KR101241208B1 - Exhaust gas post processing method and system performing this - Google Patents

Exhaust gas post processing method and system performing this Download PDF

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KR101241208B1
KR101241208B1 KR1020100092647A KR20100092647A KR101241208B1 KR 101241208 B1 KR101241208 B1 KR 101241208B1 KR 1020100092647 A KR1020100092647 A KR 1020100092647A KR 20100092647 A KR20100092647 A KR 20100092647A KR 101241208 B1 KR101241208 B1 KR 101241208B1
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reduction catalyst
selective reduction
hydrocarbon
amount
exhaust gas
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KR20120030846A (en
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이상민
박지원
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현대자동차주식회사
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • F01N2610/146—Control thereof, e.g. control of injectors or injection valves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

본 발명의 실시예에 따른 배기가스 후처리 방법은, 엔진의 가동조건에 따라서 탄화수소와 질소산화물의 설정된 배출양을 선택하는 단계, 상기 선택적환원촉매의 전후단 온도차를 감지하는 단계, 상기 선택적환원촉매의 설정된 효율값과 상기 전후단 온도차를 이용하여 상기 선택적환원촉매로 유입되는 탄화수소의 실제유입량을 연산하는 단계, 및 상기 탄화수소의 실제유입량과 상기 질소산화물의 설정된 배출양의 비율이 설정된 값 미만이면, 후분사를 실시하여 상기 선택적환원촉매로 유입되는 탄화수소의 양을 늘리는 단계를 포함한다.
따라서, 선택적환원촉매로 유입되는 탄화수소의 양을 보다 정밀하게 예측함으로써 배기가스 내의 탄화수소양을 보다 정밀하게 제어할 수 있다. 따라서, 엔진의 후분사로 인한 연료의 소모를 저감시킬 수 있다.Exhaust gas after-treatment method according to an embodiment of the present invention, selecting the set amount of hydrocarbon and nitrogen oxide according to the operating conditions of the engine, detecting the temperature difference before and after the selective reduction catalyst, the selective reduction catalyst Calculating the actual inflow amount of hydrocarbons flowing into the selective reduction catalyst using the set efficiency value and the front and rear end temperature difference, and if the ratio of the actual inflow amount of the hydrocarbons and the set discharge amount of the nitrogen oxide is less than the set value, the after injection The step of increasing the amount of hydrocarbon introduced into the selective reduction catalyst.
Therefore, it is possible to more precisely control the amount of hydrocarbons in the exhaust gas by more accurately predicting the amount of hydrocarbons flowing into the selective reduction catalyst. Therefore, it is possible to reduce the consumption of fuel due to post injection of the engine.

Description

배기가스 후처리 방법 및 이를 수행하는 시스템{EXHAUST GAS POST PROCESSING METHOD AND SYSTEM PERFORMING THIS}Exhaust gas aftertreatment method and system for performing the same {EXHAUST GAS POST PROCESSING METHOD AND SYSTEM PERFORMING THIS}

본 발명은 배기가스 후처리 방법 및 이를 수행하는 시스템에 관한 것으로서, 보다 상세하게는 배기가스에 포함된 탄화수소를 이용하여 질소산화물을 정화하는 배기가스 후처리 방법 및 이를 수행하는 시스템에 관한 것이다.The present invention relates to an exhaust gas aftertreatment method and a system for performing the same, and more particularly, to an exhaust gas aftertreatment method for purifying nitrogen oxide using a hydrocarbon contained in exhaust gas and a system for performing the same.

일반적으로, 엔진에서 배출되는 배기가스에는 입자상물질과 질소산화물과 같은 유해물질을 포함하고 있으며, 질소산화물은 선택적환원촉매(Selective Catalyst Reduction: SCR)에 의해서 저감된다.In general, exhaust gas emitted from an engine contains particulate matter and harmful substances such as nitrogen oxides, and nitrogen oxides are reduced by a selective catalyst reduction (SCR).

패시브 탄화수소 선택적환원촉매(passive HC-SCR)은 UREA-SCR이나 LNT(Lean NOx Trap)과 비교하여 NOx를 정화하는데 낮은 효율을 갖는다. Passive HC-SCR has a lower efficiency for purifying NOx compared to UREA-SCR or LNT (Lean NOx Trap).

HC-SCR은 배기가스에 포함된 탄화수소(HC)를 이용하여 일정한 온도에서 질소산화물(NOx)를 저감시키는데, HC와 NOx의 비와 온도가 중요한 변수이다.HC-SCR reduces the nitrogen oxides (NOx) at a constant temperature by using hydrocarbons (HC) contained in the exhaust gas, and the ratio and temperature of HC and NOx are important variables.

한편, 배기가스의 온도가 낮은 경우에는 상기 선택적환원촉매(HC-SCR)의 질소산화물 정화기능이 떨어져 배기가스에 포함된 탄화수소가 남게 되고, 배기가스의 온도가 설정된 범위 일 경우에는 상기 선택적환원촉매(HC-SCR)의 질소산화물 정화기능이 높아져 배기가스에 포함된 탄화수소가 부족하게 된다.On the other hand, when the temperature of the exhaust gas is low, the nitrogen oxide purification function of the selective reduction catalyst (HC-SCR) is deteriorated and hydrocarbons contained in the exhaust gas remain, and when the temperature of the exhaust gas is within the set range, the selective reduction catalyst The HC-SCR's ability to purify nitrogen oxides is high, resulting in a lack of hydrocarbons in the exhaust gases.

이와 같이, 배기가스에 포함된 탄화수소가 부족하게 되면, 엔진에서 후분사를 통해서 연료를 추가 분사하여 탄화수소의 양을 늘리게 되는데, 연료의 소모가 늘어나는 문제점이 있다.As such, when the hydrocarbon contained in the exhaust gas is insufficient, the amount of hydrocarbon is increased by additionally injecting fuel through post-injection in the engine, but there is a problem in that fuel consumption is increased.

따라서, 본 발명은 배기가스에 포함된 탄화수소의 양을 실질적으로 정확하게 감지하고, 이렇게 감지된 탄화수소와 질소산화물의 비에 따라서 후분사를 실시함으로써 연료의 소모를 저감시키는 배기가스 후처리 제어방법 및 이를 수행하는 시스템을 제공하는 것이다.Accordingly, the present invention provides a method for controlling exhaust gas after-treatment that reduces fuel consumption by substantially accurately detecting the amount of hydrocarbons contained in exhaust gas and performing post-injection according to the ratio of the detected hydrocarbons and nitrogen oxides. It is to provide a system to perform.

본 발명에 따른 배기가스 후처리 방법은, 엔진의 가동조건에 따라서 탄화수소와 질소산화물의 설정된 배출양을 선택하는 단계, 주행거리 또는 엔진의 가동시간에 따라서 선택적환원촉매의 설정된 효율값을 선택하는 단계, 상기 선택적환원촉매의 전후단 온도차를 감지하는 단계, 상기 선택적환원촉매의 설정된 효율값과 상기 전후단 온도차를 이용하여 상기 선택적환원촉매로 유입되는 탄화수소의 실제유입량을 연산하는 단계, 및 상기 탄화수소의 실제유입량과 상기 질소산화물의 설정된 배출양의 비율이 설정된 값 미만이면, 후분사를 실시하여 상기 선택적환원촉매로 유입되는 탄화수소의 양을 늘리는 단계를 포함한다.Exhaust gas after-treatment method according to the invention, the step of selecting the set amount of hydrocarbon and nitrogen oxides according to the operating conditions of the engine, the step of selecting the set efficiency value of the selective reduction catalyst according to the running distance or the engine running time, Detecting a temperature difference between the front and rear ends of the selective reduction catalyst, calculating an actual inflow amount of hydrocarbon introduced into the selective reduction catalyst using the set efficiency value of the selective reduction catalyst and the front and rear end temperature difference, and the actual amount of the hydrocarbon If the ratio between the inflow amount and the set discharge amount of the nitrogen oxide is less than the set value, and performing a post-injection to increase the amount of hydrocarbon flowing into the selective reduction catalyst.

상기 탄화수소의 실제유입량과 상기 질소산화물의 설정된 배출양의 비율이 설정된 값 이상이면, 후분사를 실시하지 않는다.If the ratio of the actual inflow amount of the hydrocarbon and the set discharge amount of the nitrogen oxide is more than the set value, the post-injection is not performed.

상기 선택적환원촉매의 전후단 온도차에 의한 실제 효율값을 연산하는 단계, 및 주행거리 또는 엔진의 가동시간에 따라서 선택된 상기 선택적환원촉매의 설정된 효율값에서 상기 선택적환원촉매의 전후단 온도차에 의한 실제 효율값을 뺀값이 설정값을 초과하면, 상기 선택적환원촉매가 비정상적으로 작동된다는 이상신호를 발생시키는 단계를 포함한다.Calculating an actual efficiency value based on the temperature difference between the front and rear ends of the selective reduction catalyst, and the actual efficiency according to the front and rear temperature difference of the selective reduction catalyst at a set efficiency value of the selective reduction catalyst selected according to the traveling distance or the engine running time. Generating a fault signal that the selective reduction catalyst is abnormally operated when the value obtained by subtracting the value exceeds the set value.

상기 선택적환원촉매의 전단부 온도가 설정된 온도로 일정시간 동안 유지될 때, 상기 이상신호를 발생시키는 단계를 수행한다.When the front end temperature of the selective reduction catalyst is maintained at a predetermined temperature for a predetermined time, generating the abnormal signal.

엔진에서 배출되는 배기가스에 포함된 탄화수소를 흡착하거나 탈착하는 탄화수소트랩, 상기 탄화수소트랩의 후단부에 장착되어 배기가스에 포함된 탄화수소를 이용하여 질소산화물을 제거하는 선택적환원촉매, 및 운전조건에 따라서 상기 배기라인으로 후분사를 실시하기 위해서 설정된 프로그램을 실행하는 제어부를 포함하고, 상기 설정된 프로그램은, 상기 배기가스 후처리 방법을 수행하기 위한 명령을 포함한다.A hydrocarbon trap for adsorbing or desorbing hydrocarbons contained in the exhaust gas discharged from the engine, a selective reduction catalyst which is installed at the rear end of the hydrocarbon trap to remove nitrogen oxides using hydrocarbons contained in the exhaust gas, and operating conditions And a control unit that executes a set program for performing post injection into the exhaust line, wherein the set program includes instructions for performing the exhaust gas post-treatment method.

앞에서 기재된 바와 같이 본 발명에 따른 배기가스 후처리 방법에서, 선택적환원촉매로 유입되는 탄화수소의 양을 보다 정밀하게 예측함으로써 배기가스 내의 탄화수소양을 보다 정밀하게 제어할 수 있다. 따라서, 엔진의 후분사로 인한 연료의 소모를 저감시킬 수 있다.As described above, in the exhaust gas aftertreatment method according to the present invention, it is possible to more precisely control the amount of hydrocarbons in the exhaust gas by more accurately predicting the amount of hydrocarbons flowing into the selective reduction catalyst. Therefore, it is possible to reduce the consumption of fuel due to post injection of the engine.

도 1은 본 발명의 실시예에 따른 배기가스 후처리 시스템의 개략적인 구성도이다.
도 2는 본 발명의 실시예에 따른 배기가스 후처리 제어방법을 수행하기 위한 플로우차트이다.
도 3은 본 발명의 실시예에 따른 선택적환원촉매(HC-SCR)의 전후단 온도차와 유입량(농도)에 따른 관계를 나타내는 그래프이다.1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.
2 is a flowchart for performing the exhaust gas after-treatment control method according to an embodiment of the present invention.
Figure 3 is a graph showing the relationship between the front and rear temperature difference and the inflow (concentration) of the selective reduction catalyst (HC-SCR) according to an embodiment of the present invention.

이하, 본 발명의 바람직한 실시예를 첨부한 도면에 의거하여 상세하게 설명하면 다음과 같다.Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도 1은 본 발명의 실시예에 따른 배기가스 후처리 시스템의 개략적인 구성도이다.1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.

도 1을 참조하면, 배기가스 후처리 시스템은 엔진(100), 탄화수소트랩(110), 선택적환원촉매(120), 제1온도센서(130), 제2온도센서(140), 및 제어부(150)를 포함한다.Referring to FIG. 1, the exhaust gas aftertreatment system includes an engine 100, a hydrocarbon trap 110, a selective reduction catalyst 120, a first temperature sensor 130, a second temperature sensor 140, and a controller 150. ).

상기 탄화수소트랩(110)은 HC-trap이라고도 불리우고, 상기 선택적환원촉매(120)는 탄화수소를 이용하기 때문에 HC-SCR이라고도 불리운다.The hydrocarbon trap 110 is also called HC-trap, and the selective reduction catalyst 120 is also called HC-SCR because it uses a hydrocarbon.

상기 엔진(100)는 탄화수소, 질소산화물을 포함하는 배기가스를 배출하고, 상기 탄화수소트랩(110)은 저온조건(섭씨 180도 이하)에서 배기가스에 포함된 탄화수소를 저장(trap)하고 있다가, 고온조건에서 저장된 탄화수소를 배출한다.The engine 100 exhausts exhaust gas containing hydrocarbons and nitrogen oxides, and the hydrocarbon trap 110 traps hydrocarbons contained in the exhaust gas under low temperature conditions (180 degrees Celsius or less). Emissions of stored hydrocarbons at high temperatures.

상기 선택적환원촉매(120)는 배기가스에 포함된 탄화수소를 이용하여 질소산화물을 저감시키며, 탄화수소와 질소산화물의 비와 온도에 따라서 그 저감량(정화량)이 변화되며, 섭씨 약 200도 이상에서 저감량이 높고 200도 미만에서 저감량은 작다. The selective reduction catalyst 120 reduces nitrogen oxides using hydrocarbons contained in the exhaust gas, and the reduction amount (purification amount) is changed according to the ratio and temperature of hydrocarbons and nitrogen oxides, and the reduction amount is about 200 degrees Celsius or more. It is high and the reduction is small at less than 200 degrees.

따라서, 200도 이상에서는 상기 선택적환원촉매(120)는 상기 질소산화물을 저감시키기 위한 탄화수소가 부족하기 쉽고, 200도 미만에서는 상기 선택적환원촉매는 상기 질소산화물을 저감시키기 위한 탄화수소가 납기 쉽다. Therefore, at 200 degrees or more, the selective reduction catalyst 120 is likely to run out of hydrocarbons for reducing the nitrogen oxides, and at less than 200 degrees, the selective reduction catalysts are easy to deliver hydrocarbons for reducing the nitrogen oxides.

그러나, 본 발명의 실시예에서는, 상기 탄화수소트랩(110)은 탄화수소가 충분한 저온에서 탄화수소를 포집하고, 탄화수소가 부족한 고온에서 탄화수소를 배출하여 상기 선택적환원촉매의 질소산화물저감을 돕는다.However, in the embodiment of the present invention, the hydrocarbon trap 110 captures the hydrocarbon at a low temperature sufficient for the hydrocarbon and discharges the hydrocarbon at the high temperature at which the hydrocarbon is insufficient to help reduce the nitrogen oxide of the selective reduction catalyst.

상기 선택적환원촉매(120)의 전단부와 후단부에 각각 상기 제1온도센서(130)와 상기 제2온도센서(140)가 장착되고, 그 온도신호를 상기 제어부(150)로 전달한다. 아울러, 상기 제어부(150)는 상기 엔진(100)의 회전수, 연료분사량, 및 토크 등을 감지하여 엔진의 운전조건을 감지한다.The first temperature sensor 130 and the second temperature sensor 140 are mounted at the front and rear ends of the selective reduction catalyst 120, respectively, and transmit the temperature signal to the controller 150. In addition, the controller 150 detects the engine operating condition by detecting the rotation speed, the fuel injection amount, and the torque of the engine 100.

본 발명의 실시예에서, 배기가스의 온도가 섭씨 180도 내지 250도의 범위에서 탄화수소(HC)와 질소산화물(NOx)의 비가 5:1이상 경우, 별도의 엔진 후분사 없이 탄화수소(HC)의 공급이 필요 없으며, 배기가스가 저온이거나 탄화수소의 비율이 5 미만일 경우 엔진 후분사를 통해서 탄화수소를 증가시켜야 한다.In an embodiment of the present invention, when the ratio of the hydrocarbon (HC) and the nitrogen oxides (NOx) in the range of 180 to 250 degrees Celsius is 5: 1 or more, supply of hydrocarbons (HC) without a separate engine after injection This is not necessary, and if the exhaust gas is cold or the proportion of hydrocarbons is less than 5, the hydrocarbons have to be increased through post injection.

본 발명의 실시예에서, 상기 탄화수소트랩(110)은 저온조건에서 탄화수소를 흡착하였다가, 섭씨 180도 이상에서 배출하여 탄화수소의 비율을 증가시켜 상기 선택적환원촉매(120)의 질소산화물정화율을 높여, 후분사로 인한 연료소비를 절약한다.In the embodiment of the present invention, the hydrocarbon trap 110 is adsorbed hydrocarbon at low temperature conditions, discharged at 180 degrees Celsius or more to increase the proportion of hydrocarbons to increase the nitrogen oxide purification rate of the selective reduction catalyst 120 This saves fuel consumption due to post injection.

상기 엔진(100)에서 배출되는 탄화수소와 질소산화물의 배출량은 맵데이터와 같이 미리 설정된 값이며, 상기 제어부(150)는 상기 엔진(100)의 가동조건에 따른 설정된 탄화수소의 설정된 배출량과 질소산화물의 설정된 배출량을 선택한다.Emissions of hydrocarbons and nitrogen oxides discharged from the engine 100 are preset values as map data, and the controller 150 sets the set emissions of hydrocarbons and nitrogen oxides according to operating conditions of the engine 100. Select the emissions.

한편, 상기 선택적환원촉매(120)로 유입되는 실제로 탄화수소와 질소산화물의 비가 5:1이상인 경우에 후분사가 필요없고, 탄화수소의 비율이 5미만일 경우 후분사를 통해서 탄화수소의 양을 늘린다. On the other hand, after the injection of the selective reduction catalyst 120 actually does not need after injection when the ratio of the hydrocarbon and nitrogen oxide is 5: 1 or more, if the ratio of the hydrocarbon is less than 5 to increase the amount of hydrocarbon through the post injection.

따라서, 상기 탄화수소트랩(110)에 의해서 포집되거나 배출되는 탄화수소에 의해서 상기 선택적환원촉매(120)로 유입되는 실제유입량을 연산할 필요가 있으며, 탄화수소의 실제 유입량을 감지할 수 있는 센서는 고가이고 반응이 늦으므로 현실적으로 이를 직접적으로 감지하는 것은 불가능하다.Therefore, it is necessary to calculate the actual inflow amount flowing into the selective reduction catalyst 120 by the hydrocarbon trapped or discharged by the hydrocarbon trap 110, the sensor that can detect the actual inflow of hydrocarbon is expensive and reactive This is late and in reality it is impossible to detect this directly.

본 발명의 실시예에서는, 상기 제어부(150)는 상기 엔진(100)의 가동시간과 차량의 주행거리에 따른 미리 설정된 상기 선택적환원촉매(120)의 설정된 효율을 맵데이터로부터 선택하고, 상기 선택적환원촉매(120)의 전후단 온도를 감지하고, 그 차이값을 연산한다.In an embodiment of the present invention, the control unit 150 selects a predetermined efficiency of the selective reduction catalyst 120 set in advance according to the operating time of the engine 100 and the driving distance of the vehicle from the map data, and the selective reduction The front and rear temperature of the catalyst 120 is sensed and the difference value is calculated.

도 3은 본 발명의 실시예에 따른 선택적환원촉매(HC-SCR)의 전후단 온도차와 유입량(농도)에 따른 관계를 나타내는 그래프이다.Figure 3 is a graph showing the relationship between the front and rear temperature difference and the inflow (concentration) of the selective reduction catalyst (HC-SCR) according to an embodiment of the present invention.

도 3을 참조하면, 가로축은 탄화수소의 유입량을 나타내고, 세로축은 상기 선택적환원촉매(120)의 전후단 온도차를 나타낸다.Referring to FIG. 3, the horizontal axis represents the inflow of hydrocarbons, and the vertical axis represents the temperature difference between the front and rear ends of the selective reduction catalyst 120.

상기 제어부(150)는, 상기 선택적환원촉매(120)의 전후단 온도차에 따른 탄화수소의 유입량을 연산하되, 상기 선택적환원촉매(120)의 설정된 효율을 이용하여, 실질적으로 상기 선택적환원촉매(120)로 유입되는 탄화수소의 실제 유입양을 연산한다.The controller 150 calculates the inflow of hydrocarbons according to the temperature difference between the front and rear ends of the selective reduction catalyst 120, and by using the set efficiency of the selective reduction catalyst 120, the selective reduction catalyst 120 is substantially used. Calculate the actual amount of hydrocarbon introduced into the furnace.

상기 제어부(150)는 상기 선택적환원촉매(120)로 유입되는 탄화수소의 실제유입량과 엔진(100)에서 배출되는 질소산화물의 설정된 배출량을 비교하여, 그 비율이 5:1 (탄화수소:질소산화물) 미만이면, 상기 엔진에서 설정된 양의 후분사를 실시한다. 또는, 탄화수소의 비율이 5 이상이면, 후분사를 실시하지 않는다.The controller 150 compares the actual inflow of hydrocarbons flowing into the selective reduction catalyst 120 with the set emissions of nitrogen oxides discharged from the engine 100, and the ratio is less than 5: 1 (hydrocarbon: nitrogen oxides). After that, the amount of post-injection set in the engine is performed. Or, if the ratio of hydrocarbon is 5 or more, post-injection will not be performed.

아울러, 상기 제어부(150)는 상기 선택적환원촉매(120)의 전후단 온도차와 탄화수소의 실제유입량을 이용하여 실제 효율을 연산하고, 주행거리나 엔진의 가동시간에 따른 설정된 효율을 비교하여, 그 차이값이 설정된 수치 이상일 경우에는 이상신호를 발생시켜, 자가진단(OBD: On Boar Diagnosis)을 실시한다.In addition, the controller 150 calculates the actual efficiency by using the front and rear temperature difference of the selective reduction catalyst 120 and the actual inflow amount of hydrocarbon, and compares the set efficiency according to the mileage or the engine running time, the difference If the value is over the set value, an abnormal signal is generated and self diagnosis (OBD: On Boar Diagnosis) is performed.

도 2는 본 발명의 실시예에 따른 배기가스 후처리 제어방법을 수행하기 위한 플로우차트이다.2 is a flowchart for performing the exhaust gas after-treatment control method according to an embodiment of the present invention.

도 2를 참조하면, S200에서 엔진이 가동되어 제어가 시작되고, S210에서 냉각수온이 설정된 값(a) 보다 큰지 판단한다. 여기서, 냉각수온이 설정된 값보다 크다는 것은 엔진이 웜업되고 배기가스의 온도가 상승한 상태를 의미한다.Referring to FIG. 2, the engine is operated at S200 to start control, and at S210, it is determined whether the coolant temperature is greater than a set value (a). Here, when the cooling water temperature is greater than the set value means that the engine is warmed up and the temperature of the exhaust gas is increased.

S220에서, 상기 엔진(100)의 알피엠, 연료분사량, 및 토크에 따른 탄화수소와 질소산화물의 설정된 배출량을 맵데이터 등으로부터 선택한다. In S220, the set emissions of hydrocarbons and nitrogen oxides according to the LP, the fuel injection amount, and the torque of the engine 100 are selected from the map data.

S230에서, 상기 선택적환원촉매(120)의 전후단온도를 감지한다. 여기서, 상기 선택적환원촉매(120)의 전단부 온도는 배기가스온도 맵에 따라서 미리 설정된 값일 수 있고, 상기 선택적환원촉매(120)의 후단부 온도는 상기 제2온도센서로부터 감지한다.In S230, the front and rear temperature of the selective reduction catalyst 120 is sensed. Here, the front end temperature of the selective reduction catalyst 120 may be a preset value according to the exhaust gas temperature map, and the rear end temperature of the selective reduction catalyst 120 is detected by the second temperature sensor.

S240에서, 상기 엔진(100)의 가동시간과 차량의 주행거리를 감지(선택)하고, S250에서, 상기 엔진(100)의 가동시간과 주행거리에 따른 미리 설정된 상기 선택적환원촉매(120)의 효율을 선택한다.In operation S240, the operating time of the engine 100 and the driving distance of the vehicle are sensed (selected), and in operation S250, the efficiency of the predetermined selective reduction catalyst 120 preset according to the operation time and the driving distance of the engine 100. Select.

S260에서, 설정된 효율(efficiency)과 상기 선택적환원촉매(120)의 전후단 온도차에 따라서 상기 선택적환원촉매(120)로 유입되는 탄화수소의 실제유입량을 연산한다.In S260, the actual amount of hydrocarbon introduced into the selective reduction catalyst 120 is calculated according to the set efficiency and the temperature difference between the front and rear ends of the selective reduction catalyst 120.

S270에서, 상기 S220에서 선택된 질소산화물의 설정된 배출량과 상기 S260에서 연산된 탄화수소의 실제유입량의 비율을 비교하여, 상기 탄화수소의 실제유입량의 비가 5미만이면, S280에서 결정된 후분사량에 따라서 후분사를 실시하여 탄화수소의 양을 늘린다.In S270, the ratio of the set emissions of the nitrogen oxide selected in S220 and the actual inflow amount of the hydrocarbon calculated in S260 is compared, and if the ratio of the actual inflow amount of the hydrocarbon is less than 5, post-injection is performed according to the post injection amount determined in S280. To increase the amount of hydrocarbons.

상기 S270에서 상기 탄화수소의 실제 유입량의 비가 5 이상이면, S290에서 상기 엔진(100)은 후분사 없이 정상적으로 작동된다. If the ratio of the actual inflow rate of the hydrocarbon in S270 is 5 or more, in S290 the engine 100 operates normally without post injection.

아울러, S292에서, 상기 선택적환원촉매(120)의 전후단 온도차에 따른 상기 선택적환원촉매(120)의 실제효율과 상기 S250에서 선택된 상기 선택적환원촉매(120)의 설정된효율(e)과의 차이가 설정된 값(0.2 또는 20%) 이상이면, S294에서 이상 신호를 발생시킬 수 있다.In addition, in S292, the difference between the actual efficiency of the selective reduction catalyst 120 and the set efficiency (e) of the selective reduction catalyst 120 selected in S250 according to the front and rear temperature difference of the selective reduction catalyst 120 If the set value (0.2 or 20%) or more, the abnormal signal can be generated in S294.

상기 S292는 상기 선택적환원촉매(120)의 상태가 일정한 상태에 수행되는 것이 바람직하다. 즉, 상기 선택적환원촉매(120)가 일정한 온도로 일정한 시간 동안 유지될 때 수행되는 것이 바람직하다.S292 is preferably carried out in a state of the selective reduction catalyst 120. That is, the selective reduction catalyst 120 is preferably carried out when maintained at a constant temperature for a certain time.

본 발명의 실시예에 따른 상기 탄화수소트랩(HC-trap)은 제올라이트, Si, Al로 구성된 다공성 물질로, 고온(또는 물) 조건에서 탄화수소의 흡착성능이 떨어지고 그 반대조건에서는 탄화수소의 흡착성능이 향상된다.The hydrocarbon trap (HC-trap) according to an embodiment of the present invention is a porous material composed of zeolite, Si, and Al, and the adsorption performance of hydrocarbons is decreased at high temperature (or water) conditions, and the adsorption performance of hydrocarbons is improved under the opposite conditions. do.

이상으로 본 발명에 관한 바람직한 실시예를 설명하였으나, 본 발명은 상기 실시예에 한정되지 아니하며, 본 발명의 실시예로부터 당해 발명이 속하는 기술분야에서 통상의 지식을 가진 자에 의한 용이하게 변경되어 균등하다고 인정되는 범위의 모든 변경을 포함한다.While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

100: 엔진
110: 탄화수소트랩
120: 선택적환원촉매
130: 제1온도센서
140: 제2온도센서
150: 제어부100: engine
110: hydrocarbon trap
120: selective reduction catalyst
130: first temperature sensor
140: second temperature sensor
150:

Claims (5)

엔진의 가동조건에 따라서 탄화수소와 질소산화물의 설정된 배출양을 선택하는 단계;
선택적환원촉매의 전후단 온도차를 감지하는 단계;
상기 선택적환원촉매의 설정된 효율값과 상기 전후단 온도차를 이용하여 상기 선택적환원촉매로 유입되는 탄화수소의 실제유입량을 연산하는 단계;
상기 탄화수소의 실제유입량과 상기 질소산화물의 설정된 배출양의 비율이 설정된 값 이상이면, 후분사를 실시하지 않되, 상기 탄화수소의 실제유입량과 상기 질소산화물의 설정된 배출양의 비율이 설정된 값 미만이면, 후분사를 실시하여 상기 선택적환원촉매로 유입되는 탄화수소의 양을 늘리는 단계;
선택적환원촉매의 전후단 온도차에 의한 실제 효율값을 연산하는 단계; 및
주행거리 또는 엔진의 가동시간에 따라서 선택된 상기 선택적환원촉매의 설정된 효율값에서 선택적환원촉매의 전후단 온도차에 의한 실제 효율값을 뺀값이 설정값을 초과하면, 상기 선택적환원촉매가 비정상적으로 작동된다는 이상신호를 발생시키는 단계; 를 더 포함하는 배기가스 후처리 방법.Selecting a set discharge amount of hydrocarbons and nitrogen oxides according to the operating conditions of the engine;
Detecting a temperature difference before and after the selective reduction catalyst;
Calculating an actual inflow amount of hydrocarbon introduced into the selective reduction catalyst using the set efficiency value of the selective reduction catalyst and the front and rear end temperature differences;
If the ratio of the actual inflow amount of the hydrocarbon and the set discharge amount of the nitrogen oxide is greater than or equal to the set value, no post-injection is performed, but if the ratio of the actual inflow amount of the hydrocarbon and the set discharge amount of the nitrogen oxide is less than the set value, the post injection Increasing the amount of hydrocarbon introduced into the selective reduction catalyst;
Calculating an actual efficiency value based on a temperature difference before and after the selective reduction catalyst; And
If the value of the selected reduction catalyst selected according to the mileage or the engine running time minus the actual efficiency value due to the temperature difference between the front and rear ends of the selective reduction catalyst exceeds the set value, the selective reduction catalyst is abnormally operated. Generating a signal; Exhaust gas after-treatment method further comprising. 삭제delete 삭제delete 제1항에서,
상기 선택적환원촉매의 전단부 온도가 설정된 온도로 일정시간 동안 유지될 때, 상기 이상신호를 발생시키는 단계를 수행하는 것을 특징으로 하는 배기가스 후처리 방법.In claim 1,
And generating the abnormal signal when the front end temperature of the selective reduction catalyst is maintained at a predetermined temperature for a predetermined time. 엔진에서 배출되는 배기가스에 포함된 탄화수소를 흡착하거나 탈착하는 탄화수소트랩;
상기 탄화수소트랩의 후단부에 장착되어 배기가스에 포함된 탄화수소를 이용하여 질소산화물을 제거하는 선택적환원촉매; 및
운전조건에 따라서 배기라인으로 후분사를 실시하기 위해서 설정된 프로그램을 실행하는 제어부; 를 포함하고,
상기 설정된 프로그램은, 제1항 및 제4항 중 어느 한 항의 방법을 수행하기 위한 명령을 포함하는 것을 특징으로 하는 배기가스 후처리 시스템.A hydrocarbon trap for absorbing or desorbing hydrocarbons contained in the exhaust gas discharged from the engine;
A selective reduction catalyst mounted on a rear end of the hydrocarbon trap to remove nitrogen oxides using a hydrocarbon contained in exhaust gas; And
A control unit which executes a set program for performing post-injection into the exhaust line according to the operating conditions; Including,
And said set program comprises instructions for performing the method of any one of claims 1 and 4.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11229850A (en) * 1998-02-13 1999-08-24 Nissan Motor Co Ltd Exhaust purifier of diesel engine

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11229850A (en) * 1998-02-13 1999-08-24 Nissan Motor Co Ltd Exhaust purifier of diesel engine

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