# US 11,909,179 B2 · Spark plug and internal combustion engine equipped with the same

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- Number: US 11,909,179 B2
- Document ID: US11909179B2
- Status: Granted
- Kind: B2
- Application number: 18/175,172
- Filed: 2023-02-27
- Published: 2023-07-06
- Granted: 2024-02-20
- Earliest claimed: 2020-09-02
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Akimitsu Sugiura
- Web page: https://patentgrep.com/patent/US11909179B2

## CPC

- H01T 13/54: having electrodes arranged in a partly-enclosed ignition chamber
- F02B 19/08: the chamber being of air-swirl type
- F02B 19/12: with positive ignition (engines with non-timed positive ignition, and with incandescent chambers F02B9/08)
- F02B 19/18: Transfer passages between chamber and cylinder
- 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})
- H01T 13/20: characterised by features of the electrodes or insulation
- H01T 13/32: characterised by features of the earthed electrode
- Y02T 10/12: Improving ICE efficiencies
- 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)
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

In a spark plug, at least one injection hole serves as a ground-directed injection hole arranged to face a facing side of a ground electrode. An extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point. The facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is. The closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug. The predetermined angle being an obtuse angle.

## Claims

### Claim 1

A spark plug for an internal combustion engine, the spark plug having an axial direction and comprising:
a tubular insulator having a tip-side end;
a center electrode having one side and a tip-side end, the center electrode being disposed inside the insulator with the tip-side end of the center electrode protruding outwardly from the tip-side end of the insulator;
a tubular housing that has a tip-side end and retains the insulator thereinside;
a ground electrode having a stationary end and a projection-end edge opposite to the stationary end, and one side; and
a plug cover mounted to the tip-side end of the housing to define a sub-chamber between the plug cover and the tip-side end of the housing,
wherein:
the stationary end of the ground electrode is mounted to the tip-side end of the housing;
the projection-end edge of the ground electrode projects to be located in the sub-chamber such that the one side of the ground electrode serves as a facing side facing the one side of the center electrode, resulting in a discharge gap being formed between the facing side of the ground electrode and the one side of the center electrode;
the plug cover has formed therethrough at least one injection hole that enables the sub-chamber to communicate with an outside thereof, the at least one injection hole having a center axis;
the center axis of the at least one injection hole is inclined with respect to a radial direction of the spark plug as viewed in the axial direction of the spark plug;
the at least one injection hole serves as a ground-directed injection hole arranged to face the facing side of the ground electrode, and an extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point;
the facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is; and
the closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug, the predetermined angle being an obtuse angle.

### Claim 2 (depends on 1)

The spark plug according to claim 1, wherein:
the facing side of the ground electrode has one of a flat surface and an inwardly concave surface; and
the intersection point is located on one of the flat surface and the inwardly concave surface of the facing side.

### Claim 3 (depends on 1)

The spark plug according to claim 1, wherein:
the stationary end of the ground electrode is arranged on an opposite side of the center electrode from the projection-end edge of the ground electrode as viewed in a facing direction in which the ground electrode is aligned to face the center electrode.

### Claim 4 (depends on 1)

The spark plug according to claim 1, wherein:
the at least one injection hole comprises a plurality of injection holes formed through the plug cover, one of the plurality of injection holes serving as the ground-directed injection hole;
each of the plurality of injection holes has an inner diameter; and
the inner diameter of the ground-directed injection hole is greater than the inner diameter of each of the plurality of injection holes except for the ground-directed injection hole.

### Claim 5 (depends on 1)

An internal combustion engine comprising:
a main chamber;
a spark plug according to claim 1, the plug cover having an outer peripheral surface, the spark plug being arranged such that the outer peripheral surface of the plug cover is exposed in the main chamber; and
an injector configured to directly spray fuel in the main chamber, wherein:
the spark plug is arranged such that a fuel-containing flow including the fuel sprayed from the injector during a compression stroke of the internal combustion engine is directed toward an outer opening of the ground-directed injection hole.

### Claim 6 (depends on 1)

An internal combustion engine comprising:
a main chamber; and
a spark plug according to claim 1, the plug cover having an outer peripheral surface, the spark plug being arranged such that the outer peripheral surface of the plug cover is exposed in the main chamber, wherein:
the spark plug is arranged such that an outer opening of the ground-directed injection hole is directed toward an upstream side of an airflow formed in the main chamber.

### Claim 7 (depends on 1)

The spark plug according to claim 1, wherein:
the at least one injection hole comprises a plurality of injection holes formed through the plug cover, one of the plurality of injection holes serving as the ground-directed injection hole; and
an inner-diameter of the ground-directed injection hole is 1.2 to 1.4 times more than the inner diameter of each of the other injection holes.

### Claim 8 (depends on 1)

The spark plug according to claim 1, wherein:
the at least one injection hole comprises a plurality of injection holes formed through the plug cover; one of the plurality of injection holes serving as the ground-directed injection hole; and
the extension line of the center axis of each of the plurality of injection holes extends while not passing through the center electrode.

### Claim 9 (depends on 1)

The spark plug according to claim 1, wherein:
the at least one injection hole comprises a plurality of injection holes formed through the plug cover one of the plurality of injection holes serving as the ground-directed injection hole;
as viewed in the axial direction, an extension line of the center axis of each of the injection holes is inclined by an acute angle with respect to a virtual line that is defined to extend in the radial direction of the spark plug while passing through the plug center axis and any injection hole; and
the acute angle made between the extension line of the center axis of each of the injection holes and the corresponding virtual line is set to a constant acute angle.

### Claim 10 (depends on 1)

The spark plug according to claim 1, wherein the predetermined angle is more than or equal to 120 degrees as view in the axial direction.

### Claim 11 (depends on 1)

The spark plug according to claim 1, wherein:
a direction in which the facing side of the ground electrode is aligned to face the tip-side end of the center electrode is a facing direction; and
as viewed in the facing direction, the intersection point is located to be closer to the stationary end of the ground electrode than the center electrode is.

### Claim 12 (depends on 1)

The spark plug according to claim 1, wherein:
a direction in which the facing side of the ground electrode is aligned to face the tip-side end of the center electrode is a facing direction; and
as viewed in the facing direction, a length of the shortest distance between the intersection point and the center electrode is smaller than the diameter of the center electrode.

### Claim 13 (depends on 1)

The spark plug according to claim 1, wherein:
a direction in which the facing side of the ground electrode is aligned to face the tip-side end of the center electrode is a facing direction; and
as viewed in the facing direction, the intersection point is located to overlap with the center electrode at least partially.

### Claim 14 (depends on 1)

The spark plug according to claim 1, wherein:
a direction in which the facing side of the ground electrode is aligned to face the tip-side end of the center electrode is a facing direction; and
as viewed in the facing direction, the intersection point is located to be closer to the projection-end edge of the ground electrode than the center electrode is.