JPH0556626A - Linear pulse motor - Google Patents

Abstract

PURPOSE:To eliminate a positioning error without enhancing processing and assembly accuracies of members by providing a plurality of driving coils for generating magnetic fluxes of the same polarity as that of a closed loop of a bias magnetic flux and moving a movable element at least two positions at the time of phase-exciting. CONSTITUTION:When a winding A is excited in a direction (a), a magnetic flux by a winding current is generated. The current flows in pole teeth 22-1, 22-1' in a direction for strengthening a bias magnetic flux by a permanent magnet 10, and reversely flows in pole teeth 22-3, 22-3' in a direction for weakening the bias magnetic flux by the magnet 10. As a result, the movable element pole teeth 14 of a movable element 6 are attracted to the teeth 22-1, 22-1', and the element 6 is stopped at a position opposed to the teeth 22-1, 22-1' to be stabilized. Then, when a winding B is excited in a direction (b), the teeth 14 of the element 6 is so similarly incrementally stepped by one step as to oppose to pole teeth 22-2, 22-2'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear pulse motor, for example, a linear pulse motor applied to a magnetic head drive system of a floppy disk drive in a word processor.

[0002]

2. Description of the Related Art As a conventional linear pulse motor, a guide member provided on a plane portion of a stator for guiding the sliding movement of a mover is positionally adjusted in parallel and at right angles to the plane portion of the stator. A member provided with a member is known (FIGS. 1 to 4 of JP-A-64-77461). The stator has four magnetic pole members each having magnetic pole teeth formed on the upper surface thereof, and iron cores extend from the lower surfaces of the four magnetic pole members, and bobbins are fitted around the respective iron cores. Each of these bobbins has a coil wound around them. Each of the four iron cores is magnetically connected to two yokes. Further, a permanent magnet is provided between these yokes. Further, the mover has two magnetic pole tooth rows formed on the lower surface (the surface facing the magnetic pole material of the stator). The tooth pitch and tooth width of the two magnetic pole tooth rows of the mover are the same as those of the magnetic pole teeth of the stator, but the one magnetic pole tooth row of the mover and the tooth of the other magnetic pole tooth row are shifted by 1/4 pitch. ..

Such a conventional linear pulse motor is
As can be seen from the description in JP-A-64-77461, the gap portion (gap formed by the bearing between the magnetic pole teeth of the mover and the magnetic pole teeth of the stator) that generates thrust is 1 for each phase.
It is arranged to be concentrated in one place.

[0004]

However, in the above-mentioned conventional linear pulse motor, the gap portion for generating thrust is arranged at one location for each phase. There was a problem. That is, (1) If the gaps of each phase are formed non-uniformly due to component / assembly errors, etc., a thrust force difference occurs between the phases, and thus the stiffness at each stable point increases or decreases, resulting in a positioning error. Was there. (2) If the component accuracy of the straightness in the longitudinal direction of the bearing and the flatness of the magnetic pole teeth of the mover is poor, gap variation occurs at each position of the mover, resulting in thrust difference, and positioning as in (1) above. There was an error. (3) Further, in order to make the gap uniform, it is necessary to enhance the processing accuracy and the assembly accuracy of the parts related to the gap formation, which increases the processing / assembly cost. (4) Further, additional work such as adjustment is required to obtain a uniform gap without performing high-level machining / assembly.

In view of the above-mentioned conventional problems, an object of the present invention is to obtain a uniform gap without increasing the machining / assembling precision of the members related to the gap formation such as the magnetic pole material and the bearing parts. It is an object of the present invention to provide a linear pulse motor having no thrust difference and therefore no positioning error, without requiring any additional work such as adjustment.

[0006]

A linear pulse motor of the present invention has a fixed portion having a plurality of magnetic pole teeth and a plurality of magnetic pole teeth facing the magnetic pole teeth of the fixed portion, and is movable to the fixed portion. In a linear pulse motor having a movable part attached to the fixed part, the fixed parts face each other (meaning that the surfaces face each other), and a closed loop of the bias magnetic flux is generated via the magnetic pole teeth of the fixed part and the magnetic pole teeth of the movable part. And a plurality of drive coils for moving the movable part by generating a magnetic flux having the same polarity as the closed loop of the bias magnetic flux at at least two points when exciting each phase in a predetermined order. It is characterized by having.

[0007]

In the linear pulse motor having the above structure, the permanent magnet provided in the fixed portion forms a closed loop magnetic path of the bias magnetic flux via the magnetic pole teeth of the fixed portion and the magnetic pole tooth of the movable portion which face each other. .. To move the movable part relative to the fixed part, each phase is excited in a predetermined order. When each phase is excited, the corresponding drive coil of the plurality of drive coils generates a magnetic flux having the same polarity as the closed loop of the bias magnetic flux at at least two locations to move the movable part.

In this way, the thrust force generated at the time of exciting each phase is not concentrated at one place as in the conventional case but is dispersed at at least two places. Therefore, the members related to the formation of the gap, such as the magnetic pole material and the bearing parts. It is possible to provide a linear pulse motor having no thrust difference and therefore no positioning error without increasing the machining / assembling accuracy of (1) and without requiring additional work such as adjustment for obtaining a uniform gap.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

2 is an exploded perspective view showing an embodiment of the linear pulse motor according to the present invention, FIG. 1 is a front sectional view showing an embodiment of the linear pulse motor of FIG. 2, and FIG. 3 is a linear pulse motor of FIG. 3 is an exploded perspective view of a part of the stator of FIG.

In these figures, the mover 6 is movable in the left-right direction (in the case of FIG. 2) via the ball 4 and the roller 5 supported by the retainer 3 on the reinforcing plate 2 to which the stator 1 is attached. Is becoming The stator 1 is a yoke 7,
The coil 8, the spacer 9, the permanent magnet 10 and the stator magnetic pole teeth 11 are assembled as shown in FIG. 4, which will be described later, and then fixed to the reinforcing plate 2. A V-shaped groove 12 is formed on the upper surface of the reinforcing plate 2, and the two balls 4 supporting the retainer 3 are fitted therein to define the moving direction of the retainer 3 with respect to the reinforcing plate 2. The fixing portion of the present invention includes a stator 1, a reinforcing plate 2, a base 15 and the like.

Further, the movable element 6 as the movable portion of the present invention.
Is composed of a mover body 13 and mover magnetic pole teeth 14. A V-shaped groove 15 is also formed on the lower surface of the mover body 13, and the ball 4 of the retainer 3 fits into the V-shaped groove 15. This fitting defines the moving direction of the mover 6 with respect to the retainer 3. The mover 6 is the V of the reinforcing plate 2.
It moves in a direction parallel to the groove 12. A mover magnetic pole tooth 14 facing the stator magnetic pole tooth 11 is attached to the lower surface of the mover body 13. All of the mover magnetic pole teeth 14 have the same pitch and the same phase. The reinforcing plate 2 is attached to a base 16, and the base 16 is attached to a device such as a floppy disk by screwing or the like.

FIG. 4 is an assembly view of the stator 1 which constitutes a part of the flat plate linear pulse motor shown in FIGS.
In FIG. 4, the stator 1 is composed of the four yokes 7, the coils 8, the spacers 9, the permanent magnets 10 and the stator magnetic pole teeth 11 as described above. As can be seen from FIG. 3, one yoke 7 has two convex portions 21, and the two yokes 7 sandwich the permanent magnet 10 as shown in FIG. Moreover, the yoke 7 and the permanent magnet 10 are adhered by an adhesive. Further, the spacer 9 is sandwiched by the two yokes 7 with the permanent magnet 10 sandwiched therebetween from both sides. Therefore, as shown in FIG. 3, the yoke 7, the permanent magnet 10, the yoke 7, the spacer 9, the yoke 7, and the permanent magnet 1 are provided.
0 and the yoke 7 are arranged. The coil 8 is fitted onto each of the convex portions 21 of the four yokes 7. In this case, as illustrated, the coil 8a is provided on the convex portions 21a and 21b, and the coil 8b and the convex portion 2 are provided on the convex portions 21c and 21d.
The coil 8c is externally fitted to 1e and 21f, and the coil 8d is externally fitted to the convex portions 21g and 21h.

As described above, in the stator 1, 8
A pole pole is formed. The stator magnetic pole teeth 11 are placed and fixed on the upper surface of the yoke 7 in which the coil 8 is fitted onto the convex portion 21. The stator magnetic pole teeth 11 are magnetic pole teeth 22 (22-1 to 22-4, 22-1 'to 22-4) formed by etching on eight positions facing each pole of the yoke 7 on the upper surface of the plate-shaped magnetic pole material. ′) Is formed. The stator magnetic pole tooth 11 is composed of eight magnetic pole teeth 22-1 to 22-4 and 22-1 'to 22-4'.
22-4 and 22-1 'to 22-4' all have the same pitch. Also, the magnetic pole teeth 22-1 and the magnetic pole teeth 22-1 ',
Magnetic pole tooth 22-2 and magnetic pole tooth 22-2 ', magnetic pole tooth 22-3 and magnetic pole tooth 22-3', magnetic pole tooth 22-4 and magnetic pole tooth 22-4 '.
Have the same phase, respectively. Also, the magnetic pole teeth 22-2
Are arranged with a 1/4 pitch phase shifted with respect to the magnetic pole teeth 22-1. The magnetic pole teeth 22-3 are arranged with a 1/2 pitch phase offset from the magnetic pole teeth 22-1. The magnetic pole teeth 22-4 are arranged with a 3/4 pitch phase shift with respect to the magnetic pole teeth 22-1.

Further, the permanent magnet 1 is passed from the permanent magnet 10 through the yoke 7, the magnetic pole teeth 22 of the stator magnetic pole teeth 11, the mover magnetic pole teeth 14, the magnetic pole teeth 22 of the stator magnetic pole teeth 11, and the yoke 7.
A closed loop magnetic path of the bias magnetic flux connecting 0 is formed. Therefore, each magnetic pole tooth 22 of the stator magnetic pole tooth 11 has a permanent magnet 1
Bias magnetic flux due to 0 flows. If the polarities of the permanent magnet 10 are as shown in the figure, the magnetic pole teeth 22-1, 22-3, 2
2-4 and 22-2 are north poles, and the magnetic pole teeth 22-1 ', 22-3', 22-4 'and 22-2' are south poles.

By reversing the polarity arrangement of one of the permanent magnets 10, the magnetic pole teeth 22-1, 22-3, 22 are arranged.
-4 'and 22-2' are N poles, magnetic pole teeth 22-1 ', 2
2-3 ', 22-4, and 22-2 may be south poles.

Next, the operation will be described with reference to FIGS. 5 and 6. FIG. 5 is a top view of the stator that constitutes the linear pulse motor according to the present invention, and particularly shows the polarities of the permanent magnets 10 arranged in the winding direction. In FIG.
The winding is wound in two-phase bipolar. That is, the winding A is formed by winding the magnetic pole teeth 22-3 'and the magnetic pole teeth 22-1 in the counterclockwise direction and then winding the magnetic pole teeth 22-3 and the magnetic pole teeth 22-1' in the counterclockwise direction. Has become. The winding B has a shape in which the magnetic pole teeth 22-4 and the magnetic pole teeth 22-2 'are wound in the clockwise direction and then the magnetic pole teeth 22-2 and the magnetic pole teeth 22-4' are wound in the clockwise direction. ing. FIG. 6 is a simplified diagram for explaining the operating principle of the linear pulse motor of FIG.
6A to 6D are cross-sectional views taken along the lines AA, BB, CC and DD of FIG. 1, respectively.

First, when the winding A is energized in the direction of a, a magnetic flux is generated by the winding current. In the direction, the magnetic pole teeth 22-1 and the magnetic pole teeth 22-1 'flow in a direction in which the bias magnetic flux of the permanent magnet 10 is strengthened, and the magnetic pole teeth 22-3 and the magnetic pole teeth 22-1.
On the other hand, at −3 ′, the bias magnetic flux from the permanent magnet 10 flows in the opposite direction. As a result, the mover magnetic pole teeth 1 of the mover 6
4 is attracted to the magnetic pole teeth 22-1 and the magnetic pole teeth 22-1 ', and faces the magnetic pole teeth 22-1 and the magnetic pole teeth 22-1' as shown in FIGS. The faces are opposite)
At such a position, the mover 6 stops and becomes stable.

Next, when the winding B is energized in the direction of b, in the same manner, in the magnetic pole teeth 22-2 and the magnetic pole teeth 22-2 ', the bias magnetic flux generated by the permanent magnet 10 is strengthened by the generated magnetic flux, and the magnetic poles are generated. On the contrary, the tooth 22-4 and the magnetic pole tooth 22-4 'are weakened by the magnetic flux generated by the bias magnetic flux of the permanent magnet 10. As a result, the mover magnetic pole teeth 1 of the mover 6
The mover 6 advances one step from the position shown in FIG. 6 so that 4 faces the magnetic pole teeth 22-2 and the magnetic pole teeth 22-2 '.

Thereafter, by sequentially energizing the windings A and B in the direction of c → d → a, the mover 6 performs a stepping operation.

When the mover 6 is operated in the opposite direction, the order of energizing the windings A and B is d → c → b → a → d.
And it is sufficient.

FIG. 7 is an explanatory view showing the distribution of the attraction force between the stator and the mover in the embodiment of the present invention and the conventional example. FIG. 1A is a distribution diagram showing the distribution of the attraction force between the stator and the mover in the conventional example. FIG. 6B is a distribution diagram showing the distribution of the attraction force between the stator and the mover in the embodiment of the present invention, showing the stator 1 when the winding A is energized in the a direction in FIG. Attraction force between mover 6 (stator pole teeth 1
1 shows the distribution of the attraction force acting between 1 and the mover magnetic pole teeth 14. Numerical values in FIGS. 7A and 7B represent the magnitude of the suction force (force acting in the direction perpendicular to the moving direction of the mover 6).

In the present invention, the attraction force between the stator and the mover is dispersed in a better balance than in the conventional case, as can be seen from FIG. Moreover, in the present invention, the magnetic pole of the stator 1 is set to 8
The thrust generated during each phase excitation is 1
7 (A in the case of FIG. 7A) is not concentrated, but at two points (for example, when the winding A is energized in the direction of a in FIG. 5, the magnetic pole teeth 22-1, 22-1 'on the position (corresponding to two positions of the numerical value "5" in FIG. 7B))
The following effects can be obtained because the configuration is such that That is, (1) even if the gap is not uniform due to part / assembly error,
Canceled between the phases distributed in several places,
There is no difference in thrust, so there is no difference in stiffness at each stable point. Therefore, when the mover 6 is moved, no positioning error occurs. (2) Even if the gap becomes uneven at each position of the mover 6, the thrust difference does not occur for the same reason as the above (1). Therefore, when the mover 6 is moved, no positioning error occurs. (3) Since there is no difference in thrust force from the above (1), uneven feeding of microsteps does not occur. (4) According to the above (1) and (2), even if there is a machining / assembling error in the parts related to the gap formation, a thrust difference does not occur, so that it is not necessary to perform highly accurate machining / assembling as in the prior art. (5) Because of the reason (1) above, there is no need for additional work such as adjustment for obtaining a uniform gap in the parts that have processing / assembly errors. (6) Since the magnetic flux required to obtain the same thrust as the conventional one is dispersed in several places, the cross-sectional area of the required magnetic path of the mover 6 becomes small, and the mover 6 can be made thinner (lighter). Therefore, it is possible to realize high speed by reducing inertia. (7) Permanent magnet 10 required to obtain the same thrust as the conventional one
Since the magnetic path of the magnetic flux of is half that of the conventional one,
The magnetomotive force loss in the iron part is reduced, and the permanent magnet 10 can be downsized.

The present invention is not limited to this embodiment, and various applications and modifications are conceivable without departing from the gist of the present invention.

[0025]

As described above, according to the present invention, the fixed portion has a plurality of magnetic poles, and the thrust generated at each phase excitation is 1
The following effects can be obtained because the points are not concentrated but dispersed in at least two points. (1) Even if gaps become uneven due to parts / assembly errors,
Canceled between the phases distributed in several places,
No thrust difference is produced. Therefore, when moving the movable part,
Positioning error does not occur. (2) Even if the gap becomes uneven at each position of the movable portion, the thrust difference does not occur for the same reason as the above (1). Therefore, when moving the movable part, no positioning error occurs. (3) According to the above (1) and (2), even if there is a machining / assembling error in the parts related to the gap formation, a thrust difference does not occur, so that highly accurate machining / assembling as in the conventional case is unnecessary. (4) Because of the reason (1) above, there is no need for additional work such as adjustment to obtain a uniform gap in the parts that have processing / assembly errors. (5) Since the magnetic flux required to obtain the same thrust as the conventional one is dispersed at several places, the cross-sectional area of the required magnetic path of the movable part becomes small, and the movable part can be made thinner (lighter). Higher speed can be realized by reducing inertia. (6) Since the magnetic path of the bias magnetic flux due to the permanent magnet of the fixed part required to obtain the same thrust as the conventional one is 1/2 that of the conventional one, the magnetomotive force loss in the iron part is reduced and the fixed part The permanent magnet can be miniaturized.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the linear pulse motor of FIG.

FIG. 2 is an exploded perspective view showing an embodiment of a linear pulse motor according to the present invention.

FIG. 3 is an exploded perspective view of a part of a stator of the linear pulse motor of FIG.

FIG. 4 is an assembly diagram of a stator 1 which constitutes a part of the flat plate linear pulse motor of FIGS. 1 and 2.

FIG. 5 is a top view of a stator constituting a linear pulse motor according to the present invention.

FIG. 6 is a simplified diagram illustrating the operating principle of the linear pulse motor of FIG.

FIG. 7 is an explanatory diagram showing the distribution of the attraction force between the stator and the mover in the example of the present invention and the conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Stator 2 Reinforcement plate 6 Mover 7 Yoke 8 Coil 9 Spacer 10 Permanent magnet 11 Stator magnetic pole tooth 14 Mover magnetic pole tooth 16 Base 22, 22-1 to 22-4, 22-1 'to 22-4'
Magnetic pole teeth

Claims (1)

[Claims] 1. A linear unit having a fixed portion having a plurality of magnetic pole teeth, and a movable portion having a plurality of magnetic pole teeth facing the magnetic pole teeth of the fixed portion and movably attached to the fixed portion. In the pulse motor, the fixed portion includes a permanent magnet that forms a closed loop magnetic path of a bias magnetic flux via magnetic pole teeth of the fixed portion and magnetic pole teeth of the movable portion that face each other, and each phase in a predetermined order. A linear pulse motor comprising: a plurality of drive coils for generating a magnetic flux having the same polarity as the closed loop of the bias magnetic flux at the time of excitation to move the movable portion.