JP2002262537A - Dc machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC machine which can assure a smooth rotation and reduce a noise level by reducing cogging torque. SOLUTION: The end part in the tooth-bar rotational direction of a first tooth 8a in the rotational direction of five teeth 8a, to which an armature coil 9 is wound, is disposed to thin-wall portions 2c, 3c of magnets 2, 3 when rectification starts. Moreover, a main magnetic pole 2a of the magnet 2 is formed in the length corresponding to 105 deg., so that the end part in the reverse side in the rotational direction of the main magnetic pole 2a is located at the intermediate position of a fifth tooth 8a and a fourth tooth 8a, when the position corresponding to the center line of the first tooth 8a of the five teeth, to which the armature coil 9 is wound during the rectification, is set to the end part in the rotational direction of the main magnetic pole 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC machine having a magnet.

[0002]

2. Description of the Related Art In a DC motor having a brush and a commutator, the direction of a current flowing through a coil is switched (so-called rectification) by the brush and the commutator. In many cases, the switching is suddenly performed at the last point of the switching. A phenomenon (insufficient rectification) has occurred. As a result, spark discharge occurs at the brush, which causes noise and brush wear.

As a countermeasure, a method has been adopted in which the commutation is improved by selecting a position where the installation position of the brush is shifted in a direction opposite to the rotation direction of the rotor with respect to the installation position of the center of the magnet.

However, since the proper position of the brush changes depending on the rotation speed of the motor and the current of the coil, it is difficult to maintain good commutation when the motor load fluctuates and the rotation speed and the current of the coil change. Therefore, an essential response was desired.

Therefore, the applicant of the present application has previously proposed a technique capable of always performing good rectification without being affected by a load (for example, Japanese Patent Application No. 11-270566). In this technique, in the magnet of the motor, the distribution of magnetic flux in the rotation direction of the magnet is devised so that good commutation can be maintained even when the load varies.

[0006]

In such a motor, the position of the brush relative to the minimum magnetic flux portion in the magnetic flux change portion provided partially on the magnet affects rectification, and this positional relationship is inappropriate. When this happens, the generation of sparks becomes so large that rectification cannot be improved. In addition, since the magnet is partially provided with the magnetic flux changing portion, the attraction force generated between the magnet and the armature changes, and the rotation force generated when the armature is rotated without passing an electric current is used. A certain change in idling torque (cogging torque) increases. This is a problem that causes problems such as noise and vibration of the motor.

The present invention has been made to solve the above problems, and a first object of the present invention is to install a brush at an appropriate position with respect to a magnet having a magnetic flux changing portion (weak magnetic flux portion). Another object of the present invention is to provide a DC machine capable of suppressing spark generation.

A second object of the present invention is to provide a DC machine capable of achieving smooth rotation during rotation and reduction of noise by canceling (reducing) cogging torque.

[0009]

In order to solve the above-mentioned problems, an invention according to claim 1 is provided by winding an armature coil around an armature core having a plurality of teeth provided at equal angular intervals. An armature having a main magnetic pole portion and a first weak magnetic flux portion near a boundary between the main magnetic pole portion and the armature. In the DC machine in which the magnetic flux gradually increases in the direction of rotation, the extension is the tooth angle, and the commutator pieces of the commutator are short-circuited with a brush during commutation to reverse the current direction of the armature coil. The gist is that the tips of the teeth bars of the first teeth in the rotation direction of the plurality of teeth on which the armature coils are wound at the start of commutation are arranged in the first weak magnetic flux portion.

According to a second aspect of the present invention, in the DC machine according to the first aspect, the main magnetic pole portion is formed by centering a first tooth center line of n teeth around which an armature coil being rectified is wound. When the position corresponding to the above is located at the rotation direction end of the main magnetic pole portion, the rotation direction opposite end of the main magnetic pole portion is positioned between the nth tooth and the (n-1) th tooth. The gist of the present invention is that it is formed with a length corresponding to a predetermined arc angle.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
The DC machine according to claim 1, wherein the main magnetic pole portion includes the first magnetic pole.
The gist is that a second weak magnetic flux portion is provided in which the magnetic flux gradually increases in a direction opposite to the rotation direction of the armature at a distance of an integral multiple of the teeth angle from the weak magnetic flux portion.

According to a fourth aspect of the present invention, in the DC machine according to the third aspect, the second weak magnetic flux portion is separated from the first weak magnetic flux portion by an integral multiple of the teeth angle to form a main magnetic pole portion. The gist is that one is provided at

According to a fifth aspect of the present invention, in the DC machine according to the third aspect, the second weak magnetic flux portion is separated from the first weak magnetic flux portion by an integral multiple of the teeth angle to form a main magnetic pole portion. It is the gist that a plurality of locations are provided.

The invention according to claim 6 is the invention according to claims 3 to 5
In the DC machine according to any one of the above, the volume of a portion of the main magnetic pole portion that is notched to form the second weak magnetic flux portion is not larger than the volume of the main magnetic pole portion to form the first weak magnetic flux portion. The gist is that the volume is set to be the same as the volume of the part where the inner surface of the extension is cut off from the end.

The invention according to claim 7 is the invention according to claims 2 to 6
In the DC machine according to any one of the above, the position corresponding to the center line of the first tooth of the n teeth around which the armature coil being rectified is wound is the rotation of the main magnetic pole portion. A length corresponding to a predetermined arc angle such that when located at the end on the direction side, the end of the main magnetic pole portion on the opposite side in the rotational direction is located at an intermediate position between the nth tooth and the (n-1) th tooth. The gist is that it was formed in.

The invention described in claim 8 is the invention according to claims 2 to 6
In the DC machine according to any one of the above, the position corresponding to the center line of the first tooth of the n teeth around which the armature coil being rectified is wound is the rotation of the main magnetic pole portion. A length corresponding to a predetermined arc angle such that, when located at the end of the main pole portion, the end of the main pole portion on the opposite side in the rotational direction is located at the tip end of the teeth bar of the nth tooth on the (n-1) th tooth side. The gist is that it was formed in.

The invention according to claim 9 is the invention according to claims 2 to 6
In the DC machine according to any one of the above, the position corresponding to the center line of the first tooth of the n teeth around which the armature coil being rectified is wound is the rotation of the main magnetic pole portion. A length corresponding to a predetermined arc angle such that when positioned at the end on the direction side, the end on the opposite side in the rotation direction of the main magnetic pole portion is positioned at the tip end of the (n-1) th tooth bar on the nth tooth side. The gist is that it was formed in.

According to a tenth aspect of the present invention, in the DC machine according to any one of the first to ninth aspects, the contact width corresponding to the angle between the connecting pieces and the contact width between the brush and the connecting pieces. The gist is that the angle is set to the same value as the angle between the teeth.

According to an eleventh aspect of the present invention, in the DC machine according to any one of the first to tenth aspects, two magnets are provided so as to face each other with the armature interposed therebetween, and the two magnets are The point is that it is formed point-symmetrically with respect to the armature center axis.

(Operation) According to the first to eleventh aspects of the present invention, the brush is installed at an appropriate position with respect to the magnet having the weak magnetic flux portion. Further, by canceling (reducing) the cogging torque, smooth rotation during rotation and reduction of noise can be achieved.

According to the third aspect of the invention, the cogging torque generated by providing the second weak magnetic flux portion during commutation of the armature coil is offset by the cogging torque generated by the first weak magnetic flux portion.

According to the invention described in claim 4, according to claim 3,
In addition to the operation of the invention described in (1), if the second weak magnetic flux portion is formed in the same shape as the first weak magnetic flux portion, the volume ratio between the two can be easily set without calculation.

According to the invention of claim 5, according to claim 3,
In addition to the effect of the invention described in (1), since the change in magnetic flux of each of the second weak magnetic flux portions can be reduced, the imbalance in the generation of magnetism in the main magnetic pole portion is reduced.

According to the invention of claim 6, according to claim 3,
In addition to the functions of the inventions described in (1) to (5), the cogging torque generated by providing the second weak magnetic flux portion is completely canceled by the cogging torque generated by the first weak magnetic flux portion.

According to the tenth aspect, at the start of commutation, the tips of the teeth bars of the rotation direction side teeth of the n teeth on which the armature coils are wound are securely arranged in the weak magnetic flux portion.

According to the eleventh aspect of the present invention, in addition to the effects of the first to tenth aspects, the generation of magnetism of the DC machine is maintained in a well-balanced manner.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is embodied in a blower motor as a DC machine will be described below with reference to the drawings. FIG. 1 is a partial sectional view showing a schematic structure of a blower motor 1 as a DC machine according to the present embodiment. FIG. 2 shows the blower motor 1 at the start of commutation.
It is a fragmentary sectional view showing the schematic structure of.

As shown in FIGS. 1 and 2, the blower motor 1 includes magnets 2 and 3, an armature 4, and a commutator 5.
And a brush 6. More specifically, the blower motor 1 of the present embodiment is a two-pole DC motor, and two magnets 2 and 3 forming an N pole and an S pole are opposed to each other with an armature 4 interposed in a motor housing yoke 7. Are located. The armature 4 has an armature core 8 and an armature coil 9 wound around the core 8, and is driven to rotate by supplying a DC current.

A plurality of teeth 8a are formed on the armature core 8, and an armature coil 9 is wound around n teeth 8a. In the present embodiment, the number of the teeth 8 a is 12, and the teeth 8 a are formed at every 30 ° in the circumferential direction of the armature 4. That is, the angle between the center lines (motor armature slot angle) θ of the adjacent teeth 8a is 30 ° (= 3
60 ° / 12). Although not shown, a plurality of armature coils 9 are similarly wound around the five teeth 8a. That is, the winding method of the winding is distributed winding.

The commutator 5 is provided at one end of the armature 4 and has a plurality of segments (commit pieces) 5a. Further, the brush 6 is disposed in a state of being urged so as to slide on the commutator 5. Then, when a DC current supplied from a DC power supply (not shown) flows into the armature coil 9 via the brush 6 and the segment 5a of the commutator 5, the armature 4 starts rotating. Then, a pair of adjacent segments 5 a comes into contact with any of the brushes 6, and a short circuit occurs between the segments 5 a via the brush 6, so that the direction of the current flowing through the armature coil 9 is changed. , The armature 4 keeps rotating in the clockwise direction (the X arrow direction in the figure). In the present embodiment, twelve segments 5 a are provided at every 30 ° in the circumferential direction, and the armature 4
When rotating by 0 °, the direction of the current of the armature coil 9 during rectification is changed. That is, the armature coil 9 is rectified by the rotation of the armature 4 by 30 °. In this embodiment, the angle between the segments 5a is set to be the same as the angle θ between the teeth 8a, and the contact width angle corresponding to the contact width between the brush 6 and the segment 5a is the same as the angle θ between the teeth 8a. Is set to

The magnets 2 and 3 are composed of main magnetic pole portions 2a,
3a and extension portions 2b, 3b, and the main magnetic pole portions 2a, 3a
Are extended portions 2 on the rotation direction side of the main magnetic pole portions 2a and 3a.
b, 3b are formed. In other words, magnets 2 and 3
The extension portions 2b, 3b are formed to extend at the ends on the rotation direction side in FIG.

As shown in FIG. 1, the main magnetic pole portions 2a and 3a are formed to have a length corresponding to the arc angle δ. The arc angle δ is referred to as the motor armature slot angle θ.
Δ = θ × {n−1− (1/2)}.
That is, in the present embodiment, the main magnetic pole portions 2a and 3a are represented by θ ×
{N-1− (1/2)} (= 30 ° × {5-1− (1 /
2) 長 = 105 °). The positions corresponding to the center lines of the first teeth 8a of the five teeth 8a around which the armature coil 9 being rectified is wound are the rotation direction side ends of the main magnetic pole portions 2a and 3a (that is, the main magnetic pole portions 2a and 3a When located at the boundary between the extensions 2b and 3b), the ends of the main magnetic poles 2a and 3a on the opposite side in the rotation direction are located at an intermediate position between the fifth tooth 8a and the fourth tooth 8a.

As shown in FIG. 1, the extension portions 2b and 3b have a motor armature slot angle (that is, an angle of a commutation section).
It is formed to have a length corresponding to θ (= 30 °) so that the thickness gradually increases in the rotation direction. That is, the magnets 2 and 3 have their main magnetic pole portions 2a and 3a and the extension portions 2b and 3b.
Thin portions 2c and 3c as first weak magnetic flux portions near the boundary with
Are formed. And the magnetized magnet 2,
Numeral 3 has a minimum magnetic flux density at the boundary between the main magnetic pole portions 2a, 3a and the extension portions 2b, 3b, and the magnetic flux density changes along the thin portions 2c, 3c of the extension portions 2b, 3b.

Here, the positional relationship between the armature core 8 (five teeth 8a) wound by the armature coil 9 and the magnets 2 and 3 during rectification will be described with reference to FIG. Since the magnets 2 and 3 are arranged symmetrically with respect to the center of the armature, only the positional relationship between the armature core 8 (five teeth 8a) and the magnet 2 will be described for convenience of description.

As shown in FIG. 2, when the armature 4 rotates and the core tip of the armature core 8 (ie, the tip of the teeth bar of the first teeth 8a) is located at the thin portion 2c of the magnet 2, one segment is formed. The brush 6 that is in contact with 5a starts to contact with another adjacent segment 5a, and commutation of the armature coil 9 is started. In other words, at the moment when the brush 6 enters the commutation state, the core end of the armature core 8 (that is, the end of the teeth bar of the first teeth 8a) comes to approach the thin portion 2c of the magnet 2.

The position where the armature 4 is rotated clockwise at a predetermined angle from the rotational position in FIG. 2 is the commutation center (the rotational position in FIG. 1), and the direction of the current flowing through the armature coil 9 at this position. Is in a state of being reversed. At this time, the end of the main magnetic pole portion 2a in the rotation direction is located at a position corresponding to the center line of the first teeth 8a, and the end of the main magnetic pole portion 2a opposite to the rotation direction is connected to the fifth teeth 8a. It is located at an intermediate position between the fourth teeth 8a (a gap position between the teeth). Further, the commutation is completed at a rotational position where the armature 4 is rotated clockwise at a predetermined angle from this state (the rotational position in FIG. 1).

During this rectification, the extension 2b facing the tip of the armature core 8 is formed so as to be gradually thicker at a portion corresponding to a 30 ° angle of the rectification section. Therefore, the amount of magnetic flux passing through the armature coil 9 during rectification gradually increases in accordance with the rotation of the armature 4. At this time,
The rate of increase in the amount of magnetic flux gradually increases with rotation. As described above, since the amount of magnetic flux passing through the armature coil 9 during the commutation changes, the induced voltage generated in the armature coil 9 is small at the initial stage of commutation and gradually decreases to the negative side according to the rotational position of the armature 4. Become larger. And, by this induced voltage,
The reactance voltage is canceled and the under-commutation is improved.

FIG. 3 shows the idling torque T when the armature 4 of this embodiment is rotated by one slot (30 °) from the position (0 °) at the start of commutation of the armature coil 9.
(Cogging torque ΔT1). In the present embodiment, when commutation of the armature coil 9 is started, the end of the main magnetic pole portion 2a on the opposite side in the rotation direction is located at an intermediate position between the fifth teeth 8a and the fourth teeth 8a (a gap position between the teeth).
, The cogging torque ΔT1 decreases as shown in FIG. This cogging torque ΔT1 is
It is about 8.3% lower than the cogging torque of the prior art.

As described above, this embodiment has the following features. (1) At the start of commutation, the tips of the teeth bars of the first teeth 8a on the rotation direction of the n teeth 8a around which the armature coil 9 is wound approach (dispose) the first weak magnetic flux portion 2c. In other words, the first teeth 8 on the rotation direction of the n teeth 8a around which the armature coil 9 is wound.
a when the tip of the teeth bar approaches the first weak magnetic flux portion 2c, the two segments 5a to which the armature coil 9 is connected.
The position of the brush 6 was set so that the brush 6 was short-circuited by the brush 6.

Therefore, since the brush 6 is set at an appropriate position with respect to the magnet 2 having the first weak magnetic flux portion 2c,
Rectification is performed well, and generation of sparks can be suppressed. (2) The main magnetic pole portions 2a, 3a are formed with a length corresponding to the predetermined arc angle δ. The predetermined arc angle δ is determined by the five teeth 8a around which the armature coil 9 being rectified is wound.
When the position corresponding to the center line of the first tooth 8a is located at the end in the rotation direction of the main magnetic pole portions 2a, 3a, the end opposite to the rotation direction of the main magnetic pole portions 2a, 3a is connected to the fifth tooth 8a. It is set to be located at an intermediate position between the four teeth 8a.

Therefore, when commutation of the armature coil 9 is started, the ends of the main magnetic pole portions 2a and 3a on the opposite side in the rotation direction are furthest away from the center line position of the fifth tooth 8a on which the armature coil 9 is wound. As a result, the cogging torque ΔT1 of the blower motor 1 can be greatly reduced as compared with the related art. As a result, smooth rotation and reduction of noise during rotation of the motor can be achieved.

(3) Main magnetic pole part 2 of magnets 2 and 3
The cogging torque can be reduced by changing the lengths of a and 3a, which is easy to manufacture and advantageous in cost. (4) The angle between the segments 5a is the angle θ between the teeth 8a.
And the contact width angle corresponding to the contact width between the brush 6 and the segment 5a is set to be the same as the angle θ between the teeth 8a.

Therefore, the rotation direction side teeth 8a of the five teeth 8a around which the armature coil 9 is wound at the start of commutation.
The tips of the teeth bars of the magnets 2 and 3 are thin portions 2c,
3c. In other words, commutation is reliably started when the tips of the teeth bars of the rotation-direction teeth 8a of the five teeth 8a around which the armature coil 9 is wound are located at the thin portions 2c, 3c of the magnets 2, 3. become.

(Second Embodiment) Hereinafter, a second embodiment in which the present invention is embodied in a blower motor as a DC machine will be described with reference to the drawings. FIG. 4 is a partial cross-sectional view illustrating a schematic structure of a blower motor 11 as a DC machine according to the present embodiment. FIG. 5 is a partial sectional view showing a schematic structure of the blower motor 11 at the start of commutation.

As shown in FIGS. 4 and 5, the blower motor 11 has magnets 12 and 13, an armature 14, a commutator 15, and a brush 16. To elaborate,
The blower motor 11 of the present embodiment is a two-pole DC motor, and two magnets 12 and 13 forming an N pole and an S pole are arranged to face each other across an armature 14 in a motor housing yoke 17. . The two magnets 12 and 13 are formed point-symmetrically with respect to the central axis of the armature 14. The armature 14 includes an armature core 18 and the core 18
And an armature coil 19 wound therearound, and is driven to rotate by supplying a DC current.

The armature core 18 includes a plurality of teeth 18
a are formed, of which n teeth 18a
, An armature coil 19 is wound therearound. In the present embodiment, the number of the teeth 18a is 12, and the number of the teeth 18a is three in the circumferential direction of the armature 14.
It is formed every 0 °. In other words, adjacent teeth 1
8a is formed such that an angle (motor armature slot angle) θ formed by the center line thereof is 30 ° (= 360 ° / 12). Although not shown, a plurality of armature coils 19 are similarly wound around the five teeth 18a. That is, the winding method of the winding is distributed winding.

The commutator 15 is provided at one end of the armature 14 and has a plurality of segments 15a. Further, the brush 16 is disposed in a state where the brush 16 is urged so as to slide on the commutator 15. And
When a DC current supplied from a DC power supply (not shown) flows into the armature coil 19 via the brush 16 and the segment 15a of the commutator 15, the armature 14 starts rotating. Then, a pair of adjacent segments 15a comes into contact with any of the brushes 16 and short-circuits between the segments 15a via the brushes 16, whereby the direction of the current flowing through the armature coil 19 is changed. , The armature 14 continues to rotate in the counterclockwise direction (the direction of the arrow Y in the figure). In the present embodiment, twelve segments 15a are provided every 30 ° in the circumferential direction, and when the armature 14 rotates 30 ° in the commutation section with respect to the brush 16, the current of the armature coil 19 during commutation is changed. Is changed. That is, the armature coil 1 is rotated by 30 ° of the armature 14.
Nine rectifications are performed. In the present embodiment, the angle between the segments 15a is set to be the same as the angle θ between the teeth 18a, and the contact width angle corresponding to the contact width between the brush 16 and the segment 15a is the same as the angle θ between the teeth 18a. Is set to

The magnets 12 and 13 are provided with the main magnetic pole portion 1.
The main magnetic pole portions 12a, 13a have extended portions 12b, 13b on the rotation direction side of the main magnetic pole portions 12a, 13a. That is, the extension portions 12b and 13b are formed to extend at the ends of the magnets 12 and 13 on the rotation direction side.

As shown in FIG. 4, the main magnetic pole portions 12a and 13a have a length corresponding to an opening angle (4θ = 120 °) which is an integral multiple of the motor armature slot angle θ. Although not shown, when the position corresponding to the center line of the first tooth 18a of the five teeth 18a around which the armature coil 19 is wound is located at the rotation direction side ends of the main magnetic pole portions 12a and 13a, The ends of the magnetic pole portions 12a and 13a on the opposite side in the rotation direction are located at positions corresponding to the center line of the fifth teeth 18a. 4, when the intermediate position between the first tooth 18a and the immediately preceding tooth 18a is located at the rotation direction side end of the main magnetic pole portions 12a, 13a, the rotation direction of the main magnetic pole portions 12a, 13a is determined. The opposite end is located at an intermediate position between the fifth tooth 18a and the fourth tooth 18a.

As shown in FIG. 4, the extension portions 12b and 13b are provided at the motor armature slot angle (that is, the angle of the commutation section).
It is formed to have a length corresponding to θ (= 30 °) so that the thickness gradually increases in the rotation direction. That is, magnet 1
The main poles 12a, 13a and the extension 12
The first thin portions 12c and 13c as first weak magnetic flux portions are formed at the boundaries between the first thin portions 12c and 13c.

The main magnetic pole portions 12a and 13a have:
Second thin portions 12d and 13d as second weak magnetic flux portions are provided at an angle (mθ) that is an integral multiple of the motor armature slot angle θ from the rotation direction side ends of the main magnetic pole portions 12a and 13a. In the present embodiment, as shown in FIG. 4, the second thin portions 12d and 13d are formed at a distance of 2θ (= 60 °) in the clockwise direction from the rotation-side ends of the main magnetic pole portions 12a and 13a. . As shown in FIG. 4, when the intermediate position between the first tooth 18a and the immediately preceding tooth 18a is located at the first thin portions 12c, 13c, the second teeth are located at the second thin portions 12d, 13d. An intermediate position between the first teeth 18a and the third teeth 18a is located.

The second thin portions 12d and 13d are
The first thin portions 12c, 13c in the motor rotation direction.
It is formed symmetrically in reverse shape. In other words,
The second thin portions 12d and 13d and the first thin portions 12c and 13c
The thickness changes in the rotation direction are opposite. That is, the first thin portions 12c and 13c gradually increase in thickness in the rotation direction (the magnetic flux gradually increases),
The thin portions 12d and 13d gradually become thicker in the anti-rotation direction (the magnetic flux gradually increases). In the present embodiment, the first thin portions 12c, 13c are formed by the main magnetic pole portions 12a, 1a.
If the portion near the boundary between the extension 3a and the extension portions 12b, 13b is cut out, the second thin portions 12d, 13
The volume of the cutout portion for forming d is set to be the same as the volume of the cutout portion for forming the first thin portions 12c and 13c.

Here, the armature core 18 (five teeth 18a) wound by the armature coil 19 during rectification.
The positional relationship between the magnets 12 and 13 will be described with reference to FIG. Since the magnet 12 and the magnet 13 are arranged symmetrically with respect to the armature center, only the positional relationship between the armature core 18 (five teeth 18a) and the magnet 12 will be described for convenience of description.

As shown in FIG. 5, the armature 14 rotates and the tip of the armature core 18 (that is, the first teeth 18a
Is the thin portion 12c of the magnet 12
When approaching, the brush 16 abutting on one segment 15a begins to abut another adjacent segment 15a. That is, commutation of the armature coil 19 starts.
In other words, the moment the brush 16 enters the commutation state, the tip of the core of the armature core 18 (that is, the tip of the teeth bar of the first teeth 18a on the side opposite to the second teeth 18a) comes to reach the thin portion 12c of the magnet 12. At this time, the tip of the teeth bar of the third tooth 18a on the side of the second tooth 18a comes to reach the thin portion 12d of the magnet 12.

When the armature 14 rotates counterclockwise from the rotational position shown in FIG. 5, the direction of the current flowing through the armature coil 19 is reversed. During this commutation, the extension 12b facing the tip of the armature core 18 is formed so as to be gradually thicker at a portion corresponding to a 30 ° angle of the commutation section. Therefore, the amount of magnetic flux passing through the armature coil 19 during rectification gradually increases in accordance with the rotation of the armature 14. At this time, the rate of increase in the amount of magnetic flux gradually increases in accordance with the rotation. Thus, the commutating armature coil 19
, The induced voltage generated in the armature coil 19 is small at the initial stage of the commutation and gradually increases to the negative side according to the rotational position of the armature 14. Then, the induced voltage cancels out the reactance voltage, and the insufficient rectification is improved.

FIG. 6 shows a change (cogging) in the idling torque T when the armature 14 of the present embodiment rotates by one slot (θ) from the position (assumed to be 0 °) at the start of commutation of the armature coil 19. Torque). In FIG. 6, a change in the idling torque T caused by the presence of the first thin portions 12c and 13c is indicated by a two-dot chain line A1, and a change in the idling torque T caused by providing the second thin portions 12d and 13d is indicated by a solid line A2. Shown. The motor commutation is performed within the rotation angle θ (= 30 °) of the motor, and the second thin portion 12d, 1
3d is an angle mθ from the first thin portions 12c, 13c.
(M is an integer), the change periods of the two-dot chain line A1 and the solid line A2 are both rotation angles θ.
(= 30 °). Also, the second thin portions 12d, 1
The solid line A2 and the two-dot chain line A1 are sinusoidal curves that change in opposite directions because 3d and the first thin portions 12c and 13c are symmetrically formed in opposite directions in the motor rotation direction. . The change in the idling torque T (cogging torque) caused by the presence of the first thin portions 12c and 13c and the change (cogging torque) in the idling torque T caused by providing the second thin portions 12d and 13d are as follows.
They have a mutually canceling relationship. As a result, the total cogging torque applied to the motor 11 becomes substantially zero.

As described above, this embodiment has the following features. (1) The first thin portion 12 is provided on the main magnetic pole portions 12a and 13a.
c and 13c, the second thin portions 12d and 13d are separated by an angle mθ (m = 2) that is an integral multiple of the motor armature slot angle θ.
Was provided. The change in the thickness of the second thin portions 12d, 13d in the rotation direction is opposite to that of the first thin portions 12c, 13c.

Accordingly, when commutating the armature coil 19, the cogging torque which cancels the cogging torque generated by the presence of the first thin portions 12c, 13c is applied to the second thin portions 12d, 12d.
This is caused by providing 13d. As a result, the cogging torque of the motor 11 can be reduced, and smooth rotation and noise reduction during motor rotation can be achieved.

(2) The volume of the notch for forming the second thin portions 12d, 13d is the first thin portion 12c,
The volume is set to be the same as the volume of the cutout portion for forming 13c. Therefore, the cogging torque caused by the presence of the first thin portions 12c and 13c and the second thin portion 12
d and 13d have the same magnitude as the cogging torque generated by the provision of the motors 11 and 13d.
Is almost zero. As a result, smooth rotation and noise reduction during motor rotation can be reliably achieved.

(3) By providing the second thin portions 12d, 13d on the main magnetic pole portions 12a, 13a of the magnets 12, 13, the cogging torque can be reduced.
It is easy to manufacture and advantageous in cost.

(4) The two magnets 12 and 13 which are arranged opposite to each other with the armature 14 interposed therebetween are formed point-symmetrically with respect to the central axis of the armature 14. Therefore, the generation of magnetism of the motor 11 can be maintained in a well-balanced manner.

In this embodiment, the first thin portion 12
c, 13c, the separation angle m between the second thin portions 12d, 13d
θ is the separation angle from the minimum magnetic flux point of the first thin portions 12c, 13c (boundary between the main magnetic pole portions 12a, 13a and the extension portions 12b, 13b) to the minimum magnetic flux point of the second thin portions 12d, 13d.

Each of the above embodiments may be implemented in the following manner. In the first embodiment, as shown in FIG. 7, the main magnetic pole portions 22a and 23a constituting the magnets 22 and 23
Is given by a predetermined arc angle δ1 (= θ × {n−1− (1/2)}}.
+ T / 2 = 30 ° × {5-1- (1/2)} + t / 2 =
105 ° + t / 2). Here, t is the opening angle between the tips of both adjacent teeth bars of the adjacent teeth 28a. The first of the five teeth 28a around which the armature coil 29 being rectified is wound
The position corresponding to the center line of the teeth 28a is the main magnetic pole portion 22.
a, 23a, the opposite ends of the main magnetic pole portions 22a, 23a in the rotation direction are the fourth teeth 28.
It is located at the tip of the teeth bar of the fifth tooth 28a on the a side. In this case, when commutation of the armature coil 29 starts, the ends of the main magnetic pole portions 22a and 23a on the opposite side in the rotation direction are connected to the armature coil
9 is located away from the center line of the fifth tooth 28a on which the coil 9 is wound, so that the cogging torque of the blower motor 21 can be reduced, and smooth rotation and noise reduction during motor rotation can be achieved.

In the first embodiment, as shown in FIG. 8, the main magnetic pole portion 32 forming the magnets 32 and 33
a, 33a are converted to a predetermined arc angle δ2 (= θ × ｛n−1−
(1/2)｝-t / 2 = 30 ° × ｛5-1- (1 /
2) It may be formed with a length corresponding to｝ −t / 2 = 105 ° −t / 2). Here, t is adjacent teeth 38
a is the opening angle between the tips of both adjacent teeth bars. When the positions corresponding to the center lines of the first teeth 38a of the five teeth 38a around which the armature coil 39 being rectified is wound are located at the rotation direction side ends of the main magnetic pole portions 32a, 33a, The ends of the portions 32a and 33a on the opposite side in the rotation direction are located at the tips of the teeth bars of the fourth teeth 38a on the fifth teeth 38a side. In this case, when commutation of the armature coil 39 is started, the ends of the main magnetic pole portions 32a and 33a on the opposite side in the rotation direction are located away from the center line position of the fifth tooth 38a around which the armature coil 39 is wound. The cogging torque of the blower motor 31 can be reduced, and smooth rotation and reduction of noise when the motor rotates can be achieved.

In the first embodiment, although not shown, the main magnetic pole portion constituting the magnet is set at a predetermined arc angle δ
3 (δ3 ≠ δ, δ2 <δ3 <δ1). When the position corresponding to the center line of the first tooth of the five teeth around which the armature coil being rectified is wound is located at the end in the rotation direction of the main magnetic pole portion, the rotation direction of the main magnetic pole portion is on the opposite side. The end is located at an arbitrary position between the fifth tooth and the fourth tooth except for an intermediate position between the fifth tooth and the fourth tooth. In this case, substantially the same effects as those of the first embodiment and the above-described another example can be obtained.

In the first embodiment and each of the above examples, the thickness of the extension of the magnet is changed in order to increase the amount of synthetic magnetic flux passing through the armature coil during rectification. It is not limited to this. For example,
As shown in FIG. 9, in the magnet 40 having a constant thickness, the magnetization strength of the magnetic dipole at the boundary A between the main magnetic pole portion 40a and the extension portion 40b may be changed to be embodied. Further, as shown in FIG.
In the above, the orientation of the magnetic dipole at the boundary B between the main magnetic pole portion 50a and the extension portion 50b may be changed and embodied.
Further, as shown in FIG. 11, the weakly magnetized material 60d may be embedded in the thin portion 60c between the main magnetic pole portion 60a and the extended portion 60b so as to make the thickness of the magnet 60 uniform. In these cases, effects similar to those of the first embodiment and each of the above alternative examples can be obtained.

In the second embodiment, as shown in FIG. 12, main magnetic pole portions 72a and 73a are provided with thin portions 72e and 73e and thin portions 72f and 73f constituting a second weak magnetic flux portion.
Also, thin portions 72g and 73g may be provided. More specifically, the main magnetic pole portions 72a, 73a are provided with the first thin portion 72.
30 ° (θ) away from the thin portions 72e, 7c
3e, 60 ° (2 °) from the first thin portions 72c, 73c.
θ), the thin portions 72f, 73f, the first thin portion 7
90 ° (3θ) apart from 2c, 73c
g, 73g, and the change in their thickness is
The main magnetic pole portions 72a and 73a are provided with cut-out inner surfaces so as to be opposite to c and 72d. Moreover, the thin portions 72e, 7
3e and thin portions 72f, 73f and thin portions 72g, 73g
The total integral value of the volume of each portion of the main magnetic pole portions 72a and 73a notched to form the second magnetic thin portions 72d and 73d as the second weak magnetic flux portions The volume value is the same. In this case, the thin portion 7
2e, 73e and thin portions 72f, 73f and thin portion 72
The magnitude of the cogging torque by g and 73g is the same as the magnitude of the cogging torque by the first thin portions 72c and 73c, and the directions of generation of the cogging torque at the same rotation angle are opposite to each other.

As a result, substantially the same effects as in the second embodiment can be obtained, and the thin portions 72e and 73e can be obtained.
And the thin portions 72f, 73f and the thin portions 72g, 73g,
Main magnetic pole portions 72a, 7 shallower than first thin portions 72c, 73c
Since the inner surface of 3a is cut away, the rigidity of the entire magnets 72, 73 can be prevented from lowering.

The thin portions 72e, 73e and the thin portion 72
Alternatively, any one of the thin portions f and 73f and the thin portions 72g and 73g may be omitted. In this case, the remaining two thin portions may be formed such that the magnitude of the cogging torque by the two thin portions is the same as the magnitude of the cogging torque by the first thin portions 72c, 73c.

In addition, the second thin portion 12 of the second embodiment
d, 13d, or the thin portions 72e, 73e and the thin portions 72f, 73f and the thin portions 72g, 73g or the two thin portions thereof among the above-described other examples, and the idling torque T due to them.
6 (cogging torque), as shown by the alternate long and short dash line A3 in FIG. 6, the first thin portions 12c (72c) and 13c (73c).
It may be formed to be smaller than the cogging torque according to c). In this case, although the total cogging torque applied to the motor does not become zero due to the cancellation of the two cogging torques, the cogging torque can be reduced.

In the second embodiment, the second thin portion 12
d, 13d are at an angle 2θ from the first thin portions 12c, 13c.
(M = 2) formed on the main magnetic pole portions 12a and 13a apart. On the other hand, the second thin portions 12d and 13d are
An angle of 0 ° (m = 0) or θ from the thin portions 12c, 13c
(M = 1) or 3θ (m = 3) away from the main magnetic pole 12
a, 13a.

In the second embodiment and another example, the second weak magnetic flux portion of the magnet 12 (72) and the magnet 13 (7
The second weak magnetic flux portion 3) was formed at the same angle away from the first weak magnetic flux portion, that is, at the same angle mθ. In contrast, the angle at which the second weak magnetic flux portion of the magnet 12 (72) is separated from the first weak magnetic flux portion of the magnet 12 (72), and the second weak magnetic flux portion of the magnet 13 (73) is The angle apart from the first weak magnetic flux portion may be implemented at a different angle. That is, the second weak magnetic flux portion of the magnet 12 (72) is
When the angle away from the first weak magnetic flux portion is mθ, the second weak magnetic flux portion of the magnet 13 (73)
The angle away from the first weak magnetic flux portion of (73) is defined as m′θ (m ′
≠ m).

Similarly, in the second embodiment, although not shown, the magnets 12 (72), 1 (1) having a constant thickness are not shown.
In 3 (73), the first and second weak magnetic flux portions may be formed by changing the magnetization strength or direction of the magnetic dipole. Further, the first and second weak magnetic flux portions may be formed by burying a weakly magnetized material in the cutout portions so as to make the thicknesses of the magnets 12 (72) and 13 (73) uniform. In this case, substantially the same effects as in the above embodiment can be obtained.

In the second embodiment, the main magnetic pole portion 12a
(72a) and 13a (73a) are formed with a length corresponding to the opening angle (4θ = 120 °) which is an integral multiple of the motor armature slot angle θ. On the other hand, the main magnetic pole part 1
2a (72a) and 13a (73a) may be formed to have a length corresponding to an opening angle that is {n−1− (1/2)} times the motor armature slot angle θ. Here, n is the number of teeth around which the same armature coil is wound. That is, the main magnetic pole portions 12a (72a) and 13a (73a)
{N-1− (1/2)} of motor armature slot angle θ
(= 5-1− (１ ／) = 3.5) times the opening angle (3.5 × 30 ° = 105 °). In this case, the cogging torque generated by each thin portion decreases.

The main magnetic pole portions 12a (72a), 13
a (73a) is expressed as ｛n− of the motor armature slot angle θ.
It may be formed with a length corresponding to an opening angle that is 1- (1/2) ± t / 2 ／ times. Here, n is the number of teeth around which the same armature coil is wound, and t is the opening angle between the tips of both adjacent teeth bars of adjacent teeth.

In each of the above-described embodiments and other examples, the magnet is cut off from the inner surface thereof to form a weak magnetic flux portion to make the magnet thin, but as shown in FIGS.
The weak magnetic flux portion may be formed by hollowing out the magnet from its outer peripheral surface. More specifically, the outer peripheral surface 82 of the magnet 82
A concave portion 82b is formed at a predetermined position of a. The recess 82b
Is formed by hollowing out the magnet 82 from the outer peripheral surface 82a. According to this, when the weak magnetic flux portion (concave portion) 82b is formed by post-processing on the fan-shaped magnet 82, the cutting is performed from the outer peripheral surface 82a, so that the working range of the cutting tool is not limited, and the cutting operation is easy. It is. Also,
Since the weak magnetic flux portion is a concave portion 82b formed by hollowing out the magnet 82 from the outer peripheral surface 82a, the side wall 8 of the magnet 82
By leaving 2c, the strength of the thinned portion can be maintained.

The present invention may be embodied in a motor having a plurality of teeth other than twelve. The same armature coil may be wound around n teeth other than five.

Although the present invention has been embodied in a blower motor as a DC machine, it may be embodied in another motor as a DC machine other than the blower motor. The arc angle described in each of the above embodiments and another example indicates a central angle corresponding to the arc length.

Next, technical ideas that can be grasped from the above embodiments and other examples will be additionally described below. (1) an armature configured by winding an armature coil around an armature core having a plurality of teeth provided at equal angular intervals; and a magnet opposed to the armature with the armature interposed therebetween. The magnet has a main magnetic pole portion and an extension portion having a first weak magnetic flux portion near the boundary between the main magnetic pole portion and the teeth angle at which the magnetic flux gradually increases in the rotation direction of the armature, and is rectified. In a DC machine in which a commutator piece of a commutator is short-circuited with a brush and a current direction of the armature coil is reversed, a tip of a teeth bar of a first tooth on a rotation direction side of n teeth on which an armature coil is wound is provided. A brushless DC machine characterized in that when the brushes are arranged in the first weak magnetic flux portion, the brushes are positioned so that the two segments connected to the armature coil are short-circuited by the brushes.

Therefore, since the brush is set at an appropriate position with respect to the magnet having the first weak magnetic flux portion, rectification is performed favorably and generation of sparks can be suppressed.

[0081]

As described in detail above, according to the present invention,
The cogging torque of the DC machine can be greatly reduced,
Smooth rotation and reduction of noise during rotation of the DC machine can be achieved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a schematic configuration of a DC motor according to a first embodiment.

FIG. 2 is a partial cross-sectional view showing a schematic structure of a DC motor at the start of commutation according to the first embodiment.

FIG. 3 is a graph showing the cogging torque of the DC motor according to the first embodiment.

FIG. 4 is a partial cross-sectional view illustrating a schematic configuration of a DC motor according to a second embodiment.

FIG. 5 is a partial cross-sectional view showing a schematic structure of a DC motor at the start of commutation according to a second embodiment.

FIG. 6 is a graph showing the cogging torque of the DC motor according to the second embodiment.

FIG. 7 is a partial cross-sectional view showing a schematic configuration of another example of a DC motor.

FIG. 8 is a partial sectional view showing a schematic configuration of another example of a DC motor.

FIG. 9 is an explanatory view showing another example of a magnet.

FIG. 10 is an explanatory view showing another example of a magnet.

FIG. 11 is an explanatory view showing another example of a magnet.

FIG. 12 is a partial cross-sectional view showing a schematic configuration of another example of a DC motor.

13A is a perspective view of a main part showing another example of a magnet, FIG.
(B) The principal part top view.

[Explanation of symbols]

1,11,21,31,71 ... Blower motor as DC machine, 2,12,22,32,72,3,13,23,
33, 73 ... magnets, 2a, 12a, 22a, 32
a, 72a, 3a, 13a, 23a, 33a, 73a ...
Main magnetic pole part, 2b, 12b, 22b, 32b, 72b, 3
b, 13b, 23b, 33b, 73b ... extension, 2c,
12c, 22c, 32c, 72c, 3c, 13c, 23
c, 33c, 73c: the first thin portion as the first weak magnetic flux portion, 12d, 72e, 72f, 72g, 13d, 73
e, 73f, 73g: the second thin portion as the second weak magnetic flux portion, 4, 14, 24, 34, 74 ... armature, 5, 15,
25, 35, 75 ... commutator, 5a, 15a, 2
5a, 35a, 75a ... segments as comb pieces,
6, 16, 26, 36, 76 ... brush, 8, 18, 2
8, 38, 78 ... armature core, 8a, 18a, 28a,
38a, 78a: Teeth, 9, 19, 29, 39, 7
9 ... Armature coil.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshihiro Tanino 390 Umeda, Kosai-shi, Shizuoka Prefecture Asmo Co., Ltd. F-term (reference) 5H623 AA03 AA05 BB07 GG13 GG15 GG22 GG28 LL09 LL19

Claims (11)

[Claims] 1. An armature having an armature coil wound around an armature core having a plurality of teeth provided at equal angular intervals, and a magnet opposed to the armature with the armature interposed therebetween. The magnet has a main magnetic pole portion and an extension portion having the first weak magnetic flux portion near a boundary between the main magnetic pole portion and the teeth angle at which the magnetic flux gradually increases in the rotation direction of the armature. In a DC machine in which a commutator piece of a commutator is short-circuited by a brush during commutation and the current direction of the armature coil is reversed, at the start of commutation, the rotation direction side of the plurality of teeth around which the armature coil is wound A DC machine, wherein a tip of a tooth bar of one tooth is arranged in the first weak magnetic flux part. 2. The DC machine according to claim 1, wherein said main magnetic pole portion is wound with an armature coil being rectified.
When the position corresponding to the center line of the first tooth of the plurality of teeth is located at the end in the rotation direction of the main magnetic pole portion, the end of the main magnetic pole portion opposite to the rotation direction is the nth tooth and the (n-th) tooth. 1) A DC machine characterized by being formed with a length corresponding to a predetermined arc angle so as to be located between the teeth. 3. The DC machine according to claim 1, wherein the main magnetic pole portion is away from the first weak magnetic flux portion by an integral multiple of the teeth angle and opposite to the rotation direction of the armature. A DC machine having a second weak magnetic flux portion in which a magnetic flux gradually increases in a direction. 4. The DC machine according to claim 3, wherein the second weak magnetic flux portion is provided at a position on the main magnetic pole portion at an integer multiple of the teeth angle from the first weak magnetic flux portion. Characteristic DC machine. 5. The DC machine according to claim 3, wherein the second weak magnetic flux portion is provided at a plurality of locations on the main magnetic pole portion away from the first weak magnetic flux portion by an integral multiple of the teeth angle. A DC machine characterized by that: 6. The DC machine according to claim 3, wherein a volume of a portion of the main magnetic pole portion in which an inner side surface is cut out to form the second weak magnetic flux portion is the first weak magnetic flux. A DC machine characterized in that the volume is set to be equal to the volume of a portion of the extension extending from the end of the main magnetic pole portion to form an inner surface. 7. The DC machine according to claim 2, wherein said main magnetic pole portion is wound with an armature coil being rectified.
When the position corresponding to the center line of the first tooth of the plurality of teeth is located at the end in the rotation direction of the main magnetic pole portion, the end of the main magnetic pole portion opposite to the rotation direction is the nth tooth and the (n-th) tooth. 1) A DC machine characterized by being formed at a length corresponding to a predetermined arc angle so as to be located at an intermediate position between the teeth. 8. The DC machine according to claim 2, wherein the main magnetic pole portion is wound with an armature coil being rectified.
When the position corresponding to the center line of the first tooth of the plurality of teeth is located at the rotation direction end of the main magnetic pole portion, the rotation direction opposite end of the main magnetic pole portion is positioned at the (n-1) th tooth side. N-th
A DC machine having a length corresponding to a predetermined arc angle so as to be located at a tip end position of a tooth of a tooth. 9. The DC machine according to claim 2, wherein said main magnetic pole portion is wound with an armature coil being rectified.
When the position corresponding to the center line of the first teeth of the first teeth is located at the end in the rotation direction of the main magnetic pole portion, the end of the main magnetic pole portion opposite to the rotation direction in the direction (n) -1)
A DC machine having a length corresponding to a predetermined arc angle so as to be located at a tip end position of a tooth of a tooth. 10. The DC machine according to claim 1, wherein the angle between the joint pieces and the contact width angle corresponding to the contact width between the brush and the comb pieces are the angles between the teeth. DC machine characterized by being set to the same value as. 11. The DC machine according to claim 1, wherein two magnets are provided to face each other with the armature interposed therebetween, and the two magnets are point-symmetric with respect to the armature center axis. DC machine characterized by being formed in.