Headrest Guide Shaft Eccentricity Management
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Solution Overview
Problem
Existing headrest designs face challenges in maintaining supporting rigidity while minimizing rattling and eccentricity, which can lead to increased resistance and uneven wear, particularly when the guide shafts are displaced in a manner that causes eccentric states.
Innovation Solution
The headrest incorporates a configuration with guide shafts and bearing portions where the second guide shaft is positioned shifted in both vertical and horizontal directions relative to the first guide shaft, with specific gap dimensions and shapes between insertion holes and guide shafts to absorb eccentricity, and includes rotation restricting portions to prevent rotational displacement, ensuring smooth and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap between the second guide shaft and the second bearing portion is increased to reduce contact surface pressure, then resistance force and wear are reduced, but rattling increases and supporting rigidity deteriorates
Solution Approach 1:
The patent applies different gap dimensions to different guide shafts and bearing portions based on their specific functions and positions. The first guide shaft has a smaller gap for stability, while the second guide shaft has a larger gap to accommodate eccentricity. This local differentiation allows each component to be optimized for its specific role, resolving the contradiction between wear reduction and rigidity maintenance.
Solution Approach 2:
The patent changes the gap parameter between guide shafts and bearing portions to different values based on their functional requirements. By setting the maximum gap dimension between the second insertion hole and second guide shaft to be larger than that of the first insertion hole and first guide shaft, the system accommodates eccentricity while maintaining appropriate contact for the first guide shaft, thus reducing wear where needed while preserving rigidity where required.
2Strength
If the gap between the second guide shaft and the second bearing portion is decreased to improve supporting rigidity, then rattling is reduced, but contact surface pressure increases causing early uneven wear
Solution Approach 1:
The patent recognizes that different guide shafts serve different functions and requires different gap dimensions. The second guide shaft, which is more susceptible to eccentricity, is given a larger gap to prevent excessive contact pressure and wear, while the first guide shaft maintains a smaller gap for stability. This localized quality differentiation resolves the contradiction.
Solution Approach 2:
The patent implements parameter changes by setting different maximum gap dimensions for different guide shaft-bearing portion pairs. The larger gap for the second guide shaft accommodates eccentric movement and reduces contact pressure, preventing wear, while the smaller gap for the first guide shaft maintains rigidity and reduces rattling.
3Adaptability or versatility
If the relative positional deviation between bearing portions is large, then installation flexibility is improved, but eccentric state occurs causing excessive contact surface pressure and resistance
Solution Approach 1:
The patent incorporates a larger gap dimension between the second insertion hole and second guide shaft as a preventive measure to absorb eccentricity before it causes problems. This beforehand cushioning allows for positional deviations during installation while preventing excessive contact surface pressure and resistance during operation, thus maintaining operational smoothness despite installation flexibility.
Solution Approach 2:
The larger gap acts as an intermediary that absorbs the eccentricity caused by relative positional deviation between bearing portions. This intermediary space allows the second guide shaft to move eccentrically without causing excessive contact pressure, mediating between the flexible installation requirements and the smooth operational requirements.
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 configuration enhances supporting rigidity by allowing the headrest movable portion to be displaced smoothly without excessive rattling or wear, even when eccentric states occur, thereby maintaining stability and reducing the risk of early wear on components.
Implementation Method 1
the first guide shaft and the second guide shaft are displaced while being guided in a sliding contact manner respectively by the first bearing portion and the second bearing portion
Data Source
AI summary
A headrest in one aspect of the present disclosure comprises a first frame member, a second frame member, a displacement mechanism to displace the second frame member with respect to the first frame member, a first guide shaft, a first bearing portion through which the first guide shaft is inserted, a second guide shaft, a second bearing portion through which the second guide shaft is inserted, a first fixing portion that comprises a first insertion hole into which one end of the first guide shaft is inserted, and a second fixing portion that comprises a second insertion hole into which one end of the second guide shaft is inserted.