Switchable Air Spring Volumes for Dynamic Load Transfer
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Solution Overview
Problem
Conventional air suspension systems struggle to dynamically adjust wheel normal loads without altering ride height at an acceptable rate, which can lead to undesirable wheel slip or yaw rates, especially in off-road conditions or during various driving maneuvers.
Innovation Solution
The implementation of a Dynamic Load Transfer (DLT) function using switchable or variable volume air spring assemblies, which allow for the adjustment of air spring volumes to change wheel normal loads, thereby influencing wheel traction and vehicle dynamics, through a system that includes multiple air chambers and valves configured to control air communication and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If air pressure is adjusted to change wheel normal load, then wheel traction and vehicle dynamics are improved, but ride height changes occur
Solution Approach 1:
The air spring assembly is divided into multiple independent cavities (first cavity and second cavity) that can be selectively activated. By segmenting the air spring into separate volume chambers, the system can adjust the effective air volume independently without affecting ride height, resolving the contradiction between load adjustment and ride height stability.
Solution Approach 2:
The system dynamically switches between different cavity configurations (first cavity only, second cavity only, or both cavities) based on driving conditions. This dynamic reconfiguration allows the air spring to adapt its effective volume and spring rate in real-time, enabling wheel normal load adjustment without ride height changes.
2Force
If air pressure is increased to improve wheel normal load control, then wheel traction improves, but the response rate becomes too slow
Solution Approach 1:
The system uses periodic switching between different cavity configurations rather than continuous pressure adjustment. By alternately activating different cavities in a controlled sequence, the system achieves rapid response rates while maintaining effective wheel normal load control, overcoming the slow response limitation of traditional pressure-based systems.
3Force
If multiple cavities are used to adjust air volume, then wheel normal load control improves, but device complexity increases
Solution Approach 1:
Multiple cavities are merged into a single integrated air spring assembly that functions as one cohesive unit. The first and second cavities share common structural elements and are controlled by a unified control system, reducing overall complexity despite the multi-cavity design. This merging approach allows wheel normal load adjustment while maintaining structural simplicity.
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
Enables predictive and reactive control of wheel and vehicle dynamics without consumables, improving traction and stability by adjusting wheel normal loads based on driver inputs, vehicle data, and road conditions, thus enhancing vehicle performance and safety.
Implementation Method 1
A conventional air spring is a device that is arranged between a vehicle body and chassis, such that the air spring applies what is referred to as a 'normal load' to a respective wheel. The typical air spring has at least one working space, or cavity, that is filled with compressed air generated by a compressor.
Implementation Method 2
These changes in air spring volumes result in changes in air spring rates, which may result in changes in normal loads applied to each wheel.
Implementation Method 3
an air spring assembly may have a plurality of cavities, such that the air volume includes one or more of the cavities, and at least one valve operable for placing one or more of the plurality of cavities in fluid communication with one another.
Data Source
AI summary
An air suspension system which includes a Dynamic Load Transfer (DLT) function. DLT is a process of transferring vehicle load, or varying normal loads applied to each wheel of the vehicle, using switchable volume or variable volume air spring assemblies. Switchable or variable volume air spring assemblies have the ability to change air spring volumes, which results in changes in air spring rates, which result in changes in normal loads applied to each wheel. Changes in wheel normal loads change wheel traction (slip) and vehicle dynamics (pitch, roll, yaw displacement, rate and acceleration). Each air spring assembly may have multiple volume air chambers that are switched “on” and “off,” a variable volume air chamber, or the air spring assembly may be coupled with other air springs, or air chambers, that are switched or varied.