Seat Adjuster Locking Member Undercut Geometry
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Solution Overview
Problem
Existing seat length adjusters for vehicles do not securely lock in place, especially under mechanical stress, leading to potential unwanted movement during accidents or external forces.
Innovation Solution
A seat length adjuster with at least two rail pairs, featuring upper rails with slot-like openings and lower rails with tooth-shaped through holes, and a spring-loaded locking member with tooth-like protrusions that have undercuts, ensuring a secure, gap-free engagement to prevent movement, even under mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional locking member without undercut is used, then the device complexity is reduced, but the locking precision and freedom from play deteriorates
Solution Approach 1:
The locking member incorporates an undercut geometry that transforms the static tooth profile into a dynamic engagement system. The undercut creates a projecting edge that actively engages with the contact region during locking, transforming the locking action from passive insertion to active form-fit engagement, thereby achieving precise locking without excessive complexity
Solution Approach 2:
The undercut introduces a new geometric dimension to the toothlike protrusion by removing material to create a projecting edge. This dimensional change transforms a simple cylindrical or conical tooth into a T-shaped profile with an extended engaging edge, enabling form-fit locking that eliminates play without requiring complex multi-component mechanisms
2Reliability
If a locking member without form-fit engagement is used, then the ease of manufacture is improved, but the reliability under mechanical stress deteriorates
Solution Approach 1:
The undercut is pre-formed in the locking member during manufacturing, creating the projecting edge in advance. This preliminary geometric preparation ensures that when the locking member engages the opening, the form-fit connection is automatically established without requiring additional assembly steps or adjustments, thereby improving reliability while maintaining manufacturing simplicity
Solution Approach 2:
The invention changes the geometric parameters of the toothlike protrusion by introducing an undercut, transforming it from a simple shape to a T-shaped profile with a projecting edge. This parameter change enables the locking member to engage the contact region with form-fit connection, significantly improving reliability under mechanical stress while the undercut itself can be created through standard manufacturing processes
3Object-generated harmful factors
If the projecting edge engages the contact region with gap, then the ease of operation is improved, but the noise level increases
Solution Approach 1:
The undercut creates a localized projecting edge at a specific position on the toothlike protrusion. This local geometric modification concentrates the engagement at the projecting edge contact region, ensuring gap-free contact that eliminates noise while maintaining overall ease of operation through the spring-loaded mechanism
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 solution provides a secure, noise-free locking mechanism that maintains the seat's adjusted position during mechanical stress, preventing unwanted movement and ensuring the seat remains locked in place, enhancing safety and stability.
Implementation Method 1
at least one spring-loaded, movable, platelike locking member, which is held movably on the upper rail and which blocks a movement of the upper rail in the lower rail in a locked position
Implementation Method 2
the projecting edge resulting from the undercut on the respective tooth flank of the toothlike protrusions lies opposite the contact region in the opening and/or in the through hole and/or touches it, for example, it lies against this contact region
Data Source
AI summary
A seat length adjuster for a vehicle seat may have two rail pairs, each pair formed by an upper rail and a lower rail. The upper rail is provided with openings and the lower rail has through holes. At least one spring-loaded, movable locking member may be provided. The locking member carries toothlike protrusions on its two opposite lengthwise sides, which are movable from a released position into the locked position both into the openings and into the through holes. The openings and/or the through holes have contact regions for the toothlike protrusions of the locking member and at least some of the toothlike protrusions have a respective undercut on both tooth flanks. In the locked position a projecting edge resulting from this on the respective tooth flank lies opposite the contact region and/or touches this contact region.