JPS62236346A - Servo motor - Google Patents

Abstract

PURPOSE:To simplify the structure and a control circuit for a servo motor by making the closed loop of a servo motor magnetic flux perpendicularly cross a motor rotating plane to always maintain the direction of the magnetic flux to a coil constant at motor rotating time. CONSTITUTION:The stator of a motor is composed of permanent magnets 1a, 1b and a stator yoke 2. The magnet 1a is magnetized at N-pole at the outer peripheral side and at S-pole at the inner peripheral side in an annular shape. The magnet 1b is magnetized at S-pole at the outer peripheral side and at N-pole at the inner peripheral side in the same shape as the magnet 1a. A rotor is composed of a rotor yoke 3 and a coil 4. A plurality of slots are formed on the outer periphery of the yoke 3, and the coil 4 is wound in the slot on the inner peripheral surface of the yoke 3. Gaps between the coil 4 and the magnets 1a, 1b are constant. The winding directions of the coils 4 are reverse in the winding directions on the magnets 1a and 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to servo motors, and particularly to direct drive servo motors that do not require a commutator.

[Conventional technology]

Conventional direct drive servo motors that do not require a commutator include various types such as brushless induction servo motors, synchronous drive type brushless servo motors, and retactance type pulse motors.

All of these motors are configured to operate by sequentially switching the magnetic poles within the rotation plane of the motor.

Therefore, in conventional direct drive motors, a loop of magnetic flux is formed within the rotational plane of the motor, and for example, in the case of brushless induction servo motors, vector control is required, resulting in a complicated control circuit. There is. Furthermore, in the case of a synchronous drive type brushless servo motor, a magnetic pole detection mechanism such as a Hall element and a circuit for switching the coils are required, and the structure is complicated and the drive circuit is also expensive.

Furthermore, reluctance type pulse motors have performance problems such as inferior acceleration/deceleration characteristics and large torque ripples (minor fluctuations in torque) compared to other types of servo motors.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention, in other words, the purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional servo motor, and to reduce the cost because the structure is simple and the control circuit or drive circuit is simple. The object of the present invention is to provide a servo motor that is inexpensive and has superior performance in terms of acceleration/deceleration characteristics, torque ripple, and the like.

[Means for solving problems]

6 The servo motor of the present invention has an outer circumferential side as a north pole and an inner circumferential side as a north pole.
“ A first permanent magnet in the form of an annular ring whose side is magnetized to S pole, and a second permanent magnet having the same shape as the first permanent magnet whose outer circumferential side is magnetized to S pole and inner circumferential side is magnetized to N pole. , a first yoke that arranges the first permanent magnet and the second permanent magnet in parallel and fixes them to the outer periphery; and a first yoke that is arranged outside the first and second permanent magnets with a certain gap between them. a second yoke, the second yoke having a plurality of slots with equal circumferential angles on its outer circumferential side, and a plurality of slots at positions corresponding to each of the first permanent magnet and the second permanent magnet. a through hole penetrating the slot and an inner circumferential surface, and a coil wound around the slot, the through hole, and the inner circumferential surface, the winding direction of the coil being relative to the first permanent magnet. The winding direction and the winding direction of the second permanent magnet are opposite to each other.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a detailed view of part B, and FIG. 3 is a sectional view taken along line A-A.

1 to 3, the starter of the motor is composed of permanent magnets 1a and 1b and a starter yoke 2. As shown in FIGS. The permanent magnet 1a has an annular (ring-shaped) shape, with the outer circumferential side being magnetized to the north pole and the inner circumferential side being magnetized to the south pole. Further, the permanent magnet 1b has the same shape as the permanent magnet 1a, with the outer circumferential side being magnetized with Si and the inner circumferential side being magnetized with N pole. These two permanent magnets 1a and 1b are arranged and fixed in the axial direction on the outer periphery of the annular stator yoke 2.

On the other hand, the rotor of the motor has a rotor yoke 3 and a coil 4.
It consists of The rotor yoke 3 is arranged concentrically outside the permanent magnets 1a and 1b with a constant gap maintained therebetween. A plurality of slots 5 are provided on the outer circumference of the rotor yoke 3 and arranged at equal circumferential angles, and a through hole 7 is provided between each slot and the inner circumferential surface of the rotor yoke 3. The coil 4 is wound around the slot 5, the through hole 7, and the inner peripheral surface of the rotor yoke 3, and the gaps between the coil 4 and the permanent magnets 1a and 1b are constant. The winding direction of the coil 4 is such that the winding direction around the permanent magnet 1a and the winding direction around the permanent magnet 1b are opposite to each other.

Next, we will discuss the operation of the embodiment configured as described above.
This will be explained with reference to the figures and FIG.

In FIG. 2, the magnetic flux 6 emitted from the N pole of the permanent magnet 1a passes through the coil 4 in the air gap and enters the part 3 of the rotor yoke 3 facing the permanent magnet 1a, but the coil 4 in the slot 5 of the rotor yoke 3 Rotor yoke 3 without penetrating
Proceed perpendicularly to the paper inside (indicated by the symbol ■ in Figure 2)
As shown in FIG. 3, a closed loop of magnetic flux 6 is formed from the permanent magnet 1b through the stator yoke 2 by passing through the coil 4 wound in the gap through the part facing the permanent magnet 1b. This closed loop of magnetic flux 6 is configured to be orthogonal to the rotational surface of the motor (parallel to the rotational axis).

In order to rotate the motor in a predetermined direction, current may be passed through the coil 4 in a predetermined direction. The current flowing through the coil and the magnetic flux 6 crossing it generate a force in a predetermined direction based on Fleming's left-hand rule, thereby rotating the rotor yoke 3 and coil 4 that constitute the rotor. Further, positioning control for positioning can be easily performed by adding a position detection sensor to configure a servo system and applying a control current. Note that when power is supplied to the coil 4 by cable wiring, the cable rotates together with the rotor, so it is best to use it as a direct drive motor within a small rotation angle range.

〔Effect of the invention〕

As explained in detail above, since the servo motor of the present invention has a closed loop of magnetic flux perpendicular to the motor rotation surface, the direction of the magnetic flux to the coil is always constant during rotation of the motor. Therefore, there is no need to provide a commutator in the motor itself, and it can be driven by a general brush type servo motor drive device, and the structure is simple, which has the effect of reducing costs. Furthermore, since the size of the gap that generates the rotational force of the motor is constant over the entire area, the torque ripple is theoretically small and the servo control characteristics are excellent.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
A cross-sectional view showing details of part B in the figure, Figure 3 is taken along line A-A in Figure 1.
FIG. la, lb...Permanent magnet, 2...Stator yoke,
3... Rotor yoke, 4... Coil, 5... Slot, 6... Magnetic flux. ζ′ Ni・′−? Pa・su()′! ...-Representative Patent Attorney Susumu Uchihara- //11: Water magnet 2: Also theta yoke 3: U-y yoke 4: Coil grass/Figure O:, m water: Slot. Kaya 2y! Jf;Jv! J

Claims (1)

[Claims] An annular first permanent magnet with the outer circumference side magnetized as N pole and the inner circumference side as S pole, and the same shape as the first permanent magnet with outer circumference side magnetized as S pole and inner circumference side as N pole. a second permanent magnet; a first yoke that arranges the first permanent magnet and the second permanent magnet in parallel and fixes them on the outer periphery thereof; and a second yoke disposed with a certain gap therebetween, and the second yoke has a plurality of slots with equal circumferential angles on its outer circumferential side and a plurality of slots between the first permanent magnet and the second permanent magnet. a through hole penetrating the slot and the inner circumferential surface at a corresponding position, and a coil wound around the slot, the through hole, and the inner circumferential surface, and the winding direction of the coil is A servo motor characterized in that the winding direction of the first permanent magnet and the winding direction of the second permanent magnet are opposite to each other.