Steering Column Tilt Screw Assembly Design
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Solution Overview
Problem
Existing steering column assemblies with tilt and telescoping functions face challenges in packaging within a small vehicle footprint, high manufacturing costs, and excessive stress on tilt screws due to limited space and component complexity.
Innovation Solution
A simplified steering column assembly design using a motor to actuate an elongated actuatable member, such as a tilt screw, which is threadingly engaged with a position securing member like a tilt nut and bushing, allowing for adjustable tilt and telescoping functions while reducing torque on the tilt screw and minimizing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a motor and tilt screw assembly are used to provide adjustable tilt function, then the steering column assembly achieves automated tilt adjustment, but the device complexity and footprint increase due to limited space for incorporating motors and adjustment mechanisms
Solution Approach 1:
The tilt nut is positioned within the column housing wall opening, and the bushing is positioned within the column housing, nesting components within existing structural spaces to minimize additional footprint while maintaining automated tilt adjustment functionality
Solution Approach 2:
The tilt screw longitudinal axis is oriented non-parallel to the column housing longitudinal axis, allowing the tilt mechanism to operate in a different dimensional orientation that optimizes space utilization within the column housing
2Adaptability or versatility
If traditional tilt screw assembly with nut and adjustment screw is used, then the steering column provides tilt adjustment capability, but excessive stress is placed on the tilt screw throughout the distance of travel
Solution Approach 1:
The adjustment screw is removed from the assembly entirely. The tilt nut is positioned to maintain contact with the column housing wall opening, providing automatic clearance adjustment and eliminating the need for a separate adjustment screw, thereby reducing stress concentration points on the tilt screw
Solution Approach 2:
The bushing is introduced as an intermediary component positioned within the column housing. The bushing maintains proper positioning and reduces friction between the tilt nut and column housing, distributing stress more evenly across the tilt screw throughout its travel distance
3Reliability
If multiple components (tilt screw, nut, adjustment screw, bushing) are used for tilt function, then the steering column assembly achieves reliable tilt adjustment, but manufacturing costs increase
Solution Approach 1:
The adjustment screw is eliminated from the assembly. The tilt nut incorporates integrated features for maintaining clearance and positioning, reducing the total component count and associated manufacturing costs while preserving reliable tilt adjustment functionality
Solution Approach 2:
The tilt nut is designed to perform multiple functions: threadedly engaging the tilt screw, maintaining clearance through contact with the column housing wall opening, and working with the bushing for smooth operation. This consolidation of functions into fewer components reduces manufacturing complexity and cost
4Power
If a tilt screw aligned perpendicular to motor axis is used, then the motor can effectively drive the screw for tilt adjustment, but the assembly requires more space and places greater stress on the screw threads
Solution Approach 1:
The tilt screw is oriented with its longitudinal axis non-parallel to the column housing longitudinal axis, allowing the screw to engage the motor drive while maintaining a compact arrangement that reduces overall assembly space requirements
Solution Approach 2:
The tilt screw, nut, and bushing are arranged within the column housing structure, nesting the drive mechanism within the existing housing volume to minimize the space required for effective motor-driven tilt adjustment
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 enables efficient adjustment of the steering column with reduced stress on the tilt screw and fewer parts, maintaining load alignment and allowing for a compact, cost-effective, and lightweight steering column assembly.
Implementation Method 1
The tilt screw has a threaded shank portion that is in threaded engagement with the tilt nut
Implementation Method 2
As the tilt screw rotates, the tilt nut moves along the tilt screw to thereby raise and lower the column housing relative to the mounting structure
Data Source
AI summary
A steering column assembly (10) including a mounting structure (20); a column housing (50) having a wall opening (54) and being fixed in position for upward and downward pivotal motion; a tilt screw (72) having a threaded shank and a gear; a tilt nut (80) and optionally a bushing surrounding the tilt nut positioned at least partially within and contacting a surface defining wall opening (54) and having a threaded bore adapted to receive the tilt screw, the contact between the tilt nut and the wall opening such that the load transmitted from the wall opening to the tilt nut is substantially on axis with the threaded bore; a motor (96) for raising and lowering the column housing by rotating the gear portion and causing the tilt nut to advance toward or away from the gear, causing the column housing to raise or lower, and wherein the longitudinal axis of the threaded shank can pivot fore or aft as the column housing is raised or lowered.