JP4798698B2 - Cylindrical linear motor - Google Patents

Description

  The present invention relates to a cylindrical linear motor with a built-in vibration damping function.

  Japanese Patent Laid-Open No. 2001-23894 describes a configuration using a cylindrical linear motor as a drive source for a stage of an exposure apparatus used in a semiconductor element manufacturing process. This cylindrical linear motor is also referred to as a shaft motor, and a large number of permanent magnets are arranged in a straight line in a cylindrical shaft, and a mover with a coil incorporated outside the shaft is concentric with the shaft. It arrange | positions and it is comprised so that a needle | mover may be linearly driven along a shaft by supplying with electricity to a coil. This cylindrical linear motor is used as a drive source for a linear motor car in that it generates thrust to drive the mover with the attraction / repulsion force between the magnetic field generated by energizing the coil and the magnetic field of the permanent magnet. The thrust generation principle is the same as that of the flat type linear motor, but the cylindrical type linear motor has a coreless structure without an iron core, and the coil of the mover completely surrounds the outer periphery of the permanent magnet. Compared with the flat plate type linear motor, the magnetic flux utilization efficiency of the permanent magnet is high, the electric power supplied to the coil can be efficiently converted into thrust, enabling high-speed driving, and cogging does not occur due to the coreless structure. There is an excellent feature that the speed unevenness is very small.

  On the other hand, in the cylindrical linear motor, the reaction force at the time of driving the mover acts directly on the shaft containing the permanent magnet. Therefore, the shaft is vibrated and the base side is vibrated via the bracket that supports the shaft. This vibration causes a decrease in the positioning accuracy of the mover.

Therefore, in Patent Document 1, in order to reduce the influence of vibration generated on the shaft due to the reaction force at the time of driving the mover (stage), the support member that supports the shaft of the cylindrical linear motor is replaced with the mover (stage). It is configured to be completely independent (separated) from a base member that is slidably supported.
Japanese Patent Laid-Open No. 2001-23894 (page 3, etc.)

  However, if the support member that supports the shaft of the cylindrical linear motor is configured to be completely independent (separated) from the base member that slidably supports the mover as in Patent Document 1, the shaft and the mover The positional relationship between the shaft and the mover is a problem when mounting this cylindrical linear motor on the device. Unless the problem is solved, practical use seems to be difficult.

  In order to reduce the influence of machine vibration, a vibration suppression filter that removes vibration components that induce machine vibration from the motor control signal may be provided. However, in this configuration, a response delay is caused by the vibration suppression filter. Therefore, it has been regarded as a problem to deteriorate the responsiveness of the high-speed positioning operation.

  As another measure to suppress machine vibration, an electronic control damper device can be installed in the support mechanism that supports the cylindrical linear motor, and the machine vibration can be suppressed by electronic active control using the electronic control damper device. However, there is a problem that the apparatus is increased in size, increased in cost, and complicated in the control system.

  The present invention has been made in view of these circumstances. Therefore, the object of the present invention is to provide a movable element for the cylindrical linear motor itself without taking measures against vibrations in the apparatus or control system on which the cylindrical linear motor is mounted. An object of the present invention is to provide a cylindrical linear motor capable of having a function of reducing the influence of vibration generated by a reaction force during driving.

In order to achieve the above object, according to the first aspect of the present invention, a plurality of permanent magnets are arranged in a straight line in a cylindrical shaft, and a mover incorporating a coil is arranged outside the shaft. In a cylindrical linear motor that linearly drives the mover along the shaft by energizing the coil, the plurality of permanent magnets are accommodated in the shaft so that each permanent magnet can independently vibrate. In addition, a vibration attenuating means for attenuating the vibration of each permanent magnet generated by the reaction force at the time of driving the mover is provided. In this configuration, the vibration of each permanent magnet generated by the reaction force at the time of driving the mover is attenuated by the vibration damping means in the shaft, so that the cylindrical linear motor itself can have a vibration reducing function, It is possible to reduce the size and cost of the equipment equipped with the cylindrical linear motor, simplify the control system, and eliminate the need for conventional vibration countermeasures for the equipment and control system equipped with the cylindrical linear motor. It can cope with high-accuracy and high-speed positioning operation without the problem of response delay due to the conventional vibration damping filter.

  In this case, as a preferred embodiment of the vibration attenuating means, for example, as in claim 2, a vibration attenuating member for attenuating the vibration of each permanent magnet is sandwiched between each permanent magnet, or According to a third aspect of the present invention, the viscous fluid is filled in the shaft and the vibration of each permanent magnet is attenuated by the viscous resistance of the viscous fluid filled between the permanent magnets, or The end surfaces where the permanent magnets contact each other are formed on the inclined surface as in claim 4 so that the vibration of each permanent magnet is attenuated by the frictional resistance force when the permanent magnet vibrates along the inclined surface. You may comprise. Whichever configuration is employed, the vibration of each permanent magnet generated by the reaction force during driving of the mover can be attenuated in the shaft.

  Hereinafter, four Examples 1 to 4 embodying the best mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the cylindrical linear motor 11 (shaft motor) has a large number of permanent magnets 13 arranged in a straight line in a cylindrical shaft 12 and a coil 14 on the outside of the shaft 12. The movable element 15 having a built-in is arranged concentrically with the shaft 12, and the movable element 15 is linearly driven along the shaft 12 by energizing the coil 12. A vibration damping member 18 is sandwiched between the permanent magnets 13 in the shaft 12. Each permanent magnet 13 in the shaft 12 is arranged so that the south poles and the north poles of the adjacent permanent magnets 13 face each other. The shaft 12 is formed of a pipe made of a nonmagnetic material (for example, stainless steel) that transmits the magnetic flux of each permanent magnet 13. The coil 14 of the mover 15 is disposed concentrically with the shaft 12 so as to surround the outer periphery of the shaft 12 (permanent magnet 13). Both ends of the shaft 12 are horizontally fixed to a support bracket 17 erected on the machine base 16.

  As shown in FIGS. 2 and 3, a vibration damping member 18 is sandwiched between the permanent magnets 13 in the shaft 12 as vibration damping means. The vibration damping member 18 is made of an elastically deformable or plastically deformable material, and more preferably a viscoelastic body having excellent vibration absorption characteristics such as a damping rubber. In this case, the shaft 12 plays a role of accommodating each permanent magnet 13 and positioning in the radial direction. However, each permanent magnet 13 is not fixed in the axial direction with respect to the shaft 12, Thus, the permanent magnets 13 can independently vibrate in the axial direction, and the interval between the permanent magnets 13 is held by the vibration damping member 18.

  In the cylindrical linear motor 11 according to the first embodiment configured as described above, the vibration damping member 18 is sandwiched between the permanent magnets 13 in the shaft 12. The generated vibration of each permanent magnet 13 is damped by the vibration damping member 18 in the shaft 12 and, as a result, is transmitted from the shaft 12 to the machine base 16 via the support bracket 17 by the reaction force when the mover 15 is driven. Vibration is reduced.

  As described above, the cylindrical linear motor 11 according to the first embodiment has a configuration in which the vibration reducing function is compactly incorporated in the cylindrical linear motor 11 itself. Even if the conventional vibration countermeasure is not applied to the system, the vibration due to the reaction force at the time of driving the mover 15 can be reduced inside the cylindrical linear motor 11, and the apparatus equipped with the cylindrical linear motor 11 can be reduced. It is possible to realize downsizing, cost reduction, and simplification of the control system, and it is possible to cope with high-accuracy high-speed positioning operation without the problem of response delay due to the conventional vibration damping filter.

  Note that a slide guide for guiding the slide of the mover 15 (or a slide member attached to the mover 15) may be provided in the machine base 16. Even in this case, due to the reaction force when the mover 15 is driven. Since the generated vibration of each permanent magnet 13 is damped by the vibration damping member 18 in the shaft 12, the problem of vibration transmission to the slide guide does not occur.

  In the second embodiment of the present invention shown in FIG. 4, a viscous damper is used as a vibration attenuating means for attenuating the vibration of each permanent magnet 13 generated by the reaction force when the mover 15 is driven. This viscous damper is configured to attenuate the vibration of each permanent magnet 13 by the viscous resistance force of the viscous fluid 21 filled in the shaft 12 with the viscous fluid 21 filled between the permanent magnets 13. . As the viscous fluid 21, grease or the like having excellent viscosity characteristics in the fine movement region may be used. Each permanent magnet 13 is formed with one or a plurality of small-diameter through holes 22 through which the viscous fluid 21 is circulated in the axial direction, and vibration damping characteristics depend on the diameter of each through-hole 22 and the viscosity of the viscous fluid 21. Adjusted. Other configurations are the same as those of the first embodiment.

  In the second embodiment described above, the vibration of each permanent magnet 13 is attenuated by the viscous resistance force of the viscous fluid 21 filled in the shaft 12 and filled between the permanent magnets 13. Therefore, the vibration of each permanent magnet 13 generated by the reaction force during driving of the mover 15 can be attenuated by the viscous resistance force of the viscous fluid 21, and the same effect as in the first embodiment can be obtained. Obtainable.

  In the third embodiment of the present invention shown in FIG. 5, a spring 25 such as a coil spring is used as a vibration attenuating means for attenuating the vibration of each permanent magnet 13 generated by the reaction force when the mover 15 is driven. A spring 25 is sandwiched between the permanent magnets 13. In this case, the vibration damping characteristic is adjusted by adjusting the elastic coefficient of the spring 25. Other configurations are the same as those of the first embodiment.

  In the third embodiment, the vibration of each permanent magnet 13 generated by the reaction force during driving of the mover 15 can be attenuated by the elastic force of the spring 25, and the same effect as in the first embodiment can be obtained. it can.

  The third embodiment may be implemented in combination with the second embodiment. In other words, the spring 25 is sandwiched between the permanent magnets 13 in the shaft 12, the viscous fluid is filled in the shaft 12, and the vibrations of the permanent magnets 13 generated by the reaction force when the mover 15 is driven are detected. You may make it attenuate | damp with the elastic force of the spring 25, and the viscous resistance force of a viscous fluid.

  In the fourth embodiment of the present invention shown in FIG. 6, a friction damper is used as a vibration attenuating means for attenuating the vibration of each permanent magnet 13 generated by the reaction force when the mover 15 is driven. In this friction damper, the end surfaces where the permanent magnets 13 in the shaft 12 contact each other are formed on inclined surfaces, and the vibrations of the permanent magnets 13 are caused by the frictional resistance when the permanent magnets 13 vibrate along the inclined surfaces. Is configured to attenuate. In this case, the vibration damping characteristic is adjusted by adjusting the friction coefficient of the inclined surface (contact surface) of each permanent magnet 13. A member having an appropriate friction coefficient may be laminated on the inclined surface (contact surface) of each permanent magnet 13, or the inclined surface (contact surface) of each permanent magnet 13 may be roughened to obtain a surface roughness (friction). The coefficient may be adjusted.

  A support material 27 is provided on the inner peripheral surface of the shaft 12 to hold the permanent magnets 13 so that they can vibrate. The support member 27 is formed of the same kind of elastically deformable or plastically deformable material as the vibration damping member 18 of the first embodiment. Alternatively, the same kind of viscous fluid as the viscous fluid 21 of the second embodiment may be used as the support material 27. Other configurations are the same as those of the first embodiment.

  In the fourth embodiment described above, the end surfaces where the permanent magnets 13 in the shaft 12 come into contact with each other are formed on the inclined surfaces, and each permanent magnet 13 is caused by the frictional resistance when the permanent magnets 13 vibrate along the inclined surfaces. Since the vibration of the permanent magnet 13 is configured to be attenuated, the same effect as in the first embodiment can be obtained.

It is a figure which shows roughly the apparatus carrying the cylindrical linear motor of Example 1 of this invention. It is a perspective view of the principal part of the cylindrical linear motor of Example 1. 1 is a cross-sectional view of a main part of a cylindrical linear motor according to Embodiment 1. FIG. It is sectional drawing of the principal part of the cylindrical linear motor of Example 2. FIG. It is sectional drawing of the principal part of the cylindrical linear motor of Example 3. It is sectional drawing of the principal part of the cylindrical linear motor of Example 4.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Cylindrical linear motor, 12 ... Shaft, 13 ... Permanent magnet, 14 ... Coil, 15 ... Mover, 16 ... Machine stand, 17 ... Support bracket, 18 ... Vibration damping member (vibration damping means), 21 ... Viscous flow Body (vibration damping means), 22 ... through hole, 25 ... spring (vibration damping means), 27 ... support material

Claims (4)

A plurality of permanent magnets are arranged in a straight line in a cylindrical shaft, and a mover containing a coil is arranged on the outside of the shaft concentrically with the shaft, and the movable coil is energized by energizing the coil. In a cylindrical linear motor that drives the child linearly along the shaft,
A vibration that accommodates the plurality of permanent magnets in the shaft so that the permanent magnets can independently vibrate, and attenuates the vibration of the permanent magnets generated by a reaction force when the mover is driven. A cylindrical linear motor provided with a damping means.   2. The cylindrical linear motor according to claim 1, wherein the vibration attenuating means is configured by sandwiching a vibration attenuating member for attenuating vibrations of the permanent magnets between the permanent magnets.   The vibration damping means is configured to attenuate the vibration of each permanent magnet by the viscous resistance force of the viscous fluid filled between the permanent magnets by filling the shaft with a viscous fluid. The cylindrical linear motor according to claim 1.   The vibration attenuating means attenuates the vibrations of the permanent magnets by a frictional resistance force when the permanent magnets vibrate along the inclined surface by forming end surfaces where the permanent magnets contact each other on the inclined surface. The cylindrical linear motor according to claim 1, wherein the cylindrical linear motor is configured as described above.

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