WO2013175592A1 - 内燃機関の空燃比制御装置 - Google Patents
内燃機関の空燃比制御装置 Download PDFInfo
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- WO2013175592A1 WO2013175592A1 PCT/JP2012/063203 JP2012063203W WO2013175592A1 WO 2013175592 A1 WO2013175592 A1 WO 2013175592A1 JP 2012063203 W JP2012063203 W JP 2012063203W WO 2013175592 A1 WO2013175592 A1 WO 2013175592A1
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- fuel ratio
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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
- F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
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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
- F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
- F02D41/1441—Plural sensors
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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
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0007—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using electrical feedback
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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
- F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
- F02D35/0015—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for using exhaust gas sensors
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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
- F02D41/04—Introducing corrections for particular operating conditions
- F02D41/06—Introducing corrections for particular operating conditions for engine starting or warming up
- F02D41/062—Introducing corrections for particular operating conditions for engine starting or warming up for starting
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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
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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
- F02D41/1493—Details
- F02D41/1495—Detection of abnormalities in the air/fuel ratio feedback system
Definitions
- the present invention relates to an air-fuel ratio control apparatus for an internal combustion engine, and more particularly to an air-fuel ratio control apparatus for an internal combustion engine in which air-fuel ratio sensors are provided upstream and downstream of a catalyst provided in an exhaust passage.
- an internal combustion engine in which a sensor having an air-fuel ratio detection function is provided upstream or downstream of a catalyst provided in an exhaust passage is known.
- Various devices are known that perform failure detection of the catalyst using the output of the sensor.
- Patent Document 1 discloses a failure detection device for an air-fuel ratio control device in which two air-fuel ratio sensors are provided upstream and downstream of the catalyst.
- This failure detection device is premised on performing air-fuel ratio feedback control using the output of the air-fuel ratio sensor upstream of the catalyst, and based on the sensor output difference between the upstream and downstream of the catalyst, the two air-fuel ratio sensors Alternatively, the failure (or deterioration) of the catalyst is detected.
- Patent Document 2 discloses an air-fuel ratio control apparatus in which an air-fuel ratio sensor is provided upstream of the catalyst and an oxygen sensor is provided downstream of the catalyst.
- This air-fuel ratio control apparatus is premised on performing air-fuel ratio feedback control using the output of the air-fuel ratio sensor on the upstream side of the catalyst, as in Patent Document 1.
- the output of the oxygen sensor is substituted for the output of the air-fuel ratio sensor until the air-fuel ratio sensor is activated.
- the air-fuel ratio sensor and the oxygen sensor have different sensor structures, and therefore the activation temperature of the air-fuel ratio sensor is higher than that of the oxygen sensor, and it takes a long time for activation. That is, this air-fuel ratio control apparatus performs air-fuel ratio feedback control by temporarily utilizing an oxygen sensor that is activated at a relatively low temperature in view of the difference in the active characteristics of the two types of sensors.
- Patent Document 3 discloses a catalyst deterioration detection device that includes two types of sensors as in Patent Document 2 and detects the deterioration of the catalyst as in Patent Document 1.
- the deterioration detection immediately after the engine is started is performed when a permission condition is satisfied after a predetermined operation that makes the air-fuel ratio upstream of the catalyst lean.
- rich components also referred to as unburned gas components; the same applies hereinafter
- this catalyst deterioration detection device detects the deterioration of the catalyst after removing the rich component adhering to the sensor with lean gas in view of the exhaust characteristic immediately after the engine is started.
- Patent Document 4 discloses an air-fuel ratio control apparatus in which an oxygen sensor is provided downstream of a catalyst and air-fuel ratio feedback control is performed using the output of the oxygen sensor.
- Japanese Unexamined Patent Publication No. 6-280662 Japanese Patent Laid-Open No. 8-261042 Japanese Unexamined Patent Publication No. 2008-121465 Japanese Unexamined Patent Publication No. 4-342848
- the sensor adhering period of rich components in exhaust gas described in Patent Document 3 is not limited to immediately after the engine is started.
- exhaust rich in a rich component stays in the exhaust passage upstream of the catalyst. Therefore, after the engine is stopped, the rich component may adhere to the air-fuel ratio sensor on the upstream side of the catalyst.
- the sensor adhering period of rich components in exhaust gas described in Patent Document 3 is not limited to immediately after the engine is started.
- exhaust rich in a rich component stays in the exhaust passage upstream of the catalyst. Therefore, after the engine is stopped, the rich component may adhere to the air-fuel ratio sensor on the upstream side of the catalyst.
- a porous layer is used for the sensor element, it is inevitable that rich components adhere to the pores.
- the rich component adhering to the air-fuel ratio sensor can be desorbed by increasing the exhaust temperature after restarting the engine. If the rich component can be desorbed, the sensor accuracy of the air-fuel ratio sensor is restored. However, during the desorption of rich components, the atmosphere around the sensor becomes a rich atmosphere. Therefore, during this period, the air-fuel ratio sensor shows an output that is richer than the actual air-fuel ratio. Therefore, when air-fuel ratio feedback control is performed using the output of the upstream air-fuel ratio sensor, the controllability may be deteriorated during the desorption of the rich component.
- an object of the present invention is to provide an air-fuel ratio control device for an internal combustion engine that can suppress deterioration in controllability of air-fuel ratio feedback control after engine restart.
- a first invention is an air-fuel ratio control apparatus for an internal combustion engine, An exhaust purification catalyst provided in the exhaust passage of the internal combustion engine; An upstream air-fuel ratio sensor that is provided in an exhaust passage upstream of the exhaust purification catalyst and continuously outputs a signal corresponding to the air-fuel ratio; A downstream air-fuel ratio sensor provided in an exhaust passage downstream of the exhaust purification catalyst and continuously outputting a signal corresponding to the air-fuel ratio; Use permission for determining whether or not a predetermined use permission condition is satisfied for the output of the upstream air-fuel ratio sensor after the upstream air-fuel ratio sensor and the downstream air-fuel ratio sensor are both activated at the time of starting the internal combustion engine Condition judging means; Starting air-fuel ratio feedback control execution means for executing air-fuel ratio feedback control using the output of the downstream air-fuel ratio sensor until the predetermined use permission condition is satisfied; It is characterized by providing.
- the second invention is the first invention, wherein After the predetermined use permission condition is established, main air-fuel ratio feedback control using the output of the upstream air-fuel ratio sensor and sub air-fuel ratio feedback control using the output of the downstream air-fuel ratio sensor are executed. It is characterized by.
- the third invention is the first or second invention, wherein
- the predetermined use permission condition is whether or not an output difference between the output of the upstream air-fuel ratio sensor and the output of the downstream air-fuel ratio sensor is smaller than a predetermined deviation over a set period. .
- 4th invention is 1st or 2nd invention
- the predetermined use permission condition is whether or not a set period has elapsed.
- the starting air-fuel ratio feedback control execution means prohibits execution of air-fuel ratio feedback control using the output of the upstream air-fuel ratio sensor until the predetermined use permission condition is satisfied.
- the air-fuel ratio feedback is performed using the output of the downstream air-fuel ratio sensor until a predetermined use permission condition is satisfied. Control can be executed.
- exhaust gas containing rich components stays in the exhaust passage after the engine is stopped. Therefore, the upstream air-fuel ratio sensor is affected by the adhesion of rich components.
- the concentration of the rich component is low on the downstream side of the exhaust purification catalyst, and therefore, the downstream air-fuel ratio sensor has a small influence on the attachment of the rich component.
- the main air-fuel ratio feedback control using the output of the upstream air-fuel ratio sensor and the sub air-fuel ratio using the output of the downstream air-fuel ratio sensor Since the feedback control can be executed, it is possible to improve the emission performance after the restart.
- the predetermined use permission condition can be determined based on whether or not the output difference is smaller than a predetermined deviation over a set period.
- the upstream air-fuel ratio sensor and the downstream air-fuel ratio sensor are sensors having similar output characteristics. Therefore, monitoring of the output difference is easy. Therefore, according to the third aspect of the present invention, the completion of desorption of the rich component from the upstream air-fuel ratio sensor can be determined by a simple method.
- the predetermined use permission condition can be determined based on whether or not the set period has elapsed. Therefore, according to the fourth aspect, as with the third aspect, it is possible to determine the completion of desorption of the rich component from the upstream air-fuel ratio sensor by a simple method.
- the execution of the air-fuel ratio feedback control using the output of the upstream air-fuel ratio sensor is prohibited until the predetermined use permission condition is satisfied. Deterioration of controllability can be reliably suppressed.
- FIG. 3 is a flowchart showing an air-fuel ratio feedback control routine executed by an ECU 20 in the first embodiment.
- the elapsed time after engine starting and the output value of the front A / F sensor 16 and the rear A / F sensor 18 are shown.
- 6 is a flowchart showing an air-fuel ratio feedback control routine executed by the ECU 20 in the second embodiment.
- FIG. 1 is a diagram showing a system configuration of the air-fuel ratio control apparatus according to the first embodiment.
- the system of this embodiment includes an engine 10 as a vehicle power device.
- a catalyst 14 is disposed in the exhaust passage 12 of the engine 10.
- the catalyst 14 is a three-way catalyst that efficiently purifies the three components of HC, CO, and NOx in the exhaust when the air-fuel ratio flowing into the catalyst 14 is in a narrow range near the stoichiometric range.
- a front A / F sensor 16 is disposed on the upstream side of the catalyst 14.
- a rear A / F sensor 18 is disposed on the downstream side of the catalyst 14.
- the front A / F sensor 16 and the rear A / F sensor 18 are composed of linear detection sensors that can continuously detect an air-fuel ratio over a relatively wide range, and have passed through the air-fuel ratio flowing into the catalyst 14 and the catalyst 14. A signal proportional to the air-fuel ratio is output.
- the system of this embodiment includes an ECU (Electronic Control Unit) 20.
- ECU Electronic Control Unit
- Connected to the input side of the ECU 20 are the above-described front A / F sensor 16, rear A / F sensor 18, and various other sensors necessary for controlling the vehicle and the engine 10.
- various actuators such as an injector (not shown) for injecting fuel into the engine 10 are connected to the output side of the ECU 20.
- the ECU 20 uses the outputs of the front A / F sensor 16 and the rear A / F sensor 18 to execute various controls such as air-fuel ratio feedback control described below.
- Air-fuel ratio feedback control One of the engine controls by the ECU 20 is air-fuel ratio feedback control.
- a / F feedback control based on the output value of the front A / F sensor 16 (main A / F feedback control) and A / F feedback control based on the output value of the rear A / F sensor 18 (sub (A / F feedback control).
- the main A / F feedback control based on the deviation between the output value of the front A / F sensor 16 and the theoretical air-fuel ratio, the main F / B is reflected in the calculation of the fuel injection amount (calculated from the intake air amount and the engine speed). A value is calculated.
- FIG. 2 is a graph showing the relationship between the elapsed time after engine start and the air-fuel ratio. 2 is measured on the upstream side of the catalyst (that is, in the vicinity of the front A / F sensor 16). As shown in FIG.
- FIG. 3 is an enlarged schematic view of the sensor element portion of the A / F sensor.
- the structure of the sensor element portion 22 shown in this drawing is common to the front A / F sensor 16 and the rear A / F sensor 18.
- the sensor element unit 22 includes a solid electrolyte 24, a pair of electrodes 26, a diffusion-controlling layer 28, a shielding layer 30, and a heater 32.
- the solid electrolyte 24 is made of, for example, a mixture of zirconia and yttria and has a substantially plate shape.
- the electrode 26 is made of, for example, Pt and has a substantially plate shape like the solid electrolyte 24.
- the diffusion control layer 28 is a porous layer made of, for example, alumina particles, and circulates gas.
- the shielding layer 30 is a dense layer made of alumina, for example, and shields gas.
- FIG. 4 is an enlarged view of a portion A in FIG.
- the diffusion control layer 28 is made of alumina particles.
- the rich component is liquefied and adsorbed on the alumina particles.
- FIG. 3 shows the adsorption state of the rich component on the alumina particles.
- the adsorbed rich component is desorbed as the temperature of the sensor element unit 22 increases. That is, the rich component is desorbed by the increase in the exhaust temperature after the engine 10 is restarted.
- the sensor element unit 22 has a rich atmosphere due to the desorbed component. Therefore, during the period (that is, from time T 1 to time T 2 in FIG. 2), the output value of the A / F sensor indicates an output that is richer than the actual A / F.
- the concentration of the unburned gas component is high on the upstream side of the catalyst 14 and decreases as it goes downstream. This is because the unburned gas component is adsorbed by the catalyst 14. That is, it can be said that there is almost no unburned gas component downstream of the catalyst 14 and that the above-described divergence is unlikely to occur in the rear A / F sensor 18. Therefore, in the present embodiment, the air-fuel ratio feedback control is performed without using the output value of the front A / F sensor 16 until a predetermined period elapses after the front A / F sensor 16 and the rear A / F sensor 18 are activated. It was decided to execute.
- calculation of the main F / B value by the front A / F sensor 16 is stopped until the predetermined period elapses, and calculation of the sub F / B value by the rear A / F sensor 18 is performed. Only do. That is, during this period, only the sub F / B value calculated based on the output of the rear A / F sensor 18 is reflected in the fuel injection amount. However, the air-fuel ratio feedback using only the sub F / B value has a small correction amount and is difficult to correct. Therefore, in the sub A / F feedback control during this period, the feedback gain (PID control coefficient) is set to be larger than normal (for example, twice).
- FIG. 5 is a flowchart showing an air-fuel ratio feedback control routine executed by the ECU 20 in the first embodiment. Note that the routine shown in FIG. 5 is repeatedly executed periodically.
- the ECU 20 determines whether or not the precondition is satisfied (step 110). This precondition is satisfied when (i) the engine 10 is requested to start, and (ii) the front A / F sensor 16 and the rear A / F sensor 18 are activated (the sensor warm-up is completed). And If it is determined that this precondition is satisfied, the ECU 20 calculates the sub F / B value using the output value of the rear A / F sensor 18 and controls the fuel injection amount (step 120). ). That is, only the sub feedback control using the output value of the rear A / F sensor 18 is executed. When it is determined that the precondition is not satisfied, the ECU 20 returns to step 110 and determines again whether the precondition is satisfied.
- step 130 the ECU 20 determines whether or not a set time has elapsed.
- the set time corresponds to the above-described fixed period, and an appropriate value stored separately in the ECU 20 is used. The processing in this step is continued until the set time elapses after the above precondition is satisfied.
- the ECU 20 executes normal air-fuel ratio feedback control (step 140). That is, the main F / B value is calculated using the output value of the front A / F sensor 16 and the sub F / B value is calculated using the output value of the rear A / F sensor 18 to calculate the fuel injection amount. To control. That is, the main feedback control using the output value of the front A / F sensor 16 and the sub feedback control using the output value of the rear A / F sensor 18 are executed.
- the calculation of the main F / B value by the front A / F sensor 16 is stopped until the predetermined period elapses, but the calculation of the main F / B value itself does not stop. May be. That is, the main F / B value may be estimated by substituting the output value of the rear A / F sensor 18 with the output value of the front A / F sensor 16. If the output of the front A / F sensor 16 is not used until the predetermined period has elapsed, at least the same effect as in the first embodiment can be obtained.
- the first embodiment is performed.
- Various modifications are possible.
- the catalyst 14 is the “catalyst” in the first invention
- the front A / F sensor 16 is the “upstream air-fuel ratio sensor” in the first invention
- the rear A / F The sensors 18 respectively correspond to the “downstream air-fuel ratio sensors” in the first invention.
- the ECU 20 executes the process of step 130 in FIG. 5
- the “use permission condition determining means” in the first invention executes the process of step 120 in FIG.
- the starting air-fuel ratio feedback control execution means is realized.
- Embodiment 2 a second embodiment of the present invention will be described with reference to FIGS.
- the present embodiment is characterized in that the air-fuel ratio feedback control routine shown in FIG. 7 is executed in the apparatus configuration of FIG. Therefore, the description of the device configuration is omitted.
- FIG. 6 shows the elapsed time after starting the engine and the output values of the front A / F sensor 16 and the rear A / F sensor 18.
- the time T 3 after the output value of the front A / F sensor 16 and the rear A / F sensor 18 is equal. Therefore, if switching to normal air-fuel ratio feedback control is performed at time T 3 , highly accurate air-fuel ratio feedback control that is realistic can be achieved. However, it is necessary to consider the difference between the sensors. Therefore, in the present embodiment, when the difference between the output values of both sensors (output difference Vi) becomes smaller than the conforming value a over a predetermined period (conforming value), it is determined that the output values of both sensors are equal. To do.
- FIG. 7 is a flowchart showing an air-fuel ratio feedback control routine executed by the ECU 20 in the second embodiment. Note that the routine shown in FIG. 7 is repeatedly executed periodically.
- the ECU 20 determines whether or not the precondition is satisfied (step 150), and calculates the main F / B value using the output value of the rear A / F sensor 18 (step 160).
- the processing in steps 150 and 160 is the same as the processing in steps 110 and 120 in FIG.
- step 160 the ECU 20 determines whether or not the output values of the front A / F sensor 16 and the rear A / F sensor 18 are equal (step 170). As described above, the ECU 20 determines that the output values of both sensors are equal when the output difference Vi becomes smaller than the conforming value a over a certain period. The process in this step is continued until it is determined that the output values of both sensors are equivalent. If it is determined that the output difference Vi is equal, the ECU 20 executes normal air-fuel ratio feedback control (step 180). The processing in this step is the same as the processing in step 140 in FIG.
- the sub feedback control using the output value of the rear A / F sensor 18 until the output values of the front A / F sensor 16 and the rear A / F sensor 18 are determined to be equivalent Only executed. Therefore, it is possible to obtain an effect equivalent to the effect of the routine shown in FIG. 5 and to realize an air-fuel ratio feedback control with high accuracy in accordance with reality.
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Abstract
Description
内燃機関の排気通路に設けられた排気浄化触媒と、
前記排気浄化触媒よりも上流側の排気通路に設けられ、空燃比に応じた信号を連続的に出力する上流側空燃比センサと、
前記排気浄化触媒よりも下流側の排気通路に設けられ、空燃比に応じた信号を連続的に出力する下流側空燃比センサと、
前記内燃機関の始動の際、前記上流側空燃比センサと前記下流側空燃比センサとが共に活性化した後に、前記上流側空燃比センサの出力について所定の使用許可条件の成否を判定する使用許可条件判定手段と、
前記所定の使用許可条件が成立するまで、前記下流側空燃比センサの出力を用いて空燃比フィードバック制御を実行する始動時空燃比フィードバック制御実行手段と、
を備えることを特徴とする。
前記所定の使用許可条件の成立後は、前記上流側空燃比センサの出力を用いたメイン空燃比フィードバック制御と、前記下流側空燃比センサの出力を用いたサブ空燃比フィードバック制御とを実行することを特徴とする。
前記所定の使用許可条件は、前記上流側空燃比センサの出力と前記下流側空燃比センサの出力との出力差が設定期間に亘って所定偏差よりも小さいか否かであることを特徴とする。
前記所定の使用許可条件は、設定期間が経過したか否かであることを特徴とする。
前記始動時空燃比フィードバック制御実行手段は、前記所定の使用許可条件が成立するまで、前記上流側空燃比センサの出力を用いた空燃比フィードバック制御の実行を禁止することを特徴とする。
[システム構成の説明]
先ず、図1乃至図5を参照しながら、本発明の実施の形態1について説明する。図1は、実施の形態1の空燃比制御装置のシステム構成を示す図である。図1に示すように、本実施形態のシステムは、車両動力装置としてのエンジン10を備えている。エンジン10の排気通路12には、触媒14が配置されている。触媒14は、これに流入する空燃比がストイキ付近の狭い範囲にある場合に排気中のHC、CO、NOxの3成分を効率的に浄化する三元触媒である。
ECU20によるエンジン制御のひとつに、空燃比フィードバック制御がある。空燃比フィードバック制御では、フロントA/Fセンサ16の出力値に基づくA/Fフィードバック制御(メインA/Fフィードバック制御)と、リアA/Fセンサ18の出力値に基づくA/Fフィードバック制御(サブA/Fフィードバック制御)とが行われている。メインA/Fフィードバック制御では、フロントA/Fセンサ16の出力値と理論空燃比との偏差に基づき、燃料噴射量(吸入空気量およびエンジン回転数により算出)の計算に反映させるメインF/B値が算出される。サブA/Fフィードバック制御では、リアA/Fセンサ18の出力値と、触媒最適浄化点に対応する基準値との偏差が求められ、そのPID制御によって上記燃料噴射量に反映させるサブF/B値が算出される。
図2に示すように、時刻T1においてセンサが活性した後、時刻T2に到るまで、実際の空燃比(実A/F)と、A/Fセンサの出力値との間に乖離が生じる(所謂リッチ出力ズレを起こす)。これは、A/Fセンサの素子部に排気中のリッチ成分が付着しているためである。
図3に示すように、センサ素子部22は、固体電解質24と、一対の電極26と、拡散律速層28と、遮蔽層30と、ヒータ32とを備えている。固体電解質24は、例えばジルコニアとイットリアとの混合物を材料としてなり、略板状をなすものである。電極26は、例えばPtを材料としてなり、固体電解質24同様、略板状をなす。拡散律速層28は、例えばアルミナ粒子を材料とする多孔質層であり、ガスを流通するものである。他方、遮蔽層30は、例えばアルミナを材料する緻密な層であり、ガス遮蔽するものである。
次に、図5を参照しながら、上述した空燃比フィードバック制御の具体的な処理について説明する。図5は、実施の形態1において、ECU20により実行される空燃比フィードバック制御ルーチンを示すフローチャートである。なお、図5に示すルーチンは、定期的に繰り返して実行されるものとする。
また、ECU20が図5のステップ130の処理を実行することにより上記第1の発明における「使用許可条件判定手段」が、同図のステップ120の処理を実行することにより上記第1の発明における「始動時空燃比フィードバック制御実行手段」が、それぞれ実現されている。
次に、図6乃至図7を参照しながら、本発明の実施の形態2について説明する。本実施形態においては、図1の装置構成において、図7に示す空燃比フィードバック制御ルーチンを実行することをその特徴とする。そのため、装置構成の説明については省略する。
上記実施の形態1の空燃比フィードバック制御においては、上記設定時間に適合値を用いた。しかしながら、リッチ出力ズレはリッチ成分の付着量によっても変化する。そのため、フロントA/Fセンサ16の出力値が正常に戻るまでの時間は、再始動前の運転履歴条件に左右される可能性が高い。ところで、上述したように、リアA/Fセンサ18はリッチ成分の付着影響が小さい。つまり、リアA/Fセンサ18の出力値は再始動後から正常値を示している。本実施形態の空燃比フィードバック制御においては、この点に着目し、フロントA/Fセンサ16の出力値がリアA/Fセンサ18の出力値と同等となった時点でリッチ出力ズレの影響が無くなったと判定することとした。
図7を参照しながら、上述した空燃比フィードバック制御の具体的な処理について説明する。図7は、実施の形態2において、ECU20により実行される空燃比フィードバック制御ルーチンを示すフローチャートである。なお、図7に示すルーチンは、定期的に繰り返して実行されるものとする。
12 排気通路
14 触媒
16 フロントA/Fセンサ
18 リアA/Fセンサ
20 ECU
22 センサ素子部
24 固体電解質
26 電極
28 拡散律速層
30 遮蔽層
32 ヒータ
Claims (5)
- 内燃機関の排気通路に設けられた排気浄化触媒と、
前記排気浄化触媒よりも上流側の排気通路に設けられ、空燃比に応じた信号を連続的に出力する上流側空燃比センサと、
前記排気浄化触媒よりも下流側の排気通路に設けられ、空燃比に応じた信号を連続的に出力する下流側空燃比センサと、
前記内燃機関の始動の際、前記上流側空燃比センサと前記下流側空燃比センサとが共に活性化した後に、前記上流側空燃比センサの出力について所定の使用許可条件の成否を判定する使用許可条件判定手段と、
前記所定の使用許可条件が成立するまで、前記下流側空燃比センサの出力を用いて空燃比フィードバック制御を実行する始動時空燃比フィードバック制御実行手段と、
を備えることを特徴とする内燃機関の空燃比制御装置。 - 前記所定の使用許可条件の成立後は、前記上流側空燃比センサの出力を用いたメイン空燃比フィードバック制御と、前記下流側空燃比センサの出力を用いたサブ空燃比フィードバック制御とを実行することを特徴とする請求項1に記載の内燃機関の空燃比制御装置。
- 前記所定の使用許可条件は、前記上流側空燃比センサの出力と前記下流側空燃比センサの出力との出力差が設定期間に亘って所定偏差よりも小さいか否かであることを特徴とする請求項1または2に記載の内燃機関の空燃比制御装置。
- 前記所定の使用許可条件は、設定期間が経過したか否かであることを特徴とする請求項1または2に記載の内燃機関の空燃比制御装置。
- 前記始動時空燃比フィードバック制御実行手段は、前記所定の使用許可条件が成立するまで、前記上流側空燃比センサの出力を用いた空燃比フィードバック制御の実行を禁止することを特徴とする請求項1乃至4何れか1項に記載の内燃機関の空燃比制御装置。
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PCT/JP2012/063203 WO2013175592A1 (ja) | 2012-05-23 | 2012-05-23 | 内燃機関の空燃比制御装置 |
US14/400,870 US20150128574A1 (en) | 2012-05-23 | 2012-05-23 | Air-fuel ratio control device of internal combustion engine |
JP2014516572A JP5928584B2 (ja) | 2012-05-23 | 2012-05-23 | 内燃機関の空燃比制御装置 |
EP12877266.2A EP2853724A1 (en) | 2012-05-23 | 2012-05-23 | Air-fuel ratio control device of internal combustion engine |
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PCT/JP2012/063203 WO2013175592A1 (ja) | 2012-05-23 | 2012-05-23 | 内燃機関の空燃比制御装置 |
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US (1) | US20150128574A1 (ja) |
EP (1) | EP2853724A1 (ja) |
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JP2017075588A (ja) * | 2015-10-16 | 2017-04-20 | ヤンマー株式会社 | エンジンユニット |
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JP6287980B2 (ja) * | 2015-07-03 | 2018-03-07 | トヨタ自動車株式会社 | 内燃機関の制御装置 |
JP6586942B2 (ja) * | 2016-12-26 | 2019-10-09 | トヨタ自動車株式会社 | 内燃機関の制御装置 |
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DE102010030632A1 (de) * | 2010-06-29 | 2011-12-29 | Robert Bosch Gmbh | Verfahren und Vorrichtung zur Dynamiküberwachung einer Lambdasonde |
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2012
- 2012-05-23 WO PCT/JP2012/063203 patent/WO2013175592A1/ja active Application Filing
- 2012-05-23 EP EP12877266.2A patent/EP2853724A1/en not_active Withdrawn
- 2012-05-23 US US14/400,870 patent/US20150128574A1/en not_active Abandoned
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JPH04342848A (ja) | 1991-05-17 | 1992-11-30 | Toyota Motor Corp | 内燃機関の空燃比制御装置 |
JPH06280662A (ja) | 1993-03-30 | 1994-10-04 | Mazda Motor Corp | 空燃比制御装置の故障検出装置 |
JPH08261042A (ja) | 1995-01-27 | 1996-10-08 | Mazda Motor Corp | エンジンの空燃比制御装置 |
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JPWO2013175592A1 (ja) | 2016-01-12 |
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JP5928584B2 (ja) | 2016-06-01 |
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