JP7108378B2 - motor and magnet - Google Patents

Description

The present invention relates to motors and magnets.

In Patent Document 1, a magnet, a yoke arranged on the outer circumference of the magnet, an iron core arranged on the inner circumference of the magnet, and a rotating shaft holding the iron core are provided. A motor is disclosed that is formed with a pair of grooves extending to the .

Japanese Patent No. 5481160

However, in the motor of Patent Literature 1, the magnet has a thick portion serving as the center of the magnetic pole and a thin portion serving as a boundary between the magnetic poles along the circumferential direction.

In addition, since the radial magnetization of the magnet is complicated and the shape of the groove is inclined, it is difficult to mold with a mold, and the groove must be formed by secondary processing. Moreover, since the mold becomes large and complicated, the investment cost becomes bloated.

In addition, when the magnet is lengthened, the inner diameter of the magnet becomes tapered due to the tapered shape of the mold, and the gap between the core and the magnet gradually widens, thereby degrading the motor characteristics. Therefore, it is difficult to increase the output by increasing the length.

In addition, if the magnet is divided into the number of poles in order to lengthen the magnet, the cogging torque increases, resulting in poor controllability.

In view of such problems, the present invention provides a motor that is easy to handle, can be manufactured easily and inexpensively, can be increased in output, and can reduce cogging torque, and a magnet attached to the motor. intended to

A motor as one aspect of the present invention includes an outer cylinder made of a magnetic material, a plurality of magnets arranged on the inner surface of the outer cylinder, and a core rotatably arranged inside the plurality of magnets. , and each of the plurality of magnets is magnetized in parallel, and each of the plurality of magnets has a plurality of magnetic circuits between the plurality of magnets and the core and inside the outer cylinder in the circumferential direction of each of the plurality of magnets. A plurality of grooves are formed so as to occur on one side, and in each of the plurality of magnets, the plurality of grooves are formed in the contact surface with the outer cylinder in the axial direction, and each side surface of the plurality of grooves , is formed perpendicular to the contact surface.

Also, a magnet as another aspect of the present invention is attached to a motor having an outer cylinder made of a magnetic material and a rotatably arranged core on the inner surface of the outer cylinder and the outer side of the core. The magnet is magnetized in parallel, and when the magnet is attached to the motor, a plurality of magnetic circuits are generated on one side of the magnet in the circumferential direction between the magnet and the core and inside the outer cylinder. In the magnet, the plurality of grooves are formed in the contact surface with the outer cylinder in the axial direction, and the side surfaces of each of the plurality of grooves face the contact surface. characterized in that it is formed vertically

Advantageous Effects of Invention According to the present invention, it is possible to provide a motor that is easy to handle, can be manufactured easily and inexpensively, can have a high output, and can reduce cogging torque, and a magnet attached to the motor.

1 is a longitudinal sectional view of a motor according to an embodiment of the invention; FIG. Fig. 2 is a perspective view of a magnet attached to a motor; FIG. 4 is an FEM result diagram showing the flow of magnetic flux in the motor when the magnets are not grooved; FIG. 10 is an FEM result diagram showing the flow of magnetic flux in the motor when the magnets are grooved; FIG. 4 is a diagram showing the positional relationship between the core and grooves formed in the magnet; FIG. 4 is a diagram showing the change rate of the magnetic flux density of the magnetic center of the magnet; It is a figure which shows the rate of change of the magnetic flux density of an outer cylinder. 4 is a comparison diagram of cogging torque; FIG. FIG. 4 is a diagram showing ratios of cogging torque, interlinkage magnetic flux, and induced voltage;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to the same members, and overlapping descriptions are omitted.

First, the configuration of a motor 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of a motor 1 according to an embodiment of the invention.

The motor 1 has a core 2, an outer cylinder 3, magnets 4a and 4b, a rotating shaft 5, and motor drive coils U1, V1, W1, U2, V2, and W2.

The core 2 is formed of a magnetic material (for example, a laminate of electromagnetic silicon steel sheets, a sintered iron-silicon combination, or a cut piece of steel), and is rotatably held on the rotating shaft 5. .

The outer cylinder 3 is made of a magnetic material (for example, a sintered combination of iron and silicon, a cut piece of steel, or a sheet metal of steel).

The magnets 4a and 4b are bonded magnets made of magnetic powder (for example, NdFeB) and binder resin (for example, polyphenylene sulfide resin (PPS)). are arranged differently in the Magnets 4a and 4b are magnetized in parallel and are isotropic or anisotropic magnets. In addition, the magnets 4a and 4b are divided by the number of poles (in this embodiment, four poles, so four divisions (two magnets 4a and two magnets 4b)). That is, in this embodiment, the magnets 4a and 4b are arranged rotationally symmetrical with respect to the center of rotation of the core 2, respectively.

The rotating shaft 5 is arranged at the center of rotation of the core 2 and holds the core 2 . Further, the rotary shaft 5 is supported by bearings (not shown).

The motor drive coils U1, V1, W1, U2, V2, and W2 are formed of conductor wires such as copper wires and aluminum wires.

The configuration of the magnets 4a and 4b will be described below. FIG. 2 is a perspective view of magnets 4a and 4b.

As shown in FIG. 2, the contact surface between the magnets 4a and 4b and the inner surface of the outer cylinder 3 has a plurality of (in this embodiment, two) axially extending from the upper end surface toward the lower end surface. A groove 6 is formed. The two grooves 6 formed in each magnet generate a magnetic circuit inside the outer cylinder 3 between the core 2 disposed inside the magnets 4a and 4b with an air gap therebetween.

FIG. 3 is a result diagram of FEM (Finite Element Method) showing the flow of magnetic flux in the motor 1 when the groove 6 is not formed. FIG. 4 is an FEM result diagram showing the flow of magnetic flux in the motor 1 when the grooves 6 are formed.

As shown in FIG. 3, a magnetic circuit 7a is generated between the magnets 4a, 4b and the core 2 and inside the outer cylinder 3. As shown in FIG. In this embodiment, the side surfaces of the two grooves 6 are formed perpendicular to the contact surface between the magnets and the outer cylinder 3, so that the magnets 4a, 4b and Between the core 2 and inside the outer cylinder 3 , not only the magnetic circuit 7a but also the magnetic circuit 7b is generated.

FIG. 5 is a diagram showing the positional relationship between the core 2 and the grooves 6. As shown in FIG. A straight line 8 represents a straight line passing through the center of rotation of the core 2 and the tip of the outer diameter of the core 2 . At least one or more of the grooves (first grooves) of the grooves 6 formed in each magnet has a starting angle 9 of 1 degree to a final angle of 1 degree to the magnetic center 11 side of the magnets 4a and 4b with respect to the straight line 8. 10 is formed within 6 degrees. At least one or more paired grooves (second grooves) are formed line-symmetrically with respect to the magnetic center 11 .

FIG. 6 is a diagram showing the change rate of the magnetic flux density of the magnetic center 11. As shown in FIG. FIG. 7 is a diagram showing the change rate of the magnetic flux density of the outer cylinder 3. As shown in FIG.

As shown in FIG. 6, in this embodiment, the number of magnetic flux flow paths is increased, and the rate of change in magnetic flux density passing through the magnetic center 11 is smaller than in the case where the grooves 6 are not formed. On the other hand, as shown in FIG. 7, the change rate of the magnetic flux density passing through the outer cylinder 3 does not change with respect to the case where the groove 6 is not formed. That is, the flux flow through the magnetic center 11 is distributed. Therefore, cogging torque can be reduced.

FIG. 8 is a comparison diagram of cogging torque. FIG. 9 is a diagram showing ratios of cogging torque, interlinkage magnetic flux, and induced voltage.

As shown in FIG. 8, the number of peaks (=least common multiple of the number of poles and the number of slots) per revolution of the coking torque of the motor 1 with a boundary of 0 (zero) depends on the arrangement position and depth of the groove 6. It is multiplied by a natural number (three times is the best embodiment in this embodiment). As a result, the rotational resistance of the rotating shaft 5 due to the cogging torque is smoothed.

Also, as shown in FIG. 9, when the depth of the groove 6 is 1% to 60% of the width of the groove, the cogging torque is reduced. In this embodiment, when the groove width is 0.3 mm, the best mode is that the groove depth is 0.1 mm, which is about 33% of the groove width. At this time, the cogging torque is reduced by about 70%. Even if the cogging torque is reduced, there is no effect on the interlinkage magnetic flux and the induced voltage, so there is no effect on the torque constant.

As described above, the motor 1 of the present invention is easy to handle because it has a structure in which the magnets 4a and 4b do not have thin portions that serve as boundaries between magnetic poles. The magnets 4a and 4b are magnetized in parallel, and the side surface of the groove 6b is formed perpendicular to the contact surface between the magnets and the outer cylinder. Since no processing is required, the motor 1 can be easily manufactured. In addition, since the mold for molding the magnet is not complicated, it is possible to suppress an increase in investment cost. In addition, since the motor 1 can be manufactured so that the inner sides of the magnets 4a and 4b are not tapered but parallel to the outer side, it is possible to increase the output by lengthening the magnets 4a and 4b. Furthermore, in the motor 1, the magnetic flux passing through the magnetic center 11 is dispersed by the grooves 6 formed in the magnets 4a and 4b, and the cogging torque is reduced, so controllability can be improved.

The method for reducing cogging torque in a motor according to the present invention can be suitably used not only for small DC motors, but also for large DC motors, AC motors, linear motors, actuators, and the like.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

1 motor 2 core 3 outer cylinder 4a, 4b magnet 6 groove

Claims (6)

an outer cylinder made of a magnetic material;
a plurality of magnets arranged on the inner surface of the outer cylinder;
a core rotatably arranged inside the plurality of magnets;
each of the plurality of magnets is magnetized in parallel,
Each of the plurality of magnets has a plurality of grooves such that a plurality of magnetic circuits are generated on one side of each of the plurality of magnets in the circumferential direction between the plurality of magnets and the core and inside the outer cylinder. is formed and
In each of the plurality of magnets, the plurality of grooves are axially formed in the contact surface with the outer cylinder,
A motor according to claim 1, wherein each side surface of each of the plurality of grooves is formed perpendicular to the contact surface. 2. The motor according to claim 1, wherein the depth of each of said plurality of grooves is 1% to 60% of the groove width. 3. The motor according to claim 1, wherein when the groove width of each of the plurality of grooves is 0.3 mm, the depth of each of the plurality of grooves is 0.1 mm. A first groove among the plurality of grooves is formed within a range of 1 degree to 6 degrees on the magnetic center side of the magnet with respect to a straight line passing through the center of rotation of the core and the tip of the outer diameter of the core,
4. The motor according to any one of claims 1 to 3, wherein the second grooves different from the first grooves are formed line-symmetrically with respect to the magnetic center. The plurality of grooves are formed so that the number of peaks of the cogging torque of the motor is a natural number times the number of peaks of the cogging torque of the motor when the grooves are not formed in the magnet. 5. A motor according to any one of claims 1 to 4, characterized in that A magnet attached to a motor having an outer cylinder made of a magnetic material and a rotatable core, on the inner surface of the outer cylinder and on the outer side of the core,
the magnets are parallel magnetized,
The magnet has a plurality of grooves so that a plurality of magnetic circuits are generated on one side of the magnet in the circumferential direction between the magnet and the core and inside the outer cylinder when the magnet is attached to the motor. is formed and
In the magnet, the plurality of grooves are formed in the axial direction on the contact surface with the outer cylinder,
A magnet, wherein each side surface of each of the plurality of grooves is formed perpendicular to the contact surface.

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