Steering Column Clamp Load Adjustment for Faster Stowing
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Solution Overview
Problem
Current steering column assemblies with constant clamp load during telescoping motion are too slow for longer columns, limiting the speed at which the column can stow, especially during transitions to autonomous or semi-autonomous driving modes.
Innovation Solution
A clamp load adjustment assembly that includes a cam element and rake bracket, allowing for a first and second clamp load at the jacket interface, reducing friction and enabling faster telescoping motion by adjusting the clamp load based on the rake position, facilitating faster stowing of the steering column.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant clamp load is applied during telescoping motion, then the column maintains stability and control, but the telescoping speed becomes too slow for longer columns
Solution Approach 1:
The clamp load is made dynamic rather than constant. The clamp load adjusting assembly automatically varies the clamp load applied to the jacket interface based on the telescopic position: higher clamp load during normal operation for stability, and reduced clamp load during telescoping motion to minimize friction and enable faster movement. This dynamic adjustment resolves the contradiction between speed and stability.
Solution Approach 2:
The clamp load parameter is changed during operation based on the telescopic position. The system transitions between different clamp load states (first clamp load for normal operation, second reduced clamp load for telescoping) to optimize performance. This parameter change allows the system to achieve both high speed during telescoping and high stability during normal operation.
2Reliability
If higher clamp load is applied to maintain control, then column stability is improved, but friction increases and prevents faster telescoping motion
Solution Approach 1:
The clamp load is dynamically adjusted based on operational mode. During telescoping motion, the clamp load is reduced to minimize friction at the jacket interface, enabling faster movement. During normal operation, the clamp load is increased to maintain stability and control. This dynamic behavior resolves the contradiction between stability and speed.
Solution Approach 2:
The clamp load parameter is varied according to the telescopic position and operational state. The system switches between a first clamp load value for stability-critical operations and a second reduced clamp load value for speed-critical telescoping operations, thereby achieving both high stability and high speed at different times.
3Speed
If constant clamp load is used, then the structure remains simple, but the telescoping speed cannot be increased for longer columns
Solution Approach 1:
The clamp load control is segmented into different operational zones. The clamp load adjusting assembly divides the telescoping range into different segments: a first range where higher clamp load is applied for stability, and a second range where reduced clamp load is applied for high-speed movement. This segmentation allows speed improvement without excessive complexity.
Solution Approach 2:
The cam element acts as an intermediary mechanism that automatically adjusts the clamp load based on the rake bracket position. Rather than requiring complex active control systems, the cam-based intermediary passively varies the clamp load through geometric transformation of the rake motion, achieving speed improvement with minimal added complexity.
4Speed
If the same motor is used for both manual and autonomous modes, then device complexity is reduced, but the stowing speed is insufficient for autonomous operations
Solution Approach 1:
The clamp load is made dynamic to enable the same motor to achieve different performance levels. During autonomous stowing operations, the clamp load is reduced to minimize friction, allowing the motor to achieve high stowing speeds without requiring a larger or more powerful actuator. This dynamic adjustment allows one motor to serve multiple performance requirements.
Solution Approach 2:
The clamp load parameter is changed during autonomous stowing operations to enable high-speed movement with the existing motor. By reducing the clamp load to a second value during telescoping, the system allows the same motor to achieve the high stowing speeds required for autonomous operations without upgrading to a larger actuator system.
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
Enables dual actuator speeds by reducing friction during telescoping, allowing the same motor to achieve faster stowing of the steering column during autonomous or semi-autonomous driving modes without the need for a larger stow actuator.
Implementation Method 1
reducing friction and enabling faster telescoping motion by adjusting the clamp load based on the rake position
Data Source
AI summary
A steering column assembly includes an upper jacket. The assembly also includes a lower jacket operatively coupled to the upper jacket, the upper and lower jackets telescopingly movable relative to each other in an automated manner, the upper and lower jackets moveable in a rake direction over a first range of rake positions and over a second range of rake positions that is outside the first range of rake positions. The assembly further includes a clamp load controlling component in contact with the lower jacket to apply a first clamp load on a jacket interface between the upper and lower jackets while the lower jacket is within the first range of rake positions, the clamp load controlling component applying a lower clamp load on the jacket interface while the lower jacket is in the second range of rake positions.