Refrigerator Active Noise Cancellation for Variable-Speed Compressor

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Solution Overview

Problem

Existing refrigerators struggle to effectively reduce noise generated by the compressor, which varies in frequency with changes in rotation speed, and this noise often leaks through the side surfaces of the machine room, affecting the efficiency of the compressor and condenser.

Innovation Solution

A noise reduction device with sensing units and a generator unit that measures and cancels noise at the source, using microphones and speakers to emit opposing frequencies to reduce noise leakage through the side surfaces, while maintaining efficient cooling of the compressor and condenser.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a resonance device is used to reduce compressor noise, then noise in specific frequency is reduced, but noise at different frequencies caused by varying rotation speeds is not reduced

Engineering Contradiction:
Improvecompressor noiseVSAvoidnoise reduction effectiveness across different rotation speeds
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent uses an active noise control system with microphones, processors, and speakers that dynamically adjust the anti-noise signal based on real-time detection of compressor noise characteristics. This dynamic adaptation allows the system to effectively reduce noise across varying rotation speeds and frequencies, overcoming the limitation of fixed-frequency resonance devices.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms where microphones detect the actual noise generated by the compressor, and the processor uses this information to generate appropriate anti-noise signals through speakers. This closed-loop feedback enables continuous optimization of noise reduction effectiveness regardless of changes in compressor rotation speed.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the machine room is enclosed to reduce noise transmission, then noise is reduced, but heat dissipation from the compressor and condenser becomes inefficient

Engineering Contradiction:
Improvenoise transmissionVSAvoidheat dissipation efficiency
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent employs acoustic absorption materials and vibration isolation structures that act as flexible barriers within the machine room. These materials reduce noise transmission while maintaining thermal properties that allow effective heat dissipation, resolving the contradiction between noise reduction and thermal management.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The system uses vibration isolation mounts and acoustic absorption materials as intermediary elements between the noise sources (compressor, condenser) and the machine room enclosure. These intermediaries attenuate noise transmission while preserving the thermal environment necessary for efficient heat dissipation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If vibration isolation structures are added to reduce compressor vibrations, then vibrations and noise are reduced, but device complexity increases

Engineering Contradiction:
Improvevibrations and noiseVSAvoidstructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent employs relatively simple and cost-effective vibration isolation components such as rubber mounts and foam absorption materials. These inexpensive elements provide effective vibration and noise reduction without significantly increasing structural complexity, making the solution practical for implementation.

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

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 device efficiently reduces noise leakage through the side surfaces of the machine room, ensuring effective cooling and increased efficiency of the compressor and condenser, regardless of rotation speed changes.

Implementation Method 1

a generator unit that outputs sound frequencies to cancel the noise

Methodology Applied
Scientific EffectSound wave interference: Interference

Implementation Method 2

a sensing unit to measure noise and a generator unit that outputs sound frequencies to cancel the noise

Methodology Applied
Scientific EffectSound detection: Sound

Implementation Method 3

two speaker units positioned to counteract horizontal vibrations

Methodology Applied
Scientific EffectVibration cancellation: Vibration

Data Source

PatentEP3842720B1refrigerator
Publication Date: 2026.04.15 LG ELECTRONICS INC
  • EP3842720B1 patent drawingFigure 1~2
  • EP3842720B1 patent drawingFigure 3~4
  • EP3842720B1 patent drawingFigure 5(a)~6

AI summary

A refrigerator with a noise reduction device is disclosed. The noise reduction device measures noise generated from a machine room of the refrigerator and outputs a sound signal having a frequency canceling the noise.