Prechamber Spark Plug Housing Layout for Accurate Torch Jet Alignment

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Solution Overview

Problem

Prechamber spark plugs face alignment uncertainties during installation, leading to degraded ignition behavior in internal combustion engines due to the need for precise alignment of through-holes in the cap relative to the external thread, which complicates manufacturing and can result in thermal issues.

Innovation Solution

The prechamber spark plug design features through-holes in the housing instead of the cap, allowing for precise alignment and improved cooling, with a flat cap and a threaded region that can be produced in a single clamping operation, eliminating alignment problems and enhancing thermal management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If through-holes are provided in the cap, then gas exchange between prechamber and combustion chamber is enabled, but alignment uncertainty between cap and external thread occurs

Engineering Contradiction:

Improvemanufacturing processVSAvoidalignment precision of through-holes

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the cap and housing into a single integrated component. The through-holes are now formed directly in the housing structure, eliminating the separate cap assembly step and the associated alignment uncertainties between the cap and external thread. This integration ensures precise positioning of through-holes relative to the combustion chamber geometry.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If through-holes are provided in the cap, then gas exchange is enabled, but alignment problems between cap and start of thread occur

Engineering Contradiction:

Improveinstallation processVSAvoidalignment of through-holes to combustion chamber

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

By integrating the through-holes directly into the housing structure, the patent eliminates the separate cap alignment step during installation. The through-holes are precisely positioned during housing manufacturing, ensuring correct orientation to the combustion chamber without requiring field alignment operations.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If through-holes are provided in the cap, then gas exchange is enabled, but thermal cooling of through-hole regions is degraded

Engineering Contradiction:

Improvestructural simplicityVSAvoidthermal stress in through-hole regions

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The integration of through-holes into the housing structure allows the housing material itself to provide thermal management. The housing can be designed with adequate wall thickness and thermal conductivity to effectively cool the through-hole regions, eliminating the thermal isolation problem that would exist if through-holes were in a separate cap component.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12191638B2Prechamber spark plug having improved ignition properties

Publication Date: 2025.01.07 ROBERT BOSCH GMBH

AI summary

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.