Electric Recirculating Ball Steering Worm Gear Torque Assist
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Solution Overview
Problem
Existing electric recirculating ball steering systems face limitations in achieving desired steering gear output due to low gear ratios and inadequate torque capacity, particularly in column electric power steering (CEPS) assist mechanisms.
Innovation Solution
An electric power steering system incorporating a worm and worm gear arrangement coupled with an auxiliary shaft and drive gear, which drives a manual recirculating ball steering gear, enhancing torque assist through additional gear arrangements to achieve higher output without increased electric motor power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a worm and worm gear arrangement is added to the electric power steering system, then the torque assist is increased, but the device complexity increases
Solution Approach 1:
The steering system is divided into distinct functional modules: an electric motor module, a first gear arrangement (worm and worm gear) module, and a second gear arrangement (bevel gears) module. Each module performs a specific function in the torque transmission chain, allowing the complex torque multiplication to be achieved through modular segmentation of the power transmission path.
Solution Approach 2:
The system transitions from a single-plane gear arrangement to a multi-dimensional gear configuration. The first gear arrangement operates in one plane while the second gear arrangement operates in a different spatial orientation, utilizing three-dimensional space to achieve cumulative torque multiplication without increasing the footprint proportionally.
2Power
If the gear ratio is increased to achieve higher steering gear output, then the torque capacity is improved, but the device complexity increases
Solution Approach 1:
The overall gear ratio is segmented into two separate gear arrangements, each providing a moderate ratio. The first gear arrangement (worm and worm gear) provides a ratio of approximately 10:1, and the second gear arrangement (bevel gears) provides an additional ratio of approximately 3:1, achieving a cumulative ratio of 30:1 without requiring a single excessively complex gear set.
Solution Approach 2:
Instead of achieving high gear ratio through a single complex planetary gear set or stacked gears in one dimension, the system uses two separate gear arrangements operating in different spatial dimensions and orientations, multiplying torques sequentially through orthogonal or angled gear interfaces.
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 provides increased available torque assist, enabling efficient electric power steering with fuel savings, simplified packaging, and support for advanced driver-assist steering functions like lane centering, while maintaining vehicle performance.
Implementation Method 1
a worm and worm gear arrangement, which drives an auxiliary shaft
Implementation Method 2
a drive gear and a driven gear in the form of bevel gears
Data Source
AI summary
An electric power steering system includes an electric motor including a motor output shaft. The system also includes a worm operatively coupled to the motor output shaft. The system further includes a worm gear in contact with the worm and operatively coupled to an auxiliary shaft. The system yet further includes a drive gear operatively coupled to the auxiliary shaft. The system also includes a driven gear in contact with the drive gear and operatively coupled to an input shaft to drive a manual recirculating ball steering gear.