Vehicle Seat Rail Roller Cage Inclined Geometry
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Solution Overview
Problem
Conventional vehicle seat rail systems using steel balls can cause deformations in aluminum profile rails due to excessive surface pressure, known as brinelling, which is not effectively addressed by existing technologies.
Innovation Solution
The use of a roller cage with rollers inclined at a predetermined angle, such as 45°, between upper and lower rails reduces surface pressure and increases line contact, distributing forces more evenly and reducing mechanical stresses, allowing for the use of lightweight materials like aluminum or magnesium alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel balls are used as rolling elements in aluminum profile rails, then the rail system provides adequate load bearing, but the steel balls cause deformations (brinelling) in the aluminum rails due to excessive surface pressure
Solution Approach 1:
The patent changes the geometry parameter of the rolling elements from spherical (balls) to cylindrical (rollers). This geometric parameter change fundamentally alters the contact mechanics, transforming point contact into line contact and thereby reducing surface pressure by a factor of several times while maintaining load bearing capacity
Solution Approach 2:
The patent applies different material properties to different components: aluminum alloy for the rails (to reduce weight) and steel for the rollers (to provide hardness and wear resistance). This local differentiation allows each component to be optimized for its specific function while working together in the rail system
2Strength
If steel rails are used for the rail guide, then the rails provide sufficient strength and durability, but the overall weight of the seat increases
Solution Approach 1:
The patent creates a composite system combining aluminum alloy rails with steel rollers. The aluminum rails provide lightweight structure while the steel rollers provide the necessary hardness and load bearing capability. This composite approach allows the use of lightweight materials where possible while maintaining overall system strength
Solution Approach 2:
By changing from spherical to cylindrical rolling elements, the patent enables the use of aluminum alloy rails instead of steel rails, achieving weight reduction while maintaining structural integrity through the altered contact mechanics that reduce surface pressure on the aluminum material
3Device complexity
If conventional ball bearing systems are used, then the rail guide structure is simple, but the surface pressure causes increased wear and mechanical stresses
Solution Approach 1:
The patent changes the geometric parameters of the rolling elements (from balls to rollers) which fundamentally improves wear resistance by distributing contact forces over a line rather than a point. This parameter change reduces surface pressure by several times, significantly enhancing the reliability and service life of the bearing system
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 solution significantly reduces surface pressure and mechanical stresses, enabling the use of lighter materials and reducing wear, while allowing for a 40% to 50% weight reduction in rail construction compared to steel profiles, and lowering manufacturing costs.
Implementation Method 1
a roller cage is provided with rollers as bearings between the upper and lower rails, the rollers in the roller cage being arranged inclined at a predetermined angle to the horizontal plane of the rails
Implementation Method 2
the bearing designed as a roller cage with rollers arranged at an angle in it and the resulting guideways in the upper and lower rails reduces the forces that occur and increases the contact surface (line contact) of the rollers, which means that the surface pressure that occurs is significantly reduced
Data Source
Figure 1
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AI summary
The invention relates to a longitudinal adjustment device for a vehicle seat, comprising at least one rail guide (1 to 11lll) with at least one upper rail (2 to 21lll) and a lower rail (3 to 31lll), wherein the upper rail (2 to 21lll) and lower rail (3 to 31lll) are mounted movably relative to each other via a bearing (L). According to the invention, a roller cage (13) is provided as the bearing (L) between the upper rail (2 to 21lll) and lower rail (3 to 31lll), wherein, in the roller cage (13), rollers (14) are arranged inclined at a predetermined angle with respect to the horizontal plane of the rails (2 to 21lll, 3 to 31lll) or transversely with respect to the running direction of the rails (2 to 21lll, 3 to 31lll).