Steering Shaft Ball Cage Retention for Variable Ball Diameters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering shafts face challenges in secure assembly and operational reliability due to the risk of damage during ball insertion, particularly with balls of different diameters, leading to either insecure retention or potential deformation of the ball cage.
Innovation Solution
Implementing multiple pairs of resilient retaining tongues that distribute the load and provide a redundant retention mechanism, allowing for secure holding of balls with varying diameters without excessive deformation, and optimizing the arrangement to minimize material stress and ensure easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the opening edge is elastically expanded by the ball during insertion, then the ball can be inserted into the receiving opening, but the opening edge may be overstretched and plastically deformed or damaged
Solution Approach 1:
The continuous opening edge is segmented into multiple retaining tongues (at least two, preferably three or more) distributed around the circumference of the receiving opening. Each retaining tongue independently bears the expansion force during ball insertion, preventing any single point from being overstretched and damaged while still allowing elastic expansion for easy ball insertion.
Solution Approach 2:
The retaining tongues are designed with specific local properties: they are resilient to allow elastic expansion during insertion, have a free end that protrudes into the receiving opening to provide form-fit retention, and are distributed circumferentially to locally distribute stresses. This local quality optimization resolves the contradiction between ease of insertion and edge strength.
2Adaptability or versatility
If balls with different diameters are used, then adaptability to different designs and tolerance compensation is achieved, but balls with small diameters are not securely held while balls with large diameters cause sluggish movement and damage risk
Solution Approach 1:
The retaining tongue design serves multiple functions simultaneously: it provides elastic expansion for easy insertion, forms a resilient form-fit retention mechanism that adapts to different ball diameters, and distributes loads circumferentially. The free end of each retaining tongue protrudes into the receiving opening to engage with balls of varying diameters, ensuring secure retention across the full range of ball sizes while maintaining reliability.
Solution Approach 2:
The resilient retaining tongues can change their engagement parameters (position, deformation degree) to adapt to balls of different diameters. When a ball is inserted, the retaining tongues elastically deform to accommodate the ball diameter, then spring back to provide form-fit retention. This parameter change capability allows the same ball cage design to securely hold balls across a range of diameters without compromising reliability.
3Device complexity
If a single retaining tongue is used per receiving opening, then the structure is simple, but the load on the single retaining tongue is high increasing damage risk
Solution Approach 1:
The retention function is segmented into multiple retaining tongues (at least two, preferably three or more) distributed around the circumference of the receiving opening. This segmentation divides the total load that would fall on a single retaining tongue into multiple smaller loads, reducing the stress and damage risk on each individual retaining tongue while maintaining structural simplicity through the modular distributed arrangement.
4Reliability
If the entry diameter of the opening edge is made smaller than the ball diameter for secure retention, then balls are held securely, but the opening edge must be elastically expanded which increases the risk of plastic deformation
Solution Approach 1:
The retaining tongues are designed to be resilient and dynamic rather than static. During ball insertion, the retaining tongues elastically deform (change shape) to allow the ball to pass through the opening edge. Once the ball is in position, the retaining tongues spring back to their original shape, creating a dynamic form-fit retention mechanism. This dynamic behavior resolves the contradiction by allowing easy insertion through elastic deformation while maintaining secure retention through the spring-back effect.
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 solution enhances assembly simplicity, reduces the risk of damage, and improves operational reliability by securely holding balls of all diameters without deforming the ball cage, even when inserting the largest balls, while maintaining a loose form-fit to prevent damage.
Implementation Method 1
The at least one retaining tongue, which extends over a partial peripheral area of the receiving opening, protruding from the edge of the opening, is resilient
Implementation Method 2
at least one, usually several, balls are arranged as rolling bodies in the generic design, which can roll between the outer surface of the inner shaft and the inner surface of the hollow shaft in the direction of the longitudinal axis
Implementation Method 3
The balls are held in position and guided between the shafts and at a distance relative to one another by being accommodated in a ball cage
Data Source
Figure 1~4
Figure 5~8
AI summary
The invention relates to a steering shaft (1) for a motor vehicle, comprising a hollow shaft (20) and an inner shaft (30) which is arranged in the hollow shaft (20) in a coaxial manner, is telescopable relative to the hollow shaft (20) in the direction of the longitudinal axis (L) of the steering shaft (10), and is connected to the hollow shaft (20) via at least one ball (40) so as to transmit a torque, wherein a ball cage (50) is arranged coaxially between the inner shaft (30) and the hollow shaft (20), said ball cage having at least one radial receiving opening (51) in which a ball (40) is received in a freely rotatable manner and which has a circumferential opening edge. The aim of the invention is to allow an improved mounting of balls with different ball diameters. According to the invention this is achieved in that at least one holding tongue (6a, 6b, 6c, 6d, 6e, 6f) which extends over a circumferential subregion of the receiving opening (51) protrudes from the opening edge.