Multi-Unit Refrigerating Cycle Oil Balancing Without Inter-Unit Piping
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Solution Overview
Problem
Refrigerating cycle apparatuses with multiple outdoor units face oil imbalance issues due to complex connections and potential oil leakage or clogging, leading to insufficient lubrication for compressors, which can cause damage and reduce service life.
Innovation Solution
A refrigerating cycle apparatus with built-in oil balancing circuits in each outdoor unit, utilizing electronic valves to periodically and sequentially manage excess oil between compressors, eliminating the need for interunit oil balancing pipes, thus preventing oil leakage and clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil balancing tubes are connected between compressors to balance oil levels, then oil balancing is improved, but device complexity increases and oil leakage risk increases
Solution Approach 1:
The invention extracts the oil balancing function from the complex inter-unit piping system and relocates it to individual self-contained balancing circuits within each outdoor unit. This separates the oil balancing function from the refrigerant circulation system, eliminating the need for complex inter-unit oil balancing connections while maintaining reliable oil level control across all compressors
Solution Approach 2:
The invention segments the oil balancing system into independent circuits for each outdoor unit, with each unit managing its own oil levels through dedicated balancing circuits. This segmentation eliminates the need for interconnected oil balancing pipes between units, reducing overall system complexity and leakage risk points
2Reliability
If inter-unit oil balancing pipes are installed, then oil balancing between units is improved, but oil leakage and pipe clogging risks increase
Solution Approach 1:
The invention extracts the oil balancing function from the inter-unit piping system and relocates it to individual self-contained balancing circuits within each outdoor unit. This separates the oil balancing function from the refrigerant circulation system, eliminating the need for complex inter-unit oil balancing connections while maintaining reliable oil level control across all compressors
Solution Approach 2:
The invention prevents oil leakage and clogging by designing a system where oil balancing occurs within sealed indoor units through the refrigerant circulation system, rather than through exposed inter-unit piping. The preliminary design eliminates the vulnerability points where leakage and clogging would occur
3Measurement precision
If temperature detection in oil balancing tubes is used to detect oil levels, then oil level detection is improved, but device complexity and cost increase
Solution Approach 1:
The invention enables the refrigerant and oil mixture to self-indicate oil levels through temperature detection at existing system points, eliminating the need for separate detection devices. The system uses the natural thermal properties of the refrigerant-oil mixture to provide oil level information that can be read from the refrigerant temperature
Data Source
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AI summary
A refrigerating cycle apparatus (1) is equipped with a plurality of outdoor units (2a, 2b), each of which includes at least one high-pressure type compressor (4) with refrigerant and lubricating oil (L) stored therein. A discharge pipe (9) of the respective compressor is connected to a main discharge pipe (9) for jointly discharging refrigerant and oil to the indoor unit (3). A suction pipes (20) of the respective compressors is connected for returning the refrigerant and the oil from the indoor unit to the compressor. Each outdoor unit comprises a first oil balancing circuit (22, 23, 26, V1, 30) connected between a side surface of the casing of the respective compressor and the main discharge pipe (9) for allowing a flowing-in of the exceeding oil from the casing of the compressor. In another embodiment, each outdoor unit may include a second oil balancing circuit connected between a side surface of the casing of the respective compressor and the main suction pipe. The first and second balancing circuits may be periodically and sequentially controlled by oil solenoid valves. Therefore, oil balancing between the compressors of the plurality of outdoor units can be realized more efficiently.