Bimetal Switch Refrigerator Cooling for Low-Ambient Freezer Control
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Solution Overview
Problem
Mechanically controlled cooling devices struggle to maintain effective refrigeration in low ambient temperatures, leading to increased freezing compartment temperatures and potential thawing of stored foodstuffs due to thermostatic switches' inability to activate the compressor promptly.
Innovation Solution
A cooling device design incorporating a thermostatic switch near the fresh food compartment and a bimetal switch near the freezing compartment evaporator, connected in series with a heater, which activates the compressor by increasing temperature in the fresh food compartment when ambient temperatures are low, ensuring both compartments remain within optimal ranges without direct electronic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermostatic switch is used to control the compressor in low ambient temperatures, then the fresh food compartment temperature can be maintained, but the freezing compartment temperature increases and foodstuffs may thaw
Solution Approach 1:
The patent divides the temperature control function into two independent switches: a thermostatic switch for the fresh food compartment and a bimetal switch for the freezing compartment. Each switch independently controls its respective compartment, allowing the freezing compartment to be heated when needed without affecting the fresh food compartment temperature control.
Solution Approach 2:
The bimetal switch acts as an intermediary device that directly senses the freezing compartment temperature and controls the heating element. This intermediary switch enables precise control of the freezing compartment without relying on the thermostatic switch designed for the fresh food compartment.
2Temperature
If a heater is disposed near the thermostatic switch to raise its temperature, then the compressor can be activated, but energy consumption increases due to unnecessary heater operation
Solution Approach 1:
The bimetal switch is positioned to directly sense the freezing compartment temperature and automatically controls the heater operation based on actual need. When the freezing compartment temperature rises above the set point, the bimetal switch activates the heater; when it drops below, the switch deactivates the heater. This self-regulating mechanism eliminates unnecessary heater operation and reduces energy consumption.
Solution Approach 2:
The bimetal switch provides direct temperature feedback from the freezing compartment to control the heater. This feedback mechanism ensures the heater operates only when the freezing compartment temperature exceeds the desired range, optimizing energy usage while maintaining reliable temperature control.
3Measurement precision
If electronic control systems are used to detect freezing compartment temperature, then precise temperature control can be achieved, but production costs increase
Solution Approach 1:
The patent employs a bimetal switch, a simple and inexpensive mechanical device, instead of expensive electronic temperature sensors. The bimetal switch provides sufficient temperature detection capability for refrigerator operation without the high cost associated with electronic control systems, making the device more economical to manufacture while maintaining adequate performance.
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 solution effectively maintains refrigeration in low ambient temperatures by controlling the compressor and heater operation based on compartment temperatures, preventing thawing and freezing, while reducing energy consumption and production costs by using mechanical controls.
Implementation Method 1
the bimetal switch completes the circuit by elongating when its temperature reaches an upper limit temperature predetermined by the producer
Implementation Method 2
switches off the circuit when its temperature reaches a lower limit temperature predetermined by the producer
Implementation Method 3
The fresh food compartment temperature increases upon operation of the heater
Implementation Method 4
a compressor (4) that compresses and circulates the refrigerant fluid in the refrigeration cycle
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a mechanically controlled cooling device (1) wherein the refrigeration process is performed effectively, comprising a fresh food compartment (2) wherein foodstuffs are placed to be cooled, a freezing compartment (3) kept at lower temperatures than the fresh food compartment (2) wherein foodstuffs are placed to be frozen, a compressor (4) that compresses and circulates the refrigerant fluid in the refrigeration cycle, a fresh food compartment evaporator (5) that provides the interior of the fresh food compartment (2) to be cooled, a freezing compartment evaporator (6) that provides the interior of the freezing compartment (3) to be cooled, at least one heater (7) disposed on and/or in the vicinity of the fresh food compartment evaporator (5) and a thermostatic switch (8) disposed on and/or in the vicinity of the fresh food compartment evaporator (5), controlling the operation of the compressor (4) depending on the temperature value detected thereby, characterized by a bimetal switch (9) disposed on and/or in the vicinity of the freezing compartment evaporator (6), connected in series to the heater (7) and controlling the operation of the heater (7) depending on the temperature value detected thereby.