected in a normal catalyst of a vehicle.

4 is a signal waveform diagram of an oxygen sensor detected in a degradation catalyst of a vehicle.

Claims (4)

delete delete Determining whether the water temperature satisfies the engine activation condition while maintaining engine start-up; Countering the number of rich / lean reverse times of the rear oxygen sensor for a predetermined time when the engine activation condition is satisfied; Determining a degree of degradation of the catalyst from the number of rich / lean inversions; And controlling the production of nitrogen oxides by adjusting the amount of exhaust gas recirculation using the correction map according to the degree of deterioration of the catalyst. The method of claim 3, The exhaust gas control method of the vehicle, characterized in that the more the number of the rich / lean reversal counter for the predetermined time is determined to increase the degree of deterioration of the catalyst is increased.