JPS642537Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a DC brushless motor.

In recent years, with the development of electronic devices, DC brushless motors have been widely used. However, a problem with DC brushless motors is that it is necessary to avoid stopping the rotor when the starting torque is zero.
It is necessary to eliminate the so-called dead center. Therefore, in the past, cylindrical field magnets were attached to the rotor with S and N poles.
They were formed by stacking the poles on each stage with appropriate shifts, or by skewing the joints of the S and N poles and combining them. However, these structures are complicated and manufacturing costs are high, and cost reduction has been a serious problem, especially for small motors.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a DC brushless motor that can be easily manufactured without complicating the rotor structure and that can reduce the manufacturing cost of the motor.

The present invention will be explained below based on examples.

FIGS. 1 and 2 show an embodiment of the present invention, which is applied to a brushless motor for a small fan with an outer rotor. The brushless motor 1 has a first
As shown in the figure, a four-pole electric field stator 3 with an auxiliary pole 2 protruding from the center is provided, and a field magnet 4 alternately magnetized to S and N poles is rotated around it as specified. A rotor 6 installed inside the child hub 5 is rotatably arranged and formed. At the end of the joint between one of the opposing S and N poles of the rotor hub 5, preferably at the end far from the Hall element 7 such as a Hall IC, as shown in FIGS. The magnetic field distribution is changed by cutting out the magnetic field line detouring portions 8, which are openings with predetermined dimensions for detouring the magnetic field lines, and the magnetic field distribution is slightly deflected to prevent the rotor 6 from stopping at the dead center. The side edge of the cutout opening is bent inward so that the bent piece 9 comes into contact with the lower end surface of the field magnet 4, as shown in FIG. 3, to facilitate attachment to the rotor hub 5. Based on this magnetic field distribution, a predetermined DC voltage is switched and controlled via the Hall element 7 to field the stator 2, thereby rotating the rotor 6 and driving the fan.

In this way, in order to eliminate dead points, we stacked conventional cylindrical field magnets on the rotor in multiple stages, and
The rotor can be manufactured easily and at low cost because a simple structure of notches is sufficient without skewing and combining the joint parts of the poles and N poles.

In addition, if the end face of the field magnet 4 is made to come into contact with the bent piece 9 of the magnetic force line detouring part 8 which is cut out and opened, it will be easier to fix the magnetized field magnet 4 to the rotor hub 5 by adhesive. It is easy to install and work, and the notch functions not only to detour the lines of magnetic force but also to position the rotor when assembling it.

FIGS. 4 and 5 show other embodiments of the present invention, in which a magnetic field line short-circuiting part 10 is provided at the junction of the S and N poles of the field magnet 4 to partially short-circuit the magnetic lines of force to reduce magnetic resistance. It is something. The magnetic field line short circuit part 10 is made by cutting out a predetermined part of the outer periphery of the rotor hub 5, which also serves as a magnetic yoke, and bending the bent piece inward as shown in FIG. These are placed on the end faces of the S-pole and N-pole junctions, respectively.

In this embodiment, a part of the magnetic circuit is short-circuited by an iron piece to reduce magnetic resistance and deflect the magnetic field distribution as desired.

In addition, in this embodiment, the bent piece of the rotor hub not only functions as a short circuit for magnetic lines of force, but also can be used for positioning when attaching the field magnet to the rotor hub in the same manner as described above. .

In this way, in order to eliminate the dead center, it is possible to increase the magnetic resistance partially by detouring the lines of magnetic force as described above, or to increase the number of magnetic forces without making the field magnet a complicated structure that makes manufacturing difficult. This can be easily done by short-circuiting the magnetic resistance to partially reduce the magnetic resistance.The shapes of these openings and short-circuiting pieces are not limited to rectangular shapes, but can also be circular, etc. The shape can be changed as appropriate to make it easier to manufacture.

In the above embodiment, a brushless motor with a 4-pole outer rotor was described, but the brushless motor is not limited to a 4-pole motor, and can be applied not only to an outer rotor motor but also to an inner rotor motor. be.

As described above, the present invention does not require a complicated structure such as skewing and combining the S and N poles of the field magnets of the rotor, and can be attached to a predetermined location on the side surface of the rotor hub. The magnetic field line detour part is cut out and opened, and the side edge of the magnetic field line detour part is bent inward to abut against the end face of the field magnet so that the field magnet can be positioned at a predetermined position on the rotor hub. This makes it easy to eliminate dead points, and the field magnet can be easily attached and fixed to the rotor hub, reducing manufacturing costs and providing a cheaper motor. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted vertical sectional view of an embodiment of the present invention, Fig. 2 is a perspective view of the rotor section of the same, Fig. 3 is a side sectional view of the same, and Figs. 4 and 5 are respectively They are a perspective sectional view and a side sectional view of a rotor part of other examples same as the above. 1... Brushless motor, 4... Field magnet, 6
...Rotor, 8...Magnetic field line detour section, 10...Magnetic field line short-circuit section.

Claims (1)

[Scope of utility model registration request] A side surface of a rotor hub in which a rotor of a field magnet in which S and N poles are arranged alternately is installed is cut out and opened at the junction of the S and N poles to create a magnetic flux detour section. A DC brushless motor characterized in that the side edge of the opening is bent inward and abuts against the end face of the field magnet rotor in order to position the field magnet rotor on the rotor hub.