Frequency-conversion multi-online system and control method of lubricating oil of compressor thereof

Abstract

The invention discloses a frequency-conversion multi-online system and a control method of lubricating oil of a compressor thereof. The control method comprises the following steps of: carrying out oil path control according to a working frequency of a frequency-conversion compressor and an operation state of a constant-frequency compressor; and judging whether oil return operation is needed or not, and starting to return the oil when the oil return operation is needed simultaneously. According to the control method provided by the invention, the corresponding oil path control is carried out according to operation states of the frequency-conversion compressor and the constant-frequency compressor in the frequency-conversion multi-online system, so that an oil amount in the compressors can be ensured to be sufficient, and no phenomena of oil shortage or non-uniform oil distribution of the compressors exist. Furthermore, the oil path control is carried out, and whether the oil return operation is needed or not is judged simultaneously, and oil return treatment is started in time in the need of the oil return operation, so that the oil return has no need of being carried out at a fixed period in an operation process of the entire machine. Moreover, the oil return treatment is started in the need of the oil return, so as to realize intelligent oil return.

Description

technical field [0001] The invention relates to the technical field of air conditioning, in particular to a frequency conversion multi-connection system and a control method for lubricating oil of a compressor thereof. Background technique [0002] Frequency conversion multi-line is called "VRV (Varied Refrigerant Volume)" or "VRF (Variable Refrigerant Fluid)" in the industry, and it only entered the Chinese market in the 1990s. Due to the wide range of applications of this type of product, the market demand is increasing year by year. Moreover, the frequency conversion multi-line has been imported from the initial complete machine to the current domestic production, from the initial AC frequency conversion to the current DC frequency conversion, especially the core component compressors are also localized, and domestic manufacturers have also successively launched new generation after generation. The new refrigerant with DC frequency conversion is multi-connected. [0003...

AI Technical Summary

Problems solved by technology

If the compressor lubricating oil is missing, the compressor motor bearing and compression chamber will not be effectively lubricated, so that the motor will be under overload working conditions, the temperature rise of the motor will exceed the design requirements, the insulation layer of the motor will age rapidly, and the insulation level will drop. Causes damage to the insulation layer and burns the compressor

[0004] Due to the heavy system load of the multi-connected system, one external unit usually uses two or three compressors to work at the same time, and the refrigerant piping between the internal and external units is long. The amount of lubricating oil is unevenly distributed between the compressors, and even some compressors lack oil due to the lubricating oil being taken away by the refrigerant, which eventually leads to adverse consequences of compressor burnout

[0005] At present, there are many kinds of lubricating oil control for multi-line system compressors on the market, but the existing lubricating oil control methods all require regular oil return control, and the oil return cycle is also short, and it is difficult to enter the oil return at the optimal point.

Moreover, the addition of lubricating oil is injected into the low-pressure liquid storage tank before vacuuming. After the compressor is running, the lubricating oil and the refrigerant are mutually dissolved and then returned to the compressor. The minimum miscible ratio of the lubricating oil and the refrigerant cannot be reliably guaranteed.

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