Variable-Circumference Valve Screen for Tool-Free Sealing

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Solution Overview

Problem

Existing thermostatic valves face issues with strainers that are either welded and non-removable, leading to maintenance challenges, or clipped with additional O-rings, increasing costs and risk of damage or injury, while not providing a tight seal, especially with hard water and temperature fluctuations.

Innovation Solution

A removable, tool-free, annular sieve with a thin-walled hollow cylinder design that expands by hand, featuring a larger circumference for improved sealing and ease of maintenance, made of plastic without threads or wires, and using a spring element for expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the strainer is welded onto the valve body, then the strainer is firmly bonded and cannot be removed, but maintenance becomes impossible and the strainer cannot be cleaned

Engineering Contradiction:
Improvebonding strengthVSAvoidmaintenance accessibility
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The strainer is designed as a separate, removable component that can be detached from the valve body without tools. This segmentation allows the strainer to be firmly bonded during operation for strong filtering, yet easily separated for maintenance and cleaning by simply pulling it outward.

Inventive Principle:
Principle #1Segmentation

2Ease of repair

If the strainer is clipped onto the valve body with additional O-rings, then the strainer can be removed, but production cost increases and the risk of damage or injury increases

Engineering Contradiction:
Improvemaintenance accessibilityVSAvoidstructure complexity
Core Design Contradiction:
Ease of repairVSDevice complexity

Solution Approach 1:

The complex clipping mechanism with O-rings is completely removed. The strainer uses a simple friction-fit design where the circumferential spring element provides enough elastic force for secure bonding during operation, but allows tool-free removal by simply pulling the strainer outward without any additional fastening components.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If the strainer is simply clipped on without additional securing elements, then production cost decreases, but the strainer may not fit perfectly and tolerance gaps occur leading to damage or injury

Engineering Contradiction:
Improvestructure complexityVSAvoidsealing fit
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The strainer employs a friction-fit mechanism where the circumferential spring element is elastically deformed during installation to a larger circumference. This elastic deformation creates sufficient friction force to securely bond the strainer to the valve body, ensuring a tight seal without tolerance gaps, while still allowing easy tool-free removal.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If the strainer is made with a fixed circumference, then manufacturing is simpler, but the strainer cannot be universally suitable for thermostatic valves of different diameters

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcompatibility range
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The strainer features a dynamic circumference that can change between two states: a smaller circumference for easy insertion and a larger circumference for secure bonding. This dynamic adjustment, achieved through the elastic circumferential spring element, allows a single strainer design to universally fit thermostatic valves of different diameters while maintaining simple manufacturing.

Inventive Principle:
Principle #15Dynamics

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 sieve provides a secure, cost-effective, and injury-free maintenance solution with enhanced sealing, suitable for various diameters, reducing waste and ensuring long service life by preventing suspended matter entry.

Implementation Method 1

using a spring element for expansion

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3934785B1Screen having variable circumference for a thermostatic valve
Publication Date: 2025.06.25 GROHE AG
  • EP3934785B1 patent drawingFigure 1
  • EP3934785B1 patent drawingFigure 2
  • EP3934785B1 patent drawingFigure 3a~3b

AI summary

The present invention relates to a screen. The screen a) is annular, b) is designed to filter water in a thermostatic valve, c) can be transferred from a first state into an additional state, d) has a first circumference in the first state, and e) has an additional circumference in the additional state. The screen is characterized in that the additional circumference is greater than the first circumference. The invention also relates to a thermostatic valve comprising the screen; to a thermostat fitting comprising the thermostatic valve; to a method comprising connecting the screen to a thermostatic valve body; and to a use of the screen in a thermostatic valve or in a thermostat fitting or in both.