CN111306070B

CN111306070B - Centrifugal pump with rotor integrated blade axial flux permanent magnet motor

Info

Publication number: CN111306070B
Application number: CN202010101280.0A
Authority: CN
Inventors: 黄允凯; 祝子冲; 夏雪; 彭飞
Original assignee: Southeast University; Liyang Research Institute of Southeast University
Current assignee: Southeast University; Liyang Research Institute of Southeast University
Priority date: 2020-02-19
Filing date: 2020-02-19
Publication date: 2021-02-19
Anticipated expiration: 2040-02-19
Also published as: CN111306070A

Abstract

The invention discloses a centrifugal pump with an axial flux permanent magnet motor with rotor integrated blades, which comprises a casing and the axial flux permanent magnet synchronous motor arranged in the casing. The casing comprises a stator casing and a rotor casing, and the axial flux permanent magnet motor comprises a stator and a rotor. The stator comprises a stator core and a coil, the rotor comprises a rotor yoke, a lining and a permanent magnet, and the rotor simultaneously forms an impeller of the centrifugal pump. The permanent magnet is embedded in the bushing in an interference fit manner and serves as a single blade of the centrifugal pump impeller. When the impeller works, the stator winding is electrified to generate a rotating magnetic field, and the rotating magnetic field interacts with the permanent magnetic field on the impeller to drive the impeller to rotate. In this process, the fluid medium flows through the flow passages between the blades and the pressure increases. The centrifugal pump has the advantages of small axial size, small number of parts, high power density and the like. Meanwhile, the fluid medium is used for cooling heat generating components of the motor, and the centrifugal pump can be used in extreme environments. The problem of wind noise generated by the thin-wall blade of the traditional centrifugal pump is also solved.

Description

Centrifugal pump with rotor integrated blade axial flux permanent magnet motor

Technical Field

The invention relates to a centrifugal pump, in particular to a centrifugal pump with a rotor integrated blade axial flux permanent magnet motor, and belongs to the technical field of motors and fluid machinery.

Background

With the continuous acceleration of the electrification process of the vehicles, the adoption of electric drive for the vehicle-mounted subsystem gradually becomes the mainstream. Wherein, the pump and fan system driven by the motor has a larger proportion. In order to increase the endurance mileage, the electric vehicle requires each subsystem to have a higher power density and to stably operate when the ambient temperature changes greatly. Meanwhile, the overall reliability index of the vehicle is higher, and the reduction of the number of parts of each subsystem is an important direction for improving the reliability and reducing the assembly workload and the labor cost.

Secondly, electric vehicles require a certain torque overload capacity of the drive motor of the individual subsystems, in particular in pumps which deliver fluid media of high viscosity. Considering that the installation environment of the pump and fan subsystem is worse, the heat dissipation design of the driving motor is particularly difficult. In addition, in order to improve the comfort of passengers, the requirements for noise in the vehicle-mounted environment, particularly in the vehicle, are more strict. It has been found that noise between the thin walled blades in the pump and fan impellers and the fluid medium is a significant source of vehicle noise. This partial noise suppression can significantly reduce the noise level of the vehicle.

The existing pump and fan subsystems are generally in a discrete structure, and a motor rotor and an impeller are required to be coaxially fixed or the impeller is required to be fixed on the motor rotor. These two fixing systems are bulky, in particular with large axial dimensions, and are inconvenient to install in an electric vehicle. The larger volume reduces the power density and efficiency of the pump and fan system. Meanwhile, the system has more parts, high sealing difficulty and low reliability. On the other hand, the torque pulsation of the driving motor in the conventional pump and fan is large, so that the problems of vibration and noise caused by the large torque pulsation are difficult to solve. When the vibration of the motor is transmitted to the impeller, the wind noise generated from the impeller is further increased.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the centrifugal pump with the rotor integrated blade axial flux permanent magnet motor is characterized in that an impeller of the centrifugal pump and a rotor of the axial flux permanent magnet motor are integrally designed, and the defects in the prior art are overcome.

The invention adopts the following technical scheme for solving the technical problems:

a centrifugal pump containing a rotor integrated blade axial flux permanent magnet motor comprises a machine shell and the axial flux permanent magnet motor arranged in the machine shell, wherein the machine shell comprises a rotor machine shell and a stator machine shell which are sealed through bolts and/or adhesives, the rotor machine shell is gradually opened along the flowing direction of a fluid medium, an outlet of the fluid medium is reserved on the rotor machine shell, and an inlet of the fluid medium is reserved on the stator machine shell;

the axial flux permanent magnet motor comprises a rotor and a stator, wherein the rotor comprises a rotor yoke, a bushing and a permanent magnet, the rotor yoke is of a disc-shaped structure, the bushing is of a fan-shaped thin-wall structure, and the bushing is uniformly distributed on one surface of the rotor yoke along the circumferential direction; the permanent magnet is a cylinder with a sector section, the pole arc angle of the permanent magnet is smaller than the pole pitch of the magnetic pole of the rotor of the axial flux permanent magnet motor, two edges of the permanent magnet along the radius direction are both arc-shaped, the inner and outer sections of the arc of the permanent magnet are staggered along the circumferential direction, the permanent magnet is magnetized along the direction of the rotating shaft, and the polarity of the permanent magnet changes along the circumferential direction alternately; the inner shape of the bush is the same as the shape of the permanent magnet, the permanent magnet and the bush form a single blade of the centrifugal pump after being assembled, the blades are uniformly distributed on one surface of the rotor yoke along the circumferential direction, and the blades and the rotor yoke form an impeller, namely a rotor, of the centrifugal pump;

the stator comprises a stator core and a coil, a groove for placing the coil is processed on the stator core, the groove faces the impeller in the axial direction, the coil is embedded into the groove, an insulating material is arranged between the coil and the groove, the coil and the stator core are encapsulated into a torus stator by adopting epoxy resin, and the torus stator is pressed into the torus-shaped groove of the stator casing;

a space which is communicated along the radius direction exists between two adjacent blades, and two opposite side surfaces between the two adjacent blades, a surface of a rotor yoke facing the space and a surface of a filled torus stator facing the space form a single flow channel of a fluid medium;

the impeller is connected with the rotor shell through a radial bearing, a gap exists between the impeller and the rotor shell, the impeller and the stator shell are fixed through an axial thrust bearing, the impeller and the stator are concentric, and the stator and the impeller axially have a gap.

As a preferable aspect of the present invention, the outer edge of the rotor case is shaped by an archimedean spiral.

As a preferable scheme of the present invention, the bushing and the rotor yoke are integrally formed, or the bushing and the rotor yoke are connected by welding, or a groove having the same shape as the bushing is formed on one surface of the rotor yoke, and the bushing is inserted into the groove by interference fit.

As a preferable scheme of the present invention, the permanent magnet and the bushing are assembled by interference fit, or by adhesive fixation, or by snap fixation, or by bolt fixation.

As a preferred scheme of the present invention, the axial flux permanent magnet motor adopts a dual-rotor single-stator structure, the stator adopts a non-magnetic yoke structure, the stator includes a plurality of stator cores and coils wound around each stator core, and the dual rotors are arranged on both sides of the stator along the axial direction.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

1. the invention designs the impeller of the centrifugal pump and the rotor of the axial flux permanent magnet motor integrally without an additional impeller and a connecting device with a motor rotating shaft. The number of system components and the axial size are greatly reduced, the structure is compact, and the reliability is improved. Meanwhile, the weight of the system is reduced, the power density is increased, and the overall efficiency is obviously improved. The existence of the permanent magnet improves the efficiency and the output torque of the motor, and has obvious advantages when a fluid medium with higher viscosity is pumped.

2. In the invention, fluid flows through the stator and the rotor of the axial flux permanent magnet motor, so that loss in the motor is easily conducted out in time, and the temperature rise of the rotor and a winding is favorably reduced. Lower grade permanent magnets and/or less expensive winding materials can be used with the same magnetic performance and losses.

3. The bushing and the permanent magnet are in interference fit, so that the rigidity of the centrifugal pump blade is greatly improved, and wind noise generated by the action of the thin-wall blade and fluid is reduced.

4. The permanent magnet of the invention greatly reduces the torque pulsation, and is beneficial to reducing the vibration and noise of the motor.

Drawings

Fig. 1 is an overall structural view of a centrifugal pump including a rotor integrated blade axial flux permanent magnet motor according to the present invention.

FIG. 2 is a schematic view of a stator housing of the centrifugal pump of the present invention.

FIG. 3 is a schematic view of a rotor housing of the centrifugal pump of the present invention.

Fig. 4 is a schematic diagram of an axial flux permanent magnet machine of the present invention.

Fig. 5 is a schematic view of an axial flux permanent magnet machine rotor of the present invention.

Fig. 6 is a schematic view of permanent magnets on an axial flux permanent magnet machine rotor of the present invention.

Fig. 7 is a schematic view of an axial flux permanent magnet machine stator of the present invention.

Fig. 8 is a schematic diagram of the axial flux permanent magnet motor stator of the present invention after potting.

FIG. 9 is a schematic view of the flow channels and impeller of the centrifugal pump of the present invention.

Detailed Description

The technical solution of the present invention is further explained by specific embodiments with reference to fig. 1 to 9. It should be noted that in order to avoid obscuring the core features of the present invention from the description of the fine features (e.g., the fixing holes in the housing and the motor winding terminals), only the structure and implementation steps associated with the main features of the present invention are shown in fig. 1-9. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1, a centrifugal pump comprising a rotor-integrated-blade axial flux motor is composed of a housing 5 and a 10-pole 12-slot axial flux permanent magnet motor 6 installed therein.

As shown in fig. 1, 2, 3 and 9, the housing 5 is formed by combining a rotor housing 51 and a stator housing 52, which are sealed by bolts and an adhesive. The rotor housing 51 and the stator housing 52 are formed by molding engineering plastics to form a closed structure. The rotor case 51 is formed in an involute shape in the fluid flow direction. The stator housing 52 has an inlet 11 for the fluid medium and the rotor housing 51 has an outlet 12 for the fluid medium. The shape of the outer edge 57 of the rotor housing 51 and the flow passage 55 is determined by the archimedean spiral.

As shown in fig. 4 and 5, the axial flux permanent magnet motor 6 includes two parts, namely a rotor 2 and a stator 3. The rotor 2 is composed of a rotor yoke 23, a bushing 22, and a permanent magnet 21. The rotor yoke 23 has a disk-like structure and a thickness of 6 mm. The bush 22 is a fan-shaped thin-walled structure, and a portion near the rotation center is modified into a circular arc 25 to reduce local pressure loss. The 10 bushings 22 are uniformly distributed on the rotor yoke 23, and the rotor yoke 23 and the bushings 22 are integrally processed by magnetic conductive 45# steel. The bushing 22 and the rotor yoke 23 may be separately machined and connected by welding. Or a groove having the same shape as the bushing 22 is formed in the rotor yoke 23, and the bushing 22 is fixed by being fitted into the rotor yoke 23 by interference.

As shown in fig. 6, the permanent magnet 21 is a cylindrical body having a sector-shaped cross section, and has a pole arc angle of 22.5 ° smaller than the pole pitch of the magnetic poles of 36 ° in the present embodiment. The

sides

28 and 29 of the permanent magnet 21 in the radial direction are arc-shaped, and the shapes of the

sides

28 and 29 are determined according to the fluid flow rate and the pressure. The inner and

outer arcs

26 and 27 of the permanent magnet 21 are staggered by 3.6 degrees along the circumferential direction, so that the permanent magnet 21 generates a slant pole effect along the circumferential direction. The permanent magnets 21 are made of sintered ferrite materials, are magnetized along the direction of the rotating shaft, and the polarity of the 10 permanent magnets 21 is changed along the circumferential direction. The permanent magnet 21 and the bushing 22 may also be fixed in other ways, such as gluing, snapping, bolting, etc.

As shown in fig. 5 and 9, the inner shape of the bushing 22 is the same as the outer shape of the permanent magnet 21, and the bushing 22 and the permanent magnet 21 are assembled by interference fit. The assembled permanent magnets 21 and bushings 22 constitute a single vane 70 of the centrifugal pump. The 10 blades 70 are uniformly distributed on the rotor yoke 23 in the circumferential direction, and together with the rotor yoke 23, constitute an impeller of the centrifugal pump (i.e., the rotor 2 of the axial flux permanent magnet synchronous motor). In order to reduce the possibility of corrosion of the permanent magnet, the permanent magnet can be sealed by a non-magnetic conductive sheet with the same shape and size as the lining, and the non-magnetic conductive sheet and the lining are fixed by welding.

As shown in fig. 2, 7 and 8, the stator 3 includes a stator core 31 formed by winding a 0.5mm electrical steel sheet and a coil 33 made of an enameled wire. The stator core 31 is formed by wire electrical discharge machining 12 slots 32 for housing the motor winding coils 33, the slots 32 being axially opposed to the impeller. The three-phase motor has 12 coils wound in sequence and embedded in the slot 32, and an insulating material (not shown) is arranged between the coil 33 and the slot 32. To reduce fluid flow resistance, the coil 33 and stator core 31 are potted as a full torus stator 42 using epoxy 41 and press fit into a torus shaped slot 56 in the stator case 52. The diameter of the ring stator 42 is the same as the diameter of the impeller, which is 90mm in this embodiment. The torus stator 42 after potting may also be of a different diameter than the impeller.

As shown in fig. 5, the blades 70 are spaced apart from each other in the radial direction. The sides of two adjacent blades 70, the faces of the rotor yoke 23 facing the gap and the faces of the torus stator 42 facing the gap together form a single flow channel 24 for the fluid medium. The sectional area of the flow passage gradually increases along the radial direction. Vanes may be machined between the blades 70 of the impeller to optimize fluid flow and reduce pressure losses.

As shown in fig. 2, 3, 7 and 9, the impeller is connected to the rotor housing 51 through a radial bearing 53 with a gap of 0.35mm from the rotor housing 51. Meanwhile, in order to counteract the axial magnetic pull force, the impeller and the stator housing 52 are fixed by an axial thrust bearing 54. The radial bearing 53 and the axial thrust bearing 54 realize the support and positioning of the impeller in the axial direction and the radial direction, and ensure the concentricity of the impeller and the motor stator 3. The axial clearance between the stator 3 and the impeller is 0.5mm, and the smaller the clearance value is, the better the assembly and operation safety is guaranteed.

As shown in fig. 4 and 9, in normal operation, three-phase sinusoidal currents are applied to the three-phase windings of the axial flux permanent magnet motor 6, and a rotating armature magnetic field is generated in the air gap 8 between the stator 3 and the rotor 2. The armature magnetic field rotation direction coincides with the involute direction of the flow path 55, and is clockwise in fig. 9. The armature magnetic field interacts with the permanent magnetic field generated by the permanent magnet 21 to drive the impeller to rotate, and the blades 70 on the impeller drive the fluid to flow along the radial direction under the action of centrifugal force, and the fluid flows out of the outlet 12 of the centrifugal pump through the gap and the flow channel 55. The pressure of the fluid is increased during this process, and the pressurizing function of the pump is realized. For ease of manufacturing, the shape of the rotor housing 51 and the flow passages 55 may be determined by an equilateral element method.

In order to reduce the axial unbalanced force, the axial flux permanent magnet motor 6 can adopt a double-rotor single-stator structure. The motor stator adopts a non-magnetic yoke structure and is composed of a plurality of iron core units and coils 33 wound on the iron core units. The double rotors are arranged on two sides of the stator along the axial direction, and the structure of the rotors is the same as that of the rotors.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.

Claims

1. A centrifugal pump comprising a rotor integrated blade axial flux permanent magnet motor, comprising a casing (5) and an axial flux permanent magnet motor (6) incorporated therein, characterized in that the casing (5) comprises a rotor casing (51) and a stator casing (52) which are sealed by bolts and/or an adhesive, the rotor casing (51) is tapered in a flow direction of a fluid medium, an outlet (12) for the fluid medium is left in the rotor casing (51), and an inlet (11) for the fluid medium is left in the stator casing (52);

the axial flux permanent magnet motor (6) comprises a rotor (2) and a stator (3), wherein the rotor (2) comprises a rotor yoke (23), a bushing (22) and a permanent magnet (21), the rotor yoke (23) is of a disc-shaped structure, the bushing (22) is of a fan-shaped thin-wall structure, and the bushing (22) is uniformly distributed on one surface of the rotor yoke (23) along the circumferential direction; the permanent magnet (21) is a cylinder with a sector section, the pole arc angle of the permanent magnet is smaller than the pole pitch of the rotor magnetic pole of the axial flux permanent magnet motor (6), two edges of the permanent magnet (21) along the radius direction are both arc-shaped, the inner and outer arcs of the permanent magnet (21) are staggered along the circumferential direction, the permanent magnet (21) is magnetized along the rotating shaft direction, and the polarity changes along the circumferential direction alternately; the inner shape of the bushing (22) is the same as the outer shape of the permanent magnet (21), the permanent magnet (21) and the bushing (22) form a single blade (70) of the centrifugal pump after being assembled, the blades (70) are uniformly distributed on one surface of a rotor yoke (23) along the circumferential direction, and form an impeller, namely a rotor (2), of the centrifugal pump together with the rotor yoke (23);

the stator (3) comprises a stator core (31) and a coil (33), a groove (32) for placing the coil (33) is processed on the stator core (31), the groove (32) faces the impeller in the axial direction, the coil (33) is embedded into the groove (32), an insulating material is arranged between the coil (33) and the groove (32), the coil (33) and the stator core (31) are encapsulated into a torus stator (42) by adopting epoxy resin, and the torus stator (42) is pressed into a torus-shaped groove (56) of the stator casing (52);

a space penetrating along the radius direction exists between two adjacent blades (70), and two opposite side surfaces between the two adjacent blades (70), a surface of a rotor yoke (23) facing the space and a surface of a filled torus stator (42) facing the space form a single flow channel (24) of a fluid medium;

the impeller is connected with the rotor shell (51) through a radial bearing (53), a gap exists between the impeller and the rotor shell (51), the impeller and the stator shell (52) are fixed through an axial thrust bearing (54), the impeller and the stator (3) are concentric, and the stator (3) and the impeller axially have a gap.

2. Centrifugal pump with rotor integrated blade axial flux permanent magnet machine according to claim 1, characterized by the fact that the shape of the outer rim (57) of the rotor casing (51) is determined by an archimedean spiral.

3. The centrifugal pump with the rotor integrated blade axial flux permanent magnet motor according to claim 1, wherein the bushing (22) is integrally formed with the rotor yoke (23), or the bushing (22) and the rotor yoke (23) are connected by welding, or a groove with the same shape as the bushing (22) is formed on one surface of the rotor yoke (23), and the bushing (22) is embedded in the groove by interference fit.

4. Centrifugal pump with rotor integrated blade axial flux permanent magnet machine according to claim 1, characterized in that the permanent magnets (21) are assembled with the bushing (22) by interference fit, or by adhesive fixation, or by snap fixation, or by bolt fixation.

5. The centrifugal pump comprising a rotor-integrated-blade axial-flux permanent magnet motor according to claim 1, wherein the axial-flux permanent magnet motor (6) has a double-rotor single-stator structure, the stator has a yoke-free structure, the stator includes a plurality of stator cores and coils wound around each of the stator cores, and the double rotors are axially disposed on both sides of the stator.