JP2000217331A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain microminiaturization by disposing a fist coil, a magnet, and a second coil in this order along the axial length of a motor. SOLUTION: A magnet 1 is formed into a hollow cylindrical shape and its outer surface is divided into (n) sections in a peripheral direction, thereby magnetizing them to different poles alternately. With a first coil 2 of the magnet 1 and a second coil 3 of the magnet 1 disposed successively along the axial direction of the magnet 1, the outer magnetic poles 18a, 18b and 19a, 19b and the inner magnetic poles 18c, 18d and 19c, 19d of the first and the second stators 18, 19 energized by the first and the second coils 2, 3 are placed so as to face the outer surface and the inner surface of the magnet 1. A lubricating washer 8 is disposed between the front end part of the first and the second inner magnetic poles 18c, 18d, and 19c, 19d and a rotor shaft 7. As a result, the size of a step motor is determined based on the diameter and the length of a magnet and a coil. It is thus possible to microminiaturize a step motor by reducing their sizes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical motor having a very small size.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional small cylindrical step motor. A stator coil 105 is wound around the bobbin 101 concentrically, and the bobbin 101 is sandwiched and fixed by two stator yokes 106 in the axial direction. The teeth 106a and 106b are alternately arranged, and a stator 103 is formed in the case 103 by fixing a stator yoke 106 integral with the stator teeth 106a or 106b.

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 119 includes a rotor magnet 111 fixed to a rotor shaft 110, and the rotor shaft 110 is rotatably supported between two bearings.

[0004]

However, the above-mentioned conventional small step motor has a case 10 on the outer periphery of the rotor.
3. Since the bobbin 101, the stator coil 105, the stator yoke 106 and the like are arranged concentrically, there is a disadvantage that the outer diameter of the motor becomes large. The magnetic flux generated by energizing the stator coil 105 is shown in FIG.
As shown in FIG.
Since it passes through a1 and the end face 106b1 of the stator teeth 106b and does not effectively act on the rotor magnet 111, there is a disadvantage that the output of the motor does not increase.

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

[0006]

In order to achieve the above object, the present invention relates to a magnet formed in a cylindrical shape and having at least its outer peripheral surface divided into n parts in the circumferential direction and alternately magnetized to different poles. And a rotor shaft fixed to the magnet, a first coil, the magnet, and a second coil arranged in order in the axial direction of the magnet, a first outer magnetic pole excited by the first coil, and The first inner magnetic pole is opposed to the outer peripheral surface and the inner peripheral surface of one end of the magnet, and the second outer magnetic pole and the second inner magnetic pole excited by the second coil are connected to the other end of the magnet. Washers having lubricity are arranged between the tip of the first inner magnetic pole and the rotor shaft and between the tip of the second inner magnetic pole and the rotor shaft so as to face the outer peripheral surface and the inner peripheral surface. It is, is to adopt a structure characterized in that for receiving the axial direction of the rotor axis washer having the lubricating property.

[0007] In the above configuration, 1) the diameter of the motor is first, which is opposed to the outer peripheral surface of the magnet.
The length in the axial direction of the motor is determined by the second outer magnetic pole, and is determined by arranging the first coil, the magnet, and the second coil in order, so that the motor can be reduced in size. The magnetic flux generated by the first coil works effectively because it traverses the magnet between the first outer magnetic pole and the first inner magnetic pole. The magnetic flux generated by the second coil crosses the magnet between the second outer magnetic pole and the first inner magnetic pole, thereby increasing the output of the motor. 2) A washer having lubricity is disposed between the tip of the first inner magnetic pole and the rotor shaft and between the tip of the second inner magnetic pole and the rotor shaft, and the washer receives the axial direction of the rotor shaft. Therefore, wear of the rotor shaft is minimized. Further, since the washer is made of a plastic substrate, the noise generated when the rotor rotates can be suppressed to a very small level.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 are views of a first embodiment of a stepping motor according to the present invention. FIG. 1 is an exploded perspective view of the stepping motor, and FIG. 2 is an axial sectional view after the stepping motor is assembled. FIG. 3 is a sectional view taken along line AA of FIG. 2 and a sectional view taken along line BB of FIG.

In FIGS. 1 to 3, reference numeral 1 denotes a cylindrical magnet constituting a rotor. The magnet 1, which is a rotor, has its outer peripheral surface divided into n parts in the circumferential direction (in this embodiment, divided into four parts). T) S-poles and N-poles are alternately magnetized to be magnetized portions 1a, 1b, 1c, and 1d.
c is magnetized to the S pole, and the magnetized portions 1b and 1d are magnetized to the N pole. Reference numeral 7 denotes a rotor shaft, and the rotor shaft 7 is fixed to the magnet 1, which is a rotor. The rotor shaft 7 and the magnet 1 constitute a rotor.

Reference numerals 2 and 3 denote cylindrical coils. The coils 2 and 3 are arranged coaxially with the magnet 1 and at a position sandwiching the magnet 1 in the axial direction. The dimensions are almost the same as the outer diameter of the magnet 1.

Reference numerals 18 and 19 denote a first stator and a second stator.
, The first stator 18 and the stator 1
9 are arranged 180 / n degrees, ie, 45 degrees apart,
These first stators 18 and 19 are composed of an outer cylinder and an inner cylinder. The coil 2 is provided between the outer cylinder and the inner cylinder of the first stator 18, and when the coil 2 is energized, the first stator 18 is excited. The outer cylinder and the inner cylinder of the first stator 18 have the outer magnetic poles 18a at their distal ends.
18b and the inner magnetic poles 18c and 18d are formed. The inner magnetic pole 18c and the inner magnetic pole 18d are formed so as to be in phase with each other by 360 / (n / 2) degrees, that is, 180 degrees. Outer magnetic pole 18a with respect to 18c
Are arranged to face each other, and the outer magnetic pole 18b is arranged to face the inner magnetic pole 18d.

Outer magnetic poles 18a, 1 of the first stator 18
8 b and the inner magnetic poles 18 c and 18 d are provided so as to sandwich one end of the magnet 1 so as to face the outer peripheral surface and the inner peripheral surface on one end side of the magnet 1.

The coil 3 is provided between the outer cylinder and the inner cylinder of the second stator 19, and when the coil 3 is energized, the second stator 19 is excited. The outer cylinder and the inner cylinder of the second stator 19 have outer poles 19a,
9b and inner magnetic poles 19c and 19d are formed, and the phases of the inner magnetic pole 19c and the inner magnetic pole 19d are formed so as to be in phase with each other by 360 / (n / 2) degrees, that is, 180 degrees. The outer magnetic pole 19a is opposed to the inner magnetic pole 19d, and the outer magnetic pole 19b is opposed to the inner magnetic pole 19d.

The outer magnetic poles 19a, 1a of the second stator 19,
The magnet 9 b and the inner magnetic poles 19 c and 19 d are provided so as to face the outer peripheral surface and the inner peripheral surface on the other end side of the magnet 1 so as to sandwich the other end of the magnet 1.

Accordingly, the magnetic flux generated by the coil 2 crosses the magnet 1 which is a rotor between the outer magnetic poles 18a and 18b and the inner magnetic poles 18c and 18d, and thus effectively acts on the magnet 1 which is a rotor. The generated magnetic flux is generated by the outer magnetic poles 19a and 19b and the inner magnetic pole 19
Acts on the magnet 1 which is a rotor between c and 19d to increase the output of the motor.

Further, the relative rotational positions of the first stator 18 and the second stator 19 are made exactly the same, and the magnetized portion of the magnet 1 sandwiched between the outer magnetic pole and the inner magnetic pole of the first stator is magnetized. The phase and the magnetization phase of the magnetized portion of the magnet 1 sandwiched between the outer magnetic pole and the inner magnetic pole of the second stator may be shifted by (180 / n) degrees, that is, 45 degrees.

Reference numeral 20 denotes a holding member as a cylindrical member made of a non-magnetic material. Grooves 20a and 20b are provided on one end surface inside the holding member 20, and a groove 20a is provided on the other end.
grooves 20c, 2a whose phases are shifted by 45 degrees with respect to
0d is provided.

The outer magnetic poles 18a and 18b of the first stator 18 are fitted into the grooves 20a and 20b, and the outer magnetic poles 19a and 19b of the second stator 19 are fitted into the grooves 20c and 20d. Are fixed with an adhesive, and the first stator 18 and the second stator 19 are attached to the holding member 20.

The first stator 18 and the second stator 19 are connected to the outer magnetic poles 18a and 18b and the inner magnetic pole 1 respectively.
8c, 18d, outer magnetic poles 19a, 19b and inner magnetic pole 1
9c and 19d are opposed to each other, and are fixed at a certain distance by protrusions 20e and 20f on the inner surface side of the holding member 20.

Between the tip portions 18c and 18d of the first inner magnetic pole and the rotor shaft 7, and between the tip portions 19c and 19c of the second inner magnetic pole.
A washer 8 having lubricity is disposed between the rotor shaft 9d and the rotor shaft 7, and the washer 8 receives the axial direction of the rotor shaft. At this time, the rotor shaft and the hole 18 of the first stator 18 are
e and a gap is provided so that the hole 19e of the second stator 19 does not contact. As the base material of the washer having lubricity, the rotor shaft is made of a metal such as stainless steel or phosphor bronze because the rigidity is required. Therefore, a plastic material having small abrasion noise and impact noise when the rotor shaft rotates is selected.

As the plastic base material, nylon,
It is preferable to use Teflon, polyacetal, or polyamideimide. That is, since they are excellent in self-lubricating properties and have a small coefficient of friction, they reduce abrasion noise and impact noise and also have better abrasion resistance.

Further, when a small amount of graphite particles or molybdenum disulfide having excellent lubricity is added to nylon, abrasion resistance is improved. Thus, lubricating particles such as graphite and molybdenum disulfide may be added to the plastic depending on the situation.

FIG. 2 is a cross-sectional view of the step motor. FIGS. 3A, 3B, 3C, and 3D are cross-sectional views taken along line AA in FIG. ), (F), (g), (h)
Shows a cross-sectional view along the line BB in FIG. FIG. 3 (a)
3 (e) is a cross-sectional view at the same time, FIGS. 3 (b) and 3 (f) are cross-sectional views at the same time, and FIGS. 3 (c) and 3 (g) are the same. 3D and FIG. 3H are cross-sectional views at the same time. Next, the operation of the step motor of the present invention will be described.

From the state shown in FIGS. 3A and 3E, the coil 2
, 3 and the outer magnetic pole 18 of the first stator 18.
When a and 18b are N poles, the inner magnetic poles 18c and 18d are S poles, the outer magnetic poles 19a and 19b of the second stator 19 are N poles, and the inner magnetic poles 19c and 19d are S poles. 1 rotates 45 degrees in the counterclockwise direction, and becomes a state shown in FIGS.

Next, the power supply to the coil 2 is reversed, and the first
The outer magnetic poles 18a and 18b of the stator 18 are S poles,
The inner stator poles 18c and 18d are set to the N pole, and the second stator 1
9, the outer magnetic poles 19a and 19b are S-poles, and the inner magnetic poles 19a and 19b are
When the magnets c and 19d are excited with the N pole, the magnet 1, which is the rotor, further rotates counterclockwise by 45 degrees to reach the state shown in FIGS. Thereafter, by sequentially switching the energizing direction to the coils 2 and 3 in this manner, the magnet 1, which is a rotor, rotates to a position corresponding to the energizing phase.

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 hollow cylindrical shape. Second, the outer peripheral surface of the magnet is divided into n portions in the circumferential direction and magnetized alternately at different poles. Third, the first coil, the magnet, and the second coil are arranged in order in the axial direction of the magnet. Fourth, the first and second coils excited by the first and second coils The outer magnetic pole and the inner magnetic pole of the second stator are opposed to the outer peripheral surface and the inner peripheral surface of the magnet. Fifth, lubricating properties are provided between the tip portions of the first and second inner magnetic poles and the rotor shaft. Disposing a washer having the same.

Therefore, the diameter of the step motor only needs to be large enough to provide the diameter of the magnet in the direction of the magnetic pole of the stator, and the axial length of the step motor is equal to the length of the magnet. It suffices if the length is just the sum of the lengths of the first coil and the second coil. For this reason, the size of the step motor is determined by the diameters and lengths of the magnet and the coil. If the lengths of the magnet and the coil are reduced, the step motor can be miniaturized. Further, by providing a washer having lubricity between the tips of the first and second inner magnetic poles and the rotor shaft and receiving the rotor shaft in the axial direction, a stable rotational torque can be obtained even when used for a long time. In addition, the friction noise generated when the rotor shaft rotates can be suppressed to be small, so that an ultra-small step motor can be provided.

If the diameters and lengths of the magnet and the coil are extremely small, it is difficult to maintain the accuracy of the step motor. However, this is because the hollow of the magnet is formed in a cylindrical shape, and the hollow cylinder is formed. The problem of accuracy as a step motor is solved by a simple structure in which the outer and inner magnetic poles of the first and second stators face the outer and inner peripheral surfaces of the formed magnet. At this time, if not only the outer peripheral surface of the magnet but also the inner peripheral surface of the magnet are magnetized in a circular direction, the output of the motor can be more effectively increased.

[0029]

As described above, according to the present invention, a magnet formed into a cylindrical shape and having at least its outer peripheral surface divided by n in the circumferential direction and alternately magnetized to different poles and fixed to the magnet A first coil, the magnet, and a second coil arranged in this order in the axial direction of the magnet, and a first outer magnetic pole and a first inner magnetic pole excited by the first coil. And a second outer magnetic pole and a second inner magnetic pole excited by the second coil are connected to the other end of the magnet. Washers having lubricity are disposed between the tip of the first inner magnetic pole and the rotor shaft and between the tip of the second inner magnetic pole and the rotor shaft, respectively, so as to face the outer peripheral surface and the inner peripheral surface of the rotor. Sa Since the structure is characterized by receiving the axial direction of the rotor shaft with the washer having lubricity, a motor having a completely new configuration different from the conventional one can be obtained. This is the optimal configuration. The magnet is formed in a hollow cylindrical shape, and the first and second outer magnetic poles and the inner magnetic pole are opposed to the outer peripheral surface and the inner peripheral surface of the hollow cylindrical magnet. Can be obtained.

Furthermore, lubricative washers are arranged between the tip of the first inner magnetic pole and the rotor shaft and between the tip of the second inner magnetic pole and the rotor shaft, respectively. Since the rotor receives the axial direction, it is possible to provide an ultra-small step motor capable of obtaining a stable rotational torque even when used for a long time with a minimum of noise generated when the rotor rotates.

[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 rotor rotating operation of the step motor shown in FIG. 2;

FIG. 4 is a sectional view of a conventional small cylindrical step motor.

FIG. 5 is a diagram for illustrating a state of a magnetic flux generated by energizing a stator coil in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 magnet 1a, 1c S pole 1b, 1d N pole 2 first coil 3 second coil 7 rotor shaft 7a rotor shaft surface 8 lubrication washer 18 first stator 18a, 18b outer magnetic pole 18c, 18d inner magnetic pole 18e rotor shaft 7 through hole 19 second stator 19a, 19b outer magnetic pole 19c, 19d inner magnetic pole 19e through hole of rotor shaft 7 holding member 20a, 20b insertion groove of outer magnetic pole 18a, 18b 20c, 20d insertion of outer magnetic pole 19a, 19b Grooves 20e, 20f Protrusions on the inner surface side of holding member 20 101 Bobbin 102 Stator 103 Case 105 Stator coil 106 Stator yokes 106a, 106b Stator teeth 108 Bearing 109 Rotor 110 Rotor shaft 111 Rotor magnet 115 Flange

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H605 AA07 BB05 BB16 BB18 BB19 CC03 CC04 DD01 DD05 EA02 EA06 EA07 EB05 EB06 EB16 FF00 FF06 5H621 GA02 GA05 GA10 GB10 GB11 HH01 JK02 JK05 JK07 JK17 JK19 PP03

Claims (4)

[Claims] A magnet formed in a cylindrical shape and having at least its outer peripheral surface divided into n portions in the circumferential direction and alternately magnetized to different poles, and a rotor shaft fixed to the magnet, wherein the shaft of the magnet is provided. A first coil, the magnet, and a second coil are sequentially arranged in a direction, and a first outer magnetic pole and a first inner magnetic pole excited by the first coil are connected to an outer circumferential surface and an inner circumferential surface of one end of the magnet. A second surface that is excited by the second coil
The outer magnetic pole and the second inner magnetic pole are opposed to the outer peripheral surface and the inner peripheral surface on the other end side of the magnet, and between the tip of the first inner magnetic pole and the rotor shaft and the second inner magnetic pole. A motor, wherein a washer having lubricity is disposed between a tip portion and the rotor shaft, and the washer having lubrication receives an axial direction of the rotor shaft. 2. The motor according to claim 1, wherein a base material of the washer having lubricity is plastic. 3. The motor according to claim 1, wherein the plastic is selected from nylon, Teflon, polyacetal, and polyamideimide. 4. The motor according to claim 1, wherein at least one kind of particles of graphite or molybdenum disulfide is added to said plastic.