Motor

Abstract

The present invention reduces the noise of a motor.　Provided is, for example, a motor (1) comprising: a rotor (10) that has first and second slots (S1, S2), a first coil pair (31a, 31b), and a second coil pair (33a, 33b); a commutator (4) that has a first segment pair (C1, C2) and a second segment pair (C3, C4); a brush (7); and a magnet (6) that has first and second regions (61, 62) on a q axis. The first coil pair (31a, 31b), which are connected to the first segment pair (C1, C2), pass through the first slot (S1), and the second coil pair (33a, 33b), which are connected to the second segment pair (C3, C4), pass through the second slot (S2). When the first segment pair (C1, C2) have the same electric potential and the second segment pair (C3, C4) have same electric potential, the first slot (S1) is opposite from the first region (61) and the second slot (S2) is opposite from the second region (62).

Description

Motor

[0001] The present invention relates to a motor.

[0002] In a DC motor having a commutator with multiple segments and brushes in contact with the commutator, noise and vibration can be a problem. For example, Patent Document 1 describes a technology for suppressing noise and vibration using a motor having a pair of coils formed by winding a conductor between any two slots and between two slots radially opposite the first two slots in a series connection.

[0003] Japanese Patent Application Laid-Open No. 2002-305861

[0004] In DC motors, there is still a need to reduce switching noise that occurs when the commutator segments that the brushes come into contact with are switched. The present invention addresses the issue of reducing motor noise, for example.

[0005] A motor that is one example of the present invention comprises a rotor having a plurality of slots including a first slot and a second slot, and a plurality of coils including a first coil pair and a second coil pair, a commutator having a plurality of segments including a first segment pair and a second segment pair, a plurality of brushes in contact with the commutator, and a magnet having a first region and a second region on the q-axis, wherein the first coil pair electrically connected to the first segment pair passes through the first slot, and the second coil pair electrically connected to the second segment pair passes through the second slot, and when the two segments included in the first segment pair are at the same potential and the two segments included in the second segment pair are at the same potential, the first slot faces the first region and the second slot faces the second region.

[0006] Another example of the present invention is a motor comprising: a shaft; a rotor fixed to the shaft; a commutator fixed to the shaft; a plurality of brushes in contact with the commutator; and a magnet having a first region and a second region on the q-axis; the rotor comprising a plurality of slots including a first slot and a second slot; and a plurality of coils including a first coil pair and a second coil pair; the commutator comprising a plurality of segments including a first segment pair and a second segment pair; the first coil pair electrically connected to the first segment pair passes through the first slot; the second coil pair electrically connected to the second segment pair passes through the second slot; of the plurality of brushes, a first brush connects to two segments included in the first segment pair; and a second brush connects to two segments included in the second segment pair; the first slot faces the first region; and the second slot faces the second region.

[0007] FIG. 1 is an exploded perspective view of a motor according to an example of the present invention; FIG. 2 is a schematic diagram showing the arrangement of each element of a motor according to an example of the present invention, as viewed from the commutator side, at a certain point in time; FIG. 3A is a schematic diagram showing the direction of current flowing in conductors passing through each slot in the arrangement shown in FIG. 2A; FIG. 4B is a schematic diagram showing the wiring of a motor according to a first embodiment as an example of the present invention, and the direction of current at a certain point in time; FIG. 5 is a schematic diagram showing the direction of current at a point in time when the rotor has rotated slightly more than the point in time shown in FIG. 3A; FIG. 6 is a schematic diagram showing the wiring of a motor according to a second embodiment as an example of the present invention, and the direction of current at a certain point in time; FIG. 7 is a schematic diagram showing the wiring of a motor according to a third embodiment as an example of the present invention, and the direction of current at a certain point in time; FIG. 8 is a schematic diagram showing the wiring of a motor according to a fourth embodiment as an example of the present invention, and the direction of current at a certain point in time.

[0008] In describing the embodiments of the present invention, for convenience of explanation, the direction along the rotation axis X of the rotor 10 (rotation axis direction) will be simply referred to as the axial direction. A direction approaching or moving away from the rotation axis X in a plane perpendicular to the rotation axis X will be referred to as the radial direction. In the radial direction, the direction away from the rotation axis X (the direction indicated by arrow a in FIG. 1 ) will be referred to as the outer side or one side, and the direction approaching the rotation axis X (the direction indicated by arrow b in FIG. 1 ) will be referred to as the inner side or the other side. A direction rotating around the rotation axis X will be referred to as the circumferential direction. Of the circumferential directions, the clockwise direction (the direction of arrow P) when viewing the rotor 10 from the commutator 4 will be referred to as the first direction P, and the counterclockwise direction (the direction of arrow Q) will be referred to as the second direction Q.

[0009] First, a common configuration among multiple embodiments of the present invention will be described with reference to Fig. 1. Fig. 1 is an exploded perspective view of a motor 1 according to these embodiments. As shown in Fig. 1, the motor 1 includes a rotor 10, a commutator 4, a housing 5, a magnet 6, multiple brushes 7 in contact with the commutator 4, and a shaft 8.

[0010] The rotor 10 includes a rotor core 2 having a plurality of magnetic pole portions and a plurality of conductors 3 wound around the rotor core 2. While the number of magnetic pole portions of the rotor core 2 is eight in FIG. 1 , this is merely an example and other numbers may be used. The number of magnetic pole portions of the rotor core 2 may be, for example, twelve. Although the plurality of conductors 3 are shown in a simplified manner in FIG. 1 , in reality, as will be described later, the plurality of conductors 3 are wound across two or more of the plurality of slots (spaces between two circumferentially adjacent magnetic pole portions) of the rotor 10. The rotor 10 is fixed to the outer peripheral surface (the outer surface in the radial direction) of the shaft 8.

[0011] The commutator 4 is fixed to the outer circumferential surface of the shaft 8 adjacent to the rotor 10. The commutator 4 has a plurality of segments and is electrically connected to a plurality of conductors 3. Although the number of segments of the commutator 4 is four in FIG. 1, this is merely an example and other numbers may be used. The number of segments of the commutator 4 may be, for example, six. The number of segments of the commutator 4 may be N / 2 (N is an even number equal to or greater than eight), where N is the number of slots (= the number of magnetic pole portions) of the rotor 10. The commutator 4, shaft 8, and rotor 10 are rotatable as a unit.

[0012] The housing 5 is a cylindrical member (for example, a three-dimensional shape in which the cross section along the radial direction is circular, rectangular, polygonal, or polygonal with multiple curved corners) and is made of a magnetic material such as iron. The housing 5 accommodates the rotor 10. A cylindrical magnet 6 is fixed to the inner radial surface of the housing 5 (in the direction of arrow b). The housing 5 and the magnet 6 constitute a stator 20.

[0013] The magnet 6 is a permanent magnet having multiple magnetic poles. In the illustrated embodiment, the magnet 6 has a total of two magnetic poles, one north pole and one south pole. The magnet 6 may be a magnet 6 having multiple magnetic poles composed of multiple permanent magnets, or may be a magnet 6 having multiple magnetic poles composed of a single permanent magnet. The magnet 6 is magnetized with two different magnetic poles (north pole and south pole) alternately in the circumferential direction. In each drawing, the boundary between the two different magnetized magnetic poles of the magnet 6 is shown by a solid line. However, in reality, the strict boundary between the two different magnetized magnetic poles of the magnet 6 may not be identified.

[0014] The brushes 7 include a first brush 7a and a second brush 7b. The first brush 7a and the second brush 7b are fixed to the housing 5 and electrically connected to an external power source (not shown). The first brush 7a and the second brush 7b contact the commutator 4 from the radially outer side (in the direction of arrow a) and supply current to the conductors 3 through the segments of the commutator 4. When current is supplied to the conductors 3, magnetic attractive or repulsive forces are generated between the magnet 6 and each magnetic pole portion of the rotor 10, causing the rotor 10 to rotate. When the commutator 4 rotates along with the rotor 10, the first brush 7a and the second brush 7b slide over the surface of the commutator 4, periodically changing the state of electrical connection between each segment of the commutator 4 and the first brush 7a and the second brush 7b. As a result, the magnetic attractive or repulsive forces acting between the magnet 6 and each magnetic pole portion of the rotor 10 also periodically change, causing the rotor 10 to continue rotating.

[0015] First Embodiment A motor 1 according to a first embodiment of the present invention will be described below.

[0016] Fig. 2A is a schematic diagram showing the arrangement of each element at a certain point in time as viewed from the side where the commutator 4 is provided in the motor 1. Fig. 2B is a schematic diagram showing the direction of current flowing axially through the multiple conductors 3 in the arrangement shown in Fig. 2A.

[0017] As shown in FIG. 2A , the rotor 10 has multiple (eight in this embodiment) magnetic pole portions. Hereinafter, any one of the multiple magnetic pole portions of the rotor 10 will be referred to as magnetic pole portion T1, and the magnetic pole portions will be referred to in order from magnetic pole portion T1 toward the first direction P as magnetic pole portions T2, T3, T4, T5, T6, T7, and T8. Each of the multiple conductors 3 is wound across the multiple magnetic pole portions T1 to T8. The dashed arrows on each of the multiple conductors 3 indicate the direction of current at the time shown in FIG. 2A . In FIG. 2A , conductors without dashed arrows are temporarily in a non-conductive state. Note that, in this specification, the term "non-conductive" refers to, for example, currents that inevitably occur due to electromagnetic induction or slight currents that may occur when segments in contact with the same brush are not strictly at the same potential. For example, if the magnitude of the current flowing through a conductor at a given time is 10% or less of the maximum magnitude of the current flowing through that conductor, this specification will treat it as "non-current-carrying."

[0018] 2A, the commutator 4 has a plurality of segments (four in this embodiment) arranged in the circumferential direction. Hereinafter, of the plurality of segments of the commutator 4, the segment that overlaps the magnetic pole portion T1 and the magnetic pole portion T2 in the circumferential direction will be referred to as segment C1, and the segments from segment C1 toward the first direction P will be referred to as segments C2, C3, and C4 in this order.

[0019] Segments C1 to C4 of the commutator 4 are in contact with multiple (two in this embodiment) brushes 7 (first brush 7a and second brush 7b) to allow current to flow. As shown in FIG. 2A, the first brush 7a is in contact with the circumferentially adjacent segments C1 and C2 at the same time, and the second brush 7b is in contact with the circumferentially adjacent segments C3 and C4 at the same time. Hereinafter, segments C1 and C2 may be collectively referred to as the "first segment pair C1, C2," and segments C3 and C4 may be collectively referred to as the "second segment pair C3, C4."

[0020] The first brush 7a and the second brush 7b are arranged symmetrically with respect to the shaft 8. The first brush 7a and the second brush 7b are arranged on the d-axis (see FIG. 2B ) described below, with the first brush 7a on the side where the north pole of the magnet 6 is arranged and the second brush 7b on the side where the south pole of the magnet 6 is arranged. The circumferential dimensions of each of the first brush 7a and the second brush 7b are such that they do not come into contact with three or more adjacent segments at the same time.

[0021] 2B , a plurality of slots are formed between two circumferentially adjacent magnetic pole portions among the plurality of magnetic pole portions T1 to T8 of the rotor 10. For convenience, in this specification, the slot between the magnetic pole portion T8 and the magnetic pole portion T1 will be referred to as the first slot S1, the slot between the magnetic pole portion T4 and the magnetic pole portion T5 as the second slot S2, the slot between the magnetic pole portion T1 and the magnetic pole portion T2 as the third slot S3, the slot between the magnetic pole portion T5 and the magnetic pole portion T6 as the fourth slot S4, the slot between the magnetic pole portion T2 and the magnetic pole portion T3 as the fifth slot S5, the slot between the magnetic pole portion T6 and the magnetic pole portion T7 as the sixth slot S6, the slot between the magnetic pole portion T3 and the magnetic pole portion T4 as the seventh slot S7, and the slot between the magnetic pole portion T7 and the magnetic pole portion T8 as the eighth slot S8.

[0022] The motor 1 has a d-axis and a q-axis depending on the configuration of the magnet 6. The d-axis and q-axis are based on the general definitions for brushed DC motors. As shown in FIG. 2B , when the number of magnetic poles of the magnet 6 is two, the axis along the direction of the magnetic flux from the north pole to the south pole of the magnet 6 (the direction at the center of the motor 1) is the d-axis, and the axis perpendicular to the d-axis is the q-axis. The magnet 6 has a first region 61 and a second region 62 on the q-axis. The first region 61 and the second region 62 may be, for example, regions within a range of ±10° around the q-axis of the magnet 6, or may be regions within a range of ±5° around the q-axis of the magnet 6. The first region 61 and the second region 62 are typically regions where two different magnetic poles (north and south poles) switch positions. However, as described above, the strict boundary between the two different magnetic poles of the magnet 6 does not need to be specified.

[0023] The symbols shown on the multiple conductors 3 schematically shown in Figure 2B indicate the direction of current. An X symbol in a circle indicates that the current flows into the page, i.e., away from the commutator 4 in the axial direction. A double circle symbol indicates that the current flows into the page, i.e., toward the commutator 4 in the axial direction. A black circle symbol indicates that the current is not conducting.

[0024] 2B, that is, when the first brush 7a is in contact with the first segment pair C1, C2 and the second brush 7b is in contact with the second segment pair C3, C4, the first slot S1 faces the first region 61 of the magnet 6 and the second slot S2 faces the second region 62 of the magnet 6. At this time, the conductor 3 passing through the first slot S1 and the second slot S2 is in a non-conductive state.

[0025] FIG. 3A is a schematic diagram showing the wiring of the motor 1 according to this embodiment and the direction of current at the times shown in FIGS. 2A and 2B . In FIG. 3A and subsequent figures, the components arranged circumferentially of the motor 1 are shown expanded in the left-right direction. The rightward direction in the figure corresponds to the first circumferential direction P, and the leftward direction corresponds to the second circumferential direction Q. In FIG. 3A and subsequent figures, the intersections of the solid or dashed lines representing the multiple conductors 3 are not electrically connected. Although the magnet 6 is located radially outside the rotor 10, for convenience, the magnet 6 is shown on the upper side of the rotor 10 in FIG. 3A and subsequent figures. Similarly, although the first brush 7a and the second brush 7b are located radially outside the commutator 4, for convenience, the first brush 7a and the second brush 7b are shown on the lower side of the commutator 4 in FIG. 3A and subsequent figures. In FIG. 3A and subsequent figures, arrows superimposed on the conductors 3 indicate the current direction at that time. In FIG. 3A and the following figures, when a conductor 3 is shown with a dashed line, this indicates that the conductor is not conducting electricity.

[0026] In Figure 3A and subsequent figures, symbols shown above the multiple conductors 3 passing through each slot indicate the direction of current. An X in a circle indicates that the current is flowing in the axial direction away from the commutator 4. A double circle indicates that the current is flowing in the axial direction toward the commutator 4. A black circle indicates that the current is not flowing.

[0027] 3A , the rotor 10 includes a plurality of conductors 3. In this embodiment, the plurality of conductors 3 are configured as a first conductor group 30. The first conductor group 30 includes a first conductor 31, a second conductor 32, a third conductor 33, and a fourth conductor 34. Both ends of each of the first conductor 31, the second conductor 32, the third conductor 33, and the fourth conductor 34 are connected to segments of the commutator 4.

[0028] As shown in Fig. 3A , the first conducting wire 31 connected to the segment C1 via a riser (not shown) is wound across three adjacent magnetic pole portions (magnetic pole portions T1, T2, and T3) of the rotor core 2, i.e., across the first slot S1 and the seventh slot S7, to form the coil 31a. Note that in Fig. 3A , the coil 31a is illustrated as being wound less than once across the three adjacent magnetic pole portions (magnetic pole portions T1, T2, and T3) of the rotor core 2, but the number of windings of the coil 31a is arbitrary and may be less than one as in Fig. 3A , or may be one or more times (the same applies to all coils hereinafter).

[0029] The first conducting wire 31 forming the coil 31a extends to the vicinity of the magnetic pole portion T8 and is wound across three adjacent magnetic pole portions (magnetic pole portions T8, T7, and T6) of the rotor core 2, i.e., across the first slot S1 and the fourth slot S4, to form the coil 31b, which is connected to the segment C2 via a riser (not shown). That is, the first conducting wire 31 forms a plurality of coils (two in this embodiment) wound across three circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T4 and T5) are located between the two coils 31a and 31b formed by one first conducting wire 31.

[0030] The second conducting wire 32, connected to the segment C2 via a riser (not shown), is wound across three adjacent magnetic pole portions (magnetic pole portions T3, T4, and T5) of the rotor core 2, i.e., across the fifth slot S5 and the fourth slot S4, to form the coil 32a. The second conducting wire 32 forming the coil 32a extends to the vicinity of the magnetic pole portion T2 and is wound across three adjacent magnetic pole portions (magnetic pole portions T2, T1, and T8) of the rotor core 2, i.e., across the fifth slot S5 and the eighth slot S8, to form the coil 32b, which is connected to the segment C3 via a riser (not shown). That is, the second conducting wire 32 forms a plurality of coils (two in this embodiment) wound across three circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T6 and T7) are present between the two coils 32a and 32b formed by one second conducting wire 32.

[0031] The third conducting wire 33, connected to the segment C3 via a riser (not shown), is wound across three adjacent magnetic pole portions (magnetic pole portions T5, T6, and T7) of the rotor core 2, i.e., across the second slot S2 and the eighth slot S8, to form the coil 33a. The third conducting wire 33 forming the coil 33a extends to the vicinity of the magnetic pole portion T4, and is wound across three adjacent magnetic pole portions (magnetic pole portions T4, T3, and T2) of the rotor core 2, i.e., across the second slot S2 and the third slot S3, to form the coil 33b, which is connected to the segment C4 via a riser (not shown). That is, the third conducting wire 33 forms a plurality of coils (two in this embodiment) wound across three circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T8 and T1) are present between the two coils 33a and 33b formed by one third conducting wire 33.

[0032] The fourth conducting wire 34, connected to segment C4 via a riser (not shown), is wound across three adjacent magnetic pole portions (magnetic pole portions T7, T8, and T1) of rotor core 2, i.e., across the sixth slot S6 and the third slot S3, to form coil 34a. The fourth conducting wire 34 forming coil 34a extends to the vicinity of magnetic pole portion T6 and is wound across three adjacent magnetic pole portions (magnetic pole portions T6, T5, and T4) of rotor core 2, i.e., across the sixth slot S6 and the seventh slot S7, to form coil 34b, which is connected to segment C1 via a riser (not shown). That is, the fourth conducting wire 34 forms multiple coils (two in this embodiment) wound across three circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T2 and T3) are present between the two coils 34a and 34b formed by one fourth conducting wire 34.

[0033] As described above, the rotor 10 of the motor 1 has multiple coils, each of which is wound across two or more of the multiple slots. In this embodiment, for convenience, the coils 31a and 31b are referred to as the first coil pair 31a, 31b, and the coils 33a and 33b are referred to as the second coil pair 33a, 33b. In this embodiment, the first coil pair 31a, 31b is a series coil formed by a single first conductor 31, and the second coil pair 33a, 33b is a series coil formed by a single third conductor 33. The first coil pair 31a, 31b is electrically connected to the first segment pair C1, C2 and passes through the first slot S1 (the slot between the magnetic pole portions T8 and T1). The second coil pair 33a, 33b is electrically connected to the second segment pair C3, C4 and passes through the second slot S2 (the slot between the magnetic pole portions T4 and T5).

[0034] 3A, the two segments C1 and C2 included in the first segment pair C1, C2 are both in contact with the first brush 7a and therefore have the same potential (equipotential), and the two segments C3 and C4 included in the second segment pair C3, C4 are both in contact with the second brush 7b and therefore have the same potential. The first coil pair 31a, 31b is electrically connected to the first segment pair C1, C2, which has the same potential, and therefore is not conducting electricity. The second coil pair 33a, 33b is electrically connected to the second segment pair C3, C4, which has the same potential, and therefore is not conducting electricity. At this time, the first slot S1 through which the first coil pair 31a, 31b passes faces the first region 61 on the q axis of the magnet 6, and the second slot S2 through which the second coil pair 33a, 33b passes faces the second region 62 on the q axis of the magnet 6.

[0035] In the present embodiment, two adjacent coils share two magnetic pole portions in the motor 1. For example, of the three magnetic pole portions (magnetic pole portions T1, T2, and T3) wound around the coil 31a, the magnetic pole portions T2 and T3 are included in the three magnetic pole portions (magnetic pole portions T2, T3, and T4) wound around the coil 33b adjacent to the coil 31a in the first direction P. Similarly, of the three magnetic pole portions (magnetic pole portions T2, T3, T4) wound around coil 33b, magnetic pole portions T3 and T4 are included in the three magnetic pole portions (magnetic pole portions T3, T4, T5) wound around coil 32a adjacent to coil 33b in the first direction P, of the three magnetic pole portions (magnetic pole portions T3, T4, T5) wound around coil 32a, magnetic pole portions T4 and T5 are included in the three magnetic pole portions (magnetic pole portions T4, T5, T6) wound around coil 34b adjacent to coil 32a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T4, T5, T6) wound around coil 34b, magnetic pole portions T5 and T6 are included in the three magnetic pole portions (magnetic pole portions T5, T6, T7) wound around coil 33a adjacent to coil 34b in the first direction P.

[0036] Furthermore, of the three magnetic pole portions (magnetic pole portions T5, T6, T7) wound around the coil 33a, the magnetic pole portions T6 and T7 are included in the three magnetic pole portions (magnetic pole portions T6, T7, T8) wound around the coil 31b adjacent to the coil 33a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T6, T7, T8) wound around the coil 31b, the magnetic pole portions T7 and T8 are included in the three magnetic pole portions (magnetic pole portions T7, T8, T1) wound around the coil 34a adjacent to the coil 31b in the first direction P. Of the three magnetic pole portions (magnetic pole portions T7, T8, T1) wound around coil 34a, magnetic pole portions T8 and T1 are included in the three magnetic pole portions (magnetic pole portions T8, T1, T2) wound around coil 32b adjacent to coil 34a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T8, T1, T2) wound around coil 32b, magnetic pole portions T1 and T2 are included in the three magnetic pole portions (magnetic pole portions T1, T2, T3) wound around coil 31a adjacent to coil 32b in the first direction P.

[0037] In the present embodiment, three adjacent coils share one magnetic pole portion in the motor 1. For example, the magnetic pole portion T1 is wound around three adjacent coils, namely, the coil 34a, the coil 32b, and the coil 31a. Similarly, magnetic pole portion T2 is wound around three adjacent coils, coil 32b, coil 31a, and coil 33b; magnetic pole portion T3 is wound around three adjacent coils, coil 31a, coil 33b, and coil 32a; magnetic pole portion T4 is wound around three adjacent coils, coil 33b, coil 32a, and coil 34b; magnetic pole portion T5 is wound around three adjacent coils, coil 32a, coil 34b, and coil 33a; magnetic pole portion T6 is wound around three adjacent coils, coil 34b, coil 33a, and coil 31b; magnetic pole portion T7 is wound around three adjacent coils, coil 33a, coil 31b, and coil 34a; and magnetic pole portion T8 is wound around three adjacent coils, coil 31b, coil 34a, and coil 32b.

[0038] In this embodiment, the two connection portions of the first conductor 31 are connected to two different circumferentially adjacent segments (segments C1 and C2) via a riser (not shown). The two connection portions of the second conductor 32 are connected to two different circumferentially adjacent segments (segments C2 and C3) via a riser (not shown). The two connection portions of the third conductor 33 are connected to two different circumferentially adjacent segments (segments C3 and C4) via a riser (not shown). Furthermore, the two connection portions of the fourth conductor 34 are connected to two different circumferentially adjacent segments (segments C4 and C1) via a riser (not shown). Thus, in this embodiment, all of the conductors included in the first conductor group 30 are connected to two different circumferentially adjacent segments.

[0039] At the time shown in Figure 3A, a predetermined DC voltage is applied to the first brush 7a and the second brush 7b. Current flowing from the first brush 7a to segment C1 follows the fourth conductor 34 of the first conductor group 30 through coil 34b and coil 34a, reaches segment C4, and then flows out from the second brush 7b. Current flowing from the first brush 7a to segment C2 follows the second conductor 32 of the first conductor group 30 through coil 32a and coil 32b, reaches segment C3, and then flows out from the second brush 7b. As described above, the first coil pair 31a, 31b is electrically connected to the first segment pair C1, C2, which are at the same potential, and therefore is not conducting. The second coil pair 33a, 33b is electrically connected to the second segment pair C3, C4, which are at the same potential, and therefore is not conducting.

[0040] 3A, a force acts to rotate the rotor 10 and the commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T8 and the segments C1 to C4 move in the first direction P, transitioning to the state shown in FIG.

[0041] 3B, the first brush 7a is in contact only with segment C1, and the second brush 7b is in contact only with segment C3. A portion of the current flowing from the first brush 7a to segment C1 follows the first conductor 31 of the first conductor group 30 through coils 31a and 31b to reach segment C2, then follows the second conductor 32 of the first conductor group 30 through coils 32a and 32b to reach segment C3, and then flows out of the second brush 7b. At the same time, another portion of the current flowing from the first brush 7a to segment C1 follows the fourth conductor 34 of the first conductor group 30 through coils 34b and 34a to reach segment C4, then follows the third conductor 33 of the first conductor group 30 through coils 33b and 33a to reach segment C3, and then flows out of the second brush 7b.

[0042] Even in the state shown in FIG. 3B , a force acts to rotate the rotor 10 and commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T8 and the segments C1 to C4 move in the first direction P. Thereafter, the magnetic pole portions T1 to T8 of the rotor core 2 and the segments C1 to C4 of the commutator 4 similarly move (rotate) in the first direction P, and the contact state (energized state) between the multiple brushes 7 and the segments C1 to C4 is sequentially switched, but the direction of rotation of the rotor 10 is always maintained in the first direction P. Therefore, the rotation of the motor 1 is maintained. Note that the direction of the current flowing through the motor 1 may all be reversed from that described above. In that case, the direction of rotation of the rotor 10 may be the second direction Q.

[0043] In this embodiment, half of the slots of the rotor 10 have two coils that are connected to the same combination of segments (two circumferentially adjacent segments), and such slots are arranged every other slot in the circumferential direction. Specifically, coils 31a and 31b pass through the first slot S1, and both are connected to circumferentially adjacent segments C1 and C2. Coils 32a and 32b pass through the fifth slot S5, and both are connected to segments C2 and C3. Coils 33a and 33b pass through the second slot S2, and both are connected to segments C3 and C4. Coils 34a and 34b pass through the sixth slot S6, and both are connected to segments C4 and C1. By configuring in this manner, when the first slot S1, the second slot S2, the fifth slot S5 and the sixth slot S6 face the first region 61 or the second region 62 on the q axis of the magnet 6, the coil pair passing through the slot becomes non-conductive.

[0044] In the motor 1 according to this embodiment, when the number of slots (= the number of magnetic pole portions) in the rotor 10 is N (N is an even number equal to or greater than eight), the number of segments in the commutator 4 is N / 2. This reduces the magnitude and frequency of switching noise generated during rotation. Furthermore, in the motor 1 according to this embodiment, when the first brush 7a is electrically connected to two circumferentially adjacent segments and the second brush 7b is electrically connected to the other two circumferentially adjacent segments (i.e., during switching), all of the coil pairs passing through slots facing the region on the q axis of the magnet 6 are de-energized. In other words, the motor 1 according to this embodiment allows energization switching when the magnetic poles are in the neutral position. Therefore, the motor 1 according to this embodiment reduces torque ripple due to current ripple and reduces noise caused by torque ripple.

[0045] Second Embodiment Next, a detailed description will be given of the wiring of the motor 1 according to a second embodiment of the present invention. The motor 1 according to this embodiment has the same configuration as the first embodiment, except for the wiring of the multiple conductors 3. The configuration of the motor 1 according to the first embodiment described with reference to Figures 2A and 2B can be applied to the motor 1 according to this embodiment as is.

[0046] 4A is a schematic diagram showing the wiring of the motor 1 according to this embodiment and the direction of current at the times shown in FIGS. 2A and 2B . As shown in FIG. 4A , the rotor 10 includes a plurality of conductors 3. In this embodiment, the plurality of conductors 3 is composed of a first conductor group 130 and a second conductor group 230. The first conductor group 130 includes a first conductor 131, a second conductor 132, a third conductor 133, and a fourth conductor 134. The second conductor group 230 includes a first conductor 231, a second conductor 232, a third conductor 233, and a fourth conductor 234. Both ends of each conductor are connected to segments of the commutator 4.

[0047] As shown in Fig. 4A , the first conductor 131 of the first conductor group 130 connected to the segment C1 via a riser (not shown) is wound across three adjacent magnetic pole portions (magnetic pole portions T1, T2, and T3) of the rotor core 2, i.e., across the first slot S1 and the seventh slot S7, to form a coil 131a, which is connected to the segment C2 via a riser (not shown). Note that in Fig. 4A , the coil 131a is illustrated as being wound less than once across the three adjacent magnetic pole portions (magnetic pole portions T1, T2, and T3) of the rotor core 2, but the number of windings of the coil 131a is arbitrary and may be less than one as in Fig. 4A , or may be one or more times (the same applies to all coils hereinafter).

[0048] The second conductor 132 of the first conductor group 130, which is connected to segment C2 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T3, T4, and T5) of the rotor core 2, i.e., across the fifth slot S5 and the fourth slot S4, to form a coil 132a, which is connected to segment C3 via a riser not shown.

[0049] The third conductor 133 of the first conductor group 130, which is connected to segment C3 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T5, T6, and T7) of the rotor core 2, i.e., across the second slot S2 and the eighth slot S8, to form a coil 133a, which is connected to segment C4 via a riser not shown.

[0050] The fourth wire 134 of the first wire group 130, which is connected to segment C4 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T7, T8, T1) of the rotor core 2, i.e., across the sixth slot S6 and the third slot S3, to form a coil 134a, which is connected to segment C1 via a riser not shown.

[0051] The first conductor 231 of the second conductor group 230, which is connected to segment C1 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T8, T7, and T6) of the rotor core 2, i.e., across the first slot S1 and the fourth slot S4, to form a coil 231a, which is connected to segment C2 via a riser not shown.

[0052] The second conductor 232 of the second conductor group 230, which is connected to segment C2 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T2, T1, and T8) of the rotor core 2, i.e., across the fifth slot S5 and the eighth slot S8, to form a coil 232a, which is connected to segment C3 via a riser not shown.

[0053] The third conductor 233 of the second conductor group 230, which is connected to segment C3 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T4, T3, T2) of the rotor core 2, i.e., across the second slot S2 and the third slot S3, to form a coil 233a, which is connected to segment C4 via a riser not shown.

[0054] The fourth wire 234 of the second wire group 230, which is connected to segment C4 via a riser not shown, is wound across three adjacent magnetic pole portions (magnetic pole portions T6, T5, T4) of the rotor core 2, i.e., across the sixth slot S6 and the seventh slot S7, to form a coil 234a, which is connected to segment C1 via a riser not shown.

[0055] As described above, the rotor 10 of the motor 1 has a plurality of coils, each of which is wound across two or more of the plurality of slots. In this embodiment, for convenience, the coils 131a and 231a are referred to as the first coil pair 131a, 231a, and the coils 133a and 233a are referred to as the second coil pair 133a, 233a. In this embodiment, the first coil pair 131a, 231a are parallel coils formed by the first conductor wire 131 of the first conductor wire group 130 and the first conductor wire 231 of the second conductor wire group 230, respectively, and the second coil pair 133a, 233a are parallel coils formed by the third conductor wire 133 of the first conductor wire group 130 and the third conductor wire 233 of the second conductor wire group 230, respectively. The first coil pair 131a, 231a is electrically connected to the first segment pair C1, C2 and passes through the first slot S1 (the slot between the magnetic pole portions T8 and T1). The second coil pair 133a, 233a is electrically connected to the second segment pair C3, C4 and passes through the second slot S2 (the slot between the magnetic pole portions T4 and T5).

[0056] 4A, the two segments C1 and C2 included in the first segment pair C1, C2 are both in contact with the first brush 7a and therefore have the same potential, while the two segments C3 and C4 included in the second segment pair C3, C4 are both in contact with the second brush 7b and therefore have the same potential. The first coil pair 131a, 231a is electrically connected to the first segment pair C1, C2, which are at the same potential, and therefore is not conducting electricity. The second coil pair 133a, 233a is electrically connected to the second segment pair C3, C4, which are at the same potential, and therefore is not conducting electricity. At this time, the first slot S1 through which the first coil pair 131a, 231a passes faces the first region 61 on the q axis of the magnet 6, and the second slot S2 through which the second coil pair 133a, 233a passes faces the second region 62 on the q axis of the magnet 6.

[0057] In this embodiment, two adjacent coils share two magnetic pole portions in the motor 1. For example, of the three magnetic pole portions (magnetic pole portions T1, T2, and T3) wound around the coil 131a, the magnetic pole portions T2 and T3 are included in the three magnetic pole portions (magnetic pole portions T2, T3, and T4) wound around the coil 233a adjacent to the coil 131a in the first direction P. Similarly, of the three magnetic pole portions (magnetic pole portions T2, T3, T4) wound around coil 233a, magnetic pole portions T3 and T4 are included in the three magnetic pole portions (magnetic pole portions T3, T4, T5) wound around coil 132a adjacent to coil 233a in the first direction P, of the three magnetic pole portions (magnetic pole portions T3, T4, T5) wound around coil 132a, magnetic pole portions T4 and T5 are included in the three magnetic pole portions (magnetic pole portions T4, T5, T6) wound around coil 234a adjacent to coil 132a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T4, T5, T6) wound around coil 234a, magnetic pole portions T5 and T6 are included in the three magnetic pole portions (magnetic pole portions T5, T6, T7) wound around coil 133a adjacent to coil 234a in the first direction P.

[0058] Furthermore, of the three magnetic pole portions (magnetic pole portions T5, T6, T7) wound around the coil 133a, the magnetic pole portions T6 and T7 are included in the three magnetic pole portions (magnetic pole portions T6, T7, T8) wound around the coil 231a adjacent to the coil 133a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T6, T7, T8) wound around the coil 231a, the magnetic pole portions T7 and T8 are included in the three magnetic pole portions (magnetic pole portions T7, T8, T1) wound around the coil 134a adjacent to the coil 231a in the first direction P. Of the three magnetic pole portions (magnetic pole portions T7, T8, T1) wound around coil 134a, magnetic pole portions T8 and T1 are included in the three magnetic pole portions (magnetic pole portions T8, T1, T2) wound around coil 232a adjacent to coil 134a in the first direction P, and of the three magnetic pole portions (magnetic pole portions T8, T1, T2) wound around coil 232a, magnetic pole portions T1 and T2 are included in the three magnetic pole portions (magnetic pole portions T1, T2, T3) wound around coil 131a adjacent to coil 232a in the first direction P.

[0059] In this embodiment, three adjacent coils share one magnetic pole portion in the motor 1. For example, the magnetic pole portion T1 is wound around three adjacent coils, namely, coil 134a, coil 232a, and coil 131a. Similarly, the magnetic pole portion T2 is wound around three adjacent coils, namely, coil 232a, coil 131a, and coil 233a. The magnetic pole portion T3 is wound around three adjacent coils, namely, coil 131a, coil 233a, and coil 132a. The magnetic pole portion T4 is wound around three adjacent coils, namely, coil 233a, coil 132a, and coil 234a. The magnetic pole portion T5 is wound around three adjacent coils, namely, coil 131a, coil 233a, and coil 132a. The magnetic pole portion T1 is wound around three adjacent coils, coil 232a, coil 234a, and coil 133a, the magnetic pole portion T2 is wound around three adjacent coils, coil 234a, coil 133a, and coil 231a, the magnetic pole portion T3 is wound around three adjacent coils, coil 133a, coil 231a, and coil 134a, and the magnetic pole portion T4 is wound around three adjacent coils, coil 231a, coil 134a, and coil 232a.

[0060] In this embodiment, two connection portions of the first conductor 131 of the first conductor group 130 are connected to two different circumferentially adjacent segments (segments C1 and C2) via a riser (not shown). Two connection portions of the second conductor 132 of the first conductor group 130 are connected to two different circumferentially adjacent segments (segments C2 and C3) via a riser (not shown). Two connection portions of the third conductor 133 of the first conductor group 130 are connected to two different circumferentially adjacent segments (segments C3 and C4) via a riser (not shown). Furthermore, two connection portions of the fourth conductor 134 of the first conductor group 130 are connected to two different circumferentially adjacent segments (segments C4 and C1) via a riser (not shown). Thus, in this embodiment, all of the conductors included in the first conductor group 130 are connected to two different circumferentially adjacent segments.

[0061] In this embodiment, two connection portions of the first conductor 231 of the second conductor group 230 are connected to two different circumferentially adjacent segments (segments C1 and C2) via a riser (not shown). Two connection portions of the second conductor 232 of the second conductor group 230 are connected to two different circumferentially adjacent segments (segments C2 and C3) via a riser (not shown). Two connection portions of the third conductor 233 of the second conductor group 230 are connected to two different circumferentially adjacent segments (segments C3 and C4) via a riser (not shown). Furthermore, two connection portions of the fourth conductor 234 of the second conductor group 230 are connected to two different circumferentially adjacent segments (segments C4 and C1) via a riser (not shown). Thus, in this embodiment, all of the conductors included in the second conductor group 230 are connected to two different circumferentially adjacent segments.

[0062] At the time shown in Figure 4A, a predetermined DC voltage is applied to the first brush 7a and the second brush 7b. A portion of the current flowing from the first brush 7a to segment C1 passes through coil 134a to reach segment C4 and then flows out from the second brush 7b. Another portion of the current flowing from the first brush 7a to segment C1 passes through coil 234a to reach segment C4 and then flows out from the second brush 7b. A portion of the current flowing from the first brush 7a to segment C2 passes through coil 132a to reach segment C3 and then flows out from the second brush 7b. Another portion of the current flowing from the first brush 7a to segment C2 passes through coil 232a to reach segment C3 and then flows out from the second brush 7b. As described above, the first coil pair 131a, 231a is electrically connected to the first segment pair C1, C2, which have the same potential, and therefore is not conducting electricity, and the second coil pair 133a, 233a is electrically connected to the second segment pair C3, C4, which have the same potential, and therefore is not conducting electricity.

[0063] In the state shown in Figure 4A, a force acts to rotate the rotor 10 and the commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T8 and the segments C1 to C4 move in the first direction P, transitioning to the state shown in Figure 4B.

[0064] 4B, the first brush 7a is in contact only with segment C1, and the second brush 7b is in contact only with segment C3. A portion of the current flowing from the first brush 7a to segment C1 passes through coil 131a or 231a to reach segment C2, then passes through coil 132a or 232a to reach segment C3, and then flows out of the second brush 7b. At the same time, another portion of the current flowing from the first brush 7a to segment C1 passes through coil 134a or 234a to reach segment C4, then passes through coil 133a or 233a to reach segment C3, and then flows out of the second brush 7b.

[0065] Even in the state shown in FIG. 4B , a force acts to rotate the rotor 10 and commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T8 and the segments C1 to C4 move in the first direction P. Thereafter, the magnetic pole portions T1 to T8 of the rotor core 2 and the segments C1 to C4 of the commutator 4 similarly move (rotate) in the first direction P, and the contact state (energized state) between the multiple brushes 7 and the segments C1 to C4 is sequentially switched, but the direction of rotation of the rotor 10 is always maintained in the first direction P. Therefore, the rotation of the motor 1 is maintained. Note that the direction of the current flowing through the motor 1 may all be reversed from that described above. In that case, the direction of rotation of the rotor 10 may be the second direction Q.

[0066] In this embodiment, half of the slots of the rotor 10 have two coils that are connected to the same combination of segments (two circumferentially adjacent segments), and such slots are arranged every other slot in the circumferential direction. Specifically, the first slot S1 has a coil 131a and a coil 231a that are connected to the circumferentially adjacent segments C1 and C2. The fifth slot S5 has a coil 132a and a coil 232a that are connected to the segments C2 and C3. The second slot S2 has a coil 133a and a coil 233a that are connected to the segments C3 and C4. The sixth slot S6 has a coil 134a and a coil 234a that are connected to the segments C4 and C1. By configuring in this manner, when the first slot S1, the second slot S2, the fifth slot S5 and the sixth slot S6 face the first region 61 or the second region 62 on the q axis of the magnet 6, the coil pair passing through the slot becomes non-conductive.

[0067] In the motor 1 according to this embodiment, when the number of slots (= the number of magnetic pole portions) in the rotor 10 is N (N is an even number equal to or greater than eight), the number of segments in the commutator 4 is N / 2. This reduces the magnitude and frequency of switching noise generated during rotation. Furthermore, in the motor 1 according to this embodiment, when the first brush 7a is electrically connected to two circumferentially adjacent segments and the second brush 7b is electrically connected to the other two circumferentially adjacent segments (i.e., during switching), all of the coil pairs passing through slots facing the region on the q axis of the magnet 6 are de-energized. In other words, the motor 1 according to this embodiment allows energization switching when the magnetic poles are in the neutral position. Therefore, the motor 1 according to this embodiment reduces torque ripple due to current ripple and reduces noise caused by torque ripple.

[0068] Third Embodiment Next, a detailed description will be given of the wiring of the motor 1 according to a third embodiment of the present invention. The motor 1 according to this embodiment has a similar configuration to the first embodiment, except that the rotor core 2 of the rotor 10 has 12 magnetic poles, the commutator 4 has 6 segments, and the wiring of the multiple conductors 3 is different. The configuration of the motor 1 according to the first embodiment described using Figures 2A and 2B can be partially applied to the motor 1 according to this embodiment.

[0069] Figure 5 is a schematic diagram showing the wiring configuration of the motor 1 in this embodiment and the direction of the current when the first brush 7a contacts segments C2 and C3 and the second brush 7b contacts segments C5 and C6.

[0070] 5, the rotor 10 has a plurality of magnetic pole portions (12 in this embodiment). Hereinafter, any one of the plurality of magnetic pole portions of the rotor 10 will be referred to as magnetic pole portion T1, and the magnetic pole portions will be referred to in order from magnetic pole portion T1 toward the first direction P as magnetic pole portions T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, and T12. Each of the plurality of conducting wires 3 is wound so as to span across the plurality of magnetic pole portions T1 to T12.

[0071] 5, the commutator 4 has a plurality of segments (six in this embodiment) arranged in the circumferential direction. Hereinafter, of the plurality of segments of the commutator 4, the segment that overlaps the magnetic pole portion T1 and the magnetic pole portion T2 in the circumferential direction will be referred to as segment C1, and the segments will be referred to in order from segment C1 toward the first direction P as segments C2, C3, C4, C5, and C6.

[0072] Segments C1 to C6 of the commutator 4 are in contact with multiple (two in this embodiment) brushes 7 (first brush 7a and second brush 7b) to allow current to flow. As shown in FIG. 5, the first brush 7a is in contact with the circumferentially adjacent segments C2 and C3 at the same time, and the second brush 7b is in contact with the circumferentially adjacent segments C5 and C6 at the same time. Hereinafter, segments C2 and C3 may be collectively referred to as the "first segment pair C2, C3," and segments C5 and C6 may be collectively referred to as the "second segment pair C5, C6."

[0073] The first brush 7a and the second brush 7b are arranged symmetrically with respect to the shaft 8. The first brush 7a and the second brush 7b are arranged on the d-axis, with the first brush 7a on the side where the north pole of the magnet 6 is arranged and the second brush 7b on the side where the south pole of the magnet 6 is arranged. The circumferential dimensions of each of the first brush 7a and the second brush 7b are such that they do not come into contact with three or more adjacent segments at the same time.

[0074] A plurality of slots are formed between two circumferentially adjacent magnetic pole portions of the plurality of magnetic pole portions T1 to T12 of the rotor 10. In this specification, for convenience, the slot between the magnetic pole portion T1 and the magnetic pole portion T2 is referred to as the first slot S1, the slot between the magnetic pole portion T7 and the magnetic pole portion T8 is referred to as the second slot S2, the slot between the magnetic pole portion T2 and the magnetic pole portion T3 is referred to as the third slot S3, the slot between the magnetic pole portion T8 and the magnetic pole portion T9 is referred to as the fourth slot S4, the slot between the magnetic pole portion T3 and the magnetic pole portion T4 is referred to as the fifth slot S5, the slot between the magnetic pole portion T9 and the magnetic pole portion T10 is referred to as the sixth slot S6, and the slot between the magnetic pole portion T10 and the magnetic pole portion T11 is referred to as the sixth slot S7. The slot between magnetic pole portion T4 and magnetic pole portion T5 is the seventh slot S7, the slot between magnetic pole portion T10 and magnetic pole portion T11 is the eighth slot S8, the slot between magnetic pole portion T5 and magnetic pole portion T6 is the ninth slot S9, the slot between magnetic pole portion T11 and magnetic pole portion T12 is the tenth slot S10, the slot between magnetic pole portion T6 and magnetic pole portion T7 is the eleventh slot S11, and the slot between magnetic pole portion T12 and magnetic pole portion T1 is the twelfth slot S12.

[0075] The magnet 6 has a first region 61 and a second region 62 on the q axis. The first region 61 and the second region 62 may be regions within a range of ±10° around the q axis of the magnet 6, or may be regions within a range of ±5° around the q axis of the magnet 6, for example. The first region 61 and the second region 62 are typically regions where two different magnetic poles (north and south poles) switch, but the strict boundary between the two different magnetic poles of the magnet 6 does not need to be specified.

[0076] As shown in Fig. 5 , the rotor 10 includes a plurality of conductors 3. In this embodiment, the plurality of conductors 3 are configured as a first conductor group 330. The first conductor group 330 includes a first conductor 331, a second conductor 332, a third conductor 333, a fourth conductor 334, a fifth conductor 335, and a sixth conductor 336. Both ends of each of the first conductor 331, the second conductor 332, the third conductor 333, the fourth conductor 334, the fifth conductor 335, and the sixth conductor 336 are connected to segments of the commutator 4.

[0077] As shown in Fig. 5, the first conducting wire 331 connected to the segment C1 via a riser (not shown) is wound across five adjacent magnetic pole portions (magnetic pole portions T11, T10, T9, T8, and T7) of the rotor core 2, i.e., across the tenth slot S10 and the eleventh slot S11, to form a coil 331a. Note that in Fig. 5, the coil 331a is illustrated as being wound less than once across the five adjacent magnetic pole portions (magnetic pole portions T11, T10, T9, T8, and T7) of the rotor core 2, but the number of windings of the coil 331a is arbitrary and may be less than one, as shown in Fig. 5, or one or more times (the same applies to all coils hereinafter).

[0078] The first conducting wire 331 forming the coil 331a extends to the vicinity of the magnetic pole portion T12 and is wound across five adjacent magnetic pole portions (magnetic pole portions T12, T1, T2, T3, and T4) of the rotor core 2, i.e., across the tenth slot S10 and the seventh slot S7, to form the coil 331b, which is connected to the segment C2 via a riser (not shown). That is, the first conducting wire 331 forms a plurality of coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T5 and T6) are located between the two coils 331a and 331b formed by the single first conducting wire 331.

[0079] The second conducting wire 332, connected to the segment C2 via a riser (not shown), is wound across five adjacent magnetic pole portions (magnetic pole portions T1, T12, T11, T10, and T9) of the rotor core 2, i.e., across the first slot S1 and the fourth slot S4, to form a coil 332a. The second conducting wire 332 forming the coil 332a extends to the vicinity of the magnetic pole portion T2 and is wound across five adjacent magnetic pole portions (magnetic pole portions T2, T3, T4, T5, and T6) of the rotor core 2, i.e., across the first slot S1 and the eleventh slot S11, to form a coil 332b, which is connected to the segment C3 via a riser (not shown). That is, the second conducting wire 332 forms a plurality of coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T7 and T8) are present between the two coils 332a and 332b formed by one second conducting wire 332.

[0080] The third conducting wire 333, connected to the segment C3 via a riser (not shown), is wound across five adjacent magnetic pole portions (magnetic pole portions T3, T2, T1, T12, and T11) of the rotor core 2, i.e., across the fifth slot S5 and the eighth slot S8, to form a coil 333a. The third conducting wire 333 forming the coil 333a extends to the vicinity of the magnetic pole portion T4, and is wound across five adjacent magnetic pole portions (magnetic pole portions T4, T5, T6, T7, and T8) of the rotor core 2, i.e., across the fifth slot S5 and the fourth slot S4, to form a coil 333b, which is connected to the segment C4 via a riser (not shown). That is, the third conducting wire 333 forms a plurality of coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T9 and T10) are present between the two coils 333a and 333b formed by one third conducting wire 333.

[0081] The fourth conducting wire 334, connected to segment C4 via a riser (not shown), is wound across five adjacent magnetic pole portions (magnetic pole portions T5, T4, T3, T2, and T1) of the rotor core 2, i.e., across the ninth slot S9 and the twelfth slot S12, to form coil 334a. The fourth conducting wire 334 forming coil 334a extends to the vicinity of magnetic pole portion T6 and is wound across five adjacent magnetic pole portions (magnetic pole portions T6, T7, T8, T9, and T10) of the rotor core 2, i.e., across the ninth slot S9 and the eighth slot S8, to form coil 334b, which is connected to segment C5 via a riser (not shown). That is, the fourth conducting wire 334 forms multiple coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T11 and T12) are present between the two coils 334a and 334b ​​formed by one fourth conducting wire 334.

[0082] The fifth conducting wire 335, connected to the segment C5 via a riser (not shown), is wound across five adjacent magnetic pole portions (magnetic pole portions T7, T6, T5, T4, and T3) of the rotor core 2, i.e., across the second slot S2 and the third slot S3, to form a coil 335a. The fifth conducting wire 335 forming the coil 335a extends to the vicinity of the magnetic pole portion T8 and is wound across five adjacent magnetic pole portions (magnetic pole portions T8, T9, T10, T11, and T12) of the rotor core 2, i.e., across the second slot S2 and the twelfth slot S12, to form a coil 335b, which is connected to the segment C6 via a riser (not shown). That is, the fifth conducting wire 335 forms a plurality of coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T1 and T2) are present between the two coils 335a and 335b formed by the single fifth conducting wire 335.

[0083] The sixth conducting wire 336, connected to the segment C6 via a riser (not shown), is wound across five adjacent magnetic pole portions (magnetic pole portions T9, T8, T7, T6, and T5) of the rotor core 2, i.e., across the sixth slot S6 and the seventh slot S7, to form a coil 336a. The sixth conducting wire 336 forming the coil 336a extends to the vicinity of the magnetic pole portion T10 and is wound across five adjacent magnetic pole portions (magnetic pole portions T10, T11, T12, T1, and T2) of the rotor core 2, i.e., across the sixth slot S6 and the third slot S3, to form a coil 336b, which is connected to the segment C1 via a riser (not shown). That is, the sixth conducting wire 336 forms a plurality of coils (two in this embodiment) wound across five circumferentially adjacent (consecutive) magnetic pole portions. In the circumferential direction, two magnetic pole portions (magnetic pole portions T3 and T4) are present between the two coils 336a and 336b formed by the single sixth conducting wire 336.

[0084] As described above, the rotor 10 of the motor 1 has multiple coils, each of which is wound across two or more of the multiple slots. In this embodiment, for convenience, the coils 332a and 332b are referred to as the first coil pair 332a, 332b, and the coils 335a and 335b are referred to as the second coil pair 335a, 335b. In this embodiment, the first coil pair 332a, 332b is a series coil formed by a single first conducting wire 332, and the second coil pair 335a, 335b is a series coil formed by a single fifth conducting wire 335. The first coil pair 332a, 332b is electrically connected to the first segment pair C2, C3 and passes through the first slot S1 (the slot between the magnetic pole portions T1 and T2). The second coil pair 335a, 335b is electrically connected to the second segment pair C5, C6 and passes through the second slot S2 (the slot between the magnetic pole portions T7 and T8).

[0085] 5, the two segments C2 and C3 included in the first segment pair C2, C3 are both in contact with the first brush 7a and therefore have the same potential, while the two segments C5 and C6 included in the second segment pair C5, C6 are both in contact with the second brush 7b and therefore have the same potential. The first coil pair 332a, 332b is electrically connected to the first segment pair C2, C3, which has the same potential, and therefore is not conducting electricity. The second coil pair 335a, 335b is electrically connected to the second segment pair C5, C6, which has the same potential, and therefore is not conducting electricity. At this time, the first slot S1 through which the first coil pair 332a, 332b passes faces the first region 61 on the q axis of the magnet 6, and the second slot S2 through which the second coil pair 335a, 335b passes faces the second region 62 on the q axis of the magnet 6.

[0086] In this embodiment, motor 1 has two adjacent coils sharing four magnetic pole portions, three adjacent coils sharing three magnetic pole portions, four adjacent coils sharing two magnetic pole portions, and five adjacent coils sharing one magnetic pole portion.

[0087] In this embodiment, two connection portions of the first conducting wire 331 are connected to two different circumferentially adjacent segments (segments C1 and C2) via risers (not shown). Two connection portions of the second conducting wire 332 are connected to two different circumferentially adjacent segments (segments C2 and C3) via risers (not shown). Two connection portions of the third conducting wire 333 are connected to two different circumferentially adjacent segments (segments C3 and C4) via risers (not shown). Two connection portions of the fourth conducting wire 334 are connected to two different circumferentially adjacent segments (segments C4 and C5) via risers (not shown). Two connection portions of the fifth conducting wire 335 are connected to two different circumferentially adjacent segments (segments C5 and C6) via risers (not shown). Two connection portions of the sixth conducting wire 336 are connected to two different circumferentially adjacent segments (segments C6 and C1) via risers (not shown). In this manner, in this embodiment, all of the conductors included in the first conductor group 330 are each connected to two different segments that are adjacent to each other in the circumferential direction.

[0088] 5, a predetermined DC voltage is applied to the first brush 7a and the second brush 7b. Current flowing from the first brush 7a to segment C2 follows the first conductor 331 of the first conductor group 330 through coils 331b and 331a to reach segment C1, then through coils 336b and 336a to reach segment C6, and then flows out of the second brush 7b. At the same time, current flowing from the first brush 7a to segment C3 follows the third conductor 333 of the first conductor group 330 through coils 333a and 333b to reach segment C4, then through the fourth conductor 334 of the first conductor group 330 through coils 334a and 334b ​​to reach segment C5, and then flows out of the second brush 7b. As described above, the first coil pair 332a, 332b is electrically connected to the first segment pair C2, C3, which has the same potential, and therefore is not conducting electricity, and the second coil pair 335a, 335b is electrically connected to the second segment pair C5, C6, which has the same potential, and therefore is not conducting electricity.

[0089] In the state shown in FIG. 5 , a force acts to rotate the rotor 10 and commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T12 and the segments C1 to C6 move in the first direction P. Thereafter, the magnetic pole portions T1 to T12 of the rotor core 2 and the segments C1 to C6 of the commutator 4 move (rotate) in the first direction P, and the contact state (energized state) between the multiple brushes 7 and the segments C1 to C6 is sequentially switched, but the direction of rotation of the rotor 10 is always maintained in the first direction P. Therefore, the rotation of the motor 1 is maintained. Note that the direction of the current flowing through the motor 1 may all be reversed from that described above. In that case, the direction of rotation of the rotor 10 may be the second direction Q.

[0090] In this embodiment, half of the slots of the rotor 10 have two coils connected to the same combination of segments (two circumferentially adjacent segments), and such slots are arranged alternately in the circumferential direction. Specifically, coils 332a and 332b pass through the first slot S1, both of which are connected to circumferentially adjacent segments C2 and C3. Coils 333a and 333b pass through the fifth slot S5, both of which are connected to segments C3 and C4. Coils 334a and 334b ​​pass through the ninth slot S9, both of which are connected to segments C4 and C5. Coils 335a and 335b pass through the second slot S2, both of which are connected to segments C5 and C6. Coils 336a and 336b pass through the sixth slot S6, both of which are connected to segments C6 and C1. Coils 331a and 331b pass through tenth slot S10, and are both connected to segments C1 and C2. With this configuration, when the first slot S1, second slot S2, fifth slot S5, sixth slot S6, ninth slot S9, and tenth slot S10 face the first region 61 or the second region 62 on the q axis of the magnet 6, the coil pair passing through the slot becomes non-conductive.

[0091] In the motor 1 according to this embodiment, when the number of slots (= the number of magnetic pole portions) in the rotor 10 is N (N is an even number equal to or greater than eight), the number of segments in the commutator 4 is N / 2. This reduces the magnitude and frequency of switching noise generated during rotation. Furthermore, in the motor 1 according to this embodiment, when the first brush 7a is electrically connected to two circumferentially adjacent segments and the second brush 7b is electrically connected to the other two circumferentially adjacent segments (i.e., during switching), all of the coil pairs passing through slots facing the region on the q axis of the magnet 6 are de-energized. In other words, the motor 1 according to this embodiment allows energization switching when the magnetic poles are in the neutral position. Therefore, the motor 1 according to this embodiment reduces torque ripple due to current ripple and reduces noise caused by torque ripple.

[0092] Fourth Embodiment Next, a detailed description will be given of the wiring of the motor 1 according to a fourth embodiment of the present invention. The motor 1 according to this embodiment has the same configuration as the motor 1 according to the third embodiment, except for the wiring of the plurality of conductors 3.

[0093] FIG. 6 is a schematic diagram showing the wiring of the motor 1 according to this embodiment and the direction of current when the first brush 7a contacts segments C2 and C3 and the second brush 7b contacts segments C5 and C6. As shown in FIG. 6 , the rotor 10 includes a plurality of conductors 3. In this embodiment, the plurality of conductors 3 are composed of a first conductor group 430 and a second conductor group 530. The first conductor group 430 includes a first conductor 431, a second conductor 432, a third conductor 433, a fourth conductor 434, a fifth conductor 435, and a sixth conductor 436. The second conductor group 530 includes a first conductor 531, a second conductor 532, a third conductor 533, a fourth conductor 534, a fifth conductor 535, and a sixth conductor 536. Both ends of each conductor are connected to the segments of the commutator 4.

[0094] As shown in Fig. 6 , the first conductor 431 of the first conductor group 430 connected to the segment C1 via a riser (not shown) is wound across five adjacent magnetic pole portions (magnetic pole portions T11, T10, T9, T8, and T7) of the rotor core 2, i.e., across the tenth slot S10 and the eleventh slot S11, to form a coil 431a, which is connected to the segment C2 via a riser (not shown). Note that in Fig. 6 , the coil 431a is illustrated as being wound less than once across the five adjacent magnetic pole portions (magnetic pole portions T11, T10, T9, T8, and T7) of the rotor core 2, but the number of windings of the coil 431a is arbitrary and may be less than one as shown in Fig. 6 , or one or more times (the same applies to all coils hereinafter).

[0095] The second conductor 432 of the first conductor group 430, which is connected to segment C2 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T1, T12, T11, T10, and T9) of the rotor core 2, i.e., across the first slot S1 and the fourth slot S4, to form a coil 432a, which is connected to segment C3 via a riser not shown.

[0096] The third wire 433 of the first wire group 430, which is connected to segment C3 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T3, T2, T1, T12, and T11) of the rotor core 2, i.e., across the fifth slot S5 and the eighth slot S8, to form a coil 433a, which is connected to segment C4 via a riser not shown.

[0097] The fourth wire 434 of the first wire group 430, which is connected to segment C4 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T5, T4, T3, T2, and T1) of the rotor core 2, i.e., across the ninth slot S9 and the twelfth slot S12, to form a coil 434a, which is connected to segment C5 via a riser not shown.

[0098] The fifth conductor 435 of the first conductor group 430, which is connected to segment C5 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T7, T6, T5, T4, and T3) of the rotor core 2, i.e., across the second slot S2 and the third slot S3, to form a coil 435a, which is connected to segment C6 via a riser not shown.

[0099] The sixth conductor 436 of the first conductor group 430, which is connected to segment C6 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T9, T8, T7, T6, and T5) of the rotor core 2, i.e., across the sixth slot S6 and the seventh slot S7, to form a coil 436a, which is connected to segment C1 via a riser not shown.

[0100] The first conductor 531 of the second conductor group 530, which is connected to segment C1 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T12, T1, T2, T3, and T4) of the rotor core 2, i.e., across the tenth slot S10 and the seventh slot S7, to form a coil 531a, which is connected to segment C2 via a riser not shown.

[0101] The second conductor 532 of the second conductor group 530, which is connected to segment C2 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T2, T3, T4, T5, and T6) of the rotor core 2, i.e., across the first slot S1 and the eleventh slot S11, to form a coil 532a, which is connected to segment C3 via a riser not shown.

[0102] The third conductor 533 of the second conductor group 530, which is connected to segment C3 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T4, T5, T6, T7, and T8) of the rotor core 2, i.e., across the fifth slot S5 and the fourth slot S4, to form a coil 533a, which is connected to segment C4 via a riser not shown.

[0103] The fourth wire 534 of the second wire group 530, which is connected to segment C4 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T6, T7, T8, T9, and T10) of the rotor core 2, i.e., across the ninth slot S9 and the eighth slot S8, forming a coil 534a, which is connected to segment C5 via a riser not shown.

[0104] The fifth conductor 535 of the second conductor group 530, which is connected to segment C5 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T8, T9, T10, T11, and T12) of the rotor core 2, i.e., across the second slot S2 and the twelfth slot S12, to form a coil 535a, which is connected to segment C6 via a riser not shown.

[0105] The sixth conductor 536 of the second conductor group 530, which is connected to segment C6 via a riser not shown, is wound across five adjacent magnetic pole portions (magnetic pole portions T10, T11, T12, T1, and T2) of the rotor core 2, i.e., across the sixth slot S6 and the third slot S3, to form a coil 536a, which is connected to segment C1 via a riser not shown.

[0106] As described above, the rotor 10 of the motor 1 has a plurality of coils, each of which is wound across two or more of the plurality of slots. In this embodiment, for convenience, the coils 432a and 532a are referred to as the first coil pair 432a and 532a, and the coils 435a and 535a are referred to as the second coil pair 435a and 535a. In this embodiment, the first coil pair 432a and 532a are parallel coils formed by the second conductor wire 432 of the first conductor wire group 430 and the second conductor wire 532 of the second conductor wire group 530, respectively, and the second coil pair 435a and 535a are parallel coils formed by the fifth conductor wire 435 of the first conductor wire group 430 and the fifth conductor wire 535 of the second conductor wire group 530, respectively. The first coil pair 432a, 532a is electrically connected to the first segment pair C2, C3 and passes through the first slot S1 (the slot between the magnetic pole portions T12 and T1). The second coil pair 435a, 535a is electrically connected to the second segment pair C5, C6 and passes through the second slot S2 (the slot between the magnetic pole portions T7 and T8).

[0107] 6, the two segments C2 and C3 included in the first segment pair C2, C3 are both in contact with the first brush 7a and therefore have the same potential, while the two segments C5 and C6 included in the second segment pair C5, C6 are both in contact with the second brush 7b and therefore have the same potential. The first coil pair 432a, 532a is electrically connected to the first segment pair C2, C3, which are at the same potential, and therefore is not conducting electricity. The second coil pair 435a, 535a is electrically connected to the second segment pair C5, C6, which are at the same potential, and therefore is not conducting electricity. At this time, the first slot S1 through which the first coil pair 432a, 532a passes faces the first region 61 on the q axis of the magnet 6, and the second slot S2 through which the second coil pair 435a, 535a passes faces the second region 62 on the q axis of the magnet 6.

[0108] In this embodiment, motor 1 has two adjacent coils sharing four magnetic pole portions, three adjacent coils sharing three magnetic pole portions, four adjacent coils sharing two magnetic pole portions, and five adjacent coils sharing one magnetic pole portion.

[0109] In this embodiment, two connection portions of the first conductor 431 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C1 and C2) via a riser (not shown). Two connection portions of the second conductor 432 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C2 and C3) via a riser (not shown). Two connection portions of the third conductor 433 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C3 and C4) via a riser (not shown). Two connection portions of the fourth conductor 434 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C4 and C5) via a riser (not shown). Two connection portions of the fifth conductor 435 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C5 and C6) via a riser (not shown). Two connection portions of the sixth conductor 436 of the first conductor group 430 are connected to two different circumferentially adjacent segments (segments C6 and C1) via risers (not shown). Thus, in this embodiment, all of the conductors included in the first conductor group 430 are connected to two different circumferentially adjacent segments.

[0110] In this embodiment, two connection portions of the first conductor 531 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C1 and C2) via a riser (not shown). Two connection portions of the second conductor 532 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C2 and C3) via a riser (not shown). Two connection portions of the third conductor 533 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C3 and C4) via a riser (not shown). Two connection portions of the fourth conductor 534 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C4 and C5) via a riser (not shown). Two connection portions of the fifth conductor 535 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C5 and C6) via a riser (not shown). Two connection portions of the sixth conductor 536 of the second conductor group 530 are connected to two different circumferentially adjacent segments (segments C6 and C1) via risers (not shown). Thus, in this embodiment, all of the conductors included in the second conductor group 530 are connected to two different circumferentially adjacent segments.

[0111] At the time shown in Figure 6, a predetermined DC voltage is applied to the first brush 7a and the second brush 7b. Current flowing from the first brush 7a to segment C2 passes through coil 431a or 531a to reach segment C1, then passes through coil 436a or 536a to reach segment C6, and then flows out of the second brush 7b. Current flowing from the first brush 7a to segment C3 passes through coil 433a or 533a to reach segment C4, then passes through coil 434a or 534a to reach segment C5, and then flows out of the second brush 7b. As described above, the first coil pair 432a, 532a is electrically connected to the first segment pair C2, C3, which are at the same potential, and therefore is not conducting. The second coil pair 435a, 535a is electrically connected to the second segment pair C5, C6, which are at the same potential, and therefore is not conducting.

[0112] In the state shown in FIG. 6 , a force acts to rotate the rotor 10 and commutator 4 in the first direction P. Therefore, the magnetic pole portions T1 to T12 and the segments C1 to C6 move in the first direction P. Thereafter, the magnetic pole portions T1 to T12 of the rotor core 2 and the segments C1 to C6 of the commutator 4 move (rotate) in the first direction P, and the contact state (energized state) between the multiple brushes 7 and the segments C1 to C6 is sequentially switched, but the direction of rotation of the rotor 10 is always maintained in the first direction P. Therefore, the rotation of the motor 1 is maintained. Note that the direction of the current flowing through the motor 1 may all be reversed from that described above. In that case, the direction of rotation of the rotor 10 may be the second direction Q.

[0113] In this embodiment, half of the slots of the rotor 10 have two coils that are connected to the same combination of segments (two circumferentially adjacent segments), and such slots are arranged alternately in the circumferential direction. Specifically, coils 432a and 532a pass through the first slot S1, and both are connected to circumferentially adjacent segments C2 and C3. Coils 433a and 533a pass through the fifth slot S5, and both are connected to segments C3 and C4. Coils 434a and 534a pass through the ninth slot S9, and both are connected to segments C4 and C5. Coils 435a and 535a pass through the second slot S2, and both are connected to segments C5 and C6. Coils 436a and 536a pass through the sixth slot S6, and both are connected to segments C6 and C1. Coils 431a and 531a pass through tenth slot S10, and are both connected to segments C1 and C2. With this configuration, when the first slot S1, second slot S2, fifth slot S5, sixth slot S6, ninth slot S9, and tenth slot S10 face the first region 61 or the second region 62 on the q axis of magnet 6, the coil pairs passing through the slots are de-energized.

[0114] In the motor 1 according to this embodiment, when the number of slots (= the number of magnetic pole portions) in the rotor 10 is N (N is an even number equal to or greater than eight), the number of segments in the commutator 4 is N / 2. This reduces the magnitude and frequency of switching noise generated during rotation. Furthermore, in the motor 1 according to this embodiment, when the first brush 7a is electrically connected to two circumferentially adjacent segments and the second brush 7b is electrically connected to the other two circumferentially adjacent segments (i.e., during switching), all of the coil pairs passing through slots facing the region on the q axis of the magnet 6 are de-energized. In other words, the motor 1 according to this embodiment allows energization switching when the magnetic poles are in the neutral position. Therefore, the motor 1 according to this embodiment reduces torque ripple due to current ripple and reduces noise caused by torque ripple.

[0115] Although the motor of the present invention has been described above with reference to preferred embodiments, the motor of the present invention is not limited to the configuration of the above embodiments. For example, the number of magnetic poles of the magnet, the number of magnetic pole portions of the rotor core, and the number of commutator segments in the above embodiments are merely examples and can be selected as appropriate, provided that they comply with the conditions of the present invention.

[0116] In the above embodiment, the magnet 6 is cylindrical and has two different magnetic poles (N and S poles) alternately magnetized in the circumferential direction, but the present invention is not limited to using such a magnet. For example, in the magnet 6 shown in Fig. 1, multiple magnetic members separated by solid lines indicating the boundary between the S and N poles may be attached to the inner surface of the housing 5 so that the S and N poles are alternately arranged in the circumferential direction.

[0117] The multiple conductors may be connected in series and wound around multiple magnetic poles to form multiple coils, or may be connected in parallel and wound around multiple magnetic poles to form multiple coils. The currents passing through the multiple conductors may be in phase.

[0118] Furthermore, those skilled in the art can appropriately modify the motor of the present invention and change the shape, dimensions, and combination of various components in accordance with conventional knowledge. As long as such modifications still include the components of the present invention, they are of course included in the scope of the present invention.

[0119] 1...motor, 4...commutator, 6...magnet, 61...first region, 62...second region, 7...brush, 7a...first brush, 7b...second brush, 10...rotor, 31a, 31b...first coil pair, 33a, 33b...second coil pair, S1...first slot, S2...second slot, C1, C2...first segment pair, C3, C4...second segment pair.

Claims

1. A motor comprising: a rotor having a plurality of slots including a first slot and a second slot, and a plurality of coils including a first coil pair and a second coil pair; a commutator having a plurality of segments including a first segment pair and a second segment pair; a plurality of brushes in contact with the commutator; and a magnet having a first region and a second region on the q-axis, wherein the first coil pair electrically connected to the first segment pair passes through the first slot, and the second coil pair electrically connected to the second segment pair passes through the second slot, and when the two segments included in the first segment pair are at the same potential and the two segments included in the second segment pair are at the same potential, the first slot faces the first region and the second slot faces the second region.

2. The motor described in claim 1, wherein the plurality of brushes include a first brush and a second brush, the two segments included in the first segment pair are adjacent to each other in the circumferential direction, and the two segments included in the second segment pair are adjacent to each other in the circumferential direction, and when the two segments included in the first segment pair are at the same potential and the two segments included in the second segment pair are at the same potential, the two segments included in the first segment pair contact the first brush and the two segments included in the second segment pair contact the second brush.

3. A motor comprising: a shaft; a rotor fixed to the shaft; a commutator fixed to the shaft; a plurality of brushes in contact with the commutator; and a magnet having a first region and a second region on a q-axis, wherein the rotor has a plurality of slots including a first slot and a second slot, and a plurality of coils including a first coil pair and a second coil pair, the commutator has a plurality of segments including a first segment pair and a second segment pair, the first coil pair electrically connected to the first segment pair passes through the first slot, and the second coil pair electrically connected to the second segment pair passes through the second slot, and among the plurality of brushes, a first brush connects to two segments included in the first segment pair and a second brush connects to two segments included in the second segment pair, and the first slot faces the first region and the second slot faces the second region.

4. The motor according to any one of claims 1 to 3, wherein each of the plurality of coils is wound across two or more of the plurality of slots.

5. A motor according to any one of claims 1 to 4, wherein the rotor has N slots (where N is an even number equal to or greater than 8), and the commutator has N / 2 segments.

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