Rib-Stiffened Rolling Piston for Uniform Air Spring Stress

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Solution Overview

Problem

Existing rolling pistons in air suspension systems face issues with uneven mechanical stress distribution due to small contact surfaces, leading to high point loads and increased material costs, weight, and complexity, which are not ideal for weight reduction and cost-effectiveness.

Innovation Solution

A rolling piston design featuring a cup-shaped lower part with a rotationally symmetrical piston crown and wall, supported by rib-like stiffening elements and a transition element, which converts shear stresses into compressive stresses for uniform stress distribution, allowing for a thinner wall and reduced material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the wall thickness of the rolling piston is increased to withstand high point loads from small contact surfaces, then the strength and reliability improve, but the weight and material costs increase

Engineering Contradiction:
ImprovestrengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The piston crown is segmented into multiple contact surfaces arranged in a circular pattern, distributing the load across several distinct areas rather than relying on a single large contact surface. This segmentation allows the use of thinner walls while maintaining strength, as each segment handles a portion of the total load.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The contact surfaces are arranged in a three-dimensional circular pattern on the piston crown, utilizing the radial dimension to distribute loads. This dimensional arrangement transforms the stress distribution from concentrated point loads to distributed loads across multiple surfaces, reducing the required wall thickness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If additional components like supports and stiffening elements are added to the rolling piston, then the structural stability and stress distribution improve, but the device complexity and manufacturing costs increase

Engineering Contradiction:
ImprovestabilityVSAvoidcomplexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The piston crown is integrated directly into the piston body as a unified structure, eliminating the need for separate support components. The multiple contact surfaces are formed as part of the piston crown itself, combining the functions of load distribution and structural support into a single component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The piston crown serves multiple functions simultaneously: it provides the bearing surface for load application, acts as a stiffening element through its geometric design with multiple contact surfaces, and maintains structural integrity. This multi-functionality eliminates the need for additional specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Weight of moving object

If the contact surface area of the piston crown is kept small to reduce material usage, then the weight and material costs decrease, but the stress distribution becomes uneven and point loads increase

Engineering Contradiction:
ImproveweightVSAvoidstress distribution
Core Design Contradiction:
Weight of moving objectVSStress or pressure

Solution Approach 1:

The total contact area is divided into multiple smaller contact surfaces arranged in a circular pattern. This segmentation distributes the applied load across several discrete areas, preventing concentration of stress at any single point while maintaining an overall small contact footprint for weight reduction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each contact surface on the piston crown is optimized for its specific local stress conditions. The circular arrangement ensures that each local area receives appropriate load distribution, with the geometry of each contact surface tailored to handle the specific stress patterns it encounters during operation.

Inventive Principle:
Principle #3Local quality

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 uniform stress distribution, reduces material usage and weight, and lowers production costs, enhancing the payload capacity of commercial vehicles while preventing local overloading and stress peaks.

Implementation Method 1

rib-like stiffening elements, which convert shear stresses into compressive stresses for uniform stress distribution

Methodology Applied
Scientific EffectStress transformation: Shear Stress

Data Source

PatentEP4180246B1Rolling piston
Publication Date: 2024.08.21 CONTITECH DEUTSCHLAND GMBH
  • EP4180246B1 patent drawingFigure 1
  • EP4180246B1 patent drawingFigure 2
  • EP4180246B1 patent drawingFigure 3

AI summary

The invention relates to a rolling piston (2) of an air spring system (4), comprising a cup-shaped piston lower part (6), wherein the piston lower part (6) has a piston base (10) with a bearing surface (11) and a rotationally symmetrical piston wall (12), a piston upper part (8) designed as a cover, which is airtightly connected to the piston lower part (6) and adjoins the piston wall (12), wherein several rib-like stiffening elements (14) are arranged rotationally symmetrically in the radial direction (R), in particular radially to a longitudinal axis (X) extending normal to the piston base (10), wherein the rib-like stiffening elements (14) have a first side surface (24) and a second side surface (26), wherein the piston upper part (8) has a flange (20) and a frame (22), wherein the frame (22) extends axially away from the piston base (10). protrudes from the flange (20) by a predetermined amount.According to the invention, the piston base (10) has a circumferential groove (13) which is arranged rotationally symmetrically in the radial direction (R) and has a predetermined radius.