JP2014018029A - Manufacturing method of rotary electric machine and rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a rotary electric machine capable of easily reducing a cogging torque, and a rotary electric machine.SOLUTION: At least one tooth 25x to which processing for reducing a cogging torque is to be applied is selected from among a plurality of teeth 25. A number of fine recesses 42 are formed on the tip end surface 41 of the selected tooth 25x so that the magnetic resistance based on an air gap between a stator and a rotor is made uniform in the circumferential direction.

Description

  The present invention relates to a method of manufacturing a rotating electrical machine in which a tooth around which a coil is wound is provided on at least one of a stator and a rotor, and the rotating electrical machine.

  Conventionally, such a rotating electric machine, for example, a brushless motor, includes a stator in which a coil is wound around a plurality of teeth provided in a stator core, and a rotor in which a permanent magnet is fixed to the rotor core. In recent years, a brushless motor in which the space factor of the coil is improved by configuring the stator core with a plurality of divided cores divided for each tooth has been proposed (for example, Patent Document 1).

  By the way, in such a brushless motor, the air gap between the stator and the rotor becomes non-uniform due to variations in the dimensional accuracy of the stator core, so that the balance of magnetic resistance based on the air gap is lost and the cogging torque is increased. There is a risk of doing. In particular, in the stator core adopting the split core structure as in Patent Document 1 described above, since roundness, cylindricity, and the like are likely to be lowered due to the effects of assembly errors of the split core, further consideration is required. .

  Therefore, for example, in Patent Document 2, the cogging torque is measured in a state where the stator and the rotor are assembled, and a magnetic body is attached to a predetermined tooth based on the measurement data. The air gap is adjusted to reduce the cogging torque.

JP 2009-56867 A JP 2011-36105 A

  By the way, since the air gap between the stator and the rotor is generally set to be as small as possible, the thickness in the radial direction of the magnetic body used in Patent Document 2 is very thin (for example, several About 10 μm). For this reason, there is a problem that it is difficult to attach the magnetic body and the adjustment work of the air gap becomes complicated. In particular, when the amount of air gap to be adjusted in one tooth is not constant, for example, when the size of the air gap is different between one end and the other end in the circumferential direction of the tooth, the magnetic material whose thickness is not constant Therefore, it is necessary to align and attach the teeth to the teeth with a high degree of accuracy, and the workability may be significantly reduced.

  Such a problem is not limited to the brushless motor as described above, and may also occur in other rotating electrical machines such as a brushed DC motor in which a tooth around which a coil is wound is provided.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a rotating electrical machine and a rotating electrical machine that can easily reduce cogging torque.

  In order to achieve the above object, an invention according to claim 1 includes a stator and a rotor that faces the stator in a radial direction, and at least one of the stator and the rotor is extended in a radial direction. In the method of manufacturing a rotating electrical machine provided with a plurality of teeth around which a coil is wound, a selection step of selecting at least one tooth to be subjected to processing for reducing cogging torque from the plurality of teeth, and the selection Forming a plurality of fine recesses on the tip surface of the teeth selected in the process so that the magnetic resistance based on the air gap between the stator and the rotor is made uniform in the circumferential direction. This is the gist.

  By forming the fine concave portion on the tip end surface of the tooth as in the above configuration, the air gap between the stator and the rotor at the position of the fine concave portion is increased. Therefore, by forming a plurality of such fine recesses in the teeth, it is possible to macroscopically increase the air gap between the stator and the rotor in the teeth portion. And in the said structure, the magnetic resistance based on the air gap between a stator and a rotor is carried out in the circumferential direction by forming a fine recessed part in the tooth selected by the selection process, and adjusting the air gap in this tooth part. Since it is made uniform, the cogging torque can be reduced. Since the air gap is adjusted by forming a fine recess in the tip surface of the tooth as described above, the adjustment work is facilitated as compared with the case where the air gap is adjusted by attaching a thin magnetic body. Furthermore, since the amount of adjustment of the air gap in the teeth can be easily changed by changing the number (density), shape, etc. of the fine recesses according to the position in the teeth, This is particularly effective when the amount of air gap to be adjusted is not constant.

The gist of the second aspect of the present invention is that the fine concave portion is formed by irradiating a pulse laser beam in the method of manufacturing the rotating electric machine according to the first aspect.
According to the above configuration, the fine concave portion is formed by melting and evaporating a part of the teeth by irradiation with the pulse laser beam. Therefore, it can suppress that foreign materials, such as cutting powder, arise with processing of a fine crevice.

  According to a third aspect of the present invention, in the method for manufacturing a rotating electrical machine according to the second aspect, by scanning the pulse laser beam so that the irradiation position of the pulse laser beam draws a circle with a gradually increasing radius. The gist is to form the fine recesses.

  Here, when forming the fine recess, for example, by using a pulse laser beam having a short pulse width (irradiation time) such as a nanosecond pulse laser beam, the portion irradiated with the laser beam is evaporated, It is preferable to use laser processing that hardly transmits heat in the vicinity to suppress the influence of heat on the teeth. However, with such a short irradiation time of the short pulse laser light, the metal in the irradiated portion may not be sufficiently evaporated and may remain melted. Then, the molten metal flows into the portion evaporated by the irradiation of the pulsed laser beam, so that there is a possibility that the formation of the fine recess is hindered. In this regard, in the above configuration, the molten metal is pushed out by scanning the pulse laser beam so that the irradiation position draws a circle with a gradually increasing radius, rather than fixed point irradiation of the pulse laser beam. Therefore, it is possible to efficiently form fine recesses and suppress the influence of heat on the teeth.

  The invention according to claim 4 includes a stator and a rotor that faces the stator in the radial direction, and at least one of the stator and the rotor extends in the radial direction, and a plurality of coils are wound around the stator. In the rotating electrical machine provided with the teeth, at least one tip surface of each of the teeth includes a plurality of magnetic resistances based on an air gap between the stator and the rotor so as to be uniform in the circumferential direction. The gist is that a fine recess is formed. According to the said structure, there can exist an effect similar to Claim 1.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a rotary electric machine and rotary electric machine which can aim at reduction of cogging torque can be provided easily.

The schematic block diagram of an electric power steering device (EPS). Sectional drawing orthogonal to the axial direction of the rotary electric machine of 1st Embodiment. The schematic diagram which shows the dimensional dispersion | variation in the stator core of 1st Embodiment. The fragmentary perspective view of the stator core of 1st Embodiment. (A) is a schematic diagram which shows the selection process which selects the teeth to process in 1st Embodiment, (b) is a schematic diagram which shows the processing process which processes teeth similarly. The schematic diagram which shows the locus | trajectory of the irradiation position of the pulse laser beam of 1st Embodiment. Sectional drawing along the axial direction of the rotary electric machine of 2nd Embodiment.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, in an electric power steering apparatus (EPS) 1, a steering shaft 3 to which a steering wheel 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. Thereby, the rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. The steering shaft 3 is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10. The reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to the knuckle (not shown) via the tie rods 11 connected to both ends of the rack shaft 5, whereby the steering angle of the steered wheels 12, That is, the traveling direction of the vehicle is changed.

  The EPS 1 also includes an EPS actuator (steering force assisting device) 13 that applies assist force for assisting the steering operation to the steering system. The EPS 1 of the present embodiment is configured as a so-called column type EPS that rotationally drives the column shaft 8, and the rotating electrical machine 14 that is the drive source of the EPS actuator 13 is connected to the column shaft via a speed reduction mechanism 15 such as a worm and wheel. 8 is drive-coupled. The rotation of the rotating electrical machine 14 is decelerated by the speed reduction mechanism 15 and transmitted to the column shaft 8 so that the motor torque is applied as an assist force to the steering system.

Next, the configuration of the rotating electrical machine of the present embodiment will be described.
As shown in FIG. 2, the rotating electrical machine 14 is configured as a brushless motor including a stator 22 housed in a cylindrical housing 21 and a rotor 23 that is rotatably supported on the radially inner side of the stator 22. Yes.

  More specifically, the stator 22 includes a cylindrical cylindrical portion 24 fixed to the inner periphery of the housing 21, and a plurality of (in the present embodiment, 12) teeth 25 extending radially inward from the cylindrical portion 24. A stator core 26 is provided. The stator core 26 of the present embodiment is configured by arranging a plurality of divided cores 27 in which the cylindrical portion 24 is divided in the circumferential direction for each tooth 25 in an annular shape. A coil 29 is wound around each tooth 25 by concentrated winding.

  The rotor 23 includes a rotating shaft 31, an annular rotor core 32 that is fixed so as to rotate integrally with the rotating shaft 31, and a plurality (ten in this embodiment) of permanent magnets 33 fixed to the outer peripheral surface of the rotor core 32. And. That is, the rotor 23 of the present embodiment is configured as a so-called surface magnet type rotor.

  The rotating electrical machine 14 configured as described above has a magnetic attractive force and a repulsive force generated between a magnetic field formed by supplying three-phase driving power to each coil 29 and a magnetic flux of the permanent magnet 33. Thus, the rotor 23 is rotated.

  Here, the stator core 26 has a variation in dimensional accuracy due to a manufacturing error or the like, an assembly error of the split core 27, or the like. Therefore, the inner peripheral surface of the stator core 26, that is, the tip surface 41 facing the rotor 23 of the tooth 25 has a slightly distorted shape with respect to the perfect circle, and the air gap between the stator 22 and the rotor 23 is not uniform. May be. Specifically, as shown in FIG. 3, for example, the teeth 25x are inclined with respect to a straight line along the radial direction, and one end in the circumferential direction of the teeth 25x is arranged closer to the rotor 23 than the other end. As a result, the air gap may become non-uniform. As a result, the balance of the magnetic resistance based on the air gap is lost, and the cogging torque may increase.

  Considering this point, as shown in FIG. 4, a large number of fine recesses 42 are formed on the tip surface 41 of the tooth 25 x, and the air gap is adjusted by these fine recesses 42. That is, the air gap between the stator 22 and the rotor 23 at the position of the fine concave portion 42 is increased by forming the fine concave portion 42 on the tip surface 41 of the tooth 25. Therefore, by forming a large number of fine recesses 42, the air gap between the stator 22 and the rotor 23 at the teeth 25x portion is enlarged macroscopically. And in this embodiment, the fine recessed part 42 is formed so that the magnetic resistance based on the air gap between the stator 22 and the rotor 23 may be equalized in the circumferential direction.

  More specifically, each fine concave portion 42 is formed in a round hole shape, and is arranged at a predetermined interval from the adjacent fine concave portion 42. And in the front end surface 41, the number of the fine recessed parts 42 is gradually decreasing from the circumferential direction one end part side where the air gap between the rotors 23 is small toward the other end part side where the air gap is large. In other words, the density of the fine recesses 42 in the tip surface 41 is higher on the one end side in the circumferential direction than on the other end side. In FIG. 4, the number of the fine concave portions 42 is indicated by the density of the point hatching on the tip surface 41, and the illustration of the coil 29 is omitted for convenience of explanation. Thereby, the magnetic resistance based on the air gap between the stator 22 and the rotor 23 is made uniform in the circumferential direction, and the cogging torque is reduced. As an example of such a rotating electrical machine 14, the outer diameter of the stator core 26 is approximately 80 mm, the inner diameter (the distance from the center of the stator core 26 to the tip surface 41 of the teeth 25) is approximately 50 mm, and the axial length thereof is approximately 15 mm. It is possible to set the diameter of the fine recess 42 to about 0.1 mm and the depth to about 0.1 mm for the set one.

Next, manufacture of the rotary electric machine of this embodiment is demonstrated.
In the present embodiment, after the stator 22 is manufactured by arranging the split cores 27 around which the coils 29 are wound in an annular shape, first, at least one tooth 25 that performs processing for reducing cogging torque is selected from the plurality of teeth 25. A selection process for selecting one is performed. Then, the cogging torque is reduced by performing a processing step of forming the fine recesses 42 in the teeth 25 selected in the selection step.

  More specifically, as shown in FIG. 5A, in the selection step, the roundness, cylindricity, and the like of the stator 22 are measured using the shape measuring device 51, and the plurality of teeth 25 are measured based on the measurement result. Teeth 25x (teeth 25x to be processed) protruding radially inward from the inside is selected (selection step). The shape measuring device 51 is a known device that scans the inner circumference of the stator 22 with a measuring unit 52 such as a probe. For details, see, for example, JP-A-7-270153 and JP-A-2006-254519. I want to be. In FIG. 5, the coil 29 is not shown for convenience of explanation.

  Subsequently, as shown in FIG. 5B, in the processing step, the tip portion 41 of the tooth 25x selected in the selection step is irradiated with the pulse laser beam L using the pulse laser processing device 53, thereby forming a fine recess. 42 is formed. In the present embodiment, a nanosecond pulse laser beam is used as the pulse laser beam L. More specifically, as shown in FIG. 6, the fine recesses 42 are formed by scanning the pulsed laser light L so that the irradiation position P of the pulsed laser light L gradually draws a circle having a larger radius. Then, based on the measurement result of the shape measuring device 51, a large number of fine recesses 42 are similarly formed so that the magnetic resistance based on the air gap between the stator 22 and the rotor 23 is made uniform in the circumferential direction. Specifically, as shown in FIG. 3, when one end portion in the circumferential direction of the tooth 25 x is disposed closer to the rotor 23 than the other end portion, the other end side is closer to the one end side in the circumferential direction. The fine recesses 42 are formed so as to have a higher density. In addition, when the distance between the teeth 25x and the rotor 23 is equal over the entire circumferential direction, the density of the fine recesses 42 is formed so as to be uniform over the entire tip surface 41. Thereafter, the rotating electrical machine 14 is manufactured by assembling the rotor 23 inside the stator 22.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When adjusting the air gap by attaching a thin magnetic body in order to adjust the air gap between the stator 22 and the rotor 23 by forming a large number of fine recesses 42 in the tip surface 41 of the tooth 25 Compared to the above, the adjustment work becomes easier. Furthermore, the amount of adjustment of the air gap in the tooth 25 can be easily changed by changing the number (density), shape, and the like of the fine recesses 42 according to the position in the tooth 25. This is particularly effective when the amount of air gap to be adjusted in the teeth 25 is not constant.

  (2) Since the fine recesses 42 are formed by melting and evaporating a part of the teeth 25 by irradiation with the pulsed laser light L, it is possible to suppress the generation of foreign matters such as cutting powder accompanying the processing of the fine recesses 42. .

  (3) Since the nanosecond pulse laser beam is used as the pulse laser beam L, the portion irradiated with the pulse laser beam L in the tooth 25 is evaporated to form the fine concave portion 42, but hardly transfers heat to the vicinity thereof. Thus, the teeth 25 can be processed. For this reason, the influence of the heat given to the teeth 25 can be suppressed.

(4) The fine recesses 42 were formed by scanning the pulsed laser light L so that the irradiation position P draws a circle with a gradually increasing radius, instead of the fixed point irradiation of the pulsed laser light L.
Here, in the short irradiation time of the nanosecond pulse laser beam, the metal in the irradiated portion may not be sufficiently evaporated and may remain melted. Then, the molten metal flows into the portion evaporated by the irradiation of the pulse laser beam L, so that the formation of the fine recess 42 may be hindered. In this regard, since the irradiation position P of the pulse laser beam L is scanned so as to draw a circle having a gradually increasing radius as in the present embodiment, the molten metal is pushed out to the outside. While forming the fine recessed part 42, the influence of the heat given to the teeth 25 can be suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. The main difference between the present embodiment and the first embodiment is that the rotating electrical machine is configured as a brushed DC motor. For this reason, for convenience of explanation, the same components are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

  As shown in FIG. 7, the rotating electrical machine 14 of the present embodiment includes a stator 63 in which a permanent magnet 62 is fixed to the inner periphery of a substantially bottomed cylindrical housing (yoke) 61, and an inner side of the permanent magnet 62. And a rotor (armature) 64 that is rotatably supported.

  More specifically, the rotor 64 includes a rotating shaft 65, and a rotor core 66 and a commutator 67 that are fixed to the rotating shaft 65 so as to be integrally rotatable. The rotor core 66 includes a cylindrical cylindrical portion 68 and a plurality of teeth 69 that extend radially outward from the cylindrical portion 68 in the radial direction. A coil 71 is wound around each tooth 69. Has been. The commutator 67 is configured by fixing a plurality of segments 73 on the peripheral surface of a cylindrical body 72 that rotates integrally with the rotating shaft 65. Corresponding coils 71 are connected to the segments 73, respectively.

  Further, the rotating electrical machine 14 includes a plurality of power supply brushes 75 arranged so as to sandwich the commutator 67 outside the commutator 67 in the radial direction. Each power supply brush 75 is accommodated in a brush holder 76 fixed to the housing 61. The power supply brush 75 is slidably contacted with each segment 73 of the commutator 67 by being biased by a biasing member 77 such as a coil spring. Further, positive and negative voltages according to rotation are applied to each power supply brush 75 from a control device (not shown).

  In the rotating electrical machine 14 configured as described above, each power supply brush 75 is in sliding contact with the segment 73 corresponding to the rotational position of the commutator 67, so that driving power is supplied to the coil 71 connected to the segment 73. The rotor 64 is rotated by a magnetic attractive force and a repulsive force generated between the magnetic field formed by energizing the coil 71 and the magnetic flux of the permanent magnet 62.

  In the tip surface 78 of the teeth 69 of the rotor 64 of the present embodiment facing the stator 63, fine concave portions are formed by pulse laser processing based on the measurement results such as the roundness of the rotor core 66, as in the first embodiment. By being formed, the magnetic resistance based on the air gap between the stator 63 and the rotor 64 is made uniform, and the cogging torque is reduced.

As described above, according to the present embodiment, the same operational effects as those of the first embodiment can be obtained.
In addition, each said embodiment can also be implemented in the following aspects which changed this suitably.

  In the first embodiment, the roundness and cylindricity of the stator core 26 are measured by the shape measuring device 51, and the teeth 25 that form the fine recesses 42 are selected based on the measurement results. However, the present invention is not limited to this. The teeth 25 may be selected by other methods. For example, as in Patent Document 2, the rotor 23 may be assembled inside the stator 22 to measure the cogging torque, and the teeth 25 that form the fine recesses 42 may be selected based on the measurement result. Similarly, in the second embodiment, a tooth for forming the fine recess 42 may be selected based on the measurement result of the cogging torque or the like.

  In the first embodiment, the stator core 26 in which the plurality of split cores 27 are arranged in an annular shape is used. However, the present invention is not limited thereto, and the stator core 26 that is not divided for each tooth 25 or the cylindrical portion 24 is used. A stator core in which each tooth 25 is divided may be used.

  In each of the above embodiments, the fine concave portion 42 is formed by scanning so that the irradiation position P of the pulse laser light L draws a circle having a gradually increasing radius. However, the irradiation position of the pulse laser is scanned in another manner. Thus, the fine recess 42 may be formed.

In each of the above embodiments, the fine recesses 42 are formed by pulse laser processing. However, the present invention is not limited thereto, and may be formed by, for example, cutting.
In each of the above embodiments, the shape of the fine recess 42 is not limited to a round hole shape, and can be appropriately changed, for example, a triangular shape or a groove shape.

In each of the above embodiments, the pulse laser beam L may be a pulse laser beam other than the nanosecond pulse laser beam, such as a femtosecond pulse laser beam.
In each of the above embodiments, the present invention is applied to the inner rotor type rotating electrical machine in which the rotors 23 and 64 are disposed on the radially inner side of the stators 22 and 63. You may apply to the outer rotor type rotary electric machine by which the rotors 23 and 64 are arrange | positioned on the outer side. Further, the present invention is not limited to a rotating electrical machine that uses a permanent magnet as a field, and may be applied to a rotating electrical machine that uses an electromagnet as a field. In short, the present invention is applicable to any rotating electrical machine having teeth around which a coil is wound. Needless to say, the rotating electrical machine 14 may be used for purposes other than the drive source of the EPS 1.

Next, technical ideas that can be understood from the above embodiments and other examples will be described below together with their effects.
(A) The pulsed laser beam is a nanosecond pulsed laser. According to the said structure, a fine recessed part can be formed in short laser irradiation time, and the influence of the heat | fever given to teeth can be suppressed.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 14 ... Rotary electric machine, 22, 63 ... Stator, 23, 64 ... Rotor, 24, 68 ... Cylindrical part, 25, 25x, 69 ... Teeth, 26 ... Stator core, 27 ... Split core , 29, 71 ... coil, 41, 78 ... tip surface, 42 ... fine recess, 51 ... shape measuring device, 53 ... pulse laser processing device, 66 ... rotor core, L ... pulse laser beam, P ... irradiation position.

Claims (4)

A rotating electrical machine comprising: a stator; and a rotor facing the stator in a radial direction, wherein at least one of the stator and the rotor is provided with a plurality of teeth extending in a radial direction and wound with a coil. In the manufacturing method,
A selection step of selecting at least one tooth to be processed to reduce cogging torque from the plurality of teeth;
A processing step of forming a plurality of fine recesses on the tip surface of the teeth selected in the selection step so that a magnetic resistance based on an air gap between the stator and the rotor is made uniform in the circumferential direction. A method of manufacturing a rotating electrical machine. In the manufacturing method of the rotary electric machine according to claim 1,
A method of manufacturing a rotating electrical machine, wherein the fine recess is formed by irradiating a pulse laser beam. In the manufacturing method of the rotary electric machine according to claim 2,
A method of manufacturing a rotating electrical machine, wherein the fine recesses are formed by scanning the pulse laser beam so that the irradiation position of the pulse laser beam gradually draws a circle having a larger radius. In a rotating electrical machine comprising a stator and a rotor facing the stator in a radial direction, wherein at least one of the stator and the rotor is provided with a plurality of teeth extending in a radial direction and wound with a coil.
A plurality of fine recesses are formed on at least one tip surface of each of the teeth so that a magnetic resistance based on an air gap between the stator and the rotor is made uniform in the circumferential direction. Rotating electric machine.