JPH0378458A - Motor - Google Patents

Abstract

PURPOSE:To improve the magnetic uniformity of a stator core and to reduce cogging torque by fixing the end section of an auxiliary magnetic pole to the end section of the main magnetic pole of a stator core while overlapping. CONSTITUTION:A stator core 1 is positioned on a housing 3 and laminated thereon, a coil 2 is wound around a main magnetic pole 1a, an auxiliary magnetic pole 1b is assembled into a stator core 1, and then they are contained in the housing 3. At this time, an overlapped section 11 is formed at the facing end section of the auxiliary magnetic pole 1b and the main magnetic pole 1a of the stator core 1. Since the overlapped section 11 is formed at the facing section of the main magnetic pole 1a and the auxiliary magnetic pole 1b, magnetic resistance in a space between the main and auxiliary magnetic poles can be suppressed and leakage flux can be reduced. Consequently, magnetic uniformity of the stator core 1 is improved and variation of magnetic energy to be stored in a field, produced through relative rotation of a rotor yoke 4 and the stator core, can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric motor, and more particularly to an electric motor such as a brushless motor with several cores facing each other.

[Prior Art] FIG. 5 is a vertical cross-sectional view of a conventional three-phase bipolar drive type brushless motor with several cores opposed to each other, and FIG.
It is a sectional view along the A line. A stator core 1 made of 5 silicon steel plate and having main magnetic poles 1a radially formed thereon is positioned and laminated to a housing 3 which is disc-shaped and has a bearing cylinder formed in the center. magnetic pole 1a
A coil 2 is wound around each.

The shaft 7 is connected to the bearing cylinder of the housing 3 via the bearing 8.
is rotatably attached, a flange 6 is press-fitted into the end of this shaft 7, and a rotor yoke 4 is attached to this flange 6.
is fixed, and a multi-pole magnetized rotor magnet 5 is fixed on the inner circumferential surface of the rotor yoke 4 in close opposition to the circumferential surface of the stacked stator cores 1.

A driving circuit board 9 on which a Hall element is attached at a predetermined position is fixed on the bottom of the housing 3.

In this conventional multi-core facing brushless motor, the current flowing through the coil 2 is sequentially switched by the circuit board 9 according to the motor rotation angle, so that the rotor magnet 5 fixed to the rotor yoke 4 is connected to the stator core 1. This movement causes the rotor yoke 4 to rotate around the shaft 7.

[Problems to be Solved by the Invention] In the conventional brushless motor with several cores facing each other, as shown in FIG.
A groove portion 10 is formed in between.

When this groove 10 exists, magnetic non-uniformity occurs in the stator core 1 because the magnetic resistance of the groove 10 is larger than that of the stator core 1. When magnetic non-uniformity occurs in the stator core 1 in this way, the magnetic energy stored in the magnetic field between the rotor yoke 4 to which the rotor magnet 5 is fixed and the stator core 1 changes depending on the relative rotation of the two. When the magnetic energy stored in the magnetic field between the rotor yoke 4 and the stator core 1 changes in accordance with the relative rotation thereof, cogging torque is generated between the two.

FIG. 7 is a characteristic diagram of the cogging torque between the rotor yoke and the stator core. When such cogging torque occurs, the rotor yoke must have a large inertia in order to reduce speed fluctuations due to the cogging torque during normal rotation.

In order to reduce this cogging torque, an electric motor having a structure in which an auxiliary salient pole part is extended from the stator core 1 in the groove part 10 shown in FIG. There is.

However, even in the electric motor according to this proposal, since there is a gap between the newly formed auxiliary salient pole part and the opposing main pole, the cogging torque is affected, and it is not sufficient.

An object of the present invention is to provide an electric motor that can significantly reduce cogging torque with a simple structure.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a magnetic flux generating means having a multi-pole magnetized magnet, and a magnetic flux generating means arranged opposite to the magnetic flux generating means to create a closed magnetic path of the magnetic flux. a stator core having a main magnetic pole, and a plurality of coils wound around the main magnetic pole of the stator core within a magnetic field formed by the magnetic flux generating means and the stator core, and a plurality of coils wound around the main magnetic pole of the stator core, the current flowing through the coil is , in an electric motor in which the magnetic flux generating means is rotationally driven relative to the stator core by sequentially switching according to the motor rotation angle, an end of the auxiliary magnetic pole is opaque to an end of the main magnetic pole. It becomes.

[Function] In the present invention, since the auxiliary magnetic pole is attached to the stator core in which a coil is wound around the main magnetic pole so as to overlap the main magnetic pole and the end thereof, the magnetic non-uniformity of the stator core is improved. leakage magnetic flux is reduced.

This results in a significant reduction in cogging torque.

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

FIG. 1 is a sectional view corresponding to FIG. 6, in which the same parts are given the same reference numerals.
is installed.

FIG. 2 is an enlarged view of the stator core of the embodiment. As shown in the figure, the auxiliary magnetic pole 1b is formed separately and has a structure that can be fixedly assembled to the stator core 1. Auxiliary magnetic pole 1b
An overlap portion 11 is formed at opposite ends of the main magnetic poles 1a of the stator core 1.

FIG. 3 is an explanatory diagram of the magnetization of the rotor magnet of the embodiment. As shown in the figure, in the embodiment, the rotor magnet 5 is magnetized in a flower pattern shape with each magnetic pole as the center. ing.

In the embodiment, after the stator core 1 is positioned and stacked in the housing 3 and the coil 2 is wound around the main magnetic pole 1a, the auxiliary magnetic pole 1b is assembled and fixed to the stator core 1, and then the auxiliary magnetic pole 1b is assembled and fixed to the housing 3. A stator core 1 and an auxiliary magnetic pole 1b are housed and arranged.

Note that the other configuration is similar to the conventional case already explained using FIG. The rotor yoke 4 is attached to the flange 6 press-fitted into the
is fixed, and on the inner peripheral surface of the rotor yoke 4, a multi-pole magnetized rotor magnet 5 is fixed as shown in FIG. 3 in close opposition to the peripheral surface of the stacked stator core 1. Furthermore, a circuit board 9 on which a Hall element is attached at a predetermined position is fixed to the bottom plate of the housing 3.

As shown in FIG. 2, an overlap portion 11 is formed in the opposing portion of the main magnetic pole 1a and the auxiliary magnetic pole 1b.
Compared to the electric motor proposed in Japanese Patent No. 754, an increase in magnetic resistance in the space between the main magnetic pole 1a and the auxiliary magnetic pole 1b can be suppressed, and leakage magnetic flux can be reduced.

In this way, when the leakage magnetic flux is reduced in the space between the main magnetic pole 1a and the auxiliary magnetic pole lb and the magnetic non-uniformity of the stator core 1 is improved, the The change in magnetic energy stored in the magnetic field between the two ends is reduced, and the cogging torque is reduced.

FIG. 4 is a characteristic diagram of the cogging torque between the rotor yoke and the stator core in the embodiment, which is significantly reduced compared to the conventional one already explained using FIG. 7.

In this manner, in the embodiment described above, cogging torque can be reduced, so high rotation accuracy with little torque fluctuation can be obtained. Also, during the assembly process, the main magnetic pole 1
After winding the coil 2 around the stator core 1, the auxiliary magnetic pole 1b is assembled and fixed to the stator core 1. Therefore, the winding of the coil 2 is easy and the manufacturing process proceeds smoothly.

Furthermore, since the cogging torque is reduced, there is no need to provide the rotor yoke with large inertia for the purpose of suppressing speed fluctuations due to the cogging torque, and the rotor yoke can be made smaller and lighter.

In the above embodiment, a rotor magnet is magnetized in a flower pattern to create a multi-pole magnet, but the present invention is not limited to the embodiment. It is also possible to arrange magnets formed into a shape to form a multi-pole magnetized magnet. Further, in the above embodiment, a three-phase bipolar driving type electric motor has been described, but the present invention can also be applied to other driving type 1, for example, a unipolar driving type electric motor.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a compact and lightweight electric motor that can be easily assembled, reduces cogging torque, and has high rotational accuracy.

[Brief explanation of drawings]

1 to 4 are diagrams explaining the present invention in detail, with FIG. 1 being a sectional view, FIG. 2 being a partially enlarged view of the stator core, and FIG. Figure 4 is a characteristic diagram of cogging torque between the rotor yoke and stator core.
Figures 5 to 7 are diagrams explaining conventional electric motors.
The figure is a longitudinal sectional view, FIG. 6 is a sectional view taken along the line A-A in FIG. 5, and FIG. 7 is a characteristic diagram of cogging torque between the rotor yoke and the stator core. 1... Stator core, 1a... Main magnetic pole, 1b... Auxiliary magnetic pole, 2... Coil,
3...Housing, 4...Rotor yoke, 5...Rotor magnet, 6...
Flange, 7...Shaft, 8...Bearing, 9...Circuit board. Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] a magnetic flux generating means having a multipolar magnetized magnet;
A stator core having a main magnetic pole, which is arranged opposite to the magnetic flux generating means and forms a closed magnetic path for magnetic flux, and is wound around the main magnetic pole of the stator core within a magnetic field formed by the magnetic flux generating means and the stator core. a plurality of coils, the electric motor driving the magnetic flux generating means to rotate relative to the stator core by sequentially switching the current flowing through the coils according to the motor rotation angle; An electric motor characterized in that an end of an auxiliary magnetic pole is provided to overlap an end of the auxiliary magnetic pole.