Labyrinth sealing component, centrifugal compressor, air conditioning device and control method of air conditioning device

Abstract

The invention relates to the technical field of labyrinth sealing components, particularly provides a labyrinth sealing component, a centrifugal compressor, an air conditioning device and a control method of the labyrinth sealing component, and aims to solve the problem that a labyrinth sealing component of an existing centrifugal compressor easily causes large leakage amount of a high-pressure refrigerant. In order to achieve the purpose, the labyrinth sealing component comprises an outer ring magnetic unit, an inner ring magnetic unit corresponding to the outer ring magnetic unit and a labyrinth sealing unit capable of being adjusted in a radial telescopic mode, a labyrinth sealing structure is arranged on the labyrinth sealing unit, and the inner ring magnetic unit is connected with the labyrinth sealing unit. The inner ring magnetic unit can be driven by the magnetic force of the outer ring magnetic unit to drive the labyrinth sealing unit to stretch out and draw back in the radial direction. The magnetic force pushes or pulls the inner ring magnetic force unit to move, then the labyrinth sealing unit is driven to integrally stretch out and draw back in the radial direction, due to the fact that the electromagnetic force is easier to control and stable, the sealing gap between the sealing teeth and the impeller of the whole sealing unit can be more accurately controlled, and refrigerant leakage is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of labyrinth seal components, and particularly provides a labyrinth seal component, a centrifugal compressor, an air-conditioning device and a control method thereof. Background Art

[0002] In the air-conditioning industry, water-cooled units using centrifugal compressors are an important part of large air conditioners. Centrifugal refrigeration compressors usually use labyrinth seal components to prevent communication between the high-pressure area at the exhaust end of the impeller and the low-pressure area at the intake end. The advantage of labyrinth seals is that they are non-contact, with a theoretically infinite lifespan, simple structure and low cost. The high-pressure refrigerant gas compressed by the impeller flows from the high-pressure side through the gap between the impeller and the labyrinth seal teeth to the low-pressure area. The gas entering from the high-pressure side forms a turbulent flow in the gap and is rectified under the action of the pressure difference and then enters the next-stage seal teeth, and finally flows to the low-pressure area, resulting in leakage. Although a pressure difference is formed between each stage of teeth, reducing the gas leakage amount, generally the leakage amount of this type of seal accounts for at least about 1.5%-3% of the total exhaust volume of the compressor. When the number of seal teeth is not less than 6, the influence of the number of teeth becomes very small. Therefore, the size of the leakage amount is mainly determined by the sealing gap between the seal teeth and the impeller. However, when the sealing gap is set too small, the impeller runout will wear the tooth tips, thereby expanding the gap, which in turn increases the leakage amount and causes unnecessary energy loss.

[0003] Correspondingly, there is a need in the art for a new seal component to solve the problem that the labyrinth seal component of the existing centrifugal compressor is prone to a large amount of high-pressure refrigerant leakage. Summary of the Invention

[0004] The present invention aims to solve the above technical problems, that is, to solve the problem that the labyrinth seal component of the existing centrifugal compressor is prone to a large amount of high-pressure refrigerant leakage.

[0005] In a first aspect, the present invention provides a labyrinth seal component, which includes an outer ring magnetic force unit, an inner ring magnetic force unit corresponding to the outer ring magnetic force unit, and a radially telescopic and adjustable labyrinth seal unit. A labyrinth seal structure is provided on the labyrinth seal unit. The inner ring magnetic force unit is connected to the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially.

[0006] In the case of adopting the above technical solution, the labyrinth seal unit is set to be telescopically adjustable in the radial dimension, so that the labyrinth seal unit expands or contracts integrally relative to the axis to adjust the size of the seal gap between the end of the seal teeth and the surface of the sealed part, thereby ensuring that the seal gap is always at the optimal seal size, retaining the advantages of the non-contact labyrinth seal and ensuring the minimum refrigerant leakage. The inner ring magnetic unit is pushed or pulled to move by the attractive or repulsive magnetic force between the outer ring magnetic unit and the inner ring magnetic unit, and then drives the labyrinth seal unit to expand or contract radially as a whole. Since the magnetic force is easier to control and stable, the seal gap between the circumferential seal teeth of the entire seal unit and the impeller can be controlled more precisely.

[0007] In addition, since the present invention can adjust the size of the seal gap by controlling the magnetic force, when the load of the air conditioner unit is low to the compressor surge zone, the seal gap can be increased by control, so as to increase the amount of gas flowing from the high-pressure area on the exhaust side of the impeller to the low-pressure area on the suction side of the impeller, avoid the compressor from entering the surge state, and the unit does not need to be provided with a hot gas bypass separately, reducing costs and structural complexity.

[0008] In the optional technical solution of the above labyrinth seal component, the labyrinth seal unit includes a plurality of labyrinth seal modules, and telescopic connection structures are arranged at the head and tail ends of the labyrinth seal modules, and a plurality of the labyrinth seal modules are connected end to end through the telescopic connection structures to form a closed loop.

[0009] In the case of adopting the above technical solution, compared with directly setting the material of the labyrinth seal unit to a flexible and telescopic material, such as rubber or silica gel, etc., and using its own elasticity to perform telescopic diameter change, although the telescopic effect can be achieved through the elasticity of the material itself, the density between the seal teeth will change, resulting in poor sealing effect. By connecting the labyrinth seal modules end to end through the telescopic connection structure, the density change between the seal teeth can be minimized to ensure the sealing effect.

[0010] In the optional technical solution of the above labyrinth seal component, the telescopic connection structure includes a plugging tooth and a plugging groove that cooperate with each other to slide, and the plugging tooth and the plugging groove are arranged at the head and tail ends of the labyrinth seal module; alternatively, the telescopic connection structure includes an elastic member, and the labyrinth seal modules are connected end to end through the elastic member.

[0011] In the case of adopting the above technical solution, when subjected to the magnetic force, the plugging tooth slides in the plugging groove or the elastic member expands or contracts, so that the labyrinth seal unit expands or contracts radially, and when it expands or contracts, the density increase between the seal teeth is minimized as much as possible to ensure the sealing effect.

[0012] In an alternative technical solution of the above labyrinth seal member, the labyrinth seal member further includes a housing, the housing is provided with a receiving cavity extending radially by a certain depth, the outer ring magnetic force unit is connected to the inner wall of the receiving cavity, and the inner ring magnetic force unit is arranged in the receiving cavity and can slide radially along the inner wall of the receiving cavity when subjected to magnetic force.

[0013] In the case of adopting the above technical solution, the sliding of the inner ring magnetic force unit in the receiving cavity can ensure the stability when adjusting the seal gap.

[0014] In an alternative technical solution of the above labyrinth seal member, the labyrinth seal member further includes a sealing ring, a sealing groove is provided on the inner wall of the receiving cavity, the sealing ring is arranged in the sealing groove, and the sealing ring is located between the inner wall of the receiving cavity and the inner ring magnetic force unit; and / or, a distance sensor is provided on the housing.

[0015] In the case of adopting the above technical solution, since a small amount of high-pressure refrigerant will enter the gap between the pressing plate and the housing under the action of pressure, the sealing ring can prevent the refrigerant in the high-pressure area from flowing into the low-pressure area along the gap, improving the sealing performance, and a distance sensor is provided on the housing to detect the size of the seal gap.

[0016] In an alternative technical solution of the above labyrinth seal member, the housing further includes a housing body and a pressing plate, the pressing plate is detachably connected to the housing body, the housing body and the pressing plate jointly form the receiving cavity, and the sealing groove is provided on the housing body.

[0017] In the case of adopting the above technical solution, the detachable connection between the pressing plate and the housing body can facilitate the installation of the sealing ring.

[0018] In an alternative technical solution of the above labyrinth seal member, at least one of the outer ring magnetic force unit and the inner ring magnetic force unit is an electromagnet; and / or, the circumferential extension shapes of the inner ring magnetic force unit and the outer ring magnetic force unit are annular, the inner ring magnetic force unit is connected along the outer circumference of the labyrinth seal unit, and the labyrinth seal structure is arranged on the inner circumference of the labyrinth seal unit.

[0019] In the case of adopting the above technical solution, the characteristics of generating magnetism by energizing the electromagnet can accurately control the direction and magnitude of the magnetic force, which is convenient for adjustment. The circumferential extension shapes of the inner ring magnetic force unit and the outer ring magnetic force unit being annular can realize the pushing and pulling of each labyrinth seal module.

[0020] The present invention also provides a centrifugal compressor, the centrifugal compressor includes an impeller and the labyrinth seal member according to any one of the above technical solutions, and the labyrinth seal unit is sleeved on the impeller to seal the impeller.

[0021] The present invention further provides an air-conditioning device, which includes the labyrinth seal member described in any one of the above technical solutions.

[0022] The present invention further provides a control method for an air-conditioning device. The air-conditioning device includes a centrifugal compressor, the centrifugal compressor includes an impeller and a labyrinth seal member. The labyrinth seal member includes an outer ring magnetic force unit, an inner ring magnetic force unit corresponding to the outer ring magnetic force unit, and a radially telescopic and adjustable labyrinth seal unit. A labyrinth seal structure is arranged on the labyrinth seal unit. The inner ring magnetic force unit is connected to the labyrinth seal unit. The inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially; the labyrinth seal unit is sleeved on the impeller to seal the impeller.

[0023] The control method includes:

[0024] Judging whether the centrifugal compressor surges;

[0025] When the centrifugal compressor surges, controlling the inner ring magnetic force unit to move radially until the seal gap is a first set distance;

[0026] When the centrifugal compressor does not surge, controlling the inner ring magnetic force unit to move radially until the seal gap is a second set distance; wherein, the second set distance < the first set distance.

[0027] In the case of adopting the above technical solutions, when the centrifugal compressor surges, the labyrinth seal unit is controlled to move radially to increase the seal gap, so as to increase the leakage of the refrigerant from the high-pressure side to the low-pressure side to avoid surging. When the compressor operates normally, the seal gap is reduced, thereby reducing the refrigerant leakage and improving the operation energy efficiency.

[0028] In the optional technical solution of the above labyrinth seal member, the step of "judging whether the centrifugal compressor surges" further includes:

[0029] Detecting the ratio of the exhaust pressure to the suction pressure during the operation of the centrifugal compressor, that is, the pressure ratio;

[0030] When the pressure ratio is higher than the compressor surge calculation value, it indicates entering the surge zone;

[0031] When the pressure ratio is lower than the compressor surge calculation value, it indicates not entering the surge zone.

[0032] In the case of adopting the above technical solutions, by detecting the pressure ratio to judge whether the compressor surges, since it combines the parameters of the exhaust pressure and the suction pressure, the accuracy of surge judgment is improved.

[0033] Solution 1. A labyrinth seal member, characterized in that it includes an outer ring magnetic force unit, an inner ring magnetic force unit arranged corresponding to the outer ring magnetic force unit, and a labyrinth seal unit that can be adjusted radially and telescopically. The labyrinth seal unit is provided with a labyrinth seal structure. The inner ring magnetic force unit is connected to the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially.

[0034] Solution 2. The labyrinth seal member according to Solution 1, characterized in that the labyrinth seal unit includes a plurality of labyrinth seal modules. Telescopic connection structures are provided at the head and tail ends of the labyrinth seal modules, and a plurality of the labyrinth seal modules are connected end to end through the telescopic connection structures to form a closed loop.

[0035] Solution 3. The labyrinth seal member according to Solution 2, characterized in that the telescopic connection structure includes a plug tooth and a plug slot that cooperate with each other to slide, and the plug tooth and the plug slot are arranged at the head and tail ends of the labyrinth seal module; alternatively, the telescopic connection structure includes an elastic member, and the labyrinth seal modules are connected end to end through the elastic member.

[0036] Solution 4. The labyrinth seal member according to any one of Solutions 1-3, characterized in that the labyrinth seal member further includes a housing. The housing is provided with a receiving cavity extending radially to a certain depth. The outer ring magnetic force unit is connected to the inner wall of the receiving cavity, and the inner ring magnetic force unit is arranged in the receiving cavity and can slide radially along the inner wall of the receiving cavity when subjected to magnetic force.

[0037] Solution 5. The labyrinth seal member according to Solution 4, characterized in that the labyrinth seal member further includes a sealing ring. A sealing groove is provided on the inner wall of the receiving cavity, and the sealing ring is arranged in the sealing groove. The sealing ring is located between the inner wall of the receiving cavity and the inner ring magnetic force unit; and / or, a distance sensor is provided on the housing.

[0038] Solution 6. The labyrinth seal member according to Solution 5, characterized in that the housing further includes a housing body and a pressing plate. The pressing plate is detachably connected to the housing body, and the housing body and the pressing plate jointly form the receiving cavity. The sealing groove is provided on the housing body.

[0039] Solution 7. The labyrinth seal member according to any one of Solutions 1-6, characterized in that at least one of the outer ring magnetic force unit and the inner ring magnetic force unit is an electromagnet; and / or, the circumferential extension shapes of the inner ring magnetic force unit and the outer ring magnetic force unit are annular. The inner ring magnetic force unit is connected along the outer circumference of the labyrinth seal unit, and the labyrinth seal structure is arranged on the inner circumference of the labyrinth seal unit.

[0040] Solution 8. A centrifugal compressor, characterized in that the centrifugal compressor includes an impeller and the labyrinth seal member according to any one of Items 1-7 above, and the labyrinth seal unit is sleeved on the impeller so as to seal the impeller.

[0041] Solution 9. An air conditioning device, characterized in that the air conditioning device includes the labyrinth seal member according to any one of Claims 1-7.

[0042] Solution 10. A control method for an air conditioning device, characterized in that the air conditioning device includes a centrifugal compressor, the centrifugal compressor includes an impeller and a labyrinth seal member, the labyrinth seal member includes an outer ring magnetic force unit, an inner ring magnetic force unit correspondingly arranged with the outer ring magnetic force unit, and a radially telescopic and adjustable labyrinth seal unit, a labyrinth seal structure is arranged on the labyrinth seal unit, the inner ring magnetic force unit is connected with the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to telescopically move in the radial direction; the labyrinth seal unit is sleeved on the impeller so as to seal the impeller;

[0043] The control method includes:

[0044] Judging whether the centrifugal compressor has surge;

[0045] When the centrifugal compressor has surge, controlling the inner ring magnetic force unit to move in the radial direction until the seal gap is a first set distance;

[0046] When the centrifugal compressor does not have surge, controlling the inner ring magnetic force unit to move in the radial direction until the seal gap is a second set distance; wherein, the second set distance < the first set distance.

[0047] Solution 11. The control method for the air conditioning device according to Solution 10, characterized in that the step of "judging whether the centrifugal compressor has surge" further includes:

[0048] Detecting the ratio of the exhaust pressure to the suction pressure during the operation of the centrifugal compressor, i.e., the pressure ratio;

[0049] When the pressure ratio is higher than the compressor surge calculation value, it indicates entering the surge zone;

[0050] When the pressure ratio is lower than the compressor surge calculation value, it indicates not entering the surge zone.

[0051] Those skilled in the art can understand that the labyrinth seal member of the present invention includes an outer ring magnetic force unit, an inner ring magnetic force unit arranged corresponding to the outer ring magnetic force unit, and a radially telescopic adjustable labyrinth seal unit. A labyrinth seal structure is provided on the labyrinth seal unit. The inner ring magnetic force unit is connected to the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially.

[0052] In the case of adopting the above technical solution, the labyrinth seal unit is set to be telescopically adjustable in radial dimension, so that the labyrinth seal unit expands or contracts integrally relative to the axis to adjust the size of the seal gap between the end of the seal tooth and the surface of the sealed part, thereby ensuring that the seal gap is always in the optimal seal size. It not only retains the advantages of non-contact labyrinth seals but also can ensure the minimum refrigerant leakage to improve the operating efficiency of the unit. The inner ring magnetic force unit is pushed or pulled to move by the attractive magnetic force or repulsive magnetic force between the outer ring magnetic force unit and the inner ring magnetic force unit, and then drives the labyrinth seal unit to expand and contract radially as a whole. Since the magnetic force is easier to control and stable, the seal gap between the circumferential seal teeth of the entire seal unit and the impeller can be controlled more precisely.

[0053] In addition, since the present invention can adjust the size of the seal gap by controlling the magnetic force, when the load of the air-conditioning unit is low to the compressor surge zone, the seal gap can be increased by control to increase the amount of gas flowing from the high-pressure area on the exhaust side of the impeller to the low-pressure area on the suction side of the impeller, avoiding the compressor from entering the surge state. The unit does not need to be equipped with a hot gas bypass separately, simplifying the structures such as the electric valve, pipeline, and silencer configured for anti-surge, reducing costs and structural complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

[0055] Figure 1 is a three-dimensional structure diagram of the labyrinth seal unit of the present invention;

[0056] Figure 2 is a three-dimensional structure diagram of the labyrinth seal module of the present invention;

[0057] Figure 3 is a three-dimensional structure diagram of the labyrinth seal module of the present invention;

[0058] Figure 4 is a front view of the labyrinth seal member of the present invention;

[0059] Figure 5 is Figure 4 a cross-sectional view taken along line A-A in

[0060] Figure 6It is a cross-sectional view after the assembly of the centrifugal compressor impeller and the labyrinth seal member of the present invention;

[0061] Figure 7 is Figure 6 an enlarged view of part I in

[0062] Figure 8 It is a step flowchart of the control method of the air-conditioning device of the present invention.

[0063] List of reference numerals:

[0064] 1. Labyrinth seal member; 11. Outer ring magnetic unit; 12. Inner ring magnetic unit; 13. Labyrinth seal unit; 131. Labyrinth seal module; 132. Seal teeth; 1311. Insertion teeth; 1312. Insertion slots; 14. Outer shell body; 141. Accommodation cavity; 142. Pressure plate; 151. First seal groove; 152. Second seal groove; 153. Sealing ring; 16. Distance sensor;

[0065] 2. Impeller; 3. Housing. Detailed implementation manners

[0066] The preferred implementation manners of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners 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 make adjustments according to needs to adapt to specific application scenarios. For example, although this application is described in combination with the centrifugal compressor of a centrifugal chiller for air conditioning, this is not restrictive. The labyrinth seal member of the present invention can be applied not only to the seal of the centrifugal compressor of the air-conditioning device, but also to other positions that need to be sealed in the air-conditioning device. Or, the labyrinth seal member of the present invention can also be applied to other types of air-conditioning devices, and can also be applied to other devices that need to be sealed such as steam turbines and gas turbines other than air conditioners.

[0067] It should be noted that in the description of the present invention, terms indicating directions or positional relationships such as "center", "left", "right", "vertical", "inner", "outer", 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.

[0068] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, 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 components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0069] Referring to Figure 5 , to solve the problem that the labyrinth seal component of the existing centrifugal compressor is prone to large leakage of high-pressure refrigerant, the labyrinth seal component of the present invention includes an outer ring magnetic force unit 11, an inner ring magnetic force unit 12 corresponding to the outer ring magnetic force unit 11, and a labyrinth seal unit 13. The labyrinth seal unit 13 is arranged to be radially telescopically adjustable. At least one of the outer ring magnetic force unit 11 and the inner ring magnetic force unit 12 is an electromagnet. The labyrinth seal unit 13 is provided with a labyrinth seal structure. The inner ring magnetic force unit 12 is connected to the labyrinth seal unit 13, and the inner ring magnetic force unit 12 can drive the labyrinth seal unit 13 to telescopically move radially under the magnetic force drive of the outer ring magnetic force unit 11.

[0070] The advantages of the above setting method are as follows: The labyrinth seal unit 13 is arranged to be telescopically adjustable in the radial dimension, so that the labyrinth seal unit 13 can be expanded or contracted as a whole relative to the axis to adjust the size of the seal gap between the end of the seal tooth 132 and the surface of the sealed part, thereby ensuring that the seal gap is always in the best sealing size, retaining the advantages of non-contact labyrinth seals and ensuring the minimum refrigerant leakage. Secondly, at least one of the outer ring magnetic force unit 11 and the inner ring magnetic force unit 12 is an electromagnet. By passing an electric current through the electromagnet, a magnetic force is generated between the two magnetic force units. The inner ring magnetic force unit 12 is pushed or pulled to move through the attractive magnetic force or repulsive magnetic force between the outer ring magnetic force unit 11 and the inner ring magnetic force unit 12, and then drives the labyrinth seal unit 13 to telescopically move radially as a whole. Since the electromagnetic force is easier to control and stable, the seal gap between the circumferential seal teeth 132 of the entire seal unit and the impeller 2 can be controlled more precisely.

[0071] In addition, since the present invention can adjust the size of the seal gap by controlling the magnetic force, when the load of the air-conditioning unit is low to the compressor surge zone, the seal gap can be increased by control, so as to increase the amount of gas flowing from the high-pressure area on the exhaust side of the impeller 2 to the low-pressure area on the suction side of the impeller 2, avoiding the compressor from entering the surge state. The unit does not need to be provided with a hot gas bypass separately, simplifying the structures such as the electric valve, pipeline, and muffler configured for anti-surge, and reducing the cost and structural complexity.

[0072] Referring to Figure 4 and Figure 5, In a possible implementation, the labyrinth seal member 1 is annular, which includes a housing, an outer ring magnetic force unit 11, an inner ring magnetic force unit 12, and a labyrinth seal unit 13. The housing includes a housing body 14 and a pressing plate 142. The cross-section of the housing body 14 is L-shaped, and the housing body 14 and the pressing plate 142 are detachably connected. For example, they are connected by bolts or glued together, etc. The housing body 14 and the pressing plate 142 together form a receiving cavity 141 with a cross-section similar to a U-shape. The receiving cavity 141 extends a certain depth in the radial direction and is arranged in a ring along the circumference of the housing body 14. The outer ring magnetic force unit 11, the inner ring magnetic force unit 12, and part of the labyrinth seal unit 13 are arranged in the receiving cavity 141. The outer ring magnetic force unit 11 is fixedly connected to the top inner wall of the receiving cavity 141. The inner ring magnetic force unit 12 and part of the labyrinth seal unit 13 can radially expand and contract and slide along the inner wall of the receiving cavity 141 when the inner ring magnetic force unit 12 is subjected to magnetic force.

[0073] Optionally, the outer ring magnetic force unit 11 is set as an electromagnet, and the inner ring magnetic force unit 12 is set as a permanent magnet. By adjusting the current direction applied to the outer ring magnetic force unit 11, the magnetic pole of the outer ring magnetic force unit 11 is changed. When the magnetic poles of the inner and outer ring magnets are the same, the magnetic force direction is to push the inner ring magnetic force unit 12 to move radially inward. When the magnetic poles of the inner and outer ring magnets are opposite, the magnetic force direction is to pull the inner ring magnetic force unit 12 to move radially outward. The magnetic force magnitude can also be adjusted by controlling the current magnitude. The longer the power-on time, the greater the moving distance of the inner ring magnetic force unit 12.

[0074] Referring to Figures 1 to 3 , Further, the labyrinth seal unit 13 includes four labyrinth seal modules 131. The inner circumference of the labyrinth seal module 131 is provided with seal teeth 132. The head and tail ends of the labyrinth seal module 131 are provided with insertion teeth 1311 and insertion slots 1312, so that the plurality of labyrinth seal modules 131 are inserted end to end to form a closed ring. The insertion teeth 1311 and the insertion slots 1312 can slide relative to each other along the circumference. Referring to Figure 5 , The inner circumference of the inner ring magnetic force unit 12 is connected to the outer circumference of the labyrinth seal unit 13, and the outer circumference of the outer ring magnetic force unit 11 is connected to the inner wall of the housing. When subjected to magnetic force, the insertion teeth 1311 slide in the insertion slots 1312, so that the labyrinth seal unit 13 expands and contracts radially. When it expands and contracts, it tries to reduce the increase in the density between the seal teeth 132 to ensure the sealing effect. When the sealing gap ( Figure 7 D2 in Figure 7in D1), so as to be able to provide an adjustment amount for the outward movement of the inner ring magnetic force unit 12. After the inner ring magnetic force unit 12 drives the labyrinth seal unit 13 to shrink in place as a whole, the seal gap reaches the set size, and the inner ring magnetic force unit 12 stops moving, and relies on the frictional force between the inner ring magnetic force unit 12 and the labyrinth seal unit 13 and the inner wall of the accommodation cavity 141 to keep the position fixed. Or, in another possible implementation manner, a retractable limiting structure may also be provided on the inner wall of the accommodation cavity 141. The limiting structure may be a limiting post. After the seal gap is adjusted in place, the limiting post extends out from the inner wall of the accommodation cavity 141 and inserts into the limiting hole on the seal unit 13 or the inner ring magnetic force unit 12 to limit the sliding of the labyrinth seal unit 13. Those skilled in the art can set the fixing manner of the labyrinth seal unit 13 in the accommodation cavity 141 according to needs, and all fall within the protection scope of the present invention.

[0075] It should be noted that the retractable connection structure is not limited to the matching structure of the insertion slot and the insertion tooth. The retractable connection structure can also be an elastic member. An elastic member is connected between the labyrinth seal modules 131, and the elastic member is used to realize the telescopic diameter change of the labyrinth seal unit 13 by the expansion and contraction of the elastic member. The elastic member can be a spring, a rubber elastic body, a corrugated pipe, etc. Those skilled in the art can set the specific structure of the retractable connection structure according to needs. Compared with directly setting the material of the labyrinth seal unit 13 into a flexible and retractable material, such as rubber or silica gel, etc., and using its own elasticity to perform telescopic diameter change, although the telescopic effect can be achieved by the elasticity of the material itself, the density between the seal teeth 132 will change, resulting in poor sealing effect. The number of the labyrinth seal modules 131 can be set to 2, 3, 5, 6, etc. according to needs in addition to 4. Those skilled in the art can set the number of the labyrinth seal modules 131 according to needs, and all fall within the protection scope of the present invention.

[0076] It should also be noted that although the circumferential extension shapes of the outer peripheral magnetic force unit 11, the inner ring magnetic force unit 12, and the accommodation cavity 141 are described as closed rings, those skilled in the art can set their shapes according to needs. The circumferential extension shape can be not only a closed circular ring, so as to be able to push and pull the labyrinth seal unit 13 in all directions, but also the closed ring can be replaced with an unclosed ring according to needs, and the circumferential extension shapes of the inner ring magnetic force unit 12, the outer peripheral magnetic force unit 11, and the accommodation cavity 141 are set to segmented circular arcs to form an unclosed ring. The number of arc segments corresponds to the number of the labyrinth seal modules 131, and the length of the arc segment is less than the length of the labyrinth seal module 131, so as to save material costs. The present invention does not impose any restrictions on the circumferential extension shapes of the outer peripheral magnetic force unit 11, the inner ring magnetic force unit 12, and the accommodation cavity 141, and all fall within the protection scope of the present invention.

[0077] Reference Figure 7 , the labyrinth seal member 1 further includes a sealing ring 153. First sealing grooves 151 and second sealing grooves 152 are respectively arranged on the left and right inner walls of the accommodation cavity 141. The sealing ring 153 is respectively arranged in the first sealing groove 151 and the second sealing groove 152. The first sealing groove 151 is arranged on the housing body 14 and is located between the inner wall of the housing body 14 and the inner ring magnetic force unit 12. The second sealing groove 152 is arranged on the pressing plate 142 and is located between the inner wall of the pressing plate 142 and the inner ring magnetic force unit 12. Since a small amount of high-pressure refrigerant will enter the gap between the pressing plate 142 and the housing under pressure, the sealing rings 153 in the left first sealing groove 151 and the second sealing groove 152 can prevent the refrigerant in the high-pressure area from flowing into the low-pressure area along the gap, improving the sealing performance.

[0078] Reference Figure 7 , further, the labyrinth seal member 1 further includes a distance sensor 16. In a possible implementation manner, the distance sensor 16 can be directly arranged on the labyrinth seal unit 13 to directly detect the size of the sealing gap. During the debugging stage, the sealing gap is a relatively large value to avoid the wear of the sealing tooth ends when the impeller 2 jumps. For example, the initial sealing gap is 2 mm. When actually operating the compressor, the labyrinth seal unit 13 is controlled to move downward so that the sealing gap is always maintained at 0.05 - 0.15 mm, effectively reducing the leakage amount during operation and improving the compressor efficiency by about 1%. In another possible implementation manner, the distance sensor 16 is arranged on the pressing plate 142, and it is used to detect the distance between the distance sensor 16 and the rotating surface of the impeller 2 ( Figure 7In D3), when the impeller 2 rotates, there is a radial runout. The distance between the distance sensor 16 and the impeller 2 is calculated when the radial runout is the largest. Based on this distance, the clearance between the sealing teeth 132 and the impeller 2 is converted, and then the magnetic force is used to push the labyrinth seal unit 13 to adjust the sealing clearance, leaving a safety distance of 0.05 - 0.15 mm as the sealing clearance. For example, the sealing clearance, the distance between the distance sensor 16 and the rotating surface of the impeller can all be obtained through measurement. For instance, the initial distance from the top of the sealing tooth to the distance sensor 16 is 2 mm, that is, the radius value of the top of the sealing tooth is 2 mm smaller than the radius value of the distance sensor, and the distance between the distance sensor 16 and the rotating surface of the impeller is 3.0 mm. During the actual radial runout of the compressor impeller 2, the minimum distance between the distance sensor 16 and the impeller 2 is 2.9 mm, and the ideal sealing clearance is set to 0.1 mm. Therefore, the labyrinth seal unit 13 is controlled to move downward by 0.8 mm (2.9 - 2 - 0.1 = 0.8 mm) to make the sealing clearance reach 0.1 mm. Those skilled in the art can set the number and installation position of the distance sensors 16 as needed, as long as the sealing clearance size can be obtained from the distance values detected by the distance sensors 16, and all fall within the protection scope of the present invention.

[0079] It should also be noted that although the detachable connection between the pressing plate 142 and the housing body 14 is more convenient for the installation of the sealing ring 153, those skilled in the art can also fixedly connect the pressing plate 142 to the housing body 14 or integrally form them. For example, direct die-casting, welding, or stamping forming, etc. Or, those skilled in the art can also cancel the pressing plate 142 as needed, directly press the side wall of the housing body 14 against the housing 3 of the centrifugal compressor, and the housing 3 of the centrifugal compressor and the housing body 14 jointly form the accommodation cavity 141. Those skilled in the art can set it as needed, and all fall within the protection scope of the present invention.

[0080] In addition, those skilled in the art can also set the inner ring magnetic unit 12 as an electromagnet and the outer ring magnetic unit 11 as a permanent magnet according to needs, or set both the outer ring magnetic unit 11 and the inner ring magnetic unit 12 as electromagnets. Of course, the types of magnets of the outer ring magnetic unit 11 and the inner ring magnetic unit 12 can be set by those skilled in the art as needed, as long as the outer ring magnetic unit 11 can drive the inner ring magnetic unit 12 to move, and all fall within the protection scope of the present invention. Furthermore, in addition to the vertical sealing teeth 132, the labyrinth seal structure can also be a honeycomb structure, a labyrinth structure, a stepped structure, etc. Those skilled in the art can set the specific form of the labyrinth seal structure as needed, and the present invention does not impose any restrictions on the specific structural form of the labyrinth seal structure and all fall within the protection scope of the present invention.

[0081] In addition, the present invention further provides an air conditioning device, specifically a centrifugal chiller for air conditioners. The air conditioning device includes a centrifugal compressor, an evaporator, and a condenser. The evaporator, the condenser, and the centrifugal compressor are all arranged on the refrigerant circulation loop. A circulating chilled water circuit is connected to the evaporator, and the chilled water exchanges heat with the evaporator. A circulating cooling water circuit is connected to the condenser, and the cooling water exchanges heat with the condenser. The refrigerant circulates between the evaporator and the condenser through the refrigerant circulation loop. During use, the user can control the operation of the air conditioning device by setting the temperature, and the indoor environment is cooled or heated by the heat exchange between the chilled water or the cooling water and the indoor environment. Of course, the present invention does not impose any restrictions on the specific connection structure of the air conditioning device. For example, the air conditioning device can be a centrifugal air-cooled unit, replacing the water circuit with an air circuit, and the indoor environment is cooled or heated by the heat exchange between the air circuit and the evaporator or the condenser. Or, those skilled in the art can also cancel the chilled water circuit and the cooling water circuit in the air conditioning device, but instead arrange the evaporator and the condenser indoors and outdoors respectively, and the indoor heat exchange is carried out through the refrigerant circulation. Those skilled in the art can set the connection structure of the air conditioning device according to needs, and all fall within the protection scope of the present invention.

[0082] Referring to Figure 6 , further, the centrifugal compressor includes a labyrinth seal member 1, an impeller 2, and a housing 3. A refrigerant high-pressure area and a low-pressure area are formed between the impeller 2 and the housing 3. When the centrifugal compressor operates normally, the impeller 2 rotates at a high speed, and the gaseous refrigerant in the low-pressure area is sucked in and driven to rotate together. Under the action of centrifugal force, the gaseous refrigerant is thrown towards the impeller outlet. After being compressed and doing work by the impeller 2, a high-pressure area is formed at the outlet. The labyrinth seal unit 13 is sleeved on the impeller 2 to seal the impeller 2 and prevent the refrigerant in the high-pressure area from flowing back into the low-pressure area.

[0083] The sealing gap between the sealing teeth 132 and the impeller 2 can be adjusted according to actual needs, which can effectively reduce the leakage amount during operation. The smaller the sealing gap, the less the leakage amount. For example, the sealing gap is 0.05 - 0.15 mm. Optionally, the sealing gap is 0.06 mm, 0.07 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.14 mm, etc. Although the present invention gives examples of the sealing gap, it is not intended to impose any restrictions on the sealing gap. Those skilled in the art can set the sealing gap according to needs, and all fall within the protection scope of the present invention.

[0084] When the air-conditioning load is as low as the surge region, in order to prevent the compressor from surging at low loads, the existing common practice is to add a connecting pipe between the condenser and the evaporator. There is an adjustable electric valve on the connecting pipe. By controlling the opening of the electric valve, the amount of gas flowing back from the condenser to the evaporator is adjusted to avoid compressor surging, which is usually called hot gas bypass. However, it not only has a complex structure but also cannot accurately control the amount of gas flowing back. It cannot effectively solve the surging problem and may also reduce the energy efficiency of the air-conditioning unit.

[0085] When the air-conditioning load decreases and it is detected that the centrifugal compressor is surging or about to surge, the air-conditioning device of the present invention can control the inner ring magnetic unit 12 to move radially outward to approach the outer ring magnetic unit 11, so as to increase the sealing gap between the end of the sealing tooth 132 and the impeller 2, enabling more refrigerant in the high-pressure area to flow to the low-pressure area. This can not only avoid the compressor from entering the surging state but also control the size of the sealing gap according to the degree of surging to reduce surging. There is no need to separately set up a hot gas bypass for the unit, thus simplifying the structure.

[0086] Refer to Figure 8 , the control method of the air-conditioning device includes:

[0087] Step S10: Determine whether the centrifugal compressor surges;

[0088] Step S20: When the centrifugal compressor surges, control the inner ring magnetic unit to move radially outward until the gap between the end of the sealing tooth and the impeller is a first set distance, so as to increase the refrigerant leakage amount to avoid surging;

[0089] Step S30: When the centrifugal compressor does not surge, control the inner ring magnetic unit to move radially inward until the gap between the end of the sealing tooth and the impeller is a second set distance; wherein, the second set distance < the first set distance, so as to reduce the refrigerant leakage amount and improve the compressor efficiency.

[0090] There are many ways to determine whether the centrifugal compressor surges. For example, it can be determined by detecting the vibration frequency during the operation of the centrifugal compressor. When the vibration frequency of the compressor increases significantly, it indicates that the compressor surges. Or it can also be determined by detecting the ratio of the discharge pressure to the suction pressure, that is, the pressure ratio, to determine whether it enters the surging state. When the pressure ratio is higher than the calculated value of the compressor surge, it enters the surging area, and it is necessary to increase the gap to increase the gas reflux between high and low pressures to reduce the pressure ratio and keep the pressure ratio lower than the set value of the surging area. Specifically, step S10 further includes:

[0091] Step: Detect the ratio of the discharge pressure to the suction pressure during the operation of the centrifugal compressor;

[0092] Step: When the pressure ratio is higher than the calculated value of the compressor surge, it indicates that the centrifugal compressor enters the surging area.

[0093] When the pressure ratio is higher than the surge calculation value, it is necessary to increase the seal clearance to increase the gas reflux between the high and low pressures and reduce the pressure ratio, so that the pressure ratio remains lower than the set value in the surge zone.

[0094] Steps: When the pressure ratio is lower than the surge calculation value of the compressor, it means that the centrifugal compressor has not entered the surge zone.

[0095] The pressure ratio is used to judge whether the compressor enters surge. Since it combines the values of the exhaust pressure and the suction pressure for judgment, the judgment accuracy of the compressor entering the surge zone is improved. Of course, the detection method of the centrifugal compressor surge is not limited to the above embodiments. It can also judge the surge by monitoring the exhaust pulsation or the pressure change value of the compressor. Those skilled in the art can set the detection method of the compressor surge according to needs, as long as it can judge whether the compressor enters surge. The present invention does not make any restrictions on this and all fall within the protection scope of the present invention.

[0096] In summary, the labyrinth seal member 1 of the present invention can be magnetically telescopically variable in diameter, and then control the seal clearance between the end seal teeth 132 and the impeller 2. It can not only maintain the advantages of the non-contact labyrinth seal structure being simple and having a long service life, but also minimize the refrigerant leakage to improve the operation efficiency of the unit; and the centrifugal compressor provided with the labyrinth seal member 1 can also avoid surge by precisely increasing the seal clearance, without the need to separately set a reflux device, simplifying the structures such as the electric valve, pipeline, and silencer configured for surge prevention.

[0097] 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 structures so that the present invention can be applied to more specific application scenarios.

[0098] So far, the technical solutions of the present invention have been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand 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. A labyrinth seal member, characterized in that, It includes an outer ring magnetic force unit, an inner ring magnetic force unit arranged corresponding to the outer ring magnetic force unit, and a labyrinth seal unit that can be adjusted radially and telescopically. A labyrinth seal structure is provided on the labyrinth seal unit. The inner ring magnetic force unit is connected to the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially.

2. The labyrinth seal member according to claim 1, wherein, The labyrinth seal unit includes a plurality of labyrinth seal modules. Telescopic connection structures are provided at the head and tail ends of the labyrinth seal modules. Through the telescopic connection structures, the plurality of labyrinth seal modules are connected end to end to form a closed loop.

3. The labyrinth seal member according to claim 2, wherein The telescopic connection structure includes a plugging tooth and a plugging groove that cooperate with each other to slide. The plugging tooth and the plugging groove are arranged at the head and tail ends of the labyrinth seal module; alternatively, the telescopic connection structure includes an elastic member, and the labyrinth seal modules are connected end to end through the elastic member.

4. The labyrinth seal member according to any one of claims 1-3, characterized in that, The labyrinth seal member further includes a housing. The housing is provided with a receiving cavity extending a certain depth in the radial direction. The outer ring magnetic force unit is connected to the inner wall of the receiving cavity, and the inner ring magnetic force unit is arranged in the receiving cavity and can slide radially along the inner wall of the receiving cavity when subjected to magnetic force.

5. The labyrinth seal member according to claim 4, wherein, The labyrinth seal member further includes a sealing ring. A sealing groove is provided on the inner wall of the receiving cavity. The sealing ring is arranged in the sealing groove, and the sealing ring is located between the inner wall of the receiving cavity and the inner ring magnetic force unit; and / or, a distance sensor is provided on the housing.

6. The labyrinth seal member according to claim 5, wherein The housing further includes a housing body and a pressing plate. The pressing plate is detachably connected to the housing body. The housing body and the pressing plate jointly form the receiving cavity, and the sealing groove is provided on the housing body.

7. The labyrinth seal member according to any one of claims 1-6, characterized in that, At least one of the outer ring magnetic force unit and the inner ring magnetic force unit is an electromagnet; and / or, the circumferential extension shapes of the inner ring magnetic force unit and the outer ring magnetic force unit are annular. The inner ring magnetic force unit is connected along the outer circumference of the labyrinth seal unit, and the labyrinth seal structure is arranged on the inner circumference of the labyrinth seal unit.

8. A centrifugal compressor, characterized in that, The centrifugal compressor includes an impeller and the labyrinth seal member according to any one of claims 1-7. The labyrinth seal unit is sleeved on the impeller to seal the impeller.

9. An air-conditioning device, characterized in that, The air conditioning device includes the labyrinth seal member according to any one of claims 1-7.

10. A control method for an air conditioning device, characterized in that, The air conditioning device includes a centrifugal compressor. The centrifugal compressor includes an impeller and a labyrinth seal member. The labyrinth seal member includes an outer ring magnetic force unit, an inner ring magnetic force unit arranged corresponding to the outer ring magnetic force unit, and a labyrinth seal unit that can be adjusted radially and telescopically. A labyrinth seal structure is provided on the labyrinth seal unit. The inner ring magnetic force unit is connected to the labyrinth seal unit, and the inner ring magnetic force unit can be driven by the magnetic force of the outer ring magnetic force unit to drive the labyrinth seal unit to expand and contract radially; the labyrinth seal unit is sleeved on the impeller to seal the impeller; The control method includes: Judging whether the centrifugal compressor has a surge; When surge occurs in the centrifugal compressor, control the inner ring magnetic unit to move radially until the sealing gap is a first set distance; When surge does not occur in the centrifugal compressor, control the inner ring magnetic unit to move radially until the sealing gap is a second set distance; wherein, the second set distance < the first set distance.

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