An ignition control system is applied to an internal combustion engine having an ignition coil, a switching element and a measurement detection part which detects at least one of a primary and a secondary voltages and a secondary current. The ignition coil has a primary coil and a secondary coil. The switching element performs conduction and interruption the primary current to the primary coil. The ignition control system has a primary current control unit generating a spark discharge at the ignition plug by passing the primary current through the primary coil, and perform interruption of the primary current, and a discharge short-circuiting determination part determining a generation of discharge short-circuiting based on a measured value. The primary current control unit generates the spark discharge again when discharge short-circuiting occurs.

A control unit according to the present invention performs an automatic stop control in which an injection of fuel from a fuel injection valve is stopped to stop a rotation of an engine when an automatic stop condition is satisfied. Furthermore, the control unit performs a first injection, in which fuel is injected from the fuel injection valve of a cylinder in an expansion stroke, and an ignition operation for igniting the fuel injected by the first injection, when a restart demand occurs after an initiation of the automatic stop control. In addition, the control unit performs a second injection, in which fuel is injected from the fuel injection valve of a cylinder in a compression stroke, and an ignition operation for igniting the fuel injected by the second injection. Then, the control unit performs a third injection, in which fuel is injected from the fuel injection valve of a cylinder in a compression stroke, when it judges that a start-up failure for which a crank angle of the cylinder which is in the compression stroke after the second injection cannot get over the compression top dead center occurs or will occur.

A system and method for detecting resonant frequency of a corona igniter concurrent with operation of the corona igniter is provided. The method includes providing a plurality of pulses of energy to the corona igniter, each having a pulse duration and spaced from one another by a deadtime duration during which no energy is provided to the corona igniter. Each pulse duration is ceased before current flowing in the corona igniter crosses zero, and each zero crossing of the current occurs during one of the deadtime durations. The next pulse of energy is provided to the corona igniter in response to the zero crossing of the current. A resonant frequency value is then obtained based on a sum of the pulse and deadtime durations of two consecutive cycles, or the time between zero crossings. The resonant frequency values become more accurate over time, and the drive frequency is adjusted accordingly.

An ignition system and a method for controlling an ignition system for a spark-ignited internal combustion engine are described, having a primary voltage generator for generating an ignition spark and a boost converter for maintaining an ignition spark. The method includes sending a signal from an engine control unit to the ignition system, in order to determine a predetermined ignition timing for triggering an ignition spark, sending an additional signal from the engine control unit to the ignition system, in order to determine a predetermined additional ignition timing for triggering an additional ignition spark, and sending a control signal for influencing the operating mode of the boost converter from the engine control unit to the ignition system between the signal and the additional signal.

A corona ignition system including a corona igniter, an energy supply, and a frequency detector is provided. The energy supply provides energy to the corona igniter during corona events which are spaced from one another by idle periods, during which no energy is provided to the corona igniter. During the idle periods, the frequency detector obtains the resonant frequency of the corona igniter from at least one of an output voltage and an output current of the energy stored in the corona igniter. The resonant frequency measured during this idle period is dependent only on the corona igniter, and not any other components of the system, and thus is very accurate. The drive frequency of future corona events can then be set based on this accurately measured resonant frequency to achieve a robust corona discharge.

An ignition device for an internal combustion engine has an ignition coil disposed as a transformer, a spark plug connected to the secondary winding of the ignition coil, an actuatable switching element connected in series with the primary winding of the ignition coil, and a control unit connected to the primary winding and to the control input of the switching element. After charging the ignition coil, building up an ignition spark through non-conductive switching of the switching element, and after renewed conductive switching of the switching element for operating the ignition coil in transformer operation, the supply voltage of the control unit is detected and if a pre-determined value, representing the presence of a surface gap, is exceeded, the switching element is once more switched non-conductive.

To reduce the amount of exhausted unburned fuel and further improve fuel efficiency of an internal combustion engine 10 provided with an ignition device 12 that ignites fuel air mixture more forcefully than a spark discharge in a combustion chamber 20. The internal combustion engine 10 includes an internal combustion engine main body 11 formed with the combustion chamber 20 and the ignition device 12 that ignites the fuel air mixture more forcefully than the spark discharge in the combustion chamber 20. In addition, the internal combustion engine 10 includes an electromagnetic wave emission device 13 that emits an electromagnetic wave supplied from an electromagnetic wave oscillator 32 from an antenna 41. The electromagnetic wave emission device 13 emits the electromagnetic wave from the antenna 41, thereby creating an electric field for accelerating a propagation speed of a flame.

An ignition apparatus performs energy input control in which energy is continuously inputted to an ignition coil to enable a spark discharge in a predetermined energy input period after interrupting a primary current by an ignition switch and generating a discharge of a spark plug by a secondary current. A combustion state determination circuit determines a combustion state by comparing a combustion pressure P detected by a combustion state detector. When the combustion pressure P is smaller than a second threshold Pth2, and there is room for improving the combustion state with respect to the present energy input condition, the energy input period IGW is increased or a target secondary current I2* is increased. By compensating the condition of the energy input control in accordance with the combustion state, a target combustion state can be achieved with just enough energy consumption.

The ignition system (10) of an engine (particularly for a UAV) has a primary (10a), and a secondary (10b) ignition system to provide redundancy for get you home capability should the primary ignition system fail. The secondary ignition provides a lower energy or shorter duration spark than the higher energy or longer duration sparking of the primary ignition system, and is retarded relative to primary sparking. Timing of the secondary sparking can be advanced in the event of primary sparking failure. Fuelling strategy can be shifted from a leaner stratified charge to a richer homogenous charge when relying just on the secondary ignition system for ignition. The secondary ignition system can be of a lower spark energy and/or duration than the primary ignition system, avoiding the cost, complexity and weight of replicating the primary ignition system, and to improve packaging within the engine housing, particularly within the limited payload and space limits of a UAV.

An ignition coil includes a circuit which generates a spark-generating current; a case within which the circuit is disposed; and a mounting boss attached to the case such that the mounting boss is rotatable relative to the case about a mounting boss axis, the mounting boss being configured to mount the ignition coil.