Vacuum pump and control device for vacuum pump

Abstract

To provide a vacuum pump capable of accurately determining when to replace rotary vanes by creating an index which can quantitatively and easily determine a fatigue level of the rotary vanes according to an operation state of the pump, and a control device of the vacuum pump.SOLUTION: The vacuum pump that can determine when to replace rotary vanes includes rotary vanes built in a vacuum pump body, and a sensor disposed in the vacuum pump body to measure a physical amount related to the rotary vanes. The physical amount measured by the sensor during operation of the vacuum pump is extracted as a sample every prescribed time, and when the optional number of sampling extraction times passes, the highest physical amount range of the density of values of the physical amount at each sampling time up to the time point can be found. Therefore, physical amount upper limit values being upper limit values of the physical amount range and physical amount lower limit values being lower limit values of the physical amount range are defined, and each of intervals between the physical amount upper limit values and the physical amount lower limit values is made to change on a certain amount basis according to the magnitude of a physical amount.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a vacuum pump and a control device for a vacuum pump, and particularly to a vacuum pump and a control device for a vacuum pump that can accurately determine the timing of replacing a rotating blade by creating an index that can quantitatively and easily determine the fatigue condition of the rotating blade according to the operating conditions of the pump.

Background Art

[0002] With the recent development of electronics, the demand for semiconductors such as memories and integrated circuits has been rapidly increasing. These semiconductors are manufactured by doping impurities into a semiconductor substrate with extremely high purity to give electrical properties, or forming fine circuits on the semiconductor substrate by etching.

[0003] And these operations need to be performed in a chamber in a high vacuum state in order to avoid the influence of dust in the air. For evacuating this chamber, a vacuum pump is generally used, and in particular, a turbo molecular pump, which is one of the vacuum pumps, is frequently used because of its low residual gas and easy maintenance. In addition, in the semiconductor manufacturing process, there are many processes in which various process gases act on the semiconductor substrate, and the turbo molecular pump is used not only to evacuate the chamber but also to exhaust these process gases from the chamber.

[0004] By the way, the process gas may be introduced into the chamber in a high temperature state in order to enhance reactivity. And when these process gases are cooled to a certain temperature when being exhausted, they may become solid and deposit products in the exhaust system. And this kind of process gas may become low temperature and solid in the turbo molecular pump and adhere and deposit inside the turbo molecular pump.

[0005] When deposits of the process gas accumulate inside the turbo molecular pump, this deposit narrows the pump flow path and causes a decrease in the performance of the turbo molecular pump. To solve this problem, conventionally, a heater or a circular water-cooling pipe is wound around the outer periphery of the base portion of a turbo molecular pump, etc., and a temperature sensor is embedded in the base portion, etc., for example. Based on the signal of this temperature sensor, the temperature of the base portion is controlled to be maintained at a high temperature within a certain range by heating the heater and cooling by the water-cooling pipe (see Patent Document 1, Patent Document 2, and Patent Document 3).

[0006] Since it is difficult for products to deposit when the control temperature is higher, it is desirable to make this temperature as high as possible. On the other hand, when the base portion is heated to a high temperature in this way, the rotating blades may exceed the limit temperature when the exhaust load fluctuates or the ambient temperature changes to a high temperature, etc. To prevent such adverse effects, for example, a radioactive thermometer is installed in the base portion to constantly measure the temperature of the rotating blades. When the temperature exceeds a predetermined threshold value for a certain period of time and the pump is operating, a warning is issued. When the temperature further exceeds this value and the pump has been operating continuously for, for example, 30 seconds, the pump is stopped.

[0007] Under these operations, once the pump is started, it operates continuously for, for example, 1 to 5 years, etc. There are few opportunities to stop the pump except during overhaul maintenance of the pump. Therefore, usually, during the opportunity of overhaul maintenance of the turbo molecular pump, the necessity of replacing the rotating blades is judged. At that time, in addition to damage and discoloration that can be judged visually, the cumulative operation time of the pump recorded in the control circuit is used as a judgment item.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, even for rotor blades with the same cumulative operating time, in reality, due to the gas load during operation, the stress acting on the rotor blades is different, so the fatigue degree of the rotor blades may vary greatly. In addition, the temperature during operation cannot be ignored, and the higher the temperature during operation, the greater the fatigue degree of the rotor blades.

[0010] Just the information of the cumulative operating time of the pump recorded in the control circuit does not include information such as these gas loads and temperatures. Therefore, the necessity of replacing the rotor blades can only be judged with a certain degree of accuracy. As a result, as a manufacturer, it is recommended to judge on the safe side and recommend early replacement, but it is not easy to convince customers.

[0011] In addition, it may be insufficient to appropriately judge the fatigue condition of the rotor blades only based on the above-mentioned judgment items. For example, assuming that there is a situation where the temperature exceeds or drops below the threshold value repeatedly within 30 seconds, if the sampling period by the temperature sensor is a long period compared to the above-mentioned temperature fluctuations, it is estimated that a considerable degree of fatigue has accumulated in the rotor blades even though it cannot be detected as a pump abnormality.

[0012] Furthermore, if sampling from the temperature sensor is performed once every 0.5 seconds, for example, continuously accumulating this temperature data during operation for 1 to 5 years will result in an enormous amount of data. Analyzing this amount of data is also very burdensome in terms of the load required for analysis. Therefore, it is desirable to analyze the fatigue condition of the rotor blades in a state where the CPU mounted on the control circuit is not overly loaded. Furthermore, the usage conditions of the pump vary among customers, the temperature of the rotating blades during normal operation or the amount of current flowing through the motor driving the rotating blades vary from device to device, and there may be cases where the usage conditions of the pump are difficult to grasp. In these cases, it is desirable to analyze the fatigue level of the rotating blades according to the usage conditions. In particular, in the case of pumps that have been operating for a long time without any problems, although the fatigue level of the rotating blades varies depending on the pump or the way the device on which the pump is mounted is used, there is a possibility that differences may not appear in the analysis results of the fatigue level of the rotating blades.

[0013] The present invention has been made in view of such conventional problems, and an object thereof is to provide a vacuum pump and a control device for a vacuum pump that can accurately determine the timing of rotating blade replacement by creating an index that can quantitatively and easily determine the fatigue level of the rotating blades according to the operating conditions of the pump.

Means for Solving the Problems

[0014] Therefore, the present invention (Claim 1) is a vacuum pump having a rotating blade built in a vacuum pump body and a sensor disposed in the vacuum pump body for measuring a physical quantity related to the rotating blade. The vacuum pump includes a physical quantity extraction means for sampling and extracting the physical quantity measured by the sensor at predetermined time intervals during operation of the vacuum pump, and a physical quantity range detection means for finding the physical quantity range with the highest density of the measured values of the physical quantity at each sampling up to that point when the extraction by the physical quantity extraction means has passed an arbitrary number of sampling times. , a physical quantity upper limit value defined as the upper limit value of the physical quantity range, a physical quantity lower limit value defined as the lower limit value of the physical quantity range, and adjustment means for changing the interval between the physical quantity upper limit value and the physical quantity lower limit value according to the measured value of the physical quantity configured.

[0015] The physical quantity range detection means finds the physical quantity range with the highest density of the measured values of the physical quantity collected up to an arbitrary number of sampling times. Thereby, even when the normal operation range is unknown, the range of the physical quantity that has been normally operated with high precision can be specified. And even for pumps within the same normally operating range, the influence of gas load and temperature can be finely judged, so the operating status of each pump can be accurately grasped. Therefore, even for pumps that have been operating normally, an accurate overhaul judgment can be made. By changing the interval between the physical quantity upper limit value and the physical quantity lower limit value according to the measured value of the physical quantity, the range of the physical quantity in the usage situation can be narrowed down. That is, by making the threshold value of the physical quantity range variable instead of a fixed value, it is easy to narrow down the normal operation range.

[0018] Furthermore, in the present invention (claim 2 ), when the measured value of the physical quantity at the time of sampling is higher than the upper limit value within the physical quantity range, the physical quantity lower limit value is updated to be a certain amount higher, and when the measured value of the physical quantity at the time of sampling is lower than the lower limit value within the physical quantity range, the physical quantity upper limit value is updated to be lower by the certain amount.

[0019] Thereby, many physical quantities can be adjusted to fall within the physical quantity range.

[0020] Furthermore, in the present invention (claim 3 ), the certain amount is set based on the difference between the maximum expected value and the minimum expected value assumed from the measured value of the physical quantity.

[0021] Thereby, the certain amount can be accurately set according to the degree of asymptote.

[0022] Furthermore, in the present invention (claim 4 ), the physical quantity range asymptotically approaches a predetermined fixed value defined in advance.

[0023] By asymptotically approaching a predetermined fixed value defined as the expected variation for each physical quantity, the physical quantity range can be narrowed down to an accurate range.

[0024] Furthermore, in the present invention (claim 5) is configured to include a time acquisition means for acquiring a total time within the physical quantity range, which is the total time when the physical quantity belonged to the physical quantity range during the operation of the vacuum pump, and an operation total time which is the total time of the operation of the vacuum pump, and a display means for displaying the ratio of the total time within the physical quantity range to the total time within the physical quantity range or the operation total time.

[0025] By displaying the total time when the physical quantity belonged to the physical quantity range, or by displaying the ratio between this total time and the total time of the operation of the vacuum pump, the fatigue degree of the rotating blade can be easily judged.

[0026] Furthermore, the present invention (claim 6 ) is configured to include at least one threshold value set outside the physical quantity range, and an accumulation means for accumulating the time exceeding the threshold value, and a warning generation means for generating a warning when the time accumulated by the accumulation means exceeds a preset time.

[0027] It is possible to judge whether an overhaul is necessary from the cumulative value of the counted time, and to notify that an overhaul of the rotating blade is urged. By notifying a warning to urge an overhaul in this way, prevention of a rotating body breakage accident can be expected.

[0028] Furthermore, the present invention (claim 7 ) is characterized in that the sensor is a temperature measurement means for measuring the temperature of the rotating blade built in the vacuum pump body, or a current measurement means for measuring the amount of current flowing through the motor for driving the rotating blade.

[0029] The temperature measurement means and the current measurement means are used for the protection function processing of the pump. It can also be used for judging the timing of overhaul of the rotating blade in combination with the use as this protection function.

[0030] Furthermore, the present invention (claim 8) is a control device for a vacuum pump having a rotating blade built in a vacuum pump body and a sensor disposed in the vacuum pump body for measuring a physical quantity related to the rotating blade, the physical quantity extraction means for sampling and extracting the physical quantity measured by the sensor at predetermined time intervals during the operation of the vacuum pump, and the physical quantity range detection means for finding the physical quantity range having the highest density of the measured values of the physical quantity at each sampling up to that point when the extraction by the physical quantity extraction means has passed an arbitrary number of samplings. , a physical quantity upper limit value defined as the upper limit value of the physical quantity range, a physical quantity lower limit value defined as the lower limit value of the physical quantity range, and adjustment means for changing the interval between the physical quantity upper limit value and the physical quantity lower limit value according to the measured value of the physical quantity configured.

Effect of the Invention

[0031] As described above, according to the present invention (Claim 1), when the extraction by the physical quantity extraction means has passed an arbitrary number of samplings, the physical quantity range detection means for finding the physical quantity range having the highest density of the measured values of the physical quantity at each sampling up to that point is provided. Therefore, even when the normal operation range is unknown, the range of the physical quantity that has been normally operated can be specified with high accuracy. And even for pumps within the same normally operated range, the influence due to gas load and temperature can be judged in detail, so that the operating conditions of each pump can be accurately grasped. Therefore, even for a pump that has been operating normally, an accurate overhaul judgment can be made.

Brief Description of the Drawings

[0032]

Figure 1

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Figure 8

Figure 9

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Figure 12

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Figure 14

Figure 15

Mode for Carrying Out the Invention

[0033] Hereinafter, embodiments of the present invention will be described. A system configuration diagram regarding the determination of the necessity of rotating blade replacement, which is an embodiment of the present invention, is shown in FIG. 1, and a configuration diagram of a turbo molecular pump is shown in FIG. 2. In FIG. 1, the control device 200 is described separately from the turbo molecular pump 100, but the present embodiment can also be applied even if the turbo molecular pump 100 and the control device 200 are integrated.

[0034] The control device 200 is provided with a magnetic bearing control unit 3 that performs levitation control of the magnetic bearings (104, 105, 106) provided in the turbo molecular pump 100, and a motor drive control unit 5 that performs rotation control of the motor 121. The rotating blade temperature measurement unit 7 is adapted to receive a signal obtained by non-contact measurement of the temperature of the rotating body 103 by the rotating blade temperature sensor 9. The magnetic bearing control unit 3 outputs the levitation position and the like of the rotating body 103 and inputs them to the protection function processing unit 11. And in this protection function processing unit 11, when there is an abnormality in the levitation position and the like of the rotating body 103, a warning or pump stop is performed.

[0035] The motor drive control unit 5 outputs the rotation speed value and the motor current value of the rotating body 103 and inputs them to the protection function processing unit 11. The extraction of the motor current value of the rotating body 103 from the motor drive control unit 5 corresponds to physical quantity extraction means. And in the protection function processing unit 11, when there is an abnormality in the rotation speed value and the motor current value of the rotating body 103, a warning or pump stop is performed. Further, the motor current value output from the motor drive control unit 5 is input to the time count variable condition adjustment processing unit 13, and in this time count variable condition adjustment processing unit 13, the time during which the current value of the rotating body 103 remains within the range of the region is integrated for each region of the current value.

[0036] The rotating blade temperature measurement unit 7 outputs the rotating blade temperature value and inputs it to the protection function processing unit 11. The extraction of the rotating blade temperature value from the rotating blade temperature measurement unit 7 corresponds to physical quantity extraction means. And in this protection function processing unit 11, when there is an abnormality in the rotating blade temperature value, a warning or pump stop is performed. Further, the rotating blade temperature value output from the rotating blade temperature measurement unit 7 is input to the time count variable condition adjustment processing unit 13. And the average value of the sampled rotating blade temperature values is taken for one minute. Then, for each region of the rotating blade temperature value, the time during which the average value remains within the region is integrated. In the memory 15, each time value integrated by the time count variable condition adjustment processing unit 13 is stored. For example, in the recording processing unit 17, data is read from the memory 15 when the pump decelerates and stops, or every two hours, and is stored in the non-volatile memory 19. In the external output 21 such as an LCD, the calculation results for each area described later are displayed by an LCD display unit, an external device, or the like.

[0037] In FIG. 2, in the turbo molecular pump 100, an intake port 101 is formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127, a rotating body 103 is provided, in which a plurality of rotating blades 102 (102a, 102b, 102c...) that are turbine blades for sucking and exhausting gas are formed radially and in multiple stages on the circumferential part. A rotor shaft 113 is attached to the center of this rotating body 103, and this rotor shaft 113 is levitated and supported in the air and position-controlled by, for example, a magnetic bearing with five-axis control. The rotating body 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0038] The upper radial electromagnet 104 has four electromagnets arranged in pairs with respect to the X-axis and the Y-axis. Four upper radial sensors 107 are provided in proximity to the upper radial electromagnet 104 and corresponding to each of the upper radial electromagnets 104. As the upper radial sensor 107, for example, an inductance sensor having a conductive winding or an eddy current sensor is used, and the position of the rotor shaft 113 is detected based on the change in the inductance of this conductive winding that changes according to the position of the rotor shaft 113. This upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and send it to the control device 200.

[0039] In this control device 200, for example, a compensation circuit having a PID control function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in FIG. 3 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the radial position above the rotor shaft 113.

[0040] The rotor shaft 113 is formed of a high magnetic permeability material (such as iron or stainless steel) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. Further, the lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and the radial position below the rotor shaft 113 is adjusted in the same manner as the radial position above.

[0041] Furthermore, axial electromagnets 106A and 106B are arranged so as to sandwich a disk-shaped metal disk 111 provided at the lower part of the rotor shaft 113 from above and below. The metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and its axial position signal is configured to be sent to the control device 200.

[0042] In the control device 200, for example, a compensation circuit having a PID control function generates respective excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B respectively based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotor shaft 113 is adjusted.

[0043] In this way, the control device 200 appropriately adjusts the magnetic forces exerted by the axial electromagnets 106A and 106B on the metal disk 111, magnetically levitates the rotor shaft 113 in the axial direction, and holds it in space in a non-contact manner. Note that the amplifier circuit 150 for controlling the excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B will be described later.

[0044] On the other hand, the motor 121 includes a plurality of magnetic poles arranged circumferentially so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotationally drive the rotor shaft 113 via the electromagnetic force acting between the magnetic pole and the rotor shaft 113. Further, the motor 121 incorporates a rotational speed sensor such as a Hall element, a resolver, or an encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0045] Furthermore, for example, a phase sensor (not shown) is attached near the lower radial sensor 108 to detect the rotation phase of the rotor shaft 113. The control device 200 detects the position of the magnetic pole using both the detection signals of this phase sensor and the rotational speed sensor.

[0046] A plurality of fixed blades 123 (123a, 123b, 123c ···) are arranged with a slight gap from the rotary blades 102 (102a, 102b, 102c ···). The rotary blades 102 (102a, 102b, 102c ···) are each inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transfer the molecules of the exhaust gas downward by collision. The fixed blades 123 (123a, 123b, 123c ···) are made of a metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components.

[0047] Also, the fixed wing 123 is similarly formed by being inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and is alternately arranged with the stages of the rotary wing 102 toward the inside of the outer cylinder 127. And the outer peripheral end of the fixed wing 123 is supported in a state of being inserted between a plurality of stacked fixed wing spacers 125 (125a, 125b, 125c ···).

[0048] The fixed wing spacer 125 is a ring-shaped member and is made of, for example, a metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. The outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a slight gap therebetween. A base portion 129 is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. The exhaust gas that has entered the intake port 101 from the chamber (vacuum chamber) side and has been transferred to the base portion 129 is sent to the exhaust port 133.

[0049] Furthermore, depending on the application of the turbo molecular pump 100, a threaded spacer 131 is provided between the lower part of the fixed wing spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals as components, and a plurality of spiral threaded grooves 131a are engraved on its inner peripheral surface. The direction of the spiral of the threaded groove 131a is the direction in which the molecules of the exhaust gas are transferred toward the exhaust port 133 when they move in the rotation direction of the rotating body 103. A cylindrical portion 102d hangs down at the lowermost part following the rotary wings 102 (102a, 102b, 102c ···) of the rotating body 103. The outer peripheral surface of this cylindrical portion 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is close to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the threaded groove 131a by the rotary wing 102 and the fixed wing 123 is sent to the base portion 129 while being guided by the threaded groove 131a.

[0050] The base portion 129 is a disc-shaped member that constitutes the base of the turbo molecular pump 100 and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 physically holds the turbo molecular pump 100 and also functions as a heat conduction path, so it is desirable to use a metal with high rigidity and high thermal conductivity such as iron, aluminum, or copper.

[0051] In such a configuration, when the rotary blade 102 is rotationally driven by the motor 121 together with the rotor shaft 113, the exhaust gas is sucked from the chamber through the intake port 101 due to the action of the rotary blade 102 and the stationary blade 123. The rotational speed of the rotary blade 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotary blade 102 reaches 200 m / s to 400 m / s. The exhaust gas sucked from the intake port 101 passes between the rotary blade 102 and the stationary blade 123 and is transferred to the base portion 129. At this time, the temperature of the rotary blade 102 rises due to the frictional heat generated when the exhaust gas contacts the rotary blade 102 and the conduction of the heat generated by the motor 121. This heat is transferred to the stationary blade 123 side by radiation or conduction by the gas molecules of the exhaust gas.

[0052] The stationary blade spacer 125 is joined to each other at the outer peripheral portion and transfers heat received by the stationary blade 123 from the rotary blade 102 and frictional heat generated when the exhaust gas contacts the stationary blade 123 to the outside.

[0053] In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and the thread groove 131a is formed on the inner peripheral surface of the threaded spacer 131. However, conversely, there may be a case where a thread groove is formed on the outer peripheral surface of the cylindrical portion 102d and a spacer having a cylindrical inner peripheral surface is disposed around it.

[0054] Depending on the application of the turbo molecular pump 100, in order to prevent the gas sucked from the intake port 101 from entering the electrical components composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., the electrical components are covered by the stator column 122, and the inside of this stator column 122 may be maintained at a predetermined pressure with purge gas.

[0055] In this case, a pipe (not shown) is arranged in the base portion 129, and the purge gas is introduced through this pipe. The introduced purge gas is sent to the exhaust port 133 through the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner peripheral cylindrical portion of the rotating blade 102.

[0056] Here, the turbo molecular pump 100 requires control based on the identification of the model and the specific parameters adjusted individually (for example, various characteristics corresponding to the model). In order to store this control parameter, the turbo molecular pump 100 is provided with an electronic circuit unit 141 inside its main body. The electronic circuit unit 141 is composed of semiconductor memories such as EEP-ROM, electronic components such as semiconductor elements for accessing them, a substrate 143 for mounting them, etc. This electronic circuit unit 141 is housed below, for example, near the center of a rotation speed sensor (not shown) in the base portion 129 that constitutes the lower part of the turbo molecular pump 100, and is closed by an airtight bottom cover 145.

[0057] By the way, in the semiconductor manufacturing process, among the process gases introduced into the chamber, there are some that have the property of becoming solid when their pressure becomes higher than a predetermined value or their temperature becomes lower than a predetermined value. Inside the turbo molecular pump 100, the pressure of the exhaust gas is the lowest at the intake port 101 and the highest at the exhaust port 133. When the process gas is transferred from the intake port 101 to the exhaust port 133, if its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value, the process gas will become solid and adhere and deposit inside the turbo molecular pump 100.

[0058] For example, when SiCl is used as a process gas in an Al etching apparatus, when the pressure is low (760 [torr] to 10 4 [torr]) and the temperature is low (about 20 [°C]), it can be seen from the vapor pressure curve that solid products (e.g., AlCl -2 ) precipitate and adhere and deposit inside the turbo molecular pump 100. As a result, when deposits of the process gas accumulate inside the turbo molecular pump 100, these deposits narrow the pump flow path and cause a decrease in the performance of the turbo molecular pump 100. And the above-mentioned products were in a situation where they were likely to solidify and adhere at high-pressure parts near the exhaust port 133 and near the threaded spacer 131. 3 )

[0059] Therefore, in order to solve this problem, a heater 1 and an annular water-cooling pipe 149 are wound around the outer periphery of the base portion 129 and the like, and for example, a temperature sensor 3 (e.g., a thermistor) is embedded near the heater 1, and based on the signal of this temperature sensor 3, the temperature of the base portion 129 is maintained at a certain high temperature (set temperature), heating by the heater 1 and cooling by the water-cooling pipe 149 (hereinafter referred to as TMS. TMS; Temperature Management System) are carried out. A water-cooling valve (not shown) is provided in the water-cooling pipe 149 to control the cooling. However, in order to improve the efficiency of TMS, a heater (not shown) may be further provided at the exhaust port 133, and a temperature sensor (not shown) may be provided near this heater. A temperature sensor 5 corresponding to physical quantity extraction means is provided near the water-cooling pipe 149 of the base portion 129 to control the cooling. In addition, a rotor temperature sensor corresponding to physical quantity extraction means (not shown) for measuring the temperature of the rotating blades 102 is provided in the turbo molecular pump 100. And the temperature signal measured by this rotor temperature sensor is input to the control device 200. Also, the current value flowing through the motor 121 is measured and input to the control device 200.

[0060] Next, regarding the turbo molecular pump 100 configured as described above, an amplifier circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described. A circuit diagram of this amplifier circuit 150 is shown in FIG. 3.

[0061] In FIG. 3, one end of an electromagnet winding 151 that constitutes the upper radial electromagnet 104 or the like is connected to the positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to the negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs and have a structure in which a diode is connected between their source and drain.

[0062] At this time, for the transistor 161, the cathode terminal 161a of its diode is connected to the positive electrode 171a, and the anode terminal 161b is connected to one end of the electromagnet winding 151. Also, for the transistor 162, the cathode terminal 162a of its diode is connected to the current detection circuit 181, and the anode terminal 162b is connected to the negative electrode 171b.

[0063] On the other hand, a current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative electrode 171b. Similarly, a current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electric resistance element.

[0064] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, when the magnetic bearing is under 5-axis control and there are a total of 10 electromagnets 104, 105, 106A, and 106B, similar amplifier circuits 150 are configured for each of the electromagnets, and 10 amplifier circuits 150 are connected in parallel to the power supply 171.

[0065] Furthermore, the amplifier control circuit 191 is constituted by, for example, a digital signal processor section (hereinafter referred to as the DSP section) (not shown) of the control device 200, and this amplifier control circuit 191 is configured to switch the on / off of the transistors 161 and 162.

[0066] The amplifier control circuit 191 is configured to compare the current value detected by the current detection circuit 181 (a signal reflecting this current value is referred to as the current detection signal 191c) with a predetermined current command value. Then, based on this comparison result, the magnitudes of the pulse widths (pulse width times Tp1, Tp2) generated within the control cycle Ts, which is one cycle of PWM control, are determined. As a result, gate drive signals 191a and 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0067] During acceleration operation of the rotating body 103 when passing through the resonance point or when a disturbance occurs during constant speed operation, etc., it is necessary to control the position of the rotating body 103 with high speed and strong force. Therefore, as the power supply 171, a high voltage of about 50V, for example, is used so that a rapid increase (or decrease) in the current flowing through the electromagnet winding 151 can occur. Also, a normal capacitor is connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 for stabilizing the power supply 171 (not shown in the figure).

[0068] In such a configuration, when both of the transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as the electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0069] Also, when one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is retained. And by flowing the flywheel current through the amplifier circuit 150 in this way, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Further, by controlling the transistors 161 and 162 in this way, high-frequency noise such as harmonics generated in the turbo molecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnetic current iL flowing through the electromagnetic coil 151 can be detected.

[0070] That is, when the detected current value is smaller than the current command value, as shown in FIG. 4, both of the transistors 161 and 162 are turned on only once during the control cycle Ts (for example, 100 μs) for a time corresponding to the pulse width time Tp1. Therefore, during this period, the electromagnetic current iL increases toward the current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b through the transistors 161 and 162.

[0071] On the other hand, when the detected current value is larger than the current command value, as shown in FIG. 5, both of the transistors 161 and 162 are turned off only once during the control cycle Ts for a time corresponding to the pulse width time Tp2. Therefore, during this period, the electromagnetic current iL decreases toward the current value iLmin (not shown) that can be regenerated from the negative electrode 171b to the positive electrode 171a through the diodes 165 and 166.

[0072] And in any case, after the elapse of the pulse width times Tp1 and Tp2, one of the transistors 161 and 162 is turned on. Therefore, during this period, a flywheel current is retained in the amplifier circuit 150.

[0073] Next, the operation of this embodiment will be described. In this embodiment, an index is created that allows the degree of fatigue of the rotor 102 to be quantitatively and easily determined according to the operating conditions of the turbo molecular pump 100. This index is created for the current value of the motor 121 and the temperature of the rotor 102. The current value of the motor 121 and the temperature of the rotor 102 correspond to physical quantities. Fig. 6 shows the current value of the motor 121 and the temperature value of the rotor 102 divided into five stages, and the control method for each stage.

[0074] FIG. 7 shows an example of a time chart of the motor current value when this control method is applied. Graph 11 is the measured current value of motor 121. Graph 13 shows the condition variable value H, and graph 15 shows the condition variable value L. The condition variable value H corresponds to the upper physical quantity limit value, and the condition variable value L corresponds to the lower physical quantity limit value. FIG. 8 shows an example of a time chart of the rotor blade temperature value when this control method is applied. Graph 21 is the temperature value of rotor blade 102. As with FIG. 7, graph 13 shows the condition variable value H, and graph 15 shows the condition variable value L.

[0075] In Fig. 6, Fig. 7 and Fig. 8, region 1 is level 1 (L in the figure) that is above the abnormal threshold. V The level 2 (indicated by L in the figure) is above the warning threshold. V 2) is the warning notification stage, and area 3 is Level 3 (indicated in the figure) which is beyond the normal operating range. V 3), and area 4 is the normal operating level of level 4 (indicated by L V 4), and area 5 is level 5 (shown in the figure as L V The initial value of region 5 may be 0 amperes for the current value.

[0076] Next, a method will be described in which the control device 200 determines the degree of fatigue based on the temperature of the rotor blades 102. However, the current value of the motor 121 can be processed in the same manner. In FIG. 9, in step 1 (shown as S1 in the figure; hereinafter the same shall apply), the control device 200 starts processing the temperature of the rotary blade 102. In step 3, it is determined whether the measured temperature value belongs to the abnormal notification range. If it is determined that it belongs to the abnormal notification range, the process proceeds to step 5, and the count value of the counter at the rotary blade temperature level 1 is incremented by one. One count at this time is set to, for example, 1 minute (hereinafter the same shall apply). The case where it is determined that it belongs to this abnormal notification range corresponds to region 1 in FIGS. 6, 7, and 8. The counting process after it is determined that it belongs to this abnormal notification range is performed by the accumulation means belonging to the time count variable condition adjustment processing unit.

[0077] Thereafter, the process proceeds to step 7, and the processing of the normal operation range median value C adjustment subroutine is performed. In the normal operation range median value C adjustment subroutine in FIG. 10, the normal operation range median value C is the median of the condition variable value H and the condition variable value L. Then, in step 9, the value of this normal operation range median value C is recalculated using the current condition variable value H and the condition variable value L, and the result is updated. And the value of this newly calculated normal operation range median value C is used as the normal operation range median value C at the next sampling time. Thereafter, it returns in step 11 and proceeds to step 13 in FIG. 9.

[0078] In step 13, it returns to step 1 and waits in preparation for the processing at the next sampling time. The sampling interval is, for example, 1 minute. On the other hand, if it is determined in step 3 that the measured temperature value does not belong to the abnormal notification range, the process proceeds to step 15, and it is determined whether it belongs to the warning notification range. If it is determined in step 15 that it belongs to the warning notification range, the process proceeds to step 17, and the counter at the rotary blade temperature level 2 is incremented by one. The case where it is determined that it belongs to this warning notification range corresponds to region 2 in FIGS. 6, 7, and 8. Thereafter, the process proceeds to step 7, and the processing of the normal operation range median value C adjustment subroutine is performed.

[0079] On the other hand, in step 15, if it is determined that it does not belong to the warning notification area, the process proceeds to step 19, and it is determined whether it exceeds the normal operation area. Then, if it is determined in step 19 that it exceeds the normal operation area, the process proceeds to step 21, and the "wing temperature L V 3 count up, normal operation area upper limit H adjustment" subroutine operates. This case where it exceeds the normal operation area corresponds to area 3 in FIGS. 6, 7, and 8.

[0080] In the "wing temperature L V 3 count up, normal operation area upper limit H adjustment" subroutine shown in FIG. 11, at step 23, the count value of the counter at the rotating wing temperature level 3 is incremented by one. Then, at step 25, the conditional variable value H is updated by adding the adjustment increment δ. That is, in this case, in FIG. 6, the graph 13 showing the conditional variable value H is pulled up by the adjustment increment δ. That is, it is an adjustment to expand the normal operation area. The adjustment increment δ is defined, for example, like number 1, for each of the temperature value of the rotating wing 102 and the current value of the motor 121.

[0081] [Number 1] δ = (measured value maximum expected value - minimum expected value) / 10000

[0082] Here, the measured value maximum expected value is the maximum value of the temperature value or current value assumed as the measured value for the target turbo molecular pump 100, and the minimum expected value is the minimum value assumed as the measured value. In the case of the normal operation area median value C, the minimum expected value may be 0 amperes. Also, in the setting of number 1, it is assumed that the normal operation area median value C asymptotically approaches the average value of each of the temperature value of the rotating wing 102 and the current value of the motor 121 at 10,000 points. Thereafter, it returns at step 27 in FIG. 11. Thereafter, the process proceeds to step 7 in FIG. 9, and the process of the normal operation area median value C adjustment subroutine is performed.

[0083] On one hand, if it is determined in step 19 of FIG. 9 that the normal operating range has not been exceeded, the process proceeds to step 29, where it is determined whether it is within the normal operating range. If it is determined that it is within the normal operating range, the process proceeds to step 31, and the "wing temperature L V 4 count up, normal operating range H / L adjustment" subroutine operates. This normal operating range corresponds to region 4 in FIGS. 6, 7, and 8. As shown in FIGS. 7 and 8, the width and the position of the central value C of the normal operating range of region 4 vary with the passage of time.

[0084] In the "wing temperature L V 4 count up, normal operating range H / L adjustment" subroutine of FIG. 12, in step 33, it is determined whether the difference between the conditional variable value H and the conditional variable value L exceeds 2d. Here, d is the expected variation for each measured value, and it is set expecting that most of the measured values will finally converge within the range of +d and -d with respect to the central value C of the normal operating range as time passes. The physical quantity range detection means is configured to detect a state in which most of the measured values finally converge within the range of +d and -d with respect to the central value C of the normal operating range as such time passes.

[0085] When it is determined that the difference between the conditional variable value H and the conditional variable value L exceeds 2d, the process proceeds to step 35, and it is determined whether the measured value is C + d or more. In this case, since it can be determined that the measured value has appeared above the normal operating range central value C, the process proceeds to the "wing temperature L V 4,5 count up, upper adjustment above lower limit L" subroutine of step 37 for adjustment. In the "wing temperature L V 4,5 count up, upper adjustment above lower limit L" subroutine of FIG. 13, in step 39, the count value of the counter at the rotating wing temperature level 4 is incremented by 0.5. Then, in step 41, the count value of the counter at the rotating wing temperature level 5 is also incremented by 0.5. And in step 43, the conditional variable value L is updated in a form where it is incremented by the adjustment increment δ.

[0086] That is, in FIG. 7, the graph 15 showing the condition variable value L is pulled up by the adjustment increment δ. This is an adjustment to narrow the normal operation range. Thus, pulling up the condition variable value L by the adjustment increment δ is because it has been found that the measured value at this time is above the central value C of the normal operation range. When narrowing the convergence range, it can be determined that the range of region 4 may be narrowed by pulling up the lower graph 15. After that, the process returns at step 45 in FIG. 13.

[0087] Also, the reason for adding 0.5 to the counter values of the rotor blade temperature level 4 and the rotor blade temperature level 5 respectively is that when the measured value falls within the range of the adjustment increment δ as seen from the condition variable value L, it is appropriate to count the count value of the counter of the rotor blade temperature level 5. On the other hand, when the measured value does not fall within the range of the adjustment increment δ as seen from the condition variable value L, it is appropriate to count the count value of the counter of the rotor blade temperature level 4. The process returned at step 45 in FIG. 13 returns at step 47 in FIG. 12. After that, it proceeds to step 7 in FIG. 9, and the process of the normal operation range central value C adjustment subroutine is performed.

[0088] On the other hand, when it is determined at step 33 that the difference between the condition variable value H and the condition variable value L does not exceed 2d, the process proceeds to step 61. At step 61, the counter value of the counter of the rotor blade temperature level 4 is incremented by one. Then, the process returns at step 47. After that, it proceeds to step 7 in FIG. 9, and the process of the normal operation range central value C adjustment subroutine is performed. On the other hand, at step 35 in FIG. 12, when it is determined that the measured value is less than C + d, the process proceeds to step 49. At step 49, it is determined whether the measured value is less than C - d. And when the measured value is less than C - d, the process proceeds to the subroutine of "wing temperature L V 3,4 count up, upper limit H downward adjustment".

[0089] In FIG. 14, "wing temperature L VIn the "3, 4 count up, upper limit H downward adjustment" subroutine, in step 53, the counter value of the counter for the rotor blade temperature level 3 is incremented by 0.5. Then, in step 55, the counter value of the counter for the rotor blade temperature level 4 is also incremented by 0.5. And in step 57, the conditional variable value H is updated in a form that is decremented by the adjustment increment δ. That is, in FIG. 7, the graph 13 showing the conditional variable value H is pulled downward by the adjustment increment δ. This is an adjustment to narrow the normal operating range.

[0090] In this way, pulling down the conditional variable value H by the adjustment increment δ is because it is found that the measured value at this time is below the median value C of the normal operating range. When narrowing the convergence range, it can be determined that the range of region 4 may be narrowed by pulling down the upper graph 13. After that, it returns at step 59 in FIG. 14. Also, the reason for incrementing the counter values of the rotor blade temperature level 3 and the rotor blade temperature level 4 by 0.5 each is that when the measured value falls within the range of the adjustment increment -δ as seen from the conditional variable value H, it is appropriate to count the count value of the counter for the rotor blade temperature level 3, while when the measured value does not fall within the range of the adjustment increment -δ as seen from the conditional variable value H, it is appropriate to count the count value of the counter for the rotor blade temperature level 4.

[0091] The process that returns at step 59 in FIG. 14 returns at step 47 in FIG. 12. After that, it proceeds to step 7 in FIG. 7, and the process of the normal operating range median value C adjustment subroutine is performed. On the other hand, when it is determined at step 49 in FIG. 10 that the measured value is C - d or more, it proceeds to step 61, and the counter value of the counter for the rotor blade temperature level 2 is incremented by one. Then, it returns at step 47. After that, it proceeds to step 7 in FIG. 9, and the process of the normal operating range median value C adjustment subroutine is performed. That is, the median value C in the normal operation range is changed so as to converge to the average value of the temperature of the rotating blade 102 and the current of the motor 121. Specifically, it is changed so as to asymptotically approach the average value -d to the average value +d. Along with this, the time information is also accumulated for each region. The accumulation process of the time information for each region is performed by the time acquisition means belonging to the time count variable condition adjustment processing unit.

[0092] On the other hand, in step 29 of FIG. 9, when it is determined that it is not within the normal operation range, the process proceeds to step 63, and "wing temperature L" V 5 count up, normal operation range lower limit L adjustment" subroutine operates. The case where it is not within this normal operation range corresponds to region 5 in FIGS. 6, 7, and 8. As shown in FIG. 15, "wing temperature L" V In the "5 count up, normal operation range lower limit L adjustment" subroutine, in step 65, the counter value of the counter at the rotating blade temperature level 5 is incremented by one. Then, in step 67, the condition variable value L is updated by subtracting the adjustment increment δ. That is, in this case, in FIG. 7, the graph 15 showing the condition variable value L is pulled down by the adjustment increment δ. This is an adjustment to widen the normal operation range. The reason why the graph 15 is pulled down like this is that the measured value is below the graph 15. Then, it returns in step 69 of FIG. 15. After that, the process proceeds to step 7 of FIG. 9, and the process of the normal operation range median value C adjustment subroutine is performed.

[0093] FIG. 8 shows a time chart of the actual processing results for the temperature measurement values of the rotating blade. In this embodiment, the condition variable value H and the condition variable value L are changed. However, for comparison, the same pump was also verified simultaneously for the case where these are fixed. To calculate the residence time distribution, the values of the counters in regions 1 to 5 were summed, and the ratio of the value of each region's counter to the total value was calculated. As a result, the operating ratio for each region of the pump that had been operating for a long time was calculated. For example, when the condition variable value H and the condition variable value L were fixed values, the display was as follows: (region 1, region 2, region 3, region 4, region 5) = (0%, 0%, 97.4%, 2.3%, 0.3%). That is, when 10,000 cycles had elapsed, it could be determined that 97.4% of the measured temperature values shown in graph 21 belonged to the range of 90 degrees or more and 147 degrees at level 3.

[0094] On the other hand, when the condition variable value H (graph 13) and the condition variable value L (graph 15) were varied, the display could be as follows: (region 1, region 2, region 3, region 4, region 5) = (0%, 0%, 6.0%, 84.2%, 9.7%). That is, 84.2% belonged to region 4 in the range of 138 degrees or more and 146 degrees, and this range could be determined as the normal operating range. Thus, it can be seen that when the condition variable value H and the condition variable value L are varied, the operating status can be judged with higher accuracy compared to when they are fixed values. The results of the movable ratio for each region are displayed on an external output 21 such as an LCD corresponding to the display means, by an LCD display unit or an external device.

[0095] Through the above processing, as time passes, the normal operating range gradually converges to the range of the normal operating range median C - d to C + d. Therefore, it is possible to accurately know how many times or at what load the pump has been operating for each pump, and the operating status of the pump. Therefore, even if the pump is being used within the normal range, it becomes possible to determine how frequently it has been used at what temperature and motor current. For this reason, even if it has been used within the normal range during the operation period, in a situation where the temperature of the rotor 102 and the current of the motor 121 are concentrated on the high-frequency side within this normal range, it can be estimated that it is time to replace the pump. That is, even when the pump is operating normally, since region 4 can be judged in a converged form, it is possible to accurately judge the necessity of replacing the rotor 102 of the pump that has been operating normally.

[0096] Since the area has about five levels without making the levels too detailed and can be processed, little memory is required for data storage. In addition, in areas 1 and 2, warnings that prompt overhauls can also be notified, so prevention of rotating body damage accidents can be expected. Note that the present invention can be combined with various modifications and each embodiment without departing from the spirit of the present invention, and it is natural that the present invention also extends to such modifications and combinations.

Explanation of Signs

[0097] 3 Magnetic axis control unit 5 Motor drive control unit 7 Rotor temperature measurement unit 9 Rotor temperature sensor 11 Protection function processing unit 13 Time count variable condition adjustment processing unit 15 Memory 17 Recording processing unit 19 Non-volatile memory 21 External output such as LCD 100 Pump body 102 Rotor 103 Rotating body 104 Upper radial electromagnet 105 Lower radial electromagnet 106A, 106B Axial electromagnets 121 Motor 200 Control device

Claims

1. a rotating blade built into the vacuum pump body, and in a vacuum pump having a sensor disposed in the vacuum pump body for measuring a physical quantity related to the rotating blade, the vacuum pump has a physical quantity extraction means for sampling and extracting the physical quantity measured by the sensor at predetermined time intervals during operation of the vacuum pump; when the extraction by the physical quantity extraction means has passed an arbitrary number of samplings, it is provided with a physical quantity range detection means for finding the physical quantity range with the highest density of the measured values of the physical quantity at each sampling up to that point; a physical quantity upper limit value defined as the upper limit value of the physical quantity range, a physical quantity lower limit value defined as the lower limit value of the physical quantity range, and adjustment means for changing the interval between the physical quantity upper limit value and the physical quantity lower limit value according to the measured value of the physical quantity. The vacuum pump is characterized by this.

2. when the measured value of the physical quantity at the time of sampling is above the upper limit value within the physical quantity range, the physical quantity lower limit value is updated to be a certain amount higher, when the measured value of the physical quantity at the time of sampling is below the lower limit value within the physical quantity range, the physical quantity upper limit value is updated to be lower by the certain amount. The vacuum pump according to Claim 1 is characterized by this.

3. The vacuum pump according to Claim 2, wherein the certain amount is set based on the difference between the maximum expected value and the minimum expected value assumed from the measured value of the physical quantity.

4. The vacuum pump according to Claim 1, wherein the physical quantity range finally asymptotes to a predetermined fixed value defined in advance.

5. time acquisition means for acquiring a physical quantity range total time, which is the total time when the physical quantity belonged to the physical quantity range during operation of the vacuum pump, and an operation total time, which is the total time of operation of the vacuum pump; The vacuum pump according to Claim 1, further comprising display means for displaying the physical quantity range total time or the ratio of the physical quantity range total time to the operation total time.

6. at least one threshold value set outside the physical quantity range, accumulation means for accumulating the time exceeding the threshold value, and warning generation means for issuing a warning when the time accumulated by the accumulation means exceeds a preset time. The vacuum pump according to Claim 1 is characterized by this.

7. The vacuum pump according to claim 1, wherein the sensor is temperature measuring means for measuring the temperature of the rotating blade built in the vacuum pump body, or current measuring means for measuring the amount of current flowing through the motor for driving the rotating blade.

8. A rotating blade built in a vacuum pump body, A control device for a vacuum pump having a sensor disposed in the vacuum pump body and measuring a physical quantity related to the rotating blade, Physical quantity extraction means for sampling and extracting the physical quantity measured by the sensor at predetermined time intervals during operation of the vacuum pump, Physical quantity range detection means for finding the physical quantity range with the highest density of the measured values of the physical quantity at each sampling up to that point when the extraction by the physical quantity extraction means has passed an arbitrary number of samplings, A physical quantity upper limit value defined as the upper limit value of the physical quantity range, A physical quantity lower limit value defined as the lower limit value of the physical quantity range, A control device characterized by comprising adjustment means for changing the interval between the physical quantity upper limit value and the physical quantity lower limit value according to the measured value of the physical quantity.

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