Refrigerator Cooling Branch Pressure Control for Icing and Condensation

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Solution Overview

Problem

Refrigeration systems face issues with the cooling of heat sinks in motor control systems, leading to overheating, icing, or condensation, which can cause malfunctions and damage.

Innovation Solution

Setting the minimum evaporation temperature of the heat sink above the freezing point of water and using an evaporation pressure regulator to ensure the temperature remains above the dew point, with a minimal refrigerant flow during startup to prevent overheating and ensure quick temperature regulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the heat sink is cooled strongly in the control cooling branch, then the electronic power components are cooled effectively, but icing or condensation occurs on the heat sink causing malfunctions in motor control

Engineering Contradiction:
Improveheat sink temperatureVSAvoidmotor control reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies parameter changes by setting a minimum evaporation temperature for the refrigerant in the heat sink that is above the freezing point of water. This parameter adjustment prevents the heat sink temperature from dropping below freezing, thereby avoiding icing and condensation while still providing effective cooling for the electronic power components.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the evaporation pressure is reduced to increase cooling capacity, then the heat sink cooling efficiency improves, but the temperature falls below freezing point causing icing

Engineering Contradiction:
Improvecooling capacityVSAvoidevaporation temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent resolves this contradiction by changing the evaporation temperature parameter to a minimum value that is above the freezing point of water. This ensures that even when cooling capacity is increased, the temperature remains in a safe range that prevents icing, while still allowing effective heat dissipation from the electronic components.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If refrigerant flow is restricted during start-up phase, then temperature control is simplified, but the heat sink overheats before cooling begins

Engineering Contradiction:
Improvecontrol system complexityVSAvoidheat sink temperature
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent applies preliminary action by ensuring that the minimum evaporation temperature is set above freezing point before the start-up phase begins. This pre-established parameter setting prevents icing and condensation from occurring during the critical start-up period, even before the cooling system fully activates, thereby simplifying control while protecting the electronics.

Inventive Principle:
Principle #10Preliminary action

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

Prevents icing and condensation on the heat sink, ensuring reliable operation and extending the lifespan of electronic components by maintaining a stable temperature above freezing and dew points.

Implementation Method 1

a cooling element (40) in which a minimum evaporation temperature of the heat sink is above a freezing point temperature of water

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

a heat sink is arranged that is thermally connected to electronic power components of the motor control

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2828589B1Refrigerator
Publication Date: 2019.11.06 BITZER KUEHLMASCHINENBAU GMBH
  • EP2828589B1 patent drawingFigure 1
  • EP2828589B1 patent drawingFigure 2
  • EP2828589B1 patent drawingFigure 3

AI summary

In order to improve a refrigeration system, comprising a refrigeration cycle in which a refrigerant compressor, a condenser following the refrigerant compressor, an expansion device following the condenser and an evaporator following the expansion device are arranged, said evaporator being connected in return with the refrigerant compressor, wherein the refrigerant compressor has a variable speed drive motor controlled by an electronic motor control unit and a control cooling branch through which refrigerant flows and which branches off from the refrigerant cycle between the condenser and the expansion device and which is guided to a connection of the refrigerant compressor and in which a heat sink that is thermally conductively connected to electronic power components of the motor control unit is arranged, in such a manner that malfunctions in the motor control unit are avoided to the greatest possible extent, a regulating system for the control cooling branch is provided which, during operation of the refrigerant compressor, regulates a temperature of the heat sink such that a minimum evaporation temperature of the heat sink lies above a freezing point temperature and below a condensation temperature of the refrigerant in the condenser.