Vehicle Seat Occupant Load Sensor Noise Shielding

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Solution Overview

Problem

Existing occupant weight measurement devices for vehicles face challenges in precise weight measurement due to initial strain and load restraints, and are susceptible to electromagnetic noise interference, which can lead to erroneous readings and improper operations.

Innovation Solution

The occupant load sensor employs a strain member fixed at both ends with a connecting member, a strain gauge, a metal-made bracket, an amplifier substrate, and a resin-made amplifier case with a copper-foil ground pattern to effectively shield noise and amplify signals, minimizing electromagnetic interference while reducing weight and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a metal-made amplifier case is used to shield electromagnetic waves, then noise shielding performance is improved, but manufacturing cost and weight increase

Engineering Contradiction:

Improveelectromagnetic noise interferenceVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive metal amplifier case with a resin-made amplifier case, which is cheaper and lighter while achieving adequate noise shielding through the copper-foil ground pattern, thus reducing manufacturing cost

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent combines resin material for the amplifier case with a copper-foil ground pattern to achieve both cost reduction and effective electromagnetic noise shielding, creating a composite solution that balances performance and manufacturing cost

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a resin-made amplifier case is used to reduce weight and cost, then manufacturing cost and weight are reduced, but noise shielding performance deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidelectromagnetic noise interference

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a copper-foil ground pattern as an intermediary element between the resin amplifier case and the amplifier substrate, providing effective electromagnetic noise shielding while maintaining the cost and weight advantages of the resin case

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite structure combining resin material with copper-foil ground pattern, achieving both cost reduction and effective electromagnetic noise shielding by integrating two different materials with complementary properties

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If components are assembled to the rectangular frame after manufacturing, then manufacturing flexibility is improved, but initial strain and load occur reducing measurement precision

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidoccupant weight measurement accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent pre-assembles the amplifier substrate and copper-foil ground pattern to the strain member before final installation, ensuring proper positioning and preventing initial strain that would occur with post-assembly, thus maintaining measurement precision

Inventive Principle:

Principle #10Preliminary action

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 allows for precise weight measurement of vehicle occupants by reducing noise interference and minimizing component count, thereby enhancing measurement accuracy and reducing manufacturing costs.

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

Methodology Applied

Scientific EffectStrain gauge resistance change: Electrical Resistance

Implementation Method 2

One surface of the amplifier substrate being covered by the attachment portion of the metal-made bracket and the other surface thereof being covered by a metal-foil ground pattern

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS7487687B2Occupant load sensor of seat for vehicle

Publication Date: 2009.02.10 AISIN SEIKI KK

AI summary

An occupant load sensor of a seat for a vehicle includes a metal-made bracket fixed to a strain member and having an attachment portion extending in a lateral direction from the strain member, an amplifier substrate for amplifying a signal transmitted by the strain gauge. One surface of the amplifier substrate is covered by the attachment portion of the metal-made bracket and the other surface thereof is covered by a metal-foil ground pattern. The occupant load sensor further includes a resin-made amplifier case fixed to the attachment portion of the metal-made bracket and arranged in parallel to the strain member. The resin-made amplifier case houses therein the amplifier substrate.