JP6613790B2 - Solid rotor induction motor and method of manufacturing the same - Google Patents

Description

  The present invention relates to a solid rotor induction motor and a method for manufacturing the same.

  In recent years, an electric motor used as a main engine of an EV (Electric Vehicle) or an HEV (Hybrid Electric Vehicle) has been increasingly used in a high-speed rotation region in order to obtain a small size and a large output. Generally, a permanent magnet motor is more suitable than an induction motor in order to reduce the size and output of the motor. Moreover, the permanent magnet motor is superior in terms of efficiency. However, the permanent magnet electric motor has a complicated structure in which a permanent magnet is arranged on the surface or inside of the rotor, and has a drawback that it is weak against centrifugal force. On the other hand, among induction motors, a solid rotor induction motor using a massive iron core for the rotor core basically consists of a rotor core consisting of a massive iron core and a shaft fixed to the rotor core. Robust. For this reason, the solid rotor induction motor can rotate at a high speed that cannot be realized by a permanent magnet motor.

However, in the solid rotor induction motor, when the rotor core has the simplest cylindrical shape, there is a disadvantage that the efficiency is particularly low among the induction motors. This is because when a cylindrical rotor core is used, the secondary current (inductive current) also flows in a direction that does not generate torque. Therefore, in order to generate the same torque, an extra primary current (stator of the stator) This is because it is necessary to pass a current flowing through the winding.
As a method of solving this problem, for example, as described in Non-Patent Document 1, there is a method of providing a groove along the axial direction on the outer periphery of the rotor core. Thus, by providing the groove, the secondary current flows in the axial direction at the portion of the rotor core along the groove, so that a larger torque can be generated under the same primary current. Become. Thereby, the copper loss in the winding on the stator side can be reduced and the efficiency can be improved.

"A method for calculating the starting characteristics of a solid rotor induction motor with an end ring", IEEJ Transactions D, Vol. 112No. 8, p764-770, 1992

However, in the case of the solid rotor induction motor shown in this conventional non-patent document 1, since a groove is provided along the axial direction on the outer periphery of the rotor core, there is a problem that excessive windage loss occurs during high-speed rotation. is there.
The windage loss is a mechanical loss caused by air flow or friction generated between the stator and the rotor when the motor rotates, and generally increases in proportion to the third to fourth power of the rotation speed. Go. For this reason, wind loss hardly poses a problem in a general industrial low-speed rotary motor, whereas in many cases, for example, a high-speed rotary motor of about 20000 rpm cannot ignore the influence of wind loss.

In particular, in the case of the solid rotor induction motor shown in Non-Patent Document 1, since a groove is provided along the axial direction on the outer periphery of the rotor core formed in a cylindrical shape, the inner peripheral surface of the stator core formed in a cylindrical shape The gap between them does not become a double circle of perfect circles when viewed from the axial direction, turbulence occurs, and windage loss further increases.
When the windage loss increases, the efficiency does not increase as expected even if grooves are provided on the outer periphery of the rotor core, and there is a possibility of causing a failure due to dielectric breakdown due to overheating of the gap portion.
Therefore, the present invention solves this conventional problem, and its purpose is to reduce copper loss in the winding on the stator side to improve efficiency and to reduce wind loss. An object of the present invention is to provide a solid rotor induction motor and a method for manufacturing the same.

In order to achieve the above object, a solid rotor induction motor according to an aspect of the present invention includes a cylindrical stator core having an inner peripheral surface formed in a cylindrical shape and a plurality of teeth provided on the stator core. A stator having a plurality of windings wound around each and a cylindrical massive iron core that is rotatably arranged on the inner peripheral side of the stator core and whose outer peripheral surface is formed into a cylindrical shape. A rotor core and a rotor having a shaft fixed to the rotor core, and the rotor core has an outer peripheral surface in a cylindrical shape, and an axial direction of the rotor core on a part of the outer periphery. The non-magnetic portion extends in the direction of the axis, and the shape of the non-magnetic portion viewed from the axial direction is a semicircular shape .

Further, a method for manufacturing a solid rotor induction motor according to another aspect of the present invention includes a step of forming a cylindrical stator core having an inner peripheral surface formed in a cylindrical shape, and a plurality of the stator cores provided in the stator core. A step of winding a plurality of windings around each of the teeth, a step of forming a rotor core made of a cylindrical massive iron core whose outer peripheral surface is formed in a cylindrical shape, and fixing a shaft to the rotor core And a step of rotatably disposing the rotor core on the inner peripheral side of the stator core, and the step of forming the rotor core is a step of forming the material to be the massive iron core into a cylindrical shape And forming a non-magnetic part by demagnetizing a part of the outer periphery of the material formed into a cylindrical shape, and the shape of the non-magnetic part viewed from the axial direction is a semicircular shape the gist that it is in.

  According to the solid rotor induction motor and the method for manufacturing the same according to the present invention, the solid rotor induction that can improve the efficiency by reducing the copper loss in the winding on the stator side and can reduce the wind loss. An electric motor and a manufacturing method thereof can be provided.

It is a schematic structure figure of a solid rotor induction motor concerning one embodiment of the present invention. It is a schematic block diagram of the rotor in the solid rotor induction motor shown in FIG. It is a schematic block diagram of the rotor in the solid rotor induction motor which concerns on a reference example.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a solid rotor induction motor 1 according to an embodiment of the present invention includes a cylindrical frame 2, a stator 10 disposed on the inner peripheral side of the frame 2, and an inner periphery of the stator 10. And a rotor 20 that is rotatably arranged opposite to the gap G with a predetermined gap G therebetween.
Here, the stator 10 has a cylindrical stator core 11 in which an inner peripheral surface 11a is formed in a cylindrical shape, and 24 formed on the inner peripheral surface 11a side of the stator core 11 at equal intervals in the circumferential direction. The slot 12 and the 24 teeth 13 are provided. A winding 14 wound in the slot 12 is wound around each of the plurality of teeth 13.

  As shown in FIGS. 1 and 2, the rotor 20 is fitted into a rotor core 21 made of a cylindrical massive iron core having an outer peripheral surface 21a formed in a cylindrical shape, and a center hole 21b of the rotor core 21. And a shaft 3 which is inserted and fixed. The meaning of the “cylindrical shape” of the rotor core 21 means that the outer peripheral surface 21a of the rotor core 21 is a perfect circle when viewed from the axial direction, and may not be a perfect circle. From the point of doing, it is meant to include the case of a shape close to a perfect circle. The rotor core 21 is rotatably arranged on the inner peripheral side of the stator core 11.

  And the rotor core 21 is provided with the nonmagnetic part 22 extended in the axial direction of the rotor core 21 in a part of outer periphery, keeping the outer peripheral surface 21a cylindrical. More specifically, the outer periphery of the rotor core 21 includes 16 pieces at equal intervals in the circumferential direction along the outer peripheral surface 21a of the rotor core 21 so as not to protrude from the outer peripheral surface 21a of the rotor core 21. Sixteen nonmagnetic portions 22 extending in the axial direction are provided. Each nonmagnetic portion 22 extends along the axial direction of the rotor core 21 from one end surface in the axial direction of the rotor core 21 to the other end surface.

Here, the meaning of “non-magnetic” that defines the non-magnetic portion 22 includes all of paramagnetism, diamagnetism, and antiferromagnetism, and also includes so-called weak magnetism. Further, the shape of each nonmagnetic portion 22 viewed from the axial direction is not limited, but in the present embodiment, it is generally semicircular.
When a current flows through the winding 14 on the stator 10 side, each non-magnetic portion 22 has a secondary current (inductive current) that tries to cancel it by a rotating magnetic field applied from the stator 10 side. This secondary current receives a force from the rotating magnetic field, and the rotor core 21 rotates in the same direction as the rotating magnetic field.

  At this time, the secondary current flows in the axial direction of the rotor core 21 in each non-magnetic portion 22 and does not flow in a direction in which torque is not generated. Therefore, the cylindrical core (without the non-magnetic portion) In order to generate the same torque as that used, it is not necessary to pass an extra primary current (current flowing through the winding 14 of the stator 20). For this reason, it becomes possible to generate a larger torque under the same primary current, and it is possible to improve the efficiency by reducing the copper loss in the winding 14 on the stator 10 side.

Further, since the outer peripheral surface 21a of the rotor core 21 is held in a cylindrical shape, the gap G between the outer peripheral surface 21a of the rotor core 21 and the inner peripheral surface 11a of the stator core 11 is viewed from the axial direction. It has a double circular shape, can reduce windage loss, and can be suitably applied to a high-speed rotating motor of about 20000 rpm.
In addition, since the nonmagnetic part 22 is provided in multiple numbers by the circumferential direction along the outer peripheral surface 21a of the rotor core 21 in the form which does not protrude from the outer peripheral surface 21a of the rotor core 21, it is secondary current. A plurality of non-magnetic portions 22 flowing through the rotor core 21 are arranged at equal intervals in the circumferential direction along the outer peripheral surface 21a of the rotor core 21, and a steady torque can be obtained in the circumferential direction of the rotor core 21.

On the other hand, the rotor 20 in the solid rotor induction motor according to the reference example shown in FIG. 3 includes a rotor core 21 made of a bulk iron core, and a shaft 3 fitted and fixed in the center hole 21 b of the rotor core 21. Yes.
Here, the rotor core 21 is provided with a plurality of grooves 23 extending in the axial direction of the rotor core 21 at equal intervals in the circumferential direction on the outer periphery of the cylindrical massive iron core. The outer peripheral surface 21 a of the rotor core 21 has a plurality of concave shapes formed at equal intervals in the circumferential direction when viewed from the axial direction due to the presence of the plurality of grooves 23.
According to the solid rotor induction motor having the rotor 20 shown in FIG. 3, by forming the groove 23 extending in the axial direction on the outer periphery of the rotor core 21, it is possible to reduce the copper loss in the winding on the stator side. Although it is possible, air turbulence is generated in the vicinity of the groove 23 during high-speed rotation, which increases windage loss.

Next, a manufacturing method of the solid rotor induction motor 1 shown in FIG. 1 will be described.
In manufacturing the solid rotor induction motor 1, first, the stator 10 is manufactured.
The manufacturing process of the stator 10 includes a process of forming a cylindrical stator core 11 in which the inner peripheral surface 11a is formed in a cylindrical shape (stator core forming process), and a plurality of (this book) provided in the stator core 11. In the embodiment, a step (winding winding step) of winding a plurality of windings 14 around each of the 24 teeth 13 is included.

Here, in the stator core forming step, a plurality of (24 in this embodiment) slots 12 and a plurality (24 in this embodiment) of teeth 13 are formed of a soft magnetic material. A two-dimensional annular shape having a portion to be pressed is punched by punching, and a required number of layers are stacked and fixed in the stacking direction by caulking or welding. Thereby, the stator core 11 is formed. Examples of the plate material made of a soft magnetic material include a non-oriented electrical steel sheet. When forming the stator core 11, the soft magnetic ferrite material may be pressed into a predetermined three-dimensional shape and sintered.
In the winding winding step, a material having conductivity and having an insulated surface is prepared as a material for the winding 14. For example, a generally used magnet wire is suitable as the material of the winding 14.
Thereby, the stator 10 is manufactured.
Then, after the stator 10 is manufactured, the stator 10 is fixed by the frame 2.

Next, the rotor 20 is manufactured.
The manufacturing process of the rotor 20 includes a process of forming a rotor core 21 made of a cylindrical massive iron core whose outer peripheral surface 21a is formed in a circular shape when viewed from the axial direction (rotor core forming process), and a rotor core. 21 to fix the shaft 3 to the shaft 21 (shaft fixing step).
The rotor core forming step forms a non-magnetic portion by demagnetizing a part of the outer periphery of the cylindrically formed material and a step of forming the material to be a massive iron core into a cylindrical shape. Process.

  Here, a martensitic stainless material is used as a material in the step of forming a material that becomes a massive iron core into a cylindrical shape, that is, a material of the rotor core 21. In addition, SC material, SCM material, etc. can also be used. In the case of using SC material or SCM material, it is necessary to use a modifying substance in the step of forming the nonmagnetic portion. Martensitic stainless steel has a relatively high soft magnetic property when used in an annealed state in which a carbide is dispersed in a ferrite phase, and can contribute to higher torque of an induction motor. Such a martensitic stainless material is cast into a cylindrical massive iron core.

And after making this raw material a cylindrical lump iron core, before demagnetizing, the shaft 3 used as a shaft fixing process is inserted into the center hole 21b by means such as shrink fitting. This shaft fixing step may be performed after demagnetization.
Next, a step of forming a nonmagnetic portion by demagnetizing a portion of the outer periphery of the material formed into a cylindrical shape, that is, a demagnetizing treatment is performed. In this demagnetization treatment, demagnetization is performed at a plurality of locations (16 locations in the present embodiment) at equal intervals in the circumferential direction of the outer peripheral surface of the material formed in a cylindrical shape, A plurality (16 in the present embodiment) of non-magnetic portions 22 are formed at equal intervals in the circumferential direction along the outer peripheral surface of the material to form the rotor core 21.

In the demagnetization treatment, it is most preferable to locally heat the portion to be demagnetized by laser irradiation and quench the portion from the viewpoint of simplicity and the like. Any method can be used. In the demagnetization treatment, the effect of the present invention can be obtained even if part of the magnetism remains after the treatment, or even so-called weak magnetism. It is preferable to sufficiently eliminate magnetism by adjusting
When laser irradiation is performed on a portion to be demagnetized, a plurality of portions to be demagnetized are irradiated from the outer peripheral side of the material. In this case, it is possible to irradiate the whole of a plurality of locations where demagnetization is performed at once, or to scan each location by scanning a laser with a small spot. Further, the rapid cooling after laser irradiation may be air cooling, but water cooling or oil cooling may be performed as necessary.

Moreover, when using SC material, SCM material, etc. as a raw material, in order to stabilize a nonmagnetic austenite phase, provision of modifiers, such as Cr and C, is required. Specifically, laser irradiation may be performed after applying these modifying substances to the outer peripheral surface of the material.
Thus, the rotor 20 is obtained.
Finally, when the rotor 20 is manufactured, the rotor core 21 is rotatably arranged on the inner peripheral side of the stator core 11 via a bearing (not shown) (rotor core arranging step). Thereby, the solid rotor induction motor 1 is manufactured.

As mentioned above, although embodiment of this invention has been described, this invention is not limited to this, A various change and improvement can be performed.
For example, the nonmagnetic portion 22 in the rotor core 21 extends in the axial direction of the rotor core 21 on a part of the outer periphery of the rotor core 21 while keeping the outer peripheral surface 21a of the rotor core 21 in a cylindrical shape. There is no limitation, and the configuration is not limited to a configuration in which a plurality are provided at equal intervals in the circumferential direction along the outer peripheral surface 21 a of the rotor core 21. In the rotor core 21, the outer peripheral surface 21a may be provided at a location where a secondary current is desired to flow while keeping the outer peripheral surface 21a cylindrical.
Further, the number of the non-magnetic portions 22 is limited to 16 and may be an arbitrary number. Further, the number of slots 12 on the stator 10 side is not limited to 24, and may be an arbitrary number.

DESCRIPTION OF SYMBOLS 1 Solid rotor induction motor 3 Shaft 10 Stator 11 Stator core 11a Inner peripheral surface 13 Teeth 14 Winding 20 Rotor 21 Rotor core 21a Outer peripheral surface 22 Nonmagnetic part

Claims (6)

A stator having a cylindrical stator core having an inner peripheral surface formed in a cylindrical shape, a plurality of windings wound around each of a plurality of teeth provided on the stator core, and the stator core A rotor core that is rotatably arranged on the inner peripheral side of the rotor and has a cylindrical core with a cylindrical outer peripheral surface, and a rotor that includes a shaft fixed to the rotor core. ,
The rotor core is provided with a nonmagnetic portion extending in the axial direction of the rotor core in a part of the outer periphery with the outer peripheral surface kept cylindrical, and the shape of the nonmagnetic portion viewed from the axial direction is a semicircle Solid rotor induction motor characterized by its shape .   2. The non-magnetic portion is provided in a plurality at equal intervals in the circumferential direction along the outer peripheral surface of the rotor core so as not to protrude from the outer peripheral surface of the rotor core. The described solid rotor induction motor. A step of forming a cylindrical stator core having an inner peripheral surface formed in a cylindrical shape, a step of winding a plurality of windings around each of a plurality of teeth provided on the stator core, and an outer peripheral surface A step of forming a rotor core formed of a cylindrical massive iron core formed in a cylindrical shape, a step of fixing a shaft to the rotor core, and the rotor core being rotatable on the inner peripheral side of the stator core And a process of arranging in
The step of forming the rotor core includes a step of forming the material to be the lump core into a cylindrical shape, and a non-magnetic portion by demagnetizing a part of the outer periphery of the cylindrically formed material. look including a step of forming a method for producing a solid rotor induction motor the shape of the nonmagnetic portion as viewed in the axial direction, characterized in that has a semicircular shape.   The step of forming the non-magnetic portion is performed by demagnetizing a plurality of non-magnetic portions at a plurality of equally spaced intervals in the circumferential direction of the outer peripheral surface of the material formed in a cylindrical shape. 4. The method of manufacturing a solid rotor induction motor according to claim 3, wherein the solid rotor induction motor is formed at equal intervals in the circumferential direction along the outer peripheral surface.   5. The manufacture of a solid rotor induction motor according to claim 3, wherein the demagnetization is performed by locally heating the portion to be demagnetized by laser irradiation and rapidly cooling the portion. Method.   The method of manufacturing a solid rotor induction motor according to any one of claims 3 to 5, wherein a martensitic stainless material is used as the material.

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