Air conditioner outdoor unit multi-connected system, control method and air conditioner

Abstract

The application relates to the air conditioning technical field, and provides an air conditioner outdoor unit multi-connected system, a control method and an air conditioner, the air conditioner outdoor unit multi-connected system comprises an oil separator, a first compressor and at least one second compressor, the first compressor is provided with a heating belt, an exhaust port of the first compressor is connected with an inlet of the oil separator, a suction port of the first compressor is connected with an oil return outlet of the oil separator through a first oil return pipeline, a first oil return control valve is arranged in the first oil return pipeline; an oil discharge port of the second compressor is connected with an oil inlet of the oil separator through an oil discharge pipeline, an oil discharge control valve is arranged in the oil discharge pipeline; and the first compressor is connected with the second compressor through an oil equalization pipeline, an oil equalization control valve is arranged in the oil equalization pipeline. The application can shorten the heating starting time length of the compressor during heating, realizes the purposes of rapid oil return and rapid heating of oil temperature, and can reduce the system energy consumption, and has the energy-saving effect.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to a multi-split outdoor unit system, control method, and air conditioner. Background Technology

[0002] Currently, when multi-split air conditioning systems with at least two compressors are turned on for heating in low temperatures, the heating start-up is slow due to the low outer ring temperature. It often requires heating the heating belt of each compressor to start each compressor in order to ensure that the viscosity of the lubricating oil in the compressor meets the requirements for stable operation. However, this can easily lead to higher energy consumption and longer start-up time for the entire system. The indoor air conditioning unit cannot output enough heat for a long time, resulting in a poor user experience. Summary of the Invention

[0003] This invention provides a multi-split outdoor unit system, control method, and air conditioner, which can shorten the compressor's heating start-up time during heating, achieve rapid oil return and rapid oil temperature heating, and reduce system energy consumption, thus achieving energy-saving effects.

[0004] This invention provides a multi-split outdoor unit system for air conditioning, comprising:

[0005] Oil separator;

[0006] The first compressor is equipped with a heating belt for heating the oil in the first compressor; the exhaust port of the first compressor is connected to the inlet of the oil separator, and the suction port of the first compressor is connected to the return oil outlet of the oil separator via a first return oil pipeline, and a first return oil control valve is provided in the first return oil pipeline.

[0007] At least one second compressor, the oil discharge port of the second compressor is connected to the oil inlet of the oil separator via an oil discharge pipeline, and an oil discharge control valve is provided in the oil discharge pipeline;

[0008] Furthermore, the first compressor is connected to the second compressor via an oil equalization pipeline, and the oil equalization pipeline is equipped with an oil equalization control valve for controlling the oil equalization between the first compressor and the second compressor, so as to supply the hot oil of the first compressor to the second compressor.

[0009] According to the present invention, in a multi-split outdoor unit air conditioning system, the exhaust port of the second compressor is connected to the inlet of the oil separator, the suction port of the second compressor is connected to the oil return outlet of the oil separator via a second oil return pipeline, and a second oil return control valve is provided in the second oil return pipeline.

[0010] According to the present invention, a multi-split outdoor unit air conditioning system further includes:

[0011] Four-way valve;

[0012] A gas-liquid separator, wherein the inlet of the gas-liquid separator is connected to the four-way valve, and the outlet of the gas-liquid separator is connected to the suction ports of the first compressor and the second compressor respectively;

[0013] Furthermore, the refrigerant outlet of the oil separator is connected to the four-way valve.

[0014] According to the present invention, an outdoor multi-split air conditioning system is provided, wherein the first compressor and the second compressor are equipped with an oil temperature sensor and an oil quantity sensor.

[0015] The present invention also provides a control method for the above-mentioned multi-split outdoor unit system of an air conditioner, comprising:

[0016] When the air conditioner is in heating mode, obtain the load of the indoor unit.

[0017] When the load of the indoor air conditioning unit reaches the target preset load, the number of second compressors in operation is determined based on the load of the indoor air conditioning unit, and a multi-split control strategy is executed:

[0018] The heating element of the first compressor is turned on to heat up, and after the oil temperature of the first compressor reaches the set temperature, the first compressor is started to run.

[0019] The oil equalization control valve corresponding to the second compressor that is controlled and determined to be in operation is opened to supply hot oil from the first compressor to the second compressor that is determined to be in operation.

[0020] The oil temperature and oil quantity of the second compressor in operation were determined by detection;

[0021] The start-up of the second compressor is controlled based on the determined oil temperature and oil quantity of the second compressor in operation.

[0022] According to a control method for a multi-split outdoor unit air conditioning system provided by the present invention, the step of controlling the start-up of the determined second compressor based on the determined oil temperature and oil quantity of the second compressor includes:

[0023] If it is determined that the oil temperature of the second compressor in operation has reached the set temperature and the oil quantity has reached the second set oil quantity, control the second compressor in operation to start running.

[0024] If it is determined that the oil temperature of the second compressor in operation has reached the set temperature and the oil quantity is greater than the second set oil quantity, control the second compressor in operation to unload oil until the second set oil quantity is reached, and then control the second compressor in operation to start running.

[0025] If the oil temperature of the second compressor is determined to be lower than the set temperature, control the first compressor to return oil and control the second compressor to unload oil until the oil temperature of the second compressor reaches the set temperature and the oil quantity reaches the second set oil quantity, then control the second compressor to start running.

[0026] According to the control method of a multi-split outdoor unit air conditioning system provided by the present invention, during the process of supplying hot oil from the first compressor to the second compressor which is determined to be in operation, the method further includes the following steps:

[0027] If the oil level in the first compressor is less than the first set oil level, control the first compressor to return oil.

[0028] According to a control method for a multi-split outdoor unit air conditioning system provided by the present invention, the step of determining the number of operating second compressors based on the load of the indoor unit air conditioning unit includes:

[0029] The number of second compressors in operation is proportional to the load of the indoor unit of the air conditioner.

[0030] The control method for a multi-split outdoor unit system of an air conditioner provided by the present invention further includes:

[0031] If the load on the indoor unit of the air conditioner does not reach the target preset load, a single-unit control strategy is executed: the heating belt of the first compressor is turned on to heat up, and after the oil temperature of the first compressor reaches the set temperature, the first compressor is started to run.

[0032] The present invention also provides an air conditioner, including: the above-mentioned multi-split outdoor unit system of an air conditioner, or, when performing control, using the above-mentioned control method for the multi-split outdoor unit system of an air conditioner.

[0033] The multi-split outdoor unit air conditioning system, control method, and air conditioner provided by this invention, by setting up an oil equalization pipeline between the first and second compressors, and utilizing the high-temperature hot oil supplied to the second compressor after the first compressor reaches its operating temperature, heats the oil in the second compressor, achieving rapid oil temperature heating and thus shortening the heating start-up time of the second compressor. Furthermore, the entire system only requires one heating element to be activated, effectively reducing system energy consumption. During the oil supply process to the first compressor, oil return can be achieved through a first oil return control valve, ensuring normal oil levels in the first compressor and guaranteeing its normal operation. Similarly, an oil unloading control valve can ensure normal oil levels in the second compressor, guaranteeing its normal start-up and operation. Therefore, this invention can shorten the compressor heating start-up time during heating, achieve rapid oil return and rapid oil temperature heating, and reduce system energy consumption, resulting in energy savings and effectively improving the user experience. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the multi-split outdoor unit air conditioning system provided by the present invention;

[0036] Figure 2 This is one of the schematic diagrams of the control method for a multi-split outdoor unit system of an air conditioner provided by the present invention;

[0037] Figure 3 This is the second schematic diagram of the control method for a multi-split outdoor unit system of an air conditioner provided by the present invention;

[0038] Figure 4 This is a schematic diagram of the structure of the air conditioner provided by the present invention;

[0039] Figure 5 This is a schematic diagram of the heating principle of the air conditioner provided by the present invention.

[0040] Figure label:

[0041] 1: Oil separator; 2: First compressor; 3: Second compressor;

[0042] 4: First exhaust pipe; 5: First return oil pipe; 6: First return oil control valve;

[0043] 7: Oil unloading pipeline; 8: Oil unloading control valve; 9: Oil equalization pipeline; 10: Oil equalization control valve;

[0044] 11: Second exhaust pipe; 12: Second return oil pipe; 13: Second return oil control valve;

[0045] 14: Gas-liquid separator; 15: Four-way valve; 16: Throttling device; 17: Condenser;

[0046] 18: Evaporator. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] In the description of the embodiments of the present invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] The following is combined with Figures 1-5 The present invention describes an air conditioning outdoor unit multi-split system, control method, and air conditioner.

[0052] According to an embodiment of the first aspect of the present invention, referring to Figure 1 As shown, the present invention provides a multi-split outdoor unit air conditioning system, which mainly includes: an oil separator 1, a first compressor 2 and at least one second compressor 3.

[0053] Among them, the oil separator 1 is mainly used to separate the refrigerant and lubricating oil discharged from the first compressor 2 and the second compressor 3.

[0054] The first compressor 2 is equipped with a heating belt, which is used to heat the oil of the first compressor 2, i.e., the lubricating oil. After the lubricating oil reaches the set temperature for starting, the first compressor 2 starts and begins to increase its frequency until it is running normally. Furthermore, the exhaust port of the first compressor 2 is connected to the inlet of the oil separator 1 through the first exhaust pipe 4, and the suction port of the first compressor 2 is connected to the return oil outlet of the oil separator 1 through the first return oil pipe 5. The first return oil pipe 5 is equipped with a first return oil control valve 6.

[0055] Specifically, after the first compressor 2 starts running, the refrigerant and lubricating oil discharged from the first compressor 2 enter the oil separator 1 for separation. The separated lubricating oil can return to the first compressor 2 through the first return oil pipeline 5, and the amount of oil returned by the first compressor 2 can be controlled by controlling the opening of the first return oil control valve 6.

[0056] Each second compressor 3 has its oil discharge port connected to the oil inlet of the oil separator 1 via an oil discharge pipeline 7, and the oil discharge pipeline 7 is equipped with an oil discharge control valve 8.

[0057] It is understandable that the first compressor 2 and the second compressor 3 store a certain amount of lubricating oil inside. During the process of the first compressor 2 supplying hot oil to the second compressor 3, the oil volume of the second compressor 3 increases. When the oil volume exceeds the second set oil volume, the oil unloading control valve 8 can be opened to unload the oil of the second compressor 3 into the oil separator 1. On the one hand, this can ensure that the oil volume in the second compressor 3 is normal, so that the second compressor 3 can start normally. On the other hand, it can recover the compressor oil volume so that it can be reused by the first compressor 2 and the second compressor 3 in the future.

[0058] Furthermore, the first compressor 2 is connected to at least one second compressor 3 via an oil equalization pipeline 9. An oil equalization control valve 10 is provided in the oil equalization pipeline 9. The oil equalization control valve 10 is used to control the oil equalization between the first compressor 2 and the second compressor 3, so as to supply the hot oil of the first compressor 2 to the second compressor 3.

[0059] Specifically, when the second compressor 3 needs to be started, the hot oil from the first compressor 2 can be supplied to the second compressor 3 by controlling the oil equalization control valve 10 to heat the oil inside the second compressor 3 so that the second compressor 3 can start quickly.

[0060] It is understandable that, compared with traditional heating belt heating, the oil temperature of the first compressor 2 after starting operation is higher than the oil temperature when heated by heating belt before starting, and the heating speed of the present invention is faster, thereby effectively shortening the start-up heating time of the second compressor 3.

[0061] The multi-split outdoor unit air conditioning system provided in this embodiment of the invention, by setting up an oil equalization pipeline 9 between the first compressor 2 and the second compressor 3, and utilizing the high-temperature hot oil supplied to the second compressor 3 after the first compressor 2 reaches its starting temperature, heats the oil in the second compressor 3, achieving the purpose of rapidly heating the oil temperature, thereby shortening the heating start-up time of the second compressor 3. Furthermore, the entire system only requires one heating element to be activated, effectively reducing system energy consumption. During the oil supply process to the first compressor 2, oil return can be achieved through the first oil return control valve 6, ensuring the normal oil level in the first compressor 2 and guaranteeing its normal operation. Similarly, the oil unloading control valve 8 ensures the normal oil level in the second compressor 3, guaranteeing its normal start-up and operation. Therefore, this invention can shorten the heating start-up time of the compressor during heating, achieve rapid oil return and rapid oil temperature heating, and reduce system energy consumption, resulting in energy savings and effectively improving the user experience.

[0062] According to one embodiment of the present invention, referring to Figure 1 As shown, the exhaust port of the second compressor 3 is connected to the inlet of the oil separator 1 via the second exhaust pipe 11, and the suction port of the second compressor 3 is connected to the oil return outlet of the oil separator 1 via the second oil return pipe 12. The second oil return pipe 12 is equipped with a second oil return control valve 13.

[0063] Specifically, after the second compressor 3 starts running, the refrigerant and lubricating oil discharged from the second compressor 3 enter the oil separator 1 for separation. The separated lubricating oil can return to the second compressor 3 through the second return oil pipeline 12. The amount of oil returned by the second compressor 3 can be controlled by controlling the opening of the second return oil control valve 13 to ensure normal oil quantity and thus ensure the normal operation of the second compressor 3.

[0064] According to one embodiment of the present invention, referring to Figure 1 As shown, the multi-split air conditioning outdoor unit system also includes: a gas-liquid separator 14 and a four-way valve 15. The inlet of the gas-liquid separator 14 is connected to the four-way valve 15, and the outlet of the gas-liquid separator 14 is connected to the suction ports of the first compressor 2 and the second compressor 3 respectively; and the refrigerant outlet of the oil separator 1 is connected to the four-way valve 15.

[0065] In addition, refer to Figure 4 As shown, the multi-split outdoor unit system of the air conditioner also includes a throttling device 16 and a condenser 17. The four ports of the four-way valve 15 are respectively connected to the refrigerant outlet of the oil separator 1, the inlet of the gas-liquid separator 14, the condenser 17, and the evaporator 18 of the indoor unit of the air conditioner. The condenser 17 is connected to the evaporator 18, and the throttling device 16 is connected between the condenser 17 and the evaporator 18.

[0066] Specifically, when the air conditioner is in heating mode, the refrigerant separated by the oil separator 1 is sent to the evaporator 18 of the indoor unit of the air conditioner through the four-way valve 15 to release heat. Then, after being throttled by the throttling device 16, it flows through the condenser 17 to absorb heat. Then, it flows into the gas-liquid separator 14 through the four-way valve 15 for gas-liquid separation. The separated gaseous refrigerant is sent to the first compressor 2 and the second compressor 3.

[0067] According to one embodiment of the present invention, the first compressor 2 and the second compressor 3 are provided with an oil temperature sensor and an oil quantity sensor. The oil temperature sensor is used to detect the oil temperature inside the first compressor 2 and the second compressor 3, and the oil quantity sensor is used to detect the oil quantity inside the first compressor 2 and the second compressor 3.

[0068] According to one embodiment of the present invention, the return oil control valve, the unloading oil control valve 8, and the equalization oil control valve 10 are all solenoid valves, which facilitates control.

[0069] The control method of the multi-split air conditioner outdoor unit system provided by the present invention is described below. The control method of the multi-split air conditioner outdoor unit system described below can be referred to in correspondence with the multi-split air conditioner outdoor unit system described above.

[0070] According to an embodiment of the second aspect of the present invention, referring to Figure 2 As shown, the present invention also provides a control method for a multi-split outdoor unit air conditioning system according to the above embodiments, which mainly includes the following steps:

[0071] S100. When the air conditioner is in heating mode, obtain the load of the indoor unit of the air conditioner;

[0072] S200: When the load of the indoor unit of the air conditioner reaches the target preset load, determine the number of second compressors 3 in operation based on the load of the indoor unit of the air conditioner, and execute the multi-split control strategy:

[0073] S201. Control the heating belt of the first compressor 2 to turn on and heat it. After the oil temperature of the first compressor 2 reaches the set temperature, control the first compressor 2 to start running.

[0074] S202, the oil equalization control valve 10 corresponding to the second compressor 3 that controls and determines the operation is opened to supply hot oil from the first compressor 2 to the second compressor 3 that determines the operation;

[0075] S203. Detect and determine the oil temperature and oil quantity of the operating second compressor 3;

[0076] S204. Based on the determined oil temperature and oil quantity of the second compressor 3, control the start-up of the second compressor 3.

[0077] The control method for a multi-split outdoor unit air conditioning system provided by the present invention utilizes the high-temperature hot oil supplied to the second compressor 3 after the first compressor 2 reaches its starting temperature to heat the oil in the second compressor 3, thereby achieving the purpose of rapidly heating the oil temperature, thus shortening the heating start-up time of the second compressor 3. Furthermore, only one heating element needs to be activated, which can effectively reduce system energy consumption and has an energy-saving effect, thereby effectively improving the user experience.

[0078] According to one embodiment of the present invention, referring to Figure 3 As shown, the steps for controlling the start-up of the second compressor 3, which is determined to be in operation, based on the determined oil temperature and oil quantity, include:

[0079] S2041. If it is determined that the oil temperature of the second compressor 3 in operation has reached the set temperature and the oil quantity has reached the second set oil quantity, control the second compressor 3 in operation to start running.

[0080] S2042. If the oil temperature of the second compressor 3 is determined to reach the set temperature and the oil quantity is greater than the second set oil quantity, control the second compressor 3 to unload oil until the second set oil quantity is reached, and control the second compressor 3 to start running.

[0081] S2043. If the oil temperature of the second compressor 3 is determined to be lower than the set temperature, control the first compressor 2 to return oil and control the second compressor 3 to unload oil until the oil temperature of the second compressor 3 reaches the set temperature and the oil quantity reaches the second set oil quantity, then control the second compressor 3 to start running.

[0082] Specifically, when controlling the start of the second compressor 3, the oil quantity and oil temperature conditions need to be met. During the process of the first compressor 2 continuously supplying hot oil to the second compressor 3, the oil temperature and oil quantity inside the second compressor 3 both increase. When the oil temperature and oil quantity reach the set oil temperature and the second set oil quantity for start-up, the second compressor 3 can be controlled to start up and increase the frequency until it is in normal operation.

[0083] Furthermore, since the second compressor 3 itself stores a certain amount of lubricating oil, when the first compressor 2 supplies hot oil to the second compressor 3, the oil volume of the second compressor 3 increases, causing its oil volume to exceed the second set oil volume. At this time, the oil unloading control valve 8 can be opened to unload the oil of the second compressor 3 into the oil separator 1. On the one hand, this can ensure that the oil volume in the second compressor 3 is normal, so that the second compressor 3 can start normally, increase frequency until normal operation; on the other hand, it can recover the compressor oil volume so as to facilitate the subsequent oil return utilization of the first compressor 2 and the second compressor 3.

[0084] Furthermore, during the continuous supply of hot oil from the first compressor 2 to the second compressor 3, if the oil temperature of the second compressor 3 is still lower than the set temperature, the second compressor 3 is controlled to unload oil, and the oil with a lower internal temperature is unloaded into the oil separator 1 to receive the high-temperature hot oil from the first compressor 2. At the same time, in order to ensure that the oil quantity inside the first compressor 2 is normal, the first oil return control valve 6 corresponding to the first compressor 2 is controlled to open to return oil, thereby realizing the rapid oil change operation of the second compressor 3. When the oil quantity and oil temperature of the second compressor 3 both reach the set conditions, the second compressor 3 is turned on again, and the frequency is increased until normal operation is achieved.

[0085] Therefore, by performing an oil change operation on the second compressor 3 while simultaneously performing an oil return operation on the first compressor 2, the embodiments of the present invention can ensure the normal operation of the first compressor 2, and can shorten the heating and start-up time of the second compressor 3, improve its start-up speed, and ensure its normal start-up and operation.

[0086] According to one embodiment of the present invention, in the process of supplying hot oil from the first compressor 2 to the second compressor 3 which is determined to be in operation, the step further includes: if the oil quantity of the first compressor 2 is less than the first set oil quantity, controlling the first compressor 2 to return oil.

[0087] Specifically, during the oil supply process of the first compressor 2, oil can be returned through the first oil return control valve 6 to ensure that the oil quantity of the first compressor 2 is normal, thereby ensuring the normal operation of the first compressor 2.

[0088] According to one embodiment of the present invention, the step of determining the number of second compressors 3 in operation based on the load of the air conditioner indoor unit includes: the number of second compressors 3 in operation is proportional to the load of the air conditioner indoor unit, that is, the greater the load of the air conditioner indoor unit, the more second compressors 3 in operation.

[0089] According to one embodiment of the present invention, referring to Figure 2 As shown, the control method for the multi-split outdoor unit system of the air conditioner of the present invention further includes the following steps:

[0090] S300. When the load of the indoor unit of the air conditioner does not reach the target preset load, execute the single-unit control strategy: control the heating belt of the first compressor 2 to turn on and heat it. After the oil temperature of the first compressor 2 reaches the set temperature, control the first compressor 2 to start running.

[0091] Therefore, the control method for the multi-split outdoor unit system of the air conditioner provided in this embodiment of the invention can match the control strategy of the number of compressors running according to the load of the indoor unit of the air conditioner, thereby ensuring the heat exchange effect in the room and improving the user experience.

[0092] According to an embodiment of the third aspect of the present invention, referring to Figure 4 and Figure 5As shown, the present invention also provides an air conditioner, mainly comprising: an indoor air conditioner having an evaporator 18 and an outdoor multi-split air conditioner system of the above embodiments, or, when performing control, employing the control method of the outdoor multi-split air conditioner system of the above embodiments.

[0093] The heating principle of the air conditioner of the present invention is described below with reference to a specific example, such as... Figure 5 As shown, a second compressor 3 is provided, and the flow direction of refrigerant and lubricating oil is shown by the arrow in the figure.

[0094] The heating principle of the air conditioner in this embodiment of the invention generally includes:

[0095] When the indoor unit of the air conditioner is under low load, the entire system executes a single-unit control strategy, that is, controls the first compressor 2 to start and run alone;

[0096] When the indoor unit of the air conditioner is under heavy load and the second compressor 3 needs to be turned on, the entire system executes a dual-unit control strategy. At this time, the heating belt of the first compressor 2 is activated to heat up the oil temperature of the first compressor 2 until it reaches the set temperature. Then, the first compressor 2 is started and its frequency is increased until it is running normally. Then, the corresponding oil equalization control valve 10 of the second compressor 3 is opened to supply the hot oil from the first compressor 2 to the second compressor 3, and the oil temperature and oil quantity of the second compressor 3 are detected.

[0097] (1) If the oil temperature of the second compressor 3 reaches the set temperature and the oil quantity reaches the second set oil quantity, the second compressor 3, which is determined to be running, starts up and increases the frequency until it is running normally.

[0098] (2) If the oil temperature of the second compressor 3 reaches the set temperature and the oil quantity is greater than the second set oil quantity, open the oil unloading control valve 8 corresponding to the second compressor 3 to unload the oil. When the oil quantity drops to the second set oil quantity, control the second compressor 3 to start and increase the frequency until it is in normal operation.

[0099] (3) If the oil temperature of the second compressor 3 is lower than the set temperature, control the first oil return control valve 6 corresponding to the first compressor 2 to open for oil return, and open the oil unloading control valve 8 corresponding to the second compressor 3 to unload oil until the oil temperature of the second compressor 3 reaches the set temperature and the oil quantity reaches the second set oil quantity, control the second compressor 3 to start, increase the frequency until normal operation.

[0100] During the operation of the first compressor 2 and the second compressor 3, lubricating oil and refrigerant are discharged into the oil separator 1. The separated lubricating oil can be returned to the first compressor 2 and the second compressor 3 according to the oil return requirements. The separated refrigerant is sent to the evaporator 18 of the air conditioner indoor unit through the four-way valve 15 to release heat. Then, after being throttled by the throttling device 16, it flows through the condenser 17 to absorb heat. Then, it flows into the gas-liquid separator 14 through the four-way valve 15 for gas-liquid separation. The separated gaseous refrigerant is sent to the first compressor 2 and the second compressor 3.

[0101] Therefore, the air conditioner of this invention can shorten the heating start-up time of the compressor during heating, achieve the purpose of rapid oil return and rapid oil temperature heating, meet the indoor heat exchange requirements, and reduce system energy consumption, thus achieving energy-saving effect and effectively improving the user experience.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-split outdoor unit system for air conditioning, characterized in that, include: Oil separator; The first compressor is equipped with a heating belt for heating the oil in the first compressor; The exhaust port of the first compressor is connected to the inlet of the oil separator, and the suction port of the first compressor is connected to the oil return outlet of the oil separator via the first oil return pipeline. The first oil return pipeline is equipped with a first oil return control valve. At least one second compressor, the oil discharge port of the second compressor is connected to the oil inlet of the oil separator via an oil discharge pipeline, and an oil discharge control valve is provided in the oil discharge pipeline; Furthermore, the first compressor is connected to the second compressor via an oil equalization pipeline, and the oil equalization pipeline is equipped with an oil equalization control valve for controlling the oil equalization between the first compressor and the second compressor, so as to supply the hot oil of the first compressor to the second compressor. When the air conditioner is in heating mode, the multi-split outdoor unit system only activates one of the heating belts of the first compressor.

2. The multi-split outdoor unit air conditioning system according to claim 1, characterized in that, The exhaust port of the second compressor is connected to the inlet of the oil separator, and the suction port of the second compressor is connected to the return oil outlet of the oil separator via the second return oil pipeline. The second return oil pipeline is equipped with a second return oil control valve.

3. The multi-split outdoor unit air conditioning system according to claim 2, characterized in that, Also includes: Four-way valve; A gas-liquid separator, wherein the inlet of the gas-liquid separator is connected to the four-way valve, and the outlet of the gas-liquid separator is connected to the suction ports of the first compressor and the second compressor respectively; Furthermore, the refrigerant outlet of the oil separator is connected to the four-way valve.

4. The multi-split outdoor unit air conditioning system according to claim 1, characterized in that, The first compressor and the second compressor are equipped with an oil temperature sensor and an oil quantity sensor.

5. A control method for a multi-split outdoor unit system of an air conditioner according to any one of claims 1-4, characterized in that, include: When the air conditioner is in heating mode, obtain the load of the indoor unit. When the load of the indoor air conditioning unit reaches the target preset load, the number of second compressors in operation is determined based on the load of the indoor air conditioning unit, and a multi-split control strategy is executed: The heating element of the first compressor is turned on to heat up, and after the oil temperature of the first compressor reaches the set temperature, the first compressor is started to run. The oil equalization control valve corresponding to the second compressor that is controlled and determined to be in operation is opened to supply hot oil from the first compressor to the second compressor that is determined to be in operation. The oil temperature and oil quantity of the second compressor in operation were determined by detection; The start-up of the second compressor is controlled based on the determined oil temperature and oil quantity of the second compressor in operation.

6. The control method for a multi-split outdoor unit system of an air conditioner according to claim 5, characterized in that, The steps for controlling the start-up of the second compressor, based on the determined oil temperature and oil quantity, include: If it is determined that the oil temperature of the second compressor in operation has reached the set temperature and the oil quantity has reached the second set oil quantity, control the second compressor in operation to start running. If it is determined that the oil temperature of the second compressor in operation has reached the set temperature and the oil quantity is greater than the second set oil quantity, control the second compressor in operation to unload oil until the second set oil quantity is reached, and then control the second compressor in operation to start running. If the oil temperature of the second compressor is determined to be lower than the set temperature, control the first compressor to return oil and control the second compressor to unload oil until the oil temperature of the second compressor reaches the set temperature and the oil quantity reaches the second set oil quantity, then control the second compressor to start running.

7. The control method for a multi-split outdoor unit system of an air conditioner according to claim 5, characterized in that, The process of supplying hot oil from the first compressor to the second compressor, which is already in operation, also includes the following steps: If the oil level in the first compressor is less than the first set oil level, control the first compressor to return oil.

8. The control method for a multi-split outdoor unit system of an air conditioner according to claim 5, characterized in that, The step of determining the number of second compressors in operation based on the load of the indoor air conditioning unit includes: The number of second compressors in operation is proportional to the load of the indoor unit of the air conditioner.

9. The control method for a multi-split outdoor unit system of an air conditioner according to claim 5, characterized in that, Also includes: If the load on the indoor unit of the air conditioner does not reach the target preset load, a single-unit control strategy is executed: the heating belt of the first compressor is turned on to heat up, and after the oil temperature of the first compressor reaches the set temperature, the first compressor is started to run.

10. An air conditioner, characterized in that, include: The air conditioning outdoor unit multi-split system according to any one of claims 1-4, or when performing control, the control method of the air conditioning outdoor unit multi-split system according to any one of claims 5-9.

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