Vehicle Seat Bladder Sensor Layout for Accurate Occupant Weighing
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Solution Overview
Problem
Existing vehicle occupant weight estimation systems face inaccuracies due to changes in seat orientation, vehicle dynamics, and temperature effects, which can lead to incorrect deployment of airbag protection devices.
Innovation Solution
A device is designed with a pressure sensor positioned close to the bladder's center of gravity, minimizing influence from seat orientation and vehicle accelerations, and incorporating a temperature sensor directly coupled to the fluid for accurate pressure signal measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pressure sensor is positioned remotely from the bladder center of gravity, then the device complexity is reduced, but the measurement precision deteriorates due to head pressure effects from seat orientation changes
Solution Approach 1:
The pressure sensor is extracted from its conventional remote position and relocated directly to the bladder center of gravity. This extraction eliminates the fluid column between measurement points, removing the source of head pressure errors while maintaining a relatively simple overall device structure.
Solution Approach 2:
By positioning the pressure sensor at the bladder center of gravity, the system achieves an equipotential measurement point where gravitational effects are minimized. This ensures that pressure measurements remain consistent regardless of seat orientation or inclination angle changes.
2Ease of manufacture
If a pressure sensor is positioned remotely from the bladder center of gravity, then the ease of manufacture is improved, but the reliability deteriorates due to sensitivity to vehicle dynamics
Solution Approach 1:
The pressure sensor is extracted from the remote mounting position and placed at the bladder center of gravity, eliminating the fluid coupling hose that transmits vehicle dynamic effects. This improves reliability by isolating the measurement from acceleration-induced pressure variations.
Solution Approach 2:
The invention eliminates the fluid coupling hose as an intermediary between the bladder and pressure sensor. By removing this intermediate element, the system avoids the transmission of vehicle dynamic effects through the fluid column, thereby improving measurement reliability.
3Device complexity
If a temperature sensor is positioned remotely from the bladder, then the device complexity is reduced, but the measurement precision deteriorates due to temperature gradient effects
Solution Approach 1:
The temperature sensor is merged with the pressure sensor assembly and positioned in direct thermal contact with the bladder fluid. This combination ensures both sensors measure the same local temperature, eliminating gradients between measurement points and improving temperature compensation accuracy.
Solution Approach 2:
The invention eliminates thermal intermediaries (such as long fluid coupling hoses) between the temperature sensor and bladder. By placing the temperature sensor in direct contact with the bladder fluid at the same location as the pressure sensor, the system ensures accurate temperature measurement for compensation purposes.
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 reduces errors in occupant weight estimation by minimizing the impact of seat inclination, vehicle dynamics, and temperature variations, improving accuracy and reliability of airbag deployment decisions.
Implementation Method 1
The bladder is effective to retain a fluid and pressurize the fluid in response to an occupant weight upon the bladder
Implementation Method 2
The pressure sensor is configured to provide a pressure signal indicative of the occupant weight
Data Source
AI summary
A device configured to be installed in a vehicle seat for estimating an occupant weight. The device includes a bladder and a pressure sensor. The bladder is configured to define a cavity characterized as having a center of gravity. The bladder is effective to retain a fluid and pressurize the fluid in response to an occupant weight upon the bladder. The bladder is also configured to define an opening to the cavity. The pressure sensor is coupled directly to the opening in a manner effective to seal the opening and locate the pressure sensor proximate to the center of gravity. The pressure sensor provides a pressure signal indicative of the occupant weight.