JP3730911B2 - DC machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a DC machine having a magnet.
[0002]
[Prior art]
Conventionally, a DC motor having a brush is employed as an automobile wiper motor. Among these, there is a motor using a three-brush motor, a so-called third brush. This type of motor uses the third brush for the purpose of changing the rotational speed of the motor. The main principle is to increase the rotational speed of the motor by reducing the magnetic flux used. Specifically, it is realized simply by providing brushes with different installation positions and changing the energization range of the armature coil by selecting (combining) the brushes.
[0003]
[Problems to be solved by the invention]
By the way, the above configuration is an electric machine that is short-circuited by the brush (third brush) every time the high-speed brush (third brush) straddles adjacent commutator pieces in normal operation (low speed specification) of the motor. A large current instantaneously flows in the direction opposite to the energizing direction due to the induced electromotive force generated in the child coil. In FIG. 12, peaks A2 and B2 indicate instantaneous changes in the coil current flowing in the armature coil. As a result, spark discharge occurs in the brush, which causes electrical noise and brush wear, and causes a rectification failure by the so-called third brush. Therefore, a plurality of combinations of a coil (inductor), a capacitor and the like for preventing noise have been used in the motor drive circuit. This is a problem in reducing the number of parts and cost of the motor.
[0004]
The present invention has been made to solve the above-described problems, and the object thereof is to change the magnetic flux distribution of the magnet so as to eliminate the so-called rectification failure due to the third brush. An object of the present invention is to provide a DC machine that can be reduced.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 is configured such that an armature coil is wound around an armature core having a plurality of teeth provided at equal angular intervals, and the armature coil is connected to a commutator. An armature, a pair of magnets disposed opposite to each other with the armature interposed therebetween, first and second brushes disposed at positions opposed to a central axis of the armature and contacting the commutator segment; In a direct current machine including at least one third brush that is disposed at a predetermined angle from a position where the first and second brushes face each other and contacts the segment, one magnet in the pair of magnets Is provided with a weak magnetic flux part, and the weak magnetic flux part is in a state in which the armature is fed by the first brush and the second brush and rotates, and the third brush is adjacent to the two segments. When starting to short-circuit, it is provided in a place where the tips of the teeth bars in the rotation direction side of the plurality of teeth around which the armature coils connected to both the segments are wound approach the weak magnetic flux portion. In addition, the gist of the present invention is that the third brush is formed with a width corresponding to the rotation direction angle which is a period for short-circuiting both segments.
[0006]
According to a second aspect of the present invention, an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and the armature is sandwiched between the armature coil and the armature. A pair of magnets opposed to each other, first and second brushes arranged in opposed positions with respect to the central axis of the armature, and in contact with the commutator segment; and the first and second brushes In a DC machine that is arranged at a predetermined angle from the facing position and includes at least one third brush that contacts the segment, a weak magnetic flux portion is provided in one of the pair of magnets, When the armature is fed and rotated by the first brush and the second brush and the third brush starts to short-circuit both adjacent segments, the weak magnetic flux portion And a tooth bar rotation direction rear end of the first tooth opposite to the rotation direction of the plurality of teeth around which the armature coil connected to the attachment is wound is provided at a place where the weak magnetic flux portion is reached. The gist is that the three brushes are formed with a width corresponding to an angle in the rotation direction in which both segments are short-circuited.
[0007]
The gist of the invention described in claim 3 is the DC machine according to claim 1 or 2, wherein the weak magnetic flux part is a notch formed by notching an inner surface of the magnet.
[0008]
According to a fourth aspect of the present invention, an armature coil is wound around an armature core having a plurality of teeth provided at equal angular intervals, and the armature coil is connected to a commutator, and the armature is sandwiched between the armature coil and the armature. A pair of magnets opposed to each other, first and second brushes arranged in opposed positions with respect to the central axis of the armature, and in contact with the commutator segment; and the first and second brushes In a DC machine that is arranged at a predetermined angle from the facing position and includes at least one third brush that contacts the segment, one magnet in the pair of magnets is composed of divided pieces, The divided pieces are spaced apart so as to form a gap having a predetermined angular interval between the divided pieces, and the armature is supplied with power by the first brush and the second brush. When the third brush starts to short-circuit both adjacent segments in a rolling state, the teeth bar of the first tooth in the rotation direction of the plurality of teeth wound with the armature coils connected to the two segments is rotated. The gist is that the tip of the direction is provided at a position where the gap reaches the gap, and the third brush is formed at an angular interval corresponding to the rotation direction angle that is a period for short-circuiting both segments. .
[0009]
According to a fifth aspect of the present invention, there is provided an armature in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and the armature is sandwiched between A pair of magnets opposed to each other, first and second brushes arranged in opposed positions with respect to the central axis of the armature, and in contact with the commutator segment; and the first and second brushes In a DC machine that is arranged at a predetermined angle from the facing position and includes at least one third brush that contacts the segment, one magnet in the pair of magnets is composed of divided pieces, The divided pieces are spaced apart so as to form a gap having a predetermined angular interval between the divided pieces, and the armature is supplied with power by the first brush and the second brush. When the third brush starts to short-circuit both adjacent segments in a rolling state, the teeth bar of the first teeth opposite to the rotation direction of the plurality of teeth wound with the armature coils connected to both the segments The gist is that the rear end of the rotation direction is provided at a position where the gap reaches the gap, and the third brush is formed at an angular interval corresponding to the rotation direction angle that is a period for short-circuiting both segments. And
[0010]
(Function)
According to the first to fifth aspects of the present invention, the magnetic flux passing through the armature coil is changed by changing the magnetic flux of the magnet portion used at the moment when the third brush short-circuits both adjacent segments (that is, during rectification). The change is eliminated, the induced electromotive force generated in the armature coil is suppressed, and a severe current change in the reverse direction does not occur.
[0011]
According to invention of Claim 3, in addition to the effect | action of the invention of Claim 1 and 2, the structure of a weak magnetic flux part is simple and can be manufactured easily.
According to the fourth and fifth aspects of the present invention, the gap between the magnets is formed by disposing the divided pieces of the divided magnets apart from each other, so that the manufacture and the arrangement can be simplified.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first embodiment embodying the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a schematic structure of a DC motor (wiper motor) 1 as a DC machine of the present embodiment.
[0013]
As shown in FIG. 1, the wiper motor 1 includes magnets 2 and 3, an armature 4, a commutator 5, and a plurality of brushes 6 to 8.
More specifically, the wiper motor 1 of the present embodiment is a two-pole DC motor, and in the motor housing yoke 9, the two magnets 2 and 3 forming the N pole and the S pole are opposed to each other with the armature 4 interposed therebetween. Has been placed. The armature 4 has an armature core 10 and an armature coil 11 wound around the core 10 and is driven to rotate by supplying a direct current.
[0014]
A plurality of teeth 10a are formed on the armature core 10, and an armature coil 11 is wound around n teeth 10a among them. In the present embodiment, the number of teeth 10 a is twelve, and the teeth 10 a are formed every 30 ° in the circumferential direction of the armature 4. That is, adjacent teeth 10a are 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 11 are similarly wound around every five teeth 10a. That is, the winding method of the winding is distributed winding.
[0015]
The commutator 5 is disposed at one end of the armature 4 and has a plurality of segments 12. In the present embodiment, twelve segments 12 are provided every 30 ° in the circumferential direction. As shown in FIG. 1, the armature coil 11 wound around the five teeth 10a is connected to two segments 12 (for example, segments 12a and 12b) on the side substantially opposite to the five teeth 10a.
[0016]
Further, the plurality of brushes 6 to 8 are arranged in a state of being urged so as to be in sliding contact with the commutator 5. In the present embodiment, three brushes 6 to 8 are disposed. Among them, as shown in FIG. 1, the first and second brushes 6 and 7 as the first and second brushes are arranged in a relationship of 180 degrees apart (opposing), and are used as the third brush. The third brush 8 is disposed so as to form a predetermined angle δ with the first brush 6. In the present embodiment, the angle δ is set to be an acute angle formed in the rotation direction from the first brush 6. Further, the brushes 6 to 8 are connected to the DC power supply circuit 13 through the respective terminals 6a to 8a.
[0017]
More specifically, the DC power supply circuit 13 includes a DC power supply 14 and a changeover switch 15, and the brushes 6 and 8 are connected to positive electrodes of the DC power supply 14 via terminals 6 a and 8 a and a changeover switch 15, respectively. . The second brush 7 is connected to the negative electrode of the DC power supply 14 through the terminal 7a. That is, it is possible to select whether the changeover switch 15 is switched to supply power to the motor 1 via the brushes 6 and 7 or to supply power to the motor 1 via the brushes 7 and 8 depending on the operating state.
[0018]
In the present embodiment, in the case of normal operation (low speed specification), the changeover switch 15 is switched so that power is supplied to the motor 1 via the brushes 6 and 7, and in the case of high speed operation, the motor 1 is supplied with power via the brushes 7 and 8. The changeover switch 15 is changed over. That is, the brushes 6 and 7 are arranged at the first position for low-speed rotation, and the brushes 7 and 8 are arranged at the second position for high-speed rotation.
[0019]
When the changeover switch 15 is switched, a DC current supplied from the DC power supply 14 flows to the armature coil 11 through the brushes 6 and 7 or the brushes 7 and 8 and the segment 12 of the commutator 5. As a result, the armature 4 rotates in the clockwise direction (the arrow X direction in the figure).
[0020]
The magnets 2 and 3 are armatures with a predetermined length (for example, as shown in FIG. 1, a length corresponding to an open angle (4θ = 120 °) that is an integral multiple of the motor armature slot angle θ). It is formed so as to be point-symmetric with respect to the central axis of 4.
[0021]
As shown in FIGS. 1 and 2, the magnet 2 is provided with a notch portion 2 a as a weak magnetic flux portion. In the present embodiment, the cutout portion 2 a is provided at a predetermined location near the rotation direction side end portion of the magnet 2. As shown in FIG. 1, when the third brush 8 starts to short-circuit both the segments 12a and 12b while the armature 4 is rotating, the predetermined location is that the armature coil 11 connected to the both segments 12a and 12b The distal ends of the first teeth 10a in the rotational direction of the five teeth 10a to be wound are set at positions where the tips of the teeth bars in the rotational direction come to approach the notches 2a. Further, the notch 2a is formed with a width corresponding to an angle θ1 in the rotational direction that is a period in which the third brush 8 short-circuits both the segments 12a and 12b.
[0022]
FIG. 3 shows changes in the current flowing through the armature coil 11 connected to both segments 12 when the third brush 8 short-circuits both adjacent segments 12 in a state where power is supplied by the brushes 6 and 7 (normal operation). Show. In the present embodiment, as shown in FIG. 1, when the armature 4 rotates in the clockwise direction in a state where power is supplied by the brushes 6 and 7 (normal operation), the third brush 8 short-circuits both adjacent segments 12. When starting, the teeth bar rotation direction front-end | tip of the rotation direction side 1st teeth 10a of the five teeth 10a around which the armature coil 11 connected to the said both segments 12 is wound approaches the said notch part 2a. In other words, during the normal operation, when the tips of the first teeth 10a in the rotation direction of the five teeth 10a around which the armature coils 11 are wound approach the notch portion 2a, the armature coils Both segments 12 to which 11 is connected start to be short-circuited by the third brush 8. In normal operation of the motor 1 fed by the brushes 6 and 7, when the third brush 8 short-circuits both adjacent segments 12a and 12b, the teeth around which the armature coil 11 connected to both segments 12a and 12b is wound Since 10a reaches the notch 2a with a small magnetic flux, the induced electromotive force generated in the armature coil 11 is suppressed as compared with the conventional case. As a result, as shown in FIG. 3, the peak current A1 and the peak B1 are shown in the coil current flowing in the armature coil 11, but the reverse intense current as shown by the peak A2 and the peak B2 in FIG. No change will occur.
[0023]
As described above, according to the present embodiment, it has the following characteristics.
(1) The magnet 2 is provided with a notch 2a. When the third brush 8 starts to short-circuit both the segments 12a and 12b while the armature 4 is rotating, the cutout portion 2a is wound around the armature coil 11 connected to the segments 12a and 12b. The teeth 10a of the first teeth 10a in the rotation direction side of the teeth 10a are provided at locations where the tips of the teeth bars in the rotation direction come to reach the notches 2a. Further, the notch 2a was formed with a width corresponding to the rotation direction angle θ1, which is a period in which the third brush 8 short-circuits both the segments 12a and 12b.
[0024]
Accordingly, since the change in magnetic flux is reduced at the moment when the third brush 8 short-circuits both adjacent segments 12, the induced electromotive force generated in the armature coil 11 is suppressed as compared with the conventional case, and the current changes in the opposite direction are severe. Will not happen.
[0025]
As a result, spark discharge at the third brush 8 is prevented, and electric noise of the motor 1 and brush wear can be reduced. Thereby, it is not necessary to combine a plurality of coils (inductors), capacitors and the like for preventing noise in the drive circuit of the motor 1, and the number of parts and the cost of the motor 1 can be reduced.
[0026]
(2) Since the magnet 2 is provided with the notch portion 2a, the rectification failure due to the third brush can be reduced, which is easy to manufacture and advantageous in terms of cost.
(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a partial cross-sectional view showing a schematic structure of the DC motor 21 of the present embodiment.
[0027]
As illustrated in FIG. 4, the DC motor 21 includes magnets 22 and 23, an armature 24, a commutator 25, and a plurality of brushes 26 to 28.
More specifically, the DC motor 21 of the present embodiment is a two-pole DC motor, and two magnets 22 and 23 forming an N pole and an S pole sandwich an armature 24 in a motor housing yoke 29. Opposed. The armature 24 has an armature core 30 and an armature coil 31 wound around the core 30 and is driven to rotate by supplying a direct current.
[0028]
A plurality of teeth 30a are formed on the armature core 30, and an armature coil 31 is wound around the n teeth 30a. In the present embodiment, the number of the teeth 30 a is twelve, and the teeth 30 a are formed every 30 ° in the circumferential direction of the armature 24. That is, the adjacent teeth 30a are formed such that the angle (motor armature slot angle) θ formed by the center line thereof is 30 ° (= 360 ° / 12). Although not shown, a plurality of armature coils 31 are similarly wound around every five teeth 30a. That is, the winding method of the winding is distributed winding.
[0029]
The commutator 25 is disposed at one end of the armature 24 and has a plurality of segments 32. In the present embodiment, twelve segments 32 are provided every 30 ° in the circumferential direction. As shown in FIG. 4, the armature coil 31 wound around the five teeth 30a is connected to two segments 32 (for example, segments 32a and 32b) on the five teeth 30a side.
[0030]
Further, the plurality of brushes 26 to 28 are arranged in a state of being biased so as to be in sliding contact with the commutator 25. In the present embodiment, three brushes 26 to 28 are disposed. Among them, as shown in FIG. 4, the first and second brushes 26 and 27 as the first and second brushes are arranged in a relationship of 180 degrees apart (opposing), and are used as the third brush. The third brush 28 is disposed so as to form a predetermined angle δ1 with the second brush 27. Further, although not shown, the brushes 26 to 28 are connected to a DC power supply circuit via respective terminals.
[0031]
The magnets 22 and 23 are armatures with a predetermined length (for example, as shown in FIG. 4, a length corresponding to an open angle (5θ = 150 °) that is an integral multiple of the motor armature slot angle θ). It is formed so as to be point-symmetric with respect to the central axis of 24.
[0032]
As shown in FIG. 4, the magnet 22 is provided with a notch portion 22 a as a weak magnetic flux portion. In the present embodiment, the notch 22 a is provided at a predetermined location near the rotation direction opposite end of the magnet 22. As shown in FIG. 4, when the third brush 28 starts to short-circuit both the segments 32a and 32b while the armature 24 is rotating, the predetermined location is that the armature coil 31 connected to both the segments 32a and 32b The tip of the first teeth 30a in the rotation direction of the five teeth 30a to be wound is set at a position where the tips of the teeth bars in the rotation direction come to approach the notches 22a. The notch 22a is formed with a width corresponding to an angle θ1 in the rotational direction that is a period in which the third brush 28 short-circuits both the segments 32a and 32b.
[0033]
FIG. 5 shows a change in induced voltage generated in the armature coil 31 while the armature 24 rotates from the A (0 °) position shown in FIG. 4 to the B (180 °) position. In the present embodiment, during normal operation, when the tips of the first teeth 30a in the rotation direction of the five teeth 30a around which the armature coils 31 are wound approach the notch portion 22a, Both segments 32 to which the child coil 31 is connected start to be short-circuited by the third brush 28. That is, the armature 24 short-circuits both segments 32a and 32b adjacent to the third brush 28 at a position rotated by about 90 ° while rotating from the A (0 °) position to the B (180 °) position shown in FIG. start. Correspondingly, as shown in FIG. 5, when the armature 24 rotates about 90 ° while rotating from the A (0 °) position to the B (180 °) position shown in FIG. The induced voltage generated inside becomes almost zero.
[0034]
As described above, according to the present embodiment, substantially the same effects as those of the first embodiment can be obtained.
(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a partial cross-sectional view showing a schematic structure of the DC motor 41 of the present embodiment. Note that this embodiment is different from the second embodiment in that the magnet provided with the weak magnetic flux portion is different, and for the sake of convenience of explanation, the detailed description of the configuration of the same DC motor is omitted. Only the portions to be described will be described in detail.
[0035]
As shown in FIG. 6, the magnet 43 located on the opposite side of the rotation direction of the brush 48 with respect to the third brush 48 as the third brush is provided with a notch portion 43 a as a weak magnetic flux portion. . The notch 43 a is provided at a predetermined location near the rotation direction side end of the magnet 43. When the third brush 48 starts to short-circuit both the segments 52a and 52b while the armature 44 is rotating, the predetermined place includes five teeth around which the armature coil 51 connected to the segments 52a and 52b is wound. The rear end of the first teeth 50a in the rotation direction opposite to the rotation direction of the teeth 50a is set at a position where the rear end in the rotation direction of the teeth bar reaches the notch 43a. Further, the notch 43a is formed with a width corresponding to an angle θ1 in the rotation direction that is a period in which the third brush 48 short-circuits both the segments 52a and 52b.
[0036]
FIG. 7 shows changes in the induced voltage generated in the armature coil 51 while the armature 44 rotates from the A (0 °) position shown in FIG. 6 to the B (180 °) position. In the present embodiment, in the normal operation of the motor 41 fed by the brushes 46 and 47, the first teeth on the reverse side in the rotational direction of the five teeth 50a around which the armature coils 51 connected to the segments 52a and 52b are wound. When the rear end of the teeth bar rotating direction of 50a approaches the notch 43a, the third brush 48 starts to short-circuit both adjacent segments 52a and 52b. That is, the armature 44 short-circuits both adjacent segments 52a and 52b at the position where the third brush 48 is rotated by about 90 ° while rotating from the A (0 °) position to the B (180 °) position shown in FIG. start. Correspondingly, as shown in FIG. 7, when the armature 44 rotates about 90 ° while rotating from the A (0 °) position to the B (180 °) position shown in FIG. The induced voltage generated inside becomes almost zero.
[0037]
As described above, according to the present embodiment, substantially the same effects as those of the first and second embodiments can be obtained.
In addition, you may implement each said embodiment in the following aspects.
[0038]
In each of the above embodiments, the weak magnetic flux portion may be implemented by a notch portion 62b formed by notching the side surface 62a of the magnet 62 as shown in FIG. Moreover, you may implement a weak magnetic flux part in the through-hole 72a formed through the magnet 72, as shown in FIG. In this case, it is possible to obtain substantially the same effect as in the above embodiments.
[0039]
In addition, the first embodiment may be implemented as shown in FIG. More specifically, the magnet 82 is composed of two divided pieces 82a and 82b. The two divided pieces 82a and 82b are arranged so as to form a gap 82c between the two divided pieces 82a and 82b at a predetermined angular interval θ1. When the armature 4 is fed with the first brush 6 and the second brush 7 and rotates, the third brush 8 starts to short-circuit both adjacent segments 12a and 12b. The tips of the first teeth 10a in the rotation direction of the five teeth 10a around which the armature coils 11 connected to 12b are wound are provided at positions where the tips of the teeth bars in the rotation direction come into contact with the gaps 82c. The angular interval θ1 of the gap 82c is set to be the same as the rotation direction angle that is a period during which the third brush 8 short-circuits both the segments 12a and 12b. In this case, the effects of the first embodiment can be obtained, and the gap 82c of the magnet 82 is formed by arranging the divided pieces 82a and 82b of the divided magnet 82 apart from each other. Easy to place. In addition, although description and drawing are abbreviate | omitted, you may form the weak magnetic flux part of 2nd and 3rd embodiment with the same structure.
[0040]
In the first embodiment, the third brush 8 is arranged to form an acute angle with the first brush 6 on the rotation direction side, and the notch portion 2a is provided at a position close to the rotation direction side end of the magnet 2. Carried out. On the other hand, the third brush 8 is arranged so as to form an obtuse angle on the rotation direction side with the first brush 6, and the notch portion 2a is provided at a position close to the counter rotation direction side end portion of the magnet 2. Also good. Although not shown, the third brush 8 may be arranged to form an obtuse angle or an obtuse angle on the side opposite to the first brush 6 and the magnet 3 may be provided with a notch as a weak magnetic flux portion. Good. In this case, the same effect as the first embodiment can be obtained. Note that the second and third embodiments may be modified based on the same idea.
[0041]
As shown in FIG. 11, the magnet 92 may be implemented by forming a weak magnetic flux portion 92 a by the strength of magnetization. In this case, it is possible to obtain the same effects as in the above embodiments and other examples, and to ensure the rigidity of the magnet 92.
[0042]
In the first embodiment, the magnet may be formed with a length other than the length corresponding to the open angle (4θ = 120 °) that is an integral multiple of the motor armature slot angle θ. In the second and third embodiments, the magnet may be formed with a length other than the length corresponding to the open angle (5θ = 150 °) that is an integral multiple of the motor armature slot angle θ.
[0043]
○ A plurality of third brushes may be provided.
The present invention may be embodied in a motor provided with a plurality of teeth other than twelve teeth. You may implement n teeth other than five in which the same armature coil is wound.
[0044]
In the first embodiment, the DC motor is embodied in the wiper motor 1, but the DC motor may be embodied in other DC motors other than the wiper motor 1.
Next, the technical ideas that can be grasped from the above embodiments and other examples will be described below.
[0045]
(1) An armature coil in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair opposed to each other with the armature interposed therebetween. The first and second brushes that are disposed at opposing positions with respect to the central axis of the armature and are in contact with the commutator segments, and a predetermined angle from the opposing positions of the first and second brushes. And a wiper motor provided with at least one third brush that is disposed in contact with the segment, wherein one magnet of the pair of magnets is provided with a weak magnetic flux portion, and the weak magnetic flux portion When the third brush starts to short-circuit both adjacent segments while the child is powered and rotated by the first brush and the second brush, it is connected to the two segments. The teeth of the first teeth in the direction of rotation of the plurality of teeth around which the armature coils are wound is provided at a location where the tips of the teeth bars come into contact with the weak magnetic flux portion. A wiper motor having a width corresponding to an angle in a rotational direction that is a period for short-circuiting a segment.
[0046]
Therefore, the commutation failure due to the third brush can be removed, and the number of parts and the cost of the wiper motor can be reduced.
(2) An armature in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair disposed opposite to each other with the armature interposed therebetween. The first and second brushes that are disposed at opposing positions with respect to the central axis of the armature and are in contact with the commutator segments, and a predetermined angle from the opposing positions of the first and second brushes. And a wiper motor having at least one third brush arranged and in contact with the segment, wherein one magnet of the pair of magnets is divided into divided pieces, and the divided pieces are divided into the divided pieces. The gap is arranged so as to form a gap having a predetermined angular interval therebetween, and the gap is in a state where the armature is fed by the first brush and the second brush and is rotated. When the third brush starts to short-circuit both adjacent segments, the tips of the teeth bars in the rotation direction side of the plurality of teeth around which the armature coils connected to the segments are wound A wiper motor, characterized in that the wiper motor is provided at a position where the gap comes into contact with the gap, and the third brush is formed at an angular interval corresponding to an angle in a rotational direction that is a period for short-circuiting both segments.
[0047]
Therefore, the commutation failure due to the third brush can be removed, and the number of parts and the cost of the wiper motor can be reduced.
[0048]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to remove the rectification failure due to the third brush, and it is possible to reduce the number of parts and the cost of the DC machine.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a schematic configuration of a DC motor according to a first embodiment.
FIG. 2 is a perspective view of a magnet provided with a weak magnetic flux part according to the first embodiment.
FIG. 3 is a graph showing a change in coil current flowing in the armature coil of the first embodiment.
FIG. 4 is a partial cross-sectional view showing a schematic configuration of a DC motor according to a second embodiment.
FIG. 5 is a graph showing a change in induced voltage generated in the armature coil of the second embodiment.
FIG. 6 is a partial cross-sectional view showing a schematic configuration of a DC motor according to a third embodiment.
FIG. 7 is a graph showing a change in induced voltage generated in the armature coil of the third embodiment.
FIG. 8 is a perspective view of a magnet provided with another weak magnetic flux part.
FIG. 9 is a perspective view of a magnet provided with another weak magnetic flux portion.
FIG. 10 is a partial cross-sectional view showing a schematic configuration of another example of a DC motor.
FIG. 11 is a front view of a magnet in which another example of a weak magnetic flux portion is formed.
FIG. 12 is a graph showing changes in coil current flowing in a conventional armature coil.
[Explanation of symbols]
1, 2, 41, 81... DC motor as DC machine, 2, 3, 22, 23, 42, 43, 62, 72, 82, 92... Magnet, 2a, 22a, 43a, 62b, 72a. Notches, 82a, 82b ... divided pieces constituting the magnet, 82c ... gaps between the divided pieces 82a, 82b constituting the magnet, 4, 24, 44 ... armature, 5, 25, 45 ... commutator, 6, 26, 46 ... first brush as a first brush, 7, 27, 47 ... second brush as a second brush, 8, 28, 48 ... third brush as a third brush, 10, 30, 50 ... Armature core, 10a, 30a, 50a ... Teeth, 11, 31, 51 ... Armature coil, 12, 32, 52 ... Segment.

Claims (5)

An armature coil in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair of magnets arranged opposite to each other with the armature sandwiched therebetween The first and second brushes that are disposed at positions opposed to the central axis of the armature and that are in contact with the commutator segments, and are disposed at a predetermined angle from the positions at which the first and second brushes are opposed. And a DC machine comprising at least one third brush in contact with the segment,
One magnet of the pair of magnets is provided with a weak magnetic flux portion, and the weak magnetic flux portion is supplied with the first brush and the second brush and rotated with the third armature. When the brush starts to short-circuit both adjacent segments, the tips of the first teeth in the rotation direction side of the plurality of teeth around which the armature coils connected to the two segments are wound are the weak magnetic flux portions. A direct current machine characterized in that the DC brush is provided at a place where it comes close and is formed with a width corresponding to an angle in the rotation direction in which the third brush is short-circuited between the segments. An armature coil in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair of magnets arranged opposite to each other with the armature sandwiched therebetween The first and second brushes that are disposed at positions opposed to the central axis of the armature and that are in contact with the commutator segments, and are disposed at a predetermined angle from the positions at which the first and second brushes are opposed. And a DC machine comprising at least one third brush in contact with the segment,
One magnet of the pair of magnets is provided with a weak magnetic flux portion, and the weak magnetic flux portion is supplied with the first brush and the second brush and rotated with the third armature. When the brush starts to short-circuit both adjacent segments, the rear end in the teeth bar rotating direction of the first tooth opposite to the rotating direction of the plurality of teeth wound with the armature coil connected to the two segments is the weak magnetic flux. A direct current machine characterized in that the third brush is formed with a width corresponding to an angle in a rotational direction that is a period for short-circuiting both segments. In the DC machine according to claim 1 or 2,
The DC machine according to claim 1, wherein the weak magnetic flux portion is a cutout portion formed by cutting out an inner surface of the magnet. An armature coil in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair of magnets arranged opposite to each other with the armature sandwiched therebetween The first and second brushes that are disposed at positions opposed to the central axis of the armature and that are in contact with the commutator segments, and are disposed at a predetermined angle from the positions at which the first and second brushes are opposed. And a DC machine comprising at least one third brush in contact with the segment,
One magnet of the pair of magnets is composed of divided pieces, and the divided pieces are spaced apart so as to form a gap having a predetermined angular interval between the divided pieces, the gap being the armature. When the third brush starts to short-circuit both adjacent segments while being fed by the first brush and the second brush and rotated, an armature coil connected to both the segments is wound. The teeth teeth in the rotation direction side of the plurality of teeth are provided at the positions where the tips of the teeth bars in the rotation direction come into contact with the gaps, and the rotation angle becomes the period during which the third brush shorts both segments. A direct current machine characterized by being formed at corresponding angular intervals. An armature coil in which an armature coil is wound around an armature core having a plurality of teeth provided at equiangular intervals, and the armature coil is connected to a commutator, and a pair of magnets arranged opposite to each other with the armature sandwiched therebetween The first and second brushes that are disposed at positions opposed to the central axis of the armature and that are in contact with the commutator segments, and are disposed at a predetermined angle from the positions at which the first and second brushes are opposed. And a DC machine comprising at least one third brush in contact with the segment,
One magnet of the pair of magnets is composed of divided pieces, and the divided pieces are spaced apart so as to form a gap having a predetermined angular interval between the divided pieces, the gap being the armature. When the third brush starts to short-circuit both adjacent segments while being fed by the first brush and the second brush and rotated, an armature coil connected to both the segments is wound. Rotation direction in which the third brush is in a period in which both segments are short-circuited while being provided at a position where the rear end of the teeth bar in the rotation direction opposite to the plurality of teeth reaches the gap. A direct current machine characterized by being formed at an angular interval corresponding to an angle.

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