JPS6331462A - Stepping motor - Google Patents

Abstract

PURPOSE:To enhance the response of a stepping motor by providing a spiral groove in the surface of a rotor shaft, magnetizing the crest between the groove, and converting the rotary motion of the rotor into a linear motion of the motor output shaft to reduce its inertia. CONSTITUTION:In a stepping motor which can convert the rotary motion of its rotor 1 into the linear motion of its output shaft 5, the shaft 5 of the rotor 1 is rotatably and slidably supported to bearings, and has a pair of bearing brackets for supporting the stator 2. The magnetic head of a load is attached to the end of the shaft 5. In this case, nonmagnetized spiral grooves 11 are formed in the surface of the outer periphery of the rotor 1, and the spiral crest 12 is magnetized along its length such that it holds alternately opposite poles. Further, windings 21 and 22 and teeth 23 are formed on the salient poles 13-17 on the inner periphery of the stator 2, and energized. Thus, the exciting phases of the windings 21 and 22 are switched to rotate the rotor 1 in necessary steps to move forward or revere the shaft 5 in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor capable of converting rotational motion of a rotor into linear motion of an output shaft.

[Conventional technology]

Conventionally available stepping motors include stepping motors in which the rotor rotates by a fixed angle each time an input pulse is applied, and linear motors in which the stator is formed into a long strip and the mover moves along it. The only known type of motor is a stepping motor.

[Problem that the invention seeks to solve]

However, in the former normal stepping motor,
The output shaft cannot move in the axial direction and can only obtain rotational motion. Furthermore, the latter linear stepping motor directly obtains linear motion, and does not obtain it by converting rotational motion into linear motion. Moreover,
In this linear stepping motor, the mover that moves along the stator is formed using soft magnetic steel having permanent magnets and salient poles, so the mover is large and heavy.

Therefore, the overall size is large, the cost is high, and the inertia of the mover is large, so the response is not good, and the damping characteristics are also not good due to large vibrations.

[Means for solving problems]

The present invention provides a spiral groove that is essentially a non-magnetized portion on the outer periphery of the rotor material, and a spiral convex portion between the grooves left on the outer periphery of the rotor material along the spiral groove in the winding direction. A rotor is used in which S poles and N poles are alternately magnetized along the rotor, and a plurality of salient poles around which windings are wound are provided protruding from the inner surface of a stator housing this rotor, and the tips of these salient poles are A large number of teeth are formed at equal intervals along the axial direction of the stator, and the pitch of the teeth along the axial direction of the stator is set to the adjacent S poles along the winding direction of the inter-groove spiral convex portion. The pitch between the and N poles is an integer multiple of the pitch along the rotor axis direction, and the output shaft that supports the rotor is slidably passed through the bearing that rotatably supports the output shaft. In addition to solving the above problems, the rotor can be easily magnetized.

[Effect]

This stepping motor is operated by sequentially switching the excitation of the phases consisting of the salient poles and windings of the stator, and the rotor is magnetically attracted so that the magnetic poles of the rotor face each other at the t-th excited point. is rotated by a certain step angle. At the same time as this rotation, each time the rotor rotates by one step angle, the above-mentioned magnetic attraction action causes the rotor to attract adjacent comrades of different polarity that are alternately magnetized along the winding direction in the spiral protrusion between the grooves. The total movement is the same as the pitch along the rotor axis. In this way, since the rotor is moved in the axial direction as the rotor rotates, the output shaft, which supports the rotor and slidably passes through the bearing, moves linearly. Furthermore, the inertia beams of the rotor and output shaft are smaller and lighter than the movable element of the stepping motor, and by providing the rotor with a spiral groove, the weight can be further reduced. Furthermore, when making a rotor, spiral grooves are provided in the rotor material, so the same polarity is lined up along the outer periphery of the rotor material over the entire axial length, and different poles are arranged alternately in the circumferential direction. By performing this, different poles are necessarily magnetized alternately along the winding direction of the inter-groove spiral convex portion.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the figure, 1 is a rotor, and 2 is a stator that accommodates the rotor 1.

As shown in FIG. 2, the stator 2 is supported by a stator support, for example, a pair of bearing brackets 3 fitted to both ends of the stator 2 in this embodiment. Bearings 4 are mounted inside the center portions of these brackets 3, respectively.

These bearings 4 rotatably support an output shaft 5 located on the central axis of the stator 2. The output shaft 5 slidably passes through the bearing 4, and a load is connected to one of the protruding shaft ends 5a.

Note that the stepping motor of this embodiment illustrated in FIG. 2 is used as a power source for a seek operation of a magnetic storage device. In this regard, the recessed groove 5b provided in the shaft end 5a
A load, that is, a head support 8 having a magnetic head 7 at its tip is attached via a bearing 6 to the head support 8 . A part of the head support 8 is attached to the bearing bracket 3 on the shaft end 5a side.
The magnetic head 7 is slidably fitted into a guide 9 fixed to the magnetic head 7, so that the magnetic head 7 is reciprocated in the radial direction along the medium (magnetic disk).

The rotor 1 is supported by an output shaft 5. The rotor 1 is provided with a spiral groove 11 that is essentially a non-magnetized portion on the outer periphery of the rotor material, and an inter-groove spiral convex portion 12 left on the outer periphery of the rotor material is formed along the spiral groove 11. , magnets are used in which S and N poles are alternately magnetized along the winding direction. In addition, the first
The dotted line in the first part of the rotor in the figure indicates the boundary between different polarities.

Therefore, on the outer periphery of the rotor 1, magnetic poles of equal polarity are arranged at predetermined intervals along the axial direction, and magnetic poles of different polarity are arranged alternately in the circumferential direction. In addition, in this embodiment, in order to further increase the torque and thrust force of the rotor 1, a case is shown in which a plurality of spiral grooves 11 and inter-groove spiral protrusions 12 are provided, but each of these is provided with a single thread. It's okay.

Further, the outer periphery of the rotor material is magnetized by one of the following two methods. One magnetization method is to first carve a spiral groove 11 on the outer periphery of the rotor material and at the same time form a spiral protrusion 12 between the grooves, and then attach a magnetizing yoke longer than the entire axial length of the rotor material to the outer periphery of the rotor material. The inter-groove spiral convex portion 12 is mainly magnetized by being arranged along the axial direction. Another method of magnetization is to first arrange a magnetizing yoke that is longer than the entire axial length of the rotor material along the outer circumference of the rotor material in the axial direction, and then magnetize it.
Spiral grooves 11 are carved on the outer periphery of this magnetized rotor material, and inter-groove spiral convex portions 12 are formed at the same time. Note that in the above magnetization, the spiral groove 11 is also magnetized, but since this groove 11 is further away from the inter-groove spiral convex portion 12 than the teeth 23 of the salient poles 13 to 20, which will be described later, it is actually not magnetized. It can be treated as a department.

In this embodiment, the S poles and N poles that are alternately magnetized in the inter-groove spiral convex portions 12 are holes, respectively, and in the subsequent explanation and drawings, they will be easily identified. , with subscripts 1 to 6 added to each column. Further, ΔX in FIG. 1 indicates the pitch along the axial direction of the rotor 1 between the adjacent south pole and north pole along the winding direction of the inter-groove spiral convex portion 12.

The stator 2 has a substantially cylindrical shape and is longer than the rotor 1, and has a plurality of, for example, eight salient poles 13 on its inner surface.
20 are integrally protruded along the radial direction centered on the axis of the stator 2.

Windings 21 and 22 are alternately wound around these salient poles 13 to 20.

Note that since this embodiment shows a stepping motor of a two-phase bipolar drive system, one winding 21 has one salient pole.
3.15.17.19, and the winding directions around the salient poles 13.17 and 15.19 are opposite to each other. Similarly, the other winding 22 is wound over the salient poles 14.16.18.20 and over the salient poles 14.18 and 16.
The windings around 20 are in opposite directions.

A large number of teeth 23 are integrally formed at the tip of each of the salient poles 13 to 20 at equal intervals along the axial direction of the stator 2, respectively. The distance between two adjacent teeth 23 along the axial direction of the stator 2, that is, the pitch of the teeth 23, is determined to be an integral multiple of the pitch ΔX between the S pole and the N pole. 1. Since the step angle is set to 15°, for example, depending on the number of poles of the rotor 1 and the number of salient poles, the step angle is set to 3ΔX.

The stepping motor having the above configuration is operated by switching the excitation phase as shown in the following table.

In other words, when the winding 21 is energized in step 1,
The salient poles 13, 15, 17, and 19 are each excited, but due to the difference in the winding direction of the winding 21, the salient poles 13.17 and 15.19 are excited with different polarities, respectively. In this case, the salient pole 13.17 is the N pole, and the salient pole 15.19 is the S pole.
Since each pole is excited, the magnetic poles Sl, N2, S4, and N5 of the rotor 1 will be stabilized in a position where they are particularly opposed to the teeth 23 of each exciting phase 1, 15, 17, and 19 due to magnetic attraction. shall be. This situation is shown in FIG.

Next, when the current in the winding 21 is cut off and the current is applied to the winding 22 to proceed to step 2, the salient poles 14, 16, 18.
The salient poles 14.18 and 16.20 are respectively excited with different polarities due to the different winding directions of the windings 22. In this case, t'! ii! 14
．． 18 is excited to the S pole, and the salient poles 16.20 are excited to the N pole, so each excited phase 14.20 is excited by the magnetic attraction action.
16. Magnetic pole N1 of rotor 1 against tooth 23 of 18.20
, S3, N4, and S8 are particularly opposed to each other, and the rotor 1 rotates clockwise by 15 degrees and attempts to stabilize at the position shown in FIG.

Furthermore, in step 3, the current in the winding 22 is cut off, and a current in the opposite direction to that in step 1 is passed through the winding 21 to switch the excitation phase, so that the rotor 1 is rotated clockwise due to the magnetic attraction action. Then, it is rotated an additional 15 degrees. Subsequently, in step 4, the current in the winding 21 is cut off, and a current in the opposite direction to that in step 2 is passed through the winding 22 to switch the excitation phase, so that the rotor 1 is
is rotated an additional 15° clockwise.

By switching the excitation phase in accordance with the input pulse in this manner, the rotor 1 can be rotated clockwise by the necessary steps, and by switching the excitation phase in the order 1, which is the reverse of the above explanation. , the rotor 1 can be rotated counterclockwise by the required steps.

Since each of the magnetic poles of the rotor 1 is arranged in a spiral shape, the poles magnetically attract each other and face the teeth 23 of the salient poles to stabilize themselves, and at the same time,
It is moved in the axial direction by ΔX for one step. Therefore, the rotor 1 and the output shaft 5 can be stepped forward or backward along the axial direction depending on the number of steps.

This allows the magnetic head 7 shown in FIG. 2 to perform a seek operation with respect to the medium 10, for example.

According to the stepping motor that can convert the rotational motion of the rotor 1 into reciprocating linear motion of the output shaft 5 as described above, it is constructed by combining mechanical elements such as a crank mechanism, an eccentric wheel, gears, a rack/binion, and a cam. Compared to a mechanical conversion mechanism, the frictional part is extremely small, so it can be converted with high efficiency, and the movement stroke of the output shaft 5 can be changed arbitrarily, which was almost impossible with such a mechanical conversion mechanism.
Furthermore, even minute strokes can be easily and accurately obtained.

Along with this, the total weight of the rotor 1 and the output shaft 5 can be made smaller than the mover of the conventional linear stepping motor, and a spiral groove 11 is provided on the outer periphery of the rotor 1, and a spiral convex portion 12 between the grooves. Since the rotor is constructed by alternately magnetizing the S pole and the N pole, it can be made lighter than the rotor of a normal stepping motor.

Since the inertia of the rotor 1 is reduced in this way, it is possible to improve responsiveness, reduce vibrations, and improve damping characteristics. Moreover, the stepping motor in which the rotor is rotated is generally smaller than the linear stepping motor, and the motor of the present invention does not lose this feature, but it also has the same drive as a conventional stepping motor that rotates only. It can be driven depending on the method.

Furthermore, since the spiral grooves 11 are provided in the rotor material when manufacturing the rotor 1, magnetic poles of the same polarity are lined up along the outer periphery of the rotor material over the entire axial length, and different poles are arranged alternately in the circumferential direction. By magnetizing using the magnetizing yoke, it is naturally possible to magnetize the inter-groove spiral convex portion 12 with different poles alternately along the winding direction thereof. Therefore, when magnetizing the rotor 1, there is no need to specially develop and magnetize a magnetizing yoke corresponding to each magnetic pole, each of which is quite small. can be used as is to easily perform predetermined magnetization. In addition, a spiral groove is provided in the unmagnetized rotor material, and the pre-formed magnet pieces are inserted and glued one by one into this groove, and these magnet pieces are inserted from the surface of the spiral convex part between the grooves. Even if the rotor is made to protrude, it is possible to make the rotor move in the axial direction as the rotor rotates, but in this case, it takes a lot of effort and is troublesome, but there is no method that does not use this method. According to the invention, the rotor material can be easily magnetized for the reasons described above.

Although the above-mentioned embodiment is constructed as described above, it goes without saying that the spiral convex portion between the grooves is provided with at least one turn in the present invention, and the present invention can be implemented in various applications including various actuators. The rotor drive method may be a unipolar method instead of a bipolar method, and the number, pitch, etc. of salient poles and rotor poles can be arbitrarily determined according to design specifications.

In addition, when implementing the present invention, unless it is contrary to the gist of the invention, specific structures, shapes, positions, etc. of the rotor, spiral grooves, inter-groove spiral protrusions, stators, salient poles, teeth, output shafts, bearings, etc. Of course, the materials and the like can be configured and implemented in various ways without being restricted to the one embodiment described above.

〔Effect of the invention〕

According to the present invention, the gist of which is the configuration described in the claims above, it is possible to convert the rotary motion of the rotor into linear motion of the output shaft, which was impossible with a conventional stepping motor having a rotor, and Compared to linear motion using a near stepping motor, it has the effect of having small inertia, high responsiveness, low vibration, and good damping characteristics.Moreover, it is easy to magnetize the rotor. By providing a spiral groove in the rotor material, the rotor can be made even lighter and the inertia described above can be reduced.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view of the main part with a part cut away, Fig. 2 is a schematic longitudinal sectional side view of the whole shown with a load, and Figs. 3 and 4 are different from each other. It is a schematic sectional view of a state. 1... Rotor, 2... Stator, 4... Bearing, 5
...Output shaft, 11...Spiral groove, 12...Spiral convex portion between grooves, 13-20...Salient pole, 21.22
...Winding, 23...teeth.

Claims (1)

[Claims] A spiral groove is provided on the outer periphery of the rotor material, which is essentially a non-magnetized portion, and along this spiral groove, an S pole is formed in the inter-groove spiral convex portion left on the outer periphery of the rotor material along the winding direction. A rotor is used, in which a rotor is alternately magnetized with north and north poles, and a plurality of salient poles around which windings are wound protrude from the inner surface of a stator housing this rotor, and each of the salient poles has a A large number of teeth are formed at equal intervals along the axial direction of the stator, and the pitch of the teeth along the axial direction of the stator is set between adjacent S and N poles along the winding direction of the inter-groove spiral convex portion. A stepping motor characterized in that the output shaft is slidably passed through a bearing that rotatably supports the output shaft that supports the rotor and has a pitch that is an integral multiple of the pitch along the rotor axis direction.