JPH06225498A - Induction motor - Google Patents

Abstract

PURPOSE:To increase an output torque by dividing a rotor into two portions at its intermediate part in the axial direction to enable inverse rotations and by enabling mutual contact between the dividing surfaces of rotor bars of the divided rotors. CONSTITUTION:A rotor 13 of a motor M is divided into two sections in the axial direction 5 at its intermediate part to enable inverse rotations and the dividing surfaces of rotor bar of the divided rotors 14, 15 are enabled to be in contact with each other. Therefore, when rotating difference is generated on rotation of divided rotors 14, 15 due to a rotating difference between right and left wheels, the dividing surfaces of rotor bar generates positional deviation while these are rotating. Under this condition, an effective value of the contact area at the dividing surfaces is reduced, a sectional area of the rotor bar of the rotor 13 as a while becomes small and a secondary resistance value of the rotor 13 as a whole becomes large. Thereby, a peak value of an output torque of a motor M shifts toward a low speed side to become a motor M having a large low speed torque. As a result, an output torque of the motor M can be increased during the running of a vehicle.

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 having a squirrel-cage rotor.

[0002]

2. Description of the Related Art Conventionally, this type of induction motor is well known as a kind of AC motor, and is disclosed in, for example, Japanese Patent Laid-Open No. 3-173.
As disclosed in Japanese Patent No. 328 or the like, an output shaft rotatably supported by a casing, and a substantially cylindrical stator having a winding arranged in a groove and concentric with the output shaft. A rotor having an outer peripheral surface concentrically and integrally attached to the output shaft in the stator concentrically with the inner peripheral surface of the stator, and a plurality of rotor bars arranged at equal intervals in the outer peripheral portion; And supplying a primary current from the outside to the coil of the stator to generate a rotating magnetic field, and the rotating magnetic field of the stator generates a secondary current flowing through the rotor bar of the rotor. The rotor is rotated by an electromagnetic force with the rotating magnetic field on the stator side.

[0003]

By the way, a DC motor is generally used as a power unit of a vehicle such as an electric vehicle, but there is an attempt to use an AC motor because of its compactness and high output. The squirrel cage induction motors have been receiving attention.

On the other hand, in general, a vehicle is provided with a differential mechanism for compensating for the difference in rotation between the left and right wheels during turning, in the middle of the drive shaft, and a differential mechanism is also required for electric vehicles and the like.

However, since this differential mechanism comprises a differential gear mechanism as an assembly of gears, its installation space is large and there is a limit to its cost reduction.

The present invention has been made in view of the above points, and an object thereof is to make good use of the structure of the above-mentioned squirrel cage induction motor when it is used as a power unit of a vehicle such as an electric vehicle. The purpose is to secure the same function without requiring a conventional differential mechanism and to increase the output torque of the electric motor when the differential function is exerted.

[0007]

In order to achieve this object, in the invention of claim 1, the rotor and the output shaft of the squirrel cage induction motor are divided into two in the axial direction, and each output shaft is connected to the wheel. When the relative rotation between the wheels occurs, the divided rotors are rotated relative to each other to obtain a differential function, and along with the relative rotation, the cross-sectional area of the rotor bar of the rotor is reduced on the divided surface so that the rotor bar is The secondary resistance is increased to increase the output torque of the electric motor, that is, the power unit of the vehicle.

That is, according to the present invention, as described above,
An output shaft rotatably supported in the casing, a substantially cylindrical stator arranged concentrically with the output shaft in the casing, and an output shaft in the stator are rotatably and integrally attached to a plurality of outer peripheral parts. It is premised on an induction motor having a rotor bar and an output shaft and a rotor arranged concentrically with each other.

The rotor and the output shaft are axially divided into two parts in the rotor middle part so that they can rotate relative to each other, and each divided output shaft is connected to the left and right wheels of the vehicle, and the rotor bar of each divided rotor is divided. Allow the surfaces to contact each other.

[0010]

With the above construction, in the first aspect of the invention, the rotor and the output shaft of the electric motor are axially divided into two in the rotor intermediate portion so that they can rotate relative to each other, and the divided output shafts are divided into left and right sides of the vehicle, respectively. Being connected to the wheels, the wheels of the vehicle can be driven by an electric motor.

When this vehicle makes a turning motion to cause a rotation difference between the left and right wheels, the divided output shafts connected to the wheels receive the rotational driving force of the corresponding rotors in response to each other, and are thus mutually separated. It will rotate relative to
The relative rotation of both split output shafts can compensate for the difference in rotation between the left and right wheels, and the motor itself can have a differential function.Therefore, a differential mechanism consisting of a differential gear mechanism is not required, and the size and cost can be reduced. Can be planned.

Further, at that time, the rotor of the electric motor is axially divided into two parts in the intermediate part thereof so as to be rotatable relative to each other, and the divided surfaces of the rotor bars of the divided rotors can contact each other. When the rotation difference between the wheels causes a rotation difference in the rotation of the split rotor, the split surfaces of the rotor bar are displaced while contacting each other. In this misaligned state of both split rotors, the effective value of the contact area on the split surface is reduced compared to the state where there is no misalignment (when there is no rotation difference of the split rotors), and The cross-sectional area of the rotor bar becomes small, and the secondary resistance value of the entire rotor increases. As a result, the peak value of the output torque of the electric motor moves to the low speed side and becomes an electric motor with a large low speed torque. Therefore, the output torque of the electric motor as a power unit can be increased when the vehicle is turning.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an induction motor M according to an embodiment of the present invention, and this motor M is used as a power unit of an electric vehicle which is a kind of vehicle. The electric motor M includes a closed cylindrical casing 1. The casing 1 includes a cylindrical stator assembly portion 2 and a pair of circles concentrically assembled to the stator assembly portion 2 so as to close openings at both ends thereof. It is composed of a plate-shaped bearing portion 3. A bearing hole 4 is opened at the center of each of the bearing portions 3, and the output shaft 5 is rotatably and axially disposed between the bearing holes 4 and 4 of the bearing portions 3 and 3 via bearings 8 and 8, respectively. It is inserted and supported immovably.

On the inner periphery of the stator assembly portion 2 of the casing 1, a substantially cylindrical stator 9 is arranged concentrically with the output shaft 5 and is assembled and fixed. A plurality of grooves (not shown) extending substantially parallel to the output shaft 5 are formed on the inner peripheral surface of the stator 9, and U, V, W three-phase coils 1 are formed in the plurality of grooves.
0 (see FIG. 4) are housed, and a rotating magnetic field is generated by externally supplying a primary current to the three-phase coils 10, 10, ... Of the stator 9.

As shown in FIG. 4, the U-, V-, and W-phase coils 10, 10, ... Are Δ-connected, and each coil 10 has a first coil 11 with a smaller number of turns and a first coil 11 with a smaller number of turns. 1
The second coil 12, which is more than the coil 11, is connected in parallel. Incidentally, as shown in FIG. 5, when the three-phase coils 10, 10, ... Are Y-connected, similarly, the first coil 11 having a small number of turns and the second coil 12 having a large number of turns may be connected in parallel.

A squirrel cage rotor 13 (rotor) is attached to the output shaft 5 in the stator 9 so as to rotate together.
The rotor 13 has a substantially cylindrical rotor core 16, and its outer peripheral surface is arranged concentrically with the inner peripheral surface of the stator 9 with a predetermined gap. A plurality of grooves 16a, 16a, extending obliquely so as to intersect with a plane passing through the axis of the output shaft 5 are formed on the outer peripheral portion of the rotor core 16, and as shown in FIG. Is a rotor bar 17 made of copper rod
Are housed, and the plurality of rotor bars 17, 17, ... Are connected to each other by an annular short-circuit ring 18, 18 at the end of the rotor core 16. Then, a three-phase AC primary current is externally supplied to each coil 10 of the stator 9 to generate a rotating magnetic field in the stator 9, and the rotating magnetic field causes a secondary current flowing through the rotor bars 17, 17 ,. Is generated, and the rotor 13 is rotated by the electromagnetic force between the secondary current on the rotor 13 side and the rotating magnetic field on the stator 9 side.

Further, the rotor 13 and the output shaft 5 are divided into two axially rotatably at the center of the rotor 13 in the axial direction. That is, the output shaft 5 is divided into a left split output shaft 6 on the left side in FIG. 1 and a right split output shaft 7 on the right side, and the split output shafts 6 and 7 are connected and supported so that they can rotate relative to each other at their opposing ends. Has been done. For example, one of the split output shafts 6 (or 7) is provided with a mounting hole 19 at the center of the opposite end of the other split output shaft 7 (or 6), while the other split output shaft 7 (or 6) A small-diameter shaft portion 20 that is fitted into the mounting hole 19 is formed in the center of the opposing end portion of the split output shaft 6 (or 7), and the small-diameter shaft portion 20 is concentrically formed in the mounting hole 19 via a bearing 21. By mounting them, the split output shafts 6 and 7 are supported so as to be rotatable relative to each other at their opposing ends. Then, as shown in FIG.
The outer end of the left split output shaft 6 (the end opposite to the side opposite the right split output shaft 7) is connected to the left wheel 23 of the electric vehicle via the joint 22, and the outer end of the right split output shaft 7 ( Ends on the side opposite to the left split output shaft 6 and on the opposite side) are connected to the right wheel 25 via joints 24, respectively.
In FIG. 3, reference numeral 26 is a vehicle body of the electric vehicle.

On the other hand, the rotor 13 is divided into a left side divided rotor 14 on the left side and a right side divided rotor 15 on the right side in FIG. 1 corresponding to the divided positions of the output shaft 5. At this time, as shown in FIG. , 15 rotor bar 17 split surface 17
a and 17a can contact each other.

Therefore, in the above embodiment, when the output shaft 5 is rotated by the operation of the electric motor M, the left and right wheels 23 and 25 connected to the output shaft 5 via the joints 22 and 24 are driven. It rotates, and as a result, an electric vehicle using the electric motor M as a power unit runs.

In this case, the rotor 13 and the output shaft 5 of the electric motor M are axially divided into two parts at the center of the rotor 13 so that they can rotate relative to each other, and the divided output shafts 6 and 7 are left and right wheels of the vehicle, respectively. Since the electric vehicles are connected to the wheels 23 and 25, when the electric vehicle turns and causes a difference in rotation between the left and right wheels 23 and 25, the split output shafts 6 and 7 connected to the wheels 23 and 25 are accordingly generated. The two rotate relative to each other while receiving the rotational driving force of the corresponding rotor 13. As a result, the relative rotation of the split output shafts 6 and 7 can compensate for the rotation difference between the left and right wheels 23 and 25, and the electric motor M itself can have a differential function, and thus the conventional differential mechanism including a differential gear mechanism. Is unnecessary, and it is possible to reduce the size and cost.

When the electric vehicle is turning, the rotor bar 17 in each of the split rotors 14 and 15 of the electric motor M is also provided.
Since the split surfaces 17a, 17a of the split rotors can contact each other, when a rotation difference occurs in the rotation of the split rotors 14, 15 due to the rotation difference between the left and right wheels 23, 25,
The rotor bars 17, 17 of the respective divided rotors 14, 15 are displaced while the divided surfaces 17a, 17a are in contact with each other. Compared to the state in which there is no positional deviation (the straight traveling state of the electric vehicle in which there is no difference in rotation between the divided rotors 14 and 15), the contact area on the divided surfaces 17a and 17a is smaller in the positional deviation state between the two divided rotors 14 and 15. The effective value decreases, the cross-sectional area of the rotor bar 17 in the entire rotor 13 becomes small, and the secondary resistance value in the entire rotor 13 increases. As a result, the peak value of the output torque of the electric motor M moves to the low speed side to become the electric motor M having a large low speed torque, and the output torque of the electric motor M can be increased when the electric vehicle turns.

By the way, generally, when the rotation speed of the electric motor is increased, the output density (output / weight) can be increased, which is advantageous as a power unit for an electric vehicle or the like. At that time, in the induction motor, the rotation speed can be increased by increasing the frequency of the input power source by using an inverter or the like. However, as the power supply frequency increases, the impedance of the coil increases in proportion to the square of the power supply frequency. Therefore, it is necessary to reduce the number of turns of the coil and reduce the inductance thereof in order to pass the necessary current.
However, if the number of coil turns is reduced in this way, the excitation current required to secure the magnetic field across the rotor and stator increases when the power supply frequency is lowered when the motor is started or at low revolutions, and can be taken out as output. This leads to a decrease in the power factor, which is a ratio.

In this embodiment, each coil 10 of the stator 9 of the electric motor M is formed by connecting the first coil 11 having a small number of turns and the second coil 12 having a large number of turns in parallel.
It is possible to increase the output torque at the time of high rotation while reducing the exciting current at the time of starting the electric motor M or at the time of low rotation.
That is, when the power supply frequency is low at the time of starting the electric motor M or at low speed, the value of the current flowing through each coil 10 is not restricted by its inductance, but is mostly restricted by the DC resistance. For this reason, current flows through both the first and second coils 11 and 12, and the electric motor M becomes a low rotation type electric motor having a large number of coil turns when viewed from the whole, and the exciting current is reduced to improve the power factor. You can

On the other hand, when the power supply frequency is increased at the time of high rotation and the like, the current value is limited by the inductance, not the resistance of the coil. Therefore, the second coil 12 having a large number of turns is used.
Almost no current flows through the first coil 11, and most of the current passes through the first coil 11 having few windings. As a result, the electric motor M functions as a high rotation type, and a required output can be secured.

Although the above embodiment is applied to an electric vehicle, the present invention can be applied to other vehicles using an induction motor as a power source.

[0026]

As described above, according to the first aspect of the present invention, when the induction motor having the squirrel cage rotor is used as the power unit of the vehicle, the rotor and the output shaft are rotatable relative to each other at the rotor intermediate portion. By dividing the output shafts into two in each direction, connecting each output shaft to the left and right wheels of the vehicle, and allowing the split surfaces of the rotor bars of each split rotor to contact each other, the motor itself has a differential function. It is possible to reduce the size and cost of the rotor, and reduce the effective value of the contact area on the split surface of the rotor bar when there is a rotation difference between the split rotors when the vehicle is turning. It is possible to increase the secondary resistance value at and to move the peak value of the output torque of the electric motor to the low speed side. And torque is increased, and inexpensive vehicle power unit for motor obtain a compact with a built-in differential function.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan view showing a state where the electric motor is connected to wheels.

FIG. 4 is an electric circuit diagram showing a coil connection state to a stator of an electric motor.

FIG. 5 is a view corresponding to FIG. 4 showing a modified example of the coil connection state to the stator.

[Explanation of symbols]

 M induction motor 1 casing 5 output shaft 6 left split output shaft 7 right split output shaft 9 stator 10 coil 13 rotor 14 left split rotor 15 right split rotor 17 rotor bar 17a split surface 23, 25 wheels

Front page continuation (72) Inventor Yasushi Kawato 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Tsutomu Shimizu 3-1-1 Shinchu, Fuchu-cho, Hiroshima Prefecture Mazda Corporation

Claims (1)

[Claims] 1. An output shaft rotatably supported by a casing, a substantially cylindrical stator arranged concentrically with the output shaft in the casing, and attached to the output shaft in the stator so as to rotate integrally. In an induction motor including a plurality of rotor bars on an outer peripheral portion thereof, the rotor being arranged concentrically with an output shaft, the rotor and the output shaft are divided into two axially rotatably relative to each other at a rotor intermediate portion, An induction motor characterized in that split output shafts are respectively connected to left and right wheels of a vehicle, and split surfaces of rotor bars of respective split rotors can contact each other.