Oil returning control method for direct current frequency conversion variable refrigerant flow air conditioner

Abstract

The invention relates to an oil returning control method for a direct current frequency conversion variable refrigerant flow air conditioner. The method comprises the following steps: (1) arranging anoil returning temperature sensor on an oil returning pipeline of a compressor; (2) setting system parameters; and (3) judging whether a system needs the oil returning, wherein the system enters an oil returning mode for operation if the system needs oil returning, and the oil returning is finished after the system enters the oil returning and operates for a period of time if the halt protection or frequency reduction protection of the system is not triggered in the oil returning process. The oil returning control method has the advantages that the oil returning of the system can be effectively ensured when the direct current frequency conversion variable refrigerant flow air conditioner continues to stably operate at high frequency under the mode of high temperature refrigeration, such that the condition that the compressor is burnt out due to oil lack can be effectively avoided, and the damage to the system can be effectively avoided.

Description

technical field [0001] The invention relates to an air conditioner, in particular to an oil return control method for a DC frequency conversion multi-connected air conditioner. Background technique [0002] As we all know, the oil discharge rate of the compressor of the DC inverter multi-connected air conditioning system is different when it operates in different frequency bands. At present, many manufacturers in the industry focus on high-temperature refrigeration (generally refers to the ambient temperature above 40 ° C, such as Africa) mode Under the low-frequency operation of the compressor or the difficulty of oil return during the start-up stage of the compressor, there is little attention to the oil return state under the high-frequency stable operation of the compressor. In fact, when the compressor of the DC inverter multi-split air-conditioning system is running stably at high frequency continuously, the exhaust pressure and temperature of the compressor are both h...

AI Technical Summary

Problems solved by technology

[0002] As we all know, the oil discharge rate of the compressor of the DC inverter multi-connected air conditioning system is different when it operates in different frequency bands. At present, many manufacturers in the industry focus on high-temperature refrigeration (generally refers to the ambient temperature above 40 ° C, such as Africa) mode Under low-frequency operation of the compressor or the difficulty of oil return during the start-up stage of the compressor, there is little attention to the oil return state of the compressor under high-frequency stable operation

In fact, when the compressor of the DC inverter multi-split air-conditioning system is running stably at high frequency continuously, the exhaust pressure and temperature of the compressor are both high (but the condition for triggering the frequency reduction protection for excessive exhaust temperature is not reached) , so the flow rate of refrigerant in the entire DC inverter multi-split air conditioning system is very fast, which makes the compressor always in a state of high-speed oil injection, which will cause the oil discharged from the compressor into the internal unit pipeline to be unable to be brought back to the compressor in time At this time, if the DC inverter multi-split air conditioner system shields the oil return control protection, it may cause the compressor to burn out due to lack of oil, and may even cause damage to the entire DC inverter multi-split air conditioner system