Single-Door Refrigerator Compressor Control for Low-Ambient Freezing
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Solution Overview
Problem
Low-cost single-door refrigerators face challenges in maintaining proper freezer compartment performance at low ambient temperatures without increasing energy consumption, as existing solutions require additional heaters and sensors, leading to higher costs and inefficiencies.
Innovation Solution
A control method that eliminates the heater element by using a microprocessor to control compressor insertion time based on ambient temperature and compartment temperatures, switching between control patterns to optimize compressor activation and reduce energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heater element is added to maintain freezer performance at low ambient temperatures, then the reliability of the freezer compartment is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the heater element from the system entirely. Instead of adding a heating component to maintain freezer performance at low ambient temperatures, the solution extracts this unnecessary component and replaces it with a control algorithm that manages compressor operation based on ambient temperature detection, thereby simplifying the device while maintaining reliability
Solution Approach 2:
The patent replaces the mechanical/thermal solution (heater element) with an electronic control solution. A microprocessor-based control unit monitors ambient temperature and adjusts compressor insertion time accordingly, substituting a passive thermal component with an active electronic control system that achieves the same reliability goal without additional heating hardware
2Reliability
If a heater element is added to maintain freezer performance at low ambient temperatures, then the reliability of the freezer compartment is improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes the heater element from the system entirely. Instead of adding a heating component to maintain freezer performance at low ambient temperatures, the solution extracts this unnecessary component and replaces it with a control algorithm that manages compressor operation based on ambient temperature detection, thereby simplifying the device while maintaining reliability
Solution Approach 2:
The patent uses the existing compressor and control unit, which are already present in the refrigerator, to perform the additional function of maintaining freezer performance. By repurposing existing components through software control rather than adding expensive dedicated heating components, the solution reduces manufacturing costs while achieving the same reliability outcome
3Temperature
If the heater is activated at low ambient temperature, then the temperature in the freezer compartment is maintained, but the energy consumption increases
Solution Approach 1:
The patent implements dynamic control of the compressor based on ambient temperature conditions. The control unit continuously monitors ambient temperature and adjusts the compressor insertion time accordingly, creating a dynamic system that adapts to changing environmental conditions rather than using a static heater element that operates continuously at low temperatures
Solution Approach 2:
The patent uses periodic compressor cycles with variable insertion times instead of continuous heater operation. The control unit manages periodic compressor activation, adjusting the duration and frequency of compression cycles based on ambient temperature, which is more energy-efficient than continuous heating while maintaining the required freezer temperature
4Measurement precision
If additional temperature sensors and wiring are added, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent makes the existing control unit multi-functional by programming it to perform both the original temperature control functions and the new ambient temperature monitoring function. The existing control unit, already present for managing compressor operation, is enhanced with additional algorithms to detect ambient temperature and adjust compression cycles accordingly, eliminating the need for separate dedicated sensors and control circuits
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 maintains desired temperature ranges in both compartments with reduced compressor running time and energy consumption, achieving higher efficiency and cost-effectiveness compared to traditional systems.
Implementation Method 1
An evaporator E is fixed to both the cavities
Implementation Method 2
a refrigerating circuit with compressor, evaporator, condenser
Implementation Method 3
a refrigerating circuit with compressor, evaporator, condenser
Data Source
Figure 1~3
AI summary
A mono-door refrigerator (10) comprises a fresh food compartment (12) with a temperature sensor and a freezer compartment (14), a refrigerating circuit with compressor, evaporator, condenser and a control circuit connected to the temperature sensor and to the compressor. The control unit is adapted to assess the time elapsed from the last activation of the compressor and to compare this value to a threshold value, and to switch on the compressor if the assessed value is higher than the threshold.