Spring-Loaded Seatbelt Guide Assembly for Chest Load Limiting
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Solution Overview
Problem
Conventional seatbelts do not effectively limit chest compression during vehicle impacts, as they lack a mechanism to manage excessive force exerted on occupants, potentially leading to injury.
Innovation Solution
A load-limiting assembly that includes a seatbelt retractor, a spring-loaded seatbelt guide, and a slot system, where the spring biases the seatbelt guide against the terminal end of the slot, allowing limited extension of the webbing when force exceeds a threshold, reducing the load on the occupant's chest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seatbelt retractor locks webbing during vehicle impact, then the webbing prevents occupant forward movement, but the full force of the impact is applied to the occupant's chest causing potential injury
Solution Approach 1:
A spring mechanism is pre-installed in the load-limiting assembly to provide cushioning force before impact occurs. During normal operation, the spring is compressed and stores energy. When impact force exceeds the spring's resistance, the spring allows controlled webbing payout, absorbing impact energy and limiting the force transmitted to the occupant's chest.
Solution Approach 2:
The system changes the mechanical parameter of webbing tension dynamically. The spring mechanism allows the webbing tension to transition from a locked high-tension state to a controlled lower-tension state during impact, based on the applied load threshold. This parameter change limits chest compression while maintaining restraint effectiveness.
2Stability of the object's composition
If the seatbelt webbing is completely locked during impact, then occupant forward movement is restricted, but chest compression and potential injury occur due to excessive force
Solution Approach 1:
The spring is pre-compressed to provide immediate cushioning when impact force is applied. This beforehand preparation allows the system to transition smoothly from locked to load-limiting mode without sudden force spikes to the occupant.
Solution Approach 2:
The spring mechanism enables dynamic parameter change in webbing tension based on impact severity. Below the load threshold, the spring maintains high tension for stability. Above the threshold, it allows tension reduction to limit chest compression force.
3Object-affected harmful factors
If a load-limiting mechanism with spring and seatbelt guide is added, then chest compression is limited during impact, but the device complexity increases
Solution Approach 1:
The load-limiting assembly is merged with the existing seatbelt retractor system. The spring, seatbelt guide, and slot mechanism are integrated into the retractor housing, sharing common mounting points and structural elements. This reduces overall system complexity compared to a separate load-limiting device.
Solution Approach 2:
The seatbelt guide acts as an intermediary component between the webbing and the spring mechanism. It translates webbing tension into linear spring compression through the slot constraint, providing a simple mechanical interface that reduces the complexity of direct spring-webbing interaction.
4Object-affected harmful factors
If the spring allows webbing extension when force exceeds threshold, then load on occupant is reduced, but the webbing extends further from the retractor
Solution Approach 1:
The spring provides beforehand cushioning that allows controlled webbing extension during impact. The extension length is predetermined by the spring's compression distance and the slot geometry, ensuring load reduction while limiting excessive payout.
Solution Approach 2:
The system changes the webbing extension parameter dynamically based on impact force. Below threshold, extension is minimal (locked mode). Above threshold, extension increases controllably as the spring compresses, providing load reduction while managing extension length through the mechanical constraints of the slot and spring travel distance.
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 load-limiting assembly effectively limits chest compression by allowing controlled release of webbing tension when excessive force is applied, thereby reducing the load on the occupant during sudden deceleration events.
Implementation Method 1
A spring is provided between the frame and the seatbelt guide. The spring biases the seatbelt guide against the terminal upper end of the slot.
Implementation Method 2
When the force exerted by the webbing exceeds a load-limiting threshold, the seatbelt guide moves downwardly, compressing the spring against the frame.
Data Source
AI summary
An assembly includes a vehicle pillar elongated along an axis. The assembly includes seatbelt retractor and a webbing retractably extendable from the retractor. The seatbelt retractor is lockable from an unlocked position in which the webbing is extendable from and retractable into the retractor to a locked position in which the retractor restricts extension of the webbing from the retractor. The assembly includes a frame supported by the pillar and defining a slot elongated along the axis of the pillar. The slot has a terminal upper end. The assembly includes a seatbelt guide slideably engaged with the slot. The seatbelt retractor is below the seatbelt guide. The webbing extends upwardly from the seatbelt retractor around the seatbelt guide. The assembly includes a spring between the frame and the seatbelt guide. The spring biases the seatbelt guide against the terminal upper end of the slot.