Seatbelt Deformation Portion Stabilizes Initial Load
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Solution Overview
Problem
Conventional seatbelt devices experience unstable load variation during the initial stage of operation due to rapid changes in webbing tension, which can compromise occupant safety and protection.
Innovation Solution
A seatbelt device with a deformation portion, such as rubber, elastomer resin, or foam metal, is introduced between the spindle and the second energy absorbing member, which absorbs impact by deforming when the spindle rotates, stabilizing the load and reducing frictional resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seatbelt device uses emergency locking mechanism and energy absorbing mechanism without deformation portion, then the webbing can unreel to absorb impact energy, but the webbing tension increases rapidly and causes unstable load variation during initial stage of operation
Solution Approach 1:
A deformation portion is introduced as an intermediary element between the spindle and the second energy absorbing member (bending element). This deformation portion absorbs impact energy through its own deformation, mediating the force transmission and preventing direct transmission of rapid tension changes to the webbing, thereby stabilizing the load during the initial stage of operation.
Solution Approach 2:
The deformation portion is positioned to engage beforehand with the bending element, providing preliminary cushioning against impact forces. When collision occurs, the deformation portion deforms first to absorb initial impact energy, cushioning the system against sudden load spikes before the bending element fully engages, thus preventing unstable load variation.
2Speed
If the spindle rotates rapidly during emergency operation, then the webbing can unreel quickly to accommodate occupant movement, but frictional resistance varies unstably causing load fluctuations
Solution Approach 1:
The deformation portion acts as a mediator between the rapidly rotating spindle and the bending element. It smooths out the frictional resistance variations caused by rapid rotation by deforming in a controlled manner, thereby maintaining stable load conditions even during high-speed webbing unreeling operations.
3Device complexity
If the second energy absorbing member is directly engaged with the spindle, then the structure is simplified, but impact energy causes unstable load variation and excessive webbing tension
Solution Approach 1:
The deformation portion is introduced as a compact intermediary element between the spindle and the bending element. While it adds a component, the deformation portion is relatively simple in structure (can be a rubber element, elastomer, or foam metal), and it provides crucial safety function by stabilizing load and preventing excessive webbing tension, thus improving reliability with minimal complexity increase.
Solution Approach 2:
The deformation portion can be made from composite materials such as rubber, elastomer resin, or foam metal, which combine energy absorption capability with structural integrity. These materials provide effective impact mitigation while maintaining a compact and relatively simple structure, balancing device complexity with occupant safety requirements.
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 deformation portion effectively suppresses unstable load variation, ensuring a stable webbing tension is maintained during the initial stage of operation, enhancing occupant protection and safety by mitigating peak tension values and maintaining consistent frictional resistance.
Implementation Method 1
a deformation portion, such as rubber, elastomer resin, or foam metal, is introduced between the spindle and the second energy absorbing member, which absorbs impact by deforming when the spindle rotates
Implementation Method 2
The deformation portion effectively suppresses unstable load variation, ensuring a stable webbing tension is maintained during the initial stage of operation, enhancing occupant protection and safety by mitigating peak tension values and maintaining consistent frictional resistance
Data Source
Figure 1
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AI summary
A seatbelt device 10 includes: a first energy absorbing member 12 which has two axial direction end portions 12a, 12b attached respectively to a spindle 13 and a lock member 15, and absorbs energy by undergoing twisting deformation when a load of at least a predetermined value acts on the spindle 13 while the lock member 15 is locked during an emergency; and a second energy absorbing member 50 which is fixed to the spindle 13 at one end portion 50a, is accommodated in a bend route 20 provided in the lock member 15, and absorbs energy by passing through the bend route 20 so as to undergo plastic deformation when the spindle 13 rotates. A deformation portion 19 is interposed between a turned back portion 50b of the second energy absorbing member 50 and the spindle 13. With this constitution, unstable load variation can be suppressed in an initial stage of an operation, and as a result, a stable tension can be applied to a webbing such that an occupant can be protected effectively and safely.