Air conditioner outdoor unit

Abstract

The application discloses an air conditioner outdoor unit, and relates to the technical field of air conditioners. The air conditioner outdoor unit comprises a condenser, a compressor, an outdoor fan, a coil temperature sensor, an outdoor temperature sensor and a controller. The controller is configured to acquire an outdoor environment temperature detected by the outdoor temperature sensor and a coil temperature detected by the coil temperature sensor, and calculate a difference between the coil temperature and the outdoor environment temperature as a first difference. If the first difference is greater than or equal to a first set value, a target rotating speed of the outdoor fan is obtained according to a preset corresponding relationship between the coil temperature and the rotating speed of the outdoor fan. If the first difference is less than a second set value, a first rotating speed is taken as the target rotating speed of the outdoor fan. An absolute value of a difference between a current rotating speed of the outdoor fan and the first rotating speed is a first threshold value. If the first difference is less than the first set value and greater than or equal to the second set value, the current rotating speed of the outdoor fan is taken as the target rotating speed of the outdoor fan. The air conditioner outdoor unit provided by the application can realize stable control of the rotating speed of the outdoor fan under different outdoor environment temperature conditions, ensure the stability of heat dissipation of an outdoor heat exchanger, and thus ensure that the refrigerant pressure in the air conditioning system meets the safe operation condition.

Description

Technical Field

[0001] This application relates to the technical field of air conditioning, and more particularly to an outdoor unit for an air conditioner. Background Technology

[0002] During the circulation of refrigerant between the condenser, evaporator, and compressor, the liquid and gas phases transform into each other, transferring heat to achieve the cooling or heating operation of the air conditioning system.

[0003] In existing technologies, fans are typically installed around the condenser to increase airflow speed and thus improve the condenser's heat exchange efficiency. However, if the heat exchange between the condenser and the air is too large, the refrigerant temperature exiting the condenser will be too low, resulting in a low refrigerant pressure entering the evaporator. This could cause the evaporator to freeze or even result in incomplete evaporation of the refrigerant, leading to some liquid refrigerant flowing into the compressor and damaging it. Conversely, if the heat exchange between the condenser and the air is too small, the refrigerant temperature exiting the condenser will be too high, resulting in a high refrigerant temperature and pressure flowing into the evaporator. This weakens the evaporator's heat absorption capacity and leads to poor cooling performance. Furthermore, fluctuating heat exchange between the condenser and the air can cause unstable refrigerant temperatures flowing into the evaporator, leading to refrigerant pressure fluctuations in the system. This causes the compressor's operating frequency to fluctuate accordingly, reducing the air conditioner's lifespan and severely impacting the user experience. Summary of the Invention

[0004] To address the shortcomings of related technologies, this application provides an outdoor air conditioning unit that employs different control strategies to control the operation of the outdoor fan based on the temperature difference between the coil temperature of the outdoor heat exchanger and the outdoor ambient temperature. This enables stable control of the outdoor fan speed under different outdoor ambient temperature conditions, ensuring the stability of the heat dissipation of the outdoor heat exchanger and thus guaranteeing that the refrigerant pressure in the air conditioning system meets the safe operating conditions.

[0005] This application provides an outdoor unit for an air conditioner, comprising:

[0006] A condenser is used to exchange heat with outdoor air;

[0007] The compressor, together with the condenser and evaporator, forms a refrigerant circulation loop. The compressor is used to compress low-pressure refrigerant gas into high-pressure refrigerant gas and drive the refrigerant to flow in the refrigerant circulation loop.

[0008] An outdoor fan is used to drive air into contact with the condenser;

[0009] Coil temperature sensor is used to detect the coil temperature of the condenser;

[0010] Outdoor temperature sensor, used to detect outdoor ambient temperature;

[0011] The controller is connected to the outdoor fan, the coil temperature sensor, and the outdoor temperature sensor, respectively; the controller is configured as follows:

[0012] The outdoor ambient temperature detected by the outdoor temperature sensor and the coil temperature detected by the coil temperature sensor are obtained, and the difference between the coil temperature and the outdoor ambient temperature is calculated as the first difference.

[0013] If the first difference is greater than or equal to the first set value, the target speed of the outdoor fan is obtained according to the preset correspondence between the coil temperature and the outdoor fan speed.

[0014] If the first difference is less than the second set value, then the first speed is taken as the target speed of the outdoor fan; wherein, the absolute value of the difference between the current speed of the outdoor fan and the first speed is the first threshold.

[0015] If the first difference is less than the first set value and greater than or equal to the second set value, then the current speed of the outdoor fan is taken as the target speed of the outdoor fan.

[0016] This technical solution calculates the temperature difference between the coil temperature and the outdoor ambient temperature by measuring the difference between the coil temperature sensor and the outdoor temperature sensor. Based on the temperature difference between the coil temperature and the outdoor ambient temperature, different control strategies are adopted to control the operation of the outdoor fan to ensure the stability of the outdoor fan's operating speed, thereby ensuring the stability of the heat exchange of the outdoor heat exchanger and, consequently, the stability of the refrigerant pressure.

[0017] In some embodiments, the controller is further configured to: determine an upper limit and a lower limit for the outdoor fan speed based on a preset correspondence between outdoor ambient temperature and outdoor fan speed; if the target speed of the outdoor fan is less than the lower limit, control the outdoor fan to operate at the lower limit as the actual speed; if the target speed of the outdoor fan is greater than the upper limit, control the outdoor fan to operate at the upper limit as the actual speed; if the target speed of the outdoor fan is greater than or equal to the lower limit and less than or equal to the upper limit, control the outdoor fan to operate at the target speed as the actual speed.

[0018] This technical solution determines the upper and lower limits of the outdoor fan speed based on the outdoor ambient temperature, and uses these upper and lower limits to limit the target speed of the outdoor fan, in order to avoid instability and safety issues in the operation of the air conditioner caused by abnormal coil temperature.

[0019] In some embodiments, the controller is further configured to: when the first difference is greater than or equal to the first set value, if the difference between the current speed of the outdoor fan and the target speed is less than or equal to the second threshold, control the outdoor fan to operate at the target speed as the actual speed; if the difference between the current speed of the outdoor fan and the target speed is greater than the second threshold, control the outdoor fan to finally operate at the second speed as the actual speed; wherein the difference between the current speed of the outdoor fan and the second speed is the second threshold.

[0020] This technical solution limits the target speed of the outdoor fan determined based on the coil temperature. When the difference between the current speed of the outdoor fan and the target speed is greater than a second threshold, the outdoor fan is controlled to operate at the second speed as the target speed to prevent the target speed from being too large from causing the outdoor fan's rate of change to be too large.

[0021] In some embodiments, the controller is further configured to: when the first difference is greater than or equal to a first set value, if the target speed is less than the current speed of the outdoor fan, control the speed of the outdoor fan to change by at most a third threshold amount.

[0022] This technical solution limits the variation in outdoor fan speed to prevent unsafe operation of the outdoor fan and fluctuations in refrigerant pressure caused by large changes in outdoor fan speed.

[0023] In some embodiments, the controller is configured to: determine the trend of coil temperature change based on the detection value of the coil temperature sensor; and when the first difference is greater than or equal to a first set value, determine the operating speed of the outdoor fan based on the trend of coil temperature change and the detection value of the coil temperature sensor.

[0024] In this technical solution, determining the operating speed of the outdoor fan based on the temperature change trend of the coil can enable the outdoor fan to have a better heat dissipation effect on the outdoor heat exchanger.

[0025] In some embodiments, the controller is further configured to control the outdoor fan to continue operating at the current speed if the coil temperature shows a stable trend.

[0026] In this technical solution, the stable trend of the coil temperature indicates that the current speed of the outdoor fan meets the heat dissipation requirements of the outdoor heat exchanger. Controlling the outdoor fan to continue running at its current speed can maintain the current heat dissipation effect of the outdoor heat exchanger.

[0027] In some embodiments, when the first difference is the same, the target rotational speed determined when at least a portion of the coil temperature is changing in an upward trend is less than the target rotational speed determined when it is changing in a downward trend.

[0028] In this technical solution, the target speed determined when at least part of the coil temperature is changing upward is lower than the target speed determined when it is changing downward, so that the target speed of the outdoor fan can vary according to the different trends of coil temperature change, thereby enabling the outdoor fan to have a better heat dissipation effect.

[0029] In some embodiments, the controller is configured to determine the initial speed of the outdoor fan based on the outdoor ambient temperature detected by the outdoor temperature sensor when the outdoor unit of the air conditioner starts to run in cooling mode.

[0030] After controlling the outdoor fan to run at its initial speed for a preset time, the detection value of the coil temperature sensor is obtained.

[0031] This technical solution determines the initial speed of the outdoor fan based on the outdoor ambient temperature. After the outdoor fan has been running at the initial speed for a preset time, the detection value of the coil temperature sensor is then obtained to ensure the accuracy of the detection value of the coil temperature sensor.

[0032] In some embodiments, the controller is configured such that, among the initial speed of the outdoor fan, the upper limit of the outdoor fan speed, and the lower limit of the outdoor fan speed determined based on the detection value of the same outdoor temperature sensor, the initial speed of the outdoor fan is greater than or equal to the upper limit of the outdoor fan speed, and the initial speed of the outdoor fan is less than or equal to the lower limit of the outdoor fan speed.

[0033] In this technical solution, the parameters determined based on the detection value of the same outdoor temperature sensor include: the initial speed of the outdoor fan, the upper limit of the outdoor fan speed, and the lower limit of the outdoor fan speed. By making the initial speed of the outdoor fan greater than or equal to the upper limit of the outdoor fan speed and the initial speed of the outdoor fan less than or equal to the lower limit of the outdoor fan speed, the upper and lower limits can limit the target speed of the outdoor fan.

[0034] In addition, this application also provides an outdoor unit for an air conditioner, comprising:

[0035] A condenser is used to exchange heat with outdoor air;

[0036] The compressor, together with the condenser and evaporator, forms a refrigerant circulation loop. The compressor is used to compress low-pressure refrigerant gas into high-pressure refrigerant gas and drive the refrigerant to flow in the refrigerant circulation loop.

[0037] The outdoor fan is used to drive air to contact the condenser; the outdoor fan has multiple speed settings, each with a corresponding rotation speed.

[0038] Coil temperature sensor, used to detect coil temperature;

[0039] Outdoor temperature sensor, used to detect outdoor ambient temperature;

[0040] The controller is connected to the outdoor fan, the coil temperature sensor, and the outdoor temperature sensor, respectively; the controller is configured as follows:

[0041] Obtain the detection values ​​of the outdoor temperature sensor and the coil temperature sensor, and calculate the difference between the detection values ​​of the coil temperature sensor and the outdoor temperature sensor as the first difference.

[0042] Based on the relationship between the first difference and the set value, determine the initial target speed of the outdoor fan;

[0043] The initial target speed of the outdoor fan is corrected to obtain the final target speed of the outdoor fan, and the outdoor fan is controlled to continue operating at the final target speed.

[0044] This technical solution calculates the temperature difference between the coil temperature and the outdoor ambient temperature by measuring the difference between the coil temperature sensor and the outdoor temperature sensor. Based on this temperature difference, the initial target speed of the outdoor fan is determined and then adjusted to ensure the stability of the outdoor fan's operating speed, thereby ensuring the stability of the heat exchange of the outdoor heat exchanger and, consequently, the stability of the refrigerant pressure.

[0045] The outdoor unit of the air conditioner adopts different control strategies to control the operation of the outdoor fan based on the temperature difference between the coil temperature of the outdoor heat exchanger and the outdoor ambient temperature. It can achieve stable control of the outdoor fan speed under different outdoor ambient temperature conditions, ensure the stability of the heat dissipation of the outdoor heat exchanger, and thus ensure that the refrigerant pressure in the air conditioning system meets the safe operating conditions. Attached Figure Description

[0046] Figure 1 A schematic diagram of refrigerant flow is shown when the outdoor unit of an air conditioner is in cooling mode, according to some embodiments;

[0047] Figure 2 A schematic diagram of refrigerant flow is shown when the outdoor unit of an air conditioner is in heating mode, according to some embodiments.

[0048] Figure 3 An exemplary control flowchart for determining the target speed of the outdoor fan in the outdoor unit of an air conditioner according to this application is shown;

[0049] Figure 4 The control principle diagram for correcting the target speed in the outdoor unit of the air conditioner of this application is shown;

[0050] Figure 5 An exemplary flowchart is shown for determining the temperature change trend of the coil in the outdoor unit of an air conditioner according to this application;

[0051] Figure 6 An exemplary diagram illustrates the control principle of the outdoor unit of an air conditioner in this application, which uses upper and lower limits to correct the target speed.

[0052] Figure 7 An exemplary flowchart illustrates the control flow of the final speed of the outdoor fan in the outdoor unit of the air conditioner according to this application;

[0053] Figure 8 The working process of the outdoor unit of the air conditioner of this application is illustrated by way of example. Figure 1 ;

[0054] Figure 9 The working process of the outdoor unit of the air conditioner of this application is illustrated by way of example. Figure 2 ;

[0055] Figure 10 The illustration shows a schematic diagram of the upper limit and lower limit of the outdoor fan speed at different outdoor ambient temperatures in one embodiment of the outdoor unit of the air conditioner of this application;

[0056] Figure 11 An exemplary flowchart of the control flow of the outdoor fan speed in the outdoor unit of the air conditioner of this application is shown. Detailed Implementation

[0057] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0058] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0059] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0060] The terms “include” and “have”, and any variations thereof, are intended to cover but not exclusively include, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0061] The outdoor unit of the air conditioner provided in this application can have various implementation forms, such as the outdoor unit of a wall-mounted air conditioner, the outdoor unit of a cabinet air conditioner, etc.

[0062] An air conditioner includes an indoor unit, which is usually located indoors. The indoor unit includes an indoor heat exchanger, which is located indoors and used to exchange heat with indoor air, thereby heating or cooling the indoor environment.

[0063] An air conditioner includes an outdoor unit, which is usually located outdoors. The outdoor unit includes an outdoor heat exchanger, which is located outdoors and used to exchange heat with outdoor air.

[0064] An outdoor unit of an air conditioner includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger, which together form a refrigerant circulation loop. The compressor is used to compress the refrigerant from a low-pressure state to a high-pressure state and drive the refrigerant to circulate in the refrigerant circulation loop so that the indoor heat exchanger can cool or heat the indoor air.

[0065] like Figure 1 As shown, when the outdoor unit of the air conditioner cools the indoor environment, the outdoor heat exchanger acts as a condenser, and the indoor heat exchanger acts as an evaporator. The refrigerant, after being compressed by the compressor, flows into the outdoor heat exchanger to release heat, then flows into the indoor heat exchanger to absorb heat, and finally flows back into the compressor.

[0066] like Figure 2 As shown, when the outdoor unit of the air conditioner heats the indoor environment, the outdoor heat exchanger acts as the evaporator, and the indoor heat exchanger acts as the condenser. The refrigerant, after being compressed by the compressor, flows into the indoor heat exchanger to release heat, then flows into the outdoor heat exchanger to absorb heat, and finally flows back into the compressor.

[0067] When an air conditioner is running in cooling mode, the outdoor heat exchanger exchanges heat with the outdoor air, causing the temperature of the refrigerant flowing out of the outdoor heat exchanger to decrease. When the outdoor heat exchanger exchanges a large amount of heat with the outdoor air, the temperature of the refrigerant flowing out of the outdoor heat exchanger is low. Correspondingly, the temperature of the refrigerant flowing into the indoor heat exchanger is also low. More heat is required for the refrigerant to evaporate in the indoor heat exchanger, making the indoor heat exchanger prone to freezing. On the other hand, if the indoor heat exchanger does not absorb enough heat, the refrigerant inside the indoor heat exchanger will not evaporate completely, causing some liquid refrigerant to flow into the compressor, which can easily damage the compressor.

[0068] When the amount of heat exchanged between the outdoor heat exchanger and the outdoor air is small, the temperature of the refrigerant flowing out of the outdoor heat exchanger is high, and the temperature of the refrigerant flowing into the indoor heat exchanger is correspondingly high. The amount of heat required for the refrigerant to evaporate in the indoor heat exchanger is small, and the amount of heat exchanged between the indoor heat exchanger and the indoor air is small, so the temperature reduction effect cannot be achieved.

[0069] Furthermore, when the refrigerant temperature is low, the refrigerant pressure is also relatively low, and when the refrigerant temperature is high, the refrigerant pressure is also relatively high. If the heat exchange between the outdoor heat exchanger and the outdoor air is inconsistent and fluctuates, it can easily lead to fluctuations in the refrigerant pressure within the refrigerant circulation loop. The compressor's operating frequency will also fluctuate accordingly, which not only reduces the lifespan of the air conditioner but also results in a poor user experience.

[0070] In the prior art, the outdoor unit of an air conditioner includes an outdoor fan, which is used to increase the heat exchange effect of the outdoor heat exchanger; the operation of the outdoor fan causes air to circulate, thereby increasing the contact heat exchange effect between the air and the outdoor heat exchanger.

[0071] Outdoor fans have a significant impact on the heat exchange efficiency between outdoor heat exchangers and outdoor air. Generally, the higher the outdoor fan speed, the higher the airflow velocity, the greater the heat exchange between the outdoor heat exchanger and the outdoor air, and the better the heat exchange efficiency of the outdoor heat exchanger. Conversely, the lower the outdoor fan speed, the lower the airflow velocity, the less heat exchange between the outdoor heat exchanger and the outdoor air, and the worse the heat exchange efficiency of the outdoor heat exchanger.

[0072] In this application, when the air conditioner cools the indoor environment, the speed of the outdoor fan is adjusted and controlled to ensure the stability of heat exchange between the outdoor heat exchanger and the outdoor air, thereby preventing refrigerant pressure fluctuations and thus preventing unstable compressor operating frequency.

[0073] If, under the same outdoor ambient temperature, the coil temperature of the outdoor heat exchanger is high and the temperature difference between the outdoor heat exchanger coil temperature and the outdoor ambient temperature is large, then the outdoor fan speed needs to be increased to enhance the heat exchange effect between the outdoor heat exchanger and the air, preventing the refrigerant temperature from becoming too high and thus ensuring stable refrigerant pressure. Conversely, if the coil temperature of the outdoor heat exchanger is low and the temperature difference between the outdoor heat exchanger coil temperature and the outdoor ambient temperature is small, then the outdoor fan speed needs to be reduced to decrease the heat exchange effect between the outdoor heat exchanger and the air, preventing the refrigerant from being excessively cooled and thus ensuring stable refrigerant pressure.

[0074] In this application, the operation of the outdoor fan is controlled based on two parameters: the outdoor ambient temperature and the coil temperature of the outdoor heat exchanger, so as to achieve effective control of the outdoor fan.

[0075] The outdoor unit of an air conditioner includes an outdoor temperature sensor, which is used to detect the outdoor ambient temperature.

[0076] The outdoor unit of an air conditioner includes a coil temperature sensor, which is used to detect the coil temperature of the outdoor heat exchanger.

[0077] In this application, the temperature difference between the coil temperature and the outdoor ambient temperature is obtained by calculating the difference between the detected value of the coil temperature sensor and the detected value of the outdoor temperature sensor. Based on the temperature difference between the coil temperature and the outdoor ambient temperature, different control strategies are adopted to control the operation of the outdoor fan to ensure the stability of the outdoor fan's operating speed, thereby ensuring the stability of the heat exchange of the outdoor heat exchanger and thus ensuring the stability of the refrigerant pressure.

[0078] The outdoor unit of the air conditioner includes a controller, which is connected to the outdoor temperature sensor, the coil temperature sensor and the outdoor fan.

[0079] like Figure 3 As shown, the controller is configured to: acquire the outdoor ambient temperature from the outdoor temperature sensor, acquire the coil temperature of the outdoor heat exchanger from the coil temperature sensor, and calculate the difference between the coil temperature sensor's detection value and the outdoor temperature sensor's detection value as a first difference T1; determine the target speed Vs of the outdoor fan based on the relationship between the first difference T1 and the first set value S1 and the second set value S2; and control the outdoor fan to operate at the target speed Vs.

[0080] It should be noted that when the air conditioner is in cooling mode, the coil temperature of the outdoor heat exchanger is higher than the outdoor ambient temperature. When the temperature difference between the coil and the outdoor ambient temperature is too large, the current speed Vt of the outdoor fan cannot meet the current heat dissipation requirements of the outdoor heat exchanger, and the outdoor fan speed needs to be increased. When the temperature difference between the coil and the outdoor ambient temperature is too small, the current speed Vt of the outdoor fan exceeds the current heat dissipation requirements of the outdoor heat exchanger, and the outdoor fan speed is too high, so the outdoor fan speed needs to be reduced. When the temperature difference between the coil and the outdoor ambient temperature is within a certain range, the current speed Vt of the outdoor fan meets the current heat dissipation requirements of the outdoor heat exchanger, and the outdoor fan can maintain its current speed Vt.

[0081] Specifically, the controller is configured to: if the first difference T1 is greater than or equal to the first set value S1, determine the target speed Vs of the outdoor fan based on the detection value of the coil temperature sensor. It should be noted that in this application, a pre-set correspondence between coil temperature and the target speed of the outdoor fan is established. Based on the detection value of the coil temperature sensor, the coil temperature can be obtained, and the target speed of the outdoor fan at that coil temperature can be determined.

[0082] The first difference T1 being greater than or equal to the first set value S1 indicates that the temperature difference between the coil and the outdoor ambient temperature is large, and the current speed Vt of the outdoor fan cannot meet the heat dissipation requirements. It is necessary to increase the speed of the outdoor fan to ensure the stability of the refrigerant pressure.

[0083] The controller is further configured to: if the first difference T1 is less than the second set value S2, take the first speed as the target speed Vs of the outdoor fan, and the difference between the first speed and the current speed Vt of the outdoor fan is the first threshold.

[0084] The first difference T1 being less than the second set value S2 indicates that the temperature difference between the coil and the outdoor ambient temperature is small, requiring a reduction in the outdoor fan speed to ensure stable refrigerant pressure.

[0085] The controller is further configured to: if the first difference T1 is less than the first set value S1 and greater than or equal to the second set value S2, control the outdoor fan to take the current speed Vt as the target speed Vs of the outdoor fan, and control the outdoor fan to continue operating at the current speed Vt.

[0086] The first difference T1 is less than the first set value S1 and greater than or equal to the second set value S2, indicating that the temperature difference between the coil temperature and the outdoor ambient temperature is within the required range. The current speed Vt of the outdoor fan can meet the heat exchange requirements of the air conditioner. Controlling the outdoor fan to continue running at the current speed Vt can ensure the normal operation of the air conditioner.

[0087] The transition time of an outdoor fan from its current speed Vt to its target speed Vs is usually quite short. If the difference between the target speed Vs and the current speed Vt is too large, the speed change rate of the outdoor fan will be large, which can easily reduce the safety, reliability and stability of the outdoor fan's operation.

[0088] Based on this, the target speed Vs of the outdoor fan is limited in this application to prevent the difference between the current speed Vt and the target speed Vs from being too large, which would cause refrigerant pressure fluctuations.

[0089] like Figure 4 As shown, the controller is configured to: when the first difference T1 is greater than or equal to the first set value S1, calculate the difference between the current speed Vt and the target speed Vs as the second difference T2; if the second difference T2 is less than or equal to the second threshold, control the outdoor fan to operate at the target speed Vs as the actual speed; if the second difference T2 is greater than the second threshold, control the outdoor fan to finally operate at the second speed V2 as the target speed Vs; wherein, the difference between the current speed Vt and the second speed V2 is the second threshold.

[0090] When determining the target speed Vs of the outdoor fan based on the coil temperature, if the second difference T2 is greater than the second threshold, the outdoor fan is controlled to operate with the second speed V2 as the target speed Vs. This is to prevent the target speed Vs from being too large compared to the current speed Vt, which would cause the outdoor fan to change too much and reduce the safety of the outdoor fan's operation. In addition, large changes in the outdoor fan speed can easily lead to large changes in the heat exchange rate of the outdoor heat exchanger, which can easily cause refrigerant pressure fluctuations and lead to unstable operation of the air conditioner.

[0091] In some embodiments of this application, in order to prevent large changes in the speed of the outdoor fan, the amount of change in the speed of the outdoor fan is limited to prevent the rate of change of the outdoor fan speed from being too large, which would lead to large changes in the heat dissipation of the outdoor heat exchanger, thereby causing fluctuations in refrigerant pressure and resulting in unstable operation of the air conditioner.

[0092] Specifically, the controller is configured to: control the outdoor fan speed to decrease by a multiple of a first threshold; when the first difference T1 is greater than or equal to the first set value S1, control the outdoor fan speed to decrease by at most a third threshold; when the first difference T1 is less than the second set value S2, control the outdoor fan speed to decrease by at most the first threshold.

[0093] The trend of coil temperature change is generally divided into three types: rising, falling, and stable. Based on the trend of coil temperature change, it can be inferred that the heat exchange capacity of the outdoor heat exchanger is also divided into three types: rising, falling, and stable. The trend of heat exchange capacity change of the outdoor heat exchanger is the same as the trend of coil temperature change and is affected by the trend of coil temperature change.

[0094] When the coil temperature is constant, different trends in coil temperature will result in different changes in the heat exchange capacity of the outdoor heat exchanger, and consequently, different target speeds (Vs) of the outdoor fan. Therefore, by obtaining the trend of coil temperature changes, the trend of heat exchange capacity changes in the outdoor heat exchanger can be predicted. Determining the operating speed of the outdoor fan based on this trend can improve the heat dissipation effect of the outdoor fan on the outdoor heat exchanger.

[0095] Specifically, the controller is configured to periodically acquire the detection value of the coil temperature sensor, determine the trend of coil temperature change based on the detection value of the coil temperature sensor, and determine the operating speed of the outdoor fan based on the trend of coil temperature change and the detection value of the coil temperature sensor when the first difference T1 is greater than or equal to the first set value S1.

[0096] It should be noted that even if the coil temperature sensor readings are the same, the target speed Vs of the outdoor fan will be different when the coil temperature shows different trends.

[0097] like Figure 5As shown, the controller is configured to: acquire the current detection value P1 of the coil temperature sensor and the next detection value P2 of the coil temperature sensor; calculate the absolute value of the difference between the two as a third difference T3; if the current detection value P1 of the coil temperature sensor is less than the next detection value P2 and the third difference T3 is greater than or equal to the first reference value C1, then the change in coil temperature is determined to be an upward trend; if the current detection value P1 of the coil temperature sensor is greater than the next detection value P2 and the third difference T3 is greater than or equal to the first reference value C1, then the change in coil temperature is determined to be a downward trend; if the absolute value of the difference between the current detection value P1 and the next detection value P2 of the coil temperature sensor is less than the first reference value C1, then the change in coil temperature is determined to be a stable trend.

[0098] Theoretically, given the same first difference T1, the target outdoor fan speed Vs determined when the coil temperature is rising will be different from the target outdoor fan speed Vs determined when it is falling. However, in practical applications, there are also cases where the target outdoor fan speed Vs determined when the coil temperature is rising is the same as the target outdoor fan speed Vs determined when it is falling.

[0099] For ease of description, the target speed Vs of the outdoor fan determined when the coil temperature is changing upward is called the rising target speed Vss, and the target speed Vs of the outdoor fan determined when the coil temperature is changing downward is called the falling target speed Vsj.

[0100] Theoretically, given the same first difference T1, the target speed Vss for rising coils at the same coil temperature is less than the target speed Vsj for falling coils. However, in practical applications, there are also cases where the target speed Vss for rising coils at the same coil temperature is the same as the target speed Vsj for falling coils.

[0101] It should be noted that when the coil temperature shows a stable trend, it indicates that the heat exchange capacity of the outdoor heat exchanger is also stable, and the refrigerant pressure is also stable. Therefore, the current speed Vt of the outdoor fan meets the operating requirements of the air conditioner.

[0102] The controller is configured to control the outdoor fan to continue operating at the current speed Vt if the coil temperature shows a stable trend.

[0103] When the air conditioner starts running, the coil temperature may be temporarily abnormal. When the coil temperature is abnormal, the first difference T1 is prone to large errors, making the target speed Vs of the outdoor fan inaccurate. Therefore, in this application, the target speed Vs of the outdoor fan is limited by an upper limit Vmax and a lower limit Vmin to ensure the safety, reliability and stability of the outdoor fan, thereby ensuring the safety, reliability and stability of the air conditioner.

[0104] Specifically, such as Figure 6 As shown, the controller is configured to: determine the upper limit Vmax and lower limit Vmin of the outdoor fan speed based on the detection value of the outdoor temperature sensor; when the target speed Vs of the outdoor fan is less than the lower limit Vmin, control the outdoor fan to operate at the lower limit Vmin speed; when the target speed Vs of the outdoor fan is greater than the upper limit Vmax, control the outdoor fan to operate at the upper limit Vmax speed; when the target speed Vs of the outdoor fan is greater than or equal to the lower limit Vmin and less than or equal to the upper limit Vmax, control the outdoor fan to operate at the target speed Vs.

[0105] It should be noted that in this application, a pre-set correspondence between outdoor ambient temperature and outdoor fan speed is established. The outdoor ambient temperature can be determined based on the detection value of the outdoor temperature sensor, thereby determining the outdoor fan speed corresponding to the outdoor ambient temperature.

[0106] The upper limit Vmax and lower limit Vmin of the outdoor fan speed are determined based on the outdoor ambient temperature. The target speed Vs of the outdoor fan is limited by the upper limit Vmax and lower limit Vmin to avoid instability and insecurity of the air conditioner operation caused by abnormal coil temperature.

[0107] like Figure 7 As shown, the control process of the outdoor fan in the outdoor unit of the air conditioner is as follows: determine the initial target speed Vs1 of the outdoor fan, then correct the initial target speed Vs1 of the outdoor fan to obtain the intermediate target speed Vs2 of the outdoor fan, and finally use the upper limit value Vmax and the lower limit value Vmin of the outdoor fan speed to correct the intermediate target speed Vs2 of the outdoor fan to obtain the final target speed Vs3 of the outdoor fan.

[0108] It should be noted that when the air conditioner is in cooling mode, the outdoor fan first starts running at an initial speed V0 to allow air to circulate around the outdoor heat exchanger, thereby making the detected coil temperature more accurate.

[0109] In this application, the initial speed V0 of the outdoor fan is determined based on the outdoor ambient temperature. After the outdoor fan has been running at the initial speed V0 for a preset time, the detection value of the coil temperature sensor is obtained to ensure the accuracy of the detection value of the coil temperature sensor.

[0110] The controller is configured to: determine the initial speed of the outdoor fan based on the outdoor ambient temperature detected by the outdoor temperature sensor when the outdoor unit of the air conditioner starts to run in cooling mode; and after controlling the outdoor fan to run at the initial speed for a preset time, obtain the detection value of the coil temperature sensor.

[0111] It should be noted that the higher the outdoor ambient temperature, the greater the initial speed V0 of the outdoor fan; the lower the outdoor ambient temperature, the smaller the initial speed V0 of the outdoor fan.

[0112] It should also be noted that when the air conditioner starts cooling, the outdoor fan speed is the initial speed V0. After a logical judgment is made on the outdoor fan speed, the actual speed of the outdoor fan may change. During the cooling operation of the air conditioner, the control logic of the outdoor fan speed is judged every once in a while to ensure the control effect of the outdoor fan speed.

[0113] In this application, the variables determined based on the outdoor ambient temperature parameter include at least three: the initial speed V0 of the outdoor fan, the upper limit value Vmax of the outdoor fan speed, and the lower limit value Vmin of the outdoor fan speed. Among these three variables determined by the same outdoor ambient temperature, the initial speed V0 of the outdoor fan is greater than the upper limit value Vmax of the outdoor fan speed, the initial speed V0 of the outdoor fan is less than or equal to the lower limit value Vmin of the outdoor fan speed, and the upper limit value Vmax of the outdoor fan speed is less than or equal to the lower limit value Vmin of the outdoor fan speed.

[0114] During the refrigeration operation of the outdoor unit of an air conditioner, the operation of the outdoor fan can be roughly divided into two processes: preliminary operation and actual operation. During the preliminary operation, the outdoor fan operates at an initial speed V0; during the actual operation, the outdoor fan operates at the final target speed Vs3.

[0115] It should be noted that in actual operation, the controller uses different control logic to adjust and control the outdoor fan's final target speed Vs3 based on the outdoor ambient temperature, coil temperature, and the current speed Vt of the outdoor fan. The final target speed Vs3 is not a fixed value.

[0116] It should also be noted that the process of the controller adjusting and controlling the speed of the outdoor fan involves multiple controls of the outdoor fan, and these multiple controls are performed in chronological order.

[0117] The following example demonstrates the controller's control principle by showing how the controller controls the outdoor fan's speed twice.

[0118] like Figure 8 As shown, the controller is configured to: acquire the detection value of the outdoor temperature sensor when the outdoor unit of the air conditioner is initially cooling, and determine the initial speed V0 of the outdoor fan, the upper limit value Vmax of the outdoor fan speed, and the lower limit value Vmin of the outdoor fan speed based on the detection value of the outdoor temperature sensor.

[0119] The controller is further configured to: after the outdoor fan has been running at an initial speed V0 for a preset time, acquire the detection value of the coil temperature sensor, calculate the difference between the detection value of the coil temperature sensor and the detection value of the outdoor temperature sensor as the first difference T1, and acquire the trend of coil temperature change.

[0120] The controller is further configured to: determine the initial target speed Vs1 of the outdoor fan based on the relationship between the first difference T1 and the first set value S1 and the second set value S2; determine the intermediate target speed Vs2 of the outdoor fan based on the relationship between the initial target speed Vs1 and the initial speed V0 of the outdoor fan; and determine the final target speed Vs3 of the outdoor fan based on the relationship between the intermediate target speed Vs2 and the upper limit value Vmax and the lower limit value Vmin of the outdoor fan speed.

[0121] When determining the initial target speed Vs1 of the outdoor fan, the controller is configured as follows: if the first difference T1 is greater than or equal to the first set value S1, the initial target speed Vs1 of the outdoor fan is determined based on the detection value of the coil temperature sensor and the trend of coil temperature change; if the first difference T1 is less than the second set value S2, the first speed V1 is taken as the initial target speed Vs1 of the outdoor fan, and the difference between the first speed V1 and the initial speed V0 is the first threshold; if the first difference T1 is less than the first set value S1 and greater than or equal to the second set value S2, the initial speed V0 is taken as the initial target speed Vs1 of the outdoor fan.

[0122] When determining the intermediate target speed Vs2, the controller is further configured as follows: when the first difference T1 is greater than or equal to the first set value S1, if the initial speed V0 is greater than the initial target speed Vs1 and the difference between the two is greater than a second threshold, then the outdoor fan is controlled to use the second speed V2 as the intermediate target speed Vs2; wherein, the difference between the initial speed V0 and the second speed V2 is the second threshold; if the difference between the two is less than the second threshold, then the outdoor fan is controlled to use the initial target speed Vs1 as the intermediate target speed Vs2. When the first difference T1 is less than the second set value S2, the outdoor fan is controlled to use the first speed V1 as the intermediate target speed Vs2.

[0123] When determining the final target speed Vs3 of the outdoor fan, the controller is configured as follows: when the initial target speed Vs1 of the outdoor fan is less than the lower limit Vmin, the outdoor fan is controlled to use the lower limit Vmin as the final target speed Vs3; when the initial target speed Vs1 of the outdoor fan is greater than the upper limit Vmax, the outdoor fan is controlled to use the upper limit Vmax as the final target speed Vs3; when the initial target speed Vs1 of the outdoor fan is greater than or equal to the lower limit Vmin and less than or equal to the upper limit Vmax, the outdoor fan is controlled to use the initial target speed Vs1 as the final target speed Vs3.

[0124] The controller is further configured to control the outdoor fan to operate at the final target speed Vs3. At this point, the controller has completed its first control of the outdoor fan speed.

[0125] like Figure 9 As shown, the controller is further configured to: acquire the detection value of the coil temperature sensor again, calculate the difference between the detection value of the coil temperature sensor and the detection value of the outdoor temperature sensor as the first difference T1, and acquire the trend of coil temperature change.

[0126] The controller is further configured to: determine the initial target speed Vs1 of the outdoor fan based on the relationship between the first difference T1 and the first set value S1 and the second set value S2; determine the intermediate target speed Vs2 of the outdoor fan based on the relationship between the initial target speed Vs1 of the outdoor fan and the current speed Vt of the outdoor fan; and determine the final target speed Vs3 of the outdoor fan based on the relationship between the intermediate target speed Vs2 of the outdoor fan and the upper limit value Vmax and the lower limit value Vmin of the outdoor fan speed.

[0127] When determining the initial target speed Vs1 of the outdoor fan, the controller is configured as follows: if the first difference T1 is greater than or equal to the first set value S1, the initial target speed Vs1 of the outdoor fan is determined based on the detection value of the coil temperature sensor and the trend of coil temperature change; if the first difference T1 is less than the second set value S2, the first speed V1 is taken as the initial target speed Vs1 of the outdoor fan, and the difference between the first speed V1 and the current speed Vt is the first threshold; if the first difference T1 is less than the first set value S1 and greater than or equal to the second set value S2, the current speed Vt is taken as the initial target speed Vs1 of the outdoor fan.

[0128] When determining the intermediate target speed Vs2, the controller is further configured as follows: when the first difference T1 is greater than or equal to the first set value S1, if the current speed Vt is greater than the initial target speed Vs1 and the difference between the two is greater than a second threshold, then the outdoor fan is controlled to use the second speed V2 as the intermediate target speed Vs2; wherein, the difference between the current speed Vt and the second speed V2 is the second threshold; if the difference between the two is less than the second threshold, then the outdoor fan is controlled to use the initial target speed Vs1 as the intermediate target speed Vs2. When the first difference T1 is less than the second set value S2, the outdoor fan is controlled to use the first speed V1 as the intermediate target speed Vs2.

[0129] When determining the final target speed Vs3 of the outdoor fan, the controller is configured as follows: when the initial target speed Vs1 of the outdoor fan is less than the lower limit Vmin, the outdoor fan is controlled to use the lower limit Vmin as the final target speed Vs3; when the initial target speed Vs1 of the outdoor fan is greater than the upper limit Vmax, the outdoor fan is controlled to use the upper limit Vmax as the final target speed Vs3; when the initial target speed Vs1 of the outdoor fan is greater than or equal to the lower limit Vmin and less than or equal to the upper limit Vmax, the outdoor fan is controlled to use the initial target speed Vs1 as the final target speed Vs3.

[0130] The controller is further configured to control the outdoor fan to operate at the final target speed Vs3. At this point, the controller has completed the second control of the outdoor fan speed.

[0131] It should be noted that the current speed Vt of the outdoor fan in the second control is the final target speed Vs3 of the outdoor fan in the first control.

[0132] In practical applications, controllers typically control the outdoor fan's speed by adjusting its speed settings. Outdoor fans usually have multiple speed settings, each corresponding to a specific rotational speed. The controller controls the outdoor fan's speed by adjusting its speed settings; this is common knowledge in the field and will not be elaborated further.

[0133] In this application, the corresponding temperature levels for the same coil are not entirely the same when the coil temperature changes in different trends.

[0134] In this embodiment, the control principle of an outdoor fan with 16 speed settings is described in detail.

[0135] The outdoor fan has 16 speed settings, from D1 to D16. When the outdoor sensor detects a value less than the first temperature value T1, the initial speed setting of the outdoor fan is D5; when the outdoor sensor detects a value greater than or equal to the first temperature value T1 and less than the second temperature value T2, the initial speed setting of the outdoor fan is D10; when the outdoor sensor detects a value greater than or equal to the second temperature value T2 and less than the third temperature value T3, the initial speed setting of the outdoor fan is D15; and when the outdoor sensor detects a value greater than or equal to the third temperature value T3, the initial speed setting of the outdoor fan is D16.

[0136] like Figure 10 As shown, the upper and lower speed limits of the outdoor fan are determined based on the outdoor ambient temperature, which will not be elaborated here.

[0137] In this embodiment, if the difference between the coil temperature at the next moment and the coil temperature at the previous moment is ≥1℃, the coil temperature change shows an upward trend; if the difference between the coil temperature at the next moment and the coil temperature at the previous moment is ≤-1℃, the coil temperature change shows a downward trend; otherwise, the coil temperature change shows a stable trend.

[0138] When the coil temperature shows an upward trend, the relationship between the coil temperature and the outdoor fan speed is shown in Table 1. When the coil temperature shows a downward trend, the relationship between the coil temperature and the outdoor fan speed is shown in Table 2.

[0139] Appendix 1: Correspondence between external ambient temperature and gear position during coil temperature rise

[0140]

[0141] Appendix 2: Correspondence between Ambient Temperature and Equipment Level during Coil Temperature Decrease

[0142]

[0143] like Figure 11 As shown, the outdoor temperature sensor detects the value, and the initial speed of the outdoor fan, as well as the upper and lower limits of the outdoor fan speed, are determined based on the outdoor temperature sensor detects the value.

[0144] When the air conditioner starts cooling, after the outdoor fan runs at the initial speed for 3 minutes, the detection value of the coil temperature sensor is obtained. The difference between the detection value of the coil temperature sensor and the detection value of the outdoor temperature sensor is calculated as the first difference T1, and the trend of coil temperature change is obtained.

[0145] If the first difference T1 is greater than or equal to the first set value S1, when the coil temperature changes with an upward trend, the initial target speed of the outdoor fan is determined according to the data in Table 1; when the coil temperature changes with a downward trend, the initial target speed of the outdoor fan is determined according to the data in Table 2; when the coil temperature changes with a stable trend, the initial speed of the outdoor fan is used as the initial target speed. It should be noted that when the initial target speed decreases compared to the initial speed, if the decrease exceeds two speeds, the outdoor fan is controlled to use the speed after the initial speed is reduced by two speeds as the intermediate target speed; if the decrease does not exceed two speeds, the outdoor fan is controlled to use the initial target speed as the intermediate target speed.

[0146] If the first difference T1 is less than the second set value S2, then the outdoor fan is controlled to use the gear that is one gear lower than the current gear as the intermediate target gear.

[0147] If the first difference T1 is less than the first set value S1 and greater than or equal to the second set value S2, then control the outdoor fan to use the current gear as the intermediate target gear.

[0148] When the target speed of the outdoor fan is lower than the lower limit, the outdoor fan is controlled to operate at the lower limit as the final speed; when the target speed of the outdoor fan is higher than the upper limit, the outdoor fan is controlled to operate at the upper limit as the final speed; when the target speed of the outdoor fan is greater than or equal to the lower limit and less than or equal to the upper limit, the outdoor fan is controlled to operate at the target speed as the final speed.

[0149] During the cooling operation of the air conditioner, the detection values ​​of the coil temperature sensor and the outdoor temperature sensor are re-acquired at regular intervals to re-determine the speed of the outdoor fan.

[0150] When the outdoor unit of the air conditioner is running in cooling mode, it can achieve stable control of the outdoor fan speed under different outdoor ambient temperature conditions, thereby ensuring that the refrigerant pressure in the air conditioning system meets the safe operating conditions and does not fluctuate. At the same time, it can ensure that the refrigerant temperature in the outdoor heat exchanger has an ideal temperature difference with the outdoor ambient temperature, thus ensuring the heat dissipation effect.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0152] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. An air conditioner outdoor unit characterized by comprising: The application relates to an air conditioner comprising: a condenser for heat exchange with outdoor air; a compressor for compressing low-pressure refrigerant gas into high-pressure refrigerant gas and driving refrigerant to flow in a refrigerant circulation loop formed by the condenser and the evaporator; an outdoor fan for driving air to contact the condenser; a coil temperature sensor for detecting the coil temperature of the condenser; an outdoor temperature sensor for detecting the outdoor ambient temperature; a controller connected with the outdoor fan, the coil temperature sensor and the outdoor temperature sensor respectively; the controller is configured to: obtain the outdoor ambient temperature detected by the outdoor temperature sensor and the coil temperature detected by the coil temperature sensor, and calculate the difference between the coil temperature and the outdoor ambient temperature as a first difference; if the first difference is greater than or equal to a first set value, obtain the target rotating speed of the outdoor fan according to the preset corresponding relationship between the coil temperature and the rotating speed of the outdoor fan and the change trend of the coil temperature; if the first difference is less than a second set value, take the first rotating speed as the target rotating speed of the outdoor fan; wherein the first rotating speed is less than the current rotating speed of the outdoor fan; the absolute value of the difference between the current rotating speed of the outdoor fan and the first rotating speed is a first threshold value; if the first difference is less than the first set value and greater than or equal to the second set value, take the current rotating speed of the outdoor fan as the target rotating speed of the outdoor fan; when the first difference is greater than or equal to the first set value, if the coil temperature changes in a stable trend, control the outdoor fan to continue running at the current rotating speed; if not, control the outdoor fan to run at the target rotating speed.

2. The air conditioner outdoor unit according to claim 1, characterized by The controller is further configured to determine the upper limit value and the lower limit value of the rotating speed of the outdoor fan according to the preset corresponding relationship between the outdoor ambient temperature and the rotating speed of the outdoor fan; if the target rotating speed of the outdoor fan is less than the lower limit value, control the outdoor fan to run at the lower limit value as the actual rotating speed; if the target rotating speed of the outdoor fan is greater than the upper limit value, control the outdoor fan to run at the upper limit value as the actual rotating speed; if the target rotating speed of the outdoor fan is greater than or equal to the lower limit value and less than or equal to the upper limit value, control the outdoor fan to run at the target rotating speed as the actual rotating speed.

3. The air conditioner outdoor unit according to claim 1 or 2, characterized by The controller is further configured to, when the first difference is greater than or equal to the first set value, if the difference between the current rotating speed of the outdoor fan and the target rotating speed is less than or equal to a second threshold value, control the rotating speed of the outdoor fan to run at the target rotating speed as the actual rotating speed; if the difference between the current rotating speed of the outdoor fan and the target rotating speed is greater than the second threshold value, control the outdoor fan to finally run at the second rotating speed as the actual rotating speed; wherein the difference between the current rotating speed of the outdoor fan and the second rotating speed is the second threshold value.

4. The air conditioner outdoor unit according to claim 1, characterized by The controller is further configured to, when the first difference is greater than or equal to the first set value, if the target rotating speed is less than the current rotating speed of the outdoor fan, control the rotating speed of the outdoor fan to change at most by a third threshold value.

5. The air conditioner outdoor unit according to claim 1, characterized by In the case that the first difference is the same, the target rotating speed determined when the coil temperature changes in an upward trend is smaller than the target rotating speed determined when the coil temperature changes in a downward trend.

6. The air conditioner outdoor unit according to claim 1, characterized by The controller is configured to determine an initial rotating speed of the outdoor fan according to the outdoor environment temperature detected by the outdoor temperature sensor when the outdoor unit of the air conditioner starts the refrigeration operation. After the outdoor fan is controlled to operate at the initial rotating speed for a preset time, the detection value of the coil temperature sensor is obtained.

7. The air conditioner outdoor unit according to claim 6, characterized by The initial rotating speed of the outdoor fan is greater than or equal to the upper limit of the rotating speed of the outdoor fan, and the initial rotating speed of the outdoor fan is less than or equal to the lower limit of the rotating speed of the outdoor fan.

8. An air conditioner outdoor unit characterized by comprising: Comprise: a condenser for heat exchange with outdoor air; a compressor which forms a refrigerant circulation loop together with the condenser and the evaporator, the compressor being used for compressing low-pressure refrigerant gas into high-pressure refrigerant gas and driving the refrigerant to flow in the refrigerant circulation loop; an outdoor fan for driving air to contact the condenser, the outdoor fan being provided with multiple gears, each gear being provided with a corresponding rotating speed; a coil temperature sensor for detecting the coil temperature; an outdoor temperature sensor for detecting the outdoor environment temperature; a controller connected with the outdoor fan, the coil temperature sensor and the outdoor temperature sensor respectively; the controller is configured to: obtain the detection value of the outdoor temperature sensor and the detection value of the coil temperature sensor, and calculate the difference between the detection value of the coil temperature sensor and the detection value of the outdoor temperature sensor as a first difference; determine the initial target gear of the outdoor fan according to the relationship between the first difference and a set value; correct the initial target gear of the outdoor fan to obtain the final target gear of the outdoor fan, and control the outdoor fan to continue operating at the final target gear.

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