JP2516670Y2 - Servostepping motor with position sensing element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a position detection element suitable for closed-loop control, and consequently has a built-in magnetic encoder, and is suitable for servo control. The present invention relates to a servo stepping motor equipped with a position detecting element having low inertia and excellent responsiveness, which is capable of rationally obtaining

[Prior Art and its Problems] The stepping motor has a feature that it can perform positioning without an encoder, and has a merit that it can be inexpensively constructed because a simple open loop control circuit configuration is sufficient. However, when the stepping motor is rotated at a high speed, it cannot keep up with the signal from the circuit, and there is a drawback that it loses synchronization.

Therefore, the stepping motor is not suitable for high-speed rotation and is inferior to the DC brushless motor at high-speed rotation, but in recent years, in order to improve the performance of the stepping motor, an encoder is built in and the signal from the encoder is fed back. Therefore, there is a strong demand to prevent step-out even when rotating at high speed.

By using an encoder, it is possible to realize a servo stepping motor that is capable of high-speed rotation, free speed conversion from low-speed to high-speed rotation, and easy positioning.

Attaching an encoder to the conventional stepping motor here has a drawback that the stepping motor becomes large and expensive.

To that end, several improvements have been made and some examples of these are given.

Conventional examples of some improved stepping motors using a cup-shaped magnet rotor with low inertia and good response will be described below with reference to FIGS. 1 to 7.

First, in the conventional stepping motor 1 shown in FIG. 1, a cup type rotor member 3 made of a non-magnetic material such as plastic or aluminum is fixed to a rotating shaft 2.

On the peripheral surface of the cup-shaped rotor member 3, as shown in FIG. 2, N and S magnetic poles are alternately arranged on the peripheral surface by 2P (P is a plurality of integers).
A cylindrical magnet rotor 5 having a driving magnetic pole 4 formed by magnetizing a pole, for example, a multipole magnet having 100 poles in a radial orientation is fixed.

A stator armature 6 such as a drive coil is provided on the fixed side of the magnet rotor 5 that faces the drive magnetic pole 4 so as to make relative rotation.

In the space 7 between the stator armature 6 and the magnet rotor 5, a position detecting magnetic sensor 8 such as a Hall element, Hall IC, magnetic resistance element or the like for detecting a rotational position is used to detect the driving magnetic pole 4. It is installed in.

In this stepping motor 1, since the magnetic poles for driving and the magnetic sensor 8 for position detection constitute a magnetic encoder, a stepping motor with a built-in magnetic encoder can be made compact and inexpensive without specially attaching an encoder such as a magnetic encoder. Can be configured.

However, according to such a configuration, since the position detecting magnetic sensor 8 is disposed in the void portion 7, the air gap length is increased by the thickness of the sensor 8, so that a strong magnetic flux cannot be obtained, which is large. There is a drawback that the torque cannot be obtained and the efficiency is lowered.

In this case, if the position detecting magnetic sensor 8 is embedded in the stator armature (armature coil) in order to prevent the air gap from increasing, it becomes difficult to adjust the position of the magnetic sensor 8 and the mass productivity becomes poor. have.

The stepping motor 1'shown in FIG. 3 has been made to solve the above-mentioned drawbacks.

The structure is almost the same as that of the stepping motor 1 of FIG. 1, but in this motor 1 ', up to a position where the magnet rotor 5'does not face the stator armature 6,
This magnet rotor 5'is formed to be long in the axial direction and extends.
A magnetic sensor 8 for position detection is arranged below the stator armature 6 facing the circumferential surface of the magnetic pole 4 for detecting the magnetic pole 4 for driving.

With this configuration, the drawbacks of the stepping motor 1 shown in FIG. 1 can be solved, but this time, since the magnet rotor 5'becomes longer than necessary in the axial direction, the motor efficiency (volume efficiency) with respect to the motor volume becomes poor. There is a drawback.

The stepping motor 1 ″ shown in FIG. 4 was made in order to eliminate the drawbacks of the stepping motors 1, 1 ′ shown in FIGS. 1 and 3.

This stepping motor 1 ″ has the same structure as the above, but has a cup-shaped magnet rotor 5 ″ as shown in FIG. 5 integrally fixed to the rotary shaft 2 by a plastic magnet.

This magnet rotor 5 ″ has a driving magnetic pole 4 similar to the above on the peripheral surface, and a multi-pole magnetized magnetic encoder magnetic pole 9 is axially magnetized and formed on the upper end surface of the magnet rotor 5 ″, facing the magnetic encoder magnetic pole 9. Then, the position detecting magnetic sensor 8 is provided.

The stepping motor 1 ″ having this structure has an advantage that the drawbacks of the above-described conventional motors 1 and 1 ′ can be eliminated, but since the driving magnetic pole 4 and the magnetic encoder magnetic pole 9 have different magnetization directions, Because it has to be done separately,
It has the drawback of increasing the number of manufacturing processes and increasing the cost.

Further, since the magnetic encoder magnetic pole 9 is formed on the end surface, that is, it is of the axial gap (axial) direction detection type, the mechanical accuracy in the thrust direction of the magnet rotor must be made extremely accurate, and the sensor 8 and the magnetic The gap length between the encoder magnetic poles 9 fluctuates, the position detection signal becomes unstable, and a delicate magnetic encoder cannot be configured.

In order to overcome the drawbacks of the stepping motor, the inventor of the present invention has previously proposed a magnet rotor 5 as shown in FIG.
Has developed a stepping motor 1 having a magnetic sensor 8 for position detection provided on the inner surface thereof.

This stepping motor 1 includes a magnet rotor 5
Are formed as follows.

Referring to FIG. 7, the magnet rotor 5 has the same driving magnetic pole 4 formed on the outer periphery thereof.

A magnetic encoder magnetic pole 9 is formed by generating a magnetic flux of the drive magnetic pole 4 (a magnetic flux of a magnetic pole having a polarity opposite to that of the drive magnetic pole 4) on the inner surface of the magnet rotor 5.

By detecting the magnetic encoder magnetic pole 9 by the magnetic flux generated on the inner surface of the magnet rotor 5 by the position detecting magnetic sensor 8, the servo stepping motor 1 having the built-in magnetic encoder is constructed.

According to the servo stepping motor 1, a useful one which can eliminate the drawbacks of the stepping motors 1, 1, ′, 1 ″ can be obtained. Here, the magnetic encoder magnetic pole 9 and the driving magnetic pole 4 have the same phase with each other. It is necessary to form the magnetic poles with the same pitch and the opposite pitch.

If this is not done, an accurate magnetic encoder signal cannot be obtained from the position detecting magnetic sensor 8 due to the magnetic encoder magnetic pole 9 being influenced by the driving magnetic pole 4 having a strong magnetic flux, so that the servo stepping motor with high accuracy can be obtained. This is because 1 cannot be obtained.

As a result, only the magnetic encoder magnetic poles 9 having the same magnetizing pitch as the driving magnetic poles 4 can be obtained, so that only a limited encoder signal can be obtained.

If the magnetizing pitch of the magnetic encoder magnetic poles 9 is made more finely in order to obtain the servo stepping motor 1 with higher accuracy, the drive magnetic poles 4 are affected in the same manner as described above. Will have.

[Problems of the Invention] The present invention does not use a large and expensive encoder, and has low inertia, good response, good efficiency, good volume efficiency, and more encoder signals can be obtained, that is, driving. The magnetic encoder magnetic poles can be ignored and the number of magnetic poles attached to the magnetic encoder can be made larger than the number of magnetic poles for driving, which is suitable for higher precision closed loop control. The challenge was to make a servo stepping motor equipped with various position detection elements compact and inexpensive.

[Means for Achieving the Object of the Invention] A stator armature 1 formed in an annular shape over two upper and lower stages.
A cup-type or cylindrical-type magnet rotor provided with 4 and 15 and rotatably supported inside the stator armature.
16 are provided on the circumferential surface of each magnet rotor facing between the upper stator armature and the lower stator armature.
Driving poles 11-1 and 11-2 are formed by magnetizing N and S magnetic poles in a fine pitch to a 2P (P is a plurality of integers) poles in a radial orientation, and the upper and lower stator armatures 14 and lower poles are magnetized. The two drive magnetic poles 11-1 and 11- formed so as to face the stator.
A magnetic encoder magnetic pole 12 is formed by alternately magnetizing N and S magnetic poles in a 2P pole at a fine interval in a non-magnetized portion 13 on the surface of the magnet rotor 16 facing between the two magnetic poles, and facing the magnetic encoder magnetic pole. This can be achieved by providing a servo stepping motor provided with a position detecting element in which the position detecting magnetic sensors 8-1 and 8-2 are arranged so as to be able to detect the magnetic pole.

[Embodiment of the Invention] FIG. 8 is a longitudinal sectional view of the present invention as an embodiment, and FIG. 9 is a partially cutaway exploded perspective view of a PM type servo stepping motor of the present invention.

 The embodiment will be described below with reference to FIG.

In this servo stepping motor 10, the drive magnetic poles 11-1 are magnetized and formed in multiple poles at a fine pitch at the outer peripheral surface position of the magnet rotor 16 facing the upper stage stator armature 14.
Further, the driving magnetic poles 11-2 are formed in multiple poles at a fine pitch at the outer peripheral surface position of the magnet rotor 16 facing the lower stage stator armature 15 so as to face between the stator armatures 14 and 15. The position of the outer peripheral surface of the magnet rotor 16 between the magnetized drive magnetic poles 11-1 and 11-2 is the non-magnetized portion 13,
A cup-shaped magnet rotor 16 having a magnetic encoder magnetic pole 12 in which N and S magnetic poles are alternately magnetized in a 2P pole at fine intervals at an inner surface position of the magnet rotor 16 facing the non-magnetized portion 13 is provided on a rotating shaft 2 It is designed to rotate together with it.

The magnetic encoder magnetic pole 12 has magnetic poles having the same pitch as that of the driving magnetic poles 11-1 and 11-2 and having a polarity opposite to that of the driving magnetic poles 11-1 and 11-2 and driving magnetic poles 11-1 and 11-2. It is magnetized from the inner surface to the in-phase position.

By doing so, the magnetic encoder magnetic pole 12 is prevented from being adversely affected by the magnetic flux of the drive magnetic poles 11-1 and 11-2.

A stator armature 14 is arranged at a position on the outer circumference fixed side facing the driving magnetic pole 11-1, and a stator armature 15 is arranged on a position on the outer circumference fixed side facing the driving magnetic pole 11-2. Cup type magnet rotor facing the magnetic encoder magnetic pole 12
Two position detecting magnetic sensors 8-1 and 8-2 are arranged on the inner peripheral portion of 16 so as to be 90 degrees out of phase with each other in electrical angle.

In more detail, this stepping motor
10 is a stator armature having two magnetic hollow rings
There is a hollow stator 17 having a structure in which 14, 15 are vertically stacked.

In the stator armatures 14 and 15, the inner peripheral portion of a doughnut-shaped thin plate made of a magnetic material has stator pole pieces 18a and 19b to be described later.
Two pairs of yokes 18 and 19 and 20 and 21 formed into a comb shape to form a, 20a, and 21a, and this comb shape and a part of the outer circumference are bent at a right angle to have a U-shaped cross section. The comb teeth are combined so that they mesh with each other, and a large number of turns of the stator coil 23 are wound around a coil bobbin 22 having a U-shaped cross section and a donut shape, which is made of an insulating material.

Therefore, the stator pole pieces 18a and 19a and 20a and 21a form N and S magnetic poles alternately by energizing the stator coil 23.

The pairs of pole pieces 18a and 19a and 20a and 21a have an electrical angle of 90
They are arranged so that they are offset from each other and stacked in two stages in the axial direction.

The width of the magnetic pole pieces 18a and 19a, 20a and 21a is substantially equal to the width of one magnetic pole for driving 11-1 and 11-2 of the magnet rotor 16 described later.

24 and 25 are lead wires connected to the stator coils 23 of the stator armatures 14 and 15, respectively.

The cup-shaped magnet rotor 16 is integrally formed with one end of the rotary shaft 2 at the center of the cup magnet rotor 16 when the mold is formed by the plastic magnet so as to rotate integrally with the rotary shaft 2.

The magnet rotor 16 is rotatably supported by a bearing 27 provided in the inner hollow portion 26.

 The bearing 27 is fixed to the motor mounting plate 28.

The printed circuit board 29 is located inside the magnet rotor 16 and is fixed to the motor mounting plate 28 with screws 32 using the through holes 30 and 31.

The through hole 30 is an elongated hole, and the magnetic sensor 8 fixed to a fixing member 33, which will be described later, fixed on the printed circuit board 29 by the through hole 30 and the screw 32 serves as a magnetic encoder magnetic pole 12.
It is arranged so that it can be adjusted to the optimum position facing the.

The magnet rotor 16 may be either a plastic magnet or a sintered magnet, and an appropriate magnet may be used.

The magnet rotor 16 has a merit in that it is formed in a cup shape by using a plastic magnet as described later, but the magnet rotor 16 may not necessarily be formed in a cup shape. In this case, a boss is fixed to the rotary shaft 2 and A magnet rotor formed of a cylindrical plastic magnet or the like may be fixed.

The magnetic pole widths of the driving magnetic poles 11-1 and 11-2 are the same as the magnetic pole pieces 18a, 19a, 20a and 21a.

The magnet rotor 16 having the driving magnetic poles 11-1 and 11-2 includes magnetic pole pieces 18a, 19a, 20a, 2 of the stator armatures 14, 15.
Rotate relative to 1a. The drive magnetic poles 11-1 and 11-2 are magnetized in a radial orientation.

Thus, in the PM type stepping motor 10 of the present invention,
A magnet rotor having drive magnetic poles 11-1 and 11-2 formed on the outer periphery of the magnet rotor 16 facing the stator armatures 14 and 15 and facing the magnetized portion 13 between the stator armatures 14 and 15. Since the multi-pole magnetized magnetic encoder magnetic pole 12 formed on the inner periphery of 16 is formed in the radial orientation magnetized, the magnetic encoder magnetic pole 12 is strongly magnetized on the surface of the magnet rotor. The magnetic sensor 8 is also strongly magnetized so that it is not greatly affected by
Since it is not greatly affected by 4, 15, the magnetic encoder signal can be accurately obtained from the magnetic sensor 8.

In this embodiment, Hall elements are used as the magnetic sensors 8-1 and 8-2. Therefore, in order to obtain the A-phase and B-phase signals, the two magnetic sensors 8 are arranged at an electrical angle offset of 90 degrees.

As the magnetic sensor 8, a magnetic resistance element (MR element), a Hall IC, or a magnetic head may be used instead.

The output signal from the magnetic sensor 8 is a printed power distribution pattern and electric parts 34 (not shown) formed on the printed circuit board 29.
Lead wire for output through electric circuit composed of groups
Taken out from 35.

Therefore, the stepping motor is controlled by the energization control circuit.
When 10 is driven, the magnet rotor 16 rotates,
The magnetic encoder magnetic pole 12 formed on the magnet rotor 16 is detected by the magnetic sensor 8, and if the signal is taken out from the lead wire 35, the rotation speed, rotation angle, rotation direction, etc. of the stepping motor 10 can be determined.

By feeding back to the energization control circuit according to the rotation information of the stepping motor 10 and performing closed loop control, it is possible to obtain a stepping motor or one that does not lose step even when rotated at high speed.

FIG. 10 shows another magnet rotor 16 'of the present invention, in which the magnetic encoder magnetic poles 12' are multi-pole magnetized at the same position as the magnet rotor 16 described above. The magnetic pole 12 'is the driving magnetic pole 11-1.11-2
The number of magnetic poles is larger than the number of magnetic poles.

Even in this case, the driving magnetic poles 11-1, 11-2 are similar to the above.
However, it will be almost negligible.

[Effects of the Invention] According to the present invention, the following effects are mainly obtained.

(1) It is possible to mass-produce inexpensively and easily a servo stepping motor equipped with a position detection element suitable for a servo, which can be freely operated from low speed to high speed and whose positioning is extremely easy. In addition, the signal from the position detection element is fed back to perform the closed loop control, so that there is an advantage that the step out does not occur even when the high speed rotation is performed.

(2) Conventionally, there are drawbacks such as the fact that an expensive and large-sized encoder that is commercially available on the market is not attached, and that it is vulnerable to dust and dirt like an optical encoder, malfunctions due to electrical noise, and a short life. Instead, a magnetic encoder built-in type servo servo stepping motor having a small size, low cost, and good performance can be obtained because a magnetic encoder provided as a result can be configured simply by providing the position detecting element.

(3) As a result, a magnetic encoder having a built-in magnetic encoder can be configured. However, the magnet rotor that is a component of the magnetic encoder is a magnet rotor for driving the stepping motor, and the magnetic encoder is attached to the driving magnet rotor. Even if the magnetic encoder magnetic poles are formed to form the magnetic encoder magnetic poles, there is almost no influence of the driving magnetic poles, and a magnetic servo encoder built-in type servo stepping motor having high accuracy can be obtained at low cost.

(4) Since the air gap is not widened or lengthened unlike the conventional servo stepping motor, it is possible to obtain a servo stepping motor having a small position detecting element excellent in efficiency and volume efficiency. .

(5) A magnetic encoder magnetic pole is formed on the inner surface of the magnet rotor, and this is detected by a magnetic sensor, so there is no trouble in assembly such as increasing the mechanical accuracy in the thrust direction, and mass production assembly is easy. it can.

(6) When disposing the magnetic sensor, it is possible to easily dispose the magnetic sensor at a reasonable position without forming a special space therefor.

[Brief description of drawings]

FIG. 1 is an explanatory view of a conventional stepping motor, FIG. 2 is a perspective view of a magnet rotor of the stepping motor, and FIG.
4 and FIG. 4 are explanatory views of another conventional stepping motor, FIG. 5 is a perspective view of a magnet rotor used in the stepping motor of FIG. 4, and FIG. 6 is an explanatory view of another conventional stepping motor. 7 is a perspective view of a magnet rotor used in the stepping motor, FIG. 8 is a longitudinal sectional view of the servo stepping motor of the present invention, FIG. 9 is a partially cutaway exploded perspective view of the servo stepping motor, and FIG. FIG. 4 is an explanatory view of another magnet rotor of the present invention. 1,1 ′, 1 ″, 1 …… Stepping motor, 2 …… Rotary shaft, 3 …… Cup type rotor member, 4 …… Drive magnetic pole, 5,
5 ', 5 ", 5 ... Magnet rotor, 6 ... Stator armature, 7 ... Air gap, 8,8-1,8-2 ... Magnetic sensor for position detection, 9 ... Magnetic encoder magnetic pole, 10 ...... Servo stepping motors equipped with position detection elements, 11-1, 11-2 ...
… Drive magnetic pole, 12 …… Magnetic encoder magnetic pole, 13 …… Non-magnetized part, 14,15 …… Stator armature, 16 …… Magnet rotor, 17 …… Stator, 18, ・ ・ ・, 21 …… York, 18a, 19
a, 20a, 21a …… Pole piece, 22 …… Coil bobbin, 23 …… Stator coil, 24,25 …… Lead wire, 26 …… Hollow part, 27
...... Bearing, 28 …… Motor mounting plate, 29 …… Printed circuit board, 30,31 …… Through hole, 32 …… Screw, 33 …… Fixing member, 34
...... Electrical parts, 35 …… Output lead wire.

Claims (4)

(57) [Scope of utility model registration request] 1. A cup-type or cylindrical-type magnet rotor (16), which is provided with stator armatures (14, 15) formed in an annular shape in two stages above and below and is rotatably supported inside the stator armature. ) Is provided, and the magnetic poles of N and S are radially aligned and magnetized to 2P (P is a plurality of integers) poles at a fine pitch on the circumferential surface of each magnet rotor facing between the upper stator armature and the lower stator armature. Drive magnetic pole (11-
1, 11-2) are magnetized to form the upper stator armature.
14 and the above-mentioned two driving magnetic poles (11-1, 11-2) formed so as to face the lower-stage stator, and the non-magnetized portion (13) of the magnet rotor (16) surface facing each other alternately have a fine interval. To form a magnetic encoder magnetic pole (12) that is radially oriented and magnetized on the 2P pole, and oppose the position detecting magnetic sensors (8-1, 8-2) so as to face the magnetic encoder magnetic pole and detect the magnetic pole. Servo stepping motor equipped with a position detection element. 2. A magnetic encoder magnetic pole formed on the magnet rotor, wherein a magnetic pole having a magnetizing pitch equal to that of the driving magnetic pole and a polarity opposite to the driving magnetic pole is provided from a surface opposite to the magnet rotor facing the stator armature. A servo stepping motor provided with a position detecting element according to claim (1), which is formed by magnetizing. 3. The utility model registration claim (1) or claim (3) wherein the drive magnetic pole is not formed by magnetizing the drive magnetic pole between the upper stage stator armature and the lower stage stator armature. 2) A servo stepping motor equipped with the position detection element described above. 4. The utility model registration claim (1) or (3) according to claim 1, wherein the magnetic encoder magnetic poles are magnetized in a finer number of poles than the number of magnetic poles for driving. Servo stepping motor with position detection element.