Adjustable Roll Stiffness Suspension for Off-Road Vehicles
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Solution Overview
Problem
Off-road vehicles face challenges in achieving adequate roll stiffness and vertical stiffness simultaneously, leading to excessive sideways tilting and rollover risks when traversing uneven terrain, as existing solutions like anti-roll bars and active suspension systems are either ineffective or overly complex.
Innovation Solution
A suspension system with adjustable roll stiffness, featuring additional springs fastened to a double-arm lever that can be locked or adjusted by an actuator, allowing for increased vertical stiffness without raising roll stiffness, enabling larger skew angles and reduced lateral tilt angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the suspension system uses low vertical stiffness to achieve high stroke for off-road terrain, then the suspension can negotiate big surface irregularities and high grades, but the roll stiffness becomes insufficient causing excessive sideways tilting when cornering or traversing hillside
Solution Approach 1:
The suspension system is segmented into independent vertical spring elements and a separate anti-roll bar mechanism. The vertical springs (elements 1, 2) provide low vertical stiffness for high stroke capability, while the anti-roll bar (element 4) with arms (5, 6) provides dedicated roll stiffness through a separate mechanical pathway, decoupling the two functions.
Solution Approach 2:
The solution adds a dimensional aspect by introducing the anti-roll bar that operates in the lateral dimension perpendicular to the vertical spring action. The anti-roll bar creates a torsional moment around the vehicle's longitudinal axis, adding roll resistance without interfering with the vertical compression stroke of the spring elements.
2Stability of the object's composition
If anti-roll bar is applied to increase roll stiffness, then excessive sideways tilting is reduced, but the system cannot adapt to different operating conditions (off-road vs. on-road requirements)
Solution Approach 1:
The suspension system incorporates dynamic adaptability through adjustable components. The height of the anti-roll bar arms (5, 6) relative to the longitudinal axis can be adjusted, and the spring elements can be repositioned along the suspension arm, allowing the system to optimize its characteristics for different operating conditions such as on-road comfort versus off-road performance.
Solution Approach 2:
The system allows parameter changes in the suspension geometry and stiffness characteristics. By adjusting the position of spring elements and the height of anti-roll bar arms, the vertical and roll stiffness parameters can be modified to match different terrain requirements, providing versatility across on-road and off-road conditions.
3Device complexity
If the spring elements are placed at short distance from each other due to vehicle layout considerations, then the vehicle layout constraints are satisfied, but the roll stiffness becomes insufficient
Solution Approach 1:
The anti-roll bar acts as an intermediary mechanism that compensates for the insufficient roll stiffness caused by closely spaced spring elements. It provides the necessary roll resistance through its torsional action, mediating between the constraint of close spring placement and the requirement for adequate roll stability.
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 solution provides low roll stiffness for navigating large bumps and high cross slopes while maintaining adequate contact with the ground, and increases roll stiffness to counteract excessive tilting during cornering and hillside traversal.
Implementation Method 1
a suspension system with adjustable roll stiffness, featuring additional springs fastened to a double-arm lever
Implementation Method 2
fastened at one of its ends to the wheel supporting member or its guiding element (suspension arm or drive axle) and at the other end to one of the two arms of a double-arm lever, which in turn is pivotally fixed to the vehicle chassis by its third arm (bodywork or frame)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Wheel suspension system with adjustable roll stiffness obtained thanks to the use of an additional system of springs raising the vertical stiffness of the suspension system without increasing its roll stiffness. Each of the springs that constitute the system is fastened at one of its ends to the wheel supporting member or its guiding element (suspension arm or drive axle) and at the other end to one of the arms of a double-arm lever, which in turn is pivotally fixed to the vehicle chassis (bodywork or frame). The lever is provided with an additional arm, which makes it possible to fix the lever in a selected position or to release it so that the lever can freely rotate around the axis of its mounting to the vehicle chassis.