Control method and control device of compressor unit

Abstract

According to the control method and device for the compressor unit, the oil level of the first compressor and the oil level of the second compressor can be adjusted without additionally arranging an oil return pipeline. The first aspect of the invention provides a control method of a compressor unit, the compressor unit is provided with a first compressor and a second compressor, and the first compressor and the second compressor are communicated through a gas balance pipe and an oil balance pipe. Wherein the compressor unit has a conventional working step and an oil level adjusting step which are alternately operated, and in the oil level adjusting step, the compressor unit changes the rotating speed of the first compressor and / or the second compressor and adjusts the oil levels of the first compressor and the second compressor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressors, in particular to a control method and a control device of a compressor unit. BACKGROUND

[0002] Currently, the compressor unit composed of two parallel compressors generally has the problem of difficult adjustment of the oil level of the compressors. After the two compressors are operated simultaneously for a period of time, the oil level in the two compressors may be unbalanced, or after one compressor is operated alone for a period of time, the oil level in the compressor may decrease, causing the two or one compressor to be in an oil loss state and affecting the normal operation of the compressor unit.

[0003] To this end, patent CN101017039A proposes a double-compressor air conditioner oil balancing device, a gas balancing pipe and an oil balancing pipe are connected between two parallel compressors, the total exhaust pipe side of the compressor is connected to an oil separator, and the oil level adjustment between the two compressors is realized based on the oil return pipeline composed of the oil separator, the condenser, the evaporator, and the electromagnetic valve, but the oil return pipeline device in patent CN101017039A is complex and has high improvement cost. SUMMARY

[0004] The present application aims to provide a control method and a control device of a compressor unit to at least solve or alleviate the problems existing in the prior art.

[0005] The first aspect of the present application provides a control method of a compressor unit, the compressor unit having a first compressor and a second compressor, the first compressor and the second compressor being communicated through a gas balancing pipe and an oil balancing pipe. At least one working mode of the compressor unit has a conventional working step and an oil level adjustment step which are alternately operated, in the oil level adjustment step, the compressor unit changes the rotating speed of the first compressor and / or the second compressor and continuously operates for a specified time to adjust the oil level of the first compressor and the second compressor.

[0006] In the control method of the compressor unit of the optional technical solution, the continuous operation specified time of the oil level adjustment step is 0-10 min.

[0007] In the control method of the compressor unit of the optional technical solution, the continuous operation specified time of the conventional working step is 0.5-2 h.

[0008] In the control method of the compressor unit of the optional technical solution, the first compressor of the compressor unit is a variable speed compressor, and the second compressor of the compressor unit is a constant speed compressor.

[0009] In the control method of the compressor unit of the optional technical solution, the outlet of the second compressor is further provided with a one-way valve.

[0010] In the control method of the compressor unit of the alternative solution, if the compressor unit operates in the heating condition in the normal working step, and both the first compressor and the second compressor operate, then in the oil level adjustment step, the rotating speed of the first compressor is set between the upper limit rotating speed and the lower limit rotating speed of the first compressor.

[0011] If the compressor unit operates in the refrigeration condition in the normal working step, and both the first compressor and the second compressor operate, then in the oil level adjustment step, the rotating speed of the first compressor is set equal to the upper limit rotating speed of the first compressor.

[0012] In the control method of the compressor unit of the alternative solution, if the compressor unit operates in the heating condition in the normal working step, and the first compressor operates and the second compressor stops, then in the oil level adjustment step, the rotating speed of the first compressor is adjusted to between the upper limit rotating speed and the lower limit rotating speed of the first compressor.

[0013] In the control method of the compressor unit of the alternative solution, if the compressor unit operates in the refrigeration condition in the normal working step, and the first compressor operates and the second compressor stops, then in the oil level adjustment step, the second compressor is opened and the first compressor is adjusted to be lower than the upper limit rotating speed of the first compressor.

[0014] In the control method of the compressor unit of the alternative solution, if the compressor unit operates in the refrigeration condition in the normal working step, and the first compressor operates and the second compressor stops, then before the second compressor is opened, the rotating speed of the first compressor is reduced.

[0015] The second aspect of the present application provides a control device of a compressor unit, the compressor unit having a first compressor and a second compressor, the first compressor and the second compressor being communicated through a gas balance pipe and an oil balance pipe. The control device comprises a normal working unit and an oil level adjustment unit which are alternately operated, the oil level adjustment unit generating an instruction to change the rotating speed of the first compressor and / or the second compressor and continuously operate for a specified time according to the normal working step, so as to adjust the oil level of the first compressor and the second compressor.

[0016] In the control device of the compressor unit of the alternative solution, the first compressor of the compressor unit is a variable speed compressor, and the second compressor of the compressor unit is a constant speed compressor.

[0017] According to the control method and the control device of the compressor unit of the present application, the normal operation of the compressor unit is affected very little by the alternately operated oil level adjustment step in the normal working step. Moreover, no additional oil return pipeline is needed, and the oil level of the first compressor and the second compressor can be adjusted only by adjusting the rotating speed of the first compressor and / or the second compressor in the oil level adjustment step, so that the device is simple and can be conveniently improved for the traditional compressor unit. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Fig. 1 shows a hardware structure of a compressor unit to which a control method and a control device provided by some embodiments of the present application are applied.

[0019] Figure 2 Fig. 2 shows another hardware structure of a compressor unit to which a control method and a control device provided by some embodiments of the present application are applied.

[0020] Figure 3 Fig. 3 shows a flowchart of a control method of a compressor unit provided by some embodiments of the present application.

[0021] Figure 4 Fig. 4 shows an optional control method of a compressor unit provided by some embodiments of the present application.

[0022] Figure 5 Fig. 5 shows a schematic diagram of switching of rotational speeds of a first compressor and a second compressor in a control method of a compressor unit in a high-power output mode according to some embodiments of the present application.

[0023] Figure 6 Fig. 6 shows a schematic diagram of switching of rotational speeds of a first compressor and a second compressor in a control method of a compressor unit in a low-power output mode according to some embodiments of the present application.

[0024] Figure 7 Fig. 7 shows a structure of a control device of a compressor unit provided by some embodiments of the present application.

[0025] BRIEF DESCRIPTION OF DRAWINGS

[0026] 100 - compressor unit; 200 - control device;

[0027] 1 - first compressor; 2 - second compressor; 3 - gas balance pipe; 4 - oil balance pipe; 5 - conventional working unit; 6 - oil level adjusting unit; 7 - first electromagnetic valve (one-way valve); 8 - second electromagnetic valve; 9 - balance branch. DETAILED DESCRIPTION

[0028] Some embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0029] Figure 1 Fig. 1 shows a hardware structure of a compressor unit to which a control method and a control device provided by some embodiments of the present application are applied. As shown in Fig. 1, the compressor unit includes a first compressor 1, a second compressor 2, a gas balance pipe 3, an oil balance pipe 4, a conventional working unit 5, an oil level adjusting unit 6, a first electromagnetic valve (one-way valve) 7, a second electromagnetic valve 8, and a balance branch 9. Figure 1As shown, the compressor set 100 includes a first compressor 1 and a second compressor 2, which are connected through a gas balance pipe 3 and an oil balance pipe 4. In a non-operation state of the compressor set 100, the gas pressures in the first compressor 1 and the second compressor 2 are balanced by the gas balance pipe 3, and the oil levels in the first compressor 1 and the second compressor 2 are balanced by the oil balance pipe 4. However, when the first compressor 1 and the second compressor 2 are operated simultaneously or one of the compressors (the first compressor 1 or the second compressor 2) is operated alone, the oil levels in the first compressor 1 and the second compressor 2 may be unbalanced due to a pressure difference between the first compressor 1 and the second compressor 2, or the oil levels in the first compressor 1 and the second compressor 2 may be reduced due to the retention of lubricating oil in the system pipeline and the reduction of oil return of the compressor after a long time of operation, so that at least one of the compressors is in a low oil level state, which affects the normal operation of the compressor set.

[0030] The first compressor 1 and the second compressor 2 may also be two variable speed compressors connected in parallel, or the first compressor 1 and the second compressor 2 may also be one fixed speed compressor and one variable speed compressor connected in parallel. All of the above belong to the protection scope of the present application.

[0031] Hereinafter, the compressor set including one fixed speed compressor (the second compressor 2) and one variable speed compressor (the first compressor 1) is taken as an example for description. The parallel connection of the fixed speed compressor and the variable speed compressor, and the start-stop of the fixed speed compressor can control the range of the output power of the compressor set 100, and the variable speed compressor can further finely adjust the output power of the compressor set 100 in the range, so that the output power of the compressor set 100 can be adjusted more quickly and stably.

[0032] The compressor set 100 may be the compressor set of any refrigeration / heating appliance, which is not limited herein. For example, the compressor set 100 may be used in air conditioners, refrigerators, freezers, etc. Herein, the operation of the compressor set 100 in a high power output mode and a low power output mode is described by taking an air conditioner as an example.

[0033] <High power output mode>

[0034] When the compressor set 100 is in the high power output mode, i.e., the first compressor 1 and the second compressor 2 are both operated, specifically, the second compressor 2 is operated at a rated speed, and the first compressor 1 is operated in a variable speed mode. The first compressor 1 can be operated at a variable speed between an upper limit speed and a lower limit speed according to the requirement of the working condition.

[0035] <Low power output mode>

[0036] When the compressor unit 100 is in low-power output mode, that is, the mode in which the first compressor 1 is operating and the second compressor 2 is stopped. If the compressor unit 100 is used for heating, as described in the high-power output mode, the first compressor 1 can operate at a variable speed between its upper and lower speed limits according to the operating conditions. Because the second compressor 2 is stopped in the low-power output mode, the first compressor 1 can operate at a lower speed. If the compressor unit 100 is used for cooling, the first compressor 1 also adjusts its operation between its corresponding upper and lower speed limits according to the operating conditions, and of course, it can also maintain a constant speed according to the operating conditions.

[0037] According to the compressor unit 100 applicable to the control method and control device of some embodiments of the present application, both the high-power output mode and the low-power output mode can ensure that the total output power of the compressor unit 100 is adjustable, and the range of the total output power of the compressor unit 100 can be quickly adjusted by starting and stopping the second compressor 2.

[0038] In addition, Figure 1 In the compressor unit to which some embodiments of the present application are applicable, the high-pressure ends of the first compressor 1 and the second compressor 2 are connected. In other words, the high-pressure end pipeline of the first compressor 1 and the second compressor 2 is shared. Figure 1 The compressor unit 100 involved in the present application is illustrated in this way, but even if it is a compressor unit in which each compressor operates through an independent high-pressure end, as long as the compressors are connected to each other at the low-pressure end or the return oil pipelines are connected to each other, the present application can be fully applied.

[0039] According to some other optional embodiments, the compressor unit is applicable, such as Figure 2 As shown, the exhaust pipes at the high-pressure ends of the first compressor 1 and the second compressor 2 are connected, and a control valve is provided on the exhaust pipe at the exhaust outlet near the high-pressure end of the second compressor 2. The valve can be any valve body for opening and closing the control pipe. Here, the case where a first solenoid valve 7 (one-way valve) is provided on the exhaust pipe at the exhaust outlet of the high-pressure end of the second compressor 2 is used as an example to illustrate. In the low-power output mode, the first solenoid valve 7 can be closed, thereby preventing the refrigerant from entering the second compressor 2 along with the exhaust flow during the operation of the first compressor 1.

[0040] Furthermore, the suction pipelines of the low-pressure ends of the first compressor 1 and the second compressor 2 are connected. In particular, the suction pipeline of the second compressor 2 also has a balancing branch 9 connected to the exhaust pipeline of the second compressor 2. A second solenoid valve 8 is provided on the balancing branch 9. In high-power output mode, the second solenoid valve 8 can be opened to balance the pressure in the cavities of the first compressor 1 and the second compressor 2.

[0041] Next, based on the above compressor unit 100, the control method and control device of the compressor unit 100 provided by the application are further described in combination with specific embodiments. It should be noted that the compressor unit 100 controlled by the control method and control device of the compressor unit 100 in some embodiments of the application only needs to have two parallel compressors, and is not limited by the above-mentioned fixed-speed compressor, variable-speed compressor, and upper and lower limit parameters of the compressor speed. Even if the compressor unit 100 is not set according to the above parameters, it can also run the control method and control device of at least one compressor unit provided by the application, which all belong to the protection scope of the application.

[0042] First embodiment

[0043] Figure 3 The flowchart of the control method of the compressor unit provided by some embodiments of the application is shown. In combination with Figure 1 and Figure 3 , the control method of the compressor unit of some embodiments of the application is applicable to any compressor unit 100 having two parallel compressors. In the control method of the compressor unit, the normal working step S1 and the oil level adjustment step S2 are alternately performed.

[0044] Specifically, according to the control method of the compressor unit of some embodiments of the application, at least one working mode of the compressor unit 100 is: the normal working step S1 in which the compressor unit 100 normally operates according to the working condition requirements (refrigeration / heat, output power size, etc.), after the normal working step S1 is operated for a specified time, the oil level adjustment step S2 is switched to, in which the compressor unit 100 relatively changes the speed of the first compressor 1 or the second compressor 2 according to the speed of the first compressor 1 or the second compressor 2 in the normal working step S1 and continuously operates for a specified time to adjust the oil level balance inside the first compressor 1 and the second compressor 2. After the oil level adjustment step S2 is operated for a specified time, the compressor unit 100 returns to the normal working step S1 in which it normally operates according to the working condition requirements (refrigeration / heat, output power size, etc.), and the above process is repeated.

[0045] Taking the compressor unit of an air conditioner as an example, in combination with Figure 1 and Figure 3 , optionally, the normal working step S1 of the compressor unit 100 can include four working modes of the compressor unit 100: high output power + heating mode, high output power + refrigeration mode, low output power + heating mode, and low output power + refrigeration mode.

[0046] It should be noted that the high output power and the low output power are a relative concept, and are not an absolute high and low concept. It can be understood that the first compressor 1 and the second compressor 2 are in a high output power state when both of them are in a running state, and the first compressor 1 is in a low output power state when only the first compressor 1 is running and the second compressor 2 is stopped.

[0047] In the conventional working step S1, according to some embodiments of the present application, when the compressor set 100 works in the high output power + heating mode, the second compressor 2 runs at a constant speed, and the first compressor 1 runs at a variable speed according to the actual working condition and the load demand. At this time, the adjustable variable speed interval of the first compressor 1 is relatively large. When the compressor set 100 works in the high output power + cooling mode, the second compressor 2 runs at a constant speed, and the first compressor 1 runs at a variable speed according to the actual working condition and the load demand. At this time, the adjustable variable speed interval of the first compressor 1 is relatively small (within the adjustable variable speed interval of the first compressor 1 in the high output power + heating mode).

[0048] Since the first compressor 1 and the second compressor 2 in the compressor set 100 working in the two high output power modes are both kept running, and the internal pressures of the cavities of the first compressor 1 and the second compressor 2 are different, the oil levels in the first compressor 1 and the second compressor 2 are likely to be unbalanced after the compressor set 100 runs for a period of time.

[0049] In the conventional working step S1, according to some embodiments of the present application, when the compressor set 100 works in the low output power + heating mode, the second compressor 2 stops working, and the first compressor 1 runs at a variable speed according to the actual working condition and the load demand. At this time, the variable speed interval of the first compressor 1 can be large. When the compressor set 100 works in the low output power + cooling mode, the second compressor 2 stops working, and the first compressor 1 keeps running at a constant speed. Since the second compressor 2 in the compressor set 100 working in the two low output power modes is stopped, only the first compressor 1 runs alone, and thus the oil level of the first compressor 1 is likely to decrease due to the retention of the lubricating oil in the pipeline in the system.

[0050] In the oil level adjustment step S2, the rotation speed of the first compressor 1 and / or the second compressor 2 is changed and maintained for a specified time, which can make the pressure in the first compressor 1 and the second compressor 2 tend to balance, and is conducive to oil return and promoting the oil level balance in the first compressor 1 and the second compressor 2. Specifically, through the oil level adjustment step S2, the balance of the pressure in the compressor can be promoted while the return of the lubricating oil retained in the system is promoted, and the lubricating oil can flow from the compressor with a higher oil level to the compressor with less lubricating oil through the oil balance pipe 4, so as to realize the oil balance of the first compressor 1 and the second compressor 2. Therefore, without setting an oil separator or other oil return equipment, only by inserting the oil level adjustment step S2 in the conventional working step S1 of the compressor set 100, the oil balance / oil return operation of the compressor set 100 can be realized, and the stable operation of the compressor set 100 can be maintained for a long time.

[0051] According to the control method of the compressor set 100 in some embodiments of the present application, the oil level adjustment step S2 and the conventional working step S1 are alternately performed, that is, the oil level adjustment step S2 is performed between the execution of the conventional working step S1 of the compressor set 100.

[0052] Figure 4 An optional control method of a compressor set provided by some embodiments of the present application is shown. Referring to Figure 4 , if in the conventional working step S1, the compressor set 100 works in the high output power + heating mode, that is, both the first compressor 1 and the second compressor 2 work and heat, at this time, the first compressor 1 is in variable speed operation, according to the different total load demand of the compressor set, the first compressor 1 is adjusted in speed between the lower limit speed and the upper limit speed, and the second compressor 2 is always operated at a constant speed, so the oil level in the second compressor 2 and the oil level in the first compressor 1 are prone to imbalance. In this case, after the conventional working step S1 is operated for a specified time, the oil level adjustment step S2 is switched to, in which the rotation speed of the first compressor 1 is adjusted to a specified speed between the upper limit speed and the lower limit speed of the first compressor 1 in the conventional working step S1 in the high output power + heating mode and is maintained at the speed for a specified time. At this time, because the first compressor 1 is operated at the specified speed, the pressures in the cavities of the first compressor 1 and the second compressor 2 are balanced and stable, and in combination with the effects of the gas balance pipe 3 and the oil balance pipe 4, the gas pressures in the lubricating oil chambers of the second compressor 2 and the first compressor 1 can be balanced, and the lubricating oil can flow from the compressor with a higher oil level to the compressor with a lower oil level. After the oil balance step S2 is continuously operated for a specified time, it is switched back to the conventional working step S1, and the two steps are alternately and circularly switched, so as to maintain the oil balance of the first compressor 1 and the second compressor 2 during the operation of the compressor set 100.

[0053] If the compressor set 100 is operating in the high output power + refrigeration mode in the normal operation step S1, i.e. both the first compressor 1 and the second compressor 2 are running and refrigerating, the oil level of the first compressor 1 is higher than the normal oil level, while the oil level of the second compressor 2 is lower. In this case, the oil level adjustment step S2 can be switched to after the normal operation step S1 runs for a specified time. In the oil level adjustment step S2, the rotation speed of the first compressor 1 is adjusted to be equal to the upper limit rotation speed of the first compressor 1 in the normal operation step S1 in the high output power + refrigeration mode, and is kept stable for a specified time. By increasing the rotation speed of the first compressor 1 to the upper limit rotation speed, the outlet pressure of the first compressor 1 can be maximized to increase the system pressure, promote the return of the lubricating oil remaining in the system pipeline, and the first compressor 1 and the second compressor 2 are both in the constant speed operation, so that the pressure in the first compressor 1 and the second compressor 2 is balanced and stable, and therefore, in combination with the gas balance pipe 3 and the oil balance pipe 4, the gas pressure in the respective lubricating oil chambers of the second compressor 2 and the first compressor 1 can be balanced, and the lubricating oil can flow from the compressor with a higher oil level to the compressor with a lower oil level, so as to promote the oil level balance of the compressors. After the oil balance step S2 runs for a specified time, it is switched back to the normal operation step S1, and the two steps are alternately cycled, so as to maintain the oil balance of the first compressor 1 and the second compressor 2 during the operation of the compressor set 100.

[0054] If the compressor set 100 is operating in the low output power + heating mode in the normal operation step S1, i.e. the second compressor 2 is stopped, the first compressor 1 is running and heating, at this time, the rotation speed of the first compressor 1 is adjusted between the lower limit rotation speed and the upper limit rotation speed according to the actual working condition and load demand, the lubricating oil in the first compressor 1 is discharged together with the high-temperature and high-pressure refrigerant, and part of the lubricating oil remains in the system pipeline, and the lubricating oil in the second compressor 2 flows to the first compressor 1, but eventually leads to the decrease of the oil level of the first compressor 1 and the second compressor 2, and because there is an imbalance in the cavity pressure during the operation of the first compressor 1 and the second compressor 2, the oil level of the first compressor 1 and the second compressor 2 is imbalanced. In the case of low oil level of the second compressor 2, if the load of the compressor set 100 is suddenly adjusted and the second compressor 2 needs to be started urgently, the low oil level will have adverse effects.

[0055] To this end, after the regular working step S1 is run for a specified time, the oil level adjustment step S2 is switched to, in which the rotation speed of the first compressor 1 is adjusted to a specified rotation speed between the upper and lower limit rotation speeds of the first compressor 1 in the regular working step S1 in the low output power + heating mode, and is continuously run for a specified time. In the oil level adjustment step S2, because the first compressor 1 is always kept at a stable rotation speed, the system pressure of the entire compressor set 100 is stable, which is conducive to the return of the lubricating oil in the system, promotes the return of the lubricating oil remaining in the system pipeline to the first compressor 1 and the second compressor 2, and at the same time, the oil level in the first compressor 1 and the second compressor 2 is raised. After the oil level adjustment step S2 is continuously run for a specified time, it is switched back to the regular working step S1, and the two steps are alternately cycled, so that the return and normal oil level of the first compressor 1 and the second compressor 2 are balanced during the operation of the compressor set 100.

[0056] If the compressor set 100 works in the low output power + cooling mode in the regular working step S1, that is, the second compressor 2 is stopped, the first compressor 1 is running, and the cooling is in the case, at this time, the lubricating oil in the first compressor 1 is reduced due to the remaining in the system pipeline, and the lubricating oil in the second compressor 2 will continue to flow to the first compressor 1, but eventually leads to the oil level of the first compressor 1 and the second compressor 2 being reduced and unbalanced. To this end, after the regular working step S1 is run for a specified time, the rotation speed of the first compressor 1 is lowered to prepare for entering the oil level adjustment step S2, and then the oil level adjustment step S2 is switched to, in which the second compressor 2 is started, and at the same time, the rotation speed of the first compressor 1 is raised to a specified rotation speed and is always kept stable during the oil level adjustment step S2.

[0057] By appropriately adjusting the rotation speed of the first compressor 1 and starting the second compressor 2, and at the same time, keeping the rotation speed of the first compressor 1 stable during the oil level adjustment step S2, the lubricating oil remaining in the system pipeline can be promoted to return, and at the same time, the oil level in the first compressor 1 and the second compressor 2 is raised. After the oil level adjustment step S2 is continuously run for a specified time, it is switched back to the regular working step S1, and the two steps are alternately cycled, so that the return and oil level balance of the first compressor 1 and the second compressor 2 are maintained during the operation of the compressor set 100.

[0058] It is worth mentioning that when the compressor set 100 works in the low output power + cooling mode, if the rotation speed of the first compressor 1 is high in the regular working step S1, therefore, the rotation speed of the first compressor 1 is optionally lowered before the second compressor 2 is started, so that the pressure difference between the first compressor 1 and the second compressor 2 can be reduced, and the excessive pressure difference between the first compressor 1 and the second compressor 2 is avoided to affect the start of the second compressor 2.

[0059] In addition, the pre-reduced rotation speed of the first compressor 1 before starting the second compressor 2 is lower than the rotation speed of the first compressor 1 in the oil level adjustment step S2, which can be more conducive to the start of the second compressor 2. After entering the oil level adjustment step S2, the rotation speed of the first compressor 1 can be increased to the specified rotation speed.

[0060] In order to ensure that the output power of the compressor unit 100 does not fluctuate too much, in some optional embodiments, the continuous operation specified time of the oil level adjustment step S2 can be preferably 0-10 min, and the continuous operation specified time of the normal working step S1 can be preferably 0.5-2 h, and it is better that the continuous operation specified time of the oil level adjustment step S2 is shorter than the continuous operation specified time of the normal working step S1.

[0061] The following Figure 5 The control method of some embodiments of the application is illustrated by taking the cycle alternating mode that the normal working step S1 is switched to the oil level adjustment step S2 after 1 h of continuous operation, and the oil level adjustment step S2 is switched to the normal working step S1 after 5 min of continuous operation. By inserting the oil level adjustment step S2 with a shorter operation time into the normal working step S1 with a long operation time, the oil balance / oil return effect of the oil level adjustment step S2 can be ensured, and the output power stability of the compressor unit 100 can be maintained.

[0062] Figure 5 The first compressor and the second compressor in the control method of the compressor unit in the high-power output mode of some embodiments of the application are shown in the rotation speed switching schematic diagram. Figure 6 The first compressor and the second compressor in the control method of the compressor unit in the low-power output mode of some embodiments of the application are shown in the rotation speed switching schematic diagram.

[0063] Among them, the upper limit rotation speed and the lower limit rotation speed of the first compressor of the compressor unit in the normal working step S1 in different working modes can be determined by factors such as working condition requirements and compressor volume, which is not limited here. In order to facilitate the description, the first, second, third, and fourth naming methods are used for differentiation, which does not specifically refer to the high and low rotation speeds in different working modes.

[0064] The following Figure 5In the normal operation step S1, when the compressor set 100 is in the high power output + heating mode, the upper limit speed of the first compressor 1 is the first upper limit speed, the lower limit speed of the first compressor 1 is the first lower limit speed, and the first compressor 1 can be adjusted to operate between the first upper limit speed and the first lower limit speed. After the normal operation step S1 is operated for 1 h, the normal operation step S1 is switched to the oil level adjustment step S2. In the oil level adjustment step S2, the speed of the first compressor 1 is adjusted to the first specified speed (the first specified speed is between the first upper limit speed and the first lower limit speed of the first compressor in the normal operation step S1), and after the first compressor 1 is kept at the first specified speed for 5 min, the oil level adjustment step S2 is switched back to the normal operation step S1.

[0065] According to the test results of the applicant, when the first compressor 1 is continuously operated at the first upper limit speed for 1 h in the normal operation step S1, the oil level line of the first compressor 1 is obviously lower than the oil level line in the second compressor 2, and in particular, the oil level of the first compressor 1 is lower than the normal oil level line of the first compressor 1. After the oil level adjustment step S2 is adjusted for 5 min, the oil level line in the first compressor 1 is restored to be higher than the normal oil level line of the first compressor 1, and the oil level line in the second compressor 2 is lowered.

[0066] When the first compressor 1 is continuously operated at the first lower limit speed for 1 h, the oil level line in the second compressor 2 is lower than the oil level line in the first compressor 1, and in particular, the oil level in the second compressor 2 is lower than the normal oil level line of the second compressor 2. After the oil level adjustment step S2 is adjusted, the oil level line in the second compressor 2 is restored to be not lower than the normal oil level line of the second compressor 2, and the oil level line in the first compressor 1 is lowered.

[0067] In the normal operation step S1, when the compressor set 100 is in the high power output + heating mode, the upper limit speed of the first compressor 1 is the second upper limit speed, the lower limit speed of the first compressor 1 is the second lower limit speed, and the first compressor 1 can be adjusted to operate between the second upper limit speed and the second lower limit speed. After the normal operation step S1 is operated for 1 h, the normal operation step S1 is switched to the oil level adjustment step S2. In the oil level adjustment step S2, the speed of the first compressor 1 is adjusted and kept at the second specified speed (the second specified speed is equal to the second upper limit speed of the first compressor 1 in the normal operation step S1), and after the oil level adjustment step S2 is operated for 5 min, the oil level adjustment step S2 is switched back to the normal operation step S1.

[0068] According to the test results of the applicant, when the first compressor 1 continuously runs at the second upper limit speed in the normal working step S1 for 1 h, the oil level line in the second compressor 2 is lower than the oil level line in the first compressor 1, and after the oil level is adjusted for 5 min in the oil level adjustment step S2, the oil level line in the first compressor 1 is lowered. When the first compressor 1 continuously runs at the second lower limit speed in the normal working step S1 for 1 h, the oil level line in the second compressor 2 is lower than the oil level line in the first compressor 1, in particular, the oil level in the second compressor 2 has been lower than the normal oil level line of the second compressor 2, and after the oil level is adjusted for 5 min in the oil level adjustment step S2, the oil level line in the second compressor 2 is restored to not lower than the normal oil level line of the second compressor 2, and the oil level line in the first compressor 1 is lowered.

[0069] In combination Figure 6 When the compressor unit 100 is in the low power output + heating mode in the normal working step S1, the upper limit speed of the first compressor 1 is the third upper limit speed, the lower limit speed of the first compressor 1 is the third lower limit speed, the first compressor 1 can be adjusted and run between the third upper limit speed and the third lower limit speed, and the second compressor 2 is stopped. After the normal working step S1 runs for 1 h, the normal working step S1 is switched to the oil level adjustment step S2, in which the speed of the first compressor 1 is adjusted and maintained at the third specified speed (the third specified speed is between the third upper limit speed and the third lower limit speed of the first compressor 1 in the normal working step S1), and after the oil level adjustment step S2 runs for 5 min, the normal working step S1 is switched back.

[0070] According to the test results of the applicant, when the first compressor 1 continuously runs at the third upper limit speed in the normal working step S1 for 1 h, the oil level line in the first compressor 1 is slightly lower than the oil level line in the second compressor 2, and after the oil level adjustment step S2 is adjusted for 5 min, the oil level line in the first compressor 1 is raised, and the oil level line in the second compressor 2 is raised. When the first compressor 1 continuously runs at the third lower limit speed in the normal working step S1 for 1 h, the oil level line in the first compressor 1 is slightly higher than the oil level line in the second compressor 2, and after the oil level adjustment step S2 is adjusted for 5 min, the oil level line in the first compressor 1 is raised, and the oil level line in the second compressor 2 is raised.

[0071] In the normal working step S1, when the compressor set 100 is in the low power output + refrigeration mode, the first compressor 1 keeps running at the fourth speed for 1 hour in the normal working step S1, and then switches to the oil level adjustment step S2. Before entering the oil level adjustment step S2, the speed of the first compressor 1 can be reduced, and then the oil level adjustment step S2 is switched to. In the oil level adjustment step S2, the second compressor 2 runs, and the speed of the first compressor 1 is increased and kept at the fourth specified speed (the fourth specified speed is lower than the fourth speed of the first compressor 1 in the normal working step S1). After the first compressor 1 and the second compressor 2 keep running at the constant speed for 5 minutes in the oil level adjustment step S2, the normal working step S1 is jumped to.

[0072] According to the test results of the applicant, when the first compressor 1 runs continuously at the fourth speed for 1 hour in the normal working step S1, the oil level line of the first compressor 1 and the oil level line of the second compressor 2 are both low. After 5 minutes of adjustment in the oil level adjustment step S2, the oil level line of the first compressor 1 is increased, and the oil level line of the second compressor 2 is increased.

[0073] According to the control method of the compressor set 100 of the embodiment of the application, only the oil level adjustment step S2 needs to be alternately run in the normal working step S1 of the compressor set 100. For the compressor set 100 in the high power output mode, the oil level balance in the first compressor 1 and the second compressor 2 can be realized. For the compressor set 100 in the low power output mode, the oil return of the first compressor 1 and the second compressor 2 can be realized, the oil loss running of the first compressor 1 and / or the second compressor 2 is avoided, and the influence on the normal running of the compressor set 100 is very low, and the long-term stable running of the compressor set 100 can be maintained.

[0074] Second embodiment

[0075] In the optional embodiment of the application, a control device 200 capable of running the above control method is further provided. The control device 200 is in communication connection with the compressor set 100, and is used to produce instructions to control the running of the compressor set 100. The compressor set 100 has at least the first compressor 1 and the second compressor 2, and the first compressor 1 and the second compressor 2 are communicated through the gas balance pipe 3 and the oil balance pipe 4. In the optional embodiment, the first compressor 1 of the compressor set 100 is a variable speed compressor, and the second compressor 2 of the compressor set 100 is a constant speed compressor.

[0076] Figure 7 The control device structure schematic diagram of the compressor set provided by some embodiments of the application is shown. As shown in FIG. 2, the control device 200 is in communication connection with the compressor set 100, and is used to produce instructions to control the running of the compressor set 100. Figure 7As shown, the control device 200 comprises a regular working unit 5 and an oil level adjustment unit 6 which are alternately operated, the oil level adjustment unit 6 generates an instruction to change the rotating speed of the first compressor 1 and / or the second compressor 2 and continuously operates for a specified time to adjust the oil level inside the first compressor 1 and the second compressor 2. The control logic of the control device 200 is the same as the actions performed in the regular working step S1 and the oil level adjustment step S2, which will not be described herein.

[0077] In some optional embodiments, the continuous operation time of the compressor set 100 controlled by the oil level adjustment unit 6 is 0-10 minutes, and the continuous operation time of the compressor set 100 controlled by the regular working unit 5 is 0.5-2 hours. Hereinafter, the control process of the control device 200 will be described by way of example, in which the regular working unit 5 controls the compressor set 100 for 1 hour, then the oil level adjustment unit 6 controls the compressor set 100, and after 5 minutes, the regular working unit 5 controls the compressor set 100 again.

[0078] Optionally, the regular working unit 5 of the control device 200 can optionally comprise four working mode instructions: high power output + heating mode, high power output + cooling mode, low power output + heating mode, and low power output + cooling mode.

[0079] When the regular working unit 5 is working, the regular working unit 5 can generate a working mode instruction according to the working condition requirement, for example, the regular working unit 5 can generate a high power output + heating mode instruction, a high power output + cooling mode instruction, a low power output + heating mode instruction, or a low power output + cooling mode instruction, and the compressor set 100 operates in the corresponding working mode according to the received working mode instruction. After the regular working unit 5 controls the compressor set 100 to operate regularly for a specified time, the regular working unit 5 stops operating, and the oil level adjustment unit 6 operates. According to the type of the working mode instruction generated by the regular working unit 5 before, the oil level adjustment unit 6 generates a corresponding oil level adjustment instruction. The compressor set 100 changes the rotating speed of the first compressor 1 and the second compressor 2 according to the received oil level adjustment instruction, and maintains for a specified time. After that, the oil level adjustment unit 6 stops operating, and the regular working unit 5 operates. The above process is repeated alternately. Without the need to additionally set an oil separator, the oil balance / return of the compressor can be realized by adjusting the rotating speed of the first compressor 1 and / or the second compressor 2 through the oil level adjustment unit.

[0080] In addition, in each of the above embodiments of the control method, each step in the control method can be performed by a corresponding unit in the control device 100, or a plurality of steps can be performed by one unit, which will not be described herein.

[0081] It should be noted that the above merely represents several embodiments of the present application, and should not be construed as limiting the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control method of a compressor unit having a first compressor and a second compressor, the first compressor and the second compressor being communicated by a gas equalizing pipe and an oil equalizing pipe, characterized in that, the compressor unit has a normal operation step and an oil level adjustment step which are alternately operated, in the oil level adjustment step, the compressor unit is operated continuously for a prescribed time by changing the rotation speed of the first compressor or the second compressor to adjust the oil level of the first compressor and the second compressor.

2. The control method of the compressor unit according to claim 1, characterized by, the prescribed time of the continuous operation of the oil level adjustment step is 0-10 minutes.

3. The control method of the compressor unit according to claim 1, characterized by, the prescribed time of the continuous operation of the normal operation step is 0.5-2 hours.

4. The control method of the compressor unit according to claim 1, characterized by, the first compressor of the compressor unit is a variable speed compressor, and the second compressor of the compressor unit is a fixed speed compressor.

5. The control method of the compressor unit according to claim 4, characterized in that, a one-way valve is further provided at the outlet of the second compressor.

6. The control method of a compressor unit according to claim 5, characterized in that, if the compressor unit is operated in a heating condition and both the first compressor and the second compressor are operated, in the oil level adjustment step, the rotation speed of the first compressor is controlled to be set between the upper limit rotation speed and the lower limit rotation speed of the first compressor. if the compressor unit is operated in a cooling condition and both the first compressor and the second compressor are operated, in the oil level adjustment step, the rotation speed of the first compressor is controlled to be set equal to the upper limit rotation speed of the first compressor.

7. The control method of the compressor unit according to claim 5, characterized by, if the compressor unit is operated in a heating condition and the first compressor is operated and the second compressor is stopped, in the oil level adjustment step, the rotation speed of the first compressor is controlled to be set between the upper limit rotation speed and the lower limit rotation speed of the first compressor.

8. The control method of the compressor unit according to claim 5, characterized by, if the compressor unit is operated in a cooling condition and the first compressor is operated and the second compressor is stopped, in the oil level adjustment step, the second compressor is started and the first compressor is adjusted to be lower than the upper limit rotation speed of the first compressor.

9. The control method of the compressor unit according to claim 8, characterized by, if the compressor unit is operated in a cooling condition and the first compressor is operated and the second compressor is stopped, the rotation speed of the first compressor is decreased before the second compressor is started.

10. A control device of a compressor unit having a first compressor and a second compressor which are communicated through a gas balance pipe and an oil balance pipe, characterized by, the control device includes a normal operation unit and an oil level adjustment unit which are alternately operated, the oil level adjustment unit generates an instruction to change the rotation speed of the first compressor and / or the second compressor and to be operated continuously for a prescribed time to adjust the oil level of the first compressor and the second compressor.

11. The control device for a compressor unit according to claim 10, wherein the first compressor of the compressor unit is a variable speed compressor, and the second compressor of the compressor unit is a fixed speed compressor.

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