Seat Slide Rail Bearing Geometry for Rattle-Free Locking
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Solution Overview
Problem
Existing seat sliding devices for vehicles experience rattling and locking issues due to deviations in shaft mounting holes, leading to abnormal noise and improper locking, which are not adequately addressed by previous solutions.
Innovation Solution
A seat sliding device with a lower rail and upper rail configuration, where the upper rail has a shaft member straddling both side walls and lever member bearings with arc-shaped and flat surfaces engaging the shaft member, reducing rattling by absorbing axial displacement and maintaining proper alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shaft mounting holes are used with standard bearings, then assembly is simple and manufacturing is easy, but the shaft member deviates in the front-rear direction causing rattling and abnormal noise
Solution Approach 1:
The bearing surface contact geometry is changed from a standard configuration to an asymmetric configuration with an arc-shaped surface on one side and a flat surface on the other. This parameter change in the bearing design allows the shaft member to be positioned while accommodating manufacturing tolerances, preventing front-rear direction deviation and eliminating rattling and abnormal noise without compromising locking reliability.
2Object-generated harmful factors
If the shaft member is constrained to prevent front-rear movement, then rattling is suppressed, but the device complexity increases
Solution Approach 1:
The bearing structure itself is designed to perform the dual function of supporting the shaft member and preventing its front-rear deviation. The asymmetric bearing configuration with arc-shaped and flat surfaces creates a self-positioning mechanism that inherently constrains the shaft member without requiring additional external constraint components, thus suppressing rattling while maintaining structural simplicity.
3Ease of operation
If the lever member is made long in the front-rear direction for better operation, then operation ease is improved, but the side walls contact the upper rail causing abnormal noise
Solution Approach 1:
The bearing surface geometry is modified to create an asymmetric contact configuration that allows the lever member to operate with sufficient length for ease of use. The arc-shaped surface with radius slightly larger than the shaft member diameter, combined with the flat surface, creates proper alignment that prevents the lever member side walls from contacting the upper rail, thereby eliminating abnormal noise while maintaining operational ease.
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 effectively suppresses rattling of the upper rail in the vehicle front-rear direction when the seat is locked, ensuring secure locking and reducing noise, while allowing for free movement and assembly ease.
Implementation Method 1
a biasing member configured to bias the lock portions in a lock position direction
Implementation Method 2
Each of the left and right bearings has a surface in contact with the shaft member at one point in an up-down direction
Data Source
AI summary
A seat sliding device includes a lower rail, an upper rail, a lever member, a lock member, a biasing member and an operation member. The upper rail includes a shaft member, and the lever member includes bearings engaging with the shaft member. Each of the left and right bearings has a surface in contact with the shaft member at one point in an up-down direction by being biased by the biasing member. In the pair of left and right bearings, a surface in contact with the shaft member in one bearing is formed as an arc-shaped surface with a radius slightly larger than an outer diameter of the shaft member, and a surface in contact with the shaft member in the other bearing is formed as a flat surface extending relative to the upper rail in the longitudinal direction.