JPH06141401A - Driver for motor operated vehicle - Google Patents

Abstract

PURPOSE:To provide a driver for a motor operated vehicle in which a large torque is generated in a low speed range and a high speed rotation is performed. CONSTITUTION:A rotary shaft 7 is so thrustfully supported as to generate an axial relative displacement between a rotor 3 and a stator 2 of a DC motor. A centrifugal governor mechanism 10 for so driving the shaft 7 as to reduce an opposed area between a rotor pole 16 and a stator pole 13 upon rising of a rotating speed of a wheel 9 is provided. Generated torque is increased at the time of a low speed to increase a maximum rotating speed at the time of a high speed by regulating an effective magnetic flux amount crossing an armature winding 12 in response to a vehicle speed by the mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for an electric vehicle which uses a DC electric motor as a drive source to rotationally drive the wheels of the vehicle.

[0002]

2. Description of the Related Art A drive device for an electric vehicle is known in which a DC motor driven by a DC power source such as a battery mounted on a vehicle is used as a drive source to rotationally drive wheels of the vehicle.

As a conventional drive device of this type, there is a drive device used in an electric vehicle described in, for example, Japanese Patent Application Laid-Open No. 3-128789. In this drive device, the rotation of the electric motor is transmitted to the wheels via a transmission mechanism having an automatic centrifugal clutch and a belt type automatic transmission, so that the rotation of the electric motor in a predetermined range near the rotational speed at which the efficiency of the electric motor is maximized. The number of wheels is automatically changed while maintaining the number,
The motor load is reduced when the wheels rotate at low speeds.

A wheel-in motor in which a driving electric motor is built into a wheel has been reported as being developed for an electric vehicle (1992, Motor Technology Symposium "Electric Automatic Wheel-in Motor"). This motor is a brushless DC motor with an outer rotor structure in which the rotor that constitutes the permanent magnet field rotates outside the stator that has the armature windings. It is attached, and its drive current is controlled by a motor controller and an inverter.

[0005]

A drive device for an electric vehicle requires a large torque to be generated when the vehicle starts at a low speed and runs at a low speed. Further, during steady running on level ground, the generated torque may be relatively small, but high-speed operation is required.

Generally, in a DC motor, the applied voltage to the armature winding is V, the rotational speed is N, the number of turns of the armature winding is n, the magnetic flux interlinking with the armature winding is φ, and the armature current is i. ,
The winding resistance is R, the generated torque is T, the comparison constants are K1, K
2 and K3, V = K1 Nnφ + Ri and T = K2 iφ (1) are established, and the output P and efficiency η are P = K3 NT and η = P / Vi, respectively. The characteristics of the output P and the generated torque T with respect to the rotation speed N of the electric motor are as follows:
Depends on

FIG. 8 shows the relationship between the rotational speed N of the motor and the output P and the generated torque T when the magnitude of the interlinking magnetic flux φ of the armature winding is φ1 and φ2 (φ1> φ2), respectively. (In the case of φ2, the efficiency η is also shown.)
As can be seen from the figure, if the interlinkage magnetic flux of the armature winding is selected to be a large value φ1, the generated torque in the low speed range can be increased, but high speed rotation cannot be obtained, and conversely the required torque is required in the high speed range. If the interlinkage magnetic flux is selected to be a small value φ2 so that the generated torque can be obtained, a large generated torque cannot be obtained in the low speed range.

The conventional drive device used in the electric vehicle described in Japanese Patent Application Laid-Open No. 3-128789 operates while maintaining a rotational speed within a predetermined range near the rotational speed at which the efficiency of the electric motor is maximized. Therefore, the efficiency of the electric motor is good, and since the wheels are driven through the belt type automatic transmission, a large torque can be generated in the wheels at low speed of the vehicle, but the efficiency is reduced due to the transmission mechanism. There was a problem. Further, in this drive device, since an automatic transmission is required, it is unavoidable that the cost becomes high.

Next, in a conventional drive device in which a driving electric motor is built in a wheel, the electric wheel directly drives the electric motor, so that the transmission efficiency is good, but if a required generated torque is obtained even in a low speed range, the electric motor having a large output can be obtained. There is a problem that the electric motor becomes large in size. Further, in this conventional drive device, it is possible to control up to the rotation speed region exceeding the rated rotation speed by performing the field weakening control using the control circuit, but in the rotation speed region exceeding the rated rotation speed, the efficiency is reduced. There was a problem that the drive current of the electric motor became significantly worse and became larger than that in the steady state.

It is an object of the present invention to obtain a large generated torque in a low speed range without using an automatic speed change mechanism or to increase the size of an electric motor, and also to enable high speed operation. To provide a drive device for a vehicle.

[0011]

DISCLOSURE OF THE INVENTION The present invention is a drive device for an electric vehicle for rotatably driving the wheels of a vehicle by using a DC electric motor as a drive source. In the present invention, in order to achieve the above object, A magnetic flux adjusting means for adjusting an effective magnetic flux amount interlinking with the armature winding is provided.

When a DC motor having a structure in which the rotor magnetic poles and the stator magnetic poles face each other in the radial direction is used,
The magnetic flux adjusting means is constituted by a thrust mechanism that causes relative displacement in the axial direction between the rotor and the stator of the electric motor so as to change the facing area between the rotor magnetic pole and the stator magnetic pole of the electric motor. be able to.

The thrust mechanism may be composed of a centrifugal governor mechanism that drives the rotating shaft so as to reduce the facing area between the rotor magnetic pole and the stator magnetic pole as the rotational speed of the wheel increases. In this case, the rotating shaft of the DC electric motor is coupled to the wheel in a state where axial displacement is allowed between the rotating shaft of the rotor and the wheel.

The thrust mechanism is also controlled by the output signal of the speed detecting means for detecting the rotation speed of the electric motor so as to decrease the facing area between the rotor magnetic pole and the stator magnetic pole as the rotation speed increases. It can also be configured by an actuator that displaces the stator in the axial direction.

The thrust mechanism also includes a manual operating member connected to the stator of the electric motor, and a fixing of the electric motor so that the facing area between the rotor magnetic pole and the stator magnetic pole of the electric motor is changed by operating the manual operating member. It can also be configured by a manual operation mechanism that displaces the child in the axial direction.

When an electric motor having a structure in which a stator magnetic pole and a rotor magnetic pole oppose each other in the axial direction is used, the rotor of the electric motor is changed so as to change the gap between the rotor magnetic pole and the stator magnetic pole. The magnetic flux adjusting means can be configured by a thrust mechanism that causes relative displacement in the axial direction between the stator and the stator.

[0017]

When the effective magnetic flux amount interlinking with the armature winding of the DC electric motor for rotating the wheels of the vehicle is adjusted by the magnetic flux adjusting means, the rotational speed output characteristic of the electric motor is changed according to the magnitude of the effective magnetic flux amount. Can be adjusted, the generated torque can be increased at low speed, and the maximum attainable rotational speed can be increased at high speed.

When a DC electric motor having a structure in which the stator magnetic poles and the rotor magnetic poles face each other in the radial direction is used, a relative displacement in the axial direction is generated between the rotor and the stator of the electric motor. When a thrust mechanism is provided and the facing area between the rotor magnetic pole and the stator magnetic pole is changed by the thrust mechanism, the effective magnetic flux amount linked to the armature winding is adjusted according to the size of the facing area. You can

If the thrust mechanism is constituted by the centrifugal governor mechanism that drives the rotating shaft so as to reduce the facing area between the rotor magnetic poles and the stator magnetic poles as the rotational speed of the wheel increases, the armature will increase as the rotational speed increases. The effective magnetic flux amount can be adjusted so that the effective magnetic flux amount interlinking the winding decreases. Therefore, at low speeds, the effective magnetic flux can be increased to increase the torque generated by the motor, and as the rotational speed increases, the effective magnetic flux can be decreased to increase the maximum attainable rotational speed. It is possible to operate the electric motor near the maximum output.

Even when the thrust mechanism is constituted by an actuator that displaces the stator in the axial direction so as to reduce the facing area between the rotor magnetic pole and the stator magnetic pole as the rotational speed of the electric motor increases, the armature winding is also formed. By adjusting the effective magnetic flux amount so that the effective magnetic flux amount interlinking the line decreases as the rotation speed increases, the generated torque is increased in the low speed region and the maximum attainable rotational speed is increased in the high speed region. can do.

When the manual operation mechanism for axially displacing the stator of the electric motor is used as the thrust mechanism so as to change the facing area between the rotor magnetic pole and the stator magnetic pole of the electric motor, the rotational speed of the electric motor or the rotation speed of the electric motor is changed. The interlinkage magnetic flux amount of the armature winding can be adjusted by manual operation according to the vehicle speed corresponding to the speed.

When a DC electric motor having a structure in which the stator magnetic pole and the rotor magnetic pole face each other in the axial direction is used, the rotor of the electric motor and the rotor of the electric motor are changed so as to change the gap between the rotor magnetic pole and the stator magnetic pole. When the magnetic flux adjusting means is configured by a thrust mechanism that causes relative displacement in the axial direction with the stator, the thrust mechanism changes the gap between the rotor magnetic pole and the stator magnetic pole. As a result, the magnetic resistance of the gap can be changed to change the amount of effective magnetic flux linked to the armature winding.

[0023]

FIG. 1 shows the structure of a first embodiment of the present invention. In this embodiment, a rotary mechanism of a rotor of an electric motor is axially displaced by a thrust mechanism composed of a centrifugal governor mechanism. The amount of effective magnetic flux interlinking with the armature winding is adjusted by decreasing the facing area between the stator magnetic pole and the rotor magnetic pole that face each other in the radial direction as the wheel rotation speed increases.

In the figure, 1 is a DC electric motor consisting of a stator 2 and a rotor 3, 4 is a motor housing for accommodating the electric motor 1, consisting of a casing 5 and a cover 6, and 7
Is a rotating shaft of the rotor 3, 8 is a bearing for supporting the rotating shaft 7 in the casing 5, 9 is a wheel, and 10 is a centrifugal governor mechanism.

The DC motor 1 in this example is a brushless motor having an outer rotor structure, and the stator 2 is composed of an annular yoke portion 3 to
The stator core 11 is formed by radially projecting n (n is an integer 4 for example) salient pole portions, and coils wound around each salient pole portion of the stator core are three-phase connected. Armature winding 12
And the outer peripheral end of each salient pole portion is the stator magnetic pole 13. The three-phase output terminal of the armature winding 12 is connected to the output terminal of the inverter circuit described later. Rotor 3
Is composed of a substantially cup-shaped flywheel 14 with a permanent magnet 15 attached to the inner circumference of the peripheral wall portion. The permanent magnet 15 is magnetized in the radial direction to form a 2n-pole rotor magnetic pole 16 that faces the stator magnetic pole 13 in the radial direction. A boss 17 is provided in the center of the bottom wall of the flywheel 14,
The boss 17 is fitted to one end of the rotary shaft 7, and the rotor 3 is attached to the rotary shaft 7.

The casing 5 is made of a light alloy or the like,
It has a cup-shaped portion 18 and a bearing support portion 19, and the rotating shaft 7 is supported by a bearing 8 fitted in the bearing support portion 19. The casing 5 is fixed to a vehicle body (not shown).

The cover 6 is made of a light alloy or the like, and has a cup-shaped portion 20 and a stator mounting portion 21 provided at the center of the bottom wall of the cup-shaped portion. The stator core 11 is attached by screws 22. The casing 5 and the cover 6 are coupled to each other by screws (not shown) in a state where the opening sides of the cup-shaped portions 18 and 20 are butted against each other, and the DC motor 1 is covered by both the cup portions 18 and 20. It is in a state.

In order to detect the rotational angular position of the magnetic poles of the rotor 3, the rotor position detecting magnet 23 fixed to the outer periphery of the boss 17 of the rotor 3 and the ring shape of the stator core 11 surrounding the magnet 23 are provided. Three rotor position sensors 24, which are Hall elements and are installed at 120 ° intervals, are provided in the section.

The bearing 8 is composed of two ball bearings 25 and a sleeve 26 arranged therebetween, and supports the rotary shaft 7 rotatably and slidably in the axial direction.

The wheel 9 comprises a rim 27 and a tire 28 mounted on the outer periphery of the rim. A cylindrical portion 29 is fixed to the center of the rim 27, and the cylindrical portion 29 is fitted to the rotary shaft 7 via a spline 30. This allows
The rotary shaft 7 and the wheel 9 are coupled to each other in a state where only the axial displacement is allowed between the rotary shaft 7 and the wheel 9. On the surface of the rim 27 on the bearing 8 side, a mudguard 31 formed in a cup shape so as to surround the cylindrical portion 29 is fixed, and on the surface of the rim 27 opposite to the mudguard 31, a centrifugal governor is provided. A governor cover 32 is attached so as to surround the mechanism 10.

The centrifugal cabana mechanism 10 is rotatably supported near the central portion of the rim 27 of the wheel, which is fixed to the flange 33 fixed to the position near the other end of the rotary shaft 7 and close to the flange 33. Then, when a centrifugal force is applied, a pair of centrifugal weights 34 that press one surface of the collar portion 33 to displace the rotary shaft 7 in the direction of the arrow shown in the figure and the other surface of the collar portion 29 are elastically pressed. A spring 35 for urging the rotating shaft 7 in the direction opposite to the arrow direction shown.
It is composed of and.

When the centrifugal governor mechanism 10 causes axial displacement between the rotary shaft 7 and the wheel 9, the facing area between the stator magnetic pole 13 and the rotor magnetic pole 16 changes, and the armature winding is changed. The effective magnetic flux amount φ linked to 12 changes. In the range where the rotation speed N of the wheels 9 is equal to or lower than the predetermined rotation speed NL, the axial center position of the rotor magnetic pole 16 substantially coincides with the axial center position of the stator magnetic pole 13 (x = 0 in FIG. 1). The axial displacement of the rotary shaft 7 is restricted so as to be maintained in the state (1). In this state, the interlinkage magnetic flux amount φ of the armature winding is approximately the maximum value φL. Wheel 9
When the rotation speed N of the rotary shaft 7 increases above a predetermined rotation speed NL, the governor mechanism 10 displaces the rotary shaft 7 in the direction of the arrow as shown in FIG. Along with this, the facing area between the stator magnetic pole 13 and the rotor magnetic pole 16 decreases, and the interlinkage magnetic flux amount φ of the armature winding 12 decreases. When the rotation speed further increases and reaches the predetermined rotation speed NH, and the flux linkage amount φ of the armature winding decreases to φH,
The displacement amount of the rotating shaft 7 is regulated so that the rotating shaft 7 is not displaced in the direction of the arrow shown in the figure even if the rotating speed N further increases.

FIG. 2 shows the above relationship. The right half of FIG. 2A shows the relationship between the rotational speed N of the wheel 9 and the axial displacement x of the rotary shaft 7, and FIG. The left half of (A) shows the relationship between the axial displacement x of the rotary shaft 7 and the flux linkage φ of the armature winding 12. From these relationships, the relationship between the rotation speed N of the wheel 9 (and therefore the rotation speed of the electric motor 1) and the interlinkage magnetic flux amount φ of the armature winding is calculated.
As shown in. The relationship between the rotational speed N and the amount of interlinkage magnetic flux φ of the armature winding is such that the output P of the electric motor 1 becomes almost the maximum value in the section between the predetermined rotational speeds NL and NH. 1 and the characteristics of the centrifugal governor mechanism 10 are selected.

FIG. 3 shows a control system for controlling the rotation speed of the DC motor 1, and a known system can be used as this control system. In the figure, 36 is an accelerator grip of a steering wheel of a vehicle, and 37 is an accelerator grip 36.
A potentiometer in which a movable contact is connected to the movable contact and a DC voltage is applied to both ends of the potentiometer 37. The signal obtained between the movable contact of the potentiometer 37 and the installation (accelerator grip position detection signal) and the rotor position sensor 24 detect the signal. The phase signal of the rotor 3 and the phase signal of the rotor 3 are input to the controller 38. The controller 38 has a microcomputer, determines the duty factor of the current to be passed through the electric motor 1 based on the position detection signal obtained from the potentiometer 37 and the output signal of the vehicle speed sensor (not shown), and also determines the rotor position sensor. The phase of the alternating magnetic field in the armature winding 12 is determined based on the output signal of 24, and a switching signal representing the duty factor and phase of each armature winding 12 is given to the drive circuit 39.

In order to prevent a large current from flowing through the electric motor 1 when the vehicle starts, an output signal of an electric motor current detection circuit (not shown) is input to the controller 38, which causes the drive current of the electric motor to start. The duty factor is controlled so as not to become excessive.

The drive circuit 39 has a gate drive circuit 40 and a switching circuit 41. The gate drive circuit 40 is connected to the controller 38, and the switching circuit 41 is connected to the armature winding 12 of each phase of the electric motor 1. The switching circuit 41 is a circuit in which three pairs of FETs (field effect transistors) 42 connected in series are connected in parallel between a battery 43 and a ground.
A diode 44 is provided between each of the two sources and drains. The gate of each FET 42 is connected to the gate drive circuit 40, and the source / drain connection part of each pair of FETs is connected to the input terminal of the armature winding 12 of each phase.

The drive circuit 39 turns on each FET 42 based on the switching signal output from the controller 38.
By performing the off control, a drive current that causes an alternating magnetic field is passed through the armature winding 12 of the electric motor 1, and the magnitude of the drive current is changed according to the rotational position of the accelerator grip 36.

FIG. 4 is a schematic diagram for explaining the output characteristics of the DC motor 1 obtained in this embodiment when the duty factor is 100%. The left half of FIG. 4 is the rotation speed N of the motor 1. The relationship (see FIG. 2 (B)) between the magnetic flux adjusting means (the thrust mechanism including the centrifugal governor mechanism 10) and the interlinkage magnetic flux amount φ of the armature winding 12 is shown, and the right half of the same figure is shown. Is the rotation speed N of the electric motor 1 and the output P of the electric motor.
And the generated torque T.

In FIG. 4, the curve P (φL shown by the broken line
), P (φ1), (φ2), and P (φH) are the flux linkages φ of the armature winding 12 at constant values of φL, φ1, φ2, and φH (φL>φ1>φ2> φH), respectively. The output P of the electric motor 1 when it is maintained is shown, and these output curves show that the rotational speeds N are NL, N1, N2 and NH (NL <
When N1 <N2 <NH, the characteristic is such that the maximum output is Pm.

The straight line T (φ
L), T (φ1), T (φ2) and T (φH) are generated by the motor 1 when the interlinkage flux amount φ of the armature winding 12 is a constant value of φL, φ1, φ2 and φH. The torque T is shown. In the present embodiment, as shown in the left half of FIG. 4, the interlinkage magnetic flux amount φ of the armature winding 12 is equal to the rotation speed N.
Is held at a constant value .phi.L in a region where N.sub.L is less than NL, and is held at a constant value .phi.H in a region where the rotational speed N is above NH.
In the area between the rotation speeds NL and NH, the rotation speed N
Is increased to NL → N1 → N2 → NH, and the flux linkage amount φ is adjusted to decrease to φL → φ1 φ2 → φH. Therefore, the output P of the electric motor 1 changes along the curve P (φL) in the region where the rotation speed is NL or less as shown by the solid line in the right half of the figure, and the rotation speed changes from NL to NH. In the region between them, the value is maintained at a value near the substantially constant maximum output Pm. In addition, in the region where the rotation speed is NH or higher, the characteristic changes along the curve P (φH). Similarly, the torque T generated by the generator 1 is the straight line T in the right half of FIG.
(ΦL), T (φ1), T (φ2) and T (φH) will change along the characteristic curve shown by the solid line. Therefore, as can be seen from the figure, a large generated torque can be obtained in the low speed range, and a characteristic capable of high speed rotation can be obtained.

In FIG. 5, the electric motor 1 has a duty factor of 1
FIG. 6 is a schematic diagram for explaining the vehicle speeds obtained by the drive device of the present embodiment when the vehicle is operated at 00% and when traveling on level ground where the traveling load of the vehicle is relatively light, and during climbing on a large traveling load.

In the figure, the curve P (φL
) And P (φH) correspond to the output characteristics of the motor shown by the same symbols in FIG. 4, and the vehicle speed V and the output P of the motor when the interlinkage magnetic flux amount φ of the armature winding is a constant value φL and φH, respectively. Shows the relationship with. In FIG. 5, the curve P shown by the solid line is the output characteristic of the electric motor 1 obtained in this embodiment. Curves L1 and L2 indicated by chain lines in the figure are the vehicle speed V and the traveling load L when traveling on a level ground and climbing a slope, respectively.
It shows the relationship with.

In FIG. 5, the vehicle speed obtained by the drive unit is obtained as the vehicle speed at the intersection of the output characteristic curve of the electric motor and the running load curve. As can be seen from the figure, in the drive system of this embodiment, the vehicle speed when traveling on level ground is V1 (V1H).
The vehicle speed when climbing is V2. On the other hand, the interlinkage magnetic flux φ of the armature winding is constant values φL and φH, respectively.
When the vehicle travels on a flat ground, the vehicle speeds are V1L and V1H (V1), and the vehicle speeds when climbing are V2L and V2H, respectively. Large value of the flux linkage of the armature winding φL
If (Constant) is selected, the traveling characteristics when climbing are good, but high-speed traveling is not possible when traveling on level ground, and conversely, if the value of the flux linkage of the armature winding is set to a small value φH (Constant), it will be Although it is possible to drive at high speed, the traveling characteristics when climbing a slope will deteriorate.

On the other hand, in the case of the drive device of this embodiment, good traveling characteristics can be obtained both when traveling on a level ground and when climbing a slope.

FIG. 6 shows the structure of the second embodiment of the present invention. In this embodiment, the DC motor has a structure in which the stator poles and the rotor poles face each other in the radial direction, and the stator is The amount of interlinkage magnetic flux of the armature winding is adjusted by displacing the stator magnetic poles and the rotor magnetic poles in the axial direction to change the facing area of the stator magnetic poles and the rotor magnetic poles according to the rotation speed of the electric motor. Corresponding parts equivalent to those in FIG.

In FIG. 6, the rotary shaft 7 is composed of two ball bearings 2 fitted in the bearing support portion 19 of the casing 5.
A rotor 3 is rotatably supported by 5, and a rotor 3 is attached to one end of the rotary shaft 7. A cylindrical portion 29 provided at the center of the rim 27 of the wheel 9 is fitted to the other end of the rotating shaft 7 and the wheel 9 is fixed to the rotating shaft 7 by a nut 45.

Reference numeral 46 denotes a stator mounting member, which has a cylindrical portion 47 extending in the axial direction and a flange portion 48 provided on one end side of the cylindrical portion 47. The columnar portion 47 is supported by a sliding bearing 49 fitted in a bearing portion provided in the central portion of the bottom wall of the cup-shaped portion 20 of the cover 6,
The stator 2 is attached to the flange portion 48 with screws 22. The stator mounting member 46 is supported by the sliding bearing 49 in a state where only the axial displacement is allowed between the stator mounting member 46 and the cover 6. Between the bottom wall portion of the cup-shaped portion 20 of the cover 6 and the flange portion 48 of the stator mounting member 46,
A spring 50 is arranged to elastically press the flange portion 48 to urge the stator mounting member 46 in the direction opposite to the arrow direction in the drawing.

An actuator (not shown) is connected to the other end 51 of the stator mounting member 46, and the stator mounting member 46 is displaced together with the stator 2 in the direction of the arrow shown by the actuator to move the stator magnetic pole 13 to the stator magnetic pole 13. Rotor magnetic pole 1
By displacing the area facing the armature 6,
Adjust the flux linkage amount of 2. This actuator can be composed of a drive source such as a known solenoid or torque motor, and a drive circuit for driving the drive source. The actuator is controlled by an output signal of a speed detector (not shown) that detects the rotation speed of the electric motor 1 or a vehicle speed corresponding to the rotation speed, and increases as the rotation speed of the electric motor 1 increases. A traction force in the arrow direction is generated, and the axial position of the stator 2 is displaced to a position where the traction force and the elastic force of the spring 50 are balanced. The relationship between the rotation speed N of the electric motor 1 and the interlinkage magnetic flux amount φ of the armature winding 12 when the stator 2 is displaced according to this rotation speed is similar to the relationship shown in FIG. 2 (B). By setting the characteristics of the actuator and the spring 50 so that the output characteristics of the electric motor 1 can be set as shown in FIG.

In the above embodiment, the thrust mechanism in which the stator is axially displaced by the actuator controlled by the detection signal of the rotation speed of the electric motor is used. However, the stator 2 is manually operated in the axial direction. It is also possible to employ a thrust mechanism that displaces. In this case,
The stator 2 of the electric motor 1 is connected to the manual operation member by a connecting means, and the manual operation member is manually operated to displace the stator 2 in the axial direction to form the rotor magnetic pole 16 and the stator magnetic pole 13. Change the facing area of. For example, one end of a wire as a connecting means is coupled to a grip or lever provided on a steering wheel of a vehicle as a manual operation member, and the other end of the wire is coupled to the other end 51 of a stator attachment member 46 (see FIG. 6). To do. In this case, the amount of the interlinkage magnetic flux of the armature winding 12 is adjusted by manually operating the grip or lever according to the rotation speed of the electric motor 1 or the vehicle speed of the vehicle to displace the stator 2 in the axial direction. Then, the output characteristic of the electric motor 1 can be changed.

In each of the above embodiments, the DC motor is
Although the rotor has the outer rotor structure that rotates outside the stator, the electric motor may have the inner rotor structure. In this case, the electric motor has an armature winding wound around each salient pole portion of a stator core in which 3n (n: integer) salient pole portions are projected inward in the radial direction from an annular yoke portion. And a rotor that is disposed inside the stator and has a rotor magnetic pole of 2n poles made of a permanent magnet on the outer periphery, and is formed by the tip of each salient pole portion of the stator core. The stator magnetic pole and the rotor magnetic pole are arranged to face each other in the radial direction. The thrust mechanism as the magnetic flux adjusting means for adjusting the interlinkage magnetic flux amount of the armature winding is
The first embodiment (see FIG. 1) or the second embodiment (see FIG. 6)
As in the case of (1), the relative displacement in the axial direction between the rotor and the stator by means of axially displacing the rotary shaft to which the stator is attached or by axially displacing the stator. Can be used.

FIG. 7 shows the structure of the third embodiment of the present invention. In this embodiment, a DC motor having a structure in which a stator pole and a rotor pole face each other in the axial direction is used. The magnetic flux adjusting means uses a thrust mechanism that causes relative displacement in the axial direction between the rotor and the stator of the electric motor so as to change the gap between the rotor magnetic pole and the stator magnetic pole of the electric motor. It is configured. In FIG. 7, the same reference numerals as those in FIG. 1 are attached to the corresponding portions equivalent to those in FIG.

In FIG. 7, the stator 2 of the electric motor 1 is 3n from the one surface in the axial direction of the yoke 52 having an annular disc shape.
The stator core 54 is formed by projecting (n: integer) salient pole portions 53 in the axial direction, and the armature winding 12 wound around the salient pole portions 53. The 3n salient pole portions 53 are provided so as to be arranged at equal angular intervals in the circumferential direction, and the tips of the salient pole portions 53 serve as the stator magnetic poles 13. The stator 2 is attached to a stator attachment portion 21 of the cover 6 with screws 22.

The rotor 3 of the electric motor 1 has a boss 17 at the center.
And a permanent magnet 56 fixed to the surface of the magnetic path constituting member 55 facing the salient pole portion of the stator core of the magnetic path constituting member 55, the permanent magnet 56 being in the axial direction. 2 n-pole rotor magnetic poles 16 that are magnetized to have different poles arranged alternately in the circumferential direction. The rotor magnetic pole 16 is the stator magnetic pole 1.
3 is opposed in the axial direction with a gap (cap length g).

The rotor 3 is attached to one end of a rotary shaft 7 supported by a bearing 8 so as to be rotatable and slidable in the axial direction, and the other end of the rotary shaft 7 is connected to a wheel 9. Is coupled to the wheel 9 in a state in which only axial displacement is allowed. The thrust mechanism for causing the relative displacement in the axial direction between the rotor 3 and the stator 2 of the electric motor 1 has a rotary shaft 7 in the direction of the arrow shown in the figure, as in the case of the above-described first embodiment. Centrifugal governor mechanism 1 driven to be displaced to
0, and increases the axial gap length g between the stator magnetic pole 13 and the rotor magnetic pole 16 as the rotational speed of the wheel 9 increases, thereby decreasing the amount of interlinkage magnetic flux of the armature winding 12. Works like.

In the above embodiment, the rotating shaft 7 of the rotor 3 of the electric motor is supported so as to be displaceable in the axial direction, and the centrifugal governor mechanism 10 displaces the rotating shaft 7 in the axial direction so that the stator magnetic pole 13 and A magnetic flux adjusting means for changing the gap between the rotor magnetic pole 16 and the rotor magnetic pole 16 is used. As the magnetic flux adjusting means, as in the second embodiment (FIG. 6) described above, the stator 2 of the motor is set in the axial direction. A thrust mechanism in which the gap between the stator magnetic pole and the rotor magnetic pole is changed by displacing the stator 2 in the axial direction according to the rotation speed of the electric motor. It can also be used.

In each of the above embodiments, the other end of the rotary shaft having the rotor of the electric motor attached to one end is directly connected to the wheel. However, the other end of the rotary shaft may be connected to the wheel via a reduction gear mechanism if necessary. You may make it couple | bond with a wheel.

In each of the above embodiments, the DC motor is 2n.
The three-phase structure has a rotor magnetic pole of (n: integer) poles and a stator magnetic pole of 3n poles, but also when both the rotor magnetic pole and the stator magnetic pole have a single phase structure of 2n poles. The present invention can be applied. In this case, the control system for controlling the rotation speed of the electric motor is also a single-phase control system.

[0058]

As described above, according to the present invention, the amount of effective magnetic flux interlinking with the armature winding of the electric motor can be adjusted by the magnetic flux adjusting means, so that the armature can be adjusted according to the rotation speed of the electric motor. The output of the electric motor can be maintained at a high level over a wide range of rotation speed by adjusting the amount of flux linkage in the winding. Therefore, there is an advantage that a large generated torque can be obtained in a low speed range and an electric vehicle drive device capable of high speed rotation can be obtained without using an automatic transmission mechanism or increasing the size of an electric motor.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a structure of a first embodiment of the present invention.

2 is a diagram for explaining the relationship between the rotation speed and the armature flux linkage amount in the embodiment of FIG. 1. FIG.

3 is a circuit diagram showing a configuration example of a control system of the electric motor in the embodiment of FIG.

FIG. 4 is a diagram for explaining output characteristics obtained by the electric motor in the embodiment of FIG.

FIG. 5 is a diagram for explaining traveling characteristics of a vehicle obtained by using the embodiment of FIG.

FIG. 6 is a vertical sectional view showing the structure of the second embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view showing the structure of the third embodiment of the present invention.

FIG. 8 is a diagram comparing and showing differences in motor output when the amount of armature interlinkage magnetic flux of the motor is different.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC motor 2 Stator 3 Rotor 7 Rotating shaft 9 Wheel 10 Centrifugal governor mechanism 11 Stator core 12 Armature winding 13 Stator magnetic pole 16 Rotor magnetic pole

Claims (6)

[Claims] 1. A drive device for an electric vehicle, which rotatably drives wheels of a vehicle using a DC electric motor as a drive source, comprising magnetic flux adjusting means for adjusting an effective magnetic flux amount interlinking with an armature winding of the electric motor. A characteristic drive device for an electric vehicle. 2. The DC motor has a structure in which a rotor magnetic pole and a stator magnetic pole face each other in a radial direction, and the magnetic flux adjusting means defines an opposing area between the rotor magnetic pole and the stator magnetic pole of the motor. The drive device for an electric vehicle according to claim 1, comprising a thrust mechanism that causes a relative displacement in the axial direction between the rotor and the stator of the electric motor so as to change. 3. The rotation shaft of the rotor is coupled to the wheel in a state where only the axial displacement between the rotation shaft and the wheel is allowed, and the thrust mechanism is associated with an increase in the rotation speed of the wheel. The drive device for an electric vehicle according to claim 2, further comprising a centrifugal governor mechanism that drives the rotating shaft so as to reduce an area where the rotor magnetic pole and the stator magnetic pole face each other. 4. The thrust mechanism responds to an output signal of a speed detecting means for detecting a rotation speed of the electric motor, and reduces the facing area between the rotor magnetic pole and the stator magnetic pole of the electric motor as the rotation speed increases. The drive device for an electric vehicle according to claim 2, comprising an actuator that displaces the stator in the axial direction. 5. The thrust mechanism is configured so that a manual operation member connected to a stator of the electric motor and an opposing area between a rotor magnetic pole and a stator magnetic pole of the electric motor are changed by operating the manual operation member. The drive device for an electric vehicle according to claim 2, comprising a manual operation mechanism that displaces the stator in the axial direction. 6. The DC motor has a structure in which a stator magnetic pole and a rotor magnetic pole face each other in the axial direction, and the magnetic flux adjusting means includes a gap between the rotor magnetic pole and the stator magnetic pole of the electric motor. 2. The drive device for an electric vehicle according to claim 1, comprising a thrust mechanism that causes a relative change in the axial direction between the rotor and the stator of the electric motor so as to change.