Vehicle Seat Web Pre-tensioning and Suspension Pull-down Mechanism
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Solution Overview
Problem
Current motor vehicle seat restraint systems fail to effectively pre-tension restraint harnesses and pull down suspension seats during impending rollover or impact events, leading to inadequate occupant protection.
Innovation Solution
A device comprising an elongated housing with a piston and web guide that pre-tensions the restraint harness by displacing a web within the housing, and includes a bracket and stop member to retract the cable and pull the seat down, activated by a sensor detecting rollover or impact signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a restraint harness pre-tensioning device is implemented, then occupant protection effectiveness is improved, but device complexity increases
Solution Approach 1:
The piston is received within a cylindrical housing, and the web guide is positioned within the piston structure. The cable routing mechanism is nested within the housing, allowing multiple components to occupy the same spatial envelope and reducing overall system footprint while maintaining functionality.
Solution Approach 2:
The same piston-web guide mechanism serves dual functions: it pre-tensions the restraint harness web and simultaneously pulls down the suspension seat during impact events. This multi-functionality eliminates the need for separate mechanisms, reducing device complexity while improving occupant protection.
2Reliability
If the piston displaces the web to pre-tension the harness, then restraint effectiveness is improved, but the length of the web increases
Solution Approach 1:
The web guide acts as an intermediary element that redirects the web through a curved path within the piston housing. As the piston displaces, it pulls the web through the web guide, effectively shortening the free length of the web while maintaining the pre-tensioning force required for restraint effectiveness.
3Reliability
If the bracket slides to retract the cable, then harness pre-tensioning is improved, but device complexity increases
Solution Approach 1:
The bracket is integrated with the piston assembly, combining the cable retraction function with the existing pre-tensioning mechanism. The stop member is incorporated into the housing structure, eliminating separate components and reducing overall device complexity while maintaining harness pre-tensioning capability.
4Reliability
If the seat is pulled down during impact, then occupant safety is improved, but the force required increases
Solution Approach 1:
The restraint harness is pre-tensioned before the impact event occurs, putting the system in a state of readiness. This preliminary action reduces the additional force required during impact to pull down the seat, as the pre-tensioned harness already provides initial restraint force that assists the pull-down mechanism.
Data Source
AI summary
A device is disclosed for pre-tensioning an occupant restraint harness coupled to a seat portion of a motor vehicle seat and/or for pulling down the seat portion of the vehicle seat toward a seat base in embodiments in which the seat portion is suspended above the seat base. An elongated housing is secured to the seat portion, a web is coupled between the restraint harness or seat portion and the seat base or a support structure to which the seat base is mounted, and a piston carried by the housing defines a web guide in contact with the web between its two ends. As the piston moves along and relative to the housing in response to actuation thereof, the web guide displaces the web within the housing to pre-tension the occupant restraint harness and/or to pull the seat portion toward the seat base.