Vehicle Seat Back Frame Asymmetric Frequency Design
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Solution Overview
Problem
Existing vehicle seat technologies face challenges in effectively absorbing vibration/impact energy, particularly when impacts exceed a predetermined level, as they often compromise rigidity to achieve energy absorption, leading to suboptimal performance in both front-and-rear and right-and-left directions.
Innovation Solution
A vehicle seat design featuring a back frame and cushion frame with a reclining mechanism, where the natural frequency in the right-and-left direction is lower than in the front-and-rear direction, utilizing materials like iron or carbon, and configuring the frames with varying rigidity and deformation allowing portions to optimize energy absorption without compromising overall rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the section modulus is lowered to create a deformation allowing portion, then impact energy absorption is improved, but the entire rigidity of the back frame is lowered
Solution Approach 1:
The patent applies local quality by creating a deformation allowing portion through localized heat treatment or reduced section modulus only at specific positions where deformation is desired, while other portions of the back frame maintain their original rigidity. This allows the frame to be rigid overall while having specific flexible zones for energy absorption.
Solution Approach 2:
The patent changes physical parameters (section modulus, material properties through heat treatment) at specific locations to create deformation allowing portions. By adjusting these parameters locally rather than globally, the frame achieves both rigidity and controlled deformability for impact energy absorption.
2Loss of energy
If the natural frequency in the right-and-left direction is lowered to improve vibration energy absorption, then the back frame becomes more flexible in that direction, but the overall structural stability may be compromised
Solution Approach 1:
The patent creates asymmetric rigidity distribution in the back frame by making the natural frequency in the right-and-left direction lower than in the front-and-rear direction. This asymmetric design allows selective flexibility in the right-and-left direction for vibration absorption while maintaining stability in the front-and-rear direction through higher natural frequency.
Solution Approach 2:
The patent applies local quality by configuring specific portions of the back frame (such as the upper part) to have lower rigidity and lower natural frequency in the right-and-left direction, while other portions maintain higher rigidity. This localized flexibility allows vibration energy absorption without compromising overall frame stability.
3Loss of energy
If deformation allowing portions are added to the back frame and cushion frame, then impact energy absorption is improved, but the device complexity increases
Solution Approach 1:
The patent achieves deformation allowing portions by changing material parameters (through heat treatment) or geometric parameters (section modulus) rather than adding separate components. This approach creates the desired deformability within the existing frame structure, avoiding increased device complexity.
Solution Approach 2:
The patent merges the deformation allowing function with the existing back frame and cushion frame structures by integrating heat treated portions or varied section modulus directly into the frame design, rather than adding separate deformation mechanisms. This consolidation maintains structural simplicity while achieving energy absorption.
Data Source
AI summary
A vehicle seat includes a tension structure extended on a back frame with a configuration in which a natural frequency in the right-and-left direction of the back frame is set lower than the natural frequency in the front-and-rear direction. Thereby, the structure can easily deflect in the right-and-left direction. Therefore, since an impact load larger than a predetermined level inputted in the front-and-rear direction due to front-and-rear/pitching vibration or a rear collision and the like becomes a force of deflecting the back frame in the right-and-left direction, the vibration/impact energy is consumed by that, and moreover, rearward displacement of the back frame consumes vibration/impact energy. Thus, absorbing performances of the vibration/impact energy are higher than before.