Steering Column Rolling Guide Layout for High Rigidity Adjustment
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Solution Overview
Problem
Existing steering column designs face challenges in achieving high rigidity and compactness while maintaining smooth adjustability and low manufacturing costs, due to the limitations of rolling element guides on side surfaces and tight tolerances required for precise bearing play.
Innovation Solution
The design optimizes the arrangement of rolling element guides in polygonal casing tubes with a specific rolling body radius and enveloping circle configuration, allowing for higher rigidity and a more compact design, along with the use of a method to calibrate the adjustment force by plastic deformation of raceways during assembly, reducing the need for precise dimensional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rolling element guides are placed on the connecting faces of polygonal casing tubes, then smooth and low-backlash adjustability is achieved, but the overall stiffness is limited and installation space requirement increases
Solution Approach 1:
The patent transitions the rolling element guide placement from the 2D connecting faces to the 3D corner regions of the polygonal casing tubes. This spatial relocation allows the rolling elements to engage with raceways formed by adjacent connecting faces meeting at corners, effectively utilizing the third dimension to resolve the conflict between smooth adjustment and structural stiffness.
Solution Approach 2:
The patent employs curved or rounded corner regions in the polygonal casing tubes to form the raceways for rolling elements. This curvature allows the rolling elements to maintain continuous contact with the raceway surfaces during adjustment, ensuring smooth motion while the rounded geometry distributes stresses more effectively than sharp corners, preserving stiffness.
2Strength
If tight tolerances are specified for bearing clearance of rolling elements to raceways, then stiffness is maintained, but manufacturing and assembly costs increase
Solution Approach 1:
The patent incorporates preliminary clearance compensation features directly into the raceway geometry during manufacturing. By pre-building in tolerance compensation through the raceway profile design, the system achieves the necessary bearing clearance control without requiring ultra-tight manufacturing tolerances, thereby reducing manufacturing and assembly costs while maintaining stiffness.
3Length of moving object
If the steering column is compressed to maximum longitudinal adjustment range, then the steering wheel can be stowed outside the operating position, but the adjustment force increases due to insufficient bearing clearance
Solution Approach 1:
The patent optimizes the bearing clearance parameter as a function of the adjustment position. By designing the raceway geometry to maintain appropriate clearance throughout the full adjustment range, the system ensures that even at maximum compression, the bearing clearance remains sufficient to allow smooth movement without excessive adjustment force, while still achieving the desired stowage position.
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 approach enhances the flexural rigidity and compactness of the steering column, reduces manufacturing complexity, and ensures smooth operation with minimal adjustment force, while maintaining high rigidity and low backlash.
Implementation Method 1
rolling elements having a rolling element radius are arranged to roll longitudinally in raceways of a rolling element guide between the sleeve tubes
Implementation Method 2
a method to calibrate the adjustment force by plastic deformation of raceways during assembly
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a steering column (1) for a motor vehicle, comprising a casing unit (3) in which a steering spindle (4) is mounted so as to be rotatable about a longitudinal axis (L) extending in the longitudinal direction and which has at least two steering column tubes (31, 32, 33) guided adjustably relative to each other in the longitudinal direction and having a polygonal cross-section, wherein rolling elements (7, 8) having a rolling element radius (k) are arranged between the steering column tubes (31, 32, 33) in raceways (34, 35, 36, 37) so as to be able to roll in the longitudinal direction, wherein at least three raceways (34, 35, 36, 37) are distributed over the circumference. In order to enable greater rigidity and a compact design, according to the invention the center points (K1, K2) of the rolling elements (7, 8) which can roll radially on the outside of a steering column tube (32, 33) have a radial distance (a, b) smaller than or equal to the rolling element radius (k) from an envelope circle (90, 93) which circumscribes the steering column tube (32, 33) on the outside of which the rolling elements can roll.