Vehicle Seat Load Sensor Strain Member Design
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Solution Overview
Problem
Existing occupant load detecting devices for vehicles face issues with precision due to initial strain and load restraints, electromagnetic interference affecting electrical signals, and reduced sensitivity from immovable sensor substrates.
Innovation Solution
The device incorporates a strain member with strain gauges, supported by first and second supporting members and a bracket, allowing flexible deformation and precise load measurement, while minimizing space requirements with a lightweight amplifier case and reducing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor substrate is immovably fixed by fixing members, then the sensor substrate is prevented from dislocation, but the sensor substrate cannot be flexibly deformed and sensitivity is reduced
Solution Approach 1:
The patent changes the fixing members from immovable to movable, allowing them to move in the direction of applied force. This dynamic capability enables the sensor substrate to be flexibly deformed while maintaining position stability, thereby improving detection sensitivity without sacrificing positioning accuracy
Solution Approach 2:
The patent changes the mechanical parameter of the fixing members from rigid (immovable) to flexible (movable). This parameter change allows the fixing members to accommodate deformation of the sensor substrate while maintaining stable positioning, resolving the contradiction between position stability and detection sensitivity
2Object-affected harmful factors
If an aluminum-made amplifier case is used to shield electromagnetic waves, then electromagnetic interference is reduced, but the sensing portion becomes large and requires more space
Solution Approach 1:
The patent replaces the mechanical electromagnetic shielding structure (aluminum amplifier case) with an electronic filtering system. The bandpass filter electronically removes electromagnetic interference from the signal, eliminating the need for a large metal shielding case and reducing the sensing portion size
Solution Approach 2:
The patent extracts the electromagnetic shielding function from the amplifier case structure and implements it separately through electronic filtering. This separation allows the amplifier case to be minimized while maintaining electromagnetic interference protection through the bandpass filter
3Ease of manufacture
If components are assembled to the rectangular frame after manufacturing, then initial strain and load restraints occur, but measurement precision is reduced
Solution Approach 1:
The patent applies preliminary action by pre-assembling the load sensor and amplifier before mounting them to the rectangular frame. This preliminary assembly allows adjustments to be made while components are accessible, preventing initial strain and load restraints that would occur with post-assembly adjustments, thereby maintaining measurement precision
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 enables high-precision and sensitive occupant load detection without positional variations, maintaining sensitivity and reducing space requirements, while being cost-effective and less susceptible to electromagnetic interference.
Implementation Method 1
load, which corresponds to a weight of an occupant, is converted into an electrical signal by a strain gauge at a sensing portion of the load sensor
Data Source
AI summary
An occupant load detecting device of a seat for a vehicle includes a strain member arranged between a floor-side fixing member and a seat-side fixing member and having a strain gauge, a connecting member fixed to the strain member and securely connected to one of the floor-side fixing member and the seat-side fixing member, a first supporting member relatively immovably fitted into a fixing hole and fixed to an attachment surface formed at the other one of the floor-side fixing member and the seat-side fixing member to support the strain member, a second supporting member fitted into an attachment hole and fixed to the attachment surface, and a bracket including first and second fixing portions and an amplifier case fixing portion continuous with the first and second fixing portions and extending at a side of the strain member in a lateral direction of the seat.