JP5525348B2 - Magnetic levitation device - Google Patents

Description

Embodiments described herein relate generally to a magnetic levitation apparatus.

  Magnetic bearings are widely used as means for supporting a rotating body in a non-contact manner. Usually, a magnetic bearing is comprised by the radial bearing which carries out the non-contact support of the movement orthogonal to the rotating shaft of the rotating rotor, and the thrust bearing which carries out the non-contact support of the movement parallel to a rotating shaft. At that time, in order to stably support the rotor, which is a floating body, in a non-contact manner, a normal conducting attraction type magnetic levitation system that controls the attractive force of the electromagnet with respect to any bearing is generally applied. .

  Generally, in the normal conducting magnetic levitation method, when the attractive force is controlled by an electromagnet, a bias current is always supplied to obtain a steady support force of the levitating body and to ensure the stability of the control system. The attraction force must be formed by an electromagnet. Therefore, electric power is always consumed regardless of the disturbance acting on the rotor. This is not only a demerit from the viewpoint of power consumption, but since the electromagnet coil is always energized, it is inevitable to generate heat, and some cooling means must be taken.

  Further, in a conventional magnetic bearing using an electromagnet, it is common to design the gap length between the rotor and the electromagnet to be small in order to obtain a sufficient attractive force with the smallest possible electromagnet. However, when rotating the rotor in a special environment, for example, in a vacuum, if the entire magnetic bearing is installed in a vacuum, the heat dissipation effect cannot be expected, and overheating of the electromagnet may become a problem. Further, when the impeller is rotated as a rotor in a liquid like a can pump, if the entire magnetic bearing is placed in the liquid, the flow of the liquid is disturbed by the electromagnet, which is disadvantageous in terms of efficiency.

  In such a case, it is conceivable that the rotor that is a floating body is disposed in a vacuum vessel or a pipe, the electromagnet and the floating body are separated, and an electromagnet is disposed outside thereof to support the rotor in a non-contact manner. However, when the electromagnet is arranged outside the container or pipe, the gap length between the rotor and the electromagnet becomes wide, and there is a problem that the electromagnet is inevitably enlarged in order to obtain sufficient electromagnetic force to support the rotor. . Although it is possible to obtain a large electromagnetic force by increasing the electromagnet excitation current, there is a problem that in this case, the resistance loss of the electromagnet coil becomes large, the power consumption of the magnetic bearing increases and the heat generation amount also increases. .

  When performing attraction type magnetic levitation with low power consumption, a magnet unit is composed of permanent magnets and electromagnets, and the main magnetic flux caused by the permanent magnets and the magnetic circuit of the main magnetic flux caused by the electromagnets are separated by a gap between the levitated body and the magnet unit. There is a method of applying so-called zero power control in which a magnet unit and a floating body are arranged so as to form a common magnetic path, and the electromagnet excitation current is converged to zero while maintaining the stability of the floating state. By adopting such a configuration, the magnetic force required to support the levitated body in a non-contact manner can be provided by the magnetic force caused by the permanent magnet, and the bias current that needs to flow through the electromagnet for control stabilization. The need for is also eliminated. Therefore, a magnetic levitation system with low power consumption and low heat generation can be constructed. In addition, there is an advantage that a large electromagnetic force can be controlled with a slight electromagnet excitation current even when the gap length between the floating body and the magnet unit is large. In this way, by forming a magnetic bearing with a magnet unit composed of an electromagnet and a permanent magnet and a levitating body and applying zero power control, the rotor can be supported in a non-contact manner with a large gap. Therefore, the rotor placed in a container or pipe made of a non-magnetic material can be supported in a non-contact manner from the outside by the magnet unit.

JP 11-192224 A JP 61-102105 A

  However, when a magnetic bearing is configured by applying zero power control, the magnet unit generates an electromagnetic force that balances its magnitude against an external force that constantly acts. Since magnetic levitation control is performed so that it always converges to zero, the excitation current converges to zero and the gap length changes. As a result, magnetic levitation can be achieved only by the magnetic force of the permanent magnet without the need for excitation of the electromagnet. It is stabilized with. Therefore, when the weight of the rotor or an external force acting on the rotor acts on the magnetic bearing, the rotation center of the rotating body is displaced according to the external force. Displacement of the center of rotation causes a problem of run-out particularly in a device that rotates at a high speed, and in addition to the problem that the efficiency varies depending on the rotational position in a pump or the like, in some cases the rotor may be There is also the possibility of contact with containers and pipes.

  As a technique to solve such a problem, a magnet unit is supported by an elastic body for a magnetic levitation system to which zero power control is applied, and the change in the gap length that changes according to the magnitude of the acting external force is mechanically The absolute position of the floating body is maintained at a predetermined position. In this case, since the magnet unit is disposed in the movable frame and the movable frame is supported by the mechanical displacement absorbing mechanism, the entire magnetic levitation apparatus is increased in size. In particular, when the rotor is supported in a non-contact manner with respect to two shafts as a magnetic bearing, it is necessary to avoid that the control and behavior of each shaft are coupled. Must be arranged to operate independently. At that time, it is necessary to shift the installation position so that the operations do not interfere with each other, and the apparatus becomes particularly large in the axial direction. Also, by shifting the installation position, the point of action of the magnetic force acting on the rotor will differ, and in some cases it will be necessary to design different control parameters depending on the installation position, making control design complicated and difficult to ensure stability There is also a possibility of causing crystallization.

The problem to be solved by the present invention is to provide a magnetic levitation device capable of constituting a magnet unit and a movable frame without enlarging the size of the device when a magnetic force is applied from different directions in a magnetic levitation device having a displacement absorbing mechanism. There is to do.

  A magnetic levitation apparatus according to an embodiment includes a levitation body including a ferromagnetic body, a permanent magnet and an electromagnet provided on an outer periphery of the levitation body, a magnetic circuit of magnetic flux formed by the permanent magnet and the levitation body, and the electromagnet A magnet unit that forms a magnetic circuit of magnetic flux formed by the floating body, a movable frame that fixes the plurality of magnet units so that electromagnetic force acts on the floating body from different directions, and the movable frame, A fixed frame supported via a spring, a movable frame support means having a function of adjusting the distance between the fixed frame and the magnet unit, and the magnet unit of the floating body while converging the excitation current of the electromagnet to zero The magnet unit is disposed on a plane of the movable frame on which the magnet unit is orthogonal to a predetermined axis of the floating body.

The perspective view which shows 1st Embodiment. The perspective view which shows the vertical direction support apparatus in 1st Embodiment. The perspective view which shows the magnet unit in 1st Embodiment. The perspective view which shows the vertical direction movable frame in 1st Embodiment. The perspective view which shows the horizontal direction movable frame in 1st Embodiment. The perspective view which shows the vertical direction movable frame and horizontal direction movable frame in 1st Embodiment. The block diagram which shows the control apparatus in 1st Embodiment. The graph which shows the support force in 1st Embodiment. The perspective view which shows the vertical direction movable frame in 2nd Embodiment. The perspective view which shows 2nd Embodiment.

Hereinafter, a magnetic levitation apparatus according to an embodiment will be described with reference to the drawings.

(First embodiment)
The first embodiment will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the first embodiment. FIG. 2 is a perspective view showing the longitudinal support device in the first embodiment. FIG. 3 is a perspective view showing the magnet unit in the first embodiment. FIG. 4 is a perspective view showing the vertical movable frame in the first embodiment. FIG. 5 is a perspective view showing the laterally movable frame in the first embodiment. FIG. 6 is a perspective view showing the vertical movable frame and the horizontal movable frame in the first embodiment. FIG. 7 is a block diagram illustrating the control device according to the first embodiment. FIG. 8 is a graph showing the supporting force in the first embodiment.

(Constitution)
FIG. 1 shows a magnetic levitation apparatus in the first embodiment. The magnetic levitation apparatus 1 includes a fixed frame 3 that supports the entire apparatus, a vertical support apparatus 4 that supports the levitation body 2 in the y direction (up and down direction), and a lateral that supports the levitation body 2 in the x direction (left and right direction). It is comprised with the direction support apparatus 5. FIG.

  FIG. 2 shows a reference view in which the longitudinal support device 4 is taken out. The vertical support device 4 includes a vertical movable frame 6, a magnet unit 11 disposed on the upper and lower inner sides of the frame, and a gap sensor 12 and a vertical movable frame 6 disposed on the upper and lower inner sides of the frame. The linear guide support part 13 whose movement direction is operably limited, the linear guide rod 14 laid in the linear guide movement range, and the suspension 16 that elastically supports the vertical movement frame 6 with respect to the movement direction. The displacement absorbing mechanism 15 is configured. Here, the linear guide rod 14 engaged with the linear guide support portion 13 and the suspension 16 of the displacement absorbing mechanism 15 are partially connected to the fixed frame 3 of the magnetic levitation device 1. The displacement movable mechanism 15 supports the vertical movable frame 6 so as to be operable in a predetermined range, that is, in the vertical direction in the configuration shown in FIG.

  As shown in FIG. 3, the magnet unit 11 includes a permanent magnet 21, a yoke 22, and a coil 23 wound around the yoke 22, and has a U shape as a whole. Each coil 23 is connected in series, and when current is passed in the forward direction, the electromagnet 24 can be excited in a direction in which the magnetic flux formed by the permanent magnet 21 is strengthened. On the other hand, when a current is passed in the reverse direction, the electromagnet 24 can be excited in a direction that weakens the magnetic flux formed by the permanent magnet 21. As shown in FIG. 4, the magnet unit 11 is installed on the upper and lower inner sides of the vertical movable frame 6 so that the magnetic poles face each other.

  The vertical movable frame 6 to which the magnet unit 11 is attached is substantially U-shaped with one end as shown in FIG. Here, of each surface of the vertical movable frame 6, when the upper surface (+ y side) is 18a, the back surface (perpendicular to the z-axis) is 18b, and the lower surface (−y side) is 18c, the magnet unit 11 includes the upper surface 18a, And it is installed in the direction which makes a magnetic pole mutually oppose inside the lower surface 18c. The vertical movable frame 6 has a linear guide support portion 13 in a part thereof, and is engaged with a linear guide rod 14 connected to a part of the fixed frame 3 so as to be operable only in the vertical direction. Has been. Further, a slot 17 for allowing the floating body 2 to pass through is opened on the back surface 18b.

  Similarly, the lateral support device 5 can move the lateral movable frame 7 and the lateral movable frame 7 that move in the left-right direction by disposing two magnet units 11 composed of permanent magnets 21 and electromagnets 24 in an opposing positional relationship. Displacement absorption comprising a linear guide support portion 13 having a limited movable range, a linear guide rod 14 laid in the linear guide movable range, and a suspension 16 that elastically supports the lateral movable frame 7 in the operating direction. It consists of a mechanism 15. As in the longitudinal direction, a part of the linear guide and the displacement absorbing mechanism 15 is connected to the fixed frame 3 of the magnetic levitation apparatus 1, and the lateral movable frame 7 is configured by the linear guides 13 and 14 and the displacement absorbing mechanism 15. It is operably supported within a predetermined range.

  Similarly to the vertical movable frame 6, the horizontal movable frame 7 has a substantially U-shape with one end as an open end as shown in FIG. 5, and the right side (+ x 19a is the front side (orthogonal to the z-axis) is 19b, and the left side (−x side) is 19c, the magnet unit 11 is installed on the inner side of the right side 19a and the left side 19c so that the magnetic poles face each other. The Further, the laterally movable frame 7 has a linear guide support part 13 in a part thereof, and is engaged with a linear guide rod 14 connected to a part of the fixed frame 3 so as to be operable only in the left-right direction. Has been. Further, a slot 17 is formed in the front surface 19b for allowing the floating body 2 to pass through.

  The vertical movable frame 6 and the horizontal movable frame 7 are arranged in a direction in which the open ends thereof are opposed to each other as shown in FIG. 6, and the magnet units 11 installed in each are arranged on the same plane. It becomes the composition combined with. At the same time, slots 17 for penetrating the levitated body 2 in the axial direction perpendicular to the plane on which the magnet unit 11 is arranged are arranged at positions facing each other.

  The electromagnet 24 of each magnet unit 11 connects the coil 23 of each electromagnet 24 to the control device 31 to control the excitation voltage and support the levitated body 2 in a non-contact manner by zero power control. FIG. 7 shows a schematic diagram of the control device 31. The control device 31 detects a physical quantity in a magnetic circuit formed by the magnet unit 11 and the levitated body 2, and each of the control devices 31 to support the levitated body 2 in a non-contact manner based on a signal from the sensor portion 32. A control arithmetic unit 33 that calculates a voltage applied to the coil 23 and a driver 34 that supplies electric power to each coil 23 based on the output of the control arithmetic unit 33, by which the magnet unit 11 and the floating body 2 are configured. Controlling the magnetic force between. The sensor unit 32 is installed in each of the vertical movable frame 6 and the horizontal movable frame 7 to detect the distance between the magnet unit 11 and the levitated body 2 and the exciting current flowing in the coil 23 of the electromagnet 24. And a current sensor 35 for detecting. By performing feedback control with such a configuration, the voltage for exciting each coil 23 is controlled so that the levitated body 2 is supported with a gap between it and the magnet unit 11. Further, the detected value of the current sensor is fed back via an integrator while maintaining the magnetic support state by non-contact, so that the current is converged to zero, and the levitated body 2 is stably in non-contact with the magnet unit 11. When supported and in a steady state, the current flowing through each coil 23 can be converged to zero. As a result, all the forces required for stable support can be provided by the magnetic force generated by the permanent magnet 21, and so-called zero power control can be performed. At this time, even when a disturbance load due to a change in the weight of the levitating body 2 or a fluctuation in external force is applied, the levitating body 2 is transiently applied to the coil 23 so as to displace the load to a position where the magnetic force by the permanent magnet 21 is balanced. When the current flows again, but when it becomes stable again, the current flowing through the coil 23 is converged to zero by using the above-described control method, and the load and the permanent magnet applied to the levitated body 2 at that time The magnetic force of 21 will be balanced.

(Function)
Here, as described above, the vertical movable frame 6 and the horizontal movable frame 7 are connected to the fixed frame 3 by the displacement absorbing mechanism 15 configured by the spring suspension 16, so that the zero power control can stabilize the structure. When the floating body 2 is supported in a non-contact manner, the relationship shown in FIG. 8 is established. That is, since the magnetic force formed by the permanent magnet 21 by the zero power control and the sum of the loads composed of the weight and the external force of the levitated body 2 are balanced, the magnetic support characteristics in the figure are shown. Thus, as the load sum increases, the relative distance between the magnet unit 11 and the levitated body 2 is stabilized at a changed position. Furthermore, by supporting by the spring 16 having a displacement / restoring force characteristic equivalent to the displacement / attraction force characteristic due to the magnetic force, a characteristic having an inclination opposite to the magnetic support characteristic, such as the spring support characteristic in the figure, is obtained. Since the position of the levitated body 2 displaced by the zero power control will be displaced in the reverse direction by the spring 16, the load / displacement characteristics such as the composite support characteristics in the figure will result, Variations in the absolute position of the levitated body 2 are greatly reduced.

  Therefore, it is possible to construct a magnetic levitation device that can perform magnetic levitation without requiring steady power with zero power control and that the levitation position of the levitated body 2 hardly changes. Since this action has the same effect on the vertical movable frame 6 and the horizontal movable frame 7, as a result, power saving and floating body 2 can be performed regardless of the load such as external force in both the support directions. Thus, it is possible to realize a magnetic levitation device or a magnetic bearing with less support position fluctuation.

  Furthermore, the vertical movable frame 6 and the horizontal movable frame 7 are substantially U-shaped, and the magnet units 11 are arranged on the same plane with the open ends facing each other, thereby positioning the vertical movable frame 2 and the horizontal movable frame 2 in the vertical and horizontal directions. The four magnet units 11 are configured to form a magnetic force in the same space. Further, by placing the floating body 2 on the magnetic force forming portion formed by each magnet unit 11, each magnet unit 11 can cause a magnetic force to act on the same portion of the floating body 2. Therefore, it is not necessary to dispose the two orthogonal magnet units 11 in the axial direction of the levitation body 2, and the magnetic levitation device 1 or the magnetic bearing portion can be shortened in the axial direction. This can greatly reduce the overall size of the magnetic levitation device, and can reduce the size and weight of the levitation body 2. Moreover, since the action position of the magnetic force is the same in both the vertical direction and the horizontal direction, the control system parameters for supporting the levitated body 2 in a non-contact manner can be the same. Furthermore, it becomes difficult to produce a difference in the behavior in the vertical direction and the horizontal direction, and it becomes easier to realize a stable non-contact support. In addition, since the magnet unit 11, the vertical support device 4, and the horizontal support device 5 that control the directions of each other are separated from each other, the movable frame and the floating body in each direction are caused by interference between the control system and the support position. As a result, the magnetic levitation apparatus 1 can be configured more stably.

(effect)
According to the magnetic levitation device of at least one embodiment described above, when a magnetic force is applied from different directions in a magnetic levitation device having a displacement absorbing mechanism, a magnet unit and a movable frame that do not entail an increase in size of the device are configured. it can. Accordingly, even when zero power control is applied as described above to achieve magnetic levitation by power saving, fluctuations in the absolute position of the levitated body can be suppressed, and the apparatus can be configured with less space.

(Second Embodiment)
The second embodiment will be described in detail with reference to the drawings. FIG. 9 is a perspective view showing a vertical movable frame in the second embodiment. FIG. 10 is a perspective view showing the second embodiment. In addition, about the thing which has the same structure as FIG.

In the present embodiment, a configuration for improving the strength of the movable frame while having the characteristics of the first embodiment will be described.

(Constitution)
FIG. 9 shows the shape of the longitudinally movable frame 6 in the second embodiment. The U-shaped vertical movable frame 6 having an open end may be deformed inward by the magnetic force of the magnet unit 11. In order to suppress inward deformation, a reinforcing rib 41 is provided between the upper surface 18a and the lower surface 18c and the back surface 18b. Further, a reinforcing rod 42 is installed between the upper surface 18a and the lower surface 18c on the open end side. Similarly, the same reinforcement is applied to the laterally movable frame 7. The reinforcing rib 41 can maintain the shape by suppressing the stress when the upper surface 18a and the lower surface 18c are deformed inward by the magnetic force. The reinforcing rod 42 can significantly reduce deformation when the open end sides of the upper surface 18a and the lower surface 18c receive a force that deforms inward.

Further, each reinforcing member is arranged in the vertical movable frame 6 in a range that does not interfere with the movable range of the horizontal movable frame 7 and the magnetic force acting range of the magnet unit 11 installed in the horizontal movable frame 7. Further, by adopting the same configuration, the reinforcing members arranged in the horizontal movable frame 7 are also arranged without affecting the operating range of the vertical movable frame 6 and the magnetic force acting range of the magnet unit 11. be able to.

By arranging and combining the reinforcing members at these locations, as shown in the overall view of FIG. 10, the interference between the movable range of the movable frame in the other direction and the magnetic force acting range of the magnet unit 11 is avoided, and the mutual behavior is affected. The strength of the vertical direction movable frame 6 and the horizontal direction movable frame 7 can be improved without giving any. Further, the magnetic levitation apparatus of the present embodiment can be configured with only one of the reinforcing rib 41 and the reinforcing rod 42.

As in the first embodiment, in the second embodiment, the linear guide support portion 13 that enables the movable frame in each direction to operate in one direction is opposite to the open end of the U-shaped movable frame. By disposing in the vicinity of the back surface 18b and the front surface 19b, the movable frame can be supported by a portion having a relatively high shape in shape, and can be configured to be more difficult to deform. Similarly, by disposing the displacement absorbing mechanism 15 on the side opposite to the open end of the U-shaped movable frame, the supporting force for suppressing the displacement of the levitated body 2 with respect to the force generated by the disturbance is relatively strong. It can be received at a high portion, and can have a more structurally strong and stable shape.

(effect)
According to the magnetic levitation device of at least one embodiment described above, when a magnetic force is applied from different directions in a magnetic levitation device having a displacement absorbing mechanism, a magnet unit that does not increase in size of the device and a stronger A movable frame can be configured. Accordingly, even when zero power control is applied as described above to achieve magnetic levitation by power saving, fluctuations in the absolute position of the levitated body can be suppressed, and the apparatus can be configured with less space.

1 ... Magnetic support device (magnetic bearing)
2 Floating body (rotating shaft)
DESCRIPTION OF SYMBOLS 3 ... Fixed frame 4 ... Vertical direction support apparatus 5 ... Horizontal direction support apparatus 6 ... Vertical direction movable frame 7 ... Horizontal direction movable frame 11 ... Magnet unit 12 ... Gap sensor 13 ... Linear guide support part 14 ... Linear guide rod 15 ... Displacement Absorption mechanism 16 Suspension (spring)
17 ... Slot 18a ... Upper surface 18b ... Back surface 18c ... Lower surface 19a ... Right surface 19b ... Front surface 19c ... Left surface 21 ... Permanent magnet 22 ... Relay 23 ... Coil 24 ... Electromagnet 31 ... Control device 32 ... Sensor unit 33 ... Control calculator 34 ... Driver 35 ... Current sensor 41 ... Rib 42 ... Reinforcing rod

Claims (9)

A levitated body with a ferromagnetic body;
A magnet unit that is provided on an outer periphery of the levitating body, includes a permanent magnet and an electromagnet, and causes the electromagnetic force formed by the permanent magnet and the electromagnet to act on the levitating body;
A movable frame that fixes the plurality of magnet units so that electromagnetic force acts on the floating body from different directions;
A movable frame support means having a function of adjusting a distance between a fixed frame for fixing the movable frame via an elastic body and the magnet unit;
Control means for supporting the floating body in a non-contact manner from the magnet unit while converging the excitation current of the electromagnet to zero,
The magnetic levitation apparatus, wherein the magnet unit installed on the movable frame is arranged on the same plane perpendicular to a predetermined axis of the levitation body. The movable frame supports the two magnet units at both diagonal positions with the floating body interposed therebetween, and the magnet unit is opposed to the floating body from two directions orthogonal to the floating body. The magnetic levitation apparatus according to claim 1, wherein at least two magnet frames are provided around the levitation body. 3. The magnetism according to claim 2, wherein the movable frame has a substantially U-shape with an open shape in one direction, and two movable frames are arranged so as to have surfaces facing each other. Levitation device. The magnetic levitation apparatus according to claim 3, wherein a reinforcing rib is provided on a side opposite to the open end of the movable frame. 4. The magnetic levitation apparatus according to claim 3, wherein a part of the open end of the movable frame is connected by a rod-shaped member. 2. The magnetic levitation apparatus according to claim 1, wherein the movable frame is restricted in an operation range so as to move in one direction by a support member capable of translational movement. The said support member is connected with a part of said movable frame, and the said fixed frame, The connection part with the said movable frame is provided in the opposite side to the open end. Magnetic levitation device. The magnetic levitation apparatus according to claim 1, wherein the levitation body has a columnar or cylindrical shape and is a rotating body. The magnetic levitation apparatus according to claim 1, wherein the movable frame support means includes an elastic element.