Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Hideki Takubo

Osamu Maeda

Keiichi Enoki

Osamu Ishikawa

Akira Demizu

Tadahiro Azuma

Provided is a control apparatus for an internal combustion engine which is capable of estimating a single composition concentration based on an air-fuel ratio correction amount obtained by using an output of an air-fuel ratio sensor in exhaust gas and optimizing a fuel injection amount by using a concentration estimation value. When fueling is performed again during alcohol concentration change after the fueling, an alcohol concentration estimation period or a start determination period for the alcohol concentration change is extended by an integrated fuel injection amount from initial fueling until refueling, whereby alcohol concentration estimation accuracy is improved with respect to the alcohol concentration change due to the initial fueling and the refueling.

Control apparatus for an internal combustion engine

The control apparatus for the internal combustion engine includes: a unit for detecting the change in the alcohol concentration of a fuel supplied to the internal combustion engine including a plurality of cylinders; a unit for detecting an air-fuel ratio variation between the plurality of cylinders; a unit for making the failure diagnosis when the air-fuel ratio variation between the plurality of cylinders exceeds a predetermined threshold value; and a unit for inhibiting the failure diagnosis executed based on the air-fuel ratio variation between the plurality of cylinders when the change in the alcohol concentration is detected.

Control apparatus for internal combustion engine

A start control apparatus for an internal combustion engine, which takes an amount of a fuel vaporized from a heated fuel into consideration to prevent deterioration of startability due to an overrich or overlean condition caused by an excessive or insufficient amount of the vaporized fuel and to realize improvement of cold startability. The start control apparatus includes: a heater () for heating a fuel to be supplied to the internal combustion engine; fuel heating control unit () for energizing the heater when a cooling water temperature is less than an internal combustion engine start possible water temperature value to heat the fuel; and start time fuel setting unit () for setting a start time fuel injection amount of the internal combustion engine according to a fuel temperature after the fuel is heated by the fuel heating control unit (), an alcohol concentration, and the cooling water temperature.

Start control apparatus for an internal combustion engine

A control apparatus for an internal combustion engine is provided which, even when a starting time of an alcohol concentration change varies, can accurately detect a starting time of an alcohol concentration estimation, and set a concentration estimation time matched to the behavior of the concentration change after determination of the start of the concentration change. An air fuel ratio correction amount calculation unit calculates an air fuel ratio correction amount based on an air fuel ratio detected by a sensor. An estimation permission determination unit determines that a starting condition for concentration estimation holds, when the correction amount becomes out of a predetermined range, and sets a permission time for concentration estimation in accordance with an accumulated amount of fuel injected after the starting condition for concentration estimation holds. A concentration estimation unit calculates an estimated concentration value based on the correction amount during permission of the concentration estimation.

An air fuel ratio control apparatus for an internal combustion engine can achieve control behavior with good stability and response that is appropriate for a delay in an oxygen storage operation of a catalyst, and can always keep the state of purification of the catalyst adequately. The apparatus includes an upstream oxygen sensor (), a downstream oxygen sensor (), a first air fuel ratio feedback control section () that adjusts an amount of fuel to be supplied so as to make an air fuel ratio in an upstream exhaust gas and an upstream target air fuel ratio (AFobj) coincide with each other, and a second air fuel ratio feedback control section () that operates the upstream target air fuel ratio (AFobj) in accordance with an air fuel ratio deviation between an air fuel ratio detected by the downstream oxygen sensor () and a downstream target air fuel ratio so as to make the detected air fuel ratio of said downstream oxygen sensor () and the downstream target air fuel ratio coincide with each other. The second air fuel ratio feedback control section () sets an integral gain of integral calculation to be larger in accordance with an increasing flow rate of the exhaust gas, and also sets a proportional gain of proportional calculation so as not to be changed with respect to a change in the flow rate of the exhaust gas.

Air fuel ratio control apparatus for an internal combustion engine

Provided is a control device for an internal combustion engine, which can enable stable and fine control of an average air/fuel ratio of an exhaust gas on the upstream side of a catalyst. The control device for an internal combustion engine includes: a catalytic converter; an upstream Osensor to the upstream of the catalyst; a downstream Osensor to the downstream of the catalyst; a first air/fuel ratio feedback control unit for controlling the air/fuel ratio of the exhaust gas based on an output value of the upstream Osensor and a controlling constant group; a second air/fuel ratio feedback control unit for calculating a target average air/fuel ratio AFAVEobj based on the output value of the upstream Osensor and an output target value VR; and a conversion unit for calculating at least two controlling constants by using the target average air/fuel ratio AFAVEobj as a common index.

Control device for internal combustion engine

An air fuel ratio control apparatus for an internal combustion engine can freely change an oscillation width of an amount of oxygen occlusion so as to adapt to or diagnose catalyst degradation without changing the settings of the period or width of the air fuel ratio oscillation. The apparatus includes a first air fuel ratio feedback control section that adjusts the air fuel ratio of a mixture supplied to an engine in accordance with an output value of an upstream air fuel ratio sensor and a predetermined control constant thereby to make the air fuel ratio periodically oscillate in rich and lean directions, and an average air fuel ratio oscillation section that operates the control constant based on an amount of oxygen occlusion of the catalyst so that an average air fuel ratio obtained by averaging the periodically oscillating air fuel ratio is caused to oscillate in the rich and lean directions.

An air fuel ratio control apparatus for an internal combustion engine can improve accuracy in catalyst degradation diagnosis. The apparatus includes a first air fuel ratio feedback control section that adjusts the air fuel ratio of a mixture supplied to an engine in accordance with an output of an upstream air fuel ratio sensor and a predetermined control constant thereby to make the air fuel ratio periodically oscillate in rich and lean directions, an average air fuel ratio oscillation section that operates the control constant based on an amount of oxygen occlusion of a catalyst so that an average air fuel ratio obtained by averaging the periodically oscillating air fuel ratio is caused to oscillate in the rich and lean directions, and a catalyst degradation diagnosis section that diagnoses catalyst degradation based on correlation between the oscillation of the average air fuel ratio and an output of the downstream oxygen sensor.

In an air-fuel ratio feedback control device for a fuel injection control system, a catalyst deterioration diagnosing means for carrying out deterioration diagnosis of the catalyst is equipped with a diagnosis permission judging means for judging permission of the deterioration diagnosis of the catalyst on the basis of a driving area of the internal combustion engine, an air-fuel ratio varying means for varying the target upstream air-fuel ratio at the catalyst deterioration diagnosis time, a catalyst deterioration judging means for judging the deterioration of the catalyst on the basis of the downstream air-fuel ratio detection output at the catalyst deterioration diagnosis time, and a catalyst deterioration diagnosis prohibiting means for setting a deterioration diagnosis prohibition time of the catalyst after the catalyst deterioration diagnosis.

Air-fuel ratio feedback control device

An air-fuel ratio control apparatus for an internal combustion engine, including fuel cut state detection means for detecting the state of fuel cut in which the feed of fuel into the internal combustion engine is stopped, and catalyst deterioration decision means for deciding the deterioration of a catalyst on the basis of a period which is expended since the detection of the release of the state of the fuel cut by the fuel cut state detection means, until the output value of a second air-fuel ratio sensor agrees with a predetermined reset decision value near a target value, and the manipulation quantity of an average air-fuel ratio on the upstream side of the catalyst as is based on second air-fuel ratio feedback control means. Thus, the deterioration of the catalyst can be decided at a high precision.

Air-fuel ratio control apparatus for internal combustion engine

A control apparatus for an internal combustion engine can learn an alcohol concentration of fuel in a fuel tank according to air fuel ratio feedback control, and accurately calculate, even upon interruption of learning, an alcohol concentration in an injector by estimating an alcohol concentration change delay from the fuel tank to the injector. The alcohol concentration in the fuel tank is estimated based on an air fuel ratio correction amount calculated from an air fuel ratio detected. A delay behavior of an alcohol concentration change until the fuel in the fuel tank reaches the injector is estimated. The alcohol concentration of fuel supplied to the engine is calculated from the estimated alcohol concentration in the fuel tank and the estimated delay behavior. An alcohol concentration correction coefficient is calculated based on the alcohol concentration, and an amount of fuel supplied to the engine is corrected by the correction coefficient.

An air-fuel ratio control device for an internal combustion engine can detect the deteriorated purification state of a catalyst without delay after completion of rich or lean control, and can rapidly restore the purification state. A filter process constant for a downstream Osensor output is set smaller when rich or lean control are performed, thus allowing detection of the deteriorated purification state of the catalyst without delay. After the rich or lean control is completed, a dual Ocontrol system is used to rapidly restore the purification state. Further, the impact of downstream Osensor output variation when the catalyst is deteriorated can be suppressed, and stability of the dual Ocontrol system can be maintained.

Air-fuel ratio control device for internal combustion engine

A control apparatus for an internal combustion engine, which makes it possible to ensure quick recovery of a storage amount of oxygen saturated due to a fuel cut, to restore the capacity of a catalytic converter to absorb air-fuel ratio disturbances, and to suppress torque fluctuations through prevention of overcorrection of the air-fuel ratio during normal operation. The control apparatus for an internal combustion engine according to the present invention is equipped with a proportional gain changeover unit. This unit makes a changeover in a proportional gain for proportional calculation in a downstream-side control unit for a predetermined period from a normal proportional gain to a post-fuel-cut proportional gain set larger than the normal proportional gain by a predetermined value, when a fuel cutoff unit starts cutting the fuel supply.

An integral operation in an upstream target-value varying part is stopped in response to transition to a fuel cutoff state to maintain an integral value concerning a downstream side. Thereafter, at a time of removal of the fuel cutoff state, a cumulative-air-intake-amount detecting part detects a cumulative air amount of air taken into an engine. Then, when the cumulative air amount reaches a predetermined air amount, an integral-operation-stop/restart controlling part restarts the integral operation in the upstream target-value varying part to update integral values concerning the downstream side in a time sequence.

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Tokyo, Japan

Hideki Takubo