JP4200776B2 - Magnetic bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing device in which a rotating body (for example, a rotary shaft of a flywheel) is magnetically levitated by non-contact support in an axial direction and a radial direction with a plurality of sets of magnetic bearings in an electric power storage device or the like.
[0002]
[Prior art]
The power storage device that stores power by rotating the flywheel requires a standby time of several hours or more, and is described in Patent Document 1 as a support mechanism, not a rolling bearing, in order to reduce bearing loss. A 5-axis control type magnetic bearing device is used.
[0003]
This five-axis control type magnetic bearing device includes a set of axial magnetic bearings that support a rotating body in a non-contact manner in the axial control axis direction, and non-rotating bodies in two radial control axis directions orthogonal to each other at two locations in the axial direction. Two sets of radial magnetic bearings for contact and support are provided. In the case of a magnetic bearing device in which a rotating body is arranged in the vertical direction, the weight of the rotating body is supported by controlling an electromagnet of an axial magnetic bearing.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 1-126423
[Problems to be solved by the invention]
In the above conventional magnetic bearing device, the rotating body is supported by its own weight by controlling the electromagnet of the axial magnetic bearing. Therefore, it is necessary to always supply a control current for supporting the own weight. The power consumption (copper loss) of the magnetic bearing is increased, and the loss of the flywheel power storage device is increased, which is an obstacle to improving the energy storage efficiency.
[0006]
An object of the present invention is to provide a magnetic bearing device that can reduce the power consumption of an axial magnetic bearing, and thus can improve the energy storage efficiency when used in a flywheel power storage device or the like. There is.
[0007]
[Means for Solving the Problems and Effects of the Invention]
A magnetic bearing device according to the present invention includes a rotating body, a plurality of sets of magnetic bearings that support the rotating body in a non-contact manner in the axial direction and the radial direction, an axial sensor unit for detecting the position of the rotating body in the axial direction, In a magnetic bearing device comprising a radial sensor unit for detecting the position of the body in the radial direction , a permanent magnet that attracts and suspends an axial disk portion provided on the rotating body in the axial direction, and a permanent magnet attraction An attraction force adjusting means for adjusting the force, the attraction force adjusting means facing the fixing member fixed to the magnet support that supports the permanent magnet, and the magnet support via the attraction force adjusting gap. Bei Eteori a moving body, the fixing member has an annular screw member male screw portion is formed on the outer periphery, the mobile internal thread portion on the inner circumference of form In addition, each screw member has a larger diameter than the outer diameter of the axial disk portion, and the screw members are screwed together so that they can move relative to each other, thereby fixing the moving body. It is configured to be movable with respect to the member, and the force for attracting the rotating body of the permanent magnet is adjusted by changing the size of the attraction force adjustment gap by the movement of the moving body. is there.
[0008]
The permanent magnet is preferably provided adjacent to the electromagnet of the axial magnetic bearing and supported by the electromagnet core. In this way, it is possible to reduce the size, and the axial magnetic bearing having the electromagnet and the permanent magnet can be handled as one unit, so that it can be easily used in place of the axial magnetic bearing having only the electromagnet.
[0009]
According to the magnetic bearing device of the present invention, the axial direction and radial direction of the rotating body are controlled by supplying a control current to the electromagnet of each magnetic bearing. At this time, the rotating body is attracted in the axial direction and suspended. Since the permanent magnet to be lowered is adjusted and the force for attracting the rotating body of the permanent magnet is adjusted, the control current for supporting the weight of the rotating body can be reduced. Therefore, the power consumption of the axial magnetic bearing is reduced. (Copper loss) decreases. For example, the attractive force of the permanent magnet preferably has an attractive force corresponding to the weight of the rotating body (not only the rotating shaft but also the weight of the entire unit that rotates together with the rotating shaft). Further, the moving body is moved to adjust the suction force adjustment gap. In this way, the control current for supporting the dead weight of the rotating body can be made substantially zero.
[0010]
Various configurations for moving the moving body are possible. For example, the moving body is preferably screwed so as to be relatively movable with a fixed member provided integrally with the magnet support. . In this way, it is possible to adjust the suction force by a simple operation of rotating the moving body clockwise or counterclockwise with respect to the fixed member, and it is easy to adjust the amount of movement because of the screw mechanism. Fine adjustment for optimization can be performed easily and accurately.
[0011]
Each of the fixed member and the moving body includes a screw member in which a screw portion is formed and a support member that supports the screw member. The support member is made of a material having better magnetic characteristics than the screw member. It is preferable that the material is stronger than the support member.
[0012]
The support member is disposed on the side close to the permanent magnet and used as a magnetic body that forms a magnetic circuit together with the permanent magnet. Therefore, by making this a material with good magnetic properties (for example, SS400), the maximum attractive force of the permanent magnet can be increased, and the adjustable range of the attractive force can be widened. Since a material having good magnetic properties is used for an electromagnet core or the like, the support member and the electromagnet core can be integrally formed of the same material. On the other hand, a material with good magnetic properties has relatively low strength and hardness , and when this is used as a screw member, it is slightly disadvantageous in terms of durability because a large attractive force is continuously applied. The durability of the screw member can be ensured by using a high-strength and high-hardness material such as SUS440C.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a flywheel power storage device will be described with reference to the drawings.
[0014]
As shown in FIG. 1, the flywheel power storage device is a non-contact type of a carbon fiber cylindrical flywheel (2) housed in a container (1) and a rotating shaft (3) of the flywheel (2). And a magnetic bearing device (4) to be supported.
[0015]
The magnetic bearing device (4) is a vertical type in which a vertical shaft-shaped rotating body (in this case, the rotating shaft of a flywheel) (3) rotates inside a substantially cylindrical casing (5) arranged vertically. It is. In the following description, the control axis in the axial direction (vertical direction) is the Z axis, and the two control directions in the radial direction (horizontal direction) orthogonal to the Z axis and orthogonal to each other are the X axis and the Y axis, respectively. To do.
[0016]
In the casing (5) of the magnetic bearing device (4), there are a control type axial magnetic bearing (6) for supporting the flywheel rotating shaft (3) in a non-contact manner in the Z-axis direction, and an upper and lower two of the flywheel rotating shaft (3). Two sets of upper and lower control type radial magnetic bearings (7) and (8) that support the position in the non-contact X-axis and Y-axis directions, and an axial sensor unit for detecting the axial position of the flywheel rotating shaft (3) ( 9) Two sets of upper and lower radial sensor units (10) (11) and flywheel (2) for detecting positions in the X and Y axis directions at the upper and lower positions of the flywheel rotating shaft (3) A cylindrical rotor (12) having a top wall integral with the peripheral wall and the flywheel rotating shaft (3), a stator unit (13) of a motor that rotates the rotor (12) at a high speed, and a rotational speed of the flywheel rotating shaft (3) Rotation sensor (14) and flywheel rotation axis ( 3) When the flywheel rotating shaft (3) cannot be supported in a non-contact manner by the magnetic bearings (6) (7) (8) by limiting the axial and radial displacement of 3), the flywheel rotating shaft (3) Two sets of upper and lower touchdown bearings (15) and (16) are provided to mechanically support the motor.
[0017]
The flywheel (2), the rotating shaft (3) of the flywheel (2) and the rotor (12) are the main components on the rotating side, and in the following, the configuration including all of these is the flywheel unit (2) (3) (12)
[0018]
The axial magnetic bearing (6) is an axial electromagnet coil (17) disposed so as to face the flange portion, that is, the axial disk portion (3a) provided at the lower end portion of the flywheel rotating shaft (3) from above in the Z-axis direction. And a permanent magnet (18) arranged adjacent to the outside in the radial direction thereof, and an electromagnet core (19) that also serves as a magnet support for supporting the electromagnet coil (17) and the permanent magnet (18). . The electromagnet core (19) constitutes the lower end portion of the casing of the magnetic bearing device (4). However, while the electromagnet core (19) is made of a ferromagnetic material, the main part of the casing indicated by reference numeral (5) is made of a nonmagnetic material (aluminum or the like). This prevents magnetic flux from flowing to members other than the electromagnet core (19), and makes it easy to calculate the magnetic circuit (magnetic force). The permanent magnet (18) is for supporting the weight of the flywheel unit (2) (3) (12), and the force that attracts the flywheel rotation shaft (3) of the permanent magnet (18) It is adjusted by the adjusting means (20).
[0019]
The attraction force adjusting means (20) is provided integrally with the electromagnet core (19), and thus is attached to the ring-shaped fixing member (31) of the same material as the electromagnet core (19), movably attached to the fixing member (31), and The electromagnet core (19) includes an annular moving body (32) that is opposed to the electromagnetic iron core (19) via the attractive force adjustment gap (G) .As will be described later, the size of the attractive force adjustment gap (G) is the moving body ( The force by which the permanent magnet (18) attracts the flywheel rotating shaft (3) is adjusted by being changed by the movement of 32).
[0020]
Each radial magnetic bearing (7) (8) has a pair of radial electromagnets (7a) (8a) arranged so as to sandwich the flywheel rotating shaft (3) from both sides in the X-axis direction, and the flywheel rotating And a pair of radial electromagnets (not shown) arranged so as to sandwich the shaft (3) from both sides in the Y-axis direction.
[0021]
The upper radial sensor unit (10) is for detecting the position of the flywheel rotating shaft (3) in the X-axis and Y-axis directions in the vicinity of the upper radial magnetic bearing (7). A pair of X-axis radial sensors (10a) arranged so as to sandwich the target portion (21) provided on the outer periphery of the flywheel rotating shaft (3) near the upper side of the X-axis direction, and the target It is composed of a pair of radial sensors for Y axis (not shown) arranged so as to sandwich the portion (21) from both sides in the Y axis direction. The lower radial sensor unit (11) is for detecting the position of the flywheel rotating shaft (3) in the X-axis and Y-axis directions in the vicinity of the lower radial magnetic bearing (8). A pair of X-axis radial sensors (11a) arranged so as to sandwich the target portion (22) provided on the outer periphery of the flywheel rotating shaft (3) near the lower side from both sides in the X-axis direction; It is composed of a pair of radial sensors for Y axis (not shown) arranged so as to sandwich the target portion (22) from both sides in the Y axis direction. Each of the radial sensors (10a) and (11a) is a known sensor, and outputs a signal corresponding to the size of the radial gap between the flywheel rotating shaft (3) and the target portions (21) and (22). Therefore, the position of the flywheel rotating shaft (3) in the X-axis direction is detected by each pair of X-axis radial sensors (10a) (11a), and the Y-axis of the rotating body is detected by each pair of Y-axis radial sensors. A position in the direction is detected. Each target part (21) (22) is constituted by laminating annular thin plates made of non-oriented silicon steel plates.
[0022]
A short cylindrical axial target (23) is concentrically attached to the lower end of the flywheel rotating shaft (3). The axial sensor unit (9) is for detecting the position of the flywheel rotating shaft (3) in the Z-axis direction, and faces the center of the lower end surface of the target (23) from below in the Z-axis direction. The axial sensor (9a) is arranged as described above. The axial sensor (9a) has a coil wound around a core. The rotation sensor (14) has the same characteristics as the axial sensor (9a). One or a plurality of detected parts (24) are formed on one circumference of the outer peripheral part of the lower end surface of the target (23). In this example, the detected portion (24) is formed by forming a recess in the outermost periphery of the lower end surface of the target (23). When a plurality of detected parts (24) are formed, they are provided at equal intervals in the circumferential direction. The axial sensor (9a) is a well-known sensor and outputs a signal corresponding to the position of the target (23) of the flywheel rotating shaft (3) in the Z-axis direction. Therefore, the position of the flywheel rotating shaft (3) in the Z-axis direction is detected by the axial sensor (9a).
[0023]
The upper touchdown bearing (15) limits the radial displacement of the flywheel rotating shaft (3). The outer ring (15a) of the upper touchdown bearing (15) is fixed to the casing (5), and the inner ring (15b) is not connected to the flywheel rotating shaft (3) by the magnetic bearings (6) (7) (8). In a state of contact and support, the shaft (3b) of the flywheel rotating shaft (3) is opposed to the shaft portion (3b) having a uniform outer diameter with a slight gap in the radial direction. The lower touchdown bearing (16) limits the displacement of the flywheel rotating shaft (3) in the axial direction and the radial direction. The outer ring (16a) of the lower touchdown bearing (16) is fixed to the electromagnetic iron core (19), and the inner ring (16b) is connected to the flywheel rotating shaft (3) by the magnetic bearings (6), (7), (8). In a non-contact supported state, the annular groove (25) formed on the outer periphery of the lower portion of the flywheel rotating shaft (3) faces the axial groove and the radial direction with a slight gap therebetween. In a state where the flywheel rotating shaft (3) is supported in a non-contact manner by the magnetic bearings (6) (7) (8), the inner ring (15b) of the upper touchdown bearing (15) and the flywheel rotating shaft (3) The radial clearance and the axial and radial clearance between the inner ring (16b) of the lower touchdown bearing (16) and the flywheel rotating shaft (3) are actually very small. Exaggerated.
[0024]
As shown in detail in FIG. 2, the electromagnet core (19) is formed in a double cylinder shape having an inner wall (19a), an outer wall (19b), and a top wall (19c). The lower end of the outer wall (19b) of the electromagnetic core (19) is positioned below the lower end of the inner wall (19a), and the flange (19d) provided at the lower end of the outer wall (19b) is a container (1). It is fixed to the bottom wall part. The electromagnet coil (17) is formed in an annular shape in contact with the inner wall (19a) and the top wall (19c), and the permanent magnet (18) is disposed on the radially outer side of the electromagnet coil (17) with a slight gap therebetween. It is formed in an annular shape in contact with the top wall (19c).
[0025]
The fixing member (31) of the suction force adjusting means (20) includes an annular screw member (33) having a screw portion (33a) formed on the outer periphery, and a bolt (35) disposed above the screw member (33). ) And an annular support member (34) coupled to the member (33). The support member (34) includes a perforated disk portion (34a) applied to the permanent magnet (18) from below and a cylindrical portion (34b) extending downward from the outer periphery thereof. The inner peripheral edge portion of the perforated disk portion (34a) is opposed to the outer peripheral edge portion of the axial disk portion (3a) of the flywheel rotating shaft (3) from directly above in the axial direction. A vertical female screw portion into which a bolt (35) penetrating the screw member (33) is screwed is formed at a required portion of the lower end portion of the cylindrical portion (34b). On the inner periphery of the screw member (33), a rising portion (33b) fitted to the inner periphery of the support member (34) is provided. A non-magnetic material (36) is interposed between the outer periphery of the permanent magnet (18) and the outer periphery of the upper portion of the support member (34) and the outer wall (19b) of the electromagnet core (19). The non-magnetic body (36) has an outer periphery that is in contact with the outer wall (19b) of the electromagnet core (19), and the outer periphery of the permanent magnet (18) is fitted into the inner periphery without any gaps. An annular recess is formed. Thus, the centering of the permanent magnet (18) and the electromagnet core (19) is performed using the non-magnetic material (36).
[0026]
The movable body (32) includes an annular screw member (37) having a female thread portion (37a) formed on the inner periphery thereof, and the member (37) disposed above the screw member (37) by a bolt (39). And an annular support member (38) coupled to the. Then, the screw member (37) of the moving body (32) and the screw member (33) of the fixing member (31) are screwed together so that they can move relative to each other, whereby the moving body (32) is fixed to the fixing member ( It is possible to move with respect to 31). The diameter of each screw member (33) (37) is larger than the outer diameter of the axial disk portion (3a) . With the moving body (32) screwed to the fixed member (31), there is a gap between the upper surface of the moving body (32) and the lower surface of the electromagnet core (19). It is considered as a gap (G). Further, the inner diameter of the upper part of the support member (38) of the movable body (32) and the outer diameter of the lower end part of the support member (34) of the fixed member (31) are set to be substantially the same size so that they can slide with each other. Yes.
[0027]
The fixed member (31) and the support members (34) and (38) of the moving body (32) are made of the same material as the electromagnet core (19), for example, a material having good magnetic properties such as SS400. ) And the moving member (32), the screw members (33) and (37) are inferior in magnetic properties to the support members (34) and (38), but a high-strength and high-hardness material such as SUS440C is used. in use. The support members (34) and (38) and the screw members (33) and (37) may be joined by other methods such as press-fitting, for example, without using the bolts (35) and (39).
[0028]
Since the attractive force adjusting means (20) is configured as described above, the permanent magnet (18) is connected to the axial disk of the flywheel rotating shaft (3) via the support member (34) of the fixed member (31). (3a), and this attractive force starts from the permanent magnet (18), the top wall (19c) of the electromagnetic iron core (19), the outer wall (19b), the attractive force adjustment gap (G), It varies depending on the characteristics of the magnetic circuit that returns to the permanent magnet (18) through the support member (38) of the movable body (32) and the support member (34) of the fixed member (31). That is, if the suction force adjustment gap (G) is increased, the force for sucking the flywheel rotating shaft (3) is increased, and if the suction force adjusting gap (G) is decreased, the flywheel rotating shaft (3) is sucked. The power to do is reduced. Therefore, the suction force can be finely adjusted by rotating the moving body (32) clockwise or counterclockwise with respect to the fixed member (31).
[0029]
When the flywheel rotating shaft (3) is not supported in a non-contact manner by the magnetic bearings (6), (7), (8), such as when the magnetic bearing device (4) is stopped, the flywheel rotating shaft (3) is mechanically supported by touchdown bearings (15), (16). At this time, the dimensions of the respective parts are determined so that the flywheel rotating shaft (3) does not contact the magnetic bearings (6), (7), (8), the sensors (9), (10), and (11).
[0030]
During operation of the magnetic bearing device (4), the position of the flywheel rotating shaft (3) detected by the axial sensor unit (9) in the Z-axis direction and the flywheel detected by the radial sensor unit (10) (11) By controlling the magnetic bearings (6), (7) and (8) based on the position of the wheel rotation shaft (3) in the X-axis and Y-axis directions, the flywheel rotation shaft (3) is moved in the axial and radial directions. Non-contact support at a predetermined position. Then, in this state in which the flywheel rotating shaft (3) is supported in a non-contact manner by the magnetic bearings (6), (7), and (8), the flywheel rotating shaft is driven by the stator unit (13) and the rotor (12) of the motor. (3) Therefore, the flywheel (2) integrated therewith is rotated at high speed.
[0031]
When controlling each magnetic bearing (6) (7) (8), the permanent magnet (18) of the axial magnetic bearing (6) attracts the flywheel rotating shaft (3) to flywheel unit (2) (3) Since the self-weight of (12) is retained, the electromagnetic coil (17) of the axial magnetic bearing (6) is supplied with current for supporting the self-weight of the flywheel unit (2) (3) (12). Instead, only the current for controlling the displacement due to the vibration in the axial direction is supplied. Then, by rotating the moving body (32) clockwise or counterclockwise with respect to the fixed member (31), the attractive force of the permanent magnet (18) is reduced by the weight of the flywheel unit (2) (3) (12). The control current of the axial magnetic bearing (6) can be minimized by setting so as to correspond exactly to. The support members (34) and (38) of the fixed member (31) and the movable body (32) are made of a material having good magnetic properties, and the screw members (33) of the fixed member (31) and the movable body (32). ) (37) is made of a high-strength and high-hardness material, the attractive force of the permanent magnet (18) increases, and this attractive force is applied to the screw members (33) (37). This prevents damage such as breakage.
[0032]
In the above embodiment, the configuration of each part of the magnetic bearing device (4) is not limited to that of the above embodiment, and can be changed as appropriate.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a mechanical part of a magnetic bearing device for a flywheel power storage device according to an embodiment of the present invention.
FIG. 2 is an enlarged longitudinal sectional view showing a main part of FIG.
[Explanation of symbols]
(3) Flywheel rotating shaft (rotating body)
(4) Magnetic bearing device
(6) Axial magnetic bearing
(7) (8) Radial magnetic bearing
(7a) (8a) Radial electromagnet
(17) Axial electromagnetic coil
(18) Permanent magnet
(19) Electromagnetic core (magnet support)
(20) Suction force adjustment means
(31) Fixing member
(32) Mobile object
(33) (37) Screw member
(33a) (37a) Threaded part
(34) (38) Support member

Claims (2)

Rotating body, multiple sets of magnetic bearings that support the rotating body in the axial and radial directions without contact, an axial sensor unit for detecting the axial position of the rotating body, and detecting the position of the rotating body in the radial direction In a magnetic bearing device comprising a radial sensor unit for
A permanent magnet that attracts and suspends the axial disk portion provided on the rotating body in the axial direction; and an attractive force adjusting means that adjusts the attractive force of the permanent magnet;
Suction force adjusting means, our a fixed member fixed to the magnet support member for supporting the permanent magnet, the moving body and the Bei Eteori opposed via a suction force adjusting gap magnet support, fixing member, the outer periphery The moving body has an annular screw member with a female screw part formed on the inner periphery, and the diameter of each screw member is larger than the outer diameter of the axial disk part. The moving body can be moved relative to the fixed member by being screwed together so that the screw members can move relative to each other, and the size of the suction force adjustment gap is the movement of the moving body. The magnetic bearing device is characterized in that the force for attracting the rotating body of the permanent magnet is adjusted by being changed by the above. Fixing member and the moving body each have a supporting annular member that is coupled to the member disposed on the upper side of the root Ji member, each support member includes a material having good magnetic properties than the screw member The magnetic bearing device according to claim 1, wherein the screw member is made of a material having higher strength than the support member.

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