JPH08223891A - Commutatorless motor - Google Patents

Abstract

PURPOSE: To reduce the sectional area and to smooth the rotation by disposing at least a pair of drive coils via a rotary shaft at the inside positions of a plurality of permanent magnets arranged on the circumference of a rotor at the shaft as a center, and disposing a yoke around the shaft between the coils of the pair. CONSTITUTION: A plurality of permanent magnets 13 are disposed on the circumference with the rotary shaft 12 of a rotor 10 as a center. On the other hand, a holder 22 is fixed to a board 21, an oilless bearing 24 for supporting the shaft 12 at the inside is fixed, a pair of bobbins 27 protrude from the outer surface of the holder 22 toward the inner peripheries of the magnets 13, and drive coils 28 are wound. A yoke 23 is disposed around the bearing 24 between the coils 28. Thus, the sectional area of a motor can be reduced, the magnetic flux density of a magnetic circuit is small at the outside part of the coils 28, and no abrupt magnetic change exists. Accordingly, no rotation irregularity occurs by cogging, and the rotation of the motor 10 can be smoothed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutatorless motor.

[0002]

2. Description of the Related Art Generally, a conventional non-commutator motor, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-54855, has a rotor in which a plurality of permanent magnets are alternately magnetized in opposite directions on a plane perpendicular to a rotation axis. , And the rotor is driven by a drive coil arranged in the non-rotating portion in the same direction as the rotating shaft. The yoke made of a magnetically conductive member is arranged at the center of the rotation shaft so as to largely surround the drive coil.

However, such a layout increases the cross-sectional area of the device, which may cause inconvenience depending on the purpose of use. Therefore, there is a rotor in which a permanent magnet of a rotor is arranged on a circumference around a rotation axis and a drive coil is arranged inside the permanent magnet so as to face the permanent magnet. The yoke is divided into two parts each having a half circumference, and is arranged inside the rotor so as to surround the periphery of the drive coil.

[0004]

As described above, the permanent magnets of the rotor are arranged on the circumference around the rotation axis, the drive coil is arranged inside the permanent magnet, and the circumference of the drive coil is surrounded. The arrangement of the yoke can reduce the cross-sectional area of the device.

However, with such a layout, when the relationship between the drive coil and the magnetic poles of the permanent magnets is switched with the rotation of the rotor, the change in the magnetic force sensitively affects the rotation of the rotor and affects the rotation of the rotor. Rotational unevenness called so-called cogging occurs in the axial direction, and a problem arises that resonance noise is generated from the frame to which the non-commutator motor is attached.

Therefore, an object of the present invention is to provide a non-commutator motor capable of reducing the cross-sectional area of the device and achieving smooth and quiet rotation.

[0007]

In order to achieve the above object, a commutatorless motor of the present invention comprises a rotor in which a plurality of permanent magnets are arranged around a rotary shaft with their magnetism alternately reversed. In a non-commutator motor which is driven by a change in magnetic flux generated by passing an alternating current to a drive coil arranged in a non-rotating portion to rotate the rotor, the rotor has a circle around the rotation axis. The plurality of permanent magnets are arranged, at least a pair of drive coils are arranged in the non-rotating portion at a position inside the permanent magnet with the rotation shaft interposed therebetween, and the rotation shaft is provided between the pair of drive coils. It is characterized by arranging a yoke around the.

With such a structure, the rotor is rotationally driven by the change in magnetic flux generated by passing an alternating current through the drive coil. Since the permanent magnets of the rotor are arranged on the circumference around the rotation axis and the drive coil is arranged inside the permanent magnet, the cross-sectional area of the device can be reduced.

Further, since the yoke is arranged inside the drive coil so as to surround the rotary shaft, the magnetic flux density of the magnetic circuit is small and a sudden magnetic change occurs at the portion on the outer end side where the drive coil faces the permanent magnet. Does not occur. Therefore, the rotor rotates smoothly without uneven rotation.

The yoke is divided into two in the circumferential direction, both yokes are arranged between the pair of drive coils, and the drive current applied to the drive coils is transmitted. It may be used as a conductive path for By doing so, the electrical wiring can be simplified and the device can be downsized.

Further, at least one of the both yokes is
A starting position determining portion for determining the rotation starting position of the rotor may be extendedly formed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view of a first embodiment in which the commutatorless motor of the present invention is used as an aspirator for measuring the temperature inside a vehicle compartment of an automobile, and FIG. 2 shows a rotor 10 of the commutatorless motor extracted upward. FIG. 3 is a front cross-sectional view of the state, FIG. 3 is a plan view of the state in which the rotor 10 is removed from the commutatorless motor, and FIG. 4 is an exploded perspective view. In addition, in FIG. 3, the permanent magnet 13 of the rotor 10 is illustrated by a broken line.

In the rotor 10, for example, about 4 to 10 blades are radially arranged, the fins 11 are arranged, the rotary shaft 12 is press-fitted in the central axis position of the fins 11, and the circumference of the rotary shaft 12 is the center. A plurality of (for example, six) permanent magnets 13 and the like arranged in the above are provided.

The inner and outer surfaces of the permanent magnet 13 are magnetic poles, and the permanent magnets 13 and the adjacent permanent magnets 13 are arranged so that their magnetism is alternately reversed. And surround the outer circumference of the permanent magnet 13,
A back yoke 14 made of iron for giving a magnetic flux to a Hall IC 29 described later is annularly arranged.

Reference numeral 21 denotes a substrate having a back surface provided with electric wiring, and a plastic holder 22 for rotatably supporting the rotor 10 is fixed to the front surface side of the substrate 21. Inside the central portion of the holder 22, the rotating shaft 12 of the rotor 10
The oil-impregnated bearing 24 for supporting the is fixed. Reference numeral 25 is a thrust receiver of the rotary shaft 12.

On a side surface of the holder 22, a pair of hobbins 27 are provided perpendicular to the rotary shaft 12 toward the inner peripheral surface of the permanent magnet 13.
Are projecting at 180 ° symmetrical positions (that is, on the same axis), and an electromagnetic coil (driving coil) 28 for rotationally driving the rotor 10 is wound around each hobbin 27.
Between the tip of the hobbin 27 and the inner peripheral surface of the permanent magnet 13,
A gap is formed.

In this way, the pair of drive coils 28 are arranged so as to face each other with the rotary shaft 12 interposed therebetween, and in such a layout, even if cogging occurs, the direction thereof is perpendicular to the axis.

On the back surface of the substrate 21 at the position where the permanent magnets 13 face each other, as shown in FIG. 3, the hole I is placed at a position rotated, for example, 30 ° with respect to the central axis of the drive coil 28.
C29 is fixed. The Hall IC 29 outputs a voltage signal that is substantially proportional to the strength of the magnetic flux received from the permanent magnet 13.

The alternating signal supplied to the drive coil 28 is controlled by the output signal from the Hall IC 29 in accordance with the rotational position of the permanent magnet 13. As a result,
The rotor 10 rotates at a predetermined speed.

The yoke 23 is shown by hatching in FIG. 3 so as to be easily understood, and the yoke 24 is surrounded by a pair of drive coils 28 on both sides of the rotary shaft 12 so as to surround the bearing 24. It is arranged around.

As described above, since the yoke 23 is disposed only inside the pair of drive coils 28, it contributes to the formation of the magnetic circuits of both drive coils 28 so as not to interfere with each other. The portion of the coil 28 facing the permanent magnet 13 on the tip end side does not contribute to the formation of the magnetic circuit.

Therefore, since the magnetic flux density of the magnetic circuit is small and no abrupt magnetic change does not occur in the portion of the drive coil 28 facing the permanent magnet 13, the magnetic flux density of the magnetic circuit does not occur, so that rotation unevenness due to the cogging phenomenon does not occur and the rotor does not rotate. 10 rotates smoothly.

The yoke 23 is formed integrally with the holder 22 by insert molding, and the lower end portion of the yoke 23 is pierced through the substrate 21 and fixed firmly. Further, as shown in FIG. 3, the yoke 23 is divided into two parts each having a half circumference and is formed so as not to come into contact with each other. The two yokes 23 are arranged between the two drive coils 28, respectively. , Is used as an electric path for supplying power to the coils of both drive coils 28.

Reference numeral 31 shown in FIG. 3 is an iron starter which is eccentric from the rotary shaft 12 and extends outward from both yokes 23 so as to determine the rotational start position of the rotor 10 and which is arranged on the surface of the substrate 21. It is a position determining yoke.

FIG. 5 shows a commutatorless motor according to a second embodiment of the present invention, in which the substrate 21 is arranged parallel to the direction of the rotary shaft 12, and the other portions are the same as those of the first embodiment. Is the same as the form. As described above, the setting of the mounting direction with respect to the substrate 21 may be arbitrary.

[0026]

According to the present invention, the permanent magnet of the rotor is arranged on the circumference around the rotation axis and the drive coil is arranged inside the permanent magnet, so that the cross-sectional area of the device can be made small. Moreover, since the yoke is arranged inside the drive coil so as to surround the rotary shaft, the magnetic flux density of the magnetic circuit is small at the outer end side of the drive coil facing the permanent magnet, and a sudden magnetic change occurs. Since there is no rotation unevenness due to cogging, the rotor rotates smoothly and quietly.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view of a commutatorless motor according to a first embodiment of the present invention.

FIG. 2 is a first view of the present invention in a state where a rotor is pulled out upward.
FIG. 3 is a front cross-sectional view of the commutatorless motor of the embodiment of FIG.

FIG. 3 is a plan view of the commutatorless motor according to the first embodiment of the present invention with the rotor removed.

FIG. 4 is an exploded perspective view of the commutatorless motor according to the first embodiment of the present invention.

FIG. 5 is an exploded perspective view of a commutatorless motor according to a second embodiment of the present invention.

[Explanation of symbols]

 10 rotor 12 rotating shaft 13 permanent magnet 23 yoke 28 drive coil

Claims (3)

[Claims] 1. A rotor in which a plurality of permanent magnets are alternately arranged so that their magnetisms are opposite to each other and is arranged around a rotary shaft is driven by a magnetic flux change generated by passing an alternating current through a drive coil arranged in a non-rotating portion. In the non-commutator motor configured to rotate by rotating the rotor, the plurality of permanent magnets are arranged on the circumference of the rotor around the rotation shaft, and the non-rotation part sandwiches the rotation shaft. And at least a pair of drive coils are arranged at a position inside the permanent magnet, and a yoke is arranged between the drive coils forming a pair so as to surround the rotary shaft and a yoke. 2. The yoke is divided into two in the circumferential direction, and both of the yokes are arranged between the pair of drive coils and a drive current applied to the drive coil. The non-commutator motor according to claim 1, which is used as a conductive path for transmitting electric power. 3. The non-commutator motor according to claim 2, wherein a starting position determining portion for determining a rotational starting position of the rotor is extendedly formed on at least one of the both yokes.