JPS62193549A - Pm-type stepping motor with built-in magnetic encoder - Google Patents

Abstract

PURPOSE:To realize miniaturization and low cost by forming magnetic encoder pole sections in the open end face portion of a magnet rotor having drive poles formed by multipolar magnetization radially of a motor. CONSTITUTION:A magnet rotor 4 for driving subjected to multipole magnetization in radial directions is rotatably provided in a hollow portion formed at the central part of a magnetic body hollow ringlike stator armature having pole pieces on the inner peripheral portion and a conductor wound on the inner part. Magnetic encoder pole sections 12 magnetized axially and having many N and S poles alternately and at narrow spaces are formed in the open end face portion of the magnet rotor 4. Magnetic sensors 19 are arranged oppositely to these magnetic encoder pole sections 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a PM type stepping motor that has a built-in magnetic encoder so as to be suitable for closed loop control and is suitable for servo control.

[Prior art and its problems] Stepping motors, not just PM types, have the advantage of being easy to position, open-loop control, and requiring a simple circuit configuration, so they can be constructed at low cost.

However, a stepping motor has the drawback that when it rotates at high speed, it cannot keep up with the signal from the circuit and loses synchronization.

For this reason, they are not suitable for high-speed rotation, and are inferior to DC brushless motors at high-speed rotation.However, in recent years, in an effort to improve the performance of stepping motors, they have built-in encoders and fed back signals from the encoder to enable high-speed rotation. However, there has been a growing demand to prevent loss of synchronization.

Providing a 1-inch encoder on the stepping motor has the disadvantage that the stepping motor becomes large and expensive.

[Aspects of the Invention] The present invention was made with the object of obtaining a compact and inexpensive RPM type stepping motor with a built-in magnetic encoder suitable for closed loop control, without using a large and expensive encoder. It is something.

[Means for Achieving the Object of the Invention] The object of the present invention is to axially magnetize the open end face of a magnet rotor having drive magnetic poles formed by multi-pole magnetizing in the radial direction of a PM stepping motor. This is achieved by forming a magnetic encoder magnetic pole part and arranging a magnetic sensor opposite to this magnetic pole part.

[Embodiment of the Invention Fig. 1 is an exploded bottom perspective view showing an embodiment of the invention;
The figure is a bottom perspective view of a PM type stepping motor. FIG. 3 is a longitudinal sectional view of the magnet rotor. The invention will be described in detail below with reference to this figure.

l is a PM type stepping motor with a built-in magnetic encoder.
Ia indicates a single stepping motor unit of the stepping motor 1. This stepping motor unit part 1a has 2
Stator armature 2a, 2 having two magnetic hollow rings
There is a hollow stator 2 having a structure in which the stator b is stacked in two layers, upper and lower.

The stator armatures 2a and 2b have magnetic surfaces, and magnetic pole pieces 3a and 3b, 3a' and 3b' are arranged with minute gaps in order to form N and S magnetic poles alternately on the inner periphery. A large number of them are formed alternately, and a number of turns of conductive wire are wound inside them. The magnetic pole pieces 3a and 3b, 3a' and 3b' are arranged and fixed in two stages, upper and lower, so as to face each other in the axial direction. Magnetic pole pieces 3a and 3b+ 3a' and 3b'
The width is approximately equal to the width of one magnetic pole of the driving magnetic pole 5 of the magnet rotor 4, which will be described later. Pole pieces 3a and 3a
' are formed by extending the magnetic bodies on the lower surfaces of the stator armatures 2a and 2b upward to the inner periphery, and are also formed to be shifted by a half pitch from each other. Also, the magnetic pole pieces 3b and 3b
' are formed by extending the magnetic material on the upper surface of the stator armatures 2a, 2b toward the inner circumference downward direction, and are also formed to be shifted by a half pitch from each other. 7 are lead wires connected to the conductive wires of the stator armatures 2a and 2b, respectively. The cylindrical magnet rotor 4 is configured to rotate integrally by fixing the inner periphery of the upper end of the magnet rotor 4 to the outer periphery of a disc-shaped boss 9 fixed to the rotating shaft 8. The magnet rotor 4 is rotatably supported in a hollow part 11 formed in the center of the stator 2 by a bearing (not shown) provided in the inner hollow part 10 (see FIG. 3). The magnet rotor 4 may be a plastic magnet or a sintered magnet as appropriate. Further, the magnet rotor 4 may be cup-shaped. In this case, when forming a mold using a plastic magnet, the boss 9 can be omitted by integrating one end of the rotating shaft 8 in the center and fixing the rotating shaft 8. It is very convenient because it can be manufactured at low cost. On the outer periphery of the magnet rotor 4, as shown in FIG. 2, the above-mentioned magnetic pole pieces 3a and 3b are provided.

81 poles of N and S having a width equal to the width of 3a' and 3b' form a driving magnetic pole 5 which is alternately magnetized into multiple poles, and the magnetic pole pieces 3a, 3b, 3a', and 3b' have 10 poles. It is rotated counter-clockwise. At the lower end of the magnet rotor 4, as shown in Fig. 1, N and S magnetic poles are alternately magnetized in the axial direction at fine intervals (fine intervals than the drive magnetic poles 5). A magnetic encoder magnetic pole part 12 is formed. A fixing plate 13 for motor mounting is fixed to the upper end surface of the stepping motor 1. A through hole 14 for attachment is formed in the fixed plate 13. A position regulating hole 15 is formed in the lower surface of the stator armature 2b. Reference numeral 16 denotes a disk-shaped printed circuit board, and on the bottom surface of this board 16, electrical components 17 constituting an electric circuit for a magnetic encoder are arranged, and are electrically connected to a printed power distribution pattern (not shown) by soldering. . In this case, in order to make the PM type stepping motor 1 with a built-in magnetic encoder thin, the electric circuit must include an amplifier circuit for amplifying the signal from the magnetic sensor, and a waveform shaping circuit for shaping the signal. It is desirable to limit the amount to a circuit and an amplifier circuit (such as an operational amplifier) that amplifies the output signal from the circuit. However, the energization control circuit for the stepping motor 1 may be built-in. In particular, if the energization control circuit is made into an IC, it can be made smaller, and in this case, it can be easily built in. A post insertion hole 18 is formed in the printed circuit board 16 at a location that substantially coincides with the regulation hole 15 described above. Further, a magnetic sensor housing hole 20 for storing and fixing the magnetic sensor 19 is formed in a portion of the printed circuit board 16 facing the magnetic encoder magnetic pole part 12 so that the detecting part 19a can be exposed. This storage hole 20
The magnetic sensor 19 is housed and fixed, and the detection section 19a is opposed to the magnetic encoder magnetic pole section 12. In this embodiment, a magnetoresistive element (referred to as an MR sensor) is used as the magnetic sensor 19. As the magnetic sensor, a Hall element, a Hall IC, or a magnetic head, which is often used as a position detection element of brushless motors as a magnetoelectric conversion element, may be used. However, in order to configure a magnetic encoder, it is necessary to obtain A-phase and B-phase signals, but these magnetic sensor elements do not convert the two elements into electrical angles in order to obtain A-phase and B-phase signals. This has the drawback of increasing assembly and adjustment time. Furthermore, if up to the Z phase is required, a total of three magnetic sensor elements will be required, and the above-mentioned drawbacks will further increase. Furthermore, in order to obtain a more accurate motor l and magnetic encoder, the magnetic encoder magnetic pole part 12 may have a plurality of N and S magnetic pole pitches magnetized to a fine width (for example, 100 μm pitch). It is very difficult to align and arrange the magnetic sensor elements with human spacing.
This is difficult and unsuitable for mass production. I'm fji again!・is large and expensive, so its use should be avoided if possible. Therefore, this embodiment depicts a case where a magnetoresistive element is used as the magnetic sensor 19, which can obtain A-phase, B-phase, and even Z-phase signals even though it is a single element. Since it is just one magnetic sensor element, positioning on the printed circuit board 16 is only required, and the PM type stepping motor 1 with a built-in magnetic encoder can be mass-produced at low cost and easily.

This magnetoresistive element utilizes the effect that the electrical resistance of the element changes when a magnetic field is applied, and is a low-pulse type.
-3b semiconductor magnetoresistive element, but the magnetic sensor 19 of this embodiment is made of a Ni-Fe system or a Ni-Co system and has a high sensitivity in a low magnetic field. A magnetic magnetoresistive element is used. Magnetic sensor 1
The terminal portions 19b of 9 are electrically connected to conductive contacts 21 formed on the printed circuit board 16 by soldering. A magnetic encoder is mainly composed of the encoder magnetic pole part 12 and the magnetic sensor 19. The output signal from the magnetic sensor 19 is transmitted to the terminal portion 19b, the contact 21, and the printed circuit board 16.
Printed power distribution pattern (not shown) formed on and! It is taken out from the output lead wire 22 through an electric circuit formed by the air component 17. Reference numeral 23 designates a cup-shaped magnetic encoder storage case, which has an engagement hole 25 formed at the bottom of its inner surface to engage with the lower end of a post 24 (to be described later), and a peripheral surface 23a for passing the Riet wire 22 through. A notch 26 is formed. Moreover, in this peripheral surface part 23a,
A plurality of small holes (not shown) are formed, and the case 23 can be fixed to the lower surface of the stator armature 2b by screwing using the small holes. Post 24
has a step 24a formed in the center, and the upper end 24a
b and the lower end portion 24c are formed into a thin body portion.

The support 24 has its upper end 24b passed through the regulation hole 15 and the support insertion hole 18, and the lower end of the step 24a inserted into the printed circuit board 1.
6 is engaged. The lower end portion 24c of the support column 24 is inserted into and engaged with the engagement hole 25, and the lower portion of the stepped portion 24a is fitted to the inner surface of the case 23.

Therefore, the energization control circuit controls the stepping motor l.
When driven, the magnetic encoder magnetic pole part 12 is detected by the magnetic sensor 19, and the signal is sent to the lead wire 22.
If you take it out, you can find out the rotational speed, rotational angle, rotational direction, etc. of the motor l. By feeding back the rotation information of the motor 1 to the energization control circuit and applying closed loop control, it is possible to obtain a stepping motor that will not step out even if it is rotated at high speed.

[Effect of the invention] According to the present invention, there are mainly the following effects.

(]) It is possible to obtain an iEiPM stepping motor in a magnetic encoder suitable for use as a servo, which can be freely adjusted from low speed to high speed and has easy positioning, and can be mass-produced at low cost and easily. (2) It does not require the installation of an expensive and large commercially available encoder, and it does not have the disadvantages of optical encoders, such as being susceptible to dirt and dust, causing electrical noise, causing malfunctions, and having a short lifespan, and is equipped with a magnetic encoder. In addition, it is possible to obtain a small, inexpensive, and high-performance product.

(3) A magnetic encoder that uses the magnetic rotor of a stepping motor to support the rotor of the magnetic encoder without providing any special member to rotatably support it, so it has fewer parts and can be manufactured at low cost. Built-in P
An M-type stepping motor can be obtained. (4) According to the PM type stepping motor with a built-in magnetic encoder of the present invention, the magnetic encoder can be built-in and the size can be reduced in the thrust direction.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the present invention, FIG. 2 is an exploded perspective view of a PM stepping motor, and FIG. 3 is a longitudinal sectional view of a magnet rotor. 1... iPM type stepping motor in magnetic encoder, 2... stator, 2a, 2b... stator armature,
3a, 3b, 3a', 3b'...Magnetic pole piece, 4.
... Magnet rotor, 5... Drive magnetic pole, 6,7.
... Riet wire, 8... Rotating shaft, 9... Boss, 10.
...Inner hollow part, 11...Hollow part, 12...Magnetic encoder magnetic pole part, 13...Fixing plate for motor mounting, 1
4... Installation through hole, 15... Position regulation hole, 1G.
...Printed circuit board, 17...Electrical parts, 1st...Strut insertion hole, 19...Magnetic sensor, 19a...Detection section, 19b...Terminal section, 20...1i71 air sensor storage Hole, 21... Conductive contact, 22... Output lead wire, 23... Cup-shaped magnetic encoder case, 23a.
... Peripheral part, 24... Support column, 24a... Step part, 24
b...upper end, 24c...lower end, 25...engaging hole. Figure 2 Box 3 Procedure Correction Port C'jf Burning 5 May 1986 6 1. Indication of the Case Japanese Patent Application No. 61-35754 2. Name of the Invention PM Type Stepping Motor with Built-in Magnetic Encoder 3 - Correction Relationship with the case of a person who does Is the full text of detailed contents 6 as attached? [Yes (no change in content).

Claims (1)

[Claims] A multi-pole magnetized magnet rotor for driving is rotated in the radial direction in a hollow part formed in the center of a magnetic hollow ring-shaped stator armature that has magnetic pole pieces on its inner periphery and a conductive wire wound inside. In a PM-type stepping motor that is movable, a magnetic encoder magnetic pole portion is formed by magnetizing the open end surface of the magnet rotor in the axial direction and having a large number of N and S magnetic poles alternately spaced at small intervals. A PM type stepping motor with a built-in magnetic encoder that has a magnetic sensor arranged opposite the magnetic pole part.