JP2008157439A - Magnetic bearing device and compressor for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing device capable of securing a stable motion with no risk of a rotary main shaft making contact with other parts even if the rotary main shaft has made a thermal expansion due to a temperature rise in association with its high-speed rotation etc. and to provide a compressor for fuel cell capable of establishing stable motions using the magnetic bearing device. <P>SOLUTION: The magnetic bearing device is equipped with a pair of front and rear axial magnetic bearings 21 and 22 to support a rotor in the non-contact condition in the axial direction. The arrangement further includes a thermistor type temperature sensor 20 as a temperature presuming means to presume the surface temperature of the rotor and a controller 202 as an electromagnet type controlling means for controlling the position in the axial direction of the rotor by regulating the exciting current to be fed to the electromagnets of the magnetic bearings 21 and 22 on the basis of the surface temperature presumed by the temperature sensor 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic bearing device that includes a plurality of pairs of magnetic bearings and supports a rotary main shaft in a non-contact state in an axial direction or a radial direction and magnetically levitates, and a fuel cell compressor using the magnetic bearing device.

  Conventionally, as a magnetic bearing device, a plurality of pairs of axial electromagnets or radial directions (radial directions) supporting a rotor (rotary main shaft) integrally provided with a flange portion in a non-contact state in the axial direction (axial direction) of the rotor. Magnetic bearings with multiple pairs of radial electromagnets supported in a non-contact state (a pair of magnetic bearings are provided for each of the axial and radial directions), and position detection signals by detecting the axial and radial positions of the rotor There is known a position detection means for outputting a signal and an electromagnet control means for controlling each electromagnet of a magnetic bearing based on the position detection signal (see Patent Document 1).

  Such a magnetic bearing device is provided with one axial position sensor facing the axial end face of the rotor as position detecting means for detecting the position in the axial direction, and position detecting means for detecting the radial position. Are provided with a plurality of pairs of radial position sensors arranged so as to sandwich the rotor from both sides in two radial directions orthogonal to each other.

  The electromagnet control means outputs an electromagnet control signal based on the target floating position signal of the rotor and the position detection signal, and based on the electromagnet control signal output from the electromagnet control signal output section. An electromagnet driving unit for driving the electromagnet is provided.

  The electromagnet control signal output unit outputs an excitation current signal as an electromagnet control signal for each electromagnet of the magnetic bearing, and the electromagnet drive unit outputs an excitation current proportional to the excitation current signal to each electromagnet of the magnetic bearing. Supply. Here, the excitation current signal for each electromagnet is a combination of the steady current signal and the control current signal, and the excitation current supplied to each electromagnet is the combination of the steady current and the control current. The steady current value (steady current signal value) is constant regardless of the position of the rotor in the axial direction and the radial direction, and the control current value (control current signal value) varies depending on the position of the rotor in the axial direction and the radial direction. . And about each pair of magnetic bearing in an axial direction and radial direction, the absolute value of a control current value (control current signal value) is mutually equal, and the code | symbol is mutually reverse.

  In the magnetic bearing device described above, the axial and radial mechanical center positions with respect to the movable range of the rotor, the axial and radial magnetic center positions with respect to the positions of the electromagnets of the magnetic bearing, and the position of the position sensor. There is a center position with respect to the sensor.

  Here, the mechanical center position is a center position of a movable range regulated by a protective bearing such as a so-called touchdown bearing. The magnetic center position in the axial direction and the radial direction is the position of the center of the two electromagnets paired in the axial direction and the radial direction. The center position of the pair of sensors in the axial direction is a reference position where the distance between the end surface for detecting the position of the rotor and the axial position sensor is a predetermined value set in advance. In addition, the center position of the pair of sensors in the radial direction is the center position of the two radial position sensors paired in the radial direction.

  Generally, the magnetic bearing device is designed so that the above-described mechanical center position, magnetic center position, and sensor center position all coincide. In the magnetic bearing device, each electromagnet of the magnetic bearing is controlled by the electromagnet control means so that the rotor is held at the center position of the sensor, that is, the center of the rotor coincides with the center position of the sensor. Therefore, the rotor is held at the magnetic center position. When the rotor is thus held at the magnetic center position, the distance between the pair of magnetic bearings and the rotor in the axial direction or the radial direction is substantially the same.

A fuel equipped with a magnetic bearing device mounted on a vehicle such as an automobile using a fuel cell and having an impeller and a rotor (rotary main shaft) that supports the impeller so as to supply compressed air to the fuel cell. A battery compressor is known (Patent Document 2). In this fuel cell compressor, a pressure volute that is pressurized by rotation of the impeller to generate compressed air inside and also serves as a passage for discharging the compressed air to the outside is provided near the tip of the impeller. .
Japanese Unexamined Patent Publication No. 2000-145775, FIG. 1, etc. Japanese Patent Laid-Open No. 2004-301225, FIG.

  In such a fuel cell compressor, with the high-speed rotation of the rotor of the magnetic bearing device, the stator coil that mainly drives the rotor to generate heat generates heat, and the rotor and the rotor in the housing that houses the stator coil are transmitted to heat the rotor. . Then, the rotor expands axially on the impeller side due to thermal expansion due to the temperature rise, and the separation distance between the impeller and the pressure volute gradually decreases, and finally the two come into contact with each other and the impeller is seriously damaged. was there.

  In addition to such fuel cell compressor applications, in the above-described magnetic bearing device, the rotor (the rotor flange portion) may become a housing, an axial electromagnetic bearing, or the like due to axial expansion caused by thermal expansion of the rotor. There was a problem that the part and the rotor were damaged.

  The present invention has been made in order to solve the above-described problems, and the purpose of the present invention is that even if the rotation main shaft is thermally expanded due to a temperature rise caused by high-speed rotation or the like, the rotation main shaft is in another part. An object of the present invention is to provide a magnetic bearing device in which stable operation is ensured without being in contact with the fuel, and a fuel cell compressor in which stable operation is realized using the magnetic bearing device.

  In order to solve the above-described problems, the invention according to claim 1 estimates the surface temperature of the rotating main shaft in a magnetic bearing device including a pair of magnetic bearings that support the rotating main shaft in a non-contact state in the axial direction. And an electromagnet control for controlling the axial position of the rotating spindle by adjusting the excitation current applied to each electromagnet of the pair of magnetic bearings based on the surface temperature estimated by the temperature estimation unit And a means.

  According to this configuration, the axial position of the rotating main shaft is obtained by passing the excitation current adjusted by the electromagnet control means to the pair of magnetic bearings in the axial direction based on the surface temperature of the rotating main shaft estimated by the temperature estimating means. Can be controlled. Accordingly, it is possible to effectively avoid contact with other parts such as the housing and the magnetic bearing by the rotation main shaft extending in the axial direction due to thermal expansion. This also makes it possible to make the gap between the rotating main shaft and other parts such as the housing and the magnetic bearing as small as possible, thereby realizing a reduction in the size of a fuel cell compressor to which the magnetic bearing device is applied.

  The gist of a second aspect of the present invention is the magnetic bearing device according to the first aspect, wherein the temperature estimation means is a temperature sensor that measures the temperature of a stator coil that rotationally drives the rotary main shaft. .

  According to this configuration, a thermistor temperature sensor (overcurrent protection PTC thermistor) or the like disposed on the stator coil for protection of the electric motor unit can be used as a temperature estimation means for the surface temperature of the rotating spindle. It is no longer necessary to provide temperature estimation means for the magnetic bearing device, and the structure of the magnetic bearing device is simplified.

  According to a third aspect of the present invention, in the magnetic bearing device according to the first aspect, the temperature estimating means is a temperature compensation sensor used for temperature compensation of a position sensor that detects an axial position of the rotation main shaft. It is a summary.

  According to this configuration, for example, the output at normal temperature (20 ° C.) from the temperature compensation sensor can be used as a reference value, and the surface temperature of the rotating spindle can be estimated from the amount of change in the output with respect to the reference value as the temperature rises. Further, as described above, since the temperature compensation sensor used for temperature compensation of the position sensor is used as the temperature estimation means, it is not necessary to newly provide a temperature estimation means, and the structure of the magnetic bearing device is simplified.

  According to a fourth aspect of the present invention, there is provided a magnetic bearing device according to the third aspect, wherein each of the position sensor and the temperature compensation sensor comprises an overcurrent type ferrite core position sensor.

  According to this configuration, when the conductor close to the coil of the overcurrent type ferrite core position sensor is displaced, the eddy current flowing on the conductor surface changes and the impedance of the coil changes according to the ambient temperature. Thus, a temperature compensation sensor comprising an overcurrent type ferrite core position sensor can be used as the temperature estimation means.

  According to a fifth aspect of the present invention, in the magnetic bearing device according to any one of the first to fourth aspects, the electromagnet control means causes the rotation main shaft to move from the target floating position as the temperature of the rotation main shaft increases. The gist is to control an axial position of the rotating main shaft by adjusting an exciting current to be supplied to the pair of magnetic bearings based on a shift amount to be shifted.

  According to the configuration, the pair of magnetic bearings is energized by adjusting the control current according to the shift amount that the rotation main shaft shifts from the target levitation position to the steady current by the electromagnet control means with the temperature increase of the rotation main shaft. By adjusting the excitation current, thereby controlling the position of the rotating spindle in the axial direction, contact with other parts of the rotating spindle can be avoided.

  According to a sixth aspect of the present invention, in the magnetic bearing device according to the fifth aspect, the electromagnet control means causes the shift amount of the rotational main shaft to shift from the target flying position to zero as the temperature of the rotational main shaft increases. The gist is to control the position of the rotating main shaft in the axial direction.

  According to the configuration, the pair of magnetic bearings is energized by adjusting the control current according to the shift amount that the rotation main shaft shifts from the target levitation position to the steady current by the electromagnet control means with the temperature increase of the rotation main shaft. It is possible to adjust the excitation current, control the axial position of the rotation main shaft, and offset (move) the rotation main shaft in the axial direction by the axial expansion due to thermal expansion of the controlled rotation main shaft. As a result, the rotation main shaft extends in the axial direction due to thermal expansion, so that it is possible to reliably avoid contact with other parts such as a housing or a magnetic bearing that accommodates the rotation main shaft.

  According to a seventh aspect of the present invention, there is provided a fuel cell compressor including a rotating main shaft that supports an impeller for supplying compressed air to the fuel cell at a tip portion thereof, so as to support the rotating main shaft in a non-contact state. The gist is to use the magnetic bearing device according to claim 6.

  According to this configuration, in the fuel cell compressor, the excitation current adjusted by the electromagnet control means of the magnetic bearing device based on the surface temperature of the rotating spindle estimated by the temperature estimation means of the magnetic bearing device is used as a pair of axial directions. By energizing the magnetic bearing, the position of the rotary main shaft in the axial direction can be controlled. As a result, the rotation main shaft expands in the axial direction due to thermal expansion, so that the separation distance between the impeller pivotally supported on the rotation main shaft and the pressure volute is reduced as the temperature rises, and finally the impeller is moved to the pressure volute. It is possible to effectively avoid the problem of touching. In addition, as a result, in the fuel cell compressor, the gap between the other parts such as the impeller and the pressurized volute can be made as small as possible, so that downsizing is realized.

  According to an eighth aspect of the present invention, there is provided a turbo-type compressor having a rotating main shaft that supports an impeller for supplying compressed air to the outside at a tip portion thereof, so as to support the rotating main shaft in a non-contact state. The gist is to use the magnetic bearing device according to any one of Items 6.

  According to this configuration, in a general-purpose turbo compressor, the excitation current adjusted by the electromagnet control means of the magnetic bearing device is applied to the axial direction based on the surface temperature of the rotating spindle estimated by the temperature estimation means of the magnetic bearing device. By energizing the magnetic bearing, the position of the rotary spindle in the axial direction can be controlled. As a result, the rotation main shaft expands in the axial direction due to thermal expansion, so that the separation distance between the impeller pivotally supported on the rotation main shaft and the pressure volute is reduced as the temperature rises, and finally the impeller is moved to the pressure volute. It is possible to effectively avoid the problem of touching. In addition, as a result, in a general-purpose turbo compressor, the gap between other parts such as an impeller and a pressure volute can be made as small as possible, so that downsizing is realized.

  According to the present invention, even when the rotation main shaft is thermally expanded due to a temperature rise accompanying high-speed rotation or the like, a magnetic bearing device that ensures stable operation without the rotation main shaft contacting other parts, and Thus, it is possible to provide a fuel cell compressor that realizes stable operation using the magnetic bearing device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
<First Embodiment>
The magnetic bearing device of this embodiment is applied to a fuel cell compressor that is mounted on a vehicle such as an automobile and supplies mainly compressed air to a fuel cell as a power source of the vehicle.

  As shown in FIG. 1, the fuel cell compressor 1 includes an impeller 11 that supplies compressed air to the fuel cell, and an electric motor unit 10 that rotationally drives the impeller 11. The fuel cell compressor 1 is used in the vehicle in the horizontal state shown in FIG. 1 (in FIG. 1, the direction perpendicular to the axial direction of the rotor 12 is the vertical direction).

  The electric motor unit 10 includes a rotor 12 (rotary main shaft) that pivotally supports the impeller 11 at a tip end portion 12t, and a stator coil 13 that rotationally drives the rotor 12. A thermistor temperature sensor 20 for overcurrent protection is disposed on the coil winding portion 13 a of the stator coil 13. The impeller 11 and the electric motor unit 10 are accommodated in a bottomed cylindrical housing 15.

  The impeller 11 is rotatably accommodated in a pressure volute 16 constituting a part of the housing 15. Here, the pressurized volute 16 is provided with an air introduction path 16 a for introducing air into the fuel cell compressor 1 and an air discharge path 16 b for discharging compressed air to the outside of the fuel cell compressor 1. Then, due to the rotation of the impeller 11 by the rotational drive of the rotor 12, air is introduced and pressurized in the direction of the arrow a1 through the air introduction path 16a, and further in the compressed state through the air discharge path 16b as indicated by the arrow a2. It is discharged in the direction and supplied to the fuel cell of the vehicle via a humidifier (not shown).

  The rotor 12 has a central portion bulging radially outward to form a large-diameter portion 12c. The large-diameter portion 12c is sandwiched between the front end side (impeller 11 side) and the rear end side. Further, a pair of front and rear disk-shaped flange portions 12a and 12b made of a magnetic material such as iron are provided so as not to rotate relative to each other. The rotor 12 includes a pair of front and rear axial magnetic bearings 21 and 22 fixed to the housing 15 (the iron yoke portions of the axial magnetic bearings 21 and 22 include coil coils). The windings 21a and 22a are wound to constitute a plurality of electromagnets) and are supported in a non-contact state in the axial direction (axial direction) while facing the axial magnetic bearings 21, 22 is supported in a non-contact state in the radial direction (radial direction) by a pair of front and rear radial foil bearings 17a and 17b fixed at positions sandwiched between the two. In the electric motor section 10 shown in FIG. 1, the axial position sensor 23p that detects the position (displacement) of the rotor 12 in the axial direction and outputs a position detection signal is fixed to the sensor block 23. 15 at the center of the bottom 15a.

1 and 2, the magnetic bearing device 2 according to this embodiment includes the above-described axial magnetic bearings 21 and 22, the axial position sensor 23p as position detecting means, and the temperature estimating means for estimating the surface temperature of the rotor 12. Thermistor temperature sensor 20 as an electromagnet control means for controlling the electromagnets of the axial magnetic bearings 21 and 22 based on a position detection signal output from the machine body 201 described below and the axial position sensor 23p. The controller 202 is provided. Hereinafter, the axial direction of the rotor 12 is defined as the Z axis, and the two radial directions orthogonal to the Z axis are defined as the X axis and the Y axis. Also, numerical values (position or distance) along the Z axis are expressed as Z ₀ , Z, ΔZ, ΔL ₀ , ΔL, ΔL _max .

  Referring to FIG. 2, the machine main body 201 includes a pair of front and rear axial magnetic bearings 21 and 22 that support the rotor 12 in a non-contact state in the Z-axis direction, and two locations separated from each other in the Z-axis direction. Radial foil bearings 17a and 17b supported in a non-contact state in the axial direction and the Y-axis direction, an axial position sensor 23p that detects the position of the rotor 12 in the Z-axis direction and outputs a position detection signal, and estimates the surface temperature of the rotor 12 A thermistor temperature sensor 20 used as temperature estimation means for rotating the electric motor unit 10 that rotates the rotor 12 at high speed.

The controller 202 includes a position sensor circuit 23a electrically connected to the axial position sensor 23p, a temperature sensor circuit 20a electrically connected to the thermistor temperature sensor 20, a target floating position signal of the rotor 12, and the axial position sensor 23p. A DSP (DSP: Digital Signal Processor) board 24 serving as an electromagnet control signal output unit for outputting an electromagnet control signal based on the position detection signal, and an axial based on the electromagnet control signal output from the DSP board 24 A magnetic bearing drive circuit 25 as an electromagnet drive unit for driving the electromagnets of the magnetic bearings 21 and 22 and an inverter circuit 26 for controlling the electric motor unit 10 are provided. Here, a DSP 24a as a digital processing means capable of programming, a ROM 24b and a flash memory 24c as storage means, an A / D converter 24d, and a D / A converter 25e are connected to the DSP board 24 as shown in FIG. It is arranged in a state. Koko in, in the ROM24b, the information Nikansuru Mokuhyo Fujo Ichi _{Z 0} of Rota 12, Ori is Kakuno is programmed to be Shori in DSP24a, the Furasshu Memori 24c is Seigyo which was then Kioku the Seigyo Parameta of Akisharu Jiki Jikuuke 21,22 A parameter table and a bias current value table storing bias current values (steady current values) are provided.

  The position sensor circuit 23a drives the axial position sensor 23p, and based on the position detection signal proportional to the size of the gap between the lower end surface of the rotor 12 and the output of the axial position sensor 23p. The position in the axial direction is calculated, and a position detection signal Zas as the calculation result is output to the DSP 24a via the A / D converter 24d.

The temperature sensor circuit 20a drives the thermistor temperature sensor 20, and based on a temperature signal ts (surface temperature signal of the rotor 12) which is an output of the thermistor temperature sensor 20, the target of the rotor 12 stored in the ROM 24b. An offset amount ΔZ to be subtracted from the flying position Z ₀ is calculated, and a corrected flying position signal (Z ₀ −ΔZ) as a result of the calculation is output to the DSP 24a via the A / D converter 24d and stored in the flash memory 24c. .

The DSP 24a, in accordance with the program stored in the ROM 24b, in the Z-axis direction, the rotor 12 position detection signal Zas input from the A / D converter 24d and the corrected flying position signal (stored in the flash memory 24c) Z ₀ -ΔZ), an electromagnet control signal for each electromagnet of the axial magnetic bearings 21 and 22 is calculated by the PID operation, and this is output to the magnetic bearing drive circuit 25 via the D / A converter 25e. .

  The magnetic bearing drive circuit 25 supplies the rotor 12 with the excitation current obtained by matching the control current based on the electromagnet control signal from the DSP 24a with the steady current in the steady state to the electromagnets of the axial magnetic bearings 21 and 22. Feedback control is performed so as to support the corrected flying position in a non-contact state. That is, in the magnetic bearing device 2, the center of the rotor 12 coincides with the mechanical center position, the magnetic center position, and the sensor center position.

  On the other hand, the DSP 24a outputs a rotational speed command signal for the electric motor unit 10 to the inverter circuit 26, and the inverter circuit 26 controls the rotational speed of the electric motor unit 10 based on the rotational speed command signal. Thus, the rotor 12 is supported in a non-contact state at the target floating position or the corrected floating position by the axial magnetic bearings 21 and 22 and the radial foil bearings 17a and 17b, and is driven to rotate by the electric motor unit 10.

In the present embodiment, the offset amount ΔZ described above is calculated in the temperature sensor circuit 20a as follows. 3 (a) and 3 (b), the rotor 12 rotates at a high speed, and the air in the housing 15 is transmitted by heat generated by the stator coil 13 that rotationally drives the rotor 12. When the rotor 12 is heated, the amount of expansion on the impeller 11 side of the rotor 12 during steady operation in which the rotor 12 rotates at the target floating position Z ₀ , that is, the shift amount of the target floating position of the rotor 12 is ΔL ₀ , The surface temperature of the rotor 12 at that time is t ₀ (° C.), the maximum shift amount when the rotor 12 rotates at high speed is ΔL _max , and the surface temperature of the rotor 12 at that time is t _max (° C.).

Then, since the shift amount ΔL on the impeller 11 side of the rotor 12 when the surface temperature is t (° C.) is considered to be approximately proportional to the surface temperature difference (t−t ₀ ), it is given by the following expression 1.
ΔL = ΔL ₀ + (ΔL _max −ΔL ₀ ) · (t−t ₀ ) / (t _max −t ₀ ) (Expression 1)
Here, since the surface temperature t (° C.) of the rotor 12 is mainly derived from the heat generation of the stator coil 13, it can be considered to be proportional to the temperature signal ts from the thermistor temperature sensor 20 described above. Therefore, when the proportionality constant is k, it is given by the following equation 2.

t = k · ts (Expression 2)
From this equation 2 and the above equation 1, the following equation 3 is obtained.
ΔL = ΔL ₀ + · (ΔL _max −ΔL ₀ ) · (k · ts−t ₀ ) / (t _max −t ₀ ) (Equation 3)
The offset amount ΔZ, the surface temperature is a value obtained by subtracting the shift amount [Delta] L ₀ of the steady operation from the shift amount [Delta] L of the floating position of the rotor 12 when the t (℃) (ΔL-ΔL 0), i.e., the offset ΔZ may be caused to match the amount of shift the rotor 12 is shifted from the target levitated position Z ₀ with an increase in temperature of the rotor 12. In other words, if the offset amount ΔZ is adjusted such that (ΔL−ΔL ₀ ), which is a shift amount by which the rotor 12 shifts from the target flying position Z _{0 as} the temperature of the rotor 12 rises, eventually becomes zero. Therefore, the offset amount ΔZ is calculated from the above equation 3 according to the following equation 4.

ΔZ = ΔL−ΔL ₀ = (ΔL _max −ΔL ₀ ) · (k · ts−t ₀ ) / (t _max −t ₀ ) (Expression 4)
As described above, according to the magnetic bearing device 2 of the present embodiment, the following operations and effects can be obtained.

  (1) In the present embodiment, based on the surface temperature t (° C.) of the rotor 12 estimated by the thermistor temperature sensor 20 as the temperature estimation means, the controller 202 as the electromagnet control means installs the housing 15 in which the rotor 12 is accommodated. The exciting current that is supplied to the pair of front and rear axial magnetic bearings 21 and 22 disposed in the axial direction is adjusted. Thus, the position of the rotor 12 in the Z-axis direction is controlled, and the rotor 12 can be offset (moved) in the Z-axis direction by the amount of expansion on the impeller 11 side in the Z-axis direction due to thermal expansion of the rotor 12. This reliably prevents the rotor 12 from coming into contact with other parts such as the housing 15 and the radial foil bearings 17a and 17b.

  (2) In the present embodiment, normally, the thermistor temperature sensor 20 disposed in the stator coil 13 for protecting the electric motor unit 10 can be used as a temperature estimation means for the surface temperature of the rotor 12, and a new temperature estimation means is provided. The structure of the magnetic bearing device is simplified.

  (3) In the present embodiment, in the fuel cell compressor 1, based on the surface temperature t (° C.) of the rotor 12 estimated by the thermistor temperature sensor 20 that is the temperature estimation means of the magnetic bearing device 2, The controller 202, which is an electromagnet control means, adjusts the excitation current that is passed through the pair of front and rear axial magnetic bearings 21 and 22 disposed in the Z-axis direction of the housing 15. Thus, the position of the rotor 12 in the Z-axis direction is controlled, and the rotor 12 can be offset in the Z-axis direction by the amount of expansion on the impeller 11 side in the Z-axis direction due to thermal expansion of the rotor 12. As a result, the rotor 12 expands in the Z-axis direction due to thermal expansion, so that the separation distance between the impeller 11 pivotally supported by the rotor 12 and the pressure volute 16 is reduced as the temperature rises, and finally the impeller 11 Can be effectively avoided from contacting the pressure volute 16. This also allows the gap between the impeller 11 and the pressure volute 16 and other parts of the fuel cell compressor 1 to be as small as possible, increasing the degree of design freedom and reducing the size of the fuel cell compressor 1. Realized.

<Second Embodiment>
In this embodiment, instead of the overcurrent protection thermistor temperature sensor 20 used as the temperature estimation means in the first embodiment, an axial that detects the position of the rotor 12 (rotary spindle) in the Z-axis direction as the temperature estimation means. The configuration is the same as that of the first embodiment except that a temperature compensation sensor used for temperature compensation of the position sensor 23p is used. A description thereof will be omitted.

  The machine main body 201a of this embodiment is used for temperature compensation of the axial position sensor 23p, which detects the position of the rotor 12 in the Z-axis direction and outputs a position detection signal, with reference to FIG. A temperature compensation sensor 23b is provided.

  As shown in FIG. 5A, the axial position sensor 23p and the temperature compensation sensor 23b are fixed in a state of being close to each other in a disc-shaped sensor block 23 provided at the center position of the bottom portion 15a of the housing 15. Has been.

  Specifically, referring to FIG. 5A, the axial position sensor 23p and the temperature compensation sensor 23b are both composed of an overcurrent type ferrite core position sensor, and are wound around the ferrite core 23s and the ferrite core 23s. A rotated coil 23c is provided. The axial position sensor 23p shown in FIG. 5A is located on the central axis of the rotor 12, and is in a state in which the separation distance from the rotor 12 can be accurately detected. On the other hand, the temperature compensation sensor 23b is provided with a dummy target 23g so as to face the ferrite core 23s, and a constant distance between the ferrite core 23s and the dummy target 23g can always be detected. Yes. This separation distance is set to be equal to the separation distance between the axial position sensor 23p and the end surface (detected surface) of the rotor 12 at normal temperature (20 ° C.). The dummy target 23g is made of the same metal material as that of the rotor 12. In the temperature compensation sensor 23b, a spacer made of a resin and having a uniform thickness is provided between the dummy target 23g and the ferrite core 23s. 23d is interposed.

  The sensor block 23 includes a wiring portion that electrically connects the sensor block main body 23h made of a metal material, the axial position sensor 23p and the temperature compensation sensor 23b, and the position sensor circuit 23a and the temperature compensation sensor circuit 20b. It consists of a resin part to be fixed. The axial position sensor 23p and the temperature compensation sensor 23b are fixed to the sensor block body 23h.

  The axial position sensor 23p and the temperature compensation sensor 23b utilize the property that when the conductor close to the coil 23c is displaced, the eddy current flowing on the surface of the conductor is changed and the impedance of the coil 23c is changed. The position of the conductor is estimated from the relationship of outputs from the overcurrent type ferrite core position sensor as the position sensor 23p and the temperature compensation sensor 23b.

  Referring to FIG. 4, the controller 202a of the present embodiment includes a position sensor circuit 23a electrically connected to the axial position sensor 23p and a temperature compensation sensor circuit 20b electrically connected to the temperature compensation sensor 23b. I have. The DSP board 24e is provided with an A / D converter 25f connected to the temperature compensation sensor 23b and an A / D converter 25d connected to the position sensor circuit 23a.

  As in the first embodiment, the position sensor circuit 23a drives the axial position sensor 23p and generates a distance signal proportional to the size of the gap between the lower end surface of the rotor 12 and the output of the axial position sensor 23p. Based on this, the position of the rotor 12 in the Z-axis direction is calculated, and the position detection signal Zas as the calculation result is output to the DSP 24a via the A / D converter 25d.

  The temperature compensation sensor circuit 20b drives the temperature compensation sensor 23b, and based on the distance signal proportional to the separation distance from the dummy target 23g, which is the output of the temperature compensation sensor 23b, the Z of the dummy target 23g. The position in the axial direction is calculated, and a position detection signal Zcs that is the calculation result is output to the DSP 24a via the A / D converter 25f. Further, a part of the position detection signal Zcs is also output to the comparator 27 provided on the output side of the position sensor circuit 23a, and in the comparator 27, the position detection signal Zcs is output from the position sensor circuit 23a. A deviation is taken, and a signal based on the deviation (Zas-Zcs) is input to the DSP 24a and processed by a program stored in the ROM 24b.

  Hereinafter, the operations of the axial position sensor 23p and the temperature compensation sensor 23b will be described in more detail. When the rotor 12 is displaced with respect to the axial position sensor 23p, that is, when the separation distance Za between the axial position sensor 23p and the rotor 12 is changed, the separation distance is transferred from the axial position sensor 23p to the DSP 24a via the position sensor circuit 23a. A position detection signal Zas corresponding to Za is output.

As shown in FIG. 5B, the position detection signal Zas decreases in inverse proportion to the increase in the separation distance Za between the axial position sensor 23p and the rotor 12. In FIG. 5B, the position detection signal Zas = Zas _{(Za = Zac)} when the separation distance Za = Zac (Zac: a predetermined distance in the separation distance Za _{) is} assumed.

  Further, as shown in FIG. 5C, the position detection signal Zas, which is the output of the axial position sensor 23p via the position sensor circuit 23a when the separation distance Za = Zac, is the environmental temperature t ( ° C), that is, increases linearly with respect to the temperature of the sensor block 23. Similarly, the position detection signal Zcs, which is the output of the temperature compensation sensor 23b via the temperature compensation sensor circuit 20b, is the environment temperature t (° C.) of the temperature compensation sensor circuit 20b, that is, the environment of the axial position sensor 23p. It increases in a linear function with respect to the temperature of the sensor block 23 equal to the temperature t (° C.).

Here, when the difference (deviation) (Zas−Zcs) between the position detection signal Zas and the position detection signal Zcs is taken by the comparator 27 shown in FIG. 4, the difference is the environmental temperature t (° C.) in the position detection signal Zas. In other words, in the present embodiment, the position detection signal Zas is not the signal itself, and the temperature drift is canceled out by the position detection signal Zcs. Based on the difference (Zas−Zcs), the floating position of the rotor 12 is controlled. In FIG. 5C, the output (position detection signal) via the temperature compensation sensor circuit 20b of the temperature compensation sensor 23b when the ambient temperature (normal temperature) is 20 ° C. is Zcs _{(t = 20 ° C.)} . .

Then, referring to FIG. 5C, when the position detection signal from the temperature compensation sensor 23b at an arbitrary environmental temperature t ₁ (° C.) is Zcs _{(t = t 1 ° C.)} , the position detection is performed as described above. Since the signal Zcs increases in a linear function with respect to the environmental temperature t (° C.), the following equation 5 is established with a being a proportional constant of the linear portion.

Zcs _{(t = t1 ° C.)} −Zcs _{(t = 20 ° C.)} = A · (t ₁ −20) (Formula 5)
When the above equation 5 is transformed with respect to t ₁ , the following equation 6 is obtained.
t ₁ = (1 / a) · (Zcs _{(t = t 1 ° C.) −} Zcs _{(t = 20 ° C.)} ) + 20
= (1 / a) · Zcs _{(t = t1 ° C.)} + 20− (1 / a) · Zcs _{(t = 20 ° C.)} (Formula 6)
Here, 20− (1 / a) · Zcs _{(t = 20 ° C.)} ≈0, that is, Zcs _{(t = 20 ° C.)} ≈20a, the position detection signal input from the temperature compensation sensor 23b. If the gain (amplification factor) is adjusted by the temperature compensation sensor circuit 20b to obtain Zcs, the environmental temperature t ₁ (° C.) is expressed by the following equation (7).

t ₁ = (1 / a) · Zcs _{(t = t 1 ° C.)} (Expression 7)
That is, it can be considered that the position detection signal Zcs by the temperature compensation sensor 23b is proportional to the environmental temperature t (° C.) of the temperature compensation sensor 23b. Further, the surface temperature t (° C.) of the rotor 12 increases with the environmental temperature t (° C.) of the temperature compensation sensor 23b, that is, the temperature of the sensor block 23, and can be considered to be proportional to the temperature. Is k ′, the surface temperature t (° C.) of the rotor 12 is given by the following equation (8).

t = k ′ · Zcs (Expression 8)
When the offset amount ΔZ referred to in the first embodiment is obtained by using the equation 8 by the same method as in the first embodiment, the following equation 9 is obtained.

ΔZ = (ΔL _max −ΔL ₀ ) · (k ′ · Zcs−t ₀ ) / (t _max −t ₀ ) (Equation 9)
As described above, according to the magnetic bearing device 2 of the present embodiment, the following operations and effects can be obtained in addition to the operations and effects equivalent to the operations and effects obtained in the first embodiment.

(4) In this embodiment, the position detection signal Zcs _{(t = 20 ° C.)} , which is an output at normal temperature (20 ° C.) by the temperature compensation sensor 23b, is used as a reference value, and the reference value Zcs _{(t =} The surface temperature t (° C.) of the rotor 12 can be estimated from the amount of change (Zcs _{(t = t 1 ° C.) −} Zcs _{(t = 20 ° C.)} ) of the position detection signal Zcs, which is an output with respect to _{20 ° C.)} . Further, since the temperature compensation sensor 23b used for temperature compensation of the axial position sensor 23p is used as the temperature estimation means as described above, it is not necessary to newly provide a temperature estimation means, and the structure of the magnetic bearing device 2 is simplified. Is done.

  (5) In this embodiment, when the conductor close to the coil 23c of the overcurrent type ferrite core position sensor is displaced, the impedance of the coil 23c, which changes and changes the eddy current flowing on the conductor surface, further changes to the environmental temperature t (° C.). The temperature compensation sensor 23b composed of an overcurrent type ferrite core position sensor can be used as the temperature estimation means by utilizing the property that changes correspondingly.

The above embodiment may be modified as follows.
In each of the above embodiments, the radial foil bearings 17a and 17b are used as the radial bearing of the rotor 12. However, a radial magnetic bearing that supports the rotor 12 in a non-contact state in the radial direction may be used.

  In each of the above embodiments, the DSP 24a is used for the arithmetic processing. However, the present invention is not limited to this. For example, a personal computer, a CPU (Central Processing Unit), or the like may be used.

  In each of the above embodiments, the inner rotor type magnetic bearing device that rotates inside the housing 15 in which the rotor 12 is a fixed part has been described. However, the technical idea of the present invention is that the rotor 12 is a fixed part. The present invention can also be applied to an outer rotor type magnetic bearing device that rotates on the outside.

  In the first embodiment, the thermistor temperature sensor 20 that measures the temperature of the stator coil 13 that rotationally drives the rotor 12 is used as the temperature estimation means. However, as another example, the surface temperature of the rotor 12 (rotary spindle) A non-contact thermometer for measuring the temperature may be appropriately disposed. In the case of a compressor, it is also possible to estimate the surface temperature of the rotor 12 (providing temperature estimation means) from the result of measuring the exhaust temperature by arranging a thermocouple or the like in the compressed air discharge path.

  In each of the above embodiments, an example in which the magnetic bearing device is applied to a fuel cell compressor has been shown. However, the magnetic bearing device of the present invention is applied to a general-purpose turbo compressor for producing compressed air such as other turbo molecular pumps. Can be applied in the same manner.

  In the second embodiment, the temperature compensation sensor 23b is fixed to the sensor block 23 arranged at the center position of the bottom 15a of the housing 15, but the temperature drift of the position detection signal Zas can be canceled by the position detection signal Zcs. As long as the temperature rise is high, the housing 15 on the side of the impeller 11 and the axial magnetic bearings 21 and 22 can be disposed.

  In the second embodiment, the dummy target 23g of the temperature compensation sensor 23b is made of the same metal material as the rotor 12. However, as long as the temperature drift of the position detection signal Zas can be offset by the position detection signal Zcs, It is also possible to configure with other materials, for example, aluminum or electromagnetic steel sheets.

The axial sectional view of the compressor for fuel cells concerning the embodiment of the present invention. The block diagram of the magnetic bearing apparatus which concerns on 1st Embodiment applied to the compressor for fuel cells of FIG. (A) is a schematic diagram showing an extended state and a position control state of the rotor when the rotor is heated, and (b) is a graph showing a relationship between the surface temperature t of the rotor and the shift amount ΔL on the impeller side of the rotor. Figure. The block diagram of the magnetic bearing apparatus which concerns on 2nd Embodiment applied to the compressor for fuel cells of FIG. (A) is sectional drawing of the sensor block which concerns on 2nd Embodiment, (b) is a graph figure which shows the relationship between the separation distance Za of an axial position sensor and a rotor, and the position detection signal Zas, (c) is The graph which shows the relationship between the environmental temperature t of an axial position sensor, and the position detection signal Zs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell compressor, 2 ... Magnetic bearing apparatus, 11 ... Impeller, 12 ... Rotor (rotary main shaft), 13 ... Stator coil, 20 ... Thermistor temperature sensor (temperature estimation means), 21, 22 ... Axial magnetic bearing, 23 ... sensor block, 23b ... temperature compensation sensor, 23p ... axial position sensor, 201, 201a ... machine body, 202, 202a ... controller (electromagnet control means).

Claims (8)

In a magnetic bearing device comprising a pair of magnetic bearings that support the rotating spindle in a non-contact state in the axial direction,
Temperature estimating means for estimating the surface temperature of the rotating spindle;
Electromagnet control means for controlling the position in the axial direction of the rotating spindle by adjusting the excitation current applied to each electromagnet of the pair of magnetic bearings based on the surface temperature estimated by the temperature estimation means. A magnetic bearing device. The magnetic bearing device according to claim 1,
A magnetic bearing device, wherein the temperature estimation means is a temperature sensor that measures the temperature of a stator coil that rotationally drives the rotary main shaft. The magnetic bearing device according to claim 1,
A magnetic bearing device, wherein the temperature estimation means is a temperature compensation sensor used for temperature compensation of a position sensor that detects the axial position of the rotating spindle. The magnetic bearing device according to claim 3,
Each of the position sensor and the temperature compensation sensor is a magnetic bearing device including an overcurrent type ferrite core position sensor in which a coil is wound around a ferrite core. In the magnetic bearing device according to any one of claims 1 to 4,
The electromagnet control means adjusts an excitation current energized to the pair of magnetic bearings based on a shift amount by which the rotating main shaft shifts from a target flying position as the temperature of the rotating main shaft increases, and an axial direction of the rotating main shaft Magnetic bearing device that controls the position of the motor. The magnetic bearing device according to claim 5,
A magnetic bearing device in which the electromagnet control means controls the axial position of the rotation main shaft so that the amount of shift by which the rotation main shaft shifts from the target levitation position becomes zero as the temperature of the rotation main shaft increases. In a fuel cell compressor having a rotating main shaft that supports an impeller for supplying compressed air to a fuel cell at a tip portion,
7. A fuel cell compressor using the magnetic bearing device according to claim 1 to support the rotating main shaft in a non-contact state. In a turbo compressor having a rotating main shaft that supports an impeller that supplies compressed air to the outside at its tip,
A turbo compressor using the magnetic bearing device according to any one of claims 1 to 6, in order to support the rotating main shaft in a non-contact state.

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