Air Bellows Pressure Estimation for Stable Suspension Control
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Solution Overview
Problem
Existing electronically controlled air suspension systems face inaccuracies in pressure regulation due to the delay in pressure equilibration between the valve block and air bellows, leading to undesired oscillations and delays in the control process, as the pressure measured at the valve block does not correspond to the actual pressure in the air bellows.
Innovation Solution
A method that determines the pressure in the air bellows using a pressure sensor located in the feed line, combined with a learning algorithm and height sensor, to calculate the bellows pressure based on a characteristic curve and ideal gas law, eliminating the need for a direct pressure sensor in the bellows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pressure sensor is placed in the feed line at the valve block to measure pressure, then the device complexity is reduced and manufacturing cost is lowered, but the measurement precision deteriorates because the measured pressure differs from the actual bellows pressure due to pressure equilibration delay
Solution Approach 1:
The patent introduces an intermediary computational model that acts as a mediator between the pressure sensor measurement and the actual bellows pressure. The model uses the measured pressure at the valve block, combines it with bellows height information, and applies a characteristic curve to calculate the actual bellows pressure. This intermediary computation resolves the contradiction by allowing the use of a simple pressure sensor location while achieving accurate bellows pressure measurement through mathematical transformation.
Solution Approach 2:
The patent replaces the mechanical solution of placing a pressure sensor directly in the bellows with a computational approach. Instead of using a complex mechanical sensor placement system that would provide direct pressure measurement, the system uses mathematical modeling and computation to derive the bellows pressure from indirect measurements, substituting a mechanical measurement problem with a computational solution.
2Ease of manufacture
If pressure measurement is taken at the valve block instead of directly in the air bellows, then the ease of manufacture is improved, but the reliability deteriorates due to offset between measured and actual pressure causing oscillations and delays
Solution Approach 1:
The patent implements a feedback mechanism where the computational model continuously adjusts the bellows pressure calculation based on the relationship between measured pressure and bellows height. The system uses feedback from multiple sensors and iteratively refines the pressure determination through the characteristic curve, ensuring reliable control despite the indirect measurement location.
Solution Approach 2:
The computational model serves as an intermediary that reconciles the discrepancy between the easily obtainable pressure measurement at the valve block and the actual bellows pressure. This intermediary computation layer maintains reliability by transforming the simple measurement into an accurate representation of bellows pressure without requiring complex sensor placement.
3Device complexity
If a pressure sensor is positioned away from the air bellows in the feed line, then the device complexity is reduced, but the loss of information increases because the instantaneous bellows pressure cannot be directly measured
Solution Approach 1:
The computational model acts as an information intermediary that recovers the lost instantaneous bellows pressure information. By combining the pressure sensor data with bellows height measurements and applying the characteristic curve, the system reconstructs the bellows pressure information that would otherwise be unavailable, preventing information loss while maintaining simple device architecture.
Solution Approach 2:
The patent creates a computational copy of the bellows pressure based on the relationship between pressure, height, and the characteristic curve. This computational copy replicates the information that would be obtained from a direct pressure measurement, allowing the system to work with indirect sensors while maintaining full information availability for control decisions.
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 method allows for reliable determination of bellows pressure without a direct pressure sensor, stabilizing the regulation process and avoiding oscillations, while adapting to actual vehicle conditions through a learning algorithm.
Implementation Method 1
a pressure measuring sensor for measuring the bellows pressure is arranged at a valve (11) arranged in a feed line (13) leading to the air bellows (1)
Implementation Method 2
a height measuring sensor for measuring a current height (h) of the air bellows (1)
Implementation Method 3
the determination of a filling pressure that can be generated by a filling process or a pressure that results from a venting process inside the air bellows takes place with the aid of a learning algorithm programmed in a computing device
Data Source
AI summary
A method is for regulating the pressure of an air bellows belonging to an air suspension, a determination of a filling pressure generatable inside the bellows by a filling process takes place with a learning algorithm as well as via a pressure and a height measuring sensor. The pressure sensor is arranged in a feed line leading to the bellows. Before opening the valve, in successive cyclic pressure and height measurements and on the basis of a characteristic curve, in which a characteristic number as a variable representative of a bellows volume V is plotted against the bellows height, a flow rate at the bellows inlet is ascertained and an air mass flow in the line between the valve and the bellows is ascertained therefrom, integrated and added to the bellows air mass. A new filling pressure is ascertained via the algorithm.