Parylene-Coated Ball Joint Bearing Shell for Low-Friction Sliding
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Solution Overview
Problem
Existing ball joints in vehicle chassis experience undesired friction effects such as breakaway and stick-slip due to mixed and solid-body friction, necessitating a reduction in the coefficient of friction between the joint ball and bearing shell.
Innovation Solution
A bearing shell with a parylene low-friction layer applied via chemical gas-phase deposition, preferably made of fluorinated parylene, is integrated into the shell component to reduce friction, which can be as thin as 1 μm and uniformly coated on the inside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional bearing shell material is used, then the shell has sufficient strength and pressure resistance, but the friction coefficient between the joint ball and bearing shell is too high causing breakaway and stick-slip effects
Solution Approach 1:
The bearing shell is constructed as a composite structure with an inner parylene coating layer and an outer shell material layer. The parylene layer provides low-friction properties while the outer shell material ensures structural strength and pressure resistance, combining the benefits of both materials in a single component.
Solution Approach 2:
The invention changes the surface properties of the bearing shell by applying a parylene coating, which fundamentally alters the friction characteristics from high-friction traditional materials to low-friction parylene surface, while maintaining the bulk mechanical properties through the outer shell layer.
2Object-generated harmful factors
If a thick low-friction layer is applied to reduce friction, then the sliding properties improve, but the structural integrity and pressure resistance of the shell deteriorate
Solution Approach 1:
The composite structure allows a thin parylene layer to provide friction reduction without compromising structural integrity, as the load-bearing function is maintained by the outer shell material layer while the inner parylene layer provides surface-level friction reduction.
Solution Approach 2:
The parylene coating is applied only to the inner surface of the bearing shell where friction occurs, rather than making the entire shell thick. This localized application provides friction reduction exactly where needed while maintaining overall structural strength through the outer shell layer.
3Strength
If a thin parylene layer is used, then the friction reduction is effective and structural integrity is maintained, but the coating may not be sufficiently durable under high pressure
Solution Approach 1:
The composite structure with inner parylene and outer shell material layers works synergistically, where the parylene provides friction reduction and the outer shell provides structural support and pressure distribution, protecting the thin parylene layer from direct high-pressure damage while maintaining coating durability.
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 parylene layer significantly reduces friction between the bearing shell and joint ball, enhancing sliding properties while maintaining structural integrity and resistance to pressure.
Implementation Method 1
The parylene low-friction layer is applied onto the inside surface of the shell component by means of a chemical gas-phase deposition
Implementation Method 2
the second material is or contains zinc. Likewise, it is known therefrom that a lubricant is used in the ball joint to reduce the friction between the joint ball and the bearing shell
Data Source
AI summary
A bearing shell (2) for a ball joint (1) includes a shell component (11) made from a first material, such that the shell component (11) has a ball segment shaped receiving space (6) into which a joint ball (4) is fitted and can swivel. An inner side (12) of the shell component (11) is coated with a second material to form a low-friction layer (13). To improve the sliding friction properties between the joint ball (4) and the bearing shell (2) and to reduce the friction between them, the bearing shell (2) is characterized in that the second material is parylene.