Front Steering Link Layout to Minimize Toe-In Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vehicle steering systems with front differential devices and constant-velocity joints fail to adequately minimize the change in toe-in angle, especially during suspension strokes, leading to reduced steering precision and stability.
Innovation Solution
The vehicle design incorporates a link-type pitman arm structure with constant-velocity joints positioned between specific straight lines, allowing for equal or near-equal pivoting radii of tie rods, shafts, upper arms, and lower arms, which reduces the change in toe-in angle by synchronizing their pivoting radii and incorporating ball joints and metal collars to absorb tolerances, enabling a compact layout and improved steering mechanics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional steering systems with front differential devices and constant-velocity joints are used, then power transmission to front wheels is achieved, but the change in toe-in angle during suspension strokes is not adequately minimized, reducing steering precision and stability
Solution Approach 1:
The patent applies parameter changes by carefully positioning the constant-velocity joints between specific fore-aft straight lines (first straight line through left tie rod connection, second straight line through right tie rod connection) to equalize the pivoting radii of tie rods and shafts. This geometric parameter optimization minimizes toe-in angle changes during suspension movement, directly resolving the contradiction between maintaining steering precision and stabilizing toe-in angle.
Solution Approach 2:
The patent implements equipotentiality by making the pivoting radii of tie rods and shafts equal or substantially equal through strategic positioning of constant-velocity joints. This creates a balanced mechanical system where both sides of the steering mechanism operate under equivalent geometric conditions, minimizing differential toe-in angle changes and improving overall steering stability and precision.
2Stability of the object's composition
If the pivoting radii of tie rods and shafts are made equal or substantially equal by positioning constant-velocity joints between specific straight lines, then the change in toe-in angle is minimized, but the device complexity increases due to additional link arms and connectors
Solution Approach 1:
The patent applies universality by designing the link-type pitman arm structure where first and second link arms serve multiple functions: they connect the steering shaft to tie rods, position the constant-velocity joints between critical straight lines, and simultaneously equalize pivoting radii. This multi-functional design achieves toe-in angle stability without proportionally increasing complexity, as the same components accomplish multiple geometric and functional requirements.
Solution Approach 2:
The patent uses intermediary elements (first and second link arms, and connectors) as mediators between the steering shaft and tie rods. These intermediaries enable the constant-velocity joints to be positioned between the critical fore-aft straight lines, facilitating equal pivoting radii and minimal toe-in angle change. The intermediaries absorb the geometric complexity while maintaining a relatively simple overall steering mechanism structure.
3Manufacturing precision
If a link-type pitman arm structure with multiple link arms and connectors is implemented, then the pivoting radii can be equalized to minimize toe-in angle change, but the manufacturing complexity and tolerance requirements increase
Solution Approach 1:
The patent applies beforehand cushioning by incorporating ball joints and metal collars at critical connection points (between link arms and tie rods, and between second link arms and body frame) to absorb manufacturing tolerances and assembly variations. This preemptive tolerance absorption ensures that the pivoting radii remain equal or substantially equal despite normal manufacturing variations, maintaining toe-in angle stability without requiring excessively tight manufacturing tolerances.
Solution Approach 2:
The patent uses parameter changes by selecting specific connection points for constant-velocity joints between fore-aft straight lines to optimize the pivoting radius parameters. By carefully selecting these geometric parameters during design, the patent achieves equal pivoting radii that are robust to manufacturing variations, balancing manufacturing precision requirements with ease of assembly through standard tolerance ranges.
Data Source
AI summary
A vehicle includes a front differential, a pair of constant-velocity joints, and a steering mechanism. The steering mechanism includes a pitman arm, a pair of tie rods, a pair of first link arms each connecting the pitman arm with a corresponding one of the pair of tie rods, and a pair of second link arms each connecting a corresponding one of the pair of first link arms with a body frame. In a plan view, at least a portion of each constant-velocity joint is located between first and second straight lines extending in a fore-aft direction and through first and second connectors extending between the tie rods and the first link arms. The first connector, the second connector, and at least a portion of each constant-velocity joint are located between third and fourth straight lines extending between the first and second link arms.