JPH0678506A - Radial type outer rotor type brushless motor - Google Patents

Abstract

PURPOSE:To provide a brushless motor, which is hardly vibrated and can be miniaturized. CONSTITUTION:The relationship of the number of poles 2p of a cylindrical magnet 40 installed on the outer rotor side and the number of field coils (n) mounted to a stator-side yoke holder 31 is selected in the integral times of 2p:n=4:3 or 2p:n=10:6, a sheet-shaped coil 35 formed by a coil conductor is used as the field coil while the yoke holder 31 arranged on the inside is constituted as a hollow bottomed cylindrical body, and a circuit board 23, etc., can be interior-finished into an internal space 50 formed by the hollow bottomed cylindrical body. Since the sheet-shaped coil 35 is stuck onto the outer circumferential surface of the yoke holder 31, the sheet-shaped coil is not vibrated by switching currents fed for driving a motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial type outer rotor type brushless motor suitable for application to a headphone type tape recorder or the like 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 avoid internal vibrations as much as possible.

The axial type brushless motor is a type of motor in which flux (field magnetic flux) is generated in parallel with the rotating shaft, and an example thereof is shown in FIG. The structure will be briefly described. Reference numeral 11 denotes a motor housing, to which the bearing mounting member 12 is fixed. The rotary shaft 13 is supported by the mounting member 12 via a bearing (oilless metal) 14.

A holder 15 having a cylindrical pulley is attached and fixed to the upper end of the rotary shaft 13, and a rotor case 16 is attached to one end of the holder 15 and magnetized to a predetermined number of poles. The disk-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 with a predetermined gap so as to face the magnet 17. The coil board 19 is formed by forming a coil conductor in a predetermined pattern.

The coil board 19 is fixed to the motor housing 11 as shown in the figure. Reference numeral 18 is a yoke forming a magnetic circuit, and 20 is a drive belt. The motor 10 thus configured is fixed to the chassis 22 provided inside the device cabinet 21.

[0007]

Since the axial type brushless motor 10 has a small and flat construction,
It is suitable for application to small electronic devices such as headphone type tape recorders, but in this type of brushless motor 10, the coil substrate 19 has a thickness of about 0.4 mm.
Very thin.

Further, since the field coil is provided with a three-phase switching current (motor drive current) for the brushless construction, the coil substrate 19 itself may vibrate due to this switching current. Since this vibration causes noise, this noise becomes a serious problem when it is mounted on the above-mentioned small tape recorder or the like.

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 magnetizing process becomes more difficult in proportion to the number of poles and the smaller in size. In particular, when miniaturization is required and a pole having a large number of poles is required, the pitch between the poles must be further narrowed, so that the magnetizing process becomes difficult.

Further, since it is an axial type, the magnet 17 is arranged on the upper surface of the rotor case 16, the coil board 19 is arranged on the upper surface thereof, and the yoke 18 for forming a magnetic circuit is arranged on the upper surface thereof. (Not shown) must be placed outside the brushless motor 10. Therefore, in consideration of the circuit board and the like, the current situation is that the brushless motor 10 itself cannot be downsized so much.

Therefore, the present invention solves the above-mentioned conventional problems, and proposes a radial type outer rotor type brushless motor which is small in noise, can be easily magnetized, and can be miniaturized. Is.

[0012]

In order to solve the above-mentioned problems, according to the present invention, the number of poles 2p of a disk-shaped magnet attached to the outer rotor side and the stator-side yoke holder so as to face the magnet. The relation with the number of attached field coils n is 2p: n = 4: 3 or 2p: n
= 10: 6, and the field coil is a sheet-shaped coil made of a coil conductor, and the yoke holder arranged inside is a hollow bottomed cylindrical body. A circuit board or the like is internally provided in an internal space formed by the hollow bottomed tubular body.

[0013]

In FIG. 1, the sheet coil 35 is attached to the outer peripheral surface of the yoke holder 31 arranged on the stator side. Since the sheet-shaped coil 35 is attached to the yoke holder 31, even if a switching current is supplied to the field coil (coil conductor portion) 38 (FIG. 6) formed on the sheet-shaped coil 35, the sheet-shaped coil 35 can be formed by the switching current. It does not vibrate.

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

Since the outer rotor type is used, a relatively wide internal space 50 can be formed depending on how to select the shape of the yoke holder 31 on the stator side. This internal space 5
The circuit board 23 and the like are internally installed in 0. Since the circuit board 23 is a board for controlling the brushless motor,
As a result, it is possible to save space when mounting the device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of a radial type outer rotor type brushless motor according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing an example of a radial type outer rotor type brushless motor 30 according to the present invention.

Since the brushless motor 30 according to the present invention is of the outer rotor type, the constituent members of the stator are arranged 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 arranged 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 configured as a hollow bottomed cylindrical body as shown in the figure, and the bottomed portion is placed on the motor housing 11 side.

A concave portion 32 is formed on a part of the outer peripheral surface of the yoke holder 31 so as to make one round along the circumferential direction, and a disk-shaped thin plate-shaped yoke 33 is stacked and accommodated therein. In this example, eight sheets are stacked. The reason why the yoke 33 is formed into a thin plate and laminated and combined is to reduce the 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 housed 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 bent from the stator side and fixed to the motor housing 11.

The constituent members of the outer rotor are arranged so as to face the sheet-shaped coil 35. Therefore, the cylindrical case 41 is attached to the holder 15 fixed to the tip of the rotary shaft 13, and the ring-shaped magnet 40 having a predetermined width is fixed to the inner surface of the case 41. in this case,
The relative positions of the magnets 40 are selected so as to face the sheet-shaped coil 35 with a slight gap.

The holder 15 also functions as a pulley, and the driving belt 20 transmits the rotational force of the motor to the driven portion via the pulley portion. Sheet-shaped coil 35 described above
The relationship between the magnet 40 and the magnet 40 will be described later.

As described above, when the yoke holder 31 is a hollow cylindrical body having a bottom as shown in the figure, an internal space 50 as shown in the figure is formed in the stator. In this internal space 50, the circuit board 23 mounted with circuit components necessary for driving the brushless motor 30 and the like are housed and fixed. Although only one circuit board 23 is accommodated in the drawing, a plurality of circuit boards can be accommodated as well as other circuit components and members.

Another usage of the internal space 50 is mounting a precision bearing mechanism for a high precision motor, for example. That is, when the brushless motor 30 is required to have high axial accuracy, the internal space 50 may be used to dispose the precision bearing mechanism in the yoke holder instead of the circuit board 23 and the like. As a result, a highly accurate motor can be constructed 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, it is selected to be an integral multiple of 2p: n = 10: 6.

The principle of the motor adopting the former configuration (2p: n = 4: 3) will be described below with reference to FIG. 2 showing a development view.

The ring-shaped magnet 40 shown in FIG.
Since the four poles are evenly arranged so as to cover the entire circumference of 360 degrees, the pole pitch is 90 degrees (360 degrees / 4 = 90 degrees). When the width of each magnetic pole is set to 1 as shown in the same figure, the coil width of the sheet-shaped coil 35 (the pitch between adjacent coil sides before and after adjoining) is also shown in FIG. As shown in FIG. This corresponds to an efficient, so-called full-pitch winding.

Therefore, the u, v, and w three-phase coils are adjacent to the adjacent coils by 30 degrees ((360 degrees-90 degrees x
Since 3) ÷ 3 = 30 degrees), the coils are arranged with a phase difference of (3) = 30 °), so that the spaces of the coils adjacent to each other can be effectively used.

For example, in order to increase the rotational torque, the number of coil turns on the same surface is increased, and for the same purpose, the details will be described later. It can also be used as a space for providing a through hole for connecting to. With the through-hole configuration, the vertical dimension of the sheet coil 35 can be set low.

Such a magnet 40 and a sheet coil 35
When the magnet 40 moves in the direction of the arrow in the drawing in the relative positional relationship of the coil u of the sheet coil 35,
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 coil 35, smooth rotation of the motor can be obtained.

The principle of the motor adopting the latter (2p: n = 10: 6) configuration will be described below with reference to the development view shown in FIG.

A ring-shaped magnet 40 shown in FIG.
Is distributed evenly over the entire circumference of 360 degrees, so the pole pitch is 36 degrees (360 degrees / 10 = 36 degrees).
It is arranged in the following positional relationship.

When the width of each magnetic pole is l ', the coil width of the sheet-like coil 35 (the pitch between adjacent coil sides before and after adjoining) is also shown in FIG.
As shown in (b), it is selected to be substantially l '. This corresponds to the so-called full-pitch winding, which is as efficient as the above.

Therefore, the coils of three phases u, v, and w are adjacent to the adjacent coils by 24 degrees ((360 degrees-36 degrees x
6) ÷ 6 = 24 degrees), the adjacent coils can be effectively used as in the case of the above-described 2p: n = 4: 3 configuration.

Such a magnet 40 and a sheet coil 35
When the magnet 40 moves in the direction of the arrow in the drawing in the relative positional relationship of the coil u of the sheet coil 35,
Electromotive forces generated in v and w are 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-shaped coil 35, smooth rotation of the motor can be obtained.

FIG. 4 shows (2p: n =
Fig. 4 is an example of a cross-sectional view of a motor when 4: 3) is adopted, and shows the configuration when 2p = 16 and n = 12 are selected in the figure. FIG. 5 is a schematic development view showing the positional relationship between the magnet 40 and the sheet-shaped coil 35 shown in FIG.

Since the ring-shaped magnets 40 are evenly arranged with 16 poles so as to cover 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 coil sides) of the sheet-shaped coil 35 provided facing this is also 2
Since they are arranged at substantially the same pitch of 2.5 degrees, each adjacent coil has 7.5 degrees ((360 degrees-22.5 degrees x 12) ÷
They are arranged with a space (phase difference) formed by an angle of 12 = 7.5 degrees.

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

In the present example, the sheet-shaped coil 35 is formed 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 in the radial direction (with respect to the rotating shaft 13) is generated to rotate the rotor.

The field coil formed on the coil substrate 39 is formed as a patterned coil conductor portion 38 as shown in the drawing, and 12 unit coil conductor portions are formed.
3 are connected so that there are 3 phases of U phase, V phase and W phase
Three-phase switching currents (motor drive currents) are supplied to the phased coil conductor portions 38.

The coil board 39 is provided with a power supply terminal portion 37 which functions as a switching current supply terminal, and is bent from the stator side and fixed to the motor housing 11 as shown in FIG. 1 to affect the outer rotor constituent members. Instead, power can be supplied to the sheet coil 35.

Since the sheet coil 35 is firmly attached to the outer peripheral surface of the yoke holder 33, the sheet coil 3
Even if 5 is very thin, it will never oscillate due to the switching current supplied to it.

For convenience of explanation, the B-side of the sheet-shaped coil 35 is shown as seen through from the A-side, and the sheet-shaped coil 3 is shown.
5 is formed in a state in which the A surface and the B surface are overlapped with each other.
The surface and the surface B are electrically connected to each other through the through holes. The reason why each coil is composed of a pair of front and back coils is to obtain a rotational torque.

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

As shown in FIG. 1, the magnet 40 is a ring-shaped plate magnet having a predetermined width and thickness, so that its magnetizing direction is the circumferential direction. Therefore, magnetization of the magnet becomes easier as compared with the magnet used in the axial 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, and therefore the magnetized pitch in the inner diameter portion of the magnet becomes very large as the number of poles increases and as the size decreases. The magnetizing process becomes 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 in the radial portion of the outer rotor (corresponding to the outer diameter portion of the axial type). The magnetizing interval does not become too narrow even if the number increases or the size becomes smaller. As a result, the magnetizing process is simpler than that of an axial magnet.

In FIG. 7, the relationship between the number of poles 2p and the number of phases n is 2
20:15 which is an integer multiple of p: n = 4: 3,
In addition, as shown by a broken line, the positional relationship between the magnet 40 of the brushless motor 30 and the sheet coil 35 when one unit of each U, V, W phase is deleted is shown as a developed view.

In this case, each one of the u, v, and w phases indicated by the broken line
Even if the unit is deleted, the relationship between the number of poles 2p and the number of phases n in the remaining portion satisfies 2p: n = 4: 3, so that the motor functions sufficiently as a motor. At this time, the ring-shaped magnets 40 are evenly arranged with 20 poles so as to cover 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-like coil 35 provided opposite to this is 18
Since the coils are arranged at substantially the same pitch, the coils are arranged with a space of 6 ° ((360 ° -18 ° × 15) ÷ 15 = 6 °) with the adjacent coils. Is a space of 72 degrees.

FIG. 8 shows the sheet coil 35 shown in FIG.
It is a development view showing a specific example of. Similar to FIG. 6, the B-side of the sheet-shaped coil 35 is shown as seen through from the A-side for convenience of explanation, and the sheet-shaped coil 35 is formed by overlapping the A-side and the B-side. Surfaces B and B are electrically connected to the front and back via through holes.

However, in this case, as shown by the broken line in FIG. 7, one unit of each of the u, v, and w phases was deleted.
The sheet-shaped coil 35 can be formed shorter by 2 degrees ((18 degrees + 6 degrees) × 3 = 72 degrees). As a result, a clearance portion 55 is formed by an amount corresponding to 72 degrees. The power supply terminal portion 37 is arranged by utilizing the clearance 55.

In the case of FIG. 6, the power supply terminal portion 37 is formed so as to project to the lower side of the coil board 39, but in the case of FIG. 8, since there is a clearance 55, the coil board 39 is extended as it is. The power supply terminal portion 37 is formed.

In this way, the coil substrate 39 and the power feeding terminal portion 3 are
When the sheet-shaped coil 35 is formed linearly and the sheet-shaped coil 35 is attached to the outer peripheral surface of the yoke holder 31, the power supply terminal portion 37 cannot be led out to the outside (outer rotor rotor) as it is.

Therefore, as shown by the broken lines in FIGS. 8 and 9, the feeding terminal portion 37 is bent along the bending lines r and s. The feeding terminal portion 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 approximately 45 ° with respect to the coil substrate 39. As a result of this bending, the power supply terminal portion 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 tip end side of the bending line s is parallel to the chassis 11, the power supply terminal portion 37 can be led out to the outside of the outer rotor as desired as shown in FIG.

The outer peripheral surface of the yoke holder 31 corresponding to the power supply terminal portion 37 is cut so that the bent portion can be firmly adhered and fixed to the outer peripheral surface of the yoke holder 31 when the power supply terminal portion 37 is bent from the bending line r. A notched end face 60 as shown in FIG. 10 is formed.

Since the gap portion 55 has no field coil and does not form a magnetic circuit, it is not necessary to dispose the yoke 33 at a portion facing the gap portion 55. Therefore, the notch end surface 6 is provided with respect to the yoke holder 31 facing the clearance portion 55.
When 0 is formed, eddy current loss, which is a type of iron loss in the gap portion 55, does not occur. By reducing the eddy current loss, the motor current consumption is reduced and the motor drive efficiency is also improved.

The relationship between the number of poles 2p of the magnet 40 and the number of phases n of the sheet-shaped coil 35 described above is merely an example, and the integer value may be other than the above-mentioned numerical value, and deletion of each phase of the coil may be performed for each unit. If it is deleted, it can sufficiently function as a motor, so that the clearance portion created by this deletion can be effectively used.

[0062]

As described above, in the brushless motor according to the present invention, the outer rotor system is adopted as the radial flux type, and the hollow bottomed cylindrical body is used as the yoke holder arranged inside. A sheet coil is attached to the outer peripheral surface of the sheet coil.

According to this, since the sheet-shaped coil can be attached and fixed to the outer peripheral surface of the yoke holder, the vibration generated by the switching current for driving the motor supplied to the sheet coil can be effectively suppressed. Therefore, a brushless motor with less noise can be provided.

Since the magnet is arranged on the outer rotor side, the magnet can be easily magnetized, and a motor structure suitable for multi-pole and miniaturization can be provided.

Since the hollow bottomed cylindrical body is used as the yoke holder, a relatively large internal space can be formed in the yoke holder. Therefore, by utilizing this internal space, a circuit board, a circuit component, and other members related to the brushless motor drive can be attached here.

Therefore, it is not necessary to dispose a circuit board, circuit parts or other members on the outside of the brushless motor, and it is possible to achieve space saving when the brushless motor is incorporated into the apparatus.

Especially when high accuracy is required, a precision bearing mechanism can be easily arranged in the yoke holder in place of these circuit boards, so that a high-precision motor can be constructed without enlarging the motor itself. It has characteristics. Therefore, the present invention is extremely suitable when applied to a small headphone type tape recorder or the like that is sensitive to vibration.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a 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 type outer rotor type brushless motor according to the present invention.

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

FIG. 6 is a configuration diagram showing an example of a sheet-shaped coil used in a brushless motor.

FIG. 7 is another diagram showing the relative positional relationship between the magnet and the sheet coil.

FIG. 8 is a configuration diagram showing another example of the sheet-shaped coil used in the brushless motor.

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

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

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

[Explanation of symbols]

 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 Free space

Claims (1)

[Claims] 1. The relationship between the number of poles 2p of a cylindrical magnet attached to the outer rotor side and the number n of field coils attached to the stator-side yoke holder so as to face the magnet is 2p: n = 4. : 3 or 2p: n = 10: 6
The field coil uses a sheet-shaped coil formed of a coil conductor, and the yoke holder arranged inside is configured as a hollow bottomed cylindrical body. A radial type outer rotor type brushless motor characterized in that a circuit board and the like are internally provided in an internal space formed by the shaped body.