Dual-Shell Plastic Pump Housing with Foam Fill

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Solution Overview

Problem

Existing centrifugal pump housings face challenges in corrosion resistance, particularly when handling aggressive media, as conventional designs risk corrosion both internally and externally, and complex plastic housings are costly and difficult to produce.

Innovation Solution

A pump housing design featuring two dimensionally stable shells with a filling material in between, allowing independent production and damping of vibrations, using self-foaming foam for expansion without pressure build-up, and incorporating reinforcement elements and fiber-reinforced composite materials for enhanced stability and chemical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plastic inner lining is used to protect against corrosion from aggressive media, then corrosion resistance is improved, but the risk of liner detachment due to pressure differences increases

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidliner detachment risk
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent implements a nested structure with an inner shell (liner) and an outer shell, where the inner shell is positioned within the outer shell at a defined distance. This nested configuration allows the inner lining to provide corrosion resistance while the outer shell and spacing structure prevent detachment by accommodating pressure differences without direct contact between the liner and housing walls.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent introduces an intermediate spacing structure (distance between inner and outer shells) that acts as a mediator to decouple the inner lining from the outer housing. This intermediate space allows pressure equalization and prevents the direct transmission of pressure differences that would cause liner detachment, while still maintaining the corrosion protective function of the inner shell.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a housing is made entirely of plastic to eliminate corrosion risk, then corrosion resistance is improved, but manufacturing complexity and cost increase for complex housing shapes

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the housing into two separate shell components (inner shell and outer shell) that can be manufactured independently. This segmentation allows each shell to be produced using simpler, more cost-effective processes suitable for its specific functional requirements, rather than requiring a single complex plastic molding operation for the entire housing assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a composite structure combining inner and outer shell materials, where each shell can be optimized for its specific function. The inner shell uses corrosion-resistant plastic material, while the outer shell can use different materials or structures optimized for structural support and manufacturing efficiency, resulting in a composite housing system that balances corrosion resistance with manufacturing simplicity.

Inventive Principle:
Principle #40Composite materials

3Strength

If the inner and outer housings are in positive contact to provide structural support, then mechanical stability is improved, but the risk of corrosion between housing and coating increases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidcorrosion between housing and coating
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediate spaced gap between the inner and outer shells that prevents direct contact between the two components. This intermediate space acts as a protective barrier that eliminates the corrosion pathway that would exist in positive contact configurations, while still providing mechanical stability through the structural design of the spaced shell assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the direct contact interface between inner and outer shells by introducing a spaced separation. This removal of the contact interface eliminates the source of corrosion that would occur at the boundary between housing and coating, while the overall structural stability is maintained through the engineered spacing and support structure.

Inventive Principle:
Principle #2Taking out (Extraction)

4Strength

If foam material is used to fill the space between shells for support, then structural support is improved, but complex mechanical processing is required

Engineering Contradiction:
Improvestructural supportVSAvoidmechanical processing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent employs self-foaming foam material that automatically expands to fill the space between the inner and outer shells without requiring external foaming equipment or complex mechanical processing. The foam's self-foaming property allows it to perform the filling and support function autonomously, eliminating the need for complex manufacturing steps to introduce and expand conventional foam materials.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent utilizes the parameter change of foam material from liquid precursor to expanded foam structure through self-foaming chemistry. This parameter change occurs automatically within the confined space between shells, providing structural support through the expansion process itself without requiring external mechanical intervention or complex processing equipment.

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

The design provides a stable, cost-effective, and corrosion-resistant pump housing that can be easily manufactured from standardized segments, adaptable to various applications, with reduced risk of corrosion and improved mechanical and chemical stability.

Implementation Method 1

the filling material is a self-foaming foam, in particular a foam that expands without pressure build-up

Methodology Applied
Scientific EffectSelf-foaming expansion: Foam

Implementation Method 2

a filling material can be chosen in such a way that possible vibrations between the two shells are reduced by damping in the filling material

Methodology Applied
Scientific EffectVibration damping: Damping

Implementation Method 3

Another possibility is the reduction of heat transfer between the two shells through a corresponding heat-insulating filling material

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3077679B1Plastic pump casing made of an inner shell and an outer shell, with filling material in between
Publication Date: 2020.02.26 KSB SE & CO KGAA
  • EP3077679B1 patent drawingFigure 1
  • EP3077679B1 patent drawingFigure 2

AI summary

The invention relates to a pump housing made of plastic. Said housing is provided with a first casing that has a first side facing the pumped medium, and a second casing that has a second side facing the environment. The pump housing is characterized in that the first casing and the second casing are both dimensionally stable and in that there is a space between the first casing and the second casing.