Oil return control method and system of variable refrigerant volume air conditioning system

Abstract

The invention discloses an oil return control method and system of a variable refrigerant volume air conditioning system. Whether the average exhaust pressure is larger than or equal to the set threshold value or not is judged by calculating the average exhaust pressure within an oil return cycle; if yes, the heating mode is kept, the good oil return effect is achieved while heating is conducted,the oil return requirement is met, and moreover, the heat effect of an indoor unit is not influenced; if no, the heating mode is switched into the refrigerating mode, a fan of the started indoor unitis controlled to stop, and refrigerating oil return operation is started; and after refrigerating oil return operation is completed, the refrigerating mode is switched into the heating mode. Thus, when the average exhaust pressure is smaller than the set threshold value, the heating mode is switched into the refrigerating mode, the fan of the started indoor unit stops operating, and the influenceon the temperature of a room where the started indoor unit is located is reduced; when the average exhaust pressure is larger than or equal to the set threshold value, the heating mode is kept, oil return is achieved while heating is conducted, accordingly, the variable refrigerant volume air conditioning system has the good oil return effect and the good heating effect, and the situation that theheating effect of the indoor unit is influenced is avoided; and the influence of oil return on the heating effect is reduced.

Description

technical field [0001] The invention belongs to the technical field of air conditioning, and in particular relates to a multi-line oil return control method and system. Background technique [0002] In a multi-split system, the outdoor unit is usually connected to multiple indoor units. The compressor oil in the outdoor unit compressor will flow to each indoor unit in the system along with the refrigerant. When the system is heating, in order to ensure the heating effect of the indoor mechanism when it is turned on, the expansion valve opening of the turned off indoor unit is relatively small, which can only ensure the return of the refrigerant, but it is difficult for the compressor oil in the pipeline to return. Over time, a large amount of pressurized oil will accumulate in the pipeline of the shutdown indoor unit. If the press oil cannot be returned to the press in time, it will cause the press to lack oil, and the press will be easily damaged. [0003] In order to en...

AI Technical Summary

Problems solved by technology

However, when the indoor unit is switched to the cooling state, the original heating indoor unit will absorb heat from the room, causing the room temperature to drop sharply, which will obviously affect the heating effect

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