Pressure-Balanced Mixing Valve for Precise Low-Power Temperature Control

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Solution Overview

Problem

Existing thermostatic mixing valves face challenges in maintaining a constant outlet water temperature due to pressure and temperature fluctuations in supply lines, leading to temperature errors and slow response times, and conventional electric systems require high power consumption and complex electronics.

Innovation Solution

A frictionless, pressure-balanced proportioning valve assembly with a spool and diaphragm seals, driven by a low-power electric motor, which maintains minimal force requirements and reduces friction, allowing for efficient temperature control with a compact mixing chamber and optimized flow path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional proportioning valves with electric drive units are used, then temperature control precision is improved, but power consumption increases and device complexity increases

Engineering Contradiction:
Improvetemperature control precisionVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the conventional electric motor drive system with a purely mechanical self-balancing proportioning valve mechanism. The valve uses pressure-balanced piston and spring elements to automatically adjust hot and cold water flow proportions in response to inlet pressure fluctuations, eliminating the need for electric motors, sensors, and electronic control circuits while maintaining precise temperature control

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

Solution Approach 2:

The proportioning valve is designed to automatically sense and respond to inlet water pressure changes through its internal pressure-balanced mechanism. The system self-regulates the mixing ratio without requiring external power supply or electronic control, with the mechanical elements spontaneously adjusting to maintain constant outlet temperature

Inventive Principle:
Principle #25Self-service

2Measurement precision

If conventional proportioning valves with electric drive units are used, then temperature control precision is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature control precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the conventional electric motor drive system with a purely mechanical self-balancing proportioning valve mechanism. The valve uses pressure-balanced piston and spring elements to automatically adjust hot and cold water flow proportions in response to inlet pressure fluctuations, eliminating the need for electric motors, sensors, and electronic control circuits while maintaining precise temperature control

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

Solution Approach 2:

The invention extracts and removes all electronic components (motors, sensors, control circuits) from the thermostatic mixing valve system, retaining only the essential mechanical proportioning mechanism that inherently provides temperature control through pressure-balanced operation

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If wax element thermostatic valves are used, then device complexity is reduced, but response time increases and temperature precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidresponse time
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The patent replaces the slow-responding wax element thermal expansion mechanism with a direct-acting pressure-balanced mechanical proportioning valve. This mechanical system responds instantaneously to inlet pressure changes by directly adjusting the mixing ratio, achieving fast response times while maintaining simple device architecture

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

4Device complexity

If wax element thermostatic valves are used, then device complexity is reduced, but temperature precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidtemperature precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces the slow-responding wax element thermal expansion mechanism with a direct-acting pressure-balanced mechanical proportioning valve. This mechanical system responds instantaneously to inlet pressure changes by directly adjusting the mixing ratio, achieving fast response times while maintaining simple device architecture

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

The solution achieves precise temperature control with minimal power consumption, reducing temperature errors and response times, and eliminates the need for complex electronics, providing a stable and efficient thermostatic mixing system.

Implementation Method 1

Two seals disposed at both ends of the spool and housing, are configured, by effective area equalization, for pressure balancing of the first tubular water inlet chamber between a first seal and the disk portion, and pressure balancing of the second tubular water inlet chamber between a second seal and the disk portion

Methodology Applied
Scientific EffectPressure balancing: Pascal's Law

Implementation Method 2

Attached drive means, energized by a low power electric motor, axially displacing said spool

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP2227723B1Low power electric operated thermostatic mixing valve
Publication Date: 2022.04.27 NAHALAT ADAR LTD
  • EP2227723B1 patent drawingFigure 1~2
  • EP2227723B1 patent drawingFigure 3~4
  • EP2227723B1 patent drawingFigure 5

AI summary

A frictionless, pressure balanced proportioning valve assembly, for low power electric operated thermostatic cartridge, composed of a housing with spaced apart hot and cold water inlets and intermediate mixed water outlet, flow communicated to a spool bore with a central widened portion; a spool, guided in the spool bore, by widened end portions, is carrying a central widened disk portion, separating the spool bore into two tubular inlet chambers; two diaphragm seals disposed at both ends of the spool and housing, pressure balancing the inlet chambers; a temperature sensor, exposed to the mixed water outlet pathway, generates a signal, readable by a control circuit; a drive unit energized by a low power electric motor, driving past gear train and eccentric shaft, a bendable connecting rod, axially displacing the spool. Axial displacement of the balanced friction-free spool, proportions flow from the hot and cold water inlets to the mixed water outlet.