Knee Airbag Module Fastening and Gas Generator Installation
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Solution Overview
Problem
Knee airbag modules in vehicles face challenges with long fastening surfaces required for mounting, which is problematic due to limited space, and the complex installation process of the gas generator, often necessitating a tipping motion that is time-consuming and requires high dexterity.
Innovation Solution
The fastening surfaces of the fastening flanges are arranged close to the gas generator axis, reducing lever forces and allowing for shorter fastening surfaces, and the installation orientation of the gas generator is made oblique to facilitate a simple linear installation motion, eliminating the need for tipping during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fastening surfaces of the fastening flanges are spaced apart from the gas generator axis, then the gas generator can be securely fastened to the housing, but the lever forces generated during airbag deployment require correspondingly long fastening surfaces in the vehicle, which is problematic due to limited mounting space
Solution Approach 1:
The patent repositions the fastening surfaces from a lateral arrangement (perpendicular to gas generator axis) to a longitudinal arrangement (parallel to gas generator axis), effectively changing the dimensional orientation of the fastening mechanism. This allows the fastening surfaces to be positioned close to the gas generator axis while still providing adequate fastening security, as the longitudinal positioning eliminates the lever arm that previously required long fastening surfaces.
Solution Approach 2:
The patent changes the positional parameter of the fastening surfaces relative to the gas generator axis, moving them from a spaced-apart configuration to a close-proximity configuration. This parameter change reduces the lever forces acting on the fastening surfaces, thereby allowing shorter fastening surfaces to provide the same fastening security.
2Ease of operation
If the gas generator is installed with a tipping motion to accommodate the opening in the peripheral side wall, then the end of the gas generator becomes accessible from outside the housing, but the installation process becomes time-consuming and requires high dexterity
Solution Approach 1:
The patent changes the installation trajectory from a complex tipping motion (rotational degree of freedom) to a simple linear insertion motion (translational degree of freedom). By orienting the opening in the peripheral side wall to align with the longitudinal axis of the gas generator, the installer can simply push the gas generator straight into the housing without requiring awkward manual manipulation or specialized tooling.
Solution Approach 2:
The housing design with the obliquely oriented opening automatically guides the gas generator into the correct position during linear insertion. The geometry of the opening and the housing structure work together to self-align and self-position the gas generator, eliminating the need for complex manual tipping motions or external alignment tools.
Data Source
AI summary
The invention relates to a knee airbag module having a housing, an airbag accommodated in the housing and a substantially cylindrical gas generator (50) accommodated in the housing for filling the airbag, wherein the housing has an upper wall (12) and a peripheral side wall having a front section, a rear section (24) and two side sections. In this connection, at least one side section has, adjacent to the front (22) section, an opening (30) through which one end (54) of the gas generator (50) passes at least in part through the side wall. From each of the two side sections a respective fastening flange (40) extends with a respective fastening section (40a) having a fastening surface. In order for the fastening surfaces to be relatively short, the fastening surfaces overlap the radial extension of the gas generator (50) in a vertical projection direction at least, wherein at least the fastening section (40a) of the fastening flange (40) which is adjacent to the opening (30) is spaced apart from the end (54) of the gas generator (50) facing same. Furthermore, in order to achieve simple mounting of the gas generator, the region of the side wall section in which the opening (30) is disposed can extend obliquely with respect to the gas generator axis.