Vehicle Seat Rail Adjusting Device with Movable Support
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Solution Overview
Problem
Conventional adjusting devices for vehicle seats face issues with excessive free play and clearance, leading to potential Buzz, Squeak, and Rattle (BSR) problems and fatigue, particularly at extreme positions, while requiring an extended travel range with minimal rail length and maintaining stability and reliability in daily use and crash situations.
Innovation Solution
An adjusting device with a movable support member between the upper and lower rails, featuring a spacer that can be locked to the upper rail for enhanced stability, and a coupling member that controls coupling and decoupling based on the upper rail's position, allowing for extended travel range without excessive free play, using a locking feature that releases when the upper rail reaches a predetermined position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the total travel range of the upper rail is extended, then the adjustability and versatility of the vehicle seat is improved, but excessive free play or clearance occurs leading to BSR issues and fatigue
Solution Approach 1:
The end stop member is made displaceable rather than fixed, allowing it to dynamically adjust its position. The end stop can move longitudinally with the upper rail during normal adjustment operations, then be selectively positioned to define end positions. This dynamic capability allows the system to accommodate extended travel ranges while maintaining proper support and minimizing free play at extreme positions.
Solution Approach 2:
The end stop member is biased by a spring to automatically return to a predetermined position after being displaced. This self-service mechanism ensures that the end stop is always ready to define end positions without requiring manual intervention, while also accommodating the extended travel range through automatic positioning.
2Reliability
If fixed end stop members are used to define extreme positions, then the mechanical stability at end positions is improved, but the total travel range is limited
Solution Approach 1:
The end stop member transitions from a fixed position to a displaceable one, allowing it to define end positions when needed while also permitting extended travel range. The end stop can be positioned to provide mechanical stability at extreme positions, then moved out of the way to allow greater adjustment range.
Solution Approach 2:
The end stop member serves multiple functions: it defines end positions to provide mechanical stability, allows extended travel range through displacement, and can be selectively positioned based on operational needs. This multi-functionality resolves the contradiction between stability and travel range.
3Weight of moving object
If the upper rail is made light-weight, then the overall vehicle seat weight is reduced improving ease of operation, but the structural strength and stability in crash situations deteriorates
Solution Approach 1:
The adjusting device is divided into separate functional components: the upper rail, the displaceable end stop member, and the biasing spring. This segmentation allows the upper rail to be optimized for light weight while the end stop member and spring mechanism provide the necessary structural support and stability during crash situations without adding excessive weight to the rail itself.
Data Source
AI summary
A rail assembly for longitudinal adjustment of a vehicle seat comprises a lower rail (2) and an upper rail (1) movable relative to the lower rail, and a movable support member (400) disposed between the lower rail (2) and the upper rail (1), wherein the lower rail (2) comprises a stopper (210) disposed at a predetermined position of the lower rail (2), and the movable support member (400) comprises a base (40) for supporting the upper rail (1) on the lower rail (2) and a coupling member (47) for releasably coupling the movable support member (400) with the upper rail (1).The coupling member (47) can be displaced relative to the base. Movement of the movable support member (400) relative to the lower rail (2) in the longitudinal direction is stopped by the stopper (210) at the predetermined position, and displacement of the coupling member (47) relative to the base (40) is controlled by the position of the upper rail (1), for controlling a coupling and decoupling of the movable support member (400) to the upper rail (1).