JPH08331822A - Dc brushless motor - Google Patents

Abstract

PURPOSE: To remarkably reduce the production of vibrations and noise from a thin DC brushless motor when the energization of the motor is switched without deteriorating the intinsic feature. CONSTITUTION: The production of vibrations and noise from a DC brushless motor is remarkably reduced by arranging paired stator assemblies on both sides of a rotor magnet 2 on a rotor assembly side in the direction of the axis of rotation and integrally coupling the stator yokes 4A and 4B of the stator assemblies to each other on their outer peripheral sections through supports 10 made of a soft resin or elastic rubber, forming reinforcing ribs to the yokes 4, or forming numerous semispheric dimples on the bottom faces of the yokes 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial type brushless DC motor used as a disk drive motor in OA equipment such as personal computers and word processors.

[0002]

2. Description of the Related Art FIG. 15 is a partially cutaway plan view showing the structure of a conventional three-phase axial type brushless DC motor, and FIG. 16 is a semi-longitudinal side view thereof. In each of these drawings, reference numeral 1 denotes a rotor yoke, a rotor magnet 2 is adhered to the lower surface of the rotor yoke, and a rotary shaft 3 is press-fitted and fixed in an orthogonal posture at a central portion of an axial center of the rotor yoke. The assembly is made up. Four
Is a stator yoke, which is fixed to a bearing housing 6 that rotatably supports the rotating shaft 3 via a radial bearing 5, and the upper surface of the stator yoke 4 faces the rotor magnet 2 in the rotating direction. A plurality of amateur coils 7 are adhered to each other, and the plurality of amateur coils 7 are electrically connected by a copper foil pattern (not shown) formed on the stator yoke 4. Three Hall elements 8 for detecting the magnetic position of the rotor magnet 2 are fixed, and a stator assembly is constituted by the above components.

In a three-phase axial type brushless DC motor having the rotor assembly and the stator assembly as a basic structure, the outer shape of each armature coil 7 on the stator assembly side is as shown in FIG. In order to effectively generate the radiation, the shape is formed with a line segment parallel to or close to the radiation x from the rotation center o. The vertical cross-sectional shape of the amateur coil 7 is as shown in FIG.
The number of turns in the height direction of a is formed to be uniform over the inner and outer circumferences. Further, the magnetization distribution of the rotor magnet 2 on the rotor assembly side is N as shown in FIG.
A magnetization boundary line L between the pole portion 2n and the S pole portion 2s is formed along the radiation x from the rotation center o.

In the conventional brushless DC motor having the above-mentioned structure, the signal from the hall element 8 is sent to the drive circuit (not shown) so that each of the amateur coils 7 can be operated.
By sequentially energizing the rotor assembly, a rotational force is generated based on Fleming's left-hand rule, and the rotor assembly is rotationally driven.

FIGS. 19 and 20 are a partially cutaway plan view and a semi-longitudinal side view showing a structure of a conventional twin rotor type brushless DC motor. An amateur coil is mounted on a non-magnetic printed circuit board 9. A pair of rotor assemblies are arranged on both sides in the direction of the rotation axis of the stator assembly formed by bonding 7 so that the polarities of the rotary magnets 2A and 2B bonded to the rotor yokes 1A and 1B are opposite to each other. Since the other configurations are the same as those of the single rotor type brushless DC motor shown in FIGS. 15 to 16, the corresponding parts are designated by the same reference numerals and detailed description thereof will be omitted. .

[0006]

The conventional brushless DC motor having the above-mentioned structure has a problem that large noise and vibration are generated for various reasons as listed below. (1) Exciting force in the thrust direction (vertical direction in the figure) or the radial direction is generated in the rotor magnet 2 with the energization of the amateur coil 7, and the exciting force causes the rotor assembly to vibrate and generate noise. (2) Since the stator yoke 4 has a flat plate shape and only the inner peripheral portion thereof is fixed, the bending and torsional rigidity of the stator yoke 4 is insufficient, and noise is amplified by resonance with the exciting force. To be done. (3) When the magnetic flux distribution between the rotor magnet 2 and the stator yoke 4 is viewed, the magnetic flux density in the circumferential direction is uniform as shown in FIG. When there is a switch, the armature coil 7 undergoes a sudden torque change, and due to the large torque ripple, a large impact force acts on the rotor yoke 1 and the rotor assembly, generating vibration and noise.

Further, in the conventional twin rotor type brushless DC motor shown in FIGS. 19 and 20, the length L of the redundant portion which does not contribute to the generation of the rotational torque in the amateur coil 7 is large, and the redundant portion rotates. Unnecessary vectors other than directions were generated, which contributed to vibration and noise.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a brushless DC motor capable of significantly reducing the generation of vibration and noise without losing the original characteristics of the thin type. I am trying.

[0009]

In order to achieve the above object, a brushless DC motor according to the invention of claim 1 is a rotor in which a rotor magnet is bonded to a rotor yoke having a rotating shaft fixed to the central portion of the shaft center. An assembly, a stator assembly in which a plurality of armature coils facing the rotor magnet are bonded in the rotational direction to a stator yoke fixed to a bearing housing that rotatably supports the rotating shaft, and the armature coil is sequentially energized. In the brushless DC motor including a drive circuit for rotationally driving the rotor assembly, a pair of stator assemblies are arranged on both sides of the rotor magnet on the rotor assembly side in the rotation axis direction.

In the brushless DC motor having the above-mentioned structure, it is preferable that the stator yokes of the pair of stator assemblies are integrally connected to each other at their outer peripheral portions via columns, and the columns are made of flexible resin or elastic rubber. Is preferably provided.

A brushless DC motor according to a fourth aspect of the present invention is one in which a reinforcing rib is formed on a stator yoke on the side of the stator assembly, and a brushless DC motor according to the invention of the fifth aspect is of a stator yoke on the side of the stator assembly. A large number of hemispherical dimples are formed on the bottom surface.

In the brushless DC motor according to each of the above claims, the armature coil is wound such that the number of turns of the coil wire in the height direction is gradually increased from the outer circumference to the inner circumference, or the amateur coil is wound. It is desirable that the outer shape of the rotor is formed into a circular shape, or that the magnetizing boundary line of the rotor magnet on the rotor assembly side is not parallel to the radiation from the rotation center.

According to a seventh aspect of the present invention, in the brushless DC motor, all the magnetization boundary lines of the rotor magnet are straddled between the facing surfaces of the rotor magnet on the rotor assembly side and the stator yoke on the stator assembly side. It is provided with a magnetic short plate.

Here, it is preferable that the magnetic short plates are integrally connected at their inner peripheral portions.

Further, in the brushless DC motor according to the invention of claim 11, a pair of rotor magnets are adhered to rotor yokes each having a rotating shaft fixed to the central portion of the shaft center and spaced apart in the axial direction. Rotor assembly, and a plurality of armature coils facing the pair of rotor magnets are arranged in the rotation direction on a stator yoke fixed to a bearing housing that is arranged between the pair of rotor assemblies and rotatably supports the rotating shaft. In a brushless DC motor including a stator assembly that is installed, and a drive circuit that sequentially energizes the amateur coil to rotationally drive the rotor assembly,
The armature coil on the side of the stator assembly is formed by winding a circular arc-shaped iron core from the inner circumference to the outer circumference, and the polarities of a pair of rotor magnets facing each other with the armature coil in between are formed to have the same polarity. It has been done.

[0016]

According to the first aspect of the present invention, the thrust force acting on the rotor magnet on the rotor assembly side due to the energization of the armature coil on the stator assembly side is canceled by the pair of stator assemblies. Vibrations of the rotor assembly and accompanying noise are reduced. In particular, since the pair of stator yokes are integrally connected via the columns, the bending / torsion rigidity of the stator yoke is improved, and the amplification of vibration and noise due to resonance with the energization switching frequency is avoided. Further, when the support column is made of flexible resin or elastic rubber, it is possible to absorb and damp the vibration of the stator yoke and suppress the generation of vibration and noise.

According to the fourth aspect of the present invention, the rigidity of the stator yoke is improved without increasing the plate thickness, and amplification of vibration and noise due to resonance with the exciting force in the thrust direction and the radial direction is suppressed. Further, according to the invention of claim 5, even if the stator yoke vibrates, the sounds emitted from the large number of hemispherical dimples formed on the bottom surface thereof interfere with each other and cancel each other out. for,
It is possible to reduce noise.

Further, in the invention of each of the above claims, the amateur coil is wound so that the number of turns in the height direction is gradually increased from the outer circumference to the inner circumference, or the outer shape of the amateur coil is circular. By forming the magnetizing boundary line of the rotor magnet on the side of the rotor assembly not parallel to the radiation from the center of rotation, the torque change at the time of switching the energized phase becomes gentle, and the rotor assembly The impact force that acts can be mitigated, and the generation of vibration and noise can be reduced.

According to the ninth aspect of the invention, due to the presence of the magnetic short plate disposed between the facing surfaces of the rotor magnet and the stator yoke, the magnetic flux distribution between the rotor magnet and the stator yoke is circumferentially increased. Since the magnetic flux density of is coarse near the magnetization boundary line, the torque change at the time of switching the energization phase becomes gentle, the impact force acting on the rotor assembly at the time of switching the energization is alleviated, and vibration and noise are reduced. Is possible. here,
Particularly, when the magnetic short plates are integrally connected at their inner peripheral portions, the workability of manufacturing the magnetic short plates and the assemblability of the entire motor are improved.

Further, according to the invention of claim 11, since the length of the redundant portion which does not contribute to the generation of the rotating torque by the amateur coil in the so-called twin rotor type brushless DC motor is shortened, the redundant portion is generated. Unnecessary vectors other than the rotation direction, which are one of the factors that generate vibration and noise, are significantly reduced, which makes it possible to reduce vibration and noise.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 and FIG. 2 are a partially cutaway plan view and a semi-longitudinal side view showing a configuration of a brushless DC motor of a three-phase axial type, respectively, in a rotational axis direction of a rotor magnet 2 on a rotor assembly side. The armature coils 7A and 7B in which a pair of stator assemblies are bonded to both sides of the stator yokes 4A and 4B of the pair of stator assemblies are provided with the rotor magnets 2.
In which the stator yokes 4A and 4B of the stator assembly are integrally joined at a plurality of locations on their outer peripheral portions via columns 10 made of flexible resin or elastic rubber. Is. Since the other components are the same as those of the conventional example shown in FIGS. 15 and 16, the same reference numerals are given to the corresponding portions, and the description thereof will be omitted.

In the three-phase axial type brushless DC motor having the above structure, a pair of thrust-direction forces acting on the rotor magnet 2 on the rotor assembly side as the armature coils 7A, 7B on both stator assembly sides are energized. This is offset by the stator assembly, and the vibration of the rotor assembly and the accompanying noise are reduced. Further, since the pair of stator yokes 4A and 4B are integrally coupled via the support column 10, the bending and torsional rigidity of the stator yokes 4A and 4B are improved, and the vibration and noise due to resonance with the energization switching frequency are amplified. Is avoided, and the support pole 10 made of flexible resin or elastic rubber prevents the stator yoke 4
It is possible to suppress the vibration and noise by absorbing and damping the vibrations of A and 4B.

Embodiment 2 As shown in FIG. 3, a stator assembly provided only on the lower side of the rotor assembly is pressed at a plurality of locations including a location corresponding to the axial center hole of the armature coil 7 of the stator yoke 4. The reinforcing ribs 4a are formed by working. In the case of this embodiment, the bending of the stator yoke 4 is prevented without increasing the plate thickness of the stator yoke 4 and the thickness of the entire motor.
It is possible to improve the torsional rigidity and suppress amplification of vibration and noise due to resonance with the exciting force in the thrust direction and the radial direction.

Example 3: As shown in FIGS. 4 and 5,
A large number of hemispherical dimples 4b are formed on the bottom surface of the stator yoke 4 in the stator assembly arranged only on the lower side of the rotor assembly. According to this embodiment, even if the stator yoke 4 vibrates, The sounds emitted from the large number of dimples 4b interfere with each other and cancel each other, so that the noise can be reduced.

Embodiment 4 As shown in FIG. 6, the armature coil 7 on the stator assembly side has its height direction h.
Is wound so that the number of turns of the coil wire 7a gradually increases from the outer circumference to the inner circumference.
In the case of this embodiment, the torque generated in the armature coil 7 at the time of switching the energized phase is moderately increased. Therefore, the impact force acting on the rotor assembly at the time of switching the energized phase is alleviated, and the vibration and noise are reduced. Can be reduced.

Embodiment 5: As shown in FIG. 7, the outer shape of the armature coil 7 on the stator assembly side is formed into a circular shape. In the case of this embodiment, the coil wire 7a which contributes to the generation of torque is formed. Since the effective length gradually increases, the torque generated in the armature coil 7 at the time of switching the energized phase moderately increases, so that the impact force acting on the rotor assembly at the time of switching the energized phase is reduced. Therefore, it is possible to reduce vibration and noise.

Embodiment 6 As shown in FIG. 8 or 9, in the magnetization distribution of the rotor magnet 2 on the rotor assembly side, the magnetization boundary line L between the N pole portion 2n and the S pole portion 2s is the rotation center o. In this embodiment, when the energized phase is switched with the rotation of the rotor magnet 2,
Since the magnetic field to the coil wire 7a of the armature coil 7 is gradually changed, the torque change at the time of switching the energized phases is gentle, the impact force acting on the rotor assembly is alleviated, and the vibration and noise are reduced. Is possible.

Embodiment 7: As shown in FIGS. 10 and 11, on the surface of the rotor magnet 2 on the rotor assembly side facing the stator yoke 4, the N pole portion 2n and the S pole portion 2s of the rotor magnet 2 are formed. Radial magnetic short plates 11 are arranged in a state of straddling all the magnetization boundary lines L, and these magnetic short plates 11 are integrally connected via a ring body 12 at their inner peripheral portions. In the case of this embodiment, as shown in FIG. 12, the magnetic flux density in the circumferential direction becomes rough in the vicinity of the magnetization boundary line L, and the torque change at the time of switching the energized phase becomes gentle. The impact force acting on the rotor assembly at the time of switching the energized phases is alleviated, and it is possible to reduce vibration and noise. Also, each magnetic short plate 11
Are integrally connected via the ring body 12, so that the magnetic short plate 10 can be easily manufactured and the motor as a whole can be assembled.

Embodiment 8: FIG. 13 and FIG. 14 are a partially cutaway plan view and a semi-longitudinal side view showing the structure of a three-phase axial type twin rotor type brushless DC motor, respectively. 19 and FIG.
The same components as those of the conventional twin rotor type brushless DC motor shown in FIG. 2 are assigned the same reference numerals and explanations thereof are omitted. Further, in this embodiment, the amateur coil 7 on the stator assembly side is provided.
Is formed by winding a circular arc-shaped iron core 13 from the inner circumference to the outer circumference, and a pair of rotor magnets 2A and 2B facing each other with the armature coil 7 in between.
Is formed to have the same polarity, and in the case of this embodiment, the length of the redundant portion that does not contribute to the generation of the rotational torque is as short as l in FIG. Unnecessary vectors other than the direction of rotation generated in 1 are extremely reduced, and vibration and noise can be reduced accordingly.

[0030]

As described above, according to the inventions of claims 1 to 3, the thrust force acting on the rotor magnet on the rotor assembly side upon energization is offset by the pair of stator assemblies, so that the rotor assembly is compensated. It is possible to reduce the vibration and noise accompanying it. Particularly, by integrally connecting the pair of stator yokes via the support columns, the bending and torsional rigidity of the stator yokes can be improved, and the amplification of vibration and noise due to resonance with the energization switching frequency can be avoided. By using the support column made of flexible resin or elastic rubber, it is possible to absorb and damp the vibration of the stator yoke, and further suppress the generation of vibration and noise.

According to the fourth aspect of the present invention, the rigidity of the stator yoke is improved without increasing the plate thickness of the stator yoke and the thickness of the entire motor, and without losing the original thin features of the brushless DC motor. Amplification of vibration and noise due to resonance with the vibration force in the thrust direction and the radial direction can be suppressed. Further, according to the invention of claim 5, even if the stator yoke vibrates, the noises emitted from the large number of hemispherical dimples formed on the bottom surface of the stator yoke interfere with each other and cancel each other out, thereby reducing the noise. can do.

Further, in the invention of each of the above claims, the amateur coil is wound so that the number of turns of the coil wire in the height direction is gradually increased from the outer circumference to the inner circumference, or the outer shape of the amateur coil is formed. By forming a circle, or by configuring the magnetization boundary line of the rotor magnet on the rotor assembly side to be non-parallel to the radiation from the center of rotation, the torque change at the time of switching the energized phase is moderated, It is possible to reduce the impact force acting on the rotor assembly and reduce the generation of vibration and noise.

Further, according to the invention of claim 9, in the magnetic flux distribution between the rotor magnet and the stator yoke, the magnetic short-circuit plate is provided between the facing surfaces of the rotor magnet and the stator yoke, in the circumferential direction. It is possible to roughen the magnetic flux density near the magnetizing boundary line.This makes it possible to moderate the torque change during switching of the energized phase, reduce the impact force that acts on the rotor assembly during energization switching, and reduce vibration and noise. Occurrence can be reduced. Here, in particular, by integrally connecting the magnetic short plates at their inner peripheral portions, the manufacturing workability of the magnetic short plates and the assembling property of the entire motor can be made easy and good.

Further, according to the invention of claim 11, it is possible to shorten the length of the redundant portion which does not contribute to the generation of the rotating torque by the amateur coil in the so-called twin rotor type brushless DC motor, and in the redundant portion. Unnecessary vectors other than the direction of rotation, which is one of the factors that generate vibration and noise, are greatly reduced.
It is possible to further reduce noise.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing the structure of a three-phase axial type brushless DC motor according to a first embodiment of the present invention.

FIG. 2 is a semi-longitudinal side view of FIG.

FIG. 3 is a semi-longitudinal side view showing a configuration of a three-phase axial type brushless DC motor according to a second embodiment of the present invention.

FIG. 4 is a semi-longitudinal side view showing the configuration of a three-phase axial type brushless DC motor according to a third embodiment of the present invention.

5 is a bottom view of the main part of FIG. 4. FIG.

FIG. 6 is an enlarged vertical sectional view of an amateur coil of a brushless DC motor of a three-phase axial type according to Embodiment 4 of the present invention.

FIG. 7 is a plan view of a main part of a three-phase axial type brushless DC motor according to a fifth embodiment of the present invention.

FIG. 8 is a plan view showing an example of a magnetization distribution of a rotor magnet in a three-phase axial type brushless DC motor according to a sixth embodiment of the present invention.

FIG. 9 is a plan view showing another example of the magnetization distribution of the rotor magnet in the three-phase axial type brushless DC motor according to the sixth embodiment of the present invention.

FIG. 10 is a plan view of a rotor magnet in a three-phase axial type brushless DC motor according to a seventh embodiment of the present invention.

11 is a side view of FIG.

FIG. 12 is an enlarged side view of essential parts showing a magnetic flux distribution in a three-phase axial type brushless DC motor according to a seventh embodiment of the present invention.

FIG. 13 is a partially cutaway plan view showing the structure of a three-phase axial type twin rotor type brushless DC motor according to an eighth embodiment of the present invention.

FIG. 14 is a semi-longitudinal side view of FIG.

FIG. 15 is a partially cutaway plan view showing a configuration of a conventional three-phase axial type brushless DC motor.

16 is a semi-longitudinal side view of FIG.

FIG. 17 is an enlarged vertical cross-sectional view of an amateur coil of a conventional three-phase axial type brushless DC motor.

FIG. 18 is a plan view showing a magnetization distribution of a rotor magnet in a conventional three-phase axial type brushless DC motor.

FIG. 19 is a partially cutaway plan view showing a configuration of a conventional three-phase axial type twin rotor type brushless DC motor.

20 is a semi-longitudinal side view of FIG.

FIG. 21 is an enlarged side view of a main part showing a magnetic flux distribution in a conventional three-phase axial type brushless DC motor.

[Explanation of symbols]

 1 rotor yoke 2 rotor magnet 3 rotating shaft 4, 4A, 4B stator yoke 4a reinforcing rib 4b dimple 6 bearing housing 7, 7A, 7B amateur coil 7a coil wire 10 strut 11 magnetic short plate L magnetic boundary line

Front page continued (72) Inventor Masakazu Kido 2075 Umiyoshi, Okayama, Okayama Prefecture Omron Okayama Co., Ltd.

Claims (11)

[Claims] 1. A rotor assembly in which a rotor magnet is adhered to a rotor yoke having a rotating shaft fixed to a central portion of an axial center, and a rotor yoke fixed to a bearing housing which rotatably supports the rotating shaft. A plurality of armature coils facing each other in a rotating direction are bonded together in a rotation direction, and a drive circuit for rotating the rotor assembly by sequentially energizing the armature coils, the brushless DC motor having the rotor assembly side. Brushless DC motor, wherein a pair of stator assemblies are arranged on both sides of the rotor magnet in the rotation axis direction. 2. The brushless DC motor according to claim 1, wherein the stator yokes of the pair of stator assemblies are integrally connected to each other at their outer peripheral portions via columns. 3. The brushless DC motor according to claim 2, wherein the support column is made of flexible resin or elastic rubber. 4. A rotor assembly in which a rotor magnet is bonded to a rotor yoke having a rotating shaft fixed to the center of the shaft center, and a rotor yoke fixed to a bearing housing which rotatably supports the rotating shaft. A plurality of armature coils facing each other in the direction of rotation are bonded together, and a drive circuit for rotating the rotor assembly by sequentially energizing the armature coils. Brushless DC motor characterized in that reinforcing ribs are formed on the stator yoke of the above. 5. A rotor assembly in which a rotor magnet is adhered to a rotor yoke having a rotating shaft fixed to a central portion of an axial center, and a rotor yoke fixed to a bearing housing which rotatably supports the rotating shaft. A plurality of armature coils facing each other in the direction of rotation are bonded together, and a drive circuit for rotating the rotor assembly by sequentially energizing the armature coils. A brushless DC motor, characterized in that a large number of hemispherical dimples are formed on the bottom surface of the stator yoke. 6. The armature coil is wound so as to gradually increase the number of turns of the coil wire in the height direction from the outer circumference to the inner circumference.
The brushless DC motor according to any one of 1. 7. The brushless DC motor according to claim 1, wherein the outer shape of the amateur coil is circular. 8. The brushless DC motor according to claim 1, wherein a magnetizing boundary line of the rotor magnet on the rotor assembly side is configured to be non-parallel to the radiation from the center of rotation. 9. A rotor assembly in which a rotor magnet is bonded to a rotor yoke having a rotating shaft fixed to the center of the shaft center, and a rotor yoke fixed to a bearing housing which rotatably supports the rotating shaft. A plurality of armature coils facing each other in a rotating direction are bonded together in a rotation direction, and a drive circuit for rotating the rotor assembly by sequentially energizing the armature coils, the brushless DC motor having the rotor assembly side. 2. A brushless DC motor, characterized in that a magnetic short plate is arranged between the facing surfaces of the rotor magnet and the stator yoke on the side of the stator assembly so as to straddle all the magnetization boundaries of the rotor magnet. 10. The brushless DC motor according to claim 9, wherein the magnetic short plates arranged in a state of straddling all the magnetized boundary lines of the rotor magnet are integrally connected at their inner peripheral portions. 11. A pair of rotor assemblies each having a rotor magnet fixed to a central portion of the shaft center and having rotor magnets bonded to rotor yokes arranged at intervals in the axial direction, and between the pair of rotor assemblies. A stator assembly, in which a plurality of armature coils facing the pair of rotor magnets are disposed in a rotating direction on a stator yoke fixed to a bearing housing that rotatably supports the rotation shaft, and the armature coil. In a brushless DC motor including a drive circuit that sequentially energizes to drive the rotor assembly to rotate, an armature coil on the stator assembly side is formed by winding a circular arc-shaped iron core from an inner circumference to an outer circumference. And a pair of rotors facing each other with the amateur coil in between. Brushless DC motor, wherein a polarity of the net is formed on the same pole.