Friction Plate Protrusions for Steering Rake Holding
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Solution Overview
Problem
Existing vehicle steering systems face challenges in meeting rake holding requirements, particularly when using friction between upper and lower jackets, due to coupled rake holding and energy absorption loads, and the long distance between the steering wheel center and the rake adjustment bolt, which complicates the design and requires additional coatings.
Innovation Solution
An adjustable steering column assembly with a locking mechanism that includes a rake bracket, cam arrangement, spacer, thrust bearing, and a friction plate with protrusions, which enhances the rake holding load by providing additional contact surfaces and improving delash characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If friction between upper and lower jackets is used to generate rake holding load, then energy absorption is achieved, but rake holding load and energy absorption load become coupled making it challenging to meet rake holding requirements
Solution Approach 1:
The patent segments the load-bearing functions by introducing a dedicated friction plate that separates rake holding load generation from energy absorption. The friction plate specifically generates rake holding load through friction between its protrusions and the rake bracket, while the cam arrangement and jacket friction handle energy absorption independently.
Solution Approach 2:
The friction plate acts as an intermediary component between the thrust bearing and the rake bracket. It transfers and generates rake holding load through its protrusions contacting the rake bracket, while allowing the cam arrangement to independently manage energy absorption through the jacket friction interface.
2Ease of operation
If the distance between the steering wheel center and the rake adjustment bolt is made long, then steering flexibility is improved, but the design becomes more challenging and requires additional coatings
Solution Approach 1:
The patent changes the friction characteristics by introducing a friction plate with specific protrusion geometry and material properties. This allows the system to achieve adequate rake holding load with the existing long bolt distance, eliminating the need for additional coatings while maintaining steering flexibility.
3Reliability
If a coating is added to the column assembly to address design challenges, then performance requirements are met, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the coating requirement from the design by introducing a friction plate with inherent friction properties. The protrusions on the friction plate generate sufficient rake holding load through friction alone, eliminating the need for additional coatings on the column assembly and simplifying manufacturing.
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 increases the rake holding load by approximately 1.5 times compared to systems without a friction plate, allowing for more precise control and stability in steering column adjustments.
Implementation Method 1
The friction plate has at least one protrusion to define a non-planar side, the at least one protrusion in contact with the rake bracket during all range of motion of the rake adjustment lever
Implementation Method 2
a cam arrangement configured to clamp and unclamp the rake bracket and the at least one jacket to selectively lock and unlock a rake position
Implementation Method 3
a thrust bearing having the rake bolt extending therethrough
Data Source
AI summary
A friction plate for a vehicle steering system is provided. The friction plate includes a plate body defining a slot for receiving a rake bolt therethrough, the plate body having a planar side. The friction plate also includes a plurality of protrusions extending from the plate body to define a non-planar region of the friction plate.