Seatbelt Retractor Load Limiting With Post-Spring Webbing Payout
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Solution Overview
Problem
Conventional seatbelt retractors with load-limiting features, such as torsion bars, may not effectively manage chest compression during vehicle impacts, as they rely on mechanical components that can fail to provide adequate protection due to complex interactions and limited adjustability.
Innovation Solution
A seatbelt retractor design that eliminates the torsion bar, using a post and spring mechanism with an inertia clutch and gear system to control webbing payout, allowing for regulated force distribution and absorption, thereby reducing chest compression through controlled webbing extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a torsion bar is used for load-limiting features, then the seatbelt can provide some additional limited extension of the webbing when force exceeds a threshold, but the complex mechanical interactions and limited adjustability reduce reliability in managing chest compression during impacts
Solution Approach 1:
The patent removes the torsion bar from the retractor mechanism and replaces it with a separate adjustable load-limiting device. This extraction allows the load-limiting function to be independently adjusted and calibrated, improving reliability while maintaining adaptability. The torsion bar's integrated function is separated into a dedicated adjustable component.
Solution Approach 2:
The patent introduces an adjustable load-limiting device that can be dynamically configured to different force thresholds. This dynamic adjustability allows the system to adapt to different impact scenarios and occupancy conditions, improving both adaptability and reliability compared to fixed torsion bar designs.
2Adaptability or versatility
If a torsion bar is used in the retractor, then load-limiting features are provided, but the complex mechanical components fail to provide adequate protection due to limited adjustability
Solution Approach 1:
The patent implements a dynamically adjustable load-limiting device that can be set to different force thresholds depending on the required protection level. This adjustability ensures reliable protection across various impact scenarios, overcoming the fixed limitations of torsion bar designs.
Solution Approach 2:
The patent changes the force threshold parameter through adjustable mechanical settings in the load-limiting device. This allows optimization of the webbing extension force to match specific safety requirements, improving reliability while maintaining adaptability to different protection needs.
3Ease of manufacture
If conventional mechanical components like torsion bars are used, then the seatbelt structure is established, but the complex interactions reduce ease of manufacture and increase device complexity
Solution Approach 1:
The patent segments the retractor system into distinct functional modules: the spool mechanism, the locking device, and the adjustable load-limiting device. This segmentation simplifies manufacturing by allowing each module to be produced and tested independently, then assembled together, reducing overall device complexity.
Solution Approach 2:
By extracting the load-limiting function from the integrated torsion bar design and placing it in a separate adjustable device, the patent simplifies the manufacturing process. Each component can be optimized and manufactured separately using standard processes, then assembled with straightforward connections.
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 design enhances occupant safety by providing controlled webbing extension and force absorption, reducing chest compression during impacts without the need for complex torsion bars, ensuring consistent and effective protection across various impact scenarios.
Implementation Method 1
a spring between the post and the frame... When force on the webbing exceeds the spring force of the spring, the post rotates relative to the frame toward the spring to compress the spring and provide regulated payout of the webbing
Implementation Method 2
a locking device operatively coupled between the spool and the post to engage the spool with the post
Data Source
AI summary
A seatbelt retractor includes a frame and a spool having a first end and a second end each rotatably supported by the frame. The spool is elongated on an axis from the first end to the second end. The seatbelt retractor includes a plurality of torsion posts fixed to the frame. The seatbelt retractor includes a locking device operatively coupled between the spool and the plurality of torsion posts.