Standard Artificial Leak Device for Sealability Evaluation

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Solution Overview

Problem

Existing methods for evaluating sealability, such as those using chamber-type conductance test apparatus, face challenges in determining reliable threshold values due to variations in leak hole configurations and pressure differences, leading to inconsistent sealability evaluations.

Innovation Solution

A method involving leak-testing a test object with a sealing defect to obtain leakage characteristics, measuring conductance with a similar artificial leak device, and determining an allowable limit conductance to set a reliable threshold value for sealability evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a path length of the leak hole is determined based on thickness of a wall or sealed portion, then the evaluation process is simplified, but the reliability of the allowable limit conductance decreases because the actual defect hole path length may differ

Engineering Contradiction:

Improveevaluation process simplicityVSAvoidallowable limit conductance reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the approach from using geometric parameters (wall thickness) to using functional parameters (leakage characteristics measured under specific pressure conditions). By measuring the relationship between internal-external pressure difference and leak flow rate, the patent determines conductance based on actual leakage behavior rather than assumed geometric dimensions, thereby improving reliability while maintaining evaluation simplicity.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a standard artificial leak device is designed with a fixed conductance value, then the threshold setting becomes straightforward, but the adaptability to various defect configurations (orifice vs. capillary) is reduced

Engineering Contradiction:

Improvethreshold setting easeVSAvoiddefect configuration adaptability

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The invention introduces dynamic characteristics to the evaluation process by measuring leakage under varying pressure conditions. Instead of using a fixed conductance value based on static geometry, the patent determines conductance through dynamic measurement of the relationship between pressure difference and leak flow rate. This allows the evaluation to adapt to different defect configurations (orifice-type with pressure-proportional leakage vs. capillary-type with pressure-square-root leakage) while maintaining straightforward threshold setting procedures.

Inventive Principle:

Principle #15Dynamics

3Reliability

If leak testing is performed with multiple pressure differences to obtain accurate leakage characteristics, then the reliability of sealability evaluation improves, but the testing time and complexity increase

Engineering Contradiction:

Improvesealability evaluation reliabilityVSAvoidtesting time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention applies preliminary action by pre-establishing the relationship between pressure difference and leak flow rate for different defect types. By measuring leakage characteristics at multiple pressure points in advance and determining the functional relationship (linear for orifice, square-root for capillary), the system can quickly identify defect types and set appropriate thresholds without requiring extensive testing during actual evaluation, thereby reducing testing time while maintaining high reliability.

Inventive Principle:

Principle #10Preliminary action

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

Enhances the reliability of the allowable limit conductance and standard artificial leak devices, resulting in improved sealability evaluations by accounting for various defect configurations and pressure differences.

Implementation Method 1

obtaining a leakage characteristic showing a relationship between an internal-external pressure difference and a leak flow rate

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

measuring a conductance with respect to the leak-detected substance in a test object with a similar artificial leak

Methodology Applied

Scientific EffectConductance: Conduction (electrical)

Data Source

PatentUS11408795B2Sealability evaluation method and the like and standard artificial leak device

Publication Date: 2022.08.09 FUKUDA CO LTD

AI summary

It is an object of the present invention to enhance reliability of an allowable limit conductance used for setting a threshold value for evaluating sealability of a test object, and further, enhance reliability of the sealability evaluation. By leak testing a test object 9A with a sealing defect 9g, a leakage characteristic that shows a relationship between an internal-external pressure difference and a leak flow rate is obtained. A conductance of a test object with a similar artificial leak 9B having a similar artificial leak device 29 disposed therein, conducting the leak-detected substance is measured. The similar artificial leak device 29 has a leakage characteristic similar to the obtained leakage characteristic. An allowable limit conductance is obtained based on results of the measurement. Sealability of a test object 9 is evaluated based on a threshold value set with a standard artificial leak device 9S having the allowable limit conductance.