Indoor Unit Valve Control to Prevent Refrigerant Buildup Noise
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Solution Overview
Problem
In multi-type air conditioners, refrigerant accumulation in inactive indoor units can lead to increased costs and safety risks, especially with flammable refrigerants, and can cause users to mistakenly believe the system has failed due to noise during operation cessation.
Innovation Solution
The air conditioner incorporates on-off valves and expansion valves upstream of indoor heat exchangers, controlled by a unit that equalizes pressure and operates fans to prevent refrigerant accumulation and noise during unit shutdown, allowing for seamless operation and user reassurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerant circuit is charged with a higher amount of refrigerant to ensure sufficient refrigerant circulation for all indoor units operating simultaneously, then the air conditioning capabilities can be maintained, but the cost increases
Solution Approach 1:
The refrigerant circuit is segmented into multiple independent zones, each served by a separate compressor. This allows each compressor to serve a specific group of indoor units, reducing the total refrigerant charge needed in the overall system while ensuring sufficient refrigerant circulation for simultaneous operation of all indoor units across different zones
Solution Approach 2:
The system transitions from a single centralized refrigerant circulation system to a multi-dimensional distributed architecture with multiple compressors serving different zones. This dimensional change from centralized to distributed architecture reduces refrigerant accumulation risks and lowers total refrigerant charge requirements
2Reliability
If the refrigerant circuit is charged with a higher amount of refrigerant to ensure sufficient refrigerant circulation for all indoor units operating simultaneously, then the air conditioning capabilities can be maintained, but the safety risk increases due to potential refrigerant leakage and fire hazard
Solution Approach 1:
The refrigerant circuit is divided into multiple independent zones, each with its own compressor and refrigerant circulation system. This segmentation limits the potential spread of refrigerant leakage to a single zone, reducing the overall safety risk and fire hazard associated with high refrigerant charges in the entire system
Solution Approach 2:
The system architecture changes from a single centralized refrigerant system to a multi-dimensional distributed system, where refrigerant is contained in smaller isolated volumes across multiple zones. This dimensional transformation reduces the consequences of potential refrigerant leakage and fire hazards
3Reliability
If the on-off valve corresponding to the stopping indoor unit is closed to prevent refrigerant accumulation, then refrigerant accumulation is prevented, but noise of refrigerant occurs when operation stops causing user confusion
Solution Approach 1:
The refrigerant flow control is segmented into multiple stages: the on-off valve closes to prevent accumulation, while the expansion valve remains open to allow gradual pressure equalization. This segmented control approach prevents both refrigerant accumulation and abrupt noise generation
Solution Approach 2:
The expansion valve is kept open in advance before the on-off valve closes, preparing the refrigerant path for smooth pressure equalization. This preliminary action prevents sudden pressure changes and associated noise when the on-off valve shuts off refrigerant flow
4Reliability
If the expansion valve is closed to prevent refrigerant accumulation in the stopping indoor unit, then refrigerant accumulation is prevented, but the indoor fan cannot effectively discharge accumulated refrigerant
Solution Approach 1:
Instead of closing the expansion valve to prevent refrigerant accumulation, the invention inverts the approach by keeping the expansion valve open and using the on-off valve for flow control. The indoor fan continues operating to discharge refrigerant through the open expansion valve, simultaneously achieving accumulation prevention and effective refrigerant discharge
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 refrigerant accumulation in stopped indoor units, reducing costs and user confusion, while ensuring safe and efficient operation of the air conditioning system.
Implementation Method 1
driving an indoor fan in the stopping unit until pressure in a part between an on-off valve that corresponds to the stopping unit and an expansion valve and pressure in a part downstream of the expansion valve are equalized
Implementation Method 2
fully opening the expansion valve that corresponds to the stopping unit
Data Source
Figure 1A
Figure 1B
Figure 2~3
AI summary
An air conditioner (1) includes an outdoor unit (2), a plurality of indoor units (5a to 5d), a plurality of expansion valves (24a to 24d) which correspond to the indoor units and are provided upstream of indoor heat exchangers (51a to 51d), a plurality of on-off valves (7a to 7d) which are provided upstream of the expansion valves, and control unit (200 and 500a) configured to selectively control individual components in the air conditioner. When the indoor units include the second indoor unit (5b) currently operating, and when a stopping of the first indoor unit (5a) instructed to stop operating is due to thermostat-off operation, the control unit performs a procedure to stop the first indoor unit (5a), the procedure including closing a first on-off valve (7a) and driving a first indoor fan (55a) until pressure in a part between the first on-off valve (7a) and the first expansion valve (24a) and pressure in a part downstream of the first expansion valve (24a) are equalized, fully opening the first expansion valve (24a), and stopping the first indoor fan (55a) .