Piston Accumulator Cylinder Liner Elastic Support

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Solution Overview

Problem

Piston accumulators face challenges in maintaining optimal sealing and guidance due to housing expansion under high internal pressures, leading to increased costs, weight, and complexity in design, as well as limitations in using materials with different thermal and pressure-related expansion behaviors.

Innovation Solution

The use of resiliently or elastically supported liners via support lamellae or lamellar components, which compensate for housing and liner expansions, allowing for thinner designs and simpler connections, and the incorporation of an elastomer matrix for enhanced safety and gas-tightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the housing wall thickness is increased to maintain rigidity under high internal pressure, then the housing strength is improved, but the weight and cost of the piston accumulator increase

Engineering Contradiction:
Improvehousing strengthVSAvoidhousing weight
Core Design Contradiction:
StrengthVSWeight of stationary object

Solution Approach 1:

The housing is made from fiber-reinforced plastic material, specifically carbon fiber-reinforced plastic (CFRP) or glass fiber-reinforced plastic (GFRP). These composite materials provide high strength-to-weight ratio, allowing the housing to maintain sufficient rigidity and strength under high internal pressure while keeping the wall thickness and overall weight reduced compared to traditional solid metal constructions.

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the housing diameter is enlarged to accommodate larger pistons, then the piston size is improved, but the sealing and guidance function of the piston deteriorates due to housing expansion

Engineering Contradiction:
Improvepiston volumeVSAvoidpiston sealing and guidance
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The cylinder liner is designed with elastic support elements that allow it to dynamically adapt to housing expansion. The support elements include elastic deformation capability, enabling the cylinder liner to move and deform elastically when the housing expands under pressure, thereby maintaining constant contact and sealing against the piston while preserving proper piston guidance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cylinder liner is designed with changed material parameters, specifically using elastomeric materials or plastics with appropriate elastic modulus. This allows the cylinder liner to exhibit elastic deformation behavior, changing its dimensional parameters dynamically in response to housing expansion, thereby maintaining sealing and guidance functions despite diameter changes.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If materials with different thermal and pressure expansion behaviors are used for the housing and cylinder liner, then the adaptability is improved, but leaks and internal stresses occur

Engineering Contradiction:
Improvematerial selection flexibilityVSAvoidsealing reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The elastic support elements enable the cylinder liner to dynamically adjust its position and shape in response to differential expansion between the housing and liner materials. This dynamic adaptation accommodates thermal and pressure expansion differences without creating excessive stresses or leaks, allowing genuine material selection flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cylinder liner is designed as a flexible component with elastic properties, allowing it to deform and adapt to housing expansion. This flexibility compensates for the different expansion behaviors of dissimilar materials, maintaining sealing integrity and preventing leaks despite thermal and pressure cycling.

Inventive Principle:
Principle #30Flexible shells and thin films

4Stability of the object's composition

If the cylinder liner is rigidly supported at both ends to withstand external accelerations, then the structural stability is improved, but the entire system is stressed by different expansion rates

Engineering Contradiction:
Improvecylinder liner stabilityVSAvoidsystem stress
Core Design Contradiction:
Stability of the object's compositionVSStress or pressure

Solution Approach 1:

Instead of rigid fixed supports, the invention uses elastic support elements that provide dynamic stabilization. These elements allow the cylinder liner to move and deform elastically in response to both external accelerations and thermal/pressure expansion, maintaining structural stability while accommodating differential expansion rates without excessive stress accumulation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The support elements are designed with specific elastic parameters that allow them to change their stiffness characteristics. Under external acceleration, they provide sufficient support stability, while under thermal and pressure loading, they allow controlled deformation to accommodate expansion differences, thereby managing system stresses.

Inventive Principle:
Principle #35Parameter changes

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 solution ensures effective sealing and guidance of the piston while optimizing strength, weight, and cost, allowing for the use of diverse materials and reducing the risk of component failure under pressure and temperature changes.

Implementation Method 1

The cylinder liner (6) is spring-loaded and/or elastically supported against the housing (1) by support lamellae (12)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

These have a matrix, namely a binding system, made of epoxy resins. However, thermoplastics are already known for this purpose. These exhibit brittle behavior

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3067570B1Piston accumulator
Publication Date: 2019.10.09 CARL FREUDENBERG KG
  • EP3067570B1 patent drawingFigure 1
  • EP3067570B1 patent drawingFigure 2
  • EP3067570B1 patent drawingFigure 3

AI summary

A piston accumulator comprising a housing (1) which defines a pressure chamber (2) and accommodates a movable piston (3), wherein a compressible fluid is accommodated in the pressure chamber (2), wherein the piston (3) has a housing side (4) which faces the pressure chamber (2) and wherein the piston (3) has a working side (5) which is oriented towards a working fluid which can move the piston (3), is characterized with regard to the objective of providing a piston accumulator in which good sealing and guidance of the piston are ensured even if the diameter of the housing undergoes an expansion, wherein the strength, weight and cost of the piston accumulator are optimized as far as possible, in that a cylinder liner (6) is provided within which the piston (3) is movable.