brushed motor

Abstract

The present application relates to a brush motor which realizes miniaturization and high torque with a simple structure. The brush motor (1) of the present application is provided with a rotor core (10) provided to a rotor (6), s teeth (11) provided to the rotor core (10), s concentrated-winding coils (7) in which electric wires are wound around the teeth (11) respectively, a commutator (8) provided to the rotor (6) in a manner that cannot rotate relatively, c commutator segments (9) provided to the commutator (8) and connected to the coils (7), p pairs of magnet poles (5) provided to a stator (3) and arranged in opposition to the teeth (11), and brushes (21) which are in sliding contact with the commutator segments (9) to supply electric current to the coils (7), 0.5 < p / s < 1, and s < c. Note that the vane angle (θ W ) of the teeth (11) is preferably set to an angle at which a magnetization region of one magnet pole (5) covers a magnet angle (θ M ) of the rotation axis (C) or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a brush motor in which current is supplied from a brush to a coil via a commutator. BACKGROUND

[0002] In the past, a brush DC motor in which the number of coils is larger than the number of field magnetic poles has been known. As an example of such a motor, a four-pole six-slot motor having a concentrated winding structure (a structure in which a coil wire is separately wound on each tooth) with four field magnetic poles and six core slots (slots) can be given. In this motor, the same number of coils as the number of core slots is provided, and six coils, which are more than the number of field magnetic poles, i.e., four, are built in (see Patent Document 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. H11-69747

[0006] In a motor having a coil with a concentrated winding structure, in a case where the number of coils is made larger than the number of field magnetic poles, the vane angle in a cross section perpendicular to the rotation axis of the motor is narrower than the magnet angle. Due to this, there is a problem in that the pickup of the magnet magnetic flux becomes insufficient, and thus the magnetic flux cannot be effectively utilized. In addition, in a case where a coil with a distributed winding structure in which a coil wire is wound in a manner of spanning over a plurality of teeth is adopted, the coil end portion expands and the winding resistance becomes large, and thus there is a problem in that it is difficult to achieve high torque. SUMMARY

[0007] One of the objects of the present application is to provide a brush motor which is made in consideration of the above-described problems, and which can achieve miniaturization and high torque with a simple structure. Note that the object is not limited to the above, and an effect brought about by each structure shown in the "DETAILED DESCRIPTION" described later, and an effect which cannot be obtained by the conventional technology can also be included as another object of the present application.

[0008] The brush motor of the present application includes a rotor core provided to a rotor, s teeth provided to the rotor core, s coils of concentrated winding in which a coil wire is wound on each tooth, a commutator provided to the rotor in a manner that cannot rotate relative to the rotor, c commutator segments provided to the commutator and connected to the coils, p pairs of field magnetic poles provided to a stator and arranged opposite to the teeth, and a brush in sliding contact with the commutator segments to supply current to the coils, and the following Inequality A and Inequality B are satisfied,

[0009] 0.5 < p / s < 1... (Inequality A)

[0010] s < c…(Inequality B).

[0011] Invention Effects

[0012] According to the publicly available technology, it is possible to fully collect magnetic flux from the magnet and to achieve miniaturization and high torque with a simple structure. Attached Figure Description

[0013] Figure 1 This is an exploded perspective view of the brushed motor as a first embodiment.

[0014] Figure 2 It is built into Figure 1 A 3D view of the rotor of a brushed motor.

[0015] Figure 3 yes Figure 1 A cross-sectional view of a brushed motor.

[0016] Figure 4 It is shown Figure 1 A diagram showing the magnet angle and blade angle of a brushed motor.

[0017] Figure 5 It is shown Figure 1 The circuit diagram of the power supply circuit in a brushed motor.

[0018] Figure 6 (A) is a diagram showing a brushed motor (four poles, six slots) as a comparative example. Figure 6 (B) is shown Figure 1 A diagram of a brushed motor (four poles, three slots).

[0019] Figure 7 (A) is a diagram showing a brushed motor (without auxiliary poles) as a comparative example. Figure 7 (B) is shown Figure 1 A diagram of a brushed motor (with auxiliary poles).

[0020] Figure 8 This is a cross-sectional view of a brushed motor as a second embodiment.

[0021] Figure 9 It is shown Figure 8 A diagram showing the magnet angle and blade angle of a brushed motor.

[0022] Figure 10 It is shown Figure 8 The circuit diagram of the power supply circuit in a brushed motor.

[0023] Figure 11 This is a cross-sectional view of a brushed motor as a third embodiment.

[0024] Figure 12 It is shownFigure 11 A diagram showing the magnet angle and blade angle of a brushed motor.

[0025] Figure 13 It is shown Figure 11 The circuit diagram of the power supply circuit in a brushed motor.

[0026] Figure 14 It is a graph used to illustrate the magnet angle of a toroidal magnet.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1, 41, 51... brushed motors;

[0029] 2...outer shell;

[0030] 3...Stator;

[0031] 4... Magnet;

[0032] 5...Magnetic poles of the magnet;

[0033] 6...rotor;

[0034] 7...coil;

[0035] 8...commutator;

[0036] 9...commutator segments;

[0037] 10... Iron core (rotor core);

[0038] 11...teeth;

[0039] 12...column;

[0040] 13...blade section;

[0041] 14...auxiliary electrode;

[0042] 15... Auxiliary pole section;

[0043] 16... Auxiliary electrode blade section;

[0044] 17...slit;

[0045] 20... axis;

[0046] 21... Brushes;

[0047] 22...brush arm;

[0048] 23, 42, 52... power supply circuits;

[0049] θ W ...blade angle;

[0050] θ M ...magnet angle

[0051] C... rotation axis

[0052] W... slit width DETAILED DESCRIPTION

[0053] [1. First Embodiment]

[0054] [A. Structure]

[0055] Figure 1 is an exploded perspective view showing main components of a brush motor 1 (brushed motor) as a first embodiment. The brush motor 1 is provided with a stator 3, a rotor 6, and a shaft 20. As shown in Figure 1 , the stator 3 and the rotor 6 are housed inside a housing 2 formed in a bottomed cylindrical shape. In Figure 1 , a cover member (end shield) that closes an open end portion (left end portion in Figure 1 ) of the housing 2 is omitted. In addition, the shaft 20 is a shaft-like member that is supported to the housing 2 and the end shield via a bearing not shown. The stator 3 is fixed to the housing 2, and the rotor 6 is fixed to the shaft 20 to rotate integrally with the shaft 20. A central axis of the shaft 20 coincides with a rotation axis C of the rotor 6.

[0056] A magnet 4 (permanent magnet) for forming a magnetic field acting on the rotor 6 is provided to the stator 3. The magnet 4 has p pairs of magnet poles 5 formed in a curved surface shape. The shape of the magnet pole 5 is, for example, a circular arc surface shape or a similar shape. The magnet poles 5 are installed along an inner peripheral surface of the housing 2, and are arranged at a predetermined interval in a circumferential direction (circumferential direction of a circle with the rotation axis C as the center in a cross section perpendicular to the rotation axis C) from each other. The direction of the magnetic field is set to a direction from the outside toward the inside of the housing 2 or a reverse direction thereof (a direction from the inside toward the outside). In the present application, the direction of the magnetic field is reversed between adjacent magnet poles 5.

[0057] Figure 1 The magnet 4 shown in Figure 1 is formed by combining four magnet pieces each of which is magnetized with one set of pairs of poles in one piece, but can be formed by combining magnet pieces each of which is magnetized with a plurality of sets of pairs of poles in one piece. Alternatively, as the above-described magnet 4, a cylindrical magnet (annular magnet) that is not divided into a plurality of magnet pieces can be used. In the annular magnet, a plurality of magnet poles 5 (magnetized regions) are arranged adjacent to each other in the circumferential direction, but a non-magnetized region can be provided between these magnet poles 5. The non-magnetized region refers to a region that substantially does not contribute to the formation of the magnetic field for the rotor 6, and corresponds to a position of a gap between the magnet poles 5 shown in Figure 1 . In this way, it is not necessary to make the number of physical divisions of the magnet 4 coincide with the number of magnetic divisions.

[0058] The rotor 6 is provided with a core 10 (rotor core) fixed so as not to relatively rotate with respect to the shaft 20 and a commutator 8 (commutator). The core 10 is formed by laminating a plurality of steel sheets of the same shape. The lamination direction of the steel sheets is the same as the extending direction of the rotation axis C. The core 10 is provided with s teeth 11 in a shape projecting radially from the rotation axis C in a cross section perpendicular to the rotation axis C. By winding a wire on each tooth 11, s coils 7 (concentrated winding coils) are formed.

[0059] The commutator 8 is a member for energizing the coils 7 in an appropriate direction to an appropriate position corresponding to the rotation angle of the rotor 6. The commutator 8 is provided with c commutator segments 9 formed in a curved surface shape. The shape of the commutator segments 9 is formed, for example, in a circular arc surface shape or a similar shape. These commutator segments 9 are arranged in a manner adjacent in the circumferential direction along the outer circumferential surface of the shaft 20. Each commutator segment 9 is connected with each coil 7 through a power supply circuit 23. The circuit structure of the power supply circuit 23 will be described later.

[0060] Around the commutator 8, a brush 21 (brush) is provided in a manner contacting the surface of the commutator segment 9. The brush 21 is mounted to one end of a brush arm 22, and is supported in a state of being elastically pressed against the commutator segment 9. In addition, the brush 21 and the brush arm 22 are provided in pairs. The other end of each brush arm 22 is extended to the outside of the housing 2, for example, through a cover member, and becomes a terminal for power supply. Each brush 21 is provided in a manner contacting any one of the c commutator segments 9.

[0061] With respect to the relationship of the p pairs of magnetic poles 5, the s coils 7, and the c commutator segments 9, in the present application, the values of p, s, and c are set in a manner that the following inequalities are all satisfied. That is, the value obtained by dividing the number of groups (two is one group) of the magnetic poles 5 (p) by the number of the coils 7 (s) is set to be greater than 0.5 and less than 1. In addition, the number of the coils 7 (s) is set to be smaller than the number of the commutator segments 9 (c).

[0062] 0.5 < p / s < 1 (Inequality A)

[0063] s < c (Inequality B)

[0064] Note that, if Inequality A is transformed, it becomes "p < s < 2p". Therefore, the number of the coils 7 (s) is set to be greater than the number of groups of the magnetic poles 5 (p) and smaller than the total number of the magnetic poles 5 (2p).

[0065] Figure 2is a perspective view showing the rotor 6 including the iron core 10 from which the electric wires of the coil 7 are removed. Each tooth 11 has a column portion 12 and a vane portion 13. The column portion 12 is a portion extending toward the radial outer side of the rotor 6. Further, the vane portion 13 is a portion of a curved surface shape (a circular arc surface shape or a similar shape) spreading from the outer end portion of the column portion 12 in the circumferential direction of the rotor 6, and is disposed in a manner to oppose the magnet pole 5 in a non-contact manner. The electric wires of the coil 7 are wound around the column portion 12 in a concentrated winding manner in multiple layers.

[0066] Figure 3 is a cross-sectional view of the stator 3 and the rotor 6. Here, the cross-sectional view of the commutator segment 9 is also shown in superposition for convenience. In the brush motor 1, two pairs of magnet poles 5, three coils 7, and six commutator segments 9 are provided.(p, s, c) combinations are (2, 3, 6), and it is a four-pole three-slot motor.

[0067] The iron core 10 of the brush motor 1 of the first embodiment is provided with a sub pole 14. The sub pole 14 is a portion extending radially from the rotation axis C of the rotor 6 to strengthen the flow of magnetic flux, and is provided integrally with the iron core 10. As shown in Figure 3 , the sub pole 14 is provided in a manner to be disposed between the adjacent teeth 11 and to divide the coils 7 in a cross section perpendicular to the rotation axis C. The sub pole 14 does not have the coil 7, and the electric wires of the coil 7 are not wound around the sub pole 14. Note that, as shown in the second embodiment described later, a sub pole vane portion 16 can be formed at the front end of the sub pole 14. Further, a slit 17 of a prescribed width is provided between the vane portion 13 of the tooth 11 and the sub pole 14. Thereby, the slit width W in the winding direction of the coil 7 (the extension direction of the column portion 12 and the radial direction of the rotor 6) is secured.

[0068] Figure 4 is a diagram showing the magnet angle θ M and the vane angle θ W of the brush motor 1. In a cross section perpendicular to the rotation axis C, the range in which the magnetization region of one magnet pole 5 substantially covers the rotor 6 is expressed in terms of the angle with respect to the rotation axis C, and is referred to as the magnet angle θ M . For example, as shown in Figure 4 , in the case where the magnet 4 is divided into a plurality of magnet poles 5 (a plurality of magnet segments), in a cross section perpendicular to the rotation axis C, the central angle of the sector surrounded by the magnet pole 5 and the line segment connecting from both end portions of the magnet pole 5 to the rotation axis C is defined as the magnet angle θ M . Further, in the case where the magnet 4 is a ring-shaped magnet, the range in which the magnetic force appears in the radial direction without including the non-magnetization region is expressed in terms of the angle with respect to the rotation axis C, and is defined as the magnet angle θ M .

[0069] Note that, for both end portions of the magnetization region in the case where a plurality of magnetic poles are magnetized on the annular magnet, one magnet piece, the angle from the center position of each magnetic pole (magnetization center position) at which the magnetic flux density decreases and the magnetic flux density becomes 0 for the first time is made. In Figure 14 the relationship between the magnetic flux density distribution of the annular magnet and the magnet angle θ M is exemplified. Figure 14 the angle θ0~θ 12 at which the magnetic flux density becomes 0 is shown. As shown in Figure 14 the periphery of 0° (θ0~θ1), 90° (θ2~θ4), 180° (θ5~θ7), and 270° (θ8~θ 10 ) corresponding to the switching positions of adjacent magnetic poles, a non-magnetization region or a minute polarity reversal region is sometimes generated, but the range is excluded from the definition of the magnet angle θ M . In Figure 14 the angle range from the point at which the absolute value of the magnetic flux density exceeds 0 to the point at which the center position of each magnetic pole is included and the magnetic flux density becomes 0 again, such as θ1~θ2, θ4~θ5, θ7~θ8, θ 10 ~θ 11 , is defined as the magnet angle θ M . In summary, in the cross section perpendicular to the rotation axis C, the angle of the magnetization region of one magnet pole 5 with respect to the rotation axis C is defined as the magnet angle θ M .

[0070] In addition, in the cross section perpendicular to the rotation axis C, the range in which one vane portion 13 opposes the magnet 4 is expressed in terms of the angle with respect to the rotation axis C, and is referred to as the vane angle θ W . That is, in the cross section perpendicular to the rotation axis C, the central angle of the sector surrounded by the vane portion 13 and the line segment connecting from both end portions of the vane portion 13 to the rotation axis C is defined as the vane angle θ W . In the brush motor 1 of the first embodiment, the vane angle θ W is preferably set to be larger than the magnet angle θ M . (θ W ≥ θ M ). Thus, the magnet flux is easily picked up by the teeth 11, and the flux is effectively utilized.

[0071] Figure 5 is a circuit diagram showing the structure of the power supply circuit 23. The s number of coils 7 are connected in a ring shape. In Figure 5 , the three coils 7 are connected in a delta connection (delta connection). In addition, the c number (six in Figure 5 ) of commutator segments 9 are connected in short circuit with respect to the ring-shaped coil circuit every 360 / p degrees (every 180 degrees in Figure 5 ) with respect to the rotation angle of the rotor 6. Note that,Figure 5 C1 to C6 in the diagram represent six commutator segments 9. For example, in... Figure 5 In the loop-shaped coil circuit shown, point P1 between the first and second coils is short-circuited to commutator segments C1 and C4. These commutator segments C1 and C4 are positioned 180 degrees offset from the rotation axis C. Therefore, the potential at point P1 is the same for every half-turn of the rotation axis C. Similarly, point P2 between the second and third coils is short-circuited to commutator segments C2 and C5, and point P3 between the third and first coils is short-circuited to commutator segments C3 and C6.

[0072] Figure 5 In the diagram, B1 and B2 represent two brushes 21. The positions of brushes B1 and B2 are offset by 90 degrees relative to the rotation axis C. One brush 21 is connected to the positive terminal of the power supply, and the other brush 21 is connected to the negative terminal. Brushes B1 and B2 are connected to any one of the commutator segments C1 to C6. The commutator segments 9 connected to the brushes 21 vary according to the rotation angle. For example, the combination of commutator segments 9 connected to brushes B1 and B2 changes as the rotor 6 rotates, such as (C6C1, C2), (C1, C2), (C1C2, C3), (C2, C3)... This circuit structure allows the rotor 6 to be driven to rotate appropriately with high torque.

[0073] [B. Function / Effect]

[0074] Figure 6 Figure (A) shows a brushed motor (four poles, six slots) as a comparative example. In this brushed motor, the number of coils 7 is more than in the first embodiment, being six; the number of pairs p of magnet poles 5 is the same as in the first embodiment, being two pairs; and the magnet angle θ... M Less than 90 degrees. On the other hand, the number of coils is six, therefore the blade angle θ... W The maximum angle is only 60 degrees, blade angle θ W Comparison of magnet angle θ M The magnetic flux is too small. As a result, the magnetic flux is not picked up sufficiently and cannot be used effectively.

[0075] In contrast, in the brushed motor 1 (four poles, three slots) of the first embodiment, the number of coils is three, therefore, as Figure 6 As shown in (B), the blade angle θ W The area of ​​the blade portion 13 relative to the magnetic pole 5 of the magnet is increased. As a result, the magnetic flux of the magnet is easily picked up by the tooth 11, and the magnetic flux is effectively utilized.

[0076] Figure 7Figure (A) shows a brushed motor (without auxiliary poles) as a comparative example. When the iron core 10 lacks auxiliary poles 14, the flow of magnetic flux supplied to the iron core 10 from the magnet poles 5 becomes intermittent, and vibration (cogging effect) tends to increase. For example, when the wider portion of the slit 17 is opposite the magnet poles 5, Figure 7 The magnetic flux indicated by the hollow arrow in (A) does not act on the iron core 10. Furthermore, eddy currents may be generated in the outer shell 2, increasing losses. Consequently, the permeability decreases, and demagnetization may become more likely.

[0077] In contrast, the brushed motor 1 in the first embodiment is provided with an auxiliary pole 14, and the slit 17 is relatively narrow, thus ensuring continuous magnetic flux flow. For example, as Figure 7 As shown by the black arrow in (B), even when the auxiliary pole 14 and slit 17 are partially opposite to the magnet pole 5, the magnetic flux still acts on the iron core 10. This easily reduces vibration (cogging effect). Furthermore, eddy currents are less likely to be generated in the outer casing 2, resulting in smaller losses. Additionally, the permeability increases, making demagnetization less likely, and the winding rotor balance is also improved.

[0078] According to the brushed motor 1 of the first embodiment, the following effects are obtained.

[0079] (1) In the brushed motor 1 of the first embodiment, the values ​​of p, s, and c are set such that 0.5 < p / s < 1 and s < c holds true. Therefore, compared with, for example... Figure 6 Compared to the existing brushed motor shown in (A), the size of the brushed motor 1 can be easily miniaturized, or high torque can be achieved with the same size (same volume). Furthermore, the blade portion 13 of the tooth 11 can easily be positioned opposite the magnetic pole 5 of the magnet with a sufficiently large area, thus effectively utilizing the magnetic flux. Therefore, the magnetic flux of the magnet can be fully collected, and miniaturization and high torque can be achieved with a simple structure.

[0080] Furthermore, compared to existing brushed motors, the width direction of the slit 17 is nearly parallel to the winding direction of the winding, thus increasing the net slit width W and making it easier to wind the winding. In addition, winding time is reduced, which can reduce the effort and cost of manufacturing.

[0081] (2) In the brushed motor 1 of the first embodiment, as follows Figure 6 As shown in (B), the blade angle θ W For the magnet angle θ M The above dimensions ensure that the opposing area of ​​the blade section 13 relative to the magnet pole 5 can reliably and effectively utilize magnetic flux. Furthermore, the blade angle θ... W Less than the magnet angle θ M Compared to the previous situation, this can reduce vibration (groove effect). Furthermore, by increasing the blade angle θ... WThis allows for an increase in the slit width W, making it easier to wind the windings.

[0082] (3) In the brushed motor 1 of the first embodiment, as follows Figure 7 As shown in (B), an auxiliary pole 14 is provided. By providing such an auxiliary pole 14, the flow of magnetic flux transferred between the magnet pole 5 and the iron core 10 can be made continuous, and vibration (cogging effect) can be reduced. In addition, the generation of eddy currents in the outer casing 2 can be prevented, and losses can be reduced. Furthermore, the permeability can be increased and demagnetization is less likely, and the winding rotor balance can be improved.

[0083] (4) In the brushed motor 1 of the first embodiment, as Figure 5 As shown, the coil 7 is connected in a loop. Furthermore, each commutator segment 9 is short-circuited to the loop coil circuit every 180 degrees (every 360 / p degrees) of rotation angle with respect to the rotor 6. With this circuit structure, compared to existing brushed motors, the number of brushes can be reduced to 1 / p, making it easy to miniaturize the brushed motor 1 and achieving miniaturization and high torque with a simple structure.

[0084] (5) In the brushed motor 1 of the first embodiment, two pairs of magnet poles 5, three coils 7, and six commutator segments 9 are provided, and the combination of (p, s, c) is (2, 3, 6). With such a structure, a high-torque brushed motor 1 can be realized with a simple structure with fewer coils. In addition, it is easy to miniaturize due to the increase in magnetic flux.

[0085] [2. Second Embodiment]

[0086] Figure 8 This is a cross-sectional view showing the structure of the brushed motor 41 as a second embodiment. For convenience, the cross-sectional view of the commutator segments 9 is shown overlapping the cross-sectional views of the stator 3 and rotor 6. Elements corresponding to those described in the first embodiment are labeled with the same reference numerals, and descriptions are omitted where appropriate. This brushed motor 41 has three pairs of magnet poles 5, four coils 7, and twelve commutator segments 9. The combination of (p, s, c) is (3, 4, 12), making it a six-pole, four-slot motor.

[0087] The auxiliary pole 14 of the iron core 10 of the brushed motor 41 in the second embodiment has an auxiliary pole post portion 15 and an auxiliary pole blade portion 16. For example... Figure 8The auxiliary pole 14 is shown to have a pole column portion 15 and an auxiliary pole blade portion 16. The pole column portion 15 is a portion extending toward the radial outer side of the rotor 6. The auxiliary pole blade portion 16 is a curved surface-shaped (arc surface-shaped or a similar shape) portion spreading from the outer end portion of the pole column portion 15 in the circumferential direction of the rotor 6, and is arranged so as to face the magnet pole 5 in a non-contact manner. Note that the auxiliary pole 14 does not have the coil 7, and the electric wire of the coil 7 is not wound around the auxiliary pole 14. Further, the auxiliary pole blade portion 16 can be omitted, and the auxiliary pole 14 can be formed in the same shape as that of the first embodiment.

[0088] Figure 9 FIG. 6 is a diagram showing the magnet angle θm M and the blade angle θb W of the brush motor 41. In the brush motor 41 of the second embodiment, the blade angle θb W is also preferably set to the size of the magnet angle θm M (θb W ≥ θm M ). Thereby, the magnetic flux of the magnet is easily picked up by the teeth 11, and the magnetic flux is effectively utilized.

[0089] Each of the commutator segments 9 is connected to each of the coils 7 through the power supply circuit 42. Figure 10 FIG. 7 is a circuit diagram showing the structure of the power supply circuit 42. The four coils 7 are connected in a ring shape. Further, the twelve commutator segments 9 are connected in short to the ring-shaped coil circuit at every 360 / p degrees (i.e., every 120 degrees) with respect to the rotation angle of the rotor 6. For example, on the ring-shaped coil circuit shown in FIG. 7, the point Ql between the first coil and the second coil is connected in short to the commutator segments Cl, C5, C9. Figure 10

[0090] The positions of these commutator segments Cl, C5, C9 become positions that are shifted by 120 degrees with respect to the rotation axis C. Therefore, the potential of the point Ql is the same every time the rotation axis C rotates by one-third. Similarly, the point Q2 between the second coil and the third coil is connected in short to the commutator segments C2, C6, C 10 . Further, the point Q3 between the third coil and the fourth coil is connected in short to the commutator segments C3, C7, C 11 , and the point Q4 between the fourth coil and the first coil is connected in short to the commutator segments C4, C8, C 12 . Further, the positions of the brushes Bl, B2 become positions that are shifted by 180 degrees with respect to the rotation axis C.

[0091] ​According to the brush motor 41 of the second embodiment, the same effects as the first embodiment can be obtained. For example, miniaturization can be easily achieved compared with the conventional brush motor, or high-torque can be achieved with the same size. In addition, high torque can be obtained compared with the brush motor 1 of the first embodiment. On the other hand, compared with the conventional brush motor (for example, a six-pole twelve-slot brush motor) having the same number of magnetic poles 5 and a larger number of coils, the winding time is reduced by the concentrated winding structure, and the time and cost taken for manufacturing can be reduced. Also, the coil end can be reduced by the concentrated winding structure, and the winding resistance can be reduced. Furthermore, compared with the first embodiment, the pulsation of current can be increased, and sensorless control using the pulsation of current can be performed without using a separate sensor magnet.

[0092] [3. Third Embodiment]

[0093] Figure 11 is a cross-sectional view showing the structure of a brush motor 51 as a third embodiment. Here, for convenience, the cross-sectional view of the commutator segment 9 is shown overlapping the cross-sectional views of the stator 3 and the rotor 6. For elements corresponding to those described in the first embodiment, the same reference numerals are assigned and appropriate description is omitted. In the brush motor 51, three pairs of magnetic poles 5, five coils 7, and fifteen commutator segments 9 are provided. The combination of (p, s, c) is (3, 5, 15), which is a six-pole five-slot motor. Note that in the core 10 of the brush motor 51 of the third embodiment, the auxiliary pole 14 is omitted. Thereby, the slit width W between the adjacent vane portions 13 is secured, and a structure in which the wire of the coil 7 is easily wound is obtained.

[0094] Figure 12 is a diagram showing the magnetic pole angle θ M and the vane angle θ W of the brush motor 51. In the brush motor 51 of the third embodiment, the vane angle θ W is also preferably set to the size of the magnetic pole angle θ M or more (θ W ≥ θ M ). Thereby, the magnetic flux is easily picked up by the teeth 11, and the magnetic flux is effectively utilized.

[0095] Each of the commutator segments 9 is connected to each of the coils 7 through a power supply circuit 52. Figure 13 is a circuit diagram showing the structure of the power supply circuit 52. The five coils 7 are connected in a ring shape. In addition, the fifteen commutator segments 9 are connected in short circuit to the ring-shaped coil circuit at every 360 / p degrees (i.e., every 120 degrees) with respect to the rotation angle of the rotor 6. For example, in the case of the brush motor 51 of the third embodiment, the commutator segments 9 are connected in short circuit to the coil circuit at every 120 degrees with respect to the rotation angle of the rotor 6. Figure 13The point R1 between the first coil and the second coil on the illustrated annular coil circuit is connected to the commutator segments C1, C6, C 11 short-circuited.

[0096] These commutator segments C1, C6, C 11 are positioned at positions that are offset by 120 degrees with respect to the rotation axis C. Therefore, the potential at the point R1 is the same at one-third of the rotation of the rotation axis C. Similarly, the point R2 between the second coil and the third coil is connected to the commutator segments C2, C7, C 12 short-circuited. In addition, the point R3 between the third coil and the fourth coil is connected to the commutator segments C3, C8, C 13 short-circuited, and the point R4 between the fourth coil and the fifth coil is connected to the commutator segments C4, C9, C 14 short-circuited, and the point R5 between the fifth coil and the first coil is connected to the commutator segments C5, C 10 , C 15 short-circuited. In addition, the positions of the brushes B1, B2 are positions that are offset by 180 degrees with respect to the rotation axis C.

[0097] The brush motor 51 according to the third embodiment can achieve the same effects as the first embodiment and the second embodiment. For example, compared with a conventional brush motor, miniaturization can be easily achieved, or high torque can be achieved with the same size. In addition, compared with the brush motors 1, 41 of the first embodiment and the second embodiment, high torque can be achieved. Furthermore, compared with the first embodiment and the second embodiment, pulsation of torque can be reduced, vibration can be reduced, and controllability can be improved.

[0098] [4. Other]

[0099] The above-described embodiments are merely examples and are not intended to exclude various modifications and technical applications that are not explicitly shown in the embodiments. The structures of the embodiments can be variously modified without departing from the spirit of the embodiments. In addition, the structures of the embodiments can be selected as needed, or can be appropriately combined with various structures included in known technology.

Claims

1. A brush motor characterized by comprising: a rotor core provided to a rotor; s teeth provided to the rotor core; s concentrated-winding coils each of which is wound with an electric wire around s teeth; a commutator provided to the rotor in a manner that the commutator cannot rotate relatively to the rotor; c commutator segments provided to the commutator and connected to the coils; p pairs of magnetic poles provided to a stator and arranged opposite to the teeth; and a brush in sliding contact with the commutator segments to supply electric current to the coils, the following inequality A and inequality B are satisfied, Inequality A: 0.5 < p / s < 1, Inequality B: s < c, where s = 4 or s = 5, the teeth have a blade portion formed in a curved surface shape extending in a rotation direction of the rotor along a surface of the magnetic pole, the magnetic pole is formed in a curved surface shape opposite to the blade portion, in a cross section perpendicular to a rotation axis of the rotor, a central angle of a sector enclosed by the blade portion and a line segment connecting both end portions of the blade portion to the rotation axis is defined as a blade angle, an angle formed by a magnetization region of one of the magnetic poles and the rotation axis is defined as a magnetic pole angle, and the blade angle is equal to or greater than the magnetic pole angle.

2. The brush motor according to claim 1, characterized by comprising at least one auxiliary pole provided integrally to the rotor core between adjacent ones of the coils, extending radially from a rotation center of the rotor to strengthen a flow of magnetic flux, and not having a coil.

3. The brush motor according to claim 1 or 2, characterized by comprising a power supply circuit that connects the s coils in a ring shape and connects the c commutator segments to each other in short circuit at intervals of 360 / p degrees with respect to a rotation angle of the rotor.

4. The brush motor according to claim 1 or 2, characterized in that the p is 3, the s is 4, and the c is 12.

5. The brush motor according to claim 1 or 2, characterized in that the p is 3, the s is 5, and the c is 15. ​ ​ ​ ​ ​ ​

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