Refrigerator Defrost Control Using Air Flow Sensor Frost Detection
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Solution Overview
Problem
Existing refrigerator systems face inefficiencies in determining the optimal time for defrosting due to reliance on cumulative compressor operation time and external temperature, without considering frost generation amounts, leading to inaccurate defrosting cycles and increased power consumption.
Innovation Solution
A control method that detects residual frost on the evaporator using temperature differences between on and off states of a heat generating element, determining the need for defrosting based on these parameters and adjusting the next defrost operation time accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the defrosting cycle is determined using cumulative compressor operation time and external temperature, then the defrosting operation can be performed periodically, but the accuracy of determining the actual frost generation amount is poor
Solution Approach 1:
The patent introduces a bypass passage as an intermediary element that allows air to flow around the evaporator. A sensor placed in this bypass passage indirectly measures frost accumulation by detecting changes in air flow characteristics, rather than directly measuring frost on the evaporator surface. This intermediary approach enables accurate frost detection without requiring complex direct measurement systems.
Solution Approach 2:
The patent replaces complex mechanical or direct sensing methods with a simpler air flow-based detection system. By using a sensor in the bypass passage to detect air flow changes caused by frost accumulation, the system substitutes a straightforward air flow measurement approach for more complex direct frost measurement techniques.
2Reliability
If defrosting is performed frequently to ensure complete frost removal, then cooling performance is maintained, but power consumption increases
Solution Approach 1:
The patent implements a feedback mechanism where the sensor continuously monitors air flow changes in the bypass passage, providing real-time information about frost accumulation. The controller uses this feedback to determine the optimal defrosting moment, initiating defrosting only when actual frost levels warrant it, rather than following a fixed schedule. This feedback-driven approach balances cooling performance with energy efficiency.
Solution Approach 2:
The patent transitions from a static, fixed-cycle defrosting schedule to a dynamic defrosting system that adapts to actual operating conditions. The defrosting cycle frequency and timing are adjusted dynamically based on real-time sensor readings of air flow changes, allowing the system to respond flexibly to varying frost accumulation rates and environmental conditions.
3Use of energy by moving object
If defrosting is delayed to reduce power consumption, then energy efficiency improves, but cooling performance deteriorates due to excessive frost
Solution Approach 1:
The continuous feedback from the bypass passage sensor allows the system to monitor frost accumulation in real-time, enabling delayed defrosting only when sensor readings indicate low frost levels. This feedback mechanism ensures defrosting is postponed safely without compromising cooling performance.
Solution Approach 2:
The sensor in the bypass passage provides advance warning of frost accumulation trends, allowing the system to plan defrosting operations optimally. By detecting air flow changes before they significantly impact cooling performance, the system can schedule defrosting at the most efficient moment, balancing energy savings with performance maintenance.
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 accurate determination of defrosting requirements, reducing power consumption and maintaining cooling performance by ensuring precise timing of defrosting operations based on actual frost amounts.
Implementation Method 1
the sensor includes a heat generating element and a sensing element... detection temperatures of the heat generating element
Implementation Method 2
the sensing element detects a temperature of the heat generating element... first detection temperature (Ht1) that is a lowest value and a second detection temperature (Ht2) that is a highest value
Data Source
AI summary
A method for controlling a refrigerator includes operating, for a set duration, a heating element of a sensor which responds to changes in air flow; sensing the temperature of the heating element in on or off state; and sensing residual frost on an evaporator on the basis of the difference in value of the temperature between a first sensed temperature, which is the lowest value, and a second sensed temperature, which is the highest value, from among the sensed temperatures of the heating element.