Piston Accumulator Hydropneumatic Strut Design

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Solution Overview

Problem

The existing hydropneumatic piston-cylinder arrangements for vehicle suspension systems face challenges in manufacturing complexity and cost due to the use of diaphragm accumulators with welded housing shells and intricate membrane fixation, making them difficult and expensive to produce.

Innovation Solution

A hydropneumatic piston-cylinder arrangement featuring a piston accumulator with a simple cylindrical structure, where the accumulator is a free piston guided in a tube, reducing the number of parts and manufacturing complexity, and allowing for a single accumulator design to fit various spring strut lengths, thus lowering production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a diaphragm accumulator with welded housing shells and membrane fixation is used, then the piston-cylinder assembly can be compactly integrated, but the manufacturing complexity and production cost increase significantly

Engineering Contradiction:
Improveintegration compactnessVSAvoidmanufacturing simplicity
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the complex diaphragm accumulator components (welded housing shells, membrane, retaining ring, annular groove) and replaces them with a simple piston accumulator. This extraction removes the manufacturing complexity while preserving the compact integration function through the piston-based design.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the expensive, complex diaphragm accumulator with a simpler, more cost-effective piston accumulator design. The piston accumulator uses basic components (piston, cylinder tube, end cap) that are easier and cheaper to manufacture, while still achieving the required functional performance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Adaptability or versatility

If a diaphragm accumulator with welded housing shells is used, then the accumulator can be integrated into the cylinder housing, but the production cost and manufacturing effort increase

Engineering Contradiction:
Improveintegration capabilityVSAvoidproduction cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The piston accumulator design provides a universal solution that can be integrated into the cylinder housing without requiring specialized welded shells or membrane fixation mechanisms. The piston-based design is a standard, versatile component that simplifies manufacturing while maintaining integration capability.

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

3Strength

If hemispherical housing shells with welded connections are used, then the accumulator housing can be formed, but the manufacturing effort and rational production become difficult

Engineering Contradiction:
Improvehousing structural integrityVSAvoidproduction efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The invention extracts and removes the complex hemispherical shell welding process entirely, replacing it with a simple piston accumulator design using a cylindrical tube and end cap. This extraction eliminates the low-productivity welding operation while maintaining sufficient structural integrity for the application.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical welding process with a simpler assembly approach using a piston in a cylindrical tube. This substitution eliminates the need for skilled welding operations and complex hemispherical shaping, thereby significantly improving production efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution provides a cost-effective and efficient construction of the piston-cylinder arrangement, enabling easier assembly and maintenance, with adjustable spring travel and damping characteristics, while minimizing production costs and simplifying the manufacturing process.

Implementation Method 1

a pneumatic spring accumulator (10), in particular a piston accumulator, arranged in the cylinder housing (4)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a cylinder chamber (12) which is filled with hydraulic fluid and in which a piston (14) is axially movably guided

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP3551907B1Hydropneumatic piston-cylinder assembly
Publication Date: 2022.01.05 HYDAC TECH GMBH
  • EP3551907B1 patent drawingFigure 1~2
  • EP3551907B1 patent drawingFigure 3
  • EP3551907B1 patent drawingFigure 4~5

AI summary

The invention relates to a hydropneumatic piston-cylinder assembly, in particular for use as a suspension strut in vehicle suspension systems, comprising a cylinder housing (4) and a piston (14) guided for axial movement in the cylinder chamber (12) of said cylinder housing, which cylinder chamber is filled with a hydraulic fluid, said piston having a piston rod (24) on one piston side (20), which piston rod is led out of an end of the cylinder chamber (12) in a sealed manner, wherein the hydraulic fluid, which is located in the cylinder chamber (12) on the side of the piston crown (16) facing away from the piston rod (24), can be brought into operative connection with a pneumatic spring accumulator (10). Said hydropneumatic piston-cylinder assembly is characterized in that the pneumatic spring accumulator is a piston-type accumulator (10), which is arranged in the cylinder housing (4).