Steering Function-Equipped Hub Unit With Preloaded Bearing
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Solution Overview
Problem
Conventional steering systems for vehicles face challenges in achieving a balance between steering geometry, rigidity, size, and weight, particularly in confined chassis spaces, leading to inefficient fuel economy, uneven wheel load distribution, and vibration issues due to fixed mechanical connections and complex mechanisms.
Innovation Solution
A steering function-equipped hub unit with a steer-by-wire system that disconnects the steering input from the wheel, utilizing a preloaded rolling bearing to support the hub unit and allow independent wheel steering, enabling adjustable toe angles and improved rigidity through a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a steering device with fixed mechanical connection is used, then the structure is simple, but the steering geometry cannot be adjusted leading to poor fuel economy and wheel wear
Solution Approach 1:
The patent applies dynamics by making the steering geometry adjustable rather than fixed. The hub unit incorporates a steering mechanism that can dynamically change the toe angle of wheels based on driving conditions, allowing the system to adapt between different steering geometries (Ackermann at low speed, parallel at high speed) to optimize performance.
Solution Approach 2:
The steering function is segmented and integrated into the hub unit itself rather than using a separate centralized steering device. This segmentation allows each wheel hub to independently control its steering geometry, providing adaptability while maintaining structural efficiency through modular design.
2Power
If a large motor is used in the steering device, then the steering capability is sufficient, but the system size increases and chassis space is reduced
Solution Approach 1:
The steering mechanism is nested within the hub unit structure, with the motor and steering components integrated into the existing wheel hub assembly. This nesting allows the steering system to utilize the confined space within the wheel well and hub structure, avoiding the need for additional chassis space.
Solution Approach 2:
The steering function is merged with the hub unit, combining the motor, speed reducer, and steering mechanism into a single integrated assembly. This merging eliminates the need for separate steering devices and reduces the overall system volume required in the chassis.
3Manufacturing precision
If a speed reducer with large reduction ratio is provided, then the steering precision is improved, but the responsiveness decreases
Solution Approach 1:
The patent optimizes the speed reducer parameters by selecting an appropriate reduction ratio that balances precision and responsiveness. The hub unit's integrated design allows for compact speed reducer implementation with optimized gear ratios that provide sufficient steering precision while minimizing response delay through reduced inertia and faster power transmission.
4Device complexity
If the hub bearing is supported in cantilever manner, then the structure is simple, but the rigidity is reduced and steering geometry changes under acceleration
Solution Approach 1:
The patent employs asymmetric support structures for the hub bearing, using different support configurations on either side of the hub to counteract the effects of cantilever loading. This asymmetric design provides enhanced rigidity and stability under turning acceleration while maintaining structural simplicity.
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 configuration allows for independent wheel steering, reduced turning radius, enhanced stability, and improved fuel economy by dynamically adjusting steering geometry based on driving conditions, while reducing the size and weight of the steering system and minimizing unpleasant vibrations.
Implementation Method 1
the hub unit main body is supported by the unit support member through a preloaded rolling bearing
Implementation Method 2
preloaded rolling bearing to support the hub unit and allow independent wheel steering
Data Source
AI summary
Provided are a steering function-equipped hub unit that has a simple structure, high rigidity and a reduced size, a steering system, as well as a vehicle including the steering function-equipped hub unit. The steering function-equipped hub unit includes: a hub unit main body including a hub bearing supporting a wheel; a unit support member provided to a knuckle of a suspension device and rotatably supporting the hub unit main body about a turning axis extending in a vertical direction; and a steering actuator configured to rotationally drive the hub unit main body about the turning axis. The hub unit main body is supported by the unit support member through a preloaded rolling bearing.