JP2014220885A - Induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction motor capable of preventing the temperature inside a housing from being elevated by heat generation in a stator and a rotor, even when the rotor is stopped.SOLUTION: A cooling fan 5 provided on a rotation axis is supported so as to be freely rotated independently of a rotor 4 and a rotary shaft 2 via a bearing 6. The cooling fan 5 is formed from a substantially cylindrical brake winding part 9 and a disc-shaped fan part 8 in which a plurality of blades 7 are formed. The brake winding part 9 is disposed oppositely to a stator 3. When a three-phase alternating current is given to a coil 15 of the stator 3, a magnetic flux of a generated revolving magnetic field crosses each of conductors in the brake winding part 9, such that an induction current flows into the conductor. Running torque is generated by an interaction of this current and the magnetic flux, and the brake winding part 9 is rotated in the same direction as the revolving magnetic field. The fan part 8 integrally fixed to the brake winding part 9 is rotated, ambient air is agitated, and the stator 3 and the rotor 4 are cooled.

Description

  The present invention relates to an induction motor used in a vehicle, and more particularly to an induction motor having a cooling structure that suppresses an internal temperature rise.

  2. Description of the Related Art Conventionally, high-output large-current induction motors are used as motors for vehicle drive devices (for example, electric four-wheel drive devices). The operation of this induction motor is to generate a magnetic flux by passing a current through a primary coil arranged in the stator. This magnetic flux generates an induced current on the rotor side, and generates a rotating torque by the interaction between the magnetic flux and the induced current. It is something to be made. This type of motor, for example, requires high torque (large current) even when the motor is stopped when the vehicle starts, and at this time, the stator and rotor of the motor generate heat, and thus cooling is necessary. And in order to prevent the temperature rise inside the motor as described above, there is one provided with means for cooling the stator and the rotor by convection of air by an impeller (fan) provided at the end of the rotor (for example, Patent Document 1).

JP-A-5-103443

  However, in the above configuration, when the rotor rotates, the fan provided at the end of the rotor rotates and agitates the surrounding air to cool it, but the fan does not rotate when the rotor is not constrained to rotate. . Even when the rotor is not rotating, a current flows through the stator winding, and an induced (secondary) current also flows through the rotor. As a result, the stator and the rotor generate heat, and the temperature inside the motor rises. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an induction motor that can suppress temperature rise in the housing due to heat generation of the stator and the rotor even when the rotor is stopped.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a stator that is housed in a housing and generates a rotating magnetic field, a rotor that is fixed to a rotating shaft and rotates within the stator, and a radially inner side of the stator. A cooling fan that is disposed adjacent to the rotor, is rotatably supported on the rotation axis via a bearing, and rotates independently of the rotation axis, and the cooling fan is substantially cylindrical. And a fan winding part having a plurality of blades arranged radially on the side surface, and a braking coil part formed on the outer periphery and arranged opposite to the stator.

  According to the above configuration, since the cooling fan including the brake winding portion and the fan portion that can be freely rotated independently of the rotor is provided coaxially with the rotation shaft by using the stator, the cooling fan is separated from the stator. It can be rotated by the generated rotating magnetic field. Thereby, air can be stirred by rotation of a fan part, the heat_generation | fever of a stator and a rotor can be suppressed and the inside of a housing can be cooled.

  The invention according to claim 2 is the induction motor according to claim 1, wherein the cooling fan supplies the rotating magnetic field from the stator even when the rotating shaft is stopped. The gist is that an induced current is generated in the braking winding portion and is driven to rotate.

  According to the above configuration, since the rotating magnetic field is continuously supplied from the stator even when the rotor is stopped, the rotating torque can be generated in the braking winding portion. Thereby, a cooling fan can be rotationally driven. As a result, temperature rise inside the housing due to heat generated by the stator and the rotor can be suppressed even when the rotor is stopped.

  ADVANTAGE OF THE INVENTION According to this invention, the induction motor which can suppress the temperature rise inside a housing by the heat_generation | fever of a stator and a rotor can be provided even when a rotor stops.

The longitudinal section showing the schematic structure of the induction motor concerning one embodiment of the present invention. The perspective view which shows the rotor part of FIG. The front view of the fan part of a cooling fan. The perspective view which shows the braking coil part of a cooling fan.

Next, an induction motor mounted on a vehicle according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a schematic configuration of an induction motor 1 according to an embodiment of the present invention. As the induction motor 1, for example, a cage type induction motor is used. A stator 3 is fixed to a housing (motor case) 12 of the induction motor 1, and a plurality of slots (not shown) are provided on the inner periphery of the stator 3, and coils (windings) 15 are arranged in the respective slots. Has been. A pair of bearings 13 and 13 are attached to the central portion of the housing 12 and rotatably support the rotary shaft 2 at both ends. A rotor 4 incorporating a squirrel-cage winding is fixed to the rotating shaft 2. The cage winding is composed of a plurality of rotor bars (secondary conductors) 11 and a pair of end rings (short-circuited rings) 10. Further, a cooling rotor fan 14 is attached to the front side (left in the figure) of the rotor 4 in the axial direction.

  Here, the operation of the induction motor 1 will be described with reference to FIG. When a three-phase alternating current is applied to the coil 15 of the stator 3, a rotating magnetic field is generated in the circumferential direction. A speed (induced) electromotive force is generated in the rotor bar 11 when the magnetic flux of the rotating magnetic field crosses each rotor bar 11 of the rotor 4. An induced current flows in the rotor bar 11 due to the speed electromotive force, and torque is generated by the interaction between the current and the magnetic flux, thereby rotating the rotor 4 in the same direction as the rotating magnetic field. Since the rotational speed of the rotor 4 at this time has slip in relation to the generated torque, it is lower than the speed of the rotating magnetic field on the stator 3 side.

  The force generated by the interaction between the current and the magnetic flux in the rotor bar 11 is the product of the magnetic flux and the current due to the speed electromotive force in accordance with Fleming's left-hand rule. Since this generated force is generated in a direction perpendicular to the magnetic flux directed in the radial direction (tangential direction of the rotor 4), the generated force is generated in a direction in which the rotor 4 is rotated. Therefore, the force generated in each rotor bar 11 is effectively used as the torque of the rotor 4.

  Next, the structure of the cooling fan 5 will be described with reference to FIG. A cooling fan 5 provided adjacent to the rotor 4 on the rotational axis inside the radial direction of the stator 3 is rotatably supported by a bearing (bearing) 6 independently of the rotor 4 and the rotational shaft 2. Yes. The cooling fan 5 is a disk-shaped fan in which a braking winding portion 9 made of a cylindrical conductor and a plurality of blades 7 arranged radially on the rear side (right side in the drawing) and extending radially are formed. Part 8. The braking winding portion 9 is a metal squirrel-cage winding or a conductor sleeve, and is disposed facing the stator 3.

  Here, when a three-phase alternating current is applied to the coil 15 of the stator 3, a rotating magnetic field is generated in the circumferential direction. When the magnetic flux of the rotating magnetic field crosses each conductor of the braking winding portion 9, a speed electromotive force is generated in the conductor, and an induced current flows in the conductor by the speed electromotive force. Then, a rotational torque is generated by the interaction between the current and the magnetic flux, and the braking winding portion 9 is rotated in the same direction as the rotating magnetic field. At this time, the fan unit 8 fixed integrally with the braking winding unit 9 rotates. Thus, when the rotor 4 is rotating, the surrounding air is agitated by the rotation of the rotor fan 14 and the cooling fan 5, the heat generation of the stator 3 and the rotor 4 is suppressed, and the interior of the housing 12 can be cooled. it can.

  Even when the rotor 4 is stopped, the cooling fan 5 can rotate as long as a rotating magnetic field is generated by the shared stator 3. As a result, the rotation of the cooling fan 5 makes it possible to agitate the air and suppress an increase in temperature inside the housing 12 due to heat generated by the stator 3 and the rotor 4.

  FIG. 2 is a perspective view showing a portion of the rotor 4 of FIG. As shown in FIG. 2, the rotor 4 that outputs the torque of the induction motor 1 (see FIG. 1) is fixed to the rotating shaft 2, and the cooling fan 5 is independent of the rotating shaft 2 and the rotor 4 on the rotating axis. It is arranged so that it can rotate. The rotor fan 14 composed of a plurality of cooling blades is attached to the front side surface (left side in the figure) of the rotor 4 in the axial direction, and rotates together with the rotor 4 and the rotating shaft 2.

  Next, FIGS. 3A and 3B are front views of the fan portion 8 of the cooling fan 5. The fan portion 8 is made of a disk-shaped metal or resin, and extends radially from the center of rotation in the radial direction, as shown in FIG. 3 (a) or a plurality of curved blades shown in FIG. 3 (b). 7 is arranged.

  4A and 4B are perspective views of the braking winding portion 9 of the cooling fan 5. FIG. The braking winding portion 9 is made of a metal material (for example, copper or aluminum), and is formed in a squirrel-cage winding shown in FIG. 4 (a) or a cylindrical shape (sleeve) shown in FIG. 4 (b). ing. As shown in FIG. 4A, the cage-type braking winding portion 9 is configured by arranging a plurality of conductor bars in the circumferential direction and connecting both ends to a pair of short-circuited rings.

  Next, the operation and effect of the induction motor 1 according to the embodiment of the present invention configured as described above will be described.

  According to the configuration of the present embodiment, the cooling fan 5 provided adjacent to the rotor 4 on the rotational axis inside the radial direction of the stator 3 is independent of the rotor 4 and the rotational shaft 2 by the bearing 6. It is supported rotatably. The cooling fan 5 includes a substantially cylindrical braking winding portion 9 and a disk-shaped fan portion 8 formed on a rear side surface in the axial direction and formed with a plurality of blades 7 extending radially in the radial direction. . The braking winding portion 9 is a metal squirrel-cage winding or a conductor sleeve, and is disposed facing the stator 3. When a three-phase alternating current is applied to the coil 15 of the stator 3, a rotating magnetic field is generated. When the magnetic flux of this rotating magnetic field crosses each conductor of the braking winding portion 9, a speed electromotive force is generated in the conductor. Due to this speed electromotive force, an induced current flows in the conductor, and a rotational torque is generated by the interaction between the current and the magnetic flux to rotate the braking winding portion 9 in the same direction as the rotating magnetic field. Then, the fan unit 8 fixed integrally with the braking winding unit 9 rotates. Thus, when the rotor 4 is rotating, the surrounding air is agitated by the rotation of the rotor fan 14 and the cooling fan 5, the heat generation of the stator 3 and the rotor 4 is suppressed, and the interior of the housing 12 can be cooled. it can.

  Further, even when the rotor 4 is stopped, the fan unit 8 provided in the cooling fan 5 can be rotated as long as the rotating magnetic field is generated by the shared stator 3. It is possible to suppress an increase in temperature inside the housing 12 due to heat generated by the stator 3 and the rotor 4 by the flow of the agitated air. As a result, it is possible to suppress an increase in temperature of the induction motor 1 due to heat generation of the stator 3 and the rotor 4 when the induction motor 1 is stopped when the vehicle starts or climbs. Further, since the cooling fan 5 can be configured by sharing the stator 3, the number of parts of the cooling fan 5 can be reduced and the motor size can be reduced.

  As described above, according to the embodiment of the present invention, it is possible to provide an induction motor that can suppress a temperature rise inside the housing due to heat generation of the stator and the rotor even when the rotor is stopped.

  As mentioned above, although embodiment which concerns on this invention was described, this invention can also be implemented with another form.

  In the above embodiment, the inside of the induction motor 1 is cooled by stirring the air. However, the present invention is not limited to this, and a method of cooling the oil (oil) stored in the lower part of the housing 12 using an impeller is cooled. May be applied. In this case, it is set as the structure which has the impeller for oil lifting which can be freely rotated with respect to the rotor 4 and the rotating shaft 2 on the same axis as the rotating shaft 2.

  In the above embodiment, the example in which the induction motor 1 is applied to a vehicle drive device such as an electric four-wheel drive device has been described. However, the present invention is not limited to this, and the present invention can also be applied to a device using another induction motor.

1: induction motor, 2: rotating shaft, 3: stator, 4: rotor, 5: cooling fan,
6, 13: bearing (bearing), 7: blade, 8: fan part, 9: braking winding part,
10: End ring, 11: Rotor bar, 12: Housing, 14: Rotor fan,
15: Coil

Claims (2)

A stator that is housed in a housing and generates a rotating magnetic field;
A rotor fixed to a rotating shaft and rotating in the stator;
A cooling fan disposed radially inward of the stator, adjacent to the rotor, rotatably supported via a bearing on the rotation axis, and rotating independently of the rotation axis;
The cooling fan is formed in a substantially cylindrical shape, and includes a braking winding portion disposed on the outer periphery so as to face the stator, and a fan portion having a plurality of blades radially disposed on a side surface. Induction motor. The induction motor according to claim 1,
The cooling fan is driven to rotate by generating an induced current in the braking winding portion by supplying a rotating magnetic field from the stator even when the rotating shaft is stopped. Induction motor.

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