Multi-split air conditioning system and control method therefor
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Solution Overview
Problem
In multi-split air conditioning systems, frequent oil return by the compressor can cause dewing and dripping at indoor units in an off state due to inadequate oil return control methods, affecting user experience.
Innovation Solution
A control method that determines whether an indoor unit in an off state is at risk of dewing and adjusts the operation of the fan and electronic expansion valve accordingly during oil return, either maintaining the fan off or operating it at a low speed to prevent dewing and dripping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electronic expansion valve of the indoor unit in off state is opened to return refrigeration oil to the outdoor unit, then the compressor can be effectively lubricated and cooled, but the indoor unit may experience dewing and dripping affecting user comfort
Solution Approach 1:
The patent changes the operational parameters of the fan during oil return by controlling it to run at a specific speed (e.g., 300-600 rpm) rather than being completely off or at full speed. This parameter adjustment allows the fan to generate sufficient airflow to prevent dewing on the heat exchanger surface while not being so strong as to blow dew water outward, thus resolving the contradiction between enabling oil return and preventing dewing-related harm.
Solution Approach 2:
The patent implements dynamic control of the fan based on the oil return state. The fan speed is adjusted according to whether oil return is needed and the operational state of the indoor unit. This dynamic adjustment allows the system to adapt fan operation to the specific condition, enabling effective oil return when needed while preventing dewing harm during the process.
2Productivity
If the fan of the indoor unit is operated at high speed during oil return, then refrigerant evaporation is enhanced, but dewing and dripping occurs affecting user experience
Solution Approach 1:
The patent optimizes the fan speed parameter to a specific range (300-600 rpm) that balances two opposing requirements: generating enough airflow to promote refrigerant evaporation and prevent dewing, while avoiding excessive speed that would blow dew water outward and affect user comfort. This precise parameter control resolves the contradiction between evaporation efficiency and dewing prevention.
Solution Approach 2:
Instead of using full fan speed for oil return, the patent applies partial action by controlling the fan to run at a moderate speed (300-600 rpm) that is sufficient for the oil return condition but not excessive. This partial operation achieves the necessary refrigerant evaporation and dewing prevention without causing the harmful effect of blowing dew water outward.
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 method effectively reduces the occurrence of dewing and dripping at indoor units, enhancing user comfort by ensuring proper refrigerant evaporation and oil return management.
Implementation Method 1
controlling the fan of the indoor unit according to a determination result
Implementation Method 2
ensuring proper refrigerant evaporation
Data Source
AI summary
The present disclosure discloses a control method for a multi-split air conditioning system and a multi-split air-conditioning system, the multi-split air conditioning system, including a compressor and a plurality of indoor units respectively arranged on a plurality of parallel branches, the indoor unit including a fan and the control method including: in a cooling mode, when the multi-split air conditioning system needs oil return, the multi-split air conditioning system opening a branch where an indoor unit in an off state is located, determining whether the indoor unit has reached a dewing condition, opening the branch on which the indoor unit is located, and controlling the fan of the indoor unit according to a determination result.