Spark Plug Ground Electrode Orientation for Engine Cooling

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Solution Overview

Problem

Pre-ignition in internal combustion engines occurs frequently due to uncontrolled ignition before the planned ignition point, leading to high cylinder pressures and potential engine failure, as the spark plug's high temperature contributes to heat transfer to the air-fuel mixture.

Innovation Solution

The spark plug is oriented in a specific alignment with respect to the intake ports to maximize cooling by the air flow generated during engine operation, with the open end of the ground electrode directed between the intake ports, reducing the temperature of the spark plug and minimizing pre-ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the spark plug is mounted in a conventional orientation, then the ignition function is maintained, but the ground electrode temperature becomes too high causing pre-ignition

Engineering Contradiction:
Improveground electrode temperatureVSAvoidpre-ignition frequency
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies parameter changes by modifying the orientation angle of the spark plug ground electrode relative to the intake port. Specifically, the ground electrode is oriented at an angle of 10° to 30° with respect to the direction perpendicular to the intake port axis, which optimizes the cooling effect of the incoming air flow on the ground electrode, thereby reducing its temperature and preventing pre-ignition.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the spark plug orientation is optimized for cooling, then pre-ignition is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvepre-ignition resistanceVSAvoidspark plug alignment tolerance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent defines a specific angular range (10° to 30°) for the ground electrode orientation, which provides a sufficient tolerance window for manufacturing and assembly variations. This range is wide enough to accommodate normal manufacturing tolerances while still achieving the cooling effect, thus balancing reliability improvement with manufacturing feasibility.

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 alignment significantly reduces the frequency of pre-ignition and thermal overload, extending the service life of the spark plug by maintaining lower temperatures throughout the engine's operating map.

Implementation Method 1

the air flow generated by the intake ports during operation of the internal combustion engine is used to cool the ground electrode of the spark plug

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2715098B1Arrangement of a spark plug in a cylinder of an internal combustion engine of a vehicle
Publication Date: 2023.07.12 VOLKSWAGEN AG
  • EP2715098B1 patent drawingFigure 1~2
  • EP2715098B1 patent drawingFigure 3~4

AI summary

A cylinder (7) of an internal combustion engine (8) for a vehicle (10) comprises at least one inlet duct (4) and a spark plug (1) which for its part comprises an earth electrode (2). The spark plug (1) is fastened in the cylinder (7) in such a way that, during operation of the internal combustion engine (8), the earth electrode (2) is cooled in as optimum a manner as possible by an air flow which is generated by the at least one inlet duct (4).