Air Suspension Pressure Balancing for Stable Steering and Braking
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Solution Overview
Problem
Air suspension systems in vehicles with air-suspended front and rear axles experience poorer steering and braking behavior due to uneven bellows pressures, leading to different wheel loads and rolling radii, which can be misinterpreted as cornering when driving straight, especially on torsion-resistant frames like buses.
Innovation Solution
The method involves comparing bellows pressures on the front axle and venting or ventilating air springs diagonally to reduce pressure differences, maintaining average chassis height and improving steering and braking behavior without significant height changes, using a predetermined differential pressure tolerance and controlled pulse sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If bellows pressures are adjusted independently on each side of the front axle to maintain chassis height, then chassis height stability is improved, but bellows pressure differences increase leading to poor steering and braking behavior
Solution Approach 1:
The patent combines the control of bellows pressures on diagonally opposite air springs by linking the shut-off valves through a control unit. When unequal bellows pressures are detected on the front axle, the system simultaneously adjusts both diagonally opposite air springs (one on front axle, one on rear axle) to maintain chassis height while equalizing front axle pressures, thereby improving steering and braking behavior.
2Ease of operation
If cross throttle valve is used to equalize pressure between front axle air springs, then steering behavior is improved, but chassis height control precision deteriorates
Solution Approach 1:
The patent replaces the mechanical cross throttle valve pressure equalization system with an electronic control system that uses sensor data from bellows pressure sensors and displacement sensors to control shut-off valves. This substitution allows for more precise control of both chassis height and bellows pressure equalization, eliminating the trade-off between steering behavior and height control precision.
3Ease of operation
If diagonal venting and ventilation of air springs is performed to reduce bellows pressure differences, then steering and braking behavior is improved, but energy consumption increases
Solution Approach 1:
The patent implements a feedback control system where bellows pressure sensors continuously monitor the pressures in all air springs, and the control unit compares these values to detect unequal pressures on the front axle. The system only activates diagonal venting and ventilation when unequal pressures are detected, and stops when pressures are equalized, thereby minimizing energy consumption while maintaining improved steering and braking behavior.
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 approach reduces bellows pressure differences on the front axle, enhancing steering and braking performance by maintaining balanced wheel loads and chassis heights, thus improving vehicle stability and reducing misinterpretation of wheel speed changes during straight driving.
Implementation Method 1
air springs arranged on both sides of each of the air-sprung vehicle axles between a chassis component and a vehicle frame, each with a compressed air-filled bellows
Implementation Method 2
each with a compressed air-filled bellows
Data Source
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AI summary
The invention relates to a method for controlling an air suspension system of a vehicle with regard to improving its steering and braking behavior, which has an air-sprung front axle and at least one air-sprung rear axle. The front axle and the rear axle each have air springs (4, 6, 8, 10) arranged between a chassis component and a vehicle frame, each with a compressed air-filled bellows (5, 7, 9, 11). The vehicle has a valve arrangement with a shut-off valve (14, 20, 38, 44) assigned to each of the air springs and combined inlet/outlet valves (24, 48) arranged upstream of the shut-off valves in groups.The vehicle also features a sensor arrangement with a displacement sensor (66, 70, 74, 78) located near each of the air springs for measuring the respective chassis height, and a pressure sensor (82, 86, 90, 94) connected to the bellows of each of the air springs for measuring the respective bellows pressure.The procedure provides that the bellows pressures of the air springs on the front axle are compared with each other, and that if a determined bellows pressure difference of the bellows pressures of the air springs of the front axle has exceeded a predetermined differential pressure tolerance, the air spring of the front axle with the higher bellows pressure of the compared bellows pressures of the air springs on the front axle, as well as the diagonally opposite air spring of the rear axle, are vented, and the air spring of the front axle with the lower bellows pressure of the compared bellows pressures of the air springs on the front axle, as well as the diagonally opposite air spring of the rear axle, are inflated.