Airbag Inflator Filter Orientation for Higher Slag Capture
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Solution Overview
Problem
Existing airbag inflator filters made from expanded metal face challenges in capturing slag effectively while maintaining low backpressure and preventing degradation of solid propellant due to the rough side's cheese grater effect, necessitating the smooth side to face inward, which limits slag capture efficiency.
Innovation Solution
Flatten the expanded metal sheet to reduce its thickness by 25-45% to minimize the cheese grater effect, then orient the flattened rough side inward to enhance slag capture without compromising propellant degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the smooth side of expanded metal faces inward, then propellant degradation is prevented, but slag capture efficiency is reduced
Solution Approach 1:
The patent inverts the conventional orientation by placing the rough side of the expanded metal facing inward toward the propellant, rather than the smooth side. This inversion allows the rough surface to capture slag effectively while the smooth side faces outward to prevent propellant degradation during storage and handling.
Solution Approach 2:
The patent applies different surface qualities to different locations: the rough side is positioned inward to maximize slag capture, while the smooth side is positioned outward to minimize propellant degradation. This spatial differentiation of surface properties resolves the contradiction between slag capture and propellant protection.
2Object-generated harmful factors
If the rough side of expanded metal faces inward, then slag capture is enhanced, but propellant degradation occurs due to cheese grater effect
Solution Approach 1:
The patent inverts the conventional orientation by placing the rough side of the expanded metal facing inward toward the propellant, rather than the smooth side. This inversion allows the rough surface to capture slag effectively while the smooth side faces outward to prevent propellant degradation during storage and handling.
3Weight of moving object
If expanded metal thickness is reduced, then filter weight and cost decrease, but structural strength and filtering capacity are compromised
Solution Approach 1:
The patent utilizes the dual-surface characteristics of expanded metal as a composite structure, where the rough and smooth sides provide different functional properties. This allows the filter to achieve effective slag capture and propellant protection without requiring increased thickness, thereby reducing overall filter weight and cost.
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
The solution achieves improved slag capture, meeting USCAR standards with reduced slag emission, while maintaining propellant integrity and filter performance, thus enhancing airbag safety and efficiency.
Implementation Method 1
Filters for airbag inflators need to satisfy a number of demanding criteria. Such filters serve to capture the extensive debris (slag) that is generated during the rapid burning of an airbag's solid propellant.
Implementation Method 2
Flatten the expanded metal sheet to reduce its thickness by 25-45% to minimize the cheese grater effect
Data Source
AI summary
A flattened expanded metal strip (9) is wrapped into an airbag inflator filter (21) with the strip oriented such that the flattened rough side (17) of the strip is pointing toward the inside diameter (ID) of the filter and the flattened smooth side (15) is pointing towards the outside diameter (OD). With this orientation, the filter (21) is able to capture more slag than filters made using the standard wrapping method in which the smooth side is oriented inward. The expanded metal can be of various types including, for example, variable expanded metal (VEM) or standard expanded metal (SEM).