JPS59226632A - Brushless motor - Google Patents

Abstract

PURPOSE:To omit a frame by uniformly forming the magnetic resistance of a yoke over the outer periphery, interposing a stator formed with an oblique slot between two side disc rings, clamping them by a bolt and mounting on a cover, and clamping via a through bolt. CONSTITUTION:A stator core 26 is formed by laminating stator electric iron plates 32 in the prescribed thickness in an oblique slot shape. A plurality of holes 35 for through bolts are formed at a yoke 34 which is formed at the outer peripheral side of the slot 23 of the plates 32. Further, a thick portion is formed on the outer periphery of the holes 35 so that the magnetic resistance Ra of a magnetic flux phi which passes the yoke 34 does not alter at the hole 35. After the plates 32 are laminated, through bolts 30, 31 are inserted into the holes 35, and clamped with side disc rings 28, 29.

Description

[Detailed description of the invention] Industrial applications The present invention is a two-vane motor used as a drive source for machine tools, robots, etc. This invention relates to a stator for a brushless motor.

Conventional structure and its problems In recent years, the automation of factories has progressed, and the machine tools used in factories,
There is a need to increase the reliability of robots, etc. Conventionally, DC servo motors with relatively simple control circuits have been used as drive sources for this type of machine tools, robots, etc., but they are unreliable due to the electrical contact points of brushes and commutators. Maintenance and inspection of the electric motor, such as replacement and cleaning of brush powder, is essential, and there is also the problem of deterioration of insulation resistance due to adhesion of brush powder. Therefore, recently, brushless motors without brushes or commutators have been attracting attention, although the control circuits have become somewhat more complex.With advances in semiconductor integrated circuit technology, complex control circuits have become cheaper, and DC servo motors have replaced brushless motors. There is a tendency to change.

In principle, a brushless electric motor has a rotor made of a permanent magnet, and a stator usually has an armature winding around a slotted core. In such a configuration, since the magnetic resistance of the air gap between the rotor and the stator changes depending on the slot, cogging torque occurs, which adversely affects the vibration of the motor and the accuracy of the stopping position. For this reason, it is possible to provide diagonal slots, but since it is difficult to form diagonal slots on the rotor side, the stator side is usually made with diagonal slots.

A conventional brushless electric motor will be explained below. 1st
The figure shows the structure of a conventional brushless electric motor.

A rotor 1 has 2P field magnets, and is fixed to a rotating shaft 2. 3 is a rotor position detector that provides a signal to drive the brushless motor; 4 and 6 are covers that rotatably support the permanent magnet rotor 1 via bearings 6 and 7; and 8 is a stator in which diagonal slots are formed. The stator consists of a core 9 and a winding 10, and 11 is a frame that holds the stator 8 and is attached to the cover 4.5.

In the above configuration, the rotor 1 has two rotors as shown in FIG.
It is composed of P field magnets 12 and salient poles 13, a non-magnetic boss 4, and non-magnetic side discs 15 and 16. The stator 9 is constructed by laminating stator electric iron plates 17 with a predetermined thickness so as to form diagonal slots, and welding them together in a recess 18 provided on the outer periphery of the stator electric iron plates 1, as shown in Fig. 3. It is formed. The outer periphery of this stator core 9 is cut, press-fitted into the frame 11 shown in FIG. was the conventional method. However, in this method, the frame 11 becomes indispensable, and the inner periphery of the frame 11 must be cut to fix the stator 8 by press-fitting. In addition, since screw holes must be provided at the ends of the frame 11, the frame 11 becomes expensive, and the number of man-hours required to cut the outer periphery of the stator 8 increases, resulting in an increase in manufacturing costs. Furthermore, since the frame 11 needs to have a certain degree of thickness, there is a drawback that the outer periphery of the electric motor becomes thick. Further, the recessed portion 18 which becomes the welded portion shown in FIG. 2 is a slot.

Since the yoke part 20 is formed on the outer circumference of the yoke part 19, the width of the yoke part 20 becomes narrow at the concave part 18, and the magnetic resistance of the magnetic flux across the yoke part 5 page 20 becomes uneven, which causes cogging torque. OBJECT OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and aims to simplify the structure, facilitate assembly of the product, and suppress the generation of cogging torque. It is.

Structure of the Invention The brushless electric motor of the present invention has a stator whose yoke portion has a uniform magnetic resistance over its outer circumference, which is sandwiched between two side disk rings, which are tightened with bolts. Cut the end face.

It is fixed to the cover with through bolts, and since a frame is not required, it is inexpensive, requires less cutting, and manufacturing costs are also reduced. The outer circumference of the electric motor can also be made smaller. Furthermore, since the magnetic resistance of the yoke is uniform, the generation of cogging torque is reduced, and the cogging torque generated at the through-bolt section of the yoke is dispersed and reduced, making it possible to provide a high-performance brushless motor at an inexpensive price. It is.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure shows the structure of the brushless electric motor of the present invention. 21 is a rotor having 2P field magnets; 22 is a rotor position detector that provides a signal to drive the brushless motor; 23924 is a cover that rotatably supports the permanent magnet rotor 21; A long hole is provided. Reference numeral 25 designates a stator core 26 in which diagonal slots are formed and a stator which is twisted with a winding 27. Reference numerals 28 and 29 designate side disc rings that sandwich the stator 25 from both sides, which are tightened with bolts 3o, and the stator 25 is tightened with bolts 3o. It is integrated with.

The stator 25 is attached to the cover 23.24 by a part of the spigot provided on the outer diameter side of the side disc ring 28.29.
Tightening is fixed with a through bolt 31.

In the above structure, the stator core 26 is constructed by laminating the stator electric iron plates 32 shown in FIG. 5 so as to form a diagonal knee slot with a predetermined thickness. As shown in FIG. 5, a yoke portion 34 formed on the outer diameter side of the slot 23 of the stator electric iron plate 32 is provided with a plurality of holes 35 for through bolts. The number of slots in the electric iron plate 32 is n.

When the diameter of the through bolt is 1, the hole is a long hole with a width of 1 and a length of an opening angle of 2π/n from the center axis of the costotrochanter.

Furthermore, the magnetic resistance Ra of the magnetic flux φ passing through the yoke part 34 is
It does not change at the hole 35 for the through bolt.
The outer periphery of the through bolt hole 35 is thickened so that e = Ra.

According to this embodiment configured as described above, even if the stator electric iron plates 32 are stacked and formed into diagonal slots, the through bolts 30° and 31 can be inserted into the through bolts X35, and the side circular The stator electric steel plate 32 can be fixed with plate rings 28°29. In addition, by performing spigot cutting on the side surfaces of the side disc rings 28 and 29 with reference to the inner diameter of the stator, the parallelism of the end surfaces and concentricity with respect to the inner diameter due to the lamination of electric iron plates can be precisely suppressed. be able to.

Furthermore, when the number of pole pairs P of the field magnet is 2 and the stator core 9 shown in FIG. 3 is used, slot cogging cannot be completely eliminated even if the stator core 9 is formed into diagonal slots. As shown in FIG. 6, slot cogging of ΔTs remains. At the same time, cogging ΔTB due to the JB recess 18 shown in FIG. 6 occurs due to the four portions 18 that become the welded portions shown in FIG.

This is because the number of four portions 18 in FIG. 3 is equal to 2P, so the cogging ΔTa+ caused by one recess is amplified four times as shown in FIG. 7, resulting in a cogging torque ΔTa of 4ΔTB1.

When the stator core 26 according to this embodiment is used, the magnetic resistance near the through bolt holes in the outer yoke portion 34 is represented by Rb and Re as shown in FIG. Since the resistors R and Rb+R0 are formed to have the same value, it is possible to reduce the cogging torque T a '1ij applied to one through bolt hole. Furthermore, when the number of pole pairs P of the field magnet is 2, the number of through bolt holes is 722 or more prime number 9'=', that is, 3. 5. 7..., so as shown in Figure 8, the phase of the cogging torque due to the through bolt holes is shifted by 1200, so the effect is that the combined cogging torque becomes almost zero0. Since the frame is small, the outer diameter of the motor can be reduced, and component costs can also be reduced.

Since only the processing of the side disc ring is required, an inexpensive brushless electric motor can be obtained. Furthermore, the stator core protrudes into the outside air, and the cooling area increases due to the unevenness formed on the outer diameter side of the stator core, which also has the effect of improving heat dissipation. The magnetic resistance of the stator is made uniform over the outer circumference, and the stator formed in diagonal slots is held between two side disk rings and fixed with bolts, and the cover is fixed with through bolts, so the frame is omitted. This makes it possible to realize an excellent, inexpensive brushless electric motor that does not generate cogging torque.

[Brief explanation of the drawing]

Fig. 1 is a half-cut sectional view of a conventional brushless electric motor, Fig. 2 is a half-cut sectional view of the rotor, Fig. 3 is a front view of the stator electric iron plate, and Fig. 4 is a sectional view of the brushless electric motor according to the present invention. , Figure 6 is a front view of the same stator electric iron plate, Figures 6 and 7.
The figure is a waveform diagram showing the cogging torque of a conventional example, and FIG. 8 is a waveform diagram showing the cogging torque of the present invention. 21...Permanent magnet rotor, 23.24...
... Cover, 25 ... Stator, 26 ... River stator core, 28° 29 ... Side disc ring, 30
．． 31... Bolt, 32... Stator electric iron plate, 33... Slot, 34...
Yoke part, 36... hole. Name of agent: Patent attorney Toshio Nakao and 1 other person
- ~ Transfer Fig. 5 JP-A-5!1l-226632 (5) Fig. 6 Rotation angle O Fig. 7 Rotation Hei No. 8 Ri 1 1 1

Claims (1)

[Claims] A rotor having 2P field magnets, two covers that rotatably support the U01 trochanter, two side disc rings with a plurality of elongated holes, and a yoke part on the outer periphery of the slot. A stator electric iron plate with uniform magnetic resistance over the outer circumference and provided with a cumulative number of elongated through holes of 3/2P or more and a cumulative number of elongated holes for attaching the side disk ring of 3/2P or more. The stator electrical iron plates are stacked to a predetermined thickness so as to be immersed in the diagonal slots, and are clamped in the axial direction by the side disc rings,
A brushless electric motor in which the tightening is fixed with bolts, the cover is fitted into a part of the spigot formed on the side disc ring, and the tightening is fixed with a through bolt.