Refrigerant Charging Control for Multi-Indoor Air Conditioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In air conditioning apparatuses with multiple indoor units connected via liquid and gas refrigerant communication pipes, determining the correct refrigerant charge is challenging, especially at low outdoor temperatures, as the ease of refrigerant accumulation varies among indoor units, leading to potential overcharging or undercharging of the refrigerant circuit.
Innovation Solution
The air conditioning apparatus performs a combination of heating and cooling refrigerant charging operations, with the control component first completing the heating refrigerant charging operation to prevent indoor temperature drops and then switching to cooling to ensure the correct refrigerant quantity is reached, using conditions such as refrigerant state, subcooling, and temperature differences to determine charging completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the determination of refrigerant charging completion is performed on the basis of state quantities of all indoor heat exchangers functioning as radiators, then the refrigerant charging operation can be completed, but the refrigerant circuit becomes overcharged because refrigerant accumulates excessively in indoor heat exchangers where it accumulates easily
Solution Approach 1:
The patent extracts the determination of refrigerant charging completion from the set of all indoor heat exchangers and focuses it on a specific one (the first indoor heat exchanger). This extraction resolves the contradiction by preventing overcharging that occurs when monitoring all heat exchangers, while still ensuring adequate charging by selecting an appropriate heat exchanger for monitoring
Solution Approach 2:
The patent applies local quality by treating different indoor heat exchangers differently in the determination process. Instead of uniformly monitoring all heat exchangers, it selectively focuses on one specific heat exchanger (the first one) whose refrigerant accumulation characteristics are representative, thereby achieving precise charging control without overcharging other heat exchangers
2Productivity
If the determination of refrigerant charging completion is performed on the basis of state quantities of some indoor heat exchangers, then the refrigerant charging operation can be completed efficiently, but the refrigerant circuit becomes undercharged because insufficient refrigerant accumulates in indoor heat exchangers where it accumulates with difficulty
Solution Approach 1:
The patent applies self-service by utilizing the natural refrigerant accumulation characteristics of the first indoor heat exchanger during heating operation. The system allows refrigerant to accumulate naturally in this heat exchanger without active intervention, and uses this natural accumulation state as the basis for determining charging completion, thereby achieving both efficiency and adequate charging quantity
Solution Approach 2:
The patent performs preliminary action by conducting heating refrigerant charging operation first, which allows refrigerant to naturally accumulate in the first indoor heat exchanger before switching to cooling operation. This preliminary heating phase ensures that the refrigerant distribution reaches a state that reflects the actual accumulation characteristics, enabling accurate determination of charging completion
3Loss of time
If the cooling refrigerant charging operation is performed directly without heating operation, then the refrigerant charging operation can be completed quickly, but the indoor temperature drops excessively
Solution Approach 1:
The patent applies preliminary action by performing heating refrigerant charging operation before cooling refrigerant charging operation. This preliminary heating phase serves two purposes: it prevents excessive indoor temperature drops during charging, and it allows refrigerant to naturally accumulate in the first indoor heat exchanger, creating accurate conditions for determining charging completion
Solution Approach 2:
The patent applies periodic action by dividing the refrigerant charging process into distinct phases: first heating refrigerant charging operation, then cooling refrigerant charging operation. This periodic structure allows the system to alternate between heating and cooling modes, achieving both temperature maintenance and efficient charging completion determination
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 approach allows for appropriate refrigerant charging without excessively lowering indoor temperatures and ensures the refrigerant circuit is accurately charged, even at low outdoor temperatures, by accounting for differences in refrigerant accumulation ease among indoor units.
Implementation Method 1
an outdoor unit having an outdoor heat exchanger and plural indoor units having indoor heat exchangers being interconnected via a liquid refrigerant communication pipe and a gas refrigerant communication pipe
Implementation Method 2
a vapor compression refrigerant circuit configured as a result of the outdoor unit and the plural indoor units being interconnected via the liquid refrigerant communication pipe and the gas refrigerant communication pipe
Data Source
Figure 1
Figure 2
Figure 3
AI summary
When charging a refrigerant circuit (10) with refrigerant, a control component (8) starts a heating refrigerant charging operation that is performed by switching the refrigerant circuit (10) to a heating cycle state and performs the heating refrigerant charging operation until a predetermined heating refrigerant charging completion condition is met. Thereafter, the control component (8) switches to a cooling refrigerant charging operation that is performed by switching the refrigerant circuit (10) to a cooling cycle state and performs the cooling refrigerant charging operation until a refrigerant charging completion condition where the refrigerant circuit (10) is charged with a prescribed quantity of the refrigerant is met.