Air conditioning system and control method thereof

Abstract

The invention relates to the technical field of air conditioning systems, the air conditioning system further comprises a refrigerant circulation pipeline, and a compressor, a condenser and an evaporator are arranged on the refrigerant circulation pipeline; the bearing and the liquid separation ring are sleeved on the compressor rotating shaft; the air conditioning system further comprises a subcooler, the subcooler is connected with the evaporator through a subcooling liquid supply pipe, the subcooler is connected with the compressor through a bearing liquid supply pipe, a heat exchange pipe is arranged in the subcooler, and the heat exchange pipe is connected with the subcooling liquid supply pipe through a liquid supply pipe branch. A fluorine pump is arranged on the supercooling liquid supply pipe, a first valve body is arranged on a branch of the liquid supply pipe, and the compressor is connected with the evaporator through a bearing liquid return pipe. When the air conditioner runs, pressure liquid passing through a fluorine pump is arranged in front of the first valve body, an evaporator low-pressure area is arranged behind the first valve body, and under the action of pressure difference, a refrigerant absorbs heat in a flash evaporation mode after being throttled at the first valve body and absorbs heat of the refrigerant in a subcooler after entering a heat exchange pipe, so that the refrigerant before entering a bearing reaches a certain supercooling degree, and flash evaporation gasification is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning systems, and specifically provides an air conditioning system and a control method thereof. Background Art

[0002] Traditional air-conditioning centrifugal units lubricate the bearings of centrifugal compressors through lubricating oil. Therefore, a separate oil lubrication and oil separation system is required to lubricate the bearings. However, due to its complex maintenance and high cost, an oil-free centrifugal compressor with a refrigerant lubricating bearing system has emerged in the air-conditioning centrifugal water-cooled unit market. This kind of bearing does not require lubricating oil and can use the refrigerant liquid of the unit itself as a lubricant. Therefore, the proportion of oil-free centrifugal units that are maintenance-free and have a simpler structure is increasing. However, due to the characteristic that the liquid refrigerant is prone to flash evaporation with the change of temperature or pressure, it is determined that if the refrigerant liquid supplied to the bearing for lubrication has completely or partially flashed before entering the bearing to form a lubricating film, the bearing cannot achieve the lubrication effect, which will affect the bearing life and even cause damage, and also bring risks to the normal operation of the compressor.

[0003] Correspondingly, there is a need in the art for a new air conditioning system to solve the problem that the existing compressor bearings cannot achieve the lubrication effect due to refrigerant flash evaporation and vaporization. Summary of the Invention

[0004] The present invention aims to solve the above technical problems, that is, to solve the problem that the existing compressor bearings cannot achieve the lubrication effect due to refrigerant flash evaporation and vaporization.

[0005] The present invention provides a bearing lubrication structure, which includes a bearing, a bearing mounting seat, and a liquid distribution ring. The liquid distribution ring is arranged in parallel with the bearing in the bearing mounting seat. A liquid storage groove is provided on the liquid distribution ring. The end face of the liquid storage groove abuts against the inner wall of the bearing mounting seat to form a cavity for accommodating the refrigerant. Liquid spraying holes are provided on the wall of the liquid storage groove and face the bearing.

[0006] In the case of adopting the above technical solution, when the air-conditioning centrifugal unit is running, liquid refrigerant is continuously injected into the liquid storage groove through the refrigerant pipe of the air conditioning system. The refrigerant sprays the refrigerant towards the bearing through the liquid spraying holes for lubrication. After the air-conditioning centrifugal unit is powered off and the refrigerant cannot be provided continuously, the bearing will still continue to rotate under the action of inertia. At this time, the refrigerant stored in the liquid storage groove can continue to provide lubrication for the bearing. Therefore, after the power-off emergency shutdown, the bearing can still be lubricated and protected, realizing the safe shutdown of the unit, preventing the reduction of the bearing life and the damage of the bearing, and because the liquid distribution ring can spray and lubricate the adjacent bearing in a targeted manner, the required spraying pressure is smaller and the lubrication effect is better.

[0007] In an alternative technical solution of the above bearing lubrication structure, an auxiliary liquid storage groove is provided on the bearing mounting seat. After the end face of the liquid storage groove abuts against the inner wall of the bearing mounting seat, the auxiliary liquid storage groove and the liquid storage groove together form a cavity for accommodating a refrigerant.

[0008] In the case of adopting the above technical solution, the auxiliary liquid storage groove and the liquid storage groove together form a cavity for accommodating a refrigerant, which increases the volume of the cavity to accommodate more refrigerant while not increasing the space occupied by the liquid storage groove.

[0009] In an alternative technical solution of the above bearing lubrication structure, the number of bearings is two, the liquid distribution ring is arranged between the two bearings, and liquid spraying holes facing the two bearings are respectively arranged on two side walls of the liquid storage groove.

[0010] In the case of adopting the above technical solution, the liquid distribution ring can spray both side bearings simultaneously, thereby improving the spraying efficiency.

[0011] In an alternative technical solution of the above bearing lubrication structure, a liquid inlet communicating with the liquid storage groove is provided on the bearing mounting seat and / or the liquid distribution ring.

[0012] In the case of adopting the above technical solution, the refrigerant is injected into the liquid storage groove through the liquid inlet.

[0013] In an alternative technical solution of the above bearing lubrication structure, a convex platform is provided on the liquid distribution ring, and the convex platform abuts against the side part of the outer ring of the bearing.

[0014] In the case of adopting the above technical solution, the liquid distribution ring and the bearing abut and support each other to improve stability.

[0015] In an alternative technical solution of the above bearing lubrication structure, a sealing structure is provided between the liquid distribution ring and the bearing mounting seat.

[0016] In the case of adopting the above technical solution, the liquid distribution ring and the bearing mounting seat are sealed to prevent liquid leakage from non-liquid spraying holes.

[0017] The present invention also provides an air-conditioning system, which includes the bearing lubrication structure according to any one of the above technical solutions; the air-conditioning system further includes a refrigerant circulation pipeline, on which a compressor, a condenser, and an evaporator are arranged; the air-conditioning system further includes a subcooler, the subcooler and the evaporator are connected by a subcooling liquid supply pipe, the subcooler and the compressor are connected by a bearing liquid supply pipe, a heat exchange pipe is arranged in the subcooler, and the heat exchange pipe is connected to the subcooling liquid supply pipe through a liquid supply pipe branch; a fluorine pump is arranged on the subcooling liquid supply pipe, a first valve body is arranged on the liquid supply pipe branch, and the compressor and the evaporator are connected by a bearing liquid return pipe;

[0018] So that the refrigerant in the evaporator enters the subcooler and the heat exchange tube respectively. Among them, the refrigerant that enters the heat exchange tube after throttling by the first valve body absorbs the heat of the refrigerant in the subcooler. The subcooled refrigerant in the subcooler lubricates the bearing through the bearing liquid supply pipe, and the lubricated refrigerant returns to the evaporator through the bearing liquid return pipe.

[0019] In the case of adopting the above technical solution, in front of the first valve body is the pressure liquid passing through the fluorine pump, and behind is the low-pressure area of the evaporator. Thus, under the action of the pressure difference, the refrigerant throttles at the first valve body, and the liquid will flash and absorb heat. By absorbing the heat of the liquid refrigerant in the subcooler, the liquid reaches a certain degree of subcooling, avoiding the flashing and gasification of the refrigerant liquid before entering the bearing to achieve the lubrication effect. The liquid forms a lubricating film in the bearing, achieving the purpose of fully lubricating the bearing.

[0020] In an alternative technical solution of the above air-conditioning system, the condenser and the subcooler are connected by a balance pipe, and a normally open solenoid valve is arranged on the balance pipe.

[0021] In the case of adopting the above technical solution, the high-pressure balance pipeline from the condenser to the subcooler is used to automatically keep the subcooler at high pressure to continue supplying liquid for bearing lubrication during power-off emergency shutdown without any electrical control of the air-conditioning system. Specifically, after the unit is powered off, the normally open solenoid valve loses power and opens. In the initial stage of power-off, the pressure of the condenser is higher than that of the subcooler. The high-pressure refrigerant gas enters the subcooler from the condenser through the pipeline, forming a liquid supply pressure difference for the bearing and continuing to provide lubrication for the bearing until the pressure of the condenser drops to balance with the pressure of the subcooler, and the condenser no longer provides the liquid supply pressure, so as to provide lubrication for the bearing for a longer time.

[0022] In an alternative technical solution of the above air-conditioning system, a first one-way valve is arranged on the balance pipe; and / or, a second one-way valve is arranged on the subcooled liquid supply pipe.

[0023] In the case of adopting the above technical solution, when the pressure of the condenser drops to balance with the pressure of the subcooler after power-off, the condenser no longer provides pressure, and the normally open solenoid valve is in the open state. The first one-way valve is used to prevent the pressure in the subcooler from flowing back to the condenser after the pressures of the condenser and the subcooler are balanced after a period of time after power-off, maintaining the pressure in the subcooler and better continuing to supply liquid. The second one-way valve prevents the pressure refrigerant in the subcooler from flowing back to the evaporator after power-off.

[0024] In an alternative technical solution of the above air-conditioning system, the compressor and the condenser are connected by a motor cooling pipe, and the compressor is connected to the evaporator through a return air pipe, so that the refrigerant in the condenser cools the motor and then enters the evaporator through the return air pipe.

[0025] In the case of adopting the above technical solution, the high-temperature liquid refrigerant after releasing heat at the condenser cools the compressor motor by flashing and absorbing heat at the motor, and then enters the evaporator through the return air pipe.

[0026] In an alternative technical solution of the above air-conditioning system, a liquid supplement pipe is connected between the condenser and the evaporator, and a second valve body is arranged on the liquid supplement pipe.

[0027] In the case of adopting the above technical solution, when the refrigerant in the evaporator liquid bladder is insufficient, the refrigerant required for lubrication is supplemented from the condenser to the evaporator through the liquid supplement pipe.

[0028] In an alternative technical solution of the above air-conditioning system, the air-conditioning system includes an economizer, the economizer is arranged on the pipeline between the condenser and the evaporator, and the economizer is connected to the compressor through a gas supplement pipe to supplement gas to the compressor.

[0029] In the case of adopting the above technical solution, the gaseous refrigerant at the compressor outlet enters the condenser through the exhaust pipe to release heat, and the economizer flashes and separates the heat-released refrigerant into gas and liquid. Among them, the liquid sub-cooled refrigerant at the bottom of the economizer enters the evaporator through the liquid inlet pipe to absorb heat, and then returns to the compressor through the compressor suction pipe. The economizer is connected to the gas supplement port of the compressor through the gas supplement pipe, and the flashed gaseous refrigerant enters the compressor through the gas supplement pipe to supplement gas, and the unit achieves the effect of gas supplement and enthalpy increase to improve the unit efficiency.

[0030] The present invention also provides a control method for an air-conditioning system. The air-conditioning system includes the bearing lubrication structure described in any of the above technical solutions; the air-conditioning system further includes a refrigerant circulation pipeline, and a compressor, a condenser, and an evaporator are arranged on the refrigerant circulation pipeline; the air-conditioning system further includes a sub-cooler, the sub-cooler and the evaporator are connected through a sub-cooled liquid supply pipe, the sub-cooler and the compressor are connected through a bearing liquid supply pipe, a heat exchange pipe is arranged in the sub-cooler, and the heat exchange pipe is connected to the sub-cooled liquid supply pipe through a liquid supply pipe branch; a fluorine pump is arranged on the sub-cooled liquid supply pipe, a first valve body is arranged on the liquid supply pipe branch, and the compressor and the evaporator are connected through a bearing liquid return pipe;

[0031] So that the refrigerant in the evaporator enters the sub-cooler and the heat exchange pipe respectively, and the refrigerant entering the heat exchange pipe after throttling by the first valve body absorbs the heat of the refrigerant in the sub-cooler. The sub-cooled liquid refrigerant in the sub-cooler lubricates the bearing through the bearing liquid supply pipe, and the lubricated refrigerant returns to the evaporator through the bearing liquid return pipe;

[0032] The control method includes:

[0033] Obtain the bearing lubrication supply pressure P1, the bearing lubrication return pressure P2, and the bearing lubrication supply temperature T1;

[0034] Calculate the bearing supply pressure difference △P = P1 - P2;

[0035] Adjust the rotation speed of the fluorine pump according to the bearing supply pressure difference △P; alternatively, the control method includes:

[0036] Obtain the bearing lubrication supply flow value;

[0037] Compare the bearing lubrication supply flow value with the lubrication supply amount required by the bearing design to adjust the rotation speed of the fluorine pump.

[0038] In the case of adopting the above technical solution, the rotation speed of the fluorine pump is controlled by the bearing supply pressure difference to accurately control the heat absorption capacity of the heat exchange tube. Alternatively, the rotation speed of the fluorine pump can also be adjusted by the bearing lubrication supply flow, so as to maintain the supply flow, and further control the heat absorption capacity of the heat exchange tube.

[0039] In the optional technical solution of the control method of the above air conditioning system, the control method includes:

[0040] Calculate the saturation temperature T2 corresponding to the refrigerant according to P1;

[0041] Calculate the subcooling degree △T of the refrigerant = T2 - T1;

[0042] Adjust the opening degree of the first valve body according to the subcooling degree △T.

[0043] In the case of adopting the above technical solution, the opening degree of the first valve body is adjusted by the subcooling degree, so that the subcooling degree is always maintained within the optimal range, which can not only reduce energy consumption, but also sufficiently cool the refrigerant, and avoid flashing and gasification of the refrigerant before entering the bearing to achieve the lubrication and cooling effects, thereby affecting the lubrication effect.

[0044] In the optional technical solution of the control method of the above air conditioning system, a liquid supplement pipe is connected between the condenser and the evaporator, and a second valve body is arranged on the liquid supplement pipe;

[0045] The control method includes:

[0046] After receiving the signal to start the compressor, obtain the liquid level height in the evaporator liquid bladder;

[0047] When the liquid level height in the evaporator liquid bladder is less than the preset liquid level height, control the second valve body to open;

[0048] When the liquid level height in the evaporator liquid bladder is greater than or equal to the preset liquid level height, control the second valve body to close.

[0049] In the case of adopting the above technical solution, before the compressor is started, the second valve body is controlled to open to supplement the evaporator with refrigerant from the condenser when the refrigerant in the evaporator liquid pocket is insufficient, preventing insufficient lubricating liquid.

[0050] In an alternative technical solution of the control method of the above air-conditioning system, after the step of "when the liquid level height in the evaporator liquid pocket is greater than or equal to the preset liquid level height, control the second valve body to close", the control method includes:

[0051] Control the compressor to start and control the fluorine pump to open;

[0052] When it is detected that the liquid level height in the evaporator liquid pocket is less than the preset liquid level height, and after the second valve body is opened for a first preset time period and the liquid level height in the evaporator liquid pocket is still less than the preset liquid level height, control the fluorine pump and the compressor to close.

[0053] In the case of adopting the above technical solution, after the liquid level in the evaporator is sufficient, control the unit to start, start the fluorine pump to lubricate the bearing, and at the same time, when it is detected that the liquid level height in the evaporator liquid pocket is less than the preset liquid level height, and after the normally closed solenoid valve is opened for a first preset time period and the liquid level height in the evaporator liquid pocket is still less than the preset liquid level height, control the fluorine pump and the compressor to close, thereby preventing damage to the bearing.

[0054] Those skilled in the art can understand that the air-conditioning system of the present invention further includes a refrigerant circulation pipeline, on which a compressor, a condenser, and an evaporator are provided; the air-conditioning system further includes a subcooler, the subcooler and the evaporator are connected by a subcooling liquid supply pipe, the subcooler and the compressor are connected by a bearing liquid supply pipe, a heat exchange pipe is provided in the subcooler, and the heat exchange pipe is connected to the subcooling liquid supply pipe through a liquid supply pipe branch; a fluorine pump is provided on the subcooling liquid supply pipe, a first valve body is provided on the liquid supply pipe branch, and the compressor and the evaporator are connected by a bearing liquid return pipe;

[0055] So that the refrigerant in the evaporator enters the subcooler and the heat exchange pipe respectively. Among them, the refrigerant that enters the heat exchange pipe after throttling by the first valve body absorbs the heat of the refrigerant in the subcooler, and the subcooled refrigerant in the subcooler lubricates the bearing through the bearing liquid supply pipe, and the lubricated refrigerant returns to the evaporator through the bearing liquid return pipe.

[0056] In the case of adopting the above technical solution, when the air-conditioning unit is operating, the pressure liquid passing through the fluorine pump is in front of the first valve body, and the low-pressure area of the evaporator is behind. Thus, under the action of the pressure difference, the refrigerant throttles at the first valve body, and the refrigerant liquid flashes and absorbs heat. Furthermore, the refrigerant in the heat exchange tube absorbs the heat of the liquid refrigerant in the subcooler, causing the liquid in the subcooler to reach a certain degree of subcooling, preventing the refrigerant liquid from flashing and vaporizing before entering the bearing to achieve the lubrication effect. The liquid forms a lubricating film in the bearing, achieving the purpose of fully lubricating the bearing. Description of the Drawings

[0057] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

[0058] Figure 1 is a schematic diagram of the air-conditioning system of the present invention;

[0059] Figure 2 A longitudinal sectional view of an embodiment of the bearing lubrication structure of the present invention;

[0060] Figure 3 is a longitudinal sectional view of another embodiment of the bearing lubrication structure of the present invention;

[0061] Figure 4 is a side view of the liquid distribution ring of the present invention;

[0062] Figure 5 is Figure 4 a cross-sectional view taken along line A-A in [], which is one embodiment;

[0063] Figure 6 is Figure 4 a cross-sectional view taken along line A-A in [], which is another embodiment;

[0064] Figure 7 is a step flowchart of one embodiment of the control method of the air-conditioning system of the present invention;

[0065] Figure 8 is a step flowchart of another embodiment of the control method of the air-conditioning system of the present invention.

[0066] List of Reference Numerals:

[0067] 1, centrifugal compressor; 11', rotating shaft; 2, ceramic rolling bearing; 21, liquid distribution ring; 211, liquid storage tank; 212, liquid spraying hole; 213, convex platform; 22, bearing mounting seat; 221, auxiliary liquid storage tank; 25, sealing ring; 3, condenser; 4, economizer; 5, evaporator; 6, fluorine pump; 7, second check valve; 8, electronic expansion valve; 9, subcooler; 10, heat exchange tube; 11, flowmeter; 13, electric valve; 14, third check valve; 15, normally closed solenoid valve; 16, normally open solenoid valve; 17, first check valve;

[0068] 101, exhaust pipe; 102, liquid line pipe; 103, liquid inlet pipe; 104, suction pipe; 105, make-up gas pipe; 106, subcooled liquid supply pipe; 1061, liquid supply pipe branch; 107, bearing liquid supply pipe; 108, bearing liquid return pipe; 109, liquid return pipe; 110, subcooled liquid return pipe; 111, motor cooling pipe; 112, return gas pipe; 113, liquid supplement pipe; 114, balance pipe;

[0069] 201, condenser pressure sensor; 202, evaporator pressure sensor; 203, refrigerant liquid level switch; 204, subcooler pressure sensor; 205, subcooler temperature sensor; 206, bearing liquid return pressure sensor. Specific embodiments

[0070] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention. Those skilled in the art can adjust them as needed to adapt to specific application scenarios. For example, although the bearing lubrication structure of the present application is described in conjunction with the centrifugal compressor of an air-conditioning centrifugal chiller, this is not restrictive. The bearing lubrication structure of the present invention can also be applied to other types of compressors and air-conditioning systems, such as piston compressors, rotary screw compressors, etc., and can also be applied to other devices that require a bearing lubrication structure other than air conditioners.

[0071] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "center", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0072] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] Refer to Figures 1 to 6, the present invention provides a bearing lubrication structure. The bearing lubrication structure includes a bearing 2, a liquid distribution ring 21, and a bearing mounting seat 22. The liquid distribution ring 21 and the bearing 2 are arranged side by side in the bearing mounting seat 22. A liquid storage groove 211 is provided on the liquid distribution ring 21. The end face of the liquid storage groove 211 abuts against the inner wall of the bearing mounting seat 22 to form a cavity. A liquid spraying hole 212 facing the bearing 2 is provided on the liquid storage groove 211. After the external refrigerant pipe injects refrigerant into the liquid storage groove 211, the liquid spraying hole 212 sprays the refrigerant towards the bearing 2 to lubricate the bearing 2. When the air-conditioning system is powered off, the refrigerant stored in the liquid storage groove 211 and the refrigerant in the subcooler 9 can jointly continue to provide lubrication and cooling for the bearing 2 under the pressure of the condenser 3.

[0074] The advantages of the above setting method are as follows: When the air-conditioning centrifugal unit is running, the refrigerant is continuously injected into the liquid storage groove 211 through the refrigerant pipe of the air-conditioning system. The refrigerant sprays the refrigerant towards the bearing 2 through the liquid spraying hole 212 for lubrication. After the air-conditioning centrifugal unit is powered off and the refrigerant cannot be continuously provided, the bearing 2 will continue to rotate under the action of inertia. At this time, the refrigerant stored in the liquid storage groove 211 and the refrigerant in the subcooler 9 can jointly continue to provide lubrication and cooling for the bearing 2 under the pressure of the condenser 3. Therefore, after an emergency shutdown due to power failure, the bearing 2 can still be lubricated and protected, realizing safe shutdown of the unit, preventing reduction of the bearing life and damage to the bearing. And because the liquid distribution ring 21 can spray lubricate the adjacent bearing in a targeted manner, its lubrication effect is better.

[0075] Referring to Figures 2 to 6 , in a possible implementation manner, the bearing lubrication structure includes a bearing 2, a liquid distribution ring 21, and a bearing mounting seat 22. The liquid distribution ring 21 and the bearing 2 are fixedly arranged side by side in the bearing mounting seat 22, and the centers of the liquid distribution ring 21 and the bearing 2 are sleeved on the centrifugal compressor rotating shaft 11'. There is a certain gap between the liquid distribution ring 21 and the rotating shaft 11'. When the rotating shaft 11' rotates, the inner ring of the bearing rotates with the rotating shaft 11', and the liquid distribution ring 21 and the outer ring of the bearing do not rotate with the rotating shaft 11'. Those skilled in the art can install and limit the bearing 2 on the bearing mounting seat 22 and the rotating shaft 11' in the form of a shaft shoulder, a spring, or a pressing plate as needed. The sealing groove of the liquid distribution ring 21 and the bearing mounting seat 22 is sealed in the form of an O-ring 25 to prevent liquid from leaking from non-liquid spraying holes 212. Optionally, the liquid distribution ring 21 can be connected to the bearing mounting seat 22 by screws, or a clamping groove can be provided on the bearing mounting seat 22 to clamp the liquid distribution ring 21 in the clamping groove for connection, etc. Those skilled in the art can set the connection method between the liquid distribution ring 21 and the bearing mounting seat 22 as needed, and all fall within the protection scope of the present invention.

[0076] Referring to Figure 2, when the number of bearings 2 is one and the liquid distribution ring 21 is arranged side by side with the bearing 2 on one side, a boss 213 is arranged on one side of the liquid distribution ring 21, and the boss 213 abuts against the side of the bearing outer ring to improve stability. A liquid spraying hole 212 for spraying the coolant towards the bearing 2 is arranged on the side wall of the liquid storage tank 211 close to the bearing 2. Refer to Figure 3 , when the number of bearings 2 is at least two and bearings 2 are respectively arranged on both the left and right sides of the liquid distribution ring 21, bosses 213 are respectively formed on both side walls of the liquid distribution ring 21, and the bosses 213 abut against the sides of the bearing outer rings to improve stability. Liquid spraying holes 212 towards the bearings 2 are arranged on both side walls of the liquid storage tank 211. Of course, those skilled in the art can set the position of the liquid spraying holes 212 as needed, as long as the liquid can be sprayed towards the bearings 2, and all fall within the protection scope of the present invention. Further, in order to increase the liquid storage capacity of the liquid storage tank 211, an auxiliary liquid storage tank 221 is arranged on the inner wall of the bearing mounting seat 22. The opening of the auxiliary liquid storage tank 221 faces the opening of the liquid storage tank 211. The auxiliary liquid storage tank 221 and the liquid storage tank 211 jointly form a cavity for accommodating the refrigerant, improving the volume of the cavity to accommodate more refrigerant while not increasing the occupied space of the liquid storage tank 211.

[0077] Optionally, a liquid inlet (not shown in the figure) communicating with the liquid storage tank 211 is arranged on the liquid distribution ring 21, or a liquid inlet (not shown in the figure) communicating with the liquid storage tank 211 can also be arranged on the bearing mounting seat 22. Those skilled in the art can set it as needed, and all fall within the protection scope of the present invention.

[0078] In addition, the cross-sectional shape of the liquid storage tank 211 can be square, circular, etc. It can be arranged in a ring around the liquid distribution ring 21 or be a part of the ring. Those skilled in the art can set the shape and structure of the liquid storage tank 211 as needed, and the present invention does not make any restrictions on this, and all fall within the protection scope of the present invention. Moreover, the number of the liquid spraying holes 212 can be one or more. Those skilled in the art can set the number of the liquid spraying holes 212 as needed, and it falls within the protection scope of the present invention. In addition, the present invention does not make any restrictions on the sealing form between the liquid distribution ring 21 and the bearing mounting seat 22. In addition to being sealed by the sealing ring 25, it can also be sealed by gaskets, threaded structures, labyrinth structures, etc. Those skilled in the art can set the sealing structure as needed, and all fall within the protection scope of the present invention.

[0079] Due to the easy flashing characteristic of the liquid refrigerant, it also determines that if not properly handled, the liquid refrigerant supplied to lubricate the bearing has completely or partially flashed before entering the bearing to form a lubricating film, failing to achieve the lubricating effect and affecting the bearing life or even causing damage. To solve the above technical problems, refer toFigure 1 In addition, the present invention also provides an air conditioning system. In a possible implementation manner, the air conditioning system includes a centrifugal compressor 1, a condenser 3, an economizer 4, an evaporator 5, a refrigerant pump 6, an electronic expansion valve 8, a subcooler 9, and a heat exchange tube 10. The centrifugal compressor 1 is provided with the bearing lubrication structure and the motor in the above implementation manner. The ceramic rolling bearing 2 and the liquid distribution ring 21 are sleeved on the compressor rotating shaft 11'. The inner ring of the bearing rotates with the rotating shaft 11', while the liquid distribution ring 21 and the outer ring of the bearing do not rotate with the rotating shaft 11'. The liquid injection holes 212 spray the coolant towards the bearing 2 for lubrication. Figure 1 The arrow in [description of Figure] indicates the schematic flow direction of the refrigerant when the air conditioning system is refrigerating.

[0080] It should be noted that although the present invention is described with a ceramic rolling bearing, it is not intended to impose any restrictions on the specific structure of the bearing 2. It can be any bearing that can be lubricated without oil. Those skilled in the art can set the type and structure of the bearing 2 according to needs, and all fall within the protection scope of the present invention.

[0081] Specifically, the air outlet of the centrifugal compressor 1 is connected to the condenser 3 through an exhaust pipe 101, the condenser 3 and the economizer 4 are connected through a liquid pipeline 102, the economizer 4 and the evaporator 5 are connected through a liquid inlet pipe 103, and the evaporator 5 and the suction port of the centrifugal compressor 1 are connected through a suction pipe 104 to form a refrigerant circulation loop. The gaseous refrigerant at the compressor outlet enters the condenser 3 through the exhaust pipe 101 to release heat. The economizer 4 performs flash separation on the refrigerant after heat release into gaseous and liquid states. Among them, the liquid subcooled refrigerant at the bottom of the economizer 4 enters the evaporator 5 through the liquid inlet pipe 103 to absorb heat, and then returns to the centrifugal compressor 1 through the suction pipe 104.

[0082] Furthermore, the economizer 4 is connected to the air supplement port of the centrifugal compressor 1 through a supplementary air pipe 105. The flashed gaseous refrigerant enters the compressor through the supplementary air pipe 105 for air supplement, enabling the unit to achieve the effect of air supplement and enthalpy increase and improving the unit efficiency. An electric valve 13 is provided on the supplementary air pipe 105 to control the connection between the economizer 4 and the air supplement port. A third one-way valve 14 is provided on the exhaust pipe 101. The third one-way valve 14 only allows the refrigerant of the compressor to flow towards the condenser 3 direction, preventing the high pressure on the exhaust side from flowing back and causing the compressor to reverse and be damaged.

[0083] Further, the evaporator 5 and the subcooler 9 are connected by a subcooling liquid supply pipe 106. A fluorine pump 6 is provided on the subcooling liquid supply pipe 106. A liquid supply pipe branch 1061 of the subcooling liquid supply pipe 106 is connected to a heat exchange pipe 10 inside the subcooler 9. The subcooler 9 and the centrifugal compressor 1 are connected by a bearing liquid supply pipe 107 to inject refrigerant into the liquid storage tank 211 through the bearing liquid supply pipe 107. An electronic expansion valve 8 is provided on the liquid supply pipe branch 1061. The heat exchange pipe 10 and the evaporator 5 are connected by a subcooling liquid return pipe 110 and a liquid return pipe 109. The centrifugal compressor 1 and the evaporator 5 are connected by a bearing liquid return pipe 108 and a liquid return pipe 109. The electronic expansion valve 8 throttles the refrigerant in the liquid supply pipe branch 1061 into a low-temperature gas-liquid two-phase refrigerant. Then, the heat exchange pipe 10 exchanges heat with the refrigerant in the subcooler 9, absorbing the heat of the refrigerant in the subcooler 9. The subcooled refrigerant in the subcooler 9 is injected into the liquid storage tank 211 through the bearing liquid supply pipe 107 to lubricate the bearing 2, and then enters the evaporator 5 through the bearing liquid return pipe 108 and the liquid return pipe 109.

[0084] It should be noted that for the electronic expansion valve 8 to function, there must be a pressure difference before and after. Therefore, in front of the electronic expansion valve 8 is the pressurized liquid passing through the fluorine pump 6, and behind is the low-pressure area of the evaporator 5. Under the action of the pressure difference, the refrigerant throttles at the electronic expansion valve 8, and the liquid in the heat exchange pipe 10 will flash and absorb heat, achieving a certain degree of subcooling of the liquid refrigerant by absorbing the heat of the liquid refrigerant in the subcooler 9, and preventing the refrigerant liquid from flashing and vaporizing before entering the bearing to achieve the lubrication effect and thus affecting the lubrication effect. In addition, when the fluorine pump 6 is operating, even if the liquid storage tank 211 was originally filled with refrigerant gas, due to the fact that the refrigerant injected into the liquid storage tank 211 is subcooled, it will absorb heat to condense this part of the gas to reach liquefaction and subcooling, and the liquid will gradually fill the liquid storage tank 211, serving as a reserve for liquid supply in case of power failure and emergency shutdown.

[0085] Further, a second one-way valve 7 is provided between the fluorine pump 6 and the subcooler 9. The second one-way valve 7 only allows the refrigerant to flow from the fluorine pump 6 towards the subcooler 9, and the second one-way valve 7 prevents the pressured refrigerant in the subcooler 9 from flowing back to the evaporator 5 after power failure.

[0086] It should be noted that the electronic expansion valve 8 can also be replaced with other types of valve bodies that can adjust the opening degree, such as a thermal expansion valve or a solenoid valve, etc. Those skilled in the art can set the type of the first valve body (electronic expansion valve 8) according to needs, and all fall within the protection scope of the present invention. In addition, the present invention does not impose any restrictions on the structure of the subcooler 9. For example, the subcooler 9 and the heat exchange pipe 10 can also be replaced with a sleeve structure, etc., as long as it can achieve the purpose of internal and external refrigerant heat exchange so that the internal liquid has a degree of subcooling. Those skilled in the art can set the structures of the subcooler 9 and the heat exchange pipe 10 according to needs, and all fall within the protection scope of the present invention.

[0087] Furthermore, a liquid replenishing pipe 113 is connected between the condenser 3 and the evaporator 5. A normally closed solenoid valve 15 is provided on the liquid replenishing pipe 113 to supplement the refrigerant required for lubrication from the condenser 3 to the evaporator 5 through the liquid replenishing pipe 113 when the refrigerant in the liquid bladder of the evaporator 5 is insufficient. The normally closed solenoid valve 15 closes when the unit is powered off. The condenser 3 and the subcooler 9 are connected through a balance pipe 114. One end of the balance pipe 114 is connected to the condenser 3, and the other end is connected to the subcooled liquid supply pipe 106, and the connection point is located between the second check valve 7 and the subcooler 9. A normally open solenoid valve 16 and a first check valve 17 are provided on the balance pipe 114. The normally open solenoid valve 16 opens when the unit is powered off (the normally open solenoid valve 16 closes during normal operation of the unit). The first check valve 17 only allows the refrigerant to flow from the condenser 3 towards the subcooler 9.

[0088] The high-pressure balance pipeline from the condenser 3 to the subcooler 9 is used to automatically keep the subcooler 9 at high pressure to continue supplying liquid for bearing lubrication during emergency power-off shutdown without any electrical control of the air-conditioning system. Specifically, after the unit is powered off, the normally open check valve 16 loses power and opens. At the initial stage of power-off, the pressure in the condenser is higher than that in the subcooler, and the first check valve 17 is pushed open. The high-pressure refrigerant gas enters the subcooler 9 from the condenser 3 through the balance pipe 114, forming a hydraulic pressure difference for bearing lubrication, and continues to provide lubrication for the bearing 2. When the condenser pressure drops to balance with the subcooler pressure, the condenser 3 no longer provides pressure. The first check valve 17 is used to prevent the pressure in the subcooler 9 from flowing back to the condenser 3 after the pressures of the condenser 3 and the subcooler 9 are balanced for a period of time after power-off, maintain the pressure in the subcooler 9, and continue to supply liquid for a period of time. After the supply pressure of the subcooler 9 decreases, the refrigerant stored in the liquid storage tank 211 continues to provide lubrication under the action of gravity. After power-off, lubrication is continuously provided for the bearing 2 through three liquid supply stages, making the lubrication time longer. Optionally, the subcooler 9 can also be arranged at a position higher than the bearing 2, so that the refrigerant liquid in the subcooler 9 flows from the subcooler 9 to the liquid storage tank 211 under its own weight to still provide long-term lubrication for the bearing 2 during power-off shutdown.

[0089] Furthermore, the condenser 3 and the centrifugal compressor 1 are connected through a motor cooling pipe 111, and the evaporator 5 and the centrifugal compressor 1 are connected through a return air pipe 112. The high-temperature liquid refrigerant after releasing heat at the condenser 3 cools the compressor motor through flash evaporation and absorption of heat, and then enters the evaporator 5 through the return air pipe 112.

[0090] A condenser pressure sensor 201 is provided on the condenser 3 to detect the condenser pressure. An evaporator pressure sensor 202 is provided on the evaporator 5 to detect the evaporator pressure. A refrigerant liquid level switch 203 is provided on the evaporator 5 to detect the refrigerant liquid level in the evaporator 5. A subcooler pressure sensor 204 and a subcooler temperature sensor 205 are provided on the subcooler 9 to detect the bearing lubrication liquid supply pressure P1 and the bearing lubrication liquid supply temperature T1. A bearing return liquid pressure sensor 206 is provided on the bearing return liquid pipe 108 to detect the bearing lubrication return liquid pressure P2. However, it should be noted that the present invention does not impose any restrictions on the installation positions of the above sensors, as long as the corresponding parameters can be detected, and they all fall within the protection scope of the present invention.

[0091] In addition, the pipelines in the air conditioning system of the present invention can be combined or split as needed. For example, one of the subcooling return liquid pipe 110 or the bearing return liquid pipe 108 can be combined with the return liquid pipe 109, or the return liquid pipe 109 can be cancelled, and the bearing return liquid pipe 108 and the subcooling return liquid pipe 110 can be directly connected to the evaporator 5 respectively, etc. Those skilled in the art can set according to needs, as long as the two components can be connected through pipelines and the corresponding functions can be realized, and any deformation of the pipeline connection structure falls within the protection scope of the present invention.

[0092] The detailed working process is as follows:

[0093] Refrigeration system: The high-temperature and high-pressure gaseous refrigerant compressed by the compressor 1 enters the condenser 3 through the exhaust pipe 101 and becomes a liquid refrigerant after heat exchange, then enters the economizer 4 through the liquid pipeline 102 for flash separation. The liquid at the bottom enters the evaporator 5 through the liquid inlet pipe 103, and the gaseous refrigerant at the upper part enters the compressor air inlet through the gas supply pipe 105. The liquid refrigerant entering the evaporator 5 through 103 absorbs heat in the evaporator 5 and becomes a gaseous refrigerant, which enters the return air port of the centrifugal compressor 1 through the suction pipe 104, completing the refrigeration cycle. The normally open solenoid valve 16 remains closed during the entire startup and operation of the unit.

[0094] Lubrication system: The fluorine pump 6 extracts liquid refrigerant from the liquid bag at the bottom of the evaporator 5 and transports it to the subcooler 9 through the cold liquid supply pipe 106. One of the liquid supply pipe branches 1061 of the cold liquid supply pipe 106 is connected to the heat exchange pipe 10. The refrigerant in the heat exchange pipe 10 flashes and absorbs heat after throttling by the electronic expansion valve 8, and cools the liquid refrigerant in the subcooler 9 to subcooled through the heat exchange pipe 10. The subcooled liquid refrigerant enters the compressor through the bearing liquid supply pipe 107, and the liquid is distributed to the liquid distribution ring 12 to lubricate the bearing 2. After lubrication, the flashed gas and the unflashed liquid both return to the evaporator 5 through the bearing liquid return pipe 108 and the liquid return pipe 109. The gas-liquid two-phase refrigerant that absorbs heat through the heat exchange pipe 10 also returns to the evaporator 5 through the subcooled liquid return pipe 110 and the liquid return pipe 109, completing the lubrication cycle.

[0095] Motor cooling system: The liquid refrigerant in the condenser 3 enters the motor through the motor cooling pipe 111, and the liquid and gaseous refrigerant after cooling the motor return to the evaporator 5 through the return air pipe 112, completing the motor cooling cycle.

[0096] Emergency shutdown of the unit when power is cut off: After the power grid is cut off, the unit loses power instantly. The compressor motor continues to run and decelerate under the action of inertia. The fluorine pump 6 stops rotating. The second one-way valve 7 closes under the action of the pressure difference. The normally closed solenoid valve 15 loses power and closes. The normally open solenoid valve 16 loses power and opens. When the pressure in the condenser 3 is higher than the pressure in the subcooler 9, the first one-way valve 17 is pushed open, and the high-pressure gaseous refrigerant enters the subcooler 9 from the condenser 3 through the balance pipe 114, forming a bearing liquid supply pressure difference to continue to provide bearing lubrication during the motor deceleration. When the pressure in the condenser 3 drops to balance with the pressure in the subcooler 9, the condenser 3 can no longer provide pressure, and the liquid stored in the liquid storage tank 211 on the bearing mounting seat 22 continues to supply liquid for lubrication under the action of gravity. Therefore, when the air-conditioning system is powered off, the refrigerant stored in the liquid storage tank 211 and the refrigerant in the subcooler 9 can jointly supply liquid for bearing lubrication under the action of the pressure in the condenser 3 to achieve the purpose of safe shutdown of the unit.

[0097] Before the unit starts: Before the air-conditioning centrifugal unit starts, the centrifugal compressor 1 is in the closed state. The liquid level switch 203 detects whether the liquid level in the liquid bag of the evaporator 5 reaches the height where the liquid level switch is installed and set. If the preset liquid level height is reached, the fluorine pump 6 is started after the unit is started to inject refrigerant into the liquid storage tank 211. If the preset liquid level height is not reached, the normally closed solenoid valve 15 is controlled to open, so that the liquid in the condenser 3 enters the liquid bag of the evaporator 5 through the liquid replenishing pipe 113 until the liquid level reaches the preset liquid level height, and then the normally closed solenoid valve 15 is controlled to lose power and close.

[0098] After the unit is started: after the liquid level in the evaporator 5 is sufficiently replenished, the centrifugal compressor 1 is controlled to start, and the fluorine pump 6 is turned on to supply liquid lubrication to the bearing 2. During the operation of the fluorine pump 6, the liquid level in the evaporator 5 is monitored in real time. Once the liquid level is lower than the preset liquid level, the normally closed solenoid valve 15 is controlled to open, and the timing is 30 seconds (variable according to the specific application). During the timing period, the fluorine pump 6 continues to run. If the liquid level returns to the preset liquid level within the timing time, the normally closed solenoid valve 15 is controlled to be closed. If the liquid level does not return to the preset liquid level within the timing time, the fluorine pump 6 is controlled to be closed and the centrifugal compressor 1 is shut down.

[0099] Although the air-conditioning system in the above-mentioned embodiment lubricates the bearing 2 by injecting refrigerant liquid into the liquid storage tank 211 through the bearing liquid supply pipe 107, those skilled in the art may also cancel the liquid separator ring 21 as needed, and the bearing liquid supply pipe 107 may directly pass the refrigerant liquid into the bearing 2 to lubricate the bearing 2, or connect a nozzle to the bearing liquid supply pipe 107 to spray lubricate the bearing 2, etc. Those skilled in the art may set the liquid supply method of the bearing 2 according to actual needs and all of them fall within the protection scope of the present invention.

[0100] Optionally, two liquid level switches 203 may be provided to detect high liquid level and low liquid level respectively. When the liquid level reaches above the high liquid level, the normally closed solenoid valve 15 is controlled to be closed; when the liquid level is between high and low, the normally closed solenoid valve 15 is controlled to be opened. When the liquid level is below the low level, the normally closed solenoid valve 15 remains open, and the fluorine pump 6 alarms but continues to run for 30 seconds (variable according to the specific application). When the liquid level reaches above the low level within the timing period, the alarm is lifted and the fluorine pump 6 continues to run. If the liquid level does not rise above the low level within the timing period, the fluorine pump 6 and the centrifugal compressor 1 are shut down to prevent damage to the bearing 2.

[0101] Furthermore, the present invention does not impose any restrictions on the type of the liquid level switch 203. For example, the liquid level switch 203 can also be changed to a liquid level gauge or other liquid level instruments. The control logic is similar to that of the high and low liquid level switches. As long as it can detect the liquid level of the refrigerant in the liquid capsule of the evaporator 5, those skilled in the art can set it as needed, and it falls within the protection scope of the present invention. In addition, the present invention does not impose any restrictions on the type of the normally closed solenoid valve 15. The normally closed solenoid valve 15 can also be a normally open solenoid valve or other types of valve bodies. Those skilled in the art can set the type of the second valve body (normally closed solenoid valve 15) as needed, as long as it can be opened and closed, and it falls within the protection scope of the present invention.

[0102] Reference Figure 7 , the specific steps of the control method of the air conditioning system are as follows:

[0103] Step S11: After receiving the signal to start the centrifugal compressor, the liquid level height in the evaporator liquid bag is obtained in real time;

[0104] Step S12: When the liquid level height in the evaporator liquid bag is less than the preset liquid level height, the normally closed solenoid valve is controlled to open;

[0105] Step S13: When the liquid level height in the evaporator liquid bag is greater than or equal to the preset liquid level height, the normally closed solenoid valve is controlled to close.

[0106] When the liquid level height in the evaporator liquid bag is greater than or equal to the preset liquid level height, step S14 is executed: Control the centrifugal compressor to start and control the fluorine pump to open;

[0107] While the fluorine pump 6 is running, steps S11 to S13 are executed. The control method further includes:

[0108] Step S15: When it is detected that the liquid level height in the evaporator liquid bag is less than the preset liquid level height, and after the normally closed solenoid valve has been opened for the first preset duration and the liquid level height in the evaporator liquid bag is still less than the preset liquid level height, the fluorine pump and the centrifugal compressor are controlled to close.

[0109] The controller obtains the value P1 of the subcooler pressure sensor 204, the value P2 of the bearing return liquid pressure sensor 206, and the value T1 of the subcooler temperature sensor 205. Generally, the differential pressure of the bearing oil supply △P = P1 - P2 = 2 - 4 bar (variable according to specific applications). The differential pressure is controlled by changing the rotational speed of the fluorine pump 6, such as changing the frequency of an AC motor or the pulse width modulation of a DC motor. For example, when the differential pressure △P is greater than the set differential pressure value, the rotational speed of the fluorine pump 6 is controlled to decrease, and when the differential pressure △P is less than the set differential pressure value, the rotational speed of the fluorine pump 6 is controlled to increase. At the same time, the saturation temperature T2 corresponding to the refrigerant used is calculated or obtained by looking up a table based on the pressure value P1. Generally, the subcooling degree △T of the refrigerant liquid = T2 - T1 = 3 - 5 °C (variable according to specific applications), and the subcooling degree of the liquid in the subcooler 9 is controlled by controlling the opening degree of the electronic expansion valve 8. For example, when the subcooling degree △T is greater than the set subcooling degree, the opening degree of the electronic expansion valve 8 is controlled to decrease, and when the subcooling degree △T is less than or equal to the set subcooling degree, the opening degree of the electronic expansion valve 8 is controlled to increase.

[0110] Refer to Figure 8 , the specific steps of the control method of the air conditioning system are as follows:

[0111] Step S21: Obtain the bearing lubrication oil supply pressure P1, the bearing lubrication return liquid pressure P2, and the bearing lubrication oil supply temperature T1;

[0112] Step S22: Calculate the bearing oil supply differential pressure △P = P1 - P2;

[0113] Step S23: Adjust the rotational speed of the fluorine pump according to the bearing oil supply differential pressure △P;

[0114] Step S24: Obtain the saturation temperature T2 corresponding to the refrigerant according to P1;

[0115] Step S25: Calculate the subcooling degree △T of the refrigerant, where △T = T2 - T1;

[0116] Step S26: Adjust the opening degree of the electronic expansion valve according to the subcooling degree △T.

[0117] Adjust the opening degree of the electronic expansion valve 8 through the subcooling degree, so that the subcooling degree is always maintained within the optimal range, which can not only reduce energy consumption, but also sufficiently cool the refrigerant, and prevent the refrigerant from flashing and vaporizing before entering the bearing to achieve the lubrication and cooling effects, thus affecting the lubrication effect.

[0118] The bearing liquid supply can be in the form of maintaining the pressure difference before and after, or in the form of a flow meter. The flow meter 10 is arranged on the bearing liquid supply pipe 107, and it is used to detect the actual bearing lubrication liquid supply flow rate. When using the flow meter, the pressure sensor 206 for monitoring the bearing return liquid pressure can be cancelled, and the bearing liquid supply is carried out according to the flow meter data. For example, the generally required liquid supply flow rate for bearing design is 2 liters per minute (variable according to specific applications). By adjusting the flow rate of the fluorine pump, the liquid supply flow rate is maintained, and thus the heat absorption capacity of the heat exchange pipe 10 is controlled.

[0119] The specific steps of the control method of the air-conditioning system are as follows:

[0120] Step: Obtain the value of the bearing lubrication liquid supply flow rate;

[0121] Step: Compare the obtained value of the bearing lubrication liquid supply flow rate with the required lubrication liquid supply volume for bearing design, and adjust the rotational speed of the fluorine pump accordingly.

[0122] When the actual bearing lubrication liquid supply flow rate value is higher than the required liquid supply volume for bearing design, the rotational speed of the fluorine pump is reduced; when the actual bearing lubrication liquid supply flow rate value is lower than the required liquid supply volume for bearing design, the rotational speed of the fluorine pump is increased, so that sufficient cooling refrigerant lubricates and cools the bearing 2.

[0123] As described in the first paragraph of this section, the above embodiments are only used to illustrate the principle of the present invention and are not intended to limit the protection scope of the present invention. Without departing from the principle of the present invention, those skilled in the art can adjust the above structure so that the present invention can be applied to more specific application scenarios.

[0124] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. An air conditioning system, characterized in that, The air conditioning system further includes a refrigerant circulation pipeline, on which a compressor, a condenser, and an evaporator are provided; the air conditioning system further includes a subcooler, which is connected to the evaporator through a subcooling liquid supply pipe, and is connected to the compressor through a bearing liquid supply pipe. A heat exchange pipe is arranged in the subcooler, and the heat exchange pipe is connected to the subcooling liquid supply pipe through a liquid supply pipe branch; a fluorine pump is arranged on the subcooling liquid supply pipe, a first valve body is arranged on the liquid supply pipe branch, and the compressor is connected to the evaporator through a bearing liquid return pipe; so that the refrigerant in the evaporator enters the subcooler and the heat exchange pipe respectively. Among them, the refrigerant that enters the heat exchange pipe after throttling by the first valve body absorbs the heat of the refrigerant in the subcooler. The subcooled refrigerant in the subcooler lubricates the bearing through the bearing liquid supply pipe, and the lubricated refrigerant returns to the evaporator through the bearing liquid return pipe.

2. The air conditioning system according to claim 1, characterized in that, The condenser and the subcooler are connected through a balance pipe, and a normally open solenoid valve is arranged on the balance pipe.

3. The air conditioning system according to claim 2, characterized in that, A first one-way valve is arranged on the balance pipe; and / or a second one-way valve is arranged on the subcooling liquid supply pipe.

4. The air conditioning system according to claim 1, characterized in that, The compressor is connected to the condenser through a motor cooling pipe, and the compressor is connected to the evaporator through a return air pipe, so that the refrigerant in the condenser cools the motor and then enters the evaporator through the return air pipe.

5. The air conditioning system according to any one of claims 1-4, characterized in that, A liquid replenishing pipe is connected between the condenser and the evaporator, and a second valve body is arranged on the liquid replenishing pipe.

6. The air conditioning system according to any one of claims 1-5, characterized in that, The air conditioning system includes an economizer, which is arranged on the pipeline between the condenser and the evaporator, and is connected to the compressor through a supplementary air pipe to supplement air to the compressor.

7. A control method for an air conditioning system, characterized in that, The air conditioning system further includes a refrigerant circulation pipeline, on which a compressor, a condenser, and an evaporator are provided; the air conditioning system further includes a subcooler, which is connected to the evaporator through a subcooling liquid supply pipe, and is connected to the compressor through a bearing liquid supply pipe. A heat exchange pipe is arranged in the subcooler, and the heat exchange pipe is connected to the subcooling liquid supply pipe through a liquid supply pipe branch; a fluorine pump is arranged on the subcooling liquid supply pipe, a first valve body is arranged on the liquid supply pipe branch, and the compressor is connected to the evaporator through a bearing liquid return pipe; so that the refrigerant in the evaporator enters the subcooler and the heat exchange pipe respectively. The refrigerant that enters the heat exchange pipe after throttling by the first valve body absorbs the heat of the refrigerant in the subcooler. The subcooled refrigerant in the subcooler lubricates the bearing through the bearing liquid supply pipe, and the lubricated refrigerant returns to the evaporator through the bearing liquid return pipe; The control method includes: Obtaining the bearing lubrication liquid supply pressure P1, the bearing lubrication liquid return pressure P2, and the bearing lubrication liquid supply temperature T1; Calculating the bearing liquid supply pressure difference △P = P1 - P2; Adjusting the rotation speed of the fluorine pump according to the bearing liquid supply pressure difference △P; Or, the control method includes: Obtaining the bearing lubrication liquid supply flow value; Adjust the rotational speed of the fluorine pump by comparing the bearing lubrication liquid supply flow value with the lubrication liquid supply required for bearing design.

8. The control method of the air conditioning system according to claim 7, wherein The control method includes: Calculate the saturation temperature T2 corresponding to the refrigerant according to P1; Calculate the subcooling degree △T of the refrigerant = T2 - T1; Adjust the opening degree of the first valve body according to the subcooling degree △T.

9. The control method of the air conditioning system according to claim 7, characterized in that, A liquid supplement pipe is connected between the condenser and the evaporator, and a second valve body is arranged on the liquid supplement pipe; The control method includes: After receiving the signal to start the compressor, obtain the liquid level height in the liquid bag of the evaporator; When the liquid level height in the liquid bag of the evaporator is less than the preset liquid level height, control the second valve body to open; When the liquid level height in the liquid bag of the evaporator is greater than or equal to the preset liquid level height, control the second valve body to close.

10. The control method of the air conditioning system according to claim 9, characterized in that, After the step of "when the liquid level height in the liquid bag of the evaporator is greater than or equal to the preset liquid level height, control the second valve body to close", the control method includes: Control the compressor to start and control the fluorine pump to start; When it is detected that the liquid level height in the liquid bag of the evaporator is less than the preset liquid level height, and after the second valve body has been opened for a first preset time period and the liquid level height in the liquid bag of the evaporator is still less than the preset liquid level height, control the fluorine pump and the compressor to close.

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