JPS6130927A - Small-sized dc motor - Google Patents

Abstract

PURPOSE:To suppress the generation of an eddy current by correspondingly disposing a rotor magnet and a magnetic yoke at both sides of a drive coil, and spirally or concentrically winding a magnetic material on the yoke. CONSTITUTION:A rotor frame 14 is mounted on a rotor shaft 13, and a rotor magnet 15 is secured to the lower surface of the frame 14. A drive coil 17 is provided through a magnetic yoke 16 on a substrate 11. The yoke 16 is constructed by winding spirally or concentrically a magnetic material 18 coated with an adhesive 19 on one side. Thus, the thickness is reduced to suppress the eddy current to improve the efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a small DC motor used in small devices such as portable cassette recorders and cameras.

Conventional configuration and its problems Conventionally, as a means for preventing eddy current in this type of small motor, for an axial gap type AC motor, the method shown in Fig. 4B is used.
A thin iron plate 1 with winding slots 2 as shown in FIG. 4 is rolled and hardened to form an iron core to prevent the generation of eddy currents. In addition, as shown in FIG. 2, in an axis-perpendicular gap type DC motor, a stator 6 having a winding 5 attached to the outer periphery of a bearing 4 attached to a base plate 3 is fixed to a rotor frame 8 attached to a shaft 7. A rotor magnet 9 is provided, and the stator 6 has a structure in which thin iron plates are laminated to prevent the generation of eddy currents.

Also, with the miniaturization of equipment, small DC motors have come into widespread use in recent years, but their general structure is as shown in FIG.
is fixed to the rotor shaft 7, and a rotor frame 8 and a rotor magnet 9 attached to the rotor frame 8 are configured as a thin axial gap type motor that rotates. At this time, the substrate 3 is a magnetic material that constitutes a magnetic circuit, and the magnetic flux generated in the rotor magnet 9 attached to the rotor frame 8 passes through the coil 10 and reaches the substrate 3 that constitutes the magnetic circuit. 3 is different from the above-mentioned figures 4 and 6.
It is common to use a single plate to make the motor thinner.

In this case, the rotor magnet 9 attached to the rotor shaft also rotates, but this rotation generates eddy currents in the substrate 3, which generate heat instead of rotational torque, reducing the efficiency of the motor. . In this case, even if the board is composed of laminated iron plates, the lamination direction differs by 900 degrees with respect to the magnetic flux emitted from the rotor magnet 9, so that no effect of preventing eddy currents can be obtained. That is, the motors with the structures shown in FIGS. 1 and 2 were used as relatively thin motors that did not require any use, and the motors with the structure shown in FIG. 3 were miniaturized and used without any measures to prevent eddy currents.

OBJECTS OF THE INVENTION The present invention provides a highly efficient DC motor that has a shape that can accommodate downsizing and thinning of equipment, and has a structure that takes measures against eddy currents.

Structure of the Invention In order to achieve this object, the present invention arranges a rotor magnet and a magnetic yoke in correspondence with a drive coil in between, and constructs the magnetic yoke by winding a magnetic material in a helical or concentric manner. This results in a thin motor that suppresses the occurrence of.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. As shown in the figure, a rotor shaft 13 is fitted into a bearing 12 fixed to a substrate 11.
3, a rotor frame 14 is attached to the rotor frame 14, and a rotor magnet 16 is further fixed to the lower surface of the rotor frame 14. Further, the substrate 11 is equipped with a drive coil 17 via a magnetic yoke 16 . The magnetic yoke 16 is
The adhesive 19 is applied to one side of the magnetic material 18.
The magnetic yoke 16 is wound spirally or concentrically as shown in the figure, and the magnetic yoke 16 is adhesively fixed onto the substrate 11 as shown in FIG.
Furthermore, a drive coil 17 is fixed on this magnetic yoke 1e to constitute a motor. Note that the magnetic yoke 1e is not necessarily fixed on the substrate 11, and the substrate 11 may be omitted. In addition, this type of motor can be used as a motor for ultra-thin cassette recorders, and can be used to make OA equipment smaller and thinner, such as spindle motors for floppy disks.

Effects of the Invention As described above, according to the present invention, it is possible to reduce the thickness, suppress the generation of eddy currents, and improve efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a small motor according to an embodiment of the present invention, FIG. 2 is a perspective view of a magnetic yoke used in the motor, and FIG.
The figure is a sectional view of the same, Figures 4A and B are perspective views of the iron core used in an axial gap type AC motor, and a perspective view before the core is formed, and Figure 5 is a perspective view of a conventional axial gap type AC motor. FIG. 6 is a sectional view of a conventional axial gap type DC motor. 16... Rotor magnet, 16... Magnetic yoke, 17... Drive coil. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 N Figure 2 Figure 3 C

Claims (1)

[Claims] A small DC motor in which a rotor magnet and a magnetic yoke are arranged in correspondence with a drive coil in between, and the magnetic yoke is constructed by winding a linear magnetic material in a spiral or concentric manner.