Multi-tapered Suspension Component with Constant Stress
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Solution Overview
Problem
Existing suspension components for wheeled vehicles and trailers face challenges in maintaining balanced stress distribution under vertical and lateral bending, leading to unacceptable stress concentrations and potential damage due to mismatched spring rates and load transfer in prior art designs.
Innovation Solution
The introduction of energy storing suspension components with modified tapers in width and thickness along their length, combined with low axial rate bushings, allows for constant stress distribution and increased lateral compliance, reducing load transfer to coupling assemblies and improving fatigue life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional leaf spring member is made thicker in the axle seat portion to achieve adequate vertical spring rate, then vertical load handling capability is improved, but lateral spring rate becomes significantly higher than necessary, causing unacceptable stress concentrations under lateral bending
Solution Approach 1:
The spring member is designed with varying cross-sectional properties along its length, with the axle seat portion having greater width than thickness to provide high vertical spring rate, while the limbs taper to have greater thickness than width to provide low lateral spring rate. This local differentiation of geometric properties allows each section to optimize its performance for the specific loading conditions it experiences.
Solution Approach 2:
The invention changes the geometric parameters (width and thickness) of the spring member along its length to achieve the desired spring rates. Specifically, the axle seat portion has width > thickness for vertical load handling, while the limbs have thickness > width for lateral compliance, creating a transition in mechanical properties that resolves the contradiction between vertical strength and lateral flexibility.
2Strength
If the spring member is configured with adequate vertical spring rate, then vertical disturbance isolation is improved, but lateral loads are not adequately transferred to coupling components, resulting in higher vertical stresses
Solution Approach 1:
The coupling assemblies are designed with bushings that provide lateral compliance, allowing the spring member to transfer lateral loads effectively to the chassis while maintaining the vertical spring rate needed for disturbance isolation. The bushings are strategically placed at the coupling points to enable lateral load transfer without compromising vertical performance.
Solution Approach 2:
Bushings are introduced as intermediary elements in the coupling assemblies to facilitate lateral load transfer. These bushings provide the necessary compliance and friction to transfer lateral loads from the spring member to the chassis while allowing the spring member to maintain its vertical spring rate for isolating vertical disturbances.
3Ease of operation
If a combination of bushing and lateral spring rate is configured too low, then lateral compliance is improved, but lateral loads are not adequately transferred to vertical direction, resulting in higher and potentially unacceptable vertical stresses
Solution Approach 1:
The bushings are designed with specific dimensional parameters and material properties to achieve the optimal balance between lateral compliance and vertical load transfer. The bushing geometry and material selection are tuned to provide sufficient lateral compliance for roll motion while maintaining adequate friction and structural integrity to transfer lateral loads to the vertical direction without creating excessive vertical stresses.
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 solution provides enhanced performance by maintaining constant stress in both vertical and lateral bending, improving lateral deflection capacity and reducing roll stiffness, thereby extending the lifespan of suspension components and minimizing stress on coupling assemblies.
Implementation Method 1
a pre-compressed assembly of a central body, at least one rate ring portion, and first and second elastomeric members
Implementation Method 2
bushings having high radial to axial rate ratios
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1G
AI summary
Energy storing suspension components and bushings for use in suspension systems for wheeled vehicles and trailers are disclosed. The energy storing suspension components (16) include an axle seat portion (50), an end (52) configured to include an eye (86), and a limb (54) extending between the axle seat portion and the end. The limb includes a first taper wherein the limb decreases in width as the limb extends toward the end, a second taper wherein the limb decreases in thickness as the limb extends toward the end, wherein along the limb there is at least a portion where both the first taper and second taper are present, and a third taper that is further from the axle seat portion than the first taper and wherein the limb increases in width as the limb extends toward the end. A bushing (32; 1000) is fitted in the eye (86) of the energy storing suspension component.