Variable Stiffness Anti-Roll Bar Mechanism
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Solution Overview
Problem
Conventional anti-roll bar mechanisms with constant effective stiffness can lead to poor comfort and reduced tire grip on uneven surfaces, particularly in no-load or low-load conditions, due to their inability to independently adjust spring rates for each wheel, resulting in unfavorable force distribution during cornering.
Innovation Solution
An anti-roll mechanism with sliding bushes that allow the lever arm sections of the anti-roll bar to vary their effective length in response to suspension movement, independently adjusting the effective spring rate for each wheel by changing the mechanical advantage and torsional stiffness based on the vehicle's load and suspension state, without the need for motors or electronic controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional anti-roll bar with constant effective stiffness is used, then the structure is simple and reliable, but the rebound behavior of the vehicle suspension deteriorates resulting in poor comfort and reduced tyre grip on uneven surfaces
Solution Approach 1:
The patent applies the dynamics principle by making the anti-roll bar's effective stiffness variable rather than constant. The lever arms are designed to slide within bushings, allowing their effective length to change dynamically based on suspension compression. When suspension compresses, the lever arm length decreases, increasing stiffness; when suspension extends, the lever arm length increases, decreasing stiffness. This dynamic adaptation improves both reliability and suspension rebound behavior.
2Ease of manufacture
If a conventional anti-roll bar with constant geometry is used, then the manufacturing is simple, but the effective spring rate cannot be independently adjusted for each wheel, resulting in unfavorable force distribution during cornering
Solution Approach 1:
The patent applies segmentation by dividing the anti-roll bar into a central transverse section and separate lever arms that can move independently within bushings. This segmentation allows each lever arm's effective length to vary independently based on its side's suspension movement, enabling independent adjustment of effective spring rates for each wheel while maintaining a relatively simple manufacturing process for each component.
Solution Approach 2:
The patent makes the lever arm lengths dynamic rather than fixed. The lever arms slide within bushings, allowing their effective length to change based on suspension compression and vehicle load. This dynamic capability enables independent adjustment of effective spring rates for each wheel during cornering and suspension travel, improving adaptability while keeping the overall structure manufacturable.
3Adaptability or versatility
If active anti-roll systems with motorized components are used, then the effective stiffness can be actively varied, but the device complexity increases with additional components and control technology
Solution Approach 1:
The patent applies self-service by designing a system that automatically adjusts its own effective stiffness without external control. The lever arms self-adjust their length within the bushings based on the suspension's compression state and vehicle load conditions. This passive, self-regulating mechanism achieves effective stiffness variation without motors, sensors, or electronic controls, maintaining simplicity while improving adaptability.
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 mechanism improves anti-roll performance by increasing stiffness during cornering and reduces stiffness during suspension extension, enhancing comfort and tire adhesion by allowing proportional force adjustments on each side of the vehicle, thereby reducing body roll and maintaining wheel contact with the road.
Implementation Method 1
sliding bushes (42L, 42R) mounted to respective longitudinal members (18, 20) of the chassis frame. Each sliding bush (42L, 42R) has an aperture (44) in which a corresponding lever arm section (38L, 38R) is received, so that the lever arm section can slide within the bush
Implementation Method 2
the bar is subjected to torsion, and the central section is twisted. The anti-roll bar resists this torsion through its stiffness, resulting in a partial connection between the movements of both wheels
Implementation Method 3
the bar is subjected to torsion, and the central section is twisted. The anti-roll bar resists this torsion through its stiffness
Implementation Method 4
vary their effective length in response to suspension movement, independently adjusting the effective spring rate for each wheel by changing the mechanical advantage and torsional stiffness
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A vehicle anti-roll mechanism 32 includes a unitary anti-roll bar 34 having a central, transversely mounted section (36, Fig. 4) and a pair of longitudinal lever arm sections (38L, 38R, Fig. 4). Sections 38 are operatively coupled to the vehicle via sliding bushes 42, so that their effective lengths are varied automatically in response to suspension movement. Compression of one wheel suspension reduces the effective length of its lever arm section 38, increasing the effective stiffness of the anti-roll bar on that side; whereas extension of the suspension has the opposite effect. In an embodiment, the vehicle has a rigid axle 24; the central section 36 of the anti-roll bar 34 is mounted to the axle 24; and the sliding bushes are pivotally mounted to the vehicle body. Advantages: rising roll stiffness under load; but wheels also keep better contact with road on droop.