JPS5996862A - Stepping motor - Google Patents

Abstract

PURPOSE:To reduce an overshoot of a stepping motor at the stopping time with a simple structure and to smoothly and reliably restart the motor by adding a frictional load of a thrust direction to a rotor to reduce part of an output torque. CONSTITUTION:A rotor 6 is disposed in a space 7 which is surrounded by a coil 5 mounted on a pole 2. Both ends of a rotational shaft 12 which passes through the center of the rotor 6 are respectively maintained by bearings 13, 14. A damping unit 23 which is secured to a holder 24 is pressure contacted with one end face of the rotor 6, and a thrust direction frictional load is added by a damping unit 23 to the rotor 6. The inertia of the rotor 6 is suppressed by the unit 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a stepping motor, and relates to a configuration that reduces rotor overshoot and accelerates damping.

[Technical background of the invention and its problems] Generally, in this type of stepping motor, the rotor is rotated at each stitch angle by alternately exciting the coils, and a predetermined rotation angle is obtained at a predetermined synchronous speed. It looks like this.

However, in a stepping motor, the generated torque changes depending on the position of the rotor, and speed fluctuations occur depending on the inertia of the rotor and load, and friction torque.

It also responds excessively when stopped and vibrates before damping and stopping. For example, as shown in Figure 8, it is accelerated until it reaches the first target step angle, decelerated when it exceeds that target step angle, and then when the next step person caballus enters, the target step angle moves to the next step. The rotor is then accelerated again. The rotor is accelerated and decelerated each time the step angle advances, and is rotated by a predetermined number of step angles.

When the rotor stops rotating, the rotor greatly overshoots and is pulled in the reverse direction by the pullback torque, and then overshoots in the opposite direction, and then rotates in the forward direction again, alternating between the forward and reverse directions. It rotates back and forth, is gradually damped by the load resistance, and then stopped. If this rotor is started again while it is rotating significantly in the reverse direction, the rotational force will be insufficient due to the inertia force in the reverse direction, and it will not be able to follow the synchronous speed, resulting in a step-out condition and the motor will stop. There were times when I ended up doing this. Especially when stopping and restarting every few step angles, step-out phenomenon is likely to occur.
Furthermore, even when rotating continuously, there is a risk of resonance with the output side and loss of synchronization.

For this reason, a method of applying a friction load to the rotating shaft of the rotor to prevent inertia from occurring in the rotor can be considered, but if a friction load is applied from the radial direction of the rotating shaft using a brake shoe, the brake shoe will be deflected. Resonance is likely to occur, causing step-out, and since the rotating shaft has a small diameter, it has the drawback of requiring a large force to press into contact with the rotating shaft such as a brake shoe. Furthermore, if a brake shoe is used to attach a boob to the rotating shaft, the pressure contact force can be reduced, but rotor inertia increases and the maximum response frequency decreases.

It is also possible to apply a brake to the rotating shaft by installing a resistance plate with a submerged trap on the rotating shaft, but this method requires a large device and cannot be installed inside the motor, which is an obstacle to miniaturization. There is next door.

[Purpose of the invention]

The present invention has been developed in view of the above drawbacks, and provides a stepping system that has a simple configuration for the rotor, reduces overshoot when the rotor is stopped, speeds up damping, smoothly and reliably restarts the rotor, and can be made compact. It provides motors.

[Summary of the invention]

The stepping motor of the present invention includes a stator core in which a plurality of balls having a plurality of convex portions corresponding to step angles are protruded inward, and a stator core that is fitted into each of the balls and disposed inside the core. a plurality of coils; a rotor disposed in an inner space of the core surrounded by the coils; and a rotor having a protrusion formed on a peripheral surface according to a step angle corresponding to a protrusion of the ball; and the core. a damping body disposed in the inner space of the rotor and applying a friction load to the rotor in the thrust direction to reduce a part of the output torque;
This reduces a portion of the output torque of the motor to reduce overshoot and speed up damping.

[Embodiments of the invention]

Next, the configuration of an embodiment of the present invention will be explained with reference to the drawings>1 to 6.

(1) is a laminated or integrally molded stator core, which is formed into a rectangular shape with a substantially square frame shape, and a ball (2) is protruded from the center of the inner path of each side, and a plurality of balls (2) are attached to the tip of the ball (2). A convex portion (3) is formed.

Further, (4) is a bobbin around which a coil (5) is wound, which is fitted and attached to each ball (2) of the core (1).

Then, the opposite two sides of the balls (2) are bifilar-wound with human phase and phase input coils.
B-phase and i-phase coils are wound around the ball (2) on the side using bifilar winding.

Next, (6) is a rotor, which is arranged in a space (7) surrounded by coils (5) attached to each ball (2), and this rotor (6) is equipped with a disk-shaped permanent magnet ( A disk-shaped magnetic body (91 (1G) is provided on both sides of the QOI, and protrusions a9 are formed at equal intervals on the outer circumferential surface of the QOI, and the upper and lower magnetic bodies (Convex portion αB of (91(if))
are circumferentially offset from each other by one-half of the step angle.

In addition, bearings ([31 (141)
are respectively provided, and the bearings a3←4 are maintained at a distance from the rotor α by a locking ring 09 provided on the rotating shaft Q'IJ.

Further, a printed wiring board αe is provided to each bobbin (4) to connect the lead wire of the coil (5). Further, this wiring board (16) is provided with a connector (171).

Next ←8 (19 is the motor frame, this frame is exposed a
! J is fitted onto both end surfaces of the core (1). The inner surface of each motor frame (181←l has an annular edge Q into which the bearing (13) α is fitted concentrically with the through hole QC through which the rotational shaft α2 is inserted.
fJ is formed. The outer race (13a) of this one bearing (13) is attached to a spring washer (
At (b), it is preloaded toward the rotor (6) and comes into contact with the locking ring a9.

Further, (c) is a damping body, which is formed of an annular plate made of an elastic material such as rubber, plastic, cloth material, metal material, etc., and is fixed to the holding body (goods) with adhesive or the like. This holding body C)4) has, for example, four damping legs protruding from the outer peripheral edge at equal intervals toward the side opposite to the fixed surface of the damping member 231.

The rotation stopper leg (c) of this holder (241) is fitted to the outer periphery of the annular edge (21) of the one motor frame (a) so as to be slidable in the axial direction, and The holding body (to) is prevented from rotating by engaging with the protrusion or groove (a).

Moreover, a spring washer (2η) is pressed against one end surface side of the rotor (6) between the inner end of this holder (2a is the annular edge 01) and this holder C4), and the holder (24) The damping body (c) fixed to the rotor (6) is pressed against one end face of the rotor (6), so that the damping body (2) applies a friction load to the rotor (6) in the thrust direction. It has become.

Note that the protrusion or groove (c) formed on the annular edge C of the motor frame (2) that locks the rotation stopper leg (c) of the holding body (goods) is positioned approximately diagonally of the core (1) to prevent rotation. The leg (C) is arranged in a space between the coil (5) and the rotor (6).

And the motor frame Qa (
Reference numeral 19 fixes a bolt (not shown) through the insertion hole (c).

Next, the operation of this embodiment will be explained.

By alternately exciting the coil (5) attached to each ball (2) of the core (1), each ball (2) becomes an N pole and an S pole alternately, and the magnetic body (9) of the rotor (6) (10)
The convex portion (10) of is attracted, the rotor (6) rotates at a step angle of 00, and when the excitation of the coil (5) is sequentially switched, the rotor (6) is rotated at every step angle θ0. A damping body r2 is provided on one end face of the rotor (6).
31 is in frictional contact with the elastic force of the spring washer 07), the output torque of the motor is reduced, and the rotor (6)
The inertia is suppressed when the rotor (6) is stopped, there is little overshoot, the damping is accelerated, and the amount of rotation in the reverse direction is small. ) is rotated, and there is a possibility of losing synchronization.
・.

In addition, even when rotating at multiple step angles, the inertia between each step angle is suppressed, so the rotation follows the synchronous speed and there is no chance of step-out.

Next, the stepping motor shown in the above embodiment and a conventional stepping motor without an integrated damper.

I will explain the experimental results of 7 figures and 8 figures.

The off-line diagram is a dynamic characteristic diagram of a stepping motor shown in an embodiment of the present invention, and is a result of intermittent driving of a 24V motor with a winding resistance of 6Ω, chopper drive at 600 pps, and 6 pulses resting for a certain period of time, then restarting, and approximately 10j'. An inertial load of cm is attached. Detent torque including friction load due to damping body is 2.QO to 210t-α
So, when the friction load is removed, the detent torque is 1
20 to 150 f-cm and the motor torque without frictional resistance was 600 PPS and 1 pull-in torque of 300 to 350 r.α.

Further, Fig. 8 shows the characteristics measured under the same conditions as those of the conventional stepping motor without a damping body.

As is clear from this characteristic diagram, the internal cause of overshoot when stopping at 6 step angles due to 5 to 6 pulses is approximately 1/2 or less than K due to applying a sliding load to the rotor (6) with the damping body @. It was confirmed that the attenuation becomes faster.

Although the above experimental example uses a chopper drive method, similar results were obtained using a drive method using an external resistor.

In the above embodiments, a hybrid stepping motor has been described, but the present invention is not limited to the hybrid stepping motor and can be applied to various stepping motors.

〔Effect of the invention〕

According to the present invention, since a friction load is applied to the rotor in the thrust direction by the damping body in order to reduce the output torque of the motor, the inertia of the rotor is suppressed, so there is less overshoot due to inertia when stopping. , the damping is performed quickly, and even if the motor is subsequently restarted, there is no shortage of rotational torque due to resonance, and the motor rotates smoothly and follows the synchronous speed without step-out.

Furthermore, the integrated damper is designed to apply a frictional load to the rotor in the thrust direction, so it can be installed in the dead space of the motor without increasing motor inertia, and the number of parts is small, allowing for compact assembly. be.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway front view of a stepping motor showing an embodiment of the present invention, Figure 2 is a plan view of the same motor with the frame removed, and Figure 3 is a section taken along line 1-1 in Figure 11. Some sectional views, Figure 24 is a partial sectional view of the line ■-■ in Figure 3, Figure 5 is a front view of the rotor, Figure 216 is a perspective view of the damping body as above, Figure 7 is as above. Dynamic characteristic diagram of a stepping motor, Figure 8 is a dynamic characteristic diagram of a conventional stepping motor. (1) Core, (5) Coil, (6) Rotor, @ Damping body. Procedural amendment (Mutsu) January 10, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi 1° Case 0 display 1988 Patent application 20483
No. 1, No. 2, Name of the invention Stepping motor 3, Relationship to the case of the person making the amendment Patent applicant 3, left Tokyo Electric Co., Ltd. 4, Agent Address: 4-3-22 Shinjuku, Shinjuku-ku, Tokyo 160 (Ando Building) Drawings subject to amendment by Party B

Claims (1)

[Claims] (1) A stepping motor comprising a stator core, a plurality of coils disposed inside the core, and a rotor disposed in an inner space of the core surrounded by the coils. A stepping motor characterized in that a damping body is disposed in an inner space of a core to apply a friction load to the rotor in a thrust direction to reduce a part of output torque.