Prechamber Spark Plug Housing Strain Gauge Integration

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Solution Overview

Problem

Existing pre-chamber spark plugs lack efficient means to monitor engine operation and ignition behavior, particularly in lean-burning combustion engines, which affects engine output and efficiency.

Innovation Solution

Incorporating strain measuring strips on the housing of the pre-chamber spark plug to record deformations caused by combustion chamber pressure and pre-chamber pressure, allowing for the determination of motor operating variables without additional pressure sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional pressure sensors are installed in the combustion chamber to monitor engine operation, then measurement precision of engine operating variables is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvemonitoring of engine operationVSAvoidstructure of prechamber spark plug

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the pressure sensing function with the existing housing structure by attaching strain gauges to the housing surface. This merges the monitoring function into the structural component, eliminating the need for separate pressure sensors in the combustion chamber while maintaining measurement capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses the housing as an intermediary element that transmits pressure information to the strain gauges. Instead of directly placing sensors in the combustion chamber, the housing acts as a mediator that converts pressure changes into measurable strain changes on its surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If strain gauges are attached to the housing surface to detect pressure changes, then device complexity is reduced, but measurement precision may be affected due to indirect measurement

Engineering Contradiction:

Improvestructure of prechamber spark plugVSAvoiddetermination of combustion chamber pressure

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces direct mechanical pressure sensing with electrical strain measurement. Instead of using mechanical pressure sensors that directly contact the combustion chamber pressure, the system uses strain gauges that measure mechanical strain on the housing, which is then correlated to pressure through calibration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from direct pressure to strain. By measuring strain changes on the housing surface and using calibration relationships between strain and pressure, the system achieves accurate pressure determination without direct pressure contact.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the pre-chamber spark plug is tightly secured in the cylinder head to prevent loosening, then reliability is improved, but the ability to detect pressure-induced deformations is reduced

Engineering Contradiction:

Improvesecuring of pre-chamber spark plugVSAvoiddetection of housing deformation

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by differentiating the housing into a secured portion (with the securing element engaging the cylinder head) and a measurement portion (where strain gauges are attached). The securing element maintains reliable fixation while the strain gauge attachment points are positioned to detect pressure-induced deformations without interfering with the securing function.

Inventive Principle:

Principle #3Local quality

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 solution enables continuous monitoring of motor operating variables, improving engine output and ignition behavior by correlating housing deformations with combustion and pre-chamber pressures, thus enhancing engine efficiency and reducing the risk of spark plug loosening.

Implementation Method 1

at least one strain gauge is provided which is suitable for communicating with an evaluation unit, in particular an external one, wherein the at least one strain gauge is arranged on and/or in a surface of the housing for detecting strain changes

Methodology Applied

Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

the pre-chamber spark plug, in particular the housing, deforms during engine operation. These deformations can be quantitatively related to certain engine operating variables, in particular the combustion chamber pressure and/or the pre-chamber pressure

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4542016A1Prechamber spark plug, device and method for determining at least one engine operating variable

Publication Date: 2025.04.23 DKT VERW

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AI summary

The invention relates to a pre-chamber spark plug (1) comprising a central electrode (2), an insulator (3) at least partially surrounding the central electrode (2), and a housing (4) at least partially surrounding the insulator (3) with a pre-chamber cap (9) forming a pre-chamber (8), characterized in that at least one strain gauge (18', 18") is provided which is suitable for communicating with an evaluation unit, in particular an external one, wherein the at least one strain gauge (18', 18") is arranged on and/or in a surface (17', 17") of the housing (4) for detecting changes in strain, wherein the changes in strain correlate with at least one engine operating parameter, in particular the combustion chamber pressure and/or the pre-chamber pressure of the pre-chamber spark plug (1).