Ball Joint Protective Cap With Fine Thread Self-Locking
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Solution Overview
Problem
Existing protective caps for ball joints lack precise and repeatable positioning due to elastic tongues that do not ensure exact alignment with the ball pivot's thread, leading to tilting and inconsistent sealing pressure, which affects the securement of the sealing bellows and increases the risk of mechanical damage.
Innovation Solution
A protective cap with a multiple circumferential internal thread that matches the external thread of the ball pivot, providing a self-locking mechanism for precise and repeatable positioning, combined with a non-flexible design and additional features like rib structures for rigidity and sealing surfaces for enhanced protection and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an elastic tongue is used to engage with the external thread, then the protective cap can be easily installed, but the positioning precision and repeatability are compromised
Solution Approach 1:
The patent changes the engagement mechanism from an elastic tongue to a threaded connection with a specific pitch. The thread pitch is designed to be finer than standard threads, which increases the self-locking effect and reduces the axial movement per rotation, thereby improving positioning precision while maintaining ease of installation through the threaded engagement mechanism.
2Ease of manufacture
If a standard thread pitch is used, then the protective cap can be manufactured simply, but the positioning repeatability and self-locking effect are insufficient
Solution Approach 1:
The patent employs a fine thread pitch that is smaller than standard thread pitches. This parameter change enhances the self-locking effect of the thread connection, preventing the protective cap from detaching or tilting after installation. The finer pitch also reduces the axial displacement per rotation, improving positioning repeatability while remaining manufacturable using standard threading processes.
3Ease of operation
If the protective cap tilts during installation, then the elastic tongue can accommodate misalignment, but the sealing pressure becomes inconsistent
Solution Approach 1:
The threaded connection with fine pitch provides a self-locking effect that prevents tilting of the protective cap during and after installation. The friction generated by the fine thread engagement counteracts any tilting forces, ensuring that the protective cap remains axially aligned with the ball pivot, thereby maintaining consistent sealing pressure at the contact surface.
4Adaptability or versatility
If the elastic tongue is pulled back into a thread, then the protective cap can be repositioned, but the positioning stability is compromised
Solution Approach 1:
The fine thread pitch creates a strong self-locking effect through increased friction, which prevents the elastic tongue from being accidentally pulled back into a thread. The threaded connection geometry ensures that once the protective cap is screwed onto the ball pivot, it remains securely in position without unintended movement, thereby maintaining positioning stability while still allowing deliberate repositioning by unscrewing.
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
Ensures exact and repeatable positioning of the protective cap on the ball pivot, maintaining consistent sealing pressure and reducing the risk of mechanical damage, while allowing for easy installation and removal without specialized tools.
Implementation Method 1
The internal thread is preferably designed as a fine thread, in particular as a metric ISO fine thread according to DIN 13. For example, a fine thread with an outer diameter of 24 millimeters and a thread pitch from one thread to the next following thread of 1.5 millimeters can be used. Fine threads have the advantage that they have a self-locking effect due to their low pitch compared to standard threads, which prevents the protective cap from detaching itself from the threaded pin.
Implementation Method 2
An inner peripheral surface of the front end of the sealing bellows is pressed against the ball pivot in the region of a contact surface between the conical section of the ball pivot and the aforementioned inner peripheral surface.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Disclosed is a protective cap (1, 30) for covering some sections of a ball-joint (50) mounting assembly, the protective cap (1, 30) being characterised in that it can be screwed onto a threaded section (53) of a ball journal (51) of the ball joint (50) by means of an inner thread (11) with multiple revolutions. Also disclosed is a ball joint (50) comprising a ball journal (51), in which said protective cap (1, 30) is screwed onto a threaded section (53) of the ball journal (51). The invention further relates to a two-point linkage (80) comprising at least one ball joint (81, 82) of the aforementioned type, characterised in that the two-point linkage is designed as a drag link (80), tie rod, stabiliser connecting rod, control linkage, or Panhard rod.