JPS6158456A - Motor - Google Patents

Abstract

PURPOSE:To enable a motor of less cogging to be produced with high productivity, by a method wherein a face confronting a salient pole is notched between magnetized areas of a ring-formed magnet, and wherein a slightly magnetized intermediate area is provided. CONSTITUTION:A ring-formed magnet 2 is magnetized with poles N 21 and poles S 22 alternately at the same width in the circumferential direction, and intermediate areas 23 are arranged respectively between the magnetized areas 21 and 22. The intermediate areas 23 are arranged essentially to have the same width, and notched sections 24 are provided for sections confronting salient poles 11, and the intermediate areas 23 are arranged to be magnetized with magnetic intensity equal to or less than that in the magnetized areas 21, 22. As the result, non-magnetized areas can be easily formed on the ring-formed magnet 1, and a motor of less cogging and large torque generation can be easily produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor equipped with a ring-shaped magnet magnetized with multiple poles in the radial direction and a core having salient poles arranged inside or outside the magnet. The present invention relates to a motor characterized in that cogging that occurs during rotation is completely reduced by providing a magnetized region and an intermediate region having a notch.

BACKGROUND OF THE INVENTION In recent years, with the development of new mechanical devices, electrical and electronic devices, there has been a strong desire for small, high-quality motors with less cogging and a large amount of torque.

Coreless motors and the like have been used as a countermeasure against cogging, but coreless motors cannot obtain sufficiently large torque, and in order to obtain large torque, it is necessary to increase the size of the motor. On the other hand, although motors with salient poles can provide large torque, they have the disadvantage of causing cogging.

Conventionally, motors with salient poles (hereinafter simply referred to as motors) have been used to reduce cogging, for example, the Sho JR-J? As disclosed in the publication No. 2≠2, a method of processing the armature core has been proposed, but this method is complicated, and the reduction of cogging is difficult to achieve due to the ever-increasing demand for higher quality. It was not sufficient for the request.

Furthermore, recently, with the use of rarefied magnets with strong magnetic force as permanent magnets, although miniaturization has been promoted, cogging has become more pronounced and practical inconveniences have increased.

In order to solve the above-mentioned drawbacks, the present inventors have developed a motor using a ring-shaped magnet magnetized with multiple poles in the radial direction. Whereas the areas were divided equally and magnetized with almost no gaps, we discovered that cogging could be reduced by providing non-magnetized areas between the magnetized areas. This was proposed in the special request for the Shoj Tata L/6/Tata issue.

However, in subsequent experiments, it was discovered that when producing ring-shaped magnets on an industrial level, that is, magnetizing them while maintaining the non-magnetized region, there are many difficulties with the current technology.

As a result of further research in order to solve the above problem, the inventors of the present invention found that by providing a ring-shaped magnet with an intermediate 9-wall with a part cut out between the magnetized regions, it is possible to achieve an extremely high productivity in terms of production. The present invention has been achieved by discovering that it is easy to use 9 and reduces cogging.

Means for Solving the Problem The motor of the present invention uses a ring-shaped magnet, and the magnet has a substantially uniform composition in each cross section perpendicular to the central axis of the ring, and has a north pole. and B poles are alternately magnetized with substantially the same width, each magnetized region being separated by an intermediate region, each intermediate region having substantially the same width, and each of the magnetized regions having substantially the same width. The portion facing the salient pole is notched, and the strength of magnetization on the surface of this portion is equal to or weaker than the strength of magnetization on the surface of the portion of the magnetized region facing the salient pole. Being f: It is a characteristic.

The present invention will be explained in detail below.

Figure @1 is a schematic cross-sectional view of an inner rotor type motor which is an example of the motor of the present invention. This inner rotor type motor is composed of a core/ having two salient poles l/, a ring-shaped magnet λ whose number of magnet poles is ≠, and a magnetic yoke 3 as main parts.

This ring-shaped magnet is morphologically no different from a normal one, and has a substantially uniform composition in each ICF plane perpendicular to the central axis of the ring. Magnetized regions and intermediate regions having notches exist alternately.

In other words, N poles 2/ and S poles 22 are magnetized alternately and with substantially the same width, and a notch is provided between the N poles 2/ and S poles 22 in the portion facing the salient pole L/. There is an intermediate region 23 with two sides. Each intermediate region also has substantially the same cutout shape and width.

The rod-shaped magnet used in the present invention can be manufactured by various methods. For example, magnetic powder such as ferrite powder or cloth magnet powder is molded into a shape with a notch as shown in the ring-shaped magnet λ in FIG. 1, and then sintered to form a ring-shaped molded body. Alternatively, a ring-shaped molded body having the above shape is manufactured by kneading magnetic powder with rubber or plastic. The ring-shaped molded body thus obtained is magnetized using a magnetizer so that north poles and south poles are arranged alternately. At this time, the magnetized region is strongly magnetized by direct contact with the magnetizing yoke, but in the intermediate region 23 with the notch 2≠, the magnetizing yoke directly contacts the inside of the intermediate region 23 due to the notch 24t. Therefore, the magnetization of the intermediate region 3 is naturally weakened using a normal method. Further, from approximately the center of the intermediate region 23 to the half of the magnetized region λl near the N pole, it is magnetized to N%,
The half of the magnetized region 22 near the S pole is magnetized to the S pole.

In addition, in the plastic magnet of the present application, it is preferable that during the molding process, the magnetic powder is completely oriented in the radial direction to form a molded body having anisotropy, and then this is magnetized as described above. magnets can be manufactured. In order to orient magnetic powder in the radial direction, Japanese Patent Application Sho sr-jIA/JF Ya% Ganshoj 5'-IA
All the methods described in 22 A 9 K can be suitably used.

'l:'fc1 When oriented in the radial direction, if only the magnetized region is oriented without the intermediate or subregion metal orientation, even if the intermediate region is slightly magnetized during magnetization, the magnetic flux will be This is preferable because the density can be reduced.

Further, although the present invention has been described above regarding radial isotropic magnets, it goes without saying that the present invention can also be used for radially isotropic magnets.

It is preferable to carry out magnetization so as to obtain as uniform a magnetic flux density as possible over the entire region of each magnetized region, and usually the maximum magnetic flux density of that region ( It is magnetized so that the straightness is /, 2 or less, preferably /, / or less. It is most preferable if the magnetization can be done so that the magnetic flux density is constant over the entire width of the magnetized region.

To explain the relationship between cogging in the motor of the present invention and the intermediate region having a notch in the ring-shaped magnet, cogging refers to rotational unevenness that occurs during rotation, and is particularly noticeable at the beginning of startup and before stopping. The reason for this is that the operating point of the magnet changes depending on the relative rotational position between the salient pole // and each magnetic pole of the ring-shaped magnet 2, and the force acting on the magnetic pole is not symmetrical with respect to the rotation axis. It is brought about by the force (cogging force) that occurs when

Therefore, if there is an intermediate region having a notch in the part facing the salient pole of an appropriate width between each magnetic pole of the ring-shaped magnet 2, the force acting on each part of the magnetic pole will be in a nearly balanced state with respect to the rotation axis. As a result, cogging is reduced.

For example, Figure 2 shows the torque (cogging force) percentage versus rotation angle (ψ) when the t motor shown in Figure 1 is rotated in a non-energized state and based on the state in Figure 1. It is a diagram.

Curve a in Fig. 2 is a conventional ring-shaped magnet with a magnetization angle (θ) of O'' and no intermediate region, and curves c and d each have a magnetization angle (θ) of 7.26. This is the case using a ring-shaped magnet with the remainder being an intermediate region having seven notches at .66@ and j.
If the ring-shaped magnet is provided with an intermediate region with a notch (fc), the torque (cogging force) that causes cogging in the motor is small, and the rotation angle of the rotor (ψ
) changes in torque are also small.

Further, FIG. 3 is a diagram showing torque (cogging force) characteristics with respect to rotation angle (ψ) in a non-energized state of an inner rotor type motor having three salient poles and a magnet pole number λ.

Curves e, f, and g in Figure 3 are magnetization angles (θ), respectively.
This is the case when /206, /300 and /Hiro θ° glue/G-shaped magnets are used.

Figures ≠ and 5 are diagrams showing the relationship between the absolute value of the maximum torque, which is the cogging force, and the magnetization angle (θ) of the ring-shaped magnet for the motors shown in Figures 1 and 3, respectively. It is. As is clear from Figures ≠ and 5, the cogging force becomes extremely small when the magnetization angle t (θ) is extremely limited, that is, when the magnetization region and intermediate region are within a specific range. I understand. For each motor, the magnetization angle (θ) at which the maximum torque is the smallest is around 44' for a motor with the number of salient poles O and the number of magnet poles ≠, the number of salient poles is 3, and the number of magnet poles is ≠. For a motor consisting of 2, approximately 33°
In a motor with a salient pole number of /2 and a magnet pole number of t, there is a recess around 33°.Similarly, the absolute value of the maximum torque and the magnetization corner(
θ), there is a tendency that is almost the same as the characteristics shown in FIGS.

Therefore, the magnetization angle at which the absolute value of the maximum torque is the smallest is (
3to"/number of salient poles) It has the disadvantage that the rotational torque of the motor decreases as the area decreases.Therefore, from a practical standpoint, the N output angle is
(j60°/number of salient poles) x (t, o s~/, / j
) is preferably within the range.

Further, in the motor of the present invention, it is preferable that the ratio of the number of salient poles of the core to the number of poles of the magnet is 3:2, which is the most common ratio.
Anything other than this is also fine.

The above explanation assumes that the thickness of the magnet is /x, the distance (La) between the magnet and the salient pole is o, jrrrm, and the thickness of the notch! !
The case where r) is ρ and frran has been described, but in the present invention, the maximum torque value involved in cogging also changes depending on the ly/La value and the value of the strength of magnetization due to magnetization in the intermediate region.

Figure 6 shows the maximum cogging force and AylLG under the above conditions.
It is a figure showing the relationship with a value. Curves h, 1 and j are the relative strength of magnetization of the surface of the part facing the salient pole at the notch with respect to the magnetized part. , o, r and O,X S. From FIG. 2, it is clear that when γ is greater than /, 0, the effect of reducing the maximum torque is extremely large, and z-: 17. Below j, the effect becomes extremely large when the ly/Ta value is greater than or equal to O0S. In general, regardless of the value of work r, l
The effect is large when the y/T-a value is greater than i, o.Although the explanation has been given on the case where the notch is cut out over the entire part facing the salient pole of the area, the present invention is not limited to this in any way. For example, it is also recommended that a notch be provided only in the vicinity of the intermediate region in contact with the magnetized region, and that no notch be provided in the center of the intermediate region. Such a configuration is particularly advantageous when molding with a plastic magnet or the like.

As described above in detail, the present invention provides a high-quality motor with little cogging and large torque by simply providing a ring-shaped magnet with an intermediate region having a notch. Therefore, it is of extremely great industrial value.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of an inner rotor type motor which is an example of the motor of the present invention, and Figures 2 and 3 are torque (cogging force) versus rotation angle ψ of the motor of the present invention.
The diagrams showing the characteristics, Figures 1 and 5, are diagrams showing the relationship between the absolute value of the maximum torque of the motor of the present invention shown in Figures 2 and 3, and the magnetization angle θ of the magnet, respectively. FIG. 6 is a diagram showing the relationship between the relative size of the notch (it/La) and the maximum torque. l: Core 2: Ring magnet 3: Magnetic yoke //: Salient pole! /: N pole 2λ: S pole 23: Intermediate region 2≠: Notch Patent applicant Mitsubishi Chemical Industries, Ltd. and 7 other representatives Attorney Patent attorney For quality - 7 others 1 Figure 2 Figure 3 Figure Akira 4 Figure 1 Foot steepness θ (degrees) Figure 5 i Equal θ (skin)

Claims (9)

[Claims] (1) In a motor equipped with a ring-shaped magnet magnetized with multiple poles in the radial direction and a core with salient poles arranged inside or outside the magnet, the magnet is perpendicular to the center axis of the ring. It has a substantially uniform composition in each cross section, and is alternately magnetized into north and south poles with substantially the same width, and each magnetized region is separated by an intermediate region. Each intermediate region has substantially the same width, and the portion facing the salient pole is notched, and the strength of magnetization on the surface of this portion is similar to that of the salient pole of the magnetized region. A motor characterized by having a magnetization strength equal to or weaker than that of the surface of the facing part. (2) The width of each magnetized region above is the magnetized angle (360°
/number of salient poles)×(1.05 to 1.15). (3) The maximum value of the notch in the intermediate region is larger than the gap between the magnet and the salient pole in the thickness direction, or The motor according to item 2. (4) The motor according to claim 1 or 2, wherein the magnetization strength of the intermediate region is 1/2 or less of the magnetization strength of the magnetized region. (5) Claim 4, characterized in that the maximum value of the notch is larger than 1/2 or more of the size of the gap between the magnet and the salient pole in the thickness direction. Motor as described. (6) The number of the salient poles is 3n, and the number of magnetized poles is
2n (where n is a positive integer), the motor according to any one of claims 1 to 5. (7) The motor according to any one of claims 1 to 6, wherein the magnet is a rare earth magnet. (8) The motor according to any one of claims 1 to 7, wherein the magnet is a plastic magnet. (9) The motor according to claim 8, wherein the magnetic powder in the magnetized region is an anisotropic magnet oriented in the radial direction.