# US 10,772,184 B2 · Ignition device

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- Number: US 10,772,184 B2
- Document ID: US10772184B2
- Status: Granted
- Kind: B2
- Application number: 16/565,910
- Filed: 2019-09-10
- Published: 2020-03-12
- Granted: 2020-09-08
- Earliest claimed: 2018-09-12
- Assignees: Denso Corporation; Plasma Applications Co., Ltd.; Tokyo Keiki Co., Ltd.
- Applicants: Denso Corporation; Plasma Applications Co., Ltd.; Tokyo Keiki Inc.
- Inventors: Daisuke Tanaka; Fumiaki Aoki; Akimitsu Sugiura; Masashi Kando; Jan Husarik; Hiroshi Okajima
- Web page: https://patentgrep.com/patent/US10772184B2

## CPC

- H05H 1/52: using exploding wires or spark gaps (H05H1/26 takes precedence)
- F02M 57/06: the devices being sparking plugs
- F02P 3/01: Electric spark ignition installations without subsequent energy storage, i.e. energy supplied by an electrical oscillator (with magneto- or dynamo-electric generators F02P1/00; piezoelectric ignition F02P3/12; with continuous electric spark F02P15/10)
- F02P 13/00: 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})
- F02P 23/045: {using electromagnetic microwaves}
- H01T 13/32: characterised by features of the earthed electrode
- H01T 13/50: having means for ionisation of gap (H01T13/52 takes precedence)
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00)
- H01T: SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES (overvoltage protection circuits H02H)

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

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.

### Claim 4 (depends on 3)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

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.

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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.

### Claim 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.

### Claim 10 (depends on 9)

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.