JPS60167639A - Magnetic crown of rotary electric machine - Google Patents

Abstract

PURPOSE:To uniformly form a pulsating magnetic flux at every slot and to alleviate the concentrated magnetism at the end of a stator core by coating a magnetic crown on the core. CONSTITUTION:A stator core 1 which contains a coil 4 in a semiclosed slot is fixedly disposed in a housing frame 11. A magnetic crown 12 made of a cylindrical magnetic material is closely disposed on the inner peripheral surface of the core 1 and hence the surface opposed through an air gap 7 with a rotor 8. A rim 12a is so formed as to enclose the core 1 at both ends of the crown 12, i.e., at a position contacted with the end of the core 1. Thus, a pulsation of an air gap magnetic flux can be reduced without inserting a magnetic wedge at every slot, and a concentrated magnetic flux at the end of the core can be alleviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic crown for a rotating electric machine, and in particular to a magnetic crown for a rotating electric machine suitable for reducing secondary loss and improving motor characteristics, such as a hysteresis motor. Regarding the crown.

[Background of the invention]

-a Hysteresis motor uses a material with a large hysteresis loop for the rotor material (for example, holding force Hc = 50 to 10
0 oersted, residual magnetic flux density B r =6000-1
5,000 Gauss), and its operating principle is based on the magnetic hysteresis phenomenon of the rotor.6 Also, the generated torque T
It is well known that T=fXSXV (f: power supply frequency, S: area of hysteresis loop, J: rotor volume). Based on this operating principle, a hysteresis motor requires a large amount of magnetomotive force on the rotation side, and therefore, in order to increase the power factor, it is necessary to reduce the gap length and reduce the magnetomotive force in the gap by that amount.

By the way, when the air gap length is made smaller, a harmonic hysteresis loop is created in the rotor due to stator slot ripple and concentration of magnetic flux at the end of the stator core on the side facing the rotor, and the output decreases by that amount. , which has the disadvantage of lower efficiency. Therefore, in order to increase motor efficiency, it is important to take measures to reduce throttle ripple and magnetic flux concentration.

This becomes even more important when obtaining ultra-high speed rotation. That is, in order to obtain ultra-high speed rotation, it is generally used in an atmosphere close to vacuum.

Therefore, it is easy to cool the stator side that is in contact with the motor housing or the outer casing, but the rotor side cannot be cooled by conduction and must rely on heat dissipation by radiation. Therefore, on the rotor side, even a small amount of heat generated due to secondary loss causes the temperature of the rotor to rise, making ultra-high speed rotation impossible.

Various proposals have been made to overcome these drawbacks, one of which is to use a magnetic wedge in the slot portion. A specific example is shown in FIG.

FIG. 1 is a sectional view of a main part of a general cylindrical hysteresis motor as viewed from the axial direction. The coil 4 is wrapped in a U-shaped slot insulator 3 in the half-open slot 2 of the stator core l, and the top is held down with an insulating wedge 5 such as Nomex or polyester film to prevent the coil 4 from jumping out. At the same time, we aim to improve the characteristics of the motor.
A stator is constructed by inserting a magnetic wedge 6 made of a magnetic machine into the semi-closed slot 2. A rotor 8 made of a rotatable hysteresis material is disposed on the inner peripheral side of the stator core 1, supported by a rotating shaft (not shown) through a gap 7.

By applying three-phase alternating current to the coil 4, the stator core 1 generates a rotating magnetic field.

This rotating magnetic field and the magnetic hysteresis of the rotor 8 generate torque within the rotor 8, and the rotor 8 rotates in a fixed direction.

By the way, in the case of the method shown in FIG. 1, since the magnetic wedge 6 is inserted into the semi-closed part 2a of the laminated thin iron plates forming the stator core 1, irregularities may occur in the way the thin iron plates are stacked. In consideration of this, the width dimension of the magnetic wedge 6 must be made smaller than the punching dimension of the semi-closed part 2a. Furthermore, considering the thermal expansion of the magnetic wedge 6 and the machining tolerance during manufacturing, the width of the magnetic wedge 6 must be further reduced. Therefore, a gap is created between the semi-closed portion 2a and the magnetic wedge 6, and the magnetomotive force consumed by this gap prevents the magnetic wedge from being sufficiently effective.

Furthermore, with this configuration, it is structurally impossible to alleviate the concentration of magnetic flux that occurs at the axial end of the stator core on the side facing the rotor. Furthermore, if a gap is created between the semi-closed opening 2a and the magnetic wedge 6, the magnetic wedge 6 may move inside the semi-closed opening or fall off due to magnetic vibrations, etc., so some measure should be taken to prevent it from falling off. must be given. As a result, the number of parts increases and the number of assembly steps increases, resulting in an increase in price.

On the other hand, in order to overcome the above-mentioned drawbacks, a proposal as shown in FIG. 2 has also been made. That is, a magnetic cylinder 10 made of a magnetic material and having the same dimensions as the stacking thickness of the stator core 1 is disposed on the inner circumferential surface of the stator core facing the rotor 8. According to this, the semi-closed part 2a with the above-mentioned drawback
The problem of magnetomotive force caused by the gap caused by the manufacturing tolerance of the magnetic wedge 6 can be solved. In other words, the slot ripple due to the increase in magnetomotive force at the semi-closed part 2a is
The surface of the stator teeth 9 is smoothed by the magnetic cylinder 10, and the adverse influence on the rotor 8 is alleviated. but,
Even in the present invention, since the axial dimension of the magnetic cylinder 10 is the same as the stacked thickness dimension of the stator core 1, it is not possible to completely alleviate the magnetic flux concentration at the ends of the stator core.

Furthermore, in the above proposal, it is very difficult to attach the magnetic cylinder IO to the surface of the fixed core tooth 9.

That is, methods for attaching the magnetic cylinder include welding, adhesion, and covering with mold resin.

The welding method results in electrical short-circuiting of the laminated stator core, which is undesirable because it causes eddy current generation in the stator core. Furthermore, in the method of covering with adhesive or molding resin, the adhesive or resin material is thermally and mechanically weak, so there is a risk that the magnetic cylinder will peel off and move and fall off.

As described above, in the prior art, the main focus was placed on reducing the slot ripple, and therefore the reduction of secondary loss caused by the pulsation of the concentrated magnetic flux generated at the end of the stator core was not completely improved.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and also to smooth out the concentrated magnetic flux at the end of the stator core.
The next object is to provide a magnetic window for a rotating electrical machine that is more effective in reducing loss.

[Summary of the Invention 3] The present invention provides a cylindrical hysteresis motor in which the magnetic flux density distribution in the gap between the stator core and the rotor is reduced to the slot portion or the stator core, as shown in FIGS. 3 and 4. Experiments have confirmed that it is particularly concentrated at the edges. This concentrated magnetic flux is effectively smoothed by magnetic windows placed so as to cover the ends of the stator core.
The purpose is to reduce the following losses. That is, in a cylindrical motor, the magnetic flux density distribution in the circumferential direction at the center of the core in the gap 7 where the stator core 1 and the rotor 8 face each other is as shown in FIG. Similarly, the magnetic flux density in the axial direction at the center of the stator teeth 9 is distributed as shown in FIG. In this way, the magnetic flux incident on the rotor 8 largely fluctuates and concentrates at the semi-closed portion 2a or the stator core end 9a. Due to fluctuations and concentration of this magnetic flux, eddy current flows within the rotor 8, causing secondary loss.

Therefore, by smoothing this magnetic flux density distribution, secondary loss can be reduced.

[Jl! EMBODIMENT OF THE INVENTION] Hereinafter, one embodiment of the present invention will be described with reference to FIG. Here, the same reference numerals are used for the same components as in the conventional example. In FIG.

Stator core 1 with coil 4 housed inside half-open Rosron 1
is fixedly arranged within the housing frame ll. A magnetic window 12 made of a cylindrical magnetic phase is provided on the inner circumferential surface of the stator core 1, that is, the surface facing the rotor 8 via the air gap 7.
are placed in close contact. Both ends of the magnetic window 12, that is,
At the end of the stator core 1, a rim 12a is formed so as to wrap around the stator core 1. The rotor 8 is fixed to a rotating shaft 13 and rotatably supported by the housing frame 11 via a bearing 14 .

By applying a three-phase alternating current to the coil 4 wound around the rotor core l, a rotating magnetic field is generated, and this rotating magnetic field and the magnetic hysteresis of the rotor 8 generate 1-lux in the rotor. The rotor rotates.

However, according to the stator structure according to this embodiment, the rotating magnetic flux radiated from the stator core has a magnetic flux distribution smoothed by the magnetic windows. That is, the concentration and drop of magnetic flux in the slot semi-closed portion shown in FIG. 3 is made uniform by the magnetic windows closely arranged on the stator core teeth, and the slot ripple is reduced. In addition, the phenomenon of concentration of magnetic flux at the end of the stator core shown in Fig. 4 is due to the fact that the end of the stator core is covered with a magnetic window rim as described above, and the bending of the magnetic crown when forming the ribs. Due to the curved surface, the concentration of magnetic flux is relaxed, and the distribution of magnetic flux entering the gap, that is, the rotor, is made uniform.

Therefore, according to the stator structure according to this embodiment.

Pulsation of the air gap magnetic flux can be reduced without inserting a magnetic wedge in each slot. Therefore, the occurrence of hysteresis loss due to slot ripple in the rotor can be suppressed, a decrease in motor output can be prevented, and efficiency can be improved.

Note that it is also possible to use the conventional method using a magnetic wedge and the method using the magnetic window according to this embodiment. In this case.

Needless to say, the slot ripple can be further reduced. Moreover, the above-mentioned magnetic wedge can be prevented from falling off.

Further, a feature of this embodiment is that a rib is provided on the magnetic window. This has a great effect on alleviating the concentrated magnetic flux at the end of the iron core, which could not be solved with the conventional method, and helps reduce secondary loss. Furthermore, the ribs can press down the laminated stator core tooth portions in the stacking direction, thereby preventing chatter vibrations due to separation of the tooth portions and also being effective in preventing increases in iron loss. Furthermore, providing the magnetic window with ribs makes it difficult to secure the magnetic crown to the stator core. That is, after inserting a cylindrical magnetic crown into the inner circumferential surface of the stator core, both ends of the magnetic crown are pressed against the ends of the stator core, and the magnetic crown is easily folded by bending and crimping the ends of the stator core. It can be fixed to the stator core quickly, reducing the number of parts and assembly man-hours, which is effective in reducing costs.

Although this embodiment has been explained using a cylindrical motor with a gap in the radial direction as an example, the same effect can be obtained by using the above-described structure in a flat motor with a gap in the axial direction. Needless to say. Furthermore, secondary losses can be reduced not only in hysteresis motors but also in general induction machines, synchronous machines, etc. by providing the magnetic shape as described above. Furthermore, when a magnetic crown is used in the rotor of a rotating machine in which the rotor has a field function, the same effect as described above can be obtained, and the effect can also be exhibited in reducing the lamination of the rotor.

〔Effect of the invention〕

As described above, the present invention uses the cylindrical hysteresis mode to completely equalize the pulsating magnetic flux for each slot I~, and
Concentrated magnetism at the end of the iron core can be relaxed, and therefore secondary loss can be significantly reduced, suppressing the temperature rise of the rotor and greatly improving motor efficiency. It can also contribute to cost reduction.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main part when using a conventional magnetic wedge, Figure 2
The figure is a cross-sectional view of the main part when using a conventional magnetic cylinder, a diagram explaining the magnetic flux density distribution in the gap seen in the circumferential direction in Fig. 3, and a diagram showing the magnetic flux density distribution in the gap seen in the axial direction in Fig. 4. FIG. 5, which is an explanatory diagram of the density distribution, is a sectional view showing an embodiment of the hysteresis motor according to the present invention.

Claims (1)

[Claims] 1. A stator core is provided with a groove for accommodating the winding, and a stator formed by accommodating the winding in the groove is opposed to the stator through a gap. In a rotating electrical machine consisting of a rotor arranged in a rotor, a thin iron plate made of a magnetic material, which is longer than the effective core length of the stator or rotor, is uniformly disposed on the air gap side surface of the stator core or the rotor core. A magnetic crown for a rotating electrical machine characterized by being closely fixed. 2. The rotation according to claim 1, characterized in that a portion of the thin iron plate protruding from the effective portion of the stator core or the rotor core is bent in a direction opposite to the gap side. Electric magnetic crown. 3. A magnetic crown for a rotating electrical machine according to claim 2, characterized in that the bent portion of the thin iron plate protruding from the effective length of the iron core does not form a corner at least on the air gap side.