JP2004129316A - Linear motor actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator which can secure space for air between a moving member and a stator by preventing the stator from flexing to cause contact with the moving member. <P>SOLUTION: For the bar-shaped stator 3 having a field magnet, both its ends are supported by a base 1. The moving member 4 capable of axial movement is set to the stator 3. A movement guide device 7 guides the moving member into movement in axial direction of the stator 3 while supporting the load of the moving member 4, and is arranged between the base 1 and the moving member 4. Bearings 8 and 8, which restrains the stator from flexing so that the moving element may not contact with the stator 3, are provided at one end at least in the shifting direction of the moving member 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a linear motor actuator in which a mover having a coil relatively moves with respect to a rod-shaped stator having a field magnet in which N magnetic poles and S magnetic poles are alternately arranged.
[0002]
[Prior art]
There is known a linear motor actuator in which a mover having a coil relatively moves with respect to a rod-shaped stator having a field magnet in which N magnetic poles and S magnetic poles are alternately arranged. When a current corresponding to the polarity of the magnetic pole is applied to each field of the coil surrounding the stator, a thrust is generated in the mover due to the interaction between the current and the magnetic field formed by the field magnet (for example, see Patent Document 1). 1).
[0003]
[Patent Document 1]
JP-A-11-150973
[Problems to be solved by the invention]
It is desirable that the mover moves without contacting the stator, that is, with an air gap between the mover and the stator. This is because when the mover contacts the stator, the contacted portion becomes a resistance, and a large amount of current flows through the coil of the mover.
[0005]
When the length of the rod-shaped stator is short and the stroke of the mover is short, the mover does not contact the stator. However, when the length of the stator is long and the stroke of the mover is long, the stator bends due to the effect of its own weight and suction force, and the air gap between the mover and the stator cannot be maintained. Would.
[0006]
Therefore, the present invention provides a linear motor actuator capable of preventing the stator from bending and causing the mover and the stator to come into contact with each other and securing a gap between the mover and the stator. Aim.
[0007]
[Means for Solving the Problems]
Hereinafter, the present invention will be described. In order to solve the above problems, the present invention has a field magnet, a rod-shaped stator whose both ends are supported, and a coil fitted to the stator, which can move in the axial direction of the stator. Mover, a movement guide device that guides the mover in the axial direction of the stator while supporting the load of the mover, attached to at least one end in the moving direction of the mover, The above-mentioned object is achieved by a linear motor actuator comprising: a bearing that suppresses bending of the stator so that the mover does not contact the stator.
[0008]
According to the present invention, even when the stator is long and the stroke of the mover is long, the mover can operate without contacting the stator.
[0009]
It is desirable that the bearing be an air bearing that blows compressed air between a stator and the bearing to support the load of the stator with air pressure.
[0010]
According to the present invention, the air bearing lifts the bent stator to suppress the stator from bending. In addition, when the air bearing is used, the frictional force and the fluctuation of the frictional force when the air bearing moves in the axial direction are smaller than when the ball bush or the slide bearing are used, so that the mover is moved at a constant speed. be able to.
[0011]
Further, the motion guide device has a track member that extends elongated in parallel with the stator, and a moving member that is attached to the mover and that can move along the track member. The track member and the moving member It is preferable that compressed air is blown in between the moving member and the moving member to be lifted by air pressure.
[0012]
According to the present invention, the frictional force generated by the motion guide device can be reduced, and the mover can be moved at a more constant speed.
[0013]
Further, it is preferable that the compressed air blown between the stator and the bearing flows into a gap between the stator and the mover so that the mover can be cooled.
[0014]
Further, the present invention includes a base that is elongated and elongated, a rod-shaped stator having a field magnet, both ends of which are supported by the base while extending in the longitudinal direction of the base, and a coil that is fitted to the stator. A movable element movable in the axial direction of the movable element, and a movable element arranged between the base and the movable element to guide the movable element moving in the axial direction of the stator while supporting the load of the movable element. And a pneumatic bearing attached to at least one end of the mover in the moving direction of the mover.
[0015]
Further, it is desirable that the bearing or the air bearing is attached to both ends of the mover in the moving direction.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a side view of a linear motor actuator according to an embodiment of the present invention. The linear motor actuator is used, for example, as an X-axis and Y-axis actuator of a semiconductor manufacturing apparatus. More specifically, it is suitably used for an actuator or the like for coating a thin film on a substrate for a large liquid crystal display, which requires a relatively large stroke.
[0017]
The elongated base 1 has support plates 2, 2 at both ends in the longitudinal direction, and both ends of a rod-shaped stator (hereinafter, referred to as a rod 3) are fixed to the support plates 2, 2. A mover 4 having a coil is fitted on the rod 3. The mover 4 is guided by a movement guide device 7 disposed between the mover 4 and the base so as to be movable in the axial direction of the rod 3 while supporting a load. A pair of air bearings 8, 8 are attached to both ends of the mover 4 in the moving direction.
[0018]
FIG. 2 shows the rod 3 and the mover 4. The rod 3 has a circular cross section and its surface is processed smoothly. The rod 3 has a plurality of permanent magnets 3a having N magnetic poles and S magnetic poles. The plurality of permanent magnets 3a are alternately arranged so that N poles and S poles face each other (see FIG. 3). As a result, a driving magnetized portion in which N-poles and S-poles are alternately arranged along the longitudinal direction of the rod 3 is formed, and this is a field magnet.
[0019]
The mover 4 is configured by housing a cylindrical coil 4b in a housing 4a formed in a quadrangular prism shape as a whole. The bottom surface of the housing 4a is attached to the moving blocks 5 and 5 of the motion guide device 7, and the upper surface is attached to a moving object. A plurality of grooves are formed in the housing 4a, thereby forming fins for releasing heat generated in the coil.
[0020]
3 and 4 show the operation principle of the linear motor. The coil 4b has a coil group in which three coils of the U, V, and W phases constitute one set. Each phase coil is ring-shaped, and is wound around the outer periphery of the rod 3 with a gap. The pitch of the coils of each phase is set shorter than the pitch of the permanent magnet 3a.
[0021]
A magnetic flux 10 is formed on the rod 3 from the S pole to the N pole. The mover 4 has a built-in magnetic pole sensor (not shown), and the magnetic pole sensor detects the positional relationship between each coil and the magnetic pole of the field magnet in the longitudinal direction of the rod 3. The signal of the magnetic pole sensor is input to the driver, and the driver calculates and flows an optimal current to the coil 4b according to the positional relationship between each coil and the field magnet. When a current flows through each coil 4b, the mover moves in the axial direction of the stator due to the interaction between the current flowing through each coil 4b and the magnetic flux 10 formed by the field magnet.
[0022]
5 and 6 show the air bearings 8 attached to both ends of the mover 4 in the moving direction. The air bearing 8 has an air pad 8a formed in a cylindrical shape so as to surround the rod 3, and an annular fluid chamber 8b is formed in the air pad 8a. From the fluid chamber 8b, air outflow holes 8c facing the gap between the rod 3 and the air pad 8a are formed at equal intervals in the circumferential direction. When compressed air is blown into the air pad 8a, the compressed air is blown into the gap between the rod 3 and the air pad 8a via the air passage such as the fluid chamber 8b and the air outflow hole 8c.
[0023]
When the stroke of the rod 3 becomes long, the rod 3 is bent by its own weight or by the attraction force of the magnetic force, and its central part is lowered. The air bearing 8 supports the load of the bent rod 3 and lifts the rod 3 from, for example, a position indicated by a two-dot chain line in FIG. 5 to a position indicated by a solid line. The specifications of the air bearing 8, such as the pressure of the compressed air and the size of the pad, are selected according to the load of the rod 3 to be supported.
[0024]
7 and 8 show a movement guide device 7 interposed between the base 1 and the mover 4 and guiding the mover 4 to move. The motion guide device 7 includes a track rail 12 as a track member extending linearly and elongated, and a moving block 13 as a moving member that is slidably attached to the track rail 12. The track rail 12 is mounted on the upper surface of the base 1, and the mover 4 is mounted on the upper surfaces of the moving blocks 5, 5. Between the track rail 12 and the moving block 13, there are interposed a number of rolling balls made of metal balls 14.
[0025]
The track rail 12 has ball rolling grooves 12a extending in the longitudinal direction and serving as tracks when the ball rolls. The ball rolling grooves 12a are formed, for example, two on each of the left and right sides, for a total of four.
[0026]
The moving block 13 includes a central portion 13 a facing the upper surface of the track rail 12, and side wall portions 13 b extending downward from both left and right sides of the central portion 13 a and facing the left and right side surfaces of the track rail 12. A loaded ball rolling groove is formed inside the moving block 13 so as to face the ball rolling groove and serve as a trajectory when the ball rolls. The moving block 13 has a ball return path provided in parallel with the ball rolling grooves 12a at a predetermined interval, and a U-shaped direction change connecting both ends of the loaded ball rolling grooves and both ends of the ball return path. A path is formed. A ball circulation path is formed by the loaded ball rolling grooves, the direction change path, and the ball return path.
[0027]
The plurality of balls 14 are connected in series by a ball retainer 15. The ball retainer 15 is composed of a plurality of spacers 15a having concave surfaces on both sides thereof, the concaves being formed on the outer surfaces of the adjacent balls 14 and being interposed between the balls 14 and connecting portions 15b connecting the spacers 15a. Be composed. By holding the balls 14 rotatably and slidably by the ball retainer 15, the balls 14 roll smoothly, and the moving block 13 can slide smoothly on the track rail 12.
[0028]
As shown in FIG. 1, since the mover 4 is supported by the motion guide device 7, it can move in the axial direction of the rod 3, but cannot move in the direction orthogonal to the axis of the rod 3. I have. For this reason, when the stroke of the rod 3 becomes long and the rod 3 is bent by its own weight or by the attraction force of the magnetic force and its central part is lowered, the rod 3 may come into contact with the coil 4b of the mover 4. However, when the air bearings 8, 8 are arranged at both ends in the axial direction of the mover 4 as in the present embodiment, the air bearings 8, 8 support the bent rod 3 and lift the rod 3, so that the rod 3 is lifted. 3 can be prevented from contacting the coil 4b.
[0029]
Even if the air bearing 8 is arranged only at one end in the moving direction of the mover 4, the bent rod can be lifted, so that contact between the rod 3 and the coil 4b can be prevented. If the air bearings 8, 8 are arranged at both ends in the moving direction of the mover 4, the rod 3 can be lifted evenly on both sides in the moving direction of the mover 4, so that the contact between the rod 3 and the coil 4b can be further prevented. Can be.
[0030]
In the present embodiment, an air bearing is used as the bearing 8, but a bearing such as a ball bush or a sliding bearing can be used in addition to the air bearing. These bearings can also lift the rod 3 while supporting the load of the bent rod 3, so that contact between the rod 3 and the coil 4b can be prevented.
[0031]
In some cases, such as when the linear motor actuator is used to apply a film having a constant thickness to a large liquid crystal display substrate, there is a case where it is desired to move the mover 4 with respect to the stator 3 at a constant speed. When the air bearing 8 is used as in the present embodiment, the frictional force and the fluctuation of the frictional force when the air bearing 8 moves in the axial direction are reduced as compared with the case of using a ball bush, a slide bearing, or the like. The mover 4 can be moved at a constant speed without the following.
[0032]
Further, the compressed air blown between the stator 3 and the air bearing 8 is caused to flow into the gap between the stator 3 and the mover 4, thereby cooling the coil 4b of the mover 4. You can also.
[0033]
FIG. 9 shows another example of the exercise guide device. In this example, the motion guide device 20 is attached to the base 1, a track rail 21 as a track member that extends elongated in parallel with the stator 3, and is attached to the mover 4 as a movable member that can move along the track rail 21. And a moving block 22. Air pads 23 are incorporated in the moving block 22. The air pads 23 blow compressed air between the track rail 21 and the moving block 22 to float the moving block 22 by air pressure. When the moving block 22 is lifted as in this example, the frictional force generated by the motion guide device 20 can be reduced, and the mover 4 can be moved at a more constant speed.
[0034]
Note that, in the above embodiment, an example was described in which a linear motor actuator was applied to coat a thin film on a substrate for a liquid crystal display. It can be used for various applications without being limited to the display.
[0035]
【The invention's effect】
As described above, in the present invention, the linear motor actuator includes a motion guide device that guides the mover to move in the axial direction of the stator while supporting the load of the mover, and at least one end in the moving direction of the mover. And a bearing for suppressing the stator from bending so that the mover does not contact the stator. Therefore, even when the stator is long and the stroke of the mover is long, the mover can operate without contacting the stator.
[Brief description of the drawings]
FIG. 1 is a side view showing a linear motor actuator according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a rod and a mover.
FIG. 3 is a view (side view) showing the operation principle of the linear motor.
FIG. 4 is a diagram (front view) illustrating the operation principle of the linear motor.
FIG. 5 is a sectional view taken along a center line, showing the air bearing.
FIG. 6 is a cross-sectional view orthogonal to a center line showing the air bearing.
FIG. 7 is a perspective view showing an exercise guide device.
FIG. 8 is a side view showing a motion guide device (including a cross-sectional view partially along the longitudinal direction).
FIG. 9 is a front view showing another example of the exercise guide device.
[Explanation of symbols]
1: Base 3: Rod (stator)
4 mover 4b coil 7, 20 movement guide device 8 air bearing (bearing)
21: Track rail (track member)
22 Moving block (moving member)

Claims (6)

A rod-shaped stator having a field magnet, both ends of which are supported,
A mover having a coil fitted to the stator, and movable in an axial direction of the stator;
A movement guide device that guides the mover in the axial direction of the stator while supporting the load of the mover,
A bearing attached to at least one end of the moving direction of the mover, for suppressing the flexure of the stator so that the mover does not contact the stator,
A linear motor actuator comprising: 2. The linear motor actuator according to claim 1, wherein the bearing comprises an air bearing that blows compressed air between the stator and the bearing to support a load of the stator by air pressure. 3. The exercise guide device,
A track member extending elongated in parallel with the stator;
A moving member attached to the mover and movable along the track member;
The linear motor actuator according to claim 2, wherein compressed air is blown between the track member and the moving member, and the moving member is floated by air pressure. The compressed air blown between the stator and the bearing flows into a gap between the stator and the mover so that the mover can be cooled. 4. The linear motor actuator according to 3. With a base that is elongated,
A bar-shaped stator having a field magnet, both ends of which are supported by the base while extending in the longitudinal direction of the base,
A mover having a coil fitted to the stator, and movable in an axial direction of the stator;
A movement guide device disposed between the base and the mover, for guiding the mover in the axial direction of the stator while supporting the load of the mover,
An air bearing attached to at least one end in the moving direction of the mover,
A linear motor actuator comprising: The linear motor actuator according to any one of claims 1 to 5, wherein the bearing or the air bearing is attached to both ends of the mover in the moving direction.

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