Variable Rate Leaf Spring Suspension for Unsprung Mass Reduction
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Solution Overview
Problem
Leaf spring suspension systems, such as the Hotchkiss drive, suffer from high unsprung mass and lack independent suspension, leading to issues like vertical deflection and wind-up during heavy cornering and acceleration.
Innovation Solution
A vehicle suspension system featuring longitudinally extending chassis rails and leaf springs with actively variable spring rates, utilizing a fulcrum adaptor to modify the spring's effective length and stiffness, allowing for adaptive load distribution and improved ride dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solid axle is used in the Hotchkiss drive system, then axle control and structural simplicity are improved, but unsprung mass increases and independent suspension is lost
Solution Approach 1:
The solid axle is divided into two separate half-axles, each independently suspended. This segmentation allows each wheel to move independently while reducing the unsprung mass of each individual axle component, resolving the contradiction between axle control stability and unsprung mass reduction.
Solution Approach 2:
The suspension system transitions from a rigid solid axle to a dynamic configuration where each half-axle can move independently through variable rate springs. This dynamic adaptation allows the system to maintain control stability while reducing unsprung mass by allowing individual wheel movement.
2Device complexity
If a solid axle is used in the Hotchkiss drive system, then structural simplicity is improved, but vertical deflection and wind-up occur during heavy cornering and acceleration
Solution Approach 1:
The system uses variable rate springs that dynamically adjust their stiffness characteristics based on load conditions. During heavy cornering and acceleration, the springs provide increased resistance to vertical deflection and wind-up, while maintaining structural simplicity through the leaf spring design that adapts its mechanical properties rather than requiring complex active control systems.
Solution Approach 2:
The spring rate is made variable to change the mechanical properties of the suspension based on operating conditions. This allows the system to maintain reliability under heavy cornering and acceleration by increasing spring stiffness when needed, while preserving structural simplicity through passive mechanical adaptation rather than active control systems.
3Stability of the object's composition
If parallel leaf springs are used at each end of a solid axle, then axle control is improved with reduced power hop, but unsprung mass remains high and independent suspension is not achieved
Solution Approach 1:
The parallel leaf spring arrangement at each end of a solid axle is modified by segmenting the solid axle into separate half-axles. This allows each spring assembly to support independent half-axles, reducing unsprung mass while maintaining the axle control benefits of the parallel spring configuration.
Solution Approach 2:
The system transitions from a static solid axle to dynamic independent half-axles with variable rate springs. This allows each wheel assembly to respond independently to road conditions, reducing unsprung mass while maintaining improved axle control characteristics.
4Force
If leaf spring suspension systems are used, then load distribution is improved, but ride quality deteriorates due to high unsprung mass and lack of independent suspension
Solution Approach 1:
The leaf spring suspension system is modified by segmenting the solid axle into independent half-axles. This allows each wheel to be independently suspended while maintaining the load distribution capabilities of the leaf spring design, thereby improving ride quality without sacrificing load handling.
Solution Approach 2:
The system incorporates variable rate springs that dynamically adjust to maintain optimal ride quality under varying load conditions. The independent half-axles allow each wheel to respond to road irregularities independently, improving ride quality while the leaf spring configuration maintains effective load distribution.
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 system reduces unsprung mass and enhances ride quality by actively adjusting spring rates to adapt to varying loads, maintaining desired ride height and improving vehicle dynamics during different driving conditions.
Implementation Method 1
Leaf spring elements extending longitudinally... operatively coupled proximate ends thereof to the chassis rails and at an intermediate location to an axle assembly
Implementation Method 2
at least one leaf spring extending in a transverse direction of the vehicle, the at least one leaf spring having a spring rate that is variable
Data Source
AI summary
A suspension system for a vehicle includes a first chassis rail and a second chassis rail, each extending longitudinally in an axial direction of the vehicle. Also included is a first leaf spring element extending longitudinally in the axial direction of the vehicle, the first leaf spring element operatively coupled proximate ends thereof to the first chassis rail and at an intermediate location to an axle assembly of the vehicle. Further included is a second leaf spring element extending longitudinally in the axial direction of the vehicle, the second leaf spring element operatively coupled proximate ends thereof to the second chassis rail and at an intermediate location to the axle assembly of the vehicle. Yet further included is at least one leaf spring extending in a transverse direction of the vehicle, the at least one leaf spring having a spring rate that is actively variable.