Steering Outer Tube Structure to Block Moisture Ingress
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Solution Overview
Problem
The existing outer tubes of intermediate shafts in steering apparatuses are prone to foreign matter ingress, such as moisture, which hinders smooth operation and increases manufacturing costs due to the need for welding and subsequent processing to secure the joint, affecting the effective length and phase accuracy of the shaft.
Innovation Solution
An outer tube with a hole cover configuration, where a cold-forged solid male-shaft portion is integrated with a bottomed cylindrical female-tube portion, and a hole cover is externally fitted to prevent foreign matter ingress, eliminating the need for welding and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer tube is configured as an overall hollow tubular shape with a male-shaft portion and female-tube portion, then workability and weight are improved, but foreign matter such as moisture can enter inside the female-tube portion and hinder smooth extending/contraction operation
Solution Approach 1:
The outer tube is divided into a male-shaft portion with a solid cross-section and a female-tube portion with a hollow cross-section. This segmentation allows the male-shaft portion to act as a barrier preventing foreign matter from entering the female-tube portion, while maintaining the hollow structure for weight reduction and workability in other areas.
Solution Approach 2:
The male-shaft portion serves as an intermediary element between the external environment and the internal space of the female-tube portion. By positioning the solid male-shaft portion at the end of the hollow female-tube portion, it mediates to block foreign matter ingress while allowing the hollow structure to maintain its functional benefits.
2Strength
If the male-shaft portion and female-tube portion are connected by welding, then joint strength is improved, but manufacturing cost increases due to additional welding process and subsequent cutting process for removing weld bead
Solution Approach 1:
The male-shaft portion and female-tube portion are designed to be integrally formed as a single piece, eliminating the need for separate joining processes such as welding. This merging of components maintains joint strength while significantly reducing manufacturing cost by removing the welding and subsequent cutting processes.
Solution Approach 2:
The integral structure serves multiple functions simultaneously: it provides joint strength through the continuous material structure, eliminates the need for additional joining processes, and removes the requirement for post-welding cutting operations. This multi-functionality resolves the contradiction between strength and ease of manufacture.
3Reliability
If welding is used to connect male-shaft portion and female-tube portion, then joint reliability is improved, but effective length of inner-peripheral-side engaging portion and phase accuracy become difficult to secure
Solution Approach 1:
By integrating the male-shaft portion and female-tube portion into a single monolithic component, the invention eliminates the joint interface that would otherwise require welding. This ensures precise control over the effective length of the inner-peripheral-side engaging portion and maintains phase accuracy without the complications introduced by welding and subsequent cutting processes.
Solution Approach 2:
The effective length and phase relationship between the male-shaft portion and female-tube portion are determined during the integral forming process itself, rather than being established through subsequent welding and cutting operations. This preliminary determination of critical dimensions ensures manufacturing precision is maintained while achieving joint reliability.
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 effectively prevents foreign matter from entering the inner tube, reduces manufacturing costs, and maintains the strength and extension/contraction functionality of the intermediate shaft while ensuring phase accuracy and effective length.
Implementation Method 1
the outer tube with hole cover according to one aspect of the present invention, in an assembled state in a vehicle body, is such that the male-shaft portion is arranged in the vehicle cabin exterior and an opening portion of the slide hole is arranged in the vehicle cabin interior.
Data Source
AI summary
Provided is an outer tube including a solid-shaped male-shaft portion and a bottomed cylindrical female-tube portion integrally formed with the male shaft portion. A hole cover is externally fitted to the female-tube portion and closes a gap between a dash panel separating the vehicle cabin interior and the vehicle cabin exterior of a vehicle body and the outer tube. In an assembled state in the vehicle body, the solid male-shaft portion is arranged in the vehicle cabin exterior, and an opening portion of a slide hole provided in the female-tube portion is arranged in the vehicle cabin interior.