JPS5915251Y2 - Flat motor - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a flat motor equipped with rotation speed detection means.

Generally, a servo generator is directly connected to the rotating shaft of the motor in order to detect the rotational speed of the motor, but this has the disadvantage that the length in the axial direction is large.

Therefore, in conventional devices, a rotating magnet is mounted inside the motor case, and a detection coil is arranged around the periphery of the magnet to minimize the axial length.

However, a flat motor is characterized by a small axial length, and to take advantage of this point, an electronic governor device is used to maintain a constant speed of the flat motor.

Although this device is independent of the axial length of the motor, it has the disadvantage of low rotational accuracy of the motor.

The present invention has been devised in view of these points, and one embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a first yoke forming a motor case, and a lower opening of the first yoke is covered by a second yoke 2.

An annular magnet 3 magnetized in the axial direction is attached to the inner surface of the second yoke, and a pair of brushes 4.4 are attached in an insulated manner.

Reference numeral 5 includes an armature 6 which is a disk-shaped rotor and is a fixed body of armature windings, a commutator 7 to which the winding bodies of the armature windings are connected, and a rotating shaft 8. 1 2nd yoke 1, 2
It is rotatably supported by oil-less metals 9, 9 attached to.

The above configuration is that of a general flat motor, but in the present invention, a magnetic ring 10 is attached to the periphery of the armature 6.

The magnetic ring has uneven teeth 11 on its outer peripheral surface.

Reference numeral 12 is a magnetic member having concave and convex teeth 13 opposing some of the concave and convex teeth, and is formed in a U-shape, and a coil 14 for detecting the number of revolutions is wound around the middle part thereof.

The lower end 15 of the magnetic member 12 is closely fixed to the second yoke 2, and the upper end 16 is separated from the first yoke 1.

In the above configuration, the main magnetic flux from the magnet 3 flows into the closed magnetic path of the armature 6, the first yoke 1, and the second yoke 2 to rotate the rotor 5, while the leakage magnetic flux from the magnet 3 flows through the closed magnetic path of the armature 6, the first yoke 1, and the second yoke 2. It flows into the closed magnetic path of the magnetic member 12 and the second yoke 2.

At this time, since the magnetic ring 10 is rotating, the double concave and convex teeth 1
The magnitude of the passing leakage magnetic flux changes depending on whether the convex portions of 1.13 oppose each other or when the convex portions and concave portions oppose each other, and an induced voltage is generated in the coil 14.

The frequency is determined by the rotation speed and the number of teeth.

In the embodiment, one magnetic member 12 having a coil 14 is used, but by distributing a plurality of magnetic members, the detection output of the coil can be averaged, and the magnetic ring 10 or the armature 6 It is possible to suppress output fluctuations and frequency fluctuations caused by eccentricity.

As described above, according to the configuration of the present invention, uneven teeth are provided on the outer circumferential surface of the magnetic ring provided on the outer periphery of the disc-shaped rotor, and the magnetic member having the uneven teeth opposing a part of the uneven teeth is Since it is attached to the yoke of the stator magnet that opposes the rotor through an axial gap, leakage magnetic flux from the magnet flows into the magnetic member via the magnetic ring, thereby reducing the coil wound around the magnetic member. The number of rotations can be detected by detecting an induced voltage with a frequency proportional to the number of rotations.

In addition, in this case, there is no need to attach a special magnet to the rotating shaft for detecting the rotation speed, and the advantage of the small axial length, which is a characteristic of flat motors, is not lost. The attachment of the magnetic ring increases the inertia of the rotor, which is preferable for constant speed, and the positioning of the magnetic ring around the outer periphery of the rotor increases the mechanical strength of the rotor.

[Brief explanation of drawings]

The drawing shows one embodiment of the flat motor according to the present invention, and the first
The figure is a sectional view, and FIG. 2 is a partially cutaway perspective view with the yoke removed. 3...Magnet, 5...Rotor, 1
0...Magnetic ring, 11...Concave and convex teeth,
13... uneven teeth, 12... magnetic member,
2... Yoke, 14... Coil.

Claims (1)

[Scope of utility model registration request] A magnetic ring is provided on the outer periphery of a disc-shaped rotor that opposes the stator magnet via an axial gap, and a magnetic member is provided with uneven teeth that partially oppose the uneven teeth provided on the outer peripheral surface of the magnetic ring. A flat motor, characterized in that the number of revolutions is detected using leakage magnetic flux from the magnet with a coil attached to the yoke of the magnet and wound around the magnetic member.