JP2000253642A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a stepping motor and attain high output by disposing a coil on a magnet of which a disc-shaped board surface is divided into (n) circumferentially and different poles are polarized alternately so as to be concentric with the magnet, and facing the first and second pole boards each other, each of which has the specific number of poles, so as to sandwich the magnet. SOLUTION: The board surface of a disc-shaped magnet 1 is divided into (n) circumferentially, the south pole and north pole are polarized alternately, and an output shaft 13 is pressed into a fitting part 1w for forming a rotor. A cylindrical coil 7 is disposed so as to be concentric with the magnet 1, the first and second pole boards 3, 4, each of which has the number of n/2 poles are fixed to a pole board connecting member 9 and disposed at a position so as to sandwich the magnet 1 and face each other for forming a stator. It is thus possible to decrease the axial thickness of the step motor for miniaturization, and make magnetic flux generated from the coil 7 act on the magnet 1 effectively for an increase in output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and inexpensive PM step motor having a flat cylindrical shape.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional small cylindrical step motor. A stator coil 105 is wound concentrically around the bobbin 101, and the bobbin 101 is sandwiched and fixed in the axial direction by two stator yokes 106. 106a and 106b are arranged alternately, and the case 103 has stator teeth 106a and 10b.
The stator 102 is configured by fixing a stator yoke 106 integral with the stator yoke 6b.

One of two cases 103 has a flange 1
15 and the bearing 108 are fixed, and another bearing 108 is fixed to the other case 103. The rotor 109 includes a rotor magnet 111 fixed to a rotor shaft 110, and the rotor magnet 111 forms a radial gap with the stator yoke 106a of the stator 102. And
The rotor bearing 110 is rotatably supported between the two bearings 108.

[0004]

However, the above-mentioned conventional small stepping motor has a drawback that the rotor magnet 111 must be lengthened due to the necessity of obtaining a large torque, and the length is increased in the axial direction. Also, the stator coil 105
As shown in FIG. 9, the magnetic flux generated by energization of the stator teeth 106a1 and the end face 106a1 of the stator teeth 106a
06b and the end face 106b1 of the rotor magnet 1
There is a disadvantage that the output of the motor does not increase without effectively acting on the motor.

Accordingly, a first object of the present invention is to provide a micro motor having a novel configuration.

A second object of the present invention is to facilitate the manufacture of a motor.

A third object of the present invention is to provide a compact and efficient motor having a high driving force.

[0008]

In order to achieve the above object, the present invention provides a coil and a disk, which is formed in a disk shape and at least the disk surface is divided into n parts in the circumferential direction and alternately magnetized to different poles. The magnet is arranged so that the central axes of the coil and the magnet coincide with each other, and n / 2 first magnetic poles excited by the coil are opposed to one surface of the magnet and excited by the coil. n
A motor characterized in that / 2 second magnetic poles are opposed to the other side of the magnet.

In the above construction, the axial thickness of the parts constituting the basic motor is determined by the thickness of the magnet and the first and second parts.
The diameter of the motor is determined by the diameter of the magnet and the diameter of the coil, so that the motor can be extremely reduced in size. Further, the magnetic flux generated by the coil crosses the magnet between the first magnetic pole and the second magnetic pole, so that the magnetic flux effectively acts on the magnet as the rotor and increases the output of the motor.

[0010]

(Embodiment 1) FIGS. 1 to 3 show Embodiment 1 of the present invention.
FIG. 1 is an exploded perspective view of the step motor, FIG. 2 is an axial cross-sectional view after assembling the step motor, and FIG. FIG. 3 is a diagram viewed from a direction A of FIG.

In FIG. 1 to FIG. 3, reference numeral 1 denotes a disk-shaped magnet constituting a rotor. The magnet 1, which is a rotor, has its disk surface divided into n parts in the circumferential direction. (N = 8)], the S pole and the N pole are magnetized alternately, and the direction of the magnetization is perpendicular to the board surface. Magnetized parts 1a, 1b, 1c, 1d, 1e, 1f, 1
g, 1h, the magnetized parts 1a, 1
c, 1e, and 1g are magnetized to the S pole, and the magnetized portions 1b, 1d,
1f, 1h are magnetized to the N pole, and when viewed from the back surface, the magnetized portions 1a, 1c, 1e, 1g are magnetized to the N pole,
The magnetized portions 1b, 1d, 1f, 1h are magnetized to S poles. The magnet 1 is made of a plastic magnet material formed by injection molding. Thereby, the thickness of the disk shape can be made very thin. Further, the magnet 1 is provided with a fitting portion 1w having a small inner diameter at a central portion in the axial direction.

Reference numeral 13 denotes an output shaft serving as a rotor shaft. The output shaft 13 is fixed to the fitting portion 1w of the magnet 1 serving as a rotor by press fitting. Since the magnet 1 is made of a plastic magnet formed by injection molding, it does not crack even when it is assembled by press-fitting, and is easy to manufacture even with a complicated shape having a fitting portion 1w having a small inner diameter at the center in the axial direction. Becomes Further, since the output shaft 13 and the magnet 1 are assembled and fixed by press-fitting, it is easy to assemble and can be manufactured at low cost. The output shaft 13 and the magnet 1 constitute a rotor.

Reference numeral 7 denotes a cylindrical coil whose inner diameter is slightly larger than the outer diameter of the magnet 1.
The coil 7 is arranged on the same plane as the disk surface of the magnet 1 and concentrically outside the magnet 1 via a gap.

Reference numerals 3, 4 and 9 denote stator constituent members made of a soft magnetic material constituting the stator. Reference numeral 3 denotes n / 2 first magnetic poles 3a, 3b, 3c, and 3d extending in the center axis direction at a period of 720 / n degrees, that is, 90 degrees in the thin plate ring 3w.
This is a first magnetic pole substrate having a shape provided with. Reference numeral 4 denotes n / 2 second magnetic poles 4a, 4b, 4c, and 4d extending in the central axis direction at a period of 720 / n degrees, that is, 90 degrees on the thin plate ring 4w.
Is a second magnetic pole substrate having a shape provided with. Reference numeral 9 denotes a pole board connecting member for connecting the pole board 3 and the pole board 4. The pole substrate connecting member 9 fits or adheres to the substrate 3 at the recess 9w, and fits or adheres to the substrate 4 at 9v.
This constitutes a stator. At this time, the first
Magnetic poles 3a, 3b, 3c, 3d and second magnetic poles 4a, 4a
b, 4c, and 4d are arranged and fitted or bonded so that the phases are the same. Further, the coil 7 and the magnet 1 are arranged between the first magnetic pole substrate 3 and the second magnetic pole substrate 4, and especially the magnet is arranged with a certain gap.

With this configuration, the magnetic pole can be formed while minimizing the axial thickness of the motor. That is, n /
The two first magnetic poles are all made of thin plates lying in the same plane, and the n / 2 second magnetic poles are all made of thin sheets lying in the same plane. , Forming a stator. If the magnetic pole is formed by the unevenness extending in the axial direction, the thickness (length in the axial direction) of the motor is increased by that amount, but in the present embodiment, the magnetic pole is constituted by teeth in a plane perpendicular to the axis. Therefore, the thickness of the motor can be minimized.

When the coil 7 is energized, the first magnetic poles 3a, 3b, 3c, 3d and the second magnetic pole 4
a, 4b, 4c, 4d are excited to opposite poles. Therefore, the magnetic flux generated by the coil 7 is the first magnetic pole 3a,
3b, 3c, 3d and second magnetic poles 4a, 4b, 4c, 4
Since it crosses the magnet 1 which is a rotor between the magnets d, it effectively acts on the magnet which is a rotor and increases the output of the motor.

Reference numeral 11 denotes a first bearing substrate which is made of a non-magnetic material, has the same outer diameter as the pole substrate connecting member 9, and has a bearing hole 11g having a small inner diameter at the center thereof. The first bearing substrate 11 is tightly adhered to the side surface of the first magnetic pole substrate 3 and one end of the output shaft 13 is rotatably fitted in the hole 11g.

Reference numeral 12 denotes a second bearing substrate which is made of a non-magnetic material, has the same outer diameter as the pole substrate connecting member 9, and has a bearing hole 12g having a small inner diameter at the center thereof. The second bearing substrate 12 is tightly adhered to the side surface of the second magnetic pole substrate 4, and the other end of the output shaft 13 is rotatably fitted in the hole 12g.

Since the first bearing substrate 11 is made of a non-magnetic material, the first magnetic poles 3a, 3b, 3c, 3d
Work effectively as magnetic poles, and the second bearing substrate 12 is made of a non-magnetic material, so that the second magnetic poles 4a, 4a
b, 4c and 4d work effectively as magnetic poles, and the motor obtains a high output. In addition, the first bearing substrate 1 described here
The functions of the first and second bearing substrates 12 are in the bearings, and the shapes themselves have no function.

FIG. 2 is a side view of the stepping motor, and FIGS. 3A and 3B show poles 1a, 1b, 1c, 1d, 1e, 1f, 1g, and 1h of the magnet 1 as the motor rotates. 2 shows the states of the two magnetic poles 4a, 4b, 4c, and 4d, in which the second bearing substrate 12 is omitted from the direction A in FIG.

Next, the operation of the step motor will be described. The coil 7 is energized from the state shown in FIG.
a, 4b, 4c, 4d are S poles, first magnetic poles 3a, 3b,
When the magnets 3c and 3d are excited to the N pole, the magnet 1, which is a rotor, rotates 45 degrees counterclockwise to reach a state shown in FIG.

Next, the energization of the coil 7 is reversed so that the second magnetic poles 4a, 4b, 4c, 4d are changed to the N pole, the first magnetic poles 3a,
When the magnets 3b, 3c, and 3d are excited to the S pole, the magnet 1, which is a rotor, further rotates 45 degrees in a counterclockwise direction.
The state returns to the state shown in FIG. Thereafter, by sequentially switching the energizing direction to the coil 7 in this manner, the magnet 1 serving as the rotor rotates to a position corresponding to the energizing phase.

The rotation direction of the rotor of the present motor is determined by the initial position of the rotor and the direction of current supply to the first coil 7. It is easily understood by those skilled in the art that the rotation in a fixed direction can be easily dealt with by a method such as providing a Hall element or the like near the magnet of the rotor and detecting the position of the rotor to control the direction of energization to the coil 7. I understand. Here, a description will be given of the fact that the step motor having such a configuration is the most suitable configuration for miniaturizing the motor.

The basic configuration of the step motor is as follows. First, the magnet is formed in a disk shape.
Secondly, the magnet is divided into n portions in the circumferential direction in the direction perpendicular to the surface and alternately magnetized to different poles. Third, the coil is arranged on the same plane as the surface of the magnet. Fourth, the plate-shaped magnetic poles are arranged parallel to the surface of the magnet, and fifth, the magnetic poles excited by the coil are arranged so as to sandwich the magnet in the axial direction. is there.

When the present motor is incorporated in a device, the first bearing substrate 11 and the second bearing substrate 12 can be replaced by their chassis or the like, so that a basic axial direction for driving the step motor is considered. Is the thickness of the magnet and the thickness of the first and second magnetic poles plus a gap, and the diameter of the motor is determined by the diameters of the magnet and the coil and the thickness of the magnetic pole board connecting member 9. If the diameter and the thickness are made very small, the step motor can be made very small.

(Embodiment 2) FIG. 4 is a view showing a stepping motor according to Embodiment 2 of the present invention. In the first embodiment, the coil 3
Are arranged concentrically with the magnet 1 and outside the magnet 1 via a gap. However, according to the inventors' research,
Of the magnetic flux generated by the coil 7, the magnetic flux flowing from the first magnetic pole substrate 3 to the second magnetic pole substrate 4 across the coil 7 is:
Since it does not cross the magnet 1, it does not contribute to the rotational force. The present magnetic flux was found to be a useless magnetic flux that increased the inductance of the coil, thereby generating a back electromotive force in a high-speed region of the rotor, and causing a decrease in output.

Therefore, in the present embodiment, the coil is formed in a disk shape having substantially the same outer diameter as the magnet of the rotor in the first embodiment, and is formed between the magnet and the first magnetic pole or between the magnet and the second magnetic pole. It is arranged and arranged between them.

FIG. 4 is a sectional view in the axial direction after the assembling of the step motor, and the reference numerals are the same as those described with reference to FIG. 2 of the first embodiment. In contrast to the first embodiment, the coil 7
Has a disk shape having substantially the same outer diameter as the magnet of the rotor, and is disposed between the magnet 1 and the second magnetic pole substrate 4 with a gap therebetween.

Further, the second magnetic poles 4a, 4b, 4c, 4d
The tip is made thicker in the axial direction so that the tip is opposed to the magnet 1 with a gap having the same length as that of the first embodiment.

The shape and configuration of the other members are the same as those of the first embodiment.
The operation principle is the same as that described with reference to FIG. With this configuration, of the magnetic flux generated by the coil 7 described at the beginning of this embodiment, the first magnetic pole substrate 3
As a result, the useless magnetic flux flowing to the second magnetic pole substrate 4 across the coil 7 is drastically reduced, and a motor having a large rotational force can be obtained even in a high-speed rotation range. Further, in the present motor, almost all of the magnetic flux generated by the coil 7 crosses the magnet 1, so that the output per unit current increases, and the motor is extremely efficient.

(Embodiment 3) FIGS. 5 to 7 show a stepping motor according to Embodiment 3 of the present invention. In Example 1 and Example 2, the rotor was constituted by one magnet and coil, and two magnetic pole substrates sandwiching them. However, there is a limit to the torque that can be obtained only by the above configuration. Further, as described in the first embodiment, in order to obtain an arbitrary rotation direction by the above-described motor, a rotor position detecting unit using a Hall element or the like is required.

Therefore, in this embodiment, one motor is constructed by arranging a plurality of motors each including the coil, magnet, first magnetic pole, and second magnetic pole described in the first embodiment in the axial direction.

FIG. 5 is an exploded perspective view of a step motor, and FIG.
7 is an axial cross-sectional view after assembling the step motor, FIG.
FIG. 7 is a view of a part of the motor viewed from a direction A in FIG. In the figure, a magnet 1, a first magnetic pole substrate 3, a second magnetic pole substrate 4, a coil 7, and a magnetic pole substrate connecting member 9 which are rotors are the same as those in the first embodiment. I have. On the other hand, 2 is a magnet which is a rotor, 5 is a first magnetic pole substrate, 6 is a second magnetic pole substrate, 8 is a coil, and 10 is a magnetic pole board connecting member. , 7, and 9 are formed of the same material and form the rotating portion B.

The output shaft 13 serving as the rotor shaft is fixed by press-fitting to the fitting portions 1w and 2w where the inner diameters of the magnets 1 and 2 serving as the rotor in the axial center are reduced. Further, the rotating part A and the rotating part B are fixed by bonding the second magnetic pole substrate 4 of the rotating part A and the first magnetic pole substrate 5 of the rotating part B. Further, the first described in the first embodiment
Of the output shaft 13 is rotatably fitted in the hole 11g, and the second bearing substrate 12 is rotated. The portion B is closely adhered to the side surface of the second magnetic pole substrate 6, and the other end of the output shaft 13 is rotatably fitted in the hole 12g.

At this time, the magnetic poles 3a, 3b, 3c, 3d of the first magnetic pole substrate 3 of the rotating portion A and the second magnetic pole substrate 4
Of the magnetic poles 4a, 4b, 4c, 4d of the first magnetic pole substrate 5 of the rotating portion B and the magnetic poles 6a, 6b, 6c, 6d of the second magnetic pole substrate 6 in the rotation direction. All relationships are in phase.

As is clear from the above description, the output shaft 13 obtains an output of a size obtained by combining the rotating parts A and B, that is, twice the output of the motor of the first embodiment.
The output of the motor obtained by bonding the rotating part A and the rotating part B described in the present embodiment is larger than the output of the motor obtained by increasing only the thickness of the rotating part A to the same thickness. That is, in this motor, by increasing the thickness of the rotor magnet 1, the first magnetic pole substrate 3, and the second magnetic pole substrate 4, the thickness of the rotating portion A is comparable to the combined thickness of the rotating portion A and the rotating portion B in FIG. Since the area of the portion where the rotor magnet faces the magnetic pole can be increased as compared with the motor configured to perform the above operation, a motor having a larger output can be provided.

FIG. 7 is a side view of the step motor. 7A, 7B, 7C, and 7D show the poles 1a, 1b, and 1 of the magnet 1 accompanying the rotation of the motor in the rotating unit A.
c, 1d, 1e, 1f, 1g, and 1h and the states of the second magnetic poles 4a, 4b, 4c, and 4d of the rotating portion A are displayed. The rotating portion B is omitted from the direction A in FIG. Is displayed. 7 (e), (f), (g),
(H) shows the poles 2 a, 2 b, 2 c, 2 d, 2 e, 2 f, 2 g of the magnet 2 accompanied by the rotation of the motor in the rotating section B.
2h and the state of the poles of the second magnetic poles 6a, 6b, 6c and 6d of the rotating part B are displayed by omitting the second bearing substrate 12 from the direction A in FIG. FIGS. 7A and 7E are side views at the same point, and FIGS. 7B and 7F are side views at the same point.
(C) and (g) are side views at the same time, and FIG.
And (h) are side views at the same time.

Next, the operation of the step motor will be described. 7 (a) and 7 (e), the coils 7 and 8 are energized, and the second magnetic poles 4a, 4b, 4c,
And the first magnetic poles 3a, 3a of the rotating portion A (not shown).
b, 3c and 3d are N poles, and the second magnetic pole 6
When the first magnetic poles 5a, 5b, 5c, and 5d of the rotating part B (not shown) are excited to the S poles, the magnets 1 and 2 are rotors.
Rotates 22.5 degrees counterclockwise, and FIG. 7B and FIG.
The state shown in is shown.

Next, the energization of the coil 8 is reversed so that the first magnetic poles 3a, 3b, 3c, 3d of the rotating part A are S poles, and the second magnetic poles 6a, 6b, 6c,
6d is an N pole, and the second magnetic poles 6a, 6b, 6
When the first magnetic poles 5a, 5b, 5c, and 5d of the rotating portion B (not shown) are excited to the N pole, the magnets 1 and 2 as the rotors are further rotated counterclockwise. After rotating by 5 degrees, the state shown in FIGS. 7C and 7G is obtained.

Next, the energization of the coil 7 is reversed, and the second magnetic poles 4a, 4b, 4c, 4d of the rotating part A are set to the N pole, and the first magnetic poles 3a, 3b, 3c,
3d is an S pole, and the second magnetic poles 6a, 6b, 6
When the first magnetic poles 5a, 5b, 5c, and 5d of the rotating portion B (not shown) are excited to the N pole, the magnets 1 and 2 as the rotors are further rotated counterclockwise. After rotating by 5 degrees, the state shown in FIGS. 7D and 7H is obtained.

Thereafter, by sequentially switching the energizing direction to the coils 7 and 8 in this manner, the magnets 1 and 2 as rotors rotate to positions corresponding to the energizing phases.

In the above description with reference to FIG. 7, the description has been made of changing the current flowing through the coils while detecting the rotation angle of the rotor. The motor rotates without detecting the rotation angle of the rotor. Further, as is apparent from the present description, the rotation direction of the motor of this embodiment is
Therefore, the means for detecting the position of the rotor such as the Hall element described in the first embodiment is unnecessary.

[0043]

As described above in detail, according to the present invention,
A coil, comprising a magnet formed in a disk shape and having at least the board surface divided into n portions in the circumferential direction and alternately magnetized to different poles, and disposed so that the center axes of the coil and the magnet coincide with each other. N excited by the coil
/ 2 first magnetic poles are opposed to one side of the magnet, and n / 2 second magnetic poles excited by the same coil are opposed to the other side of the magnet. A completely different configuration of the motor can be obtained, which is the most suitable configuration for miniaturizing the motor.

Further, the n / 2 first magnetic poles are arranged at regular intervals in the circumferential direction of the magnet, the n / 2 second magnetic poles are arranged at regular intervals in the circumferential direction of the magnet, and 1
And the second magnetic pole are opposed to each other with the magnet interposed therebetween, so that an effective output can be obtained as a motor.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a step motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the step motor shown in FIG. 1 in an assembled state.

FIG. 3 is an explanatory diagram of a rotation operation of a rotor of the step motor shown in FIG. 1;

FIG. 4 is a sectional view of a step motor according to a second embodiment of the present invention in an assembled state.

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

FIG. 6 is a sectional view of the step motor shown in FIG. 5 in an assembled state.

FIG. 7 is an explanatory diagram of a rotation operation of a rotor of the step motor shown in FIG. 5;

FIG. 8 is a sectional view of a conventional step motor.

FIG. 9 is a sectional view showing a state of a conventional step motor.

[Explanation of symbols]

1, 2 magnet 3-6 magnetic pole substrate 3a, 3b, 3c, 3d, 4a, 4b, 4c, 4d, 5
a, 5b, 5c, 5d, 6a, 6b, 6c, 6d: magnetic poles 7, 8 coils 9, 10 magnetic pole board connecting members 11, 12 bearing board 13 output shaft

Claims (8)

[Claims] 1. A coil, comprising: a magnet formed in a disk shape and having at least the board surface divided into n portions in the circumferential direction and alternately magnetized to different poles, so that the center axes of the coil and the magnet coincide with each other. And the n / 2 first magnetic poles excited by the coil are opposed to one side of the magnet, and the n / 2 second magnetic poles excited by the coil are connected to the other side of the magnet. A motor characterized by being opposed to one side. 2. The n / 2 first poles are all configured as part of a thin pole substrate that is in the same plane, and the n / 2 second poles are all in the same plane. 2. The motor according to claim 1, wherein the stator is constituted by a magnetic pole substrate having a first magnetic pole and a magnetic pole substrate having a second magnetic pole. 3. The magnetic pole substrate according to claim 1, wherein the first magnetic pole and the second magnetic pole are connected to each other.
All the magnetic poles have a shape extending from the outer periphery in the direction of the central axis, and the magnetic pole substrate is connected by a magnetic pole substrate connecting member located on the outer peripheral side of the coil and the magnet. 2. The motor according to 1. 4. The n / 2 first magnetic poles are arranged at regular intervals in the circumferential direction of the magnet, the n / 2 second magnetic poles are arranged at regular intervals in the circumferential direction of the magnet, and The motor according to claim 1, wherein the first magnetic pole and the second magnetic pole are located at positions facing each other with the magnet interposed therebetween. 5. The motor according to claim 1, wherein the inner diameter of the coil is larger than the outer diameter of the magnet, and the coil is disposed outside the outer periphery of the magnet on the same plane as the disk surface of the magnet. . 6. A coil according to claim 1, wherein said coil has a disk shape having substantially the same outer diameter as a magnet of a rotor, and is disposed between said magnet and a first magnetic pole or between a magnet and a second magnetic pole. Item 2. The motor according to Item 1. 7. A motor comprising a plurality of motors each comprising the coil, the magnet, the first magnetic pole and the second magnetic pole according to claim 1, arranged in the axial direction. 8. The motor according to claim 7, wherein the phase of the pole of one magnet is shifted by 180 / n degrees in the circumferential direction with respect to the phase of the pole of an adjacent magnet. .