Dual Planetary Steering Gear for Torque-Speed Balance
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Solution Overview
Problem
Existing vehicle steering apparatuses lack efficient mechanisms for providing steering assist and feedback, particularly in commercial vehicles, as they often rely on mechanical systems that do not effectively utilize electric motors and gear reduction ratios to optimize steering torque and speed.
Innovation Solution
The apparatus incorporates a dual planetary gear stage system with a reversible electric motor and a gearbox that adjusts gear reduction ratios to provide enhanced steering assist and feedback, using a controller to coordinate motor output with steering wheel input, thereby optimizing torque and speed for efficient steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single planetary gear stage is used, then the device complexity is reduced, but the steering assist and feedback performance is insufficient
Solution Approach 1:
The steering apparatus divides the gear reduction function into two separate planetary gear stages, each with distinct reduction ratios. The first planetary stage provides initial gear reduction from the electric motor, while the second planetary stage provides additional gear reduction and mechanical feedback. This segmentation allows each stage to be optimized for its specific function, achieving better overall steering assist and feedback performance compared to a single gear stage.
2Force
If higher gear reduction ratio is used, then the steering torque is increased, but the steering speed is reduced
Solution Approach 1:
The dual planetary gear stage system dynamically balances torque multiplication and speed reduction through its two-stage configuration. The first planetary stage with reduction ratio Z1 provides initial torque multiplication, while the second planetary stage with reduction ratio Z2 provides additional torque multiplication. The combined effect achieves high steering torque while maintaining acceptable steering speed through the distributed reduction across two stages.
3Ease of operation
If electric motor is integrated with gearbox, then the steering assist is improved, but the device complexity increases
Solution Approach 1:
The electric motor is directly integrated with the first planetary gear stage, eliminating the need for separate coupling mechanisms. The motor shaft is directly connected to the sun gear of the first planetary stage, creating a compact integrated assembly. This merging reduces the number of intermediate components and simplifies the overall system architecture while maintaining effective steering assist.
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 improved steering assist and feedback, enabling more precise control of steerable wheels while reducing the effort required for steering, particularly in larger vehicles, by increasing torque and reducing speed, thus enhancing the overall steering experience.
Implementation Method 1
A first planetary gear stage having a first gear reduction ratio and driven by the first output shaft
Implementation Method 2
A second planetary gear stage is driven by the first planetary gear stage and the pinion and has a second gear reduction ratio different from the first gear reduction ratio
Implementation Method 3
A pinion is disposed in meshing engagement with a rack portion of the steering member. Rotation of the steering wheel results in rotation of the pinion
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An apparatus for use in turning steerable vehicle wheels includes a steering column having a pinion connected with a vehicle steering wheel such that rotation of the steering wheel results in rotation of the pinion. An electrically powered steering unit includes an electric motor having a first output shaft rotatable about an axis. A first planetary gear stage has a first gear reduction ratio and is driven by the first output shaft. A second planetary gear stage is driven by the first planetary gear stage and the pinion and has a second gear reduction ratio different from the first gear reduction ratio. A second output shaft is driven by the second planetary gear stage and coupled to the steerable wheels such that rotation of the second output shaft affects steering of the vehicle wheels.