Offset Steering Knuckle Assembly for Reduced Torque Steer
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Solution Overview
Problem
Existing vehicle suspension systems face challenges in minimizing torque steer and steering system sensitivity to wheel/tire/brake imbalances due to asymmetric longitudinal loads, which affect ride comfort and handling.
Innovation Solution
The implementation of an offset steering axis knuckle (OSAK) configuration that moves the steering axis closer to the wheel centerline, utilizing a double wishbone suspension system with specific bushing arrangements and joint types to reduce torque steer and steering sensitivity, allowing independent optimization of suspension and steering behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional suspension system is used with the steering axis positioned away from the wheel centerline, then the suspension structure is simpler, but torque steer and steering system sensitivity to wheel/tire/brake imbalances increase
Solution Approach 1:
The suspension system is divided into two separate knuckle components: an inner knuckle that interfaces with the control arms and defines the first axis, and a steering knuckle that interfaces with the wheel and defines the kingpin axis. This segmentation allows the steering axis to be offset from the suspension axis, reducing torque steer while maintaining structural manageability through modular design.
Solution Approach 2:
The inner knuckle acts as an intermediary component between the control arms and the steering knuckle. It transfers forces and motions while allowing the steering knuckle to be positioned with its kingpin axis offset from the wheel centerline, thereby reducing torque steer effects without requiring direct connection between the control arms and the offset steering axis.
2Object-affected harmful factors
If the steering axis is positioned away from the wheel centerline, then torque steer is reduced, but steering system sensitivity to wheel/tire/brake imbalances increases
Solution Approach 1:
By segmenting the knuckle into inner and steering portions, the system can position the kingpin axis offset from the wheel centerline to reduce sensitivity to imbalances, while the modular structure manages the complexity through separate, specialized components rather than a single complex unit.
Solution Approach 2:
The inner knuckle and steering knuckle are designed with different local qualities and functions. The inner knuckle focuses on suspension geometry and force transfer, while the steering knuckle is optimized for steering motion with its kingpin axis positioned to minimize sensitivity to wheel/tire/brake imbalances.
3Adaptability or versatility
If a double wishbone suspension is used, then suspension control is improved, but the ability to independently optimize steering behavior is limited
Solution Approach 1:
The double wishbone suspension is combined with a segmented knuckle assembly where the inner knuckle handles suspension control through its connection to the control arms, while the steering knuckle provides independent steering optimization through its offset kingpin axis. This segmentation allows both suspension and steering to be independently optimized.
Solution Approach 2:
The joint configuration allows dynamic optimization by permitting the steering knuckle to rotate about the kingpin axis independently from the suspension motion controlled by the inner knuckle. This dynamic independence enables the steering behavior to be optimized separately from the suspension characteristics.
Data Source
AI summary
A vehicle includes an assembly for providing suspension and steering for a wheel. The assembly includes an inner knuckle and a steering knuckle. The inner knuckle is coupled to an upper control arm at an upper joint and a lower control arm at a lower joint, forming a double wishbone suspension. The upper joint and the lower joint define a first axis. The steering knuckle is coupled to the inner knuckle at a steering joint that forms or otherwise defines a kingpin axis. The steering joint includes a revolute joint, a ball joint, or both. The steering knuckle is configured to be engaged with a tie-rod coupled to a steering mechanism. The kingpin axis is nearer a center of the wheel than the first axis, thus preventing or otherwise limiting torque steer. The upper and lower joints are constrained from significant steering rotation by suitable bushings, anti-steer arms, or both.