A magnetic levitation high-speed induction motor without a thrust disk

Abstract

The present invention relates to the field of magnetic levitation motors, and particularly to a magnetic levitation high-speed asynchronous motor without a thrust disk. The motor includes a motor housing, a stator, a motor shaft, a radial bearing, and an axial bearing; the motor shaft includes a first shaft section, two second shaft sections respectively located outside both ends of the first shaft section, and two third shaft sections respectively located outside both ends of the second shaft sections; a first shaft shoulder is formed on the outer end surface of the first shaft section at the connection position between the second shaft section and the first shaft section; a second shaft shoulder is formed on the outer end surface of the second shaft section at the connection position between the third shaft section and the second shaft section; both the first shaft shoulder and the second shaft shoulder are magnetic conductive surfaces, and the first shaft shoulder and the second shaft shoulder are respectively connected to the stator magnetic circuit support ends of the axial bearing. The motor provides acting forces through the stator magnetic circuits of the axial bearing to the magnetic conductive surfaces provided on the outer end surfaces of the first shaft section and the second shaft section respectively without arranging a thrust disk, cancels the assembly step of the thrust disk, saves the internal space of the motor, and reduces the cost of the whole motor.

Description

Technical Field

[0001] The present invention relates to the field of magnetic levitation motors, and particularly to a magnetic levitation high-speed asynchronous motor without a thrust disk. Background Art

[0002] With the development of science and technology and the needs of production, magnetic levitation high-speed motors have become one of the research hotspots in the international electrical engineering field. Due to the advantages of high energy density, small structural size, high efficiency, etc. of magnetic levitation high-speed motors, they have currently been widely used in industrial fields such as micro gas turbines, high-speed centrifugal compressors, molecular pumps, high-speed machining centers, flywheel energy storage, etc., and their application scope is still expanding continuously. During the operation of a magnetic levitation motor, the stability of the motor rotor is the key to ensuring the smooth and efficient operation of the motor. The magnetic properties of the permanent magnets of the motor rotor and the dynamic balance of the rotor itself directly affect the working performance of the magnetic levitation motor.

[0003] Chinese Patent Application for Invention (Publication No. CN206035859U, Publication Date: Mar. 22, 2017) discloses a magnetic levitation bearing high-speed asynchronous motor direct drive centrifugal compressor, including a housing, an air inlet and an air outlet are provided on the housing, a compressor impeller is installed in the housing, the housing is fixedly connected to a motor connection flange, and further includes a magnetic levitation bearing high-speed asynchronous motor. The magnetic levitation bearing high-speed asynchronous motor includes a motor housing, a motor stator installed in the motor housing, a motor rotor shaft cooperating with the motor stator, and a magnetic levitation radial bearing cooperating with the motor rotor shaft. The motor housing is fixedly connected to the motor connection flange, the motor rotor shaft is fixedly connected to the compressor impeller, the motor connection flange is fixedly connected to a diffuser, and an auxiliary rolling bearing for cooperating with the motor rotor shaft is fixed on the diffuser. It can achieve high speed and completely oil-free of the centrifugal compressor, and extend the service life of the magnetic levitation radial bearing.

[0004] The prior art has the following deficiencies: The motor shaft is connected to the thrust disk, and the stator magnetic circuit of the axial bearing restricts the axial position of the thrust disk to thereby restrict the axial position of the motor shaft; in this way, the shoulder of the motor shaft and the clearance ring shrink-fitted on the motor shaft are respectively used to limit both sides of the thrust disk to axially connect it to the motor shaft, which not only increases the assembly steps of the thrust disk but also increases the space required inside the motor; at the same time, the thrust disk and the motor shaft are not integral parts but two separate parts that need to be connected. When restricting the axial position of the motor shaft through the thrust disk, the strength of the thrust disk itself and the connection strength between the thrust disk and the motor shaft need to meet relatively high mechanical property requirements, which also increases the cost of the entire motor. Summary of the Invention

[0005] The object of the present invention is: to address the above problems, a magnetic levitation high-speed asynchronous motor without a thrust disk is proposed, which provides a magnetic force through the stator magnetic circuits of axial bearings to the outer end faces of the first shaft section and the second shaft section respectively without setting a thrust disk, cancels the assembly step of the thrust disk, saves the internal space of the motor, and reduces the cost of the entire motor.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A magnetic levitation high-speed asynchronous motor without a thrust disk, the motor includes a housing, a stator, a motor shaft, a radial bearing and an axial bearing; the motor shaft includes a first shaft section, two second shaft sections respectively located outside both ends of the first shaft section, and two third shaft sections respectively located outside both ends of the second shaft section; the cylindrical diameter of the second shaft section is smaller than that of the first shaft section, and a first shaft shoulder is formed on the outer end face of the first shaft section at the connection position between the second shaft section and the first shaft section; the cylindrical diameter of the third shaft section is smaller than that of the second shaft section, and a second shaft shoulder is formed on the outer end face of the second shaft section at the connection position between the third shaft section and the second shaft section; both the first shaft shoulder and the second shaft shoulder are magnetic conductive surfaces, and the first shaft shoulder and the second shaft shoulder are respectively connected to the stator magnetic circuit support ends of the axial bearing.

[0008] Preferably, the two second shaft sections and the two third shaft sections are both axially symmetrically distributed along the first shaft section.

[0009] Preferably, the second shaft section and the third shaft section are connected by a bevel transition.

[0010] Preferably, a permanent magnet is arranged inside the first shaft section, a copper-clad layer is arranged on the surface of the first shaft section, and the first shaft section is connected to the stator driving end; the second shaft section and the third shaft section are respectively connected to the axial bearing support end and the radial bearing support end.

[0011] Preferably, the copper-clad layer includes a concave part in the middle and convex parts on both sides, and the width of the concave part is the same as that of the stator driving end.

[0012] Preferably, a radial magnetic bearing rotor assembly is arranged on the outer surface of the third shaft section, and the radial magnetic bearing rotor assembly is connected to the magnetic circuit support end of the radial bearing.

[0013] Preferably, the motor shaft further includes a fourth shaft section, and the two fourth shaft sections are respectively located outside the two third shaft sections; the outer surface of the fourth shaft section is shrink-fitted with axially stacked and adhered laminations, and the laminations on the fourth shaft section are connected to the induction end of the axial sensor.

[0014] Preferably, the motor shaft further includes a fifth shaft section, and the two fifth shaft sections are respectively located outside the two fourth shaft sections, and the outer surface of the fifth shaft section is matched with the inner ring of the non-magnetic radial bearing.

[0015] Preferably, the outer surface of the fifth shaft section is provided with end face teeth, which are matched with the connection part of the impeller.

[0016] Preferably, screw holes are provided on the outer end face of the fifth shaft section, and the impeller is fixed on the screw holes and connected to the motor shaft.

[0017] The advantages of a magnetic levitation high-speed asynchronous motor adopting the above technical solution of the present invention are as follows:

[0018] The magnetic conduction surfaces of the first shaft shoulder and the second shaft shoulder are grouped in pairs and maintain the axial position under the drive of the stator magnetic circuit of the axial bearing; thus, the axial bearing can be made into a structure without a thrust disk, eliminating the need for assembling the thrust disk and saving the space of the motor. At the same time, the stator magnetic circuit of the axial bearing directly provides a force on the motor shaft, and the mechanical properties of the motor shaft itself are sufficient to meet the limit requirements; there is no need for extra high mechanical property requirements for the strength of the thrust disk and the connection strength between the thrust disk and the motor shaft when the thrust disk is acting, thereby reducing the cost of the entire equipment. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 2 It is a schematic structural diagram of the motor shaft.

[0021] Figure 3 It is a schematic structural diagram of the magnetic field circuit of the axial bearing.

[0022] Figure 4 It is a schematic structural diagram of the magnetic field circuit of the radial bearing.

[0023] Figure 5 It is a schematic structural diagram of the magnetic field of the stator and the copper-clad layer.

[0024] 11 - Front bearing housing, 12 - Rear bearing housing, 13 - Sensor, 14 - Protection bearing, 51 - Radial bearing stator, 52 - Radial bearing rotor. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following will describe in detail the specific embodiments of the present invention with reference to the drawings.

[0026] Embodiment 1

[0027] As Figures 1-5A magnetic levitation high-speed asynchronous motor without a thrust disk is shown. The motor includes a motor housing 1, a stator 2, a motor shaft 3, a radial bearing 5, and an axial bearing 6; the motor shaft 3 includes a first shaft section 31, two second shaft sections 32 respectively located outside both ends of the first shaft section 31, and two third shaft sections 33 respectively located outside both ends of the second shaft sections 32; the cylindrical diameter of the second shaft section 32 is smaller than that of the first shaft section 31, and a first shaft shoulder 37 is formed on the outer end face of the first shaft section 31 at the connection position between the second shaft section 32 and the first shaft section 31; the cylindrical diameter of the third shaft section 33 is smaller than that of the second shaft section 32, and a second shaft shoulder 38 is formed on the outer end face of the second shaft section 32 at the connection position between the third shaft section 33 and the second shaft section 32; both the first shaft shoulder 37 and the second shaft shoulder 38 are magnetic conductive surfaces, and the first shaft shoulder 37 and the second shaft shoulder 38 are respectively connected to the stator magnetic circuit support ends of the axial bearing 6. In this way, the magnetic conductive surfaces of the first shaft shoulder 37 and the second shaft shoulder 38 are grouped in pairs of two, and the axial position is maintained under the drive of the stator magnetic circuit of the axial bearing 6; thus, the axial bearing 6 is made into a structure without a thrust disk, saving space and reducing the mechanical property requirements.

[0028] The two second shaft sections 32 and the two third shaft sections 33 are both axially symmetrically distributed along the first shaft section 31. The second shaft section 32 and the third shaft section 33 are connected by a bevel transition to reduce the internal stress between different shaft sections.

[0029] A permanent magnet is arranged inside the first shaft section 31, a copper-clad layer 34 is arranged on the surface of the first shaft section 31, and the first shaft section 31 is connected to the drive end of the stator 2; the second shaft section 32 and the third shaft section 33 are respectively connected to the support end of the axial bearing 6 and the support end of the radial bearing 5. The copper-clad layer 34 is integrated with the shaft and has excellent mechanical properties, greatly improving the limits of the rotational speed and power of the high-speed motor. The thermal conductivity of copper is 10 times higher than that of carbon fiber and 6.5 times higher than that of nickel-based alloy, and there is also a great improvement in the heat dissipation of the motor. The copper-clad layer 34 includes a concave part 35 located in the middle and convex parts 36 located on both sides, and the width of the concave part 35 is the same as that of the drive end of the stator 2.

[0030] A radial magnetic bearing rotor assembly is arranged on the outer surface of the third shaft section 33, and the radial magnetic bearing rotor assembly is connected to the magnetic circuit support end of the radial bearing 5. The radial magnetic bearing rotor assembly and the stator magnetic field of the radial bearing 5 form a loop to make the rotor levitate under magnetic force.

[0031] The motor shaft 3 further includes a fourth shaft section 39, and the two fourth shaft sections 39 are respectively located outside the two third shaft sections 33; punching sheets axially stacked and attached to each other are shrink-fitted on the outer surface of the fourth shaft section 39, and the punching sheets on the fourth shaft section 39 are connected to the induction end of the axial sensor to detect the axial position of the motor shaft 3.

[0032] The motor shaft 3 further includes a fifth shaft section 30. The two fifth shaft sections 30 are respectively located outside the two fourth shaft sections 39, and the outer surface of the fifth shaft section 30 is matched with the inner ring of the non-magnetic radial bearing. When the motor is powered off, the magnetic forces provided by the radial bearing 5 and the axial bearing 6 disappear, and the motor shaft 3 drops to the position of the non-magnetic radial bearing and is supported to prevent the sudden drop and damage of the motor shaft 3.

[0033] The cylindrical outer surface of the fifth shaft section 30 is provided with end face teeth 301, and the end face teeth 301 are matched with the connection part of the impeller. The end face tooth structure 301 is automatically centered with the impeller to transmit torque. The outer end face of the fifth shaft section 30 is provided with screw holes, and the impeller is fixed on the screw holes and connected to the motor shaft 3.

Claims

1. A magnetic levitation high-speed asynchronous motor without a thrust disk, the motor comprising a housing (1), a stator (2), a motor shaft (3), a radial bearing (5) and an axial bearing (6); characterized in that, The motor shaft (3) includes a first shaft section (31), two second shaft sections (32) respectively located outside both ends of the first shaft section (31), and two third shaft sections (33) respectively located outside both ends of the second shaft sections (32); the cylindrical diameter of the second shaft section (32) is smaller than that of the first shaft section (31), and a first shaft shoulder (37) is formed on the outer end surface of the first shaft section (31) at the connection position between the second shaft section (32) and the first shaft section (31); the cylindrical diameter of the third shaft section (33) is smaller than that of the second shaft section (32), and a second shaft shoulder (38) is formed on the outer end surface of the second shaft section (32) at the connection position between the third shaft section (33) and the second shaft section (32); both the first shaft shoulder (37) and the second shaft shoulder (38) are magnetically conductive surfaces, and the first shaft shoulder (37) and the second shaft shoulder (38) are respectively connected to the stator magnetic circuit support ends of the axial bearing (6). The motor shaft (3) further includes a fourth shaft section (39) and a fifth shaft section (30), and the two fourth shaft sections (39) are respectively located outside the two third shaft sections (33); the outer surface of the fourth shaft section (39) is shrink-fitted with axially stacked and fitted laminations, and the laminations on the fourth shaft section (39) are connected to the induction end of the axial sensor; the two fifth shaft sections (30) are respectively located outside the two fourth shaft sections (39), and the outer surface of the fifth shaft section (30) is fitted with the inner ring of the non-magnetic radial bearing. A permanent magnet is arranged inside the first shaft section (31), a copper-clad layer (34) is arranged on the surface of the first shaft section (31), and the first shaft section (31) is connected to the driving end of the stator (2); the second shaft section (32) and the third shaft section (33) are respectively connected to the support end of the axial bearing (6) and the support end of the radial bearing (5), and the copper-clad layer (34) includes a concave portion (35) located in the middle and convex portions (36) located on both sides, and the width of the concave portion (35) is the same as that of the driving end of the stator (2).

2. The magnetic levitation high-speed asynchronous motor without a thrust disk according to claim 1, characterized in that The two second shaft sections (32) and the two third shaft sections (33) are both axially symmetrically distributed along the first shaft section (31).

3. The magnetic levitation high-speed induction motor without a thrust disk according to claim 1, wherein The second shaft section (32) and the third shaft section (33) are connected by a bevel transition.

4. The magnetic levitation high-speed asynchronous motor without a thrust disk according to claim 1, characterized in that, A radial magnetic bearing rotor assembly is arranged on the outer surface of the third shaft section (33), and the radial magnetic bearing rotor assembly is connected to the magnetic circuit support end of the radial bearing (5).

5. The magnetic levitation high-speed asynchronous motor without a thrust disk according to claim 1, characterized in that End teeth (301) are arranged on the cylindrical outer surface of the fifth shaft section (30), and the end teeth (301) are fitted with the connection part of the impeller.

6. The magnetic levitation high-speed induction motor without a thrust disk according to claim 1, characterized in that Screw holes are arranged on the outer end surface of the fifth shaft section (30), and the impeller is fixed on the screw holes and connected to the motor shaft (3).

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