Air-conditioning device
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Solution Overview
Problem
In air conditioning apparatus using a four-way switching valve, there is a challenge in preventing the compressor from sucking in liquid refrigerant during the resumption of heating operation, especially when multi-hole flat tubes are used as heat transfer tubes in the outdoor heat exchanger, leading to potential compressor reliability issues due to refrigerant accumulation.
Innovation Solution
Implementing pressure equalization control by switching the four-way switching valve from the heating cycle state to the cooling cycle state and stopping the compressor, which prevents the flow of refrigerant into the outdoor heat exchanger, thereby reducing the likelihood of liquid refrigerant being pushed to the compressor's suction side, and optionally performing outdoor heat exchanger refrigerant discharge control to further reduce refrigerant accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the air conditioning apparatus uses multi-hole flat tubes as heat transfer tubes in the outdoor heat exchanger, then heat transfer efficiency is improved, but liquid refrigerant accumulates in the outdoor heat exchanger and is pushed to the compressor suction side during pressure equalization, compromising compressor reliability
Solution Approach 1:
The patent applies preliminary action by performing outdoor heat exchanger refrigerant discharge control before pressure equalization control. The system discharges refrigerant from the outdoor heat exchanger in advance by switching the four-way switching valve to the cooling cycle state and continuing compressor operation for a predetermined period, thereby removing liquid refrigerant that would otherwise be pushed to the compressor suction side during subsequent pressure equalization
Solution Approach 2:
The patent implements periodic action through sequential control operations: first performing outdoor heat exchanger refrigerant discharge control for a predetermined time period, then switching to pressure equalization control. This periodic sequence ensures that refrigerant is discharged at appropriate intervals to prevent compressor damage while maintaining system efficiency
2Stress or pressure
If the four-way switching valve is switched to the cooling cycle state during pressure equalization, then pressure equalization is achieved, but liquid refrigerant flows from the outdoor heat exchanger to the suction side of the compressor
Solution Approach 1:
The system performs preliminary refrigerant discharge by switching to the cooling cycle state and continuing compressor operation before pressure equalization begins. This preliminary action removes liquid refrigerant from the outdoor heat exchanger, preventing it from flowing to the compressor suction side when pressure equalization subsequently occurs
Solution Approach 2:
The patent uses the compressor's suction side as an intermediary pathway to discharge refrigerant from the outdoor heat exchanger before pressure equalization. By temporarily maintaining compressor operation in cooling cycle state, the system creates a controlled flow path that safely removes liquid refrigerant away from the outdoor heat exchanger
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 prevents the compressor from ingesting liquid refrigerant during heating operation resumption, reducing the risk of compressor failure and minimizing refrigerant accumulation in the accumulator, thus enhancing the apparatus's reliability and operational efficiency.
Implementation Method 1
a four-way switching valve (22) to switch between and perform a cooling operation and a heating operation
Implementation Method 2
a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23), an expansion valve (24), and an indoor heat exchanger (41) being interconnected
Implementation Method 3
an expansion valve (24)
Implementation Method 4
an outdoor heat exchanger (23) that uses multi-hole flat tubes (231) as heat transfer tubes (2310)
Implementation Method 5
an indoor heat exchanger (41)
Implementation Method 6
an accumulator (25) that temporarily accumulates the refrigerant sucked into the compressor (21)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An air conditioning apparatus (1) has a refrigerant circuit (10) in which a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23), an expansion valve (24), and an indoor heat exchanger (41) are interconnected. The outdoor heat exchanger (23) is a heat exchanger that uses multi-hole flat tubes as heat transfer tubes (231). When stopping a heating operation, the air conditioning apparatus (1) performs pressure equalization control that switches the four-way switching valve (22) from a heating cycle state to a cooling cycle state, stops the compressor (21), and equalizes the pressure in the refrigerant circuit (10).