Spark Plug Insulator Dielectric Breakdown Detection
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Solution Overview
Problem
Conventional methods for inspecting spark plug insulators for dielectric breakdown often misidentify air discharge as dielectric breakdown, leading to incorrect elimination of spark plugs during manufacturing, which decreases productivity.
Innovation Solution
A method using an acoustic emission inspection device that applies a predetermined voltage and analyzes the oscillating wave signals with Fast Fourier Transform (FFT) to distinguish between dielectric breakdown and air discharge by setting specific integral thresholds for accurate identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a predetermined voltage is applied between the center electrode and the ground electrode to inspect dielectric breakdown, then the inspection method is simple, but it cannot accurately distinguish between air discharge and dielectric breakdown
Solution Approach 1:
The patent introduces acoustic emission signals as an intermediary to detect dielectric breakdown. By placing acoustic emission sensors near the insulator and analyzing the signals generated during voltage application, the system can distinguish between air discharge and true dielectric breakdown based on the characteristics of the acoustic emissions, thereby resolving the inability to accurately identify dielectric breakdown while maintaining inspection simplicity
Solution Approach 2:
The patent replaces the conventional electrical measurement method with an acoustic emission detection method. Instead of relying solely on electrical signals that cannot distinguish between air discharge and dielectric breakdown, the system uses acoustic sensors to detect the mechanical vibrations and sound waves generated during dielectric breakdown, providing accurate identification while keeping the inspection process simple
2Difficulty of detecting and measuring
If the AE method is used to determine dielectric breakdown, then detection capability is enhanced, but it cannot distinguish between discharge due to dielectric breakdown and air discharge
Solution Approach 1:
The patent segments the acoustic emission signal analysis into multiple frequency components using Fast Fourier Transform (FFT). By dividing the signal spectrum into different frequency bands and analyzing the distribution of acoustic energy across these bands, the system can distinguish between air discharge and dielectric breakdown, as they produce characteristic differences in frequency content and energy distribution
Solution Approach 2:
The patent focuses on analyzing only the specific frequency components and energy distribution characteristics that are most indicative of dielectric breakdown, rather than examining the entire acoustic signal. By concentrating on the relevant partial features (frequency spectrum distribution and energy concentration patterns), the system achieves accurate discrimination between discharge types while maintaining efficient detection
3Reliability
If spark plugs with normal discharge are eliminated from manufacturing, then quality control is maintained, but productivity decreases
Solution Approach 1:
The patent implements a feedback mechanism where acoustic emission signals are continuously monitored and analyzed during the inspection process. The system provides real-time feedback on the discharge type detected, allowing for accurate identification of spark plugs with normal discharge versus those with dielectric breakdown. This feedback enables selective elimination only of defective units, maintaining quality while preserving productivity by avoiding the elimination of normal spark plugs
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 precise differentiation between through discharge and air discharge, reducing incorrect eliminations and enhancing spark plug manufacturing efficiency by ensuring only defective plugs with dielectric breakdown are removed.
Implementation Method 1
an inspection method for determining whether there is damage in a structural body using an acoustic emission method (which may be hereafter referred to as an 'AE method') is also known
Data Source
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AI summary
[Object] To provide a technology such that a decision about dielectric breakdown of an insulator can be made accurately. [Solution] A method for manufacturing a spark plug includes: a preparation step of preparing a specimen provided with a center electrode, an insulator, a metal shell, and a ground electrode; and an inspection step of applying a predetermined voltage between the ground electrode and the center electrode of the prepared specimen, and determining whether dielectric breakdown is caused in the insulator. The inspection step includes a calculation step of receiving an oscillating wave generated from the specimen upon application of the predetermined voltage to the specimen, obtaining a power spectrum by subjecting an oscillating wave signal representing the oscillating wave to fast Fourier transform, and then calculating an integral of a predetermined frequency range in the power spectrum, and a judgment step of judging whether discharge is caused by dielectric breakdown of the insulator by utilizing the integral.