A rotating speed detection device and a magnetic levitation bearing system

Abstract

The present disclosure relates to a kind of rotating speed detection device and magnetic suspension bearing system, belong to magnetic suspension motor technical field, rotating speed detection device includes control panel and silicon steel sheet assembly, silicon steel sheet assembly includes multiple layering silicon steel sheet groups;Along the length direction of silicon steel sheet assembly, silicon steel sheet assembly includes first end and second end, first end and second end are all set first probe and second probe;First probe and second probe are oppositely arranged at the same end of silicon steel sheet assembly, and the interval between first probe and second probe is greater than or equal to the thickness of silicon steel sheet group;Coil is wound on first probe and second probe respectively, and coil is connected with control panel.The rotating speed detection device of the present disclosure has strong anti-interference ability, strong output signal, wide measurement range, low maintenance cost, and the operation of rotating speed detection device does not need mechanical action, does not need lubrication, compact structure, easy to install.

Description

A speed detection device and a magnetic levitation bearing system Technical Field

[0001] This disclosure relates to the field of magnetic levitation motor technology, and in particular to a speed detection device and a magnetic levitation bearing system. Background Technology

[0002] Speed ​​detection of magnetic levitation motors is one of the important detection parameters and references for controlling them. The accuracy, stability, and anti-interference requirements for speed detection of magnetic levitation motors are very high. Existing methods for speed detection of magnetic levitation motors mainly include Hall effect switch detection, photoelectric encoder speed detection, magnetoelectric speed sensors, and leakage flux speed measurement.

[0003] One method, the Hall effect sensor, involves mounting a notched disk on the rotating part of the motor. A Hall sensor is fixed to the outside of the disk, directly opposite it. Each time the disk passes the Hall sensor, it outputs a pulse. The rotational speed is determined by counting the number of pulses. However, this method has drawbacks: it requires a separate disk to be mounted on the rotor, which is difficult to manufacture; it also increases the rotor's weight, affecting its dynamics; and it suffers from poor stability at high speeds.

[0004] The photoelectric encoder speed measurement method involves fixing a photoelectric encoder to the motor rotor shaft. The encoder has one or more light-transmitting gratings, each with a corresponding photosensitive element behind it. As the motor rotates, the encoder rotates as well. When a fixed light source shines on the encoder, the light passing through the gratings is received by the photosensitive element and generates a pulse signal. If the encoder's code number is 1, and the number of pulses measured within time t is N, then the rotational speed is n = 60N / (t*1). The disadvantage of this method is that while it offers high accuracy, it requires specific environmental conditions and a large installation space.

[0005] A magnetoelectric speed sensor consists of a magnet fixed to the rotating part of the motor, with a coil positioned at the outer edge of the circle along the magnet's trajectory. When the motor rotates, the coil generates induced pulse voltages. By counting these pulses over a certain period, the motor speed can be calculated. The disadvantages of this method are: its applicability is limited; magnetic levitation motors can reach speeds of 30,000-60,000 rpm, and this method suffers from low accuracy and poor stability.

[0006] The leakage magnetic field speed measurement method utilizes the frequency of the induced current generated by an asynchronous motor cutting magnetic lines of force in a rotating magnetic field. This frequency is the difference between the motor's rotor frequency and stator voltage frequency. By processing the leakage magnetic field of the induction motor, the stator voltage frequency signal and the difference frequency signal can be obtained. The synchronous speed of the motor can be obtained from the stator voltage frequency, and the speed difference signal can be obtained from the difference frequency signal. The difference between the two is the asynchronous speed of the motor. The disadvantage of this method is that it is only suitable for ferromagnetic materials and not for specimens with coatings or coverings. If the defect is far from the surface, the magnetic field distortion around the defect mainly occurs around the defect, and in this case, a leakage magnetic field may not appear on the workpiece surface. Summary of the Invention

[0007] To overcome the problems existing in related technologies, this disclosure provides a rotation speed detection device and a magnetic levitation shaft system.

[0008] The first aspect of this disclosure provides a speed detection device, which includes: a control board and a silicon steel sheet assembly, the silicon steel sheet assembly including a plurality of stacked silicon steel sheet groups; along the length direction of the silicon steel sheet assembly, the silicon steel sheet assembly includes a first end and a second end, and both the first end and the second end are provided with a first probe and a second probe;

[0009] The first probe and the second probe, located at the same end of the silicon steel sheet assembly, are arranged opposite to each other, and the distance between the first probe and the second probe is greater than or equal to the thickness of the silicon steel sheet assembly.

[0010] The first probe and the second probe are respectively wound with coils, and the coils are connected to the control board.

[0011] In some embodiments of this disclosure, the silicon steel sheet assembly includes a plurality of stacked silicon steel sheets, which are arc-shaped.

[0012] In some embodiments of this disclosure, the angle between the line connecting the first probe disposed at the first end and the second end and the center of the silicon steel sheet is 90 degrees.

[0013] In some embodiments of this disclosure, the silicon steel sheet assembly includes a first silicon steel sheet group, a second silicon steel sheet group, and a third silicon steel sheet group, wherein the second silicon steel sheet group is located between the first silicon steel sheet group and the third silicon steel sheet group, the first probe is disposed on the first silicon steel sheet group, and the second probe is disposed on the third silicon steel sheet group.

[0014] The second aspect of this disclosure proposes a magnetic levitation bearing system, which includes a rotor, a thrust disk, an axial magnetic bearing stator assembly, and a speed detection device as proposed in the first aspect of this disclosure. The thrust disk and the axial magnetic bearing stator assembly are respectively sleeved on the rotor. The two stator cores of the axial magnetic bearing stator assembly are symmetrically arranged about the thrust disk. The silicon steel sheet assembly is arranged on the side of one of the two stator cores closer to the thrust disk. The thrust disk includes a first radial direction, and notches are respectively provided at both ends of the thrust disk in the first radial direction. When the coil is energized, magnetic lines of force are generated between the first probe and the second probe arranged opposite to each other. During the rotation of the rotor, the notches cut the magnetic lines of force.

[0015] The control board is configured to determine the rotor speed based on the change in induced electromotive force generated by the notch cutting the magnetic lines of force.

[0016] In some embodiments of this disclosure, the cross-section of the notch is a plane; the thrust disk includes a second radial direction perpendicular to the first radial direction, and the cross-section of the notch is parallel to the second radial direction.

[0017] In some embodiments of this disclosure, a rounded transition is provided between the notch and the outer circle of the thrust disk.

[0018] In some embodiments of this disclosure, the first probe and the second probe, which are arranged opposite to each other, are symmetrical about the axis of symmetry of the two stator cores.

[0019] In some embodiments of this disclosure, a groove is provided on the side of the stator core near the thrust plate, and the silicon steel sheet assembly is disposed in the groove.

[0020] In some embodiments of this disclosure, the magnetic levitation bearing system includes a bearing housing, one of the two stator cores is disposed on the bearing housing, and the control board is disposed on the bearing housing.

[0021] The technical solutions provided by the embodiments of this disclosure can include the following beneficial effects: The speed detection device of this disclosure is a non-contact measurement device, which can work in environments such as smoke, water vapor, and oil vapor, has strong anti-interference ability, strong output signal, and wide measurement range. The speed detection device of this embodiment has low maintenance cost, does not require mechanical movement or lubrication, has a compact structure, and is easy to install. The speed detection device of this embodiment can make full use of the space between the thrust plate and the axial magnetic bearing stator core, avoiding problems such as rotor lengthening, insufficient rotor strength, and decreased motor rotation performance caused by separately setting up a mounting plate and machining notches on the rotor.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] Figure 1 is a schematic diagram of a silicon steel sheet assembly according to an exemplary embodiment.

[0025] Figure 2 is a cross-sectional view of a silicon steel sheet assembly according to an exemplary embodiment.

[0026] Figure 3 is a cross-sectional view of a magnetic bearing system according to an exemplary embodiment.

[0027] Figure 4 is a schematic diagram of a thrust disk according to an exemplary embodiment.

[0028] Figure 5 is an assembly diagram of a silicon steel sheet assembly and a stator core according to an exemplary embodiment.

[0029] Figure 6 is a cross-sectional view of the assembly of a silicon steel sheet assembly and a stator core according to an exemplary embodiment.

[0030] Wherein: 1-Rotor; 2-Stator core; 3-Thrust disc; 4-Control board; 5-Silicon steel sheet assembly; 6-Bearing housing; 31-Notch; 32-First radial direction; 33-Second radial direction; 51-First silicon steel sheet assembly; 52-Second silicon steel sheet assembly; 53-Third silicon steel sheet assembly; 54-First probe; 55-Second probe; 56-Coil; 21-Sink; Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0032] The technical solution of this embodiment will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the following implementation methods and embodiments can be combined with each other.

[0033] According to an exemplary embodiment of this disclosure, as shown in Figures 1 and 2, this embodiment proposes a rotational speed detection device. The rotational speed detection device includes a control board (not shown) and a silicon steel sheet assembly 5. The silicon steel sheet assembly 5 includes multiple stacked silicon steel sheet groups. The thickness of the multiple silicon steel sheet groups can be the same or different, and the thickness of the multiple silicon steel sheet groups can be flexibly set according to the processing difficulty and the performance of the rotational speed detection device. The multiple silicon steel sheet groups can be stacked and connected by means of snap-fit, bonding, connector connection or welding. In one example, the multiple silicon steel sheet groups are sequentially riveted and pressed together before welding. Along the length direction of the silicon steel sheet assembly 5, the silicon steel sheet assembly 5 includes a first end and a second end. Both the first end and the second end are provided with a first probe 54 and a second probe 55, and the first probe 54 and the second probe 55 are provided on two different silicon steel sheet groups. The first probe 54 and the second probe 55, located at the same end of the silicon steel sheet assembly 5, are positioned opposite each other, with the distance between them greater than or equal to the thickness of the silicon steel sheet assembly. This distance provides space for the coil 56, ensuring that the coil 56 is wound around both probes. The spacing between the first probe 54 and the second probe 55 also prevents interference between the silicon steel sheet assemblies containing the first probe 54 and the second probe 55. This arrangement of the first probe 54 and the second probe 55 improves the accuracy and stability of the detection, and enhances the anti-interference capability of the speed detection device. Coils 56 are wound on the first probe 54 and the second probe 55 respectively. The coils 56 wound on the first probe 54 and the second probe 55 are connected to the control board respectively. When the coils 56 are energized, magnetic lines of force are generated between the first probe 54 and the second probe 55 which are set opposite each other. The control board receives the change in inductance caused by the change in magnetic lines of force during the rotation of the motor rotor 1, and converts the received change in inductance into pulse signals. By counting the number of pulse signals per unit time, the motor speed is obtained by converting the number of pulse signals.

[0034] In some embodiments, the silicon steel sheet assembly includes multiple stacked silicon steel sheets. For example, each silicon steel sheet assembly is formed by stacking eight silicon steel sheets. As shown in FIG1, the silicon steel sheets are arc-shaped to match the motion trajectory of the rotor 1, avoiding interference of the silicon steel sheet assembly 5 with the rotor or thrust disk and improving the accuracy of speed detection.

[0035] In some embodiments, the angle between the first probe 54 located at the first end and the center of the silicon steel sheet and the line connecting them is 90 degrees. When the angle is less than 90 degrees, the magnetic lines of force at the first end and the second end interfere with each other, affecting the accuracy of the detection results. When the angle is greater than 90 degrees, it increases the volume of the silicon steel sheet assembly 5, increases its space occupation within the motor, and increases the amount of consumables. Therefore, this embodiment sets the angle between the first probe 54 located at the first end and the center of the silicon steel sheet and the line connecting them to 90 degrees, thereby reducing the space occupied by the silicon steel sheet assembly 5 and saving consumables while ensuring that the magnetic lines of force at the first end and the second end do not interfere with each other.

[0036] In this embodiment, the silicon steel sheet assembly 5 has three or more silicon steel sheet groups. In one example, as shown in Figure 2, the silicon steel sheet assembly 5 includes a first silicon steel sheet group 51, a second silicon steel sheet group 52, and a third silicon steel sheet group 53. The second silicon steel sheet group 52 is located between the first silicon steel sheet group 51 and the third silicon steel sheet group 53. The first probe 54 is disposed on the first silicon steel sheet group 51, and the second probe 55 is disposed on the third silicon steel sheet group 53. This allows the silicon steel sheet assembly 5 to meet the requirements of rotational speed detection with a minimum volume, while reducing the space occupied by the silicon steel sheet assembly 5 and lowering the production cost of the silicon steel sheet assembly 5.

[0037] The speed detection device in this embodiment is a non-contact measurement device that can work in environments such as smoke, water vapor, and oil vapor. It has strong anti-interference ability, strong output signal, and wide measurement range. At the same time, it has low maintenance cost, the operation of the inductive speed sensor does not require mechanical movement, no lubrication is required, the structure is compact, and it is easy to install.

[0038] According to an exemplary embodiment of this disclosure, as shown in Figures 3-6, this embodiment proposes a magnetic levitation bearing system. The magnetic levitation bearing system includes a rotor 1, a thrust disk 3, an axial magnetic bearing stator assembly, and the speed detection device proposed in the above embodiment. The thrust disk 3 and the axial magnetic bearing stator assembly are respectively sleeved on the rotor 1. The two stator cores 2 of the axial magnetic bearing stator assembly are symmetrically arranged about the thrust disk 3. The silicon steel sheet assembly 5 is arranged on the side of either of the two stator cores 2 closest to the thrust disk 3. The thrust disk 3 includes a first radial direction 32. Notches 31 are respectively provided at both ends of the thrust disk 3 in the first radial direction 32. When the coil 56 is energized, magnetic lines of force are generated between the oppositely arranged first probe 54 and second probe 55. During the rotation of the rotor 1, the notches 31 cut the magnetic lines of force. The control board 4 is configured to determine the speed of the rotor 1 based on the change in the induced electromotive force generated by the notches 31 cutting the magnetic lines of force. In one example, the control board 4 receives the change in induced electromotive force when the rotor 1 rotates and converts it into a pulse signal. By counting the number of pulse signals per unit time, the rotational speed of the rotor 1 is obtained.

[0039] This embodiment utilizes the space between the thrust plate 3 and the two stator cores 2 to set up a speed detection device, so as to make reasonable use of the internal space of the magnetic levitation bearing system. At the same time, by using the notch 31 set on the thrust plate 3 to cut the magnetic lines of force, it avoids the problems of insufficient strength of the rotor 1 and reduced motor rotation performance caused by separately setting up a mounting plate and machining notches on the rotor 1, which would increase the length of the rotor 1.

[0040] In some embodiments, the cut surface of the notch 31 is planar, and the thrust disk 3 includes a second radial direction 33 perpendicular to the first radial direction 32. The cut surface of the notch 31 is parallel to the second radial direction 33, so that the changes in the induced electromotive force generated by the notches 31 at both ends of the first radial direction 32 of the thrust disk 3 are consistent, ensuring the accuracy of the detection results. The size of the notch 31 is not limited. In one example, the notch 31 is a section cut off from each end of the first radial direction 32 of the thrust disk 3. The cut-off portions are symmetrical vertically, and the cut-off portions are 4 mm away from the outer circle of the thrust disk 3. When the cut-off portions are 4 mm away from the outer circle of the thrust disk 3, the change in magnetic reluctance caused by the rotation of the thrust disk 3 is most obvious.

[0041] In some embodiments, as shown in FIG4, a rounded transition is provided between the notch 31 and the outer circle of the thrust disk 3 to avoid a sharp transition between the thrust disk 3 and the notch 31, which would cause drastic changes in the magnetic field lines when the notch 31 cuts the magnetic field lines, thus affecting the accuracy of the detection results.

[0042] In some embodiments, as shown in FIG3, the first probe 54 and the second probe 55 are symmetrical about the axis of symmetry of the two stator cores 2, so that the notch 31 of the thrust disk 3 uniformly cuts the magnetic lines of force between the first probe 54 and the second probe 55, thereby improving the accuracy of rotational speed detection.

[0043] In some embodiments, as shown in FIG5, a groove 21 is provided on the side of the stator core 2 near the thrust plate 3, and the silicon steel sheet assembly 5 is disposed in the groove 21. The size of the groove 21 is adapted to the size of the silicon steel sheet assembly 5 to reduce the space occupied by the silicon steel sheet assembly 5. Under the premise of ensuring speed detection, the length of the rotor 1 is not increased, thus ensuring the strength of the rotor 1 and the rotational performance of the motor. The silicon steel sheet assembly 5 can be disposed on the stator core 2 by means of snap-fit, plug-in, or connector. In one example, as shown in FIG5 and FIG6, the silicon steel sheet assembly 5 is fixed in the groove 21 of the stator core 2 by fixing bolts, and the inner circle dimension of the silicon steel sheet assembly 5 is 2mm larger than the outer circle dimension of the thrust plate 3.

[0044] In some embodiments, as shown in FIG3, the magnetic levitation bearing system includes a bearing housing 6, one of the two stator cores 2 is disposed on the bearing housing 6, and a control plate 4 is disposed on the bearing housing 6 to fix the control plate 4 and make reasonable use of the internal space of the magnetic bearing system.

[0045] The rotational speed detection principle of the magnetic levitation bearing system in this embodiment is as follows: When the coils 56 on the first probe 54 and the second probe 55 of the silicon steel sheet assembly 5 of the rotational speed detection device are energized, magnetic lines of force are generated between the relatively positioned first probe 54 and second probe 55. When the rotor 1 rotates, it drives the thrust disk 3 to rotate. Because the thrust disk 3 has a notch 31, the relative position of the notch 31 on the outer circle of the thrust disk 3 changes alternately during the rotation of the thrust disk 3. When the distance between the thrust disk 3 and the first probe 54 or the second probe 55 of the silicon steel sheet assembly 5 is the smallest, the magnetic resistance is the smallest and the magnetic flux is the largest. When the distance between the thrust disk 3 and the first probe 54 or the second probe 55 of the silicon steel sheet assembly 5 is the largest, the magnetic resistance is also the largest and the magnetic flux is the smallest. As the thrust disk 3 rotates, the magnetic resistance changes periodically, and the working magnetic flux of the speed detection device also changes periodically. The induced electromotive force between the first probe 54 and the second probe 55 changes periodically, thereby inducing a periodically changing electrical signal in the coil 56. The control board 4 converts the periodically changing electrical signal into a pulse signal, and the rotor speed is obtained by calculation.

[0046] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0047] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A magnetic levitation bearing system, characterized in that, The magnetic levitation bearing system includes a speed detection device, which includes a control board (4) and a silicon steel sheet assembly (5). The silicon steel sheet assembly (5) includes multiple stacked silicon steel sheet groups. Along the length of the silicon steel sheet assembly (5), the silicon steel sheet assembly (5) includes a first end and a second end, and both the first end and the second end are provided with a first probe (54) and a second probe (55). The first probe (54) and the second probe (55) located at the same end of the silicon steel sheet assembly (5) are arranged opposite to each other, and the interval between the first probe (54) and the second probe (55) is greater than or equal to the thickness of the silicon steel sheet group. A coil (56) is wound on the first probe (54) and the second probe (55), and the coil (56) is connected to the control board (4). The magnetic levitation bearing system also includes a rotor (1), a thrust disk (3), and an axial magnetic bearing stator assembly. The thrust disk (3) and the axial magnetic bearing stator assembly are respectively sleeved on the rotor (1). The two stator cores (2) of the axial magnetic bearing stator assembly are symmetrically arranged about the thrust disk (3). The silicon steel sheet assembly (5) is arranged on the side of one of the two stator cores (2) closer to the thrust disk (3). The thrust disk (3) includes a first radial direction (32). The thrust disk (3) is provided with notches (31) at both ends of the first radial direction (32). When the coil (56) is energized, magnetic lines of force are generated between the first probe (54) and the second probe (55) arranged opposite to each other. During the rotation of the rotor (1), the notches (31) cut the magnetic lines of force. The control board (4) is configured to determine the rotational speed of the rotor (1) based on the change of the induced electromotive force generated by the notches (31) cutting the magnetic lines of force.

2. The magnetic levitation bearing system according to claim 1, characterized in that, The silicon steel sheet assembly comprises multiple stacked silicon steel sheets, which are arc-shaped.

3. A magnetic levitation bearing system according to claim 2, characterized in that, The angle between the line connecting the first probe (54) located at the first end and the second end and the center of the silicon steel sheet is 90 degrees.

4. A magnetic levitation bearing system according to claim 1, characterized in that, The silicon steel sheet assembly (5) includes a first silicon steel sheet group (51), a second silicon steel sheet group (52) and a third silicon steel sheet group (53). The second silicon steel sheet group (52) is located between the first silicon steel sheet group (51) and the third silicon steel sheet group (53). The first probe (54) is disposed on the first silicon steel sheet group (51) and the second probe (55) is disposed on the third silicon steel sheet group (53).

5. A magnetic levitation bearing system according to claim 1, characterized in that, The cut surface of the notch (31) is a plane; the thrust disk (3) includes a second radial direction (33) perpendicular to the first radial direction (32), and the cut surface of the notch (31) is parallel to the second radial direction (33).

6. A magnetic levitation bearing system according to claim 1, characterized in that, A rounded transition is provided between the notch (31) and the outer circle of the thrust disk (3).

7. A magnetic levitation bearing system according to claim 5, characterized in that, The first probe (54) and the second probe (55) are symmetrical about the axis of symmetry of the two stator cores (2).

8. A magnetic levitation bearing system according to claim 1, characterized in that, A groove (21) is provided on the side of the stator core (2) near the thrust plate (3), and the silicon steel sheet assembly (5) is disposed in the groove (21).

9. A magnetic levitation bearing system according to claim 1, characterized in that, The magnetic levitation bearing system includes a bearing housing (6), one of the two stator cores (2) is disposed on the bearing housing (6); the control board (4) is disposed on the bearing housing (6).

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