Pyrotechnic Fastener Seat Pan Drop Mechanism
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Solution Overview
Problem
Current vehicle seat designs do not allow for adjustable seat pan height during impact events, which can lead to unbelted occupants contacting the roof, visor, headliner, or windshield in frontal impacts, posing safety risks.
Innovation Solution
A seat assembly with a pyrotechnic fastener attachment and swing linkage arrangement that allows the seat pan to drop vertically relative to the seat track during a frontal impact, using a pyrotechnic fastener to sever and lower the seat pan, preventing occupant contact with hard or soft surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the seat pan height is fixed in current seat designs, then the seat structure is simple and reliable, but the unbelted occupant's head may contact the roof, visor, headliner or windshield during frontal impact events
Solution Approach 1:
The seat pan height is made dynamically adjustable through a swing linkage mechanism that allows the seat pan to pivot between an initial position and a lowered position. This dynamic adjustment is triggered by a pyrotechnic fastener that severs during impact events, automatically lowering the seat pan to prevent occupant head contact with vehicle surfaces.
Solution Approach 2:
The conventional mechanical fastening system is replaced with a pyrotechnic fastener that uses chemical energy to achieve the mechanical action of severing the linkage. This substitution allows for more reliable and calibrated deployment under impact conditions compared to traditional mechanical release mechanisms.
2Reliability
If an adjustable seat pan height mechanism is added to enhance unbelted occupant safety, then occupant protection is improved, but the seat design complexity increases
Solution Approach 1:
The seat assembly is segmented into distinct functional components: the seat pan, the swing linkage, the pyrotechnic fastener, and the calibration mechanism. This segmentation allows each component to be optimized independently and facilitates easier manufacturing and assembly while maintaining overall system reliability.
Solution Approach 2:
The system incorporates adjustable calibration parameters that allow the seat pan drop characteristics to be tuned for different impact scenarios. This parameter adjustment capability enables the same basic mechanism to provide reliable protection across various impact conditions without requiring multiple different hardware designs.
3Object-affected harmful factors
If the seat pan is made to drop vertically during impact events, then unbelted occupant head contact is prevented, but the fastener system becomes more complex
Solution Approach 1:
The pyrotechnic fastener acts as an intermediary component that translates impact detection into the mechanical action of severing the swing linkage. This intermediary element simplifies the overall control system by providing a direct chemical-to-mechanical conversion without requiring complex sensors, electronics, or control logic.
Solution Approach 2:
The pyrotechnic fastener is pre-positioned and calibrated before the impact event occurs. The calibration process pre-sets the fastener's deployment characteristics so that upon impact, the seat pan drops to the correct position automatically without requiring real-time adjustment or feedback during the impact event.
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 solution provides flexible adjustment of seat pan height in impact situations, enhancing safety protection for unbelted occupants by preventing head contact with vehicle compartment surfaces.
Implementation Method 1
A pyrotechnic fastener also attaches the swing linkage to the bracket. In a frontal impact event, the pyrotechnic fastener is caused to fire thus separating the pyrotechnic fastener and allowing the swing linkage and the attached seat pan to drop vertically
Data Source
AI summary
A seat assembly including a seat pan that drops vertically in the event of a frontal impact event to help safeguard against the head of an unbelted seat occupant striking the headliner, windshield or other components of the vehicle. The seat assembly includes a seat pan attached to a seat track. The seat track further includes an attachment bracket. A swing linkage movably connects the seat pan with the seat track by a movable fastener. A slot is formed in the bracket through which at least a part of the movable fastener passes. A pyrotechnic fastener also attaches the swing linkage to the bracket. In a frontal impact event, the pyrotechnic fastener is caused to explode thus separating the pyrotechnic fastener into two parts and allowing the swing linkage and its attached seat pan to drop vertically relative to the seat track and lowering the unbelted occupant.