JPS6116785Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor of a flat DC motor equipped with an encoder for detecting the rotational position of the rotor.

DC motors that use iron-free rotors have a lightweight rotor and low inertia, so they have excellent time constant characteristics during start-up and stop, so they are used in office machines,
In recent years, it has been widely used for servo mechanisms such as computer peripheral equipment. Some of these coreless rotors have a hollow cylindrical shape, some have a disk shape, and some have a rotor in which the outermost peripheral part of the disk protrudes along the motor shaft. Regardless of which rotor is used, this type of DC motor is used,
For example, in order to perform positioning control such as character selection in single-element printers and electric typewriters, which are office machines, a separate encoder is provided outside the motor and directly connected to the rotor shaft.

Installing this encoder required extremely high precision, and required a great deal of time, manpower, and expense to manufacture and install the encoder.
Furthermore, in order to solve the drawbacks of these DC motors, pulse motors have been increasingly used in recent years. To some extent, pulse motors can start and stop the rotor at any number of divisions without an encoder, but their self-starting frequency is low, making it difficult to select and stop type at high speed. Furthermore, the processing and assembly of pulse motors requires extremely high precision, leading to high costs for the motors.

In view of the above-mentioned conventional drawbacks, the purpose of the present invention is to integrally mold an encoder for detecting the position of the rotor relative to the stator on the peripheral edge of the rotor using resin molding, thereby hardly changing the inertia of the rotor. In addition to creating a shape suitable for mass production, by providing several through holes for heat insulation between the coreless coil and the encoder section, the encoder section will not be deformed due to the heat generated in the coreless coil section. To provide a rotor for a flat type DC motor with an encoder that prevents a decrease in detection accuracy.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a rotor showing an embodiment of the present invention. In this rotor 1, three coils 2
are formed by molding with resin 3 at an angle of 120 degrees to each other within one plane. As this resin 3, modified poly, butylene, or terephthalate, which has excellent heat resistance and moldability and has a relatively low specific gravity, is used. The center of the coil 2 is hollow. At the time of molding, a plurality of notches 4 are formed on the outer periphery of the resin part 3 to form an uneven part 5, and three through holes 6 for heat insulation are formed in the resin part between each coil 2 and the uneven part 5.
are formed and these together with the commutator 7 are integrally molded onto the rotor shaft 8. This uneven portion 5 is provided to an encoder. Incidentally, among the six commutators 7, the commutators 7 located at symmetrical positions with respect to the rotor axis 8 are in a state of conduction with each other.

Next, an embodiment of the mounting structure for the rotor 1 will be described with reference to FIGS. 2 and 3.

The bearing metals 20 and 21 are attached to the upper bracket 22,
They are respectively press-fitted and held in the lower bracket 23. Further, the upper and lower brackets 22 and 23 are formed by pressing or the like, and are fitted at their outer peripheries by a method such as caulking. In addition, the upper and lower brackets 22 and 23 are similar to the lower bracket 2.
The permanent magnets 24 fixed at positions facing the coils 2 of No. 3 also attract and hold each other. This permanent magnet 24 constitutes the stator of the motor. The upper and lower brackets 22 and 23 are provided with through holes 27 and 28 for inserting and holding a light source 25 formed by a light emitting diode and a light receiving element 26, respectively. The two brushes 29 are fitted and held at an angle of 90 degrees to each other in the upper bracket 22, and a power supply conductor 30 is led out from there.

In the motor configured as described above, when power is supplied to the coil 2 via the brush 30 and the commutator 7, the rotor 1 rotates, but as the rotor 1 rotates, the light irradiated from the light source 25 to the light receiving element 26 changes periodically. The signal is photoelectrically converted by the light receiving element 26. Here, the light source 25 and the light receiving element 2
Reference numeral 6 is located at a position opposite to the uneven portion 5 for the encoder, and is used to indicate the rotational position of the rotor.

As detailed above, in this embodiment, the uneven portion 5 for the encoder, the through hole 6, the coil 2, the commutator 7, and the rotor shaft 8 are integrally formed by resin molding, so the encoder is not attached to the motor separately. It is possible to omit various troubles for attaching the encoder to the encoder, and the through hole 6 blocks the heat generated in the coil 2 from being conducted to the uneven portion 5 for the encoder, thereby suppressing thermal deformation of the uneven portion 5. Accuracy can be maintained sufficiently even when the motor is used continuously.

In this embodiment, the through hole 6 was used only for heat insulation, but it is also possible to provide a pair of light sources and a light receiving element at positions facing the through hole 6 and use it to switch the excitation phase of the coil 2. It is.

As described above, the present invention can provide a rotor for a flat type DC motor with an encoder that has a high precision encoder and is suitable for mass production, and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a rotor for explaining an embodiment of the present invention, FIG. 2 is a cross-sectional view of a flat DC motor having the rotor, and FIG. 3 is an enlarged cross-sectional view taken along the line -1. In the figure, 2 is a coil, 3 is a resin part, 5 is an uneven part for an encoder, and 6 is a through hole.

Claims (1)

[Claims for Utility Model Registration] In a rotor comprising a coreless coil arranged in one plane by resin molding and an encoder section provided at the peripheral edge, there is provided heat insulation between the coreless coil and the encoder section. 1. A rotor for a flat type DC motor with an encoder, characterized in that a plurality of through holes are provided for use in the rotor.