JPS6023585B2 - motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved mechanism for preventing static cogging in motors, particularly flat type stormless U-coupled DC motors.

Flat type brushless DC motors have various advantages such as generating large torque, having no torque unevenness, being easy to manufacture, and having a compact shape.For example, they are used in direct drive type record players, etc. ing. FIG. 1 shows an example of such a DC motor, in which 1 is an annular rotor magnet attached to a rotor yoke 2, and rotates around a rotating shaft 3 attached integrally with the rotor yoke. It is supposed to be done. In this case, the rotor magnet 1 has, for example, four poles so that the magnetic flux density becomes sinusoidal. 4 is a bearing, 5 is a bearing housing,
Reference numeral 6 designates a thrust receiver forming a contact portion with the rotating shaft 3, 7 a stator yoke, and 8 a stator winding.

As shown in FIG. 2, the stator winding 8 consists of four coils 8 to 84, each of which has a similar shape and the same winding width, and is made of plastic, for example, as shown in FIG. It was wound around a bobbin 9, and was fixed to the stator yoke 7 by screws 11 through attachment holes 10 provided in the bobbin so as to correspond to the rotor magnets.

For this reason, a screw hole 12 is drilled in the stator yoke 7, but when the rotor magnet 1 rotates, the magnetic resistance changes at this hole, so static cogging as shown in FIG. 4 occurs. It was the cause. This static cogging is one of the causes of uneven rotation of the motor, and deteriorates the performance as a drive motor for the above-mentioned direct drive type record player, tape recorder, etc. The present invention has been made to prevent the occurrence of static cogging in conventional motors. A feature is that holes or protrusions are provided at predetermined positions on the connecting lines to compensate for changes in magnetic resistance.

The present invention will be further explained below with reference to embodiments shown in the drawings. In FIGS. 5 to 7, 13 is a stator yoke 7.
This is a protrusion provided at a predetermined position on a line between the mounting holes 12 of the stator coils 8, to 84 and the motor center point 0 of the stator yoke.

As mentioned above, the stator winding mounting holes 1 are provided in the stator yoke 7.
2 is bored and the bobbin 9 is screwed together with a normally non-ferrous screw 11, the magnetic resistance increases at this hole and causes static cogging. Therefore, in this embodiment, the above-mentioned protrusion 13 is provided, and since this protrusion 3 reduces the magnetic resistance when viewed from the rotor magnet 1 side, it cancels out the increase in magnetic resistance due to the mounting hole 12 and makes it uniform. It can be made into a magnetic resistance.
Note that a hole 14 corresponding to the protrusion 3 is provided in the bobbin 9. Furthermore, when using inexpensive iron pins to attach the rotor windings, the magnetic resistance decreases at the attachment holes, so it is better to provide holes in place of the protrusions in order to counteract this.

Since this hole increases the magnetic resistance when viewed from the side of the rotor magnet 1, it is possible to cancel out the decrease in the magnetic resistance described above and make the magnetic resistance similarly uniform. As explained above, according to the present invention, magnetic resistance can be easily increased by providing projections or holes in a predetermined layer on a line connecting the stator winding mounting holes in the stator yoke and the motor center point of the stator yoke. It is possible to prevent the occurrence of static cogging by absorbing changes in the stator winding, and it is also effective in improving the placement accuracy of the windings by using them to determine the position of the stator windings, especially when protrusions are provided. It is.

In addition to the stator windings, for example, the mounting hole of the Hall element for detecting the rotational position of the rotor magnet can also be made uniform in magnetic resistance as described above.

[Brief explanation of the drawing]

Fig. 4 is a schematic vertical cross-sectional view of a flat type direct current motor without a single coil, Fig. 2 is a diagram showing the lighting arrangement of the stator winding, and Fig. 3 is a configuration diagram of the stator winding. 5 is an explanatory diagram of the occurrence of static cogging, and FIGS. 5 to 7 are diagrams showing an embodiment of the present invention. 7: Stator yoke, 8: Stator winding, 9: Bobbin, 11
: Mounting screw, 12: Mounting hole, 13: Projection or hole. Figure 1 Figure 2 Figure 3 Figure 7 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a motor in which a rotor magnet provided on a rotor yoke and a stator winding attached to the stator yoke using a mounting hole provided in the stator yoke are closely opposed to each other in the direction of the rotation axis, the above-mentioned A motor characterized in that a hole or a protrusion is provided at a predetermined position on a line connecting the motor center point of the stator yoke and the mounting hole to compensate for changes in magnetic resistance caused by the mounting hole.