JP2002291214A - Flat motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat brushless motor in which the inertia of a rotor is not large. SOLUTION: The flat brushless motor comprises a rotating shaft 10 supported on a housing 20 and forming the rotor 2, permanet magnets 12 arranged in the radial direction and rotating integrally with the rotating shaft 10, a plurality of coils 3 arranged on the outer diameter of the permanent magnets 12 in the circumferential direction, first yokes 4 supporting one side of the coils 3 on the axial side to form stators 7 and changing the direction of magnetic flux coming from the permanent magnets 12 from radialy to axially, and second yokes 5 arranged on the other side of the coils 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flat motor, and is used, for example, as a flat brushless motor.

[0002]

2. Description of the Related Art Conventionally, a flat brushless motor that is flat in the axial direction is known, for example, from Japanese Patent Application Laid-Open No. 2000-37106. In the motor disclosed in this publication, as shown in FIG. 5, a cylindrical sleeve portion is fitted and fixed to a disk-shaped base made of a non-magnetic metal material, and a bearing is fixed inside the cylindrical sleeve portion. . A flat ring-shaped yoke is provided on the disc-shaped base, and a plurality of air-core coils are fixedly arranged on the disc-shaped base with an insulating plate interposed therebetween. The rotor facing the stator includes a disk-shaped holder, a flat ring-shaped permanent magnet fixed to one surface of the rotor, and a motor shaft fitted and fixed to the holder. The permanent magnet is a multi-pole permanent magnet that is magnetized in the axial direction so that the N pole and the S pole are alternately located. The motor shaft integrated with the holder is rotatably supported by fitting to the bearing of the stator. You.

[0003]

However, in the motor disclosed in the above-mentioned publication, an insulator is interposed on a disc-shaped base, and an air-core coil is disposed on the insulator in the circumferential direction. In this configuration, a permanent magnet that rotates together with the motor shaft is disposed in the axial direction.

[0004] For this reason, since the permanent magnet is provided to face the air-core coil provided in the circumferential direction, the size in the axial direction becomes large. Generally, the inertia I of the rotor is the fourth power of the rotor density ρ and the rotor radius r and a constant K
, The inertia of the rotor increases as the rotation radius of the rotor increases. When the inertia of the rotor becomes large, when the rotor starts to rotate, an inertia moment acts on the rotor to keep rotating, so that even if a motor stop command is issued to the motor, the rotation cannot be stopped immediately. That is, this detects the entrapment between the fixed member and the movable member movable with respect to the fixed member (for example, in a vehicle, entrapment by a wind regulator, a sunroof, or the like), and immediately when the entrapment occurs, the motor When used as a motor that stops rotating and rotates the motor in the reverse direction, such a motor with large inertia cannot be used.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a flat brushless motor in which inertia of a rotor does not increase.

[0006]

The first technical means taken to solve the above-mentioned problems is that a base member, a rotor rotatably supported on the base member, and a rotor outer peripheral surface are provided. A permanent magnet that is fixed and magnetized in the radial direction of the rotor, a stator that is disposed on the outer peripheral side of the permanent magnet on the base member, and that is disposed on the stator in a circumferential direction of the rotor. That is, a flat motor is constituted by a plurality of coils.

A second technical means is that the stator is disposed on one side in the axial direction of the coil, and converts the magnetic flux generated by the magnet from a radial direction to an axial direction with respect to the coil. And a second yoke disposed on the other side in the axial direction of the coil. According to this means, the permanent magnet that rotates integrally with the rotor becomes smaller than the first yoke, so that the radial magnetic flux from the permanent magnet can be converted in the axial direction and transmitted from the first yoke to the second yoke. Become. Therefore, since the rotor diameter can be made smaller than the plurality of coils supported by the first yoke arranged in the circumferential direction, the inertia of the rotor does not increase, and a flat brushless motor with a reduced moment of inertia of the rotor is provided.

Further, as a third technical means, the coil is an air-core coil, the first yoke has a coil supporting portion for supporting the coil, and the coil supporting portion transfers the magnetic flux in the axial direction of the coil to the second yoke. Is transmitted, the magnetic flux of the magnetic field in the axial direction of the coil can be efficiently transmitted to the second yoke by the coil supporting portion of the first yoke and increased. Therefore, a highly efficient flat brushless motor is provided.

Further, as a fourth technical means, when the first yoke has a thick part and a thin part in the axial direction, and the coil is disposed on the thin part, the first yoke has a thick part in the axial direction. If the thickness is made substantially the same, it is possible to provide a flat brushless motor whose thickness is reduced in the axial direction.

Further, as a fifth technical means, if the second yoke is formed in a flat disk shape, the size in the axial direction does not increase even if the second yoke is arranged to face the coil.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing a configuration of a flat brushless motor (hereinafter, referred to as a motor) 1 according to a first embodiment. The motor 1 includes a rotor 2 having a rotating shaft 10 disposed on the inner diameter of the yoke 4 via a bearing 11 with respect to a stator 7 having a yoke 4, a coil 3, and a back yoke 6 disposed in a housing. However, the stator 7 is configured to be rotatable by applying a known connection method of Δ connection or Y connection to each of the coils 3 arranged in the circumferential direction and energizing each coil 3. On the other hand, the rotor 2 can rotate.

Referring to FIG. 1, the structure of the motor 1 will be described. The housing 20 is made of a bottomed cylindrical metal material and has a boss 20a at the center. On a boss 20a provided at the center of the motor, a rotating shaft 10 serving as the rotor 2 is rotatably disposed via a bearing 11 having a bearing shape. The rotating shaft 10 is made of a metal material, and the lower side shown in FIG. 1 has a disk-shaped base portion 10a. The N-pole, S-pole, N-pole, and S-pole (four poles) are alternately repeated on the outer periphery of the base 10a of the rotating shaft 10 at intervals of 90 degrees in the circumferential direction.
An annular permanent magnet 12 magnetized in the radial direction so that the magnetic flux is generated in the radial direction is fixed by strong fixing means such as an adhesive. In the present embodiment, the above-described annular permanent magnet 12 is used on the outer periphery of the base portion 10a.
The base part 10 is divided into poles and S poles.
A different fixing means may be used on the outer periphery of a to rotate integrally with the rotor 2.

FIG. 2 is a view showing the structure of the coils 3 and the yokes 4 and 6 arranged outside (outer diameter) of the outer periphery of the annular permanent magnet 12. The six coils 3 are arranged in the circumferential direction in opposition to one annular thin flat disk-shaped back yoke 6 made of a magnetic material such as an iron plate. The coil 3 has an inner peripheral surface 3a and an outer peripheral surface 3b in the radial direction, the outer peripheral surface 3b has the same arc shape as the outer shape of the back yoke 6, and the outer shape has an arc shape and a substantially trapezoidal cross section. A copper wire is wound around a bobbin 5 made of a nylon-based resin. The copper wire is wound around the winding portion of the bobbin 5, and a void 13 is formed in the center of the coil 3 by the bobbin 5. The coils 3 wound around the bobbins 5, respectively, are arranged concentrically with respect to the center of the disk of the back yoke 6 in the circumferential direction.

The yoke 4 made of a magnetic material such as iron has a substantially trapezoidal shape having an arc on the outer periphery similar to the outer shape of the coil 3 so as to cover one side of the coil 3 in the axial direction. Further, the yoke 4 protrudes toward the coil side and has a protruding portion (a coil supporting portion) 4a fitted into the gap 13 of the coil 3 and a bent portion 4c facing the inner peripheral surface 3a of the coil 3;
The yoke 4 extends at a right angle in the axial direction from a bottom surface 4b that contacts the inner wall of the housing 20. Such a yoke 4 is provided for each of the six coils 3 arranged side by side in the circumferential direction.

In a state of being assembled to the housing 20, an annular permanent magnet 12 is fixed to a base portion 10a of the rotating shaft 10 disposed on the housing 20 via a bearing 11. In a state where the yoke 4 shown in FIG. 2 has the protruding portion 4a and the bent portion 4a protruding upward in the axial direction on the inner wall of the housing 20, the yoke 4 is separated from the annular permanent magnet 12 by a predetermined distance in the radial direction. 4 are arranged in the circumferential direction. The coil 3 wound around the bobbin 5 is arranged for each protruding portion 4a of the yoke 4 arranged in the circumferential direction.
The coil 3 is arranged so that the projection 4a fits into the coil 3. With the coil 3 fitted in the protruding portion 4a of the yoke 4, a disk-shaped back yoke 6 made of a flat plate made of a material such as iron is placed on the opposite surface of the coil 3 in the axial direction from the axial direction. An axial space is formed by the protruding portion 4a, and the convex portion 6a of the back yoke 6 is positioned and fitted in this axial space at several places. Since the coil 3 is disposed on the yoke 4 and the axial movement of the coil 3 is regulated by the back yoke, the housing 20, the yoke 4 and the back yoke 6 are both provided in the gap 13.
Is fixed by a bolt 9 inserted from the back yoke side and a nut 8 screwed to the bolt 9.

The flow of the magnetic flux in the assembled state shown in FIG. 1 will be described as an example. The magnetic flux from the permanent magnet 12 magnetized in the radial direction is received by the bent portion 4c of the yoke 4 and transmitted to the bottom surface. In the figure, the direction of the magnetic flux is radial. The protrusion 4 a is fitted into the gap 13 of the coil 3, and the direction of the magnetic flux is changed to the axial direction by the protrusion 4 a so as to escape to the back yoke 6. Then, the magnetic flux is applied to the back yoke 6
At the position where two or one adjacent coils 3 arranged in the circumferential direction are skipped based on the position where the coil has escaped from the rear yoke 6, and the projecting portion of the yoke 4 b from the back yoke 6. 4a, the bottom surface 4b, and the bent portion 4a, and finally return to the permanent magnet 12. Therefore, by energizing the coil 3 and sequentially performing such a change in the magnetic flux in the circumferential direction, an electromagnetic force acts between the coil 3 and the permanent magnet 12, and the rotor 2 rotates with respect to the stator 7. Can be done.

Therefore, with the above configuration, the rotating shaft 10
The yoke 4, the coil 3, and the back yoke 6 are configured to have an outer diameter with respect to the permanent magnet 12 so as to convert the magnetic flux from the permanent magnet 12 fixed to the shaft from the radial direction to the axial direction. The brushless motor 1 can be realized. In this case, the rotor 2 is disposed inside the yoke 4 that supports the coil 3 and the rotor diameter is reduced, so that the inertia of the rotor 2 can be reduced. Therefore, the motor can be started and stopped reliably.

(Second Embodiment) FIGS. 3 and 4 show the configuration of a second embodiment. The configuration of the second embodiment is basically the same as that of the first embodiment, but differs in the shape of the yoke 4, the shape of the bobbin 5, and the structure for supporting the coil 3 wound on the bobbin 5. Therefore, the details will be described below.

Housing 20 made of cylindrical metal with a bottom
, A bearing 11 is provided on a central boss portion 20a, and a rotating shaft 10 serving as a rotor 2 made of a metal material is disposed in a rotatable state via the bearing 11 provided on the boss portion 20a. The rotating shaft 10 has a base portion 10a in the same form as in the first embodiment, and an annular permanent magnet 12 magnetized in the radial direction is provided.

In the second embodiment, a yoke 4 made of a sintered metal is disposed on a housing so as to face a permanent magnet 12 at a predetermined interval in a radial direction. A plurality (six) of the yokes 4 shown in FIG. 3 are arranged in the circumferential direction. That is, when the yoke 4 is disposed in the circumferential direction, the yoke 4 has an arc-shaped inner peripheral surface 4h concentric with the center of the boss portion 20a of the housing 20, and has a thick portion 4 in the axial direction.
e, a thin portion 4f and a coil support portion 4g.
The thick part 4e exists on the inner diameter side, and as it goes to its outer diameter,
There is a thin portion 4f and a coil support 4g. Thick part 4e
And the thin portion 4f is tapered in the radial direction. The coil 3 wound around the bobbin 5 having a U-shaped cross section in the axial direction is mounted on the coil supporting portion 4g. When the coil 3 is mounted on the coil supporting portion 4g, one axial end surface 5a of the bobbin 3 is in contact with the thin portion 4f on the inner diameter side of the coil supporting portion 4g and the other end surface 5b.
Is covered with a disk-shaped back yoke 6. The convex portion 6 a provided on the back yoke 6 positions the back yoke 6 at a predetermined position on the yoke 4. In a state where the back yoke 6 covers the bobbin around which the coil 3 is wound, a gap 13 is formed in the coil 3.
In the position where is provided, the yoke 4, the coil 3, and the back yoke 6 are all restricted from moving in the axial direction by the bolt 9 and the nut 8 screwed to the bolt 9. In this case, when the bobbin 5 around which the coil 3 is wound is provided on the thin portion 4f of the yoke 4, the thickness of the thick portion 4e is substantially the same in the axial direction. Thus, even if the coil 3 is disposed on the yoke, the coil 3 does not increase in the axial direction. In addition, the coil supporting portion 4g fits into the gap 13 of the coil 3 wound around the bobbin 5, and can reliably support the bobbin 5 around which the coil 3 is wound so as not to move in the circumferential direction and the radial direction.
Since the magnetic flux can be made to pass through the entire inside of the coil supporting portion fitted in 3, the density of the magnetic flux passing through the inside of the coil can be increased.

Next, the flow of magnetic flux in the second embodiment will be described. Magnetic flux from the permanent magnet 12 magnetized in the radial direction is received by the inner peripheral surface 4 h of the yoke 4, and the thick portion 4 e and the thin portion 4 are received.
f, where the direction of the magnetic flux is the radial direction. In addition, since the coil supporting portion 4 g is fitted in the gap 13 of the coil 3, the direction of the magnetic flux is changed in the axial direction by the coil supporting portion 4 g and is released to the back yoke 6 abutting on the yoke 4. Thereafter, the magnetic flux is applied to the adjacent coil 3 arranged in the circumferential direction or the coil position arranged at a position skipped by one with respect to the position escaping to the back yoke 6. 4, the thin portion 4 f, the thick portion 4 e, and the inner peripheral surface 4 h, and finally return to the permanent magnet 12. Therefore, coil 3
, An electromagnetic force acts between the coil 3 and the permanent magnet 12, and the rotor 2 can rotate with respect to the stator 7.

Therefore, the yoke 4, the coil 3, and the back yoke 6 are formed to have an outer diameter with respect to the permanent magnet 12 so as to convert the magnetic flux from the permanent magnet 12 fixed to the rotating shaft 10 from the radial direction to the axial direction. Therefore, the flat brushless motor 1 having a thin axial direction can be realized. In this case, the rotor 2 is disposed inside the yoke 4 that supports the coil 3, the rotor diameter is reduced, and the inertia of the rotor 2 can be reduced. Therefore, the motor can be started and stopped reliably.

The motor thinned in the axial direction configured as described above can be integrated with a circuit board such as a control device for controlling an electronic device.

[0025]

According to the present invention, a rotary shaft supported on a base member and serving as a rotor, a permanent magnet which rotates integrally with the rotary shaft and is magnetized in the radial direction, and provided on the outer diameter of the permanent magnet A plurality of coils arranged in the circumferential direction, a first yoke supporting one side of the coil in the axial direction, and converting a direction of a magnetic flux emitted from the permanent magnet from a radial direction to an axial direction; Since the second yoke is provided on the side, the permanent magnet that rotates integrally with the rotor is smaller than the first yoke. In this case, the magnetic flux in the radial direction from the permanent magnet can be converted in the axial direction and transmitted from the first yoke to the second yoke. Therefore, the rotor diameter can be made smaller than the plurality of coils arranged in the circumferential direction. For this reason, the inertia of the rotor does not increase, and a flat brushless motor with a reduced moment of inertia of the rotor is obtained.

In this case, the coil is an air-core coil that is open in the axial direction, the first yoke has a coil support for supporting the air-core coil, and the coil support transfers the magnetic flux in the axial direction of the coil to the second coil. If it is transmitted to the yoke, the magnetic flux of the magnetic field in the axial direction of the coil can be efficiently increased by the coil support portion of the first yoke. Therefore, a highly efficient flat brushless motor is obtained.

Further, if the second yoke is formed in a flat disk shape,
Even if the second yoke is arranged to face the coil, it does not increase in the axial direction.

Further, the first yoke has a thick portion and a thin portion in the axial direction, and when the coil is disposed on the thin portion, the thickness is substantially the same as the thickness of the thick portion in the axial direction. if,
A flat brushless motor thinned in the axial direction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a flat brushless motor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a relationship between a coil and a yoke arranged in a circumferential direction of the flat brushless motor according to the first embodiment of the present invention.

FIG. 3 is an assembly diagram showing an assembly state of a flat brushless motor according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of the assembled flat brushless motor shown in FIG.

FIG. 5 is a cross-sectional view showing the configuration of a conventional example of a flat brushless motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat brushless motor (motor) 2 Rotor 3 Coil (air-core coil) 4 Yoke (1st yoke) 4a, 4g Coil support part 4e Thick part 4f Thin part 6 Back yoke (second yoke) 7 Stator 10 Rotating shaft 12 Permanent magnet 20 Housing (base member)

Continued on the front page F term (reference) 5H002 AA01 AB06 AE08 5H019 AA08 CC03 CC06 DD06 EE13 5H603 AA01 AA03 AA09 BB01 BB10 BB12 CA01 CA05 CB01 CC14 CC17 CD01 CD04 CD21 CE01

Claims (5)

[Claims] 1. A base member, a rotor rotatably supported on the base member, a permanent magnet fixed to an outer peripheral surface of the rotor and magnetized in a radial direction of the rotor, and A flat motor, comprising: a stator disposed on an outer peripheral side of the permanent magnet; and a plurality of coils disposed on the stator in a circumferential direction of the rotor. A first yoke disposed on one side in the axial direction of the coil to convert a magnetic flux generated by the magnet from a radial direction to an axial direction with respect to the coil; and an axial direction of the coil. And a second yoke disposed on the other side. 3. The coil is an air-core coil, the first yoke has a coil support for supporting the coil,
The flat motor according to claim 2, wherein the coil supporting portion transmits an axial magnetic flux passing through the coil to the second yoke. 4. The first yoke has a thick portion and a thin portion, and when the coil is disposed on the thin portion, the thickness is substantially the same as the thickness of the thick portion in the axial direction. The flat motor according to claim 2 or 3, wherein: 5. The flat motor according to claim 2, wherein the second yoke has a shape of a flat disk.