Axial radial displacement sensor and displacement measurement circuit

Abstract

The present invention discloses an axial radial displacement sensor and a displacement measurement circuit, comprising two magnetic conductors, each of which comprises a magnetic core and a magnetic yoke, and a first gap is formed between the magnetic core and the magnetic yoke; the two magnetic cores are arranged along the axial direction of the rotor, each magnetic core is provided with an induction coil, and the two magnetic cores are provided with an excitation coil, the excitation coil is configured to detect the radial displacement of the rotor, and the excitation magnetic field of the excitation coil forms a first magnetic circuit through the magnetic core, the rotor and the magnetic yoke; the two induction coils are configured to detect the axial displacement of the rotor, and the induction magnetic field of each induction coil forms a second magnetic circuit through the magnetic core, the rotor and the magnetic yoke. The axial radial displacement sensor is easy to be integrated with the stator of a magnetic suspension turntable, and the position information of the rotor can be detected through the cavity wall of a vacuum cavity by means of the first ring edge of the magnetic suspension turntable rotor. The axial radial displacement sensor has high sensitivity, and can reduce the number of displacement sensors and reduce production and installation costs.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic suspension, in particular to an axial radial displacement sensor and a displacement measurement circuit for rotor position detection. Background Art

[0002] In semiconductor manufacturing, on the one hand, the cleanliness of the wafer is very important, because the cleanliness of the wafer surface will affect the qualification rate of subsequent semiconductor processes and products. In order to achieve ultra-clean requirements, wafers of silicon or other semiconductor materials must be processed in a controlled ultra-clean atmosphere. For example, in the wafer manufacturing process, one manufacturing step is to anneal the wafer after ion implantation. Doping imposes strain on the crystal structure. If the stress cannot be released quickly, it will cause undesirable changes in the resistivity of the ion doping. At present, rapid thermal processing (RT) is usually used for annealing. On the other hand, the processing uniformity of the wafer is very important. In order to produce uniformity, the wafer is usually rotated around the vertical axis or z-axis of the center of the wafer when processing the wafer. Rotation is also used for other wafer processing, such as chemical vapor deposition, heat treatment, ion implantation doping and other technical doping. In order to meet the stringent requirements of ultra-cleanliness and processing uniformity in semiconductor process manufacturing, semiconductor processing equipment preferably uses a magnetic levitation turntable with contactless rotation drive. The magnetic levitation turntable includes a stator and a rotor, and the stator is used to generate a magnetic field to drive the rotor and the carrier to rotate and suspend. According to the relative position difference between the stator and the rotor, the magnetic levitation turntable can be divided into an inner rotor magnetic levitation turntable and an outer rotor magnetic levitation turntable.

[0003] In order to achieve stable suspension of the rotor, accurate position information of the rotor must be provided to the control system. Generally, the required rotor position information is obtained through non-contact displacement sensor technology. At present, the displacement sensor of the magnetic suspension turntable includes multiple axial sensors and multiple radial sensors. The displacement sensor includes a sensor probe, which is installed radially or axially on the vacuum cavity of the semiconductor processing equipment. The vacuum cavity is used to form a closed cavity with the semiconductor processing equipment to isolate the rotor and the stator, so that the rotor rotates in the closed vacuum cavity; however, when the displacement sensor is assembled on the cavity wall and cavity bottom of the vacuum cavity, it is necessary to form a through hole on the vacuum cavity and use a sealing ring for sealing; due to the ultra-clean and high-temperature environment requirements of the semiconductor processing equipment, the sealing ring needs to use a high-temperature resistant fluororubber sealing ring (high cost), and needs to be replaced after a long time of use, which leads to a high cost of displacement sensor assembly, and the installation process of the displacement sensor replacing the sealing ring is cumbersome, and there are problems such as calibration and installation errors of sensor reassembly and poor sealing. In addition, multiple connection cables of multiple displacement sensors are scattered around the rotor, the wiring is messy, and it is not convenient to set up and control the sensor cable and the sensor conditioning circuit. Summary of the invention

[0004] In order to overcome the defects in the prior art, an embodiment of the present invention provides an axial radial displacement sensor and a displacement measurement circuit, which are used to solve at least one of the above problems.

[0005] According to one aspect of the present invention, there is provided an axial radial displacement sensor, comprising two magnetic conductors, each of which comprises a magnetic core and a magnetic yoke, with a first gap between the magnetic core and the magnetic yoke; the two magnetic cores are arranged along the axial direction of the rotor, each of which is provided with an induction coil, and the two magnetic cores are provided with an excitation coil together, the excitation coil is configured to detect the radial displacement of the rotor, and the excitation magnetic field of the excitation coil constitutes a first magnetic circuit through the magnetic core, the rotor and the magnetic yoke; the two induction coils are configured to detect the axial displacement of the rotor, and the induced magnetic field of each induction coil constitutes a second magnetic circuit through the magnetic core, the rotor and the magnetic yoke.

[0006] Furthermore, the magnetic conductor also includes a magnetic matrix, and one end of the magnetic core and one end of the magnetic yoke are connected through the magnetic matrix.

[0007] Furthermore, the cross section of the magnetic core is square, each of the magnetic conductors includes two magnetic yokes, the cross section of the magnetic yoke is square, and the two magnetic yokes are arranged on both sides of the magnetic core.

[0008] Furthermore, the axial height of the magnetic core is the same as the axial height of the magnetic yoke, the upper surface of the magnetic core is flush with the upper surface of the magnetic yoke, and the cross-sectional area of ​​the magnetic core is 1-3 times the cross-sectional area of ​​the magnetic yoke.

[0009] Furthermore, the excitation coil is arranged at one end of the magnetic core close to the rotor, and the induction coil is arranged at a side of the excitation coil facing away from the rotor.

[0010] Furthermore, a sum of a first distance between the rotor and the magnetic core and a second distance between the rotor and the magnetic yoke is less than or equal to a third distance between the magnetic core and the magnetic yoke.

[0011] Furthermore, an auxiliary coil is sleeved on the yoke of each of the magnetic conductors, and the auxiliary coil is connected in series with the induction coil on the magnetic core, so that the magnetic field generated by the induction coil on the magnetic core and the magnetic field generated by the auxiliary coil on the yoke are superimposed and enhanced.

[0012] Furthermore, the rotor includes a rotor body and a first ring edge formed on the rotor body, the axial height of the first ring edge is between the upper surface of one of the magnetic cores and the lower surface of the other magnetic core, and the range of axial movement of the first ring edge is: the upper surface of the first ring edge does not exceed the upper surface of one of the magnetic cores, and the lower surface of the first ring edge does not exceed the lower surface of the other magnetic core.

[0013] Furthermore, the two magnetic conductors are an integrally formed magnetic tank structure, the cross section of the magnetic yoke is a square ring or a circular ring, and the cross section of the magnetic core is a square.

[0014] Furthermore, it also includes a shell, in which a containing space is formed, and the magnetic tank structure is installed in the containing space and is close to one end of the shell.

[0015] According to another aspect of the present invention, a displacement measurement circuit is provided, comprising a radial measurement circuit for measuring radial displacement and an axial measurement circuit for measuring axial displacement, wherein the radial measurement circuit comprises an excitation coil of the axial radial displacement sensor, and the axial measurement circuit comprises two induction coils of the axial radial displacement sensor.

[0016] Furthermore, the radial measurement circuit includes a first amplifier, a first resistor and an excitation source, one end of the excitation coil is electrically connected to one end of the excitation source, the other end of the excitation coil is electrically connected to the first resistor and an input end of the first amplifier, and the other end of the first resistor is electrically connected to the other end of the excitation source and the other input end of the first amplifier and is grounded.

[0017] Furthermore, it includes two radial measurement circuits for measuring radial displacement, one of the radial measurement circuits includes an excitation coil of the axial radial displacement sensor, denoted as the first measuring coil, and the other radial measurement circuit includes another excitation coil of the axial radial displacement sensor, denoted as the second measuring coil, and the output ends of the two radial measurement circuits are respectively electrically connected to the in-phase input end and the inverting input end of the first differential amplifier.

[0018] Furthermore, the two induction coils are recorded as a first detection coil and a second detection coil, and the axial measurement circuit also includes a second differential amplifier, one end of the first detection coil is electrically connected to one end of the second detection coil and grounded, the other end of the first detection coil is electrically connected to the non-inverting input end of the second differential amplifier, and the other end of the second detection coil is electrically connected to the inverting input end of the second differential amplifier.

[0019] The beneficial effects of the present invention are as follows: Compared with the prior art, the present invention forms an axial radial displacement sensor and a displacement measurement circuit, the axial radial displacement sensor integrates an excitation coil and two induction coils, and constructs a first magnetic circuit of an excitation magnetic field and a second magnetic circuit of an induction magnetic field through a magnetic core and a magnetic yoke of a magnetic conductor, forming an axial radial integrated displacement sensor capable of detecting axial displacement and radial displacement. The axial radial displacement sensor is convenient to be integrated with the stator of a magnetic suspension turntable, and with the help of the first ring edge of the rotor of the magnetic suspension turntable, the position information of the rotor can be detected through the cavity wall of the vacuum cavity. The organic combination of the axial radial displacement sensor and the stator structure has a compact structure and high sensitivity, and can reduce the number of displacement sensors and reduce production and installation costs. The magnetic suspension turntable using the axial radial displacement sensor of the present invention does not need to make a through hole on the vacuum cavity and use a fluororubber sealing ring, and does not need to replace the sealing ring, which solves the problems of recalibration and installation errors after assembling the sensor, can better meet the ultra-clean and high temperature environment requirements of semiconductor processing equipment, and can solve the problem of messy cable connections of multiple displacement sensors, and can also greatly reduce the number of sensors used in the magnetic suspension turntable.

[0020] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a structural schematic diagram of an embodiment of a magnetic suspension turntable in the prior art;

[0023] Figure 2 The structure of an embodiment of the axial radial displacement sensor of the present invention is shown in FIG. Figure 1 ;

[0024] Figure 3 The structure of an embodiment of the axial radial displacement sensor of the present invention is shown in FIG. Figure 2 ;

[0025] Figure 4 is a schematic diagram of the change in magnetic flux of the induction coil of the shaft radial displacement sensor when the rotor moves axially downward in an embodiment of the present invention;

[0026] Figure 5is a schematic diagram of the change in magnetic flux of the induction coil of the axial radial displacement sensor when the rotor moves axially upward in an embodiment of the present invention;

[0027] Figure 6 The structure of another embodiment of the central axis radial displacement sensor of the present invention is shown in FIG. Figure 1 ;

[0028] Figure 7 The structure diagram of a magnetic suspension turntable using the axial radial displacement sensor of the present invention is shown in FIG. Figure 1 ;

[0029] Figure 8 The structure diagram of a magnetic suspension turntable using the axial radial displacement sensor of the present invention is shown in FIG. Figure 2 ;

[0030] Fig. 9 The structure diagram of a magnetic suspension turntable using the axial radial displacement sensor of the present invention is shown in FIG. Figure 3 ;

[0031] Fig.10 It is a structural schematic diagram of a first suspension control component of an embodiment of a magnetic suspension turntable using the axial radial displacement sensor of the present invention;

[0032] Fig.11 It is a structural schematic diagram of another embodiment of a magnetic suspension turntable using the axial radial displacement sensor of the present invention;

[0033] Fig.12 yes Fig.11 The schematic diagram of the structure of the shaft radial displacement sensor at A in the middle;

[0034] Fig.13 It is a schematic structural diagram of a rotor of an embodiment of a magnetic suspension turntable to which the axial radial displacement sensor of the present invention is applied;

[0035] Fig.14 It is a structural schematic diagram of a stator of an embodiment of a magnetic suspension turntable to which the axial radial displacement sensor of the present invention is applied;

[0036] Fig.15 It is a structural schematic diagram of a second suspension control assembly of an embodiment of a magnetic suspension turntable using the axial radial displacement sensor of the present invention;

[0037] Fig.16 The structure diagram of another embodiment of the central axis radial displacement sensor of the present invention is as follows Figure 1 ;

[0038] Fig.17 The structure diagram of another embodiment of the central axis radial displacement sensor of the present invention is as follows Figure 2 ;

[0039] Fig.18It is a structural schematic diagram of an embodiment of an axial measurement circuit in a displacement measurement circuit of the present invention;

[0040] Fig.19 It is a structural schematic diagram of another embodiment of the axial measurement circuit in the displacement measurement circuit of the present invention;

[0041] Fig. 20 It is a structural schematic diagram of a radial measurement circuit in a displacement measurement circuit in the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a system, product or device comprising a series of units is not necessarily limited to those units clearly listed, but may include other units that are not clearly listed or inherent to these products or devices.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0045] The drawings in this disclosure are not drawn strictly according to the actual scale, and the specific size and quantity of each structure can be determined according to actual needs. The drawings described in this disclosure are only schematic diagrams.

[0046] In the prior art, see Figure 1 An embodiment of a magnetic suspension turntable includes a rotor 120' and a stator 130', wherein the stator 130' is arranged around the rotor 120' or the rotor 120' is arranged around the stator 130'. Figure 1The example in the figure shows a case where the stator 130' is arranged around the rotor 120' and the inner rotor 120'. The stator 130' includes at least two magnetic stator substrates 112' and a permanent magnet 111'. The permanent magnet 111' is clamped between the two magnetic stator substrates 112' in the axial direction of the stator to provide a permanent magnetic bias magnetic field. The stator 130' also includes a plurality of stator poles and a plurality of winding coils. The plurality of winding coils include a plurality of rotating windings for rotation drive control and a plurality of suspension windings for suspension control. The rotation and suspension control principle of the magnetic suspension turntable can be referred to patent documents CN124210580A and CN126207927A, which will not be repeated here. In particular, the magnetic levitation turntable also includes a vacuum chamber 130', which includes an inner ring body 131' (inner chamber wall), an outer ring body 132' (outer chamber wall) and a connecting plate 133' (chamber bottom) connecting the bottom of the inner ring body 131' and the bottom of the outer ring body 132', and a U-shaped annular space is formed between the inner ring body 131' and the outer ring body 132' to accommodate the rotor 120', wherein the outer ring body 132' is a thin wall for isolating the stator 130' and the rotor 120'. The displacement sensor of the magnetic suspension turntable includes multiple axial sensors and multiple radial sensors. The displacement sensor includes a sensor probe, which is radially or axially mounted on the vacuum chamber of the semiconductor processing equipment. The vacuum chamber is used to form a closed chamber with the semiconductor processing equipment to isolate the rotor and the stator, so that the rotor rotates and works in the closed vacuum chamber. However, when the displacement sensor is assembled on the inner wall and the bottom of the vacuum chamber, it is necessary to form a through hole on the vacuum chamber and use a sealing ring for sealing. Due to the ultra-clean and high-temperature environment requirements of the semiconductor processing equipment, the sealing ring needs to use a high-temperature resistant fluororubber sealing ring (high cost), and needs to be replaced after a long time of use, which leads to a high cost of displacement sensor assembly, and the installation process of replacing the sealing ring of the displacement sensor is cumbersome, and there are problems such as calibration and installation errors of sensor reassembly and poor sealing. In addition, multiple connection cables of multiple displacement sensors are scattered around the rotor, the wiring is messy, and it is not convenient to set up and control the sensor cables and sensor conditioning circuits.

[0047] To solve the above problems, see Figure 2-Figure 5The present invention provides an axial radial displacement sensor, comprising two magnetic conductors 1, each of which comprises a magnetic core 11 and a magnetic yoke 12, and a first gap 13 is provided between the magnetic core 11 and the magnetic yoke 12; the two magnetic cores 11 are arranged along the axial direction of the rotor 2, each magnetic core 11 is provided with an induction coil L2, and the two magnetic cores 11 are provided with an excitation coil L1, the excitation coil L1 is configured to detect the radial displacement of the rotor 2, and the excitation magnetic field of the excitation coil L1 forms a first magnetic circuit through the magnetic core 11, the rotor 2 and the magnetic yoke 12, the two induction coils L2 are configured to detect the axial displacement of the rotor 2, and the induction magnetic field of each induction coil L2 forms a second magnetic circuit through the magnetic core, the rotor and the magnetic yoke. The axial radial displacement sensor of the present invention integrates the excitation coil and the two induction coils together, and constructs the first magnetic circuit of the excitation magnetic field and the second magnetic circuit of the induction magnetic field through the magnetic core and the magnetic yoke of the magnetic conductor, forming an axial radial integrated displacement sensor capable of detecting axial displacement and radial displacement. The axial radial displacement sensor is easy to be integrated with the stator of the magnetic levitation turntable. With the help of the first ring edge of the magnetic levitation turntable rotor, the position information of the rotor can be detected through the cavity wall of the vacuum cavity. The axial radial displacement sensor is organically combined with the stator structure, has a compact structure, high sensitivity, and can reduce the number of displacement sensors and reduce production and installation costs.

[0048] The principle of measuring the radial displacement of the rotor by exciting the coil is as follows: Figure 2 and Figure 3 , because the excitation coil covers the height of the rotor (the first ring edge of the rotor in the specific implementation) in the axial direction, when the rotor moves radially, the magnetic flux density of the excitation coil remains constant, and the magnetomotive force follows the change of magnetic resistance. The change of magnetic resistance depends on the air gap between the rotor (for example, the first ring edge of the turntable rotor) and the magnetic core of the excitation coil, and the change of magnetomotive force caused by the change of air gap is approximately linearly related to the radial displacement of the rotor. Therefore, the radial displacement of the rotor can be detected based on the magnetomotive force (current) output of the excitation coil. The principle of measuring the axial displacement of the rotor through two induction coils is as follows: See Figure 4 and Figure 5 When the rotor is located in the middle of the two induction coils, the magnetic flux density of the two induction coils is the same, and the voltage of the differential output of the two induction coils is zero; when the rotor moves axially downward or upward, one induction coil (for example Figure 4 The induction coil in the lower middle or Figure 5 The magnetic flux density of the induction coil in the upper middle) increases, and the magnetic flux density of the other induction coil (e.g. Figure 4 The induction coil in the upper middle or Figure 5 The magnetic flux density of the induction coil in the middle and lower part decreases, and the magnetic flux density of the two induction coils changes and is no longer equal. The value of the differential output is no longer 0, but is approximately linearly related to the axial displacement of the rotor. Therefore, the axial displacement of the rotor can be detected based on the differential output of the two induction coils.

[0049] According to the embodiment of the present disclosure, the magnetic conductor further includes a magnetic matrix 14, and the magnetic conductor 1 further includes a magnetic matrix 14, and one end of the magnetic core 11 and one end of the magnetic yoke 12 are connected through the magnetic matrix 14. Preferably, see Figure 2 The yoke, magnetic core and magnetic matrix are an integrated structure. The magnetic yoke and magnetic core are connected by the magnetic matrix, which can play a better role in magnetic concentration and magnetic conduction.

[0050] According to the embodiment of the present disclosure, see Figure 3 , the cross section of the magnetic core 11 is square, and each magnetic conductor 1 includes two magnetic yokes 12, the cross section of the magnetic yoke 12 is square, and the two magnetic yokes 12 are arranged on both sides of the magnetic core 11. In this way, the magnetic conductor is E-shaped as a whole. Since the magnetic core, magnetic yoke and magnetic matrix are used for magnetic conduction, they can be made of multiple layers of silicon steel sheets stacked to reduce the interruption of the eddy current path, significantly reduce the eddy current effect, and reduce heat loss. In this embodiment, the shape of the magnetic core and the magnetic yoke is square, such as a rectangle or a square, but it is not limited to this. In other embodiments, it can also be designed as other regular or irregular shapes according to actual needs.

[0051] According to the embodiment of the present disclosure, see Figure 3 , the axial height of the magnetic core 11 is the same as the axial height of the magnetic yoke 12, and the upper surface of the magnetic core 11 is flush with the upper surface of the magnetic yoke 12. The cross-sectional area of ​​the magnetic core 11 is 1-3 times the cross-sectional area of ​​the magnetic yoke 12. In this way, the magnetic core and the magnetic yoke have the same height along the axial direction of the rotor and are located in the same horizontal plane, which can simplify the manufacturing process and ensure uniform magnetic field distribution of the axial radial displacement sensor. The cross-sectional area of ​​the magnetic core is 1 times the cross-sectional area of ​​the magnetic yoke, that is, the cross-sectional areas of the two are the same. Since the total magnetic flux of the magnetic core is divided into two parts and is distributed to the two magnetic yokes, in principle, in order to avoid magnetic saturation of the core material, the area of ​​the magnetic core should be larger than the area of ​​the magnetic yoke. Therefore, preferably, the cross-sectional area of ​​the magnetic core 11 is 1-3 times the cross-sectional area of ​​the magnetic yoke 12. More preferably, the cross-sectional area of ​​the magnetic core is twice the cross-sectional area of ​​the magnetic yoke. More preferably, see Figure 3 The shape and size of the magnetic cores of the two magnetizers are exactly the same. At the same time, the shape and size of the magnetic yokes of the two magnetizers are also the same. In this way, the magnetic circuit structure of the two induction coils along the axial direction of the rotor is symmetrical, thereby ensuring the symmetry of the axial displacement measurement and facilitating the signal processing of the sensor.

[0052] According to the embodiment of the present disclosure, see Figure 2 , the excitation coil L1 is arranged at one end of the magnetic core 11 close to the rotor 2, and the induction coil L2 is arranged at the side of the excitation coil L1 facing away from the rotor 2. In this way, the magnetic flux generated by the excitation coil is more concentrated on one side of the rotor, reducing leakage magnetic flux, so as to improve the sensitivity of sensor detection.

[0053] According to the embodiment of the present disclosure, see Figure 2, the sum of the first distance point d1 between the rotor 2 and the magnetic core 11 and the second distance d2 between the rotor 2 and the magnetic yoke 12 is less than or equal to the third distance d3 between the magnetic core and the magnetic yoke. In this way, the magnetic flux generated by the excitation coil forms a magnetic circuit after passing through the rotor, avoiding the magnetic flux directly forming a magnetic circuit by the magnetic yoke without passing through the rotor, thereby ensuring the magnetic flux for the sensor to detect the rotor displacement, so as to improve the sensitivity of the sensor detection.

[0054] According to the embodiment of the present disclosure, see Figure 6 , an auxiliary coil L3 is sleeved on the yoke 12 of each of the magnetic conductors 1, and the auxiliary coil L3 is connected in series with the induction coil L2 on the magnetic core 11, and the magnetic field generated by the induction coil L2 on the magnetic core 11 is superimposed and enhanced with the magnetic field generated by the auxiliary coil L3 on the yoke 12. In this way, the axial radial displacement sensor may also include 1 excitation coil, 2 induction coils and 4 auxiliary coils, and the 2 auxiliary coils of each magnetic conductor are connected in series with the induction coil. In other embodiments, the axial radial displacement sensor may also include 1 excitation coil, 2 induction coils and 2 auxiliary coils, and the 1 auxiliary coil of each magnetic conductor is connected in series with the induction coil. In this way, by adding auxiliary coils to the yoke and superimposing and enhancing the magnetic field generated by the auxiliary coil on the yoke with the magnetic field generated by the induction coil on the magnetic core, the output signal, such as the output voltage or the output current, can be enhanced, thereby achieving the purpose of improving the sensitivity of the axial radial displacement sensor in detecting axial displacement.

[0055] In the above embodiment, an excitation coil is provided on the two magnetic cores, but it is not limited thereto. In other embodiments, an excitation coil or two excitation coils may be provided on the magnetic yoke, or an excitation coil may be provided on both the magnetic core and the magnetic yoke. By connecting different excitation coils in series or in parallel, the purpose of adjusting the expected output magnetic motive force is achieved.

[0056] According to the embodiment of the present disclosure, see Fig.13 The rotor includes a rotor body 21 and a first ring edge 22 formed on the rotor body. The axial height of the first ring edge 22 is between the upper surface of one magnetic core 11 and the lower surface of the other magnetic core 11, and the axial movement range of the first ring edge 22 is: the upper surface of the first ring edge 22 does not exceed the upper surface of one magnetic core 11, and the lower surface of the first ring edge 22 does not exceed the lower surface of the other magnetic core 11. In this way, the axial movement of the rotor can be ensured to be within the axial height range of the excitation coil, that is, it will not affect the radial displacement measurement of the excitation coil, and improve the accuracy of sensor detection.

[0057] According to the embodiment of the present disclosure, see Figure 7-Figure 15A magnetic suspension turntable using the axial radial displacement sensor of the present invention comprises a stator 3 and a rotor 2, wherein the rotor 2 has a first rim 22 protruding toward the stator 3, and the stator 3 comprises a first suspension control component 32, wherein the first suspension control component 32 is configured to apply an axially actively controlled suspension force to the first rim 22, and the first suspension control component 32 comprises two stacked stator substrates A, which are respectively denoted as a first stator substrate 3210 and a second stator substrate 3220, wherein each stator substrate A has a plurality of stator substrates spaced apart along the circumference of the rotor 2 on one side thereof facing the rotor 2. The stator poles A on the two stator substrates A are staggered and cross-arranged along the circumference of the rotor 2, the stator pole A on the first stator substrate 3210 is recorded as the first stator pole 3211, and the stator pole A on the second stator substrate is recorded as the second stator pole 3221. The first stator pole 3211 and the second stator pole 3221 are staggered along the axial direction of the rotor. Along the circumference of the rotor, a second stator pole 3221 is arranged between the two first stator poles 3211, and a first stator pole 3211 is arranged between the two second stator poles 3221. The magnetic levitation turntable also includes the above-mentioned axial radial displacement sensor 100, wherein the magnetic core 11 and the magnetic yoke 12 of a magnetic conductor 1 of the axial radial displacement sensor 100 are magnetically connected to a stator substrate A, for example, magnetically connected to the second stator substrate 3220, wherein the magnetic connection means that the magnetic core 11 and the magnetic yoke 12 and the second stator substrate 3220 can be mutually magnetically conductive. The magnetic core 11 and the magnetic yoke 12 of another magnetic conductor are integrally formed with the stator pole A of another stator substrate A, for example, the magnetic core 11 and the magnetic yoke 12 of another magnetic conductor are integrally formed with the first stator pole 3211 of the first stator substrate 3210, wherein the integral forming means that the magnetic core 11 and the magnetic yoke 12 are directly formed on the first stator pole 3211 of the first stator substrate 3210. The excitation coil L1 is configured to detect the radial displacement of the rotor, and the two induction coils L2 are configured to detect the axial displacement of the rotor. In this way, the mutual induction magnetic field between the excitation coil and the induction coil changes when the rotor undergoes radial or axial displacement. The radial displacement of the rotor is measured by the excitation coil, and the axial displacement of the rotor is measured by the two induction coils, so that the function of measuring the radial and axial displacements of the rotor can be realized. At the same time, the displacement measurement is integrated with the stator of the magnetic suspension turntable. With the help of the first ring edge of the rotor, the axial radial displacement sensor can detect the position information of the rotor through the cavity wall of the vacuum cavity, thereby realizing the organic combination of the rotor position detection and the stator structure, with a compact structure and high sensitivity. Since the two induction coils measuring the axial displacement of the rotor are located at the same angular position on the circumference of the rotor, the amount of calculation of the processor during the axial displacement measurement can be reduced.The embodiment of the present invention does not need to make a through hole on the vacuum chamber and use a fluororubber sealing ring, nor does it need to replace the sealing ring. It solves the problems of recalibration and installation errors after assembling the sensor, can better meet the ultra-clean and high-temperature environment requirements of semiconductor processing equipment, can solve the problem of messy cable connections of multiple displacement sensors, and can greatly reduce the number of sensors used in the magnetic levitation turntable.

[0058] According to the embodiment of the present disclosure, see Figure 7 and Fig.12 The excitation magnetic field of the excitation coil L1 forms a first magnetic circuit via two magnetic cores, the first ring edge 22, the stator pole A (for example, the second stator pole 3221) and the yoke 12; the induced magnetic field of one induction coil L2 forms a second magnetic circuit via the magnetic core 11, the first ring edge 22, and the yoke 12; the induced magnetic field of the other induction coil L2 forms another second magnetic circuit via the magnetic core 11, the first ring edge 22, and the stator pole A (for example, the second stator pole 3221).

[0059] According to the embodiment of the present disclosure, see Fig.10 , Fig.11 and Fig.12 , a first gap 13 is formed on the stator pole A of the other stator substrate A on the side facing the first ring edge 22, and the first gap 13 defines a magnetic core 11 on the stator pole A. In this way, by defining the magnetic core through the first gap 13, the induction coil and the excitation coil can be directly integrated on the stator pole A to form an inductive sensor, without the need to configure a sensor housing, an iron core and other coil fixing structures. Since the stator poles A on the two stator substrates A are alternately arranged in the circumferential direction and do not overlap in the rotor axial direction, it is only necessary to define the magnetic core through the first gap 13 on one stator pole A. In this embodiment, an example is given in which the magnetic core 11 is defined by the first gap 13 on the second stator pole 3221 of the second stator substrate 3220, and another magnetic core and a yoke are formed above the magnetic core along the rotor axial direction. However, it is not limited to this. In other embodiments, the magnetic core 11 can also be defined by the first gap 13 on the first stator pole 3211 of the first stator substrate 3210. At this time, the magnetic core 11 is axially above the other magnetic core 11. In this embodiment, an embodiment is provided in which the magnetic core is defined by forming a first gap 13 on the stator magnetic pole A, so that the structural parameters of the original first suspension control component (for example, the design parameters of the air gap between the stator magnetic pole A and the first ring edge) can be maintained.

[0060] According to the embodiment of the present disclosure, a second gap 13' is formed on the stator magnetic pole A of the other stator substrate A on the side facing the rotor, and the first gap 13 and the second gap 13' define two magnetic yokes 12 on the stator magnetic pole A. In this way, the magnetic yoke is defined by the first and second gaps, and the magnetic circuits of the induction coil and the excitation coil pass through the magnetic yoke, which plays a role in magnetic conduction and magnetic concentration, thereby reducing the diffusion of the excitation magnetic field and the induced magnetic field on the stator magnetic pole A. Preferably, see Fig.12 , the first gap 13 and the second gap 13' both extend from the end surface of the stator pole A in the direction away from the rotor 2, and the length of the second gap 13' is greater than or equal to the length of the first gap 13. In this way, the magnetic field generated by the induction coil and the excitation coil can better return to the S stage from the N stage through the second magnetic yoke, and play a better role in magnetic conduction and magnetic concentration. In the above embodiment, an embodiment of 1 excitation coil and 2 induction coils is given. However, it is not limited to this. In other embodiments, the axial radial displacement sensor can also include an excitation coil group and an induction coil group, wherein the excitation coil group includes at least one excitation coil L1, and the induction coil group includes at least two induction coils L2.

[0061] Since the stator magnetic poles A on the two stator substrates A are staggered and cross-arranged along the circumferential direction of the rotor 2, the first stator magnetic pole 3211 on the first stator substrate 3210 and the second stator magnetic pole 3221 on the second stator substrate 3220 are staggered along the axial direction of the rotor. From the bottom perspective of the magnetic suspension turntable, an embodiment such as Fig.11 and Fig.12 As shown, the axial radial displacement sensor is arranged on the second stator magnetic pole 3221 of the second stator substrate in the X+, X- and Y+, Y- directions. Fig.11 In the figure, it can be seen that the magnetic core 11 and the second stator magnetic pole 3221 are integrally formed. Figure 2 and Figure 7 As shown, the axial radial displacement sensor is arranged on the first stator magnetic pole 3211 of the first stator substrate 3210. Figure 7 It can be directly seen that the magnetic core 11 and the magnetic yoke 12 are integrally formed with the first stator substrate 3210.

[0062] The present invention does not limit the number of stator poles A of each stator substrate A. Preferably, according to the embodiment of the present disclosure, each stator substrate A is formed with 3 or 4 stator poles A arranged at equal intervals along the circumference of the rotor on one side facing the rotor. When the stator pole A on one stator substrate A is recorded as the first stator pole and the stator pole A on the other stator substrate A is recorded as the second stator pole, refer to Figure 7, the four first stator poles 3211 and the four second stator poles 3221 are arranged crosswise, and the first suspension control assembly has a total of eight stator poles A. The four first stator poles 3211 and the four second stator poles 3221 are staggered in the axial direction, and in the circumferential direction, one second stator pole 3221 is arranged between two adjacent first stator poles 3211, and one first stator pole 3211 is arranged between two adjacent second stator poles 3221.

[0063] According to the embodiment of the present disclosure, see Figure 7 and Fig.11 The magnetic suspension turntable includes four axial radial displacement sensors, which are correspondingly arranged on the four first stator magnetic poles 3211 or the four second stator magnetic poles 3221. The four axial radial displacement sensors are divided into two mutually orthogonal groups, and each group includes two axial radial displacement sensors arranged radially symmetrically. In this way, the four axial radial displacement sensors constitute two displacement sensor pairs, each displacement sensor pair includes two axial radial displacement sensors, and the two displacement sensor pairs are arranged orthogonally to each other. In this way, the position detection of the rotor in two orthogonal directions (x degree of freedom direction and y degree of freedom direction) can be realized, and a pair of differential sensors are formed by using two radially symmetrical axial radial displacement sensors to form a differential signal, which can achieve the purpose of improving the sensitivity of radial displacement detection. At the same time, the four axial radial displacement sensors are evenly distributed in the circumferential direction. When the axial displacement of the rotor is detected by the four axial radial displacement sensors, the average can be calculated to eliminate the problem of inaccurate axial displacement detection due to rotor tilt.

[0064] According to the embodiment of the present disclosure, see Figure 8 , Fig. 9 , Fig.14 and Fig.15 The magnetic levitation turntable further includes a second levitation control component 33, which is configured to apply a radial levitation force to the rotor 2. The second levitation control component 33 includes a stator substrate B 330, a plurality of stator poles B 331 protruding from the stator substrate B 330 toward the rotor 2, and a control winding B 332 disposed on the stator poles B 331. The plurality of stator poles B 331 are evenly disposed in the circumferential direction and extend in the circumferential direction. For this structure, see Fig.13The rotor 2 includes a rotor body 21, a first ring edge 22 and a second ring edge extending from the rotor body 21 to the stator 3, and the second ring edge is hollowed out at equal intervals to form a plurality of rotor poles 23. In one embodiment, the control winding B 332 is a concentrated winding, and the plurality of stator poles B 331 and the control winding B 332 include a +X winding coil and a pole, a -X winding coil and a pole, a +Y winding coil and a pole, and a -Y winding coil and a pole. By increasing the current of the +X winding coil and / or reducing the current of the -X winding coil, the force applied by the +X winding coil and the pole to the rotor 2 along the -X direction can be greater than the force applied by the -X winding coil and the pole to the rotor 2 along the +X direction, and the rotor 2 moves along the -X direction of the stator 3. Conversely, the rotor 2 moves along the +X direction of the stator 3, thereby realizing active control of the rotor in the x degree of freedom. Based on the same principle, the rotor 2 can be moved along the -Y direction of the stator 3, and vice versa, the rotor 2 can be moved along the +Y direction of the stator 3, thereby realizing active control of the rotor in the y degree of freedom. It should be noted that the +X winding coil and magnetic pole, -X winding coil and magnetic pole, +Y winding coil and magnetic pole, and -Y winding coil and magnetic pole here can be a single winding coil and a single magnetic pole, or can be the resultant force generated by multiple winding coils and multiple magnetic poles.

[0065] According to the embodiment of the present disclosure, see Figure 8 and Fig. 9 The magnetic suspension turntable further includes a permanent magnet device 31, which can be configured as a permanent magnet ring, which is clamped between the first suspension control component 32 and the second suspension control component 33. The permanent magnet device can also be configured to include a plurality of permanent magnet components 311, which are evenly arranged in the circumferential direction, and are clamped between the first suspension control component 32 and the second suspension control component 33. The permanent magnet device 31 is configured to apply a permanent magnet bias magnetic field to the rotor 2.

[0066] According to the embodiment of the present disclosure, see Fig.14 and Fig.15, a plurality of motor slots 334 are formed on the side of each stator pole B331 facing the rotor 2, and a motor tooth 335 is formed between two adjacent motor slots 334. Preferably, a motor slot gap 333 is formed between two adjacent stator poles B331, and the motor slot gap is configured as a motor slot 334. In this way, a rotation control winding 336 for rotation control can be arranged in the motor slot 334 to realize the rotation control of the rotor 2, and the control winding B332 is arranged on the side of the rotation control winding facing away from the rotor 2. The permanent magnetic bias magnetic field generated by the permanent magnet assembly 311 is sequentially guided to the motor tooth 335 through the stator pole B331 (the iron core of the control winding), and an air gap is formed between the motor tooth 335 and the second ring edge of the rotor 2 and the rotor pole 23, thereby realizing the integrated design of motor rotation control and radial suspension control, optimizing the motor rotation control structure and the suspension control structure, and achieving the purpose of compact structure. In this embodiment, the rotation control winding is a concentrated winding, wherein the motor teeth are configured as the core of the concentrated winding, and the concentrated winding is wound on the corresponding motor teeth. In another embodiment, the rotation control winding can also be designed as a distributed winding.

[0067] In the above embodiments, the rotor 2 is formed of a magnetic material, and examples of the magnetic material include but are not limited to permanent magnetic materials or ferromagnetic materials. Furthermore, for example, the ferromagnetic material is a soft magnetic material whose magnetic permeability is much greater than the magnetic permeability of a vacuum, and examples thereof include but are not limited to iron, cobalt, nickel and alloys thereof, carbon steel, silicon steel, and electrical pure iron. Examples of permanent magnetic materials include but are not limited to samarium cobalt, neodymium iron boron, and ferrite.

[0068] In the above embodiments, for the convenience of explanation, the first stator substrate 3210 and the second stator substrate 3220 are described as two parts, which are convenient for processing and manufacturing, but not limited to this. In other embodiments, the first stator substrate and the second stator substrate can also be an integral structure. In this case, the first stator pole 3211 and the second stator pole 3221 are both formed on the stator substrate of the integral structure. In the above embodiments, the stator pole and the stator substrate are described as two parts, but not limited to this. In other embodiments, the stator pole and the stator substrate can be integrally formed. For example, the stator pole and the stator substrate, the magnetizer, the magnetic core and the yoke are all formed of magnetic conductive materials. Further, for example, the magnetic conductive material is a ferromagnetic material; the ferromagnetic material is, for example, a soft magnetic material whose magnetic permeability is much greater than the magnetic permeability of a vacuum, and its examples include but are not limited to iron, cobalt, nickel and its alloys, carbon steel, silicon steel, and electrical pure iron.

[0069] In the above embodiments, the permanent magnet assembly is used to provide a permanent magnet bias magnetic field, and multiple permanent magnet assemblies are equidistantly surrounded by the periphery of the rotor. In one embodiment, each permanent magnet assembly includes at least one axially magnetized permanent magnet. That is, the permanent magnet assembly at each position around the rotor can be a permanent magnet, or two or more permanent magnets. Each permanent magnet axially magnetized can provide bias flux for the first and second stator poles and stator pole B at the same time. Examples of permanent magnets include but are not limited to samarium cobalt, neodymium iron boron, and ferrite.

[0070] According to the disclosed embodiments, the magnetic levitation turntable of the present invention is applied to semiconductor manufacturing, for example, rapid thermal processing and other wafer processing in semiconductor manufacturing, such as chemical vapor deposition, thermal processing, ion implantation and other technical doping. The present invention integrates the axial radial displacement sensor in the stator. With the help of the first ring edge of the rotor, the axial radial displacement sensor can detect the position information of at least one degree of freedom direction (axial or / and radial) of the rotor through the cavity wall of the semiconductor processing equipment, thereby realizing the organic combination of rotor position detection and stator structure. The embodiment of the present invention does not need to make through holes on the vacuum cavity and use fluororubber sealing rings, nor does it need to replace the sealing rings, which solves the problems of recalibration and installation errors after assembling the sensor, can better meet the ultra-clean and high-temperature environment requirements of semiconductor processing equipment, and can solve the problem of messy cable connections of multiple displacement sensors.

[0071] In one embodiment, the magnetic levitation turntable of the disclosed embodiment also includes a carrier, and the rotor 2 supports and positions the carrier through a plurality of support columns 24. The stator 3 drives the rotor 2 and the carrier to rotate and suspend, thereby realizing individual processing of the wafers supported on the carrier.

[0072] Fig.16 The structure diagram of another embodiment of the central axis radial displacement sensor of the present invention is as follows Figure 1 ; Fig.17 The structure diagram of another embodiment of the central axis radial displacement sensor of the present invention is as follows Figure 2 .

[0073] See also Fig.16 and Fig.17The axial radial sensor in this embodiment includes most of the features of the above embodiments, for example, it includes two magnetic conductors 1, each of which includes a magnetic core 11 and a magnetic yoke 12, and a first gap 13 is provided between the magnetic core and the magnetic yoke; the two magnetic cores are arranged axially along the rotor 2, and an induction coil L2 is sleeved outside each magnetic core, and an excitation coil L1 is sleeved outside the two magnetic cores, and the excitation coil is configured to detect the radial displacement of the rotor, and the excitation magnetic field of the excitation coil constitutes a first magnetic circuit through the magnetic core, the rotor and the magnetic yoke, and the two induction coils are configured to detect the axial displacement of the rotor, and the induced magnetic field of each induction coil constitutes a second magnetic circuit through the magnetic core, the rotor and the magnetic yoke. The difference is that in this embodiment, the two magnetic conductors are an integrally formed magnetic tank structure, the cross section of the magnetic yoke is a square ring or a circular ring, and the cross section of the magnetic core is a square.

[0074] In this embodiment, the overall shape of the axial radial displacement sensor is a magnetic tank structure, which is convenient for separate configuration and use. For example, the independently packaged axial radial sensor can be used on the outer shell of a magnetic bearing, a magnetic suspension turntable, or a magnetic suspension pump that needs to measure axial displacement.

[0075] According to the embodiment of the present disclosure, the axial radial displacement sensor further includes a housing 15, a housing 15 having a housing space formed therein, and a magnetic tank structure installed in the housing space and close to one end of the housing 15. In this way, the sensor probe is formed by encapsulating the housing, and the detection end of the sensor probe can be closed or not, and is used as an inductive sensor, which can measure both axial and radial displacements.

[0076] Fig.18 It is a structural schematic diagram of an embodiment of an axial measurement circuit in a displacement measurement circuit of the present invention; Fig.19 It is a structural schematic diagram of another embodiment of the axial measurement circuit in the displacement measurement circuit of the present invention; Fig. 20 It is a structural schematic diagram of a radial measurement circuit in a displacement measurement circuit in the present invention.

[0077] See also Fig.18 , Fig.19 and Fig. 20The present invention also proposes a displacement measurement circuit, including a radial measurement circuit for measuring radial displacement and an axial measurement circuit for measuring axial displacement. The radial measurement circuit includes the excitation coil of the above-mentioned axial radial displacement sensor, and the axial measurement circuit includes the two induction coils of the above-mentioned axial radial displacement sensor. The excitation coil of the axial radial displacement sensor is connected to the radial measurement circuit, and the radial displacement can be detected according to the change of the magnetic field of the excitation coil. Similarly, the two induction coils are connected to the axial displacement measurement circuit, and the axial displacement can be detected according to the change of the magnetic field of the two induction coils. The radial measurement circuit and the axial measurement circuit also include converting, amplifying, and filtering the electrical signal to form a standard signal that can be recognized and used by subsequent processing units (such as data acquisition systems, controllers, displays, or recording devices).

[0078] According to the embodiment of the present disclosure, see Fig.18 , the radial measurement circuit also includes a first amplifier A1, a first resistor R1 and an excitation source AC, one end of the excitation coil L1 is electrically connected to one end of the excitation source AC, the other end of the excitation coil L1 is electrically connected to the first resistor R1 and an input end of the first amplifier A1, and the other end of the first resistor R1 is electrically connected to the other end of the excitation source AC and the other input end of the first amplifier A1 and is grounded. Among them, the excitation source is used to apply an alternating voltage or alternating current to the excitation coil to generate an alternating magnetic field. For example, the excitation source provides a constant voltage excitation. On the one hand, the magnetomotive force of the alternating magnetic field changes with the radial displacement of the rotor. The first resistor and the first amplifier are set to output and amplify the change in the magnetomotive force of the excitation coil for use as a measurement of the radial displacement. On the other hand, this alternating magnetic field passes through the induction coil and can generate an induced electromotive force in the induction coil. The induced electromotive force of the two induction coils changes with the axial displacement of the rotor and can be used as a measurement of the axial displacement. The first resistor is used as a current sampling resistor, and its resistance is much smaller than the impedance of the inductance of the excitation coil for current sampling. The first amplifier can set the gain according to the requirements, such as the operational amplifier gain setting resistor voltage divider ratio, feedback, and amplify the signal to the required amplitude. The first amplifier is configured as input high impedance.

[0079] According to the embodiment of the present disclosure, see Fig.19The displacement measurement circuit includes two radial measurement circuits for measuring radial displacement, one radial measurement circuit includes an excitation coil of an axial radial displacement sensor, denoted as a first measurement coil L1', and the other radial measurement circuit includes an excitation coil of another axial radial displacement sensor, denoted as a second measurement coil L1", and the output ends of the two radial measurement circuits are electrically connected to the in-phase input end and the inverting input end of the first differential amplifier A2, respectively. Among them, the two radial measurement circuits also include a first amplifier A1, a first resistor R1 and an excitation source AC, one end of the excitation coil L1 is electrically connected to one end of the excitation source AC, the other end of the excitation coil L1 is electrically connected to the first resistor R1 and one input end of the first amplifier A1, and the other end of the first resistor R1 is electrically connected to the other end of the excitation source AC and the other input end of the first amplifier A1 and grounded. In this way, the excitation coils of two different axial radial displacement sensors are combined in one measurement circuit to realize the differential output of the displacement measurement circuit, thereby reducing the influence of noise, improving the measurement accuracy, eliminating the influence of common-mode signals, and improving the reliability of the sensor output signal. For example, the two axial radial displacement sensors are arranged symmetrically along the radial direction of the rotor.

[0080] According to the embodiment of the present disclosure, see Fig. 20 , the two induction coils of the displacement measurement circuit are recorded as the first detection coil L2' and the second detection coil L3'. The axial measurement circuit also includes a second differential amplifier A3. One end (opposite end) of the first detection coil L2' is electrically connected to one end (opposite end) of the second detection coil L3' and grounded. The other end (same end) of the first detection coil is electrically connected to the in-phase input end of the second differential amplifier, and the other end (same end) of the second detection coil is electrically connected to the inverting input end of the second differential amplifier. In this way, the two induction coils of the axial radial displacement sensor are directly electrically connected to the differential amplifier, and the induced magnetomotive force on the two induction coils is output as a difference, which can be used for the axial displacement detection of the rotor. The circuit is simple, low cost, and has good sensitivity. The differential output voltage can be obtained by phase-sensitive detection and filtering to obtain a DC output.

[0081] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A shaft radial displacement sensor, characterized in that: It comprises two magnetic conductors, each of which comprises a magnetic core and a magnetic yoke, and a first gap is formed between the magnetic core and the magnetic yoke; the two magnetic cores are arranged along the axial direction of the rotor, each of which is provided with an induction coil, and the two magnetic cores are provided with an excitation coil together, the excitation coil is configured to detect the radial displacement of the rotor, and the excitation magnetic field of the excitation coil constitutes a first magnetic circuit through the magnetic core, the rotor and the magnetic yoke; the two induction coils are configured to detect the axial displacement of the rotor, and the induced magnetic field of each induction coil constitutes a second magnetic circuit through the magnetic core, the rotor and the magnetic yoke.

2. The shaft radial displacement sensor according to claim 1, characterized in that: The magnetic conductor also includes a magnetic matrix, and one end of the magnetic core and one end of the magnetic yoke are connected through the magnetic matrix.

3. The shaft radial displacement sensor according to claim 2, characterized in that: The cross section of the magnetic core is square, each of the magnetic conductors includes two magnetic yokes, the cross section of the magnetic yoke is square, and the two magnetic yokes are arranged on both sides of the magnetic core.

4. The shaft radial displacement sensor according to claim 3, characterized in that: The axial height of the magnetic core is the same as the axial height of the magnetic yoke, and the upper surface of the magnetic core is flush with the upper surface of the magnetic yoke. The cross-sectional area of ​​the magnetic core is 1-3 times the cross-sectional area of ​​the magnetic yoke.

5. The shaft radial displacement sensor according to claim 1, characterized in that: The excitation coil is arranged at one end of the magnetic core close to the rotor, and the induction coil is arranged at a side of the excitation coil facing away from the rotor.

6. The axial radial displacement sensor according to claim 1, characterized in that: A sum of a first distance between the rotor and the magnetic core and a second distance between the rotor and the magnetic yoke is less than or equal to a third distance between the magnetic core and the magnetic yoke.

7. The axial radial displacement sensor according to claim 1, characterized in that: An auxiliary coil is sleeved on the yoke of each of the magnetic conductors. The auxiliary coil is connected in series with the induction coil on the magnetic core. The magnetic field generated by the induction coil on the magnetic core and the magnetic field generated by the auxiliary coil on the yoke are superimposed and enhanced.

8. The shaft radial displacement sensor according to claim 4, characterized in that: The rotor includes a rotor body and a first ring edge formed on the rotor body, wherein the axial height of the first ring edge is between the upper surface of one of the magnetic cores and the lower surface of the other magnetic core, and the range of axial movement of the first ring edge is: the upper surface of the first ring edge does not exceed the upper surface of one of the magnetic cores, and the lower surface of the first ring edge does not exceed the lower surface of the other magnetic core.

9. The shaft radial displacement sensor according to claim 2, characterized in that: The two magnetic conductors are an integrally formed magnetic tank structure, the cross section of the magnetic yoke is in the shape of a square ring or a circular ring, and the cross section of the magnetic core is in the shape of a square.

10. The shaft radial displacement sensor according to claim 9, characterized in that: It also includes a shell, in which a containing space is formed, and the magnetic tank structure is installed in the containing space and close to one end of the shell.

11. A displacement measurement circuit, characterized in that: It comprises a radial measurement circuit for measuring radial displacement and an axial measurement circuit for measuring axial displacement, wherein the radial measurement circuit comprises an excitation coil of the axial radial displacement sensor according to any one of claims 1 to 10, and the axial measurement circuit comprises two induction coils of the axial radial displacement sensor according to any one of claims 1 to 10.

12. The displacement measurement circuit according to claim 11, characterized in that: The radial measurement circuit includes a first amplifier, a first resistor and an excitation source, one end of the excitation coil is electrically connected to one end of the excitation source, the other end of the excitation coil is electrically connected to the first resistor and an input end of the first amplifier, and the other end of the first resistor is electrically connected to the other end of the excitation source and the other input end of the first amplifier and is grounded.

13. The displacement measurement circuit according to claim 12, characterized in that: It includes two radial measurement circuits for measuring radial displacement, one of the radial measurement circuits includes an excitation coil of the axial radial displacement sensor, denoted as the first measurement coil, and the other radial measurement circuit includes another excitation coil of the axial radial displacement sensor, denoted as the second measurement coil, and the output ends of the two radial measurement circuits are electrically connected to the in-phase input end and the inverting input end of the first differential amplifier, respectively.

14. The displacement measurement circuit according to claim 11, characterized in that: The two induction coils are recorded as a first detection coil and a second detection coil. The axial measurement circuit also includes a second differential amplifier. One end of the first detection coil is electrically connected to one end of the second detection coil and is grounded. The other end of the first detection coil is electrically connected to the non-inverting input end of the second differential amplifier. The other end of the second detection coil is electrically connected to the inverting input end of the second differential amplifier.

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