Steering Hub Unit Layout for Adjustable Toe Angle Control
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Solution Overview
Problem
Existing steering systems in vehicles face challenges with unbalanced wheel lateral force distribution, leading to increased travel resistance, fuel economy deterioration, and early tire wear due to fixed steering geometries, and independent rear-wheel steering mechanisms complicate the chassis structure and limit steering angle adjustments.
Innovation Solution
A steering function-equipped hub unit with a turning shaft-equipped hub bearing, unit support member, and steering actuator, allowing for independent attachment and detachment of components to the vehicle chassis, enabling arbitrary toe angle adjustments for improved steering performance and maintenance ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed steering geometry is used in a steering device, then the structure is simple and easy to manufacture, but the wheel lateral force distribution becomes unbalanced, leading to increased travel resistance, fuel economy deterioration, and early tire wear
Solution Approach 1:
The patent applies dynamics by making the steering geometry adjustable rather than fixed. The steering device can change its geometric configuration (Ackermann, parallel, or anti-Ackermann) depending on driving conditions, allowing optimal wheel lateral force distribution for both low-speed and high-speed operations, thereby improving fuel economy without sacrificing manufacturing simplicity
2Ease of operation
If Ackermann geometry is used for steering, then smooth turning is achieved in low-speed range, but the turning angle of outer wheel becomes excessively large in high-speed range
Solution Approach 1:
The patent implements dynamics by enabling the steering device to dynamically switch between different geometric configurations. At low speeds, Ackermann geometry provides smooth cornering, while at high speeds, the system transitions to parallel or anti-Ackermann geometry to prevent excessive outer wheel turning angles, optimizing performance across all speed ranges
3Force
If parallel geometry or anti-Ackermann geometry is used for steering, then cornering force is generated in direction counterbalancing centrifugal force in high-speed range, but the turning angle of inner wheel becomes excessively large in low-speed range
Solution Approach 1:
The patent applies dynamics by making the steering geometry adaptable to speed conditions. When driving at high speed, parallel or anti-Ackermann geometry generates cornering force to counterbalance centrifugal force. When driving at low speed, the system switches to Ackermann geometry to achieve smooth turning with appropriate wheel angle differences, preventing excessive inner wheel rotation
4Adaptability or versatility
If two motors are used in one wheel for independent steering control, then independent steering function is achieved, but the weight and costs increase due to increased number of motors
Solution Approach 1:
The patent merges the steering function with the existing steering device structure. Instead of adding separate motors to each wheel, the invention integrates independent steering control capability into the central steering device, which then controls both wheels coordinate. This approach achieves independent steering functionality while avoiding the weight and cost penalties of dual motors per wheel
5Adaptability or versatility
If independent suspension with rear-wheel steering mechanism is used, then rear wheels can be steered independently, but the chassis structure becomes complicated, increasing cost and reducing interior space
Solution Approach 1:
The patent makes the steering device universal by enabling it to control both front and rear wheels through a single integrated system. The steering device can operate in different modes (front-wheel steering only, rear-wheel steering only, or combined steering), eliminating the need for separate independent suspension steering mechanisms and reducing chassis complexity
Data Source
AI summary
The steering function-equipped hub unit includes: a turning shaft-equipped hub bearing including an inner ring, an outer ring, and rolling elements in double rows interposed between the inner ring and the outer ring, the turning shaft-equipped hub bearing having a turning shaft extending in a vertical direction; a unit support member rotatably supporting the turning shaft-equipped hub bearing (15) about a turning axis of the turning shaft; and a steering actuator configured to rotationally drive the turning shaft-equipped hub bearing about the turning axis (A). The unit support member and the steering actuator include a flange and an end portion, respectively, to be removably fixed to a knuckle which is a chassis frame component of a vehicle.