Vehicle Occupant Load Sensor with Extracted Amplifier
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Solution Overview
Problem
Existing occupant load sensors for vehicles face limitations in measurable range and signal amplification, making them unsuitable for integration between floor and seat fixing members, and requiring protective casing which adds weight and cost.
Innovation Solution
The occupant load sensor design includes a strain member fixed between floor and seat fixing members, with strain gauges and an amplifier case positioned parallel to the strain member, an FPC substrate connecting to the gauges and amplifier, and a resin coating for protection, allowing for precise load measurement without the need for a separate casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain sensor with a sensor substrate is used, then the load can be detected with strain of the sensor substrate, but the measurable range of the load is limited and it cannot be interposed between floor side and seat side fixing members
Solution Approach 1:
The patent extracts the amplifier from the sensor substrate and places it in a separate amplifier case, allowing the sensor to be installed between fixing members without the amplifier interfering with the measurement range or installation position
Solution Approach 2:
The patent divides the sensor system into separate components: the strain-sensitive sensor substrate for load detection and the amplifier in a separate case for signal processing, enabling independent optimization of each component's function and installation location
2Reliability
If the entire sensor substrate is enclosed in a case to protect the sensor substrate, strain detecting elements, circuit pattern and integrated circuit, then protection is provided, but weight and cost increase
Solution Approach 1:
The patent extracts the amplifier from the sensor substrate assembly and places it in a separate amplifier case, reducing the weight and complexity of the sensor assembly itself while maintaining necessary protection through selective coating rather than complete enclosure
Solution Approach 2:
The patent uses a resin coating applied to the sensor substrate as a protective layer, which provides necessary protection against environmental factors while being much lighter than a complete rigid enclosure case
3Ease of manufacture
If sensors are connected to the amplifier located at another position with signal line via terminal box, then connection is established, but signal amplification cannot occur in the vicinity of the occupant load sensor
Solution Approach 1:
The patent positions the amplifier in a separate amplifier case that is spatially separated from the sensor substrate but maintains electrical connection through the FPC substrate, allowing signal amplification to occur at an optimized location while preserving measurement precision through proper signal conditioning
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 configuration enhances the measurable range and amplifies signals closer to the load sensor, reducing weight and cost while maintaining precision in load measurement.
Implementation Method 1
a strain gauge attached to a surface of the strain member between each of the ends and the center of the strain member
Implementation Method 2
an amplifier substrate enclosed in the amplifier case and placed on an identical plane to the surface of the strain member for amplifying a signal transmitted from the strain gauge
Data Source
AI summary
An occupant load sensor for a vehicle includes a strain member, a connecting member fixed at the strain member, a strain gauge attached to the strain member, an upper bracket having a fixed portion and an attachment portion connecting each fixed portion and extending at a side of the strain member in a lateral direction of the seat, an amplifier case attached to the attachment portion and arranged in parallel with the strain member, an amplifier substrate enclosed in the amplifier case and placed on an identical plane to the strain member, an FPC substrate connected to the strain gauge and the amplifier substrate, a coating portion for coating a connection portion between the FPC substrate and the strain gauge; and a low pressure molded portion molded with a hot melt resin by low pressure molding in the amplifier case to cover the amplifier substrate and the connection portion.