Compressor oil level determination method, air conditioner, controller and storage medium

Abstract

Embodiments of the present application provide a compressor oil level determination method, an air conditioner, a controller and a storage medium, and relate to the technical field of air conditioners. The method is applied to a controller in an air conditioner, and comprises the following steps: obtaining an oil temperature on a connection side of an expansion valve and a gas-liquid separator, and an exhaust temperature of a compressor; setting a plurality of temperature intervals based on the exhaust temperature; determining a temperature interval in which the oil temperature is located; in a case where it is determined that the oil temperature is in a certain temperature interval in a preset period, controlling the expansion valve to act every preset time until it is determined that the oil temperature is in another temperature interval; obtaining an opening degree of the current expansion valve and a frequency of the compressor; and determining the height of the compressor oil surface based on the opening degree of the current expansion valve and the frequency of the compressor. The embodiments of the present application realize determination of the height of the compressor oil surface at low cost, and ensure that the refrigeration oil discharged by the compressor can be normally returned.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, in particular to a compressor oil level determination method, an air conditioner, a controller and a storage medium. BACKGROUND

[0002] Long-pipe air conditioners and air conditioners connected with multiple indoor units may cause insufficient compressor oil due to oil retention in refrigerant pipes or indoor units. When the air conditioner is connected with multiple compressors, oil imbalance between the compressors may also cause insufficient compressor oil. For the above air conditioners, the effect of preventing insufficient compressor oil can be achieved by detecting the oil level related to the compressor oil volume, returning the oil retained in the refrigerant pipes and indoor units to the compressor for oil return operation or performing oil equalization operation to achieve compressor oil equalization.

[0003] The prior art achieves the above effect by providing a float switch or a capacitive sensor inside the compressor for detecting the oil level of the compressor. However, the above method requires a special compressor with an internal oil level detection device, which increases the cost of the compressor and has poor universality. In addition, the above method also recovers the refrigeration oil discharged from the compressor through an oil separator, and returns the recovered oil to the suction side of the compressor through a capillary tube to prevent the oil from flowing out of the outdoor unit and to ensure the oil level of the compressor. However, due to the flow characteristics of the capillary tube for oil return, it may not be possible to achieve sufficient oil return to the compressor. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a compressor oil level determination method, an air conditioner, a controller and a storage medium to determine the oil level of the compressor at a low cost and ensure that the refrigeration oil discharged from the compressor can be normally returned.

[0005] To achieve the above purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0006] In a first aspect, the embodiments of the present application provide a compressor oil level determination method applied to a controller in an air conditioner, wherein the controller is electrically connected with an expansion valve and a compressor in the air conditioner, the expansion valve is arranged between an oil separator and a gas-liquid separator in the air conditioner, and the method comprises:

[0007] Obtaining the oil temperature on the connection side of the expansion valve and the gas-liquid separator, and the discharge temperature of the compressor;

[0008] Setting multiple temperature intervals based on the discharge temperature;

[0009] determining a temperature interval in which the oil temperature is located, in a case where it is determined that the oil temperature is located in a certain one of the temperature intervals in a preset period, controlling the expansion valve to act every preset time until it is determined that the oil temperature is located in another one of the temperature intervals, obtaining a current opening degree of the expansion valve and a frequency of the compressor, and determining the height of the oil surface of the compressor based on the current opening degree of the expansion valve and the frequency of the compressor.

[0010] In an optional embodiment, the expansion valve and the gas-liquid separator connection side are provided with an oil temperature sensor, an exhaust temperature sensor is arranged on the exhaust side of the compressor, and the controller is electrically connected with the oil temperature sensor and the exhaust temperature sensor.

[0011] The step of obtaining the oil temperature of the expansion valve and the gas-liquid separator connection side and the exhaust temperature of the compressor comprises:

[0012] The oil temperature of the expansion valve and the gas-liquid separator connection side detected by the oil temperature sensor and the exhaust temperature of the compressor detected by the exhaust temperature sensor are obtained.

[0013] In an optional embodiment, the plurality of temperature intervals comprises a first temperature interval and a second temperature interval, and the step of setting a plurality of temperature intervals based on the exhaust temperature comprises:

[0014] A difference value between the exhaust temperature and a preset temperature is obtained, and the difference value is taken as a first temperature value.

[0015] A sum value of the exhaust temperature and a preset sensor error compensation value is obtained, and the sum value is taken as a second temperature value.

[0016] The temperature interval in which the oil temperature is greater than the first temperature value and less than the second temperature value is set as the first temperature interval.

[0017] The temperature interval in which the oil temperature is less than or equal to the first temperature value is set as the second temperature interval.

[0018] In an optional embodiment, the step of determining a temperature interval in which the oil temperature is located, in a case where it is determined that the oil temperature is located in a certain one of the temperature intervals in a preset period, controlling the expansion valve to act every preset time until it is determined that the oil temperature is located in another one of the temperature intervals, obtaining a current opening degree of the expansion valve and a frequency of the compressor, and determining the height of the oil surface of the compressor based on the current opening degree of the expansion valve and the frequency of the compressor comprises:

[0019] determining a temperature interval of the oil temperature, in a case where it is determined that the oil temperature is in a first temperature interval in a preset period, controlling the expansion valve to be operated at a preset opening degree every preset time until it is determined that the oil temperature is in a second temperature interval, obtaining a current opening degree of the expansion valve and a frequency of the compressor;

[0020] determining a height of the compressor oil surface based on the current opening degree of the expansion valve and the frequency of the compressor.

[0021] In an optional embodiment, the step of determining a temperature interval of the oil temperature, in a case where it is determined that the oil temperature is in a certain one of the temperature intervals in a preset period, controlling the expansion valve to be operated every preset time until it is determined that the oil temperature is in another one of the temperature intervals, obtaining a current opening degree of the expansion valve and a frequency of the compressor, and determining a height of the compressor oil surface based on the current opening degree of the expansion valve and the frequency of the compressor, further comprises:

[0022] determining a temperature interval of the oil temperature, in a case where it is determined that the oil temperature is in a second temperature interval in a preset period, controlling the expansion valve to be operated at a preset opening degree every preset time until it is determined that the oil temperature is in a first temperature interval, obtaining a current opening degree of the expansion valve and a frequency of the compressor;

[0023] determining a height of the compressor oil surface based on the current opening degree of the expansion valve and the frequency of the compressor.

[0024] In an optional embodiment, the method further comprises:

[0025] setting the temperature interval in which the oil temperature is greater than or equal to the second temperature value as a third temperature interval.

[0026] In an optional embodiment, the method further comprises:

[0027] determining a temperature interval of the oil temperature, in a case where the oil temperature is in a third temperature interval, determining that the oil temperature sensor is abnormal.

[0028] In a second aspect, an embodiment of the present application provides an air conditioner, comprising a plurality of outdoor units and a controller, each of the outdoor units being connected in parallel;

[0029] Each of the outdoor units comprises a compressor, a four-way valve and a gas-liquid separator, the compressor, the four-way valve and the gas-liquid separator are sequentially connected, an oil separator is connected in series between the compressor and the four-way valve, an expansion valve is connected in series between the oil separator and the gas-liquid separator, an oil temperature sensor is arranged at a connecting side of the expansion valve and the gas-liquid separator, an exhaust temperature sensor is arranged at an exhaust side of the compressor, the controller is electrically connected with the expansion valve and the compressor, and the controller is electrically connected with the oil temperature sensor and the exhaust temperature sensor;

[0030] The controller is configured to execute the compressor oil level determination method provided in the first aspect and / or the possible implementation manners of the first aspect, to obtain the oil temperature at the connecting side of the expansion valve and the gas-liquid separator, and the exhaust temperature of the compressor, set a plurality of temperature intervals based on the exhaust temperature, determine the temperature interval in which the oil temperature is located, control the expansion valve to act every preset time until it is determined that the oil temperature is located in another temperature interval, obtain the current opening degree of the expansion valve and the frequency of the compressor, and determine the height of the oil surface of the compressor based on the current opening degree of the expansion valve and the frequency of the compressor.

[0031] In a third aspect, an embodiment of the present application provides a controller, comprising a memory and a processor.

[0032] The memory is configured to store a computer program.

[0033] The processor is configured to execute the computer program to implement the compressor oil level determination method provided in the first aspect and / or the possible implementation manners of the first aspect.

[0034] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the compressor oil level determination method provided in the first aspect and / or the possible implementation manners of the first aspect.

[0035] The beneficial effects of the embodiments of the present application include, for example:

[0036] The compressor oil level determination method, air conditioner, controller, and storage medium provided in this invention embodiment do not require additional special components such as float switches or capacitive sensors on the compressor. Only an adjustable-flow expansion valve needs to be installed between the oil separator and the gas-liquid separator in the air conditioner. Multiple temperature ranges are set based on the compressor's discharge temperature. The oil temperature on the connection side between the expansion valve and the gas-liquid separator is determined within the specified temperature range. The expansion valve is then controlled to adjust its opening at preset intervals based on the corresponding temperature range. This relatively simple method of controlling the expansion valve ultimately achieves compressor oil level determination based on the relationship between the expansion valve's opening and the compressor's operating frequency. The overall cost is low, and the method is unaffected by the compressor oil level during startup, normal operation, or compressor operating frequency. It ensures that the refrigerant oil discharged from the compressor can return normally, achieving compatibility with compressors of other air conditioner models.

[0037] Furthermore, during the compressor start-up phase, especially during prolonged shutdowns in low-temperature environments and in a liquid-accumulated start-up state, by controlling the expansion valve to operate at preset intervals to adjust its opening, even if foaming occurs due to refrigerant dissolution in the compressor oil during the start-up phase, resulting in a significant amount of compressor oil being carried out of the compressor, and the high and low pressure difference being small, the compressor oil discharged from the compressor can still be guaranteed to return normally without requiring special control measures such as lowering the compressor operating frequency or requiring a long start-up time. This ensures that the basic functional requirements of the air conditioner are met.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 An exemplary structural diagram of a conventional oil level detection sensor-integrated compressor provided by an embodiment of the present invention is shown;

[0041] Figure 2 An exemplary structural diagram of a capillary oil return circuit provided by an embodiment of the present invention is shown;

[0042] Figure 3 An exemplary structural diagram of an air conditioner provided by an embodiment of the present invention is shown;

[0043] Figure 4 A flowchart illustrating a compressor oil level determination method provided by an embodiment of the present invention is shown.

[0044] Figure 5 An exemplary structural diagram is shown, illustrating the change in the oil level state inside the oil separator when the opening of the expansion valve in an air conditioner is adjusted, according to an embodiment of the present invention.

[0045] Figure 6 This is a second exemplary structural diagram illustrating the change in oil level state in an oil separator when the opening of the expansion valve in an air conditioner is adjusted, according to an embodiment of the present invention.

[0046] Figure 7 This illustration shows the relationship between the compressor oil level and the amount of refrigerant oil discharged by the compressor in an air conditioner according to an embodiment of the present invention, as well as the relationship between the amount of refrigerant oil discharged by the compressor and the opening and closing of the expansion valve.

[0047] Figure 8 This is a second schematic flowchart of a compressor oil level determination method provided by an embodiment of the present invention;

[0048] Figure 9 The third schematic flowchart of a compressor oil level determination method provided by an embodiment of the present invention is shown;

[0049] Figure 10 The fourth flowchart illustrates a method for determining the oil level of a compressor according to an embodiment of the present invention.

[0050] Figure 11 The fifth flowchart illustrates a method for determining the oil level of a compressor according to an embodiment of the present invention.

[0051] Figure 12 This is a sixth flowchart illustrating a method for determining the oil level of a compressor according to an embodiment of the present invention;

[0052] Figure 13 The seventh flowchart illustrates a method for determining the oil level of a compressor according to an embodiment of the present invention.

[0053] Icons: 10 - Sensor-integrated compressor; 20 - Oil return circuit using capillary tube; 30 - Air conditioner; 300 - Outdoor unit; 301 - Compressor; 302 - Oil separator; 303 - Four-way valve; 304 - Outdoor heat exchanger; 305 - Expansion valve; 306 - Gas-liquid separator; 310 - Indoor unit. Detailed Implementation

[0054] 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0056] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0058] Air conditioners with long connecting pipes or multiple indoor units may experience insufficient compressor oil levels due to oil stagnation in the refrigerant piping or indoor units. Furthermore, when multiple compressors are connected, uneven oil distribution among them can also cause insufficient compressor oil levels. To address these issues, measures such as monitoring the oil level (related to compressor oil level) and implementing oil return operations (to return stagnant oil from the refrigerant piping and indoor units to the compressor) or oil equalization operations (to ensure uniform compressor oil levels) can prevent insufficient compressor oil levels.

[0059] Please see Figure 1 , Figure 1 This diagram illustrates an exemplary structure of a conventional oil level detection sensor-integrated compressor 10 according to an embodiment of the present invention. Figure 1As shown, existing technologies achieve the above effect by installing a float switch or capacitive sensor inside the compressor to detect the compressor oil level. However, the above method requires a specially designed compressor with an internal oil level detection device, which leads to increased compressor cost and poor versatility.

[0060] Please see Figure 2 , Figure 2 An exemplary structural diagram of a capillary oil return circuit 20 provided by an embodiment of the present invention is shown. Furthermore, the prior art also utilizes a compressor (e.g., such as...) Figure 2 The refrigeration oil discharged from the compressor 2a) shown passes through an oil separator (e.g., such as...) Figure 2 The oil separator 3a) shown recovers the oil, and the recovered oil passes through a capillary (e.g., as shown) Figure 2 The capillary tube 9a) shown returns to the compressor suction side to suppress oil outflow from the outdoor unit, ensuring the compressor oil level is normal.

[0061] However, due to the flow characteristics of the capillary tube used for oil return, the above-mentioned technology may not be able to achieve sufficient oil return, especially during the compressor start-up phase and when the compressor operates at a high frequency, resulting in more refrigerant oil being discharged. Conversely, when the compressor operates at a low frequency, less refrigerant oil is discharged. In addition, the amount of refrigerant oil discharged will vary depending on the compressor oil level.

[0062] Furthermore, implementing oil return via a capillary tube at a specific flow rate, based on conditions such as compressor oil level, operating frequency, startup phase, and normal operation, presents a significant design challenge. Particularly during compressor startup, when foaming occurs in the dissolved refrigerant in the compressor oil, a considerable amount of oil is carried out of the compressor. Under conditions of small high and low pressure differences, the amount of oil returned via the capillary tube at a specific flow rate cannot be guaranteed to match the design specifications, potentially causing a temporary abnormal drop in the compressor oil level or even compressor malfunction. Therefore, the compressor needs to operate at a lower frequency during startup and require a certain amount of time to start up. The aforementioned methods would affect the basic functions of the air conditioner.

[0063] Based on this, embodiments of the present invention provide a method for determining the oil level of a compressor to solve the above-mentioned problems.

[0064] Please see Figure 3 , Figure 3 An exemplary structural diagram of an air conditioner 30 provided in an embodiment of the present invention is shown, as follows: Figure 3 As shown, the air conditioner 30 is composed of multiple outdoor units 300, including a compressor 301, an oil separator 302, a four-way valve 303, an outdoor heat exchanger 304, an expansion valve 305, and a gas-liquid separator 306, and multiple indoor units 310, including an indoor heat exchanger, connected in parallel.

[0065] Among them, an oil separator 302 is connected in series between the compressor 301 and the four-way valve 303. The oil separator 302 separates the refrigeration oil contained in the refrigerant discharged by the compressor 301, stores the separated oil in the lower part of the oil separator 302, and then sends an appropriate amount back to the gas-liquid separator 306 through the expansion valve 305.

[0066] An oil temperature sensor for detecting refrigerant temperature is installed downstream of expansion valve 305, and an exhaust temperature sensor for detecting the discharged refrigerant temperature is installed on the exhaust side of compressor 301. The opening degree of expansion valve 305 for oil return is controlled according to the detection values ​​of oil temperature sensor and exhaust temperature sensor.

[0067] It should be noted that the amount of refrigeration oil discharged from compressor 301 is related to the oil level inside compressor 301; the higher the oil level, the more oil is discharged, and the lower the oil level, the less oil is discharged. Therefore, this characteristic can be used to estimate the oil level inside the compressor based on the opening of expansion valve 305.

[0068] Furthermore, the air conditioner 30 also includes a controller (not shown in the figure). The controller is used to control the operation of the expansion valve 305, and also to control the opening degree of the expansion valve 305. The controller is connected to the compressor 301 and the expansion valve 305 via a data cable to transmit communication information.

[0069] The controller includes a processor. The processor may include a central processing unit (CPU), a microprocessor, or an application-specific integrated circuit (ASIC), and may be used to perform the corresponding operations described in the controller when the processor executes a program stored in a non-transitory computer-readable medium coupled to the controller. The non-transitory computer-readable storage medium may include magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes), smart cards, or flash memory devices (e.g., erasable programmable read-only memory (EPROM), card, stick, or keyboard drivers).

[0070] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a controller, can implement the compressor oil level determination method provided by the present invention.

[0071] The following description, using the controller of the air conditioner 30 as the executing entity, provides an exemplary description of a compressor oil level determination method provided in this embodiment of the invention. Please refer to [link to relevant documentation]. Figure 4 ,Figure 4 The diagram shows a flowchart of a compressor oil level determination method provided by an embodiment of the present invention.

[0072] like Figure 4 As shown, the above-mentioned compressor oil level determination method is applied to the controller in the air conditioner 30. The controller is electrically connected to the expansion valve 305 and the compressor 301 in the air conditioner 30. The expansion valve 305 is located between the oil separator 302 and the gas-liquid separator 306 in the air conditioner 30. The above method may include the following steps:

[0073] S210 obtains the oil temperature at the connection side of the expansion valve and the gas-liquid separator, as well as the discharge temperature of the compressor.

[0074] The S220 has multiple temperature ranges set based on exhaust temperature.

[0075] S230: Determine the temperature range of the oil temperature. If the oil temperature is determined to be within a certain temperature range in a preset cycle, control the expansion valve to operate at preset intervals until the oil temperature is determined to be in another temperature range. Obtain the current opening degree of the expansion valve and the frequency of the compressor. Based on the current opening degree of the expansion valve and the frequency of the compressor, determine the oil level of the compressor.

[0076] The above steps realize the process of setting an expansion valve between the oil separator and the gas-liquid separator in the air conditioner, and determining the compressor oil level based on the current opening of the expansion valve and the compressor frequency by adjusting the opening of the expansion valve.

[0077] Step S210 involves acquiring the oil temperature at the connection between the expansion valve and the gas-liquid separator, as well as the compressor's discharge temperature. Specifically, acquiring the oil temperature at the connection between the expansion valve and the gas-liquid separator can be achieved by installing an oil temperature sensor at that connection point. Similarly, acquiring the compressor's discharge temperature can be achieved by installing an discharge temperature sensor on the compressor's discharge side.

[0078] After obtaining the oil temperature at the connection side of the expansion valve and the gas-liquid separator, as well as the discharge temperature of the compressor, step S220 is executed to set multiple temperature ranges based on the discharge temperature.

[0079] In this embodiment of the invention, multiple temperature ranges are set based on exhaust temperature. Specifically, this can be achieved by obtaining the difference between the exhaust temperature and a preset temperature, using the difference as a first temperature value; obtaining the sum of the exhaust temperature and a preset sensor error compensation value, using the sum as a second temperature value, so that the temperature range where the oil temperature is greater than the first temperature value and less than the second temperature value is set as the first temperature range, and the temperature range where the oil temperature is less than or equal to the first temperature value is set as the second temperature range.

[0080] For example, if the preset temperature is 5℃, then the first temperature value is exhaust temperature -5℃, and the preset sensor error compensation value is α, then the second temperature value is exhaust temperature + α. Therefore, the first temperature range is exhaust temperature -5 < oil temperature < exhaust temperature + α, and the second temperature range is oil temperature ≤ exhaust temperature -5℃.

[0081] It should be noted that the above step of selecting the first temperature value as the difference between the exhaust temperature and the preset temperature means that about 20% of the discharged gaseous refrigerant flow state is regarded as the expansion valve opening being too large.

[0082] In this embodiment of the invention, after setting multiple temperature ranges, step S230 is executed to determine the temperature range in which the oil temperature is located. If it is determined that the oil temperature is in a certain temperature range in a preset cycle, the expansion valve is controlled to operate at preset intervals until it is determined that the oil temperature is in another temperature range. The opening degree of the current expansion valve and the frequency of the compressor are obtained, and the oil level of the compressor is determined based on the opening degree of the current expansion valve and the frequency of the compressor.

[0083] In this embodiment of the invention, when the expansion valve actuates to adjust its opening, the change in the oil level state inside the oil separator can be as follows: Figure 5 and Figure 6 As shown. Among them, Figure 5 This refers to the state where the refrigeration oil discharged from the compressor 301 accumulates in the oil separator 302. At this time, relative to the refrigeration oil discharged from the compressor 301, the opening of the expansion valve 305 is either too small or just right. Figure 6 The state is that all the refrigeration oil discharged from the compressor 301 is discharged from the oil separator 302. At this time, the expansion valve 305 is too open relative to the refrigeration oil discharged from the compressor 301.

[0084] Based on the state of the refrigeration oil accumulated in the oil separator 302 and the state of all the refrigeration oil discharged from the compressor 301 discharged from the oil separator 302, the opening degree of the expansion valve 305 can be adjusted by controlling the expansion valve 305 to operate at preset intervals. Figure 5 and Figure 6 The two states of the oil separator 302 are repeatedly observed to determine the opening degree of the expansion valve corresponding to the amount of refrigeration oil discharged by the compressor 301.

[0085] For example, if the condensing temperature is 55°C, the evaporating temperature is 8°C, and the refrigerant discharge temperature from compressor 301 is 95°C, then the refrigerant and refrigeration oil temperature inside oil separator 302 is also 95°C. Figure 5 As shown, when a certain amount of refrigeration oil accumulates inside the oil separator 302, the expansion valve 305 only passes through the refrigeration oil and does not discharge gaseous refrigerant. Even if the refrigeration oil depressurizes from the discharge pressure to the suction pressure, there will be no temperature change. At this time, the oil temperature on the connection side between the expansion valve 305 and the gas-liquid separator 306 is about 95°C.

[0086] Furthermore, such as Figure 6 As shown, when there is no refrigeration oil accumulation in the oil separator 302, the separated refrigeration oil mixes with the discharged gaseous refrigerant at 95°C and is depressurized through the expansion valve 305. Depending on the mixing ratio of refrigerant and refrigeration oil, the oil temperature on the connection side between the expansion valve 305 and the gas-liquid separator 306 is approximately between 72°C and 95°C.

[0087] Based on this, the opening degree of the expansion valve 305 corresponding to the amount of oil discharged can be determined by the temperature difference caused by the accumulation of refrigeration oil in the oil separator 302.

[0088] After obtaining the current opening degree of the expansion valve 305 and the frequency of the compressor 301, the oil level of the compressor 301 can be estimated by the opening degree of the expansion valve 305.

[0089] In this embodiment of the invention, the amount of refrigeration oil discharged by compressor 301 is related to the oil level of compressor 301 and the frequency of compressor 301. That is, the higher the oil level of compressor 301 and the higher the frequency of compressor 301, the more oil is discharged.

[0090] The relationship between the compressor oil level and the amount of refrigerant oil discharged from the compressor, as well as the relationship between the amount of refrigerant oil discharged from the compressor and the opening and closing of the expansion valve, can be described as follows: Figure 7 As shown.

[0091] Specifically, such as Figure 7 As shown, point A indicates the compressor oil level is below the normal level, displaying the amount of refrigerant oil discharged during high-frequency compressor operation; point B indicates the compressor oil level is normal, displaying the amount of refrigerant oil discharged during intermediate-frequency compressor operation; point C indicates the compressor oil level is above normal, displaying the amount of refrigerant oil discharged during low-frequency compressor operation; point E indicates the compressor oil level is normal, displaying the amount of refrigerant oil discharged during high-frequency compressor operation; and point F indicates the compressor oil level is above normal, displaying the amount of refrigerant oil discharged during intermediate-frequency compressor operation.

[0092] Furthermore, based on Figure 7The relationship between the compressor oil level and the amount of refrigerant oil discharged from the compressor shows that, in order to achieve a similar amount of refrigerant oil discharge at points A, B, and C, the expansion valve opening should be step D; and in order to achieve a similar amount of refrigerant oil discharge at points E and F, the expansion valve opening should be step G.

[0093] Therefore, when the expansion valve opening is D steps, the compressor oil level can be determined as A (insufficient oil), B (normal oil), or C (excessive oil return) based on the compressor frequency.

[0094] Therefore, by controlling the opening of the expansion valve to ensure that the compressor discharges enough refrigeration oil to return to the suction side (gas-liquid separator), it is possible to determine the compressor oil level based on the current opening of the expansion valve and the compressor frequency.

[0095] The compressor oil level determination method provided in this invention does not require additional special components such as float switches or capacitive sensors on the compressor. It only requires an adjustable flow expansion valve between the oil separator and the gas-liquid separator in the air conditioner. Multiple temperature ranges are set based on the compressor's discharge temperature. The oil temperature on the connection side between the expansion valve and the gas-liquid separator is determined within the specified temperature range. The expansion valve is then controlled to adjust its opening at preset intervals based on the corresponding temperature range. This relatively simple method of controlling the expansion valve ultimately achieves compressor oil level determination based on the relationship between the expansion valve's opening and the compressor's operating frequency. The overall cost is low, and the method is unaffected by the compressor oil level during startup, normal operation, or compressor operating frequency. It ensures that the refrigerant oil discharged from the compressor can return normally, achieving compatibility with compressors of other air conditioner models.

[0096] Furthermore, during the compressor start-up phase, especially during prolonged shutdowns in low-temperature environments and in a liquid-accumulated start-up state, by controlling the expansion valve to operate at preset intervals to adjust its opening, even if foaming occurs due to refrigerant dissolution in the compressor oil during the start-up phase, resulting in a significant amount of compressor oil being carried out of the compressor, and the high and low pressure difference being small, the compressor oil discharged from the compressor can still be guaranteed to return normally without requiring special control measures such as lowering the compressor operating frequency or requiring a long start-up time. This ensures that the basic functional requirements of the air conditioner are met.

[0097] Optionally, the process of obtaining the oil temperature at the connection side of the expansion valve and the gas-liquid separator, as well as the compressor's discharge temperature, can be achieved through the following steps:

[0098] exist Figure 4 Based on this, please refer to Figure 8 , Figure 8This is a second flowchart illustrating a compressor oil level determination method according to an embodiment of the present invention. An oil temperature sensor is installed on the connection side between the expansion valve and the gas-liquid separator, and an exhaust temperature sensor is installed on the exhaust side of the compressor. The controller is electrically connected to the oil temperature sensor and the exhaust temperature sensor. Step S210, which involves obtaining the oil temperature on the connection side between the expansion valve and the gas-liquid separator, and the exhaust temperature of the compressor, includes:

[0099] S211, acquire the oil temperature detected by the oil temperature sensor at the connection side of the expansion valve and the gas-liquid separator, and the exhaust temperature detected by the exhaust temperature sensor at the compressor.

[0100] The above steps achieve the process of obtaining the oil temperature at the connection side of the expansion valve and the gas-liquid separator, as well as the discharge temperature of the compressor.

[0101] Alternatively, the process of setting multiple temperature ranges based on exhaust temperature can be achieved through the following steps:

[0102] exist Figure 8 Based on this, please refer to Figure 9 , Figure 9 This is a third flowchart illustrating a compressor oil level determination method according to an embodiment of the present invention. Multiple temperature ranges are included, comprising a first temperature range and a second temperature range. The steps for setting multiple temperature ranges based on the exhaust temperature include:

[0103] S221, obtain the difference between the exhaust temperature and the preset temperature, and use the difference as the first temperature value.

[0104] S222, obtain the sum of the exhaust temperature and the preset sensor error compensation value, and use the sum as the second temperature value.

[0105] S223, set the temperature range where the oil temperature is greater than the first temperature value and less than the second temperature value as the first temperature range.

[0106] S224, set the temperature range where the oil temperature is less than or equal to the first temperature value as the second temperature range.

[0107] The above steps enable the setting of multiple temperature ranges based on exhaust temperature.

[0108] For example, if the preset temperature is 5℃, then the first temperature value is exhaust temperature -5℃, and the preset sensor error compensation value is α, then the second temperature value is exhaust temperature + α. Therefore, the first temperature range is exhaust temperature -5 < oil temperature < exhaust temperature + α, and the second temperature range is oil temperature ≤ exhaust temperature -5℃.

[0109] Optionally, the oil temperature is determined to be within a certain temperature range. If the oil temperature is consistently within a certain temperature range over a preset period, the expansion valve is controlled to operate at preset intervals until the oil temperature is determined to be in another temperature range. The current opening degree of the expansion valve and the compressor frequency are obtained. The process of determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency can be achieved through the following steps:

[0110] exist Figure 9 Based on this, please refer to Figure 10 , Figure 10 The fourth step of the flowchart illustrating a compressor oil level determination method provided by an embodiment of the present invention is shown. In step S230, the oil temperature is determined to be within a certain temperature range. If the oil temperature is determined to be within a certain temperature range throughout a preset period, the expansion valve is controlled to operate at preset time intervals until the oil temperature is determined to be in another temperature range. The current opening degree of the expansion valve and the compressor frequency are obtained. The step of determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency includes:

[0111] S231, determine the temperature range of the oil temperature. If the oil temperature is determined to be in the first temperature range for a preset period, control the expansion valve to open to a preset degree at preset intervals until the oil temperature is determined to be in the second temperature range, and obtain the current opening degree of the expansion valve and the frequency of the compressor.

[0112] S232 determines the compressor oil level based on the current expansion valve opening and compressor frequency.

[0113] The above steps realize the process of controlling the expansion valve to adjust the opening degree until the oil temperature is determined to be in the second temperature range when the oil temperature is determined to be in the first temperature range throughout the preset cycle, obtaining the current opening degree of the expansion valve and the frequency of the compressor, and finally determining the oil level of the compressor based on the current opening degree of the expansion valve and the frequency of the compressor.

[0114] Optionally, the oil temperature is determined to be within a certain temperature range. If the oil temperature is determined to be within a certain temperature range throughout a preset cycle, the expansion valve is controlled to operate at preset intervals until the oil temperature is determined to be in another temperature range. The current opening degree of the expansion valve and the compressor frequency are obtained. The process of determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency can also be achieved through the following steps:

[0115] exist Figure 9 Based on this, please refer to Figure 11 , Figure 11The fifth step of the flowchart illustrating a compressor oil level determination method according to an embodiment of the present invention is shown. In step S230, the step of determining the temperature range of the oil temperature, and if it is determined that the oil temperature is consistently within a certain temperature range over a preset period, controls the expansion valve to operate at preset time intervals until it is determined that the oil temperature is in another temperature range, and obtains the current opening degree of the expansion valve and the compressor frequency, further includes the step of determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency:

[0116] S233, determine the temperature range of the oil temperature. If the oil temperature is determined to be in the second temperature range for a preset period, control the expansion valve to open to a preset degree at preset intervals until the oil temperature is determined to be in the first temperature range. Obtain the current opening degree of the expansion valve and the frequency of the compressor.

[0117] S234 determines the compressor oil level based on the current expansion valve opening and compressor frequency.

[0118] The above steps realize the process of controlling the expansion valve to adjust its opening until the oil temperature is determined to be in the second temperature range during a preset cycle, obtaining the current opening of the expansion valve and the frequency of the compressor, and finally determining the oil level of the compressor based on the current opening of the expansion valve and the frequency of the compressor.

[0119] For example, based on the previously defined first temperature range of exhaust temperature -5 < oil temperature < exhaust temperature + α, and the second temperature range of oil temperature ≤ exhaust temperature -5, if the preset cycle is set to 5 cycles, the preset time is 1 minute, and the preset opening degree is 5 steps, then the above steps can be illustrated as follows:

[0120] When it is determined that the oil temperature is within the range of exhaust temperature -5 < oil temperature < exhaust temperature + α for 5 cycles, the expansion valve is controlled to open in 5 steps every 1 minute until the oil temperature is determined to be within the range of oil temperature ≤ exhaust temperature -5. The current opening degree of the expansion valve and the frequency of the compressor are obtained and stored.

[0121] When it is determined that the oil temperature is within the range of oil temperature ≤ exhaust temperature -5 for 5 cycles, the expansion valve is controlled to open in 5 steps every 1 minute until the oil temperature is determined to be within the range of exhaust temperature -5 < oil temperature < exhaust temperature + α. The current opening degree of the expansion valve and the frequency of the compressor are obtained and stored.

[0122] Based on the above settings, in order to ensure that the oil temperature is within the specified temperature range, the expansion valve is opened slightly to ensure that there is an oil level inside the oil separator. When it is detected that the specified range is met for more than 5 consecutive cycles, the expansion valve is opened wider to lower the oil level. This operation is repeated to confirm the expansion valve opening corresponding to the amount of refrigeration oil discharged by the compressor.

[0123] Optionally, when the oil temperature is greater than or equal to the second temperature value, there is a possibility that the oil temperature sensor is malfunctioning. Therefore, a third temperature range needs to be set to determine whether the oil temperature sensor is malfunctioning. This process can be achieved through the following steps:

[0124] exist Figure 9 Based on this, please refer to Figure 12 , Figure 12 This is shown as a sixth flowchart illustrating a compressor oil level determination method according to an embodiment of the present invention. The compressor oil level determination method further includes:

[0125] S240 sets the temperature range where the oil temperature is greater than or equal to the second temperature value as the third temperature range.

[0126] Optionally, based on step S240, the process of determining whether the oil temperature sensor is malfunctioning can be implemented through the following steps:

[0127] exist Figure 12 Based on this, please refer to Figure 13 , Figure 13 This is illustrated in the seventh flowchart of a compressor oil level determination method according to an embodiment of the present invention. The compressor oil level determination method further includes:

[0128] S250 determines the temperature range of the oil temperature. If the oil temperature is in the third temperature range, it indicates that the oil temperature sensor is malfunctioning.

[0129] Please see Figure 3 Based on the above method for judging the compressor oil level, an air conditioner 30 is given below. The controller of the air conditioner 30 is used to execute the process steps in the above implementation methods and achieve the corresponding technical effects.

[0130] Specifically, the air conditioner 30 includes multiple outdoor units 300 and a controller, with each outdoor unit 300 connected in parallel.

[0131] Each outdoor unit 300 includes a compressor 301, a four-way valve 303, and a gas-liquid separator 306. The compressor 301, the four-way valve 303, and the gas-liquid separator 306 are connected in sequence. An oil separator 302 is connected in series between the compressor 301 and the four-way valve 303. An expansion valve 305 is connected in series between the oil separator 302 and the gas-liquid separator 306. An oil temperature sensor is installed on the connection side between the expansion valve 305 and the gas-liquid separator 306. An exhaust temperature sensor is installed on the exhaust side of the compressor 301. The controller is electrically connected to the expansion valve 305 and the compressor 301. The controller is also electrically connected to the oil temperature sensor and the exhaust temperature sensor.

[0132] The controller is used to execute the compressor oil level determination method provided in the above-described embodiments of the invention, to obtain the oil temperature at the connection side of the expansion valve 305 and the gas-liquid separator 306, and the discharge temperature of the compressor 301. Based on the discharge temperature, multiple temperature ranges are set, and the temperature range in which the oil temperature is located is determined. If it is determined that the oil temperature is in a certain temperature range in a preset cycle, the expansion valve 305 is controlled to operate at preset intervals until it is determined that the oil temperature is in other temperature ranges. The current opening degree of the expansion valve 305 and the frequency of the compressor 301 are obtained, and the oil level of the compressor 301 is determined based on the current opening degree of the expansion valve 305 and the frequency of the compressor 301.

[0133] Based on the same inventive concept, embodiments of the present invention also provide a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the compressor oil level determination method provided in the above embodiments.

[0134] The steps executed by the aforementioned computer program during runtime will not be described in detail here, but can be found in the explanation of the compressor oil level determination method above.

[0135] In the several embodiments provided by this invention, it should be understood that the disclosed methods can also be implemented in other ways. The embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate methods according to various embodiments of the invention. In this regard, each block in a flowchart or block diagram may represent a segment or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the oil level in a compressor, characterized in that, A controller used in an air conditioner, the controller being electrically connected to an expansion valve and a compressor in the air conditioner, the expansion valve being disposed between an oil separator and a gas-liquid separator in the air conditioner, the method comprising: The oil temperature at the connection side of the expansion valve and the gas-liquid separator, and the discharge temperature of the compressor are obtained; Multiple temperature ranges are set based on the exhaust temperature; The temperature range of the oil temperature is determined. If the oil temperature is determined to be in one of the temperature ranges in a preset period, the expansion valve is controlled to operate at preset intervals until the oil temperature is determined to be in another temperature range. The opening degree of the expansion valve and the frequency of the compressor are obtained. The oil level of the compressor is determined based on the opening degree of the expansion valve and the frequency of the compressor. The plurality of temperature ranges includes a first temperature range and a second temperature range, and the step of setting the plurality of temperature ranges based on the exhaust temperature includes: Obtain the difference between the exhaust temperature and the preset temperature, and use the difference as the first temperature value; Obtain the sum of the exhaust temperature and the preset sensor error compensation value, and use the sum as the second temperature value; The temperature range in which the oil temperature is greater than the first temperature value and less than the second temperature value is set as the first temperature range; The temperature range in which the oil temperature is less than or equal to the first temperature value is set as the second temperature range.

2. The method for determining the compressor oil level according to claim 1, characterized in that, An oil temperature sensor is provided on the connection side of the expansion valve and the gas-liquid separator, and an exhaust temperature sensor is provided on the exhaust side of the compressor. The controller is electrically connected to the oil temperature sensor and the exhaust temperature sensor. The steps of obtaining the oil temperature at the connection side of the expansion valve and the gas-liquid separator, and the discharge temperature of the compressor, include: The oil temperature detected by the oil temperature sensor at the connection side of the expansion valve and the gas-liquid separator, and the exhaust temperature detected by the exhaust temperature sensor at the compressor are obtained.

3. The method for determining the compressor oil level according to claim 1, characterized in that, The step of determining the temperature range of the oil temperature, and controlling the expansion valve to operate at preset time intervals when the oil temperature is determined to be within a certain temperature range throughout a preset period, until the oil temperature is determined to be within another temperature range, and obtaining the current opening degree of the expansion valve and the compressor frequency, and determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency, includes: The temperature range of the oil temperature is determined. If the oil temperature is determined to be in the first temperature range for a preset period, the expansion valve is controlled to open to a preset degree at preset intervals until the oil temperature is determined to be in the second temperature range. The current opening degree of the expansion valve and the frequency of the compressor are then obtained. The compressor oil level is determined based on the current opening degree of the expansion valve and the compressor frequency.

4. The method for determining the compressor oil level according to claim 1, characterized in that, The step of determining the temperature range of the oil temperature, and controlling the expansion valve to operate at preset time intervals when the oil temperature is determined to be within a certain temperature range throughout a preset period, until the oil temperature is determined to be within another temperature range, obtaining the current opening degree of the expansion valve and the compressor frequency, and determining the compressor oil level based on the current opening degree of the expansion valve and the compressor frequency, further includes: The temperature range of the oil temperature is determined. If the oil temperature is determined to be in the second temperature range for a preset period, the expansion valve is controlled to open to a preset degree at preset intervals until the oil temperature is determined to be in the first temperature range. The current opening degree of the expansion valve and the frequency of the compressor are then obtained. The compressor oil level is determined based on the current opening degree of the expansion valve and the compressor frequency.

5. The method for determining the compressor oil level according to claim 1, characterized in that, The method further includes: The temperature range in which the oil temperature is greater than or equal to the second temperature value is set as the third temperature range.

6. The method for determining the compressor oil level according to claim 5, characterized in that, The method further includes: Determine the temperature range of the oil temperature. If the oil temperature is in the third temperature range, determine that the oil temperature sensor is malfunctioning.

7. An air conditioner, characterized in that, Includes multiple outdoor units and a controller, with each outdoor unit connected in parallel; Each of the outdoor units includes a compressor, a four-way valve, and a gas-liquid separator. The compressor, the four-way valve, and the gas-liquid separator are connected in sequence. An oil separator is connected in series between the compressor and the four-way valve. An expansion valve is connected in series between the oil separator and the gas-liquid separator. An oil temperature sensor is provided on the connection side between the expansion valve and the gas-liquid separator. An exhaust temperature sensor is provided on the exhaust side of the compressor. The controller is electrically connected to the expansion valve and the compressor. The controller is also electrically connected to the oil temperature sensor and the exhaust temperature sensor. The controller is used to execute the compressor oil level determination method as described in any one of claims 1-6, to obtain the oil temperature detected by the oil temperature sensor at the connection side of the expansion valve and the gas-liquid separator, and the discharge temperature detected by the discharge temperature sensor of the compressor, to set multiple temperature ranges based on the discharge temperature, to determine the temperature range in which the oil temperature is located, and, if it is determined that the oil temperature is in one of the temperature ranges in a preset period, to control the expansion valve to operate at preset intervals until it is determined that the oil temperature is in other temperature ranges, to obtain the current opening degree of the expansion valve and the frequency of the compressor, and to determine the compressor oil level based on the current opening degree of the expansion valve and the frequency of the compressor.

8. A controller, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is used to execute the computer program to implement the compressor oil level determination method as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the compressor oil level determination method as described in any one of claims 1-6.

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