Ignition device

Patent metadata

Field	Value
Publication number	US-10772184-B2
Application number	US-201916565910-A
Country	US
Kind code	B2
Filing date	Sep 10, 2019
Priority date	Sep 12, 2018
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

An ignition device ignites a mixture of air and fuel gas by plasma to generate an initial flame. The ignition device includes a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma. The ignition device includes an electromagnetic wave power supply that generates the electromagnetic wave by inputting the electromagnetic wave power Ps to the spark plug and a power supply control unit that controls the electromagnetic wave power supply. The electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies. The power supply control unit outputs at least one of the plurality of high frequency powers generated by the electromagnetic wave power supply as the electromagnetic wave power.

First claim

The invention claimed is:

1. An ignition device for igniting a mixture of air and fuel gas by plasma to generate an initial flame, comprising:
a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma;
an electromagnetic wave power supply that generates the electromagnetic wave and delivers an electromagnetic wave power to the spark plug; and
a power supply control unit that controls the electromagnetic wave power supply, wherein
the electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies,
the power supply control unit is configured to output at least one of the plurality of high frequency powers generated by the electromagnetic wave power supply as the electromagnetic wave power,
the electromagnetic wave power supply includes multiple oscillators that respectively generate high frequency power at a number of different frequencies, and
the electromagnetic wave power supply has a combiner configured to combine the high frequency power generated by the multiple oscillators, combines a plurality of the high, frequency powers in the combiner, and input it to the spark plug as the electromagnetic wave power.

2. The ignition device according to claim 1 , wherein
the power supply control unit adjusts the combined ratio of the plurality of high frequency powers in time series in one discharge cycle, and inputs it to the spark plug as the electromagnetic wave power.

3. The ignition device according to claim 2 , wherein
a first state that is a state in which plasma is not formed in the plasma formation space, a second state that is a state in which plasma is formed in the plasma formation space, and a third state is a state in which an initial flame is formed in the plasma formation space by plasma are states of the plasma formation space that sequentially change in time series in a short time during each discharge cycle.

4. The ignition device according to claim 3 , wherein
high frequency powers of three different frequencies are included in the electromagnetic wave power,
the three high frequency power frequencies have the frequency that matches the impedance in the first state, the frequency that matches the impedance in the second state and the frequency that matches in the third state.

5. The ignition device according to claim 1 , wherein
the power supply control unit switches a plurality of the high frequency powers in time series in one discharge cycle, and inputs it to the spark plug as the electromagnetic wave power.

6. The ignition device according to claim 1 , further comprising,
a reflected power detector configured to detect the reflected power from the spark plug, wherein
the power supply control unit adjusts a configuration of the high frequency power included in the electromagnetic wave power based on the reflected power by the reflected power detector.

7. The ignition device according to claim 1 , wherein the electromagnetic wave power is input to the spark plug from the combiner though an impedance transformation unit, the impedance transformation unit being configured to match an impedance of the electromagnetic wave power supply to an impedance of the plasma formation space.

8. The ignition device according to claim 1 , wherein the electromagnetic wave power is input to the spark plug from the combiner through an impedance transformation unit and a circulator, the impedance transformation unit being configured to match an impedance of the electromagnetic wave power supply to an impedance of the plasma formation space.

9. An ignition device for igniting a mixture of air and fuel gas by plasma to generate an initial flame, comprising:
a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma;
an electromagnetic wave power supply that generates the electromagnetic wave and delivers an electromagnetic wave power to the spark plug; and
a power supply control unit that controls the electromagnetic wave power supply, wherein
the electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies, and
the power supply control unit is configured to output at least one of the plurality of high frequency powers generated by the electromagnetic wave power supply as the electromagnetic wave power; wherein
the power supply control unit adjusts the combined ratio of the plurality of high frequency powers in time series in one discharge cycle, and inputs it to the spark plug as the electromagnetic wave power; and
a first state that is a state in which plasma is not formed in the plasma formation space, a second state that is a state in which plasma is formed in the plasma formation space, and a third state is a state in which an initial flame is formed in the plasma formation space by plasma are states of the plasma formation space that sequentially change in time series in a short time during each discharge cycle.

10. The ignition device according to claim 9 , wherein
high frequency powers of three different frequencies are included in the electromagnetic wave power,
the three high frequency power frequencies have the frequency that matches the impedance in the first state, the frequency that matches the impedance in the second state and the frequency that matches in the third state.

Assignees

• Denso Corp
• Plasma Applications Co Ltd
• Tokyo Keiki Inc

Inventors

• Tanaka Daisuke
• Aoki Fumiaki
• Sugiura Akimitsu
• Kando Masashi
• HUSARIK Jan
• Okajima Hiroshi

Classifications

• H05H1/52 Primary

  using exploding wires or spark gaps (H05H1/26 takes precedence) · CPC title

• F02P13/00

  Sparking plugs structurally combined with other parts of internal-combustion engines ({connection of ignition coil to spark plug connector F02P3/02;} with fuel injectors F02M57/06 {; spark plug connector per se H01T13/04 – H01T13/06; predominant aspects of sparking plug, see H01T13/40 – H01T13/44}) · CPC title

• F02P23/045

  using electromagnetic microwaves · CPC title

• H01T13/50

  having means for ionisation of gap (H01T13/52 takes precedence) · CPC title

• H01T13/32

  characterised by features of the earthed electrode · CPC title