Single Micro-Gas Generator Dual Spool Seat Belt Pretensioner
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Solution Overview
Problem
Existing dual spool seat belt retractor systems with pretensioning functions are costly and complex due to the need for separate pretensioning mechanisms for each spool, which complicates the control system and increases component count, making it difficult to meet stringent automotive safety requirements.
Innovation Solution
A dual spool retractor device using a single micro-gas generator (MGG) to provide pretensioning for both spools, where the MGG acts on a piston that pushes a metal band or wire wrapped on pulleys of both spools, reducing the need for duplicate pretensioner mechanisms and simplifying the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pretensioning mechanisms are provided for each retractor spool, then pretensioning performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two separate pretensioning mechanisms into a single integrated mechanism. A single micro-gas generator activates both pretensioning pistons simultaneously through a common drive arrangement, reducing the number of components while maintaining pretensioning performance for both lap and shoulder belt spools
Solution Approach 2:
The single pretensioning mechanism is designed to perform multiple functions by acting on both lap and shoulder belt spools. The drive arrangement can distribute the pretensioning force to either or both spools as needed, providing universal pretensioning capability across different belt configurations
2Reliability
If two separate micro-gas generators are used for dual spool pretensioning, then pretensioning reliability is improved, but cost and device complexity increase
Solution Approach 1:
The patent merges two separate micro-gas generators into a single unit that can simultaneously activate both pretensioning pistons. This single MGG provides reliable pretensioning for both spools while reducing component count, assembly complexity, and manufacturing cost
3Reliability
If independent pretensioning systems are provided for each spool, then pretensioning effectiveness is improved, but packaging space requirements increase
Solution Approach 1:
The patent merges the pretensioning systems into a compact integrated unit where the single micro-gas generator and drive arrangement occupy significantly less space than two separate systems would require, while maintaining full pretensioning effectiveness for both spools
Solution Approach 2:
The drive arrangement is designed with a nested structure where components are arranged concentrically or in overlapping configurations, allowing the pretensioning mechanism to fit into a compact volume that accommodates both spools without requiring separate dedicated spaces
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 reduces costs and complexity while maintaining performance by allowing simultaneous pretensioning of both lap and shoulder belt sections with a single MGG, decoupling the pretensioning motion to prevent interference from resistance in one spool affecting the other, and optimizing packaging space.
Implementation Method 1
a single micro-gas generator (MGG) which produces a pretensioning effect for both spools
Implementation Method 2
the MGG acts on a piston which, when displaced, pushes a metal band or wire which is in turn wrapped on pulleys of both spools
Data Source
AI summary
A dual spool retractor device for seat belts in a motor vehicle including a frame, two spools rotatably mounted to the frame, and a pretensioning system providing pretensioning rotation for both the spools. The spools are pretensioning through the activation of a micro-gas generator. The gas generator can provide gas to a single or a pair of gas cylinders. One or more flexible numbers such as a metal band or cable is used which is coupled to one or both spools via a pulley. Activation of the gas generator forces a piston to move in a manner which exerts tension on the flexible member(s) thereby unwinding the flexible member from the spool pulley and providing pretensioning rotation of the respective belt spool.