Leaf Spring Force Sensor for Vehicle Seats
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Solution Overview
Problem
Existing force detection devices for vehicle seats are complex, large, and costly due to their multi-part structure, which complicates manufacturing and assembly, and they often interfere with comfort and other seat features like heating or ventilation systems.
Innovation Solution
A simplified force detection device using a single leaf spring that functions as both the bearing face and connecting rod, allowing for a compact design with a sensor placed beside the blade rather than under it, reducing height and size, and incorporating a guide mechanism for enhanced sensitivity and ease of integration within the seat's foam block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multi-part detection devices are used, then force detection capability is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the bearing face and connecting rod into a single blade element. The blade directly receives the bearing force on its surface and simultaneously transmits this force while transforming the movement direction, eliminating the need for separate components and reducing device complexity.
Solution Approach 2:
The blade serves multiple functions simultaneously: it acts as the bearing face for force application, as a connecting rod for force transmission, and as a movement transformation element. This multi-functionality reduces the number of components needed in the detection device.
2Reliability
If conventional detection devices with sensors placed under moving parts are used, then force detection is achieved, but device height increases
Solution Approach 1:
The patent changes the spatial arrangement by placing the sensor beside the blade rather than underneath it. The sensor detects the lateral displacement of the blade's distal end, transforming the detection geometry from a vertical arrangement to a horizontal one, thereby reducing device height.
3Measurement precision
If blade length is increased to improve sensitivity, then detection sensitivity improves, but device size increases
Solution Approach 1:
The patent optimizes the blade's geometric parameters, specifically setting the f/L ratio (deflection to length ratio) to less than 0.5. This parameter optimization achieves sufficient detection sensitivity with a compact blade size, balancing sensitivity requirements with space constraints.
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 reduces the device's size and complexity, enhances sensitivity, and allows for seamless integration within the seat without compromising comfort or interfering with other features, improving detection accuracy and reducing manufacturing costs.
Implementation Method 1
a blade (60) which is deformable, by elastic deformation, between a curved conformation and a more flattened conformation
Implementation Method 2
a sensor (80) which detects a displacement of the end (64) of the blade (60) in a direction perpendicular to the direction of depression
Data Source
Figure 1~5
Figure 6~10
Figure 11~14
AI summary
This device comprises: - a rigid support (50) in tension, - at least one blade (60) elastically deformable by the support force from: • a curved conformation in which the blade has a convex support face (68) on which the support force to be detected is directly exerted, • to a flatter conformation in which the convex support face is flatter, - a spring (52) capable of continuously stressing the blade towards its curved conformation, - a guide mechanism (72) mounted on the support and capable of guiding the free distal end of the blade in translation along a translation axis (38) perpendicular to the direction of penetration, - a sensor (80) capable of detecting a displacement of the free distal end along the translation axis to detect the support force.