JP3214913B2 - Radial type outer rotor type brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial outer rotor type brushless motor suitable for use in a headphone type tape recorder which does not like vibration.

[0002]

2. Description of the Related Art In a headphone type tape recorder or the like, an axial type brushless motor is often used as a tape driving motor in order to minimize vibration generated from the inside.

An axial type brushless motor is a type of a motor in which a flux (field magnetic flux) is generated in parallel with a rotating shaft, and an example thereof is shown in FIG. To briefly explain the configuration, reference numeral 11 denotes a motor housing to which a bearing mounting member 12 is fixed. The rotating shaft 13 is supported by the mounting member 12 via a bearing (oil-less metal) 14.

A holder 15 having a cylindrical pulley is fixedly mounted on the upper end of the rotating shaft 13, and a rotor case 16 is mounted on one end of the holder 15 and magnetized to a predetermined number of poles. The disc-shaped magnet 17 is placed and fixed.

The magnet 17 functions as a rotor magnet, and a coil substrate 19 as a field coil is fixed at a predetermined gap so as to face the magnet 17. The coil substrate 19 has a coil conductor formed in a predetermined pattern.

The coil board 19 is fixed to the motor housing 11 as shown in the figure. Reference numeral 18 denotes a yoke constituting a magnetic circuit, and reference numeral 20 denotes a drive belt. The motor 10 configured as described above is fixed to a chassis 22 provided inside an apparatus cabinet 21.

[0007]

Since the axial type brushless motor 10 has a small flat structure,
It is suitable to be applied to a small electronic device such as a headphone type tape recorder, but in this type of brushless motor 10, the thickness of the coil substrate 19 is about 0.4 mm.
Very thin.

Further, a three-phase switching current (motor driving current) is supplied to the field coil for a brushless configuration, and the switching current may cause the coil substrate 19 itself to vibrate. Since this vibration becomes noise, the noise becomes a serious problem when it is mounted on a small tape recorder or the like as described above.

Next, the magnet 17 must be magnetized so as to have a predetermined number of poles. The larger the number of poles, the narrower the pitch between the poles, so that the magnetization process becomes difficult in proportion to the number of poles, and becomes difficult in proportion to miniaturization. In particular, when a device that is oriented to miniaturization and has a large number of poles is required, the pitch between the poles must be further reduced, so that the magnetization process becomes more difficult.

[0010] Further, because of the axial type, a magnet 17 is disposed on the upper surface of the rotor case 16, a coil substrate 19 is disposed on the upper surface, and a yoke 18 for forming a magnetic circuit is disposed on the upper surface. (Not shown) must be arranged outside the brushless motor 10. Therefore, the brushless motor 10 itself cannot be reduced in size at present considering the circuit board and the like.

Therefore, the present invention has been made to solve such a conventional problem, and has low noise, easy magnetizing process, and can be downsized. The present invention proposes a radial type outer rotor type brushless motor that can be reduced.

[0012]

In order to solve the above-mentioned problems, according to the present invention, the number of poles of a cylindrical magnet attached to an outer rotor side is set to 2p, and the magnet is attached to a stator side yoke holder so as to face the magnet. The relationship between the obtained field coil number n is 2p: n = 4: 3 or 2p: n
= 10: 6, the field coil is a sheet coil formed of a coil conductor, and one of the field coil regions corresponding to an electrical angle of 360 ° in the sheet coil. A part or the whole is formed as a power supply terminal part, and an outer peripheral surface of the yoke facing the power supply terminal part is cut off.

[0013]

In FIG. 1, a sheet coil 35 is mounted on the outer peripheral surface of a yoke holder 31 arranged on the stator side. Since the sheet-shaped coil 35 is adhered to the yoke holder 31, even if a switching current is supplied to a field coil (coil conductor portion) 38 (FIG. 6) formed on the sheet-shaped coil 35, the sheet-shaped coil 35 is thereby formed. There is no vibration.

Since the magnet 40 is mounted on the outer rotor side facing the sheet-shaped coil 35, the magnet 40
Has a relatively long circumferential length, which facilitates magnetization in the circumferential direction.

The number of poles 2p of the cylindrical magnet 40 and the magnet 4
The relationship between 0 and the number n of the field coils of the sheet-shaped coil 35 facing each other is 2p: n = 4: 3 or 2p: n = 10: 6.
For example, when 20:12 is selected, as shown in FIG. 7, a field coil area 55 (shown by a broken line; this area is hereinafter referred to as an idle portion) of the sheet-like coil 35 corresponding to an electrical angle of 360 degrees is selected. Can be omitted.

The sheet coil 3 corresponding to the gap 55
A part or all of 5, and in this example, all of them are used as the power supply terminal 37. The power supply terminal 37 is bent as shown in FIG. 9 and is led out of the outer rotor as shown in FIG.

The yoke holder 31 corresponding to the gap 55
The outer peripheral surface of the yoke 33 (including the yoke 33) is cut to form the notched end surface 60. The cutting of the outer peripheral surface reduces iron loss at that portion, so that the motor current consumption is reduced. This improves motor efficiency and reduces heat generation.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a radial type outer rotor type brushless motor according to the present invention.

FIG. 1 is a longitudinal sectional view showing an example of a radial type outer rotor type brushless motor 30 according to the present invention in which a power supply terminal portion is led out of the outer rotor.

Since the brushless motor 30 according to the present invention is of the outer rotor type, the components of the stator are disposed inside. Therefore, the bearing mounting member 12 is fixed to the motor housing 11 as shown in FIG.
Is fixed to the mounting member 12 via a bearing 14 made of oilless metal or the like.

A yoke holder 31 is provided on the outer periphery of the mounting member 12 so as to surround the mounting member 12, and is fixed to the motor housing 11. The yoke holder 31 is formed as a hollow bottomed cylindrical body as shown in the figure, and the bottomed portion is placed on the motor housing 11 side.

A recess 32 is formed in a part of the outer peripheral surface of the yoke holder 31 along the circumferential direction, and a disk-shaped and thin yoke 33 is stacked and housed therein. In this example, eight sheets are stacked. The reason why the yoke 33 is formed into a thin plate and laminated and integrated is to reduce eddy current loss.

A sheet-shaped coil 35 having a predetermined width and functioning as a field coil is attached and fixed to the outer peripheral surface of the yoke holder 31 so as to cover the yokes 33 stored in a stacked state. As the sheet-shaped coil 35, a flexible coil substrate 39 (FIG. 6) is used so that it can be attached to the outer peripheral surface of the yoke holder 31. The thickness of the coil substrate 39 is, for example, about 0.2 to 1.0 mm. The power supply terminal portion 37 of the sheet-shaped coil 35 is fixed to the motor housing 11 while being bent from the stator side and led out of the outer rotor.

The gap 55 (see FIG. 7) of the sheet-shaped coil 35 used as the power supply terminal 37 is an area having an electrical angle of 360 degrees (corresponding to one unit of the u, v, and w phases). Since this does not function as a region for rotating the rotor, as shown in FIGS.
1 and the idle portion 5 of the yoke 33 accommodated therein.
The portion facing 5 is cut to form a notched end face 60. An advantage of the notch end face 60 is that iron loss at this portion can be reduced as described later.

The constituent members of the outer rotor are arranged so as to face the sheet coil 35. Therefore, the cylindrical case 41 is attached to the holder 15 attached and fixed to the tip of the rotating shaft 13, and the ring-shaped magnet 40 having a predetermined width is attached and fixed to the inner surface thereof. The relative positional relationship between the magnets 40 is selected so that the magnets 40 face the sheet-shaped coil 35 with a small gap.

The holder 15 also functions as a pulley, and the torque of the motor is transmitted to the driven portion by the drive belt 20 via the pulley portion. Sheet coil 35 described above
The relationship between and the magnet 40 will be described later.

As described above, when a hollow and bottomed cylindrical body is used as the yoke holder 31 as shown in the figure, an internal space 50 as shown in the figure is formed in the stator. The circuit board 23 on which circuit components necessary for driving the brushless motor 30 are mounted and fixed in the internal space 50. Although FIG. 1 shows an example in which only one circuit board 23 is housed, a plurality of circuit boards can be housed, and other circuit components and members can be housed.

Other uses of the internal space 50 include, for example, mounting a precision bearing mechanism for a high-precision motor. That is, when the brushless motor 30 requires a high shaft accuracy, a precision bearing mechanism may be disposed in the yoke holder using the internal space 50 instead of the circuit board 23 and the like. As a result, a highly accurate motor can be configured without increasing the size of the motor itself.

The relationship between the number of poles 2p and the number of field coils n of the brushless motor 30 according to the present invention is 2p: n = 4: 3.
Alternatively, 2p: n is selected as an integral multiple of 10: 6.

The principle of the motor which is the basis of the present invention employing the former (2p: n = 4: 3) configuration will be described below with reference to FIG.

The ring-shaped magnet 40 shown in FIG.
Are uniformly arranged in four poles over the entire circumference of 360 degrees, and are arranged in a positional relationship such that the pole pitch is 90 degrees (360 degrees / 4 = 90 degrees). If the width of each magnetic pole is l (ell) as shown in the figure, the coil width (pitch between adjacent front and rear coil sides) of the sheet-shaped coil 35 provided opposite thereto is also shown in FIG. As shown in (b), it is selected to be substantially l. This corresponds to an efficient, so-called full-volume winding.

Therefore, the three-phase coils of u, v, and w each have an angle of 30 ° ((360 ° -90 ° ×
3) Since they are arranged with a phase difference of (3 = 30 degrees), the space between the adjacent coils can be effectively used.

As an example of the use of the coil space, for example, it can be used as a space for increasing the number of coil turns on the same surface in order to obtain a rotational torque, and for the same purpose, the surface of the sheet-like coil 35 will be described in detail later. Also, it can be used as a space where a coil is arranged on the back surface and a through hole for electrically connecting the front and back surfaces is provided. In the through hole configuration, the vertical dimension of the sheet coil 35 can be set low.

The magnet 40 and the sheet-shaped coil 35
When the magnet 40 moves in the direction of the arrow in the drawing, the relative positions of the coils u,
The electromotive force generated in each of v and w is as shown in FIG.

If the switching current shown in FIG. 2D is supplied to each of the coils u, v, w of the sheet-like coil 35, a smooth rotation of the motor can be obtained.

The principle of the motor which is the premise of the present invention employing the latter (2p: n = 10: 6) configuration will be described below with reference to a developed view shown in FIG.

The ring-shaped magnet 40 shown in FIG.
Are equally distributed over 360 degrees so that the pole pitch is 36 degrees (360 degrees / 10 = 36 degrees).
It is arranged in the following positional relationship.

Assuming that the width of each magnetic pole is l ', the coil width of the sheet-like coil 35 provided opposite thereto (the pitch between adjacent coil sides before and after) is also shown in FIG.
As shown in (b), it is selected to be approximately l '. This is equivalent to the so-called full-volume winding, which is as efficient as described above.

Therefore, the three-phase coils of u, v, and w are adjacent to the adjacent coils by 24 degrees ((360 degrees−36 degrees ×
6) Since the arrangement is performed with a phase difference of (6 = 24 degrees), the space between the adjacent coils can be effectively used similarly to the above-described configuration of 2p: n = 4: 3.

Such a magnet 40 and the sheet-like coil 35
When the magnet 40 moves in the direction of the arrow in the drawing, the relative positions of the coils u,
The electromotive force generated in each of v and w is as shown in FIG. If the switching current shown in FIG. 3D is supplied to each of the coils u, v, w of the sheet-like coil 35, smooth rotation of the motor can be obtained.

FIG. 4 is a view for explaining the present invention, and is an example of a cross-sectional view of the motor when (2p: n = 4: 3) is adopted among the above-mentioned examples. In the drawing, 2p = 1
6 shows a configuration when n = 12. FIG. 5 is a schematic developed view showing the positional relationship between the magnet 40 and the sheet coil 35 shown in FIG.

Since the ring-shaped magnets 40 are uniformly arranged in 16 poles over the entire circumference of 360 degrees, the pole pitch is 2
They are arranged in a positional relationship of 2.5 degrees (360 degrees / 16 = 22.5 degrees). The coil width (pitch between the coil side and the coil side) of the sheet-like coil 35 provided opposite thereto is also 2
Since the coils are arranged at approximately the same pitch of 2.5 degrees, each adjacent coil is 7.5 degrees ((360 degrees-22.5 degrees × 12)).
(12 = 7.5 degrees).

FIG. 6 is a developed view showing a specific example of the sheet coil 35 shown in FIGS. 4 and 5, and shows the relationship between the number of poles 2p and the number of phases n as an integral multiple of 2p: n = 4: 3. Is 1
An example in the case of selecting 6:12 is shown.

The sheet-shaped coil 35 is formed in a radial direction (rotation) by a coil conductor portion 38, that is, a field coil formed on the front surface (A surface) and the back surface (B surface) of the coil substrate 39 by a known etching technique. A rotating magnetic field (relative to the shaft 13) is generated, and the rotor is rotated by the rotating magnetic field.

The field coil formed on the coil substrate 39 is configured as a patterned coil conductor 38 as shown in the figure, and 12 unit coil conductors are formed.
3 is connected so as to be three phases of u phase, v phase and w phase.
A three-phase switching current (motor drive current) is supplied to the phase coil conductor 38.

The coil substrate 39 is provided with the power supply terminal portion 37 functioning as a switching current supply terminal as described above, and is bent from the stator side and fixed to the motor housing 11 as shown in FIG. Power can be supplied to the sheet-shaped coil 35 without affecting it.

Since the sheet-shaped coil 35 is firmly adhered to the outer peripheral surface of the yoke holder 33, the sheet-shaped coil 3
Even if 5 is very thin, no oscillation is caused by the switching current supplied thereto.

The surface B of the sheet-shaped coil 35 is shown in a see-through state from the surface A for convenience of explanation. The sheet-shaped coil 35 is formed in a state where the A surface and the B surface are overlapped, and the A surface and the B surface are electrically connected to each other through through holes. The reason that each coil is constituted by a pair of coils on the front and back sides is to gain rotational torque.

As described above, the three-phase coils of u, v, and w formed on the sheet-shaped coil 35 are arranged with a phase difference of 7.5 degrees from the adjacent coils, respectively. When the through holes are provided, the vertical dimension of the sheet-shaped coil 35 can be set low, so that the size of the motor itself can be reduced as a whole.

As shown in FIG. 1, the magnet 40 is a ring-shaped plate-like magnet having a predetermined width and thickness. Therefore, the magnetizing direction is the circumferential direction. Therefore, the magnetization of the magnet is simpler than that of a magnet used in an axial type brushless motor.

This is because, in the axial type, the magnetized area of the magnet is a fan-shaped area directed in the radial direction. Therefore, as the number of poles increases and as the size becomes smaller, the magnetized pitch at the inner diameter of the magnet becomes very large. The magnetizing process is very troublesome due to the narrowing.

In the radial type, the unit rectangular area may be uniformly magnetized in the circumferential direction of the magnet 40 located at the radial portion of the outer rotor (corresponding to the axial outer diameter portion). Even if the number of magnets increases or the size becomes smaller, the magnetizing interval does not become too narrow. As a result, the magnetizing process is simpler than that of the axial type magnet.

FIG. 7 is provided for describing the present invention. The relationship between the number of poles 2p and the number of phases n is selected to be 20:15, which is an integral multiple of 2p: n = 4: 3, and is indicated by a broken line. As shown in the drawing, the positional relationship between the magnet 40 of the brushless motor 30 and the sheet-shaped coil 35 when one unit of each of the u, v, and w phases in the field coil region 55 is deleted is shown as a developed view.

In this case, each one of the u, v, and w phases indicated by a broken line
Since the relationship between the number of poles 2p and the number of phases n satisfies 2p: n = 4: 3 in the remaining portion even after the unit is deleted, the motor functions sufficiently as a motor. At this time, the ring-shaped magnets 40 are evenly arranged in 20 poles over the entire circumference of 360 degrees, so that the pole pitch is 18 degrees (360 degrees ÷ 20 = 1).
8 degrees).

The coil width (pitch between coil sides) of the sheet-shaped coil 35 provided opposite thereto is also 18
Since the coils are arranged at approximately the same pitch, the adjacent coils are arranged with a space formed by an angle of 6 degrees ((360 degrees−18 degrees × 15) ６15 = 6 degrees). The region (corresponding to the idle portion 55) has a space of 72 degrees.

FIG. 8 is a developed view showing a specific example of the sheet coil 35 used in the present invention. 6, the B surface of the sheet-shaped coil 35 shows a state seen through from the A surface side for convenience of description, and the sheet-shaped coil 35 is formed by superimposing the A surface and the B surface on the A surface. Surface B and surface B are electrically connected to each other via through holes.

As described above, 72 degrees ((18 degrees + 6 degrees) × 3 = 7) obtained by deleting one unit of each of u, v, and w phases.
Since the coil conductor portion is shortened by 2 degrees), the power supply terminal portion 37 is arranged using the idle portion 55 corresponding to 72 degrees.

In the case of FIG. 6, the power supply terminal portion 37 is formed so as to protrude below the coil substrate 39. In the case of FIG. 8, however, one end of the coil substrate 39 is extended and the power supply terminal portion 37 is formed. Done.

As described above, the coil substrate 39 and the power supply terminal 3
7 are formed linearly, and when the sheet-shaped coil 35 is adhered to the outer peripheral surface of the yoke holder 31, the power supply terminal portion 37 cannot be led out (outside the outer rotor) as it is.

Then, the power supply terminal 37 is bent along the bending lines r and s as shown by the broken lines in FIGS. The power supply terminal 37 is bent 90 ° with respect to the coil substrate 39 from the state shown in FIG. 9A by the bending line r having an angle of about 45 ° with respect to the coil substrate 39 as shown in FIG. Therefore, as a result of this bending, the power supply terminal 37 becomes parallel to the rotating shaft 12.

As a result of being further bent at a right angle along the bending line s, as shown in FIG.
Since the front end side of the bent line s is parallel to the chassis 11, the power supply terminal 37 can be led out of the outer rotor as desired as shown in FIG.

When the power supply terminal portion 37 is bent from the bending line r, the bent portion is firmly attached and fixed to the outer peripheral surface of the yoke holder 31 and further corresponds to the power supply terminal portion 37 for the purpose of reducing eddy current loss. The outer peripheral surface of the yoke holder 31 is cut to form a notched end surface 60 as shown in FIG.

Since the idle portion 55 does not have a field coil and does not constitute a magnetic circuit, it is not necessary to dispose the yoke 33 at a portion facing the idle portion 55. Therefore, the notch end face 6 is formed on the yoke holder 31 facing the play portion 55.
When 0 is formed, no eddy current loss, which is a type of iron loss in the idle portion 55, occurs. Due to the reduction of the eddy current loss, the motor current consumption is reduced, and the motor driving efficiency is also improved. Fever is also reduced.

The relationship between the number of poles 2p of the magnet 40 and the number of phases n of the sheet-like coil 35 is merely an example, and the integer value may be other than the above-mentioned values. Since the motor can function as a motor if it is deleted, the idle portion created by the deletion can be effectively used.

[0065]

As described above, in the brushless motor according to the present invention, the radial rotor type outer rotor system is employed, and the relationship between the number of magnet poles and the number of phases of the field coil is set to a predetermined relationship. By setting, a part of the sheet-shaped coil can be used as a power supply terminal portion.

According to this, the sheet-like coil can be adhered and fixed to the outer peripheral surface of the yoke holder, so that the vibration generated by the motor driving switching current supplied to the sheet coil can be effectively suppressed. Therefore, a brushless motor with low noise can be provided.

Since the magnets are arranged on the outer rotor side, the magnets can be easily magnetized, and a motor configuration suitable for multipolarization and miniaturization can be provided.

By bending and using a part of the power supply terminal, the power supply terminal can be easily led out to the outer portion of the outer rotor, so that the assembling work can be performed efficiently and the power supply terminal can be damaged. It has the benefits that can be done without. In the present invention, since the notch end face obtained by cutting off a part of the yoke holder including the yoke is formed, the iron loss is reduced and the motor current consumption can be suppressed accordingly. Fever is also reduced.

Therefore, the present invention is very suitable for application to a headphone-type small tape recorder which does not like vibration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a radial outer rotor type brushless motor according to the present invention.

FIG. 2 is a diagram illustrating the principle of a motor.

FIG. 3 is a diagram showing another principle of the motor.

FIG. 4 is a cross-sectional view showing an example of a radial outer rotor type brushless motor used for describing the present invention.

FIG. 5 is a diagram showing a relative positional relationship between a magnet and a sheet coil at that time.

FIG. 6 is a configuration diagram showing an example of a sheet-like coil used in a brushless motor used for describing the present invention.

FIG. 7 is a view showing a relative positional relationship between a magnet and a sheet coil used in the brushless motor according to the present invention.

FIG. 8 is a configuration diagram showing a specific example of a sheet coil used in a brushless motor.

FIG. 9 is a diagram illustrating an example of a bent state of a sheet coil.

FIG. 10 is a cross-sectional view showing an example of a radial outer rotor type brushless motor according to the present invention.

FIG. 11 is a longitudinal sectional view showing an example of a conventional axial type brushless motor.

[Description of Signs] 10, 30 Brushless motor 11 Motor housing 13 Rotating shaft 31 Yoke holder 33 Yoke 35 Sheet coil 37 Power supply terminal 39 Coil board 40 Magnet 55 Playing part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-178148 (JP, A) JP-A-4-172952 (JP, A) JP-A-4-178156 (JP, A) JP-A-4-178 200248 (JP, A) JP-A-57-85564 (JP, A) JP-A-1-315244 (JP, A) JP-A-63-253322 (JP, A) JP-A-3-3644 (JP, A) JP-A-60-141157 (JP, A) JP-A-60-194735 (JP, A) JP-A-4-35675 (JP, U) JP-A-3-50966 (JP, U) JP-A-2-103779 (JP, U) JP-A-2-103780 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 29/00, 21/00 H02K 3/26 H02K 5/22

Claims (1)

(57) [Claims] 1. The relationship between the number of poles 2p of a cylindrical magnet mounted on the outer rotor side and the number n of field coils mounted on a stator-side yoke holder so as to face the magnet is 2p: n = 4. : 3 or 2p: n = 10: 6
A part or all of the field coil region corresponding to an electrical angle of 360 ° of the sheet coil is formed as a power supply terminal portion, and the outer peripheral surface of the yoke facing the power supply terminal portion is selected. A radial outer rotor type brushless motor characterized in that the brushless motor is cut off.