KR100427294B1 - A method of determining air fuel ratio in gasoline direct injection engine - Google Patents

A method of determining air fuel ratio in gasoline direct injection engine Download PDF

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KR100427294B1
KR100427294B1 KR10-2000-0087019A KR20000087019A KR100427294B1 KR 100427294 B1 KR100427294 B1 KR 100427294B1 KR 20000087019 A KR20000087019 A KR 20000087019A KR 100427294 B1 KR100427294 B1 KR 100427294B1
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operation mode
fuel ratio
lean
direct injection
air
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KR10-2000-0087019A
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KR20020058887A (en
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김원태
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현대자동차주식회사
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3818—Common rail control systems for petrol engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0404—Throttle position

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

본 발명은 가솔린 직접 분사 엔진(gasoline direct injection; GDI)에 관한 것으로서, 더욱 상세하게는 가솔린 직접 분사 엔진의 전자 제어 시스템(electronic management system; EMS)에서 공연비 제어에 관한 것이다.The present invention relates to a gasoline direct injection engine (GDI), and more particularly to an air-fuel ratio control in an electronic management system (EMS) of a gasoline direct injection engine.

본 발명에 따르면 가솔린 직접 분사 엔진에 적용되는 3가지 운전 모드에서 단일의 산소 센서에서 검출되는 신호를 적용하여 각 운전모드에서의 안정된 공연비 제어를 수행한다.According to the present invention, stable air-fuel ratio control is performed in each operation mode by applying a signal detected by a single oxygen sensor in three operation modes applied to a gasoline direct injection engine.

Description

가솔린 직접 분사 엔진의 공연비 상태 판정방법{A METHOD OF DETERMINING AIR FUEL RATIO IN GASOLINE DIRECT INJECTION ENGINE}Air-fuel ratio determination method of gasoline direct injection engine {A METHOD OF DETERMINING AIR FUEL RATIO IN GASOLINE DIRECT INJECTION ENGINE}

본 발명은 가솔린 직접 분사 엔진(gasoline direct injection; GDI)에 관한 것으로서, 더욱 상세하게는 가솔린 직접 분사 엔진의 전자 제어 시스템(electronic management system; EMS)에서 단일의 산소 센서에서 검출되는 신호에 따라 각 운전모드에서의 공연비를 안정되게 제어하도록 하는 가솔린 직접 분사 엔진의 공연비 상태 판정방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasoline direct injection engine (GDI), and more particularly to each operation in accordance with a signal detected by a single oxygen sensor in an electronic management system (EMS) of a gasoline direct injection engine. An air-fuel ratio state determination method of a gasoline direct injection engine for stably controlling an air-fuel ratio in a mode.

현재 개발되어 양산되고 있는 전자 제어 시스템은 보통 MPI(munti point injection)용으로 연료 분사계의 구동 제어가 상대적으로 간단하고, 여러 제어 사양의 제어 수준도 단순하다.Electronic control systems currently in development and in mass production are typically relatively simple to control fuel injection systems for muti point injection (MPI).

최근에는 연료실내에 연료를 직접 분사하는 가솔린 직접 분사 엔진이 여러 자동차 메이커로부터 주목받아 개발되고 있다. 가솔린 직접 분사 엔진은 부분 부하의 경우에는 압축 행정이 끝날 무렵에 연료를 분사하여 점화 플러그 주위의 공연비를 농후하게 하는 성층연소로 초희박 공연비(25:1 ~ 40:1)에서도 쉽게 점화가 가능하도록 되어 있으며, 고부하의 경우에는 흡입 행정이 시작할 무렵에 연료를 분사하여 이론 공연비(14.7:1) 연료에 의한 흡입공기 냉각으로 충진 효율을 향상시킬 수 있다. 또한 가솔린 직접 분사 엔진은 실린더 안으로 연료를 직접 분사하므로 흡기포트 벽에 연료가 흡착되는 월 웨팅(wall wetting) 현상도 줄일 수 있다.Recently, a gasoline direct injection engine that directly injects fuel into a fuel chamber has been developed by attracting attention from various automobile manufacturers. The gasoline direct injection engine is a stratified combustion that injects fuel at the end of the compression stroke in the case of partial load to increase the air-fuel ratio around the spark plug, so that it can be easily ignited even in ultra-thin air-fuel ratios (25: 1 to 40: 1). In the case of high load, the fuel is injected at the beginning of the intake stroke to improve the filling efficiency by cooling the intake air by the theoretical air-fuel ratio (14.7: 1) fuel. In addition, the gasoline direct injection engine directly injects fuel into the cylinder, thereby reducing wall wetting of fuel adsorbed on the intake port wall.

그러나 가솔린 직접 분사 엔진은 MPI 엔진에 비해 연료 분사계가 복잡(예를 들어 고압 연료 펌프 제어, 인젝터 드라이버 제어가 추가되고 연료 분사 압력 피드백 제어가 필요하다)하고 추가되는 제어 사양이 복잡하다. 구체적으로 MPI 엔진은 워밍업 후 한가지 모드(이론 공연비 영역)만 가지나, 가솔린 직접 분사 엔진은 이론 공연비, 희박 운전영역, 초희박 운전영역 등 3가지 영역이 존재한다.However, gasoline direct injection engines have more complicated fuel injection systems than MPI engines (for example, high pressure fuel pump control, injector driver control and fuel injection pressure feedback control). Specifically, the MPI engine has only one mode (theoretical air-fuel ratio area) after warming up, but the gasoline direct injection engine has three areas such as theoretical air-fuel ratio, lean driving area, and ultra-lean driving area.

이상적으로는 가솔린 직접 분사 엔진은 초희박 운전영역만이 존재하겠지만, 실제 차량의 속도가 일정 속도 이하이고 수온이 일정 온도 이하일 때는 운전의 안전성을 위해 이론 공연비 운전을 유지해야 하고, 이론 공연비 영역과 초희박 운전 영역의 중간에 희박 운전 영역을 만들어 양 영역을 자주 왕복하는 것에 대한 충격을 최소화해야 한다.Ideally, gasoline direct injection engines will only have ultra-thin driving zones, but when the actual vehicle speed is below a certain speed and the water temperature is below a certain temperature, the theoretical air-fuel ratio should be maintained for driving safety. A lean drive zone should be created in the middle of the lean drive zone to minimize the impact of frequent round trips between the two zones.

따라서 이러한 세가지 모드의 고유값을 결정할 기준을 만들어야 하며, 결정된 모드 값에 따른 연료 분사량, 연료 분사 시기, 점화시기, 공기 개도량 등의 값을 구해야 한다.Therefore, a criterion to determine the eigenvalues of these three modes should be made, and values such as fuel injection amount, fuel injection timing, ignition timing, and air opening amount according to the determined mode values should be obtained.

종래 MPI 의 전자 제어 시스템에서의 산소 센서 판정은 이론 공연비에 대하여만 수행하였다. 그리고 농후 공연비에서는 +1 볼트를 출력하고, 희박 공연비에서는 0 볼트를 출력하여 제어하였다.Oxygen sensor determination in the conventional MPI electronic control system was performed only for theoretical air-fuel ratio. In the rich air-fuel ratio, +1 volt was output, and in the lean air-fuel ratio, 0 volt was output and controlled.

그러나 가솔린 직접 분사 엔진에서는 산소 센서 판정을 이론 공연비, 희박 공연비, 초희박 공연비 각각을 기준으로 희박/농후 판정을 하여야 한다. 그리고 공연비에 따라 센서의 신호 특성도 달라지므로 로직의 변환이 필요하다.However, in gasoline direct injection engines, oxygen sensor determination should be based on lean / rich determination based on the theoretical air fuel ratio, lean air fuel ratio, and ultra lean air fuel ratio. In addition, the signal characteristics of the sensor vary depending on the air-fuel ratio.

본 발명은 이와 같은 문제점을 해결하기 위한 것으로서, 본 발명의 목적은 가솔린 직접 분사 엔진에서 단일의 산소센서를 적용하여 이론 공연비, 희박 공연비, 초희박 공연비의 상태를 판정하고, 각 상태에 따라 적합한 공연비 제어가 수행되도록 하는 것이다.The present invention is to solve such a problem, an object of the present invention is to determine the state of the theoretical air-fuel ratio, lean air-fuel ratio, ultra-thin air-fuel ratio by applying a single oxygen sensor in the gasoline direct injection engine, and suitable air-fuel ratio according to each state Control is performed.

도 1은 본 발명의 실시 예에 따른 가솔린 직접 분사 엔진의 농후/희박 판정 시스템을 개략적으로 나타낸 도면이다.1 is a view schematically showing a rich / lean determination system of a gasoline direct injection engine according to an embodiment of the present invention.

이하 본 발명의 실시 예를 첨부된 도면을 참조하여 설명한다.Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

본 발명의 실시 예에 따른 산소 센서 출력 신호의 처리 과정은 다음과 같다.Processing of the oxygen sensor output signal according to an embodiment of the present invention is as follows.

배기가스에 포함되는 산소 농도의 검출을 통해 현재의 공연비에서 희박/농후를 판정하는 신호를 출력하는 산소 센서를 하나의 산소센서로 적용하며, 산소센서로부터 측정된 전압을 아날로그-디지털 변환기(analog-digital converter)를 통하여 출력 전압을 디지털 신호로 변환시킨다.An oxygen sensor that outputs a signal to determine the lean / rich at the current air-fuel ratio by detecting the oxygen concentration contained in the exhaust gas is applied to one oxygen sensor, and the voltage measured from the oxygen sensor is converted into an analog-to-digital converter. The output voltage is converted into a digital signal through a digital converter.

산소 센서 아날로그 디지털 변환 값이 임계(threshold) 값보다 큰 경우에는 공연비가 농후인 상태인 것으로 판정하고, 임계(threshold) 값보다 작은 경우에는 공연비가 희박한 것으로 판정한다.When the oxygen sensor analog-to-digital conversion value is larger than the threshold value, it is determined that the air-fuel ratio is rich, and when it is smaller than the threshold value, it is determined that the air-fuel ratio is lean.

도 1은 본 발명의 실시 예에 따른 가솔린 직접 분사 엔진의 농후/희박 판정 시스템을 개략적으로 나타낸 도면이다.1 is a view schematically showing a rich / lean determination system of a gasoline direct injection engine according to an embodiment of the present invention.

도 1에 도시된 바와 같이 본 발명의 실시 예에 따른 가솔린 직접 분사 엔진에서 각 운전모드, 즉 이론 공연비, 희박 연소 모드, 초희박 연소모드에 대하여 농후/희박을 판정하는 시스템은 운전모드 교정 맵(calibration map), 이론 공연비 모드 스위치, 희박연소 운전모드 스위치, 초희박 연소 운전모드 스위치, 농후/희박 보정을 위한 람다 값 설정부, 농후/희박 판정부를 포함한다.As shown in FIG. 1, in the gasoline direct injection engine according to an exemplary embodiment of the present invention, a system for determining rich / lean for each operation mode, that is, theoretical air-fuel ratio, lean combustion mode, and ultra-lean combustion mode, has an operation mode correction map ( calibration map), theoretical air-fuel ratio mode switch, lean burn operation mode switch, ultra lean burn operation mode switch, lambda value setting unit for rich / lean correction, rich / lean determination unit.

운전모드 교정 맵은 입력되는 엔진 회전속도와 필요로 하는 엔진 부하의 상대값에 대응되는 주행상태의 운전모드를 기록한 맵으로서, 이 맵에 기록된 값은 엔진의 종류 및 조건 등에 따라 결정되며 실험에 의해 최적의 값이 구해진다.운전모드 교정 맵은 각각 이론 공연비 운전영역(EHMLMDM), 희박 연소 운전영역(ESMLMDM), 초희박 연소 운전영역(LSMLMDM)을 나타내며, 이들 맵 값은 메모리에 저장된다.The driving mode calibration map is a map that records the driving mode of the driving state corresponding to the relative value of the engine rotation speed and the required engine load. The value recorded in this map is determined according to the type and condition of the engine. The optimum values are obtained. The operation mode calibration maps represent the theoretical air-fuel ratio operation region EHMLMDM, the lean combustion operation region ESMLMDM, and the ultra-lean combustion operation region LSMLMDM, respectively, and these map values are stored in the memory.

이론 공연비 운전모드 스위치(EHM), 희박 연소 운전모드 스위치(ESM), 초희박 연소 운전모드 스위치(LSM)는 각각 본 발명의 실시 예에 따라 결정된 운전모드를 운전모드 교정 맵으로부터 입력받아 해당 운전 모드에 대응하는 운전모드를 스위칭하는 역할을 한다.Theoretical air-fuel ratio operation mode switch (EHM), lean combustion operation mode switch (ESM), ultra-thin combustion operation mode switch (LSM) receives the operation mode determined according to the embodiment of the present invention from the operation mode calibration map, respectively, and the corresponding operation mode. It serves to switch the operation mode corresponding to.

상기 농후/희박 판정부는 산소 센서 아날로그 디지털 변환 값이 농후/희박 판정 기준 람다 값의 전압 변환 값에서 희박 판정시 델타 값을 뺀 것보다 작은 경우에는 공연비가 농후한 것으로 판단하여 농후/희박 판정 플래그를 1로 설정한다. 상기 희박 판정시 델타 값은 19.5mV이다.The rich / lean determination unit judges that the air / fuel ratio is rich when the oxygen sensor analog-digital conversion value is smaller than the voltage conversion value of the rich / lean determination standard lambda value by subtracting the delta value. Set to 1. In the lean determination, the delta value is 19.5 mV.

또한 상기 농후/희박 판정부는 산소 센서 아날로그 디지털 변환 값이 농후/희박 판정 기준 람다(lambda) 값의 전압 변환 값에서 농후 판정시 델타 값을 더한 것보다 큰 경우에는 공연비가 희박한 것으로 판단하여 농후/희박 판정 플래그를 0으로 설정한다. 상기 농후 판정시 델타 값은 19.5mV이다.In addition, the rich / lean determination unit determines that the air-fuel ratio is thin when the oxygen sensor analog-digital conversion value is greater than the voltage conversion value of the rich / lean determination standard lambda value plus the delta value in the rich determination. Set the decision flag to zero. In the rich determination, the delta value is 19.5 mV.

이론 공연비 운전모드인 경우에는 람다를 1로 하고 이때 상기 농후/희박 판정 기준 람다 값의 전압 변환 값은 2.50V가 된다.In the theoretical air-fuel ratio operation mode, the lambda is 1, and the voltage conversion value of the rich / lean determination criterion lambda value is 2.50V.

희박 운전모드인 경우에는 람다를 1.428로 하고 이때 상기 농후/희박 판정 기준 람다 값의 전압 변환 값은 3.69V가 된다.In the lean operation mode, the lambda is 1.428, and the voltage conversion value of the rich / lean determination reference lambda is 3.69V.

초희박 운전모드인 경우에는 람다를 2.425로 하고 이때 상기 농후/희박 판정 기준 람다 값의 전압 변환 값은 4.91V가 된다.In the ultra-lean operation mode, the lambda is 2.425, and the voltage conversion value of the rich / lean determination reference lambda value is 4.91V.

이상에서는 본 발명의 실시 예를 설명하였으나, 본 발명은 상기한 실시 예에만 한정되는 것은 아니며 그 외의 다양한 변형이나 변경이 가능하다.Although the embodiments of the present invention have been described above, the present invention is not limited only to the above embodiments, and various other modifications and changes are possible.

이상에서 설명한 바와 같이, 본 발명에 따르면 가솔린 직접 분사 엔진에 적용되는 3가지 운전 모드에서 산소 센서에서 출력되는 신호로 공연비 상태를 판단할 수 있다.As described above, according to the present invention, the air-fuel ratio state may be determined by signals output from the oxygen sensor in three operation modes applied to the gasoline direct injection engine.

Claims (2)

가솔린 직접 분사 엔진에 있어서,In a gasoline direct injection engine, 스로틀 밸브의 상대 개도율과 엔진 회전수로부터 현재의 운전 모드가 이론 공연비 운전 모드, 희박 운전 모드, 초희박 운전 모드 중 어느 운전 모드상에 있는지를 판별하는 단계;Determining whether the current operation mode is in a theoretical air-fuel ratio operation mode, a lean operation mode, or an ultra-lean operation mode from the relative opening ratio and engine speed of the throttle valve; 상기 판별되는 운전모드에 설정된 교정된 맵 값을 적용하는 단계와;Applying a calibrated map value set to the determined operation mode; 상기 교정된 맵 값이 적용된 현재의 운전모드에 단일의 산소 센서로부터 검출되는 배기가스에 포함된 산소의 농도값를 적용하여 현재의 운전모드에서 희박/농후 여부를 판정하는 단계 및;Determining whether lean / rich is present in the current operation mode by applying a concentration value of oxygen contained in exhaust gas detected from a single oxygen sensor to the current operation mode to which the corrected map value is applied; 상기 판정되는 결과에 따라 이론 공연비 운전모드, 희박 운전모드, 초희박 운전모드에 대하여 공연비 제어를 수행하는 단계를 포함하는 것을 특징으로 하는 가솔린 직접 분사 엔진의 공연비 상태 판정방법.And an air-fuel ratio control for the theoretical air-fuel ratio operation mode, the lean operation mode, and the ultra-thin operation mode according to the determined result. 삭제delete
KR10-2000-0087019A 2000-12-30 2000-12-30 A method of determining air fuel ratio in gasoline direct injection engine KR100427294B1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08158921A (en) * 1994-12-08 1996-06-18 Unisia Jecs Corp Air-fuel ratio control device of internal combustion engine
KR19990013481A (en) * 1997-07-01 1999-02-25 하나와기이찌 Fuel injection control system for internal combustion engines
JPH11247688A (en) * 1998-02-27 1999-09-14 Toyota Motor Corp Control device of internal combustion engine
JP2000054887A (en) * 1998-08-05 2000-02-22 Mitsubishi Motors Corp Internal combustion engine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08158921A (en) * 1994-12-08 1996-06-18 Unisia Jecs Corp Air-fuel ratio control device of internal combustion engine
KR19990013481A (en) * 1997-07-01 1999-02-25 하나와기이찌 Fuel injection control system for internal combustion engines
KR100317159B1 (en) * 1997-07-01 2002-02-19 하나와 요시카즈 Fuel injection control system for internal combustion engine
JPH11247688A (en) * 1998-02-27 1999-09-14 Toyota Motor Corp Control device of internal combustion engine
JP2000054887A (en) * 1998-08-05 2000-02-22 Mitsubishi Motors Corp Internal combustion engine

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