Heating control method for air conditioner

Abstract

This invention relates to the field of air conditioning technology, specifically to a heating control method for an air conditioner. This application aims to solve the problems of reduced heating capacity and easy frosting of the outdoor unit in cold conditions. To this end, the air conditioner of this application includes a variable-capacity compressor and a gas supply device. The gas supply device is connected to the compressor's suction port via a gas supply pipeline, and a second throttling device is installed on the gas supply pipeline. During heating operation, the temperature of the first coil of the outdoor heat exchanger is acquired; the first coil temperature is compared with a preset temperature threshold; based on the comparison result, the operating mode of the variable-capacity compressor is determined, and gas is selectively supplied to the variable-capacity compressor. This application can effectively suppress frosting by using gas supply, while ensuring the system's heating capacity and improving system energy efficiency. The variable-capacity compressor can make the heating and defrosting processes more efficient by switching operating modes, ensuring a better user experience.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically to a heating control method for an air conditioner. Background Technology

[0002] In recent years, energy shortages and environmental pollution have become increasingly serious problems, becoming one of the main factors restricting social development. Traditional methods of providing heat through fuel combustion or electric heating have significant shortcomings in terms of energy utilization and environmental protection, and are gradually being replaced by more energy-efficient and environmentally friendly heat pump systems. Air source heat pumps are heat pump devices that use ambient air as a high-temperature (low-temperature) heat source to meet cooling (heating) needs. They have a simple structure, are easy to use, and are suitable for individual household installations, making them the main type of indoor air conditioner used in my country.

[0003] However, traditional air source heat pump systems are greatly affected by the ambient temperature. For example, in extreme climates such as severe cold, they will exhibit phenomena such as a gradual decrease in heating capacity, easy frosting of the outdoor unit, and unstable system operation, which limits the applicable scope of air source heat pump systems.

[0004] Accordingly, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0005] To address at least one of the aforementioned problems in the prior art, namely, to solve the issues of reduced heating capacity and easy frosting of the outdoor unit in cold conditions, this application provides a heating control method for an air conditioner. The air conditioner includes a variable-capacity compressor, an indoor heat exchanger, a first throttling device, and an outdoor heat exchanger, all connected via refrigerant piping. The variable-capacity compressor has two compression cylinders. The air conditioner also includes a gas injection device, which is located on the refrigerant piping between the indoor heat exchanger and the first throttling device. The gas injection device is connected to the compressor's suction port via a gas injection piping, and a second throttling device is installed on the gas injection piping.

[0006] The heating control method includes:

[0007] During heating operation, the temperature of the first coil of the outdoor heat exchanger is obtained;

[0008] Compare the temperature of the first coil with the preset temperature threshold.

[0009] Based on the comparison results, the operating mode of the variable capacity compressor is determined, and gas is selectively supplied to the variable capacity compressor.

[0010] The variable capacity compressor operates in two modes: a dual-cylinder mode and a two-stage mode. In the dual-cylinder mode, the two compression cylinders of the variable capacity compressor compress the refrigerant individually. In the two-stage mode, the two compression cylinders of the variable capacity compressor compress the refrigerant sequentially.

[0011] In the preferred embodiment of the heating control method for the aforementioned air conditioner, the step of "determining the operating mode of the variable capacity compressor based on the comparison results" further includes:

[0012] If the temperature of the first coil is less than or equal to the preset temperature threshold, then the working mode of the variable capacity compressor is determined to be dual-cylinder mode.

[0013] If the temperature of the first coil is greater than the preset temperature threshold, then the operating mode of the variable capacity compressor is determined to be two-stage mode.

[0014] In the preferred embodiment of the heating control method for the aforementioned air conditioner, the step of "selectively replenishing gas to the variable capacity compressor based on the comparison results" further includes:

[0015] If the temperature of the first coil is less than or equal to the preset temperature threshold, then gas is supplied to the variable capacity compressor.

[0016] In the preferred embodiment of the heating control method for the above-mentioned air conditioner, the step of "replenishing gas to the variable capacity compressor" further includes:

[0017] Control the second throttling device to open to a preset degree.

[0018] In a preferred embodiment of the heating control method for the aforementioned air conditioner, after the step of "controlling the second throttling device to open to a preset degree", the heating control method further includes:

[0019] The temperatures of multiple second coils of the outdoor heat exchanger are obtained, and the rate of temperature change between the subsequent second coil temperature and the previous second coil temperature is calculated.

[0020] Determine the magnitude of the temperature change rate compared to a preset change rate threshold;

[0021] Based on the comparison results, the opening degree of the second throttling device is controlled.

[0022] In the preferred embodiment of the heating control method for the above-mentioned air conditioner, the step of "controlling the opening degree of the second throttling device based on the comparison result" further includes:

[0023] If the temperature change rate is greater than or equal to the temperature change rate threshold, the second throttling device is controlled to maintain its current opening until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold.

[0024] In the preferred embodiment of the heating control method for the above-mentioned air conditioner, the step of "controlling the opening degree of the second throttling device based on the comparison result" further includes:

[0025] If the temperature change rate is less than the temperature change rate threshold, the opening of the second throttling device is increased until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold.

[0026] In the preferred embodiment of the heating control method for the above-mentioned air conditioner, the step of "controlling the opening degree of the second throttling device to increase" further includes:

[0027] The opening degree of the second throttling device is increased as follows:

[0028] B + B × (Tpn-1 / Tpn)

[0029] Wherein, B is the current opening degree of the second throttling device; Tpn-1 is the prior second coil temperature; and Tpn is the subsequent second coil temperature.

[0030] In the preferred embodiment of the heating control method for the above-mentioned air conditioner, the preset temperature threshold is determined based on the temperature range of the outdoor ambient temperature and the dew point temperature corresponding to the outdoor ambient temperature.

[0031] In the preferred embodiment of the heating control method for the aforementioned air conditioner, the step of "determining the preset temperature threshold based on the temperature range of the outdoor ambient temperature and the dew point temperature corresponding to the outdoor ambient temperature" further includes:

[0032] The preset temperature threshold is determined using the following formula:

[0033] Ty = Tes + a

[0034] Where Ty is the preset temperature threshold; Tes is the dew point temperature; and a is a correction coefficient, which is determined based on the temperature range of the outdoor ambient temperature.

[0035] The technical solution of this application, by setting up a gas injection device and a second throttling device on the gas injection pipeline, can guide part of the refrigerant back to the compressor when the temperature of the first coil of the outdoor heat exchanger is too low, i.e., when the outdoor heat exchanger is prone to frosting or has already frosted, by performing a gas injection operation on the variable capacity compressor. This reduces the refrigerant flow to the outdoor heat exchanger, suppresses frosting, and also increases the compressor's suction temperature, thereby increasing the system enthalpy, broadening the air conditioner's applicability in low-temperature environments, ensuring that the system's heating capacity does not decrease, improving system energy efficiency, and solving the problem of unstable compressor operation. By setting up a variable capacity compressor, the heating and defrosting processes can be made more efficient through the switching of the variable capacity compressor's operating mode, ensuring a better user experience. Attached Figure Description

[0036] The present application will now be described with reference to the accompanying drawings. In the drawings:

[0037] Figure 1 This is a system diagram of the heating process of the air conditioner in this application;

[0038] Figure 2 A system diagram of the air supply process for the air conditioner in this application;

[0039] Figure 3 This is a flowchart of the heating control method for the air conditioner according to this application;

[0040] Figure 4 This is a logic diagram of one possible implementation of the heating control method for the air conditioner of this application.

[0041] List of reference numerals

[0042] 1. Variable capacity compressor; 11. First compression cylinder; 12. Second compression cylinder; 13. First port; 14. Second port; 15. Third port; 16. Fourth port; 17. Exhaust port; 2. Second four-way valve; 3. Indoor heat exchanger; 41. First throttling device; 42. Second throttling device; 5. Outdoor heat exchanger; 61. Refrigerant pipeline; 62. Gas makeup pipeline; 7. Gas makeup device; 8. First four-way valve; 9. Gas-liquid separator. Detailed Implementation

[0043] Preferred embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application. For example, although the indoor heat exchanger in the drawings is described in conjunction with parallel internal and external exhaust pipes, this arrangement is not fixed and can be adjusted as needed to adapt to specific applications. For instance, the indoor heat exchanger may include only internal or external exhaust heat exchange pipes, or the internal and external exhaust pipes may be connected in series.

[0044] It should be noted that in the description of this application, terms such as "left" and "right," indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Additionally, in the description of this application, "a plurality of" refers to at least two.

[0045] Furthermore, it should be noted that, in the description of this application, 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] First refer to Figure 1 and Figure 2 The present application describes the air conditioner.

[0047] like Figure 1 and Figure 2 As shown, to address the issues of reduced heating capacity and easy frosting of the outdoor unit in cold conditions, the air conditioner of this application includes a variable capacity compressor 1, a second four-way valve 2, an indoor heat exchanger 3, a first throttling device 41, and an outdoor heat exchanger 5. The variable capacity compressor 1, the second four-way valve 2, the indoor heat exchanger 3, the first throttling device 41, and the outdoor heat exchanger 5 are sequentially connected via refrigerant piping 61 to form a heating cycle. The indoor heat exchanger 3 has an internal exhaust pipe and an external exhaust pipe, which are connected in parallel. The above connection method and heating working principle are conventional techniques in this field and will not be elaborated further in this application.

[0048] The outdoor heat exchanger 5 includes a main heat exchange tube section and an auxiliary heat exchange tube section. The main heat exchange tube section and the auxiliary heat exchange tube section are connected in parallel, and their inlets are simultaneously connected to the first throttling device 41, and their outlets are simultaneously connected to the second four-way valve 2.

[0049] The air conditioner also includes a gas supply device 7, which is preferably a flash evaporator. The flash evaporator is installed on the refrigerant line 61 between the indoor heat exchanger 3 and the first throttling device 41. The gas outlet of the flash evaporator is connected to the suction port of the variable capacity compressor 1 through a gas supply line 62, and a second throttling device 42 is installed on the gas supply line 62. Preferably, the first throttling device 41 and the second throttling device 42 are electronic expansion valves.

[0050] The variable displacement compressor 1 has two compression cylinders. Specifically, the variable displacement compressor 1 has a first compression cylinder 11 and a second compression cylinder 12 inside. The compressor 1 housing has four ports and one exhaust port 17. The first port 13 is connected to the air inlet of the first compression cylinder 11, the second port 14 is connected to the air outlet of the first compression cylinder 11, the third port 15 is connected to the air inlet of the second compression cylinder 12, the air outlet of the second compression cylinder 12 is connected to the exhaust port 17, and the fourth port 16 is connected to the exhaust port 17 through the inside of the housing.

[0051] The variable displacement compressor 1 is also equipped with a first four-way valve 8, which has four ports a, b, c, and d. Port a is connected to the fourth port 16, port b is connected to the second port 14, and port c is connected to the third port 15. A moving part is installed inside the four-way valve. When the four-way valve is energized or de-energized, the moving part moves within the four-way valve to connect or disconnect the different ports.

[0052] The four-way valve is connected to two gas-liquid separators 9, and the outlets of the two gas-liquid separators 9 are respectively connected to the two compression cylinders of the variable displacement compressor 1. One gas-liquid separator 9 has its outlet directly connected to the first port 13, while the other gas-liquid separator 9 has its outlet connected indirectly to the third port 15 via the fourth port d of the first four-way valve 8. One end of the air supply line 62 is connected to the inlet of one of the gas-liquid separators 9. Figure 1 and Figure 2 The diagram shows the connection to the inlet of the gas-liquid separator 9 on the right.

[0053] Under the above configuration, the variable displacement compressor 1 operates in two-cylinder and two-stage modes. See also... Figure 1 When the first four-way valve 8 is energized, it operates in two-stage mode. In this mode, the two compression cylinders of the variable capacity compressor 1 compress the refrigerant sequentially. Specifically, the first port a and the fourth port d of the first four-way valve 8 are separated by a moving part. The refrigerant discharged from the outdoor heat exchanger 5 passes through one of the gas-liquid separators 9 and then enters the first compression cylinder 11 through the first port 13. After being compressed by the first compression cylinder 11, it is discharged through the second port 14. Then, after passing through the second port b and the third port c of the first four-way valve 8, it enters the second compression cylinder 12 through the third port 15. After secondary compression by the second compression cylinder 12, it is discharged through the exhaust port 17.

[0054] See Figure 2When the first four-way valve 8 is de-energized, it operates in dual-cylinder mode. In this mode, the two compression cylinders of the variable-capacity compressor 1 compress the refrigerant independently. Specifically, a portion of the refrigerant discharged from the outdoor heat exchanger 5 passes through one of the gas-liquid separators 9 and enters the first compression cylinder 11 through the first port 13. After being compressed by the first compression cylinder 11, it is discharged through the second port 14, then passes through the second port b and the first port a of the first four-way valve 8 into the housing and is finally discharged through the exhaust port 17. The other portion of the refrigerant passes through the other gas-liquid separator 9 and then through the fourth port d and the third port c of the first four-way valve 8. It then enters the second compression cylinder 12 through the third port 15, is compressed by the second compression cylinder 12, and is discharged through the exhaust port 17.

[0055] During normal heating, the first throttling device 41 is open and the second throttling device 42 is closed. The variable capacity compressor 1 operates in two-stage mode. The refrigerant discharged from the variable capacity compressor 1 is discharged after two-stage compression and enters the indoor heat exchanger 3 to exchange heat with the indoor air after passing through the four-way valve. After heat exchange, the refrigerant flows out of the indoor heat exchanger 3 and flows into the first throttling device 41 after passing through the flash evaporator. After being throttled by the first throttling device 41, it enters the main heat exchange tube section and the auxiliary heat exchange tube section of the outdoor heat exchanger 5 to exchange heat with the outdoor air. Multiple heating circuits can reduce pressure drop loss. After heat exchange, the refrigerant flows out of the outdoor heat exchanger 5 and merges back to the variable capacity compressor 1 through the four-way valve, completing the system cycle.

[0056] When the coil temperature of the outdoor heat exchanger 5 is too low during the heating process, the second throttle valve is opened, and the variable capacity compressor 1 operates in dual-cylinder mode. The first compression cylinder 11 and the second compression cylinder 12 of the variable capacity compressor 1 compress the refrigerant and discharge it together to the indoor heat exchanger 3. Part of the refrigerant discharged from the indoor heat exchanger 3 continues to participate in the heating cycle through the outdoor heat exchanger 5, while the other part of the refrigerant enters the gas supply line 62 through the flash evaporator and is throttled by the second throttle valve. It then flows back to the gas supply port of the variable capacity compressor 1 along the gas supply line 62 to supply gas to the variable capacity compressor 1, reduce the refrigerant flow of the outdoor heat exchanger 5, and increase the suction temperature of the variable capacity compressor 1.

[0057] Those skilled in the art will understand that the above-described configuration of the air conditioner is merely a preferred embodiment. They can adjust the structure of the air conditioner without departing from the principles of this application, making it applicable to more specific application scenarios. For example, although the air conditioner is described in conjunction with the inclusion of a four-way valve, this implementation is not fixed. In other embodiments, those skilled in the art can selectively omit the four-way valve, making the air conditioner a heating-only unit. Furthermore, although the gas supply device 7 is described in conjunction with a flash evaporator, its form is not unique; it can also be an economizer or a gas-liquid separator, etc. Moreover, this application does not limit the specific forms of the first throttling device 41 and the second throttling device 42. The first throttling device 41 can also be a capillary tube or a thermal expansion valve, and the second throttling device 42 can also be other valve bodies with adjustable opening. For example, although the outdoor heat exchanger 5 is described in conjunction with the main heat exchange tube section and the auxiliary heat exchange tube section, the specific structural form of the outdoor heat exchanger 5 is not fixed. Those skilled in the art can substitute it, such as including only the main heat exchange tube section and omitting the auxiliary heat exchange tube section. For example, the switching between the two-cylinder mode and the two-stage mode of the variable-capacity compressor 1 can be achieved not through the first four-way valve 8, but by setting multiple valve groups and controlling the opening and closing of each valve within the valve group. For example, the specific structural form of the variable-capacity compressor 1 is not fixed. Provided that the switching between the two-cylinder mode and the two-stage mode can be achieved, those skilled in the art can adjust the structure of the variable-capacity compressor 1, such as changing the number, position, and connection relationship of the ports. For example, the gas-liquid separator 9 is not mandatory; those skilled in the art can select it according to specific needs.

[0058] The following reference Figure 3 The heating control method of this application is described below.

[0059] like Figure 3 As shown, corresponding to the aforementioned air conditioner, the heating control method of the air conditioner in this application includes:

[0060] S101. During heating operation, the temperature of the first coil of the outdoor heat exchanger is obtained. For example, the temperature of the first coil of the outdoor heat exchanger can be obtained by a temperature sensor installed on the outdoor heat exchanger. The location of the temperature sensor is not limited in this application; it can be installed on the main heat exchange tube section or on the auxiliary heat exchange tube section.

[0061] S103. Compare the temperature of the first coil with the preset temperature threshold. For example, the preset temperature threshold is pre-set. This preset temperature threshold can be the temperature at which the outdoor heat exchanger will frost under the current ambient temperature, or it can be the dew point temperature corresponding to the current ambient temperature. This threshold is determined by empirical values, formulas, or experiments, etc. The specific determination method will be described in detail below. After obtaining the temperature of the first coil, the difference or ratio between the temperature of the first coil and the preset temperature threshold is calculated to compare their magnitudes.

[0062] S105. Based on the comparison results, determine the operating mode of the variable capacity compressor and selectively replenish gas to the compressor. For example, if the temperature of the first coil is less than or equal to the preset temperature threshold, it indicates that the temperature of the outdoor heat exchanger coil is too low, which will cause frost to form on the outdoor heat exchanger. In this case, the variable capacity compressor can be controlled to operate in dual-cylinder mode, and gas replenishment can be performed to reduce the refrigerant flow to the outdoor heat exchanger, thereby suppressing frost formation. Conversely, if the temperature of the first coil is greater than the preset temperature threshold, it indicates that the temperature of the outdoor heat exchanger coil is within the normal range. In this case, there is no need to replenish gas to the compressor; the current operating state of the air conditioner can be maintained.

[0063] The technical solution of this application, by setting up a gas injection device and a second throttling device on the gas injection pipeline, can guide part of the refrigerant back to the variable capacity compressor when the temperature of the first coil of the outdoor heat exchanger is too low, i.e., when the outdoor heat exchanger is prone to frosting or has already frosted. This reduces the refrigerant flow to the outdoor heat exchanger, suppresses frosting, and also increases the suction temperature of the variable capacity compressor by injecting gas, thereby increasing the system enthalpy, broadening the applicability of the air conditioner in low-temperature environments, ensuring that the system's heating capacity does not decrease, improving system energy efficiency, and solving the problem of unstable operation of the variable capacity compressor. By setting up a variable capacity compressor, the heating and defrosting processes can be made more efficient by switching the operating mode of the variable capacity compressor, ensuring a better user experience.

[0064] The preferred technical solution of this application is described below.

[0065] In the preferred technical solution of the heating control method for the aforementioned air conditioner, the step of "determining the operating mode of the variable capacity compressor based on the comparison results" further includes: if the temperature of the first coil is less than or equal to a preset temperature threshold, the operating mode of the variable capacity compressor is determined to be a dual-cylinder mode; if the temperature of the first coil is greater than the preset temperature threshold, the operating mode of the variable capacity compressor is determined to be a two-stage mode. Specifically, when the temperature of the first coil is greater than the preset temperature threshold, the coil temperature of the outdoor heat exchanger is within the normal range. At this time, controlling the compressor to operate in two-stage mode can achieve a larger compression ratio at a lower operating frequency, thereby meeting the condensing temperature requirements and ensuring the heating effect and heating efficiency of the air conditioner. When the temperature of the first coil is less than or equal to the preset temperature threshold, it proves that the coil temperature of the outdoor heat exchanger is low, and there is a risk of frosting. At this time, the compressor operating mode is switched to dual-cylinder mode, and the frequency is lower at the same discharge volume. This makes the high pressure of the air conditioning system lower and the low pressure higher, the compression ratio of the compressor decreases, and the discharge temperature of the compressor will decrease. In addition, some refrigerant flows back to the variable capacity compressor through the gas injection pipeline, which delays frosting.

[0066] Of course, the above control method is merely a preferred option, and those skilled in the art can adjust it. For example, the control logic when the temperature of the first coil exceeds a preset temperature threshold can be selectively omitted.

[0067] In one embodiment, the step of "selectively replenishing gas to the variable-capacity compressor based on the comparison results" further includes: if the temperature of the first coil is less than or equal to a preset temperature threshold, then replenishing gas to the variable-capacity compressor. Specifically, the step of "replenishing gas to the variable-capacity compressor" further includes: controlling the second throttling device to open to a preset opening degree. Preferably, the preset opening degree is the rated opening degree of the second throttling device, which can be preset at the factory by the electronic expansion valve, or it can be adjusted by the operator according to different air conditioner models. When the temperature of the first coil is less than or equal to the preset temperature threshold, controlling the second throttling device to open to the preset opening degree allows some refrigerant to flow back to the variable-capacity compressor through the gas replenishment pipeline, reducing the refrigerant flow to the outdoor heat exchanger and suppressing frost formation.

[0068] Of course, the above control method is merely a preferred option, and those skilled in the art can adjust it as long as it can achieve gas replenishment to the variable-capacity compressor. For example, opening the second throttling device to its minimum opening degree, etc.

[0069] In one embodiment, after the step of "controlling the second throttling device to open to a preset opening degree", the heating control method further includes: acquiring multiple second coil temperatures of the outdoor heat exchanger and calculating the rate of temperature change between the subsequent second coil temperature and the previous second coil temperature; determining the magnitude of the rate of temperature change compared to a preset rate of change threshold; and controlling the opening degree of the second throttling device based on the comparison result. Specifically, if the rate of temperature change is greater than or equal to the preset rate of change threshold, the second throttling device is controlled to maintain its current opening degree until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold. If the rate of temperature change is less than the preset rate of change threshold, the opening degree of the second throttling device is controlled to increase until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold.

[0070] For example, after controlling the second throttling device to open to the rated opening, this application calculates the second coil temperature every 15 seconds, and starting from the second second coil temperature, calculates the temperature change rate between the subsequent second coil temperature and the previous second coil temperature, i.e., Tpn / Tpn-1, where Tpn is the subsequent second coil temperature and Tpn-1 is the previous second coil temperature. After calculating the temperature change rate, it is compared with a preset change rate threshold. In this application, the preset change rate threshold is taken as 1, i.e., whether Tpn / Tpn-1≥1 is true. If it is true, it proves that the coil temperature has increased or has not continued to decrease. At this time, the opening of the second throttling device has a frosting effect, and it is only necessary to maintain the current opening until the detected outdoor heat exchanger coil temperature is greater than the preset temperature threshold, and there is no risk of frosting.

[0071] Conversely, if Tpn / Tpn-1≥1 does not hold, it indicates that the outdoor coil temperature has further decreased, increasing the risk of frosting. In this case, it is necessary to further increase the opening of the second throttling device to allow more refrigerant to flow back to the variable-capacity compressor, further reducing the amount of refrigerant passing through the outdoor heat exchanger. Preferably, the step of "controlling the increase of the opening of the second throttling device" further includes: controlling the opening of the second throttling device to increase as follows:

[0072] B+B×(Tpn-1 / Tpn)(1)

[0073] Where B is the current opening degree of the second throttling device; Tpn-1 is the previous second coil temperature; and Tpn is the subsequent second coil temperature.

[0074] In other words, when adjusting the opening of the second throttling device, this application adapts the adjustment opening of the second throttling device to the current temperature change rate, thereby achieving rapid and precise adjustment of the gas supply while suppressing frost formation through dynamic gas replenishment for heating.

[0075] Of course, the above control method is only a preferred option. Those skilled in the art can adjust the above implementation method so that this application can be applied to more specific application scenarios. In other implementation methods, for example, the above-mentioned step of adjusting the second throttling device can be omitted. For example, the opening degree of the second throttling device can also be adjusted by comparing the temperature of the second coil with that of the first coil, or by the difference between the temperature of the second coil after the second coil and that of the first coil. For example, the preset rate of change threshold can be any other possible value other than 1. This application only uses 1 as an example, and this value does not represent an improper limitation of this application. For example, the specific opening degree of the second throttling device can be continuously increased, or it can be increased after each judgment. In addition to using the above formula (1) to determine the increased opening degree, it can also be determined by increasing a fixed opening degree each time, or by using a comparison table between the increased opening degree and the ratio.

[0076] In one embodiment, the preset temperature threshold is determined based on the outdoor ambient temperature. Specifically, the step of "determining the preset temperature threshold based on the outdoor ambient temperature" further includes: calculating the dew point temperature based on the outdoor ambient temperature; and determining the preset temperature threshold based on the temperature range between the dew point temperature and the outdoor ambient temperature. Preferably, the step of "determining the preset temperature threshold based on the temperature range between the dew point temperature and the outdoor ambient temperature" further includes: determining the preset temperature threshold using the following formula:

[0077] Ty = Tes + a (2)

[0078] Where Ty is the preset temperature threshold; Tes is the dew point temperature; and a is the correction coefficient, which is determined based on the temperature range of the outdoor ambient temperature.

[0079] For example, the correction factor 'a' is determined as follows: when Tao ≥ 7℃, a = 0℃; when 7 ≤ Tao < -5℃, a = 3℃; when Tao < -5℃, a = 1℃.

[0080] In one embodiment, the dew point temperature is determined by the following formula:

[0081] Tes=C×Tao-b (3)

[0082] Where Tes is the dew point temperature; C is a coefficient; Tao is the outdoor ambient temperature; and b is a constant. One approach is to determine the value of C based on the outdoor ambient temperature after release: when Tao < 0℃, C = 0.8; when Tao ≥ 0℃, C = 0.6. In another implementation, b = 6.

[0083] Of course, the above values ​​are merely illustrative examples, and those skilled in the art can adjust them based on specific application scenarios.

[0084] By determining the dew point temperature based on the outdoor ambient temperature, and further determining the preset temperature threshold based on the outdoor ambient temperature and the dew point temperature, the accuracy of judging the frosting process can be improved, and the frosting status of the outdoor heat exchanger can be accurately judged.

[0085] Of course, the methods for determining the preset temperature threshold and the dew point temperature are not unique, and those skilled in the art can adjust them. For example, they can also be determined using fixed values, reference tables, empirical formulas, etc.

[0086] The following is combined Figure 4 This paper will now describe one possible implementation process of this application.

[0087] like Figure 4 As shown, in one possible operation:

[0088] S201, during heating operation, obtain the first coil temperature Tp of the outdoor heat exchanger and the outdoor ambient temperature Tao.

[0089] S202, based on the outdoor ambient temperature Tao, the dew point temperature Tes is determined using formula (3), and then the preset temperature threshold Tes+a is determined using formula (2).

[0090] S203, determine whether Tp≤Tes+a is true? If true, execute S204; otherwise, if false, execute S209.

[0091] S204 controls the variable displacement compressor to operate in dual-cylinder mode, and the second throttling device is opened to the rated opening, and then S205 is executed.

[0092] S205, acquire the temperature of the second coil every 15s, and calculate the ratio Tpn / Tpn-1 between the temperature of the second coil after the previous one and the temperature of the second coil before the previous one.

[0093] S206, Determine if Tpn / Tpn-1≥1 is true. If true, proceed to S207; otherwise, proceed to S208.

[0094] S207, control the second throttling device to maintain the current opening until Tp > Tes + a.

[0095] S208 controls the second throttling device to increase its opening degree, wherein the increase value is determined by formula (1).

[0096] S209, control the air conditioner to maintain its current operating state.

[0097] It should be noted that although the detailed steps of the method of this application have been described in detail above, those skilled in the art can combine, split and rearrange the above steps without departing from the basic principles of this application. Such modified technical solutions do not change the basic concept of this application and therefore fall within the protection scope of this application.

[0098] Those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments in the claims of this application can be used in any combination.

[0099] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A heating control method of an air conditioner, characterized by, The air conditioner includes a variable-capacity compressor, an indoor heat exchanger, a first throttling device, and an outdoor heat exchanger, all connected via refrigerant piping. The variable-capacity compressor has two compression cylinders. The air conditioner also includes a gas injection device, which is located on the refrigerant piping between the indoor heat exchanger and the first throttling device. The gas injection device is connected to the suction port of the variable-capacity compressor via a gas injection pipe, and a second throttling device is installed on the gas injection pipe. The heating control method includes: During heating operation, the temperature of the first coil of the outdoor heat exchanger is obtained; Compare the temperature of the first coil with the preset temperature threshold. Based on the comparison results, the operating mode of the variable capacity compressor is determined, and gas is selectively supplied to the variable capacity compressor. The variable capacity compressor has two operating modes: a dual-cylinder mode and a two-stage mode. In the dual-cylinder mode, the two compression cylinders of the variable capacity compressor compress the refrigerant individually. In the two-stage mode, the two compression cylinders of the variable capacity compressor compress the refrigerant sequentially. The step of "selectively replenishing gas to the variable-capacity compressor based on the comparison results" further includes: If the temperature of the first coil is less than or equal to the preset temperature threshold, then gas is supplied to the variable capacity compressor, and the second throttling device is controlled to open to the preset opening degree. After the step of "controlling the second throttling device to open to a preset degree", the heating control method further includes: The temperatures of multiple second coils of the outdoor heat exchanger are obtained, and the rate of temperature change between the subsequent second coil temperature and the previous second coil temperature is calculated. Determine the magnitude of the temperature change rate compared to a preset change rate threshold; Based on the comparison results, the opening degree of the second throttling device is controlled; If the temperature change rate is less than the preset change rate threshold, the opening of the second throttling device is increased until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold. The opening degree of the second throttling device is increased as follows: B + B × (Tpn-1 / Tpn) Wherein, B is the current opening degree of the second throttling device; Tpn-1 is the prior second coil temperature; and Tpn is the subsequent second coil temperature.

2. The heating control method for an air conditioner according to claim 1, characterized in that, The step of "determining the operating mode of the variable capacity compressor based on the comparison results" further includes: If the temperature of the first coil is less than or equal to the preset temperature threshold, then the working mode of the variable capacity compressor is determined to be dual-cylinder mode. If the temperature of the first coil is greater than the preset temperature threshold, then the operating mode of the variable capacity compressor is determined to be two-stage mode.

3. The heating control method for an air conditioner according to claim 1, characterized in that, The step of "controlling the opening degree of the second throttling device based on the comparison results" further includes: If the temperature change rate is greater than or equal to the preset change rate threshold, the second throttling device is controlled to maintain its current opening until the coil temperature of the outdoor heat exchanger is greater than the preset temperature threshold.

4. The heating control method for an air conditioner according to claim 1, characterized in that, The preset temperature threshold is determined based on the temperature range of the outdoor ambient temperature and the dew point temperature corresponding to the outdoor ambient temperature.

5. The heating control method for an air conditioner according to claim 4, characterized in that, The step of "determining the preset temperature threshold based on the temperature range of the outdoor ambient temperature and the dew point temperature corresponding to the outdoor ambient temperature" further includes: The preset temperature threshold is determined using the following formula: Ty = Tes + a Where Ty is the preset temperature threshold; Tes is the dew point temperature; and a is a correction coefficient, which is determined based on the temperature range of the outdoor ambient temperature.

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