In-situ Foam Curing for Hydraulic Accumulator Separating Layers

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Solution Overview

Problem

The existing methods for producing pressure accumulators with foam bodies are complex, costly, and prone to damage during the introduction of ready-foamed foam materials, which limits their design as disposable components and increases production expenses.

Innovation Solution

A method involving the introduction of a flowable foam material into the pressure accumulator, where it cures in situ, expanding the separating layer to form a finished foam block, avoiding the need for pre-formed blocks and minimizing damage, using a lance-shaped introduction device to ensure targeted and uniform filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pre-formed foam blocks are inserted into the pressure accumulator, then high storage capacity and damping stiffness are achieved, but damage to the foam and elastomeric separating layer is unavoidable during insertion

Engineering Contradiction:
Improveintegrity of foam and separating layerVSAvoidcomplexity of assembly process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The foam material is introduced in a different physical state (liquid or semi-liquid precursor) rather than pre-formed solid blocks. The material transforms from liquid to solid foam through in-situ foaming and curing processes, changing its physical parameters during insertion to avoid mechanical damage

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The foam material undergoes phase transition from liquid/semi-liquid precursor state to solid foam structure after introduction into the accumulator. This phase change occurs in-situ, allowing the material to flow during insertion and then solidify to provide structural support without damaging other components

Inventive Principle:
Principle #36Phase transitions

2Ease of manufacture

If the storage housing is divided into several segments to facilitate foam insertion, then ease of assembly is improved, but production becomes labor-intensive and costly

Engineering Contradiction:
Improveease of foam insertionVSAvoidnumber of segments and joining operations
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The foam precursor material is introduced using fluid delivery systems (pumps, hoses, injection devices) that can deliver the liquid foam material through existing access openings in the storage housing, eliminating the need to divide the housing into segments

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The foam material self-expands and self-structures after introduction, filling the available space and forming the required foam structure without requiring manual assembly operations or multiple housing segments

Inventive Principle:
Principle #25Self-service

3Quantity of substance

If pre-cured foam blocks are used, then storage capacity is maximized, but the manufacturing process is complex and costly

Engineering Contradiction:
Improvestorage capacityVSAvoidproduction efficiency
Core Design Contradiction:
Quantity of substanceVSProductivity

Solution Approach 1:

The foam precursor material is prepared in liquid form before introduction, allowing it to be delivered through simple access openings. The actual foaming and curing actions occur after introduction, eliminating the need for complex pre-foaming and pre-curing operations outside the accumulator

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The mechanical process of inserting pre-formed foam blocks is replaced by a chemical process where liquid precursor material is pumped and injected, then transforms chemically into solid foam in-situ. This substitution eliminates mechanical handling complexity

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

This approach simplifies the production process, reduces costs, and ensures high storage capacity with improved temperature and pressure stability, while avoiding damage to the foam and elastomeric materials, enabling efficient and cost-effective manufacturing of functionally reliable pressure accumulators.

Implementation Method 1

introducing a flowable, preferably liquid, foam material into the pressure accumulator

Methodology Applied
Scientific EffectFoaming: Foam

Implementation Method 2

curing the foam material in the pressure accumulator

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Implementation Method 3

the increasingly curing foam material widens the separating layer from an initially partially filled initial state towards a final state

Methodology Applied
Scientific EffectVolume expansion during curing: Phase Change

Data Source

PatentEP3271591B1Method for producing a foam body
Publication Date: 2020.08.05 HYDAC TECH GMBH
  • EP3271591B1 patent drawingFigure 1~3

AI summary

A method for producing a foam body, in particular for a pressure accumulator, such as a hydraulic accumulator, the bubble- or diaphragm-shaped, elastically flexible separating layer (12) of which separates two media chambers from each other within the accumulator housing, in particular a gas working chamber from a liquid chamber (18), with at least the following production method steps: – introducing a flowable, preferably liquid, foam material into the pressure accumulator, said foam material being at least partially surrounded by the separating layer (12), – curing the foam material in the pressure accumulator, and in the process – building up a pressure gradient, in which the visibly curing foam material expands the separating layer (12) from an originally partially filled starting state in the direction of an end state, in which the accumulator is finally filled with the cured foam (38).