Refrigeration appliance and method for initialising a defrosting operation in a refrigeration appliance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for initializing a defrosting process in refrigeration devices with speed-controlled compressors are unsatisfactory as they rely on estimating frost thickness based on compressor running time, which is unreliable due to varying compressor speeds, and do not account for frost formation rates accurately.
Innovation Solution
A method that involves setting an initial compressor speed, monitoring deviations from this speed to maintain a setpoint temperature, and initiating defrosting when a predetermined deviation limit is exceeded, with adjustments based on temperature differences and past deviations to ensure reliable frost thickness assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods use cumulative compressor runtime to estimate frost thickness, then the method is simple to implement, but the estimation becomes unreliable with variable-speed compressors
Solution Approach 1:
The invention changes the monitoring parameter from cumulative runtime to instantaneous speed deviation. Instead of tracking total compressor operation time, the system monitors how much the current speed n(t) deviates from the initial speed n0, and integrates this deviation over time. This parameter change makes the method reliable for variable-speed compressors because it directly captures the effect of speed variations on frost formation rate.
2Manufacturing precision
If compressor speed is continuously adjusted to maintain setpoint temperature, then temperature control precision is improved, but frost thickness assessment becomes more complex
Solution Approach 1:
The invention uses feedback by continuously monitoring the compressor speed deviation from its initial value and integrating this deviation. The control unit compares the current speed n(t) with the initial speed n0, calculates the deviation, and accumulates it over time. This feedback mechanism provides a reliable frost thickness indicator while working seamlessly with the continuous speed adjustment needed for precise temperature control.
3Adaptability or versatility
If defrosting is initiated based on weighted cumulative runtime, then some adaptation to variable speeds is achieved, but reliable estimation requires known and reproducible speed-frost formation relationship
Solution Approach 1:
The invention inverts the conventional approach by not trying to predict frost thickness from speed, but rather detecting frost thickness from the actual speed behavior. Instead of using a predetermined relationship between speed and frost formation, the system monitors how the compressor speed actually deviates from its initial value and uses this observed deviation as the direct indicator of frost thickness. This inversion eliminates the need for known and reproducible speed-frost relationships.
Data Source
Figure 1~3
AI summary
The invention relates to a method for initialising a defrosting operation in a refrigeration appliance having a speed-controlled compressor (5), which method comprises the steps of a) starting up (S10-S19; S21) the compressor (5) at a speed set to an initial value no, b) adjusting (S3, S5) the speed nt of the compressor (5) in order to prevent the temperature (Tin) in a storage chamber (3) of the refrigeration appliance from deviating from a target temperature, c) monitoring (S6) a deviation between the adjusted speed nt and the initial value no, and d) deciding (S7) that defrosting is necessary if the deviation exceeds a limit value.