Pre-Chamber Spark Plug Thread Orientation for Cap Alignment

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing methods for producing prechamber spark plugs are inefficient due to the need for coordinated positioning of components relative to the combustion chamber and fuel injectors in internal combustion engines, which complicates reliable ignition and gas exchange.

Innovation Solution

A method that allows for quick and simple alignment of the cap with through openings relative to an external thread on the prechamber spark plug, enabling precise positioning and reliable mounting, which simplifies the production process and ensures optimal gas exchange and ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cap is positioned and welded onto a pre-existing external thread, then the pre-chamber spark plug can be fixed in a cylinder head, but the alignment and positioning work becomes complex and time-consuming

Engineering Contradiction:
Improvereliable ignition and gas exchangeVSAvoidalignment and positioning time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The external thread is produced on the pre-chamber spark plug body before the cap is mounted. This preliminary action allows the cap to be attached in any orientation without requiring subsequent alignment work, as the thread positioning is already predetermined by the machining process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of mounting the cap first and then creating the external thread (which would require complex alignment), the invention inverts the sequence by producing the external thread on the plug body first, then mounting the cap. This reversal eliminates the need for precise alignment during cap installation

Inventive Principle:
Principle #13The other way round (Inversion)

2Manufacturing precision

If precise alignment of the cap with the external thread is performed, then reliable mounting is achieved, but the manufacturing process becomes complex and slow

Engineering Contradiction:
Improvealignment precision between cap and threadVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The external thread is machined on the pre-chamber spark plug body before cap installation. This preliminary threading operation establishes the precise positioning reference, allowing the cap to be mounted without requiring complex alignment procedures during assembly

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The alignment requirement is extracted from the cap installation step and transferred to the thread production step. By determining the thread start and end positions relative to the cap's through-holes during threading, the alignment complexity is removed from the assembly process

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If the cap is mounted in any orientation without alignment, then the manufacturing process is simplified, but the relative position between the through-hole and external thread becomes undefined

Engineering Contradiction:
Improvesimplicity of cap mountingVSAvoidrelative position definition
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The external thread is produced with predetermined thread start and end positions that are defined relative to the cap's through-holes. This preliminary threading operation, performed after cap installation, establishes the precise angular relationship between the thread and through-holes without requiring alignment during cap mounting

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the parameter definition approach by determining the thread start and end positions based on the cap's through-hole positions rather than requiring the cap to be positioned based on pre-existing thread references. This parameter redefinition allows flexible cap mounting followed by precise thread positioning

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method allows for reliable and repeatable assembly of prechamber spark plugs, ensuring efficient gas exchange and earlier, targeted introduction of flare jets into the combustion chamber, leading to faster and more complete combustion.

Implementation Method 1

a cap of the pre-chamber spark plug is placed and welded onto a pre-existing external thread

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP4062502B1Method for producing a pre-chamber spark plug
Publication Date: 2023.11.15 ROBERT BOSCH GMBH
  • EP4062502B1 patent drawingFigure 1
  • EP4062502B1 patent drawingFigure 2~3
  • EP4062502B1 patent drawingFigure 4~7

AI summary

The present invention relates to a method for producing a pre-chamber spark plug (1) comprising an external thread (4) and a cap (3) that has at least one through-opening (30), the method comprising the steps of: providing the pre-chamber spark plug (1) without the cap (3) and with a cylindrical circumferential surface (40) for the external thread (4); mounting the cap (3), which has at least one through-opening (30), in any orientation on the pre-chamber spark plug (1); and producing the external thread (4) on the circumferential surface (40) such that a thread start (42) and/or thread end (41) of the external thread (4) is oriented in a predetermined position with respect to the through-opening (30).