Vehicle Suspension Force Decoupling via Active Actuator
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Solution Overview
Problem
Existing corner suspension systems in vehicles face a tradeoff between ride comfort and grip, with traditional systems often compromising on one aspect to enhance the other, and struggle to effectively decouple actuator forces from vehicle body accelerations at road noise/vibration frequencies, leading to grip fluctuations and discomfort.
Innovation Solution
A force decoupling system integrating tuned mass damping characteristics with active suspension components, using a controllable actuator connected via compliant elements like coil springs to decouple actuator forces from vehicle body accelerations, particularly at the wheel hop frequency range of 9-13 Hz, thereby optimizing the comfort-grip tradeoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional passive mechanical compliance elements (rubber bushings) are used with compliance levels >500 N/mm, then ride comfort is improved, but grip stability deteriorates due to inability to decouple actuator forces from body accelerations at wheel hop frequencies
Solution Approach 1:
The patent applies dynamics by making the suspension actuator controllable and active rather than passive. The actuator can dynamically adjust its behavior to decouple actuator forces from vehicle body accelerations at wheel hop frequencies (9-13 Hz), while still providing compliance for ride comfort. This dynamic control allows the system to adapt its compliance characteristics based on operating conditions.
Solution Approach 2:
The patent changes the compliance parameter from traditional high compliance (>500 N/mm) to lower compliance (20-50 N/mm) in the mechanical elements, while using active control to achieve the desired force decoupling effect. This parameter change allows the mechanical elements to be stiffer yet still provide comfort while enabling the active actuator to effectively decouple forces at specific frequency ranges.
2Stability of the object's composition
If corner suspension systems are tuned for enhanced grip, then grip stability is improved, but ride comfort deteriorates
Solution Approach 1:
The patent segments the suspension system into distinct functional components: passive mechanical compliance elements (coil springs, dampers) that provide basic ride comfort and support, and an active suspension actuator that provides targeted force decoupling at wheel hop frequencies. This segmentation allows each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
The active suspension actuator serves as an intermediary between the road wheel assembly and the vehicle body. It mediates the force transmission by actively decoupling actuator forces from body accelerations at wheel hop frequencies, allowing the system to simultaneously achieve grip stability and ride comfort that would be contradictory in a purely passive system.
3Power
If active suspension actuators are rigidly connected to the vehicle body, then actuator force control is improved, but ride comfort deteriorates due to transmission of road vibrations at wheel hop frequencies
Solution Approach 1:
The compliant mechanical elements (coil springs with 20-50 N/mm compliance) act as intermediaries between the active suspension actuator and the vehicle body. These intermediaries allow the actuator to maintain force control while filtering out road vibrations at wheel hop frequencies (9-13 Hz) before they reach the vehicle body, thus preserving ride comfort.
Solution Approach 2:
The system uses dynamic control of the active actuator to compensate for the compliance of the mechanical elements. The actuator actively adjusts its output to maintain precise force control despite the compliant connection, while the compliance itself provides passive vibration isolation at wheel hop frequencies.
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
The system improves ride comfort and suspension performance by effectively decoupling actuator forces from road vibrations, enhancing grip stability and reducing drive harshness across all road vibration frequencies, allowing for tailored comfort and grip performance.
Implementation Method 1
The present approach purposefully uses mechanically compliant elements providing a much lower or 'softer' compliance level, e.g., 20 N/mm-50 N/mm, so that resonant frequencies experienced from road vibrations approach the vehicle's wheel hop frequency
Implementation Method 2
so that resonant frequencies experienced from road vibrations approach the vehicle's wheel hop frequency, typically on the order of about 9-13 hertz (Hz)
Implementation Method 3
The force decoupling system integrates tuned mass damping characteristics with active suspension components
Implementation Method 4
The term 'wheel hop' as used herein refers to a phenomenon in which the road wheels may tend to shake or vibrate due to effects of vertical oscillation of the unsprung mass of the suspension system
Data Source
AI summary
A vehicle includes a vehicle body, a road wheel, and a suspension corner connecting the road wheel to the vehicle body. The suspension corner includes a suspension arm connected to the road wheel and to the vehicle body, and also includes a suspension force decoupling system disposed on an axis extending between the suspension arm and the vehicle body. The suspension force decoupling system includes an actuator having an actuator mass arranged on the axis that is configured to output an actuator force in opposite directions along the axis in response to an actuator control signal. The system also includes a compliant element connected along the axis to the actuator mass and one of the body and the suspension arm, and providing a predetermined level of mechanical compliance. A controller determines and generates the actuator force in response to a threshold acceleration of the vehicle body.