Three-tube multi-split air-conditioning system oil return or defrosting control method and system thereof

Abstract

The invention relates to a three-tube multi-split air-conditioning system oil return or defrosting control method and a system thereof. The method includes the following steps that step1, a port of refrigerating / heating switching device and an output pipe of an air-conditioning external unit system through a bypass pipe, the bypass pipe is provided with a bypass electromagnetic valve, and whether an air-conditioning system enters the oil return or defrosting state or not is detected in real time; step 2, when the air-conditioning system enters the oil return or defrosting state, an air-conditioning heat recycling device is switched into the refrigerating mode; step 3, an electromagnetic expansion valve of a throttling part of the air-conditioning heat recycling device is turned off, and the bypass electromagnetic valve is turned on; step 4, after the air-conditioning system receives the ending signal of oil return or defrosting, the bypass electromagnetic valve is turned off, and the electromagnetic expansion valve of the throttling part of the air-conditioning recycling device is turned on. According to the three-tube multi-split air-conditioning system oil return or defrosting control method and the system thereof, coolants do not pass through a hydraulic module system, and the situations that the hydraulic module system is frozen due to the coolants, and thus pipes are blocked are avoided on the premise of meeting the oil return and defrosting requirements.

Description

technical field [0001] The invention relates to the technical field of air-conditioning equipment, in particular to a method and system for controlling oil return or defrosting of a three-pipe multi-connected air-conditioning system. Background technique [0002] At present, in order to improve the comfort of air conditioners, there may be different demands for cooling and heating in transitional seasons. For a single set of multi-connected air conditioning system, it must be able to meet the cooling and heating demands at the same time. In the prior art, three The controlled multi-connected air-conditioning system can meet this demand, and multiple indoor units can simultaneously turn on two different modes of cooling or heating. [0003] In the heating mode of the air conditioner, frosting is inevitable. The current practice of most manufacturers is to switch the internal unit to cooling mode once it enters the defrosting mode. In order to reduce the defrosting time, the e...

AI Technical Summary

Problems solved by technology

In this way, the refrigerant will flow through the internal unit, making the coil temperature of the internal unit very low. For the multi-connected system with heat recovery, if a water circulation system is used, when returning oil or defrosting, the refrigerant will pass through the heat recovery device and will be absorbed from the water Heat, resulting in a decrease in the temperature of the outlet water, in the case of low temperatures, may even cause the water in the heat recovery device to freeze, affecting user comfort and system reliability

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