JPH0442764A - Measuring device for magnetization distribution of brushless motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magnetization distribution measuring device for a brushless motor, and particularly to a magnetization distribution measuring device for a brushless motor, in particular a device for measuring magnetization distribution of a brushless motor. On the other hand, a brushless motor moves the detection head of the magnetic flux density measurement device in the radial direction one step per rotation of the rotor, and collects magnetic flux density data while referring to pulses generated from a rotary encoder as a rotation angle as a rotation angle. This invention relates to a magnetization distribution measuring device.

[Background Art] In recent years, with the rapid development of audio equipment, video equipment, computers, etc., there is a growing demand for higher quality as their performance improves.

In particular, motors installed in AV equipment (audio visual equipment) are required to have small rotational irregularities, high efficiency, and stability.

However, the tie-left drive system has started to attract attention as a drive system, and a motor with low speed and extremely small rotational irregularities is required.The axial flux brushless motor is the best motor to meet this requirement, and this type of motor is suitable for AV equipment. Motors are commonly used.

That is, as shown in the overall cross-sectional view of the brushless motor in Figures 2 fa) and (b), the most commonly used three-phase bipolar 8iFi! A brushless motor has a flat outer shape with an axial dimension smaller than its diameter.

In this case, the rotor 122 is formed of a disk-shaped magnet, and has a magnetized configuration called axial flux, which is magnetized in the direction of a rotor axis 122b perpendicular to the surface of the disk.

The rotor shaft 12 of this rotor magnet 122a
2b is rotatably supported via bearings 127a and 127b inserted into a boss 125a of the housing 125.

Furthermore, a flange 125 formed on the housing 125
An iron substrate (hereinafter referred to as yoke 98) is fixed to the upper surface of b, and an insulating surface 98a of this yoke 98 has 6
The stator 97 is composed of several fan-shaped coils 96 arranged in the shape of an orange slice. And rotor magnet 1
The lower surface of 22a is magnetized in a fan shape with 8 poles, and this magnetized surface 1
The rotor magnet 122a is arranged so as to form a slight gap δ between the coil 96 of the stator 97 and the upper surface of the coil 96 of the stator 97.
is supported.

Further, the coil 96 has a positional relationship of ±7.5° based on the position where the magnetic pole and the center of the coil 96 overlap.
The torque-generating conductor (straight portion) of the coil overlaps a lot with the magnetic pole boundary, making the torque generated by the coil unstable, so it is disconnected from the motor circuit.

On the other hand, one phase of the six coils 96 is obtained by connecting two coils 96 facing each other in series around the rotor shaft 122b, and two phases that do not meet the above conditions are connected in series, and the magnetic pole ( The direction of the current is controlled so that rotational torque is generated in one direction depending on the polarity (N pole, S pole).

In this type of motor, one of the three phase coils is always at rest, and this switching is performed by the driver IC every time the rotor 122 rotates 15 degrees.

In other words, torque is generated by each coil acting on all the magnetic poles of the rotor magnet at the same time, and as the rotor magnet rotates, the flow through the SWindows changes from the coil forming one pole to the next. The coils forming the poles are sequentially switched, and each coil is responsible for generating torque in turn. The coil current of one pole is switched between positive and negative directions depending on the polarity of the approaching magnetic pole, and the switching of this current between positive and negative is performed at a synchronous frequency determined by the number of poles of the rotor magnet and the rotational speed of the motor.

In this case, the torque varies depending not only on the strength of the main magnetic flux and the current in the coil, but also on the relative positional relationship between the magnetic poles of the rotor magnet 122a and the coil 96. In response to the changes, the current in each coil must be appropriately controlled so that the resulting torque generated at any moment is always constant.

However, if this torque changes depending on the positional relationship of the rotor magnet 122a, the rotational speed of the motor changes instantaneously, causing so-called wow and flutter. AVI
This wow and flutter is fatal to the motor, so it is necessary to suppress torque fluctuations as much as possible.

This control is performed by the Hall element 100 and the coil current control circuit, and the Hall element 100 is connected to the rotor magnet 12.
The position of the magnetic pole 2a is detected and, based on the signal, appropriate current is distributed to the electronic circuit or the coils of each phase.

Here, in order for the torque generation sequence to be performed accurately, the arrangement positions of the magnetic poles and Hall elements 100 must be accurate. This disturbs the periodicity of the sequence for controlling the coil current, and causes the torque to fluctuate over time within one revolution of the motor.

Further, as the rotor magnet rotates, the magnetic poles that generate torque change sequentially, but if there is any unevenness in the magnetization of the magnet, this can immediately cause fluctuations in the rotational speed.

Therefore, it is necessary to measure the magnetization distribution state of the rotor magnets of various brushless motors in advance and collect data on magnetic flux density.

In this case, when measuring the magnetization distribution of the rotor magnet 122a, the detection head of the magnetic flux density measuring device is moved at a constant speed in the radial direction with respect to the rotor magnet 122a while the rotor magnet 122a is rotating at a constant speed, It is configured to obtain the magnetization distribution using the detected t\rad output voltage as a measurement value.

[Problems to be solved by the invention] However, such conventional magnetization distribution measuring devices,
Since it is difficult to control the rotational speed of the rotor magnet to a constant speed, the method of showing the magnetization distribution as a function of time has the disadvantage of large errors, and the magnetic flux data, that is, the output voltage of the magnetic flux density measurement device, is Is it necessary to set the rotation speed of the rotor magnet low in order to measure without being influenced by had.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rotation detector in a part of the rotor support means, and to move the detection head of the magnetic flux density measuring device in a radial direction with respect to the rotor step by step every rotation of the rotor. By doing so, it is an object of the present invention to provide a brushless motor magnetization distribution measuring device that can measure the magnetization distribution of a rotor with high precision.

[Means for Solving the Problems] In order to achieve the above object, the rotor of a brushless motor is rotatably supported, and a detection head is moved stepwise in the radial direction with respect to the rotor for each rotation of the rotor to move the detection head over the rotor. The brushless motor magnetization distribution measuring device of the present invention, which measures the magnetization distribution of a brushless motor, includes a rotor support means for rotatably supporting the rotor, a rotation detector provided on the support means, and a yoke for the rotor. yoke support means for positioning and supporting the
a magnetic flux density measuring device that measures the magnetization distribution of the rotor;
The detection head of this magnetic flux density measuring device is characterized by comprising a moving means that moves in the radial direction with respect to the rotor and in the rotor axial direction of the rotor.

[Function] The brushless motor magnetization distribution measuring device according to the present invention has the following features:
The detection head of the magnetic flux density measuring device is moved step by step in the radial direction of the rotatably supported rotor by means of a moving means for each rotation of the rotor, and pulses generated from a rotary encoder as a rotation detector provided in the support device are detected. By collecting data on the magnetic flux density while referring to the rotation angle, highly accurate measurement of the magnetization distribution can be achieved.

[Embodiment] Next, an embodiment of the brushless motor magnetization distribution measuring device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall view of a brushless motor magnetization distribution measuring device showing an embodiment of the present invention.

In this figure, reference numeral 10 indicates a rotor support means, which is rotatably vertically supported on a base 13 and has a main shaft 16 having an engaging portion 16a (concave center) at its tip. , is located on the same axis as the main shaft 16 and is supported rotatably and slidably in the axial direction, and has the main shaft 1 at the tip.
Engagement part 18a (concave center) opposite to engagement part 16a of No. 6
An auxiliary shaft 18 provided with a
8, and a weight 22 (see Fig. 3) that engages with the upper end of the auxiliary shaft 18 and presses the auxiliary shaft 18 in the axial direction. has been done.

Further, reference numeral 122a indicates a rotor magnet, and this rotor magnet 122a is made of a ferrite material and is formed into a disk shape, and is composed of a pair of rotor shafts 122b provided above and below the center of this disk. The magnet 122a is rotatably supported on the same line as upper and lower supporting means 10, which will be described later.

That is, the housing 104 is inserted into and fixed to the through hole 102 formed in the base 13 at the opening of the case 103.
is inserted into the housing 104, and a flange 104a formed on the upper edge of the housing 104 is fixed with bolts.

A pair of bearings 106a are provided above and below the through hole formed in the center of the housing 104.

106b is inserted, and these bearings 106a, 10
A main shaft 16 is rotatably supported by the main shaft 6b.

In this case, a pulley 108 is fixed to the main shaft 16 that has passed through a bearing 106b that supports the lower part of the main shaft 16, and a boss portion of this pulley 108 allows the bearing 106 to
The inner ring of b is pressed in the axial direction to give it a preload.

Furthermore, the upper part of the main shaft 16 is similarly supported by a bearing 106b, and a cap 110 is inserted and supported on the upper part of the main shaft 16 that has passed through the bearing 106b.

This cap 110 has a rotor 122 on its side.
A pin 112 that transmits rotation to is provided to protrude in the radial direction.

A preload collar 114 inserted on the main shaft 16 between the cap 110 and the upper bearing 106a is connected to the wave washer 1.
The inner ring of the bearing 106a is elastically pressed in the axial direction through the bearing 106a to apply a preload to it.

The cap 110 has a bottle 112 protruding from its side surface in the radial direction, and a bracket 118 with a vertical pin 117 embedded therein is attached to the rotor shaft 122 to engage with the bottle 112.
A rotation transmitting means 10 is configured which is fixed to the lower end of b and transmits the rotation of the main shaft 16 to the rotor 122. As a result, the rotor 122 is rotated together with the rotation of the main shaft 16, which is transmitted from a drive source (not shown) through the rotation transmission means 10, which is not decelerated by the pulley 108.

On the other hand, the rotor support means 10 is also placed on the upper part of the rotor shaft 122b.
is provided. That is, an auxiliary shaft 18 having a concave center 18a formed at its lower end so as to face the concave center 16a of the main shaft 16 is arranged on the same axis as the main shaft 16, and this auxiliary shaft 18 is arranged on the same axis as the main shaft 16. It is supported rotatably and slidably in the axial direction via a linear ball bearing 24 inserted into the shaft.

Note that this linear ball bearing 24 is normally commercially available, and its outer ring is fixed in the insertion hole 26 of the support body 20, and a plurality of balls are rotatably supported therein via a cage. It has a structure that allows

In this way, both the upper and lower ends of the rotor shaft 122b are connected to the main shaft 1.
6 and the auxiliary shaft 18, or the upper end of the auxiliary shaft 18 is fitted with an appropriate weight weighed in advance to apply an appropriate pressing force to both the upper and lower ends of the rotor shaft 122b. The weight 22 is removably inserted and thereby properly presses both ends of the rotor shaft 122b to achieve stable support of the rotor 122.

In this case, a rotary encoder 16b is connected to the lower end of the main shaft 16 via a coupling 16a, and this encoder 16b generates pulses divided into a plurality of pulses for one rotation of the rotor 122, and generates pulses corresponding to one rotation of the rotor 122. When the measurement is completed, the probe 54 of the measuring instrument 50 is moved one step in the radial direction of the rotor 122. By sequentially repeating this process, the state of magnetic distribution on the coordinate-divided rotor 122 can be accurately measured.

On the other hand, in FIGS. 1 and 3, the yoke 98 is arranged with a predetermined gap (magnetic gap length) relative to the magnetized surface 122C of the rotor magnet 122a, with the brushless motor being arranged in the same manner as when it is not assembled. In order to set this, it is attached and supported on the bottom of the yoke support means 14 so as to generate a magnetic field between the rotor magnet 122a and the yoke 98.

The yoke support means 14 is configured to be adjustable with respect to the rotor magnet 122a in order to cope with changes in the mutual positional relationship between the rotor magnet 122a and the yoke 98 depending on the type of brushless motor.

That is, this yoke support means 14 is provided with a column 28 erected on the base 13 (see FIG. 3) and a linear force fixed to the front side of this column 28 in order to be opposed to the rotor magnet 122a at a predetermined distance. Idrail 30
A base plate 32 with a base plate 32, a slide table 34 slidably fitted into the linear guide rail 30, and a plurality of pin holes 38 fixed on the slide table 34 and arranged in pairs on the upper surface. It includes a table 36 arranged in parallel columns at equal pitches, a pair of pins 39 protruding from the end surface to selectively engage with a pair of pin holes 38 on the table 36, and a yoke 98 on the lower surface.
The bracket 27 has a flat surface to which it is attached.

Therefore, when setting the magnetic gap length, it is possible to selectively engage and position the retaining pins 39 of the bracket 27 in the pair of pin holes 38 in the optimal position of the table 36.

In this case, in order to further finely position the yoke support means engaged with the pin hole 38, the fine movement means for finely moving the yoke support means is constructed as follows.

That is, a locking piece 40 is provided protruding from the upper side surface of the slide table 30 (on the left side), and a block 4 is provided below the locking piece 40 at a position facing and spaced a predetermined distance from the locking piece 40.
2 is fixed on the base plate 32.

One end of a cylindrical nut body 44 is fixed to this block 42, and a precision screw rod 46 (configuration similar to a micrometer) is attached to this nut body 44.
are screwed together, and by rotation of the knob 48 provided at the end of the nut body 44, the threaded rod 46 is moved against the locking piece 40.
It is configured to be able to move forward and backward.

In this case, the slide table 34 is urged downward (towards the base) by the tension of a tension spring (not shown) provided inside, and the downward movement of the slide table 34 due to this urging force is integral with this. This is prevented by elastically abutting the tip of the screw rod 46 against the lower surface of the locking piece 40, which has a similar structure.

Therefore, by rotating the knob 48 of the screw rod 46, the table 36 having a yoke attached to its lower surface can be slightly moved in the vertical direction, and the digit 1 of the table 36 can be appropriately set.

In this way, the positional relationship of the yoke with respect to the different rotor magnets of various brushless motors can be set in a short time and with high precision.

Next, based on FIGS. 1 and 3, the magnetic flux density measuring device 50 is
I will explain about it.

That is, this measuring device 50 includes a magnetic detection head 52, a rod-shaped flattened probe 54 that extends from the tip of the magnetic detection head 52 and has a Hall element embedded therein, and outputs the magnetic flux density detected by the Hall element. and an output device (not shown).

The magnetic detection head 52 configured in this way is supported by the moving means 55 and is attached to the rotor magnet 1 which has already been set.
The probe 54 is moved in the radial direction of the rotor 122 with a minute interval relative to the magnetized surface 122C of the magnet 22a.

As shown in FIGS. 4 to 6, this moving means 55 is inserted into a column 58 erected on the base 13 and a linear guide rail 60 attached to this column 58, and is guided to move up and down. L-shaped support stand 6 fixed on stand 61
2, and a magnetic detection head 5 that is slidably guided by a linear kite rail 64 fixed on the horizontal surface of the support base 62.
2 and a rotor magnet) 122
It is composed of a feeding mechanism which is a moving means 55 that moves forward and backward with respect to the @magnetic surface of a.

Further, on the base 13, a screw shaft 68 with a knob 67 at the tip is erected near and parallel to the support column 58, and this screw shaft 68 is connected to a nut fixed perpendicularly to the rear side surface of the support base 62. 70, and the magnetic detection head 52 is configured to be movable up and down together with the support base 62 via this nut 70 (see FIGS. 5 and 6).

A retaining means 56 is provided on the upper surface of the holder 66, which is placed so as to be movable forward and backward via the linear guide rail 64 of the support base 62.

In other words, as shown in FIGS. 1, 4, and 5, this engaging means 56 is connected to an L-shaped bracket 78 fixed to the upper surface of the holter 66 and a vertical piece of the L-shaped bracket 78 that faces the L-shaped bracket 78. a leaf spring 84 fixed to the end of the horizontal piece;
An adjustment screw 82 that is screwed into a screw hole passing through a vertical piece of the bracket 78 and has a knob 80 attached to its tip, and an engagement pin 86 that is implanted in a block 88 that is fixed to the inner surface of a leaf spring 84.
The engagement pin 8 is connected to the screw shaft 74 via this block 88.
6, a compression coil spring 92 is inserted between a flange 90 at the tip of the adjusting screw 82 and the block 88.

In this case, the engagement pin 86 implanted in the block 88 is slightly inclined by fJA in accordance with the lead angle of the screw 76 in order to engage with the screw 7!476 screwed on the outer periphery of the screw shaft 74. . Further, the engagement pin 86 is configured to be elastically pressed into engagement with the screw shaft 74 by the action of the biasing force of the compression coil spring 92 and the plate spring 84.

The pressing force of the engaging pin 86 can be adjusted by rotating the adjusting screw 82 (see FIG. 4).

Therefore, the driving force of the output shaft of the stepping motor 72 can be set within a predetermined transmission torque so that the holder 66 supporting the detection head 52 moves in the axial direction with an appropriate thrust force.

In this case, as shown in FIG.
The tip portion of the detection head 52 is positioned and set at an appropriate position with respect to the rotor 122 as the object to be detected.

When detecting the magnetization distribution of the rotor magnet 122a, the tip of the probe 54 of the detection head 52 can be appropriately moved in the axial direction with respect to the rotor magnet 122a to set an appropriate initial position.

Furthermore, the tip of the probe 54 and the rotary magnet 12
The vertical spacing between the magnetized surface of the rotor 122 and the magnetized surface of the rotor 122 can be finely adjusted by rotating a knob 67 of a screw shaft 68 installed on the base 13, and set to an appropriate spacing with respect to the detected magnetized surface of the rotor 122. can.

In this way, the probe 54 of the magnetic detection head 52 set at an appropriate position can accurately measure magnetism by moving in the axial direction under the rotational control of the stepping motor 72 with respect to the rotationally driven rotor 122.

The linear movement end of the globe 54 is controlled by a pair of limit switches 62a arranged on the front surface of the support base 62 to detect which dog 66b is fixed to the front and back of the lower surface of the holder 66.
, 62b detects the forward and backward movement end of the detection head (see FIGS. 1 and 5).

In this way, the holder 66 supporting the magnetic detection head 52
By configuring the engaging means 56 to be engaged with the shutter 76 of the screw shaft 74 of the stepping motor 72 serving as the driving part, the transmitted torque is appropriately limited and stable feed is achieved. You can get the aircraft width.

[Effects of the Invention] As is clear from the above-mentioned embodiments, the brushless motor @magnetic distribution measuring device according to the present invention includes a rotation detector in the rotor magnet support means, and also has a rotation detector in the radial direction with respect to the rotor magnet. By configuring the detection head of the magnetic flux density measuring device to be moved step by step for each rotation of the rotor magnet using a moving means, the magnetic distribution of the rotor magnet, which determines the rotational characteristics of a brushless motor, can be measured with high precision. Furthermore, it has many advantages, such as being able to easily handle magnetization distribution measurements of rotor magnets of brushless motors of various sizes.

Although the preferred embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a brushless motor magnetization distribution measuring device showing an embodiment of the present invention, FIG. 2 is an overall sectional view of the brushless motor, and FIG. 2(a) is a longitudinal sectional view thereof. 2
Figure (b) is a sectional view taken along line A-A in Figure 2 (a), Figure 3 is an overall perspective view of the magnetization distribution measuring device, and Figure 4 is a partial enlargement of the feed mechanism used in the magnetization distribution measuring device. Perspective view, Figure 5 is the first
6 is a sectional view taken along the line B-B in the figure, and FIG. 6 is a view taken along arrow C in FIG. 10... Rotor support means 13... Base 14...
-Yoke support means 16...Main shafts 16a, 18a...Engaging portion (concave center) 18...Auxiliary shaft 20...-Support body 22...Weight 24...Linear ball bearing 26...・Insertion hole 27...bracket 28
... Yoke 30 ... Linear kite rail 32 ... Base plate 34 ... Slide table 36 ... Table 38 ... Pin hole 46 ...
- Screw rod 50... Measuring device 52... Magnetic detection head 54... Probe 55... Engagement means
56...Transportation means 58...Strut
60... Kite rail 62... Support stand 6
4... Kite rail 66... Holder 68
．． 74...Screw shaft 72...Stepping motor 76...Screw shaft 82...Screw shaft 86...
・F pin 97...Stator 100...Hall element 122a...Rotor magnet 122b...Rotor shaft 96...Coil 98...Yoke 122...Rotor 122C...Magnetized surface \, ~-/ FIG, 2 (G) (b) FIG- FIG Procedural amendment (Rei) 1. Display of the case 1990 Patent Application No. 148710 2 Title of the invention 1 Brushless motor magnetization distribution measuring device 3 Person making the correction Relationship to the case Patent applicant address 167 Higashi-Ome-chome, Ome-shi, Tokyo 1 Name: Nippon Chemi-Con Co., Ltd. Representative Toshiaki Sato 4, Agent 6, Subject of amendment

Claims (1)

[Claims] (1) rotatably supports the rotor of the brushless motor,
In a brushless motor magnetization distribution measuring device that measures the magnetization distribution on the rotor by moving a detection head stepwise in the radial direction with respect to the rotor every rotation of the rotor, a rotor support means for rotatably supporting the rotor; , a rotation detector provided in the support means, a yoke support means for positioning and supporting the yoke at a predetermined position with respect to the rotor, a magnetic flux density measuring device for measuring the magnetization distribution of the rotor, and the magnetic flux density measuring device. 1. A magnetization distribution measuring device for a brushless motor, comprising a moving means for moving the detection head in the radial direction with respect to the rotor and in the rotational axis direction of the rotor.