Dryer Motor Current Sensing for Accurate Laundry Amount Detection

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Solution Overview

Problem

Conventional clothes dryers face challenges in accurately determining the amount of laundry, leading to inconsistent drying times and potential damage to clothes due to fixed drying settings, and existing methods are not effectively adaptable to the weight and moisture content of wet laundry, resulting in inefficient drying and user inconvenience.

Innovation Solution

A clothes dryer with a controller that uses a specific operation pattern involving acceleration and maintaining stages to sense the laundry amount through motor current measurement, adjusting rotation speed to prevent sticking and ensure accurate drying, thereby optimizing drying time and energy usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed drying time is set according to laundry type rather than amount, then the drying operation can be simplified and operated easily, but the drying efficiency decreases and energy consumption increases due to inability to adapt to actual laundry amount

Engineering Contradiction:
Improveease of operationVSAvoiddrying efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The dryer automatically senses the laundry amount through motor current detection and self-adjusts the drying time without user intervention. The controller measures current during acceleration and maintaining stages, calculates laundry amount, and sets appropriate drying time automatically, making the system self-adaptive while maintaining ease of operation

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual time-setting mechanisms with electronic sensing and calculation systems. Motor current is electronically measured and processed to determine laundry amount, which then automatically controls drying time parameters, substituting mechanical adjustment with electronic intelligence

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

2Productivity

If temperature is increased to accelerate drying speed, then drying efficiency improves, but laundry damage occurs due to excessive heat

Engineering Contradiction:
Improvedrying speedVSAvoidlaundry damage
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic adjustment of drying parameters based on sensed laundry amount. The drying time is dynamically optimized to match actual laundry quantity, and temperature is dynamically adjusted during different stages (higher initially, then reduced near completion), preventing both under-drying and heat damage

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The drying process uses periodic temperature adjustment with multiple stages: initial high-temperature phase for rapid moisture removal, followed by reduced temperature phase to complete drying without damage. The system periodically monitors and adjusts temperature based on drying progress and laundry amount

Inventive Principle:
Principle #19Periodic action

3Productivity

If the drum rotation speed is increased to prevent laundry sticking, then drying performance improves, but measurement accuracy of laundry amount decreases due to laundry movement and initial position variations

Engineering Contradiction:
Improvedrying performanceVSAvoidlaundry amount measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs laundry amount sensing during the acceleration stage before the drum reaches high rotation speed. By measuring motor current during this preliminary phase when laundry movement is minimal, the system accurately determines laundry amount before drying begins, avoiding measurement errors from high-speed rotation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors motor current throughout the acceleration and maintaining stages to track laundry amount. This continuous measurement approach ensures accurate sensing regardless of drum speed variations, maintaining both measurement precision and drying performance

Inventive Principle:
Principle #20Continuity of useful 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

The solution enables precise determination of laundry amount and tailored drying operations, reducing drying time, preventing damage, and enhancing user convenience by ensuring complete and efficient drying while minimizing energy consumption.

Implementation Method 1

a motor connected with the drum via a drive belt and configured to rotate the drum

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

a current sensing unit configured to measure a current value of the motor

Methodology Applied
Scientific EffectElectrical current measurement: Ohm's Law

Data Source

PatentEP3492649B1Dryer and method of controlling the same
Publication Date: 2021.07.14 LG ELECTRONICS INC
  • EP3492649B1 patent drawingFigure 1
  • EP3492649B1 patent drawingFigure 2~3
  • EP3492649B1 patent drawingFigure 4~5

AI summary

A dryer (1) and a method for quickly and accurately determining an amount of laundry (9) loaded in the dryer and controlling a drying operationaccording to the amount of the laundry: measuring a current supplied to rotate the drum (30) and extracting a force applied to laundry in the drum to measure an amount of the laundry, thereby minimizing an error in the amount of laundry and thus enhancing accuracy of the measurement and improving a drying time; setting a drying time in consideration of both a calculated amount of laundry and a type of the laundry, such that damage to the laundry is prevented and over-drying or less-drying of the laundry is solved.