Sensorless Fluid Pressure Determination in Vehicle Seat Pneumatic Bladders
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Solution Overview
Problem
Existing methods for determining fluid pressure in pneumatic bladders of vehicle seats are expensive and cumbersome, relying on pressure sensors, and lack adaptability to component changes.
Innovation Solution
A method that determines fluid pressure without sensors by using a valve device connected to the bladder, employing a first assignment rule to calculate fluid flow and a second assignment rule to determine pressure, allowing for adaptability to different pneumatic components and enabling the restoration of desired pressure settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used to determine fluid pressure in pneumatic bladders, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical pressure sensors with a calculation-based system that uses fluid quantity data and pneumatic model characteristics to determine fluid pressure. The control unit computes pressure values by processing fluid quantity information through assignment rules that reflect the pneumatic system's characteristics, eliminating the need for physical pressure sensing components.
Solution Approach 2:
The patent introduces fluid quantity determination as an intermediary measurement that indirectly provides pressure information. Instead of directly measuring pressure, the system measures fluid quantity (mass or volume) and uses this intermediate data combined with pneumatic model characteristics to calculate pressure values, simplifying the measurement system.
2Measurement precision
If pressure sensors are used to determine fluid pressure, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive pressure sensors with a software-based calculation system that uses inexpensive fluid quantity measurements and pre-stored pneumatic model characteristics. This approach uses cheaper components (fluid quantity sensors and computational algorithms) to achieve the same functional outcome, significantly reducing manufacturing costs.
Solution Approach 2:
The patent substitutes mechanical pressure sensing hardware with a computational system that calculates pressure from fluid quantity data. This replacement eliminates expensive sensor components while maintaining pressure determination capability through mathematical modeling and data processing.
3Reliability
If sensor-based pressure determination is used, then measurement reliability is improved, but adaptability to component changes decreases
Solution Approach 1:
The patent implements a dynamic system where pneumatic model characteristics can be updated and adapted to match actual component variations. The assignment rules and model parameters can be adjusted to reflect changes in compressors, valves, or bladders, allowing the system to maintain reliable pressure determination even when components are replaced or modified.
Solution Approach 2:
The patent uses parameter-based modeling where pneumatic system characteristics are represented by adjustable parameters in the assignment rules. When components change, the relevant parameters in the pneumatic model can be modified to reflect new component characteristics, maintaining system reliability without requiring hardware changes.
4Measurement precision
If fluid compressibility is considered in pressure determination, then measurement precision is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing pneumatic model characteristics that account for fluid compressibility effects. These pre-computed characteristics are saved in the control unit and reused during pressure determination, avoiding the need for complex real-time compressibility calculations while maintaining high accuracy.
Solution Approach 2:
The patent uses periodic updates of pneumatic model characteristics based on operating conditions. The assignment rules are updated at discrete intervals or based on trigger events, allowing the system to account for compressibility effects without requiring continuous complex calculations, thus balancing accuracy with computational efficiency.
Data Source
AI summary
A method for determining a fluid pressure in a pneumatic bladder of a pneumatic adjusting device of a vehicle seat is disclosed, wherein the pneumatic bladder is connected to a valve for the filling or emptying of the bladder with or of fluid. Fluid start pressure at the valve is provided as initial pressure for determining of the fluid pressure in the bladder. Fluid throughflow through the valve device is determined using a first assignment rule which assigns the fluid throughflow to the fluid start pressure at the valve. The fluid throughflow obtained using the first assignment rule over a predetermined period of time is summed to determine a fluid quantity that has flowed through the valve. Fluid pressure present in the bladder is determined using a second assignment rule which assigns the fluid pressure present in the bladder to the determined fluid quantity.