Asymmetric axial magnetic suspension bearing

Abstract

The invention relates to an asymmetric axial magnetic suspension bearing which is characterized in that a rotating shaft is connected with a thrust disc, and an upper thrust disc stator and a lower thrust disc stator are respectively connected with a motor shell; a certain distance is formed between the opposite end surfaces of the upper thrust disc stator and the lower thrust disc stator and the thrust disc respectively; the outer diameter of the upper thrust disc stator cover plate is matched with the outer diameter of the upper thrust disc stator; the upper thrust disc stator cover plate is arranged on the upper thrust disc stator, so that the first coil is fixed in the upper thrust disc stator; the end face of the upper thrust disc stator cover plate is flush with the inner ring end face of the upper thrust disc stator. The outer diameter of the lower thrust disc stator cover plate is matched with the outer diameter of the lower thrust disc stator; the lower thrust disc stator cover plate is arranged on the lower thrust disc stator, so that the second coil is fixed in the lower thrust disc stator groove; the lower end face of the lower thrust disc stator cover plate is flush with the lower end face of the thrust disc, and the distance between the lower thrust disc stator cover plate and the upper thrust disc stator cover plate is larger than the gap between the lower thrust disc stator cover plate and the thrust disc.

Description

Technical Field

[0001] The invention relates to magnetic bearing technology, in particular to an asymmetric axial magnetic suspension bearing. Background Art

[0002] Existing motors are supported by mechanical bearings. Due to the friction of the mechanical bearings and the vibration of the rotor, the motors can only run at low speeds, with low power density and low efficiency. At the same time, mechanical bearings have high energy consumption, poor reliability, and serious noise and oil pollution.

[0003] High-speed motors supported by magnetic bearings eliminate friction and wear. Since magnetic bearings do not require lubrication, the speed of high-speed motors can reach tens of thousands of revolutions per minute. They have the advantages of high power density, high energy efficiency, small size, light weight, and fast response. They are ideal supporting components for the development of high-speed rotating power machinery in the future. Existing axial magnetic bearing solutions are mostly thrust disc single-sided force-bearing structures or thrust disc double-sided symmetrical force-bearing structures.

[0004] Figure 1 The figure shows a single-side force structure diagram of an existing axial magnetic bearing thrust plate. Figure 1 As shown, only one side of the thrust plate is subjected to the electromagnetic force, and the rotor is suspended after overcoming the rotor gravity and axial aerodynamic force. The required electromagnetic force is large and the number of coil turns is large, resulting in energy waste. At the same time, only the stator of the thrust plate on one side can be controlled and adjusted, which is not conducive to the stable operation of the rotor.

[0005] Figure 2 The figure shows a conventional axial magnetic bearing thrust plate with bilaterally symmetrical force structure. Figure 2 Although the double-sided force structure of the thrust plate can adjust the upper and lower stator currents of the thrust plate through the sensor feedback signal at any time to make the rotor run stably, it is still necessary to allocate a large bias current to overcome the rotor's own gravity and axial aerodynamic force to make the rotor suspended, resulting in energy waste. At the same time, the sensor is placed above the shaft 1, occupying the overall space. Summary of the invention

[0006] The object of the present invention is to provide an asymmetric axial magnetic bearing for solving the above-mentioned problems in the prior art.

[0007] The present invention discloses an asymmetric axial magnetic suspension bearing, which comprises: a rotating shaft, a thrust plate, an upper thrust plate stator, a first coil, a second coil, an upper thrust plate stator cover, a lower thrust plate stator, and a lower thrust plate stator cover; the rotating shaft is connected to the thrust plate, and the upper thrust plate stator and the lower thrust plate stator are respectively connected to the motor housing; the upper thrust plate stator and the lower thrust plate stator have a certain distance from the end faces opposite to the thrust plate; the upper thrust plate stator The outer diameter of the cover plate matches the outer diameter of the upper thrust plate stator, and the inner diameter of the upper thrust plate stator cover plate is smaller than the outer diameter of the thrust plate; the upper thrust plate stator cover plate is arranged on the upper thrust plate stator, and the upper thrust plate stator cover plate is fastened to the upper thrust plate stator, so that the first coil is fixed in the space surrounded by the upper thrust plate stator and one end face of the upper thrust plate stator cover plate; the other end face of the upper thrust plate stator cover plate is flush with the inner ring end face of the upper thrust plate stator; the lower thrust plate stator The outer diameter of the cover plate matches the outer diameter of the lower thrust plate stator, and the inner diameter of the lower thrust plate stator cover plate is larger than the outer diameter of the thrust plate; the lower thrust plate stator cover plate is arranged on the lower thrust plate stator, and the lower thrust plate stator cover plate is fastened to the lower thrust plate stator, so that the second coil is fixed in the space surrounded by the lower thrust plate stator and one end face of the lower thrust plate stator cover plate, and the lower end face of the thrust plate is flush with the end face of the lower thrust plate stator cover plate, and the lower thrust plate stator cover plate is fixed to the lower thrust plate stator. The distance between the plate and the upper thrust plate stator cover is greater than the gap between the lower thrust plate stator cover and the thrust plate; when the current changes, a magnetic circuit is formed between the upper thrust plate stator, the upper thrust plate stator cover and the thrust plate, and the thrust plate is subjected to an upward magnetic pull, while a magnetic circuit is formed between the lower thrust plate stator, the lower thrust plate stator cover and the thrust plate, and the thrust plate is subjected to a downward magnetic pull; the difference in the electromagnetic pull received by the thrust plate is equal to the gravity of the rotor itself.

[0008] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, it also includes: a first sensor and a second sensor, the first sensor is embedded in the upper thrust plate stator, and the second sensor is embedded in the lower thrust plate stator, the first sensor and the second sensor are symmetrically arranged for detecting the rotor position.

[0009] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the first sensor and the second sensor are respectively 0.5-0.6 mm away from the upper and lower end surfaces of the thrust plate.

[0010] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the rotating shaft and the thrust plate are fixed by shrink fitting or threaded connection; the upper thrust plate stator and the lower thrust plate stator are fastened to the outer shell by shrink fitting or screws respectively; the lower thrust plate stator cover plate is fastened to the lower thrust plate stator by screws at the outer ring, and the upper thrust plate stator cover plate is fastened to the upper thrust plate stator by screws at the outer ring; the upper thrust plate stator and the lower thrust plate stator are respectively 0.3 to 0.6 mm away from the end faces opposite to the thrust plate.

[0011] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the first coil and the second coil are made of copper wire material, the first coil is arranged in the stator slot of the upper thrust plate, and the second coil is arranged in the stator slot of the lower thrust plate.

[0012] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the lower thrust plate stator, the upper thrust plate stator, the upper thrust plate stator cover, the lower thrust plate stator cover and the thrust plate are made of soft magnetic materials.

[0013] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, when current is passed through the first coil, the path of the magnetic lines of force is the upper thrust plate stator, the upper thrust plate stator cover, enters the thrust plate, and then returns to the upper thrust plate stator, forming a loop, which produces an upward suction effect on the rotor; when current is passed through the second coil, the path of the magnetic lines of force is the lower thrust plate stator, the lower thrust plate stator cover, enters the thrust plate, and then returns to the lower thrust plate stator, forming a loop, which produces a downward suction effect on the rotor.

[0014] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the upper thrust plate stator cover plate, the lower thrust plate stator cover plate and the end surface area of ​​the thrust plate are matched, so that when current is passed through the first coil or the second coil, the axial upward pulling force of the thrust plate by the thrust plate stator is greater than the axial downward pulling force, so that the difference between the upper and lower pulling forces on the thrust plate is equal to the gravity of the rotor itself, achieving force balance and allowing the rotor to be suspended and operate stably.

[0015] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the distance between the upper thrust plate stator and one end surface of the thrust plate is smaller than the distance between the lower thrust plate stator and the other end surface of the thrust plate.

[0016] According to an embodiment of the asymmetric axial magnetic bearing of the present invention, the number of turns of the first wire is different from the number of turns of the second wire, so as to adjust the difference between the upper and lower pulling forces on the thrust plate.

[0017] The asymmetric axial magnetic suspension bearing of the present invention has the advantages of low loss, simple control and small space occupation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure shows a single-side force structure diagram of an existing axial magnetic bearing thrust plate;

[0019] Figure 2 The figure shows a bilaterally symmetrical force structure diagram of a thrust plate of an existing axial magnetic bearing;

[0020] Figure 3 Shown is a schematic diagram of an asymmetric axial magnetic bearing of the present invention;

[0021] Figure 4The figure shows a schematic diagram of the position relationship of the asymmetric axial magnetic bearing of the present invention;

[0022] Figure 5 Shown is a stereoscopic view of a single axial magnetic bearing of the present invention;

[0023] Figure 6 Shown is a system explosion diagram of the asymmetric axial magnetic bearing of the present invention;

[0024] Figure 7 Shown is a schematic diagram of the distance between the thrust plate stator cover and the thrust plate end face;

[0025] Figure 8 Shown is a schematic diagram of the magnetic circuit of the asymmetric axial magnetic suspension bearing of the present invention;

[0026] Fig. 9 Shown is a schematic diagram of the axial force of the thrust plate;

[0027] Fig.10 Shown is a schematic diagram of the distance between the upper thrust plate stator and the lower thrust plate stator and the end surface of the thrust plate;

[0028] Fig.11 Shown is a schematic diagram of the number of turns of the first wire and the number of turns of the second wire. DETAILED DESCRIPTION

[0029] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0030] Figure 3 FIG. 1 is a schematic diagram of an asymmetric axial magnetic bearing according to the present invention. Figure 4 The figure shows the position relationship diagram of the asymmetric axial magnetic bearing of the present invention. Figure 5 FIG. 1 is a three-dimensional diagram of a single axial magnetic bearing according to the present invention. Figure 6 The system explosion diagram of the asymmetric axial magnetic bearing of the present invention is shown as follows: Figures 3 to 6 As shown, the asymmetric axial magnetic bearing of the present invention includes: a rotating shaft 1, a thrust plate 2, an upper thrust plate stator 3, a first coil 4, a second coil 8, an upper thrust plate stator cover 5, a lower thrust plate stator 7, a lower thrust plate stator cover 9, a first sensor 6 and a second sensor 10.

[0031] like Figures 3 to 6As shown, the rotating shaft 1 and the thrust plate 2 are fixed by shrink fitting or threaded connection. The upper thrust plate stator 3 and the lower thrust plate stator 7 are fastened to the motor housing by shrink fitting or screws 11 respectively. The end faces of the upper thrust plate stator 3 and the lower thrust plate stator 7 relative to the thrust plate 2 are 0.3 to 0.6 mm apart. The first sensor 6 is embedded in the upper thrust plate stator 3, and the second sensor 10 is embedded in the lower thrust plate stator 7. The first sensor 6 and the second sensor 10 are symmetrically arranged, 0.5 to 0.6 mm away from the end face of the thrust plate 2, respectively, for real-time detection of the rotating shaft position, and feedback of the current signal to adjust the rotor position from time to time, so that the rotor can operate stably in suspension.

[0032] Figure 7 The figure shows the distance between the thrust plate stator cover and the thrust plate end face. Figures 3 to 7 As shown, the outer diameter of the upper thrust plate stator cover plate 5 matches the outer diameter of the upper thrust plate stator 3, and the inner diameter of the upper thrust plate stator cover plate 5 is slightly smaller than the outer diameter of the thrust plate 2. The upper thrust plate stator cover plate 5 is arranged on the upper thrust plate stator 3, and is fastened to the upper thrust plate stator 3 by screws at the outer ring of the upper thrust plate stator cover plate 5, so that the first coil 4 is fixed in the groove of the upper thrust plate stator 3. The end face of the upper thrust plate stator cover plate 5 is flush with the inner ring end face of the upper thrust plate stator 3, and is 0.3 to 0.6 mm away from the upper end face of the thrust plate 2.

[0033] like Figures 3 to 7 As shown, the outer diameter of the lower thrust disc stator cover plate 9 matches the outer diameter of the lower thrust disc stator 7, and the inner diameter of the lower thrust disc stator cover plate 9 is slightly larger than the outer diameter of the thrust disc 2, for example, it can be 1 to 2 mm. The lower thrust disc stator cover plate 9 is located on the lower thrust disc stator 7, and is fastened to the lower thrust disc stator 7 by screws at the outer ring of the lower thrust disc stator cover plate 9, so that the second coil 8 is fixed in the slot of the lower thrust disc stator 7; the lower end surface of the lower thrust disc stator cover plate 9 is flush with the lower end surface of the thrust disc, and after being flush, the lower thrust disc stator cover plate 9 and the thrust disc 2 are only subjected to radial force, avoiding pulling force, and the outer diameter of the thrust disc 2 can be further reduced. The distance between the lower thrust disc stator cover plate 9 and the upper thrust disc stator cover plate 5 is greater than the gap between the lower thrust disc stator cover plate 9 and the thrust disc 2, so that the magnetic circuits of the upper thrust disc stator 3 and the lower thrust disc stator 7 do not interfere, reducing magnetic leakage. This structure can make the difference between the upper and lower electromagnetic pulling forces on the thrust plate 2 equal to the weight of the rotor itself, and form an effective magnetic circuit between the lower thrust plate stator 7, the lower thrust plate stator cover plate 9, and the thrust plate 2; and an effective magnetic circuit is also formed between the upper thrust plate stator 3, the upper thrust plate stator cover plate 5, and the thrust plate 2. The magnetic circuits of the upper and lower magnetic bearings (thrust plate stator assembly) complement each other to reduce ineffective magnetic leakage.

[0034] like Figures 3 to 7As shown, the first coil 4 and the second coil 8 are both copper wires wrapped in the thrust plate stator slot. The lower thrust plate stator 7, the upper thrust plate stator 3, the upper thrust plate stator cover 5, the lower thrust plate stator cover 9 and the thrust plate 2 are all made of soft magnetic materials.

[0035] Figure 8 FIG. 1 is a schematic diagram of the magnetic circuit of the asymmetric axial magnetic bearing of the present invention. Figure 8 As shown in the figure (the stereoscopic figure is a rotation along the Z axis), the lower thrust plate stator 7, the upper thrust plate stator 3, the upper thrust plate stator cover 5, the lower thrust plate stator cover 9 and the thrust plate 2 are all magnetic conductive materials. When current is passed through the first coil 4, a magnetic field will be generated around it, and the magnetic lines of force will enter the thrust plate 2 along, for example, the upper thrust plate stator 3 and the upper thrust plate stator cover 5, and then return to the upper thrust plate stator 3 to form a loop, which will produce an upward suction effect on the thrust plate. When current is passed through the second coil 8, the magnetic lines of force will enter the thrust plate 2 along the lower thrust plate stator 7 and the lower thrust plate stator cover 9, and then return to the lower thrust plate stator 7 to form a loop, which will produce a downward suction effect on the thrust plate. The position of the thrust plate 2 is constantly detected by the sensor provided to feedback and adjust the current of the upper and lower thrust plate stators, and then adjust the force of the thrust plate 2, so that the thrust plate 2 is always stably suspended between the upper and lower thrust plate stators.

[0036] Fig. 9 The diagram shows the axial force of the thrust plate. Fig. 9 As shown, due to the asymmetric structure of the upper thrust plate stator cover plate 5 and the lower thrust plate stator cover plate 9, the axial upward pulling force of the thrust plate stator on the thrust plate 2 is greater than the axial downward pulling force, so that the difference between the upper and lower pulling forces on the thrust plate is equal to the gravity of the rotor itself, achieving force balance and allowing the rotor to operate stably in suspension.

[0037] like Fig. 9 As shown, the axial force analysis of the thrust plate includes: the thrust plate 2 and the rotor's own gravity, and the downward magnetic pull F generated by the lower thrust plate stator 7. 下 , the upper thrust plate stator 3 generates an upward magnetic pull F 上1 and F 上2 The simplified formula of magnetic pull is F = 1 / 2u*B2S, where u is the air magnetic permeability, B is the air gap magnetic density, and S is the annular area of ​​the thrust plate and the thrust plate stator. Therefore, according to the present invention, those skilled in the art can reasonably select the matching area between the upper and lower thrust plate covers and the end surface of the thrust plate 2. For example, in this embodiment, the upper thrust plate stator cover 5 increases the matching area with the thrust plate 2, so that the thrust plate 2 is subjected to an additional upward magnetic pull F. 上2 , used to offset the weight of the rotor itself.

[0038] Fig.10 The figure shows the distance between the upper thrust plate stator and the lower thrust plate stator and the end face of the thrust plate. Fig.10As shown, for an embodiment, the present invention can be further provided that the distance between the upper thrust plate stator 3 and the end surface of the thrust plate 2 is smaller than the distance between the lower thrust plate stator 7 and the end surface of the thrust plate 2, and by affecting the air gap magnetic density, the difference between the upper and lower pulling forces on the thrust plate 2 is finely adjusted to be equal to the rotor gravity.

[0039] Fig.11 The figure shows the schematic diagram of the number of turns of the first wire and the number of turns of the second wire. Fig.11 As shown, for another embodiment, the present invention can also adjust the number of turns of the first coil 4 and the second coil 8. For example, the number of turns of the first coil 4 is greater than the number of turns of the second coil 8, and the difference between the upper and lower pulling forces on the thrust plate 2 is further adjusted to be equal to the rotor gravity.

[0040] The present invention uses an asymmetric design of the upper and lower thrust disc stator covers to distribute a smaller bias current to overcome the rotor's own gravity and make it suspended, saving energy. The thrust disc has a double-sided force structure, so that the difference between the upper and lower pulling forces on the thrust disc is equal to the rotor's own gravity, and the rotor runs stably, which is convenient for control and adjustment. The asymmetric design of the upper and lower thrust disc stator covers makes the difference between the upper and lower pulling forces on the thrust disc equal to the rotor's own gravity, and the rotor runs stably, which is convenient for control and adjustment. At the same time, the sensor is located in the thrust disc stator, saving overall space.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An asymmetric axial magnetic bearing, characterized in that: include: Rotating shaft, thrust plate, upper thrust plate stator, first coil package, second coil package, upper thrust plate stator cover, lower thrust plate stator, lower thrust plate stator cover; The rotating shaft is connected to the thrust plate, and the upper thrust plate stator and the lower thrust plate stator are respectively connected to the motor housing; the upper thrust plate stator, the lower thrust plate stator and the end faces opposite to the thrust plate are respectively at a certain distance; The outer diameter of the upper thrust plate stator cover plate matches the outer diameter of the upper thrust plate stator, and the inner diameter of the upper thrust plate stator cover plate is smaller than the outer diameter of the thrust plate; the upper thrust plate stator cover plate is arranged on the upper thrust plate stator, and the upper thrust plate stator cover plate is fastened to the upper thrust plate stator, so that the first coil is fixed in the space surrounded by the upper thrust plate stator and one end surface of the upper thrust plate stator cover plate; the other end surface of the upper thrust plate stator cover plate is flush with the inner ring end surface of the upper thrust plate stator; The outer diameter of the lower thrust plate stator cover plate matches the outer diameter of the lower thrust plate stator, and the inner diameter of the lower thrust plate stator cover plate is larger than the outer diameter of the thrust plate; the lower thrust plate stator cover plate is arranged on the lower thrust plate stator, and the lower thrust plate stator cover plate is fastened to the lower thrust plate stator, so that the second coil is fixed in the space surrounded by the lower thrust plate stator and one end surface of the lower thrust plate stator cover plate, and the lower end surface of the thrust plate is flush with the end surface of the lower thrust plate stator cover plate, and the distance between the lower thrust plate stator cover plate and the upper thrust plate stator cover plate is larger than the gap between the lower thrust plate stator cover plate and the thrust plate; When the current changes, a magnetic circuit is formed between the upper thrust plate stator, the upper thrust plate stator cover and the thrust plate, and the thrust plate is subjected to an upward magnetic pull, while a magnetic circuit is formed between the lower thrust plate stator, the lower thrust plate stator cover and the thrust plate, and the thrust plate is subjected to a downward magnetic pull; the difference in the electromagnetic pull on the thrust plate is equal to the gravity of the rotor itself.

2. The asymmetric axial magnetic bearing according to claim 1, characterized in that: Also includes: The first sensor and the second sensor are embedded in the upper thrust plate stator and the second sensor is embedded in the lower thrust plate stator. The first sensor and the second sensor are symmetrically arranged and used for detecting the rotor position.

3. The asymmetric axial magnetic bearing according to claim 2, characterized in that: The first sensor and the second sensor are respectively 0.5 to 0.6 mm away from the upper and lower end surfaces of the thrust plate.

4. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The rotating shaft and the thrust plate are fixed by shrink fitting or threaded connection; The upper thrust plate stator and the lower thrust plate stator are fastened to the housing by shrink fitting or screws respectively; The outer ring of the stator cover of the lower thrust plate is fastened to the stator of the lower thrust plate by screws, and the outer ring of the stator cover of the upper thrust plate is fastened to the stator of the upper thrust plate by screws; The upper thrust plate stator and the lower thrust plate stator are respectively 0.3-0.6 mm away from the end faces opposite to the thrust plates.

5. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The first wire package and the second wire package are made of copper wire material. The first wire package is arranged in the stator slot of the upper thrust plate, and the second wire package is arranged in the stator slot of the lower thrust plate.

6. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The lower thrust plate stator, the upper thrust plate stator, the upper thrust plate stator cover plate, the lower thrust plate stator cover plate and the thrust plate are made of soft magnetic materials.

7. The asymmetric axial magnetic bearing according to claim 1, characterized in that: When current is passed through the first coil, the path of the magnetic lines of force is the upper thrust plate stator, the upper thrust plate stator cover, into the thrust plate, and then back to the upper thrust plate stator, forming a loop, which produces an upward suction effect on the rotor; When current flows through the second coil, the path of the magnetic lines of force is the lower thrust plate stator, the lower thrust plate stator cover, into the thrust plate, and then back to the lower thrust plate stator, forming a loop, which produces a downward suction effect on the rotor.

8. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The upper thrust plate stator cover plate, the lower thrust plate stator cover plate and the end surface area of ​​the thrust plate are matched so that when current is passed through the first coil or the second coil, the axial upward pulling force of the thrust plate by the thrust plate stator is greater than the axial downward pulling force, so that the difference between the upper and lower pulling forces on the thrust plate is equal to the gravity of the rotor itself, achieving force balance and allowing the rotor to operate stably in suspension.

9. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The distance between the upper thrust plate stator and one end surface of the thrust plate is smaller than the distance between the lower thrust plate stator and the other end surface of the thrust plate.

10. The asymmetric axial magnetic bearing according to claim 1, characterized in that: The number of turns of the first wire is different from the number of turns of the second wire to adjust the difference between the upper and lower pulling forces on the thrust plate.

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