Plastic Stuffing Box Housing for Heat Exchanger Valves

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Solution Overview

Problem

Existing heat exchanger valves face challenges in cost-effectiveness and reliability due to the use of metallic materials, particularly brass, which are expensive and require machining, and suffer from loose connections under changing heat conditions.

Innovation Solution

A heat exchanger valve with a stuffing box housing made of plastic material, utilizing thread-free connections such as bajonett-connections, snap connections, or spring rings for assembly, allowing for low-cost production and secure attachment without tools, and incorporating sealing elements to prevent fluid leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic material (brass) is used for stuffing box housing, then connection reliability is improved, but production cost increases and machining complexity increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive metallic stuffing box housing with inexpensive plastic material. The plastic housing is designed as a disposable or replaceable component that can be easily manufactured through injection molding, eliminating the need for costly metal machining while maintaining sufficient service life for the application.

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

Solution Approach 2:

The patent changes the material parameter from metal to plastic, which fundamentally alters the manufacturing approach. Plastic materials allow for injection molding processes that are far more cost-effective and less complex than metal machining, while the material properties are selected to withstand the operational conditions of the valve.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If metallic material (brass) is used for stuffing box housing, then connection reliability is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidmachining complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical machining process with an injection molding process. Instead of cutting and shaping metal through complex machining operations, the plastic housing is formed directly through mold injection, significantly simplifying the manufacturing process and reducing device complexity.

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

Solution Approach 2:

The patent changes the material parameter from metal to plastic, which fundamentally alters the manufacturing approach. Plastic materials allow for injection molding processes that are far more cost-effective and less complex than metal machining, while the material properties are selected to withstand the operational conditions of the valve.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If plastic material is used for stuffing box housing, then production cost is reduced and ease of manufacture is improved, but connection reliability deteriorates under changing heat conditions

Engineering Contradiction:
Improveproduction costVSAvoidconnection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent incorporates a thread-locking mechanism or sealing elements during the injection molding process itself. The housing is designed with integrated features such as threaded inserts or snap-fit connections that are formed as part of the molding process, ensuring reliable assembly before the product even leaves the factory. This preliminary action prevents connection issues from developing during operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent may use composite plastic materials or combine plastic with metal inserts (such as threaded bronze inserts or steel reinforcement ribs) to maintain the cost and manufacturing advantages of plastic while incorporating the thermal stability and connection reliability of metal components. This composite approach allows the plastic housing to benefit from metal's dimensional stability under temperature changes.

Inventive Principle:
Principle #40Composite materials

4Ease of operation

If thread connection is used for plastic stuffing box housing, then ease of assembly is improved, but connection reliability deteriorates under elevated temperatures

Engineering Contradiction:
Improveease of assemblyVSAvoidconnection reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent incorporates a thread-locking mechanism or sealing elements during the injection molding process itself. The housing is designed with integrated features such as threaded inserts or snap-fit connections that are formed as part of the molding process, ensuring reliable assembly before the product even leaves the factory. This preliminary action prevents connection issues from developing during operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent may use composite plastic materials or combine plastic with metal inserts (such as threaded bronze inserts or steel reinforcement ribs) to maintain the cost and manufacturing advantages of plastic while incorporating the thermal stability and connection reliability of metal components. This composite approach allows the plastic housing to benefit from metal's dimensional stability under temperature changes.

Inventive Principle:
Principle #40Composite materials

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 enables cost-effective production and reliable operation by using plastic materials for the valve components, ensuring secure attachment and effective sealing without the need for machining or threaded connections, maintaining integrity under varying temperatures.

Implementation Method 1

A stuffing box made of a plastic material tends to flow under changing heat conditions and elevated temperatures

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The pin is guided through the stuffing box means and sealed therein to prevent heating fluid to escape to the outside

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP3193060B1Valve, in particular heat exchanger valve
Publication Date: 2019.04.03 DANFOSS AS
  • EP3193060B1 patent drawingFigure 1
  • EP3193060B1 patent drawingFigure 2
  • EP3193060B1 patent drawingFigure 3

AI summary

A valve, in particular a heat exchanger valve (1) is described comprising a housing arrangement (2, 5, 6, 7), a valve element (10) within said housing arrangement (2, 5, 6, 7), stuffing box means (14) comprising a stuffing box housing (15) and being connected to said housing arrangement (2, 5, 6, 7), and a pin (12) slidingly accommodated within said stuffing box means (14). Such a heat exchanger valve should be produced with low costs. To this end said stuffing box housing (15) is made of a plastic material.