Abstract: During idle operation of an engine, on satisfaction of a predetermined condition including a condition that a vehicle speed is not higher than a reference value, a hybrid vehicle controls the engine with adjusting a throttle position such that a rotation speed of the engine becomes equal to target idle rotation speed or is in a predetermined rotation speed range including the target idle rotation speed. On non-satisfaction of predetermined condition, the hybrid vehicle controls the engine with setting the throttle position to a fixed value, The reference value is set to provide larger value when the rotation speed of the engine becomes equal to or lower than a predetermined rotation speed that is lower than the target idle rotation speed and is higher than a resonance rotation speed of the vehicle, compared with a value when the rotation speed of the engine is higher than the predetermined rotation speed.

Abstract: During idle operation of an engine, on satisfaction of a predetermined condition including a condition that a vehicle speed is not higher than a reference value, a hybrid vehicle controls the engine with adjusting a throttle position such that a rotation speed of the engine becomes equal to target idle rotation speed or is in a predetermined rotation speed range including the target idle rotation speed. On non-satisfaction of predetermined condition, the hybrid vehicle controls the engine with setting the throttle position to a fixed value, The reference value is set to provide larger value when the rotation speed of the engine becomes equal to or lower than a predetermined rotation speed that is lower than the target idle rotation speed and is higher than a resonance rotation speed of the vehicle, compared with a value when the rotation speed of the engine is higher than the predetermined rotation speed.

Abstract: When a conversion catalyst in a catalytic converter is warmed up, a required efficiency ?tag is set such as to be within a range of less than 1 that is a value when the conversion catalyst is not warmed up and to increase with an increase in delay of an open-close timing VT of an intake valve (steps S130 to S160). A delayed amount of a target ignition timing IT* is decreased with an increase in required efficiency ?tag (closer to the value 1) (steps S170 and S180).

Abstract: Disclosed is a control device applied to an internal combustion engine provided with a fuel vapor treatment system for treating collected fuel vapor by purging the collected fuel vapor into intake air downstream from an air flowmeter (6) and an exhaust gas recirculation system for recirculating part of exhaust gas in the intake air using intake negative pressure. An electronic control unit (22) performs an advance correction corresponding to the exhaust gas recirculation quantity regarding the MBT ignition timing and the knock limit ignition timing, and corrects the volumetric efficiency of the internal combustion engine, which is used for the calculation of the advance correction quantity used for the advance correction, according to the purge air quantity.

Abstract: When an engine is in a predetermined steady operating state, a gradient accumulation average value ?Aulsa corresponding to the amount of change in the air-fuel ratio AF, detected by an air-fuel ratio sensor, over the period of time from when an upper peak is reached, at which the direction of change in the air-fuel ratio AF is inverted to when a lower peak is reached, at which the subsequent inversion of the direction occurs, is calculated (S100 to S160) and, when the calculated gradient accumulation average value ?Aulsa is greater than a predetermined threshold value ?Aref1 that is determined in advance as an upper limit (absolute value) of the range, in which it may be determined that the air-fuel ratio is even between the cylinders of the engine (S165 to S175), it is determined that the engine is in an air-fuel ratio imbalance state, in which there is an imbalance in air-fuel ratio between the cylinders of the engine.

Abstract: The invention relates to an air-fuel ratio control device of an internal combustion engine, comprising a plurality of means for independently introducing into each combustion chamber an exhaust gas discharged from combustion chambers to an exhaust passage. When at least one exhaust gas introduction means is under an exhaust gas introduction shortage state, a target value of an air-fuel ratio of a mixture gas is changed depending on whether an exhaust gas introduction control for introducing the exhaust gas into the combustion chamber by the exhaust gas introduction means is performed.

Abstract: A cooling device circulates cooling water through an engine main body and a radiator using an electric pump and supplies cool air to the radiator using an electric fan, thereby cooling the engine main body. During a dead soak period after an engine is shut off, a control unit controls the operation states of the electric pump and the electric fan on the basis of cooling water temperature detected by a water temperature sensor, outside air temperature detected by an outside air temperature sensor, and battery voltage. Specifically, when the engine is shut off, if it is determined on the basis of the cooling water temperature and the outside air temperature that the engine is in a high temperature state, the control unit controls the electric pump and the electric fan.

Abstract: An air-fuel ratio diagnostic device for an internal combustion engine. The device includes an air-fuel ratio that detects oxygen concentration in the exhaust. A determination unit determines a variation in air-fuel ratio between engine cylinders based on a detection value of the air-fuel ratio sensor. A change amount in the detection value for a certain time when the detection value is changing from a lean side peak value toward a rich side peak value is defined as a rich change rate. A change amount in the detection for a certain time when the detection value is changing from a rich side peak value toward a lean side peak value is defined as a lean change rate. The determination unit determines a degree of variation between the cylinders based on the rich and lean change rates.

Abstract: Disclosed is a control device applied to an internal combustion engine provided with a fuel vapor treatment system for treating collected fuel vapor by purging the collected fuel vapor into intake air downstream from an air flowmeter (6) and an exhaust gas recirculation system for recirculating part of exhaust gas in the intake air using intake negative pressure. An electronic control unit (22) performs an advance correction corresponding to the exhaust gas recirculation quantity regarding the MBT ignition timing and the knock limit ignition timing, and corrects the volumetric efficiency of the internal combustion engine, which is used for the calculation of the advance correction quantity used for the advance correction, according to the purge air quantity.

Abstract: An abnormality determination system for an internal combustion engine includes a plurality of EGR gas supply sections, an EGR gas supply control unit, an air-fuel ratio sensor placed downstream of an exhaust collecting portion, and an abnormality determining unit that determines an abnormality in the internal combustion engine. The abnormality determining unit obtains a change rate corresponding value during shutoff of the EGR gas or during supply of the EGR gas, as an EGR-OFF corresponding value or an EGR-ON corresponding value. The abnormality determining unit obtains a normalized EGR-OFF corresponding value, and obtains a normalized EGR-ON corresponding value. The abnormality determining unit makes an abnormality determines whether one of the EGR gas supply sections is in an abnormal condition in which the EGR gas supply section is blocked, based on a relationship between the normalized EGR-OFF corresponding value and the normalized EGR-ON corresponding value.

Abstract: The invention relates to an air-fuel ratio control device of an internal combustion engine, comprising a plurality of means for independently introducing into each combustion chamber an exhaust gas discharged from combustion chambers to an exhaust passage. When at least one exhaust gas introduction means is under an exhaust gas introduction shortage state, a target value of an air-fuel ratio of a mixture gas is changed depending on whether an exhaust gas introduction control for introducing the exhaust gas into the combustion chamber by the exhaust gas introduction means is performed.

Abstract: An internal combustion engine system includes: an internal combustion engine; a valve regulating exhaust gas flow rate to an intake system; an exhaust gas recirculation system opening the valve to recirculate the exhaust gas to the intake system; an intake air flow rate detecting device detecting air flow rate introduced into the engine; and a controller, when fuel injection is stopped, controlling the engine to start the fuel injection at a rate obtained by adding a first flow rate to a reference flow rate for a stoichiometric air-fuel ratio based on the detected air flow rate when the valve opening degree is lower than a predetermined degree, and controlling the engine to start the fuel injection at a rate obtained by adding a second flow rate, larger than the first flow rate, to the reference flow rate when the valve opening degree is no less than the predetermined degree.

Abstract: An air-fuel ratio diagnostic device for an internal combustion engine. The device includes an air-fuel ratio that detects oxygen concentration in the exhaust. A determination unit determines a variation in air-fuel ratio between engine cylinders based on a detection value of the air-fuel ratio sensor. A change amount in the detection value for a certain time when the detection value is changing from a lean side peak value toward a rich side peak value is defined as a rich change rate. A change amount in the detection for a certain time when the detection value is changing from a rich side peak value toward a lean side peak value is defined as a lean change rate. The determination unit determines a degree of variation between the cylinders based on the rich and lean change rates.

Abstract: When an engine is in a predetermined steady operating state, a gradient accumulation average value ?Aulsa corresponding to the amount of change in the air-fuel ratio AF, detected by an air-fuel ratio sensor, over the period of time from when an upper peak is reached, at which the direction of change in the air-fuel ratio AF is inverted to when a lower peak is reached, at which the subsequent inversion of the direction occurs, is calculated (S100 to S160) and, when the calculated gradient accumulation average value ?Aulsa is greater than a predetermined threshold value ?Aref1 that is determined in advance as an upper limit (absolute value) of the range, in which it may be determined that the air-fuel ratio is even between the cylinders of the engine (S165 to S175), it is determined that the engine is in an air-fuel ratio imbalance state, in which there is an imbalance in air-fuel ratio between the cylinders of the engine.

Abstract: An internal combustion engine system includes: an internal combustion engine; a valve regulating exhaust gas flow rate to an intake system; an exhaust gas recirculation system opening the valve to recirculate the exhaust gas to the intake system; an intake air flow rate detecting device detecting air flow rate introduced into the engine; and a controller, when fuel injection is stopped, controlling the engine to start the fuel injection at a rate obtained by adding a first flow rate to a reference flow rate for a stoichiometric air-fuel ratio based on the detected air flow rate when the valve opening degree is lower than a predetermined degree, and controlling the engine to start the fuel injection at a rate obtained by adding a second flow rate, larger than the first flow rate, to the reference flow rate when the valve opening degree is no less than the predetermined degree.

Abstract: An internal combustion engine includes a port injector injecting a fuel into an intake port, an in-cylinder injector directly injecting a fuel into a combustion chamber, and an ECU. When the ECU determines that an operation state of the internal combustion engine exhibits a transition state, the ECU obtains an estimated load factor of the internal combustion engine based on the operation state of the internal combustion engine, and calculates a fuel injection ratio between the port injector and the in-cylinder injector based on the estimated load factor.

Abstract: An internal combustion engine includes a port injector injecting a fuel into an intake port, an in-cylinder injector directly injecting a fuel into a combustion chamber, and an ECU. When the ECU determines that an operation state of the internal combustion engine exhibits a transition state, the ECU obtains an estimated load factor of the internal combustion engine based on the operation state of the internal combustion engine, and calculates a fuel injection ratio between the port injector and the in-cylinder injector based on the estimated load factor.

Abstract: An apparatus for controlling the idling speed of an engine is disclosed. An idling speed control valve disposed in an idle passage communicates with the intake passage downstream and upstream of the throttle valve to control the amount of the airflow supplied to the idling engine. A neutral start switch outputs an instruction signal to an ECU based on a switching operation of a shift lever from its neutral range to a drive range. Based on the instruction signal, the ECU computes a duty factor to increase the airflow amount through the idle speed control valve to a predetermined amount. The increased airflow amount is subsequently attenuated to a predetermined magnitude with an attenuation factor based on a change rate of the engine speed.