JP2016077130A - DC motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC motor capable of easily adjusting a position of a magnetic pole center in each of parts of a stator.SOLUTION: A DC motor 10 includes a rotor 12 including: a rotary shaft 18 which is supported in a rotatable manner around an axial line; an armature core 20 which is fixed to the rotary shaft 18 and around which a conductive coil 36 is wound; and a rectifier 22 to which a terminal part of the coil 36 is connected. The DC motor 10 also includes a pair of brushes 44 which slide in contact with the rectifier 22 to electrify the coil 36. Further, the DC motor 10 includes a stator 16 including : a yoke housing 46 covering the armature core 20; and two pairs of N-poole magnets 48N and S-pole magnets 48S which are fixed on an inner peripheral surface of the yoke housing 46 and in which magnetic pole centers L1 and L2 are alternately disposed at unequal intervals in a circumferential direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a DC motor.

  Patent Document 1 below discloses a DC motor. The stator of the DC motor described in this document includes a housing and a ring-shaped magnet fixed to the inner peripheral surface of the housing. The N-pole and S-pole are alternately magnetized along the circumferential direction of the ring-shaped magnet. The N-pole magnetic pole centers and the S-pole magnetic pole centers are arranged at unequal intervals along the circumferential direction. As a result, the current ripple (torque ripple) is increased, and the rotational speed of the DC motor can be detected from the current waveform.

Japanese Patent No. 5026949

  By the way, the ring-shaped magnet described in Patent Document 1 is configured by magnetizing the N pole and the S pole by a magnetic field generator. However, when the N pole and the S pole are magnetized by the magnetic field generator, the positions of the N pole magnetic pole center and the S pole magnetic pole center are likely to vary. That is, the N-pole magnetic pole center and the S-pole magnetic pole center are likely to deviate from a predetermined position.

  An object of the present invention is to obtain a DC motor that can easily adjust the position of the magnetic pole center of each part of the stator in consideration of the above facts.

  The DC motor according to claim 1 is a rotating shaft supported rotatably about an axis, an armature core fixed to the rotating shaft and wound with a conductive winding, and the winding of the winding A rotor having a commutator to which a terminal portion is connected; a pair of brushes that energize the windings by sliding contact with the commutator; a yoke housing that covers the armature core; And a stator having two or more pairs of N-pole magnets and S-pole magnets, which are fixed to the circumferential surface and alternately arranged along the circumferential direction and whose magnetic pole centers are arranged at unequal intervals.

  According to the DC motor of the first aspect, the brush is slidably contacted with the commutator, and energization of the winding wound around the armature core is switched. As a result, a magnetic field is generated around the armature core, and the rotor rotates due to the interaction between the magnetic field and the magnetic field of the stator magnets (N pole magnet and S pole magnet). That is, the rotating shaft of the DC motor rotates. Here, in the present invention, two or more pairs of N-pole magnets and S-pole magnets are fixed to the inner peripheral surface of the yoke housing with the magnetic pole centers arranged at unequal intervals along the circumferential direction. Has been. In this configuration, the position of the magnetic pole center of each part of the stator can be easily adjusted by configuring the stator using segment magnets (N pole magnet and S pole magnet) uniformly magnetized in the circumferential direction. can do. Further, by arranging two or more pairs of N-pole magnets and S-pole magnets at irregular intervals along the circumferential direction, the current ripple when the contact between the brush and the commutator is switched is adjusted to a desired value. be able to.

  The direct current motor according to claim 2 is the direct current motor according to claim 1, wherein the one of the N pole magnets and the one of the S poles arranged adjacent to each other in the circumferential direction of the one N pole magnet. The clearance between the magnet and the clearance between the one N-pole magnet and the S-pole magnet arranged adjacent to the other circumferential side of the one N-pole magnet are different. ing.

  According to the DC motor of the second aspect, the clearance between the one N-pole magnet and the one N-pole magnet and the S-pole magnet adjacent to one side and the other side in the circumferential direction is set as described above. Thereby, the position of the magnetic pole center of each part of the stator can be easily adjusted.

  A DC motor according to claim 3 is the DC motor according to claim 1 or 2, wherein the total number of the N-pole magnets and the S-pole magnets is P, and the number of slots of the armature core is P ×. It is set to a number obtained by (n + 1.5) (n = 1, 2, 3,...).

  According to the DC motor of claim 3, by setting the number of slots of the armature core as described above, the current ripple at the time when the contact between the brush and the commutator is switched while reducing the vibration of the DC motor is obtained. It can be adjusted to a desired value.

  The DC motor according to claim 4 is the DC motor according to any one of claims 1 to 3, wherein the armature core includes a plurality of teeth portions arranged at equal intervals along a circumferential direction. A coil is formed around each of the teeth portions by winding the winding around the teeth portions, and when the rotor rotates, a pair of the The pair of brushes are arranged so that the brush and the circumferential center of the coil do not coincide with each other at the same time.

  According to the DC motor of the fourth aspect, by setting the brush arrangement as described above, the current ripple when the contact between the brush and the commutator is switched can be adjusted to a desired value.

  The DC motor according to claim 5 is the DC motor according to any one of claims 1 to 4, wherein the winding is wound around the armature core by distributed winding.

  According to the DC motor of the fifth aspect, the torque of the DC motor can be improved as compared with the case where the winding is wound around the armature core by concentrated winding.

It is a sectional side view which shows the cross section which cut | disconnected the DC motor of this embodiment along the axial direction. It is an expanded sectional view which expands and shows the cross section of the DC motor cut | disconnected along 2-2 line shown by FIG. It is an expanded sectional view corresponding to FIG. 2 which shows the cross section of the direct-current motor which concerns on contrast. It is a graph which shows the current waveform of the DC motor of this embodiment. It is a graph which shows the current waveform of the direct-current motor which concerns on contrast. It is a graph which shows the current waveform of the direct-current motor which concerns on contrast. It is a graph which shows the current waveform of the direct-current motor which concerns on contrast. It is a table | surface which shows the relationship between the number of slots, the variation of a winding system, and the number of ripple peaks.

  A DC motor according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. In addition, the arrow Z direction, the arrow R direction, and the arrow C direction that are appropriately shown in the drawing indicate the axial direction, the radial direction, and the circumferential direction of the DC motor, respectively. In the following description, when only the axial direction, radial direction, and circumferential direction are indicated, the axial direction, radial direction, and circumferential direction of the DC motor are indicated unless otherwise specified.

  As shown in FIG. 1, the DC motor 10 includes a rotor 12, a brush device 14, and a stator 16.

  The rotor 12 includes a rotating shaft 18 formed in a rod shape, and an armature core 20 and a commutator 22 fixed to the rotating shaft 18. The rotary shaft 18 is disposed coaxially with a yoke housing 46 described later, and one axial end portion of the rotary shaft 18 is rotatably supported on the bottom portion of the yoke housing 46 via the bearing member 24. The other axial end of the rotary shaft 18 is rotatably supported by the motor housing 26 via a substantially cylindrical bearing member 24. A connecting member 28 is press-fitted into the other axial end of the rotating shaft 18.

  As shown in FIG. 2, the armature core 20 is formed using a magnetic material. The armature core 20 is formed in an annular shape and the annular shaft into which the rotary shaft 18 is press-fitted into the shaft center portion. The portion 30 and ten teeth portions 32 that are formed in a substantially T-shape when viewed in the axial direction and are arranged at equal intervals along the circumferential direction. Since the armature core 20 includes ten teeth portions 32, ten slots 34 are formed on the outer peripheral portion of the armature core 20.

  Here, in this embodiment, when the total number of N-pole magnets 48N and S-pole magnets 48S described later is P, the number of slots 34 of the armature core 20 is P × (n + 1.5) (n = 1, 2, 3,...). That is, the number of slots 34 corresponding to P = 4 and n = 1 is set.

  A conductive winding 36 is wound around each tooth portion 32 of the armature core 20. As a result, a coil 38 is formed around the tooth portion 32. Further, in the present embodiment, the winding 36 is wound around each tooth portion 32 of the armature core 20 by distributed winding.

  As shown in FIG. 1, the commutator 22 is fixed to the portion on the other axial end side of the rotating shaft 18 by press fitting or the like. The commutator 22 includes a plurality of commutator pieces 40 arranged at equal intervals along the circumferential direction. Each commutator piece 40 is fixed in a state where adjacent commutator pieces 40 are electrically insulated. Further, each commutator piece 40 is electrically connected to a terminal portion of a corresponding winding 36 wound around each predetermined tooth portion 32 of the armature core 20.

  The brush device 14 is disposed on the radially outer side of the commutator 22. The brush device 14 includes a brush holder 42 formed using an insulating material and a pair of brushes 44 supported by the brush holder 42. And. The pair of brushes 44 is urged radially inward by a spring (not shown). As a result, the pair of brushes 44 can be brought into sliding contact with the commutator 22 to energize the winding 36 (coil 38). Further, as indicated by phantom lines in FIG. 2, the position in the circumferential direction of one brush 44 is arranged at a position shifted by 12 deg to the other side in the circumferential direction with respect to a magnetic pole center L1 of an N-pole magnet 48N described later. The positions of the other brushes 44 in the circumferential direction are arranged at positions shifted by 90 deg to the one side in the circumferential direction with respect to one brush 44. In other words, the circumferential position of the other brush 44 is arranged at a position shifted by 12 deg to the one side in the circumferential direction with respect to the magnetic pole center L2 of the S-pole magnet 48S described later.

  As shown in FIGS. 1 and 2, the stator 16 includes a yoke housing 46 formed in a bottomed cylindrical shape covering the armature core 20, and two pairs of N-pole magnets 48 </ b> N fixed to the yoke housing 46. And an S-pole magnet 48S. The yoke housing 46 includes a cylindrical portion 50 that is disposed to face the armature core 20 in the circumferential direction, and an N-pole magnet 48N and an S-pole magnet 48S are provided on the inner peripheral surface of the cylindrical portion 50. Bonded with an adhesive or the like.

  As shown in FIG. 2, the N-pole magnet 48 </ b> N and the S-pole magnet 48 </ b> S are formed in a plate shape curved in an arc shape corresponding to the inner peripheral surface of the cylindrical portion 50 of the yoke housing 46. The N-pole magnet 48N and the S-pole magnet 48S are uniformly magnetized along the circumferential direction. Further, in the present embodiment, the N-pole magnets 48N and the S-pole magnets 48S are alternately arranged along the circumferential direction, and the magnetic pole centers L1, L2 of the N-pole magnet 48N and the S-pole magnet 48S are arranged. (Centers in the circumferential direction of the N-pole magnet 48N and the S-pole magnet 48S) are arranged at unequal intervals. More specifically, the clearance C1 between one N-pole magnet 48N and the S-pole magnet 48S disposed adjacent to one circumferential side of the one N-pole magnet 48N is equal to one N-pole magnet 48N. It is narrower than the clearance C2 between the magnet 48N and the S-pole magnet 48S disposed adjacent to the other circumferential side of the one N-pole magnet 48N. As a result, the magnetic pole center L1 of one N-pole magnet 48N is circumferential with respect to the magnetic pole center L2 of the S-pole magnet 48S arranged adjacent to one circumferential side of the one N-pole magnet 48N. Is shifted by 78 degrees. In this configuration, the magnetic pole center L1 of the one N-pole magnet 48N is relative to the magnetic pole center L2 of the S-pole magnet 48S arranged adjacent to the other circumferential side of the one N-pole magnet 48N. Is shifted by 102 degrees in the circumferential direction.

(Operation and effect of this embodiment)
Next, the operation and effect of the present embodiment will be described in comparison with the direct current motor 52 according to the comparative example.

  According to the DC motor 10 shown in FIGS. 1 and 2, a pair of brushes 44 is in sliding contact with the commutator piece 40 of the commutator 22 and is wound around the armature core 20 (coil 38). The energization to is switched. As a result, a magnetic field is generated around the armature core 20, and the rotor 12 is rotated by the interaction between the magnetic field and the magnetic field of the segment magnets of the stator 16 (N-pole magnet 48N and S-pole magnet 48S). That is, the rotating shaft 18 of the DC motor 10 rotates.

  Here, in this embodiment, the yoke housing 46 in a state where the two pairs of N-pole magnets 48N and S-pole magnets 48S are alternately arranged along the circumferential direction and the magnetic pole centers L1 and L2 are arranged at unequal intervals. It is fixed to the inner peripheral surface. In this configuration, the stator 16 is configured using segment magnets (N-pole magnet 48N and S-pole magnet 48S) that are uniformly magnetized in the circumferential direction, so that the magnetic pole centers L1 and L1 of the respective parts of the stator 16 can be obtained. The position of L2 can be easily adjusted. Further, by arranging two pairs of N-pole magnets 48N and S-pole magnets 48S at unequal intervals along the circumferential direction, the current when the contact between the brush 44 and the commutator piece 40 of the commutator 22 is switched. The ripple can be adjusted to a desired value. That is, a large current ripple can be obtained as compared with the current ripple of the direct current motor 52 according to the comparative example shown in FIG. In the comparative direct current motor 52 shown in FIG. 3, the magnetic pole center L1 of one N-pole magnet 48N is arranged adjacent to the other circumferential side of the one N-pole magnet 48N. The configuration is the same as that of the DC motor 10 except that the magnetic pole center L2 of the S-pole magnet 48S is shifted by 90 degrees in the circumferential direction. In the DC motor 52, members and portions corresponding to the DC motor 10 are denoted by the same reference numerals as those of the DC motor 10.

  FIG. 4 shows current ripples of the DC motor 10 of the present embodiment, and FIG. 5 shows current ripples of the DC motor 52 in a proportional manner. A waveform obtained by synthesizing the current waveform of the N pole and the current waveform of the S pole shown in the figure is a current ripple. From these figures, it can be seen that the DC motor 10 of this embodiment can obtain a large current ripple as compared with the current ripple of the DC motor 52 according to the comparative example.

  As shown in FIG. 2, in this embodiment, when the total number of N-pole magnets 48N and S-pole magnets 48S is P, the number of slots 34 of the armature core 20 is P × (n + 1. 5) It is set to the number obtained by (n = 1, 2, 3,...). Thereby, in the DC motor 10 of the present embodiment, a large current ripple can be obtained as compared with the current ripple of the DC motor 52 according to the proportionality.

  6 and 7, when the total number of N-pole magnets 48N and S-pole magnets 48S is P, the number of slots 34 of the armature core 20 is P × (n + 2) (n = 1, 2). , 3,...), The current waveform of the direct current motor according to the proportionality set to the number obtained in (3) is shown. 6 except that the number of slots 34 is set to the number obtained by P × (n + 2) (n = 1, 2, 3,...). The configuration is the same as that of the DC motor 10 of the present embodiment. Further, in the direct current motor according to the comparative example showing the current waveform in FIG. 7, the number of slots 34 is set to the number obtained by P × (n + 2) (n = 1, 2, 3,...). The configuration is the same as that of the direct-current motor 52 related to the proportionality. As shown in these figures, when the number of slots 34 is set to the number obtained by P × (n + 2) (n = 1, 2, 3,...), Two pairs of N-pole magnets 48N and S-poles. The current ripple when the magnets 48S are arranged at irregular intervals in the circumferential direction is smaller than the current ripple when two pairs of N-pole magnets 48N and S-pole magnets 48S are arranged at equal intervals in the circumferential direction. I understand that

  As shown in FIG. 2, in this embodiment, the clearance between one N-pole magnet 48N and the one N-pole magnet 48N and the S-pole magnet 48S adjacent to one side and the other side in the circumferential direction. By setting C1 and C2 as described above, the positions of the magnetic pole centers L1 and L2 of each part of the stator 16 can be easily adjusted.

  Further, in the present embodiment, the position of one brush 44 in the circumferential direction is disposed at a position shifted by 12 deg to the other circumferential side with respect to the magnetic pole center L1 of the N-pole magnet 48N, and the other brush 44 is disposed. The position in the circumferential direction is arranged at a position shifted by 12 deg to the one side in the circumferential direction with respect to the magnetic pole center L2 of the S-pole magnet 48S. With this arrangement, the pair of brushes 44 and the circumferential center of the coil 38 do not coincide with each other during the operation of the DC motor 10 (when the rotor 12 is rotating). Thereby, in the DC motor 10 of the present embodiment, a large current ripple can be obtained as compared with the current ripple of the DC motor 52 according to the proportionality.

  Further, in the present embodiment, the winding 36 is wound around each tooth portion 32 of the armature core 20 by distributed winding. Thereby, the torque of the DC motor 10 can be improved as compared with the case where the winding 36 is wound around each of the teeth portions 32 of the armature core 20 by concentrated winding.

  In addition, although this embodiment demonstrated the example which wound the coil | winding 36 to each teeth part 32 of the armature core 20 by distributed winding, this invention is not limited to this. For example, the winding 36 may be wound around each tooth portion 32 of the armature core 20 by concentrated winding. Whether the winding 36 is wound by distributed winding or concentrated winding may be appropriately set in consideration of the torque and dimensions of the DC motor.

  In the present embodiment, the number of slots 34 of the armature core 20 is a number obtained by P × (n + 1.5) (n = 1, 2, 3,...), And P = 4, n = Although an example in which the number of slots 34 corresponding to 1 is set has been described, the present invention is not limited to this. For example, as shown in FIG. 8, n = 2 or more can be set. As shown in this figure, it can be seen that as the value of n is increased, the number of current ripple peaks per unit rotational speed increases. In this figure, the case where n = 0 is shown, but in the configuration where n = 0, the value of the current ripple is large, that is, the current ripple is easy to detect. On the other hand, when the value of n is increased to a value of 1 or more, the value of the current ripple is decreased. However, like the DC motor 10 of the present embodiment, the N pole magnets 48N and the S pole magnets 48S are alternately arranged along the circumferential direction and the magnetic pole centers L1 and L2 are arranged at unequal intervals. The ripple value can be increased.

  Furthermore, in the present embodiment, an example in which the stator 16 is configured using two pairs of N-pole magnets 48N and S-pole magnets 48S has been described, but the present invention is not limited to this. For example, the stator 16 may be configured using three or more pairs of N-pole magnets 48N and S-pole magnets 48S.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications other than the above can be implemented without departing from the spirit of the present invention. Of course.

DESCRIPTION OF SYMBOLS 10 ... DC motor, 12 ... Rotor, 16 ... Stator, 18 ... Rotating shaft, 20 ... Armature core, 22 ... Commutator, 34 ... Slot, 36 ... Winding, 44 ... Brush, 46 ... Yoke housing, 48N ... N-pole magnet, 48S ... S-pole magnet, C1 ... clearance, C2 ... clearance, L1 ... magnetic pole center, L2 ... magnetic pole center

Claims (5)

A rotating shaft supported rotatably about an axis, an armature core fixed to the rotating shaft and wound with a conductive winding, and a commutator to which a terminal portion of the winding is connected A rotor having
A pair of brushes that energize the windings by sliding contact with the commutator;
A yoke housing that covers the armature core, and two or more pairs of N-pole magnets and S-poles that are fixed to the inner peripheral surface of the yoke housing and that are alternately arranged along the circumferential direction and whose magnetic pole centers are unequally spaced A stator having a magnet, and
DC motor equipped with.   A clearance between the one N-pole magnet and the S-pole magnet arranged adjacent to one circumferential side of the one N-pole magnet, the one N-pole magnet, and the one The DC motor according to claim 1, wherein a clearance between the N-pole magnet and the S-pole magnet arranged adjacent to each other in the circumferential direction is different. The total number of the N-pole magnet and the S-pole magnet is P,
3. The DC motor according to claim 1, wherein the number of slots of the armature core is set to a number obtained by P × (n + 1.5) (n = 1, 2, 3,...). The armature core includes a plurality of teeth portions arranged at equal intervals along the circumferential direction,
A coil is formed around each of the teeth portions by winding the winding around the teeth portions,
The pair of brushes are arranged so that the pair of brushes and the circumferential center of the coil do not coincide with each other when the rotor is rotating. The direct current motor as described in the item.   The DC motor according to any one of claims 1 to 4, wherein the winding is wound around the armature core by distributed winding.

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