CN103758865A - Permanent magnet biased unilateral axial magnetic suspension bearing - Google Patents

Abstract

The invention relates to a permanent magnetic bias single-side axial magnetic suspension bearing, which is generally used in pairs and belongs to a hybrid magnetic suspension bearing. It puts the inner magnetic pole of the stator and the outer magnetic pole of the stator on the side of the end thrust disc; uses the stepped surface of the end thrust disc as the magnetic pole surface; The thrust disc air gap establishes a bias magnetic field and a control magnetic field, and realizes axial displacement control after being used in pairs; and cooling holes are opened on the inner and outer magnetic poles of the stator. This kind of permanent magnetic bias magnetic suspension bearing is easy to install and disassemble. Its thrust plate has a small radius, low power consumption, and small volume. It can overcome the static bias force on the rotor and has good cooling capacity. It is used in various magnetic suspension systems. All have broad prospects, and are especially suitable for high-speed compressors, expanders and other occasions where wind loss is the main loss of magnetic suspension bearings.

Description

Permanent Magnetic Bias Unilateral Axial Magnetic Suspension Bearing

technical field

The invention relates to a magnetic suspension bearing, in particular to a permanent magnetic bias single-side axial magnetic suspension bearing.

Background technique

The basic principle of the magnetic suspension bearing is to use the magnetic force between the stator core and the rotor core to realize the non-contact support of the rotor. Since the magnetic force does not require a medium, there is no mechanical contact between the stator and the rotor.

Magnetic suspension bearings have the following main advantages: (1) The rotor can operate at ultra-high speeds, and the rotational speed is theoretically limited only by the rotor material; Bacterial space, vacuum system, low temperature environment, etc., even in high temperature environment; (3) Bearing loss is very low, only 1/20 to 1/5 of traditional ball bearings or sliding bearings; (4) Due to no mechanical wear, It offers lower maintenance costs and longer life in harsh environments.

Magnetic suspension bearings are divided into permanent magnet type, electromagnetic bias type and permanent magnet bias type according to the way the magnetic field is established.

The permanent magnet type magnetic suspension bearing uses the attraction or repulsion of the magnetic material to realize the suspension of the rotor. The structure is simple, but its damping is generally small.

The electromagnetic bias type magnetic suspension bearing generates a bias magnetic field in the air gap through current bias, and the alternating current winding generates a control magnetic field in the air gap. The magnetic force generated by the superposition of the bias magnetic field and the control magnetic field can be precisely controlled according to the feedback signal, so that To realize the control of one or some degrees of freedom of the rotor, the stiffness and damping of this type of magnetic suspension bearing can be adjusted. However, since the bias current is much larger than the control current under stable conditions, more power loss is caused in the winding, and the volume and weight required to generate the unit bearing capacity are relatively large.

Compared with the magnetic bias type magnetic suspension bearing, the permanent magnetic bias type magnetic suspension bearing uses the permanent magnet instead of the bias coil to generate the required bias magnetic field in the air gap, which can not only greatly reduce energy consumption, but also reduce the The temperature rise of the magnetic suspension bearing is small, and the volume and weight of the magnetic suspension bearing can also be reduced. This has an irreplaceable advantage in some fields that have higher requirements for magnetic suspension power consumption, volume, performance, etc. Permanent magnetic bias magnetic suspension bearing technology has become an important direction in magnetic suspension bearing technology.

Wind loss is a kind of gas friction loss. Wind losses are the major losses in compressors and expanders due to high gas pressure (where the gas pressure is high), especially axial bearing thrust discs, which have relatively large diameters and surface velocities. It is generally believed that wind loss is basically proportional to the cube of the peripheral velocity. Therefore, a magnetic bearing with a smaller diameter thrust plate can greatly reduce wind loss.

In most compressors and expanders, it is common for aerodynamic forces to generate large offset axial forces on the rotor. Therefore, a magnetic suspension bearing capable of generating static offset axial force and generating less power consumption can better meet the requirements of use.

Contents of the invention

The main purpose of the present invention is to provide a permanent magnetic bias single-side axial magnetic suspension bearing which is easy to install, has low power consumption, small volume and is convenient for generating bias magnetic force.

In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: comprising a stepped main shaft and a stepped end thrust disc set on the step surface of the main shaft, and the large end surface of the end thrust disc is installed close to the step of the main shaft; Stator inner magnetic poles and stator outer magnetic poles are respectively installed on the positions corresponding to the inner and outer step surfaces of the stepped end thrust discs. The stator inner magnetic poles have a stepped structure, the stator outer magnetic poles have a circular structure, and the stator inner The diameter of the magnetic pole is equal to that of the outer magnetic pole of the stator, and a step-shaped cavity is formed between the outer magnetic pole of the stator and the inner magnetic pole of the stator. A ring-shaped permanent magnet is installed on the end face of the small step surface of the inner magnetic pole of the stator, and a control device is installed in the outer magnetic pole of the stator. For the winding, a permanent magnet shield is installed on the outer side of the annular permanent magnet, and an annular non-magnetic gasket is installed on the surface where the outer magnetic pole of the stator is in contact with the inner magnetic pole of the stator.

A plurality of cooling holes for stator outer magnetic poles and stator inner magnetic pole cooling holes uniformly distributed in the circumferential direction are opened at the outer sides of the outer magnetic poles of the stator and the inner magnetic poles of the stator at the same radius.

There is a gap between the inner magnetic pole of the stator and the inner stepped surface of the end thrust disk, the outer magnetic pole of the stator and the outer stepped circular surface of the inner stepped surface of the end thrust disk, and the gap width is between 0.3 and 1.5mm; There is a radial gap between the inner magnetic pole and the main shaft, and the gap width is greater than or equal to 0.5mm; there is a radial gap between the outer magnetic pole of the stator and the small cylindrical surface of the end thrust disk, and the gap is greater than or equal to 1.0mm.

The end thrust plate, the heat dissipation holes of the inner magnetic pole of the stator, and the soft magnetic material of the inner magnetic pole of the stator; the main shaft, the permanent magnet shield; the annular permanent magnet is made of rare earth permanent magnetic material or ferrite permanent magnetic material.

The permanent magnet bias unilateral axial magnetic suspension bearings of the present invention can be used in pairs, and the axially magnetized annular permanent magnet passes through the inner magnetic pole of the stator, the end thrust disc, the outer magnetic pole of the stator, the gap between the inner and outer magnetic poles of the stator and the permanent magnet shield. The cover forms a bias magnetic field in the air gap between the inner magnetic pole of the stator and the inner step surface of the end thrust disk and the air gap between the outer magnetic pole of the stator and the inner step surface of the end thrust disk; after the control winding is fed with current, The air gap between the inner magnetic pole of the stator and the inner step surface of the end thrust disc and the inner step surface of the outer magnetic pole of the stator and the inner step surface of the end thrust disc through the inner magnetic pole of the stator, the annular non-magnetic gasket, the outer magnetic pole of the stator and the end thrust disc A control magnetic field is formed in the air gap between them. The above-mentioned magnetic suspension bearings are generally used in pairs, which are respectively installed at the two ends of the main shaft.

The permanent magnetic bias unilateral axial magnetic suspension bearing of the present invention mainly has the following advantages: (1) The stator part of the present invention can be installed from one side of the main shaft, which is convenient for installation and disassembly; (2) The present invention utilizes permanent magnets to generate Bias flux, especially when used in pairs, if there is a static bias force acting on the rotor, the different bias fluxes generated on both sides can offset or partially offset the static bias force, reducing work (3) The diameter of the thrust plate at the end of the axial magnetic suspension bearing described in the present invention is small, which can be equal to or slightly larger than the maximum diameter of the main shaft, which not only reduces the strength requirements of the rotor part of the axial magnetic suspension bearing, but also reduces the wind loss It is also very small; (4) The permanent magnet is used to generate the bias flux. Compared with the full electromagnetic bearing, the bias excitation current that accounts for the main component of the coil current is eliminated, and the copper loss of the winding and the loss of the control power amplifier are reduced. Therefore, the power consumption (5) The magnetic field generated by the axial magnetic suspension bearing of the present invention only changes in size, but has no polarity change, and the iron loss is also very small; (6) In the present invention, the permanent magnet magnetic circuit is separated from the control magnetic circuit , which makes the reluctance of the control magnetic circuit very small, and a small current can generate a large magnetic flux; (7) The permanent magnet bias unilateral axial magnetic suspension bearing has cooling holes, which improves the cooling capacity of the bearing and allows higher Winding temperature rise.

The invention is easy to install and disassemble, the radius of the thrust plate is small, the power consumption is small, the volume is small, the static bias force on the rotor can be overcome, and the cooling capacity is good. It has broad prospects in various magnetic levitation systems, and especially It is suitable for applications where wind loss is the main loss of magnetic suspension bearings such as high-speed compressors and expanders.

Description of drawings

Fig. 1 is a schematic structural view of the permanent magnetic bias single-side axial magnetic suspension bearing of the present invention.

Label name in Fig. 1: 1, main shaft. 2. End thrust disc. 3. Permanent magnet shield. 4. Ring permanent magnet. 5. Cooling holes for outer magnetic poles of the stator. 6. The outer magnetic pole of the stator. 7. Annular non-magnetic gasket. 8. Control winding. 9. Cooling holes for magnetic poles in the stator. 10. Magnetic poles inside the stator. The dotted line with hollow arrows represents the permanent magnet bias field, and the solid line with solid arrows represents the magnetic field generated by the control winding.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the end thrust plate 2 in the figure, the stator inner magnetic pole cooling hole 9, and the stator inner magnetic pole 10 are made of soft magnetic materials; the main shaft 1, the permanent magnet shield 3, and the annular non-magnetic gasket 7 are non-conductive Magnetic material; the annular permanent magnet 4 is a rare earth permanent magnet material or a ferrite permanent magnet material. The large end surface of the end thrust disc 2 is installed close to the step of the main shaft 1; the annular permanent magnet 4 is installed on the cylindrical end surface of the inner magnetic pole 10 of the stator, the permanent magnet shield 3 is installed on the cylindrical end surface and the side surface of the inner magnetic pole 10 of the stator, and the annular permanent magnet 4 Between and in contact with the inner magnetic pole 10 of the stator and the permanent magnet shield 3; the control winding 8 is installed in the cylinder of the outer magnetic pole 6 of the stator, and there is a gap with the permanent magnet shield 3; the outer magnetic pole 6 of the stator passes through The annular non-magnetic gasket 7 is installed on the inner magnetic pole 10 of the stator, and the two sides of the annular non-magnetic gasket 7 are respectively in contact with the outer magnetic pole 6 of the stator and the inner magnetic pole 10 of the stator; the permanent magnet shield 3, the annular permanent magnet 4 and the control winding 8 are all in the cavity formed by the stator outer magnetic pole 6, the annular non-magnetic gasket 7 and the stator inner magnetic pole 10; the stator outer magnetic pole 6 and the stator inner magnetic pole 10 have several circumferentially evenly distributed cooling holes at the same radius on the outside structure, respectively stator outer magnetic pole cooling holes 5 and stator inner magnetic pole cooling holes 9; the main shaft 1 is located in the center hole of the stator inner magnetic pole 10 and the stator outer magnetic pole 6, and the stator inner magnetic pole 10 and the stator outer magnetic pole 6 are placed in the end thrust On one side of the disc 2, they respectively face the inner and outer stepped surfaces of the end thrust disc 2.

The stator inner magnetic pole 10 of the present invention is a stepped structure, the stator outer magnetic pole 6 is a ring-shaped structure, and the stator inner magnetic pole 10 is equal to the stator outer magnetic pole 6 in diameter, and a step is formed between the stator outer magnetic pole 6 and the stator inner magnetic pole 10 shaped cavity, an annular permanent magnet 4 is installed on the end surface of the small step surface of the inner magnetic pole 10 of the stator, and a control winding 8 is installed in the outer magnetic pole 6 of the stator. There is a gap between the inner magnetic pole 10 of the stator and the inner stepped surface of the end thrust disk 2, and the outer stepped annular surface of the stator outer magnetic pole 6 and the inner stepped surface of the end thrust disk 2, and the gap width is between 0.3 and 1.5mm; There is a radial gap between the stator inner magnetic pole 10 and the main shaft 1, and the gap width is greater than or equal to 0.5mm; there is a radial gap between the stator outer magnetic pole 6 and the small cylindrical surface of the end thrust disk 2, and the gap is greater than or equal to 1.0mm.

The axially magnetized annular permanent magnet 4 in Fig. 1 passes through the inner magnetic pole 10 of the stator, the end thrust disc 2, the outer magnetic pole 6 of the stator, the gap between the inner and outer magnetic poles of the stator, the permanent magnet shield 3 and the inner magnetic pole 6 of the stator and the end The air gap between the inner step surface of the thrust disc 2 and the air gap between the outer magnetic pole 6 of the stator and the inner step surface of the end thrust disc 2 form a permanent magnet bias magnetic field circuit, as shown by the single arrow in Figure 1; the control winding 8 After the current is applied, it passes through the inner magnetic pole 10 of the stator, the annular non-magnetic gasket 7, the outer magnetic pole 6 of the stator, the end thrust disc 2 and the air gap between the inner magnetic pole 6 of the stator and the inner step surface of the end thrust disc 2 , the air gap between the outer magnetic poles of the stator and the inner step surface of the end thrust disc 3 forms a control magnetic field loop, as shown by the double arrows in FIG. 1 . The above-mentioned magnetic suspension bearings are generally used in pairs, and they are respectively installed on the two ends of the main shaft (the structure of the suspension bearing on the right shaft is the same, not shown).

If there is no static bias force acting on the rotor main shaft 1, the above-mentioned magnetic suspension bearings used in pairs can be designed with the same parameters. Its basic working principle is: when the main shaft 1 is in a balanced position, the air gaps at both ends are equal, and the left and right stators generate the same suction force on the rotor. If the main shaft 1 is subjected to a rightward external disturbance force at this time, the main shaft will deviate from the equilibrium position and move to the right, so that the bias magnetic flux of the left axial magnetic suspension bearing decreases, and the bias magnetic flux of the right axial magnetic suspension bearing increases; at the same time The air gap between the inner and outer magnetic poles 1 of the left magnetic suspension bearing stator and the end thrust disk 2 increases, and the air gap between the inner and outer magnetic poles of the right magnetic suspension bearing stator and the end thrust disk decreases. Since the magnetic attraction force is proportional to the square of the magnetic flux when the magnetic pole area is constant, the magnetic bearing on the right side has a greater attraction to the rotor main shaft 1 than the left side. If the control winding has no current, the main shaft 1 will not return to the equilibrium position. At this time, if the displacement sensor or other type of sensor detects this change and transmits it to the controller, then the controller converts this signal into a control signal after calculation, and the power amplifier amplifies the control signal to obtain the corresponding in the control winding. control current. After the current passes through the control winding, a control magnetic field is established in the air gap between the stator pole and the end thrust disc. The established control magnetic field is superimposed with the bias magnetic field to increase the magnetic flux in the left air gap and decrease the magnetic flux in the right air gap to generate a leftward force to pull the main shaft 1 back to the equilibrium position; similarly, when the main shaft is subjected to a leftward force When external disturbance occurs, the permanent magnetic bias axial magnetic suspension bearing with negative feedback adjusts the magnetic flux of the air gaps on both sides by controlling the current in the winding, so that the main shaft is always kept in a balanced position.

When there is a static bias force acting on the rotor main shaft 1, a difference can be made in the air gap bias flux of the left and right axial magnetic suspension bearings to partially or completely offset the static bias force. If the static bias force is to the right, the left air gap bias magnetic flux is greater than the right; otherwise, the right air gap bias magnetic flux is greater than the left. The basic working principle of magnetic suspension bearings with and without static bias force is the same. Both adopt permanent magnet bias axial magnetic suspension bearings with negative feedback to adjust the magnetic flux of the air gap on both sides by controlling the current in the winding, so that the main shaft 1 always maintains in a balanced position.

Claims (4)

1. A permanent magnetic offset unilateral axial magnetic suspension bearing, characterized in that it includes a stepped main shaft (1) and a stepped end thrust plate (2) set on the stepped surface of the main shaft (1), and the end The large end face of the upper thrust disc (2) is installed close to the steps of the main shaft (1); on the main shaft (1) corresponding to the inner and outer step surfaces of the stepped end thrust disc (2), the inner magnetic poles of the stator ( 10) and the stator outer magnetic pole (6), the stator inner magnetic pole (10) is a stepped structure, the stator outer magnetic pole (6) is a circular structure, and the stator inner magnetic pole (10) and the stator outer magnetic pole (6) The diameters are equal, a step-shaped cavity is formed between the stator outer magnetic pole (6) and the stator inner magnetic pole (10), and an annular permanent magnet (4) is installed on the end face of the small stepped surface of the stator inner magnetic pole (10). A control winding (8) is installed inside the outer magnetic pole (6) of the stator, and a permanent magnet shield (3) is installed outside the annular permanent magnet (4). The outer magnetic pole (6) of the stator is in contact with the inner magnetic pole (10) of the stator. An annular non-magnetic pad (7) is also installed on the surface. 2. The permanent magnet bias single-sided axial magnetic suspension bearing according to claim 1, characterized in that: there are several stator poles (6) and stator inner poles (10) at the same radius on the outside. Circumferentially evenly distributed stator outer magnetic pole cooling holes (5) and stator inner magnetic pole cooling holes (9). 3. The permanent magnet bias single-sided axial magnetic suspension bearing according to claim 1, characterized in that: the inner magnetic pole (10) of the stator and the inner step surface of the thrust disc (2) at the end, the outer magnetic pole of the stator ( 6) There is a gap with the outer stepped circular surface of the end thrust disc (2), and the gap width is between 0.3 and 1.5 mm; there is a radial gap between the stator inner magnetic pole (10) and the main shaft (1), and the gap width is greater than or equal to 0.5 mm; there is a gap in the radial direction between the stator outer magnetic pole (6) and the smaller cylindrical surface of the end thrust disc (2), and the gap is greater than or equal to 1.0 mm. 4. The permanent magnet bias unilateral axial magnetic suspension bearing according to claim 1, 2 or 3, characterized in that: the end thrust plate (2), the magnetic pole cooling holes (9) in the stator, the The magnetic pole (10) is made of soft magnetic material; the main shaft (1), the permanent magnet shield (3); and the annular permanent magnet (4) is made of rare earth permanent magnetic material or ferrite permanent magnetic material.

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