Prechamber Spark Plug Lateral Electrode Mount for Precise Gap Setting

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Solution Overview

Problem

Existing prechamber spark plugs for mobile internal combustion engines face challenges in maintaining accurate electrode spacing between the central and ground electrodes, especially under varying load conditions, and are costly to manufacture in large quantities.

Innovation Solution

A prechamber spark plug design with a central and ground electrode arranged in a prechamber, where the ground electrode is positioned in a lateral hole of the housing with a clearance fit, allowing for precise adjustment of the electrode spacing using pneumatic pressure, and fastened using a weld joint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If prechamber spark plugs are manufactured in small batches for stationary gas engines, then manufacturing precision of electrode spacing can be maintained, but manufacturing costs increase significantly

Engineering Contradiction:

Improveelectrode spacing precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The ground electrode is designed to be movable within the housing during the adjustment process, allowing the electrode spacing to be dynamically adjusted after assembly. This enables precise spacing to be achieved through a simple adjustment and fixation process rather than requiring high-precision manufacturing tolerances, making mass production economically viable.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the approach from manufacturing with fixed precise dimensions to manufacturing with adjustable parameters. The ground electrode can be positioned at different locations within the housing, and its final position is determined by an adjustment mechanism rather than being fixed during manufacturing, allowing precise electrode spacing to be achieved through adjustment rather than precision manufacturing.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If electrode spacing is fixed during manufacturing, then mass production becomes feasible, but accurate maintenance of electrode spacing under varying load conditions becomes difficult

Engineering Contradiction:

Improvemass production capabilityVSAvoidelectrode spacing maintenance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The ground electrode is designed with the capability to be adjusted to different positions within the housing. This dynamic feature allows the electrode spacing to be optimized for different operating conditions while still enabling mass production through a standardized adjustable design. The adjustment can be performed during assembly or maintenance without requiring complex manufacturing processes.

Inventive Principle:

Principle #15Dynamics

3Ease of manufacture

If the ground electrode is firmly fixed in the housing, then manufacturing simplicity is maintained, but accurate adjustment of electrode spacing becomes impossible

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidelectrode spacing adjustability

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The housing is segmented into a lateral hole that receives the ground electrode, with distinct functional zones: a gap area that allows movement and adjustment of the ground electrode, and a fastening area that secures it in the adjusted position. This segmentation enables both easy manufacturing (standardized housing with lateral hole) and precise adjustment (movable ground electrode that can be positioned and fixed).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ground electrode transitions from a fixed component to a dynamically adjustable one. It can move freely within the gap area during adjustment, then be secured in the fastening area at the desired position. This dynamic capability allows precise electrode spacing to be achieved without complicating the manufacturing process.

Inventive Principle:

Principle #15Dynamics

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

The design enables accurate and adjustable electrode spacing, reducing manufacturing costs and making the spark plug suitable for mass production, while ensuring reliable ignition across various load ranges.

Implementation Method 1

allowing for precise adjustment of the electrode spacing using pneumatic pressure

Methodology Applied

Scientific EffectPneumatic pressure: Pressure Increase

Implementation Method 2

fastened using a weld joint

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS12278465B2Prechamber spark plug having accurately adjustable electrode gap, and associated method

Publication Date: 2025.04.15 ROBERT BOSCH GMBH

AI summary

A prechamber spark plug. The prechamber spark plug includes a central electrode and a ground electrode which are arranged in a prechamber, and a housing having a lateral hole, the ground electrode being arranged in the lateral hole in such a way that there is a gap area and a fastening area between the ground electrode and the housing.