Control method and system for refrigeration, oil return and noise reduction of multi-split air-conditioner
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Solution Overview
Problem
Existing multi-split air conditioners fail to effectively reduce noise during oil-return operations, particularly in cooling mode, due to refrigerant throttling sounds from standby indoor units, which disturb users.
Innovation Solution
A control method and system that adjusts the opening degree of electronic expansion valves in standby indoor units based on the load of switch-on units and presence of people in the room, using a human sensor module to determine occupancy, and controls the compressor frequency to minimize noise during oil-return operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electronic expansion valve of standby indoor units is opened during oil-return operation, then the oil return effect is improved, but the refrigerant throttling sound increases and disturbs users
Solution Approach 1:
The patent applies local quality by differentiating the opening degree of electronic expansion valves based on the presence of people in the room. When people are detected, the valve opens at a first (lower) degree to minimize noise; when no people are present, it opens at a second (higher) degree to maximize oil return effect. This localized adaptation resolves the contradiction between oil return effectiveness and noise reduction.
Solution Approach 2:
The patent implements dynamics by making the opening degree of the electronic expansion valve adjustable and variable based on real-time detection of human presence. The system dynamically switches between different opening degrees (first degree when people are present, second degree when absent) to adapt to changing conditions, thereby balancing oil return performance with noise control.
2Productivity
If the opening degree of electronic expansion valve is increased for better oil return, then the oil return efficiency is improved, but the noise disturbance to users increases
Solution Approach 1:
The patent applies parameter changes by modifying the opening degree parameter of the electronic expansion valve based on the detection result. The system changes the valve opening parameter between two distinct states (first opening degree and second opening degree) according to whether people are present in the room, thereby optimizing the balance between oil return efficiency and noise control.
Solution Approach 2:
The patent applies local quality by making the opening degree parameter dependent on the local condition of human presence. Different opening degrees are applied in different local contexts (rooms with people vs. rooms without people), allowing the system to optimize oil return efficiency in each local context while minimizing noise disturbance where users are present.
3Loss of time
If the oil-return operation interval is shortened, then the noise reduction frequency is increased, but the control complexity increases
Solution Approach 1:
The patent applies periodic action by implementing a timer that periodically checks whether the oil-return operation interval has been reached. This periodic detection mechanism automatically triggers the noise reduction mode at appropriate intervals, simplifying the control logic while achieving frequent noise reduction without requiring complex continuous monitoring or calculation systems.
Data Source
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AI summary
A control method and system for refrigeration, oil return and noise reduction of a multi-split air-conditioner. The method comprises: when the accumulative time that the frequency of a compressor is smaller than the set frequency threshold reaches the oil return cycle and a standby indoor unit exists, conducting an oil return running mode; resetting the accumulative time; starting counting the oil return running time; calculating the indoor unit starting load; determining the opening degree of an expansion valve of the standby indoor unit according to the indoor unit starting load and whether there is anyone in a room where the standby indoor unit is located; controlling the compressor to run according to the set oil return frequency; and when the oil return running time reaches the oil return set time, exiting the oil return running mode, and conducting a normal refrigerating running mode. By means of the control method, the oil return effect is ensured, and the influences of throttling sounds caused by opening of the expansion valve of the standby indoor unit on users during oil return are also reduced.