Passenger Seat Rail Geometry for Stable Rest-to-Bed Conversion
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Solution Overview
Problem
Existing aircraft seat conversion systems from seated to lying positions often result in discomfort during the intermediate resting position due to inadequate seat back inclination, leading to passenger sliding and discomfort, and require additional actuators, increasing weight and cost.
Innovation Solution
A seat design with a seat frame that rotates and tilts using a unique trajectory of guide rails and ramps, allowing for continuous modification of seat cushion and backrest positions without additional actuators, maintaining passenger comfort and stability across seated, resting, and lying positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the seat back is inclined backward in the intermediate resting position, then passenger comfort is improved, but the passenger slides forward due to inadequate seat back inclination
Solution Approach 1:
The patent employs curved guide rails with specific radii (R1, R2, R3) that define a smooth transition trajectory for the seat cushion. This curvature enables the seat to follow a controlled arc during inclination, maintaining optimal angles that prevent passenger sliding while ensuring comfort in the intermediate resting position.
Solution Approach 2:
The seat system transitions from static positioning to dynamic continuous adjustment. The guide rails enable the seat cushion to rotate through a defined angular range (α1 to α2) with varying inclination angles, allowing the seat to adapt its position dynamically between seated and lying configurations while maintaining stability at intermediate positions.
2Adaptability or versatility
If additional actuators are installed to control seat bottom movement, then seat position control is improved, but weight and cost increase
Solution Approach 1:
The patent combines multiple functions into a single actuator system. The same actuator that controls seat back inclination also controls seat cushion position through the guide rail mechanism, eliminating the need for separate actuators and reducing overall system weight and complexity.
Solution Approach 2:
The guide rail system serves multiple functions: it guides the seat cushion movement, defines the inclination trajectory, controls the angular positions, and maintains the relationship between seat back and seat bottom. This multi-functional design eliminates the need for additional dedicated actuators for each function.
3Ease of operation
If the seat back is inclined backward, then comfort in lying position is improved, but the seat back intrudes into the space behind the seat
Solution Approach 1:
The guide rails are pre-configured with specific curves and radii that define the optimal trajectory for the seat cushion. This preliminary design ensures that as the seat back inclines to the desired angle for lying comfort, the seat cushion automatically moves forward along the predetermined path, clearing the space behind the seat before the backrest reaches its final position.
Solution Approach 2:
The curved guide rails with defined radii create a smooth arc that coordinates the forward movement of the seat cushion with the backward inclination of the seat back. This geometric constraint ensures that the seat back does not intrude into the space behind the seat while achieving the necessary inclination angle for comfortable lying position.
Data Source
AI summary
A seat, including a seat bottom for which a seat frame is supported by a base, and a seat back, the seat including a “seated” position, a “lying” position and an intermediate “resting” position. A seat plate can be moved in rotation around a rear axis located at the side of a rear edge of the seat, the seat plate being movable in rotation around a tilting axis in front of the rear axis, the seat frame is moved forward during conversion from the “seated” position to the “lying” position.An essentially horizontal rear segment. An intermediate rear segment with a downward slope greater than the slope followed by the tilting axis. An intermediate front segment with an essentially horizontal upward slope.