Steering Column Bracket Welding to Prevent Interference Fit Deformation
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Solution Overview
Problem
The conventional steering column design faces challenges in maintaining appropriate axial sliding resistance between the inner and outer columns, leading to variations in interference fit and increased manufacturing costs due to residual stress-induced deformation during welding.
Innovation Solution
The steering column design incorporates a tubular outer column with a press-fitted inner column, where the column-side bracket is welded at two locations close in the circumferential direction, reducing deformation and maintaining appropriate sliding resistance through a controlled interference fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the column-side bracket is welded to the outer column at locations separated in the circumferential direction, then the bracket is securely fixed to the outer column, but residual stress-induced deformation occurs in the press-fitted portion, causing variation in interference fit and making it difficult to maintain appropriate axial sliding resistance
Solution Approach 1:
The patent applies local quality by positioning the weld locations specifically in non press-fitted portions of the outer column, where welding will not affect the interference fit quality. This localized placement strategy allows secure bracket fixation while preserving the precision of the press-fitted portion, directly resolving the contradiction between fixation strength and manufacturing precision.
2Strength
If the column-side bracket is welded to the outer column, then the bracket is securely fixed, but residual stress causes deformation of the press-fitted portion requiring selective combination of inner and outer columns
Solution Approach 1:
By restricting welding to non press-fitted portions of the outer column, the patent eliminates residual stress-induced deformation in the press-fitted area. This removes the need for selective combination of inner and outer columns, thereby simplifying the assembly process while maintaining secure bracket fixation.
3Stability of the object's composition
If the inner column and outer column have high sliding resistance, then the steering column is stable during normal operation, but impact load absorption during secondary collision is reduced
Solution Approach 1:
The patent optimizes the interference fit parameters between the inner and outer columns to achieve an appropriate balance. By carefully controlling the press-fit dimensions and material properties, the design maintains sufficient sliding resistance for normal operational stability while preserving adequate impact load absorption capability during secondary collisions.
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 configuration simplifies the maintenance of appropriate axial sliding resistance, reduces manufacturing costs by minimizing the need for precise alignment, and stabilizes impact load absorption during secondary collisions.
Implementation Method 1
the impact load during the secondary collision is absorbed due to the outer-circumferential surface of the inner column 9 and the inner-circumferential surface of the outer column 10 sliding in the axial direction
Implementation Method 2
The inner-circumferential surface of the press-fitted portion and the outer-circumferential surface of the inner column come in contact with each other with an interference fit
Implementation Method 3
At least one location of the column-side bracket is welded to the outer-circumferential surface of the press-fitted portion at only two weld locations that are close in the circumferential direction
Data Source
AI summary
The outer column 25 has a front-side small-diameter tubular portion 37 into which the inner column 24 is press fitted. The inner-circumferential surface of the front-side small-diameter tubular portion 37 and the outer-circumferential surface of the inner column 24 come in contact with an interference fit at only a plurality of contact locations separated in the circumferential direction. At least one location in the axial direction of the column-side bracket 26 is welded to the outer-circumferential surface of the front-side small-diameter tubular portion 37 at only two weld locations that are close in the circumferential direction.