JP2007162728A - Motor integrated magnetic bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor integrated magnetic bearing device stably controllable even when axial overload operates. <P>SOLUTION: The motor integrated magnetic bearing device comprises rolling bearings and magnetic bearing combined, the rolling bearings 15, 16 supporting radial load, the magnetic bearing supporting one or both of axial load and bearing pre-load. An electromagnet 17 as part of the magnetic bearing is mounted on a spindle housing 14 so as to be opposed in no contact to two thrust plates 13a, 13b provided on the spindle 13. A motor rotor 28a is formed in a space between the two thrust plates 13a, 13b. An electromagnet target is formed on the face of one of the thrust plates 13a, 13b, and a permanent magnet 28aa for the motor rotor 28a is arranged on the face of the other. A motor stator 28b is arranged to be clamped by the permanent magnet 28aa. A controller 19 controls the electromagnet 17 in response to the output of a sensor 18 which detects force in the axial direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic bearing device used in an air cycle refrigeration cooling turbine unit or the like, and in particular, a rolling bearing and a magnetic bearing are used together so that the magnetic bearing supports one or both of an axial load and a bearing preload. The present invention relates to a motor-integrated magnetic bearing device.

  Since the air cycle refrigeration cooling system uses air as a refrigerant, energy efficiency is insufficient as compared with the case of using chlorofluorocarbon or ammonia gas, but it is preferable in terms of environmental protection. In addition, in facilities where refrigerant air can be directly blown into, such as a refrigerated warehouse, the total cost may be reduced by omitting the internal fan and defrost, etc. In such applications, the air cycle refrigeration cooling system Has been proposed (for example, Patent Document 1).

Further, it is known that the theoretical efficiency of air cooling is equal to or higher than that of Freon or ammonia gas in a deep coal region of -30 ° C to -60 ° C. However, it is also stated that obtaining the theoretical efficiency of the air cooling is not possible until there is an optimally designed peripheral device. The peripheral device is a compressor, an expansion turbine, or the like.
As the compressor and the expansion turbine, a turbine unit in which a compressor impeller and an expansion turbine impeller are attached to a common main shaft is used (Patent Document 1).

In addition, as a turbine compressor which processes process gas, a turbine impeller is attached to one end of the main shaft, a compressor impeller is attached to the other end, and the main shaft is supported by a journal and a thrust bearing that is controlled by an electromagnet current. A compressor has been proposed (Patent Document 2).
In addition, although it is a proposal for a gas turbine engine, in order to avoid the thrust load acting on the rolling bearing for supporting the main shaft from shortening the bearing life, the thrust load acting on the rolling bearing should be reduced by the thrust magnetic bearing. Has been proposed (Patent Document 3).
Japanese Patent No. 2623202 Japanese Patent Application Laid-Open No. 7-91760 JP-A-8-261237

As described above, as the air cycle refrigeration cooling system, in order to obtain the theoretical efficiency of air cooling that is highly efficient in the deep coal region, an optimally designed compressor and expansion turbine are required.
As the compressor and the expansion turbine, a turbine unit in which the compressor wheel and the expansion turbine wheel are attached to a common main shaft as described above is used. In this turbine unit, the compressor impeller can be driven by the power generated by the expansion turbine, thereby improving the efficiency of the air cycle refrigerator.

However, in order to obtain practical efficiency, it is necessary to keep the gap between each impeller and the housing minute. The fluctuation of the gap hinders stable high-speed rotation and causes a decrease in efficiency.
In addition, a thrust force acts on the main shaft by the air acting on the compressor impeller and the turbine impeller, and a thrust load is applied to the bearing that supports the main shaft. The rotation speed of the main shaft of the turbine unit in the air cycle refrigeration cooling system is 80,000 to 100,000 rotations per minute, which is very high compared with a bearing for general use. For this reason, the thrust load as described above causes a decrease in long-term durability and life of the bearing supporting the main shaft, and decreases the reliability of the turbine unit for air cycle refrigeration cooling. Unless such a problem of long-term durability of the bearing is solved, it is difficult to put the air cycle refrigeration cooling turbine unit into practical use. However, the technique disclosed in Patent Document 1 has not yet been solved for the deterioration of the long-term durability of the bearing against the load of the thrust load under the high-speed rotation.

  In the case where the main shaft is supported by a journal bearing made of a magnetic bearing and a thrust bearing, such as the magnetic bearing type turbine compressor of Patent Document 2, the journal bearing does not have a restriction function in the axial direction. Therefore, if there is an unstable factor in controlling the thrust bearing, it is difficult to perform stable high-speed rotation while maintaining a minute gap between the impeller and the diffuser. In the case of a magnetic bearing, there is also a problem of contact when the power is stopped.

  Accordingly, the inventors of the present invention have developed a motor-integrated magnetic bearing device as shown in FIG. 5 in order to solve the above problems. This motor-integrated magnetic bearing device rolls the radial load of the main shaft 53 in an air cycle refrigeration cooling turbine unit in which the compressor impeller 46a of the compressor 46 and the turbine impeller 47a of the expansion turbine 47 are attached to both ends of the main shaft 53. The axial loads are supported by the electromagnets 57 by the bearings 55 and 56, respectively, and the compressor impeller 46a is rotationally driven by the driving force of the motor 68 provided coaxially with the main shaft 53 and the driving force of the turbine impeller 47a. Is.

  The electromagnet 57 that supports the axial load is provided on each side of two thrust plates 53a and 53b made of a ferromagnetic material that are arranged vertically and coaxially with the main shaft 53 in the axial direction (one side facing the expansion turbine 47 in the thrust plate 53a, In the thrust plate 53b, a pair of left and right members are disposed so as to face each other in a non-contact manner toward the compressor 46, and are controlled by the magnetic bearing controller 59 in accordance with the output of the sensor 58 that detects the axial force. . The motor 68 is of an axial gap type, and includes a motor rotor 68a and a motor stator 68b, and is disposed in a space sandwiched between the two thrust plates 53b. A pair of left and right motor rotors 68a is configured by arranging permanent magnets 68aa arranged at equal pitches in the circumferential direction on each side of the thrust plates 53a and 53b opposite to the side on which the electromagnets 57 are opposed. The Thus, between the permanent magnets 68aa arranged opposite to each other in the axial direction, the magnetic poles are set to be different from each other. The motor stator 68b is configured by arranging a coil 68ba so as to face each surface of the motor rotors 68a in a non-contact manner at a position between the pair of left and right motor rotors 68a. The motor 68 is controlled by a motor controller 69 independently of the electromagnet 57.

  According to the motor-integrated magnetic bearing device configured as described above, since the thrust force applied to the main shaft 53 is supported by the electromagnet 57, the thrust force acting on the rolling bearings 55 and 56 is reduced while suppressing an increase in torque without contact. be able to. As a result, the minute gaps between the respective impellers 46a and 47a and the housings 46b and 47b can be kept constant, and the long-term durability of the rolling bearing against the load of the thrust load can be improved.

  However, in the motor-integrated magnetic bearing device having the above-described configuration, the permanent magnet 68aa of the motor rotor 68a is fixed to each side of the thrust plates 53a and 53b by an adhesive. When the main shaft 53 is rotated at a high speed for a long period of time, the permanent magnet 68aa may be scattered from the thrust plates 53a and 53b by centrifugal force.

  The purpose of the present invention is to enable stable control even when the motor operates in a high load state and an excessive axial load is applied, to simplify the configuration of the controller, to shorten the length of the spindle, and to achieve high speed. It is an object of the present invention to provide a motor-integrated magnetic bearing device that can be rotated and can reliably prevent scattering due to a decrease in the adhesive force of a permanent magnet for a motor rotor.

  A motor-integrated magnetic bearing device according to the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, the magnetic bearing supports one or both of an axial load and a bearing preload, and The electromagnets constituting the magnet are mounted on the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner. Two thrust plates are provided apart in the axial direction. The motor rotor is formed in a space sandwiched between the two thrust plates, an electromagnet target is formed on one surface of the thrust plate, and a permanent magnet for the motor rotor is disposed on the other surface, and the permanent magnet Are arranged at an equal pitch in the circumferential direction so that the different poles face each other, and the motor stator is arranged so as to be sandwiched between the permanent magnets. And a controller that controls an electromagnet according to the output of a sensor that detects the axial force acting on the rolling bearing, and is formed by a rolling bearing and a supporting system for the rolling bearing. The synthetic spring has a relationship that the rigidity value is larger than the negative rigidity value of the motor portion, and a flange is formed on the outer diameter portion of the thrust plate. The motor unit includes, for example, a motor and the electromagnet.

According to this configuration, the rolling bearing and the magnetic bearing are used together, the rolling bearing supports the radial load, and the magnetic bearing supports one or both of the axial load and the bearing preload. Good support can be achieved, long-term durability of the rolling bearing can be ensured, and damage when the power supply is stopped in the case of supporting only the magnetic bearing can be avoided.
In addition, two electromagnets are arranged on the outer side in the axial direction of the two thrust plates provided on the main shaft side by side in the axial direction to form a magnetic bearing unit, and an axial gap type motor is arranged at a position sandwiched between the two thrust plates. Since the motor unit is used, the magnetic bearing unit and the motor unit can be made into a compact integrated structure. Therefore, the shaft length of the main shaft can be shortened, the natural frequency of the main shaft can be increased accordingly, and the main shaft can be rotated at high speed.
In particular, since the flange is formed on the outer diameter portion of the thrust plate, even if the adhesive force of the adhesive that fixes the permanent magnet for the motor rotor to the thrust plate is reduced due to thermal deterioration and aging, the spindle rotates. It is possible to prevent the permanent magnets from being scattered from the thrust plate by the accompanying centrifugal force with the scissors at the outer diameter portion of the thrust plate.
Further, the stiffness value of the synthetic spring formed by the rolling bearing and the rolling bearing support system is greater than the negative stiffness value of the synthetic spring formed by the motor unit (including the electromagnet). Therefore, even when the motor operates at a high load and an excessive axial load is applied, the phase of the mechanical system can be prevented from being delayed by 180 ° in the control band, and the controlled object can be made stable. The configuration can be simplified.

  In this invention, the height of the ridge formed on the thrust plate may be equal to or higher than the thickness of the permanent magnet. If the height of the thrust plate ridge is lower than the thickness of the permanent magnet, when the permanent magnet is pressed against the heel, the edge load generated at the edge of the heel acts on the side of the permanent magnet and the permanent magnet is compressed and broken. There is a possibility, but if the height of the ridge of the thrust plate is equal to or higher than the thickness of the permanent magnet, it is possible to prevent the edge load generated at the edge of the ridge from acting on the side of the permanent magnet, Compressive fracture of the permanent magnet can be avoided.

  In this invention, on the main shaft, the compressor side impeller and the turbine side impeller are fitted to the common main shaft of the thrust plate and the motor rotor, and either or both of the motor power and the power generated by the turbine side impeller, It may be applied to a compressor length turbine system for driving a compressor side impeller. In the case of this configuration, a stable high-speed rotation of the main shaft can be obtained while maintaining an appropriate gap between the impellers, and the long-term durability and life of the bearing can be improved.

In the present invention, the compression / expansion turbine system to which the motor-integrated magnetic bearing device is applied includes compression by precompression means, cooling by a heat exchanger, compression by a compressor of a turbine unit, and other heat exchange with respect to inflow air. It may be applied to an air cycle refrigeration cooling system that sequentially performs cooling by a vessel and adiabatic expansion by the expansion turbine of the turbine unit.
When the compression / expansion turbine system to which the motor-integrated magnetic bearing device is applied is applied to such an air cycle refrigeration / cooling system, the main shaft is stable in the compression / expansion turbine system while maintaining an appropriate clearance of each impeller. Since high-speed rotation can be obtained and the long-term durability and life of the bearing can be improved, the reliability of the entire compression / expansion turbine system, and the air cycle refrigeration cooling system as a whole, is improved. In addition, stable high-speed rotation, long-term durability, and reliability of the main shaft bearing of the compression / expansion turbine system, which is the bottleneck of the air cycle refrigeration cooling system, improve the practical use of the air cycle refrigeration cooling system. .

  A motor-integrated magnetic bearing device according to the present invention uses a rolling bearing and a magnetic bearing in combination, the rolling bearing supports a radial load, the magnetic bearing supports one or both of an axial load and a bearing preload, and The electromagnet constituting the bearing is mounted on the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft in a non-contact manner. Two thrust plates are provided apart in the axial direction. The motor rotor is formed in a space sandwiched between the two thrust plates, an electromagnet target is formed on one surface of the thrust plate, and a permanent magnet for the motor rotor is disposed on the other surface, and the permanent magnet Are arranged at an equal pitch in the circumferential direction so that the different poles face each other, and the motor stator is arranged so as to be sandwiched between the permanent magnets. And a controller that controls an electromagnet according to the output of a sensor that detects the axial force acting on the rolling bearing, and is formed by a rolling bearing and a supporting system for the rolling bearing. Since the stiffness value of the synthetic spring is larger than the negative stiffness value of the synthetic spring formed by the electromagnet and the motor portion, and the flange is formed on the outer diameter portion of the thrust plate, the permanent magnet for the motor rotor is Even if the adhesive strength of the adhesive fixed to the thrust plate decreases due to thermal deterioration and secular change, it prevents the permanent magnet from scattering from the thrust plate due to the centrifugal force associated with the rotation of the spindle by stroking the outer diameter portion of the thrust plate can do. Furthermore, even when the motor operates in a high load state and an excessive axial load is applied, stable control is possible, the configuration of the controller can be simplified, and the spindle can be rotated at high speed.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of a turbine unit 5 incorporating the motor-integrated magnetic bearing device of this embodiment. The turbine unit 5 constitutes a compression / expansion turbine system, and includes a compressor 6 and an expansion turbine 7. The compressor impeller 6 a of the compressor 6 and the turbine impeller 7 a of the expansion turbine 7 are fitted to both ends of the main shaft 13. Match. The material of the main shaft 13 is low carbon steel with good magnetic properties.

In FIG. 1, the compressor 6 has a compressor housing 6b facing the compressor impeller 6a with a small gap d1, and compresses air sucked in the axial direction from the suction port 6c in the center by the compressor impeller 6a. And it discharges as shown by the arrow 6d from the exit (not shown) of an outer peripheral part.
The expansion turbine 7 has a turbine housing 7b that is opposed to the turbine impeller 7a via a minute gap d2, and the air sucked from the outer peripheral portion as indicated by an arrow 7c is adiabatically expanded by the turbine impeller 7a, It discharges in the axial direction from the discharge port 7d of the part.

  The motor-integrated magnetic bearing device in the turbine unit 5 supports a radial load applied to the main shaft 13 by a plurality of bearings 15 and 16, and either or both of the axial load and the bearing preload applied to the main shaft 13 are magnetized. An axial gap motor 28 that is supported by the electromagnet 17 that is a bearing and that rotationally drives the main shaft 13 is provided. The turbine unit 5 includes a sensor 18 that detects a thrust force acting on the main shaft 13, a magnetic bearing controller 19 that controls the main shaft supporting force of the electromagnet 17 according to the output of the sensor 18, Has a motor controller 29 for controlling the motor 28 independently.

  The electromagnet 17 is in non-contact with each surface of the two flange-shaped thrust plates 13a and 13b made of a ferromagnetic material that is provided perpendicularly and coaxially to the main shaft 13 so as to be aligned in the axial direction at the axial intermediate portion of the main shaft 13. A pair is installed in the spindle housing 14 so as to face each other. Specifically, one of the electromagnets 17 constituting the magnetic bearing unit is opposed to this one surface in a non-contact manner with the one surface facing the expansion turbine 7 of the thrust plate 13a located near the expansion turbine 7 as an electromagnet target. Installed in the spindle housing 14. Further, the other electromagnet 17 constituting the magnetic bearing unit has one surface facing the compressor 6 side of the thrust plate 13b located near the compressor 6 as an electromagnet target, and faces the spindle housing 14 so as to face this one surface in a non-contact manner. Installed.

The motor 28 is a motor unit including a motor rotor 28 a provided on the main shaft 13 along with the electromagnet 17, and a motor stator 28 b facing the motor rotor 28 a in the axial direction. Specifically, the motor rotor 28a that constitutes one part of the motor unit is arranged at a constant pitch in the circumferential direction on each side of the main shaft 13 opposite to the side where the electromagnets 17 of the thrust plates 13a and 13b face each other. By arranging the permanent magnets 28aa arranged side by side, a pair of left and right is configured. The permanent magnet 28aa is bonded and fixed to each side of the thrust plates 13a and 13b with an adhesive. Thus, between the permanent magnets 28aa arranged opposite to each other in the axial direction, the magnetic poles are set to be different from each other. In addition, flanges 13aa and 13ba having a height equal to or higher than the thickness of the permanent magnet 28aa are formed on the outer diameter portion of each side of the thrust plates 13a and 13b to which the permanent magnet 28aa is bonded and fixed. That is, the permanent magnet 28aa is bonded and fixed in an embedded state on each side of the thrust plates 13a and 13b so that the surface of the permanent magnet 28aa does not protrude from the tips of the flanges 13aa and 13ba. Since the main shaft 13 is made of low carbon steel having good magnetic properties, the thrust plates 13a and 13b provided so as to be integrated with the main shaft 13 are also used as the back yoke and the electromagnet target of the permanent magnet 28aa. it can.
The motor stator 28b, which is another part of the motor unit, is disposed without a core so as to face each surface of both the motor rotors 28a in a non-contact manner at a central position in the axial direction between the pair of left and right motor rotors 28a. The coil 28ba is installed in the spindle housing 14 and configured. The motor 28 rotates the main shaft 13 by Lorentz force acting between the motor rotor 28a and the motor stator 28b. Thus, since this axial gap type motor 28 is a coreless motor, the negative rigidity due to the magnetic coupling between the motor rotor 28a and the motor stator 28b is zero.

  The bearings 15 and 16 that support the main shaft 13 are rolling bearings and have a function of restricting the position in the axial direction. For example, a deep groove ball bearing or an angular ball bearing is used. In the case of a deep groove ball bearing, it has a thrust support function in both directions, and has the effect of returning the axial position of the inner and outer rings to the neutral position. These two bearings 15 and 16 are arranged in the vicinity of the compressor impeller 6a and the turbine impeller 7a in the spindle housing 14, respectively.

The main shaft 13 is a stepped shaft having a large-diameter portion 13c at an intermediate portion and small-diameter portions 13d at both ends. The bearings 15 and 16 on both sides have their inner rings 15a and 16a fitted into the small diameter portion 13d in a press-fit state, and one of the width surfaces engages with a stepped surface between the large diameter portion 13c and the small diameter portion 13d.
The portions of the spindle housing 14 closer to the impellers 6a and 7a than the bearings 15 and 16 on both sides are formed with an inner diameter surface close to the main shaft 13, and non-contact seals 21 and 22 are formed on the inner diameter surface. Yes. In this embodiment, the non-contact seals 21 and 22 are labyrinth seals in which a plurality of circumferential grooves are formed in the axial direction on the inner diameter surface of the spider housing 14, but other non-contact seal means may be used.

  The sensor 18 is provided on the stationary side in the vicinity of the bearing 16 on the turbine impeller 7a side, that is, on the spindle housing 14 side. The outer ring 16 b of the bearing 16 provided with the sensor 18 in the vicinity thereof is fitted in the bearing housing 23 in a fixed state. The bearing housing 23 has an inner flange 23a that is formed in a ring shape and engages with the width surface of the outer ring 16b of the bearing 16 at one end, and is movable in the axial direction on an inner diameter surface 24 provided on the spindle housing 14. It is mated. The inner collar 23a is provided at the center side end in the axial direction.

  The sensors 18 are distributed and arranged at a plurality of circumferential locations (for example, two locations) around the main shaft 13, a width surface on the inner flange 23 a side of the bearing housing 23, and one electromagnet 17 that is a member fixed to the spindle housing 14. It is interposed between. The sensor 18 is applied with preload by a sensor preload spring 25. The sensor preload spring 25 is housed in a housing recess provided in the spindle housing 14 and biases the outer ring 16 b of the bearing 16 in the axial direction, and preloads the sensor 18 via the outer ring 16 b and the bearing housing 23. . The sensor preload spring 25 is composed of, for example, coil springs provided at a plurality of locations in the circumferential direction around the main shaft 13.

  The preload by the sensor preload spring 25 is for the sensor 18 that detects the thrust force by the pressing force to detect any movement of the main shaft 13 in the axial direction. The magnitude is greater than the average thrust force acting on the main shaft 13 in the operating state.

  The bearing 15 on the non-arrangement side of the sensor 18 is installed so as to be movable in the axial direction with respect to the spindle housing 14 and is elastically supported by a bearing preload spring 26. In this example, the outer ring 15 b of the bearing 15 is fitted to the inner diameter surface of the spindle housing 14 so as to be movable in the axial direction, and the bearing preload spring 26 is interposed between the outer ring 15 b and the spindle housing 14. The bearing preload spring 26 biases the outer ring 15 b so as to face the step surface of the main shaft 13 with which the width surface of the inner ring 15 a is engaged, and applies a preload to the bearing 15. The bearing preload spring 26 includes coil springs and the like provided at a plurality of locations in the circumferential direction around the main shaft 13, and is accommodated in receiving recesses provided in the spindle housing 14. The bearing preload spring 26 has a smaller spring constant than the sensor preload spring 25.

The dynamic model of the motor-integrated magnetic bearing device in the turbine unit 5 can be constituted by a simple spring system. That is, the spring system includes a composite spring formed by the bearings 15 and 16 and a support system for these bearings (sensor preload spring 25, bearing preload spring 26, bearing housing 23, etc.), and a motor unit (motor 28 and electromagnet 17). ) Formed in parallel. In this spring system, the combined spring formed by the bearings 15 and 16 and the support system of these bearings has rigidity that acts in proportion to the amount of displacement in the direction opposite to the displaced direction, whereas in the motor portion. The formed composite spring has a negative stiffness that acts in proportion to the amount of displacement in the displaced direction.
For this reason, the magnitude relationship between the stiffnesses of the two composite springs described above is
Rigidity value of the composite spring by the bearing etc. <Negative rigidity value of the composite spring by the motor unit (1)
In this case, the phase of the mechanical system is delayed by 180 ° and becomes an unstable system. Therefore, in the magnetic bearing controller 19 for controlling the electromagnet 17, it is necessary to load a phase compensation circuit in advance. It becomes complicated.

Therefore, in the motor-integrated magnetic bearing device of this embodiment, the magnitude relationship between the rigidity of the two combined springs is as follows.
Rigidity value of the composite spring by the bearing etc.> Negative rigidity value of the synthetic spring by the motor unit (2)
It is said. In particular, in this motor-integrated magnetic bearing device, since the axial gap type motor 28 is a coreless motor as described above, the negative rigidity value acting on the motor 28 can be made zero, and the motor 28 is high. Even in the state where the load operation is performed and an excessive axial load is applied, the magnitude relationship of the above equation (2) can be maintained.
As a result, since the phase of the mechanical system can be prevented from being delayed by 180 ° in the control band, the controlled object can be stabilized even when the motor 28 is operated at a high load and an excessive axial load is applied. The circuit configuration of the controller 19 can be configured as a simple one using proportional or proportional integration as shown in FIG.
As a result, since the phase of the mechanical system can be prevented from being delayed by 180 ° in the control band, the controlled object of the magnetic bearing controller 19 can be stabilized even when the motor 28 is operated at a high load and an excessive axial load is applied. The circuit configuration of the controller 19 can be configured as a simple one using proportional or proportional integration as shown in FIG.

In the magnetic bearing controller 19 of FIG. 2 shown in the block diagram, the detection outputs P1 and P2 of each sensor 18 are added and subtracted by the sensor output calculation circuit 30, and the calculation result is compared with the reference value of the reference value setting means 32 by the comparator 31. By controlling the electromagnet 17 by performing a proportional integration (or proportional) process in which the calculated deviation is appropriately set according to the turbine unit 5 by the PI compensation circuit (or P compensation circuit) 33. The signal is calculated. The output of the PI compensation circuit (or P compensation circuit) 33 is input to power circuits 36 and 37 that drive the electromagnets 17 ₁ and 17 ₂ in each direction via diodes 34 and 35. The electromagnets 17 ₁ and 17 ₂ are a pair of electromagnets 17 facing the thrust plate 13a shown in FIG. 1, and only the attractive force acts. Therefore, the direction of current is determined in advance by the diodes 34 and 35, and the two electromagnets 17 are used. ₁ and 17 ₂ are selectively driven.

  In the motor controller 29 of FIG. 3 also shown in the block diagram, the phase adjustment circuit 38 adjusts the phase of the motor drive current using the rotation angle of the motor rotor 28a as a feedback signal based on the rotation synchronization command signal. Constant rotation control is performed by supplying a corresponding motor drive current from the motor drive circuit 39 to the motor stator 28b. The rotation synchronization command signal is calculated according to the output of a rotation angle detection sensor (not shown) provided in the motor rotor 28a.

The turbine unit 5 having this configuration is applied to, for example, an air cycle refrigeration cooling system, and is compressed by a compressor 6 so that air as a cooling medium can be efficiently heat-exchanged by a heat exchanger (not shown here) at a subsequent stage. Then, the temperature is increased, and the air cooled by the heat exchanger in the subsequent stage is cooled and discharged by adiabatic expansion to a target temperature, for example, a very low temperature of about −30 ° C. to −60 ° C. by the expansion turbine 7. Used for.
In such a use example, the turbine unit 5 includes a compressor impeller 6a and a turbine impeller 7a fitted on the main shaft 13 common to the thrust plate 13a and the motor rotor 28a, and the power of the motor 28 and the turbine impeller 7a. The compressor impeller 6a is driven by either one or both of the power generated in the above. For this reason, stable high-speed rotation of the main shaft 13 can be obtained while maintaining appropriate gaps d1 and d2 between the impellers 6a and 7a, and the long-term durability and life of the bearings 15 and 16 can be improved.

  That is, in order to ensure the efficiency of compression and expansion of the turbine unit 5, it is necessary to keep the gaps d1 and d2 between the impellers 6a and 7a and the housings 6b and 7b minute. For example, when this turbine unit 5 is applied to an air cycle refrigeration cooling system, ensuring this efficiency is important. On the other hand, since the main shaft 13 is supported by the rolling bearings 15 and 16, the axial position of the main shaft 13 is regulated to some extent by the restriction function of the axial position of the rolling bearing, and the impellers 6a and 7a The minute gaps d1 and d2 between the housings 6b and 7b can be kept constant.

However, a thrust force is applied to the main shaft 13 of the turbine unit 5 by the air pressure acting on the impellers 6a and 7a. Further, the turbine unit 5 used in the air cooling system rotates at a very high speed of about 80,000 to 100,000 rotations per minute, for example. Therefore, when the thrust force acts on the rolling bearings 15 and 16 that rotatably support the main shaft 13, the long-term durability of the bearings 15 and 16 decreases.
In this embodiment, since the thrust force is supported by the electromagnet 17, the thrust force acting on the rolling bearings 15 and 16 for supporting the main shaft 13 can be reduced while suppressing an increase in torque without contact. In this case, since the sensor 18 for detecting the thrust force acting on the main shaft 13 and the magnetic bearing controller 19 for controlling the supporting force by the electromagnet 17 according to the output of the sensor 18 are provided, the rolling bearings 15 and 16 are provided. Depending on the bearing specifications, it can be used in an optimum state against the thrust force.
In addition, two electromagnets 17 are arranged outside the two thrust plates 13a and 13b provided on the main shaft 13 to constitute a magnetic bearing unit, and an axial gap is positioned between the thrust plates 13a and 13b. Since the magnetic bearing unit and the motor unit are made into a compact integrated structure by arranging the motor 28 of the type, the shaft length of the main shaft 53 can be shortened, and the natural frequency of the main shaft 13 is increased accordingly. Thus, the main shaft 13 can be rotated at high speed.
Particularly, in this motor-integrated magnetic bearing device, since the flanges 13aa and 13ba are formed on the outer diameter portions of the thrust plates 13a and 13b, the permanent magnet 28aa for the motor rotor 28a is fixed to the thrust plates 13a and 13b. Even if the adhesive strength of the adhesive is reduced due to thermal deterioration and aging, the thrust magnet 13aa is scattered from the thrust plates 13a and 13b due to the centrifugal force accompanying the rotation of the main shaft 13, and the flange 13aa of the thrust plate outer diameter portion , 13ba.
If the height of the flanges 13aa and 13ba of the thrust plates 13a and 13b is lower than the thickness of the permanent magnet 28aa, when the permanent magnet 28aa is pressed against the flanges 13aa and 13ba, the flanges 13aa and 13ba are placed on the side surfaces of the permanent magnet 28aa. However, in this embodiment, the height of the flanges 13aa and 13ba is equal to or greater than the thickness of the permanent magnet 28aa. Since the height is set, it is possible to prevent the edge load generated at the edge portions of the flanges 13aa and 13ba from acting on the side surface of the permanent magnet 28aa and to avoid the compressive fracture of the permanent magnet 28aa.

  FIG. 4 shows the overall configuration of an air cycle refrigeration cooling system using the turbine unit 5. This air cycle refrigeration cooling system is a system that directly cools air in a space to be cooled 10 such as a refrigeration warehouse as a refrigerant. It has path 1. In this air circulation path 1, pre-compression means 2, first heat exchanger 3, compressor 6 of air cycle refrigeration cooling turbine unit 5, second heat exchanger 3, intermediate heat exchanger 9, and the turbine unit Five expansion turbines 7 are provided in order. The intermediate heat exchanger 9 exchanges heat between the inflow air near the intake port 1a in the same air circulation path 1 and the air that has been heated by the subsequent compression and cooled. The air in the vicinity of 1a passes through the heat exchanger 9a.

  The pre-compression means 2 comprises a blower or the like and is driven by a motor 2a. The first heat exchanger 3 and the second heat exchanger 8 have heat exchangers 3a and 8a for circulating a cooling medium, respectively, and a cooling medium such as water and an air circulation path in the heat exchangers 3a and 8a. Heat exchange with 1 air. Each of the heat exchangers 3 a and 8 a is connected to the cooling tower 11 by piping, and the cooling medium whose temperature is increased by heat exchange is cooled by the cooling tower 11. Note that an air cycle refrigeration cooling system that does not include the pre-compression means 2 may be used.

  This air cycle refrigeration cooling system is a system that keeps the space to be cooled 10 at about 0 ° C. to −60 ° C., and is 1 atmosphere at about 0 ° C. to −60 ° C. from the space to be cooled 10 to the inlet 1a of the air circulation path 1. Inflow of air. Note that the numerical values of temperature and atmospheric pressure shown below are examples that serve as a guide. The air that has flowed into the intake port 1a is used by the intermediate heat exchanger 9 to cool the downstream air in the air circulation path 1 and is heated to 30 ° C. The heated air remains at 1 atm, but is compressed to 1.4 atm by the pre-compression means 2, and the temperature is raised to 70 ° C. by the compression. Since the 1st heat exchanger 3 should just cool the air of 70 degreeC which raised temperature, even if it is cold water about normal temperature, it can cool efficiently and it cools to 40 degreeC.

The air at 40 ° C. and 1.4 atm cooled by heat exchange is compressed to 1.8 atm by the compressor 6 of the turbine unit 5, and the second heat is increased to about 70 ° C. by this compression. It is cooled to 40 ° C. by the exchanger 8. The 40 ° C. air is cooled to −20 ° C. by the −30 ° C. air in the intermediate heat exchanger 9. The atmospheric pressure is maintained at 1.8 atmospheric pressure discharged from the compressor 6.
The air cooled to −20 ° C. by the intermediate heat exchanger 9 is adiabatically expanded by the expansion turbine 7 of the turbine unit 5, cooled to −55 ° C., and discharged from the outlet 1 b to the cooled space 10. This air cycle refrigeration cooling system performs such a refrigeration cycle.

  In this air cycle refrigeration cooling system, in the turbine unit 5, stable high-speed rotation of the main shaft 13 can be obtained while maintaining appropriate gaps d1 and d2 between the impellers 6a and 7a, and the long-term durability of the bearings 15 and 16 can be improved. Since the long-term durability of the bearings 15 and 16 is improved by obtaining the improvement and the improvement of the life, the reliability of the turbine unit 5 as a whole and, as a whole, the air cycle refrigeration cooling system is improved. As described above, stable high-speed rotation, long-term durability, and reliability of the main shaft bearings 15 and 16 of the turbine unit 5 that are the bottleneck of the air cycle refrigeration cooling system are improved. It becomes possible.

1 is a cross-sectional view of a turbine unit in which a motor-integrated magnetic bearing device according to an embodiment of the present invention is incorporated. It is a block diagram which shows an example of the controller for magnetic bearings used for a motor integrated magnetic bearing apparatus. It is a block diagram which shows an example of the controller for motors used for a motor-integrated magnetic bearing apparatus. It is a systematic diagram of the air cycle refrigeration cooling system to which the turbine unit is applied. It is sectional drawing of a proposal example.

Explanation of symbols

2 ... Pre-compression means 3 ... First heat exchanger 5 ... Turbine unit 6 ... Compressor 6a ... Compressor impeller 7 ... Expansion turbine 7a ... Turbine impeller 8 ... Second heat exchanger 13 ... Main shafts 13a, 13b ... Thrust Plate 13aa, 13ba ... 鍔 14 ... Spindle housing 15, 16 ... Rolling bearing 17 ... Electromagnet 18 ... Sensor 19 ... Magnetic bearing controller 28 ... Motor 28a ... Motor rotor 28aa ... Permanent magnet 28b ... Motor stator

Claims (4)

A rolling bearing and a magnetic bearing are used in combination, the rolling bearing supports the radial load, the magnetic bearing supports one or both of the axial load and the bearing preload, and the electromagnet constituting the magnetic bearing is a strong force provided on the main shaft. It is attached to the spindle housing so as to face the flange-shaped thrust plate made of a magnetic material in a non-contact manner, two thrust plates are provided apart in the axial direction, and the motor rotor is composed of the two thrust plates. It is formed in a sandwiched space, an electromagnet target is formed on one side of the thrust plate, a permanent magnet for a motor rotor is arranged on the other side, and the permanent magnets are arranged in the circumferential direction so that the opposite poles face each other The motor stator is disposed so as to be sandwiched between the permanent magnets and attached to the spindle housing. Ri in response to the output of the sensor for detecting the axial force acting on the bearing, a controller for controlling the electromagnets,
The outer diameter of the thrust plate is such that the stiffness value of the synthetic spring formed by the rolling bearing and the rolling bearing support system is greater than the negative stiffness value of the synthetic spring formed by the electromagnet and the motor unit. A motor-integrated magnetic bearing device characterized in that a hook is formed on the part.   The motor-integrated magnetic bearing device according to claim 1, wherein the height of the flange formed on the thrust plate is equal to or higher than the thickness of the permanent magnet.   3. The compressor according to claim 1, wherein the main shaft includes a compressor side impeller and a turbine side impeller fitted to the common main shaft of the thrust plate and the motor rotor, and the motor power or the power generated by the turbine side impeller is selected. A motor-integrated magnetic bearing device applied to a compressor length turbine system for driving a compressor side impeller by one or both.   4. The compression / expansion turbine system to which the motor-integrated magnetic bearing device is applied according to claim 3, wherein the inflowing air is compressed by a compressor of the turbine unit, cooled by another heat exchanger, and by the expansion turbine of the turbine unit. An air cycle refrigeration cooling system that sequentially performs adiabatic expansion or compression by pre-compression means, cooling by a heat exchanger, compression by a compressor of a turbine unit, cooling by another heat exchanger, and adiabatic expansion of the turbine unit by an expansion turbine. Applied motor integrated magnetic bearing device.

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