Outdoor unit, defrosting control method and controller

Abstract

The invention discloses an outdoor unit, a defrosting control method and a controller, the outdoor unit comprises an outdoor fan, an outdoor heat exchanger, an electric heating device, a water pan and the controller, the surface of the outdoor heat exchanger is coated with a super-hydrophobic coating, the water pan is arranged below the outdoor heat exchanger and the outdoor fan, the electric heating device is arranged above the water pan, and the controller is connected with the controller. The controller is used for starting the electric heating device and the outdoor fan in a defrosting mode, when frost on the surface of the outdoor heat exchanger coated with the super-hydrophobic coating falls off, the falling frost is pulled away towards the outdoor fan through rotation of the outdoor fan, the frost passes through the electric heating device arranged between the outdoor heat exchanger and the outdoor fan, and the frost is removed from the outdoor heat exchanger through the electric heating device arranged between the outdoor heat exchanger and the outdoor fan. When the frost is heated, the electric heating device increases the temperature of the frost, so that the heated frost falls into the water pan of the outdoor unit under the influence of gravity, the temperature of water in the water pan is prevented from being too low, and the ice accumulation condition of the water pan is effectively relieved.

Description

Technical Field

[0001] The present application relates to the technical field of air-conditioning systems, and in particular to an outdoor unit, a defrosting control method and a controller. Background Art

[0002] When the air conditioning system is running in heating mode, the outdoor heat exchanger of the air conditioning system will gradually frost, and the air conditioning system needs to run the defrost mode regularly to prevent severe frost on the outdoor heat exchanger and affect the normal operation of the air conditioning system. Since the defrost mode does not heat the room, the defrost mode needs to be run more frequently under low-temperature heating conditions, which will inevitably affect the indoor temperature and cause poor human comfort.

[0003] In order to deal with the problem of frequent defrosting, some outdoor heat exchangers are coated with super-hydrophobic coatings on the heat exchange fins, which can reduce the water and frost attached to the heat exchange fins, effectively extend the frosting cycle of the outdoor heat exchanger under low-temperature heating conditions, and shorten the defrosting time. However, in actual applications, the frost on the heat exchange fins coated with super-hydrophobic coatings will fall off in blocks into the water tray of the outdoor unit, causing the frost in the water tray to accumulate and thicken, solidify into ice, and gradually deteriorate the frost suppression performance of the super-hydrophobic coating, resulting in a decrease in the heating efficiency of the air-conditioning system, and may even interfere with the fan impeller of the outdoor unit, causing motor failure. Summary of the invention

[0004] The embodiments of the present application provide an outdoor unit, a defrost control method and a controller, which can effectively prevent ice from forming in a water receiving pan of the outdoor unit and ensure the normal operation of the air-conditioning system.

[0005] In a first aspect, an embodiment of the present application provides an outdoor unit, comprising:

[0006] Outdoor fan;

[0007] An outdoor heat exchanger, wherein a surface of the outdoor heat exchanger is coated with a super-hydrophobic coating;

[0008] A water receiving tray is arranged below the outdoor heat exchanger and the outdoor fan;

[0009] An electric heating device is arranged above the water receiving tray;

[0010] The controller is used to start the electric heating device and the outdoor fan in the defrost mode so that the frost on the outdoor heat exchanger falls off and is heated by the electric heating device.

[0011] In some embodiments, the electric heating device includes a plurality of electric heating tubes, and the plurality of electric heating tubes are evenly distributed between the outdoor heat exchanger and the outdoor fan.

[0012] In some embodiments, the outdoor heat exchanger includes heat exchange fins and a refrigerant coil, the superhydrophobic coating is coated on the heat exchange fins, the refrigerant coil includes a heat exchanger refrigerant pipe and a chassis refrigerant pipe, the heat exchanger refrigerant pipe passes through the heat exchange fins, and the chassis refrigerant pipe passes through the water receiving pan.

[0013] In a second aspect, an embodiment of the present application provides a defrost control method, which is applied to the outdoor unit as described in the first aspect, and the defrost control method includes:

[0014] In the defrosting mode, the electric heating device and the outdoor fan are started to make the frost on the outdoor heat exchanger fall off and be heated by the electric heating device.

[0015] In some embodiments, starting the electric heating device and the outdoor fan includes:

[0016] Starting the electric heating device with a preset power, wherein the preset power is greater than 0;

[0017] The outdoor fan is started at a preset first speed, where the preset first speed is greater than 0.

[0018] In some embodiments, the outdoor heat exchanger is connected to the indoor heat exchanger of the indoor unit through a refrigerant pipeline, and an electronic expansion valve is provided in the refrigerant pipeline; before starting the electric heating device and the outdoor fan, the defrost control method further includes:

[0019] Before entering the defrost mode, reducing the speed of the indoor fan of the indoor unit to a preset second speed;

[0020] After reducing the operating frequency of the compressor to the first operating frequency, the opening of the electronic expansion valve is increased.

[0021] In some embodiments, a four-way valve is further provided in the refrigerant pipeline; before and after entering the defrost mode, the valve state of the four-way valve does not change.

[0022] In some embodiments, when the defrost mode is not entered, the outdoor fan is started at a preset third speed, and the preset third speed is greater than the preset first speed.

[0023] In some embodiments, a temperature sensor is provided in the water receiving tray; and the defrosting control method further comprises:

[0024] Acquiring a detected temperature of the temperature sensor;

[0025] When the detected temperature is less than or equal to a preset first temperature, the defrost mode is entered, and the preset first temperature is determined according to the outdoor ambient temperature.

[0026] In some embodiments, after entering the defrost mode, the defrost control method further includes:

[0027] When the outdoor ambient temperature is greater than 0 degrees Celsius and the detected temperature is greater than the preset second temperature, or when the outdoor ambient temperature is less than 0 degrees Celsius and the absolute value of the detected temperature is less than the preset third temperature, the electric heating device is turned off and the defrost mode is exited.

[0028] In a third aspect, an embodiment of the present application provides a controller comprising at least one processor and a memory for communicating with the at least one processor; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the defrost control method as described in the embodiment of the second aspect.

[0029] The outdoor unit, defrost control method and controller of the embodiments of the present application have at least the following beneficial effects: in the defrost mode, frost on the surface of the outdoor heat exchanger coated with the super-hydrophobic coating will fall off, and the fallen frost will be drawn toward the outdoor fan by the rotation of the outdoor fan, so that the frost passes through the electric heating device arranged between the outdoor heat exchanger and the outdoor fan, and the electric heating device increases the temperature of the frost. In this way, the heated frost falls into the water receiving tray of the outdoor unit under the influence of gravity, avoiding the temperature of the water in the water receiving tray from being too low, and effectively alleviating the ice accumulation in the water receiving tray.

[0030] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a structural schematic diagram of an air conditioning system provided in an embodiment of the present application;

[0032] Figure 2 is a flow chart of starting an electric heating device and an outdoor fan provided in an embodiment of the present application;

[0033] Figure 3 This is a flow chart before starting the electric heating device and the outdoor fan provided in an embodiment of the present application;

[0034] Figure 4 is a timing diagram of the defrost control method provided in an embodiment of the present application;

[0035] Figure 5 is a flow chart for confirming entering the defrost mode provided by an embodiment of the present application;

[0036] Figure 6It is a flowchart of a specific example of the defrost control method provided in an embodiment of the present application.

[0037] Reference numerals:

[0038] Outdoor fan 100;

[0039] Outdoor heat exchanger 200;

[0040] Electric heating device 300;

[0041] Heat exchanger refrigerant pipe 400; electronic expansion valve 410; four-way valve 420;

[0042] Chassis refrigerant pipe 500;

[0043] Compressor 600;

[0044] Indoor fan 700; Indoor heat exchanger 710;

[0045] Temperature sensor 800. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. In addition, the characteristics, operations or features described in the specification can be combined in any appropriate manner to form various implementation methods. At the same time, the steps or actions in the method description can also be replaced or adjusted in order in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the accompanying drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0047] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0048] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0049] With the improvement of people's living standards, air conditioners have entered thousands of households. In addition to requiring air conditioners to have good cooling and heating functions, people are also pursuing higher and higher comfort. Among them, the air conditioning system has problems of indoor temperature fluctuation and thermal expansion and contraction when performing the heating function.

[0050] When the air conditioning system is heating, as the outdoor ambient temperature drops, the evaporation temperature decreases, the suction specific volume increases, the unit volume capacity decreases, and the heating amount decays. When the air conditioning system is used for heating at an evaporation temperature below 0°C, the evaporator will gradually frost. As the amount of frost increases, the four-way valve 420 is usually used to switch the cooling mode for periodic defrosting. During the defrosting process, the indoor fan 700 stops running, stops hot air output, and the outdoor heat exchanger 200 is defrosted. The greater the outdoor ambient humidity, the more frequent the defrosting. Frequent defrosting of the air conditioning system is bound to cause a significant drop in indoor temperature, and the human body perceives poor comfort.

[0051] In order to cope with the problem of frequent defrosting, an existing technology is to coat the heat exchanger of the outdoor unit with a super-hydrophobic coating, which can effectively extend the frosting cycle of the outdoor heat exchanger 200 under low-temperature heating conditions, shorten the defrosting time, and improve the heating efficiency of the air-conditioning system and the user's thermal comfort experience.

[0052] However, the frost on the heat exchange fins coated with the super-hydrophobic coating will fall off in chunks into the water collection tray of the outdoor unit, causing the frost in the water collection tray to accumulate and thicken, solidify into ice, and gradually deteriorate the frost suppression performance of the super-hydrophobic coating, resulting in a decrease in the heating efficiency of the air-conditioning system, and may even interfere with the fan impeller of the outdoor unit, causing motor failure.

[0053] In order to solve the above-mentioned problems, the embodiments of the present application provide an outdoor unit, a defrost control method, a controller and an air-conditioning system.

[0054] The outdoor unit, defrost control method, controller and air conditioning system are described below in conjunction with the accompanying drawings:

[0055] Reference Figure 1 As shown, an outdoor unit provided in an embodiment of the present application includes: an outdoor fan 100, an outdoor heat exchanger 200, an electric heating device 300, a water receiving tray and a controller, the surface of the outdoor heat exchanger 200 is coated with a super hydrophobic coating, the water receiving tray is arranged below the outdoor heat exchanger 200 and the outdoor fan 100, and the electric heating device 300 is arranged above the water receiving tray, and the controller is used to start the electric heating device 300 and the outdoor fan 100 in the defrost mode, so that the frost on the outdoor heat exchanger 200 falls off and is heated by the electric heating device 300. The outdoor heat exchanger 200 can increase the heat exchange area in the form of heat exchange fins, so that the surface of the heat exchange fins on the outdoor heat exchanger 200 is coated with the above-mentioned super hydrophobic coating.

[0056] In the defrost mode, frost on the surface of the outdoor heat exchanger 200 coated with a super-hydrophobic coating will fall off, and the outdoor fan 100 will rotate to draw the fallen frost toward the outdoor fan 100, so that the frost passes through the electric heating device 300 arranged between the outdoor heat exchanger 200 and the outdoor fan 100. The electric heating device 300 increases the temperature of the frost. In this way, the heated frost falls into the water receiving tray of the outdoor unit under the influence of gravity, avoiding the temperature of the water in the water receiving tray from being too low, and effectively alleviating the ice accumulation in the water receiving tray.

[0057] In some embodiments, the electric heating device 300 includes a plurality of electric heating pipes, and the plurality of electric heating pipes are evenly distributed between the outdoor heat exchanger 200 and the outdoor fan 100. In the defrosting mode, the plurality of electric heating pipes are started. Since the plurality of electric heating pipes are evenly distributed between the outdoor heat exchanger 200 and the outdoor fan 100, the frost falling off from various places on the heat exchange fins can be heated and heated evenly. The plurality of electric heating pipes can ensure the heating effect of the frost. After being heated, the frost falls into the water receiving tray to avoid the water temperature in the water receiving tray being too low, and effectively alleviate the ice accumulation in the water receiving tray. It should be noted that the uniform distribution of the electric heating pipes is not limited. For example, the plurality of electric heating pipes can be evenly arranged horizontally or vertically between the outdoor heat exchanger 200 and the outdoor fan 100.

[0058] In some embodiments, the outdoor heat exchanger 200 further includes a refrigerant coil. Figure 1 As shown, the refrigerant coil includes a heat exchanger refrigerant tube 400 and a chassis refrigerant tube 500. The heat exchanger refrigerant tube 400 passes through the heat exchange fins, and the chassis refrigerant tube 500 passes through the water receiving tray. The heat exchanger refrigerant tube 400 mainly cooperates with the heat exchange fins to perform heat exchange, and the chassis refrigerant tube 500 is arranged at the inner or outer wall of the water receiving tray to provide heat for the water receiving tray to melt ice. During defrosting, one or more electric heating tubes of the electric heating device 300 are electrically heated, and the outdoor fan 100 extracts the frost that falls off the heat exchanger refrigerant tube 400, so that it passes near the electric heating tube of the electric heating device 300, and falls into the water receiving tray after being heated. At this time, the chassis refrigerant tube 500 in the water receiving tray is also heated, ensuring that the temperature of water or frost in the water receiving tray will not be too low to freeze.

[0059] In addition, an embodiment of the present application provides a defrost control method, which is applied to the outdoor unit as described above. The defrost control method includes but is not limited to the following steps:

[0060] Step S100 , in the defrost mode, the electric heating device 300 and the outdoor fan 100 are started to make the frost on the outdoor heat exchanger 200 fall off and be heated by the electric heating device 300 .

[0061] In the embodiment, in the defrost mode, the electric heating device 300 and the outdoor fan 100 are started, and the frost on the surface of the heat exchange fins coated with the super-hydrophobic coating will fall off. The outdoor fan 100 rotates to draw the fallen frost toward the outdoor fan 100, so that the frost passes through the electric heating device 300 arranged between the outdoor heat exchanger 200 and the outdoor fan 100. The electric heating device 300 increases the temperature of the frost. In this way, the heated frost falls into the water receiving tray of the outdoor unit under the influence of gravity, which prevents the water temperature in the water receiving tray from being too low, and effectively alleviates the ice accumulation in the water receiving tray.

[0062] It is understandable that the electric heating device 300 includes a plurality of electric heating tubes, which are evenly distributed between the outdoor heat exchanger 200 and the outdoor fan 100. In the defrosting mode, the plurality of electric heating tubes are started, and since the plurality of electric heating tubes are evenly distributed between the outdoor heat exchanger 200 and the outdoor fan 100, the frost falling off from various places on the heat exchange fins can be heated and heated evenly, thereby ensuring the heating effect of the frost.

[0063] It should be noted that in the defrost mode, after the electric heating device 300 is started, it can not only heat the frost falling off the surface of the heat exchange fins, but also heat the ice accumulated in the water tray, so that the ice accumulated in the water tray can melt quickly and prevent the ice from piling up in the water tray.

[0064] It can be understood that in the defrost mode, the electric heating device 300 works to increase the air temperature in the outdoor unit, and the outdoor fan 100 rotates to form hot air, which flows toward the air duct of the outdoor unit and can melt the tiny ice layer attached to the inner wall of the air duct of the outdoor unit.

[0065] Reference Figure 2 As shown, in some embodiments, step S100 starts the electric heating device 300 and the outdoor fan 100, including but not limited to the following steps:

[0066] Step S110, starting the electric heating device 300 with a preset power, the preset power being greater than 0;

[0067] Step S120, starting the outdoor fan 100 at a preset first speed, where the preset first speed is greater than 0.

[0068] In the embodiment, the electric heating device 300 is started with a preset power, and the purpose is to heat the frost falling off the heat exchange fins and the ice accumulated on the water receiving tray through the heat generated by the electric heating device 300, so as to achieve the effect of defrosting and melting ice. The outdoor fan 100 is started with a preset first speed, and the outdoor fan 100 rotates to draw the falling frost toward the outdoor fan 100, so that the frost passes through the electric heating device 300 disposed between the outdoor heat exchanger 200 and the outdoor fan 100, and the electric heating device 300 increases the temperature of the frost.

[0069] It is understandable that the preset first speed is lower than the speed of the outdoor fan 100 when the air-conditioning system is running in the heating mode. At the lower preset first speed, the frost that falls off passes through the electric heating device 300 at a lower speed, and the electric heating device 300 can fully heat the frost. In addition, when the outdoor fan 100 rotates at the preset first speed, the air-conditioning system can still run in the heating mode without stopping to switch to the defrost mode. In other words, during the heating process of the air-conditioning system, it can continue to defrost and ice, maintain the outdoor unit in a frost-free working state, and there is no need to stop the heating mode and switch to the defrost mode, which significantly improves the user experience and comfort.

[0070] In some embodiments, reference Figure 1 As shown, the outdoor heat exchanger 200 is connected to the indoor heat exchanger 710 of the indoor unit through a refrigerant pipeline, and an electronic expansion valve 410 is provided in the refrigerant pipeline; Figure 3 As shown, before starting the electric heating device 300 and the outdoor fan 100, the defrost control method also includes but is not limited to the following steps:

[0071] Step S130, before entering the defrost mode, reducing the speed of the indoor fan 700 of the indoor unit to a preset second speed;

[0072] Step S140, after reducing the operating frequency of the compressor 600 to a first operating frequency, the opening of the electronic expansion valve 410 is increased.

[0073] In the embodiment, refer to Figure 4 As shown, before entering the defrost mode, an instruction stage is provided. In the instruction stage, the speed of the indoor fan 700 of the indoor unit is reduced to the preset second speed. As the speed of the indoor fan 700 decreases, the temperature of the liquid refrigerant in the refrigerant pipeline is increased, and then the opening of the electronic expansion valve 410 is rapidly increased by reducing the frequency of the compressor 600 to the first operating frequency, so that the liquid refrigerant in the indoor unit side is quickly transferred. After entering the defrost mode, since the opening of the electronic expansion valve 410 is the largest, the outdoor fan 100 rotates at a lower preset first speed, so that the compression ratio of the air-conditioning system is reduced, and the refrigerant flow rate in the refrigerant pipeline is reduced. Due to the low refrigerant flow rate in the refrigerant pipeline, frost is slowly formed on the heat exchange fins, and the defrosting effect is good when the electric heating device 300 and the outdoor fan 100 are started. In addition, due to the early transfer of the liquid refrigerant in the indoor unit, the resident liquid refrigerant in the indoor unit is reduced, which significantly improves the two-phase refrigerant sound of the indoor unit caused by the flash evaporation of the liquid refrigerant resident in the indoor unit after the high pressure is reduced.

[0074] Reference Figure 1 As shown, in some embodiments, a four-way valve 420 is further provided in the refrigerant pipeline; before and after entering the defrost mode, the valve state of the four-way valve 420 does not change.

[0075] In the embodiment, a four-way valve 420 is provided in the refrigerant pipeline, and the switching between the cooling mode and the heating mode of the air-conditioning system is realized by switching the four-way valve 420. The conventional defrosting technology of the air-conditioning system usually uses the four-way valve 420 to switch the cooling mode for periodic defrosting. During the defrosting process, the indoor fan 700 stops running, stops the hot air output, and the outdoor heat exchanger 200 is defrosted. The higher the outdoor humidity, the more frequent the defrosting. Frequent defrosting of the air-conditioning system will inevitably cause a significant drop in the indoor temperature, and the human body will feel poor comfort. In this embodiment, the defrosting is not performed by switching the four-way valve 420. Refer to Figure 4 As shown, before and after the defrost mode, the valve state of the four-way valve 420 does not change. Since the outdoor fan 100 rotates at the preset first speed, the air-conditioning system can still operate in the heating mode without stopping to switch the defrost mode. That is, during the heating process of the air-conditioning system, it can continue to defrost and defrost, maintaining a frost-free working state of the outdoor unit, without stopping the heating mode to switch to the defrost mode, thereby significantly improving the user experience and comfort.

[0076] It is understandable that in the defrost mode, the air conditioning system still operates in the heating mode, the indoor heat exchanger 710 of the indoor unit is in a high temperature state, and the valve state of the four-way valve 420 does not change, that is, there is no need to switch to the cooling mode, thereby avoiding thermal expansion and contraction. In addition, before entering the defrost mode, the outdoor fan 700 is started at a preset third speed, and the preset third speed is greater than the preset first speed. When exiting the defrost mode or before the defrost cycle, the air conditioning system controls the outdoor fan 700 according to the preset third speed. The preset third speed can be the speed controlled in the normal mode of the air conditioning system, which is greater than the first preset speed in the defrost mode, because the first preset speed is set to be smaller or can be directly set to the minimum speed under the fan specifications.

[0077] In some embodiments, reference Figure 1 As shown, a temperature sensor 800 is provided in the water receiving tray, and the output end of the temperature sensor 800 is electrically connected to the input end of the controller; Figure 5 As shown, the defrost control method also includes but is not limited to the following steps:

[0078] Step S200, obtaining the detected temperature of the temperature sensor 800;

[0079] Step S300, when the detected temperature is less than or equal to a preset first temperature, enter the defrost mode, and the preset first temperature is determined according to the outdoor ambient temperature.

[0080] In this embodiment, the temperature at the water receiving tray is detected by the temperature sensor 800, and the temperature sensor 800 feeds back the detected temperature data to the controller. When the detected temperature is less than or equal to the preset first temperature, it is confirmed that ice is accumulated in the water receiving tray and the defrost mode is entered. In other words, by obtaining the detected temperature and further comparing the preset first temperature with the detected temperature, it is determined whether ice is accumulated in the water receiving tray. When it is confirmed that ice is accumulated in the water receiving tray, the defrost mode is entered and the water receiving tray can be defrosted in time.

[0081] It can be understood that the preset first temperature is determined according to the outdoor ambient temperature, and the specific calculation formula of the preset first temperature is as follows:

[0082] Ta1=0℃+△T1,

[0083] Wherein, Ta1 is a preset first temperature, ΔT1 is an entropy value, and ΔT1 is determined according to the outdoor ambient temperature.

[0084] In some embodiments, after entering the defrost mode, the defrost control method further includes but is not limited to the following steps:

[0085] Step S310, when the outdoor ambient temperature is greater than 0 degrees Celsius and the detected temperature is greater than the preset second temperature, or when the outdoor ambient temperature is less than 0 degrees Celsius and the absolute value of the detected temperature is less than the preset third temperature, turn off the electric heating device 300 and exit the defrost mode.

[0086] In this embodiment, by obtaining the outdoor temperature, when the outdoor ambient temperature is greater than 0 degrees Celsius and the detected temperature is greater than or equal to the preset second temperature, or when the outdoor ambient temperature is less than 0 degrees Celsius and the absolute value of the detected temperature is less than or equal to the preset third temperature, it is confirmed that the accumulated ice has melted, the electric heating device 300 is turned off, and the defrost mode is exited.

[0087] It should be noted that the calculation formula for the preset second temperature is as follows:

[0088] Ta2=Te+△T2,

[0089] Wherein, Ta2 is the preset second temperature, Te is the ambient temperature, and △T2 is the entropy value. It is understood that when the outdoor ambient temperature is greater than 0 degrees Celsius, and the detected temperature is greater than or equal to the preset second temperature, it indicates that under the action of the electric heating device 300, the temperature of the water receiving tray rises, the detected temperature is higher than the ambient temperature, and the difference between the detected temperature and the ambient temperature is greater than or equal to △T2, confirming that the ice accumulation has melted. It should be noted that △T2 can be determined based on empirical data.

[0090] It should be noted that the calculation formula for the preset third temperature is as follows:

[0091] Ta3=Te+△T3,

[0092] Wherein, Ta3 is the preset third temperature, Te is the ambient temperature, and △T3 is the entropy value. It is understood that when the outdoor ambient temperature is less than 0 degrees Celsius, and the absolute value of the detected temperature is less than or equal to the preset third temperature, it indicates that under the action of the electric heating device 300, the temperature of the water receiving tray rises, the detected temperature is higher than the ambient temperature, and the difference between the absolute value of the detected temperature and the ambient temperature is less than or equal to △T3, it is confirmed that the ice accumulation has melted. It should be noted that △T3 can be determined based on empirical data.

[0093] It is understandable that, referring to Figure 4 As shown, after exiting the defrost mode, the air-conditioning system recovers from the working state of synchronous operation of the heating mode and the defrost mode to the working state of normal operation of the heating mode, that is, the speed of the indoor fan 700, the speed of the outdoor fan 100, the frequency of the compressor 600 and the opening of the electronic expansion valve 410 are restored to the state of operating the heating mode alone before entering the defrost mode.

[0094] After the above description, this embodiment is also described using a specific example. Figure 6 As shown, the defrost control method specifically includes the following steps:

[0095] Step S1, obtaining the detected temperature Ta of the temperature sensor 800 in real time;

[0096] Step S2, when the detected temperature Ta is less than or equal to the preset first temperature Ta1, the rotation speed of the indoor fan 700 of the indoor unit is reduced to a preset second rotation speed;

[0097] Step S3, reducing the operating frequency of the compressor 600 to the first operating frequency and then increasing the opening of the electronic expansion valve 410;

[0098] Step S4, entering the defrost mode, starting the electric heating device 300 with a preset power;

[0099] Step S5, starting the outdoor fan 100 at a preset first speed;

[0100] Step S6, when the outdoor ambient temperature Te is greater than 0 degrees Celsius and the detected temperature Ta is greater than the preset second temperature Ta2, or when the outdoor ambient temperature Te is less than 0 degrees Celsius and the absolute value of the detected temperature Ta is less than the preset third temperature Ta3, turn off the electric heating device 300 and exit the defrost mode.

[0101] An embodiment of the present application also provides a controller, comprising at least one processor and a memory for communicating with the at least one processor; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the defrost control method as described in the above embodiment.

[0102] The embodiment of the present application also provides an air conditioning system, including the outdoor unit of the above embodiment or the controller of the above embodiment. It is understandable that the air conditioning system in this embodiment may include an indoor unit and an outdoor unit, which may be a household or commercial "one-to-one" air conditioner, or a multi-split air conditioner, commonly known as "one-to-many", that is, one outdoor unit is connected to multiple indoor units.

[0103] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed method above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0104] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. An outdoor unit, characterized in that: include: Outdoor fan; An outdoor heat exchanger, wherein a surface of the outdoor heat exchanger is coated with a super-hydrophobic coating; A water receiving tray is arranged below the outdoor heat exchanger and the outdoor fan; An electric heating device is arranged above the water receiving tray; The controller is used to start the electric heating device and the outdoor fan in the defrost mode so that the frost on the outdoor heat exchanger falls off and is heated by the electric heating device.

2. The outdoor unit according to claim 1, characterized in that: The electric heating device includes a plurality of electric heating tubes, and the plurality of electric heating tubes are evenly distributed between the outdoor heat exchanger and the outdoor fan.

3. The outdoor unit according to claim 1, characterized in that: The outdoor heat exchanger includes heat exchange fins and a refrigerant coil, the super-hydrophobic coating is coated on the heat exchange fins, the refrigerant coil includes a heat exchanger refrigerant pipe and a chassis refrigerant pipe, the heat exchanger refrigerant pipe passes through the heat exchange fins, and the chassis refrigerant pipe passes through the water receiving pan.

4. A defrosting control method, characterized in that: Applied to the outdoor unit according to any one of claims 1 to 3, the defrost control method comprises: In the defrosting mode, the electric heating device and the outdoor fan are started to make the frost on the outdoor heat exchanger fall off and be heated by the electric heating device.

5. The defrosting control method according to claim 4, characterized in that: The starting of the electric heating device and the outdoor fan comprises: Starting the electric heating device with a preset power, wherein the preset power is greater than 0; The outdoor fan is started at a preset first speed, where the preset first speed is greater than 0.

6. The defrosting control method according to claim 5, characterized in that: The outdoor heat exchanger is connected to the indoor heat exchanger of the indoor unit via a refrigerant pipeline, and an electronic expansion valve is arranged in the refrigerant pipeline; Before starting the electric heating device and the outdoor fan, the defrost control method further includes: Before entering the defrost mode, reducing the speed of the indoor fan of the indoor unit to a preset second speed; After reducing the operating frequency of the compressor to the first operating frequency, the opening of the electronic expansion valve is increased.

7. The defrosting control method according to claim 6, characterized in that: A four-way valve is also arranged in the refrigerant pipeline; before and after entering the defrost mode, the valve state of the four-way valve does not change.

8. The defrosting control method according to claim 5, characterized in that: The defrost control method further comprises: When the defrost mode is not entered, the outdoor fan is started at a preset third speed, and the preset third speed is greater than the preset first speed.

9. The defrosting control method according to claim 4, characterized in that: A temperature sensor is arranged in the water receiving tray; and the defrosting control method further comprises: Acquiring a detected temperature of the temperature sensor; When the detected temperature is less than or equal to a preset first temperature, the defrost mode is entered, and the preset first temperature is determined according to the outdoor ambient temperature.

10. The defrosting control method according to claim 9, characterized in that: After entering the defrost mode, the defrost control method further includes: When the outdoor ambient temperature is greater than 0 degrees Celsius and the detected temperature is greater than the preset second temperature, or when the outdoor ambient temperature is less than 0 degrees Celsius and the absolute value of the detected temperature is less than the preset third temperature, the electric heating device is turned off and the defrost mode is exited.

11. A controller, characterized in that It comprises at least one processor and a memory for communicating with the at least one processor; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the defrost control method as described in any one of claims 4 to 10.

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