JP2009050066A - Motor-integrated magnetic bearing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-integrated magnetic bearing apparatus which can improve long term durability of a roller bearing with respect to a load of a thrust load, can be made compact, can correspond to high speed rotation, can sufficiently cool a motor and can improve motor efficiency. <P>SOLUTION: The roller bearing and a magnetic bearing are used together. An electromagnet which constitutes the magnetic bearing faces a flange-like thrust board consisting of a ferromagnetic material, which is arranged in a main axis, without contact. A stator of an axial gap motor stores a motor coil 28ba in a case 28bb of a polymeric material. In the motor coil 28ba, a straight-angle wire is wound to respective layer parts 28ba1 and 28ba2 of two layers and both ends of winding, which become a winding start and a winding end, are disposed in an outer peripheral part. A cooling liquid circulation path 41 where cooling liquid flows so that cooling liquid is brought into contact with winding is arranged in the case 28bb, and the path is provided with a cooling liquid pass groove 41ba opened to the motor coil 28ba. Concaves and convexes 41baa are formed on a groove wall face. <P>COPYRIGHT: (C)2009,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. 12 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 plates 53a and 53b that are provided perpendicularly and coaxially to the main shaft 53 in a non-contact manner, and is magnetized according to the output of the sensor 58 that detects the force in the axial direction. It is controlled by a bearing controller 59. The motor 68 is of an axial gap type, and a motor rotor 68a is formed on the thrust plates 53a and 53b provided perpendicularly and coaxially to the main shaft 53, and a motor stator 68b is axially opposed to the motor rotor 68a. Arranged and configured. The motor rotor 68a includes the thrust plates 53a and 53b and a plurality of permanent magnets 68aa provided on the thrust plates 53a and 53b at an equal pitch in the circumferential direction. The motor stator 68b is configured by housing a motor coil 68ba in a case 68bb made of a polymer material.

  In the motor-integrated magnetic bearing device having the above-described configuration, the cooling liquid is placed in the case 68bb of the motor stator 68b so that the cooling liquid is in contact with the winding of the motor coil 68ba as shown in an enlarged sectional view in FIG. Is provided with a coolant circulation path 71. The coolant circulation path 71 has a coolant passage groove 71a opened facing the motor coil 68ba.

  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 bearings 55 and 56 with respect to the thrust load can be improved.

  Further, since the thrust plates 53a and 53b are used for mounting the target of the electromagnet 57 as a magnetic bearing and the permanent magnet 68aa for the motor rotor 68a, the length of the main shaft 53 is shortened, and the entire apparatus is made compact. Reduction of the natural frequency can be avoided and high-speed rotation is possible.

  Further, if the same thrust plates 53a and 53b are used to attach the target of the electromagnet 57 and the permanent magnet 68aa for the motor rotor 68a, the amount of heat generated in the motor stator 68b is very large, but the motor coil 68ba Since the coolant circulation path 71 for flowing the coolant to the case 68bb of the motor stator 68b is provided so that the coolant contacts the winding, an excellent cooling effect can be obtained, and the motor efficiency is lowered and the safety is deteriorated due to insufficient cooling. Can be avoided.

However, in the motor-integrated magnetic bearing device having the above-described configuration, when a normal round cross-section conducting wire as shown in FIG. 13A is used as the winding of the motor coil 68ba, the following problems occur.
(1) Since the winding wire portions 68baa and 68bab at the start and end of winding of the motor coil 68ba are drawn out and connected to the outer peripheral side of the motor coil 68ba as shown in FIG. 13A, they are connected to each other in the XIIB-XIIB in FIG. As shown in FIG. 13B showing a cross-sectional view taken along the arrow, the conductive wire portion crosses the end surface of the motor coil 68ba. Therefore, it is necessary to provide a slit for letting out the conductor portions 68baa and 68bab in the case 68bb of the motor stator 68b, and the thickness of the case 68bb increases. As a result, the gap between the motor coil 68ba of the motor stator 68b and the permanent magnet 68aa of the motor rotor 68a is expanded, resulting in a decrease in motor efficiency.
(2) Since the lead wire portion inside (center part) of the motor coil 68ba is not in direct contact with the coolant, the motor stator 68b is not sufficiently cooled by the coolant.

  An object of the present invention is to improve the long-term durability of a rolling bearing against a load of thrust load, to cope with downsizing and high-speed rotation, and to achieve sufficient motor cooling and motor efficiency improvement. It is to provide a body type magnetic bearing device.

A motor-integrated magnetic bearing device of the present invention includes a rolling bearing and a magnetic bearing that support a main shaft provided with a compressor impeller and a turbine impeller, and a motor that rotationally drives the main shaft, and the rolling bearing is radial. A load is supported, and the magnetic bearing supports one or both of an axial load and a bearing preload, and the electromagnet constituting the magnetic bearing is not in contact with a flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft. The motor-integrated magnetic bearing device is mounted on the spindle housing so that the rotor of the motor is installed on the spindle housing so as to face each other, and the motor stator is wound in a case made of a polymer material. The wire is wound in two layers using a flat wire, and both ends of the winding that becomes the winding start portion and winding end portion are arranged on the outer peripheral portion. The motor coil is housed, and a cooling fluid circulation path is provided in the case for flowing the cooling liquid so that the cooling liquid contacts the winding of the motor coil. The cooling fluid circulation path faces the motor coil. And has a coolant passage groove that is open, and is characterized in that irregularities are formed on the groove wall surface. The “flat conductor” is a conductor having a rectangular conductor cross section.
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, since the permanent magnet of the motor rotor is provided on the thrust plate facing the electromagnet of the magnetic bearing, the main shaft length is shortened by using the thrust plate of the magnetic bearing and the motor rotor, and the natural frequency is reduced. This can be avoided and enables low-vibration rotation during high-speed rotation.
The motor is of an axial gap type and has a large amount of heat generated in the motor stator, and cannot be sufficiently cooled by indirect cooling from the outside of the motor case as is done with a general motor. However, an excellent cooling effect can be obtained because the coolant circulation path for flowing the coolant into the motor stator is provided so that the coolant contacts the winding of the motor coil. The circulation path has a coolant passage groove that opens to face the motor coil, and the cross section of the path is reduced, so that when the same amount of coolant flows, the coolant flows at a higher speed, thus further cooling. Efficiency is improved. Further, the motor coil is wound in two layers using a flat wire as a winding, and both ends of the winding serving as a winding start portion and a winding end portion are disposed on the outer peripheral portion and accommodated in the motor case. The coolant flowing through the coolant passage groove of the liquid circulation path comes into contact with all the conductor portions of the motor coil, so that the entire coil can be cooled uniformly. Furthermore, since the unevenness is formed on the wall surface of the coolant passage groove, the coolant flow becomes turbulent and the cooling effect is further improved. Thereby, it is possible to avoid a reduction in motor efficiency and a deterioration in safety due to insufficient cooling. Since the motor case is made of a polymer material, it is easy to form a coolant circulation path such as a coolant passage groove, and since it is nonmagnetic, it does not affect the magnetic field.
Further, as described above, the motor coil is wound in two layers using a flat wire as a winding, and both ends of the winding serving as a winding start portion and a winding end portion are arranged on the outer peripheral portion and accommodated in the motor case. Therefore, it is not necessary to provide a slit in the motor case to escape both ends of the motor coil winding, and the thickness of the motor case can be reduced accordingly, and the gap between the motor coil and the motor rotor can be reduced, improving the motor efficiency. Can be made.

In the present invention, a plurality of the motor coils may be arranged in a common case on the same circumference, and a plurality of the coolant passage grooves may be provided in contact with the end surfaces of the coils.
Thus, when a plurality of cooling liquid passage grooves are provided facing the end face of each coil, the cooling liquid flows through each cooling liquid passage groove at a high speed, so that the cooling effect on the motor coil can be further enhanced. .

In the present invention, a plurality of the motor coils are arranged in a common case and arranged in a common case, and a coolant passage that constitutes the coolant circulation path is interposed between the two layers of each coil. A plurality of them may be provided.
Thus, the cooling effect with respect to a motor coil can be heightened more by interposing a cooling fluid passage way in the middle of two layers of each coil.

  In the present invention, the coolant may be oil or ethylene glycol. If it is oil or ethylene glycol, the coil coating will not be corroded even if it flows directly in contact with the coil.

  According to the present invention, in the compression-expansion turbine system, a compressor impeller and a turbine impeller are attached to the main shaft, and the compressor impeller is driven by one or both of motor power and power generated by the turbine impeller. It may be applied. 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, an expansion / compression turbine system to which the motor-integrated magnetic bearing device is applied is configured to compress the inflow air by a compressor of a turbine unit, compression by a heat exchanger, cooling by another heat exchanger, An air cycle refrigeration cooling system that sequentially performs adiabatic expansion by an expansion turbine of a unit or cooling by pre-compression means, compression by a compressor of the turbine unit, cooling by another heat exchanger, and adiabatic expansion by the expansion turbine of the turbine unit. It may be applied.
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, as a whole, the air cycle refrigeration cooling system can be 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 of the present invention includes a rolling bearing and a magnetic bearing that support a main shaft provided with a compressor impeller and a turbine impeller, and a motor that rotationally drives the main shaft, and the rolling bearing is radial. A load is supported, and the magnetic bearing supports one or both of an axial load and a bearing preload, and the electromagnet constituting the magnetic bearing is not in contact with a flange-shaped thrust plate made of a ferromagnetic material provided on the main shaft. The motor-integrated magnetic bearing device is mounted on the spindle housing so that the rotor of the motor is installed on the spindle housing so as to face each other, and the motor stator is wound in a case made of a polymer material. The wire is wound in two layers using a flat wire, and both ends of the winding that becomes the winding start portion and winding end portion are arranged on the outer peripheral portion. The motor coil is housed, and a cooling fluid circulation path is provided in the case for flowing the cooling liquid so that the cooling liquid contacts the winding of the motor coil. The cooling fluid circulation path faces the motor coil. Since it has a coolant passage groove that is open and has irregularities on the groove wall surface, it can improve the long-term durability of the rolling bearing against the load of thrust load, and it can cope with compactness and high speed rotation. In addition, sufficient motor cooling and motor efficiency can be improved.

  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 is installed on the spindle housing 14 so as to face the one surface of the thrust plate 13b located near the compressor 6 toward the compressor 6 side, with the electromagnet target being non-contacted. Is done.

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 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. A plurality of concentrated winding type motor coils 28ba are installed in the spindle housing 14. Specifically, as shown in FIG. 2 which is an exploded plan view, the motor stator 28b has a plurality (two in this case) of modules 28b1 and 28b2 in which a plurality of the motor coils 28ba are arranged in the circumferential direction and integrated with each other. It is divided into two parts. As a result, the motor stator 28b disposed between the two thrust plates 13a and 13b integral with the main shaft 13 can be incorporated as a component of the motor unit.
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 (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. 4 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 plates 13a and 13b shown in FIG. 1. Since only the attractive force acts, the direction of current is determined in advance by the diodes 34 and 35, and the two electromagnets 171 are used. , 172 are selectively driven.

  In the motor controller 29 of FIG. 5 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. A constant rotation control is performed by supplying a corresponding motor drive current from the motor drive circuit 39 to the motor coil 28ba of the motor stator 28b. The timing for switching the supply of the motor driving current to the motor coil 28ba is determined by the phase adjustment circuit 38 based on the output of the position sensor 40 provided in the motor stator 28b and detecting the passage of the permanent magnet 28aa of the motor rotor 28a. 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.

FIG. 6 shows a cross-sectional view of the half part of the motor 28 along the axial direction, and FIG. 7 shows a cross-sectional view of the partial module 28b1 of the motor stator 28b along the direction perpendicular to the axis. The motor stator 28b includes the plurality of motor coils 28ba and a polymer material case 28bb which is an insulating material that accommodates the motor coils 28ba. The case 28bb is provided for each of the modules 28b1 and 28b2 as described above.
As shown in a perspective view in FIG. 3 (A), the motor coil 28ba uses a rectangular conductive wire as its winding, and is wound on each of the two layer portions 28ba1 and 28ba2, and its winding start portion and winding end portion The winding ends 28baa and 28bab are arranged on the outer periphery. FIG. 3B shows the winding structure as a diagram. The first layer portion 28ba1 and the second layer portion 28ba2 are continuous on the inner periphery.

As shown in FIGS. 6 and 7, the case 28bb of the motor stator 28b has a coolant circulation path 41 through which the coolant 20 flows into the motor stator 28b so that the coolant 20 contacts the winding of the motor coil 28ba. Is provided. As the cooling liquid 20, for example, oil or ethylene glycol is used. When oil or ethylene glycol is used as the cooling liquid 20, even if the oil or ethylene glycol is caused to flow directly in contact with the motor coil 28ba, the coating of the motor coil 28ba is not corroded. The coolant circulation path 41 includes an inlet 41a to which the coolant 20 is supplied from the outside of the case 28bb, an in-case cooling path 41b provided in the case 28bb in communication with the inlet 41a, and this in-case cooling. And one or a plurality of discharge ports 41c provided in the path 41b. The inlet 41a and the outlet 41c are disposed on the outer periphery of the in-case cooling path 41b.
The in-case cooling path 41b has a coolant passage groove 41ba opened facing the motor coil 28ba. Specifically, the in-case cooling path 41b includes a cooling path outer peripheral part 41bb that is located on the outer periphery of the motor coil 28ba and extends in an arc shape, and stator radii on both end faces of the motor coil 28ba from the cooling path outer peripheral part 41bb. A plurality of radially arranged cooling fluid passage grooves 41ba provided along a portion extending in the direction, and a communication portion 41bc in which the inner ends in the stator radial direction of the respective cooling fluid passage grooves 41ba on both surfaces of the motor coil are communicated. . The coolant passage groove 41ba along both end faces of each motor coil 28b is opened along the surface of the motor coil 28ba, and the coolant flowing in the groove is in direct contact with the coil winding of the motor coil 28ba. A plurality of cooling path outer peripheral portions 41bb are provided side by side in the arc direction, and one of them (one in the center in the illustrated example) is provided with an inlet 41a in the cooling path outer peripheral portion 41bb, and the remaining (example shown in the figure). Then, the discharge port 41c is formed in the cooling path outer peripheral portion 41bb on the two sides.

  As shown in FIG. 8 showing a cross-sectional view taken along the line VIII-VIII in FIG. 7, irregularities 41baa are formed on the groove wall surface of the coolant passage groove 41ba. As shown in FIG. 3, the motor coil 28ba accommodated in the case 28bb is wound by using a flat conductive wire as a winding so as to overlap each of the two layer portions 28ba1 and 28ba2, and the winding start portion and the winding end portion. Since both winding ends 28baa and 28bab are arranged on the outer peripheral portion, the end faces of the motor coil 28ba are not traversed by the winding ends 28baa and 28bab as in the case of using a normal round cross-section conducting wire. There is no need to provide slits for escaping the winding ends 28baa and 28bab. As a result, the thickness of the case 28bb can be reduced accordingly.

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, the motor 28 is an axial gap type and generates a large amount of heat in the motor stator 28b, so that it is indirectly generated from the outside of the motor case as used in a general motor. Cooling is not enough. However, since the coolant circulation path 41 for flowing the coolant 20 into the motor stator 28b is provided so that the coolant 20 contacts the winding of the motor coil 28ba, effective cooling is performed. In addition, since the coolant circulation path 41 flows through the cooling passage groove 41ba that opens to face the motor coil 28ba, if the entire flow rate is the same, it flows in a narrow channel cross section and the flow rate is high. It becomes. Therefore, it can cool more efficiently.
Further, the motor coil 28ba is wound around each of the two layer portions 28ba1 and 28ba2 using a flat wire as a winding, and winding ends 28baa and 28bab serving as winding start portions and winding end portions are arranged on the outer peripheral portion. Since it is accommodated in 28bb, the coolant flowing through the coolant passage groove 41ba of the coolant circulation path 41 comes into contact with all the conductor portions of the motor coil 28ba, so that the entire coil can be cooled uniformly. Furthermore, since the unevenness 41baa is formed on the wall surface of the coolant passage groove 41ba, the coolant flow becomes turbulent and a more sufficient cooling effect is obtained. Thereby, it is possible to avoid a reduction in motor efficiency and a deterioration in safety due to insufficient cooling. Further, since the case 28bb of the motor stator 28b is made of a polymer material, it is easy to form the coolant circulation path 41 such as the coolant passage groove 41ba and the like, and since it is a non-magnetic material, it has an influence on the magnetic field. Absent.

  Further, the motor coil 28ba is wound around each of the two layer portions 28ba1 and 28ba2 using a flat wire as a winding, and winding both ends 28baa and 28bab serving as the winding start portion and winding end portion are arranged on the outer peripheral portion. Since the case 28bb is accommodated in the case 28bb, it is not necessary to provide the case 28bb with slits for releasing the winding ends 28baa and 28ba of the motor coil 28ba, and the thickness of the case 28bb can be reduced accordingly. As a result, the gap between the motor coil 28ba and the permanent magnet 28aa of the motor rotor 28a can be narrowed, and the motor efficiency can be improved.

In the above embodiment, as shown in FIG. 8, the coolant passage 41bd constituting the coolant circulation path 41 is interposed between the two layer portions 28ba1 and 28ba2 of the two layers of each motor coil 28ba. A plurality of them may be provided. These coolant passages 41bd are formed, for example, by providing a space by disposing a spacer member 49 between the two layer portions 28ba1 and 28ba2, and using the space as the coolant passage 41d. Each coolant passage 41bd communicates with the cooling path outer periphery 41bb and the communication part 41bc.
As described above, when the coolant passage 41d is provided in the middle of the two layer portions 28ba1 and 28ba2 of the motor coil 28ba, the cooling effect can be further improved. Other configurations and effects in this embodiment are the same as those in the first embodiment shown in FIGS. When the intermediate coolant passage 41d is provided, the coolant passage groove 41ba may be omitted.

  FIG. 10 shows another embodiment of the turbine unit 5. In the embodiment shown in FIG. 1, the turbine unit 5 has only one flange-like thrust plate made of a ferromagnetic material that is perpendicular and coaxial with the main shaft 13, and this thrust plate 13a is used as an electromagnet target. A pair of left and right electromagnets 17 are arranged on the spindle housing 14 so as to face both surfaces without contact.

The motor 28 includes a motor rotor 28a provided on the main shaft 13 and a motor stator 28b facing the motor rotor 28a in the axial direction. A pair of left and right motor rotors 28a is configured by disposing permanent magnets 28aa arranged at equal pitches in the circumferential direction on the outer diameter side of the thrust plate 13a on the both sides of the thrust plate 13a. 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. The thrust plate 13a also serves as a back yoke for the permanent magnet 28aa.
The motor stator 28b includes a pair of left and right motors installed on the spindle housing 14 so as to face the motor rotors 28a on both sides of the thrust plate 13a in a non-contact manner. In this way, the two left and right motors 28 sandwiching the thrust plate 13a rotate the main shaft 13 by the magnetic force acting between the motor rotor 28a and the motor stator 28b. Other configurations are the same as those of the embodiment of FIGS. 1 to 8, and the description thereof is omitted here.

  FIG. 11 shows the overall configuration of an air cycle refrigeration cooling system using the turbine unit 5 shown in FIG. 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 a first embodiment of the present invention is incorporated. FIG. 3 is an exploded plan view of a motor stator in the turbine unit. (A) is a perspective view of the motor coil in a motor stator, (B) is a perspective view which shows the motor coil as a diagram. 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 half section view along the axial direction of the motor in the motor-integrated magnetic bearing device. It is sectional drawing which follows a direction perpendicular | vertical to the axis | shaft of a partial module of a motor stator. It is VIII-VIII arrow sectional drawing in FIG. It is sectional drawing of the motor stator equivalent to VIII-VIII arrow sectional drawing of FIG. 7 in other embodiment of this invention. It is sectional drawing of the turbine unit with which the motor-integrated magnetic bearing apparatus concerning other embodiment of this invention was integrated. FIG. 2 is a system diagram of an air cycle refrigeration cooling system to which the turbine unit of FIG. 1 is applied. It is sectional drawing of a proposal example. (A) is a front view of a motor coil when a round cross-section conducting wire is used for the motor coil in the proposed example, and (B) is a cross-sectional view taken along arrow XIIB-XIIB in (A). It is a fragmentary sectional view in 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 14 ... Spindle housing 15, 16 ... Rolling bearing 17 ... Electromagnet 20 ... Coolant 28 ... Axial gap motor 28a ... Motor rotor 28aa ... Permanent magnet 28b ... Motor stator 28ba ... Motor coils 28baa, 28bb ... Winding ends 28bb of the motor coil ... Case 41 ... Cooling liquid circulation path 41ba ... Cooling liquid passage groove 41baa ... Concavity and convexity 41bd of cooling liquid passage groove ... Cooling liquid passage path 41d

Claims (6)

A rolling bearing and a magnetic bearing that support a main shaft provided with a compressor wheel and a turbine wheel, and a motor that rotationally drives the main shaft; the rolling bearing supports a radial load; and the magnetic bearing is an axial load. The electromagnet that supports either or both of the bearing preloads and that constitutes the magnetic bearing is attached to 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, A motor-integrated magnetic bearing device in which a rotor of the motor is installed in the spindle housing,
The motor stator is a motor comprising a case made of a polymer material, in which windings are wound in two layers using a flat wire for winding, and both ends of the winding serving as a winding start part and a winding end part are arranged on the outer peripheral part. In the case, a cooling liquid circulation path is provided in the case to flow the cooling liquid so that the cooling liquid contacts the winding of the motor coil, and the cooling liquid circulation path faces the motor coil. A motor-integrated magnetic bearing device having a coolant passage groove that is open and having an uneven surface formed on the groove wall surface.   2. The motor-integrated magnetic bearing according to claim 1, wherein a plurality of the motor coils are arranged on the same circumference and provided in a common case, and a plurality of the coolant passage grooves are provided in contact with the end surfaces of the coils. apparatus.   3. The motor coil according to claim 1, wherein a plurality of the motor coils are arranged in a common case on the same circumference, and the coolant passages constituting the coolant circulation path are provided in two layers of each of the coils. A motor-integrated magnetic bearing device provided in plural in the middle of the motor.   4. The motor-integrated magnetic bearing device according to claim 1, wherein the coolant is oil or ethylene glycol.   5. The compressor impeller according to claim 1, wherein a compressor impeller and a turbine impeller are attached to the main shaft, and either one or both of motor power and power generated by the turbine impeller are used. A motor-integrated magnetic bearing device that is applied to a compression / expansion turbine system that drives a motor. 6. The expansion / compression turbine system to which the motor-integrated magnetic bearing device is applied according to claim 5, wherein the inflow air is compressed by a compressor of a turbine unit, compressed by a heat exchanger, cooled by another heat exchanger, Air cycle refrigeration cooling system that sequentially performs adiabatic expansion by an expansion turbine of a turbine unit, cooling by a pre-compression means, compression by a compressor of the turbine unit, cooling by another heat exchanger, adiabatic expansion of the turbine unit by an expansion turbine A motor-integrated magnetic bearing device applied to the motor.

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