A measuring device and method for rotating parts

Abstract

The present invention discloses a measuring device and method for a rotating part, the measuring device comprising: a stator, the interior of which is in a cavity shape; a rotor, which is arranged inside the stator and has a spacing with the stator, and the rotor and the stator are not connected to each other; a power supply, which applies voltage to different paired positions of the rotor and the stator that are not connected to each other, so that two or more parallel capacitors are formed between the rotor and the stator; a capacitance value measurement system, which is arranged on the rotor or the stator, and is used to measure the capacitance value of the rotor or the stator, and use the small change of the measured capacitance value to calculate and obtain the small change of the distance between the rotor and the stator. The present invention uses a non-contact parallel capacitor structure and its measurement circuit to accurately measure the small radial displacement change and geometric change of the rotor, and obtain the change of the temperature difference between the rotor and the stator, so as to monitor the reliability and real-time status of the operation of the rotating part.

Description

Technical Field

[0001] The invention relates to the technical field of molecular pumps, and in particular to a measuring device and method for a rotating component. Background Art

[0002] This section merely provides background information related to the present disclosure and may not constitute prior art.

[0003] Molecular pumps can achieve high vacuum and ultra-high vacuum, and are widely used in the semiconductor industry, lighting industry, solar energy industry, optical components, and thin film industry. Turbomolecular pumps use high-speed rotating blades and stationary fixed blades to cooperate with each other. In the molecular flow area, gas molecules collide with the high-speed rotating blade surface, and the momentum is transferred to the gas molecules, so that some gas molecules obtain tangential velocity in the direction of motion of the rigid body surface, produce directional compression, flow and are discharged from the pump, thereby achieving the purpose of pumping gas. Figure 1 and Figure 2 shown.

[0004] It is difficult to detect the radial displacement change of the existing molecular pump rotor during high-speed rotation. The radial displacement change of the molecular pump rotor will affect the reliability of the molecular pump. With the increasing process load requirements of the application industry, the reliability and real-time status monitoring of the molecular pump rotor operation are becoming more and more important. Therefore, it is very important to develop a device that can measure the position of the molecular pump rotor in real time. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect that it is difficult to detect the radial displacement change of the rotor of the molecular pump during high-speed rotation of the rotor of the existing molecular pump, thereby providing a measuring device and method for a rotating part.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A measuring device for a rotating component, used for measuring the position of the rotating component, the measuring device comprising:

[0008] The stator has a hollow interior;

[0009] A rotor is arranged inside the stator and has a distance from the stator, and the rotor and the stator are not connected to each other;

[0010] A power supply for applying voltage to different pairs of positions of the rotor and the stator that are not conductive to each other, so that two parallel capacitors are formed between the rotor and the stator;

[0011] The capacitance value measurement system is arranged on the rotor or the stator, and is used to measure the capacitance value of the rotor or the stator, and use the small changes in the measured capacitance value to calculate and obtain the small changes in the distance between the rotor and the stator and the yaw direction and rotation speed of the rotor.

[0012] Further optimizing the technical solution, the capacitance value measurement system includes:

[0013] At least one pair of measuring electrodes are symmetrically arranged on the rotor or the stator; the measuring electrodes are driven by a high-frequency voltage or current, and the test signal thereof is a voltage signal or a current signal;

[0014] The detection sensor corresponds to the position of the measuring electrode and is used to detect the charging time of the measuring electrode.

[0015] According to a further optimized technical solution, the measuring electrode is installed inside the rotor or outside the rotor or on the radial diameter of the main shaft or on the axial end face of the main shaft.

[0016] To further optimize the technical solution, the measuring device is applied to the position measurement of the molecular pump rotor and / or the temperature measurement of the molecular pump rotor.

[0017] A method for measuring a rotating component, used for measuring the position of the rotating component, the method is based on the measuring device for the rotating component, and comprises the following steps:

[0018] Applying voltage to different pairs of positions of the rotor and the stator that are not conductive to each other, so that two or more parallel capacitors are formed between the rotor and the stator;

[0019] The capacitance value of the rotor or the stator is measured by a capacitance measurement system, and the slight change of the measured capacitance value is used to calculate and obtain the slight change of the distance between the rotor and the stator and the yaw direction and rotation speed of the rotor.

[0020] Further optimizing the technical solution, the method of calculating and obtaining the slight change in the distance between the rotor and the stator by using the slight change in the measured capacitance value is based on a capacitance formula; the capacitance formula is:

[0021]

[0022] Where: C is the capacitance between the rotor and the stator; Q is the charge; U A is the voltage value of the rotor; U B is the stator voltage value; ε r is a constant; S is the area facing the capacitor plates; k is the electrostatic force constant; d is the distance between the capacitor plates.

[0023] To further optimize the technical solution, the method for measuring the capacitance value is:

[0024] The linear relationship between capacitance and voltage is used to determine the capacitance by measuring the charging time of the capacitor.

[0025] Further optimizing the technical solution, the use of the measured slight change in the capacitance value to calculate and obtain the slight change in the distance between the rotor and the stator is based on the following formula:

[0026]

[0027] Where: ΔC is the capacitance value between the rotor and the stator, and Δd is the small change in the distance between the rotor and the stator.

[0028] To further optimize the technical solution, the measuring method is also used to measure the temperature of the rotating parts, and the change of the temperature difference between the rotor and the stator is obtained by a slight change in the distance between the rotor and the stator and based on the thermal expansion and contraction effect; the thermal expansion and contraction formula of the thermal expansion and contraction effect is:

[0029] Δd=αdΔt

[0030] Where: Δt is the small change in the temperature difference between the rotor and the stator, α is the linear expansion coefficient, and d is the original distance between the rotor and the stator;

[0031] Through the capacitance formula and the thermal expansion and contraction formula, the relationship between the capacitance change and the temperature difference change between the rotor and the stator is derived:

[0032]

[0033] Where: ΔC is the capacitance value between the rotor and the stator;

[0034] The temperature difference of the rotor relative to the stator is calculated by the relationship between the capacitance change and the temperature difference change between the rotor and the stator.

[0035] Further optimization of the technical solution also includes methods to eliminate system deviations:

[0036] Eliminate rotor speed variations through calibration;

[0037] And / or obtain the change of the geometric profile within the circumference of the rotor through the change of the rotational speed of the rotor, and eliminate the change of the geometric profile of the rotor through calibration.

[0038] The technical solution of the present invention has the following advantages:

[0039] 1. The present invention provides a measuring device for a rotating component, which utilizes a non-contact parallel capacitor structure and its measuring circuit to accurately measure tiny radial displacement changes and geometric changes of the rotor, as well as changes in the temperature difference between the rotor and the stator, so as to monitor the reliability and real-time status of the operation of the rotating component.

[0040] 2. The present invention provides a measuring device for a rotating part. When a capacitor is connected to a power supply, the capacitor absorbs charge from the power supply and stores it between the two plates (stator and rotor) of the capacitor. The measuring electrode is connected to the rotor or stator. The detection sensor is arranged in a non-contact corresponding manner with the measuring electrode, and can detect the charging time on the rotor or stator, and then obtain the capacitance values ​​of the two capacitors.

[0041] 3. The present invention provides a measuring device for a rotating part, wherein the measuring electrode is installed inside the rotor or outside the rotor or on the radial diameter of the main shaft or on the stator on the axial end face of the main shaft. The detection sensor is non-contact with the measuring electrode and can accurately detect the charging time on the measuring electrode.

[0042] 4. The present invention provides a method for measuring a rotating part, in which voltage is applied to different paired positions of the rotor and the stator that are not conductive to each other. Two or more parallel capacitors are formed between the rotor and the stator as two conductors. The slight changes in the capacitance value on the rotor or stator are measured by a capacitance measurement system to obtain the slight changes in the time gap between the rotor and the stator. The structure and implementation method are simple and effective, and the measurement accuracy can be guaranteed.

[0043] 5. The present invention provides a method for measuring a rotating part. The relationship between the change in capacitance and the change in temperature difference between the rotor and the stator is derived through the capacitance formula and the thermal expansion and contraction formula. The temperature difference between the rotor and the stator is calculated through the relationship between the change in capacitance and the temperature difference between the rotor and the stator, thereby making it very convenient to measure the temperature difference with high measurement accuracy.

[0044] 6. The present invention provides a method for measuring a rotating component, which also includes a method for eliminating system deviations, and can eliminate system deviations, thereby making the measurement accuracy of the rotor temperature higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1It is a schematic diagram of the structure of a molecular pump in the prior art;

[0047] Figure 2 It is a schematic diagram of a molecular pump in the prior art when pumping gas;

[0048] Figure 3 It is a schematic diagram of the internal structure of the molecular pump;

[0049] Figure 4 It is a schematic structural diagram of a measuring electrode in a measuring device for a rotating component provided by the present invention when it is installed on the inner side of the wall thickness in the radial direction of a turbine rotor;

[0050] Figure 5 It is a schematic structural diagram of a measuring electrode in a measuring device for a rotating component provided by the present invention when it is installed on the radial diameter of a main shaft;

[0051] Figure 6 The measuring electrode in the measuring device of a rotating component provided by the present invention is installed on the stator which is at the axial end face of the main shaft;

[0052] Figure 7 It is a schematic diagram of the structure of a parallel plate capacitor;

[0053] Figure 8 It is a schematic diagram of the structure when two capacitors connected in parallel are formed between the rotor and the stator of the present invention.

[0054] Reference numerals:

[0055] 1. Rotor, 11. Moving blades, 2. Stator, 21. Fixed blades, 3. Bearings, 4. Motor, 5. Main shaft, 6. Pump body, 7. Air inlet, 8. Capacitor, 81. First electrode plate, 82. Second electrode plate, 83. Insulating medium, 9. Measuring electrode, 10. Detection sensor. DETAILED DESCRIPTION

[0056] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0057] In the description of the present invention, it should be noted that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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 limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] It should be noted that the present invention illustrates the measuring device and method of the rotating part of the present invention through a molecular pump, which is only a preferred embodiment, and does not limit the protection scope of the measuring device and method of the rotating part. For example, the measuring device and method of the rotating part of the present invention can also be applied to other types of vacuum pumps, and such adjustment also falls within the protection scope of the measuring device and method of the rotating part of the present invention.

[0061] A molecular pump is a vacuum pump that uses a high-speed rotating rotor to transfer momentum to gas molecules, so that they can obtain a directional speed, and then be compressed and driven to the exhaust port to be pumped away by the front stage. With the increasing process load requirements of the application industry, the reliability of the molecular pump rotor operation and real-time status monitoring are becoming more and more important, especially the non-contact real-time monitoring of the actual temperature of the turbine rotor.

[0062] To this end, the present invention detects the position, temperature and rotation speed of the molecular pump rotor in real time, and then monitors the real-time state of the molecular pump, which can meet the process load requirements.

[0063] The specific embodiments of the present invention are described in detail below in conjunction with a measuring device for a rotating component according to the first aspect of the present invention and a measuring method for a rotating component according to the second aspect of the present invention.

[0064] Example 1

[0065] like Figures 4 to 8As shown, this embodiment discloses a measuring device for a rotating component, which is used to measure the position of the rotating component. The measuring device includes a stator 2, a rotor 1, a power supply and a capacitance value measurement system.

[0066] The interior of the stator 2 is in a hollow shape.

[0067] The rotor 1 is arranged inside the stator 2 , and there is a certain distance between the rotor 1 and the stator 2 , so that the rotor 1 and the stator 2 are in a non-contact form, and the rotor 1 and the stator 2 are not conductive to each other, so that the rotor 1 and the stator 2 are insulated.

[0068] The power supply applies different voltages to two non-conductive positions on the rotor 1 and the stator 2 , and an insulating layer (which may be an air layer) is provided between the rotor 1 and the stator 2 , so that two parallel capacitors are formed between the rotor 1 and the stator 2 .

[0069] The capacitance value measurement system is arranged on the rotor 1 or the stator 2 to measure the capacitance value of the rotor 1 or the stator 2 and calculate and obtain the slight change of the distance between the rotor 1 and the stator 2 by using the slight change of the measured capacitance value.

[0070] The measuring device for the rotating component utilizes a non-contact parallel capacitor structure and a measuring circuit thereof to accurately measure minute radial displacement changes and geometric changes of the rotor, and monitor the operating reliability and real-time status of the rotating component.

[0071] In some embodiments, the measuring device is used to measure the position of the molecular pump rotor and / or the temperature of the molecular pump rotor. The molecular pump includes a turbine rotor, a turbine stator, a pumping structure, a motor 4, a bearing 3 (magnetic bearing, mechanical bearing, etc.), a main shaft 5, a pump body 6, etc. Figure 3 As shown. The motor 4 is connected to the turbine rotor through the main shaft 5, and the motor is used to drive the operation of the main shaft and the turbine rotor. The turbine rotor is composed of a plurality of moving blades 11, and the turbine stator is composed of a plurality of fixed blades 21. The upper part of the pump body is the air inlet 7. The turbomolecular pump cooperates with high-speed rotating moving blades and stationary fixed blades. In the molecular flow area, the gas molecules collide with the high-speed rotating blade surface, and the momentum is transferred to the gas molecules, so that some gas molecules obtain tangential velocity in the direction of movement of the rigid body surface, produce directional compression, flow and are discharged out of the pump, thereby achieving the purpose of pumping air, as shown in FIG. Figure 2 shown.

[0072] In some embodiments, the capacitance value measurement system includes a measuring electrode 9 and a detection sensor 10. The measuring electrode 9 is provided with at least one pair, which are symmetrically arranged on the rotor 1 or the stator 2. The measuring electrode 9 is driven by a high-frequency voltage or current, and its test signal is a voltage signal or a current signal. The detection sensor 10 corresponds to the position of the measuring electrode 9 and is used to detect the charging time on the measuring electrode 9.

[0073] In this embodiment, when the capacitor is connected to a power source, the capacitor absorbs charge from the power source and stores it between the two plates (stator and rotor) of the capacitor, and the measuring electrode 9 is connected to the rotor 1 or the stator 2. The detection sensor 10 is arranged in a non-contact corresponding manner to the measuring electrode 9, and can detect the charging time on the rotor 1 or the stator 2, and then obtain the capacitance values ​​of the two capacitors.

[0074] In some embodiments, the capacitor has a structure in which two measuring electrodes are arranged in parallel, and the object to be measured is arranged in parallel between the two measuring electrodes. The object to be measured can be the radius or diameter thickness of a turbine rotor, or the diameter thickness of a main shaft.

[0075] In some embodiments, the capacitance value measurement system further includes a measurement circuit, which includes a signal generating part, a measuring part, a signal amplifying and processing part, and a data processing and solving part. It is necessary to detect and calibrate the initial value at the initial and rated speed and temperature.

[0076] In some embodiments, the measuring electrode 9 is mounted inside the rotor. Figure 4 As shown, the measuring electrode 9 is installed on the inner side of the wall thickness in the radial direction of the turbine rotor. The detection sensor 10 is located directly below the measuring electrode 9 and is non-contact with the measuring electrode 9, and can accurately detect the charging time on the measuring electrode 9.

[0077] In some embodiments, the measuring electrode 9 is installed outside the rotor. The measuring electrode 9 is installed outside the wall thickness in the radial direction of the turbine rotor. The detection sensor 10 is located directly below or in the horizontal direction of the measuring electrode 9 and is non-contact with the measuring electrode 9.

[0078] In some embodiments, the measuring electrode 9 is mounted on the radial diameter of the spindle, such as Figure 5 The detection sensor 10 is located in the horizontal direction of the measuring electrode 9 and is non-contact with the measuring electrode 9 , and can accurately detect the charging time on the measuring electrode 9 .

[0079] In some embodiments, the measuring electrode 9 is mounted on the stator corresponding to the axial end face of the spindle, such as Figure 6 The detection sensor 10 is located directly below the measuring electrode 9 and is non-contact with the measuring electrode 9 , and can accurately detect the charging time on the measuring electrode 9 .

[0080] Example 2

[0081] A method for measuring a rotating component, for measuring the position of the rotating component, is provided. The method is based on the measuring device for the rotating component of embodiment 1 and comprises the following steps:

[0082] Two conductors (first plate 81 and second plate 82) close to each other, with a non-conductive insulating medium 83 sandwiched between them, constitute a capacitor 8. Figure 7 As shown. When a voltage is applied between the two plates of a capacitor, the capacitor will store charge. The capacitance of a capacitor is numerically equal to the ratio of the charge on one conductive plate to the voltage between the two plates. Taking the capacitance formula of a parallel plate capacitor as an example, as shown in the following general formula (1), it can be known that the capacitance is inversely proportional to the distance between the two conductors. Therefore, the slight change in capacitance can be measured to calculate and obtain the slight change in distance; and then the slight change in distance can be used to obtain the change in the temperature difference between the rotor and the stator based on the thermal expansion and contraction effect.

[0083]

[0084] Where: C is the capacitance between the rotor and the stator, Q is the charge, U A is the voltage value of the rotor, U B is the stator voltage, ε r is a constant, S is the area facing the capacitor plates, k is the electrostatic force constant, and d is the distance between the capacitor plates.

[0085] Therefore, when different voltages are applied to the rotor 1 and the stator 2 (i.e., the voltage values ​​of the rotor 1 and the stator 2 applied to the rotor 1 and the stator 2 are different), two parallel capacitors will be formed between the rotor and the stator as two conductors, such as Figure 8 The capacitance measurement system measures the small change of the capacitance value on the rotor 1 or stator 2 (actually two capacitors in parallel) to obtain the small change of the gap between the rotor and the stator (the two gaps are symmetrical and equal).

[0086] Two measuring electrodes 9 are symmetrically installed on the stator in the radial direction and perpendicular to the rotor to measure the capacitance values ​​of the two capacitors respectively; the electrodes are driven by high-frequency voltage or current, and the test signal can be a signal characteristic such as voltage or current. Due to the slight geometric change and displacement change of the rotor diameter, the capacitance between the rotor and the two measuring electrodes changes accordingly. Through the paired measuring electrodes and their measuring circuits, the capacitance change value with high precision and resolution can be achieved, which solves the problem of accurately measuring the slight geometric change and displacement change of the rotor diameter, and can also obtain the difference change of the rotor relative to the stator temperature.

[0087] In some embodiments, the method for measuring the capacitance value is: using the linear relationship between the capacitance value and the voltage value, the capacitance value is determined by measuring the charging time of the capacitor. For example, the capacitance value is measured using a multimeter. When the capacitor is connected to a power supply, the capacitor absorbs charge from the power supply and stores it between the two plates of the capacitor. The charging time of the capacitor depends on the size of the capacitor and the voltage of the power supply. The method for measuring the capacitance value is to connect the capacitor in parallel with the power supply and measure the charging time of the capacitor. According to the linear relationship between the capacitance value and the voltage value, the capacitance value can be determined by measuring the charging time.

[0088] The calculation and acquisition of the small change in the distance between the rotor 1 and the stator 2 using the small change in the measured capacitance value is based on the following formula:

[0089]

[0090] Where: ΔC is the capacitance value between the rotor and the stator, and Δd is the small change in the distance between the rotor and the stator.

[0091] In some embodiments, the measurement method of this embodiment is also used to measure the temperature of the rotating parts. As the rotor speed changes and the real-time temperature changes, the diameter of the rotor will change accordingly with the speed and temperature, usually in an approximately linear change. The principle of the influence of the speed is that the centrifugal force of the rotation causes the rotor to expand and deform; but in fact, since the speed measured online is kept constant at the rated speed, the expansion and deformation caused by the speed is a system deviation for the measured temperature, which can be eliminated by calibration; due to the thermal expansion and contraction effect, when the temperature difference between the rotor and the stator increases, the diameter of the rotor will also increase, as shown in equation (2). This measuring device can accurately measure the change in the rotor diameter, that is, the speed value and temperature value of the rotor are obtained by measuring the actual value of the circuit (electrical signal), and the relationship between them is an approximately square relationship and a linear relationship, respectively. The approximate linear relationship (3) can be derived from equations (1) and (2), thereby achieving the purpose of measuring the rotor speed and the temperature difference between the rotor and the stator.

[0092] Through the slight change of the distance between the rotor 1 and the stator 2, the change of the temperature difference of the rotor 1 relative to the stator 2 is obtained according to the thermal expansion and contraction effect; the thermal expansion and contraction formula of the thermal expansion and contraction effect is:

[0093] Δd=αdΔt (2)

[0094] Where: Δt is the small change in the temperature difference between the rotor and the stator, α is the linear expansion coefficient, and d is the original distance between the rotor and the stator;

[0095] Through the capacitance formula and thermal expansion and contraction formula, the relationship between the capacitance change and the temperature difference between the rotor and the stator is derived:

[0096]

[0097] Where: ΔC is the changing capacitance between the rotor and the stator.

[0098] The temperature difference of the rotor relative to the stator is calculated by the relationship between the capacitance change and the temperature difference change between the rotor and the stator.

[0099] In some embodiments, the speed change measurement method is: the capacitance value change is measured by the capacitance measurement circuit, and the rotor diameter change is calibrated and calculated through the functional relationship and the change law. Since the change of the capacitance value is approximately linear, and the speed and the diameter size are approximately square, the measured capacitance value and the rotor diameter size change are approximately square.

[0100] In some embodiments, a method for measuring geometric changes is also included: after obtaining the rotational speed change, the change in the geometric profile within the circumference of the rotor, such as the change in the ellipticity of the circumferential profile, can be obtained through signal analysis and processing.

[0101] In some embodiments, a method for eliminating system deviation is also included.

[0102] Speed ​​change: The principle of the speed influence is that the centrifugal force of rotation causes the rotor to expand and deform; however, since the speed measured online remains unchanged at the rated speed, the expansion and deformation caused by the speed is a system deviation for the measured temperature, which can be eliminated through calibration.

[0103] Geometric changes: The influence of the geometric shape is exactly the same as the change in speed with each rotation of the rotor. Therefore, the principle of the influence of speed change is the same. Since the speed measured online remains unchanged at the rated speed, the distance change shape is a systematic deviation for the measured temperature, which can be eliminated through calibration.

[0104] In some embodiments, the measurement method of this embodiment also includes a method for processing measurement factors.

[0105] 1) Since the outer contour shape of the spindle periphery in actual processing also fluctuates, it is necessary to perform signal processing on the capacitance measurement value, such as performing algorithms such as moving weighted average, to obtain a more accurate actual measurement value.

[0106] 2) Regarding the solution algorithm: For the displacement number obtained by measurement, it is necessary to use the functional relationship and algorithm to solve the two components caused by its rotation speed and temperature; for the change of the displacement signal of the rotor in one circle, it is necessary to use the algorithm to compare and solve the change of the geometric contour on its circumference.

[0107] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A measuring device for a rotating part, used for measuring the position of the rotating part, characterized in that: The measuring device is applied to the position measurement of the molecular pump rotor and the temperature measurement of the molecular pump rotor; the measuring device comprises: The stator (2) has a hollow interior; A rotor (1) is arranged inside the stator (2) and has a spacing with the stator (2), and the rotor (1) and the stator (2) are not electrically connected to each other; A power supply for applying voltage to different pairs of positions of the rotor (1) and the stator (2) that are not conductive to each other, so that a plurality of capacitors connected in parallel are formed between the rotor (1) and the stator (2); A capacitance value measurement system, arranged on the rotor (1) or the stator (2), for measuring the capacitance value of the rotor (1) or the stator (2), and using a small change in the measured capacitance value to calculate and obtain a small change in the distance between the rotor (1) and the stator (2); The measuring method of the rotating part based on the measuring device of the rotating part comprises the following steps: Applying voltage to different pairs of positions of the rotor (1) and the stator (2) that are not conductive to each other, so that a plurality of capacitors connected in parallel are formed between the rotor (1) and the stator (2); The capacitance value of the rotor (1) or the stator (2) is measured by a capacitance value measurement system, and a slight change in the measured capacitance value is used to calculate and obtain a slight change in the distance between the rotor (1) and the stator (2) and a yaw direction and a rotation speed of the rotor; The capacitance value change is measured by the capacitance measurement circuit, and the rotor diameter change is calibrated and calculated through the functional relationship and the change law, and the rotor speed change is obtained according to the rotor diameter change; The capacitance value of the rotor (1) or the stator (2) is measured by the capacitance value measurement system based on a capacitance formula; the capacitance formula is: Where: C is the capacitance between the rotor and the stator, Q is the charge, U A is the voltage value of the rotor, U B is the stator voltage, ε r is a constant, S is the area of ​​the capacitor plates, k is the electrostatic force constant, and d is the original distance between the rotor and the stator; The method of calculating and obtaining the slight change in the distance between the rotor (1) and the stator (2) by using the slight change in the measured capacitance value is based on the following formula: Where: ΔC is the capacitance value between the rotor and the stator, Δd is the small change in the distance between the rotor and the stator; The measuring method is also used to measure the temperature of the rotating component, by measuring a slight change in the distance between the rotor (1) and the stator (2), and obtaining a change in the temperature difference between the rotor (1) and the stator (2) based on the thermal expansion and contraction effect; the thermal expansion and contraction formula of the thermal expansion and contraction effect is: Where: Δt is the small change in the temperature difference between the rotor and the stator, α is the linear expansion coefficient; Through the capacitance formula and the thermal expansion and contraction formula, the relationship between the capacitance change and the temperature difference change between the rotor and the stator is derived: Where: ΔC is the capacitance value between the rotor and the stator; The temperature difference of the rotor relative to the stator is calculated by the relationship between the capacitance change and the temperature difference change between the rotor and the stator.

2. A measuring device for a rotating component according to claim 1, characterized in that: The capacitance value measurement system comprises: At least one pair of measuring electrodes (9) are symmetrically arranged on the rotor (1) or the stator (2); the measuring electrodes (9) are driven by a high-frequency voltage or current, and their test signals are voltage signals or current signals; A detection sensor (10) corresponds to the position of the measuring electrode (9) and is used to detect the charging time of the measuring electrode (9).

3. A measuring device for a rotating component according to claim 2, characterized in that: When the measuring electrode (9) is arranged on the rotor (1), the measuring electrode (9) is installed inside the rotor or outside the rotor; When the measuring electrode (9) is arranged on the stator (2), the measuring electrode (9) is mounted on the stator corresponding to the axial end face of the main shaft.

4. A measuring device for a rotating component according to claim 1, characterized in that: The method for measuring the capacitance value is: The linear relationship between capacitance and voltage is used to determine the capacitance by measuring the charging time of the capacitor.

5. A measuring device for a rotating component according to any one of claims 1 to 4, characterized in that: It also includes methods to eliminate system deviations: Eliminate rotor speed variations through calibration; And / or obtain the change of the geometric profile within the circumference of the rotor through the change of the rotational speed of the rotor, and then eliminate the change of the geometric profile of the rotor through calibration.

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