Self-Retaining Ball Nut Pulley for Low-Complexity Steering Assembly
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Solution Overview
Problem
Traditional steering assemblies require fasteners to attach pulleys to rotating members, which can restrict movement and increase axial loads, but these fasteners can complicate assembly and reduce flexibility.
Innovation Solution
A steering system that uses a ball nut assembly with a self-retaining driven pulley, where the pulley is retained by integral features such as fingers and grooves, eliminating the need for separate fasteners and allowing for secure attachment without snap rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fasteners are used to attach the pulley to the rotating member, then the axial load capability is improved, but the device complexity increases due to additional components and assembly steps
Solution Approach 1:
The retaining member is integrated into the pulley structure itself, merging the attachment function with the pulley body. The finger of the retaining member engages with the groove on the rotating member, eliminating the need for separate fasteners while maintaining secure attachment and axial load capability.
Solution Approach 2:
The separate fasteners are extracted from the system and replaced with an integral retaining member. This extraction simplifies the device by removing unnecessary components while the groove and finger mechanism provides the necessary retention function.
2Reliability
If fasteners are used to secure the pulley, then the attachment reliability is improved, but the ease of manufacture deteriorates due to additional assembly steps
Solution Approach 1:
The retaining member is formed as an integral part of the pulley during manufacturing, combining multiple functions into a single component. This eliminates separate assembly steps for fasteners while maintaining reliable attachment through the finger-groove engagement mechanism.
3Strength
If traditional fasteners are used, then the axial load capability is enhanced, but the adaptability decreases due to fixed attachment points
Solution Approach 1:
The retaining member with its finger-groove engagement provides a dynamic attachment solution that can accommodate variations in positioning and orientation. The integral design allows for easier adjustment and adaptation to different configurations while maintaining secure attachment and load-bearing capability.
Data Source
AI summary
A steering system is provided. The steering system may include a drive pulley and a ball nut assembly. The drive pulley may be operatively connected to a drive shaft. The ball nut assembly may be driven by the drive pulley via a belt disposed about the drive pulley and the ball nut assembly. The ball nut assembly may include a ball nut and a driven pulley. The ball nut may have an inner surface disposed about a ball screw that defines and extends along a first axis and an outer surface disposed opposite the inner surface. The ball nut may define a first groove that extends from the outer surface towards the inner surface. The driven pulley may be disposed about the ball nut and have a retaining member that includes a finger for extending into the first groove to engage the ball nut and driven pulley without separate fasteners.