Patent Publication Number: US-2023151826-A1

Title: Vacuum pump and controller

Description:
This application is a U.S. national phase application under 35 U.S.C. § 371 of international application number PCT/JP2021/025220 filed on Jul. 2, 2021, which claims the benefit of JP application number 2020-118497 filed on Jul. 9, 2020. The entire contents of each of international application number PCT/JP2021/025220 and JP application number 2020-118497 are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a vacuum pump and a controller. 
     BACKGROUND 
     A monitoring device of a certain vacuum pump (a) determines whether the vacuum pump is in a gas inflow state, based on changes over time in the motor current value and the rotational speed of the vacuum pump, and (b) records, in a storage portion, a base temperature data set that is collected in a predetermined cycle in a period in which the vacuum pump is in the gas inflow state (see Japanese Patent Application Publication No. 2017-194040, for example). 
     SUMMARY 
     The vacuum pump state information collected as described above may be used for cause analysis, and the like, when a failure occurs in the vacuum pump. 
     In general, the state information is stored in a specific storage region in a non-volatile memory. However, of the state information data periodically obtained, only a predetermined number of the latest state information data pieces are held in the non-volatile memory. As such, only the state of the vacuum pump in a time period of a specific length (the product of the collection cycle and the above-mentioned predetermined number) can be ascertained from the state information data that is held. This may hinder an appropriate cause analysis. That is, when the collection cycle is too short relative to the period in which an event occurs due to a certain cause, only part of the event may be ascertained. When the collection cycle is too long relative to the period in which an event occurs due to a certain cause, the ascertaining of the occurrence of the event itself may be failed, or only a fragment of the event may be ascertained. 
     As such, vacuum pump state information may not be collected in a timely manner. 
     In view of the foregoing problems, it is an object of the present disclosure to provide a vacuum pump and a controller with which vacuum pump state information is collected in a timely manner. 
     A vacuum pump according to the present disclosure includes: an internal device located in a vacuum pump main body; a control portion configured to control an operating state of the internal device; an information collection portion configured to collect state information of the vacuum pump main body; and a recording processing portion configured to record, in a non-volatile memory, the state information collected by the information collection portion. The information collection portion collects the state information of the vacuum pump main body at a point in time at which the operating state of the internal device is switched by the control portion. 
     A controller according to the present disclosure includes: a control portion configured to control an operating state of an internal device located in a vacuum pump main body; an information collection portion configured to collect state information of the vacuum pump main body; and a recording processing portion configured to record, in a non-volatile memory, the state information collected by the information collection portion. The information collection portion collects the state information of the vacuum pump main body at a point in time at which the operating state of the internal device is switched by the control portion. 
     The present disclosure provides a vacuum pump and a controller with which vacuum pump state information is collected in a timely manner. 
     The above and other objects, features, and advantages of the present disclosure will become further apparent from the following detailed description together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a vertical cross-sectional view of a turbomolecular pump according to an example of the present disclosure. 
         FIG.  2    is a circuit diagram of an amplifier circuit. 
         FIG.  3    is a time chart showing control performed when a current command value is greater than a detected value. 
         FIG.  4    is a time chart showing control performed when a current command value is less than a detected value. 
         FIG.  5    is a block diagram showing the configuration of a controller that controls the turbomolecular pump (vacuum pump) shown in  FIG.  1   . 
         FIG.  6    is a diagram illustrating an example of state transition of the turbomolecular pump (vacuum pump) shown in  FIG.  1   . 
         FIG.  7    is a diagram illustrating the information collection timing of the controller shown in  FIG.  5    (1/2). 
         FIG.  8    is a diagram illustrating the information collection timing of the controller shown in  FIG.  5    (2/2). 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, an example of the present disclosure is now described. 
       FIG.  1    is vertical cross-sectional view of a turbomolecular pump  100 . As shown in  FIG.  1   , the turbomolecular pump  100  includes a circular outer cylinder  127  having an inlet port  101  at its upper end. A rotating body  103  in the outer cylinder  127  includes a plurality of rotor blades  102  ( 102   a,    102   b,    102   c,  . . . ), which are turbine blades for gas suction and exhaustion, in its outer circumference section. The rotor blades  102  extend radially in multiple stages. The rotating body  103  has a rotor shaft  113  in its center. The rotor shaft  113  is suspended in the air and position-controlled by a magnetic bearing of 5-axis control, for example. 
     Upper radial electromagnets  104  include four electromagnets arranged in pairs on an X-axis and a Y-axis. Four upper radial sensors  107  are provided in close proximity to the upper radial electromagnets  104  and associated with the respective upper radial electromagnets  104 . Each upper radial sensor  107  may be an inductance sensor or an eddy current sensor having a conduction winding, for example, and detects the position of the rotor shaft  113  based on a change in the inductance of the conduction winding, which changes according to the position of the rotor shaft  113 . The upper radial sensors  107  are configured to detect a radial displacement of the rotor shaft  113 , that is, the rotating body  103  fixed to the rotor shaft  113 , and send it to the controller (not shown). 
     In the controller, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnets  104  based on a position signal detected by the upper radial sensors  107 . Based on this excitation control command signal, an amplifier circuit  150  (described below) controls and excites the upper radial electromagnets  104  to adjust a radial position of an upper part of the rotor shaft  113 . 
     The rotor shaft  113  may be made of a high magnetic permeability material (such as iron and stainless steel) and is configured to be attracted by magnetic forces of the upper radial electromagnets  104 . The adjustment is performed independently in the X-axis direction and the Y-axis direction. Lower radial electromagnets  105  and lower radial sensors  108  are arranged in a similar manner as the upper radial electromagnets  104  and the upper radial sensors  107  to adjust the radial position of the lower part of the rotor shaft  113  in a similar manner as the radial position of the upper part. 
     Additionally, axial electromagnets  106 A and  106 B are arranged so as to vertically sandwich a metal disc  111 , which has a shape of a circular disc and is provided in the lower part of the rotor shaft  113 . The metal disc  111  is made of a high magnetic permeability material such as iron. An axial sensor  109  is provided to detect an axial displacement of the rotor shaft  113  and send an axial position signal to the controller. 
     In the controller, the compensation circuit having the PID adjustment function may generate an excitation control command signal for each of the axial electromagnets  106 A and  106 B based on the signal on the axial position detected by the axial sensor  109 . Based on these excitation control command signals, the amplifier circuit  150  controls and excites the axial electromagnets  106 A and  106 B separately so that the axial electromagnet  106 A magnetically attracts the metal disc  111  upward and the axial electromagnet  106 B attracts the metal disc  111  downward. The axial position of the rotor shaft  113  is thus adjusted. 
     As described above, the controller appropriately adjusts the magnetic forces exerted by the axial electromagnets  106 A and  106 B on the metal disc  111 , magnetically levitates the rotor shaft  113  in the axial direction, and suspends the rotor shaft  113  in the air in a non-contact manner. The amplifier circuit  150 , which controls and excites the upper radial electromagnets  104 , the lower radial electromagnets  105 , and the axial electromagnets  106 A and  106 B, is described below. 
     The motor  121  includes a plurality of magnetic poles circumferentially arranged to surround the rotor shaft  113 . Each magnetic pole is controlled by the controller so as to drive and rotate the rotor shaft  113  via an electromagnetic force acting between the magnetic pole and the rotor shaft  113 . The motor  121  also includes a rotational speed sensor (not shown), such as a Hall element, a resolver, or an encoder, and the rotational speed of the rotor shaft  113  is detected based on a detection signal of the rotational speed sensor. 
     Furthermore, a phase sensor (not shown) is attached adjacent to the lower radial sensors  108  to detect the phase of rotation of the rotor shaft  113 . The controller detects the position of the magnetic poles using both detection signals of the phase sensor and the rotational speed sensor. 
     A plurality of stator blades  123   a,    123   b,    123   c,  . . . are arranged slightly spaced apart from the rotor blades  102  ( 102   a,    102   b,    102   c,  . . . ). Each rotor blade  102  ( 102   a,    102   b,    102   c,  . . . ) is inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft  113  in order to transfer exhaust gas molecules downward through collision. 
     The stator blades  123  are also inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft  113 . The stator blades  123  extend inward of the outer cylinder  127  and alternate with the stages of the rotor blades  102 . The outer circumference ends of the stator blades  123  are inserted between and thus supported by a plurality of layered stator blade spacers  125  ( 125   a,    125   b,    125   c,  . . . ). 
     The stator blade spacers  125  are ring-shaped members made of a metal, such as aluminum, iron, stainless steel, or copper, or an alloy containing these metals as components, for example. The outer cylinder  127  is fixed to the outer circumferences of the stator blade spacers  125  with a slight gap. A base portion  129  is located at the base of the outer cylinder  127 . The base portion  129  has an outlet port  133  providing communication to the outside. The exhaust gas transferred to the base portion  129  is then sent to the outlet port  133 . 
     According to the application of the turbomolecular pump  100 , a threaded spacer  131  may be provided between the lower part of the stator blade 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, or iron, or an alloy containing these metals as components. The threaded spacer  131  has a plurality of helical thread grooves  131   a  in its inner circumference surface. When exhaust gas molecules move in the rotation direction of the rotating body  103 , these molecules are transferred toward the outlet port  133  in the direction of the helix of the thread grooves  131   a.  In the lowermost section of the rotating body  103  below the rotor blades  102  ( 102   a,    102   b,    102   c,  . . . ), a cylindrical portion  102   d  extends downward. The outer circumference surface of the cylindrical portion  102   d  is cylindrical and projects toward the inner circumference surface of the threaded spacer  131 . The outer circumference surface is adjacent to but separated from the inner circumference surface of the threaded spacer  131  by a predetermined gap. The exhaust gas transferred to the thread grooves  131   a  by the rotor blades  102  and the stator blades  123  is guided by the thread grooves  131   a  to the base portion  129 . 
     The base portion  129  is a disc-shaped member forming the base section of the turbomolecular pump  100 , and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion  129  physically holds the turbomolecular pump  100  and also serves as a heat conduction path. As such, the base portion  129  is preferably made of rigid metal with high thermal conductivity, such as iron, aluminum, or copper. 
     In this configuration, when the motor  121  drives and rotates the rotor blades  102  together with the rotor shaft  113 , the interaction between the rotor blades  102  and the stator blades  123  causes the suction of exhaust gas from the chamber through the inlet port  101 . The exhaust gas taken through the inlet port  101  moves between the rotor blades  102  and the stator blades  123  and is transferred to the base portion  129 . At this time, factors such as the friction heat generated when the exhaust gas comes into contact with the rotor blades  102  and the conduction of heat generated by the motor  121  increase the temperature of the rotor blades  102 . This heat is conducted to the stator blades  123  through radiation or conduction via gas molecules of the exhaust gas, for example. 
     The stator blade spacers  125  are joined to each other at the outer circumference portion and conduct the heat received by the stator blades  123  from the rotor blades  102 , the friction heat generated when the exhaust gas comes into contact with the stator blades  123 , and the like to the outside. 
     In the above description, the threaded spacer  131  is provided at the outer circumference of the cylindrical portion  102   d  of the rotating body  103 , and the thread grooves  131   a  are engraved in the inner circumference surface of the threaded spacer  131 . However, this may be inversed in some cases, and a thread groove may be engraved in the outer circumference surface of the cylindrical portion  102   d,  while a spacer having a cylindrical inner circumference surface may be arranged around the outer circumference surface. 
     According to the application of the turbomolecular pump  100 , to prevent the gas drawn through the inlet port  101  from entering an electrical portion, which includes the upper radial electromagnets  104 , the upper radial sensors  107 , the motor  121 , the lower radial electromagnets  105 , the lower radial sensors  108 , the axial electromagnets  106 A,  106 B, and the axial sensor  109 , the electrical portion may be surrounded by a stator column  122 . The inside of the stator column  122  may be maintained at a predetermined pressure by purge gas. 
     In this case, the base portion  129  has a pipe (not shown) through which the purge gas is introduced. The introduced purge gas is sent to the outlet port  133  through gaps between a 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 circumference cylindrical portion of the rotor blade  102 . 
     The turbomolecular pump  100  may use the identification of the model and control based on individually adjusted unique parameters (for example, various characteristics associated with the model). To store these control parameters, the turbomolecular pump  100  includes an electronic circuit portion  141  in its main body. The electronic circuit portion  141  may include a semiconductor memory, such as an EEPROM, electronic components such as semiconductor elements for accessing the semiconductor memory, and a substrate  143  for mounting these components. The electronic circuit portion  141  is housed under a rotational speed sensor (not shown) near the center, for example, of the base portion  129 , which forms the lower part of the turbomolecular pump  100 , and is closed by an airtight bottom lid  145 . 
     Some process gas introduced into the chamber in the manufacturing process of semiconductors has the property of becoming solid when its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value. In the turbomolecular pump  100 , the pressure of the exhaust gas is lowest at the inlet port  101  and highest at the outlet port  133 . When the pressure of the process gas increases beyond a predetermined value or its temperature decreases below a predetermined value while the process gas is being transferred from the inlet port  101  to the outlet port  133 , the process gas is solidified and adheres and accumulates on the inner side of the turbomolecular pump  100 . 
     For example, when SiCl 4  is used as the process gas in an Al etching apparatus, according to the vapor pressure curve, a solid product (for example, AlCl 3 ) is deposited at a low vacuum (760 [torr] to 10 −2  [torr]) and a low temperature (about 20 [° C.]) and adheres and accumulates on the inner side of the turbomolecular pump  100 . When the deposit of the process gas accumulates in the turbomolecular pump  100 , the accumulation may narrow the pump flow passage and degrade the performance of the turbomolecular pump  100 . The above-mentioned product tends to solidify and adhere in areas with higher pressures, such as the vicinity of the outlet port and the vicinity of the threaded spacer  131 . 
     To solve this problem, conventionally, a heater or annular water-cooled tube  149  (not shown) is wound around the outer circumference of the base portion  129 , and a temperature sensor (e.g., a thermistor, not shown) is embedded in the base portion  129 , for example. The signal of this temperature sensor is used to perform control to maintain the temperature of the base portion  129  at a constant high temperature (preset temperature) by heating with the heater or cooling with the water-cooled tube  149  (hereinafter referred to as TMS (temperature management system)). 
     The amplifier circuit  150  is now described that controls and excites the upper radial electromagnets  104 , the lower radial electromagnets  105 , and the axial electromagnets  106 A and  106 B of the turbomolecular pump  100  configured as described above.  FIG.  2    is a circuit diagram of the amplifier circuit. 
     In  FIG.  2   , one end of an electromagnet winding  151  forming an upper radial electromagnet  104  or the like is connected to a positive electrode  171   a  of a power supply  171  via a transistor  161 , and the other end is connected to a negative electrode  171   b  of the power supply  171  via a current detection circuit  181  and a transistor  162 . Each transistor  161 ,  162  is a power MOSFET and has a structure in which a diode is connected between the source and the drain thereof. 
     In the transistor  161 , a cathode terminal  161   a  of its diode is connected to the positive electrode  171   a,  and an anode terminal  161   b  is connected to one end of the electromagnet winding  151 . In the transistor  162 , a cathode terminal  162   a  of its diode is connected to a current detection circuit  181 , and an anode terminal  162   b  is connected to the negative electrode  171   b.    
     A diode  165  for current regeneration has a cathode terminal  165   a  connected to one end of the electromagnet winding  151  and an anode terminal  165   b  connected to the negative electrode  171   b.  Similarly, a diode  166  for current regeneration has a cathode terminal  166   a  connected to the positive electrode  171   a  and an anode terminal  166   b  connected to the other end of the electromagnet winding  151  via the current detection circuit  181 . The current detection circuit  181  may include a Hall current sensor or an electric resistance element, for example. 
     The amplifier circuit  150  configured as described above corresponds to one electromagnet. Accordingly, when the magnetic bearing uses 5-axis control and has ten electromagnets  104 ,  105 ,  106 A, and  106 B in total, an identical amplifier circuit  150  is configured for each of the electromagnets. These ten amplifier circuits  150  are connected to the power supply  171  in parallel. 
     An amplifier control circuit  191  may be formed by a digital signal processor portion (not shown, hereinafter referred to as a DSP portion) of the controller. The amplifier control circuit  191  switches the transistors  161  and  162  between on and off. 
     The amplifier control circuit  191  is configured to compare a current value detected by the current detection circuit  181  (a signal reflecting this current value is referred to as a current detection signal  191   c ) with a predetermined current command value. The result of this comparison is used to determine the magnitude of the pulse width (pulse width time Tp 1 , Tp 2 ) generated in a control cycle Ts, which is one cycle in PWM control. As a result, gate drive signals  191   a  and  191   b  having this pulse width are output from the amplifier control circuit  191  to gate terminals of the transistors  161  and  162 . 
     Under certain circumstances such as when the rotational speed of the rotating body  103  reaches a resonance point during acceleration, or when a disturbance occurs during a constant speed operation, the rotating body  103  may benefit from positional control at high speed and with a strong force. For this purpose, a high voltage of about 50 V, for example, is used for the power supply  171  to enable a rapid increase (or decrease) in the current flowing through the electromagnet winding  151 . Additionally, a capacitor is generally connected between the positive electrode  171   a  and the negative electrode  171   b  of the power supply  171  to stabilize the power supply  171  (not shown). 
     In this configuration, when both transistors  161  and  162  are turned on, the current flowing through the electromagnet winding  151  (hereinafter referred to as an electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases. 
     Also, when one of the transistors  161  and  162  is turned on and the other is turned off, a freewheeling current is maintained. Passing the freewheeling current through the amplifier circuit  150  in this manner reduces the hysteresis loss in the amplifier circuit  150 , thereby limiting the power consumption of the entire circuit to a low level. Moreover, by controlling the transistors  161  and  162  as described above, high frequency noise, such as harmonics, generated in the turbomolecular pump  100  can be reduced. Furthermore, by measuring this freewheeling current with the current detection circuit  181 , the electromagnet current iL flowing through the electromagnet winding  151  can be detected. 
     That is, when the detected current value is smaller than the current command value, as shown in  FIG.  3   , the transistors  161  and  162  are simultaneously on only once in the control cycle Ts (for example, 100 μs) for the time corresponding to the pulse width time Tp 1 . During this time, the electromagnet current iL increases accordingly toward the current value iLmax (not shown) that can be passed from the positive electrode  171   a  to the negative electrode  171   b  via the transistors  161  and  162 . 
     When the detected current value is larger than the current command value, as shown in  FIG.  4   , the transistors  161  and  162  are simultaneously off only once in the control cycle Ts for the time corresponding to the pulse width time Tp 2 . During this time, the electromagnet current iL decreases accordingly toward the current value iLmin (not shown) that can be regenerated from the negative electrode  171   b  to the positive electrode  171   a  via the diodes  165  and  166 . 
     In either case, after the pulse width time Tp 1 , Tp 2  has elapsed, one of the transistors  161  and  162  is on. During this period, the freewheeling current is thus maintained in the amplifier circuit  150 . 
     The turbomolecular pump  100  described above is an example of a vacuum pump. The controller described above has functions described below.  FIG.  5    is a block diagram showing the configuration of a controller  200  that controls the turbomolecular pump (vacuum pump) shown in  FIG.  1   . 
     The controller  200  shown in  FIG.  5    includes a magnetic bearing control portion  201 , a motor drive control portion  202 , a temperature measurement portion  203 , an output control portion  204 , a counter portion  205 , a protection function processing portion  206 , an information collection portion  207 , a recording processing portion  208 , a non-volatile memory  209 , an interface processing portion  210 , a display device  211 , and an interface  212 . 
     The magnetic bearing control portion  201  electrically controls the operating state of the magnetic bearing of the rotor shaft  113  (the upper radial electromagnets  104 , the lower radial electromagnets  105 , the axial electromagnets  106 A and  106 B, the upper radial sensors  107 , the lower radial sensors  108 , and the axial sensor  109 ) to adjust the radial and axial position of the rotor shaft  113  as described above. 
     The motor drive control portion  202  electrically controls the operating state of the motor  121  and rotates the motor  121  at a predetermined rotational speed. 
     The temperature measurement portion  203  is a temperature sensor for the TMS described above and measures the temperature of the location where the temperature sensor is arranged. Specifically, the temperature measurement portion  203  identifies the temperature of that location based on the output signal of the temperature sensor. 
     The output control portion  204  electrically controls the operating states of output devices for the TMS, such as the above-mentioned heater and a valve of the water-cooled tube  149  (cooling valve). The heater is turned on/off, and the cooling valve is opened/closed such that the temperature at the location where the temperature sensor is located is a predetermined temperature. 
     The counter portion  205  counts the time elapsed since activating the vacuum pump or the actual time. The counter portion  205  may be a timer that counts up the elapsed time, a real-time clock, or the like. 
     The protection function processing portion  206  obtains state information of the vacuum pump from the magnetic bearing control portion  201 , the motor drive control portion  202 , the temperature measurement portion  203 , and the like. In case of an abnormality of the vacuum pump, the protection function processing portion  206  detects the abnormality based on the state information. 
     The state information includes the heater temperature, the cooling temperature, the temperatures of different portions such as rotor blades, the rotational speed (number of revolutions) of the motor  121 , heater on/off state, cooling valve open/closed state, and the like. 
     The information collection portion  207  collects, from the protection function processing portion  206 , state information of specific points in time from the state information of the vacuum pump main body obtained by the protection function processing portion  206 . 
     Specifically, the information collection portion  207  collects the state information of the vacuum pump main body at the point in time when a control portion (such as the output control portion  204  or the motor drive control portion  202 ) that controls the operating state of an internal device (such as the TMS output device or the motor  121 ) located in the vacuum pump main body switches the operating state of the internal device. 
     Thus, in this example, the internal device includes a temperature management device (i.e., the TMS output device described above), and the temperature management device includes at least one of a heater and a cooling valve. Also, in this example, the internal device includes a power system device, and the power system device includes at least one of the motor  121  and a magnetic bearing. 
     In particular, the information collection portion  207  of the present example collects the state information of the vacuum pump main body at activation of the vacuum pump as the initial values of the state information. Specifically, a self-diagnostic process is performed immediately after the vacuum pump is activated, and the information collection portion  207  collects the state information of the vacuum pump main body at the time of performing the self-diagnostic process as the initial values of the state information. This allows the number of power-on times (that is, the number of activation times) to be identified from the state information recorded in the non-volatile memory  209 . 
     Additionally, the information collection portion  207  of the present example monitors, from activation of the vacuum pump, whether the operating state of an internal device is switched by a control portion and, instead of periodically collecting the state information of the vacuum pump main body, collects the state information of the vacuum pump main body at the point in time when the operating state of an internal device is switched by a control portion. 
     The recording processing portion  208  records the state information collected by the information collection portion  207  in a built-in non-volatile memory  209 . At this time, time information indicating the point in time when the state information is collected is recorded together with the state information. The time information is obtained by the counter portion  205 . The non-volatile memory  209  may be a flash memory or other non-volatile memory. Specifically, the recording processing portion  208  (a) records the state information in a storage region of a predetermined size in the non-volatile memory  209 , and (b) uses the storage region as a ring buffer to record the state information. That is, the state information of one point in time is stored as one data set in one buffer region of a predetermined number of buffer regions in the ring buffer. After all of the predetermined number of buffer regions store state information data sets, the oldest state information data set is overwritten with the latest state information data set. 
     The interface processing portion  210  displays the state information of the vacuum pump main body obtained by the protection function processing portion  206  on the display device  211 , reads out the state information stored in the non-volatile memory  209 , and outputs it to the outside through the interface  212 . 
     The display device  211  includes an indicator such as an LED, a liquid crystal display, and the like, and displays various types of information to the user. The interface  212  performs data communication with an external terminal device through serial communication or the like according to a predetermined communication standard. 
     The operation of the vacuum pump is now described. 
       FIG.  6    is a diagram illustrating an example of state transition of the turbomolecular pump (vacuum pump) shown in  FIG.  1   . For example, as shown in  FIG.  6   , when the power is turned on, the controller  200  performs a predetermined self-diagnostic process. When the self-diagnostic process is completed, the magnetic bearing control portion  201  controls the magnetic bearing to place the vacuum pump in a stationary levitation state. Subsequently, when the operation of the vacuum pump is started, the motor drive control portion  202  starts controlling the motor  121  to accelerate the motor  121 , thereby bringing the vacuum pump into an acceleration operating state. When the rotational speed of the vacuum pump reaches a permissible range, the motor drive control portion  202  places the vacuum pump into a rated operating state. Then, the motor drive control portion  202  appropriately places the vacuum pump into an acceleration operating state or a deceleration operating state so that the rotational speed of the vacuum pump is within the permissible range (that is, the rated operating state is maintained). At the end of the operation, the motor drive control portion  202  places the vacuum pump into a deceleration operating state, and when the rotation of the motor  121  is no longer detected, the vacuum pump transitions to a stationary levitation state. Also, when the rotation of the motor is detected while the vacuum pump is not operating, the motor drive control portion  202  places the vacuum pump into a deceleration operating state, and when the rotation of the motor  121  is no longer detected, the vacuum pump transitions to a stationary levitation state. 
     In this manner, when the vacuum pump is in operation, control is performed to switch the operating state of the motor  121  to maintain the rated operating state. Additionally, the amount of heat generated by the motor  121  changes with the load of the motor  121  and the flow rate of the gas, for example, and the environmental temperature also changes. As such, the temperature management of the gas flow passage is dynamically performed by the TMS described above. 
     The protection function processing portion  206  periodically obtains state information from the magnetic bearing control portion  201 , the motor drive control portion  202 , the temperature measurement portion  203 , and the like, and monitors whether an abnormality has occurred in the vacuum pump. 
     The information collection portion  207  detects a point in time when the control of the magnetic bearing control portion  201 , the motor drive control portion  202 , the output control portion  204 , or the like is switched. Upon detecting a switching time point, the information collection portion  207  collects the state information of specific items together with the time information indicating the switching time point from the protection function processing portion  206  and records the information in the non-volatile memory  209  using the recording processing portion  208 . The time information is provided by the counter portion 
       FIGS.  7  and  8    are diagrams illustrating the information collection timing of the controller shown in  FIG.  5   .  FIG.  7    is a diagram illustrating the information collection timing at activation of the vacuum pump.  FIG.  8    is a diagram illustrating the information collection timing during operation of the vacuum pump. 
     For example, as shown in  FIG.  7   , after the vacuum pump is activated, the output control portion  204  turns on the heater and closes the cooling valve. This increases the heater temperature (the detected value of the temperature sensor corresponding to the heater) and the cooling temperature (the detected value of the temperature sensor corresponding to the cooling valve). 
     The output control portion  204  turns off the heater when the heater temperature exceeds a predetermined target temperature, and then turns on the heater when the heater temperature falls below the predetermined target temperature. The output control portion  204  thus controls the heater so that the heater temperature is maintained at the predetermined target temperature. In  FIG.  7   , at points in time t 11 , t 13 , t 15 , t 17 , t 19 , t 21 , t 23 , and t 25 , the operating state of the heater is switched from the ON state to the OFF state, and at points in time t 12 , t 14 , t 16 , t 18 , t 20 , t 22 , t 24 , and t 26 , the operating state of the heater is switched from the OFF state to the ON state. 
     The output control portion  204  opens the cooling valve when the cooling temperature exceeds a predetermined target temperature, and then closes the cooling valve when the cooling temperature falls below the predetermined target temperature. The output control portion  204  thus controls the cooling valve so that the cooling temperature is maintained at the predetermined target temperature. In  FIG.  7   , at points in time t 41 , t 43 , t 45 , t 47 , t 49 , t 51 , t 53 , t 55 , t 57 , and t 59 , the operating state of the cooling valve is switched from the closed state to the open state, and at points in time t 42 , t 44 , t 46 , t 48 , t 50 , t 52 , t 54 , t 56 , t 58 , and t 60 , the operating state of the cooling valve is switched from the open state to the closed state. 
     The information collection portion  207  monitors, from activation of the vacuum pump, whether the operating state of the TMS output device or a power system device, such as the motor  121 , is switched and, instead of periodically collecting the state information of the vacuum pump main body, collects the state information of the vacuum pump main body at the point in time when the operating state of an internal device is switched. The information collection portion  207  records this information in the non-volatile memory  209  using the recording processing portion  208 . 
     Accordingly, in the example shown in  FIG.  7   , the information collection portion  207  collects the state information of the vacuum pump main body at points in time t 11  to t 26  and t 41  to t 60  and records the information in the non-volatile memory  209  using the recording processing portion  208 . For example, as shown in  FIG.  7   , state information is not recorded in the non-volatile memory  209  before the heater temperature or the cooling temperature reaches the target temperature after activation. 
     After the control of the motor  121  starts, the state information of the vacuum pump main body is collected at the point in time when the motor operating state is switched between acceleration operation, rated operation, and deceleration operation. The state information is recorded by the recording processing portion  208  in the non-volatile memory  209 . 
     As such, in the example shown in  FIG.  8   , in addition to points in time t 71  to t 76  at which the heater operating state is switched and points in time t 81  to t 92  at which the cooling valve operating state is switched, the information collection portion  207  also collects the state information of the vacuum pump main body at the point in time when the motor operating state is switched, and records the information in the non-volatile memory  209  using the recording processing portion  208 . Similarly, the state information is collected and recorded when the operating state of the magnetic bearing is switched between the stationary levitation state and the touchdown state. 
     The state information stored in the non-volatile memory  209  in this manner is read out to an external device via the interface  212  and the interface processing portion  210 , and is used to analyze the cause of a failure of the vacuum pump, for example. 
     As described above, according to the above example, the control portions  201 ,  202 , and  204  control the operating states of internal devices (such as the motor  121 , heater, and cooling valve) located in the vacuum pump main body. The information collection portion  207  collects the state information of the vacuum pump main body, and the recording processing portion  208  records the state information collected by the information collection portion  207  in the non-volatile memory  209 . Also, the information collection portion  207  collects the state information of the vacuum pump main body at the point in time when the control portion  201 ,  202 ,  204  switches the operating state of an internal device. 
     Accordingly, the state information of the vacuum pump is collected in a timely manner. As a result, even when the storage region for the state information in the non-volatile memory  209  is not large, the analysis of the cause of failure is likely to be smoothly performed. 
     Various alterations and modifications to the above-described examples will be apparent to those skilled in the art. Such alterations and modifications may be made without departing from the spirit and scope of the subject matter and without compromising the intended advantages. That is, such alterations and modifications are intended to be within the scope of the claims. 
     For example, in the above example, the information collection portion  207  collects all the state information of a plurality of specific items in response to switching of the operating state of any one of a plurality of internal devices. Alternatively, in response to switching of the operating state of any one of the internal devices, the state information of only some of the specific items corresponding to the internal device whose operating state has been switched may be collected. 
     Furthermore, in the example described above, when an information collection time point (switching of the operating state of an internal device) is detected within a predetermined time after state information is recorded in the non-volatile memory  209 , the state information does not have to be recorded in the non-volatile memory  209 . 
     The present is applicable to vacuum pumps, for example.