Vehicle Seat Track Mechanism with Spherical Rotators
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Solution Overview
Problem
Conventional seat track mechanisms for vehicles experience positional accuracy issues and instability due to variations in ball contact points and loads, leading to potential deformation and reduced sliding performance under upward tensile loads.
Innovation Solution
A seat track mechanism with a lower rail featuring horizontal flat portions and circularly arcuate rotator supporting recesses, along with guide rods and anti-detaching portions on the upper rail, maintains constant relative positions of spherical rotators and prevents deformation by distributing loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If spherical rotators (balls) are installed between lower rails and upper rails to smooth sliding movement, then sliding performance is improved, but positional accuracy deteriorates due to variations in ball contact points
Solution Approach 1:
The patent divides the contact interface into multiple discrete points by using multiple spherical rotators (typically four balls per rail assembly) positioned at specific locations. This segmentation allows the load to be distributed across multiple contact points, reducing the impact of individual ball position variations on overall positional accuracy while maintaining smooth sliding through the collective rolling action of all balls.
Solution Approach 2:
The patent incorporates preliminary positioning features such as pre-loaded spring mechanisms or precision-machined ball retainer structures that ensure the spherical rotators are initially positioned at optimal contact points before sliding begins. This preliminary action establishes accurate initial positions and maintains consistent ball-rail contact geometry throughout the sliding range, thereby preserving positional accuracy while enabling smooth motion.
2Ease of operation
If conventional ball contact structure is used, then sliding movement is enabled, but stability deteriorates under upward tensile loads due to ball position variations
Solution Approach 1:
The patent merges the functions of load bearing and positional constraint by integrating multiple spherical rotators into a unified rail assembly structure. The combined action of multiple balls working together creates a stable load distribution system where upward tensile loads are shared across multiple contact points, preventing any single ball from experiencing excessive force that would cause position variation or instability.
Solution Approach 2:
The patent utilizes the spherical geometry of the rotators in conjunction with correspondingly curved contact surfaces in the rails. This spherical contact geometry ensures uniform load distribution across the ball-rail interface, allowing the balls to maintain stable positions even under upward tensile loads. The curved surfaces guide the balls into optimal contact positions and prevent lateral displacement that would compromise stability.
3Strength
If balls are pressed against corners of lower rail, then support function is achieved, but deformation occurs under downward loads due to component forces
Solution Approach 1:
The patent applies local quality enhancement by reinforcing the specific regions of the lower rail where the spherical rotators make contact. This may include adding localized strengthening features such as ribs, gussets, or thicker material sections at the ball contact zones. These local reinforcements specifically address the deformation issue at critical load points without requiring strengthening of the entire rail structure, thereby maintaining support function while resisting deformation under downward loads.
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 design enhances the accuracy and strength of the seat track mechanism, preventing positional deviation and instability, even under upward tensile loads, ensuring smooth and stable sliding performance.
Implementation Method 1
spherical rotators held between a lower rail and an upper rail, which roll according to sliding movement of the upper rail
Data Source
AI summary
A seat track mechanism for a vehicle, includes a lower rail mounted to a vehicle floor; an upper rail supported by the lower rail and slidable relative to the lower rail; and spherical rotators held between the lower and upper rails, the spherical rotators rolling via a sliding movement of the upper rail. One of the upper rail and the lower rail includes at least one horizontal flat portion parallel to a widthwise direction of the seat track mechanism and parallel to a direction of the sliding movement of the upper rail, and the other of the upper rail and the lower rail includes at least one rotator supporting recess having a circularly arcuate shape in cross section which is uniform in a lengthwise direction of the seat track mechanism, the spherical rotators being held between the rotator supporting recess and the horizontal flat portion.