Steering Rack Ball Nut Assembly With Snap-Fit Return Tube Retention
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Solution Overview
Problem
Existing ball nut assemblies for vehicle steering gears require complex assembly methods like welding or screws, which can lead to defects such as geometry distortion and flash during the manufacturing process.
Innovation Solution
A ball nut assembly that employs a snap-fit mechanism between the ball return tube and the tube retention clip, eliminating the need for screws or welding, with the tube retention clip secured to the ball nut using retention tabs and recesses, and the tube portions connected via snap fits to secure the ball return tube between the ball nut and the clip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If welding is used to join tube portions, then the ball return tube can be manufactured, but geometry distortion occurs and manufacturing defects are created
Solution Approach 1:
The ball return tube is divided into multiple tube portions that are joined together using snap-fit connections instead of welding. This segmentation allows each portion to be manufactured separately with precise geometry, then assembled without thermal distortion or flash defects that would occur with welding.
Solution Approach 2:
The patent replaces the welding process (thermal/chemical joining method) with a mechanical snap-fit connection system. The snap-fit mechanism uses elastic deformation of engagement features to create a secure mechanical joint, eliminating the harmful thermal effects and flash associated with welding while maintaining structural integrity.
2Strength
If screws are used to secure the ball return tube, then the tube can be attached to the ball nut, but assembly complexity increases
Solution Approach 1:
The patent combines the tube retention function and the attachment mechanism into a single integrated clip component. The clip features retention tabs that engage with recesses in the ball nut, securing the ball return tube without requiring separate screws or fasteners. This merging reduces the number of parts and simplifies the assembly process while maintaining secure attachment.
Solution Approach 2:
The snap-fit connection system is designed to be self-securing, where the elastic engagement features automatically lock the tube portions and clip to the ball nut without requiring additional fastening operations. The mechanical interference fit provides inherent retention, eliminating the need for screws or other external fastening elements.
Data Source
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AI summary
A rack ball nut assembly for a vehicle steering gear has a ball nut, a ball return tube, and a tube retention clip. The ball nut has first and second recesses and the ball return tube has first and second tube portions. There is a snap fit between the first and second tube portions. The tube retention clip has first and second retention tabs. The first tab is engaged in the first recess and the second tab is engaged in the second recess. The ball return tube is secured between the ball nut and the tube retention clip.