Belt Tensioner Parallel Force Segmentation
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Solution Overview
Problem
Current seat belt tensioners with force limiting units often result in a maximum tensioning force that is considerably smaller than the release force of the force limiting unit, leading to premature release during the tensioning process, as high friction losses occur due to deflections in the seat belt strap during crashes.
Innovation Solution
A belt tensioner design where the tensioning force is divided into partial forces, with one charging the piston element and the other simultaneously charging the traction or thrust element, allowing independent adjustment of tensioning and force limiting levels, and introducing the tensioning force into the traction or thrust element past the force limiting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the force limiting unit is used to tension the seat belt strap, then the retaining force on the passenger is limited, but the maximum tensioning force that can be realized is considerably smaller than the release force of the force limiting unit due to friction losses
Solution Approach 1:
The force transmission path is segmented into two independent channels: one through the force limiting unit and another through the parallel guide element. This allows the tensioning force to be divided such that not all force must overcome friction in the force limiting unit, enabling higher maximum tensioning forces without premature release
Solution Approach 2:
The parallel guide element acts as an intermediary force transmission path that bypasses the friction losses in the force limiting unit. By guiding the traction element parallel to the force limiting unit, it provides a low-friction alternative path for force transmission, allowing the system to achieve higher tensioning forces
2Force
If the tensioning force is increased to overcome friction losses, then the maximum tensioning force increases, but the force limiting unit releases prematurely during the tensioning process
Solution Approach 1:
The force transmission is segmented into two parallel paths: one through the force limiting unit and another through the parallel guide element. This allows the system to achieve high tensioning forces through the combined action of both paths without requiring the force limiting unit to overcome all friction losses alone, preventing premature release
Solution Approach 2:
The parallel guide element provides an additional partial force transmission path that supplements the force limiting unit. This partial action through the guide element reduces the burden on the force limiting unit, allowing the system to achieve excessive tensioning forces without triggering premature release
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 enables a tensioning force in the seat belt strap that can be larger than, equal to, or marginally smaller than the release force of the force limiting unit without automatic release during the tensioning process, effectively increasing the maximum tensioning force while maintaining control over the force limiting unit.
Implementation Method 1
A belt tensioner design where the tensioning force is divided into partial forces, with one charging the piston element and the other simultaneously charging the traction or thrust element
Data Source
AI summary
A vehicle seat belt tensioner comprises a traction element that transmits a tensioning force to a seat belt strap. The traction element may be formed for example of a flexible rope or a wire, or a thrust element which can transmit traction and thrust forces. A force limiting unit, which limits the retaining force exerted by the seat belt strap on a passenger has a functional element coupled to the traction or thrust element, which is displaceable by means of a displaceable piston element in the effective direction of the tensioning force. The vehicle belt tensioner according to the invention includes means for the parallel application of tensioning force to both the piston element and the traction or thrust element, concurrently.