Hydraulically Coupled Off-Road Suspension With Remote Springs
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Solution Overview
Problem
Traditional off-road vehicle suspension systems face limitations such as restricted spring and damper mounting locations, limited motion ratios, and a tradeoff between wheel rate and damping rate, leading to reduced design freedom and performance.
Innovation Solution
A hydraulic suspension system that allows springs to be mounted remotely, using a hydraulic cylinder coupled between the wheel and chassis, enabling the use of larger springs and adjustable damping profiles, and incorporating a control actuator for active control over spring load and chassis attitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If springs are mounted between the chassis and suspension component in traditional locations, then the suspension structure is compact, but the spring size and spring rate options are limited
Solution Approach 1:
The suspension system is divided into separate functional components: the spring assembly is separated from the wheel assembly and connected via a hydraulic hose. This allows the spring to be mounted remotely on the chassis while the hydraulic cylinder remains at the wheel, enabling independent optimization of each component's location and size.
Solution Approach 2:
A hydraulic hose acts as an intermediary element connecting the spring assembly to the wheel assembly. This flexible conduit transmits hydraulic force while allowing spatial separation between the spring mounting location and the wheel, thereby expanding mounting location options without compromising force transmission.
2Strength
If the wheel rate is increased to support the chassis and cargo, then the chassis support capability is improved, but the suspension flexibility over rough terrain is reduced
Solution Approach 1:
The system uses a hydraulic cylinder with controllable damping characteristics that can dynamically adjust its stiffness. This allows the suspension to be firm when needed for chassis support and flexible when needed for terrain compliance, eliminating the need for a fixed wheel rate.
Solution Approach 2:
The damping rate of the hydraulic cylinder can be adjusted to change the suspension characteristics. By varying the damping parameter, the system can optimize performance for different operating conditions - stiffer damping for chassis support and softer damping for terrain compliance.
3Stability of the object's composition
If the damping rate is increased to resist chassis pitch and roll, then the chassis stability is improved, but the suspension ability to absorb bumps is reduced
Solution Approach 1:
The hydraulic cylinder incorporates adjustable damping characteristics that can dynamically respond to different motion conditions. The damping rate can be increased to resist chassis pitch and roll while allowing controlled compression for bump absorption, providing both stability and compliance as needed.
4Stability of the object's composition
If anti-roll bars are added to control chassis roll, then the chassis roll control is improved, but the spring force characteristics are adversely affected
Solution Approach 1:
The anti-roll bar function is extracted and replaced by the adjustable damping characteristics of the hydraulic cylinder. This eliminates the need for separate anti-roll bars that would add unwanted spring force, while achieving roll control through active damping adjustment.
5Adaptability or versatility
If the ride height is determined by suspension component design, then the suspension geometry is optimized, but the ride height adjustability is limited
Solution Approach 1:
The hydraulic cylinder incorporates adjustable damping and force characteristics that enable active ride height control. By adjusting the hydraulic pressure and damping settings, the ride height can be modified without changing the physical suspension geometry, providing adaptability while maintaining optimized component design.
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 hydraulic suspension system enhances controllability, comfort, and cargo capacity by allowing lower wheel rates and adjustable damping, reducing variability in wheel force, and enabling real-time adjustments to ride height and weight distribution.
Implementation Method 1
a first cylinder in the vehicle for communicating forces on a wheel to a second cylinder by way of a hydraulic hose
Implementation Method 2
a spring for creating forces on the second cylinder
Data Source
AI summary
A system and methods are provided for a suspension system of an off-road vehicle that allows the springs to be mounted remotely, in any location on the vehicle, enabling the use of spring sizes, spring rates, motion ratios, and damping profiles that would be impractical with traditional suspension designs. The suspension system includes a hydraulic cylinder coupled between a suspension component and a chassis, in lieu of a conventional spring. The hydraulic cylinder is in fluid communication with another, second hydraulic cylinder, by way of a hydraulic hose. The second hydraulic cylinder presses against a suspension spring that is in contact with a fixed spring stop, thereby transferring spring forces to the wheel. Alternatively, the spring stop may comprise a control actuator that moves, enabling active control over spring load.