Plastic Rolling Piston for Commercial Vehicle Air Spring
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Solution Overview
Problem
Existing air spring damper modules with metal pistons are heavy and require galvanic coating for corrosion protection, while plastic piston solutions used in passenger cars lack internal stop buffer support and are not suitable for commercial vehicles due to space constraints.
Innovation Solution
A plastic rolling piston is designed as two parts: a jacket area with a bottom zone and a support area, where the support tube grips the tank pipe and the bottom zone is supported on a shoulder of the support ring, allowing separate distribution of spring and buffer loads, reducing material stress and weight, and eliminating the need for additional corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal rolling piston is used, then high stability and strength are achieved, but weight increases and corrosion protection is required
Solution Approach 1:
The patent replaces the durable metal piston with a plastic piston that is lighter in weight. While plastic has lower strength than metal, the design compensates through structural optimization (two-part construction with support tube and bellows seat) to achieve sufficient load-bearing capacity for commercial vehicle applications.
2Weight of moving object
If a plastic rolling piston is used, then weight is reduced and corrosion protection is eliminated, but internal stop buffer support cannot be provided
Solution Approach 1:
The plastic rolling piston is divided into two separate parts: a support tube portion and a bellows seat portion. This segmentation allows the support tube to extend downward and provide structural support for the stop buffer assembly, while the bellows seat maintains the air spring function. The separation enables independent optimization of each component's function.
Solution Approach 2:
The support tube extends vertically downward from the bellows seat in a third dimension, creating space below the piston to accommodate the stop buffer assembly. This vertical extension allows the plastic piston to provide both air spring support and mechanical stop buffer support, overcoming the space constraints that prevented buffer integration in single-piece plastic piston designs.
3Ease of manufacture
If a single-piece plastic piston is used, then manufacturing is simplified, but stress distribution is poor leading to high creep tendency
Solution Approach 1:
The plastic rolling piston is divided into two separately manufactured parts (support tube and bellows seat) that are connected through a welding or bonding process. This segmentation allows each part to be optimized for its specific function and stress pattern, improving overall stress distribution while maintaining manufacturing efficiency through modular production.
Solution Approach 2:
The two-part plastic piston construction creates a composite structure where each plastic component can be made from materials optimized for its specific mechanical requirements. The connection between parts creates a composite assembly that distributes stresses more effectively than a single-piece design, reducing creep tendency under sustained loads.
4Reliability
If the support tube and jacket are sealed, then airtightness is achieved, but additional sealing complexity is introduced
Solution Approach 1:
The support tube and jacket area are designed to form an integrated sealed unit, where the support tube acts as both a structural support element and a sealing boundary. The welding or bonding connection between the support tube and bellows seat creates an airtight seal that prevents air leakage while maintaining structural integrity, eliminating the need for separate sealing components.
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 enables the use of plastic pistons in commercial vehicles with internal stop buffer support, reducing material creep and weight, while maintaining airtightness and high strength with minimal material usage, and avoiding the need for separate corrosion protection.
Implementation Method 1
the support tube pointing into the interior of the jacket area gripping around the tank pipe of the shock absorber
Implementation Method 2
the Bottom zone is supported via the support area on a second shoulder of the support ring on the container tube of the shock absorber
Implementation Method 3
the support area can be sealed against the support ring by means of at least one seal
Implementation Method 4
the jacket area and cover area of the rolling piston can be connected to one another by friction welding
Data Source
Figure 1
AI summary
The air spring-damper module (1) has a shock absorber (2) with a reservoir tube (3). A support ring (4) is designed as an annular flange, and is provided over an end of the shock absorber. A rolling piston (11) is made of two plastic sections, which include a cladding layer (13) and a lid section (12). The cladding layer has a floor area (21) and a support region (22), where an opening is formed at the floor area of the cladding layer.