Inductive displacement sensor of magnetic suspension bearing and magnetic suspension bearing

Abstract

The invention provides an inductance type displacement sensor of a magnetic suspension bearing and the magnetic suspension bearing, the inductance type displacement sensor of the magnetic suspension bearing comprises a rotating shaft, a first probe and a second probe, the first probe and the second probe are both located on the periphery of the rotating shaft, the rotating shaft has an axis direction, and the first probe and the second probe are arranged in the axis direction. The first probe is located at a first axial position, the second probe is located at a second axial position, and the second axial position and the first axial position are spaced or connected in the axis direction; the first probe can detect the axial displacement and the radial displacement of the rotating shaft, and the second probe can detect the radial displacement of the rotating shaft so as to compare and compensate the radial displacement, detected by the first probe, of the rotating shaft. According to the invention, the interference of axial displacement on the radial detection of the first probe (wedge-shaped probe) can be reduced, the detection error is reduced, and the precision of axial and radial displacement detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic levitation bearings, and particularly relates to an inductive displacement sensor and a magnetic levitation bearing for a magnetic levitation bearing. Background Art

[0002] When a magnetic levitation bearing is working, the rotating shaft is levitated in the air by electromagnetic force, so that mechanical contact between the rotating shaft and the stator of the magnetic bearing is avoided. Compared with mechanical bearings, it has the advantages of no mechanical wear, no need for lubrication, long service life, high rotational speed and strong reliability. Therefore, it is widely used in high-speed rotating industrial manufacturing fields such as flywheel energy storage, molecular pumps, compressors, aerospace, etc. In order for the rotating shaft to rotate continuously and stably during operation, a displacement sensor needs to be used to monitor the axial center trajectory of the rotating shaft. At present, the non-contact displacement sensors widely used in the field of magnetic levitation bearing systems mainly include eddy current displacement sensors, capacitive displacement sensors and inductive displacement sensors. Among them, the eddy current displacement sensor needs to use a high-frequency alternating current signal above 400 kHz, has weak anti-electromagnetic interference ability and is greatly affected by temperature, so the detection accuracy is relatively low. The capacitive displacement sensor monitors the displacement change of the rotating shaft by detecting the change of the capacitance value between the surface of the rotating shaft and the probe. The detection accuracy is easily affected by media such as dust and oil in the air, and is not suitable for industrial sites with complex working conditions.

[0003] The inductive displacement sensor detects the displacement change of the rotating shaft by changing the inductance of the probe coil due to the change of the magnetic conduction area corresponding to the coil probe and the rotating shaft. Therefore, the sensitivity and detection accuracy of the inductive displacement sensor depend on the detection surface area in the sensor probe and the gap between the probe and the rotating shaft. For existing inductive displacement sensors, both radial displacement detection and axial displacement detection adopt an independent installation structure, which requires a large installation space, and the detection surface area of the sensor probe is small. When the displacement of the rotating shaft changes, the inductance change of the sensor probe coil is small, so the sensitivity and detection accuracy of the sensor are relatively low.

[0004] After a patent search, the patents and documents related to the present invention are as follows:

[0005] In the sensor of the patent with the patent number CN212717638U, namely "A High-Sensitivity Inductive Radial and Axial Displacement Sensor in a Magnetic Levitation Bearing", the sensor stator laminations are arranged outside the sensor rotor laminations. The stator probe is wedge-shaped, and the corresponding rotor part becomes an inclined plane with the same inclination angle. The rotor inclined plane part is made of a magnetic conductive material. When there is an axial relative movement between the stator and the rotor, the area of the magnetic conductive material of the rotor corresponding to the wedge-shaped probe of the sensor and the air gap between the stator and the rotor change, thereby monitoring the displacement trajectory of the rotating shaft. In this patent, the axial displacement and radial displacement of the rotor are detected by the changes in the area of the magnetic conductive material corresponding to the left and right wedge-shaped probes of the stator and the air gap changes. However, since the inductive displacement sensor of this patent detects through the change in the area of the magnetic conductive material of the wedge-shaped probe, there is interference between each detection channel. When calculating the displacement change in the radial direction, the calculation error is large and it is easily interfered. Moreover, the area of the magnetic conductive material corresponding to the probe in the radial direction of the rotor is small, resulting in low sensitivity in the radial direction.

[0006] In the patent with the patent number CN117249164A, namely "An Axial and Radial Self-Inductive Displacement Sensor for a Magnetic Levitation Bearing System", the stator core of the sensor is a circular ring core with magnetic poles on the inner ring. The coil is wound around the magnetic pole probe, and the magnetic pole probe is aligned with the rotor step surface. The axial and radial displacements of the rotor are detected by changing the effective magnetic pole area of the magnetic pole probe. Since in the sensor structure proposed in this patent, it can only detect the axial and radial displacements of the rotor through a single magnetic pole probe, when detecting the displacement change of the rotor, the calculation error will be relatively large, and the magnetic conductive area is relatively small, and the change in the inductance of the probe is small, resulting in low sensitivity of the sensor.

[0007] Due to the technical problems that the inductive displacement sensor of the magnetic levitation bearing in the prior art has interference caused by axial / radial displacement to the radial / axial detection of the probe, resulting in low detection accuracy, etc., the present invention researches and designs an inductive displacement sensor for a magnetic levitation bearing and a magnetic levitation bearing. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the inductive displacement sensor of the magnetic levitation bearing in the prior art has interference caused by axial / radial displacement to the radial / axial detection of the probe, resulting in low detection accuracy, so as to provide an inductive displacement sensor for a magnetic levitation bearing and a magnetic levitation bearing.

[0009] To solve the above problems, the present invention provides an inductive displacement sensor for a magnetic levitation bearing, which includes:

[0010] A rotating shaft, a first probe, and a second probe. The first probe and the second probe are both located on the outer periphery of the rotating shaft. The rotating shaft has an axial direction. The first probe is located at a first axial position, and the second probe is located at a second axial position. Along the axial direction, the second axial position is spaced apart from or adjacent to the first axial position.

[0011] The first probe can detect the axial displacement and radial displacement of the rotating shaft, and the second probe can detect the radial displacement of the rotating shaft to compare and compensate for the radial displacement of the rotating shaft detected by the first probe.

[0012] In some embodiments,

[0013] The surface of the first probe facing the rotating shaft is the first surface. In a vertical cross-sectional plane passing through the axis of the rotating shaft, the first surface is not parallel to the axis of the rotating shaft. The outer peripheral surface of the rotating shaft has a second surface, and the second surface is also not parallel to the axis of the rotating shaft. Moreover, the first surface and the second surface are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft through the change in the distance between the first surface and the second surface during the axial and / or radial movement of the rotating shaft.

[0014] The surface of the second probe facing the rotating shaft is the third surface. In a vertical cross-sectional plane passing through the axis of the rotating shaft, the third surface is parallel to the axis of the rotating shaft. The outer peripheral surface of the rotating shaft has a fourth surface, and the fourth surface is also parallel to the axis of the rotating shaft. Moreover, the third surface and the fourth surface are opposite and parallel, and can detect the radial displacement of the rotating shaft through the change in the distance between the third surface and the fourth surface during the radial movement of the rotating shaft.

[0015] In some embodiments,

[0016] In a vertical cross-sectional plane passing through the axis of the rotating shaft, the outer normal of the second surface extends away from the axis of the rotating shaft and also extends away from the fourth surface. The outer normal of the fourth surface is perpendicular to the axis of the rotating shaft, and the outer normal of the second surface does not intersect the outer normal of the fourth surface.

[0017] The second surface and the fourth surface are adjacent along the axial direction of the rotating shaft, and a convex portion protruding radially outward with respect to the outer peripheral surface of the rotating shaft is formed at the second surface and the fourth surface.

[0018] In some embodiments,

[0019] In a vertical cross-sectional plane passing through the axis of the rotating shaft, the second surface is an inclined surface. One end of the second surface is connected to the outer peripheral surface of the rotating shaft, and the other end gradually extends radially outward to connect with one end of the fourth surface. The other end of the fourth surface is higher than the outer peripheral surface of the rotating shaft and forms a step with the outer peripheral surface of the rotating shaft, such that the outer diameter dimension of the outer periphery in the radial direction of the fourth surface is the largest part on the rotating shaft.

[0020] In some embodiments,

[0021] In a vertical cross-sectional plane passing through the axis of the rotating shaft, the first probe is located on one side of the axis of the rotating shaft, and the second probe is located on the other side of the axis of the rotating shaft.

[0022] In some embodiments,

[0023] Two first probes are adjacent and spaced along the circumferential direction of the rotating shaft to form a first probe unit. Two adjacent second probes along the circumferential direction of the rotating shaft form a second probe unit. Both the first probe unit and the second probe unit are multiple, and the first probe unit and the second probe unit are staggered and spaced along the circumferential direction.

[0024] In some embodiments,

[0025] In the first probe unit, a first probe coil is wound around one of the adjacent first probes, and a second probe coil is wound around the other first probe, and the first probe coil is connected and conducted with the second probe coil; in the second probe unit, a third probe coil is wound around one of the adjacent second probes, and a fourth probe coil is wound around the other second probe, and the third probe coil is connected and conducted with the fourth probe coil.

[0026] In some embodiments,

[0027] It includes a first-layer stator silicon steel sheet and a second-layer stator silicon steel sheet. Both the first-layer stator silicon steel sheet and the second-layer stator silicon steel sheet are of annular structures, and they are arranged in a fitting manner along the axial direction of the rotating shaft. The first probe is protrudingly arranged radially inward on the inner peripheral wall of the first-layer stator silicon steel sheet, and the second probe is protrudingly arranged radially inward on the inner peripheral wall of the second-layer stator silicon steel sheet.

[0028] In some embodiments,

[0029] The rotating shaft includes a shaft section with an integral magnetic conduction structure, that is, a rotating shaft magnetic conductor. The rotating shaft magnetic conductor extends from the shaft section opposite to the first probe through the shaft section opposite to the second probe, such that both the first probe and the second probe are opposite to the rotating shaft magnetic conductor.

[0030] In some embodiments,

[0031] When the rotating shaft does not shift, the initial inductances of two circumferentially adjacent first probes are L 01 and L 02 , the input voltage is U s , then:

[0032]

[0033] where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of the probe, μ0 is the magnetic permeability, and δ1, δ2 represent the air gaps formed from the initial air gap δ0 after the rotor undergoes displacement changes;

[0034] When the rotating shaft axially displaces and surges by Δδ in the direction of the first probe, the magnetic conduction surfaces A1 and A2 of the two first probes both increase, and the air gaps δ1 and δ2 between the two first probes and the rotating shaft both decrease. δ1 = δ2 = (δ0 - Δδ). The self - inductance change amounts of the two first - probe coils are respectively:

[0035]

[0036] ΔL2 = ΔL1;

[0037] Therefore, the axial output voltage is:

[0038] In some embodiments,

[0039] When the rotating shaft does not have a radial offset and is at the center of rotation, the initial gaps between multiple second probes and the rotating shaft are all δ′0, their coil turns are all W2, the magnetic conduction area is A′0, and the initial inductances of the two second probes located above are L 06 and L 07 , and the initial inductances of the two second probes located below are L 08 and L 09 , the input voltage is U s , then:

[0040]

[0041] When the rotating shaft undergoes a radial displacement and surges downward by Δδ′, the air gap δ′1 between the two third probes located below and the rotating shaft decreases, the inductances L5 and L6 increase, the air gap δ′2 between the two second probes located above and the rotating shaft increases, and the inductances L3 and L4 decrease. At this time:

[0042]

[0043] Therefore, the radial output voltages of the multiple second probes in the second layer are as follows:

[0044] And assume that at this time, one of the magnetic conduction surfaces of the first probe is A′2, the gap is δ″2, the other magnetic conduction surface of the first probe is A′1, the gap is δ″1, A′1 = A′2, and δ″1 = δ″2;

[0045] At this time, the radial output voltage in the first probe of the first-layer stator is:

[0046] Finally, the radial output voltage U of the second-layer stator j0 and the radial output voltage U′ in the upper-layer wedge probe z0 , after normalization, the final radial detection output voltage of the sensor is:

[0047] U′0 = k * U j0 +(1 - k) * U′ z0 , where k is a constant.

[0048] The present invention also provides a magnetic suspension bearing, which includes the inductive displacement sensor of the aforementioned magnetic suspension bearing.

[0049] The inductive displacement sensor and the magnetic suspension bearing of the magnetic suspension bearing provided by the present invention have the following beneficial effects:

[0050] 1. By using the first probe capable of detecting the axial displacement and radial displacement of the rotating shaft, the present invention can detect the axial and radial displacements. Further, by using the second probe capable of detecting the radial displacement of the rotating shaft, the radial displacement of the rotating shaft can be detected, so as to compare and compensate the radial displacement of the rotating shaft detected by the first probe, reduce the interference of the axial displacement on the radial detection of the first probe (wedge probe), improve the detection accuracy. Through the effective combination structure of the above-mentioned one probe for detecting the axial / radial displacement and one probe for detecting the radial displacement, the interference can be further reduced, the detection error can be reduced, and the detection accuracy of the axial and radial displacements can be improved.

[0051] 2. The high-sensitivity radial and axial integrated inductive displacement sensor for magnetic levitation bearings proposed by the present invention divides the entire stator of the sensor into upper and lower parts along the central axis. The upper half of the stator is provided with wedge-shaped coil probes evenly distributed circumferentially for detecting the axial and radial displacements of the rotor, and the lower half of the stator is provided with sensor probes evenly distributed circumferentially for detecting the radial displacement of the rotor. That is, when the rotor moves axially, the relative magnetic permeability area and gap between the wedge-shaped probes on the upper half of the stator and the rotating shaft change, increasing the inductance change of the axial probe coil and enhancing the sensitivity of the sensor. When the rotor deviates radially, both the wedge-shaped probes on the upper half of the stator and the radial probes on the lower half of the stator can detect the radial displacement deviation of the rotor, reducing the calculation error of detecting the radial displacement, effectively eliminating the interference between each sensor probe, improving the detection accuracy of the sensor, realizing the integration of radial and axial displacement detection of the rotating shaft, and saving the installation space of the sensor.

[0052] 3. The present invention also passes through a shaft section of the rotating shaft including an integral magnetic conduction structure, that is, a rotating shaft magnetic conductor. The rotating shaft magnetic conductor extends from the shaft section opposite to the first probe through the shaft section opposite to the second probe, so that both the first probe and the second probe are opposite to the rotating shaft magnetic conductor, which can further increase the magnetic conduction area and further improve the detection accuracy and detection performance. The present invention further passes through the second surface and the fourth surface being sequentially connected along the axis direction of the rotating shaft, and a protruding portion protruding radially outward relative to the outer peripheral surface of the rotating shaft is formed at the second surface and the fourth surface, which can further increase the magnetic conduction area of the magnetic conduction portion and further improve the detection accuracy and detection performance. Brief Description of the Drawings

[0053] Figure 1 is a three-dimensional structure diagram of the high-sensitivity radial and axial integrated inductive displacement sensor for magnetic levitation bearings of the present invention;

[0054] Figure 2 is a working schematic diagram of the high-sensitivity radial and axial integrated inductive displacement sensor for magnetic levitation bearings of the present invention;

[0055] Figure 3 is a working schematic diagram of the inductive sensor of the magnetic levitation bearing of the present invention when the rotor axially deviates;

[0056] Figure 4 is a working schematic diagram of the inductive sensor of the magnetic levitation bearing of the present invention when the rotor radially deviates.

[0057] The reference numerals are shown as:

[0058] 1. First probe coil; 2. First probe; 3. Rotating shaft magnetic conductor; 4. Rotating shaft; 5. Third probe coil; 6. Second probe; 7. Second probe coil; 8. Fourth probe coil; 9. First layer of stator silicon steel sheet; 10. Second layer of stator silicon steel sheet; A. First side; B. Second side; C. Third side; D. Fourth side. Detailed implementation manners

[0059] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually illustrative only and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0060] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0062] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary statements, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0063] For the sake of convenience in description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above-mentioned", etc. can be used here to describe the spatial positional relationship between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0064] In addition, it should be noted that using words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without additional statements, the above words have no special meanings. Therefore, it should not be construed as a limitation on the protection scope of the present invention.

[0065] As Figures 1-4 shown, the present invention provides an inductive displacement sensor for a magnetic levitation bearing, which includes:

[0066] A rotating shaft 4, a first probe 2 and a second probe 6. Both the first probe 2 and the second probe 6 are located on the outer periphery of the rotating shaft 4. The rotating shaft 4 has an axial direction. The first probe 2 is located at a first axial position, and the second probe 6 is located at a second axial position. Along the axial direction, the second axial position is spaced apart from or in contact with the first axial position.

[0067] The first probe 2 can detect the axial displacement and radial displacement of the rotating shaft 4, and the second probe 6 can detect the radial displacement of the rotating shaft 4 to compare and compensate for the radial displacement of the rotating shaft 4 detected by the first probe 2.

[0068] The present invention uses a first probe capable of detecting the axial displacement and radial displacement of a rotating shaft to detect axial and radial displacements. Further, a second probe capable of detecting the radial displacement of the rotating shaft is used to detect the radial displacement of the rotating shaft, so as to compare and compensate for the radial displacement of the rotating shaft detected by the first probe, reduce the interference of axial displacement on the radial detection of the first probe (wedge probe), improve the detection accuracy. Through the effective combination structure of one probe for detecting axial / radial displacement and one probe for detecting radial displacement, the interference can be further reduced, the detection error can be minimized, and the detection accuracy of axial and radial displacements can be improved.

[0069] The high-sensitivity radial and axial integrated inductive displacement sensor structure of the magnetic levitation bearing of the present invention is as Figure 1 shown. This structure designs the conventional integral stator structure into two stator modules (the first-layer stator silicon steel sheet 9 and the second-layer stator silicon steel sheet 10) of the upper and lower parts. The stator pole columns in the upper half are designed as wedge-shaped pole columns (the first probe 2), increasing the magnetic conduction area between the probe and the rotor. The shape of the magnetic conduction body 3 of the rotating shaft of this sensor is as follows: there is a horizontal plane in the middle that cooperates with the middle stator probe (the second probe 6) of the sensor. The left end of the horizontal plane is designed as a convex ramp surface parallel to the magnetic conduction surface of the upper half wedge-shaped stator probe (the first probe 2), and the overall material of the rotating shaft 4 needs to be a magnetic conduction material. On these two parts of the stator modules, various sensor probe coils (the first probe coil 1, the third probe coil 5, etc.) are evenly distributed along the stator circumference. And the central axes of the sensor probes on each stator module intersect at 90 degrees, so as to ensure that the crosstalk displacement of the rotating shaft 4 can be accurately detected in the mutually orthogonal radial directions. It should be particularly noted that during the entire assembly process of the sensor, it is necessary to ensure that the inclined surface of the wedge-shaped pole column always remains relatively parallel to the inclined surface of the rotor.

[0070] Figure 2 The figure shows a cross-sectional view of the high-sensitivity radial and axial integrated inductive displacement sensor of the magnetic levitation bearing working on the rotating shaft, and the structure is as shown in the figure. The working principle of the inductive displacement sensor is that when the displacement of the rotating shaft 4 changes, the impedance of the sensor probe coils (the first probe coil 1, the third probe coil 5, etc.) will change accordingly, so as to obtain the crosstalk displacement generated by the rotating shaft 4 according to the impedance change of the probe coils (the first probe coil 1, the third probe coil 5, etc.). The impedance change of the probe coils (the first probe coil 1, the third probe coil 5, etc.) is related to the size of the magnetic conduction surface of the rotating shaft 4 and the gap between the two. Therefore, the sensitivity and detection accuracy of the inductive displacement sensor depend on the detection surface area in the sensor probe and the gap between the probe and the rotating shaft.

[0071] In some embodiments,

[0072] The surface of the first probe 2 facing the rotating shaft 4 is the first surface A. In the vertical cross-sectional plane passing through the axis of the rotating shaft 4, the first surface A is not parallel to the axis of the rotating shaft 4. The outer peripheral surface of the rotating shaft 4 has a second surface B, and the second surface B is also not parallel to the axis of the rotating shaft 4. Moreover, the first surface A and the second surface B are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft 4 through the change in the distance between the first surface A and the second surface B during the axial and / or radial movement of the rotating shaft 4;

[0073] The surface of the second probe 6 facing the rotating shaft 4 is the third surface C. In the vertical cross-sectional plane passing through the axis of the rotating shaft 4, the third surface C is parallel to the axis of the rotating shaft 4. The outer peripheral surface of the rotating shaft 4 has a fourth surface D, and the fourth surface D is also parallel to the axis of the rotating shaft 4. Moreover, the third surface C and the fourth surface D are opposite and parallel, and can detect the radial displacement of the rotating shaft 4 through the change in the distance between the third surface C and the fourth surface D during the radial movement of the rotating shaft 4.

[0074] This is a further preferred structural form of the inductive displacement sensor of the magnetic levitation bearing of the present invention, that is, the first probe and the rotating shaft are arranged as the first surface and the second surface that are parallel to each other and inclined to the axis of the rotating shaft. Thus, when the rotating shaft undergoes axial movement or radial movement, the axial and radial displacement values of the rotating shaft can be obtained through the inductance change generated by the distance between the first and second surfaces inclined to the axis of the rotating shaft; however, there is still a situation where the conversion of the radial displacement through the radial inductance of the first probe is interfered by the axial displacement, and the accuracy is not high enough; at this time, the present invention combines the second probe with the third and fourth parallel surfaces on the rotating shaft, and these two surfaces are parallel to the axis of the rotating shaft, so as to be able to detect the inductance value generated by the radial displacement of the rotating shaft, and then compare and convert it with the radial displacement inductance values detected by the first and second probes, so as to obtain accurate radial and axial displacement values of the rotating shaft and effectively improve the detection accuracy of the displacement sensor.

[0075] For the inductive displacement sensor proposed by the present invention, the entire stator is divided into upper and lower parts along the central axis. The upper stator part is circumferentially distributed with coil probes having magnetically conductive surfaces with a certain slope for detecting the axial and radial displacements of the rotating shaft. The lower stator part is circumferentially distributed with coil probes for detecting the radial displacement of the rotating shaft, realizing an integrated design of the radial displacement detection and axial displacement detection of the magnetic levitation bearing, saving the installation space of the sensor, and at the same time eliminating the interference between each detection channel, and can effectively improve the detection accuracy and sensitivity of the sensor.

[0076] 1. The present invention provides a high-sensitivity integrated inductive displacement sensor for magnetic levitation bearings. The sensor stator is divided into upper and lower parts. Wedge-shaped probes for detecting the axial and radial displacements of the rotor are evenly distributed circumferentially on the upper part of the stator, and the sensor probes evenly distributed circumferentially on the lower part of the stator are used to detect the radial displacement of the rotor, improving the sensitivity of the sensor in the radial direction, realizing the integration of the detection of the radial and axial displacements of the rotating shaft, saving the installation space of the sensor, eliminating the interference between the individual sensor probes, and improving the detection accuracy of the sensor.

[0077] 2. In the present invention, the shape of the upper part of the stator coil probe of the sensor is designed as a wedge shape at a certain angle, increasing the magnetic conduction area between the probe and the rotor. That is, when the rotor moves axially, the relative magnetic conduction area and gap between the two change, increasing the inductance change of the axial probe coil and enhancing the sensitivity of the sensor. The wedge-shaped probes on the upper part of the stator and the radial probes on the lower part of the stator can both detect the radial displacement deviation of the rotor, reducing the calculation error of detecting the radial displacement and enhancing the detection accuracy of the sensor.

[0078] In some embodiments,

[0079] In the vertical cross-sectional plane passing through the axis of the rotating shaft 4, the outer normal of the second surface B extends away from the axis of the rotating shaft 4 and also extends away from the fourth surface D. The outer normal of the fourth surface D is perpendicular to the axis, and the outer normal of the second surface B does not intersect with the outer normal of the fourth surface D;

[0080] The second surface B and the fourth surface D are connected along the axis direction of the rotating shaft 4, and a convex portion protruding radially outward relative to the outer circumference of the rotating shaft 4 is formed at the second surface B and the fourth surface D.

[0081] This is a further preferred setting form of the second and fourth surfaces on the rotating shaft of the present invention, enabling the outer normals of the second surface and the fourth surface to extend in directions away from each other, which can cooperate with the first probe and the second probe to detect the displacement value of the rotating shaft moving in a specific axis direction, and also enabling the second surface and the fourth surface to form a structure that protrudes radially outward relative to the rotating shaft, thereby increasing the induction area and volume between this part and each probe respectively, and further improving the accuracy value of the probe for detecting the displacement of the rotating shaft. By arranging the second surface and the fourth surface on the rotating shaft to be connected in sequence, and the structure formed by the two being a convex portion protruding radially outward relative to the rotating shaft, the present invention can effectively increase the induction area and induction volume of the part that induces with multiple probes, thereby further improving the accuracy value of the probe for detecting the displacement of the rotating shaft.

[0082] In some embodiments,

[0083] In a vertical cross-sectional plane passing through the axis of the rotating shaft 4, the second surface B is an inclined surface. One end of the second surface B is connected to the outer peripheral surface of the rotating shaft 4, and the other end gradually extends radially outward to be connected to one end of the fourth surface D. The other end of the fourth surface D is higher than the outer peripheral surface of the rotating shaft 4 and forms a step with the outer peripheral surface of the rotating shaft 4, such that the outer diameter dimension of the radially outer periphery of the fourth surface D is the largest part on the rotating shaft 4.

[0084] In the present invention, through the inclined surface structure in which the second surfaces are inclined in opposite directions respectively, and the second surface is connected to the fourth surface, and the fourth surface is parallel to the axis, the part of the rotating shaft surrounded by the fourth surface is formed into the part with the largest outer diameter dimension on the rotating shaft, effectively increasing the induction area and induction volume of the part on the rotating shaft that inducts with multiple probes, thereby further improving the accuracy value of the probe for detecting the displacement of the rotating shaft.

[0085] Further preferably, the structure surrounded by the second surface is an annular frustum structure, and the structure surrounded by the fourth surface is also an annular cylindrical structure.

[0086] In some embodiments,

[0087] In a vertical cross-sectional plane passing through the axis of the rotating shaft 4, the first probe 2 is located on one side of the axis of the rotating shaft 4, and the second probe 6 is located on the other side of the axis of the rotating shaft 4.

[0088] This is a further preferred structural form of the present invention, that is, the first probe is located on one side of the axis in the vertical cross-section, and the second probe is located on the other side of the axis of the rotating shaft, so that it is not necessary to squeeze both probes on the same side, resulting in the extension of the magnetically conductive part of the rotating shaft. While ensuring that both probes can sense and detect, the structure can be made more compact and the volume can be reduced.

[0089] In some embodiments,

[0090] Two first probes 2 are adjacent and spaced along the circumferential direction of the rotating shaft 4 to form a first probe unit. Two adjacent second probes 6 along the circumferential direction of the rotating shaft 4 form a second probe unit. Both the first probe unit and the second probe unit are multiple, and the first probe unit and the second probe unit are staggered and spaced along the circumferential direction.

[0091] The present invention has two first probes in the circumferential direction to form a first probe unit, which can enhance the detection accuracy of the shaft diameter and axial displacement of the rotating shaft in the circumferential direction. Two or more second probes are arranged in the circumferential direction to form a second probe unit, so as to enhance the detection and verification accuracy of the radial displacement in the circumferential direction. The first probe unit and the second probe unit are staggered and arranged at intervals along the circumferential direction, which can improve the accuracy of the shaft and radial displacement detection at various positions of the rotating shaft in the circumferential direction and improve the accuracy of uniform detection.

[0092] In some embodiments,

[0093] In the first probe unit, a first probe coil 1 is wound around one of the adjacent first probes 2, and a second probe coil 7 is wound around the other first probe 2. The first probe coil 1 is connected and conducted with the second probe coil 7. In the second probe unit, a third probe coil 5 is wound around one of the adjacent second probes 6, and a fourth probe coil 8 is wound around the other second probe 6. The third probe coil 5 is connected and conducted with the fourth probe coil 8.

[0094] In the present invention, the coils wound around two adjacent first probes are connected and conducted, which can form a current-conducting structure, so as to detect their respective inductances and obtain the radial and axial displacement values of the rotating shaft. The second probe has two adjacent ones, and the third probe coil and the fourth probe coil respectively wound around the two adjacent second probes are connected and conducted, so as to form a conduction loop of the second probe, obtain the inductance, and obtain the radial displacement value of the rotating shaft, and compare and verify the radial displacement obtained by the first probe, so as to improve the detection accuracy of the shaft diameter and axial displacement of the rotating shaft.

[0095] In some embodiments,

[0096] It includes a first-layer stator silicon steel sheet 9 and a second-layer stator silicon steel sheet 10. Both the first-layer stator silicon steel sheet 9 and the second-layer stator silicon steel sheet 10 are of annular structures, and they are arranged in a fitting manner along the axial direction of the rotating shaft. The first probe 2 is protrudingly arranged on the inner peripheral wall of the first-layer stator silicon steel sheet 9 toward the radially inner side, and the second probe 6 is protrudingly arranged on the inner peripheral wall of the second-layer stator silicon steel sheet 10 toward the radially inner side.

[0097] The high-sensitivity radial and axial integrated inductive displacement sensor for a magnetic levitation bearing proposed by the present invention divides the entire stator of the sensor into upper and lower parts (the first and second layers of stator silicon steel sheets) along the central axis. Wedge-shaped coil probes evenly distributed circumferentially are provided on the upper half of the stator for detecting the axial and radial displacements of the rotor, and sensor probes evenly distributed circumferentially are provided on the lower half of the stator for detecting the radial displacement of the rotor. That is, when the rotor moves axially, the relative magnetic permeability area and gap between the wedge-shaped probes on the upper half of the stator and the rotating shaft change, increasing the inductance change of the axial probe coil and improving the sensitivity of the sensor. When the rotor deviates radially, both the wedge-shaped probes on the upper half of the stator and the radial probes on the lower half of the stator can detect the radial displacement deviation of the rotor, reducing the calculation error of detecting the radial displacement, effectively eliminating the interference between each sensor probe, improving the detection accuracy of the sensor, realizing the integration of the detection of the radial and axial displacements of the rotating shaft, and saving the installation space of the sensor.

[0098] In some embodiments,

[0099] The rotating shaft 4 includes a shaft section with an integral magnetic conduction structure, that is, the rotating shaft magnetic conductor 3. The rotating shaft magnetic conductor 3 extends from the shaft section opposite to the first probe 2 through the shaft section opposite to the second probe 6, so that both the first probe 2 and the second probe 6 are opposite to the rotating shaft magnetic conductor 3.

[0100] The present invention also includes a shaft section with an integral magnetic conduction structure in the rotating shaft, that is, the rotating shaft magnetic conductor. The rotating shaft magnetic conductor extends from the shaft section opposite to the first probe through the shaft section opposite to the second probe in sequence, so that both the first probe and the second probe are opposite to the rotating shaft magnetic conductor, which can further increase the magnetic conduction area and further improve the detection accuracy and detection performance.

[0101] In some embodiments,

[0102] When the rotating shaft 4 does not deviate, the initial inductances of two circumferentially adjacent first probes 2 are respectively L 01 and L 02 , the input voltage is U s , then:

[0103]

[0104] Where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of the probe, μ0 is the magnetic permeability, and δ1, δ2 represent the air gaps formed by the change of the initial air gap δ0 after the rotor undergoes displacement changes;

[0105] When the shaft 4 undergoes an axial displacement Δδ toward the first probe 2, the magnetic conductive surfaces A1 and A2 of the two first probes 2 become larger, and the air gaps δ1 and δ2 between the two first probes and the shaft are reduced, δ1 = δ2 = (δ0 - Δδ), and the changes in the self-inductance of the two first probe coils are respectively:

[0106]

[0107] ΔL2=ΔL1;

[0108] Therefore, the axial output voltage is:

[0109] This is the preferred method of detecting the axial displacement of the rotating shaft of the present invention, which can accurately obtain the displacement of the axial movement of the rotating shaft. Figure 3 The figure shows the working schematic diagram of the sensor when the rotor is axially offset. The initial gap between the wedge probe (first probe 2) and the rotating shaft 4 is δ0. The probe coils of the two are connected in series. The wedge probes (first probe 2, etc.) on the sensor are all W1, and the two corresponding wedge probes on the upper stator are wound into a differential structure. In the operation of the sensor proposed by the present invention, when the rotating shaft 4 is axially displaced to the left, the relative magnetic conductive area between the wedge probe (first probe 2) on the left sensor stator and the rotating shaft 4 becomes larger and the axial gap becomes smaller, which increases the inductance increase of the wedge probe coil (first probe coil 1), and then the wedge probe coil (first probe coil 1) opposite to the stator circumference is differentially connected, thereby greatly improving the axial detection sensitivity of the sensor.

[0110] In some embodiments,

[0111] When the shaft 4 is not radially offset and is at the center of rotation, the initial gaps between the multiple second probes 6 and the shaft 4 are all δ′0, the number of turns of the coils is all W2, the magnetic conductive area is A′0, and the initial inductances of the two second probes located at the top are L 06 and L 07 The initial inductances of the two second probes located below are L 08 and L 09 , the input voltage is U s ,but:

[0112]

[0113] When the shaft 4 moves radially downward by Δδ′, the air gap δ′1 between the two second probes at the bottom and the shaft decreases, the inductances L5 and L6 increase, the air gap δ′2 between the two second probes at the top and the shaft increases, and the inductances L3 and L4 decrease. At this time:

[0114]

[0115] Therefore, the radial output voltages of the multiple second probes 6 in the second layer are as follows:

[0116] And assume that at this time, the magnetic conduction surface of one of the first probes 2 is A'2, the gap is δ"2, the magnetic conduction surface of the other first probe 2 is A'1, the gap is δ″1, A'1 = A'2, δ″1 = δ″2;

[0117] At this time, the radial output voltage in the first probe of the first-layer stator is:

[0118] Finally, the radial output voltage U of the second-layer stator j0 and the radial output voltage U' in the upper-layer wedge probe z0 , after normalization, the final radial detection output voltage of the sensor is:

[0119] U'0 = k * U j0 +(1 - k) * U' z0 , where k is a constant.

[0120] This is the preferred method for detecting the axial displacement of the rotating shaft in the present invention, which can accurately obtain the displacement of the radial movement of the rotating shaft, Figure 4 The working schematic diagram of the sensor when the rotor is radially offset is shown. When the rotating shaft undergoes a radial offset downward, the radial gaps between the wedge probes (such as the first probe 2) in the lower part of the circumference and the radial probes (such as the second probe 6) below the lower-layer stator and the rotor all become smaller, while the radial gaps between the wedge probes in the upper part of the circumference and the radial probes above the lower-layer stator and the rotor all become smaller. Finally, the differential of the inductance change signals of the probe coils corresponding to the upper and lower parts of the circumference of each stator is performed, and thus the radial movement displacement of the rotating shaft 4 is obtained.

[0121] The wedge-shaped stator probe (such as the first probe 2) in the upper half of the sensor of the present invention can not only detect the axial displacement of the rotating shaft 4, but also detect the displacement deviation of the rotating shaft 4 in the radial direction, reducing the calculation error of detecting the radial displacement and improving the radial detection accuracy of the sensor.

[0122] The inductive displacement sensor proposed by the present invention can realize the integration of the detection of the radial and axial displacements of the rotating shaft, saving the installation space of the sensor, eliminating the interference between the probe coils of each sensor, improving the sensitivity and detection accuracy of the sensor in the radial and axial directions, and greatly improving the operation stability of the magnetic suspension bearing system.

[0123] The present invention also provides a magnetic suspension bearing, which includes the inductive displacement sensor of the magnetic suspension bearing described above.

[0124] The magnetic suspension bearing of the present invention has the following effects:

[0125] 1. The sensor stator of the present invention is divided into upper and lower parts, which are respectively used to detect the axial and radial displacements of the rotor, realizing the integration of the detection of the radial and axial displacements of the rotating shaft, saving the installation space of the sensor, eliminating the interference between the probe heads of each sensor, and improving the detection accuracy of the sensor.

[0126] 2. The axial probe of the sensor of the present invention is designed as a wedge with a certain angle, increasing the magnetic conduction area between the probe and the rotor, enhancing the relative magnetic conduction area and the change of the gap between the probe and the rotor, increasing the inductance change of the axial probe coil, and improving the sensitivity of the sensor.

[0127] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. An inductive displacement sensor for a magnetic bearing, characterized in that: include: A rotating shaft (4), a first probe (2) and a second probe (6), wherein the first probe (2) and the second probe (6) are both located on the outer periphery of the rotating shaft (4), the rotating shaft (4) has an axial direction, the first probe (2) is located at a first axial position, the second probe (6) is located at a second axial position, and along the axial direction, the second axial position is spaced apart from or connected to the first axial position; The first probe (2) is capable of detecting the axial displacement and radial displacement of the rotating shaft (4), and the second probe (6) is capable of detecting the radial displacement of the rotating shaft (4), so as to compare and compensate for the radial displacement of the rotating shaft (4) detected by the first probe (2).

2. The inductive displacement sensor of the magnetic bearing according to claim 1 is characterized in that: The surface of the first probe (2) facing the rotating shaft (4) is a first surface (A); in a vertical cross-sectional plane passing through the axis of the rotating shaft (4), the first surface (A) is not parallel to the axis of the rotating shaft (4); the outer peripheral surface of the rotating shaft (4) has a second surface (B); the second surface (B) is also not parallel to the axis of the rotating shaft (4); and the first surface (A) and the second surface (B) are opposite and parallel to each other, so that the axial and / or radial displacement of the rotating shaft (4) can be detected by the change of the spacing between the first surface (A) and the second surface (B) during the axial and / or radial movement of the rotating shaft (4); The surface of the second probe (6) facing the rotating shaft (4) is a third surface (C). In a vertical cross-sectional plane passing through the axis of the rotating shaft (4), the third surface (C) is parallel to the axis of the rotating shaft (4). The outer peripheral surface of the rotating shaft (4) has a fourth surface (D), and the fourth surface (D) is also parallel to the axis of the rotating shaft (4). The third surface (C) and the fourth surface (D) are opposite and parallel to each other, so that the radial displacement of the rotating shaft (4) can be detected by the change in the spacing between the third surface (C) and the fourth surface (D) during the radial movement of the rotating shaft (4).

3. The inductive displacement sensor of the magnetic bearing according to claim 2 is characterized in that: In a vertical cross-sectional plane passing through the axis of the rotating shaft (4), the outer normal of the second surface (B) extends away from the axis of the rotating shaft (4) and also extends away from the fourth surface (D), the outer normal of the fourth surface (D) is perpendicular to the axis, and the outer normal of the second surface (B) does not intersect with the outer normal of the fourth surface (D); The second surface (B) and the fourth surface (D) are connected along the axial direction of the rotating shaft (4), and protrusions protruding toward the radial outer periphery relative to the outer peripheral surface of the rotating shaft (4) are formed on the second surface (B) and the fourth surface (D).

4. The inductive displacement sensor of the magnetic bearing according to claim 3 is characterized in that: In a vertical cross-sectional plane passing through the axis of the rotating shaft (4), the second surface (B) is an inclined surface, one end of the second surface (B) is connected to the outer peripheral surface of the rotating shaft (4), and the other end gradually extends radially outward to connect with one end of the fourth surface (D), and the other end of the fourth surface (D) is higher than the outer peripheral surface of the rotating shaft (4) and forms a step with the outer peripheral surface of the rotating shaft (4), so that the outer diameter of the radial outer periphery of the fourth surface (D) is the largest part on the rotating shaft (4).

5. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: In a vertical cross-sectional plane passing through the axis of the rotating shaft (4), the first probe (2) is located on one side of the axis of the rotating shaft (4), and the second probe (6) is located on the other side of the axis of the rotating shaft (4).

6. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: Two first probes (2) are adjacent and spaced apart along the circumferential direction of the rotating shaft (4), forming a first probe unit, and two second probes (6) are adjacent to each other along the circumferential direction of the rotating shaft (4) forming a second probe unit. There are multiple first probe units and multiple second probe units, and the first probe units and the second probe units are staggered and spaced apart along the circumferential direction.

7. The inductive displacement sensor of the magnetic bearing according to claim 6, characterized in that: In the first probe unit, one of the adjacent first probes (2) is wound with a first probe coil (1), and another of the first probes (2) is wound with a second probe coil (7), and the first probe coil (1) and the second probe coil (7) are connected and conductive; in the second probe unit, one of the adjacent second probes (6) is wound with a third probe coil (5), and another of the second probes (6) is wound with a fourth probe coil (8), and the third probe coil (5) and the fourth probe coil (8) are connected and conductive.

8. The inductive displacement sensor for a magnetic bearing according to any one of claims 1 to 7, characterized in that: The invention comprises a first layer of stator silicon steel sheets (9) and a second layer of stator silicon steel sheets (10), wherein the first layer of stator silicon steel sheets (9) and the second layer of stator silicon steel sheets (10) are both annular structures, and the two are arranged in close contact along the axial direction of the rotating shaft, and the first probe (2) is arranged on the inner circumferential wall of the first layer of stator silicon steel sheets (9) so as to protrude radially inward, and the second probe (6) is arranged on the inner circumferential wall of the second layer of stator silicon steel sheets (10) so as to protrude radially inward.

9. The inductive displacement sensor of a magnetic bearing according to any one of claims 1 to 8, characterized in that: The rotating shaft (4) comprises an entire shaft section of a magnetic conductive structure, namely a rotating shaft magnetizer (3), wherein the rotating shaft magnetizer (3) extends from a shaft section opposite to the first probe (2) through a shaft section opposite to the second probe (6), so that both the first probe (2) and the second probe (6) are opposite to the rotating shaft magnetizer (3).

10. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: When the rotating shaft (4) is not offset, the initial inductances of two circumferentially adjacent first probes (2) are L 01 and L 02 , the input voltage is U s ,but: Where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of ​​the probe, μ0 represents the magnetic permeability, and δ1 and δ2 represent the air gaps formed by the initial air gap δ0 after the rotor displacement changes; When the rotating shaft (4) undergoes an axial displacement Δδ in the direction of the first probe (2), the magnetic conductive surfaces A1 and A2 of the two first probes (2) both become larger, and the air gaps δ1 and δ2 between the two first probes and the rotating shaft both decrease, δ1=δ2=(δ0-Δδ), and the changes in the self-inductance of the two first probe coils are respectively: ΔL2=ΔL1; Therefore, the axial output voltage is:

11. The inductive displacement sensor for a magnetic bearing according to claim 1, characterized in that: When the rotating shaft (4) does not deviate radially and is at the center of rotation, the initial gaps between the plurality of second probes (6) and the rotating shaft (4) are all δ′0, the number of turns of the coils are all W2, the magnetic conductive area is A′0, and the initial inductances of the two second probes located at the top are L 06 and L 07 The initial inductances of the two second probes located below are L 08 and L 09 , the input voltage is U s ,but: When the rotating shaft (4) undergoes a radial displacement Δδ′ downward, the air gap δ′1 between the two second probes located at the bottom and the rotating shaft decreases, the inductances L5 and L6 increase, the air gap δ′2 between the two second probes located at the top and the rotating shaft increases, and the inductances L3 and L4 decrease. At this time: Therefore, the radial output voltage of the second probes (6) of the second layer is: And suppose that at this time, the magnetic conductive surface of one of the first probes (2) is A′2, the gap is δ″2, and the magnetic conductive surface of the other first probe (2) is A′1, the gap is δ″1, A′1=A′2, δ″1=δ″2; At this time, the radial output voltage in the first probe of the first stator layer is: Finally, the radial output voltage U of the second stator layer is j0 The radial output voltage U′ in the upper wedge probe z0 , after normalization, the final radial detection output voltage of the sensor is: U′0=k*U j0 +(1-k)*U′ z0 , where k is a constant.

12. A magnetic bearing, characterized in that: An inductive displacement sensor comprising a magnetic bearing as claimed in any one of claims 1 to 11.

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