A control method for a simultaneous cooling and heating air conditioner and a 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. In actual control, the cooling / heating function is first implemented. Then, when switching from heating mode to cooling mode, the corresponding bypass expansion valve is opened until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value, at which point the low-pressure solenoid valve is opened and the bypass expansion valve is closed. Alternatively, when switching from cooling mode to heating mode, the corresponding liquid distribution expansion valve is opened first until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a second preset value, at which point the corresponding high-pressure solenoid valve is opened. Finally, the liquid distribution expansion valve is transitioned to conventional control. Opening the high-pressure or low-pressure solenoid valve only after the internal heat exchange temperature Tn reaches the target value results in less piping vibration and flow noise during refrigerant flow, effectively solving the problem of excessive piping vibration and noise.

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] At least one of the indoor units is set to heating mode, the liquid expansion valve and high-pressure solenoid valve of the corresponding pipeline are opened, and the corresponding low-pressure solenoid valve and bypass expansion valve are closed, wherein the bypass expansion valve and the low-pressure solenoid valve are connected in parallel through a bypass pipeline.

[0008] When one of the indoor units switches from heating mode to cooling mode, the corresponding bypass expansion valve is opened until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value. Then, the low-pressure solenoid valve of the corresponding pipeline is opened and the corresponding bypass expansion valve is closed.

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

[0010] When one of the indoor units switches from cooling mode to heating mode, the liquid expansion valve of the corresponding pipeline is opened until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than the second preset value, and then the high-pressure solenoid valve of the corresponding pipeline is opened.

[0011] The liquid-dispensing expansion valve is switched to conventional control to complete the mode switching.

[0012] The control method for a simultaneous cooling and heating air conditioner provided in this invention adds bypass pipes to both ends of the original low-pressure solenoid valve and installs a bypass expansion valve on the bypass pipes. In actual control, cooling / heating control is first implemented by setting at least one indoor unit to heating mode. The corresponding liquid-dispensing expansion valve and high-pressure solenoid valve are opened, while the corresponding low-pressure solenoid valve and bypass expansion valve are closed. Then, when one of the indoor units switches from heating mode to cooling mode, the corresponding bypass expansion valve is opened, refrigerant flows, and the internal heat exchange temperature Tn decreases until the internal heat exchange temperature... When the difference between the temperature Tn and the evaporation temperature Tz falls below a first preset value, the corresponding low-pressure solenoid valve opens and the corresponding bypass expansion valve closes; alternatively, at least one indoor unit is set to cooling mode, the corresponding pipe's liquid distribution expansion valve and low-pressure solenoid valve open, and the corresponding high-pressure solenoid valve and bypass expansion valve close. When one indoor unit switches from cooling mode to heating mode, the corresponding pipe's liquid distribution expansion valve opens first, allowing refrigerant to flow and causing the internal heat exchange temperature Tn to rise until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw falls below a second preset value, at which point the corresponding high-pressure solenoid valve opens. Finally, all liquid distribution expansion valves are switched to normal control, thus completing the mode switch. Compared to existing technologies, the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz or condensation temperature Tw can characterize the corresponding pressure difference. In this embodiment of the invention, the internal heat exchange temperature Tn is reasonably adjusted so that the high-pressure solenoid valve or low-pressure solenoid valve is opened after the internal heat exchange temperature Tn reaches the standard. 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 smaller, effectively solving the problem of large pipe vibration and noise in the existing technology.

[0013] Further, the step of opening the corresponding bypass expansion valve until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value, then opening the low-pressure solenoid valve of the corresponding pipeline and closing the corresponding bypass expansion valve includes:

[0014] Close the high-pressure solenoid valve and the liquid-dispensing expansion valve of the corresponding pipeline;

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

[0016] Open the bypass expansion valve on the corresponding bypass pipeline;

[0017] The internal heat exchange temperature Tn and evaporation temperature Tz of the indoor unit are obtained under the mode switching state;

[0018] The low-pressure solenoid valve is opened after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value.

[0019] Close the corresponding bypass expansion valve.

[0020] The control method for a fixed-mode air conditioner with both heating and cooling provided in this invention involves first closing the high-pressure solenoid valve and the liquid-dispensing expansion valve to completely cut off the flow pipeline when switching from heating to cooling control. Then, the liquid-dispensing expansion valve is set to a first preset opening degree. In this case, the bypass expansion valve on the corresponding bypass pipeline is opened, allowing refrigerant to flow into the compressor's suction side through the bypass expansion valve and bypass pipeline, thus reducing the pressure. The low-pressure solenoid valve can be fully opened once the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the first preset value. Because the flow pipeline is opened through the bypass expansion valve on the bypass pipeline, compared to directly opening the low-pressure solenoid valve, the refrigerant flow velocity can be effectively suppressed, thereby further suppressing vibration and refrigerant flow noise.

[0021] Further, the step of opening the bypass expansion valve on the corresponding bypass pipeline includes:

[0022] The bypass expansion valve on the corresponding bypass pipeline is gradually opened at a preset opening rate to gradually reduce the resistance of the bypass pipeline.

[0023] When the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, the current opening degree of the corresponding bypass expansion valve is maintained for a preset time.

[0024] The control method for a fixed-type air conditioner with cooling and heating provided in this embodiment of the invention, because the bypass expansion valve opens gradually rather than in one step, can further effectively control the refrigerant flow rate, thus preventing the refrigerant from rapidly flowing into the compressor suction side, thereby further suppressing vibration and refrigerant flow noise. Simultaneously, if the internal heat exchange temperature Tn drops too quickly, it indicates that the bypass expansion valve is opening too fast, leading to excessively fast refrigerant flow. This may cause new refrigerant flow noise or vibration problems. Therefore, by monitoring the rate of decrease of the internal heat exchange temperature Tn, if it is too fast, the current opening degree of the bypass expansion valve is maintained for a certain period to slow down the refrigerant flow rate and avoid refrigerant flow noise or vibration problems caused during the adjustment process.

[0025] Further, the first preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the liquid-dispensing expansion valve, and the first preset value is 10℃; the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the bypass expansion valve per second, the preset temperature drop rate is 0.5℃ / s, and the preset time is 5s.

[0026] The control method for a fixed-function air conditioner provided in this invention, by limiting a first preset opening degree and a preset opening rate, can, on the one hand, prevent excessive internal expansion opening that could lead to uncontrolled refrigerant flow, and on the other hand, reasonably limit the opening speed of the low-pressure solenoid valve to avoid refrigerant flow noise or vibration problems caused by excessive opening speed. Simultaneously, by limiting the preset temperature drop rate and preset time, the refrigerant flow speed can be precisely controlled, further slowing down the refrigerant flow and avoiding refrigerant flow noise or vibration problems.

[0027] Furthermore, the bypass pipe is a capillary pipe, and the resistance of the capillary pipe is greater than a preset resistance, so that the rate of decrease of the internal heat exchange temperature Tn is lower than the preset temperature drop rate.

[0028] The control method for a fixed-type air conditioner with cooling and heating provided in this invention uses a capillary tube to allow refrigerant to flow. When the resistance of the capillary tube is low, noise is caused by the rapid flow of refrigerant. When the resistance of the capillary tube is high, it takes time for the indoor unit to reach low pressure. This invention sets the critical resistance of the capillary tube, thereby saving as much time as possible while ensuring that no refrigerant flow noise or vibration is generated.

[0029] Further, the step of opening the liquid-distribution expansion valve of the corresponding pipeline until the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is lower than the second preset value, and then opening the high-pressure solenoid valve of the corresponding pipeline, includes:

[0030] Close the low-pressure solenoid valve of the corresponding pipeline;

[0031] Set the liquid distribution expansion valve of the corresponding pipeline to the second preset opening degree;

[0032] The internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit are obtained under the mode switching state;

[0033] When the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is lower than a second preset value, the corresponding high-pressure solenoid valve is opened.

[0034] 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 solenoid valve on the pipe corresponding to the indoor unit requiring mode switching, and sets the liquid expansion valve to the second preset opening degree. At this time, the refrigerant begins to flow back to other indoor units in heating mode through the liquid 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 liquid expansion valve has already equalized the pressure of the refrigerant, the pressure difference on both sides of the high-pressure solenoid valve is small, and the pipe vibration and flow noise generated during the refrigerant flow are small, further solving the problem of large pipe vibration and noise in the prior art.

[0035] Furthermore, after obtaining the indoor unit's internal heat exchange temperature Tn and condensing temperature Tw under the mode switching state, the method further includes:

[0036] Obtain the heat exchange temperature Tq of the indoor unit under other heating modes;

[0037] 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 third preset opening degree of the liquid expansion valve is reduced.

[0038] The control method for a simultaneous heating and cooling air conditioner provided in this embodiment of the 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 or vibration. Therefore, the opening of the distributor expansion valve can be reduced to decrease the refrigerant flow velocity and prevent 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 decrease in the outlet air temperature. Therefore, the opening of the distributor expansion valve can be reduced to prevent the heating function of the indoor unit in heating mode from being affected.

[0039] Further, the second preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the liquid-dispensing expansion valve; the third preset opening degree is 1 / 500 to 1 / 200 of the maximum opening degree of the liquid-dispensing expansion valve; the second preset value is 10℃; the preset temperature rise rate is 0.5℃ / s; and the preset temperature is 46℃.

[0040] The control method for a simultaneous heating and cooling air conditioner provided in this invention effectively ensures that the refrigerant achieves pressure equalization through the expansion valve to reduce pressure differential by limiting the initial opening and adjustment opening of the expansion valve. This avoids excessive noise during pressure equalization caused by an excessively large initial opening, and also prevents excessive impact on refrigerant flow when adjusting the expansion valve opening. This ensures reliable operation of the entire air conditioner during pressure equalization and improves user comfort. By reasonably limiting the preset temperature rise rate, the noise threshold during pressure equalization can be accurately defined, avoiding noise that could affect the user experience while ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible. Furthermore, by reasonably defining the preset temperature, the pressure equalization process can be accurately prevented from affecting other normally operating heating indoor units, while also ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible.

[0041] Furthermore, after setting the liquid distribution expansion valve of the corresponding pipeline to a second preset opening degree, the control method further includes:

[0042] The indoor unit's fan is in the stop mode switching state.

[0043] The air conditioning control method for simultaneous heating and cooling provided in this embodiment of the invention stops the corresponding fan after the liquid expansion valve is opened, which can avoid unnecessary airflow at different temperatures during mode switching and improve the user experience.

[0044] In another aspect, the present invention provides 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 compressor 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 compressor assembly is connected to the outdoor heat exchanger via a pipe. The high-pressure gas collection pipe is connected to the compressor 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 compressor assembly via a pipe and is also connected to multiple indoor units via multiple low-pressure gas distribution pipes.

[0047] The compressor assembly is used to compress the refrigerant and adjust its flow direction. Each liquid distribution pipe is equipped with a liquid distribution 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 heating mode 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 solenoid valve, which is used to open in cooling mode so that the refrigerant flows from the corresponding indoor unit to the low-pressure gas collector. Each low-pressure solenoid valve is also equipped with a bypass pipe at both ends, and a bypass expansion valve is installed on the bypass pipe. The bypass expansion valve is connected in parallel with the low-pressure solenoid valve. 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 of the steps of the control method for a simultaneous heating and cooling air conditioner provided in an embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of the structure of an air conditioner that can simultaneously heat and cool in other preferred embodiments of the present invention.

[0053] Explanation of reference numerals in the attached figures:

[0054] 100 - Simultaneous heating and cooling air conditioner; 110 - Outdoor unit; 111 - Outdoor heat exchanger; 112 - Compressor assembly; 113 - High-pressure manifold; 114 - Low-pressure manifold; 115 - Liquid distributor; 116 - Liquid distributor pipe; 117 - High-pressure gas distributor pipe; 118 - Low-pressure gas distributor pipe; 120 - Indoor unit; 130 - Liquid distributor expansion valve; 140 - High-pressure solenoid valve; 150 - Low-pressure solenoid valve; 160 - Bypass pipe; 161 - Bypass expansion valve. Detailed Implementation

[0055] 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.

[0056] 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.

[0057] To address the aforementioned problems, this invention provides a 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.

[0058] First Embodiment

[0059] See also 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.

[0060] 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 compressor 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 compressor assembly 112 is connected to the outdoor heat exchanger 111 through a pipe. The high-pressure gas collection pipe 113 is connected to the compressor 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 compressor assembly 112 through a pipe and is connected to the multiple indoor units 120 through multiple high-pressure gas distribution pipes 117. The unit 120 is connected via multiple low-pressure gas distribution pipes 118. The compressor assembly 112 is used to compress the refrigerant and adjust its flow direction. Each liquid distribution pipe 116 is equipped with a liquid distribution 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 heating mode, allowing the refrigerant to flow 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 solenoid valve 150, which is used to open in cooling mode, allowing the refrigerant to flow from the corresponding indoor unit 120 to the low-pressure gas collector 114. Each low-pressure solenoid valve 150 is also equipped with a bypass pipe 160 at both ends, and a bypass expansion valve 161 is installed on the bypass pipe 160. The bypass expansion valve 161 is connected in parallel with the low-pressure solenoid valve 150 for bypass communication.

[0061] In this embodiment, by additionally setting a bypass pipe 160 and an additional bypass expansion valve 161 on the bypass pipe 160, the refrigerant flow direction in the pipe can be adjusted by the bypass expansion valve 161 during mode switching. After adjustment, the low-pressure solenoid valve 150 is opened, which avoids the problem of excessive pressure difference and refrigerant flow noise or pipe vibration caused by directly opening the low-pressure solenoid valve 150. Furthermore, it does not require changing the original pipe structure, saving costs.

[0062] This embodiment provides a control method for a simultaneous cooling and heating air conditioner 100, which specifically includes the following steps:

[0063] S1: Set at least one indoor unit 120 to heating mode, open the corresponding pipe's liquid expansion valve 130 and high-pressure solenoid valve 140, and close the corresponding low-pressure solenoid valve 150 and bypass expansion valve 161.

[0064] In this embodiment, the bypass expansion valve 161 and the low-pressure solenoid valve 150 are connected in parallel through the bypass pipe 160. It should be noted that the parallel bypass mentioned in this embodiment refers to the two ends of the bypass pipe 160 being connected to the inlet and outlet of the low-pressure solenoid valve 150 respectively, thereby forming a bypass structure. The bypass expansion valve 161 is installed on the bypass pipe 160 and can control the flow direction of the refrigerant in the bypass pipe 160.

[0065] S2: Set at least one indoor unit 120 to cooling mode, open the corresponding pipe's liquid distribution expansion valve 130 and low-pressure solenoid valve 150, and close the corresponding high-pressure solenoid valve 140 and bypass expansion valve 161.

[0066] Specifically, either step S1 or step S2 can be performed, and can be set according to 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.

[0067] 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 S3 is executed: open the corresponding bypass expansion valve 161 until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the first preset value, then open the low-pressure solenoid valve 150 of the corresponding pipeline and close the corresponding bypass expansion valve 161.

[0068] 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 S4 is executed: the liquid distribution expansion valve 130 of the corresponding pipeline is opened until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than the second preset value, and then the high pressure solenoid valve 140 of the corresponding pipeline is opened.

[0069] S5: Transition the liquid expansion valve 130 to normal control to complete the mode switch.

[0070] 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. Noise typically arises when the pressure difference reaches a critical value, such as above 0.5 MPa. In this embodiment, by controlling the liquid-distribution expansion valve 130 or the bypass expansion valve 161, the pressure difference during loop switching can be controlled below 0.5 MPa. The pressure difference can be characterized by the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz or condensation temperature Tw. Both the first and second preset values ​​indicate that the pressure difference is 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.

[0071] In this embodiment, a bypass pipe 160 is added to both ends of the original low-pressure solenoid valve 150, and a bypass expansion valve 161 is installed on the bypass pipe 160. During actual control, cooling / heating control is first implemented. Initially, at least one indoor unit 120 is set to heating mode, the corresponding pipe's liquid distribution expansion valve 130 and high-pressure solenoid valve 140 are opened, and the corresponding low-pressure solenoid valve 150 and bypass expansion valve 161 are closed. Then, when one of the indoor units 120 switches from heating mode to cooling mode, the corresponding bypass expansion valve 161 is opened, refrigerant flows, and the internal heat exchange temperature Tn decreases until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value. After this, the corresponding low-pressure solenoid valve 150 is opened and the corresponding bypass expansion valve 161 is closed. Alternatively, initially, at least one indoor unit 120 is set to cooling mode, the corresponding pipe's liquid distribution expansion valve 130 and low-pressure solenoid valve 150 are opened, and the corresponding high-pressure solenoid valve 140 and bypass expansion valve 161 are closed. When one of the indoor units 120 switches from cooling mode to heating mode, the corresponding liquid-distribution expansion valve 130 is first opened, allowing refrigerant to flow and causing the internal heat exchange temperature Tn to rise until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a second preset value. Then, the corresponding high-pressure solenoid valve 140 is opened. Finally, the liquid-distribution expansion valve 130 is switched to normal control, thus completing the mode switching. Since the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz or condensing temperature Tw can represent the corresponding pressure difference, this embodiment of the invention reasonably adjusts the internal heat exchange temperature Tn so that the high-pressure solenoid valve 140 or the low-pressure solenoid valve 150 is opened only after the internal heat exchange temperature Tn reaches the target. Because the pressure difference on both sides of 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 the prior art.

[0072] Furthermore, in this embodiment, when switching the indoor unit 120 from heating mode to cooling mode and performing step S3, the following steps may be included:

[0073] S31: Close the high-pressure solenoid valve 140 and the liquid expansion valve 130 of the corresponding pipeline.

[0074] Specifically, when switching from heating mode to cooling mode, the high-pressure solenoid valve 140 can be closed first, and the liquid expansion valve 130 of the corresponding pipeline can be completely closed, thereby causing the refrigerant to temporarily stop.

[0075] S32: Set the liquid expansion valve 130 of the corresponding pipeline to the first preset opening degree.

[0076] Specifically, the indoor fan can be maintained at the speed before the change of operating mode, and the liquid expansion valve 130 corresponding to the indoor unit 120 in the mode switching state can be set to a first preset opening degree. The first preset opening degree can be 1 / 5 to 2 / 5 of the maximum opening degree of the liquid expansion valve 130, wherein the maximum opening degree of the liquid expansion valve 130 can be 500pls, and the liquid expansion valve 130 can be set to an opening degree of 120pls.

[0077] S33: Open the bypass expansion valve 161 on the corresponding bypass line 160.

[0078] Specifically, opening the bypass expansion valve 161 on the corresponding bypass line 160 allows refrigerant to flow into the compressor suction side through the bypass expansion valve 161 and the bypass line 160, reducing the pressure until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value, at which point the low-pressure solenoid valve 150 can be fully opened. Because the flow line is opened via the bypass expansion valve 161 on the bypass line 160, compared to directly opening the low-pressure solenoid valve 150, the refrigerant flow velocity can be effectively suppressed, thereby further suppressing vibration and refrigerant flow noise.

[0079] Specifically, when opening the bypass expansion valve 161, it is preferable to gradually open the bypass expansion valve 161 on the corresponding bypass pipeline 160 according to a preset opening rate, so as to gradually reduce the resistance of the bypass pipeline 160; and when the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, the current opening of the bypass expansion valve 161 is maintained for a preset time.

[0080] The preset opening rate can be 1 / 500 to 1 / 200 of the maximum opening of the bypass expansion valve 161, and the maximum opening of the bypass expansion valve 161 can be 500 pls. Preferably, the bypass expansion valve 161 can be gradually opened at a rate of 2 pls / s. Since the opening process of the bypass expansion valve 161 is gradual and not a one-step process, the flow rate of the refrigerant can be further effectively controlled, that is, the refrigerant is prevented from flowing rapidly into the compressor suction side, thereby further suppressing vibration and refrigerant flow noise.

[0081] It should be noted that when the internal heat exchange temperature Tn drops too quickly, it indicates that the bypass expansion valve 161 is opening too fast, resulting in excessive refrigerant flow speed. This may cause new 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 bypass expansion valve 161 should be maintained for a certain period of time to slow down the refrigerant flow speed and avoid refrigerant flow noise or vibration problems caused during the adjustment process.

[0082] S34: Obtain the internal heat exchange temperature Tn and evaporation temperature Tz of the indoor unit 120 under the mode switching state.

[0083] 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.

[0084] S35: Open the low-pressure solenoid valve 150 after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the first preset value.

[0085] Specifically, the first preset value can be 10℃. When 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 solenoid valve 150 is less than 0.5MPa. At this time, the low-pressure solenoid valve 150 can be fully opened without generating vibration and flow noise.

[0086] S36: Close the corresponding bypass expansion valve 161.

[0087] Specifically, after the low-pressure solenoid valve 150 is opened, the refrigerant flows through the main pipe. At this time, the bypass expansion valve 161 can be closed to prevent the refrigerant from flowing through the bypass pipe 160.

[0088] In this embodiment, the first preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the liquid-liquid expansion valve 130, and the first preset value is 10°C; the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the bypass expansion valve 161 per second, the preset temperature drop rate is 0.5°C / s, and the preset time is 5s. By limiting the first 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 solenoid valve 150, avoiding refrigerant flow noise or vibration problems caused by excessive opening speed. At the same time, by limiting the preset temperature drop rate and the 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.

[0089] In other preferred embodiments of the invention, see [link to other embodiments]. Figure 5 The bypass pipe 160 can be a capillary tube, and the resistance of the capillary tube is greater than the preset resistance, so that the rate of decrease of the internal heat exchange temperature Tn is lower than the preset temperature drop rate. In this case, when the bypass expansion valve 161 is opened, it can be fully opened directly, or the bypass expansion valve 161 can be replaced with a solenoid shut-off valve, such as... Figure 5The resistance of the capillary tube is related to its diameter and length. It can be limited by restricting the diameter and length of the capillary tube to ensure that the resistance is greater than a preset limit. Using a capillary tube for refrigerant flow can cause noise due to rapid refrigerant flow when the resistance is low, and time is required for the indoor unit to reach low pressure within 120°C when the resistance is high. This invention sets a critical resistance for the capillary tube, thereby minimizing time while ensuring that refrigerant flow noise or vibration is not generated.

[0090] Furthermore, in this embodiment, when switching the indoor unit 120 from cooling mode to heating mode and performing step S4, the following steps may be included:

[0091] S41: Close the low-pressure solenoid valve 150 of the corresponding pipeline.

[0092] Specifically, the low-pressure solenoid valve 150 can be closed first, so that the refrigerant stops flowing in the refrigeration circuit, thereby stopping the refrigeration.

[0093] S42: Set the liquid expansion valve 130 of the corresponding pipeline to the second preset opening degree.

[0094] Specifically, the second preset opening degree can be 1 / 5 to 2 / 5 of the maximum opening degree of the liquid distribution expansion valve 130. Preferably, the maximum opening degree of the liquid distribution expansion valve 130 can be 500pls, so the opening degree of the liquid distribution expansion valve 130 can be set to 120pls.

[0095] S33: The fan of indoor unit 120 in the stop mode switching state.

[0096] Specifically, stopping the corresponding fan after opening the liquid expansion valve 130 can avoid unnecessary airflow at high temperatures during mode switching, thus improving the user experience.

[0097] S34: Obtain the internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit 120 under the mode switching state.

[0098] 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.

[0099] S35: Obtain the heat exchange temperature Tq of indoor unit 120 under other heating modes.

[0100] 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.

[0101] When the rate of increase of the internal heat exchange temperature Tn exceeds the preset temperature rise rate, step S36 is executed: reduce the third preset opening degree of the liquid distribution expansion valve 130.

[0102] 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 third preset opening degree of the liquid expansion valve 130.

[0103] 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.

[0104] 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 liquid distribution 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:

[0105] 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.

[0106] 2. The heat exchange temperature Tq of the indoor heating unit 120 is below 46℃.

[0107] 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 liquid distribution expansion valve 130 can be reduced to decrease the refrigerant flow velocity and avoid vibration or refrigerant flow noise during the adjustment process. In addition, 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 liquid distribution expansion valve 130 can be reduced to avoid affecting the heating function of the indoor unit 120 in heating mode.

[0108] S37: When the difference between the internal heat exchange temperature Tn and the condensation temperature Tw is lower than the second preset value, the corresponding high-pressure solenoid valve 140 is opened.

[0109] 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.

[0110] When actually executing step S3, that is, when switching from cooling to heating, the low-pressure solenoid valve 150 on the pipe corresponding to the indoor unit 120 that needs to switch modes is first closed, and the liquid expansion valve 130 is set to the second preset opening degree. At this time, the refrigerant begins to flow back to other indoor units 120 in heating mode through the liquid expansion valve 130, thereby equalizing the pressure with other indoor units 120 in heating mode. Under these circumstances, the internal heat exchange temperature Tn of the indoor unit 120 that has switched 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 liquid expansion valve 130 has already equalized the pressure of the refrigerant, the pressure difference on both sides of the high-pressure solenoid valve 140 is small, and the pipe vibration and flow noise generated during the refrigerant flow are small, further solving the problem of large pipe vibration and noise in the prior art.

[0111] Furthermore, the second preset opening is 1 / 5 to 2 / 5 of the maximum opening of the liquid distribution expansion valve 130; the third preset opening is 1 / 500 to 1 / 200 of the maximum opening of the liquid distribution expansion valve 130; the second preset value is 10℃; the preset temperature rise rate is 0.5℃ / s; and the preset temperature is 46℃. By limiting the initial and adjusted opening of the liquid distribution expansion valve 130, it is possible to effectively ensure that the refrigerant is evenly pressurized through the liquid distribution expansion valve 130 to reduce the pressure difference, while avoiding excessive noise during the pressure equalization process caused by an excessively large initial opening. It also avoids excessive influence on the refrigerant flow when adjusting the opening of the liquid distribution expansion valve 130, ensuring reliable operation of the overall air conditioner during the pressure equalization process and improving user comfort. By reasonably limiting the preset temperature rise rate, the noise threshold value during the pressure equalization process can be accurately defined, avoiding noise that affects the experience while ensuring rapid refrigerant flow to achieve pressure equalization as quickly as possible. At the same time, by reasonably defining the preset temperature, it is possible to accurately avoid the pressure equalization process from affecting other normally operating heating indoor units 120, while also ensuring that the refrigerant flows quickly to achieve pressure equalization as soon as possible.

[0112] In summary, the control method and the simultaneous cooling and heating air conditioner 100 provided in this embodiment add a bypass pipe 160 to both ends of the original low-pressure solenoid valve 150, and install a bypass expansion valve 161 on the bypass pipe 160. In actual control, the cooling / heating function is first realized by setting at least one indoor unit 120 to the heating mode, opening the liquid distribution expansion valve 130 and the high-pressure solenoid valve 140 of the corresponding pipe, and closing the corresponding low-pressure solenoid valve 150 and the bypass expansion valve 161. Then, when one of the indoor units 120 switches from heating mode to cooling mode, the corresponding bypass expansion valve 161 opens, refrigerant flows, and the internal heat exchange temperature Tn decreases until the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than a first preset value. Then, the corresponding low-pressure solenoid valve 150 opens and the corresponding bypass expansion valve 161 closes. Alternatively, at least one indoor unit 120 is set to cooling mode, the corresponding pipe's liquid distribution expansion valve 130 and low-pressure solenoid valve 150 are opened, and the corresponding high-pressure solenoid valve 140 and bypass expansion valve 161 are closed. When one of the indoor units 120 switches from cooling mode to heating mode, the corresponding pipe's liquid distribution expansion valve 130 is first opened, refrigerant flows, and the internal heat exchange temperature Tn increases until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than a second preset value. Then, the corresponding high-pressure solenoid valve 140 opens. Finally, the liquid distribution expansion valve 130 is switched to normal control, thus completing the mode switching. In this embodiment, the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz or condensation temperature Tw can characterize the corresponding pressure difference. This embodiment of the invention adjusts the internal heat exchange temperature Tn appropriately, ensuring that the internal heat exchange temperature Tn reaches the target before opening the high-pressure solenoid valve 140 or the low-pressure solenoid valve 150. Because the pressure difference across the valve has been reduced 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 the prior art. Simultaneously, during mode switching, the refrigerant flow rate is effectively controlled by controlling each valve, avoiding noise problems caused during mode switching.

[0113] 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: Open the corresponding liquid expansion valve (130) and high-pressure solenoid valve (140) of the pipeline, and close the corresponding low-pressure solenoid valve (150) and bypass expansion valve (161) so that at least one of the indoor units (120) operates in heating mode, wherein the bypass expansion valve (161) and the low-pressure solenoid valve (150) are connected in parallel through the bypass pipeline (160); When one of the indoor units (120) switches from heating mode to cooling mode, the high-pressure solenoid valve (140) and the liquid expansion valve (130) of the corresponding pipeline are closed, the liquid expansion valve (130) of the corresponding pipeline is set to the first preset opening degree, the bypass expansion valve (161) on the corresponding bypass pipeline (160) is opened, and the low-pressure solenoid valve (150) of the corresponding pipeline is opened and the corresponding bypass expansion valve (161) is closed after the difference between the internal heat exchange temperature Tn and the evaporation temperature Tz is lower than the first preset value. The liquid distribution expansion valve (130) is switched to normal control to complete the mode switching; Open the liquid distribution expansion valve (130) and low-pressure solenoid valve (150) of the corresponding pipeline, and close the corresponding high-pressure solenoid valve (140) and bypass expansion valve (161) so that at least one of the indoor units (120) operates in cooling mode. When one of the indoor units (120) switches from cooling mode to heating mode, the low-pressure solenoid valve (150) of the corresponding pipeline is closed, and the liquid expansion valve (130) of the corresponding pipeline is set to the second preset opening degree until the difference between the internal heat exchange temperature Tn and the condensing temperature Tw is lower than the second preset value, then the high-pressure solenoid valve (140) of the corresponding pipeline is opened. The liquid expansion valve (130) is switched to normal control to complete the mode switch.

2. The control method for a simultaneous cooling and heating air conditioner according to claim 1, characterized in that, The step of opening the bypass expansion valve (161) on the corresponding bypass line (160) includes: The bypass expansion valve (161) on the corresponding bypass pipeline (160) is gradually opened at a preset opening rate to gradually reduce the resistance of the bypass pipeline (160); When the rate of decrease of the internal heat exchange temperature Tn exceeds the preset temperature drop rate, the current opening degree of the corresponding bypass expansion valve (161) is maintained for a preset time.

3. The control method for a simultaneous cooling and heating air conditioner according to claim 2, characterized in that, The first preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the liquid-dispensing expansion valve (130), and the first preset value is 10℃; the preset opening rate is 1 / 500 to 1 / 200 of the maximum opening degree of the bypass expansion valve (161) per second, the preset temperature drop rate is 0.5℃ / s, and the preset time is 5s.

4. The control method for a simultaneous cooling and heating air conditioner according to claim 1, characterized in that, The bypass pipe (160) is a capillary pipe, and the resistance of the capillary pipe is greater than the preset resistance, so that the rate of decrease of the internal heat exchange temperature Tn is lower than the preset temperature drop rate.

5. The control method for a simultaneous cooling and heating air conditioner according to claim 1, characterized in that, After acquiring the internal heat exchange temperature Tn and condensing temperature Tw of the indoor unit (120) in the mode switching state, the 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) is lower than the preset temperature in other heating modes, the corresponding liquid expansion valve (130) is adjusted to the third preset opening degree.

6. The control method for a simultaneous cooling and heating air conditioner according to claim 5, characterized in that, The second preset opening degree is 1 / 5 to 2 / 5 of the maximum opening degree of the liquid-distributing expansion valve (130); the third preset opening degree is 1 / 500 to 1 / 200 of the maximum opening degree of the liquid-distributing expansion valve (130); the second preset value is 10℃; the preset temperature rise rate is 0.5℃ / s; and the preset temperature is 46℃.

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

8. A simultaneous cooling and heating air conditioner, applicable to the control method of the simultaneous cooling and heating air conditioner as described in any one of claims 1-7, characterized in that, The air conditioner that provides both heating and cooling includes: Multiple indoor units (120); An outdoor unit (110) includes an outdoor heat exchanger (111), a compressor 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 multiple indoor units (120) via multiple distributor pipes (116). The outdoor heat exchanger (111) is connected to the distributor (115) via a pipe. The compressor assembly (112) is connected to the outdoor heat exchanger (111) via a pipe. The high-pressure gas collection pipe (113) is connected to the compressor assembly (112) via a pipe and is connected to multiple indoor units (120) via multiple high-pressure gas distribution pipes (117). The low-pressure gas collection pipe (114) is connected to the compressor assembly (112) via a pipe and is connected to multiple indoor units (120) via multiple low-pressure gas distribution pipes (118). The compressor assembly (112) is used to compress the refrigerant and adjust the refrigerant flow direction. Each liquid distribution pipe (116) is provided with a liquid distribution expansion valve (130), and each high-pressure gas distribution pipe (117) is provided 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 collection pipe to the corresponding indoor unit (120). Each low-pressure gas distribution pipe (118) is provided with a low-pressure solenoid valve (150). The low-pressure solenoid 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 collection pipe (114). Each low-pressure solenoid valve (150) is also provided with a bypass pipe (160) at both ends. A bypass expansion valve (161) is provided on the bypass pipe (160). The bypass expansion valve (161) is connected in parallel with the low-pressure solenoid valve (150).

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