JPS59156146A - Dc motor including permanent magnet type stator - 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 The present invention relates to a permanent magnet commutator type, C., a stator for a servo motor, and, in particular, to such a stator.

The present invention relates to a stator that has an optimal interpole region for improving the torque performance of a servo motor.

Most permanent magnet servo motors include a stator formed from a tube with attached permanent magnets in various ways. The tube in such servo motors usually consists of a cylindrical body with a substantially uniform wall thickness. The permanent magnets used in multiples of 2 are arranged symmetrically about the pole center line and are fixed in place by mechanical means such as a clamping mechanism or by adhesive.The thickness of the two permanent magnets, i.e. the radius of the pole center line. The dimensions are determined according to the magnetic material to maintain sufficient magnetic saturation in the magnetic circuit of the servo motor. The magnetic tubes which together with the permanent magnets form the stator are generally constructed in one piece or even from a stack of coaxial disks.

Recent technological advances have required high motor torque for this type of motor as well. Attempts to date to improve this high torque motor performance have been only partially successful. The focus of these improvements was to make the magnets stronger and thinner.

Therefore, the result was to reduce the interpole spacing between the yoke seven and the armature seven. This leads to an increase in leakage flux between the poles, thus inducing voltage in the commutating armature coil, causing excessive sparking in the brushes and commutator flashover. There is a danger. This leakage flux is an effect of armature reaction. Furthermore, in some regions of the stator, the armature field opposes the stator magnetic flux, and in other regions, the armature field or the stator magnetic field adds to the stator magnetic flux. The overall effect is to reduce the total stator flux due to magnetic saturation.

The above problems occur most noticeably when rare earth M<RE CO5) magnets with an energy product of 18 MGo are used in the stator in combination with a conventional wound iron core armature. These rare earth magnets have high resistance to magnetic reversal. A permanent magnet commutator type using these rare earth magnets can be used instead of a normal wire-wound iron core armature in order to quickly accelerate or decelerate in a C servo motor without sacrificing performance. Is it necessary to use an expensive cup-shaped armature? Typical examples of permanent magnet motors with cup-shaped armatures are e.g.
No. 3,102,964 to Kat et al. These J-shaped armatures are relatively difficult to manufacture and increase the motor cost I to a considerable extent.

Therefore, in this field, low 1i11i 1&
A technique for quickly accelerating and decelerating a permanent magnet commutator type C servo motor with a conventional wound iron core armature without sacrificing its performance.
is required.

The device of the present invention uses a permanent magnet commutator using a strong magnet and a conventional wire-wound iron core armature.

C. Provides a servo motor. High-strength magnets, preferably containing rare earth elements, are fixed to a cylindrical stator with stepped interpolar regions.

These stepped interpolar regions limit the magnetic flux from the permanent magnet poles to increase their effective strength and improve motor performance.

In the present invention, the effect of armature reaction flux in the region between stator poles can be reduced, and high torque performance and commutation characteristics can be significantly improved compared to conventional servo motors with wound iron core armatures. It's been found. This is because it increases the non-magnetic interpolar region. Torque to amps at high torques is improved. Also, −
The distortion of the secondary stator flux is reduced and the torque is improved. - The secondary flux is improved in the armature current. Furthermore, by grading the interpole area at both ends of the permanent magnet to a depth that is a predetermined ratio to other important magnet dimensions of the stator, maximum performance can be extracted from the servo motor for a given size. can.

This is achieved by maintaining constant the sum of the length of the permanent magnet pole and the thickness of the annular yoke and the ratio of the depth of the interpole stage to the inner diameter of the pole piece.

The invention will be best understood from the following description with reference to the accompanying drawings.

Referring to FIG. 1, a stator for a permanent magnet, C, servo motor is shown in practical size from one end of its core; This yoke (2) has arcuate portions (4) and (6) made of a magnetic material such as soft iron formed at equal intervals on its inside. Arc-shaped permanent magnets (8) and (10) each made of a rare earth element, ie, a rare earth element, or other high-strength permanent magnet material, are fixed to the inner surface. These permanent magnets preferably consist of rare earth cobalt magnets with an energy product of 18λri co.

The arcuate members (4), (6) are fixed to the inner surface of the yoke (2) by screws, bolts or adhesives, or alternatively are provided as integrally formed parts of the yoke (2).

The yoke (2) itself can be formed from an integral cylinder, but it is preferable that the yoke (2) and the arc-shaped parts (4) and '<6> are stamped and the stamped body is formed by stamping. They are finished in a cylindrical shape by stacking them on top of each other and binding them together with welds or bolts or other structural fixing means. Of course, whatever method is used to bind these together, it must not impair the magnetic properties of this layered structure.

The stator core of FIG. 1 is applied to a servo motor having an armature that rotates clockwise. The armature magnetic field in such a servo motor is B
In the stator region, the direction is opposite to the stator magnetic flux, and the direction is added to the stator magnetic flux at the part A on the stator core, which is also surrounded by a dashed line.

As mentioned above, the performance of the permanent magnet servo motor of the present invention is determined by the relationship between the radial thickness of the seed portion of the permanent magnet stator element and the relationship with the inner diameter of the stator core. This can be maximized by setting a constant ratio of . The stator of FIG. 1 as described above is drawn substantially at its realistic size. The permanent magnet stator has an outer diameter of 133. ,．． 4mm (5,25')
The servo motor also has a conventional wire-wound iron core armature with an outer diameter of 74°9 mm (2,95"). Contains. The motor is also O',
76mm (1.

13"), thereby providing a gap of 7' 6,45
Provides an internal diameter of mm (3,01").

As is clear from FIG. 1, the radial thickness 12 is the same as the radial thickness l of the permanent magnets (8), (10) and the radial thickness of the stator arc members (4), (6). Contains. The radial thickness 13 is the radial thickness of the permanent magnets (8), (10), the radial thickness of the stator arc members (4), (6), and the radial thickness of the stator yoke (2). It includes the The ratio of 12'/13 desired here has a value of 0.44±20% for a two-pole motor. That is, in a motor having two or more pole pieces, the following holds true. Therefore, the desired range of 12/13 is 0.35 to 0.53 for a two-pole motor. Motor 1 performance is further determined by taking the ratio of 13 to the inner diameter of the pole pieces to a value of 0.39 + 15% - 5% in the case of a 2-pole motor, i.e. This can be improved by doing this. Therefore, the bipolar mode
Taniokel 137'l, D, (inner diameter) range 0
．． 37 to 0.45. Further motor performance improvements will be made on 12/1. D, (7) can also be achieved by setting the ratio to a value of O,,17+15%, that is, by setting the range to 0.14 to 0.20. Therefore, the actual 14.12.13 and 1.1 drawn in FIG. D.

It will be understood that all of these ratios fall within the ranges mentioned above. It should be noted that the present invention can be applied to motors with two poles, four poles or more.

Referring to FIG. 2, a perspective view of the permanent magnet stator of FIG. 1 is depicted. In Figure 2', a permanent magnet (8
), the arc-shaped member located below (10) is the yoke (2)
It will be understood that it is formed integrally with the This 9th stator has two stages between the poles (11).

(12).

The high performance characteristics of the present invention will be more clearly recognized from several experimental examples described below, comparing the motor of the present invention with a conventional general servo motor.

EXPERIMENTAL EXAMPLE I Referring to FIG. 3, a current of 27.8 amperes is applied to the stator of FIGS.
3> is shown enlarged to be half of the magnetic flux distribution when it is supplied. The stator yoke (2) and the armature (13) with a plurality of winding slots (14) are partially shown schematically. The arc-shaped permanent magnet (8) is made up of a plurality of small magnets, and preferably one or two small magnets. The yoke (2) has a stepped area between poles (
11) and (12).

ing. The long, irregular lines in the figure indicate the magnetic flux generated at successive stopping points of this servo motor. In the stepped interpolar regions (11) and (12>), there is virtually no magnetic path, and the angle of the radial displacement hector formed by the magnetic path is about 8°.

The scale drawn on the bottom of FIG. 3 is used to determine the size of the magnetic path in inches as measured from the center of this servo motor.

Experimental Example ■ Fig. 4 is an enlarged diagram showing half of the magnetic flux distribution generated in a conventional servo motor. This conventional servo motor consists of a stator yoke (16), a permanent magnet (17), and an armature (18) having a plurality of slots (19). The outer diameter of the yoke (16) is equal to the outer diameter of the yoke (2) of the present invention shown in FIG. 3, and the outer diameter of the armature (1 armature) is equal to the outer diameter of the armature (13) of the present invention. When a current of 278 amperes is supplied to the windings of the armature (18), the magnetic path at the load point similar to Experimental Example I is then represented by the long and narrow irregular line in this figure. , the number of magnetic paths in the interpolar region (20), <21) increases, and the angle of the radial displacement hectare becomes approximately 11°. The magnetic flux shear in Experimental Example I is 3° less than the magnetic flux shear in Experimental Example H. This magnetic flux shear is formed by the armature reaction described above.

Experimental Example ■ Referring to Figure 5, the magnetic flux distribution generated when a current of 192 amperes is passed through the armature (13) in the device of the present invention as shown in Figures 1.2 and 3 is expanded by half. It is shown as This 192 ampere current is provided as twice the rated peak current. As is clear from this figure, the stepped interpolar regions (11), (1
Several magnetic paths are also formed in 2), and the slip angle of the polar displacement hector is about 33 degrees.

EXPERIMENTAL EXAMPLE ■ Referring to FIG. 6, half of the magnetic flux distribution when a current of 192 amperes is passed through the conventional servo motor shown in FIG. 4 is shown enlarged. That is, this servo motor includes a yoke (16), a boss magnet (17), and an armature (18).

It can be seen that the load in Experimental Example (2) is equal to the load in Experimental Example (2), and that the number of magnetic paths in the interpolar regions (19) and (20) increases extremely significantly.

This increase in the number of magnetic paths indicates armature reaction and correspondingly poor performance. The angle of the radial displacement vector in this case is approximately 50'', which represents 17° greater than the flux shear in the apparatus of the invention shown in FIG.

The reduced number of magnetic paths and short lines of magnetic flux in the device of the present invention indicate that armature reaction is weakened and performance is improved.

Referring to FIGS. 7 and 8, there are shown performance curves for the servo motor of the present invention and the conventional servo motors of FIGS. 4 and 6, respectively.

As is clear from these figures, the servo motor of the present invention can commutate a capacity of 11.78 P' during acceleration and deceleration between 5000 rpm and 3000 rpm, whereas the conventional servo motor can commutate a capacity of 8. It only gives you 7 HP. Accordingly, the servo motor of the present invention has an approximately 3.
4% larger capacity can be rectified.

Although the present invention has been described above, it will be obvious to those skilled in the art that various modifications may be made within the scope of the present invention.

[Brief explanation of the drawing]

1 is a sectional view of a permanent magnet stator drawn approximately to scale with a stepped interpole region; FIG. 2 is a perspective view of the boss magnet stator of FIG. 1; and FIG. 3 is a device according to the invention. Figure 4 is an enlarged end view showing half of the magnetic flux distribution when a current of 27.8 amperes is passed through a conventional servo motor. , FIG. 5 is an enlarged end view showing half of the magnetic flux distribution when a current of 192 amperes is passed through the device of the present invention, and FIG. 6 is an enlarged end view showing the magnetic flux distribution when a current of 192 amperes is passed through a conventional servo motor. FIG. 7 is a graph showing the performance curve of the device of the present invention, and FIG. 8 is a graph showing the performance curve of the conventional servo motor.

Claims (1)

[Claims] (1) A permanent magnet commutator type having a wire-wound core armature;
C. In a servo motor, a permanent magnet stator core including an annular yoke having a central axis opening, and arcuate permanent magnets arranged within the opening at equal intervals around the axis of the yoke, each having an arcuate permanent magnet;
The magnet includes an arc-shaped member of a magnetic body in the middle of the permanent magnet and the yoke, and adjacent edges of the arc-shaped magnet and the arc-shaped member of the magnetic body form a stepped interpolar region. C. A servo motor, including a permanent magnet type stenitor characterized by having a plurality of permanent magnet pole pieces. (2) The annular yoke and the magnetic arc-shaped member are integrally formed. ? 1. 7. A servo motor according to claim (1). , (3) Patent scope No. (3) characterized in that the annular yoke consists of a tubular body.
Servo motor described in section 1). (4) The servo motor according to claim (3), characterized in that the servo motor is formed from a plurality of disks in which the annular yoke made of the tubular body and the arc-shaped member are bundled together as a layered body. (5) Claim (3) characterized in that the magnetic arc-shaped member is fixed to the annular yoke.
Servo motor described in section. (6) The ratio of the combined radial thickness of the arc-shaped permanent magnet and the magnetic arc-shaped member to the combined radial thickness of the arc-shaped permanent magnet, the magnetic arc-shaped member, and the arc-shaped yoke is 0. 44±20% of the servo motor according to claim (1). (7) The servo motor according to claim (6), wherein the permanent magnet stator has two permanent magnet pole pieces. (8) The servo motor according to claim (6), wherein in the permanent magnet pole piece, the ratio is 2.56. (9) The ratio of the combined radial thickness of the arc-shaped permanent magnet, the magnetic arc-shaped member, and the annular yoke to the inner diameter of the arc-shaped permanent magnet within the yoke is 0.39-
The servo motor according to claim (6), characterized in that the ratio is 5%+15%. q■ Claim No. (9') R2, characterized in that the ratio is
Built-in servo motor. (11) The combined radial thickness of the arc-shaped permanent magnet and the magnetic arc-shaped member and the inside of the yoke! The servo motor according to any one of claims (6) to (G), characterized in that a ratio of J to the inner diameter of the arc-shaped permanent magnet is 0.17±15%.