A multi-connection system and an oil return control method for the multi-connection system

Abstract

The present invention provides a multi-split system and a return oil control method for the multi-split system. The multi-split system includes: a refrigerant circulation pipeline, a compressor, a first heat exchanger and a second heat exchanger, wherein the compressor, the first heat exchanger and the second heat exchanger are connected through the refrigerant circulation pipeline; a pressure sensor, wherein the pressure sensor is arranged on the refrigerant circulation pipeline, and the pressure sensor is arranged between the first heat exchanger and the second heat exchanger; a pressurizing device, wherein the pressurizing device is arranged on the refrigerant circulation pipeline, and the pressurizing device is arranged between the pressure sensor and the second heat exchanger. The present invention solves the technical problems that the presence of an oil return bend in a multi-split system occupies space, is difficult to maintain, and also causes some oil to accumulate at the oil return pipe when the multi-split system is running, and at the same time, the bend in the pipe reduces the flow efficiency of the refrigerant.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a multi-split system and an oil return control method of the multi-split system. Background Art

[0002] There is usually a certain height difference between the second heat exchanger and the first heat exchanger of the multi-split system during installation. The unit manual generally stipulates the installation height difference limit of the multi-split product. When the multi-split system is connected with a high height difference, the outdoor heat exchanger is on the top and the indoor heat exchanger is on the bottom. When the oil return operation is performed, in order to ensure that the lubricating oil can smoothly return to the compressor, it is usually necessary to add an oil return bend every 10m at the liquid pipe to ensure the stability of the oil return.

[0003] However, in actual use, there is a problem: the existence of the oil return bend in the multi-split system will take up space and make maintenance difficult. It will also cause some oil to accumulate in the oil return pipe when the multi-split system is running. At the same time, the bend in the pipe will reduce the flow efficiency of the refrigerant. Summary of the invention

[0004] The present invention solves the technical problems that the existence of the oil return bend in the multi-split system occupies space, is difficult to maintain, causes partial oil accumulation in the oil return pipe when the multi-split system is running, and the bend in the pipe reduces the flow efficiency of the refrigerant.

[0005] To solve the above problems, the present invention provides a multi-split system, including: a refrigerant circulation pipeline, a compressor, a first heat exchanger and a second heat exchanger, the compressor, the first heat exchanger and the second heat exchanger are connected through the refrigerant circulation pipeline; a pressure sensor, the pressure sensor is arranged on the refrigerant circulation pipeline, and the pressure sensor is arranged between the first heat exchanger and the second heat exchanger; a pressurizing device, the pressurizing device is arranged on the refrigerant circulation pipeline, and the pressurizing device is arranged between the pressure sensor and the second heat exchanger.

[0006] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the multi-split system of the present application cancels the oil return bend during the high-drop installation process, the compressor, the first heat exchanger, the pressurizing device and the second heat exchanger are connected in sequence through the refrigerant circulation pipeline, the pressure sensor is arranged between the first heat exchanger and the pressurizing device, the pressure at the liquid pipe of the first heat exchanger can be obtained through the pressure sensor, and the pressure change is detected by the pressure sensor to dynamically control the operation of the pressurizing device in real time to achieve the function of controlling the refrigerant flow rate; at the same time, a pressurizing device is added to the refrigerant circulation pipeline to adjust the pressure of the refrigerant circulation pipeline, thereby changing the flow rate of the refrigerant, thereby changing the speed at which the refrigerant flows back to the compressor. Through the combined control of the pressure sensor and the pressurizing device, the multi-split system can replace the role of the oil return bend when operating at a high drop, achieve the purpose of canceling the oil return bend, and achieve the timely return of the retained oil to the compressor, ensuring the stable and safe operation of the multi-split system.

[0007] On the other hand, an embodiment of the present invention further provides an oil return control method for a multi-split system, which is applied to a multi-split system such as any embodiment of the present invention. The oil return control method includes: after the multi-split system is running, detecting whether the multi-split system enters the oil return operation mode; when the multi-split system enters the oil return operation mode, obtaining a first pressure value of the pressure sensor; controlling the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate; wherein the operating parameters include: the operating state of the pressurizing device, and the operating frequency of the compressor.

[0008] Compared with the prior art, the technical effect achieved by adopting this technical scheme is as follows: after the multi-split system is running, it is detected whether the multi-split system enters the oil return operation mode; when the multi-split system enters the oil return operation mode, the compressor should be at the preset frequency value for oil return, but when it just enters the oil return operation mode, the pressure is insufficient and the refrigerant flow rate is low. It takes a period of time to drive the oil back to the compressor, and the oil cannot be quickly returned to the compressor. Therefore, a pressure sensor is added to the liquid pipe shut-off valve of the first heat exchanger. When the first pressure value is less than the preset pressure value, the pressurizing device is controlled to start to pressurize, thereby increasing the refrigerant flow rate in the refrigerant circulation pipeline until the value of the pressure sensor is equal to the preset pressure value. During the pressurization process, the operating frequency of the compressor is increased to the frequency set by the program value, and the pressure required to be provided by the pressurizing device is reduced.

[0009] In one example of the present invention, the operating parameters of the multi-split system are controlled according to the first pressure value and the preset pressure value to control the refrigerant flow rate, including: when the first pressure value is less than the preset pressure value, controlling the pressurizing device to start running and controlling the operating frequency to the preset frequency value to increase the refrigerant flow rate; monitoring the first pressure value in real time, and updating the first pressure value.

[0010] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the pressure provided by the compressor can be obtained through the first pressure value: after the multi-split system is running, when the first pressure value is less than the preset pressure value, it means that the pressure provided by the compressor is small and the rate of compressed gas is small; therefore, after the multi-split system enters the oil return operation mode, it is necessary to increase the operating frequency of the compressor to reach the preset frequency value when it is detected that the first pressure value is too small, and to increase the pressurization by starting the pressurizing device to increase the refrigerant flow rate of the refrigerant in the refrigerant circulation pipeline.

[0011] In one example of the present invention, after real-time monitoring of the first pressure value and updating the first pressure value, the return oil control method also includes: judging the size of the first pressure value and the preset pressure value; when the first pressure value reaches the preset pressure value, controlling the pressurizing device to stop running; cyclically executing detection of whether the multi-split system enters the return oil operation mode; cyclically executing when the multi-split system enters the return oil operation mode, obtaining the first pressure value of the pressure sensor; cyclically executing control of the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate.

[0012] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: in the process of the multi-split system performing the oil return operation mode, the size of the first pressure value and the preset pressure value is judged in real time, and the added pressure is automatically adjusted by the pressurizing device to control the first pressure value monitored by the pressure sensor to reach the preset pressure value, thereby achieving dynamic balance; the steps are executed cyclically, so that the first pressure value can be continuously updated, and the operating parameters of the multi-split system can be adjusted according to the real-time updated first pressure value, thereby further improving the user experience.

[0013] In one example of the present invention, the oil return control method further includes: obtaining an installation height difference between the first heat exchanger and the second heat exchanger; obtaining a refrigerant density of the refrigerant; and obtaining a preset pressure value according to the installation height difference and the refrigerant density.

[0014] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the preset pressure value is the pressure value that can be returned to the compressor during the oil return operation of the multi-split system unit, and the value of the preset pressure value is related to the oil density, gravity acceleration and the installation height difference between the inner and outer units.

[0015] In one example of the present invention, after the multi-split system is running, it is detected whether the multi-split system enters the oil return operation mode, including: after the multi-split system is running, obtaining the operation parameters of the multi-split system; judging whether the multi-split system meets the oil return condition according to the operation parameters; and when the multi-split system meets the oil return condition, controlling the multi-split system to enter the oil return operation mode.

[0016] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the controller is preset with the oil return condition. After obtaining the operating parameters, the operating parameters will be compared with the oil return condition to determine whether it is necessary to enter the oil return operation mode. When the multi-split system meets the oil return condition, the multi-split system is controlled to enter the oil return operation mode.

[0017] In one example of the present invention, after the multi-split system is running, the operating parameters of the multi-split system are obtained, including: obtaining the operating frequency of the compressor; obtaining the operating time of the multi-split system when the operating frequency is less than a frequency threshold.

[0018] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by obtaining the operating frequency of the compressor, and when the operating frequency of the compressor is less than the frequency threshold (the compressor is in low-frequency operation at this time), the accumulated oil return time (also known as the operating time of the multi-split system when the operating frequency of the compressor is less than the frequency threshold) is accumulated. By obtaining the operating frequency and the accumulated oil return time, the operating status of the multi-split system is monitored from multiple angles, so that the timing of whether the multi-split system needs oil return can be better judged, a better oil return effect can be ensured, and the impact on the normal use time period of the multi-split system can be minimized. The oil return conditions are set by multiple operating parameters, so that the oil return conditions are more reasonable and the oil return effect is better.

[0019] In an example of the present invention, the oil return condition is: the operating time is greater than or equal to a preset time.

[0020] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the oil return condition can be pre-implanted into the controller, and in different operating modes, the specific standards of the oil return condition will be adjusted accordingly.

[0021] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) The pressure sensor detects the pressure change to dynamically control the operation of the pressurizing device in real time to control the refrigerant flow rate. At the same time, a pressurizing device is added to the refrigerant circulation pipeline to adjust the pressure of the refrigerant circulation pipeline, thereby changing the refrigerant flow rate, thereby changing the speed at which the refrigerant flows back to the compressor; (2) Through the combined control of the pressure sensor and the pressurizing device, the multi-split system can replace the role of the oil return bend when operating at a high drop, achieve the purpose of eliminating the oil return bend, and enable the retained oil to return to the compressor in time, ensuring the stable and safe operation of the multi-split system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of a multi-connection system provided in Embodiment 1 of the present invention; Figure 2A flow chart of an oil return control method for a multi-split system provided in Embodiment 2 of the present invention; Figure 3 A schematic diagram of the installation of a multi-connection system provided in the first embodiment of the present invention; Figure 4 This is a schematic diagram of the installation of a multi-split system using an oil return bend in the prior art.

[0023] Description of reference numerals: 100. Refrigerant circulation pipeline; 101. Pressure sensor; 102. Pressurizing device; 103. First valve; 104. Second valve; 110. Compressor; 121. First heat exchanger; 122. Second heat exchanger; 130. Oil separator; 140. Gas-liquid separator. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] [Example 1] See also Figure 1 , which is a structural diagram of a multi-connection system provided by the first embodiment of the present invention, combined with Figure 3-Figure 4 The multi-split system includes: a refrigerant circulation pipeline 100, a compressor 110, a first heat exchanger 121 and a second heat exchanger 122, the compressor 110, the first heat exchanger 121 and the second heat exchanger 122 are connected through the refrigerant circulation pipeline 100; a pressure sensor 101, the pressure sensor 101 is arranged on the refrigerant circulation pipeline 100, and the pressure sensor 101 is arranged between the first heat exchanger 121 and the second heat exchanger 122; a pressurizing device 102, the pressurizing device 102 is arranged on the refrigerant circulation pipeline 100, and the pressurizing device 102 is arranged between the pressure sensor 101 and the second heat exchanger 122.

[0026] In a specific embodiment, see Figure 4, because the existence of the oil return bend in the multi-split system will take up space and be difficult to maintain, it will also cause some oil to accumulate at the oil return pipe when the multi-split system is running, and the pipe bending will reduce the flow efficiency of the refrigerant. Therefore, the multi-split system of the present application cancels the oil return bend during the high-drop installation process, and the compressor 110, the first heat exchanger 121, the pressurizing device 102 and the second heat exchanger 122 are connected in sequence through the refrigerant circulation pipeline 100. The pressure sensor 101 is arranged between the first heat exchanger 121 and the pressurizing device 102. The pressure at the liquid pipe of the first heat exchanger 121 can be obtained by the pressure sensor 101. The pressure change is detected by the pressure sensor 101 to dynamically control the operation of the pressurizing device 102 in real time to achieve the effect of controlling the refrigerant flow rate; at the same time, a pressurizing device 102 is added to the refrigerant circulation pipeline 100 to adjust the pressure of the refrigerant circulation pipeline 100, thereby changing the flow rate of the refrigerant, thereby changing the speed at which the refrigerant flows back to the compressor 110. Through the combined control of the pressure sensor 101 and the pressurizing device 102, the function of the oil return bend can be replaced when the multi-split system is operating at a high drop, thereby achieving the purpose of canceling the oil return bend and enabling the retained oil to return to the compressor 110 in time, thereby ensuring the stable and safe operation of the multi-split system.

[0027] Specifically, when the multi-split system enters the oil return operation mode, the compressor 110 should return oil at a frequency set by a program value. However, when it just enters the oil return operation mode, the pressure is insufficient and the refrigerant flow rate is low. It takes a period of time to drive the oil back to the compressor 110, and the oil cannot return to the compressor 110 quickly. Therefore, a pressure sensor 101 is added to the liquid pipe shut-off valve of the first heat exchanger 121; when the value of the pressure sensor 101 is less than the preset pressure value, the pressurizing device 102 is controlled to start and pressurize to increase the refrigerant flow rate in the refrigerant circulation pipeline 100 until the value of the pressure sensor 101 is equal to the preset pressure value. During the pressurization process, the operating frequency of the compressor 110 is increased to the frequency set by the program value, and the pressure required to be provided by the pressurizing device 102 is reduced.

[0028] Preferably, the first heat exchanger 121 is an outdoor heat exchanger, the second heat exchanger 122 includes at least one indoor heat exchanger, and the pressurizing device 102 is a pump.

[0029] Furthermore, the multi-split system also includes: an oil separator 130 and a gas-liquid separator 140, the oil separator 130 is connected between the compressor 110 and the first heat exchanger 121 through the refrigerant circulation pipeline 100; the gas-liquid separator 140 is connected between the second heat exchanger 122 and the compressor 110 through the refrigerant circulation pipeline 100.

[0030] Specifically, the oil separator 130 is used to separate the gas and oil of the multi-split system. Specifically, the oil separator 130 separates the lubricating oil in the high-pressure steam discharged from the compressor 110, thereby ensuring the reliability of the compressor 110 and ensuring the safe and efficient operation of the multi-split system. Since the compressor 110 can only compress gas, if the compressor 110 "returns liquid", it is easy to cause damage to the compressor 110. Therefore, a gas-liquid separator 140 for separating gas and liquid is added to the multi-split system. If the refrigerant is not completely evaporated in the second heat exchanger 122, the gas-liquid mixed refrigerant can first flow back to the gas-liquid separator 140 and separate the gas therefrom, so that the separated gas flows back to the compressor 110, and the separated liquid remains in the gas-liquid separator 140, which has a buffering effect on the gas-liquid separator 140.

[0031] Furthermore, the multi-split system also includes: a first valve 103 and a second valve 104, the first valve 103 is connected between the pressure sensor 101 and the pressurizing device 102 through the refrigerant circulation pipeline 100; the second valve 104 is connected between the second heat exchanger 122 and the gas-liquid separator 140 through the refrigerant circulation pipeline 100.

[0032] Specifically, the first valve 103 is a small valve connected to the liquid pipe of the multi-connected system for liquid supply; the second valve 104 is a large valve connected to the air pipe of the multi-connected system for air return.

[0033] [Example 2] See also Figure 2 , which is a flow chart of an oil return control method for a multi-split system provided by a second embodiment of the present invention. This embodiment also provides an oil return control method for a multi-split system, which is applied to a multi-split system as in any embodiment of the present invention, and includes: Step S100: After the multi-split system is running, detecting whether the multi-split system enters the oil return operation mode; Step S200: when the multi-split system enters the oil return operation mode, obtaining a first pressure value of the pressure sensor; Step S300: controlling the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate; The operating parameters include: the operating state of the pressurizing device and the operating frequency of the compressor.

[0034] In a specific embodiment, after the multi-split system is running, it is detected whether the multi-split system enters the oil return operation mode; when the multi-split system enters the oil return operation mode, the compressor should be at a frequency set by a program value (that is, a frequency preset value) for oil return, but when it just enters the oil return operation mode, the pressure is insufficient and the refrigerant flow rate is low. It takes a period of time to drive the oil back to the compressor, and the oil cannot be quickly returned to the compressor. Therefore, a pressure sensor is added to the liquid pipe shut-off valve of the first heat exchanger. When the value of the pressure sensor (that is, the first pressure value) is less than the preset pressure value, the pressurizing device is controlled to start pressurizing to increase the refrigerant flow rate in the refrigerant circulation pipeline until the value of the pressure sensor is equal to the preset pressure value. During the pressurization process, the operating frequency of the compressor is increased to the frequency set by the program value, and the pressure required to be provided by the pressurizing device is reduced.

[0035] Preferably, the first heat exchanger is an outdoor heat exchanger, and the second heat exchanger is an indoor heat exchanger.

[0036] Furthermore, step S300 includes: Step S310: When the first pressure value is less than the preset pressure value, the pressurizing device is controlled to start running and the running frequency is controlled to be the preset frequency value to increase the refrigerant flow rate; Step S320: monitor the first pressure value in real time and update the first pressure value.

[0037] Specifically, the pressure provided by the compressor can be obtained through the first pressure value: after the multi-split system is running, when the first pressure value is less than the preset pressure value, it means that the pressure provided by the compressor is small and the rate of compressed gas is small; therefore, after the multi-split system enters the oil return operation mode, it is necessary to increase the operating frequency of the compressor to reach the preset frequency value when the first pressure value is detected to be too small, and to start the pressurizing device to increase the refrigerant flow rate of the refrigerant in the refrigerant circulation pipeline. Preferably, the frequency preset value is set according to the program value, and different refrigerants or unit brands have different fixed values. The preferred value of the frequency preset value in this application is 65HZ.

[0038] In the process of controlling the operating parameters of the multi-split system to increase the refrigerant flow rate, the compressor frequency increases, the rate of compressed gas increases, the refrigerant flow rate increases, the compressor speed increases, and the high-pressure pressure increases. In the air-conditioning system, 1Hz means that the compressor and motor in the air-conditioning system perform compression and rotation work once per second. The compressor operating frequency is directly proportional to the compressor speed. At this time, according to the formula: n , where n is the compressor speed, f is the power frequency, and p is the number of pole pairs of the motor's rotating magnetic field. The gas output by the compressor can be expressed by the following formula: ,in, is the gas delivery volume, t is the vortex wall thickness, is the pitch of the scroll body, h is the height of the scroll body, and N is the logarithm of the compression chamber; the output gas of the compressor is also proportional to the rotation speed. The higher the frequency, the larger the output gas volume.

[0039] At the same time, the first pressure value is monitored in real time and updated. That is to say, when the multi-connected system enters the oil return operation mode, the first pressure value can be acquired and updated in real time to control the operation status of the pressurizing device in real time.

[0040] Preferably, when the multi-split system enters the oil return operation mode, when the first pressure value is less than the preset pressure value, the pressurizing device is controlled to start, and the operating frequency of the compressor is controlled to remain at the preset frequency value. After the oil return operation mode executes the first preset time, the oil return operation mode is exited.

[0041] Furthermore, after step S320, the oil return control method further includes: Determine the magnitude of the first pressure value and the preset pressure value; When the first pressure value reaches the preset pressure value, the pressurizing device is controlled to stop running; Cycle execution to detect whether the multi-connection system has entered the oil return operation mode; When the multi-connected system enters the oil return operation mode, the first pressure value of the pressure sensor is obtained; The cycle executes the control of the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate.

[0042] Specifically, during the oil return operation mode of the multi-split system, the first pressure value and the preset pressure value are judged in real time, and the pressure added is automatically adjusted by the pressurizing device to control the first pressure value monitored by the pressure sensor to reach the preset pressure value to achieve dynamic balance. As the pressure provided by the compressor continues to rise, the pressure required to be provided by the pressurizing device decreases until the pressurizing device stops running (that is, the pressurizing device does not need to provide pressure). At this time, the pressure sensor no longer determines the pressure at this time. and At this time, the operation of the compressor alone is sufficient to quickly return the retained oil to the compressor until the oil return is completed. At this time, the multi-split system operates in the normal mode and cyclically executes steps S100-S300, which can continuously update the first pressure value and adjust the operating parameters of the multi-split system according to the real-time updated first pressure value, further improving the user experience. Among them, is the first pressure value, is the preset pressure value.

[0043] Furthermore, the oil return control method further includes: Obtaining an installation height difference between the first heat exchanger and the second heat exchanger; Obtaining the refrigerant density of the refrigerant; Obtain the preset pressure value based on the installation height and refrigerant density.

[0044] Specifically, the preset pressure value is the pressure value that can be returned to the compressor when the multi-split system unit returns to oil. The value of the preset pressure value is related to the oil density, gravity acceleration and the installation height difference between the inner and outer units. ,in, is the oil density in ; g is the acceleration due to gravity, and the value of g is 9.8 ; H is the installation height difference between the inner and outer units, in meters.

[0045] Furthermore, step S100 includes: Step S110: After the multi-link system is running, obtaining the operating parameters of the multi-link system; Step S120: judging whether the multi-connected system meets the oil return condition according to the operating parameters; Step S130: When the multi-split system meets the oil return condition, the multi-split system is controlled to enter the oil return operation mode.

[0046] Specifically, the controller has a preset oil return condition. After obtaining the operating parameters, the operating parameters will be compared with the oil return condition to determine whether it is necessary to enter the oil return operation mode. When the multi-split system meets the oil return condition, the multi-split system is controlled to enter the oil return operation mode.

[0047] Furthermore, step S110 includes: Get the operating frequency of the compressor; Gets the running time of the multi-connection system when the running frequency is less than the frequency threshold.

[0048] Specifically, by obtaining the operating frequency of the compressor, and when the operating frequency of the compressor is less than the frequency threshold (the compressor is in low-frequency operation at this time), the accumulated oil return time (also known as the operating time of the multi-split system when the operating frequency of the compressor is less than the frequency threshold) is accumulated. By obtaining the operating frequency and the accumulated oil return time, the operating status of the multi-split system is monitored from multiple angles, so that the timing of whether the multi-split system needs oil return can be better judged, a better oil return effect can be ensured, and the impact on the normal use time period of the multi-split system can be minimized. The oil return conditions are set by multiple operating parameters, making the oil return conditions more reasonable and the oil return effect better.

[0049] Preferably, the value of the frequency threshold is determined according to factory settings or user requirements, and the frequency threshold can be selected as 50% of the maximum operating frequency of the compressor; in the present application, the preferred value of the frequency threshold is 55HZ.

[0050] Furthermore, the oil return condition is: the operating time is greater than or equal to a preset time.

[0051] Specifically, the oil return condition can be pre-implanted into the controller, and in different operating modes, the specific standard of the oil return condition will be adjusted accordingly.

[0052] Preferably, the value of the preset duration is determined according to factory settings or user requirements.

[0053] For example, during the operation of the multi-split system, the pressure sensor detects the pressure in real time. At this time, the detected pressure value is the first pressure value. When the compressor is running at a low frequency, the accumulated oil return time t continues to accumulate. When the accumulated oil return time t reaches the preset time of the program, the multi-split system performs oil return operation. At this time, the pressure value of the pressure sensor is detected. ,like , a signal is sent to start the pressurizing device connected between the internal and external units to increase the pressure and flow rate; the pressure sensor reading at this time is controlled During the oil return operation, the compressor frequency increases from the original 50% below the full frequency (that is, the frequency threshold) to a fixed value above 50% of the full frequency. This fixed value is the frequency preset value, which is set according to the program value. Different refrigerants or unit brands have different fixed values.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-connection system, characterized in that: The multi-connection system comprises: A refrigerant circulation pipeline (100), a compressor (110), a first heat exchanger (121), and a second heat exchanger (122), wherein the compressor (110), the first heat exchanger (121), and the second heat exchanger (122) are connected via the refrigerant circulation pipeline (100); A pressure sensor (101), the pressure sensor (101) being arranged on the refrigerant circulation pipeline (100), and the pressure sensor (101) being arranged between the first heat exchanger (121) and the second heat exchanger (122); A pressurizing device (102), wherein the pressurizing device (102) is disposed on the refrigerant circulation pipeline (100), and the pressurizing device (102) is disposed between the pressure sensor (101) and the second heat exchanger (122).

2. A method for controlling oil return in a multi-connected system, the method for controlling oil return is applied to The multi-connection system according to claim 1, characterized in that: The oil return control method comprises: After the multi-connected system is running, detecting whether the multi-connected system enters an oil return operation mode; When the multi-connection system enters the oil return operation mode, obtaining a first pressure value of the pressure sensor; Controlling the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate; Wherein, the operating parameters include: the operating state of the pressurizing device and the operating frequency of the compressor.

3. The oil return control method according to claim 2, characterized in that: The step of controlling the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate includes: When the first pressure value is less than the preset pressure value, controlling the pressurizing device to start operating and controlling the operating frequency to be a preset frequency value to increase the refrigerant flow rate; The first pressure value is monitored in real time and updated.

4. The oil return control method according to claim 3, characterized in that: After the first pressure value is monitored in real time and the first pressure value is updated, the oil return control method further includes: Determining the magnitude of the first pressure value and the preset pressure value; When the first pressure value reaches the preset pressure value, controlling the pressurizing device to stop running; Circularly executing and detecting whether the multi-connection system enters the oil return operation mode; cyclically executing, when the multi-connected system enters the oil return operation mode, obtaining a first pressure value of the pressure sensor; The cycle executes the control of the operating parameters of the multi-split system according to the first pressure value and the preset pressure value to control the refrigerant flow rate.

5. The oil return control method according to any one of claims 2 to 4, characterized in that: The oil return control method further includes: Obtaining an installation height difference between the first heat exchanger and the second heat exchanger; Obtaining a refrigerant density of the refrigerant; The preset pressure value is obtained according to the installation height and the refrigerant density.

6. The oil return control method according to claim 2, characterized in that: After the multi-connected system is running, detecting whether the multi-connected system enters the oil return operation mode includes: After the multi-connection system is running, obtaining the operating parameters of the multi-connection system; Determining whether the multi-connection system meets the oil return condition according to the operating parameters; When the multi-split system meets the oil return condition, the multi-split system is controlled to enter the oil return operation mode.

7. The oil return control method according to claim 6, characterized in that: After the multi-connection system is running, obtaining the operating parameters of the multi-connection system includes: Obtaining the operating frequency of the compressor; The operating time of the multi-connection system is obtained when the operating frequency is less than a frequency threshold.

8. The oil return control method according to claim 7, characterized in that: The oil return condition is: the operating time is greater than or equal to a preset time.

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