Methods and systems are provided for controlling fueling and mitigating knock in internal combustion engines, such as multi-fuel engines. In one example, a method may include monitoring a frequency of knock events corresponding to one or more engine cylinders, and dynamically increasing a substitution ratio while the frequency of knock events is less than a maximum action threshold. In some examples, the method may further include actively adjusting one or more engine operating conditions to decrease the substitution ratio responsive to a severity of knocking in the one or more engine cylinders being greater than or equal to a threshold severity.

A multi-cylinder internal combustion engine is configured to perform an all-cylinder operation and a partial-cylinder operation. The ignition timing controller executes a process that sets a knock control amount and a knock learning value, a process that determines whether knocking is occurring, a process that updates a value of the knock control amount in accordance with whether knocking is occurring, a process that updates the knock learning value such that the knock learning value gradually approaches a knock control operated amount, a process that operates ignition timing of each cylinder based on the knock control amount and the knock learning value, and a process that limits update of the knock learning value such that a followability of the knock learning value to the knock control operated amount is lower during the partial-cylinder operation than during the all-cylinder operation.

A multi-cylinder internal combustion engine is configured to perform an all-cylinder operation and a partial-cylinder operation. The ignition timing controller executes a process that sets a knock control amount and a knock learning value, a process that determines whether knocking is occurring, a process that updates a value of the knock control amount in accordance with whether knocking is occurring, a process that updates the knock learning value such that the knock learning value gradually approaches a knock control operated amount, a process that operates ignition timing of each cylinder based on the knock control amount and the knock learning value, and a process that limits update of the knock learning value such that a followability of the knock learning value to the knock control operated amount is lower during the partial-cylinder operation than during the all-cylinder operation.

An ignition device of the present embodiment is an ignition device for an internal combustion and includes an ignition plug, an operating information acquisition unit and an ignition control unit. The ignition plug includes an accessory chamber and an injection hole from which flame is to be injected from the accessory chamber to a main combustion chamber. The operating information acquisition unit is configured to acquire operating information regarding an operating state of the internal combustion. The ignition control unit is configured to control an ignition energy profile that affects an ignition state of an air-fuel mixture based on the operating information acquired by the operating information acquisition unit.

An ignition device of the present embodiment is an ignition device for an internal combustion and includes an ignition plug, an operating information acquisition unit and an ignition control unit. The ignition plug includes an accessory chamber and an injection hole from which flame is to be injected from the accessory chamber to a main combustion chamber. The operating information acquisition unit is configured to acquire operating information regarding an operating state of the internal combustion. The ignition control unit is configured to control an ignition energy profile that affects an ignition state of an air-fuel mixture based on the operating information acquired by the operating information acquisition unit.

A combustion system is applied to an engine. The combustion system includes an injection device that injects a fuel into a combustion chamber, a spark plug that ignites fuel in the combustion chamber, and a control device that controls the injection device and the spark plug. The control device includes a first control unit that executes predetermined first control. In the first control, control is performed such that, a total injection amount corresponding to all the fuel injected by the injection device in one combustion cycle of the engine is injected within a first period corresponding to a period from valve close timing which brings an intake valve into a closed state until a first half of a compression stroke of the engine ends.

A combustion system is applied to an engine. The combustion system includes an injection device that injects a fuel into a combustion chamber, a spark plug that ignites fuel in the combustion chamber, and a control device that controls the injection device and the spark plug. The control device includes a first control unit that executes predetermined first control. In the first control, control is performed such that, a total injection amount corresponding to all the fuel injected by the injection device in one combustion cycle of the engine is injected within a first period corresponding to a period from valve close timing which brings an intake valve into a closed state until a first half of a compression stroke of the engine ends.

A method to control a road vehicle provided with an internal combustion engine having a plurality of cylinders and with a servo-assisted transmission. The control method comprises the steps of: establishing a minimum spark advance which should not be exceeded in order to avoid the risk of knocking or spontaneous ignitions of the mixture; temporarily reducing, during a gear shift in the servo-assisted transmission, a torque generated by the internal combustion engine by setting an actual spark advance, which is smaller than the minimum spark advance, for one single thermodynamic cycle of each cylinder; and cancelling the injection of fuel into each cylinder in the thermodynamic cycle immediately following the thermodynamic cycle carried out with an actual spark advance smaller than the minimum spark advance.

An ignition timing controller includes a storage and a processor configured or programmed to function as an ignition timing control section and a knocking determining section. The storage stores at least one of a first ignition timing map associated with a first fuel or a second ignition timing map associated with a second fuel more likely to cause knocking of an internal combustion engine than the first fuel. The ignition timing control section controls the ignition timing based on the first ignition timing map by executing a timing retardation based on the first ignition timing map when it is determined that knocking of the internal combustion engine has occurred. The ignition timing control section controls the ignition timing of the internal combustion engine based on the second ignition timing map by executing a timing advancement correction based on the second ignition timing map when it is determined that the knocking of the internal combustion engine has not occurred.

A combustion control system for an engine of a vehicle includes an ion sensing system configured to generate an ion current signal indicative of a measured current across electrodes of a spark plug associated with a cylinder of the engine and a controller configured to monitor for peaks in the ion current signal and, upon detecting at least a first peak and a second peak in the ion current signal, estimate a location of peak pressure (LPP) based on the detected second peak in the ion current signal, estimate an angle (CA50) of a crankshaft of the engine at which approximately 50% of the heat generated during combustion in the cylinder of the engine is released, and control combustion phasing of the engine based on the estimated CA50 angle.