An ignition device includes an ignition coil, an ignition plug and ignition control unit. The ignition control unit includes a secondary current adjusting unit that adjusts, in each cycle, an amount of the secondary current after initiating the discharge, a discharge extension detecting unit that detects an amount of extension of the discharge, and a short determination unit that determines whether a discharge-short has occurred. The ignition control unit controls the secondary current control unit such that a first step and a second step are repeatedly executed. The first step decreases the secondary current while keeping the secondary current higher than a predetermined lower current limit, when the extension amount detected by the discharge extension detecting unit is a predetermined extension amount or more. The second step increases the secondary current when the short determination unit determines that a discharge-short has occurred.

The return circuit of the ignition device returns to the battery the current supplied to the primary coil by the operation of the second circuit, and the voltage detection unit detects the voltage VB. The operation stopping unit monitors the voltage VB and when it is determined that the voltage VB is excessive, that is, when the voltage VB exceeds the threshold voltage VBc, it stops the supply of energy by the second circuit. As a result, when a load dump state occurs, the supply of energy by the second circuit can be stopped. Thus, when a load dump state occurs by the operation of the second circuit, other devices can be protected from overvoltage.

The return circuit of the ignition device returns to the battery the current supplied to the primary coil by the operation of the second circuit, and the voltage detection unit detects the voltage VB. The operation stopping unit monitors the voltage VB and when it is determined that the voltage VB is excessive, that is, when the voltage VB exceeds the threshold voltage VBc, it stops the supply of energy by the second circuit. As a result, when a load dump state occurs, the supply of energy by the second circuit can be stopped. Thus, when a load dump state occurs by the operation of the second circuit, other devices can be protected from overvoltage.

An ignition apparatus for internal combustion engines is provided. The ignition apparatus is equipped with an ECU. The ECU monitors a path length of a discharge of a spark for a period of time in which a second circuit delivers or inputs energy in the form of a threshold value determination. When the path length has become too short, the ECU determines that ignition is expected to be delayed and then selects a special mode to control the delay of the ignition. The ECU increase a target value of an energy input amount. This enables the delay of ignition resulting from a short extension of the path length to be minimized. The ignition apparatus equipped with the second circuit to continue the discharge of sparks is, thus, capable of reducing a variation in ignition without the need for uniformly increasing the energy input amount.

An ignition apparatus for an internal combustion engine is provided. The ignition apparatus includes an ECU. The ECU calculates a target value E* of an energy input amount of energy inputted into a spark plug based on an in-cylinder flow velocity v, a cylinder pressure P, and an air-fuel ratio AFR. The ECU also calculates a command value I* of a secondary current based on the in-cylinder flow velocity and control an operation of a second circuit according to the target value E* and the command value I*. The calculation of the target value E* using the in-cylinder flow velocity v, the cylinder pressure P, and the air fuel ratio AFR enables the energy input amount to be controlled according to the operating state of the internal combustion engine. The calculation of the command value I* based on the in-cylinder flow velocity v enables the secondary current to be controlled so as to eliminate a risk of the blowout of sparks. The ignition apparatus is, thus, capable of variably changing the amount of energy inputted to the spark plug to improve the fuel consumption.

When an abnormality judgement section judges that there is a failure of an energy inputting circuit, an energy inputting line, through which electrical energy is inputted from the energy inputting circuit to a primary winding, is changed over to a disconnected state by output halt switching means. As a result, since inputting of electrical energy to the primary winding is thereby halted, problems arising due to continuation of inputting electrical energy to the energy inputting circuit can be prevented, even in the event of a failure of the energy inputting circuit, so that reliability can be enhanced.

An ignition device includes an ignition coil, an ignition plug and ignition control unit. The ignition control unit includes a secondary current adjusting unit that adjusts, in each cycle, an amount of the secondary current after initiating the discharge, a discharge extension detecting unit that detects an amount of extension of the discharge, and a short determination unit that determines whether a discharge-short has occurred. The ignition control unit controls the secondary current control unit such that a first step and a second step are repeatedly executed. The first step decreases the secondary current while keeping the secondary current higher than a predetermined lower current limit, when the extension amount detected by the discharge extension detecting unit is a predetermined extension amount or more. The second step increases the secondary current when the short determination unit determines that a discharge-short has occurred.

An ignition control apparatus for engines is provided. The ignition control apparatus is designed to control a switch to release energy stored in a capacitor during spark discharge, thereby supplying a primary current to an other end side opposite a one end of a primary winding of an ignition coil connected to a dc power supply. This provides the ignition control apparatus which is capable of minimizing an increase in size or manufacturing cost and stabilizing the state of combustion of an air-fuel mixture.

An ignition control apparatus for engines is provided. The ignition control apparatus is designed to control a switch to release energy stored in a capacitor during spark discharge, thereby supplying a primary current to an other end side opposite a one end of a primary winding of an ignition coil connected to a dc power supply. This provides the ignition control apparatus which is capable of minimizing an increase in size or manufacturing cost and stabilizing the state of combustion of an air-fuel mixture.

In an ignition device, a second circuit energizes a primary coil from its negative side in a first direction to thereby maintain energization of a second coil in a second direction during spark discharge started by a first circuit. The maintained energization continuously supplies energy to a spark plug, thus performing a continuation of the spark discharge. The first direction is opposite to a direction of energization of the primary coil carried out by the first circuit, and the second direction is the same as a direction of energization of the second coil that has been started based on the first circuit. A humidity detection unit detects humidity of intake air into an engine. The control section controls the first circuit to advance start timing of the spark discharge generated by the first circuit in accordance with an increase in the humidity of the intake air.