Abstract: An internal combustion engine is provided with a fuel injector which injects fuel into an intake port and exhaust variable valve timing mechanism which changes a valve timing of an exhaust valve. A control device executes early exhaust valve closing control which advances a closing timing of an exhaust valve when conditions for executing early exhaust valve closing control stand. The control device detects an output torque output by an engine body. At the time of deceleration of the engine, even when the condition for executing early exhaust valve closing control stands, execution of early exhaust valve closing control is prohibited when it is predicted that the output torque will become smaller than the limit torque. Thus, due to execution of the early exhaust valve closing control, a large torque fluctuation is prevented from occurring at the time of deceleration of the engine.

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: An ignition control system for a spark ignition internal combustion engine has: over-advancing means for over-advancing an ignition time for a cylinder of the internal combustion engine beyond an MBT; obtaining means for obtaining an adhering fuel amount that is the amount of fuel that adheres to the inner face of the cylinder of the internal combustion engine; and controlling means for controlling the over-advancing means to execute the ignition time over-advancement when the adhering fuel amount obtained by the obtaining means is equal to or larger than a predetermined amount.

Abstract: An internal combustion engine, including an air/fuel ratio sensor in an exhaust passage detecting an air/fuel ratio in a heated state, implements a technique improving emission at a starting time, by eliminating splash of water droplets early in the exhaust passage at the starting time to advance the heating starting timing of the air/fuel ratio sensor. At the starting time, opening/closing timing of a valve is advanced from a reference opening/closing timing or the reference of the opening/closing timing of the exhaust valve after the warming-up was ended, which continues until the wall temperature of the exhaust passage near the air/fuel ratio sensor becomes equal to or higher than a water droplet disappearing temperature, at which water droplets disappear. Then, change of the opening/closing timing of the exhaust valve responding to the running state by a variable valve mechanism is started.

Abstract: An internal combustion engine is provided with a fuel injector which injects fuel into an intake port and exhaust variable valve timing mechanism which changes a valve timing of an exhaust valve. A control device executes early exhaust valve closing control which advances a closing timing of an exhaust valve when conditions for executing early exhaust valve closing control stand. The control device includes a torque detecting means which detects an output torque output by an engine body. At the time of deceleration of the engine, even when the condition for executing early exhaust valve closing control stands, execution of early exhaust valve closing control is prohibited when it is predicted that the output torque will become smaller than the limit torque. Thus, due to execution of the early exhaust valve closing control, a large torque fluctuation is prevented from occurring at the time of deceleration of the engine.

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: An internal combustion engine, including an air/fuel ratio sensor in an exhaust passage detecting an air/fuel ratio in a heated state, implements a technique improving emission at a starting time, by eliminating splash of water droplets early in the exhaust passage at the starting time to advance the heating starting timing of the air/fuel ratio sensor. At the starting time, opening/closing timing of a valve is advanced from a reference opening/closing timing or the reference of the opening/closing timing of the exhaust valve after the warming-up was ended, which continues until the wall temperature of the exhaust passage near the air/fuel ratio sensor becomes equal to or higher than a water droplet disappearing temperature, at which water droplets disappear. Then, change of the opening/closing timing of the exhaust valve responding to the running state by a variable valve mechanism is started.

Abstract: An ignition control system for a spark ignition internal combustion engine has: over-advancing means for over-advancing an ignition time for a cylinder of the internal combustion engine beyond an MBT; obtaining means for obtaining an adhering fuel amount that is the amount of fuel that adheres to the inner face of the cylinder of the internal combustion engine; and controlling means for controlling the over-advancing means to execute the ignition time over-advancement when the adhering fuel amount obtained by the obtaining means is equal to or larger than a predetermined amount.

Abstract: A malfunction diagnostic apparatus for a combustion improvement device that is disposed in an intake passage connected to each of combustion chambers in an internal combustion engine to improve a combustion state, includes a detector that detects an average crank angular acceleration or a correlated value correlated with the average crank angular acceleration in each of cylinders in the internal combustion engine; an operating state detector that detects a current operating state of the combustion improvement device; and a malfunction determination device that determines whether a malfunction occurs in the combustion improvement device for each of the cylinders, based on the average crank angular acceleration or the correlated value and the current operating state of the combustion improvement device.

Abstract: In an ignition control system for an internal combustion engine which is capable of advancing the ignition timing beyond the MBT, the amount of fuel used for the combustion in a cylinder is made appropriate by performing a decreasing correction of the amount of fuel injection of a fuel injection valve when the ignition timing is advanced beyond the MBT.

Abstract: A malfunction diagnostic apparatus for a combustion improvement device that is disposed in an intake passage connected to each of combustion chambers in an internal combustion engine to improve a combustion state, includes a detector that detects an average crank angular acceleration or a correlated value correlated with the average crank angular acceleration in each of cylinders in the internal combustion engine; an operating state detector that detects a current operating state of the combustion improvement device; and a malfunction determination device that determines whether a malfunction occurs in the combustion improvement device for each of the cylinders, based on the average crank angular acceleration or the correlated value and the current operating state of the combustion improvement device.