Rear Suspension Bush Layout for Faster Toe Response in Cornering
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Solution Overview
Problem
Existing vehicle suspensions experience a time delay in response during cornering, leading to reduced controllability due to toe changes in the rear wheel, which are influenced by vertical force steering and roll steering, causing a long delay in toe-in direction response.
Innovation Solution
A suspension design incorporating a radius arm, radius arm bush, shock absorber, and specific bush rigidity ratios, with inclination angles θ1 and θ2, to generate damping forces and control toe changes, ensuring quicker responsiveness by suppressing toe-out direction changes and enhancing compliance steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same bushes are used at all nodes between links and body, then manufacturing is simplified, but toe control during cornering becomes insufficient
Solution Approach 1:
The patent applies different rigidity bushes at different nodes: softer bushes at front lateral link nodes and harder bushes at rear lateral link nodes. This local differentiation allows the front link to deform more easily for toe control while the rear link maintains stability, resolving the contradiction between manufacturing simplicity and toe control capability.
Solution Approach 2:
The patent introduces asymmetric bush rigidity distribution in the suspension system, with deliberately different bush characteristics at front and rear lateral links. This asymmetry enables differentiated compliance behavior that improves toe control during cornering while maintaining a relatively simple overall structure.
2Measurement precision
If rigid bushes are used to reduce compliance steering toe changes, then steering precision improves, but response time during cornering increases
Solution Approach 1:
The patent uses softer bushes at the front lateral link nodes to enable faster response and compliance steering, while using harder bushes at the rear lateral link nodes to maintain steering precision. This local quality differentiation resolves the contradiction between response time and steering precision.
3Stability of the object's composition
If bush rigidity is increased to suppress toe-out changes, then vehicle stability improves, but compliance steering effectiveness decreases
Solution Approach 1:
The patent strategically places softer bushes at front lateral link nodes to maintain compliance steering effectiveness, while placing harder bushes at rear lateral link nodes to suppress unwanted toe-out changes and maintain vehicle stability. This resolves the contradiction between stability and compliance steering effectiveness.
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 design shortens the response time to steering operations, improving vehicle accuracy and ease of driving by allowing earlier toe-in direction changes and reducing the time delay in rear wheel toe changes during cornering.
Implementation Method 1
The shock absorber is configured to generate a damping force in response to vertical motion of the housing with respect to the vehicle body
Implementation Method 2
The radius arm bush couples the radius arm to a vehicle body of the vehicle, with an elastic body in between
Data Source
AI summary
A suspension includes a housing, a radius arm, a radius arm bush, and a shock absorber. Inclination angles θ1 and θ2 satisfy ΔF·tan θ2>M·tan θ1, in which: θ1 is an inclination angle at which a straight line coupling the center of the radius arm bush to the center of a rear wheel is inclined to a horizontal line, to lower toward the rear wheel, viewed from a side of the vehicle in a steady state; θ2 is an inclination angle at which an axis of expansion and shrink of the shock absorber is inclined to a vertical direction, to allow the shock absorber's upper end to more forward from the shock absorber's lower end; M is an unsprung mass of the suspension; and ΔF is an amount of increase in a vertical load on the rear wheel from the steady state during a shrinkwise stroke of the shock absorber.