motor

Abstract

The motor (10) includes a rotating shaft (12), an armature core (26), a plurality of coils (28), a commutator (24), and a brush (18). Furthermore, the number of turns of any of the coils (28) arranged on the outer side in the rotational radial direction relative to the coil (28) arranged on the innermost side in the rotational radial direction is set to be greater than the number of turns of the coil (28) arranged on the innermost side in the rotational radial direction.

Description

[0001] Cross-reference to related applications

[0002] This application is based on Japanese Patent Application No. 2020-052997 filed on March 24, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a motor. Background Art

[0004] Patent Document 1 below discloses a DC motor used as an actuator in an automobile. In the motor described in this document, the current flowing to the motor windings (multiple coils) that form part of the armature is switched by brushes and a commutator. Furthermore, the motor described in this document generates a desired frequency signal by varying the number of conductors (the number of turns) in the motor windings for each coil.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5306346. Summary of the Invention

[0008] However, in the structure described in Patent Document 1, sparks may sometimes occur between the armature and the commutator depending on the number of conductors (coil turns) in the motor winding. This sparking may increase brush wear and cause abnormal noise.

[0009] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a motor capable of suppressing the generation of sparks between a brush and a commutator.

[0010] The motor of the first aspect of the present disclosure comprises:

[0011] a rotating shaft supported so as to be rotatable;

[0012] an armature core configured to rotate integrally with the rotating shaft;

[0013] a plurality of coils formed by annularly winding conductive wires around the armature core and arranged side by side in the rotational circumferential direction, wherein the number of turns of any of the coils arranged radially outward relative to the coil arranged radially innermost is set to be greater than the number of turns of the coil arranged radially innermost;

[0014] a commutator, the commutator being configured to rotate integrally with the rotating shaft and being connected to the windings forming the plurality of coils; and

[0015] A brush is provided in contact with the commutator and can switch the current supply to each of the coils by sliding with the commutator that rotates together with the rotating shaft.

[0016] By adopting the above configuration, it is possible to suppress the occurrence of sparks between the brushes and the commutator. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description.

[0018] Figure 1 It is a plan view showing the motor according to this embodiment.

[0019] Figure 2 It schematically represents the composition Figure 1 A schematic diagram showing wiring, etc., of an armature of a portion of the motor shown.

[0020] Figure 3 This is a graph for explaining the energy of sparks generated between the brushes and the commutator.

[0021] Figure 4 This is a graph showing the relationship between coil numbers and coil inductance.

[0022] Figure 5 This is a graph showing the relationship between coil numbers and coil resistance.

[0023] Figure 6 This is a graph showing the relationship between coil numbers and the number of coil turns.

[0024] Figure 7A This diagram schematically illustrates the direction and magnitude of the current after commutation when the rotor rotates.

[0025] Figure 7B It is a schematic diagram that schematically shows the direction and magnitude of the current after commutation when the rotor rotates, which indicates the rotation ratio of the rotor. Figure 7A A further state.

[0026] Figure 7C It is a schematic diagram that schematically shows the direction and magnitude of the current after commutation when the rotor rotates, which indicates the rotation ratio of the rotor. Figure 7B A further state.

[0027] Figure 7D It is a schematic diagram that schematically shows the direction and magnitude of the current after commutation when the rotor rotates, which indicates the rotation ratio of the rotor. Figure 7C A further state.

[0028] Figure 7EIt is a schematic diagram that schematically shows the direction and magnitude of the current after commutation when the rotor rotates, which indicates the rotation ratio of the rotor. Figure 7D A further state.

[0029] Figure 8 This is a graph showing the spark energy of the motor of the present embodiment and the spark energy of the motor of the comparative example.

[0030] Figure 9 This is a graph showing another example of the relationship between the coil number and the number of coil turns.

[0031] Figure 10 This diagram schematically shows wiring of an armature constituting a portion of a motor of another example. Figure 2 Corresponding schematic diagram. DETAILED DESCRIPTION

[0032] use Figure 1 as well as Figure 2 , a motor 10 according to an embodiment of the present disclosure will be described. The arrows Z, R, and C, as indicated in the figures, respectively, indicate the axial direction, radial direction, and circumferential direction of the rotating shaft 12 of the motor 10. Furthermore, when only the axial, radial, and circumferential directions are indicated, these directions, unless otherwise specified, represent the axial, radial, and circumferential directions of the rotating shaft 12.

[0033] like Figure 1 as well as Figure 2 As shown, the motor 10 of this embodiment is a four-pole slotted DC motor including a stator 14 , a rotor 16 , and a pair of brushes 18 .

[0034] like Figure 2 As shown, the stator 14 is constructed, for example, by fixing a plurality of magnets 20 to one radial side surface of a cylindrical housing. The stator 14 of this embodiment is constructed to include four magnets 20. In this embodiment, magnets 20N with radially inner north poles and magnets 20S with radially inner south poles are arranged at equal intervals along the circumferential direction.

[0035] like Figure 1 as well as Figure 2 As shown, the rotor 16 is arranged radially inward of the stator 14. The rotor 16 is configured to include: a rotating shaft 12, which is rotatably supported by a bearing (not shown); an armature 22 and a commutator 24 (see FIG. Figure 2 ), the armature 22 and the commutator 24 are fixed to the rotating shaft 12.

[0036] like Figure 1As shown, the armature 22 includes an armature core 26 formed using a magnetic material and a plurality of coils 28 formed around the armature core 26 .

[0037] The armature core 26 includes an axial core 30, which forms the radially inner portion of the armature core 26. The rotating shaft 12 is fixed to the center of the axial core 30 by press-fitting or the like. Furthermore, the armature core 26 includes a plurality (ten in this embodiment) of pole teeth 32, which protrude radially outward from the axial core 30 and form a generally T-shape when viewed from the axial direction. The plurality of pole teeth 32 are arranged at equal intervals in the circumferential direction.

[0038] Here, the plurality of pole teeth 32 are numbered sequentially along the circumferential direction. The numbers are indicated by adding parentheses at the end of the symbol "32" representing each pole tooth 32. The numbers are referred to as "pole tooth number".

[0039] In addition, a pair of adjacent pole teeth 32 in the circumferential direction is referred to as a "slot". In this embodiment, ten slots are formed. In addition, the plurality of slots are sequentially labeled "S1 to S10" along the circumferential direction. The slot between the first pole tooth 32 (1) and the second pole tooth 32 (2) is labeled "S1". The slot between the second pole tooth 32 (2) and the third pole tooth 32 (3) is labeled "S2". Similarly, each slot is labeled "S3 to S10" below.

[0040] The plurality of coils 28 are formed by winding conductive wires in a ring shape around the armature core 26 .

[0041] Specifically, the first coil 28 (1) is formed by winding the wire around the second pole tooth portion 32 (1) and the third pole tooth portion 32 (3) between the slot S1 and the slot S3. The first coil 28 (1) is located at a position corresponding to the radially inner end of the second pole tooth portion 32 (1) and the third pole tooth portion 32 (3). In addition, the number indicated in parentheses after the symbol "28" representing the coil 28 is referred to as the "coil number."

[0042] Furthermore, the second coil 28(2) is formed by winding the wire around the third pole tooth portion 32(3) and the fourth pole tooth portion 32(4) between the slots S2 and S4. One circumferential side of the second coil 28(2) is located at a position corresponding to the radially inner end of the fourth pole tooth portion 32(4). Furthermore, the other circumferential side of the second coil 28(2) is located radially outward relative to the one circumferential side of the first coil 28(1).

[0043] Furthermore, the third coil 28(3) is formed by winding the wire around the fourth pole tooth portion 32(4) and the fifth pole tooth portion 32(5) between the slots S3 and S5. One circumferential side of the third coil 28(3) is located at a position corresponding to the radially inner end of the fifth pole tooth portion 32(5). Furthermore, the other circumferential side of the third coil 28(3) is located radially outward relative to the circumferential side of the second coil 28(2).

[0044] Furthermore, the fourth coil 28 (4) is formed by winding the wire around the fifth pole tooth portion 32 (5) and the sixth pole tooth portion 32 (6) between the slots S4 and S6. One circumferential side of the fourth coil 28 (4) is located at a position corresponding to the radially inner end of the sixth pole tooth portion 32 (6). Furthermore, the other circumferential side of the fourth coil 28 (4) is located radially outward relative to the circumferential side of the third coil 28 (3).

[0045] Furthermore, the fifth coil 28(5) is formed by winding the wire around the sixth pole tooth portion 32(6) and the seventh pole tooth portion 32(7) between the slots S5 and S7. The fifth coil 28(5) is located at a position corresponding to the radially outer ends of the sixth pole tooth portion 32(6) and the seventh pole tooth portion 32(7), and is located radially outward relative to one circumferential side of the fourth coil 28(4) and the other circumferential side of the sixth coil 28(6).

[0046] Furthermore, the sixth coil 28(6) is formed by winding the wire around the seventh pole tooth 32(7) and the eighth pole tooth 32(8) between the slots S6 and S8. The sixth coil 28(6) is located at a position corresponding to the radially inner end of the seventh pole tooth 32(7) and the eighth pole tooth 32(8).

[0047] Furthermore, the seventh coil 28 (7) is formed by winding the wire around the eighth pole tooth portion 32 (8) and the ninth pole tooth portion 32 (9) between the slots S7 and S9. One circumferential side of the seventh coil 28 (7) is located at a position corresponding to the radially inner end of the ninth pole tooth portion 32 (9). Furthermore, the other circumferential side of the seventh coil 28 (7) is located radially outward relative to one circumferential side of the sixth coil 28 (6).

[0048] Furthermore, the eighth coil 28 (8) is formed by winding the wire around the ninth pole tooth portion 32 (9) and the tenth pole tooth portion 32 (10) between the slots S8 and S10. One circumferential side of the eighth coil 28 (8) is located at a position corresponding to the radially inner end of the tenth pole tooth portion 32 (10). Furthermore, the other circumferential side of the eighth coil 28 (8) is located radially outward relative to the circumferential side of the seventh coil 28 (7).

[0049] Furthermore, the ninth coil 28 (9) is formed by winding the wire around the tenth pole tooth portion 32 (10) and the first pole tooth portion 32 (1) between the slot S9 and the slot S1. One circumferential side of the ninth coil 28 (9) is located at a position corresponding to the radially inner end of the first pole tooth portion 32 (1). Furthermore, the other circumferential side of the ninth coil 28 (9) is located radially outward relative to one circumferential side of the eighth coil 28 (8).

[0050] Furthermore, the tenth coil 28 (10) is formed by winding the wire around the first pole tooth portion 32 (1) and the second pole tooth portion 32 (2) between the slot S10 and the slot S2. The tenth coil 28 (10) is located at a position corresponding to the radially outer ends of the first pole tooth portion 32 (1) and the second pole tooth portion 32 (2), and is located radially outward relative to one circumferential side of the ninth coil 28 (9) and the other circumferential side of the first coil 28 (1).

[0051] Here, the first coil 28 (1) and the sixth coil 28 (6) are configured to be point-symmetrical with respect to the rotation center axis. In addition, the second coil 28 (2) and the seventh coil 28 (7) are configured to be point-symmetrical with respect to the rotation center axis. In addition, the third coil 28 (3) and the eighth coil 28 (8) are configured to be point-symmetrical with respect to the rotation center axis. In addition, the fourth coil 28 (4) and the ninth coil 28 (9) are configured to be point-symmetrical with respect to the rotation center axis. In addition, the fifth coil 28 (5) and the tenth coil 28 (10) are configured to be point-symmetrical with respect to the rotation center axis. Therefore, in the following description, the sixth coil 28(6), the seventh coil 28(7), the eighth coil 28(8), the ninth coil 28(9), and the tenth coil 28(10) are sometimes described as coils that are the same as or correspond to the first coil 28(1), the second coil 28(2), the third coil 28(3), the fourth coil (4), and the fifth coil 28(5), respectively.

[0052] like Figure 2 As shown, the commutator 24 is configured to include: a fixing portion (not shown) fixed to the rotating shaft 12 (see Figure 1); a plurality of commutator segments 34 (ten in this embodiment), each of which is formed using copper plates or the like and fixed to the radially outer surface of the fixing portion. The plurality of commutator segments 34 are arranged at equal intervals along the circumferential direction. Here, the plurality of commutator segments 34 are numbered sequentially along the circumferential direction. Furthermore, this number is indicated by parentheses at the end of the mark 34 representing each commutator segment 34. Furthermore, this number is referred to as the "commutator segment number."

[0053] Here, the ends of the winding forming the first coil 28 (1) are connected to the seventh commutator segment 34 (7) and the eighth commutator segment 34 (8), respectively. In addition, the ends of the winding forming the fifth coil 28 (5) are connected to the first commutator segment 34 (1) and the second commutator segment 34 (2), respectively. In addition, although not shown in the figure, the ends of the winding forming the second coil 28 (2) are connected to the eighth commutator segment 34 (8) and the ninth commutator segment 34 (9), respectively. In addition, the ends of the winding forming the third coil 28 (3) are connected to the ninth commutator segment 34 (9) and the tenth commutator segment 34 (10), respectively. In addition, the ends of the winding forming the fourth coil 28 (4) are connected to the tenth commutator segment 34 (10) and the first commutator segment 34 (1), respectively. Furthermore, the ends of the winding forming the sixth coil 28 (6) are connected to the second commutator segment 34 (2) and the third commutator segment 34 (3), respectively. Furthermore, the ends of the winding forming the seventh coil 28 (7) are connected to the third commutator segment 34 (3) and the fourth commutator segment 34 (4), respectively. Furthermore, the ends of the winding forming the eighth coil 28 (8) are connected to the fourth commutator segment 34 (4) and the fifth commutator segment 34 (5), respectively. Furthermore, the ends of the winding forming the ninth coil 28 (9) are connected to the fifth commutator segment 34 (5) and the sixth commutator segment 34 (6), respectively. Furthermore, the ends of the winding forming the tenth coil 28 (10) are connected to the sixth commutator segment 34 (6) and the seventh commutator segment 34 (7), respectively.

[0054] Furthermore, the second commutator segment 34(2) and the seventh commutator segment 34(7) are electrically connected via a connecting wire 36. Furthermore, the third commutator segment 34(3) and the eighth commutator segment 34(8) are electrically connected via a connecting wire 36. Although not shown, the fourth commutator segment 34(4) and the ninth commutator segment 34(9) are electrically connected via a connecting wire 36. Furthermore, the fifth commutator segment 34(5) and the tenth commutator segment 34(10) are electrically connected via a connecting wire 36. Furthermore, the first commutator segment 34(1) and the fifth commutator segment 34(5) are electrically connected via a connecting wire 36.

[0055] A pair of brushes 18 are provided at positions where they can abut against each commutator segment 34 of the commutator 24 on the radial outside of the commutator 24. The pair of brushes 18 are supported by a brush holder (not shown) so as to limit movement in the circumferential and axial directions and can move in the radial direction. In addition, the pair of brushes 18 are urged toward one side (radially inner side) of the commutator 24 by a spring (not shown) provided in the brush holder. In addition, in the present embodiment, the circumferential position of each brush 18 is set as follows, that is, when one brush 18 (the brush 18 on the positive side) is located at a position corresponding to the circumferential center portion of one commutator segment 34, the other brush 18 (the brush 18 on the negative side) is located at a position corresponding to between a pair of commutator segments 34 adjacent in the circumferential direction. Specifically, the circumferential positions of the brushes 18 are set in such a manner that, when one brush 18 is located at a position corresponding to the circumferential center of the first commutator segment 34 (1), the other brush 18 is located at a position corresponding to between the third commutator segment 34 (3) and the fourth commutator segment 34 (4).

[0056] In the motor 10 of the present embodiment described above, the pair of brushes 18 slides with the segments 34 of the commutator 24 to switch the current flow to the coils 28. This causes the rotor 16 to rotate.

[0057] Here, in Figure 3 The figure shows a graph in which the value and direction of the current flowing through the coil 28 are shown as the vertical axis and time is shown as the horizontal axis. In addition, one side and the other side of the direction of the current flowing through the coil 28 correspond to the positive and negative sides of the vertical axis of the graph, respectively. As shown in the graph, when the direction of the current flowing through the coil 28 is switched, it is ideally switched smoothly as shown by the dotted line L1, but sometimes it is switched sharply as shown by the solid line L2 due to the settings of the individual coils 28 that constitute the armature 22. The amount of change in current per unit time corresponds to the energy (hereinafter referred to as "spark energy") that generates sparks between the brushes 18 and the commutator segments 34 of the commutator 24. If this energy becomes higher, the amount of wear on the brushes 18 and abnormal noise will increase, which is sometimes not preferable from this point of view. In particular, in region A, where the current change per unit time is large, as indicated by the solid line L2, the spark energy increases (the area S represented by the product of the current change and time in region A increases), leading to increased wear of the brush 18 and the generation of abnormal noise. Furthermore, analysis shows that the peak value P1 of the current flowing to one side in region A increases as the inductance of coil 28 increases, while the peak value P2 of the current flowing to the other side in region A increases as the resistance of coil 28 decreases. Taking this into account, the motor 10 of the present disclosure employs the following settings for each coil 28.

[0058] (Setting of Each Coil 28)

[0059] exist Figure 4 2 shows a graph with the inductance of coil 28 plotted on the vertical axis and the coil number plotted on the horizontal axis. The inductance shown by the double-dashed line represents a case where each coil 28 is wound with the same number of turns (34 turns, for example), while the inductance shown by the solid line represents a case where the aforementioned settings for suppressing sparks are applied.

[0060] If each coil 28 is wound with the same number of turns, it is clear that the inductance decreases as the coil number increases from the first to the fifth (sixth to tenth). The difference in inductance between coils 28 is mainly due to the difference in magnetic permeability of the portion (pole teeth 32) that functions as the core of coil 28, among other factors.

[0061] exist Figure 5 2 shows a graph with the resistance of coil 28 plotted on the vertical axis and the coil number plotted on the horizontal axis. The resistance plotted with a two-dot chain line indicates a case where each coil 28 is wound with the same number of turns (34 turns, for example), while the resistance plotted with a solid line indicates a case where the aforementioned settings for suppressing sparks are applied.

[0062] If each coil 28 is wound with the same number of turns, it is clear that the resistance increases as the coil number increases from the first to the fifth (sixth to tenth). The difference in resistance between coils 28 is mainly due to the difference in the length of the winding wire forming coil 28.

[0063] Moreover, if Figure 3 As shown in FIG. 1 , from the perspective of reducing the peak value P1 of the current flowing toward one side in the region A where the amount of change in current per unit time is large, it is effective to reduce the inductance of the coil 28. Furthermore, from the perspective of reducing the peak value P2 of the current flowing toward the other side in the region A, it is effective to increase the resistance of the coil 28. Therefore, as Figure 4 as well as Figure 5 As shown, in this embodiment, the fifth (tenth) coil 28 with the smallest inductance when all coils 28 are wound with the same number of turns is regarded as the turns adjustment coil. Figure 6 As shown, by increasing the number of turns of the fifth (tenth) coil 28 from 34 to 42, the resistance of this coil 28 is increased. Furthermore, by reducing the number of turns of the first to fourth (sixth to ninth) coils 28 from 34 to 32, the inductance of these coils 28 is reduced. Furthermore, by increasing the number of turns of the fifth (tenth) coil 28 from 34 to 42, and reducing the number of turns of the first to fourth (sixth to ninth) coils 28 from 34 to 32, a low-frequency signal can be generated. This meets the demand for sensorless motor 10.

[0064] (Functions and Effects of the Present Embodiment)

[0065] Next, the operation and effects of this embodiment will be described.

[0066] exist 7A to 7E The figure shows the current flowing to each coil 28 via a pair of brushes 18 and a commutator 24 (see Figure 2 ) is a schematic diagram (schematic diagram of the circuit) showing the process of switching (commutation). In addition, the number shown in the quadrilateral box representing the coil 28 is the coil number. In addition, the direction of the current flowing in the circuit C1 located on the left side of the paper relative to the pair of brushes 18 is indicated by the arrow I1, and the magnitude of the current flowing in the circuit C1 on the left is indicated by the thickness of the arrow I1. Moreover, the direction of the current flowing in the circuit C2 located on the right side of the paper relative to the pair of brushes 18 is indicated by the arrow I2, and the magnitude of the current flowing in the circuit C2 on the right is indicated by the thickness of the arrow I2. In addition, the thicker the thickness of the arrows I1 and I2, the larger the current value of the commutated current flowing in the circuits C1 and C2. In addition, the rotation direction of each coil 28 is indicated by the arrow CW.

[0067] like Figure 7A As shown, when the fifth coil 28 (the tenth coil 28), whose resistance has been increased by adjusting the number of turns (turns) described above, forms part of the right-hand circuit C2, the post-commutation current I2 flowing in the right-hand circuit C2, can be reduced compared to the configuration before the number of turns (turns) is adjusted. As a result, when the fifth coil 28 (the tenth coil 28) forms part of the right-hand circuit C2, the post-commutation current I2 flowing in the right-hand circuit C2 can be reduced. As a result, when the fifth coil 28 (the tenth coil 28) forms part of the right-hand circuit C2, the spark energy between the brush 18 and the commutator segments 34 of the commutator 24 can be suppressed from increasing.

[0068] For example, the rotation ratio of each coil 28 Figure 7A The status shown is further Figure 7B As shown, even when the fifth coil 28 (the tenth coil 28) whose resistance is increased by the aforementioned adjustment of the number of turns (turns) does not constitute a part of the circuit C1 on the left side of the post-commutation circuit, the coils 28 other than the fifth coil 28 (the tenth coil 28) also have their inductance reduced by the aforementioned adjustment of the number of turns (turns). As a result, the post-commutation current I1 flowing in the circuit C1 on the left side of the post-commutation circuit (compared to the aforementioned peak value P2 of the current (refer to Figure 3 ) corresponds to) becomes larger than before the number of turns is adjusted, but by reducing the inductance of the coils 28 other than the fifth coil 28 (the tenth coil 28), the peak value P1 of the current mentioned above (refer to Figure 3As a result, even when the fifth coil 28 (the tenth coil 28 ) does not constitute a part of the left circuit C1 , it is possible to suppress the increase in spark energy between the brush 18 and the commutator segment 34 of the commutator 24 .

[0069] For example, the rotation ratio of each coil 28 Figure 7B The status shown is further Figure 7C As shown, when the fifth coil 28 (the tenth coil 28), whose resistance has been increased by adjusting the number of turns (turns) described above, forms part of the right-hand circuit C2, the post-commutation circuit, the post-commutation current I2 flowing in the right-hand circuit C2 can be reduced compared to the configuration before the number of turns (turns) is adjusted. As a result, when the fifth coil 28 (the tenth coil 28) forms part of the right-hand circuit C2, the post-commutation circuit, the spark energy between the brush 18 and the commutator segments 34 can be suppressed. Furthermore, when the fifth coil 28 (the tenth coil 28) forms part of the left-hand circuit C1, the spark energy between the brush 18 and the commutator segments 34 can be similarly suppressed.

[0070] For example, the rotation ratio of each coil 28 Figure 7C The status shown is further Figure 7D As shown, even when the fifth coil 28 (the tenth coil 28) whose resistance is increased by the aforementioned adjustment of the number of turns (turns) does not constitute a part of the circuit C1 on the left side of the post-commutation circuit, the coils 28 other than the fifth coil 28 (the tenth coil 28) also have their inductance reduced by the aforementioned adjustment of the number of turns (turns). As a result, the post-commutation current I1 flowing in the circuit C1 on the left side of the post-commutation circuit (compared to the aforementioned peak value P2 of the current (refer to Figure 3 ) corresponds to) becomes larger than before the number of turns is adjusted, but by reducing the inductance of the coils 28 other than the fifth coil 28 (the tenth coil 28), the peak value P1 of the current mentioned above (refer to Figure 3 As a result, even when the fifth coil 28 (the tenth coil 28 ) does not constitute a part of the left circuit C1 , it is possible to suppress the increase in spark energy between the brush 18 and the commutator segment 34 of the commutator 24 .

[0071] For example, the rotation ratio of each coil 28 Figure 7D The status shown is further Figure 7EAs shown, when the fifth coil 28 (the tenth coil 28), whose resistance has been increased by adjusting the number of turns (turns) described above, forms part of the right-hand circuit C2, the post-commutation current I2 flowing in the right-hand circuit C2, can be reduced compared to the configuration before the number of turns (turns) is adjusted. As a result, when the fifth coil 28 (the tenth coil 28) forms part of the right-hand circuit C2, the post-commutation current I2 flowing in the right-hand circuit C2 can be reduced. As a result, when the fifth coil 28 (the tenth coil 28) forms part of the right-hand circuit C2, the spark energy between the brush 18 and the commutator segments 34 of the commutator 24 can be suppressed from increasing.

[0072] In addition, from Figure 7E Even when the rotation of each coil 28 continues from the state shown, the increase in spark energy between the brush 18 and the commutator segments 34 of the commutator 24 can be suppressed. Furthermore, even when the rotation direction of each coil 28 is opposite to the direction indicated by arrow CW, the increase in spark energy between the brush 18 and the commutator segments 34 of the commutator 24 can be suppressed.

[0073] Here, in Figure 8 Graph 2 shows a comparison of the spark energy accumulated in each coil 28 in configuration S1 before the number of turns is adjusted, and the spark energy accumulated in each coil 28 in configuration S2 after the number of turns has been adjusted as described above. As shown in this graph, in configuration S2 after the number of turns has been adjusted, the spark energy accumulated in the first through fourth coils 28 is reduced compared to configuration S1 before the number of turns has been adjusted. Furthermore, in configuration S2 after the number of turns has been adjusted, the spark energy accumulated in the fifth coil 28 increases compared to configuration S1 before the number of turns has been adjusted. However, the spark energy accumulated in the fifth coil 28 in configuration S2 after the number of turns has been adjusted is reduced compared to the peak value of the spark energy accumulated in each coil 28 (the energy accumulated in the first coil 28) in configuration S1 before the number of turns has been adjusted.

[0074] As described above, by adjusting the number of turns (the number of revolutions) in the manner described above, it is possible to suppress the generation of sparks between the brushes 18 and the segments 34 of the commutator 24 .

[0075] In addition, in this embodiment, the case where the number of turns of the fifth (tenth) coil 28 is increased and the number of turns of the first to fourth (sixth to ninth) coils 28 is reduced to suppress the generation of sparks between the brush 18 and the commutator segments 34 of the commutator 24 is described as an example, but the present disclosure is not limited to this. For example, Figure 9As shown, by increasing the number of turns of the fourth (ninth) coil 28 and reducing the number of turns of the first, second, third and fifth (sixth, seventh, eighth and tenth) coils 28, sparks between the brushes 18 and the commutator segments 34 of the commutator 24 are suppressed.

[0076] In addition, in this embodiment, the example in which the structure for suppressing the generation of sparks between the brush 18 and the commutator segments 34 of the commutator 24 is applied to the motor 10 having four poles and ten slots is described, but the present disclosure is not limited thereto. Figure 10 As schematically shown in the middle portion, a structure for suppressing the generation of sparks between the brushes 18 and the commutator segments 34 of the commutator 24 is applied to a 2-pole 8-slot motor 38 .

[0077] As mentioned above, one embodiment of the present disclosure has been described, but the present disclosure is not limited to the above, and it is obvious that various modifications other than the above can be made and implemented without departing from the scope of the present disclosure.

[0078] In addition, although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-described embodiments and structures. The present disclosure also includes various modifications and variations within the scope of equivalents. In addition, various combinations and methods, including other combinations and methods including only one element, more than one element, or less than one element, also fall within the scope and concept of the present disclosure.

Claims

1. A motor comprising: a rotating shaft supported so as to be rotatable; an armature core configured to rotate integrally with the rotating shaft; a plurality of coils formed by annularly winding conductive wires around the armature core and arranged side by side in the rotational circumferential direction, wherein the number of turns of any of the coils arranged radially outward relative to the coil arranged radially innermost is set to be greater than the number of turns of the coil arranged radially innermost; a commutator, the commutator being configured to rotate integrally with the rotating shaft and being connected to the windings forming the plurality of coils; as well as brushes, the brushes being provided in contact with the commutator and being able to switch the current supply to each of the coils by sliding with the commutator rotating together with the shaft, Assuming that the numbers of turns of the plurality of coils are set to the same, the coil with the smallest inductance is set as the turns adjustment coil. The number of turns of the turns adjustment coil is set to be greater than the number of turns of the other coils. The plurality of coils are three or more pairs of coils that are point-symmetrical with respect to the rotation center axis. Assuming that the number of turns of the plurality of coils is set to be the same, the inductances of the respective pairs of coils are different from each other. Assuming that the numbers of turns of the plurality of coils are set to be the same, a pair of coils with the smallest inductance is set as the turns adjustment coils. The number of turns of the pair of coils serving as the turns adjustment coils is set to be greater than the number of turns of the other pairs of coils, and the inductance of the pair of coils serving as the turns adjustment coils is set to be greater than the inductance of the other pairs of coils.

2. The motor according to claim 1, wherein Among the plurality of coils, a pair of the coils serving as the turn number adjustment coils are arranged at the outermost sides in the rotation radial direction.

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