KR20100064782A - Emission control system and method of diesel vehicle - Google Patents

Abstract

PURPOSE: An exhaust gas control system and method for a diesel vehicle are provided to desulfurize the catalyst poisoned with sulfur and remove harmful substances from exhaust gas with a small amount of catalyst. CONSTITUTION: An exhaust gas control system for a diesel vehicle comprises an integrating meter(120), a measuring unit(130), an operating unit(150), a timer(160), and a controller(140). The integrating meter measures accumulated driving distance of a vehicle. The measuring unit measures the temperature of cooling water, the engine rpm, and the fuel injection amount. The operating unit performs sulfur removal under the control of the controller for adjusting the air-fuel ratio and the exhaust temperature. The timer measures the time of oxidation catalyst desulfurization. The controller controls the operating unit to perform oxidation catalyst desulfurization when the accumulated driving distance, the cooling water temperature, the engine rpm, and the fuel injection amount are satisfied with a desulfurization mode entry condition, and finishes the desulfurization mode after the set time of oxidation catalyst desulfurization.

Description

Exhaust gas control system and control method of diesel vehicle {EMISSION CONTROL SYSTEM AND METHOD OF DIESEL VEHICLE}

The present invention relates to an exhaust gas control system and control method of a diesel vehicle, and specifically, to control the air-fuel ratio and the exhaust temperature to prevent the activation temperature of the oxidation catalyst from rising, thereby activating the poisoned catalyst by sulfur (desulfurization). Therefore, even a small amount of catalyst can remove harmful substances contained in the exhaust gas, and in addition to platinum, palladium can be used as a catalyst to control the exhaust gas control system and control method of diesel vehicles, which can increase the price competitiveness. It is about.

In general, emission refers to a gas in which a mixture combusted from an engine is released into the atmosphere through an exhaust pipe, and such exhaust gas mainly contains harmful substances such as carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC). Contains substance.

In order to reduce the harmful substances contained in the exhaust gas, an exhaust gas control device including an exhaust gas recirculation device, a three-way catalyst, an MPI device, and an evaporative gas control device including a canister and a purge control solenoid valve are used. have.

On the other hand, since diesel vehicles completely burn fuel by using most of the inhaled air, the amount of carbon monoxide and unburned hydrocarbons contained in the exhaust gas is very small compared to gasoline vehicles. However, unlike gasoline vehicles, the exhaust gas contains a lot of nitrogen oxides and particulate matter (PM). Particulate matters such as nitrogen oxides and particulate matters have been found to be the most important pollutants that pollute the air and also cause great harm to the human body. I'm leaning.

In recent years, as emission standards of diesel vehicles have been strengthened, a diesel particulate filter (DPF) and an oxidation catalyst (DOC; Diesel) for reducing carbon monoxide, unburned hydrocarbons, and particulate matters are used as post-treatment technologies for exhaust gases. Oxidation Catalyst) has already been put into practical use, and De-NOx catalysts and SCRs have been developed to selectively reduce only nitrogen oxides.

Among them, the particulate filter is installed in an exhaust line and collects unburned diesel particulate matter discharged from the engine by using a trap, and rises above the ignition temperature to burn the particulate matter (regeneration) repeatedly. Will be performed.

Meanwhile, the oxidation catalyst device uses platinum (Pt), which is a noble metal, as a catalyst to cope with poisoning of sulfur. However, platinum, which is used as a catalyst for the oxidation catalyst, is an expensive precious metal, which increases the cost of the oxidation catalyst and reduces the price competitiveness.

Therefore, the present invention is to solve the above-mentioned problems, by controlling the air-fuel ratio and the exhaust temperature to prevent the activation temperature of the oxidation catalyst rises, thereby activating (desulfurization) the catalyst poisoned by sulfur, and accordingly a small amount It is an object of the present invention to provide an exhaust gas control system and control method for diesel vehicles that can remove harmful substances contained in the exhaust gas, and can use palladium as a catalyst in addition to platinum.

Exhaust gas control system for a diesel vehicle according to the present invention for achieving the above object, an integration meter for measuring the accumulated running distance of the vehicle; A measuring unit measuring the temperature of the coolant, the engine speed, and the fuel injection amount; An operation unit for performing oxidation catalyst desulfurization by adjusting the air-fuel ratio λ and the exhaust temperature by the control unit; A timer measuring an oxidation catalyst desulfurization execution time; When the accumulated running distance, the temperature of the coolant, the engine speed and the fuel injection amount measured by the totalizer and the measuring unit are satisfied with the desulfurization mode entry condition, the operation unit is controlled to perform the oxidation catalyst desulfurization, and the oxidation catalyst desulfurization execution time is And a controller for terminating the desulfurization mode when the set time is reached.

In addition, the exhaust gas control method of the diesel vehicle according to the present invention, when the engine is driven, comparing the running cumulative distance with a predetermined desulfurization mode entry setting distance; Determining whether the accumulated running distance exceeds a desulfurization mode entry set distance; Determining whether the desulfurization mode entry condition is satisfied when the running accumulation distance exceeds the desulfurization mode entry setting distance; A desulfurization mode control step of entering a desulfurization mode when the desulfurization mode entry condition is satisfied and controlling a condition for performing desulfurization of the oxidation catalyst; Determining whether the desulfurization performance condition is satisfied; Performing desulfurization if the desulfurization condition is satisfied; Accumulating the desulfurization execution time; Determining whether the accumulated desulfurization execution time exceeds a set time; And ending the desulfurization mode when the accumulated desulfurization execution time exceeds the set time.

The exhaust gas control system and control method of a diesel vehicle according to the present invention can control the air-fuel ratio and the exhaust temperature to prevent the activation temperature of the oxidation catalyst from rising, thereby activating (desulfurizing) the catalyst poisoned by sulfur, Accordingly, even a small amount of catalyst can remove harmful substances contained in the exhaust gas, and palladium can be used as a catalyst in addition to platinum, thereby increasing the price competitiveness.

With reference to the accompanying drawings will be described embodiments of the present invention; In this case, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a block diagram showing an exhaust gas control system of a diesel vehicle according to the present invention.

As shown in FIG. 1, the exhaust gas control system 100 of a diesel vehicle according to the present invention includes a starter switch 110, an totalizer 120 measuring a running accumulation distance of a vehicle, a temperature of a coolant, and an engine. The measuring unit 130 for measuring the number of revolutions and the fuel injection amount, the operating unit 150 for desulfurizing the oxidation catalyst by controlling the air-fuel ratio (λ) and exhaust temperature, the totalizer 120 and the measuring unit 130 And a control unit 140 for controlling the operation of the operation unit 150 according to the accumulated running distance, the temperature of the coolant, the engine speed, and the fuel injection amount.

In addition, the exhaust gas control system 100 of the diesel vehicle according to the present invention includes a timer 160 for measuring a desulfurization execution time, and the control unit 140 performs desulfurization when the desulfurization execution time reaches a set time. The operation unit 150 is controlled to terminate, that is, to terminate the desulfurization mode.

Among the above-described components, the start switch 110 is configured as a contact point of Lock / Acc / On / Start, and drives and stops the engine by supplying and cutting off power of the battery through a contact selected to the ignition switch. In this case, when the engine is driven by the start switch 110, the signal is transmitted to the controller 140, and the controller 140 accumulates the running of the vehicle from the time when the engine is driven using the totalizer 120. Measure the distance.

The totalizer 120 measures the accumulated running distance of the vehicle from the time when the engine is driven as described above, and transmits the measured accumulated running distance to the controller 140.

Although not shown in the drawing, the measurement unit 130 includes a cooling water temperature measuring gauge, an RPM gauge for measuring the engine speed through the rotation speed of the crankshaft, and an injection amount gauge for measuring the fuel injection amount of the engine, and in each gauge. The measured temperature of the coolant, the engine speed, and the fuel injection amount are transmitted to the controller 140.

The operation unit 150 controls the air-fuel ratio by adjusting the throating of the intake machine (not shown) by the control unit 140, and desulfurizes the oxidation catalyst by controlling the exhaust temperature by performing fuel injection. Play a role.

The control unit 140 desulfurizes whether the engine is detected and measured by the start switch 110, the totalizer 120, and the measurement unit 130, the running accumulation distance, the temperature of the coolant, the engine speed, and the fuel injection amount. It is determined whether the mode entry condition is satisfied, that is, whether the oxidation catalyst needs to be desulfurized, and when the oxidation catalyst needs to be desulfurized, the operation unit 150 is controlled to perform desulfurization of the oxidation catalyst.

The timer 160 measures the desulfurization execution time and transmits it to the controller 140 when the desulfurization execution time exceeds a preset time to end the desulfurization mode. In this case, in order to end the desulfurization mode, the air-fuel ratio and the exhaust temperature controlled by the operation unit 150 are required in addition to the desulfurization execution time described above, and can be terminated only when the value is greater than or equal to a preset value.

FIG. 2 is a flowchart illustrating a method for controlling an exhaust gas of a diesel vehicle according to the present invention, and the exhaust gas using the exhaust gas control system 100 of the diesel vehicle according to the present invention configured as described above with reference to FIGS. 1 and 2. Let's take a look at how to control the gas.

In the method for controlling the exhaust gas of a diesel vehicle according to the present invention, first, it is determined whether the engine is driven using the start switch 110 (S10). Exhaust gas is a gas in which the mixer combusted from the engine is discharged to the atmosphere through the exhaust pipe as described above, and is discharged only when the engine is driven.

On the other hand, when the driving signal of the engine is applied through the start switch 110, the control unit 140 measures the accumulated running distance of the vehicle from the time when the engine is driven by using the totalizer 120, and the accumulated running distance is preliminary. It is determined whether the desulfurization mode entry set distance is exceeded (S20). In this embodiment, the desulfurization mode entry setting distance is divided into 10,000 km, 20,000 km, 30,000 km, 38,000 km, and 45,000 km, and the desulfurization execution time is set to 200 sec, 220 sec, 250 sec, 280 sec, and 300 sec according to each setting distance. Adjusted.

If the vehicle continues to run and the accumulated running distance exceeds the desulfurization mode entry setting distance, it is determined whether the desulfurization mode entry condition is satisfied (S30). At this time, the desulfurization mode entry conditions in this embodiment is the case where the temperature of the cooling water is about 80 ℃ or more, the engine speed is about 2000 ~ 3500rpm, the fuel injection amount is about 20 ~ 40cc. Here, the above-described desulfurization mode entry set distance, desulfurization execution time, and desulfurization mode entry conditions are merely examples, and may be variously changed according to the state of the vehicle and the external environment.

On the other hand, if the above-mentioned desulfurization mode entry conditions are satisfied (S40), after entering the desulfurization mode, the control unit 140 controls the operating unit 150 to enter the environment in which desulfurization of the oxidation catalyst can be performed. Make

That is, the operation unit 150 performs throating and post injection of an intake machine (not shown) to control the air-fuel ratio and the exhaust temperature, which are conditions for the desulfurization of the oxidation catalyst to be performed ( S50). In more detail, the operation unit 150 controls the air-fuel ratio by controlling the throating of the intake machine (about 0.98 ± 0.05), and raises and maintains the exhaust temperature by about 600 ° C. or more to control the oxidation catalyst. By preventing the rise of the light off temperature (LOT: LOT), it creates a condition under which desulfurization of the oxidation catalyst can be carried out.

On the other hand, after the step (S50) for controlling the air-fuel ratio and the exhaust temperature, so that the desulfurization of the oxidation catalyst is carried out, it is checked whether the desulfurization performance is satisfied (S60). At this time, when the desulfurization performance condition is satisfied, desulfurization of the oxidation catalyst is performed (S70), and the desulfurization execution time is accumulated and counted (S80). On the contrary, when the desulfurization performance condition is not satisfied, the process returns to the step of adjusting the air-fuel ratio and adjusting the exhaust temperature, that is, the desulfurization mode control step (S50).

It is determined whether the accumulated desulfurization execution time is sufficient, that is, whether the accumulated desulfurization execution time exceeds the set time (S90), and when the accumulated desulfurization execution time exceeds the set time, the desulfurization mode ends (S100). At this time, if the accumulated desulfurization execution time does not exceed the set time, the process returns to step S60 to determine whether the desulfurization execution condition is satisfied, so that the desulfurization performance is continued.

Desulfurization performance conditions are divided into air-fuel ratio and exhaust temperature, 0.98 ± 0.05 for the air-fuel ratio, preferably 600 ℃ or more for the exhaust temperature. In addition, the desulfurization execution time is preferably increased as the running cumulative distance of the vehicle is increased. If the desulfurization execution time lasts too long, various problems may occur such as deterioration of fuel economy. The maximum value of is preferably set within 300 sec.

In conclusion, the exhaust gas control system and control method of the diesel vehicle according to the present invention as described above is oxidized by controlling the air-fuel ratio and the exhaust temperature according to the running distance of the diesel vehicle, the temperature of the coolant, the engine speed and the fuel injection amount By preventing the activation temperature of the catalyst from rising, it is possible to activate (desulfurize) the poisoned catalyst by sulfur, thereby removing the harmful substances contained in the exhaust gas even with a small amount of the catalyst.

In particular, a catalyst such as platinum can be used directly without oxidation coating, and in addition to expensive platinum, palladium can be used as a catalyst to increase price competitiveness.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram showing an exhaust gas control system of a diesel vehicle according to the present invention;

2 is a flowchart illustrating a method for controlling exhaust gas of a diesel vehicle according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: exhaust gas control system of diesel vehicle

110: start switch 120: totalizer

130: measuring unit 140: control unit

150: operation unit 160: timer

Claims (7)

A totalizer for measuring a running accumulation distance of the vehicle; A measuring unit measuring the temperature of the coolant, the engine speed, and the fuel injection amount; An operation unit for performing oxidation catalyst desulfurization by adjusting the air-fuel ratio λ and the exhaust temperature by the control unit; A timer measuring an oxidation catalyst desulfurization execution time; When the accumulated running distance, the temperature of the coolant, the engine speed and the fuel injection amount measured by the totalizer and the measuring unit are satisfied with the desulfurization mode entry condition, the operation unit is controlled to perform the oxidation catalyst desulfurization, and the oxidation catalyst desulfurization execution time is A controller for terminating the desulfurization mode when the set time is reached; Exhaust gas control system of a diesel vehicle comprising a. Comparing an accumulated driving distance with a preset desulfurization mode entry setting distance when the engine is driven; Determining whether the accumulated running distance exceeds a desulfurization mode entry set distance; Determining whether the desulfurization mode entry condition is satisfied when the running accumulation distance exceeds the desulfurization mode entry setting distance; A desulfurization mode control step of entering a desulfurization mode when the desulfurization mode entry condition is satisfied and controlling a condition for desulfurization of the oxidation catalyst to be performed; Determining whether the desulfurization performance condition is satisfied; Performing desulfurization if the desulfurization condition is satisfied; Accumulating the desulfurization execution time; Determining whether the accumulated desulfurization execution time exceeds a set time; Terminating the desulfurization mode if the accumulated desulfurization execution time exceeds a set time; Exhaust gas control method of a diesel vehicle comprising a. The method of claim 2, And in the determining whether the desulfurization condition is satisfied, if the desulfurization condition is not satisfied, returning to the desulfurization mode control step. The method of claim 2, If the cumulative desulfurization execution time does not exceed the set time in the step of determining whether the accumulated desulfurization execution time exceeds the set time, the exhaust gas control method of the diesel vehicle returns to the step of determining whether the desulfurization performance is satisfied. . The method according to any one of claims 2 to 4, The desulfurization execution time is set to be proportional to the running accumulation distance exhaust gas control method of a diesel vehicle. The method according to any one of claims 2 to 4, The desulfurization mode control step includes controlling the air-fuel ratio (λ) by adjusting the throating of the intake machine, and controlling the exhaust temperature by performing fuel injection (post injection). Exhaust gas control method. The method according to any one of claims 2 to 4, The desulfurization performance condition is an exhaust gas control method of a diesel vehicle, characterized in that the air-fuel ratio is 0.98 ± 0.05, the exhaust temperature is 600 ℃ or more.

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