JPH1080077A - Induction motor of synthetic resin mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to achieve the compact configuration, low cost or high efficiency of a motor by determining the ratio of the width of a stator core yoke with respect to the width between teeth in correspondence with the number of pulse of the motor and the number of the slots of the stator, and approximately equalizing the flux density of the yoke part with the flux density of the teeth part. SOLUTION: A stator 7 is constituted by the molding with synthetic resin 6 after a winding 5 is wound around a stator core 4 formed by laminating magnetic steel sheets. The stator core 4 comprises a plurality of teeth 8 for guiding the magnetic flux to the side of a rotor in the laminated layer of many electromagnetic steel plate sheets, punched in the same shape, and yokes 9 for linking the teeth and slots 10, being winding spaces. In the stator core 4, a yoke width (y) is set as the value indicated by y=nt/π with respect to the teeth width (t). For example, in 4-pole 24-slots, the yoke width (y) is set as y=5.7mm with respect to the teeth width (t) of t=3mm, which is 1.9 times. Thus, the flux densities of the yoke part and the teeth part of the stator core are made to be approximately equal, and the compact configuration of the motor is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a stator core of an induction motor molded with a synthetic resin.

[0002]

2. Description of the Related Art Conventionally, steel plate bracket induction motors have been employed in fan motors for air conditioners and motors for washing machines in the home appliance industry. Generally, a steel plate bracket induction motor is assembled by press-fitting a steel plate bracket 1 constituting a bearing holding portion into an outer peripheral portion of a stator 2 as shown in FIG. Insulation distance must be ensured as described in the Electrical Appliance and Material Control Law, and the conventional stator core takes the yoke width of the stator core sufficiently to ensure the insulation distance. In general, the yoke width is set to be 2 to 4 times the tooth width. For example, if an example of a conventional stator core is shown in FIG. 5, the yoke width y of the stator core is 2.2 times the tooth width t. The yoke width y of the stator core is greatly related to the magnetic flux density of the yoke portion.With the above configuration, the conventional stator core has a tendency that the magnetic flux density of the yoke portion is lower than the magnetic flux density of the teeth portion, There was a case where the yoke width was too large.

However, in recent years, electric motors in which the stator is molded with synthetic resin have become mainstream. In a synthetic resin-molded induction motor, the stator winding is integrally molded. It is no longer necessary to provide an insulation distance as in the case of the steel plate bracket induction motor described above. For this reason, it is no longer necessary to increase the yoke width of the stator core as in the past, but in fact, the stator core of the conventional steel plate bracket induction motor can be shared as it is, Also in the iron core, the yoke width y is set to be 2 to 4 times the tooth width t as in the related art. Exceptionally, there are four times or more, but almost no less than two times.

[0004]

However, as described above, the yoke width y of the stator core is set to be two to four times the tooth width t, and the stator core yoke width is made to have a margin. Is molded, the outer diameter of the motor becomes unnecessarily large as in the conventional synthetic resin molded induction motor shown in FIG. 3, which is disadvantageous in terms of material costs. Further, by increasing the yoke width y, the area of the slot is limited and the amount of winding is reduced, which is disadvantageous in terms of efficiency.

The present invention solves the above problems,
An object of the present invention is to provide a synthetic resin molded induction motor that is smaller, less expensive, and more efficient than a conventional synthetic resin molded induction motor.

[0006]

According to the present invention, a ratio of a stator core yoke width y to a teeth width t is determined according to the number of motor poles and the number of stator slots. did. Thereby, the magnetic flux density of the yoke portion is made substantially equal to the magnetic flux density of the teeth portion.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above-mentioned problems, the present invention is directed to a plurality of teeth laminated with magnetic steel sheets, a yoke connecting them together, and a slot which is a space formed by the teeth and the yoke. And a plurality of stator windings wound around the plurality of slots, and a synthetic resin that integrally forms and surrounds the stator winding and at least a portion of the stator core. An induction motor having a rotor, wherein the ratio of the width of the yoke to the width of the teeth is determined according to the number of poles and the number of slots of the motor, so that the magnetic flux density of the yoke portion and the magnetic flux density of the teeth portion are determined. They are almost equal.

In the present invention, specifically, when the number of poles of the motor is P, the number of slots per pole is n, the width of the yoke is y, and the width of the teeth is t, y = nt / π. It is to become.

Further, in the present invention, the width of the yoke is set within a range of 20% above and below a value determined by the above formula.

By setting the yoke width to an appropriate value according to the amount of magnetic flux, the diameter of the motor can be reduced.
It is possible to reduce the cost by reducing the material cost while reducing the size of the motor. When the diameter of the motor is the same as that of the conventional motor, the slot area can be increased, so that the amount of stator windings can be increased, and high efficiency and high output of the motor can be realized.

[0011]

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

In FIG. 1, a stator 7 is formed by winding a winding 5 around a stator core 4 formed by laminating electromagnetic steel sheets, and then molding the same with a synthetic resin 6.

The stator core 4 shown in FIG. 2 is formed by laminating a number of electromagnetic steel sheets punched in the same shape, and connects a plurality of teeth 8 for inducing magnetic flux to the rotor side and the teeth 8. 9 and a slot 10 as a winding space.

In the stator core 4, the yoke width y is set to a value represented by y = nt / π with respect to the teeth width t. In this embodiment, the number of poles of the motor is set to four, and the stator core has a yoke width y. Since the number of slots is 24, the yoke width is 5.7 mm, which is 1.9 times the tooth width of 3 mm. By doing so, the magnetic flux densities of the yoke portion and the teeth portion of the stator core can be made substantially equal.
The reason will be described below.

Generally, in an induction motor, a magnetic flux Φ per pole, an effective magnetic flux cross-sectional area A per pole, and a gap average magnetic flux density Bg are expressed as Bg = Φ / A. Here, assuming that the pole cross section is α, the inner diameter pitch per pole is τp, and the stator core effective product pressure is L, the effective magnetic flux cross section A can be expressed as A = ατpL. Further, the teeth width t of the stator core, the inner diameter pitch τs per slot, and the teeth magnetic flux density Bt are represented by B
It can be expressed as t = Bgτs / t. The yoke width y of the stator core and the yoke magnetic flux density By can be expressed as By = Φ / 2yL. Here, when Bt = By is substituted as a condition for making the magnetic flux density Bt of the teeth portion and the magnetic flux density By of the yoke portion equal, y = αtτp / 2τs. Here, assuming that the magnetic flux is distributed in a sine wave, α =
Since it is 2 / π, y = tτp / πτs.

That is, the yoke width y of the stator core is determined by the ratio of τp / τs to the tooth width t.
Means the number of slots included per pole. Therefore, if τp / τs = n, y = nt / π is derived.

From this, it can be seen that given the number of motor poles and the number of slots in the stator core, the yoke width y of the stator core is uniquely determined with respect to the teeth width t.

From the above results, since the embodiment of the present invention has 4 poles and 24 slots, the yoke width y of the stator core is set to be 1.9 times the tooth width t, thereby achieving a conventional induction motor. Outer diameter can be reduced compared to
The motor can be reduced in size and cost.

When the stator core has the same outer diameter as the conventional stator core, the slot area of the stator core of the present invention can be increased by the reduced yoke width. It can be seen that efficiency can be increased.

FIG. 6 shows a comparison of the ratio of the yoke width y to the teeth width t of the stator core of the present invention with respect to the typical number of poles and slots of the induction motor.
Shown in

As is apparent from FIG. 6, the stator core of the present invention generally has a smaller yoke width than the conventional one, and the larger the number of motor poles, the more the number of slots in the stator core. It can be seen that the smaller the difference, the greater the difference from the conventional case.

In this embodiment, the numerical value of the ratio of the yoke width y of the stator core to the tooth width t is a fixed numerical value.
Needless to say, a width of about 20% may be provided depending on the application.

[0023]

As is clear from the above, according to the present invention, the yoke width of the stator core can be made smaller than that of the conventional one, and the downsizing, cost reduction or high efficiency of the motor is realized. can do.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a synthetic resin mold induction motor according to an embodiment of the present invention.

FIG. 2 is a stator core diagram according to an embodiment of the present invention.

FIG. 3 is a structural view of a conventional synthetic resin molded induction motor.

FIG. 4 is a structural view of a conventional steel plate bracket induction motor.

FIG. 5 is a conventional stator core diagram.

FIG. 6 is an explanatory diagram showing a ratio of a yoke width to a teeth width.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate bracket 2, 4 Stator iron core 3, 5 Stator winding 6 Synthetic resin 7 Stator 8 Teeth 9 Yoke 10 Slot

Claims (3)

[Claims] 1. A stator core comprising a plurality of electromagnetic steel sheets laminated, a plurality of teeth, a yoke connecting them together, and a slot which is a space formed by the teeth and the yoke, and wound around the plurality of slots. An induction motor having a plurality of stator windings and a stator made of a synthetic resin that integrally forms and surrounds the stator windings and at least a portion of the stator core, the width of the yoke being A synthetic resin molded induction motor, wherein the magnetic flux density of the yoke portion is made substantially equal to the magnetic flux density of the teeth portion by determining the ratio of the teeth to the width in accordance with the number of poles and the number of slots of the motor. 2. The number of poles of the motor is P, the number of slots per pole is n, the width of the yoke is y, and the width of the teeth is t.
2. The synthetic resin molded induction motor according to claim 1, wherein y = nt / .pi. 3. The synthetic resin molded induction motor according to claim 2, wherein the width of the yoke is within a range of 20% above and below a value determined by the mathematical formula.