Compressor Bypass Valve Control to Prevent Refrigerant Oil Dilution
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Solution Overview
Problem
Air conditioners face the challenge of refrigerant oil dilution due to the inflow of a large amount of refrigerant from the accumulator into the compressor, especially after startup when the two-way valve is closed, leading to potential discharge of refrigerator oil.
Innovation Solution
The air conditioner employs a controller to manage the opening and closing of a two-way valve based on compressor temperature and pressure sensors, ensuring the valve is opened when the compressor temperature is below a certain threshold and closed when it reaches a predetermined temperature, thereby preventing refrigerant flow and maintaining optimal compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the two-way valve is closed after startup to prevent refrigerant discharge, then refrigerant discharge is prevented, but a large amount of refrigerant from the accumulator flows into the compressor causing oil dilution
Solution Approach 1:
The system performs preliminary heating of the compressor during startup before closing the two-way valve. By pre-heating the compressor to a predetermined temperature, the system ensures that when the two-way valve is subsequently closed, the compressor is already at a temperature that prevents refrigerant condensation and oil dilution, thus resolving the contradiction between preventing refrigerant discharge and avoiding oil dilution.
Solution Approach 2:
The control method implements periodic operation phases: first heating the compressor at a specific frequency for a predetermined time, then closing the two-way valve and maintaining operation. This periodic action pattern ensures the compressor reaches optimal temperature conditions before preventing refrigerant flow, thereby preventing both refrigerant discharge and oil dilution.
2Object-generated harmful factors
If the compressor operates at low frequency during startup to prevent refrigerant discharge, then refrigerant discharge is reduced, but the operation time is extended
Solution Approach 1:
The system uses periodic action by operating the compressor at a specific frequency for a predetermined time period during startup, then transitioning to normal operation. This time-limited periodic operation at controlled frequency prevents refrigerant discharge during the critical startup phase while minimizing the extended operation time through defined transition criteria.
Solution Approach 2:
The control method changes operational parameters (frequency and time) during startup. By setting specific frequency and time parameters for the startup phase, the system prevents refrigerant discharge while limiting the extended operation time. The parameters are adjusted based on compressor temperature conditions to optimize both protection and time efficiency.
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 control method effectively prevents refrigerant oil dilution and discharge by regulating the two-way valve's operation according to temperature conditions, ensuring efficient compressor performance and reducing the risk of oil discharge during refrigerant flow.
Implementation Method 1
a compressor 21 of a high-pressure and variable speed type
Implementation Method 2
the suction pipe 21b and the discharge pipe 21a are connected to each other by a bypass pipe 30, and the bypass pipe is opened or closed by the two-way valve 31
Implementation Method 3
an outdoor heat exchanger 23 that is connected to a discharge pipe 21a of the compressor 21
Implementation Method 4
a decompression device 24 that is connected to an outlet of the outdoor heat exchanger 23
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An air conditioner according to an embodiment of the invention includes a refrigerator cycle unit having a variable speed compressor 21, an outdoor heat exchanger 23, a decompression device 24, an indoor heat exchanger 51, and an accumulator 25 sequentially connected to one another, a bypass pipe 30 that connects the discharge side of the compressor 21 and an outlet of the accumulator 25 and has a two-way valve 31 in the middle thereof, a discharge temperature sensor 28 that detects the temperature of the compressor 21, and a controller 40 that opens or closes the two-way valve 31, and limits the number of rotations of the compressor 21 to a predetermined value or less, on the basis of the temperature detected by the discharge temperature sensor 28 when the compressor 21 starts.