JP2013050180A - Magnetic bearing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make force on an external force direction reverse side act to a rotor, while suppressing increase in the number of components and consumption current, in a magnetic bearing mechanism.SOLUTION: The magnetic bearing mechanism includes a rotor to which external force acts, a stator core having a tube part covering the outer circumferential surface of the rotor, a first end wall part formed in the external force direction of axial both sides of the tube part, and a second end wall part formed on the external force reverse side of the axial both sides of the tube part, and a permanent magnet fixed within the tube part of the stator core so as to generate both of attraction force in the external force direction which acts from the first end wall part to the rotor and attraction force to the external force direction reverse side which acts from the second end wall part to the rotor, wherein one or both of the stator core and the rotor is constituted so that attraction force to the external force reverse side caused by the permanent magnet is larger than attraction force in the external force direction caused by the permanent magnet.

Description

  The present invention relates to a magnetic bearing mechanism including a permanent magnet.

  Conventionally, it is known to use a magnetic bearing as a bearing of a drive shaft. For example, in FIG. 1 of Patent Document 1, a rotating member (drive shaft), a tab (rotor) disposed concentrically with the drive shaft, a C-shaped member (stator core) disposed so as to surround the rotor, An axial magnetic bearing (magnetic bearing mechanism) including a permanent magnet attached to the center of a stator core so that the inner N pole faces the outer peripheral surface of the rotor and a coil portion disposed in the stator core is disclosed. Yes. In this magnetic bearing mechanism, the drive shaft is supported in a non-contact state by appropriately adjusting the current flowing through the coil portion and adjusting the axial magnetic force acting on the rotor.

  In addition, as disclosed in FIG. 1 of Patent Document 1, the magnetic flux from the permanent magnet flows through the rotor and then branches to the one side portion and the other side portion of the stator core in the axial direction. Then join again with permanent magnets. As a result, a so-called bias magnetic flux is generated by the permanent magnet. By generating the bias magnetic flux in this way, it becomes easy to provide linearity between the current flowing through the coil portion and the magnetic force acting on the rotor, so that the magnetic force acting on the rotor can be easily controlled.

Japanese National Patent Publication No. 10-501326

  Incidentally, an external force directed to one side in the axial direction may act on the rotor connected to the drive shaft. In this case, it is necessary to apply a force opposite to the external force direction to the rotor so as to hold the rotor at a predetermined position in the axial direction.

  On the other hand, it is conceivable to increase the magnetic force in the direction opposite to the external force direction by increasing the current flowing through the coil portion, but this increases power consumption. It is also conceivable to arrange the permanent magnet different from the permanent magnet to attract the drive shaft to the opposite side of the external force direction. However, this increases the number of parts, which increases the cost of the magnetic bearing mechanism.

  This invention is made | formed in view of this point, The objective is to make the force of the external force direction reverse side act on a rotor, suppressing the increase in a number of parts and current consumption.

  One aspect of the present invention for solving the above problems is a rotor that is connected to a drive shaft and that acts as an external force toward one side in the axial direction when the drive shaft rotates, and a cylindrical portion that covers the outer peripheral surface of the rotor; A stator core having a first end wall portion formed in the external force direction on both axial sides of the cylindrical portion, and a second end wall portion formed on the opposite side in the external force direction on both axial sides of the cylindrical portion. A coil portion disposed on the stator core so as to cause an axial magnetic force to act on the rotor, a control portion for adjusting a current flowing through the coil portion, and the first end wall portion acting on the rotor. A permanent magnet fixed in the cylindrical portion of the stator core so as to generate both an attractive force in the external force direction and an attractive force in the direction opposite to the external force direction acting on the rotor from the second end wall portion. One of the stator core and the rotor Alternatively, both are generated by the permanent magnet, and the attractive force in the direction opposite to the external force direction acting on the rotor from the second end wall portion is generated by the permanent magnet and acts on the rotor from the first end wall portion. It is comprised so that it may become larger than the attraction | suction force to the said external force direction to do.

In this configuration, the axial position of the rotor is adjusted by the control unit. For example, when the rotor is displaced from the predetermined position to one side in the axial direction, the control unit controls the current of the coil unit to apply a magnetic force on the opposite side to the displacement direction to return the rotor to the predetermined position. As a result, the rotor is held in a non-contact state at a predetermined position in the stator. In this configuration, due to the permanent magnet, the first end wall portion and the rotor, and the second end wall portion and the rotor A bias magnetic flux is generated between the two, and the bias magnetic flux generates both an attractive force in the external force direction and an attractive force in the direction opposite to the external force direction. By generating the bias magnetic flux in this way, it becomes easy to provide linearity between the current flowing through the coil portion and the magnetic force acting on the rotor, so that the magnetic force acting on the rotor can be easily controlled.

  In this configuration, an external force directed to one side in the axial direction acts on the rotor when the drive shaft rotates. In order to hold the rotor in a non-contact state at a predetermined position in the stator, it is necessary to apply a force opposite to the direction of the external force to the rotor.

  On the other hand, in this configuration, one or both of the stator core and the rotor is generated by the permanent magnet, and the attractive force to the side opposite to the external force direction acting on the rotor from the second end wall portion is the permanent magnet. It is configured to be larger than the attractive force in the external force direction generated by the magnet and acting on the rotor from the first end wall portion. If it carries out like this, a rotor will be attracted | sucked to the said external force direction reverse side entirely by the said permanent magnet.

  According to the present invention, the rotor is attracted to the side opposite to the external force direction by the permanent magnet. In this case, since a small amount of current flows through the coil portion in order to generate a magnetic force in the direction opposite to the external force direction, power for flowing the current can be reduced. In addition, according to the present invention, a permanent magnet for generating a bias magnetic flux is used to attract the rotor to the side opposite to the external force direction. If it carries out like this, since a rotor can be attracted | sucked to an external force direction reverse side, without providing another member, the raise of the cost of a magnetic bearing mechanism can be suppressed.

  Moreover, according to the present invention, for example, the structure of the magnetic bearing mechanism can be reduced in weight as compared with a case where a suction force is applied to the end face of the drive shaft to attract the rotor to the opposite side in the external force direction.

  Specifically, if an attractive force by a permanent magnet is applied from the second end wall portion to the end surface of the drive shaft, the second end wall portion that is continuous with the cylindrical portion needs to be extended to the end portion side of the drive shaft. In addition, the weight of the magnetic bearing mechanism is increased. In particular, when the end of the drive shaft opposite to the impeller protrudes from the rotor, the second end wall must be extended to the end, so the weight of the magnetic bearing mechanism is significantly increased. Become. On the other hand, in the present invention, the magnetic bearing mechanism can be reduced in weight because of the structure in which the attractive force of the permanent magnet acts on the rotor from the second end wall portion.

FIG. 1 is a schematic diagram illustrating an overall configuration of a turbo compressor according to the first embodiment. 2 is a plan view showing only the thrust magnetic bearing mechanism with the drive shaft and the thrust disk omitted, as viewed from the direction A in FIG. FIG. 3 is a longitudinal sectional view of the thrust magnetic bearing mechanism. FIG. 4 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism in the first modification of the first embodiment. FIG. 5 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism according to the second modification of the first embodiment. FIG. 6 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism according to the second embodiment. FIG. 7 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism according to the third embodiment. FIG. 8 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism according to the first modification of the third embodiment. FIG. 9 is a view corresponding to FIG. 3 of the thrust magnetic bearing mechanism according to the fourth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

Embodiment 1 of the Invention
Embodiment 1 of the present invention is a turbo compressor (1) having a thrust magnetic bearing mechanism (20) as a magnetic bearing mechanism according to the present invention. The turbo compressor (1) is connected to a refrigerant circuit (not shown) that performs a refrigeration cycle operation by circulating the refrigerant, and compresses the refrigerant.

  As shown in FIG. 1, the turbo compressor (1) includes a casing (2), an electric motor (10) accommodated in the casing (2), and a drive shaft (13) rotated by the electric motor (10). ) And an impeller (8) coupled to the drive shaft (13). The turbo compressor (1) is a so-called horizontal turbo compressor arranged so that the drive shaft (13) is in the horizontal direction.

  The casing (2) is formed in a horizontally long cylindrical shape with both ends closed. The space in the casing (2) is partitioned by a wall portion (3) arranged at a predetermined distance from the left end portion of the casing (2) in FIG. The space on the left side of the wall portion (3) forms an impeller chamber (4) that houses the impeller (8), and the space on the right side of the wall portion (3) houses the electric motor (10). Form a space (5). A compression space (4a) communicating with the impeller chamber (4) is provided on the outer peripheral side of the impeller chamber (4).

  The casing (2) includes a suction pipe (6) for guiding the refrigerant from the refrigerant circuit into the impeller chamber (4), and a high-pressure refrigerant compressed in the impeller chamber (4) for returning to the refrigerant circuit. The discharge pipe (7) is connected.

  The electric motor (10) includes a substantially cylindrical stator (11) fixed to the inner peripheral wall of the casing (2), and a cylindrical rotor (12) inserted through the stator (11) through a predetermined gap. ). A drive shaft (13) is connected and fixed to the rotor (12) so that the axis is coaxial with the axis of the rotor (12). A plurality of motor-side permanent magnets (12a) are embedded in the rotor (12). The rotor (12) rotates in the stator (11) by rotating so that the motor-side permanent magnet (12a) is attracted to the rotating magnetic field generated in the stator (11).

  The impeller (8) is formed by a plurality of blades so that the outer shape becomes a substantially conical shape. The impeller (8) is housed in the impeller chamber (4) in a state of being fixed to one end of the drive shaft (13).

  The turbo compressor (1) includes two radial magnetic bearings (14, 14) as magnetic bearings in addition to a thrust magnetic bearing mechanism (20), which will be described in detail later. The radial magnetic bearing (14) is for supporting the drive shaft (13) in the radial direction. The radial magnetic bearing (14) is disposed on one end side and the other end side of the drive shaft (13), respectively, so as to support both end sides of the drive shaft (13). The radial magnetic bearing (14) is fixed in the casing (2) and configured to support the drive shaft (13) in a non-contact state when energized. The radial magnetic bearing (14) may be a homopolar radial bearing or a heteropolar radial bearing.

  The thrust magnetic bearing mechanism (20) is for supporting the drive shaft (13) in the thrust direction. The thrust magnetic bearing mechanism (20) is disposed on the opposite side (right side in FIG. 1) of the impeller (8) in the casing (2).

  As shown in FIGS. 1 to 3, the thrust magnetic bearing mechanism (20) includes a stator core (21) fixed in the casing (2), a permanent magnet (30) disposed in the stator core (21), and A coil portion (31) and a thrust disk (35) connected to the drive shaft (13) and disposed in the stator core (21) with a predetermined gap are provided.

  The thrust disk (35) is formed in a slightly flat cylindrical shape in the axial direction, and is opposite to the impeller (8) side of the drive shaft (13) so as to be coaxial with the drive shaft (13) (see FIG. 1 is fixed to the right end). The outer diameter of the thrust disk (35) is sufficiently larger than the outer diameter of the drive shaft (13). The thrust disk (35) is integrally formed of, for example, a material having high magnetic permeability.

  The stator core (21) is disposed in the casing (2) so as to cover the thrust disk (35) from the outside. The stator core (21) includes a cylindrical portion (22) formed in a cylindrical shape, a first end wall portion (23) disposed at an end portion on the impeller (8) side of the cylindrical portion (22), and the cylinder A second end wall portion (24) disposed at an end of the portion (22) opposite to the impeller (8). The cylinder portion (22), the first end wall portion (23), and the second end wall portion (24) are integrally formed of, for example, a steel material.

  The cylindrical portion (22) is disposed so as to cover the outer peripheral surface of the thrust disk (35) at a distance from the outer peripheral surface of the thrust disk (35). The cylindrical portion (22) is arranged so that the central axis is coaxial with the central axis of the thrust disk (35). The outer peripheral surface of the cylindrical part (22) is fixed inside the casing (2).

  The first end wall portion (23) is formed so as to extend radially inward from the end portion on the impeller (8) side of the cylindrical portion (22). In the present embodiment, the first end wall portion (23) has an outer peripheral surface that overlaps with the outer peripheral surface of the cylindrical portion (22) in the axial direction, and the inner peripheral surface is slightly larger in diameter than the outer peripheral surface of the thrust disk (35). It is formed in an annular shape located inward of the direction. Of the end face on the thrust disk (35) side of the first end wall portion (23), the part facing the end face of the thrust disk (35) constitutes a first facing surface (23a). A slight gap (first gap (G1)) is formed between the first facing surface (23a) and the thrust disk (35).

  The second end wall portion (24) is formed so as to extend radially inward from the end portion of the cylindrical portion (22) opposite to the impeller (8). In the present embodiment, the second end wall portion (24) has an outer peripheral surface that overlaps with an outer peripheral surface of the cylindrical portion (22) in the axial direction, and an inner peripheral surface is more radial than the outer peripheral surface of the thrust disk (35). It is formed in an annular shape located inward. Of the end face on the thrust disk (35) side of the second end wall portion (24), the part facing the end face of the thrust disk (35) constitutes a second facing surface (24a). A slight gap (second gap (G2)) is formed between the second facing surface (24a) and the thrust disk (35). The size of the second gap (G2) is substantially the same as the size of the first gap (G1).

  The inner peripheral surface of the second end wall portion (24) is located radially inward from the inner peripheral surface of the first end wall portion (23). Thereby, the area of a 2nd opposing surface (24a) becomes larger than the area of a 1st opposing surface (23a).

  The coil part (31) includes a first coil part (32) and a second coil part (33). Both the first coil portion (32) and the second coil portion (33) are formed by winding a coil wire in an annular shape. The first coil portion (32) is disposed on the first end wall portion (23) side of the inner peripheral surface of the cylindrical portion (22) so that the central axis is coaxial with the drive shaft (13), and the second coil The portion (33) is disposed on the second end wall (24) side of the inner peripheral surface of the cylindrical portion (22) so that the central axis is coaxial with the drive shaft (13).

During operation of the thrust magnetic bearing mechanism (20), a current having a magnitude of I _b + I _d flows through the first coil portion (32), and I _b −I _d flows through the second coil portion (33). A large current flows. Here, I _d is a control current that fluctuates according to the axial position of the thrust disk (35), and I _b is each coil portion (regardless of the axial position of the thrust disk (35)). 32, 33). The bias current _Ib is a DC current having a constant value. The value of the control current I _d is adjusted by a thrust bearing coil control section which details will be described later (40).

Bias current I _b flowing through the first coil portion (32) flows in a clockwise direction in FIG. 2, the bias current I _b flowing through the second coil portion (33) flows in a counterclockwise direction in FIG. Thus, the periphery of the coil portions (32, 33), the direction of the arrow in FIG. 3, flows a bias magnetic flux due to the bias current I _b. In the state that caused the bias flux, by adjusting the magnitude of the control current I _d flowing through the first coil portion (32) and the second coil portion (33), a control current I _d, thrust Linearity can be given to the magnetic force acting on the disk (35). Thereby, control of the magnetic force which acts on a thrust disk (35) can be performed easily.

Permanent magnets (30), the magnetic flux generated due to the permanent magnet (30) (bias flux) of a same direction as the bias magnetic flux generated due to the bias current I _b flowing through the coil portion (31) It is fixed to the cylindrical part of the stator core (21). Specifically, the permanent magnet (30) has a cylindrical portion (22) such that the S pole faces radially inward and faces the outer peripheral surface of the thrust disk (35), and the N pole faces radially outward. ) Is fixed to the axial central portion of the inner peripheral surface.

  The permanent magnet (30) is composed of a plurality of plate magnets formed in a plate shape having a predetermined length. These plate magnets are attached to the inner peripheral surface of the cylindrical portion so as to surround the outer peripheral surface of the thrust disk (35). A slight gap (third gap (G3)) is formed between the S pole side of the permanent magnet (30) and the thrust disk (35).

Bias magnetic flux in the thrust magnetic bearing mechanism (20) is composed of both the bias magnetic flux due to the bias current I _b flowing through the coil portion (31), a bias magnetic flux due to the permanent magnet (30). In this way, for example, as compared with the case where the permanent magnet (30) is omitted in the thrust magnetic bearing mechanism, it is possible to reduce the value of the bias current I _b flowing through the coil unit, power consumption is reduced.

  In addition, although illustration is abbreviate | omitted, the turbo compressor (1) is provided with the some touchdown bearing. The touch-down bearing is for supporting the drive shaft (13) when the radial magnetic bearing (14) and the thrust magnetic bearing mechanism (20) are not energized or cannot be controlled for some reason. As a result, when the drive shaft (13) or the like collides with the radial magnetic bearing (14) or the thrust magnetic bearing mechanism (20), the radial magnetic bearing (14) or the thrust magnetic bearing mechanism (20) is damaged. Can be prevented.

  The turbo compressor (1) includes a radial bearing coil controller (not shown) for adjusting a current flowing in a coil part (not shown) of the radial magnetic bearing (14), and a coil part of the thrust magnetic bearing mechanism (20). And a thrust bearing coil controller (40) as a controller for adjusting the current flowing through (31). The thrust bearing coil controller (40) constitutes a part of the thrust magnetic bearing mechanism (20).

The thrust bearing coil control section (40) is for controlling the current flowing through the coil section (31). Specifically, the thrust bearing coil control unit (40) controls the power supply device (not shown) so that a current having a magnitude of I _b + I _d flows through the first coil unit (32). The power supply device is controlled so that a current having a magnitude of I _b −I _d flows through (33).

−Operation of turbo compressor−
Before the electric motor (10) is driven, the radial bearing coil controller starts energizing the coil portion of the radial magnetic bearing (14), and the thrust bearing coil controller (40) is connected to the thrust magnetic bearing mechanism (20). Energization of the coil part (31) is started. Thereby, the drive shaft (13) is supported in a non-contact state in both the radial direction and the thrust direction.

During operation of the turbo compressor (1), if for some reason the drive shaft (13) is displaced in the thrust direction and the thrust disk (35) is displaced from the specified position, the thrust bearing coil controller (40) The current _Id is controlled to adjust the magnetic force generated due to the current flowing through the first coil portion (32) and the magnetic force generated due to the current flowing through the second coil portion (33).

Specifically, when the thrust disk (35) is displaced from the predetermined position to the first end wall (23) side (left side in FIG. 3), the magnetic force generated by the second coil part (33) is changed to the first coil part. The value of the control current _Id is controlled so as to be larger than the magnetic force generated by (32). Thus, the thrust disk (35) is sucked toward the second end wall (24) and returned to a predetermined position. In addition, when the thrust disk (35) is displaced from the predetermined position to the second end wall (24) side (right side in FIG. 3), the magnetic force generated by the first coil part (32) is changed to the second coil part (33). The value of the control current _Id is controlled so as to be larger than the magnetic force generated by. As a result, the thrust disk (35) is sucked toward the first end wall (23) and returned to the predetermined position. The thrust disk (35) is thus supported in a non-contact state in the stator core (21).

  When the rotor (12) is rotationally driven by the start of the electric motor (10), the impeller (8) rotates in the impeller chamber (4). Thereby, the refrigerant is sucked from the suction pipe (6), and the sucked refrigerant is sent to the compression space (4a) by the impeller (8) and compressed to a high pressure. The refrigerant thus compressed is discharged from the discharge pipe (7) and returned to the refrigerant circuit.

  When the impeller (8) is rotationally driven by the electric motor (10), the refrigerant compressed by the impeller (8) enters the back side of the impeller (8) (the space on the right side of the impeller (8) in FIG. 1). Thereby, the thrust F toward the suction pipe (6) in the axial direction acts on the impeller (8). As a result, a thrust F as an external force acts on the drive shaft (13) and a member connected to the drive shaft (13), for example, the thrust disk (35).

  In the thrust magnetic bearing mechanism (20), in order to support the thrust disk (35) in a non-contact state, a force having the same magnitude as the thrust F and opposite to the thrust F acts on the thrust disk (35). It is necessary to let In order to do this, for example, it is conceivable to control the current flowing through the coil portion (31) to apply a reverse magnetic force having the same magnitude as the thrust F to the thrust disk (35). However, in order to do this, a relatively large amount of current must be passed, which increases power consumption. In addition, it is conceivable to use a permanent magnet different from the permanent magnet (30) to attract the thrust disk (35) to the opposite side of the thrust direction, but this increases the number of parts and increases the thrust magnetic bearing mechanism. Cost will rise.

On the other hand, in the first embodiment, the thrust disk generates a force F _PM opposite to the thrust F generated by the rotation of the impeller (8) using the permanent magnet (30) for generating the bias magnetic flux. (35). Specifically, the area of the second facing surface (24a) of the second end wall (24) of the stator core (21) is made larger than the area of the first facing surface (23a) of the first end wall (23). It is getting bigger.

In this case, since the magnetic resistance of the second gap (G2) is smaller than the magnetic resistance of the first gap (G1), the magnetic flux flowing through the second gap is larger than the magnetic flux flowing through the first gap. Become. As a result, as shown in FIG. 3, the attractive force _FPM2 generated in the direction opposite to the thrust direction due to the permanent magnet (30) is attracted in the thrust direction generated due to the permanent magnet (30). Force F is greater than _PM1 . Then, due to the permanent magnet (30), the thrust force F _PM (= F _PM2− F _PM1 ) on the opposite side in the thrust direction acts on the entire thrust disk (35).

In this way exert a suction force F _PM to the thrust disc (35), the amount of control current I _d flowing through the coil portion (31) to exert a force of thrust F direction opposite to the thrust disk (35) , Can be less. If it does so, electric power required in a thrust magnetic bearing mechanism (20) will be reduced.

The attraction force _FPM is generated by a permanent magnet (30) used for generating a bias magnetic flux. Thereby, for example, since it is not necessary to use a permanent magnet different from the permanent magnet (30) in order to generate the attractive force, an increase in the number of parts can be suppressed.

-Effect of Embodiment 1-
As described above, in the turbo compressor according to the first embodiment, the attraction force F _PM2 in the thrust direction opposite that generated by the permanent magnet (30) is set to be larger than the suction force F _PM1 to thrust direction Yes. Specifically, the area of the second facing surface (24a) of the second end wall (24) is made larger than the area of the first facing surface (23a) of the first end wall (23). As a result, an attractive force F _PM (= F _PM2 −F _PM1 ) acting on the thrust direction reverse side acts on the entire thrust disk (35) due to the permanent magnet (30). In this way, because it requires even smaller suction force in the thrust direction opposite to be generated by the coil unit (31) can be reduced value of the control current I _d flowing through the coil portion (31). Accordingly, it is possible to reduce the electric power required for the thrust magnetic bearing mechanism (20).

Further, the attractive force _FPM2 in the direction opposite to the thrust direction is generated by a permanent magnet (30) for generating a bias magnetic flux. If it carries out like this, since it becomes unnecessary to use a new member in order to generate _| occur _| produce the attraction _| suction force _FPM2 to the said thrust direction, the increase in a number of parts can be suppressed.

In the first embodiment, the suction force _FPM is generated by configuring the second end wall portion (24) to extend radially inward. Thereby, the said attractive force _FPM can be generated with a comparatively easy structure, without changing the shape of the stator core used conventionally. Moreover, the area of each facing surface (23a, 24a) of each end wall (23, 24) can be easily adjusted by adjusting the length of each end wall (23, 24) extending inward in the radial direction. Therefore, the attraction force _FPM required in the thrust magnetic bearing mechanism (20) can be easily adjusted.

In the first embodiment, the second facing surface (24a) of the second end wall portion (24) faces the axial end surface of the thrust disk (35). Since the end surface of the thrust disk (35) has a larger area than, for example, the end surface of the drive shaft (13), the second opposed surface (24a) is opposed over a wide range of the end surface of the thrust disk (35). A relatively large suction force _FPM can be obtained.

<< Variation 1 of Embodiment 1 of the Invention >>
In the first modification, the shape of the first end wall portion (23) of the stator core (21) is different from that in the first embodiment. Specifically, as shown in FIG. 4, the first end wall portion (23) is located on the impeller (22) in the cylindrical portion (22) so as to be positioned radially outward from the outer peripheral surface of the thrust disk (35). It is formed to extend from the end on the 8) side to the impeller (8) side. In the first modification, the first end wall portion (23) has an outer peripheral surface that overlaps with the outer peripheral surface of the cylindrical portion (22) in the axial direction, and an inner peripheral surface is slightly more than the outer peripheral surface of the thrust disk (35). It is formed in an annular shape located radially outward.

When the first end wall portion (23) is formed as described above, the distance between the first end wall portion (23) and the thrust disk (35) becomes relatively long, so the first end wall portion (23). And the thrust disk (35) are relatively less likely to flow magnetic flux. On the other hand, since the area of the second opposing surface (24a) of the second end wall (24) is relatively large and the second gap (G2) is very small, the second end wall (24) and the thrust disk Magnetic flux flows relatively easily between (35). Accordingly, an attractive force F _PM (= F _PM2 −F _PM1 ) acting on the opposite side of the thrust direction acts on the entire thrust disk (35) due to the permanent magnet (30).

As described above, by generating the attraction force _FPM by the permanent magnet (30) for generating the bias magnetic flux, the power required in the thrust magnetic bearing mechanism (20) can be reduced as in the case of the first embodiment. In addition, an increase in the number of parts in the thrust magnetic bearing mechanism (20) can be suppressed.

Further, according to the first modification, the magnetic flux is less likely to flow between the first end wall (23) and the thrust disk (35) as compared with the case of the first embodiment, so that the thrust disk (35) It is easy to increase the suction force _FPM on the opposite side of the thrust direction acting as a whole. As a result, even if thrust F generated by the rotation of the impeller (8) is relatively large, it can be sufficiently reduced the amount of control current I _d flowing through the coil portion (31).

  According to the first modification, when the thrust disk (35) is disposed in the stator core (21), the thrust disk (35) can be inserted from the first end wall (23) side of the stator core (21). Therefore, the assembly of the thrust magnetic bearing mechanism (20) is facilitated.

<< Modification 2 of Embodiment 1 of the Invention >>
The second modification is different from the first embodiment in the shape of the second end wall (24) of the stator core (21). Specifically, as shown in FIG. 5, the second end wall portion (24) is formed in a disc shape whose outer peripheral surface overlaps with the outer peripheral surface of the cylindrical portion (22) when viewed in the axial direction.

Even with such a configuration, the attraction force _FPM can be generated by the permanent magnet (30) for generating the bias magnetic flux. Therefore, as in the case of the first embodiment, the power required in the thrust magnetic bearing mechanism (20) can be reduced, and an increase in the number of parts in the thrust magnetic bearing mechanism (20) can be suppressed.

Further, according to the second modification, the area of the second facing surface (24a) of the second end wall (24) can be increased as compared with the case of the first embodiment, and thus acts on the thrust disk (35). likely to increase the suction force F _PM in the thrust direction opposite. As a result, even if thrust F generated by the rotation of the impeller (8) is relatively large, it can be sufficiently reduced the amount of control current I _d flowing through the coil portion (31).

<< Embodiment 2 of the Invention >>
In the second embodiment of the present invention, the shape of the first end wall portion (23), the shape of the thrust disk (35), and the configuration of the thrust bearing coil control portion (40) are different from those of the first embodiment. Is different.

  In the second embodiment, the first end wall portion (23) is formed so that the inner peripheral surface thereof overlaps with the inner peripheral surface of the second end wall portion (24) when viewed in the axial direction. That is, in the second embodiment, the area of the first facing surface (23a) and the area of the second facing surface (24a) are the same.

  Further, as shown in FIG. 6, the axial length of the thrust disk (35) is shorter than that of the thrust disk (35) of the first embodiment.

In the second embodiment, the thrust bearing coil control unit (40) is configured such that when the drive shaft (13) rotates (when the thrust F acts on the thrust disk (35) by the rotation of the impeller (8)), The value of the control current _Id is adjusted so that the thrust disk (35) is held in the stator core (21) so that the two gaps (G2) are smaller than the first gap (G1).

Then, as in the case of the first embodiment, the attractive force _FPM2 generated in the direction opposite to the thrust direction due to the permanent magnet (30) is attracted in the thrust direction generated due to the permanent magnet (30). Since the force is greater than the force F _PM1 , an attractive force F _{PM in} the thrust direction reverse side acts on the entire thrust disk (35) due to the permanent magnet (30). Therefore, as in the case of the first embodiment, the power required for the thrust magnetic bearing mechanism (20) can be reduced, and an increase in the number of parts in the thrust magnetic bearing mechanism (20) can be suppressed.

Further, according to the second embodiment, the magnitude of the suction force F _PM that acts on the thrust disk (35) is adjusted according to the magnitude of the thrust of the impeller (8) that changes depending on the rotational speed of the impeller (8). It is also possible to do. Specifically, for example, when the rotational speed of the impeller (8) is low and the thrust F is small, and the suction force _FPM to the thrust disk (35) is to be reduced accordingly, the second gap (G2) size controls the control current I _d to be slightly larger than the size of the first gap (G1) by adjusting the axial position of the thrust disk (35), the suction force F _PM Can be small.

Further, for example, even if the direction of the thrust F may be opposite to that described above, the thrust bearing coil control unit (40) causes the size of the first gap (G1) when the drive shaft (13) rotates. There by adjusting the axial position of the thrust disk by controlling the control current I _d to be smaller than the size of the second gap (G2) (35), the thrust of the case described above and opposite occurs It is possible to deal with cases.

<< Embodiment 3 of the Invention >>
In Embodiment 3 of the present invention, the first end wall portion (23) and the second end wall portion (24) are made of materials having different magnetic permeability.

  In the third embodiment, as in the case of the second embodiment, the first end wall (23) has an inner peripheral surface that overlaps with an inner peripheral surface of the second end wall (24) in the axial direction view. Is formed. That is, in the second embodiment, the area of the first facing surface (23a) and the area of the second facing surface (24a) are the same.

And in this Embodiment 3, as shown in FIG. 7, a 2nd end wall part (24) has a magnetic permeability higher than the material (magnetic permeability (mu) ₁ ) which comprises a 1st end wall part (23). It is made of a material (permeability μ ₂ ).

In this case, since the magnetic flux flows more easily in the second end wall portion (24) than in the first end wall portion (23), the entire thrust disk (35) is caused by the permanent magnet (30). A suction force _{FPM in the} reverse direction of the thrust acts. Therefore, as in the case of the first and second embodiments, the power required for the thrust magnetic bearing mechanism (20) can be reduced, and an increase in the number of parts in the thrust magnetic bearing mechanism (20) can be suppressed.

In the third embodiment, all of the first end wall portion (23) is made of a material having a lower magnetic permeability than the material constituting the second end wall portion (24), but this is not restrictive. More specifically, each of the different sites in the stator core (21), by using a material of different permeability from each other, the attraction force F _PM2 in the thrust direction opposite side, than the suction force F _PM1 to thrust direction Any configuration can be used as long as it is large. For example, as shown in FIG. 8, only the portion of the first end wall portion (23) facing the thrust disk (35) is made to be more than the material (magnetic permeability μ ₂ ) constituting the other portion of the stator core (21). You may comprise with the material (magnetic permeability (micro | micron | mu) ₁ ) with low magnetic permeability (modification 1 of Embodiment 3).
<< Embodiment 4 of the Invention >>
The fourth embodiment of the present invention differs from the first embodiment in the configuration of the first end wall portion (23) and the configuration of the thrust disk (35).

  In the fourth embodiment, as in the second and third embodiments, the first end wall portion (23) has an inner peripheral surface that overlaps with the inner peripheral surface of the second end wall portion (24) when viewed in the axial direction. It is formed as follows. That is, in the second embodiment, the area of the first facing surface (23a) and the area of the second facing surface (24a) are the same.

And in this Embodiment 4, as shown in FIG. 9, the site | part by the side of a 2nd end wall part (24) among axial direction both sides of a thrust disk (35) is out of axial direction both sides of a thrust disk (35). It is made of a material (μ ₄ ) having a higher magnetic permeability than the magnetic permeability (μ ₃ ) of the material constituting the portion on the first end wall (23) side.

In this way, the magnetic flux flows more easily in the portion on the second end wall portion (24) side of the thrust disc (35) than in the portion on the first end wall portion (23) side of the thrust disc (35). the entire thrust disk (35), due to the permanent magnet (30), the suction force F _PM in the thrust direction opposite to the action. Therefore, as in the case of the first to third embodiments, the power required in the thrust magnetic bearing mechanism (20) can be reduced, and an increase in the number of parts in the thrust magnetic bearing mechanism (20) can be suppressed.

-Other embodiments-
About the said embodiment, you may make it the following structures.

In the above embodiment, the bias flux, and the bias magnetic flux due to the bias current I _b flowing through the coil portion (31), but is constituted by the bias magnetic flux due to the permanent magnet (30), but this shall, For example, by using a permanent magnet having a relatively large magnetic force, the bias magnetic flux may be formed only by the permanent magnet. In this case, since it is not necessary to flow the bias current _Ib through the coil section (31), the power consumption can be reduced accordingly.

  Further, in each of the above embodiments, a so-called horizontal turbo compressor is targeted, but the present invention is not limited to this, and a vertical turbo compressor can also be targeted. Moreover, not only a turbocompressor but any apparatus provided with a thrust magnetic bearing mechanism can be targeted.

  In each of the above embodiments, the turbo compressor in which the impeller (8) is coupled to one end of the drive shaft (13) is targeted. However, the present invention is not limited thereto, and the impeller is disposed at each of both ends of the drive shaft (13). A linked turbo compressor can also be targeted. In this case, the external force acting on the thrust disk is a resultant force of the thrust generated by each impeller.

  In each of the above embodiments, only the thrust of the impeller (8) is targeted as the external force F acting on the thrust disk (35). However, the present invention is not limited to this. For example, in the case of a vertical turbo compressor In this case, the resultant force of the impeller thrust and the gravity acting on the thrust disk becomes the target of the external force F.

In addition, the above embodiments and modifications can be combined as appropriate. For example, a combination of the first embodiment and the third embodiment (in the first embodiment, the second end wall portion is made of a material having higher magnetic permeability than the material constituting the first end wall portion) Combination of Embodiment 2 and Embodiment 4 (In Embodiment 2, the material on the second end wall portion side of the thrust disk has a higher magnetic permeability than the material constituting the portion on the first end wall portion side of the thrust disk. And the like. Thus, since the attraction force F _PM can be further increased, further the control current I _d flowing through the coil portion (31) can be reduced, thereby further reducing the power required in the thrust magnetic bearing mechanism (20).

  In each of the above embodiments, the magnetic bearing mechanism (20) has the thrust disk (35) disposed at the end of the drive shaft (13), and the end of the drive shaft (13) opposite to the impeller (8) side. The portion does not protrude from the thrust disk (35), but is not limited to this, and the end may protrude from the thrust disk (35).

  As described above, the present invention is particularly useful for a turbo compressor provided with a magnetic bearing mechanism.

DESCRIPTION OF SYMBOLS 1 Turbo compressor 13 Drive shaft 21 Stator core 22 Tube part 23 1st end wall part 24 2nd end wall part 30 Permanent magnet 31 Coil part 35 Thrust disk (rotor)
40 Thrust bearing coil control unit (control unit)
F Thrust (external force)
G1 first gap G2 second gap μ ₁ , μ ₂ , μ ₃ , μ ₄ permeability

Claims (6)

A rotor connected to the drive shaft and acting by an external force directed to one side in the axial direction when the drive shaft rotates;
A cylindrical portion covering the outer peripheral surface of the rotor, a first end wall portion formed in the external force direction on both axial sides of the cylindrical portion, and formed on the opposite side in the external force direction on both axial sides of the cylindrical portion A stator core having a second end wall portion,
A coil portion disposed on the stator core so as to cause an axial magnetic force to act on the rotor;
A control unit for adjusting a current flowing through the coil unit;
To generate both the suction force in the direction of the external force acting on the rotor from the first end wall portion and the suction force in the direction opposite to the external force direction acting on the rotor from the second end wall portion, A permanent magnet fixed in the cylindrical portion of the stator core,
One or both of the stator core and the rotor are generated by the permanent magnet, and the first end wall is generated by the permanent magnet, and the attraction force from the second end wall portion to the opposite side of the external force direction acting on the rotor is generated by the permanent magnet. A magnetic bearing mechanism, wherein the magnetic bearing mechanism is configured to be larger than the attractive force in the external force direction acting on the rotor from a portion. In claim 1,
The first end wall portion extends radially inward so as to face the one axial end surface of the rotor,
The second end wall portion extends radially inward so as to face the other axial end surface of the rotor,
The magnetic bearing mechanism, wherein an area of the second end wall portion facing the rotor is larger than an area of the first end wall portion facing the rotor. In claim 1,
The first end wall portion extends radially inward so as to face the one axial end surface of the rotor,
The second end wall portion extends radially inward so as to face the other axial end surface of the rotor,
In the control unit, when the drive shaft rotates, a second gap between the second end wall portion and the rotor is smaller than a first gap between the first end wall portion and the rotor. Thus, the magnetic bearing mechanism characterized by adjusting the current of the coil section. In claim 1,
The first end wall portion extends continuously in the axial direction from one axial end side of the cylindrical portion so as to be positioned radially outward from the outer peripheral surface of the rotor, and the second end wall portion is A magnetic bearing mechanism that extends radially inward so as to face the other axial end surface of the rotor. In any one of claims 1 to 4,
The magnetic bearing mechanism, wherein the magnetic permeability of the second end wall portion is larger than the magnetic permeability of the first end wall portion. In any one of claims 1 to 5,
A magnetic bearing characterized in that a magnetic permeability of a portion on the second end wall portion side of both sides in the axial direction of the rotor is larger than a magnetic permeability of a portion on the first end wall portion side of both sides in the axial direction of the rotor. mechanism.

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