Beverage machine with non-isolated power supply for liquid contacting components

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Solution Overview

Problem

Beverage machines using non-isolated power supplies risk electrical shocks when components contact beverage liquids, as they lack physical separation between input and output power circuits, making them unsafe despite being more efficient and cost-effective than isolated power supplies.

Innovation Solution

A beverage machine design that employs a non-isolated power supply for liquid-contacting components, such as sensors, by limiting the maximum current delivered to the liquid to less than 2 milliamps and using a common ground or neutral for input and output power, ensuring safe operation while allowing the use of non-isolated power supplies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an isolated power supply is used to power liquid-contacting components, then user safety is improved by preventing electrical shocks, but device cost and energy consumption increase

Engineering Contradiction:

Improveuser safetyVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the electrical parameters of the liquid-contacting circuit by implementing current limiting (maximum 10 microamps) and voltage monitoring. This allows the use of a non-isolated power supply while maintaining safety through parameter control rather than physical isolation, thereby reducing energy consumption and cost.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary current-limiting circuit between the power supply and the liquid-contacting sensor. This intermediary component prevents harmful current flow while allowing the use of a simpler non-isolated power supply, resolving the contradiction between safety and energy efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an isolated power supply is used to power liquid-contacting components, then user safety is improved by preventing electrical shocks, but device cost increases

Engineering Contradiction:

Improveuser safetyVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses inexpensive current-limiting resistors and simple voltage monitoring circuits instead of expensive isolated power supply components. These cheap protective elements provide adequate safety while significantly reducing manufacturing cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Loss of energy

If a non-isolated power supply is used to power liquid-contacting components, then device cost and energy consumption are reduced, but user safety deteriorates due to risk of electrical shocks

Engineering Contradiction:

Improveenergy consumptionVSAvoidelectrical shock risk

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary protective measures by implementing current limiting and voltage monitoring before any harmful current can reach the liquid or user. This preliminary anti-action eliminates the electrical shock risk while allowing the use of energy-efficient non-isolated power supplies.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent controls the electrical parameters (current limited to 10 microamps, voltage monitored) of the liquid-contacting circuit to prevent harmful effects. This parameter control eliminates the electrical shock risk while maintaining energy efficiency.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If a non-isolated power supply is used to power liquid-contacting components, then device cost and energy consumption are reduced, but user safety deteriorates due to lack of physical separation between input and output circuits

Engineering Contradiction:

Improvedevice costVSAvoidelectrical shock risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent compensates for the lack of physical separation by implementing strict parameter control (current limiting to 10 microamps, voltage monitoring). This allows the use of cost-effective non-isolated power supplies while maintaining user safety through electrical parameter management.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces intermediary current-limiting circuits and voltage monitoring as mediators between the non-isolated power supply and the liquid-contacting components. These intermediaries provide the necessary safety protection without requiring physical isolation, enabling cost-effective design.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20230404320A1Beverage machine with non-isolated power supply for liquid contacting components

Publication Date: 2023.12.21 KEURIG GREEN MOUNTAIN INC

AI summary

Methods and systems for electrically powering liquid-contacting components of a beverage machine using a non-isolated power supply.