Abstract: A decrease in purification performance of a system as a whole is suppressed in cases where catalysts are arranged in an upstream side portion and in a downstream side portion of an exhaust passage in an internal combustion engine. A first catalyst, a sensor and a second catalyst are sequentially arranged in the exhaust passage of the internal combustion engine, wherein a switch is made between lean control and rich control in such a manner that an amount of increase or decrease in a storage amount of oxygen falls within a predetermined range, and in cases where the rich control is carried out after performing a predetermined number of times of rich control, the rich control is continued until an air fuel ratio detected by the sensor becomes equal to or less than a rich determination threshold value which is smaller than a stoichiometric air fuel ratio.

Abstract: A decrease in purification performance of a system as a whole is suppressed in cases where catalysts are arranged in an upstream side portion and in a downstream side portion of an exhaust passage in an internal combustion engine. A first catalyst, a sensor and a second catalyst are sequentially arranged in the exhaust passage of the internal combustion engine, wherein a switch is made between lean control and rich control in such a manner that an amount of increase or decrease in a storage amount of oxygen falls within a predetermined range, and in cases where the rich control is carried out after performing a predetermined number of times of rich control, the rich control is continued until an air fuel ratio detected by the sensor becomes equal to or less than a rich determination threshold value which is smaller than a stoichiometric air fuel ratio.

Abstract: An exhaust purification system of the internal combustion engine comprises: an upstream side catalyst 20 arranged in an exhaust passage, a downstream side catalyst 24 arranged at a downstream side of the upstream side catalyst, an air-fuel ratio sensor 41 detecting an air-fuel ratio of outflowing exhaust gas flowing out from the upstream side catalyst, an air-fuel ratio control part 31 controlling an air-fuel ratio of inflowing exhaust gas flowing into the upstream side catalyst to a target air-fuel ratio, and a temperature calculating part 32 calculating a temperature of the downstream side catalyst. The air-fuel ratio control part switches the first control to the second control when a temperature of the downstream side catalyst calculated by the temperature calculating part rises to a reference temperature which is equal to or higher than an activation temperature of the downstream side catalyst.

Abstract: The control system of the internal combustion engine comprises a control part controlling an air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst. The control part alternately sets a target air-fuel ratio between a rich air-fuel ratio and a lean air-fuel ratio and controls the air-fuel ratio of the exhaust gas so that an output air-fuel ratio of the air-fuel ratio sensor becomes the target air-fuel ratio. The control part corrects the output air-fuel ratio of the air-fuel ratio sensor so that when a scavenging occurs, the air-fuel ratio of the exhaust gas changes to a rich side more than an amount of deviation expected to occur in the output air-fuel ratio due to the occurrence of the scavenging. The control part increases a lean degree of the target air-fuel ratio when the scavenging occurs compared with when the scavenging does not occur.

Abstract: A sensor system includes: a controller configured to: predict a temperature of exhaust gas of an internal combustion engine in a position in which an exhaust gas sensor having a sensor element is arranged; and control a heater so as to make a temperature of the sensor element close to a target temperature included in a predetermined range, wherein in cases where the predicted temperature of the exhaust gas is higher than a reference temperature, the controller is configured to make the target temperature lower when the predicted temperature is high than when it is low, within a range lower than the reference temperature, whereas in cases where the predicted temperature is lower than the reference temperature, the controller is configured to make the target temperature lower when the predicted temperature is high than when it is low, within a range higher than the reference temperature.

Abstract: An exhaust purification system of the internal combustion engine comprises: an upstream side catalyst 20 arranged in an exhaust passage, a downstream side catalyst 24 arranged at a downstream side of the upstream side catalyst, an air-fuel ratio sensor 41 detecting an air-fuel ratio of outflowing exhaust gas flowing out from the upstream side catalyst, an air-fuel ratio control part 31 controlling an air-fuel ratio of inflowing exhaust gas flowing into the upstream side catalyst to a target air-fuel ratio, and a temperature calculating part 32 calculating a temperature of the downstream side catalyst. The air-fuel ratio control part switches the first control to the second control when a temperature of the downstream side catalyst calculated by the temperature calculating part rises to a reference temperature which is equal to or higher than an activation temperature of the downstream side catalyst.

Abstract: A fuel supply system for use with an internal combustion engine has a check valve and a purge valve disposed in a purge passage that extends from a canister to connect with an intake passage of the internal combustion engine. A controller regulates the purge valve open with a first opening degree or a first duty ratio during a purge operation. The controller may also regulate the purge valve to open with a second opening degree larger than the first opening degree or a second duty ratio larger than the first duty ratio a predetermined time after initiating the purge operation.

Abstract: The exhaust purification system comprises a control apparatus performing main feedback control controlling the amount of fed fuel so that the output air-fuel ratio of the upstream side sensor becomes a target value, sub feedback control setting the target air-fuel based on the output air-fuel ratio of the downstream side sensor, main learning control controlling the amount of fed fuel based on a main learning value, and sub learning control controlling the amount of fed fuel based on a sub learning value. The control apparatus performs sub learning promotion control so that the sub learning value easily changes to a suitable value when a sub learning promotion condition, which is satisfied when the absolute values of the main learning value and the sub learning value are respectively predetermined reference absolute values or more and these learning values are opposite in sign, is satisfied.

Abstract: The fuel pressure sensor abnormality diagnosis apparatus diagnoses that a fuel pressure sensor is abnormal in the case where, because a state where a detected value of the fuel pressure sensor is less than a target value occurs, a fuel discharge amount of a fuel pump is increased, and as a result, the fuel discharge amount reaches its maximum amount, and even if a predetermined period has elapsed since the fuel discharge amount reaches its maximum amount, the detected value is less than the target value.

Abstract: An electronic control unit provided in an internal combustion engine detects a degree of inter-cylinder variation of the amount of fuel that is injected from a port injector, and a degree of inter-cylinder variation of the amount of fuel that is injected from an in-cylinder injector. In a case where the inter-cylinder variation of one of the port injector and the in-cylinder injector is equal to or greater than a predefined value, a process is executed of limiting, so as not to exceed an upper limit value, an injection proportion of the injector for which the inter-cylinder variation is equal to or greater than the predefined value. This upper limit value is set to be smaller as the degree of inter-cylinder variation of the injector, for which the inter-cylinder variation is equal to or greater than a predefined value, increases.

Abstract: A fuel supply system adapted to supply fuel to an internal combustion engine has both a check valve and a purge valve disposed in a purge passage that extends from a canister to connect with an intake passage of the internal combustion engine. A controller estimates a pressure within an intermediate purge passage of the purge passage located between the check valve and the purge valve without relying on the use of a separate pressure detection device to provide information regarding the same.

Abstract: A control apparatus for an internal combustion engine includes an electronic control unit. The electronic control unit corrects a target air-fuel ratio in an air-fuel ratio control with a first correction value set based on a degree of variation among cylinders in terms of a fuel amount to be injected from the port injector, and a second correction value set based on a degree of variation among the cylinders in terms of a fuel amount to be injected from the in-cylinder injector. A first correction amount of the target air-fuel ratio by the first correction value is set to be larger as an injection amount ratio of the intake-port fuel injection valve is larger, and a second correction amount of the target air-fuel ratio by the second correction value is set to be larger as an injection amount ratio of the in-cylinder fuel injection valve is larger.

Abstract: An electronic control unit executes air-fuel ratio control composed of main feedback correction and sub-feedback correction. The main feedback correction uses an output value of an upstream side sensor in upstream side of a catalyst. The sub-feedback correction uses an output value of a downstream side sensor in downstream side of the catalyst. When there are cylinder-to-cylinder variations in a fuel injection amount of each fuel injection valve, the electronic control unit corrects the fuel injection amount. Each time the degree of the cylinder-to-cylinder variations is lower than or equal to a first predetermined value, the electronic control unit stores the sub-learning value at that point in time as a normal value, and, when the degree of the cylinder-to-cylinder variations is higher than or equal to a second predetermined value, the electronic control unit changes the sub-learning value to the stored normal value.

Abstract: The exhaust purification system comprises a control apparatus performing main feedback control controlling the amount of fed fuel so that the output air-fuel ratio of the upstream side sensor becomes a target value, sub feedback control setting the target air-fuel based on the output air-fuel ratio of the downstream side sensor, main learning control controlling the amount of fed fuel based on a main learning value, and sub learning control controlling the amount of fed fuel based on a sub learning value. The control apparatus performs sub learning promotion control so that the sub learning value easily changes to a suitable value when a sub learning promotion condition, which is satisfied when the absolute values of the main learning value and the sub learning value are respectively predetermined reference absolute values or more and these learning values are opposite in sign, is satisfied.

Abstract: The control system of the internal combustion engine comprises a control part controlling an air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst. The control part alternately sets a target air-fuel ratio between a rich air-fuel ratio and a lean air-fuel ratio and controls the air-fuel ratio of the exhaust gas so that an output air-fuel ratio of the air-fuel ratio sensor becomes the target air-fuel ratio. The control part corrects the output air-fuel ratio of the air-fuel ratio sensor so that when a scavenging occurs, the air-fuel ratio of the exhaust gas changes to a rich side more than an amount of deviation expected to occur in the output air-fuel ratio due to the occurrence of the scavenging. The control part increases a lean degree of the target air-fuel ratio when the scavenging occurs compared with when the scavenging does not occur.

Abstract: The fuel pressure sensor abnormality diagnosis apparatus diagnoses that a fuel pressure sensor is abnormal in the case where, because a state where a detected value of the fuel pressure sensor is less than a target value occurs, a fuel discharge amount of a fuel pump is increased, and as a result, the fuel discharge amount reaches its maximum amount, and even if a predetermined period has elapsed since the fuel discharge amount reaches its maximum amount, the detected value is less than the target value.

Abstract: An electronic control unit provided in an internal combustion engine detects a degree of inter-cylinder variation of the amount of fuel that is injected from a port injector, and a degree of inter-cylinder variation of the amount of fuel that is injected from an in-cylinder injector. In a case where the inter-cylinder variation of one of the port injector and the in-cylinder injector is equal to or greater than a predefined value, a process is executed of limiting, so as not to exceed an upper limit value, an injection proportion of the injector for which the inter-cylinder variation is equal to or greater than the predefined value. This upper limit value is set to be smaller as the degree of inter-cylinder variation of the injector, for which the inter-cylinder variation is equal to or greater than a predefined value, increases.

Abstract: A control apparatus for an internal combustion engine includes an electronic control unit. The electronic control unit corrects a target air-fuel ratio in an air-fuel ratio control with a first correction value set based on a degree of variation among cylinders in terms of a fuel amount to be injected from the port injector, and a second correction value set based on a degree of variation among the cylinders in terms of a fuel amount to be injected from the in-cylinder injector. A first correction amount of the target air-fuel ratio by the first correction value is set to be larger as an injection amount ratio of the intake-port fuel injection valve is larger, and a second correction amount of the target air-fuel ratio by the second correction value is set to be larger as an injection amount ratio of the in-cylinder fuel injection valve is larger.

Abstract: An electronic control unit executes air-fuel ratio control composed of main feedback correction and sub-feedback correction. The main feedback correction uses an output value of an upstream side sensor in upstream side of a catalyst. The sub-feedback correction uses an output value of a downstream side sensor in downstream side of the catalyst. When there are cylinder-to-cylinder variations in a fuel injection amount of each fuel injection valve, the electronic control unit corrects the fuel injection amount. Each time the degree of the cylinder-to-cylinder variations is lower than or equal to a first predetermined value, the electronic control unit stores the sub-learning value at that point in time as a normal value, and, when the degree of the cylinder-to-cylinder variations is higher than or equal to a second predetermined value, the electronic control unit changes the sub-learning value to the stored normal value.

Abstract: A fuel supply system for use with an internal combustion engine has a check valve and a purge valve disposed in a purge passage that extends from a canister to connect with an intake passage of the internal combustion engine. A controller regulates the purge valve open with a first opening degree or a first duty ratio during a purge operation. The controller may also regulate the purge valve to open with a second opening degree larger than the first opening degree or a second duty ratio larger than the first duty ratio a predetermined time after initiating the purge operation.