JPH02123956A - Dc brushless motor - Google Patents

Abstract

PURPOSE:To prevent the generation of torque ripple by forming a motor rotor into a cup-shaped body from magnetic material and by coaxially fitting a ring- shaped magnet inside the rotor. CONSTITUTION:When DC current is applied to a coil 18, an electric current I flows in the direction of the arrow. On the other hand, the line of magnetic force M from the N pole of a magnet 14 intersects perpendicularly to a facing coil 18, is absorbed to a toroidal core 16 and induced from a yoke 17 to the edge of a rotor 13, and returns to the S pole so that the current I intersects perpendicularly to the line of magnetic force M, a force acting in the direction of anticlockwise rotation as viewed from the top surface of a stator 15 is generated in the whole top surface and the rotor 13 rotates clockwise by reaction. Whichever angle of rotation the rotor 13 may have, a torque generated between the rotor and stator 15 is uniform over the whole periphery so that an angle of rotation-detecting element such as Hall element is made unnecessary and a driving current need not be switched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC brushless motor, and particularly to a DC brushless motor that eliminates torque ripple.

BACKGROUND ART Conventionally, DC motors used in audiovisual equipment and the like are required to have high rotational accuracy, and therefore have generally had a configuration as shown in FIG. 7 of the attached drawings.

In the same figure, the board (
2) is fixed, and the substrate (
A plurality of coils (4) (/I) are attached to the surface 2), and magnetoelectric transducers (5×5) such as Hall elements and magnetoresistive elements are arranged. On the other hand, a magnet (7) is provided on the lower surface of the rotor (6), and the lower surface of the magnet (7) is radially magnetized alternately with north and south poles. Then, the lower part of the spindle (8) fitted in the center of the rotor (6) passes through the hole (3) of the substrate (2), and the case (9) and rear cover are inserted from above and below the spindle (8). One piece of (10) is inserted and joined. A drive circuit (not shown) is connected to the substrate (2), and each coil (4X/
l)... by switching the current applied to the rotor (6
) is rotating. Also known is a DC motor in which a magnet is provided on the stator side and a coil is provided on the rotor.

[Problems to be Solved by the Invention] The conventional DC motor described above rotates the rotor by switching the current applied to multiple coils depending on the position of the magnetic poles of the magnets, which causes torque ripple and impairs rotation accuracy. This is an impediment to improvement. Furthermore, switching noise generated by the drive circuit may become a problem. Therefore, a technical problem arises that must be solved in order to eliminate the torque ripple and suppress the generation of switching noise, and the present invention aims to solve this problem.

[Means for Solving the Problem] The present invention has been proposed to achieve the above object, and includes a spindle provided at the center of a cup-shaped rotor made of magnetic material, and a spindle provided at the center of the rotor. A ring-shaped magnet is coaxially attached to the magnet, an S pole is magnetized on one side of the magnet, and an N pole is magnetized on the other side, and a conductive wire is wound radially around the core of the annular coil. It is an object of the present invention to provide a DC brushless motor, characterized in that a yoke is provided on the rotor, and the coil is fixed so as to face the magnet of the rotor.

1 Effect] According to the present invention, a rotor of a motor is formed into a cup shape using a magnetic material, and a ring-shaped magnet is coaxially attached to the inside of the rotor. Then, one side of the magnet is magnetized with an S pole, and the other side is magnetized with an N pole. On the other hand, an annular coil is provided by winding an insulated conductive wire radially around the core, and a yoke is provided at the edge to form a stator. The stator is placed close to and facing the magnet of the rotor so that lines of magnetic force of the magnet flow through the coil and core of the stator and return to the other pole of the magnet to form a magnetic circuit.

When a direct current is applied to the annular coil, the lines of magnetic force are perpendicular to the coil on the side facing the magnet, so
A force is generated according to Fleming's left-hand rule in a direction perpendicular to the current flowing through the coil and the lines of magnetic force. and,
Since the coils are arranged radially, a reaction force acts on the rotor in the direction of rotation, causing it to rotate. Since the rotational force generated in the rotor is uniform over the entire circumference, no torque ripple occurs.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6 of the attached drawings. Note that the same reference numerals are used for parts having the same configuration as those used in the conventional example. 1st
The figure is a sectional view of a DC brushless motor (11). In the same figure, the thrust bearing (rotor θ, etc., which is rotatably mounted on the shaft) is formed into a cup shape using a magnetic material, and a ring-shaped magnet (1/l) is glued to the inner surface. .The magnet H has S on the surface to be joined to the rotor (1).
The pole is magnetized, and the other surface is entirely N-pole. A spindle (8) is press-fitted into the center of the rotor (1), and although not shown, the upper part of the spindle (8) protrudes from the bearing of the case.
Below (2) are stators (one closely facing each other and fixed to the rear cover (10). The stator θ is attached to the outer periphery of the toroidal core (10) as shown in Fig. 2 (^). Yokes (ri'l (r7)...) are provided at intervals.

In this embodiment, six pole yokes are provided, but the number should not be particularly limited.

Then, as shown in FIG. 2(B), the yoke (r7) (
r7) A conductive wire such as an enameled wire is wound around the entire circumference of the core part other than... to form an annular coil (IEc), and lead wires (19a) (19b) are placed at the beginning and end of the winding.
There is a drawer. These 0 stators are mounted on a pedestal (21 [phase]...
After fixing the rotor (first class spindle (8)
The stator (one child L (zQl) is loosely inserted, the case (not shown) is attached to the rear cover Qo by making it contact with the thrust bearing (121), and the rotor (1st etc.) is made freely rotatable.

Therefore, the DCC brushless morph 11) with the above configuration
When a direct current is applied to the stator (coil) installed in one of the stators, a current (1) flows, for example, in the direction shown by the arrow.On the other hand, the lines of magnetic force radiated from the four N poles
The current (M) is perpendicular to the opposing coil (1) and is absorbed by the toroidal core (1G) and is induced from the yoke (r7) to the edge of the rotor (1) and returns to the S pole.
) is perpendicular to the line of magnetic force (M), so a force in the dihedral counterclockwise rotation direction is generated on the entire top surface of the stator (+5), and the rotor (1st class) rotates clockwise as a reaction. Although the direction of the current (1) on the back side of the coil is opposite to that on the top side, the magnetic lines of force (M) are absorbed by the toroidal core (10), so they do not cross the back side of the coil. Therefore, no force is generated in the opposite direction to the upper surface side, and the rotation of the rotor (1) is not hindered.Also, no matter what rotation angle the rotor θ■ is, there is no force between the stator (1) and the Since the generated rotational force is uniform over the entire circumference, there is no need for a rotation angle detection element such as a Hall element, and there is no need to switch the drive current.

Therefore, the present invention should not be limited to the above-mentioned embodiment, but can also be constructed as shown in FIGS. 3 and 4. In FIG. 3, the outer edge of the stator (A) is made of a magnetic material such as a plastic magnet and integrally forms a yoke (C) with the base. As shown in FIG. 4, the stator (A) is constructed by winding coils radially around a toroidal core and then providing the yoke around the entire circumference by outsert molding.

Further, as another embodiment, there is a structure shown in FIGS. 5 and 6. In FIG. 5, rotors (C) and (C) are arranged facing each other on both sides of the stator (2).

In this case, rotational force is generated in the lower coil of the stator (a) and the lower rotor (a) in the same direction as the upper surface, and both sides of the coil are used, resulting in torque. The magnets (→) of both rotors (C) and (C) do not repel and attract the stator (To), so the load applied to the thrust bearing (Ll) is reduced. As shown in Fig. 6, the spindle fitting holes (4) and (1) of the rotors (C) and (C) are extended to the stator G!η side, and the rotation performance is improved. It is also possible to further improve the efficiency of the magnetic circuit by providing a center yoke (g) at the center of the magnetic field (a) to provide a feedback circuit for the lines of magnetic force (M).

Therefore, this invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that this invention extends to such modifications.

[Effects of the Invention] As detailed in the above embodiments, the present invention is such that a ring-shaped magnet is attached to a cup-shaped rotor made of a magnetic material. The magnet has an electromagnetic S pole on one side and a celadon N pole on the other side, and a coil with a Q=1 shape wound around the core is arranged as a stator facing the magnet. A yoke is provided at the edge of the stator and placed close to the rotor to form a magnetic circuit in which lines of magnetic force from the north pole pass through the fill and core and return to the south pole. Since the coil is wound radially, when a current flows, a force in the direction of rotation is generated over the entire surface of the coil due to electromagnetic induction, and the reaction causes the rotor to rotate. Since the rotational force generated by the coil is the same no matter what rotational position the rotor is in, torque ripple does not occur and extremely high rotational accuracy and stability can be obtained. Since there is no need to switch the drive current, the cause of switching noise can be eliminated, and a magnetoelectric conversion element for detecting the rotation angle is no longer required, simplifying the drive circuit, improving rotation performance and reducing costs. It can contribute to the reduction.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, in which FIG. 1 is a partially cutaway vertical sectional view, FIG. 2(A) is a plan view of the core, and FIG.
Figure (B) is a plan view of the core with a coil wound around it, Figures 3 and 4 show other embodiments, Figure 3 is a partially cutaway vertical cross-sectional view, and Figure 4 is a core with a coil wound around it. A plan view of the core, and FIGS. 5 and 6 are partially cutaway vertical cross-sectional views showing still other embodiments, respectively.
FIG. 7 is an exploded perspective view showing a conventional example. (8) --- Spindle (11) --- DCC brushless morph 1 ■ (c) --- Rotor (14) --- Magnet (1 @Qb) ... Stator (to IF9) ... Toroidal core (It) @.
...Yoke (Japanese) ...Coil (G) ...Center yoke (8) ...Spindle

Claims (1)

[Claims] A spindle is provided at the center of a cup-shaped rotor made of magnetic material, and a ring-shaped magnet is attached coaxially to the inside of the rotor.One side of the magnet is magnetized with an S pole, and the other side is magnetized with an S pole. The present invention is characterized in that a yoke is provided at the edge of an annular coil in which the N pole is magnetized and a conductive wire is wound radially around the core, and the coil is fixed facing the magnet of the rotor. DC brushless motor.