JP2018115949A - Fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid machine capable of measuring temperature of a rotor by considering a case when a position variation of the rotor occurs in operation of the fluid machine.SOLUTION: A rotor 30 includes: a first measurement area 32 capable of generating a first magnetic field; and a second measurement area 34 capable of generating a second magnetic field differing from the first magnetic field. A first measurement signal and a second measurement signal outputted by a sensor 36 are variable depending on temperature of the first measurement area and the second measurement area. The first measurement signal and the second measurement signal are variable depending on a distance between the first measurement area 32 and the second measurement area 34, and the sensor 36. A processing unit 38 detects temperature of the first measurement area 32 and the second measurement area 34, and a distance between the first measurement area 32 and the second measurement area 34, and the sensor, based on both of the first measurement signal and the second measurement signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fluid machine, and more particularly to measuring the temperature or position of a rotating body in a non-contact manner during operation of the fluid machine.

  In a fluid machine that is a device that converts energy between a fluid and a machine, the temperature of the rotating body is important information for improving the reliability of the fluid machine and the durability against the fluid. When the rotating body reaches a high temperature exceeding the allowable temperature of the material of the rotating body, the strength of the rotating body decreases. When the strength of the rotating body is reduced, the rotating body may be broken by a centrifugal force acting on the rotating body. Moreover, durability (for example, corrosion resistance) with respect to a fluid changes with the temperature of a rotary body. Depending on the temperature of the rotating body, there is a difference in the deposition rate of the product deposited from the fluid onto the machine, and it may be necessary to change the replacement timing of the fluid machine depending on the temperature of the rotating body. If the temperature of the rotating body is equal to or higher than a certain temperature, the amount of the precipitated product can be reduced, and the life of the fluid machine may be extended. On the other hand, depending on the type of fluid, it may be preferable that the temperature of the rotating body is low. Therefore, it is preferable to measure the temperature of the rotating body and display the temperature or to control the rotation of the rotating body.

  Conventionally, temperature measurement using a magnetic sensor utilizing the fact that inductance changes with changes in the temperature of a rotating body has been known. However, for the magnetic sensor, the measured value of the magnetic sensor varies not only with the temperature of the rotating body but also with the distance between the rotating body and the magnetic sensor. When the variation in the distance is not taken into account, the measurement signal of the magnetic sensor causes a measurement error due to a change in the distance due to a variation in the position of the rotating body. In Japanese Patent Laid-Open No. 2015-129521, when the position of the rotating body fluctuates, the circuit characteristics of the measurement circuit are adjusted.

  However, in Japanese Unexamined Patent Application Publication No. 2015-129521, the circuit characteristics of the measurement circuit are adjusted at the manufacturing stage of the fluid machine. No consideration is given to the case where the position of the rotating body fluctuates during operation of the fluid machine.

JP2015-129521A

  One aspect of the present invention is to solve such problems, and the purpose of the present invention is to measure the temperature of the rotating body in consideration of the case where the position of the rotating body fluctuates during operation of the fluid machine. Is to provide a simple fluid machine.

In order to solve the above-described problem, in the first embodiment, a first measurement region that has a first material and can generate a first magnetic field, and a second material that is different from the first material are used. A rotating body having a second measurement region that can generate a second magnetic field different from the first magnetic field, and a position that can face the first measurement region and the second measurement region. A main body having an eddy current sensor arranged and capable of generating the first magnetic field and the second magnetic field, and the sensor detecting the first magnetic field and the second magnetic field. A processing unit for processing the output first measurement signal and the second measurement signal, wherein the first magnetic field and the second magnetic field correspond to the first measurement region and the second measurement region, respectively. By being variable depending on the temperature, the first
The measurement signal and the second measurement signal can be changed depending on the temperatures of the first measurement region and the second measurement region, and the first measurement signal and the second measurement signal are The first measurement region and the second measurement region can be changed depending on a distance between the sensor and the processing unit based on both the first measurement signal and the second measurement signal. The configuration is a fluid machine that detects the temperature of the first measurement region and the second measurement region, and the distance between the first measurement region, the second measurement region, and the sensor.

  In the present embodiment, the processing unit, based on both the first measurement signal and the second measurement signal, the temperature of the first measurement region and the second measurement region, and the first measurement region and the second measurement region. The distance between the measurement area and the sensor is detected. Since the processing unit uses two measurement signals, that is, a first measurement signal and a second measurement signal, it can detect two quantities, that is, a temperature and a distance when the temperature changes. The processing unit uses two measurement signals (first measurement signal and second measurement signal) related to the two unknowns in order to obtain two unknowns (temperature and distance). In other words, the processing unit uses two equations (first measurement signal and second measurement signal) relating to the two unknowns in order to obtain the two unknowns (temperature and distance). The processing unit can detect the temperature of the rotator when the position of the rotator changes in accordance with the temperature change of the rotator during the operation of the fluid machine.

  Note that the distance between the first measurement region and the second measurement region and the sensor may change during one rotation of the rotator depending on the shape of the rotator. Various distances can be selected as the distance to be measured in such a case. For example, the rotational position of the rotating body can be detected and the distance at the predetermined rotational position can be obtained. Alternatively, when the position where the first measurement signal and the second measurement signal reach the maximum value or the minimum value is a specific position during one rotation of the rotating body, only the maximum value or the minimum value is used. The distance between the first measurement region and the second measurement region at the position where the maximum value or the minimum value is reached and the sensor can be detected. The magnitudes of the first measurement signal and the second measurement signal depend on the materials of the first measurement area and the second measurement area, the distance between the first measurement area and the second measurement area and the sensor, and the like. To do.

  In the second embodiment, the linear expansion coefficient of the first measurement region and the linear expansion coefficient of the second measurement region are substantially the same. Since the linear expansion is substantially the same, the surfaces of the first measurement region and the second measurement region, which are different materials, are on the same distance, that is, on the same plane when viewed from the sensor. Therefore, even if there is a slight difference in the linear expansion coefficient, if the thickness of the target member that is the measurement target in the first measurement region and the target member that is the measurement target in the second measurement region is thin, the expansion will occur. Since the length to be shortened, there is substantially no problem.

  To what extent a step due to linear expansion between the surfaces of the first measurement region and the second measurement region can be allowed, that is, the linear expansion coefficient of the first measurement region and the linear expansion coefficient of the second measurement region are substantially equal to each other. The criteria for judging that they are the same size are as follows. For example, in certain types of dry vacuum pumps, the step is preferably less than 0.01 mm, which is the measurement accuracy of the distance between the first measurement region and the second measurement region and the sensor (ie, clearance). In a fluid machine in general, it is desirable that the step due to linear expansion is less than the measurement accuracy of the managed gap.

  In the third embodiment, the difference in intensity between the first magnetic field and the second magnetic field after the first measurement region and the second measurement region change in temperature is the first measurement region and the second magnetic field. The second measurement region is configured to be larger than the difference in strength between the first magnetic field and the second magnetic field before the temperature change.

In the fourth embodiment, the first measurement region and the region adjacent to the second measurement region can be opposed to the sensor, and the first measurement region and the second measurement that are opposed to the sensor. A configuration is employed in which there is no step between the surface of the region and the surface of the adjacent region facing the sensor.

  In a fifth aspect, the processing unit includes an impedance signal corresponding to each of the first measurement signal and the second measurement signal from each of the first measurement signal and the second measurement signal, and A signal of any one of the resistance signals is generated, and from the generated signal, the temperature of the at least one region, and at least one region of the first measurement region and the second measurement region The distance between the sensor and the sensor is detected.

  In a sixth aspect, the sensor outputs a third measurement signal when the sensor does not face the first measurement region and the second measurement region, and the processing unit outputs the first measurement signal and The second measurement signal is corrected by the third measurement signal.

  In the seventh embodiment, a rotating body having a region capable of generating a magnetic field, a main body having a sensor disposed at a position facing the region, and a magnetic field that can be generated by the region are detected by the sensor and output. A processing unit for processing the measured signal, wherein the measurement signal can vary depending on the temperature of the region, and the processing unit depends on the temperature of the region based on the measurement signal. The fluid machine is configured to generate at least one of an impedance signal and a resistance signal that change in response, and detect the temperature of the region from the at least one signal.

  In an eighth mode, the first measurement region having the first material and capable of generating the first magnetic field, and the second magnetic material having the second material different from the first material have the first magnetic field. A second measurement region capable of generating a second magnetic field different from the first measurement region, wherein the first material and the second material are magnetic bodies, the rotating body, the first measurement region, and A main body having a sensor that is disposed at a position facing the second measurement region and capable of detecting the first magnetic field and the second magnetic field; and the sensor configured to detect the first magnetic field and the second magnetic field. And a processing unit that processes the first measurement signal and the second measurement signal that are detected and output by the first and second magnetic fields, the first magnetic field and the second magnetic field being the first measurement region and the second measurement signal, respectively. The first measurement signal and the second measurement signal can be changed depending on the temperature of the measurement region of the first measurement signal and the second measurement signal. The first measurement signal and the second measurement signal can be changed depending on the temperature of the first measurement region and the second measurement region, and the first measurement signal and the second measurement signal can be changed. The processing unit can change depending on a distance between the measurement region and the sensor, and the processing unit can determine the first measurement region and the second measurement signal based on both the first measurement signal and the second measurement signal. The configuration is a fluid machine that detects the temperature of two measurement regions and the distance between the first measurement region and the second measurement region and the sensor.

FIG. 1 is an overall view of a vacuum pump 20 according to an embodiment of the present invention. FIG. 2 shows only one of the two rotors 24. FIG. 3 shows the relationship between temperature and sensor output for a plurality of different gaps g1, g2, g3, g4... Gx. FIG. 4 shows the relationship between temperature and sensor output for a plurality of different gaps g1, g2, g3, g4... Gx. FIG. 5 shows the absolute value Va1 of impedance as a horizontal line 46 on the same graph as FIG. FIG. 6 is a graph in which the absolute value Vb1 of impedance is displayed as a horizontal line 50 on the same graph as FIG. FIG. 7 is a diagram showing temperatures 481, 482, 483, 484 and gaps g1, g2, g3, g4 corresponding to these temperatures. FIG. 8 is a diagram showing temperatures 521, 522, 523, and 524 and gaps g1, g2, g3, and g4 corresponding to these temperatures. FIG. 9 is a diagram in which the curve 54 and the curve 56 are displayed in one figure with the horizontal axis representing temperature and the vertical axis representing a gap. FIG. 10 is a diagram for explaining an equivalent circuit of the sensor 36. FIG. 11 shows the relationship between the resistance component of the impedance Zin and the temperature. FIG. 12 shows the relationship between the inductance component of the impedance Zin and the temperature. FIG. 13 is a diagram showing a temperature curve 76 of the material of the rotor 30 directly measured by the thermocouple and a temperature curve estimated from the approximate expression of the signal of the sensor 36 measured in a non-contact manner. FIG. 14 is a diagram for explaining a method for avoiding a measurement error due to the position variation of the rotor 24. FIG. 15 is a diagram for explaining a method for avoiding a measurement error due to the position variation of the rotor 24. FIG. 16 shows the structure of the sensor 36.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same or corresponding members are denoted by the same reference numerals, and redundant description is omitted. The fluid machine of one embodiment of the present invention is a dry pump. The dry pump is a vacuum pump that does not use oil or liquid in the vacuum chamber. In fields such as the semiconductor manufacturing industry, dry pumps are used to improve product yield and maintainability. The fluid machine of one embodiment of the present invention is a roots type vacuum pump that is a typical pump in a dry pump. Note that the present invention can be applied to other types of rotors as long as the end surface of the rotor has a flat surface and another material different from the material of the rotor can be added to the end surface.

  A roots type vacuum pump 20 is shown in FIGS. FIG. 1 is an overall view of the vacuum pump 20 in which a part of the casing 22 of the vacuum pump 20 is removed so that the inside of the vacuum pump 20 can be seen. In the roots-type vacuum pump 20, two rotors 24 (rotating bodies) are contained in a box called a casing 22. FIG. 2 shows only one of the two rotors 24. FIG. 2B is a view of the rotor 24 of FIG. The two rotors 24 rotate at the same period in opposite directions. The rotors 24 and the rotor 24 and the casing 22 are not in contact with each other, and rotate while maintaining a slight gap to transfer gas while compressing it. The rotor 24 has a multistage structure. In the case of FIG. 2, the rotor 24 has a six-stage structure in the direction of the rotary shaft 26 of the vacuum pump 20. Each step has a trefoil shape. A low-pressure fluid lower than the atmospheric pressure is sucked from a suction port (not shown) at the position of the rotor 28 which is the first stage. It can be compressed to atmospheric pressure in six stages, and can be exhausted into the atmosphere from a discharge port (not shown) at the position of the rotor 30 in the sixth stage. The root-type vacuum pump 20 in this figure has a three-leaf shape, but the root-type vacuum pump includes a two-leaf pump and a three-leaf or more pump. The present invention is not limited to the number of leaves, and the present invention can also be applied to a two-leaf pump or a three-leaf or more pump.

  In the present embodiment, the rotor 30 includes a first measurement region 32 that can generate a first magnetic field, and a second measurement region 34 that can generate a second magnetic field different from the first magnetic field. The second measurement region 34 is made of the same material as the rotor 30 (that is, the entire rotor 24). The first measurement region 32 is a region made of a material different from the material of the rotor 30 provided for temperature measurement. The first measurement region 32 is provided on one of the three leaves of the rotor 30 and has a disk shape. The first measurement region 32 is provided in a leaf different from the leaf in which the second measurement region 34 is provided among the three leaves of the rotor 30.

  The second measurement region 34 is a part of the rotor 30 and does not have a special shape that can be distinguished from other parts of the rotor 30. The circle shown as the second measurement region 34 indicates the outer diameter of the detection region of the sensor 36 when the center of the circle coincides with the center of the detection region of the sensor 36 while the rotor 30 is rotating. That is, the circle indicates the size of the detection area of the sensor 36. For identification of the first measurement region 32 and the second measurement region 34, for example, a rotational position detection unit that detects the rotational position of the rotor 30 can be used. Alternatively, the output of the sensor 36 shows different peak values in the first measurement region 32 and the second measurement region 34. By detecting different peak values, the first measurement region 32 and the second measurement region 34 can be identified.

  The casing 22 which is a part of the main body has a sensor 36. The sensor 36 is disposed at a position that can face the first measurement region 32 and the second measurement region 34. The sensor 36 can detect the first magnetic field and the second magnetic field. The vacuum pump 20 includes a processing unit 38. The processing unit 38 processes the first measurement signal and the second measurement signal output by the sensor 36 detecting and outputting the first magnetic field and the second magnetic field. The main body includes a casing 22, an intake side cover 128, and an exhaust side cover 130. The intake side cover 128 and the exhaust side cover 130 are separate parts from the casing 22 and are screwed to the casing 22.

  Since the first magnetic field and the second magnetic field can change depending on the temperatures of the first measurement region 32 and the second measurement region 34, the first measurement signal and the second measurement signal are It can change depending on the temperature of the first measurement region 32 and the second measurement region 34. The reason why the first magnetic field and the second magnetic field can be changed depending on the temperature of the first measurement region 32 and the second measurement region 34 is that the first measurement region 32 and the second measurement region 34 are changed. This is because it is a metal and the resistance and permeability of the metal change depending on the temperature. The first magnetic field and the second magnetic field change in accordance with the change in resistance or magnetic permeability of the first measurement region and the second measurement region. The sensor 36 detects changes in the first magnetic field and the second magnetic field.

  The first measurement signal and the second measurement signal can change depending on the distance between the first measurement region 32 and the second measurement region 34 and the sensor 36. Based on both the first measurement signal and the second measurement signal, the processing unit 38 detects the temperatures of the first measurement region 32 and the second measurement region 34, and the first measurement region 32 and the second measurement signal. The distance between the measurement region 34 and the sensor 36 is detected. In the present embodiment, the temperature of the first measurement region 32 is considered to be substantially equal to the temperature of the second measurement region 34.

  In the present embodiment, the first measurement region 32 has a first material, and the second measurement region 34 has a second material different from the first material. The first measurement area 32 has a disk shape. The first measurement region 32 is formed in the rotor 30 by embedding, shrink fitting, bonding or welding the disk. The surface shape of the first measurement region 32 viewed from the sensor 36 is not limited to a circle, and may be other shapes, for example, a polygon such as a quadrangle, an ellipse, or the like. The first measurement region 32 may be formed by coating or spraying. The overall shape may be a cylinder, a cone, a prism, a truncated cone, a truncated pyramid, or the like.

  The first material is, for example, stainless steel (SUS), titanium, nickel, or the like. The second material is a material of the rotor 24, and is, for example, Ni-resist cast iron, ductile cast iron (FCD) or the like. In FIG. 2, the distance between the first measurement region 32 and the sensor 36 when the first measurement region 32 faces the sensor 36 is the second measurement when the second measurement region 34 faces the sensor 36. The distance between the region 34 and the sensor 36 is the same. That is, there is no step between the surface of the first measurement region 32 and the surface of the rotor 30 adjacent to the first measurement region 32.

The sensor 36 is an eddy current sensor, and the first magnetic field and the second magnetic field are generated by eddy currents generated by the eddy current sensor in the first measurement region 32 and the second measurement region 34. The principle of temperature measurement by the sensor 36 when the sensor 36 is an eddy current sensor is as follows.
(1) An alternating current is applied to the exciting coil of the sensor 36 by an alternating current source.
(2) An alternating magnetic field is generated around the sensor 36 by the alternating current.
(3) When the first measurement region 32 and the second measurement region 34 come to positions facing the sensor 36, eddy currents are generated in the first measurement region 32 and the second measurement region 34.
(4) Due to the eddy current, a magnetic field is generated in the first measurement region 32, the second measurement region 34, and the periphery thereof.
(5) The generated magnetic field is detected by the detection coil of the sensor 36.
(6) The first measurement region 32 and the second measurement region 34 and the magnetic fields generated around the first measurement region 32 and the second measurement region 34 vary depending on the temperatures of the first measurement region 32 and the second measurement region 34. The sensor 36 detects a change in the magnetic field.
(7) The processing unit 38 obtains a change in temperature from the change in the magnetic field, as will be described later.

  In addition, it is preferable that the linear expansion coefficient of the 1st measurement area | region 32 and the linear expansion coefficient of the 2nd measurement area | region 34 are substantially the same magnitude | size. In addition, the first measurement region 32 and the second measurement region 34 have different intensities between the first magnetic field and the second magnetic field after the first measurement region 32 and the second measurement region 34 change in temperature. It is preferable that the difference between the strengths of the first magnetic field and the second magnetic field before the temperature change is larger.

  In the present embodiment, the processing unit 38 generates an impedance signal corresponding to each of the first measurement signal and the second measurement signal from each of the first measurement signal and the second measurement signal. From the generated signal, the temperature of the first measurement region 32 and the second measurement region 34 and the distance between the first measurement region and the second measurement region and the sensor 36 are detected. The processing unit 38 may generate a resistance signal corresponding to each of the first measurement signal and the second measurement signal from each of the first measurement signal and the second measurement signal.

  In this embodiment, when the sensor 36 does not face the first measurement region 32 and the second measurement region 34, that is, when the sensor 36 faces the region 40 between the three leaves of the rotor 30, A third measurement signal is output. The processing unit 38 corrects the first measurement signal and the second measurement signal with the third measurement signal. The correction is, for example, a process of adding or subtracting the third measurement signal to the first measurement signal and the second measurement signal. The purpose of performing such correction is to eliminate the influence on the first measurement signal and the second measurement signal due to the temperature change of the sensor 36 itself. When the first measurement region 32 and the second measurement region 34 are not within the detection range of the sensor 36, a third measurement signal is obtained, and data for calibration of the first measurement signal and the second measurement signal is obtained. To get

  Next, details of one embodiment of a method in which the processing unit 38 detects the temperature of the two measurement regions 34 and the distance between the first measurement region and the second measurement region and the sensor 36 will be described.

  The temperature of the rotor 24 including the rotor 30 is important information for improving the reliability of the pump, and there is a demand for measuring the temperature of the rotor 24 during operation in real time. This is because if the temperature of the rotor 24 during operation is known, feedback to the development stage of the vacuum pump 20 is possible, and the operating conditions of the vacuum pump 20 can be optimized. Hereinafter, the rotor 30 will be described as an example, but detection is similarly performed in other portions of the rotor 24 other than the rotor 30. As shown in FIG. 2, the temperature of the end face of the rotor 30 is measured by a sensor 36 that is an eddy current sensor. The signal of the sensor 36 is changed not only by the temperature of the rotor 30 but also by a gap g which is a distance between the rotor 30 and the sensor 36. Hereinafter, the gap g may be referred to as a clearance g.

A material having a different resistance value from the material of the rotor 30 is embedded in the rotor 30 to form the first measurement region 32. When the temperature is the same and the distance is the same, both the temperature and the gap are estimated by measuring eddy currents of two types of materials (that is, the first measurement region 32 and the second measurement region 34). This is similar to, for example, solving a binary linear equation. There are two unknowns, that is, the temperature (Tr) of the rotor 30 and the gap (g). Two measured values, that is, the absolute value (Va) of the impedance obtained from the rotor 30 (second measurement region 34) and the impedance obtained from the buried metal (first measurement region 32). Absolute value (Vb). The following relational expression holds between these four quantities.
Va = Fa (Tr, g), that is, Va is a function Fa of Tr and g.
Vb = Fb (Tr, g), that is, Vb is a function Fb of T and g.
(Tr, g) is obtained from Va = Fa (Tr, g) and Vb = Fb (Tr, g).
The temperature of the rotor 30 is, for example, in the range from room temperature to 250 ° C., the temperature of the casing 22 is, for example, from room temperature to 200 ° C., and the accuracy of temperature measurement of the rotor 30 is ± several degrees to 10 ° C. It is preferable.

  The method for estimating the temperature of the rotor 30 is as follows. Regarding the material of the first measurement region 32, the relationship between the temperature and the output of the sensor is measured in advance for a plurality of different gaps g1, g2, g3, g4. Thus, the graph shown in FIG. 4 is created. Regarding the material of the second measurement region 34, the relationship between the temperature and the output of the sensor is measured in advance for a plurality of different gaps g1, g2, g3, g4. Then, the graph shown in FIG. 3 is created. 3 and 4, the size of the gap increases in the order of g1, g2, g3, g4... Gx. That is, g1 <g2 <g3 <g4 <... <gx.

  3 and 4, the horizontal axis represents temperature, and the vertical axis represents the absolute value of impedance. The curves 421, 422, 423, 424, and 42x in FIG. 3 show the relationship between the temperature and the absolute value of the impedance when the gap g is g1, g2, g3, g4. Show. Curves 441, 442, 443, 444, and 44x in FIG. 4 show the relationship between the temperature and the absolute value of the impedance when the gap g is g1, g2, g3, g4... Gx, respectively. Show. How to obtain the curves 421, 422, 423, 424, 42x and the curves 441, 442, 443, 444, 44x will be described later.

  In addition, the absolute value (V0) of impedance at several temperatures of the sensor when the sensor is not facing the material is also measured in advance. This data is obtained by calculating the absolute value of the impedance when the sensor 36 is opposed to the region 40 at the time of measurement in the actual pump 20, and the temperature of the sensor 36 when the data shown in FIGS. This is because the influence of the temperature difference of the sensor 36 at the time of measurement in the actual pump 20 is corrected.

  Next, it is assumed that the absolute value Va1 of the impedance is obtained from the output of the sensor 36 with respect to the second measurement region 34 during the operation of the pump 20 as shown in FIG. FIG. 5 shows the absolute value Va1 of impedance as a horizontal line 46 on the same graph as FIG. Temperatures 481, 482, 483, 484 corresponding to the intersections of the horizontal line 46 and the curves 421, 422, 423, 424 are candidate values as temperatures of the second measurement region 34.

  Similarly, assume that the absolute value Vb1 of the impedance is obtained from the output of the sensor 36 with respect to the first measurement region 32 during the operation of the pump 20, as shown in FIG. FIG. 6 is a graph in which the absolute value Vb1 of impedance is displayed as a horizontal line 50 on the same graph as FIG. The temperatures 521, 522, 523, and 524 corresponding to the intersections of the horizontal line 50 and the curves 441, 442, 443, and 444 are candidate values as the temperature of the first measurement region 32.

  FIG. 7 is a plot of temperatures 481, 482, 483, and 484 in FIG. 5 and gaps g1, g2, g3, and g4 corresponding to these temperatures, with the horizontal axis representing the temperature and the vertical axis representing the gap. Similarly, FIG. 8 is a plot of temperatures 521, 522, 523, and 524 in FIG. 6 and gaps g 1, g 2, g 3, and g 4 corresponding to these temperatures, with the horizontal axis representing the temperature and the vertical axis representing the gap. . As shown in FIGS. 7 and 8, these data are on a curve 54 and a curve 56, respectively. FIG. 9 shows the curves 54 and 56 displayed in one figure with the horizontal axis representing temperature and the vertical axis representing a gap. The temperature 58 and the gap 60 at the intersection of the curve 54 and the curve 56 are the temperature 58 and the gap 60 of the rotor 30.

  Next, an example of how to obtain the curves 421, 422, 423, 424 and the curves 441, 442, 443, 444 shown in FIGS. A diagram for explaining an equivalent circuit of the sensor 36 is shown in FIG. In FIG. 10, a sensor coil 62 is wound around the tip of the sensor 36. A resistor 64 is connected in series to the sensor coil 62. An AC power source 66 is connected to this circuit. A high frequency voltage having a constant frequency and a constant voltage is applied to the sensor coil 1 by an AC power source 66 to create a high frequency magnetic field. The rotor 30 facing the sensor 36 is considered to be a multi-layer coil of metal wire. The rotor 30 is considered to have a resistance 68 and an inductance 70.

When the temperature of the rotor 30 changes, the resistance 68 (R ₀ ) and the inductance 70 (Lo) change. The resistor 68 (R ₀ ) is proportional to the resistivity (ρ). The resistivity (ρ) changes as ρ = ρ ₀ (1 + αt) when the temperature (t) changes. Here, α is a resistance temperature coefficient. ρ ₀ is the resistivity at 0 ° C. The resistance 68 changes as the resistivity changes from R ₀ = ρ · L / S.

The following relational expression is established for the inductance 70 (Lo).
Lo∝ metal rod radius ² * number of coil turns ² * Nagaoka coefficient / thickness of metal rod
Here, the Nagaoka coefficient is a coefficient for obtaining the inductance of the finite length solenoid. When the size (outer shape) of the rotor 30 changes due to the temperature change of the rotor 30, the inductance (Lo) changes. The impedance Zin when the sensor 36 is viewed from the AC power supply 66 is as follows. It is assumed that the coupling coefficient between the sensor coil 62 and the inductance 70 is M.

Ｚｉｎ＝抵抗成分＋インダクタンス成分であり、それぞれの成分を、以下のように書く。Ｚｉｎ＝（Ｒｓ＋Ｒ（ｄ））＋ｊｗ（Ｌｓ−Ｌ（ｄ））
このとき、ロータ３０に依存する量であるＬ（ｄ）、Ｒ（ｄ）は、以下のようになる。

Zin = resistance component + inductance component, and each component is written as follows. Zin = (Rs + R (d)) + jw (Ls−L (d))
At this time, L (d) and R (d), which are amounts depending on the rotor 30, are as follows.

抵抗成分、インダクタンス成分は、温度依存性を有するため、一次側であるセンサコイル６２のインピ−ダンスZinを計測することにより、非接触で二次側の金属（ロータ３０）の温度を観測できる。

Since the resistance component and the inductance component have temperature dependency, the temperature of the secondary side metal (rotor 30) can be observed in a non-contact manner by measuring the impedance Zin of the sensor coil 62 which is the primary side.

  The data shown in FIGS. 3 and 4 is acquired as follows, for example. About the material of the 1st measurement area | region 32 and the material of the 2nd measurement area | region 34, those temperature is measured with a thermometer. The impedance Zin is obtained from the output of the sensor 36. FIG. 11 shows the measurement result of the resistance component of the impedance Zin, and FIG. 12 shows the measurement result of the inductance component of the impedance Zin. The horizontal axis indicates the temperature, and the vertical axis indicates the resistance component and the inductance component, respectively. It is. Curves 72 and 73 in FIGS. 11 and 12 are actual measurement values regarding the sample, and curves 74 and 75 are obtained by approximating the curves 72 and 73 by the least square method, respectively. As the function approximation, for example, a cubic curve is used. In this way, the curves 421, 422, 423, 424 and the curves 441, 442, 443, 444 are obtained.

  FIG. 13 is a diagram showing a temperature curve 76 of the rotor 30 directly measured by a thermocouple and a temperature curve of the rotor 30 estimated from an approximate expression of the signal of the sensor 36. The horizontal axis is time, and the vertical axis is temperature. Measurement was performed while changing the temperature of the sample with time. The temperature curve 78 is a temperature obtained from the resistance component of the impedance Zin in FIG. 11, and the temperature curve 80 is a temperature obtained from the inductance component of the impedance Zin in FIG. The temperature curve 76 is in good agreement with the temperature curve 78 and the temperature curve 80. From these, it can be seen that the relationship between the impedance Zin and the temperature of the material of the rotor 30 can be obtained with high accuracy by the least square method.

  Next, a method for reducing the influence on temperature measurement due to the position of the rotor 30 changing in the axial direction of the rotating shaft 26 during operation will be described. The reason why the temperature measurement is affected when the position of the rotor 30 fluctuates in the direction of the rotating shaft 26 during operation will be described.

  The sensors are mounted at various locations on the casing 22 of the pump 20 depending on which part of the rotor 24 is to be measured. When the sensor measures the temperature of the outer periphery 122 of the rotor 24, it is attached to a position 82 on the outer periphery 124 that faces the axial direction of the rotary shaft 26 from the outer periphery 124 of the casing 22, as shown in FIG. 1. When measuring the temperature of the rotating shaft 26, it is installed in an interstage 126 that is a part of the casing 22, and is attached to a position 86 that faces the axial direction from the interstage 126. When installed at the positions 82 and 86, even if the position of the rotor 30 fluctuates in the axial direction of the rotating shaft 26, the distance between the rotor 30 and the sensor does not change, so the temperature measurement is not affected.

  However, when the sensor measures the temperature of the surface of the rotor 24 perpendicular to the rotation axis 26, the sensor is installed at the following position. That is, the position 84 facing the exhaust side in the intake side cover 128, the position 88 facing the exhaust side from the interstage between the stages that are a part of the casing 22, and the interstage that is a part of the casing 22. The sensor 36 is attached at a position 90 facing the intake side from the interstage and a position 92 facing the intake side in the exhaust side cover 130. When installed at these positions, if the position of the rotor 24 fluctuates in the direction of the rotating shaft 26, the distance between the rotor 24 and the sensor changes, which affects temperature measurement. In order to solve this problem, as shown in FIG. 14, the position 90 is located at the position 90 facing the intake side from the interstage and the position 88 facing the exhaust side from the interstage within the interstage. One sensor is used. This will be described below.

A temperature of a specific rotor 94 of the rotor 24 is measured by two or more sensors from both sides of the rotor 94, and a measurement error due to a position variation of the rotor 24 is obtained by a difference value of sensor signals output from the two or more sensors. To avoid. A specific method will be described with reference to FIGS. Assume that the rotor 94 is between the rotor 96 and the rotor 98. Assume that the sensor 100 is disposed between the rotor 94 and the rotor 96. Assume that the sensor 102 is disposed between the rotor 94 and the rotor 98. Assume that the rotor 94 moves to the left and reaches the position of the rotor 104. Since the sensor 100 approaches the rotor 94, the magnitude of the signal output from the sensor 100 increases. The magnitude of the increased signal is Vs1. Since the sensor 102 is separated from the rotor 94, the magnitude of the signal output from the sensor 102 decreases. Let Vs2 be the magnitude of the reduced signal.

  The distance 106 between the rotor 94 and the sensor 100 varies by the distance 108 between the rotor 94 and the rotor 104 and decreases to the distance 110 between the rotor 104 and the sensor 100. At this time, the distance 112 between the rotor 94 and the sensor 102 varies by the distance 108 between the rotor 94 and the rotor 104 and increases to the distance 110 between the rotor 104 and the sensor 102.

  In order to cancel the variation in the position of the rotor 94, the signals of the two sensors are added and divided by two. That is, assuming that the signal magnitude Vs3 after cancellation is Vs3 = (Vs1 + Vs2) / 2. FIG. 15 shows a temperature curve 118 by the sensor 100, a temperature curve 116 by the sensor 102, and a corrected temperature curve 120 when the horizontal axis is the output signal of the sensor and the vertical axis is temperature.

  In addition, you may install the magnetic sheets 134 and 136 for a magnetic shield in the back surface of the sensors 100 and 102. FIG. By installing, it is possible to prevent the magnetism generated by the metal (the rotors 96, 98, etc.) on the back surfaces of the sensors 100, 102 from entering the sensors 100, 102. As a result, the influence of the metal (the rotors 96, 98, etc.) on the temperature measurement of the rotor 94 can be avoided by the magnetic sheets 134, 136.

Next, a description will be given of obtaining the gap (g) and the temperature (T) by a method different from the method shown in FIGS. The first measurement region 32 has a first material, and the second measurement region 34 has a second material different from the first material. The resistivity is generally different for different materials. The sensor 36 detects magnetism from two types of metal bodies (first material and second material) having different temperature coefficients (α) of resistivity. The gap (g) and temperature (T) can be derived by solving the following equations concerning the two sensor signals V1 and V2 from the two detected sensor signals V1 and V2 (for example, absolute values of impedance).
[Equation 3]
V1 = f _α1 (g, T)
V2 = f _α2 (g, T)

Here, f _α1 and f _α2 are equations indicating the relationship between the sensor signals V1 and V2 relating to the first material and the second material, the gap (g), and the temperature (T), respectively. When the gap (g) and the temperature (T) are within a certain range, f _α1 and f _α2 can be approximated by a linear expression relating to two unknowns (gap (g) and temperature (T)). In this case, since Equation 3 is two equations relating to two unknowns (gap (g) and temperature (T)), it is a binary linear equation.

Equation 3 can be displayed as Equation 4 below.
[Equation 4]
a1 * g + b1 * T = c1
a2 * g + b2 * T = c2
Here, a1, b1, and c1 are a gap (g), a coefficient of temperature (T), and a variable appearing in an equation obtained by approximating f _α1 with a linear expression. a2, b2, c2 is to approximate the f.alpha ₂ in a linear equation, a gap (g) appearing in the resulting equation, the coefficient of temperature (T), and a variable. Equation 4 can be solved by matrix calculation as shown in Equation 5 below, and the gap (g) and temperature (T) can be derived.

In the same way as the method used in Equations 3 to 5, the gap (g) is different and the temperature coefficient (α) and temperature (T) are the same for the same metal (same material), for example, the first measurement region 32. Applicable when With respect to the first measurement region 32, the sensor 36 detects magnetism. From the two detected sensor signals V1 and V2 (for example, absolute values of impedance), the following equations relating to the two sensor signals V1 and V2 can be solved to derive the temperature coefficient (α) and the temperature (T). [Equation 6]
V1 = f _g1 (α, T)
V2 = f _g2 (α, T)
Here, f _g1 and f _g2 respectively represent the relationship between the sensor signals V1 and V2 related to the first material when the gap (g) is g1 and g2, and the temperature coefficient (α) and the temperature (T). It is a formula which shows. When the temperature coefficient (α) and the temperature (T) are within a certain range, f _g1 and f _g2 can be approximated by a linear expression relating to two unknowns (temperature coefficient (α) and temperature (T)). In this case, since Equation 4 is two equations relating to two unknowns (temperature coefficient (α) and temperature (T)), it is a binary linear equation. Similar to Equation 3, Equation 6 can be solved by matrix calculation, and the temperature coefficient (α) and temperature (T) can be derived.

  Next, the configuration of the sensor 36 will be described. The sensor 36 installed in the casing 22 can have a structure shown in FIG. On the ceramic layer 140, nickel copper is formed, and a spiral coil 138 is manufactured by etching. Coil 138 is covered with polyimide layer 142. By covering with the polyimide layer 142, the coil 138 has heat resistance. The coil 138 is a single coil, and can serve both as an excitation coil and a detection coil. In the case of serving both as an excitation coil and a detection coil, there are two lead wires 144 from the coil. Further, the excitation coil and the detection coil may be provided separately, and the coil 138 may be composed of two coils. Two coils arrange | position an exciting coil on a detection coil in the axial direction of a coil.

According to the embodiment of the present invention, the temperature of the rotor can be measured in a non-contact manner while the rotor such as a dry pump is rotating. The measurement range is from room temperature to 400 ° C. or higher. The advantages of using an eddy current sensor or a magnetic sensor are as follows.
(1) The gap (clearance) during pump operation can be confirmed. The confirmed data can be reflected in the pump design. If the rotor temperature and clearance are known, it will be easier to take measures against failure by increasing the material used to analyze the cause of the pump stopping due to a malfunction. By measuring the clearance during operation, a new product with improved reliability will be completed earlier than before. Since the clearance can be made appropriate, the efficiency of the pump is increased, leading to energy saving.
(2) In a semiconductor manufacturing process in which a pump is used, for example, the internal temperature of the pump can be managed according to the gas used in the semiconductor manufacturing process. As a result, it is possible to reduce the influence of the temperature on the gas used in the process or the influence of the gas etc. on the pump. As an example of a method for managing the internal temperature of the pump, a flow path for circulating cooling water is provided inside the rotating body, and the rotating body is cooled or heated according to the measured temperature of the rotating body. (3) It is possible to stop the pump at an early stage before detecting abnormalities in the clearance and temperature of the rotor and leading to the destruction of the pump.

  It can be measured in a non-contact manner that the rotor rotating at high speed (for example, 8000 rpm) is at a high temperature (50 to 400 ° C.). In order to stably measure the temperature and distance of the rotor rotating at high speed, for example, when one of the three blades (leaves) of the rotor passes, the sensor can measure a plurality of times. is necessary. For this reason, the sampling speed of the measurement value output from the sensor needs to be about 1 kHz or more. For example, in the case of 3000 rotations / minute, if there are 6 measurement points for each of the 3 leaves, 3000 rotations / minute / 60 s * 3 leaves * 6 points = 900 Hz.

  The rotational speed of the rotor can be measured based on the output signal from the sensor. When the rotor has three blades, for example, the output signal from the sensor differs greatly when facing the blades and when not facing the blades (when facing the region between the blades). By setting a threshold value for the magnitude of the output signal, the number of blade passages can be measured. Thus, by determining the level of the output signal, the rotational speed of the rotor can be measured without contact.

  In the temperature measurement or the like, when the output signal from the sensor is weak, such as when the sensor is near the end of the rotor, it is preferable to measure the temperature and distance without the sampling data at that time.

  Further, in the temperature measurement or the like, the influence of the temperature of the sensor itself on the temperature measurement of the rotor can be corrected by using the output of the sensor when the rotor blades are not opposed to the sensor. This is performed as follows, for example. The sensor output when the rotor blades are not facing the sensor can be added to or subtracted from the sensor output when the rotor blades are facing the sensor, thereby correcting the influence of the temperature change of the sensor itself. .

In the embodiment shown in FIG. 1, the first material is, for example, stainless steel (SUS), titanium, nickel, and the like, and the second material is the material of the rotor 24. The sensor 36 is an eddy current sensor. The present invention is not limited to such an embodiment, and the first material and the second material may be magnetic materials. At this time, the first measurement area 32 and the second measurement area 34 may be, for example, disk-shaped. The first measurement region 32 and the second measurement region 34 can be formed in the rotor 30 by embedding, shrink-fitting, bonding or welding a magnetic disk. The surface shape of the first measurement region 32 viewed from the sensor 36 is not limited to a circle, and may be other shapes, for example, a polygon such as a quadrangle, an ellipse, or the like. The first measurement region 32 may be formed by coating or spraying. The overall shape may be a cylinder, a cone, a prism, a truncated cone, a truncated pyramid, or the like.
When the first material and the second material are magnetic bodies, the sensor 36 is a coil for detecting a magnetic field generated by the magnetic body.

  As mentioned above, although the example of embodiment of this invention was demonstrated, above-described embodiment of this invention is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention naturally includes equivalents thereof. In addition, any combination or omission of each constituent element described in the claims and the specification is possible within a range where at least a part of the above-described problems can be solved or a range where at least a part of the effect is achieved. It is.

DESCRIPTION OF SYMBOLS 20 ... Pump 22 ... Casing 24 ... Rotor 32 ... 1st measurement area 34 ... 2nd measurement area 36 ... Sensor 38 ... Processing part

Claims (8)

A first measurement region having a first material and capable of generating a first magnetic field; and a second measurement material having a second material different from the first material and different from the first magnetic field. A rotating body having a second measurement region capable of generating a magnetic field;
A main body having an eddy current sensor that is disposed at a position that can face the first measurement region and the second measurement region, is capable of generating the first magnetic field and the second magnetic field, and is detectable; ,
A processing unit that processes the first measurement signal and the second measurement signal output by the sensor detecting and outputting the first magnetic field and the second magnetic field;
The first magnetic field and the second magnetic field can change depending on the temperature of the first measurement region and the second measurement region, so that the first measurement signal and the second measurement can be performed. The signal can vary depending on the temperature of the first measurement region and the second measurement region,
The first measurement signal and the second measurement signal can be changed depending on the distance between the first measurement region and the second measurement region and the sensor,
The processing unit, based on both the first measurement signal and the second measurement signal, the temperature of the first measurement region and the second measurement region, and the first measurement region and the A fluid machine, wherein a distance between a second measurement region and the sensor is detected.   The fluid machine according to claim 1, wherein the linear expansion coefficient of the first measurement region and the linear expansion coefficient of the second measurement region are substantially the same.   The difference between the strengths of the first magnetic field and the second magnetic field after the temperature of the first measurement region and the second measurement region is changed is determined by the first measurement region and the second measurement region. 3. The fluid machine according to claim 1, wherein the fluid machine has a larger difference in strength between the first magnetic field and the second magnetic field before the temperature change. 4.   The region adjacent to the first measurement region and the second measurement region can be opposed to the sensor, the first measurement region and the surface of the second measurement region facing the sensor, and The fluid machine according to any one of claims 1 to 3, wherein there is no step between the surface of the adjacent region facing the sensor.   The processing unit is configured to select any one of an impedance signal and a resistance signal corresponding to each of the first measurement signal and the second measurement signal from each of the first measurement signal and the second measurement signal. And detecting the temperature of the at least one region and the distance between the first measurement region and the second measurement region and the sensor from the generated signal. The fluid machine according to any one of claims 1 to 4.   The sensor outputs a third measurement signal when the sensor does not face the first measurement region and the second measurement region, and the processing unit outputs the first measurement signal and the second measurement signal. The fluid machine according to claim 1, wherein the fluid machine is corrected by the third measurement signal. A rotating body having a region capable of generating a magnetic field;
A main body having a sensor arranged at a position capable of facing the region;
A processing unit that processes a measurement signal output by the sensor detecting and outputting a magnetic field that can be generated by the region;
The measurement signal can vary depending on the temperature of the region;
The processing unit generates at least one of an impedance signal and a resistance signal that vary depending on the temperature of the region based on the measurement signal, and determines the temperature of the region from the at least one signal. A fluid machine characterized by detecting. A first measurement region having a first material and capable of generating a first magnetic field; and a second measurement material having a second material different from the first material and different from the first magnetic field. A rotating body having a second measurement region capable of generating a magnetic field, wherein the first material and the second material are magnetic bodies;
A main body having a sensor that is disposed at a position facing the first measurement region and the second measurement region and capable of detecting the first magnetic field and the second magnetic field;
A processing unit that processes the first measurement signal and the second measurement signal output by the sensor detecting and outputting the first magnetic field and the second magnetic field;
The first magnetic field and the second magnetic field can change depending on the temperature of the first measurement region and the second measurement region, so that the first measurement signal and the second measurement can be performed. The signal can vary depending on the temperature of the first measurement region and the second measurement region,
The first measurement signal and the second measurement signal can be changed depending on the distance between the first measurement region and the second measurement region and the sensor,
The processing unit, based on both the first measurement signal and the second measurement signal, the temperature of the first measurement region and the second measurement region, and the first measurement region and the A fluid machine, wherein a distance between a second measurement region and the sensor is detected.

Images