Refrigerator Bypass Sensor Design for Accurate Defrosting Control
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Solution Overview
Problem
Existing refrigerator systems struggle to accurately determine the time point for defrosting based on frost generation, leading to inefficient cooling performance and increased power consumption due to either delayed or unnecessary defrosting cycles.
Innovation Solution
A refrigerator design that includes a bypass passage with a sensor to detect changes in air flow rate, using a heat-generating element and temperature-sensing element to determine when defrosting is required, and a controller to operate the defroster accordingly, while minimizing frost generation around the sensor and preventing liquid introduction into the bypass passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If defrosting cycle is determined using cumulative operation time of compressor and external temperature, then defrosting can be performed periodically, but the defrosting timing is inaccurate because frost generation amount is not reflected
Solution Approach 1:
The patent introduces a feedback mechanism by using a sensor to detect air flow rate changes in the bypass passage, which directly reflects the actual frost generation amount on the evaporator. This feedback loop allows the defrosting control to be based on real-time conditions rather than predetermined schedules, resolving the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The patent replaces the mechanical/time-based defrosting control system with a sensor-based detection system. Instead of relying on cumulative operation time counters and temperature sensors, the system uses air flow rate detection to indirectly measure frost accumulation, achieving more precise defrosting timing without complex mechanical adjustments.
2Device complexity
If defrosting is performed based on fixed time intervals, then control is simple, but cooling performance deteriorates when defrosting is delayed or unnecessary
Solution Approach 1:
The system enables self-service defrosting control by automatically detecting frost accumulation through air flow rate changes and triggering defrosting only when necessary. This eliminates the need for complex manual scheduling while ensuring cooling performance is maintained by performing defrosting based on actual conditions rather than fixed intervals.
Solution Approach 2:
The patent changes the control parameter from fixed time intervals to dynamic air flow rate detection. By monitoring the air flow rate through the bypass passage, the system adapts the defrosting timing to actual frost generation conditions, maintaining simple control logic while significantly improving cooling performance reliability.
3Measurement precision
If sensor is placed in bypass passage to detect air flow rate, then defrosting timing is accurately determined, but frost may form around the sensor
Solution Approach 1:
The patent extracts the sensor from the main evaporator area and places it in a separate bypass passage. This separation allows the sensor to detect air flow rate changes that indicate frost formation on the evaporator without being directly exposed to the same extreme conditions that cause frost accumulation, thereby maintaining measurement precision while reducing frost formation around the sensor.
4Measurement precision
If bypass passage is used for sensing, then frost generation amount can be detected, but liquid may be introduced into the bypass passage
Solution Approach 1:
The patent segments the air flow path into a main passage through the evaporator and a separate bypass passage containing the sensor. This segmentation allows the sensor to monitor air flow conditions without being directly exposed to liquids that may accumulate in the main evaporator area, enabling accurate frost detection while preventing liquid contamination of the sensing system.
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 the defrosting time point, improving cooling efficiency and reducing power consumption by ensuring defrosting occurs only when necessary, while maintaining sensor accuracy and preventing frost formation.
Implementation Method 1
a heat generating element installed on the sensor PCB to generate heat when current is applied
Implementation Method 2
a temperature element configured to sense a temperature of the heat generating element
Implementation Method 3
Air in the storage space is cooled while flowing to a space, in which the evaporator is disposed, so as to be heat-exchanged with the evaporator
Implementation Method 4
a defroster configured to remove frost generated on a surface of the evaporator
Data Source
AI summary
A refrigerator of the present invention comprises: an inner case forming a storage compartment; a cold air duct guiding the flow of air within the storage compartment and forming a heat exchange space with the inner case; an evaporator disposed in the heat exchange space between the inner case and the cold air duct; a bypass passage disposed in the cold air duct so as to allow the flow of air to bypass the evaporator; a sensor disposed in the bypass flow channel and comprising a sensor housing, a sensor PCB received in the sensor housing, a heating element installed on the sensor PCB so as to generate heat when an electric current is applied thereto, a temperature element for sensing the temperature of the heating element, and a molding material with which the sensor housing is filled; a drfrosting means for removing frost formed on the surface of the evaporator; and a control unit for controlling the defrosting means on the basis of the value output from the sensor.