Concentric Bushing Assembly for Lash-Free Steering Mounts
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Solution Overview
Problem
Concentric bushing assemblies in steering systems face challenges in providing a cost-effective and performance-efficient solution for mounting geometries, particularly in column electric power steering systems, where high mount geometries use a single sleeve while concentric mount geometries require two separate mounts, leading to clearance issues and varying bushing material performance.
Innovation Solution
A concentric bushing assembly is designed with a bushing and insert configuration, where the bushing has a cylindrical body and flanged end with specific outer diameters, and an insert with its own cylindrical and flanged ends, providing a press fit and compliance for stable pivoting and load assistance, using plastic and metal materials respectively, and allowing for secure assembly without additional caps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two separate lower mounts are used for concentric mount geometry, then clearance for output shaft and intermediate shaft yolk is provided, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines two separate lower mounting bushings into a single integrated concentric bushing assembly. The outer bushing provides mounting functionality while the inner bushing provides clearance for the output shaft and intermediate shaft yolk. This merging eliminates the need for two separate mounting components, reducing device complexity and manufacturing cost while maintaining the required clearance functionality.
Solution Approach 2:
The patent implements a nested structure where an inner bushing is positioned within an outer bushing. The inner bushing has a smaller diameter and provides clearance for rotating components, while the outer bushing provides the mounting interface. This nesting arrangement allows both bushings to work together in a single integrated assembly, solving the clearance requirement without increasing the number of separate mounting components.
2Ease of manufacture
If rubber or plastic bushings are used, then cost is reduced, but performance and load-bearing capability deteriorate
Solution Approach 1:
The patent employs a composite bushing structure where the outer bushing is made of rubber or plastic material for cost-effectiveness and damping properties, while the inner bushing is made of metal material for superior load-bearing capability and structural integrity. This composite approach allows the assembly to benefit from both material types - the cost and damping advantages of rubber/plastic and the strength and reliability of metal - thereby resolving the contradiction between manufacturing cost and performance.
3Reliability
If additional caps are used to secure bushings, then assembly reliability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent designs the concentric bushing assembly to be self-retaining without requiring additional caps or external securing components. The nested structure of the inner and outer bushings, combined with their specific dimensional relationships and material properties, creates a self-locking mechanism that secures the assembly in place. The inner metal bushing's rigidity and the outer rubber/plastic bushing's elasticity work together to maintain the assembly's integrity under load, eliminating the need for additional securing components and reducing device complexity.
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 bushing assembly achieves a lash-free, noise-free fit that can handle assist loads and road inputs, providing a cost-effective and performance-efficient solution for concentric mount geometries by ensuring a tight, compliant interface and secure assembly, even on non-machined surfaces.
Implementation Method 1
an insert having an insert cylindrical body extending to a third outer diameter and an insert flanged end extending to a fourth outer diameter that is larger than the third outer diameter, the cylindrical body disposed within the bushing cylindrical body
Data Source
AI summary
A concentric bushing assembly is provided. The assembly includes a bushing having a bushing cylindrical body extending to a first outer diameter and a bushing flanged end extending to a second outer diameter that is larger than the first outer diameter. The assembly also includes an insert having an insert cylindrical body extending to a third outer diameter and an insert flanged end extending to a fourth outer diameter that is larger than the third outer diameter, the cylindrical body disposed within the bushing cylindrical body.