A high-frequency filter includes a first terminal, a second terminal, a third terminal, a first inductor, a second inductor, a third inductor, and a fourth inductor. The first inductor and the second inductor are connected in series to each other between the first terminal and the second terminal. The third inductor and the fourth inductor are connected in parallel to each other between the third terminal and a node of the first inductor and the second inductor. The connection between the first inductor and the second inductor is an additive polarity connection. The connection between the third inductor and the fourth inductor is an additive polarity connection.

An ignition system for an internal combustion engine has a power source, a transformer having a first primary winding and a second primary winding and a secondary winding, a connector extending from the secondary winding so as to connect with a terminal of a spark plug, and a multi-strike circuit cooperative with the electronic spark timing circuit so as to fire the transformer with multiple strikes between the falling edge and the rising edge. A booster circuit is cooperative at the electronic spark timing circuit so as to collect and store energy from the power source while the electronic spark timing circuit fires the transformer. A delay circuit fires the transformer at a time subsequent to the falling edge and before the rising edge.

An ignition system for an internal combustion engine has a power source, a transformer having a first primary winding and a second primary winding and a secondary winding, a connector extending from the secondary winding so as to connect with a terminal of a spark plug, and a multi-strike circuit cooperative with the electronic spark timing circuit so as to fire the transformer with multiple strikes between the falling edge and the rising edge. A booster circuit is cooperative at the electronic spark timing circuit so as to collect and store energy from the power source while the electronic spark timing circuit fires the transformer. A delay circuit fires the transformer at a time subsequent to the falling edge and before the rising edge.

An ignition apparatus includes an ignition plug, a boost transformer, an ignition power source and a measurement unit. The ignition plug has a center electrode and a ground electrode. The boost transformer supplies the ignition plug with electric power generated in a secondary coil upon supply of AC power from the ignition power source to a primary coil. The measurement unit measures the discharge voltage of the ignition plug. The ignition power source includes a discharge state determining unit that determines the discharge state of the ignition plug based on the measured discharge voltage and a current controlling unit that controls electric current supplied to the primary coil. When a discharge path formed between the center and ground electrodes of the ignition plug is determined by the discharge state determining unit as being in an over-extended state, the current controlling unit reduces the electric current supplied to the primary coil.

The object is to provide an injector with a built-in ignition device that can achieve downsize of device as a whole without changing significantly the structure of a fuel injection device. The injector with the built-in ignition device comprises an ignition device 3 and a fuel injection device 2. In the ignition device 3, an electromagnetic wave oscillated from an electromagnetic wave oscillator MW is boosted by a booster that is constituted by a resonance structure, a potential difference between a ground electrode 51 and a discharge electrode 31 is increased, and a discharge is caused. In the fuel injection device 2, a valve body part of a nozzle needle 24 is moved toward or away from a valve seat (orifis) 23a, and thereby, the fuel injection control is performed. Then, the resonance structure is formed by a dielectric member 30 that is connected to the electromagnetic wave oscillator and formed on the surface of a fuel injection pipe 21, and an inner wall surface 50a of a mounting port 50 for an injector of a cylinder head 5. A discharge electrode 31 is a projection that is formed on the surface of the fuel injection pipe 21, and a discharge is caused by making a position of the wall surface of the mounting port 5 that is closest to the discharge electrode 31 as a ground electrode 51.

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 a general aspect, an ignition circuit can include a control circuit configured to receive a command signal from an engine control unit, and a driving circuit coupled with the control circuit. The driving circuit can be configured to be coupled with a resonant circuit that includes a primary winding of an ignition coil. The control circuit and the driving circuit can be configured, in response to a command signal, to drive the resonant circuit at a first frequency to generate a voltage in the ignition coil to initiate a spark in a spark plug; and, in response to the spark being initiated in the spark plug, drive the resonant circuit at a second frequency to maintain the spark in the spark plug for combustion of a fuel mixture. The control circuit can be configured to, after the combustion of the fuel mixture, to disable the driving circuit.

In a general aspect, an ignition circuit can include a control circuit configured to receive a command signal from an engine control unit, and a driving circuit coupled with the control circuit. The driving circuit can be configured to be coupled with a resonant circuit that includes a primary winding of an ignition coil. The control circuit and the driving circuit can be configured, in response to a command signal, to drive the resonant circuit at a first frequency to generate a voltage in the ignition coil to initiate a spark in a spark plug; and, in response to the spark being initiated in the spark plug, drive the resonant circuit at a second frequency to maintain the spark in the spark plug for combustion of a fuel mixture. The control circuit can be configured to, after the combustion of the fuel mixture, to disable the driving circuit.

Disclosed is an inventive method for controlling a corona ignition device of an internal combustion engine. A corona discharge, which ignites fuel in a combustion chamber of the engine, is generated by applying a voltage to the corona ignition device. An actual value that is characteristic of the nitrogen oxide concentration of the exhaust gas is compared with a setpoint value, and, if the actual value deviates from the setpoint value by more than a specified threshold value and the actual value is greater than the setpoint value, the voltage is reduced after the comparison.

A high-frequency filter includes a first terminal, a second terminal, a third terminal, a first inductor, a second inductor, a third inductor, and a fourth inductor. The first inductor and the second inductor are connected in series to each other between the first terminal and the second terminal. The third inductor and the fourth inductor are connected in parallel to each other between the third terminal and a node of the first inductor and the second inductor. The connection between the first inductor and the second inductor is an additive polarity connection. The connection between the third inductor and the fourth inductor is an additive polarity connection.