JP2004015967A - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric motor which surely suppresses torque as the whole motor. <P>SOLUTION: A motor stator 3 is equipped with a plurality of teeth 32 which are projected radially inward in radial direction from its periphery so as to oppose to a rotor 10 where a plurality of magnets 1 are arranged at its periphery and on which coils 5 are wound. The tips 321 of the above teeth 32 are made into such form that the waveform of torque patterns generated at the tips 321 of adjacent teeth 32 varies, and the tips 321 of the above adjacent teeth 32 are constituted of projections different in quantity of circumferential protrusion. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, a torque is generated by an attractive force and a repulsive force of a magnet and a plurality of teeth formed to project radially in the radial direction so as to face the magnet and around which a coil is wound, thereby rotating the rotor. More particularly, the present invention relates to a technique for reducing pulsation of torque generated by an electric motor.
[0002]
[Prior art]
As shown in FIGS. 12 and 13, the stator of the conventional electric motor has a structure in which a plurality of magnets M are arranged radially inward from the outer periphery so as to face a rotor R having a plurality of magnets M arranged at equal intervals. In a motor stator provided with a plurality of teeth portions T formed so as to project radially at equal intervals and wound with coils, the tips of adjacent teeth portions T have the same width projecting portions P having the same amount of circumferential projection. Was formed.
[0003]
As shown in FIG. 14, a conventional permanent magnet type electric motor (JP-A-10-243621) includes a permanent magnet field having P permanent magnet magnetic poles MK arranged at equal intervals over the entire circumference, Permanent magnet type electric motor including M salient poles PP arranged at equal intervals around the circumference and an armature A having armature windings wound around the salient poles PP and connected in three phases. Wherein the relationship between the number of poles p of the permanent magnet magnetic poles MK and the number of poles m of the salient poles PP is made constant, and the position is mechanically different from the center of the motor by nearly 180 degrees (symmetrical position). By selecting the armature winding wound around the salient pole PP in the same phase, the influence of the unbalance of the air gap is small, and the mounting error in the electric angle of the position detecting element of the permanent magnet pole MK is reduced to reduce the torque ripple. Suppress and provide low vibration motor It was the.
[0004]
[Problems to be solved by the invention]
The above-described conventional electric motor is configured so that the torque waveform generated at each tooth has a predetermined phase difference, and these are added to suppress torque pulsation (ripple). It could not be reduced to a level where there was no problem in practical use.
[0005]
Further, in the conventional permanent magnet type electric motor described above, the relationship between the number of poles p of the permanent magnet magnetic pole MK and the number of poles m of the salient magnetic pole PP is fixed, and the position is mechanically different from the center of the motor by nearly 180 degrees. By selecting the armature winding wound around the (symmetrical position) salient magnetic pole PP in the same phase, the influence of air gap unbalance is reduced, and the mounting error of the permanent magnet magnetic pole MK in the electrical angle of the position detecting element is reduced. Although the torque ripple is reduced to reduce the torque ripple, the salient pole PP does not suppress the amplitude between both peaks, and a torque waveform having a large amplitude between both peaks is generated. There was a problem that the ripple was large.
[0006]
Therefore, the present inventor has proposed a rotor in which a plurality of magnets are arranged on an outer peripheral portion, and a plurality of coils in which a coil is wound radially inwardly from the outer peripheral portion so as to face the magnets so as to face the magnets. In an electric motor formed by combining a stator having a tooth portion, a tip of the tooth portion generates a torque pattern having a waveform different from a waveform of a torque pattern generated at a tip of an adjacent tooth portion. Focusing on the technical idea of the present invention that complements the torque fluctuations that occur and suppresses the pulsation of the resultant torque generated in the rotor, as a result of further research and development, the torque ripple is reliably suppressed as a whole motor. The present invention has been achieved which achieves the above object.
That is, by changing the shape of the tip of the tooth portion, the waveform of the torque generated by each tooth portion changes, but by adjusting this shape, the variation in the torque generated by each tooth is complemented mutually, The pulsation of the combined torque (output torque of the electric motor) generated in the rotor, which is the sum of these torques, is suppressed.
[0007]
This principle will be described in more detail with reference to FIG. 5, which conceptually shows how the torque generated in each tooth portion is added to become a combined torque generated in the rotor. As described in the above prior art, the number of poles of the teeth and the number of poles of the permanent magnet are not the same, and as shown in (a), (b), and (c) of FIG. If the generated torque waveforms have a predetermined phase difference, they are added to each other, so that torque pulsation can be suppressed to some extent as shown in (d) of FIG.
However, the waveform of the torque generated by each tooth has the same shape, and there is a limit to the effect of suppressing the torque pulsation even if the phases are shifted and combined. (If the phase shift is 120 ° and the waveform of the torque generated by each tooth is a perfect sine wave, the torque pulsation is theoretically eliminated, but the torque waveform does not actually become a perfect sine wave. .)
[0008]
Therefore, in the present invention, by changing the shape of the teeth in one stator, torque having a different waveform is generated for each tooth as shown in (a), (b), and (c) of FIG. Are combined to compensate for torque fluctuations, and as shown in FIG. 11D, an output torque with less pulsation can be obtained. This idea can be similarly applied to an electric motor in which the rotor is provided with teeth and the stator is provided with magnets. Note that the horizontal axis of each graph in FIG. 5 indicates time or rotor angle.
[0009]
[Means for Solving the Problems]
The electric motor according to the present invention (first invention according to claim 1)
A stator having a rotor having a plurality of magnets disposed on an outer peripheral portion thereof, and a plurality of teeth portions formed to project radially inward from the outer peripheral portion to face the magnets and to be wound with coils; In an electric motor comprising a combination of
The tip of the tooth portion is formed in a shape that generates a torque pattern having a waveform different from the waveform of the torque pattern generated at the tip of an adjacent tooth portion.
Things.
[0010]
The electric motor according to the present invention (the second invention according to claim 2)
In the first invention,
The protrusion amounts of the circumferential protrusions at the tips of the adjacent teeth are different.
Things.
[0011]
The electric motor of the present invention (third invention according to claim 3) is
In the second invention,
Protrusions with small protrusion amounts in the circumferential direction of the tips of the adjacent tooth portions and protrusions with large protrusion amounts are arranged alternately.
Things.
[0012]
The electric motor of the present invention (the fourth invention according to claim 4) is
In the third invention,
The protrusion with the small protrusion amount is set smaller than the width of the magnet provided on the outer peripheral portion of the rotor, and the protrusion with the large protrusion amount is set larger than the width of the magnet.
Things.
[0013]
The electric motor according to the present invention (fifth invention according to claim 5)
In the fourth invention,
The protrusions having the same width as the width of the teeth portion having almost no protrusion amount in the circumferential direction of the tip of the adjacent tooth portion and the protrusion portions having a constant protrusion amount are alternately arranged.
Things.
[0014]
The electric motor according to the present invention (the sixth invention according to claim 6)
In the first invention,
Both sides of the opposing portion opposing the rotor in the circumferentially protruding protruding portion of the tip of the adjacent tooth portion are formed in a chamfered shape away from the outer peripheral surface of the rotor.
Things.
[0015]
The electric motor according to the present invention (the seventh invention according to claim 7)
A stator having a rotor having a plurality of magnets disposed on an outer peripheral portion thereof, and a plurality of teeth portions formed to project radially inward from the outer peripheral portion to face the magnets and to be wound with coils; In an electric motor comprising a combination of
The arrangement phases of the magnets arranged on the outer periphery of the rotor are different.
Things.
[0016]
The electric motor according to the present invention (the eighth invention according to claim 8)
In the seventh invention,
Adjacent magnets disposed on the outer periphery of the rotor have different circumferential widths of the rotor.
[0017]
The electric motor of the present invention (a ninth invention according to claim 9) is
In the seventh invention,
The circumferential distance of the rotor is different between adjacent magnets disposed on the outer periphery of the rotor.
Things.
[0018]
The electric motor according to the present invention (the tenth invention according to claim 10)
A stator having a plurality of magnets disposed on an inner peripheral portion thereof, and a rotor having a plurality of teeth portions formed with radially outwardly projecting radially to face the magnets and wound with coils. In an electric motor comprising a combination,
The tips of the teeth are formed in a shape that generates a torque pattern having a waveform different from the waveform of the torque pattern generated at the tips of the adjacent teeth, and the torque patterns generated in each of the teeth complement each other to form the rotor. It is configured to suppress the pulsation of the synthetic torque generated in
Things.
[0019]
The electric motor of the present invention (the eleventh invention according to claim 11) is
A stator having a plurality of magnets disposed on an inner peripheral portion thereof, and a rotor having a plurality of teeth portions formed with radially outwardly projecting radially to face the magnets and wound with coils. In an electric motor comprising a combination,
The arrangement phases of the magnets arranged on the inner peripheral portion of the stator are different.
Things.
[0020]
Function and Effect of the Invention
The electric motor according to the first aspect of the present invention has a rotor in which a plurality of magnets are disposed on an outer peripheral portion, and a coil formed radially inward from the outer peripheral portion so as to face the magnet so as to face the magnet. In an electric motor formed by combining a stator having a plurality of wound teeth portions, a tip of the tooth portion is formed in a shape such that a waveform of a torque pattern generated at a tip of an adjacent tooth portion is different. Therefore, the fluctuations in the torque generated by each of the teeth are complemented with each other, so that the pulsation of the resultant torque generated in the rotor can be suppressed, and the vibration and noise of the motor can be reduced.
[0021]
In the electric motor of the second invention having the above configuration, in the first invention, since the protrusion amounts of the circumferential projections at the tips of the adjacent teeth are different, the wide tips of the teeth have A torque pattern in which the amplitude between the two peaks is suppressed is generated, and a torque pattern in which the amplitude between the two peaks is relatively large is generated at the narrow end of the teeth portion so that the torque ripple is generated as a whole motor. This has the effect of reliably suppressing.
[0022]
The electric motor according to a third aspect of the present invention is the electric motor according to the second aspect, wherein the protrusions having a small protrusion amount in the circumferential direction of the tip of the adjacent tooth portion and the protrusion portions having a large protrusion amount are alternately arranged. Therefore, a torque pattern in which the amplitude between both peaks is suppressed is generated at the tip where the amount of protrusion of the teeth portion is large, and the amplitude between both peaks is generated at the tip where the amount of protrusion of the teeth portion is small. By generating a relatively large torque pattern, there is an effect that torque ripple is reliably suppressed in the entire motor.
[0023]
In the electric motor according to a fourth aspect of the present invention, in the third aspect, the projecting portion having a small projecting amount is smaller than a width of a magnet arranged on an outer peripheral portion of the rotor, and the projecting portion having a large projecting amount is Since the width of the magnet is set to be larger than the width of the teeth, the tip of the tooth portion set to be larger than the width of the magnet has a large protrusion amount, while generating a torque pattern in which the amplitude between both peaks is suppressed, At the tip where the amount of protrusion of the teeth portion set smaller than the width of the magnet is small, a torque pattern in which the amplitude between both peaks is relatively large is generated, so that the torque ripple is reliably suppressed as a whole motor. To play.
[0024]
The electric motor according to a fifth aspect of the present invention is the electric motor according to the fourth aspect, wherein the protrusion of the tip of the adjacent tooth has substantially the same width as the width of the tooth having almost no protrusion in the circumferential direction. Since the protrusions and the protrusions are alternately arranged, a torque pattern in which the amplitude between both peaks is suppressed is generated at the tip of the fixed protrusion amount of the teeth portion, and the protrusion amount of the teeth portion is almost By generating a torque pattern having a relatively large amplitude between the two peaks at the leading end that does not have such an effect, an effect of reliably suppressing torque ripple in the entire motor is achieved.
[0025]
The electric motor according to a sixth aspect of the present invention is the electric motor according to the first aspect, wherein both sides of the opposing portion facing the rotor in the circumferentially protruding tip of the tip of the adjacent tooth portion are formed on the outer periphery of the rotor. Since the torque portion is formed in a chamfered shape that is farther from the surface, a torque pattern in which the amplitude between both peaks is relatively suppressed is generated at the tip of the tooth portion formed in the chamfered shape, so that the torque ripple is reduced as a whole motor. Is achieved.
[0026]
The electric motor according to the seventh aspect of the present invention is configured such that a rotor having a plurality of magnets disposed on an outer peripheral portion thereof and a coil radially inwardly protruding from the outer peripheral portion to face the magnets are formed. In an electric motor formed by combining a stator having a plurality of wound teeth portions, the arrangement phase of magnets arranged on the outer peripheral portion of the rotor is different. By generating a torque pattern in which the amplitude of the motor is relatively suppressed, there is an effect that the torque ripple is reliably suppressed in the motor as a whole.
[0027]
An electric motor according to an eighth aspect of the present invention is the electric motor according to the seventh aspect, wherein adjacent magnets disposed on an outer peripheral portion of the rotor have different circumferential widths of rotors. By generating a torque pattern in which the amplitude between the two peaks is relatively suppressed, an effect of reliably suppressing torque ripple in the motor as a whole is obtained.
[0028]
The electric motor according to a ninth aspect of the present invention is the electric motor according to the seventh aspect, wherein a distance between adjacent magnets disposed on an outer peripheral portion of the rotor in the circumferential direction of the rotor is different, so that In addition, by generating a torque pattern in which the amplitude between the two peaks is relatively suppressed, there is an effect that the torque ripple is reliably suppressed in the entire motor.
[0029]
An electric motor according to a tenth aspect of the present invention, comprising: a stator having a plurality of magnets disposed on an inner peripheral portion thereof; and a radially outwardly projecting coil formed opposite to the magnet and having a coil wound thereon. An electric motor formed by combining a rotor having a plurality of tooth portions, wherein the tip of the tooth portion has a shape that generates a torque pattern having a waveform different from the waveform of a torque pattern generated at the tip of an adjacent tooth portion. As a result, the fluctuations in the torque generated by each of the teeth are complemented with each other, so that the pulsation of the resultant torque generated in the rotor can be suppressed, and the vibration and noise of the motor can be reduced.
[0030]
An electric motor according to an eleventh aspect of the present invention having the above-mentioned structure, comprises a stator having a plurality of magnets disposed on an inner peripheral portion thereof, and a coil formed by projecting radially outward to face the magnets. In the electric motor which is combined with a rotor having a plurality of teeth portions, the arrangement pattern of the magnets arranged on the inner peripheral portion of the stator is different, so that the torque pattern generated in each magnet is different, By complementing each other, there is an effect that torque ripple can be suppressed as a whole of the motor and vibration and noise of the motor can be reduced.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
(1st Embodiment)
As shown in FIGS. 1 to 4, the electric motor according to the first embodiment moves radially inward from an outer peripheral portion 31 so as to face a rotor 10 having a plurality of magnets 1 disposed on the outer peripheral portion. In the motor stator 3 provided with a plurality of teeth portions 32 which are formed so as to project radially and around which the coil 5 is wound, the tip 321 of the tooth portion 32 has a waveform of a torque pattern generated at the tip 321 of the adjacent tooth portion 32. It is formed in a different shape, and the tip 321 of the adjacent tooth portion 32 is constituted by a projecting portion having a different circumferential projecting amount.
[0033]
The electric motor 20 according to the first embodiment is applied to, for example, an electric power steering device for an automobile.
As shown in FIGS. 3 and 4, the electric power steering device 40 includes a rack housing 11, a tube yoke housing 13 coaxially attached to an end of the rack housing 11, and a tube yoke housing 13. And an end housing 14 coaxially attached to the end.
[0034]
Each of these three housings is formed in a hollow and substantially cylindrical shape, and a rack shaft 12 is inserted therein. A hollow iron motor shaft as the rotor 10 is rotatably inserted into the tube yoke housing 13 via bearings 17 and 30.
[0035]
A ball screw nut 16 is fixed to the motor shaft 10, and the rack shaft 12 is coupled via the ball screw nut 16 so as to be movable in the axial direction. Tie rods 19 connected to the steered wheels via ball joints 18 are connected to both ends of the rack shaft 12, respectively.
[0036]
As shown in FIG. 3, a motor 20 is mounted inside the tube yoke housing 13, and the motor 20 has a motor shaft 10 as a rotation shaft inserted therethrough.
[0037]
The motor 20 includes an armature core as the motor stator 3 fixed to the inner peripheral surface of the tube yoke housing 13 and a ring magnet as the magnet 1 bonded to the outer peripheral surface of the motor shaft 10. That is, the motor shaft 10 forms a magnetic path.
[0038]
As shown in FIGS. 1 and 2, the motor stator 3 as an armature core is formed by laminating a large number of iron cores, and has an outer peripheral portion 31 facing the tube yoke housing 13 and a radially inner portion from the outer peripheral portion 31. And a plurality of teeth portions 32 formed so as to protrude radially in the direction toward which the coil 5 as the armature winding is wound.
[0039]
In the first embodiment, at the tip 321 of the adjacent teeth 32, the protrusions 3211 having a small protrusion amount in the circumferential direction of the motor and the protrusion portions 3212 having a large protrusion amount are alternately arranged. It is.
[0040]
That is, specifically, at the tip 321 of the adjacent tooth portion 32, a protrusion 3211 having a width equal to the width of the tooth portion 32 and a protrusion 3212 having a constant protrusion amount are provided. Are alternately arranged.
[0041]
As shown in FIG. 2, the circumferential width of the protrusion 3211 having a small protrusion amount is smaller than the circumferential width (for example, 7.0 mm) of the magnet 1 bonded to the outer peripheral surface of the motor shaft 10 (for example, 7.0 mm). (For example, 4.4 mm), and the circumferential width of the protrusion 3212 having a large protrusion amount is set to be larger (for example, 7.9 mm) than the circumferential width of the magnet 1.
[0042]
Further, the width of the magnet 1 bonded to the outer peripheral surface of the motor shaft 10, the protrusion 3211 having a small protrusion amount, and the protrusion 3212 having a large protrusion amount in the circumferential direction of the motor are bonded to the outer circumferential surface of the motor shaft 10. The magnet 1 is set so as to face either the protrusion 3211 having a small protrusion amount or the protrusion 3212 having a large protrusion amount.
[0043]
In the electric motor according to the first embodiment having the above-described configuration, the protrusions 3211 having a small protrusion amount in the circumferential direction of the tip 321 of the adjacent tooth portion 32 and the protrusion portions 3212 having a large protrusion amount are alternately arranged. ing. These projections have different waveforms between the torque generated at the tip 3212 having a large projection and the torque generated at the tip 3211 having a small projection, and complement each other to reduce torque ripple as a whole motor. It has been adjusted to allow. Thereby, there is an effect that the torque ripple is surely suppressed in the entire motor.
[0044]
Further, in the electric motor of the first embodiment, since the protrusion amount of the circumferential protrusion of the tip 321 of the adjacent tooth portion 32 is different, the wide tip 3212 of the tooth portion has A torque pattern with suppressed amplitude is generated, and a torque pattern having a relatively large amplitude between both peaks is generated at the narrow tip 3211 of the teeth portion, thereby reliably suppressing torque ripple in the entire motor. It has the effect of doing.
[0045]
In the first embodiment, as is clear from FIGS. 1 and 2, only the amount of protrusion of the distal end 321 of the tooth portion 32 in the circumferential direction is different, and portions other than the distal end 321 of each tooth portion 32 are different. Since the teeth with a small protrusion amount have a higher magnetic flux density at the tip end of the teeth than the teeth with a large protrusion amount, the force received in the radial direction fluctuates greatly, so the same shape that can suppress the occurrence of vibration during motor rotation And the same size, so that the entire stator and the motor have uniform strength and rigidity, so that the problem caused by uneven strength and rigidity of the entire stator and motor is solved. It is.
[0046]
Further, in the electric motor according to the first embodiment, the protruding portions 3211 having a small protruding amount in the circumferential direction of the tips 321 of the adjacent tooth portions 32 and the protruding portions 3212 having a large protruding amount are alternately arranged. In addition, the vibration of the motor generated by the radial force applied to the rotor and the stator can be suppressed.
That is, the teeth having a small protrusion amount have a higher magnetic flux density at the tooth tip portion than the teeth having a large protrusion amount, so that the force received in the radial direction fluctuates greatly. As a result, vibration during rotation of the motor is likely to occur, but by arranging these teeth alternately, the arrangement of the teeth becomes substantially symmetric with respect to the axis, and the force received in the radial direction can be offset. Since the forces received in the directions can be distributed in a well-balanced manner, the vibration can be minimized.
[0047]
The electric motor according to the first embodiment includes a protrusion 3211 having a width equal to the width of a tooth portion having almost no protrusion amount in the circumferential direction of the tip 321 of the adjacent tooth portion 32 and a protrusion portion 3212 having a predetermined protrusion amount. Are alternately arranged, so that a wide torque pattern in which the amplitude between both peaks of the torque waveform is suppressed is generated at the tip 3212 of the tooth portion having a constant protrusion amount, and the tooth portion has a protrusion. By generating a narrow torque pattern with a relatively large amplitude between both peaks of the torque waveform at the tip 3211 having almost no amount, the torque ripple is effectively suppressed as a whole motor.
[0048]
FIG. 6 shows a waveform of the output torque as an evaluation result of the electric motor of the first embodiment. FIG. 6B shows an output torque waveform of the conventional electric motor, and FIG. 6A shows an output torque waveform of the electric motor of the first embodiment. As can be seen from the experimental results, torque pulsation (difference between the maximum value and the minimum value) is suppressed to about half.
[0049]
As shown in the experimental results, the absolute value of the torque is smaller than that of the conventional one, but this is not a serious problem. The results of this experiment were based on the same size of the stator, rotor, permanent magnet, and supply current. Increasing the absolute value of the torque requires strengthening the permanent magnet and increasing the current flowing through the stator windings. Is possible more easily. Particularly in the case of an electric motor for power assist of an electric power steering device for an automobile, if the torque pulsates, the driver's steering feeling will be uncomfortable, so it is extremely important to suppress the torque pulsation. Become.
[0050]
(2nd Embodiment)
The electric motor according to the second embodiment is different from the first embodiment in that the distance between the front end 321 of the tooth portion 32 and the magnet 1 disposed on the outer peripheral portion of the rotor 10 differs depending on the position as shown in FIG. This is a difference from the embodiment, and the following description will focus on the difference.
[0051]
That is, the electric motor of the second embodiment radially projects from the outer peripheral portion 31 inward in the radial direction so as to face a rotor having a plurality of magnets 1 disposed on the outer peripheral portion as shown in FIG. In the motor stator 3 including a plurality of teeth 32 formed and wound with coils, both sides of a facing part 321T of the tip part 321 of a part of the teeth 32 protruding in the circumferential direction facing the rotor. Are formed in a chamfered shape that is farther from the outer peripheral surface of the rotor 10. Note that the broken line in FIG. 7 is provided to clearly show the difference in the shape of the stator.
[0052]
The electric motor according to the second embodiment having the above-described configuration is configured such that both sides of the facing portion 321 </ b> T of the protruding portion protruding in the circumferential direction of the tip 321 of the teeth portion 32 are opposed to the outer peripheral surface of the rotor 10. Since both sides of the facing portion 321T are farther from the outer peripheral surface of the rotor 10, the peak of the torque pattern waveform generated at the tip 321 of the teeth portion 32 is lowered and smoothed. Things.
[0053]
In the electric motor according to the second embodiment having the above-described operation, since the teeth having different shapes are mixed, the waveform of the generated torque is different for each tooth, and these are mutually complemented, and the torque ripple is surely reduced as the whole motor. This has the effect of suppressing it. The shape of the teeth is adjusted to an optimum shape by performing a magnetic path analysis or the like by computer simulation or the like.
[0054]
(Third embodiment)
The electric motor of the third embodiment is different from the first embodiment in that the arrangement phases of a plurality of magnets 1 arranged on the outer peripheral portion of the rotor 10 are different as shown in FIG. Yes, the differences will be mainly described below.
[0055]
That is, similarly to the first embodiment, the electric motor of the third embodiment radially inward from the outer peripheral portion so as to face the rotor 10 having the plurality of magnets 1 disposed on the outer peripheral portion. As shown in FIG. 8, in the electric motor having a plurality of teeth formed so as to be protruded and wound with coils, the circumferential width of the adjacent magnets 1 disposed on the outer periphery of the rotor 10 as shown in FIG. Are different.
[0056]
In the electric motor according to the third embodiment, since the arrangement phase of the magnets 1 arranged on the outer peripheral portion of the rotor 10 is different, the amplitude between the two peaks is relatively suppressed at the tip 321 of the teeth portion 32 and the pulse By generating a wide torque pattern, there is an effect that the torque ripple is reliably suppressed in the entire motor.
[0057]
In the electric motor according to the third embodiment, the width of the adjacent magnets 1 disposed on the outer peripheral portion of the rotor 10 in the circumferential direction of the rotor is different. Is relatively suppressed and a torque pattern with a wide pulse width is generated, whereby the effect of reliably suppressing the torque ripple in the entire motor is achieved.
[0058]
(Fourth embodiment)
The electric motor according to the fourth embodiment is different from the third embodiment in that, as shown in FIG. 9, the circumferential distance of the rotor between adjacent magnets 1 arranged on the outer periphery of the rotor 10 is different. This is a difference from the embodiment, and the following description will focus on the difference.
[0059]
As shown in FIG. 9, the electric motor according to the fourth embodiment has a different rotor circumferential distance between adjacent magnets 1 disposed on the outer periphery of the rotor 10. Since the left and right intervals in the circumferential direction are different, the amplitude of the peak between the two peaks is relatively suppressed and a torque pattern with a wide pulse width is generated at the tip of the tooth portion facing the rotor 10 so that the torque of the entire motor is reduced. This has the effect of reliably suppressing ripple.
[0060]
(Fifth embodiment)
As described above, the basic technical idea of the present invention applies not only to an electric motor having a magnet in a rotor and also having teeth in a stator, but also to an electric motor having a tooth in a rotor and a magnet in a stator. Applicable. The fifth embodiment and a sixth embodiment described below relate to an electric motor having a rotor with teeth and a stator with magnets.
[0061]
In the electric motor according to the fifth embodiment, as shown in FIG. 10, a plurality of magnets 51 are disposed on an inner peripheral portion of a stator 50, and a rotor 52 is disposed radially outward so as to face the magnets 51. The difference from the first embodiment is that teeth 531 and 532 protrude radially toward the first embodiment, and the following description will focus on the differences.
[0062]
The teeth of the electric motor shown in FIG. 10 include a tooth 531 in which the width of the tooth tip 5311 is formed to be narrower than the width of the magnet 51, and a tooth in which the width of the tooth tip 5312 is wider than the width of the magnet 51. The formed teeth 532 are arranged alternately. The width of each tooth is optimally adjusted so that the torque generated by each tooth complements each other to output torque with less pulsation as a whole motor. Further, as shown in FIG. 7, both ends of the tooth may be formed so as to be away from the magnet. Thereby, the same operation and effect as those of the first embodiment and the second embodiment can be obtained.
[0063]
(Sixth embodiment)
In the electric motor according to the sixth embodiment, as shown in FIG. 11, a plurality of magnets 511 and 512 having different widths are disposed on the inner peripheral portion of the stator 50, and the rotor 52 faces the magnets 511 and 512. The difference between the fifth embodiment and the fifth embodiment is that the teeth 53 protrude radially outward as described above, and the following description will focus on the differences.
[0064]
The magnet of the electric motor shown in FIG. 11 is a combination of a magnet 512 formed with a width smaller than the width of the teeth 53 and a magnet 511 formed with a width larger than the width of the teeth 53. The width and arrangement of the respective magnets are optimally adjusted so that the torque generated by the respective magnets complements each other to output a torque with less pulsation as a whole motor. Thereby, the same operation and effect as the third embodiment and the fourth embodiment can be obtained.
[0065]
The above-described embodiment has been described by way of example, and the present invention is not limited to the embodiment. It will be recognized by those skilled in the art from the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without violating the technical idea of the present invention.
[0066]
In the above-described first embodiment, an example has been described in which portions other than the tip 321 of each of the teeth portions 32 have the same shape and the same size, but the present invention is not limited thereto, and the protrusion is not limited thereto. The smaller the amount of teeth, the higher the magnetic flux density at the tip of the teeth compared to the larger amount of teeth, so that the force received in the radial direction fluctuates greatly. It is possible to adopt an embodiment in which the width of the other portion of the tooth portion 32 having a small diameter is increased to have sufficient strength.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an electric motor according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional view illustrating a main part of the electric motor according to the first embodiment.
FIG. 3 is a partially cutaway sectional view showing an electric power steering apparatus to which the motor of the first embodiment is applied.
FIG. 4 is a partially enlarged sectional view showing a motor section of the electric power steering apparatus to which the first embodiment is applied.
FIG. 5 is a diagram showing a torque pattern and a torque ripple at a tip of each tooth portion of the electric motor according to the first embodiment and a conventional electric motor, respectively.
FIG. 6 is a diagram showing a relationship between a rotation angle and a torque in the first embodiment and a conventional electric motor.
FIG. 7 is a partial sectional view showing a main part of an electric motor according to a second embodiment of the present invention.
FIG. 8 is a partial sectional view showing a main part of an electric motor according to a third embodiment of the present invention.
FIG. 9 is a partial sectional view showing a main part of an electric motor according to a fourth embodiment of the present invention.
FIG. 10 is a partial sectional view showing a main part of an electric motor according to a fifth embodiment of the present invention.
FIG. 11 is a partial sectional view showing a main part of an electric motor according to a sixth embodiment of the present invention.
FIG. 12 is a sectional view showing a conventional electric motor.
FIG. 13 is a partial sectional view showing a main part of a conventional electric motor.
FIG. 14 is a side view showing a conventional permanent magnet type electric motor.
[Explanation of symbols]
1 magnet
5 coils
10 rotor
31 Outer circumference
32 teeth section
321 tip

Claims (11)

A stator having a rotor having a plurality of magnets disposed on an outer peripheral portion thereof, and a plurality of teeth portions formed to project radially inward from the outer peripheral portion to face the magnets and to be wound with coils; In an electric motor comprising a combination of
An electric motor, wherein a tip of the tooth portion is formed in a shape that generates a torque pattern having a waveform different from a waveform of a torque pattern generated at a tip of an adjacent tooth portion. In claim 1,
An electric motor characterized in that the projecting amounts of the projecting portions in the circumferential direction at the tips of the adjacent tooth portions are different. In claim 2,
An electric motor, wherein protrusions having a small protrusion amount in the circumferential direction of the tips of the adjacent tooth portions and protrusions having a large protrusion amount are alternately arranged. In claim 3,
The electric motor, wherein the protrusion having a small protrusion amount is smaller than a width of a magnet arranged on an outer peripheral portion of the rotor, and the protrusion having a large protrusion amount is set to be larger than the width of the magnet. . In claim 4,
An electric motor characterized in that protrusions having a width equal to the width of a tooth portion having almost no protrusion amount in the circumferential direction at the tip of the adjacent tooth portion and protrusions having a fixed protrusion amount are alternately arranged. . In claim 1,
An electric motor characterized in that both sides of an opposing portion facing the rotor in a circumferentially protruding portion of the tip of the adjacent tooth portion are formed in a chamfered shape away from the outer peripheral surface of the rotor. A stator having a rotor having a plurality of magnets disposed on an outer peripheral portion thereof, and a plurality of teeth portions formed to project radially inward from the outer peripheral portion to face the magnets and to be wound with coils; In an electric motor comprising a combination of
An electric motor, wherein the arrangement phases of the magnets arranged on the outer peripheral portion of the rotor are different. In claim 7,
An electric motor according to claim 1, wherein adjacent magnets provided on an outer peripheral portion of said rotor have different circumferential widths of said rotor. In claim 7,
An electric motor, characterized in that adjacent rotors arranged on the outer periphery of the rotor have different circumferential intervals of the rotor. A stator having a plurality of magnets disposed on an inner peripheral portion thereof, and a rotor having a plurality of teeth portions formed with radially outwardly projecting radially to face the magnets and wound with coils. In the electric motor configured in combination, the tip of the tooth portion is formed in a shape that generates a torque pattern having a waveform different from the waveform of the torque pattern generated at the tip of the adjacent tooth portion, and the torque pattern generated by each of these teeth is An electric motor, wherein the electric motor is configured to complement each other to suppress pulsation of a resultant torque generated in the rotor. A stator having a plurality of magnets disposed on an inner peripheral portion thereof, and a rotor having a plurality of teeth portions formed with radially outwardly projecting radially to face the magnets and wound with coils. In an electric motor comprising a combination,
An electric motor, wherein the arrangement phases of magnets arranged on an inner peripheral portion of the stator are different.

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