Vehicle Seat Inclined Support Wire Head Shake Reduction
Solution Overview
Problem
Conventional vehicle seat devices experience significant head shaking during sudden acceleration or off-road driving, affecting the occupant's visibility due to an mismatched reaction force direction, which is not effectively suppressed by existing designs.
Innovation Solution
A vehicle seat device with a swingable backrest and subframe system, utilizing inclined support members that generate a forward reaction force at the waist to limit head movement, combined with non-linear elastic upper support members that increase tension after an initial phase, effectively reducing head movement in all directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SB subframe is made swingable with respect to the SB main frame to increase ease of keeping posture, then the ease of operation is improved, but the stability of the head position deteriorates during sudden acceleration or off-road driving
Solution Approach 1:
The seat back is divided into an SB main frame and an SB subframe that can swing relative to each other. This segmentation allows the SB subframe to move independently to accommodate posture changes while the SB main frame remains stable, resolving the contradiction between ease of operation and head position stability.
Solution Approach 2:
The support members are designed with variable joint-to-joint distance that changes based on the swing angle of the SB subframe. As the SB subframe swings, the distance between joints of the support members changes, allowing the system to adapt to different positions while maintaining head stability through controlled reaction forces.
2Stability of the object's composition
If conventional support members are used to limit rearward movement of the SB subframe, then the rearward movement is restricted, but the reaction force direction does not match the direction needed to suppress head shaking
Solution Approach 1:
The support members are configured with asymmetric geometry where the straight line connecting the front end and rear end is inclined with respect to the reference normal line, rising toward the front. This asymmetric configuration ensures that the reaction force generated during rearward movement has a forward component that effectively suppresses head shaking while still limiting rearward movement of the SB subframe.
3Stability of the object's composition
If the support members are made rigid to effectively limit head movement, then the head stability is improved, but the ease of operation and posture adjustment is reduced
Solution Approach 1:
The support members are designed with variable joint-to-joint distance that dynamically changes as the SB subframe swings. This dynamic configuration allows the support members to be flexible during posture adjustment (allowing easy operation) while providing rigid support when needed to stabilize the head position during sudden movements.
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 design significantly reduces head movement and improves occupant visibility by stabilizing the head and torso, enhancing comfort and reducing physical burden during vibrations.
Implementation Method 1
upon application of a rearward force to the SB subframe, a reaction force that rises toward the front from the SB subframe acts near the seat occupant's waist
Implementation Method 2
the upper support member may be a non-linear elastic body, wherein the non-linear elastic body exhibits no tension in an initial phase after application of a rearward load that causes the SB subframe to move rearward with respect to the SB main frame, and wherein the non-linear elastic body increases tension after the initial phase is over
Data Source
AI summary
A vehicle seat device includes an SB main frame that is joined to a seat cushion via a reclining shaft; an SB subframe that is swingable with respect to the SB main frame at least about a roll axis; a backrest that is installed on the SB subframe; and a lower support wire and an upper support wire that limit rearward movement of the SB subframe and allow movement of the SB subframe about the roll axis. A straight line connecting between the front end and the rear end of the lower support wire is inclined with respect to a normal line so as to rise toward the front, the normal line being normal to a straight line connecting between an upper end of the SB main frame and the reclining shaft.