Abstract: Provided are a multi-split air conditioning system and a method and device for controlling oil return of the multi-split air conditioning system. The method includes: acquiring a minimum refrigerant flux required for carrying a lubricating oil in the system back to an outdoor unit and a current refrigerant flux of the system every a first preset time during operation of the system; detecting and determining that the current refrigerant flux is less than or equal to the minimum refrigerant flux; acquiring a total oil discharge amount of a compressor since last time oil return; detecting and determining that the total oil discharge amount is greater than a maximum safe oil discharge amount; and controlling the system to return oil.

Abstract: The present disclosure provides a method for unlocking an air conditioning unit, including: when a server receives first identity information and unit information from a mobile terminal, performing a verification of the first identity information based on the unit information; and sending an unlocking instruction to the air conditioning unit corresponding to the unit information when the first identity information is verified, such that the air conditioning unit performs an unlocking operation based on the unlocking instruction. The present disclosure also provides a device for unlocking an air conditioning unit and a server. The present disclosure realizes unlocking the air conditioning unit when the first identity information is verified, thus ensuring that the current operator (user) is an authorized operator, and thus further avoiding problems that the air conditioning unit still have malfunctions and that irreversible damages are caused to the air conditioning unit.

Abstract: The present disclosure provides a method for unlocking an air conditioning unit, including: when a server receives first identity information and unit information from a mobile terminal, performing a verification of the first identity information based on the unit information; and sending an unlocking instruction to the air conditioning unit corresponding to the unit information when the first identity information is verified, such that the air conditioning unit performs an unlocking operation based on the unlocking instruction. The present disclosure also provides a device for unlocking an air conditioning unit and a server. The present disclosure realizes unlocking the air conditioning unit when the first identity information is verified, thus ensuring that the current operator (user) is an authorized operator, and thus further avoiding problems that the air conditioning unit still have malfunctions and that irreversible damages are caused to the air conditioning unit.

Abstract: An enhanced vapor injection air conditioning system is provided and includes: a vapor injection compressor, a direction switching assembly, a first outdoor heat exchanger, a second outdoor heat exchanger including first and second heat-exchange flow passages, and an auxiliary electronic expansion valve assembly. A main electronic expansion valve assembly is connected between a first end of the first heat-exchange flow passage and a second end of the first outdoor heat exchanger. The auxiliary electronic expansion valve assembly has a first end connected with an inlet of the second heat-exchange flow passage, and a second end connected to a second end of the first heat-exchange flow passage or between the main electronic expansion valve assembly and the first heat-exchange flow passage. A ratio DB of a sum of a caliber of the main electronic expansion valve assembly to that of the auxiliary electronic expansion valve assembly has a range of 1?DB?7.

Abstract: A multi-split air conditioning system having an outdoor unit and multiple indoor units and control method therefor. The control method comprises the following steps: obtaining an outdoor ambient temperature when an indoor unit sends a start instruction received from a user; determining whether the outdoor ambient temperature falls within a preset temperature range; and determining an operation mode of the multi-split system according to operations status of other existing started indoor units when the outdoor ambient temperature falls within the preset temperature range.

Abstract: An enhanced vapor injection air conditioning system (100) is provided and includes: a vapor injection compressor (1), a direction switching assembly (2), a first outdoor heat exchanger (3), a second outdoor heat exchanger (4) including first and second heat-exchange flow passages (41, 42), and an auxiliary electronic expansion valve assembly. A main electronic expansion valve assembly is connected between a first end (411) of the first heat-exchange flow passage and a second end (32) of the first outdoor heat exchanger. The auxiliary electronic expansion valve assembly has a first end connected with an inlet of the second heat-exchange flow passage (42), and a second end connected to a second end (412) of the first heat-exchange flow passage or between the main electronic expansion valve assembly and the first heat-exchange flow passage (41).