Circuit and method for controlling closing of electronic expansion valve of indoor unit in power failure of multi-split air conditioner

Abstract

The invention discloses a circuit and method for controlling closing of electronic expansion valves of indoor units in power failure of a multi-split air conditioner. When part of indoor units are powered off, an outdoor unit locks the addresses of the indoor units which cannot communicate through inspection, the outdoor unit stops running, and first direct-current voltage is output to the powered-off indoor units through a weak wire; the indoor unit which interrupts communication receives a first direct-current voltage, the first direct-current voltage can be used for an indoor unit switching power supply transformer of the indoor unit to work, a second direct-current voltage is output and supplied to an expansion valve control chip, a third direct-current voltage is output and supplied to an indoor unit CPU, and at the moment, the indoor unit which is powered off and the outdoor unit can also establish communication again; the outdoor unit can sequentially send an expansion valve closing instruction to the indoor unit according to the locked outage indoor unit address bit, after the indoor unit receives the expansion valve closing instruction, the expansion valve control chip controls the expansion valve to be closed, and after the indoor unit is closed, a completion signal is transmitted back to the outdoor unit. And the outdoor unit sends an expansion valve closing instruction to the indoor unit of the next address, and actions are executed in sequence.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and in particular to a circuit and method for controlling the closing of an electronic expansion valve of an indoor unit of a multi-split unit when power is lost. Background Art

[0002] For multi-split air conditioners, one outdoor unit tows multiple indoor units. In actual user use, there may be situations where the indoor units are controlled by multiple power supplies. During the cooling operation of all indoor air conditioners, there may be situations where the user does not shut down the indoor air conditioner and directly cuts off the power supply of the indoor air conditioner. If the expansion valve that controls the refrigerant flow of the indoor unit that has been powered off is still in the open state, the refrigerant flowing through the indoor unit that has been powered off cannot effectively evaporate into a gas state, and will enter the refrigerant main line in the form of a gas-liquid mixture, and eventually flow into the compressor, causing damage to the compressor. In view of the above situation, how to make the indoor unit that has been powered off close the expansion valve to protect the compressor has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to provide a circuit and method for controlling the closing of the electronic expansion valve of the indoor unit of a multi-split air conditioner when the power is off, so as to solve the problem that when the power is off in the existing multi-split air conditioner, the indoor unit fails to close the electronic expansion valve, causing the refrigerant to flow back into the compressor in a gas-liquid mixed state, which easily causes damage to the compressor.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a circuit for controlling the closing of the electronic expansion valve of the indoor unit of a multi-split unit when power is off, comprising an outdoor unit control board and a plurality of indoor unit control boards, characterized in that: the outdoor unit control board is provided with an outdoor unit CPU, an outdoor unit switch power transformer, a normally open relay, a power output port, and an indoor and outdoor unit communication port; the indoor unit control board is provided with an indoor unit CPU, a power access port, an indoor unit switch power transformer, a normally closed relay, an expansion valve control chip, an expansion valve interface, and an indoor and outdoor unit communication port; the outdoor unit CPU is connected to the normally open relay and the indoor and outdoor unit communication port; the outdoor unit switch power transformer is connected to the power output port through the normally open relay; the indoor unit CPU is connected to the normally closed relay, the indoor unit switch power transformer, the expansion valve control chip, and the indoor and outdoor unit communication port; the indoor unit switch power transformer is connected to the normally closed relay; the expansion valve control chip is connected to the indoor unit switch power transformer and the expansion valve interface; the power output port of the outdoor unit is connected to the power access ports of all indoor units through a weak wire; the indoor and outdoor unit communication ports of the outdoor unit are connected to the indoor and outdoor unit communication ports of all indoor units through a communication line.

[0005] A method for controlling the closing of the electronic expansion valve of the indoor unit of a multi-split unit when the power is off by using the circuit, characterized in that the method is that the outdoor unit inspects the indoor unit in real time, when part of the indoor units are powered off, the outdoor unit locks the address of the indoor unit that cannot communicate through inspection, and the outdoor unit stops running, outputs a first DC voltage to the powered-off indoor unit through a weak wire, the indoor unit whose communication is not interrupted does not process the first DC voltage output by the outdoor unit, and the indoor unit whose communication is interrupted receives the first DC voltage, the first DC voltage can be used for the indoor unit switch power supply transformer of the indoor unit to work, and outputs a second DC voltage to supply the expansion valve control chip, and a third DC voltage is supplied to the indoor unit CPU, at this time the powered-off indoor unit and the outdoor unit will also re-establish communication, the outdoor unit will send a closing expansion valve instruction to the indoor unit according to the locked address of the powered-off indoor unit, after the indoor unit receives the closing expansion valve instruction, the expansion valve control chip controls the closing of the expansion valve, after the indoor unit is closed, a completion signal is sent back to the outdoor unit, the outdoor unit sends a closing expansion valve instruction to the indoor unit of the next address, and the actions are executed in sequence, when all the powered-off indoor units have closed the expansion valves in sequence, the outdoor unit CPU will stop outputting the first DC voltage.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] The present invention can effectively prevent the user from stopping the indoor unit by directly turning off the power switch, thereby causing the indoor unit that has been powered off to be unable to close the expansion valve that controls the refrigerant flow rate, and the indoor unit fan also being unable to operate due to the power outage. The refrigerant flows into the running compressor in the form of a gas-liquid mixture, causing damage to the internal components of the compressor, thereby extending the life of the compressor and effectively ensuring the service life of the air conditioner. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The schematic diagram of the circuit for controlling the closing of the electronic expansion valve in the multi-split unit of the present invention is shown. DETAILED DESCRIPTION

[0009] Example

[0010] See also Figure 1A circuit for controlling the closing of the electronic expansion valve of the indoor unit of a multi-split unit includes an outdoor unit control board and a plurality of indoor unit control boards. The outdoor unit control board is installed on the outdoor unit, and each indoor unit connected to the outdoor unit is installed with an indoor unit control board. The indoor unit and the outdoor unit have separate power supplies. The outdoor unit control board is provided with an outdoor unit CPU, an outdoor unit switching power transformer, a normally open relay, a 15V power output port, and an indoor and outdoor unit communication port. The indoor unit control board is provided with an indoor unit CPU, a 15V power access port, an indoor unit switching power transformer, a normally closed relay, an expansion valve control chip, an expansion valve interface, and an indoor and outdoor unit communication port. , the outdoor unit CPU is connected to the normally open relay and the indoor and outdoor unit communication port, the outdoor unit switching power supply transformer is connected to the 15V power output port through the normally open relay, the indoor unit CPU is connected to the normally closed relay, the indoor unit switching power supply transformer, the expansion valve control chip, and the indoor and outdoor unit communication port, the indoor unit switching power supply transformer is connected to the normally closed relay and the 15V power access port, the expansion valve control chip is connected to the indoor unit switching power supply transformer and the expansion valve interface, the outdoor unit's 15V power output port is connected to the 15V power access ports of all indoor units through a weak wire, and the outdoor unit's indoor and outdoor unit communication ports are connected to the indoor and outdoor unit communication ports of all indoor units through a communication line.

[0011] During the installation and commissioning phase of the air conditioner, the number of indoor units needs to be locked manually. After the indoor and outdoor units are powered on, the outdoor unit will automatically inspect the number of indoor units connected for communication. At this time, each connected indoor unit will also be assigned its own address. When the number of indoor units inspected is correct, you need to manually turn the confirmation dial on the outdoor unit control panel from OFF to ON to lock the number of indoor units connected for communication and the address bits of each indoor unit.

[0012] The indoor unit and the outdoor unit communicate in real time. Under normal circumstances, when some indoor units need to stop running, the remote controller or wire controller is used to control the shutdown of some indoor units. Under normal circumstances, the electronic expansion valve that regulates the flow of refrigerant will also be closed when the indoor unit is shut down. When multiple indoor units are powered by multiple power supplies, and some indoor units are shut down by directly disconnecting the power supply, the electronic expansion valve that controls the refrigerant cannot be closed normally due to the power failure, which will cause liquid refrigerant to enter the compressor. To avoid this situation, this embodiment also provides a method for controlling the electronic expansion valve of the indoor unit of a multi-split unit to be closed when the power is off by using the above-mentioned circuit, and the method is:

[0013] The outdoor unit inspects the indoor unit in real time. When some indoor units are powered off, the outdoor unit locks the addresses of the indoor units that cannot communicate through inspection, and the outdoor unit stops running. It outputs DC15V voltage to the powered-off indoor unit through the weak wire. The indoor unit that has not interrupted communication does not process the DC15V voltage output by the outdoor unit, while the indoor unit that has interrupted communication receives the DC15V voltage, which can be used for the indoor unit switch power supply transformer of the indoor unit, and outputs DC12V working voltage to supply the expansion valve control chip, and outputs DC5V working voltage to supply the indoor unit CPU. At this time, the powered-off indoor unit and the outdoor unit will also re-establish communication. The outdoor unit will send a command to close the expansion valve to the indoor unit according to the locked address of the powered-off indoor unit. After the indoor unit receives the command to close the expansion valve, the expansion valve control chip controls the expansion valve to close. After the indoor unit is closed, it sends a completion signal to the outdoor unit. The outdoor unit then sends a command to close the expansion valve to the indoor unit at the next address, and the actions are executed in sequence. When all the powered-off indoor units have closed the expansion valves in sequence, the outdoor unit CPU will stop outputting DC15V voltage.

[0014] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circuit for controlling the closing of the electronic expansion valve of the indoor unit of a multi-split system when power is off, comprising an outdoor unit control board and a plurality of indoor unit control boards, characterized in that: The outdoor unit control board is provided with an outdoor unit CPU, an outdoor unit switching power transformer, a normally open relay, a power output port, and an indoor and outdoor unit communication port; the indoor unit control board is provided with an indoor unit CPU, a power access port, an indoor unit switching power transformer, a normally closed relay, an expansion valve control chip, an expansion valve interface, and an indoor and outdoor unit communication port; the outdoor unit CPU is connected to the normally open relay and the indoor and outdoor unit communication port; the outdoor unit switching power transformer is connected to the power output port through the normally open relay; the indoor unit CPU is connected to the normally closed relay, the indoor unit switching power transformer, the expansion valve control chip, and the indoor and outdoor unit communication port; the indoor unit switching power transformer is connected to the normally closed relay; the expansion valve control chip is connected to the indoor unit switching power transformer and the expansion valve interface; the power output port of the outdoor unit is connected to the power access ports of all indoor units through a weak wire; the indoor and outdoor unit communication ports of the outdoor unit are connected to the indoor and outdoor unit communication ports of all indoor units through a communication line.

2. A method for controlling the closing of the electronic expansion valve of the internal unit of a multi-split system when power is off by using the circuit described in claim 1, characterized in that: The method is that the outdoor unit inspects the indoor unit in real time. When some indoor units are powered off, the outdoor unit locks the addresses of the indoor units that cannot communicate through inspection, and the outdoor unit stops running. The first DC voltage is output to the powered-off indoor unit through the weak wire. The indoor unit whose communication is not interrupted does not process the first DC voltage output by the outdoor unit, while the indoor unit whose communication is interrupted receives the first DC voltage, which can be used for the indoor unit switch power supply transformer of the indoor unit to work, and outputs the second DC voltage to supply the expansion valve control chip, and the third DC voltage is supplied to the indoor unit CPU. At this time, the powered-off indoor unit and the outdoor unit will also re-establish communication. The outdoor unit will send a closing expansion valve instruction to the indoor unit according to the locked address of the powered-off indoor unit. After the indoor unit receives the closing expansion valve instruction, the expansion valve control chip controls the closing of the expansion valve. After the indoor unit is closed, it sends a completion signal to the outdoor unit. The outdoor unit then sends a closing expansion valve instruction to the indoor unit with the next address, and the actions are executed in sequence. When all the powered-off indoor units have closed the expansion valves in sequence, the outdoor unit CPU will stop outputting the first DC voltage.

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