JP2001346372A - 2-phase hybrid type stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze the theory of vernier system which has not yet been investigated whether the pitch of the small teeth of stator should be set identical or not identical to that of the rotor in view of reducing a cogging torque of a 2-phase hybrid type stepping motor and moreover to obtain the vernier system assuring a higher degree of freedom. SOLUTION: In this 2-phase hybrid type stepping motor, the small teeth provided at the end portion of stator magnetic pole is disassembled to a desired set of two or three small teeth and the small teeth are arranged so that a sum of the fourth order and third order harmonic vectors of permeance becomes zero under the reason that a cause of generation of cogging torque lies in that permeance between small teeth respectively provided to the stator magnetic pole and rotor magnetic pole changes depending on rotation of the rotor conforming to a certain regularity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a two-phase hybrid type stepping motor, and more particularly to a two-phase hybrid type stepping motor having a stator structure capable of reducing cogging torque.

[0002]

2. Description of the Related Art One example of a conventional two-phase hybrid type stepping motor is shown in FIGS.
As shown in FIG. 1B and FIG. 1C, eight magnetic poles 2 are arranged at equal intervals on the inner circumference of the annular yoke 1, and windings 3 are wound around each of the magnetic poles 2 to form a two-phase winding. A stator 5 having a plurality of small teeth 4 provided at the tip of the magnetic pole 2 and two rotor magnetic poles 7 having a plurality of small teeth 6 provided at an equal pitch on the outer periphery thereof are arranged at a pitch of the small teeth 6. And a rotor 9 fixed to the end face of a permanent magnet 8 magnetized into two NS poles in the axial direction by shifting the rotor 9 by a half pitch. Are opposed to each other.

[0003]

A problem with this type of stepping motor is that cogging torque is generated when the winding 3 is not energized, and the output torque fluctuates to cause rotation unevenness, vibration, noise, and the like. there were.

Conventionally, in order to reduce the cogging torque, a vernier method in which the pitch of the small teeth of the stator and the small teeth of the rotor are unequal has been studied. Was not obtained. Therefore, in the present invention, it is an object of the present invention to elucidate the theory of the vernier system and obtain an effective vernier system having a higher degree of freedom.

When the equivalent magnetic circuit of the stepping motor is examined in the analysis of the present invention, FIG. 2 shows a magnetic equivalent circuit of the most general two-phase hybrid type stepping motor shown in FIGS. 1A to 1C. . FIG.
Where F _A and F _B are the magnetomotive forces of the A and B phase winding poles (hereinafter referred to as the stator poles on which the windings are wound), and Pi is the N or S pole side permeance of the i-th winding pole (here, And i is 1 to
4), F _m and P _m are the magnetomotive force and internal permeance of the magnet.

The permeances of the winding poles at the axially symmetric positions are equal to each other. In the A-phase winding, the N1 and N5 poles are connected in series in the positive direction, and the N3 and N7 poles are connected in series in the reverse direction.
Since the S pole side has the opposite relationship to the N pole side, F _A and F _B
Has the polarity shown. For example, N1 and N5 are each has with the same magnetomotive force F _A and the same permeance P _1, the magnetomotive force of the S1 and S3 on the S side of the back side of the opposite polarity -F
_A and permeance are P ₃ of opposite phase.

Referring to FIG. 2, two identical circuit groups (sub-circuits) having four branches are arranged in parallel, and two of them are arranged in series. Therefore, the equivalent circuit is replaced with one sub-circuit by circuit theory. can do. This is shown in FIG.

Here, first, the total permeance of the winding poles of the stator is examined, and the small teeth provided at the tips of the winding poles have a different pitch and face width from the small teeth of the rotor magnetic poles. Consider the cogging torque.

For a two-phase hybrid type stepping motor having ordinary eight winding magnetic poles, the general formula of torque T is as shown in Equation 1. Further, the magnetomotive force drop in the gap including the excitation (corresponding to the magnetomotive force drop between the upper and lower poles in FIG. 3) _Fo is as shown in _Expression 2. Here, the N _R number of teeth of the rotor, 2S (in the case of FIG. S = 4) number of windings poles, the theta _e is an electrical angle.

[0010]

(Equation 1)

[0011]

(Equation 2)

Each of the permeances Pi has a phase difference of 90 degrees and is represented by the following equation (3).

[0013]

(Equation 3)

Here, the outer 1 is expressed by Equation 4.

[0015]

[Outside 1]

[0016]

(Equation 4)

For example, P ₁ is as shown in Expression 5.

[0018]

(Equation 5)

The cogging torque corresponds to the case where the winding magnetomotive force is zero (F _A = F _B = 0) in equation (1). This is shown by Equations 6 and 7.

[0020]

(Equation 6)

[0021]

(Equation 7)

[0022] In order to eliminate this than the cogging torque, the sum of each order of the P _i may be accustomed to zero. Table 1 shows the respective components and their sums obtained from i = 1 to 4.

[0023]

[Table 1]

According to this, in the 8-winding pole configuration, the third and lower order cogging torques become zero, and only the fourth order component remains. This is why the fourth order component usually appears in the cogging torque. Therefore, in order to eliminate the torque, it is necessary to zero the fourth order component P _i4 of each pole permeance P _i alone.

Therefore, the permeance of each small tooth provided at the tip of the winding pole is examined, and conditions for setting the sum of the fourth order component of the permeance of each small tooth to zero are examined.

The flow of the magnetic flux differs depending on the relative positional relationship between the small teeth of the stator and the rotor. FIG. 4 shows a part of this state. Here, 2T is the repetition pitch of the rotor small teeth, α is the ratio of the stator small tooth width to the rotor tooth pitch, β is the ratio of the rotor small tooth width to the rotor small tooth pitch, and x is the center of the stator small teeth and the center of the rotor small teeth. Is the displacement associated with the rotation of Since the handling of FIG. 4 in detail is quite complicated, only the permeance of the plane (1) opposite both small teeth will be considered, taking into account the extremely small gap size. Permeance is generally calculated by equation (8).

[0027]

(Equation 8)

Here, μ ₀ is the vacuum permeability, dA is the differential facing area, and 1 is the magnetic path length. From this, the permeance P per small tooth of the winding pole can be obtained in the form of Equation 9. Where t is the core lamination thickness, w is the opposite width, l _g is the gap length.

[0029]

(Equation 9)

Since the permeance P is determined by the opposing width w of the iron core, it can be determined by knowing the movement of the opposing width between the small teeth of the stator and the small teeth of the rotor when the rotor is rotated. Since the width w changes linearly, consideration with reference to FIG. 4 reveals that the permeance P takes the form shown in FIGS. 5A and 5B.

Next, consider expressing the permeance in the form of FIGS. 5A and 5B by a Fourier series. 5A and 5
When B is generally written, it becomes as shown in FIG. Here, A and B are the height of the peak and the height of the valley, respectively, 2γ is the width of the peak, and 2δ is the width of the foot of the peak. When such an even function is represented by a Fourier series, the term of sin disappears, and the form becomes as shown in Expressions 10 and 11. Hereinafter, an angle θ is used instead of the distance x. Therefore, the period 2T = 2π.

[0032]

(Equation 10)

[0033]

[Equation 11]

When the + angle side in FIG. 6 is displayed as a function,
As shown in Equation 12, the sections can be defined separately.

[0035]

(Equation 12)

Γ, δ, A, and B in Equation 12 are shown in FIGS. 5A and 5B.
Table 2 summarizes the relationship shown in FIG. In addition,
min (α, β) is a function that takes the smaller of α and β.

[0037]

[Table 2]

In consideration of the indefinite integral formulas (13) and (14),
When the Fourier coefficients of Expression 11 are obtained, Expressions 15 to 18 are obtained.

[0039]

(Equation 13)

[0040]

[Equation 14]

Section 1

[0042]

(Equation 15)

Section 2

[0044]

(Equation 16)

[0045]

[Equation 17]

Section 3

[0047]

(Equation 18)

The sum of Equations 15 to 17 is the Fourier coefficient of the permeance change f ₁ (θ) of one small tooth, as shown in Equation 19.

[0049]

[Equation 19]

For the main torque, n = 1, and for the cogging torque, n = 4. Normal (α
+ Β) ≦ 1, Equation 18 becomes 0, Equation 15 and Equation 1
7 is the main component of the Fourier coefficient, and it can be seen that their values are determined by the tooth width ratios α and β except for the stack thickness t and the rotor tooth pitch 2T.

In summary, (1) the permeance of the small teeth is determined by the face width ratio of the rotor and the stator. (It is important that the coefficient differs depending on the tooth width.)

(2) It is difficult to achieve ΔP _i = 0 by accurately balancing the entire small teeth, because even a simplified calculation results in a complicated equation.

Accordingly, it is conceivable that a plurality of small teeth of each winding pole are used to balance between the two pairs (permeance change is set to 0).

First, the case of uniform pitch vernier will be considered. The fourth harmonic component of permeance for one small tooth is as shown in Expression 20.

[0055]

(Equation 20)

Assuming that the small teeth of the winding poles are arranged as shown in FIG. 7, in order to reduce the fourth harmonic component to zero, it is sufficient that the following expression 21 is satisfied. Here, θ _k is the position (electrical angle) of each small tooth.

[0057]

(Equation 21)

[0058] In a conventional constant pitch vernier distributed small teeth t _k is at equal tooth width at regular intervals, it is in the form of distributed unequal face width, at unequal intervals in the irregular pitch vernier. FIG. 8A shows the angular arrangement of the fourth harmonic component of the uniform pitch vernier.

In this case, it is sufficient that each vector V _k is distributed by dividing 360 degrees into six equal parts (360/6 = 60).
At this time, since any vector always has another vector at an axisymmetric position, these vectors cancel each other in pairs. Since each vector rotates while maintaining this relational position, the balance always becomes 0 even during the rotation, and Equation 22 is established. Here, m is an integer including 0.

[0060]

(Equation 22)

As an example, in the case where the number of pole pairs of teeth provided on the rotor is 50, the electrical angle of 360 degrees in the first term is equivalent to 7.2 degrees. It may be distributed every other time.

0.3 degrees is 0.3 × 50 × 4 = 60, and the facing position is 60 × 3 = 180 degrees. In an equal pitch vernier, the tooth width is usually the same, but not necessarily the same if the opposing teeth have the same width.

Next, the case of uneven pitch vernier will be considered. FIG. 8B shows an example of the vector relationship between the small teeth when the arrangement pitch of the small teeth is not equal pitch but unequal pitch.
Shown in

In the figure, V ₁ and V ₄ , V ₂ and V ₅ , V ₃ and V ₆
If we balance between the two corresponding vectors,
As a whole, P ₄ = 0 holds, and the cogging torque also becomes 0, which is shown by Expression 23. Here, Q is the number of small teeth of one winding pole.

[0065]

(Equation 23)

As long as the vectors satisfy the relationship (balance condition) that cancels out in each pair, the arrangement of each pair may be arbitrary. This is the principle of zero cogging torque. Although there are various correspondences between vectors to be balanced, the following three types are usually considered.

Assuming that the small teeth of the winding pole are arranged as shown in FIG. 7, (1) Equation 24 is obtained between adjacent small teeth.

[0068]

(Equation 24)

(2) Equation 25 is obtained between the diagonal small teeth.

[0070]

(Equation 25)

(3) Equation 26 is obtained between the small teeth symmetrical with respect to the central axis.

[0072]

(Equation 26)

Since 2mπ means the same pitch angle as the small teeth of the rotor, the deviation angle δ from the reference position is eventually obtained.
When rewritten using θ, equations 27 to 29 are obtained.

[0074]

[Equation 27]

[0075]

[Equation 28]

[0076]

(Equation 29)

The right-hand side shows a value of 0. 0 when the number of small teeth of the rotor is p = 50.
9 degrees, which is 180 degrees in the electrical angle of the fourth harmonic space.

The cogging torque elimination method for unequal pitch verniers according to this method is summarized as follows.

(1) When the number of small teeth of the rotor is p, the following equation is established.

(A) Equation 30 is obtained for the difference angle ε between the adjacent pairs t ₁ and t ₂ , t ₃ and t ₄ , and t ₅ and t ₆ .

[0081]

[Equation 30]

(B) Equation 31 is obtained for the angularly symmetric pair of t ₁ and t ₄ , t ₂ and t ₅ , and t ₃ and t ₆ .

[0083]

(Equation 31)

(C) Equation 32 is obtained for the angularly symmetric pair of t ₁ and t ₆ , t ₂ and t ₅ , and t ₃ and t ₄ .

[0085]

(Equation 32)

(2) The width of each pair of small teeth is equal to each other.

In summary, when the number of the small teeth provided at the tip of the stator magnetic pole is an even number, the small teeth are divided into two for each combination having the same tooth width. That is, the arrangement is such that the sum of the fourth harmonic vector of the permeance of each tooth of the set becomes zero.

The above examination is based on the number of small teeth provided on the winding pole.
Is made for an even number, but the number of small teeth
Considering the case where is an odd number, as shown in FIG.
In the case of an odd number, if you balance with a pair of small teeth, you will get one fraction
As a result, inconvenience may occur, so one fractional
It must be balanced with any pair of small teeth. 5
If you want to balance two and three teeth in the case of small teeth,
The vector relationship between them is as shown in FIG. here
Is V₁, V_Three, V_FiveBetween three vectors and V_Two, V _Four2
Each has a balance between the vectors. In this case, the corner
Degree δθ₁, Δθ_Three, Δθ_Five, And δθ_Two, Δθ_FourRose in
Relationship.

Table 3 shows the results of an investigation on what kind of motor is actually used based on the above theory.
A, B, and C are practically used, C is of equal pitch, and trial calculations 1, 2, and 3 are trial calculation examples based on the above theory. The unit is the mechanical angle °.

[0090]

[Table 3]

In Table 3, ○ indicates the evaluation of balance, and the example of trial calculation 3 satisfies three types of arrangement conditions, the trial calculation 2 satisfies two types of arrangement conditions, and the trial calculation 1 and the C motor satisfies one type of arrangement condition. To be satisfied. When these are represented by vectors in the fourth harmonic electrical angle space, they are as shown in FIGS. 11A to 11C. FIG.
In FIG. 1A and FIG. 11B, since there is a vector having a different size in the opposing vector, it can be seen that the fourth harmonic component remains without being canceled out. In the case of trial calculation examples 2 and 3, FIG.
All vector is in the form of concentrates in the direction of V ₂ and V ₅ as shown in C. Compared to a uniform pitch vernier (FIG. 8A)
Since this method has a high degree of freedom in angle arrangement, there is an advantage that the angle can be set in detail in consideration of the influence on other harmonics.

In addition, a method of eliminating both the third harmonic and the fourth harmonic will be discussed. The A-phase winding of the two-phase motor forms a circuit in which the windings of the first and third magnetic poles are connected in series with opposite polarities, and the B-phase winding similarly has the second and fourth magnetic poles. To form an inverse series circuit. Therefore, in the A phase, the effects of the two windings are differentially added, and in the B phase, the same effects are differentially added to generate a linkage magnetic flux. Looking at the relationship between the Fourier coefficients of each harmonic from Table 1, in the case of differential, even-order harmonics are canceled by both.
It can be seen that odd harmonics are added. The first harmonic generates an induced voltage corresponding to the main torque of the sine wave,
Since the third harmonic causes unnecessary distortion, it is necessary to remove the third harmonic. Hereinafter, a method of minimizing the third harmonic while balancing the fourth harmonic will be considered.

Vector diagrams in the fourth harmonic space for the arrangement of the small teeth in the equal pitch vernier system and the unequal pitch vernier system according to the prior art are shown in FIG. 8A and FIG.
B, which is drawn in the third harmonic front, as shown in FIG.
2. As shown in FIG.

In FIG. 12, vectors V ₁ , V ₄ and V
Each angle between ₂ and V ₅ , V ₃ and V ₆ is 180 degrees, 3/4 = 1
35 degrees, and when there are six small teeth of the winding pole, the vectors having a 180 degree relationship with each other in the fourth harmonic space are 3
Exist. Two vectors 180 degrees apart in the fourth harmonic space become two vectors 135 degrees apart in the third harmonic space. In order for these three pairs to be balanced in the fourth harmonic space, it is necessary that the combined vectors be separated by 120 degrees and the total vector sum be zero.

The following is a summary of the above conditions.

(1) The difference angle ε between the pair of small teeth is expressed by the following equation.
45 ° / p (0.9 ° for 50 teeth) shown in Expression 32.

(2) The center angle of the pair vector is γ = 40
° / p (0.8 ° for 50 teeth).

FIG. 14 can be considered as a solution to the above conditions. This means that the deviations from the three vectors (dotted lines) balanced in the third harmonic plane are + 4.5 ° and -4.5 in mechanical angles.
°. (Trial calculation example 4 in Table 4) The shape of the small teeth in this case is shown in FIG.

When the deviation is larger than the reference angle, the fundamental wave component contributing to the torque is reduced. Therefore, it is conceivable to slightly reduce the deviation angle at the expense of the third harmonic distortion.
Table 4 also shows a trial calculation example taking these factors into consideration.

[0100]

[Table 4]

Also, in the case where the number of small teeth of one winding pole is an odd number, the combined vector of the set of three small teeth and the set of two small teeth balanced in the fourth harmonic space is also used. Is the third
By arranging the small teeth so as to be balanced in the second harmonic space, it is possible to simultaneously minimize cogging torque and minimize main torque distortion.

In Table 4, .largecircle. Indicates that the balance is good, and .DELTA. Indicates the next best. FIG. 16A and FIG. 16B show the arrangement of the vectors and the small teeth in the trial calculation example 6.

FIGS. 17A and 17B show vector balances in the third and fourth harmonic spaces when the number of small teeth is 7 (odd number). FIG. 17C shows the small tooth arrangement. Here, the vectors V ₁ and V ₃ , V ₅ and V ₇ and V ₂ , V ₄ and V _{6 form a} set, and the vectors of the fourth harmonic space are balanced in each set, and the combination of each set is performed. The vectors V ₁₃ , V ₅₇ and V ₂₄₆ are balanced in the third harmonic space. Incidentally, since the larger the width of t _4, which results in subtle changes in the angle of each vector.

As a result of the above examination, it has been found that the unequal pitch vernier method is effective for reducing the cogging torque of the two-phase stepping motor. As a means to realize it

(1) The width of the small teeth affects the magnitude of the fourth harmonic of the permeance.

(2) As a new unequal pitch vernier method, a method of balancing with a set of two or three small teeth has a large degree of freedom.

[0107]

In the present invention, the cause of the cogging torque is determined by the fact that the permeance between the small teeth provided on each of the stator magnetic pole and the rotor magnetic pole changes with the rotation of the rotor. Thinking that the change is due to regularity,
Arrangement of small teeth provided at the tip of the stator magnetic pole
The problem is solved by decomposing the set into individual or three sets of small teeth and arranging them so that the sum of the fourth harmonic vector of permeance becomes 0 in each set.

In the two-phase hybrid type stepping motor of the present invention, a plurality of magnetic poles are arranged at equal intervals on the inner periphery of a substantially annular yoke, and a winding is wound around each of the magnetic poles to form a two-phase winding. And a stator provided with an even number of at least four small teeth at the tip of the magnetic pole, and two rotor magnetic poles provided with a plurality of small teeth at an equal pitch on the outer periphery of the stator. A two-phase hybrid type comprising a rotor fixed to the end face of a permanent magnet magnetized in the axial direction by NS two poles shifted by a half pitch of the arrangement pitch, wherein the rotor faces the stator via a gap. In the stepping motor, the small teeth provided at the tip of the stator magnetic pole are constituted by a set of two small teeth having the same tooth width, and the fourth harmonic vector of the permeance of the small teeth included in each set. At least one such that the sum is substantially zero The pitch of an adjacent small tooth is different from the pitch of another adjacent small tooth.

In the two-phase hybrid type stepping motor of the present invention, a plurality of magnetic poles are arranged at equal intervals on the inner periphery of a substantially annular yoke, and a winding is wound around each of the magnetic poles. And at the tip of the pole an odd number of at least 5
A stator provided with a plurality of small teeth and two rotor magnetic poles provided with a plurality of small teeth on an outer periphery thereof at an equal pitch are shifted from each other by a half pitch of the arrangement pitch of the small teeth, so that the axial direction A two-phase hybrid type stepping motor comprising a rotor fixed to an end face of a permanent magnet magnetized with two NS poles, and the rotor being opposed to a stator via an air gap. The teeth are divided into three sets including the centrally located small teeth and two other sets having the same tooth width, and the fourth harmonic vector sum of the permeance of the small teeth included in each set. The pitch of at least one adjacent small tooth is made different from the pitch of another adjacent small tooth so that is substantially zero.

The two-phase hybrid type stepping motor according to the present invention has a plurality of magnetic poles arranged at equal intervals on the inner periphery of a substantially annular yoke, and a winding is wound around each of the magnetic poles. And an even number of at least 4 at the tip of the pole.
A stator provided with a plurality of small teeth and two rotor magnetic poles provided with a plurality of small teeth on the outer periphery thereof at an equal pitch are shifted in the axial direction by ピ ッ チ pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor, comprising a rotor fixed to an end face of a permanent magnet magnetized with NS2 poles, the rotor being opposed to the stator via an air gap; The tooth is constituted by a set of two small teeth whose tooth widths are equal to each other, and the sum of the fourth harmonic vector of the permeance of the small teeth included in each set becomes substantially zero, and the permeance of each set is synthesized. The pitch of at least one adjacent small tooth is different from the pitch of another adjacent small tooth so that the third harmonic vector sum of the vector is substantially zero.

Further, the two-phase hybrid type stepping motor of the present invention has a plurality of magnetic poles arranged at equal intervals on the inner periphery of a substantially annular yoke, and a winding is wound around each of the magnetic poles. And an odd number of at least 5 at the tip of the pole.
A stator provided with a plurality of small teeth and two rotor magnetic poles provided with a plurality of small teeth on the outer periphery thereof at an equal pitch are shifted in the axial direction by ピ ッ チ pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor, comprising a rotor fixed to an end face of a permanent magnet magnetized with NS2 poles, the rotor being opposed to the stator via an air gap; The tooth is constituted by a set of three small teeth and another set of two small teeth whose widths are equal to each other, and the fourth harmonic vector sum of the permeance of the small teeth included in each set is substantially equal. And the pitch of at least one adjacent small tooth is made different from the pitch of other adjacent small teeth so that the sum of the synthesized vector of each set of permeances in the third harmonic space is substantially zero. It is characterized by the following.

[0112]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, a two-phase hybrid type stepping motor is provided by arranging a plurality of magnetic poles 2 at equal intervals on the inner circumference of a substantially annular yoke 1, and winding a winding 3 around each of the magnetic poles 2. A stator 5 which forms a two-phase winding and has four small teeth 4 provided at the tip of the magnetic pole 2 and two rotor magnetic poles 7 provided with a plurality of small teeth 6 at an equal pitch on the outer periphery thereof And a rotor 9 fixed to the end face of a permanent magnet 8 magnetized in the NS direction by shifting the pitch of the small teeth 6 by １ ／ of the arrangement pitch of the small teeth 6, so that the rotor 9 is rotatable. The four small teeth 4 which are axially supported, face the stator 5 via a gap, and are provided at the tip of the stator magnetic pole 2 are constituted by a set of two small teeth 4 having the same tooth width. , At least so that the fourth harmonic vector sum of the permeance of the small teeth included in each set becomes substantially zero. One pitch between adjacent teeth made different to the pitch of another adjacent teeth. The number of the small teeth 4 of the stator magnetic pole 2 can be 6, 8, 10, or 12.

In another embodiment of the present invention, a two-phase hybrid type stepping motor has a plurality of magnetic poles 2 arranged at equal intervals on the inner periphery of a substantially annular yoke 1, and a winding 3 is attached to each of the magnetic poles 2. A stator 5 having a two-phase winding formed by winding and having five small teeth 4 provided at the tip of the magnetic pole, and two rotations having a plurality of small teeth 6 provided at an equal pitch on the outer periphery thereof. The magnetic pole 7 is shifted in the axial direction by half the pitch of the small teeth, and
Rotor 9 fixed to end face of permanent magnet 8 having magnetized S2 pole
The rotor 9 is rotatably supported, is opposed to the stator 5 via a gap, and the small teeth 4 provided at the tip of the stator magnetic pole 2 are replaced with the small teeth 4 located at the center. And at least one adjacent small tooth such that the sum of the fourth harmonic vector of the permeance of the small teeth 4 included in each of the three sets is substantially zero. Is different from the pitch of other adjacent small teeth. Stator magnetic pole 2
Of small teeth 4 can be 7, 9, 11, or 13.

In still another embodiment of the present invention, a two-phase hybrid type stepping motor is provided with a substantially annular yoke 1.
A plurality of magnetic poles 2 are arranged at equal intervals on the inner periphery of the magnetic pole, and a winding 3 is wound around each of the magnetic poles 2 to form a two-phase winding.
A stator 5 provided with four small teeth 4 at the tip of the rotor, and two rotor magnetic poles 7 provided with a plurality of small teeth 6 at an equal pitch on the outer periphery thereof.
Is shifted by １ ／ of the arrangement pitch of the small teeth 6,
A rotor 9 fixed to an end face of a permanent magnet 8 magnetized with two NS poles in the axial direction, rotatably supporting the rotor 9, facing the stator 5 via a gap, and The small teeth 4 provided at the tip of the daughter magnetic pole 2 are classified into two sets of small teeth having the same tooth width, and the fourth harmonic vector sum of the permeance of the small teeth included in each set is substantially equal. The pitch of at least one adjacent small tooth is made different from the pitch of another adjacent small tooth so that the third harmonic vector sum of each set of permeances becomes substantially zero and is substantially zero.

In still another embodiment of the present invention, a two-phase hybrid type stepping motor is provided with a substantially annular yoke 1.
A plurality of magnetic poles 2 are arranged at equal intervals on the inner periphery of the magnetic pole, and a winding 3 is wound around each of the magnetic poles 2 to form a two-phase winding.
A stator 5 having five small teeth 4 at the tip of the rotor, and two rotor magnetic poles 7 having a plurality of small teeth 6 provided at an equal pitch on the outer periphery thereof.
Is shifted by １ ／ of the arrangement pitch of the small teeth 6,
A rotor 9 fixed to an end face of a permanent magnet 8 magnetized with two NS poles in the axial direction, rotatably supporting the rotor 9, facing the stator 5 via a gap, and The small teeth 4 provided at the tip of the secondary magnetic pole 2 are divided into a set of three small teeth having the same tooth width and two teeth having the same tooth width.
And the sum of the fourth harmonic vector of the permeance of the small teeth included in each set is substantially zero, and the sum of the third harmonic vector of the permeance of each set is substantially zero. The pitch of at least one adjacent small tooth is made different from the pitch of another adjacent small tooth so that the pitch becomes zero.

[0117]

Since the two-phase hybrid stepping motor according to the present invention has the above-described structure, a plurality of small teeth provided at the tip of the stator magnetic pole on which the winding is wound are arranged at an irregular pitch. According to the vernier method, there is a great advantage that the cogging torque can be reduced by reducing the fourth and third harmonic magnetic fluxes, thereby reducing vibration and noise.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional front view of a conventional two-phase hybrid type stepping motor.

FIG. 1B is a left side view (N pole side) of a conventional two-phase hybrid type stepping motor.

FIG. 1C is a right side view (S pole side) of a conventional two-phase hybrid type stepping motor.

FIG. 2 is an equivalent magnetic circuit diagram of a two-phase eight-winding-pole hybrid type stepping motor.

FIG. 3 is an equivalent magnetic circuit diagram showing the circuit of FIG. 2 with one sub-circuit;

FIG. 4 is a diagram showing a virtual magnetic path between magnetic poles in which respective small teeth of a stator and a rotor face each other.

5A is a diagram showing a change in permeance between virtual magnetic poles in FIG. 4;

FIG. 5B is a diagram showing a change in permeance between virtual magnetic poles in FIG. 4;

FIG. 6 is a diagram showing a general form of the permeance change shown in FIGS. 5A and 5B.

FIG. 7 is a diagram showing an arrangement of small teeth of a winding pole;

FIG. 8A is a vector diagram showing a balance of permeance vectors for an equal pitch vernier on a fourth harmonic electrical angle plane.

FIG. 8B is a vector diagram showing a balance about unequal-pitch verniers in the fourth-harmonic electrical angle plane.

FIG. 9 is a diagram showing an example of the arrangement of small teeth when the number of small teeth is five.

FIG. 10 is a vector diagram showing a permeance vector balance for an odd number of small teeth.

FIG. 11A is an arrangement example of unequal-pitch verniers in the fourth harmonic electric angle plane of the A motor.

FIG. 11B is an example of the arrangement of unequal pitch verniers on the fourth harmonic electric angle plane of the B motor.

FIG. 11C is an arrangement example of unequal-pitch verniers on the fourth-harmonic electrical angle plane in Trial Calculation Example 1.

FIG. 12 is a diagram of a third harmonic vector in an equal pitch vernier.

FIG. 13 is a diagram of a third harmonic vector in an irregular pitch vernier.

FIG. 14 is a vector diagram showing a balance state in a third harmonic space.

FIG. 15 is a diagram showing an example of the arrangement of small teeth in which the third and fourth harmonics are balanced.

FIG. 16A is a diagram showing the angular relationship of each vector on the third harmonic plane in Trial Calculation Example 3;

FIG. 16B is a diagram showing an example of the arrangement of small teeth in a third example of calculation.

FIG. 17A is a diagram showing the angular relationship of each vector on the third harmonic plane when the number of small teeth is seven.

FIG. 17B is a diagram showing the angular relationship of each vector on the fourth harmonic plane when the number of small teeth is seven.

FIG. 17C is a diagram showing an arrangement of small teeth corresponding to FIGS. 17A and 17B.

[Explanation of symbols]

Phase F _A phase B stator A stator Makisenkyoku A, magnetomotive force F _B of the B phase winding pole Makisenkyoku A, B of the phase winding pole magnetomotive force F _m magnetomotive force of the magnet and the internal permeance P _m Magnet Magnetomotive Force and Internal Permeance P _i Permeance between a plurality of small teeth of i-th winding pole and small teeth of rotor N _R Number of teeth of rotor F ₀ Magnetomotive force drop including void excitation 2S winding Number of poles θ _e Electrical angle ζ _i Angle including phase difference of i-th winding pole T _C Cogging torque 2T Repetition pitch of rotor small teeth α Ratio of stator small tooth width to rotor small tooth pitch β Rotor Ratio of small tooth width to rotor small tooth pitch x Displacement due to rotation of stator small tooth center and rotor small tooth center V _k Permeance vector of kth small tooth δθ Deviation angle t of stator small tooth from reference position t ₁ small teeth t ₅ of the small teeth t ₄ stator poles of teeth t ₃ the stator magnetic pole of the teeth t ₂ stator poles of the stator pole Resultant vector of vectors constituting the angle γ pairs between vectors constituting the stator (teeth number of the rotor) teeth p pole logarithm of small teeth t ₇ the stator magnetic pole of the teeth t ₆ stator poles of the magnetic pole ε pairs Angle between 1 Toroidal yoke 2 Magnetic pole 3 Winding 4 Small teeth 5 Stator 6 Small teeth 7 Rotor magnetic pole 8 Permanent magnet 9 Rotor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroki Isozaki 3-93 Aioimachi, Kiryu-shi, Gunma F-term in Kiryu Plant of Serbo Japan (reference) 5H002 AA01 AE07

Claims (4)

[Claims] A plurality of magnetic poles are arranged at equal intervals on the inner circumference of a substantially annular yoke, windings are wound around each of the magnetic poles to form a two-phase winding, and an even number is provided at the tip of the magnetic pole. The stator provided with at least four small teeth and the two rotor magnetic poles provided with a plurality of small teeth at an equal pitch on the outer periphery thereof are shifted by a half pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor comprising: a rotor fixed to an end face of a permanent magnet magnetized to NS2 poles in the axial direction, wherein the rotor is opposed to the stator via a gap. The small teeth provided at the tip are constituted by a set of two small teeth whose tooth widths are equal to each other, and the fourth harmonic vector sum of the permeance of the small teeth included in each set is substantially zero. The pitch of at least one adjacent tooth is different from the pitch of another adjacent tooth. 2-phase hybrid stepping motor, characterized in that had RaShime. 2. A two-phase winding is formed by arranging a plurality of magnetic poles at equal intervals on the inner periphery of a substantially annular yoke, winding a winding around each of the magnetic poles, and forming an odd number The stator provided with at least five small teeth and the two rotor magnetic poles provided with a plurality of small teeth at an equal pitch on the outer periphery thereof are shifted by a half pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor comprising a rotor fixed to an end face of a permanent magnet magnetized with two NS poles in the axial direction, wherein the rotor faces the stator via a gap. Are divided into three sets including the centrally located small teeth and two other sets having the same tooth width, and the fourth order of the permeance of the small teeth included in each set is divided into three sets. The pitch of at least one adjacent small tooth is adjusted so that the harmonic vector sum is substantially zero. 2-phase hybrid stepping motor, characterized in that it made different pitch of the small teeth in contact. 3. A plurality of magnetic poles are arranged at equal intervals on an inner periphery of a substantially annular yoke, and a winding is wound around each of the magnetic poles to form a two-phase winding. The stator provided with at least four small teeth and the two rotor magnetic poles provided with a plurality of small teeth on the outer periphery thereof at equal pitches are shifted by a half pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor comprising: a rotor fixed to an end face of a permanent magnet magnetized with two NS poles in the axial direction, wherein the rotor is opposed to the stator via an air gap. Are formed by a set of two small teeth whose tooth widths are equal to each other, and the fourth harmonic vector sum of the permeance of the small teeth included in each set becomes substantially zero, and And the third harmonic vector sum of the resultant vector of permeance is substantially zero A two-phase hybrid type stepping motor, wherein a pitch of at least one adjacent small tooth is made different from a pitch of another adjacent small tooth. 4. A two-phase winding is formed by arranging a plurality of magnetic poles at equal intervals on the inner periphery of a substantially annular yoke, winding a winding around each of the magnetic poles, and forming an odd number at the tip of the magnetic pole. The stator provided with at least five small teeth and the two rotor magnetic poles provided with a plurality of small teeth at an equal pitch on the outer periphery thereof are shifted by a half pitch of the arrangement pitch of the small teeth. A two-phase hybrid type stepping motor comprising: a rotor fixed to an end face of a permanent magnet magnetized with two NS poles in the axial direction, wherein the rotor is opposed to the stator via an air gap. Is constituted by a set of three small teeth and another set of two small teeth having the same tooth width, and the fourth harmonic vector of the permeance of the small teeth included in each set. The sum is substantially zero, and the third harmonic space of the resultant vector of each set of permeances Wherein the pitch of at least one adjacent small tooth is made different from the pitch of another adjacent small tooth so that the sum of the two is substantially zero.