JPS5883576A - Stepping motor - Google Patents

Abstract

PURPOSE:To improve the responsiveness of a stepping motor by shortening the axial length by axially overlapping parts of the projections of adjacent pole plates and equalizing the circular-arc length of a rotor to that of the part overlapped with the projections. CONSTITUTION:A plurality, for example, 4 of pole plates 21-24 are fixed to a hollow stator shaft 1, and four projections 21a-24a whcih are radially projected to the plates 21-24 are formed at every 90 deg.. In this case, the opening angle between the projections 21a and 24a is set to 60 deg., and the opening angle between the projections 22a and 23a is set to 90 deg., and the adjacent projections 21a-24a are disposed axially to be overlapped partly, and the overlapped part is sequentially moved in the rotating direction. A rotor 6 is formed in a ring shape, a window is formed at the rotor 6, thereby forming the pole teeth 6a of the circular-arc length (opening angle of 30 deg.) corresponding to the length of the overlapped part of the projections 21a-24a are formed at the interval of 90 deg.. Three coils 3, 4, 5 disposed between the pole plates 21-24 are sequentially energized, thereby stepwisely driving the rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a unipolar stepping motor that configures a magnetic circuit within a plane that includes an axis of a rotating shaft.

Conventionally, in a unipolar stepping motor, a pair of fixed teeth and a coil wound between the teeth are provided as a set, and three buttons are provided in tandem in the direction of the rotation axis, and the rotor is provided with three buttons arranged in tandem in the direction of the rotation axis. Set the phase of each of the teeth corresponding to the three pairs of teeth of the child to 1.
It is known to move the rotor by 1/3 of the pitch of the teeth by sequentially exciting the coils of the front r stator.

In the above-mentioned conventional stepping motor, three pairs of southern parts must be formed on the rotor and the stator, and the shape and structure are complex. Therefore, in order to arrange the three pairs of teeth in tandem, the length in the direction of the rotation axis is long.
In addition, since the tooth portions are arranged opposite each other, there is a drawback that the outer diameter becomes large.

In view of the above-mentioned drawbacks, the present invention provides a stator with a plurality of magnetic pole plates arranged such that some of the protrusions of adjacent magnetic pole plates overlap each other in the direction of the rotation axis, and a stator arranged between the magnetic pole plates. It is an object of the present invention to provide a stepping motor whose shape and structure are simplified by forming pole teeth with a circular arc length corresponding to the circular arc length of the coil and the portion where the power is distributed before the rotor.

Hereinafter, one embodiment using the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the basic structure of a stepping motor according to the present invention, FIG. 2 is a partially cutaway side view, and FIG. 3 is an operation explanatory view. In these V planes, 1 is a hollow stator shaft, 2 is a plurality of magnetic pole plates fixed to the stator shaft 1, and each of the magnetic pole plates 21, 22, 23, 24 has a radially protruding portion. Four protrusions 21a, 22a
+ 23 a e 24 a are integrally formed every 90 c', the first magnetic pole plate 21 has a protrusion 21 a with an opening angle of 300, and the second magnetic pole plate 22 has a projection 21 a with an opening angle of 6. A protrusion f3a with an opening angle of 6f is formed on the third magnetic pole plate 23, and a protrusion f3a with an opening angle of 6f is formed on the third magnetic pole plate 23.
A protrusion 24a having an opening angle of 3° is formed on each of the protrusions 24a.

That is, the arc length of the projection 21a of the first magnetic pole plate 21 and the projection 24a of the fourth magnetic pole plate 24, and the arc length of the projection 22a of the second magnetic pole plate 22 and the projection 23a of the third magnetic pole plate 23. The ratio is 1:2.

The protrusions 21a of the first magnetic pole plate 21 overlap the left portions 22az of the protrusions 22a of the second magnetic pole plate 22 in the rotational axis direction, and the protrusions 223 of the second magnetic pole plate '22
The right portion 22a of the third magnetic pole plate 23 overlaps the left portion 23a of the projection 23a of the third magnetic pole plate 23 in the rotation axis direction, and the right portion 23a of the projection 23a of the third magnetic pole plate 23
, overlap the protrusion 24a of the fourth magnetic pole plate 24 in the direction of the rotation axis, and Zo3.4.5 correspond to the first to fourth magnetic pole plates 21.2, respectively.
The first to third coils disposed between the coils 2, 23, and 24 are sequentially excited by a control device (not shown). Reference numeral 6 denotes a ring-shaped rotor that is disposed close to the outer periphery of the magnetic pole plate 2 with a slight gap therebetween and is attached so as to be able to rotate relative to the stator shaft 1, and is connected to the first to fourth magnetic poles. Board 21
.
Two pole teeth 6a are formed at intervals of 9 degrees.

Next, the operation will be explained. A control device (not shown) that controls the energization of the coils 3, 4.5 determines the stop position of the rotor based on a signal from a rotational position detection device (not shown) attached to the rotor 6, as is well known. The coils 3 and 4 detect the
, 5, select the coil 3, 4.5 to start excitation of the coil 3, 4.5;
Alternatively, when the control circuit is stopped, excitation divided by -71 coils is memorized, and the next coil is energized at startup. This is to drive a stepping motor without causing a reverse rotation 1 or an error in the number of steps.

When the control device sequentially energizes the first coil 3 to the second coil 41 to the third coil 5, the rotor 6 in FIG. , when the first coil is excited, the first magnetic pole plate 21 and the second magnetic pole plate 22 are magnetized, and the magnetic circuit is connected to the second magnetic pole, such as the protrusion 21a of the first magnetic pole plate 21, respectively. A magnetic circuit is constructed by the left portion 22a1 of the protrusion 22a of the plate 22 and the pole teeth 6a of the rotor 6, and the rotor 6 is absorbed in the clockwise rotation direction as shown in FIG. Take one step forward.

When the second three E4 is excited, the right part 22a9 of the protrusion 22a of the magnetic pole plate 22 of l@2, the left m part 23a1 of the protrusion 23a of the third magnetic pole plate 23, and the pole of the rotor 6. tooth 6
a to form a magnetic circuit, and the pole teeth 6a are attracted to rotate the rotor 6 one more step in the clockwise rotation direction as shown in FIG. When the third coil is energized,
Similarly to the above, a magnetic circuit is constructed by the right portion 23a of the protrusions 2 and 3a of the third magnetic pole plate 23, the protrusion 24a of the fourth magnetic pole plate 24, and the pole teeth 6a of the rotor 6. , the pole teeth 6a are attracted and the rotor 6 is further rotated one step in the clockwise rotation direction as shown in FIG. 2(2). As mentioned above, the magnetic pole plate 21, 2223.2♀! Protrusion 21 a,
22a, 23a, and 24a each interact with the four pole teeth of the rotor 6 to rotate the rotor 6 one step at a time in the clockwise direction. The order in which the coils are energized is reversed, from the third coil 5 to the second coil 4. By energizing the first coil 3 in this order, reverse rotation can be easily achieved.

Note that the above-described stepping motor is not limited to the above-mentioned embodiment, and for example, contrary to the present embodiment, the magnetic pole plate 2 and the coils 3, 4 . ! The present invention can also be applied to a rotor in which i is fixed and a rotor having pole teeth facing the high cherry plate 2 is arranged inside. In addition, in order to reduce the step angle of the stepping motor according to the present invention, the pitch of the protrusions 21a, 22a, 23a, 24a of the stator and the corresponding pitch of the pole teeth 6a of the rotor 6 are reduced to reduce the step angle of the protrusion 21a. , 22a, 23a, 24a and the number of pole teeth 6a, it is possible to achieve the same performance as a high-precision stepping motor with a large number of steps.

In the stepping motor using the present invention, the thickness of the rotor in the radial direction can be reduced by opening a window in a part of the rotor 6 and using the remaining part as pole teeth, and the diameter of the stator can be reduced. Since the stator can be made larger by that amount, a cavity can be provided inside the stator. Therefore, the stepping motor according to the present invention has an optical system disposed inside the cavity as a driving source for an autofocus or autozoom mechanism in a lens of an optical device, and the stepping motor directly or decelerates the mechanism. When applied to something that can be driven via a mechanism, it can be integrated with the optical system, is small, and produces little noise, making it ideal as a drive source for the lens auxiliary mechanism described above.

As described above, the present invention uses a ring-shaped rotor with an opening in the rotor, and the large diameter portion has small inertia, so it has excellent responsiveness, and the large diameter portion is magnetic. Since it constitutes a circuit, it has the advantage that the ratio of current supplied can be adjusted by increasing the rotational torque, and the direction of rotation can be controlled arbitrarily. Furthermore, since the thickness of the magnetic pole plate can be reduced, there is an advantage that the length in the rotation axis direction can be shortened.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the main structure of an embodiment using the present invention, Fig. 2 is a partially cutaway front view, and Fig. 3 is an operation explanation V showing different operating states. be. DESCRIPTION OF SYMBOLS 1... Stator shaft, 21... First magnetic pole plate, 21a... Protrusion, 22... Second
magnetic pole plate, 22a...protrusion, 22a,...
...Left part, 22a*...Right part, 23
...Third protrusion, 23a...Protrusion, 2
3al...Left part, 23a...Right part, 24...Third magnetic pole, 24a...
...Protrusion, 3...First coil, 4...
...Second coil, 5...Third coil, 6.
...Rotor, 6a...Pole teeth.

Claims (1)

[Claims] A plurality of magnetic pole plates arranged on the same axis at intervals in the direction of the rotation axis are each integrally formed so as to protrude in the radial direction, and portions of the adjacent magnetic pole plates overlap in the direction of the rotation axis. , and protrusions formed so that the overlapping portions of the front portion sequentially move in the rotation direction;
A plurality of coils wound between the twists of the magnetic pole plate and a circumferential surface of each protrusion of the magnetic pole plate are provided with a slight air gap so as to be able to rotate relative to the magnetic pole plate. arranged,
A stepping motor comprising: a rotor having pole teeth having an arc length corresponding to the arc length of the mutually overlapping portions of the projections.