Abstract: A control device for an internal combustion engine performs rich control when a fuel cutoff operation is terminated and fuel supply to a combustion chamber is restarted, and the engine includes a plurality of the combustion chambers and a fuel supply cycle is repeated. The control device includes a controller configured to set a first moment and a second moment such that the fuel supply cycle which includes the first moment is different from the fuel supply cycle which includes the second moment, the first moment being a moment at which the rich control is started in a first combustion chamber of the plurality of combustion chambers, and the second moment being a moment at which the rich control is started in a second combustion chamber of the plurality of combustion chambers that is different from the first combustion chamber.

Abstract: An air-fuel ratio control apparatus of the present invention includes a determination section and a reverse direction correction introducing section. The determination section determines whether or not an output of the downstream air-fuel ratio sensor falls within a predetermined range whose center corresponds to a target value corresponding to the stoichiometric air-fuel ratio. When the output of the downstream air-fuel ratio sensor falls within the predetermined range, the reverse direction correction introducing section temporarily introduces, to an air-fuel ratio correction in a direction requested by the output, an air-fuel ratio correction in a direction opposite to the requested direction.

Abstract: It is an object of this invention to restrain blow-by gas from reaching a catalyst during fuel cutoff, and protect the catalyst while coping with an increase in oil dilution amount resulting from the use of alcohol fuel, in an internal combustion engine that uses the alcohol fuel. An engine is equipped with a PCV mechanism that introduces blow-by gas in a crankcase into an intake system. Besides, when fuel cutoff is executed with the PCV mechanism in operation, an opening degree of a throttle valve during fuel cutoff is set on the basis of an oil dilution amount in lubricating oil. Thus, the throttle opening degree during fuel cutoff is adjusted in accordance with a generation amount of blow-by gas, so that an intake negative pressure can be appropriately reduced. Accordingly, during fuel cutoff, the amount of blow-by gas that is sucked out from the crankcase due to the intake negative pressure and introduced into the intake system can be held small.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine according to an embodiment of the invention (the present control apparatus) sets a target air-fuel ratio to a target rich air-fuel ratio when it is determined on the basis of the output value Voxs of a downstream air-fuel ratio sensor 67 that the oxygen adsorption amount of a catalyst 43 tends to be excessive, and sets the target air-fuel ratio to a target lean air-fuel ratio when it is determined on the basis of the output value Voxs that the oxygen adsorption amount of the catalyst 43 tends to be insufficient. Further, the present control apparatus determines whether or not an operation state in which a large amount of nitrogen oxide flows into the catalyst 43 is reached on the basis of “whether a predetermined condition is fulfilled”, and makes the target rich air-fuel ratio obtained when the predetermined condition is fulfilled less than the target rich air-fuel ratio obtained when the predetermined condition is not fulfilled.

Abstract: The present invention provides an additive agent to be added to oil and comprising weak basic hydrotalcite. At the time of adding a mixture of hydrotalcite of 1 weight % and water by 3 weight % to the oil where a hydrogen ion exponent is within a range of 6 to 7 for stirring, the weak basic hydrotalcite is hydrotalcite where the obtained oil indicates the hydrogen ion exponent within a range of 6 to 7. Such an additive agent can be accommodated in an oil filter (36) for use.

Abstract: A air-fuel ratio control apparatus, applied to an internal combustion engine having a catalyst disposed in an exhaust passage of the engine, includes a downstream air-fuel ratio sensor (oxygen concentration cell type oxygen concentration sensor) disposed at a position downstream of the catalyst, and air-fuel ratio control means for controlling, based on an output value of the downstream air-fuel ratio sensor, an air-fuel ratio of a mixture supplied to the engine so as to change an air-fuel ratio of a catalyst inflow gas. Further, the air-fuel ratio control means controls the air-fuel ratio of the mixture supplied to the engine.

Abstract: Active air-fuel ratio control is performed to alternately control an air-fuel ratio in an area located upstream of a catalyst between a lean side and a rich side. Switching is carried out between lean control and rich control at the same time when an output from a post-catalyst sensor reaches a threshold. Whether the catalyst is normal or abnormal is determined based on the rate of a change in the output from the post-catalyst sensor between a first point of time when a pre-catalyst air-fuel ratio reaches stoichiometry after the output from the post-catalyst sensor reaches the threshold and a second point of time when the output from the post-catalyst sensor reaches the threshold next time.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine of the present invention determines whether or not a lean request has occurred, based on a comparison between a value correlating with an output value of the downstream air-fuel ratio sensor disposed downstream of the catalyst (downstream air-fuel ratio sensor output correlating value) and a predetermined lean request determining value, and determines whether or not a rich request has occurred, based on a comparison between the downstream air-fuel ratio sensor output correlating value and a predetermined rich request determining value. Further, the air-fuel ratio control apparatus calculates a total amount of oxygen (released oxygen amount) released from the catalyst in the rich request occurring period, and calculates an integrated value (present stored oxygen amount) of oxygen stored in the catalyst after a start of the lean request occurring period which follows the rich request occurring period.

Abstract: An air-fuel ratio control apparatus of the present invention includes a determination section and a reverse direction correction introducing section. The determination section determines whether or not an output of the downstream air-fuel ratio sensor falls within a predetermined range whose center corresponds to a target value corresponding to the stoichiometric air-fuel ratio. When the output of the downstream air-fuel ratio sensor falls within the predetermined range, the reverse direction correction introducing section temporarily introduces, to an air-fuel ratio correction in a direction requested by the output, an air-fuel ratio correction in a direction opposite to the requested direction.

Abstract: An air-fuel ratio control apparatus of the present invention comprises an inverse direction spike introducing section and an inverse direction spike interval setting section. The inverse direction spike introducing section introduces, while an air-fuel ratio correction required by an output of a downstream air-fuel ratio sensor is being carried out, an inverse direction spike which is an air-fuel ratio spike to temporarily change an air-fuel ratio of an exhaust gas toward a direction opposite to a direction of the air-fuel ratio correction with respect to a target control air-fuel ratio. The inverse direction spike interval setting section sets, based on an operating state of an internal combustion engine system, an inverse direction spike interval which is an interval between two of the inverse direction spikes next to each other in time.

Abstract: An embodiment (control apparatus) of an air-fuel ratio control apparatus according to the present invention determines, based on an output value Voxs of a downstream air-fuel ratio sensor 56 disposed at a position downstream of a three-way catalyst 43, which air-fuel request is occurring, a rich request or a lean request. The control apparatus sets an air-fuel ratio of each cylinder (cylinder-by-cylinder air-fuel ratio) to a rich air-fuel ratio when the rich request is occurring, and sets the cylinder-by-cylinder air-fuel ratio to a lean air-fuel ratio when the lean request is occurring.

Abstract: An exhaust passage of an internal combustion engine is provided with an upstream side three-way catalyst capable of purifying exhaust gas and a particulate filter (PM filter) for trapping particulate matter PM contained in exhaust gas. Catalyst warm-up control is exercised for the purpose of warming up mainly the upstream side three-way catalyst at cold start. Filter regeneration control for removing the particulate matter PM accumulating on the particulate filter from the filter is exercised at the cold start after the catalyst warm-up control is exercised.

Abstract: An ammonia burning internal combustion engine in which, in addition to ammonia, a reformed gas reformed at a reformer is fed into a combustion chamber. When a reforming ability of the reformer is less than a predetermined reforming ability, an ammonia ratio is increased to a ratio more than the ammonia ratio after completion of engine warmup set in advance in accordance with an operation state of the engine, and secondary air is fed from a secondary air feeding device into an engine exhaust passage upstream of an exhaust purification catalyst.

Abstract: An air-fuel ratio control apparatus according to an embodiment of the present invention, controls an air-fuel ratio (air-fuel ratio of an engine) of a mixture supplied to the engine, based on an output value of the downstream-side air-fuel ratio sensor disposed downstream of a catalyst. That is, the air-fuel ratio control apparatus sets the air-fuel ratio of the engine at a rich air-fuel ratio when the output Voxs is smaller than a reference value VREF (when a rich request is occurring). The air-fuel ratio control apparatus sets the air-fuel ratio of the engine at a lean air-fuel ratio when the output Voxs is larger than a reference value VREF (when a lean request is occurring). The air-fuel ratio control apparatus makes the target value VREF gradually come closer to a reference value VF (stoichiometric air-fuel ratio corresponding value) from a certain value, when the output value Voxs deviates greatly from the reference value Vf (points P1-P3).

Abstract: A control system of an internal combustion engine in which a first fuel of ammonia and a second fuel which is easier to burn than ammonia are used as fuels. An ammonia ratio is usually set to a reference ammonia ratio which is determined in advance in accordance with an operating state of an engine. At the time when feed of the fuel is restarted after suspension of feed of the fuel at the time of deceleration, the ammonia ratio is temporarily made lower than the reference ammonia ratio in accordance with the operating state of the engine.

Abstract: A control device for an internal combustion engine performs rich control when a fuel cutoff operation is terminated and fuel supply to a combustion chamber is restarted, and the engine includes a plurality of the combustion chambers and a fuel supply cycle is repeated. The control device includes a controller configured to set a first moment and a second moment such that the fuel supply cycle which includes the first moment is different from the fuel supply cycle which includes the second moment, the first moment being a moment at which the rich control is started in a first combustion chamber of the plurality of combustion chambers, and the second moment being a moment at which the rich control is started in a second combustion chamber of the plurality of combustion chambers that is different from the first combustion chamber.

Abstract: An air-fuel ratio control device includes an air-fuel ratio sensor provided upstream from a three-way catalyst, and an oxygen sensor provided downstream from the three-way catalyst. The air-fuel ratio control device controls the fuel supply amount based on the output from the air-fuel ratio sensor, and compensates for errors in the air-fuel ratio sensor by correcting the fuel supply amount based on the output from the oxygen sensor. The fuel supply correction amount is calculated based on an integral term that integrates the deviation between the output from the downstream air-fuel ratio sensor and the target air-fuel ratio. When a fuel supply adjustment control is executed, the value of the integral term in the sub-feedback control is not updated for a predetermined period after the fuel supply adjustment control ends. The actual air-fuel ratio is thus brought to the target air-fuel ratio in an appropriate manner.

Abstract: Active air-fuel ratio control is performed to alternately control an air-fuel ratio in an area located upstream of a catalyst between a lean side and a rich side. Switching is carried out between lean control and rich control at the same time when an output from a post-catalyst sensor reaches a threshold. Whether the catalyst is normal or abnormal is determined based on the rate of a change in the output from the post-catalyst sensor between a first point of time when a pre-catalyst air-fuel ratio reaches stoichiometry after the output from the post-catalyst sensor reaches the threshold and a second point of time when the output from the post-catalyst sensor reaches the threshold next time.

Abstract: In the present invention, in a control system for a spark ignition internal combustion engine, when a catalyst is not sufficiently active, the ignition timing is advanced to be earlier than MBT to decrease the quantity of hydrocarbons (HC) discharged from the internal combustion engine, and oxygen is supplied to the exhaust gas upstream of the catalyst to thereby oxidize carbon monoxide (CO) discharged from the internal combustion engine. According to this invention, exhaust emissions emitted before activation of the exhaust gas purification apparatus can be decreased as much as possible, and early activation of the catalyst can be achieved by making use of heat generated by oxidation reaction of carbon monoxide (CO).

Abstract: The present invention provides an additive agent to be added to oil and comprising weak basic hydrotalcite. At the time of adding a mixture of hydrotalcite of 1 weight % and water by 3 weight % to the oil where a hydrogen ion exponent is within a range of 6 to 7 for stirring, the weak basic hydrotalcite is hydrotalcite where the obtained oil indicates the hydrogen ion exponent within a range of 6 to 7. Such an additive agent can be accommodated in an oil filter (36) for use.