JPH0727823Y2 - 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, an encoder is built in to improve the performance of the stepping motor, and a signal from the encoder is transmitted. There is an increasing demand for feedback 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 several improved stepping motors using a cup-cup type magnet rotor with low inertia and good response will be described below with reference to FIGS. 1 to 5.

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

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 to form 2P (P is a plurality of integer) poles,
For example, a cylindrical magnet rotor 5 having a driving magnetic pole 4 formed by magnetizing a multi-pole magnet such as 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, in order to prevent the air gap from increasing, the magnetic sensor 8 for position detection is provided in the stator armature (armature coil).
If embedded, the position adjustment of the magnetic sensor 8 becomes difficult, and mass productivity is not excellent.

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 shown in FIG. 1, but in this motor 1 ', the magnet rotor 5'is formed axially long to a position where it does not face the stator armature 6 and the extended magnet is used. A magnetic sensor 8 for position detection is arranged below the stator armature 6 facing the peripheral surface of the rotor 5'to detect 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 is 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 that described above, but has a cup-shaped magnet rotor 5 ″ as shown in FIG.

This magnet rotor 5 ″ has a driving magnetic pole 4 similar to the above on its peripheral surface, and a multi-pole magnetized magnetic encoder magnetic pole 9 is magnetically formed on the upper end surface thereof in the axial direction. The position detecting magnetic sensor 8 is disposed so as to face each other.

Although the stepping motor 1 ″ having this structure has an advantage that the drawbacks of the above-described conventional motors 1 and 1 ′ can be solved, the driving magnetic pole 4 and the magnetic encoder magnetic pole 9 have different magnetization directions, and Must be done separately,
There is a drawback that the number of manufacturing processes increases and the cost becomes high.

Further, since the magnetic encoder magnetic pole 9 is formed on the end surface,
That is, since it is an axial gap (axial) direction detection type, unless the mechanical accuracy in the thrust direction of the magnet rotor is made extremely accurate, the gap length between the sensor 8 and the magnetic encoder magnetic pole 9 fluctuates, and the position detection signal is detected. Is unstable, and a delicate magnetic encoder cannot be constructed.

[Problem of the Invention] The present invention provides a magnetic encoder suitable for closed loop control with high inertia, low inertia, good response, good efficiency, and high precision without using a large and expensive encoder. The problem was to make it possible to configure a servo stepping motor with a position detecting element similar to that built in it, at a small size and at low cost.

[Means for Achieving the Object of the Invention] An object of the present invention is to provide a stator armature in two upper and lower stages, and a cup-type or cylindrical magnet that faces the stator armature formed in the two upper and lower stages, respectively. A magnetic pole for driving is formed by radially orientating N and S magnetic poles in a 2P (P is a plurality of integers) pole at a fine pitch on the circumferential surface of the rotor, and the position between the stator armature of the upper stage and the stator armature of the lower stage is formed. A magnetic sensor for position detection is disposed at a stator armature position facing the magnet rotor of, and a concave portion is formed on the circumferential surface of the magnet rotor facing the magnetic sensor for position detection and between the upper and lower drive magnetic poles. Formed and N, S in the recess
To provide a servo stepping motor having a position detecting element, in which magnetic poles of the magnetic encoder are formed by magnetically magnetizing the magnetic poles of 2P poles in a radial direction alternately at fine intervals and facing the magnetic sensor for position detection in the recess. Achieved by

[Embodiment of the Invention] FIG. 6 is a longitudinal sectional view of the present invention as one embodiment, and FIG. 7 is a partially cutaway exploded perspective view of a PM type servo stepping motor of the present invention.

An embodiment will be described below with reference to FIGS. 6 and 7.

This servo stepping motor 10 has a drive magnetic pole 11-1 formed in a multi-pole magnetism at a fine pitch at a position on the outer peripheral surface facing the upper stage stator armature 14, and an outer peripheral surface facing the lower stage stator armature 15. The driving magnetic poles 11-2 are magnetized and formed in a plane position in multiple poles at a fine pitch.
An outer peripheral surface position facing the space is defined as a concave portion 13, and a cup-shaped magnet rotor 16 in which a magnetic encoder magnetic pole 12 is magnetized and formed at an inner surface position facing the concave portion 13 is integrally rotated with the rotary shaft 2.

The magnetic encoder magnetic poles 12 have the same magnetic N, S magnetic poles in the circumferential direction at the same pitch as the driving magnetic poles 11-1, 11-2 and at the same phase position as the driving magnetic poles 11-1, 11-2. Drive magnetic pole 11
It has the same number of poles as -1, 11-2, that is, it is multi-pole magnetized in the 2P pole radial orientation magnetization.

Originally, in the stepping motor 10, between the stator armatures 14 and 15 and the driving magnetic pole 11 of the magnet rotor 16.
Between -1 and 11-2 is a useless portion that does not contribute to the generation of torque of the motor, so that forming the recess 13 in this portion has no effect.

The recess 13 is provided with the position detecting magnetic sensors 8-1, 8 described later.
It is useful for storing -2. Also, this recess 13
It is the first to store the magnetic sensor magnetic poles 8-1, 8-2 in the first
Unlike the stepping motor 1 shown in the figure, since the air gap between the stator armature and the magnet rotor is not increased, even if a magnetic sensor is inserted in the air gap, the torque does not decrease. There are advantages.

A stator armature 14 is provided at a fixed position on the outer periphery of the magnet rotor 16 facing the drive magnetic pole 11-1 and a fixed position on the outer periphery of the magnet rotor 16 facing the drive magnetic pole 11-2. , The stator armature 15 is disposed, and the stator 17 surface between the two stator armatures 14 and 15 facing the recess 13 of the cup-shaped magnet rotor 16 facing the magnetic encoder magnetic pole 12 is electrically connected to each other. Two position detecting magnetic sensors 8-1, 8-2 are arranged with their phases shifted by 90 degrees at each angle.

More specifically, this stepping motor 10
Is a stator armature 1 with two magnetic hollow rings
There is a hollow stator 17 having a structure in which 4, 15 are vertically stacked.

The stator armatures 14 and 15 include a stator pole piece 18a, 19a, and a stator pole piece 18a, which will be described later.
A comb tooth type is formed to form 20a and 21a, and two pairs of the yokes 18 and 19 and 20 and 21 formed in a U-shaped cross section by bending the comb tooth type and a part of the outer periphery at a right angle. 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, in which the teeth are combined so as to mesh with each other.

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 magnetic pole pieces 18a and 19a and 20a and 21 are arranged and fixed so as to be superposed in two stages in the axial direction with an electrical angle difference of 90 degrees.

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 the stator coils of the stator armatures 14 and 15, respectively.
It is a lead wire connected to 23.

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 uses the through holes 30 and 31 with screws 32 to mount the motor mounting plate 2.
8, It is fixed to the printed circuit board 29.

The magnetic sensors 8-1 and 8-2 are electrically connected to the group of electric components 33 through a flexible printed circuit board having a printed power distribution pattern (not shown) and a printed power distribution pattern (not shown) formed on the printed circuit board 29. It is connected.

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 is configured such that the magnetic pole pieces 18a, 19a, 20a and 21a of the stator armatures 14 and 15 are provided.
Rotate relative to. The drive magnetic poles 11-1 and 11-2 are magnetized in a radial orientation.

As described above, in the PM type stepping motor 10 of the present invention, the driving magnetic poles 11-1 and 11-2 are formed on the outer periphery of the magnet rotor 16 at the portions facing the stator armatures 14 and 15, and the stator armatures 14 and 15 are formed. A recess 13 is formed in a wasteful portion of the magnet rotor 16 that faces the space between them, and the magnetic sensors 8-1 and 8-2 for position detection are disposed in the recess 13, and the recess 13 is formed in the recess 13 of the magnet rotor 16. Since the formed multi-pole magnetized magnetic encoder magnetic pole 12 is detected, only the position detecting magnetic sensors 8-1, 8-2 can be rationally arranged between the stator armatures 14, 15 and the magnet rotor 16. In addition, no special space is required for the position detecting magnetic sensors 8-1 and 8-2.

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 8-1 and 8-2 are arranged so as to be offset by 90 degrees in terms of electrical angle. In this case, it goes without saying that if one magnetic sensor capable of obtaining A-phase and B-phase encoder signals is used, it is not necessary to use two magnetic sensors.

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

Output signals from the magnetic sensors 8-1, 8-2 are taken out from the output lead wire 34 through an electric circuit formed by a printed power distribution pattern (not shown) formed on the printed circuit board 29 and a group of electric parts 33.

Therefore, the stepping motor 10 is controlled by the energization control circuit.
Is driven, the magnet rotor 16 rotates, and the magnetic encoder magnetic pole 12 formed on the gnet rotor 16 is detected by the magnetic sensors 8-1, 8-2, and the signal is extracted from the lead wire 34. Stepper motor
The rotation speed, rotation angle, rotation direction, etc. of 10 are known.

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.

[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. Moreover, in this case, when high-speed rotation is required, positioning control is extremely easy even if it is controlled as a normal DC brushless motor, and when using a stepping motor, the signal from the position detection element is fed back to perform closed-loop control. Therefore, there is an advantage that even if it is rotated at a high speed, the step does not occur.

(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 built-in can be configured, but since the magnet rotor that is a component of the magnetic encoder is a magnet rotor for driving the stepping motor, the stepping motor with a built-in magnetic encoder can be made compact and compact. It can be obtained at low cost.

(4) The position detecting element is arranged at a reasonable position, and even if the position detecting element is arranged at such a position, the air gap can be widened or lengthened as in the conventional servo stepping motor. Since the length is not lengthened, it is possible to obtain a servo stepping motor including a small position detection element having excellent efficiency and volume efficiency.

[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 5 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 a vertical sectional view of a servo stepping motor of the present invention. FIG. 7 is a partially cutaway exploded perspective view of the servo stepping motor. 1,1 ′, 1 ′ ′ …… Stepping motor, 2 …… Rotary axis,
3 ... Cup type rotor member, 4 ... Driving magnetic pole, 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 motor with position detection element, 11-1, 11-2 ...... Drive magnetic pole, 12 ...... Magnetic encoder magnetic pole, 13 ...... Concave, 1
4,15 …… stator armature, 16 …… magnet rotor, 17
...... Stator, 18, ……, 21 …… Yoke, 18a, 19a, 20a, 21a
...... Pole piece, 22 ...... Coil bobbin, 23 ...... Stator coil, 24,25 ...... Lead wire, 26 ...... Hollow part, 27 ...... Bearing, 2
8 …… Motor mounting plate, 29 …… Printed circuit board, 30,31 ……
Through hole, 32 ... Screw, 33 ... Electrical component, 34 ... Output lead wire.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shumi Miyao 4-9-4 Chuorinkan, Yamato-shi, Kanagawa Shico Giken Co., Ltd. Inspector Yasuyoshi Oikawa (56) Reference JP-A-58-175965 (JP) , A)

Claims (2)

[Scope of utility model registration request] 1. A stator armature is provided in two upper and lower stages,
The magnetic poles of N and S are 2P (P is a plurality of integers) at a fine pitch on the circumferential surface of a cup-type or cylindrical-type magnet rotor that faces the stator armatures formed in two steps above and below.
A magnetic pole for radial orientation is formed on the pole, and a magnetic sensor for position detection is arranged at a stator armature position facing the magnet rotor at a position between the upper stator armature and the lower stator armature. A concave portion is formed on the peripheral surface of the magnet rotor facing the position detecting magnetic sensor and between the upper and lower driving magnetic poles, and the magnetic poles of N and S are alternately aligned in the concave portion to the 2P pole at a fine interval. A servo stepping motor provided with a position detecting element, wherein a magnetized magnetic encoder magnetic pole part is formed, and a magnetic sensor for position detection is exposed in the recess. 2. The utility model registration claim, wherein the magnetic encoder magnetic pole portion formed on the magnet rotor is formed by magnetizing N and S magnetic poles at the same magnetic pitch as the driving magnetic pole and at the same phase position. A servo stepping motor including the position detection element according to item (1).