Pneumatic Spring Rolling Bellows with Variable Reinforcement
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Solution Overview
Problem
Existing air spring rolling bellows face challenges in balancing stress distribution across different loaded areas, leading to either oversized designs for low-load areas or potential failure when optimized for high-load areas, with complex manufacturing processes.
Innovation Solution
The rolling bellows is designed with two tubular parts of different diameters, featuring varying thread angles and reinforcement densities, connected via a simple clamp connection, allowing for balanced stress distribution and easy production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rolling bellows is designed for high-load areas with high reinforcement density, then load-carrying capacity is improved, but low-load areas become oversized and uneconomical
Solution Approach 1:
The rolling bellows is divided into multiple zones along its length, each with different reinforcement densities and thread angles. The first zone (near the piston) has higher reinforcement density with thread angles of 45-60 degrees to handle high dynamic loads from rolling. The second zone (middle section) has medium reinforcement density with thread angles of 30-45 degrees. The third zone (near the cover) has lower reinforcement density with thread angles of 15-30 degrees for primarily static load bearing. This localized differentiation optimizes material usage while maintaining strength where needed.
Solution Approach 2:
The rolling bellows is segmented into distinct zones with different structural characteristics. Each zone can be independently optimized for its specific loading conditions. The segmentation allows the bellows to efficiently distribute materials to areas of high stress while reducing material in areas of low stress, thereby improving overall structural efficiency and reducing unnecessary material consumption.
2Ease of manufacture
If the rolling bellows is designed with uniform reinforcement density, then manufacturing is simplified, but the structure cannot adapt to different load conditions in different areas
Solution Approach 1:
Different zones of the rolling bellows are equipped with reinforcements at different angular positions and densities. The first zone has reinforcements at 45-60 degrees to the axis, the second zone at 30-45 degrees, and the third zone at 15-30 degrees. This local differentiation enables each zone to adapt to its specific loading conditions while maintaining a systematic manufacturing approach that is more simple than fully custom fabrication.
3Strength
If the rolling bellows wall thickness is increased, then strength is improved, but the design becomes oversized for low-load areas
Solution Approach 1:
The wall thickness and reinforcement density are varied locally across different zones of the rolling bellows. The first zone near the piston has greater wall thickness and higher reinforcement density to withstand high dynamic loads. The third zone near the cover has reduced wall thickness and lower reinforcement density since it primarily bears static loads. This localized optimization ensures structural strength where needed while avoiding oversizing in low-load areas, improving dimensional efficiency.
4Reliability
If the rolling bellows is optimized for dynamic loads in the rolling fold area, then reliability is improved, but other areas become uneconomical
Solution Approach 1:
The rolling bellows is designed with zone-specific reinforcement characteristics that match the actual stress distribution during operation. The first zone near the rolling fold area has high reinforcement density with thread angles of 45-60 degrees to reliably handle high dynamic loads and extend service life. The third zone near the cover has lower reinforcement density with thread angles of 15-30 degrees, as it primarily experiences static internal pressure. This localized optimization improves reliability in critical areas while avoiding unnecessary material usage in less critical areas.
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 design achieves a balanced state of stress across different loaded areas, enhancing load-carrying capacity and service life while simplifying manufacturing and reducing costs.
Implementation Method 1
a rolling bellows for an air spring of a passenger car usually consists of elastomer materials... when filled with compressed air, forms a rolling fold adjacent to a connecting part and an air spring chamber adjoining it
Implementation Method 2
The reinforcements are aligned in their layers at an angle, namely at the so-called thread angle to the axis or to the axis normal of the cylindrical body. In this case, the reinforcements in adjacent layers are often arranged crossed with respect to one another
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The air spring rolling bellows (1) are fixed between two connectors and are formed under filling with compressed air of a rolling fold (6) and an air spring chamber (7). The rolling bellows are made of two tube-shaped rolling bellows pieces (1a,1b) connected to each other and the rolling bellows pieces have different diameters (2,3).