JPH03207256A - Linear servo motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a linear servo motor suitable for use in precision positioning, high-speed conveyance, and the like.

[Conventional technology] Among linear motors that are applied in various industrial fields, linear servo motors that use permanent magnets in the field have excellent servo characteristics for positioning performance and speed performance, so they can be used for precision Used for positioning, high-speed conveyance, etc.

FIG. 5 is a sectional view of a conventional linear servo motor, and FIG. 6 is a top view of the field core of the linear servo motor. In these figures, l is a field iron core, on which a plurality of field permanent magnets 2 are arranged so that N poles and S poles alternate at regular intervals. In addition, these permanent magnets 2 are
They have a skew structure in which they are arranged diagonally so that the spatial distribution of the field magnetic flux they generate becomes a sine wave. Reference numeral 3 denotes an armature core arranged with a gap between it and the field core 1, and a plurality of slots 3a provided at the bottom of the armature core 3.
A coil 4 is wound around each of them. by the way,
The field magnetic flux φ generated from the permanent magnet 2 reaches the armature core 3 through the air gap, as shown by the broken line in FIG. Then, it passes through the field core l and returns to the original permanent magnet 2. A magnetic flux path interlinking with the coil 4 is formed by this field MIFiFI flux φ, and an induced voltage is generated in the coil 4 due to the movement of the armature core 3.

Furthermore, a detector (such as a Hall element), not shown, is attached to the armature core 3 to detect the field magnetic flux φ.

Reference numeral 5 denotes a control circuit that performs speed control, position control, etc. of the armature core 3, which receives a detection signal from the self-detector and supplies a control signal to the driver 6 based on this input signal. Then, in accordance with this control signal, the driver 6 applies a drive current that is in phase with the above-mentioned induced voltage to the coil 4 through the conductor 7 and the brush 8.
supply to. The coil 4 generates magnetic flux according to the supplied drive current. Thrust is generated in the armature core 3 due to the interaction between the magnetic flux generated by the coil 4 and the field magnetic flux φ generated by the permanent magnet 2, and the armature core 3 is driven in one of the directions shown by the arrows. .

[Problem to be solved by the invention 1 By the way, the driving principle of a linear servo motor is the same as that of a general permanent magnet type AC servo morph, and for a linear servo motor, it is important to suppress speed fluctuations and thrust fluctuations as much as possible. is an important matter that determines the quality of motor characteristics. In order to suppress this thrust variation, the spatial distribution of the field magnetic flux is made into a sine wave, and the induced voltage is made into a sine wave.
It is necessary to make the generated thrust a smooth constant value.

However, in a linear servo motor, the field magnetic flux is generated by a permanent magnet, so the spatial magnetic flux distribution becomes closer to a rectangular wave than a sine wave.

Therefore, in the past, as shown in Figure 6, permanent magnets were arranged diagonally in a skew structure, or the slots in the field core were made in a skew structure to bring the induced voltage closer to a sine wave, but these efforts were not effective enough. I couldn't.

The present invention has been made in view of the above problem, and an object of the present invention is to provide a linear servo motor with excellent motor characteristics in which the spatial distribution of field magnetic flux is made into a sine wave.

[Means for Solving the Problems] In order to achieve the above object, the present invention generates a field magnetic flux by a plurality of permanent magnets arranged on one side of a field core, and generates a field magnetic flux that is wound around an armature core. In a linear servo motor that generates a magnetic flux that interacts with the field magnetic flux by a coil and moves the armature core in a straight line, the longitudinal cross-sectional shape of the permanent magnet has two parallel arcs, two parallel elliptical arcs, or two parallel elliptical arcs. The enclosure, which is defined by parts of two parallel hyperbolas and faces the field core of the armature core, is provided with protrusions at equal intervals in the longitudinal direction, with which the inner circumferential surface of the permanent magnet can be aligned. The inner peripheral surface of the permanent magnet is aligned with the inner peripheral surface of the permanent magnet.

[Function] In this invention, since the cross-sectional shape of the permanent magnet is defined by a part of two parallel arcs, elliptical arcs, or hyperbolas, the gap length between the field core and the permanent magnet is equal to the center of the permanent magnet. The permeance of the magnetic circuit is highest at the center of the permanent magnet, and the permeance of the magnetic circuit is highest at the center of the permanent magnet, and the permeance is the longest at the center of the permanent magnet. It becomes lower as the number increases, and is the lowest among adjacent permanent magnets.

From the perspective of the permanent magnet, it can be seen that the operating point of each part of the permanent magnet gradually becomes lower as it moves away from the pole center, and the amount of magnetic flux generated by the permanent magnet decreases. Therefore, The spatial distribution of the field magnetic flux approaches a sine wave, and the thrust force generated by the field core becomes a smooth constant value.

[Embodiment 1] Next, an explanation will be given of the implementation of the present invention with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a first embodiment of the present invention. In this figure, parts corresponding to those of the conventional example shown in FIG.

In this figure, 10 is a field iron core, which is composed of a plurality of electric iron plates 10a, 10a, . . . shown in FIG. On one longitudinal side of the electric iron plate 10a, circular arc-shaped protrusions 11 are provided at regular intervals by punching or the like, and by stacking the electric iron plates in the same direction, the field iron core 10 is formed. It is formed. Further, by stacking the layers as described above, the upper part of the field core 10 has arc-shaped protrusions 11, 11, . -... will be formed at regular intervals. On the other hand, as shown in FIG. 2, the permanent magnet 13 has a longitudinal cross-sectional shape defined by two parallel circular arcs, and its inner peripheral surface 13a is aligned with the protrusion 11 of the field core 10. The permanent magnet 13 is arranged so that the magnetic poles appearing on the upper part of the permanent magnet 13 alternate with north poles and south poles.

In this way, by providing the field core 10 with the permanent magnet 13 whose cross-sectional shape is defined by two parallel arcs,
The permeance (reciprocal of magnetic resistance) of the air gap between the field core 10 and the armature core 3 is not constant, but has a predetermined spatial distribution.

That is, the permeance of the air gap is highest at the center of the magnetic pole and lowest at the magnetic pole switching point, as shown by the solid line in FIG. 3, and the distribution of the field magnetic flux Φ approaches a sine wave from a rectangular wave. (The dashed line in FIG. 3 shows the distribution of field magnetic flux Φ of the conventional linear servo motor shown in FIG. 5.) Therefore, the armature core 3 is driven by the drive current supplied from the driver 6. Drives smoothly.

Next, FIG. 4 shows a sectional view of a linear servo motor according to a second embodiment of the present invention. This embodiment is completely the same as the first embodiment except that the protrusion 11 of the field core IO is elliptical and the longitudinal cross-sectional shape of the permanent magnet 13 is defined by two parallel elliptical arcs. In this example, as in the example shown in FIG.
The distribution approaches a sine wave. Therefore, the armature core 3 is smoothly driven by the drive current supplied from the driver 6.

Note that the shape of the permanent magnets 13 is not limited to the one described above, and the gap length between the armature core and the permanent magnets is longest at the center of each permanent magnet and becomes shorter toward the ends. The permanent magnet may be shaped so that its longitudinal cross-sectional shape is defined by parts of two parallel hyperbolas, and the projections may be formed to align with the inner surface of the permanent magnet. In other words, the permeance distribution is highest at the magnetic pole center and lowest at the magnetic pole switching point, so that spatial harmonics are minimized in correlation with the motor air gap length.

〔Effect of the invention〕

As explained above, the present invention uses a permanent magnet whose longitudinal cross-sectional shape is defined by a part of two parallel circular arcs, elliptical arcs, or hyperbolas, and the inner circumferential surface of this permanent magnet is attached to the field core. Since the permeance distribution of the air gap is the highest at the magnetic pole center of the permanent magnet and the lowest at the magnetic pole switching point, the spatial distribution of the field M1 magnetic flux can be made closer to the sine wave. can. As a result, the generated thrust can be made constant, and a linear servo motor with excellent characteristics can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a first embodiment of the present invention;
Fig. 2 is a perspective view showing the structure of the field core and permanent magnet of the same embodiment, and Fig. 3 is a field Fi generated by the permanent magnet of the same embodiment.
A magnetic flux density curve diagram showing the Ii magnetic flux, FIG. 4 is the second diagram of the same invention.
FIG. 5 is a cross-sectional view of a conventional linear servo motor, and FIG. 6 is a top view of the field core of the linear servo motor. 3... Armature core, 10... Field core, 11--Protrusion, 13... Permanent magnet.

Claims (1)

[Claims] A field magnetic flux is generated by a plurality of permanent magnets arranged on one side of the field core, and a magnetic flux that interacts with the field magnetic flux is generated by a coil wound around the armature core. In the linear servo motor for linear movement, the longitudinal cross-sectional shape of the permanent magnet is defined by parts of two parallel arcs, two parallel elliptical arcs, or two parallel hyperbolas, and the armature core of the field core A linear servo characterized in that protrusions are provided at equal intervals in the longitudinal direction on a surface facing the permanent magnet so that the inner circumferential surface of the permanent magnet can be aligned, and the protrusions and the inner circumferential surface of the permanent magnet are aligned. motor.