Method for controlling simultaneous cooling and heating air conditioner and simultaneous cooling and heating air conditioner

Abstract

This invention provides a control method and a simultaneous cooling and heating air conditioner, relating to the field of air conditioning technology. First, it implements cooling / heating functions. Then, when switching from cooling mode to heating mode, it controls the internal expansion valve of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a first preset value, at which point it opens the high-pressure solenoid valve of the corresponding pipeline. When switching from heating mode to cooling mode, it controls the opening of the low-pressure expansion valve of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the evaporating temperature Tz is lower than a second preset value, at which point it fully opens the low-pressure expansion valve of the corresponding pipeline. Finally, it transitions the internal expansion valve to normal control. After the internal heat exchange temperature Tn reaches the target, the high-pressure solenoid valve or the low-pressure expansion valve is fully opened. Because the pressure difference has been reduced to a certain extent, the piping vibration and flow noise generated during refrigerant flow are reduced, effectively solving the problem of excessive piping vibration and noise in existing technologies.

Description

Technical Field

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

[0002] In the residential air conditioning market, installation has gradually shifted from one unit per household to one unit per room, and now it's common for each household to have four or five air conditioners. Correspondingly, centered in cities, there is a growing demand for fixed-type air conditioners that can share outdoor units and reduce installation space. Additionally, in specific markets, such as small and medium-sized hotels where space for outdoor unit installation is limited, there is also a demand for fixed-type air conditioners. Among these demands, many users are further requesting fixed-type air conditioners with separate cooling and heating settings for both cooling and heating functions.

[0003] Existing technologies include simultaneous cooling and heating units, where multiple indoor units are connected to the same outdoor unit. However, the inventor discovered that switching the indoor unit's operating mode from cooling to heating requires opening the high-pressure solenoid valve on the outdoor unit, causing piping vibration and refrigerant flow noise. Similarly, switching from heating to cooling requires opening the low-pressure solenoid valve on the outdoor unit, also resulting in piping vibration and refrigerant flow noise. Summary of the Invention

[0004] The problem addressed by this invention is how to solve the piping vibration and refrigerant flow noise generated when switching modes under simultaneous heating and cooling functions.

[0005] To solve the above problems, the present invention adopts the following technical solution.

[0006] In one aspect, the present invention provides a control method for a simultaneous cooling and heating air conditioner, applicable to such air conditioners, wherein the simultaneous cooling and heating air conditioner includes an outdoor unit and multiple indoor units connected to the outdoor unit simultaneously, and the control method includes:

[0007] Set at least one of the indoor units to heating mode, open the internal expansion valve and high-pressure solenoid valve of the corresponding pipeline, and open and close the corresponding low-pressure expansion valve.

[0008] When one of the indoor units switches from cooling mode to heating mode, the opening of the internal expansion valve of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a first preset value, and then the high-pressure solenoid valve of the corresponding pipeline is opened.

[0009] Alternatively, at least one of the indoor units can be set to cooling mode, with the internal expansion valve and low-pressure expansion valve of the corresponding pipeline opened and the corresponding high-pressure solenoid valve closed.

[0010] When one of the indoor units switches from heating mode to cooling mode, the opening of the low-pressure expansion valve of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the second preset value, and then the low-pressure expansion valve of the corresponding pipeline is fully opened.

[0011] The internal expansion valve is then switched to conventional control, completing the mode switch.

[0012] The control method for a simultaneous cooling and heating air conditioner provided in this embodiment of the invention replaces the original low-pressure shut-off valve with a low-pressure expansion valve. In actual control, firstly, to achieve cooling / heating control, at least one indoor unit is set to cooling mode, the internal expansion valve and low-pressure expansion valve of the corresponding pipeline are opened, and the corresponding high-pressure solenoid valve is closed. Then, when one indoor unit switches from cooling mode to heating mode, the internal expansion valve of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a first preset value, at which point the high-pressure solenoid valve of the corresponding pipeline is opened. This ensures that the pressure difference across the high-pressure solenoid valve is not large. Alternatively, at least one indoor unit is set to heating mode, the internal expansion valve and high-pressure solenoid valve of the corresponding pipeline are opened, and the corresponding low-pressure expansion valve is closed. When one indoor unit switches from heating mode to cooling mode, the opening degree of the internal expansion valve and low-pressure expansion valve of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a second preset value, at which point the low-pressure expansion valve of the corresponding pipeline is fully opened. This also ensures that the pressure difference across the high-pressure solenoid valve is not large. Finally, the internal expansion valve is switched to conventional control, completing the mode switch. Compared to existing technologies, this embodiment of the invention fully opens the high-pressure solenoid valve or the low-pressure expansion valve after the internal heat exchange temperature Tn reaches the target. Since the pressure difference across the valve has been reduced to a certain extent, the piping vibration and flow noise generated during the refrigerant flow are smaller, effectively solving the problem of large piping vibration and noise in existing technologies.

[0013] Further, the step of controlling the internal expansion valve of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is lower than a first preset value to open the high-pressure solenoid valve of the corresponding pipeline includes:

[0014] Close the low-pressure expansion valve of the corresponding pipeline;

[0015] Set the internal expansion valve of the corresponding pipeline to the first preset opening degree;

[0016] The internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit are obtained under the mode switching state;

[0017] The high-pressure solenoid valve is opened when the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is less than 10°C.

[0018] The control method for a fixed-mode air conditioner provided in this embodiment of the invention, when switching from cooling to heating, first closes the low-pressure expansion valve on the pipe corresponding to the indoor unit requiring mode switching, and sets the internal expansion valve to a first preset opening. At this time, the refrigerant begins to flow back to other indoor units in heating mode through the internal expansion valve, thereby equalizing the pressure with other indoor units in heating mode. Under these circumstances, the internal heat exchange temperature Tn of the indoor unit in mode switching begins to rise. Finally, after the internal heat exchange temperature Tn reaches the required level, the high-pressure solenoid valve is opened. Since the internal expansion valve has already equalized the pressure of the refrigerant, the pipe vibration and flow noise generated during the refrigerant flow on both sides of the high-pressure solenoid valve are relatively small, further solving the problem of large pipe vibration and noise in the prior art.

[0019] Furthermore, after obtaining the indoor unit's internal heat exchange temperature Tn and condensing temperature Tw under the mode switching state, the control method further includes:

[0020] Obtain the heat exchange temperature Tq of the indoor unit under other heating modes;

[0021] When the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate and / or the heat exchange temperature Tq of the indoor unit is lower than the preset temperature in other heating modes, the second preset opening degree of the internal expansion valve is reduced.

[0022] The air conditioning control method for simultaneous heating and cooling provided in this invention addresses the issue that when the rate of increase in the internal heat exchange temperature Tn exceeds the preset temperature rise rate, the refrigerant flow velocity increases, potentially causing refrigerant flow noise. Therefore, the opening of the internal expansion valve can be reduced to decrease the refrigerant flow velocity, preventing vibration or refrigerant flow noise during the control process. Furthermore, when the refrigerant is undergoing pressure equalization, the condensing pressure of the indoor unit in heating mode decreases, potentially leading to a drop in outlet air temperature. Therefore, the opening of the internal expansion valve can be reduced to prevent the heating function of the indoor unit in heating mode from being affected.

[0023] Furthermore, the first preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve; the second preset opening degree is 1 / 500 to 1 / 200 of the maximum opening degree of the internal expansion valve.

[0024] The control method for a simultaneous cooling and heating air conditioner provided in this embodiment of the invention can effectively ensure that the refrigerant is evenly pressurized through the internal expansion valve to reduce the pressure difference by limiting the initial opening and adjustment opening of the internal expansion valve. At the same time, it can avoid noise generated during the pressure equalization process due to excessive initial opening, and also avoid excessive impact on the refrigerant flow when adjusting the opening of the internal expansion valve. This ensures the reliable operation of the air conditioner as a whole during the pressure equalization process and improves user comfort.

[0025] Furthermore, the preset temperature rise rate is 0.5℃ / s; the preset temperature is 46℃.

[0026] The air conditioning control method for simultaneous heating and cooling provided in this invention can accurately define the noise threshold during the pressure equalization process by reasonably limiting the preset temperature rise rate. This avoids noise affecting the user experience while ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible. Simultaneously, by reasonably defining the preset temperature, it can accurately prevent the pressure equalization process from affecting other normally operating heating indoor units, while also ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible.

[0027] Furthermore, after the step of opening the internal expansion valve of the corresponding pipeline to the first preset opening degree, the control method further includes:

[0028] The indoor unit's fan is in the stop mode switching state.

[0029] The air conditioning control method for simultaneous heating and cooling provided in this embodiment of the invention stops the corresponding fan after the internal expansion valve is opened, which can avoid unnecessary airflow at different temperatures during mode switching and improve the user experience.

[0030] Further, the step of controlling the opening degree of the internal expansion valve and the low-pressure expansion valve of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the second preset value, and then fully opening the low-pressure expansion valve of the corresponding pipeline, includes:

[0031] Close the high-pressure solenoid valve and the internal expansion valve of the corresponding pipeline;

[0032] Set the internal expansion valve of the corresponding pipeline to the third preset opening degree;

[0033] The low-pressure expansion valve of the corresponding pipeline is gradually opened according to the preset opening rate;

[0034] The internal heat exchange temperature Tn and evaporation temperature Tz of the indoor unit are obtained under the mode switching state;

[0035] The low-pressure expansion valve is fully opened after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10°C.

[0036] The control method for a simultaneous heating and cooling air conditioner provided in this invention involves first closing the high-pressure solenoid valve and the internal expansion valve when switching from heating to cooling control, completely cutting off the flow pipeline. Then, the internal expansion valve is set to a third preset opening degree. In this state, the low-pressure expansion valve is gradually opened at the preset opening rate, allowing refrigerant to flow into the compressor's suction side through the low-pressure expansion valve, thus reducing the pressure. The low-pressure expansion valve can be fully opened once the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10°C. Because the low-pressure expansion valve opens gradually, rather than in one step, the refrigerant flow rate can be effectively controlled, preventing a rapid influx of refrigerant into the compressor's suction side, thereby further suppressing vibration and refrigerant flow noise.

[0037] Furthermore, after the step of gradually opening the low-pressure expansion valve of the corresponding pipeline according to a preset opening rate, the control method further includes:

[0038] When the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, the current opening degree of the low-pressure expansion valve is maintained for a preset time.

[0039] The control method for a simultaneous heating and cooling air conditioner provided in this embodiment of the invention indicates that the low-pressure expansion valve is opening too quickly when the internal heat exchange temperature Tn drops too rapidly, resulting in excessive refrigerant flow speed. This may cause refrigerant flow noise or vibration problems. Therefore, the rate of decrease of the internal heat exchange temperature Tn can be monitored. When it drops too quickly, the current opening of the low-pressure expansion valve is maintained for a certain period of time to slow down the refrigerant flow speed and avoid refrigerant flow noise or vibration problems.

[0040] Furthermore, the preset temperature drop rate is 0.5℃ / s, and the preset time is 5s.

[0041] The air conditioning control method for simultaneous heating and cooling provided in this embodiment of the invention can precisely control the refrigerant flow speed by limiting the preset temperature drop rate and preset time, further slowing down the refrigerant flow speed and avoiding refrigerant flow noise or vibration problems.

[0042] Furthermore, the third preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve, and the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the low-pressure expansion valve per second.

[0043] The control method for a simultaneous heating and cooling air conditioner provided in this embodiment of the invention limits the third preset opening degree and the preset opening rate. On the one hand, it can avoid the refrigerant from being uncontrolled due to excessive internal expansion opening. On the other hand, it can reasonably limit the opening speed of the low-pressure expansion valve to avoid refrigerant flow noise or vibration problems caused by excessive opening speed.

[0044] In another aspect, embodiments of the present invention provide a simultaneous cooling and heating air conditioner, applicable to the aforementioned simultaneous cooling and heating air conditioner, the simultaneous cooling and heating air conditioner comprising:

[0045] Multiple indoor units;

[0046] The outdoor unit includes an outdoor heat exchanger, a compression circulation pipe assembly, a high-pressure gas collection pipe, a low-pressure gas collection pipe, and a liquid distributor. The liquid distributor is connected to multiple indoor units via multiple liquid distribution pipes. The outdoor heat exchanger is connected to the liquid distributor via a pipe. The compression circulation pipe assembly is connected to the outdoor heat exchanger via a pipe. The high-pressure gas collection pipe is connected to the compression circulation pipe assembly via a pipe and is also connected to multiple indoor units via multiple high-pressure gas distribution pipes. The low-pressure gas collection pipe is connected to the compression circulation pipe assembly via a pipe and is also connected to multiple indoor units via multiple low-pressure gas distribution pipes.

[0047] The compression circulation pipe assembly is used to compress the refrigerant and adjust the refrigerant flow direction. Each liquid distribution pipe is equipped with an internal expansion valve, and each high-pressure gas distribution pipe is equipped with a high-pressure solenoid valve. The high-pressure solenoid valve is used to open in the heating state so that the refrigerant flows from the high-pressure gas collector to the corresponding indoor unit. Each low-pressure gas distribution pipe is equipped with a low-pressure expansion valve, which is used to open in the cooling state so that the refrigerant flows from the corresponding indoor unit to the low-pressure gas collector. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of an existing air conditioner that switches from cooling to heating while simultaneously providing both cooling and heating.

[0049] Figure 2 This is a schematic diagram of an existing air conditioner that switches from heating to cooling while simultaneously providing both heating and cooling.

[0050] Figure 3 This is a schematic diagram of the structure of an air conditioner that provides simultaneous heating and cooling according to an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram illustrating the steps of a simultaneous heating and cooling air conditioner control method provided in an embodiment of the present invention.

[0052] Explanation of reference numerals in the attached figures:

[0053] 100 - Simultaneous heating and cooling air conditioner; 110 - Outdoor unit; 111 - Outdoor heat exchanger; 112 - Compression circulation pipe assembly; 113 - High-pressure gas collection pipe; 114 - Low-pressure gas collection pipe; 115 - Liquid distributor; 116 - Liquid distributor pipe; 117 - High-pressure gas distribution pipe; 118 - Low-pressure gas distribution pipe; 120 - Indoor unit; 130 - Internal expansion valve; 140 - High-pressure solenoid valve; 150 - Low-pressure expansion valve. Detailed Implementation

[0054] As disclosed in the background section, existing technologies for simultaneous cooling and heating units utilize conventional control methods, as disclosed in patent CN202211160483.2. However, in such simultaneous cooling and heating units, when the indoor unit switches from cooling to heating mode, the high-pressure solenoid valve of the outdoor unit needs to be opened, which causes piping vibration and refrigerant flow noise. Similarly, when switching from heating to cooling, opening the low-pressure solenoid valve of the outdoor unit also causes piping vibration and refrigerant flow noise.

[0055] The inventors discovered that the cause of piping vibration and refrigerant flow noise is the refrigerant pressure difference. This occurs when switching from cooling to heating. Figure 1 As shown, the section of the indoor unit in low-pressure mode is connected to the high-pressure circuit (the compressor's exhaust side), and the pressure difference between them causes a rapid refrigerant flow. On the other hand, when switching from heating to cooling, as... Figure 2 As shown, the part of the indoor unit that is in a high-pressure state is connected to the low-pressure circuit (the suction side of the compressor), and the pressure difference between them causes a rapid flow of refrigerant.

[0056] To address the aforementioned problems, this invention provides a novel control method and a simultaneous cooling and heating air conditioner. To make the above-mentioned objectives, features, and advantages of this invention more apparent and understandable, specific embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0057] First Embodiment

[0058] See Figure 3 and Figure 4 This embodiment provides a control method for a simultaneous cooling and heating air conditioner 100, which is applicable to the simultaneous cooling and heating air conditioner 100. Through this control method, the problems of piping vibration and refrigerant flow noise generated during the switching of the simultaneous cooling and heating mode can be solved, thereby improving the user experience.

[0059] This embodiment also provides a simultaneous cooling and heating air conditioner 100, which includes an outdoor unit 110 and multiple indoor units 120 connected to the outdoor unit 110. The outdoor unit 110 includes an outdoor heat exchanger 111, a compression circulation pipe assembly 112, a high-pressure gas collection pipe 113, a low-pressure gas collection pipe 114, and a distributor 115. The distributor 115 is connected to the multiple indoor units 120 through multiple distributor pipes 116. The outdoor heat exchanger 111 is connected to the distributor 115 through a pipe. The compression circulation pipe assembly 112 is connected to the outdoor heat exchanger 111 through a pipe. The high-pressure gas collection pipe 113 is connected to the compression circulation pipe assembly 112 through a pipe and is connected to the multiple indoor units 120 through multiple high-pressure gas distribution pipes 117. The low-pressure gas collection pipe 114 is connected to the indoor units 120 through multiple high-pressure gas distribution pipes 117. Gas pipe 114 is connected to compression circulation pipe assembly 112 via a pipeline, and is connected to multiple indoor units 120 via multiple low-pressure gas distribution pipes 118 respectively. Among them, compression circulation pipe assembly 112 includes a compressor and a four-way valve connected by a pipeline, which are used to compress refrigerant and adjust the refrigerant flow direction. Each liquid distribution pipe 116 is equipped with an internal expansion valve 130, and each high-pressure gas distribution pipe 117 is equipped with a high-pressure solenoid valve 140. The high-pressure solenoid valve 140 is used to open in the heating state so that the refrigerant flows from the high-pressure gas collector to the corresponding indoor unit 120. Each low-pressure gas distribution pipe 118 is equipped with a low-pressure expansion valve 150. The low-pressure expansion valve 150 is used to open in the cooling state so that the refrigerant flows from the corresponding indoor unit 120 to the low-pressure gas collector 114.

[0060] The control method for the simultaneous cooling and heating air conditioner 100 provided in this embodiment includes the following steps:

[0061] S1: Set at least one indoor unit 120 to cooling mode, open the internal expansion valve 130 and low-pressure expansion valve 150 of the corresponding pipeline, and close the corresponding high-pressure solenoid valve 140.

[0062] S2: Set at least one indoor unit 120 to heating mode, open the internal expansion valve 130 and high-pressure solenoid valve 140 of the corresponding pipeline, and open and close the corresponding low-pressure expansion valve 150.

[0063] Steps S1 and S2 can be performed either one, depending on the actual heating / cooling needs. When performing step S1, all or part of the indoor unit 120 can be set to heating mode, and when performing step S2, all or part of the indoor unit can be set to cooling mode.

[0064] After setting at least one indoor unit 120 to cooling mode, when one of the indoor units 120 switches from cooling mode to heating mode, step S3 is executed: control the opening of the internal expansion valve 130 of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than the first preset value, and then open the high-pressure solenoid valve 140 of the corresponding pipeline.

[0065] After setting at least one indoor unit 120 to heating mode, when one of the indoor units 120 switches from heating mode to cooling mode, step S4 is executed: control the opening of the low-pressure expansion valve 150 of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the second preset value, and then fully open the low-pressure expansion valve 150 of the corresponding pipeline.

[0066] S5: Transition the internal expansion valve 130 to normal control, completing the mode switch.

[0067] It should be noted that, according to the inventors' research, noise caused by piping vibration and rapid refrigerant flow is mainly due to excessive pressure difference during switching, typically exceeding 0.5 MPa. In this embodiment, by controlling the internal expansion valve 130 or the low-pressure expansion valve 150, the pressure difference during circuit switching can be controlled below 0.5 MPa. The temperature and pressure used in this embodiment are those used with R32 and R410A refrigerants. This control method is also applicable to other refrigerants, but the pressure and temperature will vary.

[0068] In this embodiment, the original low-pressure shut-off valve is replaced with a low-pressure expansion valve 150. In actual control, cooling / heating control is first implemented, at least one indoor unit 120 is set to cooling mode, the internal expansion valve 130 and low-pressure expansion valve 150 of the corresponding pipeline are opened and the corresponding high-pressure solenoid valve 140 is closed. Then, when one of the indoor units 120 switches from cooling mode to heating mode, the internal expansion valve 130 of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a first preset value, at which point the high-pressure solenoid valve 140 of the corresponding pipeline is opened. This ensures that the pressure difference across the high-pressure solenoid valve 140 is not significant. At least one indoor unit 120 is set to heating mode, and the internal expansion valve 130 and high-pressure solenoid valve 140 of the corresponding pipeline are opened, while the corresponding low-pressure expansion valve 150 is closed. When one of the indoor units 120 switches from heating mode to cooling mode, the opening degree of the internal expansion valve 130 and low-pressure expansion valve 150 of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the evaporating temperature Tz is lower than a second preset value, at which point the low-pressure expansion valve 150 of the corresponding pipeline is fully opened. This ensures that the pressure difference across the high-pressure solenoid valve 140 is not significant. Finally, the internal expansion valve 130 is switched to normal control, completing the mode switching. After the internal heat exchange temperature Tn reaches the target, the high-pressure solenoid valve 140 or the low-pressure expansion valve 150 is fully opened. Since the pressure difference on both sides of the valve has been reduced to a certain extent, the pipe vibration and flow noise generated during the refrigerant flow process are small, which effectively solves the problem of large pipe vibration and noise in the existing technology.

[0069] In this embodiment, when switching the indoor unit 120 from cooling mode to heating mode and performing step S3, the specific steps may include:

[0070] S31: Close the low-pressure expansion valve 150 of the corresponding pipeline.

[0071] Specifically, the low-pressure expansion valve 150 can be closed first, so that the refrigerant stops flowing in the refrigeration circuit and stops refrigeration.

[0072] S32: Set the internal expansion valve 130 of the corresponding pipeline to the first preset opening degree.

[0073] Specifically, the first preset opening degree can be 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve 130. Preferably, the maximum opening degree of the internal expansion valve 130 can be 500 pls, so the internal expansion valve 130 can be opened to 120 pls.

[0074] S33: The fan of indoor unit 120 in the stop mode switching state.

[0075] Specifically, stopping the corresponding fan after opening the internal expansion valve 130 can prevent unnecessary airflow at high temperatures during mode switching, thus improving the user experience.

[0076] S34: Obtain the internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit 120 under the mode switching state.

[0077] Specifically, the internal heat exchange temperature Tn refers to the temperature of the heat exchanger of the indoor unit 120 when the operating mode is switched, i.e. Figure 3 The temperature of the heat exchanger at point A can be monitored using a temperature sensor. Without a high-pressure sensor, the condensing temperature Tw is the temperature of the outdoor heat exchanger 111 of the outdoor unit 110, i.e. Figure 3 The temperature of the heat exchanger at point B can be monitored by a temperature sensor. This condensing temperature Tw is the same as the average temperature of the heat exchanger in the indoor unit 120 during heating operation. However, when a high-pressure sensor is installed, the condensing temperature Tw is the high-pressure saturation temperature measured by the high-pressure sensor.

[0078] S35: Obtain the heat exchange temperature Tq of indoor unit 120 under other heating modes.

[0079] Specifically, the heat exchange temperature Tq of indoor unit 120 in heating mode refers to the temperature of the heat exchanger of indoor unit 120 in other heating modes, i.e. Figure 3 The temperature of the heat exchanger at point C can be detected by a temperature sensor, and this temperature can characterize the heating performance of the indoor unit 120 in other heating modes.

[0080] When the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate, step S36 is executed: reduce the second preset opening degree of the internal expansion valve 130.

[0081] Alternatively, when the heat exchange temperature Tq of the indoor unit 120 in other heating modes is lower than the preset temperature, step S36 is executed: reduce the second preset opening degree of the internal expansion valve 130.

[0082] Of course, when the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate and the heat exchange temperature Tq of the indoor unit 120 in other heating modes is lower than the preset temperature, step S36 is also executed.

[0083] Specifically, when the indoor unit 120 is pressurized to a high pressure, the refrigerant flow velocity increases, which may cause refrigerant flow noise. Simultaneously, the condensing pressure of the indoor unit 120 during heating operation decreases, potentially leading to a drop in outlet air temperature. The preset temperature rise rate can be 0.5℃ / second, the preset temperature can be 46℃, and the second preset opening is 1 / 500-1 / 200 of the maximum opening of the internal expansion valve 130; preferably, the second preset opening can be 5pls. Step S36 needs to be executed when any of the following conditions are met:

[0084] 1. When the internal heat exchange temperature rises at a rate greater than 0.5℃ / second, the refrigerant flows rapidly, reaching a point where the sound of the refrigerant flowing can be heard indoors.

[0085] 2. The heat exchange temperature Tq of the indoor heating unit 120 is below 46℃.

[0086] It should be noted that in this embodiment, when the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate, the refrigerant flow velocity will increase, which may cause refrigerant flow noise. Therefore, the opening of the internal expansion valve 130 can be reduced to decrease the refrigerant flow velocity and avoid vibration or refrigerant flow noise during the adjustment process. Furthermore, when the refrigerant is equalized, the condensing pressure of the indoor unit 120 in heating mode will decrease, which may lead to a decrease in the outlet air temperature. Therefore, the opening of the internal expansion valve 130 can be reduced to avoid affecting the heating function of the indoor unit 120 in heating mode.

[0087] S37: Open the high-pressure solenoid valve 140 when the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is less than 10℃.

[0088] Specifically, the difference between the internal heat exchange temperature Tn and the condensation temperature Tw can characterize the pressure difference across the high-pressure solenoid valve 140. Typically, when the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is less than 10°C, it can characterize that the pressure difference across the two sides is less than 0.5 MPa.

[0089] When switching from cooling to heating, the low-pressure expansion valve 150 on the pipe corresponding to the indoor unit 120 that needs to switch modes is first closed, and the internal expansion valve 130 is set to the first preset opening. At this time, the refrigerant begins to flow back to the other indoor units 120 in heating mode through the internal expansion valve 130, thereby equalizing the pressure with the other indoor units 120 in heating mode. Under these circumstances, the internal heat exchange temperature Tn of the indoor unit 120 that is switching modes begins to rise. Finally, after the internal heat exchange temperature Tn reaches the required level, the high-pressure solenoid valve 140 is opened. Since the internal expansion valve 130 has already equalized the pressure of the refrigerant, the pipe vibration and flow noise generated during the refrigerant flow on both sides of the high-pressure solenoid valve 140 are small, further solving the problem of large pipe vibration and noise in the prior art.

[0090] In this embodiment, the first preset opening is 1 / 5 to 2 / 5 of the maximum opening of the internal expansion valve 130, preferably 120 pls; the second preset opening is 1 / 500 to 1 / 200 of the maximum opening of the internal expansion valve 130, preferably 5 pls. By limiting the initial opening and adjustment opening of the internal expansion valve 130, it is possible to effectively ensure that the refrigerant is evenly pressurized through the internal expansion valve 130 to reduce the pressure difference, while avoiding excessive noise during the pressure equalization process caused by an excessively large initial opening. At the same time, it is also possible to avoid excessive impact on the refrigerant flow when adjusting the opening of the internal expansion valve 130, ensuring the reliable operation of the overall air conditioner during the pressure equalization process and improving user comfort.

[0091] In this embodiment, the preset temperature rise rate is 0.5℃ / s; the preset temperature is 46℃. By reasonably limiting the preset temperature rise rate, the noise threshold of the pressure equalization process can be accurately defined, thus avoiding noise that could affect the user experience while ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible. Simultaneously, by reasonably defining the preset temperature, the pressure equalization process can be accurately prevented from affecting other normally operating heating indoor units 120, while also ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible.

[0092] When switching the indoor unit 120 from heating mode to cooling mode and performing step S4, the specific steps may include:

[0093] S41: Close the high-pressure solenoid valve 140 and the internal expansion valve 130 of the corresponding pipeline.

[0094] Specifically, when switching from heating mode to cooling mode, the high-pressure solenoid valve 140 is first closed, and the internal expansion valve 130 of the corresponding pipeline is completely closed so that the refrigerant is temporarily stopped.

[0095] S42: Set the internal expansion valve 130 of the corresponding pipeline to the third preset opening degree.

[0096] Specifically, the indoor fan can be maintained at the speed before the change of operating mode, and the internal expansion valve 130 corresponding to the indoor unit 120 in the mode switching state can be set to a third preset opening degree. The third preset opening degree can be 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve 130. Preferably, the internal expansion valve 130 can be set to an opening degree of 120pls.

[0097] S43: Gradually open the low-pressure expansion valve 150 of the corresponding pipeline according to the preset opening rate.

[0098] Specifically, the preset opening rate can be 1 / 500 to 1 / 200 of the maximum opening of the low-pressure expansion valve 150. The maximum opening of the low-pressure expansion valve 150 can be 500 pls, and preferably the low-pressure expansion valve 150 can be gradually opened at a speed of 2 pls / s.

[0099] S44: Obtain the internal heat exchange temperature Tn and evaporation temperature Tz of the indoor unit 120 under the mode switching state.

[0100] Specifically, the internal heat exchange temperature Tn is the heat exchanger temperature of the indoor unit 120 during the operation mode change, i.e. Figure 3 The temperature at point A, without a high-pressure sensor, is the evaporation temperature Tz, which is the temperature of the outdoor heat exchanger 111 of the outdoor unit 110. Figure 3 The temperature of the heat exchanger at point B can be monitored by a temperature sensor. This evaporation temperature Tz is the same as the average temperature of the heat exchanger in the indoor unit 120 during cooling operation. However, when a high-pressure sensor is installed, the evaporation temperature Tz is the low-pressure saturation temperature measured by the high-pressure sensor.

[0101] S45: When the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, maintain the current opening of the low-pressure expansion valve 150 for a preset time.

[0102] Specifically, the preset temperature drop rate can be 0.5℃ / s. When the low-pressure expansion valve 150 opens too quickly, a problem will occur where refrigerant flows rapidly into the compressor suction side, generating flow noise. Therefore, if the temperature drop rate of the heat exchanger is fast enough that the sound of refrigerant flow can be heard indoors, the current opening can be maintained for 5 seconds.

[0103] It should be noted that when the internal heat exchange temperature Tn drops too quickly, it indicates that the low-pressure expansion valve 150 is opening too fast, resulting in excessive refrigerant flow speed. This may cause refrigerant flow noise or vibration problems. Therefore, the rate of decrease of the internal heat exchange temperature Tn can be monitored. If it drops too quickly, the current opening of the low-pressure expansion valve 150 should be maintained for a certain period of time to slow down the refrigerant flow speed and avoid refrigerant flow noise or vibration problems.

[0104] S46: Fully open the low-pressure expansion valve 150 after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10°C.

[0105] Specifically, if the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10℃, it indicates that the pressure difference on both sides of the low-pressure expansion valve 150 is less than 0.5MPa. At this time, the low-pressure expansion valve 150 can be fully opened without causing vibration or flow noise.

[0106] It should be noted that when switching from heating to actual cooling control, the high-pressure solenoid valve 140 and the internal expansion valve 130 are first closed to completely cut off the flow pipe. Then, the internal expansion valve 130 is set to the third preset opening degree. In this case, the low-pressure expansion valve 150 is gradually opened according to the preset opening rate, allowing the refrigerant to flow into the compressor suction side through the low-pressure expansion valve 150, thereby reducing the pressure. The low-pressure expansion valve 150 can be fully opened once the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10℃. Because the opening process of the low-pressure expansion valve 150 is gradual, rather than a one-step process, the flow rate of the refrigerant can be effectively controlled, thus preventing the refrigerant from flowing rapidly into the compressor suction side, thereby further suppressing vibration and refrigerant flow noise.

[0107] In this embodiment, the preset temperature drop rate is 0.5℃ / s, and the preset time is 5s. By limiting the preset temperature drop rate and preset time, the refrigerant flow speed can be precisely controlled, further slowing down the refrigerant flow speed and avoiding refrigerant flow noise or vibration problems.

[0108] In this embodiment, the third preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve 130, preferably 120 pls; the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the low-pressure expansion valve 150 per second, preferably 2 pls / s. By limiting the third preset opening degree and the preset opening rate, on the one hand, it can avoid the refrigerant from becoming uncontrolled due to excessive internal expansion opening, and on the other hand, it can reasonably limit the opening speed of the low-pressure expansion valve 150 to avoid refrigerant flow noise or vibration problems caused by excessive opening speed.

[0109] In summary, the control method and the simultaneous cooling and heating air conditioner 100 provided in this embodiment change the original low-pressure shut-off valve to a low-pressure expansion valve 150. In actual control, cooling / heating control is first realized by setting at least one indoor unit 120 to cooling mode, opening the corresponding pipe's internal expansion valve 130 and low-pressure expansion valve 150 and closing the corresponding high-pressure solenoid valve 140. Then, when one of the indoor units 120 switches from cooling mode to heating mode, the internal expansion valve 130 of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a first preset value, at which point the high-pressure solenoid valve 140 of the corresponding pipeline is opened. This ensures that the pressure difference across the high-pressure solenoid valve 140 is not significant. Alternatively, at least one indoor unit 120 is set to heating mode, and the internal expansion valve 130 and high-pressure solenoid valve 140 of the corresponding pipeline are opened, while the corresponding low-pressure expansion valve 150 is closed. When one of the indoor units 120 switches from heating mode to cooling mode, the opening degree of the internal expansion valve 130 and low-pressure expansion valve 150 of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the evaporating temperature Tz is lower than a second preset value, at which point the low-pressure expansion valve 150 of the corresponding pipeline is fully opened. This ensures that the pressure difference across the high-pressure solenoid valve 140 is not significant. Finally, the internal expansion valve 130 is transitioned to normal control, completing the mode switching. Once the internal heat exchange temperature Tn reaches the target, the high-pressure solenoid valve 140 or the low-pressure expansion valve 150 is fully opened. Because the pressure difference across the valves has decreased to a certain level, the piping vibration and flow noise generated during refrigerant flow are reduced, effectively solving the problem of excessive piping vibration and noise in existing technologies. Simultaneously, during mode switching, the refrigerant flow rate is effectively controlled by adjusting the valves, avoiding noise issues during mode switching.

[0110] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A control method for a simultaneous cooling and heating air conditioner, applicable to such an air conditioner, the simultaneous cooling and heating air conditioner comprising an outdoor unit (110) and multiple indoor units (120) simultaneously connected to the outdoor unit (110), characterized in that, The control method includes: Set at least one of the indoor units (120) to cooling mode, open the internal expansion valve (130) and low-pressure expansion valve (150) of the corresponding pipeline and close the corresponding high-pressure solenoid valve (140). When one of the indoor units (120) switches from cooling mode to heating mode, the opening of the internal expansion valve (130) of the corresponding pipeline is controlled until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than the first preset value, and then the high pressure solenoid valve (140) of the corresponding pipeline is opened. Alternatively, at least one of the indoor units (120) can be set to heating mode, and the internal expansion valve (130) and high-pressure solenoid valve (140) of the corresponding pipeline can be opened and closed, respectively. When one of the indoor units (120) switches from heating mode to cooling mode, the opening degree of the low-pressure expansion valve (150) of the corresponding pipeline can be controlled until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the second preset value, after which the low-pressure expansion valve (150) of the corresponding pipeline is fully opened. The internal expansion valve (130) is switched to normal control to complete the mode switching; The step of controlling the opening of the internal expansion valve (130) of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is lower than a first preset value, and then opening the high-pressure solenoid valve (140) of the corresponding pipeline, includes: Close the low-pressure expansion valve (150) of the corresponding pipeline. Set the internal expansion valve (130) of the corresponding pipeline to the first preset opening degree; The internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit (120) under the mode switching state are obtained; The high-pressure solenoid valve (140) is opened when the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is less than 10°C. The step of controlling the opening degree of the low-pressure expansion valve (150) of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a second preset value and then fully opening the low-pressure expansion valve (150) of the corresponding pipeline includes: Close the high-pressure solenoid valve (140) and the internal expansion valve (130) of the corresponding pipeline. Set the internal expansion valve (130) of the corresponding pipeline to the third preset opening degree; The low-pressure expansion valve (150) of the corresponding pipeline is gradually opened according to the preset opening rate. The internal heat exchange temperature Tn and evaporation temperature Tz of the indoor unit (120) under the mode switching state are obtained; The low-pressure expansion valve (150) is fully opened after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is less than 10°C.

2. The control method for a simultaneous cooling and heating air conditioner according to claim 1, characterized in that, After obtaining the internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit (120) under the mode switching state, the control method further includes: Obtain the heat exchange temperature Tq of the indoor unit (120) under other heating modes; When the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate and / or the heat exchange temperature Tq of the indoor unit (120) in other heating modes is lower than the preset temperature, the internal expansion valve (130) of the indoor unit in the cooling mode is adjusted to the second preset opening degree.

3. The control method for a simultaneous cooling and heating air conditioner according to claim 2, characterized in that, The first preset opening is 1 / 5 to 2 / 5 of the maximum opening of the internal expansion valve (130); the second preset opening is 1 / 500 to 1 / 200 of the maximum opening of the internal expansion valve (130).

4. The control method for a simultaneous cooling and heating air conditioner according to claim 2, characterized in that, The preset temperature rise rate is 0.5℃ / s; the preset temperature is 46℃.

5. The control method for a simultaneous cooling and heating air conditioner according to claim 1, characterized in that, After opening the internal expansion valve (130) of the corresponding pipeline to the first preset opening degree, the control method further includes: The fan of the indoor unit (120) in the stop mode switching state.

6. The control method for a simultaneous cooling and heating air conditioner according to claim 5, characterized in that, After the step of gradually opening the low-pressure expansion valve (150) of the corresponding pipeline according to the preset opening rate, the control method further includes: When the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, the current opening of the low-pressure expansion valve (150) is maintained for a preset time.

7. The control method for a simultaneous cooling and heating air conditioner according to claim 6, characterized in that, The preset temperature drop rate is 0.5℃ / s, and the preset time is 5s.

8. The control method for a simultaneous cooling and heating air conditioner according to claim 5, characterized in that, The third preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the internal expansion valve (130), and the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the low-pressure expansion valve (150) per second.

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