Spark Plug Electrode Gap Adjustment Device with Force Limiter

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Solution Overview

Problem

The existing methods for adjusting the electrode gap in spark plugs are manual, time-consuming, prone to errors, and can damage the spark plugs, leading to reduced service life and increased downtime in industrial gas engines.

Innovation Solution

A device comprising an abutment, a spacer plate, and a stamp with a force limiter, where the spacer plate is positioned between the electrodes and the stamp applies a controlled forming force to adjust the gap precisely, minimizing the risk of damage and ensuring reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual adjustment methods (pliers or impact tool) are used to adjust the electrode gap, then the adjustment can be performed, but the process is time-consuming and prone to errors leading to damaged spark plugs

Engineering Contradiction:
Improveease of electrode gap adjustmentVSAvoidadjustment time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent introduces a specialized adjustment device as an intermediary tool between the operator and the spark plug electrodes. This device includes a holder that securely clamps the spark plug, a movable electrode arm with precise positioning mechanisms, and a controlled actuation system. The intermediary device eliminates the need for direct manual manipulation with inappropriate tools like pliers, providing controlled and precise electrode gap adjustment while preventing damage to the spark plug components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If manual adjustment with impact tools is used, then the electrode gap can be adjusted, but excessive force can damage weld seams or ceramic insulation

Engineering Contradiction:
Improveease of electrode gap adjustmentVSAvoidspark plug integrity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The adjustment device incorporates built-in force limitation and control mechanisms that prevent excessive force from being applied to the spark plug. The device includes a controlled actuation system that applies gradual, measured force to adjust the electrode gap, and a reset mechanism that prevents over-compression. This beforehand cushioning approach ensures that weld seams and ceramic insulation are protected from damage while still enabling effective electrode gap adjustment.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If manual adjustment is performed by operating personnel, then the electrode gap can be adjusted, but the process is tedious and requires skilled personnel

Engineering Contradiction:
Improveease of electrode gap adjustmentVSAvoidadjustment speed
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The adjustment device is designed to be self-guiding and self-regulating, with built-in mechanical stops, aligned features, and automatic positioning mechanisms that guide the operator through the adjustment process. The device includes a standardized interface that automatically positions the spark plug correctly, and a controlled actuation mechanism that automatically applies the appropriate force and displacement. This self-service design reduces the skill level required and enables faster adjustment by eliminating manual calculation and estimation steps.

Inventive Principle:
Principle #25Self-service

4Productivity

If inaccurate electrode distance adjustment is performed, then the adjustment can be completed quickly, but the service life of the spark plug is reduced

Engineering Contradiction:
Improveadjustment speedVSAvoidelectrode gap accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The adjustment device incorporates pre-set positioning mechanisms, standardized spacer elements, and pre-calibrated measurement scales that provide accurate electrode gap settings before the actual adjustment is made. The device includes reference features and mechanical stops that ensure the electrode gap is set to the correct specification before final tightening. This preliminary action approach ensures accuracy is built into the process from the beginning, eliminating the need for time-consuming trial-and-error adjustments.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3602707B1Device for setting the electrode gap on a spark plug
Publication Date: 2022.05.11 ROBERT BOSCH GMBH
  • EP3602707B1 patent drawingFigure 1
  • EP3602707B1 patent drawingFigure 2
  • EP3602707B1 patent drawingFigure 3

AI summary

The invention relates to a device (2) for setting a spacing (A) between a first electrode (4) and a second electrode (5) of a spark plug (1), comprising at least one counter bearing (23), a spacer plate (26) and a die (24), which are arranged along a longitudinal axis (X-X), wherein the counter bearing (23) is designed to support the spark plug (1), wherein the spacer plate (26) is arranged between the counter bearing (23) and the die (24) in the direction of the longitudinal axis (X-X), wherein the spacer plate (26) is designed to be arranged between the first electrode (4) and the second electrode (5), and wherein the die (24) is designed to apply a forming force to the second electrode (5) in the direction of the longitudinal axis (X-X).