Angled Gas Ejection Holes in Airbag Pyrotechnical Generators
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Solution Overview
Problem
Current pyrotechnical gas generators for airbags face challenges in reducing weight and size while maintaining effective gas flow and minimizing jet aggressiveness, as existing low-burning temperature compositions are insufficient to eliminate the need for a separate filtering device.
Innovation Solution
A pyrotechnical gas generator design featuring a cylindrical casing with gas ejection holes that extend at a non-zero angle with the tangential plane, multiple nozzles arranged on annular rings, and notches for simplified production, which integrates filtering and gas ejection functions, reducing weight and jet aggressiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If low burning temperature compositions are used to reduce weight and size, then weight and size decrease, but jet aggressiveness remains too high to eliminate the filtering device
Solution Approach 1:
The patent changes the geometric parameters of the gas ejection holes, specifically orienting them at an angle between 45° and 90° relative to the radial direction. This angular orientation modifies the gas jet trajectory and distribution, reducing aggressiveness toward the bag while maintaining effective inflation. This parameter change allows the system to achieve both weight reduction and sufficient jet control without requiring additional filtering devices.
Solution Approach 2:
The patent applies different functional qualities to different regions by orienting gas ejection holes at specific angles in different zones of the generator. The angular orientation creates localized variations in gas flow direction and intensity, directing jets away from sensitive areas (the bag) while maintaining effective inflation pressure. This local quality differentiation resolves the contradiction between weight reduction and jet aggressiveness control.
2Strength
If traditional round holes are used in steel casing, then structural strength is maintained, but weight and complexity increase
Solution Approach 1:
The patent segments the gas ejection function into multiple angled holes distributed around the casing periphery rather than using a single large opening or traditional radial holes. This segmentation allows the casing to maintain structural integrity while using thinner, lighter material. The distributed angular holes provide sufficient gas ejection capability without requiring heavy reinforcement, thus reducing overall weight while maintaining strength.
3Object-affected harmful factors
If filtering device is included to control particle emission, then bag protection is improved, but weight and device complexity increase
Solution Approach 1:
The patent integrates multiple functions into the gas ejection holes themselves. The angled holes serve simultaneously as: (1) gas ejection pathways, (2) flow direction control mechanisms, and (3) particle filtration structures. The angular geometry and positioning create natural flow patterns that separate and trap particles before they reach the bag, eliminating the need for separate filtering components. This multi-functionality reduces both weight and complexity while maintaining protection capability.
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 design achieves a reduced weight, maximized gas flow, and minimized jet aggressiveness, eliminating the need for a separate filtering device by distributing energy evenly and filtering large particles, thus enhancing safety and efficiency.
Implementation Method 1
at least one pyrotechnical charge
Implementation Method 2
each gas ejection hole extends in a output plane forming a non-zero angle with a tangential plane which is tangent to said annular wall at said gas ejection hole
Data Source
AI summary
A pyrotechnical gas generator includes at least one pyrotechnical charge, at least one ignitor, and a cylindrical casing enclosing the at least one charge and the at least one ignitor, the cylindrical casing having an axial direction and a radial direction and including an annular wall extending along the axial direction of the casing, and gas ejection holes arranged on the annular wall. Each gas ejection hole extends in a output plane forming a non-zero angle with a tangential plane which is tangent to the annular wall at the gas ejection hole.