JPH0550980U - Small motor - Google Patents

Abstract

(57) [Abstract] [Purpose] Saturate magnetization of the magnet to obtain stable magnetizing performance, suppress the deterioration of cogging characteristics due to the magnetizing performance, and further, without increasing the number of parts during assembly. Provide a small motor that is easy to assemble and inexpensive. [Arrangement] When the number of magnetic poles of the magnet 1 is A, the number of poles of the armature core 6 is B, and the greatest common divisor of A and B is C, the angle θ = {C / (A × B) is displayed on the motor case 7. } The magnet 1 having the defect portion 5 and the non-magnetized portion 4 with a tolerance of ± 10% at 360 ° was fixed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a small motor, and more particularly to a magnet thereof.

[0002]

[Prior Art]

 An example of a conventional small motor will be described with reference to the drawings. In FIG. 10, a cylindrical magnet 31 is attached to the inner peripheral surface of a cylindrical motor case 30. The magnet 31 is magnetized with N and S poles in the circumferential direction. A rotating shaft 37 is supported at the center of the cylindrical motor case 30. The armature core 34 is supported on the rotating shaft 37. The armature core 34 has a plurality of salient poles 32, and a coil 33 is wound around each salient pole 32.

In such a small motor, when the magnet 31 is saturated and magnetized, the change in magnetic flux is large when the armature core 37 is rotated, so that cogging becomes large and hinders smooth rotation. Therefore, in order to reduce the cogging and smoothly rotate the magnet 31, the magnet 31 is unsaturatedly magnetized and the change in the magnetic flux when the armature core 37 is rotated is made gentle. By the way, when the magnet 31 is magnetized in a sinusoidal shape, the cogging reduction effect is most effective.

Further, in the example of FIG. 11, two saturated arc-shaped partial arc-shaped magnets 35 and 36 are fixed to opposing positions on the inner peripheral surface of the motor case 30. The magnets 35 and 36 are saturated and magnetized, and cogging is reduced by adjusting the central angle of the magnets 35 and 36 and the angle of the portion where the magnets 35 and 36 are not attached. By the way, in the example of FIG. 11, each magnet 35, 36 has one magnetic pole, and the motor as a whole has a two-pole structure. The center angle of each magnet 35, 36 is 120 °, Cogging is reduced by setting the angles of the defective portions to 60 °.

[0005]

[Problems to be solved by the device]

 According to the conventional small-sized motor shown in FIG. 10, when the magnet 31 is unsaturatedly magnetized in order to reduce the cogging, it is difficult to control the magnetization, and even if the magnetization voltage and the capacity are controlled, Instability due to unsaturated magnetization cannot be overcome. Moreover, since the magnet 31 is unsaturatedly magnetized, sufficient torque of the motor cannot be secured.

According to the small motor shown in FIG. 11 in which the cogging is reduced, since the magnets 35 and 36 are saturated and magnetized, it is easier to manage the magnetization as compared with the example of FIG. Although it has the advantage of ensuring a high motor torque, one magnet is required for each magnetic pole, so the assembly process is more expensive and the cost is higher than when using a cylindrical magnet.

The present invention has been made in order to solve the above problems, and it is possible to achieve saturation magnetization and obtain stable magnetization performance, and to suppress deterioration of cogging characteristics due to it. Further, it is an object of the present invention to provide an inexpensive small-sized motor which is easy to assemble without increasing the number of parts at the time of assembly and can reduce the volume of the magnet.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is such that, when the number of magnetic poles of a magnet is A, the number of poles of an armature core is B, and the greatest common divisor of A and B is C, an angle θ = {C / It is characterized in that a magnet having a defect portion and an unmagnetized portion having a tolerance of ± 10% at (A × B)} × 360 ° is fixed.

[0009]

[Action]

 By using a magnet with a saturated magnetized part with an appropriate angle, a non-magnetized part and a defective part as a magnet for driving the motor, cogging at the time of rotation is reduced, sufficient torque is secured, assembly cost is reduced, etc. Is possible.

[0010]

【Example】

 An embodiment of a small motor according to the present invention will be described below with reference to the drawings. In FIG. 1, a magnet 1 is fixed to the inner peripheral surface of a cylindrical motor case 7. The magnet 1 is not a perfect cylinder, but has a C shape with a part of the circle missing. The C-shaped magnet 1 is saturated and magnetized at two locations facing each other, and the central angle of the magnetized portion is 120 ° from the end of the C-shape. In addition, the C-shaped magnet 1 has a 60 ° unmagnetized portion 4 in the central portion thereof, and a portion facing the unmagnetized portion 4 has a missing portion 5 having the same angle as the unmagnetized portion 4 (the angle is 60 °). A rotating shaft 8 is supported at the center of the inside of the motor case 7, and an armature core 6 is fixed to the rotating shaft 8. The armature core 6 has a plurality of salient poles 2, and a coil 3 is wound around each salient pole 2. The salient pole 2 of the armature core 6 faces the inner peripheral surface of the magnet 1 with a gap.

The surface magnetic distribution waveform of the magnet 1 in FIG. 1 is a substantially rectangular waveform as shown in FIG. Such a square magnetized distribution waveform is obtained by uniformly saturable magnetizing the magnet 1. There is a non-magnetized portion 4 between the two magnetized portions, which suppresses abrupt changes in magnetic flux due to rotation of the armature core 6 and reduces cogging.

FIG. 5 shows that when the magnet 1 according to the embodiment of the present invention has two magnetic poles and the armature core 6 has three magnetic poles, the magnetized portions from both ends of the magnet 1 are saturated so as to be substantially uniform. The graph shows changes in cogging when the angle of the defective portion 5 and the angle of the non-magnetized portion 4 of the magnet 1 are changed from 30 ° to 90 ° under magnetizing conditions. As is clear from the figure, cogging is minimized when the angle of the unmagnetized portion is 60 °. Therefore, in the example of FIG. 1, the angle between the non-magnetized portion 4 and the defective portion 5 is set to 60 °.

From the results of FIG. 5, the number of magnetic poles of the magnet is A, the number of poles of the core is B, and the greatest common divisor of A and B is C, and the angles of the defective portions of the C-shaped magnet are θ and C-shaped. Assuming that the angle of the non-magnetized portion of the magnet is θ ′, θ = θ ′ = {C / (A × B)} × 360 ° (1) holds. By applying the angle guided by the equation (1) to the non-magnetized portion 4 and the defective portion 5, a motor with the least cogging can be obtained.

In the example of FIG. 1, since the number of magnetic poles is 2 and the number of poles of the core is 3, when these values are applied to the above equation, θ = θ ′ = (1 / (2 × 3)) × It becomes 360 ° = 60 °, and it is derived from the mathematical expression in FIG. 1 that the cogging becomes minimum when the angle of the defective portion 5 and the non-magnetized portion 4 is 60 °. However, the angle of the defect portion and the non-magnetized portion for obtaining the target characteristic is not strictly limited to 60 °, and if the target characteristic is within the tolerance of ± 10%. can get.

2 and 3 compare the characteristics of the conventional small motor and the small motor according to the embodiment of the present invention. 2A and 2B show cogging characteristics, FIG. 2A showing a conventional example and FIG. 2B showing an example of the present invention, showing the cogging characteristics when the driving torques are made equal. As is clear from comparison between (a) and (b), it is understood that the embodiment of the present invention has more stable torque and thus has better cogging characteristics.

FIG. 3 shows characteristics of N (rotation speed) -T (torque) -I (current) in comparison with the conventional example and the above-described embodiment of the present invention. The conventional example, (b) is the case of the embodiment of the present invention. Since the conventional example (a) is unsaturated magnetization, the drive torque characteristic is low. To improve the drive torque characteristic, the unsaturated magnetization, which is taken as a measure against cogging, must be abolished. In the example (b), it is understood that the driving torque characteristic is sufficient because one magnet is used and saturated magnetization is performed.

When the C-shaped magnet 1 as shown in FIG. 1 is attached to the motor case, it is necessary to perform accurate positioning in order to suppress variations in motor characteristics and ensure maximum torque. 7 to 9 show means for accurately attaching the magnet. In the example of FIG. 7, protruding portions 19 used for positioning the magnet are provided at two locations on the inner peripheral side of the cylindrical motor case 18, and both protruding portions 19 are brought into contact with both ends of the C-shaped magnet 1. By this, the magnet 1 can be accurately attached to the motor case 18. When the magnet 1 is attached to the motor case 18, the magnet 1 is attached while rounding the shape along the inner circumference of the motor case 18. Therefore, the material of the magnet 1 is a flat plate, a flexible plastic magnet or a bond. A magnet or the like is preferable.

In the examples shown in FIGS. 8 and 9, a part of the brush holder 20 fixed to the inner bottom portion of the bottomed cylindrical motor case 21 is raised to serve as the positioning portion 20 a of the magnet 1. By attaching both ends of the magnet 1 curled in a C shape to the positioning portion 20a in contact with each other, the magnet 1 can be accurately attached to the motor case 20. In this case as well, the material of the magnet 1 is preferably a flat plate-shaped flexible plastic magnet or bond magnet.

Although the example in which the number of magnetic poles is two and the number of poles of the armature core is three has been described above, the invention is not limited to this. For example, the number of magnetic poles of the magnet is four and the number of magnetic poles of the core is four. The number of poles may be six. An example of this is shown in FIG. In FIG. 6, two partially arcuate magnets 13 and 14 are fixed to the inner peripheral surface of a cylindrical motor case 7 at positions facing each other. The two magnets 13 and 14 are not in contact with each other, and the defect portions 11 and 12 having a certain angle (30 ° in this case) are provided between the two magnets 13 and 14. ing. The magnets 13 and 14 have two magnetic poles (angle of 60 °) at both ends and one unmagnetized portion 13a and 14a (angle of 30 °) in the center. Therefore, by using a total of two magnets 13 and 14, four magnetic poles are provided.

A rotating shaft 8 is supported by a motor case 7 at the center of the inside of the magnets 13 and 14, and an armature core 17 having six salient poles 15 is fixed to the rotating shaft 8. Each salient pole 15 coil 3 of the child core 17 is wound. As described above, when the number of magnetic poles is 4 and the number of poles of the armature core is 6, the angle θ of the missing portions 11 and 12 of the magnets and the angle θ of the unmagnetized portions 13a and 14a are expressed by the formula (1). Therefore, θ = θ ′ = {2 / (4 × 6)} × 360 = 30 °. Therefore, when the number of magnetic poles is 4 and the number of poles of the armature core 17 is 6, a small motor with high cogging characteristics can be obtained when the angles of the defective portions 11 and 12 and the non-magnetized portions 13a and 14a are 30 °. Also in this case, the angles θ and θ ′ may be within the tolerance of ± 10 °.

In the embodiment shown in FIG. 6, it is necessary to fix the two magnets 13 and 14 to the motor case, but a magnet having such a four-pole structure is used as in the conventional example shown in FIG. When trying to fix to the motor case, four magnets are fixed to the motor case. Therefore, the embodiment shown in FIG. 6 is superior in assembling workability.

Although the two magnets 13 and 14 are used in the example of FIG. 6, a C-shaped magnet having one loss portion is used, and unmagnetized portions are provided at three places. Alternatively, if the angle between the missing portion and the non-magnetized portion is 30 °, the same effect as in the example of FIG. 1 can be obtained.

[0023]

[Effect of the device]

 According to the present invention, the magnet of the small motor is not formed in a perfect ring shape but is provided with a defective portion and a saturated magnetized portion and a non-magnetized portion are provided. It is possible to obtain a small motor having characteristics. Further, since the number of magnets used for a plurality of magnetic poles is smaller than in the conventional case, the work efficiency at the time of assembly can be improved.

[Submission date] October 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Hereinafter, an embodiment of a small motor according to the present invention will be described with reference to the drawings. In FIG. 1, a magnet 1 is fixed to the inner peripheral surface of a cylindrical motor case 7. The magnet 1 is not a perfect cylinder, but has a C shape with a part of the circle missing. The C-shaped magnet 1 is saturated and magnetized at two locations facing each other, and the central angle of the magnetized portion is 120 ° from the end of the C-shape. Also has a non-arrival magnet part 4 of 60 ° in the center of the C shape magnet 1, a portion facing the non-arrival magnet portion 4 is cut portion 5 (an angle of the same angle as the arrive magnet part 4 60 °). A rotating shaft 8 is supported at the center of the inside of the motor case 7, and the armature core 6 is fixed to the rotating shaft 8. The armature core 6 has a plurality of salient poles 2, and a coil 3 is wound around each salient pole 2. The salient poles 2 of the armature core 6 face the inner peripheral surface of the magnet 1 with a gap.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

In the examples shown in FIGS. 8 and 9, a part of the brush holder 20 fixed to the inner bottom portion of the bottomed cylindrical motor case 21 is raised to serve as the positioning portion 20 a of the magnet 1. By attaching both ends of the magnet 1 curled in a C shape to the positioning portion 20a in contact with each other, the magnet 1 can be accurately attached to the motor case 21 . In this case as well, the material of the magnet 1 is preferably a flat plate-shaped flexible plastic magnet or bond magnet.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

A rotating shaft 8 is supported by a motor case 7 at the center of the inside of the magnets 13 and 14, and an armature core 17 having six salient poles 15 is fixed to the rotating shaft 8. The coil 3 is wound around each salient pole 15 of the child core 17. As described above, when the number of magnetic poles is 4 and the number of poles of the armature core is 6, the angle θ of the missing portions 11 and 12 of the magnet and the angle θ ′ of the non-magnetized portions 13a and 14a are expressed by the formula (1). Therefore, θ = θ ′ = {2 / (4 × 6)} × 360 = 30 °. Therefore, when the number of magnetic poles is 4 and the number of poles of the armature core 17 is 6, a small motor with high cogging characteristics can be obtained when the angles of the defective portions 11 and 12 and the non-magnetized portions 13a and 14a are 30 °. Also in this case, the angles θ and θ ′ may be within the tolerance of ± 10 % .

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a small motor according to the present invention.

FIG. 2 is a characteristic diagram comparing the cogging characteristics of the embodiment and the conventional example.

FIG. 3 is a characteristic diagram comparing the N-T-I characteristics of the above-described example and the conventional example.

FIG. 4 is a waveform diagram showing the surface axis distribution of a magnet that is saturated and magnetized.

FIG. 5 is a waveform diagram showing changes in cogging with respect to angles of a magnetized portion and a non-magnetized portion in the above embodiment.

FIG. 6 is a front sectional view showing another embodiment of the small motor according to the present invention.

FIG. 7 is a front sectional view showing an example of a magnet positioning means applicable to the present invention.

FIG. 8 is a front sectional view showing another example of a magnet positioning means applicable to the present invention.

FIG. 9 is a side sectional view of the same.

FIG. 10 is a sectional view showing an example of a conventional small-sized motor using an unsaturated magnetized magnet.

FIG. 11 is a cross-sectional view showing an example of a conventional small motor using two magnets.

[Explanation of symbols]

 1 Magnet 4 Non-magnetized part 5 Missing part

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[Procedure amendment]

[Submission date] October 19, 1992

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

[Procedure Amendment 6]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

Claims (1)

[Scope of utility model registration request] 1. When the number of magnetic poles of a magnet is A, the number of poles of an armature core is B, and the greatest common divisor of A and B is C, an angle θ = {C / (A × B)} is set in a motor case. A small motor characterized in that a magnet having a defect portion and a non-magnetized portion with a tolerance of ± 10% at × 360 ° is fixed.