Oil returning method during heating of multi-split air-conditioning unit

Abstract

The invention discloses an oil returning method during heating of a multi-split air-conditioning unit. The oil returning method comprises the following steps of: a, carrying out normal heating on the multi-split air-conditioning unit; b, adjusting an operation frequency of a compressor (1) to an oil returning frequency, adjusting aperture of an external unit electronic expansion valve (2) to an external unit oil returning aperture, adjusting apertures of internal unit electronic expansion valves (3) of all the indoor units to an internal unit oil returning aperture, and returning oil for 2.5-3.5 minutes by maintaining the oil returning frequency of the compressor (1), the external unit oil returning aperture of the external unit electronic expansion valve (2) and the internal unit oil returning aperture of the internal unit electronic expansion valves (3); c, adjusting the operation frequency of the compressor (1) to a normal frequency, and operating for 15-25 seconds; and d, adjusting the aperture of the external unit electronic expansion valve (2) to the normal aperture, and adjusting the apertures of all the internal unit electronic expansion valves (3) to the normal aperture. The oil returning method disclosed by the invention can guarantee good oil returning effect without liquid impact on the compressor, and indoor heating can be continuously carried out in an oil returning process.

Description

technical field [0001] The invention relates to a multi-connected air-conditioning unit, in particular to an oil return method for the multi-connected air-conditioning unit during heating. Background technique [0002] The multi-connected air conditioner unit in the prior art includes an outdoor unit, a plurality of indoor units connected in parallel, and two refrigerant circulation main pipes connecting each indoor unit and the outdoor unit. [0003] Each outdoor unit includes a compressor, an oil separator, a four-way reversing valve, an outdoor heat exchanger (evaporator in heating mode), an electronic expansion valve for the outdoor unit, a liquid receiver, and a gas-liquid separator. The outlet of the compressor is connected with one end of the oil separator, the other end of the oil separator is connected with the first valve port of the four-way reversing valve, and the third valve port of the four-way reversing valve is connected with one of the two refrigerant circu...

AI Technical Summary

Problems solved by technology

There is an insurmountable disadvantage in the traditional oil return method, which is the opening of the indoor electronic expansion valve: if the opening is too small, the refrigerant will be throttled and reduced, causing the lubricating oil to separate from the refrigerant, which is not conducive to return. Oil; if the opening is too large, since the indoor heat exchanger hardly exchanges heat, a large amount of liquid refrigerant will liquid hit the compressor

Moreover, during the oil return process, due to the cooling mode, the indoor heating cannot be continued, and the user cannot use the air conditioner for heating.

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