JPH0428217Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an electric motor equipped with a pulse generator (hereinafter abbreviated as PG).

FIG. 1a shows a conventional motor with a PG.This motor connects a rotor yoke 1 which is in contact with one end face of a flat annular permanent magnet 2 to a rotor shaft 4 via a rotor hub 3. The rotor shaft 4 is rotatably supported by a fixed bearing bracket 5 through a bearing 6, and an insulating plate 9 disposed opposite to the permanent magnet 2 with a gap is fixed to the bearing bracket 5. Moreover, a plurality of stator windings 8 are mounted on this insulating plate 9.
has been set up. Further, a pulse generating winding 10 is provided on the insulating plate 9, and this pulse generating winding 10 faces small pulse generating magnets 11 and 11' provided on the outer periphery of the rotor yoke 1 with an appropriate gap in between. It's like that.

The conventional electric motor shown in FIG. 1A uses a magnetic detector (not shown) to detect the magnetic flux of a permanent magnet 2 facing a plurality of stator windings 8, The rotor yoke 1 equipped with a permanent magnet 2 is driven in a fixed direction by sequentially energizing each stator winding 8. For example, the rotor yoke 1 is used for driving a drum equipped with a magnetic head of a VTR. Used as an electric motor.

When used as a motor for such a drum, one pulse is generated every 1/2 rotation of the rotor yoke 1, and the polarity of the generated pulse changes every 180 degrees as shown in Figure 1c. It is necessary that the polarity be reversed, and for this reason, the small pulse generating magnets 11 and 11' are located on the outer periphery of the rotor yoke 1 symmetrically with respect to the axis, and their polarities are N and S poles. It is installed like this.

As a result, the pulse generating winding 1 provided on the insulating plate 9
0, when the rotor yoke 1 rotates and faces the small magnets 11, 11' provided on the outer periphery of the rotor yoke 1, a pulse is generated, and the polarity is 180 as shown in FIG. It becomes positive and negative for each degree, and the position of the rotor yoke 1 is detected every 180 degrees. Therefore, the mounting positions and polarities of the small magnets 11, 11' are important, and in particular, they must be at positions 180 degrees different from each other and must have different polarities from the north and south poles. For this reason, in the past, the polarities of the small magnets 11 and 11' were determined and each was attached to the outer periphery of the rotor yoke 1 one by one, but advanced technology was required to get the mounting position and polarity correct. It was.

The purpose of the present invention is to obtain a PG-equipped electric motor that solves the above-mentioned problems in the prior art.

Another object of the present invention is to provide a motor with a PG in which the small magnet for the PG is formed integrally on a ring instead of a single unit, thereby making it easier to attach the small magnet.

The electric motor with a pulse generator of the present invention includes a rotor consisting of a yoke with a flat annular permanent magnet in contact with one end face fixed to the rotor shaft, and a rotor that is disposed opposite to the rotor with an air gap interposed therebetween. It consists of a plurality of stator windings, a pulse generating winding, and a ring made of plastic magnet material fitted around the outer circumference of the rotor. A feature is that the protrusions are integrally formed, and the protrusions are magnetized with opposite polarities.

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

Figure 2a shows the electric motor with PG according to the present invention.
The same parts as in FIG. 1a are given the same reference numerals, and their explanation will be omitted.

In this invention, the small magnet for PG is not used as a single unit,
Small magnets 21 and 21' for PG are integrally formed on the outer periphery of a thin ring 20 of plastic magnet material fitted to the outer periphery of a permanent magnet 2 attached to a rotor yoke 1, protruding at 180 degrees.

Since the electric motor with PG according to the present invention has the above-mentioned configuration, the placement positions of the small magnets 21, 21' are always determined by the mold, and the portions of the ring 20 corresponding to the small magnets are diametrically N-pole and S-pole. If you magnetize them, you can always magnetize them with alternating polarities. Moreover, such a ring 20 can be easily and integrally fixed to the outer circumference of the permanent magnet 2 by fitting it thereto.

In addition, the ring 2 provided with the small magnets 21 and 21'
0 may be provided on the outer periphery of the rotor yoke 1 instead of fitting on the outer periphery of the permanent magnet 2.

[Brief explanation of the drawing]

Figure 1a is a longitudinal cross-sectional view of a conventional electric motor with PG, Figure 1b is an explanatory plan view thereof, Figure 1c is an explanatory diagram of the generated pulses, and Figure 2a is a longitudinal cross-section of the electric motor with PG of the present invention. FIG. 2b is an explanatory plan view of the small pulse generating magnet, and FIG. 2c is a longitudinal sectional view thereof. 1...Rotor yoke, 2...Permanent magnet, 3...
Rotor hub, 4... Rotor shaft, 5... Bearing bracket, 6... Bearing, 8... Stator winding, 9... Insulating plate, 10... Pulse generating winding, 11, 11'...
...Small magnet, 20...Ring, 21, 21'...Small magnet.

Claims (1)

[Scope of utility model registration request] A rotor consisting of a yoke with a flat annular permanent magnet in contact with one end face fixed to the rotor shaft, a plurality of stator windings disposed opposite to this rotor with a gap in between, and a pulse generator. It consists of a generating winding and a ring made of plastic magnet material fitted around the outer periphery of the rotor.
An electric motor with a pulse generator, characterized in that protrusions are integrally formed at positions separated from each other by 180 degrees, and the protrusions are magnetized with opposite polarities.