KR20240026394A - air conditioner and controlling method thereof - Google Patents

Abstract

The disclosed air conditioner includes an indoor unit including an expansion valve and an indoor heat exchanger, a compressor that supplies refrigerant to the indoor unit, a compressor inlet pressure sensor that detects a compressor inlet pressure corresponding to the pressure of the refrigerant flowing into the compressor from the accumulator, and a defrost operation. and a control unit that adjusts the opening degree of the expansion valve of the indoor unit based on the compressor inlet pressure.

Description

Air conditioner and controlling method thereof {air conditioner and controlling method thereof}

The disclosed invention relates to an air conditioner capable of improving defrost operation performance and a control method thereof.

An air conditioner is a device that cools or heats air using the movement of heat generated from evaporation and condensation of a refrigerant, and discharges the cooled or heated air to condition the air in an indoor space. During cooling or heating operation, the air conditioner circulates refrigerant through a compressor, an indoor heat exchanger, and an outdoor heat exchanger, and discharges heat-exchanged air from the indoor heat exchanger into the indoor space, thereby cooling or heating the indoor space.

When a heating operation is performed in a low-temperature, high-humidity external environment, frost may be generated in the outdoor heat exchanger included in the outdoor unit. When frost forms on outdoor heat exchangers, heating capacity is reduced and product reliability is reduced. A defrost operation may be performed after pausing the heating operation to remove frost generated in the outdoor heat exchanger. However, there may be cases where ice attached to the outdoor heat exchanger is not completely removed despite the defrost operation.

The disclosed invention provides an air conditioner and a control method for actively controlling an expansion valve to prevent incomplete defrosting during a defrosting operation and to prevent damage to the compressor.

An air conditioner according to an embodiment includes an indoor unit including an expansion valve and an indoor heat exchanger; A compressor that supplies refrigerant to the indoor unit; a compressor inlet pressure sensor that detects compressor inlet pressure corresponding to the pressure of refrigerant flowing into the compressor from the accumulator; and a control unit that adjusts the opening degree of the expansion valve of the indoor unit based on the compressor inlet pressure during a defrost operation.

The controller may adjust the opening degree of the expansion valve to maintain the compressor inlet pressure within a predetermined pressure range.

The controller may increase the opening degree of the expansion valve based on the compressor inlet pressure becoming less than a predetermined lower limit and decrease the opening degree of the expansion valve based on the compressor inlet pressure becoming greater than the predetermined upper limit.

The controller may gradually reduce the opening degree of the expansion valve to a predetermined standard opening degree in response to entering the defrost operation and then adjust the opening degree of the expansion valve based on the compressor inlet pressure.

The air conditioner further includes a compressor outlet temperature sensor that detects the discharge temperature of the refrigerant discharged from the compressor, and the control unit determines that the discharge temperature of the refrigerant becomes higher than a predetermined first critical temperature during the defrost operation. Thus, the frequency of the compressor can be reduced while increasing the opening degree of the expansion valve.

The controller may end the defrost operation based on the discharge temperature of the refrigerant becoming higher than the second critical temperature, which is higher than the first critical temperature.

The air conditioner further includes a compressor outlet pressure sensor that detects a compressor outlet pressure corresponding to the pressure of the refrigerant discharged from the compressor, and the control unit converts the condensation temperature from the discharge temperature of the refrigerant and the compressor outlet pressure. Based on this, the discharge superheat of the compressor may be determined, and the defrost operation may be terminated based on the discharge superheat of the compressor becoming less than a predetermined threshold.

The control unit may control the compressor inlet pressure sensor to detect the compressor inlet pressure at a predetermined detection period.

In a control method of an air conditioner including an indoor unit including an expansion valve and a compressor that supplies refrigerant to the indoor unit, the control method of an air conditioner according to an embodiment includes the method of controlling the air conditioner according to an embodiment, wherein the refrigerant flowing into the compressor from the accumulator during a defrost operation is detecting the compressor inlet pressure corresponding to the pressure of the refrigerant; and adjusting the opening degree of the expansion valve of the indoor unit based on the compressor inlet pressure.

The opening degree of the expansion valve may be adjusted to maintain the compressor inlet pressure within a predetermined pressure range.

Adjusting the opening degree of the expansion valve includes increasing the opening degree of the expansion valve based on the compressor inlet pressure becoming less than a predetermined lower limit value; It may include reducing the opening degree of the expansion valve based on the compressor inlet pressure becoming greater than a predetermined upper limit.

Adjusting the opening degree of the expansion valve may be performed based on the compressor inlet pressure after gradually reducing the opening degree of the expansion valve to a predetermined reference opening degree in response to entering the defrost operation.

The control method of the air conditioner further includes detecting the discharge temperature of the refrigerant discharged from the compressor during the defrost operation, and adjusting the opening degree of the expansion valve may be performed by adjusting the opening degree of the expansion valve to determine the discharge temperature of the refrigerant in advance. It may include reducing the frequency of the compressor while increasing the opening degree of the expansion valve based on the temperature becoming higher than a predetermined first critical temperature.

The defrost operation may be terminated based on the discharge temperature of the refrigerant becoming higher than the second critical temperature that is higher than the first critical temperature.

The control method of the air conditioner includes: detecting a compressor outlet pressure corresponding to the pressure of the refrigerant discharged from the compressor; It further includes determining the discharge superheat of the compressor based on the discharge temperature of the refrigerant and the condensation temperature converted from the compressor outlet pressure, wherein the defrost operation is performed when the discharge superheat of the compressor is greater than a predetermined threshold. It can be terminated based on getting smaller.

The compressor inlet pressure may be detected at predetermined detection intervals.

The disclosed air conditioner and its control method can prevent incomplete defrosting and damage to the compressor by actively controlling the expansion valve during a defrosting operation. The disclosed air conditioner and its control method can quickly determine the circulating amount of refrigerant using the compressor inlet pressure, and can quickly adjust the opening degree of the expansion valve accordingly. By appropriately controlling the circulating amount of refrigerant through active control of the rapid expansion valve during defrost operation, defrost performance can be strengthened and product reliability can be improved.

1 is an external view of an air conditioner according to an embodiment.
Figure 2 shows the flow of refrigerant when an air conditioner performs a heating operation or cooling operation according to an embodiment.
Figure 3 is a block diagram showing the control configuration of an outdoor unit according to an embodiment.
Figure 4 is a block diagram showing a control configuration of an indoor unit according to an embodiment.
Figure 5 is a flowchart explaining a control method of an air conditioner according to an embodiment.
FIG. 6 is a flowchart explaining in more detail the control method of the air conditioner described in FIG. 5.
7 is a flowchart explaining compressor protection control performed during defrost operation.
Figure 8 is a graph showing the change in compressor inlet pressure and the corresponding change in the opening degree of the expansion valve during the defrost operation.
Figure 9 is a graph showing the change in compressor discharge temperature during a defrost operation and the corresponding change in the opening degree of the expansion valve.

The embodiments described in this specification and the configurations shown in the drawings are only preferred examples of the disclosed invention, and at the time of filing this application, there may be various modifications that can replace the embodiments and drawings in this specification.

Throughout this specification, when a part is said to be “connected” to another part, this includes not only direct connection but also indirect connection, and indirect connection refers to connection through a wireless communication network. Includes.

Additionally, the terms used herein are used to describe embodiments and are not intended to limit and/or limit the disclosed invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. The existence or addition of numbers, steps, operations, components, parts, or combinations thereof is not excluded in advance.

In addition, terms including ordinal numbers such as “first”, “second”, etc. used in this specification may be used to describe various components, but the components are not limited by the terms, and the terms It is used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention.

Additionally, terms such as "~unit", "~unit", "~block", "~member", and "~module" may refer to a unit that processes at least one function or operation. For example, the terms may refer to at least one hardware such as a field-programmable gate array (FPGA) / application specific integrated circuit (ASIC), at least one software stored in memory, or at least one process processed by a processor. there is.

The codes attached to each step are used to identify each step, and these codes do not indicate the order of each step. Each step is performed differently from the specified order unless a specific order is clearly stated in the context. It can be.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

1 is an external view of an air conditioner according to an embodiment.

Referring to FIG. 1, the air conditioner 1 includes an outdoor unit 1a provided in an outdoor space to perform heat exchange between outdoor air and a refrigerant, and an indoor unit 1b provided in an indoor space to perform heat exchange between indoor air and a refrigerant. ) includes. The outdoor unit 1a may be located outside the air conditioning space, and the indoor unit 1b may be located within the air conditioning space. The air conditioned space refers to a space that is cooled or heated by the air conditioner (1). For example, the outdoor unit 1a may be placed outside a building, and the indoor unit 1b may be placed in a space separated from the outside by a wall, such as a living room or office. The indoor unit 1b may be installed on the ceiling.

The outdoor unit 1a and the indoor unit 1b are connected through external pipes P1 and P2. The refrigerant can circulate through the outdoor unit (1a), external pipes (P1, P2), and indoor unit (1b). One end of the external pipes P1 and P2 may be connected to a pipe valve provided on one side of the outdoor unit 1a. Additionally, the external pipes P1 and P2 may be connected to refrigerant pipes provided inside the outdoor unit 1a and the indoor unit 1b.

The outdoor unit 1a may include a cabinet 10 forming the exterior, a fan cover 20 covering the top of the cabinet 10, and an outdoor fan 150 disposed within the cabinet 10. The cabinet 10 may form four sides of the outdoor unit 1a. Although the number of outdoor fans 150 is illustrated as two, it is not limited thereto. The outdoor fan 150 may be placed at the top of the cabinet 10. Additionally, an outdoor heat exchanger 130 may be disposed within the cabinet 10.

A fan guard 22 may be provided on the fan cover 20 to discharge air and protect the outdoor fan 150. The fan cover 20 may include an outlet corresponding to the shape of the outdoor fan 150. The fan guard 22 may cover the discharge port of the fan cover 20 and may have a grill or mesh shape. By operating the outdoor fan 150, outdoor air may pass through the inside of the cabinet 10 of the outdoor unit 1a and then be discharged to the outside of the cabinet 10. Air flowing by the operation of the outdoor fan 150 may be discharged to the outside of the outdoor unit 1a through the fan guard 22.

In FIG. 1, the air conditioner 1 is illustrated as including one outdoor unit 1a and one indoor unit 1b, but the air conditioner 1 includes a plurality of outdoor units 1a and a plurality of indoor units 1b. It may also include . For example, a plurality of indoor units 1b may be connected to one outdoor unit 1a. Additionally, the shape of the indoor unit 1b is not limited to that described. As long as the indoor unit 1b is installed in an indoor space and can cool or heat the indoor space, any type of indoor unit 1b can be applied.

Figure 2 shows the flow of refrigerant when an air conditioner performs a heating operation or cooling operation according to an embodiment.

Referring to FIG. 2, the air conditioner 1 includes a refrigerant flow path for circulating refrigerant between the indoor unit 1b and the outdoor unit 1a. The refrigerant circulates between the indoor unit 1b and the outdoor unit 1a along the refrigerant flow path, and can absorb or release heat through a change in state (e.g., a state change from gas to liquid, or a state change from liquid to gas). You can.

The air conditioner (1) may include a liquid pipe (P1) that connects the outdoor unit (1a) and the indoor unit (1b) and serves as a passage through which the liquid refrigerant flows, and a gas pipe (P2) as a passage through which the gaseous refrigerant flows. there is. The liquid pipe (P1) and the gas pipe (P2) may extend inside the outdoor unit (1a) and the indoor unit (1b).

During cooling operation, the refrigerant may emit heat from the outdoor heat exchanger 130 and absorb heat from the indoor heat exchanger 230. During cooling operation, the refrigerant compressed in the compressor 110 may first be supplied to the outdoor heat exchanger 130 through the four-way valve 120 and then to the indoor heat exchanger 230 through the expansion valve 220. During cooling operation, the outdoor heat exchanger 130 operates as a condenser that condenses the refrigerant, and the indoor heat exchanger 230 operates as an evaporator that evaporates the refrigerant.

During cooling operation, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 moves to the outdoor heat exchanger 130. The liquid or near-liquid refrigerant condensed in the outdoor heat exchanger 130 is expanded and depressurized in the expansion valve 220. Two-phase refrigerant that has passed through the expansion valve 220 moves to the indoor heat exchanger 230. The refrigerant flowing into the indoor heat exchanger 230 exchanges heat with the surrounding air and is evaporated. Accordingly, the temperature of the heat-exchanged surrounding air decreases and cold air is discharged to the outside of the indoor unit 1b.

During heating operation, the refrigerant may emit heat from the indoor heat exchanger 230 and absorb heat from the outdoor heat exchanger 130. That is, during the heating operation, the refrigerant compressed in the compressor 110 may be first supplied to the indoor heat exchanger 230 through the four-way valve 120 and then to the outdoor heat exchanger 130. In this case, the indoor heat exchanger 230 operates as a condenser that condenses the refrigerant, and the outdoor heat exchanger 130 operates as an evaporator that evaporates the refrigerant.

During the heating operation, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 moves to the indoor heat exchanger 230. The high-temperature, high-pressure gaseous refrigerant passing through the indoor heat exchanger 230 exchanges heat with low-temperature dry air. The refrigerant condenses into a liquid or near-liquid refrigerant and releases heat, and as the air absorbs the heat, warmth is discharged to the outside of the indoor unit 1b.

The outdoor unit 1a includes a compressor 110 that compresses the refrigerant, an outdoor heat exchanger 130 that performs heat exchange between outdoor air and the refrigerant, and a refrigerant compressed by the compressor 110 based on a cooling operation or a heating operation. Includes a 4-way valve 120 that guides the heat exchanger 130 or the indoor heat exchanger 230, and an accumulator 160 that prevents liquid refrigerant that has not evaporated from flowing into the compressor 110. do.

The compressor 110 may operate by receiving electrical energy from an external power source. The compressor 110 includes a compressor motor (not shown) and compresses low-pressure gaseous refrigerant to high pressure using the rotational force of the compressor motor. The frequency of the compressor 110 may be changed to correspond to the capability required by the indoor unit 1b. The compressor 110 may be an inverter air compressor, a positive displacement compressor, or a dynamic compressor, and various types of compressors that the designer can consider may be used.

The four-way valve 120 can change the flow direction of the high-temperature, high-pressure gas refrigerant discharged from the compressor 110. The four-way valve 120 is controlled to guide the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 during cooling operation, and is controlled to guide the refrigerant compressed by the compressor 110 to the indoor unit 1b during heating operation. do.

The outdoor heat exchanger 130 functions as a condenser to condense the refrigerant compressed in the compressor 110 during cooling operation, and as an evaporator to evaporate the refrigerant decompressed in the indoor unit 1b during heating operation. The outdoor heat exchanger 130 may include an outdoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and outdoor heat exchanger cooling fins (not shown) to increase the surface area in contact with outdoor air. If the surface area in contact between the outdoor heat exchanger refrigerant pipe (not shown) and outdoor air is increased, the heat exchange efficiency between the refrigerant and outdoor air can be improved.

The outdoor fan 150 is provided around the outdoor heat exchanger 130 to flow outdoor air into the outdoor heat exchanger 130. The outdoor fan 150 can blow outdoor air before heat exchange to the outdoor heat exchanger 130 and simultaneously blow the heat-exchanged air outdoors. The outdoor fan 150 can disperse the heat emitted by the liquefaction of the refrigerant in the outdoor heat exchanger 130 by discharging air around the outdoor heat exchanger 130 to the outside.

The accumulator 160 may store liquid refrigerant and vaporize the stored liquid refrigerant. The accumulator 160 can prevent liquid refrigerant from flowing into the compressor 110. However, if the circulating amount of refrigerant is excessive, vaporization of the liquid refrigerant by the accumulator 160 may not be properly performed. In this case, liquid refrigerant may flow into the compressor 110, and damage to the compressor 110 may occur.

The outdoor unit 1a may include an outdoor temperature sensor 171 to detect the outdoor temperature. An outdoor heat exchanger temperature sensor 172 may be provided on at least one side of the outdoor heat exchanger 130 to detect the temperature of the outdoor heat exchanger 130. The outdoor temperature sensor 171 and the outdoor heat exchanger temperature sensor 172 may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer.

Based on a cooling operation in which refrigerant flows from the compressor 110 to the outdoor heat exchanger 130, the outdoor heat exchanger temperature sensor 172 may be placed on the outlet side of the outdoor heat exchanger 130 from which the refrigerant comes out. Therefore, the outdoor heat exchanger temperature sensor 172 may be referred to as an ‘outdoor heat exchanger outlet temperature sensor’. Although not shown, a temperature sensor (not shown) may also be provided on the inlet side of the outdoor heat exchanger 130, and may be referred to as an 'outdoor heat exchanger inlet temperature sensor'. In other words, temperature sensors may be provided at each of the inlet and outlet of the outdoor heat exchanger 130. The outdoor heat exchanger temperature sensor 172 may be installed around the inlet and/or outlet of the outdoor heat exchanger 130, or may be installed in contact with a refrigerant pipe connected to the inlet and/or outlet of the outdoor heat exchanger 130. .

In the heating operation, the circulation direction of the refrigerant is reversed, so the inlet of the outdoor heat exchanger 130, where the refrigerant enters, and the outlet of the outdoor heat exchanger 130, where the refrigerant comes out, may be defined as opposite. However, for convenience of explanation, the inlet and outlet of the outdoor heat exchanger 130 may be described based on the time of cooling operation.

A compressor outlet temperature sensor 173 may be provided at the outlet of the compressor 110. The compressor outlet temperature sensor 173 can detect the discharge temperature of the refrigerant discharged from the compressor 110. The discharge temperature of the refrigerant discharged from the compressor 110 may be referred to as compressor discharge temperature or compressor outlet temperature.

A compressor inlet pressure sensor 174 may be provided at the inlet of the compressor 110. The compressor inlet pressure sensor 174 may detect the pressure of the refrigerant flowing into the compressor 110 from the accumulator 160. The pressure of the refrigerant flowing into the inlet of the compressor 110 may be referred to as compressor inlet pressure.

Additionally, a compressor outlet pressure sensor 175 may be provided at the outlet of the compressor 110. The compressor outlet pressure sensor 175 can detect the pressure of the refrigerant discharged through the outlet of the compressor 110. The pressure of the refrigerant discharged to the outlet of the compressor 110 may be referred to as compressor outlet pressure.

The indoor unit 1b may include an expansion valve 220, an indoor heat exchanger 230, and an indoor fan 250. The indoor heat exchanger 230 performs heat exchange between indoor air and refrigerant. The indoor fan 250 may flow indoor air into the indoor heat exchanger 230. A plurality of indoor fans 250 may be provided.

The expansion valve 220 can expand a high-temperature, high-pressure liquid refrigerant and discharge a low-temperature, low-pressure gas and liquid refrigerant mixture. The expansion valve 220 may control the amount of refrigerant provided to the indoor heat exchanger 230. The expansion valve 220 depressurizes the refrigerant using a throttling action. The throttling action means that when the refrigerant passes through a narrow passage, the pressure decreases without heat exchange with the outside.

The expansion valve 220 may be an electronic expansion valve (EEV) whose opening is adjustable. The expansion valve 220 includes, for example, a thermoelectric electromagnetic expansion valve using deformation of a bimetal, a thermoelectric electromagnetic expansion valve using volume expansion by heating the encapsulating wax, and a pulse width modulation valve that opens and closes a solenoid valve by a pulse signal. It may be an electronic expansion valve or a stem motor-type electronic expansion valve that opens and closes the valve using a motor.

Although the expansion valve 220 is illustrated as being included in the indoor unit 1b, the expansion valve 220 may also be included in the outdoor unit 1a. Additionally, expansion valves 220 may be provided in both the outdoor unit 1a and the indoor unit 1b. That is, the expansion valve 220 may be provided in the liquid pipe P1, which is a pipe that forms a refrigerant flow path between the outdoor heat exchanger 130 and the indoor heat exchanger 230.

The indoor heat exchanger 230 functions as an evaporator to evaporate low-pressure liquid refrigerant during cooling operation, and as a condenser to condense high-pressure gaseous refrigerant during heating operation. The indoor heat exchanger 230, like the outdoor heat exchanger 130 of the outdoor unit 1a, cools the indoor heat exchanger to improve the heat exchange efficiency between the indoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes and the refrigerant and indoor air. Includes pins (not shown).

The indoor fan 250 is provided around the indoor heat exchanger 230 to blow indoor air into the indoor heat exchanger 230. The indoor heat exchanger 230 can perform heat exchange with indoor air. The indoor fan 250 can blow indoor air before heat exchange to the indoor heat exchanger 230 and simultaneously blow the heat-exchanged air into the indoor space.

Indoor heat exchanger temperature sensors 211 and 212 may be provided on both sides (inlet and outlet) of the indoor heat exchanger 230 to detect the temperature of the indoor heat exchanger 230. The indoor heat exchanger temperature sensors 211 and 212 are installed around the inlet and/or outlet of the indoor heat exchanger 230, or are installed to contact the refrigerant pipe connected to the inlet and/or outlet of the indoor heat exchanger 230. You can.

The indoor heat exchanger temperature sensors 211 and 212 may include an indoor heat exchanger inlet temperature sensor 211 and an indoor heat exchanger outlet temperature sensor 212. The indoor heat exchanger inlet temperature sensor 211 can detect the inlet temperature of the indoor heat exchanger 230, and the indoor heat exchanger outlet temperature sensor 212 can detect the outlet temperature of the indoor heat exchanger 230. The inlet of the indoor heat exchanger 230, where the refrigerant enters, and the outlet of the indoor heat exchanger 230, where the refrigerant comes out, may be defined as opposite to each other in cooling and heating operations. However, for convenience of explanation, the inlet and outlet of the indoor heat exchanger 230 may be described based on the time of cooling operation.

Additionally, an indoor temperature sensor 213 may be provided inside the indoor unit 1b to detect the indoor temperature. The indoor heat exchanger temperature sensors 211 and 212 and the indoor temperature sensor 213 may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer.

In addition, the air conditioner 1 may include various temperature sensors.

Figure 3 is a block diagram showing the control configuration of an outdoor unit according to an embodiment.

Referring to FIG. 3, the outdoor unit 1a of the air conditioner 1 includes a compressor 110, a four-way valve 120, an outdoor fan 150, an outdoor temperature sensor 171, and an outdoor heat exchanger temperature sensor 172. , It may include a compressor outlet temperature sensor 173, a compressor inlet pressure sensor 174, a compressor outlet pressure sensor 175, a first communication interface 180, and a first control unit 190. The first control unit 190 may include a first memory 192 and a first processor 191.

The first control unit 190 may be electrically connected to the components of the outdoor unit 1a and control the operation of each component. For example, the first control unit 190 can adjust the frequency of the compressor 110 and control the four-way valve 120 to change the circulation direction of the refrigerant. The first control unit 190 can adjust the rotation speed of the outdoor fan 150. The rotation speed of the outdoor fan 150 may be adjusted according to the outdoor temperature. Additionally, the first control unit 190 may generate a control signal to adjust the opening degree of the expansion valve 220 of the indoor unit 1b.

Under the control of the first control unit 190, the refrigerant flows along the refrigerant circulation circuit including the compressor 110, the four-way valve 120, the outdoor heat exchanger 130, the expansion valve 220, and the indoor heat exchanger 230. It can circulate. The compressor 110 may compress gaseous refrigerant and discharge high-temperature/high-pressure gaseous refrigerant. Additionally, the compressor 110 may not operate in a blowing operation that does not require cooling or heating.

The four-way valve 120 can change the circulation direction of the refrigerant discharged from the compressor 110 under the control of the first control unit 190. The four-way valve 120 guides the refrigerant compressed in the compressor 110 to the outdoor heat exchanger 130 during cooling operation, and guides the refrigerant compressed in the compressor 110 to the indoor heat exchanger 230 during heating operation. Guide.

The outdoor temperature sensor 171 may transmit an electrical signal corresponding to the detected outdoor temperature to the first control unit 190. The outdoor heat exchanger temperature sensor 172 may transmit an electrical signal corresponding to the detected inlet temperature and/or outlet temperature of the outdoor heat exchanger to the first control unit 190.

The compressor outlet temperature sensor 173 may transmit an electrical signal corresponding to the compressor discharge temperature to the first control unit 190. The compressor inlet pressure sensor 174 may transmit an electrical signal corresponding to the compressor inlet pressure to the first control unit 190. The compressor outlet pressure sensor 175 may transmit an electrical signal corresponding to the compressor outlet pressure to the first control unit 190.

The first communication interface 180 may perform communication with the indoor unit 1b. The first communication interface 180 of the outdoor unit 1a transmits the control signal transmitted from the first control unit 190 to the indoor unit 1b, or transmits the control signal transmitted from the indoor unit 1b to the first control unit 190. It can be delivered. In other words, the outdoor unit 1a and the indoor unit 1b can perform two-way communication. The outdoor unit 1a and the indoor unit 1b can transmit and receive various signals during operation.

The first memory 192 can memorize/store various information necessary for the operation of the air conditioner 1. The first memory 192 may store instructions, applications, data, and/or programs necessary for the operation of the air conditioner 1. For example, the first memory 192 may store programs for cooling, heating, and defrosting operations of the air conditioner 1.

The first memory 192 may include volatile memory such as Static Random Access Memory (S-RAM) or Dynamic Random Access Memory (D-RAM) for temporarily storing data. In addition, the first memory 192 is a non-volatile memory such as Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM), or Electrically Erasable Programmable Read Only Memory (EEPROM) for long-term storage of data. May contain memory.

The first processor 191 may generate a control signal for controlling the operation of the air conditioner 1 based on instructions, applications, data, and/or programs stored in the first memory 192. The first processor 191 is hardware and may include a logic circuit and an operation circuit. The first processor 191 may process data according to programs and/or instructions provided from the first memory 192 and generate control signals according to the processing results. The first memory 192 and the first processor 191 may be implemented as one control circuit or as a plurality of circuits.

Some of the components of the illustrated outdoor unit 1a may be omitted, or other components may be added in addition to the illustrated components of the outdoor unit 1a. For example, the outdoor unit 1a may further include a control panel. The control panel may be provided in the cabinet 10 of the outdoor unit 1a. The control panel can obtain user input related to the operation of the air conditioner 1 and output information about the operation of the air conditioner 1. The control panel may transmit an electrical signal (voltage or current) corresponding to the user input to the first control unit 190. The first control unit 190 may control the operation of the air conditioner 1 based on an electrical signal transmitted from the control panel. The control panel may include buttons and displays.

Figure 4 is a block diagram showing a control configuration of an indoor unit according to an embodiment.

Referring to FIG. 4, the indoor unit 1b of the air conditioner 1 includes an expansion valve 220, an indoor fan 250, an indoor heat exchanger inlet temperature sensor 211, an indoor heat exchanger outlet temperature sensor 212, It may include an indoor temperature sensor 213, a second communication interface 260, and a second control unit 270. The second control unit 270 may include a second memory 272 and a second processor 271. The second control unit 270 of the indoor unit 1b may be electrically connected to the components of the indoor unit 1b and may control the operation of each component.

The indoor heat exchanger inlet temperature sensor 211 may transmit an electrical signal corresponding to the detected inlet temperature to the second processor 271. The indoor heat exchanger outlet temperature sensor 212 may transmit an electrical signal corresponding to the detected outlet temperature to the second processor 271. The indoor temperature sensor 213 may transmit an electrical signal corresponding to the detected indoor temperature to the second processor 271.

The expansion valve 220 can depressurize the refrigerant. Additionally, the expansion valve 220 may adjust the amount of refrigerant supplied to ensure sufficient heat exchange in the outdoor heat exchanger 130 or the indoor heat exchanger 230. The expansion valve 220 depressurizes the refrigerant by using the throttling action of the refrigerant, in which the pressure decreases as the refrigerant passes through a narrow passage.

The second communication interface 260 can communicate with the outdoor unit 1a. The second communication interface 260 of the indoor unit 1b transmits the control signal transmitted from the second control unit 270 to the outdoor unit 1a, or transmits the control signal transmitted from the outdoor unit 200 to the second control unit 270. It can be delivered. For example, a control signal for adjusting the opening degree of the expansion valve 220 may be transmitted from the outdoor unit 1a to the indoor unit 1b. The second control unit 270 may adjust the opening degree of the expansion valve 220 based on a signal transmitted from the first control unit 190 of the outdoor unit 1a.

Additionally, the second communication interface 260 can communicate with an access point (AP) (not shown) provided separately in the air conditioning space, and can be connected to a network through the access point. The second communication interface 260 may communicate with a user terminal device (eg, a smartphone) through an access point. The second communication interface 260 can receive information on the user terminal device connected to the access point and transmit the information on the user terminal device to the second control unit 270. Through this, the user can remotely control the air conditioner (1).

The second memory 272 can memorize/store various information necessary for the operation of the air conditioner 1. The second memory 272 may store instructions, applications, data, and/or programs necessary for the operation of the air conditioner 1. For example, the second memory 272 may store programs for cooling, heating, and defrosting operations of the air conditioner 1. Like the first memory 192, the second memory 272 may include volatile memory and/or non-volatile memory.

The second processor 271 may generate a control signal for controlling the operation of the air conditioner 1 based on instructions, applications, data, and/or programs stored in the second memory 272. The second processor 271 is hardware and may include a logic circuit and an operation circuit. The second processor 271 may process data according to programs and/or instructions provided from the second memory 272 and generate a control signal according to the processing results. The second memory 272 and the second processor 271 may be implemented as one control circuit or as a plurality of circuits.

Some of the components of the illustrated indoor unit 1b may be omitted, or other components may be added in addition to the components of the illustrated indoor unit 1b. For example, the indoor unit 1b may further include a control panel. The control panel can obtain user input related to the operation of the air conditioner 1 and output information about the operation of the air conditioner 1.

As described in FIGS. 3 and 4, the air conditioner 1 may include at least one control unit 190 or 270. Although it has been described that each control unit is provided in the outdoor unit 1a and the indoor unit 1b, an integrated control unit capable of controlling both the outdoor unit 1a and the indoor unit 1b may be provided. Hereinafter, it will be explained that control of the air conditioner 1 is performed by the first control unit 190 of the outdoor unit 1a.

The disclosed air conditioner 1 can perform both cooling operation and heating operation. However, during heating operation, the outdoor heat exchanger 130 may freeze, making normal operation impossible. The defrost operation is performed when frost/frost occurs in the outdoor heat exchanger 130 during the heating operation. In other words, when heating performance deteriorates due to frost formation in the outdoor heat exchanger 130, a defrost operation is performed to remove frost/frost.

The control unit 190 of the outdoor unit 1a may perform a defrost operation based on the temperature of the outdoor heat exchanger 130 being lower than a predetermined reference temperature. The controller 190 may temporarily stop the heating operation to perform the defrost operation. To perform a defrost operation, the control unit 190 may temporarily stop driving the compressor 110 and control the four-way valve 120 to change the circulation direction of the refrigerant. When the compressor 110 operates again, the refrigerant flows from the compressor 110 to the outdoor heat exchanger 130. At the start of the defrost operation, the opening state of the expansion valve 220 may be the maximum open state. The high-temperature, high-pressure refrigerant flowing into the outdoor heat exchanger 130 emits heat from the outdoor heat exchanger 130. Frost generated on the surface of the outdoor heat exchanger 130 may be removed by the emitted heat.

However, there may be cases where the defrost operation is not performed normally. That is, a case may occur where the defrost operation is performed incompletely. For example, if the circulating amount of refrigerant is excessive during the defrost operation and liquid refrigerant flows into the compressor 110, the defrost operation may be forcibly stopped to prevent damage to the compressor 110.

Depending on the installation conditions of the air conditioner 1, there may be cases where the defrost operation is not performed normally. For example, when the length of the pipes P1 and P2 connected between the outdoor unit 1a and the indoor unit 1b is very long (for example, when the pipe length is more than 100 meters), the refrigerant can circulate smoothly. There may be situations where this does not happen.

Additionally, even when the vertical distance between the installation location of the outdoor unit 1a and the installation location of the indoor unit 1b is large, the refrigerant may not circulate smoothly. For example, when the outdoor unit (1a) is installed on the ground and the indoor unit (1b) is installed on a high floor of a building, the refrigerant discharged from the outdoor unit (1a) may not reach the indoor unit (1b), resulting in insufficient circulation of the refrigerant. there is. As a result, defrosting may become incomplete.

The disclosed air conditioner 1 appropriately adjusts the circulating amount of refrigerant through active control of the expansion valve 220 during a defrost operation, thereby preventing incomplete defrosting and preventing damage to the compressor.

Figure 5 is a flowchart explaining a control method of an air conditioner according to an embodiment.

Referring to FIG. 5, the first control unit 190 of the outdoor unit 1a may periodically detect the compressor inlet pressure corresponding to the pressure of the refrigerant flowing into the compressor 110 during the defrost operation (501). The first control unit 190 may control the compressor inlet pressure sensor 174 to detect the compressor inlet pressure at predetermined detection periods.

The detection cycle may be determined differently depending on the installation conditions of the air conditioner (1). For example, the longer the pipe length, the shorter the detection period can be set. The longer the vertical distance between the position of the outdoor unit 1a and the position of the indoor unit 1b, the shorter the detection period can be set. By frequently measuring the compressor inlet pressure, the circulating amount of refrigerant can be quickly determined.

The first control unit 190 of the outdoor unit 1a may adjust the opening degree of the expansion valve 220 of the indoor unit 1b based on the compressor inlet pressure during the defrost operation. The first control unit 190 may adjust the opening degree of the expansion valve 220 to maintain the compressor inlet pressure within a predetermined pressure range (502). For example, the first control unit 190 may increase the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming less than a predetermined lower limit. Additionally, the first control unit 190 may reduce the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming greater than a predetermined upper limit.

The control signal of the expansion valve 220 generated by the first control unit 190 of the outdoor unit 1a may be transmitted to the second control unit 270 of the indoor unit 1b, and the second control unit 270 may transmit the control signal The expansion valve 220 can be controlled in response to reception of .

The disclosed air conditioner 1 can quickly and accurately determine the circulating amount of refrigerant by detecting the compressor inlet pressure during a defrost operation, and can quickly adjust the opening degree of the expansion valve 220 accordingly.

The opening degree of the expansion valve 220 may be adjusted based on a decrease in the discharge superheat of the compressor 110. However, a decrease in the discharge superheat of the compressor 110 means that liquid refrigerant has flowed into the compressor 110. Therefore, adjusting the opening degree of the expansion valve 220 according to the discharge superheat of the compressor 110 may not be effective in preventing damage to the compressor 110. The disclosed air conditioner 1 can more effectively prevent damage to the compressor 110 and prevent incomplete defrosting by controlling the expansion valve 220 according to the compressor inlet pressure detected by the compressor inlet pressure sensor 174. It can be prevented effectively.

The first control unit 190 may end the defrost operation based on satisfying the defrost operation end condition (503). The defrost operation termination condition may include a defrost operation completion condition or a compressor protection condition.

For example, the first control unit 190 may determine that the defrost operation is complete when a predetermined reference defrost time has elapsed and end the defrost operation. Additionally, the first control unit 190 may determine that the defrost operation is complete when the temperature of the outdoor heat exchanger 130 reaches a predetermined normal temperature, and may end the defrost operation.

The first control unit 190 may adjust the frequency of the compressor 110 or forcibly terminate the defrost operation according to compressor protection conditions. Compressor protection conditions refer to conditions related to failure or damage of the compressor 110. The compressor protection condition may include the compressor outlet temperature (discharge temperature of the refrigerant discharged from the compressor) exceeding a predetermined threshold temperature.

Additionally, the compressor protection condition may include that the discharge superheat of the compressor 110 is less than a predetermined threshold. The discharge superheat of the compressor 110 may be determined based on the condensation temperature and compressor outlet temperature corresponding to the compressor outlet pressure. The discharge superheat can be calculated as the difference between the compressor outlet temperature and the condensation temperature corresponding to the compressor outlet pressure. Data regarding the condensation temperature corresponding to the compressor outlet pressure may be previously stored in the memory 192.

If the compressor protection condition is met, the control unit 190 may reduce the frequency of the compressor 110 or stop the operation of the compressor 110. The defrost operation can be performed again after compressor protection according to the compressor protection conditions is released.

FIG. 6 is a flowchart explaining in more detail the control method of the air conditioner described in FIG. 5.

Referring to FIG. 6, the first control unit 190 of the air conditioner 1 may enter a defrost operation to remove frost/frost generated in the outdoor heat exchanger 130 during the heating operation (601). At the start of the defrost operation, the opening state of the expansion valve 220 may be the maximum open state. The first control unit 190 may reduce the opening degree of the expansion valve 220 in response to entering the defrost operation (602). The first control unit 190 may gradually reduce the opening degree of the expansion valve 220 to a predetermined reference opening degree in response to entering the defrost operation.

Thereafter, the first control unit 190 may adjust the opening degree of the expansion valve 220 based on the compressor inlet pressure detected by the compressor inlet pressure sensor 174. The first control unit 190 may identify whether the compressor inlet pressure falls within a predetermined pressure range. The first control unit 190 may identify whether the compressor inlet pressure is less than a predetermined lower limit. Additionally, the first control unit 190 may identify whether the compressor inlet pressure is greater than a predetermined upper limit.

The first control unit 190 increases the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming less than a predetermined lower limit (603, 604). Additionally, the first control unit 190 reduces the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming greater than a predetermined upper limit (605, 602). If the compressor inlet pressure falls within a predetermined pressure range, the first control unit 190 may determine to maintain the opening degree of the expansion valve 220 of the indoor unit 1b (606).

In this way, the disclosed air conditioner 1 adjusts the opening degree of the expansion valve 220 so that the compressor inlet pressure is maintained within a predetermined pressure range during the defrost operation, thereby preventing damage to the compressor 110 due to excessive refrigerant circulation. and prevents incomplete defrosting due to insufficient refrigerant circulation.

The first control unit 190 of the air conditioner 1 may end the defrost operation based on the defrost being completed (607, 608). For example, the first control unit 190 may determine that the defrost operation is complete when a predetermined reference defrost time elapses after the start of the defrost operation or when the temperature of the outdoor heat exchanger 130 reaches a predetermined normal temperature. . As the defrost operation is completed, the heating operation can be performed again.

7 is a flowchart explaining compressor protection control performed during defrost operation.

Referring to FIG. 7 , the first control unit 190 of the air conditioner 1 may control the operation of the compressor 110 based on the compressor outlet temperature during the defrost operation. The compressor outlet temperature refers to the discharge temperature of the refrigerant discharged from the compressor 110.

When the opening degree of the expansion valve 220 decreases (602), the circulating amount of refrigerant decreases, the amount of liquid refrigerant flowing into the accumulator 160 decreases, and the compressor outlet temperature increases. If the compressor outlet temperature exceeds a certain temperature, the reliability of the compressor 110 may decrease. The disclosed air conditioner 1 can perform compressor protection control by monitoring the compressor outlet temperature during a defrost operation.

The first control unit 190 of the air conditioner 1 operates the expansion valve based on the discharge temperature (i.e., compressor outlet temperature) of the refrigerant discharged from the compressor 110 during the defrost operation becoming higher than the predetermined first critical temperature. The frequency of the compressor 110 can be reduced while increasing the opening degree (220) (701, 703). When the opening degree of the expansion valve 220 increases and the frequency of the compressor 110 decreases, the compressor outlet temperature may decrease.

The first control unit 190 terminates the defrost operation based on the discharge temperature (i.e., compressor outlet temperature) of the refrigerant discharged from the compressor 110 during the defrost operation becoming higher than the second critical temperature that is higher than the first critical temperature. It can be done (702, 608). That is, when the compressor outlet temperature becomes higher than the second critical temperature, the operation of the compressor 110 may be stopped.

Figure 8 is a graph showing the change in compressor inlet pressure and the corresponding change in the opening degree of the expansion valve during the defrost operation.

Referring to FIG. 8, at time t0, which is the start time of the defrost operation, the opening state of the expansion valve 220 may be the maximum open state (d_max). The first control unit 190 may gradually reduce the opening degree of the expansion valve 220 to a predetermined reference opening degree d1 in response to entering the defrost operation. As the opening degree of the expansion valve 220 decreases, the circulating amount of refrigerant decreases, and the amount of refrigerant flowing into the inlet of the compressor 110 decreases, so the compressor inlet pressure decreases.

The air conditioner 1 increases the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming less than the predetermined lower limit value Ps1. The compressor inlet pressure detected at time t1 may be less than the lower limit value (Ps1). As the opening degree of the expansion valve 220 increases from time t1, the circulating amount of refrigerant increases and the compressor inlet pressure also increases.

Additionally, the air conditioner 1 reduces the opening degree of the expansion valve 220 based on the compressor inlet pressure becoming greater than the predetermined upper limit value Ps2. The compressor inlet pressure detected at time t2 may be greater than the upper limit value (Ps2). From time t2, as the opening degree of the expansion valve 220 decreases, the circulating amount of refrigerant decreases and the compressor inlet pressure decreases again.

Figure 9 is a graph showing the change in compressor discharge temperature during a defrost operation and the corresponding change in the opening degree of the expansion valve.

Referring to FIG. 9, after the start of the defrost operation, the compressor outlet temperature increases as the opening degree of the expansion valve 220 decreases. The air conditioner 1 may increase the opening degree of the expansion valve 220 based on the compressor outlet temperature becoming higher than the predetermined first critical temperature To1. At the same time, the frequency of the compressor 110 can be reduced. The compressor outlet temperature detected at time t3 may be higher than the first critical temperature (To1). From time t3, as the opening degree of the expansion valve 220 increases, the compressor outlet temperature decreases.

When the opening degree of the expansion valve 220 decreases again from time t4, the compressor outlet temperature increases again. The air conditioner 1 may end the defrost operation based on the compressor outlet temperature becoming higher than the second critical temperature To2, which is higher than the first critical temperature. The compressor outlet temperature detected at time t5 may be higher than the second critical temperature (To2). The first control unit 190 may stop driving the compressor 110 at time t5 and end the defrost operation.

The disclosed air conditioner and its control method can prevent incomplete defrosting and damage to the compressor by actively controlling the expansion valve during a defrosting operation. The disclosed air conditioner and its control method can quickly determine the circulating amount of refrigerant using the compressor inlet pressure, and can quickly adjust the opening degree of the expansion valve accordingly. By appropriately controlling the circulating amount of refrigerant through active control of the rapid expansion valve during defrost operation, defrost performance can be strengthened and product reliability can be improved.

Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium that stores instructions executable by a computer. Instructions may be stored in the form of program code, and when executed by a processor, may create program modules to perform operations of the disclosed embodiments.

A storage medium that can be read by a device may be provided in the form of a non-transitory storage medium. Here, 'non-transitory storage medium' simply means that it is a tangible device and does not contain signals (e.g. electromagnetic waves). This term refers to cases where data is semi-permanently stored in a storage medium and temporary storage media. It does not distinguish between cases where it is stored as . For example, a 'non-transitory storage medium' may include a buffer where data is temporarily stored.

Methods according to various embodiments disclosed in this document may be provided and included in a computer program product. Computer program products are commodities and can be traded between sellers and buyers. The computer program product may be distributed in the form of a machine-readable storage medium (e.g. compact disc read only memory (CD-ROM)) or through an application store (e.g. Play StoreTM) or on two user devices (e.g. It can be distributed (e.g. downloaded or uploaded) directly between smartphones) or online. In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) is stored on a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server. It can be temporarily stored or created temporarily.

As described above, the disclosed embodiments have been described with reference to the attached drawings. A person skilled in the art to which the present invention pertains will understand that the present invention can be practiced in forms different from the disclosed embodiments without changing the technical idea or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

1: Air conditioner
1a: Outdoor unit
1b: indoor unit
110: compressor
120: four-way valve
130: Outdoor heat exchanger
220: expansion valve
250: Indoor heat exchanger

Claims (16)

an indoor unit including an expansion valve and an indoor heat exchanger;
A compressor that supplies refrigerant to the indoor unit;
a compressor inlet pressure sensor that detects compressor inlet pressure corresponding to the pressure of refrigerant flowing into the compressor from the accumulator; and
An air conditioner comprising: a control unit that adjusts the opening degree of the expansion valve of the indoor unit based on the compressor inlet pressure during a defrost operation. According to paragraph 1,
The control unit
An air conditioner that adjusts the opening degree of the expansion valve so that the compressor inlet pressure is maintained within a predetermined pressure range. According to paragraph 2,
The control unit
increasing the opening degree of the expansion valve based on the compressor inlet pressure becoming less than a predetermined lower limit,
An air conditioner that reduces the opening degree of the expansion valve based on the compressor inlet pressure becoming greater than a predetermined upper limit. According to paragraph 2,
The control unit
An air conditioner that gradually reduces the opening degree of the expansion valve to a predetermined standard opening degree in response to entering the defrost operation, and then adjusts the opening degree of the expansion valve based on the compressor inlet pressure. According to paragraph 1,
It further includes a compressor outlet temperature sensor that detects the discharge temperature of the refrigerant discharged from the compressor,
The control unit
An air conditioner that reduces the frequency of the compressor while increasing the opening degree of the expansion valve based on the discharge temperature of the refrigerant becoming higher than a predetermined first critical temperature during the defrosting operation. According to clause 5,
The control unit
An air conditioner that terminates the defrost operation based on the discharge temperature of the refrigerant becoming higher than a second critical temperature that is higher than the first critical temperature. According to clause 5,
It further includes a compressor outlet pressure sensor that detects a compressor outlet pressure corresponding to the pressure of the refrigerant discharged from the compressor,
The control unit
Determining the discharge superheat degree of the compressor based on the discharge temperature of the refrigerant and the condensation temperature converted from the compressor outlet pressure,
An air conditioner that terminates the defrost operation based on the discharge superheat of the compressor becoming less than a predetermined threshold. According to paragraph 1,
The control unit
An air conditioner that controls the compressor inlet pressure sensor to detect the compressor inlet pressure at a predetermined detection period. In the control method of an air conditioner including an indoor unit including an expansion valve and a compressor supplying refrigerant to the indoor unit,
Detecting a compressor inlet pressure corresponding to the pressure of refrigerant flowing into the compressor from an accumulator during a defrost operation; and
A control method for an air conditioner comprising: adjusting the opening degree of the expansion valve of the indoor unit based on the compressor inlet pressure. According to clause 9,
The opening degree of the expansion valve is
A control method for an air conditioner wherein the compressor inlet pressure is adjusted to maintain within a predetermined pressure range. According to clause 10,
Adjusting the opening degree of the expansion valve is
increasing the opening degree of the expansion valve based on the compressor inlet pressure becoming less than a predetermined lower limit;
Reducing the opening degree of the expansion valve based on the compressor inlet pressure becoming greater than a predetermined upper limit. According to clause 10,
Adjusting the opening degree of the expansion valve is
A method of controlling an air conditioner, which is performed based on the compressor inlet pressure after gradually reducing the opening degree of the expansion valve to a predetermined standard opening degree in response to entering the defrost operation. According to clause 9,
Detecting the discharge temperature of the refrigerant discharged from the compressor during the defrost operation,
Adjusting the opening degree of the expansion valve is
Based on the discharge temperature of the refrigerant becoming higher than a predetermined first critical temperature, decreasing the frequency of the compressor while increasing the opening degree of the expansion valve. According to clause 13,
The defrost operation is
A control method of an air conditioner that is terminated based on the discharge temperature of the refrigerant becoming higher than a second critical temperature that is higher than the first critical temperature. According to clause 13,
detecting a compressor outlet pressure corresponding to the pressure of the refrigerant discharged from the compressor;
It further includes; determining the discharge superheat degree of the compressor based on the condensation temperature converted from the discharge temperature of the refrigerant and the compressor outlet pressure,
The defrost operation is
A control method for an air conditioner that is terminated based on the discharge superheat of the compressor becoming less than a predetermined threshold. According to clause 9,
The compressor inlet pressure is
A control method for an air conditioner that is detected at a predetermined detection cycle.

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