Air conditioner and control method thereof

Abstract

The application discloses an air conditioner and a control method thereof. The first pressure sensor is arranged at the exhaust port of the compressor, and the second pressure sensor is arranged at the suction port of the compressor. When the temperature is high, the exhaust pressure value detected by the first pressure sensor and the suction pressure value detected by the second pressure sensor are obtained. The exhaust pressure value is compared with a plurality of pressure ranges, and the operating frequency of the compressor is adjusted according to the comparison result. The pressure ratio of the exhaust pressure value and the suction pressure value is calculated, the pressure ratio is compared with a plurality of ratio thresholds, and the opening of the electronic expansion valve is adjusted according to the comparison result. By detecting the real-time system pressure, the unit can adjust the relevant parameters in time according to the real-time pressure parameter and the corresponding correction temperature, effectively solve the problem of the coil temperature hysteresis reflection, avoid the lagging adjustment affecting the sustainable stable operation of the system, and reduce the unnecessary protection shutdown.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to an air conditioner and its control method. Background Technology

[0002] In harsh environments such as high temperatures, the reliable operation of air conditioners is particularly important. To ensure reliability, system pressure is a critical parameter that requires close monitoring and control. Currently, air conditioners are equipped with pressure detectors, but the unit's operation is still controlled by pipe temperature (such as exhaust temperature, superheat, etc.) to determine and control compressor operating frequency, fan speed, valve opening, etc., thereby adjusting system parameters. The unit only initiates shutdown protection when the system pressure reaches the pressure switch's protection value. However, these pressure detection devices cannot participate in the system adjustment control during unit operation. While the conventional method of monitoring and controlling unit operation through pipe temperature is available, it suffers from a certain lag, failing to reflect real-time system pressure conditions. This results in unit control lag, especially in harsh environments, hindering the unit's timely adjustment of relevant parameters and leading to abnormal or delayed shutdowns, affecting the unit's lifespan and comfort. Summary of the Invention

[0003] The purpose of this invention is to provide an air conditioner and its control method. In high-temperature and harsh environments, by detecting the real-time system pressure, the unit can adjust relevant parameters in a timely manner according to the real-time pressure parameters and their corresponding correction temperatures. This effectively solves the problem of lag in coil temperature response, avoids lag in adjustment affecting the sustainable and stable operation of the system, and reduces unnecessary protection shutdowns.

[0004] To achieve the above objectives, embodiments of the present invention provide an air conditioner, comprising:

[0005] The refrigerant circuit circulates sequentially through the compressor, condenser, electronic expansion valve, and evaporator in the refrigeration cycle. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger. The compressor is equipped with an intake port and an exhaust port.

[0006] A first pressure sensor is located at the exhaust port of the compressor and is used to detect the exhaust pressure value at the exhaust port.

[0007] The second pressure sensor is located at the air intake of the compressor and is used to detect the air intake pressure value at the air intake.

[0008] Ambient temperature sensor, used to detect ambient temperature values;

[0009] A controller, which controls at least the compressor and the electronic expansion valve, is configured to:

[0010] When the ambient temperature value detected by the ambient temperature sensor is greater than or equal to the preset ambient temperature threshold, the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor are obtained.

[0011] The discharge pressure value is compared with several pre-stored pressure ranges to adjust the operating frequency of the compressor based on the comparison results.

[0012] Calculate the pressure ratio between the exhaust pressure value and the intake pressure value;

[0013] The pressure ratio is compared with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results.

[0014] As an improvement to the above solution, the pressure range includes a frequency-blocking pressure range, a frequency-reducing pressure range, and a shutdown pressure range; therefore, the controller is further configured as follows:

[0015] When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency restriction pressure range, the compressor is controlled to maintain the current operating frequency.

[0016] When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency reduction pressure range, the operating frequency of the compressor is reduced.

[0017] When the exhaust pressure values ​​obtained within a certain period of time are all within the shutdown pressure range, the compressor is controlled to shut down.

[0018] As an improvement to the above scheme, the ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold, and the controller is further configured to:

[0019] When the pressure ratio is greater than the first ratio threshold, the opening of the electronic expansion valve is increased;

[0020] When the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold, the electronic expansion valve is controlled to remain at the current opening degree.

[0021] When the pressure ratio is less than the second ratio threshold, the opening of the electronic expansion valve is reduced.

[0022] As an improvement to the above solution, the controller is further configured to:

[0023] The corresponding high-pressure correction temperature is obtained based on the exhaust pressure value;

[0024] The difference between the compressor's exhaust temperature and the high-pressure correction temperature is calculated as the target superheat, and the actual superheat is also calculated.

[0025] The target superheat is compared with the actual superheat, and the opening of the electronic expansion valve is adjusted according to the comparison result.

[0026] As an improvement to the above solution, the controller is further configured to:

[0027] Based on the exhaust pressure value, a target pressure range is obtained from a preset number of pressure ranges; wherein, each pressure range corresponds to a high-pressure correction temperature;

[0028] The corresponding high-pressure correction temperature is obtained based on the target pressure range.

[0029] To achieve the above objectives, this invention also provides an air conditioner control method. The air conditioner includes a first pressure sensor disposed at the compressor exhaust port and a second pressure sensor disposed at the compressor intake port. The first sensor is used to detect the exhaust pressure value at the exhaust port, and the second sensor is used to detect the intake pressure value at the intake port. Therefore, the air conditioner control method includes:

[0030] When the ambient temperature value is greater than or equal to the preset ambient temperature threshold, the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor are obtained.

[0031] The discharge pressure value is compared with several pre-stored pressure ranges to adjust the operating frequency of the compressor based on the comparison results.

[0032] Calculate the pressure ratio between the exhaust pressure value and the intake pressure value;

[0033] The pressure ratio is compared with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve in the air conditioner based on the comparison results.

[0034] As an improvement to the above solution, the pressure range includes a frequency-restricted pressure range, a frequency-reduced pressure range, and a shutdown pressure range; therefore, adjusting the compressor's operating frequency based on the comparison results includes:

[0035] When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency restriction pressure range, the compressor is controlled to maintain the current operating frequency.

[0036] When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency reduction pressure range, the operating frequency of the compressor is reduced.

[0037] When the exhaust pressure values ​​obtained within a certain period of time are all within the shutdown pressure range, the compressor is controlled to shut down.

[0038] As an improvement to the above scheme, the ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold; then, adjusting the opening of the electronic expansion valve in the air conditioner according to the comparison result includes:

[0039] When the pressure ratio is greater than the first ratio threshold, the opening of the electronic expansion valve is increased;

[0040] When the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold, the electronic expansion valve is controlled to remain at the current opening degree.

[0041] When the pressure ratio is less than the second ratio threshold, the opening of the electronic expansion valve is reduced.

[0042] As an improvement to the above solution, the method further includes:

[0043] The corresponding high-pressure correction temperature is obtained based on the exhaust pressure value;

[0044] The difference between the compressor's exhaust temperature and the high-pressure correction temperature is calculated as the target superheat, and the actual superheat is also calculated.

[0045] The target superheat is compared with the actual superheat, and the opening of the electronic expansion valve is adjusted according to the comparison result.

[0046] As an improvement to the above solution, obtaining the corresponding high-pressure correction temperature based on the exhaust pressure value includes:

[0047] Based on the exhaust pressure value, a target pressure range is obtained from a preset number of pressure ranges; wherein, each pressure range corresponds to a high-pressure correction temperature;

[0048] The corresponding high-pressure correction temperature is obtained based on the target pressure range.

[0049] Compared to existing technologies, the air conditioner and its control method disclosed in this invention, by setting a first pressure sensor at the compressor's exhaust port and a second pressure sensor at the compressor's intake port, acquires the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor in a high-temperature environment. The exhaust pressure value is compared with several pressure ranges as the system pressure to adjust the compressor's operating frequency based on the comparison results. Furthermore, the pressure ratio between the exhaust pressure value and the intake pressure value is calculated and compared with several ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results. By detecting the real-time system pressure, the unit can promptly adjust relevant parameters based on the real-time pressure parameters and their corresponding correction temperatures, effectively solving the problem of lag in coil temperature response, avoiding the impact of lag adjustment on the system's sustainable and stable operation, and reducing unnecessary protective shutdowns. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of an air conditioner provided in an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the refrigerant flow direction when the air conditioner is operating in cooling mode, provided in an embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the refrigerant flow direction when the air conditioner is operating in heating mode, according to an embodiment of the present invention.

[0053] Figure 4 This is a schematic diagram of the internal structure of the indoor unit of the air conditioner provided in an embodiment of the present invention;

[0054] Figure 5 This is a first working flowchart of the controller in an air conditioner provided in an embodiment of the present invention;

[0055] Figure 6 This is a second working flowchart of the controller in an air conditioner provided in an embodiment of the present invention;

[0056] Figure 7 This is a third working flowchart of the controller in an air conditioner provided in an embodiment of the present invention;

[0057] Figure 8 This is the fourth workflow diagram of the controller in the air conditioner provided in the embodiment of the present invention;

[0058] Figure 9 This is the fifth workflow diagram of the controller in the air conditioner provided in the embodiment of the present invention;

[0059] Figure 10 This is a flowchart of an indoor fan speed control method for an air conditioner provided in an embodiment of the present invention.

[0060] Among them, 100 is the indoor unit; 200 is the outdoor unit; 11 is the compressor; 12 is the four-way valve; 13 is the outdoor heat exchanger; 14 is the expansion valve; 15 is the indoor heat exchanger; 16 is the indoor fan; 17 is the outdoor fan; 201 is the first pressure sensor; 202 is the second pressure sensor; 111 is the horizontal air guide plate; 112 is the vertical air guide plate; 10A is the air outlet; 10B is the air intake; 101 is the housing; 1031 is the coil; and 1032 is the heat sink. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0063] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0064] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0065] See Figure 1 , Figure 1This is a schematic diagram of the structure of an air conditioner according to an embodiment of the present invention. The air conditioner according to the embodiment of the present invention includes an indoor unit 100 and an outdoor unit 200. The indoor unit 100 is used to regulate the temperature and humidity of the indoor air, and the outdoor unit 200 is connected to the indoor unit 100 through a connecting pipe. The outdoor unit 200 is installed outdoors, and the indoor unit 100 is installed indoors.

[0066] See Figure 2 The air conditioner includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an expansion valve 14, an indoor heat exchanger 15, an indoor fan 16, an outdoor fan 17, a first pressure sensor 201, and a second pressure sensor 202. The indoor heat exchanger 15 and the indoor fan 16 are mounted on the indoor unit 100, while the compressor 11, the four-way valve 12, the outdoor heat exchanger 13, the expansion valve 14, the outdoor fan 17, the first pressure sensor 201, and the second pressure sensor 202 are mounted on the outdoor unit. It is worth noting that the expansion valve 14 can also be mounted on the indoor unit 100. Figure 2 The illustration is for illustrative purposes only. The first pressure sensor 201 is located at the exhaust port of the compressor 11 to detect the exhaust pressure value. The second pressure sensor 202 is located at the intake port of the compressor 11 to detect the intake pressure value. An ambient temperature sensor is installed on the outdoor unit to detect the ambient temperature.

[0067] The air conditioner described in this embodiment of the invention includes cooling and heating modes. The refrigerant flows differently during cooling and heating. In cooling mode, the refrigerant first flows through the outdoor unit's heat exchanger, where the outdoor unit acts as the condenser and the indoor unit as the evaporator. In heating mode, the refrigerant first flows through the indoor unit's heat exchanger, where the indoor unit acts as the condenser and the outdoor unit as the evaporator. The air conditioner uses a four-way valve to change the refrigerant flow direction during these different modes. Without the four-way valve, the air conditioner could only perform either cooling or heating, and could not switch between cooling and heating modes.

[0068] See Figure 2 When the air conditioner is cooling, the refrigerant first passes through the compressor 11 to become a high-pressure gas, and then passes through the outdoor heat exchanger 13 (condenser) to condense and release heat to become a high-pressure liquid. The high-pressure liquid passes through the expansion valve 14 and becomes a low-temperature, low-pressure liquid. It then passes through the indoor heat exchanger 15 (evaporator) to evaporate and absorb heat to become a low-temperature, low-pressure gas, and finally returns to the compressor 11.

[0069] See Figure 3When the air conditioner is heating, the refrigerant first passes through the compressor 11 to become a high-pressure gas, and then passes through the indoor heat exchanger 15 (condenser) to condense and release heat to become a high-pressure liquid. The high-pressure liquid passes through the expansion valve and becomes a low-temperature, low-pressure liquid. The low-temperature, low-pressure liquid passes through the outdoor heat exchanger 13 (evaporator) to evaporate and absorb heat to become a low-temperature, low-pressure gas, and finally returns to the compressor 11.

[0070] See Figure 4 , Figure 4 This is a schematic diagram of the internal structure of the indoor unit 100 provided in an embodiment of the present invention. The indoor unit 100 includes a housing 101, an indoor fan 16, and an indoor heat exchanger 15.

[0071] The housing 101 is a box-shaped structure extending slenderly along its length (hereinafter also referred to as the left-right direction) and having multiple openings. Several air intakes 10B are provided on the top surface of the housing 101. Driven by the indoor fan 16, indoor air near the air intakes 10B is drawn into the interior of the housing 101 through these air intakes 10B. The indoor air drawn in from the air intakes 10B is then transported to the indoor fan 16 via an indoor heat exchanger 15. An air outlet 10A is formed on the bottom surface of the housing 101, and the air outlet 10A is connected to the interior of the housing 101 via a continuous vortex flow path from the indoor fan 16. After heat exchange by the indoor heat exchanger 15, the indoor air drawn in from the air intakes 10B is blown out into the room through the vortex flow path from the air outlet 10A.

[0072] The indoor heat exchanger 15 consists of multiple heat sinks and coils 1032 that pass through the multiple heat sinks 1031. The indoor heat exchanger 15 functions as an evaporator or a radiator depending on the operating state of the indoor unit 100, so that the refrigerant flowing in the coils can exchange heat with the air passing through the indoor heat exchanger 15.

[0073] The indoor fan 16 is an adjustable-speed DC inverter fan, and its operating parameters can be adjusted as needed. The air outlet 10A is equipped with a static pressure detection device (not shown in the figure) to detect the external static pressure value corresponding to the air outlet 10A. The indoor fan 16 is located approximately in the central part inside the housing 101, and is a slender, approximately cylindrical cross-flow fan along the length (left-right direction) of the indoor unit 100. By rotating the indoor fan 16, indoor air is drawn in from the air intake 10B, passes through the air filter, and then passes through the indoor heat exchanger 15 to generate conditioned air, which is then blown out of the room from the air outlet 10A. The higher the rotational speed of the indoor fan 16, the greater the volume of conditioned air blown out from the air outlet 10A.

[0074] This invention primarily addresses the critical parameter of system pressure, which requires close monitoring and control to ensure system reliability in harsh, high-temperature environments. Conventional control methods rely on the coil temperature of the heat exchanger to indirectly monitor system pressure. However, the coil temperature takes time to stabilize, inevitably resulting in a lag. Furthermore, for large units, the connecting pipes between the indoor and outdoor units are quite long (e.g., 50m or 100m), leading to slower system stabilization and even slower pipe temperature stabilization, further exacerbating the lag. This lag in pipe temperature readings can prevent the unit from making timely and effective judgments and actions. In harsh, high-temperature environments, failure to adjust promptly often results in system instability and frequent protective shutdowns. The air conditioner provided by this invention, through pressure-superheat, pressure-frequency, and pressure ratio control modes, can promptly detect system pressure and make corresponding control adjustments, effectively solving the problem of lag in external coil temperature response. This avoids lag in adjustment affecting the sustainable and stable operation of the system and reduces unnecessary protective shutdowns.

[0075] Specifically, the controller in the air conditioner is configured to: when the ambient temperature value detected by the ambient temperature sensor is greater than or equal to a preset ambient temperature threshold, acquire the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor; compare the exhaust pressure value with a number of pre-stored pressure ranges to adjust the operating frequency of the compressor according to the comparison result; calculate the pressure ratio between the exhaust pressure value and the intake pressure value; and compare the pressure ratio with a number of pre-stored ratio thresholds to adjust the opening of the electronic expansion valve according to the comparison result.

[0076] For example, see Figure 5 , Figure 5 This is a first workflow diagram of the controller in an air conditioner provided in an embodiment of the present invention. The controller is configured to execute steps S11 to S16. During unit operation, the ambient temperature value is detected by an ambient temperature sensor to determine whether it is a severe operating condition. When the ambient temperature value is greater than or equal to the ambient temperature threshold, it indicates that the air conditioning unit is in a severe operating condition, and the unit enters the pressure control mode. When the ambient temperature value is less than the ambient temperature threshold, the air conditioner is controlled according to the conventional mode, which is the conventional control mode of air conditioners in the prior art, and will not be described in detail here. It is worth noting that the ambient temperature threshold is a high-temperature severe ambient temperature set by the designer according to the actual situation, such as 48°C for cooling and 30°C for heating, etc., and is not specifically limited here.

[0077] For example, when the air conditioner is in a high-temperature environment, the first pressure sensor detects the exhaust pressure value and the second pressure sensor detects the intake pressure value. At this time, the controller enters a "pressure-frequency control mode" and a "pressure ratio control mode" respectively. To avoid conflicts between these two control modes, their execution priority levels need to be preset, such as setting the priority of the pressure-frequency control mode higher than that of the pressure ratio control mode. In the pressure-frequency control mode, the exhaust pressure value is compared with several pre-stored pressure ranges to adjust the compressor's operating frequency based on the comparison results. In the pressure ratio control mode, the pressure ratio between the exhaust pressure value and the intake pressure value is calculated; the pressure ratio is compared with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results.

[0078] Specifically, the pressure range includes a frequency-restricted pressure range, a frequency-reduced pressure range, and a shutdown pressure range; therefore, the controller is further configured to: control the compressor to maintain its current operating frequency when the exhaust pressure values ​​obtained within a certain period of time are all within the frequency-restricted pressure range; reduce the operating frequency of the compressor when the exhaust pressure values ​​obtained within a certain period of time are all within the frequency-reduced pressure range; and control the compressor to shut down when the exhaust pressure values ​​obtained within a certain period of time are all within the shutdown pressure range.

[0079] For example, see Figure 6 , Figure 6This is a second workflow diagram of the controller in an air conditioner provided in an embodiment of the present invention. Step S14 specifically includes steps S141 to S146, at which point the air conditioner enters the pressure-frequency control mode. In this embodiment, several pressure ranges are pre-defined, which are divided by several pressure thresholds. For example, the pressure thresholds include a first pressure threshold Pa, a second pressure threshold Pb, and a second pressure threshold Pc. The three pressure thresholds satisfy: Pa < Pb < Pc. Therefore, the frequency-restricted pressure range is: Pa ≤ P ≤ Pb, the frequency-reduced pressure range is: Pb < P ≤ Pc, and the shutdown pressure range is: Pc < P, where P is the detected real-time pressure value (exhaust pressure value). In steps S141 to S142, when the detected exhaust pressure values ​​are all within the frequency-restricted pressure range, i.e., satisfying: Pa ≤ P ≤ Pb, and this condition is maintained for a certain period, it indicates that the compressor's operating frequency is appropriate. Therefore, the compressor is prohibited from increasing / decreasing its frequency and maintains the current operating frequency. In steps S143-S144, when the detected exhaust pressure values ​​are all within the frequency reduction pressure range (i.e., Pb < P ≤ Pc) and this condition is maintained for a certain period of time, it indicates that the compressor's operating frequency is high. The compressor then reduces its frequency until the detected exhaust pressure value is less than the first pressure threshold (i.e., P < Pa), at which point the frequency reduction action is released. In steps S145-S146, when the detected exhaust pressure values ​​are all within the shutdown pressure range (i.e., Pc < P) and this condition is maintained for a certain period of time, it indicates that the compressor's operating frequency is very high. Continuing to operate at this frequency could easily damage the compressor, so the compressor enters shutdown protection mode.

[0080] Specifically, the ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold, and the controller is further configured to: increase the opening of the electronic expansion valve when the pressure ratio is greater than the first ratio threshold; control the electronic expansion valve to remain at the current opening when the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold; and decrease the opening of the electronic expansion valve when the pressure ratio is less than the second ratio threshold.

[0081] For example, see Figure 7 , Figure 7This is a third workflow diagram of the controller in an air conditioner provided in this embodiment of the invention. Step S16 specifically includes steps S161 to S166, at which point the air conditioner enters the pressure ratio control mode. In this embodiment of the invention, the ratio threshold includes a first ratio threshold a_max and a second ratio threshold a_min, where the first ratio threshold a_max is greater than the second ratio threshold a_min. Based on the discharge pressure value Ph (high pressure) at the compressor discharge port and the suction pressure value PL (low pressure) at the suction port, the unit automatically calculates its pressure ratio a. The relationship is: a = Ph / PL. In steps S161 to S162, when the pressure ratio is greater than the first ratio threshold, i.e., a > a_max, it indicates that the liquid discharged by the compressor is in a high-pressure state, and the electronic expansion valve needs to be opened a certain number of steps from the current position to ensure that the high-pressure liquid after the action of the electronic expansion valve can be converted into low-pressure liquid. At this time, the valve opening of the adjusted electronic expansion valve needs to be less than or equal to the maximum operating opening of the electronic expansion valve. In steps S163-S164, when the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold, i.e., a_min ≤ a ≤ a_max, the electronic expansion valve maintains its current opening. In steps S165-S166, when the pressure ratio is less than the second ratio threshold, i.e., a < a_min, the electronic expansion valve closes a certain number of steps from its current position. At this time, the adjusted valve opening of the electronic expansion valve needs to be greater than or equal to the minimum operating opening of the electronic expansion valve.

[0082] Specifically, the controller is further configured to: obtain the corresponding high-pressure correction temperature based on the exhaust pressure value; calculate the difference between the compressor's exhaust temperature and the high-pressure correction temperature as a target superheat, and calculate the actual superheat; compare the target superheat and the actual superheat to adjust the opening of the electronic expansion valve based on the comparison result.

[0083] For example, see Figure 8 , Figure 8This is the fourth workflow diagram of the controller in the air conditioner provided in this embodiment of the invention. After executing step S13, the controller is also configured to execute steps S17 to S19. At this time, the air conditioner also includes a "pressure-superheat control mode", which has the lowest priority. The unit judges and executes relevant instructions based on real-time pressure detection parameters. The designer establishes a pressure range-saturation temperature database in the program during the development stage based on the actual operation of the unit. Because the pressure detection sensitivity is high, and the actual system pressure (characterized by the exhaust pressure value) is also in a dynamic equilibrium within a certain fluctuation range, pressure range control within a certain range is more conducive to the stable operation of the unit and avoids unnecessary frequent adjustments. The pressure zoning design is shown in Table 1. If the detected pressure is within a certain pressure range, it is ideally assumed that the saturation temperature Tb corresponding to the pressure within the target pressure range is the same.

[0084] Table 1. Mapping relationship between pressure range, saturation temperature, and high-pressure correction temperature

[0085] [P1, P2) Tb1 Tx1 [P2, P3) Tb2 Tx2 [P3, P4) Tb3 Tx3 …… …… ……

[0086] For example, the pressure range and saturation temperature Tb are a database established by the designer during the development phase, with a one-to-one correspondence. The values ​​of the pressure range can be preset based on empirical values, which will not be elaborated here. The high-pressure correction temperature Tx is a corresponding revision of the saturation temperature based on actual development conditions, facilitating more accurate and convenient control and operation of the unit. The relationship is: Tbn = K * Txn + B, where K is a coefficient, B is the intercept, and the values ​​of K and B can be set based on empirical values, without specific limitations here. n is the number of pressure ranges, n = 1, 2, 3, ... Therefore, the detected pressure P and the high-pressure correction temperature Tx are in one-to-one correspondence. In high-temperature and harsh ambient temperatures, a new pressure control mode is entered. The previously lagging coil temperature no longer participates in superheat control. That is, the unit no longer uses the coil temperature as a detection parameter for logic control, but instead uses the detected high-pressure Ph and its converted high-temperature correction temperature Tx fed back to the unit as a detection parameter for logic control.

[0087] It's worth noting that the conventional superheat calculation is: Superheat = Exhaust Temperature - Coil Temperature, where the coil temperature is the high-pressure side coil temperature. For example, the outdoor heat exchanger coil is selected for cooling, and the indoor heat exchanger coil is selected for heating. In the pressure-superheat control mode provided in this embodiment of the invention, the superheat calculation is: Superheat = Exhaust Temperature - High-Pressure Correction Temperature Tx. In this case, the coil temperature is only used as a reference parameter and is no longer involved in superheat control. However, the relevant coil temperature protection remains effective and is still executed according to the conventional control method. For example, when exhaust frequency limiting is triggered, the unit performs frequency limiting action.

[0088] For example, the pressure-superheat control mode during unit operation is as follows: Target superheat = Exhaust temperature - High-pressure correction temperature Tx. In this mode, a target pressure range is obtained from several preset pressure ranges based on the exhaust pressure value; each pressure range corresponds to a high-pressure correction temperature; based on the high-pressure correction temperature obtained from the target pressure range, the difference between the compressor's exhaust temperature and the high-pressure correction temperature is calculated as the target superheat, and the actual superheat is also calculated; the target superheat and the actual superheat are compared, and the opening of the electronic expansion valve is adjusted according to the comparison result. The control of the electronic expansion valve is the same as conventional control methods, as described in [reference needed]. Figure 9 , Figure 9 This is the fifth working flowchart of the controller in the air conditioner provided in the embodiment of the present invention. When the actual superheat is greater than the target superheat, the opening of the electronic expansion valve is increased; when the actual superheat is less than or equal to the target superheat, the opening of the electronic expansion valve is decreased.

[0089] Compared to existing technologies, the air conditioner disclosed in this invention, by installing a first pressure sensor at the compressor's exhaust port and a second pressure sensor at the compressor's intake port, acquires the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor in high-temperature environments. The exhaust pressure value is compared with several pressure ranges as the system pressure to adjust the compressor's operating frequency based on the comparison results. Furthermore, the pressure ratio between the exhaust and intake pressure values ​​is calculated and compared with several ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results. By detecting real-time system pressure, the unit can promptly adjust relevant parameters based on real-time pressure parameters and their corresponding correction temperatures, effectively solving the problem of lag in coil temperature response, avoiding the impact of lag adjustment on the system's sustainable and stable operation, and reducing unnecessary protective shutdowns.

[0090] See Figure 10 , Figure 10 This is a flowchart of an indoor fan speed control method for an air conditioner according to an embodiment of the present invention. The air conditioner includes a first pressure sensor disposed at the compressor exhaust port and a second pressure sensor disposed at the compressor intake port. The first sensor is used to detect the exhaust pressure value at the exhaust port, and the second sensor is used to detect the intake pressure value at the intake port. Therefore, the air conditioner control method includes:

[0091] S1. When the ambient temperature value is greater than or equal to the preset ambient temperature threshold, acquire the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor.

[0092] S2. Compare the exhaust pressure value with several pre-stored pressure ranges to adjust the operating frequency of the compressor based on the comparison results;

[0093] S3. Calculate the pressure ratio between the exhaust pressure value and the intake pressure value;

[0094] S4. Compare the pressure ratio with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve in the air conditioner according to the comparison result.

[0095] Specifically, the pressure range includes a frequency-restricted pressure range, a frequency-reduced pressure range, and a shutdown pressure range; therefore, adjusting the compressor's operating frequency based on the comparison results includes: when the exhaust pressure values ​​obtained within a certain period are all within the frequency-restricted pressure range, controlling the compressor to maintain the current operating frequency; when the exhaust pressure values ​​obtained within a certain period are all within the frequency-reduced pressure range, reducing the compressor's operating frequency; and when the exhaust pressure values ​​obtained within a certain period are all within the shutdown pressure range, controlling the compressor to shut down.

[0096] Specifically, the ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold; then, adjusting the opening of the electronic expansion valve in the air conditioner according to the comparison result includes: increasing the opening of the electronic expansion valve when the pressure ratio is greater than the first ratio threshold; controlling the electronic expansion valve to remain unchanged at the current opening when the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold; and decreasing the opening of the electronic expansion valve when the pressure ratio is less than the second ratio threshold.

[0097] Specifically, the method further includes: obtaining the corresponding high-pressure correction temperature based on the exhaust pressure value; calculating the difference between the compressor's exhaust temperature and the high-pressure correction temperature as the target superheat, and calculating the actual superheat; comparing the target superheat and the actual superheat to adjust the opening of the electronic expansion valve based on the comparison result.

[0098] Specifically, obtaining the corresponding high-pressure correction temperature based on the exhaust pressure value includes: obtaining a target pressure range from a preset number of pressure ranges based on the exhaust pressure value; wherein each pressure range corresponds to a high-pressure correction temperature; and obtaining the corresponding high-pressure correction temperature based on the target pressure range.

[0099] It is worth noting that the specific working process of the air conditioner control method described in the embodiments of the present invention can be referred to the working process of the controller in the air conditioner described in the above embodiments, and will not be repeated here.

[0100] Compared to existing technologies, the air conditioner control method disclosed in this invention, by setting a first pressure sensor at the compressor's exhaust port and a second pressure sensor at the compressor's intake port, acquires the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor in a high-temperature environment. The exhaust pressure value is compared with several pressure ranges as the system pressure to adjust the compressor's operating frequency based on the comparison results. Furthermore, the pressure ratio between the exhaust pressure value and the intake pressure value is calculated and compared with several ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results. By detecting the real-time system pressure, the unit can promptly adjust relevant parameters based on the real-time pressure parameters and their corresponding correction temperatures, effectively solving the problem of lag in coil temperature response, avoiding the impact of lag adjustment on the system's sustainable and stable operation, and reducing unnecessary protective shutdowns.

[0101] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An air conditioner, characterized in that, include: The refrigerant circuit circulates sequentially through the compressor, condenser, electronic expansion valve, and evaporator in the refrigeration cycle. One of the condenser and the evaporator is an outdoor heat exchanger, and the other is an indoor heat exchanger. The compressor is equipped with an intake port and an exhaust port. A first pressure sensor is located at the exhaust port of the compressor and is used to detect the exhaust pressure value at the exhaust port. The second pressure sensor is located at the air intake of the compressor and is used to detect the air intake pressure value at the air intake. Ambient temperature sensor, used to detect ambient temperature values; A controller, which controls at least the compressor and the electronic expansion valve, is configured to: When the ambient temperature value detected by the ambient temperature sensor is greater than or equal to the preset ambient temperature threshold, the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor are obtained. The discharge pressure value is compared with several pre-stored pressure ranges to adjust the operating frequency of the compressor based on the comparison results. Calculate the pressure ratio between the exhaust pressure value and the intake pressure value; The pressure ratio is compared with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve based on the comparison results. The pressure range includes a frequency-blocking pressure range, a frequency-reducing pressure range, and a shutdown pressure range; therefore, the controller is further configured to: When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency restriction pressure range, the compressor is controlled to maintain the current operating frequency. When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency reduction pressure range, the operating frequency of the compressor is reduced. When the exhaust pressure values ​​obtained within a certain period of time are all within the shutdown pressure range, the compressor is controlled to shut down.

2. The air conditioner as described in claim 1, characterized in that, The ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold, and the controller is further configured to: When the pressure ratio is greater than the first ratio threshold, the opening of the electronic expansion valve is increased; When the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold, the electronic expansion valve is controlled to remain at the current opening degree. When the pressure ratio is less than the second ratio threshold, the opening of the electronic expansion valve is reduced.

3. The air conditioner as described in claim 1, characterized in that, The controller is also configured to: The corresponding high-pressure correction temperature is obtained based on the exhaust pressure value; The difference between the compressor's exhaust temperature and the high-pressure correction temperature is calculated as the target superheat, and the actual superheat is also calculated. The target superheat is compared with the actual superheat, and the opening of the electronic expansion valve is adjusted according to the comparison result.

4. The air conditioner as described in claim 3, characterized in that, The controller is also configured to: Based on the exhaust pressure value, a target pressure range is obtained from a preset number of pressure ranges; wherein, each pressure range corresponds to a high-pressure correction temperature; The corresponding high-pressure correction temperature is obtained based on the target pressure range.

5. An air conditioner control method, characterized in that, The air conditioner includes a first pressure sensor located at the compressor exhaust port and a second pressure sensor located at the compressor intake port. The first pressure sensor is used to detect the exhaust pressure value at the exhaust port, and the second pressure sensor is used to detect the intake pressure value at the intake port. Therefore, the air conditioner control method includes: When the ambient temperature value is greater than or equal to the preset ambient temperature threshold, the exhaust pressure value detected by the first pressure sensor and the intake pressure value detected by the second pressure sensor are obtained. The discharge pressure value is compared with several pre-stored pressure ranges to adjust the operating frequency of the compressor based on the comparison results. Calculate the pressure ratio between the exhaust pressure value and the intake pressure value; The pressure ratio is compared with several pre-stored ratio thresholds to adjust the opening of the electronic expansion valve in the air conditioner based on the comparison results. The pressure range includes a frequency-restricted pressure range, a frequency-reduced pressure range, and a shutdown pressure range; therefore, adjusting the compressor's operating frequency based on the comparison results includes: When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency restriction pressure range, the compressor is controlled to maintain the current operating frequency. When the exhaust pressure values ​​obtained within a certain period of time are all within the frequency reduction pressure range, the operating frequency of the compressor is reduced. When the exhaust pressure values ​​obtained within a certain period of time are all within the shutdown pressure range, the compressor is controlled to shut down.

6. The air conditioner control method as described in claim 5, characterized in that, The ratio threshold includes a first ratio threshold and a second ratio threshold, wherein the first ratio threshold is greater than the second ratio threshold; therefore, adjusting the opening of the electronic expansion valve in the air conditioner according to the comparison result includes: When the pressure ratio is greater than the first ratio threshold, the opening of the electronic expansion valve is increased; When the pressure ratio is less than or equal to the first ratio threshold and greater than or equal to the second ratio threshold, the electronic expansion valve is controlled to remain at the current opening degree. When the pressure ratio is less than the second ratio threshold, the opening of the electronic expansion valve is reduced.

7. The air conditioner control method as described in claim 5, characterized in that, The method further includes: The corresponding high-pressure correction temperature is obtained based on the exhaust pressure value; The difference between the compressor's exhaust temperature and the high-pressure correction temperature is calculated as the target superheat, and the actual superheat is also calculated. The target superheat is compared with the actual superheat, and the opening of the electronic expansion valve is adjusted according to the comparison result.

8. The air conditioner control method as described in claim 7, characterized in that, The step of obtaining the corresponding high-pressure correction temperature based on the exhaust pressure value includes: Based on the exhaust pressure value, a target pressure range is obtained from a preset number of pressure ranges; wherein, each pressure range corresponds to a high-pressure correction temperature; The corresponding high-pressure correction temperature is obtained based on the target pressure range.

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