JP4595249B2 - Single phase induction motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-phase induction motor, and more particularly, to a skew shape of a stator and a rotor that suppress harmonic torque.
[0002]
[Prior art]
The single-phase induction motor has a phase difference between the main winding and the auxiliary winding, a magnetomotive force difference, and the like, and forms a large harmonic magnetic field in the gap between the stator and the rotor. In addition to this, there is a harmonic magnetic field or the like due to the pulsation of slot permeance, and the harmonic magnetic field in the air gap becomes large, and a large amount of harmonic torque is included, greatly affecting the torque characteristics. In order to reduce such harmonics, it is known to twist the stator or rotor slots at an angle with respect to the axial direction to form a skew. In general, the skew is often difficult to form in the stator on which the winding is mounted, and is formed only in the cage rotor without the winding.
[0003]
Further, in order to shorten the coil end to reduce the amount of copper and simplify the forming of the winding, as described in JP-A-11-285212, one winding is provided for each tooth of the stator. A so-called concentrated winding stator that winds in a concentrated manner is employed.
[0004]
[Problems to be solved by the invention]
However, even if skew is formed in the rotor, there is a problem that if the skew angle is not an appropriate value, the torque characteristics are deteriorated or the slot harmonics of the rotor cannot be sufficiently improved. .
[0005]
Further, in the case of the concentrated winding stator, a higher harmonic magnetic field than that of the distributed winding stator is generated in the gap between the stator and the rotor. This harmonic magnetic field acts as an electromagnetic excitation force on the rotor and the stator, and has a problem of adverse effects such as vibration and noise. In particular, in induction motors used for home appliances such as a ventilation fan, vibration and noise are major problems.
[0006]
The present invention has been made to solve the above problems, and provides a single-phase induction motor that reduces electromagnetic excitation force due to harmonics by making the rotor skew and the skew of the stator appropriate shapes. For the purpose.
[0007]
[Means for Solving the Problems]
A single-phase induction motor according to the present invention includes a stator having a plurality of teeth and a plurality of slots formed between the teeth, a stator winding wound around each of the teeth,
A rotor having a squirrel-cage secondary conductor passing through the slot and rotating by magnetic flux generated from the stator, and the stator slot is skewed by a predetermined angle only at the tip of the teeth. formed Te Rutotomoni, the rotor slots slot and inclined direction of the stator is skewed differently, the sum of the skew angle of the rotor with a skew angle of the stator slot pitch angle of the stator The rotor skew angle is formed to be equal to the sum of the angle β formed by the tip width in the winding portion of the stator and the angle γ formed by the slot opening width in the stator. .
[0008]
The width of the tip of the stator teeth of the stator is formed to be narrower than the width of the root.
[0009]
Further, the skew of the stator slot has a V shape that bends near the center in the axial direction, and the skew of the rotor slot has a V shape that bends in the direction different from the skew of the stator near the center in the axial direction. Is.
[0010]
Deleted by correction.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
An embodiment of the present invention will be described with reference to FIGS. 1 is a front view of a stator of a single-phase induction motor, FIG. 2 is a front view of a stator and a rotor of a single-phase induction motor, FIG. 3 is an exploded perspective view of the stator, and FIG. 4 is an exploded perspective view of the rotor. FIG. 5 and FIG. 5 are partial development views of the stator facing surface of the rotor.
[0012]
As shown in FIGS. 1 and 2, the single-phase induction motor includes a stator 1 and a rotor 20, and the stator 1 includes a stator core 3 formed by laminating a plurality of silicon steel plates, The stator core 3 is composed of a main winding 6a and an auxiliary winding 6b housed in a slot 11 of the stator core 3. The stator core 3 is formed by an outer diameter portion 7 formed in a cylindrical shape and eight teeth 9 extending from the inner peripheral side of the outer diameter portion 7 toward the axial center. That is, eight stator slots 11 are formed between adjacent teeth 9, and four main windings 6 a wound in a ring shape and four auxiliary coils are formed in the stator slots 11. The windings 6b are alternately accommodated to form a so-called concentrated winding stator.
[0013]
The rotor 20 is a cage type, formed by laminating a plurality of silicon steel plates, and a rotor core 24 in which 14 rotor slots 22 are arranged on the outer peripheral portion, and a conductive portion passing through the rotor slot 22. 26a and a secondary conductor 26 composed of an end ring 26b disposed on both end faces of the rotor core 24. A hole 30 is provided in the center of the rotor core 24 to which a shaft is attached.
[0014]
As shown in FIG. 3, the stator 1 is formed with a stator skew 3a having a skew angle θs [degrees] at a slot pitch α [degrees]. Here, the skew angle θs is defined by the line segment connecting the center point O on the upper surface of the stator 1 and the upper end S of the opening of the stator slot 11, and the center point O on the upper surface of the stator 1 and the stator slot 11. This is an angle formed by a line segment connecting the lower end of the opening to the point S ′ projected onto the upper surface of the stator 1, and the slot pitch α is an angle viewed from the center point O of the stator 1.
[0015]
Further, the stator skew 3 a is formed only at the tip of the tooth 9. That is, each of the laminated silicon steel sheets has the same shape in the portion around which the winding of the teeth 9 is wound, and the shape around the opening of the stator slot 11 is different. By stacking straight so as not to be inclined, the opening of the stator slot 11 is gradually shifted in the circumferential direction, and only the tip of the tooth 9 is skewed by a predetermined angle as a whole.
[0016]
As shown in FIG. 4, a rotor skew 22 a having a skew angle θr [degree] is formed on the surface of the rotor 20 so as to cross the stator skew 3 a with a different inclination direction. This skew angle θr is defined by the line segment connecting the center point O ′ on the upper surface of the rotor 20 and the upper end R of the opening of the rotor slot 22 and the center point O ′ on the upper surface of the rotor 20 and the rotor slot 22. This is an angle formed by a line segment connecting a point R ′ projected from the lower end of the opening onto the upper surface of the rotor 20.
[0017]
Next, the reason why the skew is formed in both the stator 1 and the rotor 20 will be described. The harmonic torque is generated by the interaction of the magnetic field generated in the gap between the stator 1 and the rotor 20 by the harmonic and magnetomotive harmonic of the stator slot 11 and the eddy current generated in the secondary conductor 26 due to these harmonics. ing. For this reason, in order to suppress the harmonic torque due to the harmonics of the stator slot 11, it is preferable to form a skew 22a in the rotor 20 near the stator slot pitch α. In particular, in the case of a concentrated winding stator, a harmonic magnetic field having a smaller spatial harmonic order is larger than that of a distributed winding stator, so that it is necessary to increase the skew angle.
[0018]
However, it is often difficult to form the skew 22a up to the vicinity of the stator slot pitch α only by the rotor skew 22a. Even if it can be formed, the angle of the rotor skew 22a increases as shown in FIG. The slot opening width L of the rotor 20 is equivalently narrowed as La and the leakage magnetic flux is increased, or the secondary conductor is equivalently lengthened and the secondary resistance is increased to increase the loss. And the problem that it is difficult to die-cast aluminum as a secondary conductor. In particular, in a small single-layer induction motor having a diameter of about 60 mm used for, for example, a ventilation fan, the slot opening width L of the rotor 20 is narrow. Therefore, when the skew angle is increased, the end of the laminated steel sheet facing the slot opening is reduced. There is a high risk of contact, and there is a limit to the skew angle that can be formed.
[0019]
Therefore, a skew is also formed in the stator 1 so that the angle of the rotor skew 22a can be reduced. Also, if the inclination direction of the stator skew is the same as the rotor skew, the rotor skew angle may have to be increased to obtain the required skew angle. Formed differently.
[0020]
On the other hand, when the skew is formed in the stator 1, in general, the laminated steel sheets having the same shape are stacked by being rotated little by little by the skew angle at the time of stacking to form the skew. There is a problem that the wire length becomes long and the copper loss increases or high-density winding becomes difficult. Therefore, by forming the stator skew 3a only at the tip portion of the tooth 9 as described above, the winding length is shortened to reduce the copper loss, and the winding can be performed at a high density.
[0022]
When the skew 3a is formed only at the tip of the tooth 9, the range of the stator skew angle θs is expressed by the following equation. In the following equation, β is the angle [degree] formed by the tip width in the winding portion of the stator, and γ is the angle [degree] formed by the slot opening width in the stator, respectively, as viewed from the center point O of the stator 1. Angle.
[0022]
0 <θs ≦ α-β-γ (1)
[0023]
When the skew angle of the slot pitch angle α of the stator 1 is formed by the sum of the stator skew angle and the rotor skew angle, the following equation is established between the rotor skew angle θr and the slot pitch angle α of the stator.
[0024]
θr <α (2)
[0025]
That is, if the stator skew angle θs is small, the rotor skew angle θr becomes very large, but it means that the skew can be obtained only up to the stator slot pitch angle α.
[0026]
Further, when the stator skew angle is maximized, that is, θs = α−β−γ, the rotor skew angle is minimized. That is, if the sum of the rotor skew angle and the stator skew angle is the stator slot pitch α, the following equation is obtained.
[0027]
β + γ ≦ θr (3)
[0028]
The following equation is obtained from the above equations (2) and (3).
β + γ ≦ θr <α (4)
[0029]
In this way, by forming the stator skew 3a so that the stator 1 and the rotor skew 22a are inclined and intersect with each other, the optimum skew angle as a whole can be obtained with a small rotor skew angle θr. As a result, the generation of harmonic torque can be reduced, the slot opening width of the rotor 20 can be increased, the length of the equivalent secondary conductor can be shortened, the secondary resistance can be reduced, and the loss can be reduced. be able to. In addition, it becomes easy to die-cast aluminum which is the secondary conductor 26, and the amount of aluminum can also be reduced. Further, by making the sum of the rotor skew angle θr and the stator skew angle θs near the stator slot pitch α, the harmonic torque due to the harmonics of the stator slot 11 is effectively suppressed, and vibration and noise are further reduced. Can be reduced.
[0030]
Next, from the viewpoint of the electromagnetic excitation force theory of a single-phase induction motor, the relationship between the skew angle and vibration noise or torque characteristics will be described. First, assuming that the number of stator slots is Ns and the number of pole pairs is p, the gap magnetic flux density harmonic due to the harmonics of the stator slot 11 becomes NsKs ± p order spatial harmonics (Ks is an arbitrary integer). The stator magnetomotive force harmonic is a 4pKp ± p order spatial harmonic (Kp is an arbitrary integer). Therefore, when the number of rotor slots is Nr, the spatial harmonic order of the electromagnetic force wave in the air gap is given by the following equation.
[0031]
A ± 2p, A ... (5)
Here, A = NsKs + NrKr + 4pKp (Kr is an arbitrary integer)
[0032]
The time harmonic order at this time is given by the following equation, where slip is s.
[0033]
B ± 2, B (6)
Where B = NrKr (1-s) / p
[0034]
The harmonic torque takes into account the magnetomotive harmonic of the rotor 20, and the magnetomotive harmonic has the same order as the harmonic of the stator slot 11 and the stator magnetomotive harmonic, and therefore, the above equation (5) Becomes the following formula.
[0035]
A + C ± 2p, A + C (7)
Here, C = Ks′Ns + 4Kp′p (Ks ′ and Kp ′ are arbitrary integers)
[0036]
If there is a value of each Ks, Kp, Ks ′, Kp ′ that is zero in both equations (6) and (7), harmonic torque is generated.
[0037]
In the above equation (7), Ks ′ and Kp ′ are arbitrary integers related to the magnetomotive harmonic of the rotor 20, and in order to generate this magnetomotive harmonic, the harmonic and magnetomotive harmonic of the stator slot 11 are generated. An eddy current due to waves needs to be generated in the secondary conductor 26 of the rotor 20. The harmonics of the stator slot 11 have a spatial harmonic order of Ns ± p (the highest harmonic of Ks = 1), and can be greatly reduced by forming a skew near the stator slot pitch.
[0038]
Embodiment 2. FIG.
FIG. 6 is a front view showing the teeth of the stator in the second embodiment. In the first embodiment, the case where the teeth 9 of the stator 1 are straightened has been described. However, as shown in FIG. 5, the tip 9a of the winding portion 9b of the teeth 9 is narrowed and the root 9c of the teeth 9 is thickened. You may form in the trapezoid shape. If formed in this manner, the angle θs of the stator skew 3a can be increased without changing the size of the stator slot 11, and accordingly, the rotor skew angle θr can be reduced accordingly.
[0039]
In the case of the concentrated winding stator, the winding 9b of the teeth 9 of the stator 1 has the largest magnetic saturation at the root 9c and the tip 9a is small due to the influence of the slot leakage magnetic flux of the stator 1. Therefore, the root 9c is thickened. By doing so, adverse effects due to magnetic saturation can be reduced.
[0040]
In this embodiment as well, the sum of the rotor skew angle θr and the stator skew angle θs is in the vicinity of the stator slot pitch α, thereby effectively suppressing the harmonic torque due to the harmonics of the stator slot 11. In addition, vibration and noise can be further reduced.
[0041]
Embodiment 3 FIG.
FIG. 7 is a perspective view of the rotor 20 according to Embodiment 3 of the present invention. As shown in the figure, the rotor skew 22a is formed in a V shape that bends in the center in the axial direction, and the stator skew 3a (not shown) also intersects with the rotor skew 22a differently, that is, in the center in the axial direction. Thus, it may be formed in a V shape that bends in a direction different from the rotor skew 22a. If formed in this way, the axial thrust force caused by the skew 22a can be reduced.
[0042]
When a V-shaped skew is formed only on the rotor 20, the necessary skew angle must be obtained at half the thickness of the rotor 20, so that the angle of the skew in the axial direction becomes very steep. Although difficult to realize, by forming a skew on the stator 1 side as well, it is possible to reduce the axial thrust force while reducing the axial angle of the rotor skew 22a, and to reduce the electromagnetic excitation force due to harmonics. Can also be reduced.
[0043]
Also in this embodiment, the sum of the rotor skew angle θr and the stator skew angle θs is set near the stator slot pitch α, thereby effectively suppressing the harmonic torque due to the harmonics of the stator slot 11. In addition, vibration and noise can be further reduced.
[0044]
【The invention's effect】
According to the present invention, electromagnetic excitation force due to harmonics can be reduced, vibration and noise can be reduced, loss due to the secondary resistance of the rotor can be reduced, and the secondary conductor of the rotor can be die-cast. It becomes easy.
[0045]
In addition, electromagnetic excitation force due to harmonics can be reduced, vibration and noise can be reduced, and magnetic saturation of the winding portion of the stator teeth can be reduced.
[0046]
In addition, the electromagnetic excitation force due to the harmonics can be reduced, vibration and noise can be reduced, and the axial thrust force can be reduced.
[0047]
Furthermore, electromagnetic excitation force due to harmonics can be effectively reduced, and vibration and noise can be further reduced.
[Brief description of the drawings]
FIG. 1 is a front view of a stator of a single-phase induction motor according to a first embodiment.
FIG. 2 is a front view of a stator and a rotor of the single-phase induction motor in the first embodiment.
FIG. 3 is an exploded perspective view of the stator of the single-phase induction motor in the first embodiment.
4 is an exploded perspective view of the rotor of the single-phase induction motor according to Embodiment 1. FIG.
5 is a partial development view of a stator facing surface of a rotor of a single-phase induction motor according to Embodiment 1. FIG.
6 is a front view showing teeth of a stator of a single-phase induction motor according to Embodiment 2. FIG.
7 is an exploded perspective view of a rotor of a single-phase induction motor according to Embodiment 3. FIG.
[Explanation of symbols]
1 Stator, 3a Stator Skew, 9 Teeth, 11 Stator Slot, 20 Rotor, 22 Rotor Slot, 22a Rotor Skew, 22v V Skew, 26 Secondary Conductor.

Claims (3)

A stator having a plurality of teeth and a plurality of slots formed between the teeth;
A stator winding wound around each of the teeth,
A rotor having a cage-shaped secondary conductor passing through the slot and rotating by magnetic flux generated from the stator;
The stator slots are formed by a predetermined angle skew only the tip portion of the tooth Rutotomoni,
The slot of the rotor is skewed so that the inclination direction is different from the slot of the stator ,
The sum of the skew angle of the stator and the skew angle of the rotor is approximately equal to the slot pitch angle of the stator, and the skew angle of the rotor is determined by the angle β formed by the tip width in the winding portion of the stator. A single-phase induction motor characterized in that the slot opening width in the stator is equal to the sum of angles γ formed .   The single-phase induction motor according to claim 1, wherein a width of the front end portion of the teeth of the stator is narrower than a width of the root portion.   The skew of the stator slot has a V shape that is bent near the center in the axial direction, and the skew of the rotor slot has a V shape that is bent near the center in the axial direction in a direction different from the skew of the stator. The single-phase induction motor according to claim 1.

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