Spark Plug Insulation Inspection via Discharge Imaging
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Solution Overview
Problem
Existing methods for inspecting spark plugs fail to reliably distinguish between flashover and penetration discharge, leading to incorrect identification of defective products and reduced yield due to inadequate insulation performance testing.
Innovation Solution
A method involving the inspection of spark plugs with a tubular insulator and metallic shell, where the insulation performance is evaluated by applying voltage and photographing the area including the center electrode, insulator, and annular space to determine dielectric breakdown, using image analysis to differentiate between flashover and penetration discharge based on discharge location and luminance patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage is applied to the center electrode to inspect insulation performance, then the insulation performance can be evaluated, but both flashover and penetration discharge cannot be distinguished based on voltage waveform alone
Solution Approach 1:
The patent introduces a camera as an intermediary device to capture discharge location information. The camera records whether discharge occurs on the insulator surface (flashover) or through the insulator (penetration discharge), providing visual evidence that distinguishes between the two discharge types. This intermediary measurement method resolves the ambiguity of voltage waveform analysis alone.
Solution Approach 2:
The patent adds a spatial dimension to the inspection by capturing discharge location information through imaging. Instead of relying solely on electrical parameters (voltage waveform), the system incorporates visual/spatial information about where the discharge occurs, enabling discrimination between flashover and penetration discharge based on their distinct spatial characteristics.
2Reliability
If discharge occurs during voltage application, then insulation performance can be inspected, but flashover is incorrectly identified as penetration discharge leading to false defect classification
Solution Approach 1:
The camera acts as an intermediary that provides objective visual evidence of discharge location. By recording whether discharge occurs on the insulator surface or through it, the system prevents misclassification of flashover as penetration discharge, thereby avoiding unnecessary rejection of合格 products and improving yield.
Solution Approach 2:
The system incorporates visual feedback from the camera to verify the actual discharge location. This feedback mechanism allows the inspection system to distinguish between flashover and penetration discharge, providing accurate classification and preventing false defect identification that would reduce productivity.
3Device complexity
If only voltage waveform analysis is used for inspection, then the inspection process is simple, but the inspection accuracy is insufficient to differentiate discharge types
Solution Approach 1:
The patent merges electrical measurement (voltage waveform analysis) with optical measurement (discharge location imaging) into a unified inspection system. This combination maintains the simplicity of voltage application while adding visual verification capability, achieving both ease of operation and high measurement precision.
Solution Approach 2:
The inspection system performs multiple functions: it applies voltage to induce discharge, captures voltage waveform data, and simultaneously records discharge location through imaging. This multi-functional approach enables comprehensive inspection without significantly increasing operational complexity, as all measurements are obtained during a single voltage application cycle.
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 approach allows for accurate discrimination between flashover and penetration discharge, improving the inspection accuracy and yield by correctly identifying the insulation performance of spark plugs.
Implementation Method 1
an insulator having an axial hole extending along the axis thereof... When high voltage is applied to the center electrode (spark discharge gap), spark discharge occurs at the spark discharge gap... When the insulator has insufficient insulation performance (dielectric strength), the dielectric breakdown of the insulator may occur
Implementation Method 2
photographing an area including at least the center electrode, the insulator, and the annular space from a front end side in the direction of the axis when the voltage is applied to the center electrode... determining whether the dielectric breakdown has occurred based on the photographed image
Data Source
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AI summary
A method for inspecting a spark plug that includes a tubular insulator having an axial hole, a center electrode inserted into the axial hole at a front end side thereof, a tubular metallic shell disposed around the insulator, an annular space defined by an outer circumferential surface of the insulator, and an inner circumferential surface of the metallic shell and opened frontward. The method includes steps of: inspecting insulation performance of the insulator based on whether dielectric breakdown is caused in the insulator when a voltage is applied to the center electrode; photographing an area including at least the center electrode, the insulator, and the annular space from a front end side in the direction of the axis when the voltage is applied to the center electrode; and determining whether the dielectric breakdown has occurred based on the photographed image.