Shaft radial displacement detection device and detection method

Abstract

The application provides a shaft radial displacement detection device and a detection method. The detection device comprises a shaft surface of a measured element, the shaft surface is provided with a first inclined surface and a second inclined surface, and the first inclined surface and the second inclined surface are different in inclined angle; at least two sensors are arranged on the radial circumference of the first inclined surface in opposition, and at least two sensors are arranged on the radial circumference of the second inclined surface in opposition; and the sensors are used for outputting an electric signal based on the radial displacement of the inclined surface of the measured element. Compared with the prior art, the advantage of the application is that only the radial sensors are arranged, axial sensors are not needed, and the displacement of the measured element in the axial direction and the radial direction can be detected.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of generator rotor displacement detection, and particularly relates to a shaft radial displacement detection device and a detection method. BACKGROUND

[0002] The magnetic suspension bearing is used to suspend the rotor in the air by electromagnetic force, so that there is no mechanical contact between the rotor and the stator. The magnetic suspension rotor adopts a rotor component supported by the magnetic suspension bearing, and the magnetic suspension bearing suspends the rotor in the air by electromagnetic force, so that there is no direct contact between the rotor and the stator.

[0003] Under the prior art condition, the magnetic suspension axial displacement detection needs to install an axial displacement detection disc perpendicular to the rotor on the rotor, and the sensor measures the axial displacement of the detection disc to determine the axial displacement of the rotor. However, due to the error caused by assembly, the detection surface is not perpendicular to the rotor, which leads to measurement deviation and fluctuation. On the other hand, when the unit works for a long time, the detection disc may be relatively displaced from the rotor due to thermal expansion, which leads to the deviation of the rotor from the axial air gap center, and even directly leads to the grinding of the shaft. In addition, the additional detection disc will inevitably increase the complexity and assembly difficulty of the rotor structure, increase the axial length of the rotor, reduce the critical speed of the rotor, and affect the performance of the whole machine.

[0004] The prior art also provides a solution that measures the axial displacement of the rotor by measuring the air gap difference of the inclined surface and the non-inclined surface of the rotor by a radial sensor. The above technical solution has the following problems: 1. Affected by the linearity of the sensor, once the measurement values of the two sensors do not fall within the same linear region, a large axial displacement error will be caused; 2. The size of the single-sided air gap is not only affected by the axial displacement, but also related to whether the rotor is on the axis. Once the rotor is inclined and deviates from the axis, even if the rotor does not have axial displacement, the front and rear air gaps will change, which will cause the axial displacement measurement to deviate; 3. There is a step-like mutation point at one end of the slope in the above solution. When the sensor is close to the position, the eddy current formation area changes (from the bottom of the slope to the top of the step, as shown in FIG. 1), and the measurement value will change, which will cause the axial displacement measurement to fail, and even cause the control logic to be confused and the rotor to be ground. Figure 1

[0005] ​The prior art also provides another solution, similar to the above-mentioned solution, and the difference lies in that the patent arranges a plurality of sensor probes on a conical surface, and represents the axial displacement by summing and averaging to avoid errors caused by rotor cone movement. However, the processing of the plurality of sensor measurement values of this patent is only summing and averaging, and the influence of environmental factors on the sensor cannot be eliminated. For example, under different temperatures and electromagnetic environments, the measurement value of the eddy current sensor will drift a little, and the drift amount cannot be eliminated by only summing and averaging, resulting in a decrease in measurement accuracy; in addition, this way sets too many sensors, increasing the cost. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings in the above-mentioned technology, and to provide an axial radial displacement detection device and a detection method, which can more accurately detect the radial or axial movement displacement of the rotor.

[0007] The present application provides an axial radial displacement detection device, the axial surface of the measured element is provided with a first inclined surface and a second inclined surface, the inclination angles of the first inclined surface and the second inclined surface are different; at least two sensors are arranged on the opposite radial circumferences of the first inclined surface, and at least two sensors are arranged on the opposite radial circumferences of the second inclined surface; the sensors are used to output an electric signal based on the radial displacement of the inclined surface of the measured element.

[0008] Preferably, the axial surface of the measured element further comprises a third inclined surface and a fourth inclined surface, the first inclined surface, the second inclined surface, the third inclined surface and the fourth inclined surface all incline to the inside of the shaft; one end of the first inclined surface inclining to the inside of the shaft is connected to one end of the third inclined surface inclining to the inside of the shaft, and one end of the second inclined surface inclining to the inside of the shaft is connected to one end of the fourth inclined surface inclining to the inside of the shaft.

[0009] Preferably, the included angles between the first inclined surface, the fourth inclined surface and the axis are both 45 degrees, and the included angles between the second inclined surface, the third inclined surface and the axis are both 30 degrees.

[0010] Preferably, the sensors are at least 8, at least 4 sensors are uniformly arranged on the radial circumference where the first inclined surface and the third inclined surface intersect, and at least 4 sensors are arranged on the radial circumference where the second inclined surface and the fourth inclined surface intersect.

[0011] Preferably, it comprises an axial displacement calculation unit, which is used to calculate the axial displacement of the measured element according to the electric signal, the inclination angle of the first inclined surface and the inclination angle of the second inclined surface.

[0012] Preferably, it comprises a radial displacement calculation unit, which is used to calculate the radial displacement of the measured element according to the electric signal.

[0013] Preferably, the measured element is a rotor of a magnetic levitation bearing, and the sensor is an eddy current sensor.

[0014] The application also provides a shaft radial displacement detection method, which utilizes the detection device of any of the above technical solutions to detect the axial or radial displacement of the measured element, and specifically includes receiving the electrical signal output by the sensor based on the radial displacement of the measured element, and calculating the axial or radial displacement of the measured element according to the electrical signal, the first inclined surface inclination and the second inclined surface inclination.

[0015] Preferably, the radial displacement detection method of the measured element includes obtaining the displacement values measured by the two sensors on the opposite radial circumference of the first inclined surface or the second inclined surface, and the difference between the displacement values is the radial offset of the measured element.

[0016] Preferably, the axial displacement detection method of the measured element includes obtaining the displacement values measured by the two sensors on the opposite radial circumference of the first inclined surface, calculating the sum of the two displacement values as WFx, obtaining the displacement values measured by the two sensors on the opposite radial circumference of the second inclined surface, calculating the sum of the two displacement values as WRx, and calculating the difference between WFx and WRx to obtain the double-sided air gap difference value △W.

[0017] Preferably, the axial surface of the measured element includes a third inclined surface and a fourth inclined surface, and the first inclined surface, the second inclined surface, the third inclined surface and the fourth inclined surface are all inclined inwardly to the shaft; one end of the first inclined surface inclined inwardly to the shaft is connected to one end of the third inclined surface inclined inwardly to the shaft, and one end of the second inclined surface inclined inwardly to the shaft is connected to one end of the fourth inclined surface inclined inwardly to the shaft.

[0018] The included angle between the first inclined surface and the second inclined surface and the shaft is 45 degrees, and the length of the first inclined surface and the second inclined surface is 2H. The included angle between the third inclined surface and the fourth inclined surface and the shaft is 30 degrees, and the length of the third inclined surface and the fourth inclined surface is 2H; the axial displacement Z is calculated according to the formula or

[0019] Therefore, the application sets two inclined surfaces on the measured element to measure the shaft radial displacement, and the angles of the two inclined surfaces are different. When the measured element moves axially, the sensors on the radial circumferences of the two inclined surfaces fall on the inclined surfaces of different angles, resulting in different double-sided air gaps detected by the two inclined surfaces, which is beneficial to differential calculation to improve the axial displacement detection sensitivity and avoid the influence of the spatial angle of the measured element on the accuracy of the axial measurement value. The radial sensors are set to detect the axial displacement, and the differential calculation is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0020] ​In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be obtained from the provided drawings without creative labor.

[0021] The structures, proportions, sizes, etc. shown in the specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the conditions that the present application can be implemented, so they do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that the present application can produce, should still fall within the scope of the technical content disclosed by the present application.

[0022] Figure 1 Structure diagram of prior art axial detection device;

[0023] Figure 2 Structure diagram of the measured element of the present application;

[0024] Figure 3 Structure diagram of the axial and radial displacement detection device of the present application;

[0025] Figure 4 Structure diagram of the measured element in the radial movement of the present application;

[0026] Figure 5 Structure diagram of the measured element in the axial movement of the present application;

[0027] Figure 6 Structure diagram of the detection device side of the preferred embodiment of the present application;

[0028] Figure 7 Enlarged structure diagram of the measured element in the axial movement of the present application;

[0029] Figure 8 Flowchart of the detection method of the present application;

[0030] In the figure: measured element 1, first inclined surface 21, second inclined surface 22, third inclined surface 23, fourth inclined surface 24, sensor 3. DETAILED DESCRIPTION

[0031] The following will describe the embodiments of the present application by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0032] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two, but does not exclude the case of including at least one.

[0033] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0034] It should also be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that the product or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such product or system. Without more limitations, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the product or system including the element.

[0035] As Figures 2-3 As shown in the figure, the embodiment of the present application provides a shaft radial displacement detection device, the axial surface of the measured element 1 is provided with a first inclined surface 21 and a second inclined surface 22, the inclination angles of the first inclined surface 21 and the second inclined surface 22 are different; at least two sensors 3 are arranged on the opposite radial circumferences of the first inclined surface 21, and at least two sensors 3 are arranged on the opposite radial circumferences of the second inclined surface 22, and the sensor 3 is used to output an electrical signal based on the radial displacement of the inclined surface of the measured element.

[0036] The existing magnetic suspension bearing needs five degrees of freedom bearing coils to control the spatial displacement of the rotor and five degrees of freedom displacement sensors to detect the axial displacement of the rotor in order to ensure that the rotor can be stably suspended with high precision. Not only sensors need to be arranged in the radial direction of the rotor, but also axial detection discs with multiple eddy current sensors need to be arranged in the axial direction to detect the axial displacement. The axial displacement detection disc and the axial sensor are removed in the application, and only at least four radial sensors are used to complete the five degrees of freedom displacement measurement of the rotor, thereby reducing the number of sensors and the cost.

[0037] As shown in Figures 2-3 Preferably, the axial surface of the measured element 1 in the embodiment of the application further comprises a third inclined surface 23 and a fourth inclined surface 24, and the first inclined surface 21, the second inclined surface 22, the third inclined surface 23 and the fourth inclined surface 24 are all inclined to the inside of the shaft of the measured element 1. The end of the first inclined surface 21 inclined to the inside of the shaft is connected with the end of the third inclined surface 23 inclined to the inside of the shaft, and the end of the second inclined surface 22 inclined to the inside of the shaft is connected with the end of the fourth inclined surface 23 inclined to the inside of the shaft. That is, the first inclined surface 21 and the third inclined surface 23 form a first groove with a smooth edge transition on the measured element 1, and the second inclined surface 22 and the fourth inclined surface 24 also form a second groove with a smooth edge transition on the measured element 1. The first groove and the second groove are the same in shape and structure and are symmetrical.

[0038] As shown in the prior art, Figure 1 The step-shaped mutation point exists at one end of the slope, and when the sensor 3 approaches the position, the eddy current forming area changes (from the bottom of the slope to the top of the step, as shown in Figure 1 The measurement value will change, which leads to the failure of the axial displacement measurement, and in severe cases, it will also cause the control logic to be chaotic and the rotor (measured element) to be worn. The groove is composed of two inclined surfaces, and the transition is smoother, which will not cause mutation and will avoid the serious influence caused by the mutation of the measurement value in the prior art, and it is also more convenient to process.

[0039] As shown in Figures 2-3 Preferably, the angles between the first inclined surface 21, the second inclined surface 22, the third inclined surface 23 and the fourth inclined surface 24 and the shaft line in the embodiment of the application can be arbitrarily selected. In order to be more conducive to manufacturing and processing, the preferred angle selection is that the angles between the first inclined surface 21 and the fourth inclined surface 24 and the shaft line are both 45 degrees, and the angles between the second inclined surface 22 and the third inclined surface 23 and the shaft line are both 30 degrees. The angles can be adjusted according to the needs in actual production.

[0040] Further preferably, in order to measure and calculate the result accurately and conveniently, the sensor 3 has at least 8, at least 4 of which are evenly arranged on the radial circumference where the first inclined surface 21 intersects with the third inclined surface 23, and at least 4 of which are arranged on the radial circumference where the second inclined surface 22 intersects with the fourth inclined surface 24. The sensors are arranged on the radial circumference where the inclined surfaces intersect, so that the initial detection values of the 8 sensors are all the same, which makes it more convenient to calculate the radial or axial movement of the measured element.

[0041] Preferably, the application comprises an axial displacement calculation unit for calculating the axial displacement of the measured element according to the electrical signal, the inclination angle of the first inclined surface 21, and the inclination angle of the second inclined surface 22; and / or a radial displacement calculation unit for calculating the radial displacement of the measured element according to the electrical signal.

[0042] Preferably, in the implementation of the application, the measured element 1 is a rotor of a magnetic suspension bearing, and the sensor 3 is an eddy current sensor, which can measure the distance between the measured metal conductor and the surface of the probe statically and dynamically, with non-contact, high linearity, and high resolution.

[0043] The embodiment of the application also describes in detail a method for detecting the radial displacement of a shaft, which utilizes the detection device of any of the above embodiments to detect the axial or radial displacement of the measured element, specifically including receiving the electrical signal output by the sensor 3 based on the radial displacement of the measured element 1, and calculating the axial or radial displacement of the measured element 1 according to the electrical signal, the inclination angle of the first inclined surface, and the inclination angle of the second inclined surface.

[0044] The specific calculation and execution steps include obtaining the electrical signal of the sensor 3, and respectively calculating the radial displacement of the measured element and the axial displacement of the measured element. In calculating the radial displacement, the electrical signals of the two sensors 3 opposite to the same degree of freedom of the measured element 1 are received, so as to obtain the sizes of the radial double-side air gaps at both ends, calculate the difference between the two air gaps, and output the radial displacement of the degree of freedom.

[0045] In calculating the axial displacement, the sizes of the front and rear radial double-side air gaps are obtained through the electrical signals of the sensors 3, the difference between the front and rear radial double-side air gaps is calculated, and the radial displacement of the degree of freedom is output.

[0046] For example, eight sensors 3 are arranged on the first inclined surface 21 and the third inclined surface 23, and four sensors 3 are arranged on the second inclined surface 22 and the fourth inclined surface 24. Figure 6 .

[0047] As shown in Figure 4 , preferably, the radial displacement of the measured element 1 is obtained by the differential output of two sensors, and the radial displacement detection method of the measured element 1 specifically includes obtaining the displacement values measured by the two opposite sensors on the radial circumference of the first inclined surface 21 or the second inclined surface 22, and the difference between the displacement values is the radial displacement of the measured element. For example, the detection data values of the sensors FX1 and FX2 are used to determine the radial displacement offset, when the measured element 1 is located at the center reference position of the air gap, the displacement values fx1 and fx2 measured by the sensors FX1 and FX2 are equal, and the radial displacement offset △Fx = fx1-fx2 = 0, that is, the measured element 1 does not have radial displacement. When the measured element 1 has radial displacement, the detection values of the two sensors change, the measurement value of the sensor FX1 is fx1', the measurement value of the sensor FX2 is fx2', fx1' is not equal to fx2', and the offset △Fx = fx1'-fx2' is not zero. Through such a differential measurement method, the radial displacement △Fx of the measured element 1 from the center of the air gap can be accurately detected.

[0048] As shown in Figures 5-7 , preferably, the axial displacement of the measured element 1 of the present application is calculated by the difference between the front and rear double air gaps, and the radial double air gap can be obtained by adding the measurement values of the two opposite radial sensors. The axial displacement detection method of the measured element includes obtaining the displacement values measured by the two opposite sensors on the radial circumference of the first inclined surface, calculating the sum of the two displacement values as WFX; obtaining the displacement values measured by the two opposite sensors on the radial circumference of the second inclined surface, calculating the sum of the two displacement values as WRX; and calculating the difference between WFX and WRX to obtain the double air gap difference △W.

[0049] The double-sided air gap WFX corresponding to the sensors FX1 and FX2 is equal to fx1 + fx2, where fx1 is the linear distance between the probe surface and the measured element 1 measured by the sensor FX1, and fx2 is the linear distance between the probe surface and the measured element 1 measured by the sensor FX2. The displacement sensor with four degrees of freedom in the radial direction can measure four sets of double-sided air gaps, namely WFX, WFY, WRX and WRY. Specifically, WFY = fy1 + fy2, WRX = rx1 + rx2, and WRY = ry1 + ry2, where fy1 is the linear distance between the probe surface and the measured element 1 measured by the sensor FY1, fy2 is the linear distance between the probe surface and the measured element 1 measured by the sensor FY2, rx1 is the linear distance between the probe surface and the measured element 1 measured by the sensor RX1, rx2 is the linear distance between the probe surface and the measured element 1 measured by the sensor RX2, ry1 is the linear distance between the probe surface and the measured element 1 measured by the sensor RY1, and ry2 is the linear distance between the probe surface and the measured element 1 measured by the sensor RY2. The double-sided air gap difference AW can be expressed as follows:

[0050] or 2AW = (W Fx +W Fy ) - (W Rx +W Ry ), and the x direction is taken as an example, and the same applies to the other directions.

[0051] As shown in Figure 5 , Figure 7 , when the measured element 1 is located at the initial position, all the detection points in the radial direction fall on the bottom of the groove, at which time the front and rear radial double-sided air gaps are the largest and equal, i.e., the air gap difference AW = WFX - WRX = 0.

[0052] As shown in Figure 7 , when the measured element 1 is displaced axially forward, the detection point of the front radial displacement sensor falls on the 30° gentle slope, and the double-sided air gap measured by the front radial sensor gradually decreases, and the relationship between the decrease and the axial displacement Z; as shown in Figure 8 , the following formula can be used to express the case where the two conical angles are 30° and 45°, respectively:

[0053]

[0054] where fx1 is the linear distance between the probe surface and the measured element 1 measured by the sensor FX1 when the measured element 1 is in the initial state, fx1' is the linear distance between the probe surface and the measured element 1 measured by the sensor FX1 after the measured element 1 is axially displaced, and AW Fx= 2 (fx1-fx1'), where fx1-fx1' is Figure 7 the distance shown by L.

[0055] The detection point of the rear radial circumferential sensor 3 falls on a 45° steep slope, and the change in the measured value of the rear radial double-sided air gap is:

[0056]

[0057] where rx1 is the straight-line distance between the probe surface and the measured element 1 measured by the sensor RX1 when the measured element 1 is in the initial state; rx1' is the straight-line distance between the probe surface and the measured element 1 measured by the sensor RX1 after the measured element 1 moves axially; ΔW Rx = 2 (rx1-rx1').

[0058] When , the maximum axial displacement of the measured element 1 is a fixed value, and there is no angle between the front and rear radial directions, so the maximum axial double-sided gap is When Z≥H, ΔW Rx = 2H is a fixed value.

[0059] Because the change rates of the radial double-sided air gaps at the grooves on the surface of the measured element 1 are different, the air gap difference ΔW is no longer zero, and when the measured element 1 moves forward along the axial direction, the air gap difference ΔW and the axial displacement Z have the following relationship:

[0060]

[0061] Similarly, when the measured element 1 moves backward along the axial direction, the detection point of the displacement sensor 3 close to the front end of the measured element 1 falls on a 45° steep slope, and the sensor 3 close to the rear end of the measured element 1 falls on a 30° gentle slope, and at this time, the air gap difference ΔW and the axial displacement Z (negative when moving backward) have the following relationship:

[0062]

[0063] Therefore, regardless of whether the measured element 1 moves forward or backward along the axial direction, the air gap difference ΔW between the front and rear radial double-sided air gaps can be measured by the sensors arranged on the radial circumference, and the axial displacement Z of the rotor can be obtained by the value of ΔW. In summary, the axial displacement of the rotor can be measured by only the radial displacement sensors, and the rotor does not need to be additionally provided with an axial detection disc, which simplifies the structure of the rotor, shortens the axial length of the rotor, and improves the overall performance.

[0064] The exemplary embodiments of the present disclosure are specifically shown and described above. It should be understood that the present disclosure is not limited to the detailed structure, arrangement or implementation method described herein; on the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.

Claims

1. A shaft radial displacement detection device, characterized by: The axial surface of the measured element is provided with a first inclined surface and a second inclined surface, the inclination angles of the first inclined surface and the second inclined surface are different; at least two sensors are arranged on the radial circumference of the first inclined surface in opposition, and at least two sensors are arranged on the radial circumference of the second inclined surface in opposition; the sensors are used to output electrical signals based on the radial displacement of the inclined surface of the measured element; The axial surface of the measured element further comprises a third inclined surface and a fourth inclined surface, the first inclined surface, the second inclined surface, the third inclined surface and the fourth inclined surface all incline towards the inside of the shaft; one end of the first inclined surface inclining towards the inside of the shaft is connected to one end of the third inclined surface inclining towards the inside of the shaft, and one end of the second inclined surface inclining towards the inside of the shaft is connected to one end of the fourth inclined surface inclining towards the inside of the shaft; The included angles of the first inclined surface and the fourth inclined surface with the axis are equal, and the range is between 0-90 degrees, the included angles of the second inclined surface and the third inclined surface with the axis are equal, and the range is between 0-90 degrees; The sensors are at least eight, and at least four of the sensors are uniformly arranged on the radial circumference where the first inclined surface and the third inclined surface intersect, and at least four of the sensors are arranged on the radial circumference where the second inclined surface and the fourth inclined surface intersect.

2. The detection device of claim 1, wherein: The included angles of the first inclined surface and the fourth inclined surface with the axis are 30 degrees, and the included angles of the second inclined surface and the third inclined surface with the axis are 45 degrees.

3. The detection device of claim 1, wherein: The displacement calculation unit is used to calculate the axial displacement of the measured element according to the electrical signals, the inclination angle of the first inclined surface and the inclination angle of the second inclined surface; and / or is used to calculate the radial displacement of the measured element according to the electrical signals.

4. A method of detecting radial displacement of a shaft, characterized by: The detection device according to any one of claims 1-3 is used to detect the axial or radial displacement of the measured element, specifically including receiving the electrical signals output by the sensors based on the radial displacement of the measured element, and calculating the axial or radial displacement of the measured element according to the electrical signals, the inclination angle of the first inclined surface and the inclination angle of the second inclined surface.

5. The method of claim 4, wherein: The radial displacement detection method of the measured element includes obtaining the displacement values measured by two sensors arranged in opposition on the radial circumference of the first inclined surface or the second inclined surface, and the difference between the displacement values is the offset of the measured element in the radial direction.

6. The method of claim 4, wherein: The axial displacement detection method of the measured element includes obtaining the displacement values measured by two sensors arranged in opposition on the radial circumference of the first inclined surface, calculating the sum of the two displacement values as WFx; obtaining the displacement values measured by two sensors arranged in opposition on the radial circumference of the second inclined surface, calculating the sum of the two displacement values as WRx; and calculating the difference between WFx and WRx to obtain the double-sided air gap difference value ΔW.

7. The method of claim 4, wherein: The axial surface of the measured element comprises a third inclined surface and a fourth inclined surface, the first inclined surface, the second inclined surface, the third inclined surface and the fourth inclined surface all incline towards the inside of the shaft; one end of the first inclined surface inclining towards the inside of the shaft is connected to one end of the third inclined surface inclining towards the inside of the shaft, and one end of the second inclined surface inclining towards the inside of the shaft is connected to one end of the fourth inclined surface inclining towards the inside of the shaft; The included angle between the first inclined surface, the second inclined surface and the axis is 45 degrees and the length is The included angle between the third inclined surface, the fourth inclined surface and the axis is 30 degrees and the length is 2H; according to the formula Or Calculate the axial displacement Z.

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