# US 12,191,638 B2 · Prechamber spark plug having improved ignition properties

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- Number: US 12,191,638 B2
- Document ID: US12191638B2
- Status: Granted
- Kind: B2
- Application number: 18/571,350
- Filed: 2022-06-22
- Published: 2024-08-22
- Granted: 2025-01-07
- Earliest claimed: 2021-06-28
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Matthias Blankmeister; Thomas Steidten
- Web page: https://patentgrep.com/patent/US12191638B2

## CPC

- H01T 13/54: having electrodes arranged in a partly-enclosed ignition chamber
- H01T 13/16: Means for dissipating heat
- H01T 21/02: of sparking plugs
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A prechamber spark plug. The prechamber spark plug includes a housing having an external thread with a start of thread, a central electrode and a ground electrode, the central electrode and the ground electrode being arranged in a prechamber, and a cap that closes the prechamber in the direction of a combustion chamber, through-holes for a connection between the prechamber and an outer side of the prechamber spark plug being configured in the housing.

## Claims

### Claim 1

A prechamber spark plug, comprising:
a housing having an external thread with a start of thread;
a central electrode and a ground electrode, wherein the central electrode and the ground electrode are arranged in a prechamber; and
a cap closing the prechamber towards a combustion chamber;
wherein through-holes are configured in the housing for a connection between the prechamber and an outer side of the prechamber spark plug,
wherein each of the through-holes is disposed at a different angle to a center axis of the prechamber spark plug relative to one another.

### Claim 2 (depends on 1)

The prechamber spark plug according to claim 1, wherein the cap is configured as a flat cap and is configured flat to the outer side of the prechamber spark plug.

### Claim 3 (depends on 1)

The prechamber spark plug according to claim 1, wherein the housing is formed integrally with a threaded region having the external thread and a non-threaded region, wherein the non-threaded region adjoins the threaded region towards the combustion chamber, and wherein the through-holes are formed in the non-threaded region.

### Claim 4 (depends on 3)

The prechamber spark plug according to claim 3, wherein: (i) the non-threaded region has a lesser wall thickness than a wall thickness of the threaded region, or (ii) the non-threaded region has an equal or greater wall thickness than the wall thickness of the threaded region.

### Claim 5 (depends on 3)

The prechamber spark plug according to claim 3, wherein the through-holes are arranged at an obtuse angle to the center axis of the prechamber spark plug.

### Claim 6 (depends on 2)

The prechamber spark plug according to claim 2, wherein the cap is a flat disc.

### Claim 7 (depends on 1)

The prechamber spark plug according to claim 1, wherein the cap includes an annular shoulder on an outer perimeter for fixing to the housing.

### Claim 8 (depends on 1)

The prechamber spark plug according to claim 1, wherein the cap is formed without a through-hole and all through-holes are provided in the housing.

### Claim 9 (depends on 1)

The prechamber spark plug according to claim 1, wherein the cap includes exactly one central through-hole, and wherein the centerline of on the central through-hole lies in a center axis of the prechamber spark plug.

### Claim 10 (depends on 1)

The prechamber spark plug according to claim 1, wherein the ground electrode is fixed to the cap such that a centerline of the ground electrode lies in a center axis of the prechamber spark plug.

### Claim 11 (depends on 1)

The prechamber spark plug according to claim 1, wherein the cap is formed flat on an outer side, and the cap has on an inner side a profile for influencing an internal flow in the prechamber, the profile being a conical profile.

### Claim 12

A method for manufacturing a prechamber spark plug, comprising the following steps:
providing a housing, wherein an external thread with a start of thread is produced on the housing in one clamping operation, and, in the same clamping operation, at least two through-holes for a connection of a prechamber to an outer side of the prechamber spark plug is formed in the housing,
wherein each of the through-holes is disposed at a different angle to a center axis of the prechamber spark plug relative to one another.

### Claim 13 (depends on 12)

The method according to claim 12, wherein: (i) a cap is fixed to the housing before the external thread and the at least two through-holes are produced in the housing, or (ii) the cap is fixed to the housing after the external thread and the at least two through-holes are produced.