Steering Assembly Biasing Structure for Rack Mesh Alignment
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Solution Overview
Problem
Steering gear and rack mesh alignment errors in ball screw assisted steering systems due to ball screw torque, leading to inaccuracies in steering output.
Innovation Solution
A non-cylindrical steering member with a prismatic shape and an adjustment assembly comprising independent first and second adjustment members that apply biasing forces to orthogonal sides of the steering member to inhibit rotation, ensuring precise alignment and preventing ball-nut torque reaction forces from causing rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a ball screw is used to convert rotational input into linear steering output, then steering assistance is achieved, but ball screw torque causes rotation of the rack resulting in steering gear and rack mesh alignment errors
Solution Approach 1:
The steering member is changed from a traditional cylindrical shape to a non-cylindrical shape with flat sides. This asymmetric geometry provides specific contact surfaces for adjustment members, enabling precise control of the steering member's position and orientation to maintain accurate mesh alignment between the steering gear and rack despite ball screw torque.
Solution Approach 2:
Adjustment members are introduced as intermediary components between the housing and the non-cylindrical steering member. These adjustment members apply controlled forces to the flat sides of the steering member, acting as mediators to counteract the rotational effect of ball screw torque and maintain proper mesh alignment.
2Device complexity
If a cylindrical steering member is used, then the structure is simple, but ball-nut torque reaction forces cause rotation leading to alignment errors
Solution Approach 1:
The steering member is changed from a traditional cylindrical shape to a non-cylindrical shape with flat sides. This asymmetric geometry provides specific contact surfaces for adjustment members, enabling precise control of the steering member's position and orientation to maintain accurate mesh alignment between the steering gear and rack despite ball screw torque.
Solution Approach 2:
The adjustment members are designed to be adjustable, allowing the system to dynamically compensate for torque reaction forces. The adjustment members can be tuned to apply appropriate forces to the non-cylindrical steering member under different operating conditions, maintaining reliable alignment accuracy.
3Manufacturing precision
If adjustment members are added to apply biasing forces to the steering member, then rotation is prevented and alignment accuracy is improved, but device complexity increases
Solution Approach 1:
The adjustment assembly is segmented into multiple independent adjustment members, each responsible for applying biasing forces to specific flat sides of the non-cylindrical steering member. This segmentation allows for targeted and precise control of forces on different surfaces, improving alignment accuracy while keeping each individual adjustment member relatively simple.
Solution Approach 2:
The adjustment members serve multiple functions: they apply biasing forces to prevent rotation, provide adjustable positioning, and maintain consistent contact with the non-cylindrical steering member. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity.
Data Source
AI summary
A steering assembly includes a steering member and an adjustment assembly. The steering member has a first side, a second side adjacent the first side, a third side adjacent the second side and disposed opposite the first side, and a fourth side adjacent the third side and disposed opposite the second side. The adjustment assembly includes a first adjustment member and a second adjustment member. The first adjustment member is arranged to apply a first biasing force to the first side and a second biasing force to the second side. The second adjustment member is arranged to engage the third side and the fourth side.