Axle Suspension Parallelogram Linkage Roll Stability
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Solution Overview
Problem
Existing axle suspensions for wheeled motor vehicles face challenges in achieving high roll moment resistance, high articulation, and low roll centre with low vertical stiffness, particularly in heavy-duty applications where roll stability is compromised due to high suspension frequencies.
Innovation Solution
The axle suspension design incorporates a vehicular frame with pivotally mounted swing arms, resilient elastomer bushings, air spring suspension, and a load transfer assembly, allowing for limited axle movement and dampening of pivotal movements, which creates a parallelogram structure to enhance roll resistance and ride quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional axle suspension designs are used, then structural simplicity is maintained, but roll moment resistance is insufficient and roll stability is compromised
Solution Approach 1:
The suspension system is divided into multiple functional components: swing arms for articulation, air springs for vertical suspension, elastomer bushings for lateral control, and a load transfer assembly for roll resistance. Each segment performs a specific function, allowing the system to achieve high roll moment resistance through coordinated action of simplified individual components
Solution Approach 2:
The patent introduces a vertical dimension to roll resistance by positioning the load transfer assembly and air springs to create a high roll centre. This dimensional change transforms the roll moment resistance mechanism from purely lateral (conventional) to a combination of lateral and vertical forces, significantly improving roll stability without proportionally increasing structural complexity
2Strength
If high suspension frequency is used, then vertical stiffness is improved, but roll stability is compromised
Solution Approach 1:
The suspension system applies different stiffness characteristics to different directions of movement: the air springs and elastomer bushings provide high vertical stiffness for ride support, while the swing arm geometry and lateral bushings provide controlled lateral compliance for roll stability. This local differentiation of stiffness properties allows simultaneous optimization of both vertical support and roll resistance
Solution Approach 2:
The system uses dynamic geometric relationships through the swing arm articulation and parallelogram linkage to automatically adjust the distribution of vertical and lateral forces during vehicle operation. During vertical motion, the air springs dominate; during roll motion, the load transfer assembly and swing arm geometry dominate, creating directionally-dependent mechanical behavior that resolves the stiffness-stability contradiction
3Strength
If roll centre is increased, then roll moment resistance is improved, but articulation is reduced
Solution Approach 1:
The swing arms serve multiple functions simultaneously: they provide the articulation mechanism for wheel travel, establish the geometric relationship that creates the high roll centre, and incorporate elastomer bushings that provide lateral compliance. This multi-functionality allows the same components to deliver both high articulation and improved roll moment resistance without trade-offs
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 provides superior roll stability, cornering, reduced side-to-side shock loads, enhanced ride characteristics, and versatility across various vehicle applications with low maintenance, while maintaining low roll centre and vertical stiffness.
Implementation Method 1
Air spring suspension is positioned between the axle and the frame wherein pivotal movement in an upward direction about the first pivot axis is dampened
Implementation Method 2
The axle is mounted toward the second end of the first swing arm and the second swing arm by underlying resilient elastomer bushings wherein limited movement of the axle is accommodated
Data Source
AI summary
An axle suspension includes a vehicular frame and first and second mounting fixtures mounted in spaced relation beneath the vehicular frame. First and second swing arms have first and second ends and are substantially parallel. The first ends are pivotally mounted to the first mounting fixture for vertical pivotal movement about a substantially horizontal first pivot axis. An axle is positioned on top of and perpendicular to the first swing arm and the second swing arm. The axle is mounted toward the second end of the first swing arm and the second swing arm by underlying resilient elastomer bushings wherein limited movement of the axle is accommodated about a substantially horizontal second pivot axis. Air spring suspension is positioned between the axle and the frame wherein pivotal movement in an upward direction about the first pivot axis is dampened.