Joint Bellows Pleat Structure for Cold-Start Stick-Slip Reduction
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Solution Overview
Problem
Bellows used in joint arrangements face issues such as wear and stress due to flank contact, friction, and load, as well as noise generation due to the 'stick-slip effect, especially under cold start conditions where the lubricant hinders the movement of pleats, leading to potential failure.
Innovation Solution
The bellows design incorporates pleats with elevations and depressions along the circumferential direction, which are elastically deformable, reducing adhesion by displacing lubricant and generating forces that facilitate the separation of pleats, thereby reducing stress and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flat surfaces are used for pleat flanks, then sealing is improved, but adhesion increases causing stick-slip effect and noise
Solution Approach 1:
The invention applies local quality by creating structures with different properties at different locations on the pleat flanks. The elevated or depressed areas (local regions) have different contact characteristics compared to the surrounding flat surfaces, allowing the bellows to maintain sealing while reducing adhesion in specific critical zones where stick-slip occurs.
Solution Approach 2:
The invention segments the continuous flat contact surface of the pleat flanks into multiple smaller contact zones separated by elevated or depressed areas. This segmentation reduces the total area of adhesive contact between opposing flanks, thereby reducing the stick-slip effect and associated noise while preserving sealing functionality.
2Force
If lubricant is applied inside the bellows, then friction is reduced, but adhesion increases under cold start conditions
Solution Approach 1:
The invention changes the physical parameters of the pleat flank surfaces by adding elevated or depressed areas, which modifies how lubricant interacts with the surfaces. This geometric modification reduces the effective contact area where lubricant-induced adhesion occurs, particularly under cold start conditions, while still allowing lubricant to reduce friction in non-contact zones.
3Force
If large contact surfaces are used between opposing flanks, then load capacity is improved, but adhesive effect increases
Solution Approach 1:
The invention segments the large continuous contact surface into multiple smaller contact zones separated by elevated or depressed areas. This segmentation reduces the total adhesive contact area while distributing the load across multiple discrete contact points, thereby maintaining load capacity while reducing the overall adhesive effect between opposing flanks.
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 modified pleat design enhances the bellows' ability to withstand cold start conditions by reducing adhesion and stress, ensuring smooth operation and extending its lifespan by minimizing the risk of failure.
Implementation Method 1
each structure being formed by an elevation enlarging the inner space 8 or by a depression reducing the inner space 8. The pleats 9, 10 and structures 16 are designed or configured in such a way that when the pleats 9, 10 are in contact with one another, the structures 16 are elastically deformable, thereby increasing a contact surface, present in the inner space 8, between the flanks 12, 14 of the pleats 9, 10
Implementation Method 2
the lubricant regularly arranged inside the bellows appears to hinder a pre-determined movement of the pleats (i.e. the opening and positioning of the pleats against each other resulting from a rotation of ends of the bellows that are not arranged coaxially to each other). For example, the opening of the pleats is hindered by an adhesive effect of the lubricant in contact with the pleats
Implementation Method 3
Bellows are subject to the following signs of wear and stress for example when used as intended: 1. fatigue due to flank contact (of the walls of the pleats), friction and load
Data Source
AI summary
A bellows for a joint arrangement extends between a first end and a second end as a hollow body along an axis and is formed by a wall which encloses the axis between the ends along a circumferential direction and forms an inner space; wherein the wall is formed at least by a plurality of pleats arranged side by side along the axis; wherein each pleat extends along the axis starting from a first smallest diameter via a first flank to a first largest diameter and via a second flank to a second smallest diameter and a flank of at least one pleat has a plurality of structures arranged distributed along the circumferential direction.