Refrigerator Compressor Startup Delay for High-Pressure Relief

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Solution Overview

Problem

Existing refrigeration devices face inefficiencies and reliability issues, particularly during startup under critical conditions such as high ambient temperatures and low power supply, due to premature refrigerant recondensation and high compressor starting pressures.

Innovation Solution

Incorporating a control unit with a delay mechanism that delays the compressor startup by a time delay after the valve opens, allowing refrigerant to flow into the evaporator and reducing pressure, thereby easing compressor startup and preventing recondensation, which is adjustable based on voltage and temperature conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the compressor is started immediately after the valve opens, then the response time is short, but the compressor starting pressure is high and recondensation occurs

Engineering Contradiction:
Improvecompressor starting reliabilityVSAvoidcompressor startup delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The valve is opened before the compressor starts running, allowing refrigerant to flow into the evaporator and reducing pressure in advance. This preliminary action reduces the starting pressure burden on the compressor motor, enabling reliable startup even under critical conditions like high ambient temperatures and low power supply voltage.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The valve opening before compressor startup prevents warm refrigerant from flowing back into the evaporator and causing recondensation. By establishing unidirectional flow in advance, the system prevents the harmful effect of recondensation that would otherwise occur when the compressor stops and hot refrigerant reverses flow.

Inventive Principle:
Principle #9Preliminary anti-action

2Reliability

If the compressor motor is oversized to handle high starting pressure, then starting reliability improves, but energy consumption and cost increase

Engineering Contradiction:
Improvecompressor startup reliabilityVSAvoidcompressor motor energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

By opening the valve before compressor startup, the system reduces the pressure differential that the motor must overcome during startup. This allows the use of a smaller, more energy-efficient motor while maintaining reliable startup performance, as the preliminary pressure reduction eliminates the need for excessive starting torque.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the valve opens immediately when compressor stops, then refrigerant flow control is responsive, but recondensation into evaporator occurs

Engineering Contradiction:
Improverefrigerant flow control efficiencyVSAvoidrecondensation of refrigerant
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The valve is opened before the compressor stops running, establishing a pressure differential that prevents warm refrigerant from flowing back into the evaporator. This preliminary anti-action counteracts the potential harmful effect of recondensation before it can occur, maintaining refrigerant flow control efficiency while preventing evaporator heating.

Inventive Principle:
Principle #9Preliminary anti-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

This solution enhances the refrigeration device's efficiency, reduces energy consumption, and allows for a smaller, more energy-efficient electric motor, ensuring reliable operation even under adverse conditions while minimizing manufacturing and operational costs.

Implementation Method 1

allowing refrigerant to flow into the evaporator and reducing pressure, thereby easing compressor startup

Methodology Applied
Scientific EffectPressure reduction through refrigerant flow: Pressure Gradient

Implementation Method 2

an evaporator with an evaporator inlet and an evaporator outlet... for compressing or evaporating a coolant

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a compressor with a compressor inlet and a compressor outlet... for compressing or evaporating a coolant

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2211128B1Method for operating a refrigerator and a refrigerator
Publication Date: 2014.12.10 BSH HAUSGERATE GMBH
  • EP2211128B1 patent drawingFigure 1~2

AI summary

The device (1) has a compressor (2) with a compressor inlet and a compressor outlet, and an evaporator with an evaporator inlet and an evaporator outlet. A valve (4) is arranged in a coolant circuit between the compressor outlet and the evaporator inlet. The compressor and the valve are controlled by a control unit (6). The control unit has a delay unit (8), which causes the compressor to be activated with a time delay after opening the valve. A temperature sensor is provided for measuring the instantaneous surrounding temperature of the cooling device. An independent claim is also included for a method for operating the cooling device.