Dishwasher Impeller Current Sensing for Water-Level Heater Control

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Solution Overview

Problem

Conventional dishwashers lack an efficient method to determine and maintain the optimal water level for heating, which can lead to overheating or inadequate heating of washing water, affecting cleaning performance.

Innovation Solution

A control method and system for a dishwasher that measures the electric current supplied to the motor while rotating the impeller to determine the water level and adjust the heating of washing water, ensuring it remains within a preset reference range to prevent overheating and maintain effective cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the heater operates continuously to heat washing water, then the heating effectiveness is improved, but the risk of overheating and energy waste increases

Engineering Contradiction:

Improvewashing water temperatureVSAvoidenergy waste

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The control unit measures the electric current consumed by the motor during impeller rotation to detect water level. When the water level reaches a predetermined level (indicated by current reaching reference value), the control unit automatically stops the heater operation. This feedback mechanism prevents overheating and energy waste while ensuring adequate heating.

Inventive Principle:

Principle #23Feedback

2Temperature

If the water level in the housing is increased to improve heating efficiency, then the heating effectiveness is improved, but the risk of water overflow and heater damage increases

Engineering Contradiction:

Improveheating efficiencyVSAvoidwater level control

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The system uses electric current measurement as a feedback signal to detect water level. As water rises and contacts the impeller, the motor's electric current consumption increases. When the current reaches a reference value corresponding to the predetermined safe water level, the control unit stops the heater. This prevents water overflow and heater damage while maintaining heating efficiency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Instead of using traditional mechanical water level sensors or float mechanisms, the system substitutes the measurement of electric current consumed by the motor during impeller rotation as the water level detection method. This non-contact measurement approach improves reliability by avoiding mechanical wear and calibration issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If the impeller rotation speed is increased to improve water circulation, then the water circulation efficiency is improved, but the electric current consumption increases

Engineering Contradiction:

Improvewater circulation efficiencyVSAvoidmotor electric current

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The impeller is rotated at a speed sufficient to achieve the predetermined water level detection, rather than continuously at maximum speed. The control unit stops the impeller rotation once the water level is detected (current reaches reference value), avoiding excessive energy consumption while maintaining adequate water circulation for heating.

Inventive Principle:

Principle #16Partial or excessive action

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

This approach allows for precise control of the water level and heating, enhancing the cleaning efficiency by ensuring the water is heated optimally, preventing overheating, and maintaining consistent performance.

Implementation Method 1

a motor configured to rotate the impeller... rotating the impeller by supplying electricity to the motor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

heating washing water located in the housing by operating the heater based on the amount of electric current supplied to the motor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9844801B2Dishwasher

Publication Date: 2017.12.19 LG ELECTRONICS INC

AI summary

A control method for a dishwasher that includes a spray arm, a sump configured to provide a space where washing water is stored and to collect washing water sprayed from the spray arm, a housing configured to connect the sump and the spray arm, a heater located in the housing, an impeller located in the housing and above the heater, and a motor configured to rotate the impeller, is described. The control method includes the actions of supplying washing water to the sump; rotating the impeller by supplying electricity to the motor; measuring an amount of electric current supplied to the motor during the rotating of the impeller; and heating washing water located in the housing by operating the heater based on the amount of electric current supplied to the motor during the rotating of the impeller being greater than or equal to a preset reference amount.