Series reverse cascade cooling type variable-frequency magnetic suspension-based low-temperature unit

Abstract

The present invention relates to the field of compressors, and disclosed is a series reverse cascade cooling type variable-frequency magnetic suspension-based low-temperature unit. The series reverse cascade cooling type variable-frequency magnetic suspension-based low-temperature unit comprises compressors, an evaporator, and a condenser; a plurality of magnetic suspension bearings are arranged in each compressor; a rotor is rotatably arranged on each magnetic suspension bearing; the rotors rotate in the compressors; each magnetic suspension bearing comprises a bearing sleeve fixed in the corresponding compressor, electromagnets evenly mounted on the bearing sleeve in the circumferential direction, driving mechanisms arranged at two axial ends of the bearing sleeve, and a slide seat mounted between the two driving mechanisms; and a wiping belt for wiping a gap between the corresponding rotor and the corresponding bearing sleeve is rotatably connected to the slide seat. Magnets move in response to the change of a magnetic field, so that the slide seats move in the circumferential direction of the bearing sleeves, and the wiping belts can wipe dust away from different positions on the magnetic suspension bearings.

Description

A series reverse cascade cooling type variable frequency magnetic levitation cryogenic unit Technical Field

[0001] This invention belongs to the field of compressors, and more specifically, relates to a series reverse-stage cooling variable frequency magnetic levitation cryogenic unit. Background Technology

[0002] Currently, the demand for energy-efficient products in large commercial and industrial chillers is constantly increasing. However, the pharmaceutical and chemical industries lack targeted high-efficiency products for low-temperature chillers, and currently rely on fixed-frequency low-temperature screw chillers. There are also gaps in relevant national and industry standards. But under the national goals of energy conservation, emission reduction, and carbon reduction, high-energy-consuming chillers in the low-temperature pharmaceutical and chemical industries will gradually be phased out of the market. By combining the most advanced permanent magnet variable frequency magnetic levitation technology with series-connected reverse-stage cooling technology, energy savings of over 30% can be achieved compared to existing fixed-frequency low-temperature screw chillers.

[0003] The permanent magnet variable frequency magnetic levitation technology uses magnetic levitation bearings within the compressor. Magnetic levitation bearings utilize magnetic force to levitate the rotor in the air, eliminating mechanical contact between the rotor and stator. Over time, dust and impurities accumulate between the rotor and stator, causing friction and reducing efficiency, thus shortening the lifespan of the magnetic levitation bearings. Technical issues

[0004] The technical problem to be solved by the present invention is to provide a series reverse stepped cooling variable frequency magnetic levitation cryogenic unit, which can clean dust and impurities between the rotor and stator and extend the life of the compressor. Technical solutions

[0005] The present invention discloses a series reverse cascade cooling type variable frequency magnetic levitation cryogenic unit, comprising a compressor, an evaporator, and a condenser; the compressor is provided with multiple magnetic levitation bearings; each magnetic levitation bearing is rotatably mounted with a rotor; the rotor rotates within the compressor; each magnetic levitation bearing includes a bearing sleeve fixed within the compressor, electromagnets uniformly mounted circumferentially on the bearing sleeve, a drive mechanism disposed at both axial ends of the bearing sleeve, and a slide mounted between two drive mechanisms; a wiping strip for wiping the gap between the rotor and the bearing sleeve is rotatably connected to the slide.

[0006] As a further improvement of the present invention, the slide is rotatably connected to two parallel rotating shafts; the axis of rotation of the rotating shaft is tangent to the circumference of the bearing sleeve; the wiping belt includes a wiping drive belt sleeved between the two rotating shafts and a sponge belt fixed to the outer circumference of the wiping drive belt.

[0007] As a further improvement of the present invention, the driving mechanism includes a rotating ring coaxially arranged with the bearing sleeve and a venting mechanism installed at the end of the rotating ring away from the bearing sleeve; the slide slides radially on the rotating ring along the bearing sleeve; and the bearing sleeve is provided with a receiving groove for accommodating the slide.

[0008] As a further improvement of the present invention, a magnet is provided on the rotating ring near the slide; the magnet tends to move closer to the electromagnet with the strongest magnetic field.

[0009] As a further improvement of the present invention, the ventilation mechanism includes a housing fixed on a bearing sleeve and a rotating disk that is sealed and rotates at one end of the housing near the rotating ring; a partition plate coaxially arranged on the rotating disk is provided; the partition plate forms a first cavity and a second cavity that are not interconnected within the housing; a cavity opening connecting the first cavity and the second cavity is provided on the partition plate; a negative pressure pipe is provided on the partition plate opposite to the cavity opening; and a negative pressure port communicating with the negative pressure pipe is provided in the slide near the wiping belt.

[0010] As a further improvement of the present invention, a negative pressure chamber is provided inside the slide; the negative pressure port is located in the negative pressure chamber near the wiping belt; and a through-hole communicating with the negative pressure pipe is provided on one side of the negative pressure chamber.

[0011] As a further improvement of the present invention, the rotating ring rotates synchronously with the turntable; the ventilation mechanism also includes an impeller rotatably connected to the housing near the cavity opening, and a reduction gear set driven by the impeller; one reduction gear set controls the radial sliding of the slide; and one reduction gear set is driven by the wiping belt.

[0012] As a further improvement of the present invention, the slide is provided with a lifting rack distributed radially along the bearing sleeve; a lifting gear that meshes with the lifting rack is rotatably connected to the rotating ring; the lifting gear is connected to a reduction gear set for transmission.

[0013] As a further improvement of the present invention, a synchronous belt distributed radially along the bearing sleeve is installed on the slide block and is connected to the wiping belt for transmission; a wiping gear that meshes with the synchronous belt is rotatably connected to the rotating ring; and the wiping gear is connected to a reduction gear set for transmission.

[0014] As a further improvement of the present invention, the outer shell is provided with a first air pipe communicating with the first cavity and a second air pipe communicating with the second cavity; the first air pipe and the second air pipe extend to the outside of the compressor; an air pump is provided on one side of the compressor; the air pump is respectively connected to the first air pipe and the second air pipe. Beneficial effects

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This solution controls the enhancement of the magnetic field of the local electromagnet, causing the rotor to deviate, so that a wiping space with a large gap is formed between the rotor and the electromagnet, which facilitates the movement of the wiping belt in the wiping space. At the same time, by making the magnetic field of the electromagnet change periodically, the magnet moves with the change of the magnetic field, so that the slide moves along the circumference of the bearing sleeve, and the wiping belt can wipe and remove dust from various positions on the magnetic levitation bearing.

[0016] This solution uses airflow generated by an air pump to create negative pressure in the negative pressure pipe when the airflow passes through the cavity opening. The negative pressure adsorbs the dust and impurities cleaned by the wiping belt and removes them to the outside of the compressor, preventing dust and impurities from accumulating in the magnetic levitation bearing. At the same time, the airflow can also drive the impeller to rotate.

[0017] This design utilizes the rotation of the impeller to drive the slide to slide radially, allowing the slide to leave or enter the groove. When the slide is in the groove, it does not obstruct the movement of the rotor. It can also drive the wiping belt to wipe the magnetic levitation bearing.

[0018] The magnetic levitation bearing in this solution can autonomously clean the dust and impurities in the gap between the bearing sleeve and the rotor, and no additional power components are added to the magnetic levitation bearing. That is, no additional power components are added to the compressor, and the original compressor structure is not affected. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the structure of the present invention;

[0020] Figure 2 is a schematic diagram of the compressor of the present invention;

[0021] Figure 3 is an exploded structural diagram of the magnetic levitation bearing of the present invention;

[0022] Figure 4 is an exploded structural diagram of the driving mechanism of the present invention;

[0023] Figure 5 is a cross-sectional view of the slide of the present invention;

[0024] Figure 6 is a cross-sectional view of the ventilation mechanism of the present invention;

[0025] Figure 7 is a schematic diagram of the structure of the slide block of the present invention when it moves in the direction of the rotor within the self-contained groove.

[0026] Figure 8 is a schematic diagram of the structure of the present invention when the slide is located in the groove;

[0027] Figure 9 is a schematic diagram of the structure of the present invention when the slide is located in the wiping space.

[0028] Explanation of the labels in the diagram:

[0029] 11. Compressor; 12. Control panel; 13. Magnetic levitation bearing; 14. Rotor; 2. Bearing sleeve; 21. Support block; 22. Container groove; 23. Wiping space; 3. Electromagnet; 4. Slide; 41. Lifting rack; 42. Synchronous belt; 43. Negative pressure chamber; 431. Negative pressure port; 44. Wiping belt; 45. Through port; 46. Rotating shaft; 50. Drive mechanism; 5. Rotating ring; 51. Magnet; 52. Radial groove; 53. Connecting hole; 60. Ventilation mechanism; 6. Outer shell; 61. First chamber; 62. Second chamber; 63. First air pipe; 64. Second air pipe; 7. Turntable; 71. Negative pressure pipe; 72. Partition plate; 73. Chamber opening; 81. Impeller; 82. Reduction gear set; 83. Lifting gear; 84. Wiping gear. The best embodiment of the present invention

[0030] Specific Embodiment 1: Please refer to Figures 1-9 for a series reverse cascade cooling type variable frequency magnetic levitation cryogenic unit, including a compressor 11, an evaporator, and a condenser; the compressor 11 is provided with multiple magnetic levitation bearings 13; each magnetic levitation bearing 13 is rotatably mounted with a rotor 14; the rotor 14 rotates inside the compressor 11; the magnetic levitation bearing 13 includes a bearing sleeve 2 fixed inside the compressor 11, an electromagnet 3 evenly mounted on the bearing sleeve 2 circumferentially, a drive mechanism 50 set at both ends of the bearing sleeve 2 axially, and a slide 4 installed between two drive mechanisms 50; the slide 4 is rotatably connected with a wiping strip 44 for wiping the gap between the rotor 14 and the bearing sleeve 2.

[0031] The magnetic levitation bearing 13 also includes multiple sensors mounted on the bearing sleeve 2; the sensors are used to detect the current position of the rotor 14, thereby facilitating the control of the position of the rotor 14 within the bearing sleeve 2 by changing the magnetic force of each electromagnet 3.

[0032] The slide block 4 is rotatably connected to two parallel rotating shafts 46; the axis of rotation of the rotating shaft 46 is tangent to the circumference of the bearing sleeve 2; the wiping belt 44 includes a wiping drive belt sleeved between the two rotating shafts 46 and a sponge belt fixed to the outer circumference of the wiping drive belt.

[0033] The wiping drive belt is connected to the rotating shaft 46 for transmission.

[0034] The drive mechanism 50 includes a rotating ring 5 coaxially arranged with the bearing sleeve 2 and a ventilation mechanism 60 installed at the end of the rotating ring 5 away from the bearing sleeve 2; the slide 4 slides radially on the rotating ring 5 along the bearing sleeve 2; the bearing sleeve 2 is provided with a receiving groove 22 for accommodating the slide 4.

[0035] A support block 21 is provided on the bearing sleeve 2 between the two electromagnets 3; the receiving groove 22 is provided on a support block 21; when the slide 4 is located in the receiving groove 22, the wiping strip does not contact the rotor 14, and thus does not hinder the rotation of the rotor 14.

[0036] A magnet 51 is provided on the rotating ring 5 near the slide block 4; the magnet 51 tends to move closer to the electromagnet 3 with the strongest magnetic field.

[0037] When the magnetic field generated by an electromagnet 3 is at its maximum, the repulsive force between the electromagnet 3 and the rotor 14 is also at its maximum. Consequently, the rotor 14 will be located in an eccentric position, and the distance between the electromagnet 3 and the rotor 14 will be at its maximum, forming a wiping space 23 that is easy to wipe. At this time, the magnet 51 approaches the electromagnet 3 under the action of the magnetic field, so that the slide 4 is located in the wiping space 23, and the wiping strip 44 contacts the surface of the rotor 14, the surface of the electromagnet 3, and the surface of the support block 21.

[0038] If the magnetic field of the electromagnet 3 is reduced, the magnetic field of the next electromagnet 3 next to it will increase, causing the electromagnet 3 with the largest magnetic field to change. Then, the magnet 51 will move towards the next electromagnet 3 under the action of the magnetic field, that is, the rotating ring 5 will rotate and drive the slide 4 to move closer to the next electromagnet 3, changing the position of the slide 4. And because the next electromagnet 3 has the largest magnetic field, a wiping space 23 is formed between the next electromagnet 3 and the rotor 14.

[0039] By controlling the periodic changes in the magnetic field of each electromagnet 3, each electromagnet 3 becomes the electromagnet 3 with the largest magnetic field. As a result, the rotating ring 5 will rotate relative to the bearing sleeve 2 with the change in magnetic field, causing the slide 4 to move circumferentially along the bearing sleeve 2 and wipe various positions on the magnetic levitation bearing 13.

[0040] The ventilation mechanism 60 includes a housing 6 fixed to the bearing sleeve 2 and a turntable 7 that is sealed and rotated at one end of the housing 6 near the rotating ring 5. The turntable 7 is provided with a partition 72 coaxially arranged with the bearing sleeve 2. The partition 72 forms a first cavity 61 and a second cavity 62 that are not interconnected within the housing 6. The partition 72 is provided with a cavity opening 73 that connects the first cavity 61 and the second cavity 62. A negative pressure pipe 71 is provided on the partition 72 at a position opposite to the cavity opening 73. A negative pressure port 431 that communicates with the negative pressure pipe 71 is provided in the slide seat 4 near the wiping belt 44.

[0041] When there is gas flow between the first cavity 61 and the second cavity 62, the flowing gas will pass through the cavity opening 73, and thus a negative pressure state will be formed at the position of the negative pressure tube 71, so that a negative pressure will be formed at the negative pressure port 431, which will suck away the dust and impurities on the wiping belt 44.

[0042] The slide block 4 is provided with a negative pressure chamber 43; the negative pressure port 431 is located in the negative pressure chamber 43 near the wiping belt 44; and a through port 45 communicating with the negative pressure pipe 71 is provided on one side of the negative pressure chamber 43.

[0043] The rotating ring 5 is provided with a connection hole 53 for insertion into the negative pressure pipe 71; the rotating ring 5 rotates synchronously with the turntable 7; the ventilation mechanism 60 also includes an impeller 81 rotatably connected to the housing 6 near the cavity opening 73, and a reduction gear set 82 drivenly connected to the impeller 81; one reduction gear set 82 controls the radial sliding of the slide 4; one reduction gear set 82 is drivenly connected to the wiping belt 44.

[0044] When airflow passes through the cavity opening 73, the airflow drives the impeller 81 to rotate, which in turn causes the reduction gear set 82 to work.

[0045] The slide block 4 is provided with a lifting rack 41 that is radially distributed along the bearing sleeve 2; the rotating ring 5 is rotatably connected with a lifting gear 83 that meshes with the lifting rack 41; the lifting gear 83 is connected to a reduction gear set 82 for transmission.

[0046] The slide block 4 is equipped with a synchronous belt 42 that is radially distributed along the bearing sleeve 2 and is connected to the wiping belt 44 in a driving connection; the rotating ring 5 is rotatably connected with a wiping gear 84 that meshes with the synchronous belt 42; the wiping gear 84 is connected to a reduction gear set 82 in a driving connection.

[0047] The lifting gear 83 and the wiping gear 84 do not cooperate with the same reduction gear set 82.

[0048] The outer casing 6 is provided with a first air pipe 63 communicating with the first cavity 61 and a second air pipe 64 communicating with the second cavity 62; the first air pipe 63 and the second air pipe 64 extend to the outside of the compressor 11; an air pump is provided on one side of the compressor 11; the air pump is connected to the first air pipe 63 and the second air pipe 64 respectively.

[0049] When the air pump operates in the forward direction, it blows air into the first air pipe 63 and draws air into the second air pipe 64; when the air pump operates in the reverse direction, it draws air into the first air pipe 63 and blows air into the second air pipe 64. By changing the operating state of the air pump, the airflow direction at the cavity opening 73 is changed, making it easier to control the rotation direction of the impeller 81.

[0050] The air pump is equipped with a filter cotton to filter out the dust and impurities that are cleaned up, preventing the dust and impurities from returning to the compressor.

[0051] The cryogenic unit also includes a control panel 12; the control panel 12 is used to coordinate the operation of various components.

[0052] The cryogenic unit is equipped with two compressors 11. The compression type 11 is a high-pressure ratio two-stage compression horizontally opposed permanent magnet variable frequency magnetic levitation oil-free compressor. The magnetic levitation bearing technology eliminates mechanical friction and requires no lubrication. The maximum speed is 8000RPM / min. The permanent magnet synchronous variable frequency motor is 50% more energy-efficient than ordinary AC fixed frequency motors. Each compressor adopts an independent oil-free refrigeration system, which improves the heat transfer efficiency by 20% compared to traditional oil-containing refrigeration systems.

[0053] The unit's evaporator adopts a new type of falling film evaporator, which reduces the refrigerant charge by 50% compared to conventional flooded evaporators, saving unit costs and reducing the refrigerant's impact on the global greenhouse effect (GWP). The falling film evaporator can avoid the problems caused by liquid carrying in the suction of traditional flooded magnetic levitation centrifugal compressors, which can lead to compressor impeller impact and bearing displacement deviation. Compared with traditional flooded evaporators, the falling film evaporator reduces the static liquid column pressure drop loss and improves heat transfer efficiency by 15%.

[0054] In the initial state, the slide 4 is located in the groove 22, and the slide 4 will not move with the change of the magnetic field of the electromagnet 3.

[0055] When the rotor 14 rotates, the sensor detects the position of the rotor 14 inside the bearing sleeve 2. When it is detected that the position of the rotor 14 deviates from the axis of the bearing sleeve 2, the position of the rotor 14 is changed by changing the magnetic field magnitude of each electromagnet 3, so as to ensure that the rotor 14 is always coaxial with the bearing sleeve 2 during the operation.

[0056] When it is necessary to wipe the gap between the rotor 14 and the bearing sleeve 2, the magnetic field of the electromagnet 3 near the groove 22 is first increased, and then the rotor 14 moves away from the groove 22, forming a wiping space 23 between the rotor 14 and the support block 21 corresponding to the groove 22.

[0057] Next, the air pump operates in the forward direction, blowing air into the first air pipe 63. The airflow enters the first chamber 61, passes through the chamber opening 73 into the second chamber, and is finally drawn away by the air pump through the second air pipe 64. During this process, the airflow drives each impeller 81 to rotate in the forward direction. One impeller 81 drives the lifting gear 83 to rotate in the forward direction through the reduction gear set 82. The lifting gear 83 drives the slide 4 to move towards the rotor 14 through the lifting rack 41, and the slide 4 leaves the receiving groove 22. Finally, the wiping belt 44 abuts against the surface of the rotor 14. At this point, the slide 4 can no longer move, and the corresponding impeller 81 stops rotating.

[0058] Furthermore, another impeller 81 drives the wiping gear 84 to rotate forward through the reduction gear set 82, which in turn drives the wiping belt 44 through the synchronous belt 42. The wiping belt 44 removes dust and impurities from the surfaces of the rotor 14, electromagnet 3, and support block 21, and the dust and impurities move synchronously with the wiping belt 44.

[0059] When airflow passes through cavity opening 73, negative pressure is generated at the position of negative pressure pipe 71, which in turn generates negative pressure synchronously at negative pressure port 431. When the wiping belt 44 carries dust and impurities to the vicinity of negative pressure port 431, the dust and impurities are attracted by the negative pressure, and then enter the outer casing 6 through negative pressure port 431, negative pressure chamber 43, and negative pressure pipe 71. Finally, they leave the outer casing under the action of the air pump.

[0060] Then, the magnetic field of each electromagnet 3 changes periodically. Since the magnet 51 has the tendency to attract the position with the strongest magnetic field, the rotating ring 5 rotates with the change of magnetic field. Then, the slide 4 moves around the bearing sleeve 2 and wipes each position inside the magnetic levitation bearing 13, cleaning all the gaps between the rotor 14 and the bearing sleeve 2.

[0061] After cleaning, the slide 4 is moved to be directly aligned with the container 22. Then, the air pump operates in reverse for a certain period of time, causing the impeller 81 to rotate in reverse, which in turn drives the lifting gear 83 to rotate in reverse. The lifting gear 83 then drives the slide 4 back into the container 22, restoring its initial state for the next use.

Claims

1. A series reverse-stage cooling type variable frequency magnetic levitation cryogenic unit, characterized in that: The system includes a compressor, an evaporator, and a condenser; the compressor contains multiple magnetic levitation bearings; each magnetic levitation bearing has a rotor rotatably mounted on it; the rotor rotates within the compressor; each magnetic levitation bearing includes a bearing sleeve fixed within the compressor, electromagnets evenly mounted circumferentially on the bearing sleeve, drive mechanisms located at both axial ends of the bearing sleeve, and a slide mounted between two drive mechanisms; a wiping strip for wiping the gap between the rotor and the bearing sleeve is rotatably connected to the slide. The drive mechanism includes a rotating ring coaxially arranged with the bearing sleeve and a venting mechanism installed at the end of the rotating ring away from the bearing sleeve; the slide slides radially on the rotating ring along the bearing sleeve; the bearing sleeve is provided with a groove for accommodating the slide. A magnet is provided on the rotating ring near the slide block; the magnet tends to move closer to the electromagnet with the strongest magnetic field. The ventilation mechanism includes a housing fixed to a bearing sleeve and a rotating disk that is sealed and rotates at one end of the housing near the rotating ring. A partition plate coaxially arranged with the bearing sleeve is provided on the rotating disk. The partition plate creates two non-communicating cavities within the housing. An opening connecting the first and second cavities is provided on the partition plate. A negative pressure pipe is positioned on the partition plate opposite the cavity opening. A negative pressure port communicating with the negative pressure pipe is located within the slide block near the wiping belt. The rotating ring rotates synchronously with the turntable; the ventilation mechanism also includes an impeller rotatably connected inside the housing near the cavity opening, and a reduction gear set driven by the impeller; one reduction gear set controls the radial sliding of the slide; and one reduction gear set is driven by the wiping belt.

2. The series reverse-stage cooling variable frequency magnetic levitation cryogenic unit according to claim 1, characterized in that: The slide is rotatably connected to two parallel rotating shafts; the axis of rotation of the rotating shaft is tangent to the circumference of the bearing sleeve; the wiping belt includes a wiping drive belt sleeved between the two rotating shafts and a sponge belt fixed to the outer circumference of the wiping drive belt.

3. The series reverse-stage cooling variable frequency magnetic levitation cryogenic unit according to claim 1, characterized in that: The slide block is provided with a negative pressure chamber; the negative pressure port is located in the negative pressure chamber near the wiping belt; and a through-hole communicating with the negative pressure pipe is provided on one side of the negative pressure chamber.

4. The series reverse-stage cooling variable frequency magnetic levitation cryogenic unit according to claim 1, characterized in that: The slide is provided with a lifting rack distributed radially along the bearing sleeve; a lifting gear that meshes with the lifting rack is rotatably connected to the rotating ring; the lifting gear is connected to a reduction gear set for transmission.

5. The series reverse cascade cooling type variable frequency magnetic levitation cryogenic unit according to claim 1, characterized in that: A synchronous belt, radially distributed along the bearing sleeve, is mounted on the slide block and is connected to the wiping belt for transmission; a wiping gear that meshes with the synchronous belt is rotatably connected to the rotating ring; the wiping gear is connected to a reduction gear set for transmission.

6. The series reverse-stage cooling variable frequency magnetic levitation cryogenic unit according to claim 1, characterized in that: The outer casing is provided with a first air pipe communicating with a first cavity and a second air pipe communicating with a second cavity; the first air pipe and the second air pipe extend to the outside of the compressor; an air pump is provided on one side of the compressor; the air pump is connected to the first air pipe and the second air pipe respectively.

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