Ball Nut Plain Bearing for Steering Housing Misalignment
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Solution Overview
Problem
The misalignment of individual housings in vehicle power steering assemblies leads to binding and increased friction in the ball nut assembly, and the complexity of rolling bearings increases the cost of the ball nut assembly.
Innovation Solution
A plain bearing structure is introduced, featuring a convex outer bearing surface on the ball nut and a complementary concave inner bearing surface on an insert, which reduces friction and cost by allowing relative sliding movement and is supported by a polymer material, with a retention member to secure the insert in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rolling bearing is used to support the ball nut assembly, then the support function is provided, but the device complexity and cost increase due to multiple components
Solution Approach 1:
The invention extracts only the essential support function from a complete rolling bearing, eliminating unnecessary components like inner and outer races. This leaves only the critical rolling elements that provide the support function, thereby reducing device complexity while maintaining reliability
Solution Approach 2:
The invention uses simple, inexpensive spherical elements instead of complex rolling bearings. These simple elements provide adequate support function at lower cost and complexity, accepting that they may have shorter service life but delivering significant cost savings
2Ease of manufacture
If individual housings are joined together to form the power steering assembly, then the housing structure is created, but misalignment occurs due to casting and machining tolerances
Solution Approach 1:
The invention introduces adjustable positioning features that allow the ball nut assembly to dynamically adapt to misalignment between joined housings. The assembly can shift and adjust its position to compensate for tolerance accumulation, maintaining proper alignment despite variations in housing manufacturing
Solution Approach 2:
The invention employs adjustable parameters in the ball nut assembly positioning system, allowing modification of alignment parameters to compensate for housing misalignment. This enables the system to adapt to varying manufacturing tolerances while maintaining operational precision
3Ease of operation
If misalignment occurs in the ball nut assembly, then binding increases, but friction and internal resistance increase
Solution Approach 1:
The invention makes the ball nut assembly positioning dynamic rather than fixed, allowing it to automatically adjust and maintain optimal alignment during operation. This dynamic adjustment prevents binding and minimizes friction by continuously adapting to operational conditions
Solution Approach 2:
The ball nut assembly incorporates self-aligning features that automatically compensate for misalignment without external intervention. The assembly self-adjusts its position to maintain proper alignment, reducing binding and friction through self-correcting mechanisms
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
This solution reduces binding and costs associated with the ball nut assembly by providing a simpler, friction-reducing support that aligns with the housing design, enhancing the operational efficiency and cost-effectiveness of the power steering system.
Implementation Method 1
The convex outer bearing surface and concave inner bearing surface are configured to provide relative sliding movement between the convex outer bearing surface and the concave inner bearing surface
Data Source
AI summary
A vehicle power steering assembly includes a housing, a ball nut configured to be operatively disposed in the housing and including an extension portion provided with a convex bearing surface, an insert supported on the housing and provided with a concave bearing surface. The concave bearing surface is complementary to the convex bearing surface. The convex and concave bearing surfaces are a plain bearing configured to provide sliding movement relative to each other. The sliding movement provides relative rotation between the convex and concave bearing surfaces in a first direction on the ball nut axis and a second direction on a rotation axis that is transverse to the ball nut axis.