Thermostatic Mixing Cartridge for Cold-Start Water Saving

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Solution Overview

Problem

Current thermostatic mixing valves do not effectively encourage users to initially open only the cold water outlet, leading to unnecessary hot water consumption, as they lack a mechanism to automatically regulate the flow based on user intent, unlike single-lever mixing valves.

Innovation Solution

A thermostatic mixing valve assembly with a single-degree-of-freedom manual control member that integrates a thermostatic adjusting system, allowing initial cold water supply by rotating the inlet shutter and adjusting the thermostatic element based on temperature, reducing overall dimensions and promoting energy-saving habits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a thermostatic mixing valve is used to automatically regulate temperature and flow, then temperature stability is improved, but hot water consumption increases because users cannot be compelled to initially open only cold water

Engineering Contradiction:
Improvetemperature stabilityVSAvoidhot water consumption
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The inlet shutter is pre-configured to initially open only the cold water inlet mouth, forcing users to start with cold water only. This preliminary action prevents unnecessary hot water consumption at the beginning of each use, while the thermostatic system remains ready to automatically regulate temperature once both inlets are opened.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically transitions from a static single-inlet configuration to a dynamic dual-inlet configuration. The inlet shutter can rotate to switch between opening only the cold inlet and opening both cold and hot inlets, allowing the system to adapt its flow configuration based on user needs while maintaining energy efficiency.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If a single-lever mixing valve is used to allow user discretion in opening cold or hot water, then ease of operation is improved, but hot water consumption increases due to lack of automatic regulation

Engineering Contradiction:
Improveuser control flexibilityVSAvoidhot water consumption
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The inlet shutter is pre-configured to initially open only the cold water inlet mouth, forcing users to start with cold water only. This preliminary action prevents unnecessary hot water consumption at the beginning of each use, while the thermostatic system remains ready to automatically regulate temperature once both inlets are opened.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The thermostatic element assembly provides automatic feedback control by sensing the temperature of mixed water and automatically adjusting the thermostatic shutter to maintain the desired temperature. This eliminates the need for manual adjustment and prevents energy waste from improper mixing.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If dual-control thermostatic mixing valves are used to separately control temperature and flow, then temperature and flow control precision are improved, but device complexity increases

Engineering Contradiction:
Improvetemperature and flow control precisionVSAvoidnumber of controls
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The manual control member integrates both temperature control and flow rate control functions into a single lever operation. Rotating the lever performs a control stroke that simultaneously adjusts the inlet shutter position (controlling flow rate) and the thermostatic element position (controlling temperature), eliminating the need for separate knobs or levers.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single manual control member serves multiple functions: it controls the inlet shutter to regulate total flow rate, it actuates the thermostatic element to regulate temperature, and it provides a unified user interface for both adjustments. This multi-functional design reduces device complexity while maintaining precise control.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Volume of moving object

If the inlet shutter rotates around an axis parallel to the adjustment direction, then the overall dimensions of the valve assembly are reduced, but the mechanical design complexity increases

Engineering Contradiction:
Improvevalve assembly dimensionsVSAvoidmechanical design complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The inlet shutter rotation axis is oriented parallel to the thermostatic adjustment direction (axial direction) rather than perpendicular to it. This dimensional reorientation allows the shutter and thermostatic elements to be arranged coaxially, reducing the radial dimensions of the valve assembly and enabling a more compact overall design.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The mechanical linkage system employs an asymmetric arrangement where the adjustment shaft connects the manual control member to both the inlet shutter and thermostatic element through a prismatic coupling mechanism. This asymmetric design optimizes space utilization and reduces the overall valve dimensions while maintaining functional independence of control.

Inventive Principle:
Principle #4Asymmetry

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 ensures that the tap initially dispenses only cold water, reducing hot water consumption and allowing for adjustable flow rate and temperature control, thereby promoting energy efficiency and user compliance with energy-saving practices.

Implementation Method 1

a thermostatic element assembly (15) arranged to actuate the thermostatic shutter (19) by expanding or contracting at least along a predetermined adjustment direction (AR) based on the temperature of the liquid that flows around a thermostatic bulb (17) in the mixing chamber (25)

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3265886B1Mixing valve assembly and tap provided with said valve assembly
Publication Date: 2022.04.06 HUBER CISAL IND SPA
  • EP3265886B1 patent drawingFigure 1
  • EP3265886B1 patent drawingFigure 2
  • EP3265886B1 patent drawingFigure 3

AI summary

Thermostatic mixing cartridge (3) for sanitary taps (1) comprising A) a manual control member (9) arranged to perform a control stroke with a single degree of freedom; B) a thermostatic element assembly (15) arranged to actuate the thermostatic valve (19) expanding or contracting according to the temperature of the liquid that laps around a thermostatic bulb (17) into the mixing chamber (25); C) an adjustment shaft (37) actuated by the manual control member (9) and arranged to C.l) to rotate the inlet shutter (11) so as to open the first (27) and the second inlet mouth (29); and C.2) to move the thermostatic element assembly (15) at least according to the predetermined adjustment direction (AR) so as to adjust the predetermined reference temperature. The. cartridge lends itself to be realised with very small dimensions, forcing a user to open the tap supplied with cold water only, with energy savings.