Active Bolster Vent with Flash Sleeve for Pressure Relief
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Solution Overview
Problem
Existing active bolster designs face challenges in managing pressure relief during impact, where insufficient venting can lead to weld seam failure and excessive venting results in loss of required knee loads for occupant restraint, making it difficult to maintain optimal pressure for effective crash protection.
Innovation Solution
A self-regulating vent system is created using a flash sleeve at the inflator-receiving hole edge, which maintains an initial seal until impact, allowing pressure relief through a gap between the inflator and sleeve, utilizing a flexible seal with varying thickness to manage pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the inflator receptacle wall is made thin to allow venting, then pressure relief is improved, but structural integrity and shape retention deteriorate
Solution Approach 1:
The receptacle wall is segmented into two distinct thickness zones: a thicker portion (0.060-0.120 inches) for structural integrity and shape retention, and a thinner portion (0.010-0.040 inches) for pressure relief and flexibility. This segmentation allows the same component to simultaneously satisfy both contradictory requirements of strength and pressure venting capability.
Solution Approach 2:
The receptacle wall exhibits non-uniform thickness with different local properties: the thicker regions provide structural support and maintain receptacle shape, while the thinner regions provide flexibility and enable pressure venting. This local quality variation resolves the contradiction by assigning different functional characteristics to different parts of the same component.
2Loss of energy
If the vent opening is made larger to improve pressure relief, then energy dissipation is improved, but knee load generation deteriorates
Solution Approach 1:
The vent opening size is made dynamic rather than fixed. The thinner wall portion acts as a flexible diaphragm that deflects under pressure, dynamically adjusting the vent opening size based on the instantaneous pressure differential. At low pressures, the opening remains small to maintain knee loads; at high pressures, the opening enlarges to dissipate energy, thus resolving the contradiction between energy dissipation and force generation.
Solution Approach 2:
The physical state of the vent wall changes from rigid to flexible under different pressure conditions. The thinner wall portion transitions from maintaining its original shape at low pressure to deflecting and creating an opening at high pressure. This parameter change allows the system to adaptively control the vent opening size, balancing energy dissipation and knee load requirements.
3Ease of manufacture
If a fixed vent opening is provided, then manufacturing simplicity is improved, but adaptability to different impact conditions deteriorates
Solution Approach 1:
The venting system is self-regulating and requires no external control mechanisms. The flexible thinner wall portion automatically responds to pressure changes by deflecting and adjusting the vent opening size according to the impact conditions. This self-service mechanism provides adaptability to different impact scenarios while maintaining manufacturing simplicity, as no complex control systems or movable parts are needed.
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 solution ensures consistent pressure relief proportional to the impact force, maintaining the integrity of the weld seam while generating necessary knee loads for effective occupant restraint, thus enhancing the overall crash protection efficiency.
Implementation Method 1
a flexible seal with varying thickness to manage pressure effectively
Implementation Method 2
An inflator with a gas outlet end and an electrical connector end is received in the inflator aperture with the gas outlet end inside the inflatable bladder
Data Source
AI summary
An active bolster mounts at an interior trim surface of a passenger compartment in an automotive vehicle. A plastic-molded, expandable front wall deploys toward a passenger in the passenger compartment. A plastic-molded back wall is joined around a substantially sealed perimeter with the front wall to form an inflatable bladder. The back wall includes an inflator receptacle defined by a raised recess wall having an inflator aperture. An inflator with a gas outlet end and an electrical connector end is received in the inflator aperture with the gas outlet end inside the inflatable bladder. The recess wall has a predetermined thickness for substantially retaining shape during inflation of the bladder. The inflator receptacle includes a flexible seal disposed around an inner edge of the inflator aperture comprised of a flashing edge bearing against the inflator and having a thickness less than the predetermined thickness of the recess wall.