JPS62203543A - Brushless motor - Google Patents

Abstract

PURPOSE:To improve the efficiency of a magnetic flux which flows to a stator core by providing a groove for forming a magnetic reluctance obliquely on the end face of each pole of a stator core. CONSTITUTION:A magnetic flux from one pole 4a of a magnet unit 4 flows through the end of a pole 5 to the pole 5 of a stator core 7. At this time, part of the magnetic flux tends to flow to adjacent reverse polarity pole 4b side, but the flow is interrupted by a grove 11, and the magnetic flux resultantly efficiently flows from the unit 4 to the core 7. Since the groove 11 is obliquely formed between opposite sides 5a1 and 5a2, the magnetic flux interrupting effect of the grove 11 affects the entire end face 5a to continuously occur against the rotation of the unit 4, thereby sufficiently enhancing the efficiency of the magnetic flux flow to the core 7.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to improvements in brushless motors.

[Prior Art] For example, in floppy disk devices, etc., there is a demand for miniaturization of the device, so flat brushless motors are used for disk drives. Such flat brushless motors are shown in FIGS. 10 and 11, for example.
As shown in the figure, a disk-shaped rotor yoke 2 whose edge is bent into an L-shape is connected to a rotating shaft 1 by screws 3.

A ring-shaped magnet body 4 is fixed to the inner side of the edge of the rotor yoke 2. The ring-shaped magnet body 4 is made up of a plurality of magnetic poles made of fixedly magnetized magnets. On the other hand, a plurality of poles 5, 5 . ...and each pole 5.5
．． A flat status core 7 formed by winding wires 6, 6 degrees, . This status core 7 is constructed by laminating, for example, a plurality of silicon steel plates. The rotating shaft 1 is rotatably provided with respect to the stator core 7 and the housing 8.

Conventionally, in such a brushless motor, the tip of the pole 5 has a T-shaped opening in the circumferential direction of the stator core 7, as shown in FIG. 5 at a substantially right angle upward along the axial direction of the rotating shaft 1, and the bottom piece of the steel plate is bent substantially at a right angle downward along the axial direction of the rotating shaft 1 to make it wider. The end face 5a of the magnet body 4 was provided with a predetermined gap on the inner surface of the magnet body 4.

With this configuration, even if the motor is made thin, each pole can have a large area facing the magnet 4.
As a result, the magnetic flux from the magnet poles flows relatively efficiently to the stator core 7, and the output of the motor does not decrease significantly.

[Problems to be Solved by the Invention] However, in this conventional device, since the tip end surface 5a of the pole 5 in the stator core 7 is flush with the other end, as shown in FIG. A part of the magnetic flux f flows through the tip of the pole 5 again to the adjacent magnet tffi 4b of opposite polarity in the magnet body 4, reducing the efficiency of the magnetic flux flowing to the stator core 7, and as a result, sufficient motor output cannot be obtained. The problem was that there was no.

This invention was made to solve such problems, and an object thereof is to provide a brushless motor that can improve the efficiency of magnetic flux flowing from the magnet body to the stator core and improve the motor output. .

[Means for Solving the Problems] The present invention has a structure in which the tip of each pole of a flat stator core has a wide surface in the direction of the rotation axis, and the tip surface is attached to the magnetic pole surface of the magnet body of the rotor yoke. In the brushless motors, which are opposed to each other with a predetermined gap between the two poles, grooves for forming magnetic resistance are provided diagonally on the tip surface of each pole.

[Operation] In the present invention having such a configuration, the magnetic flux flowing from the magnetic pole surface of the magnet body to the stator core does not flow to the adjacent magnetic pole side due to the magnetic resistance caused by the grooves, and therefore flows efficiently to the stator core. Further, since the grooves are provided diagonally, the magnetic resistance due to the grooves can be applied continuously to the rotation of the magnet body.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

Note that the basic configuration is the same as the conventional one as shown in FIGS. 10 and 11, so it will be omitted and only the main parts will be described.

As shown in FIGS. 1 and 2, the opposite side 5 a 1 in the axial direction of the rotating shaft 1 is attached to the tip end surface 5 a of the pole 5 of the stator core 7.
A groove 11 having a U-shaped cross section for forming magnetic resistance is diagonally cut between +5 and a2.

With such a configuration, the magnetic flux from one magnetic pole 4a of the magnet body 4 flows to the pole 5 of the stator core 7 via the tip of the pole 5, as shown in FIG. At this time, a part of the magnetic flux tries to flow toward the adjacent magnetic pole 4b of opposite polarity, but the groove 11 blocks this flow, and as a result, the magnetic flux efficiently flows through the magnet body 4 to the stator core 7.

Moreover, since the groove 11 is diagonally carved between the opposing sides 5a1 and 5a2, the magnetic flux blocking effect by the groove 11 extends over the entire tip surface 5a and occurs continuously as the magnet body 4 rotates. The efficiency of the flow of magnetic flux to the stator core 7 can be sufficiently increased.

As a result, sufficient motor output can be obtained even if the motor is configured to be thin. In other words, the same motor output as the conventional motor can be obtained with a thinner structure than the conventional motor.

Next, another embodiment of the invention will be described with reference to the drawings.

In the case shown in FIG. 4, a groove 12 for forming magnetic resistance is carved so that the left and right areas divided by the groove are equal to the tip surface 5a of the pole 5, that is, it passes through the center of the tip surface 5a. With this configuration, in addition to the effects of the embodiments described above, the magnetic balance of each pole is improved, and the occurrence of cocking can be reduced.

Furthermore, in the one shown in FIG. 5, a groove 13 for forming magnetic resistance is carved between opposite sides 5a1 and 5a2 which are in contact with the diagonal portion of the tip surface 5a of the pole 5.
3 passes through the center, the left and right areas divided by the groove 13 are equal, and therefore the same effect as in FIG. 4 can be obtained. Furthermore, in this embodiment, the grooves 13 extend as far as possible in the rotational direction of the magnet body 4, so that the continuity of the magnetic flux blocking effect can be further enhanced.

In addition, the one shown in FIG. 6 has a curved groove 14 for forming magnetic resistance passing through the center between opposite sides 5a1 and 5a2 that contact diagonally opposite corners of the tip surface 5a of the pole 5. Even with this configuration, the same effects as in FIG. 5 can be obtained.

In this case, the groove 14 may be carved between the opposite sides 5a1 and 5a2 without contacting the diagonal portions or passing through the center.

7 shows a groove 15 for forming magnetic resistance, which includes a straight portion partially passing through the center coincident with the axial direction of the rotating shaft 1 between the opposite sides 5al and 5a2 with respect to the tip end surface 5a of the pole 5.
The same effect as that shown in FIG. 4 can be obtained even in this manner.

Furthermore, the one shown in FIG. 8 has a groove 16 for forming magnetic resistance, which is V-shaped in cross section and whose side opposite to the rotational direction of the magnet body 4 is substantially perpendicular, formed on the tip surface 5a of the pole 5. Even with such a configuration, the same effects as those of the embodiment described above can be obtained. Further, in this embodiment, since the side of the V-groove 16 on the opposite side to the rotation direction of the magnet body 4 is made substantially perpendicular, the wind pressure in the groove portion due to the rotation of the magnet body 4 can be minimized.

Furthermore, the groove shown in FIG. 9 has a U-shaped cross section, and even with this configuration, the same effects as in the previous embodiment can be obtained.

In addition, in the above embodiment, the groove is formed on the opposite side 5a1 of the pole tip surface.
Although we have described grooves carved between 5a and 2, the invention is not necessarily limited to this, and even if grooves are carved diagonally between the other opposing sides perpendicular to the direction of the rotation axis, the effect of blocking the magnetic flux will be partially reduced. This makes it possible to improve the efficiency of magnetic flux flowing to the stator core.

[Effects of the Invention] As detailed above, according to the present invention, grooves for forming magnetic resistance are provided diagonally on the tip end surface of each pole of the stator core, so that part of the magnetic flux flowing from the magnet body to the stator core is transferred to the magnet body. Since the magnetic flux is prevented from returning to the stator core, the efficiency of the magnetic flux flowing to the stator core can be improved, and the motor output can be improved.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention. Figure 1 is a perspective view of the main part, Figure 2 is a plan view of the tip of the pole, and Figure 3 is the effect of the groove for forming magnetic resistance. FIGS. 4 to 7 are plan views of the pole end surface showing other embodiments of the invention, and FIGS. 8 and 9 show still other embodiments of the invention. Partially enlarged views shown in Figures 10 and 11
The figure shows the basic configuration of a brushless motor.
The figure is a partial sectional view, FIG. 11 is a plan view with the housing removed, and FIGS. 12 and 13 are conventional examples.
FIG. 2 is a partial perspective view, and FIG. 13 is a partial enlarged view for explaining the operation. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Rotor yoke, 4... Magnet body, 5... Pole, 5a... Tip surface, 6...
・Winding wire, 7... Stator core, 11, 12, 13.1
4,15°16.17... Groove for forming magnetic resistance. Applicant's Representative Patent Attorney Takehiko Suzue Figure 3 Figure 4 Figure 5 Figure 8 Figure 9 Figure 10 Figure 11

Claims (7)

[Claims] (1) A rotor yoke that is connected to a rotating shaft and configured in a ring shape with a plurality of magnetic poles made of fixedly magnetized magnets with their magnetic pole faces facing inward, and a rotor yoke that has a plurality of poles protruding in the circumferential direction and each of the poles. Wrap a winding around each pole,
In the brushless motor, each of the above-mentioned brushless motors comprises a flat stator core, in which the tip of each pole has a wide surface in the direction of the rotation axis, and the tip surface faces the magnetic pole surface of the rotor yoke with a predetermined gap therebetween. A brushless motor characterized by having a diagonal groove for forming magnetic resistance on the tip surface of the pole. (2) A brushless motor according to claim (1), characterized in that a groove for forming magnetic resistance is provided diagonally on the tip end surface of the pole between opposite sides of the surface in the direction of the rotation axis. (3) A brushless motor according to claim (1), characterized in that a groove for forming magnetic resistance is provided on the tip end surface of the pole so that the area of each surface divided by the groove is equal. (4) The brushless motor according to claim (2), characterized in that a groove for forming magnetic resistance is provided between opposite sides that are in contact with diagonals. (5) Claim (1) characterized in that the groove for forming magnetic resistance is formed including a part of the straight straight part.
Brushless motor as described in section. (6) The brushless motor according to claim (1), wherein the groove for forming magnetic resistance is formed in a curved line. (7) The brushless motor according to claim (1), wherein the groove for forming magnetic resistance is formed to have a V-shaped cross section.