# US 12,184,042 B2 · Economical pre-chamber spark plug

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- Number: US 12,184,042 B2
- Document ID: US12184042B2
- Status: Granted
- Kind: B2
- Application number: 18/044,036
- Filed: 2021-07-13
- Published: 2023-10-05
- Granted: 2024-12-31
- Earliest claimed: 2020-09-10
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Stephan Kaske; Alexander Schramm; Andreas Benz; Matthias Blankmeister; Anatolij Odegov
- Web page: https://patentgrep.com/patent/US12184042B2

## CPC

- H01T 13/39: Selection of materials for electrodes
- H01T 13/20: characterised by features of the electrodes or insulation
- H01T 13/32: characterised by features of the earthed electrode
- H01T 13/54: having electrodes arranged in a partly-enclosed ignition chamber
- 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 pre-chamber spark plug includes (i) a middle electrode with a first noble metal body which has a first end spark face, (ii) a ground electrode with a second noble metal body which has a second end spark face, (iii) a housing, with the ground electrode being fixed in the housing, (iv) an insulator which electrically insulates the middle electrode with respect to the ground electrode, and (v) a cap, which together with a part of the housing, defines a pre-chamber. The first end spark face and the second end spark face are arranged oppositely at a distance from one another.

## Claims

### Claim 1

A pre-chamber spark plug, comprising:
a housing extending along a longitudinal axis;
a middle electrode with a first noble metal body, which has a first end spark face, the middle electrode extending along the longitudinal axis within the housing;
a ground electrode with a second noble metal body, which has a second end spark face, the ground electrode fixed within a through hole extending through the housing laterally with respect to the longitudinal axis;
an insulator within the housing which electrically insulates the middle electrode with respect to the ground electrode; and
a cap, which together with a part of the housing, defines a pre-chamber,
wherein the first end spark face and the second end spark face are arranged oppositely at a distance from one another,
wherein the first noble metal body is arranged on a retaining element which is connected to the middle electrode, and
wherein the retaining element is configured as a ring comprising a middle opening in which the middle electrode is arranged.

### Claim 2 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein:
the first noble metal body is arranged laterally on the middle electrode, and
the first end spark face is parallel to the longitudinal axis of the pre-chamber spark plug.

### Claim 3 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein the second noble metal body is arranged on a lateral flat section of the ground electrode and the first noble metal body is arranged on an end side of the middle electrode.

### Claim 4 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein:
the middle electrode comprises on its end side a slope on which the first noble metal body is arranged,
the slope is arranged at a first angle to the center axis of the pre-chamber spark plug,
the ground electrode is arranged at a second angle to the center axis, and
the second noble metal body is arranged on an end side of the ground electrode.

### Claim 5 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein the retaining element comprises on the outer circumference a lateral flat section to which the first noble metal body is attached.

### Claim 6 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein at least one of the middle electrode and the retaining element comprises a shoulder aligned with the other of the at least one of the retaining element and the middle electrode.

### Claim 7 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein the first noble metal body and the second noble metal body have shapes which are identical.

### Claim 8 (depends on 1)

The pre-chamber spark plug according claim 1, wherein the first noble metal body and/or the second noble metal body is a cylindrical pin.

### Claim 9 (depends on 1)

The pre-chamber spark plug according to claim 1, wherein the first end spark face and the second end spark face are arranged at an acute angle in relation to the center axis of the pre-chamber spark plug.

### Claim 10 (depends on 2)

The pre-chamber spark plug according to claim 2, wherein the first noble metal body is arranged in a lateral blind hole in the middle electrode.

### Claim 11 (depends on 4)

The pre-chamber spark plug according to claim 4, wherein the first angle is in a range from 30° to 60°.

### Claim 12 (depends on 9)

The pre-chamber spark plug according to claim 9, wherein:
a first slope is formed on the first noble metal body and a second slope is formed on the second noble metal body, or
the first noble metal body and the second noble metal body are each cylindrical, and a first slope is formed on the middle electrode and a second slope on the ground electrode.