Four Bar Link Suspension Axle Roll Control
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Solution Overview
Problem
Existing four bar link suspension systems fail to effectively utilize axle bend and twist to improve roll characteristics, leading to deficiencies in vehicle handling, particularly in heavy vehicles like truck tractors and dump trucks.
Innovation Solution
The system incorporates control arms and pivotable joints with torsional stiffness equal to or greater than the axle, allowing the axle to bend and twist during a roll event, thereby limiting the amount of roll and enhancing roll control without requiring stiffened suspension springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If springs are stiffened to increase the average roll rate, then roll control is improved, but the ability to dampen shock and isolate the sprung mass from vibrations deteriorates
Solution Approach 1:
The suspension system is divided into separate functional components: springs/dampers handle vertical motion and vibration isolation, while control arms with specific torsional stiffness handle roll control. This segmentation allows each component to optimize its function without compromising the other.
Solution Approach 2:
The control arms are designed with specific torsional stiffness properties localized to their structure, allowing them to provide roll resistance through their inherent stiffness characteristics rather than relying on spring stiffness. This local quality enables independent optimization of roll control and vibration isolation.
2Stability of the object's composition
If stabilizer bars are added to improve roll rate, then roll control is enhanced, but device complexity increases
Solution Approach 1:
The control arms perform multiple functions: they locate the axle relative to the frame, support vehicle weight, and provide roll control through their torsional stiffness. This multi-functionality eliminates the need for separate stabilizer bars, reducing overall system complexity while maintaining roll control effectiveness.
3Stability of the object's composition
If control arms are made more torsionally stiff to improve roll control, then roll rate increases, but the ability to absorb torsional forces through bending and twisting decreases
Solution Approach 1:
The torsional stiffness of the control arms is carefully selected to be equal to or greater than the torsional stiffness of the axle, creating an optimal balance. This parameter selection allows the axle to bend and twist to absorb torsional forces while the control arms provide sufficient roll resistance.
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 configuration significantly improves the average roll rate of the vehicle, providing enhanced roll control while maintaining a comfortable ride, even in the absence of stabilizer bars, by absorbing torsional forces as bending and twisting motions that do not contribute to roll events.
Implementation Method 1
torsion is applied to the stabilizer bar, which causes the stabilizer bar to bend and twist
Implementation Method 2
stabilizer bars are designed to have sufficient torsional resiliency to endure this bending and twisting motion
Implementation Method 3
pivotable joints, which facilitate relative motion between the control arms and the axle
Data Source
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AI summary
The present invention relates to a vehicle and a method for improving the roll characteristics of a vehicle. The vehicle includes an axle, a sprung mass, a first control arm, a second control arm, a third control arm, a first pivotable joint, a second pivotable joint, a third pivotable joint, and a fourth pivotable joint. The torsional stiffness of the first control arm, the second control arm, the first pivotable joint, the second pivotable joint, the third pivotable joint, and the fourth pivotable joint are substantially equal to or greater than the torsional stiffness of the axle, whereby the axle bends and twists during a sprung mass roll event in order to limit an amount of roll.