Plastic Rolling Piston Structure for Air Spring Stress Relief
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Solution Overview
Problem
Conventional rolling pistons for air springs in motor vehicles experience local stress peaks during operation, particularly at the edge region where inner ribs meet the outer circumference, leading to potential damage over time.
Innovation Solution
A rolling piston design featuring a recessed end face on the core, Y-shaped inner ribs, and a S-shaped inner diameter reduction in the intermediate wall to distribute pressure and reduce stress, manufactured using injection molding for cost-effectiveness and airtightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the core end face is solid without recess, then manufacturing is simpler, but local stress peaks occur at the edge area where inner ribs meet the outer circumference
Solution Approach 1:
The recess is introduced specifically at the critical edge area where inner ribs meet the outer circumference of the end face. This localized modification allows the rest of the core to remain solid and simple to manufacture, while only the problematic region is altered to reduce stress concentration. The recess creates a stress-relief geometry that prevents crack initiation at the high-stress zone without complicating the overall manufacturing process.
Solution Approach 2:
The recess acts as a pre-designed stress-relief feature that cushions the impact of internal pressure forces before they can concentrate at the vulnerable edge area. By providing this geometric cushioning in advance, the design prevents the formation of critical stress states that would otherwise lead to damage over time during operation.
2Ease of manufacture
If the rolling piston structure is simplified, then manufacturing cost decreases, but structural rigidity and stress distribution are compromised
Solution Approach 1:
The recess modifies the geometric parameters of the core end face, creating a controlled void that changes the stress distribution pattern. This parameter change allows the structure to maintain adequate rigidity while better distributing internal pressure forces, avoiding the need for more complex reinforcing structures that would increase manufacturing cost.
Data Source
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AI summary
The invention relates to a rolling piston (6) for a pneumatic spring (4) of a motor vehicle, said rolling piston (6) being made of plastic. The outer lateral surface (12) of an annular outer wall (13) of the rolling piston (6) is suitable for functioning as a stop surface for a rolling bellows (7) of the pneumatic spring (4) when the rolling piston (6) is installed. A core (14) which is enclosed by the outer wall (13) and at the same time is concentric to the outer wall (13) extends from the base side (9) of the rolling piston (6) in the direction of a central axis (11) of the rolling piston (6), and inner ribs (15) extend away from the core (14) at least substantially in a radial direction. The invention is characterized in that the core (14) has an end region (16) which is arranged at a distance from the base side (9) of the rolling piston (6) and has an end face (17) facing away from the base side (9) of the rolling piston (6), and a recess (18) which extends in the direction of the base side (9) and at the same time is closed on the base side is formed on the end face (17). The invention additionally relates to a pneumatic spring (4) comprising such a rolling piston (6).