JP2008185110A - Magnetic bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing device having simple and inexpensive construction accurately controlling a magnetic bearing without being influenced by the unbalance of thermal expansion and a leakage flux of an electromagnet while improving the long-time durability of a rolling bearing to a thrust load. <P>SOLUTION: A force detecting sensor unit 18 consists of a pair of ring-shaped sensor targets 31, 32 sandwiching both end faces of an outer ring 16b of the rolling bearing 16, a pair of plate springs 33, 34 supporting the sensor targets 31, 32, and a gap sensor 35 for detecting a gap between the sensor targets 31, 32. A controller 19 has a correction amount computing means and an adding means. The correction amount computing means computes a correction amount corresponding to a current value detected by a current detecting means or a leakage flux detected by a leakage flux detecting means, and the adding means adds the correction amount to the output of the force detecting sensor unit. <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 magnetic bearing device.

  The use of air as the refrigerant in the refrigeration cooling system is preferable in terms of environmental protection and safety compared to the case of using chlorofluorocarbon or ammonia gas, but is insufficient in terms of characteristics as energy efficiency. However, when used in a facility that can directly blow in air as a refrigerant, such as in a freezer warehouse, the total cost can be reduced to the same level as existing systems by taking measures such as omitting the internal fan and defrost. there is a possibility. At present, the use of chlorofluorocarbon as a refrigerant is already restricted from the environmental viewpoint, and it is desired to avoid using other refrigerant gas as much as possible. Therefore, an air cycle refrigeration cooling system that uses air as a refrigerant has been proposed for the above-described applications (for example, Patent Document 1 and Non-Patent Document 1).

Further, it is stated that the theoretical efficiency of air cooling is equal to or higher than that of chlorofluorocarbon or ammonia gas in a deep coal region of −30 ° C. to −60 ° C. (Non-patent Document 1). 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, Non-Patent Document 1).

In addition, as a turbine compressor which processes a process gas, a turbine impeller is attached to one end of a 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 are 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 Magazine, Nikkei Mechanical, “Cooling the Air with Air”, published November 13, 1995, no 467, pp. 46-52

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. This turbine unit improves the efficiency of the air cycle refrigerator by being able to drive the compressor impeller with power generated by the expansion turbine.

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 techniques disclosed in Patent Document 1 and Non-Patent Document 2 have not yet been solved for the deterioration of the long-term durability of the bearing against the load of the thrust load under high-speed rotation.

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

Accordingly, the inventors of the present invention have developed a magnetic bearing device as shown in FIG. 14 (Japanese Patent Application No. 2006-262500) as a solution to the above-described problems. This magnetic bearing device is a turbine unit for air cycle refrigeration cooling in which a compressor impeller 66a of a compressor 66 and a turbine impeller 67a of an expansion turbine 67 are attached to both ends of a main shaft 73. Thus, either one or both of the axial load and the bearing preload are supported by the electromagnet 77, and the compressor impeller 66a is rotationally driven by the driving force of the turbine impeller 67a. The electromagnet 77 is arranged so as to face the thrust plate 73a provided perpendicularly and coaxially with the main shaft 73 in a non-contact manner, and according to the output of the force detection sensor unit 78 for detecting the force in the axial direction, the magnetic bearing controller 79. It is controlled by.
As shown in an enlarged view in FIG. 15, the force detection sensor unit 78 supports a pair of ring-shaped sensor targets 91 and 92 sandwiching both end surfaces of the outer ring 76 b of the rolling bearing 76 and the sensor targets 91 and 92. And a gap sensor 95 for detecting a gap with respect to the sensor targets 91 and 92. The leaf springs 93 and 94 are attached to the spindle housing 74 at the outer diameter side portion in the main shaft radial direction, and the sensor targets 91 and 92 are attached to the inner diameter side portions of the leaf springs 93 and 94. The spindle housing 74 includes a bearing housing 74b that supports the outer ring 76b of the rolling bearing 76 in an axial direction so as to be movable in the axial direction, and a spindle housing body 74a coupled to the bearing housing 74b. 93 and 94 are attached to the bearing housing 74b. In addition, a plurality of gap sensors 95 are arranged at equal positions in the circumferential direction, for example, as shown in FIG. 16 on each side of the bearing housing 74b facing the sensor targets 91 and 92.

  The force detection sensor unit 78 detects a gap between the gap sensor 95 and the sensor targets 91 and 92 that change according to the thrust force acting on the main shaft 73 by the gap sensor 95, and the detected value is detected by the magnetic bearing controller 79. Converted to thrust force.

  According to the magnetic bearing device having the above configuration, since the thrust force applied to the main shaft 73 is supported by the electromagnet 77, the thrust force acting on the rolling bearings 75 and 76 can be reduced while suppressing an increase in torque without contact. As a result, the minute gaps between the respective impellers 66a and 67a and the housings 66b and 67b can be kept constant, and the long-term durability of the rolling bearings 75 and 76 with respect to the thrust load can be improved.

  However, in the magnetic bearing device configured as described above, in the force detection sensor unit 78, the sensor targets 91 and 92 facing each other by the plurality of gap sensors 95 including reluctance sensors disposed on both sides of the bearing housing 74b in the spindle housing 74. Therefore, there is a problem that the mounting accuracy of the gap sensor 95 becomes strict and the processing of the bearing housing 74b becomes expensive. Further, if a high magnetic permeability material is used for the bearing housing 74b in order to improve the detection sensitivity, there is a problem that the cost is further increased.

  Further, in the force detection sensor unit 78, when the gap sensor 95 is composed of, for example, a reluctance sensor as described above, if the gap sensor 95 is arranged in the immediate vicinity of the electromagnet 77, the detection signal of the gap sensor 95 is generated by the leakage magnetic flux of the electromagnet 77. Drift will occur. Since the influence of the drift varies depending on the difference in distance from the electromagnet 77, the influence of the drift cannot be canceled by differential calculation. Therefore, there is a problem that the accuracy of detecting the gap fluctuation by the force detection sensor unit 78 is lowered.

  An object of the present invention is to improve the long-term durability of a rolling bearing against a thrust load, and with a simple and inexpensive configuration, the magnetic bearing is not affected by the imbalance of thermal expansion or the leakage flux of an electromagnet. It is an object to provide a magnetic bearing device capable of accurately controlling the above.

The magnetic bearing device of the present invention uses both a rolling bearing and a magnetic bearing, 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 is perpendicular to the main shaft and An electromagnet is attached to the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided coaxially in a non-contact manner, and according to the output of a force detection sensor unit that detects a force in the axial direction. A magnetic bearing device having a controller for controlling the motor is characterized by having the following configuration.
The force detection sensor unit includes a pair of ring-shaped sensor targets sandwiching both end surfaces of an outer ring of a rolling bearing, a pair of leaf springs that support each of the sensor targets, and a gap sensor that detects a gap with respect to the sensor target. The leaf spring is attached to the spindle housing at the outer diameter side portion in the main shaft radial direction and the sensor target is attached to the inner diameter side portion.
A current detection means for detecting a current flowing through the electromagnet or a leakage flux detection means for detecting a leakage magnetic flux amount of the electromagnet is provided, and a current value detected by the current detection means or the leakage flux is provided in a controller for controlling the electromagnet. Correction amount calculation means for calculating a correction amount corresponding to the leakage magnetic flux detected by the detection means, and addition means for adding the correction amount calculated by the correction amount calculation means to the output of the force detection sensor unit are provided.
According to this configuration, since the rolling bearing and the magnetic bearing are used in combination, the rolling bearing supports the radial load, and the magnetic bearing supports one or both of the axial load bearing preloads. 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.
Further, in this magnetic bearing device, the electromagnet is controlled by a controller in accordance with the output of the force detection sensor unit that detects the axial force of the main shaft, and the force detection sensor unit is connected to both end faces of the outer ring of the rolling bearing. A pair of ring-shaped sensor targets, a pair of leaf springs that support each of the sensor targets, and a gap sensor that detects a gap with respect to the sensor target, the leaf springs having an outer diameter in the main shaft radial direction. Since the side portion is attached to the spindle housing and the sensor target is attached to the inner diameter side portion, the magnetic bearing can be accurately controlled without being affected by thermal expansion imbalance.
In particular, the current detection means for detecting the current flowing through the electromagnet or the leakage flux detection means for detecting the leakage magnetic flux amount of the electromagnet is provided, and the current value detected by the current detection means or the leakage is provided in the controller for controlling the electromagnet. Correction amount calculation means for calculating a correction amount corresponding to the leakage magnetic flux detected by the magnetic flux detection means, and addition means for adding the correction amount calculated by the correction amount calculation means to the output of the force detection sensor unit are provided. Therefore, even if drift occurs in the detection signal of the gap sensor due to the leakage flux of the electromagnet, the influence of the leakage flux can be canceled and the output accuracy of the force detection sensor unit can be improved. As a result, the magnetic bearing can be accurately controlled with a simple and inexpensive configuration without being affected by imbalance of thermal expansion or leakage magnetic flux of the electromagnet.

  In the present invention, the gap sensor is a magnetic gap sensor in which a ring-shaped groove centered on a rotor axis is formed in a spindle housing, and a ring-shaped coil is inserted into the groove. The spindle housing may also serve as a yoke portion that forms a magnetic path around the spindle housing. In this configuration, the sensor sensitivity can be improved by enlarging the area of the magnetic path, so the sensor sensitivity can be improved without tightening the accuracy of mounting the gap sensor to the spindle housing or using a high permeability material in the spindle housing. The magnetic bearing can be controlled more accurately.

The present invention may be applied to a compression / expansion turbine system in which a compressor side impeller and a turbine side impeller are attached to the main shaft, and the compressor impeller is driven by power generated by the turbine impeller.
In the case of this configuration, a stable high-speed rotation of the main shaft can be obtained while maintaining an appropriate gap between the impellers, and the long-term durability and life of the bearing can be improved.

In this invention, a motor-integrated magnetic bearing device in which the main shaft is provided with the thrust plate and a motor rotor, and a compressor-side impeller and a turbine-side impeller are attached to the main shaft, and motor power and power generated by the turbine-side impeller are provided. It is good also as what is applied to the compression expansion turbine system which drives a compressor side impeller by either or both of these.
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. Further, since the main shaft is driven by providing a motor, it is not necessary to provide pre-compression means such as a blower before the compressor.

In the present invention, the compression / expansion turbine system to which the magnetic bearing device is applied has an air cycle for sequentially performing compression by pre-compression means, cooling by a heat exchanger, and adiabatic expansion by the expansion turbine of the turbine unit for the incoming air. It may be applied to a refrigeration cooling system.
When a compression / expansion turbine system to which this magnetic bearing device is applied is applied to such an air cycle refrigeration / cooling system, a stable high-speed rotation of the main shaft can be obtained while maintaining an appropriate clearance between the impellers in the compression / expansion turbine system. The long-term durability of the bearing and the improvement of the service life of the bearing can be obtained, so that the main shaft bearing of the compression / expansion turbine system, which is the bottleneck of the air cycle refrigeration cooling system as a whole, can be obtained. Since stable high-speed rotation, long-term durability and reliability are improved, the air cycle refrigeration cooling system can be put to practical use.

  The magnetic bearing device of the present invention uses both a rolling bearing and a magnetic bearing, 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 is perpendicular to the main shaft and An electromagnet is attached to the spindle housing so as to face the flange-shaped thrust plate made of a ferromagnetic material provided coaxially in a non-contact manner, and according to the output of a force detection sensor unit that detects a force in the axial direction. The force detection sensor unit includes a pair of ring-shaped sensor targets sandwiching both end surfaces of the outer ring of the rolling bearing, and a pair of leaf springs that support the sensor targets. And a gap sensor that detects a gap with respect to the sensor target, and the leaf spring has a main shaft diameter. Current sensor means for detecting the current flowing through the electromagnet, or leakage magnetic flux detection for detecting the amount of magnetic flux leaked from the electromagnet. A correction amount calculating means for calculating a correction amount according to the current value detected by the current detection means or the leakage magnetic flux detected by the leakage magnetic flux detection means, and a controller for controlling the electromagnet; Since the addition means for adding the correction amount calculated by the means to the output of the force detection sensor unit is provided, the long-term durability of the rolling bearing against the load of the thrust load can be improved, and the thermal expansion can be achieved with a simple and inexpensive configuration. The magnetic bearing can be accurately controlled without being affected by the unbalance of the magnet or the magnetic flux leakage of the electromagnet.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a cross-sectional view of a turbine unit 5 incorporating the 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 attached to both ends of the main shaft 13, respectively. It has been. Further, the compressor impeller 6a is driven by the power generated in the turbine impeller 7a, and no other drive source is provided.

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.

In the magnetic bearing device in the turbine unit 5, the main shaft 13 is supported by 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 supported by an electromagnet 17 that is a magnetic bearing. It is supposed to support. The turbine unit 5 includes a force detection sensor unit 18 that detects a thrust force acting on the main shaft 13 by air in the compressor 6 and the expansion turbine 7, and a supporting force by the electromagnet 17 according to the output of the force detection sensor unit 18. And a magnetic bearing controller 19 for controlling the motor.
A pair of electromagnets 17 is installed in the spindle housing 14 so as to face the both surfaces of a flange-like thrust plate 13a made of a ferromagnetic material provided in the center of the main shaft 13 in the non-contact manner.

  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 13b at the center and small-diameter portions 13c at both ends. The bearings 15 and 16 on both sides have their inner rings 15a and 16a fitted into the small diameter portion 13c in a press-fit state, and one of the width surfaces engages with a stepped surface between the large diameter portion 13b and the small diameter portion 13c.
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. The non-contact seals 21 and 22 are labyrinth seals in which a plurality of circumferential grooves are arranged in the axial direction on the inner diameter surface of the spindle housing 14.

The force detection sensor unit 18 is provided on the stationary side of the rolling bearing 16 on the turbine impeller 7a side. As shown in FIG. 2, the force detection sensor unit 18 includes a pair of ring-shaped sensor targets 31 and 32 sandwiching both end surfaces of the outer ring 16 b of the rolling bearing 16, and the sensor targets 31 and 32. And a gap sensor 35 provided on the bearing housing 14b of the spindle housing 14 so as to face each side of the sensor target 31, 32 facing the bearing. The spindle housing 14 includes the bearing housing 14b that is positioned around the rolling bearing 16 and supports the outer ring 16b of the rolling bearing 16, and a spindle housing body 14a that is coupled to the bearing housing 14b. The gap sensor 35 is a sensor that detects a gap with respect to the sensor targets 31 and 32. The outer ring 16b of the rolling bearing 16 is supported on the inner diameter surface of the bearing housing 14b so as to be movable in the axial direction.
The pair of leaf springs 33, 34 are attached to the spindle housing 14 (bearing housing 14 b) at the radially outer side portion of the main shaft 13, and the sensor targets 31, 34 are attached to the inner diameter side portions of the leaf springs 33, 34. 32 is attached. Thereby, a certain amount of movement stroke in the axial direction is given to each sensor target 31, 32 with respect to the outer ring 16 b of the rolling bearing 16. Therefore, when the outer ring 16b of the rolling bearing 16 is displaced in the axial direction by the thrust force acting on the main shaft 13, a gap between each side of the bearing housing 14b and each side of the sensor targets 31 and 32 facing the one side is generated. fluctuate. The pair of leaf springs 33 and 34 are arranged so as to sandwich the rolling bearing 16 in the axial direction, so that the moment disturbance resistance can be improved.

  In the force detection sensor unit 18 configured as described above, the gap between the gap sensor 35 and the sensor targets 31 and 32 that change according to the thrust force acting on the main shaft 13 is detected by the gap sensor 35, and the detected value is obtained. It is converted into a thrust force by the magnetic bearing controller 19. In this case, with respect to the thrust force in one direction, the gaps detected on the left and right in the axial direction across the rolling bearing 16 are opposite to each other. Each output of 35 and 35 is differentially calculated and converted into a thrust force. As described above, by performing the differential operation, the influence of the temperature drift of the gap sensors 35 and 35 generated in the detection result is reduced.

The gap sensor 35 is a magnetic gap sensor, and a ring-shaped groove 14ba is formed on each side of the bearing housing 14b facing the sensor targets 31 and 32 around the axis O of the main shaft 13, A ring-shaped coil 36 is inserted into the groove 14ba. In this case, the bearing housing 14 b also serves as a yoke portion that forms a magnetic path around the coil 36 in the gap sensor 35. By configuring in this way and enlarging the area of the magnetic path, sensor sensitivity can be improved. As a result, the accuracy of attaching the gap sensor 35 to the bearing housing 14b can be tightened, and the sensor sensitivity can be improved without using a high permeability material for the bearing housing 14b. The magnetic bearing can be accurately controlled without being affected by the balance.
Further, when the magnetic sensor having the above configuration is used as the gap sensor 35, if a resonance circuit or a phase detection circuit is used as a detection circuit for detecting a change in the inductance of the coil, the carrier frequency depends on the material of the bearing housing 14b. It is possible to improve the sensitivity by reducing.

  In the configuration of the support system for the sensor targets 31 and 32 in the force detection sensor unit 18, it is necessary to shorten the axial length as much as possible due to the problem of the natural frequency. For this reason, the support system needs to have a flat structure. In this embodiment, since the sensor targets 31 and 32 are supported by the leaf springs 33 and 34, a flat structure can be easily realized. For example, when a coil spring is used instead of the leaf springs 33 and 34, the flat structure is provided. It is difficult to realize. Moreover, when the leaf | plate springs 33 and 34 are used, various rigidity can be implement | achieved by adjusting the thickness and inner / outer diameter of a board | plate. A way washer or a Belleville spring can be used in place of the leaf springs 33 and 34, but in this case, it is difficult to reduce the spring rigidity because of the structure of the spring member.

  FIG. 4 shows another configuration example of the force detection sensor unit 18. In this configuration example, in the gap sensor 35 in FIG. 2, the groove width of each one-side ring-shaped groove 14ba in the bearing housing 14b is increased, and the coil 36 inserted into the groove 14ba has an inner diameter side and an outer diameter side. High magnetic permeability rings 37A and 37B are inserted to increase the area of the magnetic path around the coil 36, thereby improving sensitivity. The rings 37A and 37B may be only one of the inner diameter side and the outer diameter side. Other configurations are the same as those in the configuration of FIG.

In the magnetic bearing controller 19 of FIG. 5 shown in the block diagram, the sensor output arithmetic circuit 40 adds / subtracts the detection outputs P1, P2 of the gap sensors 35 in the force detection sensor unit 18. The magnetic bearing controller 19 is provided with a current detection circuit 41 that detects a current flowing through the electromagnet 17 and a correction amount calculation circuit 42 that calculates a correction amount according to the current value detected by the current detection circuit 41. . The leakage magnetic flux from the electromagnet 17 affects the detection outputs P1 and P2 of the gap sensor 35 disposed in the vicinity thereof as a drift. Therefore, the correction amount calculation circuit 42 calculates a correction amount corresponding to a drift caused as a result of the leakage magnetic flux in the detection outputs P1 and P2 of the gap sensor 35 from the current value of the electromagnet 17 detected by the current detection circuit 41. The detection outputs P1 and P2 of the gap sensor 35 and the correction amount calculated by the correction calculation circuit 42 are added by the adder 43, thereby canceling the drift generated in the detection outputs P1 and P2 of the gap sensor 35. As a result, the magnetic bearing can be accurately controlled without being affected by the leakage magnetic flux of the electromagnet 17.
The detection output corrected in this way is input to the PI compensation circuit (or P compensation circuit) 44. The pre-stage portion of the PI compensation circuit (or P compensation circuit) 44 is a comparator, which calculates the deviation by comparing the corrected detection output described above with a predetermined reference value. Further, the PI compensation circuit (or P compensation circuit) 44 computes a control signal for the electromagnet 17 by performing proportional integral (or proportional) processing that appropriately sets the calculated deviation according to the turbine unit 5. The output of the PI compensation circuit (or P compensation circuit) 44 is input to power circuits 47 and 48 that drive the electromagnets 171 and 172 in each direction via diodes 45 and 46, 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 attractive force acts. Therefore, the direction of current is determined in advance by the diodes 45 and 46, and the two electromagnets 171 and 172 are used. Is driven selectively. The current detection circuit 41 detects the current output from the power circuits 47 and 48.

  The turbine unit 5 having this configuration is applied to, for example, an air cycle refrigeration cooling system and compressed by a compressor 6 so that air as a cooling medium can be efficiently heat-exchanged by a subsequent heat exchanger (not shown here). Then, the temperature is increased, and the air cooled by the heat exchanger in the subsequent stage is cooled and discharged by the 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.

In this turbine unit 5, the compressor impeller 6a and the turbine impeller 7a are attached to a common main shaft 13, and the compressor impeller 6a is driven by the power generated in the turbine impeller 7a, so that no power source is required. Cooling can be efficiently performed with a compact configuration.
In order to secure 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. In the 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 pressure of air 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, a force detection sensor unit 18 that detects a thrust force acting on the main shaft 13 by the air in the compressor 6 and the expansion turbine 7, and the supporting force by the electromagnet 17 is controlled according to the output of the force detection sensor unit 18. Since the magnetic bearing controller 19 is provided, the rolling bearings 15 and 16 can be used in an optimum state with respect to the thrust force according to the bearing specifications.
Further, the force detection sensor unit 18 includes a pair of ring-shaped sensor targets 31 and 32 sandwiching both end surfaces of the outer ring 16b of the rolling bearing 16 and a pair of leaf springs 33 and 34 that support the sensor targets 31 and 32. And the gap sensor 35 for detecting the gap with respect to the sensor targets 31 and 32, the magnetic bearing can be accurately controlled without being affected by the imbalance of thermal expansion.
In particular, in the magnetic bearing controller 19, the current flowing through the electromagnet 17 is detected by the current detection circuit 41, and a correction amount corresponding to the current value detected by the current detection circuit 41 is calculated by the correction amount calculation circuit 42. The drift caused by the influence of the leakage magnetic flux of the electromagnet 17 is canceled by adding the corrected amount to the output of the force detection sensor unit 18 by the adder 43, so that the magnetism is not affected by the leakage magnetic flux of the electromagnet 17. The bearing can be accurately controlled.
Further, the gap sensor 35 is a gap sensor in which a ring-shaped groove 14ba centering on the spindle axis O is formed in the spindle housing 14 (bearing housing 14b), and a ring-shaped coil 36 is inserted into the groove 14ba. Since the yoke portion forming the magnetic path around the ring-shaped coil 36 is also used as the spindle housing 14 (bearing housing 14b), the sensitivity can be improved with a simple and inexpensive configuration.

  Therefore, 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. Since the long-term durability of the bearings 15 and 16 is improved, the reliability of the entire air cycle refrigeration cooling turbine unit 5 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.

  The bearings 15 and 16 are disposed in the vicinity of the compressor impeller 6a and in the vicinity of the turbine impeller 7a, and the main shaft 13 is supported at both ends, so that more stable high-speed rotation is possible.

  Since non-contact seals 21 and 22 are provided between the main shaft 13 and the spindle housing 14 on the end side of the bearings 15 and 16, air passes through the bearings 15 and 16 and the like with the compressor 6. Leakage between the expansion turbines 7 is prevented. Since there is a large pressure difference between the inside of the compressor 6 and the inside of the expansion turbine 7, the inside of each bearing 15, 16 and the surface on which the inner and outer rings 15 a, 16 a of each bearing 15, 16 are fitted to the main shaft 13 and the spindle housing 14 Air leaks are about to occur. Such air leakage causes the efficiency of the compressor 6 and the expansion turbine 7 to decrease, and the air passing through the bearings 15 and 16 contaminates the bearings 15 and 16 when there is dust, or lubricates the bearings. There is a risk that the material may be dried to reduce durability. Such a decrease in efficiency and the fouling of the bearings 15 and 16 are prevented by the non-contact seals 21 and 22.

  6 and 7 show another embodiment of the turbine unit 5. In this embodiment, as shown in FIG. 6, a magnetic flux detection sensor 49 that detects a leakage magnetic flux from the electromagnet 17 is provided in the vicinity of the force detection sensor unit 18, and correction according to the leakage magnetic flux detected by the magnetic flux detection sensor 49. The correction amount calculation circuit 42A for calculating the amount is provided, and the correction amount calculated by the correction amount calculation circuit 42A is added to the output of the sensor output calculation circuit 40 by the adder 43, whereby the output generated by the force detection sensor unit 18 is generated. The drift caused by the leakage magnetic flux is canceled. Other configurations are the same as those in the previous embodiment.

  Also in this embodiment, the drift generated in the output of the force detection sensor unit 18 due to the leakage magnetic flux of the electromagnet 17 can be canceled, so that the magnetic bearing can be accurately controlled without being affected by the leakage magnetic flux.

  FIG. 8 shows still another embodiment of the turbine unit 5. In the embodiment shown in FIG. 1, the turbine unit 5 is provided with a motor 25 that rotationally drives the main shaft 13. The motor 25 is provided side by side with the electromagnet 17 and includes a stator 26 provided on the spindle housing 14 and a rotor 27 provided on the main shaft 13. The stator 26 has a stator coil 26a, and the rotor 27 is made of a magnet or the like. The motor 25 is controlled by the motor controller 28 of FIG. 9 shown in the block diagram. That is, the motor controller 28 adjusts the phase of the motor drive current by the phase adjustment circuit 29 using the rotation angle of the motor rotor 28a as a feedback signal based on the rotation synchronization command signal, and the motor drive current corresponding to the adjustment result is supplied to the motor. By supplying the stator coil 26a from the drive circuit 30, constant rotation control is performed. The rotation synchronization command signal is calculated according to the output of a rotation angle detection sensor (not shown) provided on the rotor 27. Other configurations are the same as those of the embodiment shown in FIG.

  In the turbine unit 5, the compressor impeller 6 a is rotationally driven by the driving force of the turbine impeller 7 a generated in the expansion turbine 7 and the driving force of the motor 25. Therefore, the compressor 6 can be driven without the pre-compression means, and the system can be made compact.

FIG. 10 shows still another embodiment of the turbine unit 5. This turbine unit 5 is also provided with a motor 25 for rotationally driving the main shaft 13 in the embodiment shown in FIG.
The electromagnet 17 is in non-contact with each surface of the two flange-shaped thrust plates 13aa and 13ab made of a ferromagnetic material that is arranged 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 has a spindle housing that faces one surface of the thrust plate 13aa located near the expansion turbine toward the expansion turbine 7 as an electromagnet target in a non-contact manner. 14 is installed. The other electromagnet 17 constituting the magnetic bearing is installed on the spindle housing 14 so as to face the one surface of the thrust plate 13ab located near the compressor 6 toward the compressor 6 side, with the electromagnet target facing the one surface in a non-contact manner. The

  The motor 25 includes a rotor 27 provided on the main shaft 13 along with the electromagnet 17, and a stator 26 facing the rotor 27 in the axial direction. The rotor 27 includes a pair of left and right permanent magnets 27a arranged at equal pitches in the circumferential direction on each side of the main shaft 13 opposite to the side where the electromagnets 17 of the thrust plates 13aa and 13ab face each other. Is configured. Thus, between the permanent magnets 27a arranged opposite to each other in the axial direction, the magnetic poles are set to be different from each other.

  The stator 26 of the motor 25 includes a stator coil 26a arranged without a core so as to face each surface of both the rotors 27 in a non-contact manner at a central position in the axial direction between the pair of left and right rotors 27. It is configured by being installed in the spindle housing 14. The motor 25 rotates the main shaft 13 by Lorentz force acting between the rotor 27 and the stator 26. Thus, since this axial gap type motor 25 is a coreless motor, the negative rigidity due to the magnetic coupling between the rotor 27 and the stator 26 is zero.

  In the turbine unit 5, as cooling means for the motor 25, a motor part cooling air introduction path 50 for supplying cooling air into the motor 25 from the outside, and an exhaust path for exhausting the supplied air to the outside of the motor 25. 51 is provided in the spindle housing 14.

The motor part cooling air introduction path 50 introduces a part of the air flowing into the turbine impeller 7a into the motor 25, and between the suction port in the space in the turbine housing 7b and the turbine impeller 7a. The route entrance 52 is open. The path inlet 52 may be opened to the discharge port 7d in the turbine housing 7b. In this case, a part of the air discharged from the turbine impeller 7a is introduced into the motor 25.
The motor part cooling air introduction path 50 is branched into two branch paths 50A and 50B, and opens from the motor-side opening 53 serving as a path exit at the tip of each branch path 50A and 50B to the space around the rotor in the motor 25. ing. The two branch paths 50 </ b> A and 50 </ b> B pass through the yokes of the electromagnets 17 of the magnetic bearings on both sides, and the motor side opening 53 is located on the inner peripheral portion of the rotor 27.
The exhaust path 51 is opened from the outer diameter portion of the rotor 27 to the outer diameter surface of the spindle housing 14 in the space in the motor 25. Other configurations are substantially the same as those in the embodiment of FIG.

  In this embodiment, two electromagnets 17 are arranged on the axially outer side of the two thrust plates 13aa and 13ab provided on the main shaft 13 side by side in the axial direction to constitute a magnetic bearing, and both the thrust plates 13aa and 13ab are used. By arranging the axial gap type motor 25 at the sandwiched position, the magnetic bearing and the motor 25 have a compact integrated structure, so that the shaft length of the main shaft 13 can be shortened, and the natural frequency of the main shaft 13 is increased accordingly. The spindle 13 can be rotated at a high speed.

  In this embodiment, as a cooling means for the motor 25, a motor part cooling air introduction path 50 for supplying cooling air into the motor 25 from the outside, and an exhaust path for exhausting the supplied air to the outside of the motor. Since 51 is provided, the necessary motor cooling can be performed with a simple configuration in which the introduction path 50 and the exhaust path 51 are provided. In this case, since the motor part cooling air introduction path 50 uses inflow or discharge air into the turbine impeller 7a, the cooling air can be forcibly circulated without requiring a dedicated air supply source such as fans. With a simple configuration, efficient motor cooling can be performed.

  Since the motor 25 is an axial gap motor, the main shaft 13 can be configured to be short, and the main shaft 13 can be rotated at high speed without causing a resonance problem. However, it is difficult to efficiently cool the motor 25. However, since a part of the air flowing into the turbine impeller 7a or discharged from the turbine impeller 7a is introduced into the motor 25 as described above, an excellent cooling effect by forced circulation of the cooling air with a simple configuration. Is obtained. Further, in the axial gap motor, the rotor 27 becomes large in the radial direction, and the centrifugal force due to the rotation of the rotor 27 affects the air in the motor 25. Since it introduced from the inner diameter part of 27 and discharged | emitted from the outer diameter part, the efficient flow of cooling air is obtained and the more excellent cooling effect is obtained.

  FIG. 11 shows still another embodiment of the turbine unit 5. This turbine unit 5 is also provided with a motor 25 that rotationally drives the main shaft 13 as in the embodiment shown in FIG. In the embodiment shown in FIG. 10, 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 13 a 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 25 includes a rotor 27 provided on the main shaft 13 and a stator 26 facing the rotor 27 in the axial direction. A pair of left and right rotors 27 is configured by arranging permanent magnets 27a arranged at equal pitches in the circumferential direction on the outer diameter side of the thrust plate 13a on both sides of the thrust plate 13a. Thus, between the permanent magnets 27a 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 27a.
A pair of left and right stators 26 installed on the spindle housing 14 are configured so as to face the rotors 27 on both sides of the thrust plate 13a in a non-contact manner. The two left and right motors 25 configured to sandwich the thrust plate 13 a in this way rotate the main shaft 13 by the magnetic force acting between the rotor 27 and the stator 26. The motor part cooling air introduction path 50 is provided as one without branching. Other configurations are the same as those in the embodiment of FIG.

  FIG. 12 shows the overall configuration of an air cycle refrigeration cooling system using the turbine unit 5 of FIG. This air cycle refrigeration cooling system is a system that directly cools air in a space to be cooled 10 such as a freezer as a refrigerant, and an air circulation path from an air intake port 1a to a discharge port 1b respectively opened in the space to be cooled 10 1 In this air circulation path 1, pre-compression means 2, first heat exchanger 3, dehumidifier 4, compressor 6 of air cycle refrigeration cooling turbine unit 5, second heat exchanger 8, intermediate heat exchanger 9, And the expansion turbine 7 of the said turbine unit 5 is 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.

  This air cycle refrigeration cooling system is a system that keeps the space 10 to be cooled at about 0 ° C. to −60 ° C., from the space to be cooled 10 to the intake 1a of the air circulation path 1 at about 0 to −60 ° C. and 1 atm. Air flows in. Note that the numerical values of temperature and atmospheric pressure shown below are examples that serve as a rough standard. 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 dehumidifier 4 prevents the moisture in the air in the air circulation path 1 from freezing due to cooling below the freezing point in the subsequent stage and causing clogging of the air circulation path 1 and galling of the expansion turbine 7. Dehumidify the air.

The air at 40 ° C. and 1.4 atm after dehumidification is compressed to 1.8 atm by the compressor 6 of the turbine unit 5, and the second heat exchanger 8 is heated to about 70 ° C. by this compression. To 40 ° C. 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.

  FIG. 13 shows an overall configuration of an air cycle refrigeration cooling system using the turbine unit 5 of FIG. The configuration excluding the turbine unit 5 is substantially the same as that of the air cycle refrigeration cooling system of FIG. In this case, a part of the air of −20 ° C. input to the expansion turbine 7 is used for cooling the motor 25 and mixed with the input of the compressor 6. By this method, the motor 25 can be cooled by a simple method.

It is sectional drawing of the turbine unit in which the magnetic bearing apparatus concerning one Embodiment of this invention was integrated. It is sectional drawing which shows one structural example of the force detection sensor unit in the turbine unit. It is a front view which shows the arrangement configuration of the gap sensor in the same force detection sensor unit. It is sectional drawing which shows the other structural example of a force detection sensor unit. It is a block diagram which shows an example of the controller for magnetic bearings used for the magnetic bearing apparatus of FIG. It is sectional drawing of the turbine unit in which the magnetic bearing apparatus concerning other embodiment of this invention was integrated. It is a block diagram which shows an example of the controller for magnetic bearings used for the magnetic bearing apparatus. It is sectional drawing of the turbine unit in which the magnetic bearing apparatus concerning further another embodiment of this invention was integrated. It is a block diagram which shows an example of the controller for motors used for the magnetic bearing apparatus. It is sectional drawing of the turbine unit in which the magnetic bearing apparatus concerning further another embodiment of this invention was integrated. It is sectional drawing of the turbine unit in which the magnetic bearing apparatus concerning further another 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 a systematic diagram of the air cycle refrigeration cooling system to which the turbine unit of FIG. 10 is applied. It is sectional drawing of a proposal example. It is sectional drawing of the force detection sensor unit in the proposal example. It is a front view which shows the arrangement configuration of the gap sensor in the same force detection sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Precompression means 3 ... 1st heat exchanger 5 ... Turbine unit 6 ... Compressor 6a ... Compressor impeller 7 ... Expansion turbine 7a ... Turbine impeller 8 ... 2nd heat exchanger 13 ... Main shaft 13a, 13aa, 13ab ... Thrust plate 14 ... Spindle housing 14a ... Spindle housing body 14b ... Bearing housing 14ba ... Grooves 15, 16 ... Rolling bearing 17 ... Electromagnet 18 ... Force detection sensor unit 19 ... Magnetic bearing controller 25 ... Motor 26 ... Motor stator 27 ... Motor rotor 31, 32 ... Sensor targets 33, 34 ... Leaf spring 35 ... Gap sensor 36 ... Coil 41 ... Current detection circuit 42, 42A ... Correction amount calculation circuit 43 ... Adder 49 ... Magnetic flux detection sensor

Claims (5)

Rolling bearing and magnetic bearing are used together, the rolling bearing supports the radial load, the magnetic bearing supports the axial load and / or the bearing preload, and the electromagnet is a ferromagnetic body that is perpendicular and coaxial with the main shaft. Magnetic bearing having a controller that controls an electromagnet according to an output of a force detection sensor unit that is attached to a spindle housing so as to face a flange-shaped thrust plate made of A device,
The force detection sensor unit includes a pair of ring-shaped sensor targets sandwiching both end surfaces of an outer ring of a rolling bearing, a pair of leaf springs that support each of the sensor targets, and a gap sensor that detects a gap with respect to the sensor target. The leaf spring is attached to the spindle housing at the outer diameter side portion in the main shaft radial direction and the sensor target is attached to the inner diameter side portion.
A current detection means for detecting a current flowing through the electromagnet or a leakage flux detection means for detecting a leakage magnetic flux amount of the electromagnet is provided, and a current value detected by the current detection means or the leakage flux is provided in a controller for controlling the electromagnet. A correction amount calculation means for calculating a correction amount according to the leakage magnetic flux detected by the detection means, and an addition means for adding the correction amount calculated by the correction amount calculation means to the output of the force detection sensor unit. A magnetic bearing device.   2. The gap sensor according to claim 1, wherein the gap sensor is a magnetic gap sensor in which a ring-shaped groove centering on a rotor axis is formed in a spindle housing, and a ring-shaped coil is inserted into the groove. A magnetic bearing device in which the spindle housing also serves as a yoke portion that forms a magnetic path around the coil.   3. The compressor / expansion turbine system according to claim 1, wherein a compressor side impeller and a turbine side impeller are attached to the main shaft, and the compressor impeller is driven by power generated by the turbine impeller. Magnetic bearing device.   3. A motor-integrated magnetic bearing device in which the main shaft is provided with the thrust plate and a motor rotor, and a compressor-side impeller and a turbine-side impeller are attached to the main shaft. A magnetic bearing device applied to a compression / expansion turbine system in which a compressor side impeller is driven by one or both of power generated in a vehicle.   5. The compression / expansion turbine system to which the magnetic bearing device is applied according to claim 3, wherein the inflowing air is compressed by pre-compression means, cooled by a heat exchanger, adiabatic expansion of the turbine unit by the expansion turbine, A magnetic bearing device that is applied to an air cycle refrigeration cooling system that sequentially performs the above.

Images