JP2008038970A - Motor integrated magnetic bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor integrated magnetic bearing device capable of improving long-term durability of a roller bearing under a load of thrust loading and also capable of enabling the high-speed rotation of a main shaft. <P>SOLUTION: The motor integrated magnetic bearing device uses roller bearings 15 and 16 jointly with a magnetic bearing, and the roller bearings 15, 16 support the radial load and the magnetic bearing supports either axial load or bearing pre-load or both. Two thrust plates 13a and 13b are disposed axially at a distance and the two thrust plates 13a and 13b have an electromagnetic target in one side and a permanent magnet 28aa for a motor rotor 28a in the other side. A motor stator 28b is arranged so as to be clipped by the permanent magnet 28aa. The motor 28 is an axial gap type coreless motor. The main shaft 13 is split into two between the two thrust plates 13a and 13b and both main shaft splits are united together. <P>COPYRIGHT: (C)2008,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 present inventors have developed a motor-integrated magnetic bearing device as shown in FIG. 6 as a solution to the above problem. 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 a compressor impeller 46a of the compressor 46 and a 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 disposed so as to face the thrust plate 53a that is perpendicular and coaxial with the main shaft 53 in a non-contact manner, and is used for a magnetic bearing according to the output of the sensor 58 that detects the axial force. It is controlled by the controller 59. The motor 68 is of an axial gap type, and a motor rotor 68a is formed on another thrust plate 53b provided perpendicularly and coaxially to the main shaft 53, and a motor stator 68b is disposed so as to face the motor rotor 68a in the axial direction. Configured. 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 configured as described above, a magnetic bearing unit is configured by arranging two left and right electromagnets sandwiching one thrust plate provided on the main shaft 53, and is provided separately on the main shaft 53. Since the motor unit is configured independently of the magnetic bearing unit by disposing the left and right axial gap type motors 68 with one thrust plate interposed therebetween, the shaft length of the main shaft 53 is increased, and the natural frequency is increased. There is a problem that it is difficult to rotate at high speed.

  In order to solve such a problem, two thrust plates for providing an electromagnetic target of a magnetic bearing are provided on the main shaft, a stator in an axial gap type motor is disposed between the two thrust plates, and a motor rotor is provided on both thrust plates. The thing which provided the magnet used as this was devised (Japanese Patent Application No. 2005-356035).

  However, when two thrust plates are provided on the main shaft, the motor cannot be assembled. Further, since the distance between the two thrust plates is narrow, it is difficult to attach the permanent magnet for the motor rotor attached to the thrust plate. When the motor stator is divided, assembly is possible. However, since the motor stator has a motor coil, the structure becomes complicated if the motor stator is divided. Even if the motor stator is divided, the difficulty of attaching the permanent magnet to the thrust plate cannot be solved. For this reason, an attempt was made to enable the assembly of the motor by configuring the thrust plate with a ring-shaped plate separate from the main shaft and fitting the thrust plate to the main shaft. However, since the main shaft of this type of turbine unit rotates at a high speed of, for example, 80 to 100,000 rpm, the structure in which the thrust plate is fitted as described above lacks the strength of the joint between the thrust plate and the main shaft.

  An object of the present invention is to improve the long-term durability of a rolling bearing against a load of thrust load, to enable high-speed rotation of the main shaft, and to assembling problems due to a structure using two thrust plates It is an object to provide a motor-integrated magnetic bearing device that can solve the above-mentioned problem without incurring the problem of insufficient strength during high-speed rotation.

  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. These two thrust plates have an electromagnet target formed on one side, a permanent magnet for the motor rotor is disposed on the other side, and the permanent magnet for the motor rotor is disposed on the opposite surface of the two thrust plates. The permanent magnets are arranged at an equal pitch in the circumferential direction so that the different poles face each other, and the motors are sandwiched between the permanent magnets. And an axial gap coreless motor that rotates a main shaft by a Lorentz force between the motor rotor and the motor stator, and the main shaft is the two sheets. It is divided into two parts between thrust plates, and both main shaft divided bodies are combined with each other.

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 when only the magnetic bearing is supported 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 have 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 addition, because the motor stator is disposed between the two thrust plates of the main shaft, the device cannot be assembled if both the motor stator and the main shaft are integral members, but the main shaft is divided into two parts between the two thrust plates. In addition, since both the main shaft divided bodies are coupled to each other, the motor can be assembled such that an integral motor stator is interposed between the two thrust plates. In addition, since the main shaft is divided between the two thrust plates, even if the gap between these thrust plates is narrow, it is possible to easily attach the permanent magnets that serve as motor rotors attached to both thrust plates to the thrust plates by attaching them. it can. Unlike the case where the motor stator has a divided structure, the main shaft has a divided structure. Even if the main shaft rotates at high speed, the main shaft itself has a split structure that is divided between the two thrust plates. Unlike the case where the thrust plate is divided from the main shaft, a solid coupling structure can be designed freely. In addition, it is possible to solve the problem of insufficient strength at the connecting portion of the main spindle split part during high-speed rotation.

In the motor-integrated magnetic bearing device according to the present invention, one of the spindle divided bodies has a fitting convex portion at the axial center of the end face serving as the split surface, and the other spindle split body is fitted to the end face serving as the split face. It has a fitting recess that fits on the outer periphery of the mating convex part, and both spindle split bodies are abutted between the peripheral surface where the fitting convex part and the fitting concave part are fitted, and the end surface that becomes the split surface, It may be constrained in the radial direction and the axial direction, and may be coupled to each other by a bolt at the axial center.
In this way, both main shaft divided bodies are provided with a fitting convex portion and a fitting concave portion to form a so-called stamped joint, and the end face butting surface that becomes the split surface and the fitting surface between the fitting convex portion and the fitting concave portion. Therefore, both main spindle divided bodies can be firmly coupled.

  In this invention, the compressor side impeller and the turbine side impeller are fitted to the same main shaft as the thrust plate and the motor rotor, and the compressor side impeller is driven by one or both of the motor power and the power generated by the turbine side impeller. It may be applied to a compression / expansion turbine system. 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 compressing the inflow air by a compressor of the turbine unit, cooling by another heat exchanger, and insulating the turbine unit by the expansion turbine. Application to an air cycle refrigeration cooling system that performs expansion or compression by means of pre-compression, 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. It may be what was done.
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 stabilized in the compression-expansion turbine system while maintaining an appropriate clearance between the impellers. 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. These two thrust plates have an electromagnet target formed on one side, a permanent magnet for the motor rotor is disposed on the other side, and the permanent magnet for the motor rotor is disposed on the opposite surface of the two thrust plates. The permanent magnets are arranged at an equal pitch in the circumferential direction so that the different poles face each other, and the motors are sandwiched between the permanent magnets. Is disposed on a spindle housing, and has a coreless motor of a salcel axial gap type that rotates a main shaft by Lorentz force between the motor rotor and the motor stator, and the motor stator is a concentrated winding system Therefore, the long-term durability of the rolling bearing against the thrust load can be improved, and the main shaft can be rotated at high speed. In addition, since the main shaft is divided into two parts between the two thrust plates and the two main shaft divided bodies are coupled to each other, the problem of assembling due to the structure using the two thrust plates can be reduced. It can be solved without causing the problem of insufficient strength.

  A first 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 a 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 the main shaft 13 with a plurality of bearings 15 and 16 in the radial direction, and either or both of the axial load and the bearing preload applied to the main shaft 13 are magnetic bearings. An axial gap motor 28 that is supported by an electromagnet 17 and that rotates 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 supporting force of the electromagnet 17 in accordance with the output of the sensor 18, and the electromagnet 17. A motor controller 29 for controlling the motor 28;
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 are configured. 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. 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 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.

  2, the main shaft 13 is divided into two main shaft divided bodies 13A and 13B between two thrust plates 13a and 13b, and both main shaft divided bodies 13A and 13B are coupled to each other. It is supposed to be one. One main shaft divided body 13A has a round shaft-shaped fitting convex portion 13Aa at the axial center of the end surface S1 serving as a divided surface, and the other main shaft divided body 13B is fitted to the end surface S1 used as the divided surface. It has circular fitting recessed part 13Ba fitted to the outer periphery of convex part 13Aa. Both main shaft split bodies 13A and 13B are constrained in the radial direction and the axial direction by the fitting of the fitting convex portion 13Aa and the fitting concave portion 13Ba on the circumferential surface S2 and the butting of the end surface S1 serving as the divided surface. And connected to each other by a bolt 40 at the axial center. The bolt 40 is a double-cut bolt, and is formed at the center of the bottom surface of the fitting recess 13Ba of the other spindle split body 13B and the screw hole 41 formed at the center of the front end face of the fitting projection 13Aa of one spindle split body 13A. The screw hole 42 is screwed. Each of the spindle divided bodies 13A and 13B is subjected to heat treatment for hardening such as quenching of steel, and the bolt 40 is made of raw steel that is not subjected to heat treatment for hardening. ing.

  The opposing surfaces of the thrust plates 13a, 13b of the main shaft division bodies 13A, 13B are shaped to have an annular recess 43 between the vicinity of the center and the outer peripheral edge, and the motor rotor 28a is configured in the recess 43. A permanent magnet 28aa is attached by adhesion or the like.

  In FIG. 1, bearings 15 and 16 for supporting the main shaft 13 are rolling bearings and have a function of regulating the axial position, and for example, deep groove ball bearings or angular ball bearings are 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 on the inner diameter surface of the spindle housing 14 in the axial direction, 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 (electromagnet 17 and motor 28). ) Formed in parallel. In this spring system, the composite spring formed by the bearings 15 and 16 and the support system of these bearings has rigidity acting in proportion to the amount of displacement in the direction opposite to the displaced direction, while the electromagnet 17 and The combined spring formed by the motor 28 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
If the stiffness value of the composite spring by the bearing etc. <the negative stiffness value of the composite spring by the electromagnet / motor ... (1), the phase of the mechanical system is delayed by 180 ° and the system becomes unstable, so the electromagnet 17 is controlled. In the magnetic bearing controller 19, the phase compensation circuit needs to be added in advance, and the configuration of the controller 19 becomes complicated.

Therefore, in the motor-integrated magnetic bearing device of this embodiment, the above-described rigidity relationship of the two composite springs is expressed as follows:
Rigidity value of the combined spring by the bearing or the like> Negative rigidity value of the combined spring by the electromagnet / motor (2). 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 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. 3 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 171 and 172 in each direction via diodes 34 and 35, respectively. The electromagnets 171 and 172 are a pair of electromagnets 17 opposed to the thrust plate 13a shown in FIG. 1, and only the attraction force acts on them. Is driven selectively.

  In the motor controller 29 of FIG. 4 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 rolling type bearings 15 and 16, the axial direction position of the main shaft 13 is regulated to some extent by the restriction function of the axial direction position of the rolling bearing, and each impeller 6a, 7a and 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. Can be used in an optimum state against the thrust force according to the bearing specifications.
In particular, two electromagnets 17 are arranged on the axially outer side of two thrust plates 13a and 13b provided on the main shaft 13 side by side in the axial direction to constitute a magnetic bearing unit, and are sandwiched between the thrust plates 13a and 13b. By arranging the axial gap type motor 28 at the position to constitute the motor unit, the magnetic bearing unit and the motor unit have a compact integrated structure. Therefore, the shaft length of the main shaft 53 can be shortened, and the natural vibration of the main shaft 13 can be reduced accordingly. The number increases, and the main shaft 13 can be rotated at high speed.

Further, in this motor-integrated magnetic bearing device, since the motor stator 28b is disposed between the two thrust plates 13a and 13b of the main shaft 13, both the motor stator 28b and the main shaft 13 are integrated members. As shown in FIG. 2, the main shaft 13 is divided into two parts between the two thrust plates 13a and 13b, and both main shaft divided bodies 13A and 13B are combined with each other. The motor can be assembled so that the integral motor stator 28b is interposed between the thrust plates 13a and 13b. Further, since the main shaft 13 is divided between the two thrust plates 13a and 13b, the permanent magnet 28aa serving as the motor rotor 28a attached to the thrust plates 13a and 13b can be obtained even if the gap between the thrust plates 13a and 13b is narrow. It can be easily attached to the thrust plates 13a and 13b. In other words, the permanent magnet 28aa can be attached with the main spindle segments 13A and 13B separated from each other, and the permanent magnet 28aa can be attached regardless of the size of the gap between the thrust plates 13a and 13b.
Unlike the case where the motor stator 28b has a divided structure, the main shaft 13 has a divided structure. Even if the main shaft 13 rotates at a high speed, the main shaft 13 itself has a divided structure that is divided between two thrust plates. Therefore, unlike the case where the thrust plates 13a and 13b are divided from the main shaft 13, a firm connection is achieved. The structure can be designed freely, and it is possible to solve the problem of insufficient strength at the connecting part of the main spindle split part during high-speed rotation.

In this embodiment, both main shaft divided bodies 13A and 13B are provided with fitting convex portions 13Aa and fitting concave portions 13Ba to form a so-called stamped joint, and the abutting surface of the end surface S1 which becomes a divided surface, and the fitting convex portions 13Aa. , The two main shaft split bodies 13A and 13B can be firmly coupled to each other because the two parts with the circumferential surface S2 to which the fitting recess 13Ba is fitted are restrained and fastened with the bolt 40.
The bolt 40 may be provided integrally with any one of the main shaft divided bodies 13A and 13B. However, if the main shaft divided bodies 13A and 13B are separate parts, the material of the bolt 40 can be freely selected. it can. In this example, the main shaft 13 is subjected to heat treatment for improving hardness such as quenching in order to ensure rigidity, but when the main shaft divided bodies 13A and 13B and the bolt 40 are heat-treated, the bolt portion becomes brittle. There is a risk of shortage. However, since the bolt 40 is a non-quenched material as a separate member, the problem of insufficient brittleness is solved, and reliable fastening without the problem of unexpected breakage of the bolt 40 can be performed.

  FIG. 5 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, and circulates air from an air intake port 1a to a discharge port 1b respectively opened in the space to be cooled 10. 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 sectional drawing of the main axis | shaft in the same turbine unit. 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 Plates 13A, 13B ... Spindle segment 13Aa ... Fitting protrusion 13Ba ... Fitting recess 14 ... Spindle housings 15, 16 ... Rolling bearing 17 ... Electromagnet 18 ... Sensor 19 ... Magnetic bearing controller 28 ... Coreless motor 28a ... Motor rotor 28aa ... Permanent magnet 28b ... motor stator 28ba ... coil 40 ... bolt S1 ... end face S2 ... circumferential surface

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 magnetic material in a non-contact manner, and the two thrust plates are provided apart in the axial direction, and these two thrust plates are electromagnets on one side. A target is formed, and a permanent magnet for the motor rotor is disposed on the other surface, the permanent magnet for the motor rotor is disposed on the opposing surfaces of the two thrust plates, and the permanent magnets have different polarities from each other. A motor stator is arranged on the spindle housing so as to be opposed to each other with a constant pitch in the circumferential direction and sandwiched between the permanent magnets. And attached, it is one having a coreless motor of the axial gap type rotating the spindle by the Lorentz force between the motor rotor and the motor stator,
The motor-integrated magnetic bearing device, wherein the main shaft is divided into two parts between the two thrust plates, and both main shaft divided bodies are coupled to each other.   In Claim 1, one main shaft split body has a fitting convex part in the axial center part of the end surface used as a split surface, and the other main shaft split body fits in the outer periphery of the fitting convex part on the end surface used as a split surface. The two main shaft split bodies are constrained in the radial direction and the axial direction by abutment of the peripheral surface where the fitting convex portion and the fitting concave portion are fitted with the end face serving as the divided surface. And a motor-integrated magnetic bearing device coupled to each other by a bolt at the axial center.   In Claim 1 or Claim 2, the compressor side impeller and the turbine side impeller are fitted to a main shaft common to the thrust plate and the motor rotor, and either or both of the motor power and the power generated by the turbine side impeller are used. A motor-integrated magnetic bearing device that is applied to a compression / expansion turbine system for driving a compressor side impeller. 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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