Air conditioner

Abstract

The application provides an air conditioner. The air conditioner comprises an air conditioner indoor unit, which comprises an indoor heat exchanger; an air conditioner outdoor unit, which comprises an outdoor heat exchanger and a compressor; an electronic expansion valve; a first temperature sensor, which is used for detecting the exhaust temperature of the compressor; a second temperature sensor, which is used for detecting the coil temperature of the outdoor heat exchanger; a third temperature sensor, which is used for detecting the outdoor environment temperature; the defrosting superheat degree is defined as the difference between the exhaust temperature and the coil temperature of the outdoor heat exchanger; and a controller is configured to: determine the defrosting frequency in the defrosting mode according to the detected outdoor environment temperature; obtain a target defrosting superheat degree DSH through a first logical operation according to the outdoor environment temperature, the defrosting frequency and the defrosting operation time def ; and change the opening degree of the electronic expansion valve to make the actual defrosting superheat degree reach the target defrosting superheat degree. With the increase of the defrosting time, the opening degree of the electronic expansion valve is increased, and the target defrosting superheat degree is reduced, which is beneficial to reducing the defrosting heat loss and improving the defrosting speed.

Description

Technical Field

[0001] This invention relates to the field of household appliance technology, and more particularly to an air conditioner. Background Technology

[0002] During the defrosting process of an air conditioner outdoor unit, the heat source is mainly the work done by the compressor. The heat during defrosting is divided into two parts: one part is defrosting heat, which is used to exchange heat with the frost layer and melt the frost into water; the other part is heat loss, which is dissipated into the air after the frost layer has been melted in the heat exchanger section.

[0003] In existing defrosting processes, the electronic expansion valve typically maintains a fixed opening or adjusts its opening to decrease. In this scenario, the exhaust temperature is normal after the defrosting process begins, with most of the heat used for defrosting the initial portion of the heat exchanger flow path. As defrosting progresses, when the electronic expansion valve opening remains constant or decreases, the frost on the outer wall of the initial portion of the refrigerant pipes in the outdoor heat exchanger's refrigerant flow path has melted, causing a rapid increase in condensing pressure and exhaust temperature. At this point, the temperature difference between the exhaust and the outdoor ambient temperature gradually increases, leading to greater defrosting heat loss. This results in less heat being used for defrosting the latter half of the refrigerant pipes in the outdoor heat exchanger's refrigerant flow path, resulting in lower defrosting efficiency. Summary of the Invention

[0004] This invention at least partially solves one of the technical problems in the related art.

[0005] Therefore, this application provides an air conditioner, including: an indoor unit of the air conditioner, which includes an indoor heat exchanger;

[0006] An outdoor unit for an air conditioner includes an outdoor heat exchanger and a compressor. The compressor includes an air intake, an air exhaust, and a compression chamber communicating with the air intake and the air exhaust, so that refrigerant entering the compression chamber from the air intake is compressed by the compressor and discharged from the air exhaust.

[0007] An electronic expansion valve is connected between the indoor heat exchanger and the outdoor heat exchanger to throttle the high-temperature, high-pressure refrigerant liquid after passing through the outdoor heat exchanger into a low-pressure refrigerant liquid.

[0008] A first temperature sensor is installed on a pipe connected to the exhaust port to detect the exhaust temperature of the compressor.

[0009] The second temperature sensor is installed on the refrigerant coil of the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger.

[0010] The third temperature sensor is installed on the outdoor unit of the air conditioner and is used to detect the outdoor ambient temperature;

[0011] The defrost superheat is defined as the difference between the exhaust temperature and the coil temperature of the outdoor heat exchanger.

[0012] The controller is configured as follows:

[0013] The defrosting frequency of the compressor in defrosting mode is determined based on the detected outdoor ambient temperature.

[0014] When the defrost mode is running, the compressor operates at the defrost frequency;

[0015] The target defrost superheat (DSH) is calculated through a first logical operation based on the outdoor ambient temperature, defrost frequency, and defrost operation time in the defrost mode. def ;

[0016] By controlling the opening of the electronic expansion valve to increase, the actual defrost superheat is made to reach the target defrost superheat.

[0017] During the defrosting process of this invention, the controller determines the defrosting frequency of the compressor in defrosting mode based on the outdoor ambient temperature, and sets the target defrosting superheat (DSH) based on the outdoor ambient temperature, defrosting frequency, and defrosting time. def Corrections were made. By adjusting and increasing the opening of the electronic expansion valve in defrost mode, the actual defrost superheat reached the target defrost superheat. This caused the refrigerant two-phase zone of the refrigerant coil in the outdoor heat exchanger to gradually move from the front to the rear of the refrigerant flow path. As a result, most of the heat during defrosting was used for defrosting, reducing heat loss in the refrigerant flow path and improving defrost efficiency.

[0018] In some embodiments of this application, the first logic is configured as follows:

[0019] The superheat factor is obtained by calculating the defrosting frequency with constants A and B.

[0020] The outdoor ambient temperature factor is obtained by calculating the outdoor ambient temperature with constants C and D.

[0021] The defrosting factor is obtained by calculating the defrosting time and the constant E.

[0022] The target defrost superheat is calculated by subtracting the defrost factor from the product of the superheat factor and the room temperature / ambient temperature factor.

[0023] In some embodiments of this application, the first logic is configured as follows:

[0024] Where A, B, C, D, and E are constants, and Fre aimIt is the defrosting frequency in the defrosting mode; Toutdoor is the outdoor ambient temperature in the defrosting mode; t def This refers to the defrosting operation time.

[0025] In some embodiments of this application, when the defrosting mode is run and the opening of the electronic expansion valve is increased, the opening of the electronic expansion valve increases in segments within a preset time period.

[0026] In some embodiments of this application, after the electronic expansion valve increases the preset opening degree in each segment, it detects whether the real-time defrost overheat degree has reached the target defrost overheat degree;

[0027] When the real-time defrosting overheat does not reach the target defrosting overheat, the electronic expansion valve increases the preset opening degree in the next segment of the preset time period;

[0028] When the real-time defrost overheat reaches the target defrost overheat, the electronic expansion valve maintains its current opening degree for the preset time period.

[0029] In some embodiments of this application, the controller has a preset database, and different outdoor ambient temperatures in the database are mapped to corresponding defrosting frequencies; the lower the outdoor ambient temperature in the database, the higher the defrosting frequency.

[0030] In some embodiments of this application, an outdoor fan is provided inside the outdoor unit of the air conditioner, and the outdoor fan stops operating during the defrost mode.

[0031] In some embodiments of this application, the defrosting frequency is positively correlated with the overheating factor, and the defrosting frequency is positively correlated with the target defrosting overheating.

[0032] In some embodiments of this application, the outdoor ambient temperature is negatively correlated with the outdoor ambient temperature factor, and the outdoor ambient temperature is negatively correlated with the target defrost superheat.

[0033] In some embodiments of this application, the defrosting time is positively correlated with the defrosting factor, and the defrosting time is negatively correlated with the target defrosting overheat. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a system schematic diagram of an air conditioner according to an embodiment of this application, in which the indoor heat exchanger acts as the evaporator and the outdoor heat exchanger acts as the condenser.

[0036] Figure 2 This is a system schematic diagram of an air conditioner according to an embodiment of this application, in which the indoor heat exchanger acts as a condenser and the outdoor heat exchanger acts as an evaporator.

[0037] Figure 3 This is a flowchart illustrating the process of determining whether an air conditioner enters defrost mode according to an embodiment of this application.

[0038] Figure 4 This is a control flowchart of an air conditioner in defrost mode according to an embodiment of this application;

[0039] Figure 5 This is a control flowchart of the electronic expansion valve at the start of the defrost mode of an air conditioner according to an embodiment of this application;

[0040] Figure 6 This is a control flowchart of the electronic expansion valve in the defrost mode of an air conditioner according to an embodiment of this application;

[0041] Figure 7 This is a flowchart illustrating the process of determining when an air conditioner exits defrost mode according to an embodiment of this application.

[0042] In the above figures: Indoor heat exchanger 1; Outdoor heat exchanger 2; Electronic expansion valve 3; Second temperature sensor 4; First temperature sensor 5; Compressor 6; Four-way valve 7. Detailed Implementation

[0043] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0044] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0045] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] In the following text, reference will be made to the appendix. Figure 1-7 The implementation methods of this application are described in detail.

[0048] The air conditioner of this application includes an indoor unit and an outdoor unit. The outdoor unit includes a compressor 6, an outdoor heat exchanger 2, and an electronic expansion valve 3. The indoor unit includes an indoor heat exchanger 1. The electronic expansion valve 3 may also be installed in the indoor unit.

[0049] Indoor heat exchanger 1 and outdoor heat exchanger 2 can function as a condenser and evaporator, respectively. When indoor heat exchanger 1 is used as a condenser, the air conditioner acts as a heater in heating mode, and outdoor heat exchanger 2 acts as an evaporator to release outdoor heat into the indoor space through refrigerant circulation, thus heating the indoor environment. When indoor heat exchanger 1 is used as an evaporator, the air conditioner acts as a cooler in cooling mode, and outdoor heat exchanger 2 acts as a condenser to release indoor heat into the outdoor environment through refrigerant circulation, thereby cooling the indoor space.

[0050] The compressor 6 includes an intake port, an exhaust port, and a compression chamber communicating with the intake port and the exhaust port, so that the refrigerant entering the compression chamber from the intake port is compressed by the compressor 6 and discharged from the exhaust port. The compressor 6 is used to provide the power for the flow of refrigerant in the vapor compression cycle.

[0051] The electronic expansion valve 3 is connected between the indoor heat exchanger 1 and the outdoor heat exchanger 2. After the refrigerant flows out of the condenser, it enters the electronic expansion valve 3 for expansion. The electronic expansion valve 3 throttles the high-temperature and high-pressure refrigerant liquid after the condensation process into a low-pressure refrigerant liquid, and then the low-pressure refrigerant liquid flows to the indoor heat exchanger 1.

[0052] The four-way valve 7 is connected to the indoor heat exchanger 1, the outdoor heat exchanger 2 and the compressor 6, and is used to switch the air conditioner between cooling and heating modes.

[0053] The indoor heat exchanger 1, the outdoor heat exchanger 2, the compressor 6, the four-way valve 7 and the electronic expansion valve 3 are connected by a pipeline, which includes a connecting pipe that connects the indoor heat exchanger 1 and the outdoor heat exchanger 2.

[0054] An air conditioner comprises a compressor 6, a condenser, an electronic expansion valve 3, and an evaporator that execute a refrigeration or heating cycle. The refrigeration and heating cycles include compression, condensation, expansion, and evaporation processes. By utilizing the heat absorption and release processes of the refrigerant, cooling or heating is provided to the indoor space, thereby regulating the indoor temperature.

[0055] Compressor 6 compresses the refrigerant gas into a high-temperature, high-pressure state and discharges the compressed refrigerant gas, which flows into the condenser. The condenser condenses the compressed, high-temperature, high-pressure gaseous refrigerant into a liquid refrigerant, and the heat is released to the surrounding environment through the condensation process.

[0056] Liquid refrigerant flowing from the condenser enters electronic expansion valve 3, which expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The low-pressure liquid refrigerant flowing from electronic expansion valve 3 enters the evaporator, where it absorbs heat and evaporates into a low-temperature, low-pressure refrigerant gas. This low-temperature, low-pressure refrigerant gas returns to compressor 6. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout this cycle, the air conditioner regulates the temperature of the indoor space.

[0057] The air conditioner also includes a first temperature sensor 5, a second temperature sensor 4, a third temperature sensor, and a defrost temperature sensor.

[0058] The first temperature sensor 5 is located on the pipeline connected to the exhaust port and is used to detect the exhaust temperature of the compressor 6.

[0059] The second temperature sensor 4 is installed on the refrigerant coil of the outdoor unit of the air conditioner and is used to detect the coil temperature of the outdoor heat exchanger 2. Alternatively, the second temperature sensor 4 can be installed on one of the condensing coils in the middle of the condenser, and the temperature of one of the condensing coils in the middle of the condenser can be defined as the coil temperature of the heat exchanger.

[0060] The third temperature sensor is located on the outdoor unit of the air conditioner and is used to detect the outdoor ambient temperature.

[0061] The defrost temperature sensor is installed on the subcooled section of the condenser's main outlet pipe to detect the temperature of the subcooled section of the condenser's main outlet pipe. The temperature of the subcooled section of the condenser's main outlet pipe is defined as the defrost temperature.

[0062] The air conditioner also includes a controller. A first temperature sensor 5, a second temperature sensor 4, a third temperature sensor, and a defrost temperature sensor are all electrically connected to the controller. The first temperature sensor 5 detects the exhaust temperature in real time and uploads it to the controller as an electrical signal. The second temperature sensor 4 detects the coil temperature of the outdoor heat exchanger 2 in real time and uploads it to the controller as an electrical signal. The third temperature sensor detects the outdoor ambient temperature in real time and uploads it to the controller as an electrical signal. The fourth temperature sensor detects the defrost temperature in real time and uploads it to the controller as an electrical signal.

[0063] The controller determines whether to put the air conditioner into defrost mode or exit defrost mode based on the real-time detected defrost temperature.

[0064] In defrost mode, outdoor heat exchanger 2 is used as a condenser, and indoor heat exchanger 1 is used as an evaporator. The controller adjusts the opening of electronic expansion valve 3 based on the current exhaust temperature, current coil temperature, and current outdoor ambient temperature, so that the liquid and gas two-phase region of the refrigerant in the coil of outdoor heat exchanger 2 gradually moves to the middle and rear section of the coil of outdoor heat exchanger 2 as the defrost time changes, thereby gradually improving the defrost efficiency of the middle and rear section of the coil of outdoor heat exchanger 2.

[0065] The controller is configured to obtain the defrost entry temperature based on the outdoor ambient temperature through a second logic operation. When the defrost temperature detected by the defrost sensor in real time reaches the defrost entry temperature, the controller controls the air conditioner to enter the defrost mode.

[0066] The second logic is set as follows: T defin =F*T outdoor +G, where: T defin This is the defrost entry temperature; F is a constant, the value of which is confirmed based on the debugging data; G is a constant, the value of which is confirmed based on the debugging data; T outdoor It is the outdoor ambient temperature, which is measured in real time by a third temperature sensor.

[0067] The defrost entry temperature is positively correlated with the outdoor ambient temperature. The higher the outdoor ambient temperature, the higher the defrost entry temperature; the lower the outdoor ambient temperature, the lower the defrost entry temperature.

[0068] The controller is also configured to determine the defrost frequency of compressor 6 in defrost mode based on the detected outdoor ambient temperature. When operating in defrost mode, compressor 6 operates at a fixed defrost frequency determined based on the outdoor ambient temperature.

[0069] The controller has a pre-installed database that stores data, with different outdoor ambient temperatures mapped to corresponding defrost frequencies. Different outdoor ambient temperatures correspond to different defrost frequencies. The lower the outdoor ambient temperature in the database, the higher the corresponding defrost frequency. This prevents prolonged defrosting times or incomplete defrosting caused by low outdoor ambient temperatures and low defrost frequencies.

[0070] In this embodiment, the higher the outdoor temperature, the lower the defrosting frequency, which can prevent the condensing pressure from overshooting due to the high defrosting frequency. This would cause the coil temperature of the outdoor heat exchanger 2 to rise too quickly, resulting in the defrosting temperature detected by the defrosting sensor reaching the defrosting exit temperature, thus causing the defrosting to stop before it is completely clean.

[0071] The controller is also configured to: derive the target defrost superheat (DSH) based on the outdoor ambient temperature, defrost frequency, and defrost running time in defrost mode through a first logical operation. def By increasing the opening of the electronic expansion valve 3, the actual defrosting superheat is made to reach the target defrosting superheat DSH. def The defrost superheat is defined as the difference between the exhaust temperature and the coil temperature of the outdoor heat exchanger 2. In defrost mode, the exhaust temperature is higher than the coil temperature of the outdoor heat exchanger 2.

[0072] At the start of defrosting, the exhaust temperature is high, and the opening of electronic expansion valve 3 is relatively small. At this time, the target defrosting superheat DSH is... def The two-phase region of gaseous and liquid refrigerants, which releases the most heat in outdoor heat exchanger 2, is located at the front of the refrigerant flow path. This region can quickly melt the frost in the front of the refrigerant flow path into water, simultaneously flushing away frost in the middle and rear sections of the refrigerant flow path and filling the gaps between the frost layer and the fins, increasing the contact area between the frost layer and the refrigerant coil, and improving the subsequent defrosting heat transfer efficiency. At this time, the middle and rear sections of the refrigerant flow path mainly rely on single-phase heat exchange with liquid refrigerant. Because the enthalpy of liquid refrigerant is lower at the same temperature, the heat release of liquid refrigerant in the middle and rear sections of the refrigerant flow path is relatively small, resulting in slower defrosting efficiency.

[0073] With the defrosting mode in operation, the opening of the electronic expansion valve 3 is increased, reducing the refrigerant flow path resistance and the exhaust temperature, thereby lowering the target defrosting superheat DSH. def At this point, the exhaust temperature is moderate, and the two-phase regions of gaseous and liquid states, which release the most heat, are located in the front and middle sections of the flow path. Lowering the exhaust temperature reduces the temperature difference between the front section of the refrigerant flow path and the outdoor ambient temperature, thereby reducing heat loss in the front section and conserving heat to improve defrosting efficiency in the middle and rear sections. At this point, the rear section of the flow path primarily relies on single-phase heat exchange with liquid refrigerant. Since the enthalpy of liquid refrigerant is lower at the same temperature, the heat release of liquid refrigerant in the rear section is less, resulting in slower defrosting efficiency.

[0074] As the defrost mode continues to operate, the opening of the electronic expansion valve 3 will continue to increase, thereby further reducing the target defrost superheat DSH. def At this point, the exhaust temperature continues to decrease, and the two-phase region of gaseous and liquid phases, which releases the most heat, expands to the front, middle, and rear sections of the flow path. This decrease in exhaust temperature reduces heat loss in the front and middle sections of the refrigerant flow path, thus preserving heat and improving defrosting efficiency in the rear section. Since the enthalpy of gaseous refrigerant at the same temperature is higher than that of liquid refrigerant at the same temperature, and gaseous refrigerant releases more heat at the same temperature, the expansion of the two-phase region of gaseous and liquid phases to the rear section of the flow path accelerates the defrosting rate in that section.

[0075] The first logic includes: obtaining the superheat factor by operating the defrost frequency with constants A and B; obtaining the outdoor ambient temperature factor by operating the outdoor ambient temperature with constants C and D; obtaining the defrost factor by operating the defrost time with constant E; and calculating the target defrost superheat by subtracting the defrost factor from the product of the superheat factor and the room ambient temperature factor.

[0076] Specifically, the first logic is set as follows: Where A, B, C, D, and E are constants, and these constants remain fixed under different outdoor ambient temperatures; Fre aim This refers to the defrost frequency in defrost mode; T outdoor This refers to the outdoor ambient temperature in defrost mode; t def This is the defrosting operation time.

[0077] Among them, Fre aim ×A+B is the overheat factor. The defrosting frequency is positively correlated with the overheat factor, and the defrosting frequency is positively correlated with the target defrosting overheat.

[0078] This refers to the outdoor ambient temperature factor. There is a positive correlation between the outdoor ambient temperature and the outdoor ambient temperature factor, as well as a positive correlation between the outdoor ambient temperature and the target defrost superheat. The calculated value of the outdoor ambient temperature factor differs under different outdoor ambient temperatures, while the calculated value is the same under the same outdoor ambient temperature. When the outdoor ambient temperature is too low, the target defrost superheat is lower. This prevents the electronic expansion valve 3 from opening too narrowly due to a higher target defrost superheat setting, which could lead to excessive throttling of the system, causing the evaporation pressure to fall below the specified lower pressure limit of the compressor 6, thus affecting the lifespan of the compressor 6 and the overall reliability of the machine.

[0079] Defrosting time is positively correlated with defrosting factor, while defrosting time is negatively correlated with target defrosting overheat.

[0080] t def*E represents the defrosting time factor. The longer the defrosting time, the higher the value of the defrosting time factor, and the higher the target defrosting overheat level (DSH). def The smaller the value, the better. Defrosting mode is a gradual process over time. From the start to the end of defrosting mode, the frost layer on the outside of the condenser coil of outdoor heat exchanger 2 gradually diminishes from the front of the refrigerant flow path to the rear. The defrosting time factor mainly controls the target defrosting superheat DSH. def As the defrosting time decreases, the opening of the electronic expansion valve 3 is increased with the defrosting time, thereby increasing the refrigerant circulation flow rate of the system. This ensures that the gaseous and liquid refrigerant two-phase regions are matched with the defrosting progress of the front, middle and rear sections of the refrigerant flow path, thus accelerating the defrosting efficiency.

[0081] When the defrost mode is running, the opening of the electronic expansion valve 3 is increased in stages within a preset time period during the defrost mode.

[0082] The preset time period can be set to one minute. Within the first minute, the opening of the electronic expansion valve 3 increases in stages. That is, there are multiple stages within one minute, and the electronic expansion valve 3 performs an adjustment and detection cycle within each stage. The adjustment and detection cycle includes increasing the opening of the electronic expansion valve 3 by a preset degree. After increasing the opening by a preset degree, the real-time exhaust temperature and real-time coil temperature are detected to obtain the real-time defrost superheat, and to determine whether the real-time defrost superheat has reached the target defrost superheat.

[0083] When the real-time defrost overheat does not reach the target defrost overheat, the electronic expansion valve 3 continues to perform an adjustment and detection cycle in the next segment within the first minute, so that after multiple adjustment and detection cycles within the first minute, the real-time defrost overheat reaches the target defrost overheat, and the electronic expansion valve 3 maintains the current opening degree within the first minute.

[0084] When the real-time defrosting overheat reaches the target defrosting overheat, the electronic expansion valve 3 maintains its current opening for a preset time period until the opening of the electronic expansion valve 3 is increased in stages within the second minute.

[0085] The segmented increase in the opening of the electronic expansion valve 3 allows the real-time defrosting superheat to gradually approach the target defrosting superheat. This prevents the real-time defrosting superheat from falling below the target defrosting superheat due to an excessive increase in the opening of the electronic expansion valve 3, thus avoiding any impact on defrosting efficiency.

[0086] When the defrost sensor detects that the defrost temperature has reached the defrost exit temperature, the controller controls the air conditioner to exit defrost mode. After exiting defrost mode, the air conditioner resumes normal heating mode operation.

[0087] An outdoor fan is installed inside the outdoor unit of the air conditioner. When the defrost mode is running, the outdoor fan stops to avoid increasing the heat loss of the refrigerant flow path.

[0088] During the defrosting process of this invention, the controller determines the defrosting frequency of the compressor 6 in defrosting mode based on the outdoor ambient temperature, and sets the target defrosting superheat (DSH) based on the outdoor ambient temperature, defrosting frequency, and defrosting time. def Corrections are made. By adjusting and increasing the opening of the electronic expansion valve 3 in defrost mode, the actual defrost superheat reaches the target defrost superheat. This causes the refrigerant two-phase zone of the refrigerant coil in the outdoor heat exchanger 2 to gradually move from the front side to the rear side of the refrigerant flow path. As a result, most of the heat during the defrost process is used for defrosting, reducing heat loss in the refrigerant flow path and improving defrost efficiency.

[0089] In some embodiments, after the defrosting mode is started, the opening of the electronic expansion valve 3 is reduced to quickly increase the exhaust temperature. The high exhaust temperature is used to quickly remove the frost layer in the front section of the refrigerant flow path of the outdoor heat exchanger 2. At this time, the defrosted water can flush the frost layer below and fill the gap between the frost layer and the fins, increasing the contact area between the frost layer and the refrigerant flow path to accelerate defrosting.

[0090] As the defrosting time increases in defrosting mode, the frost layer at the front of the refrigerant flow path of outdoor heat exchanger 2 shifts to the middle and rear of the refrigerant flow path. The opening degree of electronic expansion valve 3 increases with the defrosting time, which can reduce the exhaust temperature and decrease the target defrosting superheat DSH. def The difference between the actual defrosting superheat and the actual superheat reduces heat loss from heat exchange between the refrigerant flow path and the air, causing the two-phase region in the refrigerant flow path to shift to the middle and rear sections. The two-phase region then performs defrosting by releasing heat in these middle and rear sections. Since the enthalpy of gaseous refrigerant is higher than that of liquid refrigerant at the same temperature, and gaseous refrigerant releases more heat at the same temperature, the expansion of the gaseous and liquid two-phase region to the middle and rear sections of the flow path accelerates the defrosting rate in those sections.

[0091] Compared to related defrosting technologies, the defrosting mode in this embodiment allows for a faster expansion of the gaseous and liquid two-phase regions in the refrigerant coil of the outdoor heat exchanger 2. In outdoor low-temperature and high-humidity scenarios, the defrosting time is significantly shorter than conventional defrosting modes, resulting in a significantly improved heating cycle capacity.

[0092] In this embodiment's defrosting mode, at the start of defrosting, the exhaust temperature is high, and the opening of the electronic expansion valve 3 is relatively small. At this time, the target defrosting superheat DSH is... defThe two-phase region of gaseous and liquid refrigerants, which releases the most heat in outdoor heat exchanger 2, is located at the front of the refrigerant flow path. This region can quickly melt the frost in the front of the refrigerant flow path into water, simultaneously flushing away frost in the middle and rear sections of the refrigerant flow path and filling the gaps between the frost layer and the fins, increasing the contact area between the frost layer and the refrigerant coil, and improving the subsequent defrosting heat transfer efficiency. At this time, the middle and rear sections of the refrigerant flow path mainly rely on single-phase heat exchange with liquid refrigerant. Because the enthalpy of liquid refrigerant is lower at the same temperature, the heat release of liquid refrigerant in the middle and rear sections of the refrigerant flow path is relatively small, resulting in slower defrosting efficiency.

[0093] With the defrosting mode in operation, the opening of the electronic expansion valve 3 is increased, reducing the refrigerant flow path resistance and the exhaust temperature, thereby lowering the target defrosting superheat DSH. def At this point, the exhaust temperature is moderate, and the two-phase regions of gaseous and liquid states, which release the most heat, are located in the front and middle sections of the flow path. Lowering the exhaust temperature reduces the temperature difference between the front section of the refrigerant flow path and the outdoor ambient temperature, thereby reducing heat loss in the front section and conserving heat to improve defrosting efficiency in the middle and rear sections. At this point, the rear section of the flow path primarily relies on single-phase heat exchange with liquid refrigerant. Since the enthalpy of liquid refrigerant is lower at the same temperature, the heat release of liquid refrigerant in the rear section is less, resulting in slower defrosting efficiency.

[0094] As the defrost mode continues to operate, the opening of the electronic expansion valve 3 will continue to increase, thereby further reducing the target defrost superheat DSH. def At this point, the exhaust temperature continues to decrease, and the two-phase region of gaseous and liquid phases, which releases the most heat, expands to the front, middle, and rear sections of the flow path. This decrease in exhaust temperature reduces heat loss in the front and middle sections of the refrigerant flow path, thus preserving heat and improving defrosting efficiency in the rear section. Since the enthalpy of gaseous refrigerant at the same temperature is higher than that of liquid refrigerant at the same temperature, and gaseous refrigerant releases more heat at the same temperature, the expansion of the two-phase region of gaseous and liquid phases to the rear section of the flow path accelerates the defrosting rate in that section.

[0095] In this embodiment, R32 refrigerant is used as an example. The enthalpy of R32 gaseous refrigerant at 20°C is greater than that of liquid refrigerant at 20°C.

[0096] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An air conditioner, characterized in that, include: An indoor unit for an air conditioner, which includes an indoor heat exchanger; An outdoor unit for an air conditioner includes an outdoor heat exchanger and a compressor. The compressor includes an air intake, an air exhaust, and a compression chamber communicating with the air intake and the air exhaust, so that refrigerant entering the compression chamber from the air intake is compressed by the compressor and discharged from the air exhaust. An electronic expansion valve is connected between the indoor heat exchanger and the outdoor heat exchanger to throttle the high-temperature, high-pressure refrigerant liquid after passing through the outdoor heat exchanger into a low-pressure refrigerant liquid. A first temperature sensor is installed on a pipe connected to the exhaust port to detect the exhaust temperature of the compressor. The second temperature sensor is installed on the refrigerant coil of the outdoor heat exchanger and is used to detect the coil temperature of the outdoor heat exchanger. The third temperature sensor is installed on the outdoor unit of the air conditioner and is used to detect the outdoor ambient temperature; The defrost superheat is defined as the difference between the exhaust temperature and the coil temperature of the outdoor heat exchanger. The controller is configured as follows: The defrosting frequency of the compressor in defrosting mode is determined based on the detected outdoor ambient temperature. When the defrost mode is running, the compressor operates at the defrost frequency; The target defrost overheat is determined by a first logical operation based on the outdoor ambient temperature, defrost frequency, and defrost operation time under the defrost mode. ; By controlling the opening of the electronic expansion valve to increase, the actual defrost superheat is made to reach the target defrost superheat. .

2. The air conditioner according to claim 1, characterized in that, The first logic is set as follows: The superheat factor is obtained by calculating the defrosting frequency with constants A and B. The outdoor ambient temperature factor is obtained by calculating the outdoor ambient temperature with constants C and D. The defrosting factor is obtained by calculating the defrosting running time and the constant E. The target defrost superheat is calculated by subtracting the defrost factor from the product of the superheat factor and the outdoor ambient temperature factor.

3. The air conditioner according to claim 1, characterized in that, The first logic is set as follows: ； Where A, B, C, D, and E are constants. It is the defrosting frequency in the defrosting mode; Toutdoor is the outdoor ambient temperature in the defrosting mode; This refers to the defrosting operation time.

4. The air conditioner according to claim 1, characterized in that, When the defrosting mode is activated and the opening of the electronic expansion valve is increased, the opening of the electronic expansion valve increases in segments within a preset time period.

5. The air conditioner according to claim 4, characterized in that, After the electronic expansion valve increases the preset opening degree in each segment, it detects whether the real-time defrost overheat degree has reached the target defrost overheat degree. When the real-time defrosting overheat does not reach the target defrosting overheat, the electronic expansion valve increases the preset opening degree in the next segment of the preset time period; When the real-time defrost overheat reaches the target defrost overheat, the electronic expansion valve maintains its current opening degree for the preset time period.

6. The air conditioner according to claim 1, characterized in that, The controller has a pre-set database, in which different outdoor ambient temperatures are mapped to corresponding defrosting frequencies; the lower the outdoor ambient temperature in the database, the higher the defrosting frequency.

7. The air conditioner according to claim 1, characterized in that, The outdoor unit of the air conditioner is equipped with an outdoor fan, which stops operating when the defrost mode is running.

8. The air conditioner according to claim 2, characterized in that, The defrosting frequency is positively correlated with the overheating factor, and the defrosting frequency is positively correlated with the target defrosting overheating.

9. The air conditioner according to claim 2, characterized in that, The outdoor ambient temperature is positively correlated with the outdoor ambient temperature factor, and the outdoor ambient temperature is positively correlated with the target defrost overheat.

10. The air conditioner according to claim 2, characterized in that, The defrosting operation time is positively correlated with the defrosting factor, and the defrosting operation time is negatively correlated with the target defrosting overheat.

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