Multi-Stage Steering Reduction Mechanism for Low Back-Drive Torque
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Solution Overview
Problem
Conventional vehicle steering systems face inefficiencies in mechanical efficiency and back-drive torque management, particularly when using power steering mechanisms, which can lead to increased driver effort and reduced control at low speeds.
Innovation Solution
A vehicle steering system incorporating a motor, belt assembly, gear assembly, rotary-linear conversion mechanism, and sector gear to transfer torque efficiently, reducing back-drive torque and providing a multi-stage reduction mechanism for generating pitman torque, while optimizing force assistance to oppose system and vehicle loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional power steering mechanism is used, then steering assistance is provided, but mechanical efficiency is reduced and back-drive torque increases
Solution Approach 1:
The steering system is divided into multiple independent transmission stages: a first reduction mechanism (planetary gear set) that reduces motor speed and increases torque, and a second reduction mechanism (another planetary gear set) that provides additional reduction. This segmentation allows each stage to be optimized for specific functions, improving overall mechanical efficiency while maintaining steering assistance.
Solution Approach 2:
A multi-stage reduction mechanism is introduced as an intermediary between the electric motor and the steering linkage. This intermediary mechanism efficiently transfers and transforms motor torque through multiple planetary gear sets, reducing back-drive torque while maintaining forward-drive efficiency, thereby resolving the contradiction between mechanical efficiency and driver effort.
2Loss of energy
If a multi-stage reduction mechanism is implemented, then mechanical efficiency improves and back-drive torque reduces, but device complexity increases
Solution Approach 1:
Two planetary gear sets are merged into a compact integrated transmission mechanism. The first and second reduction mechanisms share common structural elements and are arranged in a space-efficient configuration, reducing overall system complexity while maintaining the benefits of multi-stage reduction for improving mechanical efficiency and reducing back-drive torque.
Solution Approach 2:
The planetary gear sets are nested within each other in a compact arrangement, with the second reduction mechanism positioned inside or adjacent to the first. This nesting approach minimizes the overall footprint and structural complexity of the transmission system while achieving the required multi-stage torque multiplication and speed reduction.
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
The system enhances mechanical efficiency, reduces back-drive torque, and enables an electric motor to generate required steering torque, meeting performance and power requirements, thereby aiding drivers in steering operations.
Implementation Method 1
the belt assembly comprising a belt configured to be rotatable by the torque generated by the motor
Implementation Method 2
the gear assembly comprising one or more gears configured to be rotatable in response to rotary motion of the belt
Implementation Method 3
the rotary-linear conversion mechanism configured to convert rotary motion, caused by one or combination of rotary motion of the input shaft and the torque transferred from the motor, to linear motion
Implementation Method 4
the sector gear configured to convert the linear motion of the rotary-linear conversion mechanism to rotary motion so that the sector gear rotates the output shaft
Data Source
AI summary
A vehicle steering system comprises: an input shaft rotatable in response to an input for moving vehicle wheels; a motor generating torque to be supplied to an output shaft through a belt assembly; a gear assembly; a rotary-linear conversion mechanism, and a sector gear; and the rotary-linear conversion mechanism combining rotary motion of the input shaft and the torque transferred from the motor. The torque generated by the motor can be transferred to the output shaft through the belt assembly, the gear assembly, the rotary-linear conversion mechanism, and the sector gear, thereby improving mechanical efficiency, reducing back-drive torque, and providing a multi-stage reduction mechanism to generate required pitman torque from the motor. The combined use of the belt assembly, the gear assembly, the rotary-linear conversion mechanism, and the sector gear enables to the motor to generate required steering torque, while meeting system back-drive performance requirements and current draw power requirements.