Telescopic Steering Shaft With Sacrificial Load-Absorbing Section
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Solution Overview
Problem
In steering apparatuses, impactive moment loads during accidents or curb riding can cause tie rods to deform, leading to improper wheel alignment.
Innovation Solution
A telescopic shaft with a hollow outer tube and inner shaft, featuring a male spline portion and female spline portion for torque transmission, includes a small-diameter portion with a cylindrical surface and continuous curved surfaces to absorb moment loads, preventing deformation of other components and maintaining proper wheel alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a telescopic structure is applied to the intermediate shaft to reduce total length and absorb vibrations, then the shaft can be assembled with reduced length and vibrations are absorbed, but the structure becomes more complex and may deform under impactive moment loads
Solution Approach 1:
The intermediate shaft is divided into multiple segments: an outer shaft and an inner shaft that can telescopically extend and contract. This segmentation allows the shaft to change its total length while maintaining a manageable structural complexity through modular design
Solution Approach 2:
A small-diameter portion is specifically provided in the inner shaft at a location different from the spline engagement portion. This local variation in diameter creates a designated deformation zone that absorbs impactive moment loads, protecting other components while maintaining overall structural integrity
2Reliability
If the intermediate shaft uses a telescopic structure to absorb vibrations and reduce length, then assembly is simplified and vibrations are reduced, but the shaft may deform under collision loads causing improper wheel alignment
Solution Approach 1:
The small-diameter portion in the inner shaft is designed in advance as a sacrificial element that will deform first under impactive moment loads. This beforehand cushioning protects the spline engagement portions and other critical components from deformation, ensuring wheel alignment is maintained
Solution Approach 2:
By providing a localized small-diameter portion with reduced strength characteristics at a specific location in the inner shaft, the design creates a controlled weak point that absorbs impact energy through deformation, thereby protecting the overall structural integrity and reliability of the steering system
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 telescopic shaft effectively absorbs moment loads, preventing improper wheel alignment by deforming the small-diameter portion before other components, thus maintaining the integrity of the steering apparatus.
Implementation Method 1
the small-diameter portion...to absorb moment loads, preventing deformation of other components and maintaining proper wheel alignment
Implementation Method 2
The inner shaft and the outer tube are combined with each other by a spline engagement between the male spline portion and the female spline portion such that torque can be transmitted
Data Source
AI summary
A structure capable of preventing improper wheel alignment even when, for example, an accident such as a collision accident, steered wheels riding on a curb, or the like occurs is realized. A telescopic shaft in which the inner shaft (9a) and the outer tube (10a) are combined with each other by a spline engagement between the male spline portion (45) provided on one end portion in the axial direction of the outer-circumferential surface of the inner shaft (9a) and the female spline portion (23) provided on the other end portion of the inner-circumferential surface of the outer tube (10a) such that torque can be transmitted and the entire length of the telescopic shaft can be extended and contracted, the inner shaft (9a) having an inner-side small-diameter cylindrical portion (41) provided on a portion of the inner shaft (9a) that is located further on the other side than the edge of the other end in the axial direction of the outer tube (10a) and having an outer-diameter dimension that is smaller than the adjacent portions on both sides in the axial direction thereof, is provided.