JPS6245509Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a micromotor with a built-in frequency generator.

Conventionally, micro motors used in micro cassette tape recorders and the like have had to be made as small as possible due to constraints such as miniaturization of the equipment. For this reason, speed control of the motor is performed by bridge control, which does not require a frequency generator. However, due to the demand for improved performance of micromotors, it has been desired to realize a micromotor that can have a built-in frequency generator and can perform highly accurate frequency control while maintaining the conventional dimensions.

FIG. 1 is a sectional view showing a conventional micromotor without a frequency generator, in which the rotation axis A is
Rotor coil B fixed by integral molding of resin on
is arranged opposite to the magnet C that constitutes the magnetic circuit, but the top surface Da of the motor case D
Since it constitutes a magnetic circuit together with the above-mentioned magnet C, it is necessary to have a certain thickness or more to prevent magnetic saturation. However, in order to keep the outer diameter dimension d of the motor as small as possible due to the demand for miniaturization, it is necessary to reduce the thickness of the outer circumferential portion Db of the motor case D, which has little effect on the magnetic circuit. Therefore, in order to manufacture the motor case D, it is first necessary to draw a flat metal plate with the same thickness as the top surface Da into a cup shape using a press, and then cut the inner surface of the outer peripheral portion Db to make it thinner. , the number of steps increases. In the figure, E indicates a yoke constituting a magnetic circuit, F a commutator, and G a brush.

Therefore, the present invention is an attempt to solve the above-mentioned drawbacks, and has developed a micro motor that minimizes the increase in external dimensions of the motor, incorporates a built-in frequency generator, and reduces the number of machining steps. The purpose is to provide.

Hereinafter, the present invention will be explained based on the embodiments shown in the drawings. Fig. 2 is a sectional view of a micromotor according to the invention, and Fig. 3 is a cutaway plan view showing an enlarged main part of the micromotor. .

In the drawings, numerals 1 and 2 are a magnet and a yoke, respectively, which constitute the magnetic circuit of the motor body. 3 is a rotor coil, and the coil 3 is fixed by integral molding of resin to a rotating shaft 6 rotatably supported by bearings 4 and 5, and is opposed to the magnet 1 so as to be rotatable in the horizontal direction. 7 is a commutator fixed to the rotating shaft 6, and 8 is a brush.

Reference numeral 9 denotes a yoke that is used for both the magnetic circuits of the motor body and the frequency generator.
A magnet 11 and a coil 12 for a frequency generator are installed on the upper surface of the yoke 9.

Reference numeral 13 denotes a rotor gear for a frequency generator fixed to the rotating shaft 6, and a predetermined number of tooth profiles 13a are formed at a constant pitch on the outer periphery of the rotor gear. Incidentally, the rotor gear 13 is made of a sintered iron powder material or the like.

On the other hand, the center portion of the top surface portion 10c of the motor case 10 has the same number of claw shapes 1 as the tooth shapes 13a of the rotor gear 13 by cutting downward.
4 is provided facing the tooth profile 13a.

Therefore, the magnet 12 for the frequency generator
The magnetic flux forms a closed loop passing through the top surface 10c of the motor case 10 → the claw 14 → the rotor gear 13 → the yoke 9. Therefore, when the rotor gear 13 rotates due to the rotation of the rotating shaft 6, the magnetic flux density becomes maximum when the tooth profile 13a of the rotor gear 13 and the claw shape 14 match, and the tooth profile 13a and the claw shape 1
4 do not match, the magnetic flux density becomes the minimum, and the reluctance of the magnetic circuit for the frequency generator changes due to the rotation of the rotor gear 13.
Yoke 9 in which coil 12 for frequency generator is arranged
The magnetic flux between the top surface portion 10c and the top surface portion 10c also changes. As a result,
Pulses with a frequency proportional to the number of rotations of the rotor gear 13 and the number of teeth 13a and pawls 14 are extracted from the coil 12, thereby controlling the speed of the motor. Incidentally, the above-mentioned yoke 9 serves also as the magnetic circuit of the motor body together with the magnet 1 and yoke 2.

As mentioned above, the present invention is a micromotor in which a rotor coil 3 is rotatably arranged opposite to a magnet 1 constituting a magnetic circuit of the motor body, and a frequency generator is connected to the motor body opposite to the rotor coil 3. Yoke 9 that constitutes both magnetic circuits of the machine
and the yoke 9 and the motor case 1.
A magnet 11 and a coil 12 for a frequency generator are installed between the rotor coil 3 and the top surface 10c of the rotor coil 3.
fixing the rotor gear 13 for a frequency generator having a
The same number of pawl shapes 14 as the tooth profile 13a of the rotor gear 13 are arranged opposite to the tooth profile 13a. Therefore, motor case 1
By incorporating a frequency generator into the motor, highly accurate frequency control becomes possible, and the only increase in external dimensions of the motor due to the built-in frequency generator is the total thickness of both the yoke 9 and the magnet 11. , the size increase is small, and it is suitable for the demand for miniaturization. Furthermore, since the yoke 9 that constitutes both the magnetic circuits of the motor body and the frequency generator is used, there is no need to make the top surface portion 10c of the motor case 10 particularly thick.
A flat metal plate having the same thickness as the above can be immediately formed by press molding, and post-processing such as cutting after molding is not required, so the number of steps can be reduced accordingly. Furthermore, when assembling the motor, the process is the same as the conventional motor assembly process except for inserting the frequency generator magnet 11 and coil 12 into the motor case 10 and press-fitting the yoke 9, so there is no need to change the production process. Very few.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional micromotor, FIG. 2 is a sectional view of a micromotor according to the present invention, and FIG. 3 is an enlarged cutaway plan view of the main parts of the motor. 1... Magnet, 2... Yoke, 3... Rotor coil, 6... Rotating shaft, 9... Yoke, 10...
...Motor case, 10a...Outer periphery, 10c...
Top part, 11... Magnet, 12... Coil,
13...Rotor gear, 13a...Tooth profile, 14...
Claw shape.

Claims (1)

[Scope of utility model registration request] In a micromotor in which a rotor coil is rotatably arranged opposite to a magnet which constitutes a magnetic circuit of the motor body, a yoke which constitutes both the magnetic circuits of the motor body and a frequency generator is arranged opposite to the rotor coil. At the same time, a magnet and a coil for a frequency generator are installed between the yoke and the top surface of the motor case, and a rotor gear for the frequency generator having a predetermined number of teeth on the outer periphery is fixed to the rotating shaft of the rotor coil. At the same time, the top surface of the motor case is cut and raised, and the same number of pawl shapes as the tooth profile of the rotor gear are arranged opposite to the tooth profile.