# US 10,320,155 B2 · Ignition device for internal combustion engine

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- Number: US 10,320,155 B2
- Document ID: US10320155B2
- Status: Granted
- Kind: B2
- Application number: 15/765,922
- Filed: 2015-11-12
- Published: 2018-10-25
- Granted: 2019-06-11
- Earliest claimed: 2015-11-12
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Takashi Idogawa
- Web page: https://patentgrep.com/patent/US10320155B2

## CPC

- H01T 13/04: Means providing electrical connection to sparking plugs
- F02P 3/02: having inductive energy storage, e.g. arrangements of induction coils {(ignition coils structurally combined with sparking plugs F02P13/00; constructional details of ignition coils H01F38/12)}
- F02P 3/04: Layout of circuits
- 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})
- H01F 38/12: Ignition, e.g. for IC engines
- H01T 13/44: with transformers, e.g. for high-frequency ignition
- H01T 13/50: having means for ionisation of gap (H01T13/52 takes precedence)
- 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)
- 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)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

This invention is concerning an ignition device for an internal combustion engine, wherein a plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of the other portion, a spring has a larger diameter portion having a diameter size larger than that of the other portion, and a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and the inner wall surface of the plug boot.

## Claims

### Claim 1

An ignition device for an internal combustion engine, the ignition device comprising:
an ignition coil having a primary coil, a secondary coil, an iron core magnetically coupling the primary coil and the secondary coil to each other, and an insulating case containing the primary coil, the secondary coil, and the iron core;
a high-voltage tower provided integrally with the insulating case and internally holding a high-voltage output terminal which outputs, to the outside of the ignition coil, a high voltage generated in the secondary coil when conduction of an excitation current flowing in the primary coil is interrupted;
a plug boot formed in a cylindrical shape and having an end portion attached to the high-voltage tower; and
an interposing member provided in the plug boot and having a spring that is formed in a coil shape and electrically connects, to the high-voltage output terminal, an ignition plug terminal of an ignition plug having a tip portion facing an inside of a cylinder of the internal combustion engine, wherein
the plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of another portion,
the reduced-inner-diameter portion is formed of a plurality of ribs protruding inwardly in a radial direction from the inner wall surface,
the spring has a larger diameter portion having a diameter size larger than that of another portion, and
a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and an inner wall surface of the plug boot.

### Claim 2 (depends on 1)

The ignition device for an internal combustion engine of claim 1, wherein at least one of a plurality of the larger diameter portions is formed of a closely wound coil.

### Claim 3 (depends on 2)

The ignition device for an internal combustion engine of claim 2, wherein a diameter of the larger diameter portion is larger than an inner diameter of the reduced-inner-diameter portion.

### Claim 4 (depends on 1)

The ignition device for an internal combustion engine of claim 1, wherein a diameter of the larger diameter portion is larger than an inner diameter of the reduced-inner-diameter portion.