High-stability permanent magnet direct drive motor of screw pump

Abstract

The application discloses a high-stability permanent magnet direct-drive motor of a screw pump, which comprises a shell, a cover detachably fixed to one end of the shell, a water cooling ring coaxially fixed in the shell, a stator installed in the shell and coaxially fixed in the water cooling ring, wherein a coil winding is arranged on the stator, a rotor rotatably installed in the shell, bearings installed on the other end of the shell and the cover, and the inner rings of the bearings fixed to the two ends of the rotor, and a connecting shaft rotatably connected to one end of the screw pump and connected with a main shaft of the screw pump, wherein the other end of the connecting shaft is connected with the rotor. The segmented structure of the rotor in the application can combine the elastic deformation of the segmented rotor, supporting springs and torsional springs, effectively absorb and buffer the increased torque and axial impact energy, avoid the huge mechanical stress caused by rigid connection, protect the motor, the connecting shaft and the pump body itself, and enhance the stability of the system.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet motor technology, specifically a high-stability permanent magnet direct drive motor for screw pumps. Background Technology

[0002] In screw pumps, the direct-drive motor is directly connected to the pump's drive shaft, converting electrical energy into mechanical energy. Traditional technologies use rigid couplings for direct connection. However, during startup, the medium resistance and pressure changes are prone to sudden shifts, generating extremely high instantaneous torque and axial force. This impact is directly transmitted to the motor bearings, shaft, and permanent magnets, easily leading to overload shutdowns or component damage. Furthermore, traditional cooling methods, such as fixed-flow water cooling or simple air cooling, allow the pump to operate at full power under low loads and low motor heat generation, wasting significant pumping energy. Under high loads, however, the heat generation increases dramatically, and the fixed cooling capacity is insufficient to suppress the temperature rise, leading to winding overheating (insulation aging), permanent magnet demagnetization, and permanent performance degradation.

[0003] Therefore, it is necessary to provide a highly stable permanent magnet direct drive motor for screw pumps to solve the problems mentioned in the background art. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a high-stability permanent magnet direct-drive motor for a screw pump, comprising:

[0005] The housing has an end cap that is detachably fixed to one end;

[0006] The water-cooling ring is coaxially fixed inside the housing.

[0007] The stator is installed inside the housing and coaxially fixed in the water-cooling ring, and the stator is provided with coil windings;

[0008] The rotor is rotatably mounted inside the housing. Bearings are installed on the other end of the housing and on the end cover. The two ends of the rotor are respectively fixed to the inner rings of the bearings.

[0009] A connecting shaft is rotatably connected to one end of the screw pump and connected to the main shaft of the screw pump; the other end of the connecting shaft is connected to the rotor.

[0010] Furthermore, as a preferred embodiment, an oil sealing ring is fixed inside the housing between the rotor and the stator, a front sealing plate is fixed at one end of the water cooling ring near the end cover, and a rear sealing plate is fixed at the other end of the water cooling ring, with the front sealing plate and the rear sealing plate respectively sealingly assembled with the two ends of the oil sealing ring.

[0011] Both the front and rear sealing discs are provided with multiple ventilation holes. The end of the housing near the rear sealing disc is equipped with a tail cover, and a dustproof heat dissipation cover is installed on the outside of the tail cover.

[0012] Furthermore, as a preferred embodiment, the sidewall of the water-cooling ring has two annular grooves symmetrically opened at both ends, and a plurality of axially arranged axial flow channels are distributed circumferentially between the two annular grooves. The sidewall of the housing is provided with a liquid inlet hole and a liquid outlet hole, and the liquid inlet hole and the liquid outlet hole are respectively connected to the two annular grooves.

[0013] Furthermore, preferably, the gaps between each of the axial flow channels and the coil windings are connected accordingly, and multiple flow holes are equidistantly distributed on the side wall of the water-cooling ring and within the axial flow channels.

[0014] Furthermore, a collar is coaxially and slidably installed on the inner wall of the water-cooling ring, and the side wall of the collar is provided with through holes corresponding to each of the flow holes;

[0015] A thrust plate is axially slidably installed inside the housing near the end cover, and the thrust plate is fixed coaxially with the collar.

[0016] Furthermore, as a preferred embodiment, each of the sidewalls of the water-cooling ring is provided with a flow-stopping insert at the drain end of each axial flow channel, and each flow-stopping insert is radially sealed and slidably assembled on the water-cooling ring, with a wedge-shaped inclined surface at the lower end of each flow-stopping insert.

[0017] The outer wall of the end of the collar is provided with a chamfer, and the collar is pressed into contact with the flow stop insert through the chamfer.

[0018] Furthermore, as a preferred embodiment, a liquid guide plate is slidably and sealed on the same side of the rear sealing plate within the housing. The rear sealing plate has multiple drainage holes, each of which is connected to the liquid guide plate. An inner channel is provided on the tail cover, with one end of the inner channel connected to the liquid guide plate and the other end of the inner channel connected to the drainage hole.

[0019] Furthermore, preferably, the rotor includes:

[0020] A rotating shaft with a rotor core mounted on its outside, and multiple permanent magnets distributed circumferentially on the rotor core;

[0021] A sliding shaft is slidably connected to one end of the rotating shaft near the end cover, and the thrust disc is mounted on the sliding shaft via a bearing;

[0022] A fixed bushing has one end fixed to a connecting shaft, and one end of the sliding shaft extends into and is connected to the fixed bushing. The outer peripheral wall of the sliding shaft has two centrally symmetrical oblique notches, and the fixed bushing has arc-shaped flanges corresponding to the oblique notches. Each arc-shaped flange is in sliding contact with the oblique notch.

[0023] Furthermore, as a preferred embodiment, the sliding shaft and the fixed bushing are rotatably assembled, and a rotational gap is provided between them, and a torsion spring is provided between the sliding shaft and the fixed bushing.

[0024] Furthermore, as a preferred embodiment, a support spring is connected between the sliding shaft and the rotating shaft, and the sliding shaft slides away from the rotating shaft by the elastic force of the support spring.

[0025] Furthermore, as a preferred embodiment, the inner wall of the sealing ring is rifling.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] In this invention, the permanent magnet direct drive motor is connected to the main shaft of the screw pump via a connecting shaft, while the rotor adopts a segmented structure. On the one hand, the segmented rotor, combined with the elastic deformation of the support spring and torsion spring, can effectively absorb and mitigate the increased torque and axial impact energy, avoid the huge mechanical stress caused by rigid connection, and protect the motor, connecting shaft and pump body itself. On the other hand, it can better adapt to the possible load fluctuations, medium changes or slight jamming conditions of the screw pump, temporarily store or release energy through elastic deformation, prevent overload damage, and enhance the stability of the system.

[0028] In addition, the water-cooling ring in this invention can effectively cool the casing of the permanent magnet direct drive motor by liquid cooling. The annular space formed between the water-cooling ring and the oil sealing ring can also store the cooling medium, thereby achieving liquid cooling of the coil windings on the stator. A collar is slidably installed inside the water-cooling ring. As the output torque of the screw pump increases under high load, the through hole on the collar gradually connects with the radial hole on the water-cooling ring. The cooling medium in the water-cooling ring can enter the annular space to achieve internal circulation cooling, thereby effectively cooling the coil windings and ensuring the reliability and lifespan of the motor under heavy load and continuous operation. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the disassembled structure of the permanent magnet direct drive motor in this invention;

[0031] Figure 3 This is a cross-sectional view of the internal structure of the permanent magnet direct drive motor in this invention. Figure 1 ;

[0032] Figure 4 This is a cross-sectional view of the internal structure of the permanent magnet direct drive motor in this invention. Figure 2 ;

[0033] Figure 5 This is a schematic diagram of the water-cooling ring in this invention;

[0034] Figure 6 This is a schematic diagram of the cross-sectional structure of the stator in this invention;

[0035] Figure 7 This is a cross-sectional view of the collar structure in this invention;

[0036] Figure 8 This is a schematic diagram of the rotor structure in this invention;

[0037] In the diagram: 1. Housing; 11. End cover; 12. Dustproof heat dissipation cover; 13. Connecting shaft; 14. Screw pump; 15. Stator; 16. Bearing; 17. Tail cover; 2. Water cooling ring; 21. Annular groove; 22. Axial flow channel; 23. Liquid inlet hole; 24. Liquid outlet hole; 25. Radial flow hole; 26. Thrust plate; 3. Rotor; 31. Rotating shaft; 32. Sliding shaft; 33. Fixed bushing; 34. Arc-shaped flange; 4. Oil sealing ring; 41. Front sealing plate; 42. Rear sealing plate; 43. Ventilation hole; 44. Liquid guide plate; 45. Drain hole; 46. Inner channel; 5. Collar; 51. Flow stop insert; 52. Through hole. Detailed Implementation

[0038] Please see Figures 1-8 In this embodiment of the invention, a high-stability permanent magnet direct-drive motor for a screw pump includes:

[0039] The housing 1 has an end cap 11 that is detachably fixed to one end;

[0040] The water-cooling ring 2 is coaxially fixed inside the housing 1;

[0041] The stator 15 is installed inside the housing 1 and coaxially fixed in the water-cooling ring 2. The stator 15 is provided with coil windings. The water-cooling ring 2 can conduct heat to the stator 15 and the housing 1 to reduce the temperature, thereby reducing the operating temperature.

[0042] The rotor 3 is rotatably installed inside the housing 1. Bearings 16 are installed on the other end of the housing 1 and on the end cover 11. The two ends of the rotor 3 are respectively fixed to the inner ring of the bearing 16.

[0043] The connecting shaft 13 is rotatably connected to one end of the screw pump 14 and connected to the main shaft of the screw pump 14. The other end of the connecting shaft 13 is connected to the rotor 3, thus realizing the direct connection between the rotor 3 and the main shaft of the screw pump 14.

[0044] In this embodiment, an oil sealing ring 4 is fixed inside the housing 1 between the rotor 3 and the stator 15. A front sealing plate 41 is fixed at one end of the water cooling ring 2 near the end cover 11, and a rear sealing plate 42 is fixed at the other end of the water cooling ring 2. The front sealing plate 41 and the rear sealing plate 42 are respectively sealed and assembled with the two ends of the oil sealing ring 4. In this way, on the one hand, the annular space formed between the oil sealing ring 4 and the water cooling ring 2 stores the cooling medium, realizing direct cooling of the coil winding with high cooling efficiency and significant temperature reduction effect. On the other hand, it can form an air cooling channel for the rotor 3. By rotating the rotor 3, a forced convection airflow is generated in the air cooling channel to achieve air cooling of the rotor 3 and prevent its high-temperature demagnetization.

[0045] Both the front sealing plate 41 and the rear sealing plate 42 are provided with multiple ventilation holes 43. In this way, when the rotor 3 is rotating, the external airflow can enter the oil sealing ring 4 through the ventilation holes 43 of the front sealing plate 41, carry away the heat on the surface of the rotor 3 and discharge it from the ventilation holes 43 of the rear sealing plate 42. The end of the housing 1 near the rear sealing plate 42 is equipped with a tail cover 17, and a dustproof heat dissipation cover 12 is installed on the outside of the tail cover 17 for ventilation and dust prevention.

[0046] In a preferred embodiment, two annular grooves 21 are symmetrically formed at both ends of the sidewall of the water-cooling ring 2. A plurality of axially arranged axial flow channels 22 are distributed circumferentially between the two annular grooves 21. The sidewall of the housing 1 is provided with a liquid inlet hole 23 and a liquid outlet hole 24. The liquid inlet hole 23 and the liquid outlet hole 24 are respectively connected to the two annular grooves 21. That is to say, the cooling medium enters the housing through the liquid inlet hole 23 and flows along the annular grooves 21 of the water-cooling ring 2. Then it flows through each axial flow channel 22 to the other annular groove 21 and finally exits through the liquid outlet hole 24, realizing the circulation of coolant and effectively cooling the housing quickly.

[0047] In this embodiment, the gaps between each of the axial flow channels 22 and the coil windings are connected accordingly, and multiple flow holes 25 are equidistantly distributed on the side wall of the water-cooling ring 2 and within the axial flow channels 22.

[0048] Furthermore, a collar 5 is coaxially slidably installed on the inner wall of the water-cooling ring 2. The side wall of the collar 5 is provided with through holes 52 corresponding to each of the radial flow holes 25. When the through holes 52 on the collar 5 are connected to the radial flow holes 25, the cooling medium in each axial flow channel 22 can flow radially into the annular space formed between the sealing oil ring 4 and the water-cooling ring 2 through the radial flow holes 25, effectively cooling the coil winding quickly and preventing the coil winding from overheating.

[0049] A thrust plate 26 is axially slidably installed inside the housing 1 near the end cover 11. The thrust plate 26 is coaxially fixed with the collar 5. The thrust plate 26 pushes the collar 5 closer to or away from the end cover 11 during axial sliding.

[0050] In this embodiment, a flow-stopping insert 51 is embedded in the side wall of the water-cooling ring 2 at the drain end of each axial flow channel 22. Each flow-stopping insert 51 is radially sealed and slidably assembled on the water-cooling ring 2. The lower end of each flow-stopping insert 51 is provided with a wedge-shaped inclined surface.

[0051] The outer wall of the end of the collar 5 is provided with a chamfer. The collar 5 is in contact with the flow-stopping insert 51 by the chamfer. With this configuration, when the through hole 52 on the collar 5 is fully aligned with the radial flow hole 25, the collar 5 can use the chamfer at the end to radially lift each flow-stopping insert 51. The flow-stopping insert 51 blocks the axial flow of the cooling medium in the axial flow channel 22, so that the cooling medium is fully immersed in the annular space, ensuring targeted cooling and temperature reduction of the coil winding.

[0052] In this embodiment, a liquid guide plate 44 is slidably and sealed on the same side of the rear sealing plate 42 inside the housing 1. The rear sealing plate 42 has multiple drainage holes 45, each of which is connected to the liquid guide plate 44. An inner channel 46 is provided on the tail cover 17. One end of the inner channel 46 is connected to the liquid guide plate 44. The liquid guide plate 44 has an annular or cross-shaped flow channel. The cooling medium enters the flow channel through the micropores on the surface of the liquid guide plate 44 and finally flows into the inner channel 46 through the side hole on the outer circumferential side wall of the liquid guide plate 44 and is discharged. The other end of the inner channel 46 is connected to the drain hole 24.

[0053] In a preferred embodiment, the rotor 3 includes:

[0054] A rotating shaft 31 has a rotor core mounted on its outside, and multiple permanent magnets are distributed circumferentially on the rotor core.

[0055] A sliding shaft 32 is slidably connected to one end of the rotating shaft 31 near the end cover 11, and the thrust disk 26 is mounted on the sliding shaft 32 via a bearing;

[0056] A fixed bushing 33 is fixed at one end to a connecting shaft 13. One end of a sliding shaft 32 extends into and is connected to the fixed bushing 33. The outer peripheral wall of the sliding shaft 32 has two centrally symmetrical oblique notches. The fixed bushing 33 has an arc-shaped flange 34 corresponding to the oblique notches. Each arc-shaped flange 34 slides in contact with the oblique notches. In this way, when the rotor 3 rotates, the arc-shaped flange 34 can contact and engage with the oblique notches. The rotating shaft 31, the sliding shaft 32, and the fixed bushing 33 rotate synchronously, thereby driving the main shaft of the screw pump to rotate through the connecting shaft 13.

[0057] In this embodiment, the sliding shaft 32 and the fixed bushing 33 are rotatably assembled, and there is a rotation gap between them. A torsion spring is provided between the sliding shaft 32 and the fixed bushing 33. That is, under no external force, the torsion spring maintains the maximum rotation gap between the sliding shaft 32 and the fixed bushing 33 through the elastic force. At this time, the arc-shaped flange 34 and the oblique notch are partially separated, and the sliding shaft 32 is located on the side close to the end cover 11. When the screw pump is rotating at low torque, the sliding shaft 32 on the rotating shaft 31 and the fixed bushing 33 are relatively deflected, and the torsion spring is partially compressed. At this time, the sliding shaft 32 can slide away from the end cover 11 under the sliding contact of the arc-shaped flange 34 and the oblique notch. Meanwhile, the thrust plate 26 outside the sliding shaft 32 can synchronously slide the through hole 52 and the flow hole 25 to gradually connect.

[0058] As the screw pump operates at high power and high torque, the motor operating current increases, the coil winding heats up intensely, the torsion spring is completely compressed, the sliding shaft 32 is located near the oil sealing ring 4, and the through hole 52 is fully connected to the radial flow hole 25, achieving targeted and efficient cooling of the coil winding.

[0059] In this embodiment, a support spring is connected between the sliding shaft 32 and the rotating shaft 31. The sliding shaft 32 slides away from the rotating shaft 31 by the elastic force of the support spring. With this configuration, when the screw pump is initially started, the sliding shaft 32 approaches the oil sealing ring 4 in the sliding contact between the arc-shaped flange 34 and the oblique notch. Both the support spring and the torsion spring are compressed. Therefore, the segmented rotor structure, combined with the elastic deformation of the support spring and the torsion spring, effectively absorbs and mitigates the torque and axial impact energy caused by the increased friction, avoids the huge mechanical stress caused by the rigid connection, and protects the motor, the connecting shaft and the pump body itself.

[0060] In this embodiment, the inner wall of the sealing ring 4 is rifling, which forces the flowing air to generate a strong rotational motion. The swirling flow generates a centrifugal effect, throwing the airflow towards the wall of the sealing ring 4 and significantly extending the actual flow path of the air in the channel. This greatly enhances the shearing and mixing effect between the airflow and the rotor core and permanent magnet surface, thereby significantly improving the convective heat transfer coefficient and removing more heat.

[0061] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-stability permanent magnet direct-drive motor for screw pumps, characterized in that, It includes: The housing (1) has an end cap (11) that is detachably fixed at one end. The water-cooling ring (2) is coaxially fixed inside the housing (1); The stator (15) is installed inside the housing (1) and coaxially fixed in the water-cooling ring (2). The stator (15) is provided with coil windings. The rotor (3) is rotatably installed inside the housing (1). The other end of the housing (1) and the end cover (11) are both equipped with bearings (16). The two ends of the rotor (3) are respectively fixed to the inner ring of the bearing (16). A connecting shaft (13) is rotatably connected to one end of a screw pump (14) and connected to the main shaft of the screw pump (14). The other end of the connecting shaft (13) is connected to a rotor (3). The water-cooling ring (2) has two annular grooves (21) symmetrically opened at both ends of its sidewall. A plurality of axially arranged axial flow channels (22) are distributed circumferentially between the two annular grooves (21). The sidewall of the housing (1) is provided with a liquid inlet hole (23) and a liquid outlet hole (24). The liquid inlet hole (23) and the liquid outlet hole (24) are respectively connected to the two annular grooves (21). Each of the axial flow channels (22) is connected to the gap between the coil winding and the water cooling ring (2). Multiple radial flow holes (25) are equidistantly distributed on the side wall of the water cooling ring (2) and within the axial flow channel (22). Furthermore, a collar (5) is coaxially and slidably installed on the inner wall of the water-cooling ring (2), and the side wall of the collar (5) is provided with through holes (52) corresponding to each of the flow holes (25). A thrust plate (26) is axially slidably installed inside the housing (1) near the end cover (11), and the thrust plate (26) is coaxially fixed with the collar (5); The sidewall of the water-cooling ring (2) is provided with a flow-stopping insert (51) embedded at the drain end of each axial flow channel (22). Each flow-stopping insert (51) is radially sealed and slidably assembled on the water-cooling ring (2). The lower end of each flow-stopping insert (51) is provided with a wedge-shaped inclined surface. The outer wall of the end of the collar (5) is provided with a chamfer, and the collar (5) is in contact with the flow stop insert (51) by the chamfer; The rotor (3) includes: A rotating shaft (31) has a rotor core mounted on its outside, and multiple permanent magnets are distributed around the circumference of the rotor core. A sliding shaft (32) is slidably connected to one end of the rotating shaft (31) near the end cover (11), and the thrust disk (26) is mounted on the sliding shaft (32) via a bearing; A fixed bushing (33) is fixed at one end to a connecting shaft (13). One end of the sliding shaft (32) extends into the fixed bushing (33). The outer peripheral wall of the sliding shaft (32) is provided with two oblique notches that are centrally symmetrical. The fixed bushing (33) is provided with an arc-shaped flange (34) corresponding to the oblique notch. Each arc-shaped flange (34) slides in contact with the oblique notch.

2. The high-stability permanent magnet direct-drive motor for a screw pump according to claim 1, characterized in that: An oil sealing ring (4) is fixed inside the housing (1) between the rotor (3) and the stator (15). A front sealing plate (41) is fixed at one end of the water cooling ring (2) near the end cover (11), and a rear sealing plate (42) is fixed at the other end of the water cooling ring (2). The front sealing plate (41) and the rear sealing plate (42) are respectively sealed and assembled with the two ends of the oil sealing ring (4). The front sealing plate (41) and the rear sealing plate (42) are provided with multiple ventilation holes (43). The end of the housing (1) near the rear sealing plate (42) is equipped with a tail cover (17), and a dustproof heat dissipation cover (12) is installed on the outside of the tail cover (17).

3. The high-stability permanent magnet direct-drive motor for a screw pump according to claim 2, characterized in that: Inside the housing (1), a liquid guide plate (44) is slidably connected to the same side of the rear sealing plate (42) in a sealed manner. The rear sealing plate (42) has multiple drainage holes (45), each of which is connected to the liquid guide plate (44). The tail cover (17) has an inner channel (46), one end of which is connected to the liquid guide plate (44), and the other end of which is connected to the drain hole (24).

4. The high-stability permanent magnet direct-drive motor for a screw pump according to claim 1, characterized in that: The sliding shaft (32) is rotatably assembled with the fixed bushing (33), and there is a rotation gap between them. A torsion spring is provided between the sliding shaft (32) and the fixed bushing (33).

5. The high-stability screw pump permanent magnet direct drive motor according to claim 1, characterized in that: A support spring is connected between the sliding shaft (32) and the rotating shaft (31), and the sliding shaft (32) slides away from the rotating shaft (31) by the elastic force of the support spring.

6. The high-stability screw pump permanent magnet direct drive motor according to claim 2, characterized in that: The inner wall of the sealing ring (4) is rifling.

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