KR20220135376A - Exhaust gas reducing system and control method thereof - Google Patents

Abstract

Disclosed are an exhaust gas reduction system and a control method thereof. In accordance with one embodiment of the present invention, the exhaust gas reduction system includes: a warm up catalytic converter (WCC) installed on an exhaust line of a gasoline engine to purify exhaust gas; a first lambda sensor and a second lambda sensor disposed at the front and rear ends of the WCC, respectively, to detect a lambda value of the exhaust gas passing through the exhaust line; an under floor catalytic converter (UCC) installed in the rear of the WCC to reduce harmful substances contained in the exhaust gas; an NH_3 reduction catalyst formed at the rear end of the UCC to store oxygen; a temperature sensor measuring a catalyst temperature of the NH_3 reduction catalyst; and a control unit receiving sensing information of various sensors to perform a lambda control operation on the engine, storing oxygen, which is supplied in an increased oxygen driving condition, in the NH_3 reduction catalyst, and oxidizing ammonia (NH_3), which is generated in a rich driving condition, using the oxygen stored in the NH_3 reduction catalyst. Therefore, the present invention is capable of reducing a large amount of NH_3.

Description

Exhaust gas reduction system and its control method

The present invention relates to an exhaust gas reduction system and a control method therefor, and more particularly, to an exhaust gas reduction system and a control method thereof for responding to ammonia (NH3) regulation in gasoline engine vehicles.

In general, the governments of each country, including Europe, control pollutants in exhaust gas such as hydrocarbons (HC), nitrogen oxides (NO _x ), carbon monoxide (CO), and particulate matter/number of particles (PM/PN) for exhaust gas regulation. Emission standards are gradually being strengthened.

Accordingly, major automobile manufacturers have developed catalytic converters to effectively respond to stricter exhaust gas regulations and are producing vehicles in line with exhaust gas regulations.

For example, the exhaust system of a gasoline engine according to the conventional exhaust gas regulation (EU6) reduces exhaust gas by configuring a WCC (Warm-up Catalytic Converter) and UCC (Under floor Catalytic Converter).

On the other hand, in recent years, the emission regulation tends to be further strengthened to ^2nd EM, and in the case of EU7, the addition of ammonia (NH3) regulation is expected.

In contrast, the conventional catalyst system has a characteristic of generating a large amount of NH3 by the reaction of nitrogen monoxide (NO) and hydrogen (H2) when nitrogen monoxide (NO) is purified in a rich atmosphere. The generated NH3 is decomposed into nitrogen (N2), nitrogen monoxide (NO), and nitrous oxide (N2O) by high-temperature oxidation in a lean atmosphere.

However, in a rich atmosphere, there is a disadvantage that NH3 is present without being decomposed even at high temperatures. Reference).

Therefore, NH3 is not currently included in emission control substances, but NH3 reduction technology is required for the company's preemptive policy to protect the air environment and to respond to regulations that will be strengthened in the future.

Matters described in this background section are prepared to promote understanding of the background of the invention, and may include matters that are not already known to those of ordinary skill in the art to which this technology belongs.

An embodiment of the present invention is an exhaust gas reduction system that effectively reduces NH3 by configuring an NH3 reduction catalyst at the rear end of the UCC to store oxygen and performing rich control based on the oxygen storage amount of the NH3 reduction catalyst, and a control method therefor would like to provide

According to one aspect of the present invention, it is installed on the exhaust line of the engine WCC (Warm up Catalytic Converter) to purify the exhaust gas; a first lambda sensor and a second lambda sensor respectively disposed at the front end and rear end of the WCC to sense a lambda value of the exhaust gas passing through the exhaust line; UCC (Under floor Catalytic Converter) installed at the rear of the WCC to reduce harmful substances contained in the exhaust gas; an NH3 reduction catalyst configured at the rear end of the UCC to store oxygen; a temperature sensor for measuring a catalyst temperature of the NH3 reduction catalyst; And it receives the detection information of various sensors to control the lambda of the engine, stores oxygen supplied under operating conditions in the NH3 reduction catalyst, and stores ammonia (NH3) generated during rich operation conditions to the NH3 reduction catalyst and a control unit that oxidizes using stored oxygen.

In addition, the WCC may include a three-way catalyst (Three Way Catalyst converter) for reducing harmful substances of HC, NOx, CO, PM, and PN included in the exhaust gas by catalytic action.

In addition, the first lambda sensor detects a first lambda value (λ1) of the exhaust gas discharged from the engine and flowing into the WCC and transmits it to the controller, and the second lambda sensor is the exhaust gas discharged from the WCC The second lambda value λ2 of λ2 may be sensed and transmitted to the controller.

In addition, the NH3 reduction catalyst may be configured as a catalyst device that stores oxygen supplied during fuel cut control, and stores excess oxygen even in a rich condition in which the oxygen is lean and utilizes it for NH3 reduction.

In addition, the NH3 reduction catalyst may include an increased Oxygen Storage Capacity (OSC) characteristic compared to other catalysts for the NH3 reduction performance.

In addition, the NH3 reduction catalyst may be composed of an oxygen storage material (CeO2) in 30% or more of the catalyst coating amount or an excess oxygen storage material of 30 g/L or more for the high OSC characteristics.

In addition, the control unit may control the lambda in a range in which the amount of residual oxygen of the NH3 reduction catalyst is not exhausted.

In addition, the control unit may perform at least one of reducing the rich operation time or reducing the degree of richness according to the amount of residual oxygen of the NH3 reduction catalyst under the rich operation condition.

On the other hand, the method of controlling the exhaust gas reduction system of the control unit that purifies the exhaust gas using the WCC (Warm up Catalytic Converter), the UCC (Under floor Catalytic Converter) and the NH3 reduction catalyst configured at the rear end of the UCC installed on the exhaust line of the engine is ; b) detecting an oxygen exhaustion condition of the NH3 reduction catalyst in which the first lambda value (λ1) is 1 or less and the second lambda value (λ2) is equal to or greater than a predetermined value; c) calculating the reducing agent supply amount (R1) according to the exhaust flow rate and the first lambda value (λ1); d) calculating the residual oxygen amount (S1) of the NH3 reduction catalyst with reference to an oxygen storage amount map (OSC MAP) based on the exhaust flow rate and catalyst temperature; And e) when the reducing agent supply amount (R1) divided by the residual oxygen amount (S1) meets the condition that is less than a constant value (a) of 1 or more, the amount of residual oxygen of the NH3 reduction catalyst is not exhausted; includes

In addition, before step a), the method may further include the step of storing oxygen supplied under operating conditions in the NH3 reduction catalyst.

Also, step b) may include oxidizing ammonia (NH3) generated under the rich driving condition using oxygen stored in the NH3 reduction catalyst.

In addition, the step c) may include deriving the concentrations of CO, CO2, and H2 according to the first lambda value (λ1); calculating the amount of reducing agent over time by multiplying the exhaust flow rate by the value obtained by multiplying the concentration of the reducing agent (i) and the reducing agent (i) density to be input according to the concentrations of the CO, CO2, and H2; and calculating the reducing agent supply amount (R1) by accumulating the amount of reducing agent over time.

In addition, step d) may include calculating the amount of residual oxygen (S1) as a value obtained by subtracting the amount of oxygen reacted with the reducing agent from the amount of oxygen of the NH3 reduction catalyst derived from the OSC MAP.

In addition, in step e), the first lambda value (λ1) is multiplied by a constant value (b) of 1 or more to perform NH3 reduction lambda control to a value higher than the first lambda value (λ1) to reduce the fuel amount and air amount This may include augmenting.

In addition, the step e) may further include reducing the rich operation time compared to the basic rich operation time when controlling the NH3 reduction lambda.

According to an embodiment of the present invention, there is an effect that a large amount of NH3 generated in a high temperature rich atmosphere can be reduced by storing oxygen through the NH3 reduction catalyst at the rear end of the UCC and controlling the lambda using the same.

In addition, there is an effect that can satisfy future NH3 regulations through the NH3 reduction technology of gasoline engine vehicles.

In addition, by preemptively securing NH3 reduction technology, it can be expected to improve the quality of environmentally friendly products and improve customer satisfaction.

1 schematically shows the configuration of an exhaust gas reduction system according to an embodiment of the present invention.
2 shows a graph of NH2 concentration and reaction rate according to general temperature and atmosphere, and NH3 generation/removal reaction equation.
3 is a flowchart schematically illustrating a method for controlling an exhaust gas reduction system according to an embodiment of the present invention.
4 is a graph showing a CO concentration according to lambda according to an embodiment of the present invention.
5 shows an oxygen storage amount map of the NH3 reduction catalyst according to an embodiment of the present invention.
6 is a graph showing the effect through the control of the exhaust gas reduction system according to the embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, terms such as “…unit”, “…group”, and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. have.

Throughout the specification, terms such as first, second, A, B, (a), (b), etc. may be used to describe various elements, but the elements should not be limited by the terms. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms.

Throughout the specification, when an element is referred to as 'connected' or 'connected' to another element, it may be directly connected to or connected to the other element, but another element may exist in between. It should be understood that there may be On the other hand, when it is mentioned that a certain element is 'directly connected' or 'directly connected' to another element, it should be understood that there is no other element in the middle.

Throughout the specification, terms used are merely used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

Throughout the specification, terms related to 'comprising', 'having', etc. are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification is present, but one or more other features. It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise herein, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as being consistent with the contextual meaning of the related art, and shall not be construed in an ideal or overly formal meaning unless explicitly defined herein.

Now, an exhaust gas reduction system and a control method thereof according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 schematically shows the configuration of an exhaust gas reduction system according to an embodiment of the present invention.

Referring to FIG. 1 , an exhaust gas reduction system 100 according to an embodiment of the present invention includes an engine 110 , an exhaust line 120 , a warm up catalytic converter (WCC) 130 , and an underfloor catalyst. It includes a converter (Under floor Catalytic Converter, UCC) (140), NH3 reduction catalyst (145) and the control unit (150).

The output of the engine 110 is controlled by the control of the controller 50 , and is driven to an optimal operating point according to the control of the controller 50 .

The engine 110 converts chemical energy into mechanical energy by burning fuel and air. That is, the engine 110 introduces air into the plurality of combustion chambers 111 through the intake manifold and injects fuel through the injectors 112 provided in each combustion chamber 111 . The engine 110 may be a gasoline direct injection (GDI) engine.

Exhaust gas generated in the combustion process of the engine 110 is collected in the exhaust manifold and then discharged to the outside through the exhaust line 120 . The exhaust gas includes regulated substances such as hydrocarbons (HC), nitrogen oxides (NOx), carbon monoxide (CO), and particulate matter/number of particles (PM/PN).

The WCC 130 may include a three-way catalyst converter installed on the exhaust line 120 to purify the exhaust gas.

The WCC 130 reduces harmful substances such as HC, NOx, CO, PM/PN, etc. included in the exhaust gas discharged from the engine 110 by catalytic action. For example, the three-way catalyst can convert HC, CO, and NOx in exhaust gas into H20 and CO2, CO into CO2, and NOx into N2 and O2 through an oxidation reaction.

The WCC 130 is a first lambda sensor 131 and a second lambda sensor that detects a lambda value according to an air-fuel ratio (AFR) of the exhaust gas passing through the exhaust line 120 at positions disposed at the front end and the rear end, respectively. and a lambda sensor 132 .

The first lambda sensor 131 senses the first lambda value λ1 of the exhaust gas discharged from the engine 110 and flowing into the WCC 130 , and transmits it to the controller 150 .

The second lambda sensor 132 detects the second lambda value λ2 of the exhaust gas discharged from the WCC 130 (or introduced into the UCC 140 ) and transmits it to the controller 150 .

Accordingly, the control unit 150 can control the injector 112 using the first lambda value λ1 and the second lambda value λ2, and information such as the fuel cut-off state of the injector 112 is displayed. can judge

The UCC 140 is installed on the exhaust line 120 at the rear of the WCC 130 to reduce harmful substances contained in the exhaust gas, and is additionally configured at the rear end to store oxygen NH3 reduction catalyst 145 . and a temperature sensor 146 .

The NH3 reduction catalyst 145 stores oxygen supplied in an oxygen-rich or increased operating condition (eg, fuel cut off).

In addition, the NH3 reduction catalyst 145 is configured as a catalyst device that can store a large amount of oxygen and use it to reduce NH3 even in a rich condition in which oxygen is rare.

The NH3 reduction catalyst 145 has a high Oxygen Storage Capacity (OSC) characteristic, which is increased compared to other catalysts (eg, WCC) for NH3 reduction performance. For example, the NH3 reduction catalyst 145 comprises an oxygen storage material (CeO2) in 30% or more of the catalyst coating amount or an excess oxygen storage material of 30 g/L or more in order to store and release excess oxygen due to the high OSC characteristics. can be configured.

The temperature sensor 146 measures the catalyst temperature of the NH3 reduction catalyst 145 and transmits it to the controller 150 .

The control unit 150 is a computing device (Electronic Control Unit, ECU) for controlling the overall operation of the exhaust gas reduction system 100 for responding to the NH3 regulation of a gasoline engine vehicle according to an embodiment of the present invention, and for this, at least one It includes processors, programs and data.

The controller 150 may calculate the exhaust flow rate based on the flow rate of air introduced into the engine 110 .

The control unit 150 controls fuel cut to block fuel injection during deceleration in order to improve fuel efficiency of the vehicle.

The control unit 150 receives the information sensed by the various sensors while the engine 110 is running and controls the amount of fuel injected by the injector 112 of the engine 110 (ie, the fuel injection amount), hereinafter, this is a lambda control ( Lambda control).

The control unit 150 controls the lambda control of the gasoline engine 110 based on the stoichiometric air-fuel ratio of 14.7:1, and calculates the fuel amount based on the amount of air introduced into the combustion chamber 111 .

Here, lambda is a ratio of the actual air-fuel ratio to the stoichiometric air-fuel ratio, and is a value obtained by dividing the air-fuel ratio of the mixer sucked into the engine by the stoichiometric air-fuel ratio. In this way, the richness of the mixer can be expressed through the lambda value (λ), which is the ratio of the air-fuel ratio. For example, when the lambda value (λ) is 1 (λ = 1), it means that the stoichiometric air-fuel ratio (14.7:1) is controlled. In addition, when the lambda value (λ) is less than 1 (λ > 1), it means that the mixer is controlled in a lean Lean atmosphere condition, and conversely, when the lambda value (λ) exceeds 1 (λ < 1) may mean that the mixer is controlled in a rich rich atmosphere condition.

Meanwhile, FIG. 2 shows a graph of NH2 concentration and reaction rate according to general temperature and atmosphere, and NH3 generation/removal reaction equation.

Referring to FIG. 2 , as described in the prior art background of the invention, in the case of a conventional gasoline catalyst system, the generation of NH3 according to the temperature increase during purification under a lean condition is reduced, and the generated NH3 is also at a high temperature. It is readily reduced by reaction with oxygen.

However, NH3 generation is easy during purification under rich conditions, but there is a problem in that NH3 cannot be removed and discharged into the atmosphere because there is no oxygen. This is due to the insufficient amount of oxygen for removing the NH3 compared to the excessive generation of NH3 in the rich condition.

Therefore, it is very important to effectively supply oxygen for the removal of NH3 in the rich condition.

The control unit 150 stores oxygen supplied in an operating condition in which oxygen is increased, such as fuel cut off, in the NH3 reduction catalyst 145 configured at the rear end of the UCC 140 . In addition, NH3 reduction control is performed to oxidize NH3 generated under a rich operating condition using oxygen stored in the NH3 reduction catalyst 145 .

Meanwhile, the controller 150 may control the rich time or the rich-time lambda value based on the amount of oxygen stored in the NH3 reduction catalyst 145 in order to effectively remove NH3 in the exhaust gas through the NH3 reduction control.

For example, in the NH3 reduction control, the reducing agent supplied to the NH3 reduction catalyst 145 of the UCC 140 (that is, the reaction with oxygen from the point in time when the second lambda value λ2 becomes a predetermined value (0.5) in the rich driving condition) This means that the oxidized substance) consumes the stored oxygen. At this time, as the amount of residual oxygen stored in the NH3 reduction catalyst 145 of the UCC 140 is reduced, the NH3 reduction performance is also reduced.

The control unit 150 controls the lambda in a range in which the amount of residual oxygen of the NH3 reduction catalyst 145 is not exhausted.

The control unit 150 may perform at least one lambda control of shortening the rich operation time or alleviating the degree of richness (lambda value) according to the amount of residual oxygen of the NH3 reduction catalyst 145 under the rich operation condition.

Accordingly, the control unit 150 can effectively reduce NH3 through the lambda control based on the amount of oxygen remaining in the NH3 reduction catalyst 145 .

On the other hand, the control unit 150 controls the lambda in a range in which the amount of residual oxygen of the NH3 reduction catalyst 145 is not exhausted.

According to the above description, the control unit 150 may be implemented as one or more processors operating according to a set program, and the set program is an exhaust gas reduction system control method for NH3 reduction of a gasoline engine vehicle according to an embodiment of the present invention It may be programmed to perform each step of

Such an exhaust gas reduction system control method will be described in more detail with reference to the drawings below.

3 is a flowchart schematically illustrating a method for controlling an exhaust gas reduction system according to an embodiment of the present invention.

Referring to FIG. 3 , the controller 150 of the exhaust gas reduction system 100 according to an embodiment of the present invention collects detection information required for NH3 reduction control from various sensors while the vehicle is being driven.

For example, the control unit 150 may collect the first lambda value λ1 and the second lambda value λ2 from the first lambda sensor 131 and the second lambda sensor 132 installed at the front and rear ends of the WCC 130 . It can be (S110).

The control unit 150 determines whether the oxygen exhaustion condition in which the first lambda value (λ1) measured at the front end of the WCC 130 is 1 or less and the second lambda value (λ2) at the rear end is a predetermined value (eg, 0.5) or more is satisfied If it is not satisfied by checking (S120; No), it returns to step S110 and continues the collection.

When the first lambda value (λ1) of the front end and the second lambda value (λ2) of the rear end of the WCC 130 collected in real time satisfy the oxygen exhaustion condition (S120; Yes), the control unit 150 performs a rich operation condition. It is determined that the oxygen stored in the NH3 reduction catalyst 145 of the UCC 140 is exhausted.

The control unit 150 calculates the reducing agent supply amount (R1) according to the exhaust flow rate of the exhaust gas and the first lambda value (λ1) (S130).

More specifically, the control unit 150 may calculate the amount of the reducing agent according to the exhaust flow rate of the exhaust gas and the first lambda value (λ1) as shown in Equation 1 below.

At this time, when the first lambda value λ1 is determined, concentrations of CO, CO2, H2, etc. are determined accordingly.

For example, FIG. 4 is a graph showing the CO concentration according to lambda according to an embodiment of the present invention.

Referring to FIG. 4 , an example of deriving the CO concentration according to the first lambda value λ1 through a graph is shown, and the concentrations of CO2 and H2 may be derived in the same manner.

And, as shown in Equation 2 below, the amount of reducing agent over time can be calculated by multiplying the exhaust flow rate by the value obtained by multiplying the reducing agent (i) concentration and the reducing agent (i) density input according to the concentrations of CO, CO2, and H2.

Then, the control unit 150 may calculate the total reducing agent supply amount (R1) by accumulating the amount of the reducing agent over time.

In addition, the controller 150 calculates the residual oxygen amount S1 of the current NH3 reduction catalyst 145 with reference to the oxygen storage amount map OSC MAP based on the exhaust flow rate and the catalyst temperature (S140).

5 shows an oxygen storage amount map of the NH3 reduction catalyst according to an embodiment of the present invention.

5, the oxygen storage amount map (OSC MAP) of the NH3 reduction catalyst stores the amount of oxygen of the NH3 reduction catalyst through statistical analysis according to the change of the exhaust flow output from the engine and the catalyst temperature of the NH3 reduction catalyst 145. .

In addition, the control unit 150 may calculate the amount of oxygen reacted with the reducing agent according to the supply amount of the reducing agent. At this time, the most influential of the reducing agents can be calculated considering CO and H2. For example, since CO + 1/2 O2 considers CO2, and H2 + 1/2 O2 considers CO2 reaction, it can be calculated that each molecule of CO and H2 reacts and consumes O2 molecules.

At this time, the control unit 150 may calculate the residual oxygen amount (S1) of the current NH3 reduction catalyst 145 as a value obtained by subtracting the amount of oxygen reacted with the reducing agent from the amount of oxygen of the NH3 reduction catalyst derived from the OSC MAP.

If the control unit 150 does not satisfy the condition that the value obtained by dividing the reducing agent supply amount (R1) by the oxygen storage amount (S1) is less than the (a) value (S150; no), return to step S130 and in time Then perform the following calculations.

On the other hand, the control unit 150 satisfies the condition that the value obtained by dividing the reducing agent supply amount (R1) by the oxygen storage amount (S1) is less than a constant value (a) of 1 or more (S150; Yes), the oxygen storage amount (S1) compared to the reducing agent Since the supply amount R1 increases, it is determined as a rich operation condition in which NH3 is generated and is not reduced.

The control unit 150 performs NH3 reduction lambda control to relieve the degree of richness so that the amount of residual oxygen of the NH3 reduction catalyst 145 is not exhausted.

For example, when controlling the NH3 reduction lambda, the controller 150 may multiply the first lambda value λ1 by a constant value b of 1 or more to control the NH3 reduction lambda to be higher than the first lambda value λ1. Through this, it is possible to form a lean condition in which the amount of fuel is reduced and the amount of air is increased.

In addition, the control unit 150 may reduce the current rich operation time compared to the basic rich operation time during the NH3 reduction lambda control.

On the other hand, Figure 6 is a graph showing the effect through the control of the exhaust gas reduction system according to the embodiment of the present invention.

Referring to FIG. 6 , when the NH3 reduction control of the gasoline engine 110 is performed by applying the exhaust gas reduction system according to an embodiment of the present invention, the WCC 130 , the UCC 140 , and the NH3 reduction catalyst 145 respectively It shows the result of comparing the output NH3 emissions (mg/km).

As a result, the NH3 purification rate (%) compared to the WCC 130 was improved by 23% in the UCC 140 and 78% in the NH3 reduction catalyst 145, confirming that the purification rate was greatly improved.

As such, according to an embodiment of the present invention, there is an effect that a large amount of NH3 generated in a high temperature rich atmosphere can be reduced by storing oxygen through the NH3 reduction catalyst at the rear end of the UCC and controlling the lambda using the same.

In addition, there is an effect that can satisfy future NH3 regulations through the NH3 reduction technology of gasoline engine vehicles.

In addition, by preemptively securing NH3 reduction technology, it can be expected to improve the quality of environmentally friendly products and improve customer satisfaction.

The embodiment of the present invention is not implemented only through the apparatus and/or method described above, but a program for realizing a function corresponding to the configuration of the embodiment of the present invention, a recording medium in which the program is recorded, etc. Also, such an implementation can be easily implemented by an expert in the technical field to which the present invention pertains from the description of the above-described embodiment.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improved forms of the present invention are also provided by those skilled in the art using the basic concept of the present invention as defined in the following claims. is within the scope of the right.

100: exhaust gas reduction system 110: engine
120: exhaust line 130: warm-up catalytic converter (WCC)
140: underfloor catalytic converter (UCC) 145 NH3 reduction catalyst
150: control unit

Claims (15)

WCC (Warm up Catalytic Converter) installed on the exhaust line of the engine to purify the exhaust gas;
a first lambda sensor and a second lambda sensor respectively disposed at the front end and rear end of the WCC to sense a lambda value of the exhaust gas passing through the exhaust line;
UCC (Under floor Catalytic Converter) installed at the rear of the WCC to reduce harmful substances contained in the exhaust gas;
an NH3 reduction catalyst configured at the rear end of the UCC to store oxygen;
a temperature sensor for measuring a catalyst temperature of the NH3 reduction catalyst; and
Receives sensing information from various sensors to control the engine's lambda, stores oxygen supplied in the operating condition in which oxygen is increased in the NH3 reduction catalyst, and stores ammonia (NH3) generated during rich operating conditions to the NH3 a control unit that oxidizes using oxygen stored in the reduction catalyst;
Exhaust gas reduction system comprising a. According to claim 1,
The WCC is
Exhaust gas reduction system including a three-way catalyst (Three Way Catalyst converter) for reducing harmful substances of HC, NOx, CO, PM, PN contained in the exhaust gas by catalytic action. 3. The method of claim 1 or 2,
The first lambda sensor detects a first lambda value (λ1) of the exhaust gas discharged from the engine and flowing into the WCC and transmits it to the control unit,
The second lambda sensor detects a second lambda value (λ2) of the exhaust gas discharged from the WCC and transmits it to the control unit. According to claim 1,
The NH3 reduction catalyst is
An exhaust gas reduction system comprising a catalyst device that stores oxygen supplied during fuel cut control, and stores excess oxygen even under the oxygen-lean rich condition to reduce NH3. 5. The method of claim 1 or 4,
The NH3 reduction catalyst is
Exhaust gas reduction system including a high OSC (Oxygen Storage Capacity) characteristic increased compared to other catalysts for the NH3 reduction performance. 6. The method of claim 5,
The NH3 reduction catalyst is
An exhaust gas reduction system comprising an oxygen storage material (CeO2) in 30% or more of the catalyst coating amount or an excess oxygen storage material of 30 g/L or more for the high OSC characteristics. According to claim 1,
the control unit
An exhaust gas reduction system for controlling lambda in a range in which the amount of residual oxygen of the NH3 reduction catalyst is not exhausted. 8. The method of claim 1 or 7,
the control unit
An exhaust gas reduction system for performing at least one of a lambda control for reducing a rich operation time or reducing a rich degree according to the amount of residual oxygen of the NH3 reduction catalyst under a rich operation condition. In the method of controlling the exhaust gas reduction system of the control unit that purifies the exhaust gas using a WCC (Warm up Catalytic Converter), UCC (Under floor Catalytic Converter) and NH3 reduction catalyst configured at the rear end of the UCC installed on the exhaust line of the engine,
a) collecting a first lambda value (λ1) and a second lambda value (λ2) of the exhaust gas from a first lambda sensor and a second lambda sensor respectively installed at the front end and the rear end of the WCC;
b) detecting an oxygen exhaustion condition of the NH3 reduction catalyst in which the first lambda value (λ1) is 1 or less and the second lambda value (λ2) is equal to or greater than a predetermined value;
c) calculating a reducing agent supply amount (R1) according to the exhaust flow rate and the first lambda value (λ1);
d) calculating the residual oxygen amount (S1) of the NH3 reduction catalyst with reference to an oxygen storage amount map (OSC MAP) based on the exhaust flow rate and catalyst temperature; and
e) when the value obtained by dividing the reducing agent supply amount (R1) by the residual oxygen amount (S1) satisfies the condition that is less than a constant value (a) of one or more;
Exhaust gas reduction system control method comprising a. 10. The method of claim 9,
Before step a),
The method of controlling an exhaust gas reduction system further comprising the step of storing oxygen supplied in the operating condition in which oxygen is increased in the NH3 reduction catalyst. 10. The method of claim 9,
Step b) is,
and oxidizing ammonia (NH3) generated under rich operating conditions using oxygen stored in the NH3 reduction catalyst. 10. The method of claim 9,
Step c) is,
deriving concentrations of CO, CO2, and H2 according to the first lambda value (λ1);
calculating the amount of reducing agent over time by multiplying the exhaust flow rate by the value obtained by multiplying the concentration of the reducing agent (i) and the reducing agent (i) density to be input according to the concentrations of the CO, CO2, and H2; and
calculating the reducing agent supply amount (R1) by accumulating the amount of reducing agent over time;
Exhaust gas reduction system control method comprising a. 10. The method of claim 9,
Step d) is,
and calculating the amount of residual oxygen (S1) by subtracting the amount of oxygen reacted with the reducing agent from the amount of oxygen of the NH3 reduction catalyst derived by the OSC MAP. 14. The method according to any one of claims 9 to 13,
Step e) is,
and performing NH3 reduction lambda control to a value higher than the first lambda value (λ1) by multiplying the first lambda value (λ1) by a constant value (b) of 1 or more to reduce the amount of fuel and increase the amount of air A method of controlling a gas abatement system. 15. The method of claim 14,
Step e) is,
The exhaust gas reduction system control method further comprising the step of controlling the NH3 reduction lambda control by reducing the rich operation time compared to the basic rich operation time.

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