Hot water tank

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Solution Overview

Problem

Existing hot water storage tanks for domestic use face issues with constant dripping and increased energy and water consumption due to uncontrolled expansion of heated water, and are maintenance-intensive due to vulnerable components like rubber bladders and membranes that are prone to fatigue and calcification.

Innovation Solution

A hot water storage tank with an inelastic, hermetically sealed expansion tank of non-variable volume, connected to a water jet pump, which absorbs expansion water before heating, eliminating the need for additional control elements and preventing contamination, thus ensuring a reliable drip stop and reduced calcification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional control elements like non-return valves and pressure relief valves are added to prevent backflow and manage pressure, then the drip stop function is improved, but the device complexity increases

Engineering Contradiction:
Improvedrip stop reliabilityVSAvoidnumber of control elements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates unnecessary control elements from the system. By carefully calculating the expansion tank volume and positioning it correctly, the invention achieves drip stop functionality without requiring non-return valves, pressure relief valves, or other complex control mechanisms.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the water management function into two distinct components: the water tank for holding water and the inelastic expansion tank for absorbing expansion. This clear segmentation allows each component to perform its specific function without requiring additional control elements to manage interactions between them.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the expansion tank is opened to the outside environment for pressure equalization, then the operation is simplified, but contamination enters the water tank

Engineering Contradiction:
Improvepressure equalizationVSAvoidcontamination
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent uses entirely inelastic materials for the expansion tank construction, eliminating the need for pressure equalization openings. The inelastic tank maintains dimensional stability under pressure changes, achieving both contamination prevention and operational simplicity.

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

Solution Approach 2:

The patent changes the material parameter of the expansion tank from elastic to inelastic, which fundamentally alters the pressure behavior. The inelastic tank does not require pressure equalization openings because it maintains its shape and volume under pressure, thereby preventing contamination while simplifying the design.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the expansion tank volume is increased to accommodate all expansion water, then the drip stop reliability is improved, but the device complexity and space requirements increase

Engineering Contradiction:
Improvedrip stop reliabilityVSAvoidexpansion tank volume
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent positions the inelastic expansion tank to receive expansion water at the earliest possible moment - immediately when the tap is closed and pressure equalization begins. This preliminary action allows the expansion tank to capture expansion water progressively, minimizing the required volume while ensuring drip stop reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies the inelastic property specifically to the expansion tank material, allowing it to maintain a compact, non-variable volume. This local application of inelasticity enables the tank to occupy minimal space while still effectively capturing expansion water through its strategically positioned connection to the water tank.

Inventive Principle:
Principle #3Local quality

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 provides a low-maintenance, reliable drip stop that reduces energy and water consumption by managing expansion within the tank, minimizing parts and preventing contamination, resulting in a compact and efficient design.

Implementation Method 1

a negative pressure is generated in the expansion tank, by means of which water is quickly sucked from the water tank into the expansion tank when the tap is stopped

Methodology Applied
Scientific EffectNegative pressure: Pressure Gradient

Implementation Method 2

an amount of water which corresponds to an expansion quantity occurring when the cold water is heated in the water tank

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2827077B8Hot water tank
Publication Date: 2019.06.12 ROBERT BOSCH GMBH

AI summary

The invention discloses a domestic hot water storage tank comprising a water tank for holding water to be heated and an inelastic expansion vessel with a fixed volume for holding the amount of water present in a fitting connected to the outlet when the water supply stops. The expansion vessel is hermetically sealed from the external environment of the water storage tank and is connected to a water jet pump on the inlet side. In addition to the amount of water on the outlet side, the expansion vessel also holds an amount of water corresponding to the expansion that occurs when the cold water in the water tank is heated. The invention is particularly suitable for providing a pressureless hot water storage tank for domestic use or for domestic appliances, which enables reliable drip-stop operation with a simple, reliable, and low-maintenance design.