Vehicle Seat Rail Hook Stiffness Design
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Solution Overview
Problem
Existing vehicle seats with rail and lock devices face challenges in achieving high mechanical stiffness without increasing weight or manufacturing cost, particularly during vehicle crashes when inertia forces are applied.
Innovation Solution
The vehicle seat design incorporates upper and lower hook members made of sheet metal, which engage to prevent deformation of the rail and lock devices while allowing smooth sliding operation, and a simplified lock device structure with a cover plate and latch mechanism to enhance stiffness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rail device and lock device are designed with high mechanical stiffness to resist inertia forces during crashes, then the safety and reliability are improved, but the weight of the seat increases
Solution Approach 1:
The rail device is divided into separate upper rail and lower rail components that can slide relative to each other, while the lock device is segmented into latch, striker, and housing components. This segmentation allows each component to be optimized for its specific function rather than requiring the entire assembly to be uniformly heavy and stiff.
Solution Approach 2:
The patent changes the material parameters and structural geometry of the hook members and lock device components to achieve high stiffness-to-weight ratio. The upper and lower hook members are designed with specific thickness and curvature parameters that provide necessary stiffness while minimizing weight.
2Reliability
If the rail device and lock device are designed with high mechanical stiffness to resist inertia forces during crashes, then the safety and reliability are improved, but the manufacturing cost increases
Solution Approach 1:
By segmenting the rail and lock devices into separate functional components, each part can be manufactured using simpler, more cost-effective processes rather than requiring expensive monolithic construction of a heavily reinforced assembly.
Solution Approach 2:
The patent optimizes geometric parameters of components such as hook member thickness, rail cross-section dimensions, and lock device wall thickness to achieve the required mechanical stiffness while using minimal material, thereby reducing manufacturing cost.
3Reliability
If the upper hook member and lower hook member are made close together to prevent deformation, then the mechanical stiffness is improved, but the friction during sliding operation increases
Solution Approach 1:
The distance between the upper and lower hook members is made adjustable or variable, allowing the system to dynamically adapt between two states: a closer configuration for enhanced stiffness during crash events, and a farther configuration for smooth sliding operation during normal use.
Solution Approach 2:
The patent carefully optimizes the spacing parameter between hook members to achieve a balance where they are close enough to provide structural support and prevent deformation under load, yet far enough apart to minimize contact and friction during normal sliding movement.
Data Source
AI summary
In a vehicle seat attached to the floor of the vehicle via a rail device and a lock device, the mechanical stiffness of the rail device and the lock device is increased without increasing the overall weight of the vehicle seat and without unduly increasing the manufacturing cost. The vehicle seat further comprises at least one upper hook member (115A) depending from one of the upper rails, and at least one lower hook member (89B) extending upward from a part of the corresponding lock device or a member securing the lock device to a corresponding lower rail such that the upper and lower hook members are spaced apart from each other, but jointly prevent an upward movement of the upper rail away from the lower rail.