Telescopic Steering Shaft Pull-Out Stops With Oblique Forming
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Solution Overview
Problem
The existing steering shaft production methods are complicated and costly, often resulting in deformation of the outer shaft part, which impairs the operational reliability due to the need for caulking and forming processes that apply significant forces in the radial direction.
Innovation Solution
The outer stops are introduced into the end face or circumference of the outer shaft part using a forming process with the axis of insertion lying in a plane including the axis of rotation, reducing the radial component of the forming force and minimizing deformation, allowing for easier and more reliable production of the pull-out protection mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If outer stops are introduced by a forming process with the insertion direction forming an angle of more than 20° with the radial direction, then the radial component of the forming force is reduced and deformation of the outer shaft part is minimized, but the forming process becomes more complex compared to direct radial forming
Solution Approach 1:
The forming process transitions from direct radial insertion to oblique insertion at an angle of more than 20° relative to the radial direction. This dimensional change in the insertion angle redirects the forming force to have a smaller radial component, thereby reducing deformation of the outer shaft part while maintaining the forming process for outer stops
2Reliability
If caulking and forming processes are applied to produce outer stops, then pull-out protection is achieved, but significant radial forces cause deformation and reduce operational reliability
Solution Approach 1:
The insertion direction of the forming tool is changed from purely radial to oblique, forming an angle of more than 20° with the radial direction. This redirects the forming force vector to have a larger axial component and a reduced radial component, minimizing deformation of the outer shaft part while still achieving the necessary pull-out protection through outer stop formation
3Ease of operation
If the inner shaft part is pulled out of the outer shaft part, then axial displacement occurs, but without outer stops the inner shaft part can be completely removed
Solution Approach 1:
Outer stops are formed in the outer shaft part to act as intermediary elements that interact with the inner shaft part during axial displacement. These stops serve as mechanical limits that prevent complete removal of the inner shaft part while still allowing controlled telescopic movement, thus providing pull-out protection without compromising the ease of axial displacement
Data Source
Figure 1~3
Figure 4~9
Figure 10~13
AI summary
In order to improve a steering shaft (1) for a motor vehicle, having an outer shaft part (2), in which an inner shaft part (3) is accommodated in a torque-locking and axially displaceable manner, having at least one axial inner stop (17, 18) which projects radially outwards from the outer side (16) of the inner shaft part (3) and, when the inner shaft part (3) is pulled out of the outer shaft part (2), strikes against at least one axial outer stop (20 to 27, 43, 44), which projects radially inwards from the inner side (19) of the outer shaft part (2), such that the axial displacement path of the inner shaft part (3) in the outer shaft part (2) is limited in the pull-out direction (28), in respect of simple production of the outer stops (20 to 27, 43, 44) with the least possible deformation of the entire cross section of the outer shaft part (2), it is proposed that the at least one outer stop (20 to 27, 43, 44) is introduced by at least one forming process in an end portion (29) of the outer shaft part (2), wherein the axis of the introduction direction (30) in each case forms an angle (32) of more than 20° with the radial direction (31) of the outer shaft part (20 to 27, 43, 44).