JP3103895B2 - 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 motor having a good rotation balance and capable of easily detecting one rotation or a fraction of a rotation of a rotor.

[0002]

2. Description of the Related Art For example, a video tape recorder (VTR)
2. Description of the Related Art In a motor for driving a precision machine such as the one described above, one rotation or a fraction of a rotation of a rotor may be accurately detected, and the detection signal may be used as a pulse signal to control the precision machine. As a motor provided with means for detecting the rotation of the rotor, there is a motor 1 as shown in FIG. FIG.
As shown in FIG. 1, in this motor 1, a PG magnet 4 for detection is attached to a part of the outer periphery of a rotor 2 in which a magnet 3 disposed opposite to a stator substrate 5 is mounted. A Hall element 6 is provided on the outer peripheral side of 2. In order to detect one or several rotations of the rotor, when the detection magnet 4 rotates together with the rotor 2, a change in magnetic flux is detected by a Hall element 6 arranged on the outer periphery of the rotor 2 and the magnet 4 By detecting passage through the vicinity of the element 6, one rotation or a fraction of a rotation of the rotor is detected.

However, in such a motor 1, since the detecting magnet 4 is attached to a part of the rotor 2, the rotational balance of the rotor may be deteriorated, and the operation of adjusting the rotational balance of the rotor becomes complicated. . Further, in such a motor 1, since the Hall element 6 needs to be arranged on the outer periphery of the rotor, the outer diameter of the entire motor in the radial direction becomes large, which is against the demand for downsizing the motor.

[0004]

In order to solve such inconvenience, a motor 1a as shown in FIG. 7 is conceptually conceivable. In this motor 1a, an inner projection 8 is provided on a part of the inner peripheral side of a ring-shaped plate magnet 3a disposed inside the rotor 2a, and the projection 8 passes through the stator substrate 5 when the rotor 3a rotates. The rotation detection coil 7 is installed on the surface of the. According to such a motor 1a, when the rotor 2a rotates and the inward projection 8 of the magnet 3a passes above the rotation detecting coil 7, an electromotive force is generated in the rotation detecting coil 7, and the electromotive force is generated. Is detected, it is possible to detect one rotation or a fraction of a rotation of the rotor 2a. However, such a motor 1
In the case of a, since the inward projection 8 is formed on the inner peripheral side of the magnet 3a, the rotational balance of the rotor 2a may be deteriorated, and the work of adjusting the rotational balance of the rotor becomes complicated. Further, on the stator substrate 5, driving stator coils are closely arranged circumferentially so as to correspond to the magnets 3a alternately arranged in the circumferential direction of N and S poles. It is necessary to install the rotation detecting coil 7 on the inner peripheral side of the coil. Therefore, the wiring taken out from the coil 7 must be designed so as to escape the layout of the stator coil. It adversely affects the driving force.

In order to improve the rotational balance of the rotor,
A method of attaching a ring-shaped magnetic material to the outer periphery of the rotor, magnetizing only a part of the material, and detecting each time the part makes one revolution is also conceivable, but in this case, the material cost is wasted, Contrary to the demand for miniaturization of motors. The present invention
In view of such circumstances, a motor that has a good rotation balance and can easily detect one or a fraction of a rotation of the rotor, but is easy to manufacture and meets the demand for miniaturization. The purpose is to provide.

[0006] The motor according to the present invention has the NS poles alternately arranged in the circumferential direction.
Ring-shaped or cylindrical magnet magnetized on
And cover one surface and outer surface of this magnet
And a case for accommodating the rotor.
At least one outer circumferential surface of the magnet
Protrusions are formed to cover the outer peripheral surface of this magnet
The protruding portion is inserted into a part of the outer cylindrical portion of the case.
Having a cut-out portion to be inserted, and the other surface of the magnet
On the surface side, a plurality of driving
The stator substrate provided with the stator coil is arranged.
On the stator substrate located on the outer periphery of the data coil,
Magnetize the passage by rotation of the protrusion formed on the magnet
A sensor for detecting the current is arranged, and the case is configured.
The specific gravity of the material forming and the material forming the magnet is
It is characterized by being substantially equal. Also, the motor of the present invention
A ring plate that is magnetized alternately with NS poles in the circumferential direction or
A cylindrical magnet, one surface of this magnet and
A case that covers the outer peripheral surface and houses the magnet
It was in the motor having a rotor, outside the magnet
At least one protrusion is formed on the peripheral surface, and the
Part of the outer peripheral cylindrical portion of the case that covers the outer peripheral surface of the socket
To have a cutout portion into which the protruding portion is inserted, said Ma
On the other surface side of the gnet, drive
Stator substrate provided with a plurality of moving stator coils
Are arranged, and a stator positioned on the outer periphery of the stator coil is provided.
The rotation of the protrusion formed on the magnet on the rotor substrate
A sensor that magnetically detects the passage
Between the surface of the magnet on the stator side and the case.
The center of gravity of the rotor is reduced
It is characterized in that a step is provided to make it smaller.

[0007]

In such a motor, the case has a cutout in a part of the case, and the protrusion formed on the outer periphery of the magnet is inserted into this part, so that the rotation balance of the rotor is improved and the rotation is improved. Work for balance adjustment is remarkably easy. In addition, since the projecting portion of the magnet is arranged on the outer periphery, a rotation detecting coil or the like as a sensor for detecting the passage of the projecting portion can be arranged on the outer peripheral side of the stator substrate. However, this does not adversely affect the layout of the driving stator coil.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a motor according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a main part of a motor according to an embodiment of the present invention, and FIG.
3 is a plan view of the stator substrate shown in FIGS. 1 and 2, FIG. 4 is a side view of the stator substrate, and FIG. 5 is a cross-sectional view of a main part showing a relationship between a magnet and a sensor. is there.
A motor 10 shown in FIG. 1 is a small motor used as a drive unit in a precision machine such as a video tape recorder (VTR). A rotating shaft 12 is provided with a case 14 and a rotating yoke 16 which also function as a yoke. Installed at intervals. A ring plate-shaped magnet 18 is mounted below the case 14 in the figure.
The case 14 covers one surface and the outer peripheral surface of the base 8. Therefore, the rotating shaft 12, the case 1
4, the magnet 18 and the rotating yoke 16 constitute the rotor 20. The case 14 and the rotating yoke 16 may be connected by means other than the rotating shaft 12. In that case, the case 14, the magnet 18, and the rotating yoke 16
Thus, the rotor 20 is configured.

[0009] Facing the other surface of the magnet 18,
The stator substrate 22 is arranged between the magnet 18 and the rotating yoke 16 so as not to contact the rotor 20. A plurality of stator coils (not shown) for driving in the circumferential direction are provided on the magnet-side facing surface of the stator substrate 22 so as to correspond to the magnetized surfaces of the magnet 18 which are alternately magnetized in the NS direction in the circumferential direction. It is arranged. By supplying a drive current to a plurality of stator coils arranged in the circumferential direction as described above, a rotating magnetic field is generated, and a rotating force acts on the magnet 18 to rotate the rotor 20. In such a motor, in the present embodiment, as shown in FIG. 2, a notch 23 is provided in a part of the outer cylindrical portion 14a of the case 14 that covers the outer periphery of the magnet 18. The magnet 18 has a projection 24 formed at an outer peripheral position thereof, and the projection 24 is inserted into the cutout 23. The tip of the projection 24 is
Preferably substantially coincides with the outer peripheral surface of the outer peripheral cylindrical portion 14a. Note that the number of the protruding portions 24 and the cutout portions 23 is not necessarily limited to one.

It is preferable that the case 14 has substantially the same specific gravity as the magnet 18 in order to improve the rotational balance of the rotor. For example, when the magnet is made of a neodymium-based magnetic material (specific gravity 7.4), the case is preferably made of a steel material (specific gravity 7.86) such as S45C. When these specific gravities are significantly different, the rotational balance can also be adjusted by adjusting the amount of protrusion of the protrusion 24 in the magnet 18. Further, in order to improve the rotational balance of the rotor, as shown in FIG.
It is preferable that a step h be provided between the end of the outer cylindrical portion 14a and the design center of each component so that the eccentricity becomes small at the design center of each component. This step h is preferably changed according to the specific gravity of the magnet 18 and the case 14, and the like.
When the magnet is made of a neodymium-based magnetic material (specific gravity 7.4) and the case is made of a steel material such as S45C (specific gravity 7.86), the step h is preferably about 0.2 mm. With such a level difference, there is no problem of leakage (leakage flux) of magnetic flux from the magnet 18 to the side. The leakage flux from the notch 23 eliminates the problem by shifting the position of the head when this motor is used in a VTR or the like. Magnet 18
Is integrally formed of, for example, a magnetic material and then magnetized. At this time, as shown in FIG.
It is preferable to magnetize the eight projections 24 so as to divide them into two. This is because the change in magnetic flux by the rotation detection coil 26 described later is detected satisfactorily.

As shown in FIGS. 3 and 4, the stator substrate 16 has a three-layer structure in which a stator coil (not shown) is arranged. A plurality of stator coils are printed in a circumferential pattern on the lowermost substrate 30 and the intermediate layer substrate 32, and the respective coils arranged on the upper and lower substrates are connected through through holes. The generated magnetic force is increased. Also, the uppermost substrate 34
Is printed with a wiring pattern (FG pattern) 36 for detecting the rotation speed of the rotor 20, and on the outer side thereof, that is, on the outer side of the stator coil, one rotation or a fraction of the rotation of the rotor 20. A wiring pattern (PG pattern) of the rotation detecting coil 26 as a sensor for detecting rotation is printed and wired. Above the rotation detection coil 26, as shown in FIG. 5, the protrusion 24 of the magnet 18 passes when the rotor rotates. When the protrusion 24 of the magnet passes above the rotation detecting coil 26, a change in magnetic flux due to the rotational movement is detected by the rotation detecting coil 26 as a pulse-like induced electromotive force. Therefore, the rotation detection coil 2
6 has a pulse generation function. In the present invention, a sensor for detecting a magnetic field when the protrusion 24 passes, such as a Hall element, may be used in addition to the rotation detecting magnetic coil. However, from the viewpoint of miniaturization of the motor,
Those that can be printed on a substrate, such as the rotation detection coil 26, are preferable.

When the rotation detecting coil 26 is used, FIG.
As shown in (A), it is preferable that the innermost peripheral pattern 26a on the rotor center side of the rotation detection coil 26 be aligned with the position of the inner diameter D of the outer cylindrical portion 14a of the case, or be located on the outer peripheral side. This is to prevent the rotation detecting coil 26 from affecting the rotating magnetic field as much as possible. From this viewpoint, it is conceivable that the outer diameter of the magnet 18 is made slightly smaller than the inner diameter of the outer cylindrical portion 14a of the case as shown in FIG. About 0.5 ~
By setting the distance to about 1 mm, it is possible to reduce the noise by about half. In order to increase the detection accuracy of the rotation detection coil 26, a magnetic material such as permalloy may be inserted in the rotation detection coil.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the magnet 18 is not necessarily a ring plate but may be a cylinder. In that case, the stator coil can be arranged on the inner periphery of the magnet. A sensor for detecting a change in magnetic flux due to the rotational movement of the protruding portion can be located at a side position of the rotor, for example, similarly to the Hall element 6 shown in FIG. 6 showing a conventional example.

[0014]

As described above, according to the motor according to the present invention, the case has the cutout portion, and the protrusion formed on the outer periphery of the magnet is inserted into this portion. Thus, the rotational balance of the rotor is improved, and the operation for adjusting the rotational balance is remarkably facilitated. In addition, since the projecting portion of the magnet is arranged on the outer periphery, a rotation detecting coil or the like as a sensor for detecting the passage of the projecting portion can be arranged on the outer peripheral side of the stator substrate. However, this does not adversely affect the layout of the driving stator coil. Therefore, the rotation efficiency of the rotor does not decrease. In addition, it is possible to easily detect one rotation or a fraction of a rotation of the rotor with a sensor such as a rotation detection coil. Furthermore, it contributes to downsizing of the motor and is easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a motor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II shown in FIG.

FIG. 3 is a plan view of the stator substrate shown in FIGS.

FIG. 4 is a side view of a stator substrate.

FIG. 5 is a sectional view of a main part showing a relationship between a magnet and a sensor.

FIG. 6 is a sectional view of a main part of a motor according to a conventional example.

FIG. 7 is a cross-sectional view of a main part on a plane side of a motor according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Motor 12 Rotating shaft 14 Case 14a Outer peripheral cylinder part 18 Magnet 20 Rotor 22 Stator board 23 Notch part 24 Projection part 26 Rotation detection coil

Claims (2)

(57) [Claims] 1. A rotor having a ring-shaped or cylindrical magnet magnetized alternately with NS poles in the circumferential direction, and a case that covers one surface and the outer peripheral surface of the magnet and houses the magnet. In the motor, at least one protruding portion is formed on the outer peripheral surface of the magnet, and a cutout portion into which the protruding portion is inserted is provided in a part of the outer peripheral cylindrical portion of the case that covers the outer peripheral surface of the magnet. On the other surface side of the magnet, a stator substrate provided with a plurality of driving stator coils opposed to the magnet is arranged, and formed on the stator substrate located on the outer periphery of the stator coil. by being arranged magnetically detecting sensors passage by the rotation of the protruding portions, make up the material and the magnet constituting the casing
A motor having a specific gravity substantially equal to that of a material . 2. A rotor having a ring-shaped or cylindrical magnet magnetized alternately with NS poles in the circumferential direction, and a case that covers one surface and the outer peripheral surface of the magnet and houses the magnet. In the motor, at least one protruding portion is formed on the outer peripheral surface of the magnet, and a cutout portion into which the protruding portion is inserted is provided in a part of the outer peripheral cylindrical portion of the case that covers the outer peripheral surface of the magnet. On the other surface side of the magnet, a stator substrate provided with a plurality of driving stator coils opposed to the magnet is arranged, and formed on the stator substrate located on the outer periphery of the stator coil. has been provided a passage by the rotation of the projecting portion is disposed is magnetically detecting sensors, put on the case with the stator-side surface of said magnet
Reduce the eccentricity of the rotor between the tip of the outer cylindrical part
A motor characterized by having a step that makes a difference .