Nested Telescopic Lead Screw for Long-Travel Steering Columns
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Solution Overview
Problem
Conventional telescopic steering column solutions face limitations in compact adjustment and increased space requirements, particularly for vehicles with autonomous driving capabilities where greater stow travel is needed, as a single lead screw cannot accommodate the required axial travel between the dash components.
Innovation Solution
A telescopic lead screw assembly featuring a first lead screw driven by an electric actuator, a second floating lead screw with inner and outer threading, and a nut fixed to a telescope drive bracket, allowing for significant axial translation and rotation to increase stow capacity without expanding the column's spatial footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single lead screw is used for telescopic adjustment, then the device complexity is reduced, but the axial travel distance is limited by the available space between dash components
Solution Approach 1:
The patent implements a nested lead screw configuration where a second lead screw is positioned inside the first lead screw. The second lead screw has an outer threading that engages with the inner threading of the first lead screw, creating a compact nested arrangement that multiplies the axial travel distance without proportionally increasing the radial space requirements.
Solution Approach 2:
The telescopic adjustment function is divided into two independent lead screw segments that operate in series. The first lead screw provides a portion of the axial travel, while the second lead screw provides additional axial travel, allowing the system to achieve greater total displacement than a single lead screw of equivalent space.
2Adaptability or versatility
If telescopic steering columns are designed to provide greater stow travel, then the adaptability for autonomous driving applications is improved, but the space required by the steering column assembly increases
Solution Approach 1:
The nested lead screw design allows the system to achieve extended stow travel capability (exceeding 250 mm) while maintaining a compact radial footprint. The second lead screw is received within the first lead screw, ensuring that the increased axial travel does not proportionally increase the overall volume of the steering column assembly.
Solution Approach 2:
The patent focuses the increased travel capability primarily in the axial dimension through the nested lead screw mechanism, while maintaining constraints in the radial and lateral dimensions. This dimensional differentiation allows greater stow travel without expanding the steering column assembly's spatial footprint in other directions.
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 solution provides enhanced axial travel and stow capability, exceeding 250 mm, efficiently utilizing available space and overcoming limitations of single lead screw designs, suitable for various passenger vehicles and steer-by-wire applications.
Implementation Method 1
Power telescopic columns typically are actuated by a single lead screw and nut
Implementation Method 2
a first lead screw rotatably driven by an electric actuator
Data Source
AI summary
A steering column assembly includes a jacket. The assembly also includes a plurality of cylindrical lead screws threadably coupled to each other, the plurality of lead screws rotatable relative to each other and translatable relative to each other. The assembly further includes a nut threadably coupled to one of the plurality of lead screws and operatively coupled to the jacket to axially move the jacket.