A high-frequency discharge ignition device includes a current supply device which supplies an AC current to a spark discharge path formed in a gap of an ignition plug, a control device which controls the operation of the current supply device, and a voltage detection device which outputs a signal of a section where a magnetic induction voltage of a primary coil generated after a switch element of an ignition coil device is placed in a shutoff state exceeds a predetermined voltage, and the control device determines the timing when the spark discharge path has been formed in the gap of the ignition plug according to an output signal of the voltage detection device and operates the current supply device based on the timing when the spark discharge path has been formed in the gap of the ignition plug to supply the AC current to the spark discharge path.

A small-size injector having a built-in ignition device which can surely inject fuel and ignite the fuel with low electric power by the ignition device with a simple configuration is provided. The injector comprises a fuel injecting device 2 having a fuel injecting port 20 that injects the fuel, an ignition device 3 configured to ignite the injected fuel, and a casing 10 inside housing therein the fuel injecting device 2 and the ignition device 3 together. The motion device 3 is constituted of a plasma generator 3 which integrally comprises a booster 5 having a resonation structure capacity-coupled with an electromagnetic wave oscillator MW configured to oscillate an electromagnetic wave, and a discharger 6 configured to cause a discharge of a high voltage generated by the booster 5.

A small-size injector having a built-in ignition device which can surely inject fuel and ignite the fuel with low electric power by the ignition device with a simple configuration is provided. The injector comprises a fuel injecting device 2 having a fuel injecting port 20 that injects the fuel, an ignition device 3 configured to ignite the injected fuel, and a casing 10 inside housing therein the fuel injecting device 2 and the ignition device 3 together. The motion device 3 is constituted of a plasma generator 3 which integrally comprises a booster 5 having a resonation structure capacity-coupled with an electromagnetic wave oscillator MW configured to oscillate an electromagnetic wave, and a discharger 6 configured to cause a discharge of a high voltage generated by the booster 5.

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 device includes a spark plug, a measurement value detector, an electrical breakdown determiner, an AC voltage applying section, and a first changing section. The measurement value detector includes primary and secondary coils, and detects at least one measurement value among an ignition coil, a primary current, a primary voltage, a secondary current, and a secondary voltage. The electrical breakdown determiner determines whether a discharge has become an electrical breakdown state based on the measurement value. The AC voltage applying section applies an AC voltage of a first predetermined frequency that causes voltage resonance to the primary coil. The first changing section changes the frequency of the AC voltage to a second predetermined frequency that can maintain the electrical breakdown state and is lower in frequency than the first predetermined frequency when it is determined that the discharge has become the electrical breakdown state.

A small-size injector having a built-in ignition device which can surely inject fuel and ignite the fuel with low electric power by the ignition device with a simple configuration is provided. The injector comprises a fuel injecting device 2 provided with a fuel injecting port 20 configured to inject the fuel, an ignition device 3 configured to ignite the injected fuel, and a casing 10 inside housing therein the fuel injecting device 2 and the ignition device 3 together. The ignition device 3 is constituted of a plasma generator 3 which integrally comprises a booster 5 having a resonation structure capacity-coupled with an electromagnetic wave oscillator MW configured to oscillate an electromagnetic wave, and a discharger 6 configured to cause a discharge of a high voltage generated by the booster 5.

An ignition device is provided, which can boost an electromagnetic wave supplied by a resonance structure, and cause a discharge by enhancing a potential difference between a discharge electrode and a ground electrode, and even though such a structure of the ignition device, a downsize and a thickness reduction, specifically, the thickness reduction can be achieved. On a main surface of a rectangular insulting substrate (2), an input electrode (3), a coupling electrode (4), a discharge electrode (6), and a ground electrode (7), are provided. The input electrode (3) is connected to an outside terminal on one shorter side. The coupling electrode (4) is capacity-coupled with the input electrode (3). The discharge electrode (6) is connected to the coupling electrode (4) on the other shorter side through a coupling line (5). The ground electrode (7) is, on both longer sides of the main surface of the rectangular insulating substrate (2), capacity-coupled with the coupling electrode (4) and capacity-coupled with the coupling line (5), and extended to the other shorter side. A resonance circuit includes a capacitor constituted by the capacity coupling and an inductor constituted by the coupling line (5). Thereby, the electromagnetic wave supplied from the outside terminal into the input electrode is resonated, a potential difference between the discharge electrode (6) and the ground electrode (7) is enhanced, and then, a discharge is caused.

An injector unit that can use a gaseous fuel such as CNG in an already-existing diesel engine and a spark plug that uses the injector unit, are provided. The injector unit includes an injector, an igniter having a resonance structure configured to boost an inputted microwave and a discharger configured to perform a discharge, and a casing configured to house therein the injector and the igniter. The igniter includes a first part configured to transmit the inputted microwave, a second part configured to perform a capacity coupling to attain an impedance matching between the microwave and the igniter, and a third part configured to transmit the capacity-coupled microwave to the discharger. Moreover, the igniter is bent at a boundary of the first part and the second part, a boundary of the second part and the third part, or inside the first part.

An injector unit that can use a gaseous fuel such as CNG in an already-existing diesel engine and a spark plug that uses the injector unit, are provided. The injector unit includes an injector, an igniter having a resonance structure configured to boost an inputted microwave and a discharger configured to perform a discharge, and a casing configured to house therein the injector and the igniter. The igniter includes a first part configured to transmit the inputted microwave, a second part configured to perform a capacity coupling to attain an impedance matching between the microwave and the igniter, and a third part configured to transmit the capacity-coupled microwave to the discharger. Moreover, the igniter is bent at a boundary of the first part and the second part, a boundary of the second part and the third part, or inside the first part.

In a method for creating a spark across a spark gap, in particular for igniting a flammable liquid to measure its flash point, by means of a spark generator which comprises an ignition transformer, wherein the spark generator, on the primary side of the ignition transformer, comprises at least one DC voltage source and, on the secondary side of the ignition transformer, comprises two electrodes delimiting the spark gap to be formed, wherein voltage pulses from the DC voltage source are applied to the ignition transformer on the primary side thereof, which voltage pulses generate ignition voltage pulses on the secondary side, the ignition transformer is operated in a first phase according to the flyback converter principle and in a subsequent, second phase according to the forward converter principle.