JP4677026B2 - Hybrid two-phase permanent magnet rotating electric machine - Google Patents

Description

  The present invention is a stepping motor in which two two-phase stators and eight hybrid permanent magnet rotors having eight main poles as winding poles are provided close to the same axis and magnetized in opposite directions to each other. And so on.

  There is a demand for rotating electrical machines such as stepping motors that are small, have high torque and low vibration and are used in OA equipment and the like. The following prior art is one of the means for solving this problem.

Japanese Published Patent No. 3-212149

1) When trying to obtain a large torque with a stepping motor having a hybrid (hereinafter abbreviated as HB) structure, the stator thickness is increased in the axial direction to increase the torque. At this time, the motor diameter is determined. Since the area from which the magnetic flux of the permanent magnet is generated is determined, the magnetic flux does not increase even if the thickness of the magnet is simply increased. Therefore, two magnets are used, and two HB type rotors are provided in the axial direction. That is, the rotor has a permanent magnet sandwiched between two magnetic rotors having a plurality of magnetic teeth at an equal pitch on the outer periphery, and an HB type rotor formed by shifting the tooth pitch by 1/2. A multi-stage rotor is used in which two or more are arranged in the direction through spacers such as nonmagnetic disks. However, due to the following problems with the rotor and the problems with the stator, a sufficiently large torque could not be obtained with low vibration.
2) The problem with the rotor is that a non-magnetic disc (33 in FIG. 3 to be described later) having a predetermined thickness for magnetic insulation is interposed between the two-stage rotor described above and magnetized in the same direction in the axial direction. However, the non-magnetic disk part does not generate torque, and in the vicinity, the interlinkage magnetic flux from the rotor is reversed in the adjacent boundary part of the two magnetic circuits, so the direction of weakening, that is, the boundary between the two magnetic paths Induction of magnetic field interference was a hindrance to high torque. Further, if the non-magnetic plate is not thick enough, there is a problem that a leakage magnetic flux is generated and the torque does not appear as expected.
In addition, the use of non-magnetic disks such as aluminum increases the price of the rotating machine.
3) Increasing the stator stack thickness with multiple stages of rotors increases the cogging torque due to the magnetic flux of the permanent magnet, and this cogging torque generates a problem of generating vibration torque during motor rotation and deteriorating positioning accuracy. Therefore, in order to reduce the cogging torque, the inductor tooth pitch provided at the tip of the main pole of the stator is changed by a certain angle with respect to the rotor tooth pitch as an example of the prior art for reducing the cogging torque. However, when the rotor is a multi-stage composite rotor, the influence of the variation in magnetic resistance in the stacking direction of the stator when the stator is thick is increased. Or, if there are six inductor teeth of the stator, for example, six, the spatial harmonics cannot be sufficiently reduced due to the influence of the permeance depending on the inner position, the central position, and the outer position, so the cogging torque is sufficient. There was a problem with the stator that it was difficult to cancel. The cogging torque is generated due to the presence of the fourth component of the permeance, and is caused by variations in component accuracy, variations in magnetoresistance, non-uniform air gap, variations in magnetic properties of magnetic materials, and the like.
There are problems with the rotor and stator as described above, and it is a problem to solve these problems.

The present invention is realized by the following means.
"Means 1"
A stator core with six inductor teeth at the tip of the main pole, which is connected radially in a polygon or ring shape, including a quadrilateral, and radially arranged in the radial direction, is stamped from the magnetic plate. And a permanent magnet magnetized in the axial direction by two rotors having 50 teeth provided at an equal pitch in a rotatable manner through an air gap by rotating and laminating by 90 degrees to form a two-phase stator. Are separated by a half pitch of the tooth pitch to form a unit rotor, and two sets of unit rotors a and b are provided close to each other on the common rotating shaft, and the unit rotors a and b The adjacent rotors have the same tooth position and are magnetized to the same polarity to form a rotor, and the two unit rotors are separated in the axial direction by the above stator via an air gap. Hybrid rotation with two a and b magnetic paths of rotor permanent magnet flux In electric
The six inductor tooth pitches provided at the tips of the eight main poles of the stator are different from the rotor tooth pitch. If the six teeth are sequentially designated as T1 to T6, the centers of the main poles are T3 and T4. When the pitch of T1 and T2 is γ, the pitch of T2 and T3 is β, and the rotor tooth pitch is c, α + 2β + 2γ <5c, α ≠ β = Γ or α ≠ β ≠ γ, and the six permeance vectors in the fourth-order plane are set in each magnetic path by the unequal pitch inductor effect in each main pole in the a and b magnetic circuits. First balance,
Furthermore, the variation of the six permeance vectors of the fourth component of the permeance caused by the thickness and magnetic direction of the magnetic plate of the stamped stator is a superposition effect of four types of permeance vectors that can be obtained by the 90 ° rotation lamination. Utilizing the shortened magnetic path length effect by the a and b magnetic paths that are secondarily balanced in the path and further divided into two in the axial direction and the magnetic field non-interference effect at the boundary between the two magnetic paths, the four kinds of permeances by the 90-degree rotation lamination A fourth-order harmonic permeance component is obtained by further superimposing six permeance vectors of the fourth-order component, which are second-order balanced by the vector superimposition effect, between the magnetic paths a and b to increase the third-order balance to enhance the balance effect. Rotating electric machine that has the triple function.
"Means 2"
In the means 1, when the tooth widths corresponding to the six teeth T1 to T6 are t1 to t6, respectively, the tooth widths of the six teeth are different from each other at t1 to t3 on one side of the main polar symmetry line. And the ratio of the tooth width to the tooth pitch of each tooth, t1 / α, t2 / β, and t3 / γ are approximately 0.4. .
"Means 3"
A permanent magnet type rotating electrical machine characterized in that in means 1 or 2, the permanent magnet used in the rotor is a ferrite permanent magnet having a residual magnetic flux density of about 0.5 T or less.
"Means 4"
In the means 1, 2, and 3, the permanent magnet of the rotor is a non-magnetized permanent magnet type that is assembled as a motor, and then has a time difference in the axial direction and is magnetized in the forward direction and in the opposite direction. Rotating electric machine.

1) Adopting a rotor in which two HB rotors are magnetized opposite to each other in the axial direction and are close to each other on the same axis, there is less leakage flux as in the prior art, and there is no decrease due to interference of different direction fluxes. Since the magnetic flux is in the same direction at the boundary between the two magnetic paths, a magnetic field non-interference effect can be obtained, and space is not wasted, so high torque can be obtained.
2) By adopting an unequal pitch tooth position configuration in which the pitch of the six inductor teeth is different from the adjacent tooth pitch, the degree of freedom for eliminating the fourth-order spatial harmonics can be increased.
3) By changing the width of at least one pair of teeth selected from two more symmetrical tooth groups, the influence of the magnetic circuit unbalance and the influence of the permeance difference due to the stator inductor tooth position can be canceled. The effect of reducing harmonics can be enhanced.
4) Or two magnetic paths are formed by magnetic fluxes from the permanent magnets of the rotor in the axial direction by a rotor that magnetizes two HB rotors in opposite polarities in the axial direction and closes them coaxially. By using a shortened short magnetic circuit, it is possible to obtain a magnetic circuit length shortening effect that makes the magnetic flux density more uniform in each magnetic circuit portion, and it is possible to enhance the harmonic reduction effect.
5) The HB type stepping motor is designed to have an air gap between the stator and the rotor of about 0.05mm, so the magnetic resistance between the two magnetic circuits described above due to the rotor increases the motor length due to slight variations in the air gap. Variations are possible. In this case, the conventional equal pitch inductor method has a problem that the harmonics cannot be sufficiently reduced. On the other hand, harmonics with a high degree of freedom due to the unequal pitch effect of the inductor tooth pitch, and in addition to this, the harmonics are canceled twice due to the unequal tooth width effect. The problem due to the magnetoresistive difference can also be solved by the present invention.
6) Further, if the tooth width ratio is appropriately selected, the rotor magnetic flux is linked with the stator coil while minimizing the leakage magnetic flux, which is advantageous for high torque. The value obtained by dividing the inner position small tooth width by the first pitch, the value obtained by dividing the middle position small tooth width by the second pitch, and the value obtained by dividing the small tooth width at the outer position by the third pitch. 0.4. This value is obtained by magnetic field analysis using a computer.
7) Further, in the present invention, if the number of inductors is six, the fourth-order component is canceled by reducing the fundamental wave component of the permeance by the effect of the unequal pitch vernier method, and the main pole First, the permeance vectors in the six fourth harmonic planes are balanced first.
8) The stator is press-punched from a magnetic plate such as a silicon steel plate and rotated 90 degrees to laminate the difference between the magnetic resistance and the plate pressure deviation in the rolling direction and the direction perpendicular to the existing rolling direction even with a non-oriented silicon steel plate. Can be eliminated, and a second-order balance can be achieved to make the fourth-order component of permeance uniform among the eight main poles. Further, it has a third-order balance function of the superimposed average effect of the permeance vector between the two magnetic paths.
9) Even if it is desired to reduce the price with the same size and the same torque as the conventional motor, a low-grade magnet such as a ferrite magnet can be used as a short magnetic circuit by dividing the structure into two magnetic circuits in the axial direction according to the present invention. . In addition, since the operating point is stabilized by the flat slope of the BH curve of the ferrite magnet, a uniform magnetic flux density effect is obtained, resulting in a low vibration motor. This is because when the BH curve has a flat inclination, the change in the magnetic flux value can be reduced even if the operating point moves slightly due to variations in the air gap or the like.

  This will be described below with reference to the drawings.

FIG. 1 shows an example of the present invention, in which a rotor viewed from the axial direction of a rotating electrical machine by a combination of a stator of a two-phase eight main pole machine and a special two-stage HB type rotor has an N-pole portion and an S-pole portion. It is a cross-sectional view including a figure and an axis. Six inductor teeth are provided at the tip of the main pole, which is the eight winding poles, and the main pole portions facing the rotor N pole are designated as N1 to N8, and facing the rotor S pole. The eight main pole portions are designated as S1 to S8. One-phase winding is wound around N1 and S1, N3 and S3, N5 and S5, and N7 and S7 with the same coil to form one phase, and the remainder is wound in the same manner to form two phases. The solid line arrow in the N pole side stator indicates the flow of magnetic flux from the N pole rotor, and the solid line arrow in the S pole side stator indicates the magnetic flux from the N pole rotor toward the S pole rotor. Show the flow. The rotor is composed of two rotors each having a plurality of teeth provided at equal pitches through an air gap. The permanent magnets magnetized in the axial direction are shifted from each other by ½ pitch of the tooth pitch. When two pairs of unit rotors are sandwiched and unit rotors a and b are provided, they are provided close to each other on a common rotation axis, and the adjacent rotors of unit rotors a and b have the same tooth position and the same tooth position. An HB type rotating electrical machine having two magnetic circuits separated in the axial direction by two unit rotors of the rotor is formed by being magnetized to polarity. Although the part number is omitted, the rotor is rotatably supported by the stator via a bearing and front and rear brackets.
FIG. 2 is a sectional view of the stator portion and the rotor portion in the axial direction. Reference numeral 1 denotes a stator core, and 21, 22, 23, and 24 denote rotors in which silicon steel plates or the like are laminated. When 50 magnetic teeth are provided on the outer periphery at an equal pitch, a stepping motor with a step angle of 1.8 ° is obtained. In FIG. 2, 25 and 26 are disk-shaped permanent magnets which are magnetized so as to have opposite polarities to each other. Therefore, in FIG. 2, 21 and 24 are magnetized to S polarity and 22 and 23 are magnetized to N polarity. At this time, 21 and 22 and 23 and 24 are shifted by a half of the tooth pitch. 22 and 23 are in principle the same tooth position. Unit rotor a is composed of 21, 25, 22 and unit rotor b is composed of 23, 26, 24. The dotted arrow Φ1 shown on the stator 1 is the magnetic flux and its magnetic path by the unit rotor a, Φ2 is the magnetic flux and its magnetic path by the unit rotor b, and Φ1 and Φ2 at the central portion in the axial direction of the stator 1 It can be seen that the two directions of magnetic flux are not weakened due to the interference effect because they are in the same direction. This will be referred to as a boundary magnetic field non-interference effect between the two magnetic paths. Compared with the case of one rotor, the magnetic path in the axial direction is halved, so that the shortened magnetic path length effect can be exhibited, and the magnetic resistance is halved, so that a rotating electrical machine with less magnetic loss and less variation can be obtained. In FIG. 2, 3 is a coil and 4 is a rotor shaft. The rotors 22 and 23 magnetized to the same polarity may be adjacent or close to each other. In this configuration, there is a leakage flux between the outer peripheral portions of the permanent magnets between the unit rotors 21 and 22 opposed to each other with the permanent magnet interposed therebetween, but there is no leakage flux between the rotors magnetized to the same polarity, and most of the magnetic flux is Since it goes to the stator, there is very little wasted magnetic flux and high torque can be obtained.

FIG. 3 is a view in which the stator is the same as FIG. 2 and only the rotor is different. In order to obtain a high torque by increasing the length in the axial direction, a two-stage rotor shown in FIG. 3 is also conceivable. Reference numerals 27, 28, 29, and 30 denote rotors, which are arranged so as to be shifted from each other by ½ pitch of the tooth pitch, and magnetize the two permanent magnets 31 and 32 in the same direction in the axial direction as illustrated. . Therefore, a nonmagnetic magnetic insulator 33 is required. If 33 is made thinner in the axial direction, the leakage magnetic flux increases between 28 and 29, and if it is made thicker, the area facing 1 is reduced. Therefore, the torque is reduced in the same stator as compared with FIG. Further, the magnetic fluxes Φ1 and Φ2 generated by the two unit rotors 27, 31, 28, 29, 32, and 30 are opposite to each other at the central portion in the axial direction of the stator 1. Magnetic flux interferes and weakens, causing problems such as distortion and magnetic flux reduction. For this reason, the magnetic flux density becomes non-uniform and the configuration is not suitable for low vibration.

FIG. 13 is a diagram showing a conventional ordinary two-phase HB type rotating electric machine, which is composed of one unit rotor, and thus the outer diameter of the permanent magnet does not change even if the motor length is increased in the axial direction in this configuration. Therefore, the magnetic flux from the obtained permanent magnet does not increase so much even if the magnet thickness is increased, and a large increase in torque cannot be expected. The basic configuration of the stator is the same as in FIG.

FIG. 4 is a view in which the rotor is opposed to one main pole in which the inductor teeth of Patent Document 1 as an example of the cited prior art have equal pitch teeth. In Patent Document 1, the pitch of the stator tooth pitch of the stator is 6.9 ° and the rotor tooth is 50, and the mechanical angle of the rotor tooth pitch of 7.2 ° is narrowed by 0.3 °. An example is disclosed. In this case, when the deviation angle between the stator tooth position and the rotor tooth position in FIG. 4 is set to 7.2 ° as the electrical angle of 360 °, θ1 to θ6 are displayed as electrical angles, and θ3 = θ4 = (0 .3 ° / 2) (360 ° / 7.2 °) = 7.5 °,
θ2 = θ5 = (0.3 ° + 0.3 ° / 2) (360 ° / 7.2 °) = 22.5 °, θ1 = θ6 = (0.3 ° + 0.3 + 0.3 ° / 2) (360 ° / 7.2 °) = 37.5 °, the fourth-order spatial harmonic component P4 of the permeance constituting the cogging torque can be calculated by the following equation.
P4 = cos4θ3 + cos4θ2 + cos4θ1 + cos4θ4
+ cos4θ5 + cos4θ6
= 2 {cos30 + cos90 + cos150} = 0 (1)
If the fourth-order permeance component of these six small teeth is displayed as a polar coordinate vector on the fourth-order plane, FIG. 5 is obtained and the sum of the vectors becomes zero. FIG. 4 is a diagram in which the vectors when the rotor is positioned symmetrically with respect to the center line of the main pole are balanced as shown in FIG. Then, when the relative position of the stator and the rotor is shifted by λ degrees with respect to FIG. 4, the vector in the fourth-order plane is obtained by rotating six vectors by λ / 4 degrees with respect to FIG. Therefore, the sum of these vectors is always zero, and each of the eight main poles is balanced. Accordingly, if all eight main poles are perfectly symmetric, one main pole may be examined. Theoretically, if this is done, the cogging torque is canceled and the vibration is reduced.
In this case, the fundamental wave component that becomes the flux linkage and becomes the motor torque is given by the following equation.
P1 = cos θ3 + cos θ2 + cos θ1 + cos θ4
+ cos θ5 + cos θ6
= 2 {cos7.5 + cos22.5 + cos37.5} /6=0.902 (2)
That is, 90% remains as a torque component.
However, this is based on the assumption that the permeance of the 6 stator inductor teeth is exactly the same. In FIG. 4, the six inductor teeth provided at the tips of the eight main poles of the stator are arranged adjacent to each other with a pair of two inner position teeth adjacent to each other located in the center. The intermediate position tooth and the outer position tooth adjacent to the intermediate position have different distances as viewed from the main pole center position. Is also different. For this reason, there is a problem that the fourth-order component does not actually become zero like the calculated value.

FIG. 6 is a diagram for explaining six inductor teeth of a stator having an unequal pitch and an unequal tooth width adopted in the present invention. In the two-phase 8-main pole type HB type stepping motor, a rotating electric machine having a rotor step number of 50 and a step angle of 1.8 ° and one rotation of 200 steps is widely used. In that case, if six inductor teeth are provided at the tip of the eight main poles, the number of stator teeth is 48, approaching the number of rotor teeth 50, and these six are the limit. The teeth of the six inductor teeth are T1 to T6 from the left in the figure, their tooth widths are t1 to t6, the tooth gap width is U1 to U5, and U3 is located in the center. As for the tooth pitch, the pitch of the two teeth having the center width T3 and T4 is α, both sides thereof are β, and both outer pitches are γ. The tooth pitch, tooth width, and groove width are line targets from the center line of U3. Therefore, t1 = t6, t2 = t5, t3 = t4, U1 = U5, U2 = U4.
In this way, when the center of the rotor tooth groove coincides with the center of U3 as shown in the figure and the rotor and the stator face each other, the deviation angle between the rotor teeth and the six inductor teeth of the stator The degree of freedom in which δ1 to δ3 can be set to desired values is far greater than that of the prior art stator equal pitch tooth system. Further, if the teeth of the outermost T1 and T6 and the teeth of the inner T3 and T4 have the same tooth width, the permeance is different due to a difference in magnetic resistance or a leakage magnetic path difference depending on the tooth position. For example, the leakage magnetic path of the magnetic flux from the teeth changes depending on the shape of the tooth gap, so that the outermost teeth and other teeth are different. A means for correcting this to make the permeance of the six teeth uniform is the unequal tooth width inductor tooth. For example, when six teeth are equal in width and the permeance of the outermost T1, T6 teeth is smaller than that of the inner T3, T4 teeth, the tooth width is set to t1 = t6> t3 = t4.
U1 to U3, t1 to t3, α, β, and γ may all be different from each other, but at least one needs to be different. At this time, the tooth width ratio is a value obtained by dividing the inner position small tooth widths t3 and t4 by the first pitch as described above, a value obtained by dividing the intermediate position small tooth widths t2 and t5 by the second pitch β, and the outer side. It is desirable for increasing torque that the value obtained by dividing the small tooth width t1 of the position by the third pitch γ is approximately 0.4. That is, t1 / α = t2 / β = t3 / γ = 0.4. If this value is less than 0.4, the magnetic flux of the teeth is likely to be saturated, and if it is too large, the leakage flux increases. This optimum value 0.4 is obtained from computer simulation and experimental data.

FIG. 7 shows an example in which impedance vectors in the fourth plane due to unequal pitch inductor teeth are balanced. If α = 6.66 ° and β = γ = 7.02 ° in FIG. 6, the fourth-order permeance vectors of the stator teeth T1 to T6 are V1 to V6, respectively. The deviation angles δ1 to δ6 are mechanical angles and have values in () in FIG. 7, and the sum of the vectors becomes zero. Even if V2 and V5 are larger than other vectors, they are canceled. Furthermore, it is canceled individually within the three vectors V1 to V3 and also within the two groups within V4 to V6. This means that the unequal pitch method has a higher degree of freedom of balance than the conventional method of FIG. Although the number Ns of inductors is shown in the case of 6, if Ns = 5, the cancellation is performed with five vectors on the fourth plane. This will be referred to as a first-order balance of permeance vectors in the fourth-order plane for the sake of explanation.
When the number of rotor teeth is 50, it has been stated that the limit of 6 main teeth and 8 small teeth is the limit. However, since the coil is wound from the gap between the 8 main poles, the gap should be made as large as possible. I want to make the winding work easier. For this purpose, the following relational expression is required from FIG. 6 between the tooth pitch α, β, γ and the rotor tooth pitch c, which eliminates the fourth component of the permeance that creates cogging torque with unequal pitch inductor teeth. become.
{(Α + 2β + 2γ) / 5} <c (3)
The left side of the expression (3) is the average value of the tooth pitches in FIG. 6, and α, β, and γ may exceed the rotor tooth pitch c, but the average value of the five pitches is smaller than the rotor tooth pitch. It will be necessary.

FIG. 7 shows an example in which the tooth pitches corresponding to α, β, and γ are α ≠ β = γ and all values are smaller than c = 7.2 °. However, FIG. 8 shows another unequal pitch tooth of the present invention. This is an example of the position α ≠ β ≠ γ, where α = 6.66 °, β = 6.84 °, γ = 7.38 °> c = 7.2 °, and the rotations facing each other at this time The deviation angles θ1 to θ6 with respect to the child teeth are the values shown in FIG. The fourth-order permeance component in this case is calculated as follows.
P4 = cos4θ3 + cos4θ2 + cos4θ1 + cos4θ4
+ cos4θ5 + cos4θ6
= 2 {cos4 * 0.27 * 360 / 7.2 + cos4 * 0.63 * 360 / 7.2
+ cos 4 × 0.45 × 360 / 7.2}
= Cos 54 ° + cos 126 ° + cos 90 ° = 0.5877−0.5877 = 0 (4)
In this case, the fundamental wave component that becomes the flux linkage and becomes the motor torque is given by the following equation.
P1 = cos θ3 + cos θ2 + cos θ1 + cos θ4
+ cos θ5 + cos θ6
= 2 {cos 13.5 ° + cos 31.5 ° + cos 22.5 °} /6=0.9163 (5)
That is, 91.6% remains as a torque component, which is superior to 90% of the value of equation (2), which is the value of the conventional equal pitch method, and the unequal pitch tooth method is advantageous for obtaining torque. I know that there is.

FIG. 9 shows a stator core used in the present invention, which is rotated and laminated by 90 degrees when punched out from a silicon steel hoop material with a presswork. The silicon steel hoop material is a magnetic iron plate having a thickness of about 0.5 mm containing several percent of silicon to reduce eddy current iron loss, and is wound in a roll shape. Then, the target core is continuously extracted by progressive press punching, and then the thickness is laminated and fixed to a desired size to obtain the target product. FIG. 9 shows a stator core with two phases and eight main poles, which is made by press punching from a silicon steel hoop material. The Z direction, which is the longitudinal direction, is the rolling direction of the silicon steel sheet hoop material, and is the roll winding direction of the hoop material. The width of the silicon steel sheet hoop material is usually slightly larger than the outer dimension of the stator core in order to reduce the scraps discarded in the progressive press punching. For convenience of explanation, the illustrated stator core is described by providing orthogonal coordinates of the Z axis in the longitudinal direction of the hoop material and the LR axis perpendicular thereto. The stator core of an 8-main pole 2-phase HB type stepping motor having 8 main poles A to H is laminated and the thickness is adjusted to a desired size and automatically fixed by caulking or the like. To obtain the desired stator. At this time, in the present invention, the punched stator core is rotated and laminated by 90 degrees to form a stator, so that the permeance becomes uniform in the four-unit lamination of the stator, and as a result, the fourth-order permeance component becomes uniform, Since it can be canceled by balancing, it will be explained that it exhibits a very remarkable effect in reducing cogging torque and vibration caused by the presence of the fourth-order permeance component.
In general, the first reason for rotating and laminating 90 degrees to form a stator is to cancel the difference in magnetic flux passage between the rolling direction of the silicon steel sheet hoop material and the direction perpendicular thereto.
The second reason is that the hoop material is thinly stretched by a rolling method, but the gap between the rolling rollers tends to be biased, resulting in a difference in thickness between the L side and the R side. In this case, if a non-rotated laminated product is used, the greater the number of laminated products, the greater the total thickness difference between the L side and the R side. If a bracket having a bearing is attached to such a stator, the shaft center is inclined, and the air gap between the stator inner diameter and the rotor outer diameter becomes uneven depending on the location, which deteriorates the performance of the stepping motor. The 90 degree rotation lamination is in the cancellation of this integrated thickness deviation. Furthermore, the third reason is that the fourth harmonic permeance vector can be canceled from the influence of the variation in the permeance between the Z direction and the RL direction of the silicon steel sheet and the thickness difference in the RL direction. These will be described next.

In general, non-directional magnetic plates are used for silicon steel plates for motors. However, even in the case of non-directional magnetic plates, there is a difference in permeance between the rolling direction and the direction perpendicular thereto. It is assumed that the stator core is punched from the silicon steel sheet hoop material at the position of FIG. 9 so that the magnetic flux easily passes in the Z direction and the permeance is large and the permeance is small in the LR direction. In this case, the permeance of the main poles A, D, E, and H whose axial direction of the main pole is close to the Z direction is increased. Further, the permeance of the remaining main poles B, C, F, and G whose axial directions of the main pole are close to the LR direction becomes relatively small. In this case, considering the main pole A part, since the eight main poles are symmetrical and arranged at 45 degree intervals, the configuration by 90 degree lamination of the main pole A part is four times 90 degree lamination if laminated by left rotation. It becomes (A + C + E + G), and this structure is repeated.
Similarly, considering the main pole H portion, the 90-degree stacking configuration of the main pole H portion is (H + B + D + F) by 90-degree stacking four times, and this is a repeated configuration. Then, the main pole A part has two parts A and E among the parts with large A, D, E, and H permeances, and the main pole H also has two parts with large D and H permeances, and the rest Both of the two have two B, C, F, and G permeances that become smaller, and the average permeance in the four rotation stacks is the same value. Since this four-rotation lamination is repeated as a unit lamination, both values are the same. The permeance average value of each main pole converges to the same value by increasing repetition even if it is not necessarily an integral multiple of this unit stack. The average permeance is the same for the other main poles for the same reason. When considering the balance in the fourth plane with the six permeance vectors of the inductor teeth T1 to T6 by the inductor of the main pole of the fourth harmonic permeance, each of the eight main poles is within the unit stack. Since it is composed of two stator cores each having large and small permeances, the permeance of each main pole is always the same in the unit stack. If the 90 degree rotation stacking is not performed, the main poles A, D, E, and H have large permeances, the remaining B, C, F, and G are small, and the six permeance vectors in each main pole are balanced. Thus, a difference occurs between the eight main poles, and the cogging torque or the like is increased or the noise is increased in the entire motor.

Next, consider a case where the stator core is punched from the silicon steel plate at a position as shown in FIG. In this case, a hoop material is assumed in which the R side is thick and the L side is tapered and the thickness is reduced. However, in order to simplify the description, of the eight main poles of the stator, the R side It is assumed that A, B, C, and D are thicker than E, F, G, and H, and the permeance is larger when the thickness is larger. Also in this case, the configuration of the main pole A part is (A + C + E + G) and the H part is (H + B + D + F) in the unit lamination of every four silicon steel sheet lamination parts by 90 degree rotation lamination. Therefore, the average value of the permeance is the same, and in the same way, the balance in the fourth plane is obtained with the same number of vectors as the six inductors T1 to T6 by the main pole inductor of the fourth harmonic permeance. When considering, since each of the eight main poles is composed of two stator cores each having a large permeance and a small permeance, the average value of the six permeance vectors is the same. Therefore, the permeance vector in the fourth plane in the main pole is easily balanced, and the permeance vector in the fourth plane in the entire motor is easily balanced.

FIG. 10 shows a case in which a stator core having a two-phase eight main pole and six inductors of each main pole and having a substantially square outer periphery is punched. Considering punching from a hoop material close to one side of a square in order to reduce material waste, the Z direction is the winding direction of the hoop material. In this case, it is assumed that the winding direction of the silicon steel sheet is the Z direction, the L side is thicker, and the thickness is thinner toward the R side. The six inductor teeth of each of the eight main poles are denoted by reference numerals T1 and T6 only for simplification of illustration, but are set to T1 to T6 from the left end in the clockwise direction. The fourth permeance vectors of the six inductors T1 to T6 are V1 to V6, respectively. In this case, the main pole A becomes thinner from T1 to T6. Strictly speaking, the magnitude of the fourth-order permeance vector gradually decreases from T1 to T6, but in order to simplify the explanation, the Z axis is Suppose that the fourth permeance vector is large on the L side of the Z axis and small on the R side. Accordingly, the fourth permeance vector of each of the six inductor teeth of the main poles F, G, H is the same size and larger than that of the main poles B, C, D, and the main poles B, C on the R side of the Z axis , D are the same in size. In this case, in the main pole A, T1, T2, and T3 are large with the same size, and T4, T5, and T6 are small with the same size. In the main pole E, T4, T5, and T6 are the same size and large, and T1, T2, and T3 are the same size and small. If rotation lamination is performed under such conditions, A + C + E + G becomes a unit lamination in the main pole A portion. Since the main pole E has small vectors T1, T2 and T3 and large vectors T4, T5 and T6, A + E is averaged. Since C + G is also averaged, A + C + E + G is superimposed and averaged at the main pole A portion. The other main poles are similarly superposed and averaged. As a result, the six superimposed vectors in the fourth-order plane are point-symmetric and balanced. Next, the above description will be described using a fourth-order plane permeance vector with reference to FIG. A, C, E, and G in FIG. 11 represent the fourth-order plane permeance vectors of T1 to T6 of the main poles A, C, E, and G in FIG. 10 as V1 to V6, respectively. As described above, the permeance vector of the main poles A, C, E, and G of one stator core is as shown in FIG.
If the stator core of FIG. 11 is a non-rotating laminate, V1 to V3 are larger than V4 to V6 in the main pole A as shown in FIG. In the main pole C part, six vectors are uniformly small as shown in C of FIG. In the main pole E, V1 to V3 become smaller than V4 to V6 as shown in E of FIG. In the main pole G portion, six vectors are uniformly large as indicated by G in FIG. If the A, C, E, and G diagrams in FIG. 11 are superimposed, it can be seen that the synthesized six vectors are averaged and uniformized.
For simplification of explanation, the vector size is set to two types on the left and right sides of the Z axis, but even if V1 to V6 are gradually different in size, for example, in the unit laminated portion of the main pole A, A + E Since these six vectors are averaged to the same value, A + C + E + G is also averaged. This is an effect by 90 degree | times rotation lamination | stacking, and the other main pole part is also the same. This has the effect of remarkably improving the balance of the permeance vector in the fourth-order plane due to the unit stacking effect of the 90-degree rotation stacking of the permeance directionality of the silicon steel sheet. The permeance vector in the fourth-order plane Secondary balance effect. This effect results in low cogging torque and low vibration in motor characteristics.

Fig. 12 shows an HB type rotating electric machine with two unit rotors arranged close to each other and permanent magnets oppositely magnetized to each other, and two independent magnetic circuits in the axial direction and an unequal pitch induction. It is a figure for demonstrating the tertiary balance effect of the 4th component permeance vector of 6 inductor teeth by the structure of this invention by the combination of 90 degree rotation lamination | stacking in addition to adoption of a child tooth, and a magnetic path FIG. 6B is a diagram displaying a fourth-order plane permeance vector for each magnetic path. When increasing the lamination thickness of the stator in the axial direction with the aim of increasing torque, if the means of the present application is used, the shortened magnetic path length effect by the a and b magnetic paths divided in the axial direction and the boundary magnetic field between the two magnetic paths Using the non-interference effect, it will be explained that the rotating electrical machine is highly efficient and has little variation.
In general, the HB type stepping motor has an air gap of about 0.05 mm between the stator and the rotor. In order to secure this small air gap, the inner diameter of the stator is polished by a cylindrical grindstone called honing after the stator is laminated. However, in general, when the thickness of the stator is increased to be longer than the inner diameter of the stator, so-called taper machining is performed because of the inner diameter of the rotating grindstone or the like, for example, the inner diameter of the inner diameter is small at the beginning of machining and the inner depth of the machining is large. Easy to get up. Since the air gap is as small as 0.05 mm, even a slight gap difference appears as a permeance difference. Even in the case of the stator rotated 90 ° as described above, if the inner diameter processing is tapered, the permeance is large due to the small inner diameter in the a magnetic path in FIG. 12, and the permeance is small due to the large inner diameter in the b magnetic path. In the a and b magnetic paths, the fourth-order permeance vector is as shown in the figure. Since the unit rotors a and b are fixed on the same axis even if such a processing failure occurs, the permeance vectors of the a magnetic path and the b magnetic path are superimposed and averaged when viewed from the whole motor. Therefore, there is little variation such as cogging torque between motors. Four types of permeance vectors that can be obtained by rotating the 90 degree rotation lamination of the six permeance vectors of the fourth component of the permeance generated by the thickness and magnetic orientation of the magnetic plate of the stamped stator are also between the two magnetic paths. An increase in the degree of freedom of the additional balance effect to be balanced can also be expected. These can be called a third-order balance effect of six permeance vectors of the fourth-order component due to the two-magnetic path effect. That is, the present invention provides a rotating electrical machine having a triple balance function of the fourth harmonic permeance component.

In the prior art of FIG. 13, an expensive rare earth magnet is used for the rotor permanent magnet. According to the present invention, the same torque can be obtained with low vibration rotation by using an inexpensive ferrite magnet of the same size. That is, by dividing the magnetic circuit into two magnetic circuits in the axial direction, a low grade magnet having a residual magnetic flux density Br of 0.5 T or less, such as a ferrite magnet, can be adopted as a short magnetic circuit. For example, two ferrite magnets of the same size are cheaper than one rare earth neodymium magnet used in the prior art, so the motor cost is also low. Further, the operating point is stabilized by the flat inclination of the BH curve of the ferrite magnet, so that the motor has a low vibration due to the uniform magnetic flux density effect. This is because when the BH curve has a flat inclination, the change in the magnetic flux value can be reduced even if the operating point moves slightly due to variations in the air gap or the like.

In the motor of the present invention, the permanent magnets of the rotor are not magnetized and are magnetized after being assembled as a motor. As a magnetization method, a time difference is provided in the axial direction to perform forward direction magnetization and reverse direction magnetization. In simultaneous reverse magnetization, the magnetizing force does not reach the permanent magnet due to the repulsive magnetic flux. Referring to FIG. 2, the initial magnetization applies a magnetic field having a necessary strength from the outside of the motor for the purpose of mainly magnetizing the permanent magnet 25. Next, a magnetic field necessary to magnetize the permanent magnet 26 is partially applied. It is desirable that the magnetizing force at this time is opposite to that of the initial magnetization, and the strength thereof is appropriately adjusted from that of the first magnet to have a different strength. The two magnets can be sufficiently magnetized in directions opposite to each other by providing the time difference and arriving in the opposite directions in the axial direction and adjusting the magnetization force in the opposite direction. In this way, it is possible to provide a permanent magnet type rotating electrical machine that fully exhibits the performance of the rotating electrical machine of the present invention at low cost and with high quality.

  Since the rotating electrical machine according to the present invention stably obtains both high torque and low vibration, has high productivity and is inexpensive, a two-phase stepping motor, a two-phase AC synchronous motor, or a two-phase brushless DC motor As such, it is possible to provide an inexpensive, high-torque, low-vibration rotating electrical machine for use in a copying machine or printer that is an OA device, and a great contribution is expected industrially. In addition, application to medical equipment, FA equipment, robots, amusement machines, and housing equipment is also highly expected.

Diagram of the rotating electrical machine of the present invention Fig. 1 shows the stator and rotor of Fig. 1. Diagram of prior art stator and rotor Prior art stator diagram Illustration of vector balance according to the prior art Diagram of stator and rotor used in the present invention Principle of vector balance used in the present invention Diagram of stator phase angle relative to rotor according to the invention Explanatory drawing of the stator core used for this invention Explanatory drawing of another stator core used for this invention Explanatory drawing of balance principle of fourth permeance vector of rotating electrical machine of the present invention Explanatory diagram of the fourth permeance vector balance of the rotating electrical machine of the present invention Figure of conventional rotating electrical machine

Explanation of symbols

1: Stator 21, 22, 23, 24, 27, 28, 29, 30: Rotor
25, 26, 31, 32: Permanent magnet 3: Coil,
33: Nonmagnetic plate 4: Axes A, B, C, D, E, F, G, H: Main poles θ-θ6: Deviation angle between stator teeth and rotor teeth T1-T6: Inductor teeth,
V1 to V6: Fourth permeance vector

Claims (4)

The outer core is connected in a polygonal or annular shape including a quadrilateral, and a stator core having six inductor teeth at the tip of the main pole provided radially in the radial direction is stamped out from the magnetic plate. A permanent magnet magnetized in the axial direction by two rotors having 50 teeth provided at an equal pitch, which are rotatably provided through an air gap, by rotating and laminating by 90 degrees to form a two-phase stator. Are separated by a half pitch of the tooth pitch to form a unit rotor, and two sets of unit rotors a and b are provided close to each other on the common rotating shaft, and the unit rotors a and b The adjacent rotors have the same tooth position and are magnetized to the same polarity to form a rotor, and the two unit rotors are separated in the axial direction by the above stator via an air gap. Hybrid with two a and b magnetic paths of rotor permanent magnet flux The rotating electrical machine,
The six inductor tooth pitches provided at the tips of the eight main poles of the stator are different from the rotor tooth pitch. If the six teeth are sequentially designated as T1 to T6, the centers of the main poles are T3 and T4. When the pitch of T1 and T2 is γ, the pitch of T2 and T3 is β, and the rotor tooth pitch is c, (α + 2β + 2γ) <5c, and α ≠ β = γ. Alternatively, as unequal pitches such that α ≠ β ≠ γ, six permeance vectors in the fourth-order plane are converted into the primary in each magnetic path by the unequal pitch inductor effect in the main poles in the a and b magnetic circuits. Balance,
Furthermore, the variation of the six permeance vectors of the fourth component of the permeance caused by the thickness and magnetic direction of the magnetic plate of the stamped stator is a superposition effect of four types of permeance vectors that can be obtained by the 90 ° rotation lamination. Utilizing the shortened magnetic path length effect by the a and b magnetic paths that are secondarily balanced in the path and further divided into two in the axial direction and the magnetic field non-interference effect at the boundary between the two magnetic paths, the four kinds of permeances by the 90-degree rotation lamination A fourth-order harmonic permeance component is obtained by further superimposing six permeance vectors of the fourth-order component, which are second-order balanced by the vector superimposition effect, between the magnetic paths a and b to increase the third-order balance to enhance the balance effect. A permanent magnet type rotating electrical machine having a triple balance function. When the tooth widths corresponding to the six teeth T1 to T6 are t1 to t6, respectively, the tooth widths of the six teeth are different from each other at t1 to t3 on one side of the main polar symmetry line, and The ratio between the tooth width and the tooth pitch of each tooth, t1 / α, t2 / β, t3 / γ
The permanent magnet type rotating electric machine according to claim 1, wherein the value of is approximately 0.4. A permanent magnet type rotating electric machine according to claim 1 or 2, characterized in that the residual magnetic flux density of the permanent magnets is less ferrite system permanent magnets substantially 0.5T used in times rotor. Times rotor's permanent magnets after assembly as a motor with unpolarized, according to any one of claims 1 to 3, characterized in that with a time difference in the axial direction forward magnetization and the reverse magnetization of the permanent magnet type rotating electrical machine.

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