A series reverse step cooling type variable frequency magnetic suspension low temperature unit

Abstract

The present invention discloses a series reverse step cooling type variable frequency magnetic suspension cryogenic unit, which belongs to the field of compressors. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit includes a compressor, an evaporator, and a condenser; a plurality of magnetic suspension bearings are arranged in the compressor; a rotor is rotatably arranged on each magnetic suspension bearing; the rotor rotates in the compressor; the magnetic suspension bearing includes a bearing sleeve fixed in the compressor, an electromagnet evenly installed on the bearing sleeve along the circumferential direction, a driving mechanism arranged at both ends of the bearing sleeve axially, and a slide seat installed between the two driving mechanisms; a wiping belt for wiping the gap between the rotor and the bearing sleeve is rotatably connected to the slide seat. The magnet moves with the change of the magnetic field, so that the slide seat moves circumferentially along the bearing sleeve, and the wiping belt can wipe and remove dust from various positions on the magnetic suspension bearing.

Description

Technical Field

[0001] The present invention belongs to the field of compressors, and more specifically, relates to a series reverse step cooling type variable frequency magnetic suspension low temperature unit. Background Art

[0002] At present, the demand for energy-saving products of large commercial and industrial chillers is constantly increasing. There is no targeted high-efficiency product for the energy efficiency of low-temperature chillers in the pharmaceutical and chemical industry. At present, it is still a fixed-frequency low-temperature screw refrigeration unit, and the relevant national and industry standards are blank. However, under the national goal of energy conservation and emission reduction, high-energy consumption refrigeration units in the low-temperature pharmaceutical and chemical industry will gradually be eliminated by the market. By combining the most advanced permanent magnet variable frequency magnetic suspension technology with the reverse cascade cooling technology of heat exchangers in series, it can save more than 30% energy compared with the existing fixed-frequency low-temperature screw refrigeration units.

[0003] Among them, the permanent magnet variable frequency magnetic suspension technology is the use of magnetic suspension bearings in the compressor. The magnetic suspension bearing uses magnetic force to suspend the rotor in the air, so that there is no mechanical contact between the rotor and the stator. During the long-term use of the magnetic suspension bearing, dust and impurities will accumulate between the rotor and the stator, and then the dust and impurities will cause friction between the rotor and the stator, reducing the working efficiency and shortening the service life of the magnetic suspension bearing. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a series reverse step cooling type variable frequency magnetic suspension low temperature unit, which can clean the dust and impurities between the rotor and the stator and extend the life of the compressor.

[0005] The present invention discloses a series reverse step cooling type variable frequency magnetic suspension low temperature unit, comprising a compressor, an evaporator and a condenser; a plurality of magnetic suspension bearings are arranged in the compressor; a rotor is rotatably arranged on each magnetic suspension bearing; the rotor rotates in the compressor; the magnetic suspension bearing comprises a bearing sleeve fixed in the compressor, an electromagnet uniformly installed on the bearing sleeve along the circumferential direction, a driving mechanism arranged at both axial ends of the bearing sleeve, and a sliding seat installed between the two driving mechanisms; a wiping belt for wiping the gap between the rotor and the bearing sleeve is rotatably connected to the sliding seat.

[0006] As a further improvement of the present invention, the sliding seat is rotatably connected to two parallel rotating shafts; the rotating shafts of the rotating shafts are 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 periphery 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 ventilation mechanism installed at one end of the rotating ring away from the bearing sleeve; the sliding seat slides on the rotating ring radially along the bearing sleeve; and the bearing sleeve is provided with a groove for accommodating the sliding seat.

[0008] As a further improvement of the present invention, a magnet is provided on the rotating ring near the sliding seat; the magnet has a tendency to approach the electromagnet with the strongest magnetic field.

[0009] As a further improvement of the present invention, the ventilation mechanism includes an outer shell fixed on the bearing sleeve and a turntable sealed and rotated on one end of the outer shell close to the rotating ring; a partition coaxially arranged with the bearing sleeve is arranged on the turntable; the partition forms a first cavity and a second cavity that are not connected to each other in the outer shell; a cavity opening connecting the first cavity and the second cavity is arranged on the partition; a negative pressure pipe is arranged at a position on the partition opposite to the cavity opening; a negative pressure port connected to the negative pressure pipe is arranged at a position close to the wiping belt in the sliding seat.

[0010] As a further improvement of the present invention, a negative pressure cavity is arranged in the slide seat; the negative pressure port is arranged at a position of the negative pressure cavity close to the wiping belt; and a through port connected to the negative pressure tube is arranged on one side of the negative pressure cavity.

[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 a position in the outer shell near the cavity opening, and a reduction gear group transmission-connected to the impeller; a reduction gear group controls the radial sliding of the slide seat; and a reduction gear group is transmission-connected to the wiping belt.

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

[0013] As a further improvement of the present invention, a synchronous belt distributed radially along the bearing sleeve and drivingly connected to the wiping belt is installed on the sliding seat; a wiping gear meshing with the synchronous belt is rotatably connected to the rotating ring; and the wiping gear is drivingly connected to a reduction gear set.

[0014] As a further improvement of the present invention, the outer shell is provided with a first air pipe connected to the first cavity and a second air pipe connected to 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.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: this scheme controls the magnetic field enhancement of the local electromagnet to cause the rotor to deviate, so that a wiping space with a larger spacing is formed between the rotor and the electromagnet, thereby facilitating 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 circumferentially along the bearing sleeve, and the wiping belt can wipe and remove dust from various positions on the magnetic suspension bearing.

[0016] In this solution, the airflow generated by the air pump generates negative pressure in the negative pressure tube when the airflow passes through the cavity opening. The negative pressure absorbs the dust and impurities cleaned by the wiping belt and cleans them to the outside of the compressor, preventing the dust and impurities from accumulating in the magnetic bearing. At the same time, the airflow can also drive the impeller to rotate.

[0017] In this solution, the impeller rotates to drive the slide to slide radially, so that the slide leaves or enters the groove. When the slide is in the groove, the slide will not hinder the movement of the rotor. The impeller can also drive the wiping belt to wipe the magnetic bearing.

[0018] The magnetic bearing of this solution can autonomously clean the dust and impurities in the gap between the bearing sleeve and the rotor, and no additional power element is added to the magnetic bearing, that is, no additional power element is added to the compressor, and the structure of the original compressor is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0021] Figure 3 It is a schematic diagram of the exploded structure of the magnetic bearing of the present invention;

[0022] Figure 4 It is a schematic diagram of the exploded structure of the driving mechanism of the present invention;

[0023] Figure 5 It is a schematic cross-sectional structural diagram of the slide seat of the present invention;

[0024] Figure 6 It is a cross-sectional structural schematic diagram of the ventilation mechanism of the present invention;

[0025] Figure 7 It is a structural schematic diagram of the slide seat of the present invention when it moves from the receiving groove toward the rotor direction;

[0026] Figure 8 It is a structural schematic diagram of the present invention when the slide seat is located in the receiving groove;

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

[0028] Description of the numbers in the figure:

[0029] 11. compressor; 12. control panel; 13. magnetic bearing; 14. rotor; 2. bearing sleeve; 21. support block; 22. container groove; 23. wiping space; 3. electromagnet; 4. slide seat; 41. lifting rack; 42. synchronous belt; 43. negative pressure chamber; 431. negative pressure port; 44. wiping belt; 45. through port; 46. rotating shaft; 50. driving mechanism; 5. rotating ring; 51. magnet; 52. radial slide groove; 53. connecting hole; 60. ventilation mechanism; 6. outer shell; 61. first cavity; 62. second cavity; 63. first air pipe; 64. second air pipe; 7. turntable; 71. negative pressure pipe; 72. partition; 73. cavity opening; 81. impeller; 82. reduction gear set; 83. lifting gear; 84. wiping gear. DETAILED DESCRIPTION

[0030] Specific embodiment 1: Please refer to Figure 1-Figure 9 A series reverse step cooling type variable frequency magnetic suspension low temperature unit, comprising a compressor 11, an evaporator, and a condenser; a plurality of magnetic suspension bearings 13 are arranged in the compressor 11; a rotor 14 is rotatably arranged on each magnetic suspension bearing 13; the rotor 14 rotates in the compressor 11; the magnetic suspension bearing 13 comprises a bearing sleeve 2 fixed in the compressor 11, an electromagnet 3 uniformly installed on the bearing sleeve 2 along the circumferential direction, a driving mechanism 50 arranged at both axial ends of the bearing sleeve 2, and a slide seat 4 installed between the two driving mechanisms 50; a wiping belt 44 for wiping the gap between the rotor 14 and the bearing sleeve 2 is rotatably connected to the slide seat 4.

[0031] The magnetic bearing 13 further includes a plurality of sensors mounted on the bearing sleeve 2 ; the sensors are used to detect the current position of the rotor 14 , thereby facilitating controlling the position of the rotor 14 in the bearing sleeve 2 by changing the magnetic force of each electromagnet 3 .

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

[0033] The wiping drive belt is in driving connection with the rotating shaft 46 .

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

[0035] A support block 21 is disposed between the two electromagnets 3 on the bearing sleeve 2 ; the receiving groove 22 is disposed on one of the support blocks 21 ; when the slide seat 4 is located in the receiving groove 22 , the wiping belt does not contact the rotor 14 , thereby not hindering the rotation of the rotor 14 .

[0036] A magnet 51 is disposed on the rotating ring 5 near the slide seat 4 ; the magnet 51 has a tendency to approach the electromagnet 3 with the strongest magnetic field.

[0037] When the magnetic field generated by an electromagnet 3 is the largest, the repulsive force between the electromagnet 3 and the rotor 14 is also the largest, and then the rotor 14 will be located in an eccentric position, and the distance between the electromagnet 3 and the rotor 14 is the largest, forming a wiping space 23 that is easy to wipe, and 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 belt 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 controlled to decrease, the magnetic field of the next electromagnet 3 next to the electromagnet 3 will increase, so that the electromagnet 3 with the largest magnetic field will change, and then the magnet 51 will move in the direction of 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 approach the next electromagnet 3, changing the position of the slide 4, and the next electromagnet 3 has the largest magnetic field, so a wiping space 23 is formed between the next electromagnet 3 and the rotor 14.

[0039] The magnetic fields of the electromagnets 3 are controlled to change periodically, so that each electromagnet 3 becomes the electromagnet 3 with the largest magnetic field one by one. Then the rotating ring 5 rotates relative to the bearing sleeve 2 as the magnetic field changes, so that the slide seat 4 moves circumferentially along the bearing sleeve 2 to wipe each position on the magnetic suspension bearing 13.

[0040] The ventilation mechanism 60 includes an outer shell 6 fixed on the bearing sleeve 2, and a turntable 7 sealed and rotated on one end of the outer shell 6 close to the rotating ring 5; a partition 72 is arranged on the turntable 7 and is coaxially arranged with the bearing sleeve 2; the partition 72 forms a first cavity 61 and a second cavity 62 that are not connected to each other in the outer shell 6; the partition 72 is provided with a cavity opening 73 connecting the first cavity 61 and the second cavity 62; a negative pressure pipe 71 is arranged on the partition 72 at a position opposite to the cavity opening 73; a negative pressure port 431 connected to the negative pressure pipe 71 is arranged at a position close to the wiping belt 44 in the slide seat 4.

[0041] When gas flows between the first cavity 61 and the second cavity 62 , the flowing gas passes through the cavity opening 73 , thereby forming a negative pressure state at the position of the negative pressure tube 71 , so that negative pressure is formed at the negative pressure port 431 , and dust and impurities on the wiping belt 44 are sucked away.

[0042] A negative pressure chamber 43 is provided in the slide seat 4 ; the negative pressure port 431 is provided at a position of the negative pressure chamber 43 close to the wiping belt 44 ; and a through port 45 communicating with the negative pressure tube 71 is provided on one side of the negative pressure chamber 43 .

[0043] The rotating ring 5 is provided with a connecting hole 53 which is plugged into the negative pressure tube 71; the rotating ring 5 rotates synchronously with the turntable 7; the ventilation mechanism 60 also includes an impeller 81 rotatably connected to a position near the cavity opening 73 in the outer shell 6, and a reduction gear set 82 which is transmission-connected to the impeller 81; a reduction gear set 82 controls the radial sliding of the slide 4; and a reduction gear set 82 is transmission-connected to the wiping belt 44.

[0044] When air flows through the cavity opening 73 , the air drives the impeller 81 to rotate, thereby causing the reduction gear set 82 to work.

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

[0046] The slide seat 4 is provided with a synchronous belt 42 which is distributed radially along the bearing sleeve 2 and is transmission-connected to the wiping belt 44 ; the rotating ring 5 is rotationally connected with a wiping gear 84 which meshes with the synchronous belt 42 ; the wiping gear 84 is transmission-connected to a reduction gear set 82 .

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

[0048] The outer shell 6 is provided with a first air pipe 63 connected to the first cavity 61 and a second air pipe 64 connected to 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 works in the forward direction, the air pump blows air into the first air pipe 63 and draws air into the second air pipe 64; when the air pump works in the reverse direction, the air pump draws air into the first air pipe 63 and blows air into the second air pipe 64. By changing the working state of the air pump, the direction of the airflow at the position of the cavity opening 73 is changed, so as to control the rotation direction of the impeller 81.

[0050] The air pump is provided with filter cotton for filtering the cleaned dust and impurities to prevent the dust and impurities from returning to the compressor.

[0051] The low temperature unit further comprises a control panel 12; the control panel 12 is used to coordinate the work of various components.

[0052] Two compressors 11 are provided on the low-temperature unit. The compression type 11 is a large pressure ratio two-stage compression horizontally opposed permanent magnet variable frequency magnetic levitation oil-free compressor. The magnetic levitation bearing technology has no mechanical friction and does not require lubricating oil. The maximum speed is 8000RPM / min. The permanent magnet synchronous variable frequency motor saves 50% energy than ordinary AC fixed frequency motors. Each compressor adopts an independent oil-free refrigeration system, which improves the heat transfer efficiency by 20% compared with the traditional oil-containing refrigeration system.

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

[0054] In the initial state, the slide 4 is located in the receiving 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 in 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 size of each electromagnet 3, thereby ensuring that the rotor 14 is always coaxial with the bearing sleeve 2 during operation.

[0056] When the gap between the rotor 14 and the bearing sleeve 2 needs to be wiped, the magnetic field of the electromagnet 3 close to the groove 22 is first controlled to increase, and then the rotor 14 moves away from the groove 22, and a wiping space 23 is formed between the rotor 14 and the support block 21 corresponding to the groove 22.

[0057] Then the air pump works forward, blowing air into the first air pipe 63, the airflow enters the first cavity 61, and enters the second cavity through the cavity opening 73, and is finally sucked away by the air pump through the second air pipe 64; in this process, the airflow drives each impeller 81 to rotate forward, one impeller 81 drives the lifting gear 83 to rotate forward through the reduction gear set 82, and the lifting gear 83 drives the slide 4 to move toward 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, and the slide 4 cannot continue to move, and the corresponding impeller 81 stops rotating.

[0058] And the other impeller 81 drives the wiping gear 84 to rotate forward through the reduction gear set 82, and then the wiping belt 44 works through the transmission of the synchronous belt 42. The wiping belt 44 wipes the dust and impurities on the surface of the rotor 14, the electromagnet 3, and the support block 21, and the dust and impurities will move synchronously with the wiping belt 44.

[0059] When the airflow passes through the cavity opening 73, negative pressure is generated at the position of the negative pressure tube 71, and then the negative pressure port 431 connected thereto generates negative pressure synchronously. When the wiping belt 44 drives the dust and impurities to move near the negative pressure port 431, the dust and impurities will be attracted by the negative pressure, and then the dust and impurities pass through the negative pressure port 431, the negative pressure cavity 43, and the negative pressure tube 71 into the housing 6. Finally, under the action of the air pump, they leave the housing.

[0060] Then, the magnetic field of each electromagnet 3 changes periodically. Since the magnet 51 has a tendency to attract the position with the strongest magnetic field, the rotating ring 5 rotates with the change of the magnetic field, and then the slide 4 moves circumferentially along the bearing sleeve 2, wiping each position in the magnetic suspension bearing 13, and completely clearing the gap between the rotor 14 and the bearing sleeve 2.

[0061] After cleaning, the slide 4 is controlled to move to face the tank 22. Then the air pump works in reverse for a certain period of time, the impeller 81 rotates in the reverse direction, and then drives the lifting gear 83 to rotate in the reverse direction, and the lifting gear 83 drives the slide 4 back to the tank 22 to restore the initial state for the next use.

Claims

1. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit, characterized in that: It comprises a compressor, an evaporator and a condenser; a plurality of magnetic suspension bearings are arranged in the compressor; a rotor is rotatably arranged on each magnetic suspension bearing; the rotor rotates in the compressor; the magnetic suspension bearing comprises a bearing sleeve fixed in the compressor, an electromagnet evenly arranged on the bearing sleeve along the circumferential direction, a driving mechanism arranged at both ends of the bearing sleeve in the axial direction, and a slide seat arranged between the two driving mechanisms; a wiping belt for wiping the gap between the rotor and the bearing sleeve is rotatably connected to the slide seat; The driving mechanism comprises a rotating ring coaxially arranged with the bearing sleeve, and a venting mechanism installed at one end of the rotating ring away from the bearing sleeve; the sliding seat slides on the rotating ring along the radial direction of the bearing sleeve; and a groove for accommodating the sliding seat is arranged on the bearing sleeve; A magnet is arranged on the rotating ring near the sliding seat; the magnet has a tendency to approach the electromagnet with the strongest magnetic field; The ventilation mechanism comprises a shell fixed on the bearing sleeve, and a rotating disk sealed and rotating at one end of the shell near the rotating ring; a partition coaxially arranged with the bearing sleeve is arranged on the rotating disk; the partition forms a first cavity and a second cavity which are not connected to each other in the shell; a cavity opening connecting the first cavity and the second cavity is arranged on the partition; a negative pressure pipe is arranged at a position on the partition opposite to the cavity opening; a negative pressure port connected to the negative pressure pipe is arranged at a position near the wiping belt in the slide seat; The rotating ring rotates synchronously with the turntable; the ventilation mechanism also includes an impeller rotatably connected to a position in the shell near the cavity opening, and a reduction gear set transmission-connected to the impeller; a reduction gear set controls the radial sliding of the slide seat; and a reduction gear set is transmission-connected to the wiping belt.

2. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit according to claim 1, characterized in that: The slide seat is rotatably connected to two parallel rotating shafts; the rotating shafts of the rotating shafts are tangent to the circumference of the bearing sleeve; the wiping belt comprises a wiping driving belt sleeved between the two rotating shafts and a sponge belt fixed on the outer periphery of the wiping driving belt.

3. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit according to claim 1, characterized in that: A negative pressure cavity is arranged in the sliding seat; the negative pressure port is arranged at a position of the negative pressure cavity close to the wiping belt; and a through port communicating with the negative pressure pipe is arranged at one side of the negative pressure cavity.

4. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit according to claim 1, characterized in that: The slide seat is provided with a lifting rack distributed along the radial direction of the bearing sleeve; the rotating ring is rotatably connected with a lifting gear meshing with the lifting rack; the lifting gear is transmission-connected to a reduction gear set.

5. The series reverse step cooling type variable frequency magnetic suspension cryogenic unit according to claim 1 is characterized in that: The sliding seat is provided with a synchronous belt which is connected to the wiping belt and is distributed radially along the bearing sleeve; the rotating ring is rotatably connected with a wiping gear which is meshed with the synchronous belt; the wiping gear is connected to a reduction gear set.

6. A series reverse step cooling type variable frequency magnetic suspension cryogenic unit according to claim 1, characterized in that: The shell is provided with a first air pipe connected to the first cavity and a second air pipe connected to 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 connected to the first air pipe and the second air pipe respectively.

Images