JPS61139260A - Actuator - Google Patents

Abstract

PURPOSE:To obtain smooth movement without torque ripple by detecting a pole teeth of a rotor to switch a current. CONSTITUTION:A coil is wound on a stator core 5, a permanent magnet 3 is mounted, and fixed through a yoke to a case 9. A position detector 12 is further disposed on the outer periphery of a rotor 4, and secured to a case 10. The detector 12 detects the irregular surface of teeth o fthe rotor 4 by magnetic or optical noncontact means. This is converted into an electric signal as a signal of an electron commutator for applying an energization command to the coil. Thus, the coil is enertized to obtain the maximum torque. The amplitude of the current is varied by an external command.

Description

[Detailed Description of the Invention] Industrial Application Fields Burnal computers are used as office equipment in many R fields,
As they have become popular in homes, floppy disk drives, hard disk drives, and optical disk drives are forming a major market as external storage devices. Among these devices, demand for hard disk devices with short access times and large capacity is gradually increasing.Hard disk devices are mainly driven by spindle motors.

disk, head actuator, magnetic head.

It consists of a disk enclosure, a breathing filter, a position control circuit, a two-rotation control circuit, and a recording/reproducing circuit.

Among these, the head actuator is an essential mechanism for positioning the magnetic head with high precision and high speed. The present invention relates to a head actuator for the above-mentioned hard disk.

2. Description of the Related Art Conventionally, head actuators for hard disks include a voice coil mortar type and a stepping motor type.

FIG. 9 shows an actuator constructed of a voice coil mortar type. An example of the voice coil motor type actuator mentioned above will be described below with reference to the drawings. In the figure, 2° is the yoke 22. Noyafuto 2
23 is a permanent magnet attached to the yoke 22, and 24 is a coil. , 121 is an arm which is directly connected to the coil and has a magnetic head attached to its tip.

Regarding the head actuator configured as above,
The operation will be explained below. A magnetic circuit composed of a yoke 22 and a permanent magnet 23 creates a static magnetic field in the gap. When a slidable coil 24 is placed in it and energized, a thrust is generated by Fleming's left hand side. The advantages of this method are that it is easy to manufacture and that it is easy to perform precise control because there is no cogging, but on the other hand, it has the disadvantage that it requires a large volume and consumes a lot of power in order to obtain the desired driving force.

Next, what about the actuator configured with a stepping motor type? The diagram is shown in Figure 10. An example of a stepping motor type actuator will be described below with reference to the drawings. 26 is a magnetic head, 27 is a shaft serving as a rotating shaft of arm 28, 29 is a pulley, and 3o is a stepping motor.

A metal band is wrapped around the pulley 29, and the metal band is fixed between the arm 28 and the pulley 29. The arm 28 moves as the stepping motor 3Q rotates. Since the stepping motor type can be driven in an open loop, the control circuit is simpler and the driving force per motor volume can be greater than that of the voice coil motor type. However, there is a limit to how fine the step angle can be made, and it is not suitable for precise position control.

Problems to be Solved by the Invention As mentioned above, voice coil motors have the disadvantages of large volume and high power consumption, and stepping motors have the problem of difficulty in minute position control, which makes it difficult to achieve high precision. Actuators with positioning performance and high torque performance have not yet been obtained.

In view of the above-mentioned problems, the present invention provides an actuator having fine position controllability and high torque performance.

Means for Solving the Problems In order to solve the above problems, the actuator of the present invention includes a rotor core made of a magnetic material having a plurality of concave and convex magnetic pole teeth arranged at a constant angular pitch on the outer periphery; A stator core made of a magnetic material and having a plurality of magnetic pole tooth groups facing the rotor with a slight air gap and having a plurality of magnetic pole teeth having the same angular pitch as the magnetic pole teeth; and a stator core that is attached to the stator core. a permanent magnet, a plurality of multiphase coils wound around the stator core, and a bearing device that maintains a constant air gap between the rotor core and the stator core to enable smooth rotation; A non-contact type position detector disposed on the outer periphery of the rotor that detects the magnetic pole teeth of the rotor, converts them into electrical signals, and outputs a plurality of substantially sinusoidal position signals having mutually different phases. It is.

Function The present invention generates torque based on reluctanos change similar to that of a stepping motor, and can generate large torque with relatively low power consumption.
Since the cogging force is small, it is suitable for minute positioning. Furthermore, by detecting the magnetic pole i of the rotor and switching the current, smooth movement without torque ripple can be obtained.

EMBODIMENT OF THE INVENTION Hereinafter, an actuator according to an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the principle diagram. This figure shows the motor of the present invention developed in a straight line.

The stator core 1 is roughly divided into magnetic pole tooth groups A and B.

It consists of a core 2a having magnetic pole teeth A, B, and a core 2b having magnetic pole tooth groups A, B, and Cf. The magnetic pole tooth groups A, B, and C are rotor magnetic pole teeth (
0 pitch, L/3 pitch, respectively for pitch L)
- L/3 pitch deviation, magnetic pole tooth groups A, B, C are each L/2 pitch, L/2 + L/3 pitch,
It is shifted by L/2-L/3 pitch. At this time, the change in vermeance of each magnetic pole tooth group can be treated as a sine wave by devising the tooth shape, and P A':: P□+ pcO5θ PH=P
o pCCiSθP B= P () + pCO5(θ
-1200) PH=Po-pcos(θ-120°
) PC=Po+pcO3(θ-2400) P6=P
□ pcos(θ-24oO)Po-(Prnax+P
m1n)/2p=(Pnax-Pmin)/2Ptna
Technique: Teeth facing n + Pm1n ”When both valves face, θ=2π
Also, the magnetic flux created by the permanent magnet is
yc=(1+pOCM(θ-2400))φMφM
A = (1pr-CQSfl)φMφM5=(1
-,c 1l-1200)jφM3φM=The coil current is selected as follows for the average magnetic flux method created by a permanent magnet.

I A=I (plnθ I, H= I□s+n
θI B= I 0sln (θ-1200) I H
= I □Sin (θ-12oo) I c: I □
sin (θ-2400) I E knee I □Sln
(θ-240°) As a result, the magnetic flux created by the coil is φCA” ”AIA φCλ=-NPiIλφ.

3=-NPBIBφ. s = -N P100Iiφc
c knee JJpcI c φccE= -NPcIC
Number of coil turns per N knee pole tooth group On the other hand, the reluctance change is Rp, = R()-r QCSθ ”A=R
□+ rcosθRB=R() rcOs(θ−12
0') RB=R□+rCO5(θ-12CP)Rc
=Ro-rcos(θ-240') to R==R□+
rCO5(θ-2400)RO"("rnax +Rw
in )/2'=(Rmaz "min)/2R1
1na engineering: When the teeth are not opposed + Rmi When the teeth are opposed, each phase thrust is Ri Fi = - + φi2 (i = A, B, C, A, B, C
) x The total thrust is found to be able to perform nozzle-free motion.

Theoretically, the absence of cogging and torque ripple improves positional accuracy. In other words, it is not necessary to increase the gain of the control loop, and as a result, the mechanical resonance point can be set low and assembly becomes easier. In addition, because of the smooth movement, unnecessary vibrations can be suppressed, resulting in shorter settling time and shorter access time. FIG. 2 is a sectional view, and FIG. 3 is a sectional view showing how the position detector is attached.

Rotor core 4 with teeth formed at the same angle on the outer periphery
is press-fitted into the shaft 11 and fixed to the cases 9 and 10 via the bearing device 7. On the other hand, a stator core 5 has a coil 6 wound thereon, a permanent magnet 3 attached thereto, and is fixed to a case 9 via a yoke. Furthermore, the position detector 12
is arranged around the outer periphery of the rotor 4 and fixed to the case 1o.

This position detector 12 detects the unevenness of the teeth of the rotor 4 by magnetic or optical non-contact means. This is converted into an electrical signal and used as a signal for an electronic commutator that gives energization commands to each coil. Therefore, the coil 6 is energized to obtain the maximum torque.

Furthermore, the amplitude of the current can be varied by an external command.

Figure 4 shows the shape of the rotor core 4, and Figure 5 shows the stator core 5.
shows the shape of The basic unit of the stator core 5 is six groups of magnetic pole teeth each having a different phase from the magnetic pole teeth of the rotor core 4. Of course, a plurality of basic units of magnetic pole tooth groups may be arranged within the same stator.

FIG. 6 shows the side where the permanent magnet 3 is attached to the stelta armor. Mounting in the stacking thickness direction via the yoke 13 as shown in a, mounting on the outer periphery of the stator core 5 as shown in b, mounting between the stator cores 5 as shown in C, and sandwiching between two cores as shown in d. There is a way to make it look like this. The position detector 12 is arranged between the stator cores as shown in FIG.

FIG. 8 shows a block diagram of the drive circuit.

It should be noted that from theory to practical examples, three-phase was assumed, but it goes without saying that two-phase may also be used.

Effects of the Invention As described above, the present invention comprises a rotor having uneven teeth at a constant angular pitch on its outer periphery, a stator consisting of a group of magnetic pole teeth having a different phase with respect to the rotor, and a stator arranged on the outer periphery of the rotor and having uneven teeth. The basic course is about position detectors that detect positions from. Based on the principle of reluctance of magnetic pole teeth,
The generated torque is large, and by selecting the phase of the magnetic pole tooth group and the energizing current, a motor with no torque ripple can be obtained.Furthermore, the total magnetic resistance is constant, so cogging is eliminated and position control is easy to perform. It produces effects such as becoming.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of the present invention, Fig. 2 is a cross-sectional view of an actual winding example of the present invention, Fig. 3 is a cross-sectional view showing the installation of the same position detector, and Fig. C is a front view showing the rotor shape. 6 is a front view showing the stator shape, FIG. 6 is a perspective view showing an example of attaching a permanent magnet to the stator, FIG. 7 is an explanatory diagram showing the relationship between the stator core and the position detector, and FIG. 9 is a block diagram of the drive circuit, FIG. 9 is an explanatory diagram of a conventional voice coil type actuator, and FIG. 1Q is an explanatory diagram of a conventional stepping motor type actuator. 3...Permanent magnet, 4...Rotor core,
5... Stator core, 6... Coil,
7...Bearing, 12...Position detector. Name of agent: Patent attorney Toshio Nakao and 1 other person (Chestnut 4)
Figure 5 Flash Figure 6 (b) Figure 16 (CJ 3 Figure 7 Figure 8

Claims (1)

[Claims] A rotor core made of a magnetic material having a plurality of uneven magnetic pole teeth at a constant angular pitch on the outer periphery, and a plurality of magnetic poles facing the rotor with a slight air gap and having the same angular pitch as the magnetic pole teeth. A stator core made of a magnetic material having a plurality of magnetic pole teeth groups, a magnet attached to the rotor core, and a plurality of multiphase coils wound around the stator core. , a bearing device that rotatably supports the rotor core, and a bearing device arranged on the inner periphery of the stator that detects the magnetic pole teeth of the rotor and converts it into an electrical signal at a plurality of positions of substantially sinusoidal waves having mutually different phases. An actuator equipped with a non-contact position detector that outputs a signal.