Hybrid induction motor

A hybrid induction motor includes a motor casing; a rotational shaft rotatably coupled with the motor casing; an induction rotor rotated by being integrally coupled with the rotational shaft and having a rotor core and a conductor bar inserted in the rotor core; a stator having a hollow into which the induction rotor is inserted and installed with a certain length in a direction of the rotational shaft; a first magnetic rotor inserted between the stator and the induction rotor and coupled with the rotational shaft so as to be freely rotatable; a second magnetic rotor inserted between the stator and the induction rotor so as to be symmetrical with the first magnetic rotor and coupled with the rotational shaft so as to be freely rotatable; and a magnetic spacer inserted between the first and second magnetic rotors.

RELATED APPLICATION

The present disclosure relates to subject matter contained in priority Korean Application No. 10-2006-0025001, filed on Mar. 17, 2006, which is herein expressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hybrid induction motor having first and second magnetic rotors for improving a variable speed and driving characteristics, and more particularly, to a hybrid induction motor capable of reducing vibration and noise generated when the first and second magnetic rotors contact and as separated with each other as a motor is driven or is failed.

2. Description of the Related Art

FIG. 1is a vertical sectional view of a hybrid induction motor studied and developed by the applicant of the present invention,FIG. 2is a cross-sectional view showing the hybrid induction motor showing a state that the first and second magnetic rotors ofFIG. 1are combined while driven, andFIG. 3is a cross-sectional view of the hybrid induction motor showing a state that the first and second magnetic rotors are separated while driven.

With reference toFIGS. 1 and 2, the hybrid induction motor studied and developed by the applicant of the present invention includes a motor casing10; a rotational shaft11rotatably coupled with the motor casing10; an induction rotor20having a rotor core21integrally coupled with the rotational shaft11and rotated and a conductor bar22inserted into the rotor core21; a stator70having a hollow70ato allow the induction rotor20to be inserted therein and having a certain length in a direction of the rotational shaft11; a first magnetic rotor40inserted between the stator70and the rotor core21and coupled with the rotational shaft11so as to be freely rotatable; and a second magnetic rotor40inserted between the stator70and the induction rotor20in a symmetrical manner with the first magnetic rotor40, and coupled with the rotational shaft11so as to be freely rotatable.

The motor casing10is a container with an opening and a cover10afor covering the opening is coupled with the motor casing. A mounting recess10bwhere a bearing12that rotatably supports the rotational shaft11is installed is formed at the cover10a.

The induction rotor20includes the rotor core21formed in an annular shape with a certain length and the conductor bar22inserted into the rotor core21.

The rotor core21is a stacked body formed with a plurality of sheets stacked, and the rotational shaft11is fixed combined at the middle portion of the rotor core21. Accordingly, when the rotational shaft11is rotated, the induction rotor20is also integrally rotated.

The stator70includes a stator core71formed with a certain length and a winding coil72having a main winding and a sub-winding wound in a circumferential direction within the stator core71.

The stator core71is a stacked body formed by stacking a plurality of sheets and includes a yoke part71aformed in an annular shape with a certain width and a plurality of teeth71bextending with a certain length on an inner circumferential surface of the yoke part71a. A slot73is formed between the teeth71aand a hollow70ain which the induction rotor20is inserted is formed within the stator core71by an end face of the teeth71b.

The winding coil72is wound on the teeth71bseveral times and positioned in the slot73formed by the teeth71b. When AC power is applied to the main winding and the sub-winding at an initial stage of driving, a rotating magnetic field is generated. At this time, an induction current flows to the conductor bar22of the induction rotor20, and the induction rotor20starts to be rotated. Herein, the stator70is rotated by being slipped, and at this time, the current flowing at the sub-winding is blocked by a current blocking unit and current flows only at the main winding.

The first magnetic rotor40includes a first magnet in a cylindrical shape with a certain thickness and a first holder42formed in a cup shape and supporting the first magnet41. The first magnet41is rotatably inserted between an inner circumferential surface of the first stator70and an outer circumferential surface of the induction rotor20. A first bearing recess42ain which the first bearing42is coupled is formed at one side of the first holder42. As the rotational shaft11is coupled at the first bearing43, the first holder42can be freely rotated on the rotational shaft11.

The second magnetic rotor50includes a second magnet51installed spaced apart by a certain interval from the first magnet41and having a cylindrical shape with a certain thickness, and a second holder52formed in a cup shape and supporting the second magnet51. The second magnet51is rotatably inserted between an inner circumferential surface of the second stator80and an outer circumferential surface of the inductor rotor20. A second bearing recess52ain which the second gearing53is coupled is formed at one side of the second holder52. As the rotational shaft11is coupled with the second bearing53, the second holder53can freely rotate on the rotational shaft11.

The operation of the hybrid induction motor will now be described with reference toFIGS. 2 and 3.

When power is applied to the winding coil72of the stator70, a rotating magnetic field is formed. The thusly formed rotating magnetic field makes the first and second magnetic rotors40and50rotate at a synchronous speed.

With reference toFIG. 2, when the S pole of the first magnet41and the N pole of the second magnet51are positioned at a position as shown inFIG. 2while the motor is being driven, the S pole of the first magnet41and the N pole of the second magnet51attract each other. Then, the first magnetic rotor40moves in the direction of an arrow ‘A’0and the second magnetic rotor50moves in a direction of an arrow ‘B’, allowing the first and second magnets41and51to be attached with each other, and in this case, vibration and noise are generated.

With reference toFIG. 3, when the S pole of the first magnet41and the S pole of the second magnet51are positioned at a position as shown inFIG. 3while the motor is being driven, the S pole of the first magnet41and the S pole of the second magnet51repulses each other. Then, the first magnetic rotor40moves in a direction of an arrow ‘C’0and the second magnetic rotor50moves in a direction of an arrow ‘D’, so as to be separated. At this time, while they are separated, vibration and noise are generated.

As a result, while the motor is being driven, the fist and second magnetic rotors40and50are continuously attached and separated to generate vibration and noise, causing a problem that the operational reliability of the hybrid induction motor is degraded.

In addition, the same problem also arises when the motor is broken down as well as when the motor is driven. Namely, when a power supply to the stator70is suddenly stopped because of a failure of the motor, the first and second magnets41and51are attached or separated according to mutual positions therebetween, generating vibration and noise. Thus, the operational reliability of the hybrid induction motor is also degraded.

BRIEF DESCRIPTION OF THE INVENTION

Therefore, an object of the present invention is to provide a hybrid induction motor having first and second magnetic rotors for improving a variable speed and driving characteristics, capable of reducing vibration and noise generated when the first and second magnetic rotors are driven or failed.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a hybrid induction motor including: a motor casing; a rotational shaft rotatably coupled with the motor casing; an induction rotor rotated by being integrally coupled with the rotational shaft and having a rotor core and a conductor bar inserted in the rotor core; a stator having a hollow into which the induction rotor is inserted and installed with a certain length in a direction of the rotational shaft; a first magnetic rotor inserted between the stator and the induction rotor and coupled with the rotational shaft so as to be freely rotatable; a second magnetic rotor inserted between the stator and the induction rotor so as to be symmetrical with the first magnetic rotor and coupled with the rotational shaft so as to be freely rotatable; and a magnetic spacer inserted between the first and second magnetic rotors.

DETAILED DESCRIPTION OF THE INVENTION

The hybrid induction motor according to the exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 4is an assembled perspective view of the first and second magnetic rotors, a magnetic spacer and a rotational shaft of the hybrid induction motor according to an exemplary embodiment of the present invention,FIG. 5is a perspective view of the magnetic spacer ofFIG. 4,FIG. 6is a cross-sectional view of the hybrid induction motor showing a state that the first and second magnetic rotors ofFIG. 4are attached to the magnetic spacer during their operation, andFIG. 7is a cross-sectional view of the hybrid induction motor showing a state that the first and second magnetic rotors ofFIG. 4are separated from the magnetic spacer during their operation. The same or equivalent elements as those in the related art will be given the same reference numerals and a description for those same elements will be omitted.

With reference toFIGS. 4 and 6, a hybrid induction motor includes: a motor casing10; a rotational shaft11rotatably coupled with the motor casing10; an induction rotor20having a rotor core21integrally coupled with the rotational shaft and rotated and a conductor bar22inserted in the rotor core; a stator70having a hollow70ainto which the induction rotor20is inserted and installed with a certain length in a direction of the rotational shaft11; a first magnetic rotor40inserted between the stator70and the induction rotor20and coupled with the rotational shaft11so as to be freely rotatable; a second magnetic rotor50inserted between the stator70and the induction rotor20so as to be symmetrical with the first magnetic rotor40and coupled with the rotational shaft11so as to be freely rotatable; and a magnetic spacer100positioned between the first and second magnetic rotors40and50.

The construction and operation of the motor casing10, the induction rotor20, the first magnetic rotor40, the second magnetic rotor50and the stator are the same as the hybrid induction motor studied and developed by the applicant of the present invention as shown inFIGS. 1 to 3, so its description will be omitted and the magnetic spacer100, a core element of the present invention, will be described in detail.

With reference toFIGS. 4 and 5, the magnetic spacer100is insertedly positioned between the first and second magnets41and51. For this purpose, the magnetic spacer100includes a through hole101to allow the induction rotor20to penetrate therethrough. The through hole101has a larger diameter than that of the induction rotor20(refer toFIG. 6) so that the magnetic spacer100can be freely rotated on an outer circumferential surface of the induction rotor20.

Preferably, the magnetic spacer100has a thickness (t) of 0 5 to 1 mm to increase adhesion between the first and second magnets41and51according to results obtained by an experimentation.

The magnetic spacer100made of a material of one of iron, nickel and cobalt that can be easily magnetized or made by mixing two or more materials of them. But the present invention is not limited thereto and the magnetic spacer100can be made of any other material so long as it can be easily recognized.

The operation of the hybrid induction motor according to an exemplary embodiment of the present invention will be described as follows.

With reference toFIGS. 6 and 71when power is applied to a winding coil72of the stator70, the stator70forms a rotating magnetic field. The thusly formed rotating magnetic field makes the first and second magnetic rotors40and50rotate at a synchronous speed.

When the S pole of the first magnet41and the N pole of the second magnet51are positioned at a position as shown inFIG. 6while the motor is being driven, the S pole of the first magnet41and the N pole of the second magnet51attract each other. Then, the first magnetic rotor40moves in the direction of an arrow ‘A’ and the second magnetic rotor50moves in a direction of an arrow ‘B’, allowing the first and second magnets41and51to be attached on both sides of the magnetic spacer100. In this case, because the first and second magnets41and51are not directly attached but indirectly attached by the medium of the magnetic spacer100, the distance at which the first and second magnets41and51are attached is short to reduce vibration and noise generated by their collision, compared with the case where the magnetic spacer100is not provided. In addition, because the magnetic spacer100serves as a medium therebetween, the adhesion between the first and second magnets41and51increases, so they cannot hardly separated and thus vibration and noise caused by their separation and attachment can be reduced.

Meanwhile, when the S pole of the first magnet41and the S pole of the second magnet51are positioned at a position as shown inFIG. 7while the motor is being driven, the S pole of the first magnet41and the S pole of the second magnet51repulses each other. Then, the first magnetic rotor40moves in a direction of an arrow ‘C’0and the second magnetic rotor50moves in a direction of an arrow ‘D’, so as to be separated. In this case, because the first and second magnets41and51are not directly attached but indirectly attached by the medium of the magnetic spacer100, the distance at which the first and second magnets41and51are separated is short to reduce vibration and noise generated by their separation, compared with the case where the magnetic spacer100is not provided. In addition, since the magnetic spacer100serves as a medium therebetween, the adhesion between the first and second magnets41and51increases, while a small degree of separation is maintained between them, and thus vibration and noise caused by their separation and attachment can be reduced.

Meanwhile, when the motor suddenly stops the magnetic spacer100can reduce vibration and noise generated as the first and second magnets41and51are separated or attached. Namely, when power supply to the stator70is suddenly stopped because of the failure of the motor, vibration and noise are generated as the first and second magnets41and51are separate or attached according to their mutual positions.

In this case, because the magnetic spacer100is insertedly positioned between the first and second magnets41and51, the vibration and noise caused by the separation and attached between the first and second magnets41and51can be reduced.

As so far described, the hybrid induction motor according to the exemplary embodiment of the present invention has the advantage that because the magnetic space is positioned between the first and second magnetic rotors, the adhesion between the first and second magnetic rotors increases while a small degree of separation is maintained between the first and second magnetic rotors. Thus, whether the motor is driven or not, vibration and noise caused by their separation and contact between the first and second magnetic rotors can be reduced. Therefore, the operational reliability of the hybrid induction motor can be enhanced.