Inductive displacement sensor, magnetic suspension bearing assembly and compressor

Abstract

The invention provides an inductive displacement sensor, a magnetic suspension bearing assembly and a compressor, the inductive displacement sensor comprises a sensor stator and a plurality of sensor windings, the sensor stator comprises a yoke ring and a plurality of inner pole probes formed on the inner circumferential wall of the yoke ring, and the inner pole probes are distributed at intervals along the circumferential direction of the yoke ring; each sensor winding is wound on the yoke ring, and each inner pole probe is located between every two adjacent sensor windings. According to the invention, each sensor winding is wound on the yoke ring, and each inner pole probe is respectively positioned between each two adjacent sensor windings, so that the sensor adopts a back winding type design, and compared with an inner winding type design, the space between each two adjacent inner pole probes is saved; therefore, more pole probes can be arranged on the inner circumferential wall of the yoke ring, and the detection capability of the sensor is enhanced due to the increase of the number of the pole probes, so that the detection with smaller shaft diameter and more poles can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of magnetic suspension bearing, and particularly relates to an inductance type displacement sensor, a magnetic suspension bearing assembly and a compressor. BACKGROUND

[0002] The magnetic suspension bearing suspends the rotating shaft in the air through electromagnetic force in working, so that mechanical contact between the rotating shaft and the stator of the magnetic bearing is avoided. Compared with the mechanical bearing, the magnetic suspension bearing has the advantages of no mechanical wear, no lubrication, long service life, high rotating speed and strong reliability, and is widely used in the industrial manufacturing field of high-speed rotation such as flywheel energy storage, molecular pump, compressor, aerospace, etc. In order to continuously and stably rotate the rotating shaft in working, a displacement sensor is used to monitor the axial trajectory of the rotating shaft. At present, the non-contact displacement sensors widely used in the field of magnetic suspension bearing system mainly include eddy current displacement sensors and inductance type displacement sensors. The eddy current displacement sensor needs to use a high-frequency alternating current signal of 400 kHz or above, has weak anti-electromagnetic interference ability, is greatly affected by temperature, and thus has low detection accuracy. The inductance type 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 conductive area of the rotating shaft corresponding to the coil probe. The sensitivity and detection accuracy of the inductance type displacement sensor depend on the detection area of the sensor probe and the gap between the probe and the rotating shaft. However, the existing inductance type displacement sensors all adopt an inner-wound stator structure. Due to the limitation of the space structure, it is difficult to realize smaller shaft diameter and higher pole number detection with the traditional stator structure. SUMMARY

[0003] Therefore, the present application provides an inductance type displacement sensor, which can solve the technical problem that the existing inductance type displacement sensor adopts an inner-wound stator structure and is difficult to realize smaller shaft diameter and higher pole number detection.

[0004] In order to solve the above problems, the present application provides an inductance type displacement sensor, which comprises a sensor stator and a plurality of sensor windings. The sensor stator comprises a yoke ring and a plurality of inner pole column probes formed on the inner peripheral wall of the yoke ring. Each inner pole column probe is spaced apart along the circumference of the yoke ring. Each sensor winding is wound on the yoke ring. Each inner pole column probe is located between two adjacent sensor windings.

[0005] In some embodiments, the sensor stator is used to be sleeved on the periphery of a rotating shaft. The rotating shaft comprises a spherical segment. The spherical surface on which the outer surface of the spherical segment is located is a first spherical surface. The position of each inner pole column probe corresponds to the position of the spherical segment. Each inner pole column probe has an arc surface facing the rotating shaft. Each arc surface is located on a second spherical surface. The diameter of the second spherical surface is greater than the diameter of the first spherical surface.

[0006] In some embodiments, the sensor stator is configured to be sleeved on the outer periphery of the rotating shaft, the number of the inner pole probes is even, and two adjacent inner pole probes form a position detection group.

[0007] In some embodiments, the magnetic poles of two adjacent inner pole probes are different along the circumferential direction of the yoke ring.

[0008] In some embodiments, the sensor winding and the adjacent inner pole probe have a gap therebetween.

[0009] In some embodiments, a plurality of outer pole probes are formed on the outer peripheral wall of the yoke ring, and each outer pole probe is located between two adjacent sensor windings.

[0010] In some embodiments, the outer pole probe extends outwardly beyond the sensor winding along the radial direction of the yoke ring.

[0011] In some embodiments, the sensor winding and the adjacent outer pole probe have a gap therebetween.

[0012] The application also provides a magnetic bearing assembly comprising the inductive displacement sensor.

[0013] The application also provides a compressor comprising the magnetic bearing assembly.

[0014] The inductive displacement sensor, the magnetic bearing assembly, and the compressor have the following advantages:

[0015] By winding each sensor winding on the yoke ring of the sensor stator and locating each inner pole probe between two adjacent sensor windings, the sensor adopts a back-winding design. Compared with the inner-winding design in the prior art, the back-winding design saves the space between two adjacent inner pole probes, so that more inner pole probes can be arranged on the inner peripheral wall of the yoke ring. The increase in the number of inner pole probes enhances the detection capability of the sensor, so that smaller shaft diameter and more poles can be detected, and the structure is more compact. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other embodiments according to the provided drawings without creative labor.

[0017] Figure 1 A sectional view of an inductive displacement sensor and a rotating shaft according to an embodiment of the present application;

[0018] Figure 2 A structural schematic view of an inductive displacement sensor and a rotating shaft according to an embodiment of the present application;

[0019] Figure 3 A schematic view of a three-dimensional coordinate system established with reference to a rotating shaft arranged in an inductive displacement sensor according to an embodiment of the present application;

[0020] Figure 4 A working schematic view of an inductive displacement sensor according to an embodiment of the present application detecting radial and axial displacements of a rotating shaft in a three-dimensional spherical coordinate system;

[0021] Figure 5 A structural schematic view of an inductive displacement sensor according to an embodiment of the present application;

[0022] Figure 6 A structural schematic view of a rotating shaft according to an embodiment of the present application;

[0023] Figure 7 A structural schematic view of an inductive displacement sensor according to an embodiment of the present application installed in a housing.

[0024] The reference signs are as follows:

[0025] 1, sensor stator; 11, yoke ring; 12, inner pole column probe; 13, outer pole column probe; 2, sensor winding; 3, rotating shaft; 31, spherical segment; 32, first cylindrical segment; 33, second cylindrical segment; 4, camber surface; 5, housing. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work, fall within the scope of protection of the present application.

[0027] In the description of the present application, it should be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0028] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0029] In addition, it should be noted that the use of "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore it cannot be understood as a limitation on the scope of protection of the present application.

[0030] For reference Figures 1 to 7 As shown, according to the embodiment of the present application, an inductive displacement sensor is provided, which comprises a sensor stator 1 and a plurality of sensor windings 2, the sensor stator 1 comprises a yoke ring 11 and a plurality of inner pole column probes 12 formed on the inner circumferential wall of the yoke ring 11, each inner pole column probe 12 is spaced apart along the circumferential direction of the yoke ring 11, and each sensor winding 2 is wound on the yoke ring 11, and each inner pole column probe 12 is located between each two adjacent sensor windings 2.

[0031] In the technical scheme, the sensor winding 2 is wound on the yoke ring 11 of the sensor stator 1, and the inner pole column probe 12 is located between two adjacent sensor windings 2, so that the sensor adopts a back-wound design. Compared with the inner-wound design in the prior art, the back-wound design saves the space between the two adjacent inner pole column probes 12, so that more inner pole column probes 12 can be arranged on the inner circumferential wall of the yoke ring 11. The increase in the number of inner pole column probes 12 enhances the detection capability of the sensor, so that smaller shaft diameter and more poles can be detected, and the structure is more compact. It should be noted that the inner pole column probe 12 refers to the inner pole column acting as a probe, and the coil of each sensor winding 2 is wound in a self-induction manner.

[0032] For reference, Figure 2 , Figure 5 and Figure 6 , the sensor stator 1 is used to be sleeved on the outer periphery of the rotating shaft 3, the rotating shaft 3 includes a spherical segment 31, the spherical surface where the outer surface of the spherical segment 31 is located is a first spherical surface, the positions of the inner pole column probes 12 correspond to the position of the spherical segment 31, and each inner pole column probe 12 has an arc surface 4 facing the spherical segment 31, each arc surface 4 is on a second spherical surface, and the diameter of the second spherical surface is greater than that of the first spherical surface. The rotating shaft 3 further includes a first cylindrical segment 32 and a second cylindrical segment 33 connected on both sides of the spherical segment 31.

[0033] In the embodiment, because the positions of the inner pole post probes 12 all correspond to the position of the spherical segment 31, the sensor mainly detects the position of the rotating shaft 3 by detecting the position of the spherical segment 31. When the position of the rotating shaft 3 changes, the position of the spherical segment 31 relative to each inner pole post probe 12 changes synchronously. Because the curved surface 4 of each inner pole post probe 12 is on the second sphere, and when the first sphere moves relative to the second sphere, it is equivalent to a displacement in the axial and radial directions, the sensor can simultaneously detect the axial displacement and the radial displacement of the rotating shaft 3. That is, by improving the shape of the rotating shaft 3 and the shape of each inner pole post probe 12, the sensor can realize integrated detection in the axial and radial directions. At the same time, the spherical surface-to-spherical surface cooperation between each inner pole post probe 12 and the rotating shaft 3 forms a uniform air gap therebetween. If the position of the rotating shaft 3 changes, the change rate of the air gap therebetween remains constant, thereby avoiding the nonlinear change of the air gap caused by the mismatch of the curvature. Maintaining the uniformity of the air gap can also reduce the production cost (reduce the precise assembly process) and maintain the consistency of the measurement. Further, the spherical surface-to-spherical surface cooperation has a lower requirement for assembly alignment. Even if there is a slight mechanical tolerance, the spherical geometry can automatically "center". It should be noted that the working principle of the inductive displacement sensor of the present application is as follows: when the position of the rotating shaft 3 changes, the distance between the rotating shaft 3 and each inner pole post probe 12 changes, and then the impedance of each inner pole post probe 12 changes, so that the change in the position of the rotating shaft 3 is obtained according to the change in the impedance of the inner pole post probe 12.

[0034] Referring to Figure 1 As shown in the figure, the number of inner pole post probes 12 is even, and two adjacent inner pole post probes 12 form a position detection group. The two inner pole post probes 12 in each position detection group cooperate to detect the position of the rotating shaft 3.

[0035] In the technical solution, because each position detection group has two inner pole post probes 12 cooperating to detect the position of the rotating shaft 3, when the position of the rotating shaft 3 changes, the change amount of the inductance of the sensor winding 2 corresponding to a group of inner pole post probes 12 is twice the change amount of the inductance of the sensor winding 2 corresponding to a single inner pole post probe 12. Therefore, the sensitivity of the sensor can be improved.

[0036] Referring to Figure 1 As shown in the figure, the magnetic poles of two adjacent inner pole post probes 12 are different along the circumference of the yoke ring 11. This makes the polarities of the two inner pole post probes 12 in each position detection group different. Then the two magnetic poles in the same detection group form a loop, and there are two inner pole post probes 12 in the same direction for detection, so that the two inner pole post probes 12 in each position detection group cooperate to detect the position of the rotating shaft 3. Specifically, referring to Figure 1For example, the number of inner pole posts 12 in the present application is eight, and the eight inner pole posts 12 are uniformly distributed along the circumference of the yoke ring 11, each inner pole post 12 is 45° apart along the circumference, and each inner pole post 12 adopts NSNS… magnetic pole arrangement in the clockwise direction. Figure 1 In the same straight line, two opposite sensor windings 2 are connected in series, for example, two sensor windings 2 in the X direction and the Y direction are connected in series to form a loop, and the two sensor windings 2 are connected by differential mode. Among them, the magnetic flux of the two sensor windings 2 in the X direction and the Y direction is counterclockwise, from N to S.

[0037] Referring to Figure 1 , the sensor winding 2 and the adjacent inner pole post 12 have a gap. When the sensor is working, the cooling air flow can pass through the gap, which is beneficial to heat dissipation and can improve the reliability. Further, the inner pole post 12 extends beyond the sensor winding 2 along the radial inner side of the yoke ring 11, which can prevent the sensor winding 2 from interfering with the movement of the shaft 3.

[0038] Referring to Figures 1 to 3 , a plurality of outer pole posts 13 are formed on the outer circumferential wall of the yoke ring 11, and each outer pole post 13 is located between each adjacent two sensor windings 2.

[0039] In the present embodiment, the adjacent two sensor windings 2 are separated by the outer pole post 13 on the radial outer side of the yoke ring 11, which can prevent the adjacent two sensor windings 2 from moving left and right or entangling. It should be noted that the outer pole post 13 is actually an outer pole.

[0040] Referring to Figure 1 and Figure 7 , the outer pole post 13 extends beyond the sensor winding 2 along the radial outer side of the yoke ring 11.

[0041] In the technical scheme, a plurality of clamping grooves are formed on the inner circumferential wall of the shell 5 of the compressor, and each clamping groove is spaced apart along the circumference of the shell 5. Each outer pole post 13 is clamped in each clamping groove, thereby realizing radial positioning of the sensor and limiting movement of the stator in the radial direction (X / Y axis direction). When the outer pole post 13 extends beyond the sensor winding 2 along the radial outer side of the yoke ring 11, the outer part of the sensor winding 2 can be protected from rubbing contact with the shell 5, thereby improving the reliability of the sensor (especially in a high-temperature, high-vibration compressor environment). Specifically, the distance between the outer part of the sensor winding 2 and the shell 5 is usually greater than or equal to 0.5 mm.

[0042] Referring to Figure 1 , the sensor winding 2 and the adjacent outer pole post 13 have a gap. When the sensor is working, the cooling air flow can pass through the gap, which is beneficial to heat dissipation and can improve the reliability.

[0043] It should be noted that, to address the signal coupling issue during displacement detection of the smaller diameter rotating shaft 3, this application employs a three-dimensional spherical coordinate detection method. This method represents the displacement of the rotating shaft 3 in a three-dimensional spherical coordinate system, with the displacement expressed as angles (polar angle and azimuth angle) and radial eccentricity. The spherical coordinate displacement detection method can detect both the radial displacement of the rotating shaft 3 and the axial displacement through the radial eccentricity and azimuth angle in the three-dimensional spherical coordinate system. This, combined with the improved shapes of the rotating shaft 3 and each inner pole probe 12, enables integrated radial and axial detection of the sensor. The specific detection method is as follows:

[0044] by Figure 3 and Figure 4 For example, when the rotating shaft 3 is in the exact middle position, let one of the position detection groups detect point M, and the other position detection group, which is 180° opposite to it, detect point N. Then the spherical coordinates of these two points are expressed as M(ρ m ,β,θ),N(ρ n (β+180°, θ+180°), then the spherical coordinates of points M and N can be expressed as:

[0045] Point M:

[0046]

[0047] Where, ρ m Let M be the length of the line connecting point M and the origin O. The angle between the line connecting point M and the origin O and the Z-axis is β. Therefore, the coordinate point of point M corresponding to the Z-axis is Z. m =ρ m cosβ; The projection of the line connecting point M and the origin O onto the plane containing the X and Y axes makes an angle θ with the X-axis. Therefore, the coordinate point of point M corresponding to the X-axis is X. m =ρ m sinβcosθ, the coordinates of point M corresponding to the Y-axis are Y. m =ρ m sinβsinθ.

[0048] Point N:

[0049]

[0050] Where, ρ n Let be the length of the line connecting point N and the origin O. The angle between the line connecting point N and the origin O and the Z-axis is π + β. Therefore, the coordinate point of point N corresponding to the Z-axis is Z. n =ρ ncos (pi+beta); the projection of the line between the N point and the coordinate origin O in the plane of the X axis and the Y axis and the X axis is pi+theta, so the coordinate point of the X axis corresponding to the N point is X n = -p n sin (pi+beta) cos (pi+theta), the coordinate point of the Y axis corresponding to the N point is Y n = -p n sin (pi+beta) sin (pi+theta).

[0051] At this time, the spherical coordinate expression of the center position O' point corresponding to the rotating shaft is:

[0052]

[0053] That is, when the rotating shaft 3 is in the middle position, the spherical coordinate of the center position O point is O (0, 0, 0).

[0054] When the rotating shaft 3 deviates from the direction of the position detection group corresponding to the M point, the position point detected by the position detection group becomes the M' point, and the position point detected by the opposite position detection group becomes the N' point, so the spherical coordinates of the two points are M' (p m ', beta, theta), N (p n ', beta+180°, theta+180°), so the spherical coordinate expression of the center position O' point corresponding to the rotating shaft 3 is:

[0055]

[0056] The spherical coordinate of the center position O' point of the rotating shaft 3 is:

[0057] O' (p , , ).

[0058] It should be noted that the detection position point of each position detection group is located on the center symmetry line of the two inner pole column probes 12 of the position detection group.

[0059] The application also provides a magnetic suspension bearing assembly comprising the aforementioned inductive displacement sensor.

[0060] The application also provides a compressor comprising the aforementioned magnetic suspension bearing assembly.

[0061] It is easy for those skilled in the art to understand that the advantageous technical features of the above-mentioned modes can be freely combined and superimposed without conflict.

[0062] The above merely describes the preferred embodiments of the present application, but should not be used to limit the present application, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application. The above merely describes the preferred embodiments of the present application, but should not be used to limit the present application, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An inductive displacement sensor, characterized in that, The sensor includes a sensor stator (1) and multiple sensor windings (2). The sensor stator (1) includes a yoke (11) and multiple inner pole probes (12) formed on the inner peripheral wall of the yoke (11). Each inner pole probe (12) is distributed at intervals along the circumference of the yoke (11). Each sensor winding (2) is wound on the yoke (11). Each inner pole probe (12) is located between each two adjacent sensor windings (2).

2. The inductive displacement sensor according to claim 1, characterized in that, The sensor stator (1) is used to be sleeved on the periphery of the rotating shaft (3). The rotating shaft (3) includes a spherical segment (31). The spherical surface on which the outer surface of the spherical segment (31) is located is the first spherical surface. The positions of each inner pole probe (12) correspond to the positions of the spherical segment (31). Each inner pole probe (12) has an arc surface (4) facing the spherical segment (31). Each arc surface (4) is located on a second spherical surface. The diameter of the second spherical surface is larger than the diameter of the first spherical surface.

3. The inductive displacement sensor according to claim 1, characterized in that, The sensor stator (1) is used to be sleeved on the periphery of the rotating shaft (3). The number of the inner pole probes (12) is even. Two adjacent inner pole probes (12) form a position detection group. The two inner pole probes (12) in each position detection group cooperate to detect the position of the rotating shaft (3).

4. The inductive displacement sensor according to claim 3, characterized in that, Along the circumference of the yoke (11), the magnetic poles of two adjacent inner pole probes (12) are different.

5. The inductive displacement sensor according to claim 1, characterized in that, There is a gap between the sensor winding (2) and the adjacent inner pole probe (12).

6. The inductive displacement sensor according to any one of claims 1 to 5, characterized in that, Multiple external pole probes (13) are formed on the outer peripheral wall of the yoke (11), and each external pole probe (13) is located between two adjacent sensor windings (2).

7. The inductive displacement sensor according to claim 6, characterized in that, The outer pole probe (13) extends beyond the sensor winding (2) along the radial outer side of the yoke (11).

8. The inductive displacement sensor according to claim 6, characterized in that, There is a gap between the sensor winding (2) and the adjacent external pole probe (13).

9. A magnetic levitation bearing assembly, characterized in that it includes an inductive displacement sensor as described in any one of claims 1 to 8.

10. A compressor, characterized in that it includes the magnetic levitation bearing assembly of claim 9.

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