JPH0556621A - Electromagnetic rotating machine - Google Patents

Abstract

PURPOSE:To eliminate a necessity of an excitation timing detector such as a conventional Hall element and realize a reduced thickness of the title machine by providing generating filaments for detecting an excitation timing. CONSTITUTION:An electromagnetic rotating machine has a rotor and a stator, and comprises magnetic field generating means 102 having a circumferential shape and provided on the stator. Further, it comprises magnetic field generating means 102 for generating a rotating magnetic field by energizing a plurality of phases of exciting currents, multipolarly magnetized drive magnet 101 provided on the rotor side to obtain a rotary magnet from the magnetic field, and coil means for detecting a magnetic field change generated when the magnet 101 provided on the rotor is rotated and having generating filaments (104, 105, 106) etched to be formed on the stator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic rotating machine such as a motor used in, for example, a floppy disk drive device, and more particularly to improvement of timing detection for generating a rotating magnetic field.

[0002]

2. Description of the Related Art Conventionally, in order to generate a rotating magnetic field for rotating a motor, a motor rotation phase detecting device detects a magnetic change of a magnet at a position facing a magnetic pole surface of a drive magnet of a rotating body. A method is known in which a hall element or the like is provided and a timing signal for generating a rotating magnetic field is synthesized based on a signal from the hall element.

A conventional motor configuration will be described with reference to the drawings. FIG. 1 is a cutaway plan view of a main part of a conventional three-phase brushless motor, and FIG. 2 is a sectional view taken along the line XX of FIG. In such a conventional brushless motor, four magnetic circuits are provided, namely, a magnetic circuit for generating a rotational driving force, a magnetic circuit for generating an FG signal, a magnetic circuit for generating a rotational position signal, and a rotating magnetic field. A magnetic circuit for detecting the excitation timing for generating is formed.

First, a schematic structure of a three-phase brushless motor will be described with reference to FIG. The substrate 7 is made of a magnetic material such as iron, and the oil-impregnated bearing 9 is press-fitted into the central portion thereof, while the Hall element 14 serving as a rotational position detecting means is provided at the outer peripheral end portion.
Are installed. The rotary shaft 5 is integrally provided with the rotor yoke 4 via the shaft fixing member 6, and is further fitted to the inner race of the bearing 8 provided above the oil-impregnated bearing 9 and the oil-impregnated bearing 9. The rotor yoke 4, the drive magnet 1, the FG magnet 2, the position detecting magnet 13, and the like integrally rotate with respect to the substrate 7.

A drive magnet 1 (FIG. 1) is fixed to the outer edge portion of the rotor yoke 4, and as is well known, a rotating magnetic field is applied to the drive magnet 1 to rotate the rotor yoke 4. Therefore, as shown in FIG. 1, the drive magnet 1 is multi-polarized with 16 poles in the radial direction, and is fixed inside the outer edge portion of the rotor yoke 4.

To actuate a rotating magnetic field, a plurality of drive coils 10 are provided wound around a stator yoke 11, while the stator yoke 11 is used to rotate the rotating shaft 5.
A plurality of drive coils are radially formed around and the plurality of drive coils are provided on the yoke 11 in the circumferential direction. The stator yoke 11 is fixed on the iron substrate 7 by a fixing member such as a screw (not shown).

In the above structure, the stator yoke 11
Together with the drive magnet 1, the rotor yoke 4, and the drive magnet yoke 3 form a closed magnetic circuit. still,
A brushless motor of the type in which the drive magnet 1 is provided in the radial direction of the stator yoke 11 so as to be separated from the yoke 11 is referred to as a circumferentially opposed motor.

A cutout 4 is formed on the outer peripheral surface of the rotor yoke 4.
h is processed and molded, and the position detecting magnet 13 as the rotational phase detecting means is embedded in the cutout portion 4h. This magnet 13 also constitutes one magnetic circuit.

Further, a plurality of Hall elements 12a, 12b, 1 for detecting the excitation timing of the coil 10 of each phase.
2c is fixed to an appropriate position on the substrate 7. The magnetic field from the drive magnet 1 is applied to these Hall elements 12a, 1
2b, 12c, so these elements 12a, 12
b and 12c detect changes in the magnetic field from the magnet 1 to detect the phase difference of the magnetic field to be generated by the coil 10 of the stator 11 with respect to the magnetic field of the rotating drive magnet 1. An electric current is passed through and a rotating magnetic field is generated. This rotating magnetic field causes the rotor 4 to rotate in the direction of arrow A in FIG.

On the other hand, the FG magnet 2 is fixed to the outermost peripheral edge portion of the rotor yoke 4, and is magnetized for 120 poles in total. On the surface portion of the iron substrate 7 facing the FG magnet 2, 120 power generating line elements 7a having a pattern as shown in FIG. 3 are formed by etching with a copper pattern or the like.

With the above configuration, when the rotor yoke 4 is started to rotate, a sine wave having a frequency corresponding to the rotation speed of the rotor yoke 4 is generated from the power generating line element 7a. Therefore, a constant speed rotation control is performed by a control circuit (not shown). Is done.

When the rotor yoke 4 rotates, the magnet 13 fixed to the rotor yoke 4 also rotates integrally. Therefore, the change in the magnetic field of the magnet 13 is sensed by the index position detecting Hall element 14, and the rotor yoke 4 rotates once. On the other hand, one pulsed so-called position detection signal is generated. The pulse signal allows detection of the rotation phase of the rotating body.

When the rotor yoke is started to rotate,
Hall elements 12a, 1 for detecting the drive timing of each phase
2b and 12c output waveforms as shown in FIG. Based on this signal, the coil drive signal synthesis circuit 15 shown in FIG.
By this, the timings at which currents are passed through the drive coils 17a, b, c are combined, amplified by the coil drive amplifiers 16a, b, c, and the currents shown in FIG. 5 flow through the coils.
The motor rotates.

[0014]

However, according to the above-mentioned conventional timing position detecting method, a space for providing a detecting element having a certain size such as a Hall element for timing detection is required, which is a multi-phase. This prevents the brushless motor from becoming smaller and thinner. Further, there is a problem that the product cost becomes high.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to reduce the number of constituent components to realize a compact / thin-profiled multiphase brushless motor. is there. Furthermore, it is to realize cost reduction.

[0016]

The structure of the electromagnetic rotary machine of the present invention for achieving the above-mentioned object is an electromagnetic rotary machine comprising a roller and a stator, wherein the circumferential shape provided on the stator is The magnetic field generating means has a magnetic field generating means for generating a rotating magnetic field by supplying exciting currents of a plurality of phases, and a multi-pole attachment provided on the rotor side to obtain a rotating torque from the rotating magnetic field. A magnetic drive magnet and a coil means for detecting a magnetic field change generated when the drive magnet provided on the rotor rotates, in which the power generating line element is formed by etching on the stator. It is characterized in that it is provided with the coil means.

That is, since the power generating line element is provided for detecting the excitation timing, it is possible to make the device thinner, and at the same time, the conventional excitation timing detection element such as a Hall element is not required, and the cost can be reduced. ..

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a face-to-face brushless motor will be described below with reference to the accompanying drawings.

FIG. 6 is a sectional view of a face-to-face type motor of the embodiment. 7 is a plan view for explaining the magnetized state of the rotor-side magnet, and FIG. 8 is a view for explaining a line element pattern for detecting a signal for generating phase timing on the stator side. 6 and 7, the same elements as those in the conventional example of FIG. 1 are designated by the same reference numerals.

In FIGS. 6 and 7, the drive magnet 101 covers the back surface of the rotor as shown in FIG. 7, and is divided into eight poles and magnetized. In the pattern 101a, each pole has a fan shape. A magnet 201 for generating an FG signal is provided further on the outer circumference of the drive magnet 101.

FIG. 8 shows patterns (104, 105, 10) of line elements formed on the drive coil 102 on the stator side.
6) and the line element 7a for FG signal detection. The line element pattern 7a for the FG signal is provided in a position facing the FG magnet 201 on the substrate 7 in a rectangular repeating pattern shape. Since the FG magnet is magnetized to 120 poles, the line element 7
a is also composed of 120 line elements. Therefore, the line element 7a generates 60 pulses per rotation.

Since the motor of the embodiment is a three-pole motor, a coil 102 for generating a magnetic field that gives a driving force to the driving magnet 101 is also required for three phases. This three-phase coil
As shown in FIG. 6, it is formed on the substrate 7. In order for the three-phase rotating magnetic field to drive the rotor, the drive timing must be detected in three phases. In order to detect this timing, U-, V-, and W-phase power generation line elements 104, 105, and 106 having a pattern as shown in FIG. 8 are formed on (or inside) the drive coil 102. 1
Each of the line elements 04, 105 and 106 has eight poles, which is the same as the number of poles of the drive magnet. Since one pole of each line element is repeated in the same cycle as the pattern 101a of the drive magnet 101, one pole of each of the power generation line elements 104, 105 and 106 changes by 4 cycles during one rotation of the rotor. Generates a sine wave. Power line elements 104, 105,
Each of the four poles of 106 produces a sine wave, so
A superposition of these four sine waves (each in phase) is obtained from one entire line element.

Then, the U, V, and W-phase power generation line elements 104,
105 and 106, as shown in FIG.
Since they are shifted by 30 ^o , U, V, and W-phase power generation line elements 1
The signals generated from 04, 105 and 106 are shown in FIG.
As shown in, the sine wave is shifted by 120 ^° . These sine waves are generated by the amplifiers 141a, 141b, 141c (see FIG.
It is amplified by 1) and sent to the coil drive signal synthesizing circuit 151, where a coil current control signal as shown in FIG. 10 is generated for each phase of UVW. These control signals are sent to and amplified by the amplifiers 16a, 16b, 16c to excite the coils 17a, 17b, 17c of the respective phases.

Thus, it has become clear that the excitation timing control signal can be generated also by the power generating line element as shown in FIG. 8 in place of the conventional Hall element.
The power generation line element is formed by etching and is thin because it is a single layer, and therefore contributes to downsizing of the disk device.

Here, the etching positions of the power generating line elements 7a, 7b, 7c will be described. The conventional Hall element is an element that detects the strength of the magnetic field itself. On the other hand, the power generating line element detects an increase / decrease in the number of magnetic force lines passing through it, that is, because it is a differential output, it outputs a signal 90 ^° earlier than the Hall element. Therefore, the etching position of the power generation line element is 90 ^{° in} electrical angle compared to the mounting position of the conventional Hall element.
(Mechanical angle is 22.5 ^o ) It is necessary to wear it slowly.

FIG. 15 shows the power generating line elements 104, 105 and 10.
6 shows the positional relationship between 6 and the drive coil 102. First, one line segment in the radial direction of the U-phase power generation line element 104 is selected, and a straight line aa passing through the rotation center is drawn. Next, a line segment b-b overlapping with the W-phase power generation line element 106 and a line segment c-c overlapping with the V-phase power generation line element 105 are drawn so as to divide the circumference into six equal parts. U-phase coil 1
02a is arranged in a space having an extent of 60 ^° surrounded by the line segment bb and the line segment cc, and the V-phase coil has an extension of 60 ^° enclosed by the line segment aa and the line segment bb. And the W-phase coil is surrounded by a line segment c-c and a line segment a-a 60 ^°.
Is arranged in a space having a spread. When the motor drive circuit is turned on, the rotor rotates in the direction of the arrow in the figure.

When the timing position is detected by the Hall element as in the conventional example without using the power generating line element, the Hall element 12 is arranged at three positions indicated by X in the figure.
That is, the U-phase Hall element 500a is arranged on the line segment aa, the W-phase Hall element 500b is arranged on the line segment bb, and the W-phase Hall element 500c is arranged on the line segment cc. U-phase power line element 10
4 and the U-phase Hall element are the places where the U-phase Hall element should be arranged at the right side 22.5 ^{o in} mechanical angle from the midpoint of the radial line segment of the U-phase power generating line element as shown in the figure. It becomes such a positional relationship.

By the way, the generator element outputs a signal only when the magnetic field crosses it. In other words, the direction of the exciting current becomes unknown at the time of starting without rotation. This is because the power generation line element is not output at startup. Therefore, a separate starting circuit is required.

Here, the motor starting will be described. In the conventional motor, a current is passed through two of the three phases of the UVW of the drive coil to rotate the rotor, and the counter electromotive force generated in the remaining phases at this time is detected to detect the rotation direction at startup. Is checked. However, this method is not preferable because it causes switching noise. Therefore, so-called soft switching, in which a current is also applied to the other phases to excite them, is currently the mainstream. This soft switching control IC may be used to detect the rotation direction at startup for this embodiment. Further, in the present embodiment, since the drive coil 102 and the power generation line element for timing detection are different, noise is suppressed by using soft switching for the drive coil 102, and the rotation direction at the time of startup is detected at any time. The back electromotive voltage generated in the power generation line element of that phase may be used.

Next, a modification of the above embodiment is shown in FIG.
2, it demonstrates based on FIG.

This modification is similar to the FG shown in FIG.
The magnet 201 is eliminated, and further the W-phase power generation line element is eliminated. As shown in FIG. 12, the drive magnet 101 has 8 poles having an 8-pole fan-shaped pattern 101a. Even if the FG magnet is removed, the FG signal can be detected by the FG power generation line element 103 as shown in FIG. This is because the line element 103 provided on the innermost circumference on the stator side crosses the 8-pole magnetic field generated by the drive magnet 101. In FIG. 8, the W-phase power generation line element is shown in FIG.
Has been removed from the example of FIG. The W-phase signal is created by combining the U-phase and V-phase power generation line elements.

W = −U−V (where U, V and W are vectors.) The timing circuit of this modification does not require the W-phase generator line element and the W-phase generator line element amplifier in FIG. In front of the drive signal synthesizing circuit 151, a vector synthesizing circuit for synthesizing the W-phase signal by the above equation is added.

According to this modification, the FG magnet is not required and the drive magnet can be magnetized to the outermost circumference, so that the torque is increased. Also, if the FG magnet is made separately from the drive magnet, the number of parts is reduced, leading to cost reduction.

In the above embodiment, the present invention is applied to a spindle motor having a rotational position detecting device, which is a surface-opposing spindle motor, but the present invention is not limited to this. The present invention can be applied to a general electromagnetic rotating machine having a motor and a rotation position detecting device. When applied to a circumferentially opposed motor, it is necessary to arrange the line elements in the vertical direction as shown in FIG.

In the embodiment and the modified examples described above, in the n-pole brushless motor, n-phase power generating line elements are provided in place of the conventional Hall element, and sine wave signals from these power generating line elements are excited at the excitation timing. As a result, the Hall element is not needed, and the device can be made smaller (especially thinner) and at a lower cost. Particularly, in the face-to-face type motor, the three-phase power generating line elements can be spread in the plane, and the effect of thinning is remarkable.

[0036]

As described above, the present invention relates to a magnetic field generating means having a circumferential shape provided on the stator in an electromagnetic rotating machine composed of a roller and a stator, and the exciting currents of a plurality of phases. Magnetic field generating means for generating a rotating magnetic field by energizing the rotating magnetic field, a drive magnet which is provided on the rotor side in order to obtain a rotating torque from the rotating magnetic field, and which is multi-pole magnetized in the circumferential direction, and the rotor. Coil means for detecting a change in magnetic field generated when the driving magnet provided above rotates, the coil means having the power generation line element formed by etching on the rotor. And

That is, since the power generating line element is provided for detecting the excitation timing, it is possible to make the device thinner, and at the same time, the conventional excitation timing detection element such as a Hall element is not necessary, and the cost can be reduced. ..

[Brief description of drawings]

FIG. 1 is a plan view illustrating a structure of a conventional three-phase brushless motor.

FIG. 2 is a partial cross-sectional view of the motor shown in FIG.

FIG. 3 is a timing chart showing signals output from the Hall element of the motor shown in FIG.

FIG. 4 is a block diagram showing the configurations of an excitation timing detection circuit and an excitation circuit according to a conventional technique.

FIG. 5 is a timing chart of the exciting current according to the related art.

FIG. 6 is a sectional view of a motor according to an embodiment of the present invention.

FIG. 7 is a plan view of the rotor portion of the motor shown in FIG. 6, illustrating the magnetization pattern of the drive magnet.

8 is a diagram showing a power generation line element pattern of the motor of FIG. 7. FIG.

FIG. 9 is a timing chart showing a signal output from the power generation line element of the example motor.

FIG. 10 is a timing chart of the exciting current in the present embodiment.

FIG. 11 is a block diagram showing the configurations of an excitation timing detection circuit and an excitation circuit in this embodiment.

FIG. 12 is a plan view of a rotor portion of a motor according to another embodiment of the present invention.

FIG. 13 is a diagram showing a power generating line element pattern in the stator portion of the motor.

FIG. 14 is a diagram showing a positional relationship between a power generating line element and a magnet according to still another modification.

FIG. 15 is a diagram showing a positional relationship between a power generating wire element and a drive coil.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Driving magnet, 2 ... FG magnet, 4 ... Rotor yoke, 103, 104, 105, 106 ... Generating wire element part, 101b ... FG magnetization pattern, 102 ... Driving coil

Claims (5)

[Claims] 1. An electromagnetic rotating machine comprising a rotor and a stator, wherein the magnetic field generating means is provided on the stator and has a circumferential shape, and a rotating magnetic field is generated by supplying exciting currents of a plurality of phases. It is generated when the magnetic field generating means, the multi-pole magnetized drive magnet provided on the rotor side to obtain the rotational torque from the rotating magnetic field, and the drive magnet provided on the rotor rotate. An electromagnetic rotating machine comprising coil means for detecting a change in a magnetic field, the coil means having its power generating line element formed by etching on the stator. 2. The electromagnetic rotating machine according to claim 1,
The coil means detects a signal having a frequency equal to half the number of poles of the drive magnet during one rotation of the drive magnet. 3. The electromagnetic rotating machine according to claim 1,
Each of the power generating line elements of the coil means has a rectangular shape,
The number of intercepts of all the power generating line elements in the direction orthogonal to the magnetic field formed by the drive magnet is equal to the number of magnetization reversals of the drive magnet. 4. The electromagnetic rotating machine according to claim 1,
With respect to the output of each power generating line element of the coil means, when one cycle of the output signal of the power generating line element is 360 degrees and the number of phases of the magnetic field generating means is n, the phases are separated by 360 / n degrees. There is. 5. The electromagnetic rotating machine according to claim 1,
The mounting position of the power generation line element is delayed by 90 ^° from the magnetization reversal position of the drive magnet.