JP4753004B2 - Electromagnet unit, electromagnetic actuator, levitation control device for electromagnetic actuator, and stage device - Google Patents

Description

The present invention relates to an electromagnet unit used as a levitation system of a magnetic levitation transfer stage that moves along a guide rail while levitation in a clean room such as a semiconductor manufacturing factory, an electromagnetic actuator using the same, and levitation control of the electromagnetic actuator The present invention relates to a device and a stage device using this electromagnetic actuator.

Conventionally, as a transfer device in a clean room such as a semiconductor manufacturing factory, a magnetic levitation transfer stage that travels along a guide rail while levitation is used. A plurality of electromagnet units in which an E-shaped core and an I-shaped core, or a C-shaped core and an I-shaped core are combined are used in the magnetic levitation conveyance stasis (see, for example, Patent Document 1). Here, an electromagnet unit in which an E-shaped core and an I-shaped core are combined will be described.
4 is a front sectional view of an electromagnet unit showing the first prior art, and FIG. 5 is a side sectional view taken along the line CC (center line) of FIG.
4 and 5, 21 is an electromagnet unit, 22 is a second core, 23 is an exciting coil, 24 is a permanent magnet, and 25 is a first core.
One of the electromagnet units is composed of a first core 25 having an I-shaped cross section made of a magnetic material. The other of the electromagnet units is disposed opposite to the first core 25 via a gap, and is wound around an E-shaped second core 22 made of a magnetic material and a central leg 22A of the second core 22. The exciting coil 23 that generates a magnetic force and a permanent magnet 24 provided on a surface of the second core 22 facing the first core 25 of the central leg 22A. In general, one of the first core 25 and the second core 22 in the figure is fixed to a moving stage (not shown) to form a mover, and the other is fixed to a fixed base (not shown) to form a stator. It is supposed to be.
In such a configuration, a gap sensor (not shown) is provided facing the gap G between the first core 25 and the second core 22, and information from the gap sensor (not shown) is fed back to the exciting coil 23 with a predetermined current. To generate a magnetic levitation force between the first core 25 and the second core 22 so that the mover is levitated .
FIG. 6 is a front sectional view of an electromagnet unit showing the second prior art, and FIG. 7 is a side sectional view taken along line CC (center line) in FIG. The electromagnet unit of the second prior art is the same as the first prior art in that an E-shaped core and an I-shaped core are combined, but a permanent magnet 24 is formed at the center of the first core 25. The difference is that it is provided in the groove. Since the operation is the same as that of the first prior art, description thereof is omitted.
JP 2001-231111 A

However, in the first prior art, when a long stroke is required for the mover of the magnetic levitation transfer stage, it is necessary to divide the permanent magnet attached to the second core of the electromagnet unit. As a result, there has been a problem that attraction force fluctuation occurs in the permanent magnet dividing portion, vibration due to thrust ripple occurs, and positioning accuracy is affected.
Further, in the second prior art, when either the first core or the second core is displaced in the X direction, the component of the magnetic attraction force becomes a restoring force and axial interference occurs, and the Y direction or There is a problem that control in the Z direction becomes difficult.
The present invention has been made in view of such problems, and suppresses the generation of vibration due to thrust ripple, and when the core is displaced in the X direction, the component force of the magnetic attractive force becomes a restoring force. An object of the present invention is to provide an electromagnetic unit, an electromagnetic actuator, a floating control device for an electromagnetic actuator, and a stage device that can suppress axial interference that occurs and can easily perform control in the Y and Z directions, and that can achieve high positioning accuracy. .

  In order to solve the above problem, the present invention is configured as follows.

The invention of claim 1 includes a stator and a mover, and one of the stator and the mover includes a first core having an I-shaped cross section made of a magnetic material, and a central portion of the first core. A permanent magnet provided in a groove formed at a position, and the other of the stator and the mover is arranged to face the first core via a gap and is made of a magnetic material. A configuration in which an electromagnet having a cross-sectional second core and an exciting coil wound around a central leg of the second core and generating a magnetic force is provided, and the mover floats in the gap direction with respect to the stator Yes and the spread width of the facing surfaces of the first core of the central leg of the second core Rutotomoni, window opening formed between the legs positioned at the center leg and both ends of the second core Is characterized by having a semi-closed slot shape.

  According to a second aspect of the present invention, in the electromagnet unit according to the first aspect, the permanent magnet is provided with inclined chamfered portions at both ends of the surface facing the second core.

  The invention according to claim 3 is the electromagnet unit according to claim 1, characterized in that the width A of the central leg of the second core is about 60% to 70% of the groove width B of the first core. .

  The invention of claim 4 is an invention related to an electromagnetic actuator, characterized in that a plurality of electromagnet units according to any one of claims 1 to 3 are provided.

A fifth aspect of the present invention is an invention related to a levitation control device for an electromagnetic actuator, wherein the electromagnetic actuator according to the fourth aspect is provided between a first core and a second core of an electromagnet unit constituting the electromagnetic actuator. A gap sensor for detecting a gap, a current sensor for detecting a current flowing in an exciting coil of the electromagnet, a force command corresponding to a target magnetic force generated by the electromagnet unit, and a gap signal detected by the gap sensor are input. A force / current conversion means for outputting a current command, a current control unit for calculating a voltage command based on a deviation between the current command and the current signal of the exciting coil detected by the current sensor, and the current control unit A power amplifier adapted to apply an excitation voltage to the excitation coil by amplifying the voltage command obtained in It is characterized in that was.

A sixth aspect of the invention relates to a stage apparatus, wherein the electromagnetic actuator according to the fourth aspect of the invention is used as a stage floating means.

  According to the first aspect of the present invention, the generation of vibration due to the thrust ripple is suppressed, and when the core is displaced in the X direction, the axial interference caused by the component force of the magnetic attractive force is suppressed, and Y , Control in the Z direction can be easily performed.

  According to the second aspect, since the magnetic flux at the end of the permanent magnet is lowered, the X-direction component of the magnetic attractive force when the core is displaced in the X direction can be reduced. However, there is no interference with the linear motor for driving in the X direction, and the positioning accuracy in the X direction can be improved.

  According to claim 3, the magnetic attractive force generated between the central leg end of the second core and the first core groove end, and the restoring force generated at the permanent magnet 4 and the central leg end of the second core. In balance, axial interference can be made almost zero.

  According to the fourth aspect, when an electromagnetic actuator is designed using a plurality of electromagnet units, the degree of freedom in structure increases and high positioning accuracy can be obtained.

  According to the fifth aspect, the force according to the command can be generated in the electromagnetic actuator composed of the plurality of electromagnet units by using the force / current conversion means.

According to the sixth aspect, high positioning accuracy can be obtained by using the stage device that is levitated by the electromagnetic actuator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the description is abbreviate | omitted about the same component of this invention as a prior art, and a different point is demonstrated.

FIG. 1 is a front sectional view of an electromagnet unit showing a first embodiment of the present invention.
In the figure, 1 is an electromagnet unit, 2 is a second core, 3 is an exciting coil, 4 is a permanent magnet, and 5 is a first core.
One of the electromagnet units of the present invention is composed of a first core 5 having an I-shaped cross section made of a magnetic material and a permanent magnet 4 provided in a groove formed at the center of the first core 5. The other end of the electromagnet unit is disposed opposite to the first core 5 with a gap between the second core 2 having an E-shaped cross section made of a magnetic material and the center leg 2A of the second core 2. It is the same as the second prior art in that it is composed of an electromagnet having an exciting coil 3 that is wound and generates a magnetic force.
The present invention differs from the second prior art in that the width of the surface of the second core 2 facing the first core 5 of the center leg 2A is widened, and the center leg 2A of the second core 2 and the legs positioned at both ends are The window opening 2B formed between the two is shaped like a semi-closed slot.
Further, the permanent magnet 4 is provided with chamfered portions 4 </ b> A inclined at both ends of the surface facing the second core 2.
Further, the width A of the central leg 2A of the second core 2 is set to about 60% to 70% of the groove width B of the first core 5.

FIG. 2 is a perspective view showing an overview of a magnetic levitation transfer stage apparatus including a four-point support moving body to which a plurality of electromagnet units of the present invention are applied.
The electromagnet unit 1 shown in FIG. 1 is, for example, arranged in four positions at P ₁ , P ₂ , P ₃ , P ₄ of the moving body M in the magnetic levitation transfer stage device shown in FIG. One electromagnetic actuator that floats and supports the body M at four points is configured. For this reason, the movable body M of the stage apparatus is controlled to move in parallel with the direction connecting P ₁ and P ₃ , P ₂ and P ₄ of the electromagnet unit 1 by a non-contact linear motor (not shown).

Next, a levitation control device for an electromagnetic actuator using the plurality of electromagnet units 1 shown in FIG. 2 will be described with reference to FIG. Here, for convenience, description will be made using one electromagnet unit.
FIG. 3 is a control block diagram for explaining the floating control of the electromagnetic actuator using the electromagnet unit.
As a levitation control device for an electromagnetic actuator, an electromagnetic actuator comprising a plurality of electromagnet units 1 and a gap sensor 6 for detecting a gap between the first core 5 and the second core 2 of the electromagnet unit 1 constituting the electromagnetic actuator. And a current sensor 8 for detecting a current flowing in the exciting coil 3 of the electromagnet, a force command f corresponding to a target magnetic force generated by the electromagnet unit 1 and a gap signal h detected by the gap sensor 6 a force / current converter 9 that outputs a current command I _r, based on the deviation of the current command I _r and the current signal I of the excitation coil 3 detected by the current sensor 8 to calculate the voltage command U _r by a current control unit 10, by amplifying the voltage command U _r obtained in said current control unit 10, so as to provide an excitation voltage to the excitation coil 3 And a power amplifier 7.

Next, the operation of the levitation control using the electromagnet unit 1 according to the present invention will be described with reference to FIG.
In FIG. 3, the gap sensor 6 detects the gap h between the first core 5 and the second core 2, and the force / current conversion means 9 is a force command f _r corresponding to the target magnetic force generated by the electromagnet unit 1. and based on the gap signal h detected by the gap sensor, it calculates a current command I _r, for example, by using an electromagnet of the magnetic circuit model. Subtractor 11 is the current command I _r and the current sensor 8 calculates the deviation between the current I of the excitation coil 3 detected, the current control unit 10 is a current command I _r and current I of the excitation coil 3 by the current sensor 8 detects calculating the voltage command u _r based on a deviation between. Power amplifier 7 provides an excitation voltage to the excitation coil 3 of the electromagnet by amplifying the voltage command u _r. Thus, the electromagnetic actuator can be controlled to generate a magnetic levitation force as commanded in the electromagnet unit 1 by converting the force command into a current command by using the levitation control device.

In an embodiment of the present invention, one of the electromagnet units has a first core 5 having an I-shaped cross section made of a magnetic material, and a permanent magnet provided in a groove portion formed at the center of the first core 5. 4 and the other end of the electromagnet unit is disposed opposite to the first core 5 via a gap, and the second core 2 having an E-shaped cross section made of a magnetic material and the center leg of the second core 2 2A and an electromagnet having an exciting coil 3 that generates a magnetic force . (1) The width of the second core 2 facing the first core 5 of the center leg 2A is increased, A configuration in which the window opening 2B formed between the center leg 2A of the two cores 2 and the legs located at both ends has a semi-closed slot shape, and (2) the permanent magnet 4 is A configuration in which inclined chamfered portions 4A are provided at both ends of the opposing surface, (3) and the inside of the second core 2 Since the width A of the central leg 2A is set to about 60% to 70% of the groove width B of the first core 5, even if the positional relationship between the mover and the stator is shifted in the X direction, the electromagnetic unit is attracted. The force is generated only in the Z direction and does not become a disturbance in the X direction. In addition, since the gravity in the Z direction is canceled by the attractive force of the permanent magnet, a small and highly controllable electromagnet unit can be realized.

In the electromagnetic actuators of the embodiments , one of the electromagnet units is a mover having a first core and a permanent magnet, and the other electromagnet unit is a stator having an electromagnet having a second core and an excitation coil. However, the movable element and the stator may be reversely arranged.
Moreover, although the 2nd core 2 has E-shaped cross-sectional shape, a shape is not limited, For example, a C-shaped column shape may be sufficient.
Further, the central leg of the second core is not limited to the one having a uniform and uniform cross section in the longitudinal direction perpendicular to the paper surface of FIG. 1, and has a partially different cross section. Also good.

  The technology of the present invention can be applied not only to magnetic levitation conveyance in a clean room such as a semiconductor manufacturing factory, but also to conveyance in the manufacturing field of liquid crystal substrates, electronic circuit devices, ultra-precision parts, and the like.

Front sectional view of an electromagnet unit showing a first embodiment of the present invention It is the perspective view which showed the general view of the magnetic levitation conveyance stage apparatus provided with the moving body of 4 point | piece support to which the electromagnet unit of this invention was applied in multiple numbers. Control block diagram for explaining levitation control using an electromagnet unit Front sectional view of an electromagnet unit showing the first prior art, Side sectional view along CC line (center line) of FIG. Front sectional view of an electromagnet unit showing the second prior art, Side sectional view along CC line (center line) of FIG.

DESCRIPTION OF SYMBOLS 1 Electromagnet unit 2 2nd core 2A Center leg 2B Window opening part 3 Excitation coil 4 Permanent magnet 4A Chamfer part 5 1st core 6 Gap sensor 7 Power amplifier 8 Current sensor 9 Force / current conversion means 10 Current control part 11 Subtractor M Moving body

Claims (6)

With stator and mover,
One of the stator and the mover includes a first core having an I-shaped cross section made of a magnetic material, and a permanent magnet provided in a groove formed at the center of the first core. ,
The other of the stator and the mover is disposed opposite to the first core via a gap, and has an E-shaped cross-sectional second core made of a magnetic material, and a central leg of the second core. An electromagnet having an excitation coil wound and generating a magnetic force;
The mover is configured to float in the gap direction with respect to the stator,
Said second broaden opposing surfaces of the first core of the central leg of the core Rutotomoni, window opening formed between the legs positioned at the center leg and both ends of the second core half-closed slots An electromagnet unit characterized by having a shape.     2. The electromagnet unit according to claim 1, wherein the permanent magnet has inclined chamfered portions at both ends of a surface facing the second core.     2. The electromagnet unit according to claim 1, wherein a width A of a central leg of the second core is about 60% to 70% of a groove width B of the first core.     An electromagnetic actuator comprising a plurality of electromagnet units according to any one of claims 1 to 3. An electromagnetic actuator according to claim 4,
A gap sensor for detecting a gap between the first core and the second core of the electromagnet unit constituting the electromagnetic actuator;
A current sensor for detecting a current flowing in an excitation coil of the electromagnet;
Force / current conversion means for outputting a current command by inputting a force command corresponding to a target magnetic force generated by the electromagnet unit and a gap signal detected by the gap sensor;
A current control unit that calculates a voltage command based on a deviation between the current command and the current signal of the exciting coil detected by the current sensor;
By amplifying the voltage command obtained by the current control unit, a power amplifier configured to give an excitation voltage to the excitation coil;
A levitation control device for an electromagnetic actuator, comprising: 5. A stage apparatus, wherein the electromagnetic actuator according to claim 4 is used as a stage floating means.

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