JPH03285542A - Squirrel-cage rotor - Google Patents

Abstract

PURPOSE:To manufacture a laminated core easily at a low cost by asymmetrically forming the punched part of steel plates so that the bridged part or the opening at the outer circumferential side is shifted by a predetermined distance to one side from the center line of a main part where a conductor is contained. CONSTITUTION:A unit block 4 of a laminated core 1 is formed by laminating a plurality of steel plates 3 having a punched part 2 at same position so that protrusions 3a, inflated or rised to the inner circumferential side, are overlapped. A slot 5 is formed in parallel with the axis of a rotary shaft and a bridge part or an opening 5b is formed at a position shifted by a predetermined distance (d) from the center line l of a main part 5a. Rotor diameter D, corresponding number of slot Z in the stator and the number of pole pair (p) satisfy a relation piD/4(Z+p)<=d<=piD/4(Z-p).

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a cage-shaped core having a laminated iron core formed by laminating steel plates each having a plurality of slot forming portions for accommodating conductors formed on the outer periphery thereof. Regarding the rotor.

(Prior Art) In general, this type of squirrel cage rotor has a laminated core formed by laminating a large number of magnetic steel plates each having a plurality of slots formed in advance by punching or the like on the outer periphery. A squirrel-cage conductor is formed by forming a secondary conductor made of aluminum or the like in the slot by a method such as casting, and connecting the ends of the secondary conductor with an end ring.

In this case, when the rotor is driven, the magnetic flux that enters the laminated core from the stator through the gap contains harmonic components, and the harmonic components of this magnetic flux cause the secondary conductor to This will generate harmonic electromotive force. However, such harmonic electromotive force acts on the rotor as abnormal torque, resulting in pulsating torque and causing vibration or noise.

Therefore, in order to suppress the adverse effects of such harmonic components, a laminated iron core in which the rotor is so-called skewed has been conventionally used. This is a technique in which the positions of the rotor slots are slightly shifted in the circumferential direction when the steel plates are laminated; for example, there is one in which the positions of the rotor slots are shifted by one pitch of the stator slots as a whole. By doing this, the phase of the electromotive force generated in the secondary conductor is slightly shifted based on the harmonic component of the magnetic flux, so the harmonic component of the overall electromotive force is canceled out, and the amount that contributes to the abnormal torque is canceled out. is suppressed.

(Problems to be Solved by the Invention) However, the conventional configuration as described above had the following problems.

In other words, when laminating steel plates while skewing them, a special jig is required to adjust the pitch, and it takes a lot of time to adjust (especially when the slot is fully open, the laminated In this case, the position of the slot cannot be seen from the outer circumferential direction, which is time-consuming), which inevitably increases costs. In addition, when skewing in this way, the skew effect will be significantly reduced if the skew amount is not set appropriately, but since the appropriate skew amount has not been theoretically established, In order to determine the amount of skew, it is necessary to make a prototype, so there is a problem that a large amount of cost is incurred.

In order to solve such problems that occur in the rotor, for example, as shown in Japanese Patent Application Laid-Open No. 64-81647, a rod-shaped secondary conductor is directly press-fitted into the slot without forming the secondary conductor by casting. There is something I did. In other words,
In this case, a slot is formed without skewing and the secondary conductor is housed by press-fitting. In this case, since no skew is applied to the laminated core of the rotor, the solution to the problem caused by the harmonic components mentioned above is to make the core of the stator skin skinny so that the harmonic components of the magnetic flux do not enter the rotor. That's how I do it. Therefore, it takes time and effort to store the windings and insulators in the slots of the stator, which reduces the efficiency of assembly work and, in particular, makes automatic mounting impossible, resulting in a large cost increase.

Further, in order to solve the above-mentioned problems, it has been considered to obtain only a skew effect without skewing the laminated core of the rotor when laminating steel plates. For example, in the one shown in Japanese Utility Model Publication No. 52-17045, the portion corresponding to the opening or bridge portion of the slot is offset from the center line of the slot. However, even in this case, when stacking the steel plates, it is necessary to align the slots so that they match, and in particular, when the slots are completely closed, it is necessary to use a special jig to hold the stacked steel plates. The assembly process required a lot of effort and time as the parts were being formed at the same time.

The present invention was made in view of the above circumstances, and its purpose is to easily and inexpensively produce a laminated iron core without making steel plates skinny or using special jigs for lamination. It is an object of the present invention to provide a squirrel cage rotor that can suppress abnormal torque, vibration, or noise in the same way as a skewed rotor.

C Structure of the Invention] (Means for Solving the Problems) The present invention forms a laminated iron core by laminating a predetermined number of steel plates each having a punched part for forming a slot for accommodating a conductor in the outer periphery. The target is a squirrel-cage rotor, in which the steel plate is provided with a protruding part formed by bulging or cutting, and the punched part of the steel plate is provided with a bridge part or an opening on the outer peripheral side of the steel plate. The laminated core is formed into an asymmetrical shape that is shifted by a distance d that satisfies the following condition on one side with respect to the center line of the main part in which the conductor is housed, and the laminated core is formed in such a way that the steel plate is aligned with the direction and position of the slot. A plurality of stacked unit blocks are combined so that the protrusions overlap in a matched state, and the slots in each unit block have different directions and the main parts overlap. Characteristics.

However, D: Rotor diameter 2: Number of slots in the corresponding stator p: Number of pole pairs Also, the distance between the punched parts of the steel plate for forming the slots is approximately the same size up to the outer periphery of the steel plate. It is preferable to form it in an asymmetrical state in this way.

(Function) According to the squirrel cage rotor of the present invention, as shown in FIG. A unit block 4 is formed by laminating a plurality of unit blocks 4 at the same position so that the protrusions 3a overlap, and a plurality of unit blocks 4 (the figure shows the case of two unit blocks 4A and 4B) are combined to form a unit block 4. ing. The slot 5 is formed parallel to the axis of the rotating shaft, and has a bridge portion or opening 5b with respect to its main portion 5a.
(The figure shows a case where the slot 5 is completely closed and the outer peripheral side becomes the bridge part 5b) is a predetermined distance from the center line p of the main part 5a, l! They are formed at positions shifted by Id, and are arranged so that the direction of shift is opposite for each unit block 49.4B.

As mentioned above, each unit block 4^+4B is made of steel plate 3
By stacking them so that their protruding parts 3a overlap,
As shown in the cross section in FIG. 2, the alignment is automatically performed, so the main parts 5a of the slots 5 are arranged so as to overlap without using a special jig, etc., and the state is maintained by the jig etc. It can be held without being fixed, and the laminated core 1 can be formed easily and quickly. In addition, by forming the laminated core 1 without skinny, the protruding portion 3 of the steel plate 3
Since it is sufficient to form the parts a at the same position, the manufacturing cost of the steel plate 3 does not increase significantly.

As for the electrical characteristics, based on the principle shown below, the same effect as in the case of skew can be obtained, and abnormal torque generation and vibration due to the drive of the rotor can be obtained.

This makes it possible to suppress noise as much as possible.

That is, as shown in FIG. 3, the magnetic fluxes Φ and Φ3 entering the unit blocks 4A and 4B from the stator side through the gap have different inflow paths, resulting in a phase difference α (electrical angle). If the voltages induced in the secondary conductor 6 housed in the slot 5 by the magnetic fluxes Φ9 and Φ8 are respectively eA and es, a phase difference αb is also generated. This is caused by a distance 2d corresponding to the difference in path, and specifically, it is given by the number of pole pairs p and the pole pitch τ expressed by the outer diameter of the laminated core 1 as shown in the following equation.

2dπ α = ... (1> Ship On the other hand, the induced voltages eA and e8 are each expressed as vector quantities as shown in Fig. 4, and the voltage e actually generated in the secondary conductor 6 is It is a value expressed as the sum e-eA+e[l. The magnetic fluxes Φ6 and Φ8 contain harmonic components, and thereby the induced voltages eA and eR also have harmonic components.

However, since there is a phase difference α between the two, the degree of the harmonic component included in the induced voltage e, which is the combined value of these, becomes a different value depending on each order.

A skew coefficient Ksn indicating the degree of harmonic components included in such an induced voltage e is given by the following equation.

Now, if we assume that the unit blocks 4A and 4m have the same thickness, 1eAf-! esl, and as conceptually shown as a vector in FIG. 4, the value of the denominator in equation (2) is equal to twice the length 2r of the line segment OA.

Further, the magnitude of the vector sum in the numerator of the open equation is equal to the length q of the line segment OB in the figure. When these values are expressed in accordance with equation (2), they are calculated as follows.

Also, in the 0th harmonic, the phase angle α is n times larger, so a is set to nff1. :I In other words, the skew coefficient Ksn of equation (2) can be expressed as follows.

Now, it is generally well known that harmonics that tend to generate abnormal torque, vibration, or noise are groove harmonics caused by stator slots, and the order μ of the harmonics is It is expressed as follows.

μ glue = −± 1 (5) (However, 2 is the number of stator slots) Therefore, the value of the skinny coefficient Ksn in the case of the present invention at the order shown in the above formula (5) is given by the formula ( 4) is calculated as follows. That is, first, for the range (A) of the set distance d, the range of the phase difference α is calculated from equation (1) as follows: πP KP ≦ α ≦ 2+ρ χ+ρ (6) Based on this result, the range of phase difference α is calculated as follows: Skew coefficient K shown in (4)
First, let us find the first order (n-1) case of sn. , if the decoding of the numerator and denominator has the same sign, Ksn=
COm = Q ...(9) (b), with the upper limit of α, ...wcos (correct 1 ...(7b)) Here, in the general case, the number of slots in the stator is 2. Since it is larger than the logarithm p (for PJ, z-48, p-2
), the values of equations (7a) and (7b) are approximately 1.

On the other hand, the skew coefficient Kgn due to the 88th harmonic shown in equation (5) is always zero at the upper limit and below the distance fid. In addition, in the case of opposite signs, as described above, considering the general case where the number of stator slots 2 is larger than the number of pole pairs p, Ksn # cos () = 0 ... (10), The eighth factor that has a negative effect on the rotor shown in equation (5)
The fifth-order skew coefficient Ksn can be set to approximately zero. Therefore, in any case, the skew coefficient can be set to approximately 1 for the first-order component of the voltage induced in the conductor, which effectively acts as the rotational force of the rotor.
The induced voltage of the μs-order harmonic component, which causes abnormal torque, vibration, or noise, can be reduced as much as possible, and the same effect as when skewing is achieved can be obtained.

Incidentally, FIG. 5 shows the results of calculating the skew coefficients derived in this way according to certain conditions.

In this case, the coefficient values obtained when conventional skewing is performed are also shown, and the skinny coefficient Kns' is given by the following equation.

As can be seen from this result, when conventional skewing is performed, the value of distance d becomes a large value of 0.6 or more even in the range of formula (A), whereas in the case of the present invention, The value is less than or near 0.1, and a sufficiently large skinny effect is obtained.

In addition, when using the above-mentioned steel plate 3, if the distance between the slots 5 formed by the punched parts 2 is narrow at the outer periphery (see Fig. 1), the distance S between the slots should be By forming the shoulder portion 3b so that it is approximately equal to the width k, the magnetic flux is prevented from being concentrated at the shoulder portion 3b and the magnetic flux density becomes large. As a result, even if the slot-forming portion of the steel plate 3 is processed as described above, no area with high magnetic flux density will be created.

(Embodiment) Hereinafter, a first embodiment in which the present invention is applied to a motor will be described with reference to FIGS. 6 to 10.

First, in FIG. 9 showing the overall configuration in cross section, the stator 1
1 consists of a stator core 12 and a fixed pre-winding 1113 housed in a slot (not shown). The stator core 12 is formed by stacking steel plates 14 with punched slot portions without skewing. There is.

The squirrel-cage rotor 15 consists of a rotating shaft 16 supported by a bearing (not shown) and a laminated core 17 fitted onto the rotating shaft 16. The laminated core 17 has a number of slots 18 formed along its outer periphery. ing.

A secondary conductor 19 is press-fitted into the slot 18 of the laminated core 17, and an end ring 20 is fixed to connect the ends of the secondary conductor 19 to form a squirrel-cage conductor 21.

Next, the squirrel cage rotor 15 will be described in detail.

The steel plate 22 constituting the laminated core 17 is a silicon steel plate.

It is made of a magnetic plate such as a cold-rolled steel plate or an amorphous magnetic material, and has a disk shape with an outer diameter of D. As shown in FIG. A large number of punched portions 23 are formed. This punching part 23 is
The main portion 23a and the bridge portion 23b for generating a skew effect are arranged in the following relationship. That is, the position of the bridge portion 23b is at the center of the main portion 23g! ! It is arranged to be shifted to one side by a predetermined distance d with respect to 1g. The distance Md is set as follows, as a value that satisfies the condition shown in equation (A) above.

z Also, on the inner circumferential side of the steel plate 22, as shown in an enlarged view in FIG. There is. The cut and raised portions 24b are formed at, for example, four locations as shown in FIG. 8, and in the stacked state, as shown in FIG. It does not require any special skills and can be laminated easily and quickly. Moreover, the formation position of the protrusion 24 is as follows.
Since no skew is performed, there is no misalignment with respect to the steel plate 22, so it is sufficient to manufacture the same one, and it can be manufactured at low cost using a simple cutting die.

Then, a predetermined number of such steel plates 22 are delivered at the same position (in other words, without being skinny) to obtain a thickness of 1/2 of the total thickness L.
A unit block 25 with a thickness of The laminated iron core 17 is configured by combining them (see FIG. 9). Therefore, when the slots 18 of the laminated core 17 are viewed in the axial direction of the rotating shaft 16, the positional relationship between each slot 18 is such that the position of the bridge portion 23b is shifted by a distance of 2d between the unit blocks 25 and 26 (
(See Figure 3).

According to the squirrel cage rotor 15 formed in this way, the following skinny effect can be obtained in the rotating state.

That is, in this embodiment, the distance d described above is expressed as
Since the settings are as shown in the following, the value of the phase difference α corresponding to equation (6) is πp α = □ (b). Therefore, the skew coefficient Ksn is expressed by the formula (7a),
The following values are obtained corresponding to (7b) and equation (8).

(a) First-order case (n-1) (b) μ Third-order case [μ5-(z/p)±1] For example, let us assume that the number of slots 2 in the stator is 36 and the number of pole pairs p is 2.
When calculated as shown in FIG. As a result, the value of the skew coefficient Ksn in equation (c) is 0.99
6, so it can be considered approximately 1, and the value of the skinny coefficient Ksn in equation (d) is 0.087 for both the 17th and 19th orders.
Therefore, it can be regarded as approximately zero. Therefore, when comparing the skinny coefficients Ksn and Ksn' between the conventional method and this embodiment, it is found that 1
For the 7th and 19th orders, the improvement in this example is from 13% to 15% in the conventional case.
%. Therefore, harmonic torque is reduced, so the occurrence of abnormal torque is suppressed as much as possible, and vibration and
Noise generation is also reduced.

11 to 13 show a second embodiment of the present invention, and only the parts different from the first embodiment will be described below.

That is, in this second embodiment, a laminated iron core 17' is formed using a steel plate 22' instead of the steel plate 22, and the shape of the steel plate 22' is shown in FIG. The shape of the punched part 23' formed in the steel plate 22' is a shoulder part 23c located on the outer peripheral side on the opposite side of the bridge part 23b as a punched part.
is what is left behind. As a result, a slot 18' having a shape as shown in FIG. 11 is formed. In this case, in the punched part 23' in which the slot 18' is formed, if the distance between the adjacent main parts 23a is k, then the shoulder part 2
Distance 6' with respect to the shortest distance S on the outer circumferential side when 3c is not available
The dimensions of are expanded to be approximately equal to the distance.

According to the above configuration, the magnetic flux Φ entering the laminated iron core 17' is
As shown in the figure, there is no locally concentrated portion between the slots 18', and a substantially uniform magnetic flux density can be maintained.

In other words, if the shoulder portion 23c is not provided,
Due to design considerations, the shortest distance S mentioned above is shorter than the distance between the slots, so the density of magnetic flux Φ increases in this part, resulting in a laminated core 1 as shown in Figure 1.
7 may become overheated in that part, or the characteristics may deteriorate. and,
Conventionally, in order to prevent this and obtain the originally required magnetic flux density, the gap between the slots was made wider or the laminated core 17 was made larger, but the laminated core 17' of this embodiment By providing the shoulder portion 23c to avoid concentration of magnetic flux Φ as shown in FIG. It is.

In each of the above embodiments, the protrusions are formed by cutting and bending, but the present invention is not limited to this, and the protrusions may be formed by bulging a steel plate.

Furthermore, in each of the above embodiments, the case where the secondary conductor is formed by casting has been described, but the invention is not limited to this. It can also be applied to things.

Further, in each of the above embodiments, the slot 18 is of a fully closed type, but the slot 18 is not limited to this, but may be of a semi-closed type, or a slot having a deep groove cage shape in addition to the normal cage shape. Alternatively, it may be applied to a laminated core 17'' having a double cage-shaped slot 18' as shown in FIG. However, the range is not limited to this and may be within the range shown in formula (A).

In each of the above embodiments, the case where two unit blocks 24 and 25 are provided is described, but the invention is not limited to this, and three or more unit blocks may be provided without departing from the gist of the present invention. Various modifications are possible.

[Effects of the Invention] According to the squirrel cage rotor according to claim 1, when the punched portion of the steel plate is configured as a laminated core, the bridge portion or opening of the slot is separated from the center line of the main portion by the formula (A). ) is set to the distance d in the range shown by ), it is possible to obtain the same effect as applying skew without applying mechanical skew when laminating the steel plates. As a result, the rotor can suppress as much as possible the generation of abnormal torque due to harmonic components, and also suppress the generation of vibration and noise as much as possible, and can effectively utilize the secondary conductor to improve efficiency.

In this case, since the steel plates are formed with protrusions, the laminated cores can be laminated easily and quickly without requiring special jigs or techniques when forming the laminated core.

Furthermore, since mechanical skewing is not performed, the position of the protruding portion of the steel plate remains constant, and the manufacturing of the steel plate itself has an excellent effect in that the cutting die is simple and inexpensive.

According to the squirrel cage rotor according to the second aspect of the present invention, the punched portions of the steel plate are arranged so that the intervals between the punched portions for forming the slots are approximately the same up to the outer periphery.
Since the dimensions are made to be the same, local concentration of magnetic flux between the slots can be avoided, and abnormal temperature rise and deterioration of rotor characteristics that occur due to this can be prevented. In other words, there is no need to increase the size in order to reduce the magnetic flux density, and the design can be made smaller and lighter, which is an excellent effect.

[Brief explanation of the drawing]

Figures 1 to 5 are principle diagrams for explaining the present invention in detail. Figure 1 is a partially cutaway perspective view of the appearance of the laminated core, and Figure 2 is an enlarged view of the protrusion. 3 is an explanatory diagram showing the state of magnetic flux entering the slot, FIG. 4 is an explanatory diagram showing the electromotive force induced in the conductor, and the right figure is a diagram showing various calculation examples. 6 to 10 show a first embodiment of the present invention, in which FIG. 6 is an enlarged view of a part of the steel plate, FIG. 7 is an enlarged perspective view of a protrusion, FIG. 8 is a diagram showing the entire steel plate, FIG. 9 is a vertical cross-sectional side view of the entire configuration, and FIG. 10 is a diagram showing the result of calculating the skew coefficient by 1. 11 to 14 show a second embodiment of the present invention, FIG. 11 is a diagram equivalent to FIG. 1, FIG. 12 is a diagram equivalent to FIG. 6, and FIG. 13 is an explanation of the operation showing the state of magnetic flux. 14 are views corresponding to FIG. 12 showing a modification of the first and second embodiments. In the drawing, 1, 17, 17' and 17' are laminated cores, 2.
23 and 23' are punched parts, 3, 22 and 22' are steel plates,
4^+4B and 24.25 are unit blocks, 5.18.
18' and 18' are slots, 5a and 23a are main parts,
5b and 23b are bridge parts (or openings), 6 and 1
9 is a secondary conductor, 11 is a stator, 12 is a stator core, 15
Ladder-shaped rotor, 16 is the rotating shaft, 2o is the end ring,
21 is a squirrel cage conductor, and 23c is a shoulder portion.

Claims (1)

[Scope of Claims] 1. In a squirrel cage rotor formed by laminating a predetermined number of steel plates having punched parts for forming slots for accommodating conductors on the outer periphery to form a laminated iron core, the steel plate has a protrusion formed by a bulge or an incision, and
The punched portion of the steel plate is asymmetrical in that the bridge portion or opening on the outer peripheral side is shifted to one side by a distance d that satisfies the following condition with respect to the center line of the main portion in which the conductor is housed. The laminated iron core is formed by combining a plurality of unit blocks in which a plurality of unit blocks are stacked so that the protrusions overlap with the steel plates aligned in the direction and position of the slot, and each unit block is formed into a shape. A squirrel cage rotor, characterized in that the directions of the slots are different between each other and the main parts overlap. πD/4(z+p)≦d≦πD/4(z+p) However, D
: Rotor diameter z: Number of slots in the corresponding stator p: Number of pole pairs 2. The punched parts of the steel plate are made so that the intervals between the punched parts for forming slots are approximately the same size up to the outer periphery of the steel plate. Claim 1 characterized in that it is formed in an asymmetrical state.
Squirrel cage rotor as described.