JPH104658A - Induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction motor, having excellent efficiency and being improved in manufacturing precision. SOLUTION: An induction motor 10 is constituted of a stator 20, having a stator core 20, whereon a stator winding 24 is wound and a rotor 30. The rotor 30 is constituted of a rotor core 32 which is supported rotatably in the inner periphery of the stator 20, end rings 36A and 36B formed at the opposite ends of the rotor core 32 by die casting, a solid bar 34 which is inserted in a slot, formed on the outer peripheral side of the rotor core 32 and is connected electrically to the end rings 36A and 36B, formed at the opposite ends and a die-cast bar 36C which is formed in a plurality of second slots, formed on the inner peripheral side of the rotor core 32 to be formed integrally with the end rings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor, and more particularly, to an induction motor using a cage rotor.

[0002]

2. Description of the Related Art In a conventional small squirrel-cage induction motor, a rotor conductor is generally made of aluminum die-cast. On the other hand, in a large squirrel-cage induction motor, the rotor conductor uses a copper bar to reduce the resistance of the conductor. However, in the method using the copper bar, it is necessary to electrically connect the end rings disposed at both ends in the axial direction of the rotor to the copper bar penetrating through the rotor. Since the end ring and the copper were connected, the connection work was very complicated.

On the other hand, for example, Japanese Patent Application Laid-Open No. 4-888
As described in Japanese Patent Publication No. 55-55, in a rotor slot,
With the copper bar having a cross-sectional area smaller than the cross-sectional area of the slot inserted, the end ring is formed by the die-casting method, aluminum is also poured into the slot, and the rotor conductor is formed by the aluminum die-cast and the copper bar. Then, a method of connecting the end ring to the rotor conductor is known.

[0004]

However, in the method in which the rotor conductor is formed by aluminum die casting and a copper bar, the aluminum die casting is axially inserted into the gap between the solid bar inserted into the rotor slot. Because the passage area of aluminum die casting is increased because
Since the cross-sectional area of the copper bar cannot be sufficiently secured and the resistance of the rotor cannot be sufficiently reduced, there is a problem that the rotor loss increases. When the rotor loss increases,
There is a problem that the efficiency is reduced.

On the other hand, if the cross-sectional area of the copper bar is made sufficiently large, the axial cross-sectional area of the die-cast portion in the slot becomes small. Therefore, during aluminum die casting, if one passes through the slot from one end ring part and tries to turn the aluminum hot water to the other end ring part, the hot water does not flow enough and there is a problem of bar breakage in the slot and the end. Problems such as the occurrence of nests in the ring occur. As a result, there is a problem that the resistance of the rotor partially changes. The partial change in the resistance of the rotor generates noise when the induction motor is driven and causes variations in the rotation characteristics. That is, there is a problem that manufacturing accuracy is reduced.

An object of the present invention is to provide an induction motor with high efficiency and improved manufacturing accuracy.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a stator having a stator core wound with a stator winding, and a rotatably held at the inner periphery of the stator. Rotor core, end rings formed by die casting at both ends of the rotor core, and end rings formed at the both ends while being inserted into slots formed in the rotor core. In an induction motor having a solid bar connected thereto, the solid bar is inserted into a plurality of slots formed on an outer peripheral portion of the rotor core, and the slot is formed on an inner peripheral side of the rotor core. A die casting bar integrally formed with the end ring is provided in a plurality of independently formed second slots. With this configuration, the electric resistance of the rotor conductor is reduced. And comb, efficient and moreover, enables improvement in manufacturing accuracy of die-cast bar.

In the induction motor, preferably, the solid bar is made of a metal different from the metal constituting the solid bar, and is covered with a metal compatible with the metal constituting the end ring. With such a configuration, the connection between the solid bar and the end ring can be facilitated.

In the induction motor, preferably, the solid bar is formed by inserting the solid bar into a cylindrical metal and pulling the solid bar to integrally form the solid bar.
With this configuration, the electric resistance of the solid bar can be sufficiently reduced.

[0010] In the induction motor, preferably, the outer peripheral portions at both ends of the solid bar are plated with the metal. With such a configuration, connection with the end ring can be facilitated.

In the above-mentioned induction motor, preferably, the number of slots for forming the die-casting bar is smaller than the number of slots for inserting the solid bars. Can be increased.

In the above induction motor, preferably, a plurality of cooling passage slots formed independently of the slots are provided on the inner peripheral side of the rotor core. The temperature rise during operation can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An induction motor according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a partial sectional view of an induction motor according to one embodiment of the present invention.

In FIG. 1, the stator 2 of the induction motor 10 is
Reference numeral 0 denotes a stator core 22 and a multi-phase stator winding 24 wound around the stator core 22. , Stator 20 is fixedly held on the inner peripheral surface of housing 26. The rotor 30 includes a rotor core 32 formed of a laminated silicon steel plate fixed to a shaft 38, a solid bar 34 inserted into a slot formed on the outer peripheral side of the rotor core 32, and a rotor core 32. It is composed of end rings 36A and 36B formed at both ends, and a die casting bar 36C formed in a slot passing through the rotor core 32.

The detailed structure of the solid bar 34 is shown in FIG.
As will be described later with reference to FIG. End rings 36A and 36B and die casting bar 36
C is integrally formed by a die casting method. As the die casting method, for example, an aluminum die casting method is used. The die casting bar 36C is formed on the inner peripheral side of the rotor core 32.

The shaft 38 is rotatably held by bearings 42 and 44. Bearing 42, 4
4 is supported by end brackets 46 and 48, and the end brackets 46 and 48
Are fixed to both ends.

Next, the sectional structure of the rotor will be described with reference to FIG. FIG. 2 is a cross-sectional view of the rotor of the induction motor according to the embodiment of the present invention, and is a cross-sectional view taken along line AA of FIG.

The rotor conductor of the rotor 30 has twelve solid bars 34 inserted at equal intervals on the outer peripheral side of a rotor core 32 made of laminated silicon steel sheet, and equal intervals on the inner peripheral side of the rotor core 32. And six die casting bars 36C formed by the aluminum die casting method.

The rotor core 32 is composed of laminated silicon steel sheets, and two kinds of holes are previously formed in each silicon steel sheet by a punching press. The first type of holes are formed at equal intervals on the outer peripheral side, and the solid bar 34 is inserted. The second type of holes are formed at equal intervals on the inner peripheral side, and die-cast bars 36C are formed. By laminating such silicon steel plates having two types of holes with the holes aligned, a rotor core 32 having two types of slots on the inner and outer circumferences is formed.

The inside diameter of the slot into which the solid bar 34 is inserted is substantially the same as the outside diameter of the solid bar 34. The solid bar 34 is inserted by driving the solid bar 34 into this slot. The rotor core 32 into which the solid bar 34 is driven is mounted in a die (die) of a die casting machine, and aluminum hot water is injected to form a die casting bar 36C. Also, the end rings 36A, 36B shown in FIG.
Is also integrally formed with the die casting bar 36C.

Next, the structure of the solid bar 34 will be described with reference to FIG. FIG. 3 is a perspective view of a solid bar constituting a rotor conductor of a rotor of an induction motor according to an embodiment of the present invention.

The solid bar 34 comprises a copper bar 34A and a cylindrical aluminum material 34 covering the outer periphery of the copper bar 34A.
B, and both are integrally formed by, for example, drawing. The contact between copper and aluminum can be manufactured with sufficiently low electrical resistance by mechanically applying pressure during the integrated manufacturing to make contact.

In the above configuration, the solid bar 34
Function as a rotor conductor of the rotor 30. That is, as described with reference to FIG. 3, the center of the solid bar 34 is formed of a copper bar, so that the conductivity is high and the current flowing in the solid bar 34 can be increased. Therefore, the efficiency of the induction motor can be increased, and the torque generated by the induction motor can be increased.

In order to increase the generated torque, it is necessary to increase the sectional area of the solid bar 34. However, the slot formed on the outer peripheral side of the rotor core 32 has substantially the same sectional area as the solid bar 34. And, for example,
The cross-sectional area of the copper bar 34A, which is the solid bar 34, can be increased as compared with the conventional method in which the rotor conductor described in JP-A-88855 is formed by aluminum die casting and a copper bar. Can be increased.

Further, on the outer periphery of the solid bar 34, a cylindrical aluminum material 34B is formed integrally with the copper bar 34A, and is made of the same material as the end rings 36A, 36B. Both ends of the solid bar 34 can be in sufficient electrical contact with the end rings 36A, 36B. That is, the connection between the rotor conductor and the end ring
This is easier than connecting a copper rotor conductor and an aluminum end ring.

On the other hand, the die casting bar 36C is used for forming and fixing the end rings 36A, 36B on both sides. End ring 36A and end ring 36
When manufacturing B by aluminum die-casting, aluminum hot water is injected into, for example, the end ring 36A side, and at that time, the hot water is supplied to the slot for the die-casting bar 36C by vacuuming from the end ring 36B side. As a result, the end rings 36A, 36B and the die casting bar 36C on both sides turn around the end ring 36B and are integrally manufactured. That is, the die-casting bar 36C is formed by hardening the aluminum hot water which has passed through the passage at the time of forming the end rings 36A and 36B. At the same time, the end rings 36A and 36B are fixed to the rotor core 32 by die casting bars 36C.

Here, by increasing the cross-sectional area of the slot for the die-casting bar 36C, the aluminum hot water flows sufficiently from the end ring 36A to the end ring 36B to generate nests in the end ring and the bar. Cutting can be prevented. In the conventional method in which the rotor conductor described in Japanese Patent Application Laid-Open No. 4-88855 is formed by aluminum die-casting and copper bar, the cross-sectional area of the aluminum die-casting is reduced in order to mix the copper bar and aluminum die-casting in the same slot. Although it cannot be made sufficiently large, by providing the die-casting bars 36C independently, the cross-sectional area can be made large, so that the occurrence of nests in the end ring and the cutting of the bars can be prevented.

Further, the number of die-casting bars 36C (six) is smaller than the number of solid bars 34 (12). This is to increase the cross-sectional area per die-casting bar 36C, and by doing so, it is possible to more reliably prevent the occurrence of nests and breakage of the bar in the end ring.

Here, the die casting bar 36C is formed at a position on the inner peripheral side of the rotor core 32 and close to the side where the shaft 38 is inserted, and is formed at a position distant from the solid bar 34. The current flowing through the die casting bar 36C does not directly contribute to the torque generated by the induction motor. That is, the function of the die-casting bar 36C is different from that of the conductor on the inner peripheral side in the double-cage induction motor.

Unlike the solid bar 34 made of copper, the die-cast bar 36C has a large electric resistance in that it is made of aluminum, and has a large electric resistance in that it is made of die-cast. Therefore, the current flowing through the die casting bar 36C is extremely smaller than the current flowing through the solid bar 34. The magnetic field formed by the current flowing through the die casting bar 36C concentrates the magnetic flux flowing from the stator to the stator via the rotor in the sectional view shown in FIG. 2 between the solid bar 34 and the die casting bar 36C. Therefore, in this respect, a function is provided to slightly improve the efficiency of the induction motor.

In the above configuration, when the slot of the die casting bar 36C is provided in the core portion of the rotor core 32, the rotor 3
It is conceivable that the magnetic flux density of the core portion 0 increases and the loss increases. However, there is no problem since the magnetic flux density of the core portion of the rotor 30 is generally sufficiently smaller than the magnetic path.

In the above description, as shown in FIG. 3, the solid bar 34 has a structure in which the outer periphery of a copper bar 34A is covered by an aluminum cylinder 34B.
Even if a nickel or chromium plating layer is formed on the outer peripheral portions at both ends of the copper bar, the copper bar and the aluminum end rings 36A and 36B can be easily connected by a die casting method.

According to this embodiment, since the cross-sectional area of the solid bar can be increased, the electric resistance of the rotor conductor can be reduced, and the efficiency of the induction motor can be increased.

Further, by providing the die casting slot on the inner peripheral side of the rotor core independently of the solid bar slot, the cross-sectional area of the slot can be increased, and the occurrence of nests in the end ring and Since the bar can be prevented from being cut, the manufacturing accuracy can be improved.

Next, an induction motor according to another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a cross section of a rotor of an induction motor according to another embodiment of the present invention. 1 and 3 are the same in the present embodiment, and FIG. 4 is a view corresponding to the AA cross-sectional view of FIG.

The rotor conductor of the rotor 30 has twelve solid bars 34 inserted at equal intervals on the outer peripheral side of a rotor iron core 32 made of laminated silicon steel sheet, and has equal intervals on the inner peripheral side of the rotor iron core 32. And six die-casting bars 36C 'formed by the aluminum die-casting method.
Here, the cross section of the die casting bar 36C 'is different from the circular cross section shown in FIG.

The rotor core 32 is composed of laminated silicon steel sheets, and two types of holes are previously formed in each silicon steel sheet by a punching press. The first type of holes are formed at equal intervals on the outer peripheral side, and the solid bar 34 is inserted. The second type of elliptical holes are formed at equal intervals on the inner peripheral side to form a die casting bar 36C '. By laminating such silicon steel plates having two types of holes with the holes aligned, a rotor core 32 having two types of slots is formed.

The inside diameter of the slot into which the solid bar 34 is inserted is substantially the same as the outside diameter of the solid bar 34. The solid bar 34 is inserted by driving the solid bar 34 into this slot. The rotor core 32 into which the solid bar 34 is driven is mounted in a die (die) of a die casting machine, and aluminum hot water is injected to form a die casting bar 36C '. Also, the end rings 36A, 36B shown in FIG.
Is also integrally formed with the die casting bar 36C.

Since the die casting bar 36C 'has an elliptical shape, the cross-sectional area of the slot formed in the rotor core 32 for forming the die casting bar 36C' can be made larger than that shown in FIG. Furthermore, it is possible to prevent the occurrence of nests and breakage of the bar in the end ring. Also, the hot water of die casting can flow sufficiently in the axial direction, and the end rings 36A and 36B can be made firmly.

According to this embodiment, since the cross-sectional area of the solid bar can be increased, the electric resistance of the rotor conductor can be reduced, and the efficiency of the induction motor can be increased.

Further, by providing the die-casting slot on the inner peripheral side of the rotor core independently of the solid bar slot, the cross-sectional area of the slot can be increased, and the occurrence of nests in the end ring and the like can be reduced. Since the breakage of the bar can be further prevented, the manufacturing accuracy can be improved.

Next, a third embodiment of the present invention will be described with reference to FIGS.
An induction motor according to the embodiment will be described. FIG.
FIG. 6 is a view showing a cross section of a rotor of the induction motor according to the third embodiment of the present invention, and FIG. 6 is a side view of the rotor of the induction motor according to the third embodiment of the present invention. 1 and FIG. 3 are also the same in the present embodiment, and FIG. 5 is a view corresponding to the AA cross-sectional view of FIG.
FIG. 6 is a diagram corresponding to a side view of the rotor shown in FIG. 1.

The rotor conductor of the rotor 30 has twelve solid bars 34 inserted at equal intervals on the outer peripheral side of a rotor iron core 32 made of laminated silicon steel sheet, and has equal intervals on the inner peripheral side of the rotor iron core 32. And six die casting bars 36C formed by the aluminum die casting method. Further, six die casting bars 36 are attached to the rotor core 32.
A cooling passage 32A is formed concentrically with C and between each of the six die casting bars 36C.

The rotor core 32 is composed of laminated silicon steel sheets, and two kinds of holes are formed in each silicon steel sheet in advance by a punching press. Twelve circular holes of the first type are formed at equal intervals on the outer peripheral side, and the solid bar 34 is inserted. Twelve circular holes of the second type are formed at equal intervals on the inner peripheral side, six of which are provided with die-casting bars 36C, and the remaining are left in a space to form cooling passages. Will be retained. By stacking such silicon steel plates having two types of holes with the holes aligned, a rotor core 32 having two types of slots is provided.
Are formed.

The inside diameter of the slot into which the solid bar 34 is inserted is substantially the same as the outside diameter of the solid bar 34. The solid bar 34 is inserted by driving the solid bar 34 into this slot. The rotor core 32 into which the solid bar 34 is driven is mounted in a die (die) of a die casting machine, and the cooling passage 32 is provided.
With both ends of the six slots in which A is formed closed,
By injecting aluminum hot water, the die casting bar 36
C ′ and the cooling passage 32A are formed. The end rings 36A and 36B shown in FIG.
6C and molded integrally.

The shape of the end ring 36A is as shown in FIG. 6, the cooling passage 32A is open, and cooling air flows from the outside into the rotor core 32. Has become. Thus, the cooling passage 32
By securing A, a rise in temperature during operation of the rotor 30 can be reduced.

A die casting bar is attached to the core of the rotor core 32.
Provision of a slot of 36C may increase the magnetic flux density of the rotor core and increase the loss. However, since the magnetic flux density of the rotor core is generally sufficiently small compared to other magnetic paths, No problem. Further, as described above, a cooling vent (the cooling passage 32) is formed in the core of the rotor core 32.
By providing A), the above structure can be obtained without any magnetic influence.

According to this embodiment, since the cross-sectional area of the solid bar can be increased, the electric resistance of the rotor conductor can be reduced, and the efficiency of the induction motor can be increased.

Further, by providing a die-casting slot on the inner peripheral side of the rotor core independently of the solid bar slot, the cross-sectional area of the slot can be increased, and the occurrence of nests in the end ring and Since the bar can be prevented from being cut, the manufacturing accuracy can be improved.

As described above, the die casting bar 36C and the end rings 36A on the inner peripheral side of the rotor core 32,
By using, for example, high-strength aluminum as 36B and using copper as the solid bar 34, the rotor has high strength, is suitable for high speed, and has sufficiently low resistance of the rotor conductor. Can be. As a result, a compact, lightweight, and highly efficient induction motor can be configured. The present invention is not limited to the slot shape and the conductive material described above.

For example, when viewed as a driving motor for an electric vehicle, a high-speed rotating motor can be reduced in size and weight, and the loss of the rotor conductor can be reduced by reducing the resistance of the rotor conductor. Can be. It is the best drive motor for electric vehicles that run on the limited energy of a battery.

In addition, when the loss of the rotor is reduced, the rise in the temperature of the rotor is reduced, the life of the bearing is prolonged, the failure is reduced, and the driving distance of the battery per charge can be extended. An electric motor can be provided.

In the above embodiment, the case where the present invention is applied to a rotary motor drive has been described, but the present invention can also be applied to a linear motor drive. It can also be used for damper winding of a synchronous motor.

[0054]

According to the present invention, the efficiency of the induction motor can be improved, and the manufacturing accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an induction motor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the rotor of the induction motor according to the embodiment of the present invention, which is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of a solid bar constituting a rotor conductor of a rotor of an induction motor according to an embodiment of the present invention.

FIG. 4 is a diagram showing a cross section of a rotor of an induction motor according to another embodiment of the present invention.

FIG. 5 is a view showing a cross section of a rotor of an induction motor according to a third embodiment of the present invention.

FIG. 6 is a side view of a rotor of an induction motor according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Permanent magnet rotary electric machine 20 ... Stator 22 ... Stator iron core 24 ... Stator winding 26 ... Housing 30 ... Rotor 32 ... Rotor iron core 32A ... Cooling passage 34 ... Solid bar 36A, 36B ... End ring 36C, 36C '... Die casting bar 38 ... Shaft 46,48 ... End bracket 42,44 ... Bearing

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Suetaro Shibukawa 2520 Odaiba, Hitachinaka-city, Ibaraki Pref.

Claims (6)

[Claims] 1. A stator having a stator core wound with a stator winding, a rotor core rotatably held on an inner periphery of the stator, and die-casting on both ends of the rotor core. An end ring, and a solid bar that is inserted into a slot formed in the rotor core and is electrically connected to end rings formed at both ends of the induction motor. The end ring is inserted into a plurality of slots formed on the outer peripheral portion of the rotor core, and is inserted into a plurality of second slots formed independently of the slots on the inner peripheral side of the rotor core. An induction motor comprising a die casting bar formed integrally with the induction motor. 2. The induction motor according to claim 1, wherein the solid bar is a metal different from a metal forming the solid bar, and is covered with a metal compatible with a metal forming the end ring. An induction motor. 3. The induction motor according to claim 2, wherein the solid bar is integrally formed by inserting the solid bar into a cylindrical metal and pulling the solid bar. 4. The induction motor according to claim 2, wherein outer peripheral portions at both ends of the solid bar are plated with the metal. 5. The induction motor according to claim 1, wherein the number of slots forming the die-cast bar is smaller than the number of slots into which the solid bar is inserted. 6. The induction motor according to claim 1, further comprising a plurality of cooling passage slots formed independently of the slots on an inner peripheral side of the rotor core. .