JP2963371B2 - Brushless 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 brushless motor using a magnet in which a driving magnet for driving a rotor of a motor and a magnet for frequency generation for detecting rotation of the motor are integrally formed.

[0002]

2. Description of the Related Art A conventional general brushless motor has a frequency power generating magnet for detecting rotation of the motor and a magneto-electric conversion element for detecting a magnetic flux from the frequency power generating magnet. It is configured to detect a signal having a frequency proportional to the rotation speed of the motor and control the speed of the motor.

FIG. 10 shows an example of such a conventional brushless motor, in which only the right half with respect to the rotation center XX is shown. In FIG. 10, a cylindrical bearing holder 2 is attached to the center of the substrate 1. The bearing holder 2 protrudes downward from the center hole of the substrate 1 and has a flange portion on its outer peripheral portion. A stator core 5 is attached to a flange portion of the bearing holder 2 by screws or the like. The stator core 5 has a plurality of salient poles projecting radially from the center toward the outer periphery, and a drive coil 6 is wound around each salient pole. The drive coil 6 is connected to a predetermined drive circuit on the substrate 1 and is controlled to be energized.

A bearing 3 is mounted on the inner peripheral surface of the central cylindrical portion of the bearing holder 2 at the upper end and the lower end, respectively, and the rotating shaft 4 is rotatably supported by the bearing 3. A substantially cup-shaped rotor case 7 is attached to the upper end of the rotating shaft 4 integrally with the rotating shaft 4. An annular drive magnet 8 is attached to the inner peripheral surface of the peripheral wall of the rotor case 7, and the inner peripheral surface faces the outer peripheral surface of the stator core 5 at an appropriate interval. On the other hand, on the outer peripheral surface of the peripheral wall of the rotor case 7, a frequency power generation magnet 9 separate from the drive magnet 8 is attached. The outer peripheral surface of the frequency power generation magnet 9 faces the magnetoelectric conversion element 10 provided on the substrate 1 at an appropriate interval.

Then, based on a frequency signal from the magnetoelectric transducer 10 having a frequency proportional to the rotation speed of the motor, for example, the speed of the motor is controlled in a known manner, and the energization of the drive coil 6 is controlled. As a result, the drive magnet 8 is biased to rotate the rotor case 7 and the rotating shaft 4 integrally.

[0006]

According to the conventional brushless motor shown in FIG. 10, since the driving magnet 8 and the frequency generating magnet 9 are formed separately, both the driving magnet 8 and the frequency generating magnet 9 are used. A magnet suitable for the required characteristics can be obtained.
And the drive magnet 8
Since the manufacturing method and the manufacturing process are different from the frequency power generation magnet 9 and the frequency power generation magnet 9, they must be manufactured separately, and there is a problem that the cost increases.

As a means for solving such a problem, there is a brushless motor as shown in FIG. Such a brushless motor uses a drive magnet and a frequency power generation magnet integrally molded with an isotropic or anisotropic plastic magnet, and has an inner peripheral surface side and an outer peripheral surface side thereof with a peripheral wall of the rotor case 7 interposed therebetween. The magnet 11a on the inner peripheral surface side of the integrally formed magnet 11 constitutes a driving magnet, and the magnet 11b on the outer peripheral surface side
Constitute a magnet for frequency power generation, and the other configuration is the same as that of the example shown in FIG.

According to the example shown in FIG. 11, the drive magnet 10a and the frequency power generation magnet 10b can be manufactured in one series of manufacturing steps.
Since a plastic magnet is used, resin molding is required in the manufacturing process, and the equipment becomes large. Therefore, there is a problem that the cost cannot be reduced so much as compared with the example of FIG.

Further, in the case shown in FIG. 11, the drive magnet and the frequency power generation magnet are manufactured by using the same magnet material, and therefore, the characteristics for the drive and the frequency power generation are respectively adapted. A magnet material cannot be used, and a magnet material that emphasizes one of the characteristics, or a magnet material having an intermediate characteristic between the two, is used, so that the performance of the brushless motor cannot be improved. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to use magnets corresponding to the respective characteristics for driving and frequency power generation so that output characteristics can be improved. And FG (frequency generator)
It is an object of the present invention to provide a brushless motor that has improved characteristics and higher performance, and that is also very easy to manufacture.

[0011]

According to the first aspect of the present invention,
A brushless motor including a magnet mounted on a rotor case and integrally rotating, a stator and a magnetoelectric conversion element disposed opposite to the magnet, wherein the magnet is a flexible bond magnet and has a second anisotropy. 1
Are integrally formed by laminating a second magnet having isotropic properties with a second magnet having isotropic properties .
The magnet has a drive to obtain the rotational driving force of the motor.
Magnetized, and the second magnet is
The thickness of the second magnet is smaller than that of the second magnet, and the second magnet is magnetized for frequency power generation.
And the second magnet is opposed to the stator and the magnetoelectric conversion element, and the first magnet is
It is characterized by being opposed to the stator via a second magnet .

According to a second aspect of the present invention, the magnet is formed in an annular shape, the inner peripheral surface is magnetized for driving, and the outer peripheral surface or the end surface is magnetized for frequency power generation. It is characterized by.

The invention according to claim 3 is characterized in that an epoxy resin is mixed in the magnet. Since the epoxy resin is mixed in the magnet, by subjecting the magnet to heat treatment, the magnet is hardened and deformation due to temperature can be reduced, and the magnet can be used as a fixing means.

According to a fourth aspect of the present invention, the first magnet is fixed from the inner peripheral surface to the outer peripheral surface of the peripheral wall of the rotor case, and the second magnet is laminated so as to cover the outer surface of the first magnet. It is characterized by having.

According to a fifth aspect of the present invention, there is provided a driving magnet and a frequency power generating magnet mounted on a rotor case that rotates integrally with a rotating shaft, a stator core disposed opposite to the driving magnet and wound with a driving coil, A brushless motor comprising: a magnetoelectric conversion element disposed to face a frequency power generation magnet, wherein the drive magnet is formed of a first flexible bond magnet having anisotropy, and the frequency power generation magnet is provided. The second flexible bond magnet is constituted by a second flexible bond magnet having an isotropic property such that the second flexible bond magnet is located on the surface side of the first flexible bond magnet. And the first flexible bond magnet are laminated and attached to a rotor case, and the second flexible bond magnet is subjected to magnetoelectric conversion. Together to face the child, the first flexible bond magnet and the stator core, characterized in that faces in a state of being interposed between the second flexible bond magnet.

According to a sixth aspect of the present invention, the first or second flexible bond magnet is obtained by adding rubber or a binder having rubber-like elasticity to magnetic powder so as to have a magnetic powder filling rate of 85 to 95%. It is characterized by the following.

According to a seventh aspect of the present invention, the thickness of the second flexible bond magnet is smaller than the thickness of the first flexible bond magnet.

The invention according to claim 8 is characterized in that the thickness of the second flexible bond magnet is set in the range of 0.1 mm to 0.5 mm.

According to a ninth aspect of the present invention, the first and second flexible bond magnets have a magnetic powder filling ratio of 85 to 95% by adding rubber or a binder having rubber-like elasticity to the magnetic powder. An epoxy resin is kneaded in at least one of the first and second flexible bond magnets.

Since the second magnet is an isotropic magnet having fine particles, it can be easily magnetized at a fine magnetized pitch. By using this as an FG magnet, FG characteristics can be improved. Since the first magnet is an anisotropic magnet, it can be easily magnetized by strong magnetic force, and a large driving force can be obtained by using this as a driving magnet. Even when the second magnet faces the stator, the second magnet does not hinder the magnetic flux from the first magnet because the second magnet is thinner than the first magnet.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a brushless motor according to the present invention will be described with reference to the drawings. In addition,
The same components as those of the conventional example shown in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted.

1 to 3, an annular magnet 18 is attached to the peripheral wall of the substantially cup-shaped rotor case 7. As shown in FIG. The magnet 18 is made of a flexible bond magnet, and is formed by laminating the first magnet 16 and the second magnet 17.

A flexible bond magnet is prepared by mixing a magnetic substance with an organic binder having rubber-like elasticity, or adding a magnetic substance powder to a binder obtained by adding an additive to rubber or a synthetic resin having rubber-like elasticity. And is known from Japanese Patent Application Laid-Open No. Sho 60-164314, so that the detailed description is omitted here.

The first magnet 16 is fixedly formed from the inner peripheral surface to the outer peripheral surface of the peripheral wall of the rotor case 7. An outer peripheral surface of the first magnet 16 has a protruding portion 16 a protruding in a flange shape from the center side of the rotor case 7 toward the outer periphery.
Are formed. The first magnet 16 is an anisotropic magnet that can be easily magnetized by a strong magnetic force and can obtain a large driving force. The direction of the strong magnetic force is perpendicular to the inner circumferential surface of the rotor case 7 as usual. Formed in different directions. In the present embodiment, rubber or a binder having rubber-like elasticity is added to an anisotropic magnet material, for example, FS-317 magnetic powder manufactured by Toda Kogyo which is anisotropic strontium ferrite, and the magnetic powder filling rate is 85% to 95%. What was rolled by% was used.

The second magnet 17 is laminated so as to cover the outer surface of the first magnet 16 and passes from the inner peripheral surface to the lower end surface (the upper end surface in FIG. 2) of the first magnet 16. The protrusion 16a is formed over the outer peripheral surface. The second magnet 17 is formed thinner than the first magnet 16 and has a plate thickness of 0.1.
It is set in the range of 0.5 mm to 0.5 mm.

The second magnet 17 is made of an isotropic magnet which is easy to magnetize at a fine magnetizing pitch because the magnetic powder particles are fine. In the present embodiment, after rolling the first magnet, an isotropic magnet material, for example, GP-500 manufactured by Toda Kogyo which is an isotropic barium ferrite.
Rubber or a binder having rubber-like elasticity was added to the magnetic powder, and the magnetic powder was rolled on one surface of the first magnet at a magnetic powder filling rate of 85% to 95% and heat-treated. The inner peripheral surface 17a of the second magnet 17 faces the outer peripheral surface of the stator core 5 at an appropriate interval, and the outer peripheral surface 1a protruding in the outer peripheral direction.
Reference numeral 7b faces the magnetoelectric conversion element 10 provided on the substrate 1 at an appropriate interval.

The inner peripheral surface 18 of the magnet 18
From the side a, magnetization for driving necessary for rotationally driving the motor is performed, and from the outer peripheral surface 18b side, magnetization for frequency generation necessary for detecting rotation of the motor is performed. Is done.

Next, the thickness of the second magnet is set to 0.
The reason for setting the range of 1 mm to 0.5 mm will be described. In FIG. 4, the TF curve is a graph showing the relationship between the thickness of the second magnet for frequency power generation and the FG wow / flutter characteristics.
Is measured by changing the thickness of the second magnet while rotating the FG. The TT curve is a graph showing the relationship between the thickness of the second magnet and the starting torque of the motor.

In the present invention, the first magnet 16 for driving the motor and the second magnet 17 for generating the frequency are provided.
Are used in a laminated state. Therefore, the influence of one magnet on the other magnet must be considered. Considering this point with reference to FIG. 4, as shown in FIG. 4, as the thickness of the second magnet 17 for frequency generation increases, the anisotropic magnet (the first magnet for driving the motor) increases. 16), the FG wow and flutter occurrence rate decreases, and the FG wow and flutter characteristics improve. However, the plate thickness of the second magnet 17 is constant (about 0.3 m in FIG. 4).
When the value exceeds m), the FG wow and flutter characteristics cannot be further improved.

On the other hand, the second magnet 1 for frequency power generation
When the plate thickness of the first magnet 16 is increased, the second magnet 17 is laminated so as to cover the outer surface of the first magnet 16. The magnetic flux of 16) is interrupted, and T- in FIG.
As shown by the T curve, the driving torque of the motor gradually decreases.

Therefore, if the thickness of the second magnet 17 is set within the range of 0.1 mm to 0.5 mm, which is a favorable range for both, the FG accuracy is maintained good and the starting torque of the motor is reduced. It can have little effect.

As described above, the second magnet 1
When the driving magnetizing is performed on the first magnet 16 through the magnet 7, the magnet is magnetized by a strong magnetic field due to a strong magnetic force, so that the magnet penetrates the second magnet 17 and magnetizes the first magnet 16. When the thickness of the second magnet 17 is set within the above range, the driving force of the first magnet 16 is hardly affected.

On the other hand, even if the second magnet 17 is magnetized for FG, the magnetization for FG is not due to the strong magnetic force but is a minute magnetization, so that it hardly penetrates to the first magnet 16. There is almost no influence of the magnetic flux of the first magnet 16, and a stable magnetized output without unevenness can be obtained.

Next, a method for manufacturing the magnet will be described with reference to FIGS.

First, as shown in FIG. 6, an anisotropic magnetic powder constituting the first magnet 16 and a binder are kneaded by a kneading machine 30, and this is rolled by rollers 32, 32 to form a sheet. I do. The isotropic magnetic powder constituting the second magnet and the binder are kneaded by a kneader 31 and are rolled to one side of the sheet-like first magnet by rollers 32 and 32. Thereafter, a heat treatment is performed on the sheet magnet by a predetermined heat treatment means (not shown) to obtain a roll sheet magnet 18A.

In the above process, the first magnet 16
Alternatively, either one of the second magnets 17 or both the first magnet 16 and the second magnet 17 may be kneaded with an epoxy resin, whereby the resin is fixed to the rotor case 7 and then heated and cured. Thereby, the deformation due to the temperature change can be reduced, and it can also be used as a fixing means. Further, the step of forming the first magnet 16 and the step of forming the second magnet 17 may be a series of steps, or may be separate steps.

As shown in FIG. 7, a strip-shaped magnet 18 is obtained by cutting the roll-sheet-shaped magnet 18A into appropriate dimensions. Then, as shown in FIG. 8, the magnet 18 is assembled in the rotor case 7 with the second magnet 17 facing inside.

When the magnet 18 is simply incorporated into the rotor case 7, the end 18b protrudes from the lower end surface of the rotor case 7 as shown by a dotted line in FIG. Then, the end 18b of the magnet 18 protruding from the rotor case 7 is compression-molded and bent until it comes into contact with the outer peripheral wall of the rotor case 7 using a jig (not shown). Thus, the magnet 18 is fixed to the rotor case 7 so as to cling to the peripheral wall of the rotor case 7, and the second magnet 17 surrounds the first magnet 16. Then, the magnet 18
Is formed on the inner peripheral surface side of the substrate and magnetized for frequency power generation on the outer peripheral side or the lower end (the upper end in FIG. 4), thereby completing the formation of the magnet.

As described above, according to the embodiment shown in FIGS. 1 to 3, the magnet 18 is a flexible bond magnet and is isotropic with the first magnet 16 having anisotropy. The second magnet 17 is formed by laminating the second magnet 17 and the second magnet 17 is formed to be thinner than the first magnet 16. Since it is opposed to the conversion element 10, the anisotropic first magnet 16 is easy to be magnetized for driving by strong magnetic force, and the isotropic second magnet 17 is fine. Magnetization for power generation at a high pitch can be easily performed, and a magnet suitable for each characteristic can be used.

Even if the second magnet 17 faces the stator core 5, the second magnet 17 is thinner than the first magnet 16, so that the first magnet 1
The large driving force can be obtained without obstructing the magnetic flux from 6. Further, even if the second magnet 17 is magnetized for frequency power generation, the magnetization is not caused by a strong magnetic force but is minute, so that the first magnet 16 is not affected, and an accurate FG output is obtained. Obtainable.

Next, another embodiment of the present invention will be described with reference to FIG. 1 to 3 described above.
The same components as those of the embodiment shown in FIG.

In FIG. 5A, an annular magnet 20 made of a flexible bond magnet provided on the peripheral wall of the rotor case 7 includes a first magnet 21 and a second magnet 22. The magnet 20 does not project from the outer peripheral surface of the peripheral wall of the rotor case 7. The second magnet 22 is a first magnet 2
The plate thickness is thinner than 1. And magnet 2
The magnetizing for driving is performed from the side of the inner peripheral surface 20a of No. 0, and faces the stator outer peripheral surface (not shown) at an appropriate interval. The lower end surface 20b of the magnet 20 is magnetized for frequency power generation.
“b” faces a magnetoelectric conversion element (not shown) at an appropriate interval. For other configurations, see FIGS.
This is the same as the embodiment shown in FIG.

In FIG. 5B, the magnet 25 made of a flexible bond magnet attached to the peripheral wall of the rotor case 7 is composed of a first magnet 26 and a second magnet 27. 2 magnets 2
7 is thinner than the first magnet 26. The inner peripheral surface 25a of the magnet 25 is magnetized for driving, and is opposed to a not-shown stator at an appropriate interval. A flange-like protrusion 25b is formed from the lower end of the magnet 25 toward the outer periphery, and the flat outer periphery of the protrusion 25b is magnetized for frequency power generation. The outer peripheral surface of the protruding portion 25b faces a magneto-electric conversion element (not shown) at an appropriate interval. Other configurations are the same as those of the embodiment shown in FIGS.

5 (a) and FIG. 5 (b), the same effects as those of the embodiment shown in FIGS. 1 to 3 can be obtained.

[0045]

According to the present invention, the magnet is a flexible bond magnet, which has a first magnet having anisotropy that is easily magnetized by a strong magnetic force and a magnet having a fine magnetized pitch. It is formed by laminating a second magnet having easy isotropy, and the second magnet is formed to be thinner than the first magnet. While the driving magnetization can be performed on the anisotropic first magnet,
Magnetization for fine pitch frequency power generation can be performed on the second magnet having isotropic properties, and magnets corresponding to the respective characteristics of driving and frequency power generation can be used, and output characteristics can be obtained. And a FG (frequency generator) characteristic and a brushless motor which is very easy to manufacture.

Even if the second magnet is opposed to the stator core, the second magnet is set to a certain predetermined value which is thinner than the first magnet, so that the influence on the magnetic flux from the first magnet can be reduced. Since the thickness can be set to be small, a sufficient driving force can be obtained as the driving force of the motor.

Further, since the magnet is formed by mixing epoxy resin, the magnet can be cured by applying a heat treatment to reduce deformation due to temperature, and can also be used as fixing means.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a magnet and a rotor case according to the embodiment;

FIG. 3 is a sectional view of the magnet in the embodiment.

FIG. 4 is a graph showing the relationship between the thickness of the second magnet and FG wow and flutter, and the relationship between the thickness of the second magnet and the starting torque in the embodiment.

FIG. 5 is a sectional view showing a main part of another embodiment according to the present invention.

FIG. 6 is a schematic view showing one step in a manufacturing process of the magnet in the embodiment.

FIG. 7 is a perspective view showing another step in the manufacturing process.

FIG. 8 is a perspective view showing still another step in the manufacturing process.

FIG. 9 is a sectional view showing still another step in the manufacturing process.

FIG. 10 is a sectional view showing an example of a conventional brushless motor.

FIG. 11 is a sectional view showing another example of a conventional brushless motor.

[Explanation of symbols]

 Reference Signs List 5 stator core 7 rotor case 10 magnetoelectric conversion element 16 first magnet 17 second magnet 18 magnet 20 magnet 21 first magnet 22 second magnet 25 magnet 26 first magnet 27 second magnet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 29/14 H02K 1/27 502 H02K 15/03 H02K 21/22 H02K 29/00

Claims (9)

(57) [Claims] 1. A brushless motor comprising a magnet mounted on a rotor case and rotating integrally therewith, and a stator and a magnetoelectric conversion element disposed opposite to the magnet, wherein the magnet is a flexible bond magnet. So,
The first magnet having anisotropy and the second magnet having isotropic properties are integrally formed by laminating, and the first magnet obtains a rotational driving force of a motor.
Driving magnetization has been applied for, the second magnet, together with the plate thickness than the first magnet is formed thinly, this second magnet
Are magnetized for frequency generation, the second magnet faces the stator and the magnetoelectric conversion element, and the first magnet is
A brushless motor facing the stator via a second magnet . 2. The brushless motor according to claim 1, wherein the magnet is formed in an annular shape, the inner peripheral surface is magnetized for driving, and the outer peripheral surface or the end surface is magnetized for frequency power generation. . 3. The brushless motor according to claim 1, wherein the magnet is mixed with an epoxy resin. 4. A first magnet is fixed from an inner peripheral surface to an outer peripheral surface of a peripheral wall of a rotor case, and a second magnet is laminated so as to cover an outer surface of the first magnet. Brushless motor. 5. A drive magnet and a frequency power generation magnet attached to a rotor case that rotates integrally with a rotating shaft, a stator core disposed opposite to the drive magnet and wound with a drive coil, and the frequency power generation. A brushless motor comprising: a magnetoelectric conversion element disposed opposite to a driving magnet, wherein the driving magnet is constituted by a first flexible bond magnet having anisotropy, and the frequency generating magnet is A second flexible bond magnet having an isotropic property, wherein the second flexible bond magnet is positioned on the surface side of the first flexible bond magnet; A flexible bond magnet and the first flexible bond magnet are laminated and attached to the rotor case; And a first flexible bond magnet and the stator core are opposed to each other with the second flexible bond magnet interposed therebetween. And a brushless motor. 6. The first or second flexible bond magnet is characterized in that rubber or a binder having rubber-like elasticity is added to magnetic powder to make the magnetic powder filling rate 85 to 95%. A brushless motor according to claim 5. 7. The brushless motor according to claim 6, wherein the thickness of the second flexible bond magnet is smaller than the thickness of the first flexible bond magnet. 8. The brushless motor according to claim 7, wherein the thickness of the second flexible bond magnet is set in a range from 0.1 mm to 0.5 mm. 9. The first and second flexible bond magnets further comprise rubber or a binder having rubber-like elasticity added to the magnetic powder to achieve a magnetic powder filling rate of 85 to 95%. The brushless motor according to claim 5, wherein an epoxy resin is kneaded into at least one of the second flexible bond magnets.