Coplanar Amplifier in Vehicle Seat Load Sensor

Solution Overview

Problem

Existing vehicle seat load detecting devices require a large space between the upper rail and the frame to accommodate the load sensor, leading to inefficiencies in signal amplification and increased height, which complicates the integration of an amplifier unit.

Innovation Solution

A seat apparatus with a load detecting device that includes a strain member fixed at both ends to a floor-side and seat-side fixing member, a connecting member, strain gauges, and an amplifier unit integrated with the upper bracket, allowing for coplanar arrangement and reduced height, enabling efficient load detection and signal amplification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the load sensor includes a cylindrical sensing portion and connector arranged between the upper rail and the frame, then the load detection function is achieved, but the vertical space required increases

Engineering Contradiction:

Improveload detection accuracyVSAvoidvertical distance between upper rail and frame

Core Design Contradiction:

Measurement precisionVSLength of stationary object

Solution Approach 1:

The amplifier unit is integrated into the upper bracket structure, merging the signal amplification function with the mechanical support structure. This eliminates the need for separate amplifier housing and reduces overall vertical space requirements while maintaining load detection accuracy through the strain gauges on the strain member.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The amplifier unit is arranged in the lateral direction along the attachment portion of the upper bracket rather than extending vertically. This dimensional reorientation allows the amplifier to be positioned without increasing the vertical dimension between the upper rail and frame, effectively using horizontal space instead.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Power

If the amplifier unit is provided separately and connected via communication line, then signal amplification is achieved, but the device complexity and space requirements increase

Engineering Contradiction:

Improvesignal amplification capabilityVSAvoidnumber of separate components and connections

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The amplifier unit is integrated into the upper bracket structure, merging the signal amplification function with the mechanical support structure. This eliminates the need for separate amplifier housing and reduces overall vertical space requirements while maintaining load detection accuracy through the strain gauges on the strain member.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If the amplifier unit is positioned away from the load sensor, then the load sensor structure is simplified, but signal transmission efficiency decreases

Engineering Contradiction:

Improveload sensor structure simplicityVSAvoidsignal transmission efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The amplifier unit is arranged in the lateral direction along the attachment portion of the upper bracket rather than extending vertically. This dimensional reorientation allows the amplifier to be positioned without increasing the vertical dimension between the upper rail and frame, effectively using horizontal space instead.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 vertical dimension between the upper rail and the seat frame, allowing for accurate load measurement and efficient signal amplification, while maintaining the ability to control airbag deployment based on occupant weight.

Implementation Method 1

strain gauges attached on a surface of the strain member; a second strain gauge attached between the intermediate portion of the strain member and the other one of the both ends of the strain member on the surface of the strain member

Methodology Applied

Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentUS7559249B2Seat apparatus for a vehicle

Publication Date: 2009.07.14 AISIN SEIKI KK

AI summary

A seat apparatus for a vehicle has a load detecting device arranged between a floor-side fixing member adapted to be fixed to a floor of the vehicle and a seat-side fixing member adapted to be fixed to a seat for the vehicle and for measuring a load of an occupant seated on the seat. The load detecting device includes: a strain member; a connecting member vertically fixed to an intermediate portion of the strain member; strain gauges attached to a surface of the strain member; an upper bracket having a first and second fixed portions both fixed to the other surface of the strain member. The upper bracket further has an attachment portion connecting the first and second fixed portions and extending in a lateral direction of the seat; and an amplifier unit attached to a surface of the attachment portion of the upper bracket corresponding to the strain member so as to be coplanar with the strain member.