JPH0733585Y2 - Rotary actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rotary actuator having a flat shape in the axial direction of a rotor.

(Prior Art) Conventionally, as an example of a rotary actuator, a so-called axial gap type flat motor having a flat rotor axial direction as shown in FIG. 4 has been known.

This axial air gap type flat motor is axially supported by the stator 2 via a shaft 3 and a substantially disk-shaped stator 2 in which four coils 1 are concentrically arranged, and the permanent surface is opposite to the stator 2. A substantially disk-shaped rotor 5 having a magnet 4 is provided. In this axial gap type flat motor, a current is supplied to the coil 1 and the rotor 5 is rotated by the electromagnetic force generated as a result, and this rotational force is externally output via the shaft 3.

(Problems to be Solved by the Invention) By the way, so-called stepping motors in which a rotor is rotated at predetermined pitches are now widely used in office automation equipment and the like. On the other hand, the place where the stepping motor can be housed in the arrangement space may be limited to, for example, the flat region. As the stepping motors are used more frequently, there are more opportunities to be subjected to such restrictions, and it is considered that the axial gap type flat motors described above are used as the stepping motors as a measure for improvement.

However, in the above-described axial air gap type flat motor, the pole piece of the magnetic material is not provided on the stator 2 side, and the coil 1 is in the air core, so no non-energized self-holding torque is generated, and as a result, It could not be used as a stepping motor.

In order to give a non-energized self-holding torque so that the motor can be used as a stepping motor, it is conceivable to configure the motor as shown in FIG. 5 or FIG. 6 (see Japanese Utility Model Laid-Open No. 61-120245). .

That is, the motor shown in FIG.
12 is formed and the coil 13 is wound around the convex portion 12, while the pole piece 15 is provided so as to protrude toward the rotor core 14 side. Further, in the motor shown in FIG. 6, in order to improve the deviation of the magnetic flux distribution of the rotor core 14 in the motor of FIG. 5, the facing surface 16 of the pole piece 15 located on the rotor core 14 side is substantially wedged. It is formed into a shape. Each of the motors shown in FIGS. 5 and 6 retains the residual magnetism in the pole piece 15 when it is not energized to generate a non-energized self-holding torque for the rotor core 14.

However, in this case, the pole piece 15 is simply provided on the rotor core 14 via the convex portion 12. For this reason,
The non-energized self-holding torque of this motor is shown by the solid line in FIG.
As shown by, changes greatly compared with the target value shown by the broken line 21. As a result, there is a problem in that the rotor core 14 cannot be escaped from the stationary state even if the energization torque is generated by energizing.

The present invention has been made in view of the above circumstances, and can be housed in a flat area, has a proper non-energizing self-holding torque, has the function of a stepping motor, and easily escapes from a stationary state when energized. An object of the present invention is to provide a rotary actuator that can be used.

(Means for Solving the Problems) The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 (A) corresponding to the embodiment. 46 directions are flattened and stator
In the plurality of coils 39 provided on the 70 side, the protrusions 38 extending from the yoke (stator-side magnetic body) 36 are provided with the magnets 48 of the rotor 47.
The pole piece 41, which is inserted into the stator 70 and faces the magnet 48 of the rotor 47 in the stator 70, is connected to each convex portion 38, and is formed to be thinner than the pole piece 41, and the pole piece 41. The auxiliary magnetic path forming member 40 including the bridge portion 42 that connects the two in a ring shape is arranged.

(Operation) According to the present invention, with the above configuration, a part of the magnetic flux passing through the pole piece passes through the bridge portion, that is, the bridge portion serves as a magnetic path for excess magnetic flux, and the non-energized self-holding torque is suppressed to a small value. Easily escape from rest when energized.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a rotary actuator of this embodiment, and 31 is a housing held by a fixture 32. The housing 31 forms a substantially cylindrical shape with the base 33,
And a lid portion 35 which covers the base 33 and forms a cavity portion 34 between the lid portion 35 and the base 33.

A yoke 36 is attached to the lid 35 facing the cavity 34 with bolts 37. The yoke 36 has a substantially disc shape, and four convex portions 38 are formed concentrically. A coil 39 is wound around the convex portion 38, and a magnetic field is generated by supplying an electric current to the coil 39, and this portion constitutes a magnetic pole portion 381.

A substantially donut-shaped auxiliary magnetic path forming member is formed on the lower end surface of the convex portion 38.
40 is fixed with screws. The auxiliary magnetic path forming member 40 is
As shown in FIG. 2A, the bridge portion is provided with four pole pieces 41 having a predetermined thickness fixed to the convex portion 38 and four bridge portions 42 having a thickness t smaller than the pole piece 41. The pole piece 41 is connected at 42 to form a substantially donut shape. In this case, the auxiliary magnetic path forming member 40 is integrally formed. Therefore, the workability is improved as compared with the case where the pole pieces are individually provided, and the assembling can be completed quickly. It should be noted that the present invention is not limited to integrally forming the auxiliary magnetic path forming member 40, and may be a separate body if a magnetic body is used. The connecting portion 43 between the bridge portion 42 and the pole piece 41 is shown in FIG.
As shown in, the curved surface has a radius of curvature R. And
The radius of curvature R is set to three times or more the thickness t of the magnetic member 42. As a result, the pole piece 41 and the bridge portion 42 are gently connected in the magnetic flux distribution, and the torque fluctuation due to the rotation of the rotor 47 (described later) is alleviated.

In the present embodiment, the yoke 36, the convex portion 38, and the coil 39 described above are used.
The stator 70 is constituted by the auxiliary magnetic path forming member 40 and the like.

A thrust bearing 44 is arranged at the center of the yoke 36 having a substantially disc shape, and a metal bearing 45 is arranged in the base 33 so as to face the cavity 35. A non-magnetic shaft 46 is rotatably provided between the thrust bearing 44 and the metal bearing 45. A substantially disk-shaped rotor 47 is attached to the shaft 46 so as to face the yoke 36. The rotor 47 includes a disc-shaped rotor main body 471 fixed to the shaft 46, and a plurality of flat plate-shaped magnets 48 concentrically attached to the rotor main body 471 about the shaft 46. A stopper pin 49 is attached so as to project at a predetermined position on the base 33 side of the rotor body 471. On the other hand, the base 33 at the position corresponding to this stopper pin has about
A 120 ° arc-shaped groove 50 is formed, and the stopper pin 4
At 9, the rotating end of the rotor 47 is positioned.

The base 33 has two output shafts 51 and 52.
Is provided. The output shafts 51, 52 are connected to the shaft 46 via gears, and rotate in association with the rotation of the shaft 46.

In the rotary actuator configured as described above, the coil 39 is sequentially energized to generate a magnetic field in the magnetic pole portion 381 by this energization, and the magnet 48 receives an attractive force by this magnetic field to rotate the rotor 47 in a stepwise manner. Force is output from the output shafts 51 and 52. Then, even if the coil 39 is de-energized and becomes de-energized, by disposing the pole piece 41 in the magnetic pole portion 381,
The residual magnetism is retained in the pole piece 41, and as a result, non-energized self-holding torque is generated. Therefore, it has a function as a stepping motor. On the other hand, a part of the magnetic flux passing through the pole piece 41 leaks to the bridge portion 42. As a result, the non-energized self-holding torque is reduced and the third
As indicated by the solid line 22 in the figure, the variation becomes small, and the variation approximates to the target value indicated by the broken line 20 in FIG. In this way, the fluctuation of the non-energized self-holding torque is suppressed to a small level, so that it is possible to easily escape from the stationary state when energized.

Further, in this embodiment, since the connecting portion 43 between the bridge portion 42 and the pole piece 41 is formed by a curved surface having a radius of curvature R which is three times or more the thickness t, torque fluctuation occurs when the rotor 47 rotates. Also has an effect that the magnetic flux distribution is gradually changed and the torque fluctuation can be alleviated.

Further, in the present embodiment, the non-energized self-holding torque has a characteristic in the upper right direction as shown in FIG. 3 in the vicinity of the rotation angle of 0 degree, so that the rotating operation is stabilized unlike the conventional example shown in FIG. Have.

(Effect of the Invention) Since the present invention is formed in a flat shape in the axial direction of the rotor, it can be housed in a flat area, and is connected to the protrusion of the stator side magnetic body on the magnet side of the rotor of the stator. Since a pole piece is arranged to generate non-energized self-holding torque, it can have the function of a stepping motor. Furthermore, the pole piece is connected in a ring shape with a bridge portion thinner than the pole piece and passes through the pole piece. Since a part of the magnetic flux passes through the bridge portion, the non-energized self-holding torque can be brought close to the target value, and it becomes possible to easily escape from the stationary state when energized.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rotary actuator of an embodiment of the present invention, FIG. 2 (A) is a perspective view showing an auxiliary magnetic path forming member of the rotary actuator, and FIG. 2 (B) is the auxiliary magnetic path. Fig. 3 is a schematic diagram showing the shape of the connecting portion of the forming member, Fig. 3 is a characteristic diagram showing the non-energized self-holding torque of the rotary actuator, and Fig. 4 is a cross section showing an axial gap type flat motor as an example of a conventional rotary actuator. FIG. 5 is a development view showing another conventional rotary actuator, FIG. 6 is a development view showing another conventional rotary actuator, and FIG. 7 is a characteristic view showing non-energized self-holding torque of the rotary actuator. Is. 40 ... Auxiliary magnetic path forming member, 41 ... Pole piece, 42 ... Bridge part, 43 ... Connection part, 47 ... Rotor, 70 ... Stator, 381 ...
Magnetic pole part.

Claims (1)

[Scope of utility model registration request] 1. In a rotary actuator having a flat shape in the axial direction of a rotor, a plurality of coils provided on the stator side are inserted with convex portions extending from a magnetic material on the stator side facing the magnet side of the rotor. An auxiliary magnetic path is formed on the side of the rotor facing the magnet of the rotor, which includes a pole piece connected to each of the convex portions and a bridge portion formed to be thinner than the pole piece and connecting the pole pieces in a ring shape. A rotary actuator in which members are arranged.