JP2003018774A - Dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cogging torque of a DC brushless motor with a rotor comprising permanent magnet which is magnetized with N-poles and S-poles alternately in the circumferential direction. SOLUTION: In the DC brushless motor, comprising a stator 22 which is disposed with a stator yoke 25 comprising a plurality of core slots 26 on which coils 27 are wound, respectively; and a rotor 23, which has magnets 28, which are disposed rotatably facing the stator 22, and on which N-poles and S-poles are alternately magnetized in the circumferential direction, when an interval between the maximum value PH and the minimum value PL of magnetic flux density, which makes a boundary position P0 between the N-pole and the S-pole the center, is T1 , and a magnetizing period for a pair of N-pole and S-pole is T0 , magnetization distribution of magnets 28 is set so that a ratio (T1 /T0 ) between the interval T1 and the magnetizing period T0 becomes 1/3 to 1/2.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to a DC brushless motor.
N pole and S pole were alternately magnetized in the circumferential direction
DC brushless motor having a rotor composed of permanent magnets
About. [0002] 2. Description of the Related Art FIG. 5 shows a conventional DC brushless device.
1 shows a motor 1. DC brushless motor 1
Generally, it is composed of a stator 2 and a rotor 3.
You. [0003] The stator 2 has a stator yaw on a base 4.
The lock 5 is fixed. This stator yaw
The core 5 has, for example, a 12-pole core slot 6 formed therein.
Each core slot 6 has a coil 7 wound around it
It has been. The rotor 3 has a bush-shaped rotor output section 9.
The rotor output section 9 is erected on the base 4
By being supported by the stator shaft 14, the stay
It is configured to be rotatable with respect to the table 2. Also low
The magnet 3 is provided with an annular magnet 8.
The net 8 is the core slot 6 of the stator yoke 5 described above.
It is configured to confront with. The magnet 8 has a north pole and a south pole which alternate in the circumferential direction.
Permanent magnets magnetized with each other. In the example shown in FIG.
The poles and S poles are magnetized so that the total is 16 poles. Yo
Drive current from the drive control circuit (not shown) to each coil 7
, The core slot 6 has a predetermined timing.
Excited by As a result, the magnet 8 is biased to rotate.
This rotation is output from the rotor output unit 9. FIG. 7 shows a magnet for magnetizing the magnet 8.
The magnetic device 10 is shown. The magnetizing device 10 has a cylindrical base.
13 provided with a magnetizing coil 11 and a magnetizing yoke 12
It has been. The cylindrical base 13 is made of iron having a cylindrical shape.
Member. Magnet 8 before magnetization (hereinafter, this
Is referred to as a magnet base material 8A).
It is arranged on the periphery. Magnetizing coil 11 and magnetizing yoke 12
Are embedded in the cylindrical base 13.
However, the magnet base 8A of the magnetized yoke 12
The facing surface is exposed, and
The configuration is such that a magnetic field can be applied. The magnetizing coil 11 and the magnetizing yoke 12 are
The number of poles for magnetizing the gnet 8 is provided. Immediately
In order to magnetize the magnet substrate 8A with 16 poles,
Indicates that the magnetizing device 10 has 16 magnetized coils 11 and magnetized
A yoke 12 is provided. Then, magnetization is applied to the magnet substrate 8A.
When performing, the magnetic field direction of each adjacent magnetized yoke 12
Are applied to the magnetized coil 11 so that
Do. As a result, the magnet base material 8A becomes N
Pole and S pole are alternately magnetized to 16 poles, producing magnet 8
Is done. [0010] FIG. 6 is a schematic diagram showing a conventional method.
Of the magnet 8 applied to the brushless brushless motor 1
It is a figure for explaining magnetization distribution. In the figure, the vertical axis
The magnetic flux density is taken, and the rotor axis is taken on the horizontal axis. Ma
In the same figure, one magnetization period T of the S pole and the N pole is shown.₀(45deg)
Is shown. As shown in FIG.
The magnetized distribution of the magnet 8 disposed on the
Boundary position with S pole (arrow P in the figure₀The rotor angle indicated by
22.5deg), the magnetic flux density changes rapidly
ing. Specifically, the boundary position P₀Magnetic around
Minimum value of bundle density P_LAnd the maximum value P _HT₂(After
Bottom, local minimum interval T₂), The magnetic flux density is short
Large maximum minimum interval T₂Minimum value P_LFrom the maximum value P_HTo
It is changing rapidly. Now, one magnetization cycle T₀Maxima and minima for
Interval T₂Ratio (T₂/ T₀) Is obtained by the example shown in FIG.
Is the ratio (T₂/ T₀) Is about 1/10. In addition,
In the case of the conventional DC brushless motor 1,
Ratio (T₂/ T₀In most cases, the value of
Was. However, the magnet 8 shown in FIG.
Short rotor angle interval T₂Large magnetic flux density inside
The changing area (hereinafter, this area T)₂The magnetic flux density change area
) Is present when the rotor 3 rotates.
The fluctuation of the rotation torque occurs. This rotation torque change
The movement becomes cogging torque, and the DC brushless motor 1
There is a problem that rotation accuracy and rotation stability are impaired.
Was. The present invention has been made in view of the above points.
Yes, DC brushless that can reduce cogging torque
An object is to provide a motor. [0015] Means for Solving the Problems To solve the above problems,
In the present invention, a plurality of coil windings in which a coil is wound
A stator having a wire portion, and in a state facing the stator,
Rotatably arranged, N pole and S pole alternate in the circumferential direction
And a rotor made of permanent magnets magnetized
In a DC brushless motor, the boundary between the N pole and the S pole
The distance between the maximum and minimum values of the magnetic flux density around the boundary position
To T₁And the magnetization period of a set of N and S poles is T₀age
The interval T₁And the magnetization period T₀Ratio (T₁/
T₀) Is 1/3 or more and less than 1/2.
It is characterized in that the magnetization distribution of the magnet is set.
You. As described above, the maximum value and the minimum value of the magnetic flux density
Interval T₁And the magnetization period T of a set of N and S poles₀When
Ratio (T₁/ T₀) To be at least 1/3 and less than 1/2
By setting the magnetization distribution, the boundary position between the N pole and the S pole
Magnetic flux density changes in
You. As a result, the boundary position between the north pole and the south pole is relatively controlled.
Suppresses the occurrence of cogging torque when passing
can do. [0017] Next, an embodiment of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows a DC brush according to an embodiment of the present invention.
FIG. 2 is a perspective view of the motor 20 and FIG.
Enlarge the stator 22 and magnet 28 of the motor 20
FIG. The DC brushless motor 20 is roughly
It is composed of a stator 22 and a rotor 23. S
The stator 22 has a stator yoke 25 fixed on a base 24.
The configuration is fixed. The base 24 is a metal plate-like substrate,
A print arrangement is provided at a position where the stator yoke 25 is arranged.
A line portion 34 is formed. This printed wiring section 34
Is based on full flat cable (FFC) 35
24 is drawn out. See below
The end line of the coil 27 is electrically connected to the printed wiring portion 34.
Continue and draw from FFC35
Have been. The FFC 35 is a DC brushless motor 20
Connected to a drive control device (not shown)
It is. In this embodiment, the stator yoke 25 is 12
A core slot 26 is formed for each core slot.
The coil 27 is wound around the coil winding portion 33 of the
2 (illustration of the coil 27 is omitted in FIG. 2).
The stator yoke 25 is formed by stacking a plurality of thin yoke base materials.
It has a layered configuration. That is, the core throttle 26
As a laminated core, eddy current loss is suppressed.
Have been. The coil wound around the core throttle 26
The end line of the screw 27 is disposed on the base 24 as described above.
Connected to the printed wiring section 34. In addition, this implementation
The DC brushless motor 20 according to the example has a three-phase motor structure.
It has been. The rotor 23 is disposed inside the stator 22.
It is the configuration which was done. That is, the DC power supply according to the present embodiment
The brushless motor 20 is an inner rotor motor.
is there. However, as will be clear from the description below,
The application of the invention is limited to motors having an inner rotor structure.
But also for motors with an outer rotor structure.
It can be used. The stator 22 is generally a magnet 2
8, rotor output section 29, rotor base 30, etc.
It is configured. The rotor base 30 is, for example, a rolled steel plate.
And a ring-shaped magnet 28
Is fixed to the inner peripheral portion of the. The rotor base 30 has a center
A brush-shaped rotor output section 29 is provided.
The data output section 29 is a stator shuff
, And is configured to be supported by the bearing 31. Also, the stator
A bearing is provided between the shaft 31 and the rotor output portion 29.
A tag 32 is provided. As a result, the rotor 23
It is configured to be rotatable with respect to the theta 22. The magnet 28 is provided with the above-described stator yaw.
Is configured to face the core slot 26 of the
You. This magnet 28 has an N pole and an S pole alternately arranged in the circumferential direction.
It is a permanent magnet that is magnetized. The magnet according to the present embodiment
At 28, the magnetic poles are magnetized so that the N and S poles are 16 poles in total.
Have been. The attachment of the magnet 28, which is an essential part of the present invention, is performed.
The magnetic distribution will be described later for convenience of explanation.
You. DC brushless motor 2 constructed as described above
0, the drive control circuit (not shown)
Drive current to each coil 27 via the printed wiring section 34
Is supplied, the core slot 26 has a predetermined timing.
And the magnet 28 is energized by rotation.
Thus, the rotor 23 rotates. The rotation of the rotor 23
Transmitted to an external driven device via the data output unit 29.
You. FIG. 4 is a view showing a state in which the magnet 28 is magnetized.
The magnetizing device 40 is shown. Basic configuration of magnetizing device 40
Differs greatly from the magnetizing device 10 shown in FIG.
No magnetizing coil 41 and magnetizing yoke are mounted on the cylindrical base 43.
42 are provided. The cylindrical base 43 is made of iron having a cylindrical shape.
And a magnet 28 (magnet 28) before magnetization.
The base material 28A) is disposed on the inner peripheral portion during the magnetization process.
You. The magnetized coil 41 and the magnetized yoke 42 have a cylindrical base.
43 is embedded. However,
The surface of the magnetized yoke 42 facing the magnet substrate 28A is
Exposed, applying magnetic field to magnet substrate 28A
It is a configuration that can be done. The magnetizing coil 41 and the magnetizing yoke 42 are
The number of poles for magnetizing the gnet 28 is provided.
That is, the magnet base material 28A is magnetized with 16 poles.
In other words, 16 magnetizing coils 41 and
A magnetized yoke 42 is provided. Then, the magnet 28A is magnetized.
Is performed, the magnetic field direction of each adjacent magnetized yoke 42
Apply current to magnetized coil 41 so that directions are opposite to each other
Perform As a result, the magnet base material 28A moves in the circumferential direction.
The N and S poles are alternately magnetized to 16 poles, and the magnet 28
Is manufactured. At this time, the magnet 28 used in this embodiment is
The magnetizing device 40 that manufactures the
The separation distance (that is, the portion where the magnetized yoke 42 is not provided)
Minute distance. This distance is indicated by an arrow W1 in the figure).
The magnetic device 10 is set to be short and wide. Immediately
That is, as shown in FIG.
The separation distance of the magnetized yoke 12 in contact is W2 (the distance indicated by the arrow).
In this case, the relationship W2> W1 is satisfied.
Have been. FIG. 3 shows a magnetizing device 40 constructed as described above.
Magnetization distribution of magnetized magnet 28 according to the present embodiment
FIG. In the figure, the vertical axis indicates the magnetic flux density
And the horizontal axis represents the rotor angle. Also, in the same figure
In addition, one magnetization period T of S pole and N pole₀(45deg)
ing. As shown in FIG.
The magnetization distribution of G28 has a smooth sinusoidal distribution characteristic.
Is shown. At this point, the rectangular wave shape shown in FIG.
Significantly different from the distribution characteristics of the conventional magnet 8 presented
I have. Now, in FIG. 3, the boundary between the N pole and the S pole
Position (arrow P in the figure)₀The rotor angle indicated by is about 22.5deg
Minimum value P of the magnetic flux density around_LAnd the maximum value P_HWhen
The interval of T₁(Maximum minimum interval T₁), The magnetic flux density
Is a relatively long local minimum interval T ₁Minimum value P_LFrom pole
Large value P_HIn addition, it changes more smoothly than before. Now, one magnetization cycle T₀Maxima and minima for
Interval T₁Ratio (T₁/ T₀) Is obtained by the example shown in FIG.
Is the ratio (T₁/ T₀) Was about 3/8. And
When this DC brushless motor 20 was driven, FIG.
5 to FIG.
30% to 50% reduction in cogging torque compared to
I was able to. This is the magnet 2 used in this embodiment.
8 is the minimum value P of the magnetic flux density as shown in FIG._LFrom pole
Large value P_HRotor angle interval T up to₁Is long,
This is because the change in the magnetic flux density becomes a smooth change. Yo
When the rotor 23 rotates, the stator 22 and the rotor 2
No large rotation torque fluctuation occurs in 3
In addition, generation of cogging torque can be suppressed. This
As a result, the rotation accuracy and the rotation of the DC brushless motor 20 are improved.
The rolling stability can be improved. As described above, one magnetization cycle T₀Poles against
Large minimum interval T₁Is set to be longer than before
Can suppress the occurrence of cogging torque
You. However, one magnetization cycle T₀Maxima and minima for
Interval T₁If the DC brushless motor is set
20 is the torque for driving the driven equipment (output torque)
Will decrease. The present inventor has determined that one magnetization cycle T₀Maximum against
Minimum interval T₁An experiment was carried out to change. as a result,
One magnetization cycle T₀The local minimum interval T for₁Ratio (T₁/
T₀) Is less than 1/3, cogging torque may be generated.
Cannot be effectively controlled. Also, one magnetization cycle T₀To
Maximum local minimum interval T₁Ratio (T₁/ T₀) Is less than 1/2
Above, the generation of cogging torque can be effectively suppressed
However, the output torque of the DC brushless motor 20 is significant.
It will be much lower. Therefore, the local minimum interval T₁And a set of N poles
Period T between S and S pole₀And the ratio (T ₁/ T₀) To 1/3
The magnetization distribution of the magnet 28 is set to be less than 1/2.
By setting, the generation of cogging torque is effectively suppressed.
Control the output torque.
Can be. The maximum and minimum intervals T₁To change the
Of the adjacent magnetized yokes 42 described with reference to FIG.
It can be easily changed by changing the distance W1.
it can. In other words, the longer the distance W1 is, the larger the local minimum is.
Interval T₁Becomes shorter, and conversely, the shorter the separation distance W1 is,
Large minimum interval T₁Becomes longer. This is because the separation distance W1 of the magnetized yoke 42 is
If it becomes shorter (that is, the magnetized yoke 42 becomes longer in the circumferential direction).
), The magnetic field during magnetization is dispersed, and the magnetic flux density decreases.
Therefore, the magnetization distribution becomes smooth as shown in FIG.
On the contrary, the separation distance W1 of the magnetized yoke 42 becomes longer (immediately.
(The magnetized yoke 42 becomes shorter in the circumferential direction).
Since the magnetic field is concentrated and the magnetic flux density increases,
This is because a rapidly changing magnetization distribution is formed as
You. [0042] As described above, according to the present invention, the N pole and the S pole
The change in magnetic flux density at the boundary between
And the relative position of the boundary between the north pole and the south pole
Cogging torque is generated when the core passes through
Thus, the rotation of the motor can be stabilized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a DC brushless motor according to one embodiment of the present invention. FIG. 2 is an enlarged view showing a stator and a magnet in the DC brushless motor according to one embodiment of the present invention. FIG. 3 is a diagram for explaining a magnetization distribution of a magnet provided in a DC brushless motor according to one embodiment of the present invention. FIG. 4 is a diagram for explaining a magnetizing device for magnetizing a magnet provided in a DC brushless motor according to one embodiment of the present invention. FIG. 5 is a perspective view of a conventional brushless DC motor. FIG. 6 is a diagram for explaining a magnetization distribution of a magnet provided in a DC brushless motor as an example of the related art. FIG. 7 is a diagram for explaining a magnetizing device that magnetizes a magnet provided in a DC brushless motor as an example of the related art. [Description of Signs] 20 DC brushless motor 22 Stator 23 Rotor 24 Base 25 Stator yoke 26 Core throttle 27 Coil 28 Magnet 28A Magnet base material 29 Rotor output unit 30 Rotor base 31 Stator shaft 32 Bearing 33 Coil winding unit 40 Magnetizer 41 Magnetizing coil 42 Magnetizing yoke 43 Cylindrical base

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 5H002 AA01 AA09 AB06                 5H621 AA02 BB07 BB10 GA01 GA04                       HH01                 5H622 AA02 CA05 CA11 PP03 QB02                       QB09

Claims (1)

Claims: 1. A stator having a plurality of coil winding portions around which coils are wound, and a rotatably disposed face to face with the stator, the N pole being disposed in a circumferential direction. And a rotor made of permanent magnets having S poles alternately magnetized, wherein a maximum value and a minimum value of a magnetic flux density centered on a boundary position between the N pole and the S pole are provided. the interval is _{T 1,} when the Chaku磁周life of a set of N and S poles was _{T 0,} the ratio of the said interval _{T 1} wearing磁周period _{T 0 (T 1 / T 0} ) is 1 / A DC brushless motor, wherein the magnetization distribution of the permanent magnet is set to be 3 or more and less than 1/2.